77 research outputs found

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    Discovery of a weak magnetic field in the photosphere of the single giant Pollux

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    Aims: We observe the nearby, weakly-active single giant, Pollux, in order to directly study and infer the nature of its magnetic field. Methods: We used the new generation spectropolarimeters ESPaDOnS and NARVAL to observe and detect circular polarization within the photospheric absorption lines of Pollux. Our observations span 18 months from 2007-2009. We treated the spectropolarimetric data using the Least-Squares Deconvolution method to create high signal-to-noise ratio mean Stokes V profiles. We also measured the classical activity indicator S-index for the Ca H&K lines, and the stellar radial velocity (RV). Results: We have unambiguously detected a weak Stokes V signal in the spectral lines of Pollux, and measured the related surface-averaged longitudinal magnetic field Bl. The longitudinal field averaged over the span of the observations is below one gauss. Our data suggest variations of the longitudinal magnetic field, but no significant variation of the S-index. We observe variations of RV which are qualitatively consistent with the published ephemeris for a proposed exoplanet orbiting Pollux. The observed variations of Bl appear to mimic those of RV, but additional data for this relationship to be established. Using evolutionary models including the effects of rotation, we derive the mass of Pollux and we discuss its evolutionary status and the origin of its magnetic field. Conclusions: This work presents the first direct detection of the magnetic field of Pollux, and demonstrates that ESPaDOnS and NARVAL are capable of obtaining sub-G measurements of the surface-averaged longitudinal magnetic field of giant stars, and of directly studying the relationships between magnetic activity, stellar evolution and planet hosting of these stars.Comment: 8 pages, 6 figures, accepted for publication in Astronomy and Astrophysic

    The energy of waves in the photosphere and lower chromosphere: III. Inversion setup for Ca II H spectra in local thermal equilibrium

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    The Ca II H line is one of the strongest lines in the solar spectrum and provides continuous information on the solar atmosphere from the photosphere to the lower chromosphere. We describe an inversion approach that reproduces observed Ca II H spectra assuming LTE. We developed an inversion strategy based on the SIR code. The approach uses a two-step procedure with an archive of pre-calculated spectra to fit the line core and a subsequent iterative modification to improve the fit in the line wing. Simultaneous spectra in the 630nm range can optionally be used to fix the continuum temperature. The method retrieves 1D temperature stratifications neglecting lateral radiative transport. LOS velocities are included by an empirical approach. An archive of about 300.000 pre-calculated spectra is more than sufficient to reproduce the line core of observed Ca II H spectra both in quiet Sun and in active regions. The final thermodynamical stratifications match observed and best-fit spectra to a level of about 0.5 (1) % of Ic in the line wing (core). Inversion schemes based on pre-calculated spectra allow one a reliable and relatively fast retrieval of solar properties from observed chromospheric spectra. The approach can be easily extended to an 1D NLTE case by a simple exchange of the pre-calculated archive spectra.Comment: 15 pages, 15 figures, accepted for publication in A&A. The animation will only be provided in the A&A online sectio

    The energy of waves in the photosphere and lower chromosphere: IV. Inversion results of Ca II H spectra

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    Most static 1D atmosphere models in the quiet Sun predict a rise of the gas temperature at chromospheric layers, but numerical simulations only yield an increase in the brightness temperature. We investigate the thermal structure in the solar chromosphere as derived from an LTE inversion of Ca II H spectra in QS and active regions. We investigate the temperature stratifications on differences between magnetic and field-free regions in the QS, and between QS and ARs. We determine the energy content of individual calcium bright grains (BGs). The rms temperature fluctuations are below 100 K in the photosphere and 200-300 K in the chromosphere. The average temperature stratification in the QS does not exhibit a clear chromospheric temperature rise, opposite to the AR case. We find an energy content of about 7*10E18 J for BGs that repeat with a cadence of about 160 secs. The precursors of BGs have a vertical extent of about 200 km and a horizontal extent of about 1 Mm. The comparison of observed with synthetic NLTE profiles confirms that the solar chromosphere in the QS oscillates between an atmosphere in radiative equilibrium and one with a moderate chromospheric temperature rise. Two-dimensional x-z temperature maps exhibit nearly horizontal canopy-like structures with a few Mm extent around photospheric magnetic field concentrations at a height of about 600 km. The large difference between QS regions and ARs, and the better match of AR and non-LTE reference spectra suggest that magnetic heating processes are more important than commonly assumed. The temperature fluctuations in QS derived by the LTE inversion do not suffice on average to maintain a stationary chromospheric temperature rise. The spatially and vertically resolved information on the temperature structure allows one to investigate in detail the topology and evolution of the thermal structure in the lower solar atmosphere.Comment: 16 pages, 16 figures + 1 page Appendix, accepted by A&

    Atención Primaria y Trastornos Mentales y de l Comportamiento: una mirada exploratoria

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    Objetivo: Identificar la prevalencia de los problemas de comportamiento y salud mental que se relacionan con el primer nivel de atención a partir del análisis de las estadísticas de mortalidad a nivel nacional y en la provincia de Córdoba. Metodología: La fuente analizada fue la Base de Datos de Mortalidad 2005 y 2006 del Ministerio de Salud de la Nación. Se calcularon Tasas de Mortalidad Bruta (TMB) y Específica (TME) según sexo, edad y causa por Trastornos Mentales y de Comportamiento (TMyC), Mortalidad Proporcional (MP) y la razón de tasas para país y provincia de Córdoba. Softwares SPSS e InfoStat. Resultados: En el año 2005, la TMB fue similar entre país y provincia de Córdoba, mientras que las TME por causa y por sexo fueron inferiores en Córdoba. Los TMyC representaron el 0,74% de MP en Argentina, valores similares se registraron en 2006. Entre las muertes por TMyC, los Trastornos Mentales Orgánicos (TMO) y Trastornos Mentales y del Comportamiento debido al Uso de Alcohol (TMA), ocasionaron el 96% de las muertes registradas. Las muertes por TMO se acumulan a partir de los 60 años y las muertes por TMA se expresan como causa de muerte a partir de los 30 años. Las mujeres presentan una mayor incidencia en los TMO y los varones en los TMA. En la provincia de Córdoba se observaron valores similares a los registrados en el total del país. Conclusión: La prevalencia de los TMyC observados en los registros de estadísticas vitales de Argentina y provincia de Córdoba se relacionan a patologías que están incluidas como necesidades en el primer nivel de atención

    The Seventh Data Release of the Sloan Digital Sky Survey

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    This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11663 deg^2 of imaging data, with most of the roughly 2000 deg^2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry over 250 deg^2 along the Celestial Equator in the Southern Galactic Cap. A coaddition of these data goes roughly two magnitudes fainter than the main survey. The spectroscopy is now complete over a contiguous area of 7500 deg^2 in the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930,000 galaxies, 120,000 quasars, and 460,000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog (UCAC-2), reducing the rms statistical errors at the bright end to 45 milli-arcseconds per coordinate. A systematic error in bright galaxy photometr is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat-fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities. (Abridged)Comment: 20 pages, 10 embedded figures. Accepted to ApJS after minor correction

    Chemical Tagging in the Sdss-Iii/Apogee Survey: New Identifications of Halo Stars with Globular Cluster Origins

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    We present new identifications of five red giant stars in the Galactic halo with chemical abundance patterns that indicate they originally formed in globular clusters. Using data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) Survey available through Sloan Digital Sky Survey (SDSS) Data Release 12, we first identify likely halo giants, and then search those for the well-known chemical tags associated with globular clusters, specifically enrichment in nitrogen and aluminum. We find that 2% of the halo giants in our sample have this chemical signature, in agreement with previous results. Following the interpretation in our previous work on this topic, this would imply that at least 13% of halo stars originally formed in globular clusters. Recent developments in the theoretical understanding of globular cluster formation raise questions about that interpretation, and we concede the possibility that these migrants represent a small fraction of the halo field. There are roughly as many stars with the chemical tags of globular clusters in the halo field as there are in globular clusters, whether or not they are accompanied by a much larger chemically untaggable population of former globular cluster stars

    Genomic Characterization of Host Factors Related to SARS-CoV-2 Infection in People with Dementia and Control Populations: The GR@ACE/DEGESCO Study

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    Emerging studies have suggested several chromosomal regions as potential host genetic factors involved in the susceptibility to SARS-CoV-2 infection and disease outcome. We nested a COVID-19 genome-wide association study using the GR@ACE/DEGESCO study, searching for susceptibility factors associated with COVID-19 disease. To this end, we compared 221 COVID-19 confirmed cases with 17,035 individuals in whom the COVID-19 disease status was unknown. Then, we performed a meta-analysis with the publicly available data from the COVID-19 Host Genetics Initiative. Because the APOE locus has been suggested as a potential modifier of COVID-19 disease, we added sensitivity analyses stratifying by dementia status or by disease severity. We confirmed the existence of the 3p21.31 region (LZTFL1, SLC6A20) implicated in the susceptibility to SARS-CoV-2 infection and TYK2 gene might be involved in COVID-19 severity. Nevertheless, no statistically significant association was observed in the COVID-19 fatal outcome or in the stratified analyses (dementia-only and non-dementia strata) for the APOE locus not supporting its involvement in SARS-CoV-2 pathobiology or COVID-19 prognosis

    Recommendations for dental care in a situation of SARS-COV-2 pandemic and post-pandemic

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    La Odontología es una de las cinco profesiones más expuestas a contraer COVID-19, debido a la exposición -durante las actividades clínicas-al contacto con sangre, saliva, aerosoles, manipulación de sustancias potencialmente nocivas. El conocimiento de los riesgos propios de su entorno tiene como objetivo último evitar que los odontólogos y las personas vinculadas a la práctica profesional provoquen -por desconocimiento, inobservancia o falta de apropiación de los saberes-contagios y/o impactos desfavorables para ellos y el ambiente. Al minimizar el riesgo y la posibilidad de infecciones cruzadas se evitarán mayores contagios, en el contexto actual, sin desatender las emergencias odontológicas.publishedVersionFil: Allende Posse, María. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Arévalo, Paola. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Bojanich, Alejandra. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Bono, A. Colegio Odontológico de la Provincia de Córdoba; Argentina.Fil: Busleiman, Federico. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Castillo, Beatriz. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Castillo, Graciela. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Castillo, María Cristina. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Ermoli, J. Colegio Odontológico de la Provincia de Córdoba; Argentina.Fil: Flores, N. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Gigena, Pablo. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Girardi, Mónica. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Gutvay, Ada. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Herrera, Analía. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Huespe Rico, Verónica. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Irazuzta, María Laura. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Martínez, Dora. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Moriconi, E. Provincia de Córdoba. Ministerio de Ciencia y Tecnología; Argentina.Fil: Pereyra, María Eugenia. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Priotto, Elba. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Raya Tonetti, G. Provincia de Córdoba. Ministerio de Ciencia y Tecnología; Argentina.Fil: Rezzónico, M. S. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Scatena, Gabriela. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Vera, Mónica. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina.Fil: Zorrilla, Inés. Universidad Nacional de Córdoba. Facultad de Odontología. Equipo de Investigación en Higiene y Bioseguridad y Centro de Bioseguridad; Argentina
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