ExpertGlossary terms starting with P

3,647 terms

phonetic index A listing organized by the sound of a word rather than its spelling
Phonetic search Phonetic search is the analysis of words that are pronounced similarly in order to detect all possible variants.
phonon A quantum of acoustic energy, the level of which is a function of the frequency of the acoustic wave.
phonon absorption Absorption of light energy by its conversion to vibrational energy. Note: Phonon absorption determines the fundamental, i.e.
Phosphatase An enzyme that hydrolyzes esters of phosphoric acid, removing a phosphate group.
phosphate (FOS-fayt) A substance that contains phosphorus, a nonmetal chemical element. Phosphate may be used to treat a high level of calcium in the blood.
phosphatidylinositol-3 kinase A type of enzyme that transmits signals in cells and that helps control cell growth.
phosphodiester (phospho-diester) bond A bond in which a phosphate group joins adjacent carbons through ester linkages.
Phosphodiester bond A bond in which a phosphate group joins adjacent carbons through ester linkages.
phospholipase A2 An enzyme which degrades type A2 phospholipids.
phospholipid A lipid (fat) that contains phosphorus. Phospholipids are a major part of cell membranes.
phospholipid complex A chemical or drug that is attached to a lipid (fat) that contains phosphorus.
phosphoric (FOS-for-ric) Having to do with or containing the element phosphorus.
phosphorolysis The cleavage of a bond by orthophosphate; analogous to hydrolysis referring to cleavage by water.
Phosphorous A chemical element used as a dopant in making n-type semiconductor layers. An essential chemical food element that can contribute to the eutrophication of…
phosphorus (FOS-for-us) A nonmetallic element that is found in the blood, muscles, nerves, bones, and teeth and is a component of adenosine triphosphate (ATP; the…
phosphorus-32 A radioactive form of phosphorus used in the treatment of cancer. It is also used to help locate areas of DNA damage.
Phosphorylation The addition of a phosphate group to a compound.
PHOTINT Photographic Intelligence.
Photo ID To be presented by a voter when voting. Acceptable forms of ID include a Texas driver’s license, a Texas DPS-issued personal identification card, a U.S.
photo laboratory process The chemical process of converting a latent image in an emulsion layer to a visible, stable image.
photo-bioreactor Bioreactor dependent on sunlight, which is taken up by its content of plant material, usually algae.
photoactivity The effect produced when certain substances are exposed to light. In cancer treatment, some drugs become active when exposed to light and are then able to…
photoautotroph See:.
Photobiological Hydrogen Production A hydrogen production process that process uses algae. Under certain conditions, the pigments in certain types of algae absorb solar energy.
Photochemical A chemical reaction resulting from exposure to radiant energy or light. 224
Photochemical Smog Air pollution containing ozone and other reactive chemical compounds formed by the reaction of nitrogen oxides and hydrocarbons in the presence of…
photocoagulation (FOH-toh-koh-A-gyuh-LAY-shun) The use of an intense beam of light, such as a laser, to seal off blood vessels or destroy tissue.
photoconductive effect In certain materials, the phenomenon that results in photoconductivity.
photoconductivity In certain materials, the increase in electrical conductivity that results from increases in the number of free carriers generated when photons are…
photoconversion Conversion of light into other forms of energy by chemical, biological, or physical processes.
Photocurrent An electric current induced by radiant energy.
photodetector (PD) A transducer capable of accepting an optical signal and producing an electrical signal containing the same information as in the optical signal.
photodiode A semiconductor diode that produces, as a result of the absorption of photons, (a) a photovoltage or (b) free carriers that support the conduction of…
photodynamic therapy (FOH-toh-dy-NA-mik THAYR-uh-pee) Treatment with drugs that become active when exposed to light. These activated drugs may kill cancer cells.
Photoelectric Cell A device for measuring light intensity that works by converting light falling on, or reach it, to electricity, and then measuring the current; used in…
Photoelectric Effect The process whereby a gamma ray (or x-ray photon) with energy somewhat greater than that of the binding energy of an electron in an atom, transfers all…
Photoelectrochemical Cell A type of photovoltaic device in which the electricity induced in the cell is used immediately within the cell to produce a chemical, such as hydrogen…
Photoelectrolysis Hydrogen Production The production of hydrogen using a photoelectrochemical cell.
Photofrin (FOH-toh-frin) A drug used to treat some types of cancer. When absorbed by cancer cells and exposed to light, Photofrin becomes active and kills the…
Photogalvanic Processes The production of electrical current from light.
Photogrammetry Techniques of obtaining precise measurements from images. This process can derive elevation from specially created stereo pairs of aerial photos.
photographic records Records that take the form of pictures or photographs, sometimes with related textual records.
photoheterotroph See: heterotroph.
Photon A photon is both a wave and a particle. A beam of light is composed of these particles.
photon noise In an optical communication link, noise attributable to the statistical nature of optical quanta. [FAA] See quantum noise.
photon-beam radiation (FOH-ton beem RAY-dee-AY-shun) A type of radiation therapy that reaches deep tumors with high-energy x-rays made by a machine called a linear accelerator.
photonic Referring to or using opto-electronic, electro-optic, or magneto-optic phenomena.
photonic computer A variety of computer in which the electronic circuits (which process data serially) are replaced by faster and more powerful photonic circuits (which can…
photonic switching The use of photonic devices rather than electronic devices to make or break connections within integrated circuits.
photonics The science of generating and harnessing light as well as other forms of radiant energy whose quantum unit is the photon.
photoperiod The length of daylight or period of daily illumination provided for growth.
photoperiodism The photoperiod required by a plant to switch from the vegetative to the reproductive stage.
photopheresis (FOH-toh-fuh-REE-siss) A procedure in which blood is removed from the body and treated with ultraviolet light and drugs that become active when exposed to…
photophobia (FOH-toh-FOH-bee-uh) A condition in which the eyes are more sensitive than normal to light.
photophosphorylation The formation of ATP from ADP and inorganic phosphate using light energy harvested by photosynthesis.
photoreactivation A light dependent DNA repair process.
photosensitive recording Facsimile recording by the exposure of a photosensitive surface to a signal-controlled light beam or spot.
photosensitizer (FOH-toh-SEN-sih-ty-zer) A drug used in photodynamic therapy. When absorbed by cancer cells and exposed to light, the drug becomes active and kills the…
photosensitizing agent (FOH-toh-SEN-sih-ty-zing...) A drug used in photodynamic therapy. When absorbed by cancer cells and exposed to light, the drug becomes active and kills…
Photosphere The Sun’s surface, from which the light we actually see (with the human eye) is emitted. Temperatures average 5,800 K (9,900°F).
photosynthate The carbohydrates and other compounds produced in photosynthesis.
Photosynthesis A chemical process by which green plants synthesize organic compounds from carbon dioxide and water in the presence of sunlight.
photosynthetic Able to use sunlight energy to convert atmospheric carbon dioxide into organic compounds.
photosynthetic efficiency Efficiency of converting light energy into organic compounds.
photosynthetic photon flux (Abbreviation: PPF). A measure of the intensity of light utilized by plants for photosynthetic activity.
photosynthetically active radiation (Abbreviation: PAR). The part of the radiant energy that is capturable by natural photosynthetic systems (approximately equivalent to the natural light…
phototesting (FOH-toh-TES-ting) Special tests used to measure the reaction of the skin to ultraviolet radiation.
phototherapy (FOH-toh-THAYR-uh-pee) The treatment of disease with certain types of light. Phototherapy can use lasers, LED, fluorescent lamps, and ultraviolet or…
phototoxicity (FOH-toh-tok-SIH-sih-tee) A condition in which the skin or eyes become very sensitive to sunlight or other forms of light.
phototropism The tendency of plants to direct shoot growth towards the source of light.
Photovoltaic A system that converts direct sunlight to electricity using semi-conductor materials.
Photovoltaic (Conversion) Efficiency The ratio of the electric power produced by a photovoltaic device to the power of the sunlight incident on the device.
Photovoltaic (PV) Literally, "light" (photo) and "electricity" (voltaic). The class of equipment used to generate electricity directly from sunlight.
Photovoltaic (PV) array An interconnected system of PV modules that function as a single electricity-producing unit.
Photovoltaic (PV) cell The smallest semiconductor element within a PV module that converts incident sunlight into electrical energy (direct current voltage and current).
Photovoltaic (PV) facility A solar energy facility that uses photovoltaic cells to produce electricity and that includes all components, such as the PV system, power conditioning…
Photovoltaic (PV) module An assembly of solar cells (flat-plate type) or receiver(s) and optics (concentrator type) and ancillary parts, such as interconnects and terminals…
Photovoltaic (PV) panel A collection of modules, either flat-plate or concentrator type, mechanically fastened, electrically interconnected, and designed to provide a…
Photovoltaic (PV) power plant See Photovoltaic (PV) facility
Photovoltaic (PV) receiver An assembly of one or more PV cells that accepts concentrated sunlight and incorporates means for thermal and electric energy removal.
Photovoltaic (PV) system See Photovoltaic (PV) facility
Photovoltaic (PV; Solar) Array A group of solar photovoltaic modules connected together.
Photovoltaic (Solar) Cell Treated semiconductor material that converts solar irradiance to electricity.
Photovoltaic (Solar) Module or Panel A solar photovoltaic product that generally consists of groups of PV cells electrically connected together to produce a specified power output under…
Photovoltaic (Solar) System A complete PV power system composed of the module (or array), and balance-of-system (BOS) components including the array supports, electrical…
Photovoltaic and solar thermal energy Energy radiated by the sun as electromagnetic waves (electromagnetic radiation) that is converted into electricity by means of solar (i.e.
Photovoltaic Device A solid-state electrical device that converts light directly into direct current electricity of voltage-current characteristics that are a function of the…
photovoltaic effect The production, as a result of the absorption of photons, of a voltage difference across a pn junction.
Photovoltaic Peak Watt see Peak Watt.
Photovoltaic-Thermal (PV/T) Systems A solar energy system that produces electricity with a PV module, and collects thermal energy from the module for heating.
Photovoltaics (PV) Technologies that utilize semiconducting materials that convert sunlight directly into electricity.
PHP PHP Hypertext Preprocessor is an open source server side scripting language used to render web pages or add interactivity to them. See also: PHP.net
Phrase detection The recognition and grouping of an idiom such as "home run" or "Christmas tree".
Phrase Match Phrase Match is a form of keyword matching where an ad will be displayed if the user's search query includes the exact phrase, even if their query…
Phrase search A search for documents containing a exact sentence or phrase specified by a user.
Phrase searching A search engine may provide an option to search a set of words as a phrase, either by typing in quotation marks (""), by using a command or clicking a…
Phrasing The recognition and grouping of an idiom such as "home run" or "Christmas tree."
Phreatic surface The free surface of water seeping at atmospheric pressure through soil or rock.
Phreatic vegetation Vegetation supported by groundwater below the land surface.