We apply the method of principal component analysis to a sample of simple stellar population to select some age sensitive spectral indices. Besides the well-known age sensitive index, Hβ, we find some other spectral indices have great potential to determine the age of stellar population, such as G4300, Fe4383, C24668, and Mgb. In addition, we find these spectral indices sensitivity to age depen...

We present results from a study of X-shaped sources based on observations using the Giant Metrewave Radio Telescope (GMRT). These observations were motivated by our low frequency study of 3C 223.1 (Lal & Rao 2005), an X-shaped radio source, which showed that the wings (or low-surface-brightness jets) have flatter spectral indices than the active lobes (or high-surface-brightness jets), a result...

Primordial spectral indices are calculated to second order in slow-roll parameters for three closely-related models of inflation, all of which contain a scalar field non-minimally coupled to the Ricci curvature scalar. In most cases, ns may be written as a function of the nonminimal curvature coupling strength ξ alone, with ns(ξ) ≤ 1, although the constraints on ξ differ greatly between ‘new in...

Remotely sensed estimates of crop residue cover (fR) are required to assess the extent of conservation tillage over large areas; the impact of decay processes on estimates of residue cover is unknown. Changes in wheat straw composition and spectral reflectance were measured during the decay process and their impact on estimates of fR were assessed. Proportions of cellulose and hemicellulose dec...

Spectral measurements are employed in many precision agriculture applications, due to their ability to monitor the vegetation's health state. Spectral vegetation indices are one of the main techniques currently used in remote sensing activities, since they are related to biophysical and biochemical crop variables. Moreover, they have been evaluated in some studies as potentially beneficial for ...