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Population density is the number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county, city, country, another territory or the entire world . The world's population is around 8,000,000,000 [3 ...
Number density. The number density (symbol: n or ρN) is an intensive quantity used to describe the degree of concentration of countable objects ( particles, molecules, phonons, cells, galaxies, etc.) in physical space: three-dimensional volumetric number density, two-dimensional areal number density, or one-dimensional linear number density.
Ricker model. The Ricker model, named after Bill Ricker, is a classic discrete population model which gives the expected number N t+1 (or density) of individuals in generation t + 1 as a function of the number of individuals in the previous generation, [1] Here r is interpreted as an intrinsic growth rate and k as the carrying capacity of the ...
Population balance equation. Population balance equations (PBEs) have been introduced in several branches of modern science, mainly in Chemical Engineering, [1] to describe the evolution of a population of particles. This includes topics like crystallization, [2] leaching (metallurgy), [3] [4] liquid–liquid extraction, gas-liquid dispersions ...
Population dynamics is the type of mathematics used to model and study the size and age composition of populations as dynamical systems. History [ edit ] Population dynamics has traditionally been the dominant branch of mathematical biology , which has a history of more than 220 years, [1] although over the last century the scope of ...
In quantum mechanics, a density matrix (or density operator) is a matrix that describes the quantum state of a physical system. It allows for the calculation of the probabilities of the outcomes of any measurement performed upon this system, using the Born rule. It is a generalization of the more usual state vectors or wavefunctions: while ...
The force of mortality μ ( x) uniquely defines a probability density function fX ( x ). The force of mortality can be interpreted as the conditional density of failure at age x, while f ( x) is the unconditional density of failure at age x. [1] The unconditional density of failure at age x is the product of the probability of survival to age x ...
v. t. e. In probability theory, the expected value (also called expectation, expectancy, expectation operator, mathematical expectation, mean, expectation value, or first moment) is a generalization of the weighted average. Informally, the expected value is the arithmetic mean of the possible values a random variable can take, weighted by the ...