magnet-, magneto- +

(Greek: Magnesian [stone]; Magnesia having been a mineral-rich region of Thessaly)

aeromagnetics
The scientific study of the earth's magnetic characteristics as measured from the air.
biomagnetism
1. The magnetic field created by a living organism; such as, animal magnetism.
2. The effect of an external magnetic field on living organisms.
diamagnetic
1. Relating to a substance that is repelled by a magnet.
2. A reference to a class of substances; such as, bismuth and copper, whose permeability is less than that of a vacuum.

In a magnetic field, their induced magnetism is in a direction opposite to that of iron.

diamagnetism
A phenomenon exhibited by materials like copper or bismuth that become magnetized in a magnetic field with a polarity opposite to the magnetic force; unlike iron they are slightly repelled by a magnet.
diffusion tensor imaging (DTI)
1. Measuring the movement of water in the brain, detecting areas where the normal flow of water is disrupted.

A disrupted flow of water indicates where there could be an underlying abnormality in the brain.

2. A new type of magnetic resonance technology which has, among other things, for the first time shown "white matter" in action, revealing its role in the brain.

Although gray matter (composed of neurons) does the brain's thinking and calculating, white matter (composed of myelin-coated axons, or long fibers of nerve cells), control the signals which neurons share, co-ordinating how well brain regions work together.

Diffusion tensor imaging (DTI) is done with the same kind of magnetic resonance imaging (MRI) machines found in hospitals; however, it involves a different type of magnetic field and different algorithms to create the many brain-image slices that are assembled into a three-dimensional picture.

diffusion weighted imaging (DWI)
Magnetic resonance technology presenting images of the body in which areas of rapid proton diffusion can be distinguished from areas with slow diffusion.

DWI, or diffusion weighted imaging, has been demonstrated to be more sensitive for the early detection of stroke than standard pulse sequences and is closely related to temperature mapping.

electromagnet
1. A temporary magnet made by coiling wire around an iron core; when current flows in the coil the iron becomes a magnet.
2. A magnet consisting of a core, often made of soft iron, that is temporarily magnetized by an electric current flowing through a coil that surrounds it.
3. A coil of wire usually wound on a soft iron or steel core.

When current is passed through the coil a magnetic field is generated and the core provides an easy path for the magnetic lines of force. This concentrates the electric field in the core.

electromagnetic
1. Created by or relating to electromagnetism; that is, the interaction of electricity and magnetism.
2. Involving or relating the interaction of electric and magnetic fields, both static and dynamic.
3. A reference to magnetism that is induced by an electric current.
4. Pertaining to radiation; such as, light, microwaves, X-rays, gamma rays, or radio waves.
5. Referring to the combined electric and magnetic fields associated with radiation or movements of electrons or other charged particles through conductors or space.
electromagnetic library security system
A security system that uses magnetic strips in objects that are read by a scanner in an antenna or a sensitizer/desensitizer.
ferromagnetic
1. Characteristic of substances; such as, iron, nickel, or cobalt and various alloys that exhibit extremely high magnetic permeability, a characteristic saturation point, and magnetic hysteresis (delayed response by an object to changes in the forces acting on it, especially magnetic forces).
2. With the property of ferromagnetism.

Iron, cobalt, and nickel are ferromagnetic metals.

ferromagnetism
1. A phenomenon exhibited by materials like iron (nickel or cobalt) that become magnetized in a magnetic field and retain their magnetism when the field is removed.
2. The property of certain metals and alloys; especially, those of the iron group, rare-earth, and acitinide series, that are capable of spontaneous magnetic polarization, resulting in drastic magnetic effects.

These materials are strongly attracted to magnets and are used in permanent magnets and various ceramic compounds.

geomagnetic
1. Relating to geomagnetism or the magnetic properties of the earth.
2. Having properties, or characteristics, of geomagnetism.

The study of the sources, configurations, and changes in the earth's magnetic field and the study and interpretation of the remaining magnetism in rocks as a result of the earth's magnetic field when the rocks were formed which is known as paleomagnetism.

geomagnetic elements
The components of the geomagnetic field at the surface of the earth.
geomagnetic field
The magnetic field observed in and around the earth.

The intensity of the magnetic field at the earth's surface is approximately 0.32 gauss at the equator and 0.62 gauss at the north pole.

A gauss equivalent to 1 maxwell per square centimeter and a maxwell is equivalent to the flux that produces one abvolt in a one-turn circuit when the flux is reduced to zero at a uniform rate in one second; while a flux is the electric or magnetic field lines of force that traverse a given cross-sectional area.

geomagnetic storm
A world-wide disruption of the earth's magnetic field, distinct from regular diurnal variations; caused by ionic disturbances from solar events.