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  2. Hubble's law - Wikipedia

    en.wikipedia.org/wiki/Hubble's_law

    In this form H 0 = 7%/Gyr, meaning that at the current rate of expansion it takes a billion years for an unbound structure to grow by 7%. Although widely attributed to Edwin Hubble , [ 6 ] [ 7 ] [ 8 ] the notion of the universe expanding at a calculable rate was first derived from general relativity equations in 1922 by Alexander Friedmann .

  3. Kinetic isotope effect - Wikipedia

    en.wikipedia.org/wiki/Kinetic_isotope_effect

    A primary kinetic isotope effect (PKIE) may be found when a bond to the isotopically labeled atom is being formed or broken. [3] [4]: 427 Depending on the way a KIE is probed (parallel measurement of rates vs. intermolecular competition vs. intramolecular competition), the observation of a PKIE is indicative of breaking/forming a bond to the isotope at the rate-limiting step, or subsequent ...

  4. Ratio - Wikipedia

    en.wikipedia.org/wiki/Ratio

    For example, the ratio one minute : 40 seconds can be reduced by changing the first value to 60 seconds, so the ratio becomes 60 seconds : 40 seconds. Once the units are the same, they can be omitted, and the ratio can be reduced to 3:2. On the other hand, there are non-dimensionless quotients, also known as rates (sometimes also as ratios).

  5. Related rates - Wikipedia

    en.wikipedia.org/wiki/Related_rates

    describes the relationship between x, y and h, for a right triangle. Differentiating both sides of this equation with respect to time, t, yields. Step 3: When solved for the wanted rate of change, dy / dt, gives us. Step 4 & 5: Using the variables from step 1 gives us: Solving for y using the Pythagorean Theorem gives:

  6. Signal-to-noise ratio - Wikipedia

    en.wikipedia.org/wiki/Signal-to-noise_ratio

    Definition. One definition of signal-to-noise ratio is the ratio of the power of a signal (meaningful input) to the power of background noise (meaningless or unwanted input): where P is average power. Both signal and noise power must be measured at the same or equivalent points in a system, and within the same system bandwidth.

  7. Shunt equation - Wikipedia

    en.wikipedia.org/wiki/Shunt_equation

    The following equation, provides the ratio of the pulmonary blood flow divided by the systemic blood flow and relates to any type of shunt (intracardiac or extracardiac) using variables that can be easily attained in a cardiac catheterization laboratory. Note that the abbreviations are different from the aforementioned equation to reflect the ...

  8. Golden ratio - Wikipedia

    en.wikipedia.org/wiki/Golden_ratio

    The golden ratio φ and its negative reciprocal −φ −1 are the two roots of the quadratic polynomial x 2 − x − 1. The golden ratio's negative −φ and reciprocal φ −1 are the two roots of the quadratic polynomial x 2 + x − 1. The golden ratio is also an algebraic number and even an algebraic integer. It has minimal polynomial

  9. Receiver operating characteristic - Wikipedia

    en.wikipedia.org/wiki/Receiver_operating...

    The true-positive rate is also known as sensitivity, recall or probability of detection. [1] The false-positive rate is also known as the probability of false alarm [1] and equals (1 − specificity). The ROC is also known as a relative operating characteristic curve, because it is a comparison of two operating characteristics (TPR and FPR) as ...