Four-terminal sensingIn electrical engineering, four-terminal sensing (4T sensing), 4-wire sensing, or 4-point probes method is an electrical impedance measuring technique that uses separate pairs of current-carrying and voltage-sensing electrodes to make more accurate measurements than the simpler and more usual two-terminal (2T) sensing. Four-terminal sensing is used in some ohmmeters and impedance analyzers, and in wiring for strain gauges and resistance thermometers. Four-point probes are also used to measure sheet resistance of thin films (particularly semiconductor thin films).
Portable media playerA portable media player (PMP) (also including the related digital audio player (DAP)) is a portable consumer electronics device capable of storing and playing digital media such as audio, images, and video files. The data is typically stored on a compact disc (CD), Digital Versatile Disc (DVD), Blu-ray Disc (BD), flash memory, microdrive, SD cards or hard drive; most earlier PMPs used physical media, but modern players mostly use flash memory.
Electroreception and electrogenesisElectroreception and electrogenesis are the closely related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes (most famously the electric eel, which is not actually an eel but a knifefish) to stun prey. The capabilities are found almost exclusively in aquatic or amphibious animals, since water is a much better conductor of electricity than air.
AgeismAgeism is discrimination against individuals or groups on the basis of their age. The term was coined in 1969 by Robert Neil Butler to describe discrimination against seniors, and patterned on sexism and racism. Butler defined "ageism" as a combination of three connected elements. Originally it was identified chiefly towards older people, old age, and the aging process; discriminatory practices against older people; and institutional practices and policies that perpetuate stereotypes about elderly people.
Electric organ (fish)In biology, the electric organ is an organ that an electric fish uses to create an electric field. Electric organs are derived from modified muscle or in some cases nerve tissue, and have evolved at least six times among the elasmobranchs and teleosts. These fish use their electric discharges for navigation, communication, mating, defence, and in strongly electric fish also for the incapacitation of prey. The electric organs of two strongly electric fish, the torpedo ray and the electric eel were first studied in the 1770s by John Walsh, Hugh Williamson, and John Hunter.
