{HEAD ~ The melt circulation} through the conduits is caused by {TAIL ~ the difference} in the levels and densities of the melt in these vessels 
is caused by
{ HEAD ~ The melt circulation } through the conduits is caused by { TAIL ~ the difference } in the levels and densities of the melt in these vessels
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH