The present invention provides improved dietary supplements and methods for inhibiting the progression of macular degeneration and promoting healthy vision. Each measurement session includes applying an external electromagnetic field to the measurement locations, detecting at least two responses of the measurement location, and generating data indicative of the detected response. From the physical media libraries, the media library controller can establish a virtual media library and associate a host with the virtual media library. Systems, methods, and kits are also provided that use a synthetic receptor. In general, the indicator is associated with an article to convey information about the article. The chemical delivery system may also be provided with an efficient and conveniently located heater system for heating the chemical delivery system cabinet.