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The area where blood collects between the tunica intima and the media is called a false lumen, and the true lumen is the regular lumen of the blood vessel. Since high pressure is a cause of aortic dissection, it’s no surprise that the aorta is the prime target for this problem. So what causes aortic dissections?
The lumen (symbol: lm) is the unit of luminous flux, a measure of the perceived power of visible light emitted by a source, in the International System of Units (SI). Luminous flux differs from power ( radiant flux ), which encompasses all electromagnetic waves emitted, including non-visible ones such as thermal radiation ( infrared ).
Arterial dissections become life-threatening when growth of the false lumen prevents perfusion of the true lumen and the related end organs. For example, in an aortic dissection, if the left subclavian artery orifice were distal to the origin of the dissection, then the left subclavian would be said to be perfused by the false lumen, while the left common carotid (and its end organ, the left ...
An echocardiogram displaying the true lumen and false lumen of an aortic dissection: In the image to the left, the intimal flap can be seen separating the two lumens. In the image to the right, color flow during ventricular systole suggests that the upper lumen is the true lumen.
Luminous flux (in lumens) is a measure of the total amount of light a lamp puts out. The luminous intensity (in candelas) is a measure of how bright the beam in a particular direction is. If a lamp has a 1 lumen bulb and the optics of the lamp are set up to focus the light evenly into a 1 steradian beam, then the beam would have a luminous ...
Luminous efficacy can be normalized by the maximum possible luminous efficacy to a dimensionless quantity called luminous efficiency.The distinction between efficacy and efficiency is not always carefully maintained in published sources, so it is not uncommon to see "efficiencies" expressed in lumens per watt, or "efficacies" expressed as a percentage.
A tea light-type candle, imaged with a luminance camera; false colors indicate luminance levels per the bar on the right (cd/m 2). Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. [1]
To help compare different orders of magnitude, the following list describes various source in lux, which is a lumen per square metre. Factor Multiple Value