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.
World Population: 1950-2050. The world population increased from 3 billion in 1959 to 6 billion by 1999, a doubling that occurred over 40 years. The Census Bureau's latest projections imply that population growth will continue into the 21st century, although more slowly. The world population is projected to grow from 6 billion in 1999 to 9 billion by 2044, an increase of 50 percent that is expected to require 45 years.