The three-dimensional non-anticommutative superspace

We propose two alternative formulations for a three-dimensional non-anticommutative superspace in which some of the fermionic coordinates obey Clifford anticommutation relations. For this superspace, we construct the supersymmetry generators satisfying standard anticommutation relations and the corresponding supercovariant derivatives. We formulate a scalar superfield theory in such a superspace and calculate its propagator. We also suggest a prescription for the introduction of interactions in such theories.Comment: 9 pages, revtex4, v3: some clarifications and references added, version accepted for publication in Phys.Rev.

The Noncommutative Anandan's Quantum Phase

In this work we study the noncommutative nonrelativistic quantum dynamics of a neutral particle, that possesses permanent magnetic and electric dipole momenta, in the presence of an electric and magnetic fields. We use the Foldy-Wouthuysen transformation of the Dirac spinor with a non-minimal coupling to obtain the nonrelativistic limit. In this limit, we will study the noncommutative quantum dynamics and obtain the noncommutative Anandan's geometric phase. We analyze the situation where magnetic dipole moment of the particle is zero and we obtain the noncommutative version of the He-McKellar-Wilkens effect. We demonstrate that this phase in the noncommutative case is a geometric dispersive phase. We also investigate this geometric phase considering the noncommutativity in the phase space and the Anandan's phase is obtained.Comment: 15 pages, revtex4, version to appear in Physical Review

Indicativo agroclimático para o cultivo do piquiá no estado do Pará (1º aproximação).

O piquiazeiro (Caryocar villosum, Aubl.) é arvore nativa da bacia Amazônica, sendo mais encontrada em mata primária de terra firme do estuário Amazônico. Embora apresente grande potencial econômico pelo alto grau de aproveitamento de seus produtos, essa planta é ainda muito pouco explorada se concentrando mais no extrativismo, para a retirada da madeira de alto valor comercial. Entre os produtos mais conhecidos do piquiazeiro estão os frutos comestiveis ricos em vitaminas, proteinas e sais minerais e a madeira de qualidade superior, com utilidade para a construção civil e náutica. A planta se enquadra ainda na categoria de melífera e ornamental evidenciando assim ser o cultivo do piquiá uma excelente opção econômica para o Estado. Este trabalho apresenta informações sobre a viabilidade agroclimática para o cultivo do piquiazeiro no Pará. O objetivo é subsidiar o planejamento e práticas agrícolas com informações de exigências agroclimáticas para a obtenção do bom rendimento da planta. Os resultados obtidos mostram que, em geral, o piquiá pode se cultivado em todo o território paraense, com dez microrregiões apresentando condições agroclimáticas preferenciais, onze microrregiões condições regulares e 1 microrregião condição marginal

Traditional vegetables: preliminary studies on seeds of vinegar (Hibiscus sabdariffae L.).

Abstract 96

Attractive Forces Between Electrons in QED3_{3}

Vacuum polarization effects are non-perturbatively incorporated into the photon propagator to eliminate the severe infrared problems characteristic of QED$_3$. The theory is thus rephrased in terms of a massive vector boson whose mass is $e^2/(8\pi)$. Subsequently, it is shown that electron-electron bound states are possible in QED$_3$.Comment: revtex, 10 pages and four figures, IFUSP/P-98

Evidence for two-electron processes in the mutual neutralization of O- with O+ and N+ at Subthermal Collision Energies

We have measured total absolute cross sections for the Mutual Neutralization (MN) of O- with O+/N+. A fine resolution (of about 50 meV) in the kinetic energy spectra of the product neutral atoms allows unique identification of the atomic states participating in the mutual neutralization process. Cross sections and branching ratios have also been calculated down to 1 meV center-of-mass collision energy for these two systems with a multi-channel Landau-Zener model and an asymptotic method for the ionic-covalent coupling matrix elements. The importance of two-electron processes in one-electron transfer is demonstrated by the dominant contribution of a core-excited configuration of the nitrogen atom in N+ + O- collisions. This effect is partially accounted for by introducing configuration mixing in the evaluation of coupling matrix elements.Comment: 5 pages, 4 figure

Estrutura populacional de espécies de interesse florestal não-madeireiro no Sudeste do Pará, Brasil.

O trabalho descreve a estrutura populacional de cinco espécies com potencial para a exploração sustentável de produtos florestais não-madeireiros na região Sudeste do estado do Pará, Brasil. As espécies, naturalmente comuns na região foram: castanha-do-pará ( Bertholletia excelsa Bonpl. - Lecythidaceae), andiroba ( Carapa guianensis Aubl. - Meliaceae), copaíba ( Copaifera sp. - Fabaceae), uxi ( Endopleura uchi [Huber] Cuatrec. - Humiriaceae) e cupuaçu ( Theobroma grandiflorum [Willd. ex Spreng.] K. Schum. - Sterculiaceae). As cinco espécies foram estudadas em 17 parcelas de um hectare (20m x 500m) num assentamento agroextrativista no município de Nova Ipixuna. No inventário foram encontrados 1.512 indivíduos em 109 morfoespécies com DAP?25cm onde se calculou a densidade, área basal e o volume estimado. Castanha-do-pará, andiroba e cupuaçu mostraram altas densidades (2,53±1,37; 2,76±2,17 e 2,12±1,90 indivíduos/ha ± um desvio padrão, respectivamente) o que sugere seu manejo para a exploração sustentável de produtos florestais não-madeireiros. Uxi e copaíba apresentaram baixas densidades (0,41±1,06 e 0,29±0,59 indivíduos/ha, respectivamente), o que não permite sugerir uma forma de manejo economicamente viável. Quanto à distribuição diamétrica, apenas andiroba apresentou uma distribuição em forma de J-reverso

Textile subwaste as a thermal insulation building material

This research work is focused on analyzing the potential application of textile subwaste as an alternative building thermal insulation material for double external walls, and in a sustainable perspective. The studied textile subwaste results from the mattress industry and it was briefly characterized as a material. Taking into account that it is necessary to achieve the thermal insulation performance of the proposed technological building solution an alternative expedite experimental setup is also proposed here. It was concluded that using the textile subwaste, a double external wall’s thermal insulation performance may be increased in 33%

Noncommutative fields in three dimensions and mass generation

We apply the noncommutative fields method for gauge theory in three dimensions where the Chern-Simons term is generated in the three-dimensional electrodynamics. Under the same procedure, the Chern-Simons term is shown to be cancelled in the Maxwell-Chern-Simons theory for the appropriate value of the noncommutativity parameter. Hence the mutual interchange between Maxwell-Chern-Simons theory and pure Maxwell theory turns out to be generated within this method.Comment: Comments 5 pages, epl, version accepted for publication in Europhysics Letter