256 research outputs found

    Effect of Reynolds number variation on aerodynamics of a hydrogen-fueled transport concept at Mach 6

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    Two separate tests have been made on the same blended wing-body hydrogen-fueled transport model at a Mach number of about 6 and a range of Reynolds number (based on theoretical body length) of 1.577 to 55.36 X 10 to the 6th power. The results of these tests, made in a conventional hypersonic blowdown tunnel and a hypersonic shock tunnel, are presented through a range of angle of attack from -1 to 8 deg, with an extended study at a constant angle of attack of 3 deg. The model boundary layer flow appeared to be predominately turbulent except for the low Reynolds number shock tunnel tests. Model wall temperatures varied considerably; the blowdown tunnel varied from about 255 F to 340 F, whereas the shock tunnel had a constant 70 F model wall temperature. The experimental normal-force coefficients were essentially independent of Reynolds number. A current theoretical computer program was used to study the effect of Reynolds number. Theoretical predictions of normal-force coefficients were good, particularly at anticipated cruise angles of attack, that is 2 to 5 deg. Axial-force coefficients were generally underestimated for the turbulent skin friction conditions, and pitching-moment coefficients could not be predicted reliably

    Food Security, Depression and Quality of Life in Northern Plains Indians

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    Major health disparities, high levels of poverty and food insecurity exist in many Native American and Alaskan Native (AI/AN) communities. Relatively little research has been done on these issues and possible relationships between them. A research program was designed with the objective of exploring the relationships between these various issues, if any existed, in one sub-group of AI/AN. In the study, the incidence of food insecurity was determined in a convenience sample of Northern Plains Indians (NPI) and correlated with measures of physical and mental health, body composition, quality of life, cultural identification and dietary intakes. Participants were 458 adult attendees at summer powwows and health fairs held at 5 reservations and 3 tribal colleges in North Dakota and western Minnesota. Participants completed various measurements and assessments and pertinent health and demographic data were recorded. Observed incidences of ā€œfood insecurityā€ overall and ā€œvery low food securityā€ in particular (26.4% and 10.4%, respectively) were in sharp contrast to recently reported rates for North Dakota (8.7% and 3.4%) and the U.S. population as a whole (14.7% and 5.6%). In this manuscript, analysis revealed a positive relationship between food insecurity and depression and a negative relationship between food insecurity and quality of life. The findings emphasize the need to address food insecurity when designing research and service programs to address depression in AI/AN populations

    Cardiac Safety Implications of hNav1.5 Blockade and a Framework for Pre-Clinical Evaluation

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    The human cardiac sodium channel (hNav1.5, encoded by the SCN5A gene) is critical for action potential generation and propagation in the heart. Drug-induced sodium channel inhibition decreases the rate of cardiomyocyte depolarization and consequently conduction velocity and can have serious implications for cardiac safety. Genetic mutations in hNav1.5 have also been linked to a number of cardiac diseases. Therefore, off-target hNav1.5 inhibition may be considered a risk marker for a drug candidate. Given the potential safety implications for patients and the costs of late stage drug development, detection, and mitigation of hNav1.5 liabilities early in drug discovery and development becomes important. In this review, we describe a pre-clinical strategy to identify hNav1.5 liabilities that incorporates in vitro, in vivo, and in silico techniques and the application of this information in the integrated risk assessment at different stages of drug discovery and development

    Zinc status and its association with the health of adolescents: a review of studies in India

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    Background: Zinc is important in adolescence because of its role in growth and sexual maturation. Adolescents from developing countries such as India may be at high risk of zinc deficiency because of unwholesome food habits and poor bioavailability of zinc from plant-based diets. Objectives: (1) to study zinc status and its association with profile of other micronutrients, (2) to construct a simple tool in the form of Adolescent Micronutrient Quality Index (AMQI) to assess quality of diets of the girls and (3) to examine the effect of zinc supplement on health of adolescent girls. Methods: Girls (10–16 years) from two secondary schools of Pune, Maharashtra state, in Western India were enrolled in a cross-sectional study (n = 630). Data were collected on dietary intake, cognitive performance, taste acuity, haemoglobin, erythrocyte zinc and plasma levels of zinc, vitamin C, β-carotene and retinol. AMQI was developed using age–sex-specific Indian dietary guidelines and healthy foods and habits described in the recent US dietary guidelines. Zinc-rich recipes were developed considering habitual diets of the girls and vegetarian sources of zinc. An intervention trial (n = 180) was conducted to assess the effect of zinc-rich dietary supplements and ayurvedic zinc (Jasad) supplementation. Results: Prevalence of micronutrient deficiencies was high in these girls. Poor cognitive performance was seen in half of the girls, and salt taste perception was affected in 45%. AMQI was correlated with nutrient intakes and blood micronutrient levels (p < 0.01), indicating the potential of AMQI to measure micronutrient quality of diets of adolescent girls. Results of the intervention trial indicated that supplementation of zinc-rich recipes vis-a-vis ayurvedic Jasad zinc has the potential to improve plasma zinc status, cognitive performance and taste acuity in adolescent girls. Conclusion: Review of the studies on Indian adolescent girls demonstrates the necessity of adopting zinc and micronutrient-rich diets for positive health building in adolescents

    Effects of exenatide and open-label SGLT2 inhibitor treatment, given in parallel or sequentially, on mortality and cardiovascular and renal outcomes in type 2 diabetes:insights from the EXSCEL trial

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    Background Sodium-glucose cotransporter-2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1 RA) improve cardiovascular and renal outcomes in patients with type 2 diabetes through distinct mechanisms. However, evidence on clinical outcomes in patients treated with both GLP-1 RA and SGLT2i is lacking. We aim to provide insight into the effects of open-label SGLT2i use in parallel with or shortly after once-weekly GLP-1 RA exenatide (EQW) on cardiorenal outcomes. Methods In the EXSCEL cardiovascular outcomes trial EQW arm, SGLT2i drop-in occurred in 8.7% of participants. These EQW+SGLT2i users were propensity-matched to: (1) placebo-arm participants not taking SGLT2i (n = 572 per group); and to (2) EQW-arm participants not taking SGLT2i (n = 575), based on their last measured characteristics before SGLT2i initiation, and equivalent study visit in comparator groups. Time-to-first major adverse cardiovascular event (MACE) and all-cause mortality (ACM) were compared using Cox regression analyses. eGFR slopes were quantified using mixed model repeated measurement analyses. Results In adjusted analyses, the risk for MACE with combination EQW+SGLT2i use was numerically lower compared with both placebo (adjusted hazard ratio 0.68, 95% CI 0.39-1.17) and EQW alone (0.85, 0.48-1.49). Risk of ACM was nominally significantly reduced compared with placebo (0.38, 0.16-0.90) and compared with EQW (0.41, 0.17-0.95). Combination EQW+SGLT2i use also nominally significantly improved estimated eGFR slope compared with placebo (+ 1.94, 95% CI 0.94-2.94 mL/min/1.73 m(2)/year) and EQW alone (+ 2.38, 1.40-3.35 mL/min/1.73 m(2)/year). Conclusions This post hoc analysis supports the hypothesis that combinatorial EQW and SGLT2i therapy may provide benefit on cardiovascular outcomes and mortality. Trial registration Clinicaltrials.gov, Identifying number: NCT01144338, Date of registration: June 15, 2010

    Estimating the predictability of an oceanic time series using linear and nonlinear methods

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    Author Posting. Ā© American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C08002, doi:10.1029/2003JC002148.This study establishes a series of tests to examine the relative utility of nonlinear time series analysis for oceanic data. The performance of linear autoregressive models and nonlinear delay coordinate embedding methods are compared for three numerical and two observational data sets. The two observational data sets are (1) an hourly near-bottom pressure time series from the South Atlantic Bight and (2) an hourly current-meter time series from the Middle Atlantic Bight (MAB). The nonlinear methods give significantly better predictions than the linear methods when the underlying dynamics have low dimensionality. When the dimensionality is high, the utility of nonlinear methods is limited by the length and quality of the time series. On the application side we mainly focus on the MAB data set. We find that the slope velocities are much less predictable than shelf velocities. Predictability on the slope after several hours is no better than the statistical mean. On the other hand, significant predictability of shelf velocities can be obtained for up to at least 12 hours.This research was supported by Office of Naval Research grants N00014-01-1-0260, N00014-92-J-1481, and N10014-99-1-0258

    Zinc intake, status and indices of cognitive function in adults and children: a systematic review and meta-analysis

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    In developing countries, deficiencies of micronutrients are thought to have a major impact on child development; however, a consensus on the specific relationship between dietary zinc intake and cognitive function remains elusive. The aim of this systematic review was to examine the relationship between zinc intake, status and indices of cognitive function in children and adults. A systematic literature search was conducted using EMBASE, MEDLINE and Cochrane Library databases from inception to March 2014. Included studies were those that supplied zinc as supplements or measured dietary zinc intake. A meta-analysis of the extracted data was performed where sufficient data were available. Of all of the potentially relevant papers, 18 studies met the inclusion criteria, 12 of which were randomised controlled trials (RCTs; 11 in children and 1 in adults) and 6 were observational studies (2 in children and 4 in adults). Nine of the 18 studies reported a positive association between zinc intake or status with one or more measure of cognitive function. Meta-analysis of data from the adultā€™s studies was not possible because of limited number of studies. A meta-analysis of data from the six RCTs conducted in children revealed that there was no significant overall effect of zinc intake on any indices of cognitive function: intelligence, standard mean difference of <0.001 (95% confidence interval (CI) ā€“0.12, 0.13) P=0.95; executive function, standard mean difference of 0.08 (95% CI, ā€“0.06, 022) P=0.26; and motor skills standard mean difference of 0.11 (95% CI ā€“0.17, 0.39) P=0.43. Heterogeneity in the study designs was a major limitation, hence only a small number (n=6) of studies could be included in the meta-analyses. Meta-analysis failed to show a significant effect of zinc supplementation on cognitive functioning in children though, taken as a whole, there were some small indicators of improvement on aspects of executive function and motor development following supplementation but high-quality RCTs are necessary to investigate this further
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