A prosthetic foot incorporate a foot keel and a calf shank connected to the foot keel to form an ankle joint area of the prosthetic foot. The center rail has a toothed wheel and the two rolling body carriages each have one toothed rack that meshes with the toothed wheel. The input of the first delay element of the first chain is connected to the circuit input and the output of each delay element of the first delay chain is selectively connectable to the input of the th delay element of the second delay chain via a respectively associated switch of a first group of switches, wherein i=1. Provided are methods for testing subjects to ascertain health and disease status and to assess the risk of developing a disease or condition. The qualifier, upon a connection meeting the criteria, passes a trigger to the specific action function that performs the desired specific action.