Lengthscales and cooperativity in DNA bubble formation Z. Rapti, A. Smerzi, K. Ø. Rasmussen, A. R. Bishop, C. H. Choi and A. Usheva Europhys. Lett., 74 3 (2006) 540-546 Published online: 24 March 2006 DOI: 10.1209/epl/i2005-10543-x