1. The Institute for Scientific Computing and Applied Mathematics, Indiana University, Bloomington, IN, USA. E-mails: aimhuang@indiana.edu, temam@indiana.edu
2. Laboratoire de Mathématiques et Applications, Université de Poitiers, Futuroscope Chasseneuil cedex, France. E-mail: Madalina.Petcu@math.univ-poitiers.fr
3. The Institute of Mathematics of the Romanian Academy, Bucharest, Romania