Teen Repellent.

• Position: TECHNOLOGY - Mosquito anti-vandalism device

An anti-vandalism device aimed at teens has started a heated debate in Philadelphia. Thirty one of the city's public spaces are equipped with a speaker called the Mosquito, which emits a high-pitched noise that theoretically only those under 25 can hear. * (Some older people, however, say they still hear it.) Officials point out that the devices are just on at night to prevent loitering--but critics say it's age-based discrimination. In response to public outrage, the city has halted new installations of the device, pending a comprehensive review. This isn't the first time the Mosquito has sparked a dispute; transit officials in Washington, D.C., removed the devices from a...