All articles starting with H
20,046 articles
Hypermagnesemia
Hypermagnesaemia (hypermagnesemia; ICD-10-CM E83.41) is an elevated serum magnesium level, defined above 2.6 mg/dL (1.05 mmol/L). Rare, usually caused by kidney failure with magnesium intake; causes reflex loss, hypotension, respiratory depression; treated with calcium gluconate, furosemide, or dialysis.
Hypermanganesemia with dystonia
Hypermanganesemia with dystonia is a rare autosomal recessive disorder in which mutations in SLC30A10 or SLC39A14 cause manganese to accumulate in the blood and brain.
Hypermarket
Hypermarket: very large self-service store combining supermarket food retail with general merchandise, defined as over one third food sales and 2,500 m² or more. Invented by Carrefour at Sainte-Geneviève-des-Bois, France, 15 June 1963; now losing share to other grocery channels.
Hypermassive neutron star
A hypermassive neutron star (HMNS) is a briefly stable merger remnant whose mass exceeds the maximum nonrotating neutron star mass, supported only by differential rotation and heat.
Hypermedia
Hypermedia is multimedia content, including text, images, audio, and video, connected by links users follow; Ted Nelson coined the term in 1965, and the World Wide Web realizes it.
Hypermetabolism
Hypermetabolism is an abnormally fast metabolism causing weight loss and fatigue, seen after severe burns (REE 40-80% above normal, lasting up to two years), sepsis, eating disorder recovery, hyperthyroidism, and cancer.
Hypermetamorphosis
Hypermetamorphosis: a form of complete insect metamorphosis (holometaboly) in which larval instars differ markedly in form, seen in Mantispidae, Meloidae blister beetles, Rhipiphoridae, and Strepsiptera, with type I and type II patterns.
Hypermethioninemia
Hypermethioninemia, also called methioninemia, is an excess of the amino acid methionine in the blood, arising from inherited enzyme defects, liver disease, or unusually high dietary intake.
Hypermethioninemia due to glycine N-methyltransferase deficiency
Hypermethioninemia due to glycine N-methyltransferase deficiency (GNMT deficiency, OMIM 606664) is a rare autosomal recessive disorder causing permanent marked hypermethioninemia with high AdoMet, normal AdoHcy, and mild liver enzyme elevations.
Hypermetropia
Hypermetropia, also called hyperopia or farsightedness, is a refractive error in which light focuses behind the retina with accommodation relaxed, blurring near vision; caused by short axial length or flat cornea, corrected with plus lenses.
Hypermobile Ehlers-Danlos syndrome
Hypermobile Ehlers-Danlos syndrome (hEDS), formerly EDS type III, is the most common Ehlers-Danlos type: a clinically diagnosed connective tissue disorder with joint hypermobility, no known gene, prevalence about 1:3,100, and updated criteria due December 2026.
Hypermobility (joints)
Joint hypermobility, also called being double-jointed, means joints with unusually large range of movement; assessed by the Beighton Score, it ranges from an asymptomatic trait to hypermobility spectrum disorders and hypermobile Ehlers-Danlos syndrome.
Hypermodernism (chess)
Hypermodernism (chess): 1920s school of Nimzowitsch, Réti, Tartakower, Alekhine, Grünfeld, Breyer holding the centre should be controlled by pieces and fianchettoed bishops, not occupied by pawns; produced Nimzo-Indian, King's Indian, Grünfeld, Alekhine's Defence.
Hypernatremia
Hypernatremia is a serum sodium above 145 mmol/L from a water deficit relative to sodium, causing thirst and neurologic symptoms; treatment is controlled water replacement, with recent evidence favoring faster correction in admission-related and severe cases.
HyperNEAT
HyperNEAT is an indirect encoding method for evolving artificial neural networks, in which a CPPN generates connection weights from node coordinates; it extends NEAT and was introduced in 2009.
Hypernetworks
A hypernetwork (hypernet) is a neural network that generates the weights of another network, the target, introduced by David Ha, Andrew Dai, and Quoc V. Le in 2016.
HyperNormalisation
HyperNormalisation (2016) is a 166-minute BBC documentary by Adam Curtis, released 16 October 2016 on BBC iPlayer, arguing that since the 1970s elites built a simplified fake world; the title term comes from Alexei Yurchak's 2006 book on late Soviet life.
Hypernova
A hypernova is an exceptionally energetic stellar explosion, generally a broad-lined Type Ic supernova with energy about ten times that of a typical supernova, often accompanying long-duration gamma-ray bursts.
Hypernucleus
A hypernucleus is a subatomic bound system in which a nucleus of protons and neutrons contains at least one hyperon, a baryon with strange quarks.
Hyperolius
Hyperolius (reed frogs, African reed frogs), genus Rapp 1842 of family Hyperoliidae; most speciose sub-Saharan amphibian genus, ~146 species, includes H. viridiflavus superspecies with 50+ subspecies.
Hyperon puzzle
The hyperon puzzle is the conflict in neutron star physics between the predicted appearance of hyperons in stellar cores and observed masses above two solar masses, which hyperons make hard to explain.
Hyperoodon
Hyperoodon, bottlenose whales, is a beaked-whale genus (Ziphiidae) with two antitropical species: H. ampullatus of the North Atlantic and H. planifrons of the Southern Ocean; deep-diving, whaling-depleted, COSEWIC-listed.
Hyperoplus lanceolatus
Hyperoplus lanceolatus (Le Sauvage, 1824), greater sandeel or great sandeel, largest Ammodytidae sand lance of the NE Atlantic to 40 cm; dark snout spot, two palate teeth, non-protrusible upper jaw; COI barcoding cannot separate it from Ammodytes tobianus.
Hyperosmia
Hyperosmia is a quantitatively increased sense of smell, defined as an exceptionally high psychophysical olfactory test score (above the 90th percentile); distinct from olfactory intolerance, and often contradicted by objective testing showing hyposmia.
Hyperosmolar hyperglycemic state
Hyperosmolar hyperglycemic state (HHS), formerly hyperglycemic hyperosmolar nonketotic coma: a life-threatening type 2 diabetes emergency with glucose over 600 mg/dL, osmolality over 320 mOsm/kg, dehydration without ketoacidosis, and 5–16% mortality.
Hyperostosis corticalis generalisata
Hyperostosis corticalis generalisata, or van Buchem disease, is a rare autosomal recessive craniotubular hyperostosis caused by a 52-kb SOST regulatory deletion, causing skull and mandible thickening, cranial nerve palsies, and hearing loss, mainly in the Dutch population.
Hyperostosis cranialis interna
Hyperostosis cranialis interna (HCI, OMIM 144755) is an extremely rare autosomal dominant bone dysplasia, first described in 1990, causing endosteal hyperostosis of the calvaria and skull base with cranial nerve I, II, V, VII, and VIII entrapment; mapped to chromosome 8p21, SLC39A14 implicated.
Hyperostosis of skull
Hyperostosis of skull (ICD-10 M85.2), chiefly hyperostosis frontalis interna, benign nodular thickening of the frontal bone's inner table, common in postmenopausal women, usually incidental.
Hyperoxia
Hyperoxia is the exposure of body tissues to oxygen at a higher than normal partial pressure, which can cause oxygen toxicity affecting the nervous system and lungs.
Hyperparameter (machine learning)
A hyperparameter in machine learning is a configuration value, such as the learning rate or number of layers, set before training rather than learned from the data.