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Exponential decay is a process where a quantity decreases at a rate proportional to its current value. Learn the differential equation, the decay constant, the mean lifetime, the half-life, and the applications of exponential decay in physics, chemistry, biology, and more.
Half-life is the time required for a quantity to reduce to half of its initial value. Learn how to calculate half-life for different types of exponential decay, such as radioactive decay, chemical reactions and population growth, with formulas and examples.
The time constant, denoted by τ, is a parameter that characterizes the response of a first-order, linear time-invariant system to a step input. Learn how to calculate the time constant, its relation to the bandwidth, and its applications in physics, engineering and radioactive decay.
The plateau principle is a model that describes the time course of change in a system with constant input and output. It applies to drug action, nutrition, biochemistry, and system dynamics. Learn the equations, examples, and applications of the plateau principle.
Lutetium–hafnium dating is a geochronological dating method utilizing the radioactive decay system of lutetium–176 to hafnium–176. [1] With a commonly accepted half-life of 37.1 billion years, [1] [2] the long-living Lu–Hf decay pair survives through geological time scales, thus is useful in geological studies. [1]
In phenomenological applications, it is often not clear whether the stretched exponential function should be used to describe the differential or the integral distribution function—or neither. In each case, one gets the same asymptotic decay, but a different power law prefactor, which makes fits more ambiguous than for simple exponentials.
Clearance is a pharmacokinetic parameter that measures the efficiency of drug elimination from the body. It is the rate of elimination of a substance divided by its concentration, and it depends on various factors such as plasma protein binding, renal function, and dialysis.
Alternatively, since the radioactive decay contributes to the "physical (i.e. radioactive)" half-life, while the metabolic elimination processes determines the "biological" half-life of the radionuclide, the two act as parallel paths for elimination of the radioactivity, the effective half-life could also be represented by the formula: [1] [2]