1,910 research outputs found

    Spurious modulation on current-mode controlled dc/dc converters : an explanation for intermittent chaotic operation

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    Author name used in this publication: S. C. WongAuthor name used in this publication: C. K. TseAuthor name used in this publication: K. C. TamRefereed conference paper2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

    Novel D²T control for single-switch dual-output switching power converters

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    Author name used in this publication: C. K. TseAuthor name used in this publication: S. C. WongAuthor name used in this publication: K. C. TamRefereed conference paper2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

    An improved wavelet approach for finding steady-state waveforms of power electronics circuits using discrete convolution

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    Author name used in this publication: Chi K. TseAuthor name used in this publication: Kam C. Tam2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Fast analytical approach to finding steady-state waveforms for power electronics circuits using orthogonal polynomial basis functions

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    Author name used in this publication: K. C. TamAuthor name used in this publication: S. C. WongAuthor name used in this publication: C. K. TseRefereed conference paper2005-2006 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

    Mild iodine deficiency and thyroid disorders in Hong Kong.

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    OBJECTIVES: To review evidence of iodine deficiency and clinical thyroid disorders in Hong Kong. DATA SOURCES: Publications on local dietary iodine intake, the iodine content of local food items, and clinical thyroid problems in the Hong Kong population. DATA EXTRACTION: Data was extracted and evaluated independently by the authors. DATA SYNTHESIS: Iodine is an essential nutrient. Iodine deficiency can lead to goitre, hypothyroidism, mental deficiency, and impaired growth. It is now appreciated that determination of goitre incidence in children alone may grossly underestimate the problem of iodine deficiency in a population. In total, the evidence indicates that iodine deficiency exists in Hong Kong, leading to clinical problems of transient neonatal hypothyroidism, goitrogenesis, and thyroid disorders in pregnant women and neonates, as well as thyroid dysfunction in the elderly. CONCLUSION: A supplementation programme aimed at a relatively uniform iodine intake is recommended to avoid deficient or excessive iodine intake in subpopulations.published_or_final_versio

    Serum lipid and apolipoprotein distributions in Hong Kong Chinese

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    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

    Primitive neuroectodermal adrenal gland tumour

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    Ewing's sarcoma, also called primitive neuroectodermal tumour of the adrenal gland, is extremely rare. Only a few cases have been reported in the literature. We report on a woman with adult-onset primitive neuroectodermal tumour of the adrenal gland presenting with progressive flank pain. Computed tomography confirmed an adrenal tumour with invasion of the left diaphragm and kidney. Radical surgery was performed and the pain completely resolved; histology confirmed the presence of primitive neuroectodermal tumour, for which she was given chemotherapy. The clinical presentation of this condition is non-specific, and a definitive diagnosis is based on a combination of histology, as well as immunohistochemical and cytogenic analysis. According to the literature, these tumours demonstrate rapid growth and aggressive behaviour but there are no well-established guidelines or treatment strategies. Nevertheless, surgery remains the mainstay of local disease control; curative surgery can be performed in most patients. Adjuvant chemoirradiation has been advocated yet no consensus is available. The prognosis of patients with primitive neuroectodermal tumours remains poor.published_or_final_versio

    Associations of apolipoprotein E exon 4 and lipoprotein lipase S447X polymorphisms with acute ischemic stroke and myocardial infarction

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    Background: Because apolipoprotein E (apoE) and lipopoprotein lipase (LPL) polymorphisms interact with each other and with other factors to affect lipid metabolism, we sought to determine their separate and combined effects in association with ischemic vascular disease. Methods: We performed a case-control study of 816 subjects: 246 acute ischemic stroke patients, 234 acute myocardial infarction patients, and 336 controls. APOE exon 4 and LPL S447X genotypes were determined. Results: APOE ε2 and ε4 homozygotes were increased in stroke (4.5% vs. 1.0%, p = 0.008), while in myocardial infarction the ε4 allele was increased (12.6% vs. 9.5%, p = 0.006) but ε2 was decreased (3.7% vs. 12.1%, p = 0.000006). For subjects with either APOE ε2 or ε4 alleles, LPL X alleles were increased in vascular disease (OR = 2.2, p = 0.01). LPL X alleles displayed opposite tendencies toward association with disease when subjects were divided by sex, smoking, or APOE genotype. Meta-analysis and regression analysis of previous studies supported the sex and smoking dichotomies. Conclusion: This is the first report of an association of vascular disease with an interaction of APOE exon 4 and LPL S447X genotypes. Therefore, APOE genotypes and LPL S447X interactions with apoE, sex, and smoking may affect the risk of myocardial infarction and ischemic stroke. © 2006 by Walter de Gruyter.published_or_final_versio
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