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  2. Biological half-life - Wikipedia

    en.wikipedia.org/wiki/Biological_half-life

    where k is the reaction rate constant. Such a decay rate arises from a first-order reaction where the rate of elimination is proportional to the amount of the substance: [39] =. The half-life for this process is [39] = ⁡.

  3. Half-life - Wikipedia

    en.wikipedia.org/wiki/Half-life

    Note the consequence of the law of large numbers: with more atoms, the overall decay is more regular and more predictable. A half-life often describes the decay of discrete entities, such as radioactive atoms. In that case, it does not work to use the definition that states "half-life is the time required for exactly half of the entities to decay".

  4. Radioactive decay - Wikipedia

    en.wikipedia.org/wiki/Radioactive_decay

    Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay.

  5. Corpse decomposition - Wikipedia

    en.wikipedia.org/wiki/Corpse_decomposition

    A fresh pig carcass. At this stage the remains are usually intact and free of insects. The corpse progresses through algor mortis (a reduction in body temperature until ambient temperature is reached), rigor mortis (the temporary stiffening of the limbs due to chemical changes in the muscles), and livor mortis (pooling of the blood on the side of the body that is closest to the ground).

  6. Exponential decay - Wikipedia

    en.wikipedia.org/wiki/Exponential_decay

    A quantity is subject to exponential decay if it decreases at a rate proportional to its current value. Symbolically, this process can be expressed by the following differential equation , where N is the quantity and λ ( lambda ) is a positive rate called the exponential decay constant , disintegration constant , [ 1 ] rate constant , [ 2 ] or ...

  7. Decomposition - Wikipedia

    en.wikipedia.org/wiki/Decomposition

    Decomposition rates are low under very wet or very dry conditions. Decomposition rates are highest in damp, moist conditions with adequate levels of oxygen. Wet soils tend to become deficient in oxygen (this is especially true in wetlands), which slows microbial growth. In dry soils, decomposition slows as well, but bacteria continue to grow ...

  8. Specific activity - Wikipedia

    en.wikipedia.org/wiki/Specific_activity

    One gram of rubidium-87 and a radioactivity count rate that, after taking solid angle effects into account, is consistent with a decay rate of 3200 decays per second corresponds to a specific activity of 3.2 × 10 6 Bq/kg. Rubidium atomic mass is 87 g/mol, so one gram is 1/87 of a mole. Plugging in the numbers:

  9. Potassium-40 - Wikipedia

    en.wikipedia.org/wiki/Potassium-40

    However, if the mineral contains traces of potassium, then decay of the 40 K isotope present will create fresh argon-40 that will remain locked up in the mineral. Since the rate at which this conversion occurs is known, it is possible to determine the elapsed time since the mineral formed by measuring the ratio of 40 K and 40 Ar atoms contained ...