Periodontal treatment is the specialist cleaning of your teeth and gums to help control the bacteria that cause gum disease. Gum disease is caused by the germs (bacteria) which live in your mouth. The bacteria stick to your teeth, irritate the gums and make them bleed.
(Redirected from Ground effect in aircraft) In fixed-wing aircraft, ground effect is the increased lift (force) and decreased aerodynamic drag that an aircraft's wings generate when they are close to a fixed surface. When landing, ground effect can give the pilot the feeling that the aircraft is floating.
Observer effect (physics) For other uses, see Observer effect. In physics, the term observer effect refers to changes that the act of observation will make on a phenomenon being observed. This is often the result of instruments that, by necessity, alter the state of what they measure in some manner.