SURFACE SINGULARITIES IN NEMATICS AND SOME NOTES ON CHOLESTERICS.

A topological analysis of surface and bulk configurations in cholesterics and nematics is given. Volovik's procedure for combining surface and bulk defects is reviewed and illustrated, and the problem of twist in cholesterics is discussed from the point of view of Cladis et al. These considerations are applied to cholesteric boojums. Also, the question of non-singular textures is studied and a soliton-like texture for a cholesteric is proposed and is predicted to be stable. Next, the problem of a nematic in a sphere is considered and the various solutions to this problem are given.