Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, California, United States of America. volman@salk.edu|Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, California, United States of America. volman@salk.edu|Center for Theoretical Biological Physics, University of California at San Diego, La Jolla, California, United States of America. volman@salk.edu