All articles starting with P
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PRDX6
PRDX6 (peroxiredoxin 6, also 1-Cys, AOP2, aiPLA2) is the only mammalian 1-Cys peroxiredoxin, a bifunctional 25-kDa enzyme with GSH peroxidase and phospholipase A2 activities, highly expressed in lung and implicated in cancer progression and chemoresistance.
Pre emption zone
Pre-emption zone (pre-emptive rights zone): a designated land area where a beneficiary, historically a settler on public domain and today usually a public body, holds a right of first refusal to buy property, as in France's ZAD and DPU zones and German municipal zones.
Pre-Adamite
Pre-Adamite, or Pre-Adamism, is the belief that humans existed before Adam, the first man of Genesis. Isaac de La Peyrère's 1655 book was burned in Paris.
Pre-Analytical Phase
Pre-analytical phase (pre-examination phase): all laboratory testing steps from test ordering through patient preparation, sample collection, transport, and preparation before analysis; source of 60-70% of laboratory errors, led by hemolysis.
Pre-Angkorian inscriptions of Sambor Prei Kuk
The Pre-Angkorian inscriptions of Sambor Prei Kuk (សិលាចារឹកសម្បូរព្រៃគុហ៍) are seventh-century Sanskrit and Old Khmer inscriptions recording the religious foundations of the Chenla kings, chiefly Isanavarman I.
Pre-Code Hollywood
Pre-Code Hollywood, 1930-1934, also called the era before Hays Code enforcement, covers American sound films made while the Production Code lacked strong enforcement; characterized by frank treatment of sex, crime, and race until the PCA took over in July 1934.
Pre-Columbian era
The Pre-Columbian era is the period in the Americas before European arrival, ending with Columbus's 1492 landfall. It spans peopling of the Americas over 20,000 years ago and civilizations including the Olmec, Maya, Aztec, and Inka.
Pre-Conception and Pre-Natal Diagnostic Techniques Act, 1994
Indian law, Act No. 57 of 1994, also called the PCPNDT Act, banning foetal sex determination and sex selection before or after conception; regulates ultrasound clinics, sets penalties up to 5 years, and is enforced by Appropriate Authorities rather than police.
Pre-control (quality control)
Pre-control is a statistical process control technique that divides specification tolerance into colored zones operators use to adjust processes, developed in the 1950s by Rath and Strong.
Pre-Descemet corneal dystrophy
Pre-Descemet corneal dystrophy (PDCD), including punctiform and polychromatic PPPCD, is a rare inherited stromal corneal dystrophy with deep stromal opacities anterior to Descemet membrane, asymptomatic, PRDX3-linked, good prognosis.
Pre-dreadnought battleship
A pre-dreadnought battleship is a battleship built between roughly 1890 and 1905, carrying four heavy guns plus medium batteries, until HMS Dreadnought made the type obsolete in 1906.
Pre-eclampsia
Pre-eclampsia, a hypertensive multi-organ disorder of pregnancy after 20 weeks (hypertension plus proteinuria), affects 3-8% of births; managed with aspirin prophylaxis, magnesium sulfate, and delivery.
Pre-eclampsia superimposed on chronic hypertension
Pre-eclampsia superimposed on chronic hypertension (superimposed preeclampsia) is preeclampsia developing in a woman with hypertension before pregnancy or before 20 weeks, affecting roughly 20–25% of such pregnancies, harder to diagnose, and linked to worse maternal outcomes.
Pre-ejaculate
Pre-ejaculate (pre-cum, Cowper's fluid) is clear fluid released from the penis during arousal by the bulbourethral glands; it neutralizes urethral acidity, may contain sperm, and affects withdrawal-method contraception and HIV/STI risk.
Pre-engagement ring
Pre-engagement ring, also called a promise or friendship ring, is jewelry given before a proposal to signal commitment and intended marriage, worn usually on the right hand, with 16th-century European roots.
Pre-excitation syndrome
Pre-excitation syndrome, chiefly Wolff-Parkinson-White (WPW), is a cardiac condition where an accessory pathway bypasses the AV node, causing early ventricular activation, delta waves, AVRT, and risk of pre-excited atrial fibrillation; curable by catheter ablation.
PRE-EXELUCA trial
PRE-EXELUCA (NCT06215326) is a randomized controlled trial by Guangdong Provincial People's Hospital comparing intensities of preoperative exercise training in 100 moderate-to-high perioperative risk lung cancer patients before lung resection, measuring cardiopulmonary function and postoperative outcomes.
Pre-existence
Pre-existence, also called the pre-mortal life, is the doctrine that the human soul existed before its mortal birth, defended by Plato, Origen, and Latter-day Saints.
Pre-exponential factor
The pre-exponential factor, also called the frequency factor or Arrhenius A factor, is the constant A in the Arrhenius equation that represents the frequency of collisions between reactant molecules.
Pre-exposure prophylaxis
Pre-exposure prophylaxis (PrEP) is antiretroviral medicine taken by HIV-negative people to prevent HIV, about 99% effective against sexual transmission when taken as prescribed. Options include daily Truvada, Descovy, injectable cabotegravir, and twice-yearly lenacapavir.
Pre-Greek substrate
Pre-Greek substrate: the unattested language of Greece and the Aegean before Greek, known only through loanwords in Ancient Greek lacking Indo-European etymology; studied over 120 years under Pelasgian, Anatolian-Luwian, Aegean (Beekes), and Kartvelian theories.
Pre-Hispanic City and National Park of Palenque
The Pre-Hispanic City and National Park of Palenque is a UNESCO World Heritage Site in Chiapas, Mexico, a major Maya city at its peak from AD 500 to 700.
Pre-ignition
Pre-ignition is the uncontrolled ignition of the fuel-air mixture in a spark-ignition engine by a hot surface before the spark plug fires, distinct from knock; its low-speed form, LSPI, damages pistons in turbocharged engines.
Pre-Indo-European languages
Pre-Indo-European languages are the languages of Europe and Anatolia before the Indo-European dispersal from the third millennium BCE, known mostly through substrates, plus survivors like Basque and attested Etruscan, Minoan, and Hattic.
Pre-Islamic Arabia
Pre-Islamic Arabia (al-jahiliyya in Islamic tradition): the peninsula before the 7th-century rise of Islam, with kingdoms such as Saba, Himyar, and the Nabataeans, tens of thousands of inscriptions, and diverse languages and religions.
Pre-Islamic Arabic poetry
Pre-Islamic Arabic poetry (al-shiʿr al-jāhilī) is the earliest Arabic literary corpus, chiefly monorhymed qaṣīda odes such as the Muʿallaqāt, transmitted through Muslim-era collections, debated for authenticity, and foundational to Classical Arabic and Quranic studies.
Pre-Kerma
Pre-Kerma is a settlement phase and archaeological culture at Kerma in Upper Nubia, Sudan, dated 3500–2500 BC, discovered in 1986 and ancestral to the Kerma kingdom.
Pre-kindergarten
Pre-kindergarten, or pre-K, is preprimary classroom education for children typically ages 3 to 4 who have not yet entered kindergarten, often state-funded in the United States.
Pre-lithiation
Pre-lithiation is a battery manufacturing technique that adds extra active lithium to a lithium-ion cell, compensating for lithium irreversibly lost during the first charge and early cycling.
Pre-main-sequence star
A pre-main-sequence star is a young star that shines by gravitational contraction before hydrogen fusion begins in its core; low-mass examples are seen as T Tauri stars.