• 0-9
  • a
  • b
  • c
  • d
  • e
  • f
  • g
  • h
  • i
  • j
  • k
  • l
  • m
  • n
  • o
  • p
  • q
  • r
  • s
  • t
  • u
  • v
  • w
  • x
  • y
  • z
  • photographic printing paper (photography)

    technology of photography: Printing papers: Papers for enlarging and contact printing are produced in grades of differing exposure range—i.e., ratios of shortest to longest exposure to produce the lightest tone and a full black, respectively. The various grades yield prints of a normal tone range from negatives of different…

  • photographic slide (photography)

    history of photography: Colour photography: Because Autochrome was a colour transparency and could be viewed only by reflected light, however, researchers continued to look for improvements and alternative colour processes.

  • Photographic Views of Sherman’s Campaign (photographic book by Barnard)

    George N. Barnard: In 1866 he published Photographic Views of Sherman’s Campaign, which is considered one of the most important photographic books from the period. Barnard later worked as a photographer in numerous locations—including Chicago, where he set up a studio that was subsequently destroyed in the fire of 1871. He also…

  • photographic zenith tube (instrument)

    time: Time determination: The photographic zenith tube (PZT) is a telescope permanently mounted in a precisely vertical position. The light from a star passing almost directly overhead is refracted by the lens, reflected from the perfectly horizontal surface of a pool of mercury, and brought to a focus just…

  • Photographie judiciaire, La (work by Bertillon)

    Alphonse Bertillon: …his method, one work being La Photographie judiciaire (1890). A biography by H.T.F. Rhodes, Alphonse Bertillon: Father of Scientific Detection, was published in 1954.

  • Photographischer Stern-Atlas (astronomy)

    astronomical map: Atlases for stargazing: The German astronomer Hans Vehrenberg’s Photographischer Stern-Atlas (1962–64), covering the entire sky in 464 sheets, each 12° square, has probably reached wider use than any other photographic atlas because of its quality and comparatively modest cost.

  • photography

    History of photography, method of recording the image of an object through the action of light, or related radiation, on a light-sensitive material. The word, derived from the Greek photos (“light”) and graphein (“to draw”), was first used in the 1830s. This article treats the historical and

  • photography, technology of

    Technology of photography, equipment, techniques, and processes used in the production of photographs. The most widely used photographic process is the black-and-white negative–positive system (Figure 1). In the camera the lens projects an image of the scene being photographed onto a film coated

  • photogravure printing (printing)

    printing: Photosensitivity: Niepce (1820s): This marked the origins of photogravure and led to both the invention of photography (between 1829 and 1838) and the use of photographic processes for the printed reproduction of photographs.

  • photoinitiator (chemical compound)

    adhesive: Ultraviolet-cured adhesives: …low-molecular-weight prepolymer combined with a photoinitiator. Photoinitiators are compounds that break down into free radicals upon exposure to ultraviolet radiation. The radicals induce polymerization of the monomer and prepolymer, thus completing the chain extension and cross-linking required for the adhesive to form. Because of the low process temperatures and very…

  • photoionization (physics)

    Photo-ionization, the interaction of electromagnetic radiation with matter resulting in the dissociation of that matter into electrically charged particles. The simplest example, the photoelectric effect (q.v.), occurs when light shines on a piece of metal, causing the ejection of electrons.

  • photoisomerization (biochemistry)

    photochemical reaction: Photoisomerization: In photoisomerization no chemical bonds are broken, but the molecule changes shape. For example, absorption of optical radiation by a stilbene molecule converts the central double bond from trans to cis. As in photodissociation, this is caused by the electron distribution in the excited…

  • photojournalism

    history of photography: Photojournalism: From the outset, photography served the press. Within weeks after the French government’s announcement of the process in 1839, magazines were publishing woodcuts or lithographs with the byline “from a daguerreotype.” In fact, the two earliest illustrated weeklies—The Illustrated London News, which started in…

  • Photoline (printing)

    printing: Photocomposition: In 1915 the Photoline, a photographic equivalent of the Ludlow, assembled matrices of transparent letters in a composing stick in order to film each line of the heading.

  • photolithoautotroph (biology)

    life: Energy, carbon, and electrons: …nucleated organisms, eukaryotes, are either photolithoautotrophs (i.e., algae and plants) that derive energy from light or minerals or chemo-organoheterotrophs (animals, fungi, and most protists) that derive energy and carbon from preformed organic compounds (food).

  • photolithographic mask (photographic printing device)

    integrated circuit: Photolithography: …is controlled by using a mask. A mask is made by applying a thick deposit of chrome in a particular pattern to a glass plate. The chrome provides a shadow over most of the wafer, allowing “light” to shine through only in desired locations. This enables the creation of extremely…

  • photolithography

    integrated circuit: Photolithography: In order to alter specific locations on a wafer, a photoresist layer is first applied (as described in the section Deposition). Photoresist, or just resist, typically dissolves in a high-pH solution after exposure to light (including ultraviolet radiation or X-rays

  • photolithotroph (biology)

    nutrition: Nutritional patterns in the living world: Higher plants, for example, are photolithotrophic; i.e., they utilize light energy, with the inorganic compound water serving as the ultimate electron donor. Certain photosynthetic bacteria that cannot utilize water as the electron donor and require organic compounds for this purpose are called photoorganotrophs. Animals, according to this classification, are chemoorganotrophs;…

  • photolithotrophy (biology)

    nutrition: Nutritional patterns in the living world: Higher plants, for example, are photolithotrophic; i.e., they utilize light energy, with the inorganic compound water serving as the ultimate electron donor. Certain photosynthetic bacteria that cannot utilize water as the electron donor and require organic compounds for this purpose are called photoorganotrophs. Animals, according to this classification, are chemoorganotrophs;…

  • photoluminescence (physics)

    Photoluminescence, emission of light from a substance as a result of absorption of electromagnetic radiation; such a substance is called a phosphor (q.v.), and the emitted light usually has a longer wavelength than the incident

  • photolyase (enzyme)

    human genetic disease: Ultraviolet radiation: …repaired by an enzyme called photolyase, which utilizes the energy of longer wavelengths of light to cleave the dimers. However, people with a defect in the gene coding for photolyase develop xeroderma pigmentosum, a condition characterized by extreme sensitivity to sunlight. These individuals develop multiple skin cancers on all areas…

  • photolyphic engraving (photography)

    William Henry Fox Talbot: …instantaneous photographs, and his “photolyphic engraving” (patented in 1852 and 1858), a method of using printable steel plates and muslin screens to achieve quality middle tones of photographs on printing plates, was the precursor to the development in the 1880s of the more successful halftone plates.

  • photolysis (chemical reaction)

    Photolysis, chemical process by which molecules are broken down into smaller units through the absorption of light. The best-known example of a photolytic process is the experimental technique known as flash photolysis, employed in the study of short-lived chemical intermediates formed in many

  • photomacrography

    technology of photography: Close-range and large-scale photography: Near photography to reveal fine texture and detail covers several ranges: (1) close-up photography at image scales between 0.1 and 1 (one-tenth to full natural size); (2) macrophotography between natural size and 10 to 20× magnification, using the camera lens on…

  • photomap (cartography)

    surveying: Aerial surveying: …printed directly to form a photomap. For flat areas this operation requires simply cutting and pasting the photographs together into a mosaic. For greater accuracy the centres of the photographs may be aligned by the use of slotted templates as described above to produce a photomap called a controlled mosaic.

  • photomask (photographic printing device)

    integrated circuit: Photolithography: …is controlled by using a mask. A mask is made by applying a thick deposit of chrome in a particular pattern to a glass plate. The chrome provides a shadow over most of the wafer, allowing “light” to shine through only in desired locations. This enables the creation of extremely…

  • photometer (instrument)

    Photometer, device that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Such devices are generally transducers that convert an electric current into a mechanical indication—e.g., a pointer moving across a dial. The

  • Photometric Researches (work by Peirce)

    Charles Sanders Peirce: Life.: …Annals (1878) there appeared his Photometric Researches (concerning a more precise determination of the shape of the Milky Way Galaxy).

  • photometric transit method (astronomy)

    extrasolar planet: Detection of extrasolar planets: A complementary technique is transit photometry, which measures drops in starlight caused by those planets whose orbits are oriented in space such that they periodically pass between their stars and the telescope; transit observations reveal the sizes of planets as well as their orbital periods. Radial velocity data can…

  • photometry (astronomy)

    Photometry, in astronomy, the measurement of the brightness of stars and other celestial objects (nebulae, galaxies, planets, etc.). Such measurements can yield large amounts of information on the objects’ structure, temperature, distance, age, etc. The earliest observations of the apparent

  • photomicrography (biology)

    Photomicrography, photography of objects under a microscope. Such opaque objects as metal and stone may be ground smooth, etched chemically to show their structure, and photographed by reflected light with a metallurgical microscope. Biological materials may be killed, dyed so that their structure

  • photomontage (photography)

    Photomontage, composite photographic image made either by pasting together individual prints or parts of prints, by successively exposing individual images onto a single sheet of paper, or by exposing the component images simultaneously through superimposed negatives. In the 1880s the juxtaposition

  • photomultiplier tube (electronics)

    Photomultiplier tube, electron multiplier tube that utilizes the multiplication of electrons by secondary emission to measure low light intensities. It is useful in television camera tubes, in astronomy to measure intensity of faint stars, and in nuclear studies to detect and measure minute

  • photon (subatomic particle)

    Photon, minute energy packet of electromagnetic radiation. The concept originated (1905) in Albert Einstein’s explanation of the photoelectric effect, in which he proposed the existence of discrete energy packets during the transmission of light. Earlier (1900), the German physicist Max Planck had

  • Photon-Lumitype (printing)

    printing: Functional phototypesetters: Photon-Lumitype was the first phototypesetter to introduce the selection and photographing of the character in a rapid circular movement without interrupting continuity.

  • Photon-Lumitype 713 (printing)

    printing: Second generation of phototypesetters: functional: The Photon-Lumitype 713 (1957) also performs at the rate of 70,000 to 80,000 characters per hour. But at this speed the technique of using a rotary matrix case reaches its limit because of the problems posed by centrifugal force. The Lumizip 900 (1959) introduced a further…

  • Photon-Lumizip (printing)

    printing: Functional phototypesetters: Photon-Lumizip is based on a different principle. The performance speed of drum phototypesetters can hardly be increased because of the technical problems posed by the rapid rotation of the drum. To increase speed, the Lumizip abandoned rotary movement. The type matrices are stationary and are…

  • photonic mast (sensor system)

    submarine: Postwar developments: …is being replaced by so-called photonic masts, or optronic masts. These are sensor systems that, like the periscope, project upward to the surface from the submarine’s sail; however, unlike the periscope, they relay optical, infrared, and radiowave information to the control room electronically, without the need for any hardware to…

  • photonic system

    materials science: Photonic materials: Computers and communications systems have been dominated by electronic technology since their beginnings, but photonic technology is making serious inroads throughout the information movement and management systems with such devices as lasers, light-emitting diodes, photodetecting diodes, optical switches, optical amplifiers, optical modulators, and…

  • photonuclear reaction (physics)

    Photodisintegration, in physics, nuclear reaction in which the absorption of high-energy electromagnetic radiation (a gamma-ray photon) causes the absorbing nucleus to change to another species by ejecting a subatomic particle, such as a proton, neutron, or alpha particle. For example, m

  • photoorganotroph (biology)

    nutrition: Nutritional patterns in the living world: …for this purpose are called photoorganotrophs. Animals, according to this classification, are chemoorganotrophs; i.e., they utilize chemical compounds to supply energy and organic compounds as electron donors.

  • photoorganotrophy (biology)

    nutrition: Nutritional patterns in the living world: …for this purpose are called photoorganotrophs. Animals, according to this classification, are chemoorganotrophs; i.e., they utilize chemical compounds to supply energy and organic compounds as electron donors.

  • photoperiodism (biology)

    Photoperiodism, the functional or behavioral response of an organism to changes of duration in daily, seasonal, or yearly cycles of light and darkness. Photoperiodic reactions can be reasonably predicted, but temperature, nutrition, and other environmental factors also modify an organism’s

  • photophobia (pathology)

    radiation: Effects on the eyes: …condition that is known as photophobia. The pain appears to be associated with reflex movements of the iris and reflex dilation of the blood vessels of the conjunctiva. Workers exposed to ultraviolet-light sources or to atomic flashes need to wear protective glasses.

  • Photophone (film technology)

    history of the motion picture: Introduction of sound: …patented in 1925 as RCA Photophone. In October 1928 RCA therefore acquired the Keith-Albee-Orpheum vaudeville circuit and merged it with Joseph P. Kennedy’s Film Booking Offices of America (FBO) to form RKO Radio Pictures for the express purpose of producing sound films using the Photophone system (which ultimately became the…

  • photophore (anatomy)

    Photophore, light-emitting organ present in fireflies and certain other bioluminescent animals. Photophores are glandular in origin and produce light by a chemical reaction. Photophores vary in size and form but often contain such structures as lenses, reflecting layers, and filters in addition to

  • photophosphorylation (physiology)

    photosynthesis: The process of photosynthesis: the conversion of light energy to ATP: …photosynthesis is referred to as photophosphorylation, as opposed to oxidative phosphorylation in the electron-transport chain in the mitochondrion.

  • photopigment (biochemistry)

    photoreception: Photopigments: The photopigments that absorb light all have a similar structure, which consists of a protein called an opsin and a small attached molecule known as the chromophore. The chromophore absorbs photons of light, using a mechanism that involves a change in its configuration. In

  • photopolymer process (photography)

    technology of photography: Colloid and photopolymer processes: A comparatively early non-silver process depended on organic colloid (gum or gelatin) treated with a bichromate. Exposure to light hardened the gelatin, rendering it insoluble, while unexposed portions could be washed away with warm water, leaving a relief image.

  • photoprotection (biochemistry)

    photochemical reaction: Photoprotection: Photoprotection involves the nonradiative dissipation of excess electronic energy to avoid damaging chemical processes from the excited state. The simplest example is a molecule (such as a carotenoid) that has highly efficient internal conversion so that the other competing processes (fluorescence, intersystem

  • photoprotein (biochemistry)

    Photoprotein, in biochemistry, any of several proteins that give off light upon combination with oxygen, hydrogen peroxide, or other oxidizing agents. Unlike the oxidation of luciferin, the production of light by a photoprotein requires no catalyst. Such a system occurs in Aequorea, a luminescent

  • photopsin (biology)

    visual pigment: Photopsin pigments operate in brighter light than scotopsins and occur in the vertebrate cone cells; they differ from the scotopsins only in the characteristics of the opsin fraction. The retinal1 forms are called iodopsins; the retinal2 forms cyanopsins.

  • photoradiation (physics)

    luminescence: Photoradiation in gases, liquids, and crystals: When describing chemical principles associated with luminescence, it is useful, at first, to neglect interactions between the luminescing atoms, molecules, or centres with their environment. In the gas phase these interactions are smaller than they are in the condensed…

  • photoreactivation (biology)

    Photorecovery, restoration to the normal state, by the action of visible light, of the deoxyribonucleic acid composing the hereditary material in animal skin cells and plant epidermal cells damaged by exposure to ultraviolet light. The phenomenon is also called photoreactivation, especially in

  • photorearrangement (chemistry)

    photochemical reaction: Photorearrangement: In photorearrangement, absorption of light causes a molecule to rearrange its structure in such a way that atoms are lost and it becomes another chemical species. One biologically important photorearrangement reaction is the conversion of 7-dehydrocholesterol to vitamin D in the

  • photoreception (biology)

    Photoreception, any of the biological responses of animals to stimulation by light. In animals, photoreception refers to mechanisms of light detection that lead to vision and depends on specialized light-sensitive cells called photoreceptors, which are located in the eye. The quality of vision

  • photoreceptor (anatomy)

    senses: Light senses: …vision, or photoreception, relies on photoreceptors that contain a special light-detecting molecule known as rhodopsin. Rhodopsin detects electromagnetic radiation—light with wavelengths in the range 400–700 nanometres (1 nm = 10−9m). There are some animals that can detect infrared radiation (wavelengths greater than 700 nm); for example, some

  • photoreconaissance

    Central Intelligence Agency: Organization and responsibilities: …Cold War, material gathered from aerial reconnaissance produced detailed information on issues as varied as the Soviet grain crop and the development of Soviet ballistic missiles. Information obtained through those satellites was critical to the arms control process; indeed, agreements reached during the Strategic Arms Limitation Talks (SALT) in the…

  • photorecovery (biology)

    Photorecovery, restoration to the normal state, by the action of visible light, of the deoxyribonucleic acid composing the hereditary material in animal skin cells and plant epidermal cells damaged by exposure to ultraviolet light. The phenomenon is also called photoreactivation, especially in

  • photorefractive keratectomy (surgical method)

    Photorefractive keratectomy (PRK), common surgical method that reshapes the cornea (the transparent membrane covering the front of the eye) to improve vision in patients affected by farsightedness (hyperopia) or nearsightedness (myopia). In this procedure a local anesthetic is applied to the eye

  • photoresist (electronics)

    materials science: Photoresist films: Patterning polished wafers with an integrated circuit requires the use of photoresist materials that form thin coatings on the wafer before each step of the photolithographic process. Modern photoresists are polymeric materials that are modified when exposed to radiation (either in the form…

  • photorespiration (biology)

    photosynthesis: Light intensity and temperature: …land plants, a process called photorespiration occurs, and its influence upon photosynthesis increases with rising temperatures. More specifically, photorespiration competes with photosynthesis and limits further increases in the rate of photosynthesis, especially if the supply of water is limited (see below Photorespiration).

  • photosensitivity (biology)

    drug: Dermatologic drugs: …high sensitivity to sunlight (photosensitization). Drugs capable of causing photosensitization generally exert their effects following the absorption of light energy. For example, the topical or systemic administration of methoxsalen or trioxsalen prior to exposure to the ultraviolet radiation of the Sun augments the production of melanin pigment in the…

  • photosensitization (chemistry)

    Photosensitization, the process of initiating a reaction through the use of a substance capable of absorbing light and transferring the energy to the desired reactants. The technique is commonly employed in photochemical work, particularly for reactions requiring light sources of certain

  • photosensitized oxidation (chemistry)

    food preservation: Light-induced reactions: …carotenoid pigments (a process called photosensitized oxidation). The use of packaging material that prevents exposure to light is one of the most effective means of preventing light-induced chemical spoilage.

  • photosensor (instrument)

    fax: Standard fax transmission: …solid-state scanner that has 1,728 photosensors in a single row. Each photosensor in turn generates a low or high variation in voltage, depending on whether the scanned spot is black or white. Since there normally are 4 scan lines per mm (100 scan lines per inch), the scanning of a…

  • Photoshop (software)

    Adobe Photoshop, computer application software used to edit and manipulate digital images. Photoshop was developed in 1987 by the American brothers Thomas and John Knoll, who sold the distribution license to Adobe Systems Incorporated in 1988. Photoshop was originally conceived as a subset of the

  • Photoshop CS (software)

    Adobe Photoshop, computer application software used to edit and manipulate digital images. Photoshop was developed in 1987 by the American brothers Thomas and John Knoll, who sold the distribution license to Adobe Systems Incorporated in 1988. Photoshop was originally conceived as a subset of the

  • photosphere (astronomy)

    Photosphere, visible surface of the Sun, from which is emitted most of the Sun’s light that reaches Earth directly. Since the Sun is so far away, the edge of the photosphere appears sharp to the naked eye, but in reality the Sun has no surface, since it is too hot for matter to exist in anything

  • photosynthesis (biology)

    Photosynthesis, the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds. It would

  • photosynthetic organism (biology)

    bacteria: Phototrophic metabolism: Life on Earth is dependent on the conversion of solar energy to cellular energy by the process of photosynthesis. The general process of photosynthesis makes use of pigments called chlorophylls that absorb light energy from the Sun and release an electron with a…

  • photosynthetic reaction center (biochemistry)

    Robert Huber: …a protein complex (called a photosynthetic reaction centre) that is essential to photosynthesis in certain bacteria. By 1985 the three scientists had succeeded in describing the complete atomic structure of the protein. Although bacterial photosynthesis is somewhat simpler than that carried on by plants, the scientists’ work significantly increased the…

  • photosynthetic reaction centre (biochemistry)

    Robert Huber: …a protein complex (called a photosynthetic reaction centre) that is essential to photosynthesis in certain bacteria. By 1985 the three scientists had succeeded in describing the complete atomic structure of the protein. Although bacterial photosynthesis is somewhat simpler than that carried on by plants, the scientists’ work significantly increased the…

  • photosystem I (biology)

    bacteria: Phototrophic metabolism: The photosystem in green bacteria is related to photosystem I of higher plants, whereas that in purple bacteria is related to photosystem II, which provides some indication of an evolutionary trail from bacteria to plants (see photosynthesis: The process of photosynthesis: the light reactions).

  • photosystem II (biology)

    bacteria: Phototrophic metabolism: …purple bacteria is related to photosystem II, which provides some indication of an evolutionary trail from bacteria to plants (see photosynthesis: The process of photosynthesis: the light reactions).

  • phototaxis (biology)

    Volvox: …at one side to facilitate phototaxis (movement toward light) for photosynthesis, and the reproductive cells are grouped at the opposite side.

  • phototheodolite (measurement instrument)

    theodolite: The phototheodolite, a combination camera and theodolite mounted on the same tripod, is used in terrestrial photogrammetry for mapmaking and other purposes.

  • phototherapy (medicine)

    radiation: Phototherapy: Intense visible light is used in treating newborns’ jaundice, a disease characterized by the accumulation of the pigment bilirubin in the bloodstream during the first few days of life. Since wavelengths of 420–480 nanometres absorbed in the skin expedite detoxification and elimination of the…

  • photothermal device (technology)

    electromagnetic radiation: Visible radiation: In photothermal devices, sunlight is used to heat a substance, as, for example, water, to produce steam with which to drive a generator. Photovoltaic devices, on the other hand, convert the energy in sunlight directly to electricity by use of the photovoltaic effect in a semiconductor…

  • phototransmutation (physics)

    Photodisintegration, in physics, nuclear reaction in which the absorption of high-energy electromagnetic radiation (a gamma-ray photon) causes the absorbing nucleus to change to another species by ejecting a subatomic particle, such as a proton, neutron, or alpha particle. For example, m

  • phototroph (biology)

    bacteria: Phototrophic metabolism: Life on Earth is dependent on the conversion of solar energy to cellular energy by the process of photosynthesis. The general process of photosynthesis makes use of pigments called chlorophylls that absorb light energy from the Sun and release an electron with a…

  • phototrophy (biology)

    bacteria: Phototrophic metabolism: Life on Earth is dependent on the conversion of solar energy to cellular energy by the process of photosynthesis. The general process of photosynthesis makes use of pigments called chlorophylls that absorb light energy from the Sun and release an electron with a…

  • phototropism (biology)

    plant development: The emergence of the seedling: Light affects both the orientation of the seedling and its form. When a seed germinates below the soil surface, the plumule may emerge bent over, thus protecting its delicate tip, only to straighten out when exposed to light (the curvature is retained if the shoot…

  • phototube (electronics)

    Photoelectric cell, an electron tube with a photosensitive cathode that emits electrons when illuminated and an anode for collecting the emitted electrons. Various cathode materials are sensitive to specific spectral regions, such as ultraviolet, infrared, or visible light. The voltage between the

  • phototypesetting (printing)

    Photocomposition, method of assembling or setting type by photographing characters on film from which printing plates are made. The characters are developed as photographic positives on film or light-sensitive paper from a negative master containing all the characters; the film, carrying the

  • photovoltaic device (technology)

    thin-film solar cell: Applications of thin-film solar cells: …century the potential for thin-film applications increased greatly, because of their flexibility, which facilitates their installation on curved surfaces as well as their use in building-integrated photovoltaics.

  • photovoltaic effect (physics)

    Photovoltaic effect, process in which two dissimilar materials in close contact produce an electrical voltage when struck by light or other radiant energy. Light striking crystals such as silicon or germanium, in which electrons are usually not free to move from atom to atom within the crystal,

  • photovoltaic exposure meter (photography)

    exposure meter: …were of the self-generating, or photovoltaic, type, in which a selenium element converted the incoming light directly into an electric current. A microammeter measured this current and was calibrated to indicate the intensity of the light. Exposure was then set by adjusting dials to control aperture opening and shutter speed,…

  • photovoltaic panel (technology)

    satellite communication: How satellites work: …power system, which includes the solar panels that provide power, and the propulsion system, which includes the rockets that propel the satellite. A satellite needs its own propulsion system to get itself to the right orbital location and to make occasional corrections to that position. A satellite in geostationary orbit…

  • Photuris (insect genus)

    aggressive mimicry: …female fireflies of the genus Photuris. These insects imitate the mating flashes of the fireflies of the genus Photinus; the unlucky Photinus males deceived by the mimics are eaten. Another example is found in the brood parasitism practiced by the European cuckoo (Cuculus canorus). The eggs of this species closely…

  • Phoumi Vongvichit (Laotian politician)

    Phoumi Vongvichit, Laotian political leader (born April 6, 1909, French Indochina?—died Jan. 7, 1994), was a longtime communist and a leader in the Pathet Lao (Land of Lao) revolutionary movement against French colonial rule; he eventually became acting president (1986-91) of the Lao People’s De

  • Phoxinus eos (fish)

    dace: erythrogaster) and northern (P. eos) species. The southern redbelly dace, found in clear creeks from Alabama to Pennsylvania and the Great Lakes region, is an attractive fish sometimes kept in home aquariums. It is 5–7.5 cm (2–3 inches) long and is marked with two longitudinal black stripes.…

  • Phoxinus erythrogaster (fish)

    dace: …(Phoxinus) are well-known, with a southern (P. erythrogaster) and northern (P. eos) species. The southern redbelly dace, found in clear creeks from Alabama to Pennsylvania and the Great Lakes region, is an attractive fish sometimes kept in home aquariums. It is 5–7.5 cm (2–3 inches) long and is marked with…

  • Phoxinus phoxinus (fish)

    minnow: …Europe and northern Asia is Phoxinus phoxinus, a slim, small-scaled fish typical of clean streams and rivers. Also a member of the carp family, it is usually about 7.5 cm long. It varies in colour from golden to green, and the male, like certain other male cyprinids, develops a bright…

  • Phra Aphaimani (poem by Sunthon Phu)

    Southeast Asian arts: Second golden age: King Rama II (1809–24): …wrote his most famous poem, Phra Aphaimani, away from the court. A long fantasy-romance, this work can be regarded as the end of court domination in literature. Further, a royal official composed a Thai translation in prose (Sam Kok) of the Chinese classic Romance of the Three Kingdoms. The author,…

  • Phra Buddha Bat (temple, Sara Buri, Thailand)

    Sara Buri: The Phra Buddha Bat shrine in the town contains a footprint of Buddha and is the scene of a yearly festival. Sara Buri is linked to Bangkok, 60 miles (100 km) south-southwest, by rail and highway. Sara Buri is situated in a densely settled rice-growing and…

  • Phra Chedi Sam Ong (mountain pass, Myanmar-Thailand)

    Three Pagodas Pass, mountain pass in the Tenasserim Mountain Range on the Myanmar (Burma)-Thailand border, 100 miles (160 km) southeast of Moulmein, Myanmar. The pass, at an elevation of 925 feet (282 m), links southeastern Myanmar and western Thailand. For centuries it was the chief link between

  • Phra Malai (Buddhist monk)

    Buddhism: Kings and yogis: …Maha Moggallana’s successor, the monk Phra Malai, visited the Tushita Heaven to question the future buddha Maitreya concerning the time when he was to be reborn on earth in order to complete his buddha mission.

  • Phra Nakhon (section of Bangkok, Thailand)

    Phra Nakhon, section of Bangkok Metropolis, Thailand’s capital and largest city, on the east bank of the Mae Nam (river) Chao Phraya. It was a changwat (province) until 1972, when it was merged with Thon Buri, west of the river, to form the enlarged province of Krung Thep Mahanakhon (Bangkok

  • Phra Nakhon Si Ayutthaya (Thailand)

    Ayutthaya, town and former capital of the Tai state of Ayutthaya (Siam) located in central Thailand, about 55 miles (89 km) north of Bangkok. The site of immense temples and other structures that are important both historically and architecturally, Ayutthaya was added to UNESCO’s World Heritage

  • Your preference has been recorded
    Check out Britannica's new site for parents!
    Subscribe Today!