1,230 research outputs found
Information from quantum blackhole physics
The study of BTZ blackhole physics and the cosmological horizon of 3D de
Sitter spaces are carried out in unified way using the connections to the Chern
Simons theory on three manifolds with boundary. The relations to CFT on the
boundary is exploited to construct exact partition functions and obtain
logarithmic corrections to Bekenstein formula in the asymptotic regime.
Comments are made on the dS/CFT correspondence frising from these studies.Comment: 11 pages; 1 figure(eps file);Talk presented at the conference
Space-time and Fundamental Interactions: Quantum Aspects'' in honour of A.P.
Balachandran's 65th birthday, Vietri sul Mare, Salerno, Italy 26th-31st May,
200
Dynamics of circular arrangements of vorticity in two dimensions
The merger of two like-signed vortices is a well-studied problem, but in a
turbulent flow, we may often have more than two like-signed vortices
interacting. We study the merger of three or more identical co-rotating
vortices initially arranged on the vertices of a regular polygon. At low to
moderate Reynolds numbers, we find an additional stage in the merger process,
absent in the merger of two vortices, where an annular vortical structure is
formed and is long-lived. Vortex merger is slowed down significantly due to
this. Such annular vortices are known at far higher Reynolds numbers in studies
of tropical cyclones, which have been noticed to a break down into individual
vortices. In the pre-annular stage, vortical structures in a viscous flow are
found here to tilt and realign in a manner similar to the inviscid case, but
the pronounced filaments visible in the latter are practically absent in the
former. Interestingly at higher Reynolds numbers, the merger of an odd number
of vortices is found to proceed very differently from that of an even number.
The former process is rapid and chaotic whereas the latter proceeds more slowly
via pairing events. The annular vortex takes the form of a generalised
Lamb-Oseen vortex (GLO), and diffuses inwards until it forms a standard
Lamb-Oseen vortex. For lower Reynolds number, the numerical (fully nonlinear)
evolution of the GLO vortex follows exactly the analytical evolution until
merger. At higher Reynolds numbers, the annulus goes through instabilities
whose nonlinear stages show a pronounced difference between even and odd mode
disturbances. It is hoped that the present findings, that multiple vortex
merger is qualitatively different from the merger of two vortices, will
motivate studies on how multiple vortex interactions affect the inverse cascade
in two-dimensional turbulence.Comment: Abstract truncated. Paper to appear in Physical Review
Genus Zero Correlation Functions in c<1 String Theory
We compute N-point correlation functions of pure vertex operator states(DK
states) for minimal models coupled to gravity. We obtain agreement with the
matrix model results on analytically continuing in the numbers of cosmological
constant operators and matter screening operators. We illustrate this for the
cases of the and models.Comment: 11 pages, LaTeX, IMSc--92/35. (revised) minor changes plus one
reference adde
BTZ Black Hole Entropy from Ponzano-Regge Gravity
The entropy of the BTZ black hole is computed in the Ponzano-Regge
formulation of three-dimensional lattice gravity. It is seen that the correct
semi-classical behaviour of entropy is reproduced by states that correspond to
all possible triangulations of the Euclidean black hole.Comment: 11 pages LaTeX, 3 eps figures, some minor clarifications added,
result unchange
Artemisinin-based combination with curcumin adds a new dimension to malaria therapy
Malaria afflicts 300 million people worldwide, with over a million deaths every year. With no immediate prospect of a vaccine against the disease, drugs are the only choice to treat it. Unfortunately, the parasite has become resistant to most antimalarials, restricting the option to use artemisinins (ARTs) for effective cure. With the use of ARTs as the front-line antimalarials, reports are already available on the possible resistance development to these drugs as well. Therefore, it has become necessary to use ART-based combination therapies to delay emergence of resistance. It is also necessary to discover new pharmacophores to eventually replace ART. Studies in our laboratory have shown that curcumin not only synergizes with ART as an antimalarial to kill the parasite, but is also uniquely able to prime the immune system to protect against parasite recrudescence in the animal model. The results indicate a potential for the use of ART- curcumin combination against recrudescence/relapse in falciparum and vivax malaria. In addition, studies have also suggested the use of curcumin as an adjunct therapy against cerebral malaria. In this review we have attempted to highlight these aspects as well as the studies directed to discover new pharmacophores as potential replacements for ART
Semirigid Geometry
We provide an intrinsic description of -super \RS s and -\SR\
surfaces. Semirigid surfaces occur naturally in the description of topological
gravity as well as topological supergravity. We show that such surfaces are
obtained by an integrable reduction of the structure group of a complex
supermanifold. We also discuss the \s moduli spaces of -\SR\ surfaces and
their relation to the moduli spaces of -\s\ \RS s.Comment: 29p
Quasi-normal modes of AdS black holes : A superpotential approach
A novel method, based on superpotentials is proposed for obtaining the
quasi-normal modes of anti-de Sitter black holes. This is inspired by the case
of the three-dimensional BTZ black hole, where the quasi-normal modes can be
obtained exactly and are proportional to the surface gravity. Using this
approach, the quasi-normal modes of the five dimensional Schwarzschild
anti-deSitter black hole are computed numerically. The modes again seem to be
proportional to the surface gravity for very small and very large black holes.
They reflect the well-known instability of small black holes in anti-deSitter
space.Comment: LaTeX, 17 pages, 5 eps figures, 1 eepic figure, minor typos correcte
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