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MODIFIED NEWTON＇S ALGORITHM FOR COMPUTIng THE GROUP INVERSES OF SIngULAR TOEPLITZ MATRICES

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Journal of Computational Mathematics 2006年第5期24卷 647-656页

作者： jian-feng Cai Michael K. ng Yi-min Wei Department of Mathematics The Chinese University of Hong Kong Hong Kong Department of Mathematics Hong Kong Baptist University Hong Kong School of Mathematical Sciences Fudan University Shanghai 200433 China ~ Key Laboratory of Mathematics for Nonlinear Sciences (Fudan University) Ministry of Education

Newton＇s iteration is modified for the computation of the group inverses of singular Toeplitz matrices. At each iteration, the iteration matrix is approximated by a matrix with a low displacement rank. Because of the displacement structure of the iteration matrix, the matrix-vector multiplication involved in Newton＇s iteration can be done efficiently. We show that the convergence of the modified Newton iteration is still very fast. Numerical results are presented to demonstrate the fast convergence of the proposed method.

关键词： Newton's iteration Group inverse Toeplitz matrix Displacement rank.

EFFICIENT BOX-CONSTRAINED TV-TYPE-l^1 ALGORITHMS FOR RESTORIng IMAGES WITH IMPULSE NOISE

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Journal of Computational Mathematics 2013年第3期31卷 249-270页

作者： Liyan Ma Michael K. ng jian Yu Tieyong Zeng School of Computer and Information Technology Beijing Jiaotong University Beijing 100044 China Department of Mathematics Hong Kong Baptist University Hong Kong China

In this paper, we study the restoration of images simultaneously corrupted by blur and impulse noise via variational approach with a box constraint on the pixel values of an image. In the literature, the TV-l^1 variational model which contains a total variation （TV） regularization term and an l^1 data-fidelity term, has been proposed and developed. Several numerical methods have been studied and experimental results have shown that these methods lead to very promising results. However, these numerical methods are designed based on approximation or penalty approaches, and do not consider the box constraint. The addition of the box constraint makes the problem more difficult to handle. The main contribution of this paper is to develop numerical algorithms based on the derivation of exact total variation and the use of proximal operators. Both one-phase and two-phase methods are considered, and both TV and nonlocal TV versions are designed. The box constraint [0, 1] on the pixel values of an image can be efficiently handled by the proposed algorithms. The numerical experiments demonstrate that the proposed methods are efficient in computational time and effective in restoring images with impulse noise.

关键词： Image restoration Impulse noise Total variation Nonlocal total variation Proximal Operators.

Spinal cord organoids add an extra dimension to traditional motor neuron cultures

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Neural Regeneration Research 2019年第9期14卷 1515-1516页

作者： Winanto Zi-jian Khong Jin-Hui Hor Shi-Yan ng Institute of Molecular and Cell Biology A*STAR Research EntitiesSingaporeSingapore Singapore Singapore(Winanto)School of Biological SciencesNanyang Technological UniversitySingaporeSingapore Department of Biological Sciences National University of SingaporeSingaporeSingapore Yong Loo Lin School of Medicine(Physiology) National University of SingaporeNational Neuroscience InstituteSingaporeSingaporeThe Third Affiliated Hospital of Guangzhou Medical UniversityGuangzhouGuangdong ProvinceChina

Since Lancaster et al.(2013)first described the formation of self-organizing cerebral organoids for modeling neurodevelopmental disorders,it became evident that three-dimensional(3D)neural organoid cultures are more superior systems for modeling neurodevelopment and neurodegeneration in *** use of a spinning bioreactor to grow organoids allows better nutrient absorption and enhances formation of neuroepithelial-like zones,making it a great tool to study neurodevelopment and *** organoids are 3D cell culture systems formed by proliferating,differentiating,migrating and self-organizing pools of neural *** mimic brain structures in their cell type composition,cytoarchitecture,and to some extent maturity and functionality(Lancaster et al.,2013).Because of these unique.

关键词： Since Lancaster neurodevelopment and neurodegeneration these unique

A Coordinate Gradient Descent Method for Nonsmooth Nonseparable Minimization

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Numerical Mathematics(Theory,Methods and Applications) 2009年第4期2卷 377-402页

作者： zh.ng-jian Bai Michael K. ng Liqun Qi School of Mathematical Sciences Xiamen University Xiamen 361005 China Centre for Mathematical Imaging and Vision and Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong Department of Applied Mathematics The Hong Kong Polytechnic University Hung Horn Hong Kong

This paper presents a coordinate gradient descent approach for minimizing the sum of a smooth function and a nonseparable convex *** find a search direction by solving a subproblem obtained by a second-order approximation of the smooth function and adding a separable convex *** a local Lipschitzian error bound assumption,we show that the algorithm possesses global and local linear convergence *** also give some numerical tests(including image recovery examples) to illustrate the efficiency of the proposed method.

关键词： Coordinate descent global convergence linear convergence rate

Lessons Learned from the Tragedy during the 100 km Ultramarathon Race in Baiyin,Gansu Province on 22 May 2021

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Advances in Atmospheric Sciences 2021年第11期38卷 1803-1810页

作者： Qinghong zh.ng Chan-Pang ng Kan DAI Jun XU jian TAng Juanzhen SUN Mu MU Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China HIWeather International Coordination Office Chinese Academy of Meteorological SciencesBeijing 100081China China Meteorological Administration Beijing 100081China National Center for Atmospheric Science BoulderCO 80307United States Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Sciences Fudan UniversityShanghai 200438China

Twenty-one runners died of hypothermia during the 100 km Ultramarathon Mountain race in Baiyin,Gansu Province on 22 May *** hypothermia was caused by a combination of low temperatures,precipitation,and high winds associated with a typical large-scale cold front passing by the race site that *** on historical hourly records of 13 meteorological surface stations over the past six years,temperature(3.0°C)and apparent temperature(−5.1°C)at 1200 LST as well as gust wind speed(11.2 m s^(−1))at 1100 LST on the day of the tragedy were found to be within the top or bottom 5th percentile for the month of *** precipitation was only moderate at this time,but when temperature lower than 3.0°C,gust wind speed greater than 11.2 m s^(−1),and precipitation greater than 0.1 mm for any adjacent three hours were combined together,1200 LST 22 May fell within the top 0.1%of *** European Centre for Medium-range Weather Forecasting model produced reasonably good forecasts of the low temperature and high wind one day and seven days before the event,*** on this study,lessons that can be learned from this tragedy are summarized from an academic perspective:Hazard and impact forecasts of high-impact weather events should be developed to increase the value of weather *** forecasts should be issued by government weather agencies and communicated well to the *** more importantly,knowledge of how to evaluate the impact of weather should be delivered to the public in the *** would like to extend our deepest condolences to the families and loved ones of the people who lost their lives in this tragedy,including 21 runners and one *** our efforts honor those who lost their lives by highlighting the value of weather forecasting and calling for greater action in the future.

关键词： low temperature high wind precipitation value of weather forecast

Peritoneal macrophages attenuate retinal ganglion cell survival and neurite outgrowth

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Neural Regeneration Research 2021年第6期16卷 1121-1126页

作者： Jia-jian Liang Yu-Fen Liu Tsz Kin ng Ci-Yan Xu Mingzhi zh.ng Chi Pui Pang Ling-Ping Cen Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong ShantouGuangdong ProvinceChina Shantou University Medical College ShantouGuangdong ProvinceChina Department of Ophthalmology and Visual Sciences the Chinese University of Hong KongHong Kong Special Administrative RegionChina

Inflammation is a critical pathophysiological process that modulates neuronal survival in the central nervous system after disease or ***,the effects and mechanisms of macrophage activation on neuronal survival remain *** the present study,we co-cultured adult Fischer rat retinas with primary peritoneal macrophages or zymosan-treated peritoneal macrophages for 7 *** analysis revealed that peritoneal macrophages reduced retinal ganglion cell survival and neurite outgrowth in the retinal explant compared with the control *** addition of zymosan to peritoneal macrophages attenuated the survival and neurite outgrowth of retinal ganglion *** media from peritoneal macrophages also reduced retinal ganglion cell survival and neurite *** result suggests that secretions from peritoneal macrophages mediate the inhibitory effects of these *** addition,increased inflammationand oxidation-related gene expression may be related to the enhanced retinal ganglion cell degeneration caused by zymosan *** summary,this study revealed that primary rat peritoneal macrophages attenuated retinal ganglion cell survival and neurite outgrowth,and that macrophage activation further aggravated retinal ganglion cell *** study was approved by the Animal Ethics Committee of the Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong,Shantou,Guangdong Province,China,on March 11,2014(approval ***20140311(2)-P01).

关键词： in vitro inflammation macrophages model neurite outgrowth optic nerve retinal ganglion cells survival

A major pathway for carbon and nitrogen losses-Gas emissions during storage of solid pig manure in China

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Journal of Integrative Agriculture 2019年第1期18卷 190-200页

作者： SHAN Nan LI Hu LI jian-zh.ng Ee Ling ng MA Yan WAng Li-gang CHEN Qing College of Resources and Environmental Sciences China Agricultural University Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural Sciences Faculty of Veterinary and Agricultural Sciences University of Melbourne

This study investigated the carbon(C) and nitrogen(N) gas emissions(N_2O,NH_3,CO_2 and CH_4) from solid pig manure management in *** emissions were quantified from static piles over 60 days during summer in China's Yangtze River Basin,using Drager-Tube and static chamber-gas chromatography *** emissions of NH_3 and N_2 O were observed at the early stage of storage,but high emission of CH_4 occured later during ***,62% of the total C in the original pile was lost; CO_2 and CH_4 emissions accounted for 57 and 0.2% of C lost *** the same time,41% of the total N in the original pile was lost; NH_3 and N_2 O emissions accounted for 15 and 0.3% of N lost *** volatilization of NH_3 during storage in summer was 4.56 g NH_3 per kg dry *** total greenhouse gas(GHG) emissions during storage accounted for 67.93 g CO_2 equivalent per kg dry weight; N_2 O and CH_4 contributed to 46 and 55% of total GHG emissions *** China's major role in pig production,further attention should given to pig manure management to mitigate its contribution to atmospheric pollution.

关键词： storage static pile ammonia nitrogen and carbon emissions greenhouse gas emission pig manure management

Effects of Medicines and Supplements on Spontaneous Pregnancy and Semen Parameters in Male Infertility:A Systematic Review Update and Network Meta-Analysis

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Engineering 2022年第9期16卷 198-209页

作者： jian Li Qi Wu Ernest Hung Yu ng Ben Willem J.Mol Xiao Ke Wu Chi Chiu Wang Department of Obstetrics and Gynecology First Affiliated HospitalHeilongjiang University of Chinese MedicineHarbin 150040China Department of Obstetrics and Gynecology The Affiliated Hospital of Gui Zhou Medical UniversityGuiyang 550004China Department of Obstetrics and Gynaecology Prince of Wales HospitalThe Chinese University of Hong KongHong Kong 999077China Department of Obstetrics and Gynecology Obstetrics and Gynecology HospitalFudan UniversityShanghai 30009China Department of Obstetrics and Gynaecology Queen Mary HospitalThe University of Hong KongHong Kong 999077China Department of Obstetrics and Gynaecology Monash UniversityClaytonVIC 3168Australia Heilongjiang Provincial Hospital Harbin Institute of TechnologyHarbin 150036China Reproduction and Development Laboratory Li Ka Shing Institute of Health SciencesThe Chinese University of Hong KongHong Kong 999077China i School of Biomedical SciencesThe Chinese University of Hong KongHong Kong 999077China The Chinese University of Hong Kong–Sichuan University Joint Laboratory of Reproductive Medicine Hong Kong 999077China

In this study,we used a network meta-analysis(NMA)to compare the effectiveness of medicines and supplements for idiopathic male infertility and to identify the best ***,Excerpta Medica Database(EMBASE),Ovid,and China National Knowledge Infrastructure(CNKI),were searched for the period from January 1990 to June 2021 using the keywords"male infertility,""medical therapy,""supplement/nutrient therapy,"and related *** controlled trials(RCTs)investigating medicines(mainly follicle-stimulating hormone(FSH),androgen,and clomiphene/tamoxifen)or supplements(mainly zinc,selenium,vitamin C or E,carnitine,coenzyme Q10(CoQ10),or combined treatment)for idiopathic infertile men were selected for *** reporting items for systematic reviews and meta-analysis(PRISMA)was used for data extraction,and a risk-of-bias tool and grades of recommendation,assessment,development,and evaluation(GRADE)system adapted to the NMA were employed to assess the quality of the *** primary outcomes were live birth and spontaneous pregnancy rate(SPR).The secondary outcomes were sperm parameters(including concentration,progressive motility,and morphology)and side *** total,65 RCTs involving 7541 men with sperm abnormalities but normal hormone levels were included.A total of 36 studies reported SPR but only three reported live birth *** quality of the included studies was found to be moderate to *** with a placebo or being untreated,carnitine plus vitamins significantly improved SPR(relative risk(RR)=3.7,95%confidence interval(95%CI),1.6-8.5);fatty acids significantly increased sperm concentrations(mean difference(MD)=12.5×10^(6)mL-1,95%CI,3.1×10^(6)-22.0×10^(6));and selective estrogen receptor modulator(SERM)plus CoQ10 significantly improved sperm progressive motility(MD=11.0%,95%CI,0.1%-21.9%)and normal sperm morphology(MD=11.0%,95%CI,4.6%-17.4%).The most optimal intervention was carnitine plus vitamins and fatty acids for SPR a

关键词： Male infertility Medicine Supplement Spontaneous pregnancy rate Sperm parameters

Numerical simulations of cellular detonation diffraction in a stable gaseous mixture

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Propulsion and Power Research 2016年第3期5卷 177-183页

作者： jian Li jianguo Ning Charles B.Kiyanda Hoi Dick ng State Key Laboratory of Explosion Science&Technology Beijing Institute of TechnologyBeijing 100081China Department of Mechanical and Industrial Engineering Concordia UniversityMontréalQCH3G 1M8Canada

In this paper,the diffraction phenomenon of gaseous cellular detonations emerging from a confined tube into a sudden open space is simulated using the reactive Euler equations with a two-step Arrhenius chemistry *** two-dimensional and axisymmetric configurations are used for modeling cylindrical and spherical expansions,*** chemical parameters are chosen for a stable gaseous explosive mixture in which the cellular detonation structure is highly *** mesh refinement(AMR)is used to resolve the detonation wave structure and its evolution during the *** numerical results show that the critical channel width and critical diameter over the detonation cell size are about 1371 and 2571,*** numerical findings are comparable with the experimental observation and confirm again that the critical channel width and critical diameter differ essentially by a factor close to 2,equal to the geometrical scaling based on front curvature *** unstable mixtures where instabilities manifested in the detonation front structure play a significant role during the transmission,the present numerical results and the observed geometrical scaling provide again evidence that the failure of detonation diffraction in stable mixtures with a regular detonation cellular pattern is dominantly caused by the global curvature due to the wave divergence resulting in the global decoupling of the reaction zone with the expanding shock front.

关键词： Detonations Diffraction Pulse detonation engine Stable mixture Adaptive mesh refinement(AMR)