说明：  also to thank Christian Brandt for his enthusiasm and his remarkable motivation and for all the help he could bring especially in the medical context. My great thanks to the Alsace region for agreeing to finance this work of thesis. I thank my rapporteurs, Laurent Daudet and Olivier Meste, for accepting the heavy rapporteur and paid close attention to my manuscript. I thank also Jean Merckle for agreeing to preside over my