Quadratic-nonlinear Landau-Zener transition for association of an atomic Bose-Einstein condensate with inter-particle elastic interactions included

We study the strong coupling limit of a quadratic-nonlinear Landau-Zener problem for coherent photo- and magneto-association of cold atoms taking into account the atom-atom, atom-molecule, and molecule-molecule elastic scattering. Using an exact third-order nonlinear differential equation for the molecular state probability, we develop a variational approach which enables us to construct a highly accurate and simple analytic approximation describing the time dynamics of the coupled atom-molecule system. We show that the approximation describing time evolution of the molecular state probability can be written as a sum of two distinct terms; the first one, being a solution to a limit first-order nonlinear equation, effectively describes the process of the molecule formation while the second one, being a scaled solution to the linear Landau-Zener problem (but now with negative effective Landau-Zener parameter as long as the strong coupling regime is considered), corresponds to the remaining oscillations which come up when the process of molecule formation is over.Comment: 19 pages, 7 figures, accepted for publication in Eur. Phys. J.

Methods to evaluate fish freshness in research and industry

Current work in a European concerted action project ‘Evaluation of Fish Freshness’ (AIR3 CT94-2283) focuses on harmonizing research activities in the area of fish freshness evaluation in leading fish laboratories in Europe (see Box 1). The overall aim of the concerted action project is to validate methods for the assessment of fish freshness and to discuss the freshness criteria for fish commercialized within the European Union. The project\u27s participants are working in subgroups studying sensory analysis, microbiology, volatile compounds, proteins, lipids, adenosine triphosphate and physical measurements with respect to fish freshness evaluation. In this article, the different subgroups have summarized changes that occur in fish and methods to evaluate fish freshness as a first step towards the definition of criteria for fish freshness