Angel A. Juan (ajuanp@gmail.com) is an associate professor of simulation and data analysis in the computer sciences department at the Open University of Catalonia (Spain). He is also a lecturer at the Technical University of Catalonia. He holds a PhD in industrial engineering (UNED), an MS in information technology (Open University of Catalonia), and an MS in applied computational mathematics (University of Valencia). His research interests include computer simulation, applied data analysis, and mathematical e-learning. He has published several papers in international journals, books, and proceedings regarding these fields. As a researcher, he has been involved in several international research projects. Thanasis Daradoumis (adaradoumis@uoc.edu) holds a PhD in computer science from the Polytechnic University of Catalonia (Spain), a master���s degree in computer science from the University of Illinois (USA), and a bachelor���s degree in mathematics from the University of Thessaloniki (Greece). He is an associate professor in the Department of Computer Sciences, Multimedia & Telecommunication at the Open University of Catalonia. His research focuses on e-learning and network technologies, Web-based instruction and evaluation, distributed and adaptive learning, CSCL, CSCW, interaction analysis, and grid technologies. He is co-director of the DPCS Research Laboratory [http://dpcs.uoc.es/]. Fatos Xhafa (fatos.xhafa@gmail.com) received his PhD in computer science from the Polytechnic University of Catalonia (Spain), where he currently is an associate professor in the Department of Languages and Informatics Systems. His research interests include parallel algorithms, combinatorial optimization, approximation and meta-heuristics, distributed programming, and grid and P2P computing. He has published in leading international journals and has served on the organizing committees of many conferences and workshops. He is also a member of the editorial board of several international journals including the International Journal of Computer-Supported Collaborative Learning, Grid and Utility Computing and Autonomic Computing. Santi Caball��� (scaballe@uoc.edu) has a PhD, master���s degree and bachelor���s degree in computer science from the Open University of Catalonia (Spain). He is an associate professor and a researcher in the Department of Computer Sciences, Multimedia and Telecommunication of the Open University of Catalonia, where he coordinates several online courses in the areas of software engineering, computer supported collaborative learning and information systems. His research focuses on e-learning and computer-supported collaborative learning, software engineering, and distributed and grid technologies.