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外语教学与研究 2001年第4期33卷 258-267页

作者： Ho Wah kam TheSingaporeTeachers'Union

This paper focuses on the upper end of the formal Singapore educational spectrum,providing an overview of ELT in polytechnics and universities. It is in four *** order to show continuity between ELT in schools and tertiary institutions,Part 1 explains briefly the nation’s language policy in *** Part 2,an attempt is made to delineate the main trends in ELT in universities and polytechnics and the approaches to ELT generally adopted for mature learners. Part 3 draws attention to the changing emphases in tertiary education in Singapore and to how students are being prepared in innovative ways in ELT for a globalised world and a knowledge based economy. Part 4 provides a summary of the paper.

关键词：英语教学高等院校教学方法语言交际能力

Enriched reproducing kernel particle method for fractional advection–diffusion equation

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Acta Mechanica Sinica 2018年第3期34卷 515-527页

作者： Yuping Ying Yanping Lian Shaoqiang Tang Wing kam Liu Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics College of Engineering Peking University Department of Mechanical Engineering Northwestern University HEDPS CAPT and LTCS Peking University

The reproducing kernel particle method （RKPM） has been efficiently applied to problems with large deformations, high gradients and high modal density. In this paper, it is extended to solve a nonlocal problem modeled by a fractional advectiondiffusion equation （FADE）, which exhibits a boundary layer with low regularity. We formulate this method on a moving least-square approach. Via the enrichment of fractional-order power functions to the traditional integer-order basis for RKPM, leading terms of the solution to the FADE can be exactly reproduced, which guarantees a good approximation to the boundary layer. Numerical tests are performed to verify the proposed approach.

关键词： Meshfree method Fractional calulus Enriched reproducing kernel Advection-diffusion equation Fractional-order basis

Joint timing and frequency synchronization in coherent optical OFDM systems

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Frontiers of Optoelectronics 2019年第1期12卷 4-14页

作者： Xinwei DU Pooi-Yuen kam Changyuan YU Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore National University of Singapore(Suzhou)Research Institute Suzhou 21512China Department of Electrical and Information Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

In this paper,we review our joint timing and frequency synchronization algorithms in coherent optical orthogonal frequency division multiplexing(CO-OFDM)*** first present a timing estimation method by designing the pattern of the training symbol,whose timing metric has a sharp and clear peak,to ensure accurate timing offset(TO)estimation *** we provide both data-aided(DA)and blind(BL)approaches to estimate the carrier frequency offset(CFO).For the DA algorithm,we utilize the same training symbol structure as the timing estimation does,while for the BL algorithm,we utilize the zero-subcarrier power(ZSP)to achieve full-range CFO *** that our joint timing and frequency synchronization approaches require only one OFDM symbol,which ensure not only the data transmission efficiency,but also the TO and CFO estimation performance.A modified BL ZSP algorithm is proposed to further improve the CFO estimation performance by taking the power average over a series of OFDM *** effectiveness of the TO estimation algorithm,and both the DA and BL CFO estimation algorithms are verified and demonstrated in both simulations and experiments.

关键词： timing offset (TO) carrier frequency offset (CFO) coherent optical orthogonal frequency division multiplexing (CO-OFDM) zero-subcarrier power (ZSP)

Uniform Asymptotics for Finite-time Ruin Probability in a Dependent Risk Model with General Stochastic Investment Return Process

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Acta Mathematicae Applicatae Sinica 2021年第4期37卷 847-857页

作者： Yang YANG kam Chuen YUEN Jun-feng LIU School of Statistics and Data Science Nanjing Audit UniversityNanjing211815China Department of Statistics and Actuarial Science The University of Hong KongPokfulam RoadHong KongChina

In this paper,we consider a non-standard renewal risk model with dependent claim sizes,where an insurance company is allowed to invest his/her wealth in financial assets,leading to some stochastic investment log-returns described as a general adapted càdlàg *** the assumptions that the claim sizes are heavy-tailed and the stochastic log-return process on investments is bounded from below almost surely,we derive some asymptotic formulas for the finite-time ruin probability holding uniformly in any finite time horizon.

关键词： finite-time ruin probability stochastic log-return process on investments upper tail asymptotic independence dominated variation uniformity

Development of An ICR Mouse Bioassay for Toxicity Evaluation in Neurotoxic Poisoning Toxins-Contaminated Shellfish

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Biomedical and Environmental Sciences 2013年第5期26卷 346-364页

作者： WONG Chun Kwan HUNG Patricia kam Kai Man Biotoxin Laboratory Microbiology DivisionPublic Health Laboratory Services BranchCentre for Health ProtectionDepartment of HealthShek Kip MeiKowloon

Objective To develop an ICR （female） mouse bioassay （MBA） for toxicity confirmation and evaluation of neurotoxins （brevetoxins）-contaminated shellfish. Methods Brevetoxins （BTX-B） as a causative agent of neurotoxic shellfish poisoning （NSP） under different shellfish matrices were intraperitoneally injected at different doses into mice to study their toxic effects and to differentiate the range of lethal and sublethal dosages. Their sensitivity and specificity were analyzed with 2 competitive ELISA kits for quantitative determination of standard BTX-B and dihydroBTX-B under different shellfish matrix-diluent combinations. Detection rates of MBA and two antibody-based assays for BTX-B from field NSP-positive shellfish samples were compared. Results BTX-B could be detected in shellfish tissues at concentration of 50-400 μg/100 g under shellfish matrix-Tween-saline media, which were appropriate to identify toxic shellfish at or above the regulatory limit （80 μg/100 g shellfish tissues）. The LD 50 identified was 455 g/kg for BTX-B under general shellfish matrices （excluding oyster matrices） dissolved in Tween-saline. The presence of shellfish matrices, of oyster matrices in particular, retarded the occurrence of death and toxicity presentation in mice. Two antibody-based assays, even in the presence of different shellfish matrix-diluent combinations, showed acceptable results in quantifying BTX-B and dihydroBTX-B well below the regulatory limit. Conclusion The two ELISA analyses agree favorably （correlation coefficient, r 0.96; Student＇s t-tests, P〉0.05） with the developed bioassay.

关键词： Antibody-based assay Brevetoxin ICR female mice LD 50 Mouse bioassay Neurotoxic shellfish poisoning

Aurone derivatives as Vps34 inhibitors that modulate autophagy

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Acta Pharmaceutica Sinica B 2019年第3期9卷 537-544页

作者： Guodong Li Joshua William Boyle Chung-Nga ko Wu Zeng Vincent kam Wai Wong Jian-Bo Wan Philip Wai Hong Chan Dik-Lung Ma Chung-Hang Leung State Key Laboratory of Quality Research in Chinese Medicine Institute of Chinese Medical SciencesUniversity of MacaoMacao999078China School of Chemistry Monash UniversityClayton3800Australia Department of Chemistry Hong Kong Baptist UniversityHong Kong999077China State Key Laboratory of Quality Research in Chinese Medicine Macao University of Science and TechnologyMacao999078China Department of Chemistry University of WarwickCoventry CV47ALUK

We report in this study the identification of a natural product-like antagonist(1a) of Vps34 as a potent autophagy modulator via structure-based virtual screening. Aurone derivative 1a strongly inhibited Vps34 activity in cell-free and cell-based assays. Significantly, 1a prevents autophagy in human cells induced either by starvation or by an mT OR inhibitor. In silico modeling and kinetic data revealed that 1a could function as an ATP-competitive inhibitor of Vps34. Moreover, it suppressed autophagy in vivo and without inducing heart or liver damage in mice. 1a could be utilized as a new motif for more selective and efficacious antagonists of Vps34 for the potential treatment of autophagy-related human diseases.

关键词： Autophagy Natural products Vps34 Inhibitor Structure-based virtual screening Vesicle trafficking Heart or liver damage Aurone derivative

Luminescent cyclometalated iridium(Ⅲ) dipyridoquinoxaline indole complexes as biological probes

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Science China Chemistry 2010年第10期53卷 2091-2098页

作者： LO Kenneth kam-Wing LEUNG Arthur Ho-Hon Department of Biology and Chemistry City University of Hong Kong

Four luminescent cyclometalated iridium(Ⅲ) dipyridoquinoxaline complexes appended with an indole moiety [Ir(N^C)2(N^N)] (PF6) (HN^C = 2-phenylpyridine, Hppy; N^N = 2-(N-(2-(indole-3-acetamido)ethyl)aminocarbonyl)dipyrido[3,2-f:2′,3′-h]quinox- aline, dpqC2indole (1a), N^N = 2-(N-(6-(indole-3-acetamido)hexyl)aminocarbonyl)dipyrido[3,2-f:2′,3′-h]quinoxaline, dpqC6indole (1b); HN^C = 7,8-benzoquinoline, Hbzq, N^N = dpqC2indole (2a), N^N = dpqC6indole (2b)) have been synthesized and characterized. Upon irradiation, all the complexes displayed moderately intense and long-lived luminescence under ambient condi-tions and in 77 K glass. On the basis of the photophysical data, the emission of the complexes has been assigned to an excited state of triplet metal-to-ligand charge-transfer (3MLCT) ((dπ(Ir)→π*(N^N)) character. Cyclic voltammetric studies revealed indole-based and iridium-based oxidations at ca. +1.10 V and +1.24 V vs. SCE, respectively, and ligand-based reductions at ca. -1.07 to-2.29 V vs. SCE. The interactions of the complexes with an indole-binding protein, bovine serum albumin (BSA), have been examined by emission titrations.

关键词： binding indole iridium luminescence probes

Asymptotics of the goodness-of-fit test for a partial linear model with randomly censored data

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Science China Mathematics 2003年第2期46卷 145-158页

作者：陈敏 kam C.YUEN 朱力行 Academy of Mathematics and System Sciences Chinese Academy of Sciences Department of Statistics and Actuarial Science the University of Hong Kong Department of Statistics and Actuarial Science the University of Hong Kong Hong Kong China

In this paper, we discuss the problem of testing the hypothesis that the underlying regression isa partial linear model. A test statistic, which is based on the quadratic form of a cusum process of residuals,is proposed. The asymptotic distributions of the test statistic under null hypothesis and the local alternativehypothesis are given. The number simulation shows that the test is available.

关键词： partial linear regression random censoring empirical process model checking

TRANSFECTION AND CELL FUSION BY FEMTOSECOND LASERS

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Journal of Innovative Optical Health Sciences 2011年第2期4卷 113-125页

作者： HAO HE SIU KAI koNG kam TAI CHAN Department of Electronic Engineering The Chinese University of Hong kong ShatinN.T.Hong Kong Department of Biochemistry The Chinese University of Hong kong ShatinN.T.Hong Kong

Biophotonics is an exciting and fast-expanding frontier which involves the fusion of advanced photonics and *** has not only created many novel methodologies for biomedical research,but also achieved many significant results as an *** to femtosecond(fs)laser technologies,important progresses have been made regarding the manipulation,imaging,and engineering of biological samples ranging from single molecules to tissues in the last 20 *** ultrashort pulses at near-infrared band provide many advantages:high nonlinear efficiency,low absorption by biological samples,high spatial and temporal resolution and confinement,and low *** are noninvasive and easy to *** the mechanism of how fs laser pulses interact with cells remains unclear,experimental results have shown that they could open up the cell membrane and hence made optical transfection and optical cell fusion *** this review,some of the seminal works on transfection and cell fusion by fs lasers are *** ideas behind and the experimental details will be described together with a highlight on their ***,the thermal effect is analyzed based on multiphoton excitation and plasma formation in an aqueous environment to explain the nontoxic characteristic of fs laser ***,some applications of fs laser induced transfection and cellcell fusion with potential major impact in biomedical sciences are proposed.

关键词： Biophotonics transfection cell fusion femtosecond laser

Alternative Approach to the Optimality of the Threshold Strategy for Spectrally Negative Lvy Processes

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Acta Mathematicae Applicatae Sinica 2013年第4期29卷 705-716页

作者： Ying SHEN Chuan-cun YIN kam Chuen YUEN School of Mathematical Sciences Qufu Normal UniversityChina Department of Statistics and Actuarial Science The University of Hong Kong

Consider the optimal dividend problem for an insurance company whose uncontrolled surplus precess evolves as a spectrally negative Levy process. We assume that dividends are paid to the shareholders according to admissible strategies whose dividend rate is bounded by a constant. The objective is to find a dividend policy so as to maximize the expected discounted value of dividends which are paid to the shareholders until the company is ruined. In this paper, we show that a threshold strategy （also called refraction strategy） forms an optimal strategy under the condition that the Levy measure has a completely monotone density.

关键词： Spectrally negative Levy process optimal dividend problem scale function complete monotonic-ity threshold strategy