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.
Interestingly, Dodge claims that the longer, four-door body of the Charger Hellcat endows it with better aerodynamic properties than its Challenger coupe analog and thus allows an even higher top speed: a hellaciously fast and aero-limited 204 mph.