A proposal to detect vortices above the superconducting transition temperature

We propose a simple experiment to determine whether vortices persist above the superconducting transition temperature Tc in the pseudogap phase of high temperature cuprate superconductors. This involves using a magnetic dot to stabilize a vortex in a thin cuprate film beneath the dot. We calculate the magnetic field profile as a function of distance from the dot if a vortex is present, and discuss possible measurements that could be done to detect this. Finally, we comment on the temperature range where a stable vortex should be observable.Comment: 3 pages, 2 figure

Periodic discrete conformal maps

A discrete conformal map (DCM) maps the square lattice to the Riemann sphere such that the image of every irreducible square has the same cross-ratio. This paper shows that every periodic DCM can be determined from spectral data (a hyperelliptic compact Riemann surface, called the spectral curve, equipped with some marked points). Each point of the map corresponds to a line bundle over the spectral curve so that the map corresponds to a discrete subgroup of the Jacobi variety. We derive an explicit formula for the generic maps using Riemann theta functions, describe the typical singularities and give a geometric interpretation of DCM's as a discrete version of the Schwarzian KdV equation. As such, the DCM equation is a discrete soliton equation and we describe the dressing action of a loop group on the set of DCM's. We also show that this action corresponds to a lattice of isospectral Darboux transforms for the finite gap solutions of the KdV equation.Comment: 41 pages, 10 figures, LaTeX2

Double dispersion of the magnetic resonant mode in cuprates

The magnetic excitation spectra in the vicinity of the resonant peak, as observed by inelastic neutron scattering in cuprates, are studied within the memory-function approach. It is shown that at intermediate doping the superconducting gap induces a double dispersion of the peak, with an anisotropy rotated between the downward and upward branch. Similar behavior, but with a spin-wave dispersion at higher energies, is obtained for the low-doping case assuming a large pairing pseudogap.Comment: 4 LaTeX pages, 4 figure

Unquenched large orbital magnetic moment in NiO

Magnetic properties of NiO are investigated by incorporating the spin-orbit interaction in the LSDA+U scheme. It is found that the large part of orbital moment remains unquenched in NiO. The orbital moment contributes about mu_L = 0.29 mu_B to the total magnetic moment of M = 1.93 mu_B, as leads to the orbital-to-spin angular momentum ratio of L/S = 0.36. The theoretical values are in good agreement with recent magnetic X-ray scattering measurements.Comment: 4 pages, 2 figure

RAM: A Relativistic Adaptive Mesh Refinement Hydrodynamics Code

We have developed a new computer code, RAM, to solve the conservative equations of special relativistic hydrodynamics (SRHD) using adaptive mesh refinement (AMR) on parallel computers. We have implemented a characteristic-wise, finite difference, weighted essentially non-oscillatory (WENO) scheme using the full characteristic decomposition of the SRHD equations to achieve fifth-order accuracy in space. For time integration we use the method of lines with a third-order total variation diminishing (TVD) Runge-Kutta scheme. We have also implemented fourth and fifth order Runge-Kutta time integration schemes for comparison. The implementation of AMR and parallelization is based on the FLASH code. RAM is modular and includes the capability to easily swap hydrodynamics solvers, reconstruction methods and physics modules. In addition to WENO we have implemented a finite volume module with the piecewise parabolic method (PPM) for reconstruction and the modified Marquina approximate Riemann solver to work with TVD Runge-Kutta time integration. We examine the difficulty of accurately simulating shear flows in numerical relativistic hydrodynamics codes. We show that under-resolved simulations of simple test problems with transverse velocity components produce incorrect results and demonstrate the ability of RAM to correctly solve these problems. RAM has been tested in one, two and three dimensions and in Cartesian, cylindrical and spherical coordinates. We have demonstrated fifth-order accuracy for WENO in one and two dimensions and performed detailed comparison with other schemes for which we show significantly lower convergence rates. Extensive testing is presented demonstrating the ability of RAM to address challenging open questions in relativistic astrophysics.Comment: ApJS in press, 21 pages including 18 figures (6 color figures

Assessing Psychosocial Work Environments of Coaches in Spain and Their Relationships With Mental Health, Behavioral Stress Symptoms, and Burnout

The purpose of this study was to assess the psychosocial work environments (PWE) among a sample of coaches in comparison to the reference values of the Spanish general workforce, as well as to explore the relationship between PWE and mental health, behavioral stress symptoms, and burnout. A representative sample (n=1481) of Spanish coaches (18.1% women, Mage=32.98, SD=11.60) completed a battery of questionnaires. Results showed that, in comparison to the general workforce, coaches showed statistically significant differences in most of the PWE areas assessed. The emotional demands experienced by coaches are a risk for health, while trust regarding management and recognition are positive features in their PWE. Coaches’ emotional demands were associated with low mental health scores and higher levels of behavioral stress symptoms and burnout, whereas social community at work and role clarity were protective factors for health. Practical implications to provide more favorable work environments for coaches are discussed

Overview of the University of Pennsylvania CORE System Standard Graphics Package Implementation

The CORE System is a proposed standard for a device-independent graphics system. The concept of a device-independent system was first developed in 1977 by the Graphics Standards Planning Committee (GSPC) of ACM Siggraph and later refined in 1979 [1,2]. The CORE System design has received favorable reviews and has been implemented by various vendors at several universities, and other computing facilities (e.g. [3,7]). The main objectives of the CORE System are to provide uniformity, compatibility, and flexibility in graphics software. Three advantages that the CORE system provides over non-standard graphics systems are device independence, program portability, and functional completeness. A large number of different graphics hardware devices currently exist with a wide range of available functions. The CORE System provides device independence by shielding the applications programmer from specific hardware characteristics. The shielding is at the functional level: the device-independent (DI) system uses internal routines to convert the application programmer\u27s functional commands to specific commands for the selected hardware device driver (DD). The progammer describes a graphical world to the CORE System in device-independent normalized device coordinates. The programmer also specifies the viewport on the logical view surface (output device) where a picture segment is to be placed. As the CORE System becomes the accepted standard graphics package, program portability will become more feasible. Program portability means the ability to transport application programs between two sites without requiring structural modifications. The CORE System was designed for functional completeness so that any graphics function a programmer desires is either included within the system or can be easily built on top of CORE System routines

Dephasing by extremely dilute magnetic impurities revealed by Aharonov-Bohm oscillations

We have probed the magnetic field dependence of the electron phase coherence time $\tau_\phi$ by measuring the Aharonov-Bohm conductance oscillations of mesoscopic Cu rings. Whereas $\tau_\phi$ determined from the low-field magnetoresistance saturates below 1 K, the amplitude of Aharonov-Bohm $h/e$ oscillations increases strongly on a magnetic field scale proportional to the temperature. This provides strong evidence that a likely explanation for the frequently observed saturation of $\tau_\phi$ at low temperature in weakly disordered metallic thin films is the presence of extremely dilute magnetic impurities.Comment: Accepted for publication in Physical Review Letter

Game On? Smoking Cessation Through the Gamification of mHealth: A Longitudinal Qualitative Study

BACKGROUND: Finding ways to increase and sustain engagement with mHealth interventions has become a challenge during application development. While gamification shows promise and has proven effective in many fields, critical questions remain concerning how to use gamification to modify health behavior. OBJECTIVE: The objective of this study is to investigate how the gamification of mHealth interventions leads to a change in health behavior, specifically with respect to smoking cessation. METHODS: We conducted a qualitative longitudinal study using a sample of 16 smokers divided into 2 cohorts (one used a gamified intervention and the other used a nongamified intervention). Each participant underwent 4 semistructured interviews over a period of 5 weeks. Semistructured interviews were also conducted with 4 experts in gamification, mHealth, and smoking cessation. Interviews were transcribed verbatim and thematic analysis undertaken. RESULTS: Results indicated perceived behavioral control and intrinsic motivation acted as positive drivers to game engagement and consequently positive health behavior. Importantly, external social influences exerted a negative effect. We identified 3 critical factors, whose presence was necessary for game engagement: purpose (explicit purpose known by the user), user alignment (congruency of game and user objectives), and functional utility (a well-designed game). We summarize these findings in a framework to guide the future development of gamified mHealth interventions. CONCLUSIONS: Gamification holds the potential for a low-cost, highly effective mHealth solution that may replace or supplement the behavioral support component found in current smoking cessation programs. The framework reported here has been built on evidence specific to smoking cessation, however it can be adapted to health interventions in other disease categories. Future research is required to evaluate the generalizability and effectiveness of the framework, directly against current behavioral support therapy interventions in smoking cessation and beyond