All articles starting with P
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Polynomial kernel
The polynomial kernel is a kernel function in machine learning that computes a scaled, shifted inner product raised to a degree, letting support vector machines learn nonlinear boundaries.
Polynomial long division
Polynomial long division, also known as the polynomial division algorithm, divides one polynomial by another to produce a quotient and a remainder, like arithmetic long division.
Polynomial method
The polynomial method is a collection of techniques in combinatorics and number theory that controls finite sets of points with suitably chosen polynomials, emerging in the late 2000s.
Polynomial regression
Polynomial regression is a form of regression analysis that models a response as a polynomial in the predictors, fitted by least squares like ordinary linear regression.
Polynomial ring
A polynomial ring, also called a polynomial algebra, is a ring whose elements are polynomials in one or more indeterminates, written R[x] over a base ring R.
Polynomial spiral path
A polynomial spiral path is a plane curve whose curvature is a polynomial function of arc length, used in robotics and autonomous driving to generate smooth vehicle paths.
Polynomial Szemerédi theorem
The polynomial Szemerédi theorem is a result in additive combinatorics, proved by Bergelson and Leibman in 1996, extending Szemerédi's theorem to polynomial patterns in dense integer sets.
Polynomial transformation (statistics)
A polynomial transformation adds powers and cross-products of existing predictors as new features, so a linear regression model can represent curved relationships while remaining linear in its coefficients.
Polynomial-time approximation scheme
A polynomial-time approximation scheme (PTAS) is an algorithmic framework for NP-hard optimization problems that, given an accuracy parameter ε, returns a solution within a factor of the optimum in polynomial time.
Polynya (полынья)
A polynya (полынья), from Russian, is an opening of persistent or recurring open water within sea ice; coastal polynyas produce about 10% of Antarctic sea ice.
Polyol
A polyol is an organic compound carrying more than one hydroxyl group, a term covering sugar alcohol sweeteners like sorbitol and the industrial polyols used to make polyurethanes.
Polyol method
The polyol method, or polyol process, is a wet-chemical synthesis in which a heated polyol acts as solvent, reducing agent, and stabilizer, yielding metal and oxide nanoparticles.
Polyol pathway
The polyol pathway is a two-step metabolic route converting glucose to fructose via sorbitol; in hyperglycemia it can carry up to 30% of glucose, driving diabetic complications.
Polyol synthesis
Polyol synthesis is a chemical method that reduces metal salts dissolved in a heated polyol to produce metal and metal oxide nanoparticles of controlled size, shape, and composition.
Polyolefin
A polyolefin, also called a polyalkene, is a polymer prepared from an olefin such as ethylene or propylene; polyethylene and polypropylene together make up over half of global plastic production.
Polyolefin metathesis
Polyolefin metathesis is a metal-catalyzed method that cleaves and rebuilds the backbones of polyolefin plastics such as polyethylene and polypropylene, upcycling them into fuels or propylene.
Polyolefin upcycling
Polyolefin upcycling is the catalytic conversion of polyolefin plastics like polyethylene and polypropylene into higher-value products, cleaving only a small fraction of the polymer's bonds.
Polyolefin upcycling by hydrogenolysis
Polyolefin upcycling by hydrogenolysis is a catalytic chemical recycling method using metal catalysts and hydrogen to convert waste polyethylene and polypropylene into fuels, lubricants, and waxes below 300 °C.
Polyolefin vitrimer
A polyolefin vitrimer is a cross-linked network of polyolefin chains, such as polyethylene or polypropylene, joined by dynamic covalent bonds that let the thermoset-like material be reprocessed and recycled above a temperature threshold.
Polyomaviridae
Polyomaviridae: family of small non-enveloped circular dsDNA viruses (~5 kbp, 40–45 nm virions) infecting mammals, birds, and fish; includes SV40, BK, JC, and Merkel cell polyomaviruses, the only known human oncovirus in the family.
Polyomino
Polyomino: edge-connected shapes made of unit squares, named by Solomon W. Golomb in 1953. Includes dominoes through pentominoes, Tetris tetrominoes, NP-complete tiling, and enumeration up to n=59.
Polyopisthocotylea
Polyopisthocotylea, subclass of monogenean flatworms (Platyhelminthes) with a haptor bearing multiple clamps or suckers; gill blood-feeders of fish, sister-group issues with Monopisthocotylea, Polystomatidae basal, Lethacotyle clampless.
Polyorchidism
Polyorchidism (supernumerary testis) is a rare congenital anomaly with one or more extra testes, usually triorchidism, left-sided, mostly scrotal; managed by observation or orchidopexy/orchidectomy depending on malignancy risk.
Polyorthoester
Polyorthoesters, also known as poly(ortho esters) or POEs, are synthetic biodegradable polymers developed since 1970 whose surface erosion releases incorporated drugs at a roughly constant rate.
Polyosteoarthritis
Polyosteoarthritis, also called polyarthrosis, is a degenerative joint disorder in which cartilage deteriorates and bone changes occur across multiple joints; it is coded FA05 in ICD-11.
Polyoxetane
Polyoxetane is a polyether whose backbone consists of repeating trimethylene oxide units, made by ring-opening polymerization of oxetane and used in energetic propellant binders and lithium battery electrolytes.
Polyoxin
Polyoxin: peptidyl nucleoside antifungal antibiotics from Streptomyces cacaoi var. asoensis, discovered 1965; polyoxin D zinc salt (FRAC 19, Oso, Affirm) inhibits chitin synthase as a UDP-GlcNAc mimic for crop disease control.
Polyoxometalate water oxidation catalysis
Polyoxometalate water oxidation catalysis is the use of polyoxometalates, anionic metal-oxo clusters of tungsten, molybdenum, or vanadium, to catalyze water oxidation into oxygen, a field begun in 2008 with ruthenium-substituted polyoxotungstates.
Polyoxyethanyl-alpha-tocopheryl sebacate
Polyoxyethanyl-alpha-tocopheryl sebacate (PTS), CAS 263015-34-5, a vitamin E-derived nonionic micelle-forming surfactant; GRAS (GRN 202, Zymes LLC, 2006) as a coenzyme Q10 solubilizer in dietary supplements.
Polyoxymethylene
Polyoxymethylene, also called polyacetal, acetal, or polyformaldehyde, is a crystalline engineering thermoplastic made from formaldehyde, with metal-like hardness and low friction that make it a standard metal-replacement material in cars, electronics, and machinery.