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25203 | https://en.wikipedia.org/wiki/Quilting | Quilting | Quilting is the process of joining a minimum of three layers of fabric together either through stitching manually using a needle and thread, or mechanically with a sewing machine or specialised longarm quilting system. An array of stitches is passed through all layers of the fabric to create a three-dimensional padded ... | Technology | Techniques_2 | null |
25211 | https://en.wikipedia.org/wiki/Quantum%20chemistry | Quantum chemistry | Quantum chemistry, also called molecular quantum mechanics, is a branch of physical chemistry focused on the application of quantum mechanics to chemical systems, particularly towards the quantum-mechanical calculation of electronic contributions to physical and chemical properties of molecules, materials, and solution... | Physical sciences | Chemistry: General | null |
25213 | https://en.wikipedia.org/wiki/QWERTY | QWERTY | QWERTY ( ) is a keyboard layout for Latin-script alphabets. The name comes from the order of the first six keys on the top letter row of the keyboard: . The QWERTY design is based on a layout included in the Sholes and Glidden typewriter sold via E. Remington and Sons from 1874. QWERTY became popular with the success o... | Technology | Media and communication: Basics | null |
25220 | https://en.wikipedia.org/wiki/Quantum%20computing | Quantum computing | A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of both particles and waves, and quantum computing leverages this behavior using specialized hardware. Classical physics cannot explain the operation of these quantum devices, and a scalable... | Technology | Computer architecture concepts | null |
25229 | https://en.wikipedia.org/wiki/Quagga | Quagga | The quagga ( or ) (Equus quagga quagga) is an extinct subspecies of the plains zebra that was endemic to South Africa until it was hunted to extinction in the late 19th century. It was long thought to be a distinct species, but MtDNA studies have supported it being a subspecies of plains zebra. A more recent study sugg... | Biology and health sciences | Equidae | Animals |
25233 | https://en.wikipedia.org/wiki/Quartz | Quartz | Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is, therefore, classified structurally as a framework sil... | Physical sciences | Mineralogy | null |
25236 | https://en.wikipedia.org/wiki/Quadrupedalism | Quadrupedalism | Quadrupedalism is a form of locomotion where animals have four legs that are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four legs is said to be a quadruped (from Latin quattuor for "four", and pes, pedis for "foot"). Quadruped animals are f... | Biology and health sciences | Ethology | Biology |
25239 | https://en.wikipedia.org/wiki/Quasar | Quasar | A quasar ( ) is an extremely luminous active galactic nucleus (AGN). It is sometimes known as a quasi-stellar object, abbreviated QSO. The emission from an AGN is powered by accretion onto a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion ... | Physical sciences | Active galactic nucleus | null |
25247 | https://en.wikipedia.org/wiki/Quill | Quill | A quill is a writing tool made from a moulted flight feather (preferably a primary wing-feather) of a large bird. Quills were used for writing with ink before the invention of the dip pen/metal-nibbed pen, the fountain pen, and, eventually, the ballpoint pen.
As with the earlier reed pen (and later dip pen), a quill h... | Technology | Writing tools | null |
25264 | https://en.wikipedia.org/wiki/Quantum%20chromodynamics | Quantum chromodynamics | In theoretical physics, quantum chromodynamics (QCD) is the study of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a type of quantum field theory called a non-abelian gauge theory, with symmetry grou... | Physical sciences | Quantum mechanics | null |
25265 | https://en.wikipedia.org/wiki/Queue%20%28abstract%20data%20type%29 | Queue (abstract data type) | In computer science, a queue is a collection of entities that are maintained in a sequence and can be modified by the addition of entities at one end of the sequence and the removal of entities from the other end of the sequence. By convention, the end of the sequence at which elements are added is called the back, tai... | Mathematics | Data structures and types | null |
25267 | https://en.wikipedia.org/wiki/Quantum%20field%20theory | Quantum field theory | In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and in condensed matter physics to construct models of quasipa... | Physical sciences | Quantum mechanics | null |
25268 | https://en.wikipedia.org/wiki/Quantum%20electrodynamics | Quantum electrodynamics | In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and special relativity is achieved. QED mathematically describes all phenomena inv... | Physical sciences | Quantum mechanics | null |
25272 | https://en.wikipedia.org/wiki/Quadratic%20reciprocity | Quadratic reciprocity | In number theory, the law of quadratic reciprocity is a theorem about modular arithmetic that gives conditions for the solvability of quadratic equations modulo prime numbers. Due to its subtlety, it has many formulations, but the most standard statement is:
This law, together with its supplements, allows the easy ca... | Mathematics | Modular arithmetic | null |
25278 | https://en.wikipedia.org/wiki/Quadrilateral | Quadrilateral | In geometry a quadrilateral is a four-sided polygon, having four edges (sides) and four corners (vertices). The word is derived from the Latin words quadri, a variant of four, and latus, meaning "side". It is also called a tetragon, derived from Greek "tetra" meaning "four" and "gon" meaning "corner" or "angle", in a... | Mathematics | Geometry | null |
25284 | https://en.wikipedia.org/wiki/Qubit | Qubit | In quantum computing, a qubit () or quantum bit is a basic unit of quantum information—the quantum version of the classic binary bit physically realized with a two-state device. A qubit is a two-state (or two-level) quantum-mechanical system, one of the simplest quantum systems displaying the peculiarity of quantum mec... | Physical sciences | Information | Basics and measurement |
25295 | https://en.wikipedia.org/wiki/Quiver | Quiver | A quiver is a container for holding arrows or bolts. It can be carried on an archer's body, the bow, or the ground, depending on the type of shooting and the archer's personal preference. Quivers were traditionally made of leather, wood, furs, and other natural materials, but are now often made of metal or plastic.
Et... | Technology | Archery | null |
25297 | https://en.wikipedia.org/wiki/Quinine | Quinine | Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to Plasmodium falciparum that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg cramps, quinine is not recommended for this purpose due to the risk of serious side ... | Biology and health sciences | Drugs and pharmacology | null |
25312 | https://en.wikipedia.org/wiki/Quantum%20gravity | Quantum gravity | Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics. It deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the vicinity of black holes or similar compact astrophysical objects, as well a... | Physical sciences | Basics_6 | null |
25319 | https://en.wikipedia.org/wiki/Quetzalcoatlus | Quetzalcoatlus | Quetzalcoatlus () is a genus of azhdarchid pterosaur that lived during the Maastrichtian age of the Late Cretaceous in North America. The type specimen, recovered in 1971 from the Javelina Formation of Texas, United States, consists of several wing fragments and was described as Quetzalcoatlus northropi in 1975 by Doug... | Biology and health sciences | Pterosaurs | Animals |
25336 | https://en.wikipedia.org/wiki/Quantum%20entanglement | Quantum entanglement | Quantum entanglement is the phenomenon of a group of particles being generated, interacting, or sharing spatial proximity in such a way that the quantum state of each particle of the group cannot be described independently of the state of the others, including when the particles are separated by a large distance. The t... | Physical sciences | Quantum mechanics | null |
25409 | https://en.wikipedia.org/wiki/Reptile | Reptile | Reptiles, as commonly defined, are a group of tetrapods with an ectothermic ('cold-blooded') metabolism and amniotic development. Living traditional reptiles comprise four orders: Testudines (turtles), Crocodilia (crocodilians), Squamata (lizards and snakes), and Rhynchocephalia (the tuatara). As of May 2023, about 12,... | Biology and health sciences | Biology | null |
25418 | https://en.wikipedia.org/wiki/Proof%20by%20contradiction | Proof by contradiction | In logic, proof by contradiction is a form of proof that establishes the truth or the validity of a proposition by showing that assuming the proposition to be false leads to a contradiction.
Although it is quite freely used in mathematical proofs, not every school of mathematical thought accepts this kind of nonconstru... | Mathematics | Mathematical logic | null |
25453 | https://en.wikipedia.org/wiki/Rheology | Rheology | Rheology (; ) is the study of the flow of matter, primarily in a fluid (liquid or gas) state but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force. Rheology is the branch of physics that deals with the deformation a... | Physical sciences | Fluid mechanics | Physics |
25456 | https://en.wikipedia.org/wiki/Rifle | Rifle | A rifle is a long-barreled firearm designed for accurate shooting and higher stopping power, with a barrel that has a helical or spiralling pattern of grooves (rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with both hands and braced firmly against the... | Technology | Projectile weapons | null |
25484 | https://en.wikipedia.org/wiki/Rosemary | Rosemary | Salvia rosmarinus (), commonly known as rosemary, is a shrub with fragrant, evergreen, needle-like leaves and white, pink, purple, or blue flowers. It is native to the Mediterranean region, as well as Portugal and Spain. Until 2017, it was known by the scientific name Rosmarinus officinalis (), now a synonym.
It is a ... | Biology and health sciences | Herbs and spices | Plants |
25486 | https://en.wikipedia.org/wiki/Rosales | Rosales | Rosales (, ) are an order of flowering plants. Well-known members of Rosales include: roses, strawberries, blackberries and raspberries, apples and pears, plums, peaches and apricots, almonds, rowan and hawthorn, jujube, elms, banyans, figs, mulberries, breadfruit, nettles, hops, and cannabis.
Rosales contain about 7,... | Biology and health sciences | Rosales | Plants |
25524 | https://en.wikipedia.org/wiki/Research | Research | Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization, and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness to controlling sources of bias and error. These activities are characterized by a... | Physical sciences | Basics | null |
25599 | https://en.wikipedia.org/wiki/Rubidium | Rubidium | Rubidium is a chemical element; it has symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher than water. On Earth, natural rubidium comprises two isotopes: 72% is a stabl... | Physical sciences | Chemical elements_2 | null |
25600 | https://en.wikipedia.org/wiki/Ruthenium | Ruthenium | Ruthenium is a chemical element; it has symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is unreactive to most chemicals. Karl Ernst Claus, a Russian scientist of Baltic-German ancestry, discovered... | Physical sciences | Chemical elements_2 | null |
25601 | https://en.wikipedia.org/wiki/Rhodium | Rhodium | Rhodium is a chemical element; it has symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isotope, which is 103Rh. Naturally occurring rhodium is usually found as a free ... | Physical sciences | Chemical elements_2 | null |
25602 | https://en.wikipedia.org/wiki/Radium | Radium | Radium is a chemical element; it has symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather than oxygen) upon exposure to air, forming a black surface layer of radium nit... | Physical sciences | Chemical elements_2 | null |
25603 | https://en.wikipedia.org/wiki/Rhenium | Rhenium | Rhenium is a chemical element; it has symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. It has one of the highest melti... | Physical sciences | Chemical elements_2 | null |
25604 | https://en.wikipedia.org/wiki/Radon | Radon | Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only Rn has a sufficiently long half-life (3.825 days) for it to be released from the soil and rock where it is generated. Radon isotopes are ... | Physical sciences | Chemical elements_2 | null |
25657 | https://en.wikipedia.org/wiki/Roman%20numerals | Roman numerals | Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, each with a fixed integer value. The modern style uses only these seven:
The use ... | Mathematics | Basics | null |
25665 | https://en.wikipedia.org/wiki/Rosaceae | Rosaceae | Rosaceae (), the rose family, is a family of flowering plants that includes 4,828 known species in 91 genera.
The name is derived from the type genus Rosa. The family includes herbs, shrubs, and trees. Most species are deciduous, but some are evergreen. They have a worldwide range but are most diverse in the Northern ... | Biology and health sciences | Rosales | null |
25676 | https://en.wikipedia.org/wiki/Radar | Radar | Radar is a system that uses radio waves to determine the distance (ranging), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and... | Technology | Navigation and timekeeping | null |
25685 | https://en.wikipedia.org/wiki/Random%20variable | Random variable | A random variable (also called random quantity, aleatory variable, or stochastic variable) is a mathematical formalization of a quantity or object which depends on random events. The term 'random variable' in its mathematical definition refers to neither randomness nor variability but instead is a mathematical functio... | Mathematics | Statistics and probability | null |
25715 | https://en.wikipedia.org/wiki/Rail%20transport | Rail transport | Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in tracks, which usually consist of two parallel steel rails. Rail transport is one of the two primary means of land transport, next to road transport. It is used for about 8% of passenger and freight transport global... | Technology | Trains | null |
25717 | https://en.wikipedia.org/wiki/Regular%20expression | Regular expression | A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. Regular ex... | Technology | Software development: General | null |
25748 | https://en.wikipedia.org/wiki/Router%20%28computing%29 | Router (computing) | A router is a computer and networking device that forwards data packets between computer networks, including internetworks such as the global Internet.
A router is connected to two or more data lines from different IP networks. When a data packet comes in on a line, the router reads the network address information in ... | Technology | Networks | null |
25750 | https://en.wikipedia.org/wiki/Routing | Routing | Routing is the process of selecting a path for traffic in a network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched telephone network (PSTN), and computer networks, such as the Internet.
In packet switchin... | Technology | Networks | null |
25754 | https://en.wikipedia.org/wiki/Resistor | Resistor | A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistor... | Technology | Components | null |
25756 | https://en.wikipedia.org/wiki/Repetitive%20strain%20injury | Repetitive strain injury | A repetitive strain injury (RSI) is an injury to part of the musculoskeletal or nervous system caused by repetitive use, vibrations, compression or long periods in a fixed position. Other common names include repetitive stress injury, repetitive stress disorders, cumulative trauma disorders (CTDs), and overuse syndrome... | Biology and health sciences | Types | Health |
25758 | https://en.wikipedia.org/wiki/RNA | RNA | Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyribonucleic acid (DNA) are nucleic acids. The nucleic acids constitute one of th... | Biology and health sciences | Chemistry | null |
25766 | https://en.wikipedia.org/wiki/Ribosome | Ribosome | Ribosomes () are macromolecular machines, found within all cells, that perform biological protein synthesis (messenger RNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA molecules to form polypeptide chains. Ribosomes consist of two major components: the small an... | Biology and health sciences | Organelles and other cell parts | null |
25767 | https://en.wikipedia.org/wiki/Real-time%20computing | Real-time computing | Real-time computing (RTC) is the computer science term for hardware and software systems subject to a "real-time constraint", for example from event to system response. Real-time programs must guarantee response within specified time constraints, often referred to as "deadlines".
The term "real-time" is also used in s... | Technology | Computer science | null |
25768 | https://en.wikipedia.org/wiki/Ruby%20%28programming%20language%29 | Ruby (programming language) | Ruby is an interpreted, high-level, general-purpose programming language. It was designed with an emphasis on programming productivity and simplicity. In Ruby, everything is an object, including primitive data types. It was developed in the mid-1990s by Yukihiro "Matz" Matsumoto in Japan.
Ruby is dynamically typed and... | Technology | Scripting languages | null |
25781 | https://en.wikipedia.org/wiki/Robot | Robot | A robot is a machine—especially one programmable by a computer—capable of carrying out a complex series of actions automatically. A robot can be guided by an external control device, or the control may be embedded within. Robots may be constructed to evoke human form, but most robots are task-performing machines, desig... | Technology | Basics_8 | null |
25784 | https://en.wikipedia.org/wiki/Renewable%20energy | Renewable energy | Renewable energy (also called green energy) is energy from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, and hydropower. Bioenergy and geothermal power are also significant in some countries. Some also consider nuclear po... | Technology | Energy | null |
25794 | https://en.wikipedia.org/wiki/Revolver | Revolver | A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold up to six cartridges, before needing to be reloaded, revolvers are commonly called six shooters or sixguns. Due to their rotati... | Technology | Firearms | null |
25809 | https://en.wikipedia.org/wiki/Riemann%20zeta%20function | Riemann zeta function | The Riemann zeta function or Euler–Riemann zeta function, denoted by the Greek letter (zeta), is a mathematical function of a complex variable defined as for and its analytic continuation elsewhere.
The Riemann zeta function plays a pivotal role in analytic number theory and has applications in physics, probability... | Mathematics | Specific functions | null |
25825 | https://en.wikipedia.org/wiki/Red | Red | Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondary color (made from magenta and yellow) in the CMYK color model, and is the comple... | Physical sciences | Color terms | null |
25852 | https://en.wikipedia.org/wiki/Rice%27s%20theorem | Rice's theorem | In computability theory, Rice's theorem states that all non-trivial semantic properties of programs are undecidable. A semantic property is one about the program's behavior (for instance, "does the program terminate for all inputs?"), unlike a syntactic property (for instance, "does the program contain an if-then-else ... | Mathematics | Computability theory | null |
25856 | https://en.wikipedia.org/wiki/Radiation | Radiation | In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes:
electromagnetic radiation consisting of photons, such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ)
particle radiatio... | Physical sciences | Basics_6 | null |
25875 | https://en.wikipedia.org/wiki/Rheumatoid%20arthritis | Rheumatoid arthritis | Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involved, with the same joints typically involved on both sides of the body. The d... | Biology and health sciences | Specific diseases | Health |
25880 | https://en.wikipedia.org/wiki/Refractive%20index | Refractive index | In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refracted, when entering a material. This is described by Snell's law of refracti... | Physical sciences | Optics | null |
25897 | https://en.wikipedia.org/wiki/Road | Road | A road is a thoroughfare for the conveyance of traffic that mostly has an improved surface for use by vehicles (motorized and non-motorized) and pedestrians. Unlike streets, whose primary function is to serve as public spaces, the main function of roads is transportation.
There are many types of roads, including parkw... | Technology | Transportation | null |
25898 | https://en.wikipedia.org/wiki/Roman%20roads | Roman roads | Roman roads ( ; singular: ; meaning "Roman way") were physical infrastructure vital to the maintenance and development of the Roman state, built from about 300 BC through the expansion and consolidation of the Roman Republic and the Roman Empire. They provided efficient means for the overland movement of armies, offic... | Technology | Ground transportation networks | null |
25919 | https://en.wikipedia.org/wiki/Rapids | Rapids | Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Flow, gradient, constriction, and obstacles are four factors that are needed for a rapid to be created.
Physical factors
Rapids are hydrological features between a run (a smoothly ... | Physical sciences | Fluvial landforms | null |
25927 | https://en.wikipedia.org/wiki/Rutherfordium | Rutherfordium | Rutherfordium is a synthetic chemical element; it has symbol Rf and atomic number 104. It is named after physicist Ernest Rutherford. As a synthetic element, it is not found in nature and can only be made in a particle accelerator. It is radioactive; the most stable known isotope, 267Rf, has a half-life of about 48 min... | Physical sciences | Group 4 | Chemistry |
25948 | https://en.wikipedia.org/wiki/Refraction | Refraction | In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and water waves also experience refract... | Physical sciences | Optics | null |
25949 | https://en.wikipedia.org/wiki/Recreational%20drug%20use | Recreational drug use | Recreational drug use is the use of one or more psychoactive drugs to induce an altered state of consciousness, either for pleasure or for some other casual purpose or pastime. When a psychoactive drug enters the user's body, it induces an intoxicating effect. Recreational drugs are commonly divided into three categori... | Biology and health sciences | Drugs and pharmacology | null |
25977 | https://en.wikipedia.org/wiki/Ideal%20%28ring%20theory%29 | Ideal (ring theory) | In mathematics, and more specifically in ring theory, an ideal of a ring is a special subset of its elements. Ideals generalize certain subsets of the integers, such as the even numbers or the multiples of 3. Addition and subtraction of even numbers preserves evenness, and multiplying an even number by any integer (eve... | Mathematics | Abstract algebra | null |
25987 | https://en.wikipedia.org/wiki/Rickets | Rickets | Rickets, scientific nomenclature: rachitis (from Greek , meaning 'in or of the spine'), is a condition that results in weak or soft bones in children and may have either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications may... | Biology and health sciences | Health and fitness: General | Health |
25989 | https://en.wikipedia.org/wiki/RGB%20color%20model | RGB color model | The RGB color model is an additive color model in which the red, green, and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue.
The main purpose of the RGB color m... | Physical sciences | Basics_7 | null |
25995 | https://en.wikipedia.org/wiki/Reciprocating%20engine | Reciprocating engine | A reciprocating engine, more often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common features of all types. The main types are: the internal combustion engine, used exte... | Technology | Engines | null |
26003 | https://en.wikipedia.org/wiki/Radian | Radian | The radian, denoted by the symbol rad, is the unit of angle in the International System of Units (SI) and is the standard unit of angular measure used in many areas of mathematics. It is defined such that one radian is the angle subtended at the centre of a circle by an arc that is equal in length to the radius. The un... | Physical sciences | Angle | null |
26073 | https://en.wikipedia.org/wiki/Right%20ascension | Right ascension | Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the Earth.<ref
></ref>
When paired with declination, these astronomical coordinates specify the loc... | Physical sciences | Celestial sphere: General | Astronomy |
26088 | https://en.wikipedia.org/wiki/Red%20wolf | Red wolf | The red wolf (Canis rufus) is a canine native to the southeastern United States. Its size is intermediate between the coyote (Canis latrans) and gray wolf (Canis lupus).
The red wolf's taxonomic classification as being a separate species has been contentious for nearly a century, being classified either as a subspecie... | Biology and health sciences | Canines | Animals |
26118 | https://en.wikipedia.org/wiki/Roof | Roof | A roof (: roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temperature, and wind. A roof is part of the building envelope.
The characteristics... | Technology | Architectural elements | null |
26123 | https://en.wikipedia.org/wiki/Real-time%20operating%20system | Real-time operating system | A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. An RTOS is distinct from a time-sharing operating system, such as Unix, which manages the sharing of system resources with a scheduler, data ... | Technology | Operating systems | null |
26132 | https://en.wikipedia.org/wiki/Rankine%20scale | Rankine scale | The Rankine scale ( ) is an absolute scale of thermodynamic temperature named after the University of Glasgow engineer and physicist Macquorn Rankine, who proposed it in 1859.
History
Similar to the Kelvin scale, which was first proposed in 1848, zero on the Rankine scale is absolute zero, but a temperature differenc... | Physical sciences | Temperature | Basics and measurement |
26176 | https://en.wikipedia.org/wiki/Rayleigh%20scattering | Rayleigh scattering | Rayleigh scattering ( ) is the scattering or deflection of light, or other electromagnetic radiation, by particles with a size much smaller than the wavelength of the radiation. For light frequencies well below the resonance frequency of the scattering medium (normal dispersion regime), the amount of scattering is inve... | Physical sciences | Optics | Physics |
26194 | https://en.wikipedia.org/wiki/Restriction%20enzyme | Restriction enzyme | A restriction enzyme, restriction endonuclease, REase, ENase or restrictase is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction sites. Restriction enzymes are one class of the broader endonuclease group of enzymes. Restriction enzymes are commonly ... | Biology and health sciences | Molecular biology | Biology |
26214 | https://en.wikipedia.org/wiki/Reverse%20transcriptase | Reverse transcriptase | A reverse transcriptase (RT) is an enzyme used to convert RNA genome to DNA, a process termed reverse transcription. Reverse transcriptases are used by viruses such as HIV, COVID-19, and hepatitis B to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, and by euk... | Biology and health sciences | Molecular biology | Biology |
26229 | https://en.wikipedia.org/wiki/Riboflavin | Riboflavin | Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in energy metabolism, cellular respiration, and antibody production, as well as ... | Biology and health sciences | Vitamins | Health |
26262 | https://en.wikipedia.org/wiki/Redshift | Redshift | In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift, or negative redshift. The terms derive from t... | Physical sciences | Physical cosmology | null |
26286 | https://en.wikipedia.org/wiki/Rocket-propelled%20grenade | Rocket-propelled grenade | A rocket-propelled grenade (RPG) is a shoulder-fired rocket weapon that launches rockets equipped with an explosive warhead. Most RPGs can be carried by an individual soldier, and are frequently used as anti-tank weapons. These warheads are affixed to a rocket motor which propels the RPG towards the target and they ar... | Technology | Missiles | null |
26298 | https://en.wikipedia.org/wiki/Radiometric%20dating | Radiometric dating | Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the mater... | Physical sciences | Geochronology | Earth science |
26301 | https://en.wikipedia.org/wiki/Rocket | Rocket | A rocket (from , and so named for its shape) is a vehicle that uses jet propulsion to accelerate without using any surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely from propellant carried within the vehicle; therefore a rocket can fly in the va... | Technology | Space | null |
26310 | https://en.wikipedia.org/wiki/Reproduction | Reproduction | Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: asexual and sexual.
In asexual reproduction, an organism can reproduce without the involvement of another organism. Ase... | Biology and health sciences | Biology | null |
26350 | https://en.wikipedia.org/wiki/Radiation%20therapy | Radiation therapy | Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle accelerator. Radiation therapy may be curative in a number of types of cancer i... | Biology and health sciences | Medical procedures | null |
26378 | https://en.wikipedia.org/wiki/Rift%20Valley%20fever | Rift Valley fever | Rift Valley fever (RVF) is a viral disease of humans and livestock that can cause mild to severe symptoms. The mild symptoms may include: fever, muscle pains, and headaches which often last for up to a week. The severe symptoms may include: loss of sight beginning three weeks after the infection, infections of the brai... | Biology and health sciences | Viral diseases | Health |
26390 | https://en.wikipedia.org/wiki/Riemann%20integral | Riemann integral | In the branch of mathematics known as real analysis, the Riemann integral, created by Bernhard Riemann, was the first rigorous definition of the integral of a function on an interval. It was presented to the faculty at the University of Göttingen in 1854, but not published in a journal until 1868. For many functions a... | Mathematics | Integral calculus | null |
26397 | https://en.wikipedia.org/wiki/Red%E2%80%93black%20tree | Red–black tree | In computer science, a red–black tree is a self-balancing binary search tree data structure noted for fast storage and retrieval of ordered information. The nodes in a red-black tree hold an extra "color" bit, often drawn as red and black, which help ensure that the tree is always approximately balanced.
When the tree... | Mathematics | Data structures and types | null |
26404 | https://en.wikipedia.org/wiki/Risk%20management | Risk management | Risk management is the identification, evaluation, and prioritization of risks, followed by the minimization, monitoring, and control of the impact or probability of those risks occurring. Risks can come from various sources (i.e, threats) including uncertainty in international markets, political instability, dangers o... | Technology | Basics | null |
26441 | https://en.wikipedia.org/wiki/Red%20panda | Red panda | The red panda (Ailurus fulgens), also known as the lesser panda, is a small mammal native to the eastern Himalayas and southwestern China. It has dense reddish-brown fur with a black belly and legs, white-lined ears, a mostly white muzzle and a ringed tail. Its head-to-body length is with a tail, and it weighs betwee... | Biology and health sciences | Other carnivora | Animals |
26446 | https://en.wikipedia.org/wiki/Recreational%20mathematics | Recreational mathematics | Recreational mathematics is mathematics carried out for recreation (entertainment) rather than as a strictly research-and-application-based professional activity or as a part of a student's formal education. Although it is not necessarily limited to being an endeavor for amateurs, many topics in this field require no k... | Mathematics | Basics | null |
26463 | https://en.wikipedia.org/wiki/Rigel | Rigel | Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand the eponymof a star system of at least four stars that appear as a single blue-white point of ... | Physical sciences | Notable stars | null |
26469 | https://en.wikipedia.org/wiki/General%20recursive%20function | General recursive function | In mathematical logic and computer science, a general recursive function, partial recursive function, or μ-recursive function is a partial function from natural numbers to natural numbers that is "computable" in an intuitive sense – as well as in a formal one. If the function is total, it is also called a total recursi... | Mathematics | Computability theory | null |
26471 | https://en.wikipedia.org/wiki/Rat | Rat | Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus Rattus. Other rat genera include Neotoma (pack rats), Bandicota (bandicoot rats) and Dipodomys (kangaroo rats).
Rats are typically distinguished from mice by their ... | Biology and health sciences | Rodents | null |
26477 | https://en.wikipedia.org/wiki/Rust | Rust | Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3), and is typically associated with the corrosion of refined iron.
Giv... | Physical sciences | Redox reactions | Chemistry |
26478 | https://en.wikipedia.org/wiki/Real%20analysis | Real analysis | In mathematics, the branch of real analysis studies the behavior of real numbers, sequences and series of real numbers, and real functions. Some particular properties of real-valued sequences and functions that real analysis studies include convergence, limits, continuity, smoothness, differentiability and integrabilit... | Mathematics | Calculus and analysis | null |
26537 | https://en.wikipedia.org/wiki/Rose | Rose | A rose is either a woody perennial flowering plant of the genus Rosa (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be erect shrubs, climbing, or trailing, with stems that are often armed with sharp pri... | Biology and health sciences | Rosales | null |
26561 | https://en.wikipedia.org/wiki/Rank%20%28linear%20algebra%29 | Rank (linear algebra) | In linear algebra, the rank of a matrix is the dimension of the vector space generated (or spanned) by its columns. This corresponds to the maximal number of linearly independent columns of . This, in turn, is identical to the dimension of the vector space spanned by its rows. Rank is thus a measure of the "nondegener... | Mathematics | Linear algebra | null |
26573 | https://en.wikipedia.org/wiki/Rabbit | Rabbit | Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated form of livestock, and a pet, having a widespread effect on ecologies and cultures. ... | Biology and health sciences | Lagomorphs | null |
26590 | https://en.wikipedia.org/wiki/Relay | Relay | A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof.
Relays are used ... | Technology | Components | null |
26685 | https://en.wikipedia.org/wiki/Statistics | Statistics | Statistics (from German: , "description of a state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with a statistical population or a statist... | Mathematics | Mathematics | null |
26691 | https://en.wikipedia.org/wiki/Set%20%28mathematics%29 | Set (mathematics) | In mathematics, a set is a collection of different things; these things are called elements or members of the set and are typically mathematical objects of any kind: numbers, symbols, points in space, lines, other geometrical shapes, variables, or even other sets. A set may have a finite number of elements or be an in... | Mathematics | Mathematics: General | null |
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