Evaluation of Rhenium Joining Methods

Coupons of rhenium-to-Cl03 flat plate joints, formed by explosive and diffusion bonding, were evaluated in a series of shear tests. Shear testing was conducted on as-received, thermally-cycled (100 cycles, from 21 to 1100 C), and thermally-aged (3 and 6 hrs at 1100 C) joint coupons. Shear tests were also conducted on joint coupons with rhenium and/or Cl03 electron beam welded tabs to simulate the joint's incorporation into a structure. Ultimate shear strength was used as a figure of merit to assess the effects of the thermal treatment and the electron beam welding of tabs on the joint coupons. All of the coupons survived thermal testing intact and without any visible degradation. Two different lots of as-received, explosively-bonded joint coupons had ultimate shear strengths of 281 and 310 MPa and 162 and 223 MPa, respectively. As-received, diffusion-bonded coupons had ultimate shear strengths of 199 and 348 MPa. For the most part, the thermally-treated and rhenium weld tab coupons had shear strengths slightly reduced or within the range of the as-received values. Coupons with Cl03 weld tabs experienced a significant reduction in shear strength. The degradation of strength appeared to be the result of a poor heat sink provided during the electron beam welding. The Cl03 base material could not dissipate heat as effectively as rhenium, leading to the formation of a brittle rhenium-niobium intermetallic

Relationships between intensity, duration, cumulative dose, and timing of smoking with age at menopause: A pooled analysis of individual data from 17 observational studies

BACKGROUND: Cigarette smoking is associated with earlier menopause, but the impact of being a former smoker and any dose-response relationships on the degree of smoking and age at menopause have been less clear. If the toxic impact of cigarette smoking on ovarian function is irreversible, we hypothesized that even former smokers might experience earlier menopause, and variations in intensity, duration, cumulative dose, and age at start/quit of smoking might have varying impacts on the risk of experiencing earlier menopause. METHODS AND FINDINGS: A total of 207,231 and 27,580 postmenopausal women were included in the cross-sectional and prospective analyses, respectively. They were from 17 studies in 7 countries (Australia, Denmark, France, Japan, Sweden, United Kingdom, United States) that contributed data to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE). Information on smoking status, cigarettes smoked per day (intensity), smoking duration, pack-years (cumulative dose), age started, and years since quitting smoking was collected at baseline. We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRRs) and 95% confidence intervals (CIs) for the associations between each smoking measure and categorised age at menopause ( \u3c 40 (premature), 40-44 (early), 45-49, 50-51 (reference), and \u3e /=52 years). The association with current and former smokers was analysed separately. Sensitivity analyses and two-step meta-analyses were also conducted to test the results. The Bayesian information criterion (BIC) was used to compare the fit of the models of smoking measures. Overall, 1.9% and 7.3% of women experienced premature and early menopause, respectively. Compared with never smokers, current smokers had around twice the risk of experiencing premature (RRR 2.05; 95% CI 1.73-2.44) (p \u3c 0.001) and early menopause (1.80; 1.66-1.95) (p \u3c 0.001). The corresponding RRRs in former smokers were attenuated to 1.13 (1.04-1.23; p = 0.006) and 1.15 (1.05-1.27; p = 0.005). In both current and former smokers, dose-response relationships were observed, i.e., higher intensity, longer duration, higher cumulative dose, earlier age at start smoking, and shorter time since quitting smoking were significantly associated with higher risk of premature and early menopause, as well as earlier menopause at 45-49 years. Duration of smoking was a strong predictor of age at natural menopause. Among current smokers with duration of 15-20 years, the risk was markedly higher for premature (15.58; 11.29-19.86; p \u3c 0.001) and early (6.55; 5.04-8.52; p \u3c 0.001) menopause. Also, current smokers with 11-15 pack-years had over 4-fold (4.35; 2.78-5.92; p \u3c 0.001) and 3-fold (3.01; 2.15-4.21; p \u3c 0.001) risk of premature and early menopause, respectively. Smokers who had quit smoking for more than 10 years had similar risk as never smokers (1.04; 0.98-1.10; p = 0.176). A limitation of the study is the measurement errors that may have arisen due to recall bias. CONCLUSIONS: The probability of earlier menopause is positively associated with intensity, duration, cumulative dose, and earlier initiation of smoking. Smoking duration is a much stronger predictor of premature and early menopause than others. Our findings highlight the clear benefits for women of early smoking cessation to lower their excess risk of earlier menopause

Adolescent Self-Consent for Biomedical HIV Prevention Research: Implications for Institutional Review Board Approval and Implementation

Purpose The Adolescent Medicine Trials Network Protocol 113 (ATN113) is an open-label, multisite demonstration project and Phase II safety study of human immunodeficiency virus (HIV) preexposure prophylaxis with 15- to 17-year-old young men who have sex with men that requires adolescent consent for participation. The purpose of this study was to examine factors related to the process by which Institutional Review Boards (IRBs) and researchers made decisions regarding whether to approve and implement ATN113 so as to inform future biomedical HIV prevention research with high-risk adolescent populations. Methods Participants included 17 researchers at 13 sites in 12 states considering ATN113 implementation. Qualitative descriptive methods were used. Data sources included interviews and documents generated during the initiation process. Results A common process for initiating ATN113 emerged, and informants described how they identified and addressed practical, ethical, and legal challenges that arose. Informants described the process as responding to the protocol, preparing for IRB submission, abstaining from or proceeding with submission, responding to IRB concerns, and reacting to the outcomes. A complex array of factors impacting approval and implementation were identified, and ATN113 was ultimately implemented in seven of 13 sites. Informants also reflected on lessons learned that may help inform future biomedical HIV prevention research with high-risk adolescent populations. Conclusions The results illustrate factors for consideration in determining whether to implement such trials, demonstrate that such protocols have the potential to be approved, and highlight a need for clearer standards regarding biomedical HIV prevention research with high-risk adolescent populations

A Laboratory Model of a Hydrogen/Oxygen Engine for Combustion and Nozzle Studies

A small laboratory diagnostic thruster was developed to augment present low thrust chemical rocket optical and heat flux diagnostics at the NASA Lewis Research Center. The objective of this work was to evaluate approaches for the use of temperature and pressure sensors for the investigation of low thrust rocket flow fields. The nominal engine thrust was 110 N. Tests were performed at chamber pressures of about 255 kPa, 370 kPa, and 500 kPa with oxidizer to fuel mixture ratios between 4.0 and 8.0. Two gaseous hydrogen/gaseous oxygen injector designs were tested with 60 percent and 75 percent fuel film cooling. The thruster and instrumentation designs were proven to be effective via hot fire testing. The thruster diagnostics provided inner wall temperature and static pressure measurements which were compared to the thruster global performance data. For several operating conditions, the performance data exhibited unexpected trends which were correlated with changes in the axial wall temperature distribution. Azimuthal temperature distributions were found to be a function of operating conditions and hardware configuration. The static pressure profiles showed that no severe pressure gradients were present in the rocket. The results indicated that small differences in injector design can result in dramatically different thruster performance and wall temperature behavior, but that these injector effects may be overshadowed by operating at a high fuel film cooling rate

Minors' and Young Adults' Experiences of the Research Consent Process in a Phase II Safety Study of Pre-exposure Prophylaxis for HIV

PURPOSE: There is a persistent HIV epidemic among sexual and gender minority adolescents in the U.S. Oral pre-exposure prophylaxis (PrEP) is an efficacious prevention strategy, but not yet approved for minors. Minors' access to biomedical HIV prevention technologies is impeded by the ethical and legal complexities of consent to research participation. We explore autonomous consent and study experiences among minor and adult participants in Project PrEPare, a Phase II safety study of PrEP for HIV prevention. METHODS: Data for this mixed-methods descriptive study were collected via self-administered web-survey and in-depth telephone interviews in early 2016. Eligible participants were previously enrolled in Project PrEPare. We attempted to contact 191 participants; 74 were reached and expressed interest in participating and 58 enrolled. RESULTS: Participants nearly universally felt well informed, understood the study, and freely volunteered with the clear understanding they could withdraw any time. All felt supported by study staff, but a small minority wished for more support during enrollment. Minors were more likely than adults to indicate a wish for more support in decision-making, and adults expressed higher satisfaction with their decision compared to minors. There was no association between elements of consent and Project PrEPare study outcomes. CONCLUSIONS: Participants had an overwhelmingly positive experience in a Phase II safety study of PrEP for HIV prevention. Some minors wished for more support during the decision-making process, but none consulted their parents about the decision. Our results support the inclusion of decisional supports in consent processes for adolescents, while also protecting their privacy

An exploration of the role of religion/spirituality in the promotion of physicians\u27 wellbeing in Emergency Medicine

BACKGROUND: Burnout is highly prevalent among Emergency Medicine (EM) physicians and has significant impact on quality of care and workforce retention. The objective of this study was to determine whether higher religion/spirituality (R/S) is associated with a lower prevalence of burnout among EM physicians (primary outcome). A history of malpractice lawsuits and maladaptive behaviors were the secondary outcomes. METHODS: This was a cross-sectional, survey-based study conducted among a random sample of physicians from the Massachusetts College of Emergency Physicians mailing list. Burnout was measured using a validated 2-item version of the Maslach Burnout Inventory. Maladaptive behaviors (smoking, drinking, and substance use) and medical malpractice were self-reported. R/S measures included organized religiosity, religious affiliation, private R/S practice, self-rated spirituality, religious rest, and religious commitment. Logistic regression was used to model study outcomes as a function of R/S predictors. RESULTS: Of 422 EM physicians who received the invitation to participate, 138 completed the survey (32.7%). The prevalence of burnout was 27%. No significant associations were observed between burnout and R/S indicators. Maladaptive behaviors (adjusted OR = 0.42, CI: 0.19 to 0.96; p = 0.039) and history of medical malpractice (adjusted OR = 0.32; CI: 0.11 to 0.93; p = 0.037) were less likely among physicians reporting to be more involved in organized religious activity and to observe a day of rest for religious reasons, respectively. CONCLUSION: This study provides preliminary evidence for a possible protective association of certain dimensions of R/S on maladaptive behaviors and medical malpractice among EM physicians

Geriatric Conditions Are Associated With Decreased Anticoagulation Use in Long-Term Care Residents With Atrial Fibrillation

Background Anticoagulation is the mainstay for stroke prevention in patients with atrial fibrillation, but concerns about bleeding inhibit its use in residents of long-term care facilities. Risk-profiling algorithms using comorbid disease information (eg, CHADS2 and ATRIA [Anticoagulation and Risk Factors in Atrial Fibrillation]) have been available for years. In the long-term care setting, however, providers and residents may place more value on geriatric conditions such as mobility impairment, activities of daily living dependency, cognitive impairment, low body mass index, weight loss, and fall history. Methods and Results Using a retrospective cohort design, we measured the association between geriatric conditions and anticoagulation use and type. After merging nursing home assessments containing information about geriatric conditions (Minimum Data Set 2015) with Medicare Part A 2014 to 2015 claims and prescription claims (Medicare Part D) 2015 to 2016, we identified 228 741 residents with atrial fibrillation and elevated stroke risk (CHA2DS2-VASc score \u3e /=2) for our main analysis. Recent fall, activities of daily living dependency, moderate and severe cognitive impairment, low body mass index, and unintentional weight loss were all associated with lower anticoagulation use even after adjustment for multiple predictors of stroke and bleeding (odds ratios ranging from 0.51 to 0.91). Residents with recent fall, low body mass index, and unintentional weight loss were more likely to be using a direct oral anticoagulant, although the magnitude of this effect was smaller. Conclusions Geriatric conditions were associated with lower anticoagulation use. Preventing stroke in these residents with potential for further physical and cognitive impairment would appear to be of paramount significance, although the net benefit of anticoagulation in these individuals warrants further research