  A low energy crossover (see cond-mat/9711167) induced by Fermi liquid
reservoirs in transport through a 1D Mott-Hubbard insulator of finite length
$L$ is examined in the presence of impurity pinning. Under the assumption that
the Hubbard gap 2M is large enough: $M > T_L \equiv v_c/L$ ($v_c$: charge
velocity in the wire) and the impurity backscattering rate $\Gamma_1 \ll T_L$,
the conductance vs. voltage/temperature displays a zero-energy resonance.
Transport through a spin gapped 1D system is also described availing of duality
between the backscattered current of this system and the direct current of the
Mott-Hubbard insulator.
