A periodontist is a dentist who specializes in the prevention, diagnosis, and treatment of periodontal disease, and in the placement of dental implants. Periodontists are also experts in the treatment of oral inflammation.
Ground speed. Ground speed is the horizontal speed of an aircraft relative to the ground. An aircraft heading vertically would have a ground speed of zero. Information displayed to passengers through the entertainment system often gives the aircraft ground speed rather than airspeed.
But Consumer Reports has changed the ground rules: While the federal government requires a 30 mph frontal crash for car seats, Consumer Reports ran it at 35 mph and 38 mph for side-impact crashes, the same speeds used for new car tests.