1. Department of Physics, Saratov State University, Astrakhanskaya str. 83, 410012 Saratov, Russia
2. Institute of Mathematics and Centre for Medical and Biotechnical Research, NAS of Ukraine, Tereshchenkivska St. 3, 01030 Kyiv, Ukraine
3. Forschungszentrum Jülich, Central Institute of Engineering, Electronics and Analytics, Electronic Systems (ZEA-2), 52428 Jülich, Germany