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In the most familiar acuity test, a Snellen chart is placed at a standard distance: 6 metres. At this distance, the symbols on the line representing "normal" acuity subtend an angle of five minutes of arc, and the thickness of the lines and of the spaces between the lines subtends one minute of arc. This line, designated 6/6 (or 20/20), is the ...
In the expression 6/x vision, the numerator (6) is the distance in metres between the subject and the chart and the denominator (x) the distance at which a person with 6/6 acuity would discern the same optotype. Thus, 6/12 means that a person with 6/6 vision would discern the same optotype from 12 metres away (i.e. at twice the distance).
Definition. Glomerular filtration rate (GFR) is the volume of fluid filtered from the renal (kidney) glomerular capillaries into the Bowman's capsule per unit time. [ 4] Central to the physiologic maintenance of GFR is the differential basal tone of the afferent (input) and efferent (output) arterioles (see diagram).
A surgical suture, also known as a stitch or stitches, is a medical device used to hold body tissues together and approximate wound edges after an injury or surgery. Application generally involves using a needle with an attached length of thread. There are numerous types of suture which differ by needle shape and size as well as thread material ...
In cardiac physiology, cardiac output ( CO ), also known as heart output and often denoted by the symbols , , or , [ 2] is the volumetric flow rate of the heart 's pumping output: that is, the volume of blood being pumped by a single ventricle of the heart, per unit time (usually measured per minute). Cardiac output (CO) is the product of the ...
Ejection fraction. An ejection fraction ( EF) is the volumetric fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or heartbeat ). It can refer to the cardiac atrium, [ 1] ventricle, [ 2] gall bladder, [ 3] or leg veins, [ 4] although if unspecified it usually refers to ...
every 4 hours quaque quarta hora q.6.h., q6h every 6 hours quaque sexta hora q.8.h., q8h every 8 hours quaque octava hora q.a.m., qAM, qam every morning: quaque ante meridiem q.d., qd every day / daily quaque die q.h.s., qhs every night at bedtime quaque hora somni q.d.s, qds, QDS 4 times a day quater die sumendum q.i.d, qid 4 times a day
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million ( ppm ...