1. Department of Mathematics, Tufts University, Bromfield-Pearson Hall, Medford, MA 02155, USA ()
2. Air Force Research Laboratory, Hanscom AFB, MA 01731, USA ()
3. Centre for Computational Science, Queen Mary, University of London, Mile End Road, London E1 4NS, UK ()
4. Department of Materials Science, Massachusetts Institute of Technology, Cambridge, MA 02138, USA ()