9,967 research outputs found

    On the nature of some SGRs and AXPs as rotation-powered neutron stars

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    We investigate the possibility that some SGRs/AXPs could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, LX/E˙rotL_X/\dot{E}_{\rm rot}, with respect to estimates based on fiducial NS parameters. We show that nine SGRs/AXPs can be described as canonical pulsars driven by the NS rotational energy, for LXL_X computed in the soft (2--10~keV) X-ray band. We compute the range of NS masses for which LX/E˙rot<1L_X/\dot{E}_{\rm rot}<1. We discuss the observed hard X-ray emission in three sources of the group of nine potentially rotation-powered NSs. This additional hard X-ray component dominates over the soft one leading to LX/E˙rot>1L_X/\dot{E}_{\rm rot}>1 in two of them. We show that 9 SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in the soft 2--10~keV band. Interestingly, four of them show radio emission and six have been associated with supernova remnants (including Swift J1834.9-0846 the first SGR observed with a surrounding wind nebula). These observations give additional support to our results of a natural explanation of these sources in terms of ordinary pulsars. Including the hard X-ray emission observed in three sources of the group of potential rotation-powered NSs, this number of sources with LX/E˙rot<1L_X/\dot{E}_{\rm rot}<1 becomes seven. It remains open to verification 1) the accuracy of the estimated distances and 2) the possible contribution of the associated supernova remnants to the hard X-ray emission.Comment: 11 pages, 14 figures, to appear in A&

    Gene identification for the cblD defect of vitamin B12 metabolism

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    Background Vitamin B12 (cobalamin) is an essential cofactor in several metabolic pathways. Intracellular conversion of cobalamin to its two coenzymes, adenosylcobalamin in mitochondria and methylcobalamin in the cytoplasm, is necessary for the homeostasis of methylmalonic acid and homocysteine. Nine defects of intracellular cobalamin metabolism have been defined by means of somatic complementation analysis. One of these defects, the cblD defect, can cause isolated methylmalonic aciduria, isolated homocystinuria, or both. Affected persons present with multisystem clinical abnormalities, including developmental, hematologic, neurologic, and metabolic findings. The gene responsible for the cblD defect has not been identified. Methods We studied seven patients with the cblD defect, and skin fibroblasts from each were investigated in cell culture. Microcell-mediated chromosome transfer and refined genetic mapping were used to localize the responsible gene. This gene was transfected into cblD fibroblasts to test for the rescue of adenosylcobalamin and methylcobalamin synthesis. Results The cblD gene was localized to human chromosome 2q23.2, and a candidate gene, designated MMADHC (methylmalonic aciduria, cblD type, and homocystinuria), was identified in this region. Transfection of wild-type MMADHC rescued the cellular phenotype, and the functional importance of mutant alleles was shown by means of transfection with mutant constructs. The predicted MMADHC protein has sequence homology with a bacterial ATP-binding cassette transporter and contains a putative cobalamin binding motif and a putative mitochondrial targeting sequence. Conclusions Mutations in a gene we designated MMADHC are responsible for the cblD defect in vitamin B12 metabolism. Various mutations are associated with each of the three biochemical phenotypes of the disorder

    Cadets’ Perceptions of Gymnastics Instruction for Officer Development

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    The United States Military Academy has offered gymnastics instruction since 1838. Gymnastics continues to be an integral component of the physical education curriculum. The purpose of this study was to investigate cadets\u27 perceptions of their experiences in a required gymnastics course using the critical incident technique. Students described experiences in the gymnastics class that they believed had a positive or negative influence on their development as cadets and future Army officers. Key elements of their responses were classified into 16 positively perceived and 11 negatively perceived categories. The top positive categories were confidence, encouragement, fear management, modeling, additional instruction, and teamwork. The top negative categories included lack of time, helplessness, discouragement, lack of relevance, unfair grading, and injur

    Estudo da aclimatação de lodo ativado com efluente “in natura” da industria de pescado

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    O presente trabalho estudou a adaptação e a atividade do lodo biológico procedente de um reator UASB de uma estação de tratamento de efluentes de uma indústria de processamento de pescado, para remoção biológica de nitrogênio em um Reator Batelada Seqüencial instrumentado em escala de bancada. A adaptação consistiu em aumento seqüencial da carga aplicada nas razões volumétricas efluente in natura : efluente sintético de 1:3,33; 1:2,5; 1:2,0; sendo a concentração inicial de inóculo empregada de 20 g SSV/L. Durante este período foram acompanhadas as variações de DQO, nitrato e amônia, onde se obteve uma remoção de até 80% da carga orgânica do efluente e de até 97% da matéria nitrogenada. O experimento com diluição de 1:3,33 foi realizado com adição de 0,5 % de sal para avaliar o efeito da salinidade, o qual também é considerado na análise dos resultados obtidos

    Fasceíte Necrotizante Causada por Photobacterium Damselae: o Primeiro Caso Descrito em Portugal

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    Necrotizing fasciitis is a severe soft tissue infection with a high mortality rate and therefore requires emergent surgical treatment. Several microorganisms can cause this infection, Photobacterium damselae being one of them, with only eight cases previously published in the literature. We report the first ever case of necrotizing fasciitis, caused by this microorganism, in Portugal. In this case report the patient survived after several debridement procedures and reconstruction of the upper limb with acellular dermal matrix and skin graft. A brief review of the Photobacterium damselae soft tissue infection reports as well as the clinical presentation, diagnosis, pathophysiology and treatment of necrotizing fasciitis can also be found in this paper.info:eu-repo/semantics/publishedVersio
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