325 research outputs found

    Web Crippling Strength of Cold-Formed Duplex Stainless Steel Lipped-Channel Sections with Web Openings Subjected to Interior-One-Flange Loading

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    Cold-formed stainless steel sections are becoming more widely used in the residential and commercial sectors due to their high corrosion resistance and high strength-to-weight ratio. However, their susceptibility to web crippling at points of concentrated loading is well-known to be an important design issue. In addition, web openings are also become popular, as they improve ease of installation of services. This paper presents the results of an investigation into the effect of web crippling on cold-formed duplex stainless steel lipped channel-sections, having such openings, under the interior-one-flange (IOF) loading condition. 742 non-linear elasto-plastic finite element analyses are undertaken, with web openings located either centred beneath the bearing plate or offset to bearing plate. The effect of the size of the web opening, length of bearing plate and location of the web opening is considered. Strength reduction factor equations are proposed, that can be used to take into account such openings in design

    Web crippling behaviour of cold-formed steel channel sections with web holes subjected to Interior-one-flange loading condition-part I: experimental and numerical investigation

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    Web openings are increasingly used in cold-formed steel beam members of buildings to facilitate ease of services. In this paper, a combination of tests and non-linear finite element analyses is used to investigate the effect of such holes on web crippling under the interior-one-flange (IOF) loading condition; the cases of both flange fastened and flange unfastened to the bearing plate are considered. The results of 61 web crippling tests are presented, with 18 tests conducted on channel sections without web openings and 43 tests conducted on channel sections with web openings. In the case of the tests with web openings, the hole was either located centred beneath the bearing plate or having a horizontal clear distance to the near edge of the bearing plate. A good agreement between the tests and finite element analyses was obtained in term of both strength and failure modes

    Observational consequences of fine structure line optical depths on infrared spectral diagnostics

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    It has long been known that infrared fine structure lines of abundant ions, like the [O III] 88 micron line, can become optically thick in H II regions under certain high luminosity conditions. This could mitigate their potential as diagnostic tools, especially if the source is too dusty for optical spectroscopy to otherwise determine the system's parameters. We examined a series of photoionization calculations which were designed to push the nebulae into the limit where many IR lines should be quite optically thick. We find that radiative transfer effects do not significantly change the observed emission line spectrum. This is due to a combination of grain absorption of the hydrogen ionizing continuum and the fact that the correction for stimulated emission in these lines is large. Given these results, and the likelihood that real objects have non-thermal line broadening, it seems unlikely that line optical depth presents a problem in using these lines as diagnostics of the physical conditions or chemical composition.Comment: 16 pages, 4 figures, to be published in the February 2003 issue of the PAS

    Co-infection of Haemonchus contortus and Trichostrongylus spp. among livestock in Malaysia as revealed by amplification and sequencing of the internal transcribed spacer II DNA region

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    Background: Haemonchus contortus and Trichostrongylus spp. are reported to be the most prevalent and highly pathogenic parasites in livestock, particularly in small ruminants. However, the routine conventional tool used in Malaysia could not differentiate the species accurately and therefore limiting the understanding of the co-infections between these two genera among livestock in Malaysia. This study is the first attempt to identify the strongylids of veterinary importance in Malaysia (i.e., H. contortus and Trichostrongylus spp.) by amplification and sequencing of the Internal Transcribed Spacer II DNA region. Results: Overall, 118 (cattle: 11 of 98 or 11.2%; deer: 4 of 70 or 5.7%; goats: 99 of 157 or 63.1%; swine: 4 of 91 or 4.4%) out of the 416 collected fecal samples were microscopy positive with strongylid infection. The PCR and sequencing results demonstrated that 93 samples (1 or 25.0% of deer; 92 or 92.9% of goats) contained H. contortus. In addition, Trichostrongylus colubriformis was observed in 75 (75.8% of 99) of strongylid infected goats and Trichostrongylus axei in 4 (4.0%) of 99 goats and 2 (50.0%) of 4 deer. Based on the molecular results, co-infection of H. contortus and Trichostrongylus spp. (H. contortus + T. colubriformis denoted as HTC; H. contortus + T. axei denoted as HTA) were only found in goats. Specifically, HTC co-infections have higher rate (71 or 45.2% of 157) compared to HTA co-infections (3 or 1.9% of 157). Conclusions: The present study is the first molecular identification of strongylid species among livestock in Malaysia which is essential towards a better knowledge of the epidemiology of gastro-intestinal parasitic infection among livestock in the country. Furthermore, a more comprehensive or nationwide molecular-based study on gastro-intestinal parasites in livestock should be carried out in the future, given that molecular tools could assist in improving diagnosis of veterinary parasitology in Malaysia due to its high sensitivity and accurac

    Malaria after international travel: a GeoSentinel analysis, 2003-2016.

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    BACKGROUND: More than 30,000 malaria cases are reported annually among international travellers. Despite improvements in malaria control, malaria continues to threaten travellers due to inaccurate perception of risk and sub-optimal pre-travel preparation. METHODS: Records with a confirmed malaria diagnosis after travel from January 2003 to July 2016 were obtained from GeoSentinel, a global surveillance network of travel and tropical medicine providers that monitors travel-related morbidity. Records were excluded if exposure country was missing or unascertainable or if there was a concomitant acute diagnosis unrelated to malaria. Records were analyzed to describe the demographic and clinical characteristics of international travellers with malaria. RESULTS: There were 5689 travellers included; 325 were children <18 years. More than half (53%) were visiting friends and relatives (VFRs). Most (83%) were exposed in sub-Saharan Africa. The median trip duration was 32 days (interquartile range 20-75); 53% did not have a pre-travel visit. More than half (62%) were hospitalized; children were hospitalized more frequently than adults (73 and 62%, respectively). Ninety-two per cent had a single Plasmodium species diagnosis, most frequently Plasmodium falciparum (4011; 76%). Travellers with P. falciparum were most frequently VFRs (60%). More than 40% of travellers with a trip duration ≤7 days had Plasmodium vivax. There were 444 (8%) travellers with severe malaria; 31 children had severe malaria. Twelve travellers died. CONCLUSION: Malaria remains a serious threat to international travellers. Efforts must focus on preventive strategies aimed on children and VFRs, and chemoprophylaxis access and preventive measure adherence should be emphasized

    Failure to prescribe pneumocystis prophylaxis is associated with increased mortality, even in the cART era: results from the Treat Asia HIV observational database

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    <p>Abstract</p> <p>Background</p> <p>Pneumocystis jiroveci pneumonia (PCP) prophylaxis is recommended for patients with CD4 counts of less than 200 cells/mm<sup>3</sup>. This study examines the proportion of patients in the TREAT Asia HIV Observational Database (TAHOD) receiving PCP prophylaxis, and its effect on PCP and mortality.</p> <p>Methods</p> <p>TAHOD patients with prospective follow up had data extracted for prophylaxis using co-trimoxazole, dapsone or pentamidine. The proportion of patients on prophylaxis was calculated for each calendar year since 2003 among patients with CD4 counts of less than 200 cells/mm<sup>3</sup>. The effect of prophylaxis on PCP and survival were assessed using random-effect Poisson regression models.</p> <p>Results</p> <p>There were a total of 4050 patients on prospective follow up, and 90% of them were receiving combination antiretroviral therapy. Of those with CD4 counts of less than 200 cells/mm<sup>3</sup>, 58% to 72% in any given year received PCP prophylaxis, predominantly co-trimoxazole. During follow up, 62 patients developed PCP (0.5 per 100 person-years) and 169 died from all causes (1.36/100 person-years). After stratifying by site and adjusting for age, CD4 count, CDC stage and antiretroviral treatment, those without prophylaxis had no higher risk of PCP, but had a significantly higher risk of death (incident rate ratio 10.8, p < 0.001). PCP prophylaxis had greatest absolute benefit in patients with CD4 counts of less than 50 cells/mm<sup>3</sup>, lowering mortality rates from 33.5 to 6.3 per 100 person-years.</p> <p>Conclusions</p> <p>Approximately two-thirds of TAHOD patients with CD4 counts of less than 200 cells/mm<sup>3 </sup>received PCP prophylaxis. Patients without prophylaxis had significantly higher mortality, even in the era of combination ART. Although PCP may be under-diagnosed, these data suggest that prophylaxis is associated with important survival benefits.</p

    Differential diagnosis of illness in travelers arriving from sierra Leone, Liberia, or guinea: A cross-sectional study from the Geosentinel surveillance network

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    Background: The largest-ever outbreak of Ebola virus disease (EVD), ongoing in West Africa since late 2013, has led to export of cases to Europe and North America. Clinicians encountering ill travelers arriving from countries with widespread Ebola virus transmission must be aware of alternate diagnoses associated with fever and other nonspecific symptoms. Objective: To define the spectrum of illness observed in persons returning from areas of West Africa where EVD transmission has been widespread. Design: Descriptive, using GeoSentinel records. Setting: 57 travel or tropical medicine clinics in 25 countries. Patients: 805 ill returned travelers and new mmigrants from Sierra Leone, Liberia, or Guinea seen between September 2009 and August 2014. Measurements: Frequencies of demographic and travelrelated characteristics and illnesses reported. Results: The most common specific diagnosis among 770 nonimmigrant travelers was malaria (n = 310 [40.3%]), with Plasmodium falciparum or severe malaria in 267 (86%) and non–P. falciparum malaria in 43 (14%). Acute diarrhea was the second most common diagnosis among nonimmigrant travelers (n= 95 [12.3%]). Such common diagnoses as upper respiratory tract infection, urinary tract infection, and influenza-like illness occurred in only 26, 9, and 7 returning travelers, respectively. Few instances of typhoid fever (n = 8), acute HIV infection (n = 5), and dengue (n = 2) were encountered. Limitation: Surveillance data collected by specialist clinics may not be representative of all ill returned travelers. Conclusion: Although EVD may currently drive clinical evaluation of ill travelers arriving from Sierra Leone, Liberia, and Guinea, clinicians must be aware of other more common, potentially fatal diseases. Malaria remains a common diagnosis among travelers seen at GeoSentinel sites. Prompt exclusion of malaria and other life-threatening conditions is critical to limiting morbidity and mortality
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