All articles starting with N
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Natural American Spirit
Natural American Spirit, also called American Spirits, is an American cigarette brand founded in Santa Fe, New Mexico, in 1982, marketed as natural and 100% additive-free tobacco.
Natural and Cultural Heritage of the Ohrid region (site)
Natural and Cultural Heritage of the Ohrid region: transboundary mixed UNESCO World Heritage property (Albania, North Macedonia), inscribed 1979, extended 1980 and 2019, covering ancient Lake Ohrid, Ohrid town, and the Lin Peninsula; over 200 endemic species and severe eutrophication and development threats.
Natural and Culturo-Historical Region of Kotor
Natural and Culturo-Historical Region of Kotor: UNESCO World Heritage site in Montenegro's Boka Kotorska Bay, inscribed 1979 (criteria i–iv), 14,600 ha, on the Danger List 1979–2003 after the 1979 earthquake.
Natural area
A natural area is a tract of land or water that retains or recovers natural character without being undisturbed, or that possesses uncommon features of scientific or educational value.
Natural bond orbital analysis
Natural bond orbital (NBO) analysis is a computational chemistry method that transforms a calculated molecular wavefunction into localized orbitals, revealing bonding, atomic charges, hybridization, resonance, and donor-acceptor interactions.
Natural Born Killers
Natural Born Killers is Oliver Stone's 1994 satirical crime drama, from a Quentin Tarantino story, starring Woody Harrelson and Juliette Lewis as killer-celebrities Mickey and Mallory Knox; noted for MPAA cuts, UK censorship battles, and copycat-crime controversy.
Natural boundary
A natural boundary is a boundary of an analytic function's domain where every point is a singularity, blocking analytic continuation entirely, a concept introduced by Weierstrass in 1842.
Natural Bridge (Virginia)
Natural Bridge (Virginia) is a 200-foot limestone arch over Cedar Creek in Rockbridge County, bought by Thomas Jefferson in 1774, a National Historic Landmark since 1998, and Virginia's 37th state park since 2016.
Natural Bridge State Resort Park
Natural Bridge State Resort Park, one of Kentucky's four original state parks, is a forested park in Powell County whose centerpiece is a 78-foot natural sandstone arch.
Natural Bridges National Monument
Natural Bridges National Monument: Utah's first national monument (1908), protecting three large stream-eroded sandstone bridges, Sipapu, Kachina, and Owachomo, plus Ancestral Puebloan sites; first International Dark Sky Park (2007).
Natural burial
Natural burial, also called green or woodland burial, is body disposition without embalming, vaults, or non-biodegradable caskets in habitat-preserving grounds. Originated by Ken West at Carlisle, UK, in 1993; LCAs show lower climate impact than cremation.
Natural circulation
Natural circulation is coolant flow through a loop without pumps, driven by buoyancy from density differences; it removes decay heat passively in reactors like the ESBWR and AP1000.
Natural convection
Natural convection, also called free convection, is heat transfer in a fluid where buoyancy, arising from density differences caused by temperature gradients, drives the flow without any pump or fan.
Natural cycle in vitro fertilization
Natural cycle in vitro fertilization (NC-IVF) is IVF without ovarian stimulation, using the single egg of a natural menstrual cycle; it produced the first IVF birth in 1978.
Natural Cycles
Natural Cycles (NC°) is a Swedish contraceptive app that determines daily fertility status from basal body temperature and cycle data, the first FDA-cleared contraceptive app in 2018.
Natural decay series
A natural decay series is a chain of radioactive nuclides decaying from a long-lived parent to a stable end product, classically four chains headed by thorium, neptunium, and uranium.
Natural deduction
Natural deduction is a logical proof system, described by Gentzen and Jaśkowski in 1934, built by assuming temporary premises and discharging them, with an introduction and elimination rule for each connective.
Natural deep eutectic solvents
Natural deep eutectic solvents (NADES) are green solvents made from natural metabolites such as sugars, amino acids, and choline chloride, proposed by Choi and Verpoorte in 2011.
Natural disaster
A natural disaster is a serious disruption of a community caused by a hazardous natural event, such as an earthquake or flood, producing major human and economic losses.
Natural disasters in India
Natural disasters in India, also known as natural calamities in India, are recurrent floods, cyclones, earthquakes, landslides, droughts, and heat waves causing substantial loss of life and property.
Natural drainage system
A natural drainage system is the network of stream channels and land paths that collect runoff from a drainage basin and convey it to a common outlet.
Natural dye
A natural dye, also known as a vegetal dye, is a colorant extracted from plants, animals, minerals, microbes, or their waste, used to color textiles, food, and cosmetics.
Natural environment
Natural environment: the biotic (living) and abiotic (non-living) world of ecosystems, habitats and wilderness, studied via naturalness gradients; IPBES reports 47% natural ecosystem decline, 25% of species threatened, and 30x30 protection goals at 17.6% land coverage.
Natural experiment
A natural experiment is a study in which an external event, not the researcher, assigns people to different levels of an intervention, permitting causal estimation from observational data.
Natural family planning
Natural family planning (fertility awareness-based methods) identifies fertile days via cervical mucus, basal body temperature, or calendar rules to achieve or avoid pregnancy; typical-use failure rates range 2-23% by method.
Natural farming
Natural farming is an ecological crop production method avoiding tillage, synthetic fertilizers, and pesticides, developed by Masanobu Fukuoka and extended in India as Zero Budget Natural Farming.
Natural fiber
Natural fibers are plant, animal, or mineral-origin fibers such as cotton, flax, jute, and wool, used in textiles and composites. Key facts: renewable and biodegradable but water- and variability-limited; polyester holds 54% of fiber output; natural fiber composites cut GWP 20–50% versus glass fiber.
Natural Fiber Welding
Natural Fiber Welding is a Peoria, Illinois materials company founded in 2015 that makes plant-based, plastic-free materials, including the MIRUM leather alternative and PLIANT rubber outsoles.
Natural filtration
The natural filtration of a stochastic process is the filtration generated by the process itself, the smallest one to which it is adapted, recording only the process's own past behavior.
Natural flow regime
The natural flow regime is the characteristic pattern of streamflow in a river under natural conditions, defined by the magnitude, frequency, duration, timing, and rate of change of flows.