Switching of the vortex polarity in a magnetic nanodisk by a DC current

We study the dynamics of a vortex state nanodisk due to a dc spin current, perpendicular to the disk plane. The irreversible switching of the vortex polarity takes place above some threshold current. The detailed description of these processes is obtained by spin-lattice simulations.Comment: REVTeX, 4 pages, 3 figure

Temperature evolution and bifurcations of metastable states in mean-field spin glasses, with connections with structural glasses

The correlations of the free-energy landscape of mean-field spin glasses at different temperatures are investigated, concentrating on models with a first order freezing transition. Using a ``potential function'' we follow the metastable states of the model in temperature, and discuss the possibility of level crossing (which we do not find) and multifurcation (which we find). The dynamics at a given temperature starting from an equilibrium configuration at a different temperature is also discussed. In presence of multifurcation, we find that the equilibrium is never achieved, leading to aging behaviour at slower energy levels than usual aging. The relevance of the observed mechanisms for real structural glasses is discussed, and some numerical simulations of a soft sphere model of glass are presented.Comment: 16 pages, LaTeX, 10 figures (12 postscript files

The roles of the subunits in the function of the calcium channel

Dihydropyridine-sensitive voltage-dependent L-type calcium channels are critical to excitation-secretion and excitation-contraction coupling. The channel molecule is a complex of the main, pore-forming subunit alpha 1 and four additional subunits: alpha 2, delta, beta, and gamma (alpha 2 and delta are encoded by a single messenger RNA). The alpha 1 subunit messenger RNA alone directs expression of functional calcium channels in Xenopus oocytes, and coexpression of the alpha 2/delta and beta subunits enhances the amplitude of the current. The alpha 2, delta, and gamma subunits also have pronounced effects on its macroscopic characteristics, such as kinetics, voltage dependence of activation and inactivation, and enhancement by a dihydropyridine agonist. In some cases, specific modulatory functions can be assigned to individual subunits, whereas in other cases the different subunits appear to act in concert to modulate the properties of the channel

Effective "Penetration Depth" in the Vortex State of a d-wave Superconductor

The temperature and field dependence of the effective magnetic penetration depth in the vortex state of a d-wave superconductor, as measured by muon spin rotation experiments, is calculated using a nonlocal London model. We show that at temperatures below T^* \propto \sqrt{B}, the linear T-dependence of the effective penetration depth crosses over to a T^3-dependence. This could provide an explanation for the low temperature flattening of the effective penetration depth curves observed in a recent muon spin rotation experiment.Comment: 4 pages, RevTex, 3 Postscript figure

The theory of planned behaviour, self-identity, and moral disengagement: what predicts sustainability at work?

Objectives: On the occasion of the Green Impact sustainability initiative at our university, we sought to identify predictors of sustainability-related behaviours (recycling, energy saving and sustainable transport choices) among staff. Design: A quantitative on-line survey was conducted among university staff. In line with the theory of planned behaviour (TPB), we measured intentions (to recycle, to save energy, and to choose sustainable transport), attitudes, subjective norm, and perceived control. Self-identity was added as a popular extension to the TPB. Additionally, we took one of the first measurements of moral disengagement in a sustainability-related study. Methods: All staff participating in the initiative were contacted, 130 responses were received. Correlational methods were used to analyse the survey data. Results: The TPB was broadly supported; however, perceived control was not significant in predicting recycling intentions, subjective norm did not contribute to the prediction of energy saving intentions, and attitude did not predict transport intentions. Self-identity, conversely, made a substantial additional contribution for all target behaviours. The moral disengagement measures were all correlated with sustainability intentions, but there were multicollinearity issues with the TPB variables and between sub-scales. Conclusions: The TPB is useful in predicting workplace sustainability intentions, but different predictors apply to different behaviours. Moral disengagement is another useful explanatory concept, but difficult to incorporate in the TPB. The consistently significant contribution of self-identity suggests that sustainability at work can be promoted by making staff feel like sustainability champions

Sustainability in the workplace and the theory of planned behaviour: Norms and identity predict environmentally friendly intentions

Social psychology offers an insightful perspective on the psychological processes underlying sustainability-related intentions and actions, at universities and elsewhere. Ajzen’s theory of planned behaviour (TPB) is a well-supported model, positing that attitudes alone will rarely predict intentions and behaviour accurately. Rather, individuals are sensitive to social norms (the perceived requirements of a setting and/or a group to which the actor belongs) and perceived control (the sense that the actor is capable of the behaviour and the environment offers the opportunity). Recently, it has been suggested to include self-identity (the notion that the behaviour is part of who you are). This paper summarises previous research linking the TPB to sustainability, and then reports a quantitative survey of 130 staff members at Canterbury Christ Church University. An online questionnaire measured attitudes, social norms, perceived control, self-identity, and intentions relating to office waste recycling, energy saving, and transport choice. Overall, only self-identity and norms reliably predicted intentions to act in environmentally sustainable ways. Follow-up analyses suggest that different predictors were significant for different intentions, but self-identity always improved prediction over and above the original TPB variables. In conclusion, universities can best cultivate sustainability intentions by promoting favourable norms and self-identities

Two different quasiparticle scattering rates in vortex line liquid phase of layered d-wave superconductors

We carry out a quantum mechanical analysis of the behavior of nodal quasiparticles in the vortex line liquid phase of planar d-wave superconductors. Applying a novel path integral technique we calculate a number of experimentally relevant observables and demonstrate that in the low-field regime the quasiparticle scattering rates deduced from photoemission and thermal transport data can be markedly different from that extracted from tunneling, specific heat, superfluid stiffness or spin-lattice relaxation time.Comment: Latex, 4 pages, no figure