All articles starting with R
22,461 articles
Reflection seismology
Reflection seismology, also called seismic reflection, is a geophysical method that maps subsurface rock layers from reflected seismic waves and is the petroleum industry's principal imaging tool.
Reflection spectroscopy
Reflection spectroscopy measures the light returned by a material's surface to determine its composition, structure, and optical constants across the ultraviolet, visible, near-infrared, and mid-infrared ranges.
Reflection symmetry
Reflection symmetry, also called line symmetry or reflective symmetry, is the invariance of an object or pattern under reflection across a fixed line or plane of symmetry.
Reflectionless metasurfaces
Reflectionless metasurfaces are electrically thin engineered surfaces that transform electromagnetic waves, such as by refraction or focusing, while producing no specular reflection of their own.
Reflections (From Ashes to New album)
Reflections is the fifth studio album by Pennsylvania band From Ashes to New, released April 17, 2026 via Better Noise Music, made after the band scrapped 16 demos, with "Drag Me" giving them their first Billboard Mainstream Rock No. 1.
Reflections at the Front Entrance
Reflections at the Front Entrance (Размышления у парадного подъезда) is an 1858 poem by Nikolai Nekrasov about peasants turned away from a St. Petersburg grandee's door.
Reflections in a Golden Eye (film)
Reflections in a Golden Eye (1967) is John Huston's film of Carson McCullers's 1941 novel, starring Elizabeth Taylor, Marlon Brando, Brian Keith, and Julie Harris as officers and spouses on a Georgia army post; shot in a distinctive sepia-golden Technicolor, it flopped on release and was later reappraised as Southern Gothic.
Reflections on the Motive Power of Fire
Reflections on the Motive Power of Fire (Réflexions sur la puissance motrice du feu) is an 1824 scientific treatise by French engineer Sadi Carnot, regarded as the founding document of thermodynamics.
Reflections on the Revolution in France
Reflections on the Revolution in France is Edmund Burke's November 1790 pamphlet, a reply to Richard Price, defending inherited institutions against revolutionary abstraction, answered by Paine's Rights of Man and foundational for modern conservatism.
Reflective equilibrium
Reflective equilibrium is a method in moral and political philosophy, introduced by John Rawls in 1971, that adjusts moral principles and judgments against each other until they cohere.
Reflective learning
Reflective learning is a pedagogical and psychological approach in which learners deliberately review and analyze their experiences to improve future practice, underpinning training in nursing and medicine.
Reflective listening
Reflective listening is a communication technique in which the listener restates or paraphrases a speaker's thoughts and feelings as a statement, a core skill of person-centered therapy and motivational interviewing.
Reflective practice
Reflective practice, from John Dewey and Donald Schön, is the deliberate examination of one's professional actions to improve them, distinguishing reflection-in-action from reflection-on-action; it is embedded in nursing and teacher education despite contested evidence.
Reflective semiconductor optical amplifier transmitter
A reflective semiconductor optical amplifier (RSOA) transmitter amplifies an incoming optical carrier and modulates data onto it, serving as a colorless, wavelength-agnostic transmitter in WDM-PON fiber networks.
Reflective writing
Reflective writing is the practice of describing and analyzing one's own experiences in writing to promote learning and emotional processing, used in education, professional training, and therapy.
Reflectometry
Reflectometry is a measurement technique that directs light, X-rays, or neutrons at a surface and analyzes reflected intensity to determine film thickness, refractive index, and interface quality.
Reflector sight
A reflector sight, also called a reflex sight, is an optical sight that projects an illuminated aiming point onto glass, patented by Howard Grubb in 1901.
Reflectron
A reflectron, also called an ion mirror, is a component of a time-of-flight mass spectrometer that improves mass resolution by compensating for ions' energy spread.
Reflektor
Reflektor is the fourth studio album by the Canadian rock band Arcade Fire, a double album co-produced by James Murphy of LCD Soundsystem, released in October 2013.
Reflex
A reflex is an automatic, involuntary response to a stimulus mediated by a fixed neural pathway, the reflex arc, ranging from the knee jerk to protective withdrawal.
Reflex Aerospace
Reflex Aerospace is a German satellite manufacturer founded in Munich in 2021 that builds payload-specific satellite platforms for commercial and defense use, launching its first satellite, SIGI, in January 2025.
Reflex arc
A reflex arc, or reflex circuit, is the neural pathway that produces an automatic, involuntary response to a stimulus, integrating it in the spinal cord or brainstem without conscious involvement.
Reflex incontinence
Reflex incontinence (ICD-11 MF50.24): urinary incontinence accompanying detrusor hyperreflexia, leaking without warning urge after nerve damage from stroke, spinal cord injury, or multiple sclerosis; managed with catheterization and anticholinergics.
Reflex syncope
Reflex syncope, or neurally mediated syncope, is fainting from an inappropriate cardiovascular reflex causing vasodilatation and/or bradycardia; forms include vasovagal, situational, and carotid sinus syncope, treated first with counterpressure maneuvers and, in selected asystolic cases, pacing.
Reflex testing (laboratory medicine)
Reflex testing is a laboratory medicine practice in which a pre-determined result, such as a positive screen, automatically triggers confirmatory tests on the same specimen without a new physician order.
Reflexion
Reflexion is a 2023 method for improving language-model agents, introduced by Noah Shinn and colleagues: agents write verbal self-assessments of failed attempts into memory, so later retries improve without any weight updates.
Reflexive operator algebra
A reflexive operator algebra is an algebra of bounded operators equal to the algebra of all operators sharing its invariant subspaces, a notion tied to the invariant subspace problem.
Reflexive pronoun
Reflexive pronouns (myself, himself, themselves) refer back to a clause's subject; English forms end in -self/-selves. Covers intensive uses, Binding Principle A locality, long-distance reflexives like Chinese ziji, cross-linguistic typology, and the grammaticalization history of English self-forms.
Reflexive relation
A reflexive relation, also called the reflexive property, is a binary relation on a set in which every element is related to itself, as with the identity relation.
Reflexive space
A reflexive space is a Banach space that coincides with its second dual under the canonical embedding, so that its closed unit ball is weakly compact.