1. Center for Information Science and Technology, Temple University, Philadelphia, Pennsylvania 19122, Laboratory of Statistical Genetics, The Rockefeller University, New York, New York 10021, Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University, School of Medicine, Indianapolis, Indiana 46202, and Institute for Biological Instrumentation, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia