The force on a disclination in a liquid crystal

It is argued that the Peach-Koehler force on a disclination in a nematic liquid crystal is, unlike its namesake for a dislocation in a solid, not a fictitious configurational force, but a real force which, for equilibrium, must be balanced by an external force applied to the singular line. Formally this is a consequence of the near identity of the Ericksen stress and the appropriate energy-momentum tensor.