On the photoisomerization of the benzisothiazole portion of ziprasidone

Photostability challenge of ziprasidone in solution shows that the benzisothiazole moiety undergoes isomerization to the corresponding benzthiazole. A model compound, 3-piperazinyl-1,2-benzisothiazole, also undergoes this photoisomerization. Identification of the products has been confirmed by synthesis of the proposed molecules.     

Critical exponents for groups of isometries

Let Γ be a convex co-compact group of isometries of a CAT(−1) space X and let Γ₀ be a normal subgroup of Γ. We show that, provided Γ is a free group, a sufficient condition for Γ and Γ₀ to have the same critical exponent is that Γ / Γ₀ is amenable.      

Improving the efficiency of certain optically pumped lasers

It is shown that for certain optically excited symmetric top molecules which lase in the far-infrared that it is possible to increase their lasing efficiency through resonant pumping of the higher k quantum number transitions which have increased statistical weights due to increased molecular symmetry.     

A rapid method for calculating derivatives of solvent accessible surface areas of molecules

A novel method to calculate the derivatives of solvent accessible surface areas is presented. Unlike earlier analytic methods, which require the molecular topology and the use of global Gauss-Bonnet theorem, this method requires only the fractional accessibilities of surface arcs. We developed an efficient numerical algorithm to calculate the surface arcs by creating a uniform set of points on the circles of intersection between surface atoms. A hierarchical point density doubling scheme led to a logarithmic dependence of Central Processing Unit (CPU) time on the number of points used. This algorithm calculated area derivatives for a 1000-atom protein in 1.5 s on an SGI INDIGO² which were within 2% of the analytic area derivatives calculated with the program ANAREA. This algorithm scales linearly with the number of atoms for large molecules and is easily parallelizable. © 1995 by John Wiley & Sons, Inc.     

AnS matrix theory for classical nonlinear physics

The basic concepts appropriate for anS matrix theory for classical nonlinear physics are formulated here. These concepts are illustrated by a discussion of shock wave diffraction patterns. Other information concerning solutions of non-linear conservation laws is surveyed, so that a coherent picture of this theory can be seen. Within thisS matrix framework, a number of open problems as well as a few solved ones will be discussed.Dedicated to John A. Wheeler on the occasion of his 75th birthday.Supported in part by the National Science Foundation, grant DMS-831229.Supported in part by the Aplied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under contract DE-AC02-76ER03077.Supported in part by the Army Research Office, grant DAAG29-83-K-0007.Work supported by the U.S. Department of Energy.