A time of flight method to measure the speed of sound using a stereo sound card

We present an inexpensive apparatus for measuring the speed of sound, with a time of flight method, using a computer with a stereo sound board. Students measure the speed of sound by timing the delay between the arrivals of a pulse to two microphones placed at different distances from the source. It can serve as a very effective demonstration, providing a quick measurement of the speed of sound in air; we have used it with great success in Open Days in our Department. It can also be used for a full fledged laboratory determination of the speed of sound in air.Comment: Accepted for publication in The Physics Teache

Doença de Sturge-Weber atípica associada a angiomatose metamérica: registro de um caso e revisão da literatura

Um caso, possivelmente o primeiro, de doença de Sturge-Weber associada à hemangioma plano de distribuição metamérica no tronco e membros é descrito clinicamente. Achados radiológicos incluindo exames contrastados e tomografia axial computadorizada são descritos e discutidos. Comenta-se a relação entre os angiomas neurocutâneos