The present disclosure provides apparatuses, systems, and methods involving a spotter for depositing a substance on a submerged surface. A plurality of fiber optic monitoring assemblies are located proximate a section of railroad tracks. The baffle retards intake blow back, thereby reducing noise generated by the engine. The techniques also include extensions to the LDP that enable a router to advertise upstream label assignment capability to neighboring routers in the network. No substantial amount of the dynamic magnetic flux passes through the radial air gaps.