Adjusting the operating parameter could be based on a difference between a measured anisotropy of {TAIL ~ the first surface} and a measured anisotropy of {HEAD ~ the second surface} 
Adjusting the operating parameter could be based on a difference between a measured anisotropy of { TAIL ~ the first surface } and a measured anisotropy of { HEAD ~ the second surface }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD