1. Hyokyoung Grace Hong is Assistant Professor, Department of Statistics and CIS, The Baruch College of the City University of New York . Xuming He is Professor, Department of Statistics, University of Illinois at Urbana–Champaign, Champaign, IL 61820 . The research is partially supported by NSF grant DMS-0604229, NIH grant R01GM080503-01A1, U.S.A., National Natural Science Foundation of China grant 10828102, and a Changjiang Visiting Professorship at the Northeast Normal University, China. We thank the...