1. INRIA, Team Aviz, Université Paris-Sud, Bât 490, 91405 Orsay, France.
2. School of Electrical and Computer Engineering, Purdue University, 465 Northwestern Avenue, West Lafayette, IN 47907-2035, USA.
3. Northwest National Laboratory, Richland, WA 99352, USA.
4. Department of Computer Science, University of Kaiserslautern, 67663 Kaiserslautern, Germany.
5. Department of Computer Science, 2063 Kemper Hall, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.