Stretching semiflexible polymers: Gibbs versus Helmholtz ensembles

What differences in behavior can one draw between the measurable quantities in fixed-force and fixed-extension experiments on semiflexible polymers (such as DNA), stretched by applying a force? The marked difference between the two types of experiment, represented by two different scaling curves as a function of a reduced stretching force and reduced extension, is revealed here. Potential regions of the parameter space that could benefit from further experimental investigation are also suggested.