  We present a detailed study of the conduction properties of a molecular wire
where hopping processes between electronic sites are coupled to a vibrational
mode of the molecule. The latter is sandwiched between two electronic leads at
finite temperatures. We show that the electro-mechanical coupling can lead to a
strong enhancement of the lead-to-lead conduction. Moreover, under suitable
driving of the molecular vibrational mode, the device can act as a transistor
passing sharply from enhanced conduction to short-circuit configuration.
