All articles starting with N
16,460 articles
Nonnegative matrix factorization
Nonnegative matrix factorization (NMF) approximates a nonnegative data matrix as the product of two smaller nonnegative matrices, giving additive, parts-based representations used for dimensionality reduction, topic extraction, and source separation.
Nonniacus
Nonniacus: ancient Gallic place name, Barrington Atlas map 14 grid G3, tentatively identified with Louignac in the commune of Ayen, Corrèze, France; attested as a Late Roman toponym.
Nonnus
Nonnus of Panopolis was a Greek poet of the fifth century CE from Panopolis in Upper Egypt, author of the Dionysiaca, the longest surviving ancient Greek epic.
NONO
NONO (p54nrb), non-POU domain-containing octamer-binding protein, a DBHS-family nuclear RNA/DNA-binding scaffold protein at Xq13.1; essential for NEAT1 paraspeckles, splicing, DNA repair, circadian rhythm; overexpressed in cancers and fused to TFE3 in papillary renal cell carcinoma.
Nonogram
Nonogram (Picross, Griddlers, Hanjie): picture logic puzzle where row and column number clues specify runs of filled cells revealing a hidden image. Invented independently in 1980s Japan by Non Ishida and Tetsuya Nishio; NP-complete to solve.
Nonomura Ninsei
Nonomura Ninsei (野々村仁清) was an early Edo period Japanese potter, active from about 1646, who perfected overglaze enamel decoration in Kyoto ware at his Omuro kiln.
Nonorganic visual loss
Nonorganic visual loss, also called functional visual loss, is reduced visual acuity or field with no organic lesion found, accounting for about 12% of neuro-ophthalmology diagnoses.
Nonoxynol-9
Nonoxynol-9 (N-9), a detergent spermicide in OTC vaginal contraceptives like Conceptrol and VCF, kills sperm by disrupting membranes but failed as an HIV microbicide and is not recommended for STI prevention.
Nonparametric regression
Nonparametric regression estimates the conditional mean function directly from data without pre-specifying a functional form such as linearity, at the cost of slower convergence and heavier data demands.
Nonparametric statistics
Nonparametric statistics, also known as distribution-free methods, is the branch of statistics that analyzes data without assuming a specific distribution, using rank-based tests, bootstrap resampling, and density estimation.
Nonpareils
Nonpareils, also called hundreds and thousands in the UK, are tiny round sugar-and-starch sprinkles about 1 mm across, distinct from jimmies, pearls, and dragees, and also name a chocolate-disc candy.
Nonpartisan Bloc for Cooperation with the Government
The Nonpartisan Bloc for Cooperation with the Government (Polish: Bezpartyjny Blok Współpracy z Rządem, BBWR) was an electoral organization backing Józef Piłsudski's Sanation regime in interwar Poland.
Nonpartisan elections of state supreme court justices
Nonpartisan elections of state supreme court justices are elections in which candidates run without party labels on the ballot, first used in Cook County, Illinois, in 1873.
Nonperturbative quantum gravity
Nonperturbative quantum gravity is the search for a quantum theory of the gravitational field that avoids perturbation theory on a fixed background, pursued mainly through loop quantum gravity, asymptotic safety, and causal set theory.
Nonpoint
Nonpoint is an American nu metal/alternative metal band from Fort Lauderdale, Florida, formed in 1998 around vocalist Elias Soriano and drummer Robb Rivera; known for "Bullet With a Name" and the 2026 album The Last Word.
Nonpoint source pollution
Nonpoint source pollution is water pollution from diffuse runoff of rainfall or snowmelt over land, rather than from a pipe, and it pollutes most impaired US waters.
Nonprehensile manipulation
Nonprehensile manipulation is robotic manipulation of objects without grasping them, using pushing, sliding, rolling, and flicking; its systematic study began with Matthew T. Mason's 1986 mechanics of pushing.
Nonprobability sampling
Nonprobability sampling is a survey method that selects units by convenience, judgment, or quotas rather than randomly, making it cheaper but harder to measure for error.
Nonprofit organization
A nonprofit organization, also known as a not-for-profit, is an organization whose surplus earnings cannot be distributed to owners or members; examples range from charities to universities.
Nonproliferative diabetic retinopathy
Nonproliferative diabetic retinopathy (NPDR) is the early stage of diabetic retinopathy, marked by microaneurysms, hemorrhages, exudates, IRMA, and venous beading without neovascularization, staged mild, moderate, or severe.
Nonpurulent mastitis associated with childbirth
Nonpurulent mastitis associated with childbirth, also called lactation or puerperal mastitis, is ICD-11 code JB45.1 and ICD-10-CM O91.2: breast inflammation without pus during pregnancy, the 42-day puerperium, or lactation.
Nonradial pulsation
A nonradial pulsation is a stellar oscillation in which the surface deforms in alternating inward and outward regions, described by spherical harmonics with angular degree ℓ greater than 0.
Nonradiating anapole modes
Nonradiating anapole modes are electromagnetic excitations in which electric and toroidal dipole radiation cancel by destructive interference, leaving strong fields confined inside a structure with no net far-field emission.
Nonreciprocal charge transport in superconducting devices
Nonreciprocal charge transport, also called the superconducting diode effect, occurs when the critical supercurrent differs by direction, so supercurrent flows without dissipation one way but with resistance the other.
Nonreciprocal mechanical metamaterials
Nonreciprocal mechanical metamaterials are architected materials that push back differently when loaded from opposite sides, breaking classical reciprocity through engineered geometry and nonlinearities, with uses in mechanical diodes and one-way wave control.
Nonreciprocal metamaterials
Nonreciprocal metamaterials are artificial composite materials in which waves pass differently in each direction, enabling devices like isolators, circulators, and one-way mirrors for light and sound.
Nonreciprocal photonic metasurface
A nonreciprocal photonic metasurface is an ultrathin, two-dimensional array of engineered scatterers that transmits or reflects light differently forward and backward, enabling optical isolation and circulation.
Nonreciprocal plasmonic routing
Nonreciprocal plasmonic routing is the direction-dependent control of surface plasmon polaritons so signals propagate one way but not the reverse, requiring broken reciprocity via magneto-optical, nonlinear, or time-modulated mechanisms.
Nonreciprocal wave propagation in active metamaterials
Nonreciprocal wave propagation in active metamaterials is wave transmission through engineered composites that, using external power or control, transmit one way and block the other, as in one-way isolators.
Nonresistance
Nonresistance is a pacifist stance refusing all force to resist evil, rooted in Christian teaching and the peace churches. Distinct from nonviolent resistance and pacifism broadly, it is now studied alongside civil resistance success-rate debates.