1. Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Kosice, Slovakia
2. Faculty of Science, Pavol Jozef Safarik University, Park Angelinum 9, 04001 Kosice, Slovakia
3. Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Mala Hora 4, 03601 Martin, Slovakia