  The validity of the Second Law of thermodynamics, indisputable in the
macroscopic world, is challenged at the mesoscopic level: a mesoscopic isolated
system, possessing spatial dimensions of the order of a few microns, is
capable, as shown by a straightforward kinetic analysis, to exhibit a perpetuum
mobile behavior associated with large negative variations of the Clausius
entropy of the system. This violation of the Second Law is expedient for
devising a cyclic process through which an isolated system can extract energy
from a surrounding thermal bath.
