Quantum Theory of Massless Particles in Stationary Axially Symmetric Spacetimes.

Quantum equations for massless particles of any spin are considered in stationary uncharged axially symmetric spacetimes. It is demonstrated that up to a normalization function, the angular wave function does not depend on the metric and practically is the same as in the Minkowskian case. The radial wave functions satisfy second order nonhomogeneous differential equations with three nonhomogeneous terms, which depend in a unique way on time and space curvatures.

Diamond shaped optical fiber delivery system.

Background: Optical fibers are generally used with a flat cut end. The adaptation of a coaxial exit of a refrigerated gas near the distal tip of the optical fiber cools the tissue where the laser beam is applied and reduces the injury of thermal effects on biological tissue.

Materials And Methods: We have changed the flat end geometry of the fiber's end to a pyramidal end shape (named: Diamond tip).