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Alfvén speed
The Alfvén speed is the characteristic speed of magnetic disturbances along field lines in a conducting plasma, proposed by Hannes Alfvén in 1942 and central to magnetohydrodynamics.
Alfvén surface
The Alfvén surface is the boundary around a magnetized star where the solar wind outruns the Alfvén speed, first crossed by Parker Solar Probe in 2021.
Alfvén wave
An Alfvén wave is a wave oscillating along magnetic field lines in an electrically conducting plasma, predicted by Hannes Alfvén in 1942, who won the 1970 Nobel Prize in Physics.
Alfvén's theorem
Alfvén's theorem, or the frozen-in flux theorem, states that in a perfectly conducting plasma the magnetic field is carried along with the fluid as if frozen into it.
ALG-pathway congenital disorders of glycosylation
ALG-pathway congenital disorders of glycosylation are inherited metabolic diseases in which defective ALG-family genes disrupt assembly of lipid-linked oligosaccharides in the endoplasmic reticulum, causing type I CDG; ALG6-CDG is the most common subtype.
ALG1-CDG
ALG1-CDG (formerly CDG-Ik, OMIM 608540) is a rare autosomal recessive N-glycosylation disorder caused by biallelic ALG1 variants on 16p13, impairing the first mannose addition step, with severe neurological multisystem disease and a diagnostic xeno-tetrasaccharide biomarker.
ALG11-CDG
ALG11-CDG (CDG-Ip) is a rare autosomal recessive N-glycosylation disorder caused by ALG11 mutations, causing epilepsy, developmental disability, microcephaly, and sensorineural deafness, with no specific treatment.
ALG12-CDG
ALG12-CDG (CDG-Ig, CDG1G) is a rare autosomal recessive congenital disorder of glycosylation from ALG12 (22q13.33) mannosyltransferase deficiency, adding the eighth mannose to the lipid-linked oligosaccharide; features include intellectual disability, hypotonia, low IgG, genital hypoplasia, coagulopathy; roughly 16 reported cases.
ALG13-CDG
ALG13-CDG (CDG type Is, EIEE36) is a rare X-linked congenital disorder of glycosylation caused by ALG13 gene variants, presenting in infancy with epileptic spasms, hypotonia, and developmental delay; transferrin tests are usually normal, so genetic sequencing confirms it.
ALG2-CDG
ALG2-CDG (CDG-Ii, CDG1I, mannosyltransferase 2 deficiency) is an ultra-rare autosomal recessive congenital disorder of glycosylation from ALG2 loss-of-function variants, causing infantile spasms, iris coloboma, cataract, developmental delay, and coagulopathy.
ALG3-CDG
ALG3-CDG (CDG-Id, OMIM 601110) is a rare autosomal recessive congenital disorder of glycosylation caused by ALG3 alpha-1,3-mannosyltransferase deficiency, causing truncated N-glycans, severe epilepsy, microcephaly, hypotonia, and multisystem disease.
ALG6-CDG
ALG6-CDG, also called congenital disorder of glycosylation type Ic (CDG-Ic), is an inherited autosomal recessive metabolic disease causing hypotonia, seizures, and developmental delay in infants, first reported in 1998.
ALG8-CDG
ALG8-CDG (CDG-Ih, glucosyltransferase 2 deficiency) is a rare autosomal recessive congenital disorder of N-linked glycosylation from ALG8 (11q14.1) mutations, causing severe hepatic, gastrointestinal, neurologic, and coagulation symptoms with poor prognosis.
ALG9-CDG
ALG9-CDG (CDG-IL, CDG1L) is a rare autosomal recessive N-glycosylation disorder from ALG9 (11q23) mannosyltransferase 7-9 deficiency, causing infantile epilepsy, hypotonia, cysts, or lethal fetal skeletal dysplasia.
Algae
Algae: diverse photosynthetic organisms (including cyanobacteria, seaweeds, diatoms) across four kingdoms; 50,589 living species, 3-billion-year fossil record, primary producers, food and industrial uses, harmful blooms.
Algae fuel
Algae fuel, a third-generation biofuel from microalgae or kelp, was pursued by DOE's Aquatic Species Program from 1978; costs of $1.64 to over $30 per gallon and harvesting, drying, and extraction bottlenecks still limit commercialization.
Algal bloom
Algal bloom: rapid growth of algae or cyanobacteria in fresh or marine water; harmful algal blooms (HABs) produce toxins like microcystins, driven by nutrient pollution, warming, and stratification, exemplified by Lake Erie.
Algal toxicosis
Algal toxicosis: animal poisoning from toxins of harmful algal blooms (cyanobacteria, dinoflagellates, diatoms). Key toxins include microcystins, anatoxins, saxitoxins, brevetoxins, domoic acid; WOAH-listed wildlife disease.
AlGaN deep-ultraviolet light-emitting diode
An AlGaN deep-ultraviolet light-emitting diode (DUV LED) is a semiconductor light source whose aluminum gallium nitride active region emits at 200–365 nm, serving as a mercury-free replacement for mercury lamps in sterilization, UV curing, and phototherapy.
Algarve
Algarve: southernmost region of mainland Portugal (district of Faro, 16 municipalities), NUTS II region, former Kingdom of the Algarve conquered in 1249; tourism-led economy, Ria Formosa park, CCDR Algarve governance.
Algarve Surf School
Algarve Surf School, also Algarve Surf School & Camp, is a Sagres, Portugal surf school founded in 1996 by coach Sergio Wu Brandao, with sites in Sagres and Praia do Amado, ASI-certified instructors, and camp weeks from 490 euros.
Algarvensis UNESCO Global Geopark
Algarvensis UNESCO Global Geopark (Geoparque Algarvensis), in Portugal's Algarve across Loulé, Silves, and Albufeira, designated 24 April 2026; 1,386 km2, 330-million-year geological record, Metoposaurus algarvensis fossil site, Loulé Salt Mine.
Algebra
Algebra, historically called the cossic art, is a branch of mathematics studying operations and structures, from solving equations with unknowns to abstract algebra's groups, rings, and fields.
Algebra of random variables
The algebra of random variables is the set of arithmetic operations, addition, multiplication, and division, that can be performed on random variables, with rules for finding the resulting distributions.
Algebra over a field
An algebra over a field, or K-algebra, is a vector space over a field k with a bilinear multiplication, making it both a ring and a vector space.
Algebraic closure
An algebraic closure of a field F is an algebraically closed algebraic extension of F; every field has one, unique up to isomorphism fixing F.
Algebraic closure (model theory)
In model theory, the algebraic closure of a set is the collection of elements lying in some finite set definable from it, and in algebraically closed fields it matches the usual field-theoretic algebraic closure.
Algebraic cobordism
Algebraic cobordism, a cohomology theory for algebraic varieties built by Marc Levine and Fabien Morel, is the algebro-geometric analog of complex cobordism and the universal oriented cohomology theory on smooth varieties over fields of characteristic zero.
Algebraic combinatorics
Algebraic combinatorics is an area of mathematics applying algebra, topology, and geometry to combinatorial problems, defined by method rather than subject matter and named in the late 1970s.
Algebraic Combinatorics (journal)
Algebraic Combinatorics (ALCO) is an open-access mathematics journal publishing papers where algebra and combinatorics interact, founded in 2018 by editors who resigned from Springer's Journal of Algebraic Combinatorics.