Hines, Michael and Peter Shrager (1991). A computational test of
the requirements for conduction in demyelinated axons.
J. Restorative Neurology and Neuroscience. 3 81--93.

This example produces figure 3 of the paper.  The implementation is
derived from the paper and is not based on the original code. 
Discrepancies in minor quantitative details are those that depend on a
few tenths of a degC changes in celsius.  The current version of NEURON
(v5.2) does not allow use of secondorder=2 in the presence of the
extracellular mechanism.