3,930 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 “current-driven” 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

    Effects of stitching on delamination of satin weave carbon-epoxy laminates under mode I, mode II and mixed-mode I/II loadings

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    The objective of the present study is to characterize the effect of modified chain stitching on the delamination growth under mixed-mode I/II loading conditions. Delamination toughness under mode I is experimentally determined, for unstitched and stitched laminates, by using untabbed and tabbed double cantilever beam (TDCB) tests. The effect of the reinforcing tabs on mode I toughness is investigated. Stitching improves the energy release rate (ERR) up to 4 times in mode I. Mode II delamination toughness is evaluated in end-notched flexure (ENF) tests. Different geometries of stitched specimens are tested. Crack propagation occurs without any failure of stitching yarns. The final crack length attains the mid-span or it stops before and the specimen breaks in bending. The ERR is initially low and gradually increases with crack length to very high values. The mixedmode delamination behaviour is investigated using a mixed-mode bending (MMB) test. For unstitched specimens, a simple mixed-mode criterion is identified. For stitched specimens, stitching yarns do not break during 25% of mode I ratio tests and the ERR increase is relatively small compared to unstitched values. For 70% and 50% of mode I ratios, failures of yarns are observed during crack propagation and tests are able to capture correctly the effect of the stitching: it clearly improves the ERR for these two mixed modes, as much as threefold

    Experiences of Inpatient Bone Marrow Transplantation Nurses and Providers Using Electronic Symptom Reporting

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    Purpose To investigate the use of electronic patient-reported outcomes (PROs) to assess symptoms and how they can provide opportunities to clinicians to address symptoms in a timely manner to improve clinical care. As part of a larger study to evaluate whether providing standardized symptom reports to the medical team would decrease the time to treatment of reported symptoms in hematopoietic stem-cell transplant recipients, we assessed nurses’ and providers’ perceptions of electronic symptom reporting. Methods Semistructured interviews of RNs, MDs, NPs and PAs were conducted at an academic cancer center in the southeastern United States. Nurses’ and providers’ perceptions of electronic symptom reporting were explored. Interviews were audio-recorded, transcribed, and coded by two investigators to identify major themes. Results Fourteen RNs and seven providers (MDs, PAs, and NPs) participated in the interviews. Three main themes emerged from the interviews: electronic symptom reporting may improve assessment and care, integrating symptom reporting into nurse workflow presents difficulties, and there are barriers for completion of surveys. Conclusion The majority of nurses and providers believed that the inclusion of electronic symptom reporting in bone marrow transplantation inpatient units has the potential to improve care but that barriers to implementation remain

    ASCORE: an up-to-date cardiovascular risk score for hypertensive patients reflecting contemporary clinical practice developed using the (ASCOT-BPLA) trial data.

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    A number of risk scores already exist to predict cardiovascular (CV) events. However, scores developed with data collected some time ago might not accurately predict the CV risk of contemporary hypertensive patients that benefit from more modern treatments and management. Using data from the randomised clinical trial Anglo-Scandinavian Cardiac Outcomes Trial-BPLA, with 15 955 hypertensive patients without previous CV disease receiving contemporary preventive CV management, we developed a new risk score predicting the 5-year risk of a first CV event (CV death, myocardial infarction or stroke). Cox proportional hazard models were used to develop a risk equation from baseline predictors. The final risk model (ASCORE) included age, sex, smoking, diabetes, previous blood pressure (BP) treatment, systolic BP, total cholesterol, high-density lipoprotein-cholesterol, fasting glucose and creatinine baseline variables. A simplified model (ASCORE-S) excluding laboratory variables was also derived. Both models showed very good internal validity. User-friendly integer score tables are reported for both models. Applying the latest Framingham risk score to our data significantly overpredicted the observed 5-year risk of the composite CV outcome. We conclude that risk scores derived using older databases (such as Framingham) may overestimate the CV risk of patients receiving current BP treatments; therefore, 'updated' risk scores are needed for current patients

    Monoclonal antibody levels and protection from COVID-19

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    Multiple monoclonal antibodies have been shown to be effective for both prophylaxis and therapy for SARS-CoV-2 infection. Here we aggregate data from randomized controlled trials assessing the use of monoclonal antibodies (mAb) in preventing symptomatic SARS-CoV-2 infection. We use data on the in vivo concentration of mAb and the associated protection from COVID-19 over time to model the dose-response relationship of mAb for prophylaxis. We estimate that 50% protection from COVID-19 is achieved with a mAb concentration of 96-fold of the in vitro IC50 (95% CI: 32—285). This relationship provides a tool for predicting the prophylactic efficacy of new mAb and against SARS-CoV-2 variants. Finally, we compare the relationship between neutralization titer and protection from COVID-19 after either mAb treatment or vaccination. We find no significant difference between the 50% protective titer for mAb and vaccination, although sample sizes limited the power to detect a difference

    Newsprint coverage of smoking in cars carrying children : a case study of public and scientific opinion driving the policy debate

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    Acknowledgements Date of Acceptance:17/10/2014 Acknowledgements: This project was funded by Cancer Research UK (MC_U130085862) and the Scottish School of Public Health Research. Cancer Research UK and the Scottish School of Public Health Research was not involved in the collection, analysis, and interpretation of data, writing of the manuscript or the decision to submit the manuscript for publication. Shona Hilton, Karen Wood, Josh Bain and Chris Patterson are funded by the UK Medical Research Council as part of the Understandings and Uses of Public Health Research programme (MC_UU_12017/6) at the MRC/CSO Social and Public Health Sciences Unit, University of Glasgow. We thank Alan Pollock who provided assistance with coding.Peer reviewedPublisher PD

    Definitions of massive transfusion in adults with critical bleeding: a systematic review.

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    BACKGROUND: Definitions for massive transfusion (MT) vary widely between studies, contributing to challenges in interpretation of research findings and practice evaluation. In this first systematic review, we aimed to identify all MT definitions used in randomised controlled trials (RCTs) to date to inform the development of consensus definitions for MT. METHODS: We systematically searched the following databases for RCTs from inception until 11 August 2022: MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Cumulative Index to Nursing and Allied Health Literature, and Transfusion Evidence Library. Ongoing trials were sought from CENTRAL, ClinicalTrials.gov, and World Health Organisation International Clinical Trials Registry Platform. To be eligible for inclusion, studies had to fulfil all the following three criteria: (1) be an RCT; (2) include an adult patient population with major bleeding who had received, or were anticipated to receive, an MT in any clinical setting; and (3) specify a definition for MT as an inclusion criterion or outcome measure. RESULTS: Of the 8,458 distinct references identified, 30 trials were included for analysis (19 published, 11 ongoing). Trauma was the most common clinical setting in published trials, while for ongoing trials, it was obstetrics. A total of 15 different definitions of MT were identified across published and ongoing trials, varying greatly in cut-offs for volume transfused and time period. Almost all definitions specified the number of red blood cells (RBCs) within a set time period, with none including plasma, platelets or other haemostatic agents that are part of contemporary transfusion resuscitation. For completed trials, the most commonly used definition was transfusion of ≥ 10 RBC units in 24 h (9/19, all in trauma), while for ongoing trials it was 3-5 RBC units (n = 7), with the timing for transfusion being poorly defined, or in some trials not provided at all (n = 5). CONCLUSIONS: Transfusion of ≥ 10 RBC units within 24 h was the most commonly used definition in published RCTs, while lower RBC volumes are being used in ongoing RCTs. Any consensus definitions should reflect the need to incorporate different blood components/products for MT and agree on whether a 'one-size-fits-all' approach should be used across different clinical settings

    A review of RCTs in four medical journals to assess the use of imputation to overcome missing data in quality of life outcomes

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    Background: Randomised controlled trials (RCTs) are perceived as the gold-standard method for evaluating healthcare interventions, and increasingly include quality of life (QoL) measures. The observed results are susceptible to bias if a substantial proportion of outcome data are missing. The review aimed to determine whether imputation was used to deal with missing QoL outcomes. Methods: A random selection of 285 RCTs published during 2005/6 in the British Medical Journal, Lancet, New England Journal of Medicine and Journal of American Medical Association were identified. Results: QoL outcomes were reported in 61 (21%) trials. Six (10%) reported having no missing data, 20 (33%) reported ≤ 10% missing, eleven (18%) 11%–20% missing, and eleven (18%) reported >20% missing. Missingness was unclear in 13 (21%). Missing data were imputed in 19 (31%) of the 61 trials. Imputation was part of the primary analysis in 13 trials, but a sensitivity analysis in six. Last value carried forward was used in 12 trials and multiple imputation in two. Following imputation, the most common analysis method was analysis of covariance (10 trials). Conclusion: The majority of studies did not impute missing data and carried out a complete-case analysis. For those studies that did impute missing data, researchers tended to prefer simpler methods of imputation, despite more sophisticated methods being available.The Health Services Research Unit is funded by the Chief Scientist Office of the Scottish Government Health Directorate. Shona Fielding is also currently funded by the Chief Scientist Office on a Research Training Fellowship (CZF/1/31)
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