All articles starting with P
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Policy gradient methods
Policy gradient methods are reinforcement learning algorithms that optimize a policy directly by ascending the estimated gradient of expected reward, starting with REINFORCE in 1992.
Policy Making
Policy making: the decision process by which individuals, groups, or institutions establish policies for plans, programs, or procedures. Covers the policy cycle, rational and incremental (Lindblom) models, evidence-informed decision-making, participation, and crisis governance.
Policy mix
The policy mix is the combination of a government's fiscal stance and the central bank's monetary stance, which together determine nominal demand, inflation, and output in an economy.
Policy surveillance
Policy surveillance is a study design in public health law research that systematically tracks and codes the content of laws across jurisdictions and over time, producing quantitative legal datasets for evaluation.
Policybazaar
Policybazaar is an Indian online insurance comparison and distribution platform launched in 2008, owned by PB Fintech, which earns commissions from insurers on completed sales.
Policygenius
Policygenius, legally PolicyGenius Inc. and originally incorporated as KnowltOwl Inc., was a New York-based online insurance marketplace founded in 2014, which Zinnia acquired in April 2023.
Polidexide sulfate
Polidexide sulfate (INN; also polydexide sulfate, brand Secholex) is a crosslinked dextran anion-exchange resin and bile acid sequestrant formerly used for hypercholesterolaemia in the UK, withdrawn in the mid-1970s over impurity-related safety concerns.
Polidocanol
Polidocanol (polyoxyl lauryl ether; Aethoxysklerol, Asclera, Varithena) is a non-ionic surfactant sclerosant used in liquid and foam form to treat varicose veins, spider veins, and hemorrhoids by destroying venous endothelium.
Poliedro de Caracas
Poliedro de Caracas: multi-purpose geodesic-dome arena in La Rinconada, Caracas, Venezuela, also called El Domo Geodésico de La Rinconada. Designed by Jimmy Alcock with Buckminster Fuller engineering, inaugurated March 1974 with Foreman–Norton boxing; capacity about 13,500 seated, up to 20,000.
Poligar system
The Poligar system (பாளையக்காரர் முறை) was a Tamil system of military chieftainship, traditionally attributed to Visvanatha Nayak of Madura and abolished by the East India Company in 1801.
Poliglecaprone 25
Poliglecaprone 25 (Monocryl, Ethicon, 1993) is a synthetic absorbable monofilament suture of glycolide and epsilon-caprolactone for soft tissue and subcuticular closure, retaining about 30% strength at 2 weeks and fully absorbing in 91-119 days.
Polignac's conjecture
Polignac's conjecture, stated by Alphonse de Polignac in 1849, claims every even number occurs infinitely often as a difference between consecutive primes; its gap-2 case is the twin prime conjecture.
Poligon
Полигон (Russian for polygon/range): a bounded tract for military training, weapons testing, waste disposal, field research, or tactical games; also a GIS area feature. Examples include Kubinka tank proving ground, Moscow lasertag bases, and OSM polygons.
Polihexanide
Polihexanide (polyhexamethylene biguanide, PHMB) is a cationic biguanide polymer antiseptic active against bacteria, fungi, parasites, and viruses; it is the active substance of Akantior, the first EU-authorized medicine for Acanthamoeba keratitis (2024).
Polik-mana Mons
Polik-mana Mons is a 600-km-diameter shield volcano at 24.5 N, 264 E in Asteria Regio, Venus, named in 1997 for a Hopi butterfly maiden kachina and tied to the Hecate-Latona Chasma rift.
Polikarpov I-16
The Polikarpov I-16 was a Soviet single-seat fighter designed by Nikolai Polikarpov and the first monoplane fighter with an enclosed cockpit and retractable gear, serving from 1935 to 1943.
Polikarpov Po-2 (По-2)
The Polikarpov Po-2 (По-2), designed by Nikolai Polikarpov, was a Soviet two-seat biplane trainer first flown in 1928 as the U-2, with over 33,000 built.
Polina Anikeeva
Polina Anikeeva is a materials scientist at MIT who develops flexible neural probes and wireless methods for controlling neurons, and heads MIT's materials science department since 2024.
Polina Astakhova
Polina Astakhova (Поліна Григорівна Астахова), 1936–2005, was a Soviet artistic gymnast from Ukraine who won ten Olympic medals, five golds, and was twice uneven bars champion.
Polina Bayvel
Polina Bayvel is a British professor of optical communications and networks at University College London who founded the Optical Networks Group in 1994 and set multiple fiber-capacity records.
Polina Gagarina (Полина Сергеевна Гагарина)
Polina Sergeevna Gagarina (Полина Сергеевна Гагарина), Russian pop singer born 1987 in Moscow; Star Factory winner 2003, Eurovision 2015 runner-up with "A Million Voices" (303 points), The Singer China 2019 finalist, coach on Golos.
Polina Iatcenko
Polina Iatcenko, Russian tennis player born 2003 in Murmansk, based in Minsk. WTA 125 singles champion (Caldas da Rainha 2025), 2026 Mumbai doubles winner, 2026 US Open second round, career-high No.138.
Polina Komar
Polina Dmitriyevna Komar (Полина Дмитриевна Комар), born 1999 in Moscow, is a Russian artistic swimmer, Tokyo 2020 Olympic team gold medalist for ROC, five-time world and three-time European champion, retired 2021.
Polina Kuznetsova
Polina Kuznetsova is a Russian handball player who plays left wing and won Olympic gold with Russia at Rio 2016 and silver with the ROC at Tokyo 2020.
Polio
Polio (poliomyelitis), caused by poliovirus, a paralytic disease of children; IPV (Salk, 1955) and OPV (Sabin) vaccines cut cases over 99% since 1988; only wild type 1 remains, endemic in Afghanistan and Pakistan.
Polio eradication
Polio eradication: the GPEI (since 1988) campaign to eliminate wild poliovirus types 1–3 and vaccine-derived outbreaks; WPV2 and WPV3 certified eradicated, WPV1 endemic only in Afghanistan and Pakistan, with cVDPV2 outbreaks managed using nOPV2.
Polio eradication in Nigeria
Polio eradication in Nigeria is the national component of the Global Polio Eradication Initiative. Nigeria's last wild polio case was in 2016, though vaccine-derived poliovirus continues to circulate.
Polio vaccine
Polio vaccine: IPV (Salk, licensed 12 April 1955) and OPV (Sabin, 1961–1963) protect against poliomyelitis; IPV-only in the US since 2000, wild types 2 and 3 eradicated, type 1 endemic in Pakistan and Afghanistan.
Poliocephalus
Poliocephalus (Selby, 1840) is a genus of two Southern Hemisphere grebes in Podicipedidae: the hoary-headed grebe of Australia and Tasmania and the Near Threatened New Zealand grebe of the North Island.
Poliochne
Poliochne (Poliochni, Πολιόχνη), prehistoric settlement on east Lemnos at Vroskopos near Kaminia; excavated 1930-36 by the Italian School; inhabited mid-4th to end 3rd millennium BC, called earliest town in Europe.