1. Department
of Physics, University of Illinois at Urbana−Champaign, Urbana, Illinois, United States
2. Center
for Biophysics and Computational Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois, United States
3. The Howard Hughes Medical Institute, Chevy Chase, Maryland, United States
4. Beckman
Institute for Advanced Science and Technology, University of Illinois at Urbana−Champaign, Urbana, Illinois, United States