Department of Mathematics, Center for Industrial Mathematics, University of Bremen, Bremen, Germany.|Department of Mathematics, Center for Industrial Mathematics, University of Bremen, Bremen, Germany.|Department of Mathematics, Center for Industrial Mathematics, University of Bremen, Bremen, Germany.|Department of Mathematics, Center for Industrial Mathematics, University of Bremen, Bremen, Germany.|Department of Mathematics, Center for Industrial Mathematics, University of Bremen, Bremen, Germany.|Department of Mathematics, Center for Industrial Mathematics, University of Bremen, Bremen, Germany.