Brought about by the constant pressure of lying on a stationary surface, painful ulcers can involve substantial skin loss, sometimes exposing muscle and even bone.

Air pressure on the surface of the Earth is fairly constant, so in designing a microphone for use on land, engineers don't have to worry about large variations in air pressure.

While the pressure difference between the inlet of fracture and the outlet of fracture is constant, the transmissibility of fracture surface will decrease with the rising fractal dimension.