Contributed to this work : Mwatha Ngalasso, Cynthia Fleury, Christine Deprez, Foued Laroussi, Fabien Liénard, Clément Mbom, Véronique Miguel Adissu, Isabelle Nocus, Jacques Vernaudon, Mirose Païa, Léonard Sam, Philippe Guimard, Agnès Florin, Michel Launey, Sara Greaves, Marie-Laure Schultze, Michel Lafon, Kutlay Yagmur and Sjaak Kroon.