1. Faculty
of Science, J. E. Purkinje University, 400 96 Ústí
nad Labem, Czech Republic
2. Institute
of Chemical Process Fundamentals, Academy of Sciences, 165 02 Prague 6, Czech Republic
3. Department
of Mathematics and Statistics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
4. Faculty
of Science, University of Ontario Institute of Technology, Oshawa, Ontario L1H 7K4, Canada