All articles starting with N
16,460 articles
Non-linear least squares
Non-linear least squares is a parameter estimation method that fits models nonlinear in their parameters by minimizing squared residuals, typically with the Gauss-Newton or Levenberg-Marquardt algorithm.
Non-local means
Non-local means (NL-means) is an image denoising algorithm introduced by Buades, Coll, and Morel in 2005, which estimates each pixel from similar patches found anywhere in the image.
Non-local thermodynamic equilibrium
Non-local thermodynamic equilibrium (non-LTE, or NLTE) is the condition of a gas or plasma in which radiative processes, not local collisions, set atomic energy-state populations.
Non-malignant and non-cirrhotic portal vein thrombosis
Non-malignant and non-cirrhotic portal vein thrombosis (NCPVT, non-cirrhotic non-tumoral PVT) is portal vein thrombosis without cirrhosis or malignancy, caused by myeloproliferative neoplasms, thrombophilia, or local factors, treated with at least 6 months of anticoagulation.
Non-mammalian and plant galactosyltransferases
Non-mammalian and plant galactosyltransferases are enzymes of plants, fungi, and bacteria that transfer galactose from UDP-sugar donors to build cell-wall polysaccharides and microbial surface glycans.
Non-Medical Prescribing
Non-medical prescribing is prescribing by healthcare professionals other than doctors or dentists, chiefly nurses and pharmacists. Originating in UK 1992 legislation, it includes supplementary and independent models, with Cochrane evidence of outcomes comparable to medical prescribing.
Non-megaloblastic macrocytosis
Non-megaloblastic macrocytosis is an elevated red cell volume (MCV above 100 fL) with intact DNA synthesis, caused by alcohol use, chronic liver disease, hypothyroidism, reticulocytosis, and certain drugs.
Non-metric multidimensional scaling
Non-metric multidimensional scaling (NMDS) is a statistical technique that represents objects as points in low-dimensional space, preserving only the rank order of observed dissimilarities, not their numerical values.
Non-metropolitan county
Non-metropolitan county: an English local government area under the Local Government Act 1972 (shire county) with a county council above non-metropolitan districts; 21 two-tier counties remain as of 2025, covering about 20 million people, now slated for unitarisation.
Non-mevalonate pathway
Non-mevalonate pathway, also called MEP or DOXP/MEP pathway, makes isoprenoid precursors IPP and DMAPP from pyruvate and glyceraldehyde 3-phosphate in bacteria, plant plastids, and apicomplexan parasites; absent in mammals, targeted by fosmidomycin at DXR.
Non-monogamy
Non-monogamy (ethical or consensual non-monogamy, CNM) covers polyamory, open relationships, swinging, and polyfidelity: multi-partner arrangements by explicit consent. Research finds satisfaction roughly equal to monogamy, with rising US interest and partial legal recognition.
Non-negative least squares
Non-negative least squares (NNLS) is a constrained regression method fitting a linear least squares model with every coefficient zero or positive, used in deconvolution and unmixing.
Non-negative matrix factorization
Non-negative matrix factorization (NMF) is a family of algorithms approximating a nonnegative matrix as a product of two lower-rank nonnegative matrices, giving additive, parts-based representations of data.
Non-Nernstian pH dependence of ORR/HOR kinetics
Non-Nernstian pH dependence of ORR/HOR kinetics is the deviation of oxygen and hydrogen electrode reaction rates from the pH shift predicted by the Nernst equation.
Non-Newtonian fluid
A non-Newtonian fluid is a fluid whose viscosity changes with shear rate rather than staying constant; ketchup, paint, blood, and cornstarch-water mixtures are common examples.
Non-normal modal logic
A non-normal modal logic is a modal logic weaker than the smallest normal logic K, lacking necessitation or the K axiom, and interpreted over neighborhood (Scott–Montague) models.
Non-nucleophilic magnesium electrolytes
Non-nucleophilic magnesium electrolytes are liquid electrolytes for rechargeable magnesium batteries whose magnesium-carrying species do not attack electrophilic cathodes such as sulfur, unlike early Grignard-based electrolytes.
Non-obstructive hypertrophic cardiomyopathy
Non-obstructive hypertrophic cardiomyopathy (nHCM, ICD-11 BC43.11) is HCM without a significant LVOT pressure gradient (LVOT <30 mmHg at rest and provoked), treated with beta blockers or verapamil/diltiazem, with no approved targeted therapy.
Non-occlusive mesenteric ischaemia
Non-occlusive mesenteric ischaemia (NOMI), also nonocclusive mesenteric ischemia, is intestinal ischemia without mesenteric vessel obstruction, caused by low-flow states and vasospasm; treated with resuscitation, intra-arterial vasodilators, and surgery.
Non-orbital rocketry
Non-orbital rocketry is rocketry that reaches high altitude or space on suborbital trajectories without achieving orbital speed. It spans model, mid-power, and professional sounding rockets.
Non-orientable mechanical metamaterial
A non-orientable mechanical metamaterial is a metamaterial lacking a consistent orientation, through Möbius-strip geometry or non-orientable order in frustrated lattices, enabling mechanical memory and non-Abelian responses.
Non-oriented electrical steel
Non-oriented electrical steel (NOES), also called CRNGO, is a flat-rolled iron-silicon alloy with uniform magnetic properties in all directions, the core material of electric motors and generators.
Non-orthogonal multiple access
Non-orthogonal multiple access (NOMA) is a radio access technique for 5G that transmits several users' signals on the same resource, separating them at receivers by successive interference cancellation.
Non-oscillatory scheme
A non-oscillatory scheme is a numerical method for hyperbolic partial differential equations that suppresses spurious oscillations near shocks and discontinuities while keeping high-order accuracy in smooth regions.
Non-oxidative phase of the pentose phosphate pathway
The non-oxidative phase of the pentose phosphate pathway is the fully reversible, cytosolic set of reactions that interconverts pentose phosphates and glycolytic intermediates, yielding no NADPH or ATP.
Non-partisan democracy
Non-partisan democracy: elections without party labels, from US nonpartisan municipal ballots (over 75% of cities) to Uganda's no-party system; effects on turnout, candidate quality, and representation.
Non-penetrative sex
Non-penetrative sex, or outercourse, is sexual activity without penetration of vagina, anus, or mouth. Covers definitions, practices, pregnancy and STI risks, risk-reduction guidance, and therapeutic uses.
Non-phenolic aryl alkyl ethers
Non-phenolic aryl alkyl ethers are ethers in which an alkyl group bonds through oxygen to a benzenoid or polycyclic aromatic ring, as in methoxyarenes and naphthyl methyl ethers.
Non-places
A non-place (French: non-lieu) is a concept coined by anthropologist Marc Augé in 1992, describing spaces like airports, hotels, and malls that lack relational, historical, or identity meaning.
Non-player character
A non-player character, or NPC, is a character in a game not controlled by a player: run by a gamemaster in tabletop role-playing games, and by software in video games.