Of the common causes for exudative pleural effusions, parapneumonic effusions have the highest diagnostic priority. Even in the face of antibiotic therapy, infected pleural effusions can rapidly coagulate and organize to form fibrous peels that might require surgical decortication.
Retrogradation is the landward change in position of the front of a river delta with time.etrogradation is the landward change in position of the front of a river delta with time.
Retrograde motion is the apparent motion of a planet to move in a direction opposite to that of other bodies within its system, as observed from a particular vantage point. Direct motion or prograde motion is motion in the same direction as other bodies.rom the surface of Mars it appears to move in the opposite direction because its orbital period is less than a Martian day. There are also smaller numbers of truly retrograde artificial satellites orbiting Earth which counter-intuitively appear to move westward, in the same direction as the Moon.