Decoherence of Semiclassical Wigner Functions

The Lindblad equation governs general markovian evolution of the density operator in an open quantum system. An expression for the rate of change of the Wigner function as a sum of integrals is one of the forms of the Weyl representation for this equation. The semiclassical description of the Wigner function in terms of chords, each with its classically defined amplitude and phase, is thus inserted in the integrals, which leads to an explicit differential equation for the Wigner function. All the Lindblad operators are assumed to be represented by smooth phase space functions corresponding to classical variables. In the case that these are real, representing hermitian operators, the semiclassical Lindblad equation can be integrated. There results a simple extension of the unitary evolution of the semiclassical Wigner function, which does not affect the phase of each chord contribution, while dampening its amplitude. This decreases exponentially, as governed by the time integral of the square difference of the Lindblad functions along the classical trajectories of both tips of each chord. The decay of the amplitudes is shown to imply diffusion in energy for initial states that are nearly pure. Projecting the Wigner function onto an orthogonal position or momentum basis, the dampening of long chords emerges as the exponential decay of off-diagonal elements of the density matrix.Comment: 23 pg, 2 fi

Replica analysis of the generalized p-spin interaction glass model

We investigate stability of replica symmetry breaking solutions in generalized $p$-spin models. It is shown that the kind of the transition to the one-step replica symmetry breaking state depends not only on the presence or absence of the reflection symmetry of the generalized "spin"-operators $\hat{U}$ but on the number of interacting operators and their individual characteristics.Comment: 14 pages, 1 figur

Efeito da temperatura no crescimento de Xanthomonas axonopodis pv. passiflorae e Xanthomonas axonopodis pv. manihotis.

Bactérias do gênero Xanthomonas apresentam uma diversidade na gama de hospedeiros, causando sérios prejuízos em todas as regiões do Brasil. Xanthomonas axonopodis pv. passiflorae (Xap) e Xanthomonas axonopodis pv. manihotis (Xam) são responsáveis pelas bacterioses nas culturas do maracujá e da mandioca, respectivamente. O presente trabalho teve como objetivo avaliar o efeito de diferentes temperaturas sobre o crescimento de Xap e Xam. Foram avaliadas as temperaturas de 15ºC, 20ºC, 25ºC, 30ºC, 35°C e 40°C através da contagem de Unidades formadoras de colônia de patógeno após 48 horas de incubação. Para cada patógeno, o delineamento experimental foi inteiramente casualizado com 6 tratamentos e 10 repetições. Observou-se efeito da temperatura sobre o crescimento de ambas as bactérias fitopatogênicas, as quais cresceram no intervalo entre 25°C e 35°C. O crescimento bacteriano de ambos patógenos apresentou comportamento quadrático, sendo que os valores de temperatura ótima foram obtidos pela derivada da equação de regressão. O crescimento ótimo de Xap foi observado a 29,01°C, enquanto o de Xam foi observado a 28,38°C. Para os dois patógenos estudados não houve crescimento nas temperaturas de 15°C, 20°C e 40ºC

Sistemas de Integração lavoura-pecuária-floresta (iLPF)- Experiências no BRASIL.

Resumo: Os sistemas de integração lavoura-pecuária-floresta são sustentáveis e a escolha do sistema adequado à determinada localidade depende das condições edafo-climáticas e da existência de infraestrutura para suprimento de insumos, armazenagem e escoamento da produção. A produtividade e a rentabilidade são três vezes maiores para a pecuária de corte e de 10 a 30% para as lavouras de grãos em relação aos sistemas tradicionais de produção. Por outro lado, observa-se nos sistemas mais complexos (com uso de componente arbóreo) o aumento do bem-estar animal e a mitigação de gases de efeito estufa. [Systems integration crop-livestock-forest (ICLF) - Experiences in Brazil]. Abstract: The integrated crop-livestock-forest systems are sustainable and the choice of the appropriate system to a given locality depends on the soil and climatic conditions and the availability of infrastructure for input supply, storage and transportation of production. Productivity and profitability are three times higher for beef cattle and 10-30% for grain crops relative to traditional production systems. On the other hand it is observed in more complex systems (using the tree component) animal welfare increase and mitigation of greenhouse gases

Diluted antiferromagnet in a ferromagnetic enviroment

The question of robustness of a network under random ``attacks'' is treated in the framework of critical phenomena. The persistence of spontaneous magnetization of a ferromagnetic system to the random inclusion of antiferromagnetic interactions is investigated. After examing the static properties of the quenched version (in respect to the random antiferromagnetic interactions) of the model, the persistence of the magnetization is analysed also in the annealed approximation, and the difference in the results are discussed

Acute and chronic stress differentially regulate cyclin-dependent kinase 5 in mouse brain: implications to glucocorticoid actions and major depression

Stress activates the hypothalamic–pituitary–adrenal axis, which in turn increases circulating glucocorticoid concentrations and stimulates the glucocorticoid receptor (GR). Chronically elevated glucocorticoids by repetitive exposure to stress are implicated in major depression and anxiety disorders. Cyclin-dependent kinase 5 (CDK5), a molecule essential for nervous system development, function and pathogenesis of neurodegenerative disorders, can modulate GR activity through phosphorylation. We examined potential contribution of CDK5 to stress response and pathophysiology of major depression. In mice, acute immobilized stress (AS) caused a biphasic effect on CDK5 activity, initially reducing but increasing afterwards in prefrontal cortex (PFC) and hippocampus (HIPPO), whereas chronic unpredictable stress (CS) strongly increased it in these brain areas, indicating that AS and CS differentially regulate this kinase activity in a brain region-specific fashion. GR phosphorylation contemporaneously followed the observed changes of CDK5 activity after AS, thus CDK5 may in part alter GR phosphorylation upon this stress. In the postmortem brains of subjects with major depression, CDK5 activity was elevated in Brodmann's area 25, but not in entire PFC and HIPPO. Messenger RNA expression of glucocorticoid-regulated/stress-related genes showed distinct expression profiles in several brain areas of these stressed mice or depressive subjects in which CDK5-mediated changes in GR phosphorylation may have some regulatory roles. Taken together, these results indicate that CDK5 is an integral component of stress response and major depression with regulatory means specific to different stressors, brain areas and diseases in part through changing phosphorylation of GR

A typical reconstruction limit of compressed sensing based on Lp-norm minimization

We consider the problem of reconstructing an $N$-dimensional continuous vector \bx from $P$ constraints which are generated by its linear transformation under the assumption that the number of non-zero elements of \bx is typically limited to $\rho N$ ($0\le \rho \le 1$). Problems of this type can be solved by minimizing a cost function with respect to the $L_p$-norm ||\bx||_p=\lim_{\epsilon \to +0}\sum_{i=1}^N |x_i|^{p+\epsilon}, subject to the constraints under an appropriate condition. For several $p$, we assess a typical case limit $\alpha_c(\rho)$, which represents a critical relation between $\alpha=P/N$ and $\rho$ for successfully reconstructing the original vector by minimization for typical situations in the limit $N,P \to \infty$ with keeping $\alpha$ finite, utilizing the replica method. For $p=1$, $\alpha_c(\rho)$ is considerably smaller than its worst case counterpart, which has been rigorously derived by existing literature of information theory.Comment: 12 pages, 2 figure

On FO2 quantifier alternation over words

We show that each level of the quantifier alternation hierarchy within FO^2[<] -- the 2-variable fragment of the first order logic of order on words -- is a variety of languages. We then use the notion of condensed rankers, a refinement of the rankers defined by Weis and Immerman, to produce a decidable hierarchy of varieties which is interwoven with the quantifier alternation hierarchy -- and conjecturally equal to it. It follows that the latter hierarchy is decidable within one unit: given a formula alpha in FO^2[<], one can effectively compute an integer m such that alpha is equivalent to a formula with at most m+1 alternating blocks of quantifiers, but not to a formula with only m-1 blocks. This is a much more precise result than what is known about the quantifier alternation hierarchy within FO[<], where no decidability result is known beyond the very first levels