Introduction. Beta-blockers, also known as beta-adrenoceptor blocking agents, are medications used to treat conditions such as angina, heart failure and high blood pressure. They decrease the activity of the heart by blocking the action of hormones like adrenaline.
1 The concept of âdemographic changeâ describes a populationâs age structure adjusting to. changes in living conditions. Consequently, changes in thcomposition of a societyâe s age. structure are the result of social shifts. (. 2  cf. . 3  theory of first and second demographic transition.
POPULATION GROWTH. One of the primary purposes of the U.S. Census is to measure population distribution and change. Although the nation as a whole has continued to expand, growth has been far from uniform. Between 1990 and 2000, 684 of the nation's 3142 counties reported a population loss, many of these in the Great Plains states.