In the rst part of this talk, I consider some exact string solutions in curved spacetimes. In curved spacetimes with a Killing vector (timelike or spacelike), the string equations of motion andâ€¦ (More)

We study a simple system that comprises all main features of critical gravitational collapse, originally discovered by Choptuik and discussed in many subsequent publications. These features includeâ€¦ (More)

It has been known for some time that the SL(2,R) WZWN model reduces to Liouville theory. Here we give a direct and physical derivation of this result based on the classical string equations of motionâ€¦ (More)

The exact general evolution of circular strings in 2 + 1 dimensional de Sitter spacetime is described closely and completely in terms of elliptic functions. The evolution depends on a constantâ€¦ (More)

Previous studies of cells from various species have indicated that exogenous calcium is necessary for gonadotropic stimulation of steroidogenesis. To determine whether this requirement for exogenousâ€¦ (More)

In this paper we make the connection between semi-classical string quanti-zation and exact conformal field theory quantization of strings in 2+1 Anti de Sitter spacetime. More precisely, consideringâ€¦ (More)

We consider classical and quantum strings in the conformally invariant background corresponding to the SL(2,R) WZWN model. This background is locally anti-de Sitter spacetime with non-vanishingâ€¦ (More)

We discuss the generalized Plateau problem in the 3+1 dimensional Schwarzschild background. This represents the physical situation, which could for instance have appeared in the early universe, whereâ€¦ (More)

We consider scattering and capture of circular cosmic strings by a Schwarzschild black hole. Although being apriory a very simple axially symmetric two-body problem, it shows all the features ofâ€¦ (More)