All articles starting with P

Posterior contraction rates and Bernstein–von Mises phenomena in nonparametric Bayes

Posterior contraction rates and Bernstein–von Mises phenomena in nonparametric Bayes measure how fast posteriors concentrate around the truth and whether they become Gaussian, which depends on the norm used.

Posterior cortical atrophy

Posterior cortical atrophy (Benson's syndrome) is a rare young-onset dementia syndrome of visuospatial and perceptual decline from parieto-occipital atrophy, usually caused by Alzheimer's disease pathology.

Posterior cruciate ligament

Posterior cruciate ligament (PCL): strongest knee ligament, behind the ACL, primary restraint to posterior tibial translation; two bundles, injured by dashboard or fall on bent knee, often treated nonoperatively.

Posterior cruciate ligament reconstruction

Posterior cruciate ligament reconstruction is a surgical procedure that replaces a torn PCL, the knee's largest intra-articular ligament, with a tendon graft to restore posterior knee stability.

Posterior dislocation of hip

Posterior dislocation of hip: backward displacement of the femoral head from the acetabulum, about 90% of hip dislocations, usually from dashboard-type trauma; emergency closed reduction, risks avascular necrosis, arthritis, sciatic nerve injury.

Posterior ischemic optic neuropathy

Posterior ischemic optic neuropathy (PION), also called retrobulbar ischemic optic neuropathy, is sudden painless vision loss from ischemia of the posterior optic nerve with a normal initial fundus. Three subtypes: non-arteritic, arteritic (giant cell arteritis), and perioperative, most often after spine surgery.

Posterior lumbar interbody fusion

Posterior lumbar interbody fusion (PLIF) is a spinal operation that stabilizes a painful lumbar segment by removing the disc and packing the space with bone graft in bilateral cages.

Posterior pituitary

Posterior pituitary (neurohypophysis): neural posterior lobe of the pituitary gland, derived from hypothalamic downgrowth, storing and releasing hypothalamic vasopressin and oxytocin into the circulation.

Posterior polymorphous corneal dystrophy

Posterior polymorphous corneal dystrophy (PPCD, Schlichting dystrophy) is a rare autosomal dominant corneal endothelial dystrophy with vesicular, band-like, and diffuse Descemet membrane opacities, subtypes PPCD1-4 linked to OVOL2, COL8A2, ZEB1, and GRHL2, and variable severity from asymptomatic to glaucoma and corneal edema.

Oct 15, 2026

Posterior predictive distribution

The posterior predictive distribution is the probability distribution of new observations given observed data, formed in Bayesian inference by averaging the sampling distribution over the posterior parameter distribution.

Posterior probability

A posterior probability, also called the posterior distribution, is the probability assigned to a hypothesis after data are observed, produced by combining a prior with the likelihood through Bayes' theorem.

Posterior reversible encephalopathy syndrome

Posterior reversible encephalopathy syndrome (PRES, RPLS): clinicoradiological disorder of headache, seizures, encephalopathy, and visual loss with posterior vasogenic edema, triggered by hypertension, eclampsia, immunosuppression, and renal failure; not always reversible, with 10–19% mortality.

Posterior sagittal anorectoplasty

Posterior sagittal anorectoplasty (PSARP) is a pediatric operation, introduced in 1982, that repairs anorectal malformations by dissecting through the midline to place a new anus within the sphincter muscle complex.

Posterior sampling

Posterior sampling is the task of drawing representative samples from a Bayesian posterior distribution, usually by Markov chain Monte Carlo, to estimate moments and intervals.

Posterior superior intercostal plane block

The posterior superior intercostal plane block, or SPSIP block, is an ultrasound-guided fascial plane block, described in 2023 by Tulgar and colleagues, that provides analgesia for thoracic and breast surgery.

Posterior tibial artery

Posterior tibial artery (arteria tibialis posterior): terminal branch of the popliteal artery supplying the deep posterior calf and plantar foot, palpable behind the medial malleolus, used in pulse grading and ABI measurement.

Posterior tibial tendonitis

Posterior tibial tendonitis, also called PTTD or adult-acquired flatfoot, is inflammation or degeneration of the arch-supporting posterior tibial tendon, causing medial ankle pain and progressive flatfoot deformity, staged I to IV and treated first with orthoses and exercise.

Posterior urethral valve

Posterior urethral valve (PUV), a congenital obstructing membrane in the male posterior urethra attached to the verumontanum; the leading cause of pediatric lower urinary tract obstruction, affecting roughly 1 in 5,000 male births with substantial kidney failure risk.

Posterior vitreous detachment

Posterior vitreous detachment (PVD), separation of the vitreous gel from the retina, an age-related cause of flashes and floaters; risk of retinal tears rises with floaters, hemorrhage, and vitreous pigment, requiring dilated examination and 6-week follow-up.

Oct 15, 2026

Postes, Télégraphes et Téléphones

Postes, Télégraphes et Téléphones, or PTT, was the French state ministry operating postal, telegraph, and telephone services from 1878 until its dissolution on 1 January 1991.

Postgraduate diploma

Postgraduate diploma (PGDip, PgDip): a taught master's-level qualification, UK FHEQ Level 7, worth 120 credits versus 180 for a master's, same content without the dissertation; level 8 in New Zealand, level 9 in Ireland.

Postgraduate education

Postgraduate education (graduate education) is study after a first degree: master's, doctoral, and postgraduate diploma programs within tertiary education. Distinguished by graded degrees, the research doctorate, and three-cycle structures.

Oct 20, 2026

Postgraduate medicine

Postgraduate medicine: medical education after the primary medical degree, and the name of several journals, chiefly the British Postgraduate Medical Journal (Fellowship of Postgraduate Medicine, 1925, now Oxford University Press) and the American Postgraduate Medicine (Charles Mayo, roots 1916, Taylor & Francis).

PostgreSQL

PostgreSQL, also known as Postgres, is an open source object-relational database management system using SQL, descended from the 1986 POSTGRES project at the University of California, Berkeley.

Oct 26, 2026

PostgreSQL wire protocol

PostgreSQL wire protocol (Frontend/Backend Protocol): message-based client-server protocol over TCP/IP or Unix sockets, port 5432. Versions 2.0, 3.0 (7.4+), reserved 3.1, and 3.2 (PostgreSQL 18); simple and extended query sub-protocols.

Postherpetic neuralgia

Postherpetic polyneuropathy (ICD-11 1E91.5), also called postherpetic neuralgia, is chronic dermatomal neuropathic pain after shingles, caused by VZV reactivation damaging sensory nerves; affects 5–30% of zoster patients, mostly elderly.

Oct 22, 2026

Posthomerica

The Posthomerica, Greek τὰ μεθ' Ὅμηρον, is a fourteen-book Greek epic by Quintus of Smyrna covering the Trojan War from Hector's death to the Greeks' departure.

Posthuman

Posthuman (posthumanism, 后人类主义) is a late-20th-century family of theories questioning anthropocentrism and humanist subjectivity, distinct from transhumanism's human-enhancement program, with roots in feminism, poststructuralism, and STS, applied across animal studies, environmental humanities, and science fiction.

Posthumanism

Posthumanism: family of contemporary theoretical positions rejecting anthropocentrism and decentring the human; distinct from transhumanism, which enhances human limits; spans critical, philosophical, and cultural posthumanism, new materialism, and antihumanism.