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 world population growth is approximately 1.09%. The world population more than tripled during the 20th century from about 1.65 billion in 1900 to 5.97 billion in 1999. It reached the 2 billion mark in 1927, the 3 billion mark in 1960, 4 billion in 1974, and 5 billion in 1987. Currently, population growth is fastest among low wealth, Third World countries.