1. Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
2. CNRS EAC 7180, University of Paris VI, France
3. AG Neurosensorik/Animal Navigation, IBU, University of Oldenburg, Germany
4. FB Biowissenschaften, J. W. Goethe-Universität, Frankfurt am Main, Germany