1. Earth Sciences Division, E. O. Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720
2. Department of Geological and Environmental Sciences, Stanford University, 138 Mitchell Building, Stanford, California 94305
3. Stanford Synchrotron Radiation Laboratory, SLAC, P.O. Box 4349, MS 69, Stanford, California 94309
4. Department of Geophysical Sciences and Consortium for Advanced Radiation Sources, The University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637
5. Lawrence Livermore National Laboratory, P.O. Box 808, L-395, Livermore, California 94550