1 AFib reduces the ability of the atria to pump blood into the ventricles, and usually causes the heart to beat too rapidly. 2  One-half million new cases of atrial fibrillation are diagnosed every year in the U.S., and billions of dollars are spent annually on its diagnosis and treatment.
noun, (used with a singular verb) 1. the branch of mechanics that deals with the motion of air and other gases and with the effects of such motion on bodies in the medium. Compare aerostatics (def 1). Origin of aerodynamics.
Aerodynamic drag is a function of frontal area and slickness of shape-the latter expressed as âcoefficient of drag,â or Cd-and it increases with the square of velocity. That means a truck burns more fuel at speed than a typical car simply because itâs big and blocky, and a whole bunch more at 75 mph than at 60 or 65.