1. Institute of Bioinformatics, University of Georgia,Athens,GA,U.S.A.,30602-7229
2. University of Georgia,Dept. of Genetics,Athens,GA,U.S.A.,30602-7229
3. University of Georgia,Dept. of Statistics,Athens,GA,U.S.A.,30602-7229
4. School of Electrical & Computer Engineering, University of Georgia,MILAB,Athens,GA,U.S.A.,30602-7229