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National Taiwan University is a national co-educational research university located in Taipei, Taiwan. Its 1,086,167 m2 main campus is located in Taipei's Da'an District. In addition, the university has 6 other campuses in Taipei and elsewhere, with a total area of 345,830,000 m2. The University consists of 11 colleges, 54 departments, 103 graduate institutes and 4 research centers. In 2010, the student body consisted of 17,514 undergraduate students and 15,824 graduate students.The university was founded in 1928 by the Japanese administration during the Japanese colonial era and was then known as the Taihoku Imperial University. After World War II, the government of the Republic of China resumed the administration of Taihoku University and reorganized and renamed it National Taiwan University on November 15, 1945.NTU is often considered to be one of the most prestigious universities in Taiwan. It also has strong ties with the Academia Sinica in Taiwan. Wikipedia.

Okuyama T.,National Taiwan University
Journal of Animal Ecology | Year: 2012

1.The functional response of predators describes the rate at which a predator consumes prey and is an important determinant of community dynamics. Despite the importance, most empirical studies have considered a limited number of models of functional response. In addition, the models often make strong assumptions about the pattern of predation processes, even though functional responses can potentially exhibit a wide variety of patterns. 2.In addition to the limited model consideration, model selections of functional response models cannot tease apart the components of predation (i.e. capture rate and handling time) when flexible traits are considered because it is always possible that many different combinations of the capture rate and handling time can lead to the same predation rate. 3.This study directly examined the capture rate and handling time of functional response in a mite community. To avoid the model selection problem, the searching and handling behaviour data were collected. The model selection was applied directly to these two components of predation data. Commonly used functional response models and models that allow for more flexible patterns were compared. 4.The results indicated that assumptions of the commonly used models were not supported by the data, and a flexible model was selected as the best model. These results suggest the need to consider a wider variety of predation patterns when characterizing a functional response. Without making a strong assumption (e.g. static handling time), model selections on functional response models cannot be used to make reliable inferences on the predation mechanisms. © 2011 The Author. Journal of Animal Ecology © 2011 British Ecological Society.

Liu C.-H.,National Taiwan University
Expert Systems with Applications | Year: 2011

Social network bridging is central to diffusion of information and knowledge. It is also a key mechanism through which social network structure affects individuals. Bridging can be contrasted with triadic closure and all of the social capital benefits. But this research found that structural holes benefit unable to appear when network structure is not close enough. With cluster analysis, this research also finds that photoelectric industries present close interaction in innovation activities than other industries in Taiwan, thereby obtaining competitive advantage in the world. © 2010 Elsevier Ltd. All rights reserved.

Jang S.,Queens College, City University of New York | Cheng Y.-C.,National Taiwan University
Wiley Interdisciplinary Reviews: Computational Molecular Science | Year: 2013

Recent experimental and theoretical studies suggest that biological photosynthetic complexes utilize the quantum coherence in a positive manner for efficient and robust flow of electronic excitation energy. Clear and quantitative understanding of such suggestion is important for identifying the design principles behind efficient flow of excitons coherently delocalized over multiple chromophores in condensed environments. Adaptation of such principles for synthetic macromolecular systems has also significant implication for the development of novel photovoltaic systems. Advanced theories of resonance energy transfer are presented, which can address these issues. Applications to photosynthetic light harvesting complex systems and organic materials demonstrate the capabilities of new theoretical approaches and future challenges. © 2012 John Wiley & Sons, Ltd.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Diabetes Care | Year: 2012

OBJECTIVE - The association between pioglitazone and bladder cancer has not been investigated in Asians. We aimed to investigate this association. RESEARCH DESIGN AND METHODS - A total of 1,000,000 individuals were randomly sampled from the National Health Insurance database, and incident cases of bladder cancer during the period from 1 January 2006 to 31 December 2009 were analyzed among 54,928 patients with type 2 diabetes and without previous bladder cancer. RESULTS - Among 165 incident case subjects, 10 (0.39%) were ever users and 155 (0.30%) were never users of pioglitazone (adjusted hazard ratio in full model 1.305 [95% CI 0.661-2.576]). All bladder cancer in ever users occurred within a duration of therapy <24 months, suggesting an early effect of pioglitazone on bladder cancer or late use of pioglitazone in high-risk patients. CONCLUSIONS - The association between pioglitazone and bladder cancer was not significant. However, confirmation of this finding is required because of the possible lack of statistical power owing to the small number of events. © 2012 by the American Diabetes Association.

Lee C.-K.,Academia Sinica, Taiwan | Pao C.-W.,Academia Sinica, Taiwan | Chen C.-W.,National Taiwan University
Energy and Environmental Science | Year: 2013

A comprehensive insight into the correlations of the nanoscale organizations of polymer and nanocrystals in polymer/inorganic nanocrystal bulk heterojunction (BHJ) hybrid solar cells is the key toward nanomorphology control for improving device performance. In this study, we investigated the organizations of both the polymer and nanocrystals in polymer/inorganic nanocrystal hybrid solar cells by performing multiscale molecular simulations of P3HT:TiO2 nanocrystal BHJs incorporating nanocrystals with two different dimensionalities, namely, zero-dimensional nanoparticles (NPs), and one-dimensional nanorods (NRs). We reveal that nanocrystal dimensionality has significant impacts on the polymer/nanocrystal organizations for polymer/inorganic nanocrystal hybrid blends. One-dimensional nanocrystals, such as TiO2 NRs, can effectively enhance the polymer degree of crystallinity as a result of preferential polymer chain alignment along the axial dimension of the NRs, thereby promoting hole transport; in addition, the elongated, anisotropic NRs significantly reduce the probability of electron hopping, and maintain a high specific interfacial area for efficient exciton dissociation. Therefore, the present study demonstrates the possibility of the nanoscale morphology control of polymer/inorganic nanocrystal BHJ hybrid blends via tuning the nanocrystal shapes, which is potentially helpful for developing next-generation polymer/inorganic nanocrystal hybrid electronic devices such as solar cells or thin film transistors. © The Royal Society of Chemistry 2013.

Liu C.-S.,National Taiwan University
Inverse Problems in Science and Engineering | Year: 2015

In the iterative solution of an ill-posed linear system (Formula presented.) , how to select a fast and easily established descent direction (Formula presented.) to reduce the residual (Formula presented.) is an important issue. A mathematical procedure to find a double optimal descent direction (Formula presented.) in (Formula presented.) , without inverting (Formula presented.) , is developed in an (Formula presented.) -dimensional Krylov subspace. The novelty is that we expand (Formula presented.) in an affine Krylov subspace with undetermined coefficients, and then two optimization techniques are used to determine these coefficients in closed form, which can greatly accelerate the convergence speed in solving the ill-posed linear problems. The double optimal descent algorithm is proven to be absolutely convergent very fast, accurate and robust against noise, which is confirmed by numerical tests of several linear inverse problems, including the heat source identification problem, the backward heat conduction problem, the inverse Cauchy problem and the external force identification problem. © 2014 Taylor & Francis.

Chou K.T.,National Taiwan University
Energy Policy | Year: 2013

This study attempts to explore the risk perceptions of climate change in Taiwan. It probes into the public's views toward governments' risk communication regarding climate change, citizens' participation in decision-making, and their trust in the capacity of governments toward risk governance, as well as their attitude towards corporate social responsibility. For analysis, we developed ten types of perceptions under three dimensions: namely the severity of climate change (Type 1), the development of sustainable society (Types 2, 3, 4 and 5), and the risk governance and communication (Types 6, 7, 8, 9 and 10) to discuss whether the Taiwanese public's perception of climate change was prepared for a socially reflective paradigm shift. Regarding the three dimensions in the questionnaire design, although this study individually measured the public's risk perception, there was a high correlation between the variance analysis results among the three dimensions. This could systematically explain the potential change of the governance paradigm in Taiwanese society concerning structural transformation. © 2013 Elsevier Ltd.

Huang M.-H.,National Taiwan University
Online Information Review | Year: 2012

Purpose - The purpose of this study is to evaluate the scientific performance of universities by extending the application of the h-index from the individual to the institutional level. A ranking of the world's top universities based on their h-index scores was produced. The geographic distribution of the highly ranked universities by continent and by country was also analysed. Design/approach/methodology - This study uses bibliometric analysis to rank the universities. In order to calculate their h-index the numbers of papers and citations in each university were gathered from Web of Science, including the Science Citation Index and Social Science Citation Index. Authority control dealing with variations in university names ensured the accuracy of each university's number of published journal papers and the subsequent statistics of their citations. Findings - It was found that a high correlation exists between the h-index ranking generated in this study and that produced by Shanghai Jiao Tong University. The results confirm the validity of the h-index in the assessment of research performance at the university level. Originality/value - The h-index has been used to evaluate research performance at the institutional level in several recent studies; however these studies evaluated institutions' performance only in certain disciplines or in a single country. This paper measures the research performance of universities all over the world, and the applicability of the h-index at the institutional level was validated by calculating the correlation between the ranking result of the h-index and the ranking by the Shanghai Jiao Tong University. Copyright © 2012 Emerald Group Publishing Limited. All rights reserved.

Chen C.-Y.,National Taiwan University
Journal of Clinical Gerontology and Geriatrics | Year: 2010

Some of the above eldercare problems are unique to Taiwan, while some are common issues confronting Taiwan, her Asian neighbors and other countries. All, however, are serious challenges that must be successfully overcome for the sustainable development of geriatric care and gerontology.9 In Taiwan, a recent restructure of the Executive Yuan will lead to the establishment of an independent Ministry of Health and Welfare in 2012. The new government agency will have the crucial mission of tackling the problems generated by rapid population aging in Taiwan, especially with regard to critical issues related to eldercare, notably comorbidities, geriatric syndromes, over-specialization, and polypharmacy. Eldercare in the future is bound to rely to a great extent on professional geriatric teams composed of specialists from a wide spectrum of disciplines. However, the required manpower in Taiwan is lacking as training for geriatricians and allied medical specialists is still in the nascent stage. Lack of active participation from physicians in the long-term care system in particular has been a pressing problem that is potentially harmful to the smooth transition from medical care to daily life care for elderly people. Geriatricians and gerontologists should assume a more vigorous role in addressing the issues of disability prevention in eldercare and developing workable interventions against disabilities to assist inmaking the to-be-implemented long-term care insurance program more effective. According to the 2020 Health White Paper published by the Department of Health in 2008, active aging is upheld as the vision for eldercare in Taiwan, and various strategies have been proposed to achieve the vision from the three aspects of "quality medical care", "healthy lifestyle", and "supportive social environment". In the white paper that incorporates the elderly as a focus group, five indicators have been set up and applied to assess policy effectiveness in meeting the needs of Taiwan's elderly people grouped according to their health status. With the aim of promoting active aging and disability prevention, the five quantitative indicators concentrate on: (1) the prevention of frailty and geriatric syndromes; (2) the prevention of falls; (3) the promotion of geriatric rehabilitation and stroke disability prevention; (4) depression screening and suicide prevention; and (5) promotion of advance directives.10 In response to the above challenges of an aging society in Taiwan, we need to conduct more research, learn from the eldercare experiences of advanced countries, and expedite active international exchange and collaboration so as to provide the government with solid and effective advice in the development of Taiwan's eldercare policies. © 2010, Asia Pacific League of Clinical Gerontology and Geriatrics. Published by Elsevier Taiwan LLC. All rights reserved.

Huang C.-F.,Oregon Health And Science University | Huang C.-F.,National Taiwan University | Banker G.,Oregon Health And Science University
Traffic | Year: 2012

Polarized kinesin-driven transport is crucial for development and maintenance of neuronal polarity. Kinesins are thought to recognize biochemical differences between axonal and dendritic microtubules in order to deliver their cargoes to the appropriate domain. To identify kinesins that mediate polarized transport, we prepared constitutively active versions of all the kinesins implicated in vesicle transport and expressed them in cultured hippocampal neurons. Seven kinesins translocated preferentially to axons and five translocated into both axons and dendrites. None translocated selectively to dendrites. Highly homologous members of the same subfamily displayed distinctly different translocation preferences and were differentially regulated during development. By expressing chimeric kinesins, we identified two microtubule-binding elements within the motor domain that are important for selective translocation. We also discovered elements in the dimerization domain of kinesin-2 motors that contribute to their selective translocation. These observations indicate that selective interactions between kinesin motor domains and microtubules can account for polarized transport to the axon, but not for selective dendritic transport. © 2011 John Wiley & Sons A/S.

Wu K.C.-C.,National Taiwan University
Behavioral and Brain Sciences | Year: 2011

Based on their drugs as instruments framework, Müller & Schumann (M&S) propose a staged drug policy that matches well the neoliberal governance scheme. To mend the sad loss of the sociocultural dimension in their model, I propose three such considerations: first, sociocultural interactions with the brain; second, sociocultural context and justice of drug use; and third, sociocultural preparedness for implementing their drug policy. © 2011 Cambridge University Press.

The number of elderly and the prevalence of dementia have grown considerably in recent years. Little is known about how aging and dementia affect care patterns after discharge for acute coronary syndrome (ACS). This study was designed to assess the impact of dementia on care patterns after admission for patients with ACS across different age groups. Of 87,321 patients hospitalized for ACS between 1 January 2006 and 31 December 2007, 1,835 patients with dementia and 3,670 matched patients without dementia (1:2 ratio, matched by age, sex and hospital level) were identified from Taiwan's National Health Insurance Research Database. Use of interventional therapies at hospitalization and guideline-recommended medications post-discharge were compared between patients with and without dementia across different age groups (≤65, 66-75, 76-85, ≥86 years). Multivariate logistic regression models were performed to examine the impact of dementia on care patterns. Overall, dementia was associated with a 27% lower likelihood of receipt of interventional therapies [adjusted odds ratio (OR) = 0.73; 95% CI 0.63, 0.83] and a 22% lower likelihood of guideline-recommended medications (adjusted OR = 0.78; 95% CI 0.68, 0.89) in ACS patients. The use of interventional therapies and guideline-recommended medications decreased with age, and interactions between age and dementia were found. The proportions of patients receiving interventional therapies were 39.4% (without dementia) versus 21.8% (with dementia) in the youngest age group and 18.6% (without dementia) versus 14.5% (with dementia) in the oldest age group. Patients with dementia (age ≤65 years 73.6%; age 66-75 years 82.3%; age 76-85 years 71.8%; age ≥86 years 55.6%) were less likely to receive guideline-recommended medications as compared with those without dementia (age ≤65 years 85.6%; age 66-75 years 87.5%; age 76-85 years 81.2%; age ≥86 years 62.0%). Dementia and aging were associated with decreased use of interventional therapies and guideline-recommended medications in ACS patients.

Ho J.-K.,Center for Theoretical science | Ho J.-K.,Brown University | Ma C.-T.,National Taiwan University
Nuclear Physics B | Year: 2015

We study the generalized Dirac-Born-Infeld (DBI) action, which describes a q-brane ending on a p-brane with a (q+. 1)-form background. This action has the equivalent descriptions in commutative and non-commutative settings, which can be shown from the generalized metric and Nambu-Sigma model. We mainly discuss the dimensional reduction of the generalized DBI at the massless level on the flat spacetime and constant antisymmetric background in the case of flat spacetime, constant antisymmetric background and the gauge potential vanishes for all time-like components. In the case of q = 2, we can do the dimensional reduction to get the DBI theory. We also try to extend this theory by including a one-form gauge potential. © 2015 The Authors.

Ma C.-T.,National Taiwan University
Nuclear Physics B | Year: 2015

Double sigma model with strong constraints is equivalent to the ordinary sigma model by imposing a self-duality relation. The gauge symmetries are the diffeomorphism and one-form gauge transformation with the strong constraints. We consider boundary conditions in the double sigma model from three ways. The first way is to modify the Dirichlet and Neumann boundary conditions with a fully O(D, D) description from double gauge fields. We perform the one-loop β function for the constant background fields to find low-energy effective theory without using the strong constraints. The low-energy theory can also have O(D, D) invariance as the double sigma model. The second way is to construct different boundary conditions from the projectors. The third way is to combine the antisymmetric background field with field strength to redefine an O(D, D) generalized metric. We use this generalized metric to reconstruct a consistent double sigma model with the classical and quantum equivalence. © 2015 The Author.

Dai A.,National Taiwan University
Physics of Fluids | Year: 2015

Gravity currents generated from an instantaneous buoyancy source propagating down a slope in the range of 0° ≤ θ < 90° have been investigated in the acceleration phase by means of high-resolution two-dimensional simulations of the incompressible Navier-Stokes equations with the Boussinesq approximation. Front velocity history shows that, after the heavy fluid is released from rest, the flow goes through the acceleration phase, reaching a maximum front velocity Uf, max, and followed by the deceleration phase. The existence of a maximum of Uf, max is found near θ = 40°, which is supported by the improved theory. It is identified for the first time that the time of acceleration decreases as the slope angle increases, when the slope angle is approximately greater than 10°, and the time of acceleration increases as the slope angle increases for gravity currents on lower slope angles. A fundamental difference in flow patterns, which helps explain the distinct characteristics of gravity currents on high and low slope angles using scaling arguments, is revealed. Energy budgets further show that, as the slope angle increases, the ambient fluid is more easily engaged in the gravitational convection and the potential energy loss is more efficiently converted into the kinetic energy associated with ambient fluid. The propagation of gravity currents on a slope is found to be qualitatively modified as the depth ratio, i.e., the lock height to channel height ratio, approaches unity. As the depth ratio increases, the conversion of potential energy loss into the kinetic energy associated with heavy fluid is inhibited and the conversion into the kinetic energy associated with ambient fluid is enhanced by the confinement of the top wall. © 2015 AIP Publishing LLC.

Chen P.,National Taiwan University
Journal of Mathematical Imaging and Vision | Year: 2011

We present a novel multiple-linked iterative closest point method to estimate correspondences and the rigid/non-rigid transformations between point-sets or shapes. The estimation task is carried out by maximizing a symmetric similarity function, which is the product of the square roots of correspondences and a kernel correlation. The local mean square error analysis and robustness analysis are provided to show our method's superior performance to the kernel correlation method. © Springer Science+Business Media, LLC 2010.

Shyu S.J.,Ming Chuan University | Chen K.,National Taiwan University
Information Sciences | Year: 2011

The secret sharing schemes in conventional visual cryptography are capable of sharing one secret image into a set of random transparencies (called shares) in the form of rectangles, which reveal the secret image to the human visual system when they are superimposed. Recently, visual secret sharing schemes involving multiple secrets have attracted much attention. By adopting rotations on one of the two encoded circle shares, more than two secrets could be shared. Yet, the encoding and decoding processes of circle shares need more sophisticated mechanisms than those of rectangular or square ones. In this paper, we explore the possibilities of visual multiple secret sharing using simply two rectangular or square shares. Specifically, we define some operations onto a transparency based upon turning over or flipping around. Then we propose visual cryptographic schemes that are able to encode two or four secrets into two rectangular shares and up to eight secrets into two square shares such that the secrets cannot be obtained from any single share, whereas they are revealed by stacking the two shares under various combinations of turning or flipping operations. The proposed schemes, which solidly elaborate the relationship between the encoded shares and the shared secrets, broaden the research scope and enrich the flexibility and applicability of visual cryptography or image encryption theoretically and practically. © 2011 Elsevier Inc. All rights reserved.

Liu C.-S.,National Taiwan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2010

We propose a novel technique, transforming the generalized Sturm-Liouville problem: w"+q(x;a;)w = 0, a 1(a;)w(0)+a 2(a;)w'(1) = 0, b 1(a;)w(1)+ b 2(a;)w'(1) = 0 into a canonical one: y" = f, y(0) = y(1) = c(a;). Then we can construct a very effective Lie-group shooting method (LGSM) to compute eigenvalues and eigenfunctions, since both the left-boundary conditions y(0) = c(a;) and y'(0)=A(a;) can be expressed explicitly in terms of the eigen-parameter a;. Hence, the eigenvalues and eigenfunctions can be easily calculated with better accuracy, by a finer adjusting of a; to match the right-boundary condition y(1) = c(a;). Numerical examples are examined to show that the LGSM possesses a significantly improved performance. When comparing with exact solutions, we find that the LGSM can has accuracy up to the order of 10 -10. © 2010 Tech Science Press.

Liu C.-S.,National Taiwan University
Inverse Problems in Science and Engineering | Year: 2013

A future cone in the Minkowski space, defined in terms of the square-norm of the residual vector for an ill-posed linear system to be solved, is used to derive an optimal tri-vector descent system of nonlinear ordinary differential equations (ODEs). Then, a simple Euler scheme is used to generate an iterative algorithm from these ODEs, of which the two parameters appeared are optimized from a properly defined merit function to accelerate the convergence speed in solving the ill-posed linear systems. The optimal tri-vector iterative algorithm (OTVIA) is fast convergent and accurate, which is proven by numerical tests of inverse problems, including the backward heat conduction problem, the Calderón inverse problem and the inverse Cauchy problems. By defining a suitable convergence rate, we assess the convergence speeds of OTVIA and the conjugate gradient method (CGM), which reveal that the performance of OTVIA is better than the CGM. Also by comparing the OTVIA with the generalized minimal residual method (GMRES), we observe that the OTVIA is better than the GMRES. © 2013 Copyright Taylor and Francis Group, LLC.

Hirano N.,National Taiwan University | Liu F.-C.,Max Planck Institute for Radio Astronomy
Astrophysical Journal | Year: 2014

Two submillimeter/millimeter sources in the Barnard 1b (B1-b) core, B1-bN and B1-bS, have been studied in dust continuum, H13CO+ J = 1-0, CO J = 2-1, 13CO J = 2-1, and C18O J = 2-1. The spectral energy distributions of these sources from the mid-IR to 7 mm are characterized by very cold temperatures of T dust < 20 K and low bolometric luminosities of 0.15-0.31 L ⊙. The internal luminosities of B1-bN and B1-bS are estimated to be <0.01-0.03 L ⊙ and 0.1-0.2 L ⊙, respectively. Millimeter interferometric observations have shown that these sources have already formed central compact objects of 100 AU sizes. Both B1-bN and B1-bS are driving the CO outflows with low characteristic velocities of 2-4 km s-1. The fractional abundance of H13CO+ at the positions of B1-bN and B1-bS is lower than the canonical value by a factor of four to eight. This implies that a significant fraction of CO is depleted onto dust grains in the dense gas surrounding these sources. The observed physical and chemical properties suggest that B1-bN and B1-bS are in an earlier evolutionary stage than most of the known class 0 protostars. In particular, the properties of B1-bN agree with those of the first hydrostatic core predicted by the MHD simulations. The CO outflow was also detected in the mid-IR source located at 15″ from B1-bS. Since the dust continuum emission was not detected in this source, the circumstellar material surrounding this source is less than 0.01 M ⊙. It is likely that the envelope of this source was dissipated by the outflow from the protostar that is located to the southwest of B1-b. © 2014. The American Astronomical Society. All rights reserved.

Liu C.-S.,National Taiwan University
Computers, Materials and Continua | Year: 2011

For the computational applications in several areas, we propose a singlescale and a multi-scale diagonal preconditioners to reduce the condition number of Vandermonde matrix. Then a new algorithm is given to solve the inversion of the resulting coefficient matrix after multiplying by a preconditioner to the Vandermonde matrix. We apply the new techniques to the interpolation of data by using very high-order polynomials, where the Runge phenomenon disappears even the equidistant nodes are used. In addition, we derive a new technique by employing an m-order polynomial with a multi-scale technique to interpolate 2m+1 data. Numerical results confirm the validity of present polynomial interpolation method, where only a constant parameter R0 needs to be specified in the multi-scale expansion. For the Differential Quadrature (DQ), the present method provides a very accurate numerical differential. Then, by a combination of this DQ and the Fictitious Time Integration Method (FTIM), we can solve nonlinear boundary value problems effectively.

Liu C.-S.,National Taiwan University
Computers, Materials and Continua | Year: 2013

An optimal m-vector descent iterative algorithm in a Krylov subspace is developed, of which the m weighting parameters are optimized from a properly defined objective function to accelerate the convergence rate in solving an ill-posed linear problem. The optimal multi-vector iterative algorithm (OMVIA) is convergent fast and accurate, which is verified by numerical tests of several linear inverse problems, including the backward heat conduction problem, the heat source identification problem, the inverse Cauchy problem, and the external force recovery problem. Because the OMVIA has a good filtering effect, the numerical results recovered are quite smooth with small error, even under a large noise up to 10%. Copyright © 2013 Tech Science Press.

The paper aims to develop a novel pitch control system for a large wind turbine driven by a variable-speed pump-controlled hydraulic servo system. To perform practical pitch control experiments, a full-scale test rig of the hydraulic pitch control system for a 2 MW wind turbine's blade, including a novel pitch control mechanism, a variable-speed pump-controlled hydraulic servo system, a disturbance system and a PC-based control system, is designed and set up. The variable-speed pump-controlled hydraulic servo system, containing an AC servo motor, a constant displacement hydraulic piston pump two differential hydraulic cylinders and hydraulic circuits, achieved high response and high energy efficiency, so it is suitable for wind turbine applications. Besides, to implement the pitch control in the proposed novel pitch control system, an adaptive fuzzy controller with self-tuning fuzzy sliding-mode compensation (AFC-STFSMC) is developed to design the pitch controller. Finally, the developed variable-speed pump-controlled hydraulic servo system was built and verified for the path tracking control and path-positioning control of the pitch control of the wind turbines by practical experiments in a full-scale test rig under different path profiles, load torques, and random wind speeds. © 2010 Elsevier Ltd. All rights reserved.

Wang Y.-T.,Providence University | Lee A.J.T.,National Taiwan University
Expert Systems with Applications | Year: 2011

Understanding the navigational behaviour of website visitors is a significant factor of success in the emerging business models of electronic commerce and even mobile commerce. However, Web traversal patterns obtained by traditional Web usage mining approaches are ineffective for the content management of websites. They do not provide the big picture of the intentions of the visitors. The Web navigation patterns, termed throughout-surfing patterns (TSPs) as defined in this paper, are a superset of Web traversal patterns that effectively display the trends toward the next visited Web pages in a browsing session. TSPs are more expressive for understanding the purposes of website visitors. In this paper, we first introduce the concept of throughout-surfing patterns and then present an efficient method for mining the patterns. We propose a compact graph structure, termed a path traversal graph, to record information about the navigation paths of website visitors. The graph contains the frequent surfing paths that are required for mining TSPs. In addition, we devised a graph traverse algorithm based on the proposed graph structure to discover the TSPs. The experimental results show the proposed mining method is highly efficient to discover TSPs. © 2010 Elsevier Ltd. All rights reserved.

Liu C.-S.,National Taiwan University
Computers, Materials and Continua | Year: 2011

Only the left-boundary data of temperature and heat flux are used to estimate an unknown parameter function α(x) in Tt(x; t) = ∂ (α(x)Tx)=∂x+h(x; t), as well as to recover the right-boundary data. When α(x) is given the above problem is a well-known inverse heat conduction problem (IHCP). This paper solves a mixed-type inverse problem as a combination of the IHCP and the problem of parameter identification, without needing to assume a function form of α(x) a priori, and without measuring extra data as those used by other methods. We use the one-step Lie-Group Adaptive Method (LGAM) for the semi-discretizations of heat conduction equation, respectively, in time domain and spatial domain to derive algebraic equations, which are used to solve α(x) through a few iterations. To test the stability of the present LGAM we also add a random noise in the initial data. When α(x) is identified, a sideways approach is employed to recover the unknown boundary data. The convergence speed and accuracy are examined by numerical examples. Copyright © 2011 Tech Science Press.

Okuyama T.,National Taiwan University
Ecology and Evolution | Year: 2013

The relationship between foraging success and reproduction is commonly assumed to be linear in theoretical investigations. Although the exact relationship (e.g., linear or nonlinear) does not influence qualitative conclusions of models under some assumptions, an inclusion of individual behavioral variation can make it otherwise due to Jensen's inequality. In particular, a mechanism that stabilizes food web dynamics is generated when two conditions are satisfied: (1) the reproduction of predators experiences diminishing returns from foraging success (i.e., concave down relationship between foraging success and reproduction) and (2) foraging success variation among predator individuals increases with the predator density. However, empirical results that confirm these conditions are scarce. This study describes the mechanism as a hypothesis for stability and discusses some important considerations for empirical verifications of the mechanism. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.

Luh T.-Y.,National Taiwan University
Pure and Applied Chemistry | Year: 2012

Double-stranded polymeric ladderphanes are obtained by ring-opening metathesis polymerization (ROMP) of bisnorbornene derivatives by the first generation of Grubbs catalyst (G-I). A range of two- and three-dimensional organic and organometallic linkers are used to connect two norbornene units. The structures of these double-stranded polymers are proved by spectroscopic means and scanning tunneling microscopic (STM) images. Hydrolytic cleavages of these ladderphanes give the corresponding single-stranded polymers with the same degree of polymerization and polydispersity as those of the double-stranded counterparts. Helical polymeric ladderphanes are also synthesized similarly when chiral linkers are used. Strong intereactions between adjacent linkers have been revealed by their physical properties in these polymers. Chemical modification of ladderphanes is achieved by bisdihydroxylation, diimide reduction of double bonds, and electrochemical oxidation of linkers. Unsymmetrical ladderphanes with well-defined lengths and narrow dispersity are also obtained by replication and by sequential polymerization. © 2012 IUPAC.

Chang H.-H.,National Taiwan University
Ecological Economics | Year: 2012

The purpose of eco-labels is to encourage a move towards more environmentally friendly consumption patterns. The eco-label has been recognized as a means of promoting products with lower environmental impact. A considerable body of literature has focused on consumer demand for eco-label use: however, little attention has been paid to producers. Because the adoption decision is voluntary, a better understanding of producers' adoption behaviors towards eco-labels could significantly determine the effectiveness of the program. This paper contributes to this policy issue by assessing the impacts of the Taiwan Good Agricultural Products program, a combined eco-label and food traceability system, on the distribution of aquaculture producers' income in Taiwan. Using a unique aquaculture producer survey in Taiwan, we examine the extent to which label use may affect the level of income, income variability and income inequality of the producers. Our findings suggest that eco-label use increases income and that the effect is more pronounced for producers at the higher percentile range of income distribution. Label use also increases income variability, but no significant effect on income inequality is evident. © 2012 Elsevier B.V.

Chang Y.-W.,Fu Jen Catholic University | Huang M.-H.,National Taiwan University
Journal of the American Society for Information Science and Technology | Year: 2012

This study uses three bibliometric methods: direct citation, bibliographic coupling, and co-authorship analysis, to investigate interdisciplinary changes in library and information science (LIS) from 1978 to 2007. The results reveal that LIS researchers most frequently cite publications in their own discipline. In addition, half of all co-authors of LIS articles are affiliated with LIS-related institutes. The results confirm that the degree of interdisciplinarity within LIS has increased, particularly co-authorship. However, the study found sources of direct citations in LIS articles are widely distributed across 30 disciplines, but co-authors of LIS articles are distributed across only 25 disciplines. The degree of interdisciplinarity was found ranging from 0.61 to 0.82 with citation to references in all articles being the highest and that of co-authorship being the lowest. Percentages of contribution attributable to LIS show a decreasing tendency based on the results of direct citation and co-authorship analysis, but an increasing tendency based on those of bibliographic coupling analysis. Such differences indicate each of the three bibliometric methods has its strength and provides insights respectively for viewing various aspects of interdisciplinarity, suggesting the use of no single bibliometric method can reveal all aspects of interdisciplinarity due to its multifaceted nature. © 2011 ASIS&T.

Chi Y.,National Tsing Hua University | Tong B.,National Tsing Hua University | Tong B.,Anhui University of Technology | Chou P.-T.,National Taiwan University
Coordination Chemistry Reviews | Year: 2014

This review is aimed at updating the current advance of metal complexes bearing pyridyl azolates or relevant functionality. Of particular emphasis is the emerging metal complexes, which show bright prospect in the energy relevant issues such as organic light emitting diodes (OLEDs) and dye sensitized solar cells (DSCs). Our motive lies in the development of OLED phosphors as well as the realization of superior sensitizers in DSCs. It covers a great extension of azolates based derivatives as well as a large variety of core metal ions spanning from Re(I), Ru(II), Os(II), Ir(III), Pt(II) and to Cu(I). Their synthetic strategy, chemical/physical and photophysical properties and electroluminescence as a function of chelate or metal characteristics are systematically discussed. The potential applications are far-reaching in the wake of the previously unrecognized feature on harnessing the highly excited states, which are then realized by several new designs endowed with this unique property. Also, the interplay of the ligand design, i.e, the sameness and difference, between lighting and photovoltaic oriented metal complexes is highlighted. © 2014 Elsevier B.V.

Zuo F.,University of Washington | Williams S.T.,University of Washington | Liang P.-W.,University of Washington | Chueh C.-C.,University of Washington | And 3 more authors.
Advanced Materials | Year: 2014

A simple, low temperature solution process for Pb/Sn binary-metal perovskite planar-heterojunction solar cells is demonstrated. Sn inclusion substantially influences the band-gap, crystallization kinetics, and thin-film formation leading to a broadened light absorption and enhanced film coverage on ITO/PEDOT:PSS. As a result, the optimized device shows a PCE exceeding 10%, which is the best result for binary-metal perovskite solar cells so far. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lin C.-S.,National Taiwan University | Yang Y.,New York University
Nuclear Physics B | Year: 2011

Vortices in non-Abelian gauge field theory play essential roles in the mechanism of color confinement and are governed by systems of nonlinear elliptic equations of complicated structure. In this paper, we present a series of sharp existence and uniqueness theorems for multiple vortex solutions of the non-Abelian BPS equations over R2 and on a doubly periodic domain. Our methods are based on calculus of variations which may be used to analyze more extended problems. The necessary and sufficient conditions for the existence of a unique solution in the doubly periodic situation are expressed in terms of physical parameters involved explicitly. © 2011 Elsevier B.V.

Capart H.,National Taiwan University | Fraccarollo L.,University of Trento
Geophysical Research Letters | Year: 2011

We report laboratory experiments on intense bed-load driven by turbulent open-channel flows. Using high-speed cameras and a laser light sheet, we measured detailed profiles of granular velocity and concentration near the sidewall. The profiles provide new information on transport layer structure and its relation to the applied Shields stress. Contrary to expectations, we find that intense bed-load layers respond to changes in flow conditions by adjusting their granular concentration at the base, slightly above the bed. Two mechanisms account for the resulting behavior: stresses generated by immersed granular collisions, and equilibration of the otherwise unstable shear layer by density stratification. Without parameter adjustment, the deduced constitutive relations capture the responses of velocity, concentration, and layer thickness to a ten-fold increase in Shields stress. © 2011 by the American Geophysical Union.

Hwang B.-F.,China Medical University at Taichung | Lee Y.L.,National Taiwan University
Chest | Year: 2010

Background: There were limited studies concerning ambient air pollution exposure on development of bronchitic symptoms among children. These studies provided suggestive but inconclusive results. Therefore, the objective of this study is to assess the association between air pollutants and the prevalence of bronchitic symptoms in the Taiwan Children Health Study. Methods: We conducted a nationwide cross-sectional study of 5,049 Taiwanese children in 2007. Routine air pollution monitoring data were used for sulfur dioxide (SO2), nitrogen dioxides (NO2), ozone (O3), carbon monoxide (CO), and particles with an aerodynamic diameter ≤ 2.5 m m (PM2.5). The exposure parameters were calculated using the between-community 3-year average concentration. The effect estimates were presented as odds ratios (ORs) per interquartile changes for SO2, NO2, O3, CO, and PM2.5. Results: In the two-stage hierarchical model adjusting for confounding, the prevalence of bronchitic symptoms with asthma was positively associated with the between-community 3-year average concentrations of NO 2 (adjusted OR, 1.81 per 8.79 ppb; 95% CI, 1.14-2.86), and CO (OR, 1.31 per 105 ppb; 95% CI, 1.04-1.64). The prevalence of phlegm with no asthma was related to O3 (OR, 1.32 per 8.77 ppb; 95% CI, 1.06-1.63). Conclusions: The results suggest that long-term exposure to outdoor air pollutants, such as NO2, CO, and O3, may increase the prevalence of bronchitic symptoms among children. © 2010 American College of Chest Physicians.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Gut | Year: 2011

Background: The association between diabetes and gastric cancer has been rarely studied. Objective: To investigate gastric cancer mortality trends, the mortality rate ratios between patients with diabetes and the general population, and the risk factors for gastric cancer mortality in diabetic patients. Methods: In the Taiwanese general population from 1995 to 2006, age-standardised trends of gastric cancer mortality were evaluated, followed by calculation of age-sex-specific mortality rates. A total of 113 347 men with diabetes and 131 573 women with diabetes, aged ≥25 years and recruited in 1995-1998, were followed to 2006 for gastric cancer mortality. Age-sex-specific mortality rate ratios for diabetic patients versus the general population were calculated. Cox's regression was used to evaluate the risk factors among diabetic patients. Results: A decreasing trend of age-standardised gastric cancer mortality in the general population (p<0.0001) was observed from 1995 to 2006 for both sexes. A total of 627 diabetic men and 422 diabetic women died of gastric cancer, with a calculated mortality rate of 72.8 and 40.0 per 100 000 person-years, respectively. Mortality rate ratios showed a significantly higher risk in diabetic patients with a magnitude most remarkable at the youngest age: 1.52 (1.31-1.77), 1.58 (1.40-1.78) and 4.49 (3.93-5.12) for ≥75, 65-74 and 25-64 years old, respectively, for men; and 1.58 (1.32-1.90), 1.95 (1.67-2.27) and 3.65 (3.11-4.28), respectively, for women. In the diabetic patients, age and male sex were associated with gastric cancer mortality, but diabetes type, insulin use, and smoking were not. Body mass index and area of residence did not show consistent association. Diabetes duration was significantly predictive when those who died of gastric cancer within 5 years of diabetes diagnosis were excluded from analysis. Conclusions: Despite a decreasing age-standardised mortality trend in the general population, diabetic patients have a higher risk of gastric cancer mortality and this was most remarkable in the youngest age group of 25-64 years.

We demonstrated how to comprehensively translate the existing and updated scientific evidence on genomic discovery, tumour phenotype, clinical features, and conventional risk factors in association with breast cancer to facilitate individually tailored screening for breast cancer. We proposed an individual-risk-score-based approach that translates state-of-the-art scientific evidence into the initiators and promoters affecting onset and subsequent progression of breast tumour underpinning a novel multi-variable three-state temporal natural history model. We applied such a quantitative approach to a population-based Taiwanese women periodical screening cohort. Risk prediction for pre-clinical detectable and clinical-detected breast cancer was made by the two risk scores to stratify the underlying population to assess the optimal age to begin screening and the inter-screening interval for each category and to ascertain which high-risk group requires an alternative image technique. The risk-score-based approach significantly reduced the interval cancer rate as a percentage of the expected rate in the absence of screening by 30% and also reduced 8.2% false positive cases compared with triennial universal screening. We developed a novel quantitative approach following the principle of translational research to provide a roadmap with state-of-the-art genomic discovery and clinical parameters to facilitate individually tailored breast cancer screening.

Tsai F.-C.,Stanford University | Tsai F.-C.,National Taiwan University | Seki A.,Stanford University | Yang H.W.,Stanford University | And 4 more authors.
Nature Cell Biology | Year: 2014

Ca2+ signals control cell migration by regulating forward movement and cell adhesion. However, it is not well understood how Ca 2+ -regulatory proteins and second messengers are spatially organized in migrating cells. Here we show that receptor tyrosine kinase and phospholipase C signalling are restricted to the front of migrating endothelial leader cells, triggering local Ca2+ pulses, local depletion of Ca2+ in the endoplasmic reticulum and local activation of STIM1, supporting pulsatile front retraction and adhesion. At the same time, the mediator of store-operated Ca2+ influx, STIM1, is transported by microtubule plus ends to the front. Furthermore, higher Ca2+ pump rates in the front relative to the back of the plasma membrane enable effective local Ca2+ signalling by locally decreasing basal Ca2+. Finally, polarized phospholipase C signalling generates a diacylglycerol gradient towards the front that promotes persistent forward migration. Thus, cells employ an integrated Ca2+ control system with polarized Ca 2+ signalling proteins and second messengers to synergistically promote directed cell migration. © 2014 Macmillan Publishers Limited. All rights reserved.

Shyue K.-M.,National Taiwan University
Journal of Computational Physics | Year: 2010

We describe a simple mapped-grid approach for the efficient numerical simulation of compressible multiphase flow in general multi-dimensional geometries. The algorithm uses a curvilinear coordinate formulation of the equations that is derived for the Euler equations with the stiffened gas equation of state to ensure the correct fluid mixing when approximating the equations numerically with material interfaces. A γ-based and a α-based model have been described that is an easy extension of the Cartesian coordinates counterpart devised previously by the author [30]. A standard high-resolution mapped grid method in wave-propagation form is employed to solve the proposed multiphase models, giving the natural generalization of the previous one from single-phase to multiphase flow problems. We validate our algorithm by performing numerical tests in two and three dimensions that show second order accurate results for smooth flow problems and also free of spurious oscillations in the pressure for problems with interfaces. This includes also some tests where our quadrilateral-grid results in two dimensions are in direct comparisons with those obtained using a wave-propagation based Cartesian grid embedded boundary method. © 2010 Elsevier Inc.

Lowemark L.,National Taiwan University
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

Despite the fact that the trace fossil Zoophycos has been found in rocks from most of the Phanerozoic, little consensus has been reached on how and why this intricate burrow was constructed. The Cenozoic morphotypes of Zoophycos typically include a helically coiled spreite arranged around a vertical shaft connected to the sediment surface.Morphological details and environmental preferences of the Zoophycos producer were studied using 156 cores from the Norwegian and Greenland Seas in order to test the different ethological hypothesis proposed for this trace fossil. The spreiten were constructed during interglacial or interstadial intervals and consist of a repeated alternation of lamellae consisting of fine-grained pelleted material, and coarse-grained unpelleted material, respectively. Spreiten were encountered in vigorously bioturbated sediment, in turbidite layers, and in layers dominated by coarse ice-rafted debris. This indifference to the composition of the substrate effectively rules out ethological models based on different forms of deposit-feeding, and the large size and wide spacing of the whorls of the spreiten also make the cesspit model unlikely. Rather, the observed features best agree with a cache behaviour, where the main purpose of the deep penetration was to store food and to prevent access by other burrowers, likely combined with some gardening of microbes. However, no indubitable evidence of a reworking of the cached material could be found, and probably the answer to how the cache was accessed by the producer is to be found in the marginal tube. The difference in diameter between marginal tube and spreiten lamellae, together with the presence of both open and filled marginal tubes indicate that the marginal tube is the result of a far more complex behaviour than simply a lateral shift through the sediment. © 2015 Elsevier B.V.

Hu C.D.,National Taiwan University
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We proposed that in multiferroics, there exists a third long-range order besides the electric polarization and magnetic order. This long-range order reduces the symmetry of the spatial part of the wave functions of electrons. Thus the cancellation in the "spin-current" model can be avoided. As a result, the expectation value of electric polarization will be larger by an order of magnitude. We have derived a distinct form of electric polarization P- ∼- × ( sj ×sj+1), where Q- is the wave vector of this long-range order. © 2010 The American Physical Society.

Han J.-Y.,National Taiwan University
IEEE Geoscience and Remote Sensing Letters | Year: 2010

A novel approach for aligning multistation unregistered Light Detection and Ranging (LiDAR) point clouds is presented in this letter. It is designed to find the rigid rotations and translations between two data sets using hybrid conjugate features, including points, lines, planes, and groups of points. In addition, the proposed solution is expressed in a closed form, meaning that neither an initial alignment nor an iterative computation is required. Based on the numerical results from a real case study, it has been demonstrated that the proposed approach is capable of giving an efficient and reliable alignment solution. With the aforementioned advantages, the proposed technique can not only be directly implemented in a general analysis of LiDAR surveying data but will also particularly benefit those applications where classical point-based iterative analysis approaches are not practically feasible (e.g., an application without a sufficient number of connecting points). © 2006 IEEE.

Chern C.-H.,National Taiwan University
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

A family of the pair hopping models exhibiting the incompressible quantum liquid at fractional filling 1/ mD is constructed in D dimensional lattice. Except in one dimension, the lattice is the generalized edge-shared triangular lattice, for example the triangular lattice in two dimensions and tetrahedral lattice in three dimensions. They obey the symmetry, conservation of the center-of-mass position proposed by Seidel [Phys. Rev. Lett. 95, 266405 (2005)]. The finiteness of the excitation energy is calculated by the single mode approximation. © 2010 The American Physical Society.

Wang C.-S.,National Taiwan University | Otani Y.,Kanazawa University
Industrial and Engineering Chemistry Research | Year: 2013

Although the basic principles of fibrous filters have been well understood for capture of micron and submicron sized particles, questions arise when they are applied to nanoscale particles. In the first part of this review, the classical theory of fibrous filters is described with focus on the principles that are applicable to nanoparticle collection. The areas of recent developments reviewed include thermal rebound of nanoparticles and the effects of particle shape, aggregate morphology, flow regime, humidity, fiber size, and particle loading. One of the outstanding questions in nanoparticle collection is the particle size at which the effect of thermal rebound on collection efficiency can be observed. Theoretical calculations indicate that the effect probably can be observed only for particles smaller than 1 nm, but experimental confirmation is difficult at present because of lack of instruments for classifying and counting subnanoscale particles. Two promising devices based on filtration principles have been studied in recent years: multilayer filters and inertial fibrous filters. Multilayer filters, which are composed of nanofiber and microfiber mats, have potential to become an efficient and economical device for removing nanoparticles from gas streams. The inertial fibrous filter operates at high flow rates and relatively low pressure drop, thereby offering an attractive alternative to low-pressure impactors for nanoparticle sampling. Further development of these two types of filtration devices is needed to make them simple and reliable. © 2012 American Chemical Society.

In Asia, medicinal mushrooms have been popularly used as folk medicine and functional foods. In this study, our aim was to examine the inhibitory effects of six medicinal mushrooms on key enzymes (α-amylase and α-glucosidase) related to hyperglycemia; chemical profiles of bioactive extracts were also examined. The results showed that the n-hexane extract of Coriolus versicolor had the strongest anti-α-amylase activity, while the n-hexane extract of Grifola frondosa showed the most potent anti-α-glucosidase activity. Compared with acarbose, the anti-α-amylase activity of all mushroom extracts was weaker, however a stronger anti-α-glucosidase activity was noted. GC-MS analysis showed that the magnitude of potency of inhibiting α-glucosidase activity varied with the levels of oleic acid and linoleic acid present in the extracts. These findings were consistent with the IC50 values of these free fatty acids on inhibiting α-glucosidase activity. Taken together, this study suggests that oleic acid and linoleic acid could have contributed to the potent anti-α-glucosidase activity of selected medicinal mushrooms.

Viswanathan K.,National Taiwan University
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2011

In this report we describe the synthesis, characterization of fluorescent silica coated magnetic hybrid nanoparticles. These nanoparticles have been synthesized by combining the co-precipitation, polymerization and sol-gel technology with fluorescent dye. And their size can range from about 80 to 90. nm in diameter. The nanoparticles were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy, spectrofluorometer, X-ray diffraction patterns (XRD) and an energy-dispersive X-ray spectroscopy (EDS). Concluding, this report has provided simple and efficient method for the design of new water-soluble fluorescent silica coated magnetic hybrid nanoparticles for biomedical, analytical and catalytic applications. © 2011.

Chiang S.-H.,National Taiwan University | Chang K.-T.,Kainan University
Geomorphology | Year: 2011

In the western North Pacific, including Taiwan, typhoons (tropical cyclones) and rainfall rates are predicted to intensify as a result of climate change. Because typhoons are the major triggers of shallow landslides in Taiwan, landslide activity is expected to increase as global warming continues. To assess the worst scenario of landslide occurrence in a mountainous watershed till the end of the century, this study developed a method to select a global climate model (GCM) from 21 available GCMs and correct its monthly precipitation data, before downscaling annual maximum (24-h) rainfall from the corrected GCM data as input to the factor-of-safety model for landslide prediction. Average annual maximum rainfall is expected to increase from 322. mm in 1960-2008 to 371. mm in 2010-2099. Average total unstable area is expected to increase from 1135. ha in 1960-2008 to 1280. ha in 2010-2099, a 12% increase. As a first attempt to assess landslide activity due to global warming, this study is useful as a reference for watershed management in Taiwan. The results must be evaluated in light of uncertainties caused by the correction and downscaling of GCM data and the input parameters to the slope stability model. © 2011 Elsevier B.V.

Fang S.-H.,Yuan Ze University | Lin T.,National Taiwan University
IEEE Transactions on Mobile Computing | Year: 2012

This paper presents a novel approach to building a WLAN-based location fingerprinting system. Our algorithm intelligently transforms received signal strength (RSS) into principal components (PCs) such that the information of all access points (APs) is more efficiently utilized. Instead of selecting APs, the proposed technique replaces the elements with a subset of PCs to simultaneously improve the accuracy and reduce the online computation. Our experiments are conducted in a realistic WLAN environment. The results show that the mean error is reduced by 33.75 percent, and the complexity by 40 percent, as compared to the existing methods. Moreover, several benefits of our algorithm are demonstrated, such as requiring fewer training samples and enhancing the robustness to RSS anomalies. © 2006 IEEE.

Azamathulla H.M.,Universiti Sains Malaysia | Wu F.-C.,National Taiwan University
Applied Soft Computing Journal | Year: 2011

This paper presents the support vector machine approach to predict the longitudinal dispersion coefficients in natural rivers. Collected published data from the literature for the dispersion coefficient for wide range of flow conditions are used for the development and testing of the proposed method. The proposed SVM approach produce satisfactory results with coefficient of determination = 0.9025 and root mean square error = 0.0078 compared to existing predictors for dispersion coefficient. © 2010 Elsevier B.V. All rights reserved.

Introduction: Happiness and social inclusion are important indicators of social sustainability, as recommended in the Sustainable Development Goals; however, little is known about the social sustainable development of ethnic minorities. To fill this knowledge gap, special attention is paid to understanding the issues of social exclusion and happiness in relation to the indigenous peoples in Taiwan. Methods: Data used were drawn from a nationwide representativeness survey of the Taiwanese Indigenous People in 2007; it included 2,200 respondents. This study employed binary logistic regression to examine the effects of different domains of social exclusion on the likelihood of perceiving happiness; other exogenous factors, were controlled. Results: The results show that among the respondents, mountain indigenous peoples, females, the elderly and those who are healthier, wealthier, highly educated, possessing western beliefs, and are more likely to be happy, compared to their counterparts. As expected, the results reveal that the likelihood of being happy is higher for those who have received medical benefits, as well as those persons without housing problems or financial difficulties, compared to their excluded counterparts. However, no significant association is found between happiness and some social exclusion domains, such as child and youth benefits, and unemployment benefits. Conclusions: The disengagement of the indigenous peoples in mainstream society, with respect to the accessibility of welfare provisions, is a crucial element in regard to social exclusion and happiness. Several policy implications for the social sustainability of indigenous peoples can be inferred from these findings. For example, providing a mobile clinical tour, on-site health counseling, or homecare service can contribute to the removal of institutional and geographic barriers to medical welfare provisions for the mountain indigenes. Moreover, the government may devote more welfare resources to assist indigenous families and tribal communities to develop their own social safety net, instead of the individual-oriented welfare provisions. © 2015 Jiun-Hao Wang.

Lu C.-Y.D.,National Taiwan University
Physical Review Letters | Year: 2012

The dynamics of the multilamellar vesicle (MLV) is analyzed theoretically, where membrane interaction squeezes the solvent to flow between the neighboring membranes. With the applied affine shear, the dynamic free energy density of the MLV develops a minima, which selects the MLV size. The model predicts a terminal shear rate, below which the metastable MLV exists. The scaling relations for the MLV size and the terminal shear are both consistent with the experiments. © 2012 American Physical Society.

Liu C.-S.,National Taiwan University
International Journal of Heat and Mass Transfer | Year: 2012

We consider an inverse problem for the reconstruction of a past unknown time-dependent heat source H(t), t < t f, in a heat conduction equation T t(x,t) = T xx(x,t) + H(t) with the aid of an extra measurement of temperature gradient on the left-boundary, where a final time condition is measured at the present terminal time t f. This inverse problem is quite difficult to be solved numerically owing to a twofold ill-posedness, as a combination of the backward heat conduction problem and the inverse heat source identification problem, which is abbreviated as inverse heat source/backward heat conduction problem (IHSBHCP). The new method proposed here, namely the Lie-group shooting method (LGSM), is examined through the tests by several numerical examples. Although the recovery of an unknown heat source is carried out under a presently measured temperature at a final time and under a large measurement noise both imposed on the final time data and all boundary data, the LGSM still works effectively and accurately. The accuracy in the reconstruction of H(t) is almost uneffected by different levels of noise. © 2011 Elsevier Ltd. All rights reserved.

Sun G.,University of Massachusetts Boston | Soref R.A.,Air Force Research Lab | Cheng H.H.,National Taiwan University
Optics Express | Year: 2010

This paper presents modeling and simulation of a silicon-based group IV semiconductor injection laser diode in which the active region has a multiple quantum well structure formed with Ge0.9Sn0.1 quantum wells separated by Ge0.75Si0.1Sn0.15 barriers. These alloy compositions were chosen to satisfy three conditions simultaneously: a direct band gap for Ge0.9Sn0.1, type-I band alignment between Ge0.9Sn0.1 and Ge0.75Si 0.1Sn0.15, and a lattice match between wells and barriers. This match ensures that the entire structure can be grown strain free upon a relaxed Ge0.75Si0.1Sn0.15 buffer on a silicon substrate - a CMOS compatible process. Detailed analysis is performed for the type I band offsets, carrier lifetime, optical confinement, and modal gain. The carrier lifetime is found to be dominated by the spontaneous radiative process rather than the Auger process. The modal gain has a rather sensitive dependence on the number of quantum wells in the active region. The proposed laser is predicted to operate at 2.3 μm in the mid infrared at room temperature. © 2010 Optical Society of America.

Hsu S.,National Taiwan University
Journal of Computer Assisted Learning | Year: 2010

There is no unified view about how teachers' integration of information and communication technology (ICT) should be measured. While many instruments have focused on the technological aspects, recent studies have suggested teachers' pedagogical considerations, professional development, and emerging ethical and safety issues should be included when assessing teachers' ICT literacy. Using the performance standards created by the International Society for Technology in Education, a group of Taiwanese teachers developed equivalent items. After consulting expert panels and interviewing teachers, a scale was constructed. Using this instrument, 3729 teachers from grades 1 through 9 in Taiwan were sampled. Half of the data was analysed by exploratory factor analysis to find the underpinning structure, and the second half was analysed by confirmatory factor analysis to verify the subscales. The results confirmed six subscales for teachers' ICT integration: (1) information collection and preparation; (2) material production and troubleshooting; (3) communication and sharing; (4) planning, teaching and evaluation; (5) professional development and self-study; and (6) ethical, health and safety issues. Using two teacher attributes, school levels and course or degree obtained, the scale was further verified for its feasibility. The established scale examines the existing concerns for technology, pedagogy and professional development at once with a new addition of ethical and safety issues, which demand growing attention in teachers of future generation. © 2010 Blackwell Publishing Ltd.

We propose a method for detecting evolutionary forces underlying community assembly by quantifying the strength of community–environment relationships hierarchically along taxonomic ranks. This approach explores the potential role of phylogenetic conservatism on habitat preferences: wherein, phylogenetically related taxa are expected to exhibit similar environmental responses. Thus, when niches are conserved, broader taxonomic classification should not diminish the strength of community–environment relationships and may even yield stronger associations by summarizing occurrences and abundances of ecologically equivalent finely resolved taxa. In contrast, broader taxonomic classification should weaken community–environment relationships when niches are under great divergence (that is, by combining finer taxa with distinct environmental responses). Here, we quantified the strength of community–environment relationships using distance-based redundancy analysis, focusing on soil and seawater prokaryotic communities. We considered eight case studies (covering a variety of sampling scales and sequencing strategies) and found that the variation in community composition explained by environmental factors either increased or remained constant with broadening taxonomic resolution from species to order or even phylum level. These results support the niche conservatism hypothesis and indicate that broadening taxonomic resolution may strengthen niche-related signals by removing uncertainty in quantifying spatiotemporal distributions of finely resolved taxa, reinforcing the current notion of ecological coherence in deep prokaryotic branches.The ISME Journal advance online publication, 13 May 2016; doi:10.1038/ismej.2016.78. © 2016 International Society for Microbial Ecology

Lee W.-C.,National Taiwan University
Epidemiology | Year: 2012

Many epidemiologists are familiar with Rothman's sufficient component cause model. In this paper, I propose a new index for this model, the completion potential index I show that, with proper assumptions (monotonicity, independent competing causes, proportional hazards), completion potentials for various classes of sufficient causes are estimable from routine epidemiologic data (cohort, case-control or time-to-event data). I discuss the advantage of the completion potential index over indices of rate ratio, rate difference, causal-pie weight, population attributable fraction, and attributable fraction within the exposed population. Hypothetical and real data examples are used. The completion potential index proposed here allows better characterization of complex interactive effects of multiple monotonic risk factors. © 2012 Lippincott Williams & Wilkins, Inc.

Chen S.-S.,National Taiwan University
Energy Economics | Year: 2010

This paper investigates whether a higher oil price pushes the stock market into bear territory, by using time-varying transition-probability Markov-switching models. It examines different measures of oil price shocks. Empirical evidence from monthly returns on the Standard & Poor's S&P 500 price index suggests that an increase in oil prices leads to a higher probability of a bear market emerging. © 2009 Elsevier B.V. All rights reserved.

Liu C.-S.,National Taiwan University
Numerical Heat Transfer, Part B: Fundamentals | Year: 2011

We consider a backward heat conduction problem (BHCP) in a slab, subject to noisy data at final time. The BHCP is known to be highly ill-posed. In order to stably solve the BHCP by a numerical method, we employ a new post-conditioner in the linear system obtained by the method of fundamental solutions (MFS), and then we use the conjugate gradient method (CGM) to solve the post-conditioned linear system to determine the unknown coefficients used in the expansion by the MFS. The method can retrieve the initial data rather well, with a certain degree of accuracy. Several numerical examples of the BHCP demonstrate that the present method is applicable, even for those of strongly ill-posed problems with a large value of final time and with large noise. We also demonstrate that the CGM alone is not enough to accurately recover the initial temperature. Copyright © Taylor & Francis Group, LLC.

Chen H.-L.,National Taiwan University | Doty D.,California Institute of Technology
Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms | Year: 2012

We study the role that parallelism plays in time complex-ity of variants of Winfree's abstract Tile Assembly Model (aTAM), a model of molecular algorithmic self-assembly. In the "hierarchical" aTAM, two assemblies, both consisting of multiple tiles, are allowed to aggregate together, whereas in the "seeded" aTAM, tiles attach one at a time to a grow-ing assembly. Adleman, Cheng, Goel, and Huang (Running Time and Program Size for Self-Assembled Squares, STOC 2001) showed how to assemble an n x n square in O(n) time in the seeded aTAM using O(log n/log log n) unique tile types, where both of these parameters are optimal. They asked whether the hierarchical aTAM could allow a tile system to use the ability to form large assemblies in parallel before they attach to break the Ω(n) lower bound for assembly time. We show that there is a tile system with the optimal O(log n/log log n) tile types that assembles an n x n square using O(log 2 n) parallel "stages", which is close to the optimal Ω(log n) stages, forming the final n x n square from four n/2 x n/2 squares, which are themselves recursively formed from n/4 x n/4 squares, etc. However, despite this nearly maximal parallelism, the system requires superlinear time to assemble the square. We extend the definition of partial order tile systems studied by Adleman et al. in a natural way to hierarchical assembly and show that no hierarchical partial order tile system can build any shape with diameter N in less than time Ω (N), demonstrating that in this case the hierarchical model affords no speedup whatsoever over the seeded model. We also strengthen the Ω(N) time lower bound for deterministic seeded systems of Adleman et al. to nondeterministic seeded systems. Finally, we show that for infinitely many n, a tile system can assemble an n x n′ rectangle, with n > n′, in time O(n 4/5 log n), breaking the linear-time lower bound that applies to all seeded systems and partial order hierarchical systems. Copyright © SIAM.

Sun S.,Fudan University | Sun S.,National Taiwan University | He Q.,Fudan University | Xiao S.,Fudan University | And 3 more authors.
Nature Materials | Year: 2012

The arbitrary control of electromagnetic waves is a key aim of photonic research. Although, for example, the control of freely propagating waves (PWs; refs 7-10) and surface waves (SWs; refs 7-10) has separately become possible using transformation optics and metamaterials, a bridge linking both propagation types has not yet been found. Such a device has particular relevance given the many schemes of controlling electromagnetic waves at surfaces and interfaces, leading to trapped rainbows, lensing, beam bending, deflection, and even anomalous reflection/refraction. Here, we demonstrate theoretically and experimentally that a specific gradient-index meta-surface can convert a PW to a SW with nearly 100% efficiency. Distinct from conventional devices such as prism or grating couplers, the momentum mismatch between PW and SW is compensated by the reflection-phase gradient of the meta-surface, and a nearly perfect PW-SW conversion can happen for any incidence angle larger than a critical value. Experiments in the microwave region, including both far-field and near-field characterizations, are in excellent agreement with full-wave simulations. Our findings may pave the way for many applications, including high-efficiency surface plasmon couplers, anti-reflection surfaces, light absorbers, and so on. © 2012 Macmillan Publishers Limited. All rights reserved.

The trench structure is designed and used to release the process induced stress, resulted from the different material thermal expansion coefficients, in the three-dimensional integral circuits (3-DICs). The stress in the designed trench structure is measured by the atomic force microscope-Raman technique experimentally and simulated by the full process simulation model. With the help of this simulation model, the optimized trench structure near the copper-filled through silicon via (TSV) is designed and reported. The experimental data demonstrate that the compressive stress near the TSV can be reduced from 600 MPa to 150 MPa, and the corresponding keep-out zone can also be decreased ∼4 times with the designed trench structure having the depth of 10 μm and the spacing distance of 8 μm to the TSV. This work provides one potential solution to release the process induced stress for the real application of 3-DICs. © 2013 AIP Publishing LLC.

Chung C.-D.,National Taiwan University
IEEE Transactions on Communications | Year: 2010

Spectrally precoded orthogonal frequency-division multiplexing (OFDM) and constant-envelope OFDM (CEOFDM) are two modified OFDM formats that enhance the signaling features of OFDM, while allowing for the efficient implementation by discrete Fourier transform and the insertion of guard intervals to counteract channel dispersion. The spectrally precoded OFDM signal provides very small power spectral sidelobes decaying asymptotically as f-2J-2 with J integer-valued design parameter, thereby suppressing sidelobe powers effectively and achieving higher spectral efficiency than nonprecoded rectangularly-pulsed OFDM which has power spectral sidelobes decaying asymptotically as f -2. The CE-OFDM signal exhibits a unity peak-to-average power ratio, and thus enables the efficient use of transmitters power amplifier. In this paper, a specific CE-OFDM block signaling format is proposed to incorporate spectral precoding with an aim to suppressing sidelobe powers more effectively than conventional nonprecoded CE-OFDM. The general constraint on spectral precoding is developed to ensure that the power spectral sidelobes of the spectrally precoded CE-OFDM block signal with arbitrary data statistics decay asymptotically as f-2J-2. Some spectral codes previously found for spectrally precoded OFDM are shown to meet the constraint and thus suited for spectrally precoded CEOFDM. Specifically, spectral performance is analyzed for the spectrally precoded CE-OFDM block signal with independent and identically distributed data to illustrate the prevailing spectral advantage. The corresponding receiver is also developed to demodulate the spectrally precoded CE-OFDM block signal over dispersive channels. © 2006 IEEE.

Liu P.-L.,National Taiwan University
Computer Assisted Language Learning | Year: 2014

This study examined the influence of morphological instruction in an eye-tracking English vocabulary recognition task. Sixty-eight freshmen enrolled in an English course and received either traditional or morphological instruction for learning English vocabulary. The experimental part of the study was conducted over two-hour class periods for seven weeks. To investigate the effects of morphological instruction on English vocabulary learning, all participants completed an English vocabulary recognition task. Fixation time and path during recognition were recorded with an eye-tracking device. A comparison between the post-test performances of both groups showed that the experimental group obtained a considerably higher score on the target eye-tracking vocabulary test. The results of the eye-tracking record showed that participants who received morphological instruction had longer fixation times on the vocabulary and morpheme areas compared with the group that received traditional instruction. In addition, the experimental group had dense fixation paths on the morpheme areas of vocabulary. These results indicate that participants who received morphological instruction considered the morphemes as inferring references to read and inferred unknown words with greater success. © 2014 Taylor & Francis.

Chen S.H.,Duke University | Chan N.-L.,National Taiwan University | Hsieh T.-S.,Duke University | Hsieh T.-S.,Academia Sinica, Taiwan
Annual Review of Biochemistry | Year: 2013

DNA topoisomerases are nature's tools for resolving the unique problems of DNA entanglement that occur owing to unwinding and rewinding of the DNA helix during replication, transcription, recombination, repair, and chromatin remodeling. These enzymes perform topological transformations by providing a transient DNA break, formed by a covalent adduct with the enzyme, through which strand passage can occur. The active site tyrosine is responsible for initiating two transesterifications to cleave and then religate the DNA backbone. The cleavage reaction intermediate is exploited by cytotoxic agents, which have important applications as antibiotics and anticancer drugs. The reactions mediated by these enzymes can also be regulated by their binding partners; one example is a DNA helicase capable of modulating the directionality of strand passage, enabling important functions like reannealing denatured DNA and resolving recombination intermediates. In this review, we cover recent advances in mechanistic insights into topoisomerases and their various cellular functions. © 2013 by Annual Reviews. All rights reserved.

Yang T.-L.,National Taiwan University Hospital | Yang T.-L.,National Taiwan University
International Journal of Molecular Sciences | Year: 2011

Chitin-based materials and their derivatives are receiving increased attention in tissue engineering because of their unique and appealing biological properties. In this review, we summarize the biomedical potential of chitin-based materials, specifically focusing on chitosan, in tissue engineering approaches for epithelial and soft tissues. Both types of tissues play an important role in supporting anatomical structures and physiological functions. Because of the attractive features of chitin-based materials, many characteristics beneficial to tissue regeneration including the preservation of cellular phenotype, binding and enhancement of bioactive factors, control of gene expression, and synthesis and deposition of tissue-specific extracellular matrix are well-regulated by chitin-based scaffolds. These scaffolds can be used in repairing body surface linings, reconstructing tissue structures, regenerating connective tissue, and supporting nerve and vascular growth and connection. The novel use of these scaffolds in promoting the regeneration of various tissues originating from the epithelium and soft tissue demonstrates that these chitin-based materials have versatile properties and functionality and serve as promising substrates for a great number of future applications. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

Chou C.,National Taiwan University | Hsueh Y.-C.,Academia Sinica, Taiwan
Journal of Climate | Year: 2010

Mechanisms of northward-propagating intraseasonal oscillations (ISOs) over the Indian Ocean (IO) and the western North Pacific (WNP) are examined for the possibility of their existence in observations. They include the following: 1) the vorticity advection effect, which is associated with the advection of anomalous baroclinic vorticity by mean baroclinic meridional winds; 2) the vertical wind shear effect, which is the vertical advection associated with the meridional gradient of baroclinic divergence and mean easterly vertical wind shear; 3) the moisture advection effect induced by mean flow; and 4) the air-sea interaction via surface latent heat flux. Because of differences in mean state, the influence of each mechanism on the northward-propagating ISOs is different between the IO and the WNP. The vorticity advection effect is consistently found over both the IO and the WNP, while the air-sea interaction has different impacts on the northward-propagating ISOs over the IO and the WNP. The vertical wind shear effect and the moisture advection effect are relatively important over the IO but not over the WNP. Processes to determine changes in SST are also different between the IO and the WNP. Over the IO, SST is mainly associated with surface solar radiation. Wind-stirring effects, surface latent heat flux, and subsurface water entrainment are secondary. Over the WNP, wind-stirring effects become important, but surface solar radiation is secondary. © 2010 American Meteorological Society.

Enkhbat T.,Mongolian Academy of science | Enkhbat T.,National Taiwan University
Journal of High Energy Physics | Year: 2014

The presence of colored particles can affect both the single and the pair Higgs productions substantially. For scalar particles, this happens if their portal couplings to the Standard Model Higgs are large and their masses are not too high. In the present work these processes are studied in the case of several leptoquarks which may appear in many beyond Standard Model theories. It is found that the constraints on the portal couplings from the single Higgs production and the decays to various channels measured by the LHC experiments still allow increased Higgs pair production rate. For the masses in the range from 180 GeV to 300 GeV, depending on the strength of such portal couplings, the Higgs pair production may reach an order to several hundred in magnitude larger rate than the Standard Model case for the 8 TeV run. Therefore, combined with the on going searches for leptoquarks by both the CMS and ATLAS, this is one of the possible scenarios to be probed directly by the current data. The current study demonstrates that if colored scalars modify scalar potentials through portal couplings, which has been studied for variety of motivations such as playing a potentially important role in electroweak phase transition, composite models or radiative neutrino masses, this fact may appear as the modified Higgs pair production. © 2014 The Author(s).

Lee M.-Y.,National Taiwan University | Hsu H.-H.,Academia Sinica, Taiwan
Journal of Climate | Year: 2013

A multidecadal geopotential height pattern in the upper troposphere of the extratropical Northern Hemisphere (NH) is identified in this study. This pattern is characterized by the nearly zonal symmetry of geopotential height and temperature between 358 and 658N and the equivalent barotropic vertical structure with the largest amplitude in the upper troposphere. This pattern is named the Eurasian-Pacific multidecadal oscillation (EAPMO) to describe its multidecadal time scale and the largest amplitudes over Eurasia and the North Pacific. Although nearly extending over the entire extratropics, theEAPMOexhibits larger amplitudes over western Europe, East Asia, and the North Pacific with a zonal scale equivalent to zonal wavenumbers 4 and 5. The zonally asymmetric perturbation tends to amplify over the major mountain ranges in the region, suggesting a significant topographic influence. The EAPMO has fluctuated concurrently with the Atlantic multidecadal oscillation (AMO) at least since the beginning of the twentieth century. The numerical simulation results suggest that the EAPMO could be induced by the AMO-like sea surface temperature anomaly and strengthened regionally by topography, especially over the Asian highland region, although the amplitude was undersimulated. This study found that the multidecadal variability of the upper-tropospheric geopotential height in the extratropical NH is much more complicated than in the tropics and the Southern Hemisphere (SH). It takes both first (warming trend) and second (multidecadal) EOFs to explain the multidecadal variability in the extratropicalNH, while only the firstEOF, which exhibited a warming trend, is sufficient for the tropics and SH. © 2013 American Meteorological Society.

Chern R.-L.,National Taiwan University
Optics Express | Year: 2013

The feature of spatial dispersion in periodic layered metamaterials is theoretically investigated. An effective medium model is proposed to derive the nonlocal effective permittivity tensor, which exhibits drastic variations in the wave vector domain. Strong spatial dispersion is found in the frequency range where surface plasmon polaritons are excited. In particular, the nonlocal effect gives rise to additional waves that are identified as the bonding or antibonding modes with symmetric or antisymmetric surface charge alignments. Spatial dispersion is also manifest on the parabolic-like dispersion, a non-standard type of dispersion in the medium. The associated negative refraction and backward wave occur even when the effective permittivity components are all positive, which is considered a property not available in the local medium. © 2013 Optical Society of America.

Lu L.,National Taiwan University
Educational Gerontology | Year: 2011

We aimed to explore older people's subjective leisure experiences and to further examine associations of such experiences with their depressive symptoms in Taiwan. Known correlates of depression, such as demographics, physical health, and social support, were taken into account. Face-to-face interviews were conducted to collect data using structured questionnaires from a national representative sample of community older people (N=1308, aged 65+). We found that (a) being female, older, single, less educated, and having lower family income were demographic risk factors of depression; (b) worse physical health, lack of independent functioning in Activities of Daily Living (ADL), and disability were related to more depressive symptoms; (c) greater social support was related to fewer depressive symptoms; (d) having controlled for effects of demographics, physical health, and social support, positive leisure experiences were independently related to fewer depressive symptoms.Thebenefits of meaningful leisure pursuits for successful aging are discussed. © Taylor & Francis Group, LLC.

Chu H.T.,National Taiwan University
BMC genomics | Year: 2012

Mitochondrial dysfunction is associated with various aging diseases. The copy number of mtDNA in human cells may therefore be a potential biomarker for diagnostics of aging. Here we propose a new computational method for the accurate assessment of mtDNA copies from whole genome sequencing data. Two families of the human whole genome sequencing datasets from the HapMap and the 1000 Genomes projects were used for the accurate counting of mitochondrial DNA copy numbers. The results revealed the parental mitochondrial DNA copy numbers are significantly lower than that of their children in these samples. There are 8%~21% more copies of mtDNA in samples from the children than from their parents. The experiment demonstrated the possible correlations between the quantity of mitochondrial DNA and aging-related diseases. Since the next-generation sequencing technology strives to deliver affordable and non-biased sequencing results, accurate assessment of mtDNA copy numbers can be achieved effectively from the output of whole genome sequencing. We implemented the method as a software package MitoCounter with the source code and user's guide available to the public at http://sourceforge.net/projects/mitocounter/.

Chern R.-L.,National Taiwan University | Han D.,Chongqing University
Optics Express | Year: 2014

Based on the effective medium model, nonlocal optical properties in periodic lattice of graphene layers with the period much less than the wavelength are investigated. Strong nonlocal effects are found in a broad frequency range for TM polarization, where the effective permittivity tensor exhibits the Lorentzian resonance. The resonance frequency varies with the wave vector and coincides well with the polaritonicmode. Nonlocal features are manifest on the emergence of additional wave and the occurrence of negative refraction. By examining the characters of the eigenmode, the nonlocal optical properties are attributed to the excitation of plasmons on the graphene surfaces. © 2014 Optical Society of America.

Liu C.-S.,National Taiwan University
Numerical Heat Transfer, Part B: Fundamentals | Year: 2011

We consider an inverse problem for numerically estimating a spatial-dependence heat conductivity α(x) in Tt(x, t) = ∂[α(x)Tx]/∂x + h(x, t), 0 < t < tf, 0 < x; < ℓ α(x) is assumed to be a continuous function of x, and (ℓ) is given. An iterative Lie-group adaptive method (LGAM) is developed, which can be used to find α(x) at the spatially discretized locations xi, requiring only a few measured temperature data at a final time tf as a target to select a suitable value of the parameter r ∈ [0, 1] appearing in the present method. The new method has three advantages in that no a priori information of the heat conductivity function is required, only a few extra data are measured, and it is robust againt noise. The accuracy and efficiency of the present method are confirmed by comparing the estimated results with some exact solutions. Copyright © 2011 Taylor & Francis Group, LLC.

Liu C.-S.,National Taiwan University
International Journal of Heat and Mass Transfer | Year: 2014

We consider an inverse problem for detecting an unknown time-dependent heat source in real-time for a nonlinear heat conduction equation, with the aid of an extra measurement of temperature at an internal point. After a finite difference discretization of governing equation into ordinary differential equations, we recast them and the measured data as a set of differential algebraic equations (DAEs), which is a novel view of the inverse heat source problem. Then we solve the resultant DAEs by a GL(n,R) Lie-group method, which can be used as an on-line estimator to detect unknown heat source of nonlinear heat conduction equation, by using only a real-time measurement of internal temperature under a randomly noisy disturbance. The estimated results obtained by the novel Lie-group differential algebraic equations (LGDAE) method are quite promising and robust enough against large random noises. © 2014 Elsevier Ltd. All rights reserved.

Liu C.-S.,National Taiwan University
International Journal of Heat and Mass Transfer | Year: 2014

The present study recovers a time-dependent heat source H(t) in ut(x,t)=uxx(x,t)+H(t), under measured initial heat flux, and Cauchy boundary conditions. The supplementary initial data are assumed to be analytic continuation ones being obtained by means of measurement, which are not given arbitrarily. We first transform the above problem into an inverse heat conduction problem without having the right-boundary value, and then, further transform it into another inverse heat source problem that we need to find F(t) in Tt(x,t)=Txx(x,t)-xF(t)/ℓ with measured initial and boundary conditions. By using the GL(n,R) Lie-group differential algebraic equations (LGDAE) method to integrate the resultant ordinary differential equations with a priori bound |F(t)|≤Fmax, we can fast recover H(t) in real time. The accuracy and efficiency are assessed and confirmed by comparing the exact solutions with recovered results, where a large noise up to 10% or 20% is imposed on the input measured data. © 2014 Elsevier Ltd. All rights reserved.

Lin J.,Fu Jen Catholic University | Lin J.,National Taiwan University
Clinical Gastroenterology and Hepatology | Year: 2014

Gastric cancer (GC) remains the leading cause of cancer mortality worldwide. Conceivably, early diagnosis may be achievable through screening of the high-risk population. Therefore, it is important to identify individuals harboring premalignant lesions that include atrophic gastritis, intestinal metaplasia, and mucosal dysplasia. The age threshold for GC screening depends on the regional incidence and the individual risk. In high-incidence countries such as Japan and Korea, the age to screen GC may be as early as 40 years. The mass screening by endoscopy in these countries would be able to detect a substantial portion of patients with early GCs as well as precancerous lesions. For the purpose of eliminating GC, however, these screening programs should be conducted in conjunction with Helicobacter pylori eradication. In low-incidence countries, it seems feasible to adopt a stepwise approach to identify high-risk individuals at first. The initial screening should focus on epidemiologic factors, genetic or hereditary risks, and the status of H pylori infection. Measurement of serum pepsinogen I and II and gastrin may detect atrophic gastritis in a noninvasive manner. Patients with these premalignant lesions should then receive endoscopic examination and enter surveillance. To date, there is no cost-effective strategy for an average-risk individual from a population with low incidence of GC, and therefore screening is unwarranted and cannot be recommended for them. © 2014 AGA Institute.

Huang P.,CAS Institute of Atmospheric Physics | Chou C.,National Taiwan University | Huang R.,CAS Institute of Atmospheric Physics
Journal of Climate | Year: 2011

The seasonal modulation of tropical intraseasonal oscillation (TISO) on tropical cyclone (TC) geneses over the western North Pacific Ocean (WNP) is investigated in three periods of the WNP TC season: May-June (MJ), July-September (JAS), and October-December (OND). The modulation of the TISO-TC geneses over the WNP is strong in MJ, while it appears weaker in JAS and OND. In MJ, TISO propagates northward via two routes, the west route through the South China Sea and the east route through the WNP monsoon trough region, which are two clustering locations of TC geneses. TISO can synchronously influence most TC geneses over these two regions. In JAS, however, the modulation is out of phase between the monsoon trough region and the East Asian summer monsoon region, as well as the WNP subtropical high region, as a result of further northward propagation of TISO and scattered TC geneses. The TISO-TC genesis modulation in each individual region is comparable to that in MJ, although the modulation over the entire WNP in JAS appears weaker. In OND, TISO has a stronger influence on TC geneses west than east of 1508E because TISO decays and its convection center located at the equator is out of the TC genesis region when propagating eastward into east of 1508E. Midlevel relative humidity is the primary contribution to the modulations of TISO on the genesis environment, while vorticity could contribute to the modulation over the subtropics in JAS. © 2011 American Meteorological Society.

Campagnola P.J.,University of Connecticut Health Center | Dong C.-Y.,National Taiwan University
Laser and Photonics Reviews | Year: 2011

In this review, the authors discuss the underlying principles of SHG and specific factors that affect the generation properties and describe the essential components of a SHG instrument. In addition, results on the recent progress and impact SHG microscopy has made in different areas of biology and medicine are presented. In particular, the authors focus on disease diagnosis and basic research associated with connected tissues, musculo-skeletal disorders, and epithelial cancers. The presentation is concluded by offering a perspective on the future technical development of SHG microscopy and additional forefronts to be addressed.In this review, the underlying principles of second harmonic generation (SHG) are discussed and specific factors that affect the generation properties and describe the essential components of a SHG instrument. In addition, results on the recent progress and impact SHG microscopy has made in different areas of biology and medicine are presented. In particular, a focus is set on disease diagnosis and basic research associated with connected tissues, musculo-skeletal disorders, and epithelial cancers. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hou W.-S.,National Taiwan University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

Drawing the analogy of replacing the nucleon by heavy chiral quark Q, the pion by Goldstone boson G, and πNN coupling by GQQ coupling, we construct a statistical model for QQ̄→nG annihilation, i.e., into n longitudinal weak bosons. This analogy is becoming prescient since the LHC direct bound m Q>611GeV implies strong Yukawa coupling. Taking m Q∈(1,2)TeV, the mean number 〈n G〉 ranges from 6 to over 10, with negligible two or three boson production. With individual t′ or b′ decays suppressed either by phase space or quark mixing, and given the strong Yukawa coupling, QQ̄→nV L is the likely outcome for very heavy QQ̄ production at the LHC. © 2012 American Physical Society.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Metabolism: Clinical and Experimental | Year: 2012

The objective was to evaluate non-Hodgkin lymphoma (NHL) mortality trends and mortality rate ratios between diabetes patients and the general population, and to study NHL risk factors among diabetes patients in Taiwan. A cohort of 80 397 patients with type 2 diabetes mellitus older than 45 years was recruited in 1995-1998 and followed up until 2006. Age-standardized NHL mortality in 1995-2006 was calculated. Non-Hodgkin lymphoma risk factors in diabetes patients were evaluated using Cox regression. Age-standardized NHL mortality trend was steady. Eighty-two male and 69 female diabetes patients died of NHL (crude mortality rates, 35.1 and 23.0 per 100 000 person-years, respectively; corresponding overall mortality rate ratios comparing diabetes patients to the general population, 2.06 and 2.14). The mortality rate ratios were 1.47, 2.33, and 2.78 for men aged at least 65, 55 to 64, and 45 to 54 years, respectively; the corresponding ratios for women were 1.48, 2.22, and 2.79. Age and male sex were significant risk factors, whereas insulin use, diabetes duration, smoking, body mass index, and area of residence were not. Diabetes duration became a significant factor after excluding patients who died of NHL within 5 years of diabetes diagnosis. Patients with diabetes have a higher risk of mortality from NHL, but insulin use is not associated with NHL mortality. Future studies are needed to fully elucidate any association between increased mortality rate ratio and younger age as well as the lack of association between NHL and insulin use demonstrated herein. © 2012 Elsevier Inc.

Chan J.C.C.,National Taiwan University
Topics in Current Chemistry | Year: 2012

This review discusses the solid-state NMR techniques developed for the study of amyloid fibrils. Literature up to the end of 2010 has been surveyed and the materials are organized according to five categories, viz. homonuclear dipolar recoupling and polarization transfer via J-coupling, heteronuclear dipolar recoupling, correlation spectroscopy, recoupling of chemical shift anisotropy, and tensor correlation. Our emphasis is on the NMR techniques and their practical aspects. The biological implications of the results obtained for amyloid fibrils are only briefly discussed. Our main objective is to showcase the power of NMR in the study of biological unoriented solids. © 2011 Springer-Verlag Berlin Heidelberg.

Chen F.,National Taiwan University
Renewable and Sustainable Energy Reviews | Year: 2010

As a country lacking energy reserves, Taiwan imports 99.2% of its energy, with only a small portion of indigenous energy, such as hydro, wind, and solar. In 2008, each Taiwanese spent 85,000 NTD dollars (1 USD ∼ 32 NTD) to purchase oil, coal, gas, and nuclear fuel from foreign countries, accounting for a total payment of 1.8 trillion NTD, more than the annual budget of the Taiwan government of 1.7 trillion NTD. In the same year, Taiwan emitted about 1% of the world's greenhouse gas (GHG), or 12 tons per person-year, ranking 18th globally. These situations in terms of energy security and carbon emission are very severe. To resolve these severe situations, harnessing the power of the Kuroshio in eastern Taiwan offers a great opportunity. The Kuroshio is a branch of the North Pacific Ocean current. Due to the westward-enhanced effect, this ocean current is strong and stable as it passes through eastern Taiwan. The flow rate is about 30 sverdrup (Sv) or 1000 times that of the Yangtze River, the average speed is 1 m/s, the flow direction is fixed to the north, and the flow path is close to the east coast of Taiwan. By precisely locating high-quality sites and implementing sequential works with careful planning, one can possibly generate exploitable power more than 30 GW. With 30 GW of clean energy, Taiwan could effectively enhance energy security, reduce GHG emission, and lower energy-purchasing cost. This paper proposes a feasibility study to explore the power of the Kuroshio. The content consists of four parts: (1) assessment of Kuroshio power reserves, (2) development of turbine generators, (3) development of turbine-anchor system, and (4) deep-sea marine engineering of turbine clusters. By integrating these technologies above, we propose a project to construct a 30 MW pilot plant. In this project, we also discuss the financial analysis and propose new regulations, environmental impact analysis, risk assessment, and other relevant issues. © 2010 Elsevier Ltd. All rights reserved.

Chi Y.,National Tsing Hua University | Chou P.-T.,National Taiwan University
Chemical Society Reviews | Year: 2010

One goal of this critical review is to provide advanced methodologies for systematic preparation of transition-metal based phosphors that show latent applications in the field of organic light emitting diodes (OLEDs). We are therefore reviewing various types of cyclometalating chelates for which the favorable metal-chelate bonding interaction, on the one hand, makes the resulting phosphorescent complexes highly emissive in both fluid and solid states at room temperature. On the other hand, fine adjustment of ligand-centered π-π* electronic transitions allows tuning of emission wavelength across the whole visible spectrum. The cyclometalating chelates are then classified according to types of cyclometalating groups, i.e. either aromatic C-H or azolic N-H fragment, and the adjacent donor fragment involved in the formation of metallacycles; the latter is an N-containing heterocycle, N-heterocyclic (NHC) carbene fragment or even diphenylphosphino group. These cyclometalating ligands are capable to react with heavy transition-metal elements, namely: Ru(ii), Os(ii), Ir(iii) and Pt(ii), to afford a variety of highly emissive phosphors, for which the photophysical properties as a function of chelate or metal characteristics are systematically discussed. Using Ir(iii) complexes as examples, the C^N chelates possessing both C-H site and N-heterocyclic donor group are essential for obtaining phosphors with emission ranging from sky-blue to saturated red, while the N^N chelates such as 2-pyridyl-C-linked azolates are found useful for serving as true-blue chromophores due to their increased ligand-centered π-π* energy gap. Lastly, the remaining NHC carbene and benzyl phosphine chelates are highly desirable to serve as ancillary chelates in localizing the electronic transition between the metal and remaining lower energy chromophoric chelates. As for the potential opto-electronic applications, many of them exhibit remarkable performance data, which are convincing to pave a broad avenue for further development of all types of phosphorescent displays and illumination devices (94 references). © 2010 The Royal Society of Chemistry.

Ma C.-T.,National Taiwan University
Journal of High Energy Physics | Year: 2016

Abstract: Entanglement is a physical phenomenon that each state cannot be described individually. Entanglement entropy gives quantitative understanding to the entanglement. We use decomposition of the Hilbert space to discuss properties of the entanglement. Therefore, partial trace operator becomes important to define the reduced density matrix from different centers, which commutes with all elements in the Hilbert space, corresponding to different entanglement choices or different observations on entangling surface. Entanglement entropy is expected to satisfy the strong subadditivity. We discuss decomposition of the Hilbert space for the strong subadditivity and other related inequalities. The entanglement entropy with centers can be computed from the Hamitonian formulations systematically, provided that we know wavefunctional. In the Hamitonian formulation, it is easier to obtain symmetry structure. We consider massless p-form theory as an example. The massless p-form theory in (2p + 2)-dimensions has global symmetry, similar to the electric-magnetic duality, connecting centers in ground state. This defines a duality structure in centers. Because it is hard to exactly compute the entanglement entropy from partial trace operator, we propose the Lagrangian formulation from the Hamitonian formulation to compute the entanglement entropy with centers. From the Lagrangian method and saddle point approximation, the codimension two surface term (leading order) in the Einstein gravity theory or holographic entanglement entropy should correspond to non-tensor product decomposition (center is not identity). Finally, we compute the entanglement entropy of the SU(N) Yang-Mills lattice gauge theory in the fundamental representation using the strong coupling expansion in the extended lattice model to obtain spatial area term in total dimensions larger than two for N > 1. © 2016, The Author(s).

Liu C.-L.,Yamagata University | Chen W.-C.,National Taiwan University
Polymer Chemistry | Year: 2011

Organic materials for memory devices have attracted significant scientific interest recently due to the advantages of rich structure flexibility, low cost, solution processability, and three-dimensional stacking capability. This minireview highlights the recent developments in donor-acceptor polymers for resistive switching memory device applications including conjugated polymers, functional polyimides, non-conjugated pendent polymers, and polymer composites. It emphasizes the structure-memory characteristic relationship of donor-acceptor polymers for advanced memory device applications. © 2011 The Royal Society of Chemistry.

Wu C.-C.,National Taiwan University
Bulletin of the American Meteorological Society | Year: 2013

Chun-Chieh Wu shares his views on the key findings from the special issue of the journal Terrestrial, Atmospheric and Oceanic Sciences (TAO) for improving prediction of extreme rains at landfall. Key findings and consensuses in this special issue are carried out from approaches of statistics, observations, and numerical simulations. The deficiencies in the representation of the TC translation speed, the vortex intensity/structure, and its interactions with its ambient systems in the model appear to hinder the forecast/simulation of rainfall associated with Morako, while the forecast/simulated track errors are small. Numerical models with sufficiently fine resolution and sophisticated physical processes are also important and can be combined with initial atmospheric and oceanic conditions for better understanding mechanisms involved in extreme rainfall events.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Annals of Oncology | Year: 2012

Background: The association between diabetes and non-Hodgkin's lymphoma (NHL) is rarely studied and the risk associated with insulin use is not known. Materials and methods: The crude and age-standardized trends of NHL incidence in the general population from 1979 to 2007 were first calculated. NHL prevalence and annual incidence in 2005 were calculated in 329 198 insurants aged ≥45 years from a random sample of 1 000 000 insurants of the National Health Insurance. The risk factors were evaluated using logistic regression. Results: NHL incidence trends increased significantly in either sex. A total of 1079 and 148 NHL cases were identified for prevalence and incidence analyses, respectively. The respective prevalence (per 100 000) for diabetic and nondiabetic subjects was 480.2 and 269.9 (P < 0.01), and the respective incidence (per 100 000) was 70.9 and 35.3 (P < 0.01). Odds ratio for diabetic versus nondiabetic subjects after adjustment for age, sex, occupation, and living region was 1.51 (95% confidence interval 1.33-1.71) for prevalence and 1.48 (1.06-2.06) for incidence. In diabetic patients, the adjusted odds ratio for insulin users versus nonusers was 1.63 (1.23-2.15) for prevalence and 2.52 (1.37-4.64) for incidence. Conclusions: NHL incidence is increasing in Taiwan. Diabetes and insulin use are associated with a higher risk. © The Author 2011. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved.

Macrophages play a pivotal role in the immune system through recognition and elimination of microbial pathogens. Toll-like receptors (TLRs) on macrophages interact with microbial substances and initiate signal transduction through intracellular adapters. TLR4, which recognizes the lipopolysaccharides (LPS) on Gram-positive and Gram-negative bacteria, triggers downstream signaling mediators and eventually activates IκB kinase (IKK) complex and mitogen-activated protein kinases (MAPKs) such as p38. Previous reports revealed that, in addition to NF-κB, a core transcription factor of the innate immune response, the induction of some LPS-induced genes in macrophages required another transcription factor whose activity depends on p38. However, these additional transcription factors remain to be identified. In order to identify p38-activated transcription factors that cooperate with NF-κB in response to LPS stimulation, microarrays were used to identify genes regulated by both NF-κB and p38 using wild-type, IKK-depleted, and p38 inhibitor-treated mouse bone marrow-derived macrophages (BMDMs). In silico analysis of transcription factor binding sites was used to predict the potential synergistic transcription factors from the co-expressed genes. Among these genes, NF-κB and C/EBPβ, a p38 downstream transcription factor, were predicted to co-regulate genes in LPS-stimulated BMDMs. Based on the subsequent results of a chromatin immunoprecipitation assay and TNFAIP3 expression in C/EBPβ-ablated macrophages, we demonstrated that Tnfaip3 is regulated by both NF-κB and p38-dependent C/EBPβ. These results identify a novel regulatory mechanism in TLR4-mediated innate immunity.

Chern J.-L.,National Central University | Lin C.-S.,National Taiwan University
Archive for Rational Mechanics and Analysis | Year: 2010

Let Ω be a bounded smooth domain in RN, N ≧ 3 and Da1,2(Ω) be the completion of C0∞(Ω) with respect to the norm, The Caffarelli-Kohn-Nirenberg inequalities state that there is a constant C > 0 such that, We prove the best constant for (0.1), is always achieved in Da1,2(Ω)} provided that 0 ∈ ∂Ω and the mean curvature H(0) < 0, where a, b satisfies If a = 0 and 1 > b > 0, then the result was proved by Ghoussoub and Robert [12]. © 2009 Springer-Verlag.

Liu C.-S.,National Taiwan University
Numerical Heat Transfer, Part B: Fundamentals | Year: 2014

The left-boundary data of temperature and heat flux are used to estimate an unknown heat conductivity function in a nonlinear heat conduction equation. A Lie-group adaptive method (LGAM) is developed to derive a Lie-group equation defined at two different times, which can be used to recover a spatial-dependence heat conductivity function through a few iterations. Also, the one-dimensional Calderón inverse problem is addressed by applying the present methodology to recover a steady-state heat conductivity coefficient in terms of space variable. The convergence speed and accuracy of the present LGAM are examined by linear and nonlinear numerical examples under noisy input data. © 2014 Copyright Taylor and Francis Group, LLC.

Wu C.-Y.,Far Eastern Memorial Hospital | Tsai Y.-P.,National Yang Ming University | Wu M.-Z.,National Yang Ming University | Teng S.-C.,National Taiwan University | Wu K.-J.,National Yang Ming University
Trends in Genetics | Year: 2012

The epithelial-mesenchymal transition (EMT) is a developmental process that is important for organ development, metastasis, cancer stemness, and organ fibrosis. The EMT process is regulated by different signaling pathways as well as by various epigenetic and post-transcriptional mechanisms. Here, we review recent progress describing the role of different chromatin modifiers in various signaling events leading to EMT, including hypoxia, transforming growth factor (TGF)-β, Notch, and Wnt. We also discuss post-transcriptional mechanisms, such as RNA alternative splicing and the effects of miRNAs in EMT regulation. Furthermore, we highlight on-going and future work aimed at a detailed understanding of the epigenetic and post-transcriptional mechanisms that regulate EMT. This work will shed new light on the cellular and tumorigenic processes affected by EMT misregulation. © 2012 Elsevier Ltd.

Okuyama T.,National Taiwan University
Biological Control | Year: 2012

Functional response is an important determinant of community dynamics, and thus empirical methods for characterizing functional responses are as important in understanding ecological processes. The most commonly used method is based on the sum of squares, and the maximum likelihood method is rarely used. When the likelihood method is used, potentially inappropriate probability distributions such as binomial distributions are typically assumed for the number of prey eaten in experiments. In this study, I present a likelihood approach in which the probability distributions are generated by mechanistic understanding of predation processes using Monte Carlo simulations. An example is given on the Holling type II functional response model, but the method is flexible and allows characterization of a wide variety of functional response models. In the example, the likelihood method consistently resulted in superior estimates than the least squares method. © 2011 Elsevier Inc.

Liu T.,MediaTek Inc. | Liao W.,National Taiwan University
IEEE Transactions on Wireless Communications | Year: 2010

In this paper, we tackle the multicast problem with the consideration of the interference between multicast trees in multi-radio multi-channel wireless mesh networks (MR-MC WMNs). We consider a dynamic traffic model, i.e., multicast session requests arrive dynamically without any prior knowledge of future requests. Each node in the network acts as a Transit Access Point (TAP), and has one or multiple radios tuned to non-overlapping channels. We prove that in MRMC WMNs, the minimum cost multicast tree (MCMT) problem, i.e., finding the multicast tree with minimum transmission cost, is NP-hard. We then formulate the problem by an Integer Linear Programming (ILP) model to solve it optimally, and propose a polynomial-time near-optimal algorithm, called Wireless Closest Terminal Branching (WCTB), for the MCMT problem. To alleviate the interference between multicast trees (sessions), we present a polynomial-time algorithm that computes the minimum interference minimum cost path in MR-MC WMNs, and integrate it into WCTB without altering the performance bound of WCTB on the tree cost. The experimental study shows that the tree cost produced by WCTB is very close to the optimal and that the proposed algorithm for interference alleviation is effective. To the best of our knowledge, this is the first paper that studies the MCMT problem in MR-MC WMNs. © 2010 IEEE.

Fang S.-H.,Yuan Ze University | Lin T.-N.,National Taiwan University
IEEE Transactions on Wireless Communications | Year: 2010

Recent advances in mobile devices and ubiquity of wireless infrastructures create the opportunity to utilize heterogeneous wireless networks (HWNs) for localization. To efficiently exploit the spatial correlation embedded in the measurements from HWNs, we proposed two algorithms via a cooperative approach, called Direct Multi-Radio Fusion and Cooperative Eigen- Radio Positioning. The former discovers the spatial correlation after the information of measurements is reorganized to minimize the redundancy. The latter takes a further step to incorporate the spatial discrimination to estimate the location. We have implemented our algorithms for different wireless technologies involving the cellular GSM, DVB, FM and WLAN in realistic outdoor/indoor environments. The results show that the proposed algorithm reduces 44.19-48.88% of the mean error, as compared to the conventional approaches. © 2006 IEEE.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Annals of Medicine | Year: 2011

Background. To evaluate the trend of prostate cancer mortality in Taiwanese general population and the association between diabetes and prostate cancer mortality. Materials and methods. In the general population during 19952006, the trends of prostate cancer mortality were evaluated, followed by calculation of age-specific mortality rates for age 4064, 6574, and ≥ 75 years. A cohort of 102,651 diabetic men aged ≥ 40 years recruited in 19951998 was followed prospectively. Results. The trends of crude and age-standardized mortality from prostate cancer in the general population increased significantly (P < 0.0001). In the general population, 7,966 men aged ≥ 40 years died of prostate cancer, and aging was associated with increased risk. Age-specific prostate cancer mortality suggested significantly increasing trend for ages 6574 and ≥ 75 years. A total of 321 diabetic men died of prostate cancer (crude mortality rate 41.9/100,000 person-years). Mortality rate ratios (95% confidence interval) showed higher risk of prostate cancer mortality in the diabetic patients, with magnitude increased with decreasing age: 1.55 (1.291.86), 2.68 (2.293.13), and 6.84 (5.348.75) for age ≥ 75, 6574, and 4064 years, respectively. Conclusions. Prostate cancer mortality in the Taiwanese general population is increasing. Diabetic patients have a higher risk of prostate cancer mortality, which is more remarkable with decreasing age. © 2011 Informa UK, Ltd.

Lin S.-C.,Georgia Institute of Technology | Chen K.-C.,National Taiwan University
IEEE Transactions on Wireless Communications | Year: 2014

To alleviate the spectrum shortage for sensor networks with tremendous sensors, cognitive radio technology enabling multi-hop opportunistic networking and concurrent transmissions overlaying the primary system suggests an attractive facilitation of large-scale wireless sensor networks (WSNs) and machine-to-machine communications. However, subsequent significant end-to-end delay in large WSN can prohibit practical applications. Leveraging the nature of traffic in sensor networks, we develop in-network computation to reduce requisite transmissions and to accommodate more concurrent transmissions under a given spectrum. Specifically, distributed source coding and broadcasting in wireless communication are exploited to build the computational framework and the achievable network capacity is examined. Furthermore, a greedy networking algorithm is adopted to justify significant improvement on end-to-end delay and further statistical QoS guarantee, while yielding considerable system throughput gain for practical deployment of WSNs. Performance evaluations confirm that we successfully demonstrate communication efficiency from in-network computations and facilitate a new paradigm for spectrum efficient cognitive radio networks, which shall be applicable in general multi-hop wireless networks and spectrum-sharing WSNs. © 2014 IEEE.

Ho P.-M.,National Taiwan University
Chinese Journal of Physics | Year: 2010

We give a concise review of recent developments of the M5-brane theory derived from the Bagger-Lambert model. It is a 6 dimensional supersymmetric self-dual gauge theory describ-ing an M5-brane in a large constant C-eld background. The non-Abelian gauge symmetry corresponds to diffeomorphisms preserving an exact 3-form on the world volume, which de-nes a Nambu-Poisson bracket. Various interesting geometric and algebraic properties of the theory are discussed. © 2010 THE PHYSICAL SOCIETY OF THE REPUBLIC OF CHINA.

Okuyama T.,National Taiwan University
Theoretical Population Biology | Year: 2011

One predator-two prey community models are studied with an emphasis on individual variation in predator behavior. The predator behaves according to a well-known prey choice model. The behavioral model predicts that predators should always attack the primary prey (more profitable prey of the two), but only attack the alternative prey (less profitable prey of the two) when the density of the primary prey is below a threshold density. The predator that accepts the alternative prey does not discriminate between the primary and alternative prey (all-or-nothing preference for the alternative prey). However, empirical studies do not result in clear all-or-nothing responses. Previous models examined the relaxation of the all-or-nothing response by assuming partial preference (e.g., predators preferentially forage on the primary prey even when they also attack the alternative prey). In this study, I consider individual variation in two predator traits (prey density perception and handling time) as the sources of the variation in the threshold density, which can make empirical data appear deviated from the expectation. I examine how community models with partial preference and individual variation differ in their dynamics and show that the differences can be substantial. For example, the dynamics of a model based on individual variation can be more stable (e.g., stable in a wider parameter region) than that of a model based on partial preference. As the general statistical property (Jensen's inequality) is a main factor that causes the differences, the results of the study have general implications to the interpretation of models based on average per-capita rates. © 2011 Elsevier Inc.

Okazaki T.,National Taiwan University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We study the energy representation of conformal quantum mechanics as the Whittaker vector without specifying the classical Lagrangian. We show that a generating function of expectation values among two excited states of the dilatation operator in conformal quantum mechanics is a solution to the Wheeler-DeWitt equation and it corresponds to the AdS2 partition function evaluated as the minisuperspace wave function in Liouville field theory. We also show that the dilatation expectation values in conformal quantum mechanics lead to the asymptotic smoothed counting function of the Riemann zeros. © 2015 American Physical Society.

Hu C.D.,National Taiwan University
Journal of Physics Condensed Matter | Year: 2012

The DzyaloshinskiiMoriya (DM) interaction in metals is an important mechanism for many magnetic properties. We start with the sd exchange model and spinorbit interaction for weak itinerant ferromagnetic systems to establish the form of DM interaction for metallic magnetic systems. The sd exchange interaction is treated accurately and the conduction electron-mediated magnetism gives a form of DM interaction which is different from that in insulators. The implications of our result to spiral spin states and skyrmion lattices are also discussed. © 2012 IOP Publishing Ltd.

Ma C.-T.,National Taiwan University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We combine symmetry structures of ordinary (parallel directions) and dual (transversal directions) coordinates to construct the Dirac-Born-Infeld theory. The ordinary coordinates are associated with the Neumann boundary conditions and the dual coordinates are associated with the Dirichlet boundary conditions. Gauge fields become scalar fields by exchanging the ordinary and dual coordinates. A gauge transformation of a generalized metric is governed by the generalized Lie derivative. The gauge transformation of the massless closed string theory gives the C-bracket, but the gauge transformation of the open string theory gives the F-bracket. The F-bracket with the strong constraints is different from the Courant bracket by an exact one-form. This exact one-form should come from the one-form gauge field. Based on a symmetry point of view, we deduce a suitable action with a nonzero H-flux at the low-energy level. From an equation of motion of the scalar dilaton, it defines a generalized scalar curvature. Finally, we construct a double sigma model with a boundary term and show that this model with constraints is classically equivalent to the ordinary sigma model. © 2015 American Physical Society.

He X.-G.,Shanghai JiaoTong University | He X.-G.,National Taiwan University | Zee A.,University of California at Santa Barbara
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We explore some ways of minimally modifying the neutrino mixing matrix from tribimaximal, characterized by introducing at most one mixing angle and a CP violating phase thus extending our earlier work. One minimal modification, motivated to some extent by group theoretic considerations, is a simple case with the elements Vα2 of the second column in the mixing matrix equal to 1/√3. Modifications by keeping one of the columns or one of the rows unchanged from tribimaximal mixing all belong to the class of minimal modification. Some of the cases have interesting experimentally testable consequences. In particular, the T2K and MINOS collaborations have recently reported indications of a nonzero θ13. For the cases we consider, the new data sharply constrain the CP violating phase angle δ, with δ close to 0 (in some cases) and π disfavored. © 2011 American Physical Society.

Pelanti M.,ENSTA ParisTech | Shyue K.-M.,National Taiwan University
Journal of Computational Physics | Year: 2014

We model liquid-gas flows with cavitation by a variant of the six-equation single-velocity two-phase model with stiff mechanical relaxation of Saurel-Petitpas-Berry (Saurel et al., 2009) [9]. In our approach we employ phasic total energy equations instead of the phasic internal energy equations of the classical six-equation system. This alternative formulation allows us to easily design a simple numerical method that ensures consistency with mixture total energy conservation at the discrete level and agreement of the relaxed pressure at equilibrium with the correct mixture equation of state. Temperature and Gibbs free energy exchange terms are included in the equations as relaxation terms to model heat and mass transfer and hence liquid-vapor transition. The algorithm uses a high-resolution wave propagation method for the numerical approximation of the homogeneous hyperbolic portion of the model. In two dimensions a fully-discretized scheme based on a hybrid HLLC/Roe Riemann solver is employed. Thermo-chemical terms are handled numerically via a stiff relaxation solver that forces thermodynamic equilibrium at liquid-vapor interfaces under metastable conditions. We present numerical results of sample tests in one and two space dimensions that show the ability of the proposed model to describe cavitation mechanisms and evaporation wave dynamics. © 2013 Elsevier Inc.

Lu L.,National Taiwan University
International Journal of Aging and Human Development | Year: 2010

The aim of this research was twofold: to examine the prevalence of employment and under-employment among Taiwanese older workers (aged 50 and above), and to explore personal correlates of their employment status, in particular gender and education. Using a national representative sample, we found that: 1) a rather substantial percentage of people continued to work well into their older years; 2) the underemployment rates were substantial in the older age, and less-educated workers and women were more at risk; and 3) multivariate analysis confirmed that age, gender, personal health, spousal health, and family income were significant predictors of continued employment after age 50. Gender and education were also significantly related to the risk of under-employment. Our results highlight the importance and urgency of more concerted research to inform public labor policies, especially in an aging developing society where older workers are faced with a double challenge of economic and societal restructuring.

He X.-G.,Shanghai JiaoTong University | He X.-G.,National Taiwan University | Tandean J.,National Central University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

Recent LHC searches have not found a clear signal of the Higgs boson h of the standard model (SM) with three or four families in the mass range m h=120-600GeV. If the Higgs had an unexpectedly large invisible branching ratio, the excluded mh regions would shrink. This can be realized in the simplest weakly interacting massive particle dark matter (DM) model, which is the SM plus a real gauge-singlet scalar field D as the DM, via the invisible mode h→DD. Current data allow this decay to occur for D-mass values near, but below, mh/2 and those compatible with the light DM hypothesis. For such D masses, h→DD can dominate the Higgs width depending on mh, and thus sizable portions of the mh exclusion zones in the SM with three or four families may be recovered. Increased luminosity at the LHC may even reveal a Higgs having SM-like visible decays still hiding in the presently disallowed regions. The model also accommodates well the new possible DM hints from CRESST-II and will be further tested by improved data from future DM direct searches. © 2011 American Physical Society.

Yueh H.-P.,National Taiwan University
International Journal of Engineering Education | Year: 2013

Engineering education has been striving to find good ways to improve students' learning of engineering. However, nontechnical professional skills such as communication and interpersonal skills, teamwork, and creative and intuitive thinking skills are also seen as essential for engineers, and especially for leaders. The portfolio practice has proved to be effective in supporting students' learning, as it allows them to document evidence of their learning and to reflect on personal growth. This paper reports a case study on implementation of the portfolio practice in an engineering leadership block curriculum and assessment of students' perceptions of this practice. It also provides implications for advancing engineering education with this approach. © 2013 TEMPUS Publications.

Chen B.,Peking University | Jahn B.-M.,National Taiwan University | Suzuki K.,Japan Agency for Marin Earth Science and Technology
Geology | Year: 2013

The Mesozoic high-Mg dioritic rocks in the North China Craton have been suggested to be part of adakitic rocks. The origin of the high-Mg diorites has been attributed to equilibration of partial melts from delaminated mafi c crust (eclogite) with mantle peridotite. Here we present petrological and Os isotopic data against the delamination model, and propose a process of magma mixing between siliceous crustal melts and basaltic magma from metasomatized mantle in a post-kinematic setting for their origin. The magma mixing process is supported by (1) euhedral overgrowths of high-Ca plagioclase and high-Mg pyroxene over low-Ca plagioclase and low-Mg pyroxene, respectively, and (2) highly radiogenic Os isotopic compositions, and negatively correlated Nd and Sr isotopic ratios. Our proposed model is probably applicable to the general mode of origin and tectonic settings of high-Mg adakitic magmas. © 2012 Geological Society of America.

This work re-examines the potential flow theory for a sphere in normal approach to a wall, based on the classical results derived by Lamb [Hydrodynamics (Dover, New York, 1932)] and Milne-Thomson [Theoretical Hydrodynamics, 5th ed. (Dover, New York, 1968)]. These authors generated an expression in which the kinetic energy for a sphere in an unbounded fluid is augmented by a wall correction function in terms of an infinite series that depends on the scaled center-to-wall distance, h *=h/a, with a denoting the sphere radius. By truncating the series at the order of h *-3, the resulting one-term correction function, 3/8h *-3, is widely employed to approximate the wall-amplified added mass coefficient, C AM(h *), in multiphase flow research. Nonetheless, this work shows that this one-term correction deviates greatly from corrections including higher order terms when the interstitial gap drops below the half sphere radius. Thus, an explicit formula is developed, for all h *, using a near-wall Padé approximation, an intermediate bridging function, and a far-field approximation. This proposed formula provides an efficient and reasonable approximation to the infinite series and thus may serve as an improved wall correction function as compared to the one-term formula. The developed formula is applied to compute the unsteady approach of a nonrotating sphere toward a wall in a viscous fluid at low Reynolds number condition. In addition to Brenner's wall correction on the quasisteady viscous force [H. Brenner, "The slow motion of a sphere through a viscous fluid towards a plane surface," Chem. Eng. Sci.16, 242 (1961)], the current formula is employed to modify both the added mass coefficient, from 1/2, and the history force. This latter force is modified by integrating the wall-modified potential flow theory with the boundary layer theory. If the one-term correction is used in the equation of motion, underestimation of the sphere motion and the force magnitudes are observed. Lastly, the limiting value of the infinite series derived by Lamb and Milne-Thomson as h→a is analytically evaluated, leading to a result in terms of the generalized zeta function, ζ(3,1). When this limiting value is compared to the one-term correction at h=a, a 38% deficiency of the wall-augmented kinetic energy is revealed, resulting in an underestimated C AM(h *) that plays a crucial role in presenting the near-wall normal approach. © 2010 American Institute of Physics.

Chen C.K.-M.,Academia Sinica, Taiwan | Chan N.-L.,National Taiwan University | Wang A.H.-J.,Academia Sinica, Taiwan
Trends in Biochemical Sciences | Year: 2011

The β-propeller is a highly symmetrical structure with 4-10 repeats of a four-stranded antiparallel β-sheet motif. Although β-propeller proteins with different blade numbers all adopt disc-like shapes, they are involved in a diverse set of functions, and defects in this family of proteins have been associated with human diseases. However, it has remained ambiguous how variations in blade number could alter the function of β-propellers. In addition to the regularly arranged β-propeller topology, a recently discovered β-pinwheel propeller has been found. Here, we review the structural and functional diversity of β-propeller proteins, including β-pinwheels, as well as recent advances in the typical and atypical propeller structures. © 2011 Elsevier Ltd.

Su L.-H.,Far Eastern Memorial Hospital | Chen T.H.-H.,National Taiwan University
British Journal of Dermatology | Year: 2010

Background Several previous studies have investigated the association between factors related to metabolic syndrome, which is known to increase the risk of type 2 diabetes mellitus and cardiovascular disease, and androgenetic alopecia (AGA). However, the results of these studies have been inconsistent. Objectives To determine if there is an association between metabolic syndrome and AGA after adjustment for potential confounders. Methods A population-based cross-sectional survey was conducted in Tainan, Taiwan. A total of 740 subjects aged 40-91 years participated in the survey between April and June 2005. The Norwood classification was used to assess the degree of hair loss. Information on components of metabolic syndrome together with other possible risk factors was collected. Results A statistically significant association was found between AGA and the presence of metabolic syndrome [odds ratio (OR) 1·67, 95% confidence interval (CI) 1·01-2·74] as well as between AGA and the number of fulfilled metabolic syndrome components (OR 1·21, 95% CI 1·03-1·42) after controlling for age, family history of AGA and smoking status. Among metabolic syndrome components, high-density lipoprotein cholesterol (HDL-C) (OR 2·36, 95% CI 1·41-3·95; P = 0·001) was revealed as the most important factor associated with AGA. Conclusions Our population-based study found a significant association between AGA and metabolic syndrome; among the components of metabolic syndrome, HDL-C was found to be of particular importance. This finding may have significant implications for the identification of metabolic syndrome in patients with moderate or severe AGA. Early intervention for metabolic syndrome is critical to reduce the risk and complications of cardiovascular disease and type 2 diabetes mellitus later in life. © 2010 British Association of Dermatologists.

Yang H.-H.,National Taiwan University
Computers and Industrial Engineering | Year: 2010

The purpose of this paper is to estimate the efficiencies of, and to discuss the managerial implications for 12 international airports in the Asia-Pacific region based on data from the period 1998-2006. We applied data envelopment analysis (DEA) and stochastic frontier analysis (SFA) to compute efficiency estimates, and the empirical results are discussed in terms of management perspectives and mathematical analysis. From the management perspectives, we suggest that airports should focus more on investment than on human resources. In addition, we found that inefficiency effects associated with the production functions of airports increased over the investigated period. From the perspective of mathematical analysis, we determined that deviations from the efficient frontiers of production functions are largely attributed to technical inefficiency. Finally, the empirical results imply that employing the discretion to adjust the scale size of the production function appears to improve efficiency. The main contribution of the paper is in showing how DEA and SFA can be used together to complement each other. © 2010 Elsevier Ltd. All rights reserved.

Guan B.T.,National Taiwan University
Agricultural and Forest Meteorology | Year: 2014

Numerous studies conducted over the past decade have revealed that plant phenophases have shifted in many temperate ecosystems. Although the consensus is that these shifts reflect plant responses to rise in temperatures, we have yet to match unequivocally the phenological and temperature trends. More importantly, little is known about warming's effects on and contributions to phenophase variability. The key to accomplishing both tasks lies in a proper separation of a trend from natural variability. Based on ensemble empirical mode decomposition, this study shows that, over the past 30 years, the advancing trends in the first flowering dates (FFD) of apple ( Malus domestica) in Austria and blackthorn ( Prunus spinosa) in Germany unequivocally correspond to the respective regional winter/spring warming trends. The variability of both FFD series before 1981 was almost entirely due to natural variability. In contrast, warming since 1981 contributed 4% and 21% toward the total phenophase variability of apple and blackthorn, respectively. Furthermore, while contributing to both the temperature and FFD overall variability, recent warming also lowers the FFD natural variability by modulating the temperature natural oscillation amplitudes. Thus, warming can affect both the timing and the natural variability of a phenophase development. As concurrently shifting the timings and reducing the natural variability of phenophase developments may have important ecological and evolutionary consequences, it will be of great interest and importance to examine whether the conclusion holds for other phenophases and species in various regions as well. The introduced approach will be a valuable tool for answering the question. © 2014 Elsevier B.V.

Yang T.C.,National Taiwan University
The International journal of oral & maxillofacial implants | Year: 2013

To evaluate the biomechanical effects of platform switching on external- and internal-connection implants with regard to strain around the implants under loading. Implant analogs (5.0 × 12 mm) with external (EX) and internal (IN) connections were embedded into an acrylic resin block that simulated an edentulous ridge. Abutments with diameters of 5.0, 4.2, and 3.7 mm were attached to EX and IN analogs. A 100-N lateral load was applied to each abutment at an angle of 30 degrees, and the experiments were repeated 10 times. Strain gauges were attached to the implant surface at 1 mm (neck area) and 8 mm (apex area) below the platform to measure the strain around the implant under loading. Statistical analyses were performed by one-way analysis of variance and Steel-Dwass test. P < .05 was considered statistically significant. Significantly higher strain values were found around the neck area in both analogs (EX, -682.8 Με; IN,-582.1 Με) with conventional matching 5-mm-diameter abutments, followed by the analogs with 4.2-mm-diameter (EX, -184.1 Με; IN, -229.1 Με) and 3.7-mm-diameter (EX, -150.5 Με; IN, -129.7 Με) platform-switched abutments; this was statistically significant for EX (P < .05). In the apex area, a mild increase in strain was found with a decrease in abutment diameter, but no significant difference was found between 4.2- and 3.7-mm-diameter abutments for IN (P > .05). Within the limitations of this study, platform switching reduced strain surrounding the implant neck area in both EX and IN during loading. However, the decreases in strain values were greater with EX than with IN.

Distinct microRNA (miRNA) and mRNA signatures were reported in nucleophosmin (NPM1)-mutated acute myeloid leukemia (AML). However, it remains unknown whether the mutation participates in the dynamic interaction between miRNA and mRNA. In this study, we aimed to investigate the role of NPM1 mutation in modulating miRNA–mRNA regulation (MMR). From the sample-paired miRNA/mRNA microarrays of 181 de novo AML patients, we found that MMR was dynamic and could be affected by NPM1 mutation. By a systematic framework, we identified 493 NPM1 mutation-modulated MMR pairs, where the strength of MMR was significantly attenuated in patients carrying NPM1 mutations, compared to those with wild-type NPM1. These miRNAs/mRNAs were associated with pathways implicated in cancer and known functions of NPM1 mutation. Such modulation of MMR was validated in two independent cohorts as well as in cells with different NPM1 mutant burdens. Furthermore, we showed that the regulatory strength of nine MMR pairs could predict patients’ outcomes. Combining these pairs, a scoring system was proposed and shown to predict survival in discovery and validation data sets, independent of other known prognostic factors. Our study provides novel biological insights into the role of NPM1 mutation as a modulator of MMR, based on which a novel prognostic marker is proposed in AML.Leukemia advance online publication, 6 October 2015; doi:10.1038/leu.2015.253. © 2015 Macmillan Publishers Limited

Chern R.-L.,National Taiwan University
Journal of Physics D: Applied Physics | Year: 2013

The anomalous dispersion in pseudochiral media is theoretically investigated, with emphasis on the features of negative refraction and backward wave. In these media, material properties are characterized by symmetric magnetoelectric tensors with zero diagonal elements. Strong magnetoelectric couplings in such media give rise to a special form of petal-like dispersion curves, which support negative refraction and backward wave over a certain range of the angle of incidence. Two threshold angles in terms of the chirality parameter are given to characterize these features. © 2013 IOP Publishing Ltd.

Liu C.-S.,National Taiwan University
International Journal of Solids and Structures | Year: 2013

In this paper we develop a generalized Hamiltonian formulation of a perfectly elastoplastic model, which is a typical dissipative system. On the cotangent bundle of the yield manifold, a Lie-Poisson bracket is used to construct the differential equations system. The stress trajectory is a coadjoint orbit on the Poisson manifold under a coadjoint action by the Lie-group SO(n). The plastic differential equation is an affine non-linear system, of which a finite-dimensional Lie algebra can be constructed, and the superposition principle is available for this system. Accordingly, we can construct numerical schemes to automatically preserve the yield-surface for perfect plasticity, for isotropic hardening material, as well as for an anisotropic elastic-plastic model. Then, we describe an anisotropic elastic-plastic material model without entering the work-hardening range and deforming under a specified dissipation rate, which can be achieved through a stress-dependent feedback control law of strain rate. © 2013 Elsevier Ltd. All rights reserved.

We recover an unknown space-time-dependent force in an Euler-Bernoulli beam vibration equation by an effective combination of the Lie-group adaptive method (LGAM) and the differential quadrature method (DQM). The layer-stripping technique is used to simplify this identification problem. The DQM is a feasible tool to semi-discretize the Euler-Bernoulli beam equation into a system of ordinary differential equations (ODEs) in time. Then, we can develop a two-point Lie-group equation to recover the unknown force through a few iterations. The success of the present method hinges on a rationale that the local in time ODEs and the global in time algebraic Lie-group equation have to be self-adapted during the iteration processes. The feasibility, accuracy and efficiency of the present method are assessed by comparing the estimated results with some exact solutions. © 2012 Springer-Verlag.

Hsiao H.-M.,National Taiwan University
International Journal of Fracture | Year: 2012

Interleaved toughening is a promising approach of improving fracture toughness in composites. Past observations of toughened particles have been conducted using the Optical Microscopy or Scanning Electron Microscopy for localized microstructures at a specific location; however, these methods may not be able to provide a 3-D, birds-eye view of the global particle distribution on a composite interlaminar surface. In this paper, we discovered an interesting optical phenomenon which can be used to observe surface morphology in toughened composites. This novel optical technique is able to reveal the detailed morphological information of toughened particles and individual fibers, including particle distribution uniformity, particle size variation, and fiber misalignment. It was found that particle distribution uniformity is a critical factor in differentiating the high and low Compression-After-Impact (CAI) laminates. High-CAI laminate had uniform and denser particle distribution, whereas low-CAI laminate had very non-uniform particle distribution. © Springer Science+Business Media B.V. 2012.

Liu C.-S.,National Taiwan University
Engineering Analysis with Boundary Elements | Year: 2012

For the method of fundamental solutions (MFS), a trial solution is expressed as a linear combination of fundamental solutions. However, the accuracy of MFS is heavily dependent on the distribution of source points. Two distributions of source points are frequently adopted: one on a circle with a radius R, and another along an offset D to the boundary, where R and D are problem dependent constants. In the present paper, we propose a new method to choose the best source points, by using the MFS with multiple lengths R k for the distribution of source points, which are solved from an uncoupled system of nonlinear algebraic equations. Based on the concept of equilibrated matrix, the multiple-length R k is fully determined by the collocated points and a parameter R or D, such that the condition number of the multiple-length MFS (MLMFS) can be reduced smaller than that of the original MFS. This new technique significantly improves the accuracy of the numerical solution in several orders than the MFS with the distribution of source points using R or D. Some numerical tests for the Laplace equation confirm that the MLMFS has a good efficiency and accuracy, and the computational cost is rather cheap. © 2012 Elsevier Ltd. All rights reserved.

Ouimet W.B.,Amherst College | Cook K.L.,National Taiwan University
Tectonics | Year: 2010

The orogen-scale morphology of the central Andes, which are longitudinally symmetric at ∼19°S, correlates with the modern geometry of the subducting Nazca slab but is largely independent of local bedrock geology or precipitation. Crustal thickness, as measured by the cross-strike width of the orogen above 3000 m and the cross-sectional area of the crust, is not well correlated with observed magnitudes of upper crustal shortening. In our interpretation, the large-scale morphology is instead correlated with and controlled by lithosphericscale processes and subduction dynamics. Using a semianalytic, three-dimensional Newtonian viscous flow model, we produce Andean-like topography and distribution of upper crustal shortening during subduction of an oceanic lithosphere eastward beneath the Andes provided that (1) the more steeply dipping slab segment beneath the central Andes is overlain by the weak lower or middle crust, (2) the flat slab subduction segments to the north and south of this zone are overlain by the strong middle and lower crust, and (3) the steeply dipping central slab segment is overlain by a narrow, centrally localized zone of increased crustal shortening. The resulting model orogen displays substantial orogen-parallel flow in the weak lower crust above the steep slab zone. Orogen-parallel flow does not penetrate into the regions of stronger lower crust above the flat slab segments, resulting in a broad, plateau-topped orogen above the central slab segment and narrow but high orogenic segments above the flat slab region. Redistribution of material through lower crust flow can account for the observed mismatch between crustal volume and upper crustal shortening in the central Andes and may explain young (<10 Ma) crustal thickening and surface uplift that has been argued for in some regions. © 2010 by the American Geophysical Union.

Kohda M.,National Taiwan University | Sugiyama H.,University of Toyama | Tsumura K.,Nagoya University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We investigate a model in which tiny neutrino masses are generated at the two-loop level by using scalar leptoquark and diquark multiplets. The diquark can be singly produced at the LHC, and it can decay into a pair of leptoquarks through the lepton number violating interaction. Subsequent decays of the two leptoquarks can provide a clear signature of the lepton number violation, namely two QCD jets and a pair of same-signed charged leptons without missing energy. We show that the signal process is not suppressed while neutrino masses are appropriately suppressed. © 2012 Elsevier B.V.

Kagami M.,Toho University | Miki T.,National Taiwan University | Takimoto G.,Toho University
Frontiers in Microbiology | Year: 2014

Parasites are ecologically significant in various ecosystems through their role in shaping food web structure, facilitating energy transfer, and controlling disease. Here in this review, we mainly focus on parasitic chytrids, the dominant parasites in aquatic ecosystems, and explain their roles in aquatic food webs, particularly as prey for zooplankton. Chytrids have a free-living zoosporic stage, during which they actively search for new hosts. Zoospores are excellent food for zooplankton in terms of size, shape, and nutritional quality. In the field, densities of chytrids can be high, ranging from 101 to 109 spores L-1. When large inedible phytoplankton species are infected by chytrids, nutrients within host cells are transferred to zooplankton via the zoospores of parasitic chytrids. This new pathway, the "mycoloop," may play an important role in shaping aquatic ecosystems, by altering sinking fluxes or determining system stability. The grazing of zoospores by zooplankton may also suppress outbreaks of parasitic chytrids. A food web model demonstrated that the contribution of the mycoloop to zooplankton production increased with nutrient availability and was also dependent on the stability of the system. Further studies with advanced molecular tools are likely to discover greater chytrid diversity and evidence of additional mycoloops in lakes and oceans. © 2014 Kagami, Miki and Takimoto.

Lai C.-C.,National University of Kaohsiung | Tsai C.-C.,National Taiwan University
IEEE Transactions on Instrumentation and Measurement | Year: 2010

The main objective of developing an image-watermarking technique is to satisfy both imperceptibility and robustness requirements. To achieve this objective, a hybrid image-watermarking scheme based on discrete wavelet transform (DWT) and singular value decomposition (SVD) is proposed in this paper. In our approach, the watermark is not embedded directly on the wavelet coefficients but rather than on the elements of singular values of the cover image's DWT subbands. Experimental results are provided to illustrate that the proposed approach is able to withstand a variety of image-processing attacks. © 2010 IEEE.

Luo R.C.,National Taiwan University | Chen O.,National Chung Cheng University
IEEE Transactions on Industrial Electronics | Year: 2012

Mobile sensor node deployment and power management are important issues in the wireless sensor network system. This study designs a mobile sensor node platform to achieve a highly accurate localization mechanism by using ultrasonic, dead reckoning, and radio frequency information which is processed through a particle filter algorithm. Mobile sensor node with accurate localization ability is of great interest to basic research works and applications, such as sensor deployment, coverage management, dynamic power management, etc. In this paper, we propose an efficient mobile sensor node deployment method, grid deployment, where the map is divided into multiple individual grids and the weight of each grid is determined by environmental factors such as predeployed nodes, boundaries, and obstacles. The grid with minimum values is the goal of the mobile node. We also design an asynchronous power management strategy in our sensor node to reduce power consumption of the sensor network. Several factors such as probability of event generation, battery status, coverage issues, and communication situations have also been taken into consideration. In network communication, we propose an asynchronous awakening scheme so that each node is free to switch on or off its components according to observed event statistics and make a tradeoff between communication and power consumption. The deepest sleep state period is determined by the residual power. By combining these methods, the power consumption of the sensor node can be reduced. © 2006 IEEE.

Lin C.-S.,National Taiwan University | Yan S.,University of New England of Australia
Communications in Mathematical Physics | Year: 2010

We prove the existence of bubbling solutions for the following Chern-Simons-Higgs equation: where Ω is a torus. We show that if N > 4 and p1 ≠ pj, j = 2, . . . , N, then for small ε > 0, the above problem has a solution uε, and as ε → 0, uε blows up at the vertex point p1, and satisfies This is the first result for the existence of a solution which blows up at a vertex point. © 2010 Springer-Verlag.

Hosomichi K.,National Taiwan University | Lee S.,University of Chicago
Journal of High Energy Physics | Year: 2015

Abstract: We study the system of M2-branes suspended between parallel M5-branes using ABJM model with a natural half-BPS boundary condition. For small separation between M5-branes, the worldvolume theory is shown to reduce to a 2D N = 44 super Yang-Mills theory with some similarity to q-deformed Yang-Mills theory. The gauge coupling is related to the position of the branes in an interesting manner. The theory is considerably different from the 2D theory proposed for multiple “M-strings”. We make a detailed comparison of elliptic genus of the two descriptions and find only a partial agreement. © 2015, The Author(s).

Hsiao Y.-C.,National Taiwan University | Lee W.,National Chiao Tung University
Optics Express | Year: 2013

Dual-frequency cholesteric liquid crystal (DFCLC) devices characteristically require high operation voltage, which hinders their further development in thin-film-transistor driving. Here we report on a lowervoltage switching method based on the thermodielectric effect. This technique entails applying a high-frequency voltage to occasion dielectric oscillation heating so to induce the increase in crossover frequency. The subsequent change in dielectric anisotropy of the DFCLC allows the switching, with a lower operation voltage, from the planar state to the focal conic or homeotropic state. The temperature rise incurred by the dielectric heating is described. © 2013 Optical Society of America.

Lee W.-C.,National Taiwan University
Statistics in Medicine | Year: 2011

Confounding is a major concern in observational studies. To adjust for confounding bias, the potential confounder(s) for a study must first be identified and measured. But this is not always possible. The unmeasured factors may also exhibit effect modification, and this further complicates the situation. In this paper, the author derives bounding formulas for the bias of unmeasured factors with confounding and effect-modifying potentials. Based on these formulas, the author derives two conditions (for the unmeasured factors) to explain away an observed positive finding: the low-threshold (for the minimum of two parameters related to the unmeasured factors) and the high-threshold (for the maximum) conditions. All these should help researchers make more prudent interpretations of their (potentially biased) results. © 2011 John Wiley & Sons, Ltd.

Ma C.-T.,National Taiwan University
Journal of High Energy Physics | Year: 2015

The double sigma model with the strong constraints is equivalent to a classical theory of the normal sigma model with one on-shell self-duality relation. The one-form gauge field comes from the boundary term. It is the same as the normal sigma model. The gauge symmetries under the strong constraints are the diffeomorphism and one-form gauge transformation in the double sigma model. These gauge symmetries are also the same as the Dirac-Born-Infeld (DBI) theory. The main task of this work is to compute one-loop β function to obtain the low energy effective theory of the double sigma model. We implement the self-duality relation in the action to perform the one-loop calculation. At last, we obtain the DBI theory. We also rewrite this theory in terms of the generalized metric and scalar dilaton, and define the generalized scalar curvature and tensor from the equations of motion. © 2015, The Author(s).

The Internet has become a major health information source for many patients, and they might discuss the information they get from the Internet with their doctors. I explored how the Internet as an information source influences cancer patients' communication with their doctors in Taiwan, where the doctor-patient relationship is traditionally doctor dominated. Forty-six cancer patients or families participated in seven focus group discussions. I conducted inductive analysis to examine themes emerging from discussions. Participants searched for information on the Internet to probe and verify their doctors' competence. Participants took responsibility for understanding the doctors' jargon, and the Internet helped them to do that. The Internet also helped participants spur doctors to think further about their condition, but these patients did so cautiously, with an effort not to offend doctors. The Internet as an information source did help participants talk to doctors, but the effect on changing the doctor-dominant nature of the relationship was limited. © SAGE Publications 2011.

Chang Y.-W.,National Taiwan University
Scientometrics | Year: 2013

This study uses the method of citation context analysis to compare differences in citation contexts, including cited concepts and citation functions, between natural sciences (NS) and social sciences and humanities (SSH), based on articles citing Little Science, Big Science (LSBS) published between 1963 and 2010. The findings indicate that NS and SSH researchers frequently cite LSBS as a source that is related to a specific topic and as evidence to support a claim. No significant differences were identified in the distribution of cited concepts included in LSBS, but significant differences were observed in the reasons for citing LSBS between NS and SSH citing articles. However, reverse trends were observed in the percentage of some cited concepts and citation functions between NS and SSH, which implies that subtle differences in citation behavior exist between NS and SSH researchers. In addition, each concept category has a different half-life. Concepts related to characteristics of big science and scientific collaboration have the longest half-lives. © 2013 Akadémiai Kiadó, Budapest, Hungary.

Liu K.,Academia Sinica, Taiwan | Liu K.,National Taiwan University
Annual Review of Physical Chemistry | Year: 2016

Vibrational motions of a polyatomic molecule are multifold and can be as simple as stretches or bends or as complex as concerted motions of many atoms. Different modes of excitation often possess different capacities in driving a bimolecular chemical reaction, with distinct dynamic outcomes. Reactions with vibrationally excited methane and its isotopologs serve as a benchmark for advancing our fundamental understanding of polyatomic reaction dynamics. Here, some recent progress in this area is briefly reviewed. Particular emphasis is placed on the key concepts developed from those studies. The interconnections among mode and bond selectivity, Polanyi's rules, and newly introduced vibrational-induced steric phenomena are highlighted. Copyright © 2016 by Annual Reviews. All rights reserved.

Yan S.,University of California at Berkeley | Wen J.-D.,National Taiwan University | Bustamante C.,University of California at Berkeley | Bustamante C.,Howard Hughes Medical Institute | And 2 more authors.
Cell | Year: 2015

Programmed ribosomal frameshifting produces alternative proteins from a single transcript. -1 frameshifting occurs on Escherichia coli's dnaX mRNA containing a slippery sequence AAAAAAG and peripheral mRNA structural barriers. Here, we reveal hidden aspects of the frameshifting process, including its exact location on the mRNA and its timing within the translation cycle. Mass spectrometry of translated products shows that ribosomes enter the -1 frame from not one specific codon but various codons along the slippery sequence and slip by not just -1 but also -4 or +2 nucleotides. Single-ribosome translation trajectories detect distinctive codon-scale fluctuations in ribosome-mRNA displacement across the slippery sequence, representing multiple ribosomal translocation attempts during frameshifting. Flanking mRNA structural barriers mechanically stimulate the ribosome to undergo back-and-forth translocation excursions, broadly exploring reading frames. Both experiments reveal aborted translation around mutant slippery sequences, indicating that subsequent fidelity checks on newly adopted codon position base pairings lead to either resumed translation or early termination. © 2015 Elsevier Inc.

Liu C.-S.,National Taiwan University
International Journal of Heat and Mass Transfer | Year: 2010

We consider a backward heat conduction problem (BHCP) in a slab, by subjecting to data at a final time, and some different type boundary conditions at two ends of the slab. The BHCP is known to be highly ill-posed. In order to numerically solve the BHCP we develop a new Lie-group shooting method (LGSM) in the spatial direction. It can retrieve very well the initial data with a high order accuracy. Several numerical examples of the BHCP demonstrate that the LGSM is applicable, even for those of strongly ill-posed ones with a large value of final time. Under the noisy final data the LGSM is robust against the disturbance. The new method is applicable for a severely ill-posed case with a final data very small in the order of 10-43, and the noise level is in the order of 10-1, of which the numerical solution still has an accuracy in the order of 10-2. The results are rather significant in the computations of BHCP. © 2010 Elsevier Ltd.

Lo M.-H.,University of California at Irvine | Lo M.-H.,National Taiwan University | Famiglietti J.S.,University of California at Irvine
Geophysical Research Letters | Year: 2013

Characterizing climatological and hydrological responses to agricultural irrigation continues to be an important challenge to understanding the full impact of water management on the Earth's environment and hydrological cycle. In this study, we use a global climate model, combined with realistic estimates of regional agricultural water use, to simulate the local and remote impacts of irrigation in California's Central Valley. We demonstrate a clear mechanism that the resulting increase in evapotranspiration and water vapor export significantly impacts the atmospheric circulation in the southwestern United States, including strengthening the regional hydrological cycle. We also identify that irrigation in the Central Valley initiates a previously unknown, anthropogenic loop in the regional hydrological cycle, in which summer precipitation is increased by 15%, causing a corresponding increase in Colorado River streamflow of ∼30%. Ultimately, some of this additional streamflow is returned to California via managed diversions through the Colorado River aqueduct and the All-American Canal. © 2013. American Geophysical Union. All Rights Reserved.

Liang P.-W.,University of Washington | Liao C.-Y.,University of Washington | Chueh C.-C.,University of Washington | Zuo F.,University of Washington | And 4 more authors.
Advanced Materials | Year: 2014

An effective method to control the rate of perovskite crystallization by incorporating rationally chosen additives into the perovskite precursor solutions is demonstrated. The processing additives simultaneously facilitate nucleation and modulate the kinetics of crystal growth during crystallization, leading to much smoother perovskite morphology with improved coverage area and crystal uniformity. As a result, it enables very high PCE (?12%) planar-heterojunction solar cells to be fabricated through the low-temperature solution processes (under 150 C). This study opens up a new direction for optimizing perovskite active layer properties to expand device performance ceilings. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Hedgehog (Hh) morphogen directs distinct cell responses according to its distinct signalling levels. Hh signalling stabilizes transcription factor cubitus interruptus (Ci) by prohibiting SCF(Slimb)-dependent ubiquitylation and proteolysis of Ci. How graded Hh signalling confers differential SCF(Slimb)-mediated Ci proteolysis in responding cells remains unclear. Here, we show that in COP9 signalosome (CSN) mutants, in which deneddylation of SCF(Slimb) is inactivated, Ci is destabilized in low-to-intermediate Hh signalling cells. As a consequence, expression of the low-threshold Hh target gene dpp is disrupted, highlighting the critical role of CSN deneddylation on low-to-intermediate Hh signalling response. The status of Ci phosphorylation and the level of E1 ubiquitin-activating enzyme are tightly coupled to this CSN regulation. We propose that the affinity of substrate-E3 interaction, ligase activity and E1 activity are three major determinants for substrate ubiquitylation and thereby substrate degradation in vivo.

Lin Y.-Y.,Academia Sinica, Taiwan | Liu T.-L.,Academia Sinica, Taiwan | Fuh C.-S.,National Taiwan University
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2011

In solving complex visual learning tasks, adopting multiple descriptors to more precisely characterize the data has been a feasible way for improving performance. The resulting data representations are typically high-dimensional and assume diverse forms. Hence, finding a way of transforming them into a unified space of lower dimension generally facilitates the underlying tasks such as object recognition or clustering. To this end, the proposed approach (termed MKL-DR) generalizes the framework of multiple kernel learning for dimensionality reduction, and distinguishes itself with the following three main contributions: First, our method provides the convenience of using diverse image descriptors to describe useful characteristics of various aspects about the underlying data. Second, it extends a broad set of existing dimensionality reduction techniques to consider multiple kernel learning, and consequently improves their effectiveness. Third, by focusing on the techniques pertaining to dimensionality reduction, the formulation introduces a new class of applications with the multiple kernel learning framework to address not only the supervised learning problems but also the unsupervised and semi-supervised ones. © 2006 IEEE.

Liu C.-S.,National Taiwan University | Atluri S.N.,University of California at Irvine
CMES - Computer Modeling in Engineering and Sciences | Year: 2011

For solving a system of nonlinear algebraic equations (NAEs) of the type: F(x) = 0, or Fi(xj) = 0; i; j = 1; : : : ;n, a Newton-like algorithm has several drawbacks such as local convergence, being sensitive to the initial guess of solution, and the time-penalty involved in finding the inversion of the Jacobian matrix ∂Fi=∂ xj. Based-on an invariant manifold defined in the space of (x; t) in terms of the residual-norm of the vector F(x), we can derive a gradient-flow system of nonlinear ordinary differential equations (ODEs) governing the evolution of x with a fictitious time-like variable t as an independent variable. We can prove that in the present novel Residual-Norm Based Algorithms (RNBAs), the residual-error is automatically decreased to zero along the path of x(t). More importantly, we have derived three iterative algoritms which do not involve the fictitious time and its stepsize Dt. We apply the three RNBAs to several numerical examples, revealing exponential convergences with different slopes and displaying the high efficiencies and accuracies of the present iterative algorithms. All the three presently proposed RNBAs: (i) are easy to implement numerically, (ii) converge much faster than the Newton's method, (iii) do not involve the inversion of the Jacobian ∂Fi=∂ xj, (iv) are suitable for solving a large system of NAEs, and (v) are purely iterative in nature. Copyright © 2011 Tech Science Press.

Hung H.,National Taiwan University | Wang C.-C.,Academia Sinica, Taiwan
Biostatistics | Year: 2013

Logistic regression has been widely applied in the field of biomedical research for a long time. In some applications, the covariates of interest have a natural structure, such as that of a matrix, at the time of collection. The rows and columns of the covariate matrix then have certain physical meanings, and they must contain useful information regarding the response. If we simply stack the covariate matrix as a vector and fit a conventional logistic regression model, relevant information can be lost, and the problem of inefficiency will arise. Motivated from these reasons, we propose in this paper the matrix variate logistic (MV-logistic) regression model. The advantages of the MV-logistic regression model include the preservation of the inherent matrix structure of covariates and the parsimony of parameters needed. In the EEG Database Data Set, we successfully extract the structural effects of covariate matrix, and a high classification accuracy is achieved. © 2012 The Author.

This article investigates how uncertainty in urban rents affects an efficient growth boundary designed by a regulator who prices a congestible public good at the average cost. A landowner decides the timing of development and competes with the regulator in a dynamic Stackelberg game. The regulator anticipates this timing decision and dynamically adjusts the growth boundary accordingly. The regulator should slacken the boundary control as urban rents pass their historically high levels, which is consistent with the existing land-use planning systems. The regulator should also design a smaller urban growth boundary if uncertainty arises because uncertainty will induce the landowners to postpone development. © 2014 © 2014 Regional Studies Association.

Chen W.-Y.,Yahoo! | Song Y.,Microsoft | Bai H.,Google | Lin C.-J.,National Taiwan University | Chang E.Y.,Google
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2011

Spectral clustering algorithms have been shown to be more effective in finding clusters than some traditional algorithms, such as k-means. However, spectral clustering suffers from a scalability problem in both memory use and computational time when the size of a data set is large. To perform clustering on large data sets, we investigate two representative ways of approximating the dense similarity matrix. We compare one approach by sparsifying the matrix with another by the Nyström method. We then pick the strategy of sparsifying the matrix via retaining nearest neighbors and investigate its parallelization. We parallelize both memory use and computation on distributed computers. Through an empirical study on a document data set of 193,844 instances and a photo data set of 2,121,863, we show that our parallel algorithm can effectively handle large problems. © 2011 IEEE.

Liu C.-S.,National Taiwan University
International Journal of Non-Linear Mechanics | Year: 2013

For the Falkner-Skan boundary layer equation we develop an innovative method by transforming the third-order governing equation into a non-linear system of three first-order ordinary differential equations (ODEs), whose coefficient matrix is zero trace. Hence, we can solve it by using an SL(3, ℝ) Lie-group shooting method, which allows us to search a missing initial value A at the left-end; moreover, A can be expressed as a closed-form function of r ∈ [0,1], where the best r is determined iteratively by matching the right-end boundary conditions. The present method converges very fast. When the target equation is matched precisely, the initial value A can be obtained accurately, and then we can apply the fourth-order Runge-Kutta (RK4) method to obtain a rather accurate numerical solution. © 2012 Elsevier Ltd.

Liu C.-S.,National Taiwan University | Atluri S.N.,University of California at Irvine
Engineering Analysis with Boundary Elements | Year: 2013

In this paper, the inverse Cauchy problem for Laplace equation defined in an arbitrary plane domain is investigated by using the collocation Trefftz method (CTM) with a better postconditioner. We first introduce a multiple-scale Rk in the T-complete functions as a set of bases to expand the trial solution. Then, the better values of Rk are sought by using the concept of an equilibrated matrix, such that the resulting coefficient matrix of a linear system to solve the expansion coefficients is best-conditioned from a view of postconditioner. As a result, the multiple-scale Rk can be determined exactly in a closed-form in terms of the collocated points used in the collocation to satisfy the boundary conditions. We test the present method for both the direct Dirichlet problem and the inverse Cauchy problem. A significant reduction of the condition number and the effective condition number can be achieved when the present CTM is used, which has a good efficiency and stability against the disturbance from large random noise, and the computational cost is much saving. Some serious cases of the inverse Cauchy problems further reveal that the unknown data can be recovered very well, although the overspecified data are provided only at a 20% of the overall boundary. © 2012 Elsevier Ltd.

Chen I.-K.,National Taiwan University
Journal of Statistical Physics | Year: 2013

We study the boundary singularity for stationary solutions of the linearized Boltzmann equation with hard-sphere potential. An asymptotic estimate for the gradient of the moments is established, which shows the logarithmic singularity near the boundary. Our formula holds for the solutions of the Milne and Kramers problems obtained by Bardos-Caflish-Nicolaenko (Commun. Pure Appl. Math. 49:323-452, 1986). Our theorem requires the Hölder continuity of the boundary data. In particular, it applies to the complete condensation problem for half space. © 2013 Springer Science+Business Media New York.

Liu C.-S.,National Taiwan University
Nonlinear Dynamics | Year: 2013

For the inverse vibration problem, a differential-algebraic equation (DAE) method is proposed to simultaneously estimate the time-dependent damping and stiffness coefficients by using two sets of displacement and velocity as input data. We combine the equations of motion and the supplemental data into a set of DAEs. We develop an implicit GL(n,ℝ) scheme and a Newton iterative algorithm to stably solve the DAEs to find the unknown structural coefficients. The unknown force is also recovered by the present method. A linear oscillator and a non-linear Duffing oscillator are used as testing examples. The estimated results are rather accurate and robust against random noise; hence, the new method can be used in the solutions of non-linear inverse vibration problems. © 2013 Springer Science+Business Media Dordrecht.

Liu C.-S.,National Taiwan University
International Journal of Non-Linear Mechanics | Year: 2013

The group-preserving scheme (GPS) developed in Liu [1] for solving a non-linear dynamical system ẋ=f(x,t) was based on the Lie-symmetry SOo(n,1). Here we derive a more fundamental GL(n,R) dynamics for x, and develop a relevant Lie-group scheme based on the Lie-symmetry GL(n,R), which is a Lie-group set large enough to cope all non-linear ordinary differential equations (ODEs). We find that the first-order explicit scheme based on GL(n,R) is equivalent to the GPS. Moreover, when one uses an implicit scheme based on GL(n,R), it converges very fast at each time marching step and the accuracy is raised several orders than the explicit method. For the dynamical system endowed with a rotational vector field we also develop an implicit SO(n) Lie-group integration method. Several numerical examples are examined, showing that the GL(n,R) and SO(n) Lie-group schemes have superior efficiency, accuracy and stability. © 2013 Elsevier Ltd.

Hsieh Y.S.,National Taiwan University
Sensors (Basel, Switzerland) | Year: 2013

This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

The genus Paedocypris has only recently been discovered and described and includes three species, all of which are miniature species and one, P. progenetica, is the smallest vertebrate species. Two previous studies investigating relationships of Paedocypris, based on either cytochrome b or morphology, placed the genus with Sundadanio and Danionella, two genera with miniature species in the formerly recognized family Cyprinidae. Our investigation of the phylogenetic relationships of Paedocypris using six nuclear genes and a broad survey of taxa in major lineages of the Cypriniformes identifies Paedocypris as a monophyletic group and the basal sister group to all Cypriniformes, not a species of the formerly recognized family Cyprinidae. These new relationships are also supported by previously proposed morphological characters but reinterpreted relative to ontogenetic hypotheses and outgroup comparisons used to determine synapomorphies. Miniaturization has occurred independently multiple times in the order, but mostly in the Rasborine Clade. Consequently, the hypothesis of a shared ancestral developmental truncation of multiple morphological features in genera with miniature species is rejected. While strong evidence exists for the new phylogenetic placement of Paedocypris as the sister group to the most diverse clade of freshwater fishes attempts to theorize more broadly as to evolutionary processes of miniaturization would be premature without more complete taxon sampling.Accompanying growing consistency of phylogenetic evidence of relationships in the Cypriniformes has come the consistent support of major clades within the previously recognized family Cyprinidae now recognized as a series of separate families, rendering the former Cyprinidae equivalent to Cyprinoidea. The revised family Cyprinidae includes species of the former subfamily Cyprininae, sister to Psilorhynchidae. The former subfamilies of Cyprininae, Acheilognathinae, Leuciscinae, and Gobioninae are elevated to families, and in keeping with consistency between phylogenetic relationships and classification the families Leptobarbidae and Tincidae are now recognized and the new families Tanichthyidae and Sundadanionidae are described. Paedocypris is recognized in a new superfamily, Paedocypridoidea, and family, Paedocyprididae. © 2010 Elsevier Inc.

Liu C.-S.,National Taiwan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2014

We recover an unknown initial temperature for a nonlinear heat conduction equation ut(x, t )= uxx(x, t )+ H (x, t, u, ux), under the Cauchy boundary conditions specified on the left-boundary. The method in the present paper transforms the Cauchy problem into an inverse heat source problem to find F (x) in Tt(x, t ) = Txx(x, t )+ H + F (x). By using the GL(N, R) Lie-group differential algebraic equations (LGDAE) algorithm to integrate the numerical method of lines discretized equations from sideways heat equation, we can fast recover the initial temperature and two boundary conditions on the right-boundary. The accuracy and efficiency are confirmed by comparing the exact solutions with the recovered results, where a large noisy disturbance is imposed on the Cauchy data. Copyright © 2014 Tech Science Press.

Liu C.-S.,National Taiwan University
Computers and Mathematics with Applications | Year: 2014

A better method than the least squares solution is proposed in this paper to solve ann-dimensional ill-posed linear equations system Ax=b in an m-dimensional column subspace Cm, which is selected in such a way that each column in Cm is in a closer proximity to b. We maximize the orthogonal projection of b onto y: = Ax to find an approximate solution x ∈ span{a, Cm}, where a is a nonzero free vector. Then, we can prove that the maximal projection solution (MP) is better than the least squares solution (LS) with ∥b-AxMP∥<∥b-AxLS∥. Numerical examples of inverse problems under a large noise maybe up to 30% are discussed which confirm the efficiency of presently developed MP algorithms: MPA and MPA(m). © 2014 Elsevier Ltd. All rights reserved.

Jean J.-H.,St. Johns University Taiwan | Lian F.-L.,National Taiwan University
IEEE Transactions on Control Systems Technology | Year: 2012

In this paper, we present the development of a robust visual servo system for object tracking applications of a nonholonomic mobile robot. The system mainly consists of an adaptive shape tracking algorithm and a robust visual servo controller. The adaptive shape tracking algorithm is designed to automatically detect the shape contours of moving objects, extract the shape parameters, and continuously track the object in shape parameter space. Based on direct measurements of the shape parameters, the visual servo controller is designed using the sliding mode control technique. Through a Lyapunov-based stability analysis, a sufficient condition on the selection of control gains to achieve the tracking goal in finite time is provided, and simulation and experimental tests of the proposed approach are illustrated. © 2012 IEEE.

Lin P.-Y.,National Taiwan University
Journal of Mechanisms and Robotics | Year: 2012

This paper proposes a general approach for designing spatial statically balanced mechanisms with articular joints utilizing ideal zero-free-length springs. The proposed statically balanced mechanism can counterbalance the gravitational forces and provides a perfect static equilibrium at any configuration. The method of the paper is based on the energy approach, and a generalized coordinate system is developed to define the configuration of a spatial mechanism and to be a vector basis for the derivation of potential energy. By incorporating the gravitational forces and the spring forces into the system, the stiffness matrix of a spring-loaded mechanism is proposed. The perfect static balance is observed when the stiffness matrix is a diagonal matrix, from which, the design equations can be readily obtained. The closed-form solution of spring design parameters of a statically balanced, spatial, three-articular arm is obtained as a design example. The simulations of the conceptual design are performed by commercial computer software, and the static equilibrium of a quasi-static continuous motion is verified. © 2012 American Society of Mechanical Engineers.

Luh T.-Y.,National Taiwan University
Pure and Applied Chemistry | Year: 2010

A summary of recent advances in the chemistry and photophysics of alternating dialkylsilylene- divinylarene copolymers is presented. The silicon moieties are considered to be insulating tetrahedral spacers in these copolymers. The substituents on silicon can readily be tuned, and the steric environment of these substituents around the silicon may dictate the conformation (or helicity) of the copolymers (the Thorpe-Ingold effect) and hence their photophysical properties. Because different chromophores can be regio regularly introduced into the polymeric chain, these copolymers have been used as models to study energy transfer and photoinduced electron transfer (PET), as well as chiroptical transfer. © 2010 IUPAC.

Wang Y.-T.,National Taiwan University
Journal of Intellectual Disability Research | Year: 2013

Background The aim of this exploratory study is to examine to what extent adults with intellectual disabilities (ID) in Taiwan are socially excluded and to identify the factors that are potentially associated with such social exclusion. Methods The research method of this study is secondary data analysis, using descriptive and χ2 statistical analysis. Two data sets, from the 2003 and 2006 surveys entitled 'Survey of Living Situation for People with Disabilities in Taiwan', were used (n=572; n=618). In addition, 'independent living/living within the community' (as opposed to residing in an institution), 'employment' and 'household economic situation/residing in a low-income household' were social exclusion indicators in this study. Results The results revealed that in the 2003 (2006) survey, 81.9% (79.6%) of the subjects fell into at least one category of social exclusion, 11.3% (12.3%) fell into two or more categories and 0.2% (1.1%) fell into all three categories. Moreover, older women with ID, with no spouse or partner, lower educational levels and greater severity of the disability had a significantly greater likelihood of being subjected to more categories of social exclusion. Conclusions The finding that the proportion of adults with ID and no social exclusion has risen from 18.1% in 2003 to 20.4% in 2006 represents an encouraging trend. However, there has been a marked increase in the proportion of the subjects with more categories of social exclusion, particularly with regard to those who have to endure all three categories, from 0.2% in 2003, to 1.1% in 2006. This implies that, at the time of the last survey, there was still considerable room for improvement in the social inclusion of adults with ID in Taiwan. © 2012 The Authors. Journal of Intellectual Disability Research © 2012 John Wiley & Sons Ltd, MENCAP & IASSID.

Liu C.-S.,National Taiwan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2011

Based-on the ordinary differential equations defined on an invariant manifold, we propose a theoretical procedure to derive a Relaxed Steepest Descent Method (RSDM) for numerically solving an ill-posed system of linear equations when the data are polluted by random noise. The invariant manifold is defined in terms of a squared-residual-norm and a fictitious time-like variable, and in the final stage we can derive an iterative algorithm including a parameter, which is known as the relaxation parameter. Through a Hopf bifurcation, this parameter indeed plays a major role to switch the situation of slow convergence to a new situation with faster convergence. Several numerical examples, including the first-kind Fredholm integral equation and backward heat conduction problem, are examined and compared with exact solutions, revealing that the RSDM has superior computational efficiency and accuracy even for the highly ill-conditioned linear equations with a large noise imposed on the given data. Copyright © 2011 Tech Science Press.

Liu C.-S.,National Taiwan University
Engineering Analysis with Boundary Elements | Year: 2013

In this paper we numerically solve both the direct and the inverse Cauchy problems of biharmonic equation by using a multiple-scale Trefftz method (TM). The approximate solution is expressed to be a linear combination of T-complete bases, and the unknown coefficients are determined to satisfy the boundary conditions, by solving a resultant linear equations system. We introduce a better multiple-scale in the T-complete bases by using the concept of equilibrated norm of the coefficient matrix, such that the explicit formulas of these multiple scales can be derived. The condition number of the coefficient matrix can be significantly reduced upon using these better scales; hence, the present multiple-scale Trefftz method (MSTM) can effectively solve the inverse Cauchy problem without needing of the overspecified data, which is an incomplete Cauchy problem. Numerical examples reveal the efficiency that the new method can provide a highly accurate numerical solution even the problem domain might have a corner singularity, and the given boundary data are subjected to a large random noise. © 2013 Elsevier Ltd.

We are concerned with the reconstruction of an unknown spacedependent rigidity coefficient in a wave equation. This problem is known as one of the inverse scattering problems. Based on a two-point Lie-group equation we develop a Lie-group adaptive method (LGAM) to solve this inverse scattering problem through iterations, which possesses a special character that by using only two boundary conditions and two initial conditions, as those used in the direct problem, we can effectively reconstruct the unknown rigidity function by a self-adaption between the local in time differential governing equation and the global in time algebraic Lie-group equation. The accuracy and efficiency of the present LGAM are assessed by comparing the imaged results with some postulated exact solutions. By means of LGAM, it is quite versatile to handle the wave inverse scattering problem for the image of the rigidity coefficient without needing any extra information from the wave motion. Copyright © 2010 Tech Science Press.

Gu J.-A.,National Taiwan University | Lee C.-C.,National Tsing Hua University | Geng C.-Q.,National Tsing Hua University | Geng C.-Q.,National Center for Theoretical science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

We propose the simplest model of teleparallel dark energy with purely a non-minimal coupling to gravity but no self-potential, a single model possessing various interesting features: simplicity, self-potential-free, the guaranteed late-time cosmic acceleration driven by the non-minimal coupling to gravity, tracker behavior of the dark energy equation of state at earlier times, a crossing of the phantom divide at a late time, and the existence of a finite-time future singularity. We find the analytic solutions of the dark-energy scalar field respectively in the radiation, matter, and dark energy dominated eras, thereby revealing the above features. We further illustrate possible cosmic evolution patterns and present the observational constraint of this model obtained by numerical analysis and data fitting. © 2012 Elsevier B.V.

Surfactants are a major class of emerging pollutants widely used in large quantities in everyday life and commonly found in surface waters worldwide. Freshwater planarian was selected to examine the effects of different surfactants by measuring mortality, mobility, and membrane-bound enzyme activities. Among the 10 surfactants tested, the acute toxicities of betaine and polyethylene glycol (PEG-200) to planarians were relatively low, with a median lethal concentration (LC50) greater than 10,000mg/L. The toxicity to planarians of the other eight surfactants based on 48-h LC50 could be arranged in the descending order of cetylpyridinum chloride (CPC)>4-tert-octylphenol (4-tert-OP)>ammonium lauryl sulfate>benzalkonium chloride>saponin>sodium lauroylsarcosinate>dioctyl sulfosuccinate>dodecyl trimethyl ammonium bromide (DTAB). Both CPC and 4-tert-OP were very toxic to planarians, with 48-h LC50 values <1mg/L. The median effective concentrations (EC50s) of planarian mobility were in the 0.1 to 50mg/L range and were in the same range as the 24-h LC50 of planarians exposed to different surfactants, except for DTAB. In addition, significant inhibition of cholinesterase activity activities was found in planarians exposed to 4-tert-OP at 2.5 and 5mg/L and to saponin at 10mg/L after 2-h treatments. This result suggests that planarian mobility responses can be used as an alternative indicator for acute toxicity of surfactants after a very short exposure period. © 2012 SETAC.

Chung C.-H.,Chung Shan Institute of Science and Technology | Chen M.-S.,National Taiwan University
Automatica | Year: 2012

This paper proposes a new adaptive feedforward cancellation (AFC) control that achieves periodic tracking and/or periodic disturbance rejection. The new control design is a direct scheme in the sense that it adaptively updates the desired control without estimating the unknown disturbance. The proposed new control has several advantages. First, its adaptation gain can be arbitrarily chosen without upsetting the system stability if given the exact system model. Second, it can be applied to not only minimum-phase systems, but also non-minimum phase systems. Third, the new control law is independent of where the disturbance enters the system. Finally, a robustness analysis is made to show that the proposed control is robust with respect to un-modelled dynamics. © 2011 Elsevier Ltd. All rights reserved.

Superparamagnetic iron oxide nanoparticles have been used in clinical applications as a diagnostic contrasting agent. Previous studies showed that iron oxide nanoparticles deposited in the liver and spleen after systemic administration. The present study investigated the effect of iron oxide nanoparticles on antigen-specific immune responses in mice sensitized with the T cell-dependent antigen ovalbumin (OVA). BALB/c mice were intravenously administered with a single dose of iron oxide nanoparticles (10-60 mg Fe/kg) 1 hour prior to OVA sensitization, and the serum antibody production and splenocyte reactivity were examined 7 days later. The serum levels of OVA-specific IgG(1) and IgG(2a) were significantly attenuated by treatment with iron oxide nanoparticles. The production of interferon-γ and interleukin-4 by splenocytes re-stimulated with OVA in culture was robustly suppressed in mice administered with iron oxide nanoparticles. The viability of OVA-stimulated splenocytes was also attenuated. In contrast, treatment with iron oxide nanoparticles did not affect the viability of splenocytes stimulated with concanavalin A, a T-cell mitogen. Collectively, these data indicate that systemic exposure to a single dose of iron oxide nanoparticles compromises subsequent antigen-specific immune reactions, including the serum production of antigen-specific antibodies, and the functionality of T cells.

Shen C.C.,National Taiwan University
International journal of nanomedicine | Year: 2011

Accumulating evidence indicates that iron oxide nanoparticles modulate immune responses, and induce oxidative stress in macrophages. It was recently reported that iron oxide nanoparticles attenuated antigen-specific immunity in vivo, though the underlying mechanism remains elusive. The present study investigates the direct effect of iron oxide nanoparticles on antigen-specific cytokine expression by T cells, and potential underlying mechanisms. Ovalbumin-primed splenocytes were exposed to iron oxide nanoparticles, followed by restimulation with ovalbumin. Cell viability, cytokine production, and cellular levels of glutathione and reactive oxygen species were measured. The splenocyte viability and the production of interleukin-2 and interleukin-4 were unaffected, whereas interferon-γ production was markedly attenuated by iron oxide nanoparticles (10-100 μg iron/mL) in a concentration-dependent manner. Iron oxide nanoparticles also transiently diminished the intracellular level of glutathione, with a peak response at 6 hours posttreatment. The effects of iron oxide nanoparticles on interferon-γ and glutathione were attenuated by the presence of N-acetyl-L-cysteine, a precursor of glutathione. However, iron oxide nanoparticles did not influence the generation of reactive oxygen species. Iron oxide nanoparticles induced a differential effect on antigen-specific cytokine expression by T cells, in which the T helper 1 cytokine IFN-γ was sensitive, whereas the T helper 2 cytokine interleukin-4 was refractory. In addition, the suppressive effect of iron oxide nanoparticles on interferon-γ was closely associated with the diminishment of glutathione.

Hsu S.,National Taiwan University
Computers and Education | Year: 2011

The expansion of information and communication technology (ICT) infrastructure in schools is expected to promote learning. To what extent teachers are utilizing the new ICT tools to engage students in learning activities remains a question. This study reports what kind of activities teachers are likely to assign students, and what type of teachers are more likely to assign such activities. Teacher ICT usage and student ICT assignments are examined using a sample of 3729 elementary and junior high school teachers in Taiwan. The results from correlation and regression analysis indicate that teachers who infrequently use basic ICT tools such as word processing rarely assign student ICT activities. At the other end of spectrum, teachers who create complicated multimedia materials are most likely to assign student multimedia activities. Regression results show that teachers' frequency of building websites is the best predictor for assigning ICT-based sharing activities to students, though the likelihood is greater for junior high school than elementary school teachers. The results suggest that teachers assign students activities which require a variety of ICT tools, and teachers' own ICT practices influence the type of ICT activities they assign to students. © 2010 Elsevier Ltd. All rights reserved.

Jeng S.-K.,National Taiwan University
IEEE Transactions on Antennas and Propagation | Year: 2011

FDTD solutions have their own properties distinct from the discrete samples of corresponding continuous wave solutions. Thus, the discrete equivalent to the Green's function is needed for applications like the one using a hybrid absorbing boundary condition which couples the FDTD algorithm with integral operators for nonconvex scatterers. In this paper we propose a new closed-form expression for the 3-D dyadic FDTD-compatible Green's function in infinite free space via a novel approach with the ordinary z-transform along with the spatial partial difference operators. The final expression involves a summation of standing wave modes with time-varying coefficients. The propagation of waves in the Yee's grid can be interpreted by the selective property of the time-varying coefficients, which is very different from the conventional concept of a traveling wave. The traditional dispersion analysis using plane waves for the FDTD algorithm in a source-free region may not be applicable to explain the wave propagation phenomenon through our analytic expression, because the corresponding z-transform diverges for z on the unit circle. © 2006 IEEE.

Liu C.-S.,National Taiwan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2012

An iterative algorithm based on the critical descent vector is proposed to solve an ill-posed linear system: Bx = b. We define a future cone in the Minkowski space as an invariant manifold, wherein the discrete dynamics evolves. A critical value ac in the critical descent vector u =αcr+BTr is derived, which renders the largest convergence rate as to be the globally optimal iterative algorithm (GOIA) among all the numerically iterative algorithms with the descent vector having the form u =αr+BTr to solve the ill-posed linear problems. Some numerical examples are used to reveal the superior performance of the GOIA. Copyright © 2012 Tech Science Press.

Liu C.-S.,National Taiwan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2012

The iterative algorithms based on the concept of best vector are proposed to solve an ill-conditioned linear system: Bx-b = 0, which might be a discretization of linear inverse problem. In terms of r := Bx-b and a monotonically increasing positive function Q(t) of a time-like variable t, we define a future cone in the Minkowski space, wherein the discrete dynamics of the proposed algorithm is evolved. We propose two methods to approximate the best vector B-1r, and obtain three iterative algorithms for solving x, which we label them as the steepest-descent and optimal vectors iterative algorithm (SOVIA), the mixed optimal iterative algorithm (MOIA), as well as the optimal vector iterative algorithm (OVIA). These algorithms are compared with the relaxed steepest descent method (RSDM), the conjugate gradient method (CGM) and an optimal iterative algorithm with an optimal descent vector (OIA/ODV) by testing several ill-posed linear inverse problems. Copyright © 2012 Tech Science Press.

Su J.-T.,Hewlett - Packard | Liu C.-W.,National Taiwan University
IEEE Transactions on Power Electronics | Year: 2013

In this paper, a novel phase-shedding control scheme for multiphase interleaved dc-dc converters is proposed to improve the light load efficiency. The proposed phase-shedding scheme is based upon power efficiency estimation with a numerically constructed lookup table and a phase configuration selector to automatically determine the load current point of phase shedding for the minimization of the power loss during the light load condition. The proposed scheme is verified on a three-phase-interleaved dc-dc synchronous buck converter with a 12V input and 1.2V, 60A output. Experimental results are presented to demonstrate the effectiveness of the proposed scheme. © 1986-2012 IEEE.

Romano A.E.,National Taiwan University | Romano A.E.,Kyoto University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

Assuming the definition of the inversion problem (IP) as the exact matching of the terms in the low redshift expansion of cosmological observables calculated for different cosmological models, we solve the IP for D L(z) and the redshift spherical shell mass density mn(z) for a central observer in a Lemaitre-Tolman-Bondi (LTB) space without cosmological constant and a generic ΛCDM model. We show that the solution of the IP is unique, corresponds to a matter density profile which is not smooth at the center, and that the same conclusions can be reached expanding self-consistently to any order all the relevant quantities. Contrary to the case of a single observable inversion problem, it is impossible to solve the IP (LTB vs ΛCDM) for both mn(z) and DL(z) while setting one of the two functions k(r) or tb(r) to zero, even allowing nonsmooth matter profiles. Our conclusions are general, since they are exclusively based on comparing directly physical observables in redshift space, and do not depend on any special ansatz or restriction for the functions defining a LTB model. © 2010 The American Physical Society.

Miki T.,National Taiwan University
Ecological Research | Year: 2012

Plants affect soil conditions, which in turn alter plant growth and interspecific competition, forming plant-soil feedback (PSF) systems. PSF is a good example of bidirectional interactions between biomes and the non-living environments, acting as a major driving force of community structure and ecosystem function. Among the major types of PSF mediated by various soil components, there are many holes in our knowledge of the interactions between PSF mediated by plant species-specific litter and PSF mediated by soil microbes. Here I discuss the role of the functional diversity of microbial decomposers in litter-mediated PSF and also propose new hypotheses on the role of microbial diversity in PSF mediated by pathogenic and mutualistic soil microbes. I also review how PSF interacts with human-induced environmental change, i. e., direct drivers of change in the ecosystem (e. g. climate change and the invasion of alien species). Many authors have suggested that the impact of alien plant species on ecosystems is mediated by PSF, which also interacts with other direct drivers, such as climate change. Using a simple model of litter-mediated PSF with microbial decomposers, I confirm that the interactions between PSF and other direct drivers affect the invasion process of alien species. The model also demonstrates that the functional diversity of microbial decomposers accelerates or decelerates the speed of the invasion depending on the environmental change scenarios. Further theoretical and empirical studies are needed to derive general predictions on how exogenous environmental change induced by human activities alters communities and ecosystems through disturbance or modification of endogenous community-ecosystem interactions, such as the functioning of PSF. © 2012 The Ecological Society of Japan.

Chang Y.J.,National Taiwan University | Chow T.J.,Academia Sinica, Taiwan
Journal of Materials Chemistry | Year: 2011

A new series of organic dyes containing a triarylamine donor group, a triarylene-linked bridging moiety, and a cyanoacrylic acid acceptor group were synthesized through a simple procedure in high yields. A selected set of substituents were added onto the phenyl group ortho to the cyanoacrylic acid in order to examine their influences on the performance of dye-sensitized solar cells (DSSCs). Their photochemical behaviors were examined under AM1.5 solar condition (100 mW cm-2). A typical device made with a compound containing a -CF3 substituent (PSP-CF3) displayed a short-circuit current (Jsc) 15.16 mA cm-2, an open-circuit voltage (Voc) 0.68 V, a fill factor (ff) 0.68, corresponding to an overall conversion efficiency of 7.0% and a maximal monochromatic incident photon-to-current conversion efficiency (IPCE) 78%. Their photophysical and electrochemical properties were analyzed with the aid of a time-dependent density functional theory (TDDFT) model with the B3LYP functional. Their HOMO and LUMO energy levels are verified by both electrochemical measurements and theoretical calculations. © 2011 The Royal Society of Chemistry.

Chang Y.J.,National Taiwan University | Chow T.J.,Academia Sinica, Taiwan
Journal of Materials Chemistry | Year: 2011

Two red color luminescent dyes, 4-(dicyanomethylidene)-2-tert-butyl-6-(2- (1-(4-tert-butylphenyl)-1,2,3,4-tetrahydroquinolin-6-yl)vinyl)-4H-pyran (OJ1) and 4-(dicyanomethylidene)-2-tert-butyl-6-(2-(1-(4-tert-butylphenyl)-2,3- dihydro-2-methylindolin-5-yl)vinyl)-4H-pyran (OJ2), were synthesized readily in high yields and were used in the fabrication of organic light-emitting diodes (OLEDs). The physical properties of these materials are fully investigated in this report. Their structures are analogous to the well-known red dye, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (DCJTB), yet with better electrostability. A typical device made with OJ2 doped 1% in aluminium tris(8-hydroxyquinolinate) (Alq3) displayed a red light with a narrow bandwidth (fwhm 72 nm) at λmax 615 nm corresponding to a CIE coordinate (0.62, 0.38). The device can be turned on at 3.5 V, and reaches a luminance intensity of 43400 cd m at ca. 20 V. It shows a luminance efficiency of 6.46 cd A-1, a power efficiency of 2.04 lm W-1, and an external quantum efficiency of 3.27%. The performances of devices are tunable either by adjusting the doping concentrations or by changing the device configurations. © The Royal Society of Chemistry 2011.

Liu C.-S.,National Taiwan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2013

In order to solve an ill-posed linear problem, we propose an innovative Jacobian type iterative method by presetting a conditioner before the steepest descent direction. The preconditioner is derived from an invariant manifold approach, which includes two parameters α and γ to be determined. When the weighting parameter a is optimized by minimizing α properly defined objective function, the relaxation parameter γ can be derived to accelerate the convergence speed under a switching criterion. When the switch is turned-on, by using the derived value of g it can pull back the iterative orbit to the fast manifold. It is the first time that we have a formula for the relaxation parameter, by recognizing that g is specified case by case, previously. The presently developed optimal and generalized steepest descent method with an alternate value of the relaxation parameter is able to overcome the ill-posedness of linear inverse problem, and provides a rather accurate numerical solution. Copyright © 2013 Tech Science Press.

Liu C.-S.,National Taiwan University
CMES - Computer Modeling in Engineering and Sciences | Year: 2013

In the present paper, we propose a novel two-side equilibration method to properly reduce the condition number of a given non-singular matrix only through a few operations. Then, two different conditioners together with the conjugate gradient method (CGM) are developed, which can overcome the defect of CGM, being not vulnerable to noisy disturbance exerted on an ill-posed linear system. The twoside CGM (TSCGM) and the pre-conditioning CGM (PrCGM) are convergent fast and accurate in solving linear inverse problems and the linear Hilbert problem under a large random noise. Copyright © 2013 Tech Science Press.

Tu Y.-K.,University of Leeds | Kramer N.,TU Munich | Lee W.-C.,National Taiwan University
Epidemiology | Year: 2012

In the analysis of trends in health outcomes, an ongoing issue is how to separate and estimate the effects of age, period, and cohort. As these 3 variables are perfectly collinear by definition, regression coefficients in a general linear model are not unique. In this tutorial, we review why identification is a problem, and how this problem may be tackled using partial least squares and principal components regression analyses. Both methods produce regression coefficients that fulfill the same collinearity constraint as the variables age, period, and cohort. We show that, because the constraint imposed by partial least squares and principal components regression is inherent in the mathematical relation among the 3 variables, this leads to more interpretable results. We use one dataset from a Taiwanese health-screening program to illustrate how to use partial least squares regression to analyze the trends in body heights with 3 continuous variables for age, period, and cohort. We then use another dataset of hepatocellular carcinoma mortality rates for Taiwanese men to illustrate how to use partial least squares regression to analyze tables with aggregated data. We use the second dataset to show the relation between the intrinsic estimator, a recently proposed method for the age-period-cohort analysis, and partial least squares regression. We also show that the inclusion of all indicator variables provides a more consistent approach. R code for our analyses is provided in the eAppendix (http://links.lww.com/EDE/A569). © 2012 by Lippincott Williams & Wilkins.

Lin F.-H.,National Taiwan University | Lin F.-H.,Aalto University
Magnetic Resonance in Medicine | Year: 2013

Magnetic resonance imaging (MRI) typically achieves spatial encoding by measuring the projection of a q-dimensional object over q-dimensional spatial bases created by linear spatial encoding magnetic fields (SEMs). Recently, imaging strategies using nonlinear SEMs have demonstrated potential advantages for reconstructing images with higher spatiotemporal resolution and reducing peripheral nerve stimulation. In practice, nonlinear SEMs and linear SEMs can be used jointly to further improve the image reconstruction performance. Here, we propose the multidimensionally encoded (MDE) MRI to map a q-dimensional object onto a p-dimensional encoding space where p > q. MDE MRI is a theoretical framework linking imaging strategies using linear and nonlinear SEMs. Using a system of eight surface SEM coils with an eight-channel radiofrequency coil array, we demonstrate the five-dimensional MDE MRI for a two-dimensional object as a further generalization of PatLoc imaging and O-space imaging. We also present a method of optimizing spatial bases in MDE MRI. Results show that MDE MRI with a higher dimensional encoding space can reconstruct images more efficiently and with a smaller reconstruction error when the k-space sampling distribution and the number of samples are controlled. © 2012 Wiley Periodicals, Inc.

Hung M.-H.,National Taiwan University
Genes and Immunity | Year: 2014

Cullin 4B (CUL4B), a member of the cullin protein family, is a scaffold protein of the CUL4B-RING-E3 ligase complex that ubiquitinates intracellular proteins.CUL4B's targets include cell cycle-regulated proteins and DNA replication-related molecules. In this study, we generated myeloid-specific Cul4b-deficient mice (Cul4bf/y;LysM-CreKI/KI) to investigate the influence of Cul4b deficiency on innate immunity, especially on the function of macrophages. Our results show that an intraperitoneal injection of lipopolysaccharide (LPS) led to a significant decrease in body weights and increased leukocyte infiltrates with increased chemokines in the peritoneal cavity of Cul4bf/y;LysM-CreKI/KI mice. However, the proinflammatory cytokines, IL-6 and TNF-α did not increase in LPS-injected Cul4bf/y;LysM-CreKI/KI mice. Furthermore, bone marrow-derived macrophages from Cul4bf/y;LysM-CreKI/KI mice secreted higher levels of chemokines but lower levels of TNF-α and IL-6 upon LPS stimulation. Of note, increased proliferation of Cul4b-deficient macrophages was also observed. These results show that myeloid-specific Cul4b deficiency worsens LPS-induced peritonitis. In addition, Cul4b deficiency leads to enhanced DNA replication and proliferation, increased production of chemokines but a decreased production of proinflammatory cytokines of macrophages. Our data highlight a new role of cullin family, CUL4B, in the immune system.Genes and Immunity advance online publication, 5 June 2014; doi:10.1038/gene.2014.32.

He X.-G.,Shanghai JiaoTong University | He X.-G.,National Taiwan University | Valencia G.,Iowa State University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

It is expected that the LHC will soon discover the Higgs boson, or that failure to find it will severely constrain its production cross-section over a large mass range. Either one of these results spells trouble for a fourth generation that significantly enhances the Higgs production cross-section at LHC. In fact the LHC has already ruled out a SM Higgs mass in the range of 120-600 GeV with a fourth generation at the 95% C.L. In this Letter we explore options within extended scalar sectors to maintain the viability of a heavy fourth generation if an enhanced (relative to the standard model) Higgs production cross-section is not observed. © 2011 Elsevier B.V.

Lin J.J.,National Taiwan University
Journal of sports sciences | Year: 2010

Physiological tremor and strength during the maintenance of shoulder position occur during a precision aiming task, such as archery. It is unclear how positions for precision demands affect physiological tremor and associated muscular activities. The purpose of this study was to assess the tremor amplitude and muscular activities of the shoulder between the various positions for precision demands. Ten males (age 21.9 +/- 2.0 years) participated in the study. Electromyography (EMG) was quantified on eight humeral/scapular muscles. The tremor was measured by the acceleration component of a motion tracking sensor in the 3-7 Hz and 8-12 Hz frequency bands. Participants simulated six preparatory archery shooting positions (3 arm angles x 2 arm draw positions) and performed isometric contractions. The relative root mean square (RMS) amplitudes of the shoulder muscles were significantly greater for the full drawing position compared with the partial position (humeral muscles: P = 0.011; scapular muscles: P = 0.026). In the full drawing position, increased humeral/scapular muscle EMG amplitude was moderately associated with an increased power spectrum of 8-12/3-7 Hz tremor in humerus/scapula motion (R = 0.43-0.57). To minimize fluctuations in high strength muscle performance, 90 degrees of elevation in the full drawing position may be a suitable position for demands in archery. In addition, scapular muscle amplitude is important for stability to reduce humerus tremor during archery performance.

Gao Z.-M.,National Taiwan University
Computer Assisted Language Learning | Year: 2011

Previous studies on self-correction using corpora involve monolingual concordances and intervention from instructors such as marking of errors, the use of modified concordances, and other simplifications of the task. Can L2 learners independently refine their previous outputs by simply using a parallel concordancer without any hints about their errors and guidelines from instructors? This paper addresses this question and reports a pilot study about the effects and use of a parallel concordancer in a Chinese-English translation task. Twenty-one subjects, whose English reading proficiency attained higher-intermediate level, participated in the study, in which they used the Yahoo Chinese-English bilingual dictionary in the pretest and employed the CERT parallel Chinese-English concordancer to modify their translations in the posttest. The results indicated that the mean score in the posttest was significantly higher than that in the pretest, suggesting that learners can independently make corrections by consulting parallel corpora without any simplification of the task as well as hints and guidelines from their instructors. Inspection of the subjects' translations showed that the improvements made in the posttest centered on phraseology involving word choices and word combinations. The users' attitudes toward CERT as well as the theoretical implications of parallel concordancers in second language acquisition theories are discussed. © 2011 Taylor & Francis.

By employing the pseudospectral time-domain (PSTD) simulation technique, we analyze the propagation of monochromatic light through a macroscopic scattering medium. Simulation results show that, monochromatic light can be directed through a scattering medium and focus into a narrow peak; a range of wavelengths has been simulated. Furthermore, we compare: i) focusing monochromatic light through a macroscopic scattering medium, and, ii) focusing monochromatic light through vacuum. Based upon numerical solutions of Maxwell’s equations, we demonstrate: with a fully-surrounding wavefront of specific amplitude and phase, sub-diffraction focusing can be achieved with monochromatic light, with or without the presence of a scattering medium. © 2015 Optical Society of America.

Lin Y.-H.,National Taiwan University | Wu J.-L.,Communication and Multimedia Laboratory
IEEE Transactions on Image Processing | Year: 2014

The objective approaches of 3D image quality assessment play a key role for the development of compression standards and various 3D multimedia applications. The quality assessment of 3D images faces more new challenges, such as asymmetric stereo compression, depth perception, and virtual view synthesis, than its 2D counterparts. In addition, the widely used 2D image quality metrics (e.g., PSNR and SSIM) cannot be directly applied to deal with these newly introduced challenges. This statement can be verified by the low correlation between the computed objective measures and the subjectively measured mean opinion scores (MOSs), when 3D images are the tested targets. In order to meet these newly introduced challenges, in this paper, besides traditional 2D image metrics, the binocular integration behaviors-the binocular combination and the binocular frequency integration, are utilized as the bases for measuring the quality of stereoscopic 3D images. The effectiveness of the proposed metrics is verified by conducting subjective evaluations on publicly available stereoscopic image databases. Experimental results show that significant consistency could be reached between the measured MOS and the proposed metrics, in which the correlation coefficient between them can go up to 0.88. Furthermore, we found that the proposed metrics can also address the quality assessment of the synthesized color-plus-depth 3D images well. Therefore, it is our belief that the binocular integration behaviors are important factors in the development of objective quality assessment for 3D images. © 2013 IEEE.

Lin Y.-W.,National Changhua University of Education | Huang C.-C.,National Taiwan Ocean University | Chang H.-T.,National Taiwan University
Analyst | Year: 2011

Monitoring the levels of potentially toxic metal (PTM) ions (e.g., Hg 2+, Pb2+, Cu2+) in aquatic ecosystems is important because these ions can have severe effects on human health and the environment. Gold (Au) nanomaterials are attractive sensing materials because of their unique size- and shape-dependent optical properties. This review focuses on optical assays for Hg2+, Pb2+, and Cu2+ ions using functionalized Au nanomaterials. The syntheses of functionalized Au nanomaterials are discussed. We briefly review sensing approaches based on changes in absorbance resulting from metal ion-induced aggregation of Au nanoparticles (NPs) or direct deposition of metal ions onto Au NPs. The super-quenching properties of Au NPs allow them to be employed in 'turn on' and 'turn off' fluorescence approaches for the sensitive and selective detection of Hg2+, Pb2+, and Cu2+ ions. We highlight approaches based on fluorescence quenching through analyte-induced aggregation or the formation of metallophilic complexes of Au nanodots (NDs). We discuss the roles of several factors affecting the selectivity and sensitivity of the nanosensors toward the analytes: the size of the Au nanomaterial, the length and sequence of the DNA or the nature of the thiol, the surface density of the recognition ligand, and the ionic strength and pH of the buffer solution. In addition, we emphasize the potential of using new nanomaterials (e.g., fluorescent silver nanoclusters) for the detection of PTM ions. © 2011 The Royal Society of Chemistry.

This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally. © 2010 by the authors.

Chang L.-Y.,National Taiwan University
Journal of Air Transport Management | Year: 2014

Gravity models have long served as a framework for analyzing bilateral flows, trade and many other activities. To estimate a gravity model, (parametric) linear regression techniques have been commonly employed to develop the relationship between passenger flows and factors that can significantly influence these flows. This study explores the application of an alternative method, the non-parametric multivariate adaptive regression spline (MARS) technique, to identify the determinants for air passenger flows between pairs of countries. The data of 2006 and 2007 air passenger flows between pairs of countries in the APEC region were collected to develop the MARS models. Results indicate that distance between the countries, annual import value, national per capita income, unemployment rate and consumer price index of the origin country, as well as GDP, annual import value, and consumer price index of the destination country are significant determinants for bilateral air passenger flows. © 2013 Elsevier Ltd.

Chang W.-H.,National Taiwan University
Oncogene | Year: 2016

HLJ1 (DNAJB4), a DNAJ/Hsp40 chaperone, has emerged as a novel prognostic marker in lung cancers; however, the molecular contribution and functionality in neoplastic diseases remain to be established. This study demonstrated that HLJ1 inhibits epithelial–mesenchymal transition in vitro and reduces lung cancer metastasis in vivo. Using shRNA silencing and ectopic expression of HLJ1, we found that HLJ1 not only suppresses catalytic activity of Src but also downregulates the formation of oncogenic complexes associated with the EGFR, FAK and STAT3 signaling pathways. A screen of specimens from HLJ1-knockout mice and lung cancer patients validated that HLJ1 expression is inversely correlated with Src activity. Mechanistically, HLJ1 protein directly bound to catalytic and protein-binding domains of Src through its amino acid Y172 and the P301/P304 motif. Following Src-induced HLJ1 phosphorylation at Y172, HLJ1–Src interaction was elevated, resulting in Src inhibition and malignancy suppression. Interestingly, both Src-binding regions also occurred in other DNAJB family members and contributed to anti-invasive activities of DNAJB proteins. We conclude that HLJ1 is an endogenous Src inhibitor that can suppress cancer metastasis through complex interacting mechanisms. This HLJ1–Src complex might provide a promising molecular model for developing new anticancer strategies.Oncogene advance online publication, 11 April 2016; doi:10.1038/onc.2016.106. © 2016 Macmillan Publishers Limited

Xia Z.,University of Science and Technology of China | Liu R.-S.,National Taiwan University
Journal of Physical Chemistry C | Year: 2012

A series of new luminescent emission-tunable phosphors Ca 2Al 3O 6F:Ce 3+,Tb 3+ have been synthesized by a high temperature solid-state reaction. The UV-vis reflectance, photoluminescence emission and excitation spectra, the lifetime, and the effect of Tb 3+ concentration are investigated in detail. The intense green emission is realized in the Ca 2Al 3O 6F:0.08Ce 3+,0.05Tb 3+ phosphors on the basis of the highly efficient energy transfer from Ce 3+ to Tb 3+ with an efficiency of over 90%. The energy transfer mechanism from Ce 3+ to Tb 3+ in the Ca 2Al 3O 6F host was ascribed to the exchange interactions, and the formation of the Ce-Ce clusters and Ce-Tb clusters should be the reason for the high energy transfer efficiency. The critical distance of the energy transfer has also been calculated by the concentration-quenching method. These results indicate that the Ca 2Al 3O 6F:Ce 3+,Tb 3+ phosphors have potential applications as a near UV-convertible phosphor for white light-emitting diodes because of its broad excitation in the near-ultraviolet range and the efficient green emission light. © 2012 American Chemical Society.

Liu C.-S.,National Taiwan University
Engineering Analysis with Boundary Elements | Year: 2014

In the present paper, the inverse Cauchy problems of Laplace equation and biharmonic equation are transformed, by using the method of fundamental solutions (MFS) and the Trefftz method (TM), to the systems of linear equations for determining the expansion coefficients. Then, we propose three different conditioners together with the conjugate gradient method (CGM) to solve the resultant ill-posed linear systems. They are the post-conditioning CGM and the pre-conditioning CGM based on the idea of equilibrated norm for the conditioned matrices, as well as a minimum-distance conditioner. These algorithms are convergent fast and accurate by solving the inverse Cauchy problems under random noise. © 2013 Elsevier Ltd.

Liu C.-S.,National Taiwan University
Engineering Analysis with Boundary Elements | Year: 2014

The method of fundamental solutions (MFS) is used to solve backward heat conduction problem, inverse heat source problem, inverse Cauchy problem and inverse Robin problem. In order to overcome the ill-posedness of resulting linear equations, two optimal algorithms with optimal descent vectors that consist of m vectors in a Krylov subspace are developed, of which the m weighting parameters are determined by minimizing a properly defined merit function in terms of a quadratic quotient. The optimal algorithms OA1 and OA2 are convergent fast, accurate and robust against large noise, which are confirmed through numerical tests. © 2014 Elsevier Ltd.

Tu Y.-K.,National Taiwan University
Medical Decision Making | Year: 2014

In the past decade, a new statistical method - network meta-analysis - has been developed to address limitations in traditional pairwise meta-analysis. Network meta-analysis incorporates all available evidence into a general statistical framework for comparisons of multiple treatments. Bayesian network meta-analysis, as proposed by Lu and Ades, also known as "mixed treatments comparisons," provides a flexible modeling framework to take into account complexity in the data structure. This article shows how to implement the Lu and Ades model in the frequentist generalized linear mixed model. Two examples are provided to demonstrate how centering the covariates for random effects estimation within each trial can yield correct estimation of random effects. Moreover, under the correct specification for random effects estimation, the dummy coding and contrast basic parameter coding schemes will yield the same results. It is straightforward to incorporate covariates, such as moderators and confounders, into the generalized linear mixed model to conduct meta-regression for multiple treatment comparisons. Moreover, this approach may be extended easily to other types of outcome variables, such as continuous, counts, and multinomial. © The Author(s) 2014.

The recent literature on high skilled labor migration has taken a turn from analyzing processes of 'brain drain' to processes of 'brain gain' and 'brain circulation'. Returning scientists, having been affiliated to foreign institutes, are able to facilitate knowledge exchanges between the two locations, and facilitate the linkage of the national scientific community to international scientific cooperation projects. In this way, return scientists can have a disproportionate impact on the development of the scientific community in their country of origin. However, not all flows of return migrants have had such a positive impact. Returnees failed to affect developments in some localities, while producing ambiguous effects in others. These studies typically argue that the impact of return migrants is dependent on the absorptive capacity and the local social, cultural, and institutional context in the country of origin. Using data on return migrants within the Taiwanese economic academic community, this paper seeks to add to this literature by arguing that the impact of return migrants is not only dependent on the circumstances in their country of origin, but is also contingent on the nature and quality of the context in which they acquired their international labor experience. Skills and access to knowledge networks are heterogeneously spread over geographical space, so that the context in which a return migrant acquired his or her international labor experience matters. © 2012 Akadémiai Kiadó, Budapest, Hungary.

Wong K.-T.,National Taiwan University | Bassani D.M.,CNRS Institute of Molecular Sciences
NPG Asia Materials | Year: 2014

Supramolecular materials use self-assembly of molecular components to form complex architectures that may otherwise be extremely difficult to prepare. One of the fundamental aspects of this approach is that relatively weak intermolecular forces are used to direct the assembly of the subcomponents. An important point is how to achieve strong electronic communication throughout the material in view of the 'looseness' of the molecular constituents, which interact only weakly. This is particularly important for applications in molecular electronics where exciton delocalization and charge transport generally limit the overall device performance. This review focuses on recent advances in supramolecular materials and architectures that are engineered to possess efficient energy transfer between the self-assembled component in view of new applications in photonics and electronics. © 2014 Nature Publishing Group All rights reserved.

Su H.-M.,National Taiwan University
Journal of Nutritional Biochemistry | Year: 2010

Docosahexaenoic acid (DHA, 22:6n-3) is specifically enriched in the brain and mainly anchored in the neuronal membrane, where it is involved in the maintenance of normal neurological function. Most DHA accumulation in the brain takes place during brain development in the perinatal period. However, hippocampal DHA levels decrease with age and in the brain disorder Alzheimer's disease (AD), and this decrease is associated with reduced hippocampal-dependent spatial learning memory ability. A potential mechanism is proposed by which the n-3 fatty acids DHA and eicosapentaenoic acid (20:5n-3) aid the development and maintenance of spatial learning memory performance. The developing brain or hippocampal neurons can synthesize and take up DHA and incorporate it into membrane phospholipids, especially phosphatidylethanolamine, resulting in enhanced neurite outgrowth, synaptogenesis and neurogenesis. Exposure to n-3 fatty acids enhances synaptic plasticity by increasing long-term potentiation and synaptic protein expression to increase the dendritic spine density, number of c-Fos-positive neurons and neurogenesis in the hippocampus for learning memory processing. In aged rats, n-3 fatty acid supplementation reverses age-related changes and maintains learning memory performance. n-3 fatty acids have anti-oxidative stress, anti-inflammation, and anti-apoptosis effects, leading to neuron protection in the aged, damaged, and AD brain. Retinoid signaling may be involved in the effects of DHA on learning memory performance. Estrogen has similar effects to n-3 fatty acids on hippocampal function. It would be interesting to know if there is any interaction between DHA and estrogen so as to provide a better strategy for the development and maintenance of learning memory. © 2010 Elsevier Inc.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Diabetes Care | Year: 2011

OBJECTIVE - The link between diabetes and prostate cancer is rarely studied in Asians. RESEARCH DESIGN AND METHODS - The trend of age-standardized prostate cancer incidence in 1995-2006 in the Taiwanese general population was calculated. A random sample of 1,000,000 subjects covered by the National Health Insurance in 2005 was recruited. A total of 494,630 men for all ages and 204,741 men ≥40 years old and without prostate cancer at the beginning of 2003 were followed to the end of 2005. Cumulative incidence and risk ratio between diabetic and nondiabetic men were calculated. Logistic regression estimated the adjusted odds ratios for risk factors. RESULTS - The trend of prostate cancer incidence increased significantly (P < 0.0001). The cumulative incidence markedly increased with age in either the diabetic or nondiabeticmen. The respective risk ratio (95% CI) for all ages and age 40-64, 65-74, and ≥75 years was 5.83 (5.10-6.66), 2.09 (1.60-2.74), 1.35 (1.07-1.71), and 1.39 (1.12-1.71). In logistic regression for all ages or for age ≥40 years, age, diabetes, nephropathy, ischemic heart disease, dyslipidemia, living region, and occupation were significantly associated with increased risk, but medications including insulin and oral antidiabetic agents were not. CONCLUSIONS - Prostate cancer incidence is increasing in Taiwan. A positive link between diabetes and prostate cancer is observed, which is more remarkable in the youngest age of 40-64 years. The association between prostate cancer and comorbidities commonly seen in diabetic patients suggests amore complicated scenario in the link between prostate cancer and diabetes at different disease stages. © 2011 by the American Diabetes Association.

Tao W.-K.,NASA | Chen J.-P.,National Taiwan University | Li Z.,The Interdisciplinary Center | Li Z.,Beijing Normal University | And 2 more authors.
Reviews of Geophysics | Year: 2012

Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosol effects on clouds could further extend to precipitation, both through the formation of cloud particles and by exerting persistent radiative forcing on the climate system that disturbs dynamics. However, the various mechanisms behind these effects, in particular, the ones connected to precipitation, are not yet well understood. The atmospheric and climate communities have long been working to gain a better grasp of these critical effects and hence to reduce the significant uncertainties in climate prediction resulting from such a lack of adequate knowledge. Here we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes from theoretical analysis of microphysics, observational evidence, and a range of numerical model simulations. In addition, the discrepancies between results simulated by models, as well as those between simulations and observations, are presented. Specifically, this paper addresses the following topics: (1) fundamental theories of aerosol effects on microphysics and precipitation processes, (2) observational evidence of the effect of aerosols on precipitation processes, (3) signatures of the aerosol impact on precipitation from large-scale analyses, (4) results from cloud-resolving model simulations, and (5) results from large-scale numerical model simulations. Finally, several future research directions for gaining a better understanding of aerosol-cloud-precipitation interactions are suggested. Copyright 2012 by the American Geophysical Union.

Liu C.-S.,National Taiwan University
Engineering Analysis with Boundary Elements | Year: 2014

We consider an inverse heat source problem of a nonlinear heat conduction equation, for recovering an unknown space-dependent heat source under the Cauchy type boundary conditions. With the aid of measured initial temperature and initial heat flux, which are disturbanced by random noise causing measurement error, we develop a Lie-group differential algebraic equations (LGDAE) method to solve the resultant differential algebraic equations. The Lie-group numerical method has a stabilizing effect to retain the solution on the associated manifold, which thus naturally has a regularization effect to overcome the ill-posed property of the nonlinear inverse heat source problem. As a consequence, we can quickly recover the unknown heat source under noisy input data only through a few iterations. The initial data used in the recovery of heat source are assumed to be the analytic continuation ones which are not given arbitrarily. Certainly, the measured initial data belong to this type data. © 2014 Elsevier Ltd.

Capart H.,National Taiwan University
Water Resources Research | Year: 2013

An analytical model is proposed to describe lake drainage and downstream flooding due to the gradual breaching of natural and manmade earthen dams. Erodible triangular dams are considered, undergoing gradual incision by a breaching channel of constant effective width. Adopting a simple stream power law for dam material transport, the long profile evolution of the breaching channel is governed by a diffusion equation with variable diffusion rate, proportional to the water discharge. The resulting flood is routed downstream using the kinematic wave equation. Moving boundary problems are obtained due to retrogression of the breach crest, and to the downstream propagation of the flood wavefront. For both the dam breaching and flood routing problems, explicit analytical solutions are derived. They depict a breaching process that is at first self-accelerating, then becomes self-limiting. Results include boundary paths, long profiles, and stage and discharge hydrographs. In particular, the breaching solution yields a discharge hydrograph of simple analytical shape that turns out to be ideally suited for kinematic wave routing. The model is applied to the well-documented breaching of the Tangjiashan landslide dam, Sichuan, in June 2008. Calculated results for this and other cases are in reasonably good agreement with the measured data. As the model is simple to apply, with minimal computational and data requirements, it could prove useful as a tool for rapid risk assessment. The proposed analytical approach also complements numerical models by providing more transparent links between solution outcomes and the problem data. ©2013. American Geophysical Union. All Rights Reserved.

Hong B.-C.,National Chung Cheng University | Hsu C.-S.,National Chung Cheng University | Lee G.-H.,National Taiwan University
Chemical Communications | Year: 2012

A concise and practical enantioselective synthesis of (+)-galbulin has been achieved using organocatalytic domino Michael-Michael-aldol condensation and organocatalytic kinetic resolution as the key steps. This journal is © The Royal Society of Chemistry 2012.

Many chemicals commonly occurring in surface water are found to be hormonally active. Fourteen compounds including four sex hormones, three synthetic hormones, one non-steroidal anti-androgen, and six industrial endocrine-disrupting chemicals were selected to examine their acute toxicities on the freshwater planarian, Dugesia japonica. Among all test chemicals, diethylstilbestrol had the highest toxicity. Relatively, the toxicities of the synthetic hormones were higher than the natural ones. Among the six industrial endocrine-disrupting chemicals tested, bisphenol A was the most toxic, with a 48-h LC50 of 8.3 mg L-1. Overall, the natural or synthetic hormones, other than estrone and estriol, were more acutely toxic to planarians than the industrial endocrine disruptors tested. The acute toxicities of the test chemicals to Dugesia japonica were in the same order of magnitude as those to Daphnia magna based on available published data. Despite this study used non-environmentally relevant levels, such kinds of chemicals do not exist singly in the aquatic environment, but typically act in synergistic and/or additive ways in the complex environmental mixtures, and the total estrogen equivalents are much higher than a single chemical. This study stands as a starting point for other acute and chronic assays, namely using mixtures. © 2013 Taylor & Francis.

Miki T.,National Taiwan University | Miki T.,Ehime University | Miki T.,Kinki University
Proceedings. Biological sciences / The Royal Society | Year: 2014

Ecosystems have a limited buffering capacity of multiple ecosystem functions against biodiversity loss (i.e. low multifunctional redundancy). We developed a novel theoretical approach to evaluate multifunctional redundancy in a microbial community using the microbial genome database (MBGD) for comparative analysis. In order to fully implement functional information, we defined orthologue richness in a community, each of which is a functionally conservative evolutionary unit in genomes, as an index of community multifunctionality (MF). We constructed a graph of expected orthologue richness in a community (MF) as a function of species richness (SR), fit the power function to SR (i.e. MF = cSR(a)), and interpreted the higher exponent a as the lower multifunctional redundancy. Through a microcosm experiment, we confirmed that MF defined by orthologue richness could predict the actual multiple functions. We simulated random and non-random community assemblages using full genomic data of 478 prokaryotic species in the MBGD, and determined that the exponent in microbial communities ranged from 0.55 to 0.75. This exponent range provided a quantitative estimate that a 6.6-8.9% loss limit in SR occurred in a microbial community for an MF reduction no greater than 5%, suggesting a non-negligible initial loss effect of microbial diversity on MF.

Izumi K.,National Taiwan University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We analyze causal structures in Gauss-Bonnet gravity. It is known that Gauss-Bonnet gravity potentially has superluminal propagation of gravitons due to its noncanonical kinetic terms. In a theory with superluminal modes, an analysis of causality based on null curves makes no sense, and thus, we need to analyze them in a different way. In this paper, using the method of the characteristics, we analyze the causal structure in Gauss-Bonnet gravity. We have the result that, on a Killing horizon, gravitons can propagate in the null direction tangent to the Killing horizon. Therefore, a Killing horizon can be a causal edge as in the case of general relativity; i.e. a Killing horizon is the "event horizon" in the sense of causality. We also analyze causal structures on nonstationary solutions with (D-2)-dimensional maximal symmetry, including spherically symmetric and flat spaces. If the geometrical null energy condition, RABNANB≥0 for any null vector NA, is satisfied, the radial velocity of gravitons must be less than or equal to that of light. However, if the geometrical null energy condition is violated, gravitons can propagate faster than light. Hence, on an evaporating black hole where the geometrical null energy condition is expected not to hold, classical gravitons can escape from the "black hole" defined with null curves. That is, the causal structures become nontrivial. It may be one of the possible solutions for the information loss paradox of evaporating black holes. © 2014 American Physical Society.

Lin W.-Y.,National Taiwan University
PLoS ONE | Year: 2014

Biological evidence suggests that multiple causal variants in a gene may cluster physically. Variants within the same protein functional domain or gene regulatory element would locate in close proximity on the DNA sequence. However, spatial information of variants is usually not used in current rare variant association analyses. We here propose a clustering method (abbreviated as "CLUSTER"), which is extended from the adaptive combination of P-values. Our method combines the association signals of variants that are more likely to be causal. Furthermore, the statistic incorporates the spatial information of variants. With extensive simulations, we show that our method outperforms several commonly-used methods in many scenarios. To demonstrate its use in real data analyses, we also apply this CLUSTER test to the Dallas Heart Study data. CLUSTER is among the best methods when the effects of causal variants are all in the same direction. As variants located in close proximity are more likely to have similar impact on disease risk, CLUSTER is recommended for association testing of clustered rare causal variants in case-control studies. © 2014 Wan-Yu Lin.

Lambert N.,RIKEN | Chen Y.-N.,National Cheng Kung University | Cheng Y.-C.,National Taiwan University | Li C.-M.,National Cheng Kung University | And 3 more authors.
Nature Physics | Year: 2013

Recent evidence suggests that a variety of organisms may harness some of the unique features of quantum mechanics to gain a biological advantage. These features go beyond trivial quantum effects and may include harnessing quantum coherence on physiologically important timescales. In this brief review we summarize the latest results for non-trivial quantum effects in photosynthetic light harvesting, avian magnetoreception and several other candidates for functional quantum biology. We present both the evidence for and arguments against there being a functional role for quantum coherence in these systems. © 2013 Macmillan Publishers Limited.

Hou W.-S.,National Taiwan University
Chinese Journal of Physics | Year: 2012

Yukawa couplings of electroweak Goldstone bosons can be inferred from experiment, but the existence of an elementary Higgs boson is not yet an established fact. If a sequential chiral quark generation does exist, it would bring us now into the strong Yukawa coupling regime. Guided by a Bethe-Salpeter equation approach, we postulate that the leading collapse state, the (heavy) isotriplet and color-singlet π 1 meson, becomes the Goldstone boson G itself. Viewing it as a deeply bound state, a gap equation is constructed. This "bootstrap" picture for electroweak symmetry breaking relies on strong Yukawa coupling, without providing any theory of the latter. © 2012 The Physical Society of the Republic of China.

Shiau J.-T.,National Cheng Kung University | Wu F.-C.,National Taiwan University
Water Resources Research | Year: 2013

For reservoirs that are operated for multiple purposes such as water supply, flood control, and power generation, any attempts to incorporate environmental flow targets in the reservoir operation rules need to take into account both the human and ecosystem demands. To date, however, none of the reservoir operation schemes that consider environmental flow requirements includes subdaily flow regimes and is able to optimize for multiple reaches. Here, we address the temporal and spatial issues associated with the optimal environmental flow and operation strategies for a multipurpose reservoir system in Taiwan. We propose an environmental flow proportion strategy and three-period release approach, and multireach operation scenarios that simultaneously optimize reservoir performances and environmental flow objectives at subdaily to interannual timescales for a maximum of three connected reaches. Our results imply that taking into account the environmental flow objectives does not necessarily degrade the overall reservoir performance due to the positive effect on flood control, which in turn would compensate for the adverse effects on domestic water supply and hydropower generation. The three-period release approach benefits mainly the subdaily flow regime, while the environmental flow proportion strategy benefits primarily the daily flow regime. Spatially, a mutual exclusion is observed between the reaches above and below a diversion weir, a fact that revises the conventional perception that restoring the flow regimes of a downstream reach would automatically restore those of upstream reaches. An overall evaluation reveals that the three-reach scenario outperforms the two-reach scenarios, which then outperform the one-reach scenarios. The one- or two-reach scenario that incorporates the midstream reach may be taken as an alternative because such scenario would benefit the upstream or downstream reach in addition to the midstream reach. © 2013. American Geophysical Union. All Rights Reserved.

The present study is concerned with the recovery of an unknown initial condition for a one-dimensional heat conduction equation by using only the usual two boundary conditions of the direct problem for heat equation. The algorithm assumes a function for the unknown initial condition and derives an inverse problem for estimating a spatially-dependent heat source F(x) in T t(x, t) = Txx(x, t) + F(x). A self-adaptive Lie-group shooting method, namely a Lie-group adaptive method (LGAM), is developed to find F(x), and then by integrations or by solving a linear system we can extract the information for unknown initial condition. The new method possesses twofold advantages in that no a priori information of unknown functions is required and no extra data are needed. The accuracy and efficiency of present method are confirmed by comparing the estimated results with some exact solutions. © 2010 Elsevier Ltd. All rights reserved.

Wen W.-Y.,Chung Yuan Christian University | Wen W.-Y.,National Taiwan University | Wu S.-Y.,National Chiao Tung University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

In this Letter, we study the dipole coupling effect of holographic fermion in a charged dilatonic black hole proposed by Gubser and Rocha (2010) [1]. It is found that the property of Fermi liquid is rigid under perturbation of dipole coupling, and the Fermi momentum is linearly shifted. A gap is dynamically generated as the coupling becomes large enough and the Fermi surface ceases to exist as the bulk dipole coupling further increases. © 2012 Elsevier B.V.

Lin C.-S.,National Taiwan University | Yan S.,University of New England of Australia
Archive for Rational Mechanics and Analysis | Year: 2013

We study the existence of bubbling solutions for the the following Chern-Simons-Higgs equation: where Ω is a torus. If k = 1, for any critical point q of the associated sum of the Green functions, we introduce a quantity D(q) (see (1.11) below). We show that for any non-degenerate critical point q with D(q) < 0, the above problem has a solution uε satisfying that ε → 0, uε blows up at q. The calculations in this paper also show that, if a sequence of solutions uε blows up at q as ε → 0, then q must be a critical point of the associated sum of the Green functions, and D (q) ≤ 0. So, the condition D(q) < 0 is almost necessary to obtain our result. We also construct solutions with k bubbles for k ≥ 2. © 2012 Springer-Verlag.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Journal of Environmental Science and Health - Part C Environmental Carcinogenesis and Ecotoxicology Reviews | Year: 2014

There is a concern of an increased risk of bladder cancer associated with the use of thiazolidinediones, a class of oral glucose-lowering drugs commonly used in patients with type 2 diabetes with a mechanism of improving insulin resistance. Human studies on related issues are reviewed, followed by a discussion on potential concerns on the causal inference in current studies. Pioglitazone and rosiglitazone are discussed separately, and findings from different geographical regions are presented. Randomized controlled trials designed for primarily answering such a cancer link are lacking, and evidence from clinical trials with available data for evaluating the association may not be informative. Observational studies have been reported with the use of population-based administrative databases, single-hospital records, drug adverse event reporting system, and case series collection. Meta-analysis has also been performed by six different groups of investigators. These studies showed a signal of higher risk of bladder cancer associated with pioglitazone, especially at a higher cumulative dose or after prolonged exposure; however, a weaker signal or null association is observed with rosiglitazone. In addition, there are some concerns on the causal inference, which may be related to the use of secondary databases, biases in sampling, differential detection, and confounding by indications. Lack of full control of smoking and potential biases related to study designs and statistical approaches such as prevalent user bias and immortal time bias may be major limitations in some studies. Overlapping populations and opposing conclusions in studies using the same databases may be of concern and weaken the reported conclusions of the studies. Because randomized controlled trials are expensive and unethical in providing an answer to this cancer issue, observational studies are expected to be the main source in providing an answer in the future. Furthermore, international comparison studies using well-designed and uniform methodology to clarify the risk in specific sexes, ethnicities, and other subgroups and to evaluate the interaction with other environmental risk factors or medications will be helpful to identify patients at risk. © 2014 Copyright © Taylor & Francis Group, LLC.

Lin C.K.,National Taiwan University
Nucleic acids research | Year: 2013

Predicting binding sites of a transcription factor in the genome is an important, but challenging, issue in studying gene regulation. In the past decade, a large number of protein-DNA co-crystallized structures available in the Protein Data Bank have facilitated the understanding of interacting mechanisms between transcription factors and their binding sites. Recent studies have shown that both physics-based and knowledge-based potential functions can be applied to protein-DNA complex structures to deliver position weight matrices (PWMs) that are consistent with the experimental data. To further use the available structural models, the proposed Web server, PiDNA, aims at first constructing reliable PWMs by applying an atomic-level knowledge-based scoring function on numerous in silico mutated complex structures, and then using the PWM constructed by the structure models with small energy changes to predict the interaction between proteins and DNA sequences. With PiDNA, the users can easily predict the relative preference of all the DNA sequences with limited mutations from the native sequence co-crystallized in the model in a single run. More predictions on sequences with unlimited mutations can be realized by additional requests or file uploading. Three types of information can be downloaded after prediction: (i) the ranked list of mutated sequences, (ii) the PWM constructed by the favourable mutated structures, and (iii) any mutated protein-DNA complex structure models specified by the user. This study first shows that the constructed PWMs are similar to the annotated PWMs collected from databases or literature. Second, the prediction accuracy of PiDNA in detecting relatively high-specificity sites is evaluated by comparing the ranked lists against in vitro experiments from protein-binding microarrays. Finally, PiDNA is shown to be able to select the experimentally validated binding sites from 10,000 random sites with high accuracy. With PiDNA, the users can design biological experiments based on the predicted sequence specificity and/or request mutated structure models for further protein design. As well, it is expected that PiDNA can be incorporated with chromatin immunoprecipitation data to refine large-scale inference of in vivo protein-DNA interactions. PiDNA is available at: http://dna.bime.ntu.edu.tw/pidna.

Li M.-H.,National Taiwan University
Toxicological and Environmental Chemistry | Year: 2012

Fourteen benzophenone-type UV filters and four paraben preservatives were selected to examine their acute toxicities on Dugesia japonica. The 48-h LC 50 values for planarians exposed to benzophenone-type UV filters can be ranked as oxybenzone > mexenone > 5-chloro-2-hydroxybenzophenone > 2,4-dihydroxybenzophenone > 2-hydroxybenzophenone > dioxybenzone > benzophenone > 2,2′,4,4′-tetrahydroxybenzophenone > 4-hydroxybenzophenone > 3-hydroxybenzophenone > 4,4′-dihydroxybenzophenone > 2,2′-dihydroxy-4,4′-dimethoxybenzophenone > 2,3,4-trihydroxybenzophenone > sulisobenzone with a range from 0.9 to 145 mg L -1 with a similar sequence for the 96 h LC 50 values, ranging from 0.5 to 77 mg L -1. The 48 and 96 LC 50 values for planarians exposed to paraben preservatives can be ranked as butylparaben > propylparaben > ethylparaben > methylparaben. Among all the tested chemicals, oxybenzone was the most toxic and sulisobenzone the least toxic chemical to planarian at each exposure period. Most benzophenone-type UV filters are toxic to aquatic animals with 48 h LC 50 values less than 10 mg L -1, except for 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,3,4-trihydroxybenzophenone, and sulisobenzone. Because of their common occurrence in aquatic environment, more studies on aquatic toxicities of benzophenone-type UV filters and paraben preservativs are needed to provide important information to adequately assess their ecological risk. © 2012 Taylor and Francis Group, LLC.

Ho P.-M.,National Taiwan University
Nuclear Physics B | Year: 2016

With the back-reaction of Hawking radiation taken into consideration, the work of Kawai, Matsuo and Yokokura [1] has shown that, under a few assumptions, the collapse of matter does not lead to event horizon nor apparent horizon. In this paper, we relax their assumptions and elaborate on the space-time geometry of a generic collapsing body with spherical symmetry. The geometry outside the collapsing sphere is found to be approximated by the geometry outside the white-hole horizon, hence the collapsing matter remains outside the Schwarzschild radius. As particles in Hawking radiation are created in the vicinity of the collapsing matter, the information loss paradox is alleviated. Assuming that the collapsing body evaporates within finite time, there is no event horizon. © 2016 The Author.

Viswanathan K.,National Taiwan University
Sensors and Actuators, A: Physical | Year: 2012

In this communication, the new, simple and sensitive fluorescent hybrid nanoparticles sensor has been designed for the copper ions detection. For this study, the fluorescent hybrid nanoparticles were synthesized by a single step approach and functionalized with tri peptide. And their size can range from about 70 to 75 nm in diameter. In the presence of copper ions, the imidazole rings of the histidine in tripeptide conjugated fluorescent hybrid nanoparticles can form six membered chelate rings complex, triggered energy transfer, and it leads fluorescence quenching. The results indicated that, minimum up to 0.5 μ of copper ion caused the fluorescence quenching with excellent selectivity response over other interferences at the micro gram level and the quenching kinetics also discussed. © 2011 Elsevier B.V. All rights reserved.

Hung L.-C.,National Taiwan University
Nonlinear Analysis: Real World Applications | Year: 2011

This paper is concerned with the existence of traveling front solutions for competitivecooperative LotkaVolterra systems of three species. By converting the system into a monotone system, we show that under certain assumptions on the parameters appearing in the system, traveling front solutions exist. Also, exact traveling front solutions, which are polynomials in the hyperbolic tangent function, are given explicitly in certain parameter regimes. © 2011 Elsevier Ltd. All rights reserved.

Wang Y.H.,National Taiwan University
Journal of biomedical optics | Year: 2012

This study investigates a photoacoustic/ultrasound dual-modality contrast agent, including extending its applications from image-contrast enhancement to combined diagnosis and therapy with site-specific targeting. The contrast agent comprises albumin-shelled microbubbles with encapsulated gold nanorods (AuMBs). The gas-filled microbubbles, whose diameters range from submicrometer to several micrometers, are not only echogenic but also can serve as drug-delivery vehicles. The gold nanorods are used to enhance the generation of both photoacoustic and photothermal signals. The optical absorption peak of the gold nanorods is tuned to 760 nm and is invariant after microbubble encapsulation. Dual-modality contrast enhancement is first described here, and the applications to cellular targeting and laser-induced thermotherapy in a phantom are demonstrated. Photoacoustic imaging can be used to monitor temperature increases during the treatment. The targeting capability of AuMBs was verified, and the temperature increased by 26°C for a laser power of 980 mW, demonstrating the potential of combined diagnosis and therapy with the dual-modality agent. Targeted photo- or acoustic-mediated delivery is also possible.

Chen C.-K.,National Taiwan University
Computer Methods and Programs in Biomedicine | Year: 2012

Correctly diagnosing the cancer stage is most important for selecting an appropriate cancer treatment option for a patient. Recent advances in microarray technology allow the cancer stage to be predicted using gene expression patterns. The cancer stage is in ordinal scale. In this paper, we employ strict ordinal regressions including cumulative logit model in traditional statistics with data dimensionality reduction, and distribution free approaches of large margin rank boundaries implemented by the support vector machine, as well as an ensemble ranking scheme to model the cancer stage using gene expression microarray data. Predictive genes included in models are selected by univariate feature ranking, and recursive feature elimination. We perform cross-validation experiments to assess and compare classification accuracies of ordinal and non-ordinal algorithms on five cancer stage microarray datasets. We conclude that a strict ordinal classifier trained by a validated approach can predict the cancer stage more accurately than traditional non-ordinal classifiers without considering the order of cancer stages. © 2012 Elsevier Ireland Ltd.

Wu C.-L.,Academia Sinica, Taiwan | Fu L.-C.,National Taiwan University
IEEE Transactions on Systems, Man, and Cybernetics: Systems | Year: 2012

The current smart home is a ubiquitous computing environment consisting of multiple autonomous spaces, and its advantage is that a service interacting with home users can be set with different configurations in space, hardware, software, and quality. As well as being smart technologically speaking, a smart home should also never forget to retain the "home nature" when it is serving its users. In this paper, we first analyze the relationship among services, spaces, and users, and then we propose a framework as well as a corresponding algorithm to model their interaction relationship. Later, we also realize the human-system interaction framework to implement a smart home system and develop "pervasive applications" to demonstrate how to utilize our framework to fulfill the human-centric interaction requirement of a smart home. Finally, our preliminary evaluations show that our proposed work can enhance the performance of the human-system interaction in a smart home environment. © 2006 IEEE.

Chai J.-D.,National Taiwan University
Journal of Chemical Physics | Year: 2012

In contrast to the original Kohn-Sham (KS) formalism, we propose a density functional theory (DFT) with fractional orbital occupations for the study of ground states of many-electron systems, wherein strong static correlation is shown to be described. Even at the simplest level represented by the local density approximation (LDA), our resulting DFT-LDA is shown to improve upon KS-LDA for multi-reference systems, such as dissociation of H 2 and N 2, and twisted ethylene, while performing similar to KS-LDA for single-reference systems, such as reaction energies and equilibrium geometries. Because of its computational efficiency (similar to KS-LDA), this DFT-LDA is applied to the study of the singlet-triplet energy gaps (ST gaps) of acenes, which are challenging problems for conventional electronic structure methods due to the presence of strong static correlation effects. Our calculated ST gaps are in good agreement with the existing experimental and high-level ab initio data. The ST gaps are shown to decrease monotonically with the increase of chain length, and become vanishingly small (within 0.1 kcal/mol) in the limit of an infinitely large polyacene. In addition, based on our calculated active orbital occupation numbers, the ground states for large acenes are shown to be polyradical singlets. © 2012 American Institute of Physics.

Chen M.-R.,National Taiwan University
Frontiers in Microbiology | Year: 2011

Host immune system is designed (or evolved) to fight against different pathogens. Many viruses infect the immune cells for the propagation of new progenies, thus the infection may modulate the host immune homeostasis. It has been more than 45 years since the discovery of Epstein-Barr virus (EBV) from a Burkitt's lymphoma derived cell line. The ability of EBV to transform primary B cells in vitro leads to the suggestion for its oncogenic potential. However, except the clear understanding of the role of EBV in post-transplantation lymphoproliferative disease, it remains ambiguous why such a ubiquitous virus causes malignant diseases only in a very small subset of individuals. Possible explanation is that EBV may cooperate with other environmental and host genetic factors and lead to the development of EBV associated neoplastic diseases. In addition to infecting B cells, recent studies revealed that EBV may impact host immune system more broadly than previously thought, for example the development of regulatory NKT subsets. Instead of an intensive review, this article aims to provide a linkage to recent advances on the interplay between EBV and host immune system and to inspire further studies on EBV related diseases, especially autoimmune diseases. © 2011 Chen.

Ao W.C.,University of Southern California | Chen K.-C.,National Taiwan University
IEEE Journal on Selected Areas in Communications | Year: 2012

Cognitive radio (CR) enables dynamic spectrum access to provide universal connectivity across different types of radio access technologies, realizing seamless content delivery in the next generation wireless networking. As the most general cognitive radio network scenario, multiple ad hoc and infrastructure networks sharing the same spectrum are allowed to cooperate with each other by using other networks' nodes as relays to carry and forward traffic, forming an interconnected heterogeneous network. Previous research is limited to the connectivity analysis of hybrid wireless networks with path loss channel model. In this paper, we analyze the connectivity of the interconnected heterogeneous network consisting of multiple ad hoc networks and multiple infrastructure networks from a percolation-based perspective, considering both noise-limited and interference-limited environment with general fading channel model. The benefit of network-based cooperation is quantified in terms of the percolation threshold, facilitating proper network control and deployment. For example, using such quantification, we can specify the amount of infrastructure deployment or reliable connections to control the connectivity of existing ad hoc networks, and vice versa. Finally, we apply the analysis to the coexistence of primary and secondary networks, as the common CR scenario. © 2012 IEEE.

Liu C.-S.,National Taiwan University
Computers, Materials and Continua | Year: 2012

In order to solve ill-posed linear inverse problems, we modify the Tikhonov regularization method by proposing three different preconditioners, such that the resultant linear systems are equivalent to the original one, without dropping out the regularized term on the right-hand side. As a consequence, the new regularization methods can retain both the regularization effect and the accuracy of solution. The preconditioned coefficient matrix is arranged to be equilibrated or diagonally dominated to derive the optimal scales in the introduced preconditioning matrix. Then we apply the iterative scheme to find the solution of ill-posed linear inverse problem. Two theorems are proved that the iterative sequences are monotonically convergent to the true solution. The presently proposed optimally generalized regularization methods are able to overcome the ill-posedness of linear inverse problems, and provide rather accurate numerical solution. Copyright © 2012 Tech Science Press.

Cheng M.Y.,National Taiwan University
Sensors (Basel, Switzerland) | Year: 2010

In this work, we present the development of a polymer-based capacitive sensing array. The proposed device is capable of measuring normal and shear forces, and can be easily realized by using micromachining techniques and flexible printed circuit board (FPCB) technologies. The sensing array consists of a polydimethlysiloxane (PDMS) structure and a FPCB. Each shear sensing element comprises four capacitive sensing cells arranged in a 2 × 2 array, and each capacitive sensing cell has two sensing electrodes and a common floating electrode. The sensing electrodes as well as the metal interconnect for signal scanning are implemented on the FPCB, while the floating electrodes are patterned on the PDMS structure. This design can effectively reduce the complexity of the capacitive structures, and thus makes the device highly manufacturable. The characteristics of the devices with different dimensions were measured and discussed. A scanning circuit was also designed and implemented. The measured maximum sensitivity is 1.67%/mN. The minimum resolvable force is 26 mN measured by the scanning circuit. The capacitance distributions induced by normal and shear forces were also successfully captured by the sensing array.

Chen K.-C.,National Taiwan University | Chiang M.,Princeton University | Poor H.V.,Princeton University
IEEE Journal on Selected Areas in Communications | Year: 2013

Social networks overlaid on technological networks account for a significant fraction of Internet use. Through graph theoretic and functionality models, this paper examines social network analysis and potential implications for the design of technological networks, and vice versa. Such interplay between social networks and technological networks suggests new directions for future research in networking. © 1983-2012 IEEE.

Wu P.-C.,National Pingtung University | Huang T.-W.,National Taiwan University
Assessment | Year: 2014

The Chinese version of Beck Depression Inventory II (BDI-II-C) is one of the most used instruments to measure the severity of depression in Taiwan. The scarce literature regarding its psychometric properties (e.g., measurement invariance) highlighted the need and significance for such an investigation. The purpose of this study was to examine the gender-related measurement invariance of the BDI-II-C in an adolescent sample facing an entrance examination in the following two ways: (a) examining configural, metric, and scalar invariance using multigroup confirmatory factor analyses and (b) estimating the effects of any detected noninvariance on mean differences. The participants included 827 (416 boys and 411 girls) Taiwanese adolescents. Results indicate that measurement invariance was established at the level of configural, metric, and partial scalar invariance. Seven noninvariant intercepts (Items 2, 3, 7, 9, 10, 12, and 19) were identified, showing that there was differential additive response style bias for the BDI-II-C across gender groups. Additionally, the results demonstrated that the noninvariance had significant effects on interpretation based on gender latent mean difference as well as observed mean difference. © The Author(s) 2012.

Chern R.-L.,National Taiwan University
Journal of the Optical Society of America B: Optical Physics | Year: 2014

The effect of damping on the Goos-Hänchen (GH) shift from weakly absorbing anisotropic metamaterials is investigated. Explicit formulas of the GH shifts are derived and analyzed at three particular angles of incidence: critical angle, pseudo-Brewster angle, and grazing incidence, near which the reflection phases exhibit strong variations and large GH shifts are likely to occur. The damping in the anisotropic metamaterials may result in GH shifts not available in ordinary isotropic media. In particular, a larger GH shift can be associated with a larger rather than a smaller damping, and a small change of damping may even reverse the direction of the GH shift near the pseudo-Brewster angle. This feature is characterized by a parabolic relation determined by the complex components of the permittivity tensor. The GH shifts are also illustrated with the incidence of Gaussian beams based on Fourier integral formulation. © 2014 Optical Society of America.

Tu Y.-K.,National Taiwan University | Tilling K.,University of Bristol | Sterne J.A.C.,University of Bristol | Gilthorp M.S.,University of Leeds
International Journal of Epidemiology | Year: 2013

The developmental origins of health and disease hypothesis suggests that small birth size in conjunction with rapid compensatory childhood growth might yield a greater risk of developing chronic diseases in later life. For example, there is evidence that people who developed coronary heart disease and diabetes experienced different growth trajectories from those who did not develop these diseases. However, some of the methods used in these articles may have been flawed. We critically evaluate proposed approaches for identifying the growth trajectories distinctive to those developing later disease and identifying critical phases of growth during the early lifecourse. Among the approaches we examined (tracing the z-scores, lifecourse plots and models, lifecourse path analysis, conditional body size analysis, multilevel analysis, latent growth curve models and growth mixture models) conditional body size analysis, multilevel analysis, latent growth curve models and growth mixture models are least prone to collinearity problems caused by repeated measures. Multilevel analysis is more flexible when body size is not measured at the same age for all cohort members. Strengths and weaknesses of each approach are illustrated using real data. Demonstrating the influence of growth trajectories on later disease is complex and challenging; therefore, it is likely that a combination of approaches will be required to unravel the complexity in lifecourse research. © The Author 2013; all rights reserved.

Lee W.-C.,National Taiwan University
American Journal of Epidemiology | Year: 2015

To detect gene-environment interactions, a logistic regression model is typically fitted to a set of case-control data, and the focus is on testing of the cross-product terms (gene × environment) in the model. A significant result is indicative of a gene-environment interaction under a multiplicative model for disease odds. Based on the sufficient-cause model for rates, in this paper we put forward a general approach to testing for sufficient-cause gene-environment interactions in case-control studies. The proposed tests can be tailored to detect a particular type of sufficient-cause gene-environment interaction with greater sensitivity. These tests include testing for autosomal dominant, autosomal recessive, and gene-dosage interactions. The tests can also detect trend interactions (e.g., a larger gene-environment interaction with a higher level of environmental exposure) and threshold interactions (e.g., gene-environment interaction occurs only when environmental exposure reaches a certain threshold level). Two assumptions are necessary for the validity of the tests: 1) the rare-disease assumption and 2) the no-redundancy assumption. Another 2 assumptions are optional but, if imposed correctly, can boost the statistical powers of the tests: 3) the gene-environment independence assumption and 4) the Hardy-Weinberg equilibrium assumption. SAS code (SAS Institute, Inc., Cary, North Carolina) for implementing the methods is provided. © 2015 The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved.

Chern C.-H.,National Taiwan University
Annals of Physics | Year: 2014

Pseudogap formation is a ubiquitous phenomenon in strongly-correlated superconductors, for example cuprates, heavy-fermion superconductors, and iron pnictides. As the system is cooled, an energy gap opens in the excitation spectrum before entering the superconducting phase. The origin of formation and the relevancy to the superconductivity remain unclear, which is the most challenging problem in condensed matter physics. Here, using the cuprate as a model, we demonstrate that the formation of pseudogap is due to a massive gauge interaction between electrons, where the mass of the gauge boson, determining the interaction length scale, is the consequence of the remnant antiferromagnetic fluctuation inherited from the parent compounds. Extracting from experimental data, we predict that there is a quantum phase transition belonging to the 2D XY universality class at the critical doping where pseudogap transition vanishes. © 2014 Elsevier Inc.

Jin F.-F.,University of Hawaii at Manoa | Jin F.-F.,Chinese Meteorological Agency | Boucharel J.,University of Hawaii at Manoa | Lin I.-I.,National Taiwan University
Nature | Year: 2014

The El Ninõ Southern Oscillation (ENSO) creates strong variations in sea surface temperature in the eastern equatorial Pacific, leading to major climatic and societal impacts1,2. In particular, ENSO influences the yearly variations of tropical cyclone (TC) activities in both the Pacific and Atlantic basins through atmospheric dynamical factors such as vertical wind shear and stability3-6. Until recently, however, the direct ocean thermal control of ENSOon TCs has not been taken into consideration because of an apparent mismatch in both timing and location: ENSOpeaks in winter and its surface warming occurs mostly along the Equator, a region without TC activity. Here weshowthat El Ninõ-the warmphase of anENSOcycle-effectively discharges heat into the eastern North Pacific basin two to three seasons after its wintertime peak, leading to intensified TCs. This basin is characterized by abundant TC activity and is the second most activeTCregionintheworld 5-7.As a result of the time involved inocean transport, El Ninõ's equatorial subsurface 'heat reservoir', built up in boreal winter, appears in the easternNorth Pacific severalmonths later during peakTCseason (boreal summer and autumn). Bymeans of this delayed ocean transport mechanism, ENSO provides an additional heat supply favourable for the formation of strong hurricanes. This thermal control on intenseTCvariability has significant implications for seasonal predictions and long-term projections ofTCactivity over the eastern North Pacific. © 2014 Macmillan Publishers Limited. All rights reserved.

Konar C.,National Taiwan University | Hardcastle M.J.,University of Hertfordshire
Monthly Notices of the Royal Astronomical Society | Year: 2013

In this paper, we showthat a small sample of radio galaxies with evidence for multiple epochs of jet activity (so-called double-double radio galaxies) have the same electron injection spectral index in the two activity episodes, a result which might be considered surprising given the very different lobe dynamics expected in the first and second episode. We construct models for the dynamics of radio galaxies, with an emphasis on their episodic behaviour, and show that hotspot formation and confinement of lobes for the inner double of double-double radio galaxies are possible even without any thermal matter in the outer cocoon. We argue that (i) the observed similar injection spectral indices are due to similar jet powers in the two episodes, (ii) the 'spectral index-radio power' correlation of a flux limited sample of radio galaxies is the primary one, and not the 'spectral index-redshift correlation', (iii) jets are made of pair plasma and not electron-proton and (iv) the Lorentz factor of the spine of the jet should be ≳10 to explain the observations. Furthermore, we argue that the observations show that higher power radio galaxies do not have a higher jet bulk Lorentz factors, but instead simply have a higher number density of particles in the jet rest frame. A consequence of our models is that aligned double-double radio galaxies with very old (≳108 yr) outer doubles, or misaligned double-double radio galaxies, are statistically more likely to have dissimilar injection indices in two different episodes, as they will probably have different jet powers. © 2013 The Authors.Published by Oxford University Press on behalf of the Royal Astronomical Society.

Yang C.-A.,China Medical University at Taichung | Chiang B.-L.,National Taiwan University Hospital | Chiang B.-L.,National Taiwan University
Journal of Autoimmunity | Year: 2015

Inflammasomes are multi-protein complexes composed of a NOD-like receptor (NLR)/an AIM-like receptor (ALR), the adapter molecule apoptosis-associated speck-like protein that contains a CARD (ASC), and caspase-1. Active caspase-1 cleaves pro-IL-1β and pro-IL-18 to IL-1β and IL-18, resulting in inflammation. Genetic mutations in inflammasomes were first recognized to result in autoinflammatory diseases, which are characterized by the absence of both autoantibodies and autoreactive-T/B cells. However, there is increasing attention being placed on genetic polymorphisms that are involved in the components of inflammasomes, and these have implications for innate immunity and the natural history of autoimmune diseases. For example, while the NOD-like receptor family, pyrin domain containing 1 (NLRP1) haplotypes contributes to susceptibility to developing vitiligo; there are other single nucleotide polymorphisms (SNPs) that alters the susceptibility and severity of rheumatoid arthritis (RA) and juvenile idiopathic arthritis. Indeed, there are multiple factors that contribute to lowering the threshold of immunity and inflammasomes play a key role in this threshold. For example, IL-1β and IL-18 further perpetuate Th17 responses and endothelial cell damage, which potentiate a number of autoimmune diseases, including synovitis in RA, cardiovascular disease, and systemic lupus erythematosus (SLE). There is also increasing data on the role of innate immunity in experimental autoimmune encephalomyelitis (EAE), in lupus nephritis, and in a variety of autoimmune pathologies in which activation of the innate immune system is the driver for the adaptive system. Indeed, it is likely that the chronic pathology of autoimmunity is mediated in part by otherwise innocent bystander cells, augmented by inflammasomes. © 2015 Elsevier Ltd.

A recent collection of African electric fish of the genus Petrocephalus from the Bangweulu-Mweru ecoregion of the Congo basin comprises two endemic species, Petrocephalus squalostoma (Boulenger, 1915), which was previously known only from its type specimens and another specimen, and a new species described herein as Petrocephalus frielisp. nov. An exclusive set of morphological characters distinguishes P. frieli sp. nov. from P. squalostoma and all other species of Petrocephalus from the Congo basin. Petrocephalus frieli sp. nov. can further be distinguished from the East African Petrocephalus catostoma catostoma (Günther, 1866) in having only 12 circumpenduncular scales (versus 15/16 in P. c. catostoma). A molecular phylogenetic analysis confirms the distinctiveness of P. squalostoma and P. frieli sp. nov. among a sampling of 18 species of Petrocephalus. Previous reports of Petrocephalus simus Sauvage, 1879 from the Bangweulu-Mweru ecoregion probably represent misidentifications and the occurrence of P. c. catostoma is not confirmed. © 2012 Copyright Taylor and Francis Group, LLC.

Tseng C.-H.,National Taiwan University | Tseng C.-H.,National Taiwan University Hospital
Atherosclerosis | Year: 2013

Objective: To investigate associations between body mass index (BMI) and cause-specific mortality in patients with type 2 diabetes mellitus (T2DM). Methods: Prospective follow-up of a nationally representative cohort of 89,056 Taiwanese patients with T2DM recruited since 1995. Vital status was matched with the National Death Certificate Database until the end of 2006. Self-reported body weight and height were used to calculate BMI, which was treated either as a continuous or categorical variable (underweight, <18.5; normal, 18.5-22.9; overweight, 23.0-24.9; obesity I, 25.0-29.9; and obesity II, ≥30.0 kg/m2). Causes of death were classified as all-cause, cancer, diabetes complications (macrovascular and microvascular), and other. Cox regression was used to estimate the hazard ratios. Results: A total of 26,951 patients (30.3% of the cohort) died during follow-up (cancer 5.4%, diabetes complications 17.4%, and other causes 7.5%). As a continuous variable, BMI was inversely associated with mortality from all-cause, cancer, diabetes complications, and other causes, with respective adjusted hazard ratios (95% confidence intervals) of 0.942 (0.939-0.946), 0.966 (0.958-0.975), 0.935 (0.930-0.939), and 0.942 (0.935-0.949). Compared to normal weight, underweight was significantly predictive for any of causes of death, while overweight, obesity I, and obesity II were all significantly associated with mortality in an inverse pattern. After excluding patients with a follow-up duration <2 years, most BMI categories were not significantly predictive of mortality from cancer, suggesting a potential bias of cancer-induced weight loss. Conclusions: The obesity paradox, mainly observed in noncancer mortality, exists in patients with T2DM, suggesting a survival advantage in obese diabetic patients. © 2012 Elsevier Ireland Ltd.

Han Y.-S.,National Taiwan University
Marine Biology | Year: 2011

Japanese eels spawn mainly during June-August. The larvae (leptocephali) then drift for 3-5 months before metamorphosing into glass eels. The recruitment season generally starts in southern East Asia in November and in northern areas in April the following year, a lag of ~5 months. However, analysis of otolith daily growth rings revealed only a 1-2-month difference in the mean leptocephalus stage between southern and northern East Asian samples. Experiments and field observation indicate that glass eels may starve, lose body weight, and remain in early pigmentation stage for a few months in cold waters. The time lag in recruitment can be accounted for by a longer leptocephalus stage combined with a low temperature-driven delay to upstream migration in winter. The leptocephalus duration and oceanic currents determine the dispersal locations up to the glass eel phase, while temperatures determine the timing of upstream migration time at each location. © 2011 Springer-Verlag.

Liaw J.-W.,Chang Gung University | Tsai H.-Y.,National Taiwan University
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2012

The plasmonic enhancement or quenching effects of a silica-coated gold nanorod (GNR@SiO 2) on the fluorescence of a molecule doped in the silica layer are studied using the multiple multipole method. The enhancement factors (EF) of a GNR with a typical aspect ratio of 3 coated by a 13nm silica layer upon the fluorescence of a molecule embedded at different locations with various orientations irradiated by a plane wave are analyzed, particularly at the longitudinal surface plasmon resonance (SPR) of GNR. The numerical results show that the EF of a GNR@SiO 2 on the fluorescence is sensitive to the molecular location and orientation. Furthermore, an effective EF (EEF), which is an average of EF over all possible orientations at a specific location, is calculated. According to EEF, the proximities of the end-caps of a GNR are strong enhancing zones. In contrast, the waist area is the weak zone. Moreover, a bigger GNR (a=10nm) possesses a higher EEF than a smaller one (a=7nm) for the same aspect ratio and the molecular relative location. Hence, a strong enhancement on the fluorescence is obtained using bigger GNR, if the molecule is near the end-cup and the dipole orientation is along the long axis. On the contrary, the consequence could be quenching, if the molecule is near the waist of a small GNR. The Stokes shift of fluorescence can also affect the EF, except the excitation wavelength. © 2012 Elsevier Ltd.

Liu C.-S.,National Taiwan University
International Journal of Heat and Mass Transfer | Year: 2011

We consider two typical inverse Stefan problems: one is computing a heat flux boundary condition when the moving boundary ξ(t) is given, and another is recovering an unknown moving boundary ξ(t), by knowing an extra Dirichlet boundary condition on the accessible boundary. Through a domain embedding method, we can transform the inverse problem into a parameter identification problem of an advection-diffusion partial differential equation, where ξ(t) and ξ̇(t) play the role of unknown parameters for the second inverse problem. The ξ̇(t) appeared in the governing equation makes the identification of ξ(t) rather difficult. However, upon using the Lie-group shooting method (LGSM) we can derive a simple system of algebraic equations to iteratively calculate ξ̇(t) and then ξ(t) at some discretized times. It is demonstrated through numerical examples that the LGSM is accurate and stable, although under a large measurement noise. © 2011 Elsevier Ltd. All rights reserved.

Sotskov Yu.N.,United Institute of Informatics Problems | Lai T.-C.,National Taiwan University
Computers and Operations Research | Year: 2012

We consider an uncertain single-machine scheduling problem, in which the processing time of a job can take any real value on a given closed interval. The criterion is to minimize the total weighted flow time of the n jobs, where there is a weight associated with a job. We calculate a number of minimal dominant sets of the job permutations (a minimal dominant set contains at least one optimal permutation for each possible scenario). We introduce a new stability measure of a job permutation (a stability box) and derive an exact formula for the stability box, which runs in O(n log n) time. We investigate properties of a stability box. These properties allow us to develop an O(n 2)-algorithm for constructing a permutation with the largest volume of a stability box. If several permutations have the largest volume of a stability box, the developed algorithm selects one of them due to a simple heuristic. The efficiency of the constructed permutation is demonstrated on a large set of randomly generated instances with 10≤n≤1000. © 2011 Elsevier Ltd. All rights reserved.

Huang C.-Y.,National Taiwan University | Anderegg W.R.L.,Stanford University | Anderegg W.R.L.,Carnegie Institution for Science
Global Change Biology | Year: 2012

Widespread drought-induced forest mortality has been documented across multiple tree species in North America in recent decades, but it is a poorly understood component in terrestrial carbon (C) budgets. Recent severe drought in concert with elevated temperature likely triggered widespread forest mortality of trembling aspen (Populus tremuloides), the most widely distributed tree species in North America. The impact on the regional C budgets and spatial pattern of this drought-induced tree mortality, which has been termed 'sudden aspen decline (SAD)', is not well known and could contribute to increased regional C emissions, an amplifying feedback to climate change. We conducted a regional assessment of drought-induced live aboveground biomass (AGB) loss from SAD across 915 km 2 of southwestern Colorado, USA, and investigated the influence of topography on the severity of mortality by combining field measures, remotely sensed nonphotosynthetically active vegetation and a digital elevation model. Mean [± standard deviation (SD)] remote sensing estimate of live AGB loss was 60.3 ± 37.3 Mg ha -1, which was 30.7% of field measured AGB, totaling 2.7 Tg of potential C emissions from this dieback event. Aspen forest health could be generally categorized as healthy (0-30% field measured canopy dieback), intermediate (31-50%), and SAD (51-100%), with the remote sensing estimated mean (± SD) live AGB losses of 26.4 ± 15.1, 64.5 ± 9.2, and 108.5 ± 24.0 Mg ha -1, respectively. There was a pronounced clustering pattern of SAD on south-facing slopes due to relatively drier and warmer conditions, but no apparent spatial gradient was found for elevation and slope. This study demonstrates the feasibility of utilizing remote sensing to assess the ramification of climate-induced forest mortality on ecosystems and suggests promising opportunities for systematic large-scale C dynamics monitoring of tree dieback, which would improve estimates of C budgets of North America with climate change. © 2011 Blackwell Publishing Ltd.

Kanemura S.,University of Toyama | Yokoya H.,University of Toyama | Zheng Y.-J.,National Taiwan University