Squeezing and photon distribution in a vibrating cavity

We obtain explicit analytical expressions for the quadrature variances and the photon distribution functions of the electromagnetic field modes excited from vacuum or thermal states due to the non-stationary Casimir effect in an ideal one-dimensional Fabry--Perot cavity with vibrating walls, provided the frequency of vibrations is close to a multiple frequency of the fundamental unperturbed electromagnetic mode.Comment: 20 pages, LaTex2e, iopart document class, 2 ps figures, accepted for publication in J. Phys.

Exact propagators for atom-laser interactions

A class of exact propagators describing the interaction of an $N$-level atom with a set of on-resonance $\delta$-lasers is obtained by means of the Laplace transform method. State-selective mirrors are described in the limit of strong lasers. The ladder, V and $\Lambda$ configurations for a three-level atom are discussed. For the two level case, the transient effects arising as result of the interaction between both a semi-infinite beam and a wavepacket with the on-resonance laser are examined.Comment: 13 pages, 6 figure

Self-interference of a single Bose-Einstein condensate due to boundary effects

A simple model wavefunction, consisting of a linear combination of two free-particle Gaussians, describes many of the observed features seen in the interactions of two isolated Bose-Einstein condensates as they expand, overlap, and interfere. We show that a simple extension of this idea can be used to predict the qualitative time-development of a single expanding BEC condensate produced near an infinite wall boundary, giving similar interference phenomena. We also briefly discuss other possible time-dependent behaviors of single BEC condensates in restricted geometries,such as wave packet revivals.Comment: 8 pages, no figures, to appear in Physica Script

Exact closed form analytical solutions for vibrating cavities

For one-dimensional vibrating cavity systems appearing in the standard illustration of the dynamical Casimir effect, we propose an approach to the construction of exact closed-form solutions. As new results, we obtain solutions that are given for arbitrary frequencies, amplitudes and time regions. In a broad range of parameters, a vibrating cavity model exhibits the general property of exponential instability. Marginal behavior of the system manifests in a power-like growth of radiated energy.Comment: 17 pages, 7 figure

Biomarkers for Mercury Exposure in Tropical Estuarine Fish

Several studies have evaluated human risks due mercury (Hg) exposure through fish consumption. However, relatively few studies have explored effects of environmental Hg concentrations in biota, especially tropical fish species. The aim of this work was to assess in situ hematological, biochemical and genotoxic effects in tropical fish due to environmental exposure to mercury in estuarine ecosystems. A total of 282 fishes were collected from September 2003 to October 2005 in two estuarine areas: Ribeira Bay (reference area - 22° 55’ to 23° 02’ S and 44° 18’ to 44° 26’ W) and Guanabara Bay (highly impacted area by human activities - 22° 40’ to 23° 00’ S and 43° 00’ to 43° 20’ E). Total mercury levels in fish from Guanabara were twice higher than in Ribeira bay for the catfish species Genidens genidens (Ariidae), with significant differences among areas after standardization using length intervals (exposure time indicator). The species Haemulon steindachneri (Haemulidae) showed the highest mercury concentration, reflecting its position in trophic chain. Among effect biomarkers, only haematocrit, global leucometry and micronucleus assays seemed to reflect the differences on mercury exposure among areas, what may support their use for evaluations of fish exposure to mercury compounds. However, it’s necessary both laboratory experiments to establish cause-effect relationship and a continuous in situ study to obtain more information, involving more trophic levels, searching for sensible species to mercury exposure