5,907 research outputs found
Uniqueness of canonical tensor model with local time
Canonical formalism of the rank-three tensor model has recently been
proposed, in which "local" time is consistently incorporated by a set of first
class constraints. By brute-force analysis, this paper shows that there exist
only two forms of a Hamiltonian constraint which satisfies the following
assumptions: (i) A Hamiltonian constraint has one index. (ii) The kinematical
symmetry is given by an orthogonal group. (iii) A consistent first class
constraint algebra is formed by a Hamiltonian constraint and the generators of
the kinematical symmetry. (iv) A Hamiltonian constraint is invariant under time
reversal transformation. (v) A Hamiltonian constraint is an at most cubic
polynomial function of canonical variables. (vi) There are no disconnected
terms in a constraint algebra. The two forms are the same except for a slight
difference in index contractions. The Hamiltonian constraint which was obtained
in the previous paper and behaved oddly under time reversal symmetry can
actually be transformed to one of them by a canonical change of variables. The
two-fold uniqueness is shown up to the potential ambiguity of adding terms
which vanish in the limit of pure gravitational physics.Comment: 21 pages, 12 figures. The final result unchanged. Section 5 rewritten
for clearer discussions. The range of uniqueness commented in the final
section. Some other minor correction
Aquecimento global e pecuária: o que todo pecuarista deve saber sobre ele.
bitstream/item/77619/1/-Aquecimento-global-e-pecuaria-o-que-todo-pecuarista-deve-saber-sobre-ele-BeefPoint.pd
Valor nutricional da carne bovina e suas implicações para a saúde humana.
A carne bovina tem seu consumo restrito por recomendação de médicos e nutricionistas em função do seu teor de gordura saturada. Todavia, essa recomendação deveria ser revista em função de falhas na hipótese lipídica e a descoberta de características específicas de ácidos graxos presentes na carne. O consumo restrito de carne, em função da tentativa de reduzir o consumo de gordura saturada, pode estar fazendo com que quantidades subótimas de nutrientes, os quais a carne seja importante fonte (exemplos: ácidos graxos poliinsaturados de cadeia longa, vitamina B12, zinco, ferro e outros) estejam sendo consumidas. Além disso, os alimentos utilizados em sua substituição, ricos em carboidratos simples e gordura vegetal hidrogenada, podem ser responsáveis pelo aumento da ocorrência de várias doenças crônicas associadas com o consumo de excesso de gordura. Procurou-se mostrar, fundamentado em dados científicos recentes, que a carne bovina deve fazer parte de uma dieta diversificada e bem balanceada para o aumento da qualidade de vida da população.bitstream/CNPGC-2009-09/12406/1/DOC171.pd
Boi orgânico, boi verde e convencional podem ir mais longe, caminhando na mesma direção.
bitstream/CPAP/56444/1/ADM021.pdfFormato eletrônico
How good are MatLab, Octave and Scilab for Computational Modelling?
In this article we test the accuracy of three platforms used in computational
modelling: MatLab, Octave and Scilab, running on i386 architecture and three
operating systems (Windows, Ubuntu and Mac OS). We submitted them to numerical
tests using standard data sets and using the functions provided by each
platform. A Monte Carlo study was conducted in some of the datasets in order to
verify the stability of the results with respect to small departures from the
original input. We propose a set of operations which include the computation of
matrix determinants and eigenvalues, whose results are known. We also used data
provided by NIST (National Institute of Standards and Technology), a protocol
which includes the computation of basic univariate statistics (mean, standard
deviation and first-lag correlation), linear regression and extremes of
probability distributions. The assessment was made comparing the results
computed by the platforms with certified values, that is, known results,
computing the number of correct significant digits.Comment: Accepted for publication in the Computational and Applied Mathematics
journa
Quasi-degenerate neutrinos and tri-bi-maximal mixing
We consider how, for quasi-degenerate neutrinos with tri-bi-maximal mixing at
a high-energy scale, the mixing angles are affected by radiative running from
high to low-energy scales in a supersymmetric theory. The limits on the
high-energy scale that follow from consistency with the observed mixing are
determined. We construct a model in which a non-Abelian discrete family
symmetry leads both to a quasi-degenerate neutrino mass spectrum and to near
tri-bi-maximal mixing.Comment: 8 pages, 3 figure
Preparo e uso de soluções salinas saturadas para a caracterização fisiológica de sementes florestais.
bitstream/CNPF-2009-09/41217/1/circ-tec125.pd
Torsion-Adding and Asymptotic Winding Number for Periodic Window Sequences
In parameter space of nonlinear dynamical systems, windows of periodic states
are aligned following routes of period-adding configuring periodic window
sequences. In state space of driven nonlinear oscillators, we determine the
torsion associated with the periodic states and identify regions of uniform
torsion in the window sequences. Moreover, we find that the measured of torsion
differs by a constant between successive windows in periodic window sequences.
We call this phenomenon as torsion-adding. Finally, combining the torsion and
the period adding rules, we deduce a general rule to obtain the asymptotic
winding number in the accumulation limit of such periodic window sequences
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