First Author:   Ons Jedidi CREM-CNRS ons.jedidi@univ-rennes1.fr   University of Rennes1, 7 place hoche, bureau 102 Rennes, 35065, France   (33) 2 23 23 73 71(Phone) (33) 2 23 23 73 71(Fax) Second Author: Jean Sébastien Pentecote CREM-CNRS, University of Caen - Low Normandy jean-sebastien.pentecote@unicaen.fr         http://