Þ þ L HP . Then however, one needs to fit the section of the force versus extension curve up to the unfolding event with a worm-like chain model in order to compute the extension of the handles, x H F 2 ð Þ at F 2 . When performing this more laborious analysis on a subset of our data, we only find a 1-2 nucleotide difference in contour length compared to the analysis that utilizes the applied approximation