14,612 research outputs found

    Plume radiation program

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    Computer program determines the radiant flux to the base region of a real gas system with an axisymmetric geometry and any axisymmetric property distribution

    SPECIES I: Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars

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    The detection and subsequent characterisation of exoplanets are intimately linked to the characteristics of their host star. Therefore, it is necessary to study the star in detail in order to understand the formation history and characteristics of their companion(s). Our aims were to develop a community tool that allows the automated calculation of stellar parameters for a large number of stars, using high resolution echelle spectra and minimal photometric magnitudes, and introduce the first results in this work. We measured the equivalent widths of several iron lines and used them to solve the radiative transfer equation assuming local thermodynamic equilibrium to obtain the atmospheric parameters (TeffT_{\text{eff}}, [Fe/H], logg and ξt\xi_t). We used these values to derive the abundance of 11 chemical elements in the stellar photosphere (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu and Zn). Rotation and macroturbulent velocity were obtained using temperature calibrators and synthetic line profiles to match the observed spectra of five absorption lines. Finally, by interpolating in a grid of MIST isochrones, we derived the mass, radius and age using a Bayesian approach. SPECIES obtains bulk parameters that are in good agreement with measured values from different existing catalogues, including when different methods are used to derive them. We find excellent agreement with previous works that used similar methodologies. We find discrepancies in the chemical abundances for some elements with respect to other works, which could be produced by differences in TeffT_{\text{eff}}, or in the line list or the atomic line data used to derive them. We also obtained analytic relations to describe the correlations between different parameters, and we implemented new methods to better handle these correlations, which provides a better description of the uncertainties associated with the measurements.Comment: 28 pages, 26 figures, resubmitted to A&

    Comment on "Lattice Gluon and Ghost Propagators, and the Strong Coupling in Pure SU(3)SU(3) Yang-Mills Theory: Finite Lattice Spacing and Volume Effects"

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    The authors of ref. Phys.Rev. D94 (2016) no.1, 014502 reported about a careful analysis of the impact of lattice artifacts on the SU(3)SU(3) gauge-field propagators. In particular, they found that the low-momentum behavior of the renormalized propagators depends on the lattice bare coupling and interpreted this fact as the result of it being affected by finite lattice spacing artifacts. We do not share this interpretation and present here a different and more suitable explanation for these results

    A theoretical structure-affinity relationship study of some cannabinoid derivatives

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    Indexación: ScieloA ZINDO/1 quantum-chemical structure-affinity relationship study with the KPG model is presented for the in vitro interaction of a group of classical, indole-derived and aminoalkylindole-derived cannabinoids with CB and CB2 receptors. From this work the following conclusions are obtained. CB and CB2 CB2 receptor affinities are regulated by different mechanisms involving orbital and charge control. Nevertheless CB and CB2 classical ligands share three common features: a hydrogen bond to a lysine (for CB ) or serine (for CB), a fully aromatic ring and a branched carbon side chain. In the case of indole-derived and aminoalkylindole-derived cannabinoids orientation and alignment rules have been defined as a basis for the comparison of noncongeneric molecules. In this way it was possible to associate the location of molecular fragments of these systems with known molecular systems such as classical cannabinoids. For aminoalkyhndoles we have proposed the locus with which they bind to a second receptor site that is available to WIN-55212-2 but not to classical cannabinoids. On the basis of our results we propose a new molecule that should help to discriminate between the above two receptor sites.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072008000100013&nrm=is
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