6,692 research outputs found

    Applications of satellite snow cover in computerized short-term streamflow forecasting

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    A procedure is described whereby the correlation between: (1) satellite derived snow-cover depletion and (2) residual snowpack water equivalent, can be used to update computerized residual flow forecasts for the Conejos River in southern Colorado

    Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels

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    The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity filter of the channel is used. The selectivity filter of this channel type contains aspartate (D), glutamate (E), lysine (K), and alanine (A) residues (the DEKA locus). We use Grand Canonical Monte Carlo simulations to compute equilibrium binding selectivity in the selectivity filter and to obtain various terms of the excess chemical potential from a particle insertion procedure based on Widom's method. We show that K+^{+} ions in competition with Na+^{+} are efficiently excluded from the selectivity filter due to entropic hard sphere exclusion. The dielectric constant of protein has no effect on this selectivity. Ca2+^{2+} ions, on the other hand, are excluded from the filter due to a free energetic penalty which is enhanced by the low dielectric constant of protein.Comment: 14 pages, 7 figure

    A Two-point Diagnostic for the HII Galaxy Hubble Diagram

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    A previous analysis of starburst-dominated HII Galaxies and HII regions has demonstrated a statistically significant preference for the Friedmann-Robertson-Walker cosmology with zero active mass, known as the R_h=ct universe, over LCDM and its related dark-matter parametrizations. In this paper, we employ a 2-point diagnostic with these data to present a complementary statistical comparison of R_h=ct with Planck LCDM. Our 2-point diagnostic compares---in a pairwise fashion---the difference between the distance modulus measured at two redshifts with that predicted by each cosmology. Our results support the conclusion drawn by a previous comparative analysis demonstrating that R_h=ct is statistically preferred over Planck LCDM. But we also find that the reported errors in the HII measurements may not be purely Gaussian, perhaps due to a partial contamination by non-Gaussian systematic effects. The use of HII Galaxies and HII regions as standard candles may be improved even further with a better handling of the systematics in these sources.Comment: 7 pages, 6 figures, 2 tables. Accepted for publication in MNRA
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