Doppler analysis of flow in intracranial arteries is now possible using a 2 MHz probe allowing sufficient penetration of bone to obtain signals noninvasively. Thirty-two normal subjects, and 11 patients with cerebrovascular diseases including vasospasm following subarachnoid hemorrhage, middle cerebral artery stenosis, and extracranial internal carotid artery stenosis were studied by transcrani...

Perfusion measurements using conventional laser Doppler techniques are affected by the variations in tissue optical properties. Differences in absorption and scattering will induce different path lengths and consequently will alter the probability that a Doppler shift will occur. In this study, the fraction of Doppler shifted photons and the Doppler broadening of a dynamic medium, are measured ...

This will be a discussion of the non-invasive determination of the viscosity of a non-Newtonian fluid in laminar pipe flow over the range of shear rates present in the pipe. The procedure used requires knowledge of the flow profile in and the pressure drop along a long straight run of pipe. The profile is determined by using a pulsed ultrasonic Doppler velocimeter. This approach is ideal for ma...

To evaluate the accuracy of a pulsed multigated Doppler system, 128 carotid arteries were examined. The spectral broadening index was calculated from the power spectrum of a small sample volume located in the center of the stream according to the flow profile and was related to the degree of stenosis as determined by contrast angiography. Even minor wall irregularities seen on the angiogram wer...

Recent analyses of the intergalactic UV background by means of the He  Lyα forest assume that He  and H  absorption features have the same line widths. We omit this assumption to investigate possible effects of thermal line broadening on the inferred He /H  ratio η and to explore the potential of intergalactic He  observations to constrain the thermal state of the intergalactic medium...

In this paper we consider the effects of resonance and electron scattering on the escape of Lyman α photons during cosmological hydrogen recombination. We pay particular attention to the influence of atomic recoil, Doppler boosting and Doppler broadening using a Fokker-Planck approximation of the redistribution function describing the scattering of photons on the Lyman α resonance of moving hyd...

We report on the experimental realization of large fractional pulse delays in a hot, Doppler-broadened rubidium vapor. A pump laser burns a deep spectral hole in the inhomogeneously broadened vapor. The delay is shown to be widely tunable by both power broadening the resonance and frequency modulating the pump laser. The simplicity of the scheme opens up the possibility for practical optical de...

The shape and shift of the 535.0 nm thallium line resulting from the photodissociation of thallium iodide perturbed by krypton and xenon were investigated at low densities. The Doppler and collision broadening components of the line shape have been determined. The linear dependence of both the Lorentzian half-width and the shift on the perturbing gas density was found and interpreted in terms o...

Supernova flux and polarization spectra bring vital information on the geometry, physical conditions, and composition structure of the ejected matter. For some supernovae the circumstellar matter is also probed by the observed spectra. Some of this information can be inferred directly from the observed line profiles and fluxes, but because of the Doppler broadening and severe line blending, int...