Ecologia microbiana do solo.

Fatores abióticos que afetam os microrganismos; Temperatura do solo; pH do solo; Fontes de energia e substratos orgânicos; Nutrientes minerais; Práticas de manejo e cultivo dos solos; Interação entre microrganismos; Interações microbianas de importância para a produção agrícola.bitstream/item/35904/1/Doc164.pd

Invasion Percolation Between two Sites

We investigate the process of invasion percolation between two sites (injection and extraction sites) separated by a distance r in two-dimensional lattices of size L. Our results for the non-trapping invasion percolation model indicate that the statistics of the mass of invaded clusters is significantly dependent on the local occupation probability (pressure) Pe at the extraction site. For Pe=0, we show that the mass distribution of invaded clusters P(M) follows a power-law P(M) ~ M^{-\alpha} for intermediate values of the mass M, with an exponent \alpha=1.39. When the local pressure is set to Pe=Pc, where Pc corresponds to the site percolation threshold of the lattice topology, the distribution P(M) still displays a scaling region, but with an exponent \alpha=1.02. This last behavior is consistent with previous results for the cluster statistics in standard percolation. In spite of these discrepancies, the results of our simulations indicate that the fractal dimension of the invaded cluster does not depends significantly on the local pressure Pe and it is consistent with the fractal dimension values reported for standard invasion percolation. Finally, we perform extensive numerical simulations to determine the effect of the lattice borders on the statistics of the invaded clusters and also to characterize the self-organized critical behavior of the invasion percolation process.Comment: 7 pages, 11 figures, submited for PR

Temperature oscillations of magnetization observed in nanofluid ferromagnetic graphite

We report on unusual magnetic properties observed in the nanofluid room-temperature ferromagnetic graphite (with an average particle size of l=10nm). More precisely, the measured magnetization exhibits a low-temperature anomaly (attributed to manifestation of finite size effects below the quantum temperature) as well as pronounced temperature oscillations above T=50K (attributed to manifestation of the hard-sphere type pair correlations between ferromagnetic particles in the nanofluid)

Screening effects in flow through rough channels

A surprising similarity is found between the distribution of hydrodynamic stress on the wall of an irregular channel and the distribution of flux from a purely Laplacian field on the same geometry. This finding is a direct outcome from numerical simulations of the Navier-Stokes equations for flow at low Reynolds numbers in two-dimensional channels with rough walls presenting either deterministic or random self-similar geometries. For high Reynolds numbers, when inertial effects become relevant, the distribution of wall stresses on deterministic and random fractal rough channels becomes substantially dependent on the microscopic details of the walls geometry. In addition, we find that, while the permeability of the random channel follows the usual decrease with Reynolds, our results indicate an unexpected permeability increase for the deterministic case, i.e., ``the rougher the better''. We show that this complex behavior is closely related with the presence and relative intensity of recirculation zones in the reentrant regions of the rough channel.Comment: 4 pages, 5 figure

The role of cinema on the tourist destination image formation process

Tourism literature widely acknowledges that images of tourist destinations are a product of all the experiences of an individual, being influenced by a series of information sources. The movies figure amongst this sources, and as an autonomous information agent, which in theory are not associated with the tourist market interests, they transmit information that is perceived as more reliable than conventional publicity. Thus, cinema acts directly on the organic image, creating and perpetuating associations about the places it depicts on the collective imagery. The present article aims to provide a bibliographical state of the art about the influence of films on the tourist destinations’ image, contextualizing the cinema on it’s formation process, as well as the cognitive and phsycological processes involved

Caracterização de acessos de mandioca silvestre para uso no pré-melhoramento de Manihot esculenta Crantz.

As mandiocas silvestres exercem um papel inquestionável por serem considerados reservatórios de alelos competitivos e de interesse para uso dos melhoristas. O presente trabalho teve por objetivo dar início à caracterização molecular de 33 acessos de espécies silvestres de Manihot com o intuito de avaliar a variabilidade genética para ser explorada dentro do programa de melhoramento genético de mandioca da Embrapa Mandioca e Fruticultura. O DNA foi extraído dos acessos e será utilizado na etapa seguinte de caracterização molecular. Os dados obtidos serão analisados e submetidos à análise multivariada de agrupamento a partir da matriz do índice de dissimilaridade de Jaccard. A susceptibilidade ou incapacidade genética da mandioca só pode ser evitada com a variabilidade, na qual a mesma depende dos recursos genéticos. As espécies silvestres de Manihot são pouco estudadas e este trabalho servirá de base para o delineamento das estratégias de cruzamentos pelos melhoristas com o intuito de transferir genes de interesse para as espécies cultivadas