Superscars in the LiNC=LiCN isomerization reaction

We demonstrate the existence of superscarring in the LiNC=LiCN isomerization reaction described by a realistic potential interaction in the range of readily attainable experimental energies. This phenomenon arises as the effect of two periodic orbits appearing "out of the blue"in a saddle--node bifurcation taking place in the dynamics of the system. Potential practical consequences of this superlocalization in the corresponding wave functions are also considered.Comment: 6 pages, 5 figures. to appear in EP

The Network of Epicenters of the Olami-Feder-Christensen Model of Earthquakes

We study the dynamics of the Olami-Feder-Christensen (OFC) model of earthquakes, focusing on the behavior of sequences of epicenters regarded as a growing complex network. Besides making a detailed and quantitative study of the effects of the borders (the occurrence of epicenters is dominated by a strong border effect which does not scale with system size), we examine the degree distribution and the degree correlation of the graph. We detect sharp differences between the conservative and nonconservative regimes of the model. Removing border effects, the conservative regime exhibits a Poisson-like degree statistics and is uncorrelated, while the nonconservative has a broad power-law-like distribution of degrees (if the smallest events are ignored), which reproduces the observed behavior of real earthquakes. In this regime the graph has also a unusually strong degree correlation among the vertices with higher degree, which is the result of the existence of temporary attractors for the dynamics: as the system evolves, the epicenters concentrate increasingly on fewer sites, exhibiting strong synchronization, but eventually spread again over the lattice after a series of sufficiently large earthquakes. We propose an analytical description of the dynamics of this growing network, considering a Markov process network with hidden variables, which is able to account for the mentioned properties.Comment: 9 pages, 10 figures. Smaller number of figures, and minor text corrections and modifications. For version with full resolution images see http://fig.if.usp.br/~tpeixoto/cond-mat-0602244.pd

Projeto-piloto de promoção comercial de frutas da produção integrada: fundamentos e resultados.

bitstream/item/59966/1/CNPUV-CIR.TEC.-80-08.pd

Curso diário de parâmetros do estado hídrico do pinhão-manso (Jatropha curcas L.) no período chuvoso do município de Teresina, Piauí.

As mudanças climáticas globais, especialmente o aquecimento global oriundo da geração e emissão antrópica dos gases do efeito estufa, tem incentivado a substituição dos combustíveis fosseis por biocombustíveis como o biodiesel, mas sua produção nos volumes necessários dependera do aumento da oferta de óleos, exigindo do setor de ciência, tecnologia e inovação alternativas tecnológicas para a exploração de espécies vegetais oleaginosas de alta produtividade de óleo..

Stochastic stabilization of cosmological photons

The stability of photon trajectories in models of the Universe that have constant spatial curvature is determined by the sign of the curvature: they are exponentially unstable if the curvature is negative and stable if it is positive or zero. We demonstrate that random fluctuations in the curvature provide an additional stabilizing mechanism. This mechanism is analogous to the one responsible for stabilizing the stochastic Kapitsa pendulum. When the mean curvature is negative it is capable of stabilizing the photon trajectories; when the mean curvature is zero or positive it determines the characteristic frequency with which neighbouring trajectories oscillate about each other. In constant negative curvature models of the Universe that have compact topology, exponential instability implies chaos (e.g. mixing) in the photon dynamics. We discuss some consequences of stochastic stabilization in this context.Comment: 4 pages, 3 postscript figures in color which are also appropriate for black and white printers; v2 emphasizes relevance to flat as well as negatively curved cosmologies; to appear in J. Phys.

Performance and challenges in the value chain of the Anadara tuberculosa bivalve mollusk in Ecuador

The bivalve mollusk, Anadara tuberculosa (Black Shell, in Spanish Concha Prieta), is found on America’s Pacific coast, where it is harvested for subsistence and commercial markets. This paper aims to diagnose the performance of the black shell’s value chain. We also identify several challenges that must be addressed to improve the sustainability of the black shell fishery in Ecuador. The applied methodology was quantitative and descriptive. Its design was non-experimental, field, cross-sectional and ex post facto. The investigation was carried out from January to October 2019 in the Jambelí archipelago, El Oro province, Ecuador. The study population consisted of 565 individuals, shellfish collectors, shellfish associations managers, traders, and restaurants from the A. tuberculosa production chain. The sample size was estimated at 222 informants. The type of sampling used was probabilistic, random, stratified, and with proportional allocation, with an effective participation rate of those selected of approximately 80%. The questionnaire was applied personally through the structured survey method, in writing, in the work area, and with their consent. The performance of the value chain was diagnosed in the dimensions of productivity, competitiveness, and quality of life, reaching a 75.1% index, a result that indicates that the value chain has a moderate to good performance level. The competitiveness dimension reached the highest performance, followed by productivity. Quality of life was the dimension with the lowest performance. The value chain can be improved if the following challenges are met: (1) Restoration of the mangrove ecosystem, (2) Promotion of low-intensity shellfish aquaculture, (3) Good sanitary management and purification, (4) Promotion of value-focused ventures, (5) Strengthening of organizations and agreements for the use and custody of mangroves, and (6) Strengthening of institutions that contribute to the advancement of these challenge