1. Department of Computer Science, College of Engineering and Computer Science, California State University, Fullerton, CA, USA
2. Department of Computer Science, Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, USA
3. School of Computers, Guangdong University of Technology, Guangzhou, China
4. Department of Persuasive Information Systems, University of Oulu, Oulu, Finland