aResearch Center of Nonlinear Science, School of Mathematical and Physical Sciences, Wuhan Textile University, Wuhan, P R. China

bDepartment of Mathematics, Michigan State University, East Lansing, MI, United States

cKey Laboratory of Computational Mathematics, Guangdong Province, and School of Mathematics, Sun Yat-sen University, Guangzhou, P R. China

Departments of dElectrical and Computer Engineering and

eBiochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States

*Corresponding author. Address: Department of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States. Tel.: +01-517-353-4689. E-mail address: [email protected] (G. W. Wei).

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