2,806 research outputs found
Certificação e selos de qualidade asseguram requisitos na produção.
Em 2011, o Committee on Fisheries (Cofi) da Food and Agriculture Organization (FAO) comitê de pesca da FAO, órgão da Organização das Nações Unidas (ONU) aprovou o documento que contém as Diretrizes Técnicas para Certificação da Aquicultura, visando ao desenvolvimento, à organização e à implementação de regimes confiáveis de certificação de aquicultura. Os países signatários deverão internalizá-lo e usá-lo como base para adaptar ou criar as normas relacionadas ao tema. O documento abrange questões de saúde e bem-estar animal, segurança alimentar, integridade ambiental e aspectos socioeconômicos
A model for the onset of transport in systems with distributed thresholds for conduction
We present a model supported by simulation to explain the effect of
temperature on the conduction threshold in disordered systems. Arrays with
randomly distributed local thresholds for conduction occur in systems ranging
from superconductors to metal nanocrystal arrays. Thermal fluctuations provide
the energy to overcome some of the local thresholds, effectively erasing them
as far as the global conduction threshold for the array is concerned. We
augment this thermal energy reasoning with percolation theory to predict the
temperature at which the global threshold reaches zero. We also study the
effect of capacitive nearest-neighbor interactions on the effective charging
energy. Finally, we present results from Monte Carlo simulations that find the
lowest-cost path across an array as a function of temperature. The main result
of the paper is the linear decrease of conduction threshold with increasing
temperature: , where is an
effective charging energy that depends on the particle radius and interparticle
distance, and is the percolation threshold of the underlying lattice. The
predictions of this theory compare well to experiments in one- and
two-dimensional systems.Comment: 14 pages, 10 figures, submitted to PR
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