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Merger (gravitational-wave astronomy)
A merger in gravitational-wave astronomy is the final collision of two black holes or neutron stars that spiraled together, recorded on Earth as a transient ripple in spacetime.
Merging enzymatic and photoredox catalysis
Merging enzymatic and photoredox catalysis, often called photoenzymatic catalysis or photobiocatalysis, unites light-driven radical chemistry with enzyme selectivity, chiefly through flavin-dependent ene-reductases, enabling enantioselective dehalogenations and radical cyclizations.
Merian Gold Mine
The Merian Gold Mine is an open-pit gold mine in northeastern Suriname operated by Newmont Suriname, which reached commercial production in October 2016 after construction began in 2014.
Meridianiite
Meridianiite is a naturally occurring sulfate mineral, magnesium sulfate undecahydrate (MgSO₄·11H₂O), stable only below about 2 °C and named for Mars's Meridiani Planum.
Merle Tuve
Merle Tuve (1901–1982) was an American experimental physicist who built an early accelerator-based nuclear physics program and led development of the radio proximity fuze in World War II.
Meromixis
Meromixis is the condition of a lake in which the water column never fully mixes, leaving dense bottom water permanently unmixed; the term was coined in 1935 by limnologist Ingo Findenegg.
Meromorphic function
A meromorphic function is a function of a complex variable that is holomorphic on a domain except at isolated poles, exemplified by rational functions, tan z, and the gamma function.
Merphos
Merphos (tributyl phosphorotrithioite, CAS 150-50-5, Folex) is an organophosphorus cotton defoliant, cancelled in the US and unapproved in the EU, neurotoxic, converting to tribufos (DEF).
MERRA-2
MERRA-2, the Modern-Era Retrospective analysis for Research and Applications, Version 2, is a NASA atmospheric reanalysis providing consistent weather and climate data from 1980 to the present.
Merril Eisenbud
Merril Eisenbud (1915–1997) was an American environmental health scientist, founding director of the Atomic Energy Commission's Health and Safety Laboratory, author of Environmental Radioactivity, and New York City's first Environmental Protection Administrator.
Mersenne prime
A Mersenne prime is a prime number of the form 2^p − 1, named after Marin Mersenne. The largest known prime, found in 2024, is one.
Mersenne primes
Mersenne primes are prime numbers of the form 2^p − 1 with p prime, named for Marin Mersenne; 52 are known, and they correspond to even perfect numbers.
Mertens function
The Mertens function, M(x) = Σ μ(n), sums the Möbius function up to x. Mertens conjectured |M(x)| < √x in 1897; Odlyzko and te Riele disproved it in 1985.
Mertonian norms
The Mertonian norms, known by the acronym CUDOS, are four imperatives that sociologist Robert K. Merton proposed in 1942 as the ethos of modern science: universalism, communism, disinterestedness, and organized skepticism.
Mervin Joe Kelly
Mervin Joe Kelly (1894–1971) was an American industrial physicist whose Bell Labs career ran from 1918 to 1959, ending as president and chairman of the board.
Mesabi Range
The Mesabi Range, also known as the Mesabi Iron Range, is an iron-mining district in northeastern Minnesota, the largest of Minnesota's three iron ranges, discovered in 1890.
Mesaverde Group
Mesaverde Formation (Mesaverde Group), Upper Cretaceous sandstone, shale, and coal unit along the Western Interior Seaway margin, first named 1875-1877 at Mesa Verde, Colorado; raised to group rank in several basins and a major tight-gas target in Wyoming, Utah, and Colorado.
Mescaline
Mescaline is a naturally occurring psychedelic alkaloid found in peyote and San Pedro cacti, first isolated by Arthur Heffter in 1897 and synthesized in 1929.
Meselson–Stahl experiment
The Meselson–Stahl experiment was a 1957–1958 experiment by Matthew Meselson and Franklin Stahl at Caltech showing that each daughter DNA molecule keeps one parental strand and one new strand.
Mesh morphing
Mesh morphing, also called mesh deformation or mesh movement, reshapes a computational mesh by moving its nodes without changing connectivity, used instead of remeshing for moving boundaries and shape optimization.
Mesh-refinement software frameworks for numerical relativity
Mesh-refinement software frameworks for numerical relativity let codes place fine grids where physics demands them and coarse grids elsewhere, with Carpet the dominant example since 2003.
Meshfree method
A meshfree method is a numerical technique that approximates solutions of partial differential equations using scattered points, with no explicit connectivity between nodes, useful for large deformations and fracture.
Meshless method
A meshless method is a numerical technique that solves partial differential equations using scattered points or particles, useful where mesh distortion breaks finite element analysis.
Mesityl oxide
Mesityl oxide is a colorless, oily liquid ketone with a pungent honey-like odor, made by dehydrating diacetone alcohol and used as a solvent and chemical intermediate.
Mesitylene
Mesitylene, also called sym-trimethylbenzene, is a symmetric aromatic hydrocarbon (C₉H₁₂) occurring in coal tar and petroleum, used as a solvent, paint thinner component, and chemical intermediate.
Meso compound
A meso compound is an achiral molecule with two or more stereocenters that is superimposable on its mirror image, with an internal plane of symmetry; meso-tartaric acid is the classic example.
Mesoamerican Long Count calendar
The Mesoamerican Long Count calendar, or Maya Long Count, is the ancient Maya's linear day count from a mythological creation date, giving each day a unique position.
Mesoarchean
The Mesoarchean is the third of four Archean Eon eras, spanning 3200 to 2800 million years ago, an interval that records the stabilization of the first large cratons.
Mesocyclone
A mesocyclone is a storm-scale region of cyclonic rotation, typically 2 to 6 miles in diameter, found in the right rear flank of a supercell thunderstorm and defined by a Doppler radar rotation signature.
Mesomeric effect
The mesomeric effect, also called the resonance effect, is the effect of a substituent on reaction rates and equilibria through p- or π-orbital overlap and charge delocalization, symbol M.