Access recirculation in a shunt is determined quantitatively by a method in which a standard solution, such as a saline, is injected into a patient’s bloodstream upstream of the shunt. The apparatus may further include a data de-duplication module operable on the processor to read a signature of incoming data, compare the signature to first data in the non-volatile random access memory, and flag the incoming data for discard when the signature indicates a match to the first data. 0 parts by mass; an elastomer having an average particle diameter of 10 to 800 nm in an amount of 1 to 10 parts by mass based on 100 parts by mass of the ethylene-propylene random copolymer; and a crystalline nucleating agent, and in which after kneading thereof, the kneaded propylene resin composition exhibit a melt flow rate of 0. In certain embodiments, the stopper member includes a mechanical linkage for coupling it to the fixing member, and surface features that resist withdrawal of the fixing member from the bone.