1. Centre for Nonlinear Phenomena and Complex Systems, Universite Libre de Bruxelles, CP 213, Campus Plaine, B-1050 Brussels, Belgium
2. National Technical University of Athens, Department of Electrical and Computer Engineering, Iroon Polytechniou 9, GR-15773, Zografou Campus, Greece
3. University of Ioannina, Department of Computer Science, P.O. Box. 1186, GR-45110, Ioannina, Greece
4. Foundation of Biomedical Research of the Academy of Athens, 4 Soronou Efesiou Str 11527 Athens, Greece
5. Athens Air Force and Veterans Hospital, Department of Cardiology, P. Kanellopoulos St, Athens, Greece