Before revision:  The analytical result can be used as an alternative method to infer the contour length and persistence length of polymers by measuring their average extension and longitudinal fluctuations along the stretching (force ) direction. It also provides an additional criterion to check the region of validity of the WLC model .
After revision:  Finally we apply our results to recent experimental observations that revealed the hitherto unknown periodic cytoskeleton structure of axons and measured the longitudinal fluctuations, and show how the comparison between our results and experiments limits possible local configurations and dynamics of the spectrin tetramers in the axonal cytoskeleton .