The complex Sine-Gordon equation as a symmetry flow of the AKNS Hierarchy

It is shown how the complex sine-Gordon equation arises as a symmetry flow of the AKNS hierarchy. The AKNS hierarchy is extended by the ``negative'' symmetry flows forming the Borel loop algebra. The complex sine-Gordon and the vector Nonlinear Schrodinger equations appear as lowest negative and second positive flows within the extended hierarchy. This is fully analogous to the well-known connection between the sine-Gordon and mKdV equations within the extended mKdV hierarchy. A general formalism for a Toda-like symmetry occupying the ``negative'' sector of sl(N) constrained KP hierarchy and giving rise to the negative Borel sl(N) loop algebra is indicated.Comment: 8 pages, LaTeX, typos corrected, references update

Crescimento de Eucalyptus benthamii submetido à aplicação de lama de cal e cinza de madeira.

bitstream/item/145220/1/CT-373-Maeda.pd

Four Fermion Field Theories and the Chern-Simons Field: A Renormalization Group Study

In (2+1) dimensions, we consider the model of a $N$ flavor, two-component fermionic field interacting through a Chern-Simons field besides a four fermion self-interaction which consists of a linear combination of the Gross-Neveu and Thirring like terms. The four fermion interaction is not perturbatively renormalizable and the model is taken as an effective field theory in the region of low momenta. Using Zimmerman procedure for reducing coupling constants, it is verified that, for small values of the Chern-Simons parameter, the origin is an infrared stable fixed point but changes to ultraviolet stable as $\alpha$ becomes bigger than a critical $\alpha_c$. Composite operators are also analyzed and it is shown that a specific four fermion interaction has an improved ultraviolet behavior as $N$ increases.Comment: 9 pages, revte

Caracterização da produção, fenologia e sistema de manejo do coqueiro anão verde nos tabuleiros costeiros.

bitstream/item/26146/1/f-15.pd

Características quimico-nutricionais da polpa de Caryocar coriaceum WITTM da região Meio-Norte do Brasil.

A espécie Caryocar coriaceum (pequi) é típica da região Meio-Norte do Brasil e de outras regiões do Nordeste, onde faz parte da sua culinária e do dia-a-dia nordestino. Objetivou-se neste trabalho avaliar características químicas e nutricionais da polpa de pequi, de origem dos Estados do Piauí e Maranhão. As seguintes características foram avaliadas: acidez total titulável (ATT), pH, e percentagens de gordura (GORD), proteína bruta (PB), fibra bruta (FB) e carboidratos (CT). Os resultados indicam que a variabilidade é bem maior entre indivíduos nas diversas populações que entre populações. Em geral, maiores teores de GORD e FB foram obtidos em indivíduos de populações do Maranhão, ao passo que em PB os maiores foram observados em indivíduos provenientes de populações do Piauí

Exponentially hard problems are sometimes polynomial, a large deviation analysis of search algorithms for the random Satisfiability problem, and its application to stop-and-restart resolutions

A large deviation analysis of the solving complexity of random 3-Satisfiability instances slightly below threshold is presented. While finding a solution for such instances demands an exponential effort with high probability, we show that an exponentially small fraction of resolutions require a computation scaling linearly in the size of the instance only. This exponentially small probability of easy resolutions is analytically calculated, and the corresponding exponent shown to be smaller (in absolute value) than the growth exponent of the typical resolution time. Our study therefore gives some theoretical basis to heuristic stop-and-restart solving procedures, and suggests a natural cut-off (the size of the instance) for the restart.Comment: Revtex file, 4 figure

Reação de genótipos de batata à requeima (Phytophthora infestans).

bitstream/item/30474/1/boletim-83.pd