spectral index

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spectral index

The index, α, expressing how the flux density (S) of a radio source varies with frequency (ν). The spectrum is taken to be a power law so that either S ∝ να or S ∝ ν–α. Because α is frequently stated without its sign, it is important to be clear which definition is being used in every case. See also power-law spectrum; radio-source spectrum.
References in periodicals archive ?
Both amplitudes and spectral indices of power-law noise show a spatial correlation for Up component.
Remote estimation of crop chlorophyll content using spectral indices derived from hyperspectral data, IEEE T Geosci.
Localisation also enables measurement of their true fluxes, polarisation and spectral indices which are all crucial to identify their origin.
Other factors that could also contribute to the inconsistent behaviour of spectral indices and MCFV are crosstalk and cancellation.
The colour Doppler scoring and spectral indices (RI, PI) were noted and characterisation of the masses done by Sassone Score (Table 1) and Caruso Score (Table 2) and results correlated with surgical and histopathology findings.
6,7 Work done on the population of Belgium documented that HRV indices, denoting vagal activity, were not significantly different between men and women, whereas the spectral indices, LF power and LF/HF ratio were significantly higher in men.
This is because relatively low chlorophyll contents are sufficient to saturate absorption in the 660-680 nm region, thus reducing the sensitivity to high chlorophyll contents of spectral indices based on these wavelengths.
2005, The utility of spectral indices from Landsat ETM+ for measuring structure and composition of tropical dry forest.
This is another important reason to incorporate the use of the NDVI, or similar spectral indices, to ensure more consistent and accurate delineation of vegetation community type as related to percent cover.
We thought to review the role of conventional, nonlinear and novel spectral indices of HRV in prediction of sudden cardiac death in patients with myocardial infraction and heart failure.
The relationship between spectral indices (RARS) and the SPAD chlorophyll meter values were never verified at the genotypic level.

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