1. Department of Nursing, Gifu College of Nursing, Hashima, Gifu , 501-6295, Japan
2. Department of Mathematical Sciences, Graduate School of Engineering, Osaka Prefecture University, Naka-ku, Sakai, Osaka , 599-8531, Japan
3. Department of Mathematical and Statistical Methods, Poznan University of Life Sciences, Wojska Polskiego 28, PL-60-637 Poznan , Poland