| photomultiplier tube | A detector which amplifies a signal (by as much as 106) of electromagnetic radiation by an acceleration of electrons released from a photocathode through a series of dynodes; as each electron strikes a dynode stage, 3 to 4 electrons are liberated and accelerated to the subsequent dynode. (05 Mar 2000) |
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| photomyoclonus | Clonic spasms of muscles in response to visual stimuli. Origin: photo-+ G. Mys, muscle, + klonos, confused motion Hereditary photomyoclonus, photomyoclonus associated with diabetes mellitus, deafness, nephropathy, and cerebral dyfunction. (05 Mar 2000) |
| photon | <physics> A quantum unit of light energy. (09 Oct 1997) |
| photon density | The number of counted events recorded in scintigraphy per square centimeter or per square inch of imaged area. Synonym: count density. (05 Mar 2000) |
| photoncia | Any swelling resulting from the intense action of light. Origin: photo-+ G. Onkos, a mass (tumour) (05 Mar 2000) |
| photonosus | Any disease caused by excessive exposure to or unusual intensity of light, or resulting from phototoxicity or photoallergy. Synonym: photopathy. Origin: photo-+ G. Nosos, disease (05 Mar 2000) |
| photons | Discrete concentrations of energy, apparently massless elementary particles, that move at the speed of light. They are the unit or quantum of electromagnetic radiation. Photons are emitted when electrons move from one energy state to another. (12 Dec 1998) |
| photooxidase | <enzyme> Rhodoquinone accepts electrons from ubiquinone during chromatophore photooxidase activity Registry number: EC 1.6.99.- Synonym: rhodoquinone photooxidase (26 Jun 1999) |
| photopathy | Synonym: photonosus. Origin: photo-+ G. Pathos, suffering (05 Mar 2000) |
| photopeak | The characteristic energies of photons emitted by a radionuclide, used to set scanning parameters. (05 Mar 2000) |
| photoperceptive | Capable of both receiving and perceiving light. (05 Mar 2000) |
| photoperiod | <ecology> Recurring cycle of light and dark periods. The natural photoperiod is approximately 24 hours, and the ratio of light to dark hours slowly changes over the course of a year. In controlled experiments, the photoperiod is usually (but not necessarily) retained at 24 hours, and the light:dark ratio is typically constant. (09 Oct 1997) |
| photoperiodism | <biology> Events triggered by duration of illumination or pattern of light/dark cycles: often the wavelength of the illuminating light is important as for example in control of circadian rhythm in plants. See: phytochromes. (18 Nov 1997) |
| photopheresis | A process in which peripheral blood is exposed in an extracorporeal flow system to photoactivated 8-methoxypsoralen (methoxsalen) and ultraviolet light - a procedure known as puva therapy. Photopheresis is at present a standard therapy for advanced cutaneous T-cell lymphoma; it shows promise in the treatment of autoimmune diseases. (12 Dec 1998) |
| photophobia | <psychology, symptom> An abnormal visual intolerance of light. Origin: Gr. Phobos = fear (16 Mar 1998) |
| phototropic |
Phototropism or heliotropism are botanical terms for an organism response to light (in the case of heliotropism, specifically the light from the Sun). These are one of the many plant tropisms or movements in response to extermal stimuli. Growth toward a light source is a positive phototropism, while the reverse is called negative phototropism or skototropism. ...
출처: en.wikipedia.org/wiki/Phototropic
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| photoluminescence |
Fluorescence is a luminescence, i.e. optical phenomenon in cold bodies, in which a molecule absorbs a high-energy photon, and re-emits it as a lower-energy (longer-wavelength) photon. The energy difference between the absorbed and emitted photons ends up as molecular vibrations (heat). Usually the absorbed photon is in the ultraviolet, and the emitted light (luminescence) is in the visible range, but this depends on the absorbance curve and Stokes shift of the particular fluorophore. ...
출처: en.wikipedia.org/wiki/Photoluminescence
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| photometry |
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation. Usually, photometry refers to measurement over large wavelength bands of radiation; but, when not only the amount of radiation but its spectral distribution are measured the term spectrophotometry is used. ...
출처: en.wikipedia.org/wiki/Photometry_(astronomy)
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| photon |
Photon was a live action series based on the infrared tag game popular in the 1980s. The series took place on Earth and in space on various worlds and involved a young human teen named Christopher Jarvis who is a champion player of Photon. He receives a mysterious message one day while playing and is transported to the ship of Mother One, the leader of the Federation of Light a galactic amalgam of beings dedicated to playing Photon and the power of good over evil. ...
출처: en.wikipedia.org/wiki/Photon_(TV_series)
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| photoautotroph |
Phototrophs or photoautotrophs are photosynthetic algae, fungi, bacteria and cyanobacteria which build up carbon dioxide and water into organic cell materials using energy from sunlight. One product of this process is starch, which is a storage or reserve form of carbon, which can be used when light conditions are too poor to satisfy the immediate needs of the organism. ...
출처: en.wikipedia.org/wiki/Photoautotroph
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| photo | synthesis of compounds with the aid of radiant energy (especially in plants) |
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| photo | relating to or using or formed by photosynthesis |
| photo | the use of strong light to treat acne or hyperbilirubinemia of the newborn |
| photo | green and purple bacteria |
| photo | green and purple bacteria |
| photo | an orienting response to light |
| photo | producing a voltage when exposed to radiant energy (especially light) |
| photo | a cell that converts solar energy into electrical energy |