{TAIL ~ A width Pb} of the bottom portion of each protrusion formed between the striations and {HEAD ~ a width Wb} of the lower base satisfy Pb<Wb 
{ TAIL ~ A width Pb } of the bottom portion of each protrusion formed between the striations and { HEAD ~ a width Wb } of the lower base satisfy Pb < Wb
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH