All articles starting with P
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Perth, Scotland
Perth, Scotland: the Fair City on the River Tay, granted city status in 2012 as Scotland's seventh city, a UNESCO City of Crafts and Folk Art, home of the Stone of Destiny at Perth Museum.
Perthshire
Perthshire (Siorrachd Pheairt), formally County of Perth, a historic county of central Scotland straddling the Highland Line; sheriffdom by the 12th century, county council 1890-1975, now mostly Perth and Kinross; county town Perth, county top Ben Lawers.
Pertinax
Pertinax (Publius Helvius Pertinax, 126-193) was a Roman emperor of the Year of the Five Emperors: a freedman's son, grammar teacher, and distinguished general under Marcus Aurelius who ruled 86 days in 193 before Praetorians killed him.
Pertti J. Neuvonen
Pertti J. Neuvonen, full name Pertti Jaakko Neuvonen (1943–2020), was a Finnish professor of clinical pharmacology at Helsinki who identified over 200 drug–drug interactions and showed P450 inhibition can raise drug concentrations more than tenfold.
Pertti Karppinen
Pertti Karppinen (born 1953), Finnish rower, won Olympic single sculls gold at three consecutive Games (1976, 1980, 1984), matched only by Vyacheslav Ivanov; also World Champion 1979 and 1985, famed for his rivalry with Peter-Michael Kolbe.
Pertti Teurajarvi
Pertti Teurajärvi (Pertti Benjamin Teurajärvi), Finnish cross-country skier born 1951 in Kolari; won 4×10 km relay gold at the 1976 Innsbruck Olympics, relay silver at Lahti 1978, and relay bronze at Lake Placid 1980; nephew of Eero Mäntyranta.
Perturb and observe algorithm
The perturb and observe (P&O) algorithm, also called hill climbing, is the most commonly used maximum power point tracking method for photovoltaic arrays, adjusting voltage to maximize power.
Perturbation (astronomy)
A perturbation, also called an orbital or gravitational perturbation, is a deviation of an orbit from the ideal Keplerian ellipse, caused by third bodies and other forces.
Perturbation screen
A perturbation screen systematically disrupts genes in a cell population, by CRISPR editing or RNA interference, and measures the resulting phenotypes to infer what each gene does.
Perturbation theory
Perturbation theory, also called perturbation analysis, is a group of methods for approximating hard mathematical and physical problems by starting from a related exactly solvable one.
Perturbation theory (quantum mechanics)
Perturbation theory in quantum mechanics, also called Rayleigh–Schrödinger perturbation theory, is a family of approximation methods for energy levels and states of nearly solvable systems.
Perturbative string gravity
Perturbative string gravity is the body of results showing that quantum gravity emerges automatically from string theory, whose closed strings contain a massless spin-2 graviton and whose consistency conditions reproduce Einstein's equations.
Perturbator
Perturbator, aka James Kent (born 1993, Paris), is a French darksynth producer active since 2012, known for Dangerous Days, the Hotline Miami OSTs, and the 2025 album Age of Aquarius on Nuclear Blast.
Perturbed angular correlation
Perturbed angular correlation (PAC) is a nuclear spectroscopy method that uses coincidence counting of cascade gamma rays to measure hyperfine interactions, applied mainly in condensed matter research.
Perturbed parameter ensemble
A perturbed parameter ensemble, or perturbed physics ensemble, is a climate modeling method that runs one model many times with varied parameter values to sample uncertainty.
Pertuzumab
Pertuzumab (Perjeta, formerly 2C4/Omnitarg) is a humanized monoclonal antibody, the first HER2 dimerization inhibitor, approved in 2012 with trastuzumab and docetaxel for HER2-positive metastatic breast cancer, later adjuvant and neoadjuvant.
Pertuzumab/trastuzumab regimen
The pertuzumab/trastuzumab regimen is a dual HER2-targeted antibody combination, usually given with chemotherapy or endocrine therapy, used to treat HER2-positive breast cancer in metastatic, neoadjuvant, and adjuvant settings, first FDA-approved in 2012.
Peru
Peru (Perú, Piruw), a Pacific-coast South American republic spanning coast, Andes, and Amazon. Population 34.6 million (2025), GDP US$334.85 billion, mining about 10% of GDP; Keiko Fujimori became president in July 2026 after a razor-thin runoff.
Peru Basin
Peru Basin (Peruanisches Becken, Peruvian Basin): abyssal plain in the southeastern Pacific off Peru, 4,000-4,400 m deep, bounded by the Carnegie and Nazca Ridges, rich in manganese nodules and site of the 1989 DISCOL deep-sea mining disturbance experiment.
Peru LNG Gas Pipeline
The Peru LNG gas pipeline is a 408-kilometer pipeline carrying Camisea gas from the Andean highlands to the Pampa Melchorita liquefaction plant on Peru's Pacific coast.
Peru LNG Terminal
The Peru LNG Terminal at Pampa Melchorita, Peru, loads liquefied natural gas from the Camisea fields onto tankers and is South America's first LNG export facility.
Peru national football team
Peru national football team (Selección de fútbol del Perú), men's team of the Peruvian Football Association in CONMEBOL; two-time Copa América champion (1939, 1975), FIFA rank 50th as of July 2026, coach Mano Menezes.
Peru Two
The Peru Two, Michaella McCollum and Melissa Reid, were arrested at Lima airport in 2013 with 11 kg of cocaine, jailed for six years and eight months, and released in 2016.
Peru-nefer
Peru-nefer (Prw-nfr) was a naval base and palace precinct of Egypt's New Kingdom under Thutmose III and Amenhotep II, long identified with Tell el-Dab'a, ancient Avaris, in the eastern Nile Delta.
Peru–Bolivian Confederation
The Peru–Bolivian Confederation (Confederación Perú-Boliviana) was a short-lived union of Bolivia and two Peruvian states, created by Andrés de Santa Cruz in 1836 and destroyed by a Chilean-led invasion in 1839.
Peru–Chile Trench
Chile Trench (Peru–Chile Trench): 6,000-km oceanic trench off Chile and Peru where the Nazca Plate subducts beneath South America; Atacama Trench section exceeds 8,000 m depth; source of the 1960 Valdivia M9 earthquake.
Perugia
Perugia, Italian city and capital of Umbria, ancient Etruscan Perusna and later Augusta Perusia, home to the University of Perugia founded by papal bull in 1308.
Perumal Tirumoli
Perumal Tirumoli (பெருமாள் திருமொழி, "the sacred words of the Lord") is a ninth-century Tamil bhakti work by Kulasekara Alvar of 105 verses in ten decades praising Vishnu.
Perumbidugu Mutharaiyar
Perumbidugu Mutharaiyar (பெரும்பிடுகு முதரையர்), also called Suvaran Maran, was a Mutharaiyar king who ruled central Tamil Nadu from 705 to 745 as a Pallava feudatory.
Perumpanarruppatai
Perumpanarruppadai (பெரும்பாணாற்றுப்படை) is a 500-line Sangam Tamil poem, the fourth of the Pattuppattu Ten Idylls, in which a bard guides a poor fellow bard to his patron, the Kanchi king Tondaiman Ilanthiraiyan.