  The transport through a barrier is studied for a Tomonaga-Luttinger liquid of
finite length connected to reservoirs. An effective action for the phase
variable at the barrier is derived for spatially varying electric field. In the
d.c. limit only the total voltage drop between the left and right reservoirs
appears in the action. We discuss crossovers of the renormalization group flow
and hence of the temperature and wire length dependence of the conductance,
taking into account the location of the barrier.
