2,493 research outputs found

    Renormalized Equilibria of a Schloegl Model Lattice Gas

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    A lattice gas model for Schloegl's second chemical reaction is described and analyzed. Because the lattice gas does not obey a semi-detailed-balance condition, the equilibria are non-Gibbsian. In spite of this, a self-consistent set of equations for the exact homogeneous equilibria are described, using a generalized cluster-expansion scheme. These equations are solved in the two-particle BBGKY approximation, and the results are compared to numerical experiment. It is found that this approximation describes the equilibria far more accurately than the Boltzmann approximation. It is also found, however, that spurious solutions to the equilibrium equations appear which can only be removed by including effects due to three-particle correlations.Comment: 21 pages, REVTe

    Doses de calcário e outros fatores afetando a produção de melancia na terra firme do Amazonas.

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    Objetivou-se testar doses de calcário e, adicionalmente, outros fatores, para a melancia cultivada nas condições de terra firme do Estado do Amazonas. O ensaio foi instalado na Embrapa Amazônia Ocidental, Iranduba-AM, de julho a outubro de 2009

    Efeito da pré-embebição na germinação de sementes de coentro (Coriandro sativum L.).

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    Este trabalho foi realizado com o objetivo de avaliar o comportamento fisiológico das sementes de coentro submetidas a diferentes períodos de imersão em água, visando acelerar e uniformizar o processo germinativo

    Chemical abundances for 11 bulge stars from high-resolution, near-IR spectra

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    It is debated whether the Milky Way bulge has the characteristics of a classical bulge sooner than those of a pseudobulge. Detailed abundance studies of bulge stars is a key to investigate the origin, history, and classification of the bulge. The aim is to add to the discussion on the origin of the bulge and to study detailed abundances determined from near-IR spectra for bulge giants already investigated with optical spectra, the latter also providing the stellar parameters which are very significant for the results of the present study. Especially, the important CNO elements are better determined in the near-IR. High-resolution, near-infrared spectra in the H band are recorded using the CRIRES spectrometer on the Very Large Telescope. The CNO abundances can all be determined from the numerous molecular lines in the wavelength range observed. Abundances of the alpha elements are also determined from the near-IR spectra. [O/Fe], [Si/Fe] and [S/Fe] are enhanced up to metallicities of at least [Fe/H]=-0.3, after which they decline. This suggests that the Milky Way bulge experienced a rapid and early star-formation history like that of a classical bulge. However, a similarity between the bulge trend and the trend of the local thick disk seems present. Such a similarity could suggest that the bulge has a pseudobulge origin. Our [C/Fe] trend does not show any increase with [Fe/H] which could have been expected if W-R stars have contributed substantially to the C abundances. No "cosmic scatter" can be traced around our observed abundance trends; the scatter found is expected, given the observational uncertainties.Comment: Accepted for publication in A&

    Nontrivial temporal scaling in a Galilean stick-slip dynamics

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    We examine the stick-slip fluctuating response of a rough massive non-rotating cylinder moving on a rough inclined groove which is submitted to weak external perturbations and which is maintained well below the angle of repose. The experiments presented here, which are reminiscent of the Galileo's works with rolling objects on inclines, have brought in the last years important new insights into the friction between surfaces in relative motion and are of relevance for earthquakes, differing from classical block-spring models by the mechanism of energy input in the system. Robust nontrivial temporal scaling laws appearing in the dynamics of this system are reported, and it is shown that the time-support where dissipation occurs approaches a statistical fractal set with a fixed value of dimension. The distribution of periods of inactivity in the intermittent motion of the cylinder is also studied and found to be closely related to the lacunarity of a random version of the classic triadic Cantor set on the line.Comment: 7 pages including 6 figure

    Higher Derivative Corrections to Eleven Dimensional Supergravity via Local Supersymmetry

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    In this paper we derive higher derivative corrections to the eleven dimensional supergravity by applying the Noether method with respect to the N=1 local supersymmetry. An ansatz for the higher derivative effective action, which includes quartic terms of the Riemann tensor, is parametrized by 132 parameters. Then we show that by the requirement of the local supersymmetry, the higher derivative effective action is essentially described by two parameters. The bosonic parts of these two superinvariants completely match with the known results obtained by the perturbative calculations in the type IIA superstring theory. Since the calculations are long and systematic, we build the computer programming to check the cancellation of the variations under the local supersymmetry. This is an extended version of our previous paper hep-th/0508204.Comment: 67 pages, no figure, references added, typos correcte

    Limitations on the superposition principle: superselection rules in non-relativistic quantum mechanics

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    The superposition principle is a very basic ingredient of quantum theory. What may come as a surprise to many students, and even to many practitioners of the quantum craft, is tha superposition has limitations imposed by certain requirements of the theory. The discussion of such limitations arising from the so-called superselection rules is the main purpose of this paper. Some of their principal consequences are also discussed. The univalence, mass and particle number superselection rules of non-relativistic quantum mechanics are also derived using rather simple methods.Comment: 22 pages, no figure

    Produção de biomassa e teor de óleo essencial de plantas de óleo eletrico (Piper callosum Ruiz & Pav.) em diferentes níveis de luminosidade nas condições de Manaus-AM.

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    O presente trabalho visou mostrar efeitos de diferentes níveis de luminosidade na produção de biomassa, teor de óleo essencial de Piper callosum Ruiz & Pav. pertencente à família Piperaceae, conhecida vulgarmente como óleo elétrico e panquilé.Edição dos Resumos do 52º Congresso Brasileiro de Olericultura, Salvador, jul. 2012

    Produção de biomassa aérea de três morfotipos de crajiru [Arrabidaea chica (Bonpl.) B. Verl.] em função da adubação orgânica em Manaus, AM.

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    Este trabalho teve o objetivo de avaliar a produção de biomassa aérea em função de diferentes fontes de adubo orgânico em Manaus, AM.Edição dos Resumos do 52º Congresso Brasileiro de Olericultura, Salvador, jul. 2012
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