Age Structure


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Age Structure

A characteristic of a population which reflects its historical trends in birth and death rates. Until the 20th century, the human age structure had remained relatively constant and had a pyramidal appearance with a relatively large number of children at the base and, due to a higher average mortality in the 30–50+ group/1000, a narrow apex of persons who made it to old age. With the improving health and decline in both infant mortality and birth rate, the age structure is undergoing a transition, to an increasingly columnar form, especially as developing nations achieve a balanced rate of reproduction.
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In this study we use herb-chronology, the aging of herbaceous individuals by counting annual growth rings in their perennial woody belowground taproot, to evaluate if mowing frequency influences population age structure, number of stems by age class, and number of flowering stems by age class.
Hence, there are some countries that need to increase their population, while others on contrary need to decrease their population depending on the age structure, as some will need more younger people in order to work in the labour force and increase the country's productivity.
Evaluation of using random-at-length observations and an equilibrium approximation of the population age structure in fitting the von Bertalanffy growth function.
After early studies found that the size distribution and age structure of the population were unique, managers in 1986 imposed a 4-fish bag limit, with only one over 27 inches.
Long gun seasons throughout the rut, liberal buck bag limits and liberal antlerless tags all make for shrinking herds and very poor buck age structure in Virginia.
This edition concerns itself with the various aspects of global demographic change and its importance for the production of technical textiles and its associated industries, looking at the age structure of the population, the quantitative relationship between men and women, the birth and mortality rates, etc., and its implications for the technical textiles producers and their partner sectors.
From October 2013 to April 2014, the age structure of the Tundra Swan was surveyed by point count method at 45 survey sites of Poyang Lake.
The concept of "demographic change" refers to a population's age structure adjusting to changes in living situations (Linz and Stula, 2010).
The particular challenge now is that while most rich countries had decades to adjust to this change in age structure, many less developed countries are seeing these changes happen within a single generation.
According to James (2008), this phenomenon occurs with a falling birth rate and the consequent shift in the age structure of the population towards the adult working age.
The value of Ex (average survival probability among larval stages on successive metamorphosis) was calculated by formula Lx-(1/2(dx)), representing the age structure. Tx was estimated by the formula [SIGMA] Ex+(Ex+1)+Ew, where "w" is the maximum larval stage in weeks; life expectancy will be estimated by Tx/Lx.
Asif Wazir said the opportunity depends on many important decisions that have to be taken immediately to determine whether the changes in age structure contribute to a dividend or a disaster.

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