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The oxygen enhancement ratio (OER) or oxygen enhancement effect in radiobiology refers to the enhancement of therapeutic or detrimental effect of ionizing radiation due to the presence of oxygen. This so-called oxygen effect [ 1 ] is most notable when cells are exposed to an ionizing radiation dose .
The best known explanation of the oxygen effect is the oxygen fixation hypothesis developed by Alexander in 1962, [9] which posited that radiation-induced non-restorable or "fixed" nuclear DNA lesions are lethal to cells in the presence of diatomic oxygen. [10] [11] Recent hypotheses include one based on oxygen-enhanced damage from first ...
Oxygen enhancement ratio, effect magnitude of ionizing radiation due to the presence of oxygen Oxygen Evolution Reaction , the formation of oxygen by electrochemical reduction of water Owner’s Equivalent Rent, an economic metric for housing prices often used in the calculation of market baskets
Tumor stroma and extracellular matrix in hypoxia. Tumor hypoxia is the situation where tumor cells have been deprived of oxygen.As a tumor grows, it rapidly outgrows its blood supply, leaving portions of the tumor with regions where the oxygen concentration is significantly lower than in healthy tissues.
At the time of the 720p launch, the YouTube player was changed from a 4:3 aspect ratio to a widescreen 16:9. [34] With this new feature, YouTube began a switchover to H.264/MPEG-4 AVC as its default video compression format. In November 2009, 1080p HD support was added.
Oxygen-15 is a radioisotope, often used in positron emission tomography (PET). It can be used in, among other things, water for PET myocardial perfusion imaging and for brain imaging. [ 20 ] [ 21 ] It has an atomic mass of 15.003 0656 (5) , and a half-life of 122.266(43) s .
A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas. Other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats such as scuba equipment, surface supplied diving equipment, recompression chambers, high-altitude mountaineering, high-flying aircraft, submarines ...
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