78 research outputs found

    Galactic Cosmic Rays from Superbubbles and the Abundances of Lithium, Beryllium, and Boron

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    In this article we study the galactic evolution of the LiBeB elements within the framework of a detailed model of the chemical evolution of the Galaxy that includes galactic cosmic ray nucleosynthesis by particles accelerated in superbubbles. The chemical composition of the superbubble consists of varying proportions of ISM and freshly supernova synthesized material. The observational trends of 6 LiBeB evolution are nicely reproduced by models in which GCR come from a mixture of 25% of supernova material with 75% of ISM, except for 6 Li, for which maybe an extra source is required at low metallicities. To account for 7 Li evolution several additional sources have been considered (neutrino-induced nucleosynthesis, nova outbursts, C-stars). The model fulfills the energetic requirements for GCR acceleration.Comment: 25 pages, 9 figures. Accepted for publication in the Astrophysical Journa

    Non-syndromic Hearing Impairment in a Hungarian Family with the m.7510T>C Mutation of Mitochondrial tRNA^^Ser(UCN)^^^ and Review of Published Cases

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    The m.7510T>C mitochondrial DNA (mtDNA) mutation is a tRNA(Ser(UCN)) alteration leading to matrilineal isolated hearing impairment. The current paper reviews the available reports on the m.7510T>C mtDNA mutation, with special attention to phenotypic variations and haplogroup background. A Hungarian family, the fourth family reported in the literature, is presented, in which analysis of three generations with bilateral isolated hearing loss revealed the m.7510T>C tRNA(Ser(UCN)) mutation in homoplasmic form in the affected members. Haplogroup analysis verified an unnamed subgroup of mitochondrial haplogroup H. Previously reported Spanish and North American Caucasian families belong to different subgroups of haplogroup H. Analyzing our biobank of Hungarian patients with sensorineural hearing loss, we did not detect this mutation in any other patient, nor was it found in Caucasian haplogroup H control samples. Comparing the cases reported so far, there is interfamilial variablity in the age of onset, accompanying symptoms, and haplogroup background. Our case adds further genetic evidence for the pathogenicity of the m.7510T>C mutation and underlines the need to include full mtDNA sequencing in the screening for unexplained hearing loss

    Cruising y e-citas: un nuevo contexto para los encuentros sexuales entre hombres jóvenes que tienen sexo con hombres

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    Resumen El objetivo de este artículo es el de explorar el papel que juega, en la actualidad, la irrupción de la mediación tecnológica de la información y la comunicación en la configuración de nuevos contextos para la relación sexual. En concreto, hemos explorado una práctica determinada, el cruising, entre hombres jóvenes que tienen sexo con hombres contactado a través de las e-citas. Se ha apostado por la metodología cualitativa con la intención de recopilar los discursos sobre sexualidad, riesgos y salud que se generan y construyen entre el grupo de iguales. Según extraemos de nuestro estudio, el nuevo marco que confiere esta tecnología estaría caracterizado por (a) una mayor accesibilidad a dichas prácticas, (b) una mayor difusión de estas, (c) una mayor inmediatez de acceso a las propuestas, (d) la anticipación de lo que será ofrecido en la cita, (e) acceso anónimo que permite propuestas más atrevidas y (f) una apertura mayor a la diversidad de usuarios. Todos estos elementos confluyen en un cuadro que nos lleva a considerar una organización social renovada de la práctica sexual

    Recuperação hidrofóbica de polipropileno tratado por VUV ou plasma

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    Tratamentos superficiais por plasma e ultravioleta de vácuo (VUV) foram utilizados para introduzir grupos funcionais contendo oxigênio em amostras de polipropileno, com objetivo de modificar sua molhabilidade. Análises por ATR-FTIR, AFM e ângulo de contato (AC) foram utilizadas para analisar as mudanças químicas e físicas na superfície do PP em função do tempo. Os resultados mostraram que as mudanças na molhabilidade das amostras tratadas por VUV ocorreram principalmente devido à alteração química da superfície. Nas amostras tratadas por plasma, o envelhecimento ocorreu mais rapidamente que as amostras tratadas por VUV. Para ambos os tratamentos, provavelmente ocorreu um rearranjo das cadeias durante o envelhecimento, além de uma possível reticulação da superfície na amostra tratada por VUV

    PIPELINE FFT FOR ULTRA WIDE BAND TECHNOLOGY

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