{TAIL ~ The vent position} can be changed from {HEAD ~ an equilibrium position} to a nonequilibrium position 
{ TAIL ~ The vent position } can be changed from { HEAD ~ an equilibrium position } to a nonequilibrium position
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH