Department of Software engineering, College of Mathematics and Informatics, Fujian Normal University, Fuzhou 350108, China.|Department of Computer Science & Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA.|Department of Pathology, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.|Department of Software engineering, College of Mathematics and Informatics, Fujian Normal University, Fuzhou 350108, China.