45,188 research outputs found

    Approach to Fungal Infections in Human Immunodeficiency Virus-Infected Individuals Pneumocystis and Beyond

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    Many fungi cause pulmonary disease in HIV-infected patients. Major pathogens include Pneumocystis jirovecii, Cryptococcus neoformans, Aspergillus species, Histoplasma capsulatum, Coccidioides species, Blastomyces dermatitidis, Paracoccidioides brasiliensis, Talaromyces marneffei, and Emmonsia species. Because symptoms are frequently non-specific, a high index of suspicion for fungal infection is required for diagnosis. Clinical manifestations of fungal infection in HIV-infected patients frequently depend on the degree of immunosuppression and the CD4 + TH cell count. Establishing definitive diagnosis is important because treatments differ. Primary and secondary prophylaxis depends on CD4+ TH cell counts as well as geographic location and local prevalence of disease

    Modelling of GTAW Weld Pool under Marangoni Convection

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    With several different fusion welding processes, the melted weld pool profile which ultimately solidifies to form the fusion zone, diverging greatly by a wide variety of factors, e.g. base material, workpiece size, machine setups and extensive range of other process variables. For each distinctive welding setup, the weld pool geometry could vary considerably, and thought to be largely dependent on the hydrodynamics of the weld pools [1]. The Marangoni Effect or thermo-capillarity is seen to be the a dominant force influencing weld pool flow patterns under Gas Tungsten Arc Welding (GTAW), inducing liquid metal to flow to regions with higher surface tension (γ) caused by surface tension thermal gradients ∂γ⁄∂T, this in turn would greatly alter the weld pool thermal history, hence the fusion zone geometry [2]. As a general trend, for a negative ∂γ⁄∂T, outward flow from the pool centre to the edge tends to produce wide and shallow pools; whereas for a positive ∂γ⁄∂T, the liquid metal would flow inward to the pool centre, thus creating deep and narrow pool shapes [3]. Fig. 1 Schematic illustration of GTAW process with negative surface tension temperature gradient. This research group believes that the Marangoni Effect is the dominant force in weld pool shaping. To better understand the weld pool behaviours, a two-dimensional simulation model was constructed in CFD package Fluent®, based on stationary arc GTAW welding conditions. In addition, GTAW welding experiments were also performed on titanium alloy Ti-5Al-5Mo-5V-3Cr as reference data for the numerical results to evaluate against

    Sparse principal component analysis via axis-aligned random projections

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    We introduce a new method for sparse principal component analysis, based on the aggregation of eigenvector information from carefully-selected axis-aligned random projections of the sample covariance matrix. Unlike most alternative approaches, our algorithm is non-iterative, so is not vulnerable to a bad choice of initialisation. We provide theoretical guarantees under which our principal subspace estimator can attain the minimax optimal rate of convergence in polynomial time. In addition, our theory provides a more refined understanding of the statistical and computational trade-off in the problem of sparse principal component estimation, revealing a subtle interplay between the effective sample size and the number of random projections that are required to achieve the minimax optimal rate. Numerical studies provide further insight into the procedure and confirm its highly competitive finite-sample performance.The research of the first and third authors was supported by an Engineering and Physical Sciences Research Council (EPSRC) grant EP/N014588/1 for the centre for Mathematical and Statistical Analysis of Multimodal Clinical Imaging. The second and third authors were supported by EPSRC Fellowship EP/J017213/1 and EP/P031447/1, and grant RG81761 from the Leverhulme Trust

    Sensitivity of activated human lymphocytes to cyclosporine and its metabolites

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    Alloreactive T cells generated as clones from mixed lymphocyte cultures, or propagated from heart or liver transplant biopsies, were tested for secondary proliferation measured in the primed lymphocyte test in the presence of Cyclosporine A and metabolites fractionated from human bile. Significant differences were observed in Cyclosporine A sensitivity between various cell cultures ranging as high as 100-fold. The liver is the primary site of Cyclosporine A metabolism, which yields a number of hydroxylated and N-dimethylated derivatives that are eventually secreted into the bile. Bile was collected from adult liver transplant patients on Cyclosporine A therapy and following extraction with diethyl ether, separated by high pressure liquid chromatography. Thirteen fractions were tested for their effect on lymphocyte proliferation in concanavalin A activation, mixed lymphocyte cultures and primed lymphocyte test assays. The strongest immunosuppressive effect was found with fraction 8, which contained metabolite M17, which has a single hydroxylation in position 1. Only three other fractions 9, 10, and 13, which contained metabolites M1, M18, and M21, respectively, exhibited immunosuppressive activity, albeit much lower than that of Cyclosporine A. Differences in Cyclosporine A sensitivity among alloreactive T cells followed similar patterns with Cyclosporius A metabolites. Thus, the assessment of the Cyclosporine A effect must consider differences in drug sensitivity of lymphocytes involved in transplant immunity and the generation of metabolites with immunosuppressive activity. © 1988

    An Algorithmic Framework for Labeling Network Maps

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    Drawing network maps automatically comprises two challenging steps, namely laying out the map and placing non-overlapping labels. In this paper we tackle the problem of labeling an already existing network map considering the application of metro maps. We present a flexible and versatile labeling model. Despite its simplicity, we prove that it is NP-complete to label a single line of the network. For a restricted variant of that model, we then introduce an efficient algorithm that optimally labels a single line with respect to a given weighting function. Based on that algorithm, we present a general and sophisticated workflow for multiple metro lines, which is experimentally evaluated on real-world metro maps.Comment: Full version of COCOON 2015 pape

    Experimental investigation of a solar collector integrated with a pulsating heat pipe and a compound parabolic concentrator

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    The paper reports an experimental investigation of a newly proposed solar collector that integrates a closed-end pulsating heat pipe (PHP) and a compound parabolic concentrator (CPC). The PHP is used as an absorber due to its simple structure and high heat transfer capacity. The CPC has a concentration ratio of 3.4 and can be readily manufactured by three-dimensional printing. The CPC can significantly increase the incident solar irradiation intensity to the PHP absorber and also reduce the heat loss due to the decrease in the area of the hot surface. A prototype of the solar collector has been built, consisting of a PHP absorber bent by 4 mm diameter copper tube, CPC arrayed by 10 × 2 CPC units with the collection area of 300 × 427.6 mm2, a hot water tank and a glass cover. HFE7100 was utilized as the working fluid at a filling ratio of 40%. The operating characteristics and thermal efficiency of the solar collector were experimentally studied. The steady and periodic temperature fluctuations of the evaporation and condensation sections of the PHP absorber indicate that the absorber works well with a thermal resistance of about 0.26 °C/W. It is also found that, as the main factor to the the thermal performance of the collector, thermal resistance of the PHP absorber decreases with increasing evaporation temperature. The collector apparently shows start-up, operational and shutdown stages at the starting and ending temperatures of 75 °C. When the direct normal irradiance is 800 W/m2, the instantaneous thermal efficiency of the solar collector can reach up to 50%.The work was financially supported by the National Natural Science Foundation of China (51506004), Beijing Natural Science Foundation (3162009), Scientific Research Project of Beijing Educational Committee (KM201410016001) and Research Fund of Beijing University of Civil Engineering and Architecture
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