911 research outputs found
Leptospira spp y leptospirosis humana
Resumen Introducción. La leptospirosis, enfermedad bacteriana zoonótica y emergente más importante en el mundo, es causada por las especies patógenas de Leptospira spp. Objetivo. Revisar información reciente sobre Leptospira spp. y leptospirosis humana con énfasis en América y Colombia. Metodología. Revisión de artículos indexados en PubMed, relacionados con la microbiología, epidemiología, presentación clínica en humanos, diagnostico, tratamiento y prevención de la enfermedad (vacunas). Resultados. Veinte especies de Leptospira spp han sido descritas; se ha determinado la secuencia del ADN genómico de algunas cepas patógenas, la función de la mayoría de los genes involucrados en su patogénesis permanece desconocida. La leptospirosis humana presenta un rango de síntomas que van desde una fiebre indiferenciada hasta una ictericia, hemorragia, fallas renales y pulmonares severas. La administración temprana e intravenosa de penicilina G es requerida para reducir las tasas de mortalidad, pero los antibióticos pueden no ser efectivos en la enfermedad pulmonar severa. En las Americas, las areas de alto riesgo son Brasil, Centro América y el Caribe. Pocos estudios han sido realizados en Colombia. La prueba serológica de oro, la microaglutinación tiene alta sensibilidad y especificidad cuando se usan baterías de serovariedades locales pero es serogrupo específica. Las vacunas generan respuestas específicas para la serovariedad usada, pero no previenen la infección o trasmisión. Conclusiones. Problemas en el diagnóstico de laboratorio de la leptospirosis conllevan a un sub-registro en el número de casos; altas tasas de mortalidad asociadas a fallas renal y pulmonar son resultado de las dificultades en el manejo de los casos
Searching for tidal tails around Centauri using RR Lyrae Stars
We present a survey for RR Lyrae stars in an area of 50 deg around the
globular cluster Centauri, aimed to detect debris material from the
alleged progenitor galaxy of the cluster. We detected 48 RR Lyrae stars of
which only 11 have been previously reported. Ten among the eleven previously
known stars were found inside the tidal radius of the cluster. The rest were
located outside the tidal radius up to distances of degrees from the
center of the cluster. Several of those stars are located at distances similar
to that of Centauri. We investigated the probability that those stars
may have been stripped off the cluster by studying their properties (mean
periods), calculating the expected halo/thick disk population of RR Lyrae stars
in this part of the sky, analyzing the radial velocity of a sub-sample of the
RR Lyrae stars, and finally, studying the probable orbits of this sub-sample
around the Galaxy. None of these investigations support the scenario that there
is significant tidal debris around Centauri, confirming previous
studies in the region. It is puzzling that tidal debris have been found
elsewhere but not near the cluster itself.Comment: 11 pages, 11 figures, Accepte
Hardy spaces for a class of singular domains
We set a framework for the study of Hardy spaces inherited by complements of analytic hypersurfaces in domains with a prior Hardy space structure. The inherited structure is a filtration, various aspects of which are studied in specific settings. For punctured planar domains, we prove a generalization of a famous rigidity lemma of Kerzman and Stein. A stabilization phenomenon is observed for egg domains. Finally, using proper holomorphic maps, we derive a filtration of Hardy spaces for certain power-generalized Hartogs triangles, although these domains fall outside the scope of the original framework
Searching for RR Lyrae stars in the Canis Major Overdensity
The Canis Major overdensity (CMa) was initially proposed to be the remnant of
a tidally disrupting dSph galaxy. Since its nature is still subject of debate,
the goal of the present work was to conduct a large-scale RR Lyrae survey in
CMa, in order to see if there is an overdensity of these stars. The survey
spans a total area of ~34 sq. deg. with observations in V and R filters, made
with the 1.0m Jurgen Stock Schmidt telescope at the National Astronomical
Observatory of Venezuela. Current results in a subregion, including
spectroscopic observations, show that the small number of RR Lyrae stars found
can be accounted for by the halo and thick disk components of our Galaxy.Comment: 2 pages, 1 figure, to appear in the proceedings of IAU Symposium
No241 "Stellar Populations as Building Blocks of Galaxies
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