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Flight-time equivalent dose (FED) is an informal unit of measurement of ionizing radiation exposure. Expressed in units of flight-time (i.e., flight-seconds, flight-minutes, flight-hours), one unit of flight-time is approximately equivalent to the radiological dose received during the same unit of time spent in an airliner at cruising altitude.
[9] [failed verification] Each degree was subdivided into 60 minutes and each minute into 60 seconds. [10] [11] Thus, one Babylonian degree was equal to four minutes in modern terminology, one Babylonian minute to four modern seconds, and one Babylonian second to 1 / 15 (approximately 0.067) of a modern second.
This is a pure coincidence, as the metre was originally defined as 1 / 10 000 000 of the distance between the Earth's pole and equator along the surface at sea level, and the Earth's circumference just happens to be about 2/15 of a light-second. [39] It is also roughly equal to one foot per nanosecond (the actual number is 0.9836 ft/ns).
The following table shows the probability for some other values of n (for this table, the existence of leap years is ignored, and each birthday is assumed to be equally likely): The probability that no two people share a birthday in a group of n people. Note that the vertical scale is logarithmic (each step down is 10 20 times less likely).
One sievert equals 100 rem, which is an older, CGS radiation unit. Conventionally, deterministic health effects due to acute tissue damage that is certain to happen, produced by high dose rates of radiation, are compared to the physical quantity absorbed dose measured by the unit gray (Gy).
One example is represented by the conditions in the first 10 −43 seconds of our universe after the Big Bang, approximately 13.8 billion years ago. The four universal constants that, by definition, have a numeric value 1 when expressed in these units are: c, the speed of light in vacuum, G, the gravitational constant, ħ, the reduced Planck ...
Because the square of a standard normal distribution is the chi-squared distribution with one degree of freedom, the probability of a result such as 1 heads in 10 trials can be approximated either by using the normal distribution directly, or the chi-squared distribution for the normalised, squared difference between observed and expected value.
An illustration of light sources from magnitude 1 to 3.5, in 0.5 increments. In astronomy, magnitude is a measure of the brightness of an object, usually in a defined passband.