All articles starting with S

Single-particle cryo-electron microscopy

Single-particle cryo-electron microscopy (single-particle cryo-EM) determines the 3D structures of biological macromolecules by computationally averaging images of individual molecules frozen in vitreous ice, complementing X-ray crystallography and NMR spectroscopy.

Single-particle imaging

Single-particle imaging is an X-ray method in which femtosecond pulses from an X-ray free-electron laser record diffraction patterns from individual particles, which are merged into 3D structures without crystallization or radiation damage.

Single-particle inductively coupled plasma mass spectrometry

Single-particle inductively coupled plasma mass spectrometry (spICP-MS) is an analytical technique that counts and sizes metal-containing nanoparticles, recording each particle as a transient ion pulse.

Single-payer healthcare

Single-payer healthcare: one public entity finances and pays for universal health coverage, as in Canada's Medicare and Taiwan's National Health Insurance; defined by CBO's four features, contrasted with multipayer systems.

Single-phase electric power

Single-phase electric power, abbreviated 1φ, is alternating current distribution in which all supply voltages vary in unison, serving homes and small buildings while three-phase systems serve industrial loads.

Single-phase induction motor

A single-phase induction motor is an AC motor that runs from a single-phase supply and needs auxiliary means, such as a capacitor or shading coil, to start.

Single-photon avalanche diode

A single-photon avalanche diode (SPAD), also called a Geiger-mode avalanche photodiode, is a semiconductor photodetector that detects single photons and is used in LiDAR and PET scans.

Single-photon detector

A single-photon detector (SPD) is a device that converts individual photons into measurable electrical signals, underpinning quantum key distribution and computing, with types including SNSPDs, transition-edge sensors, and avalanche photodiodes.

Single-photon emission computed tomography

Single-photon emission computed tomography, known as SPECT or radionuclide computed tomography, is a nuclear medicine technique that reconstructs 3D images of radioactive tracer distribution using rotating gamma cameras, often to image the brain, heart, and skeleton.

Single-photon emitters in WSe2

Single-photon emitters in WSe2 are quantum emitters in monolayer tungsten diselenide, first reported in 2015, that emit one photon at a time from defect- or strain-localized excitons.

Single-photon nonlinearity

Single-photon nonlinearity is an optical effect in which one photon alters the behavior of another, the defining requirement of quantum nonlinear optics and enabling photon blockade and quantum logic gates.

Single-photon source

A single-photon source is a light source that emits one photon per excitation event, showing antibunching rather than laser-like statistics, and underlies quantum cryptography and computing.

Single-photon transistor

A single-photon transistor is a device in which a single gate photon controls the propagation of many signal photons, the optical analog of an electronic transistor at the quantum limit.

Single-player video game

Single-player video game: a game designed for one player, contrasted with multiplayer play with other real-life people. Spans genres from shooters to RPGs; early examples include OXO (1952) and Spacewar! (1962); saw renewed industry attention in 2026.

Single-point urban interchange

A single-point urban interchange is a highway interchange where all freeway ramps meet the cross street at one large signalized intersection, developed in 1970 to improve traffic capacity.

Single-pot solid-phase-enhanced sample preparation

Single-pot solid-phase-enhanced sample preparation (SP3) is a paramagnetic bead–based method for preparing protein samples before mass-spectrometry proteomics, introduced by Christopher S. Hughes and colleagues in 2018.

Single-precision floating-point format

Single-precision floating-point format, also known as binary32 or Float32, is a 32-bit IEEE 754 format for approximate real numbers, the default in graphics and machine learning.

Single-qubit gates

A single-qubit gate is a unitary 2×2 matrix acting on one qubit, including the Pauli, Hadamard, phase, and rotation gates, each a Bloch-sphere rotation; the gates form the group U(2).

Single-responsibility principle

The single-responsibility principle (SRP) is a software design principle, introduced by Robert C. Martin in the late 1990s, stating each class should have only one reason to change.

Single-screw extruder

A single-screw extruder is a continuous machine with one rotating screw inside a heated barrel that conveys, melts, and pressurizes material, most often thermoplastic polymer, through a shaping die.

Single-sex boarding schools

A single-sex boarding school is a residential school that admits pupils of one sex only, distinct from co-educational schools that merely separate classes or year groups.

Single-sex education

Single-sex education teaches boys and girls separately in classrooms or schools. Key evidence: the 2014 meta-analysis of 184 studies found trivial controlled effects, while Trinidad and Tobago's 2010 conversions of 20 schools showed causal gains in exam scores, completion, and behavior.