This invention provides for an off-the-record e-mail system that can ensure that messages, particularly sensitive messages, are available only for the intended recipient and never reside on permanent storage media. In a circuit having two processors coupled by a data bus, the processors each learn that the other is capable of operating at a modified data rate. A high frequency filter can be interposed between the coupler and the 240 volt appliance to prevent noise from the appliance from entering the communication signal and for preventing communication signals from entering the appliance. In a specific embodiment, the concentration of charge-carrier dopant impurity atoms of the two portions are different from one another at the interface. These methods increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.