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Hong Kong, China

The Chinese University of Hong Kong is a public research university in Shatin, Hong Kong, formally established in 1963 by a charter granted by the Legislative Council of Hong Kong. It is the territory's second oldest institution of higher learning, and the only collegiate university. The University was originally founded as a federation of three existing colleges, Chung Chi College, New Asia College and United College, the oldest of which was founded in 1949.Today, CUHK is organised into nine constituent colleges and eight academic faculties. Though the original statement in the charter of the University stipulates Chinese as the principal language, English is currently the main language of instruction in most classes, with Cantonese and Mandarin Chinese being retained only by a minority of colleges and academic departments. As of 2013, four Nobel laureates are associated with the University, making it the only tertiary institution in the territory with recipients of the Nobel Prize, Turing Award, Fields Medal and Veblen Prize as faculty in residence. Wikipedia.


Yuan X.,Chinese University of Hong Kong | Ping L.,City University of Hong Kong
IEEE Transactions on Signal Processing | Year: 2012

We propose a low-complexity dual-diagonal (DD-) linear-minimum-mean-square- error (LMMSE) channel estimation algorithm for orthogonal frequency-division multiplexing (OFDM) systems involving iterative channel estimation and signal detection. Computational complexity and mean-square-error (MSE) analysis are presented to evaluate the efficiency of the proposed algorithm. A closed-form expression is derived for the asymptotic MSE of the DD-LMMSE channel estimator. Both analysis and numerical results show that DD-LMMSE performs close to the well-known LMMSE estimator with much lower complexity. © 1991-2012 IEEE. Source


Wong G.W.K.,Medicine and Therapeutics | Leung T.F.,Medicine and Therapeutics | Ko F.W.S.,Chinese University of Hong Kong
Allergy, Asthma and Immunology Research | Year: 2013

Asia-Pacific is one of the most densely populated regions of the world and is experiencing rapid economic changes and urbanization. Environmental pollution is a significant problem associated with the rapid modernization of many cities in South Asia. It is not surprising that the prevalences of asthma and allergies are increasing rapidly, although the underlying reasons remain largely unknown. Many studies from this region have documented the changing prevalence of allergic diseases in various parts of the world. However, the methodologies used were neither standardized nor validated, making the results difficult to evaluate. The International Study of Asthma and Allergies in Childhood (ISAAC) has provided a global epidemiology map of asthma and allergic diseases, as well as the trend of changes in the prevalence of these diseases. Allergic sensitization is extremely common in many Asian communities. However, the prevalence of allergic diseases remains relatively rare. The rapid urbanization in the region, which increases environmental pollution and can affect the rural environment, will likely increase the prevalence of asthma and allergies in Asia. © The Korean Academy of Asthma, Allergy and Clinical Immunology. Source


Zhang W.,University of California at Berkeley | Cham W.-K.,Chinese University of Hong Kong
Journal of Visual Communication and Image Representation | Year: 2012

Unlike high dynamic range (HDR) imaging, exposure fusion is a process of generating a tonemapped-like HDR image directly by fusing a series of bracketed images. Since it frees users from the tedious radiometric calibration and tone mapping steps, this technique is getting more and more popular, and becomes a basic tool in many graphics software. The main drawback of exposure fusion is its limitation to static scenes and any object movement of the target scene will incur severe ghosting artifacts in the fused result. In this paper, we intend to overcome this limitation and make exposure fusion applicable in dynamic scenes. A new quality assessment system is developed, where both temporal consistency and spatial consistency are introduced to account for ghosting artifacts. Experimental results of various dynamic scenes are shown to prove the effectiveness of the proposed method. © 2011 Elsevier Inc. All rights reserved. Source


Wang F.,China Academy of Space Technology | Huang J.,Chinese University of Hong Kong | Zhao Y.,Peking University
IEEE Transactions on Wireless Communications | Year: 2012

Supporting the quality of service of unlicensed users in cognitive radio networks is very challenging, mainly due to the dynamic resource availability induced by the licensed users' activities. In this paper, we derive the optimal admission control and channel allocation decisions in cognitive overlay networks to support delay sensitive communications of unlicensed users. We formulate it as a Markov decision process problem, and solve it by transforming the original formulation into a stochastic shortest path problem. We then propose a simple heuristic control policy, which includes a threshold-based admission control scheme and and a largest-delay-first channel allocation scheme, and prove the optimality of the largest-delay-first channel allocation scheme. We further propose an improved policy using the rollout algorithm. By comparing the performance of both proposed policies with the upper-bound of the maximum revenue, we show that our policies achieve close-to-optimal performances with low complexities. © 2012 IEEE. Source


Duan L.,Singapore University of Technology and Design | Huang J.,Chinese University of Hong Kong | Shou B.,City University of Hong Kong
IEEE Transactions on Mobile Computing | Year: 2012

This paper presents a comprehensive analytical study of two competitive secondary operators' investment (i.e., spectrum leasing) and pricing strategies, taking into account operators' heterogeneity in leasing costs and users' heterogeneity in transmission power and channel conditions. We model the interactions between operators and users as a three-stage dynamic game, where operators simultaneously make spectrum leasing decisions in Stage I, and pricing decisions in Stage II, and then users make purchase decisions in Stage III. Using backward induction, we are able to completely characterize the dynamic game's equilibria. We show that both operators' investment and pricing equilibrium decisions process interesting threshold properties. For example, when the two operators' leasing costs are close, both operators will lease positive spectrum. Otherwise, one operator will choose not to lease and the other operator becomes the monopolist. For pricing, a positive pure strategy equilibrium exists only when the total spectrum investment of both operators is less than a threshold. Moreover, two operators always choose the same equilibrium price despite their heterogeneity in leasing costs. Each user fairly achieves the same service quality in terms of signal-to-noise ratio (SNR) at the equilibrium, and the obtained predictable payoff is linear in its transmission power and channel gain. We also compare the duopoly equilibrium with the coordinated case where two operators cooperate to maximize their total profit. We show that the maximum loss of total profit due to operators' competition is no larger than 25 percent. The users, however, always benefit from operators' competition in terms of their payoffs. We show that most of these insights are robust in the general SNR regime. © 2012 IEEE. Source


Qian F.,Xian University of Technology | Gao J.,Shanghai JiaoTong University | Li D.,Chinese University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2012

As the performance index of the linear-quadratic-Gaussian (LQG) problem is governed by the noncentral generalized Chi-square distribution, solely controlling the expected value of the performance index, as the traditional LQG theory aims at, is insufficient to deliver a satisfactory solution in some situations. While the risk sensitive control does control a specific weighting sum of various moments of the performance index, the single degree of freedom in adjusting the weighting coefficients in this specific weighting sum of various moments of the performance index often prevents the risk sensitive control from generating a desired pattern of high order moment-distribution. We achieve in this note the complete statistical characterization of the performance index for the discrete-time LQG formulation. More specifically, we derive a recursive relationship to obtain cumulants of various orders of the performance index successively. Parameterized in feedback gain, the optimal feedback control law can be computed off-line by solving a static polynomial optimization problem, thus serving two design goals: i) To shape the probability density function (pdf) of the performance index to attain, at least approximately, a given desired pattern by regulating cumulants of various orders, and ii) to improve the performance measure of an incumbent solution (generated by the risk sensitive control, for example) by adjusting the levels of cumulants of various orders. © 2012 IEEE. Source


Zhang S.,Shenzhen University | Liew S.-C.,Chinese University of Hong Kong | Wang H.,Shenzhen University
IEEE Journal on Selected Areas in Communications | Year: 2013

This paper investigates interference-cancellation schemes at the receiver, in which the interference data, which is valid data intended for another receiver, is known a priori. The interference channel, however, is unknown (the blind part). Such a priori knowledge is common in wireless relay networks. For example, a relay could be relaying data that was previously transmitted by a node A. If node A is now receiving a signal from another node B, the interference from the relay is actually self-information known to node A. Besides the case of self-information, the node could also have overheard or received the interference data in a prior transmission by another node. Directly removing the known interference requires accurate estimate of the interference channel, which may be difficult in many situations. In this paper, we propose a novel scheme, Blind Known-Interference Cancellation (BKIC), to cancel known interference without interference channel information. BKIC consists of two steps. The first step combines adjacent symbols to cancel the interference, exploiting the fact that the channel coefficients are almost the same between successive symbols. After such interference cancellation, however, the signal of interest is distorted. The second step recovers the signal of interest amidst the distortion. We propose two algorithms for the critical second steps. The first algorithm (BKIC-S) is based on the principle of smoothing. It is simple and has near optimal performance in the slow fading scenario. The second algorithm (BKIC-RBP) is based on the principle of real-valued belief propagation. Since there is no loop in the Tanner graph, BKIC-RBP can achieve MAP-optimal performance with fast convergence, and has near interference-free performance even in the fast fading scenario. Both BKIC schemes outperform the traditional self-interference cancellation schemes that have perfect initial channel information by a large margin, while having lower complexities. © 2013 IEEE. Source


Wang F.,Beijing Jiaotong University | Liew S.C.,Chinese University of Hong Kong | Guo D.,Northwestern University
IEEE Journal on Selected Areas in Communications | Year: 2012

A wireless relay with multiple antennas is called a multiple-input- multiple-output (MIMO) switch if it maps its input links to its output links using precode-and-forward. Namely, the MIMO switch precodes the received signal vector in the uplink using some matrix for transmission in the downlink. This paper studies the scenario of K stations and a MIMO switch, which has full channel state information. The precoder at the MIMO switch is either a zero-forcing matrix or a network-coding matrix. With the zero-forcing precoder, each destination station receives only its desired signal with enhanced noise but no interference. With the network-coding precoder, each station receives not only its desired signal and noise, but possibly also self-interference, which can be canceled. Precoder design for optimizing the received signal-to-noise ratios at the destinations is investigated. For zero-forcing relaying, the problem is solved in closed form in the two-user case, whereas in the case of more users, efficient algorithms are proposed and shown to be close to what can be achieved by extensive random search. For network-coded relaying, we present efficient iterative algorithms that can boost the throughput further. © 2012 IEEE. Source


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

Proper patrol route planning increases the effectiveness of police patrolling and improves public security. In this paper, we present a new approach for real-time patrol route planning in dynamic environments. We first build a mathematical formulation for the patrol route planning problem under a single patrol unit setting and then propose a fast algorithm developed from the cross entropy (CE) method to meet the real-time computation requirements needed for practical applications. We next generalized the result to the patrol team case. Since the size of feasible team routes grows exponentially as the number of patrol units increases, we propose an approximate CE (ACE) algorithm that balances convergence time with optimality. Compared with the CE algorithm, the ACE algorithm can reduce the convergence time by as much as 48.9% with a less than 1% performance loss. © 2012 IEEE. Source


Feng D.-J.,Chinese University of Hong Kong | Huang W.,Anhui University of Science and Technology
Communications in Mathematical Physics | Year: 2010

For general asymptotically sub-additive potentials (resp. asymptotically additive potentials) on general topological dynamical systems, we establish some variational relations between the topological entropy of the level sets of Lyapunov exponents, measure-theoretic entropies and topological pressures in this general situation. Most of our results are obtained without the assumption of the existence of unique equilibrium measures or the differentiability of pressure functions. Some examples are constructed to illustrate the irregularity and the complexity of multifractal behaviors in the sub-additive case and in the case that the entropy map is not upper-semi continuous. © 2010 Springer-Verlag. Source


Pong S.-L.,Pennsylvania State University | Pong S.-L.,Chinese University of Hong Kong | Landale N.S.,Pennsylvania State University
Child Development | Year: 2012

Using data from the New Immigrant Survey, a study based on a nationally representative sample of legal immigrants, the present study extends prior research on the academic outcomes of immigrants' children by examining the roles of pre- and postmigration parental characteristics and the home environment. An analysis of 2,147 children aged 6-12 shows that parents' premigration education is more strongly associated with children's academic achievement than any other pre- or postmigration attribute. Premigration parental attributes account for the test score disadvantage of Mexican-origin children of legal immigrants, relative to their non-Latino counterparts. The findings reveal continuities and discontinuities in parental socioeconomic status and demonstrate that what parents bring to the United States and their experiences after arrival influence children's academic achievement. © 2012 Society for Research in Child Development, Inc. Source


Yang C.,Tsinghua University | Wong C.P.,Georgia Institute of Technology | Wong C.P.,Chinese University of Hong Kong | Yuen M.M.F.,Hong Kong University of Science and Technology
Journal of Materials Chemistry C | Year: 2013

Enormous efforts have been made towards the next generation of flexible, low-cost, environmentally benign printed electronics. In this regard, advanced materials for the printed conductive lines and interconnects are of significant importance. To improve efficiency and effectiveness, for several decades, conductive fillers have been filled into dispersants, which lead to the so-called electrically conductive composites (ECCs), which are a key material to the printed electronics varying from substituting the traditional solders to finding new applications in the blooming field of flexible printed electronics. ECCs in various formulations have converged in the current efforts to develop platforms with the desired specifications of electrical and thermal conductance, mechanical strength, and others. This platform is highly versatile and valuable for the emerging novel electronic devices, which emphasize tailoring processing conditions to cater to the key functional materials to optimize outcomes. The properties obtained can facilitate decisions about modifications to treatment. Noble metal fillers, such as silver flakes, have long been studied as active fillers for the ECCs. Owing to the recent progress in nanotechnology and surface modifications, many new avenues have opened for them. By taking advantage of the well-developed surface chemistry of these materials, researchers are enhancing their electrical conductivity, which is essential for broader applications. In recent years, the advances of ECCs have benefited the development of the applications of optoelectronics, e-papers, electromagnetic shielding, clinical diagnosis, radio frequency devices, etc. Despite the various advantages that they can offer over the traditional technologies, their limitations, e.g. low electrical conductivity, poor impact strength, increased contact resistance at elevated temperatures and humidity aging, have been considered as the major obstacles. In this feature article, we introduce the surface engineering techniques of the conductive filler materials that we and others have developed, with an emphasis on how these techniques influence the performance of the ECCs, especially for the improvement of the filler-to-filler electron transfer in the resin dispersants, some of which have potentially been approaching the theoretical upper limit of what they can reach in electrical conductivity. We and others have developed a set of chemical and engineering methods to modify the conductive fillers, enabling tailor-made surface functionalities and charges. These features, in turn, can be harnessed to adjust the electrical property and reliability of the ECCs, and further, to cater to various novel printed electronics, based on e.g. low temperature processing conditions. © The Royal Society of Chemistry 2013. Source


Woo J.,Chinese University of Hong Kong
Current Opinion in Clinical Nutrition and Metabolic Care | Year: 2015

Purpose of review There is an increasing number of reports suggesting that indicators of obesity for the general adult population may need to be modified; that the magnitude of risk is attenuated or that adiposity may even be protective; and that additional adverse outcomes specific to older persons need to be considered. Finally, there are benefits and adverse effects of weight loss programmes for older persons. This article reviews publications addressing these issues from 2013 to March 2014.Recent findings BMI was not considered to be as good an indicator of obesity because of loss of muscle mass with age. Higher body weight seems to be protective among older persons with chronic diseases or geriatric syndromes. Increased adiposity together with decreased muscle mass (sarcopenic obesity) is associated with adverse outcomes, although there is no consensus regarding the definition. Intentional weight loss has health benefits but is accompanied by muscle and bone loss, and therefore programmes should include components to counteract these changes.Summary The magnitude of health risk associated with obesity is attenuated with age, and mild increase in adiposity may be beneficial for those who are frail and/or with chronic diseases. Weight loss programmes should include resistance exercises to counteract muscle loss. Copyright © Lippincott Williams & Wilkins. Source


Zhang H.W.,Chinese University of Hong Kong
Cochrane database of systematic reviews (Online) | Year: 2012

Tianma Gouteng Yin Formula (TGYF) is widely used to treat hypertension-related symptoms in clinical practice in East Asia. It has been shown to have a blood pressure lowering effect, reducing total cholesterol, improving clinical symptoms and quality of life, and preventing the occurrence of stroke in hypertensive patients. Understanding the effect of Tianma Gouteng Yin Formula on blood pressure, quality of life and cardiovascular risk factors could be valuable for the management of high blood pressure. To assess the efficacy and safety of Tianma Gouteng Yin Formula for treating primary hypertension compared to placebo or no treatment. English databases including Cochrane Central (CCTR), MEDLINE, EMBASE, AMED, CINAHL, IPA, and the Hypertension Group Specialised Register were searched up to July 2011. Chinese databases including Chinese Biomedical Database, TCMonline , Chinese Dissertation Database, CMAC and the Index to Chinese Periodical Literature were searched up to April 2010. Randomised and quasi-randomised controlled trials that compared TGYF with no treatment or placebo for primary hypertension. No study was identified which met the inclusion criteria for this review. No study was identified which met the inclusion criteria for this review. As no trials could be identified, no conclusions can be made about the role of TGYF in the treatment of primary hypertension. Well-designed randomized controlled studies need to be conducted and published. Source


Wang J.,Chinese University of Hong Kong | Wang J.,Shanghai JiaoTong University
IEEE Transactions on Neural Networks | Year: 2010

This paper presents a k-winners-take-all (kWTA) neural network with a single state variable and a hard-limiting activation function. First, following several kWTA problem formulations, related existing kWTA networks are reviewed. Then, the kWTA model model with a single state variable and a Heaviside step activation function is described and its global stability and finite-time convergence are proven with derived upper and lower bounds. In addition, the initial state estimation and a discrete-time version of the kWTA model are discussed. Furthermore, two selected applications to parallel sorting and rank-order filtering based on the kWTA model are discussed. Finally, simulation results show the effectiveness and performance of the kWTA model. © 2006 IEEE. Source


You J.,Chinese University of Hong Kong
Expert Opinion on Pharmacotherapy | Year: 2015

Antimicrobial stewardship programs (ASPs) are aimed to improve patient care and health care outcomes. It is encouraging to find ASP interventions to be cost-saving in many cost-minimization analyses in literature. Nevertheless, the cost-effectiveness of ASP interventions, measured in cost per quality-adjusted life-years, is less well-established. This Editorial aims to explore the barriers in assessing clinical effectiveness of ASPs and provide suggestions to conduct cost-effectiveness analysis of ASPs. © 2015 Informa UK, Ltd. Source


Ng C.S.H.,Chinese University of Hong Kong
Korean Journal of Thoracic and Cardiovascular Surgery | Year: 2014

Single-port video-assisted thoracic surgery (VATS) has slowly established itself as an alternate surgical approach for the treatment of an increasingly wide range of thoracic conditions. The potential benefits of fewer surgical incisions, better cosmesis, and less postoperative pain and paraesthesia have led to the technique's popularity worldwide. The limited single small incision through which the surgeon has to operate poses challenges that are slowly being addressed by improvements in instrument design. Of note, instruments and video-camera systems that are narrower and angulated have made single-port VATS major lung resection easier to perform and learn. In the future, we may see the development of subcostal or embryonic natural orifice translumenal endoscopic surgery access, evolution in anaesthesia strategies, and cross-discipline imaging-assisted lesion localization for single-port VATS procedures. © 2014. The Korean Society for Thoracic and Cardiovascular Surgery. Source


Gong S.,Nanyang Technological University | Wang P.,Nanyang Technological University | Huang J.,Chinese University of Hong Kong
IEEE Transactions on Wireless Communications | Year: 2013

The successful coexistence of secondary users (SUs) and primary users (PUs) in cognitive radio networks requires SUs to be spectrum aware and know which spectrum bands are occupied by PUs. Such awareness can be achieved in several ways, one of which is spectrum sensing. While existing spectrum sensing methods usually assume known distributions of the received primary signals, such an assumption is often too strong and unrealistic, and leads to unreliable detection performance in practical networks. In this paper, we design robust spectrum sensing algorithms under the distribution uncertainty of primary signals. After formulating the optimal sensing design as a robust optimization problem, we decompose it into a series of analytically tractable semi-definite programs, and propose an iterative algorithm to search the optimal decision threshold while maintaining the desirable false alarm probability during the iterations. Numerical results verify that our robust sensing algorithm improves the worst-case detection probability and reduces the system sensitivity on decision variables. © 2002-2012 IEEE. Source


Chen X.,Arizona State University | Huang J.,Chinese University of Hong Kong
IEEE Journal on Selected Areas in Communications | Year: 2013

According to FCC's ruling for white-space spectrum access, white-space devices are required to query a database to determine the spectrum availability. In this paper, we study the database-assisted distributed white-space access point (AP) network design. We first model the cooperative and non-cooperative channel selection problems among the APs as the system-wide throughput optimization and non-cooperative AP channel selection games, respectively, and design distributed AP channel selection algorithms that achieve system optimal point and Nash equilibrium, respectively. We then propose a state-based game formulation for the distributed AP association problem of the secondary users by taking the cost of mobility into account. We show that the state-based distributed AP association game has the finite improvement property, and design a distributed AP association algorithm that can converge to a state-based Nash equilibrium. Numerical results show that the algorithm is robust to the perturbation by secondary users' dynamical leaving and entering the system. © 1983-2012 IEEE. Source


Wong W.S.,Chinese University of Hong Kong | Baillieul J.,Boston University
IEEE Transactions on Automatic Control | Year: 2012

Recent papers have treated control communication complexity in the context of information-based, multiple agent control systems including nonlinear systems of the type that have been studied in connection with quantum information processing. The present paper continues this line of investigation into a class of two-agent distributed control systems in which the agents cooperate in order to realize common goals that are determined via independent actions undertaken individually by the agents. A basic assumption is that the actions taken are unknown in advance to the other agent. These goals can be conveniently summarized in the form of a target matrix, whose entries are computed by the control system responding to the choices of inputs made by the two agents. We show how to realize such target matrices for a broad class of systems that possess an input-output mapping that is bilinear. One can classify control-communication strategies, known as control protocols, according to the amount of information sharing occurring between the two agents. Protocols that assume no information sharing on the inputs that each agent selects and protocols that allow sufficient information sharing for identifying the common goals are the two extreme cases. Control protocols will also be evaluated and compared in terms of cost functionals given by integrated quadratic functions of the control inputs. The minimal control cost of the two classes of control protocols are analyzed and compared. The difference in the control costs between the two classes reflects an inherent trade-off between communication complexity and control cost. © 2012 IEEE. Source


Wu J.C.Y.,Chinese University of Hong Kong
Journal of Gastroenterology and Hepatology (Australia) | Year: 2011

Functional gastrointestinal disorder (FGID) is one of the commonest digestive diseases worldwide. Current evidence supports a bio-psycho-social pathophysiological model for FGID, which underscores the importance of psychological and social factors in development of FGID. Concomitant psychological disorders, which include anxiety, depression and somatization, have been shown to be associated with FGID in both specialist and community-based studies. This suggests that the association is genuine rather than biased observation in referral centers. Furthermore, psychological distress such as depression, anxiety and phobia are strongly correlated with severity of FGID symptoms. There are biologically plausible mechanisms that support the causal role of psychological disorders in FGID. Psychological distress, in particular anxiety, can induce aggravation of visceral hyperalgesia as well as hypervigilance in FGID patients. This leads to poorer quality of life and increased utilization of healthcare service in addition to worsening of symptoms. Despite the numerous reports on the potential therapeutic value of psychotropic agents and psychological intervention, the importance of screening for concomitant psychological disorder in FGID patients has not been fully recognized in daily practice. Most FGID patients tend to have very low awareness of their mood symptoms, which lead to delayed diagnosis, deterioration of disease and unnecessary investigations. Many of these patients may be reluctant to accept the diagnosis of concomitant psychological disorders and therefore a good doctor-patient rapport and therapeutic relationship are essential for management of these patients. © 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd. Source


Liao W.-C.,National Tsing Hua University | Chang T.-H.,National Tsing Hua University | Ma W.-K.,Chinese University of Hong Kong | Chi C.-Y.,National Tsing Hua University
IEEE Transactions on Signal Processing | Year: 2011

Secure transmission techniques have been receiving growing attention in recent years, as a viable, powerful alternative to blocking eavesdropping attempts in an open wireless medium. This paper proposes a secret transmit beamforming approach using a quality-of-service (QoS)-based perspective. Specifically, we establish design formulations that: i) constrain the maximum allowable signal-to-interference-and-noise ratios (SINRs) of the eavesdroppers, and that ii) provide the intended receiver with a satisfactory SINR through either a guaranteed SINR constraint or SINR maximization. The proposed designs incorporate a relatively new idea called artificial noise (AN), where a suitable amount of AN is added in the transmitted signal to confuse the eavesdroppers. Our designs advocate joint optimization of the transmit weights and AN spatial distribution in accordance with the channel state information (CSI) of the intended receiver and eavesdroppers. Our formulated design problems are shown to be NP-hard in general. We deal with this difficulty by using semidefinite relaxation (SDR), an approximation technique based on convex optimization. Interestingly, we prove that SDR can exactly solve the design problems for a practically representative class of problem instances; e.g., when the intended receiver's instantaneous CSI is known. Extensions to the colluding-eavesdropper scenario and the multi-intended-receiver scenario are also examined. Extensive simulation results illustrate that the proposed AN-aided designs can yield significant power savings or SINR enhancement compared to some other methods. © 2010 IEEE. Source


Chan H.L.Y.,Chinese University of Hong Kong
Journal of Gastroenterology and Hepatology (Australia) | Year: 2011

Advances in molecular biology technology in the last two decades have allowed detailed study of the viral mutations and genomic heterogeneity of hepatitis B virus (HBV). The first mutant discovered was precore stop codon mutation. It was reported in HBeAg negative patients and initially thought to associate with fulminant hepatitis. Subsequent studies have suggested that it is merely one of the mechanisms of losing HBeAg by the virus. Another mutation that can downregulate the production of HBeAg is the basal core promoter mutation, which is located in the X gene upstream of the precore region. Based on the configuration of codon 15 and the stability of the epsilon of the precore region, these two mutants will be differentially selected during the course of HBeAg seroconversion. The most common HBV genotypes in South East Asia are genotype B and C HBV. The higher hepatocellular carcinoma (HCC) risk of genotype C HBV has been confirmed by longitudinal studies in Hong Kong and Taiwan. One possible carcinogenic mechanism is its association with basal core promoter mutation, which has also been found to be a risk factor of HCC. Within genotype C HBV, subgenotype Cs is predominant in South East Asia and subgenotype Ce is predominant in East Asia. Subgenotype Ce HBV has been found to have the highest risk of HCC as compared with subgenotype Cs or genotype B HBV. The understanding of the carcinogenic mechanisms of these HBV strains may shed light into future therapeutics in the prevention and treatment of HBV related HCC. © 2010 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd. Source


He S.Y.,Chinese University of Hong Kong
Applied Geography | Year: 2013

Children's independent mobility in many urban areas in the United States has been in decline. This implies that children's out-of-home travel involves the company of adults more often than before. This need requires parents to seek ways to balance work-family life. This study examines the factors that influence a parent-child joint trip to school in dual-earner households, with special consideration given to parental work arrangements and location, which act as intra-household temporal and spatial constraints. The study is carried out in the five-county Los Angeles region, drawing from household travel diaries from the 2001 Southern California Association of Governments (SCAG) Post Census Regional Household Travel Survey. The results show that parental employment, especially the mother's, is a very important factor influencing the probability of a joint trip to school. In terms of temporal constraints, longer working hours will reduce the likelihood that a child will be escorted by its parents. However, the option of flexible work hours offsets the negative effect of long working hours by offering a higher degree of scheduling flexibility. In terms of spatial constraints, the closer the mother's workplace is to the school, the more likely it is that the child will be escorted by the parents. This research provides important evidence that a child's joint trip is heavily influenced by the parents' work schedule and location. The findings shed light on how the provision of certain employment policies and programs may affect joint trips to school. © 2013 Elsevier Ltd. Source


You J.H.,Chinese University of Hong Kong
Expert Opinion on Pharmacotherapy | Year: 2011

Introduction: The merit of applying pharmacogenomics in the induction phase of warfarin therapy for personalized dosing is controversial and highly dependent on its cost-effectiveness. Areas covered: Published studies on pharmacoeconomics of warfarin pharmacogenomic application are reviewed. A literature search was done using Medline and Embase covering the period 2000-2010. Decision tree and Markov modeling were the most frequently used methods in the reviewed reports. Studies incorporating clinical efficacy data of genotype-guided dosing algorithm had shown that warfarin pharmacogenomics would improve quality-adjusted life-years (QALYs) gained. Nevertheless, it was unlikely to be cost-effective for general patients. Influential factors to improve the cost-effectiveness included low genotyping cost, high effectiveness in improving anticoagulation control/event rate, and applying warfarin pharmacogenomics to patients with high bleeding risk or at practice sites with suboptimal management of anticoagulation control. Expert opinion: Warfarin pharmacogenomics would improve QALYs and could possibly be cost-effective in selected patient groups or practice sites. © 2011 Informa UK, Ltd. Source


Liang X.Y.,Chinese University of Hong Kong
Investigative ophthalmology & visual science | Year: 2012

differentiate the associations of exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) with the ARMS2/HTRA1 locus. The entire ARMS2 sequence was sequenced and HTRA1 rs11200638 genotyped in 568 unrelated Chinese individuals: 156 exudative AMD patients, 164 PCV patients, and 248 controls. A meta-analysis was performed to examine the effects of rs10490924 and rs11200638 at the ARMS2/HTRA1 locus in PCV. In total, 31 polymorphisms in ARMS2 were identified. Significant associations with both exudative AMD and PCV were observed in 11 of them and HTRA1 rs11200638, with different genotypic distributions between exudative AMD and PCV (P < 0.001). After adjusting for rs11200638, ARMS2 rs10490924 remained significantly associated with exudative AMD (P = 0.011), but not with PCV (P = 0.077). Meta-analysis showed consistent allelic associations of rs10490924 and rs11200638 with PCV in different study populations. There is a strong and consistent association of the ARMS2/HTRA1 locus with both exudative AMD and PCV, suggesting the two disorders share, at least partially, similar molecular mechanisms. Different effect sizes indicate the existence of additional genetic and environmental factors affecting them to different extents. Source


Leung N.,Alice Ho Miu Ling Nethersole Hospital | Leung N.,Chinese University of Hong Kong
Liver International | Year: 2011

HBeAg seropositivity is a marker for active viral replication. In the natural history of chronic hepatitis B infection, HBeAg marks the first two of the four phases, namely the immune tolerant phase and the immune clearance phase, and is associated with highly replicative activity of the hepatitis B virus (HBV). Most HBV consensus reports and guidelines recommend antiviral therapy if the immune clearance phase is prolonged and if there is evidence of significant necroinflammation and fibrosis. Two main types of antiviral agents have been approved for treating patients in the immune clearance phase: interferon and nucleos(t)ide analogues (NUCs). The endpoints of therapy are viral suppression with HBeAg seroconversion, undetectable serum HBV DNA, normalization of serum alanine transaminase and improvement in the histological necroinflammatory and fibrosis scores. The ultimate goal of therapy is to obtain clinical benefit for the patient by reducing complications including hepatocellular carcinoma (HCC). The choice between interferon-based immune modulators or NUCs that target the HBV DNA polymerase must be carefully weighed on an individual basis. Therapy with NUCs is often preferred by doctors and patients because it is easy to administer, with predictable efficacy and minimal side-effects. In specific patient subgroups such as those with decompensated disease, poor predictors of response or lack of response to interferon-based therapy and/or significant comorbidities that cannot tolerate interferon-induced side effects, NUCs therapy is the obvious choice. Entecavir and tenofovir are the treatments of choice because their efficacy and safety profile are better than lamivudine, adefovir and telbivudine. More importantly, there is a minimal risk of drug resistance during long-term therapy with these agents. © 2011 John Wiley & Sons A/S. Source


Wang Z.,Chinese University of Hong Kong
Cancer biology & therapy | Year: 2012

Dioscin has been shown to promote anticancer activity against several forms of cancers. However, its detailed molecular mechanisms have not been clearly clarified.In this study, we demonstrate that dioscin induces apoptosis in cancer cells through the induction of oxidative stress. Treatment with cancer cells in vitro with dioscin resulted in rapid generation of reactive oxygen species (ROS) and the induction of mitochondrial pathway apoptosis in human esophageal cancer cell line Kyse510. Inhibition of oxidative stress by the antioxidant N-acetylcysteine blocked the induction of apoptosis by dioscin, indicating that ROS generation is the primary mechanism responsible for the proapoptotic activity of dioscin. Proteomic analysis and protein gel blotting further revealed peroxiredoxins 1 and 6 (PRDX 1 and 6), which are implicated in ROS metabolism and apoptosis, were associated with the anticancer effects of dioscin. Meanwhile, overexpression of PRDX 1 and 6 significantly blocked the elevated ROS and apoptosis induced by dioscin. In conclusion, we suggest that PRDX1 and PRDX6 are key targets in the process of dioscin-induced apoptosis that involves intracellular elevated ROS. Source


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. Source


Griffiths S.M.,Chinese University of Hong Kong
Asia-Pacific Journal of Public Health | Year: 2010

Increasing affluence and changing lifestyles are resulting in a greater burden of noncommunicable diseases (NCDs) in China. The challenge of how to counter the rising rates of obesity associated with increasingly sedentary lifestyles and diets higher in fats and sugars as well as countering the persistent threat from high rates of tobacco smoking among men, including male doctors, need to be public health priorities within the rapidly developing economy of China. While promoting a healthier environment is one important element, the increasing rates of diabetes and hypertension throw into sharp relief the need not only for primary prevention but also for screening programs to detect and provide early treatment for these common diseases. There is an increasing need for an integrated response that emphasizes the key role the health system can play in preventing mortality and morbidity from NCDs. As such, this needs to be a priority within the health care reform agenda. © 2010 APJPH. Source


Wong D.S.-Y.,Chinese University of Hong Kong
Annals of Plastic Surgery | Year: 2014

The pelvic and perineal regions are affected by a heterogeneous spectrum of pathologies, many with a tendency to recur. Extensive mutilation carries physical, sexual, and psychological sequelae. Primary reconstruction reduces morbidity and shortens recovery. Modern management calls for a multidisciplinary approach. Not uncommonly, patients come with previous surgery and/or chemoirradiation. They may also be elderly and debilitated.The literature on reconstruction of the perineum can be confusing because knowledge has evolved by an accumulation of isolated short reports of individual methods. This led to the lack of a unifying basis for nomenclature and a failure to relate specific techniques to their roles in repairing particular types of defects. This article gives an overall summary of the approaches in a structured and rational manner.Defects of the external pelvis and perineal lining are usually amenable to coverage with local or regional fasciocutaneous flaps, if primary closure or skin graft is not appropriate. These flaps depend on the integrity of the vascular territories of the internal pudendal, the upper medial thigh plexus, or the descending branches of the inferior gluteal. The location and extent of the resection usually determine the requirements of the reconstruction and may dictate the choice of options.When defects are pelviperineal, particularly when the vagina needs to be reconstructed, myocutaneous flaps are of proven advantage in dealing with both the resurfacing as well as providing the bulk needed to fill the pelvic cavity after extensive resections. The rectus, gluteus, and gracilis are the best known options. Owing to the intrinsic limitations with the gracilis flap, the rectus and gluteus flaps have largely superseded its role in most situations. The rectus flap, in particular, provides good bulk as well as reliable skin.The use of muscle sparing flaps based on the perforator principle in suitable instances has increasingly been reported. The role of free tissue transfer, however, remains limited to isolated situations not amenable to current standard techniques.New and innovative reconstructive modifications keep appearing and larger scale series are needed for more evidence-based information on the outcomes achieved. Copyright © 2014 by Lippincott Williams &Wilkins. Source


Huang L.,Chinese University of Hong Kong
Journal of Vision | Year: 2010

A recent important debate in the field of visual working memory has focused on whether it represents a small set of highprecision representations (the "slot" model) or all items in parallel (the "resource" model). When faced with a large number of items, the slot model claims that high-precision representations of several items are stored and no information is retained about the other items, whereas the resource model claims that some imperfect information about each of the items can be stored. In this study, the observers tried to memorize and then recall six (out of eight possible) colors. The distribution of their scores (i.e., the number of correct responses) was modeled, and the empirical pattern of distribution fitted precisely with the prediction of the resource model but clearly differed from that of the slot model. Dependence analysis also revealed that the reports of items were approximately independent of each other, suggesting that all of the items were represented in parallel, as predicted by the resource model but not by the slot model. Overall, the data favored the resource model, not the slot model. © ARVO. Source


To investigate the factors associated with the uptake of influenza A/H1N1 vaccination by university students, and to examine the relationship between intention and actual vaccination. Prospective cohort study. A baseline survey was conducted among students at the Chinese University of Hong Kong in 2009 to collect data on demographics, pandemic risk perceptions and self-reported intention to be vaccinated in the future. A follow-up survey was conducted in 2011 using an online survey platform collecting information on actual vaccine uptake behaviour, and vaccine attitudes, knowledge and perceptions. Self-reported intention to be vaccinated in 2009 was significantly associated with actual vaccine acceptance. Vaccine perceptions (attitudes and knowledge) were found to be a better predictor of vaccine acceptance than disease risk perceptions. Being a medical or science student and receiving health advice about vaccination from a doctor or school-endorsed advertisement were also found to be predictors of vaccine acceptance. University students in Hong Kong were wary of the A/H1N1 vaccination campaign, as revealed by their low uptake rate and doubts about the vaccine. Knowledge of the pandemic and vaccine was high in this population, but feelings of susceptibility were low. The results indicate a need to provide tailored messages emphasizing the importance of vaccination and the efficacy of the vaccine in the future. Copyright © 2012 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved. Source


Reck M.,Airway Research Center North | Heigener D.F.,Airway Research Center North | Mok T.,Chinese University of Hong Kong | Soria J.-C.,Institute Gustave Roussy Villejuif | And 3 more authors.
The Lancet | Year: 2013

Non-small-cell lung cancer is one of the leading causes of deaths from cancer worldwide. Therefore, improvements in diagnostics and treatments are urgently needed. In this review, we will discuss the evolution of lung cancer staging towards more non-invasive, endoscopy-based, and image-based methods, and the development of stage-adapted treatment. A special focus will be placed on the role of novel surgical approaches and modern radiotherapy strategies for early stages of disease, the effect of multimodal treatment in locally advanced disease, and ongoing developments in the treatment of patients with metastatic disease. In particular, we will include an emphasis on targeted therapies, which are based on the assumption that a treatable driver mutation or gene rearrangement is present within the tumour. Finally, the position of lung cancer treatment on the pathway to personalised therapy will be discussed. © 2013 Elsevier Ltd. Source


Chen Y.,University of Southern California | Wang C.C.L.,Chinese University of Hong Kong
CAD Computer Aided Design | Year: 2011

Uniform offsetting is an important geometric operation for computer-aided design and manufacturing (CAD/CAM) applications such as rapid prototyping, NC machining, coordinate measuring machines, robot collision avoidance, and Hausdorff error calculation. We present a novel method for offsetting (grown and shrunk) a solid model by an arbitrary distance r. First, offset polygons are directly computed for each face, edge, and vertex of an input solid model. The computed polygonal meshes form a continuous boundary; however, such a boundary is invalid since there exist meshes that are closer to the original model than the given distance r as well as self-intersections. Based on the problematic polygonal meshes, we construct a well-structured point-based model, Layered Depth-Normal Image (LDNI), in three orthogonal directions. The accuracy of the generated point-based model can be controlled by setting the tessellation and sampling rates during the construction process. We then process all the sampling points in the model by using a set of point filters to delete all the invalid points. Based on the remaining points, we construct a two-manifold polygonal contour as the resulting offset boundary. Our method is general, simple and efficient. We report experimental results on a variety of CAD models and discuss various applications of the developed uniform offsetting method. © 2010 Elsevier Ltd. All rights reserved. Source


Lee A.L.,Chinese University of Hong Kong
Journal of Health Communication | Year: 2010

A popular perception holds that physicians prescribe requested drugs to patients influenced by mass mediated direct-to-consumer prescription drug advertising. The phenomenon poses a serious challenge to the two-step flow model, which emphasizes the influence of opinion leaders on their followers and their legitimating power over the informing power of the mass media. This study investigates a 2002 Food and Drug Administration (FDA) survey and finds that patients searching for drug information through mass and hybrid media in newspapers and magazines' small print, the Internet, and toll-free numbers are more likely to seek information through interpersonal communication channels like health care providers. Patients using small print, toll-free numbers, one's own physician, and other physicians are associated with influencing their physicians with various drug-requesting behaviors. But physicians only prescribe requested drugs to patients who are influenced by other health care providers, such as pharmacists and other physicians, not the mass media. The influence of expert opinion leaders of drugs is so strong that the patients even would switch from their own unyielding physicians who do not prescribe drugs as advised by the pharmacists. Physicians and patients all are influenced more by other expert opinion leaders of drugs than by the mass media and therefore still uphold the basic tenet of the two-step model. © 2010 Taylor & Francis Group, LLC. Source


Chan T.Y.K.,Chinese University of Hong Kong
Forensic Science International | Year: 2012

In vitro experiment using the modified Franz-type diffusion cell has demonstrated that the human skin is permeable to aconitine and mesaconitine. To characterise the risk of systemic toxicity following the topical applications of aconite tincture and raw aconite roots, relevant reports of percutaneous absorption of Aconitum alkaloids and aconite poisoning are reviewed. Published reports indicate that aconite tincture and raw aconite roots can be absorbed through the skin into systemic circulation to cause fatal and non-fatal aconite poisoning. Both aconite tincture and raw aconite roots contain very high concentrations of Aconitum alkaloids, which allow penetration of the stratum corneum along the diffusion gradient. The risk of systemic toxicity is even higher if Aconitum alkaloids are held in occlusive contact with the skin and the epidermis (stratum corneum) is already damaged. The public should be warned of the danger in using these topical aconite preparations and the risk of systemic toxicity following percutaneous absorption of Aconitum alkaloids. © 2012 Elsevier Ireland Ltd. Source


Huang J.,Chinese University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2011

This technical note further considers the synchronized output regulation problem of linear networked systems proposed in the paper by Xiang We first make the assumptions of the problem more accurate and present a more straightforward solution for the problem. Then we further point out that, under a different detectability condition, the problem can be solved by a decentralized control scheme. © 2006 IEEE. Source


Chan R.H.,Chinese University of Hong Kong | Ma J.,Macquarie University
IEEE Transactions on Image Processing | Year: 2012

Image restoration is a computationally intensive problem as a large number of pixel values have to be determined. Since the pixel values of digital images can attain only a finite number of values (e.g., 8-bit images can have only 256 gray levels), one would like to recover an image within some dynamic range. This leads to the imposition of box constraints on the pixel values. The traditional gradient projection methods for constrained optimization can be used to impose box constraints, but they may suffer from either slow convergence or repeated searching for active sets in each iteration. In this paper, we develop a new box-constrained multiplicative iterative (BCMI) algorithm for box-constrained image restoration. The BCMI algorithm just requires pixelwise updates in each iteration, and there is no need to invert any matrices. We give the convergence proof of this algorithm and apply it to total variation image restoration problems, where the observed blurry images contain Poisson, Gaussian, or salt-and-pepper noises. © 2012 IEEE. Source


Li D.,Dalian University of Technology | Han M.,Dalian University of Technology | Wang J.,Chinese University of Hong Kong
IEEE Transactions on Neural Networks and Learning Systems | Year: 2012

In this paper, a robust recurrent neural network is presented in a Bayesian framework based on echo state mechanisms. Since the new model is capable of handling outliers in the training data set, it is termed as a robust echo state network (RESN). The RESN inherits the basic idea of ESN learning in a Bayesian framework, but replaces the commonly used Gaussian distribution with a Laplace one, which is more robust to outliers, as the likelihood function of the model output. Moreover, the training of the RESN is facilitated by employing a bound optimization algorithm, based on which, a proper surrogate function is derived and the Laplace likelihood function is approximated by a Gaussian one, while remaining robust to outliers. It leads to an efficient method for estimating model parameters, which can be solved by using a Bayesian evidence procedure in a fully autonomous way. Experimental results show that the proposed method is robust in the presence of outliers and is superior to existing methods. © 2012 IEEE. Source


Xie Z.,Chinese University of Hong Kong
Science China Chemistry | Year: 2014

A research program was initiated to develop transition metal-mediated/ catalyzed synthetic methods for cage C-H/B-H functionalization of carboranes. A series of transition metal-o-carboryne (ocarboryne = 1,2-dehydro-o-carboran e) complexes were prepared as the formation of metallacyclopropane opens up the coordination sphere and creates ring strain, facilitating the reactions of MCcage bonds with electrophiles. The zirconium-o-carboryne species, generated in situ from Cp2Zr(μ-Cl)(μ-C2B 10H10) Li(OEt2)2, reacts with only 1 equivalent of alkyne, alkene or polar unsaturated organic substrates such as carbodiimides, nitriles, and azides to give thermodynamically very stable monoinsertion zirconacycles even in the presence of excess substrates. The search for applications of functionalized carboranes in many disciplines such as BNCT, electronics, catalysis, polymers, and nanomaterials is anticipated in the future. Source


Wu R.,Chinese University of Hong Kong
International Journal of Climatology | Year: 2014

This study investigates the year-to-year variations in aerosol optical depth (AOD) over South China and plausible connections with Hong Kong air quality changes. The inter-annual variability of AOD over South China is found to display a pronounced seasonal dependence, with the largest standard deviation in October and March, which is about two times of that in January. Hong Kong Air Pollution Index (API) also shows the largest variability in October and March. Analysis shows that the precipitation and circulation pattern associated with inter-annual variations of aerosol over South China is very different depending on the season. In October, precipitation decrease and anomalous lower-level wind convergence contribute to an increase in aerosol. In July, anomalous lower-level wind convergence contributes to an increase in both aerosol and precipitation. In March, the aerosol change has no obvious statistical relationship with local precipitation change, and the transport by anomalous winds appears to be a main factor for aerosol variations. The link between year-to-year changes in Hong Kong air quality and South China aerosol displays a strong seasonality. While the air quality change in Hong Kong is associated with regional aerosol, precipitation, and wind changes over South China in October and July, the air quality change in March appears to be related to local factors. The link of Hong Kong air quality to regional precipitation changes over South China tends to be opposite in October and July. This study points out the necessity of distinguishing the individual seasons when addressing the year-to-year changes in aerosol and air quality. The seasonal dependence of the aerosol-precipitation relationship may include the effects of the mean state, the meteorological condition, and the role of atmospheric circulation. © 2014 Royal Meteorological Society. Source


Mo P.K.H.,Chinese University of Hong Kong | Coulson N.S.,University of Nottingham
Patient Education and Counseling | Year: 2013

Objective: The Internet provides an opportunity for individuals with HIV/AIDS to obtain support and information in a timely and convenient manner. The present study examines the psychological effects of online support group use for individuals living with HIV/AIDS. Methods: A total of 340 HIV positive online support group users completed an online survey. Results: Results from structural equation modeling showed that individuals with higher levels of online support group participation had higher levels of empowering processes, which in turn, had higher levels of optimism toward life. Optimism was related to lower levels of loneliness and depression while loneliness was also related to higher levels of depression. Conclusion: The findings suggest that participants with higher levels of online support group participation had better psychological health than those with lower levels of participation. Practice implications: Findings suggest that the use of online support groups could be promoted to individuals with HIV/AIDS. Healthcare professionals should work to increase the motivation and confidence patients have in using online support groups. Health education should also be provided to patients with HIV/AIDS so to improve their skills and literacy in using online support groups. © 2013 Elsevier Ireland Ltd. Source


Shao M.-W.,Qingdao Technological University | Leung Y.,Chinese University of Hong Kong | Wu W.-Z.,Zhejiang Ocean University
International Journal of Approximate Reasoning | Year: 2014

In this paper, we introduce the notion of formal decision context as an extension of formal contexts by employing the notion of decision information table. We use formal concept analysis to formulate an approach to extract "if-then" rule from formal decision contexts. We also construct a knowledge-lossless method for complexity reduction in formal decision contexts so that the maximum rules extracted from the reduced formal decision contexts are identical to that extracted from the initial decision formal contexts. More specifically, we develop the discernibility matrix and the discernibility function in formal decision contexts to compute all of the attribute reductions without loss of knowledge. © 2013 Elsevier Inc. All rights reserved. Source


Lo Y.M.D.,Chinese University of Hong Kong
Clinical Chemistry and Laboratory Medicine | Year: 2012

Fetal DNA is present at an approximate mean fractional concentration of 10 % in the plasma of pregnant women. The detection of paternally-inherited DNA sequences that are absent in the maternal genome, e.g., Y chromosomal sequences for fetal sexing and the RHD gene for blood group genotyping, is well established. The recent emergence of single molecule counting technologies, such as digital polymerase chain reaction and massively parallel sequencing has allowed circulating fetal DNA to be used for the non-invasive prenatal diagnosis of fetal chromosomal aneuploidies and monogenic diseases. With large scale clinical validation and further reduction in costs, it is expected that the analysis of circulating fetal DNA will play an increasingly important role in the future practice of prenatal diagnosis. © 2012 by Walter de Gruyter •Berlin • Boston. Source


Li Z.J.,Chinese University of Hong Kong
Journal of translational medicine | Year: 2012

Tumor vasculature expresses a distinct set of molecule signatures on the endothelial cell surface different from the resting blood vessels of other organs and tissues in the body. This makes them an attractive target for cancer therapy and molecular imaging. The current technology using the in vivo phage display biopanning allows us to quickly isolate and identify peptides potentially homing to various tumor blood vessels. Tumor-homing peptides in conjugation with chemotherapeutic drugs or imaging contrast have been extensively tested in various preclinical and clinical studies. These tumor-homing peptides have valuable potential as targeting probes for tumor molecular imaging and drug delivery. In this review, we summarize the recent advances about the applications of tumor-homing peptides selected by in vivo phage display library screening against tumor vasculature. We also introduce the characteristics of the latest discovered tumor-penetrating peptides in their potential clinical applications. Source


Wise H.,Chinese University of Hong Kong
Journal of Molecular Signaling | Year: 2012

Alternative splicing of G protein-coupled receptor (GPCR) genes greatly increases the total number of receptor isoforms which may be expressed in a cell-dependent and time-dependent manner. This increased diversity of cell signaling options caused by the generation of splice variants is further enhanced by receptor dimerization. When alternative splicing generates highly truncated GPCRs with less than seven transmembrane (TM) domains, the predominant effect in vitro is that of a dominant-negative mutation associated with the retention of the wild-type receptor in the endoplasmic reticulum (ER). For constitutively active (agonist-independent) GPCRs, their attenuated expression on the cell surface, and consequent decreased basal activity due to the dominant-negative effect of truncated splice variants, has pathological consequences. Truncated splice variants may conversely offer protection from disease when expression of co-receptors for binding of infectious agents to cells is attenuated due to ER retention of the wild-type co-receptor. In this review, we will see that GPCRs retained in the ER can still be functionally active but also that highly truncated GPCRs may also be functionally active. Although rare, some truncated splice variants still bind ligand and activate cell signaling responses. More importantly, by forming heterodimers with full-length GPCRs, some truncated splice variants also provide opportunities to generate receptor complexes with unique pharmacological properties. So, instead of assuming that highly truncated GPCRs are associated with faulty transcription processes, it is time to reassess their potential benefit to the host organism. © 2012 Wise; licensee BioMed Central Ltd. Source


Boute A.,Chinese University of Hong Kong
Renewable and Sustainable Energy Reviews | Year: 2016

Electricity supply in remote areas of the Russian territory is heavily dependent on diesel sources. Diesel generation imposes an important economic and social burden on the local population, besides the environmental impact of greenhouse gas emissions, black carbon and oil spills. Switching to renewable energy could reduce the current economic, social and environmental cost of electricity supply in Russia's remote areas. The objective of this paper is to review Russia's off-grid renewable energy policy by focusing on the promotion of wind- and solar-diesel hybrid energy in the Russian Arctic. Taking a mainly regulatory perspective, this paper identifies existing barriers to the development of hybrid renewable-diesel investments. Building further on the international experience with the promotion of renewable energy in Arctic climates (e.g., in Alaska and Canada), this paper tests the feasibility of alternative 'best practice' mechanisms to support off-grid renewable energy in Russia. © 2016 Elsevier Ltd. All rights reserved. Source


Chan M.H.,Chinese University of Hong Kong
Monthly Notices of the Royal Astronomical Society | Year: 2013

Recent observations in galaxies and clusters indicate that dark matter density profiles exhibit core-like structures which contradict the numerical simulation results of collisionless cold dark matter. The idea of self-interacting cold dark matter (SICDM) has been invoked to solve the discrepancies between the observations and numerical simulations. In this paper. 1 derive some important scaling relations in galaxies and clusters by using the long-range SICDM model These scaling relations give good agreement with the empirical fittings from observational data in galaxies and clusters if the dark matter particles are only slightly self-interacting. Also there may exist a universal critical optical depth τc that characterizes the core-like structures These results generally support the idea of the SICDM to tackle the long-lasting dark matter problem. © 2013 The Authors. Source


Poon C.H.,Chinese University of Hong Kong
The British journal of nutrition | Year: 2013

Exposure to environmental toxicants or exogenous oestrogen increases the risk of cancer. Some toxicants such as polycyclic aromatic hydrocarbons (PAH) undergo biotransformation to become genotoxic agents. Cytochrome p450 (CYP) 1B1 is an enzyme catalysing this transformation. Consumption of fruit and vegetables is considered to be protective against carcinogenesis, and naringenin can be found abundantly in citrus fruits. In the present study, the effect of naringenin on the regulation of CYP1B1 was investigated in MCF-7 cells. Enzyme inhibition assays revealed that naringenin inhibited CYP1B1 at or above 5 μm but not CYP1A1 activity. Quantitative PCR analysis also demonstrated that 1 μm-naringenin reduced CYP1B1 mRNA expression induced by 7,12-dimethylbenz(α)anthracene (DMBA). Further study illustrated that the suppression was at the transcriptional level. Since previous studies have shown that oestrogen response element (ERE) and xenobiotic-responsive element (XRE) are functional binding sequences in the promoter region of CYP1B1, interference of DNA binding on these two elements was pursued. Employing reporter gene assays as well as the electromobility shift assay, we verified that naringenin counteracted DMBA-induced XRE binding at - 1675. These results supported the notion that fruit consumption could be a protective measure against PAH biotransformation. Source


Tse G.M.,Chinese University of Hong Kong | Tan P.-H.,Singapore General Hospital
Breast Cancer Research and Treatment | Year: 2010

Fine needle aspiration cytology (FNAC) and core needle biopsy (CNB) are widely used in diagnosing breast lesions, with both achieving high sensitivity and specificity. Whether FNAC or CNB is better remains highly controversial. In this review, the advantages and disadvantages of each of these methods are discussed, especially in relation to specific problematic groups of breast lesions. In general, CNB has a slight advantage with lower inadequate and suspicious rates, allowing easier grade assessment and ancillary testings (hormome receptors, HER2) in cases of cancers. FNAC cannot reliably predict invasion in a malignant aspirate, whereas CNB, although useful in confirming invasion in carcinomas, has a much lower efficacy in predicting invasion when only in situ carcinoma is detected. The other problematic areas are papillary breast lesions and fibroepithelial lesions, notably phyllodes tumors. In papillary lesions, FNAC diagnosis is inaccurate, but with CNB, one can confidently diagnose papillary lesion, although there is still significant false positive and false negative rates, even with immunohistochemistry. For fibroepithelial lesions, using either FNAC or CNB to differentiate between a phyllodes tumor from fibroadenoma is also inaccurate. As management of breast diseases necessitates the triple approach (clinical, imaging and pathological), an awareness of the limitations of these very useful diagnostic modalities by all specialists is prudent, especially when dealing with these specific groups of breast lesions. © 2010 Springer Science+Business Media, LLC. Source


Guldan G.S.,Chinese University of Hong Kong
Research in Sports Medicine | Year: 2010

Food intake and dietary behavior, along with physical activity, are key environmental determinants of both energy imbalance as well as achieving and maintaining a healthy weight. Increasingly globalized, obesogenic diets and dietary behaviors have created a mainly urban Asian childhood obesity epidemic, which, coupled with persistent undernutrition, present a complex double burden of malnutrition. Some dietary patterns associated with Asian childhood overweight include snacking and eating out; consumption of fast food, sweetened beverages, and excessive meat; unhealthy macronutrient energy proportions; and a preference for refined grains. Strong evidenced-based measures must be created or identified that can adjust these ongoing obesogenic dietary shifts in more healthful directions, targeting lower-income subgroups in some of these societies. Measures must sensitively prevent and control the complex, interrelated diet problems presenting the nutritional double burden that, if not controlled, may overwhelm societies and health systems, undermining further Asian progress in health and socioeconomic development. Copyright © Taylor & Francis Group, LLC. Source


Luo H.,Chinese University of Hong Kong
Frontiers in Microbiology | Year: 2015

The vast majority of environmental bacteria and archaea remain uncultivated, yet their genome sequences are rapidly becoming available through single cell sequencing technologies. Reconstructing metabolism is one common way to make use of genome sequences of ecologically important bacteria, but molecular evolutionary analysis is another approach that, while currently underused, can reveal important insights into the function of these uncultivated microbes in nature. Because genome sequences from single cells are often incomplete, metabolic reconstruction based on genome content can be compromised. However, this problem does not necessarily impede the use of phylogenomic and population genomic approaches that are based on patterns of polymorphisms and substitutions at nucleotide and amino acid sites. These approaches explore how various evolutionary forces act to assemble genetic diversity within and between lineages. In this mini-review, I present examples illustrating the benefits of analyzing single cell genomes using evolutionary approaches. © 2015 Luo. Source


Wang C.C.L.,Chinese University of Hong Kong
Computers in Industry | Year: 2011

Ray representation (Ray-rep) of a solid has been studied and used in the solid modeling community for many years because of its compactness and simplicity. This paper presents a parallel approach for mesh surface modeling from multi-material volume data using an extended Ray-rep as an intermediate, where every homogeneous region is enclosed by a set of two-manifold surface meshes on the resultant model. The approach consists of three major algorithms: firstly, an algorithm is developed to convert the given multi-material volumetric data into a Ray-rep for heterogeneous solid; secondly, filtering algorithm is exploited to process the rays of heterogeneous solid in parallel; and lastly, the adaptive mesh surfaces are generated from the Ray-rep through a dual-contouring like algorithm. Here the intermediate surfaces between two constituent materials can be directly extracted without building the volumetric mesh, and the manifold topology is preserved on each surface patch. Furthermore, general offset surface can be easily computed in this paradigm by designing a special parallel operator for the rays. © 2011 Elsevier B.V. All rights reserved. Source


Ho Chan M.,Chinese University of Hong Kong
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2015

Recently, an excess of GeV gamma-ray near the Galactic Centre has been reported. The spectrum obtained can be best fitted with the annihilation of 30-40 GeV dark matter particles through bb channel. In this Letter, I show that this annihilation model can also solve the mysteries of heating source in X-ray plasma and the unexpected high gamma-ray luminosity. The cross-section constrained by these observations give excellent agreements with both the predicted range by using Fermi-Large Area Telescope (LAT) data and the canonical thermal relic abundance cross-section. © 2015 The Authors. Source


Gu S.-J.,Chinese University of Hong Kong
International Journal of Modern Physics B | Year: 2010

We review the quantum fidelity approach to quantum phase transitions in a pedagogical manner. We try to relate all established but scattered results on the leading term of the fidelity into a systematic theoretical framework, which might provide an alternative paradigm for understanding quantum critical phenomena. The definition of the fidelity and the scaling behavior of its leading term, as well as their explicit applications to the one-dimensional transverse-field Ising model and the LipkinMeshkovGlick model, are introduced at the graduate-student level. Besides, we survey also other types of fidelity approach, such as the fidelity per site, reduced fidelity, thermal-state fidelity, operator fidelity, etc; as well as relevant works on the fidelity approach to quantum phase transitions occurring in various many-body systems. © 2010 World Scientific Publishing Company. Source


Ng E.,Chinese University of Hong Kong | Cheng V.,University of Cambridge
Energy and Buildings | Year: 2012

In sub-tropical city of Hong Kong where summer is hot and humid, the usage of outdoor spaces is often hindered due to thermal discomfort. In order to improve the thermal comfort of the outdoor environment and to make urban outdoor spaces delightful places for people to use and enjoy, better understanding of the thermal perception of people is needed. This paper presents the results of an outdoor thermal comfort study conducted in Hong Kong. The findings of the study reveal that air temperature, wind speed and solar radiation intensity are influential factors in determining the thermal sensation of people outdoor. Based on our analysis, the neutral physiological equivalent temperature (PET) in summer in Hong Kong is around 28 °C. Under shaded condition, a wind speed of 0.9-1.3 m/s is needed for a person in light clothing to achieve neutral thermal sensation in an urban environment. This understanding can contribute towards establishing wind performance standards for thermal comfort in hot and humid tropical and sub-tropical cities. © 2011 Elsevier B.V. All rights reserved. Source


Luo S.,CAS Shenzhen Institutes of Advanced Technology | Yu S.,CAS Shenzhen Institutes of Advanced Technology | Sun R.,CAS Shenzhen Institutes of Advanced Technology | Wong C.-P.,Chinese University of Hong Kong
ACS Applied Materials and Interfaces | Year: 2014

Nano Ag-deposited BaTiO3 (BT-Ag) hybrid particles usable as fillers for flexible polymeric composites to obtain high dielectric constant, low conductivity, and low dielectric loss were developed. BT-Ag hybrid particles were synthesized via a seed-mediated growing process by a redox reaction between silver nitrate and ethylene glycol. Nano Ag particles with a size less than 20 nm were discretely grown on the surface of the 100 nm BaTiO3. The similar lattice spacing of the (1 1 1) planes of BT and Ag led to the hetero-epitaxial growth of Ag on the BT surface. The thickness of the coherent interface was about 3 nm. The adhesion of Ag to BT efficiently prevented the continuous contact between Ag particles in the polyvinylidene fluoride (PVDF) matrix and suppressed the formation of the conducting path in the composite. As a result, with a filler loading of 43.4 vol %, the composite exhibited a dielectric constant (Dk) value of 94.3 and dielectric loss (tan δ) of 0.06 at 1 kHz. An even higher Dk value of 160 at 1 kHz (16 times larger than that of PVDF) was obtained when the content of BT-Ag was further increased, with low conductivity (σ < 10-5 S m -1) and low dielectric loss (tan δ = 0.11), demonstrating promising applications in the electronic devices. © 2013 American Chemical Society. Source


Qiu Z.,CAS Shanghai Institute of Organic Chemistry | Xie Z.,CAS Shanghai Institute of Organic Chemistry | Xie Z.,Chinese University of Hong Kong
Dalton Transactions | Year: 2014

o-Carboryne (1,2-dehydro-o-carborane) is a very reactive intermediate that can be generated in situ from 1-Br-2-Li-1,2-C2B10H 10, 1-I-2-Li-1,2-C2B10H10 or 1-Me3Si-2-[IPh(OAc)]-1,2-C2B10H10. It exists in two resonance forms, a bonding form vs. a biradical form. Each form demonstrates unique reactivity patterns. o-Carboryne can undergo various types of reactions such as [4 + 2]/[2 + 2] cycloaddition, ene reaction, hydrogen abstraction, and sp2/sp3 C-H bond insertion reaction with a broad spectrum of substrates including alkenes, alkynes, (hetero)aromatics, ethers, and ferrocenes. It is a very useful synthon for generating a variety of functionalized carboranes that have potential applications in medicine, materials science and organometallic/coordination chemistry. This perspective offers an overview of recent advances in this interesting research field. © 2014 The Royal Society of Chemistry. Source


Shi F.,Hefei University of Technology | Kong X.,Hefei University of Technology | Wang P.,Hefei University of Technology | Kong F.,Hefei University of Technology | And 3 more authors.
Nature Physics | Year: 2013

Single-molecule nuclear magnetic resonance is a current challenge in the field of magnetic resonance spectroscopy and has important applications in chemical analysis and quantum computing. Through decoherence measurements of nitrogen-vacancy centres under dynamical decoupling control, the sensing of a single 13 C nuclear spin at nanometre distance has recently been realized. A further step towards the ultimate goal of structure analysis of single molecules would be the direct measurement of the interactions within single nuclear-spin clusters. Here we sense a single 13 C- 13 C nuclear-spin dimer located about 1 €‰nm from the nitrogen-vacancy centre and characterize the interaction (1/4690 Hz) between the two nuclear spins. From the measured interaction we derive the spatial configuration of the dimer with atomic-scale resolution. These results indicate that, in combination with advanced material-surface engineering, central spin decoherence under dynamical decoupling control may be a useful probe for nuclear magnetic resonance single-molecule structure analysis. © 2014 Macmillan Publishers Limited. All rights reserved. Source


Yam J.C.S.,Chinese University of Hong Kong | Kwok A.K.H.,Hong Kong Sanatorium and Hospital
International Ophthalmology | Year: 2014

The objective of this study is to review the association between ultraviolet (UV) light and ocular diseases. The data are sourced from the literature search of Medline up to Nov 2012, and the extracted data from original articles, review papers, and book chapters were reviewed. There is a strong evidence that ultraviolet radiation (UVR) exposure is associated with the formation of eyelid malignancies [basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)], photokeratitis, climatic droplet keratopathy (CDK), pterygium, and cortical cataract. However, the evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, ocular surface squamous neoplasia (OSSN), and ocular melanoma remained limited. There is insufficient evidence to determine whether age-related macular degeneration (AMD) is related to UV exposure. It is now suggested that AMD is probably related to visible radiation especially blue light, rather than UV exposure. From the results, it was concluded that eyelid malignancies (BCC and SCC), photokeratitis, CDK, pterygium, and cortical cataract are strongly associated with UVR exposure. Evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, OSSN, and ocular melanoma remained limited. There is insufficient evidence to determine whether AMD is related to UV exposure. Simple behaviural changes, appropriate clothing, wearing hats, and UV blocking spectacles, sunglasses or contact lens are effective measures for UV protection. © 2013 Springer Science+Business Media Dordrecht. Source


Ng S.C.,Chinese University of Hong Kong
Journal of Gastroenterology and Hepatology (Australia) | Year: 2015

More than a decade ago, inflammatory bowel disease (IBD) is rare in Asia. Today, the importance of IBD in Asia is exemplified by its rapidly increasing incidence, complicated disease behavior, and substantial morbidity. In the first large-scale population-based epidemiologic study in Asia, the incidence of IBD varied from 0.60 to 3.44 per 100000. There has been a twofold to threefold increase in the incidence of IBD in several countries in Asia. Ulcerative colitis (UC) is more prevalent than Crohn's disease (CD), although CD incidence is rapidly increasing. A positive family history is much less common than in the West, as are extra-intestinal disease manifestations. Complicated and penetrating CD are common in Asia. These epidemiologic changes may relate to increased contact with the West, westernization of diet, improved hygiene, increasing antibiotics use, or changes in the gut microbiota. Asian patients with CD have altered gut microbiota compared with their healthy counterparts and Caucasian CD subjects. Mucosa-associated microbiota in IBD may differ geographically. In a population-based case-control study, breast-feeding, having pets, and better sanitary conditions were protective of IBD, suggesting that childhood environment plays an important role in modulating disease development. Genetic factors also differ between Asians and Caucasians. Nucleotide oligomerization domain-2 (NOD2) and autophagy variants were not associated with CD, but tumor necrosis factor superfamily gene-15 polymorphisms were strongly associated with CD in East Asians. Research in Asia, an area of rapidly changing IBD epidemiology, may lead to the discovery of critical etiologic factors that lead to the development of IBD. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd. Source


Woo J.,Chinese University of Hong Kong
Medical Clinics of North America | Year: 2011

With increasing life expectancy in developed and developing countries, maintaining health and function in old age has become an important goal, including avoidance or optimal control of chronic diseases; maintenance or retarding the decline of physical and cognitive function; optimizing psychological health; and maintaining independent functioning in tasks related to self-care and societal interaction. This article discusses all of those, as well as other components of successful aging such as social network and socioeconomic status. © 2011 Elsevier Inc. Source


Cheung N.W.T.,Chinese University of Hong Kong
Health and Place | Year: 2014

By comparing rural migrant and urban native adolescents in Guangzhou, the largest city in south China, this study investigated the relationships between social stress, social ties that link migrants to their host cities (local ties) and to their rural home communities (trans-local ties), and the migrants[U+05F3] mental well-being. Non-migration social stress was more strongly related to poor psychological health than to weak self-efficacy in both migrant and urban native adolescents. This pattern also applied to the effect of migration-specific assimilation stress on psychological health and self-efficacy in migrants. Social ties directly enhanced these two well-being outcomes in both samples, with the effects of trans-local and local ties proving equally potent among migrants. Trans-local ties were somewhat more useful for migrants in moderating the effects of non-migration social stress and assimilation stress, whereas the stress moderation function of social ties was less pronounced in urban natives. These findings extend the migration, network and social stress literature by identifying how local and trans-local ties protect mental health and mitigate stress in migrants. © 2014 Elsevier Ltd. Source


Zhang Y.J.,Chinese University of Hong Kong
IEEE Transactions on Wireless Communications | Year: 2010

Multi-packet reception (MPR) has been recognized as a powerful capacity-enhancement technique for randomaccess wireless local area networks (WLANs). As is common with all random access protocols, the wireless channel is often under-utilized in MPR WLANs. In this paper, we propose a novel multi-round contention random-access protocol to address this problem. This work complements the existing randomaccess methods that are based on single-round contention. In the proposed scheme, stations are given multiple chances to contend for the channel until there are a sufficient number of 'winning' stations that can share the MPR channel for data packet transmission. The key issue here is the identification of the optimal time to stop the contention process and start data transmission. The solution corresponds to finding a desired tradeoff between channel utilization and contention overhead. In this paper, we conduct a rigorous analysis to characterize the optimal strategy using the theory of optimal stopping. An interesting result is that the optimal stopping strategy is a simple threshold-based rule, which stops the contention process as soon as the total number of winning stations exceeds a certain threshold. Compared with the conventional single-round contention protocol, the multi-round contention scheme significantly enhances channel utilization when the MPR capability of the channel is small to medium. Meanwhile, the scheme automatically falls back to single-round contention when the MPR capability is very large, in which case the throughput penalty due to random access is already small even with singleround contention. © 2010 IEEE. Source


Liu Q.,Nanjing Southeast University | Guo Z.,University of North Carolina at Chapel Hill | Wang J.,Chinese University of Hong Kong
Neural Networks | Year: 2012

In this paper, a one-layer recurrent neural network is proposed for solving pseudoconvex optimization problems subject to linear equality and bound constraints. Compared with the existing neural networks for optimization (e.g., the projection neural networks), the proposed neural network is capable of solving more general pseudoconvex optimization problems with equality and bound constraints. Moreover, it is capable of solving constrained fractional programming problems as a special case. The convergence of the state variables of the proposed neural network to achieve solution optimality is guaranteed as long as the designed parameters in the model are larger than the derived lower bounds. Numerical examples with simulation results illustrate the effectiveness and characteristics of the proposed neural network. In addition, an application for dynamic portfolio optimization is discussed. © 2011 Elsevier Ltd. Source


Wu J.C.Y.,Chinese University of Hong Kong
Journal of Neurogastroenterology and Motility | Year: 2012

Functional gastrointestinal disorder (FGID) is one of the commonest digestive diseases worldwide and leads to significant morbidity and burden on healthcare resource. The putative bio-psycho-social pathophysiological model for FGID underscores the importance of psychological distress in the pathogenesis of FGID. Concomitant psychological disorders, notably anxiety and depressive disorders, are strongly associated with FGID and these psychological co-morbidities correlate with severity of FGID symptoms. Early life adversity such as sexual and physical abuse is more commonly reported in patients with FGID. There is mounting evidence showing that psychological disorders are commonly associated with abnormal central processing of visceral noxious stimuli. The possible causal link between psychological disorders and FGID involves functional abnormalities in various components of the brain-gut axis, which include hypothalamic-pituitary-adrenal system, sympathetic and parasympathetic nervous system, serotonergic and endocannabinoid systems. Moreover, recent studies have also shown that psychological distress may alter the systemic and gut immunity, which is increasingly recognized as a pathophysiologic feature of FGID. Psychotropic agent, in particular antidepressant, and psychological intervention such as cognitive behavioral therapy and meditation have been reported to be effective for alleviation of gastrointestinal symptoms and quality of life in FGID patients. Further studies are needed to evaluate the impact of early detection and management of co-morbid psychological disorders on the long-term clinical outcome and disease course of FGID. (J Neurogastroenterol Motil 2012;18:13-18). © 2012 The Korean Society of Neurogastroenterology and Motility. Source


To be fully exploitable in both formulation and manufacturing, a drug cocrystal needs to demonstrate simultaneous improvement of multiple key pharmaceutical properties over the pure drug crystal. The present work was aimed at investigating such feasibility with two model profen-nicotinamide cocrystals. Phase pure 1:1 ibuprofen-nicotinamide and flurbiprofen-nicotinamide cocrystals were prepared from solutions through rapid solvent removal using rotary evaporation,and characterized by DSC, PXRD, FTIR, phase solubility measurements, equilibrium moisture sorption analysis, dissolution testing and tabletability analysis. Temperature-composition phase diagrams constructed from DSC data for each profen and nicotinamide crystal revealed the characteristic melting point of the 1:1 cocrystal as well as the eutectic temperatures and compositions. Both cocrystals exhibited higher intrinsic dissolution rates than the corresponding profens. The cocrystals also sorbed less moisture and displayed considerably better tabletability than the individual profens and nicotinamide. Phase behaviors of 1:1 profen-nicotinamide cocrystal systems were delineated by constructing their temperature-composition phase diagrams. Cocrystallization with nicotinamide can simultaneously improve tableting behavior, hygroscopicity, and dissolution performance of ibuprofen and flurbiprofen. This could pave the way for further development of such cocrystal systems into consistent, stable, efficacious and readily manufacturable drug products. Source


Cui X.,Tsinghua University | Cui X.,Ohio State University | Zhou Q.,Chinese University of Hong Kong
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We show that spin-orbit coupling (SOC) significantly enhances the depletion of a homogeneous Bose-Einstein condensate in three dimensions. With decreasing anisotropy of the SOC, both the quantum and thermal depletion increase. In particular, different types of SOC give rise to qualitatively different dependences of the condensate depletion on microscopic variables including the scattering length, the strength of the SOC, and the temperature, which can be directly observed once these types of SOC are realized in experiments. Moreover, we point out that thermal depletion in three dimensions becomes logarithmically divergent at any given finite temperature when both the SOC and the interaction approach the isotropic limit. © 2013 American Physical Society. Source


Lu Y.,McGill University | Lau J.Y.W.,Chinese University of Hong Kong | Barkun A.,McGill University
British Journal of Surgery | Year: 2014

Background: The modern management of acute non-variceal upper gastrointestinal bleeding is centred on endoscopy, with recourse to interventional radiology and surgery in refractory cases. The appropriate use of intervention to optimize outcomes is reviewed. Methods: A literature search was undertaken of PubMed and the Cochrane Central Register of Controlled Trials between January 1990 and April 2013 using validated search terms (with restrictions) relevant to upper gastrointestinal bleeding. Results: Appropriate and adequate resuscitation, and risk stratification using validated scores should be initiated at diagnosis. Coagulopathy should be corrected along with blood transfusions, aiming for an international normalized ratio of less than 2·5 to proceed with possible endoscopic haemostasis and a haemoglobin level of 70 g/l (excluding patients with severe bleeding or ischaemia). Prokinetics and proton pump inhibitors (PPIs) can be administered while awaiting endoscopy, although they do not affect rebleeding, surgery or mortality rates. Endoscopic haemostasis using thermal or mechanical therapies alone or in combination with injection should be used in all patients with high-risk stigmata (Forrest I-IIb) within 24 h of presentation (possibly within 12 h if there is severe bleeding), followed by a 72-h intravenous infusion of PPI that has been shown to decrease further rebleeding, surgery and mortality. A second attempt at endoscopic haemostasis is generally made in patients with rebleeding. Uncontrolled bleeding should be treated with targeted or empirical transcatheter arterial embolization. Surgical intervention is required in the event of failure of endoscopic and radiological measures. Secondary PPI prophylaxis when indicated and Helicobacter pylori eradication are necessary to decrease recurrent bleeding, keeping in mind the increased false-negative testing rates in the setting of acute bleeding. Conclusion: An evidence-based approach with multidisciplinary collaboration is required to optimize outcomes of patients presenting with acute non-variceal upper gastrointestinal bleeding. © 2013 BJS Society Ltd. Source


Bogdanov A.,Chinese University of Hong Kong | Viola E.,Northeastern University
SIAM Journal on Computing | Year: 2010

We present a new approach to constructing pseudorandom generators that fool low- degree polynomials over finite fields, based on the Gowers norm. sUsing this approach, we obtain the following main constructions of explicitly computable generators G : Fs → Fn that fool polynomials over a finite field F: 1. a generator that fools degree-2 (i.e., quadratic) polyno mials to within error 1/n, with seed length s = 0(log n), 2. a generator that fools degree-3 (i.e., cubic) polynomials to within error ∈, with seed length s = O(log|F| n) + f (∈,F), where f depends only on ∈ and F (not on n), 3. assuming the "inverse conjecture for the Gowers norm," for every d a generator that fools degree-d polynomials to within error ∈, with seed length s = 0(d · log|F| n) + f (d,∈,F), where f depends only on d, ∈,and F (not on n). We stress that the results in (1) and (2) are unconditional, i.e., do not rely on any unproven assumption. Moreover, the results in (3) rely on a special case of the conjecture which may be easier to prove. Our generator for degree-d polynomials is the componentw ise sum of d generators for degree-1 polynomials (on independent seeds). Prior to our work, generators with logarithmic seed length were only known for degree-1 (i.e., linear) polynomials [J. Naor and M. Naor, SIAM J. Comput., 22 (1993), pp. 838-856]. In fact, over small fields such as F2 = {0, 1}, our results constitute the first progress on these problems since the long-standing generator by Luby, Veličković, and Wigderson [Deterministic approximate counting of depth-2 circuits, in Proceedings of the 2nd Israeli Symposium on Theoretical Computer Science (ISTCS), 1993, pp. 18-24], whose seed length is much bigger: s = exp (ω (√log n)), even for the case of degree-2 polynomials over 7Fdbl;2. © 2010 Society for Industrial and Applied Mathematics. Source


Trepo C.,Croix Rousse Hospital | Trepo C.,French Institute of Health and Medical Research | Chan H.L.Y.,Chinese University of Hong Kong | Lok A.,University of Michigan
The Lancet | Year: 2014

Hepatitis B virus infection is a major public health problem worldwide; roughly 30% of the world's population show serological evidence of current or past infection. Hepatitis B virus is a partly double-stranded DNA virus with several serological markers: HBsAg and anti-HBs, HBeAg and anti-HBe, and anti-HBc IgM and IgG. It is transmitted through contact with infected blood and semen. A safe and effective vaccine has been available since 1981, and, although variable, the implementation of universal vaccination in infants has resulted in a sharp decline in prevalence. Hepatitis B virus is not cytopathic; both liver damage and viral control - and therefore clinical outcome - depend on the complex interplay between virus replication and host immune response. Overall, as much as 40% of men and 15% of women with perinatally acquired hepatitis B virus infection will die of liver cirrhosis or hepatocellular carcinoma. In addition to decreasing hepatic inflammation, long-term antiviral treatment can reverse cirrhosis and reduce hepatocellular carcinoma. Development of new therapies that can improve HBsAg clearance and virological cure is warranted. © 2014 Elsevier Ltd. Source


Wong W.S.,Chinese University of Hong Kong
IEEE Transactions on Vehicular Technology | Year: 2014

In this paper, we examine the problem of designing and allocating transmission sequences to users in a mobile ad hoc network that has no spatial boundary. A basic tenet of the transmission sequence approach for addressing media access control (MAC) is that under normal operating conditions, there is no feedback-triggered retransmission. This obviously is a major departure from the Slotted-ALOHA or carrier-sense multiple-access (CSMA)-type approaches. While these traditional solutions enjoy excellent throughput performance, a fundamental drawback is that they are based on feedback information. For systems without a naturally defined central controller that can play the role of a base station, the task of providing feedback information could easily become unmanageable. This highlights the advantage of the feedback-free approach. A second advantage is the ability to handle unlimited spatial coverage. We propose in this paper a concept for MAC that is akin to frequency reuse. However, instead of reusing frequency, the new approach allows transmission sequences to be reused. A study of the transmission sequence approach against other approaches is conducted by comparing the minimal frame lengths that can guarantee the existence of conflict-free transmissions. © 2013 IEEE. Source


Zhou Q.,Chinese University of Hong Kong | Cui X.,Tsinghua University
Physical Review Letters | Year: 2013

Intensive theoretical studies have recently predicted that a Bose-Einstein condensate will exhibit a variety of novel properties if spin-orbit coupling is present. However, an unambiguous fact has also been pointed out: Rashba coupling destroys a condensate of noninteracting bosons even in high dimensions. Therefore, a conceptually important question arises as to whether or not a condensate exists in the presence of interaction and a general type of spin-orbit coupling. Here we show that interaction qualitatively changes the ground state of bosons under Rashba spin-orbit coupling. Any infinitesimal repulsion forces bosons either to condense at one or two momentum states or to form a superfragmented state that is a superposition of infinite numbers of fragmented condensates. The superfragmented state is unstable against the anisotropy of spin-orbit coupling in systems with large numbers of particles, leading to the revival of a condensate in current experiments. © 2013 American Physical Society. Source


Della Rocca G.J.,University of Missouri | Leung K.S.,Chinese University of Hong Kong | Pape H.-C.,RWTH Aachen
Journal of Orthopaedic Trauma | Year: 2011

Periprosthetic fractures are fractures that occur in association with an orthopaedic implant, most often used for joint arthroplasty or fracture fixation. They are associated with significant morbidity and increased mortality in some cases. The incidence of periprosthetic fractures appears to be increasing as a result of increasing patient longevity, more demanding activity levels that persist into advanced age for some patients, and as a result of the increasing rate of revision arthroplasty which accompanies increasing patient longevity. Implant, surgeon, and patient factors all contribute to the risk of periprosthetic fracture. In this review, we intend to discuss current trends in periprosthetic fractures and risk factors associated with their development in the joint arthroplasty and fracture patient. Copyright © 2011 by Lippincott Williams & Wilkins. Source


Chin K.J.,University of Toronto | Karmakar M.K.,Chinese University of Hong Kong | Peng P.,University of Toronto
Anesthesiology | Year: 2011

The role of ultrasound in central neuraxial blockade has been underappreciated, partly because of the relative efficacy of the landmark-guided technique and partly because of the perceived difficulty in imaging through the narrow acoustic windows produced by the bony framework of the spine. However, this also is the basis for the utility of ultrasound: an interlaminar window that permits passage of sound waves into the vertebral canal also will permit passage of a needle. In addition, ultrasound aids in identification of intervertebral levels, estimation of the depth to epidural and intrathecal spaces, and location of important landmarks, including the midline and interlaminar spaces. This can facilitate neuraxial blockade, particularly in patients with difficult surface anatomic landmarks. In this review article, the authors summarize the current literature, describe the key ultrasonographic views, and propose a systematic approach to ultrasound imaging for the performance of spinal and epidural anesthesia in the adult patient. Copyright © 2011, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins. Source


Chu D.,Chinese University of Hong Kong
First Monday | Year: 2010

This study addresses three research questions that aim to describe the media use patterns of young people in Hong Kong. In particular, four dimensions of media use are taken as preliminary indicators to determine whether young people fit the popular stereotype of active Internet users. The dimensions include their reasons for going online, their initiative for information management, their production of content, and their collaboration and sharing activities on the Internet. A self-administered semi-structured questionnaire was distributed to 649 sixth formers in 11 secondary schools in Hong Kong between December 2008 and February 2009. The survey found little support for popular claims that celebrate the active roles of participants in the new media culture. Despite growing up "digitally," the young people in this study did not demonstrate markedly different characteristics in their media use. Indeed, instead of making the most out of the new media environment as "prosumers," they remained passive consumers in most cases. These findings call for a more critical evaluation of terms such as "prosumption," and of assumptions about generational differences in media use. Source


Wang S.,Chinese University of Hong Kong
Molecular medicine (Cambridge, Mass.) | Year: 2012

Dapper homolog 1 (DACT1) is a disheveled partner in the planar cell polarity pathway. By using genome-wide promoter methylation screening, dapper homolog 1 (DACT1) was found to be frequently methylated in gastric cancer. We aim to clarify its epigenetic inactivation, biological function and clinical implication in gastric cancer. We demonstrated that DACT1 was silenced in 7 of 10 gastric cancer cell lines and in primary gastric cancers. Transcriptional gene silence of DACT1 was mainly regulated by promoter hypermethylation. Ectopic expression of DACT1 in silenced gastric cancer cell lines (AGS, BGC823 and MGC803) by stable transfection suppressed colony formation (P < 0.001), induced cell apoptosis (P < 0.01) and retarded tumorigenesis in nude mice (P < 0.001). The tumor suppressive effect of DACT1 was further confirmed by loss of DACT1 function experiment. The proapoptotic and antiproliferative effect by DACT1 was associated with inhibition of nuclear factor (NF)-κB activation and its downstream factors, including B-cell CLL/lymphoma-2, Bcl-X, interleukin-8 and tumor necrosis factor-α. Moreover, promoter methylation of DACT1 was detected in 29.3% (60/205) of primary gastric tumors. DACT1 methylation was significantly associated with tumor metastasis (P < 0.05), invasion (P < 0.05) and advanced tumor stage (P < 0.0005). These findings provided insight into the role of DACT1 as a novel functional tumor suppressor in gastric cancer through inhibiting NF-κB signaling pathway. Promoter methylation of DACT1 is associated with tumor aggressiveness. Source


Zhang M.,Chinese University of Hong Kong
Biopolymers | Year: 2010

Recently, we isolated and purified a neutral polysaccharide (PGN) from edible fungus Pleurotus geestanus. Its structure was characterized by a range of physical-chemical methods, including high performance anion exchange chromatography, uronic acid, and protein analyses, size exclusion chromatography with ultraviolet, refractive index and light scattering detectors, and nuclear magnetic resonance. Our results revealed that PGN is a novel β-(1→3)-D-glucan with glucose attached to every other sugar residues at Position 6 in the backbone. It has a degree of branching of 1/2. Such structure is different from typical β-(1→3)-D-glucans schizophyllan and lentinan in which DB is 1/3 and 2/5, respectively. Rheological study showed a very interesting melting behavior of PGN in water solution: heating PGN in water leads to two transitions, in the range of 8-12.5°C and 25-60°C, respectively. The melting behavior and conformational changes were characterized by rheometry, micro-differential scan calorimetry, atomic force microscopy, static and dynamic light scattering at different temperatures. The first heating-induced transition corresponds to the disintegration of polymer bundles into small helical clusters, resembling the heating-induced dissociation of SPG in water at 7°C; the second one might correspond to the dissociation of helical strands to individual chains. The ability of PGN to undergo a conformation/viscosity transition in water upon heating is very valuable to immobilize cells or enzymes or therapeutic DNA/RNA, which makes PGN a potentially useful biomaterial. © 2009 Wiley Periodicals, Inc. Source


Nair C.,Chinese University of Hong Kong
IEEE Transactions on Information Theory | Year: 2010

Motivated by a simple broadcast channel, we generalize the notions of a less noisy receiver and a more capable receiver to an essentially less noisy receiver and an essentially more capable receiver, respectively. We establish the capacity regions of these classes by borrowing on existing techniques; however, these new classes contain additional interesting classes of broadcast channels, including the BSC/BEC broadcast channel. We also establish the relationships between the new classes and the existing classes. © 2010 IEEE. Source


More than half the world's population lives in cities. In tropical and subtropical regions, the growth of mega and compact cities are on the rise. The urban climatic issues of heat, humidity, lack of daylight, solar access, and urban ventilation is of topical concern to urban planners and governments. This paper puts forward a notion that a well established view of the low impact of urban climate on planning may be due to the lack of planning on the part of urban climatologists. Overly detailed and precise meteorological information, and excessively sophisticated climatic explanations and knowledge presentation do not help planners; information overload makes planners feel discouraged and ill equipped. In this paper, the understanding of Hong Kong based on the scale of planned decision making is elaborated with examples. Urban climatic information must be presented sequentially to fit the hierarchal process of planning and land use decision making. For better transfer of knowledge and communication, 'prevailing' and 'criticality' should be observed; information overload must be avoided, and spatial information must be presented graphically whenever possible. Scholars have argued that instead of the need for precision and accuracy, most of the time planners need to make balanced and reasonable decisions. Simplicity is the key. Furthermore, the advent of rapid urbanisation in the age of climate change further endows urban climatologists the burden to develop appropriate and easy-to-understand urban climate knowledge for planners. Resolving something complicated into something simple for planners is the only way forward. © 2011 Royal Meteorological Society. Source


Peyer K.E.,ETH Zurich | Zhang L.,Chinese University of Hong Kong | Nelson B.J.,ETH Zurich
Nanoscale | Year: 2013

Microrobots have been proposed for future biomedical applications in which they are able to navigate in viscous fluidic environments. Nature has inspired numerous microrobotic locomotion designs, which are suitable for propulsion generation at low Reynolds numbers. This article reviews the various swimming methods with particular focus on helical propulsion inspired by E. coli bacteria. There are various magnetic actuation methods for biomimetic and non-biomimetic microrobots, such as rotating fields, oscillating fields, or field gradients. They can be categorized into force-driven or torque-driven actuation methods. Both approaches are reviewed and a previous publication has shown that torque-driven actuation scales better to the micro- and nano-scale than force-driven actuation. Finally, the implementation of swarm or multi-agent control is discussed. The use of multiple microrobots may be beneficial for in vivo as well as in vitro applications. Thus, the frequency-dependent behavior of helical microrobots is discussed and preliminary experimental results are presented showing the decoupling of an individual agent within a group of three microrobots. © 2013 The Royal Society of Chemistry. Source


Xiang Q.,Wuhan University of Technology | Yu J.,Wuhan University of Technology | Wong P.K.,Chinese University of Hong Kong
Journal of Colloid and Interface Science | Year: 2011

Hydroxyl radicals (OH) have been deemed to be the major active species during the photocatalytic oxidation reaction. In this study, OH produced on various semiconductor photocatalysts in aqueous solution under Xenon lamp irradiation was quantitatively investigated by the photoluminescence (PL) technique using coumarin (COU) as a probe molecule. The results indicated that the formation rate of OH on the surface of irradiated commercial Degussa P25 (P25) was much higher than that of other semiconductor. The pH values of the solution and phase structure of TiO2 significantly influenced the production rate of OH. The acidic pH environment of the solutions and bi-phase structure (anatase and rutile) of TiO2 were beneficial to enhancing the formation rate of OH. In addition, the formation rate of OH on anatase TiO2 and P25 was much faster than that of OH on the other semiconductors (such as rutile TiO2, ZnO, WO3, CdS, Bi2WO4 and BiOCl, etc.). A new concept " OH-index" was first proposed to compare photocatalytic activity of photocatalysts, which would provide new insight into the investigation of semiconductor photocatalysts. © 2011 Elsevier Inc. Source


Li P.K.T.,Chinese University of Hong Kong | Burdmann E.A.,University of Sao Paulo | Mehta R.L.,University of California at San Diego
Transplantation | Year: 2013

Acute kidney injury (AKI) is increasingly prevalent in developing and developed countries and is associated with severe morbidity and mortality. Most etiologies of AKI can be prevented by interventions at the individual, community, regional, and in-hospital levels. Effective measures must include community-wide efforts to increase an awareness of the devastating effects of AKI and provide guidance on preventive strategies, and early recognition and management. Efforts should be focused on minimizing the causes of AKI, increasing awareness of the importance of serial measurements of serum creatinine in high-risk patients, and documenting urine volume in acutely ill people to achieve early diagnosis; there is as yet no definitive role for alternative biomarkers. Protocols need to be developed to systematically manage prerenal conditions and specific infections. More accurate data about the true incidence and clinical impact of AKI will help raise the importance of the disease in the community and increase awareness of AKI by governments, the public, and general and family physicians and other health care professionals to help prevent the disease. Prevention is the key to avoid the heavy burden of mortality and morbidity associated with AKI. Copyright © 2013 by Lippincott Williams & Wilkins. Source


Behrman J.R.,University of Pennsylvania | Xiong Y.,Nanjing Southeast University | Zhang J.,Chinese University of Hong Kong
Social Science and Medicine | Year: 2015

Adult health outcomes and health behaviors are often associated with schooling. However, such associations do not necessarily imply that schooling has causal effects on health with the signs or magnitudes found in the cross-sectional associations. Schooling may be proxying for unobserved factors related to genetics and family background that directly affect both health and schooling. Recently several studies have used within-monozygotic (MZ) twins methods to control for unobserved factors shared by identical twins. Within-MZ estimates for developed countries are generally smaller than suggested by cross-sectional associations, consistent with positive correlations between unobserved factors that determine schooling and those that determine health. This study contributes new estimates of cross-sectional associations and within-MZ causal effects using the Chinese Adults Twins Survey, the first study of its type for developing countries. The cross-sectional estimates suggest that schooling is significantly associated with adult health-related behaviors (smoking, drinking, exercising) but not with own or spouse health outcomes (general health, mental health, overweight, chronic diseases). However, within-MZ-twins estimators change the estimates for approximately half of these health indicators, in one case declining in absolute magnitudes and becoming insignificant and in the other cases increasing in absolute magnitudes. Within-MZ estimates indicate significant pro-health effects for at least one of the indicators for own health (better mental health), own health-related behaviors (less smoking) and spouse health (less overweight). © 2014 Elsevier Ltd. Source


Xu A.J.,University of Minnesota | Schwarz N.,University of Southern California | Wyer R.S.,Chinese University of Hong Kong
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Hunger motivates people to consume food, for which finding and acquiring food is a prerequisite. We test whether the acquisition component spills over to nonfood objects: Are hungry people more likely to acquire objects that cannot satisfy their hunger? Five laboratory and field studies show that hunger increases the accessibility of acquisition-related concepts and the intention to acquire not only food but also nonfood objects. Moreover, people act on this intention and acquire more nonfood objects (e.g., binder clips) when they are hungry, both when these items are freely available and when they must be paid for. However, hunger does not influence how much they like nonfood objects. We conclude that a basic biologically based motivation can affect substantively unrelated behaviors that cannot satisfy the motivation. This presumably occurs because hunger renders acquisitionrelated concepts and behaviors more accessible, which influences decisions in situations to which they can be applied. Source


Long intergenic non-coding RNAs (lincRNAs) are emerging as a novel class of non-coding RNAs and potent gene regulators. High-throughput RNA-sequencing combined with de novo assembly promises quantity discovery of novel transcripts. However, the identification of lincRNAs from thousands of assembled transcripts is still challenging due to the difficulties of separating them from protein coding transcripts (PCTs). We have implemented iSeeRNA, a support vector machine (SVM)-based classifier for the identification of lincRNAs. iSeeRNA shows better performance compared to other software. A public available webserver for iSeeRNA is also provided for small size dataset. iSeeRNA demonstrates high prediction accuracy and runs several magnitudes faster than other similar programs. It can be integrated into the transcriptome data analysis pipelines or run as a web server, thus offering a valuable tool for lincRNA study. Source


Wang A.Y.-M.,University of Hong Kong | Sanderson J.E.,Chinese University of Hong Kong
American Journal of Kidney Diseases | Year: 2011

Heart failure is one of the most frequent cardiac complications in patients with end-stage renal disease receiving long-term hemodialysis or peritoneal dialysis and is associated strongly with a poor prognosis. Despite the significant morbidity and mortality associated with heart failure, there are very limited therapeutic options proved to prevent and treat heart failure in dialysis patients. This limitation largely reflects the paucity of adequately powered prospective randomized clinical trials that have examined the efficacy of different therapeutic options in long-term dialysis patients with heart failure. In this article, the second in a series discussing the management of heart failure in dialysis patients, current therapeutic options for heart failure in the maintenance dialysis population are reviewed and potential novel therapeutic options are discussed. © 2011 National Kidney Foundation, Inc. Source


Miao Q.,Chinese University of Hong Kong | Miao Q.,University of Hong Kong
Advanced Materials | Year: 2014

Introducing N atoms to the pentacene backbone leads to N-heteropentacenes, whose properties can be tuned by changing the number, position and valence state of N atoms in the pentacene backbone. With a rapid development in recent years, N-heteropentacenes and their derivatives have arisen as a new family of organic semiconductors with high performance in organic thin-film transistors (OTFTs). This article reviews the research efforts of developing N-heteropentacenes into organic semiconductors starting from 2003 with emphasis on the work of the author's group since 2009. The structure-property relationship and design rationale are highlighted based on an overview of reported organic semiconductors of N-heteropentacenes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Guo Z.,University of North Carolina at Chapel Hill | Liu Q.,Nanjing Southeast University | Wang J.,Chinese University of Hong Kong
IEEE Transactions on Neural Networks | Year: 2011

In this paper, a one-layer recurrent neural network is presented for solving pseudoconvex optimization problems subject to linear equality constraints. The global convergence of the neural network can be guaranteed even though the objective function is pseudoconvex. The finite-time state convergence to the feasible region defined by the equality constraints is also proved. In addition, global exponential convergence is proved when the objective function is strongly pseudoconvex on the feasible region. Simulation results on illustrative examples and application on chemical process data reconciliation are provided to demonstrate the effectiveness and characteristics of the neural network. © 2011 IEEE. Source


In this article I demonstrate the knowledge perceptions of and the preventive health behaviors toward the influenza A H1N1 pandemic, or human swine flu, among the chronic renal disease patients in Hong Kong. Based on ethnographic data from participant observation in a chronic renal disease patient self-help alliance and semistructured interviews with its 30 members, I demonstrate that the participants knowledge perceptions of and the adoption of the preventive health behaviors against H1N1 were greatly influenced by their past experiences of being stigmatized in the 2003 severe acute respiratory syndrome (SARS) outbreak. In addition, the past experiences in the SARS outbreak not only led the participants to remember their stigmatization experiences in this H1N1 pandemic, but also aroused the memory of the general Hong Kong population that chronic renal disease patients were dangerous and polluted, which could further contribute to their stigmatization in this H1N1 pandemic. © The Author(s) 2010. Source


Zhou S.X.,Chinese University of Hong Kong | Yu Y.,CITIC Securities Co.
Operations Research | Year: 2011

Acquisition of used products (cores) is central to the success of remanufacturing programs for companies. At the same time, dynamic pricing strategies have been adopted in various industries to better balance supply and customer demand. In this paper, we study the integration of these two aspects of operations together with inventory management for a production/remanufacturing firm. We develop a periodic-review single-product inventory system with price-dependent customer demand. The product return in each period is random but can be actively controlled by the firm's acquisition effort. The firm aims to maximize its total discounted profit over a finite planning horizon by implementing optimal production, remanufacturing, product acquisition, and pricing strategies. We first show that with an exogenous selling price, the optimal production-remanufacturing-disposal policy is simple and characterized by three state-independent parameters. The optimal acquisition effort is decreasing in the aggregate inventory level of serviceable product and cores. Nevertheless, when pricing is an endogenous decision, we find that the optimal policy becomes much more complicated, and its control parameters are state dependent. The optimal selling price is decreasing, whereas the optimal acquisition effort is increasing in the serviceable product inventory level, and both decisions decrease with the aggregate inventory level. © 2011 INFORMS. Source


Ngan Kee W.D.,Chinese University of Hong Kong
Current Opinion in Anaesthesiology | Year: 2010

Purpose of review: Hypotension during regional anaesthesia for caesarean section remains a common clinical problem, particularly for spinal anaesthesia. The purpose of this review is to evaluate recent research in this area with a focus on English language papers from the past 1-2 years. Recent findings: Risk factors for hypotension include increased sympathetic tone, increasing age, obesity, higher blocks and higher birthweight, but not multiple gestation. Methods aimed at countering effects of aortocaval compression do not reliably prevent hypotension. Intravenous crystalloid prehydration has poor efficacy, and focus has changed toward cohydration and use of colloids. Phenylephrine is established as a first-line vasopressor, although there are limited data from high-risk patients. Initial phenylephrine bolus dose requirement may be surprisingly large. Phenylephrine infusions can be conveniently titrated to maintain blood pressure and prevent maternal symptoms. Ephedrine crosses the placenta more than phenylephrine and direct fetal effects of ephedrine may explain associated depression of fetal pH and base excess. Conclusion: Recent research supports decreased use of crystalloid prehydration and ephedrine and increased use of cohydration, colloids, smaller spinal doses and phenylephrine. Further research is required to investigate these techniques in high-risk patients and to evaluate novel monitoring techniques. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins. Source


Ramachandran A.,India Diabetes Research Foundation And Dr A Ramachandrans Diabetes Hospitals | Wan Ma R.C.,Chinese University of Hong Kong | Snehalatha C.,India Diabetes Research Foundation And Dr A Ramachandrans Diabetes Hospitals
The Lancet | Year: 2010

Prevalence of type 2 diabetes has rapidly increased in native and migrant Asian populations. Diabetes develops at a younger age in Asian populations than in white populations, hence the morbidity and mortality associated with the disease and its complications are also common in young Asian people. The young age of these populations and the high rates of cardiovascular risk factors seen in Asian people substantially increase lifetime risk of cardiovascular disease. Several distinctive features are apparent in pathogenetic factors for diabetes and their thresholds in Asian populations. The economic burden due to diabetes at personal, societal, and national levels is huge. National strategies to raise public awareness about the disease and to improve standard of care and implementation of programmes for primary prevention are urgently needed. © 2010 Elsevier Ltd. All rights reserved. Source


Chang K.-C.,Tuberculosis and Chest Service | Yew W.-W.,Chinese University of Hong Kong | Tam C.-M.,Tuberculosis and Chest Service | Leung C.-C.,Tuberculosis and Chest Service
Antimicrobial Agents and Chemotherapy | Year: 2013

It is often necessary to includeWHOgroup 5 drugs in the treatment of extensively drug-resistant tuberculosis (XDR-TB) and fluoroquinolone-resistant multidrug-resistant tuberculosis (MDR-TB). As clinical evidence about the use of group 5 drugs is scarce, we conducted a systematic review using published individual patient data.Wesearched PubMed and OvidSP through 7 April 2013 for publications in English to assemble a cohort with fluoroquinolone-resistant MDR-TB treated with group 5 drugs. Favorable outcome was defined as sputum culture conversion, cure, or treatment completion in the absence of death, default, treatment failure, or relapse. A cohort of 194 patients was assembled from 20 articles involving 12 geographical regions. In descending order of frequency, linezolid was used in treatment of 162 (84%) patients, macrolides in 84 (43%), clofazimine in 65 (34%), amoxicillin with clavulanate in 56 (29%), thioridazine in 18 (9%), carbapenem in 16 (8%), and high-dose isoniazid in 16 (8%). Cohort analysis with robust Poisson regression models and random-effects meta-analysis similarly suggested that linezolid use significantly increased the probability (95% confidence interval) of favorable outcome by 57% (10% to 124%) and 55% (10% to 121%), respectively. Defining significant associations by risk ratios>1.2 or<0.9, neither cohort analysis nor meta-analysis demonstrated any significant add-on benefit from the use of other group 5 drugs with respect to outcome for patients treated with linezolid, although selection bias might have led to underestimation of their effects. Our findings substantiated the use of linezolid in the treatment of XDR-TB or fluoroquinolone-resistant MDR-TB and call for further studies to evaluate the roles of other group 5 drugs. Copyright © 2013, American Society for Microbiology. All Rights Reserved. Source


Gao J.,Shanghai JiaoTong University | Li D.,Chinese University of Hong Kong
Automatica | Year: 2012

We study in this paper the linear-quadratic (LQ) optimal control problem of discrete-time switched systems with a constant switching cost for both finite and infinite time horizons. We reduce these problems into an auxiliary problem, which is an LQ optimal switching control problem with a cardinality constraint on the total number of switchings. Based on the solution structure derived from the dynamic programming (DP) procedure, we develop a lower bounding scheme by exploiting the monotonicity of the Riccati difference equation. Integrating such a lower bounding scheme into a branch and bound (BnB) framework, we offer an efficient numerical solution scheme for the LQ switching control problem with switching cost. © 2012 Elsevier Ltd. All rights reserved. Source


Feng Y.,City University of Hong Kong | Chen Y.F.,Chinese University of Hong Kong
Operations Research | Year: 2011

This note considers a joint inventory-pricing control problem in an infinite-horizon periodic-review system. Demand in a period is random and depends on the posted price. Besides the holding and shortage costs, the system incurs inventoryreplenishment costs that consist of both variable and fixed components. At the beginning of each period, a joint inventory and pricing decision is made. Under the long-run average profit criterion, we show that an optimal policy exists within the class of so-called 4s1 S1p5 policies. This is established based on our algorithmic development, which also results in an algorithm for finding an optimal 4s1 S1p5 policy. Subject classifications: joint pricing and inventory control; setup cost; price dependent demand; stochastic inventory model. Area of review: Manufacturing, Service, and Supply Chain Operations. History: Received May 2003; revisions received May 2004, August 2005, July 2007, May 2009; accepted April 2010. © 2011 INFORMS. Source


Celermajer D.S.,University of Sydney | Chow C.K.,University of Sydney | Chow C.K.,George Institute for Global Health | Marijon E.,Paris Cardiovascular Research Center | And 2 more authors.
Journal of the American College of Cardiology | Year: 2012

Over the past decade or more, the prevalence of traditional risk factors for atherosclerotic cardiovascular diseases has been increasing in the major populous countries of the developing world, including China and India, with consequent increases in the rates of coronary and cerebrovascular events. Indeed, by 2020, cardiovascular diseases are predicted to be the major causes of morbidity and mortality in most developing nations around the world. Techniques for the early detection of arterial damage have provided important insights into disease patterns and pathogenesis and especially the effects of progressive urbanization on cardiovascular risk in these populations. Furthermore, certain other diseases affecting the cardiovascular system remain prevalent and important causes of cardiovascular morbidity and mortality in developing countries, including the cardiac effects of rheumatic heart disease and the vascular effects of malaria. Imaging and functional studies of early cardiovascular changes in those disease processes have also recently been published by various groups, allowing consideration of screening and early treatment opportunities. In this report, the authors review the prevalences and patterns of major cardiovascular diseases in the developing world, as well as potential opportunities provided by early disease detection. © 2012 American College of Cardiology Foundation. Source


Chen L.,Chinese University of Hong Kong | He S.,City University of Hong Kong | Zhang S.,University of Minnesota
Operations Research | Year: 2011

In this paper we develop tight bounds on the expected values of several risk measures that are of interest to us. This work is motivated by the robust optimization models arising from portfolio selection problems. Indeed, the whole paper is centered around robust portfolio models and solutions. The basic setting is to find a portfolio that maximizes (respectively, minimizes) the expected utility (respectively, disutility) values in the midst of infinitely many possible ambiguous distributions of the investment returns fitting the given mean and variance estimations. First, we show that the single-stage portfolio selection problem within this framework, whenever the disutility function is in the form of lower partial moments (LPM), or conditional value-at-risk (CVaR), or value-at-risk (VaR), can be solved analytically. The results lead to the solutions for single-stage robust portfolio selection models. Furthermore, the results also lead to a multistage adjustable robust optimization (ARO) solution when the disutility function is the second-order LPM. Exploring beyond the confines of convex optimization, we also consider the so-called S-shaped value function, which plays a key role in the prospect theory of Kahneman and Tversky. The nonrobust version of the problem is shown to be NP-hard in general. However, we present an efficient procedure for solving the robust counterpart of the same portfolio selection problem. In this particular case, the consideration of the robustness actually helps to reduce the computational complexity. Finally, we consider the situation whereby we have some additional information about the chance that a quadratic function of the random distribution reaches a certain threshold. That information helps to further reduce the ambiguity in the robust model. We show that the robust optimization problem in that case can be solved by means of semidefinite programming (SDP), if no more than two additional chance inequalities are to be incorporated. © 2011 INFORMS. Source


Luisier F.,Ecole Polytechnique Federale de Lausanne | Blu T.,Chinese University of Hong Kong | Unser M.,Ecole Polytechnique Federale de Lausanne
IEEE Transactions on Image Processing | Year: 2011

We propose a general methodology (PURE-LET) to design and optimize a wide class of transform-domain thresholding algorithms for denoising images corrupted by mixed PoissonGaussian noise. We express the denoising process as a linear expansion of thresholds (LET) that we optimize by relying on a purely data-adaptive unbiased estimate of the mean-squared error (MSE), derived in a non-Bayesian framework (PURE: PoissonGaussian unbiased risk estimate). We provide a practical approximation of this theoretical MSE estimate for the tractable optimization of arbitrary transform-domain thresholding. We then propose a pointwise estimator for undecimated filterbank transforms, which consists of subband-adaptive thresholding functions with signal-dependent thresholds that are globally optimized in the image domain. We finally demonstrate the potential of the proposed approach through extensive comparisons with state-of-the-art techniques that are specifically tailored to the estimation of Poisson intensities. We also present denoising results obtained on real images of low-count fluorescence microscopy. © 2011 IEEE. Source


Ng T.B.,Chinese University of Hong Kong
Biopolymers | Year: 2012

Lipid-transfer proteins (LTPs) are basic proteins found in abundance in higher plants. LTPs play lots of roles in plants such as participation in cutin formation, embryogenesis, defense reactions against phytopathogens, symbiosis, and the adaptation of plants to various environmental conditions. In addition, LTPs from field mustard and Chinese daffodil exhibit antiproliferative activity against human cancer cells. LTPs from chili pepper and coffee manifest inhibitory activity against fungi pathogenic to humans such as Candida species. The intent of this article is to review LTPs in the plant kingdom. Source


Yu S.,Chinese University of Hong Kong | Liang Y.,Nanjing Agricultural University
Cellular and Molecular Life Sciences | Year: 2012

During biosynthesis many membrane and secreted proteins are transported from the endoplasmic reticulum, through the Golgi and on to the plasma membrane in small transport vesicles. These transport vesicles have to undergo budding, movement, tethering, docking, and fusion at each organelle of the biosynthetic pathway. The transport protein particle (TRAPP) complex was initially identified as the tethering factor for endoplasmic reticulum (ER)-derived COPII vesicles, but the functions of TRAPP may extend to other areas of biology. Three forms of TRAPP complexes have been discovered to date, and recent advances in research have provided new insights on the structures and functions of TRAPP. Here we provide a comprehensive review of the recent findings in TRAPP biology. © Springer Basel AG 2012. Source


Urigen J.A.,Imperial College London | Blu T.,Chinese University of Hong Kong | Dragotti P.L.,Imperial College London
IEEE Transactions on Signal Processing | Year: 2013

This paper addresses the problem of sampling non-bandlimited signals within the Finite Rate of Innovation (FRI) setting. We had previously shown that, by using sampling kernels whose integer span contains specific exponentials (generalized Strang-Fix conditions), it is possible to devise non-iterative, fast reconstruction algorithms from very low-rate samples. Yet, the accuracy and sensitivity to noise of these algorithms is highly dependent on these exponential reproducing kernels-actually, on the exponentials that they reproduce. Hence, our first contribution here is to provide clear guidelines on how to choose the sampling kernels optimally, in such a way that the reconstruction quality is maximized in the presence of noise. The optimality of these kernels is validated by comparing with Cramér-Rao's lower bounds (CRB). Our second contribution is to relax the exact exponential reproduction requirement. Instead, we demonstrate that arbitrary sampling kernels can reproduce the 'best' exponentials within quite a high accuracy in general, and that applying the exact FRI algorithms in this approximate context results in near-optimal reconstruction accuracy for practical noise levels. Essentially, we propose a universal extension of the FRI approach to arbitrary sampling kernels. Numerical results checked against the CRB validate the various contributions of the paper and in particular outline the ability of arbitrary sampling kernels to be used in FRI algorithms. © 2013 IEEE. Source


Lin L.-M.,Chinese University of Hong Kong
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Deconfined quark matter may exist in a crystalline color-superconducting phase in the interiors of compact stars. In this paper, we study the torsional oscillations of compact stars featuring a crystalline color-superconducting quark-matter core in general relativity. Depending on the size of the crystalline core and the value of the gap parameter Δ, we find that the frequencies of the torsional oscillation modes can range from a few hundred hertz to a few kilohertz for our canonical 1.4M⊙ compact star models. We have also studied the prospect for detecting the gravitational-wave signals emitted from these modes in a pulsar glitch event. Assuming that at least 10% of the energy released in a Vela glitch can be channeled to the oscillation modes, we find that the Einstein Telescope should be able to detect these signals in quite general situations. Furthermore, if the size of the crystalline core is comparable to the stellar radius and the gap parameter is relatively small at Δ∼5 MeV, the signal-to-noise ratio for Advanced LIGO could reach ∼10 for a Vela glitch. Our optimistic results suggest that we might already be able to probe the nature of crystalline color-superconducting quark matter with the second-generation gravitational-wave detectors when they come online in the next few years. © 2013 American Physical Society. Source


Wang X.,Chinese University of Hong Kong
Pattern Recognition Letters | Year: 2013

Intelligent multi-camera video surveillance is a multidisciplinary field related to computer vision, pattern recognition, signal processing, communication, embedded computing and image sensors. This paper reviews the recent development of relevant technologies from the perspectives of computer vision and pattern recognition. The covered topics include multi-camera calibration, computing the topology of camera networks, multi-camera tracking, object re-identification, multi-camera activity analysis and cooperative video surveillance both with active and static cameras. Detailed descriptions of their technical challenges and comparison of different solutions are provided. It emphasizes the connection and integration of different modules in various environments and application scenarios. According to the most recent works, some problems can be jointly solved in order to improve the efficiency and accuracy. With the fast development of surveillance systems, the scales and complexities of camera networks are increasing and the monitored environments are becoming more and more complicated and crowded. This paper discusses how to face these emerging challenges. © 2012 Elsevier B.V. All rights reserved. Source


Ma R.C.W.,Hong Kong Institute of Diabetes and Obesity | Ma R.C.W.,Chinese University of Hong Kong | Lin X.,CAS Shanghai Institutes for Biological Sciences | Jia W.,Shanghai JiaoTong University
The Lancet Global Health | Year: 2014

The prevalence of diabetes in China has increased substantially over recent decades, with more than 100 million people estimated to be affected by the disease presently. During this period there has been an increase in the rates of obesity and a reduction in physical activity. Many of the changes in lifestyle and diet are a result of increased economic development and urbanisation. In addition to an increasingly westernised diet, the traditional Chinese diet also plays a part, with the quantity and quality of rice intake linked to the risk of type 2 diabetes. Familial factors including inherited genetic variants are important, although differences in the genetic architecture suggest a different combination of genetic variants could be most relevant in Chinese when compared with Europeans. Recent advances have also emphasised the role of early life factors in the epidemic of diabetes and non-communicable diseases: maternal undernutrition, maternal obesity, and gestational diabetes are all linked to increased risk of diabetes in offspring. A mismatch between developmentally programmed biology and the modern environment is relevant for countries like China where there has been rapid economic transformation. Multisectoral efforts to address the risks will be needed at different stages throughout the lifecourse to reduce the burden of diabetes. © 2014 Elsevier Ltd. Source


Xu L.,Chinese University of Hong Kong
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

We study the instability development during a viscous liquid drop impacting a smooth substrate, using high-speed photography. The onset time of the instability highly depends on the surrounding air pressure and the liquid viscosity: it decreases with air pressure with the power of minus two, and increases linearly with the liquid viscosity. From the real-time dynamics measurements, we construct a model which compares the destabilizing stress from air with the stabilizing stress from liquid viscosity. Under this model, our experimental results indicate that at the instability onset time, the two stresses balance each other. This model also illustrates the different mechanisms for the inviscid and viscous regimes previously observed: the inviscid regime is stabilized by the surface tension and the viscous regime is stabilized by the liquid viscosity. © 2010 The American Physical Society. Source


Background: The HIV prevalence and incidence among men who have sex with men (MSM) are high. Unprotected anal intercourse (UAI) with male regular partners (RP) is an important but under-emphasized risk behavior. The current study aimed to describe the prevalence of UAI with regular partner and the associated multi-dimensional factors with UAI among MSM in Hong Kong, China.Methods: Respondent Driven Sampling method was used to recruit participants. A total of 285 participants were recruited, of whom 211 (75.1%) had had anal sex with RP in the last six months and their data were analyzed in this report. Weighed data were presented and logistic regression methods were fit.Results: Participants' high risk behaviors in the last six months included high prevalence of having had UAI with RP (45.8%), having had non-regular male sex partners (NRP: 27.3%) and UAI with such partners (18.9%). Adjusted for socio-demographic variables, factors associated with UAI with RP included: 1) substances use prior to having anal sex (65.7% versus 43.8%; AOR =2.36; 95% CI =1.07-5.18), 2) worry that condom use symbolizes mistrust (67.9% versus 44.3%; AOR = 2.91; 95% CI =1.19-7.10), 3) a lower perceived degree of the RP's acceptance of condom use (91.7% versus 38.3%; AOR = 22.70; 95% CI =6.20-83.10), and 4) a higher level of impulsivity (61.1% versus 35.0%; AOR =4.02; 95% CI = 1.62-9.97). Two of these four variables, substances use (ORm = 2.28, 95% CI = 1.01-5.16) and perceived lower level of RP's acceptance of condom use (ORm = 17.22; 95% CI = 5.06-58.62) were selected by the forward stepwise logistic regression model.Conclusions: MSM with RP in Hong Kong is subjected to high risk of HIV transmission. Risk factors of UAI are multi-dimensional and interventions need to take into account factors of structural, interpersonal and individual levels. © 2014 Cai and Lau; licensee BioMed Central Ltd. Source


Ramachandran A.,India Diabetes Research Foundation | Snehalatha C.,India Diabetes Research Foundation | Ma R.C.W.,Chinese University of Hong Kong
Diabetes Research and Clinical Practice | Year: 2014

According to the recent estimates by the International Diabetes Federation (IDF), South East-Asia (SEA) Region consisting of India, Sri Lanka, Bangladesh, Bhutan, Mauritius and Maldives, is home to more than 72 million adults with diabetes in 2013 and is expected to exceed 123 million in 2035. Nearly 95% of people with diabetes have type 2 diabetes (T2DM). Although type 1 diabetes (T1DM) is relatively rare in these countries, its prevalence is also rising. Furthermore, a large number (24.3 million) of people also have impaired glucose tolerance (IGT). Several characteristic differences are seen in the clinical and immunological presentation of these people when compared with their European counterparts.A sharp increase in the prevalence of T2DM has been observed in the SEA Region, both in urban and rural areas, which is mostly associated with the lifestyle transitions towards urbanisation and industrialisation. Evidence suggests that a large portion of T2DM may be preventable by lifestyle modification. However, morbidity and early mortality occur as a result of inadequate healthcare facilities for early detection and initiation of therapy, as well as suboptimal management of diabetes and associated morbidities. This is largely preventable by primary prevention of diabetes and enhancing awareness about the disease among the public and the healthcare providers. There is an urgent need for concerted efforts by government and non-governmental sectors to implement national programmes aimed at prevention, management and surveillance of the disease. © 2013 Elsevier Ireland Ltd. Source


Tottori S.,ETH Zurich | Zhang L.,Chinese University of Hong Kong | Peyer K.E.,ETH Zurich | Nelson B.J.,ETH Zurich
Nano Letters | Year: 2013

Controlling the motion of small objects in suspensions wirelessly is of fundamental interest and has potential applications in biomedicine for drug delivery and micromanipulation of small structures. Here we show that magnetic helical microstructures that propel themselves in the presence of rotating weak magnetic fields assemble into various configurations that exhibit locomotion and a change in swimming direction. The configuration is tuned dynamically, that is, assembly and disassembly occur, by the field input. We investigate a system that consists of two identical right-handed helices assembled at their center in order to model the motion of assembled swimmers. The swimming properties are dependent on both the component design and the assembly configuration. For particular designs and configurations, a reversal in swimming direction emerges, yet with other designs, a reversal in motion never appears. Understanding the locomotion of clustered chiral structures enables uni- and multidirectional navigation of this class of active suspensions. © 2013 American Chemical Society. Source


Fang Z.,Zhejiang Wanli University | Wang X.,Fudan University | Yuan X.,Chinese University of Hong Kong
IEEE Transactions on Signal Processing | Year: 2013

In this paper, we develop a unified framework for beamforming designs in non-regenerative multiuser two-way relaying (TWR). The core of our framework is the solution to the max-min signal-to-interference-plus-noise-ratio (SINR) problem for multiuser TWR. We solve this problem using a Dinkelbach-type algorithm with near-optimal performance and superlinear convergence. We show that, using the max-min SINR solution as a corner stone, the beamforming designs under various important criteria, such as weighted sum-rate maximization, weighted sum mean-square-error (MSE) minimization, and average bit-error-rate (BER) or symbol-error-rate (SER) minimization, etc, can be reformulated into a monotonic program. A polyblock outer approximation algorithm is then used to find the desired solutions with guaranteed convergence and optimal performance (provided that the core max-min SINR solver is optimal). Furthermore, the proposed unified approach can provide important insights for tackling the optimal beamforming designs in other emerging network models and settings. For instances, we extend the proposed framework to address the beamforming design in collaborative TWR and multi-pair MIMO TWR. Extensive numerical results are presented to demonstrate the merits of the proposed beamforming solutions. © 1991-2012 IEEE. Source


Ho F.Y.-Y.,University of Hong Kong | Chung K.-F.,University of Hong Kong | Yeung W.-F.,Chinese University of Hong Kong | Ng T.H.,University of Hong Kong | And 2 more authors.
Sleep Medicine Reviews | Year: 2015

Self-help cognitive-behavioral therapy (CBT) is an increasingly popular treatment option for insomnia. The objective of this meta-analysis was to compile an up-to-date evaluation on the efficacy, adherence, acceptability and dropout rate of self-help CBT for insomnia. We systematically searched six key electronic databases up until May 2013. Two researchers independently selected relevant publications, extracted data, and evaluated methodological quality according to the Cochrane criteria. Twenty randomized controlled trials were included; 10 of which were published after the last review up until January 2007. Meta-analysis of self-help CBT vs. waiting-list, routine care or no treatment was performed. Results showed that self-help CBT improved sleep, sleep-related cognitions and anxiety and depressive symptoms. Effect sizes for sleep-diary-derived sleep efficiency, sleep onset latency, and wake after sleep onset at immediate posttreatment were 0.80, 0.66, and 0.55, respectively. The average dropout rate of self-help CBT at immediate posttreatment was 14.5%, which was not significantly different from the 16.7% in therapist-administered CBT. Subgroup analyses supported the added benefit of telephone consultation. In conclusion, self-help CBT is efficacious and acceptable as an entry level of a stepped care model for insomnia. In places where face-to-face treatments are unavailable or too costly, self-help CBT can be considered as a compromise. © 2014 Elsevier Ltd. Source


BACKGROUND: The decision as to whether to use more expensive novel oral anticoagulants (NOACs) or invest resources for quality improvement of warfarin therapy requires input from both clinical and economic analyses. OBJECTIVE: Cost-effectiveness of NOACs compared to warfarin therapy at various levels of patient-time in therapeutic range (TTR) in patients with atrial fibrillation was examined, from the healthcare provider's perspective. DESIGN, SUBJECTS AND INTERVENTION: A Markov model was used to compare life-long economic and treatment outcomes of warfarin and NOACs in a hypothetical cohort of 65-year-old atrial fibrillation patients with CHADS2 scores of 2 or above. Model inputs were derived from clinical trials published in the literature. MAIN MEASURES: The outcome measure was incremental cost per quality-adjusted life-year (QALY) gained (ICER). KEY RESULTS: Using United States Dollar (USD) 50,000 as the threshold of willingness-to-pay per QALY, NOACs therapy was cost-effective when TTR of warfarin therapy was 60 % or below, or monthly cost of warfarin management increased by two-fold or more to achieve 70 % TTR. Warfarin therapy was cost-effective when TTR of warfarin was 70 % with up to a 1.5-fold increment in monthly cost of care, or when TTR reached 75 % with monthly cost of warfarin care increased up to three-fold. At TTR 60 %, 70 % and 75 %, NOACs was cost-effective when monthly drug cost was < USD 200, < USD 122-185 and < USD 85-145, respectively. 10,000 Monte Carlo simulations showed NOACs to be cost-effective 83.6 %, 50.7 % and 32.7 % of the time at TTR of 60 %, 70 % and 75 %, respectively. CONCLUSIONS: The acceptance of NOACs as cost-effective was highly dependent upon drug cost, anticoagulation control for warfarin, and anticoagulation service cost. © 2013 Society of General Internal Medicine. Source


Wei C.,Nankai University | Li Y.,Nankai University | Cai X.,Chinese University of Hong Kong
International Journal of Production Economics | Year: 2011

We consider an inventory and production planning problem with uncertain demand and returns, in which the product return process is integrated into the manufacturing process over a finite planning horizon. We first propose an inventory control model for the return and remanufacturing processes with consideration of the uncertainty of the demand and returns. Then a robust optimization approach is applied to deal with the uncertainty of the problem through formulating a robust linear programming model. Moreover, properties on the robust optimization model are studied, and an equivalent robust optimization model based on duality theory is obtained which allows the solutions to be derived more efficiently. Finally, we provide a set of numerical examples to verify the effectiveness of the approach and analyze the effects of the key parameters on the solutions. © 2009 Elsevier B.V. All rights reserved. Source


Yang W.,Chinese University of Hong Kong
Oncogene | Year: 2015

Accumulating evidence reveals the effectiveness of epigenetic therapy in gastric cancer. However, the molecular mechanisms and targets underlying such therapeutic responses remain elusive. Herein, we report an aberrant yet therapeutically rectifiable epigenetic signaling in gastric carcinogenesis. Administration of DNA-demethylating drug 5-aza-2′-deoxycytidine (5-aza-dC) reduced gastric cancer incidence by ~74% (P<0.05) in N-nitroso-N-methylurea-treated mice. Through genome-wide methylation scanning, novel promoter hypermethylation-silenced and drug-targeted genes were identified in the resected murine stomach tumors and tissues. We uncovered that growth/differentiation factor 1 (Gdf1), a member of the transforming growth factor-β superfamily, was silenced by promoter hypermethylation in control tumor-bearing mice, but became reactivated in 5-aza-dC-treated mice (P<0.05). In parallel, the downregulated SMAD2/3 phosphorylation in gastric cancer was revived by 5-aza-dC in vivo. Such hypermethylation-dependent silencing and 5-aza-dC-mediated reactivation of GDF1-SMAD2/3 activity was conserved in human gastric cancer cells (P<0.05). Subsequent functional characterization further revealed the antiproliferative activity of GDF1, which was exerted through activation of SMAD2/3/4-mediated signaling, transcriptional controls on p15, p21 and c-Myc cell-cycle regulators and phosphorylation of retinoblastoma protein. Clinically, hypermethylation and loss of GDF1 was significantly associated with reduced phosphorylated-SMAD2/3 and poor survival in stomach cancer patients (P<0.05). Taken together, we demonstrated a causal relationship between DNA methylation and a tumor-suppressive pathway in gastric cancer. Epigenetic silencing of GDF1 abrogates the growth-inhibitory SMAD signaling and renders proliferation advantage to gastric epithelial cells during carcinogenesis. This study lends support to epigenetic therapy for gastric cancer chemoprevention and identifies a potential biomarker for prognosis.Oncogene advance online publication, 27 July 2015; doi:10.1038/onc.2015.276. © 2015 Macmillan Publishers Limited Source


Zeng H.,Chinese University of Hong Kong | Cui X.,University of Hong Kong
Chemical Society Reviews | Year: 2015

The ultimate goal of making atomically thin electronic devices stimulates intensive research on layered materials, in particular the group-VI transition metal dichalcogenides (TMDs). Atomically thin group-VI TMD crystals with a 2H stacking order emerging as a family of intrinsic 2-dimensional (2D) semiconductors with a sizeable bandgap in the visible and near infrared range satisfy numerous requirements for ultimate electronics and optoelectronics. In addition, the characteristic inversion symmetry breaking presented in monolayer TMDs leads to non-zero but contrasting Berry curvatures and orbit magnetic moments at K/K′ valleys located at the corners of the first Brillouin zone. These features provide an opportunity to manipulate electrons' additional internal degrees of freedom, namely the valley degree of freedom, making monolayer TMDs a promising candidate for the conceptual valleytronics. Besides, the strong spin-orbit interactions and the subsequent spin-valley coupling demonstrated in atomically thin group-VI TMDs open up potential routes towards quantum manipulation. In this tutorial review, we highlight recent advances in the optical study on electronic structures, vibrational properties, excitonic effects, valley dependent optical selection rules, and the interplay of valley, spin, and layer degrees of freedoms in this class of atomic 2D semiconductors including MoS2, MoSe2, WS2, and WSe2. © 2015 The Royal Society of Chemistry. Source


Ma W.-K.,Chinese University of Hong Kong | Hsieh T.-H.,Realtek Semiconductor Corporation | Chi C.-Y.,National Tsing Hua University
IEEE Transactions on Signal Processing | Year: 2010

In real-world applications such as those for speech and audio, there are signals that are nonstationary but can be modeled as being stationary within local time frames. Such signals are generally called quasi-stationary or locally stationary signals. This paper considers the problem of direction-of-arrival (DOA) estimation of quasi-stationary signals. Specifically, in our problem formulation we assume: i) sensor array of uniform linear structure; ii) mutually uncorrelated wide-sense quasi-stationary source signals; and iii) wide-sense stationary noise process with unknown, possibly nonwhite, spatial covariance. Under the assumptions above and by judiciously examining the structures of local second-order statistics (SOSs), we develop a KhatriRao (KR) subspace approach that has two notable advantages. First, through an identifiability analysis, it is proven that this KR subspace approach can operate even when the number of sensors is about half of the number of sources. The idea behind is to make use of a virtual array structure provided inherently in the local SOS model, of which the degree of freedom is about twice of that of the physical array. Second, the KR formulation naturally provides a simple yet effective way of eliminating the unknown spatial noise covariance from the signal SOSs. Extensive simulation results are provided to demonstrate the effectiveness of the KR subspace approach under various situations. © 2006 IEEE. Source


Chan F.K.L.,Chinese University of Hong Kong | Lanas A.,University of Zaragoza | Scheiman J.,University of Michigan | Berger M.F.,Pfizer | And 2 more authors.
The Lancet | Year: 2010

Background Cyclo-oxygenase (COX)-2-selective non-steroidal anti-inflammatory drugs (NSAIDs) and non-selective NSAIDs plus a proton-pump inhibitor (PPI) have similar upper gastrointestinal outcomes, but risk of clinical outcomes across the entire gastrointestinal tract might be lower with selective drugs than with non-selective drugs. We aimed to compare risk of gastrointestinal events associated with celecoxib versus diclofenac slow release plus omeprazole. aMethods We undertook a 6-month, double-blind, randomised trial in patients with osteoarthritis or rheumatoid arthritis at increased gastrointestinal risk at 196 centres in 32 countries or territories. Patients tested negative for Helicobacter pylori and were aged 60 years and older or 18 years and older with previous gastroduodenal ulceration. We used a computer-generated randomisation schedule to assign patients in a 1:1 ratio to receive celecoxib 200 mg twice a day or diclofenac slow release 75 mg twice a day plus omeprazole 20 mg once a day. Patients and investigators were masked to treatment allocation. The primary endpoint was a composite of clinically significant upper or lower gastrointestinal events adjudicated by an independent committee. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00141102. Findings 4484 patients were randomly allocated to treatment (2238 celecoxib; 2246 diclofenac plus omeprazole) and were included in intention-to-treat analyses. 20 (0·9%) patients receiving celecoxib and 81 (3·8%) receiving diclofenac plus omeprazole met criteria for the primary endpoint (hazard ratio 4·3, 95% CI 2·6-7·0; p<0·0001). 114 (6%) patients taking celecoxib versus 167 (8%) taking diclofenac plus omeprazole withdrew early because of gastrointestinal adverse events (p=0·0006). Interpretation Risk of clinical outcomes throughout the gastrointestinal tract was lower in patients treated with a COX-2-selective NSAID than in those receiving a non-selective NSAID plus a PPI. These findings should encourage review of approaches to reduce risk of NSAID treatment. Funding Pfizer Inc. Source


Law C.K.,Chinese University of Hong Kong
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We present an interaction scheme that exhibits a dynamical effect of virtual photons carried by a vacuum-field dressed two-level atom in the ultrastrong-coupling regime. We show that, with the aid of an external driving field, virtual photons provide a transition matrix element that enables the atom to evolve coherently and reversibly to an auxiliary level accompanied by the emission of a real photon. The process corresponds to a type of vacuum Rabi oscillation, and we show that the effective vacuum Rabi frequency is proportional to the amplitude of a single virtual photon in the ground state. Therefore, the interaction scheme could serve as a probe of ground-state structures in the ultrastrong-coupling regime. © 2013 American Physical Society. Source


Ramsden M.,Chinese University of Hong Kong
Journal of Conflict and Security Law | Year: 2011

Anwar Al-Awlaki, the high-profile proponent of violent jihad, is reported to have taken on a leadership role in Al-Qaeda in the Arabian Peninsula (AQAP), a US-designated terrorist organization that has committed a chain of terrorist attacks against predominantly US and Yemen targets. After evidence of Al-Awlaki's involvement in personally instructing acts of terrorism, he was reportedly targeted by US drones just days after the death of Osama bin Laden. Al-Awlaki is said to be harboured by tribes in a remote terrorist safe haven in the Shabwa province of Yemen. Given that Al-Awlaki is present in an area outside of active armed conflict, the USA must justify any killing according to International Human Rights Law (IHRL). It must show that any targeted killing has a domestic legal basis, would be proportionate to the legitimate aim of saving life and absolutely necessary, after less harmful means were exhausted. But a strict domestic law enforcement standard should not necessarily be applied in all cases. Rather in addressing threats from terrorist safe havens abroad, the feasibility of arrest and the concept of imminence must be adapted. Given Al-Awlaki's leadership position in AQAP, an organization openly committed to, and involved in, ongoing acts of terrorism, an arguable case can be made that his targeted killing would be justified under IHRL. © Oxford University Press 2011; all rights reserved. Source


Sillence E.,Northumbria University | Mo P.K.H.,Chinese University of Hong Kong
Health Expectations | Year: 2014

Background Experiential websites such as message forums and blogs allow Prostate Cancer (PCa) patients to communicate their health decisions to peers. The issues surrounding this form of indirect involvement in public health are little understood. Objective This paper explores the types of decision-making processes that people are exposed to on PCa online message boards. The kinds of treatment choices patients are making and the reports of their decision-making processes to peers through an online environment are examined in the context of the Heuristic Systematic Model. Method Messages about treatment decision making were collected from four PCa websites. In total, 137 messages were selected from blogs and online forums and their decision-making processes coded. Results Men looking online for information about treatment options for PCa are exposed to a range of decision-making processes. Just under half (49.6%) of the messages reported non-systematic decision processes, with deferral to the doctor and proof of cancer removal being the most common. For systematic processing (36.5%), messages most commonly considered treatment outcomes and side-effects. Processes did not vary between the blogs and online forums. Discussion and conclusion Compared to previous studies far fewer messages reported non-systematic decision processes and only a small number of messages reflected lay beliefs or misbeliefs about PCa treatment. Implications for men and their clinicians of seeking health information online are discussed. © 2012 John Wiley & Sons Ltd. Source


Lan H.Y.,Chinese University of Hong Kong
International Journal of Biological Sciences | Year: 2011

TGF-β1 has been long considered as a key mediator in renal fibrosis and induces renal scarring largely by activating its downstream Smad signaling pathway. Interestingly, while mice overexpressing active TGF-β1 develop progressive renal injury, latent TGF-β1 plays a protective role in renal fibrosis and inflammation. Under disease conditions, Smad2 and Smad3 are highly activated, while Smad7 is degraded through the ubiquitin proteasome degradation mechanism. In addition to TGF-β1, many pathogenic mediators such as angiotensin II and advanced glycation end products can also activate the Smad pathway via both TGF-β-dependent and independent mechanisms. Smads interact with other signaling pathways, such as the MAPK and NF-κB pathways, to positively or negatively regulate renal inflammation and fibrosis. Studies from gene knockout mice demonstrate that TGF-β1 acts by stimulating its downstream Smads to diversely regulate kidney injury. In the context of renal fibrosis and inflammation, Smad3 is pathogenic, while Smad2 and Smad7 are protective. Smad4 exerts its diverse roles by transcriptionally enhancing Smad3-mediated renal fibrosis while inhibiting NF-κB-driven renal inflammation via a Smad7-dependent mechanism. Furthermore, we also demonstrated that TGF-β1 acts by stimulating Smad3 to positively or negatively regulate microRNAs to exert its fibrotic role in kidney disease. In conclusion, TGF-β/Smad signaling is a major pathway leading to kidney disease. Smad3 is a key mediator in renal fibrosis and inflammation, whereas Smad2 and Smad7 are renoprotective. Smad4 exerts its diverse role in promoting renal fibrosis while inhibiting inflammation. Thus, targeting the downstream TGF-β/Smad3 signaling pathway by gene transfer of either Smad7 or Smad3-dependent microRNAs may represent a specific and effective therapeutic strategy for kidney disease. © Ivyspring International Publisher. Source


Ng M.K.,Chinese University of Hong Kong
Environment and Planning C: Government and Policy | Year: 2011

Flyvbjerg argues that power often overrides rationality as power wielders frequently portray 'rationalisation' as rationality to define 'truths' that justify their actions. When power is great, rationality diminishes. In confrontation, rationality yields to power. In this paper I contest these arguments. Through differentiating the concept of power into 'outcome power' held by those with privileged access to authority and 'social power', the power of resistance vested in everyone, and by distinguishing the concept of rationality into 'technical', 'strategic' (rationalisation), and 'value' ration- alities, I assert that, in confrontations, individuals with social power can counteract outcome power and develop their value rationality to reproblematise issues for transformative changes. A study of the reclamation debates in Hong Kong illustrates how social power has augmented value rationality, challenging the government's outcome power and its rationalisation for further harbour reclamation, reproblematising the harbour as a unique natural heritage feature worthy of protection by law. © 2011 Pion Ltd and its Licensors. Source


Vitellogenin (VTG) and apolipoprotein (APO) play a central role in animal reproduction and lipid circulation, respectively. Although previous studies have examined the structural and functional relationships of these large lipid transfer proteins (LLTPs) from an evolutionary perspective, the mechanism in generating these different families have not been addressed in invertebrates. In this study, the most comprehensive phylogenetic and genomic analysis of the LLTP superfamily genes is carried out. We propose the expansion and diversification of LLTPs in invertebrates are mediated via retrotransposon-mediated duplications, followed by either subfunctionalization or neofunctionalization in different lineages. In agreement with a previous hypothesis, our analysis suggests that all LLTPs originate from a series of duplications of a primitive yolk protein gene similar to VTG. Two early consecutive duplications of the yolk protein genes resulted in the formation of microsomal triglyceride transfer protein (MTP) and the APO gene ancestor. Gains and losses of domains and genes occurred in each of these families in different animal lineages, with MTP becoming truncated. MTP maintained only the components stabilizing the huge lipoprotein particle. Surprisingly, for the first time, two VTG-like protein families were found to independently arise in the lineages of insects. This work consolidates the reconstruction of the evolutionary roadmap of the LLTP superfamily and provides the first mechanistic explanation on the expansion of family members via retrotransposition in invertebrates. Source


Chiu P.W.Y.,Chinese University of Hong Kong
Clinical Gastroenterology and Hepatology | Year: 2014

Gastrointestinal cancers are among the commonest cancers worldwide. Treatment of these cancers at an early stage will result in a significantly better prognosis. Endoscopic submucosal dissection (ESD) is a new method of endoscopic resection that can achieve higher rates of en bloc resection for early gastrointestinal neoplasia. Three retrospective case-control studies showed that ESD achieved significantly higher en bloc resection with lower recurrence rates than endoscopic mucosal resection for treatment of early gastric cancers. Most of the reports on clinical outcomes of ESD were from countries with a high incidence of gastric cancers, including Japan and Korea. The development of ESD has been slow for countries outside Japan and Korea because ESD requires a high level of endoscopic skills, and the dissection was performed single-handedly without assistance. A newly developed robotic endoscopic platform will enhance the performance of ESD through the use of 2 robotic arms: one arm for retraction of the mucosa and the other arm for dissection. © 2014 AGA Institute. Source


Chan F.K.L.,Chinese University of Hong Kong
Journal of Gastroenterology and Hepatology (Australia) | Year: 2012

Low-dose aspirin (ASA) has emerged as one of the most important causes of peptic ulcer bleeding in developed countries. Among the risk factors of ASA-associated ulcer bleeding, Helicobacter pylori infection is one of the few that is treatable. Recent evidence showed that among patients with a history of ASA-associated ulcer bleeding, the long-term incidence of recurrent bleeding with ASA use is low after eradication of H. pylori alone. Thus, test-and-treat H. pylori is a potentially useful strategy for ASA users with high ulcer risk. However, the risk of bleeding is further increased by combining other anti-platelet drugs (e.g. clopidogrel) with ASA in acute coronary syndromes and coronary stent placement. There is good evidence that co-therapy with a proton-pump inhibitor (PPI) reduces upper gastrointestinal bleeding with ASA alone or dual anti-platelet therapy. Recently, several meta-analyses of observational studies found that concurrent use of PPI and clopidogrel was associated with increased risk of major adverse cardiovascular events. Overall, the evidence does not suggest a clinically important interaction between PPIs and clopidogrel. However, there is a subset of patients who have reduced conversion of clopidogrel to its active metabolites due to genetic polymorphism of hepatic P-450 (carriers of CYP2C19 loss-of-function alleles). Since PPIs are also metabolized by similar hepatic enzymes, it is uncertain whether patients carrying CY2C19 loss-of-function alleles are susceptible to concomitant PPI use. In the future, management of patients on dual anti-platelet therapy needs to be individualized according to their thrombotic and bleeding risks. © 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd. Source


Xia Q.,Huazhong University of Science and Technology | Wang M.Y.,Chinese University of Hong Kong | Shi T.,Huazhong University of Science and Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2015

The topology optimization problem with pressure load is solved by using a level set method. The free boundary and the pressure boundary of a structure are represented separately as two zero-level sets of two level set functions, and they are independently propagated during the optimization by solving two Hamilton-Jacobi equations. In order to prevent the two boundaries from touching or crossing each other, the design velocities of the two boundaries that amount to the steepest descent directions are modified. The optimization problem of minimum compliance with perimeter regularization is considered. The shape derivatives of the two boundaries are derived by using the material derivative approach and the adjoint method. The finite element analysis is done through an Eulerian method by employing a fixed mesh and an artificial weak material that represents void. Numerical examples in two dimensions are investigated. © 2014 Elsevier B.V. Source


Meng X.-M.,Anhui Medical University | Nikolic-Paterson D.J.,Monash University | Lan H.Y.,Chinese University of Hong Kong
Nature Reviews Nephrology | Year: 2014

Many types of kidney injury induce inflammation as a protective response. However, unresolved inflammation promotes progressive renal fibrosis, which can culminate in end-stage renal disease. Kidney inflammation involves cells of the immune system as well as activation of intrinsic renal cells, with the consequent production and release of profibrotic cytokines and growth factors that drive the fibrotic process. In glomerular diseases, the development of glomerular inflammation precedes interstitial fibrosis; although the mechanisms linking these events are poorly understood, an important role for tubular epithelial cells in mediating this link is gaining support. Data have implicated macrophages in promoting both glomerular and interstitial fibrosis, whereas limited evidence suggests that CD4 + T cells and mast cells are involved in interstitial fibrosis. However, macrophages can also promote renal repair when the cause of renal injury can be resolved, highlighting their plasticity. Understanding the mechanisms by which inflammation drives renal fibrosis is necessary to facilitate the development of therapeutics to halt the progression of chronic kidney disease. © 2014 Macmillan Publishers Limited. Source


Hon K.L.,Chinese University of Hong Kong
World Journal of Pediatrics | Year: 2011

Background: Filicide is the tragic crime of murdering one's own child. This report aims to summarize all such cases involving fi licide with suicide and analyze possible risk factors pertinent to the city of Hong Kong. Methods: All cases involving filicide with suicide between 1998 and 2010 were reviewed and possible risk factors pertinent to the city of Hong Kong were analyzed. Results: During the study period, there were 14 cases of parents committing suicide and filicide in Hong Kong. Sixteen victims (9 boys and 7 girls, ages range from 2 months to 33 years) and a three-month fetus were involved; only two survived. The parents (12 mothers and 3 fathers, ages range from 25 years to 64 years) all died. The majority of perpetrators (n=7) had alleged history of psychiatric illness or post-puerperal depression. The majority jumped from heights (n=11 off tall buildings, n=1 off a bridge), one father used town-gas, and one couple burned charcoal (carbon monoxide poisoning). Conclusions: These rare but tragic cases involved children of both sexes and all ages. Although psychosocial risk factors may be clues for interventions, the rarity of these incidents and the impulsiveness of the act make preventive measures virtually impossible in a city full of high-rise buildings. © Children's Hospital, Zhejiang University School of Medicine, China and Springer-Verlag Berlin Heidelberg 2011. All rights reserved. Source


Zhang Y.,Johns Hopkins University | Yew W-W.,Chinese University of Hong Kong
International Journal of Tuberculosis and Lung Disease | Year: 2015

Drug-resistant tuberculosis (DR-TB), including multiand extensively drug-resistant TB, is posing a significant challenge to effective treatment and TB control worldwide. New progress has been made in our understanding of the mechanisms of resistance to anti-tuberculosis drugs. This review provides an update on the major advances in drug resistance mechanisms since the previous publication in 2009, as well as added information on mechanisms of resistance to new drugs and repurposed agents. The recent application of whole genome sequencing technologies has provided new insight into the mechanisms and complexity of drug resistance. However, further research is needed to address the significance of newly discovered gene mutations in causing drug resistance. Improved knowledge of drug resistance mechanisms will help understand the mechanisms of action of the drugs, devise better molecular diagnostic tests for more effective DR-TB management (and for personalised treatment), and facilitate the development of new drugs to improve the treatment of this disease. © 2015 The Union. Source


Luo H.,Chinese University of Hong Kong | Moran M.A.,University of Georgia
Trends in Microbiology | Year: 2015

Heterotrophic bacteria in pelagic marine environments are frequently categorized into two canonical ecological groups: patch-associated and free-living. This framework provides a conceptual basis for understanding bacterial utilization of oceanic organic matter. Some patch-associated bacteria are ecologically linked with eukaryotic phytoplankton, and this observation fits with predicted coincidence of their genome expansion with marine phytoplankton diversification. By contrast, free-living bacteria in today's oceans typically live singly with streamlined metabolic and regulatory functions that allow them to grow in nutrient-poor seawater. Recent analyses of marine Alphaproteobacteria suggest that some free-living bacterioplankton lineages evolved from patch-associated ancestors up to several hundred million years ago. While evolutionary analyses agree with the hypothesis that natural selection has maintained these distinct ecological strategies and genomic traits in present-day populations, they do not rule out a major role for genetic drift in driving ancient ecological switches. These two evolutionary forces may have acted on ocean bacteria at different geological time scales and under different geochemical constraints, with possible implications for future adaptations to a changing ocean. New evolutionary models and genomic data are leading to a more comprehensive understanding of marine bacterioplankton evolutionary history. © 2015 Elsevier Ltd. Source


Sanderson J.E.,Chinese University of Hong Kong
JACC: Heart Failure | Year: 2014

It is well recognized that many patients presenting with heart failure have a normal left ventricular ejection fraction. There has been debate about the correct name for this condition including originally Diastolic Heart Failure (DHF), Heart Failure with a Normal Ejection Fraction (HFNEF), and more recently Heart Failure with a Preserved Ejection Fraction, usually abbreviated to HFpEF. In this viewpoint is it argued that 'Preserved' is the least appropriate word to use, as ejection fraction declines over time and furthermore it is never explained why the 'p' is small. The most honest acronym is HFNEF. © 2014 American College of Cardiology Foundation. Source


BACKGROUND: Increase in expression of substance P (SP) and calcitonin gene-related peptide (CGRP) has been reported in clinical samples of tendinopathy. PURPOSE: To examine the spatial-temporal expression of these neuropeptides as well as their association with activity-related tendon pain, matrix degeneration, failed healing, and pathologic calcification in an established collagenase-induced tendon injury rat model. STUDY DESIGN: Controlled laboratory study. METHODS: Collagenase or saline was injected into the patellar tendon of rats. At weeks 2, 4, 8, 12, and 16, just before the rats were sacrificed, the double-stance duration of rats was examined by gait analysis method. After sacrifice, the patellar tendons were harvested for histologic analysis and immunohistochemical staining of SP and CGRP. RESULTS: There was an increase of SP and CGRP immunopositivity in tendon fibroblasts at week 2. The immunopositive signals decreased at weeks 4 and 8 and were observed in chondrocyte-like cells. At weeks 12 and 16, the immunopositive staining increased again and was observed in cells embedded in calcific deposits in addition to tendon fibroblasts and chondrocyte-like cells. The expression pattern was consistent with matrix degeneration, calcification, and failed healing in the animal model. There were significant positive correlations of immunopositivity of SP (rho = .502, P = .002) and CGRP (rho = .483, P = .003) with double-stance duration after collagenase injection. CONCLUSION: There was increased expression of SP and CGRP after collagenase-induced tendon injury, and their expression was positively associated with double-stance duration. Clinical Relevance Substance P and CGRP might be involved in the pathogenesis and origin of pain of tendinopathy and could be the targets for future intervention. Source


Gin T.,Chinese University of Hong Kong
Current Opinion in Anaesthesiology | Year: 2013

PURPOSE OF REVIEW: Many studies of new intravenous sedative drugs have been published last year, including several phase I trials. This review provides a brief summary of these studies, with recommendations for selected reading. RECENT FINDINGS: Remimazolam is a rapidly metabolized benzodiazepine. Early clinical trials confirm more rapid recovery compared with midazolam. Etomidate analogues can be designed with rapid metabolism and without adrenocortical suppression, but research is only at the preclinical stage. MR04A3 and AZD3043 are gamma-aminobutyric acid A agonists with phase I data, but the outlook for further development is uncertain. Pioneers of intravenous emulsions of volatile anesthetics continue their work. SUMMARY: Many of the new sedative drugs were designed to undergo rapid metabolism. Remimazolam has great potential to enter clinical practice because of its rapid offset of action. © 2013 Lippincott Williams & Wilkins. Source


Chu T.T.,Chinese University of Hong Kong
The British journal of nutrition | Year: 2012

Previous studies have suggested that Lingzhi (Ganoderma lucidum) has antioxidant effects and possibly beneficial effects on blood pressure, plasma lipids and glucose, but these have not been confirmed in subjects with mild hypertension or hyperlipidaemia. The objective of the present study was to assess the cardiovascular, metabolic, antioxidant and immunomodulatory responses to therapy with Lingzhi in patients with borderline elevations of blood pressure and/or cholesterol in a controlled cross-over trial. A total of twenty-six patients received 1·44 g Lingzhi daily or matching placebo for 12 weeks in a randomised, double-blind, cross-over study with placebo-controlled run-in and cross-over periods. Body weight, blood pressure, metabolic parameters, urine catecholamines and cortisol, antioxidant status and lymphocyte subsets were measured after each period. Lingzhi was well tolerated and data from twenty-three evaluable subjects showed no changes in BMI or blood pressure when treated with Lingzhi or placebo. Plasma insulin and homeostasis model assessment-insulin resistance were lower after treatment with Lingzhi than after placebo. TAG decreased and HDL-cholesterol increased with Lingzhi but not with placebo in the first treatment period, but significant carry-over effects prevented complete analysis of these parameters. Urine catecholamines and cortisol, plasma antioxidant status and blood lymphocyte subsets showed no significant differences across treatments. Results indicate that Lingzhi might have mild antidiabetic effects and potentially improve the dyslipidaemia of diabetes, as shown previously in some animal studies. Further studies are desirable in patients with hyperglycaemia. Source


Shi L.,Hefei University of Technology | Li Q.,Chinese University of Hong Kong
CrystEngComm | Year: 2011

Quaternary Cu2ZnSnSe4 single crystalline nanosheets have been synthesized in a controlled manner with a convenient solvothermal approach by simply modifying the reaction conditions. The presence of ethylenediamine (En) plays a key role in the preparation of Cu 2ZnSnSe4 nanosheets while the thickness of the as-prepared Cu2ZnSnSe4 nanosheets is strongly dependent on the amount of En. The formation mechanism of Cu2ZnSnSe4 nanosheets was discussed. The products were characterized using X-ray powder diffraction, Raman, energy dispersive X-ray spectrometry, transmission electron microscopy, scanning electron microscopy and UV-Vis spectrophotometry. © 2011 The Royal Society of Chemistry. Source


Wu J.C.Y.,Chinese University of Hong Kong
Gastroenterology and Hepatology | Year: 2010

Due to unsatisfactory results from conventional treatment of irritable bowel syndrome (IBS), complementary and alternative medicine (CAM) modalities are increasingly popular treatment alternatives. Unfortunately, most CAM clinical trials have been of poor quality, and the efficacies of these therapies have not been adequately elucidated, even through systematic reviews or meta-analyses. There is also a general lack of understanding of their mechanisms of action. Currently, insufficient evidence exists to support the use of traditional Chinese medicine, acupuncture, meditation, and reflexology for treatment of IBS. However, there is some evidence supporting the use of peppermint oil and gut-directed hypnotherapy for IBS treatment. Due to mounting evidence of the microbiologic and immunologic basis of IBS, probiotics and exclusion diets are also becoming promising treatment modalities. This paper will review the current literature on various CAM practices for IBS treatment and appraise their advantages and disadvantages in clinical practice. Source


Jin J.,Wuhan University of Technology | Yu J.,Wuhan University of Technology | Liu G.,CAS National Center for Nanoscience and Technology | Wong P.K.,Chinese University of Hong Kong
Journal of Materials Chemistry A | Year: 2013

Single crystalline hexagonal CdS nanowires were prepared by a solvothermal method using ethylenediamine as a solvent. Pt/CdS nanocomposites were produced by different reduction methods and characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, UV-visible spectroscopy, nitrogen absorption, pulse H2 chemisorption and X-ray photoelectron spectroscopy. The photocatalytic performance of the as-synthesized Pt/CdS nanocomposites was evaluated towards H2 generation from a lactic acid aqueous solution under visible light (λ ≥ 420 nm). The sample prepared by the NaBH4 reduction method showed a higher photocatalytic H2-production activity than the sample prepared by the photo-reduction deposition method. A remarkable H 2-production rate of 1.49 mmol h-1 with a quantum efficiency (QE) of 61.7% was first achieved on the former with a small amount of Pt (0.3 wt%) as a co-catalyst. The photocatalytic activity difference of the samples is because reduction methods influence the size and dispersion of Pt nanoparticles (NPs), which further influence the photocatalytic H 2-production activity. The sample from the NaBH4 reduction method contains smaller Pt NPs (ca. 1-2 nm) and has higher Pt dispersion (72%), thus resulting in the higher H2-production activity. Further experiments showed that the one-dimensional nanostructure markedly enhanced the photocatalytic H2-production activity of CdS. After ball milling of the nanowires, which leads to destruction of their structure, the photocatalytic H2-production activity of CdS decreases by more than 30%. The underlying mechanism for the observed photocatalytic H2-production performance of Pt/CdS nanocomposites was discussed. © 2013 The Royal Society of Chemistry. Source


Liang Y.,Macau University of Science and Technology | Leung K.-S.,Chinese University of Hong Kong
Applied Soft Computing Journal | Year: 2011

This paper introduces a new technique called adaptive elitist-population search method. This technique allows unimodal function optimization methods to be extended to efficiently explore multiple optima of multimodal problems. It is based on the concept of adaptively adjusting the population size according to the individuals' dissimilarity and a novel direction dependent elitist genetic operators. Incorporation of the new multimodal technique in any known evolutionary algorithm leads to a multimodal version of the algorithm. As a case study, we have integrated the new technique into Genetic Algorithms (GAs), yielding an Adaptive Elitist-population based Genetic Algorithm (AEGA). AEGA has been shown to be very efficient and effective in finding multiple solutions of complicated benchmark and real-world multimodal optimization problems. We demonstrate this by applying it to a set of test problems, including rough and stepwise multimodal functions. Empirical results are also compared with other multimodal evolutionary algorithms from the literature, showing that AEGA generally outperforms existing approaches. © 2010 Elsevier B.V. All rights reserved. Source


Wong G.L.-H.,Chinese University of Hong Kong
World Journal of Hepatology | Year: 2013

Assessment of liver fibrosis and steatosis is crucial in chronic liver diseases in order to determine the prognosis, the need of treatment, as well as monitor disease progression and response to treatment. Liver biopsy is limited by its invasiveness and patient acceptability. Transient elastography (TE, Fibroscan®) is a non-invasive tool with satisfactory accuracy and reproducibility to estimate liver fibrosis and steatosis. TE has been well validated in major liver diseases including chronic hepatitis B and C, non-alcoholic fatty liver disease, alcoholic liver disease, primary biliary cirrhosis, and primary sclerosing cholangitis. As alanine aminotransferase (ALT) is one of the major confounding factors of liver stiffness in chronic hepatitis B, an ALT-based algorithm has been developed and higher liver stiffness measurements (LSM) cutoff values for different stages of liver fibrosis should be used in patients with elevated ALT levels up to 5 times of the upper limit of normal. Otherwise falsely-high LSM results up to cirrhotic range may occur during ALT flare. TE is also useful in predicting patient prognosis such as development of hepatocellular carcinoma (HCC), portal hypertension, post-operative complications in HCC patients, and also survival. Unfortunately, failed acquisition of TE is common in obese patients. Furthermore, obese patients may have higher LSM results even in the same stage of liver fibrosis. The new XL probe, a larger probe with lower ultrasound frequency and deeper penetration, increases the success rate of TE in obese patients. The median LSM value with XL probe was found to be lower than that by the conventional M probe, hence cutoff values approximately 1.2 to 1.3 kPa lower than those of M probe should be adopted. Recent studies revealed a novel ultrasonic controlled attenuation parameter (CAP) of the machine is a useful parameter to detect even low-grade steatosis noninvasively. CAP may also be used to quantify liver steatosis by applying different cutoff values. As both LSM and CAP results are instantly available at same measurement, this makes TE a very convenient tool to assess any patients who are suspected or confirmed to suffer from chronic liver diseases. © 2013 Baishideng. Source


Xu L.,Chinese University of Hong Kong
Frontiers of Electrical and Electronic Engineering in China | Year: 2010

Firstly proposed in 1995 and systematically developed in the past decade, Bayesian Ying-Yang learning1) is a statistical approach for a two pathway featured intelligent system via two complementary Bayesian representations of a joint distribution on the external observation X and its inner representation R, which can be understood from a perspective of the ancient Ying-Yang philosophy. We have q(X, R) = q(X{pipe}R)q(R) as Ying that is primary, with its structure designed according to tasks of the system, and p(X, R) = p(R{pipe}X)p(X) as Yang that is secondary, with p(X) given by samples of X while the structure of p(R{pipe}X) designed from Ying according to a Ying-Yang variety preservation principle, i.e., p(R{pipe}X) is designed as a functional with q(X{pipe}R), q(R) as its arguments. We call this pair Bayesian Ying-Yang (BYY) system. A Ying-Yang best harmony principle is proposed for learning all the unknowns in the system, in help of an implementation featured by a five action circling under the name of A5 paradigm. Interestingly, it coincides with the famous ancient WuXing theory that provides a general guide to keep the A5 circling well balanced towards a Ying-Yang best harmony. This BYY learning provides not only a general framework that accommodates typical learning approaches from a unified perspective but also a new road that leads to improved model selection criteria, Ying-Yang alternative learning with automatic model selection, as well as coordinated implementation of Ying based model selection and Yang based learning regularization. This paper aims at an introduction of BYY learning in a twofold purpose. On one hand, we introduce fundamentals of BYY learning, including system design principles of least redundancy versus variety preservation, global learning principles of Ying-Yang harmony versus Ying-Yang matching, and local updating mechanisms of rival penalized competitive learning (RPCL) versus maximum a posteriori (MAP) competitive learning, as well as learning regularization by data smoothing and induced bias cancelation (IBC) priori. Also, we introduce basic implementing techniques, including apex approximation, primal gradient flow, Ying-Yang alternation, and Sheng-Ke-Cheng-Hui law. On the other hand, we provide a tutorial on learning algorithms for a number of typical learning tasks, including Gaussian mixture, factor analysis (FA) with independent Gaussian, binary, and non-Gaussian factors, local FA, temporal FA (TFA), hidden Markov model (HMM), hierarchical BYY, three layer networks, mixture of experts, radial basis functions (RBFs), subspace based functions (SBFs). This tutorial aims at introducing BYY learning algorithms in a comparison with typical algorithms, particularly with a benchmark of the expectation maximization (EM) algorithm for the maximum likelihood. These algorithms are summarized in a unified Ying-Yang alternation procedure with major parts in a same expression while differences simply characterized by few options in some subroutines. Additionally, a new insight is provided on the ancient Chinese philosophy of Yin-Yang and WuXing from a perspective of information science and intelligent system. © 2010 Higher Education Press and Springer-Verlag Berlin Heidelberg. Source


Ho S.-W.,University of South Australia | Yeung R.W.,Chinese University of Hong Kong
IEEE Transactions on Information Theory | Year: 2010

Strong typicality, which is more powerful for theorem proving than weak typicality, can be applied to finite alphabets only, while weak typicality can be applied to countable alphabets. In this paper, the relation between typicality and information divergence measures is discussed. The new definition of information divergence measure in this paper leads to the definition of a unified typicality for finite or countably infinite alphabets which is stronger than both weak typicality and strong typicality. Unified typicality retains the asymptotic equipartition property and the structural properties of strong typicality, and it can potentially be used to generalize those theorems which are previously established by strong typicality to countable alphabets. The applications in rate-distortion theory and multisource network coding problems are discussed. © 2006 IEEE. Source


Zhou S.X.,Chinese University of Hong Kong | Chao X.,University of Michigan
Production and Operations Management | Year: 2014

We consider a periodic-review inventory system with regular and expedited supply modes. The expedited supply is faster than the regular supply but incurs a higher cost. Demand for the product in each period is random and sensitive to its selling price. The firm determines its order quantity from each supply in each period as well as its selling price to maximize the expected total discounted profit over a finite or an infinite planning horizon. We show that, in each period if it is optimal to order from both supplies, the optimal inventory policy is determined by two state-independent thresholds, one for each supply mode, and a list price is set for the product; if only the regular supply is used, the optimal policy is a state-dependent base-stock policy, that is, the optimal base-stock level depends on the starting inventory level, and the optimal selling price is a markdown price that decreases with the starting inventory level. We further study the operational impact of such supply diversification and show that it increases the firm's expected profit, reduces the optimal safety-stock levels, and lowers the optimal selling price. Thus that diversification is beneficial to both the firm and its customers. Building upon these results, we conduct a numerical study to assess and compare the respective benefit of dynamic pricing and supply diversification. © 2013 Production and Operations Management Society. Source


Lau N.-C.,Chinese University of Hong Kong
Bulletin of the American Meteorological Society | Year: 2016

The El Niño-Southern Oscillation (ENSO) phenomenon is one of the most prominent modes of atmospheric and oceanic variability on interannual and interdecadal time scales. The essential ENSO signals originate from the tropical Pacific (TP). However, the impacts of ENSO are felt in many other parts of the world. Major ENSO events are accompanied by notable changes in the extratropical atmospheric circulation in both hemispheres, various monsoon systems located beyond the TP, global air temperature and precipitation patterns, and the sea surface temperature (SST) distribution throughout the World Ocean. During the past several decades, this author has participated in a sustained effort to study the processes contributing to these "teleconnections" between ENSO forcing in the TP and variations in the atmosphere-ocean system elsewhere. These investigations are based on a large suite of experiments with several generations of general circulation models (GCMs) at the Geophysical Fluid Dynamics Laboratory (GFDL). These experiments are specifically designed to reveal various facets of the teleconnections with ENSO. In this lecture, a summary is given of the principal findings of this series of model studies. An account is given of the train of thought underpinning the sequence of experiments described herein, so as to illustrate how certain experimental setups have been motivated by the problem or hypothesis at hand. ©2016 American Meteorological Society. Source


Zhang J.,University of Macau | McBride-Chang C.,Chinese University of Hong Kong
Developmental Psychology | Year: 2014

A 4-stage developmental model, in which auditory sensitivity is fully mediated by speech perception at both the segmental and suprasegmental levels, which are further related to word reading through their associations with phonological awareness, rapid automatized naming, verbal short-term memory and morphological awareness, was tested with concurrently collected data on 153 2nd- and 3rd-grade Hong Kong Chinese children. Nested model comparisons were conducted to test this model separately against alternatives in relation to both Chinese and English word reading using structural equation modeling. For Chinese word reading, the proposed 4-stage model was demonstrated to be the best model. Auditory sensitivity was associated with speech perception, which was related to Chinese word reading mainly through its relations to morphological awareness and rapid automatized naming. In contrast, for English word reading, the best model required an additional direct path from suprasegmental sensitivity (in Chinese) to English word reading. That is, in addition to phonological awareness, Chinese speech prosody was also directly associated with English word recognition. © 2013 American Psychological Association. Source


Ng C.S.H.,Chinese University of Hong Kong
Journal of Thoracic Disease | Year: 2013

The history of uniportal Video-assisted thoracic surgery (VATS) stretches back almost a decade with the treatment of simple thoracic conditions. As the technique matures with increasing ability to tackle the full spectrum of thoracic surgical diseases, most notably major lung resections for lung tumours, the spread of uniportal VATS across the globe has been phenomenal. VATS centres in Asia are now performing uniportal VATS, and developing their individual styles and techniques with great successes. The enthusiasm from surgeons, demand from patients, as well as the dynamism and diversity of uniportal VATS in the region have helped fuel this excitement and change. The 1st Asian Single Port VATS Symposium in 2013 heralded the beginning of academic exchange between uniportal VATS centres in Asia and experts from around the world. Wetlabs in the region will provide further training for thoracic surgeons interested in super-specializing in uniportal VATS. The future of this approach will hinge on good regional collaboration, research and training. © Pioneer Bioscience Publishing Company. Source


Hu K.,CAS Institute of Atmospheric Physics | Huang G.,CAS Institute of Atmospheric Physics | Wu R.,Chinese University of Hong Kong
Journal of Climate | Year: 2013

The present study investigates the decadal change in the relationship between China high temperature extremes (HTEs) and El Niño-Southern Oscillation (ENSO). It is found that the relationship between the August HTEs in the southern Yangtze River valley (SYRV) and ENSO has strengthened since the late 1980s. Before the late 1980s, the relationship is weak, whereas, after the late 1980s, the August hot-day numbers in the SYRV region tend to be more than normal during El Niño decaying years. During 1988-2008, El Niño-induced August warm SST anomalies are mainly located in the eastern tropical and north Indian Ocean. As a response to the north Indian Ocean warming, the South Asia high extends eastward, and the SYRV is overlain by upper-level easterly anomalies. The cold horizontal temperature advection induced by upperlevel easterly anomalies leads to anomalous descent, which is conducive to the occurrence of HTEs through adiabatic warming. During 1966-86, El Niño-induced August warm SST anomalies are main y distributed in the equatorial central and southwest tropical Indian Ocean. Corresponding to the equatorial Indian Ocean warming, the ascending motion over the Arabian Sea is enhanced, which leads to an anomalous anticyclone over the Middle East through a Rossby wave-type response and in turn an anomalous cyclone over China through a midlatitude wave pattern. The SYRV is controlled by upper-level westerly anomalies, which is not conducive to the occurrence of HTEs since the corresponding horizontal temperature advection and anomalous vertical motion are weak. As such, the impact of ENSO on August SYRV HTEs is weak before the late 1980s. © 2013 American Meteorological Society. Source


Cheung D.,Chinese University of Hong Kong
Journal of Chemical Education | Year: 2011

One of the characteristics of teaching chemistry through inquiry is that teachers need to encourage students to design their experimental procedures. Although the benefits of inquiry teaching are well documented in the literature, few teachers implement it in schools. The purpose of this study was to develop a guided-inquiry scale (GIS) to measure teachers beliefs about implementing guided-inquiry labs in secondary schools. Construction of this guided-inquiry scale was based on a model with three dimensions: the value of guided-inquiry labs, limitations of cookbook-style labs, and implementation issues with guided-inquiry labs. Data were collected from 200 Hong Kong chemistry teachers. They responded to the GIS items using a seven-point Likert scale. The GIS data were of adequate reliability. Confirmatory factor analysis indicated that a good fit exists between the hypothesized model and data. Both users and nonusers of guided-inquiry labs valued this kind of lab work and recognized the limitations of cookbook-style labs; however, nonusers tended to believe that students dislike guided inquiry and it is not feasible for students to design experiments. The length of chemistry teaching experience and the level of student ability did not influence teachers beliefs about implementing guided-inquiry labs. © 2011 The American Chemical Society and Division of Chemical Education, Inc. Source


Chinese family members play an important role in end-of-life decision making. Culturally, they may believe that a patient's awareness of a poor prognosis could harm his or her well-being, and thus they may avoid telling the truth to the patient. To examine this cultural belief empirically, this study aimed to explore the relationships among the patient's awareness of the prognosis, the family's awareness of the prognosis, the patient's anxiety, and difficulty in communicating with family members. Clinical data mining was the research method. Clinical records of deceased cancer patients in the palliative care unit of a hospital during 2003-2005 were reviewed, and 935 patients were included in this study. Logistic regression analyses indicated that patients who did not have a clear awareness of their prognosis were more likely to experience anxiety (odds ratio [OR]=1.44, 95% CI=1.14-1.82, p=0.002) and difficulty communicating with family members (OR=2.11, 95% CI=1.62-2.76, p<0.001). Patients whose family members were less aware of the prognosis were more likely to experience difficulty communicating with family members (OR=4.48, 95% CI=1.93-10.42, p<0.001). This study further suggests that awareness of prognosis may not harm Chinese patients. Instead, unrealistic incomplete awareness of prognosis by patients and family members may be associated with patient anxiety and difficulty communicating. © Copyright 2011, Mary Ann Liebert, Inc. Source


Tsang J.Y.,Chinese University of Hong Kong
Breast cancer research and treatment | Year: 2013

The significance of chemokines in cancer biology has been widely recognized in recent years. CX3CL1 is a unique subclass of chemokine with complex functions, including recruitment of anti-tumor leukocytes and promoting cancer survival, thus affecting cancer progression in both the directions. It is not clear how these different functions interact in breast cancers. This is further complicated by the heterogeneity of breast cancer, and differential association of CX3CL1 with different subgroups could be present. There is only limited knowledge of CX3CL1 expression profile, its relationship with different biological features, subtypes, and outcomes in breast cancers. In this study, CX3CL1 expression was examined in a large cohort of breast cancers by immunohistochemistry and its association with clinicopathological factors, biomarker expression, and impact on patients' survival was assessed. High CX3CL1 expression was detected in 33.3 % (252/757) of primary invasive cancers. In line with its chemo-attractant function, CX3CL1 expression correlated positively with increased tumor infiltrating lymphocytes (TIL) (p = 0.005). In addition, CX3CL1 also correlated positively with adverse features in breast cancers, including lymph node involvement (p = 0.007), high Ki67 (p = 0.002), α-B crystallin expression (p = 0.008), and luminal B (worse prognosis luminal cancers) subtype (p = 0.024). Consistently, breast cancers with high expression of CX3CL1 were found to have a poorer overall survival (χ(2) = 4.797, p = 0.029). Interestingly, the adverse effect of CX3CL1 on outcome appeared to be more prominent in cancers with low TIL. These findings indicated that CX3CL1 could also have a pro-tumor role in breast cancer, despite its previously suggested role in enhancing anti-tumor immunity. The results highlighted the complicated functions of CX3CL1 in breast carcinogenesis. Further studies are needed to clarify the relative contribution of these anti- and pro-tumor functions in order to understand the true prognostic and potential therapeutic values of CX3CL1. Source


Ng J.L.W.,University of California at San Francisco | Chan M.T.V.,Chinese University of Hong Kong | Gelb A.W.,University of California at San Francisco
Anesthesiology | Year: 2011

Perioperative stroke after noncardiac, nonneurosurgical procedures is more common than generally acknowledged. It is reported to have an incidence of 0.05-7% of patients. Most are thrombotic in origin and are noted after discharge from the postanesthetic care unit. Common predisposing factors include age, a previous stroke, atrial fibrillation, and vascular and metabolic diseases. The mortality is more than two times greater than in strokes occurring outside the hospital. Delayed diagnosis and a synergistic interaction between the inflammatory changes normally associated with stroke, and those normally occurring after surgery, may explain this increase.Intraoperative hypotension is an infrequent direct cause of stroke. Hypotension will augment the injury produced by embolism or other causes, and this may be especially important in the postoperative period, during which monitoring is not nearly as attentive as in the operating room. Increased awareness and management of predisposing risk factors with early detection should result in improved outcomes. © 2011, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins. Anesthesiology. Source


Hildreth O.J.,Georgia Institute of Technology | Fedorov A.G.,Georgia Institute of Technology | Wong C.P.,Georgia Institute of Technology | Wong C.P.,Chinese University of Hong Kong
ACS Nano | Year: 2012

The ability to fabricate 3D spiraling structures using metal-assisted chemical etching (MaCE) is one of the unique advantages of MaCE over traditional etching methods. However, control over the chirality of the spiraling structures has not been established. In this work, a systematic parametric study was undertaken for MaCE of star-shaped catalysts, examining the influence of arm shape, arm length, number of arms, center core diameter, and catalyst thickness on the rotation direction. This data was used to identify a set of geometric parameters that reliably induce rotation in a predefined direction such that large arrays of 3D spiraling structures can be fabricated with the same chirality. Electroless deposition into the MaCE template was used to examine the full etch path of the catalyst and an experimental fit was established to control rotation angle by adjusting the catalyst's center core diameter. The ability to fabricate large arrays of 3D spiraling structures with predefined chirality could have important applications in photonics and optoelectronics. © 2012 American Chemical Society. Source


An X.,University College London | Yu J.C.,Chinese University of Hong Kong | Tang J.,University College London
Journal of Materials Chemistry A | Year: 2014

Novel copper (3 at%) doped SnS2 nanosheet-reduced graphene oxide (RGO) junctions were fabricated by a facile cysteine-assisted hydrothermal method. Superior visible-light-driven activity for methyl orange decomposition has been achieved. The average apparent rate of Cu-doped SnS2 nanosheet-RGO composites is more than 7 times higher than that of SnS 2, and even 2 times higher than CdS nanoparticles, the benchmark material. Further characterization indicates that facilitating charge separation, fast electron transport and a large surface area together play key roles in the materials enhanced photoactivity. Due to their chemical stability, low cost and lower toxicity, Cu-doped SnS2-RGO composites show great potential as high-efficiency visible-light-driven photocatalysts for environmental remediation and energy conversion. © 2014 The Royal Society of Chemistry. Source


Fan K.-W.,Chinese University of Hong Kong
Climatic Change | Year: 2010

In this article, the author reviews a number of recent publications by scientists and historians. Those publications, drawing on the latest scientific findings about climatic change in ancient China, suggest that the fall of the Tang and Ming dynasties may have been caused by global cooling. But the fall of a dynasty is a hugely complicated event. Lacking an adequate understanding of the relevant historical developments, the scholars under review fail to offer convincing explanations for imperial collapse. However, the author believes that when they are properly combined science and historical evidence can provide answers to important questions that history alone could not explain. © 2009 Springer Science+Business Media B.V. Source


Chan P.K.S.,Chinese University of Hong Kong
Cell and Bioscience | Year: 2012

Background: About 15 types of human papillomavirus (HPV) are classified as high-risk based on their epidemiological link with cervical cancer. These HPV types have deferent degrees of oncogenicity and their distribution among cervical precancers and cancers varies ethnogeographically. HPV58 is rare worldwide but being found more commonly in East Asia.Findings: A high prevalence of HPV58 among squamous cell carcinoma has been reported from China (28% in Shanghai, 10% in Hong Kong and 10% in Taiwan) and other countries in East Asia including Korea (16%) and Japan (8%). HPV58 ranks the third in Asia overall, but contributes to only 3.3% of cervical cancers globally. The reasons for a difference in disease attribution may lie on the host as well as the virus itself. HLA-DQB1*06 was found to associate with a higher risk of developing HPV58-positive cervical neoplasia in Hong Kong women, but not neoplasia caused by other HPV types. An HPV58 variant (E7 T20I, G63S) commonly detected in Hong Kong was found to confer a 6.9-fold higher risk of developing cervical cancer compared to other variants. A study involving 15 countries/cities has shown a predilection in the distribution of HPV58 variant lineages. Sublineage A1, the prototype derived from a cancer patient in Japan, was rare worldwide except in Asia.Conclusions: HPV58 accounts for a larger share of disease burden in East Asia, which may be a result of differences in host genetics as well as the oncogenicity of circulating variants. These unique characteristics of HPV58 should be considered in the development of next generation vaccines and diagnostic assays. © 2012 Chan; licensee BioMed Central Ltd. Source


Fang E.F.,Chinese University of Hong Kong
Protein and peptide letters | Year: 2010

Lectins, a class of proteins that reversibly and non-enzymatically bind specific sugars, have been purified from different kinds of legumes. In this study, a 48-kDa lectin (KBL) was purified from Korean large black soybeans using liquid chromatography. The specific hemagglutinating activity of the KBL was 4096 titer/mg. EDTA-induced loss of hemagglutinating activity of KBL could be recovered by addition of Fe(3+) ions and some divalent cations as Ca(2+), Mn(2+), Fe(2+), Cu(2+), Zn(2+), and Pb(2+). Sugars such as D-(+)-galactose, D-(+)-raffinose, L-(+)-arabinose, alpha-D-(+)-melibiose, and alpha-lactose could inhibit the hemagglutinating activity of the lectin. Furthermore, the protein showed high thermal stability as well as stability over a wide range of pH values. KBL inhibited HIV-1 reverse transcriptase activity with an IC(50) of 1.38 microM. However, it was destitute of cytokine releasing, mitogenic, ribonuclease and antifungal activities. In addition, inhibitory activity toward nasopharyngeal cell lines was undetectable in KBL at concentrations up to 20 microM. Source


Zeng S.,Nanyang Technological University | Baillargeat D.,Nanyang Technological University | Ho H.-P.,Chinese University of Hong Kong | Yong K.-T.,Nanyang Technological University
Chemical Society Reviews | Year: 2014

The main challenge for all electrical, mechanical and optical sensors is to detect low molecular weight (less than 400 Da) chemical and biological analytes under extremely dilute conditions. Surface plasmon resonance sensors are the most commonly used optical sensors due to their unique ability for real-time monitoring the molecular binding events. However, their sensitivities are insufficient to detect trace amounts of small molecular weight molecules such as cancer biomarkers, hormones, antibiotics, insecticides, and explosive materials which are respectively important for early-stage disease diagnosis, food quality control, environmental monitoring, and homeland security protection. With the rapid development of nanotechnology in the past few years, nanomaterials-enhanced surface plasmon resonance sensors have been developed and used as effective tools to sense hard-to-detect molecules within the concentration range between pmol and amol. In this review article, we reviewed and discussed the latest trend and challenges in engineering and applications of nanomaterials-enhanced surface plasmon resonance sensors (e.g., metallic nanoparticles, magnetic nanoparticles, carbon-based nanomaterials, latex nanoparticles and liposome nanoparticles) for detecting "hard-to- identify" biological and chemical analytes. Such information will be viable in terms of providing a useful platform for designing future ultrasensitive plasmonic nanosensors. © 2014 the Partner Organisations. Source


Lo C.F.,Chinese University of Hong Kong
Computational and Mathematical Methods in Medicine | Year: 2010

Based upon the deterministic Gompertz law of cell growth, we have proposed a stochastic model of tumour cell growth, in which the size of the tumour cells is bounded. The model takes account of both cell fission (which is an 'action at a distance' effect) and mortality too. Accordingly, the density function of the size of the tumour cells obeys a functional Fokker-Planck Equation (FPE) associated with the bounded stochastic process. We apply the Lie-algebraic method to derive the exact analytical solution via an iterative approach. It is found that the density function exhibits an interesting kink-like structure generated by cell fission as time evolves. © 2010 Taylor & Francis. Source


Yeung L.K.,Chinese University of Hong Kong
IEEE Transactions on Microwave Theory and Techniques | Year: 2011

A new dual-band 90 coupler using coupled transmission lines is proposed in this paper. As the coupler consists of only three quarter-wave coupled-line sections, it occupies less circuit area as compared to other existing dual-band branch-line couplers. A desired dual-band operation can be achieved by proper design of the coupling level for those coupled-line sections. Moreover, the coupler's configuration contains a degree of freedom so that its design is customizable, allowing itself to be conveniently realized on a variety of circuit and substrate technologies. As a result, it is suitable for use in many practical applications. © 2011 IEEE. Source


Cheng K.C.K.,Chinese University of Hong Kong | Yap R.H.C.,National University of Singapore
Constraints | Year: 2010

A table constraint is explicitly represented as its set of solutions or non-solutions. This ad hoc (or extensional) representation may require space exponential to the arity of the constraint, making enforcing GAC expensive. In this paper, we address the space and time inefficiencies simultaneously by presenting the mddc constraint. mddc is a global constraint that represents its (non-)solutions with a multi-valued decision diagram (MDD). The MDD-based representation has the advantage that it can be exponentially smaller than a table. The associated GAC algorithm (called mddc) has time complexity linear to the size of the MDD, and achieves full incrementality in constant time. In addition, we show how to convert a positive or negative table constraint into an mddc constraint in time linear to the size of the table. Our experiments on structured problems, car sequencing and still-life, show that mddc is also a fast GAC algorithm for some global constraints such as sequence and regular. We also show that mddc is faster than the state-of-the-art generic GAC algorithms in Gent et al. (2007), Lecoutre and Szymanek (2006), Lhomme and Régin (2005) for table constraint. © Springer Science+Business Media, LLC 2009. Source


Lai D.Y.F.,Chinese University of Hong Kong
Ecological Engineering | Year: 2014

This study investigated the distribution of phosphorus (P) fractions in soils, and the magnitude and seasonal variations of P flux across the soil-water interface at the Hong Kong Wetland Park (HKWP), the largest free surface flow constructed wetland in the territory. Iron-bound P was the dominant P form comprising 29-59% of the total soil P, and its concentration was considerably lower than that in a nearby eutrophic marsh. The HKWP soils demonstrated a mean P release of 0.05±0.01mgm-2d-1, which was very low compared with the range reported for other constructed wetlands. Significantly higher soil P fluxes were obtained under anaerobic conditions that could possibly be attributed to the release of redox-sensitive iron-bound P to the overlying water column. Moreover, soil P flux was significantly higher in the dry season than the wet season, which was likely a result of differences in water column P concentration and hence diffusive flux. These findings suggest that the HKWP soils comprising fishpond bund materials, river sand and decomposed granite would not contribute to significant degradation in water quality. © 2014 Elsevier B.V. Source


Chen S.-C.,Chinese University of Hong Kong | Culpepper M.L.,Massachusetts Institute of Technology
Journal of Microelectromechanical Systems | Year: 2012

This paper presents the concepts, models, and experimental validations of the geometric contouring method and a pulsing technique to enhance dynamic performance of micro thermomechanical actuators (μ TMAs). For a typical TMA, contouring may improve its stroke, force, and speed performances by a factor of 4, 2.5, and 10, respectively. In the meantime, the required power for achieving the same performance is reduced by 40%. Herein, we show the following: 1) how to obtain marked dynamic and static performance from μ TMAs 2) how to model and optimize these improvements; and 3) how to use transient electrical command signals to augment these improvements. The utility and practical implementation of these techniques are illustrated via a case study on a stage from a three-axis optical scanner for a two-photon endomicroscope. © 2012 IEEE. Source


Wang D.H.,Chongqing University | Liao W.H.,Chinese University of Hong Kong
Smart Materials and Structures | Year: 2011

Due to the inherent nonlinear nature of magnetorheological (MR) dampers, one of the challenging aspects for developing and utilizing these devices to achieve high performance is the development of models that can accurately describe their unique characteristics. In this review, the characteristics of MR dampers are summarized according to the measured responses under different conditions. On these bases, the considerations and methods of the parametric dynamic modelling for MR dampers are given and the state-of-the-art parametric dynamic modelling, identification and validation techniques for MR dampers are reviewed. In the past two decades, the models for MR dampers have been focused on how to improve the modelling accuracy. Although the force-displacement behaviour is well represented by most of the proposed dynamic models for MR dampers, no simple parametric models with high accuracy for MR dampers can be found. In addition, the parametric dynamic models for MR dampers with on-line updating ability and the inverse parametric models for MR dampers are scarcely explored. Moreover, whether one dynamic model for MR dampers can portray the force-displacement and force-velocity behaviour is not only determined by the dynamic model itself but also determined by the identification method. Source


Luo Z.-Q.,University of Minnesota | Zhang S.,Chinese University of Hong Kong
SIAM Journal on Optimization | Year: 2010

We present a general semidefinite relaxation scheme for general n-variate quartic polynomial optimization under homogeneous quadratic constraints. Unlike the existing sum-ofsquares approach which relaxes the quartic optimization problems to a sequence of (typically large) linear semidefinite programs (SDP), our relaxation scheme leads to a (possibly nonconvex) quadratic optimization problem with linear constraints over the semidefinite matrix cone in R n×n. It is shown that each α-factor approximate solution of the relaxed quadratic SDP can be used to generate in randomized polynomial time an O(α)-factor approximate solution for the original quartic optimization problem, where the constant in O(-) depends only on problem dimension. In the case where only one positive definite quadratic constraint is present in the quartic optimization problem, we present a randomized polynomial time approximation algorithm which can provide a guaranteed relative approximation ratio of (1 - O(n-2)). Copyright © 2010, Society for Industrial and Applied Mathematics. Source


Gao J.,Shanghai JiaoTong University | Li D.,Chinese University of Hong Kong
Operations Research | Year: 2013

One long-standing challenge in both the optimization and investment communities is to devise an efficient algorithm to select a small number of assets from an asset pool such that a portfolio objective is optimized. This cardinality constrained investment situation naturally arises due to the presence of various forms of market friction, such as transaction costs and management fees, or even due to the consideration of mental cost. Unfortunately, the combinatorial nature of such a portfolio selection problem formulation makes the exact solution process NP-hard in general. We focus in this paper on the cardinality constrained mean-variance portfolio selection problem. Instead of tailoring such a difficult problem into the general solution framework of mixed-integer programming formulation, we explore the special structures and rich geometric properties behind the mathematical formulation. Applying the Lagrangian relaxation to the primal problem results in a pure cardinality constrained portfolio selection problem, which possesses a symmetric property, and to which geometric approaches can be developed. Different from the existing literature that has primarily focused on some direct relaxations of the cardinality constraint, we consider modifying the objective function to some separable relaxations, which are immune to the hard cardinality constraint. More specifically, we develop efficient lower bounding schemes by using the circumscribed box, the circumscribed ball, and the circumscribed axis-aligned ellipsoid to approximate the objective contour of the problem. In particular, all these cardinality constrained relaxation problems can be solved analytically. Furthermore, we derive efficient polynomial-time algorithms for the corresponding dual search problems. Most promisingly, the lower bounding scheme using the circumscribed axis-aligned ellipsoid leads to a semidefinite programming (SDP) formulation and offers a sharp bound and high-quality feasible solution. By integrating these lower bounding schemes into a branch-and-bound algorithm (BnB), our solution scheme outperforms CPLEX significantly in identifying the exact optimal portfolio. ©2013 INFORMS. Source


Li L.,Chinese University of Hong Kong | Linetsky V.,Northwestern University
Operations Research | Year: 2013

This paper proposes a new approach to solve finite-horizon optimal stopping problems for a class of Markov processes that includes one-dimensional diffusions, birth-death processes, and jump diffusions and continuous-time Markov chains obtained by time-changing diffusions and birth-and-death processes with Lévy subordinators. When the expectation operator has a purely discrete spectrum in the Hilbert space of square-integrable payoffs, the value function of a discrete optimal stopping problem has an expansion in the eigenfunctions of the expectation operator. The Bellman's dynamic programming for the value function then reduces to an explicit recursion for the expansion coefficients. The value function of the continuous optimal stopping problem is then obtained by extrapolating the value function of the discrete problem to the limit via Richardson extrapolation. To illustrate the method, the paper develops two applications: American-style commodity futures options and Bermudan-style abandonment and capacity expansion options in commodity extraction projects under the subordinate Ornstein-Uhlenbeck model with mean-reverting jumps with the value function given by an expansion in Hermite polynomials. ©2013 INFORMS. Source


Zheng X.Y.,Yunnan University | Ng K.F.,Chinese University of Hong Kong
SIAM Journal on Optimization | Year: 2010

This paper concerns a generalized equation defined by a closed multifunction between Banach spaces, and we employ variational analysis techniques to provide sufficient and/or necessary conditions for a generalized equation to have the metric subregularity (i.e., local error bounds for the concerned multifunction) in general Banach spaces. Following the approach of Ioffe [Trans. Amer. Math. Soc., 251 (1979), pp. 61-69] who studied the numerical function case, our conditions are described in terms of coderivatives of the concerned multifunction at points outside the solution set. Motivated by the existing modulus representation and point-based criteria for the metric regularity, we establish the corresponding results for the metric subregularity. In the Asplund space case, sharper results are obtained. © 2010 Society for Industrial and Applied Mathematics. Source


Fu X.,Chinese Academy of Sciences | Wang H.,Chinese University of Hong Kong | Hu P.,Chinese Academy of Sciences
Cellular and Molecular Life Sciences | Year: 2015

Muscle stem cell (satellite cell) activation post muscle injury is a transient and critical step in muscle regeneration. It is regulated by physiological cues, signaling molecules, and epigenetic regulatory factors. The mechanisms that coherently turn on the complex activation process shortly after trauma are just beginning to be illuminated. In this review, we will discuss the current knowledge of satellite cell activation regulation. © 2015 The Author(s). Source


Chen B.-B.,Chinese University of Hong Kong
School Psychology International | Year: 2011

This study examined the influences of peer interpersonal strategy and secure attachment on social status in peer contexts in the initial period of secondary school in China. Two hundred and thirty-one new students in secondary schools (grade 6) were recruited in the first semester to complete measures of interpersonal strategies in the peer group, secure attachment to mother, social dominance, and sociometric nomination. The results indicated that both prosocial strategies and attachment security were positively correlated with social dominance and peer preference in peer group, whereas the coercive strategies were not correlated with social status. Implications and limitations of findings were discussed. © The Author(s) 2011. Source


Bernstein C.N.,University of Manitoba | Loftus Jr. E.V.,Mayo Medical School | Ng S.C.,Chinese University of Hong Kong | Lakatos P.L.,Semmelweis University | Moum B.,University of Oslo
Gut | Year: 2012

Hospitalisation and surgery are considered to be markers of more severe disease in Crohn's disease. These are costly events and limiting these costs has emerged as one rationale for the cost of expensive biologic therapies. The authors sought to review the most recent international literature to estimate current hospitalisation and surgery rates for Crohn's disease and place them in the historical context of where they have been, whether they have changed over time, and to compare these rates across different jurisdictions. It is in this context that the authors could set the stage for interpreting some of the early data and studies that will be forthcoming on rates of hospitalisation and surgery in an era of more aggressive biologic therapy. The most recent data from Canada, the United Kingdom and Hungary all suggest that surgical rates were falling prior to the advent of biologic therapy, and continue to fall during this treatment era. The impact of biologic therapy on surgical rates will have to be analysed in the context of evolving reductions in developed regions before biologic therapy was even introduced. Whether more aggressive medical therapy will decrease the requirement for surgery over long periods of time remains to be proven. Source


Tong Y.,Chinese University of Hong Kong
Journal of Sex Research | Year: 2013

Asian American youth are less likely to be sexually active than adolescents from other ethnic groups; however, with acculturation, they may adopt the more liberal sexual norms of American society. Moreover, owing to differing parental expectations for sons and daughters about sexuality, gender disparity might exist in the adoption of American sexual norms. This article used the proportional hazards model and the generalized estimating equations Poisson model to examine how acculturation influences the initiation of sexual intercourse and the number of sexual partners. The results show that acculturation leads to more liberal sexual mores among Asian American youth. However, despite what might be expected from the sexual double standard, the models show that more acculturated females, as indicated by their use of English at home, had an earlier onset of sexual intercourse and a higher number of sexual partners. This is the opposite of what would be predicted by the sexual double standard theory. This might be due to the fact that Asian females tend to be more socially accepted by the host society than Asian males. Information on partners shows that Asian American females have more diversified racial backgrounds than their male counterparts. They are also more likely to have older sexual partners. Copyright © The Society for the Scientific Study of Sexuality. Source


Song Z.,CAS Shenzhen Institutes of Advanced Technology | Chung R.,Chinese University of Hong Kong
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2010

Position and orientation profiles are two principal descriptions of shape in space. We describe how a structured light system, coupled with the illumination of a pseudorandom pattern and a suitable choice of feature points, can allow not only the position but also the orientation of individual surface elements to be determined independently. Unlike traditional designs which use the centroids of the illuminated pattern elements as the feature points, the proposed design uses the grid points between the pattern elements instead. The grid points have the essences that their positions in the image data are inert to the effect of perspective distortion, their individual extractions are not directly dependent on one another, and the grid points possess strong symmetry that can be exploited for their precise localization in the image data. Most importantly, the grid lines of the illuminated pattern that form the grid points can aid in determining surface normals. In this paper, we describe how each of the grid points can be labeled with a unique color code, what symmetry they possess and how the symmetry can be exploited for their precise localization at subpixel accuracy in the image data, and how 3D orientation in addition to 3D position can be determined at each of them. Both the position and orientation profiles can be determined with only a single pattern illumination and a single image capture. © 2006 IEEE. Source


Yu C.-M.,Chinese University of Hong Kong | Hayes D.L.,Mayo Medical School
European Heart Journal | Year: 2013

Cardiac resynchronization therapy (CRT) is currently an established device therapy for heart failure (HF) patients. Cumulated knowledge on the pathophysiological mechanisms, implantation techniques, advancement of device-based technologies, and clinical trial experience has impacted on this evolving therapy significantly in the last few years. This article will address the updated CRT guideline and potentially new indications of CRT such as patients with New York Heart Association Class I, normal QRS duration, and non-HF patients with pacing indications. Furthermore, important but unresolved issues will also be discussed which include the impact of QRS morphology and QRS duration on CRT response, new approaches for placement of left ventricular (LV) lead, multisite LV pacing, and the role of HF disease monitoring program. © 2013 Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2013. For permissions please email: journals.permissions@oup.com. Source


Du J.,Shanghai JiaoTong University | Shu C.,Chinese University of Hong Kong
Journal of Lightwave Technology | Year: 2013

With cascaded and multisection Sagnac interferometers, all-optical fast Fourier transform (FFT) has been demonstrated for optical demultiplexing (DEMUX) of orthogonal frequency division multiplexing (OFDM) signals. The transmission characteristics of the interferometers have been investigated theoretically and experimentally. The scalability and tunability of the all-optical OFDM DEMUX are analyzed and demonstrated for 5-channel OFDM signals. © 1983-2012 IEEE. Source


Li H.,University of Electronic Science and Technology of China | Ngan K.N.,Chinese University of Hong Kong
IEEE Transactions on Image Processing | Year: 2011

In this paper, we introduce a method to detect co-saliency from an image pair that may have some objects in common. The co-saliency is modeled as a linear combination of the single-image saliency map (SISM) and the multi-image saliency map (MISM). The first term is designed to describe the local attention, which is computed by using three saliency detection techniques available in literature. To compute the MISM, a co-multilayer graph is constructed by dividing the image pair into a spatial pyramid representation. Each node in the graph is described by two types of visual descriptors, which are extracted from a representation of some aspects of local appearance, e.g., color and texture properties. In order to evaluate the similarity between two nodes, we employ a normalized single-pair SimRank algorithm to compute the similarity score. Experimental evaluation on a number of image pairs demonstrates the good performance of the proposed method on the co-saliency detection task. © 2006 IEEE. Source


Ng C.-K.,Chinese University of Hong Kong
Physics Education | Year: 2015

We analyse why it is erroneous to think that a tidal bulge is formed by pulling the water surface directly up by a local vertical tidal force. In fact, ocean tides are caused by the global effect of the horizontal components of the tidal forces. © 2015 IOP Publishing Ltd Source


Sung-Chan P.,Hong Kong Polytechnic University | Sung Y.W.,Chinese University of Hong Kong | Zhao X.,Tongji University | Brownson R.C.,Washington University in St. Louis
Obesity Reviews | Year: 2013

Effective interventions are needed to address the growing epidemic of childhood obesity. In the past 35 years, family-based approach has gradually developed as a preferred intervention. This review aimed to examine the methodological rigour and treatment effectiveness of family-based interventions according to intervention types and theoretical orientations. A total of 15 randomized controlled trials (RCTs) of family-based lifestyle interventions for children and adolescents aged 2-19 years were included. The adapted Methodological Quality Rating Scales (MQRS) and a four-grade qualitative scoring scheme were adopted to evaluate the methodological rigour and the effectiveness of treatment, respectively. The average MQRS score was 7.93 out of 14 points. Ten of the 15 RCTs had well aligned their research questions with appropriate research methods. The overall short-term outcome of the15 RCTs were satisfactory with an average score of 3.1. Family-based interventions rooted in behaviour theory achieved better results than those theoretically connected to family systems theory in terms of treatment effectiveness. Results suggest future studies to improve the methodological design and continue to explore the potential of the family systems approach. © 2012 The Authors. Obesity Reviews. © 2012 International Association for the Study of Obesity. Source


Li P.K.T.,Chinese University of Hong Kong | Burdmann E.A.,University of Sao Paulo | Mehta R.L.,University of California at San Diego | Martin S.,World Kidney Day Global Operations Center
Kidney International | Year: 2013

Acute kidney injury (AKI) is increasingly prevalent in developing and developed countries and is associated with severe morbidity and mortality. Most etiologies of AKI can be prevented by interventions at the individual, community, regional, and in-hospital levels. Effective measures must include community-wide efforts to increase an awareness of the devastating effects of AKI and provide guidance on preventive strategies, as well as early recognition and management. Efforts should be focused on minimizing causes of AKI, increasing awareness of the importance of serial measurements of serum creatinine in high-risk patients, and documenting urine volume in acutely ill people to achieve early diagnosis; there is as yet no definitive role for alternative biomarkers. Protocols need to be developed to systematically manage prerenal conditions and specific infections. More accurate data about the true incidence and clinical impact of AKI will help to raise the importance of the disease in the community, increase awareness of AKI by governments, the public, general and family physicians, and other health-care professionals to help prevent the disease. Prevention is the key to avoid the heavy burden of mortality and morbidity associated with AKI. © 2012 International Society of Nephrology. Source


Wang J.,Chinese University of Hong Kong
Macromolecules | Year: 2015

Besides the fast translational diffusion of individual chains, a slow relaxation mode is frequently observed in dilute poly(ethylene oxide) (PEO) aqueous solutions in dynamic laser light scattering (LLS) experiments, which was attributed to some hydrophobic impurities in PEO or interchain association. Recently, we also encountered such a slow mode when studying dilute solutions of star-like PEO chains in water, hindering our further study of their dynamics in semidilute solutions. Using a combination of static and dynamic LLS, we found that the slow mode is removable after repeated filtration through a hydrophilic 0.45 ∼m PTFE filter or heating at 55 °C, resulting in a stable solution with only one fast translational mode of individual chains even after 5 months. Further, we found that an injection of a small amount of air regenerated the slow mode, revealing its origin, small air bubbles stabilized by the PEO chains adsorbed at the air/water interface, not previously proposed impurities or equilibrium between large interchain aggregates and individual chains. Our result has clarified a long-standing confusion of whether PEO is completely soluble in water as individual chains at room temperature. Our finding is important since aqueous solutions of PEO and its copolymers are widely used as model systems in academic research and as important ingredients in various industrial applications. © 2015 American Chemical Society. Source


Liu L.,University of Nottingham | Chen Z.,University of Newcastle | Huang J.,Chinese University of Hong Kong
IEEE Transactions on Automatic Control | Year: 2011

In this technical note, we study the global disturbance rejection problem of nonlinear systems in lower triangular form with unknown exosystem via state feedback control. The problem is dealt with in two steps. In the first step, an augmented system composed of the given plant and an internal model is constructed. Owing to the presence of the unknown parameter in the exosystem, the augmented system contains both nonlinearly and linearly parameterized uncertainties. In the second step, the stabilization of the augmented system is solved by an approach integrating both robust and adaptive techniques. The solution of the stabilization problem of the augmented system in turn leads to the solution of the global disturbance rejection problem of the original system. Further, the convergence issue of an estimated unknown parameter vector is also discussed. © 2011 IEEE. Source


Zhang B.,Beihang University | Gao Y.,Griffith University | Zhao S.,Griffith University | Liu J.,Chinese University of Hong Kong
IEEE Transactions on Image Processing | Year: 2010

This paper proposes a novel high-order local pattern descriptor, local derivative pattern (LDP), for face recognition. LDP is a general framework to encode directional pattern features based on local derivative variations. The nth-order LDP is proposed to encode the (n-1)th-order local derivative direction variations, which can capture more detailed information than the first-order local pattern used in local binary pattern (LBP). Different from LBP encoding the relationship between the central point and its neighbors, the LDP templates extract high-order local information by encoding various distinctive spatial relationships contained in a given local region. Both gray-level images and Gabor feature images are used to evaluate the comparative performances of LDP and LBP. Extensive experimental results on FERET, CAS-PEAL, CMU-PIE, Extended Yale B, and FRGC databases show that the high-order LDP consistently performs much better than LBP for both face identification and face verification under various conditions. © 2010 IEEE. Source


Duan L.,Singapore University of Technology and Design | Huang J.,Chinese University of Hong Kong | Shou B.,City University of Hong Kong
IEEE Transactions on Mobile Computing | Year: 2013

Femtocells can effectively resolve the poor connectivity issue of indoor cellular users. This paper investigates the economic incentive for a cellular operator to add femtocell service on top of its existing macrocell service. We model the interactions between a cellular operator and users as a Stackelberg game: The operator first determines spectrum allocations and pricings of femtocell and macrocell services, and then heterogeneous users choose between the two services and the amount of resource to request. In the ideal case where the femtocell service has the same full spatial coverage as the macrocell service, we show that the operator will choose to provide femtocell service only, as this leads to a better user quality of service and a higher operator profit. However, if we impose the constraint that no users' payoffs decrease after introducing the femtocell service, then the operator will always continue providing the macrocell service (with or without the femtocell service). Furthermore, we study the impact of operational cost, limited coverage, and spatial reuse on femtocell service provision. As the operational cost increases, fewer users are served by femtocell service and the operator's profit decreases. When the femtocell service has limited spatial coverage, the operator always provides the macrocell service beside the femtocell service. However, when the coverage is high or the total resource is low, the operator will set the prices such that all users who can access femtocell will choose to use the femtocell service only. Finally, spatial reuse of spectrum will increase the efficiency of femtocell services and gives the operator more incentives to allocate spectrum to femtocells. © 2002-2012 IEEE. Source


Chen X.,Arizona State University | Huang J.,Chinese University of Hong Kong
IEEE Journal on Selected Areas in Communications | Year: 2013

Efficient distributed spectrum sharing mechanism is crucial for improving the spectrum utilization. The spatial aspect of spectrum sharing, however, is less understood than many other aspects. In this paper, we generalize a recently proposed spatial congestion game framework to design efficient distributed spectrum access mechanisms with spatial reuse. We first propose a spatial channel selection game to model the distributed channel selection problem with fixed user locations. We show that the game is a potential game, and develop a distributed learning mechanism that converges to a Nash equilibrium only based on users' local observations. We then formulate the joint channel and location selection problem as a spatial channel selection and mobility game, and show that it is also a potential game. We next propose a distributed strategic mobility algorithm, jointly with the distributed learning mechanism, that can converge to a Nash equilibrium. © 1983-2012 IEEE. Source


Yan Y.,Tsinghua National Laboratory for Information Sciences and Technology | Huang J.,Chinese University of Hong Kong | Wang J.,Tsinghua National Laboratory for Information Sciences and Technology
IEEE Journal on Selected Areas in Communications | Year: 2013

Cooperative spectrum sharing can effectively improve the spectrum usage by allowing secondary users (SUs) to dynamically and opportunistically share the licensed bands with primary users (PUs). In return, an SU will relay a PU's traffic to improve the PU's effective data rate. In this paper, we study how one PU and one SU achieve an efficient spectrum sharing through dynamic noncooperative bargaining. The key challenge is that the PU does not have complete information of the SU's energy cost. We model the dynamic bargaining with incomplete information as a dynamic Bayesian game, and investigate the equilibria under both single-slot and multi-slot bargaining models. Theoretical analysis and numerical results indicate that our proposed scheme can lead to a win-win situation, where both the PU and the SU obtain data rate improvements via the bargaining-based CSS mechanism. Furthermore, the SU can take advantage of the incomplete information to improve its bargaining power (also called reputation effect), and thus gain a higher data rate. © 2013 IEEE. Source


Chiu M.C.,The Hong Kong Institute of Education | Wong H.Y.,Chinese University of Hong Kong
Operations Research Letters | Year: 2013

Using the diffusion limit of the discrete-time error correction model of cointegration for risky assets and geometric Brownian motion for the value of liabilities, we solve the asset-liability management (ALM) problem using the theory of backward stochastic differential equations. The solutions of the ALM policy and the efficient frontier in terms of surplus are obtained as closed-form formulas. We numerically examine the impact of cointegration to the trade-off between risk and return in managing cointegrated risky assets and random liabilities. © 2012 Elsevier B.V. All rights reserved. Source


Huang J.,Chinese University of Hong Kong
IEEE Communications Magazine | Year: 2013

Wireless spectrum is very valuable but currently heavily under-utilized. Cooperative spectrum trading encourages primary licensed users and secondary unlicensed users to exchange money or resources to achieve a win-win situation, and can significantly increase the utilization of wireless spectrum. In this article, we discuss various market mechanisms that facilitate cooperative spectrum trading with incomplete network information. We introduce mechanisms including pricing, bargaining, contract, and auction, and demonstrate the applicability using a concrete example of resource-exchange cooperative spectrum trading. We also outline various open issues in this emerging interdisciplinary research area. © 2013 IEEE. Source


Hetsch F.,City University of Hong Kong | Zhao N.,Chinese University of Hong Kong | Kershaw S.V.,City University of Hong Kong | Rogach A.L.,City University of Hong Kong
Materials Today | Year: 2013

Solution processed colloidal semiconductor quantum dots offer a high potential for decreasing costs and expanding versatility of many electronic and optoelectronic devices. Initially used as a research tool to study charge carrier mobilities in closely packed quantum dot thin films, field effect transistors with quantum dots as the active layer have recently experienced a breakthrough in performance (achievement of mobilities higher than 30 cm 2 V-1 s-1) as a result of a proper choice of surface ligands and/or improved chemical treatment of the nanoparticle films during device processing. Here we review these innovative developments and the continuing work that may soon lead to commercial grade electronic components. © 2013 Elsevier Ltd. Source


Mak M.-H.,Chinese University of Hong Kong
Omega (United States) | Year: 2012

One of the main responsibilities of teachers is to help individual students cope with life difficulties such as grief following a death. However, very little research explores teachers' views on death, dying, and how they handle grief and loss in schools. This study aims to explore university teachers' knowledge and attitudes on dying, death, and death education. Fifteen university teachers were recruited using a qualitative method. This study reveals that most teachers' views on death and related issues are largely affected by their death experiences, religious beliefs, professional background, and the mass media. Although they have a general negative response toward death and dying, some teachers begin to affirm their meanings of life and death. Most teachers agree that they do not feel adequate about managing and teaching on life and death issues, so they strongly support including death education in the formal programs in Hong Kong. © 2013, Baywood Publishing Co., Inc. Source


Chen J.-K.,Chinese University of Hong Kong | Wei H.-S.,National Taipei University
Child Abuse and Neglect | Year: 2011

This paper reports on the prevalence of student victimization by teachers in junior high schools in a Chinese cultural context (Taiwan) and examines how student demographic variables (gender, grade level, and family socioeconomic status) and school social experiences (student-teacher relationships and involvement with at-risk peers) are associated with such victimization. Methods: Data were obtained from a large-scale random sample of 1,376 junior-high students (grades 7-9) in the city of Taichung, Taiwan. Students were given an anonymous structured questionnaire, including items regarding basic demographics and school social experiences. Results: Overall, 26.9% of students reported having been maltreated by teachers at least 1 time in the previous semester. Hitting, beating, or slapping was the most common maltreatment, and the most vulnerable students were boys and senior students. Students who perceived that student-teacher relationships were poor, and those who were involved with at-risk peers, were more likely to report victimization. Conclusion: Although there are clear guidelines and regulations prohibiting teacher aggression against students, Taiwanese students are still exposed to high levels of maltreatment. The findings provide empirical evidence to support school social workers and policymakers in taking immediate action to educate politicians, the general public, and the media about the severity of student victimization by teachers as well as to build up mechanisms to supervise the government's enforcement of regulation. These findings clearly imply that promoting positive social experiences for students is crucial for successful intervention. © 2011 Elsevier Ltd. Source


HIV is a serious health threat among men who have sex with men (MSM). A 2-month pilot network-based peer intervention was conducted among Chinese MSM in Hong Kong. Eight MSM peer educators were randomized into the Intervention or the Control Groups and recruited 36 and 33 peers to join the program, respectively. The educators of the Intervention Group delivered standardized and theory-based preventive messages to their peers via daily social interactions. The Control Group received education materials. Baseline between-group differences were non-significant. At post-intervention, intervened participants were more likely than controlled participants to intend to use condoms consistently during anal sex with men in the next 6 months [94.4% versus 60.6%; Relative Risk (RR): 1.56 (95% Confidence Interval (CI): 1.17, 2.08)] and to perceive behavioral control over taking up voluntary HIV testing and counseling [97.2% versus 72.7%; RR: 1.34 (95% CI: 1.08, 1.66)]. Large scale randomized trials are warranted. Source


Marmor M.F.,Stanford University | Kellner U.,AugenZentrum Siegburg | Lai T.Y.Y.,Chinese University of Hong Kong | Lyons J.S.,Georgetown University | Mieler W.F.,University of Illinois at Chicago
Ophthalmology | Year: 2011

Background The American Academy of Ophthalmology recommendations for screening of chloroquine (CQ) and hydroxychloroquine (HCQ) retinopathy were published in 2002, but improved screening tools and new knowledge about the prevalence of toxicity have appeared in the ensuing years. No treatment exists as yet for this disorder, so it is imperative that patients and their physicians be aware of the best practices for minimizing toxic damage. Risk of Toxicity New data have shown that the risk of toxicity increases sharply toward 1% after 5 to 7 years of use, or a cumulative dose of 1000 g, of HCQ. The risk increases further with continued use of the drug. Dosage The prior recommendation emphasized dosing by weight. However, most patients are routinely given 400 mg of HCQ daily (or 250 mg CQ). This dose is now considered acceptable, except for individuals of short stature, for whom the dose should be determined on the basis of ideal body weight to avoid overdosage. Screening Schedule A baseline examination is advised for patients starting these drugs to serve as a reference point and to rule out maculopathy, which might be a contraindication to their use. Annual screening should begin after 5 years (or sooner if there are unusual risk factors). Screening Tests Newer objective tests, such as multifocal electroretinogram (mfERG), spectral domain optical coherence tomography (SD-OCT), and fundus autofluorescence (FAF), can be more sensitive than visual fields. It is now recommended that along with 10-2 automated fields, at least one of these procedures be used for routine screening where available. When fields are performed independently, even the most subtle 10-2 field changes should be taken seriously and are an indication for evaluation by objective testing. Because mfERG testing is an objective test that evaluates function, it may be used in place of visual fields. Amsler grid testing is no longer recommended. Fundus examinations are advised for documentation, but visible bulls-eye maculopathy is a late change, and the goal of screening is to recognize toxicity at an earlier stage. Counseling Patients should be aware of the risk of toxicity and the rationale for screening (to detect early changes and minimize visual loss, not necessarily to prevent it). The drugs should be stopped if possible when toxicity is recognized or strongly suspected, but this is a decision to be made in conjunction with patients and their medical physicians. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references. © 2011 American Academy of Ophthalmology. Source


Chen X.,Arizona State University | Huang J.,Chinese University of Hong Kong
IEEE Transactions on Mobile Computing | Year: 2013

In this paper, we design distributed spectrum access mechanisms with both complete and incomplete network information. We propose an evolutionary spectrum access mechanism with complete network information, and show that the mechanism achieves an equilibrium that is globally evolutionarily stable. With incomplete network information, we propose a distributed learning mechanism, where each user utilizes local observations to estimate the expected throughput and learns to adjust its spectrum access strategy adaptively over time. We show that the learning mechanism converges to the same evolutionary equilibrium on the time average. Numerical results show that the proposed mechanisms achieve up to 35 percent performance improvement over the distributed reinforcement learning mechanism in the literature, and are robust to the perturbations of users' channel selections. © 2002-2012 IEEE. Source


Ng P.C.,Chinese University of Hong Kong
Journal of Pediatrics | Year: 2011

The hypothalamic-pituitary-adrenal (HPA) axis is essential for maintaining homeostasis in the fetus and newborn. A proportion of extremely preterm infants suffer from transient adrenocortical insufficiency of prematurity. Although these infants have suboptimal adrenocortical response to stress in the first week of life, the HPA axis adapts rapidly, and most exhibit an adequate response by day 14. An attenuated cortisol response in preterm infants might be protective against intracranial bleeding. Severe hypoxic-ischemic encephalopathy is a potent stimulus to the HPA axis. Chronic intrauterine hypoxemia can up-regulate the setpoint of the HPA axis and augments adrenal steroidogenic production, resulting in sustained elevation of circulating cortisol levels. © 2011 Mosby Inc. All rights reserved. Source


Wu C.,Chinese University of Hong Kong
Macromolecular Chemistry and Physics | Year: 2013

Aside from making existing catalysts and polymerization conditions optimal, polymer chemists should focus on developing new catalysts, new synthetic methods, and new polymerization processes. An area that should be of particular interest is that of bio-catalysts and bio-synthesis because of the inevitable exhaustion of crude oils and natural gases on which the modern polymer industry has been built. For polymer physics, the focus should still lie in the development of novel methodologies to solve remaining fundamental problems that are related to polymer processes by concentrating on correlations between polymer properties and chain structures as well as process conditions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Leung C.C.,Center for Health Protection | Yu I.T.S.,Chinese University of Hong Kong | Chen W.,Huazhong University of Science and Technology
The Lancet | Year: 2012

Silicosis is a fibrotic lung disease caused by inhalation of free crystalline silicon dioxide or silica. Occupational exposure to respirable crystalline silica dust particles occurs in many industries. Phagocytosis of crystalline silica in the lung causes lysosomal damage, activating the NALP3 inflammasome and triggering the inflammatory cascade with subsequent fibrosis. Impairment of lung function increases with disease progression, even after the patient is no longer exposed. Diagnosis of silicosis needs carefully documented records of occupational exposure and radiological features, with exclusion of other competing diagnoses. Mycobacterial diseases, airway obstruction, and lung cancer are associated with silica dust exposure. As yet, no curative treatment exists, but comprehensive management strategies help to improve quality of life and slow deterioration. Further efforts are needed for recognition and control of silica hazards, especially in developing countries. Source


Chan K.C.A.,Chinese University of Hong Kong
Topics in Current Chemistry | Year: 2014

The presence of cell-free fetal DNA in the plasma of pregnant women has opened up the possibility of noninvasive prenatal diagnosis. With the advances in molecular techniques of microfluidics and massive parallel sequencing, an increasing number of fetal genetic diseases/conditions can be noninvasively detected using maternal plasma DNA analysis. Remarkably, it has recently been shown that the genome-wide genetic map of an unborn fetus can be constructed through extensive sequencing of maternal plasma DNA. In this chapter the different qualitative and quantitative approaches and related methodology for the analysis of fetal DNA in maternal plasma are discussed. © Springer-Verlag Berlin Heidelberg 2012. Source


Waye M.M.Y.,Chinese University of Hong Kong
Free Radical Research | Year: 2011

Obesity has become a worldwide epidemic that leads to many serious weight-related disorders. Recently, infection by viruses has been proposed as a possible cause of the obesity epidemic. Of the many viruses screened, adenovirus 36 has been found to be a strong candidate virus that is associated with obesity, based on evidence in various model systems as well as clinical data. The mechanism of how the adenovirus could lead to obesity is not known and this paper proposes some new insights into how oxidative stress could be a possible mechanism of how adenovirus might lead to obesity. This paper reviews the relevant literature of both the effect of adenovirus on cells' anti-oxidant response and the link between obesity and oxidative stress. © 2011 Informa UK, Ltd. Source


Wu R.,Chinese University of Hong Kong | Chen J.,CAS Institute of Atmospheric Physics | Chen W.,CAS Institute of Atmospheric Physics
Journal of Climate | Year: 2012

Observational analysis reveals three types of El Niño-Southern Oscillation (ENSO) influences on the Indian summer monsoon (ISM): indirect influence of the preceding winter [December-February (DJF)] eastern equatorial Pacific (EEP) sea surface temperature (SST) anomalies (DJF-only cases), direct influence of the concurrent summer [June-September (JJAS)] EEP SST anomalies (JJAS-only cases), and coherent influence of both the preceding winter and concurrent summer EEP SST anomalies (DJF&JJAS cases). The present study distinguishes the three types of ENSO influences and investigates the processes connecting ENSO to the ISM separately. In the DJF-only cases, the preceding winter EEP SST anomalies induce north Indian Ocean (NIO) SST anomalies through air-sea interaction processes in the tropical IndianOcean. The SSTanomalies over thewestern Indian Ocean alter the surface air humidity there. Both processes favor an anomalous ISM. In the JJAS-only cases, an anomalous ISM is directly induced by ENSO through large-scale circulation changes. The meridional thermal contrast may also contribute to an anomalous ISM. In the DJF&JJAS cases, the preceding winter EEP SST anomalies induce NIO SST anomalies and change the surface air humidity over the western Indian Ocean. Concurrent summer EEP SST anomalies induce large-scale vertical motion anomalies over South Asia. Together, they lead to an anomalous ISM. The anomalousmeridional thermal contrast may contribute to an anomalous ISM in late summer. Impacts of the preceding winter EEP SST anomalies in the DJF and JJAS cases may contribute to the contemporaneous correlation between ISM and EEP SST. There are more DJF&JJAS cases before than after the late 1970s. This provides an alternative interpretation for the observed weakening in the ISM-ENSO relationship around the late 1970s. © 2012 American Meteorological Society. Source


Wong W.S.,Chinese University of Hong Kong
IEEE Transactions on Information Theory | Year: 2011

Signal-to-noise (SNR) ratio is commonly regarded as a reliable performance measure for wireless communication systems. Knowledge of fundamental properties of the feasible SNR region can facilitate the performance optimization of multi-user wireless systems. This paper examines the concavity of the feasible SNR region. In particular, it is shown that for systems with only three users, the feasible SNR region is always concave. As concavity for 2-D systems is well known and concavity for 4-D systems does not hold in general, this result fills in a gap on this issue. A concavity result for systems with a general number of users is also established under certain technical conditions. © 2011 IEEE. Source


Wang C.C.L.,Chinese University of Hong Kong
IEEE Transactions on Visualization and Computer Graphics | Year: 2011

We present a new approach to compute the approximate Boolean operations of two freeform polygonal mesh solids efficiently with the help of Layered Depth Images (LDIs). After applying the LDI sampling-based membership classification, the most challenging part, a trimmed adaptive contouring algorithm, is developed to reconstruct the mesh surface from the LDI samples near the intersected regions and stitch it to the boundary of the retained surfaces. Our method of approximate Boolean operations holds the advantage of numerical robustness as the approach uses volumetric representation. However, unlike other methods based on volumetric representation, we do not damage the facets in nonintersected regions, thus preserving geometric details much better and speeding up the computation as well. We show that the proposed method can successfully compute the Boolean operations of free-form solids with a massive number of polygons in a few seconds. © 2011 IEEE. Source


Zhu F.,Chinese University of Hong Kong
Cochrane database of systematic reviews (Online) | Year: 2012

Fast-track cardiac care is a complex intervention involving several components of care during cardiac anaesthesia and in the postoperative period, all with the ultimate aim of early extubation after surgery, to reduce the length of stay in the intensive care unit and in the hospital. Safe and effective fast-track cardiac care may reduce hospital costs. This is an update of a Cochrane review published in 2003. To update the evidence on the safety and effectiveness of fast-track cardiac care compared to conventional (not fast-track) care in adult patients undergoing cardiac surgery. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 3), MEDLINE (January 1966 to April 2012), EMBASE (January 1980 to April 2012), CINAHL (January 1982 to April 2012), and ISI Web of Science (January 2003 to April 2012). We searched reference lists of articles and contacted experts in the field. All randomized controlled trials of adult cardiac surgical patients (coronary artery bypass grafts, aortic valve replacement, mitral valve replacement) that compared fast-track cardiac care and conventional (not fast-track) care groups were included. We focused on the following fast-track interventions that were designed for early extubation after surgery, administration of low-dose opioid based general anaesthesia during cardiac surgery and the use of a time-directed extubation protocol after surgery. The primary outcome was the risk of mortality. Secondary outcomes included postoperative complications, reintubation within 24 hours of surgery, time to extubation, length of stay in the intensive care unit and in the hospital, quality of life after surgery and hospital costs. Two review authors independently assessed trial quality and extracted the data. Study authors were contacted for additional information. We used a random-effects model and reported relative risk (RR), mean difference (MD) and 95% confidence intervals (95% CI). Twenty-five trials involving 4118 patients were included in the review. There were two studies with a low risk of bias and nine studies with a high risk of bias. There were no differences in the risk of mortality within the first year after surgery between low-dose versus high-dose opioid based general anaesthesia groups (RR 0.58, 95% CI 0.28 to 1.18) and between early extubation protocol versus usual care groups (RR 0.84, 95% CI 0.40 to 1.75).There were no significant differences between low-dose versus high-dose opioid based anaesthesia groups for postoperative complications: myocardial infarction (RR 0.98, 95% CI 0.48 to 1.99), reintubation (RR 1.77, 95% CI 0.38 to 8.27), acute renal failure (RR 1.19, 95% CI 0.33 to 4.33), major bleeding (RR 0.48, 95% CI 0.16 to 1.44), and stroke (RR 1.17, 95% CI 0.36 to 3.78). Compared to the usual care, there were no significant differences in the risk of postoperative complications associated with early extubation: myocardial infarction (RR 0.94, 95% CI 0.55 to 1.60), reintubation (RR 1.91, 95% CI 0.90 to 4.07), acute renal failure (RR 0.77, 95% CI 0.19 to 3.10), major bleeding (RR 0.80, 95% CI 0.45 to 1.44), stroke (RR 0.87, 95% CI 0.31 to 2.46), major sepsis (RR 1.25, 95% CI 0.08 to 19.75) and wound infection (RR 0.67, 95% CI 0.25 to 1.83).Although there were high levels of heterogeneity, both low-dose opioid anaesthesia and the use of time-directed extubation protocols were associated with reductions in the time to extubation (3.0 to 10.5 hours) and in the length of stay in the intensive care unit (0.4 to 8.7 hours). However, these fast-track care interventions were not associated with reductions in the total length of stay in hospital. One high quality cost-effectiveness analysis included in a randomized controlled trial showed that early extubation was likely to be cost-effective. The use of low-dose opioid based general anaesthesia and time-directed protocols for fast-track interventions have similar risks of mortality and major postoperative complications to conventional (not fast-track) care, and therefore appear to be safe in patients considered to be at low to moderate risk. These fast-track interventions reduced the time to extubation and shortened the length of stay in the intensive care unit, but did not reduce the length of stay in the hospital. Source


Li Y.Y.,Chinese University of Hong Kong
Mechanical Systems and Signal Processing | Year: 2010

Because of the sensitive characteristic to local defects, strain has been widely utilized to identify the presence, location, and severity of damage in structures, and this paper reviews recent publications regarding strain-related techniques on structural damage identification. A brief description on the strain-displacement relationship at defective areas is first presented. Then, damage identification using various strain-related parameters, such as strain (curvature) mode shape, strain energy, strain frequency response function, etc., is explored and the hypersensitivity of corresponding damage indicators will be examined systematically. Finally, some generalized criteria on the selection of strain-based parameters for damage identification are concluded and suggestions for future work are discussed. © 2009 Elsevier Ltd. All rights reserved. Source


Li L.,Chinese University of Hong Kong
Cochrane database of systematic reviews (Online) | Year: 2012

Threatened miscarriage occurs in 10% to 15% of all pregnancies. Vaginal spotting or bleeding during early gestation is common, with nearly half of those pregnancies resulting in pregnancy loss. To date, there is no effective preventive treatment for threatened miscarriage. Chinese herbal medicines have been widely used in Asian countries for centuries and have become a popular alternative to Western medicines in recent years. Many studies claim to show that they can prevent miscarriage. However, there has been no systematic evaluation of the effectiveness of Chinese herbal medicines for threatened miscarriage. To review the therapeutic effects of Chinese herbal medicines for the treatment of threatened miscarriage. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2012), Chinese Biomedical Database (1978 to 31 January 2012), China Journal Net (1915 to 31 January 2012), China National Knowledge Infrastructure (1915 to 31 January 2012), WanFang Database (1980 to 31 January 2012), Chinese Clinical Trial Registry (31 January 2012), EMBASE (1980 to 31 January 2012), CINAHL (31 January 2012), PubMed (1980 to 31 January 2012), Wiley InterScience (1966 to 31 January 2012), International Clinical Trials Registry Platform (31 January 2012) and reference lists of retrieved studies. We also contacted organisations, individual experts working in the field, and medicinal herb manufacturers. Randomised or quasi-randomised controlled trials that compared Chinese herbal medicines (alone or combined with other pharmaceuticals) with placebo, no treatment (including bed rest), or other pharmaceuticals as treatments for threatened miscarriage. Two review authors independently assessed all the studies for inclusion in the review, assessed risk of bias and extracted the data. Data were checked for accuracy. In total, we included 44 randomised clinical trials with 5100 participants in the review.We did not identify any trials which used placebo or no treatment (including bed rest) as a control.The rate of effectiveness (continuation of pregnancy after 28 weeks of gestation) was not significantly different between the Chinese herbal medicines alone group compared with the group of women receiving Western medicines alone (average risk ratio (RR) 1.23; 95% confidence interval (CI) 0.96 to 1.57; one trial, 60 women).Chinese herbal medicines combined with Western medicines were more effective than Western medicines alone to continue the pregnancy beyond 28 weeks of gestation (average RR 1.28; 95% CI 1.18 to 1.38; five trials, 550 women). There was insufficient evidence to assess the effectiveness of Chinese herbal medicines alone for treating threatened miscarriage.A combination of Chinese herbal and Western medicines was more effective than Western medicines alone for treating threatened miscarriage. However, the quality of the included studies was poor. More high quality studies are necessary to further evaluate the effectiveness of Chinese herbal medicines for threatened miscarriage. Source


Koh W.-J.,Sungkyunkwan University | Stout J.E.,Duke University | Yew W.-W.,Chinese University of Hong Kong
International Journal of Tuberculosis and Lung Disease | Year: 2014

Mycobacterium abscessus complex is a group of rapidly growing mycobacteria, and an emerging cause of nontuberculous mycobacterial lung disease in patients with cystic fibrosis and chronic lung diseases, such as bronchiectasis. M. abscessus complex is the most drugresistant of the mycobacterial pathogens, resulting in limited therapeutic options and a high treatment failure rate. M. abscessus complex is comprised of three closely related subspecies: M. abscessus (sensu stricto), M. massiliense and M. bolletii. M. abscessus encodes a functional erythromycin ribosomal methylase gene, erm(41), which modifies the binding site for macrolide antibiotics, causing inducible macrolide resistance. However, this inducible macrolide resistance is not seen in M. massiliense, as the erm(41) gene of this subspecies is non-functional. Accordingly, treatment success rates with macrolide-based antibiotic treatment are much higher in patients with M. massiliense infections than in those infected with M. abscessus. Precise speciation of M. abscessus complex is important for predicting antibiotic susceptibilities and patient outcome. © 2014 The Union. Source


Chan T.Y.K.,Chinese University of Hong Kong
Forensic Science International | Year: 2012

Detailed investigations of all reported cases of herb-induced aconite poisoning are necessary to identify the major contributory causes so that preventive measures can be formulated. In the present review of 12 fatal cases that were published in the medical journals during 1992 and 2011, the available clinical data and forensic toxicological analyses indicated that poor post-harvest processing of aconite roots, use of greater than the recommended doses and inadequate boiling of processed aconite roots during decoction preparation were important contributory factors in herb-induced aconite poisoning. Under such circumstances, the actual amount of Aconitum alkaloids ingested was much larger than intended. Good manufacturing practice to ensure adequate processing of aconite roots, use of the recommended doses, clear instructions for the patients and their compliance during decoction preparation are important preventive measures. © 2012 Elsevier Ireland Ltd. Source


Wei Y.,Catholic University of Louvain | Chen Y.,Chinese University of Hong Kong
International Journal of Production Economics | Year: 2011

An optimal joint operational and marketing decision is crucial for robust supply chain management. This paper addresses concurrent determination of inventory replenishment and sales effort decisions such as price, incentives to salesforce, and short-term promotions, or a combination of them. Market responses to sales efforts are typically highly uncertain, and demand in each period has its distribution dependent on the selected sales effort. In each period a replenishment order may be issued, which incurs both fixed and variable ordering costs, and at the same time the sales effort is also determined, the execution of which may incur costs. For such a model, the previously developed methods which are used for the joint inventory-pricing models become inadequate. A computational procedure for obtaining an optimal joint policy is addressed, and the conditions for the optimality of that policy are identified. © 2009 Elsevier B.V. All rights reserved. Source


Li F.,South China University of Technology | Du T.C.,Chinese University of Hong Kong
Decision Support Systems | Year: 2011

Online social blogs have gained popularity recently. They provide an effective channel for word-of-mouth (WoM) marketing to promote products or service. In WoM marketing, an opinion leader, who is normally more interconnected and has a higher social standing, can deliver product information, provide recommendations, give personal comments, and supplement professional knowledge that help companies to promote their products. Many theories have been put forward about social networks, but few address the issue of opinion leader identification. This study proposes a framework to identify opinion leaders using the information retrieved from blog content, authors, readers, and their relationships, which we call BARR for short. We first build ontology for a marketing product and then collect parameters from BARR to identify "hot topics" related to the product. These hot topics are then associated with information disseminators, or opinion leaders. Marketers can use BARR to track blogs written by opinion leaders and identify their opinions to form effective marketing strategies. © 2010 Elsevier B.V. All rights reserved. Source


Barkun A.N.,McGill University | Bardou M.,French Institute of Health and Medical Research | Kuipers E.J.,Erasmus Medical Center | Sung J.,Chinese University of Hong Kong | And 3 more authors.
Annals of Internal Medicine | Year: 2010

Description: A multidisciplinary group of 34 experts from 15 countries developed this update and expansion of the recommendations on the management of acute nonvariceal upper gastrointestinal bleeding (UGIB) from 2003. Methods: The Appraisal of Guidelines for Research and Evaluation (AGREE) process and independent ethics protocols were used. Sources of data included original and published systematic reviews; randomized, controlled trials; and abstracts up to October 2008. Quality of evidence and strength of recommendations have been rated by using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. Recommendations: Recommendations emphasize early risk stratification, by using validated prognostic scales, and early endoscopy (within 24 hours). Endoscopic hemostasis remains indicated for high-risk lesions, whereas data support attempts to dislodge clots with hemostatic, pharmacologic, or combination treatment of the underlying stigmata. Clips or thermocoagulation, alone or with epinephrine injection, are effective methods; epinephrine injection alone is not recommended. Second-look endoscopy may be useful in selected high-risk patients but is not routinely recommended. Preendoscopy proton-pump inhibitor (PPI) therapy may downstage the lesion; intravenous high-dose PPI therapy after successful endoscopic hemostasis decreases both rebleeding and mortality in patients with high-risk stigmata. Although selected patients can be discharged promptly after endoscopy, high-risk patients should be hospitalized for at least 72 hours after endoscopic hemostasis. For patients with UGIB who require a nonsteroidal anti-inflammatory drug, a PPI with a cyclooxygenase-2 inhibitor is preferred to reduce rebleeding. Patients with UGIB who require secondary cardiovascular prophylaxis should start receiving acetylsalicylic acid (ASA) again as soon as cardiovascular risks outweigh gastrointestinal risks (usually within 7 days); ASA plus PPI therapy is preferred over clopidogrel alone to reduce rebleeding. © 2010 American College of Physicians. Source


One paper in a preceding issue of this journal has introduced the Bayesian Ying-Yang (BYY) harmony learning from a perspective of problem solving, parameter learning, and model selection. In a complementary role, the paper provides further insights from another perspective that a co-dimensional matrix pair (shortly co-dim matrix pair) forms a building unit and a hierarchy of such building units sets up the BYY system. The BYY harmony learning is re-examined via exploring the nature of a co-dim matrix pair, which leads to improved learning performance with refined model selection criteria and a modified mechanism that coordinates automatic model selection and sparse learning. Besides updating typical algorithms of factor analysis (FA), binary FA (BFA), binary matrix factorization (BMF), and nonnegative matrix factorization (NMF) to share such a mechanism, we are also led to (a) a new parametrization that embeds a de-noise nature to Gaussian mixture and local FA (LFA); (b) an alternative formulation of graph Laplacian based linear manifold learning; (c) a codecomposition of data and covariance for learning regularization and data integration; and (d) a co-dim matrix pair based generalization of temporal FA and state space model. Moreover, with help of a co-dim matrix pair in Hadamard product, we are led to a semi-supervised formation for regression analysis and a semi-blind learning formation for temporal FA and state space model. Furthermore, we address that these advances provide with new tools for network biology studies, including learning transcriptional regulatory, Protein-Protein Interaction network alignment, and network integration. © 2011 Higher Education Press and Springer-Verlag Berlin Heidelberg. Source


Liu R.-B.,Chinese University of Hong Kong | Yao W.,University of Hong Kong | Sham L.J.,University of California at San Diego
Advances in Physics | Year: 2010

We review the progress and main challenges in implementing large-scale quantum computing by optical control of electron spins in quantum dots (QDs). Relevant systems include self-assembled QDs of III-V or II-VI compound semiconductors (such as InGaAs and CdSe), monolayer fluctuation QDs in compound semiconductor quantum wells, and impurity centres in solids, such as P-donors in silicon and nitrogen-vacancy centres in diamond. The decoherence of the electron spin qubits is discussed and various schemes for countering the decoherence problem are reviewed. We put forward designs of local nodes consisting of a few qubits which can be individually addressed and controlled. Remotely separated local nodes are connected by photonic structures (microcavities and waveguides) to form a large-scale distributed quantum system or a quantum network. The operation of the quantum network consists of optical control of a single electron spin, coupling of two spins in a local nodes, optically controlled quantum interfacing between stationary spin qubits in QDs and flying photon qubits in waveguides, rapid initialization of spin qubits and qubit-specific single-shot non-demolition quantum measurement. The rapid qubit initialization may be realized by selectively enhancing certain entropy dumping channels via phonon or photon baths. The single-shot quantum measurement may be in situ implemented through the integrated photonic network. The relevance of quantum non-demolition measurement to large-scale quantum computation is discussed. To illustrate the feasibility and demand, the resources are estimated for the benchmark problem of factorizing 15 with Shor's algorithm. © 2010 Taylor & Francis. Source


Ching J.Y.L.,Chinese University of Hong Kong
American Journal of Gastroenterology | Year: 2016

Objectives:We tested the hypothesis that the risk of colorectal cancer (CRC), advanced colorectal neoplasia (ACN), and colorectal adenoma among screening participants with different first-degree relatives (FDRs) affected by CRC was similar.Methods:A multi-center, prospective colonoscopy study involving 16 Asia-Pacific regions was performed from 2008 to 2015. Consecutive self-referred CRC screening participants aged 40–70 years were recruited, and each subject received one direct optical colonoscopy. The prevalence of CRC, ACN, and colorectal adenoma was compared among subjects with different FDRs affected using Pearson’s χ2 tests. Binary logistic regression analyses were performed to evaluate the risk of these lesions, controlling for recognized risk factors including age, gender, smoking habits, alcohol drinking, body mass index, and the presence of diabetes mellitus.Results:Among 11,797 asymptomatic subjects, the prevalence of CRC was 0.6% (none: 0.6%; siblings: 1.1%; mother: 0.5%; father: 1.2%; ≥2 members: 3.1%, P<0.001), that of ACN was 6.5% (none: 6.1%; siblings: 8.3%; mother: 7.7%; father: 8.7%; ≥2 members: 9.3%, P<0.001), and that of colorectal adenoma was 29.3% (none: 28.6%; siblings: 33.5%; mother: 31.8%; father: 31.1%; ≥2 members: 38.1%, P<0.001). In multivariate regression analyses, subjects with at least one FDR affected were significantly more likely to have CRC (adjusted odds ratio (AOR)=2.02–7.89), ACN (AOR=1.55–2.06), and colorectal adenoma (AOR=1.31–1.92) than those without a family history. The risk of CRC (AOR=0.90, 95% confidence interval (CI) 0.34–2.35, P=0.830), ACN (AOR=1.07, 95% CI 0.75–1.52, P=0.714), and colorectal adenoma (AOR=0.96, 95% CI 0.78–1.19, P=0.718) in subjects with either parent affected was similar to that of subjects with their siblings affected.Conclusions:The risk of colorectal neoplasia was similar among subjects with different FDRs affected. These findings do not support the need to discriminate proband identity in screening participants with affected FDRs when their risks of colorectal neoplasia were estimated.Am J Gastroenterol advance online publication, 15 March 2016; doi:10.1038/ajg.2016.52. © 2016 American College of Gastroenterology Source


Lu H.J.,Chinese University of Hong Kong
Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior | Year: 2012

Because women's faces and bodies carry different cues of reproductive value, men may attend to different perceptual cues as functions of their long-term versus short-term mating motivations. We tested this hypothesis in three experiments on 135 male and 132 female participants. When influenced by short-term rather than long-term mating motivations, men's attention was captured by (Study 1), was shifted to (Study 2), and was distracted by (Study 3) the waist/hip area rather than the face on photographs of attractive women. Similar effects were not found among the female participants in response to photographs of attractive men. These results support the evolutionary view that, similar to the attentional selectivity found in other domains of life, male perceptual attention has evolved to selectively capture and hold reproductive information about the opposite sex as a function of short-term versus long-term mating goals. Source


Hui D.S.,Chinese University of Hong Kong | Zumla A.,University College London
Current Opinion in Pulmonary Medicine | Year: 2015

Purpose of review This article reviews the clinical and treatment aspects of avian influenza viruses and the Middle East Respiratory Syndrome coronavirus (MERS-CoV). Recent findings Avian influenza A(H5N1) and A(H7N9) viruses have continued to circulate widely in some poultry populations and infect humans sporadically. Sporadic human cases of avian A(H5N6), A(H10N8) and A(H6N1) have also emerged. Closure of live poultry markets in China has reduced the risk of A(H7N9) infection. Observational studies have shown that oseltamivir treatment for adults hospitalized with severe influenza is associated with lower mortality and better clinical outcomes, even as late as 4-5 days after symptom onset. Whether higher than standard doses of neuraminidase inhibitor would provide greater antiviral effects in such patients requires further investigation. High-dose systemic corticosteroids were associated with worse outcomes in patients with A(H1N1)pdm09 or A(H5N1). MERS-CoV has continued to spread since its first discovery in 2012. The mortality rates are high in those with comorbid diseases. There is no specific antiviral treatment or vaccine available. The exact mode of transmission from animals to humans remains unknown. Summary There is an urgent need for developing more effective antiviral therapies to reduce morbidity and mortality of these emerging viral respiratory tract infections. © 2015 Wolters Kluwer Health, Inc. All rights reserved. Source