Doppler signal detection

Qiu, H.-H., Sommerfeld, M. and Durst, F., Two novel Doppler signal detection methods for laser-Doppler and phase-Doppler anemometry. Meas. Sci. Techn., 5, 769-778 (1994)... 

Markus HS, Droste DW, Kaps M, Larrue V, Lees KR, Siebler M, Ringelstein EB. Dual antiplatelet therapy with clopidogrel and aspirin in s3miptomatic carotid stenosis evaluated using doppler embolic signal detection the Clopidogrel and Aspirin for Reduction of Emboli in Symptomatic Carotid Stenosis (CARESS) trial. Circulation 2005 lll(17) 2233-2240. 

MacKinnon AD, Aaslid R, Markus HS (2005). Ambulatory transcranial Doppler cerebral embolic signal detection in symptomatic and asymptomatic carotid stenosis. Stroke 36 1726-1730... 

Ibrahim, K. and Bachalo, W., The significance of the Fourier Analysis in Signal Detection and Processing in Laser Doppler and Phase Doppler Applications. Proc. of the 6th Int. Symp. on Appl. of Laser Techn. to Fluid Mechanics, Lisbon, Portugal, paper 21.5 (1992)... 

In some cases color/power Doppler examinations do not show the characteristic spoke-wheel pattern but vessels randomly distributed in the lesion and at its periphery, without a clear central artery. In these lesions, the detection of an arterial Doppler signal with high diastolic flow can help in differentiating FNH from malignant lesions, such as hypervascular metastases and HCCs. 

Elastic scattering is also the basis for Hdar, in which a laser pulse is propagated into a telescope s field of view, and the return signal is collected for detection and in some cases spectral analysis (14,196). The azimuth and elevation of the scatterers (from the orientation of the telescope), their column density (from the intensity), range (from the temporal delay), and velocity (from Doppler shifts) can be deterrnined. Such accurate, rapid three-dimensional spatial information about target species is useful in monitoring air mass movements and plume transport, and for tracking aerosols and pollutants (197). 

The relationship between LAA and early recurrence is likely to be largely mediated by arterial embolism from atherosclerotic plaque, although recurrent low-flow stroke may also occur due to severe vessel stenosis or occlusion. In recently symptomatic individuals with moderate-or-severe ICA stenosis, platelet-fibrin embolic signals (ES) are commonly detected in the MCA using transcranial Doppler (TCD) ultrasound and have been reported to independently predict a fivefold increase in 90-day recurrence. " ... 

Doppler velocity may provide a Mossbauer spectrum with a large increase in the signal to noise ratio compared to that obtained in the transmission mode. The type of radiation used to generate the scattered Mossbauer spectrum depends on the internal conversion coefficient a a large value of a, which favors the emission of X rays by the Mdssbauer isotope, makes X-ray detection appropriate, while a small value of a favors y-ray detection. 

The data recorded as the laser frequency is scanned consists of the fluorscence signal from the PMT, a Doppler-free I2 spectrum and frequency markers from the etalon. The etalon provides a calibration of the frequency scan. The Doppler-free I2 spectra provides an absolute frequency reference used to correct for small laser frequency drifts, separator voltage drifts and to determine the absolute acceleration voltage of the separator for the Doppler shift corrections. We are thus able to record data over long periods of time, e.g. 3 hours, and maintain a reasonable resolution of 100 MHz. Some of the first online data recorded with this system is shown in Figure 2. The overall detection efficiency has been measured to be 1/1000, i.e. one detected photon per 1000 atoms, for the largest transition in the nuclear spin 1/2 isotopes. 

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