418 research outputs found

    Influencia de la administración de parathormona, calcitonina y tiroxina sobre la excreción de calcio endógeno

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    The influence of seyeral hormonal factors on calcium, endogenous excretion was studied in adult rats. The injection of parathyroid hormone doesn't change the fecal endogenous calcium. It may be that the parathyroid hormone have a real effect over the intestinal absortion of calcium, effect, that in our experiments, would be masked by an increase in the calcitonine secretion. In the kidney, the parathyroid hormone causes an increase, of endogenous caldum excretion highly significative, which it would be possible the result of the raising of the calcemia. The administration of calcitonine or thyroxine produces an increase in the fecal and urinary excretion of endogenous calcium. Possibly, the calcitonine produces hypercalciurie and hypocalcemia acting directly upon the kidney and inhibiting the tubular reabsorption of calcium.Se estudia la influencia de varios factores hormonales sobre la excreción de calcio endógeno en ratas adultas de la cepa Nestlé. En nuestras condiciones experimentales la administración de parathormona no cambia la excreción fecal de calcio endógeno. Puede ser que la parathormona tenga un efecto real sobre la absorción intestinal de calcio, efecto que en nuestro caso quedaría enmascarado por un aumento en la secreción de calcitonina. A nivel renal la administración de parathormona produce un incremento estadísticamente significativo de la excreción de calcio endógeno, que podría ser el resultado de la elevación de la calcemia. La administración de calcitonina o de tiroxina dan lugar a un incremento en la excreción fecal y urinaria de calcio endógeno. Posiblemente la calcitonina produzca hipercalciuria e hipocalcemia actuando directamente a nivel renal e inhibiendo la reabsorción tubular de calcio

    The collapse of Io's primary atmosphere in Jupiter eclipse

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    Volcanic outgassing due to tidal heating is the ultimate source of a tenuous SO atmosphere around Jupiter's moon Io. The question of whether SO frost on the surface plays a part, and to what degree, in maintaining Io's atmosphere with the constant volcanic outgassing is still debated. It is believed that for a sublimation-supported atmosphere, the primary atmosphere should collapse during eclipses by Jupiter, as the SO vapor pressure is strongly coupled to the temperature of the ice on the surface. No direct observations of Io's atmosphere in eclipse have previously been possible, due to the simultaneous need for high spectral and time sensitivity, as well as a high signal-to-noise ratio. Here we present the first ever high-resolution spectra at 19 µm of Io's SO atmosphere in Jupiter eclipse from the Gemini telescope. The strongest atmospheric band depth is seen to dramatically decay from 2.5 ± (0.08)% before the eclipse to 0.18 ± (0.16)% after 40 min in eclipse. Further modeling indicates that the atmosphere has collapsed shortly after eclipse ingress, implying that the atmosphere of Io has a strong sublimation-controlled component. The atmospheric column density—from pre-eclipse to in-eclipse—drops by a factor of 5 ± 2.C.C.C.T. and J.R.S. at Southwest Research Institute were funded by NASA Outer Planets Research grant NNX14AC63G and Planetary Astronomy grant NNX11AD61G. M.A.L.V. was funded by the Spanish Ministerio de Economia y Competitividad and by FEDER funds under project ESP2015-65064-C2-1-P (MINECO/FEDER)Peer Reviewe

    Oral pathology in the Iberian Neanderthals

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    In 1994, a series of human bones was found at the Sidrón cave in Borines (Concejo de Piloña, Asturias), Spain. Since the investigators suspected that they were dealing with human remains from the Spanish Civil War (1936-1939), the bones were collected by the Civil Guard, but were not subjected to archeological scrutiny. The finding was reported then to the corresponding authorities, who had them sent to the Laboratory of Forensic Anthropology of the Forensic Institute of Madrid (Spain), where an anthropological study was undertaken. This revealed the extraordinary palaeoanthropological and palaeopathological interest of the remains. The specimen studied herein, a mandible catalogued as SDR 7-8 (SIDRON 7-8) by the Forensic Laboratory in Madrid (Spain) and belonging to Homo neanderthalensis, with an age of 90,000 to 40,000 years BCE, showed special characteristics of oral pathology, making it a specimen of great palaeodontological interest.Key words: Mandible, Neanderthal, oral pathology, Sidrón, Asturias

    Variability of the Martian thermosphere during eight Martian years as simulated by a ground-to-exosphere global circulation model

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    Using a ground-to-exosphere general circulation model for Mars we have simulated the variability of the dayside temperatures at the exobase during eight Martian years (MY, from MY24 to MY31, approximately from 1998 to 2013), taking into account the observed day-to-day solar and dust load variability. We show that the simulated temperatures are in good agreement with the exospheric temperatures derived from Precise Orbit Determination of Mars Global Surveyor. We then study the effects of the solar variability and of two planetary-encircling dust storms on the simulated temperatures. The seasonal effect produced by the large eccentricity of the Martian orbit translates in an aphelion-to-perihelion temperature contrast in every simulated year. However, the magnitude of this seasonal temperature variation is strongly affected by the solar conditions, ranging from 50 K for years corresponding to solar minimum conditions to almost 140 K during the last solar maximum. The 27 day solar rotation cycle is observed on the simulated temperatures at the exobase, with average amplitude of the temperature oscillation of 2.6 K but with a significant interannual variability. These two results highlight the importance of taking into account the solar variability when simulating the Martian upper atmosphere and likely have important implications concerning the atmospheric escape rate. We also show that the global dust storms in MY25 and MY28 have a significant effect on the simulated temperatures. In general, they increase the exospheric temperatures over the low latitude and midlatitude regions and decrease them in the polar regions.©2015. American Geophysical Union. All Rights Reserved.F.G.G. was partly funded by a CSIC JAE-Doc grant financed by the European Social Fund. F.G.G., M.-A.L.V., and M.G.C. thank the Spanish MICINN for funding support through the CONSOLIDER program ASTROMOLCSD2009-00038 and through projects AYA2011-23552/ESP and AYA2012-39691-C02-01. This work has also been partially funded by the ESA-CNES project Mars Climate Database and Physical Models.Peer Reviewe

    Desarrollo de un algoritmo de solución directa para el cálculo de distribuciones óptimas de cultivos bajo riego deficitario controlado

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    La adecuada gestión de un recurso natural cada vez más escaso, como es el agua, implica maximizar la eficiencia en su uso. Desde el punto de vista de una explotación agraria, es de la máxima importancia encontrar la distribución óptima de cultivos que maximice el margen bruto obtenido con el agua de riego disponible. Actualmente, los métodos de optimización disponibles para resolver este problema no lineal, recurren a métodos de optimización heurísticos de propósito general mucho más lentos y menos eficientes de lo que sería un algoritmo de optimización de solución directa, donde se conocen los mecanismos involucrados y las sinergias existentes entre los cultivos para la obtención de la solución óptima del problema. El objetivo del presente trabajo es desarrollar un algoritmo de solución directa capaz de determinar la distribución óptima de cultivos que sea compatible con el modelo MOPECO (Modelo de Optimización Económica del agua de riego). La solución óptima se consigue con sólo uno o dos cultivos, pero esta solución no es la más adecuada desde el punto de vista agronómico (p.e. rotación de cultivos, PAC, etc.), por lo que ha sido necesario adaptar el algoritmo desarrollado para manejar este tipo de situaciones. Para una hipotética explotación de 100 ha, considerando 10 cultivos diferentes y 11 escenarios de volumen de agua total disponible, se han comparado los resultados del algoritmo desarrollado con las soluciones ofrecidas por el software de optimización LINGO y los algoritmos genéticos. El algoritmo desarrollado consigue márgenes brutos un 0,5% inferiores a los de LINGO, y un 1,1% mayores que los algoritmos genéticos, reduciendo el tiempo de cálculo entre 50-100 y 2000 veces, respectivamente

    IAA : Información y actualidad astronómica (10)

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    Sumario : Investigación: Chorros relativistas en núcleos activos de galaxias.-- Materia oscura: a tientas por el Universo.-- Ventana Abierta: Físico teórico autónomo se ofrece para.-- Charlas con… Robert Haberle.-- Actualidad Científica: La búsqueda de las estrellas más viejas de la Galaxia.-- Un superbólido más brillante que la Luna llena surcó el cielo argelino.-- Actividades IAA.-- Agenda.Esta revista se publica con la ayuda de la Acción Especial DIF 2001-4284-E del Programa Nacional de Difusión de la Ciencia y la Tecnología, del Ministerio de Ciencia y TecnologíaN

    IAA : Información y actualidad astronómica (27)

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    Sumario : Sagitario A*: el agujero negro en el corazón de la Vía Láctea.-- ESPECIAL: Año Internacional de la Astronomía.-- HISTORIAS DE ASTRONOMÍA. Chandrasekhar y los agujeros negros.-- DECONSTRUCCIÓN Y otros ENSAYOS. Binarias de rayos X.-- EL “MOBY DICK” DE...Pedro Amado.-- ACTUALIDAD.-- ENTRE BASTIDORES.-- CIENCIA: PILARES E INCERTIDUMBRES. El tiempo.-- ACTIVIDADES IAA.N

    Updating known distribution models for forecasting climate change impact on endangered species

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    To plan endangered species conservation and to design adequate management programmes, it is necessary to predict their distributional response to climate change, especially under the current situation of rapid change. However, these predictions are customarily done by relating de novo the distribution of the species with climatic conditions with no regard of previously available knowledge about the factors affecting the species distribution. We propose to take advantage of known species distribution models, but proceeding to update them with the variables yielded by climatic models before projecting them to the future. To exemplify our proposal, the availability of suitable habitat across Spain for the endangered Bonelli’s Eagle (Aquila fasciata) was modelled by updating a pre-existing model based on current climate and topography to a combination of different general circulation models and Special Report on Emissions Scenarios. Our results suggested that the main threat for this endangered species would not be climate change, since all forecasting models show that its distribution will be maintained and increased in mainland Spain for all the XXI century. We remark on the importance of linking conservation biology with distribution modelling by updating existing models, frequently available for endangered species, considering all the known factors conditioning the species’ distribution, instead of building new models that are based on climate change variables only.Ministerio de Ciencia e Innovación and FEDER (project CGL2009-11316/BOS

    IAA : Información y actualidad astronómica (24)

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    Sumario : Máseres en el espacio.-- Venus Express.-- El complejo cinturón de asteroides.-- DECONSTRUCCIÓN Y otros ENSAYOS : Rotación diferencial y oscilaciones estelares.-- ACTUALIDAD.-- ENTRE BASTIDORES .-- HISTORIAS DE ASTRONOMÍA: El astrónomo de vista prodigiosa.-- CIENCIA: PILARES E INCERTIDUMBRES : Ondas gravitatorias.-- ACTIVIDADES IAA.Esta revista se publica con la ayuda FCT-08-0130 del Programa Nacional de Fomento de la Cultura Científica y Tecnológica 2008.N
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