1. University of Bergamo, Piazzale S. Agostino 2, P.O. Box 24129, Bergamo, Italy
2. Villa Santa Maria Institute, IV Novembre, P.O. Box 22038, Tavernerio, Italy
3. Semeion, Research Centre of Sciences of Communication, Via Sersale 117, P.O. Box 00128, Rome, Italy
4. Department of Mathematical and Statistical Sciences, University of Colorado at Denver, P.O. Box 173364, Denver, CO, USA
5. School of Electronic and Information Engineering, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing, China
6. Division of Cardiology, Cardiocentro Lugano CH-6900, Switzerland
7. Center of Research on Psychology in Somatic Diseases, CoRPS, Tilburg University, Warandelaan 2, P.O. Box 90153, 5000 LE Tilburg, The Netherlands