5,685 research outputs found

    B+→K−π+π+B^+\to K^-\pi^+\pi^+: three-body final state interactions and KπK\pi isospin states

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    Final state interactions are considered to formulate the BB meson decay amplitude for the KππK\pi\pi channel. The Faddeev decomposition of the Bethe-Salpeter equation is used in order to build a relativistic three-body model within the light-front framework. The S-wave scattering amplitude for the KπK\pi system is considered in the 1/21/2 and 3/23/2 isospin channels with the set of inhomogeneous integral equations solved perturbatively. In comparison with previous results for the DD meson decay in the same channel, one has to consider the different partonic processes, which build the source amplitudes, and the larger absorption to other decay channels appears, that are important features to be addressed. As in the DD decay case, the convergence of the rescattering perturbative series is also achieved with two-loop contributions.Comment: 10 pages, 4 figure

    Point-Coupling Models from Mesonic Hypermassive Limit and Mean-Field Approaches

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    In this work we show how nonlinear point-coupling models, described by a Lagrangian density that presents only terms up to fourth order in the fermion condensate (ψˉψ)(\bar{\psi}\psi), are derived from a modified meson-exchange nonlinear Walecka model. The derivation can be done through two distinct methods, namely, the hypermassive meson limit within a functional integral approach, and the mean-field approximation in which equations of state at zero temperature of the nonlinear point-coupling models are directly obtained.Comment: 18 pages. Accepted for publication in Braz. J. Phy

    Estudio de metodologías de impregnación de Me2Si(Ind)2ZrCl2 sobre nanopartículas de MCM-41 para la síntesis de polipropileno

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    Nanopartículas de MCM-41 fueron utilizadas como soporte para el complejo metalocénico (Me2Si(Ind)2ZrCl2) y su cocatalizador metilaluminoxano (MAO), en la síntesis de polipropileno, Primeramente se estudiaron dos metodologías de impregnación, observando los efectos en la actividad catalítica y masa molecular. Con estos resultados posteriormente una tercera metodología de impregnación, más optimizada, fue utilizada consiguiendo significativas mejoras en la actividad catalítica. Los polímeros obtenidos fueron caracterizados por GPC y TGA. La utilización de estas nanopartículas como soporte dio lugar a la formación de nanocompósitos de polipropileno de manera in situ. La última metodología de impregnación empleada resultó ser adecuada para este propósito, ya que permite modificar la cantidad de soporte que se desea incorporar y variar la concentración de catalizador que será impregnada

    Preventing Atomicity Violations with Contracts

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    Software developers are expected to protect concurrent accesses to shared regions of memory with some mutual exclusion primitive that ensures atomicity properties to a sequence of program statements. This approach prevents data races but may fail to provide all necessary correctness properties.The composition of correlated atomic operations without further synchronization may cause atomicity violations. Atomic violations may be avoided by grouping the correlated atomic regions in a single larger atomic scope. Concurrent programs are particularly prone to atomicity violations when they use services provided by third party packages or modules, since the programmer may fail to identify which services are correlated. In this paper we propose to use contracts for concurrency, where the developer of a module writes a set of contract terms that specify which methods are correlated and must be executed in the same atomic scope. These contracts are then used to verify the correctness of the main program with respect to the usage of the module(s). If a contract is well defined and complete, and the main program respects it, then the program is safe from atomicity violations with respect to that module. We also propose a static analysis based methodology to verify contracts for concurrency that we applied to some real-world software packages. The bug we found in Tomcat 6.0 was immediately acknowledged and corrected by its development team

    Diagnóstico participativo em comunidades ribeirinhas na Amazônia: peixes e sua ecologia.

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    Este trabalho teve o objetivo de levantar o conhecimento do ribeirinho sobre a ecologia dos peixes em relação ao hábito alimentar, e quais as principais plantas utilizadas como alimento para estas populações locais por meio de oficinas participativas

    Endometriosis: A Rare Cause of Large Bowel Obstruction.

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    Large bowel obstruction can result in significant morbidity and mortality, especially in cases of acute complete obstruction. There are many possible causes, the most common in adults being colorectal cancer. Endometriosis is a benign disease, and the most affected extragenital location is the bowel, especially the rectosigmoid junction. However, transmural involvement and acute occlusion are very rare events. We report an exceptional case of acute large bowel obstruction as the initial presentation of endometriosis. The differential diagnosis of colorectal carcinoma may be challenging, and this case emphasizes the need to consider intestinal endometriosis in females at a fertile age presenting with gastrointestinal symptoms and an intestinal mass causing complete large bowel obstruction.info:eu-repo/semantics/publishedVersio

    Inspecção e reabilitação do Seminário Conciliar de Braga

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    Apresenta-se o diagnóstico, análise e reforço de um edifício dos anos 30, realizado essencialmente em betão armado, mas com paredes de contorno em cantaria de granito. Devido a uma alteração de uso, de seminário para arquivo, realizaram-se diferentes análises estruturais (lineares e não-lineares) para definir as condições de segurança do edifício. Dada a necessidade de reforço, discutem-se diferentes alternativas e detalha-se o projecto de execução

    Imaging Techniques in Breast Cancer

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    Existem vários métodos de Imagem que permitem avaliar a mama. Estes métodos têm conhecido uma evolução importante, quer por melhoria de técnicas como a mamografia, ecografia e Ressonância Magnética, quer pelo aparecimento de novas técnicas, como a tomossíntese. Os autores abordam as diferentes técnicas de Imagem da mama, as suas indicações e características, bem como alguns aspectos tecnológicos que correspondem a melhorias recentes
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