A system for controlling, a response to an operator, a consist of at least first and second locomotives having discrete operating modes. In one embodiment, the apparatus may include a joist rim having a web and first and second rim legs extending substantially perpendicularly from the web. In an exemplary embodiment, the control circuit modulates a current provided to the solid state lighting in response to a predetermined minimum current level parameter and a predetermined peak current level parameter, such that the DC average current level is substantially proportional to one-half of a sum of a predetermined peak current level and a predetermined minimum current levelIM\u2061. The robust Schmitt trigger based memory cell exhibits built-in process variation tolerance that gives tight SNM distribution across the process corners. The invention further relates to a particulate material metering andor feed system comprising the valve assembly. Avoiding the use of a static session key during encryption offers several advantages over existing encryption methods.