All articles starting with N
16,460 articles
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-gonococcal urethritis
Non-gonococcal urethritis (NGU), also called nonspecific urethritis, is inflammation of the male urethra without evidence of gonorrhea, a common sexually transmitted condition caused chiefly by Chlamydia trachomatis and Mycoplasma genitalium and treated with doxycycline.
Non-governmental organization
A non-governmental organization (NGO) is any non-profit, voluntary citizens' group organized locally, nationally, or internationally, known for delivering services, humanitarian aid, monitoring policy, and encouraging political participation.
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 metamaterials
Non-Hermitian metamaterials are engineered structures whose waves obey non-Hermitian operators because they exchange energy through gain, loss, or nonreciprocal couplings, realized in optics, acoustics, circuits, and mechanics.
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-Hispanic whites
Non-Hispanic whites: U.S. residents reporting White race and non-Hispanic origin, 191.7 million (57.8%) in the 2020 census, the largest group, declining in both count and share; also called White alone non-Hispanic.
Non-Hodgkin lymphoma
Non-Hodgkin lymphoma (NHL): a diverse group of immune-system cancers of lymphocytes, distinct from Reed-Sternberg cell-marked Hodgkin lymphoma. Indolent or aggressive B-, T-, or NK-cell subtypes; treated with chemotherapy, immunotherapy, transplant, or watchful waiting.
Non-inferiority testing
Non-inferiority testing is a clinical trial analysis approach showing a new treatment is not unacceptably worse than the active standard, by ruling out a pre-specified margin of loss.
Non-inferiority trial
A non-inferiority trial is a randomized clinical trial testing whether a new treatment is not unacceptably worse than an active comparator, used when a placebo would be unethical.
Non-insulinoma pancreatogenous hypoglycemia syndrome
Non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS) is a rare cause of endogenous hyperinsulinemic hypoglycemia without an insulinoma, marked by postprandial neuroglycopenia, negative 72-hour fast and imaging, positive calcium stimulation testing, and nesidioblastosis-like histology, often after gastric bypass.
Non-intrusive load monitoring
Non-intrusive load monitoring, also called energy disaggregation, estimates the power consumed by individual appliances from a single metering point, avoiding the wiring and submeters intrusive monitoring requires.
Non-invasive and partially invasive brain–computer interfaces
Non-invasive and partially invasive brain–computer interfaces (BCIs) record brain activity without penetrating brain tissue, using scalp EEG or electrodes placed under the skull, as in ECoG and endovascular Stentrode implants.
Non-invasive aspergillosis
Non-invasive aspergillosis is the group of Aspergillus diseases in which the fungus colonizes body surfaces or cavities without invading tissue or blood vessels, unlike invasive aspergillosis.
Non-invasive brain stimulation
Non-invasive brain stimulation (NIBS) is a class of techniques that modulate brain activity through the intact skull without surgery, used in research and to treat depression, stroke, and Parkinson's disease.
Non-invasive cardiac diagnostics (practice)
Non-invasive cardiac diagnostics is the cardiology practice of diagnosing heart disease with tests that do not enter the body, such as ECG, echocardiography, and stress testing.
Non-invasive glucose monitoring
Non-invasive glucose monitoring (NIGM) measures blood glucose through the skin or in body fluids without drawing blood, for diabetes management and screening; no fully non-invasive device holds FDA clearance.
Non-invasive prenatal screening
Non-invasive prenatal screening, also called NIPT or cfDNA screening, is a maternal blood test analyzing fetal DNA to screen for chromosomal abnormalities like Down syndrome from about 10 weeks of pregnancy.
Non-invasive vagus nerve stimulation
Non-invasive vagus nerve stimulation (nVNS) is a technique that stimulates the vagus nerve through the skin at the ear or neck, treating epilepsy, depression, and headaches.
Non-invasive ventilation
Non-invasive ventilation is positive pressure ventilation delivered through a tight-fitting mask or helmet rather than a tube, used mainly for COPD exacerbations, pulmonary edema, and weaning.
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-judicial punishment
Non-judicial punishment (NJP), also called Article 15, Captain's Mast, or Office Hours, is UCMJ Article 15 commander-imposed discipline for minor offenses without court-martial, with a right to demand trial except under the vessel exception.
Non-League football
Non-League football is the collective term for English men's and women's leagues situated below the Premier League and the three divisions of the EFL.
Non-lethal weapon
A non-lethal weapon, more accurately called a less-lethal weapon, is a device meant to incapacitate a person with a lower risk of death than firearms.
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.