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  2. Population density - Wikipedia

    en.wikipedia.org/wiki/Population_density

    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 ...

  3. Mulliken population analysis - Wikipedia

    en.wikipedia.org/wiki/Mulliken_population_analysis

    The sum of the gross orbital products is N - the total number of electrons. The Mulliken population assigns an electronic charge to a given atom A, known as the gross atom population: as the sum of over all orbitals belonging to atom A. The charge, , is then defined as the difference between the number of electrons on the isolated free atom ...

  4. Density matrix - Wikipedia

    en.wikipedia.org/wiki/Density_matrix

    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 ...

  5. Urban density - Wikipedia

    en.wikipedia.org/wiki/Urban_density

    Urban density is a term used in urban planning and urban design to refer to the number of people inhabiting a given urbanized area. As such it is to be distinguished from other measures of population density. Urban density is considered an important factor in understanding how cities function. Research related to urban density occurs across ...

  6. Population dynamics - Wikipedia

    en.wikipedia.org/wiki/Population_dynamics

    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 mathematical biology has greatly expanded. [citation needed] The beginning of population dynamics is widely regarded as the work of Malthus, formulated as the ...

  7. Number density - Wikipedia

    en.wikipedia.org/wiki/Number_density

    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.

  8. Friedmann equations - Wikipedia

    en.wikipedia.org/wiki/Friedmann_equations

    The density parameter Ω is defined as the ratio of the actual (or observed) density ρ to the critical density ρ c of the Friedmann universe. The relation between the actual density and the critical density determines the overall geometry of the universe; when they are equal, the geometry of the universe is flat (Euclidean).

  9. Voronoi diagram - Wikipedia

    en.wikipedia.org/wiki/Voronoi_diagram

    The simplest case. In the simplest case, shown in the first picture, we are given a finite set of points {, …} in the Euclidean plane.In this case each site is one of these given points, and its corresponding Voronoi cell consists of every point in the Euclidean plane for which is the nearest site: the distance to is less than or equal to the minimum distance to any other site .