1. University of Chieti-Pescara, Pescara, Italy. fioravanti@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, Italy. valerio.senni@imtlucca.it