Stretched polymers: single-stranded DNA

Magnetic tweezer studies of the force-elongation of single stranded DNA at various salt concentrations by the Saleh group at UCSB have discovered several distinct scaling regimes.  At relatively high forces, an unusual behavior is observed where L is the end-to-end length and f is the applied force.  I shall review our understanding of these scaling properties with a speculation concerning the logarithmic behavior in analogy to one dimensional ferromagnets.