https://cel.archives-ouvertes.fr/cel-00343873 Contributor : Laurent ChusseauConnect in order to contact the contributor Submitted on : Wednesday, December 3, 2008 - 1:35:51 AM Last modification on : Wednesday, September 15, 2021 - 11:02:02 AM Long-term archiving on: : Thursday, October 11, 2012 - 12:31:30 PM