Science terms starting with N

411 terms

  1. Nicked circle (relaxed circle) During extraction of plasmid DNA from the bacterial cell, one strand of the DNA becomes nicked.
  2. Niemann-Pick disease, type C (NPC) A disease that causes progressive deterioration of the nervous system by blocking movement of cholesterol within cells.
  3. Nieve Penitente A spike or pillar of compacted snow, firn or glacier ice, caused by differential melting and evaporation.
  4. nif gene cluster Group of bacterial genes responsible for the biological fixation of atmospheric nitrogen.
  5. Night The period of the day between dusk and dawn.
  6. Night-sky impact An interference with enjoyment of dark night skies resulting from light pollution.
  7. Nighttime mean rural background level Nighttime (10 p.m. to 7 a.m.) average sound level in the rural environment, from all sources, rather than a particular noise that is of interest.
  8. NIH A federal agency in the U.S. that conducts biomedical research in its own laboratories; supports the research of non-Federal scientists in universities…
  9. NIL Nothing; of no account.
  10. Nimbostratus (abbrev. NS)- A cloud of the class characterized by a formless layer that is almost uniformly dark gray; a rain cloud of the layer type, of low altitude…
  11. Nipple In anatomy, the small raised area in the center of the breast through which milk can flow to the outside.
  12. nitrate The form of nitrogen that can be used directly by plants; a major component of inorganic fertilizers.
  13. nitrification The natural process in which nitrogen in plant and animal wastes is oxidized, first to nitrites and then to nitrates, through the action of soil-borne…
  14. Nitrocellulose A membrane used to immobilize DNA, RNA, or protein, which can then be probed with a labeled sequence or antibody.
  15. nitrogen A colorless, tasteless element that comprises four-fifths of the atmosphere by volume, denoted by N2.
  16. nitrogen assimilation The incorporation of nitrogen into the cells of living organisms.
  17. Nitrogen cycle Cyclic movement of nitrogen in different chemical forms from the environment, to organisms, and then back to the environment.
  18. Nitrogen Dioxide This compound of nitrogen and oxygen is formed by the oxidation of nitric oxide (NO) which is produced by the combustion of solid fuels.
  19. Nitrogen dioxide (NO<sub>2</sub>) A toxic, reddish-brown gas that is a strong oxidizing agent, produced by combustion (as of fossil fuels).
  20. Nitrogen fixation The conversion of atmospheric nitrogen to biologically usable nitrates.
  21. Nitrogen oxide (NOx) NOx is a key pollutant in the formation of acid rain and ground-level ozone (smog).
  22. nitrogen oxides (NOx) A product of photochemical reactions of nitric oxide in ambient air, and the major component of photochemical smog.
  23. Nitrogen Oxides (NOx) The products of all combustion processes formed by the combination of nitrogen and oxygen.
  24. Nitrogenous base The purines (adenine and guanine) and pyrimidines (cytosine, and thymine or uracil ) that are present in DNA and RNA.
  25. Nitrogenous bases The purines (adenine and guanine) and pyrimidines (thymine, cytosine, and uracil) that comprise DNA and RNA molecules.
  26. Nitrous Oxide (N2O) A powerful greenhouse gas with a global warming potential of 296 times that of carbon dioxide (CO2).
  27. Nitrous Oxide (N<sub>2</sub>O) A powerful greenhouse gas with a global warming potential most recently evaluated at 310.
  28. NLY Northerly
  29. NM Nautical Miles
  30. NMBR Number
  31. NMC National Meteorological Center
  32. NMDA receptor (N-methyl-d-aspartate receptor). A neurotransmitter receptor for excitatory synapses.
  33. NML Normal
  34. NMRS Numerous
  35. NO Abbreviation for nucleolar organizer.
  36. No action alternative The projected baseline condition, or future without. The expected future condition if no action is taken (not necessarily the same as the present…
  37. No jeopardy opinion U.S. Fish and Wildlife Service (FWS) or National Marine Fisheries Service (NMFS) opinion that an action is not likely to jeopardize the continued…
  38. No-Take Zones Areas in which all extractive activities are prohibited.
  39. NO<sub>2</sub> See Nitrogen dioxide
  40. NO<sub>x</sub> See Nitrogen oxides
  41. NOAA National Oceanic and Atmospheric Administration
  42. NOAA Weather Radio "The voice of the National Weather Service" - NOAA Weather Radio broadcasts National Weather Service warnings, watches, forecasts and other hazard…
  43. NOAA Weather Wire Mass dissemination via satellite of National Weather Service products to the media and public.
  44. Noctilucent Clouds Wavy, thin, bluish-white clouds that are best seen at twilight in polar latitudes. They form at altitudes about 80 to 90 km above the Earth's surface.
  45. Nocturnal Related to nighttime; occurring at night.
  46. Nocturnal Cooling The effect of cooling by the radiation of heat from a building to the night sky.
  47. Nocturnal Inversion Used interchangably with Radiational Inversion; a temperature inversion that develops during the night as a result of radiational cooling of the surface.
  48. Nocturnal Jet This wind speed maximum occurs just above the nocturnal inversion at night. It is typically found in the south central United States during the late…
  49. Nocturnal Thunderstorms Thunderstorms which develop after sunset. They are often associated with the strengthening of the low level jet and are most common over the Plains states.
  50. nod box A DNA sequence that controls the transcriptional regulation of Rhizobium nodulation genes.
  51. Nodal A knob-like protrusion.
  52. nodal culture The culture of a lateral bud and a section of adjacent stem tissue.
  53. node Any device connected to network. PCs, servers, and printers are all nodes on the network.
  54. nodular Term commonly used to describe the pebbly (rough) texture of a callus.
  55. nodulation The formation of nodules on the roots of legumes following colonization by symbiotic nitrogen-fixing bacteria.
  56. nodule (NOD-yool) A growth or lump that may be cancerous or noncancerous.
  57. NOGAPS Navy Operational Global Atmospheric Prediction System; a 144-hour numerical model of the atmosphere run by the U.S. Navy twice daily.
  58. NOHRSC In hydrologic terms, the National Operational Hydrologic Remote Sensing Center.
  59. Noise Any unwanted sound that interferes with speech and hearing, causes damage to hearing, or annoys a person.
  60. Noise criteria Quantitative noise limits, below which it is acceptable for people to hear. Typically, noise criteria are specified in ordinances, regulations, or…
  61. Nominal Capacity The approximate energy producing capacity of a power plant, under specified conditions, usually during periods of highest load.
  62. Nominal diameter An approximate measurement of the diameter of a pipe. Although the nominal diameter is used to describe the size or diameter of a pipe, it is usually not…
  63. Nominal dollars Dollar value in the indicated year, not adjusted for inflation.
  64. Nominal Price The price paid for goods or services at the time of a transaction; a price that has not been adjusted to account for inflation.
  65. Nominal size The approximate dimension(s) of standard materials.
  66. non repetitive DNA/RNA A nucleotide sequence which does not include a significant proportion of repetitive sequences of nucleotide s.
  67. non-additive genetic variation The proportion of the total genetic variation in a population that does not respond to simple mass selection and that causes specific pairwise crosses to…
  68. non-autonomous A term referring to biological units that cannot function by themselves; such units require the assistance of another unit, or "helper".
  69. non-coding DNA The strand of DNA that does not carry the information necessary to make a protein.
  70. non-coding strand See: antisense DNA.
  71. non-directiveness The process by which genetic counselors advise clients toward a certain test or outcome, particularly related to child-bearing issues, without pressure or…
  72. non-disjunction Failure of separation of homologous chromosomes or chromatids in mitosis or meiosis, resulting in too many chromosomes in some daughter cells and too few…
  73. non-histone chromosomal protein In chromosomes, all of the proteins except the histones.
  74. non-linear a system that is not describable as the sum of its parts and, as a result, is difficult to predict.
  75. Non-Methane Volatile Organic Compounds (NMVOCs) Organic compounds, other than methane, that participate in atmospheric photochemical reactions.
  76. Non-Myeloablative ("Mini") Stem Cell Transplant A method used to prime a patient for a stem cell transplant by employing lower doses of chemotherapy and/or radiotherapy to damage the leukemia-producing…
  77. Non-point source Large land area such as crop fields and urban areas that discharge pollutant into surface and underground water over a large area. See point source.
  78. Non-point source pollution Pollution whose source is not specific in location; the sources of the pollutant discharge are dispersed, not well defined or constant.
  79. Non-Point Source Pollution (NPS) Pollution that cannot be identified as coming from a specific source and thus cannot be controlled through the issuing of permits.
  80. Non-potable Water that may contain objectionable pollution, contamination, minerals, or infective agents and is considered unsafe and/or unpalatable for drinking.
  81. Non-reimbursable Cost of constructing, operating, or maintaining a Reclamation project that is borne by the Federal taxpayer and is not reimbursed by any other individual…
  82. non-renewable resource A non-renewable energy resource is one that cannot be replaced as it is used. Although fossil fuels, like coal and oil, are in fact fossilized biomass…
  83. non-target organism An organism which is affected by a treatment (e.g. pesticide application) for which it was not the intended recipient.
  84. non-template strand The non-transcribed strand of DNA. Synonyms: sense strand, coding strand
  85. Non-uniform flow The velocity varies with position.
  86. Non-Uniform Sky Condition A localized sky condition which varies from that reported in the body of the report.
  87. Non-Uniform Visibility A localized visibility which varies from that reported in the body of the report.
  88. Non-Utility Generator/Power Producer A class of power generator that is not a regulated power provider and that has generating plants for the purpose of supplying electric power required in…
  89. Non-utility generators (NUG's) Facilities for generating electricity that are not owned exclusively by an electric utility and which operate connected to an electric utility system.
  90. non-virulent agent See: attenuated vaccine.
  91. Nonattainment Area The EPA's designation for an air quality control region (or portion thereof) in which ambient air concentrations of one or more criteria pollutants exceed…
  92. Nonattainment area (NAA) A geographic area in which air quality is worse than that allowed by federal air pollution standards.
  93. Nonbiodegradable Substance that cannot be broken down in the environment by natural processess. See biodegradable.
  94. Noncommercial species Tree species that do not normally develop into suitable trees for conventional forest products because of small size, poor form, or inferior quality.
  95. Noncondensing, controlled extraction turbine A turbine that bleeds part of the main steam flow at one (single extraction) or two (double extraction) points.
  96. Nonconsumptive water uses Water uses that do not substantially deplete water supplies, including swimming, boating, waterskiing, fishing, maintenance of stream related fish and…
  97. Nonfirm commercial energy Energy periodically available for sale at lower than firm power rates. All energy which cannot be considered as firm.
  98. Nonfirm power Power that is not available continuously and may be interruptible. This power may be marketed on a short-term basis.
  99. Nongame species Those species not commonly harvested either for sport or profit.
  100. Nonlinearities Occur when changes in one variable cause a more than proportionate impact on another variable.