512 research outputs found

    Deconvolution and analysis of wide-angle longwave radiation data from Nimbus 6 Earth radiation budget experiment for the first year

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    One year of longwave radiation data from July 1975 through June 1976 from the Nimbus 6 satellite Earth radiation budget experiment is analyzed by representing the radiation field by a spherical harmonic expansion. The data are from the wide field of view instrument. Contour maps of the longwave radiation field and spherical harmonic coefficients to degree 12 and order 12 are presented for a 12 month data period

    Diversity, Distribution, and Expression of Diazotroph nifH Genes in Oxygen-Deficient Waters of the Arabian Sea

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    The Arabian Sea oxygen minimum zone (OMZ), the largest suboxic region in the world\u27s oceans, is responsible for up to half of the global mesopelagic fixed nitrogen ( N ) loss from the ocean via denitrification and anammox. Dinitrogen (N2) fixation is usually attributed to cyanobacteria in the surface ocean. Model prediction and physiological inhibition of N2 fixation by oxygen, however, suggest that N2 fixation should be enhanced near the oxygen-deficient zone (ODZ) of the Arabian Sea. N2 fixation and cyanobacterial nifH genes (the gene encoding dinitrogenase reductase) have been reported in surface waters overlying the Arabian Sea ODZ. Here, water samples from depths above and within the Arabian Sea ODZ were examined to explore the distribution, diversity, and expression of nifH genes. In surface waters, nifH DNA and cDNA sequences related to Trichodesmium, a diazotroph known to occur and fix N2 in the Arabian Sea, were detected. Proteobacterial nifH phylotypes (DNA but not cDNA) were also detected in surface waters. Proteobacterial nifH DNA and cDNA sequences, as well as nifH DNA and cDNA sequences related to strictly anaerobic N -fixers, were obtained from oxygen-deficient depths. This first report of nifH gene expression in subsurface low-oxygen waters suggests that there is potential for active N2 fixation by several phylogenetically and potentially metabolically diverse microorganisms in pelagic OMZs

    Multiple Metabolisms Constrain the Anaerobic Nitrite Budget in the Eastern Tropical South Pacific

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    The Eastern Tropical South Pacific is one of the three major oxygen deficient zones (ODZs) in the global ocean and is responsible for approximately one third of marine water column nitrogen loss. It is the best studied of the ODZs and, like the others, features a broad nitrite maximum across the low oxygen layer. How the microbial processes that produce and consume nitrite in anoxic waters interact to sustain this feature is unknown. Here we used 15N-tracer experiments to disentangle five of the biologically mediated processes that control the nitrite pool, including a high-resolution profile of nitrogen loss rates. Nitrate reduction to nitrite likely depended on organic matter fluxes, but the organic matter did not drive detectable rates of denitrification to N2. However, multiple lines of evidence show that denitrification is important in shaping the biogeochemistry of this ODZ. Significant rates of anaerobic nitrite oxidation at the ODZ boundaries were also measured. Lodate was a potential oxidant that could support part of this nitrite consumption pathway. We additionally observed N2 production from labeled cyanate and postulate that anammox bacteria have the ability to harness cyanate as another form of reduced nitrogen rather than relying solely on ammonification of complex organic matter. The balance of the five anaerobic rates measured—anammox, denitrification, nitrate reduction, nitrite oxidation, and dissimilatory nitrite reduction to ammonium—is sufficient to reproduce broadly the observed nitrite and nitrate profiles in a simple one-dimensional model but requires an additional source of reduced nitrogen to the deeper ODZ to avoid ammonium overconsumption. ©2017. American Geophysical Union. All Rights Reserved

    Revisiting the transatlantic divergence over GMOs: Toward a cultural-political analysis

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    'Revisiting the transatlantic divergence over GMOs: towards a cultural-political analysis' applies a constructivist perspective to the persistent transatlantic divergence over the regulation of GM foods and crops. Political economy and institutionalism have so far dominated the literature. Notwithstanding their crucial insights, this article argues that to achieve a better understanding of the nature and depth of transatlantic regulatory divergence, one should also study prevalent cultural values and identity-related public concerns regarding food and agriculture. These factors can be identified in public opinion trends and have fuelled Europeans' resistance, while contributing to relative regulatory stability in the US. By conceptualizing cultural contexts as catalytic structures, the article also differs from more explicitly discursive accounts of political mobilization. The cultural politics of agricultural biotechnology (agbiotech) relies both on pre-existing values and identities, on the one hand, and on the strategies (and material or other power resources) of political agents

    Advanced Fuels for LWRs: Fully-Ceramic Microencapsulated and Related Concepts FY 2012 Interim Report

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    This report summarizes the progress in the Deep Burn project at Idaho National Laboratory during the first half of fiscal year 2012 (FY2012). The current focus of this work is on Fully-Ceramic Microencapsulated (FCM) fuel containing low-enriched uranium (LEU) uranium nitride (UN) fuel kernels. UO2 fuel kernels have not been ruled out, and will be examined as later work in FY2012. Reactor physics calculations confirmed that the FCM fuel containing 500 mm diameter kernels of UN fuel has positive MTC with a conventional fuel pellet radius of 4.1 mm. The methodology was put into place and validated against MCNP to perform whole-core calculations using DONJON, which can interpolate cross sections from a library generated using DRAGON. Comparisons to MCNP were performed on the whole core to confirm the accuracy of the DRAGON/DONJON schemes. A thermal fluid coupling scheme was also developed and implemented with DONJON. This is currently able to iterate between diffusion calculations and thermal fluid calculations in order to update fuel temperatures and cross sections in whole-core calculations. Now that the DRAGON/DONJON calculation capability is in place and has been validated against MCNP results, and a thermal-hydraulic capability has been implemented in the DONJON methodology, the work will proceed to more realistic reactor calculations. MTC calculations at the lattice level without the correct burnable poison are inadequate to guarantee zero or negative values in a realistic mode of operation. Using the DONJON calculation methodology described in this report, a startup core with enrichment zoning and burnable poisons will be designed. Larger fuel pins will be evaluated for their ability to (1) alleviate the problem of positive MTC and (2) increase reactivity-limited burnup. Once the critical boron concentration of the startup core is determined, MTC will be calculated to verify a non-positive value. If the value is positive, the design will be changed to require less soluble boron by, for example, increasing the reactivity hold-down by burnable poisons. Then, the whole core analysis will be repeated until an acceptable design is found. Calculations of departure from nucleate boiling ratio (DNBR) will be included in the safety evaluation as well. Once a startup core is shown to be viable, subsequent reloads will be simulated by shuffling fuel and introducing fresh fuel. The PASTA code has been updated with material properties of UN fuel from literature and a model for the diffusion and release of volatile fission products from the SiC matrix material . Preliminary simulations have been performed for both normal conditions and elevated temperatures. These results indicated that the fuel performs well and that the SiC matrix has a good retention of the fission products. The path forward for fuel performance work includes improvement of metallic fission product release from the kernel. Results should be considered preliminary and further validation is required

    Semiconductor Noise

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    Contains reports on two research projects

    Differences in career paths and attributes of pharmacists completing a community pharmacy residency program (CPRP)

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    Objective: To determine any differences in career paths and career attributes of pharmacists who have completed a PGY1 community pharmacy residency program (CPRP) as compared to those that have not completed a PGY1 CPRP. Methods: A web-based survey evaluating various aspects of community pharmacists’ careers was distributed to 274 CPRP graduates in addition to a random sample of 7,376 community pharmacists. The survey contained 32 questions evaluating various career attributes. Questions that assessed level of agreement were on a 6-point Likert-type Scale (1=strongly disagree; 6=strongly agree). Results: A total of 353 participants completed the survey, with 224 indicating that they had not completed a CPRP. Pharmacists who completed a CPRP responded that they spend significantly more time on patient care services, teaching, and research, and spend less time dispensing medications compared to those that have not completed a CPRP. Compared to those that did not complete a CPRP, CPRP graduates were less likely to agree that current level of workload negatively impacts job performance, motivation to work, job satisfaction, mental/emotional health, and physical health. Conclusion: Pharmacists completing a CPRP noted significant differences in their current employment and job responsibilities. Additional expansion and education regarding the importance of CPRPs should be considered

    Endothelial function and urine albumin levels among asymptomatic Mexican-Americans and non-Hispanic whites

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    <p>Abstract</p> <p>Background-</p> <p>Mexican-Americans (MA) exhibit increases in various cardiovascular disease (CVD) risk factors compared to non-Hispanic Whites (NHW), yet are reported to have lower CVD mortality rates. Our aim was to help explain this apparent paradox by evaluating endothelial function and urine albumin levels in MA and NHW.</p> <p>Methods-</p> <p>One hundred-five MA and 100 NHW adults were studied by brachial artery flow-mediated dilatation (FMD), blood and urine tests. Participants were studied by ultrasound-determined brachial artery flow-mediated dilatation (FMD), blood and urine tests, at a single visit.</p> <p>Results-</p> <p>Despite higher BMI and triglycerides in MA, MA demonstrated higher FMD than did NHW (9.1 ± 7.3% vs. 7.1 ± 6.3%, p < 0.04). Among MA, urinary albumin was consistently lower in participants with FMD ≥ 7% FMD versus < 7% FMD (p < 0.006). In multivariate analyses in MA men, urinary albumin was inversely related to FMD (r = -0.26, p < 0.05), as were BMI and systolic blood pressure. In MA women, urinary albumin:creatinine ratio was an independent inverse predictor of FMD (p < 0.05 ).</p> <p>Conclusion-</p> <p>To our knowledge, this is the first study to analyze, in asymptomatic adults, the relation of MA and NHW ethnicity to FMD and urine albumin levels. The findings confirm ethnic differences in these important subclinical CVD measures.</p
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