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At least 19 recordsLinked to original sources
PubMed2005

[The effect of Doppler effect on ultraviolet absorption spectrum from difference in temperature (UVASDT)].

In this paper, the formation of UV absorption spectrum from difference in temperature (UVASDT) is discussed. Broadening of spectral lines might be one of the reasons for the formation of UVASDT. The effect of temperature on the broadening of spectral lines is analyzed. The Doppler SDT function is deduced, and the SDT of C60 and progesterone can be explained by it. It is indicated that the Doppler effect might be the primary reason for the formation of UVASDT of this kind of substance.

Algorithms↗
PubMed2002

Observation of a motional Stark effect to determine the second-order Doppler effect.

The high resolution two-photon spectroscopy of hydrogen is often limited by the second-order Doppler effect. To determine this effect, we apply a magnetic field perpendicular to the atomic beam. This field induces a quadratic motional Stark shift proportional, as the second-order Doppler effect, to v(2) (v atomic velocity). For some magnetic field, these two effects are opposite and the total shift due to the atomic velocity is reduced. We present the first observation of this effect for the 1S-3S transition in hydrogen.

Journal Article↗
PubMed1988

[Doppler effect in cardiology. Continuous Doppler, pulsed Doppler, Doppler color].

Echocardiography has contributed to the exploration of the heart by providing much information, and it has even given rise to new semiological concepts. However, abnormalities of intracardial blood flow, notably shunts and regurgitations, could only be diagnosed indirectly from their effects on cardiac cavities. A new step forward was the advent of pulsed and continuous doppler ultrasound, since from that moment it has been possible to demonstrate abnormal blood flows, to measure their velocity and to determine, albeit with some reservation, such crucial values as pressure gradients. Yet even when these two techniques were combined in the doppler-echotomography systems blind areas persisted, and a blood flow of strongly abnormal direction could in fact escape doppler velocimetry. This is where another development came to the rescue, for it enabled both normal and abnormal flows to be visualized in colours. Owing to this visualization, and provided all possible projections are used, it has become exceptional to "miss" an abnormal blood flow. The diagnosis is now easier and more accurate, and in a second stage the flow can be quantified by pulsed or continuous doppler ultrasound. The colour-coded doppler technique therefore has not superseded the previous one: one may say that it has merely increased diagnostic reliability, but is this not a decisive improvement?

Cardiology↗
PubMed2006

Anomalous Doppler effects in phononic band gaps.

Doppler effects in periodic acoustic media were studied theoretically and experimentally. Analytical formulas are derived using the Green's function formalism. We found that a far field observer cannot hear the sound inside a band gap from a stationary source, but a moving source can be heard even if the frequency is inside the gap, and the Doppler shifts can be inverted or anomalously large.

Journal Article↗
PubMed1975

[Use of the Doppler effect in pathology and vascular surgery of the lower extremities].

A clinical, arteriographic and hemodynamic comparative study, using the Doppler effect in 100 cases, suggests: -- that a study of the Doppler effect is a very useful method of diagnosis to determine the site of obstruction and the state of the blood vessels beyond the obstruction, even in the absence of adequate radiological images; -- following operation, it permits one to assess a case of thrombosis, even when the latter is not obvious clinically. It makes unnecessary post-operative arteriographic controls in tired or high-risk patients.

Angiography↗
PubMed2005

[Doppler effect on width of characteristic line in plasma induced by pulsed laser ablating Al].

Aluminum (Al) plasma was induced with a pulsed Nd: YAG laser beam ablating Al target in Ar. Time-resolved information of the plasma radiation was taken with time-resolved technique, and the spectra of the radiation were recorded with an optical multi-path analyzer (OMA III ), whereupon, time-resolved spectra of the plasma radiation induced by pulsed laser were acquired. Based on the experiment data, Al resonant double lines, Al I 396.15 nm, Al I 394.40 nm, were respectively fitted with Lorentz, Gauss and their linear integrated function (abbr. Integrated function), whereupon, Lorentz and Gauss elements were separated from the experiment data profile curve. By contrasting Lorentz with Gauss curve separated, it was found that the experiment curve mainly consisted of Lorentz element, a with little Gauss. By contrasting Lorentz with Integrated fitting curve for experiment data, a visual picture of the characteristic lines broadened by Doppler effect was exhibited. According to the visual picture, the increase of full half-high width of the characteristic line broadened by Doppler effect was estimated. It was about 2 x 10(-)3 -8 x 10(-3) nm, approximating the theoretical value 6.7 x 10(-)3 nm. As a result, Doppler effect on the width of characteristic lines in the plasma could be reasonably explained by curve fitting analysis and theoretical calculation.

Algorithms↗
PubMed1994

CAE software for the noninvasive diagnosis method on the atherosclerosis by ultrasonic Doppler effect.

Previously, we developed the noninvasive estimation method on the viscoelastic deterioration of the blood vessel and related materials by using Ultrasonic Doppler Effect Sensor and we presented its theoretical foundation. Furthermore, we applied this method to discriminate the human blood vessels with atherosclerosis from normal blood vessels, as the viscoelastic deterioration under in vitro condition and proposed the algorithm for its diagnosis. In the present paper, we propose the software for personal computer (AORTA) for clinical diagnosis on the atherosclerosis within a few minutes by using Ultrasonic Doppler Effect Sensor based on this algorithm. Using this software, we clinically applied this method to patients with atherosclerosis and normal people. It enables us to discriminate the atherosclerotic blood vessels from those of the normal blood vessel within several minutes. By using this system, it is found that the normal human blood vessel has elastic property. When the blood vessel becomes atherosclerotic, it deteriorates in elasticity and shows the viscoelastic property. This system evaluates noninvasively the viscoelastic property of the blood vessel and the degree of the atherosclerosis.

Arteriosclerosis↗
PubMed1978

[Hemotachymetry by Doppler effect (author's transl)].

Transcutaneous hemotachymetry by ultrasonic Doppler effect is a simple, rapid, atraumatic and inexpensive method for obtaining hemodynamic data from cervical arteries; it is immensely useful for diagnosis of circulatory disorders. The author consider the physical principles of the method, its advantages and its drawbacks. Reproducibility and normal hemodynamic values are discussed.

Blood Flow Velocity↗
PubMed1994

Algorithm of the noninvasive diagnosis method on the atherosclerosis by ultrasonic Doppler effect.

Previously we proposed Acoustical Imaging and Processing Method to measure the viscoelastic property of the blood vessels of a canine and the related materials using Ultrasonic Doppler Effect Measurement. Furthermore, its theoretical foundation was presented. In this paper, this method is applied to measure the viscoelastic mechanical property, that is, the mechanical degradation of human blood vessels by a percutaneous noninvasive method. Based on these results, we proposed the algorithm of the noninvasive estimation method on the viscoelastic mechanical property of the blood vessel by using Doppler Effect Sensor. This method makes it possible to discriminate the blood vessel with arteriosclerosis from a normal blood vessel. Clinical applications were successfully performed using our developed computer software based on our proposed algorithm.

Algorithms↗
PubMed2003

The Doppler effect in NMR spectroscopy.

An NMR sample may be subject to motions, such as those due to sample spinning or to liquid flow. Is the spectrum of such a sample affected by the Doppler effect? The question arises because, instrumental dimensions being much shorter than the wavelength, it is the near-field of the precessing magnetic moment which couples to the receiver coil, rather than the radiated far-field. We expand the near-field into plane propagating waves. For each such wave there is another one with the same amplitude, propagating in the opposite direction. The Doppler shifts are therefore equal and opposite. In the model case of a small fluid sample moving with constant velocity, this leads to a distribution of Doppler shifts which is symmetrical with respect to the unshifted frequency: there is no net spectral shift. We examine the possibility of observing the Doppler distribution in this case. We also consider the case of thermal motion of a gas. We draw attention to the resolved Doppler splitting of molecular rotational transitions in a supersonic burst as observed in a microwave resonator. We also mention briefly the Doppler effect in molecular beam spectroscopy.

Journal Article↗
PubMed1999

New blind mobility aid devices based on the ultrasonic Doppler effect.

An original approach to electronic blind mobility aid combined with ultrasonic wave processing and spatial hearing has allowed the design of new blind mobility aid devices. These devices convert inaudible ultrasound echoes into audible sound via the Doppler effect, preserving even slight modification of the high frequency wave, so as to provide the user with higher acuity information regarding his movement, as well as object movement and their spatial location.

Activities of Daily Living↗
PubMed1982

Intensity changes in the Doppler effect.

When a source moves in any direction, the source strength and the frequencies are altered by the Doppler effect. It is shown that the source strength divided by the cube of the frequency is a Lorentz invariant.

Journal Article↗
PubMed1980

[Echocardiographic study with the Doppler effect, of floating of the interventricular septum as a determining factor in the genesis of innocent murmurs].

The present study offers the possibility of individuating the genesis of innocent murmurs. 30 patients between 5 and 20 years, showing at the phonocardiogram a train of oscillations in a proto-mesosistolic or mesosistolic phase with characteristics that testify an innocent murmur, have been examined. The routine examinations and cardiac cateterism to exclude congenital or acquired heart diseases have been done to all the patients. The echocardiographic examination has shown a characteristic floating of the interventricular septum, that, producing a variable mutability of the dimensions of the right ventricular cavities, determines, particularly in the tract of the right ventriculae efflux, a hematic turbolent flow well visible with the Doppler effect. The genesis of the innocent murmurs must be referred to such a turbolence, secondary to the floating of the septum, and this accords with Feruglio, who asserts he has always found, with the endocavitary phonocardiography, innocent murmurs only in the infundibulum of the pulmonary.

Doppler Effect↗
PubMed2003

Doppler effect in resonant photoemission from SF6: correlation between Doppler profile and Auger emission anisotropy.

Fragmentation of the SF6 molecule upon F 1s excitation has been studied by resonant photoemission. The F atomiclike Auger line exhibits the characteristic Doppler profile that depends on the direction of the photoelectron momentum relative to the polarization vector of the radiation as well as on the photon energy. The measured Doppler profiles are analyzed by the model simulation that takes account of the anisotropy of the Auger emission in the molecular frame. The Auger anisotropy extracted from the data decreases with an increase in the F-SF5 internuclear distance.

Journal Article↗