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  2. Clarke number - Wikipedia

    en.wikipedia.org/wiki/Clarke_number

    Clarke number or clarke is the relative abundance of a chemical element, typically in Earth's crust. The technical definition of "Earth's crust" varies among authors, and the actual numbers also vary significantly.

  3. CRC Standard Mathematical Tables - Wikipedia

    en.wikipedia.org/wiki/CRC_Standard_Mathematical...

    The 30th edition (1996) was renamed CRC Standard Mathematical Tables and Formulae, with Daniel Ian Zwillinger as the editor-in-chief. [2] The 33rd edition (2018) was renamed CRC Standard Mathematical Tables and Formulas. [3]

  4. Relative species abundance - Wikipedia

    en.wikipedia.org/wiki/Relative_species_abundance

    Relative species abundance is a component of biodiversity and is a measure of how common or rare a species is relative to other species in a defined location or community. [1] Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in the area.

  5. δ15N - Wikipedia

    en.wikipedia.org/wiki/Δ15N

    The difference is whether the relative abundance is with respect to all the nitrogen, i.e. 14 N plus 15 N, or just to 14 N. Since the atmosphere is 99.6337% 14 N and 0.3663% 15 N, a is 0.003663 in the former case and 0.003663/0.996337 = 0.003676 in the latter.

  6. Abundance (ecology) - Wikipedia

    en.wikipedia.org/wiki/Abundance_(ecology)

    In ecology, local abundance is the relative representation of a species in a particular ecosystem. [1] It is usually measured as the number of individuals found per sample . The ratio of abundance of one species to one or multiple other species living in an ecosystem is referred to as relative species abundances . [ 1 ]

  7. Colossally abundant number - Wikipedia

    en.wikipedia.org/wiki/Colossally_abundant_number

    Colossally abundant numbers were first studied by Ramanujan and his findings were intended to be included in his 1915 paper on highly composite numbers. [2] Unfortunately, the publisher of the journal to which Ramanujan submitted his work, the London Mathematical Society, was in financial difficulties at the time and Ramanujan agreed to remove aspects of the work to reduce the cost of printing ...

  8. Atomic ratio - Wikipedia

    en.wikipedia.org/wiki/Atomic_ratio

    Another application is in radiochemistry, where this may refer to isotopic ratios or isotopic abundances.Mathematically, the isotopic abundance is = , where N i are the number of atoms of the isotope of interest and N tot is the total number of atoms, while the atomic ratio is

  9. Saprobic system - Wikipedia

    en.wikipedia.org/wiki/Saprobic_system

    The saprobic system is based on a survey of indicator organisms. For example, the abundance of Lymnaea stagnalis water snails and other organisms is estimated, and using a formula, the listed saprobic and tolerance values of the organisms allow the water quality grade — the saprobic index — to be computed.