All articles starting with S
44,216 articles
Self-phase modulation
Self-phase modulation (SPM) is a nonlinear optical effect in which an intense light pulse induces a time-dependent phase shift on itself through the Kerr effect, producing chirp and spectral broadening.
Self-piercing rivet
A self-piercing rivet (SPR) is a semi-tubular fastener driven by a punch through upper sheets, flaring in a die to form a mechanical interlock without a pre-drilled hole or heat.
Self-pillared pentasil zeolites
Self-pillared pentasil zeolites are hierarchical zeolites made of unit-cell-thick MFI nanosheets intergrown at right angles with MEL at branch points, giving a house-of-cards morphology whose mesopores speed diffusion.
Self-play
Self-play is a reinforcement learning method in which an agent improves by playing against copies of itself, the paradigm behind AlphaGo Zero, AlphaZero, and MuZero.
Self-play and self-rewarding alignment
Self-play and self-rewarding alignment are post-training methods where a language model generates candidate responses, judges them itself, and trains its next iteration on the resulting preferences.
Self-pollination
Self-pollination (autogamy, geitonogamy, cleistogamy) is pollen transfer within a flower or between flowers of the same plant, enabling self-fertilization; the most common evolutionary transition in flowering plants, favored by reproductive assurance and transmission advantage but limited by inbreeding depression.
Self-portrait
A self-portrait, or autoportrait, is a likeness of an artist made by the artist, in media from oil painting to photography, attested from the late Middle Ages.
Self-Portrait Dedicated to Leon Trotsky
Self-Portrait Dedicated to Leon Trotsky (Autorretrato dedicado a León Trotsky), also called Between the Curtains, is Frida Kahlo's 1937 oil self-portrait with a dated dedication to Trotsky, held by the National Museum of Women in the Arts since Clare Boothe Luce's 1988 gift.
Self-Portrait in a Convex Mirror
"Self-Portrait in a Convex Mirror" is a long 1975 poem by John Ashbery, an ekphrastic meditation on Parmigianino's 1524 painting in which the artist paints his face distorted by a convex mirror.
Self-Portrait on the Borderline Between Mexico and the United States
Self-Portrait on the Borderline Between Mexico and the United States is a 1932 oil-on-metal painting by Frida Kahlo, made during her years in the United States with Diego Rivera.
Self-Portrait with Thorn Necklace and Hummingbird
Self-Portrait with Thorn Necklace and Hummingbird (Autorretrato con collar de espinas y colibrí) is a 1940 self-portrait by Frida Kahlo, held at the Harry Ransom Center in Texas.
Self-Portrait with Two Circles
Self-Portrait with Two Circles is an oil-on-canvas self-portrait by Rembrandt van Rijn, painted around 1665 in his last years and now in Kenwood House, London.
Self-potential
Self-potential (SP), also called spontaneous potential, is a passive geophysical survey method measuring natural voltage differences at the Earth's surface, first observed by Robert W. Fox in 1830.
Self-praise of Shulgi (Shulgi D)
Self-praise of Shulgi (Shulgi D) is a Sumerian royal hymn in which Shulgi, second king of the Third Dynasty of Ur, praises himself as an ideal ruler.
Self-proclaimed monarchy
Self-proclaimed monarchy: a monarchy claimed without dynastic ties, from Zog I of Albania to micronational crowns like Hutt River, Sealand, and Seborga, unrecognized by established states.
Self-propagating high-temperature synthesis
Self-propagating high-temperature synthesis (SHS) is a combustion-based method for making ceramics, intermetallics, and other refractory compounds, discovered in the Soviet Union in 1967, in which a reaction front moves through compacted powder without a furnace.
Self-propelled anti-aircraft weapon
A self-propelled anti-aircraft weapon, often called a SPAAG, is a mobile vehicle with anti-aircraft cannons or missiles, protecting armored forces from low-flying aircraft since World War II.
Self-propelled artillery
Self-propelled artillery, also called a self-propelled gun, is a howitzer mounted on a tracked or wheeled vehicle, able to displace quickly after firing to avoid counter-battery fire.
Self-propelled colloids
Self-propelled colloids are micrometer-sized particles that convert free energy from their surroundings into directed motion, acting as synthetic analogs of swimming algae and bacteria and studied within active matter since 2004.
Self-propelled droplets
Self-propelled droplets are droplets of one fluid in another that swim autonomously by Marangoni flows driven by interfacial tension gradients, a class of active matter.
Self-publishing
Self-publishing: authors fund and manage their own book production, editing, distribution, and marketing, keeping rights and 35–70% royalties, chiefly via Amazon KDP (launched 2007); 3.5 million US self-published titles in 2025 versus 642,242 traditional.
Self-pulsation
Self-pulsation (self-pulsing) is the spontaneous generation of laser light pulses without an external modulator, under a steady pump; it was first reported in masers in 1958.
Self-RAG
Self-RAG is a fine-tuning method for large language models, introduced in 2023, in which the model itself decides when to retrieve passages and critiques them using reflection tokens.
Self-realization
Self-realization, equated with self-actualization in psychology, is the development and expression of one's true potentials; defined philosophically by Routledge, tied to eudaimonic well-being by Ryan and Deci, and critiqued for Western individualist assumptions.
Self-Realization Fellowship Lake Shrine
Self-Realization Fellowship Lake Shrine: 10-acre Pacific Palisades meditation sanctuary on Sunset Boulevard, founded by Paramahansa Yogananda, dedicated 1950, spring-fed Lake Santa Ynez, Gandhi ashes memorial, survived the 2025 Palisades Fire.
Self-reduction (chemistry)
Self-reduction is a chemical synthesis method in which the substrate or support itself reduces a metal precursor to nanoparticles, single atoms, or films, with no added reducing agent.
Self-reference
Self-reference, also called self-reflexivity, is the relation an object bears when it refers to itself, the source of the liar paradox and Gödel's incompleteness theorems.
Self-referential humor
Self-referential humor, or meta humor, is comedy whose material points at itself, its own form, length, or telling. Seen in jokes, meta-theatre like Hamlet's play-within-a-play, and the George Burns sitcom.
Self-refine
Self-Refine is a prompting-time method for large language models where a single model generates, critiques, and revises its own outputs, improving performance by about 20% on average without any training.
Self-refine and iterative prompting
Self-refine is an inference-time method, introduced in March 2023, in which a language model acts as generator, critic, and refiner, improving its output without additional training.