On tachyons, gauged linear sigma models, and flip transitions

We study systems of multiple localized closed string tachyons and the phenomena associated with their condensation, in C3/ZN nonsupersymmetric noncompact orbifold singularities using gauged linear sigma model constructions, following hep-th/0406039. Our study reveals close connections between the combinatorics of nonsupersymmetric flip transitions (between topologically distinct resolutions of the original singularity), the physics of tachyons of different degrees of relevance and the singularity structure of the corresponding residual endpoint geometries. This in turn can be used to study the stability of the phases of gauged linear sigma models and gain qualitative insight into the closed string tachyon potential.Comment: Latex, 38 pages, 7 eps figs. v2. minor modification

R. K. Narayanswami B.A.B.L. Engine Driver : Story-Telling and Memory in The Grandmother’s Tale, and Selected Stories

Much like the Nambi of this tale, R. K. Narayan has merited his reputation as a marvelous storyteller. Noted for his laser-beam focus on the closely-imagined Malgudi, he has come to be recognized as the Indian novelist, from whose pen many readers expected all the accumulated wisdom of the subcontinent\u27s abiding concern for transcendence. While such guru-ization amused Narayan, it also elicited his quietly sustained argument against procrustean templates by which the west insisted on reading him as typically Indian.

dS/CFT at uniform energy density and a de Sitter "bluewall"

We describe a class of spacetimes that are asymptotically de Sitter in the Poincare slicing. Assuming that a dS/CFT correspondence exists, we argue that these are gravity duals to a CFT on a circle leading to uniform energy-momentum density, and are equivalent to an analytic continuation of the Euclidean AdS black brane. These are solutions with a complex parameter which then gives a real energy-momentum density. We also discuss a related solution with the parameter continued to a real number, which we refer to as a de Sitter "bluewall". This spacetime has two asymptotic de Sitter universes and Cauchy horizons cloaking timelike singularities. We argue that the Cauchy horizons give rise to a blue-shift instability.Comment: Latex, 13pgs, 2 figs. v2: 14pgs, published version, some rephrasing of language in terms of Euclidean CFT on a circle, more elaborate discussion on blueshif

Depression, Anxiety and Stress Reduction in Medical Education: Humor as an Intervention

Background: In recent years there has been a growing appreciation of the issues of quality of life and stresses involved in medical training as this may affect their learning and academic performance. Objective of the study was to explore the effectiveness of humor when used as intervention in large group teaching over negative emotions amongst students. Method: The present Interventional, Randomized control trial study was carried out on medical students of 4th Semester of RMCH, Bareilly, which has total 90 students. Using simple random sampling lottery method the whole class was divided in two groups-A and B consisting of 45 students each. Group A as control group and Group B experimental group. In first and last lecture of both groups Dass-21 was used as measuring scale, for depression, anxiety and stress and results were compared to see the effect of humor on these three negative emotions. Result: Comparison of Severe and Extremely severe Stress: In Group A 40.54% in class -1 increased to 47.54% in class- 4, while in group B initial 13.15 % was reduced to 0 % (highly significant). Anxiety: In group A, after Class 1 -57.45% increased to 61.11% after class 4, while in group B, after class 1- 23.68% reduced to 2.27% only (highly significant). Depression: In group A, after Class 1 - 40.53% & 41.66 % after class 4 (not significant), while in group B, after class 1- 18.41% reduced to 0% (highly significant). Conclusion: In present study humor was found to be very effective intervention in relieving students on their negative emotions of depression, anxiety and stress to a larger extent. Further research would justify the use of humor as an effective teaching aid in medical education

A New Parameter In Accretion Disk Model

Taking optically thin accretion flows as an example, we investigate the dynamics and the emergent spectra of accretion flows with different outer boundary conditions (OBCs) and find that OBC plays an important role in accretion disk model. This is because the accretion equations describing the behavior of accretion flows are a set of {\em differential} equations, therefore, accretion is intrinsically an initial-value problem. We argue that optically thick accretion flow should also show OBC-dependent behavior. The result means that we should seriously consider the initial physical state of the accretion flow such as its angular momentum and its temperature. An application example to Sgr A$^*$ is presented.Comment: 6 pages, 4 figures, to appear in the Proceeding of "Pacific Rim Conference on Stellar Astrophysics", Aug. 1999, HongKong, Chin