Gravitation: global formulation and quantum effects

A non-integrable phase-factor global approach to gravitation is developed by using the similarity of teleparallel gravity to electromagnetism. The phase shifts of both the COW and the gravitational Aharonov-Bohm effects are obtained. It is then shown, by considering a simple slit experiment, that in the classical limit the global approach yields the same result as the gravitational Lorentz force equation of teleparallel gravity. It represents, therefore, the quantum mechanical version of the classical description provided by the gravitational Lorentz force equation. As teleparallel gravity can be formulated independently of the equivalence principle, it will consequently require no generalization of this principle at the quantum level.

Semiclassical particle spectrum of double sine-Gordon model

We present new theoretical results on the spectrum of the quantum field theory of the double sine-Gordon model. This non-integrable model displays different varieties of kink excitations and bound states thereof. Their mass can be obtained by using a semiclassical expression of the matrix elements of the local fields. In certain regions of the coupling-constants space the semiclassical method provides a picture which is complementary to the one of the form factor perturbation theory, since the two techniques give information about the mass of different types of excitations. In other regions the two methods are comparable, since they describe the same kind of particles. Furthermore, the semiclassical picture is particularly suited to describe the phenomenon of false vacuum decay, and it also accounts in a natural way the presence of resonance states and the occurrence of a phase transition. (C) 2004 Elsevier B.V. All rights reserved.

Nonlocal charges for bonus yangian symmetries of Super-Yang-Mills

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Type-II Backlund transformations via gauge transformations

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

Nonvanishing boundary condition for the mKdV hierarchy and the Gardner equation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Grassmannian and bosonic Thirring models with jump defects

In this paper we discuss the Lax formulation of the Grassmannian and Bosonic Thirring models in the presence of jump defects. For the Grassmannian case, the defect is described by Backlund transformation which is responsible for preserving the integrability of the model. We then propose an extension of the Backlund transformation for the Bosonic Thirring model which is verified by some Backlund transitions like vacuum-one soliton, one soliton-one soliton, one soliton-two solitons and two solitons-two solitons. The Lax formulation within the space split by the defect leads to the integrability of Bosonic Thirring model with jump defects.

Asymmetric exclusion model with impurities

An integrable asymmetric exclusion process with impurities is formulated. The model displays the full spectrum of the stochastic asymmetric XXZ chain plus new levels. We derive the Bethe equations and calculate the spectral gap for the totally asymmetric diffusion at half filling. While the standard asymmetric exclusion process without impurities belongs to the KPZ universality class with an exponent 3/2, our model has a scaling exponent 5/3.

Negative Even Grade mKdV Hierarchy and its Soliton Solutions

In this paper we discuss the algebraic construction of the mKdV hierarchy in terms of an affine Lie algebra (s) over capl(2). An interesting novelty araises from the negative even grade sector of the affine algebra leading to nonlinear integro-differential equations admiting non-trivial vacuum configuration. These solitons solutions are constructed systematically from generalization of the dressing method based on non zero vacua. The sub-hierarchies admiting such class of solutions are classified.

Tunneling among rotation tori

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

Magnetic Field Line Escape: Comparison with Mean Free Path

In the present work, we determine the fraction of magnetic field lines that reach the tokamak wall leaving the plasma surrounded by a chaotic layer created by resonant perturbations at the plasma edge. The chaotic layer arises in a scenario where an integrable magnetic field with reversed magnetic shear is perturbed by an ergodic magnetic limiter. For each considered line, we calculate its connection length, i.e. the number of toroidal turns that the field lines complete before reaching the wall. We represent the results in the poloidal section in which the initial coordinates are chosen. We also estimate the radial profile of the fraction of field lines, for different temperatures, whose connection lengths are smaller than the electron collisional mean free path.

Stickiness in a bouncer model: A slowing mechanism for Fermi acceleration

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Quantum entanglement and fixed point Hopf bifurcation

We present the qualitative differences in the phase transitions of the mono-mode Dicke model in its integrable and chaotic versions. These qualitative differences are shown to be connected to the degree of entanglement of the ground state correlations as measured by the linear entropy. We show that a first order phase transition occurs in the integrable case whereas a second order in the chaotic one. This difference is also reflected in the classical limit: for the integrable case the stable fixed point in phase space undergoes a Hopf type whereas the second one a pitchfork type bifurcation. The calculation of the atomic Wigner functions of the ground state follows the same trends. Moreover, strong correlations are evidenced by its negative parts. (c) 2006 Elsevier B.V. All rights reserved.

Modalidades e hierarquias do crédito na cafeicultura paulista (1889-1930)

A partir do edifício teórico braudeliano investiga-se as modalidades de crédito praticadas na cafeicultura paulista, bem como as hierarquias que caracterizaram o seu funcionamento e organização. Lista-se neste artigo uma série de operações de crédito captadas por fontes documentais de diferentes naturezas, buscando subsidiar a discussão sobre a diversidade das formas de obtenção de crédito no espaço em questão. O ponto de nosso argumento é que o interior do estado, especializado na produção de café, joga papel fundamentalmente subordinado na hierarquia e na cadeia do crédito, dominada pelo grande capital cafeeiro, sendo que os mecanismos de concentração da riqueza e das oportunidades se situam mais destacadamente na capital paulista, que, por sua vez, também ocupa posição subordinada em relação aos principais centros capitalistas.

A clínica psicológica e o público LGBT

Tendo como base os estudos recentes sobre as sexualidades e os gêneros e, em especial, os relativos à diversidade sexual, este artigo promove uma discussão ética sobre as vicissitudes da clínica psicológica com a população LGBT (lésbicas, gays, bissexuais, travestis e transexuais). Para tanto, problematizamos a construção sócio-histórica-cultural da homossexualidade e da heterossexualidade, as hierarquias das sexualidades e algumas ações terapêuticas na clínica direcionada ao público não-heterossexual, tendo em vista a Resolução do Conselho Federal de Psicologia nº 1/99 que estabelece normas de atuação para os psicólogos em relação à questão da orientação sexual. Desse modo, matizamos o discurso da clínica usualmente orientada para o trabalho com pessoas heterossexuais, pensando de modo crítico o trabalho desenvolvido com sujeitos que transitam entre a vulnerabilidade e a invisibilidade devido a sua dissidência dos preceitos heteronormativos.

Evaluation of polymethylmethacrylate as ocular implant in rabbits subjected to evisceration

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)