2,995 research outputs found

    Gravitino Dark Matter and Neutrino Masses in Partial Split Supersymmetry

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    Partial Split Supersymmetry with bilinear R-parity violation allows to reproduce all neutrino mass and mixing parameters. The viable dark matter candidate in this model is the gravitino. We study the hypothesis that both possibilities are true: Partial Split Supersymmetry explains neutrino physics and that dark matter is actually composed of gravitinos. Since the gravitino has a small but non-zero decay probability, its decay products could be observed in astrophysical experiments. Combining bounds from astrophysical photon spectra with the bounds coming from the mass matrix in the neutrino sector we derive a stringent upper limit for the allowed gravitino mass. This mass limit is in good agreement with the results of direct dark matter searches.Comment: 22 pages, 3 figure

    Geothermal Energy as an Alternative to Reduce Atmospheric Emissions and Provide Green Energy

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    Recently, there has been a worldwide rise of concern regarding the increasing emissions of air pollutants and global climate change. In contrast, there are also concerns about the growing energy consumption and how to guarantee its supply. Renewable energies can help minimize the use of fossil fuels, this being a high priority on the political agenda of countries around the world. Within renewable energies, geothermal energy is one of the oldest and most well-known sources of energy to generate electricity. Its use started in 1904 in Italy, but it needs a high initial investment. Depending on the geothermal reservoir, fluids drawn from the deep Earth could liberate a mixture of gases such as carbon dioxide, hydrogen sulfide, methane, and ammonia. The aim of this work is to compare gas emission of renewable, clean, and conventional sources of energy to be able to elucidate if geothermal energy could be a suitable green energy to minimize gas emissions to the atmosphere

    Effects of variable and constant temperatures on the embryonic development and survival of a new grape pest, xylotrechus arvicola (Coleoptera: Cerambycidae)

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    Xylotrechus arvicola Olivier (Coleoptera: Cerambycidae) has become a new expanding pest in grape (Vitis spp.) crops. To better improve control tactics, the consequences of 11 constant (12, 15, 18, 21, 24, 27, 30, 32, 34, 35 and 36°) and nine variable temperatures (with equal mean temperatures at each of the nine constant rates ranging from 15 to 35°) on survival and embryonic development were studied. The eggs were able to complete development at constant temperatures between 15 and 35°, with mortality rates at the extremes of the range of two and 81.5%, respectively. Using variable temperatures a mortality rate of 38.9% at a mean temperature of 15° and 99% at 35° was observed. The range of time for embryonic development was 29.5 d at 15° to 6 d at 32° at constant temperatures, and from 29.6 d at 15° to 7.2 d at 32° at variable temperatures. The goodness-of-fit of different development models was evaluated for the relationship between the development rate and temperature. The models that gave the best fit were the Logan type III for constant temperatures and The Briare for variable temperatures. Optimum temperatures were estimated to be from 31.7 to 32.9°. The models that best described embryo development under natural field conditions were the Logan type III model for constant temperatures (98.7% adjustment) and The Lactin model for variable temperatures (99.2% adjustment). Nonlinear models predicted faster development at constant temperatures and slower development at variable ones when compared with real field development, whereas the linear model always predicted faster development than what actually took place. © 2011 Entomological Society of America.The Spanish Institute for Food and Agricultural Sciences and Technologies (INIA) funded this research, project no. RTA04-117-C2.Peer Reviewe

    Climate and hydrological variability: the catchment filtering role

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    Abstract. Measuring the impact of climate change on flood frequency is a complex and controversial task. Identifying hydrological changes is difficult given the factors, other than climate variability, which lead to significant variations in runoff series. The catchment filtering role is often overlooked and thus may hinder the correct identification of climate variability signatures on hydrological processes. Does climate variability necessarily imply hydrological variability? This research aims to analytically derive the flood frequency distribution based on realistic hypotheses about the rainfall process and the rainfall–runoff transformation. The annual maximum peak flow probability distribution is analytically derived to quantify the filtering effect of the rainfall–runoff process on climate change. A sensitivity analysis is performed according to typical semi-arid Mediterranean climatic and hydrological conditions, assuming a simple but common scheme for the rainfall–runoff transformation in small-size ungauged catchments, i.e. the CN-SCS model. Variability in annual maximum peak flows and its statistical significance are analysed when changes in the climatic input are introduced. Results show that depending on changes in the annual number of rainfall events, the catchment filtering role is particularly significant, especially when the event rainfall volume distribution is not strongly skewed. Results largely depend on the return period: for large return periods, peak flow variability is significantly affected by the climatic input, while for lower return periods, infiltration processes smooth out the impact of climate change

    Decoupling of defect and short-range order contributions to resistivity recovery measurements in binary alloys

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    © 2014 American Physical Society. We report a new and improved approach that uses low-temperature resistivity recovery measurements to study the defect kinetics in metallic binary alloys. This method is able to decouple the effect related to the irradiation defect contribution to the resistivity from that of the short-range order, which is enhanced by the free migration of defects. This approach can provide reliable experimental data which are more suitable for comparisons with current computational models. Furthermore, the difference in this method with respect to the classical one is that our method gives information concerning the role of vacancies and interstitials on short-range order. The method is applied to a model alloy Fe-5%Cr, of interest for fusion applications, where short-range order effects have been previously found to play a role.Peer Reviewe

    Engineered microenvironments for synergistic VEGF - integrin signalling during vascularization

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    We have engineered polymer-based microenvironments that promote vasculogenesis both in vitro and in vivo through synergistic integrin-growth factor receptor signalling. Poly(ethyl acrylate) (PEA) triggers spontaneous organization of fibronectin (FN) into nanonetworks which provide availability of critical binding domains. Importantly, the growth factor binding (FNIII12-14) and integrin binding (FNIII9-10) regions are simultaneously available on FN fibrils assembled on PEA. This material platform promotes synergistic integrin/VEGF signalling which is highly effective for vascularization events in vitro with low concentrations of VEGF. VEGF specifically binds to FN fibrils on PEA compared to control polymers (poly(methyl acrylate), PMA) where FN remains in a globular conformation and integrin/GF binding domains are not simultaneously available. The vasculogenic response of human endothelial cells seeded on these synergistic interfaces (VEGF bound to FN assembled on PEA) was significantly improved compared to soluble administration of VEGF at higher doses. Early onset of VEGF signalling (PLCγ1 phosphorylation) and both integrin and VEGF signalling (ERK1/2 phosphorylation) were increased only when VEGF was bound to FN nanonetworks on PEA, while soluble VEGF did not influence early signalling. Experiments with mutant FN molecules with impaired integrin binding site (FN-RGE) confirmed the role of the integrin binding site of FN on the vasculogenic response via combined integrin/VEGF signalling. In vivo experiments using 3D scaffolds coated with FN and VEGF implanted in the murine fat pad demonstrated pro-vascularization signalling by enhanced formation of new tissue inside scaffold pores. PEA-driven organization of FN promotes efficient presentation of VEGF to promote vascularization in regenerative medicine applications

    La investigación sobre análisis de contenido y los lenguajes documentales en las publicaciones periódicas españolas de información y documentación (1982-1984)

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    Analysis of the bibliographic production on Content Analysis and Documentary Languages in Spain from 1982 to 1994, based on the articles published in seven spanish journals devoted to Library and Information Science subjects. The distribution of the papers by journals, years, number of authors, subjects, places and research centers is studied, with the following results: a) the most productive period is 1988-1990; b) Madrid and Barcelona, followed by Granada, are the most important centers of research; c) the majority of the papers are written by two or more authors, and they are only sporadic contributions; and d) the UDC and thesauri are by far the most researched subjects, followed only by abstracting. It may be concluded that neither content analysis nor indexing and classifying are important research topics in Spain compared with other traditional LIS research fields. Excluding papers from CINDOC (Madrid) and those of a very small group of productive individuals, a lack of well-grounded research lines and groups is evident. So, establishing lasting research groups, promoting periodical discussion meetings and, perhaps, a journal devoted specifically to these subjects is highly recommended. FinalIy, the bibliography resulting from the research project is appended in an annex.<br><br>Se analiza la producción bibliográfica sobre análisis de contenido y lenguajes documentales llevada a cabo en España entre 1982 y 1994 a partir de los artículos publicados en siete revistas españolas de información y documentación. Se estudia su distribución por revistas, años, número de autores por artículo, temas, lugares y centros de investigación, con los siguientes resultados: a) la producción alcanza sus cotas máximas entre 1988 Y 1990; b) Madrid y Barcelona, seguidos a cierta distancia por Granada, centralizan casi toda la producción; c) la mayor parte de los artículos son trabajos en colaboración, y tienen carácter esporádico; y d) la CDU y los tesauros son, con mucho, los temas más tratados, seguidos a gran distancia por los resúmenes. En definitiva, ni el análisis de contenido ni los lenguajes documentales son objeto de especial atención en las publicaciones seleccionadas. Con la excepción de la labor de los equipos de trabajo del CINDOC y de algunas personalidades individuales de gran relevancia, se echa de menos la existencia de líneas de investigación consolidadas. Por todo ello, se encarece la formación de equipos de investigación estables, la promoción de foros de discusión permanentes y, quizá, la aparición de alguna publicación periódica de carácter especializado que promocione y canalice la investigación en el campo. Finalmente, se adjunta en apéndice un anexo bibliográfico completo

    Meconio y exposición prenatal a neurotóxicos

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    6 pages, 1 figures, 2 tables.[ESP] Introducción. La ubicuidad con la que se encuentran la mayoría de las substancias neurotóxicas en el medio ambiente implica a los pediatras en la necesidad de desarrollar métodos para medir la magnitud de la exposición durante los periodos vulnerables del desarrollo. Una forma útil de abordar este problema consiste en analizar muestras biológicas que acumulen las substancias neurotóxicas o sus metabolitos durante el periodo fetal.Método. Revisión bibliográfica sistemática de los últimos 20 años obtenida principalmente de Medline; Science Citation Index y Embase sobre los estudios con meconio como matriz de exposición prenatal a substancias neurotóxicas. El perfil de búsqueda utilizado fue: meconium, prenatal exposure, biological markers, matrices, environmental pollutants, nervous system poisonings, neurotoxicity sindromes. Hemos seleccionado los trabajos más importantes y de sus referencias se han obtenido los más relevantes de los años previos a la búsqueda.Resultados. Tradicionalmente, los esfuerzos para determinar la exposición fetal se han centrado en el análisis de sangre de cordón u orina de la madre o el neonato. El meconio es fácilmente disponible, es inerte, acumula los neurotóxicos y/o sus metabolitos desde la semana 12 de gestación donde quedan “fosilizados” hasta el nacimiento. Puede constituir un instrumento muy importante para investigar la exposición fetal a los distintos contaminantes ambientales y en particular a neurotóxicos.Conclusiones. Las exposiciones fetales a los distintos neurotóxicos estudiados a través de sangre materna, de cordón, pelo, uña, placenta y orina parecen ser menos predictivas sobre los efectos neurológicos que las mediciones de los mismos realizadas en meconio. Son necesarios más estudios en este campo.Implementar y desarrollar la medida en meconio de una amplia gama de sustancias neurotóxicas ayudará en la práctica pediátrica a una intervención e identificación temprana mostrando las exposiciones que puedan provocar daño y facilitando el desarrollo de medidas preventivas y rehabilitadoras.[ENG] Brackground. The environmental ubiquity of most neurotoxicants implies the pediatricians in the development of methods for exposure measurement during the vulnerable periods of development. The analysis of biological samples able to accumulate the neurotoxicant substances or its metabolites during the fetal period is a useful approach to fulfil this objective.Material and methods. A systematic literature review of the last 20 years in Medline, Science Citation Index and Embase on the studies with meconium like womb of prenatal exposure to neurotoxicants has been undertaken. The search profile was: “meconium”, “prenatal exposure”, “biological markers”, “matrices”, “environmental pollutants”, “nervous system poisonings”, “neurotoxicity sindromes”. We selected the most relevant articles and retrieved more from their references.Results. Traditionally, the efforts to determine the fetal exposure have been centered in the analysis of cord blood, urinates of the mother or of the neonato. Meconium is easily available, inert, accumulates the neurotoxicants and/or its metabolitos from week 12 of gestation where they are "fossilized" until the birth. It can constitute a very important instrument for the investigation of the fetal exposure to the different environmental pollutants and in particular to neurotoxicants.Conclusions. Foetal exposure to different neurotoxicants monitored from maternal blood, cord blood, hair, fingernail, placenta and urinates seem to be less predictive for neurological effects than meconium. However, more studies are needed to confirm this hypothesis.Implementation and measurement in meconium of a wide range of neurotoxic substances will be of help in the pediatric practice for intervention and early identification as it will reveal harmful exposures and facilitate the implementation of preventive measures.Los autores quieren expresar su agradecimiento a los miembros de la red de Investigación Colaborativa INMA, y en especial a Amparo Quiles Latorre, Elena Romero Aliaga y Sandra Pérez Aliaga, por su apoyo y colaboración en la realización del trabajo de campo; al equipo de enfermería de la 7ª, 8ª y 9ª de la maternidad del Hospital Materno-Infantil Universitario La Fe y a los recién nacidos y sus felices padres que con su colaboración y entusiasmo hacen posible llevar a término estos estudios.Peer reviewe
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