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Programmed cell death in developing human fetal CNS

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Chinese Science Bulletin 2000年第22期45卷 2082-2084页

作者： chan W.y. Department of Anatomy Faculty of MedicineThe Chinese University of Hong KongShatinN.T.Hong KongChina

The spatial and temporal distributions of programmed cell death (PCD) in developing central nervous system (CNS) of human fetuses ranging from 12 to 39 weeks of gestation were investigated using techniques of flow cytometry and terminal transferase-mediated nick end labeling (TUNEL). The results showed that PCD did occur in every representative brain region of all fetuses examined in different stages. It was found that there were two peaks of PCD appearing at the 12th and 39th weeks respectively, which suggested that the first peak of apoptosis may be involved in the selective elimination of neurons overproduced during the early development and the second may play an important role in establishing the correct neuronal circuitry.

关键词： programmed cell death (PCD) fetus central nervous system development.

Performance of LIDAR- and radar-based turbulence intensity measurement in comparison with anemometer-based turbulence intensity estimation based on aircraft data for a typical case of terrain-induced turbulence in association with a typhoon

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第7期14卷 469-481页

作者： P.W.chan y.F.LEE Hong Kong Observatory

The Hong Kong Observatory (HKO) provides low-level turbulence alerting service for the Hong Kong International Airport (HKIA) through the windshear and turbulence warning system (WTWS). In the WTWS, turbulence intensities along the flight paths of the airport are estimated based upon correlation equations established between the surface anemometer data and the turbulence data from research aircraft before the opening of the airport. The research aircraft data are not available on day-to-day basis. The remote sensing meteorological instruments, such as the Doppler light detection and ranging (LIDAR) and radar, may be used to provide direct measurements of turbulence intensities over the runway corridors. The performances of LIDAR- and radar-based turbulence intensity data are studied in this paper based on actual turbulence intensity measurements made on 423 commercial jets for a typical case of terrain-induced turbulence in association with a typhoon. It turns out that, with the tuning of the relative operating characteristic (ROC) curve between hit rate and false alarm rate, the LIDAR-based turbulence intensity measurement performs better than the anemometer-based estimation of WTWS for turbulence intensity at moderate level or above. On the other hand, the radar-based measurement does not perform as well when compared with WTWS. By combining LIDAR- and radar-based measurements, the performance is slightly better than WTWS, mainly as a result of contribution from LIDAR-based measurement. As a result, the LIDAR-based turbulence intensity measurement could be used to replace anemometer-based estimate for non-rainy weather conditions. Further enhancements of radar-based turbulence intensity measurement in rain would be necessary.

关键词： Fault tolerant High availability quadruple vital computer (HAQVC) Reliability availability maintainability and safety (RAMS)

Purge and trap method to determine alpha factors of VOC liquid-phase mass transfer coefficients

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Chinese Science Bulletin 2000年第S1期45卷 76-79页

作者： S.C.Lee L.y.chan C.y.chan Department of Civil & Structural Engineering The Hong Kong Polytechnic UniversityHong KongChina Correspondence should be addressed to Wang XinmingDepartment of Civil & Structural EngineeringThe Hong Kong Polytechnic UniversityHong KongChina Correspondence should be addressed to Wang XinmingDepartment of Civil & Structural EngineeringThe Hong Kong Polytechnic UniversityHong KongChina Correspondence should be addressed to Wang Xinming

A theoretical approach and laboratory practice of determining the alpha factors of volatile organic compound (VOC) liquid-phase mass transfer coefficients are present in this study. Using Purge & Trap Concentrator, VOC spiked water samples are purged by high-purity nitrogen in the laboratory, the VOC liquid-phase mass transfer rate constants under the laboratory conditions are then obtained by observing the variation of VOCs purged out of the water with the purge time. The alpha factors of VOC liquid-phase mass transfer coefficients are calculated as the ratios of the liquid-phase mass transfer rate constants in real water samples to their counterparts in pure water under the same experimental conditions. This direct and fast approach is easy to control in the laboratory, and would benefit mutual comparison among researchers, so might be useful for the study of VOC mass transfer across the liquid-gas interface.

关键词： mass transfer coefficient purge and trap volatile organic compounds alpha factor.

Perception of Potential Health Risk of Climate change and Utilization of Fans and Air Conditioners in a Representative Population of Hong Kong

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International Journal of Disaster Risk Science 2020年第1期11卷 105-118页

作者： yang Gao Emily y.y.chan Holly C.y.Lam Aiwei Wang Department of Sport and Physical Education Hong Kong Baptist UniversityHong KongChina Collaborating Centre for Oxford University and CUHK for Disaster and Medical Humanitarian Response The Jockey Club School of Public Health and Primary CareThe Chinese University of Hong KongHong KongChina

Climate change, especially as reflected in heat waves, is a rising threat worldwide. Appropriate use of cooling devices can protect people from health impacts during a heat wave. A population-based telephone survey was conducted in a representative sample of residents in Hong Kong to investigate ownership and use of domestic cooling devices, identify correlates, and examine their associations with risk perception of potential health impact of climate change. More than 90% of the 1002 respondents owned and used cooling devices at home. The majority(57.7%) perceived the potential health risk of climate change at a high level. However, risk perception had no relationship with ownership and utilization of cooling devices. Old people(≥ 65 years), the low-educated, those with low income, and those with chronic diseases were more likely not to use air conditioners when feeling *** findings suggest that there are no signs showing people have taken more protective actions although half of respondents recognized climate change as a threat. Familial economic condition may be a major determinant in ownership and use of air conditioners at home. Old people and those with chronic diseases are at high risk of adverse exposure to climate change and therefore should be equipped with appropriate measures to use cooling devices.

关键词： Climate change Domestic cooling device Heat wave health impact Hong Kong Risk perception

Spacing optimization of high power LED arrays for solid state lighting

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Journal of Semiconductors 2011年第1期32卷 45-49页

作者： y.Sing chan S.W.Ricky Lee Electronic Packaging Laboratory Center for Advanced Microsystems Packaging Hong Kong University of Science and Technology

This paper provides an analytical approach to determine the optimum pitch by utilizing a thermal resistance network, under the assumption of constant luminous efficiency. This work allows an LED array design which is mounted on a printed circuit board （PCB） attached with a heat sink subject to the natural convection cooling. Being validated by finite element （FE） models, the current approach can be shown as an effective method for the determination of optimal component spacing in an LED array assembly for SSL.

关键词： high power LED thermal resistance network finite element modeling

Pancreatic enzyme replacement therapy for pancreatic exocrine insufficiency in the 21^(st) century

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World Journal of Gastroenterology 2014年第33期20卷 11467-11485页

作者： Tony Trang Johanna chan David y Graham Department of Medicine Michael E. DeBakey Veterans Affairs Medical Center and Baylor College of Medicine Houston TX 77030 United States

Restitution of normal fat absorption in exocrine pancreatic insufficiency remains an elusive goal. Although many patients achieve satisfactory clinical results with enzyme therapy, few experience normalization of fat absorption, and many, if not most, will require individualized therapy. Increasing the quantity of lipase administered rarely eliminates steatorrhea but increases the cost of therapy. Enteric coated enzyme microbead formulations tend to separate from nutrients in the stomach precluding coordinated emptying of enzymes and nutrients. Unprotected enzymes mix well and empty with nutrients but are inactivated at pH 4 or below. We describe approaches for improving the results of enzyme therapy including changing to, or adding, a different product, adding non-enteric coated enzymes,(e.g., giving unprotected enzymes at the start of the mealand acid-protected formulations later), use of antisecretory drugs and/or antacids, and changing the timing of enzyme administration. Because considerable lipid is emptied in the first postprandial hour, it is prudent to start therapy with enteric coated microbead prior to the meal so that some enzymes are available during that first hour. Patients with hyperacidity may benefit from adjuvant antisecretory therapy to reduce the duodenal acid load and possibly also sodium bicarbonate to prevent duodenal acidity. Comparative studies of clinical effectiveness of different formulations as well as the characteristics of dispersion, emptying, and dissolution of enteric-coated microspheres of different diameter and density are needed; many such studies have been completed but not yet made public. We discuss the history of pancreatic enzyme therapy and describe current use of modern preparations, approaches to overcoming unsatisfactory clinical responses, as well as studies needed to be able to provide reliably effective therapy.

关键词： Pancreatic insufficiency Pancreatic enzyme replacement therapy Lipase Clinical trials Steator-rhea Fat malabsorption Chronic pancreatitis

Evolution of hepatitis B management in kidney transplantation

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World Journal of Gastroenterology 2014年第2期20卷 468-474页

作者： Desmond y H yap Tak Mao chan Division of Nephrology Department of MedicineQueen Mary Hospitalthe University of Hong Kong

Chronic hepatitis B virus(HBV)infection adversely influences the clinical outcomes of renal transplant recipients owing to increased hepatic *** of HBV infection in kidney transplant recipients presents a challenge to clinicians,especially in endemic *** precipitates renal allograft *** with lamivudine,the first oral nucleoside analogue available,resulted in effective viral suppression,reduced liver-related complications,and improved patient survival so that medium-term data showed comparable patient survival rates between hepatitis B surface antigen-positive and HBsAg-negative kidney transplant recipients in the era of effective antiviral *** has replaced lamivudine as first-line therapy for treatment-na?ve subjects in view of the propensity for drug resistance with the *** of HBV infection in kidney transplant patients needs to take into consideration the nephrotoxicity of nucleoside/tide analogues such as adefovir and *** of HBV-related complications in kidney transplant recipients starts much earlier prior to transplantation,with vaccination of patients with chronic kidney disease and donor-recipient matching with regard to HBV *** addition to anti-viral treatment,patients with chronic HBV infection must have regular surveillance for liver cancer and assessment for the development of cirrhosis.

关键词： Hepatitis B Kidney transplantation

Effects of Impurity on the Ground—State Transitions of a Quantum Dot in Strong Magnetic Field

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Communications in Theoretical Physics 2001年第6期35卷 735-739页

作者： K.S.chan E.y.B.PUN 等 DepartmentofPhysicsandMaterialsScience CityuniversityofHongKongHongKongChina DepartmentofElectronic

The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion.

关键词： impurity states quantum dots

Effect of terrain and building structures on the airflow in an airport

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第6期13卷 461-468页

作者： Dennis y. C. LEUNG W. y. LO W. y. CHOW P. W. chan Department of Mechanical Engineering The University of Hong Kong Hong Kong China Hong Kong Observatory Hong Kong China

The aim of this study was to perform computational fluid dynamics (CFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studied to explore the effects of turbulence on flying aircraft, especially during landing. The CFD simulation showed that significant differences in wind speeds may occur between the north and the south runways on the western part of the HKIA under typhoon conditions with a strong north to northwesterly wind. Simulation also showed that the hanger buildings between the two runways on the western side and the nearby terrain could be causing the observed difference in the wind speeds. The results also indicated that these obstacles could cause significant wind speed variations at the western end of the south runway. This may affect the operation of landing aircraft. The CFD results for a typical typhoon case were analyzed and found to match the wind data recorded by an aircraft landing that day.

关键词： Computational fluid dynamics (CFD) Hong Kong International Airport (HKIA) Low-level wind effect Hangars Terrain