12,986 research outputs found

    Influence of disordered porous media in the anomalous properties of a simple water model

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    The thermodynamic, dynamic and structural behavior of a water-like system confined in a matrix is analyzed for increasing confining geometries. The liquid is modeled by a two dimensional associating lattice gas model that exhibits density and diffusion anomalies, in similarity to the anomalies present in liquid water. The matrix is a triangular lattice in which fixed obstacles impose restrictions to the occupation of the particles. We show that obstacules shortens all lines, including the phase coexistence, the critical and the anomalous lines. The inclusion of a very dense matrix not only suppress the anomalies but also the liquid-liquid critical point

    INPE LANDSAT system

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    Anomalies in a waterlike model confined between plates

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    Using molecular dynamic simulations we study a waterlike model confined between two fixed hydrophobic plates. The system is tested for density, diffusion and structural anomalous behavior and compared with the bulk results. Within the range of confining distances we had explored we observe that in the pressure-temperature phase diagram the temperature of maximum density (TMD line), the temperature of maximum and minimum diffusion occur at lower temperatures when compared with the bulk values. For distances between the two layers below a certain threshold ,d≤dcd\le d_c, only two layers of particles are formed, for d≥dcd\ge d_c three or more layers are formed. In the case of three layers the central layer stays liquid while the contact layers crystallize. This result is in agreement with simulations for atomistic models

    A dissemination strategy for immunizing scale-free networks

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    We consider the problem of distributing a vaccine for immunizing a scale-free network against a given virus or worm. We introduce a new method, based on vaccine dissemination, that seems to reflect more accurately what is expected to occur in real-world networks. Also, since the dissemination is performed using only local information, the method can be easily employed in practice. Using a random-graph framework, we analyze our method both mathematically and by means of simulations. We demonstrate its efficacy regarding the trade-off between the expected number of nodes that receive the vaccine and the network's resulting vulnerability to develop an epidemic as the virus or worm attempts to infect one of its nodes. For some scenarios, the new method is seen to render the network practically invulnerable to attacks while requiring only a small fraction of the nodes to receive the vaccine

    Causas de variação do peso de vacas da raça Canchim criadas em regime de pastagens.

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    O objetivo do trabalho foi estimar os efeitos de fatores genético e ambientais no peso de vacas da raça Canchim, criadas em regime de pastagens na EMBRAPA-UEPAE, São Carlos, SP

    Fatores que influenciam os pesos de bezerros Canchim ao nascimento e a desmama.

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    Foram analisados os pesos ao nascimento a desmama de 1.404 bezerros Canchim, filhos de touros e nascidos durante o período de 1971 a 1979. Os pesos a desmama foram ajustados para 270 dias pelo ganho médio diário do nascimento e pela regressão do peso observado em função da idade da desmama
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