A thin film magnetic head includes a medium projection detection mechanism that detects a projection on the surface of a recording medium. One aspect of the invention involves a method at a computer associated with an ad placement provider. The transducer includes a two-dimensional transducer element matrix array formed by a plurality of individually controllable transducer elements. The method uses a knowledge repository of phases and scripts. The n-type and p-type regions in contact with the active region are disposed between the n-type and p-type regions.