sphero-, spher-, -sphere-
(Greek: ball, round, around; globe, global; body of globular form; by extension, circular zone, circular area)
2. The spherical region of space dominated by the gravitational field of a celestial body.
2. A spherical region around the sun, approximately 100 astronomical units in radius, outside which interstellar space begins.
3. The region of space through which the solar wind extends and the region around the sun outside of which the sun's influence is negligible and interstellar space begins.
2. One half of a sphere or of anything spherical in shape.
3. Either of the two halves of a celestial sphere that is north or south of the celestial equator.
4. One half of a sphere, formed by a plane that passes through the center of the sphere.
2. Excision of one cerebral hemisphere; undertaken for malignant tumors, intractable epilepsy usually associated with infantile hemiplegia due to birth injury, and other cerebral conditions.
Surgeons have performed hemispherectomies hundreds of times for disorders that can not be controlled any other way
- The surgery has no apparent effect on personality or memory.
- People can survive and function fairly well after the procedure although they may have some physical disabilities; such as, a significant loss of the function on one side of the body.
- A person can walk, run, dance, or skip; but some lose use of the hand opposite the hemisphere that was removed.
- Sometimes, if the left side of the brain is taken out, most people have problems with their speech; however, the younger a person is after a hemispherectomy, the less speech disability the person is likely to have.
- The surgery consists of two forms: "anatomical hemispherectomic removal" of an entire hemisphere of the brain or "functional hemispherectomies" that take out only parts of a hemisphere.
- Doctors often prefer anatomical hemispherectomies because "leaving even a little bit of brain behind can lead seizures to return", stated neurologist John Freeman of Johns Hopkins, which specializes in the procedure.
- The functional hemispherectomies, which U.C.L.A. surgeons usually perform, lead to less blood loss.
- A recent study found that 86 percent of the 111 children who underwent the procedure at Johns Hopkins between 1975 and 2001 are either seizure-free or have non-disabling seizures that do not require medication.
- One reason for the procedure is to stop debilitating seizures and today brain surgeons perform hemispherectomies on patients who undergo dozens of seizures daily which resist all medication and result from conditions that primarily afflict one hemisphere of the brain.
- The seizures are often progressive and damage the rest of the brain if not treated.
- A study found that children who underwent a hemispherectomy often improved academically [and physically] once their seizures stopped.
- Hemispherectomy is one of the most drastic kinds of brain surgery and it is done only when not doing so will be worse.
Individual hemisphericity was erroneously thought to be located somewhere on a gradient between right and left brain dominance with most people being intermediate.2. The bias in thinking orientation, behavioral style, and personality resulting from the inherent laterality of one's sole Executive system within the asymmetric bilateral brain.
Thus, depending upon which brain side "the one and only you" inherently is located, someone is either a left or a right brain oriented person.
2. The portion of the earth that is water, including liquid water, ice, and water vapor on the surface, underground, or in the atmosphere.
The internet, books, and other media are considered to be part of the ideosphere.
2. An encircling layer of electronic and typographical smog composed of cliches from journalism, entertainment, advertising and government.
3. The whole informational environment constituted by all informational entities, their properties, interactions, processes, and mutual relations.
2. A region of the earth's atmosphere where ionization caused by incoming solar radiation affects the transmission of radio waves.
It extends from a height of 70 kilometers (43 miles) to 400 kilometers (250 miles) above the surface.3. A section in the earth's atmosphere, beginning at an altitude of 70-80 kilometers and extending to an indefinite height, in which free electrons and ions produced by solar radiation are abundant and affect certain radio waves that propagate through this region.
Ionosphere and Magnetosphere
The ionosphere and the magnetosphere consist of regions of the earth’s atmosphere in which the number of electrically charged particles—ions and electrons—are large enough to affect the propagation of radio waves.
The charged particles are created by the action of extraterrestrial radiation (mainly from the sun) on neutral atoms and molecules of air.
The ionosphere begins at a height of about 50 kilometers (30 miles) above the surface, but it is most distinct and important above 80 kilometers (50 miles).
In the upper regions of the ionosphere, beginning several hundred kilometers above earth’s surface and extending tens of thousands of kilometers into space, is the magnetosphere, a region where the behavior of charged particles is strongly affected by the magnetic fields of the earth and the sun.
Much of the early research on the ionosphere was carried out by radio engineers and was stimulated by the need to define the factors influencing long-range radio communication.
It is in the magnetosphere that the spectacular displays of the aurora borealis and aurora australis take place.
The magnetosphere also contains the Van Allen radiation belts, where highly energized protons and electrons travel back and forth between the poles of earth’s magnetic field.
The name ionosphere was introduced first in the 1920's and was formally defined in 1950 by a committee of the Institute of Radio Engineers as "the part of the earth's upper atmosphere where ions and electrons are present in quantities sufficient to affect the propagation of radio waves."
Subsequent research has focused on understanding the ionosphere as the environment for earth-orbiting satellites and, in the military arena, for ballistic missile flight.
Scientific knowledge of the ionosphere has grown tremendously, fueled by a steady stream of data from spacecraft-borne instruments and enhanced by measurements of relevant atomic and molecular processes in the laboratory.