Pulse wave velocity (PWV) is a measure of arterial stiffness.he study of the basic scientific principles of the velocity of the pulse wave through the arterial tree dates back to 1808 with the work of Thomas Young.
Put simply, chain migration is a derogatory term used to describe the ability of U.S. citizens and green card holders to bring their extended family into the country. A majority of the roughly one million foreigners who are allowed to enter the U.S. to become permanent residents each year are approved because they're related to Americans.
Insect migration. Insect migration is the seasonal movement of insects, particularly those by species of dragonflies, beetles, butterflies and moths. The distance can vary with species and in most cases these movements involve large numbers of individuals. In some cases the individuals that migrate in one direction may not return and the next generation may instead migrate in the opposite direction. This is a significant difference from bird migration.