1. Department of Physics, Emory University, Maths/Science Center, 400 Dowman Drive, Atlanta, GA 30322, USA
2. Biocomplexity Institute and Department of Physics and Biology, Swain Hall West 159, 727 East Third Street, Indiana University, Bloomington, IN 47405, USA
3. Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, USA