In one implementation, an image sensor is calibrated by determining a spectral characterization for each image window of an image sensor, correlating the spectral characterization for each image window of the image sensor with a spectral property of a target illuminant, and generating a scale factor for each image window of the image sensor. The present invention employs signal strength measurements on N number channels of the frequency hopping scheme to determine M number of channels to be avoided. However, if the present embodiment arbitration software detects a HotSync Request received via the serial COM port, it runs the HotSync Manager enabling a HotSync process to occur between a personal digital assistant and the computer. The load reduction is performed by rapidly shutting-off power to the ports in the lower priority state while maintaining power to the ports in the higher priority state. The compositions of the invention can further comprise at least one penetration enhancer, at least one compound that donates, transfers or releases nitric oxide, elevates endogenous levels of endothelium-derived relaxing factor, stimulates endogenous synthesis of nitric oxide or is a substrate for nitric oxide synthase andor at least one vasoactive agent. A door hingedly attached to the side of the cover allows access to the interior of the structure.