Before revision: We  report calculations of position- and size-dependent opening probabilities for bubbles in double-stranded DNA . Our results are obtained from transfer-matrix solutions of (i) the Zimm-Bragg model for unconstrained DNA and of (ii) a self-consistent linearization of the Benham model for DNA under a superhelical constraint .
After revision: We present a general framework to study the thermodynamic denaturation of double-stranded DNA under superhelical stress. We report calculations of position- and size-dependent opening probabilities for bubbles in double-stranded DNA . Our results are obtained from transfer-matrix solutions of (i) the Zimm-Bragg model for unconstrained DNA and of (ii) a self-consistent linearization of the Benham model for DNA under a superhelical constraint .