ExpertGlossary terms starting with P

3,647 terms

  1. Polar low Polar low Small, shallow depression which forms mainly in winter over some high-latitude seas within a polar or arctic air mass.
  2. polar mutation A mutation that influences the functioning of genes that are downstream from the site of mutagenesis but are in the same transcription unit.
  3. Polar night Polar night In polar regions, the portion of the year when the Sun does not rise above the horizon.
  4. polar nuclei Two centrally located nuclei in the embryo sac that unite with a second sperm cell in a triple fusion.
  5. polar operation A telegraph system in which marking signals are formed by current or voltage pulses of one polarity and spacing signals by current or voltage pulses of…
  6. polar orbit An orbit for which the angle of inclination is 90o. Note: A satellite in polar orbit will pass over both the north and south geographic poles once per…
  7. Polar Orbiting Satellite A weather satellite which travels over both poles each time it orbits the Earth. It orbits about 530 miles (850 km) above the Earth's surface.
  8. polar relay A dc relay in which the direction of movement of the armature depends on the direction of the current flow.
  9. polar transport A directed movement within plants of compounds (usually endogenous plant growth regulators) mostly in one direction; polar transport overcomes the…
  10. Polar vortex Polar vortex Large-scale cyclonic circulation in the middle and upper troposphere centered generally in the polar regions.
  11. polarential telegraph system A direct-current telegraph system employing polar transmission in one direction and a form of differential duplex transmission in the other.
  12. Polarity The observed differentiation of an organism, tissue or cell into parts having opposed or contrasted properties or form.
  13. polarization Of an electromagnetic wave, the property that describes the orientation, i.e., time-varying direction and amplitude, of the electric field vector.
  14. polarization diversity Diversity transmission and reception wherein the same information signal is transmitted and received simultaneously on orthogonally polarized waves with…
  15. Polarization Radar A radar which takes advantage of ways in which the transmitted waves' polarization affect the backscattering.
  16. polarization-maintaining (PM) optical fiber An optical fiber in which the polarization planes of lightwaves launched into the fiber are maintained during propagation with little or no cross-coupling…
  17. polarization-preserving (PP) optical fiber Synonym polarization-maintaining optical fiber.
  18. pole cells A group of cells in the posterior of Drosophila embryos that are precursors to the adult germ line.
  19. Pole Position The front position in the start of a race. In NASCAR, the fastest qualifying car gets to start here.
  20. Police Certificate These certificates record criminal activity on the part of an applicant. They are required of visa applicants for all countries where an applicant has…
  21. Police District Police jurisdictions. See also Police Service Areas (PSA).
  22. Police Officers Retirement System (PORS) The name of the retirement system covering police officers, firefighters, peace officers, probate judges, and magistrates. See PORS for more information.
  23. Police Service Area (PSA) Every resident lives in a Police Service Area, and every PSA has a team of police officers and officials assigned to it.
  24. Policy The contract form issued by the company to explain the coverage provided. It is a legal document.
  25. policy committees Each party policy committee provides research and other services to Senators and also serves as a forum for discussion of party legislative strategy.
  26. Policy Dividend (See Dividend.)
  27. Policy Loan Under an insurance policy, the amount that can be borrowed at a specified rate of interest from the issuing company by the policyholder, who uses the…
  28. Policy Management Authority (PMA) Body established to oversee the creation and update of Certificate Policies, review Certification Practice Statements, review the results of CA audits for…
  29. policy manual A publication that states the course of action to be followed by an organization, unit, or department in conducting its activities.
  30. Policy Mapping Recognizing that, when a CA in one domain certifies a CA in another domain, a particular certificate policy in the second domain may be considered by the…
  31. Policy owner The person or party who owns an individual insurance policy. This person may be the insured, the beneficiary, or another person.
  32. Policy period The amount of time an insurance contract or policy provides coverage.
  33. Policy Year A 12-month period of benefits coverage under an individual health insurance plan. This 12-month period may not be the same as the calendar year.
  34. policy, folder policy Restrictions placed on a folder or other object that limit access to it, or that limit operations that can be performed on the object.
  35. policy-based automation policies automate resource management based on business-defined conditions such as time of day, trouble alarms, and capacity or availability issues by…
  36. Policy-based Management A method of managing system behavior or resources by setting "policies" (often in the form of "if-then" rules) that the system interprets.
  37. Policyholder or policy owner If you own an insurance contract or policy, you are a policyholder, also known as the policy owner.
  38. polifeprosan 20 carmustine implant A biodegradable wafer that is used to deliver the anticancer drug carmustine directly into a brain tumor site after the tumor has been removed by surgery.
  39. Polishing treatment The final sewage treatment process to further reduce BOD5, suspended solids, and other pollutants.
  40. Politeness Window In order not to overburden any particular server, most search engine spiders limit their access to each server.
  41. Political Action Committee (PAC) PAC's are political groups that are not formally related to a particular political party, but are associated with other groups (like labor unions…
  42. Political Party An organized group of people with common values and goals, who try to get their candidates elected to office.
  43. Political Subdivision A county, city, or school district or any other governmental entity that: embraces a geographic area with a defined boundary; exists for the purpose of…
  44. Poll Watcher A person appointed by a candidate or political action committee to observe the conduct of an election on behalf of a candidate, a political party, or the…
  45. pollen Mature microspores of seed plants.
  46. pollen culture The in vitro culture and germination of pollen grains to generate haploid plants. See: anther culture;.
  47. pollen grain The mature microspore, produced in the pollen sac of angiosperms or the microsporangium of gymnosperms.
  48. pollination Transfer of pollen from anther to stigma in the process of fertilization in angiosperms; transfer of pollen from male to female cone in the process of…
  49. polling The process of repeatedly testing until a condition becomes true. Polling can be inefficient if the time between tests is short compared with the time it…
  50. Polling Place The room or building in which voting is being conducted.The governing body of each political subdivision authorized to hold elections shall designate the…
  51. Polling the jury The act, after a jury verdict has been announced, of asking jurors individually whether they agree with the verdict.
  52. Pollutant Any inorganic or organic substance that contaminates air, water or soil. Generally, any substance introduced into the environment that adversely affects…
  53. Pollution A resource that is out of place. Generally, the presence of matter or energy whose nature, location or quantity produces undesired environmental effects.
  54. Poly(A) polymerase Catalyzes the addition of adenine residues to the 3' end of pre-mRNAs to form the poly(A) tail. (See Polymerase.)
  55. poly-(A) tail See: polyadenylation.
  56. poly-ICLC (PAH-lee ...) A substance that is being studied in the treatment of cancer and for its ability to stimulate the immune system.
  57. polyacrylamide gel Inert electrophoresis matrix, formed by the polymerization of acrylamide monomer in the presence of the cross-linker N,N'-methylene-bis-acrylamide.
  58. Polyacrylamide gel electrophoresis Electrophoresis through a matrix composed of a synthetic polymer, used to separate proteins, small DNA, or RNA molecules of up to 1000 nucleotides.
  59. polyadenylation Post-transcription al addition of multiple adenine residues to the 3' end of eukaryotic mRNA. Also called poly-(A) tailing.
  60. polycistronic A single mRNA that contains the information necessary for the production of more than one polypeptide. Particularly characteristic of prokaryotic mRNA s.
  61. Polyclonal antibodies A mixture of immunoglobulin molecules secreted against a specific antigen, each recognizing a different epitope.
  62. polyclonal antibody A serum sample that contains a mixture of distinct immunoglobulin molecules, each recognizing a different antigenic determinant of a given antigen.
  63. polycloning site See: polylinker.
  64. Polycrystalline A semiconductor (photovoltaic) material composed of variously oriented, small, individual crystals.
  65. polycystic ovary syndrome (PAH-lee-SIS-tik OH-vuh-ree SIN-drome) A condition marked by infertility, enlarged ovaries, menstrual problems, high levels of male hormones, excess hair…
  66. polycythemia vera (PAH-lee-sy-THEE-mee-uh VAYR-uh) A disease in which there are too many red blood cells in the bone marrow and blood, causing the blood to thicken.
  67. polydactyly An abnormality in which a person is born with more than the normal number of fingers or toes. See also
  68. Polydipsia Excessive thirst that is relatively chronic.
  69. Polydrug Abuse The abuse of two or more drugs at the same time, such as CNS depressants and alcohol.
  70. polyembryony The production of more than one embryo from a single egg cell (in animals) or from a range of embryogenic cell types (in plants).
  71. Polyethylene A registered trademark for plastic sheeting material that can be used as a vapor retarder. This plastic is used to make grocery bags.
  72. polyethylene glycol (Abbreviation: PEG). A polymer having the general formula HOCH2(CH2OCH2)nCH2OH and available in a range of molecular weights.
  73. polyethylene glycosylated recombinant human megakaryocyte growth and development factor (PAH-lee-EH-thih-leen gly-KAH-sih-lay-ted ree-KOM-bih-nunt HYOO-mun MEH-guh-KAH-ree-oh-site …) A form of megakaryocyte growth and development…
  74. polygalacturonase (Abbreviation: PG). An enzyme which catalyses the breakdown of pectin. A tomato engineered to contain an antisense-PG gene succeeded in delaying the onset…
  75. Polygamy Having more than one husband or wife at the same time. Polygamy is illegal under U.S. law.
  76. polygene One of a number of genes, each of small effect, which together act to determine the phenotype of a quantitative trait.
  77. Polygenic Controlled by or associated with more than one gene.
  78. Polygenic disorder Genetic disorder resulting from the combined action of alleles of more than one gene (e.g., heart disease, diabetes, and some cancers).
  79. polyglutamate camptothecin (PAH-lee-GLOO-tuh-mayt kamp-toh-THEK-in) A form of the anticancer drug camptothecin that may have fewer side effects and work better than camptothecin.
  80. polygon A coverage feature class used to represent areas. A polygon is defined by the arcs that make up its boundary and a point inside its boundary for…
  81. polygon overlay A topological overlay procedure which determines the spatial coincidence of two sets of polygon features and creates a new set of polygons based on…
  82. polygon-arc topology The topological data structure ARC/INFO uses to represent connectivity between arcs to form polygons.
  83. polyhydroxybutyrate (Abbreviation: PHB). A biopolymer, with physical properties similar to polystyrene, originally discovered in the bacterium Alcaligenes eutropus.
  84. polyinstantiation In cryptography, the existence of a cryptographic key in more than one secure physical location. [After X9.49]
  85. Polylinker A short DNA sequence containing several re- striction enzyme recognition sites that is contained in cloning vectors.
  86. polymer (PAH-lih-mer) A molecule made up of small identical molecules called monomers. The monomers are joined together in a repeating pattern.
  87. polymer-clad silica fiber Synonym plastic-clad silica fiber.
  88. polymerase An enzyme that catalyses the formation of polymers from monomers . A DNA polymerase synthesizes DNA from deoxynucleoside triphosphates using a…
  89. Polymerase (DNA) Synthesizes a double-stranded DNA molecule using a primer and DNA as a template.
  90. polymerase chain reaction (puh-LIM-eh-rayz ...) A laboratory method used to make many copies of a specific DNA sequence. Also called PCR.
  91. polymerase chain reaction (PCR) A procedure that en- zymatically amplifies a DNA polymerase. (See Polymerase.)
  92. Polymerase, DNA or RNA Enzyme that catalyzes the synthesis of nucleic acids on preexisting nucleic acid templates, assembling RNA from ribonucleotides or DNA from…
  93. polymerization The chemical fusion of a number of identical or similar monomers to form a polymer.
  94. polymery The phenomenon whereby a number of genes at different loci (which may be polygenes ) can act together to produce a single effect.
  95. Polymorphic Literally meaning having more than one form. In terms of genes it means that there are several variants (alleles) of a particular gene that occur…
  96. polymorphism (PAH-lee-MOR-fih-zum) A common variation or mutation in DNA.
  97. Polymorphisms Variant forms of a particular gene that occur simultaneously in a population.
  98. polymyositis (PAH-lee-MY-oh-SY-tis) An inflammatory disease of the muscles closest to the center of the body.
  99. polyneuritis (PAH-lee-nuh-RY-tis) Inflammation of several peripheral nerves at the same time.
  100. Polynucleotide A DNA polymer composed of multiple nucleotides. (See Nucleotide.)