1. Nonlinear
Physics Center, Australian National University, Canberra, ACT 2601, Australia
2. Department
of Physics, Queens College of The City University of New York, Queens, New York 11367, United States
3. Department
of Physics, The Graduate Center of The City University of New York, New York, New York 10016, United States
4. Institute of Applied
Physics of the Russian Academy of Science, Nizhny
Novgorod 603950, Russia