16,551 research outputs found

    Effective interactions from q-deformed inspired transformations

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    From the mass term for the transformed quark fields, we obtain effective contact interactions of the NJL type. The parameters of the model that maps a system of non-interacting transformed fields into quarks interacting via NJL contact terms are discussed

    On the q-deformation of the NJL model

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    Using a q-deformed fermionic algebra we perform explicitly a deformation of the Nambu-Jona-Lasinio (NJL) Hamiltonian. In the Bogoliubov-Valatin approach we obtain the deformed version of the functional for the total energy, which is minimized to obtain the corresponding gap equation. The breaking of chiral symmetry and its restoration in the limit q0q \to 0 are then discussed.Comment: 5 eps figure

    O tucumã (Astrocaryum vulgare Mart.) principais características e potencialidade agroindustrial.

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    Physical approximations for the nonlinear evolution of perturbations in dark energy scenarios

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    The abundance and distribution of collapsed objects such as galaxy clusters will become an important tool to investigate the nature of dark energy and dark matter. Number counts of very massive objects are sensitive not only to the equation of state of dark energy, which parametrizes the smooth component of its pressure, but also to the sound speed of dark energy as well, which determines the amount of pressure in inhomogeneous and collapsed structures. Since the evolution of these structures must be followed well into the nonlinear regime, and a fully relativistic framework for this regime does not exist yet, we compare two approximate schemes: the widely used spherical collapse model, and the pseudo-Newtonian approach. We show that both approximation schemes convey identical equations for the density contrast, when the pressure perturbation of dark energy is parametrized in terms of an effective sound speed. We also make a comparison of these approximate approaches to general relativity in the linearized regime, which lends some support to the approximations.Comment: 15 pages, 2 figure

    Is Thyroid Stunning Clinically Relevant? A Retrospective Analysis Of 208 Patients.

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    Current guidelines have advised against the performance of (131)I-iodide diagnostic whole body scintigraphy (dxWBS) to minimize the occurrence of stunning, and to guarantee the efficiency of radioiodine therapy (RIT). The aim of the study was to evaluate the impact of stunning on the efficacy of RIT and disease outcome. This retrospective analysis included 208 patients with differentiated thyroid cancer managed according to a same protocol and followed up for 12-159 months (mean 30 ± 69 months). Patients received RIT in doses ranging from 3,700 to 11,100 MBq (100 mCi to 300 mCi). Post-RIT-whole body scintigraphy images were performed 10 days after RIT in all patients. In addition, images were also performed 24-48 hours after therapy in 22 patients. Outcome was classified as no evidence of disease (NED), stable disease (SD) and progressive disease (PD). Thyroid stunning occurred in 40 patients (19.2%), including 26 patients with NED and 14 patients with SD. A multivariate analysis showed no association between disease outcome and the occurrence of stunning (p = 0.3476). The efficacy of RIT and disease outcome do not seem to be related to thyroid stunning.58292-30

    La gestion démocratique des écoles: de l´autogouvernement à l’émergence d’une post-démocratie gestionnaire?

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    O autor assinala três elementos básicos que têm sido historicamente associados à gestão democrática das escolas: eleição, colegialidade, participação na decisão. A combinação ou rejeição de algumas dessas diferentes dimensões, em contextos sociais específicos, pode resultar em várias concepções de gestão democrática das escolas, desde o autogoverno até à possível ascensão de uma pós-democracia gestionária.The author points out three basic elements that have been historically associated with the democratic management of schools: election, collegiality, participation in decision-making. The combination or the rejection of some of those different dimensions in specific social contexts may result in various conceptions of democratic management of schools, from selfgovernment to the possible rise of a managerial post-democracyL’auteur souligne trois éléments de base qui ont été historiquement associés à la gestion démocratique des écoles: l’élection, la collégialité, la participation à la décision. La combinaison ou le rejet de certaines de ces différentes dimensions, dans des contextes sociaux spécifiques, peuvent entraîner des diverses conceptions de la gestion démocratique des écoles, de l’autogouvernement à l’émergence d’une post-démocratie gestionnaire(undefined
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