Science — page 17 of 132

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

Subtopics

Science terms

  1. Brayton Cycle A thermodynamic cycle using constant pressure, heat addition and rejection, representing the idealized behavior of the working fluid in a gas turbine type…
  2. BRC - Budget Review Committee, Bureau Procurement Chief.
  3. BRCA1/BRCA2 The first breast cancer genes to be identified. Mutated forms of these genes are believed to be responsible for about half the cases of inherited breast…
  4. BRD Blackrock Depths
  5. Breach 1. The breaking or violating of a law, right or duty, either by an act or omission. 2. The failure to carry out any condition of a contract.
  6. Breach hydrograph A flood hydrograph resulting from a dam breach.
  7. Bread Box System This simple passive solar hot water system consists of one or more storage tanks placed in an insulated box that has a glazed side facing the sun.
  8. Breakers Waves that break, displaying white water. Depends on wave steepness and bottom bathymetry.
  9. Breakup The time when a river whose surface has been frozen from bank to bank for a significant portion of its length begins to change to an open water flow…
  10. Breakup Date Date on which a body of water is first observed to be entirely clear of ice and remains clear thereafter.
  11. Breakup Jam Ice jam that occurs as a result of the accumulation of broken ice pieces.
  12. Breakup Period The period of disintegration of an ice cover.
  13. Breccia A sedimentary rock formed of coarse-grained material consisting of sharp fragments embedded in clay or sand.
  14. Breccia (volcanic breccia) Conglomerate-like rock made up of angular pieces of volcanic rock usually bound in volcanic ash.
  15. Brecciated A rock made up of highly angular, coarse fragments.
  16. breed 1.a sub-specific group of domestic livestock with definable and identifiable external characteristics that enable it to be separated by visual appraisal…
  17. breed at risk An animal breed that is in danger of becoming extinct because its population has fallen below a critical number.
  18. breeding The process of sexual reproduction and production of offspring.
  19. Breeding density Density of sexually mature organisms in a given area during the breeding period.
  20. Breeding potential Maximum rate of increase in numbers of individuals of a species or population under optimum conditions.
  21. Breeding rate Actual rate of increase of new individuals in a given population; the breeding potential minus limiting factors.
  22. breeding value A quantitative genetics term, describing that part of the deviation of an individual phenotype from the population mean that is due to the additive…
  23. Breezy 15 to 25 mph winds
  24. brewer's yeast Strains of the yeast Saccharomyces cerevisiae that are used for the production of beer.
  25. BRF Brief
  26. bridge A filter paper or other substrate used as a wick and support structure for a plant tissue in culture when a liquid medium is used.
  27. Bridge, Class A A bridge located on a Federal-aid highway. Examination of this type of bridge is required every 2 years with an in-depth examination every 6 years.
  28. Bridge, Class B A bridge not located on a Federal-aid highway that is used by the public. Examination of this type of bridge is required every 3 years.
  29. Bridge, Class C A bridge not located on a Federal-aid highway that can be designated as being a private or operating bridge and could be gated or closed to the public, if…
  30. Bright Band The enhanced radar echo of snow as it melts to rain.
  31. Bright Surge on the Disk (BSD) In solar-terrestrial terms, a bright gaseous stream (surge) emanating from the chromosphere.
  32. Bright Surge on the Limb (BSL) In solar-terrestrial terms, a large gaseous stream (surge) that moves outward more than 0.15 solar radius above the limb.
  33. Brightness A basic visual sensation describing the amount of light that appears to emanate from an object, or more precisely, the luminance of an object
  34. Brine Water saturated or strongly impregnated with salt.
  35. Brisk 15 to 25 mph winds
  36. Brisk Wind Advisory A Small Craft Advisory issued by the National Weather Service for ice-covered waters.
  37. British thermal unit The quantity of heat required to raise the temperature of one pound of water one degree of Fahrenheit at or near 39.2 degrees Fahrenheit.
  38. British thermal unit (Btu) (BTU) The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit; equal to 252 calories.
  39. British thermal units (Btu) Quantity of heat required to raise the temperature of one avoirdupois pound of water 1 degree F at or near 39.2 degrees F.
  40. BRK Break
  41. BRM business reference model - an organized, hierarchical way to describe the day-to-day business operations of the Federal government; this model presents…
  42. BRN (Bulk Richardson Number) A non-dimensional number relating vertical stability and vertical shear (generally, stability divided by shear).
  43. Broad-crested weir An overflow structure on which the nappe is supported for an appreciable length in the direction of flow. See weir.
  44. broad-host-range plasmid A plasmid that can replicate in a number of different bacterial species.
  45. broad-sense heritability The proportion of the total phenotypic variation which results from genetic variation or interaction between the genotype and the environment.
  46. Broadband Communications of high capacity and usually of multimedia content.
  47. Broadband noise Noise that has a continuous spectrum, that is, energy is present over a wide range of frequencies.
  48. Broadcast burn Controlled fire over the entire surface of a designated area.
  49. Brocken Specter An optical phenomenon sometimes occurring at high altitudes when the image of an observer placed between the sun and a cloud is projected on the cloud as…
  50. Broken Level A layer of the atmosphere with 5/8 to 7/8 sky cover (cloud cover).
  51. Broker An agent who handles the public's orders to buy and sell securities, commodities or other property. A commission is generally charged for this service.
  52. broodstock The group of males and females from which fish are bred.
  53. Brownfields Sites that are underutilized or not in active use, on land that is either contaminated or perceived as contaminated.
  54. browning Discolouration of freshly cut surfaces of plant tissue due to phenolic oxidation.
  55. Brownout The partial reduction of electrical voltages. A brownout results in lights dimming and motor-driven devices slowing down. See blackout.
  56. Browse Twigs, leaves, and young shoots of trees and shrubs that animals eat.
  57. Bryophytes Plants of the phylum Bryophyta, including mosses, liverworts and hornworts, characterized by the lack of true roots, stems and leaves.
  58. Bryozoan Aquatic colonial animals with branching, mossy or fan-like growth. They resemble corals but have more complex nervous, muscular, and digestive systems.
  59. BS Blowing Snow
  60. BSA Abbreviation for bovine serum albumin.
  61. BSC base safety condition.
  62. BSE Abbreviation for bovine spongiform encephalopathy. See protein aceous infectious particle.
  63. BSO Business Services Office.
  64. BST Abbreviation for bovine somatotrophin.
  65. Bt See Bacillus thuringiensis.
  66. Bt corn A corn plant that has been developed though biotechnology so that the plant tissues express a protein derived from a bacterium, Bacillus thuringiensis…
  67. BTR Better
  68. BTU - British Thermal Units.
  69. BTWN Between
  70. bubble column fermenter A bioreactor in which the cells or micro-organisms are kept suspended in a tall cylinder by rising air, which is introduced at the base of the vessel.
  71. Bubble High A mesoscale area of high pressure, typically associated with cooler air from the rainy downdraft area of a thunderstorm or a complex of thunderstorms.
  72. Bubbler Gage A water stage recording device that is capable of attaching to a LARC for data automation purposes.
  73. Buck To cut a log into smaller portions.
  74. bucket A part of an excavator which digs, lifts, and carries dirt.
  75. bud A region of meristematic tissue with the potential for developing into leaves, shoots, flowers or combinations of these; generally protected by modified…
  76. bud sport A somatic mutation arising in a bud, generating a genetically different shoot. Includes changes due to gene mutation, chromosomal mutation or polyploidy.
  77. budding 1. A method of asexual reproduction in which a new individual is derived from an outgrowth (bud) that becomes detached from the body of the parent. 2.
  78. Budget Review Committee (BRC) An ad hoc committee of representatives from each Region, the Reclamation Service Center, and the Washington Office, coordinates Reclamation budget…
  79. BUDS business utilization development specialist.
  80. Buffer strips (filter strips, vegetated filter strips, grassed buffers) Strips of grass or other close-growing vegetation that separates a waterway (ditch, stream, creek) from an intensive land use area (subdivision, farm).
  81. Buffer Zone A strip of land created to separate and protect one type of land use from another; for example, as a screen of planting or fencing to insulate the…
  82. BUFKIT A software tool used by forecasters to examine the vertical profile and other aspects of the atmosphere.
  83. Build out The estimated extent of residential, commercial, and industrial development in a given geographic area; usually related to the upper limit of the…
  84. Build-out capacity The maximum total percentage of development in a watershed; typically determined assuming current zoning holds indefinitely into the future.
  85. Building Energy Ratio The space-conditioning load of a building.
  86. Building Envelope The structural elements (walls, roof, floor, foundation) of a building that encloses conditioned space; the building shell.
  87. Building Heat-Loss Factor A measure of the heating requirements of a building expressed in Btu per degree-day.
  88. Building Orientation The relationship of a building to true south, as specified by the direction of its longest axis.
  89. Building Overall Energy Loss Coefficient-Area Product The factor, when multiplied by the monthly degree-days, that yields the monthly space heating load.
  90. Building Overall Heat Loss Rate The overall rate of heat loss from a building by means of transmission plus infiltration, expressed in Btu per hour, per degree temperature difference…
  91. Built Environment The urban environment consisting of buildings, roads, fixtures, parks, and all other improvements that form the physical character of a city.
  92. Bulb The transparent or opaque sphere in an electric light that the electric light transmits through.
  93. Bulb Turbine A type of hydro turbine in which the entire generator is mounted inside the water passageway as an integral unit with the turbine.
  94. Bulk Density The weight of a material per unit of volume compared to the weight of the same volume of water.
  95. Bulk Richardson Number A non-dimensional (i.e., no units) number relating vertical stability to vertical shear (generally, stability divided by shear).
  96. bulked segregant analysis A method to obtain markers linked to a target trait, in which DNA samples, prepared from a number of individuals of each of two contrasting phenotypes…
  97. Bulkhead The part of a storefront that forms a base for one or more display windows
  98. Bulkhead Gate A gate used either for temporary closure of a channel or conduit before dewatering it for inspection or maintenance or for closure against flowing water…
  99. Bulking The increase in volume of a material due to manipulation. Rock bulks upon being excavated; damp sand bulks if loosely deposited, as by dumping, because…
  100. Bunchgrass A grass having a bunched growth form and lacking rhizomes.