794 research outputs found

    Comment on "Electromagnetic dissociation of ^8B and the astrophysical S-factor for ^7Be(p,gamma)^8B"

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    Recently, Davids and Typel recommended a "low" value of S_{17}(0) based on fits to published direct and Coulomb dissociation data, in which they excluded the precise result of Junghans et al. We show that their statistical analysis is incorrect, due to a substantial underestimate of the experimental uncertainties, and leads to conclusions that are not supported by a proper analysis.Comment: submitted to Phys. Rev.

    Administrative Law

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    This article is a report of certain developments during the last two years relating to the Virginia Administrative Process Act ( the VAPA\u27\u27), which governs rulemaking and adjudication of cases by state agencies as well as judicial review of both

    SME’s Cost of Debt: A Meta-Analysis of Borrower, Creditor and Financial Statement Verification Attributes

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    Private firm financing, given the far-reaching importance of non-publicly traded companies for global output and employment, is still a relatively underexplored area. Since the seminal work of Petersen and Rajan (1994), only a small branch of research into private firms’ cost of debt has been established. We aggregate the full body of this research that has empirically investigated antecedents of private firms’ cost of debt in a meta-analysis. The foremost antecedents can be categorized into either borrower, creditor or financial statement verification attributes. Our results reveal a set of 11 highly significant and robust determinants

    Administrative Law

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    This article is a report of certain developments during the last two years relating to the Virginia Administrative Process Act ( the VAPA ), which governs rulemaking and adjudication of cases by state agencies as well as judicial review of both

    Evaluation on the axial compression mechanical properties of short BFRP laminated bamboo lumber columns

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    To investigate the effect of BFRP (basalt fiber) reinforced short laminated bamboo lumber (LBL) columns on axial compressive static performance, axial compression tests of twelve BFRP reinforced short LBL columns and three normal short LBL columns were conducted, and tensile tests of 13 BFRP were carried out. The test results show that the failure mode of BFRP reinforced short LBL columns was consistent with that of normal short LBL columns, buckling failure and adhesive layer failure. With the increase of BFRP cloth ratio, the bearing capacity of the columns increased. However, when the cloth ratio exceeded 2.3% (4 layers of BFRP), the average improvement of the load-bearing capacity was not obvious, and the reasonable cloth ratio was reached at 2.3%. The short LBL columns wrapped BFRP showed good compressive ductility, and the higher the cloth ratio of BFRP, the better the compressive ductility. Based on the suitable analysis of test data and referring to the relevant methods of fiber reinforced wood columns, the calculation model of axial compressive bearing capacity and stress-strain relationship model of BFRP reinforced short LBL columns were established. The comparison between theoretical calculation and experimental results verified the reliability and accuracy of the proposed bearing capacity calculation model and stress-strain model

    The global aerosol-cloud first indirect effect estimated using MODIS, MERRA, and AeroCom

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    Aerosol-cloud interactions (ACI) represent a significant source of forcing uncertainty in global climate models (GCMs). Estimates of radiative forcing due to ACI in Fifth Assessment Report range from −0.5 to −2.5 W m−2. A portion of this uncertainty is related to the first indirect, or Twomey, effect whereby aerosols act as nuclei for cloud droplets to condense upon. At constant liquid water content this increases the number of cloud droplets (Nd) and thus increases the cloud albedo. In this study we use remote-sensing estimates of Nd within stratocumulus regions in combination with state-of-the-art aerosol reanalysis from Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2) to diagnose how aerosols affect Nd. As in previous studies, Nd is related to sulfate mass through a power law relationship. The slope of the log-log relationship between Nd and SO4 in maritime stratocumulus is found to be 0.31, which is similar to the range of 0.2–0.8 from previous in situ studies and remote-sensing studies in the pristine Southern Ocean. Using preindustrial emissions models, the change in Nd between preindustrial and present day is estimated. Nd is inferred to have more than tripled in some regions. Cloud properties from Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate the radiative forcing due to this change in Nd. The Twomey effect operating in isolation is estimated to create a radiative forcing of −0.97 ± 0.23 W m−2 relative to the preindustrial era

    Neuroligins determine synapse maturation and function

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    Synaptogenesis, the generation and maturation of functional synapses between nerve cells, is an essential step in the development of neuronal networks in the brain. It is thought to be triggered by members of the neuroligin family of postsynaptic cell adhesion proteins, which may form transsynaptic contacts with presynaptic alpha- and beta-neurexins and have been implicated in the etiology of autism. We show that deletion mutant mice lacking neuroligin expression die shortly after birth due to respiratory failure. This respiratory failure is a consequence of reduced GABAergic/glycinergic and glutamatergic synaptic transmission and network activity in brainstem centers that control respiration. However, the density of synaptic contacts is not altered in neuroligin-deficient brains and cultured neurons. Our data show that neuroligins are required for proper synapse maturation and brain function, but not for the initial formation of synaptic contacts

    v-SNARE transmembrane domains function as catalysts for vesicle fusion.

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    Vesicle fusion is mediated by an assembly of SNARE proteins between opposing membranes, but it is unknown whether transmembrane domains (TMDs) of SNARE proteins serve mechanistic functions that go beyond passive anchoring of the force-generating SNAREpin to the fusing membranes. Here, we show that conformational flexibility of synaptobrevin-2 TMD is essential for efficient Ca(2+)-triggered exocytosis and actively promotes membrane fusion as well as fusion pore expansion. Specifically, the introduction of helix-stabilizing leucine residues within the TMD region spanning the vesicle's outer leaflet strongly impairs exocytosis and decelerates fusion pore dilation. In contrast, increasing the number of helix-destabilizing, ß-branched valine or isoleucine residues within the TMD restores normal secretion but accelerates fusion pore expansion beyond the rate found for the wildtype protein. These observations provide evidence that the synaptobrevin-2 TMD catalyzes the fusion process by its structural flexibility, actively setting the pace of fusion pore expansion
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