The interpretation of Fourier spectra in the time domain is critically examined. Power density spectra defined and calculated in the time domain are compared with Fourier spectra in the frequency domain for three different types of variability: periodic signals, Markov processes and random shots. The power density spectra for a sample of neutron stars and black hole binaries are analyzed in bot...

A polarization propagator for x-ray spectra is outlined and implemented in density functional theory. It rests on a formulation of a resonant-convergent first-order polarization propagator approach which makes it possible to directly calculate the x-ray absorption cross section at a particular frequency without explicitly addressing the excited states. The quality of the predicted x-ray spectru...

In this study, we aimed to measure the directly ionizing component (muons and photons) and the indirectly ionizing component (neutrons) of the cosmic-ray spectra and evaluate their dose rate contribution to the total dose rate on a ground level in Japan. Measurements were carried out in Tohoku University, Japan, from October 2000. The pulse-height spectra of the cosmic-ray photons and muons wer...

I review the main theoretical conclusions from high-energy spectral observations of Galactic Black Hole Candidate systems. With an eye towards future missions, I show how the ability to reach such conclusions depends critically on the type of spectral coverage one has available. Perhaps the most important factor in determining how well a set of observations constrains theoretical models is the ...

Past X-ray observations by ASCA suggest that warm absorbers (Ovii and Oviii edges) are apparently rare in high luminosity AGNs (quasars) while they are more common in low luminosity AGNs (Seyferts). However, this could be a selection effect if high luminosity AGNs have mostly narrow absorption lines (with no strong bound free edges), which escaped detection by the low resolution of ASCA. To che...

We have used data from the Cosmic Ray Subsystem on the Voyager spacecraft to measure the spectra of He, C, N, 0, and Ne with 4-124 MeV per nucleon (for 0) during solar minimum conditions near the end of 1977. By subtracting both a low-energy interplanetary component and the high-energy galactic component we have determined the energy spectra of the "anomalous" cosmic-ray species He, N, 0, and N...

The character of the electronic transitions in the ultraviolet-visible-near infrared (UV-vis-NIR) spectra of platinum-bis(alkynyl) bridged, bis-triarylamine mixed-valence systems trans-[Pt(C≡CC6H4NAr2)2 (PR3)2](n+) (R = ethyl, Ar = C6H4CH3-4 (1) or C6H4OCH3-4 (2); R = Ph, Ar = C6H4CH3-4 (3) or C6H4OCH3-4 (4), n = 0, 1, 2) has been determined from a combination of spectroscopic measurement and d...

Strong characteristic Kα X-ray lines are accompanied by weak lines due to the radiative Auger effect (RAE) [1, 2]. The characteristic Kα fluorescent X-rays (K-L2,3 lines) are emitted by the 2p→1s electric dipole transition after one of the 1s electron photoionization, Though the probability is less than 0.01, one of the 2p electrons is excited into an unoccupied discrete or continuum level simu...

Introduction Superficial X-ray therapy is one of the most important treatment methods in radiotherapy especially in the treatment of superficial skin lesions (Up to 300 kVp). Quality of the X-ray beam that can be expressed by Half-Value Layer (HVL), are important indices for this type of treatment effective energy of photon and Homogeneity Coefficient (HC). Materials and Methods The HC of the s...

Radiative Auger spectra are weak X-ray emission spectra near the characteristic X-ray lines. Radiative Auger process is an intrinsic energy-loss process in an atom when a characteristic X-ray photon is emitted, due to an atomic many-body effect. The energy loss spectra correspond to the unoccupied conduction band structure of materials. Therefore the radiative Auger effect is an alternative too...