The model structure represents {HEAD ~ the patient response} with {TAIL ~ a time delay}, a time constant for response speed, and a nonlinear function for drug sensitivity 
with
The model structure represents { HEAD ~ the patient response } with { TAIL ~ a time delay } , a time constant for response speed , and a nonlinear function for drug sensitivity
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH