1. Laboratory for Information and Decision Systems, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Mass., U.S.A.
2. Flint Hills Scientific, L.L.C., Lawrence, Kansas, U.S.A.
3. Comprehensive Epilepsy Center, Kansas City, Kansas, U.S.A.; Flint Hills Scientific, L.L.C., Lawrence, Kansas, U.S.A.
4. Department of Mathematics, University of Kansas, Lawrence, Ks., U.S.A.
5. University of Kansas Medical Center, Kansas City, Kansas, U.S.A.