All articles starting with O
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Orthosias
Orthosias (Greek Ὀρθωσία, Latin Ortosia) was a Phoenician coastal town in northern Lebanon near the river Eleutherus, between Arwad and Tripoli, whose 2009 excavated remains were reburied under a refugee camp.
Orthosiphon
Orthosiphon (syn. Clerodendranthus) is a genus of 45 accepted Lamiaceae species native from Colombia and Africa to northeast Australia; its best-known species, O. aristatus or O. stamineus (cat's whiskers, misai kucing), is a Southeast Asian medicinal plant used as a diuretic and studied for antidiabetic effects.
Orthosphinctes
Orthosphinctes (Schindewolf, 1925; type species Ammonites tiziani) is a Late Jurassic perisphinctid ammonite genus, intermediate between Perisphinctes and Ataxioceras, ranging from the Upper Oxfordian into the lower Kimmeridgian across Europe.
Orthostatic hypertension
Orthostatic hypertension: a sustained systolic blood pressure rise of at least 20 mmHg on standing with standing SBP at least 140 mmHg, per the American Autonomic Society and Japanese Society of Hypertension consensus definition; linked to sympathetic overactivity and hypertension.
Orthostatic hypotension
Orthostatic hypotension (postural hypotension): a fall of ≥20 mm Hg systolic or ≥10 mm Hg diastolic within 3 minutes of standing. Neurogenic (autonomic failure, synucleinopathies) versus non-neurogenic (drugs, hypovolemia) forms; treated with fluids, salt, compression, midodrine, droxidopa.
Orthostatic intolerance
Orthostatic intolerance: symptoms of cerebral hypoperfusion or sympathetic activation while standing, relieved by lying down. Covers orthostatic hypotension, vasovagal syncope, and POTS (heart rate rise ≥30 bpm without blood pressure fall).
Orthostatic proteinuria
Orthostatic (postural) proteinuria: excess urinary protein only when upright, normal when supine; benign condition affecting 2-5% of adolescents, diagnosed by first-morning urine testing, requiring no treatment.
Orthosulfamuron
Orthosulfamuron (CAS 213464-77-8, trade name Kelion) is a sulfamoylurea ALS-inhibiting herbicide used pre- and post-emergence against grass and broadleaf weeds in rice, registered in 13 countries.
Orthotic Devices
Orthotic devices, or orthoses, are braces, slings, and supports worn outside the body to align or stabilize weak body parts, unlike prostheses, which replace missing parts.
Orthotics
Orthotics, also known as orthopedic or orthopedic braces, is the branch of healthcare concerned with orthoses, externally applied devices that support joints, correct alignment, and relieve pain.
Orthotopic implantation
Orthotopic implantation is a cancer modeling technique in which tumor cells or tissue are transplanted into the matching organ, so the tumor grows in its natural microenvironment.
Orthotopic xenograft model
The orthotopic xenograft model transplants human tumor cells or tissue into the organ of origin in an immunodeficient mouse, so tumors grow in their native microenvironment.
Orthotospovirus
Orthotospovirus is the sole genus of plant-virus family Tospoviridae (order Elliovirales), with 36 species including tomato spotted wilt virus; tripartite ambisense RNA genome, thrips-transmitted, 80–120 nm enveloped virions.
Orthotrichales
Orthotrichales is an order of mosses (Bryophyta, Bryopsida) centered on the Orthotrichaceae, about 900 epiphytic species; includes yoke-, bristle-mosses, and pincushions; rbcL data suggest the order is polyphyletic.
Orthotropic deck
An orthotropic deck, or orthotropic steel deck, is a lightweight steel bridge deck of rib-stiffened plate and floorbeams acting as one structure, developed in Germany in the 1930s for long-span bridges.
Orthotropic material
An orthotropic material is a material with elastic properties differing along three mutually perpendicular axes, described by nine independent elastic constants; wood, composite laminates, and cortical bone are examples.
Orthrus
Orthrus (Ὄρθρος, also Orthus or Orthos) is the two-headed dog of Greek myth, son of Typhon and Echidna, brother of Cerberus, father of the Sphinx and Nemean Lion, guardian of Geryon's cattle, killed by Heracles.
Ortivity
Ortivity is a German buy-and-build platform for outpatient orthopedic care. Founded in 2022, it scaled to over 100 locations and received a €200 million growth investment in 2025.
Ortiz (wrestler)
Ortiz (Miguel Molina, born 1991) is an American professional wrestler of Puerto Rican descent from Harlem, NY, signed to AEW; former LAX and Proud-N-Powerful tag team partner of Mike Santana.
Ortler / Ortlés
Ortler (Italian: Ortles), 3,905 m, is the highest mountain of South Tyrol and of the Eastern Alps outside the Bernina Range. First climbed 27 September 1804 by Josef Pichler; its north face is the Eastern Alps' largest ice face.
Orto Botanico dell'Università degli Studi di Cagliari
The Orto Botanico dell'Università degli Studi di Cagliari, formally the Hortus Botanicus Karalitanus, is a botanical garden founded by the University of Cagliari in Cagliari, Sardinia, in 1866.
Orto dei Semplici Elbano
Orto dei Semplici Elbano: botanical garden of about one hectare at the Eremo di Santa Caterina, Rio nell'Elba, Elba; founded 1992 by Corsi, Garbari and Berger, opened 1997; conserves Tuscan Archipelago medicinal and endemic plants.
Orto e Museo Botanico di Pisa
Orto e Museo Botanico di Pisa (Botanic Garden and Museum of the University of Pisa), founded 1543-44 by Luca Ghini under Cosimo I de' Medici; the world's oldest university botanic garden, moved twice, now about two hectares with 3,000 plants and a 350,000-specimen herbarium.
Ortogh
An ortogh (ortoq, ortaq) was a merchant in the Mongol Empire who traded or lent money with capital supplied by a prince or the imperial court.
Ortolan bunting
Ortolan bunting (Emberiza hortulana), a 16.5 cm migratory bunting breeding from Spain to Mongolia and wintering in sub-Saharan Africa. Two flyways split at a Belarus-to-Serbia divide; European population fell about 92%, the steepest of any European bird.
Orton Chirwa
Orton Chirwa was a Malawian lawyer and politician who founded the Malawi Congress Party, served as Malawi's first Minister of Justice, and died in prison in 1992.
Ortona
Ortona: Adriatic coastal town in Chieti province, Abruzzo, Italy, on a ~70 m promontory southeast of Pescara; ancient principal port of the Frentani, Byzantine stronghold, home of St. Thomas relics, and heavily destroyed 1943 Canadian battle site.
Ortrun Enderlein
Ortrun Enderlein (Ortrun Enderlein-Zöphel, born 1943), East German luger, first Olympic women's singles luge champion at Innsbruck 1964 and world champion 1965 and 1967; disqualified while leading at Grenoble 1968 for heated runners.
Ortwin Hess
Ortwin Hess is a theoretical physicist working in quantum nanophotonics and metamaterials at Trinity College Dublin, known for the 2007 trapped rainbow principle and the Royal Society's Rumford Medal.
Ortygia Colles
Ortygia Colles, a 255.62-km-wide group of small hills (colles) on Mars at 53.90N, 350.70E, IAU-approved in 2003 and named for the classical albedo feature Ortygia, the island of Delos.