Alternative biochemistry collectively refers to an assortment of astrobiology theories and hypotheses in which life is based on chemical systems other than those used by currently known forms of life. Proponents of such theories sometimes use the expression carbon chauvinism to disparage the assumption that carbon molecules are necessarily the basis for all life. Up to this point, however, no non-carbon based life-form has been discovered.
Alternative biochemistry - Silicon biochemistry.
The most com ...
Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. The spacecraft consists of two main elements: the Cassini orbiter, named after the Italian-French astronomer Giovanni Domenico Cassini, and the Huygens probe, named after the Dutch astronomer Christiaan Huygens. It was launched on October 15, 1997 and entered Saturn's orbit on July 1, 2004. On December 25, 2004 the probe separated from the orbiter at approximately 02:00 UTC, with deployment confirmed by th ...
Antony Hewish (born Fowey, Cornwall, May 11, 1924) is a British radio astronomer who won the Nobel Prize for Physics in 1974 (together with fellow radio-astronomer Martin Ryle) for his role in the discovery of pulsars. He was also awarded the Eddington Medal of the Royal Astronomical Society in 1969.
His undergraduate degree at the University of Cambridge was interrupted by war service at the Royal Aircraft Establishment, and at the Telecommunications Research Establishment where he worked with Martin Ryle. Returning to Cambrid ...
The polar aurora is a glow observed in the night sky in the polar zone. It is also known as "northern lights" or "aurora borealis," Latin for "northern dawn" since (in Europe especially) it often appears as a reddish glow on the northern horizon, as if the sun were rising from an unusual direction. Aurora borealis most often occurs from September to October and March to April. Its southern counterpart "aurora australis," has identical properties, so scientists prefer "polar au ...
A Birkeland current generally refers to any electric current in a space plasma, but more specifically when charged particles in the current follow magnetic field lines. They are caused by the movement of a plasma perpendicular to a magnetic field. Birkeland currents often show filamentary, or twisted "rope-like" magnetic structure. They are sometimes referred to as field-aligned currents.
Originally Birkeland currents referred to electric currents that contribute to the aurora, caused by the interaction of the pla ...
An antibody is a protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target. Production of antibodies is referred to as the humoral immune system.
Antibody - Definition.
Immunoglobulins are glycoproteins in the immunoglobulin superfamily that function as antibodies. The terms antibody and immunoglobulin are often used interchangeably. They are found in the blood and tissue fluids, as w ...
The BFG9000 is a fictional futuristic weapon found in the computer games Doom, Doom II, Doom 3, and Doom 3: Resurrection of Evil. The BFG9000 appears as a large, solid metal gun that fires big balls of green plasma. The most powerful in the game, it is capable of destroying nearly any player or enemy with a single hit. Most subsequent first-person shooters implemented similar weapons, but few of them were quite as notorious as the BFG9000. Quake II and Quake III Arena pay homage to the BFG9000 with a p ...
An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, similar to the instant spark, resulting from a current flowing through normally nonconductive media such as air. A slightly archaic term is voltaic arc as used in the phrase "voltaic arc lamp".
The various shapes of electric arc are emergent properties of nonlinear patterns of current and electric field. The arc occurs in the gas-filled space between two conductive electrodes (often made of carbon) and it results in a very high temperature, c ...
Ball lightning is a natural phenomenon, or debatably, a pseudoscientific theory. It is sometimes associated with thunderstorms. It takes the form of a long-lived, glowing, floating object, as opposed to the short-lived arcing between two points commonly associated with lightning. An early attempt to explain ball lightning was recorded by Nikola Tesla on March 5, 1904 (Electrical World and Engineer). [1]
There is dispute on the existence of ball lightning. Many in the scientific community seek be ...
Apollo 8 was the second manned mission of the Apollo space program, in which Commander Frank Borman, Command Module Pilot James Lovell and Lunar Module Pilot William Anders became the first humans to leave Earth orbit and to orbit around the Moon. It was also the first manned launch of the Saturn V rocket.
NASA prepared for the mission in only four months. The hardware involved had only been used a few times—the Saturn V had launched only twice before, and the Apollo spacecraft had only just finished its first manned m ...
Blood tests are laboratory tests done on blood to gain an appreciation of disease states and the function of organs. Since blood flows throughout the body, acting as a medium for providing oxygen and other nutrients, and drawing waste products back to the excretory systems for disposal, the state of the bloodstream affects, or is affected by, many medical conditions. For these reasons, blood tests are the most commonly performed medical tests. Blood is obtained from a patient by venipunct ...
A cerebral hemorrhage or hemorrhagic stroke is a form of stroke that occurs when a blood vessel in the brain ruptures or bleeds. Hemorrhagic strokes are deadlier than their more common counterpart, ischemic strokes. Like ischemic strokes, hemorrhagic strokes interrupt the brain's blood supply, but in addition, blood irritates brain tissue, disrupting the delicate chemical balance, and, if the bleeding continues, the increased intracranial pressure can crush brain t ...
Zeaxanthin is one of the two carotenoids contained within the retina.
Within the central macula, zeaxanthin is the dominant component, whereas in the peripheral retina, lutein predominates.
Lutein and zeaxanthin have identical chemical formulas and are isomers, but they are not stereoisomers. The main difference between them is in the location of a double bond in one of the end rings. This difference gives lutein ...
Charge carrier denotes in physics a free (mobile, unbound) particle carrying an electric charge. Examples are electrons and ions. In semiconductor physics, the travelling vacancies in the valance-band electron population (holes) are treated as charge carriers.
In ionic solutions, the charge carriers are the dissolved cations and anions. Similarly, cations and anions of the dissociated liquid serve as charge carriers in liquids and melted ionic solids (see eg. the Hall-Herou ...
edit
In cosmology, the cosmic microwave background radiation (most often abbreviated CMB but occasionally CMBR, CBR or MBR) is a form of electromagnetic radiation discovered in 1965. It has a thermal black-body spectrum which peaks in the microwave range. Most cosmologists consider the cosmic microwave background radiation to be the best evidence for the hot big bang model of the universe.
Cosmic microwave background radiation - Features.
The cosmic microwav ...
Blood donation is a process by which a blood donor voluntarily has blood drawn for storage in a blood bank for subsequent use in a blood transfusion.
To understand the importance of the availability of a sustainable donated blood supply, the catch-cry of the Australian Red Cross Blood Service is, "80% of Australians will need blood in their lifetime, but less than 3% of Australians give blood each year."
Blood donations may be scheduled at local centres, or at times a "blood drive" will occur. These are events whe ...
Androstenedione is a 19-carbon steroid hormone produced in the adrenal glands and the gonads as an intermediate step in the biochemical pathway that produces the androgen testosterone and the estrogens estrone and estradiol. It is the common precursor of male and female sex hormones. Some androstenedione is also secreted into the plasma, and may be converted in peripheral tissues to testosterone and estrogens.
Androstenedione originates either from the conversion of dehydroepiandrosterone or from 17-hydroxyprogesterone. It i ...
This page is a candidate to be copied to Wiktionary.
The information in this article appears to be more suited for a dictionary rather than an encyclopedia. Wikipedia is not a dictionary, but Wiktionary is. Please verify that this article meets the Wiktionary criteria for inclusion. If this article can be modified to be more than a dictionary entry, please do so and remove this message.
Blood volume is a term describing the amount of blood (including both red blood cells and plasma) in a person's circulatory system
Bremsstrahlung, (from the German bremsen, to brake and Strahlung, radiation), is electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when deflected by another charged particle, such as an atomic nucleus. The term is also used to refer to the process of producing the radiation. Bremsstrahlung has a continuous spectrum. The phenomenon was discovered by Nikola Tesla during high frequ ...
The coagulation of blood is a complex process during which blood forms solid clots. It is an important part of haemostasis whereby a damaged blood vessel wall is covered by a fibrin clot to stop hemorrhage and aid repair of the damaged vessel. Disorders in coagulation can lead to increased hemorrhage and/or thrombosis and embolism.
Coagulation is extremely similar in all mammals, with all mammals using a combined cellular and serine protease mechanism. The system in humans is the most extensively researched and therefore the be ...
