42,772 articles
Nommo Valles
Nommo Valles: 200 km-wide channel system (vallis) on Venus at 40.7S, 87.3E, IAU-approved 2000, named for Dogon water deities of Mali; not detectable in Magellan radar imagery.
Nomograms
Nomograms: graphical charts of statistical prediction models with scales for each variable, used in medicine to compute individualized probabilities of clinical endpoints, notably in cancer prognosis (Partin tables).
Non-Abelian anyon
A non-Abelian anyon is a quasiparticle in a two-dimensional topological phase whose exchange applies a unitary matrix rather than a phase, the basis of topological quantum computation.
Non-Abelian band topology
Non-Abelian band topology is a branch of topological band theory in which multiband nodes carry non-commutative quaternion charges, making annihilation depend on the braiding path in momentum space.
Non-Abelian braiding
Non-Abelian braiding is the exchange of identical quasiparticles in a sequence whose final state depends on the order of the exchanges, so the operations do not commute.
Non-Abelian braiding of light
Non-Abelian braiding of light is the photonic realization of non-Abelian braiding, proposed in 2016 by Iadecola, Schuster, and Chamon and since demonstrated on photonic chips and in multimode fibers.
Non-Abelian frame charges
A non-Abelian frame charge is a topological invariant of band nodes in multiband systems, taking quaternion-group values so that braiding nodes changes their charges; first observed experimentally in 2021.
Non-abelian hidden subgroup problem
The non-abelian hidden subgroup problem asks a quantum computer to find a hidden subgroup of a finite non-commutative group, and no efficient general algorithm is known.
Non-Abelian synthetic gauge fields for ultracold atoms
Non-Abelian synthetic gauge fields for ultracold atoms are engineered laser-produced gauge potentials with non-commuting components that act on atoms' internal spin states, first proposed for optical lattices in 2005.
Non-Abelian topological charges of photonic bands
Non-Abelian topological charges of photonic bands are quaternion-valued labels that classify band degeneracies like nodal lines in multiband photonics, where the charges do not commute, so the order of loops changes the result.
Non-associative algebra
A non-associative algebra is an algebra over a field whose multiplication need not satisfy x(yz) = (xy)z; Lie, Jordan, and alternative algebras are the best-known examples.
Non-contact atomic force microscopy
Non-contact atomic force microscopy (nc-AFM) is a scanning probe technique that achieves true atomic resolution by oscillating a cantilever above a surface without touching it.
Non-critical string theory
Non-critical string theory is a string theory in a spacetime dimension other than the critical 26 or 10, made consistent by a linear dilaton or Liouville mode.
Non-dimensionalization
Non-dimensionalization rescales the variables of a governing equation by characteristic units so that the equation, its solutions, and its parameters become dimensionless, simplifying comparison and simulation.
Non-equilibrium plasma
Non-equilibrium plasma, also called non-thermal or cold plasma, is an ionized gas whose electrons reach about 10,000 K while the gas stays near ambient temperature.
Non-equilibrium steady state
A non-equilibrium steady state (NESS) is a state of a physical system in which macroscopic properties stop changing even as currents of energy, particles, or momentum flow through it continuously.
Non-equilibrium thermodynamics
Non-equilibrium thermodynamics is the branch of thermodynamics describing heat, mass, charge, and momentum transport and irreversible phenomena in systems not in global equilibrium, founded on Lars Onsager's 1931 reciprocal relations.
Non-essential and conditionally essential amino acids
Non-essential amino acids are the proteinogenic amino acids the body can synthesize de novo, while conditionally essential ones, like arginine and tyrosine, become dietary requirements under specific physiological conditions.
Non-Euclidean geometry
Non-Euclidean geometry, also known as non-Euclidean space, is geometry built on alternatives to Euclid's parallel postulate, arising in the early nineteenth century from the work of Gauss, Bolyai, and Lobachevski.
Non-Fermi liquid
A non-Fermi liquid, also known as a strange metal, is a metallic quantum state lacking well-defined electron quasiparticles due to strong quantum fluctuations, first observed experimentally in 1991 and since found in cuprates and heavy-fermion compounds.
Non-Gaussianity
Non-Gaussianity in cosmology is any deviation from Gaussian statistics in the primordial density fluctuations that seeded cosmic structure, probed through higher-order correlators such as the bispectrum, with Planck finding no primordial signal.
Non-Hermitian acoustic skin effect
The non-Hermitian acoustic skin effect is the acoustic realization of the non-Hermitian skin effect, in which bulk sound modes accumulate at the boundaries of non-reciprocal acoustic crystals, first demonstrated in 2021.
Non-Hermitian photonics
Non-Hermitian photonics is the study of optical systems that exchange energy with their environment through gain and loss, giving complex spectra and exceptional points used in sensing and lasers.
Non-Hermitian skin effect
The non-Hermitian skin effect (NHSE) is a phenomenon in non-Hermitian lattice systems where bulk eigenstates accumulate exponentially at open boundaries, with no Hermitian counterpart, observed in photonic, acoustic, and quantum platforms.
Non-Hermitian topological edge states
Non-Hermitian topological edge states are boundary modes of systems with gain, loss, or nonreciprocal couplings, where complex energies and the non-Hermitian skin effect break the bulk-boundary correspondence.
Non-Hermitian topological metamaterials
Non-Hermitian topological metamaterials are engineered wave systems combining topological band structures with gain, loss, or nonreciprocal coupling, yielding exceptional points and the non-Hermitian skin effect.
Non-ionizing radiation
Non-ionizing radiation is the part of the electromagnetic spectrum, plus ultrasound, whose photons cannot ionize atoms, spanning static fields, radio waves, microwaves, and most ultraviolet.
Non-isocyanate polyurethanes
Non-isocyanate polyurethanes (NIPUs) are polyurethane-type polymers formed without toxic isocyanates or phosgene, most often by polyaddition of cyclic carbonates with amines; first synthesized in 1957, they are developed for coatings, foams, and composites.
Non-isocyanate polyurethanes from CO2
Non-isocyanate polyurethanes from CO2, first achieved in 1957 by Dyer and Scott, are polymers made by reacting CO2-derived cyclic carbonates with amines, avoiding toxic phosgene.
Non-linear effects
Non-linear effects are deviations from a proportional relationship between the enantiomeric excess of a chiral catalyst and of its product, first reported by Henri Kagan in 1986.