Stephan Dahlke is Professor in the Department of Mathematics and Computer Sciences at Philipps-University of Marburg, Germany.Filippo De Mari is Associate Professor in the Department of Mathematics at the University of Genova, Italy.Philipp Grohs is Assistant Professor in the Seminar for Applied Mathematics at the Swiss Federal Institute of Technology, Zurich, Switzerland.Demetrio Labate is Associate Professor in the Department of Mathematics at the University of Houston, TX, USA