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.
Source for Population: 2010 Demographic Profile -- U.S. Census Bureau. Source for Population Density: Population 19 -- U.S. Census Bureau, Statistical Abstract of the United States: 2012 -- Table 14. State PopulationâRank, Percent Change, and Population Density: 1980 to 2010. Source for Size, Land Area, and Water Area: United States -- States; and Puerto Rico - GCT-PH1.