A means and method for treating malaria, schistosomiasis, and cancer using a spiro or dispiro 1,2,4-trioxolane is described. The resistive switching circuit can be operable to accept an input voltage Vg, and provide a resistance response Rrs that corresponds to the input signal Vg. When a request for an itemservice is received by the ESA from a customer, the customer profile information is retrieved from the customer database. The ads may be selected using demographic or common channel preference pattern information associated with the set top box. In one example approach, a dual path purge system for an engine comprises an ejector including a restriction, first and second inlets, and an outlet, at least one break-point at the restriction or inlets, and a shut-off valve coupled to the outlet.