42,772 articles
Linear particle accelerator
A linear particle accelerator, or linac, is a machine that speeds charged particles along a straight path, used in radiotherapy and as injectors for larger machines.
Linear polarization
Linear polarization is the electromagnetic-wave state in which the electric field oscillates along a single fixed line, produced by reflection at Brewster's angle, scattering, and polarizing filters.
Linear potential
In quantum mechanics, a linear potential, V(x) = Cx, subjects a particle to a constant force. It is exactly solvable, with Airy-function solutions used at turning points.
Linear programming relaxation
A linear programming relaxation is the linear program obtained by deleting an integer program's integrality constraints; its optimum bounds the integer optimum and supports rounding, branch-and-bound, and cutting planes.
Linear quadrupole ion trap
The linear quadrupole ion trap (LIT) is a mass spectrometry device that stores ions along a linear quadrupole axis, offering higher ion capacity and sensitivity than the 3D ion trap.
Linear regression
Linear regression, covering multiple linear regression, models a response variable as a linear function of one or more explanatory variables, most commonly estimated by the method of least squares.
Linear response function
The linear response function describes how a system's observable changes to first order under a small external perturbation, expressed as the susceptibility and given in quantum mechanics by the Kubo formula.
Linear sampling method
The linear sampling method (LSM) is a non-iterative inverse-scattering technique, introduced by David Colton and Andreas Kirsch in 1996, that reconstructs the shape of unknown scatterers from multistatic far-field wave data.
Linear solvation energy relationship
A linear solvation energy relationship (LSER) is an equation applying solvent parameters in linear regression to express solvent effects on reaction rates or equilibrium constants.
Linear span
The linear span, also called the linear hull, of a set of vectors is the set of all their finite linear combinations, and it forms the smallest subspace containing them.
Linear stability analysis
Linear stability analysis determines whether small disturbances to an equilibrium of a dynamical system grow or decay, by linearizing the equations and examining eigenvalues; it gives only a local verdict.
Linear subspace
A linear subspace, also called a vector subspace, is a subset of a vector space that is itself a vector space under the same addition and scalar multiplication; examples include lines and planes through the origin.
Linear system
A linear system is a mathematical model of a dynamic process whose output obeys superposition, forming the basis of automatic control, signal processing, circuit analysis, and structural mechanics.
Linear system of divisors
A linear system of divisors, also called a linear series, is a family of linearly equivalent effective divisors on an algebraic variety, parametrized by projective space.
Linear temporal logic
Linear temporal logic (LTL) is a modal temporal logic over infinite sequences of states, proposed by Amir Pnueli in 1977 and now the most widely used temporal logic in computer science.
Linear-chain cluster state in carbon-12
The linear-chain cluster state in carbon-12 is a hypothesized excited configuration with its three alpha particles aligned end to end, proposed by Morinaga in the 1950s.
Linear-quadratic model
The linear-quadratic model is a radiation biology model relating cell survival to linear and dose-squared terms; it underlies the biologically effective dose used to compare radiotherapy fractionation schedules.
Linear-sweep voltammetry
Linear-sweep voltammetry (LSV) is an electroanalytical technique in which the electrode potential is swept linearly with time while the current is measured, used to characterize redox reactions and quantify electroactive species.
Linearity
Linearity is the property of a function or system satisfying additivity and homogeneity, meaning T(u+v) = T(u)+T(v) and T(av) = aT(v); it enables superposition, unlike nonlinear problems.
Linearization
Linearization is the replacement of a nonlinear system by a linear one approximating it near a chosen point, typically an equilibrium, with eigenvalues of the Jacobian determining local stability.
Linearized gravity
Linearized gravity, also called the linearized theory of gravitational waves, is the weak-field approximation to general relativity, keeping the Einstein field equations only to first order.
Lineation
Lineation is any repeated, penetrative alignment of linear elements in a rock, the linear counterpart of foliation in structural geology; stretching lineations track maximum elongation and help predict ore shoot geometry.
LINER
A LINER, or low-ionization nuclear emission-line region, is a class of galaxy nucleus first described by Tim Heckman in 1980 and found in about 30% of nearby galaxies.
Linewidth enhancement factor
The linewidth enhancement factor, also called the Henry factor, is a dimensionless parameter quantifying amplitude–phase coupling in semiconductor lasers; introduced by Charles H. Henry in 1982, it multiplies laser linewidth by 1 + α².
Lingjun Li
Lingjun Li (李灵军) is an analytical chemist and professor at the University of Wisconsin–Madison known for discovering more than 500 novel neuropeptides and for TEMI, a single-cell-resolution mass spectrometry imaging method.
Linking high-harmonic generation from gases and solids
Linking high-harmonic generation from gases and solids refers to a 2015 experiment showing that high harmonics from zinc oxide crystals arise from electron-hole recollision, the solid analog of gas-phase HHG.
Linking number
The linking number is an integer invariant in knot theory that counts, with sign, how many times one closed curve winds around another; Gauss introduced it in 1833.
Linnaeus's flower clock
Linnaeus's flower clock, or Horologium Florae, is a scheme by Carl Linnaeus for telling time from the opening and closing of flowers, published in 1751.
Linnea M. Avallone
Linnea M. Avallone is an American atmospheric chemist known for airborne instruments measuring trace gases and cirrus clouds, now NSF Chief Officer for Research Facilities.
Linoleic acid
Linoleic acid (linoleate) is an omega-6 polyunsaturated fatty acid, 18 carbons with two cis double bonds, that humans cannot synthesize and must get from vegetable oils, nuts, and seeds.