https://hal.ird.fr/ird-00369126 Contributor : Francine DelmasConnect in order to contact the contributor Submitted on : Wednesday, March 18, 2009 - 2:43:03 PM Last modification on : Friday, February 23, 2018 - 6:10:05 AM Long-term archiving on: : Tuesday, June 8, 2010 - 8:30:20 PM