1. Department of Mathematics, Center for Research in Scientific Computation, North Carolina State University, Raleigh, NC, USA
2. Department of Mathematics, Youngstown State University, Youngstown, OH, USA
3. Department of Mathematics, Mount Holyoke College, South Hadley, MA, USA
4. Department of Mathematics, University of St. Andrews, St Andrews, Fife, Scotland, UK
5. Nondestructive Evaluation Science Branch, NASA Langley Research Center, Mail Stop 231, Hampton, VA, USA