3,682 research outputs found

    Transformations between the theoretical and observational planes in the HST-NICMOS and WFPC2 photometric systems

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    Color-temperature relations and bolometric corrections in the HST-NICMOS F1110W, F160W and F222M and in the WFPC2 F439W, F555W and F814W photometric systems, using two different sets of model atmospheres, have been derived. This database of homogeneous, self-consistent transformations between the theoretical and observational planes also allows combinations of visual and infrared quantities, without any further transformation between the two different photometric systems. The behavior of the inferred quantities with varying the stellar parameters, the adopted model atmospheres and the instrumental configurations are investigated. Suitable relations to transform colors and bolometric corrections from HST to ground-based photometric systems are also provided.Comment: 22 pages, 14 figure

    Phylogenetically distinct equine influenza viruses show different tropism for the swine respiratory tract

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    Influenza A viruses circulate in a wide range of animals. H3N8 equine influenza virus (EIV) is an avian-origin virus that has established in dogs as canine influenza virus (CIV) and has also been isolated from camels and pigs. Previous work suggests that adaptive mutations acquired during EIV evolution might have played a role in CIV emergence. Given the potential role of pigs as a source of human infections, we determined the ability of H3N8 EIVs to replicate in pig cell lines and in respiratory explants. We show that evolutionary distinct EIVs display different infection phenotypes along the pig respiratory tract, but not in cell lines. Our results suggest that EIV displays a dynamic host range along its evolutionary history, supporting the view that evolutionary processes play important roles on host range and tropism, and also underscore the utility of using explants cultures to study influenza pathogenesis

    The Effect of Salience on Co-variation in Brazilian Portuguese

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    This paper analyzes cross-correlations among six variables of Brazilian Portuguese (the pronunciation of nasal /e/, coda r-retroflexion, coda r-deletion, NP agreement, 3rd person plural subject-verb agreement, and 1st person plural subject-verb agreement), with the objective of identifying constraints that promote the co-occurrence of sociolinguistic variants in individual speakers’ speech. We focus on the perspective of structural cohesion, and show that co-variability is conditioned not only by structural similarities among dependent variables (such as agreement processes or coda weakening), but also by general linguistic constraints that operate across multiple variables, such as phonic salience (Naro 1981, Scherre 1988, Naro et al. 1999). Finally, we suggest that markedness may be a more general linguistic principle underlying co-variation

    Analisis Dan Evaluasi Jabatan Pada Perusahaan Tekstil

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    This research presents job analysis and evaluation in order to design salary structure of a textile company. Preliminary interview, questionnaire, observation and focus group discussions were applied for job analysis. In addition, a point factor system and analytical hierarchy process methods were used for doing job evaluation. Job description and job specification and basic salary of each job were produced in this study

    An In Situ Surface-Enhanced Infrared Absorption Spectroscopy Study of Electrochemical CO2 Reduction: Selectivity Dependence on Surface C-Bound and O-Bound Reaction Intermediates

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    The CO_{2} electro-reduction reaction (CORR) is a promising avenue to convert greenhouse gases into high-value fuels and chemicals, in addition to being an attractive method for storing intermittent renewable energy. Although polycrystalline Cu surfaces have long known to be unique in their capabilities of catalyzing the conversion of CO_{2} to higher-order C1 and C2 fuels, such as hydrocarbons (CH_{4}, C_{2}H_{4} etc.) and alcohols (CH_{3}OH, C_{2}H_{5}OH), product selectivity remains a challenge. In this study, we select three metal catalysts (Pt, Au, Cu) and apply in situ surface enhanced infrared absorption spectroscopy (SEIRAS) and ambient-pressure X-ray photoelectron spectroscopy (APXPS), coupled to density-functional theory (DFT) calculations, to get insight into the reaction pathway for the CORR. We present a comprehensive reaction mechanism for the CORR, and show that the preferential reaction pathway can be rationalized in terms of metal-carbon (M-C) and metal-oxygen (M-O) affinity. We show that the final products are determined by the configuration of the initial intermediates, C-bound and O-bound, which can be obtained from CO_{2} and (H)CO_{3}, respectively. C1 hydrocarbons are produced via OCH_{3, ad} intermediates obtained from O-bound CO_{3, ad} and require a catalyst with relatively high affinity for O-bound intermediates. Additionally, C2 hydrocarbon formation is suggested to result from the C-C coupling between C-bound CO_{ad} and (H)CO_{ad}, which requires an optimal affinity for the C-bound species, so that (H)CO_{ad} can be further reduced without poisoning the catalyst surface. Our findings pave the way towards a design strategy for CORR catalysts with improved selectivity, based on this experimental/theoretical reaction mechanisms that have been identified

    The First Detailed Abundances for M giants in Baade's Window from Infrared Spectroscopy

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    We report the first abundance analysis of 14 M giant stars in the Galactic bulge, based on R=25,000 infrared spectroscopy (1.5-1.8um) using NIRSPEC at the Keck II telescope. Because some of the bulge M giants reach high luminosities and have very late spectral type, it has been suggested that they are the progeny of only the most metal rich bulge stars, or possibly members of a younger bulge population. We find the iron abundance and composition of the M giants are similar to those of the K giants that have abundances determined from optical high resolution spectroscopy: =-0.190 +/- 0.020 with a 1-sigma dispersion of 0.08 +/- 0.015. Comparing our bulge M giants to a control sample of local disk M giants in the Solar vicinity, we find the bulge stars are enhanced in alpha elements at the level of +0.3 dex relative to the Solar composition stars, consistent with other studies of bulge globular clusters and field stars. This small sample shows no dependence of spectral type on metallicity, nor is there any indication that the M giants are the evolved members of a subset of the bulge population endowed with special characteristics such as relative youth or high metallicity. We also find low 12C/13C < 10, confirming the prsence of extra-mixing processes during the red gaint phase of evolutionComment: 19 pages, 7 figures, accepted for publication in the Astrophysical Journa

    Beyond Freezing: Low Temperature Lipidic Cubic Phase As Biomimetic, Nanoconfining Matrix

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    Lipidic cubic phases (LCPs) are used in areas ranging from membrane biology to drug delivery. Because some membrane proteins are notoriously unstable at room temperature, and available LCPs undergo transformation to lamellar phases at low temperatures, the development of stable low-temperature LCPs for biophysical studies of membrane proteins is called for. A family of synthetic lipids with designed cyclopropyl modifications in the hydrophobic chains was synthesised in order to study the relationship between lipid molecular structure and mesophase behaviour. These lipids show a unique liquid-crystalline behaviour at low temperatures, enabling the use of LCP crystallisation in conditions never explored before.1 Please click Additional Files below to see the full abstract

    The intermediate-age globular cluster NGC 1783 in the Large Magellanic Cloud

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    We present Hubble Space Telescope ACS deep photometry of the intermediate-age globular cluster NGC 1783 in the Large Magellanic Cloud. By using this photometric dataset, we have determined the degree of ellipticity of the cluster (ϵ\epsilon=0.14±\pm0.03) and the radial density profile. This profile is well reproduced by a standard King model with an extended core (r_c=24.5'') and a low concentration (c=1.16), indicating that the cluster has not experienced the collapse of the core. We also derived the cluster age, by using the Pisa Evolutionary Library (PEL) isochrones, with three different amount of overshooting (namely, Λos\Lambda_{os}=0.0, 0.10 and 0.25). From the comparison of the observed Color-Magnitude Diagram (CMD) and Main Sequence (MS) Luminosity Function (LF) with the theoretical isochrones and LFs, we find that only models with the inclusion of some overshooting (Λos\Lambda_{os}=0.10-0.25) are able to reproduce the observables. By using the magnitude difference δVSGBHe−Cl=0.90\delta V_{SGB}^{He-Cl}=0.90 between the mean level of the He-clump and the flat region of the SGB, we derive an age τ\tau=1.4±\pm0.2 Gyr.Comment: Accepted to publication by A
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