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The CCU decided to define the SI unit of absorbed radiation as energy deposited by reabsorbed charged particles per unit mass of absorbent material, which is how the rad had been defined, but in MKS units it would be equivalent to the joule per kilogram. This was confirmed in 1975 by the 15th CGPM, and the unit was named the "gray" in honour of ...
The cardiac index (CI) is a hemodynamic measure that represents the cardiac output (CO) of an individual divided by their body surface area (BSA), expressed in liters per minute per square meter (L/min/m²). This parameter provides a more accurate assessment of heart function relative to the size of the individual, as opposed to absolute ...
[1] [2] It is usually given in units of becquerel per kilogram (Bq/kg), but another commonly used unit of specific activity is the curie per gram (Ci/g). In the context of radioactivity , activity or total activity (symbol A ) is a physical quantity defined as the number of radioactive transformations per second that occur in a particular ...
The curie (symbol Ci) is a non-SI unit of radioactivity originally defined in 1910. According to a notice in Nature at the time, it was to be named in honour of Pierre Curie , [ 1 ] but was considered at least by some to be in honour of Marie Curie as well, [ 2 ] and is in later literature considered to be named for both.
Year SI equivalent Activity (A) becquerel: Bq s −1: 1974 SI unit curie: Ci 3.7 × 10 10 s −1: 1953 3.7 × 10 10 Bq rutherford: Rd 10 6 s −1: 1946 1 000 000 Bq Exposure (X) coulomb per kilogram: C/kg C⋅kg −1 of air 1974 SI unit röntgen: R esu / 0.001 293 g of air 1928 2.58 × 10 −4 C/kg: Absorbed dose (D) gray: Gy J⋅kg −1: 1974 ...
The duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. metre: m length, , , etc. The distance travelled by light in vacuum in 1 / 299 792 458 second. kilogram [n 1]
About 31,709 years. megaannum: 10 6 yr: Also called "megayear". 1000 millennia (plural of millennium), or 1 million years (in geology, abbreviated as Ma). petasecond: 10 15 s: About 31 709 791 years. galactic year: 2.3 × 10 8 yr: The amount of time it takes the Solar System to orbit the center of the Milky Way Galaxy (approx 230 000 000 years ...
1 Bq = 1 s −1. A special name was introduced for the reciprocal second (s −1) to represent radioactivity to avoid potentially dangerous mistakes with prefixes.For example, 1 μs −1 would mean 10 6 disintegrations per second: (10 −6 s) −1 = 10 6 s −1, [4] whereas 1 μBq would mean 1 disintegration per 1 million seconds.