All articles starting with H
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Helically Symmetric Experiment
The Helically Symmetric Experiment (HSX) is a stellarator fusion research device at the University of Wisconsin–Madison and the only stellarator in the world with a quasi-helically symmetric magnetic field configuration.
Helicarrier
The Helicarrier is a fictional flying aircraft carrier in Marvel Comics, serving as the headquarters of S.H.I.E.L.D. Created by Stan Lee and Jack Kirby, it debuted in 1965.
Helicase
Helicase: NTP-driven motor enzymes that unwind duplex DNA or RNA into single strands for replication, repair, recombination, and RNA metabolism. Classified into six superfamilies (SF1–SF6); discovered 1976; targeted by antiviral helicase-primase inhibitors and cancer drugs such as WRN inhibitors.
Helicase structure and mechanism
Helicase structure and mechanism describes how helicase enzymes use ATP hydrolysis to separate DNA strands, organized into six superfamilies built on conserved RecA-like motor cores.
Helicase-dependent amplification
Helicase-dependent amplification (HDA) is an isothermal DNA amplification method, reported in 2004, in which a helicase enzyme separates DNA strands, replacing PCR's thermal cycling and suiting point-of-care diagnostics.
Helicases in transcription and chromatin remodeling
Helicases in transcription and chromatin remodeling are ATP-dependent motor enzymes that slide, eject, or restructure nucleosomes to support transcription, including the SWI/SNF, ISWI, CHD, and INO80 remodeler families.
Helice
Helice (Ἑλίκη, Helike) was an ancient Achaian polis on the Gulf of Corinth, refuge of the Ionians per Herodotus, submerged by an earthquake in 373 BCE and buried under river alluvium; not the Thracian road station Helice nor the constellation name.
Helicene
Helicene is an ortho-fused polycyclic aromatic or heteroaromatic compound whose angularly arranged rings form a helix, making it chiral; hexahelicene is the prototype, and applications include enantioselective catalysis and spintronics.
Helichrysum
Helichrysum (everlasting flowers) is a genus of about 564 accepted Asteraceae species native from Europe and Africa to Australia, widely used in traditional medicine; H. italicum yields a commercially important essential oil.
Heliciculture
Heliciculture, also called snail farming, is the rearing of land snails for food or cosmetics, practiced since the 1st century BC, when Romans kept snail gardens.
Helicinidae
Helicinidae (Férussac, 1822) are operculate terrestrial snails of the neritimorph superfamily Helicinoidea, with 500-750 species in the Caribbean, Indo-Pacific islands, and Asian-Australian margins, distinguished by a calcareous operculum and one tentacle pair.
Helicity (chemistry)
Helicity in chemistry is the chirality of a helical or screw-shaped molecular entity, assigned the stereodescriptors P (right-handed) or M (left-handed), formalized by Cahn–Ingold–Prelog rules.
Helicity Injected Torus
The Helicity Injected Torus (HIT) is a series of plasma physics experiments at the University of Washington in Seattle that develop helicity injection current drive for magnetic confinement fusion.
Helicity injection
Helicity injection is a method of driving current in magnetized plasmas by adding magnetic helicity, used to sustain spheromaks and spherical tokamaks without a central solenoid.
Helicobacter
Helicobacter is a genus of gram-negative, spiral-shaped bacteria that colonize the stomach lining; its best-known species, H. pylori, causes chronic gastritis, peptic ulcers, and gastric cancer.
Helicobacter pylori
Helicobacter pylori, a spiral stomach bacterium discovered by Marshall and Warren in 1982, causes gastritis, peptic ulcers, and gastric cancer; their 1984 Lancet report earned the 2005 Nobel Prize.
Helicobacter pylori associated gastric ulcer
Helicobacter pylori associated gastric ulcer (ICD-11 DA60.1): a stomach ulcer caused by H. pylori infection, accounting for 70% of gastric ulcers; eradication therapy prevents recurrence and rebleeding.
Helicobacter pylori eradication therapy
Helicobacter pylori eradication therapy is a combination antibiotic and acid-suppressing treatment, usually 14 days long, that cures H. pylori infection, healing ulcers and reducing gastric cancer risk.
Helicobacter pylori induced gastritis
Helicobacter pylori induced gastritis (ICD-11 DA42.1) is stomach lining inflammation from H. pylori infection, progressing from acute to chronic and atrophic gastritis, a gastric cancer risk factor; discovered by Marshall and Warren in 1982, treated by eradication therapy.
Helicobacter-pylori associated duodenal ulcer
Helicobacter-pylori associated duodenal ulcer (ICD-11 DA63.1) is a duodenal ulcer caused by chronic H. pylori infection, which accounts for over 90% of duodenal ulcers; eradication therapy, now optimized bismuth quadruple therapy for 14 days, cures the ulcer and prevents recurrence.
Helicobasidium
Helicobasidium (violet root rot fungi) is a genus of Pucciniomycetes basidiomycetes in Helicobasidiales; species such as H. purpureum and H. mompa cause violet root rot of crops, while their Tuberculina asexual stage parasitizes rust fungi.
Helicoid peripapillary chorioretinal degeneration
Helicoid peripapillary chorioretinal degeneration (Sveinsson chorioretinal atrophy, atrophia areata) is a rare autosomal dominant TEAD1-related retinal dystrophy with bilateral wing-shaped chorioretinal atrophy radiating from the optic disc, onset in infancy, sometimes with congenital anterior polar cataracts.
Helicoidal impact-resistant composites
Helicoidal impact-resistant composites are fiber-reinforced laminates in which fiber layers rotate by a small angle, a bio-inspired arrangement that improves impact resistance and damage tolerance over conventional layups.
Helicon current drive
Helicon current drive is a proposed off-axis current drive method for tokamak plasmas using helicon waves near 0.5 GHz, pursued on the DIII-D tokamak for its predicted high efficiency.
Helicon plasma
A helicon plasma is a dense, low-temperature plasma produced efficiently by radio-frequency helicon waves in a magnetized gas, used in materials processing, electrodeless space propulsion, and fusion current drive.
Heliconia
Heliconia (lobster-claw, false bird-of-paradise) is the sole genus of Heliconiaceae in Zingiberales, tropical herbs with colorful bracts pollinated by hummingbirds; about 187 species from Mexico to tropical America and the Pacific, nearly half threatened.
Heliconia bihai
Heliconia bihai (macawflower, lobster claw) is a large rhizomatous Heliconiaceae herb native to Mexico, the Caribbean, and northern South America, hummingbird-pollinated, polymorphic in bract color, and cultivated as an ornamental, food, and medicine.
Helicoprion
Helicoprion, an extinct Permian eugeneodont cartilaginous fish (not a true shark) known from spiral tooth whorls embedded in the lower jaw; named by Karpinsky in 1899, resolved by 2013 CT scans of Idaho specimen IMNH 37899.
Helicopter
A helicopter is a rotorcraft that generates lift with engine-driven rotating blades, allowing vertical takeoff and landing, hovering, and flight forward, backward, and sideways; Igor Sikorsky's VS-300 of 1939 established the common single-rotor design.
Helicopter carrier
A helicopter carrier is a warship with a full-length or near-full-length flight deck built to embark, launch, and recover helicopters for amphibious assault, anti-submarine warfare, and disaster relief.