13,945 research outputs found

    Relativistic quantum dynamics of scalar bosons under a full vector Coulomb interaction

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    The relativistic quantum dynamics of scalar bosons in the background of a full vector coupling (minimal plus nonminimal vector couplings) is explored in the context of the Duffin-Kemmer-Petiau formalism. The Coulomb phase shift is determined for a general mixing of couplings and it is shown that the space component of the nonminimal coupling is a {\it sine qua non} condition for the exact closed-form scattering amplitude. It follows that the Rutherford cross section vanishes in the absence of the time component of the minimal coupling. Bound-state solutions obtained from the poles of the partial scattering amplitude show that the time component of the minimal coupling plays an essential role. The bound-state solutions depend on the nonminimal coupling and the spectrum consists of particles or antiparticles depending on the sign of the time component of the minimal coupling without chance for pair production even in the presence of strong couplings. It is also shown that an accidental degeneracy appears for a particular mixing of couplings.Comment: 8 pages, 1 table. arXiv admin note: text overlap with arXiv:1403.603

    Phylogenetic inferences of Atelinae (Platyrrhini) based on multi-directional chromosome painting in Brachyteles arachnoides, Ateles paniscus paniscus and Ateles b. marginatus

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    We performed multi-directional chromosome painting in a comparative cytogenetic study of the three Atelinae species Brachyteles arachnoides, Ateles paniscus paniscus and Ateles belzebuth marginatus, in order to reconstruct phylogenetic relationships within this Platyrrhini subfamily. Comparative chromosome maps between these species were established by multi-color fluorescence in situ hybridization ( FISH) employing human, Saguinus oedipus and Lagothrix lagothricha chromosome-specific probes. The three species included in this study and four previously analyzed species from all four Atelinae genera were subjected to a phylogenetic analysis on the basis of a data matrix comprised of 82 discrete chromosome characters. The results confirmed that Atelinae represent a monophyletic clade with a putative ancestral karyotype of 2n = 62 chromosomes. Phylogenetic analysis revealed an evolutionary branching sequence \{Alouatta \{Brachyteles \{Lagothrix and Ateles\}\}\} in Atelinae and \{Ateles belzebuth marginatus \{Ateles paniscus paniscus \{Ateles belzebuth hybridus and Ateles geoffroyi\}\}\} in genus Ateles. The chromosomal data support a re-evaluation of the taxonomic status of Ateles b. hybridus. Copyright (C) 2005 S. Karger AG, Basel

    Effect of the thermal treatment on the chemical components, sorption, and shrinkage properties of Tectona grandis juvenile wood

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    The effect of thermal treatment on the chemical components, equilibrium moisture content (EMC), and shrinkage of teak juvenile wood was studied. Heartwood and sapwood samples were thermally-treated at 180 ºC and 200 ºC. Extractive, Klason lignin, holocellulose, and α-cellulose contents, as well as pH on untreated and thermally-treated woods, were determined. The EMC was reached at five relative humidity (RH) levels using saturated salt solutions: 86 % (KCl), 76 % (NaCl), 58 % (NaBr), 33 % (MgCl2), and 0 % (P2O5). Linear and volumetric shrinkages were calculated for all EMCs. The ratio of sorption (S), coefficient of shrinkage (h), and fiber saturation point (FSP) were also determined. Thermally-treated wood exhibited lower holocellulose and α-cellulose contents than untreated wood and increased acidity due to degradation of the hemicelluloses. The thermal treatment reduced the EMC of heartwood and sapwood. However, sapwood was more sensitive to RH variations than heartwood regardless of the treatment. Thermally-treated woods had higher hygroscopic and dimensional stabilities, and lower FSP than untreated wood. The thermal treatment did not affect radial shrinkage of the heartwood between 33 % and 86 % RH. Heartwood was more sensitive to the effect of the thermal treatment on shrinkage and degradation of cell wall polymers compared to sapwood

    Information processing among high-performance managers

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    O propósito deste estudo foi avaliar o processamento da informação de 43 gestores empresariais de desempenho superior. No seu enquadramento teórico recorremos a três modelos: a Teoria dos Papéis Gerenciais de Henry Mintzberg, a Teoria do Processamento da Informação e o Modelo de Processo de Resposta ao Rorschach de John Exner. A ava-liação dos sujeitos recorreu ao método do Rorschach. Os resultados deste estudo mos-traram que esses gerentes são capazes de recolher dados, avaliá-los e estabelecer ran-kings de maneira adequada. Ao mesmo tempo, verifica-se que são capazes de ser objeti-vos e precisos na avaliação dos problemas. Este estilo de processamento de informação possibilita uma interpretação do mundo a partir de um modo de processamento ou de um estilo cognitivo, próprio e característico.The purpose of this study was to evaluate the information processing of 43 business managers with a professional superior performance. The theoretical framework consid-ers three models: the Theory of Managerial Roles of Henry Mintzberg, the Theory of In-formation Processing, and Process Model Response to Rorschach by John Exner. The participants have been evaluated by Rorschach method. The results show that these managers are able to collect data, evaluate them and establish rankings properly. At same time they are capable of being objective and accurate in the problems assessment. This information processing style permits an interpretation of the world around on basis of a very personal and characteristic processing way or cognitive style.Fundação para a Ciência e a Tecnologia (FCT), no âmbito do Fundo de Apoio à Comunidade Científica - Edição de Publicações Periódicas de Natureza Científica

    Carcass quality of buffalo (Bubalus bubalis) finished in silvopastoral system in the Eastern Amazon, Brazil.

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    Avaliou-se a influência da dieta sobre a qualidade de carcaça de búfalos mestiços das raças Murrah e Mediterrâneo, alimentados com concentrado tradicional milho/soja ou resíduos agroindustriais tortas de coco e dendê. Os animais foram sacrificados em abatedouro comercial, e realizadas análises físicas e físico-químicas na carcaça, após 24 horas, e de cor e textura instrumentais no músculo Longissimus dorsi, após 48 horas de resfriamento. Os animais suplementados com a torta de dendê adquiriram melhor conformação de carcaça e acabamento de gordura, e observaram-se diferenças (P<0,05) no percentual de gordura na carcaça e na espessura de gordura de cobertura

    Comparison of methane emissions by cattle pastures in the Pantanal, between two seasons of the year.

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    This study was to evaluate the methane emissions in the Pantanal grasslands in the two main climatic periods of the year.(Embrapa Gado de Corte. Documentos, 216). Coordenador Roberto Giolo de Almeida. II SIGEE. Disponível em: . Acesso em: 30 nov. 2016
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