Attenuation
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Attenuation is the decrease of the amount, force, magnitude, or value of something.
- In biology, attenuation is a mechanism in the regulation of gene expression
- In ecology and geochemistry, attenuation is the ability to withhold contaminants in soil and groundwater by various mechanisms like adsorption, dilution, dispersion or biological degradation (biodegradation, bioremediation), causing a decrease in concentration and toxicity compared to the total amount of the contaminant. In environmental engineering and remediation this is often called natural attenuation[1] (http://toxics.usgs.gov/definitions/natural_attenuation.html).
- In physical oceanography, light attenuation is the decrease in light intensity with depth in the water column due to absorption (by water molecules) and scattering (by suspended particulates).
- In telecommunication, attenuation is the decrease in intensity of a signal, beam, or wave as a result of absorption of energy and of scattering out of the path to the detector, but not including the reduction due to geometric spreading.
- In statistics, attenuation is another term for regression dilution.
- Note 1: Attenuation is usually expressed in dB.
- Note 2: "Attenuation" is often used as a misnomer for "attenuation coefficient, " which is expressed in dB per kilometer.
- Note 3: A distinction must be made as to whether the attenuation is that of signal power or signal electric field strength.
- Source: from Federal Standard 1037C and adapted from the Department of Defense Dictionary of Military and Associated Terms