Hong Kong, China
Hong Kong, China

The University of Hong Kong is the oldest tertiary institution in Hong Kong. Its motto is "Sapientia et Virtus" in Latin, meaning "wisdom and virtue", and "明德格物" in Chinese. The medium of instruction in most classes is English. The school adopts the problem-based learning teaching strategy which aims to train students' problem solving skills. It has a great achievement in Humanities, Legal subjects, Political science, Biological science and Medicine. Wikipedia.

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The subject invention pertains to methods, and related compositions, for treating or inhibiting liver cancer, comprising administering an effective amount of sorafenib; and an inhibiting agent selected from a CD47 inhibiting agent, a NF-B inhibiting agent, and combination thereof.

Annexin A3 (ANAX3) is utilized as a biomarker for the diagnosis and prognosis of hepatocellular carcinoma (HCC) and the utilization of a monoclonal antibody against ANXA3 or antisense polynucleotide against ANXA3 mRNA for the suppression or treatment of HCC, alone or in combination with other HCC treatment. Monoclonal antibody against ANXA3 can be administered for the suppression of tumor growth, metastasis, and chemoresistance.

On field ionization under ambient conditions is described and applied on both ionization and desorption of various chemicals and biochemical present on the surface of materials in solid, liquid or gas states. The Atmospheric Pressure Megavolt Electrostatic Field Ionization Desorption (APME-FID) method generates ions directly from the surface of samples connected to a high electrical voltage at megavolt conditions. Megavolt electrostatic potential is generated and gradually accumulated directly on the sample surface by a Van de Graaff generator without causing damage to the sample. Therefore, when coupled with mass spectrometric system, the APME-FID-MS method enables direct detection of analytes on the surface of samples in different sizes and diverse types.

University of Hong Kong | Date: 2015-08-31

Methods of diagnosis and/or prognosis of malignant disease from pleural effusion samples are disclosed. The methods typically include determining the normalized intensity of one or more biomarkers, such as acetone and 3-hydroxybutyate, in pleural effusion samples using nuclear magnetic resonance (NMR), such as proton NMR (^(1)H-NMR) spectroscopy. Reference values for malignant disease diagnosis using the disclosed biomarkers are provided. Reference values for prognosis of median survival time based on the disclosed biomarkers are also provided.

University of Hong Kong | Date: 2017-03-01

Methods of diagnosis and/or prognosis of malignant disease from pleural effusion samples are disclosed. The methods typically include determining the normalized intensity of one or more biomarkers, such as acetone and 3-hydroxybutyate, in pleural effusion samples using nuclear magnetic resonance (NMR), such as proton NMR (^(1)H-NMR) spectroscopy. Reference values for malignant disease diagnosis using the disclosed biomarkers are provided. Reference values for prognosis of median survival time based on the disclosed biomarkers are also provided.

Ho C.S.H.,University of Hong Kong
Journal of Experimental Child Psychology | Year: 2010

This study examined how four domain-specific skills (arithmetic procedural skills, number fact retrieval, place value concept, and number sense) and two domain-general processing skills (working memory and processing speed) may account for Chinese children's mathematics learning difficulties. Children with mathematics difficulties (MD) of two age groups (7-8 and 9-11. years) were compared with age-matched typically achieving children. For both age groups, children with MD performed significantly worse than their age-matched controls on all of the domain-specific and domain-general measures. Further analyses revealed that the MD children with literacy difficulties (MD/RD group) performed the worst on all of the measures, whereas the MD-only group was significantly outperformed by the controls on the four domain-specific measures and verbal working memory. Stepwise discriminant analyses showed that both number fact retrieval and place value concept were significant factors differentiating the MD and non-MD children. To conclude, deficits in domain-specific skills, especially those of number fact retrieval and place value understanding, characterize the profile of Chinese children with MD. © 2010 Elsevier Inc.

Danchin A.,AMAbiotics SAS | Danchin A.,University of Hong Kong
FEBS Letters | Year: 2012

Using comparative genomics and functional analysis, this work summarises how the cell's genome is organised, with emphasis on the importance of the cell's chassis. Some discrete but important engineering constraints are reviewed, beginning with the need for scaffolds, as well as the question posed by the difficult task of putting a very long random thread (DNA) into a limited volume. Subsequently, to illustrate overlooked essential functions, we show the importance of safety valves, as well as the need to cope with leftovers. The third section discusses how transplantation experiments point out a remarkable feature of the cell factory: the program replicates (makes identical copies of itself), whereas the cell reproduces (makes similar copies of itself), placing in the limelight the role of informational maintenance. A final section identifies the need to put together a globally linear behaviour of the cell with intrisically non-linear genetic constructs. The discussion ends with the central question of evolvability of artificial constructs and to suggest that combining in vivo Synthetic Biology with biochemical reactors might be an efficient way forward. © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Yeoh A.E.J.,National University of Singapore | Tan D.,Raffles Cancer Center and the Singapore General Hospital | Li C.-K.,Chinese University of Hong Kong | Hori H.,Mie University | And 2 more authors.
The Lancet Oncology | Year: 2013

Survival for adults and children with acute lymphoblastic leukaemia has risen substantially in recent years because use of improved risk-directed treatments and supportive care has widened. In nearly all developed countries, multidisciplinary panels of leukaemia experts have formulated clinical practice guidelines in which standard treatment approaches are recommended on the basis of current evidence. However, those guidelines do not take into account resource limitations in low-income countries, including financial and technical challenges. In Asia, huge disparities in economy and infrastructure exist between countries, and even among different regions in some large countries. At a consensus session held as part of the 2013 Asian Oncology Summit in Bangkok, Thailand, a panel of experts summarised recommendations for management of adult and paediatric acute lymphoblastic leukaemia. Strategies were developed for Asian countries on the basis of available financial, skill, and logistical resources and were stratified in a four-tier system according to the resources available in a particular country or region (basic, limited, enhanced, and maximum). © 2013 Elsevier Ltd.

Jha V.,Jawaharlal Institute of Postgraduate Medical Education & Research | Jha V.,George Institute of Global Health | Garcia-Garcia G.,University of Guadalajara | Iseki K.,University of Ryukyus | And 7 more authors.
The Lancet | Year: 2013

Summary Chronic kidney disease is defined as a reduced glomerular filtration rate, increased urinary albumin excretion, or both, and is an increasing public health issue. Prevalence is estimated to be 8-16% worldwide. Complications include increased all-cause and cardiovascular mortality, kidney-disease progression, acute kidney injury, cognitive decline, anaemia, mineral and bone disorders, and fractures. Worldwide, diabetes mellitus is the most common cause of chronic kidney disease, but in some regions other causes, such as herbal and environmental toxins, are more common. The poorest populations are at the highest risk. Screening and intervention can prevent chronic kidney disease, and where management strategies have been implemented the incidence of end-stage kidney disease has been reduced. Awareness of the disorder, however, remains low in many communities and among many physicians. Strategies to reduce burden and costs related to chronic kidney disease need to be included in national programmes for non-communicable diseases. © 2013 Elsevier Ltd.

Mak A.,National University of Singapore | Isenberg D.A.,University College London | Lau C.-S.,University of Hong Kong
Nature Reviews Rheumatology | Year: 2013

Increased longevity of patients with systemic lupus erythematosus (SLE) leads to chronic organ damage accrual, which reduces the possibility of further survival improvement in patients with the disease. Observations from lupus centres worldwide revealed that the prevalence of damage occurring in the cardiovascular system in patients with SLE has increased over the past four decades. The results of a meta-analysis involving over 70 observational studies demonstrated that lupus-related organ damage involving the neuropsychiatric and renal systems also remains a major factor that limits survival improvement in patients with this disease. While efforts to halt acute lupus-related injury are continuing, through early diagnosis and effective use of immunosuppressive agents, a concomitant strategy to improve survival of patients with SLE would be early detection and timely treatment of lupus-related organ damage with meticulous monitoring. This Review discusses the pattern and trend of organ damage in patients with SLE worldwide, the potential serological and genetic mechanisms of organ damage, and the advances in research on potential tools for early detection of lupus-related organ damage, such as functional brain imaging techniques, measurement of endothelial function, identification of biomarkers from body fluids, and development of risk calculation models. © 2013 Macmillan Publishers Limited. All rights reserved.

Si S.,University of Hong Kong | Tao D.,Nanyang Technological University | Geng B.,Peking University
IEEE Transactions on Knowledge and Data Engineering | Year: 2010

The regularization principals [31] lead approximation schemes to deal with various learning problems, e.g., the regularization of the norm in a reproducing kernel Hilbert space for the ill-posed problem. In this paper, we present a family of subspace learning algorithms based on a new form of regularization, which transfers the knowledge gained in training samples to testing samples. In particular, the new regularization minimizes the Bregman divergence between the distribution of training samples and that of testing samples in the selected subspace, so it boosts the performance when training and testing samples are not independent and identically distributed. To test the effectiveness of the proposed regularization, we introduce it to popular subspace learning algorithms, e.g., principal components analysis (PCA) for cross-domain face modeling; and Fisher's linear discriminant analysis (FLDA), locality preserving projections (LPP), marginal Fisher's analysis (MFA), and discriminative locality alignment (DLA) for cross-domain face recognition and text categorization. Finally, we present experimental evidence on both face image data sets and text data sets, suggesting that the proposed Bregman divergence-based regularization is effective to deal with cross-domain learning problems. © 2010 IEEE.

Brownnutt M.,University of Innsbruck | Brownnutt M.,University of Hong Kong | Kumph M.,University of Innsbruck | Rabl P.,Vienna University of Technology | And 2 more authors.
Reviews of Modern Physics | Year: 2015

Electric-field noise near surfaces is a common problem in diverse areas of physics and a limiting factor for many precision measurements. There are multiple mechanisms by which such noise is generated, many of which are poorly understood. Laser-cooled, trapped ions provide one of the most sensitive systems to probe electric-field noise at MHz frequencies and over a distance range 30-3000 μm from a surface. Over recent years numerous experiments have reported spectral densities of electric-field noise inferred from ion heating-rate measurements and several different theoretical explanations for the observed noise characteristics have been proposed. This paper provides an extensive summary and critical review of electric-field noise measurements in ion traps and compares these experimental findings with known and conjectured mechanisms for the origin of this noise. This reveals that the presence of multiple noise sources, as well as the different scalings added by geometrical considerations, complicates the interpretation of these results. It is thus the purpose of this review to assess which conclusions can be reasonably drawn from the existing data, and which important questions are still open. In so doing it provides a framework for future investigations of surface-noise processes. © 2015 American Physical Society.

Lu H.-Z.,University of Hong Kong | Shi J.,Peking University | Shen S.-Q.,University of Hong Kong
Physical Review Letters | Year: 2011

A magnetoconductivity formula is presented for the surface states of a magnetically doped topological insulator. It reveals a competing effect of weak localization and weak antilocalization in quantum transport when an energy gap is opened at the Dirac point by magnetic doping. It is found that, while random magnetic scattering always drives the system from the symplectic to the unitary class, the gap could induce a crossover from weak antilocalization to weak localization, tunable by the Fermi energy or the gap. This crossover presents a unique feature characterizing the surface states of a topological insulator with the gap opened at the Dirac point in the quantum diffusion regime. © 2011 American Physical Society.

Gao Y.,Peking University | Vanhoutte P.M.,University of Hong Kong
Journal of Cardiovascular Pharmacology | Year: 2012

Nebivolol is a highly selective β 1-adrenoceptor blocker, which also stimulates endothelial nitric oxide synthase and scavenges reactive oxygen species (ROS). These characteristics endow nebivolol, compared with conventional β-blockers, with a favorable hemodynamic profile for the treatment of hypertension, chronic heart failure, and possibly other cardiovascular diseases. Nebivolol is a racemic mixture of d- and l-isomers. Its β 1-antagonistic properties reside primarily with d-nebivolol although both isomers are capable of increasing the release of NO from the endothelium after binding to β 2- or β 3- adrenergic receptors. The latter action results in vasodilatation and reduced vascular resistance. Nebivolol also scavenges ROS in a receptor-independent manner by direct interaction with free radicals. By scavenging ROS nebivolol not only reduces oxidant stress but also augments NO bioavailability. The endothelial nitric oxide synthase -stimulating and ROS scavenging effects of nebivolol act synergistically to provide cardiovascular protection in addition to its β 1-antagonistic action. © 2012 Lippincott Williams & Wilkins, Inc.

Chui T.F.M.,University of Hong Kong | Terry J.P.,National University of Singapore
Journal of Hydrology | Year: 2013

Human populations inhabiting remote coral atoll islands in the tropical Pacific Ocean rely heavily on thin unconfined fresh groundwater lenses (FWLs) as their main natural source of potable water. Potential threats to the continuing viability of atoll FWLs may be associated with eustatic sea-level rise (SLR), but little is known about the influence of SLR on the FWLs of different atoll island sizes and the resilience of FWLs to salinization caused by storm-induced wave washover of low-lying land. Here, numerical modelling is carried out to generate steady-state FWL configurations at three chosen island sizes (400, 600 and 800. m widths), upon which a 40. cm SLR scenario is imposed, followed by transient simulations to assess saline damage and recovery over a 1-year period after a storm washover event on a 600. m wide island.Two different approaches are tested for taking into account the existence of a freshwater swamp, formed where a topographic depression exposes the central region of a FWL above the ground surface. These 'groundwater window' and 'specified flux' approaches yield similar results, implying that complex integrated surface and groundwater modelling may be unnecessary to develop realistic models of FWL configuration where central freshwater swamps exist. Thereafter, steady-state solutions indicate how FWL dimensions are not related in a linear manner to atoll island size, such that smaller islands develop much more restricted lenses than larger islands. Partly in consequence, smaller FWLs display greater potential for disturbance by SLR, while larger and more robust FWLs may show more resilience. Results from simulation of saline damage caused by storm washover produce a somewhat counterintuitive finding: in a post-SLR situation it is apparent that FWL vulnerability to washover salinization may actually be reduced, owing to the thinner layer of unsaturated substrate lying above the water table (i.e. FWL surface), into which saline water can infiltrate and accumulate during a storm washover event. © 2013 Elsevier B.V.

Chen Y.-Y.,Taipei City Hospital | Chen Y.-Y.,National Yang Ming University | Chien-Chang Wu K.,National Taiwan University | Chien-Chang Wu K.,National Taiwan University Hospital | And 2 more authors.
Epidemiologic Reviews | Year: 2012

Asian countries account for approximately 60% of the world's suicides, but there is a great mismatch in the region between the scale of the problem and the resources available to tackle it. Despite certain commonalities, the continent itself is culturally, economically, and socially diverse. This paper reviews current epidemiologic patterns of suicide, including suicide trends, sociodemographic factors, urban/rural living, suicide methods, sociocultural religious influences, and risk and protective factors in Asia, as well as their implications. The observed epidemiologic distributions of suicides reflect complex interplays among the traditional value/culture system, rapid economic transitions under market globalization, availability/desirability of suicide methods, and sociocultural permission/prohibitions regarding suicides. In general, compared with Western countries, Asian countries still have a higher average suicide rate, lower male-to-female suicide gender ratio, and higher elderly-to-general-population suicide ratios. The role of mental illness in suicide is not as important as that in Western countries. In contrast, aggravated by access to lethal means in Asia (e.g., pesticide poisoning and jumping), acute life stress (e.g., family conflicts, job and financial security issues) plays a more important role than it does in Western countries. Some promising suicide prevention programs in Asia are illustrated. Considering the specific socioeconomic and cultural aspects of the region, community-based suicide intervention programs integrating multiple layers of intervention targets may be the most feasible and cost-effective strategy in Asia, with its populous areas and limited resources. © The Author 2011. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved.

Li Y.,University of Hong Kong | Nielsen P.V.,University of Aalborg
Indoor Air | Year: 2011

There has been a rapid growth of scientific literature on the application of computational fluid dynamics (CFD) in the research of ventilation and indoor air science. With a 1000-10,000 times increase in computer hardware capability in the past 20 years, CFD has become an integral part of scientific research and engineering development of complex air distribution and ventilation systems in buildings. This review discusses the major and specific challenges of CFD in terms of turbulence modelling, numerical approximation, and boundary conditions relevant to building ventilation. We emphasize the growing need for CFD verification and validation, suggest ongoing needs for analytical and experimental methods to support the numerical solutions, and discuss the growing capacity of CFD in opening up new research areas. We suggest that CFD has not become a replacement for experiment and theoretical analysis in ventilation research, rather it has become an increasingly important partner. © 2011 John Wiley & Sons A/S.

Kalfat R.,Swinburne University of Technology | Al-Mahaidi R.,Swinburne University of Technology | Smith S.T.,University of Hong Kong
Journal of Composites for Construction | Year: 2013

Abstract The anchorage of fiber-reinforced polymer (FRP) composites when applied to reinforced concrete (RC) structures as externally bonded reinforcement is an effective means to achieve higher levels of fiber utilization prior to premature debonding failure. Commonly documented anchorage methods for FRP-to-concrete applications demonstrating encouraging results include FRP U-jackets, FRP anchors (also known as spike anchors, among other names), patch anchors (utilizing unidirectional and bidirectional fabrics), nailed metal plates (also known as hybrid bonding), near-surface mounted rods, mechanical fastening, concrete embedment, and mechanical substrate strengthening. Anchorages applied to FRP systems have been verified through experimental testing and numerical modeling to increase the ductility, deformability, and strength of the member and also prevent, delay, or shift the critical mode of FRP debonding failure. Although the benefits of anchorage solutions have now been widely acknowledged by researchers, further studies are required in order to establish reliable design formulations to negate the requirement for ongoing laboratory verification by industry. The present paper is a state-of-the-art review of experimental studies conducted in the area of FRP anchorage systems applied to FRP-strengthened RC flexural members. Available experimental data are compiled and catalogued and an anchorage efficiency factor for each anchorage type under investigation is assigned in order to quantify the anchor's efficiency. Finally, current shortcomings in knowledge are identified, in addition to areas needing further investigation. © 2013 American Society of Civil Engineers.

Agency: Cordis | Branch: FP7 | Program: CSA-CA | Phase: HEALTH-2007-2.1.2-7 | Award Amount: 1.12M | Year: 2009

In contrast to the reductionist approach of Western medicine that is based on modern anatomy, cell and molecular biology, Traditional Chinese Medicine (TCM) uses a unique theory system and an individualised and holistic approach to describe health and disease, based on the philosophy of Yin-Yang balance and an emphasis on harmony of functions. These two medicine systems disagree with each other in many situations as both of them may observe health from their limited perspective. GP-TCM aims to inform best practice and harmonise research of the safety and efficacy of TCM, especially Chinese herbal medicines (CHM) and acupuncture, in EU Member States using a functional genomics approach through exchange of opinions, experience and expertise among scientists in EU Member States and China. In 10 proposed work packages, we will take actions to review the current status, identify problems and solutions in the quality control, extraction and analysis of CHM. While these fundamental issues are addressed, discussion forums emphasising the use of functional genomics methodology in research of the safety, efficacy and mechanisms of CHM and acupuncture will be the core of this Coordination project. It will include the application of the technique in cell-based models, animal models and in clinical studies. Guidelines about good practice and agreed protocols in related research areas will be published to promote future TCM research in all the EU member states; online tools and research resources will be made available to EU member states; EU member states and additional China partners will be invited to join this network; The GP-TCM Research Association will be established during this project and kept running autonomously to continue the guidance and coordination of EU-China collaboration in TCM research.

News Article | November 7, 2016
Site: globenewswire.com

NEW YORK, Nov. 07, 2016 (GLOBE NEWSWIRE) -- Sotheby’s announced today that Linus Wing Lam Cheung has been unanimously elected to join the Company’s Board of Directors. Mr. Cheung is the retired Chief Executive Officer of Hong Kong Telecom and a renowned collector of Chinese Art. “Linus brings a wealth of business experience and sophistication to our Board and company,” said Domenico De Sole, Chairman of Sotheby’s Board of Directors. “His unique insights on Asia, as well as the many areas in which Sotheby’s operates, will be incredibly valuable.  Having had the pleasure of knowing him as a client for years, we are very pleased to now welcome him as an independent Director.” Mr. Cheung served as Executive Chairman of Asia Television Limited from 2008 to 2009, Chief Executive Officer of Hong Kong Telecom from 1994 to 2000 and, following Hong Kong Telecom’s merger with Pacific Century Cyberworks (PCCW) in 2000, PCCW’s Deputy Chairman until 2004.  Prior to joining Hong Kong Telecom, Mr. Cheung spent 23 years at Cathay Pacific Airways where he concluded his tenure as Deputy Chief Executive Officer. “I am delighted to be joining the Board of Sotheby’s, a company I have long admired during my decades as a collector,” commented Mr. Cheung.  “As the art market continues to evolve and grow in China and across Asia, I look forward to sharing my expertise and experience to best position the Company for future success.” Mr. Cheung has served on the board of China Unicom Ltd. since 2004 and HK Resort International Ltd. since 2006.  Previously, he served on the boards of Cathay Pacific Airways, Hong Kong Telecom, Cable and Wireless plc, and Taikang Insurance. In addition to his past executive leadership positions, Mr. Cheung has been actively involved with his alma mater, the University of Hong Kong, where he earned a BSocSc degree with honors and a Diploma in Management Studies with distinction. He spent 10 years as a member of the Council of the University of Hong Kong and also served as Chairman of the University of Hong Kong School of Professional and Continuing Education and as Chairman of the Centennial College. In connection with Mr. Cheung’s appointment, Sotheby’s and its largest shareholder, Taikang Insurance Group, have entered into an agreement whereby Taikang has agreed it will not increase its ownership position beyond 15% for a period of three years, subject to certain conditions. About Sotheby’s Sotheby’s has been uniting collectors with world-class works of art since 1744. Sotheby’s became the first international auction house when it expanded from London to New York (1955), the first to conduct sales in Hong Kong (1973), India (1992) and France (2001), and the first international fine art auction house in China (2012). Today, Sotheby’s presents auctions in 10 different salesrooms, including New York, London, Hong Kong and Paris, and Sotheby’s BidNow program allows visitors to view all auctions live online and place bids from anywhere in the world. Sotheby’s offers collectors the resources of Sotheby’s Financial Services, the world’s only full-service art financing company, as well as private sale opportunities in more than 70 categories, including S|2, the gallery arm of Sotheby's Contemporary Art department, and two retail businesses, Sotheby’s Diamonds and Sotheby’s Wine. Sotheby’s has a global network of 80 offices in 40 countries and is the oldest company listed on the New York Stock Exchange (BID). For More News from Sotheby’s News & Video: http://www.sothebys.com/en/news-video.html  Twitter: www.twitter.com/sothebys Facebook: www.facebook.com/sothebys Instagram: www.instagram.com/sothebys  Snapchat ID: sothebys Weibo: www.weibo.com/sothebyshongkong WeChat ID: sothebyshongkong Browse sale catalogues, view original content, stream live auctions and more at www.sothebys.com, and through Sotheby’s apps for iPhone, iPad, Android, Apple TV and Amazon Fire

Arabidopsis overexpressing AtPAP2 (Experimental) grow faster than control plants (Control) under both short and long days. Credit: The University of Hong Kong Do you feel the heat? According to NASA and NOAA, 2014 was the hottest year since 1880 and the 10 warmest years in the instrumental record have occurred since 1998. The Intergovernmental Panel of Climate Change (IPCC) of the United Nations confirmed in its Fifth Assessment Report that cumulative emissions of carbon dioxide (CO2) largely determine global mean surface warming and predicted that by 2100, the global mean surface temperature may increase by 3.7 oC to 4.8oC over the average for 1850-1900 for a median climate response if there is no additional effort to reduce greenhouse gas emission is put in place. To alleviate the problem and slow down the rate of global warming, increasing the rate of CO2 absorption by plants or algae is one possible strategy. A research team led by Dr. Lim Boon-leong with his former PhD student Dr. Law Yee-song from the School of Biological Sciences, Faculty of Science, the University of Hong Kong (HKU), has developed a new strategy to promote plant growth and seed yield by 38% to 57% in a model plant Arabidopsis thaliana, hence increasing CO2 absorption from the atmosphere. This technology may also have potential in boosting food production and thus could solve another danger of human civilization: food shortage due to overpopulation. According to the World Population Prospect of the United Nations in 2015, the global population will reach more than 9.7 billion by 2050, meaning a 57% increase since 2000. In this technology, the researchers have identified a plant-growth promoting gene, designated as "Purple acid phosphatase 2" (AtPAP2) from the model plant Arabidopsis thaliana. AtPAP2 is dually targeted to two energy-generating organelles of plant cells: chloroplasts and mitochondria. Chloroplasts carry out photosynthesis, a process that fixes CO2 in atmosphere into sugars using solar energy. The sugars are then used for plant growth including cell wall, biomass and seeds, or consumed by mitochondria to produce adenosine triphosphate (ATP), an important energy source for many cellular processes. This is the first study of AtPAP2 in the world. The research team found that by dual expression of AtPAP2 on chloroplasts and mitochondria, the engineered plants can grow faster (see Figure 1) and produce 38% to 57% more seeds (see Figure 2). It is because AtPAP2 can modulate the import of a number of specific proteins into chloroplasts and mitochondria, and subsequently boost their capability to harvest solar energy and generate ATP. AtPAP2 is found to be the first protein that can modulate energy outputs from these two organelles simultaneously. Dr Lim have reported the findings in two international conferences, the 9th International Conference for Plant Mitochondrial Biology held in May 2015 in Poland and the 2nd FEBS Plant Organellar Signaling Workshop in September 2015 in Croatia, where Dr. Lim was the only speaker from Hong Kong and China respectively. This research has yielded eight research articles in journals including Plant Physiology, Biofuels and Biotechnology, as well as several patent applications with the assistance of Technology Transfer Office, HKU, and we wish the technology can be transformed into applications. Dr. Lim said: "We are happy to make this discovery which has aroused great interest from many plant scientists, as our research findings would allow plant scientists to study the impacts of high energy supply to various biological processes in plant cell, and to study how energy supply affects plants' abilities to cope with various biotic and abiotic stresses. However, it is just the beginning of a number of research projects, and funding support from the community is certainly essential for future discoveries."

In recent years, scientists have been researching on how to improve drought resistance in plants, so as to enhance growth and productivity of crops in dry weather conditions. A ground breaking technology from the University of Hong Kong (HKU) may provide a solution to this problem on drought stress. The technology, currently with patent pending in different countries, has just been licensed to an internationally recognized agricultural company specializing in the development of new varieties of the oil crops Camelina sativa. The Chye Lab at HKU, funded by the Wilson and Amelia Wong Endowment Fund, has identified a gene from the model plant Arabidopsis thaliana which encodes an acyl-CoA-binding protein (ACBP). The gene, designated as ACBP2, can confer drought tolerance in transgenic Arabidopsis. Overexpression of ACBP2 (i.e. increase in ACBP2 protein in the plant) in these transgenic lines promoted stomatal closure, reduced water loss and enhanced drought tolerance. Professor Chye Mee Len, Wilson and Amelia Wong Professor in Plant Biotechnology at the HKU School of Biological Sciences, and her lab members have discovered in the past years that Arabidopsis acyl-CoA-binding proteins can confer stress tolerance in transgenic Arabidopsis plants. Arabidopsis was used as a model plant because it can be easily manipulated in the lab - it has a small genome, a short life cycle and well-developed genetics. Discoveries can be rapidly made in model plants to enable researchers achieve fundamental knowledge for applications in more complex plant species with larger genomes. Professor Chye said: "Drought stress adversely affects plant growth, and reduces plant yield and food production in agriculture. The stomata, found in leaves and stems, hold the key to water loss in plants and ACBP2 was observed to be expressed in the guard cells which regulate stomatal aperture. ACBP2 was induced by drought and the phytohormone, abscisic acid (ABA) which triggers a pathway in drought protection. ACBP2-overexpressing plants showed ABA-mediated reactive oxygen species (ROS) production in the guard cells, thereby promoting stomatal closure. In contrast, the acbp2 mutant plants, which had lost ACBP2 function and served as one of the controls in the research, were more sensitive to drought stress. " Professor Chye further explained: "ACBP2 overexpression up-regulated the expression of Respiratory Burst Oxidase Homolog D (AtrbohD) and AtrbohF, two NAD (P)H oxidases essential for ABA-mediated ROS production, whereas the expression of Hypersensitive to ABA1 (HAB1), an important negative regulator in ABA signalling, was down-regulated. These observations support a positive role for ACBP2 in promoting ABA signalling in the drought response." The work was published in the journal, Plant Cell and Environment (Vol. 36: pages 300-314), in 2013 with Dr Du Zhi-yan from the Chye Lab as the first author. Dr. Du is a named co-inventor on the recent patent application. The invention has been licensed to Agragen LLC., an internationally recognized agricultural company whose main business is on Camelina sativa, a biofuel and biolubricant production crop, for potential applications in oil production and commercialization. Camelina sativa is known to have a number of advantages over other traditional oil crops, including its wide adaptability to harsh weather conditions, and it has lower fertilizer and pesticide requirements. It can be grown on marginal land, and can be used as a rotation crop with wheat, corn and sorghum. Hence, Camelina sativa represents a promising platform in the production of renewable energy, and the use of HKU technologies to generate potentially drought-tolerant Camelina varieties will make it even more efficient as a source of biofuel. The commercialization of this technology was assisted by the HKU Technology Transfer Office, and Versitech Limited, the commercial arm of the University operating on a non-profit making basis to promote technology innovations by HKU researchers. Explore further: On guard against drought

News Article | February 21, 2017
Site: www.businesswire.com

HONG KONG--(BUSINESS WIRE)--Beijing Gas Blue Sky Holdings Limited (“the Company” or “Beijing Gas Blue Sky”, together with its subsidiaries, the “Group”, HKSE stock code: 6828) is pleased to announce that, Mr. Li Weiqi has been appointed as an executive director of the Company and a vice president of the Group; and Mr. Pang Siu Yin has been appointed as an independent non-executive director of the Company, with immediate effect. Mr. Li Weiqi, aged 42, obtained a Bachelor degree of City Gas Engineering from Beijing Construction Engineering College (now Beijing University of Civil Engineering and Architecture) in 1998. Mr. Li has over 18 years of experience in gas design, strategic planning, infrastructure investment and market development. Prior to joining the Company, Mr. Li served as the deputy manager of planning and development of Beijing Gas Group from 2011 to 2016. Mr. Li also held various positions of designer, consultant, business manager and deputy head of marketing in Beijing Gas and Heating Engineering Design Institute for 11 years. Mr. Pang Siu Yin, aged 57, graduated from the University of Leeds with a bachelor of laws degree, obtained a master of business administration degree from the University of Aston, as well as a postgraduate certificate in laws from the University of Hong Kong respectively. Mr. Pang has been a practising solicitor of the high court of Hong Kong since 1990 and was also admitted as a solicitor in England and Wales in 1997. He is currently a partner of LCP, a firm of solicitors in Hong Kong, with his practice focusing on commercial and litigation. Mr. Pang was appointed as an independent non-executive director of Winto Group (Holdings) Limited (stock code: 8238) on 24 July 2015 and an independent non-executive director of Man Sang Jewellery Holdings Limited (stock code: 1466) on 19 November 2016. Mr. Tommy Cheng, Co-Chairman and Executive Director of the Group states that “We are pleased to invite Mr. Li and Mr. Pang as our Board member. Both of them have extensive experience and achieve outstanding performance in related industry. Prior to joining the Company, Mr. Li developed his career in Beijing Gas Group, which is our single largest shareholder since 2016. We believe that the joining of Mr. Li and Mr. Pang will be definitely beneficial to the Group’s development. We are looking forward to working with them closely to further enhance the level of corporate governance of the Group, as well as to promote the Group's business development in the future.” Beijing Gas Blue Sky Holdings Limited (“Beijing Gas Blue Sky”, HKSE stock code: 6828) is an integrated natural gas provider, distributor and operator, with an emphasis on the midstream and downstream natural gas development. Our natural gas business includes: (i) construction and operation of compressed natural gas (“CNG”) and liquefied natural gas (“LNG”) refueling stations for vehicles; (ii) construction of natural gas pipelines and operation of city gas projects by providing piped gas; (iii) direct supply of LNG to end-users; and (iv) trading and distribution of CNG and LNG. The Group has adapted to the “One Belt One Road” policy, and focus on operating and investing natural gas business. The Group is actively expanding its business development and distribution, as well as continues to gradually expanding the scale of operations. Currently, the Group has business presence in several provinces in Northeast China, East China, Central South China and Southwest China, including Liaoning Province, Shandong Province, Anhui Province, Zhejiang Province, Hubei Province, Guizhou Province, Sichuan Province and Hainan Province, etc. In the future, The Group is committed to its vision "develop clean energy, enhance customer value, create a beautiful blue sky". It will continue to actively investing and developing natural gas business, as well as participating in the development of natural gas industry value chain.

News Article | November 10, 2016
Site: www.sciencedaily.com

A team of researchers led by Dr Jinyao Tang of the Department of Chemistry, the University of Hong Kong, has developed the world's first light-seeking synthetic nanorobot. With size comparable to a blood cell, those tiny robots have the potential to be injected into patients' bodies, helping surgeons to remove tumors and enabling more precise engineering of targeted medications. The findings have been published in October earlier in leading scientific journal Nature Nanotechnology. It has been a dream in science fiction for decades that tiny robots can fundamentally change our daily life. The famous science fiction movie "Fantastic Voyage" is a very good example, with a group of scientists driving their miniaturized Nano-submarine inside human body to repair a damaged brain. In the film "Terminator 2," billions of nanorobots were assembled into the amazing shapeshifting body: the T-1000. In the real world, it is quite challenging to make and design a sophisticated nanorobot with advanced functions. The Nobel Prize in Chemistry 2016 was awarded to three scientists for "the design and synthesis of molecular machines." They developed a set of mechanical components at molecular scale which may be assembled into more complicated Nano machines to manipulate single molecule such as DNA or proteins in the future. The development of tiny nanoscale machines for biomedical applications has been a major trend of scientific research in recent years. Any breakthroughs will potentially open the door to new knowledge and treatments of diseases and development of new drugs. One difficulty in nanorobot design is to make these nanostructures sense and respond to the environment. Given each nanorobot is only a few micrometer in size which is ~50 times smaller than the diameter of a human hair, it is very difficult to squeeze normal electronic sensors and circuits into nanorobots with reasonable price. Currently, the only method to remotely control nanorobots is to incorporate tiny magnetic inside the nanorobot and guide the motion via external magnetic field. The nanorobot developed by Dr Tang's team use light as the propelling force, and is the first research team globally to explore the light-guided nanorobot and demonstrate its feasibility and effectiveness. In their paper published in Nature Nanotechnology, Dr Tang's team demonstrated the unprecedented ability of these light-controlled nanorobots as they are "dancing" or even spell a word under light control. With a novel nanotree structure, the nanorobots can respond to the light shining on it like moths being drawn to flames. Dr Tang described the motions as if "they can "see" the light and drive itself towards it." The team gained inspiration from natural green algae for the nanorobot design. In nature, some green algae have evolved with the ability of sensing light around it. Even just a single cell, these green algae can sense the intensity of light and swim towards the light source for photosynthesis. Dr Jinyao Tang's team spent three years to successfully develop the nanorobots. With a novel nanotree structure, they are composed of two common and low-price semiconductor materials: silicon and titanium oxide. During the synthesis, silicon and titanium oxide are shaped into nanowire and then further arranged into a tiny nanotree heterostructure. Dr Tang said: "Although the current nanorobot cannot be used for disease treatment yet, we are working on the next generation nanorobotic system which is more efficient and biocompatible." "Light is a more effective option to communicate between microscopic world and macroscopic world. We can conceive that more complicated instructions can be sent to nanorobots which provide scientists with a new tool to further develop more functions into nanorobot and get us one step closer to daily life applications," he added.

News Article | November 8, 2016
Site: www.eurekalert.org

A team of researchers led by Dr Jinyao Tang of the Department of Chemistry, the University of Hong Kong, has developed the world's first light-seeking synthetic Nano robot. With size comparable to a blood cell, those tiny robots have the potential to be injected into patients' bodies, helping surgeons to remove tumors and enabling more precise engineering of targeted medications. The findings have been published in October earlier in leading scientific journal Nature Nanotechnology. It has been a dream in science fiction for decades that tiny robots can fundamentally change our daily life. The famous science fiction movie "Fantastic Voyage" is a very good example, with a group of scientists driving their miniaturized Nano-submarine inside human body to repair a damaged brain. In the film "Terminator 2", billions of Nanorobots were assembled into the amazing shapeshifting body: the T-1000. In the real world, it is quite challenging to make and design a sophisticated Nano robot with advanced functions. The Nobel Prize in Chemistry 2016 was awarded to three scientists for "the design and synthesis of molecular machines". They developed a set of mechanical components at molecular scale which may be assembled into more complicated Nano machines to manipulate single molecule such as DNA or proteins in the future. The development of tiny nanoscale machines for biomedical applications has been a major trend of scientific research in recent years. Any breakthroughs will potentially open the door to new knowledge and treatments of diseases and development of new drugs. One difficulty in Nanorobot design is to make these nanostructures sense and respond to the environment. Given each Nanorobot is only a few micrometer in size which is ~50 times smaller than the diameter of a human hair, it is very difficult to squeeze normal electronic sensors and circuits into Nanorobots with reasonable price. Currently, the only method to remotely control Nanorobots is to incorporate tiny magnetic inside the Nanorobot and guide the motion via external magnetic field. The Nanorobot developed by Dr Tang's team use light as the propelling force, and is the first research team globally to explore the light-guided Nanorobot and demonstrate its feasibility and effectiveness. In their paper published in Nature Nanotechnology, Dr Tang's team demonstrated the unprecedented ability of these light-controlled Nanorobots as they are "dancing" or even spell a word under light control. With a novel Nanotree structure, the Nanorobots can respond to the light shining on it like moths being drawn to flames. Dr Tang described the motions as if "they can "see" the light and drive itself towards it". The team gained inspiration from natural green algae for the Nanorobot design. In nature, some green algae have evolved with the ability of sensing light around it. Even just a single cell, these green algae can sense the intensity of light and swim towards the light source for photosynthesis. Dr Jinyao Tang's team spent three years to successfully develop the Nanorobots. With a novel Nanotree structure, they are composed of two common and low-price semiconductor materials: silicon and titanium oxide. During the synthesis, silicon and titanium oxide are shaped into nanowire and then further arranged into a tiny Nanotree heterostructure. Dr Tang said: "Although the current Nanorobot cannot be used for disease treatment yet, we are working on the next generation nanorobotic system which is more efficient and biocompatible." "Light is a more effective option to communicate between microscopic world and macroscopic world. We can conceive that more complicated instructions can be sent to Nanorobots which provide scientists with a new tool to further develop more functions into Nanorobot and get us one step closer to daily life applications," he added.

News Article | November 10, 2016
Site: www.nanotech-now.com

Abstract: A team of researchers led by Dr Jinyao Tang of the Department of Chemistry, the University of Hong Kong, has developed the world's first light-seeking synthetic Nano robot. With size comparable to a blood cell, those tiny robots have the potential to be injected into patients' bodies, helping surgeons to remove tumors and enabling more precise engineering of targeted medications. The findings have been published in October earlier in leading scientific journal Nature Nanotechnology. It has been a dream in science fiction for decades that tiny robots can fundamentally change our daily life. The famous science fiction movie "Fantastic Voyage" is a very good example, with a group of scientists driving their miniaturized Nano-submarine inside human body to repair a damaged brain. In the film "Terminator 2", billions of Nanorobots were assembled into the amazing shapeshifting body: the T-1000. In the real world, it is quite challenging to make and design a sophisticated Nano robot with advanced functions. The Nobel Prize in Chemistry 2016 was awarded to three scientists for "the design and synthesis of molecular machines". They developed a set of mechanical components at molecular scale which may be assembled into more complicated Nano machines to manipulate single molecule such as DNA or proteins in the future. The development of tiny nanoscale machines for biomedical applications has been a major trend of scientific research in recent years. Any breakthroughs will potentially open the door to new knowledge and treatments of diseases and development of new drugs. One difficulty in Nanorobot design is to make these nanostructures sense and respond to the environment. Given each Nanorobot is only a few micrometer in size which is ~50 times smaller than the diameter of a human hair, it is very difficult to squeeze normal electronic sensors and circuits into Nanorobots with reasonable price. Currently, the only method to remotely control Nanorobots is to incorporate tiny magnetic inside the Nanorobot and guide the motion via external magnetic field. The Nanorobot developed by Dr Tang's team use light as the propelling force, and is the first research team globally to explore the light-guided Nanorobot and demonstrate its feasibility and effectiveness. In their paper published in Nature Nanotechnology, Dr Tang's team demonstrated the unprecedented ability of these light-controlled Nanorobots as they are "dancing" or even spell a word under light control. With a novel Nanotree structure, the Nanorobots can respond to the light shining on it like moths being drawn to flames. Dr Tang described the motions as if "they can "see" the light and drive itself towards it". The team gained inspiration from natural green algae for the Nanorobot design. In nature, some green algae have evolved with the ability of sensing light around it. Even just a single cell, these green algae can sense the intensity of light and swim towards the light source for photosynthesis. Dr Jinyao Tang's team spent three years to successfully develop the Nanorobots. With a novel Nanotree structure, they are composed of two common and low-price semiconductor materials: silicon and titanium oxide. During the synthesis, silicon and titanium oxide are shaped into nanowire and then further arranged into a tiny Nanotree heterostructure. Dr Tang said: "Although the current Nanorobot cannot be used for disease treatment yet, we are working on the next generation nanorobotic system which is more efficient and biocompatible." "Light is a more effective option to communicate between microscopic world and macroscopic world. We can conceive that more complicated instructions can be sent to Nanorobots which provide scientists with a new tool to further develop more functions into Nanorobot and get us one step closer to daily life applications," he added. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Experts advocate the two cities join force in formation of complementary advantages to foster international competitiveness HONG KONG, CHINA--(Marketwired - Feb 15, 2017) - New research released today by the professors of The Chinese University of Hong Kong (CUHK) Business School's Center for Entrepreneurship (CfE) and Hong Kong Baptist University (HKBU)'s School of Business shows that entrepreneurship in Hong Kong and Shenzhen is on the rise. A collaborative effort by CUHK CfE, HKBU School of Business, the University of Hong Kong's Faculty of Business and Economics, Shenzhen Academy of Social Science and Savantas Policy Research Institute, the research titled "Global Entrepreneurship Monitor (GEM) Hong Kong and Shenzhen Report 2016-17" provides a detailed analysis of the current status of entrepreneurship in Hong Kong and Shenzhen. The study compares the results with past indicators for both ecosystems and provides an international benchmark with 65 economies worldwide. It is part of the global initiative, Global Entrepreneurship Monitor (GEM), the world's foremost comparative entrepreneurship study and a trusted resource on entrepreneurship for key international organizations such as the United Nations, World Economic Forum, World Bank and more. In the recent few years, Hong Kong and Shenzhen have experienced an explosive growth in the start-up support ecosystem. The GEM Hong Kong and Shenzhen Report 2016-17 shows that the start-up rates recorded a staggering increase in Hong Kong and Shenzhen from 2009 to 2016. In mid-2016, the early-stage entrepreneurial activity among the adult population was estimated at 9.44 percent (3.64 percent in 2009) in Hong Kong and 16.04 percent (4.8 percent in 2009) in Shenzhen. The growth has been driven by a rapid increase in Shenzhen's new* (+284 percent) and Hong Kong's growth in nascent** businesses (+206 percent) in comparison with 2009 statistics. The prevalence rates of established businesses recorded an increase as well: +389 percent for Shenzhen and +109 percent for Hong Kong. It is worth noting that while entrepreneurship rates are on the rise in Hong Kong and Shenzhen, they are declining in other places in China. Both cities have developed a separate start-up culture and entrepreneurial ecosystem that operate independently from the rest of the Mainland. The positive changes were not limited to early entrepreneurship rates only. The research team also observed a major shift in attitudes and entrepreneurial intentions. In particular, 56.8 percent of the adult population perceives start-up opportunities in Hong Kong. In Shenzhen, the same proportion of individuals who declared they possessed necessary skills and knowledge to start a new business (35.8 percent), also reported their intention to start a business in the next two years (36 percent). Comparing to 2009, the population with entrepreneurial intentions in Hong Kong grew from 7.3 percent to 19.7 percent in 2016, representing an impressive increase of +170 percent. Similarly, in Shenzhen the intentions grew from 17.6 percent to 36 percent, an increase of +105 percent. According to the study, cultural conditioning and attitudes towards entrepreneurship, perception of own skills, and exposure to entrepreneurship practices all had a positive impact on intentions to start businesses. Successful entrepreneurs are also regaining their high status and are promoted by local media in Shenzhen and Hong Kong. In terms of financial support, Hong Kong early-stage firms have lower capital requirements than that of their Shenzhen counterparts, which may be related to the lower technological intensity of Hong Kong firms. 92 percent of nascent entrepreneurs in the two cities declared that their principal source of financial support was their own savings. The role of the family in financing new ventures is still significant in Shenzhen, but not so much in Hong Kong. Banks are also more supportive of startups in Shenzhen than in Hong Kong and so are venture capitalists, which could be explained by a higher prevalence of start-ups with profound market impact. In Hong Kong, on the other hand, crowdfunding is more prevalent as the source of capital for early-stage businesses, a sign of a more established product innovation. Aligned with higher entrepreneurship rates, the research team also found a growing culture of informal investors developing in both cities. Shenzhen observed a much higher informal investment prevalence rate (20.5 percent) than Hong Kong (6.5 percent) of the adult population. In fact, Hong Kong and Shenzhen informal investors were two of the most generous among all economies in the study with a contribution of US$70,565 and US$76,112 respectively. The study has also recorded a dramatic change in investment patterns for Shenzhen. While in 2009 individuals were rather investing in family members, in 2016, friends and neighbors had been the first choice which was aligned with that of Hong Kong. In addition, the research team interviewed 39 Hong Kong and 37 Shenzhen experts in the field of entrepreneurship about their opinions on how the cooperation between Hong Kong and Shenzhen that would increase the cities' international competitiveness. The most frequent recommendation was to leverage the natural industry compatibilities between Hong Kong and Shenzhen. Other recommendations include: Prof. Kevin Au, Associate Director of CUHK CfE and Associate Professor of the Department of Management at CUHK Business School, says: "If Hong Kong and Shenzhen join forces in the formation of complementary advantages on entrepreneurship, it would strengthen the international and Mainland competitiveness for both. This can be the first step towards the development of the Hong Kong-Shenzhen megalopolis." Dr. Marta K. Dowejko, Research Assistant Professor in Entrepreneurship of the Department of Management at HKBU School of Business, says: "Hong Kong and Shenzhen are facing a fantastic opportunity: that of being in the perfect position to build a highly unique and internationally competitive start-up hub with an unparalleled ecosystem compatibility between the two cities and a supportive informal investment culture. While Shenzhen's start-ups are well geared to deliver innovative ideas with high growth potential, Hong Kong's entrepreneurs possess the know-how in taking ideas to the next level and ensuring their long-term sustainability. The results from this year's GEM report give testament to this unique setup that no other place in the world has." * 3 to 42 months old businesses ** in the process of starting up, less than three months old About CUHK Business School CUHK Business School comprises two schools -- Accountancy and Hotel and Tourism Management -- and four departments -- Decision Sciences & Managerial Economics, Finance, Management and Marketing. Established in Hong Kong in 1963, it is the first business school to offer BBA, MBA and Executive MBA programs in the region. Today, the School offers 8 undergraduate programs and 13 graduate programs including MBA, EMBA, Master, MSc, MPhil and PhD. In the Financial Times Global MBA Ranking 2017, CUHK MBA is ranked 36th. In FT's 2016 EMBA ranking, CUHK EMBA is ranked 37th in the world. CUHK Business School has the largest number of business alumni (32,000+) in Hong Kong -- many of whom are key business leaders. The School currently has about 4,400 undergraduate and postgraduate students and Professor Kalok Chan is the Dean of CUHK Business School. More information is available at: www.bschool.cuhk.edu.hk or by connecting with CUHK Business School on Facebook: www.facebook.com/cuhkbschool and LinkedIn: www.linkedin.com/company/cuhk-business-school. About HKBU School of Business Since 1956, HKBU School of Business has provided innovative business education to students from across the globe. We seek to inspire good business practice, create value for stakeholders, and enhance social and economic growth and development through our research on corporate sustainability issues, encompassing the areas of business ethics, corporate social responsibility and corporate governance. About Faculty of Business and Economics, The University of Hong Kong The Faculty of Business and Economics at The University of Hong Kong strives to nurture first-class business leaders and foster academic and relevant research to serve the needs of Hong Kong, China and the rest of the world in the new Asia-led economy. As Asia's premier international business school, FBE engages leading scholars from all corners of the globe and they instil in the students global knowledge with an Asian perspective. The Faculty attracts top students from Hong Kong and beyond. It admits the highest proportion of non-local undergraduate students amongst all Faculties at HKU. Three of its undergraduate programmes are ranked among the University's top 10 programmes. The Faculty's full-time MBA programme has a strong Asia and China focus, and the programme has been ranked Asia's no. 1 in the World MBA Rankings released by the Economist Intelligence Unit (EIU) for seven consecutive years from 2010 to 2016. Students can opt for an overseas exchange opportunity to supplement their campus learning in Hong Kong: a London track at London Business School, a New York track at Columbia Business School or a Hong Kong/China track at Fudan University. The Faculty also offers an elite EMBA Global Asia programme, jointly with CBS and LBS, for globally-focused senior executives and professionals. Its International MBA Programme, delivered in Shanghai in collaboration with Fudan University, was the first of its kind when it was launched in 1998. FBE is fully accredited by the European Quality Improvement Systems (EQUIS). Its accounting and business programmes are also accredited by the Association to Advance Collegiate Schools of Business (AACSB). About the Shenzhen Academy of Social Science Established in July 1992, the Shenzhen Academy of Social Science (SZASS) is a subordinate unit of the Shenzhen Municipal People's Government. SZASS is a research institute of philosophy and social science, consisting of five research units: economy, social development, culture, political science and law, and international urban studies. More information is available at: www.szass.com.

Fox P.T.,Research Imaging Institute and | Fox P.T.,University of Texas Health Science Center at San Antonio | Fox P.T.,South Texas Veterans Health Care System | Fox P.T.,University of Hong Kong | And 4 more authors.
Annual Review of Neuroscience | Year: 2014

Spatial normalization-applying standardized coordinates as anatomical addresses within a reference space-was introduced to human neuroimaging research nearly 30 years ago. Over these three decades, an impressive series of methodological advances have adopted, extended, and popularized this standard. Collectively, this work has generated a methodologically coherent literature of unprecedented rigor, size, and scope. Large-scale online databases have compiled these observations and their associated meta-data, stimulating the development of meta-analytic methods to exploit this expanding corpus. Coordinate-based meta-analytic methods have emerged and evolved in rigor and utility. Early methods computed cross-study consensus, in a manner roughly comparable to traditional (nonimaging) meta-analysis. Recent advances now compute coactivation-based connectivity, connectivity-based functional parcellation, and complex network models powered from data sets representing tens of thousands of subjects. Meta-analyses of human neuroimaging data in large-scale databases now stand at the forefront of computational neurobiology. © Copyright ©2014 by Annual Reviews. All rights reserved.

Yeung M.L.,University of Hong Kong | Jeang K.-T.,National Institute of Allergy and Infectious Diseases
Pharmaceutical Research | Year: 2011

MicroRNAs (miRNAs) are small physiological non-coding RNAs that regulate gene expression through an RNA interference (RNAi) mechanism. The expression of miRNAs is tightly controlled both spatially and temporally. Aberrant miRNA expression has been correlated with various cancers. Recent findings suggest that some miRNAs can function as tumor suppressors or oncogenes. In model experiments, the cancer phenotype of some cells can be reverted to normal when the cells are treated with miRNA mimics or inhibitors. Here, we discuss in brief the potential utility of miRNA-based cancer therapy as well as the current limitations thwarting their useful clinical application. © 2011 Springer Science + Business Media, LLC (outside the USA).

Sha W.E.I.,University of Hong Kong | Choy W. C. H.,University of Hong Kong | Chew W.C.,University of Illinois at Urbana - Champaign
Optics Express | Year: 2010

A comprehensive study of the plasmonic thin-film solar cell with the periodic strip structure is presented in this paper. The finite-difference frequency-domain method is employed to discretize the inhomogeneous wave function for modeling the solar cell. In particular, the hybrid absorbing boundary condition and the one-sided difference scheme are adopted. The parameter extraction methods for the zeroth-order reflectance and the absorbed power density are also discussed, which is important for testing and optimizing the solar cell design. For the numerical results, the physics of the absorption peaks of the amorphous silicon thin-film solar cell are explained by electromagnetic theory; these peaks correspond to the waveguide mode, Floquet mode, surface plasmon resonance, and the constructively interference between adjacent metal strips. The work is therefore important for the theoretical study and optimized design of the plasmonic thin-film solar cell. © 2010 Optical Society of America.

Su H.,Huazhong University of Science and Technology | Chen M.Z.Q.,University of Hong Kong | Wang X.,Shanghai JiaoTong University | Lam J.,University of Hong Kong
IEEE Transactions on Industrial Electronics | Year: 2014

This paper studies the observer-based leader-following consensus of a linear multiagent system on switching networks, in which the input of each agent is subject to saturation. Based on a low-gain output feedback method, distributed consensus protocols are developed. Under the assumptions that the networks are connected or jointly connected and that each agent is asymptotically null controllable with bounded controls and detectable, semiglobal observer-based leader-following consensus of the multiagent system can be reached on switching networks. A numerical example is presented to illustrate the theoretical results. © 1982-2012 IEEE.

Shiau W.-L.,Ming Chuan University | Chau P.Y.K.,University of Hong Kong
Industrial Management and Data Systems | Year: 2012

Purpose: The purpose of this paper is to understand blog continuance. Specifically, this paper aims to compare two theoretical models and an integrated model to identify which theoretical models best predicts blog continuance intention. Design/methodology/approach: An empirical study was conducted through an online survey. Data collected from six famous blogs in Taiwan (n = 361) were analyzed using structural equation modeling and pairwise nested F-tests. Findings: Results show that the ECT-IS model and the integrated model have greater explanatory power of blog continuance intention than the technology acceptance model (TAM). The results of pairwise nested F-tests show that the ECT-IS model exhibits statistically significant R 2 improvement compared to TAM. However, the R 2 improvement in the integrated model is not statistically different from that in the ECT-IS model. The ECT-IS model is also more parsimonious than the integrated model. Thus, the ECT-IS is a preferable model. Confirmation and satisfaction are salient factors influencing this intention. Practical implications - The results of this study provide useful information for blogging service providers (BSPs) to enhance and develop useful blog functions for user satisfaction. By revealing the differences and comparisons among these three models, this study can help BSPs promote the benefits of their blogs to strengthen the continuance intentions of their customers. Originality/value: This paper is one of the first studies to examine of influence change of variables and compare the relative ability of two competing theories, ECT-IS and TAM, and an integrated model in explaining blog continuance intention. The results confirm that the ECT-IS is a better model than the other two for explaining blog continuance intention. © Emerald Group Publishing Limited.

Li B.,University of Hong Kong | Li B.,University of Wollongong | Li S.-H.,University of Hong Kong
Quaternary Geochronology | Year: 2012

A multi-elevated-temperature post-IR IRSL (MET-pIRIR) protocol, which utilizes the IRSL signals measured by progressively increasing the stimulation temperature from 50 to 300 °C in a step of 50 °C, was applied to date the potassium-rich feldspar (K-feldspar) extracts from loess samples at the Luochuan section of the Chinese Loess Plateau. It was observed that the MET-pIRIR ages obtained at elevated-temperatures (250 and 300 °C) are consistent with independent chronological control for the samples from the first loess layer (L1) to the third paleosol layer (S3), which correspond to the marine isotope stages (MIS) 2-9. Our results indicate that the MET-pIRIR protocol can provide reliable ages for the Chinese loess up to ∼300 ka. The results suggest that the MET-pIRIR signal measured at 250 and 300 °C gives the most reliable ages for older samples (>130 ka). For samples below L3, the natural MET-pIRIR signals measured at high temperatures reach the saturation level in dose response curves, suggesting a dating limit of ∼300 ka for the Luochuan loess section. © 2012 Elsevier B.V.

Liu X.,University of Pennsylvania | Jin D.-Y.,University of Hong Kong | McManus M.T.,University of California at San Francisco | Mourelatos Z.,University of Pennsylvania
Molecular Cell | Year: 2012

Assembly of microRNA ribonucleoproteins (miRNPs) or RNA-induced silencing complexes (RISCs) is essential for the function of miRNAs and initiates from processing of precursor miRNAs (pre-miRNAs) by Dicer or by Ago2. Here, we report an in vitro miRNP/RISC assembly assay programmed by pre-miRNAs from mammalian cell lysates. Combining in vivo studies in Dicer Knockout cells reconstituted with wild-type or catalytically inactive Dicer, we find that the miRNA loading complex (miRLC) is the primary machinery linking pre-miRNA processing to miRNA loading. We show that a miRNA precursor deposit complex (miPDC) plays a crucial role in Dicer-independent miRNA biogenesis and promotes miRNP assembly of certain Dicer-dependent miRNAs. Furthermore, we find that 5'-uridine, 3'-mid base pairing, and 5'-mid mismatches within pre-miRNAs promote their assembly into miPDC. Our studies provide a comprehensive view of miRNP/RISC assembly pathways in mammals, and our assay provides a versatile platform for further mechanistic dissection of such pathways in mammals. © 2012 Elsevier Inc.

Chen J.-C.,CAS Institute of Physics | Wang J.,University of Hong Kong | Sun Q.-F.,CAS Institute of Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

The effect of magnetic field on electron transport in the inverted band structure of HgTe/CdTe quantum well is investigated. Although magnetic field breaks the time-reversal symmetry, the quantum spin Hall effect can still survive at large magnetic field up to 10 T. Moreover, two quantum anomalous Hall-like phases emerge, in which the system only has a spin-up or spin-down edge state at a given sample edge and the edge current is spin polarized. By tuning the Fermi energy, the system can transit between the quantum spin Hall phase and two quantum anomalous Hall-like phases, so the polarized direction of the edge current is well controllable. Thus the spin selectivity can be realized for potential applications of spintronics. Due to the quantum spin and anomalous Hall-like effects, the longitudinal and Hall resistances exhibit quantum plateaus. In addition, at certain magnetic field, some exotic plateaus like 23 fractional quantum Hall effect are also observed, where edge states with the same spin counterpropagate at the one edge. At last, these plateaus are hardly affected by Rashba spin-orbit interaction, Zeeman effect, and Anderson disorder. © 2012 American Physical Society.

Xiao D.,Oak Ridge National Laboratory | Liu G.-B.,University of Hong Kong | Feng W.,Oak Ridge National Laboratory | Feng W.,University of Tennessee at Knoxville | And 3 more authors.
Physical Review Letters | Year: 2012

We show that inversion symmetry breaking together with spin-orbit coupling leads to coupled spin and valley physics in monolayers of MoS 2 and other group-VI dichalcogenides, making possible controls of spin and valley in these 2D materials. The spin-valley coupling at the valence-band edges suppresses spin and valley relaxation, as flip of each index alone is forbidden by the valley-contrasting spin splitting. Valley Hall and spin Hall effects coexist in both electron-doped and hole-doped systems. Optical interband transitions have frequency-dependent polarization selection rules which allow selective photoexcitation of carriers with various combination of valley and spin indices. Photoinduced spin Hall and valley Hall effects can generate long lived spin and valley accumulations on sample boundaries. The physics discussed here provides a route towards the integration of valleytronics and spintronics in multivalley materials with strong spin-orbit coupling and inversion symmetry breaking. © 2012 American Physical Society.

Li J.,University of Hong Kong | Soh A.K.,Sunway University
Acta Materialia | Year: 2013

An attempt has been made to illustrate a new physical mode of plastic deformation in nanocrystalline materials that synergizes two processes, i.e. grain boundary (GB) sliding and stress-driven shear-coupled GB migration. The latter process incorporates a rotational and a translational plastic flow, in which a normal migration is coupled with a shear. The energy change resulting from the above-mentioned mode was calculated, and showed that the new deformation mode was much more energetically favorable than both the pure GB sliding mode and the cooperative process of GB sliding and migration without a coupling shear. In addition, the new deformation mode considerably enhances the ductility of nanocrystalline materials compared with the other two above-mentioned processes. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Romero-Canelon I.,University of Warwick | Sadler P.J.,University of Warwick | Sadler P.J.,University of Hong Kong
Inorganic Chemistry | Year: 2013

Platinum complexes are widely used anticancer drugs. New generations of metal chemotherapeutics offer the prospect of combating platinum resistance and expanding the range of treatable cancers. Such new complexes might be effective if they form distinctly different lesions on DNA. In this Forum Article, we discuss the possibility that targeting the redox balance in cancer cells may also be a highly effective strategy, especially because it is a multiple-site approach and offers selectivity over normal cells. Metal complexes can interfere in cellular redox chemistry in several ways: directly through metal or ligand redox centers or indirectly by binding to biomolecules involved in cellular redox pathways. We illustrate that a surprisingly large number of active metal anticancer agents have a potential redox arm to their mechanism of action. For such complexes, the possibility arises of using combination therapy together with redox modulators to increase the anticancer potency: attractive for lowering the doses of metal complexes that need to be administered. We illustrate that organometallic ruthenium(II) and osmium(II) arene complexes and iridium(III) cyclopentadienyl complexes of the type [(arene/Cp xPh)M(N,N)Cl/I]n+ can achieve nanomolar potency toward cancer cells in combination with the redox modulator l-buthionine sulfoximine. Our discussion highlights the importance of determining not only the distribution of metal anticancer complexes in cells but also their speciation, the chemical form of the metal complex, including the oxidation state of the metal, the fate of the ligands, and dynamic processes such as efflux. This will be aided in the future by proteomic and genomic analyses but needs to be supplemented by new analytical methods that have the sensitivity and spatial and temporal resolution to reveal such information. To achieve this, major new funding programs are needed that support global research on the design of novel metal-based drugs with new mechanisms of action, tailored to patient needs. © 2013 American Chemical Society.

Agency: Cordis | Branch: FP7 | Program: CP-IP | Phase: HEALTH-2009-2.2.1-2 | Award Amount: 15.03M | Year: 2010

The aim of EU-GEI is to identify the interactive genetic, clinical and environmental determinants involved in the development, severity and outcome of schizophrenia (EU-GEI, Schiz. Res. 2008; 102: 21-6). In order to identify these interactive determinants, EU-GEI will employ family-based, multidisciplinary research paradigms, which allow for the efficient assessment of gene-environment interactions. In order to go beyond old findings from historical convenience cohorts with crude measures of environmental factors and clinical outcomes, the focus in EU-GEI will be on recruitment of new, family-based clinical samples with state-of-the-art assessments of environmental, clinical and genetic determinants as well as their underlying neural and behavioural mechanisms. New statistical tools will be developed to combine the latest multilevel epidemiological with the latest genome-wide genetic approaches to analysis. Translation of results to clinical practice will be facilitated by additional experimental research and risk assessment bioinformatics approaches. This will result in the identification of modifiable biological and cognitive mechanisms underlying gene-environment interactions and the construction of Risk Assessment Charts and Momentary Assessment Technology tools which can be used for (i) early prediction of transition to psychotic disorder in help-seeking individuals with an at-risk mental state and (ii) early prediction of course and outcome after illness onset. In order to reach these goals, EU-GEI has assembled a multidisciplinary team of top schizophrenia researchers who have the range of skills required to deliver a program of research that meets all the calls requirements and who have access to / will collect a number of unique European samples. The partners in EU-GEI represent the nationally funded schizophrenia / mental health networks of the UK, Netherlands, France, Spain, Turkey and Germany as well as other partners.

Agency: GTR | Branch: NERC | Program: | Phase: Research Grant | Award Amount: 381.35K | Year: 2014

The sensitivity of global climate to increasing atmospheric carbon dioxide (CO2) levels is one of the biggest issues currently facing humanity. Quantifying the sensitivity of the Earths climate system to changes in CO2 levels in the geologic past is one way of reducing the uncertainty in future climate predictions. If man-made (anthropogenic) CO2 emissions to the atmosphere follow projected rates, by 2100 concentrations will reach values not seen on Earth since the Oligocene epoch ~23 to 34 million years ago (Ma). Back then, geologists infer that Earth was warmer than today, featuring a genuinely green Greenland and a waxing and waning East Antarctic Ice Sheet (EAIS) that drove high amplitude sea level change (~40 m). These startling observations provide a powerful incentive to improve our understanding of the workings of that past climate system. The focus of this proposal is on an important, but understudied, interval of time (~26 to 28 Ma) for which published palaeoclimate records indicate the biggest repeated (100 thousand-year time scale) changes in Antarctic ice volume and high-latitude temperatures of the entire Oligocene epoch. Our proposed study will generate geological data to both test this interpretation of Oligocene high-latitude climate instability and further elucidate the nature of ice-sheet and temperature variability. Validation of the existence of dynamic Antarctic ice sheets, however, would present a major scientific problem because numerical analysis of ice sheet behavior suggests that, in the absence of big changes in CO2 levels, a large Antarctic ice sheet should be stable once formed because of strong hysteresis properties associated with ice sheet geometry. Several important questions are therefore raised: 1. How resilient were the early Antarctic ice sheets to CO2 change? 2. Do the numerical models give a false sense of the stability of both the Oligocene and, by extension, present day East Antarctic Ice Sheet? 3. Was Oligocene CO2 variability much greater than indicated in existing reconstructions? 4. Is it possible that ice sheets existed beyond Antarctica during the Oligocene? The main factor that has limited progress in tackling these questions has been a lack of suitable sedimentary sections on which to work. We propose to exploit new deep-sea sediment archives recovered from the Antarctic and Newfoundland margins during Integrated Ocean Drilling Program Expeditions 318 and 342, respectively, on which our investigator team played significant roles (see Part 1, Case for Support). Our project will use (i) the Antarctic cores to test for the erosive products of dynamic behaviour (advance and retreat) on the East Antarctic margin, and (ii) the Newfoundland cores to test if high-latitude climatic conditions in the Northern Hemisphere were conducive to ice-sheet growth. Intriguingly, the drill cores from the Newfoundland margin contain abundant conspicuous angular sand sized lithic fragments that have been interpreted to be of ice-rafted origin-hinting at the presence of some form of nearby ice in the Oligocene. Our work will be accomplished through novel investigation of detrital isotope geochemistry on the Antarctic margin and application of organic geochemical temperature proxies in the high-latitude North Atlantic. Critical to our approach will be generation of high-resolution datasets that can be precisely dated and correlated to one another, as well as other high-resolution datasets around the globe.

News Article | November 2, 2016
Site: www.eurekalert.org

A study led by Dr K.C. Tan-Un and her team at the School of Biological Sciences, the University of Hong Kong (HKU), in collaboration with Professor Richard Festenstein at the Clinical Sciences Centre, Imperial College London, and Professor Sjaak Phillipsen at Erasmus University, Rotterdam, have discovered a crucial part of the genetic machinery that switches on the Neuroglobin gene. This discovery opens up a new opportunity in treating Alzheimer's disease (AD), such with the development of gene therapy. The study was published recently in the journal Nucleic Acids Research. Neuroglobin has previously been shown to protect the brain of mice and is shown to reduce the severity of damage due to stroke and AD. In human, it is observed that the two major risk factors of AD, age and female sex are associated with lower levels of Neuroglobin. Identifying the "switch" for the neuroglobin gene is therefore of paramount importance, as it will serve as a potential target for the development of novel therapeutic treatments with gene therapy or drugs. AD currently affects more than 70,000 people in Hong Kong and the number is estimated to reach 280,000 in 20 years because of the aging population. Currently the disease is incurable, thus there is an urgent need to find a treatment for the disease. Since the discovery of the neuroglobin gene in 2000, studies have focused on its functions, yet little is known about how the gene is being regulated. The HKU team spent 6 years addressing the mechanism that controls the switching of the Neuroglobin gene. Dr. Tan-Un at HKU led the study with the hypothesis that there is a "switch" that controls the expression of the neuroglobin gene which is located far away from the gene itself. The search of the distal DNA region has been technically challenging and the idea was tested by a series of experiments, carried out by two former PhD students, namely, Tam Kin-tung and Zhang Wei, including a technique called chromosome conformation capture (3C). The research team found that there is a segment of DNA which interacts with the Neuroglobin gene by means of a protein called GATA-2 in human neuronal cells. The results showed that the novel DNA segment is powerful in switching on Neuroglobin expression. Removal of either GATA-2 protein or the DNA segment from the cells led to a substantial decrease in Neuroglobin expression. Professor Godfrey Chi-Fung Chan, a co-author from the Department of Paediatrics and Adolescent Medicine, HKU, said: "AD is an incurable disease at the moment and understanding the control mechanism of an important protector in the neural tissue such as Neuroglobin will provide us with a new therapeutic strategy. In fact, the role of neuroglobin is not confined to degenerative brain disorders, its aberrant role in neurogenic neoplasms is another interesting area to be explored. Therefore knowing how to 'switch on' or 'switch off' this molecule will help us to modulate a variety of human diseases." The discovery of the Neuroglobin switch opens up new opportunities in treating AD, such as the development of gene therapy. To effectively increase the expression of Neuroglobin to protect the brain, the gene together with the newly identified switch may be inserted into the genome. GATA-2 protein may also be manipulated by drugs to induce Neuroglobin expression. As the increase in neuroglobin expression is protective for AD, the team's future research will focus on the identification of factors that will enhance the "switch" mechanism of neuroglobin in brain. Dr. Tan-Un highlighted: "Further understanding this 'switch' and neuroglobin locus will be crucial in the design of efficient gene therapy system for the treatment of Alzheimer's disease and other neurodegenerative diseases." The article "Identification of a novel distal regulatory element of the human Neuroglobin gene by the chromosome conformation capture approach" published recently in the journal Nucleic Acids Research* can be obtained from the following link: *Nucleic Acids Research ranks within the top 6% of Biochemistry and Molecular Biology journals

News Article | November 22, 2016
Site: www.24-7pressrelease.com

NEW YORK, NY, November 22, 2016-- Dr. Henry Pan has been included in Marquis Who's Who. As in all Marquis Who's Who biographical volumes, individuals profiled are selected on the basis of current reference value. Factors such as position, noteworthy accomplishments, visibility, and prominence in a field are all taken into account during the selection process.Dr. Pan arrived in the United States in 1969 upon completion of a Bachelor of Science degree in genetics from McGill University in Montreal, Canada, to pursue graduate studies at the University of Hawaii with the late Professor Louis Casarett, a world renowned inhalation toxicologist. Dr. Pan graduated with a Master of Science in toxicology and later a Ph.D. in molecular pharmacology from the University of Hawaii. While at the University, he was both a research and teaching assistant. Following his graduate degrees, Dr. Pan entered medical school and graduated in 1979 from the University of Hong Kong, School of Medicine. Upon graduation, Dr. Pan entered the field as a medical officer at Queen Mary Hospital from 1979 to 1981, and was a tenured assistant professor of medicine and clinical pharmacology at the University of Hong Kong from 1981 to 1985.Dr. Pan returned to the United States in 1983 as a fellow in clinical pharmacology and a visiting professor of medicine at Stanford University, School of Medicine. This marked the beginning of an impressive three decades of field work in research, administrative, directorial, and chief operating roles in executive positions. Ten years' worth of healthcare and medicinal knowledge and extensive research skills developed both in the classroom and the hospital opened the doors to a myriad of opportunities. Dr. Pan has been the vice president of clinical research and development at the Bristol Myers Squibb Company; the executive vice president of drug development and medical affairs at the DuPont Merck Pharmaceutical Company; the president and CEO of MDS Pharmaceutical Services; chief executive officer of Vennworks RTP; the executive vice president and chief medical officer of Neurocrine Biosciences Inc.; and the executive vice president and chief scientific and medical officer of Prometheus Laboratories Inc., among other positions. His current positions include the chief executive officer of Renascions Inc. and Renascions Biopharma Inc., and the chief executive of Pan Consulting Associates LLC, where he provides consulting services to North American, European, and Asian biopharmaceutical companies.Dr. Pan has been inducted as a fellow in multiple prestigious organizations: the American College of Cardiology, the American College of Clinical Pharmacology, the American Heart Association, the American Society of Angiology, the Institute of Biological and Clinical Investigation, the Academy of Medicine of New Jersey, and the Faculty of Pharmaceutical Medicine of the Royal College of Physicians in the UK. He has served on the board of 15 companies and was the chairman of the biopharmaceutical division of the Society of Chinese Bioscientists in America, one of the largest minority science organizations in the United States.For his contributions to the medical field, Dr. Pan has been included in the 47th through 50th, 52nd through 57th, 59th through 61st, 63rd, and the 67th through 70th editions of Who's Who in America; the 2nd through 6th editions of Who's Who in Medicine and Healthcare; the 1st through 6th editions of Who's Who in Science and Engineering; the 23rd through 28th editions of Who's Who in the East; the 16th through 25th editions of Who's Who in the World; and the 4th edition of Who's Who of Emerging Leaders in America.About Marquis Who's Who :Since 1899, when A. N. Marquis printed the First Edition of Who's Who in America , Marquis Who's Who has chronicled the lives of the most accomplished individuals and innovators from every significant field of endeavor, including politics, business, medicine, law, education, art, religion and entertainment. Today, Who's Who in America remains an essential biographical source for thousands of researchers, journalists, librarians and executive search firms around the world. Marquis now publishes many Who's Who titles, including Who's Who in America , Who's Who in the World , Who's Who in American Law , Who's Who in Medicine and Healthcare , Who's Who in Science and Engineering , and Who's Who in Asia . Marquis publications may be visited at the official Marquis Who's Who website at www.marquiswhoswho.com

News Article | September 19, 2016
Site: cen.acs.org

Water-stressed communities from California to Singapore have begun reclaiming wastewater for drinking and other uses, but they face a challenge: It’s hard for the treatment process to remove trace organic pollutants, such as endocrine disruptors. Now researchers have developed a potential solution, coating a commonly used filtration membrane with a material that rejects endocrine-disrupting molecules (Environ. Sci. Technol. Lett. 2016, DOI: 10.1021/acs.estlett.6b00263). Many of the commercially available nanofiltration and reverse osmosis membranes currently used to clean wastewater were optimized for desalination. They’re made with a relatively hydrophobic polyamide composite that rejects salt and other ions. Since many endocrine disruptors, such as bisphenol A (BPA) and parabens, are also hydrophobic, these compounds tend to stick to the membrane and can eventually diffuse through to the other side (Environ. Sci. Technol. 2004, DOI: 10.1021/es034952r). Chuyang Y. Tang of the University of Hong Kong and his colleagues thought that adding a hydrophilic coating to the membranes might prevent this problem. They tested their hunch with polydopamine, a thin hydrophilic coating researchers are exploring as a way to prevent membrane fouling in wastewater treatment. The researchers coated a commercial polyamide-based nanofiltration membrane, NF90, by shaking it with a solution of dopamine hydrochloride for up to four hours; the dopamine self-polymerizes on the membrane surface. Then they tested the system’s performance in filtering water containing four endocrine disruptors: ethylparaben, propylparaben, benzylparaben, and BPA, at 200 μg/L, which is comparable to or higher than their average concentration in wastewater. The coated membrane rejected 60 to 70% of the three paraben compounds tested, whereas the untreated membrane rejected 35 to 50%. BPA rejection improved from 96% for the uncoated membrane to 99% for the coated version. However, the four-hour coating also lowered the membrane’s water permeability by 45%, which Tang says is too much to be practical and something his team wants to improve—a 10% reduction would be more “bearable” for application. Recently, they developed a more hydrophilic coating material that can be applied in very thin layers, minimizing the adverse effect on membrane permeability yet maintaining rejection of endocrine disruptors, according to their preliminary results. What’s more, this approach shortens the coating time from hours to minutes, “an important consideration for industrial upscaling,” Tang says. Long Nghiem, a membrane engineer at the University of Wollongong, praises the team’s “elegant but simple approach,” while noting that it is a proof-of-concept study. He says the researchers must next assess the impact of the coating on membrane fouling.

News Article | October 23, 2015
Site: news.mit.edu

MIT engineers have devised a way to rapidly test hundreds of different drug-delivery vehicles in living animals, making it easier to discover promising new ways to deliver a class of drugs called biologics, which includes antibodies, peptides, RNA, and DNA, to human patients. In a study appearing in the journal Integrative Biology, the researchers used this technology to identify materials that can efficiently deliver RNA to zebrafish and also to rodents. This type of high-speed screen could help overcome one of the major bottlenecks in developing disease treatments based on biologics: It is challenging to find safe and effective ways to deliver them. “Biologics is the fastest growing field in biotech, because it gives you the ability to do highly predictive designs with unique targeting capabilities,” says senior author Mehmet Fatih Yanik, an associate professor of electrical engineering and computer science and biological engineering. “However, delivery of biologics to diseased tissues is challenging, because they are significantly larger and more complex than conventional drugs.” “By combining this work with our previously published high-throughput screening system, we are able to create a drug-discovery pipeline with efficiency we had never imagined before,” adds Tsung-Yao Chang, a recent MIT PhD recipient and one of the paper’s lead authors. Peng Shi, a former MIT postdoc who is now an assistant professor at the University of Hong Kong, is the paper’s other lead author. Zebrafish are commonly used to model human diseases, in part because their larvae are transparent, making it easy to see the effects of genetic mutations or drugs. In 2010, Yanik’s team developed a technology for rapidly moving zebrafish larvae to an imaging platform, orienting them correctly, and imaging them. This kind of automated system makes it possible to do large-scale studies because analyzing each larva takes less than 20 seconds, compared with the several minutes it would take for a scientist to evaluate the larvae by hand. For this study, Yanik’s team developed a new technology to inject RNA carried by nanoparticles called lipidoids, previously designed by Daniel Anderson, an associate professor of chemical engineering, member of the Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science, and an author of the new paper. These fatty molecules have shown promise as delivery vehicles for RNA interference, a process that allows disease-causing genes to be turned off with small strands of RNA. Yanik’s group tested about 100 lipidoids that had not performed well in tests of RNA delivery in cells grown in a lab dish. They designed each lipidoid to carry RNA expressing a fluorescent protein, allowing them to easily track RNA delivery, and injected the lipidoids into the spinal fluid of the zebrafish. To automate that process, the zebrafish were oriented either laterally or dorsally once they arrived on the viewing platform. Once the larvae were properly aligned, they were immobilized by a hydrogel. Then, the lipidoid-RNA complex was automatically injected, guided by a computer vision algorithm. The system can be adapted to target any organ, and the process takes about 14 seconds per fish. A few hours after injection, the researchers imaged the zebrafish to see if they displayed any fluorescent protein in the brain, indicating whether the RNA successfully entered the brain tissue, was taken up by the cells, and expressed the desired protein. The researchers found that several lipidoids that had not performed well in cultured cells did deliver RNA efficiently in the zebrafish model. They next tested six randomly selected best- and worst-performing lipidoids in rats and found that the correlation between performance in rats and in zebrafish was 97 percent, suggesting that zebrafish are a good model for predicting drug-delivery success in mammals. “The ability to identify useful drug delivery nanoparticles using this miniaturized system holds great potential for accelerating our discovery process,” Anderson says. “The lipidoid material screen is just an example demonstrated in this article; a similar strategy can be readily extended to other libraries or other organ systems,” Peng adds. Jeff Karp, an associate professor of medicine at Harvard Medical School who was not part of the research team, says this work is “an excellent example of harnessing a multidisciplinary team to partner complementary technologies for the purpose of solving a unified problem. Yanik and colleagues, who have extensive expertise with high-throughput screening in zebrafish and other small animals, have teamed up with Anderson et al., who are leading experts in RNA delivery, to create a new platform for rapidly screening biologics and methods to deliver them. This approach should have utility across multiple disease areas.” The researchers are now using what they learned about the most successful lipidoids identified in this study to try to design even better possibilities. “If we can pick up certain design features from the screens, it can guide us to design larger combinatorial libraries based on these leads,” Yanik says. Yanik’s lab is currently using this technology to find delivery vehicles that can carry biologics across the blood-brain barrier — a very selective barrier that makes it difficult for drugs or other large molecules to enter the brain through the bloodstream. The research was funded by the National Institutes of Health, the Packard Award in Science and Engineering, Sanofi Pharmaceuticals, Foxconn Technology Group, and the Hertz Foundation.

News Article | December 7, 2016
Site: www.eurekalert.org

New moms are increasingly using expressed breast milk (either pumped or expressed by hand) instead of directly breastfeeding their babies, according to a UBC study. The study also found that moms who use expressed breast milk typically transition their babies to infant formula feeding sooner than their breastfeeding peers, a trend that may impact the health of our next generation. "Breast feeding is the unequalled method for feeding infants," says Marie Tarrant, director of nursing at UBC's Okanagan campus. "It has been previously determined that breastfeeding is important for the nutrition, immunology, growth and development of infants and toddlers. Anything that contributes to shortening the recommended six months of exclusive breastfeeding is a concern." Tarrant and her research team, including co-author Dorothy Bai of the University of Hong Kong, studied the infant feeding practices of more than 2,000 moms living in Hong Kong. They found that during a five-year stretch, mothers moved away from directly breastfeeding their infants to using expressed breast milk, which is usually delivered via a bottle. "New mothers may believe there is no difference between expressed breast-milk feeding and direct feeding at the breast," says Tarrant. "Although expressed breast-milk feeding provides greater benefits than infant formula, bottle-feeding may increase the risk of respiratory issues, asthma, rapid weight gain and oral diseases." The study demonstrated that those moms who expressed breast milk were more likely to quit breastfeeding earlier than moms who directly breastfed. Tarrant believes that a lack of breastfeeding support may be partly to blame for this feeding behaviour. She suggests that providing greater access to professional lactation (breastfeeding) support to new mothers, particularly in the first 24 hours after birth, could ensure that new infants receive the optimal nutrition. According to Stats Canada, there were more than 350,000 Canadian babies born in 2015/2016. In 2012, 89 per cent of women initially breastfed their babies, and only 26 per cent were doing so six months later. Difficulty with breastfeeding is the most common reasons for not continuing with the practice. The study, recently published in Public Health Nutrition, was funded by the Health and Medical Research Fund, Government of the Hong Kong Special Administrative Region.

News Article | November 22, 2016
Site: www.eurekalert.org

Health-care professionals are hesitant to administer the flu vaccine to pregnant women, despite the potential life-saving benefits, according to a UBC study. The study also shows that pregnant women who were eager to get vaccinated had difficulties because health professionals turned them away. "The World Health Organization and Health Canada have classified pregnant women as one of the highest at-risk groups of having serious complications following influenza infection," says Marie Tarrant, director of nursing at UBC's Okanagan campus. "Given this, the health-care community should work together to protect these moms and their infants. Flu vaccination is one of the best ways." Tarrant and her team, including co-author Valerie Wong of the University of Hong Kong, embarked on a research campaign to assess the effect of a brief flu vaccination education program targeted to pregnant women. The study was conducted in Hong Kong where vaccination rates are particularly low and there are two flu seasons. The researcher found that one-to-one education interventions significantly increased vaccination rates yet the uptake was still low. Upon follow-up with the women, they discovered that some doctors refused to vaccinate or that the vaccines were unavailable. "Even with the knowledge of benefits of vaccination, there still is this long-held belief that pregnant women should minimize exposing the fetus to any unknown substance, especially those injected into the body," says Tarrant. "I believe this reluctance is common worldwide." "Targeted interventions to health-care professionals and enhanced maternal education may help to address concerns and fears about flu vaccination, and lead to optimal and improved vaccination coverage." The flu is a respiratory infection caused by influenza viruses. Canadians typically contract the flu during the late fall and winter. Symptoms may include high fever, chills, sore throat, cough and tiredness. Most people recover within a week but some, including pregnant women, the very young and those over 65 years old, are at increased risk for severe complications. Globally, annual epidemics result in an about one billion cases of influenza, three to five million cases of severe illness, and 250,000 to 500,000 deaths. Almost 30 per cent of Canadians were vaccinated against the flu last year. This is substantially below Health Canada's target of 80 per cent. The study, recently published in Vaccine, was funded by the Health and Medical Research Fund, Government of the Hong Kong Special Administrative Region.

News Article | November 2, 2016
Site: www.eurekalert.org

Professor Ron Hui, Chair Professor of Power Electronics and Philip Wong Wilson Wong Professor of Electrical Engineering at the University of Hong Kong, has been named a Fellow by the Royal Academy of Engineering, U.K., one of the most prestigious national academies. Professor Hui attended the New Fellow Induction ceremony in London on October 20 (Thursday, HKT). The ceremony was officiated by HRH The Prince Philip, Duke of Edinburgh and Senior Fellow of the Academy. The citation for Professor Hui stated: "Professor Hui is a visionary inventor and researcher. His groundbreaking research focuses on power electronics, with emphasis on energy saving and reduction of electronic waste. His achievements involve fundamental engineering science and applications, influencing both academic and industrial worlds." Professor Hui was delighted to receive the honour, he said: "I am deeply honoured being named a Fellow of the Academy, in recognition of my research in environmentally friendly and sustainable technologies. More importantly, it serves as important recognition of research efforts which help protect the Earth and its sustainability in the long run, for the well-being of our next generations. I am in particular grateful in this regard." Over the last 20 years, Professor Ron Hui has focused his research on environmentally friendly technologies. His ground-breaking research focuses on Power Electronics, with emphasis on energy saving and reduction of electronic waste. Besides publishing extensively in top-tier research journals in power electronics, he has over 55 patents adopted by industry. His achievements Planar Wireless Power Transfer and Sustainable Lighting Technology have been previously recognised by the Institute of Electical & Electronic Engineers (IEEE) USA, Institution of Engineering & Technology (IET) UK and the Australian Academy of Technological Sciences & Engineering. Professor Hui's inventions have underpined the key features of the World's 1st Wireless Power Standard "Qi", launched by the international Wireless Power Consortium (WPC) in 2010. Noting the surge of mobile phone chargers and their e-waste problem in early 2000's, he has pioneered a series of "Planar Wireless Charging technologies" covering (i) free-positioning, (ii) localized charging and (iii) load identification. Such user-friendly technologies have been adopted into "Qi" by the WPC, now comprising over 200 companies worldwide. Professor Hui raised the electronic waste issues arising from electronic lighting products in early 2000. He has championed the concept of "Sustainable Lighting" that incorporates not only energy saving (as adopted in Energy Star), but also long product lifetime and recyclability of product components. He invented sustainable ballasts/drivers that outperform conventional ones with improved energy efficiency, lifetime and recyclability. He designed the world's first passive LED driver that has designed lifetime (>10 years) exceeding that of the LED devices. (now in production for street lighting). In 2009, he published the Photo-electro-thermal Theory for LED Systems, unifying the interactions of light, heat and power. Such theory has been adopted into the Industrial Electronics Handbook. Professor Hui's achievements in Planar Wireless Charging Technology have been independently recognised by both of IET (UK) and IEEE (USA) with their "most prestigious awards" in Power Research: 2010 The IET Crompton Medal for achievements in Power 2015 IEEE William E. Newell Power Electronics Award (IEEE Technical Field Award - the highest honour in Power Electronics by the IEEE Award Board) Moreover, he received the IEEE Rodulf Chope Research & Development Award (for Sustainable Lighting Technology) in 2010, and was honoured a Fellow of the Austrialian Academy of Technological Science and Engineering in the same year. Presently, Professor Hui and his team are engaged in several exciting research ideas. He is studying new omnidirectional wireless power transfer (for 3-dimensional wireless charging) and electric springs (for stabilizing power systems with increasing renewable energy generation).

Huang K.,University of Hong Kong | Larsson E.,Linköping University
IEEE Transactions on Signal Processing | Year: 2013

Far-field microwave power transfer (MPT) will free wireless sensors and other mobile devices from the constraints imposed by finite battery capacities. Integrating MPT with wireless communications to support simultaneous wireless information and power transfer (SWIPT) allows the same spectrum to be used for dual purposes without compromising the quality of service. A novel approach is presented in this paper for realizing SWIPT in a broadband system where orthogonal frequency division multiplexing and transmit beamforming are deployed to create a set of parallel sub-channels for SWIPT, which simplifies resource allocation. Based on a proposed reconfigurable mobile architecture, different system configurations are considered by combining single-user/multi-user systems, downlink/uplink information transfer, and variable/fixed coding rates. Optimizing the power control for these configurations results in a new class of multi-user power-control problems featuring the circuit-power constraints, specifying that the transferred power must be sufficiently large to support the operation of the receiver circuitry. Solving these problems gives a set of power-control algorithms that exploit channel diversity in frequency for simultaneously enhancing the throughput and the MPT efficiency. For the system configurations with variable coding rates, the algorithms are variants of water-filling that account for the circuit-power constraints. The optimal algorithms for those configurations with fixed coding rates are shown to sequentially allocate mobiles their required power for decoding in ascending order until the entire budgeted power is spent. The required power for a mobile is derived as simple functions of the minimum signal-to-noise ratio for correct decoding, the circuit power and sub-channel gains. © 1991-2012 IEEE.

Yu C.,Johnson Electric | Chau K.T.,University of Hong Kong
IEEE Transactions on Energy Conversion | Year: 2011

In this paper, a new type of memory motors, namely the dc-excited memory motor, is proposed and implemented. The concept of dc-excited memory is due to the nature that the magnetization level of permanent magnets (PMs) in the motor can be regulated by a temporary dc current pulse and be automatically memorized. Based on an outer-rotor doubly salient motor structure, the proposed dc-excited memory motor can offer effective and efficient online air-gap flux control. Hence, it possesses the advantages of mechanical robustness, high efficiency, and wide constant power operation region. Both simulation and experimentation are carried out to verify the validity of the proposed motor. © 2010 IEEE.

Huang K.,University of Hong Kong | Lau V.K.N.,Hong Kong University of Science and Technology
IEEE Transactions on Wireless Communications | Year: 2014

Microwave power transfer (MPT) delivers energy wirelessly from stations called power beacons (PBs) to mobile devices by microwave radiation. This provides mobiles practically infinite battery lives and eliminates the need of power cords and chargers. To enable MPT for mobile recharging, this paper proposes a new network architecture that overlays an uplink cellular network with randomly deployed PBs for powering mobiles, called a hybrid network. The deployment of the hybrid network under an outage constraint on data links is investigated based on a stochastic-geometry model where single-antenna base stations (BSs) and PBs form independent homogeneous Poisson point processes (PPPs) with densities λ-b and λ-p, respectively, and single-antenna mobiles are uniformly distributed in Voronoi cells generated by BSs. In this model, mobiles and PBs fix their transmission power at p and q, respectively; a PB either radiates isotropically, called isotropic MPT, or directs energy towards target mobiles by beamforming, called directed MPT. The model is used to derive the tradeoffs between the network parameters (p, λ-b, q, λ-p) under the outage constraint. First, consider the deployment of the cellular network. It is proved that the outage constraint is satisfied so long as the product pλ-b^\frac{alpha}{2} is above a given threshold where α is the path-loss exponent. Next, consider the deployment of the hybrid network assuming infinite energy storage at mobiles. It is shown that for isotropic MPT, the product qλ-p λ-b^\frac{alpha}{2} has to be above a given threshold so that PBs are sufficiently dense; for directed MPT, z-mqλ-p λ-b^\frac{alpha}{2} with z-m denoting the array gain should exceed a different threshold to ensure short distances between PBs and their target mobiles. Furthermore, similar results are derived for the case of mobiles having small energy storage. © 2002-2012 IEEE.

Rowell C.,Hong Kong University of Science and Technology | Lam E.Y.,University of Hong Kong
IEEE Transactions on Antennas and Propagation | Year: 2012

The performance characteristics of the capacitive slot, or a slot placed between the feed and ground connections, in a planar inverted-F antenna (PIFA) are comprehensively analyzed. The PIFA capacitive slot behavior is measured inside a two antenna system within a mobile phone where the first antenna is a multiple band PIFA and the second antenna is a higher frequency band PIFA directly overlapping with the first antenna higher frequency band. The dual band PIFA in this paper is designed to be resonant in the quad-band GSM+3G/4G, and the second PIFA is resonant in the 3G/4G frequency bands. The capacitive slot has three types of behaviors: affect the matching of existing frequency resonances, induce another frequency resonance, and improve the isolation between the two antennas. Together with optimal antenna ground and feed placement, the capacitive slot can act as a notched bandstop filter to decrease the S 21 mutual coupling between the two antennas by over 20 dB and decrease the envelope correlation by almost one order of magnitude. © 1963-2012 IEEE.

Liu J.,University of Hong Kong | Zhang F.-C.,University of Hong Kong | Law K.T.,Hong Kong University of Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

Recent observation of zero bias conductance peaks in semiconductor wire/superconductor heterostructures has generated great interest, and there is a hot debate on whether the observation is associated with Majorana fermions (MFs). Here we study the local and crossed Andreev reflections of two normal leads attached to the two ends of a superconductor-semiconductor wire. We show that the MFs induced crossed Andreev reflections have significant effects on the shot noise of the device and strongly enhance the current-current correlations between the two normal leads. The measurements of shot noise and current-current correlations can be used to identify MFs. © 2013 American Physical Society.

Leung D.Y.C.,University of Hong Kong | Caramanna G.,Heriot - Watt University | Maroto-Valer M.M.,Heriot - Watt University
Renewable and Sustainable Energy Reviews | Year: 2014

Global warming and climate change concerns have triggered global efforts to reduce the concentration of atmospheric carbon dioxide (CO2). Carbon dioxide capture and storage (CCS) is considered a crucial strategy for meeting CO2 emission reduction targets. In this paper, various aspects of CCS are reviewed and discussed including the state of the art technologies for CO2 capture, separation, transport, storage, leakage, monitoring, and life cycle analysis. The selection of specific CO2 capture technology heavily depends on the type of CO2 generating plant and fuel used. Among those CO2 separation processes, absorption is the most mature and commonly adopted due to its higher efficiency and lower cost. Pipeline is considered to be the most viable solution for large volume of CO2 transport. Among those geological formations for CO2 storage, enhanced oil recovery is mature and has been practiced for many years but its economical viability for anthropogenic sources needs to be demonstrated. There are growing interests in CO2 storage in saline aquifers due to their enormous potential storage capacity and several projects are in the pipeline for demonstration of its viability. There are multiple hurdles to CCS deployment including the absence of a clear business case for CCS investment and the absence of robust economic incentives to support the additional high capital and operating costs of the whole CCS process. © 2014 Published by Elsevier Ltd.

Leung K.W.,Hong Kong University of Science and Technology | Wong A.S.,University of Hong Kong
Chinese Medicine | Year: 2010

The therapeutic potential of ginseng has been studied extensively, and ginsenosides, the active components of ginseng, are shown to be involved in modulating multiple physiological activities. This article will review the structure, systemic transformation and bioavailability of ginsenosides before illustration on how these molecules exert their functions via interactions with steroidal receptors. The multiple biological actions make ginsenosides as important resources for developing new modalities. Yet, low bioavailability of ginsenoside is one of the major hurdles needs to be overcome to advance its use in clinical settings. © 2010 Leung and Wong; licensee BioMed Central Ltd.

Yan W.M.,University of Hong Kong | Li X.S.,Hong Kong University of Science and Technology
Geotechnique | Year: 2011

This paper presents a thermodynamically consistent constitutive model for natural soils with bonds. In the model, the free energy (the internal energy available to do work) is contributed partly by the so-called frozen or locked energy, whose evolution is assumed to be homogeneously related to the irrecoverable deformation. During loading, the bonds existing in the natural soil not only boost the dissipation rate but also liberate certain historically accumulated locked energy. Such effects, however, are diminished as loading proceeds and the bonds are destroyed. The novel aspect of the present model is that it accommodates both the Mohr-Coulomb and critical-state failure modes, and the two modes are unified through the evolution law of a thermodynamic force associated with the locked bonding energy. As compared with the classical Cam-clay models, the model contains two additional material constants, where one is proposed by Collins & Kelly to improve the shape of the yield surface, and the other is dedicated to bonding evolution. The calibration procedure for the material parameters is provided. The capability of the model is demonstrated by a series of model simulations on a hypothetical bonded soil under various triaxial loading paths, and the model response is also compared with representative testing results in the literature.

Siu F.-M.,CAS Shenzhen Institutes of Advanced Technology | Siu F.-M.,University of Hong Kong | Pommier Y.,U.S. National Cancer Institute
Nucleic Acids Research | Year: 2013

Topoisomerase IB (Top1) inhibitors, such as camptothecin (CPT), stabilize the Top1-DNA cleavage complex in a DNA sequence-dependent manner. The sequence selectivity of Top1 inhibitors is important for targeting specific genomic sequences of therapeutic value. However, the molecular mechanisms underlying this selectivity remain largely unknown. We performed molecular dynamics simulations to delineate structural, dynamic and energetic features that contribute to the differential sequence selectivity of the Top1 inhibitors. We found the sequence selectivity of CPT to be highly correlated with the drug binding energies, dynamic and structural properties of the linker domain. Chemical insights, gained by perresidue binding energy analysis revealed that the non-polar interaction between CPT and nucleotide at the+1 position of the cleavage site was the major (favorable) contributor to the total binding energy. Mechanistic insights gained by a potential of mean force analysis implicated that the drug dissociation step was associated with the sequence selectivity. Pharmaceutical insights gained by our molecular dynamics analyses explained why LMP-776, an indenoisoquinoline derivative under clinical development at the National Institutes of Health, displays different sequence selectivity when compared with camptothecin and its clinical derivatives.

Fong K.F.,Hong Kong University of Science and Technology | Lee C.K.,University of Hong Kong
Applied Energy | Year: 2014

Trigeneration, which is able to provide cooling, heating and power, has been advocated to be a sustainable solution for building use in the urban area. With the high-temperature feature and maintenance convenience, solid oxide fuel cell (SOFC) becomes a promising prime mover of trigeneration. In this study, two zero grid-electricity design strategies of SOFC-trigeneration system for high-rise building were proposed and evaluated. The first zero design approach, named full-SOFC strategy, is to design the rated capacity of SOFC by matching the demand peak of electrical power without the need of grid connection. The second one, called partial-SOFC strategy, is to satisfy the peak electrical demand partly by the SOFC and partly by the grid, but still maintaining net zero grid-electricity in a year time. In view of the system complexity and the component interaction of SOFC-trigeneration, the environmental and energy performances of different cases were evaluated through year-round dynamic simulation. Compared to the conventional provisions of cooling, heating and power for building, the full- and the partial-SOFC-trigeneration systems could have 51.4% and 23.9% carbon emission cut per annum respectively. In terms of year-round electricity demand, the two zero grid-electricity strategies had corresponding savings of 7.1% and 2.8%. As a whole, the full-SOFC-trigeneration assures both environmental and energy merits for high-rise building in the hot and humid climate. © 2013 Elsevier Ltd.

Matinlinna J.P.,University of Hong Kong | Lassila L.V.,University of Turku
Dental Materials | Year: 2011

Objective: To evaluate the effect of five experimental silane monomer primers in vitro on the shear bond strength of a phosphate ester resin-composite cement bonded to a silicatized zirconia framework. Methods: A total of 144 planar zirconia (Procera AllZircon) specimens were subjected to tribochemical silica treatment, randomly divided into 12 sub-groups (n = 12), and silanized with 1.0% (v/v) activated solutions of 3-acryloxypropyltrimethoxysilane, 3 glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, styrylethyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane, which had been prepared in 95% ethanol (pH 4.5). A ready-to-use 3- methacryloxypropyltrimethoxysilane (RelyX™ Ceramic Primer) was used as the control. One resincomposite cement (RelyX™ Unicem) stub was bonded to each silicatized and silanized zirconia specimen. Half of the specimen groups were dry-tested and half were thermo-cycled at 6000 cycles between 5 °C and 55 °C, with a constant dwelling time of 30 s. The shear bond strengths of the cement stubs bonded to zirconia were measured using a universal testing machine using a constant cross-head speed of 1 mm/min. The silane primer activation was evaluated using Fourier-transform infrared spectroscopy. Results: The highest shear bond strength was obtained for 3- acryloxypropyltrimethoxysilane in dry storage, 11.7 MPa (SD, 2.3 MPa) and after thermo-cycling 17.6 (4.1) MPa for glycidoxypropyltrimethoxysilane. The lowest shear bond strength values were obtained with control silane: in dry storage, 4.5 (1.3) MPa, after thermo-cycling 6.5 (2.6) MPa. Thermo-cycling increased the bond strengths significantly (ANOVA, p < 0.001) and differently for each type of silane (ANOVA, p < 0.001). Significance: Silanization with five experimental silane primers in vitro produced significantly greater shear bond strengths than the ready-to-use control silane. © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Harko T.,University of Hong Kong | Lobo F.S.N.,University of Lisbon
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We investigate the possibility that dark matter is a mixture of two noninteracting perfect fluids, with different four-velocities and thermodynamic parameters. The two-fluid model can be described as an effective single anisotropic fluid, with distinct radial and tangential pressures. The basic equations describing the equilibrium structure of the two-fluid dark matter model, and of the tangential velocity of test particles in stable circular orbits, are obtained for the case of a spherically symmetric static geometry. By assuming a nonrelativistic kinetic model for the dark matter particles, the density profile and the tangential velocity of the dark matter mixture are obtained by numerically integrating the gravitational field equations. The cosmological implications of the model are also briefly considered, and it is shown that the anisotropic two-fluid model isotropizes in the large-time limit. © 2011 American Physical Society.

Harko T.,University of Hong Kong | Lobo F.S.N.,University of Lisbon
European Physical Journal C | Year: 2010

We generalize the f(R) type gravity models by assuming that the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar R and of the matter Lagrangian Lm. We obtain the gravitational field equations in the metric formalism, as well as the equations of motion for test particles, which follow from the covariant divergence of the energy-momentum tensor. The equations of motion for test particles can also be derived from a variational principle in the particular case in which the Lagrangian density of the matter is an arbitrary function of the energy density of the matter only. Generally, the motion is non-geodesic, and it takes place in the presence of an extra force orthogonal to the four-velocity. The Newtonian limit of the equation of motion is also considered, and a procedure for obtaining the energy-momentum tensor of the matter is presented. The gravitational field equations and the equations of motion for a particular model in which the action of the gravitational field has an exponential dependence on the standard general relativistic Hilbert-Einstein Lagrange density are also derived. © 2010 Springer-Verlag / Società Italiana di Fisica.

Chen W.,Nanjing Southeast University | Ron Hui S.Y.,University of Hong Kong | Ron Hui S.Y.,Imperial College London
IEEE Transactions on Power Electronics | Year: 2012

While LEDs enjoy relatively long lifetime up to 10 years, the lifetime of traditional LED drivers using electrolytic capacitor as storage element is limited to typically less than 5 years. In this paper, an ac/dc LED driver without electrolytic capacitor is studied. Compared with other methods to eliminate electrolytic capacitor, the proposed driver has the advantages of almost unity input power factor and constant output current for LEDs. The operation principle, detailed design procedure of the main circuit, and control strategy are presented. The feasibility of the proposed converter has been successfully verified by experiments. © 2011 IEEE.

Davies M.R.,Wellcome Trust Sanger Institute | Davies M.R.,University of Queensland | Davies M.R.,Queen Mary Hospital | Davies M.R.,University of Hong Kong | Davies M.R.,China 3 State Key Laboratory For Emerging Infectious Diseases
Nature genetics | Year: 2015

A scarlet fever outbreak began in mainland China and Hong Kong in 2011 (refs. 1-6). Macrolide- and tetracycline-resistant Streptococcus pyogenes emm12 isolates represent the majority of clinical cases. Recently, we identified two mobile genetic elements that were closely associated with emm12 outbreak isolates: the integrative and conjugative element ICE-emm12, encoding genes for tetracycline and macrolide resistance, and prophage ΦHKU.vir, encoding the superantigens SSA and SpeC, as well as the DNase Spd1 (ref. 4). Here we sequenced the genomes of 141 emm12 isolates, including 132 isolated in Hong Kong between 2005 and 2011. We found that the introduction of several ICE-emm12 variants, ΦHKU.vir and a new prophage, ΦHKU.ssa, occurred in three distinct emm12 lineages late in the twentieth century. Acquisition of ssa and transposable elements encoding multidrug resistance genes triggered the expansion of scarlet fever-associated emm12 lineages in Hong Kong. The occurrence of multidrug-resistant ssa-harboring scarlet fever strains should prompt heightened surveillance within China and abroad for the dissemination of these mobile genetic elements.

Bohmer C.G.,University College London | Harko T.,University of Hong Kong | Lobo F.S.N.,University of Lisbon
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

In this work, we explore the possibility that static and spherically symmetric traversable wormhole geometries are supported by modified teleparallel gravity or f(T) gravity, where T is the torsion scalar. Considering the field equations with an off-diagonal tetrad, a plethora of asymptotically flat exact solutions are found, which satisfy the weak and the null energy conditions at the throat and its vicinity. More specifically, considering T=0, we find the general conditions for a wormhole satisfying the energy conditions at the throat and present specific examples that satisfy the energy conditions throughout the spacetime. As a consistency check, we also verify that in the teleparallel equivalent of general relativity, i.e., f(T)=T, one regains the standard general relativistic field equations for wormhole physics. Furthermore, considering specific choices for the f(T) form and for the redshift and shape functions, several solutions of wormhole geometries are found that satisfy the energy conditions at the throat and its neighborhood. As in their general relativistic counterparts, these f(T) wormhole geometries present far-reaching physical and cosmological implications, such as being theoretically useful as shortcuts in spacetime and for inducing closed timelike curves, possibly violating causality. © 2012 American Physical Society.

Harko T.,University of Hong Kong | Lobo F.S.N.,University of Lisbon
Astroparticle Physics | Year: 2012

A two-fluid dark matter model, in which dark matter is represented as a two-component fluid thermodynamic system, without interaction between the constituent particles of different species, and with each distinct component having a different four-velocity, was recently proposed in Harko and Lobo [T. Harko, F.S.N. Lobo, Phys. Rev. D 83 (2011) 124051]. In the present paper we further investigate the two-fluid dark matter model, by assuming that the two dark matter components are pressureless, non-comoving fluids. For this particular choice of equations of state the dark matter distribution can be described as a single anisotropic fluid, with vanishing tangential pressure, and non-zero radial pressure. We investigate the properties of this model in the region of constant velocity galactic rotation curves, where the dynamics of the test particles is essentially determined by the dark matter only. By solving the general relativistic equations of mass continuity and hydrostatic equilibrium we obtain the geometric and physical parameters of the dark matter halos in the constant velocity region in an exact analytical form. The general, radial coordinate dependent, functional relationship between the energy density and the radial pressure is also determined, and it differs from a simple barotropic equation of state. © 2012 Elsevier B.V. All rights reserved.

Chan S.N.,University of Hong Kong | Thoe W.,University of Hong Kong | Lee J.H.W.,Hong Kong University of Science and Technology
Water Research | Year: 2013

Bacterial level (e.g. Escherichia coli) is generally adopted as the key indicator of beach water quality due to its high correlation with swimming associated illnesses. A 3D deterministic hydrodynamic model is developed to provide daily water quality forecasting for eight marine beaches in Tsuen Wan, which are only about 8 km from the Harbour Area Treatment Scheme (HATS) outfall discharging 1.4 million m3/d of partially-treated sewage. The fate and transport of the HATS effluent and its impact on the E. coli level at nearby beaches are studied. The model features the seamless coupling of near field jet mixing and the far field transport and dispersion of wastewater discharge from submarine outfalls, and a spatial-temporal dependent E. coli decay rate formulation specifically developed for sub-tropical Hong Kong waters. The model prediction of beach water quality has been extensively validated against field data both before and after disinfection of the HATS effluent. Compared with daily beach E. coli data during August-November 2011, the model achieves an overall accuracy of 81-91% in forecasting compliance/exceedance of beach water quality standard. The 3D deterministic model has been most valuable in the interpretation of the complex variation of beach water quality which depends on tidal level, solar radiation and other hydro-meteorological factors. The model can also be used in optimization of disinfection dosage and in emergency response situations. © 2012 Elsevier Ltd.

News Article | February 17, 2017
Site: news.yahoo.com

BEIJING (Reuters) - Bird flu infection rates on Chinese poultry farms may be far higher than previously thought, because the strain of the deadly virus that has killed more than 100 people this winter is hard to detect in chickens and geese, animal health experts say. Poultry that have contracted the H7N9 strain of the avian flu virus show little or no sign of symptoms. That means any infection is only likely to be detected if farmers or health authorities carry out random tests on a flock, the experts said. But in humans, it can be deadly. That's different to other strains, such as the highly pathogenic H5N6 that struck South Korean farms in December, prompting the government to call in the army to help cull some 26 million birds. But that strain didn't kill any people. There have been multiple outbreaks of bird flu around the world in recent months, with at least half a dozen different strains circulating. The scale of the outbreaks and range of viral strains increases the chances of viruses mixing and mutating, with new versions that can spread more easily between people, experts say. For now, H7N9 is thought to be relatively difficult to spread between people. China's Center for Disease Control and Prevention has said the vast majority of people infected by H7N9 reported exposure to poultry, especially at live markets. "There are very few, if any, clinical signs when this (H7N9) virus infects birds, and that's the main reason we're not seeing reporting coming from poultry farms in China," said Matthew Stone, deputy director general for International Standards and Science at the World Organisation for Animal Health (OIE). As many as 79 people died from H7N9 bird flu in China in January alone, up to four times higher than the same month in past years. While spikes in contamination rates are normal in January - the main influenza season - the high level of human infections has prompted fears the spread of the virus among people could be the highest on record - especially as the number of bird flu cases reported by farmers has been conspicuously low. The high number of human infections points to a significant outbreak in the poultry population that is not being detected, says Guan Yi, director of the State Key Laboratory of Emerging Infectious Diseases and the Center of Influenza Research at the University of Hong Kong. "If we have so many human infections, naturally it reflects activity, an intensive outbreak in chickens. They are highly associated," he said. China has the world's largest flock of chickens, ducks and geese, and slaughtered more than 11 billion birds for meat in 2014, according to the United Nations' Food and Agriculture Organisation (FAO). The last major bird flu outbreak in China, in 2013, killed 36 people and cost the farming industry around $6.5 billion. The experts' assessment underscores the challenge for China's government and health ministry in monitoring and controlling the H7N9 outbreak in both people and poultry. While, with few visible signs of infection in birds, it's easier for farmers to flout the reporting rules and continue selling poultry at market, Stone at the OIE said China has a "very significant" surveillance program at live markets. The government promised on Thursday to tighten controls on markets and poultry transport to help battle the virus. The agriculture ministry last month collected more than 102,000 serum samples and 55,000 virological samples from birds in 26 provinces. Of the latter samples, only 26 tested positive for the virus, according to data on the ministry's website. But the rapid rise in human infections and spread to a wider geographic area is likely to increase pressure on Beijing to do more poultry testing at markets and on farms. The ministry did not respond to faxed questions on its surveillance efforts. The National Health and Family Planning Commission said on Thursday the spread of H7N9 among people was slowing. Some Chinese netizens have called for more timely reports on infections, and some experts have said China has been slow to respond to the human outbreak. The authorities have warned the public to stay alert for the virus, cautioning against panic. Others played down the threat to humans, as long as they stay away from live markets.

News Article | February 15, 2017
Site: spaceref.com

Like cosmic lighthouses sweeping the universe with bursts of energy, pulsars have fascinated and baffled astronomers since they were first discovered 50 years ago. In two studies, international teams of astronomers suggest that recent images from NASA's Chandra X-ray Observatory of two pulsars -- Geminga and B0355+54 -- may help shine a light on the distinctive emission signatures of pulsars, as well as their often perplexing geometry. Pulsars are a type of neutron star that are born in supernova explosions when massive stars collapse. Discovered initially by lighthouse-like beams of radio emission, more recent research has found that energetic pulsars also produce beams of high energy gamma rays. Interestingly, the beams rarely match up, said Bettina Posselt, senior research associate in astronomy and astrophysics, Penn State. The shapes of observed radio and gamma-ray pulses are often quite different and some of the objects show only one type of pulse or the other. These differences have generated debate about the pulsar model. "It's not fully understood why there are variations between different pulsars," said Posselt. "One of the main ideas here is that pulse differences have a lot to do with geometry -- and it also depends on how the pulsar's spin and magnetic axes are oriented with respect to line of sight whether you see certain pulsars or not, as well as how you see them." Chandra's images are giving the astronomers a closer than ever look at the distinctive geometry of the charged particle winds radiating in X-ray and other wavelengths from the objects, according to Posselt. Pulsars rhythmically rotate as they rocket through space at speeds reaching hundreds of kilometers a second. Pulsar wind nebulae (PWN) are produced when the energetic particles streaming from pulsars shoot along the stars' magnetic fields, form tori -- donut-shaped rings -- around the pulsar's equatorial plane, and jet along the spin axis, often sweeping back into long tails as the pulsars' quickly cut through the interstellar medium. "This is one of the nicest results of our larger study of pulsar wind nebulae," said Roger W. Romani, professor of physics at Stanford University and principal investigator of the Chandra PWN project. "By making the 3-D structure of these winds visible, we have shown how one can trace back to the plasma injected by the pulsar at the center. Chandra's fantastic X-ray acuity was essential for this study, so we are happy that it was possible to get the deep exposures that made these faint structures visible." A spectacular PWN is seen around the Geminga pulsar. Geminga -- one of the closest pulsars at only 800 light-years away from Earth -- has three unusual tails, said Posselt. The streams of particles spewing out of the alleged poles of Geminga -- or lateral tails -- stretch out for more than half a light-year, longer than 1,000 times the distance between the Sun and Pluto. Another shorter tail also emanates from the pulsar. The astronomers said that a much different PWN picture is seen in the X-ray image of another pulsar called B0355+54, which is about 3,300 light-years away from Earth. The tail of this pulsar has a cap of emission, followed by a narrow double tail that extends almost five light-years away from the star. While Geminga shows pulses in the gamma ray spectrum, but is radio quiet, B0355+54 is one of the brightest radio pulsars, but fails to show gamma rays. "The tails seem to tell us why that is," said Posselt, adding that the pulsars' spin axis and magnetic axis orientations influence what emissions are seen on Earth. According to Posselt, Geminga may have magnetic poles quite close to the top and bottom of the object, and nearly aligned spin poles, much like Earth. One of the magnetic poles of B0355+54 could directly face the Earth. Because the radio emission occurs near the site of the magnetic poles, the radio waves may point along the direction of the jets, she said. Gamma-ray emission, on the other hand, is produced at higher altitudes in a larger region, allowing the respective pulses to sweep larger areas of the sky. "For Geminga, we view the bright gamma ray pulses and the edge of the pulsar wind nebula torus, but the radio beams near the jets point off to the sides and remain unseen," Posselt said. The strongly bent lateral tails offer the astronomers clues to the geometry of the pulsar, which could be compared to either jet contrails soaring into space, or to a bow shock similar to the shockwave created by a bullet as it is shot through the air. Oleg Kargaltsev, assistant professor of physics, George Washington University, who worked on the study on B0355+54, said that the orientation of B0355+54 plays a role in how astronomers see the pulsar, as well. The study is available online in arXiv. "For B0355+54, a jet points nearly at us so we detect the bright radio pulses while most of the gamma-ray emission is directed in the plane of the sky and misses the Earth," said Kargaltsev. "This implies that the pulsar's spin axis direction is close to our line-of-sight direction and that the pulsar is moving nearly perpendicularly to its spin axis." Noel Klingler, a graduate research assistant in physics, George Washington University, and lead author of the B0355+54 paper, added that the angles between the three vectors -- the spin axis, the line-of-sight, and the velocity -- are different for different pulsars, thus affecting the appearances of their nebulae. "In particular, it may be tricky to detect a PWN from a pulsar moving close to the line-of-sight and having a small angle between the spin axis and our line-of-sight," said Klingler. In the bow-shock interpretation of the Geminga X-ray data, Geminga's two long tails and their unusual spectrum may suggest that the particles are accelerated to nearly the speed of light through a process called Fermi acceleration. The Fermi acceleration takes place at the intersection of a pulsar wind and the interstellar material, according to the researchers, who report their findings on Geminga online and in the current issue of Astrophysical Journal. Although different interpretations remain on the table for Geminga's geometry, Posselt said that Chandra's images of the pulsar are helping astrophysicists use pulsars as particle physics laboratories. Studying the objects gives astrophysicists a chance to investigate particle physics in conditions that would be impossible to replicate in a particle accelerator on earth. "In both scenarios, Geminga provides exciting new constraints on the acceleration physics in pulsar wind nebulae and their interaction with the surrounding interstellar matter," she said. * "Deep Chandra Observations of the Pulsar Wind Nebula Created by PSR B0355+54," Noel Klingler et al., 2016 Dec. 20, Astrophysical Journal [http://iopscience.iop.org/article/10.3847/1538-4357/833/2/253, preprint: https://arxiv.org/abs/1610.06167]. * "Geminga's Puzzling Pulsar Wind Nebula," B. Posselt et al., 2017, to appear in Astrophysical Journal [http://apj.aas.org, preprint: https://arxiv.org/abs/1611.03496]. Other team members include George C. Pavlov, senior scientist in astronomy and astrophysics, Penn State; Pat O. Slane, lecturer and senior astrophysicist, Harvard Smithsonian Center for Astrophysics; Roger Romani, professor of physics, Stanford University; Niccolo Bucciantini, permanent researcher, INAF Osservatorio Astorfisico di Arcetri; Andrei M. Bykov, head of the Laboratory for High Energy Astrophysics, Ioffe Physical-Technical Institute; Martin C. Weisskopf, project scientist, NASA/Marshall Space Flight Center; Stephen Chi-Yung Ng, assistant professor of physics, University of Hong Kong. Additional team members for the study on B0355+54 include Blagoy Rangelov, postdoctoral researcher, George Washington University; Tea Temim, JWST Support Scientist, Space Telescope Science Institute; Douglas A. Swartz, research scientist, Marshall Space Flight Center and Rolf Buehler, staff scientist, DESY Zeuthen. NASA and the Russian Science Foundation supported this work. Please follow SpaceRef on Twitter and Like us on Facebook.

News Article | December 28, 2016
Site: www.scientificamerican.com

The first humans venturing onto the Tibetan Plateau, often called the “roof of the world,” faced one of the most brutal environments our species can endure. At an average elevation of over 4,500 meters, it is a cold and arid place with half the oxygen present at sea level. Science has long held that humans did not set foot in this alien place until 15,000 years ago, as suggested by archaeological evidence of the earliest known settlement on the northeastern fringe of the plateau 3,000 meters above sea level. But now new genetic data indicate this may have occurred much earlier—possibly as far back as the last ice age, 62,000 years ago. A better understanding of modern Tibetans’ genetic mix and diversity could help reconstruct the history of migration and population expansion in the region, and may help unravel the mystery of the ethnic origins of Tibetans—and of how humans have adapted to low-oxygen conditions at high altitudes. For the new study, researchers sequenced the entire genomes of 38 ethnic Tibetans and 39 Han Chinese (the country’s majority ethnic group), and compared the results with published genomic sequences of other ethnic groups around the world—information that allowed the team to pinpoint the common genetic origin of different populations and to get a better grasp on the history of migration in Tibet. “Tibetan-specific DNA sequences can be traced back to ancestors 62,000-38,000 years ago…This represents the earliest colonization of the Tibetan Plateau,” says Shuhua Xu, a population geneticist at the Chinese Institute of Sciences’ Shanghai Institutes for Biological Sciences. Xu’s work was published in September in the American Journal of Human Genetics, and presented at the American Society of Human Genetics’ annual meeting in Vancouver. Since that initial migration, as the ice age tightened its grip on the plateau, genetic mixing between Tibetans and non-Tibetans probably ground to a halt for tens of thousands of years—suggesting that movement into Tibet dropped to the minimum. “The migration routes were probably cut off by ice sheets,” Xu says. “It’s simply too harsh even for the toughest hunter-gatherers.” But about 15,000 to 9,000 years ago—after the so-called last glacial maximum (LGM), during which the Earth’s ice cover had reached its most extensive point and climate was at its harshest—people flocked into Tibet en masse. “It’s the most significant wave of migration that shaped the modern Tibetan gene pool,” Xu says. “We can really see rapid population expansion [on the plateau] during that time.” Interestingly, he adds, this was also when the common ancestor of Tibetans and Han Chinese split—contrary to a previous study suggesting that the divergence took place as late as 2,750 years ago. “This is the first study to sequence the entire genome of Tibetans, and the resolution is really impressive,” says Mark Aldenderfer, an archaeologist at the University of California, Merced, who was not involved in Xu’s study. The much earlier divergence between Tibetans and Han Chinese makes sense because there are continuous material cultures on the plateau since 15,000 years ago, he says. The study, Aldenderfer adds, “also provides fine details of how different populations from various directions may have combined their genes to ultimately create the people that we call Tibetans.” The data show that 94 percent of the present-day Tibetan genetic makeup came from modern humans—possibly those who ventured into Tibet in the second wave of migration—and the rest came from archaic hominins such as Denisovans, Neandertals and unknown groups. The modern part of the Tibetan genome shares 82 percent similarity with East Asians, 11 percent with Central Asians, and 6 percent with South Asians. “Among all ethic groups, Han Chinese are most closely related to Tibetans,” Xu says. The findings also reveal a startling genetic continuity since the plateau was first colonized 62,000 years ago. “This suggests that Tibet has always been populated—even during the toughest times as far as climate was concerned,” Xu says. That idea contradicts the commonly held notion that any early plateau dwellers would have been eliminated during harsh climate intervals such as LGM and another period known as the Younger Dryas between 12,900 and 11,600 years ago, says David Zhang, a geographer at the University of Hong Kong, who was not involved in Xu’s research. In 2002 Zhang and a colleague published a controversial study in Geophysical Review Letters showing marks of hands and feet from at least six individuals in rocks that were once soft mud, which was dated to 20,000 years ago at 4,000 meters above sea level in the heart of Tibet. Based on this they theorized that people were living in Tibet at the height of LGM, but the lack of archaeological finds near the site has cast doubt on this. “Many people don’t think it’s possible,” Aldenderfer says. “But there were plenty of places for [those early populations] to live where local conditions weren’t that bad, such as the big river valleys on the plateau.” The handprints and footprints were uncovered near one of the plateau’s many hot springs, which could have served as refuges for plants, animals and humans, he adds. Two independent archaeological studies presented at the 33rd International Geographical Congress, held in August in Beijing, also support the antiquity of Tibet settlement as suggested by Xu’s genetic data. A team led by archaeologist Guanghui Dong of Lanzhou University in Gansu province unveiled the earliest archaeological evidence of human presence—dating to 39,000-31,000 years ago—on the southeastern fringe of the Tibetan Plateau. The site, rich with stone tools and animal bones, lies at 2,500 meters above sea level at the bank of the Salween River. “This may represent one of the first steps of human colonization on the plateau,” Dong says. “Those hunter-gathers might then expand to the inner plateau along the river valley.” The second study pushes back the dates of human settlement above 4,000 meters by 4,000 years. Qinghai Normal University archaeologist Guangliang Hou and some of his colleagues recently excavated an archaeological site dated to 11,500 years ago, which is in line with the second and more important wave of migration that Xu’s study suggests. Hou said at the geographical congress that the site, close to a main tributary of the Yellow River, is teeming with charcoal—a telltale sign of fire use by humans. “This may have helped the plateau dwellers to survive the harsh conditions at such high elevations nearing the end of the Younger Dryas,” he says. “It’s increasingly clear that there has been much earlier and much more persistent human occupation of the plateau than we previously thought,” Aldenderfer says. He stresses, however, that pieces are still missing from the puzzle: “More excavations are required to close those gaps.”

Zhu G.-R.,Wuhan University of Technology | Tan S.-C.,University of Hong Kong | Chen Y.,Huazhong University of Science and Technology | Tse C.K.,Hong Kong Polytechnic University
IEEE Transactions on Power Electronics | Year: 2013

Fuel-cell power systems comprising single-phase dc/ac inverters draw low-frequency ac ripple currents at twice the output frequency from the fuel cell. Such a 100/120Hz ripple current may create instability in the fuel-cell system, lower its efficiency, and shorten the lifetime of a fuel cell stack. This paper presents a waveform control method that can mitigate such a low-frequency ripple current being drawn from the fuel cell while the fuel-cell system delivers ac power to the load through a differential inverter. This is possible because with the proposed solution, the pulsation component (cause of ac ripple current) of the output ac power will be supplied mainly by the two output capacitors of the differential inverter while the average dc output power is supplied by the fuel cell. Theoretical analysis, simulation, and experimental results are provided to explain the operation and showcase the performance of the approach. Results validate that the proposed solution can achieve significant mitigation of the current ripple as well as high-quality output voltage without extra hardware. Application of the solution is targeted at systems where current ripple mitigation is required, such as for the purpose of eliminating electrolytic capacitor in photovoltaic and LED systems. © 1986-2012 IEEE.

Yu Z.,Tsinghua University | Thywissen J.H.,University of Toronto | Zhang S.,University of Hong Kong
Physical Review Letters | Year: 2015

We investigate the properties of a spinless Fermi gas close to a p-wave interaction resonance. We show that the effects of interaction near a p-wave resonance are captured by two contacts, which are related to the variation of energy with the p-wave scattering volume v and with the effective range R in two adiabatic theorems. Exact pressure and virial relations are derived. We show how the two contacts determine the leading and subleading asymptotic behavior of the momentum distribution (∼1/k2 and ∼1/k4) and how they can be measured experimentally by radio-frequency and photoassociation spectroscopies. Finally, we evaluate the two contacts at high temperature with a virial expansion. © 2015 American Physical Society.

Freeman G.,University of Hong Kong | Cowling B.J.,University of Hong Kong | Mary Schooling C.,University of Hong Kong | Mary Schooling C.,CUNY - Hunter College
International Journal of Epidemiology | Year: 2013

Mendelian randomization, which is instrumental variable analysis using genetic variants as instruments, is an increasingly popular method of making causal inferences from observational studies. In order to design efficient Mendelian randomization studies, it is essential to calculate the sample sizes required. We present formulas for calculating the power of a Mendelian randomization study using one genetic instrument to detect an effect of a given size, and the minimum sample size required to detect effects for given levels of significance and power, using asymptotic statistical theory. We apply the formulas to some example data and compare the results with those from simulation methods. Power and sample size calculations using these formulas should be more straightforward to carry out than simulation approaches. These formulas make explicit that the sample size needed for Mendelian randomization study is inversely proportional to the square of the correlation between the genetic instrument and the exposure and proportional to the residual variance of the outcome after removing the effect of the exposure, as well as inversely proportional to the square of the effect size. © The Author 2013; All rights reserved.

Sims L.D.,Asia Pacific Veterinary Information Services | Peiris M.,University of Hong Kong
Current Topics in Microbiology and Immunology | Year: 2013

The occurrence of avian influenza A(H5N1) in Hong Kong in 1997 led to the development of a "One-Health" approach to deal with emerging infectious diseases that has been applied to other emergent diseases such as SARS and the pandemic H1N1 2009. Evaluation of poultry marketing and production systems and investigations at the animal-human interface, led to defining the routes of human exposure to avian influenza and factors that allowed virus to multiply and persist. Active and systematic surveillance of apparently healthy as well as diseased poultry and wild birds provided evidence of ongoing virus evolution in the wider region. Epidemiological studies, supplemented with molecular epidemiology, helped to elucidate the role of the poultry marketing system and live poultry markets in the persistence of avian influenza viruses and provided evidence for the impact of interventions designed to interrupt virus transmission. Enhanced bio-security, active surveillance together with targeted and evidence-based interventions in the poultry production, and marketing system together with poultry vaccination has prevented further human H5N1 disease and minimized outbreaks of poultry disease in Hong Kong. Similar strategies have led to the understanding of the emergence of SARS and provided options for preventing the re-emergence of this disease. Surveillance of influenza in swine has provided insights into the emergence of the 2009 pandemic, to the reverse zoonosis of the pandemic virus from humans to swine and to the emergence of novel reassortant viruses within swine. "One Health" strategies are not "cost-free" and require sensitive implementation to optimize food-safety and food security, while safeguarding the economics of animal husbandry and the environment and remaining sensitive to cultural practices. © Springer-Verlag Berlin Heidelberg 2013.

Fu Z.,Shanxi University | Huang L.,Shanxi University | Meng Z.,Shanxi University | Wang P.,Shanxi University | And 5 more authors.
Nature Physics | Year: 2014

The search for topological superconductors is a challenging task. One of the most promising directions is to use spin-orbit coupling through which an s-wave superconductor can induce unconventional p-wave pairing in a spin-polarized metal. Recently, synthetic spin-orbit couplings have been realized in cold-atom systems where instead of a proximity effect, s-wave pairing originates from a resonant coupling between s-wave molecules and itinerant atoms. Here we demonstrate a dynamic process in which spin-orbit coupling coherently produces s-wave Feshbach molecules from a fully polarized Fermi gas, and induces a coherent oscillation between these two. This demonstrates experimentally that spin-orbit coupling does coherently couple singlet and triplet states, and implies that the bound pairs of this system have a triplet p-wave component, which can become a topological superfluid by further cooling to condensation and confinement to one dimension. © 2014 Macmillan Publishers Limited.

Yip P.S.F.,University of Hong Kong | Caine E.D.,University of Rochester
Journal of Epidemiology and Community Health | Year: 2011

Background: Existing studies have described a strong correlation between unemployment rates and suicide rates, but the exact mechanisms through which they may interact with one another remain unknown. Method This study examined the complex relationships between suicide rates and both regional unemployment rates and individual employment status during times of economic recession (2000-3) and recovery (2003-6) in Hong Kong. Results: Despite the strong correlation (0.86) between the unemployment rates and suicide rates for 2000-6, the rates of suicides within the employed and unemployed groups moved in the opposite direction from the overall population trend. That is, the suicide rate among the unemployed decreased during economic recession and increased during recovery. Conclusion: It is important to be able to distinguish precisely between population-level concepts, such as rates, and individual-level characteristics, such as employment status, when considering the development of evidence-based suicide prevention strategies.

Yu L.,University of Hong Kong | Xi J.,Tsinghua University
Electrochimica Acta | Year: 2012

A simple and efficient method to enhance the activity of Pt/C catalysts for direct ethanol fuel cells (DEFCs) by ultrasonically mixing commercial Pt/C catalyst and TiO 2 nanoparticles is reported. In this novel composite anode catalyst, the as-prepared TiO 2 nanoparticles are dispersed homogeneously in the interspaces of Pt based C nanoparticles, resulting in a great deal of TiO 2-Pt-C interfaces, which greatly accelerate the ethanol electro-oxidation reaction. Cyclic voltammetry (CV), CO stripping, chronoamperometry and electrochemical impedance spectroscopy (EIS) measurements confirm that this composite catalyst structure has excellent activity and stability toward ethanol and CO electro-oxidation compared to the pure Pt/C catalyst. Particle size and content of TiO 2 are also discussed with respect to effect on catalyst performance. © 2012 Elsevier Ltd. All rights reserved.

Lau R.Y.K.,University of Hong Kong | Xia Y.,Tsinghua University | Ye Y.,Harbin Institute of Technology
IEEE Computational Intelligence Magazine | Year: 2014

Abstract-There has been a rapid growth in the number of cybercr imes that cause tremendous financial loss to organizations. Recent studies reveal that cybercriminals tend to collaborate or even transact cyber-attack tools via the dark markets established in online social media. Accordingly, it presents unprecedented opportunities for researchers to tap into these underground cybercriminal communities to develop better insights about collaborative cybercrime activities so as to combat the ever increasing number of cybercrimes. The main contribution of this paper is the development of a novel weakly supervised cybercriminal network mining method to facilitate cybercrime forensics. In particular, the proposed method is underpinned by a probabilistic generative model enhanced by a novel context-sensitive Gibbs sampling algorithm. Evaluated based on two social media corpora, our experimental results reveal that the proposed method significantly outperforms the Latent Dirichlet Allocation (LDA) based method and the Support Vector Machine (SVM) based method by 5.23% and 16.62% in terms of Area Under the ROC Curve (AUC), respectively. It also achieves comparable performance as the state-of-the-art Partially Labeled Dirichlet Allocation (PLDA) method. To the best of our knowledge, this is the first successful research of applying a probabilistic generative model to mine cybercriminal networks from online social media. © 2014 IEEE.

Gan R.-Y.,University of Hong Kong | Li H.-B.,Sun Yat Sen University
International Journal of Molecular Sciences | Year: 2014

Liver kinase B1 (LKB1), known as a serine/threonine kinase, has been identified as a critical cancer suppressor in many cancer cells. It is a master upstream kinase of 13 AMP-activated protein kinase (AMPK)-related protein kinases, and possesses versatile biological functions. LKB1 gene is mutated in many cancers, and its protein can form different protein complexes with different cellular localizations in various cell types. The expression of LKB1 can be regulated through epigenetic modification, transcriptional regulation and post-translational modification. LKB1 dowcnstream pathways mainly include AMPK, microtubule affinity regulating kinase (MARK), salt-inducible kinase (SIK), sucrose non-fermenting protein-related kinase (SNRK) and brain selective kinase (BRSK) signalings, etc. This review, therefore, mainly discusses recent studies about the expression, regulation, downstream signaling and cancer suppressive function of LKB1, which can be helpful for better understanding of this molecular and its significance in cancers. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

Ma X.,Tsinghua University | Fung C.-H.F.,University of Hong Kong | Razavi M.,University of Leeds
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

Measurement-device-independent quantum key distribution with a finite number of decoy states is analyzed under finite-data-size assumption. By accounting for statistical fluctuations in parameter estimation, we investigate vacuum+weak- and vacuum+two-weak-decoy-state protocols. In each case, we find proper operation regimes, where the performance of our system is comparable to the asymptotic case for which the key size and the number of decoy states approach infinity. Our results show that practical implementations of this scheme can be both secure and efficient. © 2012 American Physical Society.

Duan B.,Cornell University | Wang M.,University of Hong Kong
MRS Bulletin | Year: 2011

Rapid prototyping (RP) technologies, which are based on computer-aided design and computer-aided manufacturing, are widely employed in traditional industries. They are capable of achieving extensive and detailed control over the architecture of objects to be formed and therefore are increasingly used in the biomedical engineering field. Selective laser sintering (SLS), a versatile RP technique, uses a laser beam to selectively sinter powdered materials to form three-dimensional objects according to designs that can be based on data obtained from computer-based medical imaging technologies. In this article relating to biomedical applications, the principle, materials, machine modification, and parameter optimization for SLS are reviewed. Biomedical applications of SLS, especially in the fabrication of tissue engineering scaffolds and drug/biomolecule delivery vehicles, are presented and discussed. SLS exhibits great potential for many applications in biomedical engineering. Copyright © Materials Research Society 2011.

Zheng T.,University of Hong Kong | Choy W.C.H.,University of Hong Kong | Choy W.C.H.,University of California at Los Angeles
Advanced Functional Materials | Year: 2010

This paper presents a new strategy to develop efficient organic light-emitting devices (OLEDs) by doping fluorescent- and phosphorescent-type emitters individually into two different hosts separated by an interlayer to form a fluorescence-interlayer-phosphorescence (FIP) emission architecture. One blue OLED with FIP emission structure comprising p-bis(p-N,N- diphenylaminostyryl)benzene (DSA-Ph) and bis[(4,6-di-fluorophenyl)-pyridinate-N, C2']picoIinate (Flrpic) exhibiting a peak luminance efficiency of 15.8cdA-1 at 1.54 mA cm-2 and a power efficiency of 10.2 lm W-1 at 0.1 mA cm-2 is successfully demonstrated. The results are higher than those of typical phosphorescent OLEDs with a single emission layer by 34% and 28%, respectively. From experimental and theoretical investigations on device performance, and the functions of the used emitters and interlayer, such enhancement should ascribe to the appropriate utilization of the two types of emitters. The fluorescent emitter of DSA-Ph is used to facilitate the carrier transport, and thus accelerate the generation of excitons, while the phosphorescent emitter of Flrpic could convert the generated excitons into light efficiently. The method proposed here can be applied for developing other types of red, green, and white OLEDs. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.

Zhao G.,University of Hong Kong | Zhai M.,CAS Institute of Geology and Geophysics
Gondwana Research | Year: 2013

The North China Craton (NCC) consists of Archean to Paleoproterozoic basement overlain by Mesoproterozoic to Cenozoic cover. Minor Eoarchean to Mesoarchean basement rocks are locally present in the eastern part of the NCC, but little is known about their extent, nature and tectonic evolution due to widespread reworking by later events. The Neoarchean basement in the NCC was formed during two distinct periods: 2.8-2.7 Ga and 2.6-2.5 Ga, of which the former is considered as a major period of juvenile crustal growth in the NCC as evidenced by Nd and zircon Hf isotopic data, though the 2.8-2.7 Ga rocks are not widely exposed. The 2.6-2.5 Ga rocks make up ~ 80% of the Precambrian basement of the NCC and can be divided into high-grade gneiss complexes and low- to medium-grade granite-greenstone belts that are widespread over the whole NCC, seeming to support a notion that the cratonization of the NCC occurred at ~ 2.5 Ga. However, the 2.6-2.5 Ga rocks in the eastern and western parts of the NCC (Eastern and Western Blocks) are different from those similar-aged rocks in the central part (Trans-North China Orogen), with the former dominated by gneiss domes and metamorphosed at ~ 2.5 Ga, characterized by anticlockwise P-T paths involving isobaric cooling, reflecting an origin related to the underplating of mantle-derived magmas, whereas the latter, which are defined by strike-slip ductile shear zones, large-scale thrusting and folding, and transcurrent tectonics locally with sheath folds, were metamorphosed at ~ 1.85 Ga, characterized by clockwise P-T paths involving isothermal decompression, consistent with subduction and continent-continent collision settings. In addition, komatiites/komatiitic rocks are present in the granite-greenstone belts in the eastern and western parts of the NCC, but generally are absent in the central part. These differences imply that the 2.6-2.5 Ga basement rocks in the eastern and western parts of the NCC formed under different tectonic settings from those in the central part. Although both magmatic arc and mantle plume models can be used to explain the tectonic setting of the 2.6-2.5 Ga basement rocks in the eastern part of the NCC, a mantle plume model is favored as it can reasonably interpret: (1) the exceptionally large exposure of granitoid intrusions that formed over a short time period (2.55-2.50 Ga), without systematic age progression across a ~ 800 km wide block; (2) generation of komatiitic magmas with eruption temperatures as high as ~ 1650 °C; (3) dominant domal structures; (4) bimodal volcanic assemblages in the greenstone sequences; (5) affinities of mafic rocks to continental tholeiitic basalts; and (6) metamorphism with anticlockwise P-T paths involving isobaric cooling. In contrast, the 2.6-2.5 Ga high-grade gneiss terranes and low-grade granite-greenstone belts in the central part of the NCC exhibit the same structural and metamorphic characteristics as those of Paleoproterozoic lithological elements that typify active continental margin arcs and continent-continent collisional belts. Paleoproterozoic lithological assemblages in the NCC are mainly restricted to three Paleoproterozoic linear tectonic belts in the western, central and eastern parts of the NCC, which were, respectively, named the "Khondalite Belt (Fengzhen Belt/Inner Mongolia Suture Zone)", "Trans-North China Orogen (Central Orogen Belt)" and "Jiao-Liao-Ji (Liaoji) Belt". The three belts display some of the following lithotectonic elements that are classical indicators of subduction and collision tectonics in plate tectonic regimes: (1) arc-related juvenile crust; (2) linear structural belts defined by strike-slip ductile shear zones, large-scale thrusting and folding, and sheath folds and mineral lineations; (3) high-pressure (HP) mafic and pelitic granulites, retrograde eclogites and ultrahigh temperature (UHT) rocks; (4) clockwise metamorphic P-T paths involving near-isothermal decompression; (5) possible ancient oceanic fragments and mélange; and (6) back-arc or foreland basins. These lithotectonic elements indicate that subduction- and collision-related orogenic processes must have been involved in the development of the three Paleoproterozoic belts in the NCC. Different models have been proposed for the formation and evolution of these three Paleoproterozoic orogenic belts, and one of the models suggests that the Khondalite Belt was a continent-continent collisional belt along which the Yinshan and Ordos Blocks amalgamated to form the Western Block at ~ 1.95 Ga, which then collided with the exotic Eastern Block along the Trans-North China Orogen at ~ 1.85 Ga, whereas the Jiao-Liao-Ji Belt represents a rifting-and-collision belt within the Eastern Block which underwent rifting to form an incipient oceanic basin that was closed upon itself through subduction and collision at ~ 1.9 Ga. An alternative model proposes that all of the three Paleoproterozoic orogenic belts in the NCC were initialized from continental rifting on a single continent, which was cratonized through fusing Achaean microcontinental blocks at ~ 2.5 Ga, followed by the development of incipient oceanic basins which themselves were closed in the Paleoproterozoic through subduction and collision. © 2012 International Association for Gondwana Research.

Yu L.,University of Hong Kong | Xi J.,Tsinghua University
International Journal of Hydrogen Energy | Year: 2012

We developed an ultrasonic co-deposition technique to enhance the activity of Pt/C catalyst (and Pt/CNT, PtRu/C catalysts) for direct alcohol fuel cells (DAFCs) by CeO2 nanoparticles. The composite catalyst architecture is obtained by an ultrasonically mixing commercial Pt/C catalyst and CeO 2 nanoparticles. Both Pt and CeO2 are dispersed uniformly in the electrodes resulting in a great deal of CeO2-Pt-C triple junction interfaces. Unlike traditional preparation of metal oxide supported Pt catalysts, CeO2 will not cut the connection between Pt and C in this composite catalyst structure. Electrochemical measurements confirm that CeO 2 can improve almost all Pt based catalysts (Pt/C, Pt/CNT, and PtRu/C) for almost all small molecular alcohols (methanol, ethanol, ethylene glycol, and glycerol) electro-oxidation. EIS measurement shows that reaction resistance between Pt and alcohols is decreased much by adding small CeO 2 nanoparticles. Besides, these composite catalysts have high stability. It proves CeO2 a very promising co-catalyst of Pt based catalysts for DAFCs. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Qi Z.,University of Hong Kong | Yeh A.G.O.,University of Hong Kong | Li X.,Sun Yat Sen University | Lin Z.,Sun Yat Sen University
Remote Sensing of Environment | Year: 2012

This study proposes a new four-component algorithm for land use and land cover (LULC) classification using RADARSAT-2 polarimetric SAR (PolSAR) data. These four components are polarimetric decomposition, PolSAR interferometry, object-oriented image analysis, and decision tree algorithms. First, polarimetric decomposition can be used to support the classification of PolSAR data. It is aimed at extracting polarimetric parameters related to the physical scattering mechanisms of the observed objects. Second, PolSAR interferometry is used to extract polarimetric interferometric information to support LULC classification. Third, the main purposes of object-oriented image analysis are delineating image objects, as well as extracting various textural and spatial features from image objects to improve classification accuracy. Finally, a decision tree algorithm provides an efficient way to select features and implement classification. A comparison between the proposed method and the Wishart supervised classification which is based on the coherency matrix was made to test the performance of the proposed method. The overall accuracy of the proposed method was 86.64%, whereas that of the Wishart supervised classification was 69.66%. The kappa value of the proposed method was 0.84, much higher than that of the Wishart supervised classification, which exhibited a kappa value of 0.65. The results indicate that the proposed method exhibits much better performance than the Wishart supervised classification for LULC classification. Further investigation was carried out on the respective contribution of the four components to LULC classification using RADARSAT-2 PolSAR data, and it indicates that all the four components have important contribution to the classification. Polarimetric information has significant implications for identifying different vegetation types and distinguishing between vegetation and urban/built-up. The polarimetric interferometric information extracted from repeat-pass RADARSAT-2 images is important in reducing the confusion between urban/built-up and vegetation and that between barren/sparsely vegetated land and vegetation. Object-oriented image analysis is very helpful in reducing the effect of speckle in PolSAR images by implementing classification based on image objects, and the textural information extracted from image objects is helpful in distinguishing between water and lawn. The decision tree algorithm can achieve higher classification accuracy than the nearest neighbor classification implemented using Definiens Developer 7.0, and the accuracy of the decision tree algorithm is similar with that of the support vector classification which is implemented based on the features selected using genetic algorithms. Compared with the nearest neighbor and support vector classification, the decision tree algorithm is more efficient to select features and implement classification. Furthermore, the decision tree algorithm can provide clear classification rules that can be easily interpreted based on the physical meaning of the features used in the classification. This can provide physical insight for LULC classification using PolSAR data. © 2011 Elsevier Inc.

Zhou B.,Harbin Institute of Technology | Lin Z.,University of Virginia | Lam J.,University of Hong Kong
Automatica | Year: 2012

This note is concerned with the problem of semi-globally stabilizing a linear system with an input delay and a constraint on the energy of its input. Under the condition of null controllability with vanishing energy, the parametric Lyapunov equation based L2 low gain feedback is adopted to solve the problem. The proposed approach is applied to the linearized model of the relative motion in the orbit plane of a spacecraft with respect to another spacecraft in a circular orbit around the Earth to validate its effectiveness. © 2012 Elsevier Ltd. All rights reserved.

Xu L.,University of Hong Kong | Freeman G.,University of Hong Kong | Cowling B.J.,University of Hong Kong | Schooling C.M.,University of Hong Kong | Schooling C.M.,CUNY - Hunter College
BMC Medicine | Year: 2013

Background: Testosterone therapy is increasingly promoted. No randomized placebo-controlled trial has been implemented to assess the effect of testosterone therapy on cardiovascular events, although very high levels of androgens are thought to promote cardiovascular disease.Methods: A systematic review and meta-analysis was conducted of placebo-controlled randomized trials of testosterone therapy among men lasting 12+ weeks reporting cardiovascular-related events. We searched PubMed through the end of 2012 using " (" testosterone" or " androgen" ) and trial and (" random*" )" with the selection limited to studies of men in English, supplemented by a bibliographic search of the World Health Organization trial registry. Two reviewers independently searched, selected and assessed study quality with differences resolved by consensus. Two statisticians independently abstracted and analyzed data, using random or fixed effects models, as appropriate, with inverse variance weighting.Results: Of 1,882 studies identified 27 trials were eligible including 2,994, mainly older, men who experienced 180 cardiovascular-related events. Testosterone therapy increased the risk of a cardiovascular-related event (odds ratio (OR) 1.54, 95% confidence interval (CI) 1.09 to 2.18). The effect of testosterone therapy varied with source of funding (P-value for interaction 0.03), but not with baseline testosterone level (P-value for interaction 0.70). In trials not funded by the pharmaceutical industry the risk of a cardiovascular-related event on testosterone therapy was greater (OR 2.06, 95% CI 1.34 to 3.17) than in pharmaceutical industry funded trials (OR 0.89, 95% CI 0.50 to 1.60).Conclusions: The effects of testosterone on cardiovascular-related events varied with source of funding. Nevertheless, overall and particularly in trials not funded by the pharmaceutical industry, exogenous testosterone increased the risk of cardiovascular-related events, with corresponding implications for the use of testosterone therapy. © 2013 Xu et al.; licensee BioMed Central Ltd.

Bondurand N.,French Institute of Health and Medical Research | Bondurand N.,University Paris Est Creteil | Sham M.H.,University of Hong Kong
Developmental Biology | Year: 2013

The SOX10 transcription factor is a characteristic marker for migratory multipotent neural crest (NC) progenitors as well as several of their differentiated derivatives. The involvement of SOX10 in Waardenburg-Hirschsprung disease (pigmentation defects, deafness and intestinal aganglionosis) and studies of mutant animal models have contributed significantly to the understanding of its function in neural crest cells (NCC) in general and in the melanocytes and enteric nervous system (ENS) in particular. Cell-based studies have further demonstrated the important roles of this transcription factor in maintaining the NC progenitor cell number and in determining glial cell fate. Phenotypic variability observed among patients presenting with SOX10 mutations is in agreement with molecular genetics and animal model studies, which revealed that SOX10 cooperates with different partner factors; a number of genetic modifiers of SOX10 have been identified. This study reviews the expression, regulation, and function of SOX10 in normal development of the ENS and in disease conditions, as well as the genetic and molecular interactions of SOX10 with other ENS genes/factors. We also discuss future research areas. Further understanding of SOX10 function will benefit from genomic and cell biological studies that integrate the cell-intrinsic molecular mechanisms and the interactions of the enteric NCC with the niche environment. © 2013 Elsevier Inc.

News Article | November 28, 2015
Site: www.forbes.com

When I began teaching as Visiting Professor in the MBA program at the University of Hong Kong in February 2012 I had entitled the course “Asia in the New Global Order.” At the first class one of the students asked, “Order? What Order?” Good point, I noted, and the course was re-titled “Asia in the New Global Disorder.” It is the title that has been used in Hong Kong since, but also of the courses I have been teaching at NIIT University in Rajasthan, India, and the theme for my Forbes blog.

News Article | March 1, 2017
Site: www.bbc.co.uk

A dinosaur that lived 160 million years ago had drumstick-shaped legs much like living birds, according to palaeontologists. The feathered dinosaur also had bird-like arms similar to wings. Scientists used high-powered lasers to reveal invisible details of what the creature looked like. The research could give insights into the origins of flight, which is thought to have evolved more than 150 million years ago. Michael Pittman of the University of Hong Kong said the study was a landmark in our understanding of the origins of birds. "In this study, what we've done is we've used high-powered lasers to reveal unseen soft tissues preserved alongside the bones of a feathered dinosaur called Anchiornis," he said. The research team used laser-stimulated fluorescence imaging, a technique that reveals soft tissue details that are unseen under visible light. The method involves sweeping laser light across a specimen while taking long-exposure photos with a camera. Dr Stephen Brusatte of the University of Edinburgh, who was not connected with the research, said the study produced striking evidence of just how bird-like these dinosaurs were. "This study uses high-powered lasers to generate the single best look at the wings and body outline of a dinosaur ever," he told the BBC News website. "The laser images show that this non-bird dinosaur had wings that were remarkably similar to those of living birds, down to the soft tissues." Anchiornis is Greek for "almost bird". The dinosaur lived in China during the late Jurassic Period, around the time when the first true birds are thought to have appeared. The creature had feathers and seems to have been black with white stripes and displayed a distinctive orange feather crest on the crown of its head. It is not clear whether Anchiornis could fly or glide. The research is published in the journal Nature Communications.

Zhou B.,Harbin Institute of Technology | Duan G.-R.,Harbin Institute of Technology | Lam J.,University of Hong Kong
Automatica | Year: 2010

By exploring some geometric properties of the logarithmic quantizer and using the fact that the logarithmic quantizer is sector bounded and nondecreasing, this paper presents a new approach to the stability analysis of quantized feedback control systems. Our method is based on Tsypkin-type Lyapunov functions that have been widely used in absolute stability analysis problems. The results are expressed in linear matrix inequalities (LMIs) and are valid for both single-input and multiple-input discrete-time linear systems with a logarithmic quantizer. Both theoretical analysis and numerical examples show that the results in this paper are generally less conservative than those in the quadratic framework. © 2009 Elsevier Ltd. All rights reserved.

Ali J.R.,University of Hong Kong | Krause D.W.,State University of New York at Stony Brook
Journal of Biogeography | Year: 2011

Aim To evaluate the Gunnerus Ridge land-bridge hypothesis, which postulates a Late Cretaceous causeway between eastern Antarctica and southern Madagascar allowing the passage of terrestrial vertebrates. Location Eastern Antarctica, southern Indian Ocean, Madagascar. Methods The review involves palaeogeographical modelling, which draws upon geological and geophysical data, bathymetric charts, and plate tectonic reconstructions, and the evaluation of stratigraphically calibrated phylogenetic analyses to document ghost lineages of select taxa. Results The available geological and geophysical evidence indicates that eastern Antarctica's Gunnerus Ridge and southern Madagascar were separated for the entire Late Cretaceous by a vast marine expanse. In the mid-Late Cretaceous, the gap was probably punctuated by land on two intervening physiographical highs, the northern Madagascar Plateau and Conrad Rise, the latter of which, although probably large, was still separated from Antarctica's Riiser-Larsen Peninsula by c.1600km. Recent, stratigraphically calibrated phylogenies including large, terrestrial end-Cretaceous vertebrate taxa of Madagascar and the Indian subcontinent reveal long ghost lineages that extended into the Early Cretaceous. Main conclusions The view that Antarctica and Madagascar were connected by a long causeway between the Gunnerus Ridge and southern Madagascar in the Late Cretaceous, and that terrestrial vertebrates were able to colonize new frontiers using this physiographical feature, is almost certainly incorrect, as was previously demonstrated for the purported causeway between Antarctica and the Indian subcontinent across the Kerguelen Plateau. Connection across mainland Africa to account for the close relationships of several fossil and extant vertebrate taxa of Indo-Madagascar and South America is another option, although this too lacks credibility. We conclude that (1) throughout the Late Cretaceous there was no intervening, continuous causeway through Antarctica and associated land bridges between South America to the west and Indo-Madagascar to the east; and (2) mid- to large-sized, obligate terrestrial forms (e.g. abelisauroid theropod and titanosaurian sauropod dinosaurs and notosuchian crocodyliforms) gained broad distribution across Gondwanan land masses prior to fragmentation and were isolated on Indo-Madagascar before the end of the Early Cretaceous. © 2011 Blackwell Publishing Ltd.

Li C.,University of Hong Kong | Guo L.,Institute of Systems Science
IEEE Transactions on Automatic Control | Year: 2011

In this technical note, we will investigate the maximum capability and limitations of the feedback mechanism in globally stabilizing a basic class of discrete-time nonlinearly parameterized dynamical systems with multiple unknown parameters. Both possibility and impossibility theorems together with a fairly complete characterization on the capability of feedback will be presented. It will be seen that to characterize the feedback capability, the growth rates of the sensitivity functions of the nonlinear dynamics with respect to the uncertain parameters play a crucial role, and a suitable decomposition of the family of the nonlinearly parameterized functions in question turns out to be necessary. © 2006 IEEE.

Gao H.,Harbin Institute of Technology | Fei Z.,Washington University in St. Louis | Lam J.,University of Hong Kong | Du B.,University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2011

This technical note studies the problem of exponential estimates for Markovian jump systems with mode-dependent interval time-varying delays. A novel LyapunovKrasovskii functional (LKF) is constructed with the idea of delay partitioning, and a less conservative exponential estimate criterion is obtained based on the new LKF. Illustrative examples are provided to show the effectiveness of the proposed results. © 2010 IEEE.

Kong A.K.H.,National Tsing Hua University | Hui C.Y.,Chungnam National University | Cheng K.S.,University of Hong Kong
Astrophysical Journal Letters | Year: 2010

We report the discovery of gamma-ray emission from the Galactic globular cluster (GC) Terzan 5 using data taken with the Fermi Gamma-ray Space Telescope, from 2008 August 8 to 2010 January 1. Terzan 5 is clearly detected in the 0.5-20 GeV band by Fermi at ∼27σ level. This makes Terzan 5 the second gamma-ray-emitting GC seen by Fermi after 47 Tuc. The energy spectrum of Terzan 5 is best represented by an exponential cutoff power-law model, with a photon index of ∼1.9 and a cutoff energy at ∼3.8 GeV. By comparing Terzan 5 to 47 Tuc, we suggest that the observed gamma-ray emission is associated with millisecond pulsars and is either from the magnetospheres or inverse Compton scattering between the relativistic electrons/positrons in the pulsar winds and the background soft photons from the Galactic plane. Furthermore, it is suggestive that the distance to Terzan 5 is less than 10 kpc and >10 GeV photons can be seen in the future. © 2010. The American Astronomical Society. All rights reserved..

Zhang L.,Harbin Institute of Technology | Lam J.,University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2010

This technical note is concerned with exploring a new approach for the analysis and synthesis for Markov jump linear systems with incomplete transition descriptions. In the study, not all the elements of the transition rate matrices (TRMs) in continuous-time domain, or transition probability matrices (TPMs) in discrete-time domain are assumed to be known. By fully considering the properties of the TRMs and TPMs, and the convexity of the uncertain domains, necessary and sufficient criteria of stability and stabilization are obtained in both continuous and discrete time. Numerical examples are used to illustrate the results. © 2006 IEEE.

Wang W.,University of Hong Kong | Zhou M.-F.,University of Hong Kong | Yan D.-P.,China University of Geosciences | Li J.-W.,Wuhan University
Precambrian Research | Year: 2012

The Sibao Group on the southeastern margin of the Yangtze Block of South China is composed mainly of flysch turbidites up to ca. 4000m thick. Sandstones from the Sibao Group have intermediate to high SiO 2 (58.6-80.0wt%, average 68.2wt%) and Al 2O 3 wt% (7.4-20.6wt%, average 15wt%), typical of immature lithic varieties. Both sandstones and mudstones contain high K 2O (1.41-6.28wt%) but extremely low Na 2O (0.03-1.49wt%). Positive correlations between Al 2O 3 and Fe 2O 3 (T), TiO 2, MgO and K 2O, significant depletion of Ca, Na and Sr relative to upper continental crust and high PIA and pre-metasomatism CIA values suggest that intensive chemical weathering of the source area. Variable Cr/Th (3.9-37.0) and Co/Th (0.2-3.2) ratios indicate a source with predominant felsic and minor mafic components. Discrimination diagrams involving Ti, Al, Fe, La, Th, Sc, Hf and Co reveal the source with multiple lithologies consisting mainly of TTG-like, granitic, andesitic and felsic volcanic rocks.Predominant detrital zircons have Neoproterozoic ages from 822 to 980Ma, whereas the remaining zircons define two age groups at 1.35-2.22Ga and 2.32-2.86Ga. Twenty-six of the youngest grains have a weighted mean age of 835.3±3.6Ma, tentatively interpreted as the maximum depositional age of the Sibao Group. Neoproterozoic zircon grains have variable 177Hf/ 176Hf ratios (0.281194 to 0.282564) and e{open} Hf(t) values (-35.9 to 9.8), indicative of the involvement of juvenile and ancient recycled components. The 1.4 and 1.8Ga zircon grains have variable 177Hf/ 176Hf ratios (0.280947-0.281874), probably reflecting the growth of the supercontinent Columbia and suggesting that the Yangtze Block was separated from Columbia as an independent terrane at around 1.4Ga. The complicated provenance involving felsic to intermediate rocks and Neoproterozoic juvenile to Neoarchean mature materials suggests that the Neoproterozoic Sibao Group was deposited in a back-arc foreland basin related to the northward (present coordinate) subduction of an oceanic lithosphere beneath the southeastern Yangtze Block. © 2011 Elsevier B.V.

Chau M.,University of Hong Kong | Xu J.,Bentley University
MIS Quarterly: Management Information Systems | Year: 2012

The increasing popularity of Web 2.0 has led to exponential growth of user-generated content in both volume and significance. One important type of user-generated content is the blog. Blogs encompass useful information (e.g., insightful product reviews and information-rich consumer communities) that could potentially be a gold mine for business intelligence, bringing great opportunities for both academic research and business applications. However, performing business intelligence on blogs is quite challenging because of the vast amount of information and the lack of commonly adopted methodology for effectively collecting and analyzing such information. In this paper, we propose a framework for gathering business intelligence from blogs by automatically collecting and analyzing blog contents and bloggers' interaction networks. Through a system developed using the framework, we conducted two case studies with one case focusing on a consumer product and the other on a company. Our case studies demonstrate how to use the framework and appropriate techniques to effectively collect, extract, and analyze blogs related to the topics of interest, reveal novel patterns in the blogger interactions and communities, and answer important business intelligence questions in the domains. The framework is sufficiently generic and can be applied to any topics of interest, organizations, and products. Future academic research and business applications related to the topics examined in the two cases can also be built using the findings of this study.

Feng Z.,University of Hong Kong | Lam J.,University of Hong Kong | Gao H.,Harbin Institute of Technology
Automatica | Year: 2011

In this paper, the problem of delay-dependent α-dissipativity analysis is investigated for continuous-time singular systems with time-delay. Using the delay partitioning technique, sufficient conditions are established in terms of linear matrix inequalities (LMIs), which guarantees a singular system to be admissible and strictly (Q,S,R)-α-dissipative. In addition to delay dependence, the obtained results are also dependent on the parameter α. Moreover, the results of H∞ performance analysis and passivity analysis are unified from the dissipative analysis results. The results developed in this paper are less conservative than existing ones in the literature, which are illustrated by several examples. © 2011 Elsevier Ltd. All rights reserved.

Zhang Z.M.,Chinese Academy of Geological Sciences | Dong X.,Chinese Academy of Geological Sciences | Santosh M.,Kochi University | Santosh M.,China University of Geosciences | Zhao G.C.,University of Hong Kong
Gondwana Research | Year: 2014

The Lhasa terrane in southern Tibet is composed of Precambrian crystalline basement, Paleozoic to Mesozoic sedimentary strata and Paleozoic to Cenozoic magmatic rocks. This terrane has long been accepted as the last crustal block to be accreted with Eurasia prior to its collision with the northward drifting Indian continent in the Cenozoic. Thus, the Lhasa terrane is the key for revealing the origin and evolutionary history of the Himalayan-Tibetan orogen. Although previous models on the tectonic development of the orogen have much evidence from the Lhasa terrane, the metamorphic history of this terrane was rarely considered. This paper provides an overview of the temporal and spatial characteristics of metamorphism in the Lhasa terrane based mostly on the recent results from our group, and evaluates the geodynamic settings and tectonic significance. The Lhasa terrane experienced multistage metamorphism, including the Neoproterozoic and Late Paleozoic HP metamorphism in the oceanic subduction realm, the Early Paleozoic and Early Mesozoic MP metamorphism in the continent-continent collisional zone, the Late Cretaceous HT/MP metamorphism in the mid-oceanic ridge subduction zone, and two stages of Cenozoic MP metamorphism in the thickened crust above the continental subduction zone. These metamorphic and associated magmatic events reveal that the Lhasa terrane experienced a complex tectonic evolution from the Neoproterozoic to Cenozoic. The main conclusions arising from our synthesis are as follows: (1) The Lhasa block consists of the North and South Lhasa terranes, separated by the Paleo-Tethys Ocean and the subsequent Late Paleozoic suture zone. (2) The crystalline basement of the North Lhasa terrane includes Neoproterozoic oceanic crustal rocks, representing probably the remnants of the Mozambique Ocean derived from the break-up of the Rodinia supercontinent. (3) The oceanic crustal basement of North Lhasa witnessed a Late Cryogenian (~. 650. Ma) HP metamorphism and an Early Paleozoic (~. 485. Ma) MP metamorphism in the subduction realm associated with the closure of the Mozambique Ocean and the final amalgamation of Eastern and Western Gondwana, suggesting that the North Lhasa terrane might have been partly derived from the northern segment of the East African Orogen. (4) The northern margin of Indian continent, including the North and South Lhasa, and Qiangtang terranes, experienced Early Paleozoic magmatism, indicating an Andean-type orogeny that resulted from the subduction of the Proto-Tethys Ocean after the final amalgamation of Gondwana. (5) The Lhasa and Qiangtang terranes witnessed Middle Paleozoic (~. 360. Ma) magmatism, suggesting an Andean-type orogeny derived from the subduction of the Paleo-Tethys Ocean. (6) The closure of Paleo-Tethys Ocean between the North and South Lhasa terranes and subsequent terrane collision resulted in the formation of Late Permian (~. 260. Ma) HP metamorphic belt and Triassic (220. Ma) MP metamorphic belt. (7) The South Lhasa terrane experienced Late Cretaceous (~. 90. Ma) Andean-type orogeny, characterized by the regional HT/MP metamorphism and coeval intrusion of the voluminous Gangdese batholith during the northward subduction of the Neo-Tethyan Ocean. (8) During the Early Cenozoic (55-45. Ma), the continent-continent collisional orogeny has led to the thickened crust of the South Lhasa terrane experiencing MP amphibolite-facies metamorphism and syn-collisional magmatism. (9) Following the continuous continent convergence, the South Lhasa terrane also experienced MP metamorphism during Late Eocene (40-30. Ma). (10) During Mesozoic and Cenozoic, two different stages of paired metamorphic belts were formed in the oceanic or continental subduction zones and the middle and lower crust of the hanging wall of the subduction zone. The tectonic imprints from the Lhasa terrane provide excellent examples for understanding metamorphic processes and geodynamics at convergent plate boundaries. © 2012 International Association for Gondwana Research.

Siu C.-W.,University of Hong Kong | Lip G.Y.H.,University of Birmingham | Lam K.-F.,University of Hong Kong | Tse H.-F.,University of Hong Kong
Heart Rhythm | Year: 2014

Background Current risk schemes to predict ischemic stroke and intracranial hemorrhage (ICH) in atrial fibrillation (AF) are derived primarily using a Caucasian population. Objective The purpose of this study was to describe the risk of ischemic stroke and ICH in a large contemporary "real world" cohort of Chinese AF patients in Hong Kong with detailed long-term follow-up. Methods This observational study used a hospital-based cohort of Chinese patients with nonvalvular AF. Results Among 9727 patients with nonvalvular AF (age 76.9 ± 12.5 years, 52.1% female), 3881 patients (39.9%) did not receive antithrombotic therapy, 3934 patients (40.4%) were taking aspirin, and 1912 (19.7%) were taking warfarin. After mean follow-up of 3.19 years, 847 patients (21.8%) without antithrombotic therapy developed ischemic strokes (annual risk 9.28%, 95% confidence interval [CI] 8.89%-9.70%). There was a progressively increase in annual risk of ischemic stroke with increasing CHADS2 and CHA2DS2VASc scores. The c-statistics revealed that CHA2DS2-VASc scores (0.525, 95% CI 0.509-0.541, P =.017) was better than CHADS2 scores (0.506, 95% CI 0.490-0.522, P =.584) in predicting ischemic stroke. Use of aspirin and of warfarin were associated with reduced annual risk of ischemic stroke by 18.7% and 52.7%, respectively (P <.05). The annual incidence of ICH in patients taking aspirin and warfarin was 0.77% per year and 0.80% per year, respectively. The adjusted net clinical benefit favored warfarin over aspirin or no therapy for almost all Chinese AF patients CHA2DS2-VASc score 1. Conclusion Chinese AF patients are at high risk for ischemic stroke. Analysis of the net clinical benefit favors the use of warfarin over aspirin or no therapy for stroke prevention in a broad range of Chinese AF patients. © 2014 Heart Rhythm Society. All right sreserved.

News Article | August 22, 2016
Site: www.spie.org

A microsphere superlens is used to convert evanescent waves into propagating waves and provide an imaging efficiency that is 40 times higher than for atomic force microscopy. In general, existing microscopy methods can be separated into three categories, namely, optical microscopy, electron microscopy, and scanning probe microscopy (SPM). Optical microscopy provides a non-invasive, high-speed, relatively low-cost, and environmentally compatible technique for the observation of objects down to the sub-microscale. The imaging resolution of optical microscopy, however, is confined to about half of the illuminating wavelength (in the lateral dimensions), and is several times worse in the axial dimension because of the diffraction limit. Alternative, high-resolution microscopy methods in which the diffraction limit can be overcome are therefore required. In recent work, super-resolution fluorescence microscopes have been successfully advanced to nanoscale resolutions in life science studies.1–3 With these microscopes, however, there is a loss of structural information that restricts their potential applications in semiconductor wafer inspection, the exploration of nanoscale materials/structures, and the non-invasive study of dynamic processes.4, 5 Furthermore, there are few microscopy methods (except for SPM) with which super-resolution imaging can be achieved in all three dimensions, without the use of fluorescent dyes. Indeed, there are also some limitations that prevent the application of SPM in more research fields. Such limitations of SPM include the invasiveness (because of scanning tips), poor time efficiency, and tip (broadening) effects. In other studies, efforts have been made to overcome the lateral diffraction limit of microscopy techniques in a more convenient way. It has been demonstrated that dielectrics with micro- or wavelength-scale spherical structures can be used to realize sub-diffraction-limited resolution (from about 200–50nm).6, 7 Observations of sub-cellular structures8 and 75nm adenoviruses9 have also been successfully demonstrated with microsphere superlenses. When these lenses are combined with a scanning laser confocal microscope, they can be used to resolve structures with feature sizes of about 25nm.10 In our previous work, we showed that a microsphere superlens can be used to enhance the resolution—to the nanoscale—of a microendoscopy approach that was based on a graded-index lens.12 In our more recent work, we have demonstrated a new 3D super-resolution microscopy technique. This method—known as near-field assisted white-light interferometry (NFWLI)—is illustrated in Figure 1. For this approach, we take advantage of the topography acquisition capability of white-light interferometry and the lateral near-field imaging principles of the microsphere superlens.11 Figure 1. Schematic illustration of the near-field assisted white-light interferometry (NFWLI) technique. (a) The NFWLI system is constructed by integrating a microsphere superlens into a Linnik white-light interferometer. The system consists of an analyzer (A), quarter-waveplate (Q), beam splitter (BS), polarizing beam splitter (PBS), polarizer (P), Köhler illumination (KI), mirror (M), piezoelectric ceramic scanner (PZT), and two objectives (O1 and O2). (b) Image frames are recorded during PZT linear scanning along the light path, as indicated by the red arrow. (c) Analyses of the recorded interference images are used to construct the 3D morphology of the measured objects. (d) The final constructed (super-resolution) 3D morphology. Schematic illustration of the near-field assisted white-light interferometry (NFWLI) technique. (a) The NFWLI system is constructed by integrating a microsphere superlens into a Linnik white-light interferometer. The system consists of an analyzer (A), quarter-waveplate (Q), beam splitter (BS), polarizing beam splitter (PBS), polarizer (P), Köhler illumination (KI), mirror (M), piezoelectric ceramic scanner (PZT), and two objectives (O1 and O2). (b) Image frames are recorded during PZT linear scanning along the light path, as indicated by the red arrow. (c) Analyses of the recorded interference images are used to construct the 3D morphology of the measured objects. (d) The final constructed (super-resolution) 3D morphology. 11 In most situations, the vertical information for a sample cannot be constructed directly by analyzing interference images of evanescent waves (because of the lack of phase information along the vertical direction). In our NFWLI technique, however, we use a microsphere superlens to convert the evanescent waves into propagating waves. We also reconstruct the phase information along the vertical direction from the evanescent waves. By analyzing the recorded images that are generated by the interference of the converted propagating waves and the reference light beams, we can construct the morphology of a sample (with sub-diffraction-limited resolution) in all three dimensions. We have tested our NFWLI method by observing structures within central processing unit chips. These chips have lateral dimensions of about 50nm and a vertical dimension of about 10nm. We conducted these observations (see Figure 2) without the use of fluorescent dyes and within 25s, i.e., 40 times faster than for atomic force microscope (AFM) measurements. We find—see Figure 2(d–f)—that the profiles we obtained with our NFWLI technique are consistent, and that they are similar to those we obtained via AFM scanning. Our results also demonstrate that the NFWLI method can operate well in both air and in water. Figure 2. Examples of using NFWLI for the inspection of semiconductor chips. Observations are made of (a) 90nm features, (b) an array of nanodots, and (c) 65nm structures. Scanning electron microscope images (i), virtual images generated with a microsphere superlens (ii), atomic force microscope (AFM) scanning images (iii), and the 3D morphology constructed by NFWLI (iv) are shown in each case. (d–f) Comparisons of the cross sections—marked by the blue and red lines in (a–c)—obtained via AFM scanning and NFWLI. Examples of using NFWLI for the inspection of semiconductor chips. Observations are made of (a) 90nm features, (b) an array of nanodots, and (c) 65nm structures. Scanning electron microscope images (i), virtual images generated with a microsphere superlens (ii), atomic force microscope (AFM) scanning images (iii), and the 3D morphology constructed by NFWLI (iv) are shown in each case. (d–f) Comparisons of the cross sections—marked by the blue and red lines in (a–c)—obtained via AFM scanning and NFWLI. 11 In summary, we have developed a new technique—near-field assisted white-light interferometry—that provides significant advantages over standard scanning probe microscopy for 3D nanoscale morphology profiling. For example, our NFWLI approach has a much improved time efficiency for large-area nanoscale morphology acquisition (i.e., with a field of view that is on the order of micrometers). In addition, our method is non-invasive because the microsphere superlens does not need to be in direct contact with the samples, and it produces reduced repeatability errors (i.e., it does not require scanning probe tips that may wear out during repeated scans and thus cause surface profiling errors). We believe that NFWLI therefore has great potential as a practical 3D super-resolution microscopy method for label-free, high-speed, non-invasive, and environmentally compatible imaging. Indeed, all these properties should facilitate 3D nanoscale imaging of integrated circuit devices, nanomaterials, and biological entities (e.g., cell membranes, viruses, or biomolecules) in the future. The observable area of NFWLI, however, is currently confined by the microsphere's field of view, and we are therefore currently exploring several effective methods to overcome this limitation. Department of Mechanical and Biomedical Engineering City University of Hong Kong Department of Mechanical and Biomedical EngineeringCity University of Hong Kong 1. R. Schmidt, C. A. Wurm, S. Jakobs, J. Engelhardt, A. Egner, S. W. Hell, Spherical nanosized focal spot unravels the interior of cells, Nat. Methods 5, p. 539-544, 2008. 2. M. G. L. Gustafsson, L. Shao, P. M. Carlton, C. J. R. Wang, I. N. Golubovskaya, W. Z. Cande, D. A. Agard, J. W. Sedat, Three-dimensional resolution doubling in wide-field fluorescence microscopy by structured illumination, Biophys. J. 94, p. 4957-4970, 2008. 6. J. Y. Lee, B. H. Hong, W. Y. Kim, S. K. Min, Y. Kim, M. V. Jouravlev, R. Bose, et al., Near-field focusing and magnification through self-assembled nanoscale spherical lenses, Nature 460, p. 498-501, 2009. 10. Y. Yan, L. Li, C. Feng, W. Guo, S. Lee, M. Hong, Microsphere-coupled scanning laser confocal nanoscope for sub-diffraction-limited imaging at 25nm lateral resolution in the visible spectrum, ACS Nano 8, p. 1809-1816, 2014.

Most studies of global climate change attempt to predict what might happen to the Earth as temperatures rise in future. A new study representing an international collaboration by ecologists and conservation biologists shows that global changes in climate have already impacted every aspect of life on Earth, from genes to entire ecosystems. It was published in the prestigious journal Science on November 10, 2016. The research team, led by the University of Florida and with participation from the University of Hong Kong, showed that of a total of 94 ecological processes evaluated globally, 82% of them showed evidence of impact from climate change. Land, freshwater and marine ecosystems and species have all been all affected, and consequential impacts on people could range from increased pests and disease outbreaks, to unpredictable changes in fisheries and decreasing agriculture yields. This study is released at an important moment as it helps shed light on the need to plan practically for the implementation of the Paris agreement on climate change which entered into force last Friday (November 4, 2016). The Paris agreement marked the first time that governments have agreed binding limits to keep global warming well-below two degrees Celsius above pre-industrial levels. That agreement was overdue: the World Meteorological Organization announced on Wednesday (November 9, 2016) that the 2011-15 had been the five hottest years on record, with temperatures peaking in 2015. "We now have evidence that, with only a ~1 degree Celsius of warming globally, major impacts are already being felt in natural systems," said study lead author Dr Brett Scheffers of the University of Florida. "Genes are changing, species' physiology and physical features such as body size are changing, species are moving and we see clear signs of entire ecosystems under stress, all in response to changes in climate on land and in the ocean". "Some people didn't expect this level of change for decades," said co-author Dr James Watson, of the University of Queensland in Australia. "The impacts of climate change are being felt with no ecosystem on Earth being spared. It is no longer sensible to consider climate change as a concern just for the future." "The paper shows that there are winners and losers under global warming: the geographic ranges of some species have expanded while others have contracted, and timing of breeding and other seasonal events have shifted," said co-author, Professor David Dudgeon, Chair of Ecology & Biodiversity and Director of the School of Biological Sciences at the University of Hong Kong. This study has significant implications for Hong Kong. According to Professor Dudgeon, we can envisage that endemic species - found nowhere else but Hong Kong - will have little chance to make compensatory range shifts in response to climate change. The Hong Kong paradise fish and the short-legged toad are examples of species that would be unable to adjust their ranges due to intense urbanization around the sites they occupy currently. If conditions change, they must adapt or perish. The Hong Kong newt, which breeds only during the coolest months of the year, would also likely fall victim to warming since, in future, winter temperatures might not fall sufficiently to permit reproduction by this species which is, already, globally near-threatened. Mountain-top animals such as the giant spiny frog, already mainly confined to streams near the summit of Tai Mo Shan and globally vulnerable to extinction, would have nowhere to go as the climate warms. "The new paper shows a pervasive ecological finger print of only 1 degree Celsius of global warming. This will not be beneficial for local species of conservation concern." On a global scale, Dudgeon added, "we face an uncertain ecological future as the temperature continues to rise, especially if warming exceeds the 1.5-degree boundary incorporated in the Paris climate-change agreements that came into force last week. Such warming would put at risk biodiversity and the ecosystem services delivered by nature that benefit humans". Dudgeon concluded: "To put it bluntly, climate change is already happening, and it is altering ecological process and natural systems everywhere. We must to do more to limit carbon emissions and prevent further warming." DOI for this paper, The broad footprint of climate change from genes to biomes to people, is 10.1126/science.aaf7671

Ryutaro Goto, postdoctoral fellow in Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, and Hiroshi Ishikawa, amateur malacologist in Japan, have their paper, describing the new species, published in the open access journal ZooKeys. The new species, named Borniopsis mortoni (Galeommatoidea), was discovered in mudflats at the mouth of the Souzu River, southwestern Shikoku Island, Japan. This bivalve has tiny brownish shells (up to 4.1 mm in length). The species lives attached by both its foot and byssal threads to the body surface of the earthworm-like sea cucumber Patinapta ooplax (Synaptidae). Individuals of B. mortoni are often found on the same host, yet sometimes there could be more than 10 individuals existing side-by-side. The new species is dedicated to a famous British malacologist Brian Morton, emeritus professor of University of Hong Kong. He has described many interesting Pseudopythina species from mudflats in Hong Kong, now assigned to the genus Borniopsis. Host sea cucumbers burrow in mudflats. Most likely, the B. mortoni bivalve uses the host burrows as shelter from predators. The new species is one of the smallest species in this genus. With the burrow of the host sea cucumber being very narrow, the small body size of B. mortoni is probably a corresponding adaptation. Explore further: A new species of gall makers in the aphid genus of plant lice was found in China More information: Ryutaro Goto et al, Borniopsis mortoni sp. n. (Heterodonta, Galeommatoidea, Galeommatidae sensu lato), a new bivalve commensal with a synaptid sea cucumber from Japan, ZooKeys (2016). DOI: 10.3897/zookeys.615.8125

Chan J.K.Y.,University of Hong Kong | Wong M.H.,Hong Kong Baptist University
Science of the Total Environment | Year: 2013

This paper reviews the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in different environmental media, human body burdens and health risk assessment results at e-waste recycling sites in China. To provide an indication of the seriousness of the pollution levels in the e-waste recycling sites in China, the data are compared with guidelines and available existing data for other areas. The comparison clearly shows that PCDD/Fs derived from the recycling processes lead to serious pollution in different environmental compartments (such as air, soil, sediment, dust and biota) and heavy body burdens. Of all kinds of e-waste recycling operations, open burning of e-waste and acid leaching activities are identified as the major sources of PCDD/Fs. Deriving from the published data, the estimated total exposure doses via dietary intake, inhalation, soil/dust ingestion and dermal contact are calculated for adults, children and breast-fed infants living in two major e-waste processing locations in China. The values ranged from 5.59 to 105.16. pg. WHO-TEQ/kg. bw/day, exceeding the tolerable daily intakes recommended by the WHO (1-4. pg. WHO-TEQ/kg. bw/day). Dietary intake is the most important exposure route for infants, children and adults living in these sites, contributing 60-99% of the total intakes. Inhalation is the second major exposure route, accounted for 12-30% of the total exposure doses of children and adults. In order to protect the environment and human health, there is an urgent need to control and monitor the informal e-waste recycling operations. Knowledge gaps, such as comprehensive dietary exposure data, epidemiological and clinical studies, body burdens of infants and children, and kinetics about PCDD/Fs partitions among different human tissues should be addressed. © 2012 Elsevier B.V.

Chavanis P.-H.,French National Center for Scientific Research | Harko T.,University of Hong Kong
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We analyze the possibility that due to their superfluid properties some compact astrophysical objects may contain a significant part of their matter in the form of a Bose-Einstein condensate. To study the condensate we use the Gross-Pitaevskii equation with arbitrary nonlinearity. By introducing the Madelung representation of the wave function, we formulate the dynamics of the system in terms of the continuity and hydrodynamic Euler equations. The nonrelativistic and Newtonian Bose-Einstein gravitational condensate can be described as a gas, whose density and pressure are related by a barotropic equation of state. In the case of a condensate with quartic nonlinearity, the equation of state is polytropic with index one. In the framework of the Thomas-Fermi approximation the structure of the Newtonian gravitational condensate is described by the Lane-Emden equation, which can be exactly solved. The case of the rotating condensate is briefly discussed. General relativistic configurations with quartic nonlinearity are studied numerically with both nonrelativistic and relativistic equations of state, and the maximum mass of the stable configuration is determined. Condensates with particle masses of the order of two neutron masses (Cooper pair) and scattering length of the order of 10-20fm have maximum masses of the order of 2M, maximum central density of the order of 0.1-0.3×1016g/cm3 and minimum radii in the range of 10-20km. In this way we obtain a large class of stable astrophysical objects, whose basic astrophysical parameters (mass and radius) sensitively depend on the mass of the condensed particle, and on the scattering length. We also propose that the recently observed neutron stars with masses in the range of 2-2.4M are Bose-Einstein condensate stars. We discuss the connection of our results with previous boson star models based on scalar field theory. © 2012 American Physical Society.

Shellnutt J.G.,Academia Sinica, Taiwan | Jahn B.-M.,Academia Sinica, Taiwan | Zhou M.-F.,University of Hong Kong
Lithos | Year: 2011

In the Panxi region of the Late Permian (~260Ma) Emeishan large igneous province (ELIP) there is a bimodal assemblage of mafic and felsic plutonic rocks. Most Emeishan granitic rocks were derived by differentiation of basaltic magmas (i.e. mantle-derived) or by mixing between crustal melts and primary basaltic magmas (i.e. hybrid). The Yingpanliangzi granitic pluton within the city of Panzhihua intrudes Sinian (~600Ma) marbles and is unlike the mantle-derived or hybrid granitic rocks. The SHRIMP zircon U-Pb ages of the Yingpanliangzi pluton range from 259±8Ma to 882±22Ma. Younger ages are found on the zircon rims whereas older ages are found within the cores. Field relationships and petrography indicate that the Yingpanliangzi pluton must be <600Ma, therefore the older zircons are interpreted to represent the protolith age whereas the younger analyses represent zircon re-crystallization during emplacement. The Yingpanliangzi granites are metaluminous and have negative Ta-NbPM anomalies, low εNd(260 Ma) values (-3.9 to -4.4), and high ISr (0.71074 to 0.71507) consistent with a crustal origin. The recognition of a crustally-derived pluton along with mantle-derived and mantle-crust hybrid plutons within the Panxi region of the ELIP is evidence for a complete spectrum of sources. As a consequence, the types of Panxi granitoids can be distinguished according to their ASI, Eu/Eu*, εNd(T), εHf(T), TZr(°C) and Nb-TaPM values. The diverse granitic magmatism during the evolution of the ELIP from ~260Ma to ~252Ma demonstrates the complexity of crustal growth associated with LIPs. © 2010 Elsevier B.V.

Deng L.,Hong Kong Baptist University | Tavares N.J.,University of Hong Kong
Computers and Education | Year: 2013

The present paper documents a qualitative study that examines the motivating and inhibiting factors that influenced students' engagement in online discussions via Moodle and Facebook. The data was collected through individual interviews with 14 pre-service teachers. Using the Activity Theory as a lens, the study reveals a set of factors concerning the technical tools, subjective perceptions, goals of online discussion, social presence within a community, rules for participation, and roles of the participants that affect their online engagement patterns. The findings of the study inform educators and software designers of how online discussions can be better promoted among students, and how a web-based environment more conducive to learning can be created. © 2013 Elsevier Ltd. All rights reserved.

News Article | March 9, 2016
Site: phys.org

Globally declining fish populations are a frequently cited ecological and commercial calamity, but relatively little attention has been paid to the specific threats faced by fish that gather and spawn in large groups, says Yvonne Sadovy, writing in an article for BioScience. The marine scientist, affiliated with the University of Hong Kong and Science and Conservation of Fish Aggregations (SCRFA), outlines the challenges unique to these populations. "Many aggregating species face growing threats to their populations from increasing harvest and lack of effective management," she says. Appearing in temporarily high abundances, the fish are particularly vulnerable to overexploitation as a result of both increased catchability and lethal and nonlethal biological factors. According to Sadovy, aggregations in small-scale fisheries in particular could be dangerously overfished by only a few active boats, but large-scale industrial fisheries are also susceptible. The author also describes how changing economic conditions could contribute to rapid species declines. Many exploited fish populations were once safeguarded from collapses by costs of fishing that rose as fish numbers declined. Given the high catchability of aggregate spawners and consumers' growing ability to pay premium prices for desirable species, this safety valve is vanishing. Instead, fishing pressure could be ramped up, leading to a "downward spiral toward extinction." The Chinese bahaba is a clear example. Insufficient or inappropriate management contributes to the problem, says the author: "Fisheries management was long (and largely still is) based on the concept of 'stocks,' with management units and monitoring typically treating localized demographic effects and local overfishing as unimportant." Such approaches may neglect the complex migratory dynamics and life histories of many individual populations, reports the author. Also, biological factors can increasingly compromise reproduction in aggregations as fish numbers decline. Sadovy does see an ongoing role for fishing of aggregate-spawning species, which she describes as being of great economic and food security value globally, but this can be continued only "if it is done right" and if management is truly precautionary. In cases where insufficient management and enforcement are a problem, she proposes that "no fishing of spawning aggregations should occur until appropriate measures are implemented to ensure their sustainable use." Explore further: Twenty of world's 162 grouper species threatened with extinction

Gong T.,University of Hong Kong | Shuai L.,Johns Hopkins University
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

Joint attention (JA) is important to many social, communicative activities, including language, and humans exhibit a considerably high level of JA compared with non-human primates. We propose a coevolutionary hypothesis to explain this degree-difference in JA: once JA started to aid linguistic comprehension, along with language evolution, communicative success (CS) during cultural transmission could enhance the levels of JA among language users. We illustrate this hypothesis via a multi-agent computational model, where JA boils down to a genetically transmitted ability to obtain non-linguistic cues aiding comprehension. The simulation results and statistical analysis show that: (i) the level of JA is correlated with the understandability of the emergent language; and (ii) CS can boost an initially low level of JA and 'ratchet' it up to a stable high level. This coevolutionary perspective helps explain the degree-difference in many language-related competences between humans and non-human primates, and reflects the importance of biological evolution, individual learning and cultural transmission to language evolution. © 2012 The Royal Society.

Wang K.,Wuhan University | Choi S.H.,University of Hong Kong
Computers and Operations Research | Year: 2014

Flexible flow shop scheduling problems are NP-hard and tend to become more complex when stochastic uncertainties are taken into consideration. This paper presents a novel decomposition-based holonic approach (DBHA) for minimising the makespan of a flexible flow shop (FFS) with stochastic processing times. The proposed DBHA employs autonomous and cooperative holons to construct solutions. When jobs are released to an FFS, the machines of the FFS are firstly grouped by a neighbouring K-means clustering algorithm into an appropriate number of cluster holons, based on their stochastic nature. A scheduling policy, determined by the back propagation networks (BPNs), is then assigned to each cluster holon for schedule generation. For cluster holons of a low stochastic nature, the Genetic Algorithm Control (GAC) is adopted to generate local schedules in a centralised manner; on the other hand, for cluster holons of a high stochastic nature, the Shortest Processing Time Based Contract Net Protocol (SPT-CNP) is applied to conduct negotiations for scheduling in a decentralised manner. The combination of these two scheduling policies enables the DBHA to achieve globally good solutions, with considerable adaptability in dynamic environments. Computation results indicate that the DBHA outperforms either GAC or SPT-CNP alone for FFS scheduling with stochastic processing times. © 2013 Elsevier Ltd.

Choi S.H.,University of Hong Kong | Wang K.,Wuhan University
Computers and Industrial Engineering | Year: 2012

Flexible flow shop scheduling problems are NP-hard and tend to become more complex when stochastic uncertainties are taken into consideration. Although some methods have been developed to address such problems, they remain inherently difficult to solve by any single approach. This paper presents a novel decomposition-based approach (DBA), which combines both the shortest processing time (SPT) and the genetic algorithm (GA), to minimizing the makespan of a flexible flow shop (FFS) with stochastic processing times. In the proposed DBA, a neighbouring K-means clustering algorithm is developed to firstly group the machines of an FFS into an appropriate number of machine clusters, based on their stochastic nature. Two optimal back propagation networks (BPN), corresponding to the scenarios of simultaneous and non-simultaneous job arrivals, are then selectively adopted to assign either SPT or GA to each machine cluster for sub-schedule generation. Finally, an overall schedule is generated by integrating the sub-schedules of machine clusters. Computation results show that the DBA outperforms SPT and GA alone for FFS scheduling with stochastic processing times. © 2012 Elsevier Ltd. All rights reserved.

Wang C.Y.,CAS Guangzhou Institute of Geochemistry | Zhou M.-F.,University of Hong Kong
Mineralium Deposita | Year: 2013

The Hongge magmatic Fe-Ti-V oxide deposit in the Panxi region, SW China, is hosted in a layered mafic-ultramafic intrusion. This 2.7-km-thick, lopolith-like intrusion consists of the lower, middle, and upper zones, which are composed of olivine clinopyroxenite, clinopyroxenite, and gabbro, respectively. Abundant Fe-Ti oxide layers mainly occur in the middle zone and the lower part of the upper zone. Fe-Ti oxides include Cr-rich and Cr-poor titanomagnetite and granular ilmenite. Cr-rich titanomagnetite is commonly disseminated in the olivine clinopyroxenite of the lower parts of the lower and middle zones and contains 1.89 to 14.9 wt% Cr2O3 and 3.20 to 16.2 wt% TiO2, whereas Cr-poor titanomagnetite typically occurs as net-textured and massive ores in the upper middle and upper zones and contains much lower Cr2O3 (<0.4 wt%) but more variable TiO2 (0.11 to 18.2 wt%). Disseminated Cr-rich titanomagnetite in the ultramafic rocks is commonly enclosed in either olivine or clinopyroxene, whereas Cr-poor titanomangetite of the net-textured and massive ores is mainly interstitial to clinopyroxene and plagioclase. The lithology of the Hongge intrusion is consistent with multiple injections of magmas, the lower zone being derived from a single pulse of less differentiated ferrobasaltic magma and the middle and upper zones from multiple pulses of more differentiated magmas. Cr-rich titanomagnetite in the disseminated ores of the lower and middle zones is interpreted to represent an early crystallization phase whereas clusters of Cr-poor titanomagnetite, granular ilmenite, and apatite in the net-textured ores of the middle and upper zones are thought to have formed from an Fe-Ti-(P)-rich melt segregated from a differentiated ferrobasaltic magma as a result of liquid immiscibility. The dense Fe-Ti-(P)-rich melt percolated downward through the underlying silicate crystal mush to form net-textured and massive Fe-Ti oxide ores, whereas the coexisting Si-rich melt formed the overlying plagioclase-rich rocks in the intrusion. © 2013 Springer-Verlag Berlin Heidelberg.

Zhao J.-H.,Wuhan University | Zhou M.-F.,University of Hong Kong
Precambrian Research | Year: 2013

The southeastern Yangtze Block, South China, contains voluminous late Neoproterozoic felsic plutonic rocks and minor mafic-ultramafic volcanic rocks. Some ca. 830Ma lavas hosted in the Neoproterozoic strata have pillow structures and micro-spinifex textures and thus previously were considered as komatiitic basalts derived from a mantle plume. These rocks have high MgO (10.1-16.3wt%), variable CaO (6.57-11.2wt%), restricted Al2O3 (11.2-13.4wt%), and low TiO2 (0.50-0.61wt%), P2O5 (0.03-0.04wt%) and incompatible trace elements. They also have negative εNd (-5.4 to -2.9), and high 207Pb/204Pb (15.71-15.76) and initial 187Os/188Os ratios (0.1100-0.1931), indicating crustal contamination. The most primitive samples show arc-like trace elemental features which are characterized by enrichment of LREE and LILE relative to HFSE in the primitive-mantle-normalized trace-element diagrams, suggesting derivation from enriched mantle sources. PRIMELT2 modeling shows that their primary magmas were produced by about 30% partial melting of a fertile peridotite source having a mantle potential temperature of 1440-1500°C. Such a potential temperature is in agreement with the estimates for ambient mantle during the Neoproterozoic. These evidence suggest that the high-Mg basalts are similar to boninites and probably be part of an ophiolite assemblage. They were generated by melting of a hot ambient mantle source in relation to slab subduction during the amalgamation of the Yangtze and Cathaysia Blocks. © 2013 Elsevier B.V.

Wu D.Y.,Leighton Center | Lam K.F.,University of Hong Kong
Clinical Orthopaedics and Related Research | Year: 2015

Level of Evidence: Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.Conclusions: The osteodesis is a soft tissue nonosteotomy technique, and provided adequate deformity correction and improvement in AOFAS scores for patients with mild to moderate hallux valgus deformities, although a small number of the patients had postoperative stress fractures of the second ray develop. Future prospective studies should compare this technique with osteotomy techniques in terms of effectiveness of the correction, restoration of hallux function, complications, and long-term recurrence.Background: Although the etiology of hallux valgus is contested, in some patients it may be failure of the stabilizing soft tissue structures around the first ray of the foot. Because there is lack of effective soft tissue techniques, osteotomies have become the mainstream surgical approach to compensate for the underlying soft tissue deficiency; osteodesis, a soft tissue nonosteotomy technique, may be a third alternative, but its efficacy is unknown.Questions/purposes: We asked: (1) Can an osteodesis, a distal soft tissue technique, correct hallux valgus satisfactorily in terms of deformity correction and improvement in American Orthopaedic Foot and Ankle Society (AOFAS) score? (2) Is the effectiveness of an osteodesis affected by the patient’s age or deformity severity? (3) What complications are associated with this procedure?Methods: Between February and October 2010, we performed 126 operations to correct hallux valgus, of which 126 (100%) were osteodeses. Sixty-one patients (110 procedures) (87% of the total number of hallux valgus procedures) were available for followup at a minimum of 12 months (mean, 23 months; range, 12–38 months). This group formed our study cohort. During the study period, the general indications for this approach included failed conservative measures for pain relief and metatarsophalangeal angle greater than 20° or intermetatarsal angle greater than 9°. Intermetatarsal cerclage sutures were used to realign the first metatarsal and postoperative fibrosis was induced surgically between the first and second metatarsals to maintain its alignment. The radiologic first intermetatarsal angle, metatarsophalangeal angle, and medial sesamoid position were measured by Hardy and Clapham’s methods for deformity and correction evaluation. Clinical results were assessed by the AOFAS score.Results: The intermetatarsal angle was improved from a preoperative mean of 14° to 7° (p < 0.001; Cohen’s d = 1.8) at followup, the metatarsophalangeal angle from 31° to 18° (p < 0.001; Cohen’s d = 3.1), the medial sesamoid position from position 6 to 3 (p < 0.001; Cohen’s d = 2.4), and AOFAS hallux score from 68 to 96 points (p < 0.001). Neither patient age nor deformity severity affected the effectiveness of the osteodesis in correcting all three radiologic parameters; however, the deformities treated in this series generally were mild to moderate (mean intermetatarsal angle, 14°; range, 9°–22°). There were six stress fractures of the second metatarsal (5%), five temporary metatarsophalangeal joint medial subluxations all resolved in one month by the taping-reduction method without surgery, and six metatarsophalangeal joints with reduced dorsiflexion less than 60°. © 2014, The Association of Bone and Joint Surgeons®.

Zhou G.,Xi'an Jiaotong University | Wong W.-Y.,University of Hong Kong | Suo S.,Xi'an Jiaotong University
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2010

White organic light-emitting diodes (WOLEDs) offer a promising avenue to developing future energy-saving solid-state lighting sources because of their intrinsic characters such as low driving voltages, high brightness and efficiency, large area, etc. While commercialization of WOLEDs has attracted tremendous interest in both academic and industrial communities, the discovery of highly efficient phosphors opens up a good channel to meet this target. With the goal towards practical application, many design strategies, including new materials synthesis, judicious design of device configuration, wise management of charges/excitons in different active layers, development of sophisticated and low cost fabrication procedures, etc. have been put forward to achieve high efficiency, good white color stability and quality. In this review, the most recent progress and achievements in various research aspects of the phosphorescent WOLED is presented. Practical applications are enumerated and illustrated by specific examples. The major advances, ongoing challenges and future perspectives of this research frontier are also critically discussed. The present work provides valuable clues to the specialists in the field to develop new routes for future research development of WOLEDs. © 2011 Elsevier B.V.

Shan W.-Y.,University of Hong Kong | Lu H.-Z.,University of Hong Kong | Shen S.-Q.,University of Hong Kong
New Journal of Physics | Year: 2010

Two-dimensional (2D) effective continuous models are derived for the surface states and thin films of a three-dimensional topological insulator (3DTI). Starting from an effective model for 3DTI based on first-principles calculations (Zhang et al 2009 Nat. Phys. 5 438), we present solutions for both the surface states in a semi-infinite boundary condition and those in a thin film with finite thickness. The coupling between opposite topological surfaces and structure inversion asymmetry (SIA) gives rise to gapped Dirac hyperbolas with Rashba-like splittings in the energy spectrum. In addition, SIA leads to asymmetric distributions of wavefunctions for the surface states along the film growth direction, making some branches in the energy spectra much harder than others to probe by light. These features agree well with the recent angle-resolved photoemission spectra OfBi2Se3 films grown on SiC substrate (Zhang et al 2009 arXiv:0911.3706). More importantly, using the parameters fitted by experimental data, the result indicates that the thin film Bi2Se3 lies in the quantum spin Hall (QSH) region based on the calculation of the Chern number and Z2 invariant. In addition, strong SIA always tends to destroy the QSH state. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

So S.,University of Hong Kong
Internet and Higher Education | Year: 2016

Smartphones could be the fastest spreading technology in human history. These mobile devices change the way we communicate and enable mobile and ubiquitous learning at a different level. This study evaluated the use of mobile instant messaging tools to support teaching and learning in higher education. A total of 61 undergraduate students enrolled at a teacher-training institute in Hong Kong who have smartphones with WhatsApp were assigned into experimental and control groups. Besides the traditional classroom learning for both groups, the experimental group was also supported with bite-sized multimedia materials and teacher-student interaction via WhatsApp outside school hours. The participants of the control group used WhatsApp only for academic communication. Pre-test scores were used as the covariate. The marginal means on the post-test scores showed that the participants in the experimental group performed better than those in the control group. The intervention of WhatsApp improved the learning achievement of the participants. The strength of the intervention between the two groups was medium to large. A questionnaire designed by the author was administered at the end of the study. The participants showed positive perception and acceptance of the use of WhatsApp for teaching and learning. The participants slightly rejected the view that receiving instructional materials and questions outside school hours could interfere with their private lives. The typical usability issues on mobile learning were found to be valid. The experience learnt in this research was discussed. © 2016 Elsevier Inc.

Cowling B.J.,University of Hong Kong
Nature communications | Year: 2013

Influenza A viruses are believed to spread between humans through contact, large respiratory droplets and small particle droplet nuclei (aerosols), but the relative importance of each of these modes of transmission is unclear. Volunteer studies suggest that infections via aerosol transmission may have a higher risk of febrile illness. Here we apply a mathematical model to data from randomized controlled trials of hand hygiene and surgical face masks in Hong Kong and Bangkok households. In these particular environments, inferences on the relative importance of modes of transmission are facilitated by information on the timing of secondary infections and apparent differences in clinical presentation of secondary infections resulting from aerosol transmission. We find that aerosol transmission accounts for approximately half of all transmission events. This implies that measures to reduce transmission by contact or large droplets may not be sufficient to control influenza A virus transmission in households.

Ip C.K.M.,University of Hong Kong | Cheung A.N.Y.,University of Hong Kong | Ngan H.Y.S.,University of Hong Kong | Wong A.S.T.,University of Hong Kong
Oncogene | Year: 2011

Ovarian cancer is highly metastatic with a poor prognosis. The serine/threonine kinase, p70 S6 kinase (p70 S6K), which is a downstream effector of phosphatidylinositol 3-kinase/Akt pathway, is frequently activated in ovarian cancer. Here, we show that p70 S6K is a critical regulator of the actin cytoskeleton in the acquisition of the metastatic phenotype. This regulation is through two important activities: p70 S6K acts as an actin filament cross-linking protein and as a Rho family GTPase-activating protein. Ectopic expression of constitutively active p70 S6K in ovarian cancer cells induced a marked reorganization of the actin cytoskeleton and promoted directional cell migration. Using cosedimentation and differential sedimentation assays, p70 S6K was found to directly bind to and cross-link actin filaments. Immunofluorescence studies showed p70 S6K colocalized with cytochalasin D-sensitive actin at the leading edge of motile cells. The p70 S6K did not affect the kinetics of spontaneous actin polymerization, but could stabilize actin filaments by the inhibition of cofilin-induced actin depolymerization. In addition, we showed that p70 S6K stimulated the rapid activation of both Rac1 and Cdc42, and their downstream effector p21-activated kinase (PAK1), but not RhoA. Depletion of p70 S6K expression or inhibition of its activity resulted in significant inhibition of actin cytoskeleton reorganization and reduced migration, with a concomitant reduction in Rac1, Cdc42 and PAK1 activation, confirming that the effect was p70 S6K specific. Similarly, the actin cytoskeleton reorganization/migratory phenotype could be reversed by expression of dominant negative Rac1 and Cdc42, or inhibition of PAK1. These results reveal a new direction for understanding the oncogenic roles of p70 S6K in tumor progression. © 2011 Macmillan Publishers Limited All rights reserved.

Yu K.,University of Hong Kong | Zhang T.,University of Hong Kong
PLoS ONE | Year: 2012

The present study applied both metagenomic and metatranscriptomic approaches to characterize microbial structure and gene expression of an activated sludge community from a municipal wastewater treatment plant in Hong Kong. DNA and cDNA were sequenced by Illumina Hi-seq2000 at a depth of 2.4 Gbp. Taxonomic analysis by MG-RAST showed bacteria were dominant in both DNA and cDNA datasets. The taxonomic profile obtained by BLAST against SILVA SSUref database and annotation by MEGAN showed that activated sludge was dominated by Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Verrucomicrobia phyla in both DNA and cDNA datasets. Global gene expression annotation based on KEGG metabolism pathway displayed slight disagreement between the DNA and cDNA datasets. Further gene expression annotation focusing on nitrogen removal revealed that denitrification-related genes sequences dominated in both DNA and cDNA datasets, while nitrifying genes were also expressed in relative high levels. Specially, ammonia monooxygenase and hydroxylamine oxidase demonstrated the high cDNA/DNA ratios in the present study, indicating strong nitrification activity. Enzyme subunits gene sequences annotation discovered that subunits of ammonia monooxygenase (amoA, amoB, amoC) and hydroxylamine oxygenase had higher expression levels compared with subunits of the other enzymes genes. Taxonomic profiles of selected enzymes (ammonia monooxygenase and hydroxylamine oxygenase) showed that ammonia-oxidizing bacteria present mainly belonged to Nitrosomonas and Nitrosospira species and no ammonia-oxidizing Archaea sequences were detected in both DNA and cDNA datasets. © 2012 Yu, Zhang.

Wang A.Y.-M.,University of Hong Kong
Seminars in Dialysis | Year: 2012

Dialysis patients suffer a greatly heightened risk of cardiovascular morbidity and mortality. These patients also experience an extremely high prevalence of left ventricular hypertrophy, heart failure, and coronary artery disease. Thus, there is a clinical need to identify circulating biomarkers that have diagnostic value for cardiovascular disease and have prognostic importance so to facilitate earlier and more aggressive intervention. The natriuretic peptides, namely brain natriuretic peptide (BNP) or N-terminal pro-brain natriuretic peptide (NT-pro-BNP), belong to a family of vasopeptide hormones that are released from the heart and play a major role in blood pressure regulation and volume homeostasis through their direct effects on the kidney and systemic vasculature and represent a favorable aspect of neurohumoral activation. Testing for BNP or NT-pro-BNP has recently emerged as important diagnostic tool for heart failure and a useful biomarker for risk stratification in the general population. In dialysis patients, there has been interest in evaluating the potential of BNP and NT-pro-BNP as markers of volume status as they are frequently elevated in dialysis patients. However, the interpretation of their levels is confounded by impaired renal clearance and preexisting LV abnormalities which have limited their applicability as a surrogate marker of volume status. In this article, we discuss the pathophysiology accounting for the elevation of natriuretic peptides in dialysis patients and review current evidence that supports their clinical utility as a diagnostic and prognostic tool in this population. © 2012 Wiley Periodicals, Inc.

Lee C.K.,University of Hong Kong | Lam H.N.,University of Hong Kong
Energy | Year: 2013

A simplified three-dimensional finite difference model for a single (cylindrical energy pile) CEPwas developed. The present model was first verified with an analytical solution based on the special case that the material inside and outside the CEP had the same thermal properties. For the case of different thermal properties in the various ground regions, the calculated thermal resistance of the CEP (Rep) under a constant applied load was compared with the one determined with the assumption of a steady state inside the CEP. In both situations, the differences were found to be small. The effect of the thermal properties of various regions on the performance of the CEP was investigated. It was found the material underneath the CEP had negligible impact on the CEP performance. The soil material outside the CEP had stronger effect on the fluid temperature leaving the CEP (Tf, out) while Rep depended more on the material inside the CEP. Meanwhile, Rep reached a higher value at the beginning of each load cycle. The influence became significant for intermittent loading of the CEP. Furthermore, it was found that for optimal design involving a single pipe circuit inside the CEP, all pipes should be equally-spaced and connected consecutively. © 2013 Elsevier Ltd.

Teo K.C.,University of Hong Kong | Ho S.-L.,University of Hong Kong
Translational Neurodegeneration | Year: 2013

There is a substantial amount of evidence from experimental parkinsonian models to show the neuroprotective effects of monoamine oxidase-B (MAOB) inhibitors. They have been studied for their potential disease-modifying effects in Parkinson's disease (PD) for over 20 years in various clinical trials. This review provides a summary of the clinical trials and discusses the implications of their results in the context of disease-modification in PD. Earlier clinical trials on selegiline were confounded by symptomatic effects of this drug. Later clinical trials on rasagiline using delayed-start design provide newer insights in disease-modification in PD but success in achieving the aims of this strategy remain elusive due to obstacles, some of which may be insurmountable. © 2013 Teo and Ho; licensee BioMed Central Ltd.

Du Y.,University of Hong Kong | Yip H.,University of Hong Kong
Differentiation | Year: 2010

Bone morphogenetic proteins (BMPs) are secretory signal molecules that have a variety of regulatory functions during embryonic morphogenesis. BMP2 has been shown to induce differentiation in many cell types, mediated through the activation of its target genes: the inhibitors of differentiation (Id1-3) and key transcription factors. In this study, we investigated the effects of BMP2 on mouse neuroblastoma (Neuro2a) cell differentiation and regulation of the expression of Id1-3 and neural-specific transcription factors. Our results showed that BMP2 stimulation upregulated Id1-3 expression at the early stage of application by involvement of the Smad signaling pathway. BMP2 caused phosphorylation of Smad1/5/8 followed by upregulation of Id1-3. Co-incubation with Noggin, a BMP antagonist, or Smad1 siRNA transfection significantly inhibited phosphorylation of Smad1/5/8 and upregulation of Id protein. Furthermore, our results showed that BMP2-induced differentiation of Neuro2a cells into neurons by downregulating the expression of Id1-3 proteins and upregulating the expression of neural-specific transcriptional factors Dlx2, Brn3a, and NeuroD6. The results suggested that the transient upregulation of Id1-3 expression during the early phase of BMP stimulation may play a role in lineage specification and promote differentiation of neuroblastoma cells towards a neuronal phenotype. Subsequently, a coordinated increase in expression of proneural transcription factors and a decrease in Id1-3 expression may culminate in the transition from proliferation to neurogenesis and the terminal neuronal differentiation of neuroblastoma cells. © 2009 International Society of Differentiation.

Cheuk D.K.,University of Hong Kong
Cochrane database of systematic reviews (Online) | Year: 2010

BACKGROUND: Tumor lysis syndrome (TLS) is a serious complication of malignancies and can result in renal failure or death. Preliminary reports suggest that urate oxidase is highly effective in reducing serum uric acid. It is uncertain whether high quality evidence exists to support its routine use in children with malignancies. OBJECTIVES: We aimed to determine the effectiveness and safety of urate oxidase in the prevention and treatment of TLS in children with malignancies. SEARCH STRATEGY: We performed a comprehensive search of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library issue 2, 2009), MEDLINE (1966 to 2009), EMBASE (1980 to 2009) and CINAHL (1982 to 2009). SELECTION CRITERIA: Randomized controlled trials (RCT) and controlled clinical trials (CCT) evaluating urate oxidase for the prevention or treatment of TLS in children under 18 years with any malignancy. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted trial data and assessed individual trial quality. We used relative risk (RR) for binary data and mean difference (MD) for continuous data. MAIN RESULTS: We included five trials, involved 336 patients in the treatment groups and 458 patients in the control groups. One RCT and three CCTs compared urate oxidase and allopurinol. Two trials tested Uricozyme and two tested rasburicase for the prevention of TLS. The RCT showed no significant difference in mortality or renal failure between the treatment and the control groups. The frequency of normalization of uric acid (RR 19.09, 95% CI 1.28 to 285.41) and area under curve of uric acid (MD -201, 95% CI to -258.05 to -143.95) were significantly better in the treatment group. One patient developed hemolysis. One CCT reported significantly lower mortality due to TLS (RR 0.05, 95% CI 0.00 to 0.89) and lower incidence of renal failure (RR 0.13, 95% CI 0.05 to 0.35) in the treatment group. Another CCT found significantly lower uric acid in the treatment group at 72 hours (MD -98.33, 95% CI -170.66 to -26) and 168 hours (MD -103.67, 95% CI -179.00 to -28.34). All included trials are highly susceptible to biases.Another included RCT with 30 patients compared different doses of rasburicase (0.2 mg/kg versus 0.15 mg/kg), which demonstrated similar efficacy in the reduction of uric acid. Adverse events occurred in 20% of patients, including hemolysis, hypersensitivity and anemia. AUTHORS' CONCLUSIONS: Although urate oxidase might be effective in reducing serum uric acid, it is still unclear whether this translates into a reduction in mortality or renal failure. Clinicians should weigh the potential benefits of reducing uric acid and uncertain benefits of preventing renal failure or mortality from TLS against the potential risk of adverse effects.

Zhong W.,City University of Hong Kong | Lee C.K.,Hong Kong Polytechnic University | Ron Hui S.Y.,University of Hong Kong | Ron Hui S.Y.,Imperial College London
IEEE Transactions on Industrial Electronics | Year: 2013

In this paper, we present a brief overview of historical developments of wireless power and an analysis on the use of Tesla's resonators in domino forms for wireless power transfer. Relay resonators are spaced between the transmitter and receiver coils with the objectives of maximizing energy efficiency and increasing the overall transmission distance between the power source and the load. Analytical expressions for the optimal load and maximum efficiency at resonance frequency are derived. These equations are verified with practical measurements obtained from both coaxial and noncoaxial domino resonator systems. To avoid the use of high operating frequency for wireless power transfer in previous related research, the technique presented here can be used at submegahertz operation so as to minimize the power loss in both the power supply and the output stage. We demonstrated both theoretically and practically that unequal spacing for the coaxial straight domino systems has better efficiency performance than the equal-spacing method. Also, the flexibility of using resonators in various domino forms is demonstrated. © 2012 IEEE.

Chung T.N.H.,University of Hong Kong | Liu C.-H.,University of Hong Kong
Boundary-Layer Meteorology | Year: 2013

Flow resistance, ventilation, and pollutant removal for idealized two-dimensional (2D) street canyons of different building-height to street-width (aspect) ratios AR are examined using the friction factor f, air exchange rate (ACH), and pollutant exchange rate (PCH), respectively, calculated by large-eddy simulation (LES). The flows are basically classified into three characteristic regimes, namely isolated roughness, wake interference, and skimming flow, as functions of the aspect ratios. The LES results are validated by various experimental and numerical datasets available in the literature. The friction factor increases with decreasing aspect ratio and reaches a peak at AR = 0.1 in the isolated roughness regime and decreases thereafter. As with the friction factor, the ACH increases with decreasing aspect ratio in the wake interference and skimming flow regimes, signifying the improved aged air removal for a wider street canyon. The PCH exhibits a behaviour different from its ACH counterpart in the range of aspect ratios tested. Pollutants are most effectively removed from the street canyon with AR = 0.5. However, a minimum of PCH is found nearby at AR = 0.3, at which the pollutant removal is sharply weakened. Besides, the ACH and PCH are partitioned into the mean and turbulent components to compare their relative contributions. In line with our earlier Reynolds-averaged Navier-Stokes calculations (Liu et al., Atmos Environ 45:4763-4769, 2011), the current LES shows that the turbulent components contribute more to both ACH and PCH, consistently demonstrating the importance of atmospheric turbulence in the ventilation and pollutant removal for urban areas. © 2013 Springer Science+Business Media Dordrecht.

Cheung W.Y.,University of Hong Kong | Luk K.D.K.,University of Hong Kong
European Spine Journal | Year: 2013

Introduction Tuberculosis of the spine is a still a common disease entity, not only in developing countries but is also returning in developed countries especially in the immunecompromised patients. Conservative treatment with chemotherapy is still the main stay of treatment. This article focuses on the clinical and radiological outcomes, and problems with conservative treatment. Method The available literature of anti-tuberculosis chemotherapy in managing spinal tuberculosis was reviewed. Data sources included relevant literature of the English language identified through Medline search from 1946 to 2011. Personal experience and unpublished reviews from the authors' institution were also included. Results Although majority of patients respond well to anti-tuberculosis chemotherapy, about 15 % of them develop paradoxical response. The Medical Research Council (MRC) studies have shown that for patients without significant neurological deficits, operative and conservative treatment could produce the same clinical outcome at 15 years follow-up. Patients treated operatively with debridement and spinal fusion with strut graft had faster bony fusion and less kyphotic deformity. In contrast, those treated with drugs alone or with simple debridement without fusion may result in disease reactivation, severe kyphosis or late instability, which in turn may lead to lateonset Pott's paraplegia, back pain, sagittal imbalance and compromised pulmonary function that are difficult or risky to treat. Conclusion Recognition of the clinical and radiologic features of these late sequels is important for the management. Prevention of deformity in the early disease has been added to the modern standard of treatment of TB spine. © Springer-Verlag 2012.

Mak K.C.,University of Hong Kong | Cheung K.M.C.,University of Hong Kong
European Spine Journal | Year: 2013

Introduction Spinal tuberculosis represents a challenging disease to treat, not because of the technical expertise or the time required to cure it, but more so because of the decisions involved to treat it. The Medical Research Council (MRC) Working Party on Tuberculosis of the Spine designed trials to help address several questions. Methods A comprehensive literature search was performed using PubMed Medline, including English articles from 1934 to 1012, which pertain to spinal tuberculosis, with special effort in tracing the 13 MRC reports. The primary focus was on disease eradication, fusion rate, and a secondary focus on both short and long-term results in terms of disease recurrence and alignment. Additional searches were made on the use of spinal implants for infection cases. Results After reviewing MRC and non-MRC reports, it was evident that the "Hong Kong operation", which involved radical debridement and strut grafting the lesion, produced better short-, medium- And long-term results in such aspects as fusion rate, spinal deformity and relapse of abscess/sinus. Subsequent work by others demonstrated the importance of prevention of progressive kyphosis, therefore the need to identify risk factors for these and preemptive measures such as kyphosis correction, careful graft selection, and instrumentation. Conclusion Improvement in quality of life is also accompanied by higher patient expectations. Though developing nations may lack the resources now, eventually patients will demand better functional and cosmetic results after being afflicted by this disfiguring and potentially disabling disease, and the "Hong Kong operation" represented the best outcome, provided resources were available. © Springer-Verlag 2012.

Wang L.,Harbin Engineering University | Wang Q.,Harbin Engineering University | Wang Q.,University of Hong Kong
IEEE Geoscience and Remote Sensing Letters | Year: 2013

Subpixel mapping (SPM) is a promising technique to increase the spatial resolution of land cover maps. Markov random field (MRF)-based SPM has the advantages of considering spatial and spectral constraints simultaneously. In the conventional MRF, only the spectral information of one observed coarse spatial resolution image is utilized, which limits the SPM accuracy. In this letter, supplementary information from subpixel shifted remote sensing images (SSRSI) is used with MRF to produce more accurate SPM results. That is, spectral information from SSRSI is incorporated into the likelihood energy function of MRF to provide multiple spectral constraints. Simulated and real images were tested with the subpixel/pixel spatial attraction model, Hopfield neural networks (HNNs), HNN with SSRSI, image interpolation then hard classification, conventional MRF, and proposed MRF with SSRSI based SPM methods. Results showed that the proposed method can generate the most accurate SPM results among these methods. © 2004-2012 IEEE.

Huang Y.,University of Hong Kong | Young B.,University of Hong Kong
Thin-Walled Structures | Year: 2013

Experimental and numerical investigation of cold-formed lean duplex stainless steel flexural members is presented in this paper. The test specimens were cold-rolled from flat plates of lean duplex stainless steel with the nominal 0.2% proof stress of 450 MPa. Specimens of square and rectangular hollow sections subjected to both major and minor axes bending were tested. A finite element model has been created and verified against the test results using the material properties obtained from coupon tests. It is shown that the model can accurately predict the behaviour of lean duplex stainless steel flexural members. An extensive parametric study was carried out using the verified finite element model. The test and numerical results as well as the available data on lean duplex beams are compared with design strengths predicted by various existing design rules, such as the American Specification, Australian/New Zealand Standard, European Code and direct strength method for cold-formed stainless steel. Reliability analysis was performed to evaluate the reliability of the design rules. It is shown that these current design rules provide conservative predictions to the design strengths of lean duplex stainless steel flexural members. In this study, modified design rules on the American Specification, Australian/New Zealand Standard, European Code and direct strength method are proposed, which are shown to improve the accuracy of these design rules in a reliable manner. © 2013 Elsevier Ltd.

Sadjadi S.,University of Hong Kong | Zhang Y.,University of Hong Kong | Kwok S.,University of Hong Kong
Astrophysical Journal | Year: 2015

The 11.3 μm emission feature is a prominent member of the family of unidentified infrared emission (UIE) bands and is frequently attributed to out-of-plane bending modes of polycyclic aromatic hydrocarbon (PAH) molecules. We have performed quantum mechanical calculations of 60 neutral PAH molecules and found that it is difficult to reconcile the observed astronomical feature with any or a mix of these PAH molecules. We have further analyzed the fitting of spectra of several astronomical objects by the NASA PAH database program and found that reasonable fittings to the observed spectra are only possible by including significant contributions from oxygen-and/or magnesium-containing molecules in the mix. A mix of pure PAH molecules, even including units of different sizes, geometry, and charged states, is unable to fit the astronomical spectra. Preliminary theoretical results on the vibrational spectra of simple molecules with mixed aromatic/aliphatic structures show that these structures have consistent clusters of vibrational modes and could be viable carriers of the UIE bands. © 2015. The American Astronomical Society. All rights reserved.

The origin of the catalytic power of enzymes with a meta-stable native state, e.g. molten globular state, is an unsolved challenging issue in biochemistry. To help understand the possible differences between this special class of enzymes and the typical ones, we report here computer simulations of the catalysis of both the well-folded wild-type and the molten globular mutant of chorismate mutase. Using the ab initio quantum mechanical/molecular mechanical minimum free-energy path method, we determined the height of reaction barriers that are in good agreement with experimental measurements. Enzyme-substrate interactions were analyzed in detail to identify factors contributing to catalysis. Computed angular order parameters of backbone N-H bonds and side-chain methyl groups suggested site-specific, non-uniform rigidity changes of the enzymes during catalysis. The change of conformational entropy from the ground state to the transition state revealed distinctly contrasting entropy/enthalpy compensations in the dimeric wild-type enzyme and its molten globular monomeric variant. A unique catalytic strategy was suggested for enzymes that are natively molten globules: some may possess large conformational flexibility to provide strong electrostatic interactions to stabilize the transition state of the substrate and compensate for the entropy loss in the transition state. The equilibrium conformational dynamics in the reactant state were analyzed to quantify their contributions to the structural transitions enzymes needed to reach the transition states. The results suggest that large-scale conformational dynamics make important catalytic contributions to sampling conformational regions in favor of binding the transition state of substrate. © 2013 Science China Press and Springer-Verlag Berlin Heidelberg.

Rowell C.,ASTRI Hong Kong | Lam E.Y.,University of Hong Kong
IEEE Antennas and Propagation Magazine | Year: 2012

This paper is a survey of internal antennas in mobile phones from 1997 to 2010. It covers almost 60 GSM and 3G handsets, ranging from the first GSM handset with an internal antenna to the current Nokia, Sony-Ericsson, Motorola, and Apple handsets. The paper discusses different types of mobile-phone antennas, feeding structures, active antennas, isolation, and antenna loading techniques. This paper examines different design techniques for mobile-phone antennas, and the limitations of antenna design due to manufacturing technologies and the effect of handset materials. Antenna performance parameters, including S parameters, radiation efficiency, SAR, and TRP/TIS are reported for the surveyed handsets. The effective antenna volume for every antenna is calculated, in order to determine the average volume/space required for each antenna type and the corresponding performance. Some of the handsets are further simulated using commercial electromagnetic simulators to illustrate the electromagnetic-field distributions. This paper summarizes the antenna design parameters as a function of handset performance, and presents a short summary of design procedure. © 2011 IEEE.

Leung F.,University of Hong Kong
Journal of orthopaedic surgery (Hong Kong) | Year: 2012

To assess the one-year outcome of a dynamic hip screw (DHS) blade in the treatment of AO/OTA 31-A1 and 31-A2 intertrochanteric hip fractures. 35 men and 65 women aged 47 to 100 (mean, 83) years underwent fixation with a DHS blade for A1 (n=47) and A2 (n=53) intertrochanteric hip fractures after a low-energy injury. Patients were operated on within 48 hours of admission. Anteroposterior and lateral radiographs were examined for the tip-apex distance and femoral shortening. Potential complications were looked for, including implant migration, cut-out, loosening, or breakage. Functional outcome was based on the Parker mobility score. The 30-day and one-year mortality rates were 5% and 20%, respectively. At the one-year follow-up, 81 patients were available, and all fractures had healed without varus deformity. The mean tip-apex distance was 14.1 (range, 5.7-31.1; SD, 4.3) mm. The mean femoral shortening was 4.9 (range, 0-20.2; SD, 4.8) mm. The mean Parker score decreased to 3.8 at one-year follow-up from 5.9 before injury (p<0.001). There was one loss of fixation secondary to a non-traumatic subcapital fracture at 3 months, for which a bipolar hemiarthroplasty was performed. CONCLUSION; The DHS blade system is effective in treating AO/OTA 31-A1 and 31-A2 intertrochanteric hip fractures and results in a low complication rate.

Zhao Y.X.,University of Hong Kong | Wang Z.D.,University of Hong Kong
Physical Review Letters | Year: 2015

We develop a topological theory for disordered Weyl semimetals in the framework of the gauge invariance of the replica formalism and boundary-bulk correspondence of Chern insulators. An anisotropic topological θ term is analytically derived for the effective nonlinear σ model. It is this nontrivial topological term that ensures that the bulk transverse transport of Weyl semimetals is robust against disorders. Moreover, we establish a general diagram that reveals the intrinsic relations among topological terms in the nonlinear σ models and gauge response theories, respectively, for (2n+2)-dimensional topological insulators, (2n+1)-dimensional chiral fermions, (2n+1)-dimensional chiral semimetals, and (2n)-dimensional topological insulators with n being a positive integer. © 2015 American Physical Society.

Xu J.,University of Hong Kong | Zhang C.,University of Hong Kong | Wong K.K.Y.,University of Hong Kong | Tsia K.K.,University of Hong Kong
Optics Letters | Year: 2014

We demonstrate all-optical ultrahigh-speed swept-source optical coherence tomography (OCT) based on amplified optical time-stretch (AOT). Such an inertia-free wavelength-swept mechanism, via group velocity dispersion, enables us to realize OCT with an A-scan rate well above MHz. More importantly, the key significance of AOT-OCT is its simultaneous broadband Raman amplification during the time-stretch process-greatly enhancing the detection sensitivity compared with prior attempts to apply optical time-stretch to OCT. Here, we report on an AOT-OCT system which is operated at an A-scan rate of 7.14 MHz, a superior roll-off performance (>2 mm?dB), a record-high sensitivity of time-stretch-based OCT (>80 dB) with a broadband gain bandwidth of 80 nm, which results in an axial resolution of ∼15 μm. Our AOT-OCT system is thus able to, for the first time to the best of our knowledge, perform time-stretch-based OCT of biological tissue in vivo. It represents a major step forward in utilizing AOT as an alternative for achieving practical MHz OCT, without any long-term mechanical stability concerns as in typical sweptsource OCT or bypassing the speed limitation of the image sensor employed in spectral-domain OCT. © 2014 Optical Society of America.

Ng F.Y.,University of Hong Kong
Journal of orthopaedic surgery (Hong Kong) | Year: 2012

To compare total knee arthroplasty (TKA) patients who received continuous femoral nerve block (FNB) with local anaesthetics through a catheter versus patient-controlled analgesia (PCA) with intravenous morphine. 50 women and 10 men aged 51 to 84 years with matched characteristics underwent TKA and received either continuous FNB with local anaesthetics through a catheter (n=30) or PCA with intravenous morphine (n=30). None of the patients had had previous knee surgery. All operations were performed according to the standard protocol. Daily mean pain numerical rating scale at rest (NRS-R) and during movement (NRS-M), requirement of extra pain control, complications related to pain control, and overall patient satisfaction in both groups were compared. Both groups were similar in terms of pain NRS-R and NRS-M, overall satisfaction, and length of hospital stay. Within each group, pain NRS-M score was significantly higher than pain NRS-R score. In the FNB group, 3 patients had dislodgement of the femoral catheter on day 1 and switched to PCA with intravenous morphine. Two of them had fair satisfaction. Patients in the PCA group had significantly more side-effects (nausea, vomiting, dizziness, and pruritis); 2 of the 5 patients with nausea and vomiting had fair satisfaction. No patients had any surgical complication. Both FNC and PCA provide reliable pain control.

Liao B.,University of Hong Kong | Chan S.C.,University of Hong Kong
IEEE Transactions on Antennas and Propagation | Year: 2012

A new method for direction finding with partly calibrated uniform linear arrays (ULAs) is presented. It is based on the conventional estimation of signal parameters via rotational invariance techniques (ESPRIT) by modeling the imperfections of the ULAs as gain and phase uncertainties. For a fully calibrated array, it reduces to the conventional ESPRIT algorithm. Moreover, the direction-of-arrivals (DOAs), unknown gains, and phases of the uncalibrated sensors can be estimated in closed form without performing a spectral search. Hence, it is computationally very attractive. The Cramér-Rao bounds (CRBs) of the partly calibrated ULAs are also given. Simulation results show that the root mean squared error (RMSE) performance of the proposed algorithm is better than the conventional methods when the number of uncalibrated sensors is large. It also achieves satisfactory performance even at low signal-to-noise ratios (SNRs). © 2011 IEEE.

Chan S.-C.,University of Hong Kong | Chu Y.,University of Hong Kong
IEEE Transactions on Audio, Speech and Language Processing | Year: 2012

The filtered-x LMS (FxLMS) algorithm has been widely used in active noise control (ANC) systems, where the secondary path is usually estimated online by injecting auxiliary noises. In such an ANC system, the ANC controller and the secondary-path estimator are coupled with each other, which make it difficult to analyze the performance of the entire system. Therefore, a comprehensive performance analysis of broadband ANC systems is not available currently to our best knowledge. In this paper, the convergence behavior of the FxLMS algorithm in broadband ANC systems with online secondary-path modeling is studied. Difference equations which describe the mean and mean square convergence behaviors of the adaptive algorithms are derived. Using these difference equations, the stability of the system is analyzed. Finally, the coupled equations at the steady state are solved to obtain the steady-state excess mean square errors (EMSEs) for the ANC controller and the secondary-path estimator. Computer simulations are conducted to verify the agreement between the simulated and theoretically predicted results. Moreover, using the proposed theoretical analysis, a systematic and simple design procedure for ANC systems is proposed. The usefulness of the theoretical results and design procedure is demonstrated by means of a design example. © 2012 IEEE.

Observational studies usually show that moderate alcohol use is associated with better cognitive function. Such studies are vulnerable to residual confounding arising from systematic differences between moderate alcohol users and others. A Mendelian randomization study carried out in a suitable population, such as southern Chinese men, in which alcohol use is low to moderate and is influenced by genotype, offers an alternative and superior approach for clarifying the causal effect of moderate alcohol use on cognitive function. The authors used aldehyde dehydrogenase 2 (ALDH2) genotype (AA, GA, or GG) as an instrumental variable in 2-stage least squares analysis to obtain unbiased estimates of the relation of alcohol consumption (measured in alcohol units (10 g ethanol) per day) with cognitive function, assessed from delayed 10-word recall score (n = 4,707) and Mini-Mental State Examination (MMSE) score (n = 2,284), among men from the Guangzhou Biobank Cohort Study (2003-2008). ALHD2 genotype was strongly associated with alcohol consumption, with an F statistic of 71.0 in 2-stage least squares analysis. Alcohol consumption was not associated with delayed 10-word recall score (-0.03 words per alcohol unit, 95% confidence interval:-0.18, 0.13) or MMSE score (0.06 points per alcohol unit, 95% confidence interval:-0.22, 0.34). Moderate alcohol use is unlikely to be cognitively protective. © The Author 2012. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved.

Fan J.,University of Hong Kong | Wang L.,University of Hong Kong
Journal of Heat Transfer | Year: 2011

Nanofluids-fluid suspensions of nanometer-sized particles-are a very important area of emerging technology and are playing an increasingly important role in the continuing advances of nanotechnology and biotechnology worldwide. They have enormously exciting potential applications and may revolutionize the field of heat transfer. This review is on the advances in our understanding of heat-conduction process in nanofluids. The emphasis centers on the thermal conductivity of nanofluids: its experimental data, proposed mechanisms responsible for its enhancement, and its predicting models. A relatively intensified effort has been made on determining thermal conductivity of nanofluids from experiments. While the detailed microstructure-conductivity relationship is still unknown, the data from these experiments have enabled some trends to be identified. Suggested microscopic reasons for the experimental finding of significant conductivity enhancement include the nanoparticle Brownian motion, the Brownian-motion-induced convection, the liquid layering at the liquid-particle interface, and the nanoparticle cluster/aggregate. Although there is a lack of agreement regarding the role of the first three effects, the last effect is generally accepted to be responsible for the reported conductivity enhancement. The available models of predicting conductivity of nanofluids all involve some empirical parameters that negate their predicting ability and application. The recently developed first-principles theory of thermal waves offers not only a macroscopic reason for experimental observations but also a model governing the microstructure-conductivity relationship without involving any empirical parameter. © 2011 American Society of Mechanical Engineers.

Liao B.,University of Hong Kong | Chan S.-C.,University of Hong Kong
IEEE Antennas and Wireless Propagation Letters | Year: 2012

This letter proposes a new adaptive beamforming algorithm for uniform linear arrays (ULAs) with unknown mutual coupling. It is based on the fact that the mutual coupling matrix (MCM) of a ULA can be approximated as a banded symmetric Toeplitz matrix as the mutual coupling between two sensor elements is inversely related to their separation, and hence it is negligible when they are separated by a few wavelengths. Taking advantage of this specific structure of the MCM, a new approach to calibrate the signal steering vector is proposed. By incorporating this improved steering vector estimate with a diagonally loaded robust beamformer, a new adaptive beamformer for ULA with unknown mutual coupling is obtained. Simulation results show that the proposed steering vector estimate considerably improves the robustness of the beamformer in the presence of unknown mutual coupling. Moreover, with appropriate diagonal loading, it is found that the proposed beamformer can achieve nearly optimal performance at all signal-to-noise ratio (SNR) levels. © 2002-2011 IEEE.

Su R.K.L.,University of Hong Kong | Wang L.,University of Hong Kong
Engineering Structures | Year: 2012

Steel jacketing has been widely used for strengthening reinforced concrete (RC) columns. Previous experimental studies have evaluated the ductility and shear performance of steel jacketed columns. However, in practice, the RC columns to be strengthened are usually subjected to pre-compressed axial loads. The stress-lagging effect between the original column and the new jacket due to the pre-existing load has not been addressed previously. In this paper, a simple and innovative decompression approach, using precambered steel plates, is proposed to upgrade the axial capacity of preloaded RC columns. An experimental study was conducted to validate the effectiveness of this approach for increasing the axial load capacity of RC columns. A theoretical model was also developed to predict the axial load capacity of the plate-strengthened columns. Comparison of theoretical and experimental results showed that the theoretical model accurately predicted the axial load-carrying capacities of the plate-strengthened columns. © 2012 Elsevier Ltd.

Huang Y.,University of Hong Kong | Young B.,University of Hong Kong
Thin-Walled Structures | Year: 2012

This paper presents the behaviour of cold-formed lean duplex stainless steel for six different sections, among which two are square hollow sections and four are rectangular hollow sections. The test specimens were cold-rolled from flat strips of lean duplex stainless steel. The material properties of high strength cold-formed lean duplex stainless steel square and rectangular hollow sections were determined. Tensile coupons in the flat portions and corners of each section were tested. Hence, the Youngs moduli, 0.2% proof stresses, 1.0% proof stresses, tensile strengths, elongation at fracture and the RambergOsgood parameter (n) of lean duplex material for each section were measured. The material properties of the complete cross-sections in the cold-worked state were also obtained from stub column tests. The initial local geometric imperfections of the six sections were measured, and the profiles of the local imperfections along cross-section were plotted for each section. Residual stresses were measured for section 150×50×2.5 using the method of sectioning. The membrane and bending residual stress distributions in the cross-section were obtained and plotted. Furthermore, finite element model of stub columns was developed and compared well with the test results. The stub column test strengths were also compared with the design strengths predicted by the American Specification, Australian/New Zealand Standard and European Code for stainless steel structures. Generally, the three specifications conservatively predicted the column strengths. The European Code provides the most conservative prediction. © 2012 Elsevier Ltd.

Yeo S.I.,University of Hong Kong
International journal of rheumatic diseases | Year: 2013

Gout is a common condition which is mainly treated with the hypo-uricemic agent, allopurinol. Although allopurinol is generally a well-tolerated drug, there is a small risk of developing potentially fatal complications, such as allopurinol hypersensitivity syndrome. Recent advances in pharmacogenomics have made possible the identification of genes which confer susceptibility to specific drugs. A recent multi-national case-control study has reported allopurinol as the most common drug associated with Stevens-Johnson syndrome and toxic epidermal necrolysis. Several studies have established a strong association between the human leukocyte antigen (HLA)-B*5801 gene and development of Stevens-Johnson syndrome and toxic epidermal necrolysis. The allele frequency of HLA-B*5801 is highest in the South East Asian population.Since other hypo-uricemic agents are available, patients may wish to have HLA-B*5801 testing before being started on allopurinol. As the test for HLA-B*5801 is expensive, time-consuming and only available in selected laboratories, there is a need to evaluate the utility and cost-effectiveness of this test in our region. © 2013 The Author International Journal of Rheumatic Diseases © 2013 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd.

Yoon S.,University of Hong Kong | Lam T.-H.,University of Hong Kong
BMC Public Health | Year: 2013

Background: Corporate social responsibility (CSR) has become an integral element of how the alcohol industry promotes itself. The existing analyses of CSR in the alcohol industry point to the misleading nature of these CSR practices. Yet, research has been relatively sparse on how the alcohol industry advances CSR in an attempt to facilitate underlying business interests, and in what ways the ongoing display of industry CSR impacts public health. This paper aims to investigate the alcohol industry's recent CSR engagements and explain how CSR forms part of the industry's wider political and corporate strategies. Methods. Our study used qualitative methods to collect and analyse data. We searched for materials pertaining to CSR activities from websites of three transnational alcohol corporations, social media platforms, media reports and other sources. Relevant documents were thematically analysed with an iterative approach. Results: Our analysis identified three CSR tactics employed by the alcohol companies which are closely tied in with the industry's underlying corporate intents. First, the alcohol manufacturers employ CSR as a means to frame issues, define problems and guide policy debates. In doing this, the alcohol companies are able to deflect and shift the blame from those who manufacture and promote alcoholic products to those who consume them. Second, the alcohol corporations promote CSR initiatives on voluntary regulation in order to delay and offset alcohol control legislation. Third, the alcohol corporations undertake philanthropic sponsorships as a means of indirect brand marketing as well as gaining preferential access to emerging alcohol markets. Conclusions: The increasing penetration and involvement of the alcohol industry into CSR highlights the urgent needs for public health counter actions. Implementation of any alcohol control measures should include banning or restricting the publicity efforts of the industry's CSR and informing the public of the alcohol industry's notion of social responsibility. More significantly, an internationally binding instrument should be called for to enable countries to differentiate between genuine concerns and spurious altruism, and in doing so, resist the industry's attempt to erode alcohol control. © 2013 Yoon and Lam; licensee BioMed Central Ltd.

Yue Z.Q.,University of Hong Kong
Poromechanics V - Proceedings of the 5th Biot Conference on Poromechanics | Year: 2013

This paper presents a hypothesis of compressed methane gas expansion and migration in crustal rocks and faults for the cause of earthquakes. An earth quaking is an adiabatic process of kinetic interaction between rapid upward expansion and migration of compressed natural gas and its surrounding crustal rocks and ground soils. The natural gas is produced in core and/or mantle. It is escaped from its traps in deep fault zones of the lower crustal rocks. The interaction is instantaneous and flashing. It can be complete within few to tens and to hundreds seconds. The gas expansion and migration are confined and constrained by the inward gravity, the tectonic stresses, and the rigidness and strengths of the crustal rocks. The kinetic energy of earth quaking is mainly the physical expansion energy of the highly compressed methane gas. The gas expansion work causing the 2008 Wenchuan Earthquake and the 2011 Off the Pacific Coast of Tohoku Earthquake are estimated. © 2013 American Society of Civil Engineers.

Li M.-X.,University of Hong Kong | Gui H.-S.,University of Hong Kong | Kwan J.S.H.,University of Hong Kong | Bao S.-Y.,University of Hong Kong | Sham P.C.,University of Hong Kong
Nucleic Acids Research | Year: 2012

Exome sequencing strategy is promising for finding novel mutations of human monogenic disorders. However, pinpointing the casual mutation in a small number of samples is still a big challenge. Here, we propose a three-level filtration and prioritization framework to identify the casual mutation(s) in exome sequencing studies. This efficient and comprehensive framework successfully narrowed down whole exome variants to very small numbers of candidate variants in the proof-of-concept examples. The proposed framework, implemented in a user-friendly software package, named KGGSeq (http://statgenpro.psychiatry.hku. hk/kggseq), will play a very useful role in exome sequencing-based discovery of human Mendelian disease genes. © 2011 The Author(s).

Li Y.,University of Hong Kong
Science and Engineering Ethics | Year: 2013

Text-based plagiarism, or copying language from sources, has recently become an issue of growing concern in scientific publishing. Use of CrossCheck (a computational text-matching tool) by journals has sometimes exposed an unexpected amount of textual similarity between submissions and databases of scholarly literature. In this paper I provide an overview of the relevant literature, to examine how journal gatekeepers perceive textual appropriation, and how automated plagiarism-screening tools have been developed to detect text matching, with the technique now available for self-check of manuscripts before submission; I also discuss issues around English as an additional language (EAL) authors and in particular EAL novices being the typical offenders of textual borrowing. The final section of the paper proposes a few educational directions to take in tackling text-based plagiarism, highlighting the roles of the publishing industry, senior authors and English for academic purposes professionals. © 2012 The Author(s).

Lo S.H.,University of Hong Kong
Finite Elements in Analysis and Design | Year: 2014

In view of the simplicity and the linearity of regular grid insertion, a multi-grid insertion scheme is proposed for the three-dimensional Delaunay triangulation of non-uniform point distributions by recursive application of the regular grid insertion to an arbitrary subset of the original point set. The fundamentals and difficulties of three-dimensional Delaunay triangulation of highly non-uniformly distributed points by the insertion method are reviewed. Current strategies and methods of point insertions for non-uniformly distributed spatial points are discussed. An enhanced kd-tree insertion algorithm with a specified number of points in a cell and its natural sequence derived from a sandwich insertion scheme is also presented. The regular grid insertion, the enhanced kd-tree insertion and the multi-grid insertion have been rigorously studied with benchmark non-uniform distributions of 0.4-20 million points. It is found that the kd-tree insertion is more efficient in locating the base tetrahedron, but it is also more sensitive to the triangulation of non-uniform point distributions with a large amount of conflicting elongated tetrahedra. Including the grid construction time, multi-grid insertion is the most stable and efficient for all the uniform and non-uniform point distributions tested. © 2014 Elsevier B.V.

Sharr W.W.,University of Hong Kong
Transplantation | Year: 2014

Liver transplantation (LT) is a well-established option of cure for hepatocellular carcinoma (HCC). Milan criteria is recognized as standard for selection of patients and set the baseline of survival to be achieved. It has been shown that tumor biology including differentiation, vascular invasion, and serum α-fetoprotein (AFP) predict posttransplant recurrence and survival better than morphology. Downstaging by locoregional therapies of HCC before LT, with the response to treatments and progression within observation period, serves as a selection tool rather than modulation of tumor biology. It selects those patients outside standard criteria at presentation but good tumor biology and high chance of good outcome to receive transplantation. The definition of downstaging should be differentiated from neo-adjuvant therapy, and the objectives in surgical and pretransplant candidates also differ.Published studies in this area showed variation in inclusion criteria, downstaging protocol and assessment of successful downstaging. Tumor biology predownstaging and postdownstaging was not incorporated. Posttransplant outcome were not clearly stated with regard to intention-to-treat survival, disease-free survival, and comparison against those originally within criteria. Meta-analysis of these results was impossible. Nevertheless, majority had reasonable protocol and were able to select patients whom likely to have good outcome. At present, there is no evidence that downstaged patients have a poorer prognosis than those presenting within the Milan criteria. Patients with tumors outside Milan criteria should be offered downstaging therapies. Those who are successfully downstaged to within Milan criteria should be eligible to liver transplant as same as those initially fit the criteria. In the last decade, various extended criteria of HCC for LT have been proposed and reported satisfactory survival. That makes downstaging technically unnecessary.To refine and validate the role of downstaging, it needs collaborative and prospective study with significant sample size, adequate preoperative staging, standardized protocol of selection of patients, and approaches to downstaging. Selection criteria should include histopathological data on tumor biology and serum AFP. There should be standardized definition of successful downstaging. Posttransplant disease-free survival should be reported in detail and compared with those who fit the standard criteria initially. A consistent immunosuppressant protocol is important to avoid bias.

Chan S.C.,University of Hong Kong
Transplantation | Year: 2014

Liver transplantation (LT) is the most effective treatment for small and unresectable hepatocellular carcinomas (HCCs). With scarcity of deceased donor livers, living donor LT (LDLT) is the alternative to deceased donor LT (DDLT). Animal studies have suggested that regeneration of the partial liver graft encourages HCC recurrence. Increased recurrence was observed in a few studies. Thus, there is the belief that the use of small-for-size graft carries the potential risk of disease recurrence. Nevertheless, those studies were retrospective, with sample sizes not large enough for conclusions.Living donor LT can be performed when a suitable donor is available. The fast tracking of patients for transplantation without a period of observation is an issue. Meta-analyses, however, showed no significant increase in HCC recurrence after LDLT. Patients listed for DDLT and without suitable living donors have to endure a long wait, during which the aggressiveness of their HCC is observed. Such observation almost guarantees slow disease progression when they get transplanted. Nevertheless, a long wait has the disadvantage of transplanting patients with more advanced tumors, although still within standard criteria. Judicious use of deceased donor grafts is the responsibility of the transplant community.Living donor LT for HCC should only be performed after careful assessment of the recipient and tumor status. Although tumor size and number are references widely adopted in tumor staging, biological staging of tumors using positron emission tomography could provide additional information of tumor behavior. A high level of serum α-fetoprotein also warns against LT because it is predictive of a high HCC recurrence rate.

Chesi G.,University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2014

This technical note addresses the design of robust static output feedback controllers that minimize a polynomial cost and robustly stabilize a system with polynomial dependence on an uncertain vector constrained in a semialgebraic set. The admissible controllers are those in a given hyper-rectangle for which the system is well-posed. First, the class of robust stabilizability functions is introduced, i.e., the functions of the controller that are positive whenever the controller robustly stabilizes the system. Second, the approximation of a robust stabilizability function with a controller-dependent lower bound is proposed through a sums-of-squares (SOS) program exploiting a technique developed in the estimation of the domain of attraction. Third, the derivation of a robust stabilizing controller from the found controller-dependent lower bound is addressed through a second SOS program that provides an upper bound of the optimal cost. The proposed method is asymptotically non-conservative under mild assumptions. © 1963-2012 IEEE.

Lee P.H.,University of Hong Kong | Lee P.H.,Hong Kong Polytechnic University
Journal of Epidemiology | Year: 2014

Background: When using the change-in-estimate criterion, a cutoff of 10% is commonly used to identify confounders. However, the appropriateness of this cutoff has never been evaluated. This study investigated cutoffs required under different conditions. Methods: Four simulations were performed to select cutoffs that achieved a significance level of 5% and a power of 80%, using linear regression and logistic regression. A total of 10 000 simulations were run to obtain the percentage differences of the 4 fitted regression coefficients (with and without adjustment). Results: In linear regression, larger effect size, larger sample size, and lower standard deviation of the error term led to a lower cutoff point at a 5% significance level. In contrast, larger effect size and a lower exposure-confounder correlation led to a lower cutoff point at 80% power. In logistic regression, a lower odds ratio and larger sample size led to a lower cutoff point at a 5% significance level, while a lower odds ratio, larger sample size, and lower exposure-confounder correlation yielded a lower cutoff point at 80% power. Conclusions: Cutoff points for the change-in-estimate criterion varied according to the effect size of the exposure-outcome relationship, sample size, standard deviation of the regression error, and exposure-confounder correlation. © 2013 Paul H. Lee.

Lee P.H.,University of Hong Kong
American Journal of Clinical Nutrition | Year: 2013

Background: Accelerometers are gaining popularity for the assessment of the physical activity level; however, compliance is a problem that results in missing data. Data from study days in which the accelerometer is not worn for a number of hours that are sufficient to reach a predetermined cutoff value are considered invalid and discarded. The problem of missing data is commonly handled by imputation; however, all traditional imputation methods ignore the available information from invalid days. Objective: In this study, I propose a new approach to the imputation of missing accelerometer data that takes into account the data available from invalid days. Design: A total of 4069 participants in NHANES waves 2003-2004 and 2005-2006 who provided 7 d of valid accelerometer data were used to illustrate this new approach. The method of imputation was a combined approach that combined the available data from valid days and invalid days to impute missing values. Simulation studies were carried out to compare this new combined approach with the traditional imputation method for 1) accuracy and 2) effect-size estimation of the sexphysical activity relation by using the root mean squared error (RMSE). Results: The combined approach performed significantly better than traditional imputation method (all t tests P<0..001), with the percentage reduction of the RMSE for accuracy and effect-size estimation that ranged from 12.4% to 17.3% and 19.8% to 32.9%, respectively. Conclusion: The combined approach significantly outperforms the traditional imputation algorithm. © 2013 American Society for Nutrition.

Li M.-X.,University of Hong Kong | Gui H.-S.,University of Hong Kong | Kwan J.S.H.,University of Hong Kong | Sham P.C.,University of Hong Kong
American Journal of Human Genetics | Year: 2011

The gene has been proposed as an attractive unit of analysis for association studies, but a simple yet valid, powerful, and sufficiently fast method of evaluating the statistical significance of all genes in large, genome-wide datasets has been lacking. Here we propose the use of an extended Simes test that integrates functional information and association evidence to combine the p values of the single nucleotide polymorphisms within a gene to obtain an overall p value for the association of the entire gene. Our computer simulations demonstrate that this test is more powerful than the SNP-based test, offers effective control of the type 1 error rate regardless of gene size and linkage-disequilibrium pattern among markers, and does not need permutation or simulation to evaluate empirical significance. Its statistical power in simulated data is at least comparable, and often superior, to that of several alternative gene-based tests. When applied to real genome-wide association study (GWAS) datasets on Crohn disease, the test detected more significant genes than SNP-based tests and alternative gene-based tests. The proposed test, implemented in an open-source package, has the potential to identify additional novel disease-susceptibility genes for complex diseases from large GWAS datasets. © 2011 The American Society of Human Genetics.

Lo C.M.,University of Hong Kong
Cell Death and Differentiation | Year: 2016

The mechanisms of how signaling pathways are coordinated and integrated for the maintenance of the self-renewal of human embryonic stem cells (hESCs) and the acquisition of pluripotency in reprogramming are still only partly understood. CDK1 is a key regulator of mitosis. Recently, CDK1 has been shown to be involved in regulating self-renewal of stem cells, even though the mechanistic role of how CDK1 regulates pluripotency is unknown. In this report, we aim to understand how CDK1 can control pluripotency by reducing CDK1 activity to a level that has no effect on cell cycle progression. We demonstrated that high levels of CDK1 is associated with the pluripotency stage of hESCs; and decreased CDK1 activity to a level without perturbing the cell cycle is sufficient to induce differentiation. CDK1 specifically targets the phosphorylation of PDK1 and consequently the activity of PI3K/Akt and its effectors ERK and GSK3β. Evidence of the reversion of inactive CDK1-mediated differentiation by the inhibition of Akt signaling effectors suggests that the CDK1-PDK1-PI3K/Akt kinase cascade is a functional signaling pathway for the pluripotency of hESCs. Moreover, cyclin B1-CDK1 complexes promote somatic reprogramming efficiency, probably by regulating the maturation of induced pluripotent stem cells (iPSCs), as cyclin B1 stimulates a higher cellular level of LIN28A, suggesting that monitoring iPSC factors could be a new path for the enhancement of reprogramming efficiency. Together, we demonstrate an essential role for the CDK1-PDK1-PI3K/Akt kinase signaling pathway in the regulation of self-renewal, differentiation, and somatic reprogramming, which provides a novel kinase cascade mechanism for pluripotency control and acquisition.Cell Death and Differentiation advance online publication, 16 September 2016; doi:10.1038/cdd.2016.84. © 2016 The Author(s)

Mok C.C.,Tuen Mun Hospital | Kwok R.C.L.,University of Hong Kong | Yip P.S.F.,University of Hong Kong
Arthritis and Rheumatism | Year: 2013

Objective To study the effect of renal disease on the standardized mortality ratio (SMR) and life expectancy of patients with systemic lupus erythematosus (SLE). Methods Patients whose diagnosis met ≥4 American College of Rheumatology criteria for SLE were longitudinally followed up from 1995 to 2011. The cumulative survival rate, SMR, and life expectancy were calculated, and the effect of renal involvement, histologic class of lupus nephritis, renal damage, and end-stage renal disease (ESRD) on these parameters was evaluated. Results Of the 694 SLE patients studied, 368 (53%) had renal disease, and the distribution of histologic classes (among 285 patients) was class I (1%), class II (6%), class III (19%), class IV (47%), class III/IV + class V (10%), and class V (16%). Renal damage was present in 79 patients (11%), and 24 (3%) developed ESRD. The age- and sex-adjusted hazard ratios (HRs) of mortality in SLE patients with renal disease, those with renal damage, and those with ESRD, as compared to those without, were 2.23 (95% confidence interval [95% CI] 1.29-3.85), 3.59 (95% CI 2.20-5.87), and 9.20 (95% CI 4.92-17.2), respectively. Proliferative lupus nephritis (adjusted HR 2.28, 95% CI 1.22-4.24), but not the pure membranous type (adjusted HR 1.09, 95% CI 0.38-3.14), was associated with a significant increase in mortality. The age- and sex-adjusted SMRs of SLE patients without renal involvement, those with lupus nephritis, those with proliferative nephritis, those with pure membranous nephritis, those with renal damage, and those with ESRD were 4.8 (95% CI 2.8-7.5), 9.0 (95% CI 6.7-11.9), 9.8 (95% CI 6.5-14.1), 6.1 (95% CI 2.0-14.1), 14.0 (95% CI 9.1-20.5), and 63.1 (95% CI 33.6-108.0), respectively. The life expectancy of SLE patients with renal disease and those with renal damage was reduced by 15.1 years and 23.7 years, respectively, compared to the general population. Conclusion The presence of renal disease, in particular proliferative nephritis causing renal insufficiency, significantly reduces the survival and life expectancy of SLE patients. Copyright © 2013 by the American College of Rheumatology.

Fu K.-w.,University of Hong Kong | Chan C.H.,University of Hong Kong
PLoS ONE | Year: 2013

A number of ecological studies have found a pattern of increasing suicide rates after suicides of several Asian entertainment celebrities. However, the finding may be subject to positive outcome bias where cases with no perceived impact may be routinely excluded. In this study, we deploy interrupted time-series analysis using ARIMA transfer function models to investigate systematically the impact of thirteen celebrity suicides on subsequent suicide rates in South Korea. We find that three out of eleven cases were found to be followed by a significant increase in suicide rate, while controlling for seasonality, secular trends, and unemployment rates. Such significant increases could last for nine weeks. Non-significance cases may be attributable to the small amount of media coverage, the "displacement" effect of preceding case, and the negative connotation of celebrity deaths. We therefore conclude that whether or not the impacts were detected may be largely conditioned by various contextual factors. Current evidence based on ecological studies is insufficient to draw a firm conclusion. Further studies using multiple approaches should be developed. © 2013 Fu, Chan.

Siu C.-W.,University of Hong Kong | Tse H.-F.,University of Hong Kong
Circulation: Arrhythmia and Electrophysiology | Year: 2014

Background-Little is known about the net clinical benefit of warfarin therapy in elderly patients with atrial fibrillation. Methods and Results-We studied 2339 Chinese patients with nonvalvular atrial fibrillation aged =80 years: 1805 with no antithrombotic therapy and 534 on warfarin therapy. Patients were stratified according to their CHA2DS2-VASc and HAS-BLED score. The primary end point was a composite of hospital admission with ischemic stroke or death. After 2.2-year follow-up (5199 patient-years), a primary end point had occurred for 1861 patients (79.6%): 66.9% in patients on warfarin (66.9%) compared with 80.8% in patients with no antithrombotic therapy (80.8%; hazard ratio, 0.53; 95% confidence interval, 0.48-0.58; P<0.001). This was related to substantially better mortality rate (hazard ratio, 0.40; 95% confidence interval, 0.37-0.45; P<0.0001) and ischemic stroke rate (hazard ratio, 0.64; 95% confidence interval, 0.54-0.77; P<0.0001) among patients on warfarin. For the net clinical benefit, 510 ischemic strokes and 42 intracranial hemorrhage were recorded. The annual incidence of ischemic stroke and intracranial hemorrhage was 11.3%/y and 0.6%/y, respectively, in patients prescribed no antithrombotic therapy and 7.1%/y and 1.1%/y, respectively, in those prescribed warfarin. The adjusted net clinical benefit favored warfarin for all elderly patients, and the best net benefit from warfarin was in those with high stroke and intracranial hemorrhage risk. In these high-risk patients, warfarin therapy was associated with 7.2 to 8.0 fewer events per 100 patient-years compared with no antithrombotic therapy. Conclusions-In elderly patients with atrial fibrillation, warfarin therapy is associated with lower death and ischemic stroke and an overall net clinical benefit. © 2014 American Heart Association, Inc.

Poon R.T.P.,University of Hong Kong | Borys N.,Celsion Corporation
Future Oncology | Year: 2011

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer death worldwide. No more than 30% of HCC patients are considered suitable for curative treatment because of tumor size and severity of liver impairment, among other factors. Radiofrequency ablation (RFA) monotherapy can cure small (<3 cm) HCC tumors. An adjuvant that interacts synergistically with RFA might enable curative therapy for many HCC patients with lesions >3 cm. Lyso-thermosensitive liposomal doxorubicin (LTLD) consists of the heat-enhanced cytotoxic doxorubicin within a heat-activated liposome. LTLD is infused intravenously prior to RFA. When heated to >39.5° ,°C, LTLD releases doxorubicin in high concentrations into the tumor and the tumor margins. The RFA plus LTLD combination has shown a statistically significant dose-response effect for time to treatment failure in a Phase I trial in which most subjects (62.5%) had tumors >3 cm. RFA plus LTLD is currently being evaluated in a 600-patient randomized, double-blind, dummy-controlled trial. © 2011 Future Medicine Ltd.

Shen J.,University of Hong Kong | Lam J.,University of Hong Kong
International Journal of Systems Science | Year: 2014

This article focuses on the state feedback H ∞ control problem for commensurate fractional-order systems with a prescribed H ∞ performance. For linear time-invariant fractional-order systems, a sufficient condition to guarantee stability with H ∞ performance is firstly presented. Then, by introducing a new flexible real matrix variable, the feedback gain is decoupled with complex matrix variables and further parametrised by the new flexible matrix. Moreover, iterative linear matrix inequality algorithms with initial optimisation are developed to solve the state feedback H ∞ suboptimal control problem for fractional-order systems. Finally, illustrative examples are given to show the effectiveness of the proposed approaches. © 2014 Taylor and Francis.

Zhao Y.J.,University of Hong Kong | Lam C.M.C.,University of Hong Kong | Lee H.C.,University of Hong Kong
Science Signaling | Year: 2012

The transmembrane enzyme CD38, a multifunctional protein ubiquitously present in cells, is the main enzyme that synthesizes and hydrolyzes cyclic adenosine 5′-diphosphate-ribose (cADPR), an intracellular Ca 2+-mobilizing messenger. CD38 is thought to be a type II transmembrane protein with its carboxyl-terminal catalytic domain located on the outside of the cell; thus, the mechanism by which CD38 metabolizes intracellular cADPR has been controversial. We developed specific antibodies against the amino-terminal segment of CD38 and showed that two opposing orientations of CD38, type II and type III (which has its catalytic domain inside the cell), were both present on the surface of HL-60 cells during retinoic acid-induced differentiation. When activated by interferon-γ, human primary monocytes and the monocytic U937 cell line exhibited a similar co-distribution pattern. Site-directed mutagenesis experiments showed that the membrane orientation of CD38 could be converted fromamixture of type II and type III orientations to all type III by mutating the cationic amino acid residues in the amino-terminal segment of CD38. Expression of type III CD38 construct in transfected cells led to increased intracellular concentrations of cADPR, indicating the importance of the type III orientation of CD38 to its Ca 2+ signaling function. The identification of these two forms of CD38 suggests that flipping the catalytic domain from the outside to the inside of the cell may be a mechanism regulating its signaling activity.

Cheung B.M.Y.,University of Hong Kong
Drug Safety | Year: 2011

Obesity is a major health problem worldwide. It is associated with cardiovascular diseases, diabetes mellitus and decreased longevity. In managing obesity, diet and exercise are essential; pharmacological therapy may be added for obese patients or overweight patients with cardiovascular risk factors. Sibutramine is a serotonergic and adrenergic drug that reduces food intake and increases thermogenesis. It reduces bodyweight by about 4.2kg after 12 months, and improves blood glucose and lipids; however, it can increase heart rate and blood pressure. In the SCOUT (Sibutramine Cardiovascular OUTcomes) study, sibutramine increased serious cardiovascular events, such as stroke or myocardial infarction, compared with placebo, and was consequently withdrawn from the market. The lesson learnt from this is the importance of patient selection, limiting the duration of treatment and stopping treatment in non-responders. Currently, phentermine and amfepramone (diethylpropion) are approved for short-term treatment of obesity (up to 3 months) and orlistat is approved for longer-term treatment; however, the gastrointestinal adverse effects of orlistat may be intolerable for some patients. There is now a clear need to find anti-obesity drugs that are effective and safe in the long term. © 2011 Adis Data Information BV. All rights reserved.

Chan T.M.,University of Hong Kong
Nature Reviews Nephrology | Year: 2015

Lupus nephritis is a common and severe manifestation of systemic lupus erythematosus, and an important cause of both acute kidney injury and end-stage renal disease. Despite its aggressive course, lupus nephritis is amenable to treatment in the majority of patients. The paradigm of immunosuppressive treatment for lupus nephritis has evolved over the past few decades from corticosteroids alone to corticosteroids combined with cyclophosphamide. Sequential treatment regimens using various agents have been formulated for induction and long-term maintenance therapy, and mycophenolate mofetil has emerged as a standard of care option for both induction and maintenance immunosuppressive treatment. The current era has witnessed the emergence of multiple novel therapeutic options, such as calcineurin inhibitors and biologic agents that target key pathogenetic mechanisms of lupus nephritis. Clinical outcomes have improved in parallel with these therapeutic advances. This Review discusses the evidence in support of current standard of care immunosuppressive treatments and emerging therapies, and describes their roles and relative merits in the management of patients with lupus nephritis. © 2015 Macmillan Publishers Limited. All rights reserved.

Ngan A.H.W.,University of Hong Kong
Scripta Materialia | Year: 2011

The power-law scaling of size effect of strength in micro-crystals is explained in terms of an assumed fractal geometry of the initial dislocation network. The size effect arises from the Taylor-type resistance in such a network. The power exponent of the size effect is predicted to be 3/(q + n), where q is the fractal dimension of the dislocation network, and n is the stress exponent of dislocation velocity. The theory is verified by a set of experimental strength data of Al micro-pillars. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Purpose Sociocultural factors influence psychological adjustment to cancer in Asian patients in two major ways: Prioritization of relationships over individual orientations and belief in the efficacy of interpersonal cooperation. We derived and validated among Chinese colorectal cancer (CRC) patients an instrument assessing cancer perceptions to enable the study of the sociocultural processes. Patients and methods Qualitative interviews (n=16) derived 15 items addressing interpersonal experience in Chinese CRC patients' adjustment. These 15 items and 18 corresponding self-referent items were administered to 166 Chinese CRC survivors and subjected to exploratory factor analysis (EFA) to establish the initial scale structure and reliability. The final 29 items, together with other psychometric measures, were administered to a second cohort of 215 CRC patients and subjected to confirmatory factor analysis (CFA). Results EFA (63.35% of the total variance) extracted six factors: Personal strain, socioeconomic strain, emotional strain, personal efficacy, collective efficacy, and proxy efficacy. CFA confirmed the psychometric structure [?2(df)=702.91 (368); Comparative Fit Index=0.95; Nonnormed Fit Index= 0.94; Incremental Fit Index=0.95; standardized root mean square residual=0.08] of the six factors by using a model with two latent factors: Experience and efficacy. All subscales were reliable (a=0.76-0.92). Appropriate correlations with adjustment outcomes (symptom distress, psychological morbidity, and subjective well-being), optimistic personalities, and social relational quality indicated its convergent and divergent validity. Known group comparisons (i.e., age, active treatment, and colostomy) showed its clinical utility. Conclusion The cancer experience and efficacy scale is a valid multidimensional instrument for assessing intrapersonal and interpersonal dimensions of cancer experience in Asian patients, potentiating existing patient-reported outcome measures. © Springer-Verlag 2009.

Liu H.,University of Hong Kong | Li X.,University of Hong Kong
Organic and Biomolecular Chemistry | Year: 2014

Chemical synthesis of proteins, especially those with post-translational modifications, has offered new opportunities to study the protein structure-function relationship. In the past four years, we have developed the serine/threonine ligation (STL), which involves the chemoselective reaction between peptide salicylaldehyde esters and peptides with N-terminal serine or threonine. The method has been successfully applied to the synthesis of both linear and cyclic peptides/proteins. This journal is © the Partner Organisations 2014.

Yan S.,University of Hong Kong | Young B.,University of Hong Kong
Engineering Structures | Year: 2012

This paper presents a test program on screwed connections of thin sheet steels at elevated temperatures using steady state test method. The single shear screwed connections design rules in the current North American, Australian/New Zealand and European specifications for cold-formed steel structures are not applicable to elevated temperature. A total of 102 single shear screwed connection specimens were tested at elevated temperatures. Three different thicknesses of thin sheet steels were considered in this study. The failure loads and failure modes were obtained from the tests. Several failure modes were observed including the bearing, tilting and bearing, screw shear, net section tension and material failure. The test strengths were compared with the predicted strengths using the current specifications for cold-formed steel structures. The predicted strengths were calculated using the reduced material properties obtained from tensile coupon tests at elevated temperatures. It is shown that the strengths of the single shear screwed connections predicted by the current specifications are generally conservative at elevated temperatures. © 2011 Elsevier Ltd.

Feng R.,University of Hong Kong | Young B.,University of Hong Kong
Engineering Structures | Year: 2012

This paper describes the numerical investigation of cold-formed stainless steel tubular T-joints, X-joints and X-joints with chord preload at elevated temperatures. A series of finite element analysis was performed on stainless steel tubular joints. The tubular T- and X-joints were welded from cold-formed square and rectangular hollow sections as brace and chord members. The material properties of high strength stainless steel (duplex and high strength austenitic) and normal strength stainless steel (AISI 304) at elevated temperatures were carefully incorporated in the finite element models. An extensive numerical study of 450 specimens consists of 20 T-joints, 10 X-joints and 20 X-joints with chord preload at different temperatures ranged from 22 to 870 °C was conducted. The joint strengths, failure modes and load-deformation curves of stainless steel tubular joints at elevated temperatures were obtained from the finite element analysis. The numerical results were compared with the design strengths calculated from the existing design rules for stainless steel tubular joints at normal room temperature (ambient temperature) by using the material properties of stainless steel tubes at elevated temperatures. In the calculation of the joint strengths, the reduced material property of 0.2% proof stress was used due to the deterioration of material at elevated temperatures. Furthermore, design equations for cold-formed stainless steel tubular T- and X-joints at elevated temperatures are proposed by introducing a temperature factor (ξ T). A reliability analysis was performed to assess the existing and proposed design equations. © 2011 Elsevier Ltd.

Cheung Y.-F.,University of Hong Kong
Nature Reviews Cardiology | Year: 2012

Heart failure is a major health problem in developed countries and a growing one in developing countries. Cardiac remodeling in heart failure affects myocardial mechanics, which requires comprehensive evaluation in three dimensions. The novel technique of 3D wall motion tracking applies speckle tracking technology to full volume, 3D echocardiographic datasets. Quantification of conventional and novel left ventricular (LV) parameters including volumes, ejection fraction, global and regional 3D strain, endocardial area strain, twist, and dyssynchrony, and identification of the site of latest mechanical activation are feasible on the basis of a single acquisition of a full-volume dataset. Clinical applications of 3D wall motion tracking include the assessment of global and regional LV performance in ischemic and nonischemic heart diseases, evaluation of mechanics in cardiomyopathies and congenital heart disease, potential selection of patients for cardiac resynchronization therapy and prediction of their response, and detection of subclinical cardiac dysfunction in diseases with likelihood of progression to heart failure. Technological advances with improvement in spatial and temporal resolution of this novel imaging modality are expected. Although 3D wall motion tracking is still in its infancy, this method has begun to provide new insights into LV mechanics and has already found clinical applications. Future developments in 3D assessment of right ventricular and myocardial layer-specific mechanics are awaited. © 2012 Macmillan Publishers Limited. All rights reserved.

Wong O.L.,University of Hong Kong
Social Work in Health Care | Year: 2010

This study aimed to examine the relational meaning of food, based on the results of a qualitative study of eight obese children (six male and two female) and their families in a Chinese society in Hong Kong. The children range in age from 7 to 13. Findings reveal the important bonding function of food in family relationships. Two clinical themes were identified from the data: (1) food bonding nurturer and obese child; (2) eating and the bonding relationship with extended family. Putting a child on a diet was found to disrupt the bonding between the nurturers and the obese child. Power struggles over the loyalty of the child in food provision were also observed. Implications for practice are discussed. © Taylor & Francis Group, LLC.

Chung K.K.H.,The Hong Kong Institute of Education | Ho C.S.-H.,University of Hong Kong
Journal of Learning Disabilities | Year: 2010

This study examined the relations between reading-related cognitive skills and word reading development of Chinese children with dyslexia in their Chinese language (L1) and in English (L2). A total of 84 bilingual children-28 with dyslexia, 28 chronological age (CA) controls, and 28 reading-level (RL) controls-participated and were administered measures of word reading, rapid naming, visual-orthographic skills, and phonological and morphological awareness in both L1 and L2. Children with dyslexia showed weaker performance than CA controls in both languages and had more difficulties in phonological awareness in English but not in Chinese. In addition, reading-related cognitive skills in Chinese contributed significantly to the ability to read English words, suggesting cross-linguistic transfer from L1 to L2. Results found evidence for different phonological units of awareness related to the characteristics of the different languages being learned, supporting the psycholinguistic grain size and linguistic coding differences hypotheses. © Hammill Institute on Disabilities 2010.

Zeng H.,University of Hong Kong | Dai J.,South University of Science and Technology of China | Yao W.,University of Hong Kong | Xiao D.,Oak Ridge National Laboratory | Cui X.,University of Hong Kong
Nature Nanotechnology | Year: 2012

Most electronic devices exploit the electric charge of electrons, but it is also possible to build devices that rely on other properties of electrons. Spintronic devices, for example, make use of the spin of electrons. Valleytronics is a more recent development that relies on the fact that the conduction bands of some materials have two or more minima at equal energies but at different positions in momentum space. To make a valleytronic device it is necessary to control the number of electrons in these valleys, thereby producing a valley polarization. Single-layer MoS 2 is a promising material for valleytronics because both the conduction and valence band edges have two energy-degenerate valleys at the corners of the first Brillouin zone. Here, we demonstrate that optical pumping with circularly polarized light can achieve a valley polarization of 30% in pristine monolayer MoS 2. Our results, and similar results by Mak et al., demonstrate the viability of optical valley control and valley-based electronic and optoelectronic applications in MoS 2 monolayers. © 2012 Macmillan Publishers Limited. All rights reserved.

Zhang Y.,University of Hong Kong | Kwok S.,University of Hong Kong
Astrophysical Journal | Year: 2011

We report the first detection of buckminsterfullerene (C60) in a protoplanetary nebula. The vibrational transitions of C60 at 7.0, 17.4, and 18.9μm are detected in the Spitzer/Infrared Spectrograph spectrum of IRAS 01005+7910. This detection suggests that fullerenes are formed shortly after the asymptotic giant branch but before the planetary nebulae stage. A comparison with the observations of C60 in other sources is made and the implication for circumstellar chemistry is discussed. © 2011. The American Astronomical Society. All rights reserved.

Wong H.-L.,University of Hong Kong | Wong W.-T.,University of Hong Kong | Yam V.W.-W.,University of Hong Kong
Organic Letters | Year: 2012

A series of diarylethene-containing N ^C chelated thienylpyridine-bis(alkynyl)borane complexes has been designed and synthesized. Their photophysical and photochromic properties have been investigated and presented. The characteristic low-energy absorption band of their closed forms could be readily tuned from the visible range to the near-infrared region. © 2012 American Chemical Society.

Pan H.,University of Hong Kong | Darvell B.W.,Kuwait University
Crystal Growth and Design | Year: 2010

Carbonate is present in biological apatites (BAp) (enamel, dentine, bone, and pathological calcifications) by substitution at phosphate and hydroxide sites, tending to increase its solubility in comparison with pure hydroxyapatite (HAp). The role of solution carbonate, however, is poorly understood. Using the solid titration method, it was found that the apparent solubility of HAp increased greatly with an increase in pCO2, and was sensitively-dependent at low values. No other phase was formed at the end point except HAp, and in particular no dicalcium phosphate dihydrate (DCPD) was found. However, no carbonate was detected in the end-point solid except for a small amount at pH ∼ 7.4, pCO2 = 0.01-1.0 bar. The implications of these results need further investigation, bearing as they do on a central topic in oral chemistry. © 2010 American Chemical Society.

Wei W.I.,University of Hong Kong | Ho W.-K.,University of Hong Kong
Laryngoscope | Year: 2010

Transoral robotic nasopharyngectomy was carried out for a patient who developed recurrent nasopharyngeal cancer after radiotherapy. The tumor in the left lateral wall of the nasopharynx was exposed after splitting the soft palate and a curative resection, including the medial crus of the eustachian tube was carried out under the three-dimensional 0° camera. The operative procedure was uncomplicated, blood loss was minimal and the patient recovered smoothly. The camera of the surgical robot provided superb visualization of the operative field and the maneuverability of the robotic arms with the Endowrist design allowed adequate tumor extirpation. The morbidity associated with the procedure was minimal, and this surgical procedure can be applied for resection of small and favorably located residual or recurrent nasopharyngeal cancer or other appropriate pathologies in the region. © 2010 The American Laryngological, Rhinological and Otological Society, Inc.

Greenland K.B.,University of Hong Kong
Current Opinion in Anaesthesiology | Year: 2012

Purpose of review: This review will focus on two key aspects of difficult airway management in an ambulatory surgical center (ASC). First, the selection process of patients with known difficult airways suitable for this environment, and second, the requirements of a difficult airway cart to manage unexpected airway problems. Recent findings: The decision whether to manage a patient with a previously documented difficult airways in an ASC requires a multidisciplinary approach. Many factors will influence this decision including the cause and severity of the airway problem, the type of procedure, the experience of the perioperative staff, and the availability of difficult airway management devices.Unexpected difficult airways will always occur in anesthesia. Difficult airway carts are, therefore, a requirement for any area in which anesthesia is to be conducted. The contents of these carts should reflect the need to maintain patient oxygenation to avoid morbidity and mortality. Regular training sessions should include both technical training in the use of equipment and nontechnical training to improve interpersonal communication during crises. Summary: The management of ambulatory surgical practices must provide suitable difficult airway management equipment as well as technical and nontechnical training. Patients may present to an ASC with expected and unexpected difficult airways. Appropriate management of these patients requires advance planning to avoid poor outcomes. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Understanding environmental and biological influences on the dynamics of microbial communities has received great attention in microbial ecology. Here, utilizing large time-series 16S rRNA gene data, we show that in activated sludge of an environmentally important municipal wastewater treatment plant, 5-year temporal dynamics of bacterial community shows no significant seasonal succession, but is consistent with deterministic assemblage by taxonomic relatedness. Biological interactions are dominant drivers in determining the bacterial community assembly, whereas environmental conditions (mainly sludge retention time and inorganic nitrogen) partially explain phylogenetic and quantitative variances and indirectly influence bacterial assembly. We demonstrate a correlation-based statistical method to integrate bacterial association networks with their taxonomic affiliations to predict community-wide co-occurrence and co-exclusion patterns. The results show that although taxonomically closely related bacteria tend to positively co-occur (for example, out of a cooperative relationship), negative co-excluding correlations are deterministically observed between taxonomically less related species, probably implicating roles of competition in determining bacterial assembly. Overall, disclosures of the positive and negative species-species relations will improve our understanding of ecological niches occupied by unknown species and help to predict their biological functions in ecosystems.

Leung T.H.-Y.,University of Hong Kong | Ngan H.Y.-S.,University of Hong Kong
Cancer Research | Year: 2010

Identification of proteins that are involved in the sensitivity of radiotherapy of cancers is important to enhance the response to cancer treatment. Expression of TAp73 is associated with the sensitivity of radiotherapy in cervical cancer patients, suggesting it plays an important role in controlling radiosensitivity. Here, by using yeast two-hybrid system, we identify breast cancer-associated gene 3 (BCA3) as the first and novel protein interacting partner of TAp73. By coimmunoprecipitation and Western blot analysis, we confirm that TAp73 binds with and stabilizes BCA3 in cervical cancer cell line HeLa. Immunofluorescence staining indicates that BCA3 is localized in the cytoplasm and nucleus. Interestingly, when coexpressed with TAp73, BCA3 interacts and colocalizes with TAp73 at the mitochondria. Mutagenesis reveals that the oligomerization domain of TAp73 is responsible for the interaction with BCA3. Furthermore, BCA3 augments the transactivation activity of TAp73 on bax promoter and protein expression. In addition, the expression of BCA3 also increases the sensitivity of TAp73-transfected cells in response to γ-irradiation-induced apoptosis. Western blot analysis also shows that TAp73 and BCA3 induce activation of caspase-7 and caspase-9. In summary, these findings suggested that BCA3 is a novel protein partner of TAp73, and they cooperate with each other to exert tumor-suppressive functions and sensitize the response of cervical cancer cells to radiotherapy. ©2010 AACR.

Li J.,University of Hong Kong | Shen Y.,University of Hong Kong | Lam E.Y.,University of Hong Kong
Optics Express | Year: 2012

Source mask optimization (SMO) is a useful technique for printing the integrated circuit (IC) on a wafer with increasingly smaller feature size. However, complex SMO algorithms generally lead to undesirably long runtime resulting from an optimization of largely identical regions over the whole mask pattern. In this work, a weighted SMO scheme incorporating both an awareness of the hotspots and robustness against process variations is proposed. We show how optimal solutions are reached with fewer iterations by applying various degrees of correction in the corresponding regions. The proposed method includes identifying the hotspots and combining a weight matrix to the cost function for adjustment and control. Simulation results are compared with the mask optimization (under a fixed source) and conventional SMO to illustrate the performance improvement in terms of pattern fidelity, convergence rate and process window size. © 2012 Optical Society of America.

Zhao G.,University of Hong Kong | Cawood P.A.,University of St. Andrews
Precambrian Research | Year: 2012

China contains three major Precambrian blocks, the North China, South China and Tarim cratons, separated and sutured by Phanerozoic orogenic belts. The North China Craton (NCC) contains rocks as old as 3.8Ga, but is dominated by Neoarchean igneous rocks that were formed during two magmatic events at 2.8-2.7Ga and 2.55-2.50Ga. The 2.8-2.7Ga magmatic pulse is considered as a major phase of juvenile crustal growth in the craton, though exposure of these rocks is limited. The 2.55-2.50Ga rocks make up ~80% of Archean basement in the NCC, but their rock associations, structural patterns, and metamorphic age and P-T paths in the eastern and western parts (Eastern and Western blocks) are different from those in the central part (Trans-North China Orogen). In the Eastern and Western blocks, the end-Neoarchean rocks are exposed as gneissic domes and dominated by tonalitic-trondhjemitic-granodioritic (TTG) gneisses and mafic to komatiitic rocks that were metamorphosed at ~2.5Ga, along anticlockwise P-T paths involving isobaric cooling, that is interpreted to reflect underplating of mantle-derived magmas. In the Trans-North China Orogen, the end-Neoarchean rocks occur as linear structural belts and are composed of arc-related granitoids and volcanic rocks that formed in a supra-subduction zone setting and were metamorphosed at ~1.85Ga along a clockwise P-T paths involving isothermal decompression in a continent-continent collisional setting. Although magmatic arc models can explain the origin of the 2.55-2.50Ga TTG rocks in the Eastern and Western blocks, a mantle plume model is favored because it best explains many other features, including the formation of komatiitic rocks. The 2.55-2.50Ga rocks and associated Paleoproterozoic rocks in the Trans-North China Orogen exhibit the same structural and metamorphic characteristics that typify continental margin arcs and collisional belts. Spatially, Paleoproterozoic rocks in the NCC are related to collisional assembly of the disparate parts of the Eastern and Western blocks including a ~1.95Ga collisional event that led to amalgamation of the Yinshan and Ordos blocks to form the Western Block, which then collided with the Eastern Block to form the Trans-North China Orogen at ~1.85Ga. Following the final assembly at ~1.85Ga, the interior of the NCC underwent on-going extension, leading to widespread emplacement of 1.80-1.75Ga mafic dyke swarms, 1.75-1.68Ga anorthosite-mangerite-granite-rapakivi suites, and deposition of Mesoproterozoic and Neoproterozoic strata. Meanwhile, a large Paleo-Mesoproterozoic volcanic belt (Xiong'er Group) developed on the southern margin of the NCC, and is variously interpreted as an intracontinental rift zone or an Andean-type continental margin arc. In the late Mesoproterozoic, the northern margin of the NCC underwent rifting (Zhaertai-Bayan Obo rift zone), coincident with breakup of the Columbia (Nuna) supercontinent.The South China Craton consists of the Yangtze and Cathaysia blocks, which are considered to have collided along the Jiangnan Belt in the Neoproterozoic. Archean and Paleoproterozoic basement rocks in the Yangtze Block are only locally exposed. The late Mesoproterozoic to early Neoproterozoic folded belts in the Yangtze Block are divided into the Jiangnan Belt in the southeast and the Panxi-Hannan Belt in the west and north. The former is dominated by early Neoproterozoic metamorphosed volcanic-sedimentary strata intruded by middle Neoproterozoic peraluminous (S-type) granites and unconformably overlain by the middle Neoproterozoic Banxi Group and its equivalents. The Panxi-Hannan Belt consists of late Mesoproterozoic to early Neoproterozoic metamorphosed volcanic-sedimentary units and plutonic complexes. A number of mutually exclusive models (e.g. plume-rift, slab-arc, plate-rift, etc.) have been proposed for these belts. The Cathaysia Block is composed predominantly of Neoproterozoic basement rocks with Paleoproterozoic rocks only exposed in southwest Zhejiang and north Fujian, and Mesoproterozoic rocks limited to Hainan Island. The Paleoproterozoic rocks consist of 1890-1830Ma granitoids and 1850-1815Ma supracrustal rocks, which were metamorphosed at 1.89-1.88Ga and locally reworked at 250-230Ma. Neoproterozoic rocks make up ~90% of the Precambrian basement in the Cathaysia Block and mainly consist of volcanic-sedimentary strata metamorphosed from greenschist to granulite facies. Some of the volcanic rocks have arc affinities, suggesting the existence of a Neoproterozoic magmatic arc in the Cathaysia Block. The Neoproterozoic rocks were metamorphosed at 460-420Ma. The tectonic setting of this event has been related to both intracontinental orogeny and continental margin subduction and collision.The Precambrian basement of the Tarim Craton consists of Neoarchean and Paleoproterozoic rocks and late Mesoproterozoic to early-middle Neoproterozoic sedimentary and volcanic strata metamorphosed at greenschist and blueschist facies, which are unconformably overlain by unmetamorphosed late Neoproterozoic (Sinian) cover. The Neoarchean and Paleoproterozoic rocks are exposed in the Kulukatage and Dunhuang complexes on the northern and northeastern margins of the craton, respectively. The Neoarchean rocks consist of granitoid rocks and minor supracrustal rocks, including TTG gneisses, calc-alkaline granites and Kf-granites, most of which were emplaced at 2.6-2.50Ga. The Paleoproterozoic basement rocks are also composed of granitoid and supracrustals rocks (Xingditage and Dunhuang groups), of which the granitoids were emplaced in two stages at 2.45-2.35Ga and ~1.9Ga. In the Kulukatage Complex, the Neoarchean and Paleoproterozoic rocks underwent metamorphic events at 1.9-1.8Ga and 1.1-1.0Ga that are related to assembly of the Columbia (Nuna) and Rodinia supercontinents, respectively. In the Dunhuang Complex, Archean rocks underwent metamorphic events at ~2.5Ga and 1.9-1.8Ga, similar to two major metamorphic events occurring in the Western Block of the NCC, leading to speculation that the complex is the western extension of the Alax Complex of the NCC. Late Mesoproterozoic to early-middle Neoproterozoic metamorphosed strata are exposed on the peripheral margins of the Tarim Craton and are considered to have formed in Andean-type continental margins that were deformed and metamorphosed between 1.0Ga and 0.9Ga, probably related to the assembly of Rodinia. During middle Neoproterozoic to Cambrian time, the Tarim Craton became a stable platform overlain by middle-late Neoproterozoic to Cambrian unmetamorphosed cover, of which the middle-late Neoproterozoic units contain four sequences of tillite correlated with the global snowball Earth events. Widespread middle to late Neoproterozoic ultramafic-mafic complexes and mafic dyke swarms with the Tarim Craton are related to a mantle plume event that led to the final breakup of Rodinia. © 2012 Elsevier B.V..

Gao X.L.,University of Hong Kong
Journal of Immigrant and Minority Health | Year: 2011

The impact of acculturation on systemic health has been extensively investigated and is regarded as an important explanatory factor for health disparity. However, information is limited and fragmented on the oral health implications of acculturation. This study aimed to review the current evidence on the oral health impact of acculturation. Papers were retrieved from five electronic databases. Twenty-seven studies were included in this review. Their scientific quality was rated and key findings were summarized. Seventeen studies investigated the impacts of acculturation on the utilization of dental services; among them, 16 reported positive associations betwen at least one acculturation indicator and use of dental services. All 15 studies relating acculturation to oral diseases (dental caries and periodontal disease) suggested better oral health among acculturated individuals. Evidence is lacking to support that better oral health of acculturated immigrants is attributable to their improved dental attendance. Further researches involving other oral health behaviors and diseases and incorporating refined acculturation scales are needed. Prospective studies will facilitate the understanding on the trajectory of immigrants' oral health along the acculturation continuum. © 2010 The Author(s).

Tsao S.-W.,University of Hong Kong | Tsang C.M.,University of Hong Kong | To K.-F.,Chinese University of Hong Kong | Lo K.-W.,Chinese University of Hong Kong
Journal of Pathology | Year: 2015

The close association of Epstein-Barr virus (EBV) infection with non-keratinizing nasopharyngeal carcinomas and a subset of gastric carcinomas suggests that EBV infection is a crucial event in these cancers. The difficulties encountered in infecting and transforming primary epithelial cells in experimental systems suggest that the role of EBV in epithelial malignancies is complex and multifactorial in nature. Genetic alterations in the premalignant epithelium may support the establishment of latent EBV infection, which is believed to be an initiation event. Oncogenic properties have been reported in multiple EBV latent genes. The BamH1 A rightwards transcripts (BART s) and the BART -encoded microRNAs (miR-BART s) are highly expressed in EBV-associated epithelial malignancies and may induce malignant transformation. However, enhanced proliferation may not be the crucial function of EBV infection in epithelial malignancies, at least in the early stages of cancer development. EBV-encoded gene products may confer anti-apoptotic properties and promote the survival of infected premalignant epithelial cells harbouring genetic alterations. Multiple EBV-encoded microRNAs have been reported to have immune evasion functions. Genetic alterations in host cells, as well as inflammatory stroma, could modulate the expression of EBV genes and alter the growth properties of infected premalignant epithelial cells, encouraging their selection during carcinogenesis. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Sun D.,University of Washington | Aivazian G.,University of Washington | Jones A.M.,University of Washington | Ross J.S.,University of Washington | And 3 more authors.
Nature Nanotechnology | Year: 2012

The combination of its high electron mobility, broadband absorption and ultrafast luminescence make graphene attractive for optoelectronic and photonic applications, including transparent electrodes, mode-locked lasers and high-speed optical modulators. Photo-excited carriers that have not cooled to the temperature of the graphene lattice are known as hot carriers, and may limit device speed and energy efficiency. However, their roles in charge and energy transport are not fully understood. Here, we use time-resolved scanning photocurrent microscopy to demonstrate that hot carriers, rather than phonons, dominate energy transport across a tunable graphene p-n junction excited by ultrafast laser pulses. The photocurrent response time varies from 1.5 ps at room temperature to 4 ps at 20 K, implying a fundamental bandwidth of ∼500 GHz (refs 12, 13, 21). Gate-dependent pump-probe measurements demonstrate that both thermoelectric and built-in electric field effects contribute to the photocurrent, with the contribution from each depending on the junction configuration. The photocurrent produced by a single pulsed laser also displays multiple polarity reversals as a function of carrier density, which is a possible signature of impact ionization. © 2012 Macmillan Publishers Limited. All rights reserved.

Chou K.-L.,University of Hong Kong | Liang K.,University of Hong Kong | Sareen J.,University of Manitoba
Journal of Clinical Psychiatry | Year: 2011

Objective: The objective of this study is to document the prevalence of social isolation from close friends and religious group members and to test the association of having infrequently contacted close friends and members of religious groups with the current DSM-IV mood, anxiety, and substance use disorders. Method: We conducted a secondary data analysis based on a cross-sectional, population-based study conducted in 2004-2005 that consists of a nationally representative sample of 34,653 American community-dwelling adults aged 18 years and older. Mood, anxiety, and substance use disorders were assessed using the Alcohol Use Disorder and Associated Disabilities Interview Schedule-DSM-IV version. Due to missing values for social network characteristics, we focused on 33,368 subjects in this study. Results: We found that many Americans lacked frequently contacted close friends (10.1%; 95% CI, 9.6%-10.6%) or religious group members (58.7%; 95% CI, 57.5%-59.9%) in their social network. After adjusting for sociodemographic variables, lifetime diagnosis of the disorder in question, and social isolation in terms of 10 other social ties, we found that the absence of close friends was associated (P < .01) with an increased risk of major depressive disorder, dysthymic disorder, social phobia, and generalized anxiety disorder; the absence of frequently contacted religious group members in a network was positively related (P < .01) to alcohol abuse and dependence, drug abuse, and nicotine dependence. Conclusions: These results suggest that social isolation is common in the United States and is associated with a higher risk of mental health problems. Results provide valuable information for prevention and treatment. © Copyright 2011 Physicians Postgraduate Press, Inc.

Jia N.,University of Hong Kong | Lam E.Y.,University of Hong Kong
Optics Express | Year: 2011

Optical lithography has enabled the printing of progressively smaller circuit patterns over the years. However, as the feature size shrinks, the lithographic process variation becomes more pronounced. Source-mask optimization (SMO) is a current technology allowing a co-design of the source and the mask for higher resolution imaging. In this paper, we develop a pixelated SMO using inverse imaging, and incorporate the statistical variations explicitly in an optimization framework. Simulation results demonstrate its efficacy in process robustness enhancement. © 2011 Optical Society of America.

Yuan Y.,University of Houston | Yin G.,University of Hong Kong
Statistics in Medicine | Year: 2011

In oncology, dose escalation is often carried out to search for the maximum tolerated dose (MTD) in phase I clinical trials. We propose a Bayesian hybrid dose-finding method that inherits the robustness of model-free methods and the efficiency of model-based methods. In the Bayesian hypothesis testing framework, we compute the Bayes factor and adaptively assign a dose to each cohort of patients based on the adequacy of the dose-toxicity information that has been collected thus far. If the data observed at the current treatment dose are adequately informative about the toxicity probability of this dose (e.g. whether this dose is below or above the MTD), we make the decision of dose assignment (e.g. either to escalate or to de-escalate the dose) directly without assuming a parametric dose-toxicity curve. If the observed data at the current dose are not sufficient to deliver such a definitive decision, we resort to a parametric dose-toxicity curve, such as that of the continual reassessment method (CRM), in order to borrow strength across all the doses under study to guide dose assignment. We examine the properties of the hybrid design through extensive simulation studies, and also compare the new method with the CRM and the '3 + 3' design. The simulation results show that our design is more robust than parametric model-based methods and more efficient than nonparametric model-free methods. © 2011 John Wiley & Sons, Ltd.

Seneviratne C.J.,University of Hong Kong
The Chinese journal of dental research : the official journal of the Scientific Section of the Chinese Stomatological Association (CSA) | Year: 2011

Dental plaque is an archetypical biofilm composed of a complex microbial community. It is the aetiological agent for major dental diseases such as dental caries and periodontal disease. The clinical picture of these dental diseases is a net result of the cross-talk between the pathogenic dental plaque biofilm and the host tissue response. In the healthy state, both plaque biofilm and adjacent tissues maintain a delicate balance, establishing a harmonious relationship between the two. However, changes occur during the disease process that transform this 'healthy' dental plaque into a 'pathogenic' biofilm. Recent advances in molecular microbiology have improved the understanding of dental plaque biofilm and produced numerous clinical benefits. Therefore, it is imperative that clinicians keep abreast with these new developments in the field of dentistry. Better understanding of the molecular mechanisms behind dental diseases will facilitate the development of novel therapeutic strategies to establish a 'healthy dental plaque biofilm' by modulating both host and microbial factors. In this review, the present authors aim to summarise the current knowledge on dental plaque as a microbial biofilm and its properties in oral health and disease.

Zhang X.,Huazhong University of Science and Technology | Huang G.Q.,University of Hong Kong
International Journal of Production Economics | Year: 2010

This paper deals with simultaneous configuration of platform products and supply chains. The supply chain consists of one manufacturer and multiple cooperative suppliers. A common platform is shared for developing/configuring the product family with variant modules which are substitutable in the sense that high-performance module options can replace low-performance ones. As the customer in the supply chain, the manufacturer takes its leading role by making the first move to produce decisions on platform products configuration (PPC) and supplier selection. The manufacturer and concerned suppliers then move cooperatively to make their ordering and pricing decisions with a common objective to maximize their joint payoffs. We derive the optimal solution ranges for this two-moves dynamic game according to Nash's bargaining model. An iterative algorithm is developed to find the subgame perfect equilibrium. A numerical study is conducted through a series of simulation experiments to illustrate how useful insights about the mutual impacts between the PPC and SCC (supply chain configuration) decisions can be obtained from the proposed game models and solution procedure. The results are further compared with those obtained in a previous study with non-cooperative suppliers. The comparative study allows us to appreciate managerial measures under different supply chain coordination schemes. It is found that a supply chain with cooperative suppliers is more effective by using the lot-for-lot policy and more competitive by accommodating higher product variety. © 2009 Elsevier B.V. All rights reserved.

BACKGROUND: Populations in Asia are not only at risk of harm to their health through environmental degradation as a result of worsening pollution problems but also constantly threatened by recurring and emerging influenza epidemics and. pandemics. Situated in the area with the world's fastest growing economy and close to hypothetical epicenters of influenza transmission, Hong Kong offers a special opportunity for testing environmental management and public health surveillance in the region. In the Public Health and Air Pollution in Asia (PAPA*) project, the Hong Kong research team assessed the health effects of air pollution and influenza as well as the interaction between them. The team also assessed disparities in the health effects of air pollution between relatively deprived and more affluent areas in Hong Kong. The aim was to provide answers to outstanding research questions relating to the short-term effects of air pollution on mortality and hospital admissions; the health effects of influenza with a view to validating different measures of influenza activity according to virologic data; the confounding effects of influenza on estimates of the health effects of air pollution; the modifying effects of influenza on the health effects of air pollution; and the modifying effects of neighborhood social deprivation on the health effects of air pollution. DATA: Data on mortality and hospital admissions for all natural causes, as well as the subcategories of cardiovascular diseases (CVD) and respiratory diseases (RD), were derived from the Hong Kong Census and Statistics Department and the Hospital Authority. Daily concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with an aerodynamic diameter < or = 10 pm (PM10); and ozone (O3) were derived from eight monitoring stations with hourly data that were at least 75% complete during the study period. Three measures of influenza and respiratory syncytial virus (RSV) activity were derived from positive isolates of specimens in the virology laboratory of Queen Mary Hospital (QMH), the main clinical teaching center at The University of Hong Kong and part of the Hong Kong Hospital Authority network of teaching hospitals: influenza intensity (defined as the weekly proportion of positive isolates of influenza in the total number of specimens received for diagnostic tests); the presence of influenza epidemic (defined as a period when the weekly frequency of these positive isolates is > or = 4% of the annual total number of positive isolates [i.e., twice the expected mean value] in two or more consecutive weeks); and influenza predominance (defined as a period of influenza epidemic when the weekly frequency of RSV was less than 2% for two or more consecutive weeks).

Khambay B.,University of Hong Kong | Ullah R.,Birmingham Dental Hospital
International Journal of Oral and Maxillofacial Surgery | Year: 2015

Since the introduction of three-dimensional (3D) orthognathic planning software, studies have reported on their predictive ability. The aim of this study was to highlight the limitations of the current methods of analysis. The predicted 3D soft tissue image was compared to the postoperative soft tissue. For the full face, the maximum and 95th and 90th percentiles, the percentage of 3D mesh points ≤2 mm, and the root mean square (RMS) error, were calculated. For specific anatomical regions, the percentage of 3D mesh points ≤2 mm and the distance between the two meshes at 10 landmarks were determined. For the 95th and 90th percentiles, the maximum difference ranged from 7.7 mm to 2.2 mm and from 3.7 mm to 1.5 mm, respectively. The absolute mean distance ranged from 0.98 mm to 0.56 mm and from 0.91 mm to 0.50 mm, respectively. The percentage of mesh with ≤2 mm for the full face was 94.4-85.2% and 100-31.3% for anatomical regions. The RMS error ranged from 2.49 mm to 0.94 mm. The majority of mean linear distances between the surfaces were ≤0.8 mm, but increased for the mean absolute distance. At present the use of specific anatomical regions is more clinically meaningful than the full face. It is crucial to understand these and adopt a protocol for conducting such studies. © 2014 International Association of Oral and Maxillofacial Surgeons.

Yeung W.L.,University of Hong Kong
Expert Systems with Applications | Year: 2011

Web services have emerged as the building blocks of a service-oriented architecture that supports not only enterprise application integration (EAI) and business process management (BPM) within an organization but also B2B collaboration based on business process integration. The web services choreography approach to B2B process integration allows business partners to orchestrate their own web services privately, while conforming with an agreed specification of the common ordering conditions and constraints under which messages are exchanged among partners' web services. In this approach, choreography conformance is an essential requirement for the successful implementation of collaborative processes. A formal approach to web services composition and conformance verification based on WS-CDL and WS-BPEL is presented. This approach involves model checking as an automated means of verifying choreography conformance. The main contributions include a precise notion of choreography conformance on which verification is based as well as support for the complementary use of visual modeling (e.g. UML) and standard WS-* notations in composition. © 2010 Elsevier Ltd. All rights reserved.

Jiang Y.,University of Hong Kong | Szeto W.Y.,University of Hong Kong
Transportmetrica A: Transport Science | Year: 2015

This paper proposes a bi-level optimisation framework for time-dependent discrete road network design that considers health impacts. A general health cost function is proposed and captured in the framework. The function simultaneously considers the health impacts of road traffic emissions, noise, and accidents due to network expansion. To solve the problem, the artificial bee colony (ABC) algorithm is proposed to search the network design solutions of the upper-level problem, while the method of successive averages and the Frank–Wolfe algorithm are adopted to solve the lower-level time-dependent land-use transportation problem. A repairing procedure is proposed to remedy infeasible solutions. A numerical study is set up to illustrate the conflict between maximising consumer surplus and minimising the health cost. This paper also reveals a paradox phenomenon that with an increasing amount of emissions, the health cost decreases. Moreover, the existence of a health inequity between different residential zones is demonstrated. A modified Sioux Falls network is adopted to show the performance of the solution algorithm as well as the effectiveness of the proposed repairing procedure. © 2014, © 2014 Hong Kong Society for Transportation Studies Limited.

Chan K.K.,University of Hong Kong
The Journal of endocrinology | Year: 2014

Ovarian cancer cells express both estrogen receptor α (ERα) and ERβ, and hormonal therapy is an attractive treatment option because of its relatively few side effects. However, estrogen was previously shown to have opposite effects in tumors expressing ERα compared with ERβ, indicating that the two receptor subtypes may have opposing effects. This may explain the modest response to nonselective estrogen inhibition in clinical practice. In this study, we aimed to investigate the effect of selectively targeting each ER subtype on ovarian cancer growth. Ovarian cancer cell lines SKOV3 and OV2008, expressing both ER subtypes, were treated with highly selective ER modulators. Sodium 3'-(1-(phenylaminocarbonyl)-3,4-tetrazolium)-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate (XTT) assay revealed that treatment with 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP) (ERα antagonist) or 2,3-bis(4-hydroxy-phenyl)-propionitrile (DPN) (ERβ agonist) significantly suppressed cell growth in both cell lines. In contrast, 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT) (ERα agonist) or 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]-pyrimidin-3-yl]phenol (PHTPP) (ERβ antagonist) significantly enhanced cell growth. These results were confirmed on a xenograft model where SKOV3 cells were injected s.c. into ovariectomized mice. We observed that the average size of xenografts in both the DPN-treated group and the MPP-treated group was significantly smaller than that for the vehicle-treated group. In addition, we found that phospho-AKT expressions in SKOV3 cells were reduced by 80% after treatment with MPP and DPN, indicating that the AKT pathway was involved. The combined treatment with MPP and DPN had a synergistic effect in suppressing ovarian cancer cell growth. Our findings indicate that targeting ER subtypes may enhance the response to hormonal treatment in women with ovarian cancer.

Dai B.,University of Hong Kong
Nature Nanotechnology | Year: 2016

Phototaxis is commonly observed in motile photosynthetic microorganisms. For example, green algae are capable of swimming towards a light source (positive phototaxis) to receive more energy for photosynthesis, or away from a light source (negative phototaxis) to avoid radiation damage or to hide from predators. Recently, with the aim of applying nanoscale machinery to biomedical applications, various inorganic nanomotors based on different propulsion mechanisms have been demonstrated. The only method to control the direction of motion of these self-propelled micro/nanomotors is to incorporate a ferromagnetic material into their structure and use an external magnetic field for steering. Here, we show an artificial microswimmer that can sense and orient to the illumination direction of an external light source. Our microswimmer is a Janus nanotree containing a nanostructured photocathode and photoanode at opposite ends that release cations and anions, respectively, propelling the microswimmer by self-electrophoresis. Using chemical modifications, we can control the zeta potential of the photoanode and program the microswimmer to exhibit either positive or negative phototaxis. Finally, we show that a school of microswimmers mimics the collective phototactic behaviour of green algae in solution. © 2016 Nature Publishing Group

Li M.,University of Hong Kong | Gu J.-D.,University of Hong Kong
Applied Microbiology and Biotechnology | Year: 2011

Anaerobic ammonium oxidation (anammox), the biochemical process oxidizing ammonium into dinitrogen gas using nitrite as an electron acceptor, has only been recognized for its significant role in the global nitrogen cycle not long ago, and its ubiquitous distribution in a wide range of environments has changed our knowledge about the contributors to the global nitrogen cycle. Currently, several groups of methods are used in detection of anammox bacteria based on their physiological and biochemical characteristics, cellular chemical composition, and both 16S rRNA gene and selective functional genes as biomarkers, including hydrazine oxidoreductase and nitrite reductase encoding genes hzo and nirS, respectively. Results from these methods coupling with advances in quantitative PCR, reverse transcription of mRNA genes and stable isotope labeling have improved our understanding on the distribution, diversity, and activity of anammox bacteria in different environments both natural and engineered ones. In this review, we summarize these methods used in detection of anammox bacteria from various environments, highlight the strengths and weakness of these methods, and also discuss the new development potentials on the existing and new techniques in the future. © 2011 The Author(s).

Song Y.,University of Hong Kong | Shum H.C.,University of Hong Kong
Langmuir | Year: 2012

We develop an approach to fabricate monodisperse water-in-water-in-water (w/w/w) double emulsion in microfluidic devices. A jet of aqueous solution containing two incompatible solutes, dextran and polyethylene glycol (PEG), is periodically perturbed into water-in-water (w/w) droplets. By extracting water out of the w/w droplet, the solute concentrations in the droplet phase increase; when the concentrations exceed the miscibility limit, the droplet phase separates into two immiscible phases. Consequently, PEG-rich droplets are formed within the single emulsion templates. These PEG-rich droplets subsequently coalesce with each other, resulting in transiently stable w/w/w double emulsions with a high degree of size uniformity. These double emulsions are free of organic solvents and thus are ideal for use as droplet-vessels in protein purification, as microreactors for biochemical reactions, and as templates for fabrication of biomaterials. © 2012 American Chemical Society.

Guo Y.,CAS Institute of Chemistry | Xu L.,CAS Institute of Chemistry | Liu H.,CAS Institute of Chemistry | Li Y.,CAS Institute of Chemistry | Che C.-M.,University of Hong Kong
Advanced Materials | Year: 2015

Self-assembled functional nanoarchitectures are employed as important nanoscale building blocks for advanced materials and smart miniature devices to fulfi ll the increasing needs of high materials usage effi ciency, low energy consumption, and high-performance devices. One-dimensional (1D) crystalline nanostructures, especially molecule-composed crystalline nanostructures, attract signifi cant attention due to their fascinating infusion structure and functionality which enables the easy tailoring of organic molecules with excellent carrier mobility and crystal stability. In this review, we discuss the recent progress of 1D crystalline self-assembled nanostructures of functional molecules, which include both a small molecule-derived and a polymer-based crystalline nanostructure. The basic principles of the molecular structure design and the process engineering of 1D crystalline nanostructures are also discussed. The molecular building blocks, self-assembly structures, and their applications in optical, electrical, and photoelectrical devices are overviewed and we give a brief outlook on crucial issues that need to be addressed in future research endeavors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Au W.Y.,University of Hong Kong
Hong Kong Medical Journal | Year: 2011

Arsenic trioxide has been used in traditional Chinese medicine for over 5000 years, but lost its appeal due to its toxicity. It was rediscovered in western medicine and enjoyed a renaissance from 1830 to 1930, as the first effective chemotherapy against syphilis, parasites and leukaemia. These years were also a time of political turmoil in China. The Nanking treaty (29 August 1842) turned Hong Kong into a colony, while the Xinhai Revolution (10 October 1911) gave birth to a republic of China. Arsenic returned to China and Hong Kong with the establishment of the first medical schools from 1887 to 1920. Until 1950, oral arsenic trioxide was the standard anti-leukaemic treatment in Queen Mary Hospital. The advent of alkylating chemotherapeutic agents replaced arsenic trioxide in Hong Kong and around the world. In the 1970s, however, the specific activity of arsenic trioxide against acute promyelocytic leukaemia was re-discovered during the Cultural Revolution in Harbin, China. In 1997, Hong Kong was returned to China. In the same year, arsenic trioxide returned to the world stage. Intravenous arsenic trioxide became the worldwide standard therapy for relapsed acute promyelocytic leukaemia. Oral administration of arsenic trioxide was revived in Hong Kong in 2000. This resulted in the first locally produced, registered, patented prescription drug in Hong Kong. Pending imminent manufacture, this product is poised to revolutionise acute promyelocytic leukaemia care and may hold the key to saving the lives of acute promyelocytic leukaemia patients worldwide. The remarkable journey of arsenic in the setting of medical history of China and Hong Kong is reviewed.

Wang K.,Nanjing University of Science and Technology | Chen M.Z.Q.,University of Hong Kong
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2012

This brief is concerned with the realization problem of biquadratic impedances, motivated by the recent development in passive mechanical control. This brief generalizes a realization procedure of a special class of biquadratic impedances to a more general form, and the resulting series-parallel RLC networks whose elements are no more than those in Bott-Duffin's networks are obtained without minimization. The realizability condition is proven by providing a constructive synthesis procedure. The series-parallel network obtained contains elements no more than those of Bott-Duffin's network when the impedance is nonregular. © 2004-2012 IEEE.

Jim C.Y.,University of Hong Kong
Urban Ecosystems | Year: 2014

Hong Kong's rugged topography demands creation of developable land by reclaiming the harbor and terracing hillslopes. The vertical faces between adjoining hillslope-platforms are often stabilized by stone retaining walls. Such artificial cliffs embedded in the urban matrix, as a habitat analogue of rocky cliffs, have been colonized by spontaneous-ruderal vegetation. Detailed field assessment of 289 walls with 793 trees permitted in-depth analysis of this unique tropical urban ecology to inform conservation. The 28 stonewall tree species, mainly native, are dominated by six keystone and companion Ficus (Moraceae) species. They can develop into large cliff hangers > 20 m height on the apparently precarious and inhospitable walls. The many joints between masonry blocks provide opportunities for lodging and germination of seeds brought by frugivorous birds and bats. The aft-soil behind walls provides catchment for normal root functions. Beginning as pioneers and persisting as climax members, they short-circuit the seral processes. Wall-gripping capability as large epilithic woody hemi-epiphytes is due to the strangler-fig habit, an evolutionary trait that originated in the tropical forest. The polymorphic roots with morphological plasticity and self-grafting ability, and their multiple modes of interactions with wall niches, account for firm attachment on the vertical habitat and exploration of proximal soils. A model of strangler-fig growth on stone walls serving as surrogate host tree is developed. The diverse and versatile rooting modes are the basis to sustain strangler-fig wall conditions to permit continuation of strangler-fig habit. Such unique nature-in-city and natural-cum-cultural gems deserve conservation as urban ecological heritage. © 2013 Springer Science+Business Media New York.

Jo W.K.,University of Hong Kong | Law A.C.K.,University of Hong Kong | Chung S.K.,University of Hong Kong
Molecular Psychiatry | Year: 2014

Alzheimer's disease (AD) and vascular dementia are the major causes of cognitive disorders worldwide. They are characterized by cognitive impairments along with neuropsychiatric symptoms, and that their pathogeneses show overlapping multifactorial mechanisms. Although AD has long been considered the most common cause of dementia, individuals afflicted with AD commonly exhibit cerebral vascular abnormalities. The concept of mixed dementia has emerged to more clearly identify patients with neurodegenerative phenomena exhibiting both AD and cerebral vascular pathologies - vascular damage along with β-amyloid (Aβ)-associated neurotoxicity and τ-hyperphosphorylation. Cognitive impairment has long been commonly explained through a 'neuro-centric' perspective, but emerging evidence has shed light over the important roles that neurovascular unit dysfunction could have in neuronal death. Moreover, accumulating data have been demonstrating astrocytes being the essential cell type in maintaining proper central nervous system functioning. In relation to dementia, the roles of astrocytes in Aβ deposition and clearance are unclear. This article emphasizes the multiple events triggered by ischemia and the cytotoxicity exerted by Aβ either alone or in association with endothelin-1 and receptor for advanced glycation end products, thereby leading to neurodegeneration in an 'astroglio-centric' perspective. © 2014 Macmillan Publishers Limited All rights reserved.

Ellobody E.,Tanta University | Young B.,University of Hong Kong
Journal of Constructional Steel Research | Year: 2011

This paper investigates the behaviour of pin-ended axially loaded concrete encased steel composite columns. A nonlinear 3-D finite element model was developed to analyse the inelastic behaviour of steel, concrete, longitudinal and transverse reinforcement bars as well as the effect of concrete confinement of the concrete encased steel composite columns. The interface between the steel section and concrete, the longitudinal and transverse reinforcement bars, and the reinforcement bars and concrete were also considered that allowed the bond behaviour to be modeled and the different components to retain their profile during the deformation of the column. Furthermore, the initial overall (out-of-straightness) geometric imperfection was carefully incorporated in the model. The finite element model has been validated against published experimental results. The main objective of the study was to understand the structural response and modes of failure of the columns and to assess the composite column strengths against current design codes. The study covered slender, non-slender, stub and long concrete encased steel composite columns. The concrete strengths varied from normal to high strength (20110 MPa). The steel section yield stresses also varied from normal to high strength (275690 MPa). Furthermore, the variables that influence the composite column behaviour and strength comprising different slenderness ratios, concrete strength and steel yield stress were investigated in a parametric study. It is shown that the increase in structural steel strength has a small effect on the composite column strength for the columns having higher relative slenderness ratios due to the flexural buckling failure mode. The composite column strengths obtained from the finite element analysis were compared with the design strengths calculated using the American Institute for Steel Construction AISC and Eurocode 4 for composite columns. Generally, it is shown that the EC 4 accurately predicted the design strength for the concrete encased steel composite columns having a concrete cylinder strength of 30 MPa and structural steel yield stresses of 275 and 460 MPa, which are in the limits of the code, which otherwise, was generally conservative. The AISC predictions were quite conservative for all the concrete encased steel composite columns. © 2010 Elsevier Ltd. All rights reserved.

Xiao S.,University of Hong Kong | Chye M.-L.,University of Hong Kong
Plant Physiology | Year: 2011

ACBP3 is one of six Arabidopsis (Arabidopsis thaliana) genes, designated ACBP1 to ACBP6, that encode acyl-coenzyme A (CoA)-binding proteins (ACBPs). These ACBPs bind long-chain acyl-CoA esters and phospholipids and are involved in diverse cellular functions, including acyl-CoA homeostasis, development, and stress tolerance. Recombinant ACBP3 binds polyunsaturated acyl-CoA esters and phospholipids in vitro. Here, we show that ACBP3 plays a role in the plant defense response to the bacterial pathogen Pseudomonas syringae pv tomato DC3000. ACBP3 mRNA was up-regulated upon pathogen infection and treatments using pathogen elicitors and defense-related phytohormones. Transgenic Arabidopsis ACBP3 overexpressors (ACBP3-OEs) showed constitutive expression of pathogenesis-related genes (PR1, PR2, and PR5), cell death, and hydrogen peroxide accumulation in leaves. Consequently, ACBP3-OEs displayed enhanced resistance to the bacterial pathogen P. syringae DC3000. In contrast, the acbp3 T-DNA insertional mutant was more susceptible and exhibited lower PR gene transcript levels upon infection. Using the ACBP3 OE-1 line in combination with nonexpressor of PR genes1 (npr1-5) or coronatine-insensitive1 (coi1-2), we concluded that the enhanced PR gene expression and P. syringae DC3000 resistance in the ACBP3-OEs are dependent on the NPR1-mediated, but not the COI1-mediated, signaling pathway. Given that ACBP3-OEs showed greater susceptibility to infection by the necrotrophic fungus Botrytis cinerea while the acbp3 mutant was less susceptible, we suggest that ACBP3 plays a role in the plant defense response against biotrophic pathogens that is distinct from necrotrophic pathogens. ACBP3 function in plant defense was supported further by bioinformatics data showing up-regulation of many biotic and abiotic stress-related genes in ACBP3 OE-1 in comparison with the wild type. © 2011 American Society of Plant Biologists.

Liang Z.,Chinese University of Hong Kong | Tang Q.,Chinese University of Hong Kong | Xu J.,Chinese University of Hong Kong | Miao Q.,Chinese University of Hong Kong | Miao Q.,University of Hong Kong
Advanced Materials | Year: 2011

An exploratory study on a group of silylethynylated N-heteropentacenes as soluble and stable organic semiconductors is presented. An interesting finding is that a silylethynylated N-heteropentacene can function as a p-type, n-type, or ambipolar organic semiconductor depending on the structure of its π-backbone. The tetraazapentacene derivative is one of the best performing n-type organic semiconductors with an electron mobility of up to 3.3 cm 2 V-1 s-1. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

La Grange A.,City University of Hong Kong | Pretorius F.,University of Hong Kong
Urban Studies | Year: 2016

The specificity of Hong Kong’s gentrification trajectory reflects its urban morphology, political institutions, and social and economic structure. While continuously renewing itself economically, much of the city’s inner urban area building stock is old and functionally obsolete, whilst nevertheless providing affordable, well-located housing for lower-income and disadvantaged groups and small-scale commercial clusters. Constrained redevelopment is not the result of economic decline but rather of formidable frictions that make land assembly and vacant possession of buildings difficult. Hong Kong’s executive-led, quasi democratic government articulates with the public ownership of land and its management through the leasehold system, and leads inner-city redevelopment through the Urban Renewal Authority (URA) supported by various institutional and statutory arrangements. (Re)development is favoured because it generates significant state revenue from physical and economic intensification of sites. Although gentrification is not an agenda of the URA, it is a significant outcome of its redevelopment activities. © 2014, © Urban Studies Journal Limited 2014.

Zhang X.-Q.,University of Hong Kong | Leung G.K.-K.,University of Hong Kong
Neurochemistry International | Year: 2014

Long non-coding RNAs (lncRNAs) are a new class of non-coding gene regulators. But unlike their smaller counterparts, microRNAs, relatively less is known about the roles and functions of lncRNAs. Current evidence suggests that lncRNAs may play important roles in a wide range of biological processes in human cancers, including glioma. By acting as oncogenes or tumor suppressors, lncRNAs may contribute to glioma initiation, progression and other malignant phenotypes. Their expression profiles may also have important clinical implications in glioma subclassification and patients' prognostication. Here, we review current evidence related to the functional roles of lncRNAs in glioma. We will discuss the aberrant lncRNA expression signatures associated with glioma initiation and progression, as well as the potential mechanisms underlying lncRNA dysregulation. We also discuss the functional roles of lncRNAs in glioma biological behavior. Finally, the potentials and prospects of employing lncRNAs as novel biomarkers and therapeutic targets for glioma clinical practice will also be addressed. © 2014 Elsevier Ltd. All rights reserved.

Cheung V.Y.T.,University of Hong Kong
Journal of Minimally Invasive Gynecology | Year: 2015

The objective of this study was to determine the outcome of using ultrasound-guided local methotrexate injection as the first-line treatment of cesarean scar pregnancy (CSP). A literature review was performed on all eligible reports using this modality as the first-line treatment of CSP. Relevant publications were obtained from the PubMed electronic database from inception to December 2014. Ninety-six cases from 95 women reported in 17 articles were reviewed. The success rate was 73.9% after a single local methotrexate injection. An accumulated success rate of 88.5% could be achieved after additional local or intramuscular methotrexate administration. Eleven cases (11.5%) failed methotrexate treatment and required surgical interventions. Except for women with serum human chorionic gonadotropin levels higher than 100 000 IU/L, ultrasound-guided local methotrexate injection could be considered as a first-line treatment modality for CSP. © 2015 AAGL.

Cheung Y.-F.,University of Hong Kong
Korean Circulation Journal | Year: 2010

Arterial stiffness describes the rigidity of the arterial wall. Its significance owes to its relationship with the pulsatile afterload presented to the left ventricle and its implications on ventricular-arterial coupling. In adults, the contention that arterial stiffness as a marker and risk factor for cardiovascular morbidity and mortality is gaining support. Noninvasive methods have increasingly been adopted in both the research and clinical arena to determine local, segmental, and systemic arterial stiffness in the young. With adoption of these noninvasive techniques for use in children and adolescents, the phenomenon and significance of arterial stiffening in the young is beginning to be unveiled. The list of childhood factors and conditions found to be associated with arterial stiffening has expanded rapidly over the last decade; these include traditional cardiovascular risk factors, prenatal growth restriction, vasculitides, vasculopathies associated with various syndromes, congenital heart disease, and several systemic diseases. The findings of arterial stiffening have functional implications on energetic efficiency, structure, and function of the left ventricle. Early identification of arterial dysfunction in childhood may provide a window for early intervention, although longitudinal studies are required to determine whether improvement of arterial function in normal and at-risk paediatric populations will be translated into clinical benefits. Copyright ©2010 The Korean Society of Cardiology.

Szeto W.Y.,University of Hong Kong
Transportation Research Part C: Emerging Technologies | Year: 2011

Traditionally, game-theoretic approaches to measuring transport network reliability have relied on the outcome of a game played between on the one hand users who seek minimum cost routes, and on the other hand, one or more evil entities or demons that seek to maximize the total expected network cost to the users by damaging links in the network. As the demons are assumed to be non-cooperative, this approach has been criticized that it cannot produce the worst-case solution for reliability analysis, contradicting the original purpose of adopting game-theoretic approaches. In this paper, two cooperative game formulations, the Stackelberg-Nash formulation and the partial-cooperative Nash formulation, are proposed to determine travel cost reliability. Their relationships are analyzed and their properties are examined. This paper also investigates under what condition(s) the classical non-cooperative demon behavior can lead to the worst-case solution. Numerical studies are provided to demonstrate: (i) the effects of the number of coalitions formed by demons on total network expected cost and network/Origin-Destination (OD) travel cost reliability; (ii) the paradoxical phenomenon that if one adds a road to a network then all the travelers may be worse off in terms of expected network travel cost and/or network travel cost reliability, and (iii) the possibility of the classical game-theoretic approach of overestimating network/OD travel cost reliability. © 2010 Elsevier Ltd.

Cheng C.Y.Y.,University of Hong Kong | Chu J.Y.S.,University of Hong Kong | Chow B.K.C.,University of Hong Kong
Neuropsychopharmacology | Year: 2011

Secretin (Sct) is released into the circulation postprandially from the duodenal S-cells. The major functions of Sct originated from the gastrointestinal system are to delay gastric emptying, stimulate fluid secretion from pancreas and liver, and hence optimize the digestion process. In recent years, Sct and its receptor (Sctr) have been identified in discrete nuclei of the hypothalamus, including the paraventricular nucleus (PVN) and the arcuate nucleus (Arc). These nuclei are the primary brain sites that are engaged in regulating body energy homeostasis, thus providing anatomical evidence to support a functional role of Sct in appetite control. In this study, the effect of Sct on feeding behavior was investigated using wild-type (wt), Sct -/-, and secretin receptor-deficient (Sctr -/-) mice. We found that both central and peripheral administration of Sct could induce Fos expression in the PVN and Arc, suggesting the activation of hypothalamic feeding centers by this peptide. Consistent with this notion, Sct was found to increase thyrotropin-releasing hormone and melanocortin-4 receptor (Mc4r) transcripts in the PVN, and augment proopiomelanocortin, but reduces agouti-related protein mRNA expression in the Arc. Injection of Sct was able to suppress food intake in wt mice, but not in Sctr -/- mice, and that this effect was abolished upon pretreatment with SHU9119, an antagonist for Mc4r. In summary, our data suggest for the first time that Sct is an anorectic peptide, and that this function is mediated by the melanocortin system. © 2011 American College of Neuropsychopharmacology. All rights reserved.

Wu Y.-C.,University of Hong Kong | Chaudhari Q.,Iqra University | Serpedin E.,Texas A&M University
IEEE Signal Processing Magazine | Year: 2011

Clock synchronization is a critical component in the operation of wireless sensor networks (WSNs), as it provides a common time frame to different nodes. It supports functions such as fusing voice and video data from different sensor nodes, time-based channel sharing, and coordinated sleep wake-up node scheduling mechanisms. Early studies on clock synchronization for WSNs mainly focused on protocol design. However, the clock synchronization problem is inherently related to parameter estimation, and, recently, studies on clock synchronization began to emerge by adopting a statistical signal processing framework. In this article, a survey on the latest advances in the field of clock synchronization of WSNs is provided by following a signal processing viewpoint. This article illustrates that many of the proposed clock synchronization protocols can be interpreted and their performance assessed using common statistical signal processing methods. It is also shown that advanced signal processing techniques enable the derivation of optimal clock synchronization algorithms under challenging scenarios. © 2010 IEEE.

Li S.Y.W.,University of Hong Kong | Magrabi F.,University of New South Wales | Coiera E.,University of New South Wales
Journal of the American Medical Informatics Association | Year: 2012

Objective: To understand the complex effects of interruption in healthcare. Materials and methods: As interruptions have been well studied in other domains, the authors undertook a systematic review of experimental studies in psychology and humanecomputer interaction to identify the task types and variables influencing interruption effects. Results: 63 studies were identified from 812 articles retrieved by systematic searches. On the basis of interruption profiles for generic tasks, it was found that clinical tasks can be distinguished into three broad types: procedural, problem-solving, and decision-making. Twelve experimental variables that influence interruption effects were identified. Of these, six are the most important, based on the number of studies and because of their centrality to interruption effects, including working memory load, interruption position, similarity, modality, handling strategies, and practice effect. The variables are explained by three main theoretical frameworks: the activation-based goal memory model, prospective memory, and multiple resource theory. Discussion: This review provides a useful starting point for a more comprehensive examination of interruptions potentially leading to an improved understanding about the impact of this phenomenon on patient safety and task efficiency. The authors provide some recommendations to counter interruption effects. Conclusion: The effects of interruption are the outcome of a complex set of variables and should not be considered as uniformly predictable or bad. The task types, variables, and theories should help us better to identify which clinical tasks and contexts are most susceptible and assist in the design of information systems and processes that are resilient to interruption.

Chan W.Y.,University of Hong Kong | Chan H.P.,University of Hong Kong
Optics Express | Year: 2014

A reconfigurable two-mode mux/demux device in planar waveguide was proposed. The simulated mux/demux extinction ratio was = 35 dB with = 0.4 dB excess loss. The device was realized in polymer materials using the thermo-optic effect. It was characterized via a tunable laser source at 1550 nm. Its mux/demux performance in both routes was demonstrated and compared with the theoretical prediction. The device is easy to implement and has applications in future multimode optical communication systems to further extend transmission capacity.©2013 Optical Society of America.

Limited improvement in long term survival of lung cancer patients has been achieved by conventional chemotherapy or targeted therapy. To explore the potentials of tumor initiating cells (TIC)-directed therapy, it is essential to identify the cell targets and understand their maintenance mechanisms. We have analyzed the performance of ALDH/CD44 co-expression as TIC markers and treatment targets of lung cancer using well-validated in vitro and in vivo analyses in multiple established and patient-derived lung cancer cells. The ALDH(hi)CD44(hi) subset showed the highest enhancement of stem cell phenotypic properties compared to ALDH(hi)CD44(lo), ALDH(lo)CD44(hi), ALDH(lo)CD44(lo) cells and unsorted controls. They showed higher invasion capacities, pluripotency genes and epithelial-mesenchymal transition transcription factors expression, lower intercellular adhesion protein expression and higher G2/M phase cell cycle fraction. In immunosuppressed mice, the ALDH(hi)CD44(hi)xenografts showed the highest tumor induction frequency, serial transplantability, shortest latency, largest volume and highest growth rates. Inhibition of sonic Hedgehog and Notch developmental pathways reduced ALDH+CD44+ compartment. Chemotherapy and targeted therapy resulted in higher AALDH(hi)CD44(hi) subset viability and ALDH(lo)CD44(lo) subset apoptosis fraction. ALDH inhibition and CD44 knockdown led to reduced stemness gene expression and sensitization to drug treatment. In accordance, clinical lung cancers containing a higher abundance of ALDH and CD44-coexpressing cells was associated with lower recurrence-free survival. Together, results suggested theALDH(hi)CD44(hi)compartment was the cellular mediator of tumorigenicity and drug resistance. Further investigation of the regulatory mechanisms underlying ALDH(hi)CD44(hi)TIC maintenance would be beneficial for the development of long term lung cancer control.

Kuah-Pearce K.E.,University of Hong Kong
Anthropology and Medicine | Year: 2014

This paper will explore the social engagement of Buddhists through their active voluntary works - works that result in the development of a religious philanthropic culture. Through three case examples, this paper will examine how the sangha and individual Buddhists understand social suffering and compassion and attempt to integrate their understanding of Buddhist virtues and values in their daily life where the performance of voluntary works is seen as Buddhist spiritualism. In this process, the individuals seek to understand the key principles of Buddhism that are of direct relevance to their daily existence and their quest to be a compassionate self. Foremost are two notions of yebao (karma) and gan-en (gratitude) and how through compassionate practices and gratitude for those who accepted compassionate acts, they would be rewarded with good karma. Here, pursuing compassionate acts and the alleviation of social suffering is the pursuit of this-worldly spiritualism. © 2014 Taylor & Francis.

Sauret A.,University of Hong Kong | Sauret A.,Aix - Marseille University | Shum H.C.,University of Hong Kong
Applied Physics Letters | Year: 2012

We report an easy-to-implement method that allows the direct generation of water-in-water (w/w) single emulsions. The method relies on direct perturbation of the pressure that drives the flow of the dispersed phase of the emulsions. The resultant inner jet is induced to break up into droplets due to the growth of the perturbation through Rayleigh-Plateau instability [L. Rayleigh, Proc. R. Soc. London 29, 71-97 (1879)]; this leads to the formation of monodisperse droplets. By implementing this method on a modified microfluidic device, we directly generate water-in-water-in-water (w/w/w) double emulsions with good control over the size and the number of encapsulated droplets. Our approach suggests a route to apply droplet-based microfluidics to completely water-based systems. © 2012 American Institute of Physics.

Jiang Y.C.,University of Hong Kong | Gao J.,University of Hong Kong
Applied Physics Letters | Year: 2012

Heterostructures of Co-doped amorphous carbon (Co-C)/silicon were fabricated by growing Co-C films on n-type Si substrates using pulsed laser deposition. The heterostructures exhibited a positive colossal magnetoresistance (CMR) effect over a temperature range of 55-240 K. The magnetoresistance (MR) for the reverse bias voltage reached around 270 at 5 T, whereas the MR under a forward bias was 7 only. Besides, the transmission electron microscopy results demonstrate that Co atoms tended to be aggregated at Co-C/Si interface. The Co aggregation in the interface may be a possible origin of the positive CMR effect. © 2012 American Institute of Physics.

Chan J.Y.W.,University of Hong Kong
Current Oncology Reports | Year: 2015

Nasopharyngeal carcinoma is a unique tumour which is endemic in southern China including Hong Kong. Whilst the treatment results for the primary cancer has been encouraging, management of recurrent tumours has been challenging. Compared to other surgical approaches, the maxillary swing operation provides wide access to the bilateral nasopharynx and the ipsilateral parapharyngeal space, allowing resection of tumours with adequate margins. Among the 312 patients who had received salvage nasopharyngectomy via the maxillary swing approach, the chance of achieving microscopically clear resection margins was 79.5 %. The overall local recurrence rate after surgery was 13.1 %. Multivariate analysis showed that resection margin status, synchronous nodal recurrence and cavernous sinus invasion were independent prognostic factors for overall survival. For small tumours located in the posterior wall, endoscopic resection, or more recently, the transoral robotic (TORS)-assisted approach, can be performed. Every effort should be made to ensure microscopic clearance of disease as well as to minimize the potential complications of surgery that may adversely affect the subsequent quality of life. © 2015, Springer Science+Business Media New York.

Li B.,University of Hong Kong | Zhang T.,University of Hong Kong
Water Research | Year: 2013

The chlorination behaviours of 12 antibiotics belonging to six classes at environmentally relevant concentrations were systematically examined under typical conditions relevant to municipal wastewater chlorination. Cefotaxime, cefalexin, ampicillin and tetracycline were completely removed under all three initial free chlorine dosages (5mg/L, 10mg/L, and 15mg/L). The removal efficiencies of sulphamethoxazole, sulphadiazine, roxithromycin, anhydro-erythromycin, ofloxacin, and trimethoprim were closely correlated to the residual free chlorine concentration, and no further significant mass removal was observed after the residual free chlorine concentration decreased to less than ~0.75mg/L. Ammonia plays a critical role during chlorination because of its competition with antibiotics for free chlorine to form combined chlorine, which reacts slowly with these antibiotics. Except for norfloxacin and ciprofloxacin, the removal behaviours of the 10 other target antibiotics under ammonia nitrogen concentrations ranging from 2 to 15mg/L were characterised by a rapid initial removal rate upon contact with free chlorine during the first 5s-1min (depending on the specific antibiotic and ammonia nitrogen concentration) and then a much slower removal rate. Free chlorine was responsible for the reaction with antibiotics during the rapid stage (first 5s-1min), whereas combined chlorine reacted with antibiotics in the subsequent slow stage. Combined chlorine can remove norfloxacin and ciprofloxacin at a relatively faster rate. The presence of suspended solids at 30mg/L slightly decreased the antibiotic removal rate. The kinetic rate constants decreased by 2.1-13.9%, while the half-lives increased by 2.0-15.0% compared to those of a 0mg/L suspended solid for the target antibiotics. © 2013 Elsevier Ltd.

Cerin E.,University of Hong Kong
Mental Health and Physical Activity | Year: 2010

Objective: Knowledge of the mechanisms responsible for the effects of physical activity on aspects of mental health is limited. Appropriate experimental trials and statistical mediation analyses of experimental, quasi-experimental and observational studies can help shed light on these mechanisms. A critical overview of methods for mediation analyses is provided. Recommendations relevant to studies in the field of physical activity and mental health are made. Strategy: Main issues pertaining to the identification of mechanisms of influence (mediators) are discussed. Recommendations on appropriate methods of mediation analysis for cross-sectional and longitudinal data and ways of presenting findings from such analyses are provided. Finally, future directions in methods of mediation analyses are briefly outlined. Conclusions: There is a dearth of mediation studies in the field of physical activity and mental health, which explains why not much is known about the underlying mechanisms of influence. An array of experimental and statistical methods is available to those who wish to unravel how and why physical activity affects various aspects of mental health in diverse populations and circumstances. The correct use of, and presentation of findings from, methods of mediation analyses is vital for clarifying how mental health can be enhanced through participation in physical activity. © 2010 Elsevier Ltd. All rights reserved.

Li T.M.H.,University of Hong Kong | Wong P.W.C.,University of Hong Kong
Australian and New Zealand Journal of Psychiatry | Year: 2015

Objective: Acute and/or severe social withdrawal behavior among youth was seen as a culture-bound psychiatric syndrome in Japan, but more youth social withdrawal cases in different countries have been discovered recently. However, due to the lack of a formal definition and diagnostic tool for youth social withdrawal, cross-cultural observational and intervention studies are limited. We aimed to consolidate existing knowledge in order to understand youth social withdrawal from diverse perspectives and suggest different interventions for different trajectories of youth social withdrawal. Method: This review examined the current available scientific information on youth social withdrawal in the academic databases: ProQuest, ScienceDirect, Web of Science and PubMed. We included quantitative and qualitative studies of socially withdrawn youths published in English and academic peer-reviewed journals. Results: We synthesized the information into the following categories: (1) definitions of youth social withdrawal, (2) developmental theories, (3) factors associated with youth social withdrawal and (4) interventions for socially withdrawn youths. Accordingly, there are diverse and controversial definitions for youth social withdrawal. Studies of youth social withdrawal are based on models that lead to quite different conclusions. Researchers with an attachment perspective view youth social withdrawal as a negative phenomenon, whereas those who adopt Erikson?s developmental theory view it more positively as a process of seeking self-knowledge. Different interventions for socially withdrawn youths have been developed, mainly in Japan, but evidence-based practice is almost non-existent. Conclusion: We propose a theoretical framework that views youth social withdrawal as resulting from the interplay between psychological, social and behavioral factors. Future validation of the framework will help drive forward advances in theory and interventions for youth social withdrawal as an emerging issue in developed countries. © 2015 The Royal Australian and New Zealand College of Psychiatrists.

Lam M.P.S.,University of Hong Kong | Cheung B.M.Y.,University of Hong Kong
Expert Review of Clinical Pharmacology | Year: 2012

Although numerous initiatives and interventions have been developed to promote medication safety, medication incidents still remain an important cause of hospitalization. To avoid this, it is important for physicians to prescribe safely. To date, the Beers criteria have been the most widely used explicit criteria for assessing the appropriateness of medications in the elderly, but they do have limitations. The more recent STOPP/START criteria were developed in the hope of addressing the deficiencies observed in the Beers criteria. This article gives an overview of STOPP/START criteria and its applications, and reviews the studies that assessed medication appropriateness using STOPP/START and/or the Beers criteria. © 2012 Expert Reviews Ltd.

Wong C.K.H.,University of Hong Kong | Lang B.H.-H.,University of Hong Kong
Annals of Surgical Oncology | Year: 2014

Background: Although prophylactic central neck dissection (pCND) may reduce future locoregional recurrence after total thyroidectomy (TT) for low-risk papillary thyroid carcinoma (PTC), it is associated with a higher initial morbidity. We aimed to compare the long-term cost-effectiveness between TT with pCND (TT+pCND) and TT alone in the institution's perspective. Methods: Our case definition was a hypothetical cohort of 100,000 nonpregnant female patients aged 50 years with a 1.5-cm cN0 PTC within one lobe. A Markov decision tree model was constructed to compare the estimated cost-effectiveness between TT+pCND and TT alone after a 20-year period. Outcome probabilities, utilities, and costs were estimated from the literature. The threshold for cost-effectiveness was set at US$50,000 per quality-adjusted life year (QALY). Sensitivity and threshold analyses were used to examine model uncertainty. Results: Each patient who underwent TT+pCND instead of TT alone cost an extra US$34.52 but gained an additional 0.323 QALY. In fact, in the sensitivity analysis, TT+pCND became cost-effective 9 years after the initial operation. In the threshold analysis, none of the scenarios that could change this conclusion appeared clinically possible or likely. However, TT+pCND became cost-saving (i.e., less costly and more cost-effective) at 20 years if associated permanent vocal cord palsy was kept ≤1.37 %, permanent hypoparathyroidism was ≤1.20 %, and/or postoperative radioiodine ablation use was ≤73.64 %. Conclusions: In the institution's perspective, routine pCND for low-risk PTC began to become cost-effective 9 years after initial surgery and became cost-saving at 20 years if postoperative radioiodine use and/or permanent surgical complications were kept to a minimum. © 2013 Society of Surgical Oncology.

Wang L.,Northeastern University China | Yung N.H.C.,University of Hong Kong
IEEE Transactions on Intelligent Transportation Systems | Year: 2012

In this paper, the problem of human detection in crowded scenes is formulated as a maximum a posteriori problem, in which, given a set of candidates, predefined 3-D human shape models are matched with image evidence, provided by foreground extraction and probability of boundary, to estimate the human configuration. The optimal solution is obtained by decomposing the mutually related candidates into unoccluded and occluded ones in each iteration according to a graph description of the candidate relations and then only matching models for the unoccluded candidates. A candidate validation and rejection process based on minimum description length and local occlusion reasoning is carried out after each iteration of model matching. The advantage of the proposed optimization procedure is that its computational cost is much smaller than that of global optimization methods, while its performance is comparable to them. The proposed method achieves a detection rate of about 2% higher on a subset of images of the Caviar data set than the best result reported by previous works. We also demonstrate the performance of the proposed method using another challenging data set. © 2011 IEEE.

Tao X.,City University of Hong Kong | Hui S.Y.R.,University of Hong Kong | Hui S.Y.R.,Imperial College London
IEEE Transactions on Industrial Electronics | Year: 2012

This paper presents a dynamic photoelectrothermal theory for light-emitting diode (LED) systems. In addition to photometric, electrical, and thermal aspects, this theory incorporates the time domain into the generalized equations. A dynamic model for a general LED system is developed for system analysis. This theory highlights the fact that the luminous output of an LED system will decrease with time from the initial operation to the steady state due to the rising temperature of the heat sink and the LED devices. The essential thermal time constants involved in the LED systems are explained. The time factor is critical in understanding how much the luminous output will decrease with time and is essential to the optimal designs of the LED systems that are operated continuously (e.g., general lighting) or momentarily (e.g., traffic lights). Experiments on several LED systems at different time frames have been conducted, and the practical measurements confirm the validity of this theory. © 2011 IEEE.

Gautam A.,Nanyang Technological University | Chu Y.-C.,University of Hong Kong | Soh Y.C.,Nanyang Technological University
IEEE Transactions on Automatic Control | Year: 2012

This paper deals with the problem of reducing the online computational complexity of receding horizon control (RHC) algorithms for a class of linear systems with a polytopic system description and with bounded additive disturbances. We explore a class of admissible polytopic controller dynamics involving a disturbance feedforward term for a dynamic policy which ensures reduced conservativeness and also offers a way to significantly simplify the online computations by allowing the controller dynamics to be optimized offline. Moreover, for a deterministically time-varying system with additive disturbances, we explore the use of the proposed dynamic policy as the terminal control policy appended to a standard finite-horizon disturbance-based RHC policy. We also present results on the stability of the system under the RHC schemes based on the proposed policy, in the context of both the nominal and the (H ∞-based) minmax cost minimizations. Results of simulation studies that illustrate the effective performance and the computational efficiency of the proposed control schemes are included. © 2012 IEEE.

Jim C.Y.,University of Hong Kong
Landscape and Urban Planning | Year: 2015

Many cities have inadequate green infrastructures and cannot benefit from ecosystem services brought by greenspaces. Global warming and urban heat island (UHI) effect impose a dual warming impact on cities, especially compact ones. Green roofs offer a plausible solution for climate adaptation. In compact humid-tropical Hong Kong, two green-roof and a control bare-roof plots were installed on a high-rise building. Precision sensors were installed along a holistic vertical temperature profile extending from outdoor air to roof surface, green-roof material layers, and indoor ceiling and air. Three apartments under the plots were kept vacant to monitor air-conditioning energy consumption. The comprehensive-systematic data allowed in-depth analysis of thermal performance of vegetation (Sedum and Perennial Peanut) and weather (sunny, cloudy and rainy) in summer. Intense solar radiation at Control plot triggered significant material heating, which in turn warmed near-ground air to intensify UHI effect and indoor space to lift energy consumption. Sedum plot with incomplete plant cover, sluggish transpiration and limited substrate moisture storage had feeble evapotranspiration cooling. The warmed roof passed heat to near-ground air and subsurface layers to impose a small indoor cooling load. Peanut plot with high transpiration rate can significantly cool foliage surface and near-ground air to ameliorate UHI. Its high moisture-holding capacity, however, can generate an appreciable heat-sink to push heat downwards and increase indoor cooling load. Practical hints on green roof design and management were distilled from the findings for application in Hong Kong and beyond and to contribute to climate-resilient cities. © 2015 Elsevier B.V.

Jim C.Y.,University of Hong Kong
Landscape and Urban Planning | Year: 2015

Vertical greening can contribute to urban green infrastructure, urban heat-island amelioration and climate adaptation. Tropical greenwall practice, hindered by inadequate scientific knowledge and experience, can benefit from objective assessment of species performance and growth deficiency. Comprehensive survey of critical climber-plant traits shortlisted 20 potentially suitable species. A climber-selection matrix was established to facilitate species selection and greenwall design. Perennial woody climbers with ornamental flower or foliage and biological potential to reach 13-m height were preferred. They represented two attachment modes, namely mesh-climber and concrete-(bare-wall)climber groups. A field study was designed to monitor their growth from seedlings in experimental plots. Growth conditions were optimized by providing high-quality soil mix and irrigation. The 32-month study period included three active-growing seasons with two interspersed slow-growing seasons. Field assessment methods were developed to acquire systematic data on plant performance indicators and deficiency symptoms. Key attributes were selected to compute climber performance index (CPI) and climber deficiency index (CDI) as synoptic representation of greenwall-application suitability. Mesh-climbers performed much better than concrete-climbers across all key performance indicators, and with notably better CPI. They demonstrated faster establishment and growth rates and more ornamental flowers. The two groups had similar CDI mainly due to insufficient foliage density and foliage loss. For mesh-climbers, Quisqualis indica, Wisteria sinensis and Lonicera japonica had excellent performance, and the remaining species were good to fair. For concrete-climbers, only Parthenocissus dalzielii was rated good and Campsis grandiflora fair, with the rest poor to very poor. © 2015 Elsevier B.V..

OBJECTIVES:Hepatitis B core-related antigen (HBcrAg) is a novel serum marker that correlates with intrahepatic hepatitis B virus (HBV) activity. Its association with HBV reactivation in hepatitis B surface antigen (HBsAg)-negative antibody to hepatitis B core antigen (anti-HBc)-positive patients undergoing high-risk immunosuppressive therapy is undefined.METHODS:HBcrAg was measured in HBsAg-negative, anti-HBc-positive Asian patients with undetectable HBV DNA, who participated in two prospective studies investigating HBV reactivation during rituximab-containing chemotherapy and allogeneic hematopoietic stem cell transplantation (HSCT). Patients were monitored every 4 weeks for up to 2 years, with entecavir started when HBV reactivation, defined as HBV DNA ≥10 IU ml-1, developed.RESULTS:One hundred and twenty-four HBsAg-negative, anti-HBc-positive patients (rituximab, N=62; allogeneic HSCT, N=62) with a median follow-up of 64 weeks (range: 4–104 weeks) were studied. HBV reactivation occurred in 31 patients, with a 2-year cumulative reactivation rate of 40.4%. Serum HBcrAg was detected in 43 (34.7%) patients. Baseline HBcrAg positivity was significantly associated with HBV reactivation (P=0.004, hazard ratio (HR): 2.94, 95% confidence interval (95% CI): 1.43–6.07). HBcrAg-positive patients had a significantly higher 2-year HBV reactivation rate than HBcrAg-negative patients (71.8 vs. 31%, P=0.002). In the rituximab cohort, the HRs for positive HBcrAg and negative antibody to HBsAg for HBV reactivation were 3.65 and 2.84, respectively (P=0.011, 95% CI: 1.35–9.86 and P=0.032, 95% CI: 1.10–7.37, respectively).CONCLUSIONS:Serum HBcrAg positivity is a significant risk factor of HBV reactivation in HBsAg-negative, anti-HBc-positive patients undergoing high-risk immunosuppressive therapy and can potentially have a role in identifying patients who will best benefit from prophylactic nucleoside analogue treatment.Am J Gastroenterol advance online publication, 20 September 2016; doi:10.1038/ajg.2016.436. © 2016 American College of Gastroenterology

Chen M.,University of Hong Kong | Chan K.L.,University of Hong Kong
Trauma, Violence, and Abuse | Year: 2016

The objective of this study is to evaluate the effectiveness of parenting programs in reducing child maltreatment and modifying associated factors as well as to examine the moderator variables that are linked to program effects. For this meta-analysis, we searched nine electronic databases to identify randomized controlled trials published before September 2013. The effect sizes of various outcomes at different time points were computed. From the 3,578 studies identified, we selected 37 studies for further analysis. The total random effect size was 0.296. Our results showed that parenting programs successfully reduced substantiated and self-reported child maltreatment reports and reduced the potential for child maltreatment. The programs also reduced risk factors and enhanced protective factors associated with child maltreatment. However, the effects of the parenting programs on reducing parental depression and stress were limited. Parenting programs produced positive effects in low-, middle-, and high-income countries and were effective in reducing child maltreatment when applied as primary, secondary, or tertiary child maltreatment intervention. In conclusion, parenting programs are effective public health approaches to reduce child maltreatment. The evidence-based service of parenting programs could be widely adopted in future practice. © 2015, The Author(s) 2015.

Kong T.S.K.,University of Hong Kong
British Journal of Criminology | Year: 2016

Commercial sex is a risky business and men who buy sex engage in a form of voluntary risky behaviour. Using Stephen Lyng's notion of edgework, this qualitative study examines Hong Kong men who buy sex in Hong Kong/China and argues that these men's engagement can be understood as a form of leisure edgework which balances risk and pleasure by negotiating the boundary between order and chaos. This article concludes that men buying sex can be seen as a form of resistance to normative companionate sexuality and the skills they exercise are key cultural principles needed in late-modern society. Edgework therefore plays an important role in modern intimacy, especially in shaping masculinity and men's sexual scripts. © 2015 The Author 2015. Published by Oxford University Press on behalf of the Centre for Crime and Justice Studies (ISTD). All rights reserved.

Zhang Q.,University of Hong Kong | Li K.H.,University of Hong Kong | Choi H.W.,University of Hong Kong
Applied Physics Letters | Year: 2012

Close-packed micro-lenses with dimensions of the order of wavelength have been integrated onto the indium-tin-oxide (ITO) layer of GaN light-emitting diodes employing nanosphere lithography. The ITO lens arrays are transferred from a self-assembled silica nanosphere array by dry etching, leaving the semiconductor layer damage-free. An enhancement of up to 63.5% on optical output power from the lensed light-emitting diode (LED) has been observed. Lens-patterned LEDs are also found to exhibit reduced emission divergence. Three-dimensional finite-difference time-domain simulations performed for light extraction and emission characteristics are found to be consistent with the observed results. © 2012 American Institute of Physics.

Artificial turf can develop unusually high surface temperature on hot sunny days. Solar and terrestrial radiant energy regimes as key determinants of thermal performance deserve detailed investigation. This study evaluated six components of the radiant-energy environment of a natural turf (NT) and a contiguous artificial turf (AT) sports fields in Hong Kong: direct solar, reflected solar, net solar, sky thermal, ground thermal, and net thermal. Temperature was monitored at five positions: air at 150 cm, 50 cm and 15 cm height, turf surface, and substrate. The experiment included four replications, namely two summer sunny days, and two duplicated instrument sets at each turf site. The two sites reacted very differently to the same intense daily sum of solar radiation input of 23.70 MW m-2 with 9 h of bright sunshine (>120 W m-2), and daily sum of sky thermal radiation input of 38.59 MW m-2. The maximum direct solar radiation reached 976.1 W m-2 at 1245 h. NT albedo of 0.23 vis-à-vis AT of merely 0.073, and higher moisture content and specific heat of NT materials, presented critical differences. The hydrophobic and generally dry plastic (polyethylene) pile-fibers and black rubber-granule infill materials have low specific heat. Intense incoming shortwave and longwave radiation absorbed readily by AT materials raised turf surface temperature to 70.2 °C and substrate 69.3 °C, in comparison with <40 °C at NT. A cascading warming effect was triggered, beginning with low albedo, high net solar irradiance and low material specific heat, leading to heated AT materials, high ground-thermal radiation, and heat flux to near-ground air by conduction and convection. The ephemeral rainfall cooling confirmed ineffective cooling by irrigation. Athletes are immersed in an anomalously intense and omnidirectional radiant-energy and sensible-heat ambience. The heat-stress health implications of AT for athletes in hot summer afternoon call for preventive-precautionary measures and re-assessment of NT-to-AT decisions. © 2016 Elsevier Ltd.

Li R.X.,University of Hong Kong | Tang S.C.W.,University of Hong Kong
Frontiers in Physiology | Year: 2015

Renal fibrosis is final common pathway of end stage renal disease. Irrespective of the primary cause, renal fibrogenesis is a dynamic process which involves a large network of cellular and molecular interaction, including pro-inflammatory cell infiltration and activation, matrix-producing cell accumulation and activation, and secretion of profibrogenic factors that modulate extracellular matrix (ECM) formation and cell-cell interaction. Bone morphogenetic protein-7 is a protein of the TGF-β super family and increasingly regarded as a counteracting molecule against TGF-β. A large variety of evidence shows an anti-fibrotic role of BMP-7 in chronic kidney disease, and this effect is largely mediated via counterbalancing the profibrotic effect of TGF-β. Besides, BMP-7 reduced ECM formation by inactivating matrix-producing cells and promoting mesenchymal-to-epithelial transition (MET). BMP-7 also increased ECM degradation. Despite these observations, the anti-fibrotic effect of BMP-7 is still controversial such that fine regulation of BMP-7 expression in vivo might be a great challenge for its ultimate clinical application. © 2015 Li and Tang.

Huang H.,University of Hong Kong | Leung D.Y.C.,University of Hong Kong
Journal of Catalysis | Year: 2011

A series of highly active supported Pt catalysts, developed by sodium borohydride reduction under mild preparation conditions, were used to eliminate indoor formaldehyde (HCHO) at ambient temperature. The influences of oxidation state, support and size of Pt particles, and the operating parameters were investigated. The reduced Pt nanoparticles with different supports are highly active for catalytic oxidation of HCHO. For example, nearly 100% HCHO conversion was obtained on the reduced Pt/TiO2 catalysts (denoted as Pt-TiO2) even with 0.1% Pt loading while it was less than 25% on the oxidized ones. Negatively charged metallic Pt nanoparticles, which probably facilitate the electron transfer and formation of active oxygen, provide the active sites for HCHO oxidation. The turnover frequencies (TOFs) of HCHO oxidation on Pt nanoparticles with different supports are not sensitive to the reducibility of support but somewhat affected by the Pt particle sizes. A maximum TOF of 2.87 s-1 was obtained on the 1% Pt-MgO with Pt particle size of about 3 nm. The 0.1% Pt-TiO2 catalyst remained highly active and stable in humid air with a wide gas hourly space velocity range between 40,000 and 240,000 h-1 and initial HCHO concentration range between 5 and 30 ppm. © 2011 Elsevier Inc. All rights reserved.

Wang A.Y.M.,University of Hong Kong
Seminars in Nephrology | Year: 2011

The mortality of end-stage renal disease (ESRD) patients, including those receiving long-term peritoneal dialysis (PD), has remained unacceptably high owing to the prevalence of cardiovascular disease. It is well recognized that both traditional Framingham risk factors and kidney disease-related risk factors may contribute to the high prevalence of cardiovascular disease in these patients. Of the different risk factors, chronic inflammation frequently is observed in long-term PD patients. The causes of inflammation are usually complex and multifactorial, involving both dialysis-related and dialysis-unrelated factors. Inflammation is strongly associated with cardiovascular disease and malnutrition, and has been shown consistently to be a powerful predictor of mortality and adverse cardiovascular outcomes in PD patients. In this article we review the prevalence and potential causes of chronic inflammation in PD patients. More importantly, we provide emerging evidence that shows the serious consequences of chronic systemic inflammation in PD patients and the important contribution of inflammation to adverse clinical outcomes. © 2011 Elsevier Inc.

Zhang D.,University of Hong Kong | Xie F.,University of Hong Kong | Lin P.,University of Hong Kong | Choy W.C.H.,University of Hong Kong
ACS Nano | Year: 2013

While there are challenges in tuning the properties of graphene (surface wettability, work function alignment, and carrier transport) for realizing an efficient graphene cathode in organic solar cells (OSCs), we propose and demonstrate using an Al-TiO2 composite to modify single-layer graphene as an efficient cathode for OSCs. To unveil the contributions of the composite in addressing the aforementioned challenges, the evaporated aluminum nanoclusters in the composite benefit the graphene cathode by simultaneously achieving two roles of improving its surface wettability for subsequent TiO 2 deposition and reducing its work function to offer better energy alignment. To address challenges related to charge transport, solution-processed TiO2 with excellent electron transport can offer charge extraction enhancement to the graphene cathode, which is essential to efficient devices. However, it is a well-known issue for methods such as spin-coating to produce uniform films on the initially hydrophobic graphene, even with improved wettability. The undesirable morphology of TiO2 by such methods considerably inhibits its effectiveness in enhancing charge extraction. We propose a self-assembly method to deposit the solution-processed TiO2 on the Al-covered graphene for forming the Al-TiO2 composite. Compared with spin-coating, the self-assembly method is found to achieve more uniform coating on the graphene surface, with highly controllable thickness. Consequently, the graphene cathode modified with the Al-TiO2 composite in inverted OSCs gives rise to enhanced power conversion efficiency of 2.58%, which is 2-fold of the previously best reported efficiency (1.27%) for graphene cathode OSCs, reaching ∼75% performance of control devices using indium tin oxide. © 2013 American Chemical Society.

Lam V.Y.Y.,University of Hong Kong | Sadovy De Mitcheson Y.,University of Hong Kong
Fish and Fisheries | Year: 2011

Sharks fisheries have declined globally due to over- and unregulated fishing. As with many collapsed and unmonitored coastal fisheries, information is difficult to obtain, yet it is important to understand the historical changes determining population trends and evaluate the current status of sharks in order to conserve these vulnerable species. Here, we document for the first time the history and general condition of the shark fisheries of Southern China, specifically Hong Kong, and Guangdong, Fujian and Hainan Provinces. This study shows, through the use of historical literature and anecdotal accounts, including fisher interviews, that all known shark fisheries in the region collapsed between the 1970s and the 1990s. Of the 109 species present historically in the South China Sea, only 18 species were recorded in current market surveys, of which all were landed as bycatch and 65% were below the size of sexual maturity. Markets are dominated by smaller species, including the spadenose shark (Scoliodon laticaudus) and the whitespotted bambooshark (Chiloscyllium plagiosum). Marketed large shark species are almost all below the size of sexual maturation, evidence of growth overfishing and a factor in recruitment overfishing. Some species, like the whale (Rhincodon typus) and basking sharks (Cetorhinus maximus), are clearly vulnerable to local extinction without intervention. Given the inherent vulnerability of sharks and the overfished states of many sharks, there is clearly an urgent need to formulate impacting conservation and management plans for these rapidly declining species in a region that has the highest demand for shark products globally. © 2010 Blackwell Publishing Ltd.

Wang Y.,University of Hong Kong
Diabetes and Metabolism Journal | Year: 2014

Ageing is the most significant risk factor for a range of prevalent diseases, including cancer, cardiovascular disease, and diabetes. Accordingly, interventions are needed for delaying or preventing disorders associated with the ageing process, i.e., promotion of healthy ageing. Calorie restriction is the only nongenetic and the most robust approach to slow the process of ageing in evolutionarily divergent species, ranging from yeasts, worms, and flies to mammals. Although it has been known for more than 80 years that calorie restriction increases lifespan, a mechanistic understanding of this phenomenon remains elusive. Yeast silent information regulator 2 (Sir2), the founding member of the sirtuin family of protein deacetylases, and its mammalian homologue Sir2-like protein 1 (SIRT1), have been suggested to promote survival and longevity of organisms. SIRT1 exerts protective effects against a number of age-associated disorders. Caloric restriction increases both Sir2 and SIRT1 activity. This review focuses on the mechanistic insights between caloric restriction and Sir2/SIRT1 activation. A number of molecular links, including nicotinamide adenine dinucleotide, nicotinamide, biotin, and related metabolites, are suggested to be the most important conduits mediating caloric restriction- induced Sir2/SIRT1 activation and lifespan extension. © 2014 Korean Diabetes Association.

Wang C.-W.,University of Hong Kong | Chan C.L.W.,University of Hong Kong | Yip P.S.F.,University of Hong Kong
Social Psychiatry and Psychiatric Epidemiology | Year: 2014

Purposes: The aims of this study were: (1) to present the time trend of suicide rate among people aged 15 or above in China over the period 2002-2011 and (2) to examine the current profile of completed suicides during 2009-2011. Methods: Data on suicide rate in 2002-2011 were provided by the Chinese Ministry of Health (MOH). The trends of region-, gender-, and age-specific suicide rates were examined using Poisson regression models. The mean number of completed suicides for each cohort during 2009-2011 was calculated and a mean national suicide rate was estimated. Findings: The overall suicide rate decreased significantly over the past decade, but rates in young males and rural older adults did not reduce and in fact increased among older adults in both urban and rural areas towards the end of the study period. For 2009-2011, 44 % of all suicides occurred among those aged 65 or above and 79 % among rural residents. The estimated mean national suicide rate was 9.8 per 100,000 and was slightly higher for males than females. Conclusion: The benefits of economic growth, such as higher employment and more educational opportunities for the rural population in particular, may have contributed to the reduced suicide rate in China. However, the recent rapid changes in socioeconomic conditions could have increased stress levels and resulted in more suicides, especially among the elderly. Despite the significant reduction reported here, the latest figures suggest the declining trend is reversing. It will be important to continue monitoring the situation and to examine how urbanization and economic changes affect the well-being of 1.3 billion Chinese. © 2013 Springer-Verlag Berlin Heidelberg.

Zhou F.,Tongji University | Young B.,University of Hong Kong
Engineering Structures | Year: 2013

This paper reports a numerical investigation of cold-formed high strength stainless steel square and rectangular hollow sections subjected to web crippling at elevated temperatures. Finite element analysis was conducted on cold-formed high strength austenitic and duplex stainless steel material. Four loading conditions specified in the American Specification and Australian/New Zealand Standard for cold-formed stainless steel structures were investigated in the numerical study. A non-linear finite element model which includes geometric and material non-linearities was developed and verified against experimental results. It was shown that the finite element model closely predicted the web crippling strengths and failure modes of the tested specimens under the four loading conditions. Hence, parametric study was carried out to investigate the web crippling behaviour of cold-formed high strength stainless steel square and rectangular hollow sections at elevated temperatures. The web crippling strengths predicted from the finite element analysis were compared with the design strengths obtained using the American, Australian/New Zealand and European specifications for stainless steel structures by substituting the reduced material properties in the current web crippling design equations. A unified web crippling equation for cold-formed high strength stainless steel square and rectangular hollow sections at elevated temperatures is proposed. It is demonstrated that the web crippling strength obtained using the proposed equation is safe and reliable using reliability analysis. © 2013 Elsevier Ltd.

Chesi G.,University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2012

The Mahler measure provides a way to quantify the unstable and plays a key role in stabilization problems. This technical brief addresses the computation of the worst-case Mahler measure in systems depending polynomially on uncertain parameters constrained in a polytope. A sufficient condition for establishing an upper bound of the worst-case Mahler measure is provided in terms of linear matrix inequality (LMI) feasibility tests, where a homogeneous parameter-dependent quadratic Lyapunov function (HPD-QLF) is searched for. Moreover, it is shown that the best upper bound guaranteed by this condition can be obtained by solving generalized eigenvalue problems. Then, the conservatism of this methodology is investigated, showing that the upper bound is monotonically nonincreasing with the degree of the HPD-QLF, and that there exists a degree for which the upper bound is guaranteed to be tight. Some numerical examples illustrate the proposed results. © 1963-2012 IEEE.

Feng Z.,University of Hong Kong | Lam J.,University of Hong Kong
Signal Processing | Year: 2012

This paper is concerned with the problem of robust reliable dissipative filtering for uncertain discrete-time singular system with interval time-varying delay and sensor failures. The uncertainty and the sensor failures considered are polytopic uncertainty and varying in a given interval, respectively. The purpose is to design a filter such that the filtering error singular system is regular, causal, asymptotically stable and strictly (Q,S,R)-dissipative. By utilizing reciprocally convex approach, firstly, sufficient reliable dissipativity analysis condition is established in terms of linear matrix inequalities (LMIs) for singular systems with time-varying delay and sensor failures. Based on this criterion, the result is extended to uncertain singular systems with time-varying delay and sensor failures. Moreover, the reliable dissipative filter is designed in terms of linear matrix inequalities (LMIs) for uncertain singular systems with time-varying delay and sensor failures. Finally, the effectiveness of the filter design method in this paper is illustrated by numerical examples. © 2012 Elsevier B.V.

Lo S.H.,University of Hong Kong
Finite Elements in Analysis and Design | Year: 2012

A generic parallel Delaunay triangulation scheme by means of zonal partition of points is presented. For efficient Delaunay triangulation, points are first partitioned into cells, each of which is allocated roughly equal number of points. The cells can be naturally grouped into zones, in which Delaunay triangulation is constructed by simultaneous point insertion cell by cell within each zone. Delaunay triangles/tetrahedra at the boundary between zones can be created in parallel by adding layers of cells at the boundary of each zone to ensure circumcircles(circumspheres) of boundary triangles(tetrahedra) contain no points in their interior. Redundant triangles(tetrahedra) at the boundary between zones can be easily eliminated by individual processors in a completely independent manner by means of the elegant minimum vertex allocation scheme, such that a simplex with k vertices belonging to zones (z1, z2,... zk) is allocated to zone z=min (z1, z2,... zk). A two-dimensional version of the algorithm has been coded in Intel Fortran VS2010. The parallel zonal insertion on a PC can boost the speed of the single-processor insertion by 4.5 times for the insertion of 200 million randomly generated points in 65.7 s. The scalability of the parallel zonal insertion algorithm has also been tested on a proper multi-core machine with 12 processors running on OpenMP parallel directives with shared memory. Provided the number of zones is an integral multiple of the number of processors used, almost 100 scalability at 90 efficiency was observed for parallel insertion using 2, 4, 6, 8, 10 and 12 processors, and a 10.6 time speed up was recorded in a parallel insertion of 20 million points in 10×12=120 zones by 12 processors. © 2012 Elsevier B.V. All rights reserved.

Kwan K.H.,Nanyang Technological University | So P.L.,Nanyang Technological University | Chu Y.C.,University of Hong Kong
IEEE Transactions on Industrial Electronics | Year: 2012

This paper proposes a novel control design for the unified power quality conditioner (UPQC). This design, enabled by a control framework that employs the output regulation (OR) theory, is also made up of an exogenous Kalman filter used to extract the state components of the distorted supply voltage and load current, and a plant Kalman filter as a state observer. In addition, the same framework integrates the major functions of the UPQC with ease to unify the treatments of several power quality problems including system harmonics in the supply voltage and load current, sags/swells in the supply voltage, variations in the load demands, and poor power factor at the supply side. A linear quadratic regulator-based self-charging circuit is also incorporated into the control design so that the UPQC operates without relying on an external dc source. Simulation and experimental studies on a single-phase power distribution system are used to verify the performance and real-time implementation of this control design with the UPQC. © 2012 IEEE.

Chesi G.,University of Hong Kong
IEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans | Year: 2012

This correspondence addresses the analysis of the steady states of uncertain genetic regulatory networks (GRNs). The uncertainty is represented as a vector constrained in a given set that affects the coefficients of the mathematical model of the GRN. It is shown how regions containing all possible steady states can be estimated via an iterative strategy that progressively splits the concentration space into smaller sets, discarding those that are guaranteed not to contain equilibrium points of the considered model. This strategy is based on worst case evaluations of some appropriate functions of the uncertainty via linear matrix inequality optimization. © 2012 IEEE.

Lo S.H.,University of Hong Kong
Finite Elements in Analysis and Design | Year: 2012

A generic algorithm is proposed to merge structured and unstructured hexahedral meshes automatically into one single valid finite element mesh of hexahedral, tetrahedral and pyramid elements. In view of the success of merging arbitrary tetrahedral meshes in addressing the industrial need for rapid modification, update and manipulation of meshed objects, the merging algorithm is extended to hexahedral meshes by first dividing each hexahedral element into five or six tetrahedral elements. Non-intersected hexahedral elements can be easily recovered from the merged tetrahedral mesh as the constituent tetrahedra as a subdivision of the original hexahedral elements are intact and present in the mesh. Like the merging of tetrahedral meshes, the procedure is robust and efficient as all operations such as loops of intersection, incorporation of intersection segments, partition of boundary surfaces and identification of regions of intersection are deterministic and topological. The mesh merging algorithm provides a means to combine, modify and insert new features to existing hexahedral and tetrahedral meshes. It is also a powerful tool to create new meshes from existing hexahedral and tetrahedral meshes through the Boolean operations. High-quality regular hexahedral elements of the original mesh generated by mapping or extrusion will be preserved, which is important for finite element analysis as hexahedral elements are sensitive to shape distortions. Examples with details for each step of the mesh merging process are presented to elucidate the main ideas of the algorithm. © 2012 Elsevier B.V. All rights reserved.

Chui W.H.,University of Hong Kong | Chan H.C.,City University of Hong Kong
Child Abuse and Neglect | Year: 2013

Objective: Macau is a Special Administrative Region (SAR) of China with over 95% of the population is of Chinese descent. Research on school bullying using Macanese samples is virtually nonexistent. Thus, this study is among the first to sample this population by exploring the association between bullying perpetration and victimization, and the level of self-control among a group of school-aged Macanese adolescents. Methods: A total of 365 participants, aged between 10 and 17 years, from two male-only schools (a boarding and a non-boarding schools) in Macau are surveyed. The Illinois Bully Scale (Espelage & Holt, 2001) and Self-Control Scale (Grasmick, Tittle, Bursik, & Arneklev, 1993) are used to measure the participants bullying behaviors and self-control level, respectively. Results: Overall finding indicates that bullying perpetration is negatively associated with the participants' level of self-control. Conclusion: These findings provide further support for the importance of self-control in bullying perpetration. Implications of the findings are offered by way to increase the youngsters' level of self-control in order to reduce their propensity to engage in bullying perpetration at school. © 2012 Elsevier Ltd.

Chan T.M.,University of Hong Kong
Current Hepatitis Reports | Year: 2010

Glomerulonephritis is an important extrahepatic manifestation of chronic hepatitis B virus (HBV) infection. The uncommon occurrence, variability in renal histopathology, and heterogeneity in clinical course present challenges in clinical studies and have resulted in a relative paucity of data and uncertainty with regard to the optimal management of HBV-related glomerular diseases. The advent of nucleos(t)ide analogue medications that effectively suppress HBV replication has markedly altered the clinical outcomes of kidney transplant recipients with HBV infection, but the emergence of drug resistance is an escalating problem. This article reviews the recent knowledge of the pathogenesis and treatment of HBV-related membranous nephropathy, and discusses the management of hepatitis B in kidney transplant recipients, which is continuously evolving. © 2010 The Author(s).

Wang F.,University of Hong Kong | Shih K.,University of Hong Kong
Water Research | Year: 2011

The persistent nature of perfluorochemicals (PFCs) has attracted global concern in recent years. Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are the most commonly found PFC compounds, and thus their fate and transport play key roles in PFC distribution in the natural environment. As most solid phases in natural water contain alumina, an investigation of PFOS and PFOA adsorption behavior on alumina should prove useful in evaluating the environmental impact of this type of persistent pollutant. Systematic experiments were carried out in this study to investigate the adsorption behavior of PFOS and PFOA onto alumina. The results of adsorption kinetics on alumina show that it takes 48 h to reach equilibrium. The adsorption isotherms reveal maximum adsorption capacities of 0.252 μg/m2 for PFOS and 0.157 μg/m2 for PFOA at pH = 4.3, with the difference primarily due to their different functional groups. An increase in pH leads to a decrease in PFOS and PFOA adsorption on alumina, which may be attributed to the reduction in electrostatic interaction. The adsorption of both PFOS and PFOA decreases with an increase in ionic strength for all four types of cations (Na+, K+, Mg2+, and Ca2+), due to the compression of the electrical double layer. Furthermore, the results also indicate that both Ca2+ and Mg2+ can form bridges with PFOA anions in solution, whereas only PFOS can be bridged by Ca2+ due to the higher covalent nature of magnesium. © 2011 Elsevier Ltd.

Yang J.,University of Hong Kong | Sze H.Y.,University of Hong Kong
Geotechnique | Year: 2011

This paper reports findings from an experimental study that aimed to investigate the undrained behaviour of sand in non-symmetrical cyclic loading, and to clarify the role of initial static shear in liquefaction resistance. The testing programme, conducted on a standard sand under triaxial conditions, covers a broad range of initial states in terms of relative density, confining stress and initial shear stress ratio (α). Three distinct failure modes have been identified from the tests: flow-type failure, cyclic mobility and plastic strain accumulation. Of these, flowtype failure, characterised by abrupt runaway deformations without any prior warning, is the most critical, and pertains to sand in the loose state. The tests also demonstrate that the presence of initial static shear stress is beneficial to the liquefaction resistance of loose sand at low α levels, but it becomes detrimental at high Φ levels. In this connection the concept of threshold α is proposed, together with the use of a no-stress-reversal line for better characterisation of the effect of initial static shear. Furthermore, in the conceptual framework of critical state soil mechanics, a fairly good linear relationship has been established between the threshold α and the state parameter Φ that collectively accounts for the initial relative density and mean stress level. This relationship suggests that the threshold α decreases with increasing values of Φ, or with sand becoming looser than the critical state. It is further proposed that the concept of threshold α also applies to sand at high relative density, as long as the confining stress becomes sufficiently high. This proposal leads to a unified and consistent interpretation of the complicated static shear effect.

Ip C.K.M.,University of Hong Kong | Wong A.S.T.,University of Hong Kong
Expert Opinion on Therapeutic Targets | Year: 2012

The p70 S6 kinase (p70 S6K) is frequently active in ovarian and a wide range of cancer types, and it has a crucial role in several processes considered hallmarks of cancer. Therefore, blocking p70 S6K expression or activity may present a promising strategy for anticancer treatment. Areas covered: The current understanding of the molecular mechanisms that govern p70 S6K regulation as well as its tumorigenic effects, which are involved in the initiation and progression in ovarian cancer, in particular the emerging new role of p70 S6K in cell migration, which is a prerequisite of tumor metastasis. The p70 S6K cellular substrates and/or interacting proteins. The current state of drugs that target this kinase, either alone or in combination with other targeted agents. Expert opinion: Targeting p70 S6K through the use of small-molecule inhibitors, microRNAs and natural compounds may represent a beneficial new avenue for cancer therapy and opens new areas of investigation in p70 S6K biology. © 2012 Informa UK, Ltd.

Xu A.,University of Hong Kong | Vanhoutte P.M.,University of Hong Kong | Vanhoutte P.M.,King Saud University
American Journal of Physiology - Heart and Circulatory Physiology | Year: 2012

The heart and blood vessels are surrounded by epicardial and perivascular adipose tissues, respectively, which play important roles in maintaining cardiovascular homeostasis by secreting a number of biologically active molecules, termed "adipokines." Many of these adipokines function as an important component of the 'adipo-cardiovascular axis' mediating the cross talk between adipose tissues, the heart, and the vasculature. On the one hand, most adipokines [including tumor necrosis factor-α, resistin, adipocyte fatty acid binding protein (A-FABP), and lipocalin-2] are proinflammatory and causally associated with endothelial and cardiac dysfunction by their endocrine/paracrine actions. On the other hand, adiponectin is one of the few adipokines that possesses multiple salutary effects on the prevention of cardiovascular disease, because of its pleiotropic actions on the heart and the blood vessels. The discordant production of adipokines in dysfunctional adipose tissue is a key contributor to obesity-related cardiovascular disease. This review provides an update in understanding the roles of adipokines in the pathogenesis of cardiovascular disorders associated with obesity and diabetes and focuses on the two most abundant adipokines, adiponectin and A-FABP. Indeed, data from both animal studies and clinical investigations imply that these two adipokines are prognostic biomarkers for cardiovascular disease and even promising therapeutic targets for its treatment. © 2012 the American Physiological Society.

Ju F.,University of Hong Kong | Zhang T.,University of Hong Kong
Applied Microbiology and Biotechnology | Year: 2015

The ubiquitous occurrence of microorganisms gives rise to continuous public concerns regarding their pathogenicity and threats to human environment, as well as potential engineering benefits in biotechnology. The development and wide application of environmental biotechnology, for example in bioenergy production, wastewater treatment, bioremediation, and drinking water disinfection, have been bringing us with both environmental and economic benefits. Strikingly, extensive applications of microscopic and molecular techniques since 1990s have allowed engineers to peep into the microbiology in “black box” of engineered microbial communities in biotechnological processes, providing guidelines for process design and optimization. Recently, revolutionary advances in DNA sequencing technologies and rapidly decreasing costs are altering conventional ways of microbiology and ecology research, as it launches an era of next-generation sequencing (NGS). The principal research burdens are now transforming from traditional labor-intensive wet-lab experiments to dealing with analysis of huge and informative NGS data, which is computationally expensive and bioinformatically challenging. This study discusses state-of-the-art bioinformatics and statistical analyses of 16S ribosomal RNA (rRNA) gene high-throughput sequencing (HTS) data from prevalent NGS platforms to promote its applications in exploring microbial diversity of functional and pathogenic microorganisms, as well as their interactions in biotechnological processes. © 2015, Springer-Verlag Berlin Heidelberg.

Chesi G.,University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2015

This technical note investigates two instability measures in continuous-time (CT) and discrete-time (DT) uncertain systems, the first given by the spectral abscissa (CT case) or radius (DT case), and the second given by the sum (CT case) or product (DT case) of the unstable eigenvalues. It is supposed that the system depends polynomially on an uncertain vector constrained into a semi-algebraic set. The problem is to determine the largest instability measures over the admissible uncertainties. It is shown that a sufficient condition for establishing an upper bound of the sought measures can be obtained in terms of linear matrix inequality (LMI) feasibility tests by exploiting the determinants of some specific matrices, and that this condition is also necessary under some mild conditions on the semi-algebraic set by using multipliers with degree sufficiently large. Moreover, a condition is provided for establishing the tightness of the found best upper bounds. Lastly, it is shown that in the special case where the semi-algebraic set is an interval, the degree of the multipliers is known a priori. Some numerical examples illustrate the proposed results. © 1963-2012 IEEE.

Chen W.T.,University of Hong Kong | Zhou M.-F.,University of Hong Kong
Economic Geology | Year: 2012

The Lala Fe-Cu deposit in the Kangdian iron oxide copper-gold (IOCG) metallogenic province, SW China, is hosted in the Paleoproterozoic Hekou Group. This volcanic-sedimentary sequence has undergone upper greenschist-lower amphibolite facies metamorphism at ~850 Ma. The deposit contains more than 200 million metric tons (Mt) of Fe-Cu ores with an average grade of 13 wt % Fe and 0.92 wt % Cu. Orebodies are roughly strata bound but occur along foliation, lithologic contacts, and shear zones. The paragenetic sequence of the Lala deposit includes metamorphosed (I, II, and III) and unmetamorphosed (IV and V) stages. Stage I is characterized by extensively pervasive Na alteration, forming abundant albite but minor scapolite. Stage II occurs as massive and banded replacements, consists of Ti-V-poor magnetite and apatite with minor disseminated sulfide minerals, and was associated with pervasive K-Fe alterations forming K-feldspar, chlorite, and actinolite. Stage III occurs predominantly as bands and disseminations confined along foliations with minor veinlets crosscutting hosting rocks. This stage is characterized by abundant Fe-Cu-Mo sulfides intergrown with angular magnetite and minor titanite and allanite and is associated with alteration of carbonate, quartz, fluorite, and mica. Stage IV has an assemblage dominated by chalcopyrite with variable pyrite and bornite, occurring as veins of sulfides + quartz + calcite + biotite ± muscovite ± fluorite. Stage V occurs chiefly as veins of hematite ± calcite ± quartz and also results in extensive hematization. Stages II and III have fluids with high δ 18O (7.2-11.7‰) and δ 34S values (0-4‰), indicative of a magmatichydrothermal origin. However, the stage III fluids have δ34C values (~0.5‰) close to the least altered marble (0-2‰) of the hosting rocks, indicating a possible contribution of strata-sourced carbon. The stage IV fluids have δ34C values similar to and δ 18O (4.1-6.7‰) lower than the stage III fluids, and a wider range of δ 34S values (-9.0 to +10.5‰), consistent with significant contributions of strata-sourced sulfur. Fluids of the late barren vein stage (V) have relatively low δ34C (-4.0 to -2.4‰) and δ 18O values (-2.9 to +0.6‰), indicative of significant contributions of meteoric and oxidized fluids. Molybdenite from stage III has an Re-Os isotope age of 1086 ± 8 Ma, providing tight constraints on the timing of the main stage of mineralization. This age indicates that the Lala deposit is coeval with the ~1100 Ma intraplate magmatism in the western Yangtze Block. We propose that the majority of the Fe-Cu deposits in the Kangdian IOCG metallogenic province may have formed in an intraplate extensional setting, although it is possible that some of the deposits may have involved in multiple events including modification by the Neoproterozoic metamorphism forming the mineral assemblages of stage IV. © 2012 Society of Economic Geologists, Inc.

Cheung J.P.,University of Hong Kong
Journal of orthopaedic surgery (Hong Kong) | Year: 2010

Misdiagnosis and delayed treatment of Mycobacterium marinum infection is common because of its diverse manifestations. This leads to inappropriate use of antimicrobials, extension of the infection from the skin to the tenosynovium, and a poor prognosis (loss of tendons and prolonged immobilisation, secondary to multiple debridements and joint contractures). Clinicians should be aware of this type of infection, especially in subjects at risk (fishermen and aquarium enthusiasts), and those with a history of trauma coupled with exposure to water or marine life. A proactive approach to obtain a biopsy for histopathological and microbiological diagnosis is advised. Anti-mycobacterial treatment should be started promptly. The combined use of rifampicin, ethambutol, and clarithromycin appears to be effective, and debridement is indicated in patients with deep-seated infections.

Li H.C.,University of Hong Kong
Psycho-oncology | Year: 2011

The treatment of cancer is a stressful and threatening experience, particularly for children. Knowing how children cope with cancer is a crucial step toward designing appropriate psychological interventions that help them ease the burden of cancer treatment. The purpose of this study was to examine the coping strategies used by Chinese children hospitalized with cancer, an area of research that is under-represented in the existing literature. Hong Kong Chinese children (9-16-year olds) admitted for cancer treatment to the pediatric oncology units of two different regional acute public hospitals were invited to participate. A short one-to-one structured interview was conducted with each participant. Content analysis was conducted to analyze the interview data. A convenience sample of 88 children was recruited and participated in the interviews during an 8-month period. The coping strategies used by Chinese children hospitalized with cancer did not differ according to gender and diagnosis, but only according to age, with younger children using less problem-focused and more emotion-focused coping strategies than older children. The overall results indicated that 30% of these Chinese patients used problem-focused coping strategies, while 70% used emotion-focused coping. Findings from this study indicated that children use different coping strategies at different developmental stages. The study also revealed that Chinese children used more emotion-focused than problem-focused coping strategies than their Western counterparts. The information derived from this study will help health-care professionals design and shape appropriate psychological interventions that can help reduce the burden of cancer treatment. Copyright © 2010 John Wiley & Sons, Ltd. Copyright © 2010 John Wiley & Sons, Ltd.

Ngai F.-W.,University of Hong Kong | Ngu S.-F.,University of Hong Kong
Journal of Psychosomatic Research | Year: 2015

Objectives: Postnatal depression has emerged as a major public health concern, which has deleterious effects on the well-being of the entire family. The aim of this study was to examine the predictive role of prenatal family sense of coherence, stress, social support and family, and marital functioning; the effect that any changes in these factors from pregnancy to postpartum; and partner's depressive symptoms on depressive symptoms at 6. months postpartum. Methods: This study used a longitudinal design. A convenience sample of 200 childbearing couples in Hong Kong completed assessments of family sense of coherence, stress, social support, family, and marital functioning and depressive symptoms during pregnancy and at 6. months postpartum. Multiple regression analyses were employed. Results: The results showed that a low level of family sense of coherence and a high level of depressive symptoms during pregnancy and partner's depressive symptoms were significantly associated with an increase in depressive symptoms for both mothers and fathers at 6. months postpartum. A lack of social support was significantly associated with increased risk of depressive symptoms for mothers, but not for fathers. Conclusion: The results suggest that couple-based interventions that foster a sense of family coherence may be helpful in promoting parental well-being. Well-designed trials to test the effects of such interventions are recommended for future research. © 2014 Elsevier Inc.

Wang M.,University of Hong Kong
Information Systems Frontiers | Year: 2011

E-learning is emerging as a popular approach of education in the workplace by virtue of its flexibility to access, just-in-time delivery, and cost-effectiveness. To improve social interaction and knowledge sharing in e-learning, Web 2.0 is increasingly utilized and integrated with e-learning applications. However, existing social learning systems fail to align learning with organizational goals and individual needs in a systemic way. The dominance of technology-oriented approaches makes elearning applications less goal-effective and poor in quality and design. To solve the problem, we address the requirement of integrating organizational, social, and individual perspectives in the development of Web 2.0 elearning systems. To fulfill the requirement, a key performance indicator (KPI)-oriented approach is presented in this study. By integrating a KPI model with Web 2.0 technologies, our approach is able to: 1) set up organizational goals and link the goals with expertise required for individuals; 2) build a knowledge network by linking learning resources to a set of competences to be developed and a group of people who learn and contribute to the knowledge network through knowledge creation, sharing, and peer evaluation; and 3) improve social networking and knowledge sharing by identifying each individual's work context, expertise, learning need, performance, and contribution. The mechanism of the approach is explored and elaborated with conceptual frameworks and implementation technologies. A prototype system for Web 2.0 e-learning has been developed to demonstrate the effectiveness of the approach. © Springer Science + Business Media, LLC 2009.

Chesi G.,University of Hong Kong
IEEE Transactions on Robotics | Year: 2010

Image noise unavoidably affects the available image points that are used in visual-servoing schemes to steer a robot end-effector toward a desired location. As a consequence, letting the image points in the current view converge to those in the desired view does not ensure that the camera converges accurately to the desired location. This paper investigates the selection of object configurations to minimize the worst-case positioning error due to the presence of image noise. In particular, a strategy based on linear matrix inequalities (LMIs) and barrier functions is proposed to compute upper and lower bounds of this error for a given maximum error of the image points. This strategy can be applied to problems such as selecting an optimal subset of object points or determining an optimal position of an object in the scene. Some examples illustrate the use of the proposed strategy in such problems. © 2010 IEEE.

Djurisic A.B.,University of Hong Kong | Chen X.,University of Hong Kong | Leung Y.H.,University of Hong Kong | Man Ching Ng A.,University of Hong Kong | Man Ching Ng A.,South University of Science and Technology of China
Journal of Materials Chemistry | Year: 2012

ZnO is a material which is of great interest for a variety of applications due to its unique properties and the availability of a variety of growth methods resulting in a number of different morphologies and a wide range of material properties of synthesized nanostructures. In this review, we will discuss recent advances in important and/or controversial issues concerning ZnO properties and its applications. We will also discuss areas where further improvements are needed, and in particular discuss the issues related to the environmental stability of ZnO and its implications on reproducibility of measurements and the toxicity of ZnO nanomaterials. © The Royal Society of Chemistry 2012.

Chan K.L.,University of Hong Kong
Child Abuse and Neglect | Year: 2014

Multiple forms of violence may co-occur on a child. These may include various forms of child victimization and different types of family violence. However, evidence that child victims are more likely to witness other types of family violence has been lacking in China. Using data of a large and diverse sample of children recruited from 6 regions in China during 2009 and 2010 (N= 18,341; 47% girls; mean age. = 15.9 years), the associations between child victimization and family violence witnessed were examined. Descriptive statistics and the associations between child victimization, demographic characteristics, and family violence witnessed were analyzed. Lifetime and preceding-year rates were 71.7% and 60.0% for any form of child victimization and 14.0% and 9.2% for poly-victimization (having four or more types of victimization), respectively. Family disadvantages (i.e., lower socio-economic status, single parents, and having more than one child in the family) were associated with child victimization and poly-victimization. Witnessing of parental intimate partner violence, elder abuse, and in-law conflict also increased the likelihood of child victimization and poly-victimization, even after the adjustment of demographic factors. Possible mechanisms for the links between family violence and child victimization are discussed. The current findings indicated the need for focusing on the whole family rather than the victim only. For example, screening for different types of family violence when child victims are identified may help early detection of other victims within the family. © 2014 Elsevier Ltd.

Yang J.,University of Hong Kong | Wei L.M.,University of Hong Kong
Geotechnique | Year: 2012

This paper describes a fundamental study to explore the role of particle shape in the shear behaviour of mixtures of sand and fine particles (fines) through macro-scale and grain-scale laboratory experiments together with interpretations in the framework of critical state soil mechanics and conceptual micromechanics models. Two non-plastic fines of distinct shape (angular crushed silica fines and rounded glass beads) were added to two uniform quartz sands (Toyoura sand and Fujian sand) to produce four binary mixtures. Laboratory quantification of particle shape and size was conducted for both fines and sands, and a series of undrained triaxial tests was performed to investigate the overall response of the mixed soils at different percentages of fines. One of the significant findings is that the critical state friction angle of a mixed soil is affected not only by the shape of coarse particles but also by the shape of fine particles, and this shape effect is coupled with fines content. When a small amount of crushed silica fines was added to either Toyoura sand or Fujian sand, the critical state friction angle increased slightly with fines content; however, when a small amount of glass beads was added to either sand, the critical state friction angle decreased markedly with an increase in fines content. A new index, termed combined roundness, is proposed to account for the coupled effects of particle shape and fines content. The study also provides evidence showing that the undrained shear behaviour and collapsibility of a mixed soil are closely related to the shape of its constituent particles: a mixed soil containing rounded fines tends to exhibit higher susceptibility to collapse than a mixed soil containing angular fines of the same percentage, and this tendency will become more evident if the base sand is also composed of rounded particles. In addition, the study provides the first experimental evidence showing that the quasi-steady state marks a transition from a metastable to a stable microstructure. It is postulated that in a binary mixture composed of fine and coarse particles that are both rounded, the particles favour rolling, thus yielding a microstructure that is unstable, whereas in a binary mixture composed of fine and coarse particles that are both angular, the particles favour sliding rather than rolling, thus leading to a much more stable structure and response.

Zhu J.-H.,Shenzhen University | Young B.,University of Hong Kong
Journal of Constructional Steel Research | Year: 2012

This paper presents the numerical simulation and design of cold-formed steel oval hollow section columns. An accurate finite element model was developed to simulate the fixed-ended column tests of oval hollow sections. The material non-linearities obtained from tensile coupon tests as well as the initial local and overall geometric imperfections were incorporated in the finite element model. Convergence study was performed to obtain the optimized mesh size. A parametric study consisted of 100 columns was conducted using the verified numerical model. The failure modes of material yielding, local buckling and flexural buckling as well as interaction of local and flexural buckling were found in this study. The experimental column strengths and numerical results predicted by the parametric study were compared with the design strengths calculated using the current North American, Australian/New Zealand and European specifications for cold-formed steel structures. In addition, the direct strength method, which was developed for cold-formed steel members for certain cross-sections but not cover oval hollow sections, was used in this study. The reliability of these design rules was evaluated using reliability analysis. © 2011 Elsevier Ltd. All rights reserved.

Wong V.,University of Hong Kong
The Cochrane database of systematic reviews | Year: 2013

Traumatic brain injury (TBI) can be life threatening depending on the severity of the insult to the brain. It can also cause a range of debilitating sequelae which require cognitive, motor, communication, emotional, or behavioral rehabilitation of varying intensity and duration. A number of studies conducted and published in China have suggested that acupuncture may be beneficial in the acute treatment and rehabilitation of TBI. To determine the efficacy and safety of acupuncture in the acute management or rehabilitation (or both) of patients with a TBI, including cognitive, neurological, motor, communication, emotional, or behavioral complications, or a combination of such complications. We searched the Cochrane Injuries Group Specialised Register, Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, AMED, PsycINFO and others. We also searched the Chinese Acupuncture Studies Register, the Studies Register of the Cochrane Complementary Medicine Field, NCCAM, and NIH Clinical Studies Database. Three major Mainland Chinese academic literature databases (CNKI, VIP and Wang Fang Data) were also searched using keywords in simplified Chinese. We searched all databases through December 2009, and some searches have been updated to October 2012. Randomized controlled studies evaluating different variants of acupuncture and involving participants of any age who had suffered a TBI. Included trials compared acupuncture with placebo or sham treatment, or acupuncture plus other treatments compared with the same other treatments. We excluded trials that only compared different variants of acupuncture or compared acupuncture alone against other treatments alone, as they did not yield the net effect of acupuncture. Two review authors identified potential articles from the literature search and extracted data independently using a data extraction form. We performed methodological assessment of included studies using the Cochrane Collaboration's tool for assessing risk of bias. We were unable to perform quantitative data analysis due to insufficient included studies and available data. Four RCTs, including 294 participants, reported outcomes specified by this review. Three investigated electro-acupuncture for TBI while one investigated acupuncture for acute TBI. The results seem to suggest that acupuncture is efficacious for these indications, however the low methodological quality of these studies renders the results questionable. No adverse effects of acupuncture were reported in any of the studies. The low methodological quality of the included studies does not allow us to make conclusive judgments on the efficacy and safety of acupuncture in either the acute treatment and/or rehabilitation of TBI. Its beneficial role for these indications remains uncertain. Further research with high quality trials is required.

Lin I.W.-S.,University of Hong Kong | Lok C.-N.,University of Hong Kong | Che C.-M.,University of Hong Kong
Chemical Science | Year: 2014

The synthesis of metal nanoparticles by using bacteria is of growing interest in nanobiotechnology as well as in the study of microbial metal metabolism. Some silver-resistant bacteria can produce considerable amounts of silver particles when exposed to silver salts at high concentration but the mechanism of biosynthesis is unknown. In this work, an Escherichia coli strain that carries chromosomally encoded silver resistance determinants has been shown to produce silver nanoparticles in the periplasmic space when it was exposed to Ag(i) salts, providing a prototypical model for studying the biosynthesis of silver nanoparticles. The synthesized silver nanoparticles are in the form of a zero-valent metallic silver lattice, and the production of which was observed to be favorable under anaerobic conditions, suggestive of the biological reduction of Ag+ ions. As the microbial c-type cytochromes are known to mediate respiratory reduction of metal ions, their role in the biosynthesis of silver nanoparticles was examined. A deletion mutant of the cytoplasmic membrane-anchored tetra-heme c-type cytochrome subunit of periplasmic nitrate reductase (NapC) showed markedly reduced production of silver nanoparticles. On the other hand, re-introduction of the NapC could recover the biosynthesis of the silver nanoparticles. This study has identified a molecular mechanism of biosynthesis of silver nanoparticles involving c-type cytochromes, having implications in the bioenvironmental process of mineralization and the synthetic biology of metal nano-materials. © the Partner Organisations 2014.

Through the incorporation of triethylene glycol (TEG) units into platinum(ii) bzimpy complexes and by various spectroscopic and microscopy studies, an unusual thermo-responsive behaviour, which is distinct from those of other ethylene glycol-pendant compounds, was observed. The unprecedented existence of the large hysteresis resulting from the supramolecular assembly of the platinum(ii) metallo-amphiphile has enabled the memory capability of the system. This journal is © the Partner Organisations 2014.

Wong W.S.,The Hong Kong Institute of Education | Fielding R.,University of Hong Kong
Journal of Affective Disorders | Year: 2010

Background: Epidemiologic data is available on chronic fatigue for Western, but not for Chinese populations. The aims of the present study were to determine the prevalence of chronic fatigue in the general population of Hong Kong, compare health and lifestyle characteristics of non-chronic fatigue and chronic fatigue cases, and identify risk factors for chronic fatigue. Methods: We performed telephone interviews on 5001 randomly selected Chinese adults aged ≥ 18 years administering the Chinese version of Chronic Fatigue Scale (ChCFS), the Hospital Anxiety and Depression Scale (HADS), and quality of life (QoL) indexed by Medical Outcomes Study 12-item Short-Form Health Survey (SF12). Lifestyle, and sociodemographic data were also collected. Chronic fatigue was defined according to Fukuda et al.'s (1994) criteria and case criterion was a ChCFS total scores ≥ 4. Results: The weighted prevalence of chronic fatigue was 10.7%, which was equivalent to 0.6 million adults in Hong Kong. Higher prevalence rates were found in females, older age groups, and low socioeconomic status. Fully adjusted stepwise regression analyses identified older age, retirees, housewife, existing long-term health problems, higher HADS scores, poor QoL, and low self-perceived health to be significantly associated with increased risk of chronic fatigue, whereas regular exercise was associated with decreased risk of chronic fatigue (all p < 0.05). Limitations: The cross-sectional design did not allow determination of the time course and causal relationship between chronic fatigue and associated factors. Conclusions: Our data evidenced that chronic fatigue is common in the general population of Hong Kong, and the prevalence increased with age and was higher in the women and lower socioeconomic population. © 2010 Elsevier B.V. All rights reserved.

A series of amphiphilic sulfonate-pendant platinum(ii) bzimpy complexes with different lengths of alkyl chains on the alkynyl ligands has been found to show unusual absorption and emission behavior with changes to the length of the alkyl chain. The spectroscopic changes are found to be associated with the formation of self-assembled nanostructures and through the studies of their spectroscopic properties and aggregate morphology, further insights into the relationship between the molecular structures and their molecular packing are obtained. © 2014 the Partner Organisati