Science — page 109 of 132

13,110 terms including subtopics (0 terms filed directly here)

Science terms

Signals Internal and external factors that control changes in cell structure and function.
Significant hazard A downstream hazard classification for dams in which 1-6 lives are in jeopardy and appreciable economic loss (rural area with notable agriculture…
Significant Wave Height The average height of the one-third highest waves of a given wave group.
Significant Weather Outlook A narrative statement produced by the National Weather Service, frequently issued on a routine basis, to provide information regarding the potential of…
SIGWX Significant Weather
Silencer A device used for reducing noise within air and gas flow systems.
silencing Loss of gene expression either through an alteration in the of a structural gene, or its regulatory region; or because of interactions between its…
silent mutation See: mutation.
Silicic volcanism Volcanism characterized by the eruption of magma that is rich in lighter elements such as silicon, oxygen, aluminum, sodium, and potassium.
Silicon A chemical element, of atomic number 14, that is semi-metallic, and an excellent semiconductor material used in solar photovoltaic devices; commonly found…
Sill 1.The lower horizontal part of a window frame or window opening; also the accessory member which extends as a weather barrier from frame to outside face…
Silt A rock or mineral fragment of any composition that has a diameter ranging from 0.002 to 0.05 millimeter.
Silt (rock flour) The fine-grained portion of soil that is nonplastic or very slightly plastic and that exhibits little or no strength when air dry.
Siltation Process by which loose soil is transferred and builds up in streams, rivers, and lakes, causing changes in stream channels and in depth.
Silting Filling with soil or mud deposited by water.
Siltstone A sedimentary rock made mostly of silt-sized grains.
Silviculture The theory and practice of forest stand establishment and management.
Simple CS (Caulk and Seal) A technique for insulating and sealing exterior walls that reduces vapor diffusion through air leakage points by installing pre-cut blocks of rigid foam…
simple sequence repeat (Abbreviation: SSR). See: microsatellite.
Simulid Group of two-winged flying insects who live their larval stage underwater and emerge to fly about as adults.
Simultaneous Occurring at the same time.
SINE Without.
Sine Wave The type of alternative current generated by alternating current generators, rotary inverters, and solid-state inverters.
Single Cell Thunderstorm This type of thunderstorm develops in weak vertical wind shear environments. On a hodograph, this would appear as a closely grouped set of random dots…
single copy A gene or DNA sequence which occurs only once per (haploid ) genome. Many structural genes are single copy.
single domain antibody See: dAb.
Single Glaze or Pane One layer of glass in a window frame. It has very little insulating value (R-1) and provides only a thin barrier to the outside and can account for…
single node culture Culture of separate lateral bud s, each carrying a piece of stem tissue.
single nucleotide polymorphism (... NOO-klee-oh-TIDE PAH-lee-MOR-fih-zum) The most common type of change in DNA (molecules inside cells that carry genetic information).
Single nucleotide polymorphism (SNP) DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence is altered.
single nucleotide polymorphisms (SNPs) Common, but minute, variations that occur in human DNA at a frequency of one every 1,000 bases.
single primer amplification reaction (Abbreviation: SPAR). A PCR-based genotyping technique in which genomic template is amplified with a single primer.
Single settlement system A market structure that provides only a real-time market.
Single-cell cloned A procedure pertaining to cells in vitro in which the descendants of a single cell are physically isolated from other cells growing in a dish, and then…
single-cell line See: cell strain.
single-cell protein (Abbreviation: SCP). Protein produced by micro-organisms, particularly yeast. Used as either a feed or a food additive.
single-column modeling (SCM) (SCM) An approach to the development and testing of cloud formation and parameterizations.
Single-Crystal Material In reference to solar photovoltaic devices, a material that is composed of a single crystal or a few large crystals.
Single-gene disorder Hereditary disorder caused by a mutant allele of a single gene (e.g., Duchenne muscular dystrophy, retinoblastoma, sickle cell disease).
Single-Package System A year 'round heating and air conditioning system that has all the components completely encased in one unit outside the home.
Single-Phase A generator with a single armature coil, which may have many turns and the alternating current output consists of a succession of cycles.
Single-stage pump A pump that has only one impeller.
single-strand conformational polymorphism (Abbreviation: SSCP). A technique for detection of mutations in a defined DNA sequence.
single-strand DNA binding protein A protein that coats single-stranded DNA, preventing renaturation and so maintaining the DNA in an extended state.
single-stranded DNA (Abbreviation: ssDNA). DNA molecules separated from their complementary strand, either by its absence or following denaturation.
single-stranded nucleic acid Nucleic acid molecules consisting of only one polynucleotide chain. The genomes of many viruses are single-stranded DNA molecules, as are most…
Sink Any process, activity, or mechanism which removes a greenhouse gas, an aerosol, or a precursor of a greenhouse gas or aerosol from the atmosphere.
Sinkhole A steep-sided depression formed when removal of subsurface embankment or foundation material causes overlying material to collapse into the resulting void.
Sinuosity The ratio of the length of a river's thalweg to the length of the valley proper. A measure of a river's meandering. Rivers with a sinuosity less than 1.
Siphon A pipe connecting two canals. A tube or pipe through which water flows over a high point by gravity.
Siphon Spillway A spillway with one or more siphons built at crest level. This type of spillway is sometimes used for providing automatic surface-level regulation within…
Siphon tube Relatively short, light-weight, curved tube used to convey water over ditch banks to irrigate furrows or borders.
Siphonage A partial vacuum created by the flow of liquids in pipes.
SIRE Male animal chosen for breeding.
sister chromatid exchange (Abbreviation: SCE). Reciprocal interchanges of the two chromatid arms within a single chromosome.
Site In archeology, any location of past human activity.
Site Plan A drawing of the footprint of the subject building and immediate adjacent buildings indicating the location of the proposed work.
Site potential tree A tree that has attained the average maximum height possible given site conditions where it occurs.
Site preparation Various treatments applied to a harvested area to promote regeneration of the site.
Site Specific Hydrologic Prediction System (SSHP) (SSHP) The WFO hydrologic forecast model for small rivers and streams that uses RFC soil moisture state variables, stage and precipitation data.
Site-directed mutagenesis The process of introducing spe- cific base-pair mutations into a gene.
Site-Specific A term used to describe any process or enzyme which acts at a defined sequence within a DNA or RNA molecule.
site-specific mutagenesis The induction of mutation s, by molecular biology techniques, in one or more specific nucleotide s within a defined coding sequence in order to create…
SITOR (SImplex Teletype Over Radio) - a means of transmitting text broadcasts over radio. The U.S.
sitosterol See: phytosterol.
six-base cutter Type II restriction endonucleases whose recognition site and cleavage site consist of a characteristic sequence of six nucleotide pairs.
Sizing The process of designing a solar system to meet a specified load given the solar resource and the nominal or rated energy output of the solar energy…
Skewed Tilted images. See De-skewing.
Skidder A self-propelled machine to transport harvested trees or logs from the stump area to the landing or work deck.
Skimmer gate A gate at the spillway crest whose prime purpose is to control the release of debris and logs with a limited amount of water.
Skin biopsy Process of removing tissue, in this case skin, from living patients for diagnostic examination, or the tissue specimen obtained by that process.
SKIP A non-digging bucket or tray that hoists material
Skirt (fan, dune) A sloping alluvial fan surface made of sediment deposited by a stream at the mouth of a canyon between a mountain and the adjacent alluvial valley floor.
Skiving To dig in thin layers.
sky brightness temperature A descriptive measure of radiation in terms of the temperature of a hypothetical black body emitting an identical amount of radiation at the same…
Sky Condition Used in a forecast to describes the predominant/average sky condition based upon octants (eighths) of the sky covered by opaque (not transparent) clouds.
Sky glow Brightening of the sky caused by outdoor lighting and natural atmospheric and celestial factors.
Skylight A window located on the roof of a structure to provide interior building spaces with natural daylight, warmth, and ventilation.
Skylining Siting of a structure on or near a ridge line so that it is silhouetted against the sky.
SKYWARN A nationwide network of volunteer weather spotters who report to and are trained by the National Weather Service.
SL Sea Level
Slab A concrete pad that sits on gravel or crushed rock, well-compacted soil either level with the ground or above the ground.
Slab on Grade A slab floor that sits directly on top of the surrounding ground.
Slaking The process of breaking up or sloughing when an indurated soil is immersed in water.
Slash The unmerchantable material left on site subsequent to harvesting a timber stand, including tops, limbs, cull sections.
Slate Fine-grained metamorphic rock formed by "baking" and recrystallizing shale or mudstone and which splits easily along flat, parallel planes.
SLD Solid
Sleet Precipitation that consists of clear pellets of ice; sleet is formed when raindrops fall through a layer of cold air and freeze.
Sleet Warning Issued when accumulation of sleet in excess of 1/2" is expected; this is a relatively rare scenario.
SLGT Slight
Slide A small landslide.
Slide gate A steel gate that upon opening or closing slides on its bearings in edge guide slots. A gate that can be opened or closed by sliding in supporting guides.
Slide Gate (Sluice Gate) A gate that can be opened or closed by sliding it in supporting guides.
Slight Chance In probability of precipitation statements, usually equivalent to a 20 percent chance.
Slight Risk (of severe thunderstorms)- Severe thunderstorms are expected to affect between 2 and 5 percent of the area.
Sling Psychrometer An instrument used to measure the water vapor content of the atmosphere in which wet and dry bulb thermometers are mounted on a frame connected to a…
Slinky<sup>TM</sup> Ground Loop In this type of closed-loop, horizontal geothermal heat pump installation, the fluid-filled plastic heat exchanger pipes are coiled like a SlinkyTM to…
SLIP Motion occurring along a fault plane.
Slip rate The rate of motion obtained when the amount of offset is divided by a time interval.
SLO Slow