[1] Max Planck Inst Stromungsforsch, D-37073 Gottingen, Germany
[2] Univ Gottingen, Inst Nichtlineare Dynam, D-37073 Gottingen, Germany
[3] Tech Univ Dresden, Inst Theoret Phys, D-01062 Dresden, Germany
[4] European Mol Biol Lab, D-69117 Heidelberg, Germany