Abstract: A hydration system comprises a bladder assembly defining a bladder chamber, a hose assembly, and a heating system comprising a heating element defining a loop portion. Liquids flow from the bladder chamber to the hose assembly. The loop portion is arranged within the hose assembly such that current flowing through the heating element inhibits freezing of liquids within at least a portion of the hose assembly.

Abstract: Methods and systems are provided that extend the functionality of electro-optical sensors. A device has a multiple light sources, a light detector, and a processor configured to operate the light sources and the light detector to perform distinct functions. At least one of the distinct functions includes a biometric identification function in which light is propagated from the plurality of light sources through presented material. The propagated light is received with the light detector, with the presented material being identified from the received light. Another of the distinct functions includes a nonidentification function performed with the light sources and the light detector.