[Zhang, Wen-Xing] Cent China Normal Univ, Inst Econ & Business Adm, Wuhan, Hubei, Peoples R China.^[Dong, Ping] Colorado State Univ, Ft Collins, CO 80523 USA.^[Dong, Li-Min] Cent China Normal Univ, Inst Econ & Business Adm, Wuhan, Hubei, Peoples R China.