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).
n (Geology) the movement of the earth's magnetic poles with respect to the geographic poles. English Collins Dictionary-English Definition & Thesaurus &nbsp. See also: polar axis, polar bear, polar body, polar circle. polar vortex. polar vortex. n. a large pocket of very cold air, typically the coldest air in the Northern Hemisphere, which sits over the polar region. tidal energy. tidal energy. n.