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.
This is the period in history when population growth changed most drastically. Before 1800 the world population growth rate was always well below 1%, while in the course of the first fifty years of the 20th century annual growth increase to up to 2.1% â the highest annual growth rate in history, recorded in 1962.