Helder, M. [P:(DE-HGF)0] ; Strik, D.P.B.T.B. [P:(DE-HGF)0] ; Hamelers, H.V.M. [P:(DE-HGF)0] ; Kuhn, A. J. [P:(DE-Juel1)129349] ; Blok, C. [P:(DE-HGF)0] ; Buisman, C.J.N. [P:(DE-HGF)0]