1. Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine , Baltimore , MD 21205 , USA
2. Department of Biophysics, Graduate School of Science, Kyoto University , Japan
3. Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA; Howard Hughes Medical Institute , Baltimore , MD 21205 , USA
4. TC Jenkins Department of Biophysics, Johns Hopkins University , Baltimore , MD 21218 , USA