42,772 articles
Rear-view mirror
A rear-view mirror is a mirror on a motor vehicle that lets the driver see behind without turning around, first used on Ray Harroun's car at the 1911 Indianapolis 500.
Rearrangements in organic synthesis
Rearrangements in organic synthesis reorganize a preassembled substrate's carbon skeleton through bond migration, cleavage, or formation, converting one ring system into another in a single step, a mainstay of natural product total synthesis.
ReaxFF
ReaxFF is a reactive force field for molecular dynamics simulations, introduced by van Duin and Goddard in 2001, in which bonds form and break continuously.
Reaxys
Reaxys is a subscription-based chemistry database and research platform owned by Elsevier, launched in 2009, containing over 160 million substances and 69 million reactions searchable by structure or text.
REBCO coated conductor
A REBCO coated conductor is a second-generation high-temperature superconducting tape, a thin rare-earth barium copper oxide film on flexible metal, used chiefly in compact fusion magnets.
Rebecca Dodder
Rebecca Dodder is an American systems scientist at the EPA, a 2013 PECASE recipient who is Associate National Program Director for its Air, Climate, and Energy research program.
Rebecca Kramer-Bottiglio
Rebecca Kramer-Bottiglio, also known as Rebecca Kramer, is an engineer working in soft robotics, known for robotic skins and adaptive morphogenesis robots, who received the 2024 Waterman Award.
Rebecca Smethurst
Rebecca (Becky) Smethurst is a British astrophysicist at the University of Oxford who studies how supermassive black holes grow without galaxy mergers and runs the Dr Becky YouTube channel.
Rebekah Shirley
Rebekah Shirley is a Trinidad-born energy researcher and Deputy Regional Director of WRI Africa in Nairobi, appointed in 2023, whose work spans renewable energy policy and electric mobility.
Received view
The received view is a philosophy of science position identifying a scientific theory with an axiomatic linguistic structure, developed by Carnap, Hempel, and other logical empiricists.
Receiver function
A receiver function is a time series computed from teleseismic seismograms by deconvolution, imaging crustal and upper-mantle discontinuities such as the Moho beneath a seismic station.
Receiver operating characteristic
The receiver operating characteristic (ROC) curve, central to ROC analysis, plots a test's sensitivity against its false-positive rate as the decision threshold varies, with the area under the curve ranking competing tests.
Reception and spread of Maxwell's theory
The reception of Maxwell's electromagnetic theory took about 23 years, ending with Hertz's 1888 experiments, after which Heaviside and Hertz rewrote the equations in modern form.
Receptor model
A receptor model is a statistical method that estimates pollution source contributions from measured concentrations at a site, working backward from the data rather than from emissions.
Rechenmeister tradition
The Rechenmeister tradition was the German counterpart of Italian abbaco schools: writing and reckoning masters who taught commercial arithmetic in vernacular urban schools from the late 15th century.
Reciprocal lattice
The reciprocal lattice, also known as reciprocal space or the inverse lattice, is the Fourier transform of a crystal's direct lattice and the setting for describing diffraction.
Reciprocal space mapping
Reciprocal space mapping (RSM) is a high-resolution X-ray diffraction technique that maps intensity over an area of reciprocal space, revealing lattice parameters, strain, and mosaicity in crystals and epitaxial films.
Reciprocity law
A reciprocity law is a theorem of number theory relating solvability of congruences modulo different primes, exemplified by quadratic reciprocity, first proved by Gauss in 1796.
Recoflavone
Recoflavone (DA-6034, AJU-S56, GLH8NDE) is a synthetic eupatilin-derived flavonoid drug from Korea's Dong-A Pharmaceutical, developed for gastritis and dry eye disease, with minimal oral absorption and a phase III dry eye trial NCT06291194.
Recoil
Recoil is the backward momentum an object feels when it exerts a force on another, such as a gun pushing back when it fires a bullet.
Recoiling black hole
A recoiling black hole is one given a velocity kick by anisotropic gravitational-wave emission during a binary black hole merger, potentially displacing or ejecting it from its host galaxy.
Recollision
Recollision is the return of an electron, freed from an atom or molecule by a strong laser field, to its parent ion within about one optical cycle.
Recombination (cosmology)
In cosmology, recombination is the epoch about 380,000 years after the Big Bang when the universe cooled enough for neutral hydrogen to form, making the cosmos transparent to light.
Recombination line
A recombination line is an emission line produced when a free electron is captured by an ion and cascades downward, emitting photons at discrete frequencies.
Reconfigurable chiral plasmonics
Reconfigurable chiral plasmonics is the branch of nanophotonics studying plasmonic nanostructures whose chiroptical responses or 3D structural handedness can be changed after fabrication by an external stimulus.
Reconfigurable colloidal crystals
Reconfigurable colloidal crystals are ordered lattices of colloidal particles whose structure or symmetry can be deliberately changed by external stimuli such as light or temperature.
Reconfigurable plasmonics
Reconfigurable plasmonics is the branch of nanophotonics in which a plasmonic structure's geometry or optical response is actively changed after fabrication, most often using liquid gallium alloys.
Reconstruction conjecture
The Reconstruction conjecture, also known as the Kelly–Ulam conjecture, is an unsolved problem in graph theory asserting that every graph on at least three vertices is determined by its vertex-deleted subgraphs.
Recording studio
A recording studio, also called a music studio, is a facility for recording and mixing sound, built around a live room, isolation booths, and a control room with strict acoustic control.
Recreational mathematics
Recreational mathematics, also called mathematical recreations, is mathematics pursued for enjoyment rather than application, covering puzzles, games, paradoxes, magic tricks, and topological curiosities such as Möbius bands.