Quantum phase space picture of Bose-Einstein Condensates in a double well: Proposals for creating macroscopic quantum superposition states and a study of quantum chaos

We present a quantum phase space model of Bose-Einstein condensate (BEC) in a double well potential. In a two-mode Fock-state analysis we examine the eigenvectors and eigenvalues and find that the energy correlation diagram indicates a transition from a delocalized to a fragmented regime. Phase space information is extracted from the stationary quantum states using the Husimi distribution function. It is shown that the quantum states are localized on the known classical phase space orbits of a nonrigid physical pendulum, and thus the novel phase space characteristics of a nonrigid physical pendulum such as the $\pi$ motions are seen to be a property of the exact quantum states. Low lying states are harmonic oscillator like libration states while the higher lying states are Schr\"odinger cat-like superpositions of two pendulum rotor states. To study the dynamics in phase space, a comparison is made between a displaced quantum wavepacket and the trajectories of a swarm of points in classical phase space. For a driven double well, it is shown that the classical chaotic dynamics is manifest in the dynamics of the quantum states pictured using the Husimi distribution. Phase space analogy also suggests that a $\pi$ phase displaced wavepacket put on the unstable fixed point on a separatrix will bifurcate to create a superposition of two pendulum rotor states - a Schr\"odinger cat state (number entangled state) for BEC. It is shown that the choice of initial barrier height and ramping, following a $\pi$ phase imprinting on the condensate, can be used to generate controlled entangled number states with tunable extremity and sharpness.Comment: revised version, 13 pages, 13 figure

Effectiveness of Dried Distillers Grains with Solubles as a Replacement for Oilseed Meal in Supplements for Cattle Consuming Poor Quality Forage

A two-year study was conducted at the South Dakota State University Southeast Research Farm in Beresford, SD, to determine the effects of feeding supplemental dried distillers grains with solubles (DDGS) on the performance of mid-gestation and non-gestating, non-lactating beef cows. Ninety-six gestating beef cows (initial BW = 1276.4 ± 22.2; initial BCS = 4.7 ± 0.09) and 96 non-gestating, non-lactating beef cows (initial BW = 1214.0 ± 20.8; initial BCS = 5.4 ± 0.10) were used for year 1 and year 2, respectively. Cows were stratified by weight and allocated to one of 15 pens. Pens were then randomly assigned to one of three treatment supplements: 1) sunflower meal (SFM), 2) a 50:50 combination of SFM and dried distillers grains plus solubles (COMB), or 3) dried distillers grains plus solubles (DDGS). Supplements were formulated to be isocaloric and isonitrogenous, but provide decreasing levels of degradable intake protein (DIP; 332.6, 256.5, 206.8 g/d year 1, 338.1, 284.9, 232.2 g/d year 2). All cows received a basal diet of ground corn stalks and were allowed ad libitum access to a salt-mineral block. Cows were fed treatment diets for 70 days. Weights were taken on day -1, 0, 35, 69, and 70. Body condition scores (BCS) were determined on day 0 and 70. Ultrasound fat dept was determined at the 12th rib and on the rump on day 0 and 70. Weight change tended (P \u3c 0.06) to be affected by a treatment by year interaction. In year 1, cows consuming the SFM supplement gained more weight than cows consuming any of the other treatments. However, in year two, gain was not affected by treatment. Treatment had no effect on BCS or ultrasound fat depth at the 12th rib or rump. Small and inconsistent differences in performance and the lack of differences in body condition between treatments suggest that DDGS can replace an oilseed meal in protein supplements without affecting animal performance. Supplementing DDGS as a sole protein source for cows consuming poor-quality forage is a viable management alternative for producers

Irreversible reorganization in a supercooled liquid originates from localised soft modes

The transition of a fluid to a rigid glass upon cooling is a common route of transformation from liquid to solid that embodies the most poorly understood features of both phases1,2,3. From the liquid perspective, the puzzle is to understand stress relaxation in the disordered state. From the perspective of solids, the challenge is to extend our description of structure and its mechanical consequences to materials without long range order. Using computer simulations, we show that the localized low frequency normal modes of a configuration in a supercooled liquid are causally correlated to the irreversible structural reorganization of the particles within that configuration. We also demonstrate that the spatial distribution of these soft local modes can persist in spite of significant particle reorganization. The consequence of these two results is that it is now feasible to construct a theory of relaxation length scales in glass-forming liquids without recourse to dynamics and to explicitly relate molecular properties to their collective relaxation.Comment: Published online: 20 July 2008 | doi:10.1038/nphys1025 Available from http://www.nature.com/nphys/journal/v4/n9/abs/nphys1025.htm

Phase engineering of controlled entangled number states in a single component Bose-Einstein condensate in a double well

We propose a model for the creation of entangled number states (Schr\"odinger cat states) of a Bose-Einstein condensate in a double well through simple phase engineering. We show that a $\pi$-phase imprinted condensate in a double-well evolves, with a simultaneous change of barrier height, to number states with well defined and controlled entanglement. The cat state generation is understood in terms of the underlying classical phase space dynamics of a $\pi$-phase displaced coherent state put at the hyperbolic fixed point of the separatrix of a physical pendulum. The extremity and sharpness of the final cat state is determined by the initial barrier height and the rate at which it is ramped during the evolution.Comment: 11 pages, 5 figures, Submitted to J. Phys. B (letter to the editor

La recherche en santé mondiale : recueil de cas

Version anglaise disponible dans la Bibliothèque numérique du CRDI : Global health research : caseboo

The complete genome sequence and comparative genome analysis of the high pathogenicity Yersinia enterocolitica strain 8081

The human enteropathogen, Yersinia enterocolitica, is a significant link in the range of Yersinia pathologies extending from mild gastroenteritis to bubonic plague. Comparison at the genomic level is a key step in our understanding of the genetic basis for this pathogenicity spectrum. Here we report the genome of Y. enterocolitica strain 8081 (serotype 0:8; biotype 1B) and extensive microarray data relating to the genetic diversity of the Y. enterocolitica species. Our analysis reveals that the genome of Y. enterocolitica strain 8081 is a patchwork of horizontally acquired genetic loci, including a plasticity zone of 199 kb containing an extraordinarily high density of virulence genes. Microarray analysis has provided insights into species-specific Y. enterocolitica gene functions and the intraspecies differences between the high, low, and nonpathogenic Y. enterocolitica biotypes. Through comparative genome sequence analysis we provide new information on the evolution of the Yersinia. We identify numerous loci that represent ancestral clusters of genes potentially important in enteric survival and pathogenesis, which have been lost or are in the process of being lost, in the other sequenced Yersinia lineages. Our analysis also highlights large metabolic operons in Y. enterocolitica that are absent in the related enteropathogen, Yersinia pseudotuberculosis, indicating major differences in niche and nutrients used within the mammalian gut. These include clusters directing, the production of hydrogenases, tetrathionate respiration, cobalamin synthesis, and propanediol utilisation. Along with ancestral gene clusters, the genome of Y. enterocolitica has revealed species-specific and enteropathogen-specific loci. This has provided important insights into the pathology of this bacterium and, more broadly, into the evolution of the genus. Moreover, wider investigations looking at the patterns of gene loss and gain in the Yersinia have highlighted common themes in the genome evolution of other human enteropathogens