42,772 articles
Pavel Urysohn
Pavel Urysohn (Павел Самуилович Урысон) was a Russian mathematician who founded dimension theory, proved the metrization theorem, and formulated the Urysohn lemma before drowning in 1924 at 26.
Paving matroid
A paving matroid is a matroid in which every circuit has size at least the rank, making it one of the largest classes of matroids.
Pavle Savić
Pavle Savić (Павле Савић, 1909–1994) was a Serbian physical chemist who nearly discovered nuclear fission with Irène Joliot-Curie and founded Yugoslavia's Vinča Institute of Nuclear Sciences.
Pavle V. Radovanovic
Pavle V. Radovanovic, also published as P. V. Radovanovic, is a materials chemist and professor at the University of Waterloo who studies multifunctional doped semiconductor nanocrystals.
Pavonis Mons
Pavonis Mons, Latin for peacock mountain, is the central and smallest of the three Tharsis Montes shield volcanoes on Mars, about 14 km high, 375 km wide, straddling the equator, with nested summit calderas and lava tubes.
Paweł Hawrylak
Pawel Hawrylak is a Polish-Canadian theoretical condensed matter physicist known for the theory of quantum dots as artificial atoms, and a professor at the University of Ottawa.
Pawukon
Pawukon is a cyclical calendar used in Bali and Java since the 9th century, made of ten concurrent subcycles repeating every 210 days with no years, governing most Balinese rituals including temple anniversaries, Galungan, and Kuningan.
Payne rearrangement
The Payne rearrangement is a base-promoted, reversible isomerization of 2,3-epoxy alcohols that shifts the epoxide one position along the carbon chain, with inversion at C-2.
Payoff matrix
A payoff matrix is a table listing every combination of players' strategies in a game and the payoff each earns, written as an ordered pair per cell.
Payun Matru
Payún Matrú (Payun Matru), a Quaternary shield volcano with an 8-10 km summit caldera in Mendoza, Argentina, center of the 5,200 km² Payún Matrú volcanic field, source of Earth's longest known Quaternary lava flow.
Pazopanib
Pazopanib, sold as Votrient, is an oral tyrosine kinase inhibitor developed by GlaxoSmithKline and marketed by Novartis for advanced renal cell carcinoma and soft tissue sarcoma.
Pb1-xSnxSe topological crystalline insulator
Pb1-xSnxSe is a lead-tin selenide semiconductor that becomes a topological crystalline insulator above tin content x = 0.15, one of the first such materials shown experimentally.
PBE functional
The PBE functional, proposed by Perdew, Burke, and Ernzerhof in 1996, is a nonempirical generalized gradient approximation for exchange-correlation energy that became the de facto standard in solid-state physics.
PBR theorem
The PBR theorem is a 2012 no-go theorem in quantum foundations by Pusey, Barrett, and Rudolph ruling out models that treat the quantum state as mere information.
PbTaSe2
PbTaSe2, or lead tantalum selenide, is a non-centrosymmetric superconductor that superconducts near 3.7 to 3.8 K and hosts topological surface states, making it a stoichiometric candidate for a topological superconductor.
PC algorithm
The PC algorithm, named for Peter Spirtes and Clark Glymour, is a constraint-based causal discovery method that infers the structure of a causal directed acyclic graph from conditional independence tests on observational data.
PCB Piezotronics
PCB Piezotronics is an American manufacturer of vibration, pressure, force, and torque sensors in Depew, New York, founded in 1967 and known for its ICP sensors.
PCN-222
PCN-222, also known as MOF-545, is a highly stable, mesoporous zirconium-porphyrin metal-organic framework reported in 2012 by Hong-Cai Zhou and colleagues at Texas A&M University as a biomimetic catalyst.
PCO2
PCO2, or PaCO2, is the partial pressure of carbon dioxide dissolved in arterial or venous blood, normally 35 to 45 mmHg, and a marker of alveolar ventilation.
PCPr
PCPr (N-propyl-1-phenylcyclohexylamine), also known as phencyclamine or NPPCA, is a dissociative arylcyclohexylamine of the PCP family, seized in Germany in the late 1990s and controlled there since 1997.
PCR-GLOBWB
PCR-GLOBWB (PCRaster Global Water Balance) is an open-source global hydrology and water resources model developed at Utrecht University in the Netherlands, simulating soil moisture, groundwater, and human water use at daily time steps.
Pd–Cu single-atom alloy catalysts for semihydrogenation
Pd–Cu single-atom alloy catalysts are heterogeneous catalysts in which isolated palladium atoms in a copper surface split hydrogen while copper carries out selective semihydrogenation of alkynes to alkenes.
PDE-constrained optimization
PDE-constrained optimization is a class of optimization problems minimizing a cost functional subject to partial differential equations as constraints, underlying optimal control, inverse problems, and design, with the adjoint equation supplying gradients.
Pea soup fog
Pea soup fog, or pea-souper, is a thick yellowish or blackish fog colored by coal soot and sulfur dioxide, typified by London's fogs and the Great Smog of December 1952; the name comes from split-pea soup.
Peace Tower
The Peace Tower (Tour de la Paix) is the 92.2-meter central clock tower of Canada's Parliament Buildings in Ottawa, built from 1919 to 1927 as a First World War memorial.
Peak ground acceleration
Peak ground acceleration, or PGA, is the largest ground acceleration recorded at a point during an earthquake, usually expressed as a percentage of the acceleration of gravity, g.
Peak water
Peak water is the concept that freshwater availability or use can rise to a maximum and then decline, formalized by Peter Gleick and Meena Palaniappan in 2010.
PeakForce Tapping
PeakForce Tapping (PFT) is a proprietary atomic force microscopy mode developed by Bruker, productized in 2009, that images at controlled peak force while quantitatively mapping nanomechanical properties.
Peaks over threshold
Peaks over threshold (POT) is an extreme value theory method that retains and models all observations above a high threshold, fitted with the generalized Pareto distribution.
Peano arithmetic
Peano arithmetic (PA) is a formal axiomatic theory of the natural numbers, named for Giuseppe Peano's 1889 axioms, which is incomplete by Gödel's theorems and has non-standard models.