42,772 articles
Laser-induced fluorescence
Laser-induced fluorescence (LIF) is a spectroscopy method in which a laser tuned to an absorption transition excites atoms or molecules, and the emitted fluorescence identifies and measures them.
Laser-induced graphene
Laser-induced graphene is a porous, conductive graphene-like carbon made by lasing carbon-rich materials such as polyimide, first reported in 2014 by James Tour's group at Rice University.
Laser-induced periodic surface structures
Laser-induced periodic surface structures (LIPSS), or ripples, are quasi-periodic grating-like surface patterns that self-organize when intense laser pulses strike solids such as metals, semiconductors, and insulators.
Laser-plasma instabilities
Laser-plasma instabilities (LPI), including stimulated Raman and Brillouin scattering, arise when intense laser light interacts with plasma, draining energy and degrading compression in inertial confinement fusion.
Laser-produced plasma X-ray source
A laser-produced plasma X-ray source is a device that focuses high-power laser pulses onto solid, liquid, or gas targets, creating plasma that emits X-rays for time-resolved diffraction, spectroscopy, and microscopy.
Laser–plasma interaction
Laser–plasma interaction (LPI) is the physics of how intense laser light couples to ionized matter, producing instabilities like Raman scattering that limit inertial confinement fusion and enable plasma accelerators.
Lasso (statistics)
The lasso, or least absolute shrinkage and selection operator, is a regression method introduced by Robert Tibshirani in 1996 that shrinks some coefficients to exactly zero, giving sparse, interpretable models.
Last Generation (climate group)
Last Generation, known in German as Letzte Generation, is a climate activist group formed in 2021, famous for road blockades in which members glued themselves to the roadway.
Last Glacial Maximum
The Last Glacial Maximum was the most recent interval when global ice sheets peaked, about 26,500 to 19,000 years ago, dropping sea level by roughly 130 meters.
Last Glacial Period
The Last Glacial Period, known as the Last Ice Age or Devensian, spanned about 115,000 to 11,700 years ago, when ice sheets grew over North America and northern Eurasia.
Last Interglacial
The Last Interglacial, known in Europe as the Eemian, was the warm period from about 129,000 to 116,000 years ago, when sea level stood several meters higher than today.
Last observation carried forward
Last observation carried forward (LOCF) is a statistical imputation method that fills missing values in longitudinal data with each subject's last observed value, long common in clinical trials.
László Babai
László Babai is a Hungarian mathematician and theoretical computer scientist at the University of Chicago, best known for his 2015 breakthrough algorithm for graph isomorphism and for work on interactive proofs.
László Zechmeister
László Zechmeister (1889–1972) was a Hungarian chemist who helped revive column chromatography, wrote the first handbook on the method, and studied carotenoid pigments at Caltech from 1940.
Latamoxef
Latamoxef, also known as moxalactam, is a broad-spectrum synthetic oxa-beta-lactam antibiotic of the cephalosporin family, discovered by Shionogi, given intravenously, and limited chiefly by bleeding risk.
Late Antique Little Ice Age
The Late Antique Little Ice Age (LALIA) was a proposed cold interval in the Northern Hemisphere from 536 to about 660 AD, triggered by volcanic eruptions.
Late Cretaceous
The Late Cretaceous is the younger epoch of the Cretaceous Period, from 100.5 to 66 million years ago, ending with the extinction of the non-avian dinosaurs.
Late Heavy Bombardment
The Late Heavy Bombardment, also called the lunar cataclysm, is a hypothesized period of intense asteroid impacts in the inner Solar System around 3.9 billion years ago.
Late Paleozoic icehouse
The Late Paleozoic icehouse, also called the Karoo Ice Age, was Earth's longest Phanerozoic ice age, lasting from about 370 to 260 million years ago.
Late Pleistocene
The Late Pleistocene, also known as the Upper Pleistocene or Tarantian, is the final division of the Pleistocene Epoch, from 129,000 to 11,700 years ago.
Late veneer
The late veneer is chondritic meteoritic material that geochemical models add to Earth's mantle after core formation, explaining why highly siderophile elements like platinum remain abundant there.
Late-stage 18F-deoxyfluorination
Late-stage 18F-deoxyfluorination is the fluorine-18 replacement of an oxygen-bearing functional group, most often a phenolic hydroxyl, as one of the final steps in synthesizing a PET radiotracer.
Late-stage C–H borylation
Late-stage C–H borylation is a chemical reaction that converts a carbon–hydrogen bond in a complex molecule into a carbon–boron bond, typically with an iridium catalyst.
Late-stage C–H methylation
Late-stage C–H methylation is the direct conversion of a C–H bond in a complex molecule, such as a drug candidate, into a carbon–methyl bond without prefunctionalization.
Late-stage functionalization
Late-stage functionalization (LSF) is a synthetic chemistry strategy that selectively modifies late intermediates or finished complex molecules, such as drug leads, to install new functional groups.
Latent change score model
A latent change score (LCS) model is a structural equation model that estimates change over time between latent variables measured on repeated occasions, in univariate or bivariate forms.
Latent class analysis
Latent class analysis, also known as the latent class model, is a statistical method that sorts cases into unobserved subgroups, called latent classes, using categorical variables.
Latent Dirichlet allocation
Latent Dirichlet allocation (LDA) is a generative probabilistic model in which each document is a mixture over latent topics, introduced by Blei, Ng, and Jordan in 2003 and the standard starting point for topic modeling.
Latent factor mixed model
A latent factor mixed model (LFMM) is a regression method that tests genetic loci for association with environmental variables while correcting for population structure through latent factors.
Latent growth curve model
A latent growth curve model is a structural equation modeling method that estimates change over time by treating each person's intercept and slope as latent variables.