Science terms starting with E

619 terms

EWS - early warning system.
EWW Extreme Wind Warning (EWW) inform the public of the need to take immediate shelter in an interior portion of a well-built structure due to the onset of…
ex vitro Organisms removed from tissue culture and transplanted; generally plants to soil or potting mixture.
Ex vivo (ex VEE-voh) Outside of the living body. Refers to a medical procedure in which an organ, cells, or tissue are taken from a living body for a treatment or…
ex vivo gene therapy The delivery of a gene or genes to the isolated cells of an individual, with the intention of alleviating a genetic disorder.
ex-situ conservation The conservation of components of biological diversity outside their natural habitats.
Examination report A written report that documents the condition of the facility during the examination, operation and maintenance activities accomplished since the last…
Excavation The action or process of excavating (to dig or remove earth). See common excavation, rock excavation, and unclassified excavation.
Exceedance A measured level of an air pollutant that is higher than the national or state ambient air quality standards. See also NAAQS and CAAQS
Excess annual growth The amount by which new forest growth exceeds removal in a year. The annual quantity of wood produced in a forest in excess of market demand.
Excess capacity Power generation capacity available on a short-term basis that exceeds the firm energy on a long-term contract offered to an electricity customer.
Excess land Irrigable land, other than exempt land, owned by any landowner in excess of the maximum ownership entitlement under applicable provision of Reclamation…
Excess Rain Effective rainfall in excess of infiltration capacity.
Excessive grades Ground surface inclines relative to the horizon beyond which the ground may become unstable.
Excessive Heat Excessive heat occurs from a combination of high temperatures (significantly above normal) and high humidities.
Excessive Heat Outlook This CPC product, a combination of temperature and humidity over a certain number of days, is designed to provide an indication of areas of the country…
Excessive Heat Warning Issued within 12 hours of the onset of the following criteria: heat index of at least 105F for more than 3 hours per day for 2 consecutive days, or heat…
Excessive Heat Watch Issued by the National Weather Service when heat indices in excess of 105F (41C) during the day combined with nighttime low temperatures of 80F (27C) or…
Excessive slopes See Excessive grades
Exchange An exchange generally occurs when one company acquires another. The shareholders of the acquired company are often given the option to sell their shares…
Exchange capacity The capacity to exchange ions as measured by the quantity of exchangeable ions in a soil or rock.
excinuclease The endonuclease -containing protein complex that excises a segment of damaged DNA during excision repair.
excision (ek-SIH-zhun) Removal by surgery.
excision repair DNA repair processes that involve the removal of a damaged or incorrect segment of one strand of double-stranded DNA and its replacement by the synthesis of a…
Excitation The power required to energize the magnetic field of a generator.
excitation wavelength The specific wavelength of light required to stimulate a fluorescent molecule, such as a labelled probe, to emit light at the (lower) emission wavelength.
Excited state The state of an atom or nucleus when it possesses more than its normal energy. The excess energy is usually released eventually as a gamma ray.
EXCLD Exclude
Exclusive Economic Zone (EEZ) The assertion of jurisdiction under the EEZ (3 nautical miles/3.45 statute miles to 200 nautical miles/230.
Exclusive flood control capacity The reservoir capacity assigned to the sole purpose of regulating flood inflows to reduce flood damage downstream.
Exclusive Flood Control Storage Capacity The space in a reservoir reserved for the sole purpose of regulating flood inflows to abate flood damage.
excrete (ek-SKREET) To get rid of waste material from the blood, tissues, or organs by a normal discharge (such as sweat, urine, or stool).
Executive Order A president's or governor's declaration which has the force of law, usually based on existing statutory powers, and requiring no action by the Congress or…
Executive Orders Numbered consecutively, Executive Orders (EOs) are legally binding orders given by the President, acting as the head of the Executive Branch, to Federal…
Exempt land Irrigation land in a district to which the acreage limitation and pricing provisions of Reclamation law do not apply.
Exempt Wholesale Generator An unregulated subsidiary of a power provider that is allowed to generate and sell wholesale power as an independent energy producer, and is exempt from…
Existence value Value people place on simply knowing an area or feature continues to exist in a particular condition.
Existing ground The earth's surface as it is prior to any work. See original ground surface.
Exit channel. See outlet channel.
Exit conference A discussion following a facility review examination involving examination team members and interested representatives of the water uses, project, and…
Exit Region The region downstream from a wind speed maximum in a jet stream (jet max), in which air is moving away from the region of maximum winds, and therefore is…
exit site (Abbreviation: E site). The ribosome binding site that contains the free tRNA prior to its release.
exo III See: exonuclease III.
exocrine gland An animal gland that secretes through a duct.
exodeoxyribonuclease III See: exonuclease III.
exogamy See: outbreeding.
exogenous Produced outside of; originating from, or due to, external causes. Opposite: endogenous.
Exogenous DNA DNA that has been derived from one organism, and is to be introduced into a cell a different species. Also referred to as foreign DNA or heterologous DNA.
Exon A DNA sequence that is ultimately translated into protein. See DNA.
exon amplification A procedure that is used to amplify exons.
Exonuclease See Nuclease.
exonuclease III (Abbreviation: exo III). An Escherichia coli enzyme that removes nucleotides from the 3' hydroxyl ends of double-stranded DNA.
exopolysaccharide A polysaccharide that is secreted by a micro-organism into the surrounding environment.
Exosphere The upper most layer of the earth's atmosphere; the only layer where atmospheric gases can escape into outer space.
Exothermic A reaction or process that produces heat; a combustion reaction.
Exotic species A non-native species that is introduced into an area.
exotoxin A toxin released by a bacterium into the medium in which it grows.
Expanded Polystyrene A type of insulation that is molded or expanded to produce coarse, closed cells containing air.
Expansion The increase in volume of a soil mass.
Expansion joint A separation between adjoining parts of a concrete structure which is provided to allow small relative movements, such as those caused by temperature…
Expansion Tank A tank used in a closed-loop solar heating system that provides space for the expansion of the heat transfer fluid in the pressurized collector loop.
Expansion Valve The device that reduces the pressure of liquid refrigerant thereby cooling it before it enters the evaporator coil in a heat pump.
expected progeny difference (Abbreviation: EPD). The predicted performance of the future offspring of an individual for a particular trait, calculated from measurement(s) of the…
Experimental Product An experimental product is in the final stages of testing and evaluation. If the product proves accurate and valuable to users then the next step is to…
explant A portion of a plant aseptically excised and prepared for culture in a nutrient medium.
explant donor The plant from which an explant has been taken.
explantation The removal of cells, tissues or organs of animals and plants for observation of their growth and development in appropriate culture media.
Exploit Excavate in such a manner as to utilize material in a particular vein or layer, and waste or avoid surrounding material.
explosion method A technique for the genetic transformation of cells, in which the transgene is driven into the target (plant) cells by the sudden vaporization (effected…
Explosive Deepening A decrease in the minimum sea-level pressure of a tropical cyclone of 2.5 mb/hr for at least 12 hours or 5 mb/hr for at least six hours.
Exponential growth Growth in which some quantity, such as population size, increases by a constant percentage of the whole during each year or other time period; when the…
exponential phase See: logarithmic phase.
export Data extracted or taken out of one environment or application usually in a prescribed format, and usually for import into another environment or…
exposure Contact of an organism with a chemical, radiological, or physical agent.
exposure assessment The process by which contact with a toxic substance is identified and quantified.
Express To translate a gene's message into a molecular product.
Expressed gene See: gene expression
expressed sequence tag (Abbreviation: EST). Partially sequenced cDNA clone. Because the read length of a standard DNA sequencing reaction is shorter than the majority of cDNA…
Expressed sequence tag (EST) A short strand of DNA that is a part of a cDNA molecule and can act as identifier of a gene. Used in locating and mapping genes.
Expression library (See Library.)
expression system Combination of host and vector which provides a genetic context for making a cloned gene functional, i.e. produce peptide, in the host cell.
expression vector A cloning vector that has been constructed in such a way that, after insertion of a DNA molecule, its coding sequence is properly transcribed and the mRNA…
expressivity Degree of expression of a trait controlled by a particular gene. The gene may show different degrees of expression in different individuals.
EXTD Extend/Extended
Extended Forecast Discussion This discussion is issued once a day around 2 PM EST (3 PM EDT) and is primarily intended to provide insight into guidance forecasts for the 3- to 5-day…
extension The short single-stranded stretch of nucleotides remaining on a double-stranded DNA molecule, following treatment with a restriction endonuclease which…
Extensional (structural features or faults) Refers to tectonic forces that extend or stretch the Earth's crust.
External Combustion Engine An engine in which fuel is burned (or heat is applied) to the outside of a cylinder; a Stirling engine.
external data Data whose origin is not from within the ARM Program; may include data observed at ARM facilities, but whose processing and quality control is done by…
External Data Center (XDC) Stores data from non-ARM sources. It is managed by Brookhaven National Laboratory.
external guide sequence (Abbreviation: EGS). See: guide sequence.
external instruments Instruments that belong to organizations that are outside of the ARM Program.
Externality The environmental, social, and economic impacts of producing a good or service that are not directly reflected in the market price of the good or service.
Extirpated species A species which has become extinct in a given area.
Extirpation The elimination of a species or subspecies from a particular area, but not from its entire range.
Extracellular matrix The microenvironment next to a cell that allows for structural support, orientation, and connections for cell-to-cell interactions and formation of…
extrachromosomal In eukaryotes, non-nuclear DNA, present in cytoplasm organelles such as mitochondria and chloroplasts . In prokaryotes, non-chromosomal DNA, i.e. plasmids.
extrachromosomal inheritance See: cytoplasmic inheritance.
extractives Any number of different compounds in biomass that are not an integral part of the cellular structure.
Extrados The curved upstream surface of horizontal arch elements in an arch dam. See intrados.