439 research outputs found

    A new technique for elucidating β\beta-decay schemes which involve daughter nuclei with very low energy excited states

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    A new technique of elucidating β\beta-decay schemes of isotopes with large density of states at low excitation energies has been developed, in which a Broad Energy Germanium (BEGe) detector is used in conjunction with coaxial hyper-pure germanium detectors. The power of this technique has been demonstrated on the example of 183Hg decay. Mass-separated samples of 183Hg were produced by a deposition of the low-energy radioactive-ion beam delivered by the ISOLDE facility at CERN. The excellent energy resolution of the BEGe detector allowed γ\gamma rays energies to be determined with a precision of a few tens of electronvolts, which was sufficient for the analysis of the Rydberg-Ritz combinations in the level scheme. The timestamped structure of the data was used for unambiguous separation of γ\gamma rays arising from the decay of 183Hg from those due to the daughter decays

    Mutational Analysis of the Nitrogenase Carbon Monoxide Protective Protein CowN Reveals That a Conserved C‑Terminal Glutamic Acid Residue Is Necessary for Its Activity

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    Nitrogenase is the only enzyme that catalyzes the reduction of nitrogen gas into ammonia. Nitrogenase is tightly inhibited by the environmental gas carbon monoxide (CO). Many nitrogen fixing bacteria protect nitrogenase from CO inhibition using the protective protein CowN. This work demonstrates that a conserved glutamic acid residue near the C-terminus of Gluconacetobacter diazotrophicus CowN is necessary for its function. Mutation of the glutamic acid residue abolishes both CowN’s protection against CO inhibition and the ability of CowN to bind to nitrogenase. In contrast, a conserved C-terminal cysteine residue is not important for CO protection by CowN. Overall, this work uncovers structural features in CowN that are required for its function and provides new insights into its nitrogenase binding and CO protection mechanism

    Plasma Magnetohydrodynamics and Energy Conversion

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    Contains reports on seven research projects.U. S. Air Force (Aeronautical Systems Division) under Contract AF33 (615)-1083 with the Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, OhioNational Science Foundation (Grant GK-57

    The effects of financialisation and financial development on investment: Evidence from firm-level data in Europe

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    In this paper we estimate the effects of financialization on physical investment in selected western European countries using panel data based on the balance-sheets of publicly listed non-financial companies (NFCs) supplied by Worldscope for the period 1995-2015. We find robust evidence of an adverse effect of both financial payments (interests and dividends) and financial incomes on investment in fixed assets by the NFCs. This finding is robust for both the pool of all Western European firms and single country estimations. The negative impacts of financial incomes are non-linear with respect to the companies’ size: financial incomes crowd-out investment in large companies, and have a positive effect on the investment of only small, relatively more credit-constrained companies. Moreover, we find that a higher degree of financial development is associated with a stronger negative effect of financial incomes on companies’ investment. This finding challenges the common wisdom on ‘finance-growth nexus’. Our findings support the ‘financialization thesis’ that the increasing orientation of the non-financial sector towards financial activities is ultimately leading to lower physical investment, hence to stagnant or fragile growth, as well as long term stagnation in productivity

    Plasma Magnetohydrodynamics and Energy Conversion

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    Contains research objectives and reports on six research projects.U. S. Air Force (Aeronautical Systems Division) under Contract AF33 (615)-1083Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, OhioNational Science Foundation (Grant G-24073)National Institutes of Health (Grant No. 5 TI HE 5550-02

    hCALCRL mutation causes autosomal recessive nonimmune hydrops fetalis with lymphatic dysplasia

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    We report the first case of nonimmune hydrops fetalis (NIHF) associated with a recessive, in-frame deletion of V205 in the G protein–coupled receptor, Calcitonin Receptor-Like Receptor (hCALCRL). Homozygosity results in fetal demise from hydrops fetalis, while heterozygosity in females is associated with spontaneous miscarriage and subfertility. Using molecular dynamic modeling and in vitro biochemical assays, we show that the hCLR(V205del) mutant results in misfolding of the first extracellular loop, reducing association with its requisite receptor chaperone, receptor activity modifying protein (RAMP), translocation to the plasma membrane and signaling. Using three independent genetic mouse models we establish that the adrenomedullin–CLR–RAMP2 axis is both necessary and sufficient for driving lymphatic vascular proliferation. Genetic ablation of either lymphatic endothelial Calcrl or nonendothelial Ramp2 leads to severe NIHF with embryonic demise and placental pathologies, similar to that observed in humans. Our results highlight a novel candidate gene for human congenital NIHF and provide structure–function insights of this signaling axis for human physiology

    Plasma Magnetohydrodynamics and Energy Conversion

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    Contains reports on eight research projects.National Science Foundation (Grant G-24073)United States Air Force, Aeronautical Systems Division, Aeronautical Accessories Laboratory, Wright-Patterson Air Force Base (Contract AF33(616)-7624)United States Air Force, Office of Scientific Research of the Office of Aerospace Research (Research Grant No. 62-308

    The scale of population structure in Arabidopsis thaliana

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    The population structure of an organism reflects its evolutionary history and influences its evolutionary trajectory. It constrains the combination of genetic diversity and reveals patterns of past gene flow. Understanding it is a prerequisite for detecting genomic regions under selection, predicting the effect of population disturbances, or modeling gene flow. This paper examines the detailed global population structure of Arabidopsis thaliana. Using a set of 5,707 plants collected from around the globe and genotyped at 149 SNPs, we show that while A. thaliana as a species self-fertilizes 97% of the time, there is considerable variation among local groups. This level of outcrossing greatly limits observed heterozygosity but is sufficient to generate considerable local haplotypic diversity. We also find that in its native Eurasian range A. thaliana exhibits continuous isolation by distance at every geographic scale without natural breaks corresponding to classical notions of populations. By contrast, in North America, where it exists as an exotic species, A. thaliana exhibits little or no population structure at a continental scale but local isolation by distance that extends hundreds of km. This suggests a pattern for the development of isolation by distance that can establish itself shortly after an organism fills a new habitat range. It also raises questions about the general applicability of many standard population genetics models. Any model based on discrete clusters of interchangeable individuals will be an uneasy fit to organisms like A. thaliana which exhibit continuous isolation by distance on many scales
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