1. Field
of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853, United States
2. Department of Chemical & Biomolecular Engineering and Bioengineering Program, Lehigh University, 111 Research Drive, Bethlehem, Pennsylvania 18015, United States
3. Department
of Mathematics, Cornell University, Ithaca, New York 14853-4201, United States