Encyclopedia

Periostat Periostat is a medication against advanced gum disease (chronic periodontitis), produced by CollaGenex Pharmaceuticals. The active compound is the antibiotic doxycycline, 20mg of which is contained in each tablet of Periostat.
Periosteal reaction Periosteal new bone formation ("periosteal reaction") can result from any of a large number of causes. The morphological appearance of periostitis (figure below) can be helpful, but is usually not sufficiently specific to determine its etiology.
Periostracum The periostracum is a thin organic coating forming the outer-most layer of the shell of many mollusks. The periostracum "is composed of a type of conchin [or conchiolin] (largely quinone-tanned proteins) similar to that found in the epidermal cuticle.
Perioxisomes Perioxisomes are organelles containing peroxide enzymes and perform many differentiating tasks, including breaking down fatty acids. Perioxisomes are found mainly in the liver and the kidneys, the organs primarily responsible for breaking down and excreting toxic chemicals.
Peripatetic The Peripatetics were members of a school of philosophy in ancient Greece. Their teachings derived from their founder, the Greek philosopher Aristotle and peripatetic (περιπατητικός) is a name given to his followers.
Peripatric speciation Peripatric speciation is a form of speciation, the formation of new species through evolution. In this form, new species are formed in isolated peripheral populations; this is similar to allopatric speciation in that populations are isolated and prevented from exchanging genes.
Peripatus Peripatus is a genus of Onychophora, which is distinguished by its independent pairs of legs, a characteristic which many entomologists believe suggests an evolutionary link between arthropods and worms. Peripatus is one of the group of animals known collectively as Velvet worms.
Peripheral A peripheral is a type of computer hardware that is added to a host computer in order to expand its abilities. More specifically, the term is used to describe those devices that are optional in nature, as opposed to hardware that is either demanded or always required in principle.
Peripheral blood cell Peripheral blood cells are the cellular components of blood, consisting of red blood cells, white blood cells, and platelets, which are found within the circulating pool of blood and not sequestered within the lymphatic system, spleen, liver, or bone marrow.
Peripheral consonant In Australian linguistics, the peripheral consonants are a natural class encompassing consonants articulated at the extremes of the mouth: bilabials and velars. In Australian languages, these consonants pattern together both phonotactically and acoustically.
Peripheral device In computer hardware, a peripheral device is any device attached to a computer in order to expand its functionality. Some of the more common peripheral devices are printers, scanners, disk drives, tape drives, microphones, speakers, and cameras.
Peripheral drift illusion The peripheral drift illusion (PDI) refers to a motion illusion generated by the presentation of a sawtooth luminance grating in the visual periphery. This illusion was first described by Faubert and Herbert (1999), although a similar effect called the "escalator illusion" was reported by Fraser and Wilcox (1979).
Peripheral giant cell granuloma Peripheral giant cell granuloma is an oral pathologic condition that appears in the mouth as an overgrowth of tissue due to irritation or trauma. Because of its overwhelming incidence on the gingiva, the condition is associated with two other diseases, though not because they occur together.
Peripheral chemoreceptor Peripheral chemoreceptors specialized cells located in the carotid and aortic bodies. They measure the conentration of various chemicals in the blood and convery this information to the brain to help regulate homeostasis.
Peripheral Interface Adapter The Peripheral Interface Adapter (PIA) is a peripheral integrated circuit providing parallel I/O interfacing capability for microprocessor systems. Common PIAs include the Motorola MC6820 and MC6821, and the MOS Technology MCS6520, all of which are functionally identical but have slightly different electrical characteristics.
Peripheral membrane protein Peripheral membrane proteins are proteins that adhere only temporarily to the biological membrane with which they are associated. These molecules attach to integral membrane proteins, or penetrate the peripheral regions of the lipid bilayer.
Peripheral nervous system The peripheral nervous system or PNS, is part of the nervous system, and consists of the nerves and neurons that reside or extend outside the central nervous system (the brain and spinal cord) to serve the limbs and organs, for example. Unlike the central nervous system, however, the PNS is not protected by bone or the blood-brain barrier, leaving it exposed to toxins and mechanical injuries.
Peripheral ossifying fibroma Peripheral ossifying fibroma is an oral pathologic condition that appears in the mouth as an overgrowth of gingival tissue due to irritation or trauma. Because of its overwhelming incidence on the gingiva, the condition is associated with two other diseases, though not because they occur together.
Peripheral vascular examination In medicine, the peripheral vascular examination is a series of maneuvers to elicit signs of peripheral vascular pathology. It is performed as part of a physical examination, or when a patient presents with leg pain suggestive of a cardiovascular pathology.
Peripheries of Greece The peripheries (περιφέρειες) are the official regional administrative divisions of Greece. There are 13 peripheries (nine on the mainland and four island groups), which are further subdivided into 54 prefectures.
Periphyton Periphyton is a complex matrix of algae, cyanobacteria, heterotrophic microbes, and detritus that is attached to submerged surfaces in most aquatic ecosystems. It serves as an important food source for invertebrates, tadpoles, and some fish.
Periplasmic space The periplasmic space is the space seen between the plasma membrane and the outer membrane in the gram-negative bacteria. A smaller periplasmic space between the plasma membrane and the peptidoglycan layer (cell wall) may be observed in the gram-positive bacteria.
Periplus A periplus (περίπλους, literally "a sailing-around' in Greek, roughly corresponding to the Latin navigatio, a "ship-voyage") in the ancient navigation of Phoenicians, Greeks, and Romans was a manuscript document that listed in order the ports and coastal landmarks, with approximate distances between, that the captain of a vessel could expect to find along a shore. Several examples of periploi have survived:
Periplus of the Erythraean Sea The Periplus of the Erythraean Sea (Periplus Maris Erythraei) is a Greek periplus, describing navigation and trading opportunities from Roman Egyptian ports like Berenice along the coast of the Red Sea, and others along East Africa and India. The text has been ascribed to different dates between the 1st and 3rd century CE, but a mid first century date is now the most commonly accepted.
Peripter Peripter, a special type of antique temples, which is surrounded on all four sides with a portico with column. It's very frequent in Corynthian and Doric order (Partenon and Tezeion in Athens; Apollo's temple in Selinunt on Sycilly: Temple of Zeus in Olympia etc.
Perique Perhaps the most strongly-flavored of all tobaccos is the Perique, from Saint James Parish, Louisiana. When the Acadians made their way into this region in 1776, the Choctaw and Chickasaw tribes were cultivating a variety of tobacco with a distinctive flavor.
Periscope A periscope is an instrument for observation from a concealed position. In its simplest form it is a tube in each end of which are mirrors set parallel to each other and at an angle of 45° with respect to the line between them.
Periscope antenna In telecommunication, a periscope antenna is an antenna configuration in which the transmitting antenna is oriented to produce a vertical radiation pattern, and a flat or off-axis parabolic reflector, mounted above the transmitting antenna, is used to direct the beam in a horizontal path toward the receiving antenna.
Periscope rifle A periscope rifle was first invented by Sergeant William Beech, a builders foreman, 2nd Battalion NSW, of the Royal Australian Army Corps in May, 1915. The weapon consisted of a standard rifle along with a board and mirror periscope, which looked along the sights of the rifle, fitted to it with a string based trigger pull allowing actuation of the trigger from beneath the line of sight of the firearm.
Perisher Blue, New South Wales Perisher Blue is Australia's largest skiing resort. It is located in the Australian Snowy Mountains in the southeastern corner of New South Wales, in the Snowy River Shire, about 600 kilometres southwest of Sydney.
Perisher Valley, New South Wales Perisher Valley () is a ski resort village in the Snowy Mountains of New South Wales, Australia, in the Snowy River Shire. It is primarily a winter only resort village, although all-year-round accommodation is available.
Perisoreus The genus Perisoreus is a very small genus of Jays from the Boreal regions of North America and Eurasia from Scandinavia to the Asian seaboard. An isolated species also occurs in north-western Szechuan province of China.
Perisphere The Trylon and the Perisphere were the central structures of the New York World's Fair of 1939-1940. Connected to the Trylon, which stood 600 feet tall, by the Helicline, at the time the world's longest escalator, the Perisphere was a tremendous sphere, 180 feet in diameter.
Peristaltic pump A peristaltic pump is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained within a flexible tube fitted inside a circular pump casing (though linear peristaltic pumps have been made).
Peristera Peristera (Greek: Περιστέρα, feminine form of pigeon), also Aspro, locally Xero (meaning dry) is a Greek island in the Sporades. It is administratively part of the municipality of Alonissos and is also directly east of the island of Alonissos.
Peristeri Peristeri (Greek: Περιστέρι, standing for "pigeon" in Greek), older forms Peristerio and Peristerion is a suburban municipality in Athens area (Attica), Greece. It is located about 5 km NW of the downtown area.
Peristeria (orchid) Peristeria is a genus of plants belonging to the family Orchidaceae whose genus' common name is the "Dove Orchid" or the "Holy Ghost Orchid". In line with the common name, the genus' name is from the Greek word peristerion meaning "from dove".
Peristimulus time histogram Peristimulus time histogram (also known as poststimulus time histogram and perievent time histogram) is a histogram that visualizes the instantaneous rate of neuronal spike discharges responding to an external stimulus or event.
Perisur Perisur (also Centro Comercial Perisur) is a shopping mall located in the Coyoacán borough in the south of Mexico City at the intersection of Insurgentes Avenue and Anillo Periférico, next to UNAM main Campus in Ciudad Universitaria and to the Jardines del Pedregal upscale nighborhood. It takes its name from being on the side of the south of Periférico (Perisur short for Periférico Sur)
Perito Moreno Glacier The Perito Moreno Glacier () is a glacier located in the Los Glaciares National Park in the south west of Santa Cruz province, Argentina. It is one of the most important tourist attractions in the Argentine Patagonia.
Peritomy A peritomy, or peritectomy, is a procedure carried out in eye surgery by ophthalmology, where a strip of the conjuctiva of an eye is removed, usually to correct pannus, where blood vessels begin to grow into the peripheral cornea. Definition of 'peritomy'
Peritoneal equilibration test In nephrology, the peritoneal equilibration test (PET), is a tool used by nephrologists to determine the characteristics of the peritoneal membrane mass transport characteristics, when assessing a patient for peritoneal dialysis.
Peritoneum In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdominal cavity - it covers most of the intra-abdominal organs. It is composed of layer of mesothelium supported by a thin layer of connective tissue.
Peritrich The peritrichs are a large and distinctive group of ciliate protozoa. They are usually bell or disc shaped, with a prominent paroral membrane arising from the oral cavity and circling counter-clockwise around the anterior of the cell, accompanied by a smaller series of membranelles.
Peritrope Peritrope was known for many centuries primarily as a tool for refuting ancient skepticism (in Sextus Empiricus, Avicenna, and Thomas Aquinas, for example). If I make the assertion, “There is no truth,” then you can respond using peritrope by posing the rhetorical question “Well, then, isn’t that true?
Peritus Peritus (from the Latin for Expert) is the title given to Roman Catholic theologians present to give advice at an Ecumenical council. At the most recent, the Second Vatican Council, some periti (the plural form) accompanied individual Bishops or groups of Bishops from various countries.
Periya Puranam Periya Puranam (that is, the Great Puranas) or Tiruttontarpuranam (that is, The Puranas of the Holy Devotees) is a great Tamil work, depicting the legendary poetic account of the lives and time of the sixty-three Nayanmars. It was complied during the 12th century by Sekkilar.
Perjury Perjury is the act of lying or making verifiably false statements on a material matter under oath or affirmation in a court of law or in any of various sworn statements in writing. Perjury is a crime because the witness has sworn to tell the truth and, for the credibility of the court, witness testimony must be relied on as being truthful.
Perkasie, Pennsylvania Perkasie is a borough in Bucks County, Pennsylvania, 35 miles (56 km) north of Philadelphia. Establishments in the borough early in the twentieth century included silk mills, baseballs, brickyards, lumber mills, tile works, a stone crusher, and manufacturies of cigars, tags and labels, wire novelties, etc.
Perkele Perkele is a god in the Finnish mythology equivalent of the God of Thunder, which was also referred to as "Ukko", meaning "an old man". The name is originally taken from Indo-European cultures.
Perkin Medal The Perkin Medal is an award given annually by the American section of the Society of Chemical Industry to a scientist residing in America for an "innovation in applied chemistry resulting in outstanding commercial development." It is considered the highest honor given in the US industrial chemical industry.
Perkin reaction The Perkin reaction is a chemical reaction developed by William Perkin that can be used to make cinnamic acids by the aldol condensation of aromatic aldehydes and acid anhydrides in the presence of an alkali salt of the acid.
Perkins Restaurant and Bakery Perkins Restaurant and Bakery is a North American casual dining restaurant chain. Known for serving breakfast throughout the day (much like their competitor Denny's), they also specialize in producing baked goods such as muffins and pies.
Perkins School for the Blind The Perkins School for the Blind is a learning center for people who are blind, deafblind, or have multiple disabilities. The school was founded by John Dix Fisher in 1829 as the "'New England Asylum for the Blind'", and currently located in Watertown, Massachusetts.
Perkinsus marinus Perkinsus marinus is a prevalent pathogen of oysters, causing massive mortality in oyster populations. The disease it causes is known as "Dermo", and is characterized by proteolytic degradation of oyster tissues.
Perkiomen Trail The Perkiomen Trail is a multi-use trail which begins at the junction with the Schuylkill River Trail extension to Valley Forge NHP and ends in Green Lane Park. It follows the Perkiomen Creek and connects Lower Perkiomen Valley Park, Central Perkiomen Valley Park, and Green Lane Parks.
Perkiomen Valley Academy Perkiomen Valley Academy Day Treatment Program, Incorporated (PVA) is one of five individual treatment and alternative educational centers for adolescents in Montgomery County, Pennsylvania. The program serves twelve to eighteen year old students from the eight school districts located in western Montgomery County.
Perkkaanpuiston Montessorikoulu Perkkaanpuiston Montessorikoulu (Finnish for "Perkkaanpuisto Montessori School") was Finland's first proper primary school using the Montessori method of teaching. Prior to the opening of the school, the Montessori method had only been used in preschools.
Perl 6 rules Perl 6 rules are Perl 6's regular expression, pattern matching and general-purpose parsing facility, and are a core part of the language. Since Perl's pattern-matching constructs have exceeded the capabilities of formal regular expressions for some time, Perl 6 documentation will exclusively refer to them as regexes, distancing the term from the formal definition.
Perl Compatible Regular Expression Perl Compatible Regular Expressions (PCRE) is a regular expression C library derived from Perl's external interface. PCRE is much richer than classic regular expression libraries which is why they have been adopted by many modern programming languages.
Perl Cookbook The Perl Cookbook, ISBN 0-596-00313-7, is a book containing solutions to common short tasks in Perl. Each chapter covers a particular topic area ("Strings", "Ties, Objects, and Classes", "CGI") and is divided into around a dozen recipes each on a particular problem ("Reversing A String By Word Or Character", "Accessing Overridden Methods", "Managing Cookies").
Perl DBI Perl DBI (DataBase Interface) is the most common database interface for the Perl programming language. DBI was specified by Tim Bunce, in collaboration with others, starting in 1994, and is currently maintained across the Internet as a CPAN module in accordance with the Open Source model.
Perl Object-Oriented Persistence Perl Object-Oriented Persistence (POOP) is the term given to refer to object-relational mapping mechanisms written in the Perl programming language to provide object persistence. Dave Rolsky divides POOP mechanisms into two categories:
Perl package manager Perl Package Manager (PPM) is a Perl utility intended to simplify the tasks of locating, installing, upgrading and removing software packages. It can determine if the most recent version of a software package is installed on a system, and can install or upgrade that package from a local or remote host.
Perlecan Perlecan is a large multidomain proteoglycan that binds to and cross-links many extracellular matrix (ECM) components and cell-surface molecules. Perlecan is synthesized by both vascular endothelial and smooth muscle cells and deposited in the extracellular matrix.
Perlesvaus Perlesvaus, also called Li Hauz Livres du Graal (The High History of the Holy Grail), is an Old French Arthurian romance dating to the first decade of the 13th century. It purports to be a continuation of Chrétien de Troyes unfinished Perceval, the Story of the Grail, but it has been called the least canonical Arthurian tale because of its striking differences from other versions.
Perlin The word perlin is a falconer's term for a hybrid between a peregrine falcon and a merlin. It is bigger and faster than a merlin, but does not fly as far as a peregrine, and thus is less likely to fly far away and become lost.
Perlis Plantations Bhd PPB Group Berhad is a diversified company which was incorporated in November 1968, and its business beginning with cultivate sugar cane and to extract, process and market sugar. In May 1972, PPB was listed both stock exchnage in Kuala Lumpur and Singapore with an issued and paid-up capital of RM15.
Perlla Perla Fernandes dos Santos (born November 28, 1988, in Rio de Janeiro, Brazil) is a teenage Brazilian Dance music and Pop singer commonly known by Perlla. She rose to fame with her first album, Eu SĂł Quero Ser Livre, in early-2006.
Perlo group Headed by Victor Perlo, the Perlo group is the name given to a group of people who provided information which was given to Soviet intelligence agencies; it was active during the World War II period, until the entire group was exposed to the FBI by the defection of Elizabeth Bentley.
Perlon Perlon is an electronic music record label founded in Frankfurt, Germany and based in Berlin by Zip and Markus Nikolai. It can be clasiffied in the minimal way of techno and his sound is very particulary with some perfect arranged vocals and crispy sounds.
PerlScript PerlScript is an ActiveX Scripting Engine produced by the company ActiveState. It can be used by programmers in addition to, or in place of, VBScript or JScript in the context of web servers running the ASP protocol.
Perlur og svĂ­n Perlur og svĂ­n (meaning "Pearls and pigs", referring to an Icelandic expression) is the fifth studio album of Icelandic band Todmobile. After releasing Spillt in 1993, the band disbanded, but Ăžorvaldur and Andrea continued to work together on the light pop band Tweety.
Perm Krai Perm Krai () is a federal subject of Russia (a krai) that came into existence on December 1, 2005 as a result of the 2004 referendum on the merger of Perm Oblast and Komi-Permyak Autonomous Okrug. The city of Perm became the administrative center of the new federal subject.
Perm Oblast Until December 1, 2005, Perm Oblast () was a federal subject of Russia (an oblast) in Privolzhsky (Volga) Federal District. According to the results of the referendum held in October of 2004, Perm Oblast was merged with Komi-Permyak Autonomous Okrug to form Perm Krai.
Permafrost In geology, permafrost or permafrost soil is ground that stays at or below the freezing point of water (0°C or 32°F) for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of the ground material.
Permal Permal Group, one of the oldest funds of hedge funds, is headquartered in London, with offices in New York, Boston, Singapore, Paris, Nassau, Dubai and Hong Kong. It manages approximately $30 billion in assets and employs over 140 people including 4 senior managers and 16 investment managers/analysts.
Permanent (album) Permanent is a compilation by Joy Division, featuring tracks from the band's two studio albums, Unknown Pleasures and Closer, as well as other tracks previously released on the compilations Substance and Still. The one new track is a new mix of "Love Will Tear Us Apart" entitled Permanent mix.
Permanent Autonomous Zone A Permanent autonomous zone (or a PAZ) is a community that is autonomous from the generally recognized government or authority structure in which it is embedded. PAZs are not controlled by any government (as recognized by other governments) or by any religious authority.
Permanent Committee The Permanent Committee for Islamic Research and Fataawa (in Arabic, al-Lajnah ad-Daa'imah lil-Buhooth al-'Ilmiyyah wal-Iftaa) is an Islamic organization in Saudi Arabia that issues rulings in Islamic jurisprudence (fiqh). It consists of the most senior Sunni scholars of fiqh in Saudi Arabia.
Permanent Council The Permanent Council (Polish Rada NieustajÄ…ca) was the highest administrative authority in the Polish-Lithuanian Commonwealth between 1775 and 1789 and the first modern government in Europe. In Polish was renamed as Zdrada NieustajÄ…ca - Permanent Betrayal.
Permanent Court of Arbitration The Permanent Court of Arbitration (PCA), also known as the Hague Tribunal is an international organization based in The Hague in the Netherlands. It was established in 1899 as one of the acts of the first Hague Peace Conference, which makes it the oldest institution for international dispute resolution.
Permanent Court of International Justice The Permanent Court of International Justice, sometimes called World Court, was the international court of the League of Nations established in 1922. Between 1922 and 1940 the Court dealt with 29 contentious cases between States and delivered 27 advisory opinions.
Permanent death In computer role-playing games, permanent death (sometimes permadeath or PD) is a term for a situation in games in which player characters (PCs) die permanently and are removed from the game. This is in contrast to games in which characters who are killed (or incapacitated) can be restored to life (or full health), at some minor cost to the character.
Permanent establishment The concept of permanent establishment ("PE") is one of the most important issues in international tax treaty law. Virtually all modern tax treaties use PE as the main instrument to establish taxing jurisdiction over a foreigner's unincorporated business activities.
Permanent Fatal Error Permanent Fatal Error (PFE) is a new musical project by Olivier Manchion, Ulan Bator founder member, and long time Faust collaborator. PFE first album is entitled Law Speed and was released in 2004 by Wallace Records, Ruminance, Klangbad.
Permanent Force The Permanent Force was an integral part of both the South African Defence Force and the South West Africa Territorial Force and other British Commonwealth militaries. It consisted of all the full time volunteers, volunteers of auxiliaries and national servicemen.
Permanent guest host Permanent guest host is an oxymoron that likely originated on The Tonight Show Starring Johnny Carson. It is believed that Penn and Teller were the first to declare the phrase to be a "rare triple oxymoron.
Permanent hiatus The term permanent hiatus refers to a television show or video game that work has been stopped on, often titles which find themselves on permanent hiatus are dangerously close to being cancelled. It should be noted however that a hiatus itself does not mean a show is being cancelled, often in US Television a network may put a show on Hiatus to air another show in its timeslot, or for continuty reasons a show will make its initial run shorter.
Permanent income hypothesis The permanent income hypothesis (PIH) was developed by the American economist Milton Friedman. In its simplest form, PIH states that the choices made by a consumer regarding their consumption patterns are determined not by current income but by their longer-term income expectations.
Permanent Interstate Committee for drought control in the Sahel The permanent Interstate Committee for drought control in the Sahel (French: Comité permanent inter-État de lutte contre la sécheresse au Sahel , abbreviated as CILSS) is an international organization of countries in the Sahel.
Permanent Joint Board of Defense The Permanent Joint Board on Defence was established by Canada and the United States on August 17, 1940 by joint announcement of President Franklin D. Roosevelt and Prime Minister William Lyon Mackenzie King at Ogdensburg, New York.
Permanent life insurance Permanent life insurance is a form of life insurance such as whole life or endowment, where the policy is for the life of the insured, the payout is assured at the end of the policy (assuming the policy is kept current) and the policy accrues cash value.
Permanent makeup Permanent makeup is a cosmetic technique which employs tattoos (permanent pigmentation of the dermis) as a means of producing designs that resemble makeup, such as eyelining (eye shadows) and other permanent enhancing colors to the skin of the face, lips and eyelids. It is also used to produce artificial eyebrows, particularly in people who have lost it as a consequence of old age, disease, such as alopecia, chemotherapy or a genetic disturbance, and to disguise scars and white spots in the skin such as in vitiligo.
Permanent marker A permanent marker is a type of marker pen that is used to create permanent writing on an object. Generally the ink is water resistant, contains the toxic chemical xylene or toluene, and is capable of writing on a variety of surfaces from paper to metal to stone.
Permanent Midnight Permanent Midnight is a 1998 movie directed by David Veloz starring Ben Stiller. The film is based on Jerry Stahl's autobiographical book of the same name, and tells the story of Stahl's rise from a small-time television writer to his success as a comedy writer making up to $5,000 a week writing for 1980s shows like thirtysomething, Moonlighting, and probably most infamously, ALF (changed in the movie to Mr.
Permanent press A permanent press is a fabric that has been chemically processed with methanol to resist wrinkles and hold its shape. Treating fabric with the simplest form of alcohol (methanol) has a lasting effect on the fabric.
Permanent Private Hall A Permanent Private Hall at the University of Oxford is an educational institution affiliated to the University — not as a full College, but able to present students for Oxford University degrees. "PPHs" are usually, though not necessarily, small foundations of a religious character; thus many offer a limited number of degrees, sometimes only to members of a specific religious order, and generally in Theology and related subjects.
Permanent resident (Canada) A Permanent Resident in Canada is someone who is not a Canadian citizen and who has been granted permission to live and work in Canada without any time limit on his or her stay. A permanent resident must live in Canada for two years of every five years or risk losing that status.
Permanent revolution Permanent Revolution is a term within Marxist theory, which was first used by Karl Marx and Friedrich Engels between 1845 and 1850, but has since become most closely associated with Leon Trotsky, and other Bolsheviks. The use of the term by the theorists is not identical.

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