Ising model with periodic pinning of mobile defects

A two-dimensional Ising model with short-range interactions and mobile defects describing the formation and thermal destruction of defect stripes is studied. In particular, the effect of a local pinning of the defects at the sites of straight equidistant lines is analysed using Monte Carlo simulations and the transfer matrix method. The pinning leads to a long-range ordered magnetic phase at low temperatures. The dependence of the phase transition temperature, at which the defect stripes are destabilized, on the pinning strength is determined. The transition seems to be of first order, with and without pinning.Comment: 7 pages, 7 figure

The High Voltage Feedthroughs for the ATLAS Liquid Argon Calorimeters

The purpose, design specifications, construction techniques, and testing methods are described for the high voltage feedthrough ports and filters of the ATLAS Liquid Argon calorimeters. These feedthroughs carry about 5000 high voltage wires from a room-temperature environment (300 K) through the cryostat walls to the calorimeters cells (89 K) while maintaining the electrical and cryogenic integrity of the system. The feedthrough wiring and filters operate at a maximum high voltage of 2.5 kV without danger of degradation by corona discharges or radiation at the Large Hadron Collider

Effect of Segmental Bronchoalveolar Lavage on Quantitative Computed Tomography of the Lung

Rationale and Objectives: With employment of both multidetector computed tomography (MDCT) and endobronchial procedures in multicenter studies, effects of timing of endobronchial procedures on quantitative imaging (Q-MDCT) metrics is a question of increasing importance.Materials and Methods: Six subjects were studied via MDCT at baseline, immediately following and at 4 hours and 24 hours post-bronchoalveolar lavage (SAL) (right middle lobe and lingula). Through quantitative image analysis, non-air, or "tissue" volume (TV) in each lung and lobe was recorded. Change in TV from baseline was used to infer retention and redistribution of lavage fluid.Results: Bronchoscopist reported unrecovered BAL volume correlated well with Q-MDCT for whole lung measures, but less well with individual lobes indicating redistribution. TV in all lobes except the right lower lobe differed significantly (P &lt;.05) from baseline immediately post lavage. At 24 hours, all lobes except the left lower lobe (small 1% mean difference at 24 hours) returned to baseline.Conclusions: These findings suggest fluid movement affecting Q-MDCT metrics between lobes and between lungs before eventual resolution, and preclude protocols involving the lavage of one lung and imaging of the other to avoid interactions. We demonstrate that Q-MDCT is sensitive to lavage fluid retention and redistribution, and endobronchial procedures should not precede Q-MDCT imaging by less than 24 hours.</p

Expansion of Vortex Cores by Strong Electronic Correlation in La2−x_{2-x}Srx_xCuO4_4 at Low Magnetic Induction

The vortex core radius \rv, defined as the peak position of the supercurrent around the vortex, has been determined by muon spin rotation measurements in the mixed state of \lscox for $x=0.13$, 0.15, and 0.19. At lower doping (x=0.13 and 0.15), \rv(T) increases with decreasing temperature T, which is opposite to the behavior predicted by the conventional theory. Moreover, \rv(T\to0) is significantly larger than the Ginsburg-Landau coherence length determined by the upper critical field, and shows a clear tendency to decrease with increasing the doping x. These features can be qualitatively reproduced in a microscopic model involving antiferromagnetic electronic correlations.Comment: 6 pages, 4 figures, to be published in Phys. Rev.

Indirect search for dark matter: prospects for GLAST

Possible indirect detection of neutralino, through its gamma-ray annihilation product, by the forthcoming GLAST satellite from our galactic halo, M31, M87 and the dwarf galaxies Draco and Sagittarius is studied. Gamma-ray fluxes are evaluated for the two representative energy thresholds, 0.1 GeV and 1.0 GeV, at which the spatial resolution of GLAST varies considerably. Apart from dwarfs which are described either by a modified Plummer profile or by a tidally-truncated King profiles, fluxes are compared for halos with central cusps and cores. It is demonstrated that substructures, irrespective of their profiles, enhance the gamma-ray emission only marginally. The expected gamma-ray intensity above 1 GeV at high galactic latitudes is consistent with the residual emission derived from EGRET data if the density profile has a central core and the neutralino mass is less than 50 GeV, whereas for a central cusp only a substantial enhancement would explain the observations. From M31, the flux can be detected above 0.1 GeV and 1.0 GeV by GLAST only if the neutralino mass is below 300 GeV and if the density profile has a central cusp, case in which a significant boost in the gamma-ray emission is produced by the central black hole. For Sagittarius, the flux above 0.1 GeV is detectable by GLAST provided the neutralino mass is below 50 GeV. From M87 and Draco the fluxes are always below the sensitivity limit of GLAST.Comment: 14 Pages, 7 Figures, 3 Tables, version to appear on Physical Review

The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect

A measurement of the tau mass and the first CPT test with tau leptons

We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV using tau pairs from Z0 decays. To test CPT invariance we compare the masses of the positively and negatively charged tau leptons. The relative mass difference is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.

Search for R-Parity Violating Decays of Scalar Fermions at LEP

A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.

A Measurement of the Product Branching Ratio f(b->Lambda_b).BR(Lambda_b->Lambda X) in Z0 Decays

The product branching ratio, f(b->Lambda_b).BR(Lambda_b->Lambda X), where Lambda_b denotes any weakly-decaying b-baryon, has been measured using the OPAL detector at LEP. Lambda_b are selected by the presence of energetic Lambda particles in bottom events tagged by the presence of displaced secondary vertices. A fit to the momenta of the Lambda particles separates signal from B meson and fragmentation backgrounds. The measured product branching ratio is f(b->Lambda_b).BR(Lambda_b->Lambda X) = (2.67+-0.38(stat)+0.67-0.60(sys))% Combined with a previous OPAL measurement, one obtains f(b->Lambda_b).BR(Lambda_b->Lambda X) = (3.50+-0.32(stat)+-0.35(sys))%.Comment: 16 pages, LaTeX, 3 eps figs included, submitted to the European Physical Journal

The ANTARES Optical Beacon System

ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.Comment: 21 pages, 18 figures, submitted to Nucl. Instr. and Meth. Phys. Res.