BPS states of D=4 N=1 supersymmetry

We find the combinations of momentum and domain-wall charges corresponding to BPS states preserving 1/4, 1/2 or 3/4 of D=4 N=1 supersymmetry, and we show how the supersymmetry algebra implies their stability. These states form the boundary of the convex cone associated with the Jordan algebra of $4\times 4$ real symmetric matrices, and we explore some implications of the associated geometry. For the Wess-Zumino model we derive the conditions for preservation of 1/4 supersymmetry when one of two parallel domain-walls is rotated and in addition show that this model does not admit any classical configurations with 3/4 supersymmetry. Our analysis also provides information about BPS states of N=1 D=4 anti-de Sitter supersymmetry.Comment: Latex, 27 pages. Various corrections and improvements including an expanded discussion on BPS states in ad

The coupling between pulsation and mass loss in massive stars

To what extent can pulsational instabilities resolve the mass-loss problem of massive stars? How important is pulsation in structuring and modulating the winds of these stars? What role does pulsation play in redistributing angular momentum in massive stars? Although I cannot offer answers to these questions, I hope at the very least to explain how they come to be asked.Comment: 12 pages, 1 figure, to appear in proceedings of "Unsolved Problems in Stellar Physics" conference (Cambridge, UK, July 2007

‘Put that in your fucking research’: reflexivity, ethnography and disability sport coaching

Reflexivity is continually called for as a marker of quality ethnographic research. In this paper we put reflexivity to ‘work’, providing a critical commentary on data generated through ethnographic fieldwork in high-performance disability sport. Drawing on Bourdieu’s reflexive sociology, we situate the ethnographer in the field of disability sport, turning a reflexive lens onto the practices that are associated with occupying the role of coach and researcher simultaneously. We illustrate the centrality of researcher subjectivity – through the reflexive device of ‘crossing fields’ – as a productive resource for examining the social and intellectual unconscious embedded in the process of doing ethnographic research. In so doing, we provide a unique example of how reflexive practice can offer a rigorous, power-conscious reading of an ethnography of high-performance coaching in disability sport

Technology-enhanced learning in coaching: a review of literature

The purpose of this review was to address the central theme of technology-enhanced learning (TEL) in coaching. “Technology-enhanced learning” (TEL), has become a widely-accepted term for describing the interface between digital technology and teaching. The aim was to consider the evidence of TEL in coach education, and where appropriate the wider educational field. The review sought to contribute to an evidence base of suggestions that can be promoted and developed inside and outside of coach development structures and interventions for TEL. In addition, the review sought to outline future areas for research, and to stimulate debate about the implementation and effectiveness of technology-enhanced coach learning. The review utilised a critical methodology, using principles of systematic review to gather evidence pertaining to TEL in coaching. From this number, and considering the inclusion criteria, 64 articles were included and reviewed in detail. The review revealed how despite the use of technology in coaching, teaching and learning the evidence of their efficacy is weak, and the use of TEL in coaching requires further longitudinal research that considers learner, pedagogy and pedagogic design in context, in order to understand its potential impact on optimising coach development pedagogies, and therefore, contributing to a discourse of effective coach learning