All articles starting with O
9,097 articles
Orthokeratology
Orthokeratology, or ortho-K, is a vision-correction method in which rigid gas-permeable contact lenses are worn overnight to temporarily flatten the cornea, correcting myopia without daytime glasses.
Orthomodular lattice
An orthomodular lattice is a bounded lattice with an orthocomplement satisfying the orthomodular law, a weakening of distributivity that serves as the standard algebraic semantics for quantum logic.
Orthomolecular Therapy
Orthomolecular therapy, or megavitamin therapy, uses very large doses of vitamins and body-normal substances, chiefly for mental disorders. Coined by Linus Pauling in 1968; contested by mainstream psychiatry since the 1973 APA task force report.
Orthomyxoviridae
Orthomyxoviridae, the influenza virus family, enveloped negative-sense segmented RNA viruses in order Articulavirales; genera Alphainfluenzavirus through Deltainfluenzavirus, Isavirus, Quaranjavirus, Thogotovirus; reassortment drives pandemics.
Orthonairovirus haemorrhagiae
Orthonairovirus haemorrhagiae, the Crimean-Congo hemorrhagic fever virus (CCHFV), is a tick-borne RNA virus endemic across Africa, the Middle East, Asia, and Europe that causes severe hemorrhagic fever with fatality rates up to 30%.
Orthonormal basis
An orthonormal basis, also called a complete orthonormal system, is a basis of an inner product space with unit-length, mutually orthogonal vectors, and it extends to Hilbert spaces.
Orthonormality
Orthonormality is the property of a set of vectors, such as an orthonormal basis, whose members are unit vectors and mutually orthogonal, with inner products given by the Kronecker delta.
Orthopaedic Research Society
Orthopaedic Research Society (ORS), founded 1954 in Chicago, non-profit 501(c)(3) musculoskeletal research society; publisher of the Journal of Orthopaedic Research and JOR Spine, founding member of ICORS, OREF, and IFMRS.
Orthopaedic surgery
Orthopaedic surgery, the surgical specialty of the musculoskeletal system, supports a large journal ecosystem: 478 journals, impact factor trends, double-blind peer review, publication costs, and predatory-journal risks.
Orthopedic and rehabilitation management of Duchenne muscular dystrophy
Orthopedic and rehabilitation management of Duchenne muscular dystrophy is the set of non-drug interventions, including stretching, orthoses, physiotherapy, and spinal surgery, that preserve movement and comfort as weakness progresses.
Orthopedic cast
An orthopedic cast, also called a surgical cast, is a rigid plaster of Paris or fiberglass shell holding broken bones in position while they heal.
Orthopedic Equipment
Orthopedic equipment: nonexpendable surgical and therapy devices for bones and joints, per MeSH D009983, distinct from orthotic devices; includes instruments, fixation hardware, arthrometers, navigation and robotic systems.
Orthopedic Manipulation
Orthopedic manipulation is the controlled manual movement of the spine, extremities, and other musculoskeletal structures to increase motion, diagnose disease, reduce dislocations, or improve fracture alignment.
Orthopedic nursing
Orthopedic (orthopaedic) nursing is the nursing specialty caring for musculoskeletal patients. Key facts: MeSH specialty since 1992, NAON professional body, Orthopaedic Nursing journal since 1982, advanced practice roles, and evidence-based practice research.
Orthopedic Surgeons
Orthopedic surgeons (orthopedists) are physicians treating skeletal, joint, and musculoskeletal disorders by medical, surgical, and physical means. Named from Andry's 1741 term; about 14 years of training; subspecialties from spine to sports medicine.
Orthopedic surgery
Orthopedic surgery treats musculoskeletal disorders of bones, joints, and soft tissues. Term coined in the 1700s; shaped by anesthesia, antisepsis, and X-rays; now spans joint replacement, trauma, spine, and robotics-assisted procedures.
Orthopedics
Orthopedics is a peer-reviewed journal published by SLACK Incorporated since 1978 (ISSN 0147-7447), covering clinical orthopedic surgery; MEDLINE-indexed, 2025 impact factor 1.3, Scopus Q2.
Orthopnea
Orthopnea is shortness of breath when lying flat, relieved by sitting or standing, mainly caused by heart failure, COPD, obesity, and pulmonary venous hypertension; distinct from PND.
Orthopneumovirus bovis
Orthopneumovirus bovis is a virus species in the family Pneumoviridae whose member virus, bovine respiratory syncytial virus, is a major cause of respiratory disease in calves.
Orthopneumovirus hominis
Orthopneumovirus hominis, formerly Human orthopneumovirus and human respiratory syncytial virus (RSV, HRSV), is the Pneumoviridae virus species causing infant bronchiolitis, renamed by ICTV in 2022.
Orthopodomyia
Orthopodomyia (Theobald, 1904), sole genus of tribe Orthopodomyiini, is a genus of 36 ornate tree hole mosquito species of the Neotropics and Orient, harmless to humans, diagnosed by elongated foreleg tarsomere 1.
Orthopoxvirus vaccinia
Orthopoxvirus vaccinia (vaccinia virus, VACV) is the prototype orthopoxvirus species, the smallpox vaccine virus of obscure origin with no known natural host, a broad host range, and a ~195 kb cytoplasm-replicating dsDNA genome, now used in MVA-based vaccines and oncolytic vectors.
Orthopoxvirus variola
Orthopoxvirus variola (variola virus, VARV) is the human-specific orthopoxvirus species causing smallpox; eradicated in 1980, live stocks remain only at CDC Atlanta and VECTOR, Koltsovo, under WHO oversight.
Orthopraxy
Orthopraxy, also called orthopraxis, is proper action in religion, contrasted with orthodoxy, proper belief; Judaism, Hinduism, and Confucianism are commonly described as practice-centered, and the term entered Christian theology in the 1960s.
Orthoptera
Orthoptera, the insect order of grasshoppers, locusts, crickets, and katydids, with suborders Ensifera and Caelifera, about 29,400 described species, stridulatory sound production, and jumping hind legs.
Orthoptics
Orthoptics is an allied health discipline concerned with the assessment, diagnosis, and non-surgical treatment of binocular vision, eye movement, and eye alignment disorders, including amblyopia and strabismus.
Orthorectification
Orthorectification is a remote sensing image processing method that removes geometric distortions from aerial or satellite imagery caused by sensor tilt, viewing geometry, and terrain relief, producing a map-accurate orthoimage.
Orthorexia nervosa
Orthorexia nervosa (ON), coined by Steven Bratman in 1997, is a proposed disorder of obsessive healthy eating, not in DSM-5 or ICD-11, with prevalence estimates from 1% to 90% and no validated clinical diagnostic tool.
Orthorubulavirus parotitidis
Orthorubulavirus parotitidis, the ICTV species for mumps virus (MuV), renamed from Mumps orthorubulavirus in 2022; a Paramyxoviridae orthorubulavirus causing human mumps, parotitis, orchitis, and meningitis, controlled by MMR vaccine.
OrthoSensor
OrthoSensor was a medical-device company founded in 2007 in Dania Beach, Florida, best known for the Verasense knee sensor, acquired by Stryker in December 2020.