Propagation of high-frequency radiation in an anisotropic medium can be described in terms of two normal modes with different polarizations and different absorption coefficients. We investigate the properties of the normal modes in a strongly magnetized hydrogen gas for conditions expected in atmospheres of isolated neutron stars. We use the Kramers-Kronig relations to obtain the polarizability...

We describe the results of a survey of the UV absorption properties of the Boroson & Green sample of AGN, which extends from the Seyfert (MV ≃ −21) to the luminous quasar (MV ≃ −27) level. The survey is based mostly on HST archival data available for > ∼ 1/2 of the 87 sample objects. Our main result is that soft X-ray weak quasars (SXWQs, 10 AGN with αox ≤ −2) show the strongest UV absorption a...

Radio-frequency (RF) electromagnetic fields are readily absorbed in biological matter and lead to dielectric heating. To understand how RF radiation interacts with macromolecular structures and possibly influences biological function, a quantitative description of dielectric absorption and heating at nanometer resolution beyond the usual effective medium approach is crucial. We report an exempl...

Atmosphere scatters and absorbs incident solar radiation modifying its spectral content and decreasing its intensity at the surface. It is very useful to classify the earth-atmospheric solar radiation into several components direct solar surface irradiance (Edirect), diffuse-sky downward surface irradiance (Ediffuse), total surface irradiance, and upwelling flux at the surface and at the topof-...

This paper reviews the research in nanomaterials conducted in our laboratory in the last decade using conventional and synchrotron radiation techniques. While preparative and conventional characterisation techniques are described, emphasis is placed on the analysis of nanomaterials using synchrotron radiation. Materials of primary interests are metal nanoparticles and semiconductor nanowires an...

We demonstrate a laboratory method for imaging small blood vessels using x-ray propagation-based phase-contrast imaging and carbon dioxide (CO(2)) gas as a contrast agent. The limited radiation dose in combination with CO(2) being clinically acceptable makes the method promising for small-diameter vascular visualization. We investigate the possibilities and limitations of the method for small-a...

The relative population of the fine structure sublevels of an atom’s ground state is affected by radiative transitions induced by an anisotropic radiation flux. This causes the alignment of atomic angular momentum. In terms of observational consequences for the interstellar and intergalactic medium, this results in the polarization of the absorption lines. In the paper we consider the condition...

In this work, photostability, absorption and emission intensity of coated polycarbonate (PC) sheets with optical brightener (OB) as a wavelength converter material have been investigated. In addition, this coated sheet was used as a wall for microalgae culture flask, as a small scale photobioreactor, for studying the spectral conversion of UV-A radiation to blue light region and its effect ...

Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein ...