electro-, electr-, electri-

An intracardiac electrogram which records electrical potentials within the coronary sinus: A coronary sinus electrogram is used for the indirect monitoring of the left ventricular hollow parts or cavities in an organ or in each of the two main chambers of the heart, left and right.

1. The science concerned with electromagnetic phenomena in ionized media encountered in interstellar space, in stars, and above the atmosphere.
2. The physics of the interactions of moving, charged particles and magnetic fields in planetary atmospheres, stars, and interstellar and intergalactic space.

1. A law which describes the electric force between charged objects which states that:

• Like charges repel each other and unlike charges attract each other.
• The attraction or repulsion acts along the line between the two charges.
• The size of the force varies inversely as the square of the distance between the two charges.
• The size of the force is proportional to the value of each charge.

2. In physics, a law stating that the electrostatic force between two charged bodies is proportional to the product of the amount of charge on the bodies divided by the square of the distance between them.

If the bodies are oppositely charged, one positive and one negative, they are attracted toward one another; if the bodies are similarly charged, both positive or both negative, the force between them is repulsive.

Coulomb's law applies only when the charged bodies are much smaller than the distance separating them and therefore can be treated approximately as point charges.

A laboratory technique in which an electric current is used to accelerate the migration of an antibody and an antigen through a buffered diffusion medium.

Antigens in a gel medium in which the pH is controlled are strongly negatively charged and will migrate rapidly across the electric field toward the anode.

The antibody in such a medium is less negatively charged and will migrate in an opposite or "counter" direction toward the cathode.

If the antigen and antibody are specific for each other, they combine and form a distinct line of precipitation.

This technique is becoming increasingly useful for detecting antigens or antibodies specific for given infectious diseases, diagnosing clinical bacterial infections, and choosing medications to treat the infections.

A technique for electrophoretic separation (science of objects moving in a fluid when an electric charge is applied) of mixed proteins in which two successive currents are passed through the support medium in directions at right angles to each other.

It is used in two-dimensional immunoelectrophoresis, separation and identification of proteins based on differences in electrical charge and reactivity with antibodies.

An electron microscopic technique that involves freezing the biological sample in order to view the sample with the least possible distortion and the fewest possible artifacts. Abbreviated as cryo-EM.

In cryoelectron microscopy, the freezing of the sample is done in ethane slush to produce vitreous, or non-crystalline, ice. The frozen sample grid is then kept at liquid nitrogen temperature in the electron microscope and digital micrographs are collected with a camera.

The advantages of cryo-EM over traditional EM techniques include the preservation of the sample in a near-native hydrated state without the distortions from stains or fixatives needed for traditional EM. With image processing and averaging of multiple images, cyroelectron microscopy provides high resolution information (below 10 angstroms).

An angstrom is a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation.

A field of engineering that studies the design and functioning of electronics systems, circuits, and devices at temperatures approaching absolute zero (0 Kelvin or -270 degrees Celsius); especially, as applied to the phenomenon of superconductivity.

An electrode with greater resistance than the part of the human body that is enclosed in the circuit.

1. A dark box constructed for viewing transparent pictures, with or without a lens.
2. An instrument for the transillumination of a body cavity or the passage of strong light through a body structure, to permit inspection by an observer on the opposite side.

A transillumination or the passage of light through body tissues for the purpose of medical examination which involves the object or part under examination being interposed between the observer and the light source.

1. A reference to material; such as, glass or porcelain with negligible electrical or thermal conductivity.
2. Pertaining to a substance or medium that can sustain a static electric field within it.
3. Relating to something that is a poor conductor of electricity, but an efficient supporter of electrostatic fields: Dielectric conditions can support an electrostatic field while dissipating minimal energy in the form of heat; frequently used in capacitors.
4. A type of insulator which becomes polarized when it comes in contact with an electrical field: The dielectric material can easily support an electrostatic field even though it is not a conductor of electricity.

Such dielectric materials are used in many places; such as, in capacitors and radios, as well as transmission lines for radio frequency and it can be used to store energy too, if it is configured properly.

Most of these dielectric materials are solid in nature, but some fluids and gasses also exhibit dielectric properties; such as gas is dry air, while examples of solid dielectric materials include mica, ceramic, plastics and glass and even distilled water is considered to be a dielectric liquid.

1. The energy losses in a dielectric medium when the medium is exposed to a time-varying electric field.
2. The undesirable tendency of certain dielectrics to retain a portion of an electric charge after removal of the electric field.

The property of a material that determines how much electrostatic energy can be stored per unit volume of the material when unit voltage is applied.

An indication of the loss in dielectric property of a material: The dielectric loss becomes very important at high drive levels for transducers, as it indicates the amount of heat generation one can expect in a piezoelectric (a crystalline substance) the electrical property of which is changed by a pressure device.

The ability of a dielectric material to withstand high voltages without breaking down; expressed as the highest voltage required per millimeter of material thickness before a breakdown occurs: The dielectric strength is the maximum electrical potential gradient that a material can withstand without rupture; usually specified, in volts per millimeter of thickness.