https://cel.archives-ouvertes.fr/cel-00649641 Contributor : Sylvie FloresConnect in order to contact the contributor Submitted on : Thursday, December 8, 2011 - 12:48:02 PM Last modification on : Thursday, December 8, 2011 - 2:40:23 PM Long-term archiving on: : Friday, March 9, 2012 - 2:31:55 AM