Correlation functions of scattering matrix elements in microwave cavities with strong absorption

The scattering matrix was measured for microwave cavities with two antennas. It was analyzed in the regime of overlapping resonances. The theoretical description in terms of a statistical scattering matrix and the rescaled Breit-Wigner approximation has been applied to this regime. The experimental results for the auto-correlation function show that the absorption in the cavity walls yields an exponential decay. This behavior can only be modeled using a large number of weakly coupled channels. In comparison to the auto-correlation functions, the cross-correlation functions of the diagonal S-matrix elements display a more pronounced difference between regular and chaotic systems

Quantum Graphs: A simple model for Chaotic Scattering

We connect quantum graphs with infinite leads, and turn them to scattering systems. We show that they display all the features which characterize quantum scattering systems with an underlying classical chaotic dynamics: typical poles, delay time and conductance distributions, Ericson fluctuations, and when considered statistically, the ensemble of scattering matrices reproduce quite well the predictions of appropriately defined Random Matrix ensembles. The underlying classical dynamics can be defined, and it provides important parameters which are needed for the quantum theory. In particular, we derive exact expressions for the scattering matrix, and an exact trace formula for the density of resonances, in terms of classical orbits, analogous to the semiclassical theory of chaotic scattering. We use this in order to investigate the origin of the connection between Random Matrix Theory and the underlying classical chaotic dynamics. Being an exact theory, and due to its relative simplicity, it offers new insights into this problem which is at the fore-front of the research in chaotic scattering and related fields.Comment: 28 pages, 13 figures, submitted to J. Phys. A Special Issue -- Random Matrix Theor

Signatures of the correlation hole in total and partial cross sections

In a complex scattering system with few open channels, say a quantum dot with leads, the correlation properties of the poles of the scattering matrix are most directly related to the internal dynamics of the system. We may ask how to extract these properties from an analysis of cross sections. In general this is very difficult, if we leave the domain of isolated resonances. We propose to consider the cross correlation function of two different elastic or total cross sections. For these we can show numerically and to some extent also analytically a significant dependence on the correlations between the scattering poles. The difference between uncorrelated and strongly correlated poles is clearly visible, even for strongly overlapping resonances.Comment: 25 pages, 13 Postscript figures, typos corrected and references adde

Parasitismo em aves silvestres residentes e migratórias da Ilha da Marambaia, Estado do Rio de Janeiro1

RESUMO: O objetivo desta pesquisa foi buscar a presença de microrganismos em esfregaços sanguíneos de aves silvestres residentes ou migratórias da Ilha da Marambaia, município de Mangaratiba, estado do Rio de Janeiro, durante o ano de 2009. Para execução da pesquisa, 86 indivíduos referentes a 22 espécies foram capturados através de rede de neblina e após manuseio liberados ao seu habitat natural. Foi coletado sangue periférico das aves e realizado esfregaços sanguíneos. Como resultados foi diagnosticado a ocorrência de 11 (12,80%) indivíduos positivos para Plasmodium sp., um (1,16%) para microfilária e 16 (18,60%) para Borrelia sp. Foram encontrados carrapatos Amblyomma sp. (Família Ixodidae) parasitando as aves amostradas, o que sugere existir uma interação parasito-vetor-hospedeiro entre esse e o gênero Borrelia. Este estudo deve ser ampliado para outras regiões e o seu conhecimento dará maiores subsídios para outras pesquisas, voltadas principalmente para a preservação de aves em ambiente por elas escolhidos como seu habitat

Molecular identification of Isospora coerebae Berto, Flausino, Luz, Ferreira & Lopes, 2010 (Chromista: Miozoa: Eimeriidae) from the bananaquit Coereba flaveola (Linnaeus, 1758) (Passeriformes: Thraupidae: Coerebinae) from Brazil

Ortúzar-Ferreira, Carlos Nei, Andrade, Lucas De Assis S., Genovezoliveira, Jhon Lennon, Oliveira, Mariana S., Mello, Ericson R., Cardozo, Sergian V., Oliveira, Águida A., Lima, Viviane M., Ferreira, Ildemar, Berto, Bruno P. (2022): Molecular identification of Isospora coerebae Berto, Flausino, Luz, Ferreira & Lopes, 2010 (Chromista: Miozoa: Eimeriidae) from the bananaquit Coereba flaveola (Linnaeus, 1758) (Passeriformes: Thraupidae: Coerebinae) from Brazil. Zootaxa 5168 (1): 83-91, DOI: https://doi.org/10.11646/zootaxa.5168.1.