DC--Transport in Quantum Wires

The influence of electron--electron interaction on two terminal DC conductance of one--dimensional quantum wires is studied. A cancelation between the effect of the electron--electron interaction on the current and on the external electric field is the reason for the universal value, $e^2/2\pi\hbar $ per mode, of the DC conductance of a clean wire. The effect of the renormalization of the electric field on the DC conductance in the presence of an interplay between the electron--electron interaction and backward scattering due to an impurity is considered.