1. University of Chieti-Pescara, Viale Pindaro 42, 65127 Pescara, Italy. fioravanti@sci.unich.it
2. University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy. pettorossi@disp.uniroma2.it
3. IASI-CNR, Viale Manzoni 30, 00185 Rome, Italy. maurizio.proietti@iasi.cnr.it
4. IMT Institute for Advanced Studies Lucca, Piazza San Ponziano 6, 55100 Lucca, Italy. valerio.senni@imtlucca.it