Atherosclerosis in the carotid arteries, two large arteries in the neck that carry blood to the brain, is a major risk factor for ischemic stroke. Symptoms of stroke include: 1  Sudden numbness, weakness, or paralysis of face, arm or leg, especially on one side of the body. carotid endarterectomy is a surgical procedure in which a doctor removes fatty deposits blocking one of the two carotid arteries, the main supply of blood for the brain.
Polar stratospheric cloud. Polar stratospheric clouds or PSCs, also known as nacreous clouds (/ËneÉªkriË.És/, from nacre, or mother of pearl, due to its iridescence), are clouds in the winter polar stratosphere at altitudes of 15,000â25,000 meters (49,000â82,000 ft).
This results in a thinning of the ozone layer, and in polar regions, a hole. The holes occur at the poles, and usually in Antarctica because of the extreme cold. During the winter polar stratospheric clouds form which are able to convert gases in the atmosphere into Cl (chlorine) and ClO (chlorine monoxide).FCs and similar man-made gases break down the ozone in the stratosphere allowing in harmful ultraviolet radiation. The ozone hole happens mostly in Antarctica where four months of winter darkness create ideal conditions for the destruction.