Navegando por Autor "TAVARES, Maria Regina Madruga"

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Acesso aberto (Open Access)
Densidade crítica no modelo de percolação em rede de Bethe não-homogênea
(Sociedade Brasileira de Matemática Aplicada e Computacional, 2015-08) TAVARES, Héliton Ribeiro; SOUZA, Raimundo Nonato Carneiro de; TAVARES, Maria Regina Madruga; FARIAS, Valcir Joao da Cunha
In this work we deal with an inhomogeneous Bethe lattice percolation model where the probability of an edge in level n is open changes according as n. This model can be appropriate to the case where the media changes its density in a systematic way, such as the proliferation of insects that depends on the temperature and humidity, which fluctuates between day and night. We consider the case where the density p(·) follows a function of the distance l(.) from the origin, given by a sinusoid function p(·) = p + (1 - p)|sin(l(.))|. For this model we present results of Monte-Carlo simulation showing the behavior of the probability of percolation with a second-order phase transition, but we present too a formal proof that the density is non trivial, with the mathematical expression to compute the percolation threshold.
Acesso aberto (Open Access)
Modelo de efeitos fixos com medida repetida aplicado em experimentos de melhoramento genético do cupuaçuzeiro
(Universidade Federal do Pará, 2015-12) ALVES, Rafael Moysés; TAVARES, Maria Regina Madruga; TAVARES, Héliton Ribeiro; LOBATO, Tarcísio da Costa; OLIVEIRA, Terezinha Ferreira de
This study was conducted to evaluate vegetative performance of cupuassu progenies, in the immaturity phase, through analysis of repeated measures. The experimental area was installed in the municipality of Tomé Açu, Northeast of the state of Para. We employed 25 full-sib progeny of cupuassu, who had vegetative growth (height and diameter of the plant), monitored for three years. Because of the nature of longitudinal observations it was assessed primarily through Mauchly sphericity test, which type of statistical analysis should be applied. For the variable diameter, sphericity condition was not violated, therefore, proceeded to review the design scheme of split plot. For the height variable, the test was significant, indicating necessarily evaluate the best structure to explain the correlation of errors, being chosen the covariance structure Heterogeneous Composed Symmetry. Differences were found between the progenies only in the third year of evaluation, and the variable diameter of the plant allowed better discriminate the progenies.