1. IKERBASQUE, Basque Foundation for Science, Bilbao, Basque Country, Spain and BCAM, Basque Center for Applied Mathematics, Mazarredo, Bilbao, Basque Country, Spain and Academic Colaborator at UPV/EHU
2. BCAM, Basque Center for Applied Mathematics, Mazarredo Bilbao, Basque Country, Spain and Institute of Mathematics, University of Warsaw, Warsaw, Poland