2,840 research outputs found
Large values of error terms of a class of arithmetical functions
We consider the error terms of a class of arithmetical functions whose Dirichlet series satisfy a functional equation with multiple gamma factors. Our aim is to establish Ω± results to a subclass of these arithmetical functions with a good localization of the occurrence of the extreme values. As applications, we improve the Ω± results of some special 3-dimensional ellipsoids of other writers and extend our result to other ellipsoids.published_or_final_versio
On the mean square formula of the error term in the Dirichlet divisor problem
Let F(x) be the remainder term in the mean square formula of the error term (t) in the Dirichlet divisor problem. We improve on the upper estimate of F(x) obtained by Preissmann around twenty years ago. The method is robust, which applies to the same problem for the error terms in the circle problem and the mean square formula of the Riemann zeta-function. © Cambridge Philosophical Society 2008.postprin
香港的選擇性墮胎: 合法與否?
There is legal uncertainty as to whether selective foeticide is authorised under section 47A of the Offences Against the Person Ordinance (1967). Medical and legal issues surrounding a case of selective foeticide in a triplet pregnancy are reported.published_or_final_versio
Effects of oxidation temperature on Ga 2O3 film thermally grown on GaN
The effects of oxidation temperature on thermally oxidized GaN film were investigated. The GaN wafers were oxidzied at 750 °C, 800 °C and 850 °C respectively. The electrical characteristics and interface quality of MOS capacitors were compared among different oxidation temperatures. The sample oxidized at 800 °C presented best current-voltage, capacitance-voltage characteristics and smoothest surface morphology, while the higher oxidation temperature of 850 °C gave best interface quality. The electrical breakdown field was increased by one order of magnitude when the sample was oxidized at 800 °C as compared with 750 °C and 850 °C. Lastly, after the sample oxidized at 800 °C was annealed at 850 °C for 10 min, the quality of its oxide was significantly degraded. © 2005 IEEE.published_or_final_versio
Sudden cardiac death: Prevention and treatment
Sudden cardiac death remains a major health issue in western countries as well as in Hong Kong. Despite increasing knowledge of the mechanisms and risk factors of sudden cardiac death, methods for identifying high-risk candidates and predicting the efficacy of measures to prevent sudden cardiac death are still inadequate. A significant proportion of patients have known heart disease but are generally considered to be at low risk for this event. More efforts are needed to improve the success rate of out-of-hospital resuscitation through better warning systems, the use of amiodarone for refractory arrhythmias, and the widespread availability of automated defibrillation devices to allow early defibrillation. It is likely that these measures could increase the number of survivors following cardiac arrest. In survivors of sudden cardiac death episodes, treatment of the underlying cardiac disease, especially early revascularisation for myocardial ischaemia, is required. In the majority of patients, implantation of an implantable cardioverter defibrillator, with or without the use of an anti-arrhythmic drug such as amiodarone, would then be used to maintain survival. Furthermore, for individuals at significant risk of sudden cardiac death, primary prevention of sudden cardiac death through the placement of an implantable cardioverter defibrillator is increasingly being used.published_or_final_versio
Alterations in Gastric Microbiota After H. Pylori Eradication and in Different Histological Stages of Gastric Carcinogenesis
The role of bacteria other than Helicobacter pylori (HP) in the stomach remains elusive. We characterized the gastric microbiota in individuals with different histological stages of gastric carcinogenesis and after receiving HP eradication therapy. Endoscopic gastric biopsies were obtained from subjects with HP gastritis, gastric intestinal metaplasia (IM), gastric cancer (GC) and HP negative controls. Gastric microbiota was characterized by Illumina MiSeq platform targeting the 16 S rDNA. Apart from dominant H. pylori, we observed other Proteobacteria including Haemophilus, Serratia, Neisseria and Stenotrophomonas as the major components of the human gastric microbiota. Although samples were largely converged according to the relative abundance of HP, a clear separation of GC and other samples was recovered. Whilst there was a strong inverse association between HP relative abundance and bacterial diversity, this association was weak in GC samples which tended to have lower bacterial diversity compared with other samples with similar HP levels. Eradication of HP resulted in an increase in bacterial diversity and restoration of the relative abundance of other bacteria to levels similar to individuals without HP. In conclusion, HP colonization results in alterations of gastric microbiota and reduction in bacterial diversity, which could be restored by antibiotic treatment.published_or_final_versio
Optical characteristics of GAN/SI micro-pixel light-emitting diode arrays
Two-dimensional arrays of emissive micro-light-emitting diodes (μ-LEDS) have been developed for a variety of applications such as high resolution micro-displays, maskless photo-lithography and multichannel visible-light optical communications amongst others. μ-LEDs have traditionally been
fabricated on InGaN LED wafers grown on transparent sapphire substrates, and have suffered from optical crosstalk issues. When a single pixel is addressed, adjacent pixels and regions appear
illuminated simultaneously. Such problems could result in functional failure in high-density μ-LED
applications, including reduced resolution of micro-display and decreased signal-to-noise ratio in ...postprin
Immunogenetics in SARS: a case-control study.
Key Messages:
1. Human leukocyte antigen (HLA) genotypes from 102 SARS patients (susceptible) and 108 SARS contacts
(resistant) were obtained.
2. Allelic frequencies of the Class I (HLA-A, -B, and -Cw) and Class II (HLA-DR and -DQ) genes from these
genetically unrelated subjects were compared.
3. A significantly higher frequency of DRB4*01010101 was found in the SARS-susceptible than SARS-resistant
group. In contrast, significantly higher frequencies of HLA-B*1502 and HLADRB3*030101 were found
in the SARS-resistant than SARSsusceptible group. However, none of these associations was significant after Bonferroni correction. Further, analysis of 10/36 genetically related families did not reveal any HLA alleles associated with SARS susceptibility or resistance.
4. We could not confirm previous findings of an HLA association with susceptibility or resistance to SARS. The significance of these associations needs to be validated by further independent studies.published_or_final_versio
Comparative genomic analysis of pre-epidemic and epidemic Zika virus strains for virological factors potentially associated with the rapidly expanding epidemic
published_or_final_versio
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