1. Jianwei Chen is Assistant Professor, Department of Mathematics and Statistics, San Diego State University, San Diego, CA 92182 . Hulin Wu is Professor, Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY 14642 . This work was completed while the first author was a postdoctoral research fellow at the University of Rochester. This work was supported by National Institute of Allergy and Infectious Diseases/National Institutes of Health grants RO1 AI 52765, RO1 AI...