Doppler ultrasound is a type of ultrasound that depends on the Doppler Effect, a change in the wave's frequency, which can occur from the motion of a reflector, such a red blood cell. We experience the Doppler Effect when, for example, an ambulance approaches us, passes and then drives away.
Definition of PLACODERM. : any of a class (Placodermi) of extinct chiefly Devonian fishes with an armor of bony plates and primitive jaw structures.ADVERTISEMENT. New Latin Placodermi, ultimately from GK plak-, plax + derma skin â more at derm-. any of a class (Placodermi) of extinct chiefly Devonian fishes with an armor of bony plates and primitive jaw structures. ADVERTISEMENT.
Draco, or the Dragon, is a constellation in the northern hemisphere. It was first charted by the Greek astronomer Ptolemy in the 2nd century. In ancient Egypt, the constellation was called Tawaret, after the vigilant, protective goddess of the northern sky, whose body was depicted as part-human, part-lioness, part-crocodile and part-hippopotamus.