https://cel.archives-ouvertes.fr/cel-00564306 Contributor : Frédéric TailladeConnect in order to contact the contributor Submitted on : Tuesday, February 8, 2011 - 4:03:08 PM Last modification on : Tuesday, February 8, 2011 - 5:03:29 PM Long-term archiving on: : Monday, May 9, 2011 - 3:16:15 AM