We consider the X-ray emission due to bremsstrahlung processes from sphericallysymmetric low radiative-efficiency hot accretion flows around supermassive and galactic black holes. We calculate surface brightness profiles and Michelson visibility functions for a range of density profiles, ρ ∼ r−3/2+p, with 0 < p < 1, to allow for the presence of outflows. We find that although the 1 keV emitting...

The duration necessary to detect chromatic stimuli was measured for wavelengths between 463 and 620 nm. Stimuli were presented either in hue substitution (replacement of white by a chromatic stimulus of matched luminance) or as increments. Two observers viewed a 1 degrees 45' homogeneous white field. A trial consisted of replacement of the central 40' of the field by a chromatic stimulus. In su...

the quantitative analysis of cardiac motions in echocardiography images is a noteworthy issue in processing of these images. cardiac motions can be estimated by optical flow (of) computation in different regions of image which is based on the assumption that the intensity of a moving pattern remains constant in consecutive frames. however, in echocardiographic sequences this assumption may be v...

A direct method called fixation is introduced for solving the general motion vision problem, arbitrary motion relative to an arbitrary environment. This method results in a linear constraint equation which explicitly expresses the rotational velocity in terms of the translational velocity. The combination of this constraint equation with the Brightness-Change Constraint Equation solves the gene...

We demonstrate a picosecond source of correlated photon pairs using a micro-structured fibre with zero dispersion around 715 nm wavelength. The fibre is pumped in the normal dispersion regime at ~708 nm and phase matching is satisfied for widely spaced parametric wavelengths. Here we generate up to 10;7 photon pairs per second in the fibre at wavelengths of 587 nm and 897 nm, while on collectin...

We investigate the potential of multi-colour photometry for partial mode identification in both long-and short-period variable subdwarf B stars. The technique presented is based on the fact that the frequency dependence of an oscillation's amplitude and phase bears the signature of the mode's degree index l, among other things. Unknown contributing factors can be eliminated through the evaluati...

The finite angular spectral width of a 2D resonant grating mirror is adjusted to select the fundamental transverse mode of a laser and to filter out higher order modes. The selection principle is explained phenomenologically on a simplified 1D model. The 2D design is made so as to sustain the large field concentration in the grating slab-waveguide mirror, and the technology permitting to obtain...