Adiabatic elimination in quantum stochastic models

We consider a physical system with a coupling to bosonic reservoirs via a quantum stochastic differential equation. We study the limit of this model as the coupling strength tends to infinity. We show that in this limit the solution to the quantum stochastic differential equation converges strongly to the solution of a limit quantum stochastic differential equation. In the limiting dynamics the excited states are removed and the ground states couple directly to the reservoirs.Comment: 17 pages, no figures, corrected mistake

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

ASPECTOS DO ZOOPLÂNCTON DA BAÍA DE SEPETIBA (RJ, BRASIL).

Zooplankton and physico-chemical water parameters were studied in 12 stations of Sepetiba Bay from April to June 1990. The dominant zooplankton groups were Copepoda, Cladocera and Chaetognatha. Cluster and discriminant analysis showed the influence of western oceanic waters on the zooplanktonic community as well as industrial and domestic waste inputs on the east side of the bay. Detailed studies about zooplankton and ichthyoplankton seasonal variations and the influence of environmental variables on the planktonic community of Sepetiba Bay are recommended.A variação do zooplâncton e dos parâmetros físico-químicos da água foi estudada em 12 estações na baía de Sepetiba durante os meses de abril a junho de 1990. Os grupos mais abundantes foram os Copepoda, Cladocera e Chaetognatha. As análises de agrupamento e discriminante demonstraram, principalmente, a influência sobre a comunidade zooplanctônica de águas oceânicas à oeste, bem como dos efluentes industriais e domésticos, especialmente dos metais chumbo e zinco, à leste da baía. Estudos mais detalhados sobre as flutuações sazonais do zooplâncton e ictioplâncton e a influência das variáveis ambientais na dinâmica destas comuni­dades da baía de Sepetiba mostraram-se necessários

A search for charmed particles originating from the interactions of 300 GeV/c protons in emulsion nuclei

The associated production of charmed particles by the interactions of 300 GeV/c protons with complex nuclei has been sought using nuclear emulsions. The failure to observe any candidates for this process among some 60,000 interactions investigated implies, provided charmed particles lifetimes are in the range 10 -12 to 10 -14 s, a cross section for their associated production by the interactions of 300 GeV/c protons with nucleons of less than 1.5 microbarns at a 90% confidence level. © 1976.SCOPUS: ar.jinfo:eu-repo/semantics/publishe