Department of Biology, Center for Genomics & Systems Biology, New York University, New York, NY 10003, Perinatology Research Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD and Detroit, MI 48201, USA, IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, Computer Science Department, Courant institute of Mathematical Sciences, New York University, New York, NY 10012 and Department of Computer Science, Wayne State University, Detroit, MI 48202, USA.