1. Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia 26506, USA
2. Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
3. Dipartimento di Fisica, Università degli studi di Roma “Tor Vergata,” 00133 Roma, Italy
4. Centro de Física, Universidade do Minho, P-4710-057 Braga, Portugal
5. Instituto de Polímeros e Compósitos, Universidade do Minho, P-4800-058 Guimarães, Portugal