1. Center for Mathematical Plasma Astrophysics, Department of Mathematics, K.U. Leuven (University of Leuven), Celestijnenlaan 200B, B-3001 Leuven, Belgium
2. PDC Center for High Performance Computing, KTH Royal Institute of Technology, Teknikringen 14, 10044 Stockholm, Sweden
3. Center for Integrated Plasma Studies, University of Colorado Boulder, Gamow Tower, Boulder, Colorado 80309-0390, USA