A photovoltaic string may include an open circuit voltage limiter that conducts current in one direction to provide a limiter voltage less than an open circuit voltage of the photovoltaic string, and that conducts current in the other direction. As a multiplexer, the device functions to spatially combine the optical signals from several laser sources and launch the spatially combined laser beams into a single optical fiber. The therapy device is able to readily convert from supination therapy to pronation therapy. The magnetic ring, acting as a debris collector, collects debris from the air bearing to prevent deterioration of the air journal bearing. The carbon nanostructures exhibit high surface area, high porosity, high graphitization, and facilitate mass transfer and electron transfer in fuel cell reactions. The processor calculates an estimated weight and updates the display which displays the estimated weight, based on forces measured between the time a fish strikes the hook and the landing of the fish.