the strength and direction of chemotaxis. If and , then is negative, increasing the probability of accepting the index copy in equation . The net effect is that the cell moves up the field gradient with a velocity . If is negative, the opposite occurs, and the cell will move down the field gradient. Plugins with more sophisticated calculations (e.g., including response saturation) are available within CompuCell3D (see the CompuCell3D User Guide).
the strength and direction of chemotaxis. If 
and 
, then 
. If 
is negative, 
