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The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on a spherical Earth, so the actual Earth circumference is very near 21600nmi. A minute of arc is π/10800 of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol ″, [ 2 ] is 1/60 of an arcminute, 1/3600 of ...
Counts per minute (abbreviated to cpm) is a measure of the detection rate of ionization events per minute. Counts are only manifested in the reading of the measuring instrument, and are not an absolute measure of the strength of the source of radiation. Whilst an instrument will display a rate of cpm, it does not have to detect counts for one ...
Geographic coordinate conversion has applications in cartography, surveying, navigation and geographic information systems. In geodesy, geographic coordinate conversion is defined as translation among different coordinate formats or map projections all referenced to the same geodetic datum. [1] A geographic coordinate transformation is a ...
D-value (microbiology) In microbiology, in the context of a sterilization procedure, the D-value or decimal reduction time (or decimal reduction dose) is the time (or dose of an antimicrobial drug) required, at a given condition (e.g. temperature) or set of conditions, to achieve a one- log reduction, that is, to kill 90% of relevant ...
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, 10 ...
Angular diameter: the angle subtended by an object. The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens).
The large dial shows the ten hours of the decimal day in Arabic numerals, while the small dial shows the two 12-hour periods of the standard 24-hour day in Roman numerals. Decimal time is the representation of the time of day using units which are decimally related. This term is often used specifically to refer to the French Republican calendar ...
For 6/6 = 1.0 acuity, the size of a letter on the Snellen chart or Landolt C chart is a visual angle of 5 arc minutes (1 arc min = 1/60 of a degree), which is a 43 point font at 20 feet. [10] By the design of a typical optotype (like a Snellen E or a Landolt C), the critical gap that needs to be resolved is 1/5 this value, i.e., 1 arc min.