Stefanella Boatto,  
email: sboatto@fields.utoronto.ca, sboatto@math.mcmaster.ca 
address: 
Fields Institute for research in Mathematical Sciences, 222 College Street,  Toronto, Ontario M5T 1J3, Canada 
Dept. of Mathematics and Statistics, McMaster University, Hamilton, Ontario L8S..., Canada 
Carles Simo 
email: carles@maia.ub.es 
address: 
Dept. de Matematica aplicada i Analisi, Universitat de Barcelona, Gran Via de les Corts Catalanes 585, Barcelona 08007, Spain