1. Department of Theoretical Physics, Eötvös University, H-1117 Budapest, Pázmány sétány 1/A, Hungary, Department of Biochemistry, Eötvös University, H-1088 Budapest, Puskin utca 3, Hungary, and Department of Plant Taxonomy and Ecology, Eötvös University, H-1083 Budapest, Ludovika tér 2, Hungary