4,213 research outputs found
Importância da qualidade e certificação para ampliação do mercado internacional da manga brasileira.
Boas práticas agrícolas.
O presente trabalho tem por objetivo fornecer aos produtores informações úteis para a implementação das boas práticas agrícolas, necessárias para assegurar a inocuidade de frutas e hortaliças. Aos produtores nacionais que desejam entrar no mercado de exportação, recomenda-se adotar tais práticas de higiene que lhes darão a vantagem de poder exportar, sem correr o risco da recusa de seus produtos por problemas de contaminações biológicas, químicas ou físicas.bitstream/item/143305/1/ID-31375.pd
The importance of the Ising model
Understanding the relationship which integrable (solvable) models, all of
which possess very special symmetry properties, have with the generic
non-integrable models that are used to describe real experiments, which do not
have the symmetry properties, is one of the most fundamental open questions in
both statistical mechanics and quantum field theory. The importance of the
two-dimensional Ising model in a magnetic field is that it is the simplest
system where this relationship may be concretely studied. We here review the
advances made in this study, and concentrate on the magnetic susceptibility
which has revealed an unexpected natural boundary phenomenon. When this is
combined with the Fermionic representations of conformal characters, it is
suggested that the scaling theory, which smoothly connects the lattice with the
correlation length scale, may be incomplete for .Comment: 33 page
The saga of the Ising susceptibility
We review developments made since 1959 in the search for a closed form for
the susceptibility of the Ising model. The expressions for the form factors in
terms of the nome and the modulus are compared and contrasted. The
generalized correlations are defined and explicitly
computed in terms of theta functions for .Comment: 19 pages, 1 figur
Dynamic range of hypercubic stochastic excitable media
We study the response properties of d-dimensional hypercubic excitable
networks to a stochastic stimulus. Each site, modelled either by a three-state
stochastic susceptible-infected-recovered-susceptible system or by the
probabilistic Greenberg-Hastings cellular automaton, is continuously and
independently stimulated by an external Poisson rate h. The response function
(mean density of active sites rho versus h) is obtained via simulations (for
d=1, 2, 3, 4) and mean field approximations at the single-site and pair levels
(for all d). In any dimension, the dynamic range of the response function is
maximized precisely at the nonequilibrium phase transition to self-sustained
activity, in agreement with a reasoning recently proposed. Moreover, the
maximum dynamic range attained at a given dimension d is a decreasing function
of d.Comment: 7 pages, 4 figure
Poynting Vector Flow in a Circular Circuit
A circuit is considered in the shape of a ring, with a battery of negligible
size and a wire of uniform resistance. A linear charge distribution along the
wire maintains an electrostatic field and a steady current, which produces a
constant magnetic field. Earlier studies of the Poynting vector and the rate of
flow of energy considered only idealized geometries in which the Poynting
vector was confined to the space within the circuit. But in more realistic
cases the Poynting vector is nonzero outside as well as inside the circuit. An
expression is obtained for the Poynting vector in terms of products of
integrals, which are evaluated numerically to show the energy flow. Limiting
expressions are obtained analytically. It is shown that the total power
generated by the battery equals the energy flowing into the wire per unit time.Comment: 19 pages, 8 figure
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