Spieker, E. [P:(DE-HGF)0] ; Hollensteiner, S. [P:(DE-HGF)0] ; Jäger, W. [P:(DE-HGF)0] ; Haselier, H. [P:(DE-Juel1)VDB26000] ; Schroeder, H. [P:(DE-Juel1)VDB3130]