A ladder resistor includes a first resistor group including a number of resistors connected in series and generating a number of reference voltages, and a second resistor group including a same number of resistors connected in series as the plurality of resistors included in the first resistor group, and generating a number of reference voltages. The control system determines an unstable operating condition in response to signals indicating the motor current or power consumption of each compressor and the position of the pre-rotation vanes of the compressors. An average of the difference between the present value distribution of contingent future benefits and the present value of the contingent future investment is determined. If the MS is the last one receiving the broadcast service from the BS, the BS terminates the broadcast service upon receipt of the location registration message. Front and rear fender assemblies can be attached to the frame by a midpoint fastener passing through respective apertures in each of the front and rear fender assemblies, through a grommet, and into the frame. The light source may be oriented at Brewster’s angle to the polarizer to improve polarization contrast.