On the dimensional dependence of duality groups for massive p-forms

We study the soldering formalism in the context of abelian p-form theories. We develop further the fusion process of massless antisymmetric tensors of different ranks into a massive p-form and establish its duality properties. To illustrate the formalism we consider two situations. First the soldering mass generation mechanism is compared with the Higgs and Julia-Toulouse mechanisms for mass generation due to condensation of electric and magnetic topological defects. We show that the soldering mechanism interpolates between them for even dimensional spacetimes, in this way confirming the Higgs/Julia-Toulouse duality proposed by Quevedo and Trugenberger \cite{QT} a few years ago. Next, soldering is applied to the study of duality group classification of the massive forms. We show a dichotomy controlled by the parity of the operator defining the symplectic structure of the theory and find their explicit actions.Comment: Reference [8] has been properly place

On duality of the noncommutative extension of the Maxwell-Chern-Simons model

We study issues of duality in 3D field theory models over a canonical noncommutative spacetime and obtain the noncommutative extension of the Self-Dual model induced by the Seiberg-Witten map. We apply the dual projection technique to uncover some properties of the noncommutative Maxwell-Chern-Simons theory up to first-order in the noncommutative parameter. A duality between this theory and a model similar to the ordinary self-dual model is estabilished. The correspondence of the basic fields is obtained and the equivalence of algebras and equations of motion are directly verified. We also comment on previous results in this subject.Comment: Revtex, 9 pages, accepted for publication PL

A nearly cylindrically symmetric source in the Brans-Dicke gravity as the generator of the rotational curves of the galaxies

Observation shows that the velocities of stars grow by approximately 2 to 3 orders of magnitude when the distances from the centers of the galaxies are in the range of $0.5$ kpc to $82.3$ kpc, before they begin to tend to a constant value. Up to know, the reason for this behavior is still a matter for debate. In this work, we propose a model which adequately describes this unusual behavior using a (nearly) cylindrical symmetrical solution in the framework of a scalar-tensor-like (the Brans-Dicke model) theory of gravity.Comment: 24 pages, 4 figures, accepted for publication in Eur. Phys. J.

Massive scalar field near a cosmic string

The $\zeta$ function of a massive scalar field near a cosmic string is computed and then employed to find the vacuum fluctuation of the field. The vacuum expectation value of the energy-momentum tensor is also computed using a point-splitting approach. The obtained results could be useful also for the case of self-interacting scalar fields and for the finite-temperature Rindler space theory.Comment: 15 pages, standard LaTeX, no figures. Reference [14] correcte

Collapse of an ecological network in Ancient Egypt

The dynamics of ecosystem collapse are fundamental to determining how and why biological communities change through time, as well as the potential effects of extinctions on ecosystems. Here we integrate depictions of mammals from Egyptian antiquity with direct lines of paleontological and archeological evidence to infer local extinctions and community dynamics over a 6000-year span. The unprecedented temporal resolution of this data set enables examination of how the tandem effects of human population growth and climate change can disrupt mammalian communities. We show that the extinctions of mammals in Egypt were nonrandom, and that destabilizing changes in community composition coincided with abrupt aridification events and the attendant collapses of some complex societies. We also show that the roles of species in a community can change over time, and that persistence is predicted by measures of species sensitivity, a function of local dynamic stability. Our study is the first high-resolution analysis of the ecological impacts of environmental change on predator-prey networks over millennial timescales, and sheds light on the historical events that have shaped modern animal communities

Desempenho produtivo de cultivares de milho nas microrregiões de Paragominas, Belterra e Uruará no Estado do Pará.

O rendimento das lavouras de milho no Estado vem aumentando gradativamente, devido ao uso de variedades e de híbridos que vêm sendo desenvolvidas pela pesquisa, aliadas às práticas culturais mais modernas. Torna-se fundamental desenvolver atividades voltadas para a avaliação de variedades e híbridos, visando à seleção de materiais adaptados e com atributos agronômicos desejáveis. O objetivo foi avaliar híbridos pré - comerciais e comerciais de milho, visando recomendar cultivares de alta produtividade e adaptadas às condições ambientais do Nordeste e Oeste paraense. Utilizou-se o esquema de latice 7 x 7, com duas repetições. Na análise, foi detectada diferença estatística, a 1 % de probabilidade pelo teste F, para tratamentos, indicando a existência de diferenças genéticas entre as cultivares. A diferença mínima significativa (DMS t), a 1 %de probabilidade, foi de 1880 kg/ha de grãos. A amplitude de variação ficou entre 8.643 kg/ha (144 sacos) e 3.844 kg/ha (64 sacos), com média de 5.998 kg/ha (100 sacos). Os resultados sugerem a indicação e recomendação para plantio nessas regiões as cultivares: 2B604 HX (8.643), BRS 1060 (8.634), 30A86 HX (8.577), BH 9546 (8.306), P30F35 (7.993), 2B707 (7.926) e BRS 1055 (7.460) por apresentarem bom desempenho produtivo e outras características de interesse

Carbon nanotube: a low-loss spin-current waveguide

We demonstrate with a quantum-mechanical approach that carbon nanotubes are excellent spin-current waveguides and are able to carry information stored in a precessing magnetic moment for long distances with very little dispersion and with tunable degrees of attenuation. Pulsed magnetic excitations are predicted to travel with the nanotube Fermi velocity and are able to induce similar excitations in remote locations. Such an efficient way of transporting magnetic information suggests that nanotubes are promising candidates for memory devices with fast magnetization switchings

Serum Lipids and Prostate Cancer

Background: Conflicting results are found in the literature relating serum lipids levels and prostate cancer. Some results imply a relationship between them; others contradict this association. The purpose of this study was to investigate a possible association between serum lipids levels and prostate cancer, at time of diagnosis. Methods: We measured serum levels of total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides in 237 patients submitted to a prostate biopsy, with PSA between 2 and 10 ng/ml. Patients without cancer at biopsy were used as controls, and the others were considered as cases. No information about lipid-lowering therapy, including statins, was available neither in cases nor in controls. Cases were divided into risk groups, according to the disease severity, based on staging. Lipids levels were compared between groups, using parametric and nonparametric tests. Logistic regression analysis and odds ratios were calculated. Results: LDL and total cholesterol levels were lower in patients with cancer, with the difference being statistically significant for LDL cholesterol (p = 0.010) and borderline for total cholesterol (p = 0.050). No significant differences were found between the several risk groups. Odds ratios for low LDL cholesterol (<130 mg/dl) and low total cholesterol (<200 mg/dl), with prostate cancer as the outcome, were 1.983 and 1.703, respectively. There were no significant differences between cases and controls for the other lipids. Conclusion: Lower LDL cholesterol (<130 mg/dl) and lower total cholesterol (<200 mg/dl) serum levels seem to associate with prostate cancer, at time of diagnosis.info:eu-repo/semantics/publishedVersio

Análise do custo de produção e comercialização da manga produzida e exportada na região do Submédio São Francisco.

A região do Submédio São Francisco é atualmente um dos principais pólo de produção e o maior de exportação de manga do país, com uma área plantada de cerca de 25 mil hectares, concentrados principalmente nos municípios de Petrolina, Pernambuco e Juazeiro, Bahia. Deste aproximadamente 70% dos cultivos estão em crescente ou plena produção e 30% ainda em implantação. Trata-se de cultivos de alta tecnologia e grandes consumidires de capital, situação que exige que o produtor além de uma alta produtividade física obtenha também uma adequada rentabilidade econômica. Este trabalho teve como objetivo analisar os custos de produção e a rentabilidade da manga produzida na região do Submédio São Francisco e comercializada no mercado internacional. Os dados foram levantados nas empresas típicas de produção, beneficiamento e exportação de manga da região em estudo e para a determinação da viabilidade econômica da exploração utilizou-se o método de orçamentos de custos e receitas. Com relação a produção foram levantados os custos diretos e indiretos da manutenção de um hectare de mangueira em produção plena e no tocante a comercialização foram obtidos desde os custos da recepção do produto no paking house, até a entrega do mesmo no mercado de destino. Os resultados indicaram que em uma caixa exportada de manga, que pesa 4,20 kg, são gastos US$0,55 com a produção, US$ 2,09 com o beneficiamento, US$1,51 com transporte e despesas de aduanas e US$ 0,48 com a comissão do importador. Como o preço médio anual da caixa de manga no mercado Norte Americano é US$6,0 o produtor obtém por unidade vendida uma margem líquida de US$ 1,37 e uma relação benefício custo de US$ 1,29