NSFCNational Natural Science Foundation of China (NSFC) [10901067, 10801058, 10901165]; Special Fund for Basic Scientific Research of Central Colleges [CCNU10A02015]; Hubei Key Laboratory of Mathematical Sciences; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities [101gpy25]; China Post-doctoral Science FoundationChina Postdoctoral Science Foundation [201003382]