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Theoretical and experimental studies of heat transfer with moving phase-change interface in freezing and thawing of porous potting soil

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第1期10卷 1-6页

作者： Michael K.H.leung Kit-ying chan Department of Mechanical Engineering the University of Hong Kong

Soil in a cold region is subject to frequent freezing and thawing *** frozen for a prolonged period may cause adverse freeze damage to the plants due to cell dehydration or root cell *** is important to understand the detailed heat transfer behaviors of the freezing and thawing processes to prevent freeze damage,and to devise proper mitigation measures for effective pot planting in cold regions.A theoretical model was developed to analyze the transient moving phase-change interface heat transfer in the freezing and thawing of porous potting *** theoretical derivation is based on the assumption that the soil freezes completely at a single *** poromechanic effects on heat transfer behavior were *** spatial domain of the problem was simplified to a 1D spherical coordinate system with variation in the radial ***'s function was applied to solve for the time-dependent body *** were conducted for validation of the theoretical *** agreement between the theoretical predictions and experimental measurements was *** theoretical model developed can be easily used to determine the sensitivity of various parameters in the freezing/thawing processes,e.g.,thermal properties of soil,ambient temperature,and planting pot size.

关键词： Porous soil Freezing Thawing Moving phase-change interface Theoretical model

Urocortin and cardiovascular protection

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Acta Pharmacologica Sinica 2004年第3期25卷 3-11页

作者： Chi-wai LAU,Yau-chi chan,Suk-ying TSANG,Franky leung chan The Chinese University of Hong Kong Hong Kong China Department of Anatomy The Chinese University of Hong Kong Hong Kong China Department of Anatomy The Chinese University of Hong Kong Hong Kong China Department of Anatomy The Chinese University of Hong Kong Hong Kong China Department of Anatomy

Urocortin and other hypothalamus corticotropin-releasing factor (CRF) polypeptides play biologically diverse roles in the stress, cardiovascular and inflammatory responses by acting on central and peripheral CRF receptors. Urocortin shows a significantly high sequence homology to CRF, and the concurrent expression of type-2 CRF (CRF2) receptors with urocortin in the heart suggests that urocortin may play a physiological role in the cardiac function. Urocortin is thought to be the endogenous agonist producing the cardiovascular actions previously attributed to CRF. This review highlights the current novel findings on the molecular and cellular mechanisms by which urocortin may exert its cardiovascular protective action.

关键词： urocortin corticotropin-releasing hormone vascular smooth muscle heart vasodilaion second messenger system protein kinases

Structural changes of a Tropical Cyclone during Landfall: β-plane Simulations

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Advances in Atmospheric Sciences 2010年第5期27卷 1143-1150页

作者： K.C.SZETO johnny C.L.chan School of Energy and Environment City University of Hong Kong

This study investigated the effects of landfall on the structure of a tropical cyclone （TC）. Numerical simulations were performed using the Weather Research and Forecasting Model on a β-plane. Two landfall experiments, one with an east–west and another with a north–south oriented coastline, were performed. Similar to previous studies on an f-plane, large-scale flows in the low-to-middle troposphere were modified due to friction. A pair of counter rotating gyres was found, which was shown to be consistent with the slight deffection of the TC relative to the control experiment without land. Compared to previous f-plane simulations, because of the inherent asymmetries due to the β-gyres, the large-scale pattern of flows and convergences/divergences related to friction were found to depend on coastline orientations. On the other hand, regardless of the coastline orientation, convergences were found to be stronger to the left for both cases near landfall, as in previous f-plane simulations. Such a convergence pattern subsequently induced a change in convection and rainfall at the eyewall.

关键词： tropical cyclone landfall numerical simulations

Sensitivity of precipitation statistics to urban growth in a subtropical coastal megacity cluster

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Journal of Environmental Sciences 2017年第9期29卷 6-12页

作者： Christopher Claus Holst johnny C.L.chan Chi-Yung Tam School of Energy and Enuironment City Uniuersity of liong KongHong KongChina Guy Carpenter Asia-Pacific Climate Impact Centre City Uniuersity of Hong KongHong KongChina Earth System Science Programme The Chinese Uniuersity of Hong KongHong KongChina

This short paper presents an investigation on how human activities may or may not affect precipitation based on numerical simulations of precipitation in a benchmark case with modified lower boundary conditions, representing different stages of urban development in the model. The results indicate that certain degrees of urbanization affect the likelihood of heavy precipitation significantly, while less urbanized or smaller cities are much less prone to these effects. Such a result can be explained based on our previous work where the sensitivity of precipitation statistics to surface anthropogenic heat sources lies in the generation of buoyancy and turbulence in the planetary boundary layer and dissipation through triggering of convection. Thus only mega cities of sufficient size, and hence human-activity-related anthropogenic heat emission, can expect to experience such effects. In other words, as cities grow, their effects upon precipitation appear to grow as well.

关键词： Urban precipitation Micro climate sensitivity Urbanization

Predictive Ability of Hypertriglyceridemic Waist,Hypertriglyceridemic Waist-to-Height Ratio,and Waist-to-Hip Ratio for Cardiometabolic Risk Factors Clustering Screening among Chinese Children and Adolescents

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Biomedical and Environmental Sciences 2024年第3期37卷 233-241页

作者： XIAO Tian Li YUAN Shu Qian GAO Jing Yu Julien SBaker YANG Yi De WANG Xi Jie ZHENG chan Juan DONG Yan Hui ZOU Zhi Yong Key Laboratory of Molecular Epidemiology of Hunan Province School of MedicineHunan Normal UniversityChangsha 410081HunanChina The Institute of Interdisciplinary Studies Hunan Normal UniversityChangsha 410013HunanChina Chenzhou First People's Hospital Chenzhou 423000HunanChina Centre for Health and Exercise Science Research Hong Kong Baptist UniversityKowloon TongHong Kong 999077China Department of Sport Physical Education and HealthHong Kong Baptist UniversityKowloon TongHong Kong 999077China Vanke School of Public Health Tsinghua UniversityBeijing 100084China Institute of Child and Adolescent Health School of Public HealthPeking University Health Science CenterBeijing 100191China

Objective Hypertriglyceridemic waist(HW),hypertriglyceridemic waist-to-height ratio(HWHtR),and waist-to-hip ratio(WHR)have been shown to be indicators of cardiometabolic risk ***,it is not clear which indicator is more suitable for children and *** aimed to investigate the relationship between HW,HWHtR,WHR,and cardiovascular risk factors clustering to determine the best screening tools for cardiometabolic risk in children and *** This was a national cross-sectional *** and biochemical variables were assessed in approximately 70,000 participants aged 6–18 years from seven provinces in ***,physical activity,dietary intake,and family history of chronic diseases were obtained through ***,χ2 and logistic regression analysis was *** A significant sex difference was observed for HWHtR and WHR,but not for HW *** risk of cardiometabolic health risk factor clustering with HW phenotype or the HWHtR phenotype was significantly higher than that with the non-HW or non-HWHtR phenotypes among children and adolescents(HW:OR=12.22,95%CI:9.54-15.67;HWHtR:OR=9.70,95%CI:6.93-13.58).Compared with the HW and HWHtR phenotypes,the association between risk of cardiometabolic health risk factors(CHRF)clustering and high WHR was much weaker and not significant(WHR:OR=1.14,95%CI:0.97-1.34).Conclusion Compared with HWHtR and WHR,the HW phenotype is a more convenient indicator with higher applicability to screen children and adolescents for cardiovascular risk factors.

关键词： Hypertriglyceridemic waist Waist-to-hip ratio Children and adolescents China Hypertriglyceridemic waist-to-height ratio Cardiovascular risk factors

CONVERGENCE OF NEWTON＇S METHOD FOR A MINIMIZATION PROBLEM IN IMPULSE NOISE REMOVAL

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Journal of Computational Mathematics 2004年第2期22卷 168-177页

作者： RaymondH.chan chung-waHo MilaNikolova DepartmentofMathematics TheChineseUniversityofHongKongShatinHongKong CentredeMathématiquesetdeLeursApplications(CMLA-CNRSUMR8536) ENSdeCachan61av.duPresidentWilson94235CachanCedexFrance

Recently, two-phase schemes for removing salt-and-pepper and random-valued impulse noise are proposed in [6, 7]. The first phase uses decision-based median filters to locate those pixels which are likely to be corrupted by noise (noise candidates). In the second phase, these noise candidates are restored using a detail-preserving regularization method which allows edges and noise-free pixels to be preserved. As shown in [18], this phase is equivalent to solving a one-dimensional nonlinear equation for each noise *** can solve these equations by using Newton's method. However, because of the edgepreserving term, the domain of convergence of Newton's method will be very narrow. In this paper, we determine the initial guesses for these equations such that Newton's method will always converge.

关键词： Impulse noise denoising Newton's method Variational method

Effects of SARS-CoV-2 infection on incidence and treatment strategies of hepatocellular carcinoma in people with chronic liver disease

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World Journal of Hepatology 2024年第2期16卷 211-228页

作者： Lung-Yi Mak Matthew Shing Hin chung Xue Li Francisco Tsz Tsun Lai Eric Yuk Fai Wan Celine Sze Ling Chui Franco Wing Tak Cheng Esther Wai Yin chan Ching Lung Cheung Ivan Chi Ho Au Xi Xiong Wai-Kay Seto Man-Fung Yuen Carlos King Ho Wong Ian Chi Kei Wong Department of Medicine The University of Hong KongHong KongChina State Key Laboratory of Liver Research The University of Hong KongHong KongChina Department of Pharmacology and Pharmacy The University of Hong KongHong KongChina Laboratory of Data Discovery for Health(D24H) Hong Kong Science and Technology ParkHong KongChina Department of Family Medicine and Primary Care The University of Hong KongHong KongChina School of Nursing The University of Hong KongHong KongChina School of Public Health The University of Hong KongHong KongChina Research Department of Practice and Policy University College LondonLondon WC1E 6BTUnited Kingdom Aston School of Pharmacy Aston UniversityBirmingham B47ETUnited Kingdom

BACKGROUND Chronic liver disease(CLD)was associated with adverse clinical outcomes among people with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)*** To determine the effects of SARS-CoV-2 infection on the incidence and treatment strategy of hepatocellular carcinoma(HCC)among patients with *** A retrospective,territory-wide cohort of CLD patients was identified from an electronic health database in Hong *** with confirmed SARS-CoV-2 infection[coronavirus disease 2019(COVID-19)+CLD]between January 1,2020 and October 25,2022 were identified and matched 1:1 by propensity-score with those without(COVID-19-CLD).Each patient was followed up until death,outcome event,or November 15,*** outcome was incidence of *** outcomes included all-cause mortality,adverse hepatic outcomes,and different treatment strategies to HCC(curative,non-curative treatment,and palliative care).Analyses were further stratified by acute(within 20 d)and post-acute(21 d or beyond)phases of SARS-CoV-2 *** rate ratios(IRRs)were estimated by Poisson regression *** Of 193589 CLD patients(>95%non-cirrhotic)in the cohort,55163 patients with COVID-19+CLD and 55163 patients with COVID-19-CLD were included after 1:1 propensity-score *** 249-d median follow-up,COVID-19+CLD was not associated with increased risk of incident HCC(IRR:1.19,95%CI:0.99-1.42,P=0.06),but higher risks of receiving palliative care for HCC(IRR:1.60,95%CI:1.46-1.75,P<0.001),compared to *** both acute and post-acute phases of infection,COVID-19+CLD were associated with increased risks of allcause mortality(acute:IRR:7.06,95%CI:5.78-8.63,P<0.001;post-acute:IRR:1.24,95%CI:1.14-1.36,P<0.001)and adverse hepatic outcomes(acute:IRR:1.98,95%CI:1.79-2.18,P<0.001;post-acute:IRR:1.24,95%CI:1.13-1.35,P<0.001),compared to *** Although CLD patients with SARS-CoV-2 infection were not associated with increased risk of HCC,they

关键词： SARS-CoV-2 infection Chronic liver disease Long COVID Post-COVID-19 syndrome Cirrhosis Hepatocellular carcinoma

Retrohepatic vena cava deroofing in living donor liver transplantation for caudate hepatocellular carcinoma

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Hepatobiliary & Pancreatic Diseases International 2013年第5期12卷 552-555页

作者： See Ching chan William W Sharr Tan To Cheung Albert CY chan Simon HY Tsang Kenneth SH Chok Kin chung leung chung Mau Lo Department of Surgery The University of Hong Kong State Key Laboratory for Liver Research The University of Hong Kong Department of Pathology The University of Hong Kong

The removal of tumor together with the native liver in living donor liver transplantation for hepatocellular carcinoma is challenged by a very close resection margin if the tumor abuts the inferior vena *** is in contrast to typical deceased donor liver transplantation where the entire retrohepatic inferior vena cava is included in total *** we report a case of deroofing the retrohepatic vena cava in living donor liver transplantation for caudate hepatocellular *** order to ensure clear resection margins,the anterior portion of the inferior vena cava was *** right liver graft was inset into a Dacron vascular graft on the back table and the composite graft was then implanted to the recipient inferior vena *** this technique,we observed the no-touch technique in tumor removal,hence minimizing the chance of positive resection margin as well as the chance of shedding of tumor cells during manipulation in operation.

关键词： hepatocellular carcinoma liver transplantation

Numerical characteristics of the full operator hybrid simulation method

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Earthquake Engineering and Engineering Vibration 2011年第3期10卷 453-463页

作者： chung-chan Hung Yong-Song Chen Department of Civil Engineering Central University （NCU） Chinese Taipei Department of Mechanical Engineering Chung Cheng University （NCCU） Chinese Taipei

The full operator method （FOM） has been proposed to overcome some of the shortcomings of the commonly used operator splitting method （OSM）. In particular, the FOM is improved by increasing the accuracy of both the predictor and corrector using the estimated tangent stiffness of the tested structure. The numerical characteristics of the FOM, including stability and accuracy, are investigated in this study. It is shown that FOM is conditionally stable. The stability and accuracy characteristics are dependent on the accuracy of the estimated tangent stiffness and the parameters associated with the acceleration variation in the time-stepping integration method. Mass-spring systems with different types of nonlinearity, including hardening, stiffening, and softening behavior, are used to evaluate the performance of the FOM. It is found that the FOM can capture these types of nonlinearity with satisfactory accuracy. Using a prototype 12-story composite coupled wall system, the influences of the strong nonlinearity of the system as well as the displacement control errors from hydraulic actuators on the performance of the FOM are explored. The results show that the FOM is capable of generating reasonably accurate results despite the presence of strong structural nonlinearity and displacement control errors.

关键词： hybrid simulation tangent stiffness numerical characteristic composite coupled wall system collapse behavior nonlinear behavior