1. Institute for Nonlinear Science and
2. Balaton Limnological Research Institute of the Hungarian Academy of Sciences, H-8237 Tihany, Hungary; and
3. Instituto de Fisica da Universidade de Sao Paulo, 05315-970, Sao Paulo, Brazil
4. Department of Physics and Marine Research Laboratory, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0402;