1. Department of Industrial Engineering; University of Trento; via Sommarive 9 38123 Trento Italy
2. Department of Computer Science; University of Verona; Ca' Vignal 2, Strada le Grazie 15 37134 Verona Italy
3. Department of Physics; University of Padua; via Marzolo 8 35131 Padova Italy
4. ERAMET-RESEARCH-SLN; 1 Avenue Albert Einstein 78190 Trappes France
5. GEOPS; Université Paris Sud; Bât 504 91405 Orsay Cedex France
6. Department of Physics; University of Trento; via Sommarive 14 38123 Trento Italy