In one embodiment, {HEAD ~ one or more additional sensors} are integrated or coupled to {TAIL ~ a hydration sensor} 
In one embodiment , { HEAD ~ one or more additional sensors } are integrated or coupled to { TAIL ~ a hydration sensor }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL