An action for the exact string black hole

A local action is constructed describing the exact string black hole discovered by Dijkgraaf, Verlinde and Verlinde in 1992. It turns out to be a special 2D Maxwell-dilaton gravity theory, linear in curvature and field strength. Two constants of motion exist: mass M>1, determined by the level k, and U(1)-charge Q>0, determined by the value of the dilaton at the origin. ADM mass, Hawking temperature T_H \propto \sqrt{1-1/M} and Bekenstein-Hawking entropy are derived and studied in detail. Winding/momentum mode duality implies the existence of a similar action, arising from a branch ambiguity, which describes the exact string naked singularity. In the strong coupling limit the solution dual to AdS_2 is found to be the 5D Schwarzschild black hole. Some applications to black hole thermodynamics and 2D string theory are discussed and generalizations - supersymmetric extension, coupling to matter and critical collapse, quantization - are pointed out.Comment: 41 pages, 2 eps figures, dedicated to Wolfgang Kummer on occasion of his Emeritierung; v2: added ref; v3: extended discussion in sections 3.2, 3.3 and at the end of 5.3 by adding 2 pages of clarifying text; updated refs; corrected typo

The Earth: Plasma Sources, Losses, and Transport Processes

This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed

What is rehabilitation potential? Development of a theoretical model through the accounts of healthcare professionals working in stroke rehabilitation services

Introduction: Multi-disciplinary team members predict each patient’s rehabilitation potential to maximise best use of resources. A lack of underpinning theory about rehabilitation potential makes it difficult to apply this concept in clinical practice. This study theorises about rehabilitation potential drawing on everyday decision-making by Health Care Professionals (HCPs) working in stroke rehabilitation services. Methods: A clinical scenario, checked for face validity, was used in two focus groups to explore meaning and practice around rehabilitation potential. Participants were 12 HCPs working across the stroke pathway. Groups were co-facilitated, audio-recorded and fully transcribed. Analysis paid attention to data grounded in first-hand experience, convergence within and across groups and constructed a conceptual overview of HCPs’ judgements about rehabilitation potential. Results: Rehabilitation potential is predicted by observations of “carry-over” and functional gain and managed differently across recovery trajectories. HCPs’ responses to rehabilitation potential judgements include prioritising workload, working around the system and balancing optimism and realism. Impacts for patients are streaming of rehabilitation intensity, rationing access to rehabilitation and a shifting emphasis between management and active rehabilitation. For staff, the emotional burden of judging rehabilitation potential is significant. Current service organisation restricts opportunities for feedback on the accuracy of previous judgements. Conclusion: Patients should have the opportunity to demonstrate rehabilitation potential by participation in therapy. As therapy resources are limited and responses to therapy may be context-dependent, early decisions about a lack of potential should not limit longer-term opportunities for rehabilitation. Services should develop strategies to enhance the quality of judgements through feedback to HCPs of longer-term patient outcomes. Implications for Rehabilitation Rehabilitation potential is judged at the level of individual patients (rather than population-based predictive models of rehabilitation outcome), draws on different sources of often experiential knowledge, and may be less than reliable. Decisions about rehabilitation potential may have far reaching consequences for individual patients, including the withdrawal of active rehabilitation in hospital or in the community and eventual care placement. A better understanding of what people mean by rehabilitation potential by all team members, and by patients and carers, may improve the quality of joint decision making and communication