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 population of the US is a little over 300 million and the current population growth rate is a little under 1% per year which means that the population of the US is increasing by about 3 million people per year.he U.S. population constitutes only 5% of world population, but consumes 24% of world's energy. The U.S. is losing 400,000 acres of rural land per year, while urbanized land area increased between 1969 and 1990 at twice the rate of population growth in the same time period.