A system and method for controlling fuel delivery through a fuel injection system to an internal combustion engine is described. The screw has a through bore with two bore portions differing in diameter. Application of an electric current of 100 mA to the diode causes a phase difference of 122 degrees and an amplitude ratio of 1. The low and high ranked paths are selected from this ranked list as the first set of diverse paths through the network. An apparatus for performing a cluster assay comprises means for accommodating a sample and means for applying a rotating magnetic field, the magnetic field being adapted for selectively actuating clusters of superparamagnetic particles.