312 research outputs found

    The Effects of the Flyer Plate\u27s Radius of Curvature on the Performance of an Explosively Formed Projectile

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    An explosively formed projectile (EFP) is known for its ability to penetrate vehicle armor effectively. Understanding how an EFP’s physical parameters affect its performance is crucial to development of armor capable of defeating such devices. The present study uses two flyer plate radii of curvature to identify the experimental effects of the flyer plate’s radius of curvature on the measured projectile velocity, depth of penetration, and projectile shape. The Gurney equation is an algebraic relationship for estimating the velocity imparted to a metal plate in contact with detonating explosives. The authors of this research used a form of the Gurney equation to calculate the theoretical flyer plate velocity. Two EFP designs that have different flyer plate radii of curvature, but the same physical parameters and the same flyer-weight to charge-weight ratio should theoretically have the same velocity. Tests indicated that the flyer plate’s radius of curvature does not affect the projectile’s velocity and that a flat flyer plate negatively affects projectile penetration and formation

    High Efficiency InP Solar Cells from Low Toxicity Tertiarybutylphosphine

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    Large scale manufacture of phosphide based semiconductor devices by organo-metallic vapor phase epitaxy (OMVPE) typically requires the use of highly toxic phosphine. Advancements in phosphine substitutes have identified tertiarybutylphosphine (TBP) as an excellent precursor for OMVPE of InP. High quality undoped and doped InP films were grown using TBP and trimethylindium. Impurity doped InP films were achieved utilizing diethylzinc and silane for p and n type respectively. 16 percent efficient solar cells under air mass zero, one sun intensity were demonstrated with Voc of 871 mV and fill factor of 82.6 percent. It was shown that TBP could replace phosphine, without adversely affecting device quality, in OMVPE deposition of InP thus significantly reducing toxic gas exposure risk

    InGaAs PV Device Development for TPV Power Systems

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    Indium gallium arsenide (InGaAs) photovoltaic devices have been fabricated with bandgaps ranging from 0.75 eV to 0.60 eV on Indium Phosphide (InP) substrates. Reported efficiencies have been as high as 11.2 percent (AMO) for the lattice matched 0.75 eV devices. The 0.75 eV cell demonstrated 14.8 percent efficiency under a 1500 K blackbody with a projected efficiency of 29.3 percent. The lattice mismatched devices (0.66 and 0.60 eV) demonstrated measured efficiencies of 8 percent and 6 percent respectively under similar conditions. Low long wavelength response and high dark currents are responsible for the poor performance of the mismatched devices. Temperature coefficients have been measured and are presented for all of the bandgaps tested

    Sexual dimorphism in immune response genes as a function of puberty

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    BACKGROUND: Autoimmune diseases are more prevalent in females than in males, whereas males have higher mortality associated with infectious diseases. To increase our understanding of this sexual dimorphism in the immune system, we sought to identify and characterize inherent differences in immune response programs in the spleens of male and female mice before, during and after puberty. RESULTS: After the onset of puberty, female mice showed a higher expression of adaptive immune response genes, while males had a higher expression of innate immune genes. This result suggested a requirement for sex hormones. Using in vivo and in vitro assays in normal and mutant mouse strains, we found that reverse signaling through FasL was directly influenced by estrogen, with downstream consequences of increased CD8(+ )T cell-derived B cell help (via cytokines) and enhanced immunoglobulin production. CONCLUSION: These results demonstrate that sexual dimorphism in innate and adaptive immune genes is dependent on puberty. This study also revealed that estrogen influences immunoglobulin levels in post-pubertal female mice via the Fas-FasL pathway

    InGaAs PV device development for TPV power systems

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    Indium gallium arsenide (InGaAs) photovoltaic devices have been fabricated with bandgaps ranging from 0.75 eV to 0.60 on Indium phosphide (InP) substrates. Reported efficiencies have been as high as 11.2 percent (AMO) for the lattice matched 0.75 eV devices. The 0.75 eV cell demonstrated 14.8 percent efficiency under a 1500 K blackbody with a projected efficiency of 29.3 percent. The lattice mismatched devices (0.66 and 0.60 eV) demonstrated measured efficiencies of 8 percent and 6 percent respectively under similar conditions. Low long wavelength response and high rack currents are responsible for the poor performance of the mismatched devices. Temperature coefficients have been measured and are presented for all of the bandgaps tested

    Immediate Blood Draw for CD4+ Cell Count Is Associated with Linkage to Care in Durban, South Africa: Findings from Pathways to Engagement in HIV Care

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    Background Timely linkage to care by newly-diagnosed HIV+ individuals remains a significant challenge to achieving UNAIDS 90-90-90 goals. Current World Health Organization (WHO) guidelines recommend initiating anti-retroviral treatment (ART) regardless of CD4+ count, with priority given to those with CD4+ <350 cells/μl. We evaluated the impact of not having a day-of-diagnosis CD4+ count blood draw, as recommended by South African guidelines, on time to linkage, using data from a prospective cohort study. Methods Individuals (N = 2773) were interviewed prior to HIV counseling and testing at three public sector primary care clinics in the greater Durban area; 785 were newly-diagnosed and eligible for the cohort study; 459 (58.5%) joined and were followed for eight months with three structured assessments. Linkage to care, defined as returning to clinic for CD4+ count results, and day-of-diagnosis blood draw were self-reported. Results Overall, 72.5% did not have a day-of-diagnosis CD4+ count blood draw, and 19.2% of these never returned. Compared with a day-of-diagnosis blood draw, the adjusted hazard ratio of linkage (AHRlinkage) associated with not having day-of-diagnosis blood draw was 0.66 (95%CI: 0.51, 0.85). By 4 months, 54.8% of those without day-of-diagnosis blood draw vs. 75.2% with one were linked to care (chi-squared p = 0.004). Of those who deferred blood draw, 48.3% cited clinic-related and 51.7% cited personal reasons. AHRlinkage was 0.60 (95%CI: 0.44, 0.82) for clinic-related and 0.53 (95%CI: 0.38, 0.75) for personal reasons relative to having day-of-diagnosis blood draw. Conclusions Newly-diagnosed HIV+ individuals who did not undergo CD4+ count blood draw on the day they were diagnosed—regardless of the reason for deferring—had delayed linkage to care relative to those with same-day blood draw. To enhance prompt linkage to care even when test and treat protocols are implemented, all diagnostic testing required before ART initiation should be performed on the same day as HIV testing/diagnosis. This may require modifying clinic procedures to enable overnight blood storage if same-day draws cannot be performed, and providing additional counseling to encourage newly-diagnosed individuals to complete day-of-diagnosis testing. Tracking HIV+ individuals via clinic registries should commence immediately from diagnosis to reduce these early losses to care

    Data rescue: An assessment framework for legacy research collections

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    Widespread investments in the reproducibility and reuse of scientific data have spurred an increasing recognition of the potential value of data biding in unpublished records and collections of legacy research materials, such as scientists’ papers, historical publications, and working files. Recovering usable scientific data from legacy collections constitutes one kind of data rescue: the application of selected data curation processes to data at imminent risk of loss. Given the growing interest in data-intensive science and growing movement toward computationally amenable collections in memory institutions, the National Agricultural Library and other curation institutions need systematic approaches to processing legacy collections with the specific goal of retrieving reusable or historically valuable scientific data. This white paper reports on research conducted under the auspices of the Digital Curation Fellows Program, a collaborative research initiative of the United States Department of Agriculture’s National Agricultural Library and the University of Maryland College of Information Studies. We offer a framework for assessing collections of scientific records for the purpose of data rescue, developed through research on three case studies of agricultural research collections. This framework aims to guide data rescue initiatives at the National Agricultural Library and other agricultural research centers, and to provide conceptual and practical framing for emerging conversations around data rescue in the agricultural research community and across disciplines.This white paper is the product of research conducted under a Non-Assistance Cooperative Agreement #58-8260-6-003 between the University of Maryland and the United States Department of Agriculture (USDA), Agricultural Research Service (ARS), National Agricultural Library with funding provided by the USDA, ARS, Office of National Programs

    Increased SIRT3 combined with PARP inhibition rescues motor function of SBMA mice.

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    Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease with substantial mitochondrial and metabolic dysfunctions. SBMA is caused by polyglutamine (polyQ) expansion in the androgen receptor (AR). Activating or increasing the NAD+-dependent deacetylase, SIRT3, reduced oxidative stress and death of cells modeling SBMA. However, increasing diminished SIRT3 in AR100Q mice failed to reduce acetylation of the SIRT3 target/antioxidant, SOD2, and had no effect on increased total acetylated peptides in quadriceps. Yet, overexpressing SIRT3 resulted in a trend of motor recovery, and corrected TCA cycle activity by decreasing acetylation of SIRT3 target proteins. We sought to boost blunted SIRT3 activity by replenishing diminished NAD+ with PARP inhibition. Although NAD+ was not affected, overexpressing SIRT3 with PARP inhibition fully restored hexokinase activity, correcting the glycolytic pathway in AR100Q quadriceps, and rescued motor endurance of SBMA mice. These data demonstrate that targeting metabolic anomalies can restore motor function downstream of polyQ-expanded AR

    Temporal spatial and metabolic measures of walking in highly functional individuals with lower limb amputations

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    OBJECTIVE: The aim of this descriptive exploratory study is to record the temporal spatial parameters and metabolic energy expenditure during walking of individuals with amputation, walking with advanced prostheses and following completion of comprehensive rehabilitation, to able-bodied controls. DESIGN: Cross-sectional SETTING: Multi-disciplinary comprehensive rehabilitation centre PARTICIPANTS: Thirty severely injured United Kingdom military personnel with amputation and subsequent completion of their rehabilitation programme (10 unilateral trans-tibial, 10 unilateral trans-femoral, and 10 bilateral trans-femoral) were compared to (and of similar age, height and mass (p &lt; 0.537) as) 10 able-bodied controls. INTERVENTIONS: Not applicable Main Outcomes and Measures: Temporal spatial and metabolic energy expenditure data were captured during walking on level ground at self-selected speed. RESULTS: The individuals with amputation were all male, with a mean age 29 years (SD = 4) and mean New Injury Severity Score of 31 (SD = 16). Walking speed, stride length, step length and cadence of individuals with a unilateral trans-tibial or trans-femoral amputation was comparable to controls, and only for individuals with a bilateral trans-femoral amputation was walking speed significantly slower (1·12m/s, p = 0.025) and cadence reduced (96 steps/min, p = 0.026). Oxygen cost for individuals with a unilateral trans-tibial amputation (0·15 ml/kg/m) was the same as for controls (0·15 ml/kg/m), and significantly increased by 20% (0·18ml/kg/m, p = 0.023) for unilateral trans-femoral and by 60% (0·24 ml/kg/m, p &lt; 0.001) for bilateral trans-femoral individuals with amputation. CONCLUSION: The scientific literature reports a wide range of gait and metabolic energy expenditure across individuals with amputation. The results of this study indicate that the individuals with amputation have a gait pattern which is highly functional and efficient. This is comparable to a small number of studies reporting similar outcomes for individuals with a unilateral trans-tibial amputation, but the results from this study are better than those on individuals with trans-femoral amputations reported elsewhere, despite comparison with populations wearing similar prosthetic componentry. Those studies that do report similar outcomes have included individuals who have been provided with a comprehensive rehabilitation programme. This suggests that such a programme may be as important as, or even more important than, prosthetic component selection in improving metabolic energy expenditure. The data are made available as a benchmark for what is achievable in the rehabilitation of some individuals with amputations, but agreeably may not be possible for all amputees to achieve
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