Technology glossary

Dynamic Random-Access Memory(DRAM)

A form of volatile working memory that stores each bit in a tiny capacitor and must refresh the charge repeatedly. Phones, computers and servers use DRAM to hold data that processors need quickly while programs are running.

Dynamic Tissue Culture

A method for growing engineered tissue while applying controlled motion, pressure, flow or stretching. These physical cues can help cells organize and mature more like tissue inside a living body.

E911(E911)

Enhanced 911 (E911) is a U.S. emergency-calling capability that provides dispatchers with additional information, including the caller's location. Wireless E911 requirements helped accelerate deployment of location-capable mobile handsets and assisted-GPS technologies.

Early-Universe Black Hole

A black hole that formed during the universe's first hundreds of millions to roughly one billion years. Such objects, especially rapidly grown supermassive black holes powering distant quasars, help test theories of black-hole seeds, accretion, galaxy formation, and early cosmic evolution.

Earth System Model

A computer model that links the atmosphere, oceans, land, ice and biological or chemical cycles to simulate how the planet responds to forces such as greenhouse-gas emissions.

Ectodomain Shedding

A process in which an enzyme cuts the portion of a membrane protein that projects outside the cell, releasing that fragment into the surrounding fluid or bloodstream. The mechanism can rapidly change cell signaling without waiting for a new protein to be made.

Eddy Current

A circulating electrical current induced inside a conductor by a changing magnetic field. In motor and transformer cores, eddy currents waste energy as heat, so laminations or insulated particles are used to interrupt their paths.

Edge Computing

Processing data near the device or sensor that generates it instead of sending everything to a distant data center.

Effective Radiative Forcing(ERF)

A measure of how a change in greenhouse gases, clouds or other factors alters Earth’s energy balance after rapid atmospheric adjustments. Positive effective radiative forcing tends to warm the climate, while negative forcing tends to cool it.

El Niño-Southern Oscillation(ENSO)

A recurring tropical Pacific climate cycle that alternates among warmer El Niño, cooler La Niña and neutral conditions, reshaping weather worldwide.

Elastocaloric Effect

A reversible temperature change in certain materials when mechanical stress is applied or removed, allowing repeated loading cycles to pump heat.

Electric Propulsion

Spacecraft propulsion that uses electrical energy to accelerate propellant, commonly through electrostatic, electromagnetic, or electrothermal methods. It generally provides higher propellant efficiency but lower thrust than chemical rockets, making it suitable for long-duration missions and station keeping.

Electrocorticography(ECoG)

Electrocorticography is a method for recording electrical activity directly from the surface of the brain with electrodes placed beneath the skull. Because the sensors sit closer to neurons than scalp electroencephalography electrodes, ECoG can capture faster and more spatially detailed signals, but it requires neurosurgery. In brain-computer interfaces, algorithms can use these recordings to infer attempted speech or movement.

Electrode Fouling

The accumulation of minerals, organic matter or reaction products on an electrode surface, which can block active sites, increase resistance and reduce electrochemical performance.

Electroencephalography(EEG)

A method that records electrical activity produced by the brain using electrodes placed on or near the scalp.

Electroforming

A process that deposits metal onto a removable form using an electric current until the deposited layer becomes a self-supporting component.

Electron-Beam Irradiation(EBI)

A process that exposes material or air to high-energy electrons to damage microbes or alter materials.

Electron-hole recombination

Electron-hole recombination occurs when an excited electron returns to an unoccupied electronic state called a hole. The process releases energy as light, heat or vibrations and removes charge carriers that a solar cell might otherwise collect as electric current. Recombination can be intrinsic to a material or accelerated by defects, surfaces and interfaces.

Electron-Transport Layer(ETL)

A layer in an electronic or photovoltaic device that selectively carries electrons from an active material to an electrode while limiting the movement of positive charge carriers. Its energy levels, conductivity, and interface quality strongly affect device efficiency and stability.

Electronic Door Latch

A door-locking mechanism that uses an electrical signal from a button, sensor or control module to release the latch. Vehicles still need a mechanical backup because crash damage or loss of low-voltage power can stop the electronic command.

Electronic nose(E-nose)

A sensing system that uses an array of chemical or gas sensors plus pattern-recognition software to classify odors or volatile compounds. It does not smell as a person does or necessarily identify every molecule in a sample.

Emergency Diversion

A change from an aircraft's planned destination or route to reach a suitable airport because continuing the original flight would create unacceptable risk.

Emissivity Control

The adjustment of a surface's ability to emit thermal radiation. Coatings, structures, phase-change materials, or electronic controls can vary emissivity to manage heating and cooling in buildings, spacecraft, sensors, and energy systems.

Enabled Emissions

Additional greenhouse gas emissions that become possible when a technology lowers costs, raises productivity or expands a carbon-intensive activity. The term includes indirect effects, such as AI making additional fossil-fuel extraction economically viable.

Enantiomer

An enantiomer is one of a pair of chiral molecules that are mirror images but cannot be superimposed. The pair has the same atomic connections, yet each form can behave differently when it encounters another chiral molecule or biological target.

Energy Turnover Point

In atmospheric predictability research, a proposed time by which incoming energy has propagated through the atmosphere widely enough to erase information about an exactly known initial state. It is a theoretical concept and is not an operational forecast horizon.

Engine-Out Capability

The ability of a multi-engine vehicle to continue a mission after one engine stops producing useful thrust. Guidance software may adjust the remaining engines, extend their burn or revise the flight plan. The capability depends on when the failure occurs, available propellant, control authority and performance margins.

Engineered Living Material

A material that uses living cells as active components to sense, respond, grow or repair.

Engineering Copilot

An AI-based assistant that supports engineering tasks such as drafting designs, writing code, analyzing requirements, running calculations, searching documentation, or checking work. Its outputs require validation because errors, missing context, or unsuitable assumptions can affect safety and performance.

Ensemble Weather Forecast

A set of weather predictions produced with varied initial conditions or model configurations to estimate the range and probability of possible atmospheric outcomes.