any of a range of other devices to broadcast vibrations at the patient in order to attempt to heal them. Other notable quack devices in radionics have included the Ionaco and the Hieronymus machine. Some people claim to have the paranormal or parapsychological ability to detect "radiation" within the human body, which they call radiesthesia. According to the theory, all human bodies give off unique or characteristic "radiations" as do all other physical bodies or objects. Such radiations are often termed an "aura". Radiesthesia is cited as the explanation of such phenomena as dowsing by rods and pendulums in order to locate buried substances, diagnose illnesses, and the like. Radiesthesia has been described as a mixture of occultism and pseudoscience by critics. Modern practitioners conceptualize these devices merely as a focusing aid to the practitioner's proclaimed dowsing abilities, and claim that there is no longer any need for the device to have any demonstrable function. Indeed, Abrams' black boxes had no purpose of their own, being merely obfuscated collections of wires and electronic parts. Contemporary proponents of radionics or EMT claim that where there is an imbalance of electromagnetic fields or frequencies, within the body, that it causes diseases or other illnesses by disrupting the body's chemical makeup. These practitioners believe that applications of electromagnetic energy from outside the body can correct these imbalances. Like magnet therapy, electromagnetic therapy has been proposed by practitioners of alternative medicine for a variety of purposes, including, according to the American Cancer Society, "ulcers, headaches, burns, chronic pain, nerve disorders, spinal cord injuries, diabetes, gum infections, asthma, bronchitis, arthritis, cerebral palsy, heart disease, and cancer". Another variant of radionics or EMT is magnetic resonance therapy. Scientific assessment The claims for radionic devices contradict the accepted principles of biology and physics. No scientifically verifiable mechanisms of function for these devices has been posited, and they are often described as "magical" in operation. No plausible biophysical basis for the "putative energy fields" has been proposed, and neither the fields themselves nor their purported therapeutic effects have been convincingly demonstrated. No radionic device has been found efficacious in the diagnosis or treatment of any disease, and the U.S. Food and Drug Administration does not recognize any legitimate medical uses of any such device. According to David Helwig in The Gale Encyclopedia of Alternative Medicine, "most physicians dismiss radionics as quackery". Internally, a radionic device is very simple,