On Nonlocal Energy Transfer via Zonal Flow in the Dimits Shift

The two-dimensional Terry-Horton equation is shown to exhibit the Dimits shift when suitably modified to capture both the nonlinear enhancement of zonal/drift-wave interactions and the existence of residual Rosenbluth-Hinton states. This phenomenon persists through numerous simplifications of the equation, including a quasilinear approximation as well as a four-mode truncation. It is shown that the use of an appropriate adiabatic electron response, for which the electrons are not affected by the flux-averaged potential, results in an $\boldsymbol{E}\boldsymbol{\times}\boldsymbol{B}$ nonlinearity that can efficiently transfer energy nonlocally to length scales on the order of the sound radius. The size of the shift for the nonlinear system is heuristically calculated and found to be in excellent agreement with numerical solutions. The existence of the Dimits shift for this system is then understood as an ability of the unstable primary modes to efficiently couple to stable modes at smaller scales, and the shift ends when these stable modes eventually destabilize as the density gradient is increased. This nonlocal mechanism of energy transfer is argued to be generically important even for more physically complete systems.Comment: 28 pages, 7 figures, 4 movie

Ludic literacies at the intersections of cultures: an interview with James Paul Gee

Professor James Gee addresses issues of linguistics, literacies and cultures. Gee emphasises the importance of Discourses, and argues that the future of literacy studies lies in the interrogation of new media and the globalisation of culture

Optimization of perturbative similarity renormalization group for Hamiltonians with asymptotic freedom and bound states

A model Hamiltonian that exhibits asymptotic freedom and a bound state, is used to show on example that similarity renormalization group procedure can be tuned to improve convergence of perturbative derivation of effective Hamiltonians, through adjustment of the generator of the similarity transformation. The improvement is measured by comparing the eigenvalues of perturbatively calculated renormalized Hamiltonians that couple only a relatively small number of effective basis states, with the exact bound state energy in the model. The improved perturbative calculus leads to a few-percent accuracy in a systematic expansion.Comment: 6 pages of latex, 4 eps figure

Improved pulse shape discriminator for fast neutron-gamma ray detection system

Discriminator in nuclear particle detection system distinguishes nuclear particle type and energy among many different nuclear particles. Discriminator incorporates passive, linear circuit elements so that it will operate over a wide dynamic range

Applying Stage-Based Theory to engage female students in university sport

Purpose: University sport is recognized by many as a key area of university business and one of increasing importance, as seen by universities prioritizing sport within their university strategic plans as well as national funding bodies investing in university sport. Whilst sport is rising on the agenda, engaging all students in sport is a key challenge for universities. This paper examines the factors that enable and inhibit female students’ participation in university sport and active recreation using an interpretivist qualitative design. The paper also identified specific behaviour change techniques that could be used within interventions to increase participation rates. Method: Six focus groups were carried out. Data were analysed verbatim using a constant comparative process of analysis. Results: Findings revealed several emergent themes to help inform theory-based interventions to engage more female students in sport. Conclusion: University sport is an important behaviour for students to undertake. The paper identified a number of avenues for universities to pursue in order to achieve this aim

Ensuring an Impartial Jury in the Age of Social Media

The explosive growth of social networking has placed enormous pressure on one of the most fundamental of American institutions—the impartial jury. Through social networking services like Facebook and Twitter, jurors have committed significant and often high-profile acts of misconduct. Just recently, the Arkansas Supreme Court reversed a death sentence because a juror Tweeted about the case during deliberations. In light of the significant risks to a fair trial that arise when jurors communicate through social media during trial, judges must be vigilant in monitoring for potential outside influences and in deterring misconduct. In this Article, we present informal survey data from actual jurors on their use of social networking during trial. We discuss the rise of web-based social networks like Facebook and Twitter, and the concerns that arise when jurors communicate about a case through social media before returning a verdict. After surveying how courts have responded to jurors’ social media use, we describe the results of the informal survey. The results support a growing consensus in the legal profession that courts should frequently, as a matter of course, instruct jurors not to use social media to communicate about trial. Although others have stressed the importance of jury instructions in this area, we hope that the informal survey data will further the dialogue by providing an important perspective—that of actual jurors