a
Research Unit, Drägerwerk AG & Co. KGaA, Moislinger Allee 53-55, 23542 Lübeck, Germany
b
Institute of Electrical Engineering and Measurement Technology, Leibniz University Hannover, Appelstr. 9a, 30167 Hannover, Germany
c
Physics Department, German University in Cairo, Entrance El Tagamoa El Khames, New Cairo City, Egypt
E-mail: frank.gunzer@guc.edu.eg
;
Fax: +202 7581 041
;
Tel: +202 7589 990 8