Procedimento de operação, manutenção e verificação da centrífuga SORVALL.

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Procedimento de operação, manutenção e verificação de acelerador de partículas.

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Quantum Correlations and Coherence in Spin-1 Heisenberg Chains

We explore quantum and classical correlations along with coherence in the ground states of spin-1 Heisenberg chains, namely the one-dimensional XXZ model and the one-dimensional bilinear biquadratic model, with the techniques of density matrix renormalization group theory. Exploiting the tools of quantum information theory, that is, by studying quantum discord, quantum mutual information and three recently introduced coherence measures in the reduced density matrix of two nearest neighbor spins in the bulk, we investigate the quantum phase transitions and special symmetry points in these models. We point out the relative strengths and weaknesses of correlation and coherence measures as figures of merit to witness the quantum phase transitions and symmetry points in the considered spin-1 Heisenberg chains. In particular, we demonstrate that as none of the studied measures can detect the infinite order Kosterlitz-Thouless transition in the XXZ model, they appear to be able to signal the existence of the same type of transition in the biliear biquadratic model. However, we argue that what is actually detected by the measures here is the SU(3) symmetry point of the model rather than the infinite order quantum phase transition. Moreover, we show in the XXZ model that examining even single site coherence can be sufficient to spotlight the second-order phase transition and the SU(2) symmetry point.Comment: 8 pages. 5 figure

Integral equation approach to tropical ocean dynamics: Part I-Theory and computational methods

In linear, three-dimensional, continuously stratified equatorial β-plane ocean models with arbitrary eastern and western boundaries the shallow water equations for each vertical mode must be solved numerically in the horizontal variables. This paper introduces a new numerical method of solution for the time-Fourier transformed shallow water equations with slip boundary conditions at boundaries of arbitrary geometry. The method is based on a boundary integral equation (BIE) for the pressure perturbation response to the specified wind-stress forcing field. All other dependent variables are expressed as boundary functionals of the pressure perturbation. The kernels of all functionals are constructed from the Green\u27s function for the Laplace Tidal Equation on the β-plane and its derivatives. The efficient computation of these kernels from their exact meridional mode representations may be performed by use of asymptotic methods especially developed for the numerical evaluation of functions expressed as slowly converging series of Hermite functions. The solution of the basic BIE and the computation of the boundary functionals involve the discretization of the ocean boundaries into a number of boundary segments (boundary elements). It is shown that the terms of the BIE involving the wind-stress field over the ocean may be reduced to a boundary integral, which effectively reduces the simulation problem to the solution of a one-dimensional BIE. The method incorporates the ocean physics through the relationship between the coastal pressure field and the basin-wide variables, pointing out to the possibility that the dynamic topography of the ocean may be estimated directly from the wind-stress field and coastal sea-level data

Integral equation approach to tropical ocean dynamics: Part II-Rossby wave scattering from the equatorial Atlantic western boundary

We develop a linear theory for the scattering of equatorial waves of a fixed frequency ω by islands and continental margins of arbitrary geometry by use of the boundary integral equation (BIE) method of Vianna and Holvorcem (Part I of this work). All the solutions of the equatorial β-plane dispersion relations at frequency ω are treated explicitly through the extensive use of exact Green\u27s functions, so that the approach is more general and more rigorous than previous attempts to solve equatorial scattering problems, many of which employ the low-frequency and long-wave approximations. The numerical solution of the HIE is obtained through application of the boundary element method. A numerical study of the scattering of Rossby waves with periods between 50 and 90 days from the equatorial Atlantic western boundary is presented. Some of the resulting interference patterns exhibit a sharp amplitude maximum, whose center lies between 3-9N, 35-47W. The position, width and intensity of this maximum all depend on wave period. We find evidences that this maximum arises from the superposition of zonally damped equatorial modes (evanescent waves) excited at the western boundary. The largest pressure amplitudes along the boundary are found in the southern hemisphere between the Equator and 5S. The phase propagation along the boundary is generally northwestward, except at a few positions where the phase is stationary. We discuss similarities and differences between the calculated responses and observations of intraseasonal oscillations in the tropical Atlantic Ocean

Cenários futuros para cana-de-açucar no Estado de São Paulo.

Com a atual contribuição econômica e tecnológica alcançada pelo setor canavieiro no Brasil é de altíssima importância a preocupação sobre os cenários futuros na agricultura e avaliação do impacto gerado pelas mudanças climáticas. Sobre a vulnerabilidade dos sistemas agrícolas, conseqüentemente, torna se de grande utilidade para o planejamento de médio e longo prazo do setor no País, adaptando-se aos possíveis impactos e observando as diferenças regionais quanto aos efeitos da mudança no clima. Portanto a necessidade de estudos com modelagem e análise de dados visando à avaliação dos possíveis impactos das mudanças climáticas sobre atividades humanas, recursos naturais e, particularmente, sobre a agricultura brasileira contém enormes valores econômicos e sociais com grande potencial de impacto no desenvolvimento nacional.Trabalho apresentado na V Mostra de Trabalhos de Estagiários e Bolsistas, Campinas, out. 2009