All articles starting with H

Homocysteine

Homocysteine, a sulfur amino acid from methionine metabolism (hyperhomocysteinemia >15 µmol/L), is lowered by B vitamins, but trials show no reduction in heart attack or death; used mainly for B-vitamin deficiency and homocystinuria testing.

Homocystinuria

Homocystinuria (HCU), also called classic homocystinuria when caused by CBS deficiency, is a rare autosomal recessive metabolic disorder of homocysteine breakdown, causing lens dislocation, skeletal changes, and thromboembolism, treated with vitamin B6, low-methionine diet, and betaine.

Homocystinuria due to cystathionine beta-synthase deficiency

Homocystinuria due to cystathionine beta-synthase deficiency is an inherited disorder of sulfur amino acid metabolism in which homocysteine accumulates, causing thrombosis, lens dislocation, and skeletal changes.

Oct 21, 2026

Homocystinuria without methylmalonic aciduria

Homocystinuria without methylmalonic aciduria (functional methionine synthase deficiency; cblE, cblG, cblDv1) is a rare autosomal recessive cobalamin metabolism disorder with megaloblastic anemia, high homocysteine, low methionine, and normal methylmalonic acid, treated with hydroxocobalamin.

Homodyne detection

Homodyne detection is an optical technique in quantum optics that mixes a weak signal with a strong phase-locked local oscillator to measure one quadrature of the field.

Homoepitaxy

Homoepitaxy is the growth of an epitaxial crystal layer on a substrate of the same material, typically by CVD step-flow growth, and underlies silicon carbide power devices.

Homoeroticism

Homoeroticism denotes erotic desire or representation between same-sex individuals, distinct from homosexuality as identity or relationship; used since Ferenczi (1911) and central to LGBTQ history, art history, and media studies.

Homogeneity and heterogeneity

Homogeneity and heterogeneity describe whether a property or constituent is uniformly distributed throughout a material, classifying mixtures, determining sampling error in analysis, and distinguishing catalysts by phase.

Homogeneous assay

A homogeneous assay is a biochemical assay format that measures molecular binding or enzymatic activity with no separation or wash step, so mix-and-read protocols suit automation and high-throughput screening.

Homogeneous base catalysis

Homogeneous base catalysis is a biodiesel production method in which a soluble base catalyst, typically sodium methoxide, NaOH, or KOH, converts oils into fatty acid methyl esters.

Homogeneous broadening

Homogeneous broadening is spectral line broadening that affects every atom or molecule in a sample the same way, giving identical line shapes; its causes include lifetime, collisional, and thermal broadening, and its line shape is Lorentzian.

Homogeneous charge compression ignition

Homogeneous charge compression ignition (HCCI) is an engine combustion mode where a premixed fuel-air charge autoignites under compression, offering high efficiency with very low NOx and particulate emissions.

Homogeneous coordinates

Homogeneous coordinates, also called projective coordinates, represent points of projective space by tuples defined only up to a nonzero scalar, letting points at infinity be written as ordinary tuples.

Homogeneous differential equation

A homogeneous differential equation is an ordinary differential equation that is either first-order with right-hand side depending only on y/x, or linear with zero forcing term.

Homogeneous freezing

Homogeneous freezing is the spontaneous freezing of a supercooled liquid droplet without a solid particle, occurring below about −38 °C and driving ice formation in cirrus clouds.

Homogeneous function

A homogeneous function, also known as a homogeneous map, scales by a fixed power when all its arguments are scaled by the same factor, as in the Cobb–Douglas function.

Homogeneous isotropic turbulence

Homogeneous isotropic turbulence (HIT) is an idealized, simplest form of turbulence whose statistics are invariant under translation and rotation, serving as the theoretical baseline for real flows.

Homogeneous nucleation

Homogeneous nucleation is the spontaneous formation of crystal or droplet nuclei in the bulk of a supersaturated solution, supercooled melt, or vapor, without any foreign surface.

Homogeneous space

A homogeneous space is a space on which a group acts transitively, so any point can be carried to any other by some group element.

Homogeneous transformation matrix

A homogeneous transformation matrix is a 4×4 matrix combining a rotation and a translation, representing the pose of one rigid body relative to another in robotics.

Homogenic

Homogenic is Björk's third solo studio album, released 22 September 1997 on One Little Indian and Elektra. Produced with Mark Bell, Guy Sigsworth, and Howie B, it fuses distorted beats with an Icelandic string octet; UK peak number 4, US Billboard 200 peak number 28.

Homogenization (chemistry)

Homogenization in chemistry is a mechanical process that shrinks droplets or particles in an emulsion, most often by forcing fluid at high pressure through a narrow valve.

Oct 21, 2026

Homogentisate 1,2-dioxygenase

Homogentisate 1,2-dioxygenase (HGD, HGO, EC 1.13.11.5) is an Fe(II)-dependent cupin enzyme converting homogentisate to maleylacetoacetate in tyrosine catabolism; its gene sits at 3q13.33 and its deficiency causes alkaptonuria.

Homograph

Homograph: a word spelled identically to another word but differing in meaning, sometimes in pronunciation (bass, bow, lead). Related to homophone and heteronym; English contains over 1,500 homographs.

Homography (computer vision)

In computer vision, a homography is a projective transformation, represented by a 3×3 matrix, that maps points between planes, estimated from four point correspondences and used in panorama stitching, augmented reality, and document rectification.

Homography estimation

Homography estimation computes the 3×3 projective transformation that maps points between two images of a planar scene, underpinning image stitching, object detection, and camera calibration.

Homol Oil and Gas Field

Homol Oil and Gas Field is an offshore oil and gas field in the Gulf of Mexico off southeastern Mexico, operated by Pemex and discovered in 2002.

Oct 21, 2026

Homolion

Homolion (Ὁμόλιον, Latin Homolium) was an ancient Magnesian polis on Thessaly's Macedonian border near modern Omolio, controlling the Vale of Tempe; known for Iron Age tholos tombs, gold treasures, bronze coinage, and a possible Zeus Homoloios sanctuary.

Homologation reaction

A homologation reaction, also called homologization, is a chemical transformation that lengthens a molecule's carbon skeleton by one carbon, typically a methylene group, as in the Arndt–Eistert synthesis.