45 research outputs found

    Liquid Oxygen/Liquid Methane Propulsion and Cryogenic Advanced Development

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    Exploration Systems Architecture Study conducted by NASA in 2005 identified the liquid oxygen (LOx)/liquid methane (LCH4) propellant combination as a prime candidate for the Crew Exploration Vehicle Service Module propulsion and for later use for ascent stage propulsion of the lunar lander. Both the Crew Exploration Vehicle and Lunar Lander were part the Constellation architecture, which had the objective to provide global sustained lunar human exploration capability. From late 2005 through the end of 2010, NASA and industry matured advanced development designs for many components that could be employed in relatively high thrust, high delta velocity, pressure fed propulsion systems for these two applications. The major investments were in main engines, reaction control engines, and the devices needed for cryogenic fluid management such as screens, propellant management devices, thermodynamic vents, and mass gauges. Engine and thruster developments also included advanced high reliability low mass igniters. Extensive tests were successfully conducted for all of these elements. For the thrusters and engines, testing included sea level and altitude conditions. This advanced development provides a mature technology base for future liquid oxygen/liquid methane pressure fed space propulsion systems. This paper documents the design and test efforts along with resulting hardware and test results

    Correlates and outcomes of posttransplant smoking in solid organ transplant recipients : a systematic literature review and meta-analysis

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    Despite smoking being an absolute or relative contraindication for transplantation, about 11% to 40% of all patients continue or resume smoking posttransplant. This systematic review with meta-analysis investigated the correlates and outcomes associated with smoking after solid organ transplantation.; We searched PubMed, EMBASE, CINAHL, and PsycINFO from inception until January 2016, using state-of-the art methodology. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were computed for correlates/outcomes investigated 5 times or more.; Seventy-three studies (43 in kidney, 17 in heart, 12 in liver, 1 in lung transplantation) investigated 95 correlates and 24 outcomes, of which 6 correlates and 4 outcomes could be included in the meta-analysis. The odds of smoking posttransplant were 1.33 times higher in men (95% CI, 1.12-1.57). Older individuals were significantly less likely to smoke (OR, 0.48; 95% CI, 0.38-0.62), as were patients with a higher body mass index (OR, 0.68; 95% CI, 0.52-0.89). Hypertension (OR, 1.16; 95% CI, 0.77-1.75), diabetes mellitus (OR, 0.52; 95% CI, 0.15-1.78), and having a history of cardiovascular disease (OR, 0.92; 95% CI, 0.77-1.09) were not significant correlates. Posttransplant smokers had higher odds of newly developed posttransplant cardiovascular disease (OR, 1.41; 95% CI, 1.02-1.95), nonskin malignancies (OR, 2.58; 95% CI, 1.26-5.29), a shorter patient survival time (OR, 0.59; 95% CI, 0.44-0.79), and higher odds of mortality (OR, 1.74; 95% CI, 1.21-2.48).; Posttransplant smoking is associated with poor outcomes. Our results might help clinicians to understand which patients are more likely to smoke posttransplant, guide interventional approaches, and provide recommendations for future research

    HIV infection and sexual risk among men who have sex with men and women (MSMW): A systematic review and meta-analysis

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    Objectives: To estimate the number of men who have sex with men and women who are HIV-positive in the United States, and to compare HIV prevalence rates between men who have sex with men and women, men who have sex with men only, and men who have sex with women exclusively. Methods: Following PRISMA guidelines, we conducted a systematic review and meta-analysis of reports referencing HIV prevalence and men who have sex with men and women. We searched PubMed and Ovid PsycINFO for peer-reviewed, U.S.-based articles reporting on HIV prevalence among men who have sex with men and women. We conducted event rate, effect size, moderation and sensitivity analyses. Results: We estimate that 1.0% of U.S. males are bisexually-behaving, and that 121,800 bisexually-behaving men are HIV-positive. Men who have sex with men and women are less than half as likely to be HIV-positive as men who have sex with men only (16.9% vs. 33.3%; OR = 0.41, 95% CI: 0.31, 0.54), but more than five times as likely to be HIV-positive as men who have sex with women exclusively (18.3% vs. 3.5%; OR = 5.71, 95% CI: 3.47, 9.39). They are less likely to engage in unprotected receptive anal intercourse than men who have sex with men only (15.9% vs. 35.0%; OR = 0.36, 95% CI: 0.28, 0.46). Men who have sex with men and women in samples with high racial/ethnic minority proportions had significantly higher HIV prevalence than their counterparts in low racial/ethnic minority samples. Conclusions: This represents the first meta-analysis of HIV prevalence in the U.S. between men who have sex with men and women and men who have sex with men only. Data collection, research, and HIV prevention and care delivery specifically tailored to men who have sex with men and women are necessary to better quantify and ameliorate this population's HIV burden. © 2014 Friedman et al

    Open Access Journals: the Pros and Cons

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    Presentation given at University of Pittsburgh School of Nursing Center for Research and Evaluation Research Methodology Series

    Risk factors for falls in adult cancer survivors: An integrative review

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    Purpose The aim of the study was to identify risk factors for falls among cancer survivors. Design Integrative literature review. Methods We searched PubMed, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and PEDro for studies investigating fall risk in cancer. Reports of randomized controlled trials, descriptive studies (quantitative and qualitative), and theoretical papers meeting predetermined criteria were included. Quality ratings of included studies were done, and data were extracted and compiled by two independent reviewers. Findings Twenty-nine articles met inclusion criteria. Literature quality was moderate (median quality score: 1.67 out of 3 possible points). Heterogeneity of statistics and reporting methods precluded calculation of summary effect sizes, but physical function, cognitive function, balance/gait, and certain medication types appear to increase fall risk. Conclusions and Clinical Relevance Modifiable risk factors, such as those identified in this review, represent tangible intervention targets for rehabilitation professionals for decreasing the risk of falls among cancer survivors

    Risk Factors for Falls in Adult Cancer Survivors: An Integrative Review

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    Purpose The aim of the study was to identify risk factors for falls among cancer survivors. Design Integrative literature review. Methods We searched PubMed, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and PEDro for studies investigating fall risk in cancer. Reports of randomized controlled trials, descriptive studies (quantitative and qualitative), and theoretical papers meeting predetermined criteria were included. Quality ratings of included studies were done, and data were extracted and compiled by two independent reviewers. Findings Twenty-nine articles met inclusion criteria. Literature quality was moderate (median quality score: 1.67 out of 3 possible points). Heterogeneity of statistics and reporting methods precluded calculation of summary effect sizes, but physical function, cognitive function, balance/gait, and certain medication types appear to increase fall risk. Conclusions and Clinical Relevance Modifiable risk factors, such as those identified in this review, represent tangible intervention targets for rehabilitation professionals for decreasing the risk of falls among cancer survivors

    Vitamin D deficiency is widespread in cancer patients and correlates with advanced stage disease: a community oncology experience.

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    The purpose of this study was to correlate serum vitamin D levels with potential clinical variables and to determine the extent of vitamin D deficiency in a large, outpatient oncology practice. One hundred ninety-five consecutive patients referred for consultation at a community radiation oncology center from October 8, 2008 to March 17, 2010 had vitamin D levels ordered. Patients who were deficient in vitamin D were treated with replacement therapy. Demographic and medical data were collected prospectively and subsequently analyzed. Pretreatment baseline patient and tumor characteristics were evaluated with respect to vitamin D concentrations. One hundred and sixty patients were analyzed. A total of 74% of patients had 25-hydroxyvitamin D concentrations considered either deficient (/mL) or suboptimal (20-30 ng/mL). Replacement therapy raised serum vitamin D levels by an average of 15 ng/mL (95% CI = 11-18, P \u3c 0.01). Lower than median serum vitamin D levels were associated with stage III disease in univariate analysis [OR = 2.6 (95% CI = 1.1-6.2), p = 0.04] as well as multivariate analysis adjusted for age, sex, body mass index, and season of draw [OR = 3.3 (95% CI = 1.1-9.7), P = 0.03]. Three-quarters of patients in our series had suboptimal or deficient circulating concentrations of 25-hydroxyvitamin D. Low serum vitamin D levels, independent of age, sex, and body mass index, predicted advanced stage disease
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