A discrete finite-dimensional phase space approach for the description of Fe8 magnetic clusters: Wigner and Husimi functions

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The Schrodinger and Pauli-Dirac Oscillators in Noncommutative Phase Space

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effective potential in curved space and cut-off regularizations

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Noncommutative fluid dynamics in the Snyder space-time

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Characterization of multiple reflections and phase space properties for a periodically corrugated waveguide

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Parameter space for a dissipative Fermi-Ulam model

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

Monte Carlo renormalization group with evolution in the space of parameters

Using data from a single simulation we obtain Monte Carlo renormalization-group information in a finite region of parameter space by adapting the Ferrenberg-Swendsen histogram method. Several quantities are calculated in the two-dimensional N 2 Ashkin-Teller and Ising models to show the feasibility of the method. We show renormalization-group Hamiltonian flows and critical-point location by matching of correlations by doing just two simulations at a single temperature in lattices of different sizes to partially eliminate finite-size effects.

The symmetry group of Z(q)(n) in the Lee space and the Z(qn)-linear codes

The Z(4)-linearity is a construction technique of good binary codes. Motivated by this property, we address the problem of extending the Z(4)-linearity to Z(q)n-linearity. In this direction, we consider the n-dimensional Lee space of order q, that is, (Z(q)(n), d(L)), as one of the most interesting spaces for coding applications. We establish the symmetry group of Z(q)(n) for any n and q by determining its isometries. We also show that there is no cyclic subgroup of order q(n) in Gamma(Z(q)(n)) acting transitively in Z(q)(n). Therefore, there exists no Z(q)n-linear code with respect to the cyclic subgroup.

Two-dimensional induced gravity in reduced phase-space

We discuss the Dirac method analysis of two-dimensional induced gravity, coupled to bosonic matter fields, in reduced phase-space. After defining the extended Hamiltonian it is possible to fix the gauge completely. The Dirac brackets can all be obtained in closed form; nevertheless, the results are not particularly simple.

SEASONAL SPACE USAGE BY THE INTRODUCED PHARAOHS ANT, MONOMORIUM-PHARAONIS (L) (HYM, FORMICIDAE), IN INSTITUTIONAL SETTINGS IN BRAZIL AND ITS RELATION TO OTHER STRUCTURAL ANT SPECIES

In an institutional setting in Brazil, the pharaoh's ant, Monomorium pharaonis was found to be the dominant and most abundant ant present throughout the year. The only other regularly collected ant was the exotic Tapinoma melanocephalum. However, M. pharaonis dominated bait station visitations, although locally concentrated, with other species restricted to regions in which M. pharaonis was not found.

Effects of the postannealing atmosphere on the dielectric properties of (Ba, Sr)TiO3 capacitors: Evidence of an interfacial space charge layer

The dielectric properties of (Ba, Sr)TiO3 films were found to be remarkably sensitive to the postannealing treatment atmosphere. This study demonstrates that postannealing in an oxygen atmosphere increases the dielectric relaxation phenomenon and that postannealing in a nitrogen atmosphere produces a slight dielectric relaxation. Such dependence of the dielectric relaxation was related both to oxygen vacancies and to the presence of negatively charged oxygen, trapped at the grain boundary and/or at the electrode/dielectric film interface. (C) 2000 American Institute of Physics. [S0003-6951(00)00817-2].

Optimal space manoeuvres in a non-Keplerian force field

In this work the problem of a spacecraft bi-impulsive transfer between two given non coplanar elliptical orbits, with minimum fuel consumption, is solved considering a non-Keplerian force field (the perturbing forces include Earth gravity harmonics and atmospheric drag). The problem is transformed in the Two Point Boundary Value Problem. It is developed and implemented a new algorithm, that uses the analytical expressions developed here. A dynamics that considered a Keplerian force field was used to produce an initial guess to solve the Two Point Boundary Value Problem. Several simulations were performed to observe the spacecraft orbital behaviour by different kind of perturbations and constraints, on a fuel consumption optimization point of view. (C) 2002 COSPAR. Published by Elsevier B.V. Ltd. All rights reserved.

The Liapunov exponent as a tool for exploring phase space

We have used the Liapunov exponent to explore the phase space of a dynamical system. Considering the planar, circular restricted three-body problem for a mass ratio mu = 10(-3) (close to the Jupiter/Sun case), we have integrated similar to 16,000 starting conditions for orbits started interior to that of the perturber and we have estimated the maximum Liapunov characteristic exponent for each starting condition. Despite the fact that the integrations, in general, are for only a few thousand orbital periods of the secondary, a comparative analysis of the Liapunov exponents for various values of the 'cut-off' gives a good overview of the structure of the phase space. It provides information about the diffusion rates of the various chaotic regions, the location of the regular regions associated with primary resonances and even details such as the location of secondary resonances that produce chaotic regions inside the regular regions of primary resonances.

On the hardy space H¹ on products of half-spaces

We show that the Hardy space H¹ anal (R2+ x R2+) can be identified with the class of functions f such that f and all its double and partial Hubert transforms Hk f belong to L¹ (R2). A basic tool used in the proof is the bisubharmonicity of |F|q, where F is a vector field that satisfies a generalized conjugate system of Cauchy-Riemann type.