15,904 research outputs found

    Fast physical models for Si LDMOS power transistor characterization

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    A new nonlinear, process-oriented, quasi-two-dimensional (Q2D) model is described for microwave laterally diffused MOS (LDMOS) power transistors. A set of one-dimensional energy transport equations are solved across a two-dimensional cross-section in a ā€œcurrent-drivenā€ form. The model accounts for avalanche breakdown and gate conduction, and accurately predicts DC and microwave characteristics at execution speeds sufficiently fast for circuit simulation applications

    Reflected Light from Sand Grains in the Terrestrial Zone of a Protoplanetary Disk

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    We show that grains have grown to ~mm size (sand sized) or larger in the terrestrial zone (within ~3 AU) of the protoplanetary disk surrounding the 3 Myr old binary star KH 15D. We also argue that the reflected light in the system reaches us by back scattering off the far side of the same ring whose near side causes the obscuration.Comment: 22 pages, 5 figures. To be published in Nature, March 13, 2008. Contains a Supplemen

    Structural performance of hybrid sandwich slabs under shear loading

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    In a hybrid panel with glass fiber reinforced polymer (GFRP) bottom skin and ribs, and deflection hardening cementitious composites (DHCC) top layer, it is very important to provide good shear connection between these various components in order to increase the load carrying capacity of the resulting hybrid slabs and a larger increment of deflection before the occurrence of the structural softening of this panel. The effectiveness of the proposed hybrid sandwich panels strongly depends on the performance of the shear connectors. The efficiency of indented shear connectors in improving the flexural performance of hybrid sandwich panels is here demonstrated. Since the efficiency of indented shear connectors in the hybrid sandwich panels is unknown, efforts are made in this paper in investigating the shear performance of hybrid slabs. A special focus is given on the indented shear connectorā€™s behavior, considering different shear span ratios in ranges of 2.00, 1.39, and 0.77. In this regard, six hybrid sandwich panels were manufactured and experimentally tested under different shear loads. Then, the results are interpreted comprehensively. The results obtained show that the GFRP rib thickness and height, and shear span ratios influence the damage events and the structural performance of the hybrid sandwich panels. Moreover, it was observed that using indented shear connectors in the hybrid slabs, regardless of the shear span ratios, provides high load capacity, high stiffness, and large residual deflection.The study presented in this paper is a part of the research project ā€œRehabGFRP - Rehabilitation of Building Floors with Lightweight High Performance GFRP Sandwich Panelsā€, with reference number of PTDC/ECM/113041/2009

    Prostate Cancer Screening, Detection and Treatment Practices, Among Sub-Saharan African Urologists

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    Introduction: Prostate cancer is reported to be the leading cancer in men in Sub-Saharan Africa (SSA) and the number of prostate cancer deaths is expected to double in the next 20 years. Despite the importance of this public health issue in SSA, there remains relatively limited information about practices related to prostate cancer treatment in this population. Objective: We conducted a survey of 28 urology practices in SSA to evaluate the scope of available screening, detection and treatment. Materials and Methods: Screening was more commonly reported as a part of general medical care in South Africa (SA) compared with East or West (EW) Africa. However, use of digital Rectal Examination (DRE) and Prostate Specific Antigen (PSA) were used at similar rates for screening in all locations. Screening is primarily focused in men over age 50 and those with symptoms. Routine screening was the primary reason for screening use in SA, while symptoms were the primary reason for screening use in EW. Financial and cultural barriers to screening were more commonly reported in EW than SA. Similar detection approaches were used in all regions, with free PSA and PSA velocity being more commonly used in SA than EW. Six core biopsies were more commonly used in EW and 12 core biopsies were more common in SA. Trans urethral ultrasounds and bone scans were more commonly used in SA than EW. Treatment options were similar in all regions, with brachytherapy less likely to be used in EW than SA. Results: The descriptive data suggest that differences in patterns of screening, detection and treatment exist across Africa. Differences by geography may also reflect differences in SES and racial composition of the populations in each region.Key Words: Prostate cancer, Screening and Detection, Practice guidelines, Sub-Saharan Afric

    The Association Between Menā€™s Heath Behaviors and Interest in Workplace Health Promotion

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    Ā© 2019 The Author(s). Background: Predictors of menā€™s health behaviors and interest in workplace health promotion are not well known. The aim of this study was to describe menā€™s interest in workplace health promotion and associated health behaviors. Method: Male employees (N = 781) at six workplaces in British Columbia, Canada, were invited to complete a survey of their health behaviors, demographics, and interest in health promotion prior to implementation of a workplace health program. Findings: A total of 227 male employees (Mage = 43.6 years; SD = 12.1) completed the survey (response rate = 29%). Regarding health behaviors, 62.1% reported 150 weekly minutes of moderate-to-vigorous physical activity (MVPA), 29.3% consumed 5+ servings of fruit/vegetables per day, 56.8% reported 7+ hours sleep/night, 14.4% smoked, and 81.3% consumed alcohol. Men spent 50% of their workday sitting, and higher body mass index (BMI), higher income, and greater hours worked were related to greater hours sitting. Age was inversely related to MVPA. Alcohol consumption was lower among men who were older, had higher income, and worked fewer hours. Most men were interested in being physically active (85%), managing stress (85%), eating healthy (89%), and cancer screening (91%). Higher stage of change for physical activity (Ī² =.20, p =.003) and fruit/vegetable consumption (Ī² =.18, p =.027) were related to interest in these activities. Conclusions/Application to Practice: Occupational health providers should consider worker demographics and could support interventions that target individuals with varying levels of health behaviors given the importance of meeting the needs of often sedentary workers
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