Institution: | (1) Department of Mathematics and Statistics, Rochester Institute of Technology, Rochester, NY 14623, USA , US;(2) Department of Mathematics, Vanderbilt University, Nashville, TN 37240, USA michael.d.plummer@vanderbilt.edu , US;(3) Department of Mathematical Sciences, Middle Tennessee State University, Murfreesboro, TN 37132, USA xzha@.mtsu.edu, US |