Recoherence in the entanglement dynamics and classical orbits in the N-atom Jaynes-Cummings model

The rise in linear entropy of a subsystem in the N-atom Jaynes-Cummings model is shown to be strongly influenced by the shape of the classical orbits of the underlying classical phase space: we find a one-to-one correspondence between maxima (minima) of the linear entropy and maxima (minima) of the expectation value of atomic excitation J_z. Since the expectation value of this operator can be viewed as related to the orbit radius in the classical phase space projection associated to the atomic degree of freedom, the proximity of the quantum wave packet to this atomic phase space borderline produces a maximum rate of entanglement. The consequence of this fact for initial conditions centered at periodic orbits in regular regions is a clear periodic recoherence. For chaotic situations the same phenomenon (proximity of the atomic phase space borderline) is in general responsible for oscillations in the entanglement properties.Comment: 15 pages (text), 6 figures; to be published in Physical Review

Circulating tumor cells in breast cancer: A tool whose time has come of age

Circulating tumor cells (CTCs) are isolated tumor cells disseminated from the site of disease in metastatic and/or primary cancers, including breast cancer, that can be identified and measured in the peripheral blood of patients. As recent technical advances have rendered it easier to reproducibly and repeatedly sample this population of cells with a high degree of accuracy, these cells represent an attractive surrogate marker of the site of disease

Piscina y gimnasio olímpico

Both buildings have a rectangular prismatic shape, and are surrounded by extensive car parks, where 1.080 cars can be accommodated. To cover the area, which is 111.90 by 101.60 m in plan area, and the gymnasium, which is 78.70 by 76.20 m, a double curvature suspended roof has been provided, avoiding the need of any columns. Work was begum in March 1967, and the site is 9.2 km from the Olympic Village and 9.8 km from the Plaza Mayor.Ambos volúmenes presentan una forma de prisma rectangular y están circundados por amplios estacionamientos, con capacidad para 1.080 automóviles. Para cubrir la Piscina de 111,90 x 101,60, y el Gimnasio, de 78,70 x 76,20, se ha diseñado un tipo de cubierta colgante de doble curvatura, evitando así columnas intermedias. Las obras se iniciaron en marzo de 1967, y están situadas a 9,2 km de la Villa Olímpica y a 9,8 km de la Plaza Mayor

Effect of Membrane Structure on the Action of Polyenes: I. Nystatin Action in Cholesterol- and Ergosterol-Containing Membranes

A detailed and thorough characterization of nystatin-induced permeability on lipid bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)-containing ergosterol or cholesterol is presented. The results show that the same collection of transmembrane pores appears in membranes containing either sterol. The concentration range for the appearance of these pores is sterol-dependent. Another mechanism of action, membrane disruption, is also observed in ergosterol-POPC membranes. The greater potency of nystatin present in ergosterol-containing membranes cannot be explained simply by the longer opening times of its pores, as has been suggeste

litter and soil arthropods diversity and density in a tropical dry forest ecosystem in western mexico

The composition and temporal changes of edaphic microarthropods in both litter layer and soil were analyzed in a tropical dry forest ecosystem in Western Mexico. Sampling was carried out from June 1991 to July 1992 in two small watersheds at the Chamela Biological Station (Jalisco State, Mexico). At each watershed 10 random cores samples, 11 cm in diameter and 5 cm depth, were taken monthly from each biotope from an area of 100 m(2) supercript stop. Fauna was extracted by Berlese-Tullgren funnels and preserved in 75% ethanol. The total abundance of arthropods was 96,338 specimens, belonging to 33 taxa. Numerically dominant groups were Prostigmata, Cryptostigmata, Collembola and Mesostigmata, which constituted 92.6% of the total abundance. The effect of current monthly precipitation and temperature on density of total Arthropoda and different Orders was also investigated. Precipitation and temperature were significantly correlated with Collembola and Mesostigmata densities and also with total arthropod. The seasonal variation in the amount of litterfall was also significantly related to the abundance of arthropod in the litter layer biotope