| http://www.w3.org/ns/prov#value | - That is called Radio Frequency Identification, or RFID.Large stores use similar technology to keep track of what???s on the shelves.The Washington researchers have a similar system, but their devices are not plugged in, and they don???t need batteries, so they are cheaper, smaller, and last much longer.The energy comes from wireless signals, such as from a TV or cellphone tower, which all transmit
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