New global stability estimates for the Gel'fand-Calderon inverse problem

We prove new global stability estimates for the Gel'fand-Calderon inverse problem in 3D. For sufficiently regular potentials this result of the present work is a principal improvement of the result of [G. Alessandrini, Stable determination of conductivity by boundary measurements, Appl. Anal. 27 (1988), 153-172]

New Variational Principles in Classical and Semiclassical Mechanics

We demonstrate that reciprocal Maupertuis' Principle is the classical limit of Schr\"{o}dinger's Variational Principle in Quantum Mechanics.Comment: To appear in the Michael Marinov Memorial Volume, "Multiple facets of quantization and supersymmetry", edited by M. Olshanetsky and A. Vainshtein (World Scientific). We corrected TEX style of the paper so that the names of both authors can be seen in PS file no