Showing papers by "National University of Singapore published in 1999"
TL;DR: Caspase-3 is essential for certain processes associated with the dismantling of the cell and the formation of apoptotic bodies, but it may also function before or at the stage when commitment to loss of cell viability is made.
Abstract: Caspases are crucial mediators of programmed cell death (apoptosis). Among them, caspase-3 is a frequently activated death protease, catalyzing the specific cleavage of many key cellular proteins. However, the specific requirements of this (or any other) caspase in apoptosis have remained largely unknown until now. Pathways to caspase-3 activation have been identified that are either dependent on or independent of mitochondrial cytochrome c release and caspase-9 function. Caspase-3 is essential for normal brain development and is important or essential in other apoptotic scenarios in a remarkable tissue-, cell type- or death stimulus-specific manner. Caspase-3 is also required for some typical hallmarks of apoptosis, and is indispensable for apoptotic chromatin condensation and DNA fragmentation in all cell types examined. Thus, caspase-3 is essential for certain processes associated with the dismantling of the cell and the formation of apoptotic bodies, but it may also function before or at the stage when commitment to loss of cell viability is made.
3,259 citations
TL;DR: In this article, a MATLAB implementation of infeasible path-following algorithms for solving standard semidefinite programs (SDP) is presented, and Mehrotra-type predictor-corrector variants are included.
Abstract: This software package is a MATLAB implementation of infeasible path-following algorithms for solving standard semidefinite programs (SDP). Mehrotra-type predictor-corrector variants are included. Analogous algorithms for the homogeneous formulation of the standard SDP are also implemented. Four types of search directions are available, namely, the AHO, HKM, NT, and GT directions. A few classes of SDP problems are included as well. Numerical results for these classes show that our algorithms are fairly efficient and robust on problems with dimensions of the order of a hundred.
1,618 citations
TL;DR: It was demonstrated that while perceived usefulness had consistently strong effects on all usage dimensions, perceived ease of use and perceived enjoyment affected each specific usage dimension differently.
Abstract: This study focuses on both intrinsic (i.e. perceived enjoyment) and extrinsic (i.e. perceived usefulness) motivation for the use of the Internet. An electronic Webpage survey was used to collect the data required for this study. A total of 1370 usable responses were obtained. Results indicated that local Internet users used the Internet mainly because they perceived the Internet to be more useful to their job tasks and secondarily, because it is enjoyable and easy to use. Findings demonstrated that while perceived usefulness had consistently strong effects on all usage dimensions (frequency of Internet usage, daily Internet usage and diversity of Internet usage), perceived ease of use and perceived enjoyment affected each specific usage dimension differently.
1,293 citations
VU University Amsterdam1, University of Pennsylvania2, University of Maryland, Baltimore3, Cornell University4, New Mexico State University5, Qatar Airways6, Louisiana Tech University7, Université du Québec8, Stockholm School of Economics9, University of Buenos Aires10, University of Alberta11, University of Indonesia12, University of Queensland13, Bellevue University14, London Business School15, Western Illinois University16, University of Memphis17, Fudan University18, Boğaziçi University19, University of Reading20, University of South Africa21, Athens University of Economics and Business22, Ludwig Maximilian University of Munich23, University of Calgary24, University of Burgundy25, National Sun Yat-sen University26, Hong Kong Polytechnic University27, Indian Institute of Management Ahmedabad28, City University of Hong Kong29, Lincoln University (New Zealand)30, University of Lethbridge31, Wayne State University32, University College Dublin33, Indiana University34, Kuwait University35, Technion – Israel Institute of Technology36, University of Giessen37, The Chinese University of Hong Kong38, University of Zurich39, Fordham University40, Complutense University of Madrid41, University of Nebraska–Lincoln42, INCAE Business School43, National University of Malaysia44, Opole University45, Hong Kong Baptist University46, Tbilisi State University47, Ohio State University48, University of Wrocław49, Alexandria University50, University of San Francisco51, Melbourne Business School52, Bentley University53, University of Los Andes54, I-Shou University55, Johannes Kepler University of Linz56, International Labour Organization57, Smith College58, Copenhagen Business School59, Chungnam National University60, National University of Singapore61, Tilburg University62, Hong Kong University of Science and Technology63, Thammasat University64, Sewanee: The University of the South65, FernUniversität Hagen66, Soochow University (Suzhou)67, University of St. Gallen68, Kumamoto University69
TL;DR: In this paper, the authors focus on culturally endorsed implicit theories of leadership (CLTs) and show that attributes associated with charismatic/transformational leadership will be universally endorsed as contributing to outstanding leadership.
Abstract: This study focuses on culturally endorsed implicit theories of leadership (CLTs). Although cross-cultural research emphasizes that different cultural groups likely have different conceptions of what leadership should entail, a controversial position is argued here: namely that attributes associated with charismatic/transformational leadership will be universally endorsed as contributing to outstanding leadership. This hypothesis was tested in 62 cultures as part of the Global Leadership and Organizational Behavior Effectiveness (GLOBE) Research Program. Universally endorsed leader attributes, as well as attributes that are universally seen as impediments to outstanding leadership and culturally contingent attributes are presented here. The results support the hypothesis that specific aspects of charismatic/transformational leadership are strongly and universally endorsed across cultures.
1,227 citations
TL;DR: The high hydrogen-uptake capacity of these systems may be derived from the special open-edged, layered structure of the carbon nanotubes made from methane, as well as the catalytic effect of alkali metals.
Abstract: Lithium- or potassium-doped carbon nanotubes can absorb approximately 20 or approximately 14 weight percent of hydrogen at moderate (200 degrees to 400 degrees C) or room temperatures, respectively, under ambient pressure. These values are greater than those of metal hydride and cryoadsorption systems. The hydrogen stored in the lithium- or potassium-doped carbon nanotubes can be released at higher temperatures, and the sorption-desorption cycle can be repeated with little decrease in the sorption capacity. The high hydrogen-uptake capacity of these systems may be derived from the special open-edged, layered structure of the carbon nanotubes made from methane, as well as the catalytic effect of alkali metals.
1,086 citations
TL;DR: An important area of future research will be elucidation of the reasons why levels of steady-state oxidative damage to DNA and lipids vary so much between individuals, and their predictive value for the later development of human disease.
Abstract: When life first evolved on Earth, there was little oxygen in the atmosphere. Evolution of antioxidant defences must have been closely associated with the evolution of photosynthesis and of O2-dependent electron transport mechanisms. Studies with mice lacking antioxidant defences confirm the important roles of MnSOD and transferrin in maintaining health, but show that glutathione peroxidase (GPX) and CuZnSOD are not essential for everyday life (at least in mice). Superoxide can be cytotoxic by several mechanisms: one is the formation of hydroxyl radicals. There is good evidence that OH* formation occurs in vivo. Other important antioxidants may include thioredoxin, and selenoproteins other than GPX. Nitric oxide may be an important antioxidant in the vascular system. Diet-derived antioxidants are important in maintaining human health, but recent studies employing "biomarkers" of oxidative DNA damage are questioning the "antioxidant" roles of beta-carotene and ascorbate. An important area of future research will be elucidation of the reasons why levels of steady-state oxidative damage to DNA and lipids vary so much between individuals, and their predictive value for the later development of human disease.
946 citations
TL;DR: In this paper, the authors examined the construct of sociocultural adaptation and described the development and refinement of its measurement, and performed psychometric analyses of the Sociocultural Adaptation Scale (SCAS) based on the compilation of data across a large number of sojourner samples.
866 citations
TL;DR: In this paper, the authors proposed that trust in a brand is important and is a key factor in the development of brand loyalty, and that marketers should take careful consideration of brand factors.
Abstract: Brands are important in the consumer market. They are the interface between consumers and the company, and consumers may develop loyalty to brands. This study proposes that trust in a brand is important and is a key factor in the development of brand loyalty. Factors hypothesized to influence trust in a brand include a number of brand characteristics, company characteristics and consumer-brand characteristics. Respondents representing a broad spectrum of Singapore consumers were surveyed. The findings reveal that brand characteristics are relatively more important in their effects on a consumer's trust in a brand. The results also show that trust in a brand is positively related to brand loyalty. Marketers should, therefore, take careful consideration of brand factors in the development of trust in a brand.
814 citations
TL;DR: The proposed definition of probiotics is based on the mechanisms of action, selection criteria, viability and non-viability, and scientifically documented health effects that will be discussed.
Abstract: Probiotics have been defined in several ways, depending on our understanding of the mechanisms of action of their effects on health and well-being of humans. The term probiotic was coined by Lilly and Stillwell [1] to describe substances produced by one microorganism, that stimulate the growth of another, thus meaning the opposite of antibiotics. Parker [2] subsequently defined probiotics as organisms and substances that contribute to intestinal balance. This definition, however, did not exclude antibiotics. At present, the most commonly used definition is that of Fuller [3] : Probiotics are live microbial feed supplements which beneficially affect the host animal by improving its intestinal microbial balance . Recently a European expert group widened the definition to include mechanisms other than just microflora mediated ones. The definition was as follows: Probiotics are live microbial food ingredients that have a beneficial effect on human health [4,5] . To include the current application and scientific data on proven effects of probiotics we propose the following definition: Probiotics are microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well-being of the host . This definition implies that probiotics do not necessarily need to be viable. Non-viable forms of probiotics have also been shown to have health effects [6] . The definition does not restrict the use of probiotics in foods; several other applications have been reported to have beneficial health effects. Not only whole microbial cells, but also parts of cells have been observed to improve host health. Metabolites are, however, not included in the current definition. Thus, it excludes antibiotics. The proposed definition is based on the mechanisms of action, selection criteria, viability and non-viability, and scientifically documented health effects that will be discussed.
777 citations
01 Aug 1999
TL;DR: This paper proposes a novel technique that allows the user to specify multiple minimum supports to reflect the natures of the items and their varied frequencies in the database and shows that the technique is very effective.
Abstract: Association rule mining is an important model in data mining. Its mining algorithms discover all item associations (or rules) in the data that satisfy the user-specified minimum support (minsup) and minimum confidence (minconf) constraints. Minsup controls the minimum number of data cases that a rule must cover. Minconf controls the predictive strength of the rule. Since only one minsup is used for the whole database, the model implicitly assumes that all items in the data are of the same nature and/or have similar frequencies in the data. This is, however, seldom the case in reallife applications. In many applications, some items appear very frequently in the data, while others rarely appear. If minsup is set too high, those rules that involve rare items will not be found. To find rules that involve both frequent and rare items, minsup has to be set very low. This may cause combinatorial explosion because those frequent items will be associated with one another in all possible ways. This dilemma is called the rare item problem. This paper proposes a novel technique to solve this problem. The technique allows the user to specify multiple minimum supports to reflect the natures of the items and their varied frequencies in the database. In rule mining, different rules may need to satisfy different minimum supports depending on what items are in the rules. Experiment results show that the technique is very effective.
749 citations
TL;DR: In this article, a study on the vibration of cylindrical shells made of a functionally gradient material (FGM) composed of stainless steel and nickel is presented, the objective is to study the natural frequencies, the influence of constituent volume fractions and the effects of configurations of the constituent materials on the frequencies.
TL;DR: In this article, three pellet samples with different grain sizes were obtained by annealing at high temperature and the room temperature Raman spectra of these samples show that as the grain size decreases, the Raman peaks shift to lower wavenumber and become broader owing to size effects.
Abstract: CuO nanoparticles were successfully prepared by a one-step solid-state reaction under ambient conditions. Three pellet samples with different grain sizes were obtained by annealing at high temperature. The room temperature Raman spectra of these samples show that as the grain size decreases, the Raman peaks shift to lower wavenumber and become broader owing to size effects. The dependences of the Raman spectra on the wavelength of the excitation laser and temperature were also investigated. Copyright © 1999 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors developed basic tools of calculus on time scales such as versions of Taylor's formula, l'Hospital's rule, and Kneser's theorem.
Abstract: The study of dynamic systems on time scales not only unifies continuous and discrete processes, but also helps in revealing diversities in the corresponding results. In this paper we shall develop basic tools of calculus on time scales such as versions of Taylor’s formula, l’Hospital’s rule, and Kneser’s theorem. Applications of these results in the study of asymptotic and oscillatory behavior of solutions of higher order equations on time scales are addressed. As a further application of Taylor’s formula, Abel-Gontscharoff interpolating polynomial on time scales is constructed and best possible error bounds are offered. We have also included notes at the end of each section which indicate further scope of the calculus developed in this paper.
TL;DR: In this paper, the authors used experimental design and conjoint analysis to study the risk perception of Singaporean consumers on Internet shopping, and tested the effectiveness of several risk-reducing strategies that Internet marketers could use in promoting online shopping among consumers.
Abstract: Using experimental design and conjoint analysis, this paper studies the risk perception of Singaporean consumers on Internet shopping, and tests the effectiveness of several risk‐reducing strategies that Internet marketers could use in promoting online shopping among consumers. The results show that Singaporean consumers with a higher degree of risk aversion than others tend to perceive Internet shopping to be a risky activity. However, Internet marketers could rely on using reference group appeal as the most preferred risk relievers for this group of consumers, particularly by getting expert users to endorse the products involved. In addition, the marketer’s reputation, the brand’s image, and specific warranty strategies are also effective risk relievers for the potential Internet shoppers.
TL;DR: The peak-to-average power ratio of an OFDM system and the optimal companding coefficient are determined and the symbol error rate of the systems after the companding is derived.
Abstract: A companding technique is proposed to reduce the peak-to-average-power ratio of the orthogonal frequency division multiplexing (OFDM) signal in this paper. The probability density function of the amplitude of the OFDM signal is determined. Because of the Gaussian distribution of the OFDM signal, the companding technique can be quite effective, since a large OFDM signal only occurs infrequently. The peak-to-average power ratio of an OFDM system and the optimal companding coefficient are determined in this paper. The symbol error rate of the systems after the companding is derived. The performances of the system with and without the companding are also compared.
TL;DR: This article summarizes recent progress and regulatory guidance on design of trials to assess the efficacy of new therapies for functional gastrointestinal disorders (FGIDs).
TL;DR: The present study clearly shows that DNA-damaged sperm (regardless of degree of damage) have the ability to fertilize the oocyte, but that embryonic development is very much related to the degree of DNA damage.
Abstract: In order to investigate the fertilizing ability of DNA-damaged sperm, they were exposed to gamma radiation prior to insemination. The presence of DNA-strand breaks were detected by the TUNEL test. Fertilization rates of 64.3, 59.9, 58.5, and 61.1% were achieved when sperm were subjected to 5, 10, 50, and 100 GY, respectively. This rate was 53.2% in the control group with no significant difference (P > 0.01). The blastocyst development was decreased from 49.8% in the control group to 20.3, 7.8, 3.4, and 2.3% with sperm exposed to doses of 5, 10, 50, and 100 GY, respectively. Of the transferred blastocyst in the control group, 69.8% were implanted and 33.9% developed into live fetuses. These rates were 57.1 and 21. 4%, 20 and 0% when sperm were exposed to doses of 5 and 10 GY with a significant difference (P < 0.01). The present study clearly shows that DNA-damaged sperm (regardless of degree of damage) have the ability to fertilize the oocyte, but that embryonic development is very much related to the degree of DNA damage. However, the oocyte has the capacity to repair DNA damage of sperm when it is damaged less than 8%. Damage beyond this level will result in low rate of embryonic development and high early pregnancy loss. J. Exp. Zool. 284:696-704, 1999.
TL;DR: The identification of a mutation, SPOROCYTELESS (SPL), which blocks sporocyte formation in Arabidopsis thaliana is reported, which suggests that development of the anther walls and the tapetum and microsporocytes formation are tightly coupled, and that nucellar development may be dependent on megasporocyte formation.
Abstract: The formation of haploid spores marks the initiation of the gametophytic phase of the life cycle of all vascular plants ranging from ferns to angiosperms. In angiosperms, this process is initiated by the differentiation of a subset of floral cells into sporocytes, which then undergo meiotic divisions to form microspores and megaspores. Currently, there is little information available regarding the genes and proteins that regulate this key step in plant reproduction. We report here the identification of a mutation, SPOROCYTELESS (SPL), which blocks sporocyte formation in Arabidopsis thaliana. Analysis of the SPL mutation suggests that development of the anther walls and the tapetum and microsporocyte formation are tightly coupled, and that nucellar development may be dependent on megasporocyte formation. Molecular cloning of the SPL gene showed that it encodes a novel nuclear protein related to MADS box transcription factors and that it is expressed during microsporogenesis and megasporogenesis. These data suggest that the SPL gene product is a transcriptional regulator of sporocyte development in Arabidopsis.
01 Aug 1999
TL;DR: The technique first prunes the discovered associations to remove those insignificant associations, and then finds a special subset of the unpruned associations to form a summary of the discovered association rules, which are then called the direction setting rules.
Abstract: Association rules are a fundamental class of patterns that exist in data. The key strength of association rule mining is its completeness. It finds all associations in the data that satisfy the user specified minimum support and minimum confidence constraints. This strength, however, comes with a major drawback. It often produces a huge number of associations. This is particularly true for data sets whose attributes are highly correlated. The huge number of associations makes it very diff icult, if not impossible, for a human user to analyze in order to identify those interesting/useful ones. In this paper, we propose a novel technique to overcome this problem. The technique first prunes the discovered associations to remove those insignificant associations, and then finds a special subset of the unpruned associations to form a summary of the discovered associations. We call this subset of associations the direction setting (DS) rules as they set the directions that are followed by the rest of the associations. Using this summary, the user can focus on the essential aspects (or relationships) of the domain and selectively view the relevant details. The approach is effective because experiment results show that the set of DS rules is typically very small . They can be analyzed manually by a human user. The proposed technique has also been applied successfully to a number of real-li fe applications.
TL;DR: The state of the art in audio information retrieval is reviewed, and recent advances in automatic speech recognition, word spotting, speaker and music identification, and audio similarity are presented with a view towards making audio less “opaque”.
Abstract: The problem of audio information retrieval is familiar to anyone who has returned from vacation to find ananswering machine full of messages. While there is not yetan "AltaVista" for the audio data type, many workers arefinding ways to automatically locate, index, and browse audio using recent advances in speech recognition and machinelistening. This paper reviews the state of the art in audioinformation retrieval, and presents recent advances in automatic speech recognition, word spotting, speaker and music identification, and audio similarity with a view towardsmaking audio less "opaque". A special section addresses intelligent interfaces for navigating and browsing audio andmultimedia documents, using automatically derived information to go beyond the tape recorder metaphor.
TL;DR: It is shown that queries formulated on shared views, export schema, and shared “ontologies” can be mediated in the same way using the Context Interchange framework.
Abstract: The Context Interchange strategy presents a novel perspective for mediated data access in which semantic conflicts among heterogeneous systems are not identified a priori, but are detected and reconciled by a context mediator through comparison of contexts axioms corresponding to the systems engaged in data exchange. In this article, we show that queries formulated on shared views, export schema, and shared “ontologies” can be mediated in the same way using the Context Interchange framework. The proposed framework provides a logic-based object-oriented formalsim for representing and reasoning about data semantics in disparate systems, and has been validated in a prototype implementation providing mediated data access to both traditional and web-based information sources.
TL;DR: It is reported that alternative splicing of the α1A subunit gene results in channels with distinct kinetic, pharmacological and modulatory properties, as well as multiple phenotypic variants.
Abstract: P-type and Q-type calcium channels mediate neurotransmitter release at many synapses in the mammalian nervous system. The α1A calcium channel has been implicated in the etiologies of conditions such as episodic ataxia, epilepsy and familial migraine, and shares several properties with native P- and Q-type channels. However, the exact relationship between α1A and P- and Q-type channels is unknown. Here we report that alternative splicing of the α1A subunit gene results in channels with distinct kinetic, pharmacological and modulatory properties. Overall, the results indicate that alternative splicing of the α1A gene generates P-type and Q-type channels as well as multiple phenotypic variants.
TL;DR: In this paper, a one-step solid state reaction method under ambient conditions was used to prepare monoclinic CuO nanoparticles by using a single-step reaction method and the particles with an average size of 12 nm were pressed into pellets under high pressure.
TL;DR: Carbon nanotubes prepared by catalytic (CO) disproportionation were studied using TEM, XRD, UPS, XPS, and optical spectroscopies in this paper.
Abstract: Carbon nanotubes prepared by catalytic (CO) disproportionation were studied using TEM, XRD, UPS, XPS, and optical spectroscopies. In comparison with graphite, the carbon nanotubes show greater interplanar distance, smaller work function, steeper Fermi edge, negative core-level shift, and stronger plasma excitation. Their valence band is basically the same as that of graphite, with lower intensity in the binding energy region of 2--7 eV. The carbon nanotubes exhibit a strong optical limiting effect, superior to both carbon black and ${\mathrm{C}}_{60}$.
TL;DR: In this paper, the Yamabe problem is reduced to find solutions of the following nonlinear elliptic equations, i.e., the problem of finding a metric g conformal to g0 such that k is the scalar curvature of the new metric g.
Abstract: Recently, there have been much analytic work on the conformally invariant operators as well as its associated differential equations. A well known second order conformally invariant operator comes from the Yamabe problem or, more generally, the problem of prescribed scalar curvature. Given a smooth positive function K defined on a compact Riemannian manifold (M, g0) of dimension n ≥ 2, we ask whether there exists a metric g conformal to g0 such that K is the scalar curvature of the new metric g. Let g = eg0 for n = 2 or g = u 4 n−2 g0 for n ≥ 3, then the problem is reduced to find solutions of the following nonlinear elliptic equations:
31 Oct 1999
TL;DR: This paper introduces AMRIS, a new multicast routing protocol for ad hoc wireless networks designed to operate independently of underlying unicast protocols and the results reported are simulated with PARSEC.
Abstract: This paper introduces AMRIS, a new multicast routing protocol for ad hoc wireless networks. AMRIS (Ad hoc Multicast Routing protocol utilizing Increasing id-numberS) is designed to operate independently of underlying unicast protocols. The idea behind AMRIS is to dynamically assign every node (on demand) in a multicast session with an id-number. The ordering between id-numbers is used to direct the multicast flow, and the sparseness among them used for quick connectivity repair. A multicast delivery tree rooted at a special node called Sid joins up the nodes participating in the multicast session. The relationship between the id-numbers (and the nodes that own them) and Sid is that the id-numbers increase in numerical value as they radiate from Sid in the delivery tree. These id-numbers help the nodes dynamically leave and join a session, as well as adapt rapidly to changes in link connectivity (due to mobility etc.). Messages to repair a link breakage are confined to the region where it occurs. AMRIS is simulated with PARSEC and the results reported.
TL;DR: The reduction in growth rate of T. castaneum larvae and S. zeamais adults was mainly due to a behavioural (feeding deterrent) action rather than to post-ingestive toxicity of the oil, and the essential oil had a weaker feeding deterrent action against E. rutaecarpa.
TL;DR: LiNi1−x−yCoxMnyO2 (0≤x≤0.5, 0≤y ≥ 0.3) samples with different x and y values show a pure phase of layered hexagonal structure as mentioned in this paper.
TL;DR: In this paper, a conceptual model is proposed that integrates the research on the environmental perspective of service experiences with the standard satisfaction model, and an experiment was conducted to test a part of this model.
01 Dec 1999
TL;DR: A novel control method for a general class of nonlinear systems using neural networks (NNs) under the conditions of the system output and its time derivatives being available for feedback, and an adaptive state feedback NN controller is developed.
Abstract: This paper presents a novel control method for a general class of nonlinear systems using neural networks (NNs). Firstly, under the conditions of the system output and its time derivatives being available for feedback, an adaptive state feedback NN controller is developed. When only the output is measurable, by using a high-gain observer to estimate the derivatives of the system output, an adaptive output feedback NN controller is proposed. The closed-loop system is proven to be semi-globally uniformly ultimately bounded (SGUUB). In addition, if the approximation accuracy of the neural networks is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussions.