The Fokker-Planck equation for a bistable potential

The Fokker-Planck equation is studied through its relation to a Schrodinger-type equation. The advantage of this combination is that we can construct the probability distribution of the Fokker-Planck equation by using well-known solutions of the Schrodinger equation. By making use of such a combination, we present the solution of the Fokker-Planck equation for a bistable potential related to a double oscillator. Thus, we can observe the temporal evolution of the system describing its dynamic properties such as the time tau to overcome the barrier. By calculating the rates k = 1/tau as a function of the inverse scaled temperature 1/D, where D is the diffusion coefficient, we compare the aspect of the curve k x 1/D, with the ones obtained from other studies related to four different kinds of activated process. We notice that there are similarities in some ranges of the scaled temperatures, where the different processes follow the Arrhenius behavior. We propose that the type of bistable potential used in this study may be used, qualitatively, as a simple model, whose rates share common features with the rates of some single rate-limited thermally activated processes. (C) 2014 Elsevier B.V. All rights reserved.

Time-dependent properties in two-dimensional and Hamiltonian mappings

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Scaling properties and universality in a ratchet system

Critical exponents that describe a transition from unlimited to limited diffusion for a ratchet system are obtained analytically and numerically. The system is described by a two dimensional nonlinear mapping with three relevant control parameters. Two of them control the non-linearity while the third one controls the intensity of the dissipation. Chaotic attractors appear in the phase space due to the dissipation and considering large non-linearity are characterised by the use of Lyapunov exponents. The critical exponents are used to overlap different curves of average momentum (dynamical variable) onto a single plot confirming a scale invariance. The formalism used is general and the procedure can be extended to different systems.

Formalismo canônico da mecânica clássica: alicerce da mecânica quântica

We present a succinct review of the canonical formalism of classical mechanics, followed by a brief review of the main representations of quantum mechanics. We emphasize the formal similarities between the corresponding equations. We notice that these similarities contributed to the formulation of quantum mechanics. Of course, the driving force behind the search of any new physics is based on experimental evidence

Orações subjetivas: variância e invariância de padrões na fala e na escrita

This work investigates the variance and invariance of subject clauses patterns in spoken and written contemporary Brazilian Portuguese. I analyze four parameters (category and semantic class of matrix predicate, form of embedded clause and mood-tense correlation between matrix and embedded clauses) and show that there is less variance in speech patterns.

Transformações de Bäcklund para hierarquias integráveis abelianas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Adaptação transcultural Brasil-Portugal da escala Brief Cope para estudantes do ensino superior

The aim of this study was to adapt the BriefCOPE Inventory for Portuguese-speaking university students. We evaluate the Portuguese BriefCOPE psychometrics qualities and estimated the BriefCOPE factorial invariance in Brazil and Portugal. The data collected from a sample of 1573 students of both nationalities did confirm the 14-factor structure of the BriefCOPE and showed both factorial, convergent and discriminant related validities. However, the factor model did not show invariance across countries indicating that the use of the Portuguese version of the BriefCOPE cannot be bailed for comparisons of scores of inter-countries' student coping.

Escala de estresse percebido aplicada a estudantes universitárias: estudo de validação

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

Validation of the weight concerns scale applied to brazilian university students

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

Weight concerns scale applied to college students: comparison between pencil-and-paper and online formats

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

Validation of the Geriatric Oral Health Assessment Index in complete denture wearers

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

Validation of a measuring instrument for the perception of oral health in women

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

O invariante E(G, W, M): algumas propriedades e aplicações na teoria de decomposição de grupos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Sistemas de controle em domínios estratificados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Equação de Schrödinger não linear com coeficientes modulados

Pós-graduação em Física - FEG