Angular Momentum of the BTZ Black Hole in the Teleparallel Geometry

We carry out the Hamiltonian formulation of the three- dimensional gravitational teleparallelism without imposing the time gauge condition, by rigorously performing the Legendre transform. Definition of the gravitational angular momentum arises by suitably interpreting the integral form of the constraint equation Gama^ik=0 as an angular momentum equation. The gravitational angular momentum is evaluated for the gravitational field of a rotating BTZ black hole.Comment: 17 pages, no figures, v2: some misprints corrected, Ref.s added, Eq.s revised, submitted to General Relativity and Gravitatio

Gravitational Collapse of Self-Similar and Shear-free Fluid with Heat Flow

A class of solutions to Einstein field equations is studied, which represents gravitational collapse of thick spherical shells made of self-similar and shear-free fluid with heat flow. It is shown that such shells satisfy all the energy conditions, and the corresponding collapse always forms naked singularities.Comment: 34 pages, 9 figures, late

Perturbed Self-Similar Massless Scalar Field in the Spacetimes with Circular Symmetry in 2+1 Gravity

We present in this work the study of the linear perturbations of the 2+1-dimensional circularly symmetric solution, obtained in a previous work, with kinematic self-similarity of the second kind. We have obtained an exact solution for the perturbation equations and the possible perturbation modes. We have shown that the background solution is a stable solution.Comment: no figure

OGSA/Globus Evaluation for Data Intensive Applications

We present an architecture of Globus Toolkit 3 based testbed intended for evaluation of applicability of the Open Grid Service Architecture (OGSA) for Data Intensive Applications.Comment: To be published in the proceedings of the XIX International Symposium on Nuclear Electronics and Computing (NEC'2003), Bulgaria, Varna, 15-20 September, 200

Fermionic dark matter-photon quantum interaction: A mechanism for darkness

ELKO fermionic fields are prime candidates to describe dark matter, due to their intrinsic neutral nature, as they are constructed as eigenstates of the charge conjugation operator with dual helicity. To formulate the meaning of the darkness, the ELKO-photon coupling is scrutinized with a Pauli-like interaction, and the path integral is then formulated from the phase space constraint structure. Ward-Takahashi-like identities and Schwinger-Dyson equations, together with renormalizability, are employed to investigate a phenomenological mechanism to avoid external light signals. Accordingly, the non-polarized pair annihilation and Compton-like processes are shown to vanish at the limit of small scattering angles even if considering 1-loop radiative corrections, reinforcing the ELKO dark matter interpretation. However, ELKO interactions with nucleons are still possible. Motivated by recent nucleon-recoil experiments to detect dark matter, we furnish a consistent theoretical setup to describe ELKO-photon interaction compatible with the prevalence of darkness.Comment: 42 pages, 6 figure

Avaliação da dinâmica da paisagem da ilha do Mosqueiro, município de Belém, Pará.

The municipality of Belém, Pará, Brazil, has an area of about 505 km2 , of which 66% corresponds to the insular region, with the biggest, Mosqueiro Island, contributing 41% of total municipal area. This island presents a very heterogenous landscape in terms of the kind of occupation and economic activities developed due to different edaphic and socio-economic factors. In this study, to characterize the vegetation and land use, TM/Landsat images for 1990 and 1995 were used, with the support of field surveys. A change in 53% of the natural vegetation cover of the study area was observed, were being an average forest area loss of 1 km2 /yr over the period. The analyses permit the proposal to create conservations units and generate information on the dynamics of land use. Thus, the set of the results obtained are potentially important for planning the develoment of various activities on the island and the remote sensing and geoprocessing products and techniques, the tool responsible for a fast and efficient monitoring and control

Flutuação populacional de Rhynchophorus palmarum (L.) (Coleoptera: Curculionidae) em palmeiras oleíferas no Amazonas.

As coleobrocas são umas das principais pragas das palmeiras devido aos seus danos diretos e indiretos resultarem na morte de diversas plantas. O levantamento populacional destes insetos é de extrema importância, visto a necessidade de se manejar adequadamente o controle realizado na área. Este estudo teve como objetivo monitorar a flutuação populacional de Rhynchophorus palmarum em plantios comerciais de Elaeis guineensis Jacq. e E. oleífera (HBK) Cortes, no estado do Amazonas

Análise de Repetibilidade em Caracteres de Arquitetura da Planta e Produção em Pinhão-manso.

O objetivo deste trabalho foi estimar os coeficientes de repetibilidade para produção de grãos, números de ramos, altura e volume de copa do pinhão-manso, nos 10 e 20 anos pós-plantio