12,986 research outputs found
Influence of disordered porous media in the anomalous properties of a simple water model
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
Anomalies in a waterlike model confined between plates
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 ,, only two layers of particles are
formed, for 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
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.
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
Efeito bioestimulatório da presença do macho no intervalo parto-primeiro cio e na taxa de cio de vacas de corte.
Fatores que influenciam os pesos de bezerros Canchim ao nascimento e a desmama.
Foram analisados os pesos ao nascimento a desmama de 1.404 bezerros Canchim, filhos de touros e nascidos durante o perÃodo 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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