1. Zongwu Cai is Professor, Department of Mathematics and Statistics, University of North Carolina, Charlotte, NC 28223 and “Minjiang Scholar” Chair Professor, The Wang Yanan Institute for Studies in Economics, Xiamen University, China. Xiaoping Xu is Professor, Department of Statistics, College of Economics and Management, China University of Geosciences, Wuhan, China . Cai’s research was supported in part by National Science Foundation grant DMS-0404954 and funds provided by the University of North...