133 research outputs found

    Radiation effects control: Eyes, skin

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    Adverse effects on the lens of the eye and the skin due to exposure to proton radiation during manned space flight were evaluated. Actual proton irradiation which might be encountered in space was simulated. Irradiation regimes included single acute exposures, daily fractionated exposures, and weekly fractionated exposures. Animals were exposed and then maintained and examined periodically until data sufficient to meet the objective were obtained. No significant skin effects were noted and no serious sight impairment was exhibited

    A Review of the Properties of Nb3Sn and Their Variation with A15 Composition, Morphology and Strain State

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    This article gives an overview of the available literature on simplified, well defined (quasi-)homogeneous laboratory samples. After more than 50 years of research on superconductivity in Nb3Sn, a significant amount of results are available, but these are scattered over a multitude of publications. Two reviews exist on the basic properties of A15 materials in general, but no specific review for Nb3Sn is available. This article is intended to provide such an overview. It starts with a basic description of the Niobium-Tin intermetallic. After this it maps the influence of Sn content on the the electron-phonon interaction strength and on the field-temperature phase boundary. The literature on the influence of Cu, Ti and Ta additions will then be briefly summarized. This is followed by a review on the effects of grain size and strain. The article is concluded with a summary of the main results.Comment: Invited Topical Review for Superconductor, Science and Technology. Provisionally scheduled for July 200

    A quasi-experimental study to mobilize rural low-income communities to assess and improve the ecological environment to prevent childhood obesity

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    Citation: Peters, P., Gold, A., Abbott, A., Contreras, D., Keim, A., Oscarson, R., . . . Mobley, A. R. (2016). A quasi-experimental study to mobilize rural low-income communities to assess and improve the ecological environment to prevent childhood obesity. Bmc Public Health, 16, 7. doi:10.1186/s12889-016-3047-4Background: The Ecological Model of Childhood Overweight focuses on characteristics that could affect a child's weight status in relation to the multiple environments surrounding that child. A community coaching approach allows community groups to identify their own strengths, priorities and identity. Little to no research currently exists related to community-based efforts inclusive of community coaching in creating environmental change to prevent childhood obesity particularly in rural communities. Methods: A quasi-experimental study will be conducted with low-income, rural communities (n = 14) in the North Central region of the United States to mobilize capacity in communities to create and sustain an environment of healthy eating and physical activity to prevent childhood obesity. Two rural communities within seven Midwestern states (IN, KS, MI, OH, ND, SD, WI) will be randomly assigned to serve as an intervention or comparison community. Coalitions will complete assessments of their communities, choose from evidence-based approaches, and implement nutrition and physical activity interventions each year to prevent childhood obesity with emphasis on policy, system or environmental changes over four years. Only intervention coalitions will receive community coaching from a trained coach. Outcomes will be assessed at baseline, annually and project end using previously validated instruments and include coalition self-assessments, parental perceptions regarding the built environment, community, neighborhood, and early childhood environments, self-reflections from coaches and project staff, ripple effect mapping with coalitions and, final interviews of key stakeholders and coaches. A mixed-methods analysis approach will be used to evaluate if Community Coaching enhances community capacity to create and sustain an environment to support healthy eating and physical activity for young children. ANOVA or corresponding non-parametric tests will be used to analyze quantitative data relating to environmental change with significance set at P < .05. Dominant emergent themes from the qualitative data will be weaved together with quantitative data to develop a theoretical model representing how communities were impacted by the project. Discussion: This project will yield data and best practices that could become a model for community development based approaches to preventing childhood obesity in rural communities

    Electronic anisotropy, magnetic field-temperature phase diagram and their dependence on resistivity in c-axis oriented MgB2 thin films

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    An important predicted, but so far uncharacterized, property of the new superconductor MgB2 is electronic anisotropy arising from its layered crystal structure. Here we report on three c-axis oriented thin films, showing that the upper critical field anisotropy ratio Hc2par/Hc2perp is 1.8 to 2.0, the ratio increasing with higher resistivity. Measurements of the magnetic field-temperature phase diagram show that flux pinning disappears at H* ~ 0.8Hc2perp(T) in untextured samples. Hc2par(0) is strongly enhanced by alloying to 39 T for the highest resistivity film, more than twice that seen in bulk samples.Comment: 5 pages Acrobat 3.02 pd

    Thin Film Magnesium Boride Superconductor with Very High Critical Current Density and Enhanced Irreversibility Field

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    The discovery of superconductivity at 39 K in magnesium diboride offers the possibility of a new class of low-cost, high-performance superconducting materials for magnets and electronic applications. With twice the critical temperature of Nb_3Sn and four times that of Nb-Ti alloy, MgB_2 has the potential to reach much higher fields and current densities than either of these technological superconductors. A vital prerequisite, strongly linked current flow, has already been demonstrated even at this early stage. One possible drawback is the observation that the field at which superconductivity is destroyed is modest. Further, the field which limits the range of practical applications, the irreversibility field H*(T), is ~7 T at liquid helium temperature (4.2 K), significantly lower than ~10 T for Nb-Ti and ~20 T for Nb_3Sn. Here we show that MgB_2 thin films can exhibit a much steeper temperature dependence of H*(T) than is observed in bulk materials, yielding H*(4.2 K) above 14 T. In addition, very high critical current densities at 4.2 K, 1 MA/cm_2 at 1 T and 10_5 A/cm_2 at 10 T, are possible. These data demonstrate that MgB_2 has credible potential for high-field superconducting applications.Comment: 4 pages pdf, submitted to Nature 3/20/0

    Characterization of 4-HNE Modified L-FABP Reveals Alterations in Structural and Functional Dynamics

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    4-Hydroxynonenal (4-HNE) is a reactive α,β-unsaturated aldehyde produced during oxidative stress and subsequent lipid peroxidation of polyunsaturated fatty acids. The reactivity of 4-HNE towards DNA and nucleophilic amino acids has been well established. In this report, using proteomic approaches, liver fatty acid-binding protein (L-FABP) is identified as a target for modification by 4-HNE. This lipid binding protein mediates the uptake and trafficking of hydrophobic ligands throughout cellular compartments. Ethanol caused a significant decrease in L-FABP protein (P<0.001) and mRNA (P<0.05), as well as increased poly-ubiquitinated L-FABP (P<0.001). Sites of 4-HNE adduction on mouse recombinant L-FABP were mapped using MALDI-TOF/TOF mass spectrometry on apo (Lys57 and Cys69) and holo (Lys6, Lys31, His43, Lys46, Lys57 and Cys69) L-FABP. The impact of 4-HNE adduction was found to occur in a concentration-dependent manner; affinity for the fluorescent ligand, anilinonaphthalene-8-sulfonic acid, was reduced from 0.347 µM to Kd1 = 0.395 µM and Kd2 = 34.20 µM. Saturation analyses revealed that capacity for ligand is reduced by approximately 50% when adducted by 4-HNE. Thermal stability curves of apo L-FABP was also found to be significantly affected by 4-HNE adduction (ΔTm = 5.44°C, P<0.01). Computational-based molecular modeling simulations of adducted protein revealed minor conformational changes in global protein structure of apo and holo L-FABP while more apparent differences were observed within the internal binding pocket, revealing reduced area and structural integrity. New solvent accessible portals on the periphery of the protein were observed following 4-HNE modification in both the apo and holo state, suggesting an adaptive response to carbonylation. The results from this study detail the dynamic process associated with L-FABP modification by 4-HNE and provide insight as to how alterations in structural integrity and ligand binding may a contributing factor in the pathogenesis of ALD

    Computed tomography as an adjunct to ultrasound in the diagnosis of acute acalculous cholecystitis

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    The sonographic and computed tomographic (CT) findings were reviewed in 17 patients with acute acalculous cholecystitis (AAC) over a 6-year period from 1984 to 1989. Of the six patients in whom both ultrasound and CT were performed, CT revealed marked gallbladder (GB) wall abnormalities, including perforation, and pericholecystic fluid collections in five patients not demonstrated by sonography. Of the total group, five patients had GB wall thicknesses of ≤ 3 mm (normal) at pathologic examination, which demonstrated a spectrum of disease ranging from acute hemorrhagic/necrotizing, to gangrenous acalculous cholecystitis with perforation. Sonography was falsely negative or significantly underestimated the severity of AAC in seven of the 13 patients examined by sonography. CT because of its superior ability to assess pericholecystic inflammation may provide additional diagnostic information even after a thorough sonographic study in cases of AAC.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48138/1/261_2005_Article_BF01887331.pd

    Developments in Low Temperature Superconductor Materials at Cabot Performance Materials

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