Science terms starting with D

722 terms

  1. Declining Block Rate An electricity supplier rate structure in which the per unit price of electricity decreases as the amount of energy increases.
  2. Decommissioning The process of removing a power plant, apparatus, equipment, building, or facility from operation.
  3. Decomposition The process of breaking down organic material; reduction of the net energy level and change in physical and chemical composition of organic material.
  4. Decontamination The removal of radioactive contaminants by cleaning and washing with chemicals.
  5. Decoupling A regulatory design that breaks the link between utility revenues and energy sales to encourage utility investment in conservation.
  6. Deed covenant A term used in association with the sale of excess lands. In order for an eligible buyer of excess land to receive Reclamation irrigation water on such…
  7. Deed Restriction A legally binding restriction on the use, activity, and/or limitation of property rights, recorded at the registry of deeds.
  8. Deep Discharge Discharging a battery to 20 percent or less of its full charge capacity.
  9. Deep percolation The movement of water by gravity downward through the soil profile beyond the root zone; this water is not used by plants.
  10. Deep Percolation Loss Water that percolates downward through the soil beyond the reach of plant roots.
  11. Deep Seepage Infiltration which reaches the water table.
  12. Deep well A well whose pumping head is too great to permit use of a suction pump.
  13. Deep-cycle battery A battery with large plates that can withstand many discharges to a low state of charge.
  14. Deepening A decrease in the central pressure of a surface low pressure system. The storm is intensifying.
  15. deepwater an ocean water mass with relatively uniform temperature, salinity, and density, found near the bottom of the ocean.
  16. defective virus A virus that, by itself, is unable to reproduce when infecting its host cell, but that can grow in the presence of another virus.
  17. deficiency (dih-FIH-shun-see) In medicine, a shortage of a substance (such as a vitamin or mineral) needed by the body.
  18. Deficiency Verification Analysis (DVA) This analysis verifies the existence or non-existence of Safety of Dams (SOD) deficiencies at the dam.
  19. defined 1. Fixed conditions of medium, environment and protocol for growth. 2. Precisely known and stated elements of a tissue culture medium.
  20. Deflagration To burn with sudden and startling combustion. Describes explosion of black powder, as opposed to the more rapid detonation of dynamite.
  21. Deflation A condition of decreasing prices. Deflation is generally measured by the Consumer Price Index.
  22. Deflect A decrease in the vertical diameter of a flexible pipe.
  23. Deflection Upstream or downstream movement of a dam or dike.
  24. Deforestation Those practices or processes that result in the conversion of forested lands for non-forest uses.
  25. Deformation Change in shape or size.
  26. Deformation Zone The change in shape of a fluid mass by variations in wind, specifically by stretching and/or shearing.
  27. Deformed Ice A general term for ice which has been squeezed together and forced upwards and downwards in places.
  28. degeneracy The specification of one amino acid by more than one codon. It arises from the inevitable redundancy resulting from the 64 possible codons encoding only…
  29. degeneration 1. Changes in cells, tissues or organs due to disease. 2. The reduction in size or complete loss of organs during evolution.
  30. Degradable See biodegradable.
  31. Degradation Process wherein the elevation of streambeds, sandbars, and flood plains is lowered by erosion. The opposite of aggradation.
  32. Degree Day A unit for measuring the extent that the outdoor daily average temperature (the mean of the maximum and minimum daily dry-bulb temperatures) falls below…
  33. Degree Hour The product of 1 hour, and usually the number of degrees Fahrenheit the hourly mean temperature is above a base point (usually 65 degrees Fahrenheit)…
  34. dehalogenation The removal of halogen atoms (fluorine, chlorine, bromine, iodine) from molecules, for example during biodegradation.
  35. dehiscence The spontaneous and often violent opening of a fruit, seed pod or anther to release and disperse the seeds or pollen.
  36. Dehumidifier A device that cools air by removing moisture from it.
  37. dehydration A condition caused by the loss of too much water from the body. Severe diarrhea or vomiting can cause dehydration.
  38. dehydrogenase An enzyme that catalyses the removal of hydrogen atoms in biological reactions.
  39. dehydrogenation A chemical reaction in which hydrogen is removed from a compound.
  40. dekatherm or decatherm (DTH) Ten therms, same as one million British thermal units or one MMBtu.
  41. Delay A device used to obtain detonation of charges at separate times. An electric blasting cap which explodes at a set interval after current is passed through…
  42. Delay pattern Order of firing charges obtained by arranging delays to fire separate holes or series of holes at different times.
  43. Deletion Deletion is the process whereby data is removed from active files and other data storage structures on computers and rendered inaccessible except using…
  44. Deletion map A description of a specific chromosome that uses defined mutations --specific deleted areas in the genome-- as 'biochemical signposts,' or markers for…
  45. deliberate release In a biotechnology context, the intentional release of genetically modified organisms.
  46. Delivery The amount of water delivered to the point of use. The difference between delivery and release is usually the same as consumptive use.
  47. Delivery Point(s) An industry-designated location at which delivery may be made in fulfillment of contract terms.
  48. Delta The relationship between an option's price and the price of the underlying stock or futures contract is called its delta.
  49. delta endotoxins See: cry proteins.
  50. Delta T Change in temperature. 1) A simple representation of the mean lapse rate within a layer of the atmosphere, obtained by calculating the difference between…
  51. Demand Form PCT/IPEA/401, filed with an International Preliminary Examining Authority, demanding that an international application shall be the subject of an…
  52. Demand (Tankless) Water Heater A type of water heater that has no storage tank thus eliminating storage tank stand-by losses.
  53. Demand Charge A charge for the maximum rate at which energy is used during peak hours of a billing period.
  54. Demand elasticity The degree to which demand changes relative to a change in price.
  55. Demand Power see Peak Power
  56. Demand responsiveness/demand response A change in demand for a good or service in response to a change in price for the good or service.
  57. Demand scheduling Method of irrigation scheduling whereby water is delivered to users as needed and which may vary in flow rate, frequency and duration.
  58. Demand(ed) Factor The ratio of the maximum demand on an electricity generating and distribution system to the total connected load on the system; usually expressed as a…
  59. Demand-side management Specific actions taken by utility companies, their regulators, and other entities to induce, influence, or compel consumers to reduce their energy…
  60. Demand-Side Management (DSM) The process of managing the consumption of energy, generally to optimize available and planned generation resources.
  61. deme A group of organisms in the same taxon.
  62. Demersal Fish eggs or organisms that hatch on the bottom of a lake or stream.
  63. demineralize To remove the mineral content (salts, ions) from a substance, especially water. Removal methods include distillation, electrodialysis and ion exchange.
  64. Demographic Related to the vital statistics of human populations (size, density, growth, distribution, etc.) and the effect of these on social and economic conditions.
  65. Demographics Relating to the statistical study of human populations.
  66. denaturant A substance that makes ethanol unfit for consumption.
  67. Denature To induce structural alterations that disrupt the biological activity of a molecule.
  68. Denatured Ethanol that has had a substance added to make it unfit for human consumption.
  69. denatured DNA Double-stranded DNA that has been converted to single strands by breaking the hydrogen bonds linking complementary nucleotide pairs. Often reversible.
  70. denatured protein Altering the in vivo conformation of a protein by heat or salt treatment, thereby destroying its biological activity.
  71. denaturing gradient gel electrophoresis (Abbreviation: DGGE ). An electrophoresis method for separating similar sized DNA fragments on the basis of their sequence, by applying across the gel a…
  72. dendrimer A polymer that repeatedly branches until stopped by the physical constraint of having formed a complete, hollow sphere.
  73. Dendrite Extension of a nerve cell, typically branched and relatively short, that receives stimuli from other nerve cells.
  74. Dendrites Thin branch-like growth of ice on the water surface.
  75. Dendritic Channel pattern of streams with tributaries that branch to form a tree-like pattern.
  76. Dendritic Web Technique A method for making sheets of polycrystalline silicon in which silicon dendrites are slowly withdrawn from a melt of silicon whereupon a web of silicon…
  77. denitrification A chemical process in which nitrates in the soil are reduced to molecular nitrogen, which is released to the atmosphere.
  78. Dense Fog Advisory Issued when fog reduces visibility to 1/8 mile or less over a widespread area.
  79. Densification A mechanical process to compress biomass (usually wood waste) into pellets, briquettes, cubes, or densified logs.
  80. Density The average number of people, families, or housing units on one unit of land. Density is also expressed as dwelling units per acre.
  81. Density bonus Allows developers to build in specified areas densities that are higher than normally allowed.
  82. Density Current A flow of water maintained by gravity through a large body of water, such as a reservoir or lake, and retaining its unmixed identity because of a…
  83. Density Fluctuations in Matter Regions of greater and lesser mass density, which can form into structure such as galaxies, clusters, etc.
  84. Density gradient centrifugation High-speed centrifugation in which molecules "float" at a point where their density equals that in a gradient of cesium chloride or sucrose.
  85. Density of Snow The ratio, expressed as a percentage, of the volume which a given quantity of snow would occupy if it were reduced to water, to the volume of the snow.
  86. Dental pulp The soft part inside a tooth, containing blood vessels and nerves.
  87. Dentate. See baffle block.
  88. deoxyadenosine See: adenosine, dATP.
  89. deoxycytidine A drug that protects healthy tissues from the toxic effects of anticancer drugs.
  90. deoxyguanosine See: guanosine, dGTP.
  91. deoxyribonuclease See: DNase.
  92. deoxyribonucleic acid (dee-OK-see-RY-boh-noo-KLEE-ik A-sid) The molecules inside cells that carry genetic information and pass it from one generation to the next.
  93. Deoxyribonucleic Acid (DNA) a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses.
  94. deoxyribonucleoside See: nucleoside.
  95. Deoxyribonucleotide See: nucleotide.
  96. Deoxyribose A type of sugar that is one component of DNA (deoxyribonucleic acid).
  97. deoxyribose (2-deoxyribose) See: ribose.
  98. deoxythymidine Strictly correct but rarely used synonym for thymidine.
  99. DEP Departure
  100. Department of Agriculture (USDA) A federal government agency involved in rural development, marketing and regulatory programs, food safety, research, education and economics, food…