Towards a knowledge-based system to assist the Brazilian data-collecting system operation

A study is reported which was carried out to show how a knowledge-based approach would lead to a flexible tool to assist the operation task in a satellite-based environmental data collection system. Some characteristics of a hypothesized system comprised of a satellite and a network of Interrogable Data Collecting Platforms (IDCPs) are pointed out. The Knowledge-Based Planning Assistant System (KBPAS) and some aspects about how knowledge is organized in the IDCP's domain are briefly described

Dimensionamento de piquetes para bovinos leiteiros, em sistemas de pastejo rotacionado.

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Produção de forragem e composição botânica de três espécies de pastagens tropicais sobressemeadas com aveia ou azevém.

O uso da sobressemeadura com espécies temperadas sobre pastagens tropicais apresenta vantagens técnicas e econômicas. Entretanto, a combinação entre as espécies necessita de mais estudos. Este trabalho teve por objetivo estudar nove combinações de espécies sobre a produção de forragem e composição botânica da pastagem. A Brachiaria brizantha cv. Marandu foi a espécie mais adaptada a sobressemeadura, permitindo que 50% do total de forragem colhida fosse representado pelas espécies temperadas (aveia ou azevém). O capim Coastcross produziu muita forragem na época seca, fato que permitiu 20% apenas de porcentagem de forragem da espécie temperada

Seleção preliminar de cultivares de alfafa sob pastejo em condições tropicais, no município de São Carlos, SP.

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Chaos and a Resonance Mechanism for Structure Formation in Inflationary Models

We exhibit a resonance mechanism of amplification of density perturbations in inflationary mo-dels, using a minimal set of ingredients (an effective cosmological constant, a scalar field minimally coupled to the gravitational field and matter), common to most models in the literature of inflation. This mechanism is based on the structure of homoclinic cylinders, emanating from an unstable periodic orbit in the neighborhood of a saddle-center critical point, present in the phase space of the model. The cylindrical structure induces oscillatory motions of the scales of the universe whenever the orbit visits the neighborhood of the saddle-center, before the universe enters a period of exponential expansion. The oscillations of the scale functions produce, by a resonance mechanism, the amplification of a selected wave number spectrum of density perturbations, and can explain the hierarchy of scales observed in the actual universe. The transversal crossings of the homoclinic cylinders induce chaos in the dynamics of the model, a fact intimately connected to the resonance mechanism occuring immediately before the exit to inflation.Comment: 4 pages. This essay received an Honorable Mention from the Gravity Research Foundation, 1998-Ed. To appear in Mod. Phys. Lett.

Transmission coefficient and two-fold degenerate discrete spectrum of spin-1 bosons in a double-step potential

The scattering of spin-1 bosons in a nonminimal vector double-step potential is described in terms of eigenstates of the helicity operator and it is shown that the transmission coefficient is insensitive to the choice of the polarization of the incident beam. Poles of the transmission amplitude reveal the existence of a two-fold degenerate spectrum. The results are interpreted in terms of solutions of two coupled effective Schr\"{o}dinger equations for a finite square well with additional $\delta$-functions situated at the borders.Comment: arXiv admin note: substantial text overlap with arXiv:1203.119