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An electroretinogram (ERG) test performed in 2014. A historical photo of a patient undergoing an electroretinogram. Clinically used mainly by ophthalmologists the electroretinogram (ERG) is used for the diagnosis of various retinal diseases. [2] Inherited retinal degenerations in which the ERG can be useful include: [citation needed]
The roentgen or röntgen (/ ˈ r ɛ n t ɡ ə n,-dʒ ə n, ˈ r ʌ n t-/; [2] symbol R) is a legacy unit of measurement for the exposure of X-rays and gamma rays, and is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air (statcoulomb per kilogram).
The lower range value of 83.8 ergs was the value in air corresponding to wet tissue. [7] The rep was commonly used until the 1960s, [8] but was gradually displaced by the rad starting in 1954 and later the gray starting in 1977.
R ∗ = 8.314 32 × 10 3 N⋅m⋅kmol −1 ⋅K −1 = 8.314 32 J⋅K −1 ⋅mol −1. Note the use of the kilomole, with the resulting factor of 1000 in the constant. The USSA1976 acknowledges that this value is not consistent with the cited values for the Avogadro constant and the Boltzmann constant. [13]
100 erg/g The rad is a unit of absorbed radiation dose , defined as 1 rad = 0.01 Gy = 0.01 J/kg. [ 1 ] It was originally defined in CGS units in 1953 as the dose causing 100 ergs of energy to be absorbed by one gram of matter.
An erg is the amount of work done by a force of one dyne exerted for a distance of one centimetre. In the CGS base units, it is equal to one gram centimetre-squared per second-squared (g⋅cm 2 /s 2). It is thus equal to 10 −7 joules or 100 nanojoules in SI units. 1 erg = 10 −7 J = 100 nJ; 1 erg = 10 −10 sn⋅m = 100 psn⋅m = 100 ...
The SAR value is then measured at the location that has the highest absorption rate in the entire head, which in the case of a mobile phone is often as close to the phone's antenna as possible. Measurements are made for different positions on both sides of the head and at different frequencies representing the frequency bands at which the ...
An R 2 of 1 indicates that the regression predictions perfectly fit the data. Values of R 2 outside the range 0 to 1 occur when the model fits the data worse than the worst possible least-squares predictor (equivalent to a horizontal hyperplane at a height equal to the mean of the observed data). This occurs when a wrong model was chosen, or ...