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.
The United States is estimated to have a population of 323,127,513 as of July 1, 2016, making it the third most populous country in the world. It is very urbanized, with 81% residing in cities and suburbs as of 2014 (the worldwide urban rate is 54%). California and Texas are the most populous states, as the mean center of U.S. population has consistently shifted westward and southward. New York City is the most populous city in the United States. The total fertility rate in the United States estimated for 2016 is 1.82 children per woman, which is below the replacement fertility rate of approximately 2.1.