760 resultados para Positron annihilation


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Using data corresponding to an integrated luminosity of 1.3fb -1, we observe a narrow mass state decaying into Υ(1S)+γ, where the Υ(1S) meson is detected by its decay into a pair of oppositely charged muons, and the photon is identified through its conversion into an electron-positron pair. The significance of this observation is 5.6 standard deviations. The mass of the state is centered at 10.551±0.014(stat) ±0.017(syst)GeV/c2, which is consistent with that of the state recently observed by the ATLAS Collaboration. © 2012 American Physical Society.

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The degradation phenomena of ZnO and SnO2-based varistors were investigated for two different degradation methods: DC voltage at increased temperature and degradation with 8/20 μs pulsed currents (lightning type). Electrostatic force microscopy (EFM) was used to analyze the surface charge accumulated at grain-boundary regions before and after degradation. Before the degradation process, 85% of the barriers are active in the SnO2 system, while the ZnO system presents only 30% effective barriers. Both systems showed changes in the electrical behavior when degraded with pulses. In the case of the ZnO system, the behavior after pulse degradation was essentially ohmic due to the destruction of barriers (about 99% of the interfaces are conductive). After the degradation with 8/20 μs pulsed currents, the SnO2 system still presents nonohmic behavior with a significant decrease in the quantity of effective barriers (from 85% to 5%). However, when the degradation is accomplished with continuous current, the SnO2 system exhibits minimum variation, while the ZnO system degrades from 30% to 5%. This result indicates the existence of metastable defects of low concentration and/or low diffusion in the SnO2 system. High energy is necessary to degrade the barriers due to defect annihilation in the SnO2 system. © 2013 The American Ceramic Society.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Letras - IBILCE

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Pós-graduação em Física - IFT

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A ação política e a aparência como espaço de protagonismo e de fidedignidade da realidade são temas que perpassam o pensamento de Hannah Arendt. Seu pensamento é marcado pela ruptura provocada pelo totalitarismo e por sua busca incessante da percepção da realidade e de sua reconstrução. Procuro neste trabalho abordar essa ruptura e com ela as problemáticas em torno da ação política e da aparência em um espaço de comparticipação de atos e palavras. Começo pela ação política, sua definição e características que a tornam um conceito central não só para a política mas para a existência de um espaço que garanta a realidade do nosso mundo: a aparência. Este espaço é abordado num segundo momento, suas problemáticas também são abordadas pela visão de alguns comentadores. O totalitarismo, abordado no terceiro capítulo, representa exatamente a ameaça a este espaço e ação, pois pretende destituir o homem de seu lugar no mundo. O totalitarismo é um projeto de construção de um mundo fictício que não aceita rivalizar com a realidade do nosso mundo. A relação entre as obras Origens do Totalitarismo (2006) e A Condição Humana (2005a) torna-se clara quando notamos que os elementos principais que constituem a condição humana são negados pelos elementos que formam o domínio totalitário. Para atingir o objetivo deste trabalho recorri às seguintes obras de Hannah Arendt: A Condição Humana (2005a), Entre o Passado e o Futuro (2005b), ¿Qué es política? (1997), A Vida do Espírito (2000) e Origens do Totalitarismo (2006). Procuro realizar uma exposição da temática da ação e da aparência por estas obras, além de lançar mão de comentadores e críticos de Arendt. O presente trabalho procura explorar os conceitos de aparência e ação, desenvolvendo suas problemáticas e situando-as diante do quadro apresentado pelo totalitarismo de aniquilação da espontaneidade e uniformização das massas.

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O tratamento dado pelos manuais à questão do método torna ausentes caracterizações de natureza ontológica, gnoseológica, epistemológica e antropológica. Em concreto, isso significa um esvaziamento da Sociologia como empreendimento (científico) total. É algo cujo sinal mais evidente é dado pela redução da ciência ao método. Rigorosamente, tal redução implica uma sobrevaloração do método e acarreta uma verdadeira desvaloração da Sociologia como investimento com intencionalidade científica.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Cannot the education reach the universality? Is the universality the annihilation of the individual? Can the individual have his identity preserved as such in the State? Those questions are answered with the attention returned and led to the education. To Hegel the education universalizes the individual insofar as it introduces him into the life of the State in which the subjectivity and individuality are known in fact, preserved and promoted. In the Elements of the Philosophy of Right, Hegel deals with the realization of freedom in the institution of State and identifies it with the realization of freedom. The aim here is to reflect upon the Hegelian comprehension of State towards education, its meaning, signification to the life of the State and its possible repercussions regarding the figures of the subject and individual also nowadays. To Hegel the education supports the State as such because it is the process of the Sate’s awareness along its formation as a living organism. A State that knows itself is a State that is known by its members who do not reach neither the State’s awareness nor themselves’ without the relation that gathers them together as the substantial universality. The education is the means that brings the individuals to the life of the State. Bringing the individual to the life in the State, the education reveals the individual to himself as well as to his true nature, that is, a being in relation to others who are not but himself. The knowledge of oneself in the education happens also through its formalization regarding the specific contents developed and accumulated throughout the history. Here comes the figure of the formal educator through whom the State aims its process of formation. This way Hegel confirms that nobody learns alone and that the universal is precisely this relation.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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(Photo)electrochemical experiments on pyrite electrodes in acetic acid-acetate buffer (pH = 4.5) are conducted to clarify the main oxidation reactions and the nature of the products. Electrochemical reactions in the -0.40 to 1.25 V (SHE) potential range are studied, and the production of iron (III) polysulfide from anodically formed iron oxides and polysulfides is discussed. Charges experimentally obtained are considered for the estimation of the most likely stoichiometry of the metallic polysulfide. The photoselectivity of the pyrite corrosion process indicates that the oxidation reactions of Fe2+ and S-2(2-) an not consecutive. The changes in stoichiometry and/or annihilation of crystalline structure defects are responsible for the observed photosensitivity of pyrite. A description of light effects on the interfacial behaviour and stability of pyrite is presented in terms of conduction and valence band energies, and thermodynamic potentials. (C) 2001 Elsevier Science B.V. All rights reserved.

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Since the beginning of life in society, the human being has sought sources of energy that can be used continuously, or stored to be consumed in times of need. The various energy generation processes has enabled the human race for the implementation of many activities ranging from food preparation, handling of large industries and even the possibility of total annihilation by the availability of powerful nuclear weapons. In Brazil, whereupon the various deleterious aspects and especially the finite resources used on a large scale for the energy conservation, there is a huge devotion of society referred to the prospects for alternatives to the use of energy in local, regional and global, but overall, as it wouldn’t be different, the main factors in this scenario are economic. The fact that the unused potential of a region in the use of alternative sources of energy leads to a larger socio-environmental prejudice generalized to all. The purpose of this project is targeted for a comprehensive, systemic and integrated discussion about some of the main alternative energy sources, associated with technical procedures related to them, to contribute to a better and effective use of natural resources available in each region of the country, in order to minimize the impacts on the environment in which they are inserted.

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In Heracles Mainomenos, by Euripides, the hero is submited to the ultimate test: win himself, accepting stay alive after committing an irremediable error. The dramatic action has dual motivation, human and divine. The human conflict requires resilience of families and friends of Heracles and the opposition of Lico is a key element to the action. In the subsequent clash between Heracles and the goddess Hera, victory lies with the deity, motivating the disaster, but confirms the heroics of Heracles, that resists the urge to annihilation after the murder of children. His friend, King Theseus, provides him the support needed to dissuade him from his purpose of annihilation and strengthens him for endurance. The valuation of philia is an important element in shaping the sense of this euripidean text.