A new Kalman filter-based power spectral density estimation for nonstationary pressure signals

IEEE International Symposium on Circuits and Systems, Island of Kos, Greece, 21-24 May 2006This paper presents a new Kalman filter-based power spectral density estimation (PSD) algorithm for nonstationary pressure signals. The pressure signal is assumed to be an autoregressive (AR) process, and a stochastically perturbed difference equation constraint model is used to describe the dynamics of the AR coefficients. The proposed Kalman filter frame uses variable number of measurements to estimate the time-varying AR coefficients and yield the PSD estimation with better time-frequency resolution. Simulation results show that the proposed algorithm achieves a better time-frequency resolution than conventional algorithms for nonstationary pressure signals. © 2006 IEEE.published_or_final_versio

Approximate QR-based algorithms for recursive nonlinear least squares estiamtion

This paper proposes new approximate QR-based algorithms for recursive nonlinear least squares (NLS) estimation. Two QR decomposition-based recursive algorithms are introduced based on the classical Gauss-Newton (GN) and Levenberg-Marquardt (LM) algorithms in nonlinear unconstrained optimization or least squares problems. Instead of using the matrix inversion formula, recursive QR decomposition is employed, which is known to be numerically more stable in finite wordlength implementation. A family of p-A-QR-LS algorithms is then proposed to solve the LS problem resulting from the linearization of the NLS problem. It achieves different complexity-performance tradeoffs by retaining different number of diagonal plus off-diagonals (denoted by an integer p) of the triangular factor of the augmented data matrix. Simulation results on identifying a nonlinear perceptron are provided to illustrate the principle of the new algorithms. © 2005 IEEE.published_or_final_versio

Techniques for improving block error rate of LDPC decoders

Author name used in this publication: F. C. M. LauAuthor name used in this publication: C. K. TseAuthor name used in this publication: S. C. WongRefereed conference paper2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

The Hong Kong second parking demand study

This paper describes the background, objectives, surveys, models, findings and recommendations of the Hong Kong second parking demand study. This study aims to give strategic directions to guide the planning and management of parking facilities in Hong Kong. It comprises extensive surveys to determine the parking inventory, parking characteristics and driver behaviour. Demand models were developed to predict the future night-time and daytime parking demand over a planning horizon of 15 years. All types of vehicle, including private cars, taxis, motorcycles, coaches and goods vehicles, were included in the analysis. The recommendations of a previous parking demand study have been reviewed, and new recommendations are given.published_or_final_versio

Age-dependent alterations of cigarette smoke-induced oxidative and inflammatory responses in rats

Oral PresentationBACKGROUND: Cigarette smoking (CS) is a leading cause of chronic obstructive pulmonary disease (COPD). The prevalence of COPD is much higher among the elderly. However, the impact of early-age CS exposure on CS induced COPD is unknown. This study aimed to investigate whether CS-induced oxidative and inflammatory responses were ...published_or_final_versionThe 17th Medical Research Conference, Department of Medicine, The University of Hong Kong, Hong Kong, 14 January 2012. In Hong Kong Medical Journal, 2012, v. 18 n. 1, suppl. 1, p. 39, abstract no. 5

Efficacy of a pre-S containing vaccine in patients receiving lamivudine prophylaxis after liver transplantation for chronic hepatitis B

Lamivudine monoprophylaxis against hepatitis B virus (HBV) reinfection after liver transplantation is associated with recurrence due to escape mutants and second generation recombinant HBV vaccine is not effective. We studied the efficacy of two courses each of three double-doses (20 ug) of third-generation recombinant pre-S containing vaccine (Sci-B-Vac™) in 20 patients on lamivudine prophylaxis at a median of 637 days (range, 390-2666 days) after transplantation. At enrollment, all patients were seronegative for HBsAg, anti-HBs and HBVDNA (by qPCR). Lamivudine (100 mg/day) was continued throughout the study. Five patients (25%) responded to the first course and five additional patients responded after the second course (overall response rate 50%). The response rate was 88% in patients younger than 50 years old and 25% in older patients (p = 0.02). The median peak anti-HBs titer was 153 mIU/mL with six responders having a titer >100 mIU/mL and seven sustained >6 months. Among seven previous nonresponders to second generation recombinant vaccine, three (44%) responded. At the end of the study, all patients remained seronegative for HBsAg. In conclusion, Sci-B-Vac™ is effective in about 50% of patients receiving lamividine prophylaxis and may prevent recurrence due to escape mutants. © 2006 The Authors.postprin

《洪武正韻》，《洪武正韻譯訓》韻字字樣異同的考察

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Serum lipid and apolipoprotein distributions in Hong Kong Chinese

STUDY OBJECTIVE--The aim was to describe the distribution of lipids and apolipoproteins in the Chinese population in Hong Kong. DESIGN--This was a prospective, cross sectional, population based survey. SETTINGS--The study was conducted in a single, self referred, out patient screening centre. PARTICIPANTS--Altogether 825 Chinese adults aged > or = 20 years were screened. One hundred subjects who had previously had lipid measurement and 29 who were taking lipid modifying drugs were excluded but 289 men and 407 women remained for further analysis. MAIN RESULTS--Age standardised mean (SEM) lipids concentrations for Hong Kong Chinese were total cholesterol: men, 5.48 (0.05) mmol/l and women, 5.46 (0.06) mmol/l; triglycerides: men, 1.22 (1.03) mmol/l and women, 1.00 (1.03) mmol/l; high density lipoprotein (HDL) cholesterol: men, 1.25 (0.02) mmol/l and women, 1.42 (0.02) mmol/l; low density lipoprotein (LDL) cholesterol: men, 3.56 (0.05) mmol/l and women, 3.50 (0.06) mmol/l; apolipoprotein A-I (apo A-I): men, 1.34 (0.01) g/l and women, 1.46 (0.01) g/l; and apolipoprotein B (apo B): men, 1.15 (0.02) g/l and women, 1.06 (0.02) g/l. The total to HDL cholesterol ratios were men, 4.62 (0.07) and women, 4.10 (0.08); and apo B to apo A-I ratios (apo B/A) were men, 0.88 (0.02) and women, 0.75 (0.02). While levels of total cholesterol, LDL cholesterol, apo B, triglycerides, total/HDL cholesterol, and apo B/A were positively associated with age in both sexes and were higher in men before the age 50-59 years, they rose steeply thereafter in women to cross over the levels in men. In contrast, HDL cholesterol decreased with age while apo A-I remained constant, and both were consistently higher in women than in men in all age groups. CONCLUSIONS--Hong Kong Chinese have attained lipid profiles similar to those in other developed western populations. Environmental factors seem influential in this regard. Faced with the increasing coronary mortality of recent years, there should be a major effort to reduce the cholesterol concentrations in this population.published_or_final_versio

Age as a factor in severe bacterial infection in transfusion-dependent patients with thalassemia major [2] (multiple letters)

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Prevalence of drugged drivers among non-fatal driver casualties presenting to a trauma centre in Hong Kong

OBJECTIVE: To investigate the prevalence and characteristics of abusive drug exposure among non-fatal motor vehicle driver casualties presenting to a designated trauma centre in Hong Kong. DESIGN: Cross-sectional study. SETTING: Designated trauma centre/regional accident and emergency department in Hong Kong. SUBJECTS: Non-fatal motor vehicle driver casualties who presented to the trauma centre from 1 January 2007 to 31 December 2007. MAIN OUTCOME MEASURES: Screening of abusive drug exposure using commercial bedside urine immunoassay kits. RESULTS: Drug screening was performed in 395 injured drivers, 10% of whom tested positive for the drugs of interest. Ketamine was the most commonly detected abusive substance (found in 45% of the subjects). A significantly higher proportion of young drivers (aged <25 years) screened positive (odds ratio=2.3; 95% confidence interval, 1.0-5.2; P=0.04), with the rate being 21%. The presence of these drugs in urine was related to the time of occurrence of the crash; those occurring between midnight and dawn revealed a trend towards a higher proportion of casualties testing drug-positive (odds ratio=2.2; 95% confidence interval, 0.9-5.3; P=0.07). There were no significant differences in the frequency of persons testing positive for the screened drugs with respect to gender, class of motor vehicle driven, or the day of the week on which the crash occurred. CONCLUSIONS: The prevalence of drugged driving among non-fatal casualties in our series of Hong Kong drivers was 10%. The frequency of such drivers testing positive for drugs was significantly higher in persons aged less than 25 years. These findings indicate a need to amend existing laws and implement on-site drug screening for suspected drugged drivers.published_or_final_versio