1. Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-1593, USA
2. Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05, France
3. Qatar Environment and Energy Research Institute, Qatar Foundation, P.O. Box 5825, Doha, Qatar