1. ICAR, National Research Council (CNR), Palermo, Italy;
2. Institute of Physics and Astronomy, Universität Potsdam, Potsdam, Germany;
3. Dipartimento di Scienze Molecolari e Nanosistemi (DSMN) and European Centre for Living Technology (ECLT), Ca’ Foscari University of Venice, Venezia, Italy;
4. MIRMI, Technische Universität München, Munich, Germany
5. Department of Mathematics and Statistics, Georgia State University, Atlanta, USA;
6. Department of Mathematics, Public University of Navarre, Pamplona-Iruñea, Spain