Institution: | aUniversité Libre de Bruxelles (ULB), CP212, Bld. du Triomphe, 1050 Brussels, Belgium;bUniversitat Politècnica de Catalunya, Jordi Girona 1–3, E-08034 Barcelona, Spain;cSmith College, Northampton, MA 01063, USA;dUniversidad de Valladolid, Spain |