1. Department of Mathematics & SRM Research Institute, SRM Institute of Science and Technology, Kattankulathur 603 203, Tamil Nadu, India
2. Aquatic Bioresource Research Laboratory, Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700 019, India
3. Department of Mathematics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, India