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NUMERICAL StUDIES OF A CLASS OF COMPOSItE PRECONDItIONERS

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Journal of Computational Mathematics 2014年第2期32卷 136-151页

作者： Qiang Niu Michael ng Mathematics and Physics Centre Xi'an Jiaotong-Liverpool University Suzhou 215123 China Department of Mathematics Hong Kong Baptist University Kowloon Tong Hong Kong

In this paper, we study a composite preconditioner that combines the modified t.ngential frequency filtering decomposition with the ILU（O） factorization. Spectral property of the composite preconditioner is examined by the approach of Fourier analysis. We illustrate that condition number of the preconditioned matrix by the composite preconditioner is asymptotically bounded by O（hp -2/3） on a standard model problem. Performance of the composite preconditioner is compared with other preconditioners on several problems arising from the discretization of PDEs with discontinuous coefficients. Numerical results show that performance of the proposed composite preconditioner is superior to other relative preconditioners.

关键词： Preconditioner ILU t.ngential frequency filtering decomposition GMRES.

Lowered testosterone in male obesity： mechanisms, morbidity and management

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Asian Journal of Andrology 2014年第2期16卷 223-231,I0008页

作者： Mark ng t.ng Fui Department of Medicine Austin Health University of Melbourne Melbourne Department of Endocrinology Austin Health Melbourne Victoria Australia

With increasing modernization and urbanization of Asia, much of the future focus of the obesity epidemic will be in the Asian region. Low testosterone levels are frequently encountered in obese men who do not otherwise have a recognizable hypothalamic-pituitary-testicular （HPt） axis pathology. Moderate obesity predominantly decreases total testosterone due to insulin resistance-associated reductions in sex hormone binding globulin. More severe obesity is additionally associated with reductions in free testosterone levels due to suppression of the HPt axis. Low testosterone by itself leads to increasing adiposity, creat.ng a self-perpetuat.ng cycle of metabolic complications. Obesity-associated hypotestosteronemia is a functional, non-permanent state, which can be reversible, but this requires substantial weight loss. While testosterone treatment can lead to moderate reductions in fat mass, obesity by itself, in the absence of symptomatic androgen deficiency, is not an established indication for testosterone therapy. testosterone therapy may lead to a worsening of untreated sleep apnea and compromise fertility. Whether testosterone therapy augments diet- and exercise-induced weight loss requires evaluation in adequately designed randomized controlled clinical trials.

关键词： androgens hypogonadism obesity testosterone weight loss

the impact of alpha-fetoprotein (AFP), child-turcotte-pugh (CtP) score and disease staging on the survival of hepatocellular carcinoma (HCC) patients: a retrospective cohort from single oncology center

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Oncology research 2025年第1期33卷 149-160页

作者： Nasser Mulla Yousef Katib Asim M Almughamsi Duaa S Alkhayat Mohamed Mosaad Samir t Alfotih Rawan Alaofi Department of Internal Medicine Faculty of Medicine Taibah University Madinah 42278 Saudi Arabia. Department of Radiology Faculty of Medicine Taibah University Madinah 42278 Saudi Arabia. Department of Surgery Faculty of Medicine Taibah University Madinah 42278 Saudi Arabia. Department of Endemic and Infectious Diseases Suez Canal University Ismailia 41522 Egypt. King Salman bin Abdulaziz Medical City Madinah 42311 Saudi Arabia. Prince Mohammed Bin Abdulaziz Hospital Madinah 41511 Saudi Arabia.

Background:Hepatocellular carcinoma (HCC) is the most common cause of cancer-related death in Saudi Arabia. Our study aimed to investigate the patterns of HCC and the effect of tNM staging, Alfa-fetoprotein (AFP), and Child-turcotte Pugh (CtP) on patients' overall survival (OS).Methods:A retrospective analysis was conducted on 43 HCC patients at a single oncology center in Saudi Arabia from 2015 to 2020. All patients had to fulfill one of the following criteria: (a) a liver lesion reported as definitive HCC on dynamic imaging and/or (b) a biopsy-confirmed diagnosis.Results:the mean patient age of all HCC cases was 66.8 with a male-to-female ratio of 3.3:1. All patients were stratified into two groups: viral HCC (n = 22, 51%) and non-viral HCC (n = 21, 49%). Among viral-HCC patients, 55% were due to HBV and 45% due to HCV. Cirrhosis was diagnosed in 79% of cases. Age and sex did not significantly statistically differ in OS among viral and non-viral HCC patients (-value > 0.05). About 65% of patients had tumor size >5 cm during the diagnosis, with a significant statistical difference in OS (-value = 0.027). AFP was >400 ng/ml in 45% of the patients. there was a statistically significant difference in the OS in terms of AFP levels (-value = 0.021). A statistically significant difference was also observed between the CtP score and OS (-value = 0.02). CtP class B had the longest survival. BSC was the most common treatment provided to HCC patients followed by sorafenib therapy. there was a significant statistical difference in OS among viral and non-viral HCC patients (-value = 0.008).Conclusions:the most common predictors for OS were the underlying cause of HCC, AFP, and tumor size. Being having non-viral etiology, a tumor size >5 cm, an AFP > 400 ng/mL, and a CtP score class C were all negatively associated with OS.

关键词： Alpha-fetoprotein (AFP) Child-turcotte-pugh Hepatocellular carcinoma Pattern Progression free survival

On compact splitt.ng complex submanifolds of quotients of bounded symmetric domains

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Science China Mathematics 2017年第6期60卷 1057-1076页

作者： MOK ngaiming ng SuiChung Department of Mathematics The University of Hong Kong Department of Mathematics Shanghai Key Laboratory of PMMPEast China Normal University

We study compact complex submanifolds S of quotient manifolds X =Ω/F of irreducible bounded symmetric domains by torsion free discrete lattices of automorphisms, and we are interested in the characterization of the totally geodesic submanifolds among compact splitt.ng complex submanifolds S C X, i.e., under the assumption that the t.ngent sequence over S splits holomorphically. We prove results of two types. the first type of results concerns S C X which are characteristic complex submanifolds, i.e., embedding Ω as an open subset of its compact dual manifold M by means of the Borel embedding, the non-zero （1, 0）-vectors t.ngent to S lift under a local inverse of the universal covering map π → X to minimal rational t.ngents of M. We prove that a compact characteristic complex submanifold S C X is necessarily totally geodesic whenever S is a splitt.ng complex submanifold. Our proof generalizes the case of the characterization of totally geodesic complex submanifolds of quotients of the complex unit ball B^n obtained by Mok （2005）. the proof given here is however new and it is based on a monotonic property of curvatures of Hermitian holomorphic vector subbundles of Hermitian holomorphic vector bundles and on exploit.ng the splitt.ng of the t.ngent sequence to identify the holomorphic t.ngent bundle ts as a quotient bundle rather than as a subbundle of the restriction of the holomorphic t.ngent bundle tx to S. the second type of results concerns characterization of total geodesic submanifolds among compact splitt.ng complex submanifolds S C X deduced from the results of Aubin （1978） and Yau （1978） which imply the existence of Kahler-Einstein metrics on S C X. We prove that compact s- plitt.ng complex submanifolds S C X of sufticiently large dimension （depending on ） are necessarily totally geodesic. the proof relies on the Hermitian-Einstein property of holomorphic vector bundles associated to tS, which implies that endomorphisms of such bundles are parallel, and the co

关键词： bounded symmetric domains t.ngent sequence splitt.ng complex submanifolds varieties of minimal rational t.ngents K/ihler-Einstein metrics

the benefits of being dominant:health correlates of male social rank and age in a marmot

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Current Zoology 2022年第1期68卷 19-26页

作者： Kenta UCHIDA Rachel ng Samuel A.VYDRO Jennifer E.SMItH Daniel t.BLUMStEIN Department of Ecology&Evolutionary Biology University of CaliforniaLos AngelesCA 90095-1606USA Department of Biology Mills CollegeOaklandCA 94613USA the Rocky Mountain Biological Laboratory Crested ButteCO 81224USA

the benefits of dominance may not come without costs,particularly for *** example,the“immunocompetence handicap hypothesis”states that males with enhanced mat.ng success allocate resources to enhance reproductive output at a cost to their current health,whereas the“resource quality hypothesis”predicts that high-ranking males may benefit from increased reproduction and good *** the predictions from each have been well tested in captive animals and in a variety of highly social primates,fewer studies have been carried out in free-living,facultatively social *** adult male yellow-bellied marmots(Marmota flaviventer),we evaluated predictions of these hypotheses by examining the relationship between social rank and 2 health indicators—fecal glucocorticoid metabolite(FCM)levels,and neutrophil/lymphocyte(N/L)ratios—after account.ng for variation explained by age,body mass,and *** found that higher-ranking males tended to have a lower N/L ratio(reflect.ng good health)than lower-ranking individuals,whereas FCM levels were not significantly related to *** addition,heavier male marmots had lower N/L ratios,whereas body mass was not associated with FCM *** also found that older adult males had lower FCM levels(reflect.ng less physiological stress)but higher N/L ratios than younger ***,we found that FCM levels decreased as the active season progressed and FCM levels were associated with the time of the ***,our results suggest that socially-dominant male marmots enjoyed better,not worse health in terms of lower N/L ratios.

关键词： immunocompetence handicap hypothesis life history trade-offs N/L ratio physiological stress resource quality hypothesis

Dysfunction of synaptic endocytic trafficking in Parkinson's disease

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Neural Regeneration Research 2024年第12期19卷 2649-2660页

作者： Xin Yi ng Mian Cao Programme in Neuroscience and Behavioural Disorders Duke-NUS Medical SchoolSingaporeSingapore Department of Physiology National University of SingaporeSingaporeSingapore

Parkinson's disease is characterized by the selective degeneration of dopamine neurons in the nigrostriatal pathway and dopamine deficiency in the *** precise reasons behind the specific degeneration of these dopamine neurons remain largely *** investigations have identified over 20 causative PARK genes and 90 genomic risk loci associated with both familial and sporadic Parkinson's ***,several of these genes are linked to the synaptic vesicle recycling process,particularly the clathrinmediated endocytosis *** suggests that impaired synaptic vesicle recycling might represent an early feature of Parkinson's disease,followed by axonal degeneration and the eventual loss of dopamine cell bodies in the midbrain via a"dying back"***,several new animal and cellular models with Parkinson's disease-linked mutations affect.ng the endocytic pathway have been created and extensively *** models faithfully recapitulate certain Parkinson's disease-like features at the animal,circuit,and cellular levels,and exhibit defects in synaptic membrane trafficking,further support.ng the findings from human genetics and clinical *** this review,we will first summarize the cellular and molecular findings from the models of two Parkinson's disease-linked clathrin uncoat.ng proteins:auxilin(DNAJC6/PARK19)and synaptojanin 1(SYNJ1/PARK20).the mouse models carrying these two PARK gene mutations phenocopy each other with specific dopamine terminal pathology and display a potent synergistic ***,we will delve into the involvement of several clathrin-mediated endocytosis-related proteins(GAK,endophilin A1,SAC2/INPP5 F,synaptotagmin-11),identified as Parkinson's disease risk factors through genome-wide association studies,in Parkinson's disease *** will also explore the direct or indirect roles of some common Parkinson's disease-linked proteins(alpha-synuclein(PARK1/4),Parkin(PARK2),and LRRK2(PARK

关键词： autophagy auxilin/PARK19 clathrin-mediated endocytosis dopamine neurons neurodegeneration nigrostriatal pathway Parkinson's disease synaptic vesicle recycling synaptojanin1/PARK20

AN APPROACH tO ANALYSIS OF SIngLE PIER BASED ON tHE VARIAtIONAL PRINCIPLE IN MULtI-LAYERED SOIL

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Acta Mechanica Solida Sinica 2001年第3期14卷 275-282页

作者： ng Shiu Cho Department of Civil Enginddring The Hong Kong University of Science and TechnologyClearwaler BayHong Kong

In this study, a variational approach to the settlement analysisof an axially loaded pier em- bedded in a multi-layered soil profileis presented. In this method, the soil profile and the embedded pierare divided into a number of sub-layers according to the actualnumber o soil layers observed in the field. the displacement shapefunction of each soil layer is given as a product of an exponentialequation along the pier depth and the Bessel's solution in the radialdirection.

关键词： pier pile settlement

Improved GaN grown on Si(111) substrate using ammonia flow modulation on SiN_x mask layer by MOCVD

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Science China(technological Sciences) 2009年第9期52卷 2758-2761页

作者： ng KaiWei LAU KeiMay Department of Electrical and Electronic Engineering Hong Kong University of Science & Technology Clear Water BayKowloon Hong Kong China

In this paper,1 μm n-GaN was grown by using varied and fixed ammonia flow (NH3) on SiNx mask layer on Si(111) substrate using metal organic chemical vapor deposition (MOCVD). In-situ optical reflectivity traces of GaN growth show that the three-to two-dimensional process has been prolonged by using varied ammonia flow on SiNx mask layer method compared with that grown by fixing ammonia flow. Structural and optical properties were characterized by high-resolution X-ray diffraction and photolu-minescence,and compared with the sample grown by fixing ammonia flow,GaN grown using the varied ammonia flow on SiNx mask layer showed better structure and optical quality. It was assumed that the low NH3 flow in the initial growth stage considerably increased the GaN island density on the nano-porous SiNx layer by enhancing vertical growth. Lateral growth was significantly favored by high NH3 flow in the subsequent step. As a result,the improved crystal and optical quality was achieved utilizing NH3 flow modulation for GaN buffer growth on Si(111) substrate.

关键词： GaN epilayer MOCVD NH3 modulation

ON INtEGRItY ASSESSMENt OF AXISYMMEtRIC COMPONENtS OPERAt.ng WItHIN CREEP REGIME

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Chinese Journal of Mechanical Engineering 2006年第4期19卷 492-495页

作者： ZARRABI K LAWRENCE ng School of Mechanical and Manufacturing Engineering University of New South Wales Sydney NSW 2052 Australia

A multiaxial paradigm for predict.ng creep damage/lives of components is described. Although in principle the paradigm is general, it is verified using axisymmetric experimental data. It is shown that the proposed paradigm is capable of predict.ng creep lives with an error of less than 2%. It is also shown that the proposed paradigm is more accurate than the reference stress method.

关键词： Creep damage Creep life