RESUMO
We investigate the effect of the node degree and energy E on the electronic wave function for regular and irregular structures, namely, regular lattices, disordered percolation clusters, and complex networks. We evaluate the dependency of the quantum probability for each site on its degree. For a class of biregular structures formed by two disjoint subsets of sites sharing the same degree, the probability P_{k}(E) of finding the electron on any site with k neighbors is independent of E≠0, a consequence of an exact analytical result that we prove for any bipartite lattice. For more general nonbipartite structures, P_{k}(E) may depend on E as illustrated by an exact evaluation of a one-dimensional semiregular lattice: P_{k}(E) is large for small values of E when k is also small, and its maximum values shift towards large values of |E| with increasing k. Numerical evaluations of P_{k}(E) for two different types of percolation clusters and the Apollonian network suggest that this observed feature might be generally valid.
RESUMO
Recent experimental advances have measured individual coin components in discrete time quantum walks, which have not received the due attention in most theoretical studies on the theme. Here is presented a detailed investigation of the properties of M, the difference between square modulus of coin states of discrete quantum walks on a linear chain. Local expectation values are obtained in terms of real and imaginary parts of the Fourier transformed wave function. A simple expression is found for the average difference between coin states in terms of an angle θ gauging the coin operator and its initial state. These results are corroborated by numerical integration of dynamical equations in real space. The local dependence is characterized both by large and short period modulations. The richness of revealed patterns suggests that the amount of information stored and retrieved from quantum walks is significantly enhanced if M is taken into account.
RESUMO
We use a cellular automaton traffic model in order to study a nonequilibrium phase transition. We define an order parameter and show that its conjugated field is a parameter of randomness of the model. We analyze the symmetries of the free (unbroken) and of the jammed (broken) phases. Our results are consistent with a second-order phase transition at p=0 . Nontrivial critical exponents have also been obtained.
RESUMO
Realizou-se estudo comparativo de diferentes sorotipos de Leptospira interrogans utilizados na preparacao de antigenos empregados no teste ELISA, para a deteccao de anticorpos da classe IgM, em amostras de soro na fase precoce e tardia da leptospirose humana. Foram utilizados dez sorotipos, escolhidos entre os que apresentaram maior reatividade na soroaglutinacao microscopica (SAM), na cidade de Sao Paulo. Os cinco sorotipos que apresentaram melhores resultados individualmente no teste ELISA-IgM (canicola, hebdomadis, icterohaemorrhagiae, cynopteri e brasiliensis), foram tambem estudados em mistura antigenica. Os antigenos nao tratados apresentaram maior reatividade do que os antigenos tratados com Triton X-100 (4 por cento) a temperatura de 50§C, durante 4 horas. O teste ELISA-IgM empregando os sorotipos nao tratados, isoladamente, e em mistura antigenica, mostrou-se altamente sensivel, podendo ser empregado como teste de triagem para o diagnostico precoce da leptospirose humana. Outra aplicacao do teste e permitir a deteccao do inicio de situacoes epidemicas ou de surtos, possibilitando acionar medidas de vigilancia epidemiologica
