Wind flow in the recessed cavities of a tall building

Fulltext in: http://www.iawe.org/Proceedings/7APCWE/M3D_3.pdfTechnical Session: M3-D Computational Wind Engineering (2), no.3In a congested city like Hong Kong, residential tall buildings are often built with an irregular plan form and with a number of apartments arranged as wing sections extending from a central core. To provide views and sufficient ventilation to the apartments, deeply recessed cavities are placed between adjacent building wings. This paper reports a CFD study of the wind-induced flow inside a recessed cavity of a tall building with an objective to assess the adequacy of ventilation inside the cavity. The dimensions of the cavity are varied systematically to investigate the flow exchange between the cavity and the outside at different heights. It is found that the flow inside the cavity is not a simple cross flow or a stagnation flow. Flow exchange takes place in different directions along the building heights.link_to_subscribed_fulltex

Does varicocele repair improve conventional semen parameters? A meta-analytic study of before-after data

Purpose The purpose of this meta-analysis is to study the impact of varicocele repair in the largest cohort of infertile males with clinical varicocele by including all available studies, with no language restrictions, comparing intra-person conventional semen parameters before and after the repair of varicoceles. Materials and Methods The meta-analysis was performed according to PRISMA-P and MOOSE guidelines. A systematic search was performed in Scopus, PubMed, Cochrane, and Embase databases. Eligible studies were selected according to the PICOS model (Population: infertile male patients with clinical varicocele; Intervention: varicocele repair; Comparison: intra-person before-after varicocele repair; Outcome: conventional semen parameters; Study type: randomized controlled trials [RCTs], observational and case-control studies). Results Out of 1,632 screened abstracts, 351 articles (23 RCTs, 292 observational, and 36 case-control studies) were included in the quantitative analysis. The before-and-after analysis showed significant improvements in all semen parameters after varicocele repair (except sperm vitality); semen volume: standardized mean difference (SMD) 0.203, 95% CI: 0.129–0.278; p<0.001; I2=83.62%, Egger’s p=0.3329; sperm concentration: SMD 1.590, 95% CI: 1.474–1.706; p<0.001; I2=97.86%, Egger’s p<0.0001; total sperm count: SMD 1.824, 95% CI: 1.526–2.121; p<0.001; I2=97.88%, Egger’s p=0.0063; total motile sperm count: SMD 1.643, 95% CI: 1.318–1.968; p<0.001; I2=98.65%, Egger’s p=0.0003; progressive sperm motility: SMD 1.845, 95% CI: 1.537%–2.153%; p<0.001; I2=98.97%, Egger’s p<0.0001; total sperm motility: SMD 1.613, 95% CI 1.467%–1.759%; p<0.001; l2=97.98%, Egger’s p<0.001; sperm morphology: SMD 1.066, 95% CI 0.992%–1.211%; p<0.001; I2=97.87%, Egger’s p=0.1864. Conclusions The current meta-analysis is the largest to date using paired analysis on varicocele patients. In the current meta-analysis, almost all conventional semen parameters improved significantly following varicocele repair in infertile patients with clinical varicocele. Keywords Controlled before-after studies; Infertility, male; Meta-analysis; Varicocel

Aspirin effect on virulence of Candida albicans in stroke sufferers

Research Poster II: abstract no. 0054Oral carriage rate of Candida albicans in stroke sufferers on aspirin was found to be lower than their non-aspirin counterpart. Although aspirin has a direct inhibitory effect on Candida albicans, the exact mechanism leading to a lower carriage rate is still unknown. Objectives: 1) To determine the adhesion of Candida albicans to buccal epithelial cells and the phospholipase, proteinase and haemolytic activities in stroke sufferers, and 2) To investigate the correlations between these virulence factors. Methods: Nineteen C. albicans isolates were obtained from stroke sufferers on aspirin. Four reference strains isolated from non-stroke sufferers served as control. The isolates were tested for in vitro phospholipase, proteinase and haemolytic activities using three different plate assays. Adhesion to buccal epithelial cells was determined by an established adhesion assay. Results: No significant different in phospholipase activities was found between the test group and the control. Higher proteinase and haemolytic activities were found in the test group (P < 0.001) and adhesion was higher in the control (P <0.001). Adhesion was correlated with proteinase and haemolytic activities (P < 0.001). Conclusions: These data provide evidence of altered extracellular enzyme activities in Candida isolates taken from stroke sufferers on aspirin. The higher proteinase and haemolytic activities in the aspirin group could be a compensatory mechanism for the attenuated Candida in order to maintain its virulence in the host environment.link_to_OA_fulltextThe 24th Annual Scientific Meeting of the IADR-SEA Division, Taipei, Taiwan, 19-21 September 2010

Effects of building wall arrangements on wind-induced ventilation through the refuge floor of a tall building

Wind-induced natural ventilation plays an important role in the fire and smoke safety of a refuge floor. This paper reports a computational fluid dynamics study to investigate the effect of building wall arrangements on the amount of wind-induced ventilation through a refuge floor which is located at the building mid-height. The refuge floor analysed has a large service core at its centre and is surrounded by exterior building walls, which are arranged in nine configurations that represent varying degrees of opening to wind flow. Results of computed flow patterns show that the wind-induced natural ventilation rate of a refuge floor varies significantly depending on the number of enclosing external walls and the incidence wind angle. A refuge floor, having only one side open, results in the worst natural ventilation and is not recommended. © 2008 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

A CFD study of Hong Kong refuge floor design: floor height effect

Since 1996, the provision of a refuge floor has been a mandatory feature for all new tall buildings in Hong Kong. These floors are designed to provide for the building occupants a fire safe environment that is also free from smoke. However, the desired cross ventilation on these floors to achieve the removal of smoke, assumed by the Building Codes of Hong Kong, is still being questioned so that a further scientific study of the wind-induced ventilation of a refuge floor is needed. This paper presents an investigation into this issue. The developed computational technique used in this paper was adopted to study the wind-induced natural ventilation on a refuge floor. The aim of the investigation was to establish whether a refuge floor with a central core and having cross ventilation produced by only two open opposite external side walls on the refuge floor would provide the required protection in all situations taking into account behaviour of wind due to different floor heights, wall boundary conditions and turbulence intensity profiles. The results revealed that natural ventilation can be increased by increasing the floor height provided the wind angle to the building is less than 90°. The effectiveness of the solution was greatly reduced when the wind was blowing at 90° to the refuge floor opening.link_to_subscribed_fulltex

Expression of an abnormal sized c-kit transcript in Hong Kong Chinese acute lymphoblastic leukaemia patients

Blast cells from a majority of acute myelogenous leukaemia (AML) patients express c-kit mRNA. However, c-kit expression has not been observed in patients with acute lymphoblastic leukaemia (ALL) and lymphoproliferative disease. We report here the detection of an abnormal sized c-kit mRNA in two Hong Hong Chinese patients with pre-B ALL and common ALL.link_to_subscribed_fulltex

Comparative host gene transcription by microarray analysis early after infection of the Huh7 cell line by severe acute respiratory syndrome coronavirus and human coronavirus 229E

The pathogenesis of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) at the cellular level is unclear. No human cell line was previously known to be susceptible to both SARS-CoV and other human coronavinises. Huh7 cells were found to be susceptible to both SARS-CoV, associated with SARS, and human coronavirus 229E (HCoV-229E), usually associated with the common cold. Highly lytic and productive rates of infections within 48 h of inoculation were reproducible with both viruses. The early transcriptional profiles of host cell response to both types of infection at 2 and 4 h postinoculation were determined by using the Affymetrix HG-U133A microarray (about 22,000 genes). Much more perturbation of cellular gene transcription was observed after infection by SARS-CoV than after infection by HCoV-229E. Besides the upregulation of genes associated with apoptosis, which was exactly opposite to the previously reported effect of SARS-CoV in a colonic carcinoma cell line, genes related to inflammation, stress response, and procoagulation were also upregulated. These findings were confirmed by semiquantitative reverse transcription-PCR, reverse transcription-quantitative PCR for mRNA of genes, and immunoassays for some encoded proteins. These transcriptomal changes are compatible with the histological changes of pulmonary vasculitis and microvascular thrombosis in addition to the diffuse alveolar damage involving the pneumocytes. Copyright © 2005, American Society for Microbiology. All Rights Reserved.link_to_OA_fulltex