A nonadiabatic semi-classical method for dynamics of atoms in optical lattices

We develop a semi-classical method to simulate the motion of atoms in a dissipative optical lattice. Our method treats the internal states of the atom quantum mechanically, including all nonadiabatic couplings, while position and momentum are treated as classical variables. We test our method in the one-dimensional case. Excellent agreement with fully quantum mechanical simulations is found. Our results are much more accurate than those of earlier semi-classical methods based on the adiabatic approximation.Comment: 7 pages, 5 figures, submitted to European Physical Journal

All in it together? The effects of recession on population health and health inequalities in England and Sweden, 1991 to 2010

This article is the first to comparatively examine the effects of two recessions on population health and health inequalities in the two historically contrasting welfare states of England and Sweden. Data from 1991–2010 on self-reported general health, age, gender, and educational status were obtained from the Health Survey for England, the Swedish Survey of Living Conditions, and the European Union Survey of Income and Living Conditions, for individuals aged over 16. Generalized linear models were used to test the effects of recessions on self-reported health and educational inequalities in health. Overall, recessions had a significant positive effect on the health of women—but not men—in both England (4%) and Sweden (7%). In England, this improvement was only enjoyed by the most educated women, with the health of less educated women declining during recession. In contrast, in Sweden, the health of all women improved significantly during recession regardless of their educational status, although the most educated benefitted the most. Relative educational inequalities in self-reported health therefore increased during recessions in both countries by 14 percent (England) and 17 percent (Sweden) but for different reasons. This study suggests that Sweden's welfare state protects the health of all during recessions

Demonstration of a controllable three-dimensional Brownian motor in symmetric potentials

We demonstrate a Brownian motor, based on cold atoms in optical lattices, where isotropic random fluctuations are rectified in order to induce controlled atomic motion in arbitrary directions. In contrast to earlier demonstrations of ratchet effects, our Brownian motor operates in potentials that are spatially and temporally symmetric, but where spatiotemporal symmetry is broken by a phase shift between the potentials and asymmetric transfer rates between them. The Brownian motor is demonstrated in three dimensions and the noise-induced drift is controllable in our system.Comment: 5 pages, 4 figure

Influence of the lattice topography on a three-dimensional, controllable Brownian motor

We study the influence of the lattice topography and the coupling between motion in different directions, for a three-dimensional Brownian motor based on cold atoms in a double optical lattice. Due to controllable relative spatial phases between the lattices, our Brownian motor can induce drifts in arbitrary directions. Since the lattices couple the different directions, the relation between the phase shifts and the directionality of the induced drift is non trivial. Here is therefore this relation investigated experimentally by systematically varying the relative spatial phase in two dimensions, while monitoring the vertically induced drift and the temperature. A relative spatial phase range of 2pi x 2pi is covered. We show that a drift, controllable both in speed and direction, can be achieved, by varying the phase both parallel and perpendicular to the direction of the measured induced drift. The experimental results are qualitatively reproduced by numerical simulations of a simplified, classical model of the system

Doping Dependence of the Electronic Structure of Ba_{1-x}K_{x}BiO_{3} Studied by X-Ray Absorption Spectroscopy

We have performed x-ray absorption spectroscopy (XAS) and x-ray photoemission spectroscopy (XPS) studies of single crystal Ba_{1-x}K_{x}BiO_{3} (BKBO) covering the whole composition range $0 \leq x \leq 0.60$. Several features in the oxygen 1\textit{s} core XAS spectra show systematic changes with $x$. Spectral weight around the absorption threshold increases with hole doping and shows a finite jump between $x=0.30$ and 0.40, which signals the metal-insulator transition. We have compared the obtained results with band-structure calculations. Comparison with the XAS results of BaPb_{1-x}Bi_{x}O_{3} has revealed quite different doping dependences between BKBO and BPBO. We have also observed systematic core-level shifts in the XPS spectra as well as in the XAS threshold as functions of $x$, which can be attributed to a chemical potential shift accompanying the hole doping. The observed chemical potential shift is found to be slower than that predicted by the rigid band model based on the band-structure calculations.Comment: 8 pages, 8 figures include

Sliding and abrasive wear behaviour of HVOF- and HVAF-sprayed Cr3C2-NiCr hardmetal coatings

This paper provides a comprehensive characterisation of HVOF- and HVAF-sprayed Cr3C2-25 wt.% NiCr hardmetal coatings. One commercial powder composition with two different particle size distributions was processed using five HVOF and HVAF thermal spray systems. All coatings contain less Cr3C2 than the feedstock powder, possibly due to the rebound of some Cr3C2-rich particles during high-velocity impact onto the substrate. Dry sand-rubber wheel abrasive wear testing causes both grooving and pull-out of splat fragments. Mass losses depend on inter- and intra-lamellar cohesion, being higher (≥70 mg after a wear distance of 5904 m) for the coatings deposited with the coarser feedstock powder or with one type of HVAF torch. Sliding wear at room temperature against alumina involves shallower abrasive grooving, small-scale delamination and carbide pull-outs, and it is controlled by intra-lamellar cohesion. The coatings obtained from the fine feedstock powder exhibit the lowest wear rates (≈5×10-6 mm3/(Nm)). At 400 °C, abrasive grooving dominates the sliding wear behaviour; wear rates increase by one order of magnitude but friction coefficients decrease from ≈0.7 to ≈0.5. The thermal expansion coefficient of the coatings (11.08×10-6 °C-1 in the 30-400 °C range) is sufficiently close to that of the steel substrate (14.23×10-6 °C-1) to avoid macro-cracking

A Fermi Surface study of Ba1−x_{1-x}Kx_{x}BiO3_{3}

We present all electron computations of the 3D Fermi surfaces (FS's) in Ba$_{1-x}$K$_{x}$BiO$_{3}$ for a number of different compositions based on the selfconsistent Korringa-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) approach for incorporating the effects of Ba/K substitution. By assuming a simple cubic structure throughout the composition range, the evolution of the nesting and other features of the FS of the underlying pristine phase is correlated with the onset of various structural transitions with K doping. A parameterized scheme for obtaining an accurate 3D map of the FS in Ba$_{1-x}$K$_{x}$BiO$_{3}$ for an arbitrary doping level is developed. We remark on the puzzling differences between the phase diagrams of Ba$_{1-x}$K$_{x}$BiO$_{3}$ and BaPb$_{x}$Bi$_{1-x}$O$_{3}$ by comparing aspects of their electronic structures and those of the end compounds BaBiO$_{3}$, KBiO$_3$ and BaPbO$_3$. Our theoretically predicted FS's in the cubic phase are relevant for analyzing high-resolution Compton scattering and positron-annihilation experiments sensitive to the electron momentum density, and are thus amenable to substantial experimental verification.Comment: 12 pages, 7 figures, to appear in Phys. Rev.

Evidence That Lipopolisaccharide May Contribute to the Cytokine Storm and Cellular Activation in Patients with Visceral Leishmaniasis

Visceral leishmaniasis (VL) affects organs rich in lymphocytes, being characterized by intense Leishmania-induced T-cell depletion and reduction in other hematopoietic cells. In other infectious and non-infectious diseases in which the immune system is affected, such as HIV-AIDS and inflammatory bowel disease, damage to gut-associated lymphocyte tissues occurs, enabling luminal bacteria to enter into the circulation. Lipopolisaccharide (LPS) is a bacterial product that stimulates macrophages, leading to the production of pro-inflammatory cytokines and other soluble factors such as MIF, which in turn activate lymphocytes. Continuous and exaggerated stimulation causes exhaustion of the T-cell compartment, contributing to immunosuppression

Association between Plasma Antibody Response and Protection in Rainbow Trout Oncorhynchus mykiss Immersion Vaccinated against Yersinia ruckeri

A key hallmark of the vertebrate adaptive immune system is the generation of antigen-specific antibodies from B cells. Fish are the most primitive gnathostomes (jawed vertebrates) possessing an adaptive immune system. Vaccination of rainbow trout against enteric redmouth disease (ERM) by immersion in Yersinia ruckeri bacterin confers a high degree of protection to the fish. The immune mechanisms responsible for protection may comprise both cellular and humoral elements but the role of specific immunoglobulins in this system has been questioned and not previously described. The present study demonstrates significant increase in plasma antibody titers following immersion vaccination and significantly reduced mortality during Y. ruckeri challenge