Guido Guerceri, technician of the Math Department, fond of video, hard and experienced worker. Without him, I would not even thought to all of this.

The dean of the Science Faculty, Mauro Giannini, who encouraged this enterprise.

My colleague from Chemistry, Marina Rui: we started together on similar roads, initially parallel, but then quickly converging (much faster that the "convergenze parallele" of Aldo Moro).

All of the students that have collaborated, for their essential contribution: Federico Boccardo, Debora Carozzo, Andrea Squarcia and Riccardo Traverso.

I would like to thank also people who are not directly involved in this project, but that helped or encouraged me at essential steps: Roberto Cianci, Ignacio Garcia-Jurado, Chiara Gazzolo, Roberto Gazzolo, Stefano Moretti, Pier Angelo Mori.