- Apgar score
- a numerical measure of the health of a newborn
baby. One minute after birth (and at regular intervals thereafter through
the first moments of life) newborns are rated 0, 1, or 2 on five indicators
of health (respiratory effort, heart rate, skin color, muscle tone, and reflexive
response to smell). Possible scores therefore range from 0 to 10. The unit
is named for its inventor, the American anesthetist Virginia Apgar (1909-1974).
- API degree, API gravity
- see degree API.
- apostilb (asb)
- an MKS unit of luminance, equal to the brightness
produced by 1/pi candela per square meter or 10-4 lambert.
The name of the unit is pseudo-Greek for luminance; it combines the ancient
Greek stilbein, to "glitter" or "shine," with the prefix apo-,
"away from."
- apothecary weights
- a version of the troy weight system formerly
used by apothecaries (pharmacists). The troy pound, equal to 373.242 grams
or 13.165 72 avoirdupois ounces, is always divided into 12 ounces, each ounce
being equal to 480 grains. In the apothecary
system, the ounce is divided into 8 drams (60
grains) each containing 3 scruples (20 grains).
There is a parallel system of liquid volume measure in which the fluid
ounce is divided into 8 fluid drams (or fluidrams) each containing 3 fluid scruples. The apothecary system continued
in use into the early twentieth century, but it has been replaced everywhere
in pharmacy by the use of metric units. The abbreviation "ap." indicates apothecaries'
units, as in "oz. ap." or "dr. ap."
- arcminute (′ or min)
- a unit of angular measure, also called the minute of arc, equal to
60 arcseconds and to 1/60 degree. There are 21 600 arcminutes in a circle.
- arcsecond (″ or as or sec or s)
- a unit of angular measure, also called the second of arc, equal to
1/60 arcminute. One arcsecond is a very small angle indeed: there are 1 296
000 seconds in a circle. The SI defines s as the symbol
for the time unit and recommends ″ as the symbol for the arcsecond. The symbol as has become common in astronomy, where very small angles are stated
in milliarcseconds (mas).
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