[1] Univ Delhi, Netaji Subhas Inst Technol, Fac Technol, Dept Math, New Delhi 110078, India
[2] Jamia Millia Islamia, Ctr Theoret Phys, New Delhi 110025, India
[3] Fukushima Univ, Fac Symbiot Syst Sci, Div Human Support Syst, Fukushima 9601296, Japan
[4] Univ Zululand, Dept Math Sci, ZA-3886 Kwa Dlangezwa, South Africa