Search results
Results From The WOW.Com Content Network
Due to the very slow pole motion of the Earth, the Celestial Ephemeris Pole (CEP, or celestial pole) does not stay still on the surface of the Earth.The Celestial Ephemeris Pole is calculated from observation data, and is averaged, so it differs from the instantaneous rotation axis by quasi-diurnal terms, which are as small as under 0.01" (see [6]).
The Sub-bureau for Rapid Service and Predictions of Earth Orientation Parameters of the IERS, located at the United States Naval Observatory, monitors the Earth's rotation. Part of its mission involves the determination of a time scale based on the current rate of the rotation of the Earth. Other services of IERS are at the Paris Observatory.
Constructed with input data under the form of time series of station positions and Earth Orientation Parameters. [5] This version introduces extra parameters to describe the year-periodic motion of the stations: A (amplitude) and φ (phase) per-axis. This sort of seasonal variation has an amplitude of around 1 cm and is attributed to non-tidal ...
Polar motion of the Earth is the motion of the Earth's rotational axis relative to its crust. [2]: 1 This is measured with respect to a reference frame in which the solid Earth is fixed (a so-called Earth-centered, Earth-fixed or ECEF reference frame). This variation is a few meters on the surface of the Earth.
The angular velocity of the Earth is defined to be ω = 72.921 15 × 10 −6 rad/s. [11] This leads to several computed parameters such as the polar semi-minor axis b which equals a × (1 − f) = 6 356 752.3142 m, and the first eccentricity squared, e 2 = 6.694 379 990 14 × 10 −3. [11]
A man with pellagra, which is caused by a chronic lack of vitamin B 3 in the diet. Severe deficiency of niacin in the diet causes the disease pellagra, characterized by diarrhea, sun-sensitive dermatitis involving hyperpigmentation and thickening of the skin (see image), inflammation of the mouth and tongue, delirium, dementia, and if left untreated, death. [7]
Example of a label showing the amount of niacin (Vitamin B3), and specifying to be niacinamide in the ingredient section.. The United States Government adopted the terms niacin and niacinamide in 1942 as alternate names for nicotinic acid and nicotinamide, respectively, and encouraged their use in nontechnical contexts to avoid the public’s confusing them with the nearly unrelated (and toxic ...
This astronomical unit is approximately the mean distance between the Earth and the Sun. The value of k is the angular velocity in radians per day ( i.e. the daily mean motion ) of an infinitesimally small mass that moves around the Sun in a circular orbit at a distance of 1 AU.