This award from the U.S.-Argentina Cooperative Science Program supports research in mathematics to be conducted by Dr. Jim Douglas, Jr. of Purdue University and Dr. Juan E. Santos of the University of La Plata, Argentina. The goal of the project is to continue development of a parallelizable technique for approximating waves in composite media with one outcome being mathematically-justified parallel algorithms. The project continues an active collaboration between two well-regarded researchers. The project focuses on the development of an efficient, parallelizable technique for approximating waves in a composite medium consisting in part of a fluid region and in part of a fluid-saturated elastic region; a problem that arises in the simulation of acoustic well- logging. The numerical methods to be studied relate to space-frequency descriptions of the waves in place of the more common space-time descriptions. The research is to be divided almost evenly between the Purdue and La Plata groups, with a major part of the experimental calculations carried out by the former. ***