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Passivity and complete passivity
Passivity and complete passivity are properties of quantum states defined by work extraction: a passive state yields no work to any cyclic unitary process, and complete passivity extends this to all copies.
Past
The past is the portion of time that has already gone by, measured by calendars and clocks, and named in grammar by the tense for earlier action.
Past hypothesis
The Past Hypothesis is the posit that the universe began in a very low-entropy macrostate, grounding the thermodynamic arrow of time; David Albert named it in 2000.
Pasteur Institute
The Pasteur Institute (Institut Pasteur) is a private French biomedical research foundation in Paris, founded by Louis Pasteur in 1887 to treat rabies and study infectious diseases.
Pasteur's swan-neck flask experiment
Pasteur's swan-neck flask experiment was a series of demonstrations by Louis Pasteur between 1859 and 1861 in which broth in curved-neck flasks stayed sterile while exchanging air, refuting spontaneous generation.
Patch-seq
Patch-seq is a laboratory technique that combines whole-cell patch-clamp recording with single-cell RNA sequencing to measure the electrophysiology, morphology, and gene expression of the same individual neuron.
Patchy particles
Patchy particles are colloidal particles patterned with a small, fixed number of attractive patches, giving directional bonding and limited valence that control how they self-assemble.
Paternò–Büchi reaction
The Paternò–Büchi reaction is a photochemical [2 + 2] cycloaddition of an excited carbonyl compound with an alkene to form an oxetane, first reported by Emanuele Paternò in 1909.
Path (graph theory)
In graph theory, a path is a walk in a graph that repeats no vertex and therefore no edge; a graph is connected when every pair of vertices has a path between them.
Path analysis (statistics)
Path analysis is a statistical method that decomposes correlations between variables into direct and indirect causal effects, estimated through simultaneous regression equations drawn as path diagrams.
Path decomposition
A path decomposition is a graph decomposition whose bags form a path; the minimum width over all such decompositions is the graph's pathwidth, the path-like analog of treewidth.
Path dependence of work
Path dependence of work is the principle in mechanics that work done by a force depends on the route taken, not just the start and end points.
Path graph
A path graph is a graph consisting of a single chain of vertices connected end-to-end, with no branches or cycles; the path on n vertices is written P_n.
Path integral formulation
The path integral formulation, also called the sum over histories, is a formulation of quantum mechanics, published by Richard Feynman in 1948, that sums a contribution from every path a particle can take.
Path integral molecular dynamics
Path integral molecular dynamics (PIMD) is a computer simulation method for equilibrium quantum properties, representing each particle as a ring polymer of beads joined by harmonic springs.
Path integral Monte Carlo
Path integral Monte Carlo is a quantum Monte Carlo method that computes finite-temperature properties of interacting quantum many-body systems by sampling particle paths in imaginary time.
Path-connected space
A path-connected space is a topological space in which any two points can be joined by a continuous path. Every path-connected space is connected, but the converse fails.
Pathological science
Pathological science is the practice of producing scientific claims for effects that do not exist, through self-deception rather than fraud, as defined by Nobel laureate Irving Langmuir in 1953.
Patience Mthunzi
Patience Mthunzi-Kufa is a South African laser scientist who pioneered biophotonics in South Africa, earning the country's first known PhD in the field in 2010.
Patina
Patina is a surface layer that forms on a material through atmospheric exposure, moisture, or use, most familiar as the green film on copper and bronze.
Patrice Genevet
Patrice Genevet is a French optical physicist known for his work on metasurfaces, and has been Professor of Physics at the Colorado School of Mines since 2023.
Patricia Burchat
Patricia Burchat is an experimental particle physicist at Stanford University known for the BaBar CP violation experiment and dark energy research with the Rubin Observatory.
Patricia Dalyander
Patricia ("Soupy") Dalyander is an American physical oceanographer known for modeling how waves and currents move sand, oil, and barrier islands along the Gulf of Mexico coast, and a 2019 PECASE recipient.
Patricia Dove
Patricia M. Dove is an American geochemist at Virginia Tech, a University Distinguished Professor who studies biomineralization and was elected to the National Academy of Sciences in 2012.
Patrick A. Lee
Patrick A. Lee, also known as Patrick Lee, is an American condensed matter theorist, MIT professor since 1982, and pioneer of mesoscopic physics and high-temperature superconductivity theory.
Patrick Couvreur
Patrick Couvreur, born in 1950, is a pharmaceutical scientist and professor emeritus at Université Paris-Saclay known for inventing biodegradable drug-delivery nanoparticles and squalenoylation, and for winning the 2013 European Inventor Award.
Patrick Dehornoy
Patrick Dehornoy was a French mathematician, professor at the Université de Caen, who proved in 1992 that Artin's braid groups are left-orderable, constructing the Dehornoy ordering; he died in 2019.
Patrick du Val
Patrick du Val (1903–1987) was a British mathematician who worked on algebraic surfaces and classified the surface singularities now known as du Val singularities in 1934.
Patrick G. Hatcher
Patrick G. Hatcher (P.G. Hatcher) is an American organic geochemist, Batten Endowed Chair at Old Dominion University since 2006, known for his 1983 Nature paper on petroleum-forming kerogen.
Patrick Gill (British physicist)
Patrick Gill is a British physicist and NPL Fellow at the National Physical Laboratory in Teddington, known for optical atomic clocks that underpin a future redefinition of the SI second.