1. Natural Sciences Department, LaGuardia Community College of The City University of New York, 31-10 Thomson Ave, Long Island City, NY 11101, USA
2. Physics Department and CSCU Center for Nanotechnology, Southern Connecticut State University, 501 Crescent Street, New Haven, CT 06515, USA
3. Department of Mathematics, College of Staten Island of The City University of New York, 2800 Victory Blvd, Staten Island, NY 10314, USA