Evaluation of the optical conductivity tensor in terms of contour integrations

For the case of finite life-time broadening the standard Kubo-formula for the optical conductivity tensor is rederived in terms of Green's functions by using contour integrations, whereby finite temperatures are accounted for by using the Fermi-Dirac distribution function. For zero life-time broadening, the present formalism is related to expressions well-known in the literature. Numerical aspects of how to calculate the corresponding contour integrals are also outlined.Comment: 8 pages, Latex + 2 figure (Encapsulated Postscript

Core reconstruction in pseudopotential calculations

A new method is presented for obtaining all-electron results from a pseudopotential calculation. This is achieved by carrying out a localised calculation in the region of an atomic nucleus using the embedding potential method of Inglesfield [J.Phys. C {\bf 14}, 3795 (1981)]. In this method the core region is \emph{reconstructed}, and none of the simplifying approximations (such as spherical symmetry of the charge density/potential or frozen core electrons) that previous solutions to this problem have required are made. The embedding method requires an accurate real space Green function, and an analysis of the errors introduced in constructing this from a set of numerical eigenstates is given. Results are presented for an all-electron reconstruction of bulk aluminium, for both the charge density and the density of states.Comment: 14 pages, 5 figure

Large pinning forces and matching effects in YBa₂Cu₃O7-δ thin films with Ba₂Y(Nb/Ta)O₆ nano-precipitates

The addition of mixed double perovskite Ba2Y(Nb/Ta)O6 (BYNTO) to YBa2Cu3O7−δ (YBCO) thin films leads to a large improvement of the in-field current carrying capability. For low deposition rates, BYNTO grows as well-oriented, densely distributed nanocolumns. We achieved a pinning force density of 25 GN/m3 at 77 K at a matching field of 2.3 T, which is among the highest values reported for YBCO. The anisotropy of the critical current density shows a complex behavior whereby additional maxima are developed at field dependent angles. This is caused by a matching effect of the magnetic fields c-axis component. The exponent N of the current-voltage characteristics (inversely proportional to the creep rate S) allows the depinning mechanism to be determined. It changes from a double-kink excitation below the matching field to pinning-potential-determined creep above it

Ground-based Simulation of Upset Recovery in DESDEMONA: Aspects of Motion Cueing and Motion Perception

Unsuccessful recovery from unusual flight attitudes, or airplane upset, is considered an important factor in civil aviation accidents. It is generally recognized that there is a clear need for enhanced training of recovery procedures from unusual flight attitudes, i.e. situations where an aircraft unintentionally exceeds the parameters of the normal flight envelope. Exercising these conditions in the real world is unsafe, expensive and, if performed in smaller aircraft, not representative of the situation in commercial aircraft. Ground-based simulation of these extreme conditions is an interesting alternative for pilot instruction. However, at present, hexapod-based flight simulators used for pilot training are not certified for this purpose. Desdemona, a novel simulation facility, offers an extended motion envelope with enhanced motion capabilities which may prove adequate to simulate upset recovery events. The six degrees-of-freedom motion system features a gimbaled gondola which allows for unlimited rotation about three axes. In addition, the gondola can move up and down along a 2m long heave axis, and horizontally along an 8m long linear track. This track can be rotated on a planetary axis so as to produce a sustained linear acceleration up to 3G. The cockpit contains a projection system for out-the-window imagery, and can be reconfigured into different cockpit layouts. Desdemona has become operational in January 2008. This paper discusses the preliminary concepts for the simulation of upset recovery conditions based on the unique Desdemona motion features. This paper also introduces the motion envelope of upset conditions in support of pilot training

Planning a Wedding: Consumption behaviour of Bridal Magazines and Website Usage

This paper discusses the usage behaviour of brides-to-be in terms of bridal magazines and websites. Four hundred and forty six brides-to-be were questioned on their usage and attitudes toward print (magazines) and online (websites) when gathering their wedding planning information. Results indicated that respondents in this liminal state of moving from single to married status were clearly focused on investigating wedding products and services and extensively use both forms of media. Differences were evident in respondents’ usage of each medium dependent on wedding budgets, the particular wedding planning stages and the perceived comprehensiveness/ease of use of each medium. As a result it is extremely important for bridal magazines to have a website counterpart or extension, to increase their level of brand loyalty. These findings extend contemporary research into magazine consumption and introduce the uniqueness of the bridal media market. Implications for the bridal magazine industry are discussed

Circadian gene x environment perturbations influence alcohol drinking in Cryptochrome-deficient mice

Alcohol use disorder (AUD) is a widespread addiction disorder with severe consequences for health. AUD patients often suffer from sleep disturbances and irregular daily patterns. Conversely, disruptions of circadian rhythms are considered a risk factor for AUD and alcohol relapses. In this study, we investigated the extent to which circadian genetic and environmental disruptions and their interaction alter alcohol drinking behaviour in mice. As a model of genetic circadian disruption, we used Cryptochrome1/2-deficient (Cry1/2(-/-)) mice with strongly suppressed circadian rhythms and found that they exhibit significantly reduced preference for alcohol but increased incentive motivation to obtain it. Similarly, we found that low circadian SCN amplitude correlates with reduced alcohol preference in WT mice. Moreover, we show that the low alcohol preference of Cry1/2(-/-) mice concurs with high corticosterone and low levels of the orexin precursor prepro-orexin and that WT and Cry1/2(-/-) mice respond differently to alcohol withdrawal. As a model of environmentally induced disruption of circadian rhythms, we exposed mice to a "shift work" light/dark regimen, which also leads to a reduction in their alcohol preference. Interestingly, this effect is even more pronounced when genetic and environmental circadian perturbations interact in Cry1/2(-/-) mice under "shift work" conditions. In conclusion, our study demonstrates that in mice, disturbances in circadian rhythms have pronounced effects on alcohol consumption as well as on physiological factors and other behaviours associated with AUD and that the interaction between circadian genetic and environmental disturbances further alters alcohol consumption behaviour