The escape transition of a polymer: A unique case of non-equivalence between statistical ensemblesD. I. Dimitrov, L. I. Klushin, A. Skvortsov, A. Milchev and K. BinderEur. Phys. J. E, 29 1 (2009) 9-25DOI: https://doi.org/10.1140/epje/i2008-10442-0