All articles starting with O
9,097 articles
Operator learning
Operator learning is a machine learning approach that trains neural networks to approximate mappings between infinite-dimensional function spaces, typically PDE solution operators, serving as fast surrogates in design and uncertainty quantification.
Operator overloading
Operator overloading is a programming language feature letting programmers define standard operators like + for their own types, central to C++, C#, Python, and Rust.
Operator product expansion
The operator product expansion (OPE) is a relation in quantum field theory, introduced by Kenneth Wilson in 1969, that expresses products of operators at nearby points as a sum of local operators.
Operator space theory
Operator space theory studies Banach spaces embedded in C-algebras, where matrix-level norms distinguish spaces that look identical as Banach spaces, merging C-algebra and Banach space theory.
Operator splitting
Operator splitting is a numerical time-integration method for ODEs and PDEs that applies sub-operators one after another, exact when they commute and otherwise carrying a splitting error.
Operator theory
Operator theory is the branch of functional analysis that studies linear operators, especially bounded linear maps between Hilbert and Banach spaces, and underlies the mathematics of quantum mechanics.
Operators in C and C++
Operators in C and C++: the shared operator set, 17-level C++ precedence and associativity rules, the C versus C++ conditional-operator difference, and overloading limits.
Operculina
Operculina Silva Manso is a pantropical genus of climbing vines in Convolvulaceae, type species O. turpethum, defined by an operculate capsule; includes medicinal jalapa and turpeth species.
Operculum (gastropod)
The operculum is a disk-like plate on the foot of many gastropods, sealing the shell opening when the animal retracts; most heterobranchs lack it, but opercula help identify living and fossil species.
Operetta
Operetta is a light musical theater that emerged in Paris and Vienna in the mid-nineteenth century. The French school was comic, while the Viennese school was sentimental and dance-oriented.
Opernhaus am Taschenberg
Opernhaus am Taschenberg, also called the Klengelsches Opernhaus, was an opera house in Dresden opened in 1667 with room for 2,000 spectators and became a Catholic court chapel in 1707.
Operon
Operon: group of contiguous bacterial genes with a common promoter transcribed as one polycistronic mRNA, proposed by Jacob and Monod in 1961; regulated by operators, repressors, and attenuation, and grouped into regulons.
OPET (fuel company)
OPET is a Turkish fuel distribution company founded in 1992 by Fikret and Nurten Öztürk, half owned by Koç Group, with about 1,882 stations under the OPET and SUNPET brands.
Opeth
Opeth, Swedish progressive metal/rock band from Stockholm formed in 1990, led by Mikael Åkerfeldt; known for Blackwater Park, Ghost Reveries, the 2011 clean-vocal turn on Heritage, and 2024's The Last Will and Testament.
Opevesostat
Opevesostat (ODM-208, MK-5684) is an oral, non-steroidal, first-in-class CYP11A1 inhibitor from Orion Pharma and Merck/MSD that blocks all steroid hormone synthesis; investigated in the CYPIDES and OMAHA phase 3 trials for metastatic castration-resistant prostate cancer.
Oph 11
Oph 11 (Oph 162225-240515, Oph 1622) is a wide ~240 AU binary of young brown dwarfs in Scorpius, discovered in 2006 by Jayawardhana and Ivanov; later spectra revised its masses above the planetary range.
Ophanim (אוֹפַנִּים)
Ophanim (אוֹפַנִּים, Ofanim), also called Galgallim, are the wheels of Ezekiel's throne-chariot vision, later ranked as an order of angels, second in Maimonides' hierarchy and identified with the Thrones in Christian angelology.
Ophel
The Ophel is the raised spur at the southern edge of Jerusalem's Temple Mount, between it and the City of David, with monumental Iron Age remains excavated since 1870.
Ophel inscription
The Ophel inscription, also called the Ophel pithos inscription, is a disputed seven-letter alphabetic inscription on a storage jar found in 2012 on the Ophel in Jerusalem.
Ophelia
Ophelia is Hamlet's beloved, Polonius's daughter, and Laertes's sister in Shakespeare's Hamlet; she goes mad in Act 4 Scene 5 and drowns, possibly by suicide, becoming an enduring icon in art, opera, film, and pop music.
Ophelia (2018 film)
Ophelia (2018 film) is a Claire McCarthy drama retelling Shakespeare's Hamlet from Ophelia's viewpoint, adapted by Semi Chellas from Lisa Klein's novel, starring Daisy Ridley, Naomi Watts, George MacKay, and Clive Owen; it premiered at Sundance 2018 and was released by IFC Films in 2019.
Ophelia (album)
Ophelia is Natalie Merchant's second solo album (Elektra, May 19, 1998), a concept song cycle of six female characters, dedicated to Allen Ginsberg, peaking at number 8 on the Billboard 200 and certified platinum.
Ophelia (Heyser)
Ophelia (c. 1900) is an oil-on-canvas painting by German painter Friedrich Wilhelm Theodor Heyser, held at Museum Wiesbaden, showing Shakespeare's Ophelia floating among water lilies; it drew worldwide attention in 2025 through Taylor Swift's music video.
Ophelia (painting)
Ophelia is John Everett Millais's 1851-52 Pre-Raphaelite oil painting at Tate Britain depicting Shakespeare's Hamlet heroine floating in a stream before drowning, painted outdoors in Surrey with Elizabeth Siddal posing in a bathtub.
Ophelia Brown
Ophelia Brown, born in 1986, is a British venture capitalist who founded Blossom Capital in London after stints at Index Ventures and LocalGlobe, investing early in Checkout.com and MoonPay.
Ophelia Dahl
Ophelia Dahl, daughter of Roald Dahl and Patricia Neal, co-founded Partners In Health in 1987 with Paul Farmer and others, led it as executive director 2001-2015, and chaired its board from 2002 to 2025; TIME100 2024, Radcliffe Medal 2023.
Ophelia Lovibond
Ophelia Lovibond (Ophelia Lucy Lovibond, born 1986), English actress known for Carina in Guardians of the Galaxy, Izzy Gould in W1A, Kitty Winter in Elementary, and Joyce in Minx; 2024 West End return in The Hills of California.
Ophellas
Ophellas was a Macedonian officer from Pella who served Ptolemy I as governor of Cyrene and died in 308 BC on an expedition against Carthage.
Ophellas's expedition against Carthage
Ophellas's expedition against Carthage was a 308 BC march by Ophellas, ruler of Cyrene, to aid Agathocles of Syracuse, who killed him and took his army.
Ophidiiformes
Ophidiiformes is an order of teleost fishes comprising the cusk eels, pearlfishes, brotulas, and relatives: almost exclusively marine bottom fishes with a worldwide tropical and temperate distribution.