6,246 research outputs found

    Transport model analysis of particle correlations in relativistic heavy ion collisions at femtometer scales

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    The pion source as seen through HBT correlations at RHIC energies is investigated within the UrQMD approach. We find that the calculated transverse momentum, centrality, and system size dependence of the Pratt-HBT radii RLR_L and RSR_S are reasonably well in line with experimental data. The predicted ROR_O values in central heavy ion collisions are larger as compared to experimental data. The corresponding quantity RO2RS2\sqrt{R_O^{2}-R_S^{2}} of the pion emission source is somewhat larger than experimental estimates.Comment: 12 pages, 5 figures, to be published in PR

    A Data-Driven Analysis of Blockchain Systems' Public Online Communications on GDPR

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    After the European Union's new General Data Protection Regulation (GDPR) became applicable in May 2018,concerns about the legal compliance of public blockchain systems with rights guaranteed by GDPR have emerged, e.g., on the "right to be forgotten". In order to better understand how the blockchain sector sees the challenges raised by GDPR and how such their communications could influence their users, this paper reports our data-driven analysis of GDPR-related public online communications of blockchain developers and service providers.Our analysis covers 314 public blockchain systems, and two different online communication channels: legal documents including privacy policies, T&C (Terms and Conditions) documents and other similar legal documents published on systems’ official websites and public tweets of their official Twitter accounts.Our analysis revealed that only a minority (86/314≈27.5%)of the investigated blockchain systems had covered GDPR at least once using one or both communication channels. Among the 86systems, only 27 systems (8.6%) had at least one legal document that actually talks about GDPR for the corresponding blockchain system. We noticed a systematic lack of detail about why and how the GDPR compliance issue was addressed, and most systems made questionable statements about GDPR compliance. There sults are surprising considering that the GDPR was enacted in 2016 and has been in effect since May 2018

    4-Aminopyridine Decreases Progesterone Production by Porcine Granulosa Cells

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    BACKGROUND: Ion channels occur as large families of related genes with cell-specific expression patterns. Granulosa cells have been shown to express voltage-gated potassium channels from more than one family. The purpose of this study was to determine the effects of 4-aminopyridine (4-AP), an antagonist of KCNA but not KCNQ channels. METHODS: Granulosa cells were isolated from pig follicles and cultured with 4-AP, alone or in combination with FSH, 8-CPT-cAMP, estradiol 17β, and DIDS. Complimentary experiments determined the effects of 4-AP on the spontaneously established pig granulosa cell line PGC-2. Granulosa cell or PGC-2 function was assessed by radio-immunoassay of media progesterone accumulation. Cell viability was assessed by trypan blue exclusion. Drug-induced changes in cell membrane potential and intracellular potassium concentration were documented by spectrophotometric determination of DiBAC(4)(3) and PBFI fluorescence, respectively. Expression of proliferating cell nuclear antigen (PCNA) and steroidogenic acute regulatory protein (StAR) was assessed by immunoblotting. Flow cytometry was also used to examine granulosa cell viability and size. RESULTS: 4-AP (2 mM) decreased progesterone accumulation in the media of serum-supplemented and serum-free granulosa cultures, but inhibited cell proliferation only under serum-free conditions. 4-AP decreased the expression of StAR, the production of cAMP and the synthesis of estradiol by PGC-2. Addition of either 8-CPT-cAMP or estradiol 17β to serum-supplemented primary cultures reduced the inhibitory effects of 4-AP. 4-AP treatment was also associated with increased cell size, increased intracellular potassium concentration, and hyperpolarization of resting membrane potential. The drug-induced hyperpolarization of resting membrane potential was prevented either by decreasing extracellular chloride or by adding DIDS to the media. DIDS also prevented 4-AP inhibition of progesterone production. CONCLUSION: 4-AP inhibits basal and FSH-stimulated progesterone production by pig granulosa cells via drug action at multiple interacting steps in the steroidogenic pathway. These inhibitory effects of 4-AP on steroidogenesis may reflect drug-induced changes in intracellular concentrations of K(+)and Cl(- )as well as granulosa cell resting membrane potential

    Validated age and growth estimates for Carcharhinus obscurus in the northwestern Atlantic Ocean, with pre- and post management growth comparisons

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    This paper is not subject to U.S. copyright. The definitive version was published in Environmental Biology of Fishes 97 (2014): 881-896, doi:10.1007/s10641-013-0189-4.Age and growth estimates for the dusky shark, Carcharhinus obscurus, were derived from vertebral centra collected in the northwestern Atlantic Ocean. Sample collection spanned the years prior to and following the implementation of management measures (1963–2010). Growth was compared pre- and post- population depletion and pre- and post- management to investigate the possibility of density-mediated shifts in age and growth parameters over time. There was no evidence of difference between periods for either sex. Additionally, bomb radiocarbon dating was used to determine the periodicity of band pair formation. Results support the traditional interpretation of annual band pairs up to approximately 11 years of age. After this time, vertebral counts considerably underestimate true age. Maximum validated ages were estimated to be between 38 and 42 years of age (an increase of 15 to 19 years over the band count estimates), confirming longevity to at least 42 years of age. Growth curves estimated using only validated data were compared to those generated using band pair counts. Logistic growth parameters derived from validated vertebral length-at-age data were L ∞  = 261.5 cm FL, L o  = 85.5 cm, t o  = 4.89 year and g = 0.15 year−1 for the sexes combined. Revised estimates of age at maturity were 17.4 years for males and 17.6 years for females

    A Turnover in the Galaxy Main Sequence of Star Formation at M1010MM_{*} \sim 10^{10} M_{\odot} for Redshifts z<1.3z < 1.3

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    The relationship between galaxy star formation rates (SFR) and stellar masses (MM_\ast) is re-examined using a mass-selected sample of \sim62,000 star-forming galaxies at z1.3z \le 1.3 in the COSMOS 2-deg2^2 field. Using new far-infrared photometry from HerschelHerschel-PACS and SPIRE and SpitzerSpitzer-MIPS 24 μ\mum, along with derived infrared luminosities from the NRK method based on galaxies' locations in the restframe color-color diagram (NUVr)(NUV - r) vs. (rK)(r - K), we are able to more accurately determine total SFRs for our complete sample. At all redshifts, the relationship between median SFRSFR and MM_\ast follows a power-law at low stellar masses, and flattens to nearly constant SFR at high stellar masses. We describe a new parameterization that provides the best fit to the main sequence and characterizes the low mass power-law slope, turnover mass, and overall scaling. The turnover in the main sequence occurs at a characteristic mass of about M01010MM_{0} \sim 10^{10} M_{\odot} at all redshifts. The low mass power-law slope ranges from 0.9-1.3 and the overall scaling rises in SFR as a function of (1+z)4.12±0.10(1+z)^{4.12 \pm 0.10}. A broken power-law fit below and above the turnover mass gives relationships of SFRM0.88±0.06SFR \propto M_{*}^{0.88 \pm 0.06} below the turnover mass and SFRM0.27±0.04SFR \propto M_{*}^{0.27 \pm 0.04} above the turnover mass. Galaxies more massive than M1010 MM_\ast \gtrsim 10^{10}\ M_{\rm \odot} have on average, a much lower specific star formation rate (sSFR) than would be expected by simply extrapolating the traditional linear fit to the main sequence found for less massive galaxies.Comment: 16 pages, 7 figures. Accepted for publication in Ap

    Classification of hyperbolic Dynkin diagrams, root lengths and Weyl group orbits

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    We give a criterion for a Dynkin diagram, equivalently a generalized Cartan matrix, to be symmetrizable. This criterion is easily checked on the Dynkin diagram. We obtain a simple proof that the maximal rank of a Dynkin diagram of compact hyperbolic type is 5, while the maximal rank of a symmetrizable Dynkin diagram of compact hyperbolic type is 4. Building on earlier classification results of Kac, Kobayashi-Morita, Li and Sa\c{c}lio\~{g}lu, we present the 238 hyperbolic Dynkin diagrams in ranks 3-10, 142 of which are symmetrizable. For each symmetrizable hyperbolic generalized Cartan matrix, we give a symmetrization and hence the distinct lengths of real roots in the corresponding root system. For each such hyperbolic root system we determine the disjoint orbits of the action of the Weyl group on real roots. It follows that the maximal number of disjoint Weyl group orbits on real roots in a hyperbolic root system is 4.Comment: J. Phys. A: Math. Theor (to appear

    JC Virus Antibody and Viremia as Predictors of Progressive Multifocal Leukoencephalopathy in Human Immunodeficiency Virus-1-Infected Individuals

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    We examined whether prediagnostic John Cunningham virus (JCV) antibodies and viremia are predictors of progressive multifocal leukoencephalopathy (PML) in 83 PML cases and 240 human immunodeficiency virus (HIV) disease-matched controls. JCV viremia was not predictive of PML, but some patients showed higher anti-JCV immunoglobulin G (IgG) responses 6 months prior to diagnosi
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