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Growth charts can also be compiled with a portion of the population deemed to have been raised in more or less ideal environments, such as nutrition that conforms to pediatric guidelines, and no maternal smoking. Charts from these sources end up with slightly taller but thinner averages. [1] Growth curve of a girl, compared to the 2006 WHO curves
Linear growth is a complex process regulated by the growth hormone (GH) – insulin-like growth factor-1 axis, the thyroxine/triiodothyronine axis, androgens, estrogens, vitamin D, glucocorticoids and possibly leptin. [25] GH is secreted by the anterior pituitary gland in response to hypothalamic, pituitary and circulating factors.
The formula can be read as follows: the rate of change in the population (dN/dt) is equal to growth (rN) that is limited by carrying capacity (1 − N/K). From these basic mathematical principles the discipline of population ecology expands into a field of investigation that queries the demographics of real populations and tests these results ...
In the study of age-structured population growth, probably one of the most important equations is the Euler–Lotka equation.Based on the age demographic of females in the population and female births (since in many cases it is the females that are more limited in the ability to reproduce), this equation allows for an estimation of how a population is growing.
For example, in microbiology, a population of cells undergoing exponential growth by mitosis replaces each cell by two daughter cells, so that = and is the population doubling time. If the population grows with exponential growth rate r {\displaystyle \textstyle r} , so the population size at time t {\displaystyle t} is given by
A study of a population of French women from 1670 and 1789 shows that those who married at age 20–24 had 7.0 children on average and 3.7% remained childless. Women who married at age 25–29 years had a mean of 5.7 children and 5.0% remained childless. Women who married at 30–34 years had a mean of 4.0 children and 8.2% remained childless. [20]
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F(X) is the instantaneous proliferation rate of the cellular population, whose decreasing nature is due to the competition for the nutrients due to the increase of the cellular population, similarly to the logistic growth rate. However, there is a fundamental difference: in the logistic case the proliferation rate for small cellular population ...