105 research outputs found

    On the mathematical analysis of the limit case of a radiative—convective climate model

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    We study the limit case corresponding to a model introduced by G.L. Stenchikov and A. Robock for the evolution of the temperature of an atmospheric column in absence of humidity. The model envolves a degenerate noncoercive quasilinear equation. The diffusion coefficient depends of the atmospheric stability and vanishes on the stable regions. We show the existence and uniqueness of a suitable class of weak solutions and prove that the number of stable and unstable regions are nonincreasing in time

    Physical Properties, Star Formation, and Active Galactic Nucleus Activity in Balmer Break Galaxies at 0 < z < 1

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    We present a spectroscopic study with the derivation of the physical properties of 37 Balmer break galaxies, which have the necessary lines to locate them in star-forming-AGN diagnostic diagrams. These galaxies span a redshift range from 0.045 to 0.93 and are somewhat less massive than similar samples of previous works. The studied sample has multiwavelength photometric data coverage from the ultraviolet to MIR Spitzer bands. We investigate the connection between star formation and AGN activity via optical, mass-excitation (MEx) and MIR diagnostic diagrams. Through optical diagrams, 31 (84%) star-forming galaxies, 2 (5%) composite galaxies and 3 (8%) AGNs were classified, whereas from the MEx diagram only one galaxy was classified as AGN. A total of 19 galaxies have photometry available in all the IRAC/Spitzer bands. Of these, 3 AGN candidates were not classified as AGN in the optical diagrams, suggesting they are dusty/obscured AGNs, or that nuclear star formation has diluted their contributions. Furthermore, the relationship between SFR surface density (\Sigma_{SFR}) and stellar mass surface density per time unit (\Sigma_{M_{\ast}/\tau}) as a function of redshift was investigated using the [OII] \lambda3727, 3729, H\alpha \lambda6563 luminosities, which revealed that both quantities are larger for higher redshift galaxies. We also studied the SFR and SSFR versus stellar mass and color relations, with the more massive galaxies having higher SFR values but lower SSFR values than less massive galaxies. These results are consistent with previous ones showing that, at a given mass, high-redshift galaxies have on average larger SFR and SSFR values than low-redshift galaxies. Finally, bluer galaxies have larger SSFR values than redder galaxies and for a given color the SSFR is larger for higher redshift galaxies.Comment: preprint version, 36 pages, 17 figures, 3 tables, accepted for publication in the Astrophysical Journa

    Fungal microbiota from rain water and pathogenicity of Fusarium species isolated from atmospheric dust and rainfall dust

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    In order to determine the presence of Fusarium spp. in atmospheric dust and rainfall dust, samples were collected during September 2007, and July, August, and October 2008. The results reveal the prevalence of airborne Fusarium species coming from the atmosphere of the South East coast of Spain. Five different Fusarium species were isolated from the settling dust: Fusarium oxysporum, F. solani, F. equiseti, F. dimerum, and F. proliferatum. Moreover, rainwater samples were obtained during significant rainfall events in January and February 2009. Using the dilution-plate method, 12 fungal genera were identified from these rainwater samples. Specific analyses of the rainwater revealed the presence of three species of Fusarium: F. oxysporum, F. proliferatum and F. equiseti. A total of 57 isolates of Fusarium spp. obtained from both rainwater and atmospheric rainfall dust sampling were inoculated onto melon (Cucumis melo L.) cv. Piñonet and tomato (Lycopersicon esculentum Mill.) cv. San Pedro. These species were chosen because they are the main herbaceous crops in Almeria province. The results presented in this work indicate strongly that spores or propagules of Fusarium are able to cross the continental barrier carried by winds from the Sahara (Africa) to crop or coastal lands in Europe. Results show differences in the pathogenicity of the isolates tested. Both hosts showed root rot when inoculated with different species of Fusarium, although fresh weight measurements did not bring any information about the pathogenicity. The findings presented above are strong indications that long-distance transmission of Fusarium propagules may occur. Diseases caused by species of Fusarium are common in these areas. They were in the past, and are still today, a problem for greenhouses crops in Almería, and many species have been listed as pathogens on agricultural crops in this region. Saharan air masses dominate the Mediterranean regions. The evidence of long distance dispersal of Fusarium spp. by atmospheric dust and rainwater together with their proved pathogenicity must be taken into account in epidemiological studies

    A photometric and spectroscopic study of NSVS 14256825: the second sdOB+dM eclipsing binary

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    We present an analysis of UBVRC_{\rm C}IC_{\rm C}JH photometry and phase-resolved optical spectroscopy of NSVS 14256825, an HW Vir type binary. The members of this class consist of a hot subdwarf and a main-sequence low-mass star in a close orbit (Porb 0.1P_{\rm orb} ~ 0.1 d). Using the primary-eclipse timings, we refine the ephemeris for the system, which has an orbital period of 0.11037 d. From the spectroscopic data analysis, we derive the effective temperature, T1=40000±500T_1 = 40000 \pm 500 K, the surface gravity, logg1=5.50±0.05\log g_1 = 5.50\pm0.05, and the helium abundance, n(He)/n(H)=0.003±0.001n(\rm He)/n(\rm H)=0.003\pm0.001, for the hot component. Simultaneously modelling the photometric and spectroscopic data using the Wilson-Devinney code, we obtain the geometrical and physical parameters of NSVS 14256825. Using the fitted orbital inclination and mass ratio (i = 82\fdg5\pm0\fdg3 and q=M2/M1=0.260±0.012q = M_2/M_1 = 0.260\pm0.012, respectively), the components of the system have M1=0.419±0.070MM_1 = 0.419 \pm 0.070 M_{\odot}, R1=0.188±0.010RR_1 = 0.188 \pm 0.010 R_{\odot}, M2=0.109±0.023MM_2 = 0.109 \pm 0.023 M_{\odot}, and R2=0.162±0.008RR_2 = 0.162 \pm 0.008 R_{\odot}. From its spectral characteristics, the hot star is classified as an sdOB star.Comment: 8 pages, 7 figures, accepted for publication in MNRA

    Galaxies behind the Galactic plane: First results and perspectives from the VVV Survey

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    Vista Variables in The Via Lactea (VVV) is an ESO variability survey that is performing observations in near infrared bands (ZYJHKs) towards the Galactic bulge and part of the disk with the completeness limits at least 3 mag deeper than 2MASS. In the present work, we searched in the VVV survey data for background galaxies near the Galactic plane using ZYJHKs photometry that covers 1.636 square degrees. We identified 204 new galaxy candidates by analyzing colors, sizes, and visual inspection of multi-band (ZYJHKs) images. The galaxy candidates colors were also compared with the predicted ones by star counts models considering a more realistic extinction model at the same completeness limits observed by VVV. A comparison of the galaxy candidates with the expected one by Milennium simulations is also presented. Our results increase the number density of known galaxies behind the Milky Way by more than one order of magnitude. A catalog with galaxy properties including ellipticity, Petrosian radii and ZYJHKs magnitudes is provided, as well as comparisons of the results with other surveys of galaxies towards Galactic plane.Comment: 27 pages, 10 figures, 2 tables; in press at The Astronomical Journa

    Bad sleeping quality in patients receiving HAART

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    El manejo de un paciente infectado por el virus de inmunodefi ciencia humana (VIH) implica un enfoque multidisciplinario que incluya diversas esferas de la salud de la persona1. Sin embargo, en muchas oportunidades la evaluación se centra en marcadores meramente biológicos descuidando aspectos de índole psicológico y social que tendrían importante repercusión en la calidad de vida de estos pacientes. Dentro de ellos, las alteraciones del sueño (AS), son un factor a considerar, más aún cuando han demostrado tener un impacto negativo en la calidad de vida de las personas2, asimismo, un incremento de la probabilidad de desarrollo de diabetes mellitus, enfermedad cardiovascular y dolencias respiratorias.Revisión por pare

    The First Galaxy Cluster Discovered by the VISTA Variables in the Vía Láctea Survey

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    We report the first confirmed detection of the galaxy cluster VVV-J144321-611754 at very low latitudes (l = 315.°836, b = -1.°650) located in the tile d015 of the VISTA Variables in the Vía Láctea (VVV) survey. We defined the region of 30 ×30 arcmin 2 centered in the brightest galaxy finding 25 galaxies. For these objects, extinction-corrected median colors of (H-K s ) = 0.34 ± 0.05 mag, (J-H) = 0.57 ± 0.08 mag, and (J-K s ) = 0.87 ± 0.06 mag; R 1/2 = 1.59 ± 0.″16; C = 3.01 ± 0.08; and Sérsic index n = 4.63 ± 0.39 were estimated. They were visually confirmed showing characteristics of early-type galaxies in the near-IR images. An automatic clustering analysis performed in the whole tile found that the concentration of galaxies VVV-J144321-611754 is a real, compact concentration of early-type galaxies. Assuming a typical galaxy cluster with low X-ray luminosity, the photometric redshift of the brightest galaxy is z = 0.196 ± 0.025. Follow-up near-IR spectroscopy with FLAMINGOS-2 at the Gemini-South telescope revealed that the two brighter cluster galaxies have typical spectra of early-type galaxies and the estimated redshift for the brightest galaxy VVV-J144321.06-611753.9 is z = 0.234 ± 0.022 and that for VVV-J144319.02-611746.1 is z = 0.232 ± 0.019. Finally, these galaxies clearly follow the cluster red sequence in the rest-frame near-IR color-magnitude diagram with a slope similar to a galaxy cluster at a redshift of 0.2. These results are consistent with the presence of a bona fide galaxy cluster beyond the Milky Way disk.Fil: Baravalle, Laura Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Nilo Castellón, José Luis. Universidad de La Serena; ChileFil: Alonso, Maria Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Díaz Tello, J.. Pontificia Universidad Católica de Chile; Chile. Universidad Nacional Autónoma de México; MéxicoFil: Damke, G.. Universidad de La Serena; ChileFil: Valotto, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Cuevas Larenas, H.. Universidad de La Serena; ChileFil: Sánchez, Bruno Orlando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Ríos, M. de los. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Minniti, D.. Universidad Andrés Bello; ChileFil: Domínguez, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Gurovich, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Barbá, R.. Universidad de La Serena; ChileFil: Soto, M.. Universidad de Atacama; ChileFil: Castro, F. Milla. Universidad de La Serena; Chil

    Evaluación de la resistencia a Phytophthora capsici y Phytophthora nicotianae var. parasitica de tres portainjertos comerciales de pimiento

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    Los problemas que se plantean con Phytophthora capsici y Phytophthora nicotianae var. parasitica (Phytophthora parasitica) para su control, utilizando distintos procedimientos de desinfección del suelo, han motivado la evaluación de vías alternativas utilizando plantas injertadas sobre porta-injertos resistentes. Esta técnica goza de un éxito importante para el control de otros patógenos del suelo y es una técnica compatible con la producción ecológica. Por ejemplo, en el control del virus del cribado (MNSV) en melón y sandía o en el control de P. parasitica en tomate. Siguiendo esas orientaciones existen en el mercado, actualmente, patrones que se preconizan con resistencias a patógenos que, a veces, no están suficientemente evaluados. Este hecho ha motivado el trabajo que se resume en esta comunicación

    Reversal of economic fortunes: institutions and the changing ascendancy of Barcelona and Madrid as economic hubs

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    This paper looks at the divergent economic trajectories of Barcelona and Madrid since Spain's transition to democracy. It highlights how Barcelona, the city that was better positioned four decades ago to emerge as the main Spanish economic hub, has lost out to Madrid. We argue that the contrasting trajectories of the two cities have less to do with the pull of Madrid as the capital of Spain, with the development of new infrastructure in the country, or with agglomeration economies, and more with institutional factors. A growing societal divide in Barcelona along economic, social, and identity lines has led to a greater breakdown of trust and to the development of strong groups with limited capacity to bridge with one another than in Madrid. This has entailed the emergence of negative externalities that have limited the economic potential for growth in Barcelona and facilitated the rise of Madrid as the main economic hub within Spain

    Response to Comment on “Plant diversity increases with the strength of negative density dependence at the global scale”

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    Hülsmann and Hartig suggest that ecological mechanisms other than specialized natural enemies or intraspecific competition contribute to our estimates of conspecific negative density dependence (CNDD). To address their concern, we show that our results are not the result of a methodological artifact and present a null-model analysis that demonstrates that our original findings—(i) stronger CNDD at tropical relative to temperate latitudes and (ii) a latitudinal shift in the relationship between CNDD and species abundance—persist even after controlling for other processes that might influence spatial relationships between adults and recruits
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