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The proof of concept of BOLD-contrast imaging was provided by Seiji Ogawa and Colleagues in 1990, following an experiment which demonstrated that an in vivo change of blood oxygenation could be detected with MRI. [6] In Ogawa's experiments, blood-oxygenation-level–dependent imaging of rodent brain slice contrast in different components of the ...
BOLD contrast depends on blood flow, which is both sluggish in response to stimulus and subject to noisy influences. Other biomarkers now looked at to provide better contrast include temperature, acidity/alkalinity (pH), calcium-sensitive agents, neuronal magnetic field, and the Lorentz effect.
In some literature articles, the terms "mechanism of action" and "mode of action" are used interchangeably, typically referring to the way in which the drug interacts and produces a medical effect. However, in actuality, a mode of action describes functional or anatomical changes, at the cellular level, resulting from the exposure of a living ...
A mechanism of action of a chemical could be "binding to DNA" while its broader mode of action would be "transcriptional regulation". [3] However, there is no clear consensus and the term mode of action is also often used, especially in the study of pesticides, to describe molecular mechanisms such as action on specific nuclear receptors or ...
A contrast effect is the enhancement or diminishment, relative to normal, of perception, cognition or related performance as a result of successive (immediately previous) or simultaneous exposure to a stimulus of lesser or greater value in the same dimension. (Here, normal perception, cognition or performance is that which would be obtained in ...
Contrast is the antonym of simile. In poetic compositions, it is common for poets to set out an elaborate contrast or elaborate simile as the argument. For example, John Donne and the metaphysical poets developed the conceit as a literary device, where an
James defined what affirmative action is in its most basic form. "(It) is a policy that encourages state institutions to take affirmative action to make sure their processes are fair," she explains.
Contrast sensitivity is typically expressed as the reciprocal of the threshold contrast for detection of a given pattern (i.e., 1 ÷ contrast threshold). [16] Using the results of a contrast sensitivity exam, a contrast sensitivity curve can be plotted, with spatial frequency on the horizontal, and contrast threshold on the vertical axis.