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.
The pitch is used often by the pitcher to get ahead in the count or when he needs to throw a strike. This type of fastball is intended to have minimal lateral movement, relying more on its velocity. It is often perceived as the fastest pitch a pitcher throws, with recorded top speeds above 100 mph. The fastest pitch recognized by MLB was on September 25, 2010, at Petco Park in San Diego by then Cincinnati Reds left-handed relief pitcher Aroldis Chapman. It was clocked at 105.1 miles per hour. April 19, 2011 Chapman lit up the stadium radar gun at 106 MPH (the TV-reading had his pitch at 105 MPH, and the pitchF/X reading was actually 102.4 MPH).