We present a microscopic index formula for the degeneracy of dyons in four-dimensional N = 4 string theory. This counting formula is manifestly symmetric under the duality group, and its asymptotic growth reproduces the macroscopic Bekenstein-Hawking en-tropy. We give a derivation of this result in terms of the type II ve-brane compactiied on K3, by assuming that its uctuations are described by...

A number of recent papers have demonstrated that camera "selfcalibration" can be accomplished purely from image measurements, without requiring special calibration objects or known camera motion. We describe a method, based on self-calibration, for obtaining (scaled) Euclidean structure from multiple uncalibrated perspective images using only point matches between views. The method is in two st...

Sunyaev-Zeldovich (SZ) effect from a cosmological distribution of clusters carry information on the underlying cosmology as well as the cluster gas physics. In order to study either cosmology or clusters one needs to break the degeneracies between the two. We present a toy model showing how complementary informations from SZ power spectrum and the SZ flux counts, both obtained from upcoming SZ ...

We characterize the conditions under which completing a Delaunay tessellation produces a connguration that is a nondegenerate Delaunay triangulation of an arbitrarily small perturbation of the original sites. One consequence of this result is a simple postpro-cessing step for resolving degeneracies in Delaunay triangulations that does not require symbolic perturbation of the data. We also give ...

The authors present a higher-order Godunov method for the solution of the twoand three-dimensional equations of ideal magnetohydrodynamics (MHD). This work is based both on a suitable operator-split approximation to the full multidimensional equations, and on a one-dimensional Riemann solver. TIlls Riemann solver is sufficiently robust to handle the nonstrictly hyperbolic nature of the MHD equa...

I review recent constraints on and claimed detections of a time-varying fine-structure constant α. Our results are consistent with no variation in α from the epoch of recombination to the present day, and restrict any such variation to be less than about 4%. The forthcoming MAP and Planck experiments will be able to break most of the currently existing degeneracies between α and other cosmologi...

We compute the boundary entropies for the allowed boundary conditions of the SU (2)-invariant principal chiral model at level k = 1. We used the reflection factors determined in ref.[27]. As a by-product we obtain some miscellaneous results such as the ground-state energy for mixed boundary conditions as well as the degeneracies of the Kondo model in the underscreened and exactly screened cases...

Stripping techniques combined with an adequate replication policy across the Grid offers the possibility to improve significatively data access and processing times, while eliminating the need for local data mirroring, so saving significatively on storage costs. First results on a local cluster following a simple strategy are presented.

The spectrum of eigenenergies of a quantum integrable system whose hamil-tonian depends on a single parameter shows degeneracies (crossings) when the parameter varies. We derive a semiclassical expression for the density of crossings in the plane energy-parameter, that is the number of crossings per unit of energy and unit of parameter, in terms of classical periodic orbits. We compare the resu...

We compute the boundary entropies for the allowed boundary conditions of the SU (2)-invariant principal chiral model at level k = 1. We used the reflection factors determined in a previous work. As a by-product we obtain some miscellaneous results such as the ground-state energy for mixed boundary conditions as well as the degeneracies of the Kondo model in the underscreened and exactly screene...