instant Sigmoid Emax effect model. Effect E is calculated using an equation

          Emax * c^h

E = E0 + -----------

          c50^h + c^h

where c is the free concentration (either tissue or blood/plasma, depending on the switch) at the BloodTissueConcentrationPort connector.

E0 - baseline effect without drug influence

Emax - maximal effect caused by drug

c50 - concentration producing half maximum effect

h - hill coefficient