1. Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, United States
2. T. C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
3. Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
4. Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States