Before revision:  Here we examine a specific microscopic description, introduced by Yan and Marko, which allows for disruption of base pairing (i.e., "melting" ) and consequently enhanced local flexibility.
After revision:  Here we examine a specific microscopic description, introduced by Yan and Marko, which allows for disruption of base pairing (i.e., a `melt' or `kink', generically an `excitation' ) and consequently enhanced local flexibility.