All articles starting with P
28,818 articles
P versus NP problem
The P versus NP problem asks whether every problem whose solutions can be checked quickly can also be solved quickly, one of the Clay Mathematics Institute's $1 million Millennium Prize Problems.
P wave
The P wave, or primary wave, is the fastest seismic wave an earthquake produces, compressing rock parallel to its direction of travel and arriving first at seismic stations.
P wave (electrocardiography)
P wave (electrocardiography): first positive ECG deflection, representing atrial depolarization; named P by Einthoven. Normal duration under 120 ms, amplitude under 2.5 mm in limb leads, axis 0 to +75 degrees.
P-15 Termit (П-15 «Термит»)
The P-15 Termit (П-15 «Термит», NATO reporting name SS-N-2 Styx) is a Soviet sea-skimming anti-ship cruise missile developed by Raduga and adopted by the Soviet Navy in 1960.
P-270 Moskit
The P-270 Moskit (П-270 «Москит»), known in the West as the SS-N-22 "Sunburn", is a Soviet supersonic ramjet anti-ship cruise missile developed by MKB Raduga and in service since 1984.
P-38 can opener
The P-38 can opener, nicknamed the John Wayne by Marines, is a small folding can opener invented in 1942 and issued with Army field rations through the 1980s.
P-500 Bazalt
The P-500 Bazalt (П-500 «Базальт»), NATO name SS-N-12 Sandbox, is a Soviet supersonic anti-ship cruise missile developed by Chelomey's bureau, operational since 1975, and still carried by Russian Navy warships.
P-700 Granit
The P-700 Granit, NATO name SS-N-19 Shipwreck, is a Soviet and Russian supersonic anti-ship cruise missile that entered service in 1983 to attack carrier battle groups with coordinated salvos.
P-800 Oniks (Оникс)
The P-800 Oniks (Оникс), also called Yakhont and SS-N-26 Strobile, is a Russian supersonic anti-ship cruise missile with about 300 km range, in service since 2002.
P-90
P-90: Gibson's single-coil electric guitar pickup, introduced 1946 by Walter Fuller; wide flat coil, two Alnico bar magnets, six pole screws; Gibson's premium pickup until the 1955 humbucker; dogear and soapbar formats.
P-adic analysis
P-adic analysis, also known as ultrametric calculus, is the branch of analysis over the p-adic number fields, created by Kurt Hensel around 1899 and central to modern number theory.
P-adic exponential function
The p-adic exponential is the classical exponential power series interpreted over the p-adic numbers, where it converges only on a small disk around the origin, unlike the real exponential.
p-adic field
A p-adic field, also called a p-adic local field, is a field that is a finite extension of the p-adic numbers for a prime p, studied in algebraic number theory.
P-adic Hodge theory
P-adic Hodge theory is a branch of arithmetic geometry that compares the p-adic cohomology theories, étale, de Rham, and crystalline, of algebraic varieties over p-adic fields.
p-adic integer
A p-adic integer is an element of the ring Z_p, written in base p with digits extending infinitely to the left; it completes the ordinary integers under the p-adic norm.
P-adic L-function
A p-adic L-function is a p-adically valued analytic function that interpolates special values of classical L-functions such as the Riemann zeta function, introduced by Kubota and Leopoldt in 1964.
P-adic number
A p-adic number, or p-adic, is a number obtained by completing the rational numbers with a distance based on divisibility by a prime p, introduced by Kurt Hensel in 1897.
p-adic numbers
The p-adic numbers are a family of number systems, one for each prime p, built by completing the rational numbers; introduced by Kurt Hensel in 1897.
P-adic valuation
The p-adic valuation, also called the p-adic order, measures how deeply a rational number is divisible by a fixed prime p, taking the value infinity at 0.
p-Aminohippuric acid
p-Aminohippuric acid (PAH) is a synthetic organic anion that the kidneys clear almost completely in one pass, making its clearance the classic nonradioactive measure of effective renal plasma flow.
P-chart
The p-chart is an attribute control chart in statistical process control that monitors the proportion of defective units in samples of varying size, using binomial control limits.
P-Chiral phosphine
A P-chiral phosphine, also called a P-stereogenic phosphine, is an organophosphorus compound whose stereogenic center is the trivalent phosphorus atom itself, used mainly as a chiral ligand in asymmetric catalysis.
P-code machine
A P-code machine is a hypothetical stack-based virtual machine whose P-code instruction set was created at ETH Zurich in the 1970s so Pascal compilers could emit portable intermediate code.
P-complete
A P-complete problem is a decision problem in P to which every other problem in P reduces under NC reductions; if any such problem had an efficient parallel algorithm, then NC equals P.
p-Coumaric acid
p-Coumaric acid, also known as 4-hydroxycinnamic acid, is a hydroxycinnamic acid found in edible plants and a key intermediate of the phenylpropanoid pathway, with antioxidant and antimicrobial uses in food preservation.
P-curve
P-curve is a meta-analytic technique introduced by Simonsohn, Nelson, and Simmons in 2013 that examines the distribution of significant p-values across studies to detect evidential value or selective reporting, though recent critiques recommend against its use.
p-Cymene
p-Cymene, also called p-cymol, is an aromatic hydrocarbon with the formula C₁₀H₁₄ that occurs in essential oils of thyme and oregano and is used industrially as a solvent.
P-Delta effect
The P-Delta effect is a geometric nonlinearity in which gravity loads on a laterally displaced structure produce extra moments and displacements that can destabilize it.
P-glycoprotein
P-glycoprotein (P-gp, ABCB1, MDR1), a 170-kDa ATP-dependent efflux transporter discovered in 1976, pumps structurally diverse drugs out of cells, causes cancer multidrug resistance, guards the blood-brain barrier, and has no approved clinical inhibitor.
P-group
A p-group, also called a primary group, is a group whose every element has order a power of a fixed prime p, central to finite group theory.