All articles starting with P
28,818 articles
PhytoPath
PhytoPath (phytopathdb.org) is a plant pathogen genomics database launched in 2012, integrating Ensembl genome browsers with PHI-base curated mutant phenotypes for 32 fungal, 14 protist, and 12 bacterial species.
Phytopathologists: founders and shapers of the discipline
Phytopathologists, founders and shapers of plant pathology: from 18th-century fungal studies and Koch's postulates to the 1884 AAAS committee, USDA mycology under Lamson-Scribner, Shear's 1908 APS founding, and the journals Phytopathology and Plant Disease.
Phytophotodermatitis
Phytophotodermatitis, also called lime disease, is a non-immunologic phototoxic skin reaction caused by furocoumarins (psoralens) from plants such as limes, figs, hogweed, and celery, activated by UVA sunlight, causing streaky blisters and lasting hyperpigmentation.
Phytophthora
Phytophthora, oomycete plant pathogen genus (not a fungus), soilborne and waterborne, causing sudden oak death, kauri dieback, root rots, and citrus and potato diseases; Clade 7a is its largest subclade with 34 taxa.
Phytophthora infestans
Phytophthora infestans, the potato and tomato late blight oomycete, not a true fungus. 5-day life cycles, oospores and clonal lineages from FAM-1 and US-1 to today's dominant EU36_A2, €5+ billion annual losses.
Phytophthora ramorum
Phytophthora ramorum (sudden oak death pathogen, ramorum blight) is an oomycete in clade 8c with four clonal lineages (NA1, NA2, EU1, EU2), over 170 hosts, introduced via nursery trade to California, Oregon, and Europe.
Phytoplankton
Phytoplankton (microalgae) are microscopic drifting photosynthetic organisms in fresh and salt water, including cyanobacteria, diatoms, dinoflagellates, and coccolithophores; they produce about half of Earth's oxygen and pump roughly 10 gigatonnes of carbon yearly into the deep ocean.
Phytoplasma
Phytoplasma ('Candidatus Phytoplasma') are wall-less, uncultured Mollicutes bacteria living in plant phloem, vectored by leafhoppers, planthoppers, and psyllids, causing witches' broom, phyllody, and yellows in over 700 plant species.
Phytoremediation
Phytoremediation, also called green remediation, uses plants and their root microbes to remove or stabilize contaminants in soil and water, best suited to shallow, low to moderate contamination.
Phytoseiidae
Phytoseiidae, phytoseiid or predatory mites (Mesostigmata), a family of small mites that prey on spider mites, thrips, and pollen; key biocontrol agents including Phytoseiulus persimilis, with about 2,700 valid species in three subfamilies.
Phytoseiulus
Phytoseiulus is a genus of small predatory mites in the family Phytoseiidae, containing four species that specialize in preying on web-spinning Tetranychus spider mites, with P. persimilis now cosmopolitan.
Phytosome
A phytosome, also called a phyto-phospholipid complex or herbosome, is a delivery system that binds plant-derived actives to phosphatidylcholine to improve absorption, patented by Indena in 1989.
Phytosphingosine
Phytosphingosine is a long-chain sphingoid base with formula C18H39NO3, found mainly in fungi and plants and abundant in human skin ceramides, used in cosmetics for antimicrobial and anti-inflammatory effects.
Phytosterol
Phytosterols, also called plant sterols, are plant compounds resembling cholesterol, found in vegetable oils, nuts, and cereals, that lower blood cholesterol by blocking its intestinal absorption.
Phytosterol biosynthesis pathway
The phytosterol biosynthesis pathway is the plant-specific series of ER-localized reactions converting cycloartenol into β-sitosterol, stigmasterol, and campesterol, and into cholesterol and brassinosteroid precursor branches.
Phytotoxicity
Phytotoxicity, also called plant chemical injury, is the toxic effect of substances such as herbicides, pesticides, immature compost, or allelochemicals on plants, causing germination inhibition, chlorosis, necrosis, and stunted growth, measured by germination index bioassays and OECD plant tests.
Pi
Pi, also known as Archimedes' constant, is the ratio of a circle's circumference to its diameter, an irrational number equal to about 3.14159 whose digits continue without end.
Pi (film)
Pi (π) is Darren Aronofsky's 1998 black-and-white debut thriller starring Sean Gullette as mathematician Max Cohen, who seeks a 216-digit number linking stock market patterns and God's name; made for about $60,000, it won Sundance's Directing Award and grossed $3.2 million.
Pi (Inflection)
Pi is a conversational AI chatbot built by Inflection AI and released in May 2023, designed as a kind, supportive companion; it reached a million daily users before its founding team joined Microsoft in 2024.
Pi (letter)
Pi (πι; Π, π) is the 16th Greek letter, sounding /p/ and pronounced /paɪ/. It derives from Phoenician pe (mouth), became the Latin P, and its lowercase form has denoted the circle constant 3.14159 since William Jones in 1706.
Pi Aquarii
Pi Aquarii is a bright classical Be star of spectral type B1III-IVe in Aquarius, one half of an 84.1-day binary with a probable white dwarf companion and a source of hard, variable X-ray emission.
Pi backbonding
Pi backbonding, also called back-donation, is the donation of electron density from a filled metal d orbital into an empty antibonding orbital of a ligand such as carbon monoxide.
Pi Beta Phi
Pi Beta Phi (Pi Phi), founded April 28, 1867 as I.C. Sorosis at Monmouth College, is the first national women's fraternity, an NPC founding member with 350,000+ initiated members and the Read > Lead > Achieve literacy philanthropy.
Pi bond
A pi bond (π bond) is a covalent bond formed by side-by-side overlap of p orbitals on adjacent atoms, forming the second bond of double bonds and triple bonds.
Pi calculus
The pi calculus is a process calculus for concurrent systems in which communication links are names that can be created dynamically and passed as messages, modeling changing structure.
PI controller
A PI controller, or proportional-integral controller, is a two-term feedback controller that sums proportional and integral action, driving steady-state error to zero in process control.
Pi Datacenters
Pi Datacenters is an Indian enterprise data center and cloud services provider founded in 2014 by Kalyan Muppaneni, headquartered in Amaravati, Andhra Pradesh, and known for its Tier IV certified Pi Amaravati campus.
Pi Day
Pi Day, March 14 (3/14), celebrates the mathematical constant pi (π). Founded 1988 by physicist Larry Shaw at San Francisco's Exploratorium, recognized by the US House in 2009, and the date of UNESCO's International Day of Mathematics.
Pi Kappa Alpha (ΠΚΑ)
Pi Kappa Alpha (ΠΚΑ, PIKE) is an international men's social fraternity founded March 1, 1868 at the University of Virginia. Distinct from Pi Kappa Phi and Kappa Alpha Order; 310,000+ initiates, Memphis headquarters, garnet and gold colors.
Pi Kappa Phi
Pi Kappa Phi (ΠΚΦ), a men's social fraternity founded December 10, 1904 at the College of Charleston by Kroeg, Fogarty, and Mixson; distinct from Phi Kappa Phi honor society; runs The Ability Experience philanthropy.