Search results for "doppler"

Farbcodierte Dopplersonographie (FD-Sonographie) primärer und sekundärer Lebertumoren

2008

50 Patients with 78 focal liver lesions were examined via colour-coded Doppler system to study the vascularity of metastatic lesions and primary benign and malignant liver tumours. According to the amount of detectable colour Doppler signals, tumour vascularity was graded into 4 types. Metastases (n = 40) and cavernous haemangiomas (n = 12) seemed to be avascular with no evidence of increased vascularity (Type I/II). Conversely primary liver cancer (PLCA) (n = 7) and focal nodular hyperplasia (FNH) (n = 16) mainly produced arterial Doppler signals within the tumour (Type III/IV). AV shunts and partial portal vein thrombosis could be demonstrated in PLCA. Doppler colour flow imaging for dete…

Quantitative Topography of the Hemodynamic-Oxidative Metabolic Interrelation by Multispot Measurement Approach in Rat Ischemia Models

2001

We applied the multispot measurement approach for both laser Doppler (LD) and a microspectrophotometric method to measure local cerebral blood flow (1CBF) and local tissue hemoglobin oxygenation (IHbO2). We demonstrated that the current technology permits in vivo observation, allowing us to establish a close topographical relation between CBF and HbO2. We measured 1CBF by LD flowmetry and tissue HbO2 by a microspectrophotometric method at multiple corresponding locations using a “scanning” technique that employs a computer-controlled micromanipulator. CBF and HbO2 data from predefined locations were correlated to the topographical situation and then arranged in a three-dimensional (3D) imag…

Monitoring of cortical blood flow: Clinical relevance of experimental laser Doppler studies

1996

Continuous monitoring of cortical blood flow provides real time information of CBF-changes during neurosurgical operations and on the neurointensive care unit. Laser Doppler flowmetry is a continuous, noninvasive technique suitable for measurement of the cortical microcirculation. In a number of experimental studies we have analyzed the characteristics of this method for cortical blood flow monitoring. The high spatial resolution of laser Doppler flowmetry and the heterogeneity of the cortical microvascular network results in a scatter of flow values over a wide range depending on the site of measurement. Data collection from different spots and calculation of frequency histogram may serve …

What is the relationship between chronic cerebrospinal venous insufficiency and multiple sclerosis?

2013

Abstract Although most of the research on multiple sclerosis was focused on its autoimmune aspects, researchers were also considering the roles of other factors, including vascular background of the disease. The idea that multiple sclerosis might be caused by stenoses of the veins draining the brain and spinal cord (the so-called chronic cerebrospinal venous insufficiency), is currently hotly debated by scientific community. Despite conflicting reports, chronic cerebrospinal venous insufficiency seems to be a real clinical phenomenon. However, it remains uncertain how it should be defined and which tests should be used for its detection. Probably this vascular abnormality should be primaril…

Consensus document on intermittent claudication from the Central European Vascular Forum 1st edition - Abano Terme (Italy) - May 2005 2nd revision - …

2008

Discovery of 105 Hz coherent pulsations in the ultracompact binary IGR J16597-3704

2018

We report the discovery of X-ray pulsations at 105.2 Hz (9.5 ms) from the transient X-ray binary IGR J16597-3704 using NuSTAR and Swift. The source was discovered by INTEGRAL in the globular cluster NGC 6256 at a distance of 9.1 kpc. The X-ray pulsations show a clear Doppler modulation implying an orbital period of ~46 minutes and a projected semi-major axis of ~5 lt-ms, which makes IGR J16597-3704 an ultra-compact X-ray binary system. We estimated a minimum companion mass of 0.0065 solar masses, assuming a neutron star mass of 1.4 solar masses, and an inclination angle of <75 degrees (suggested by the absence of eclipses or dips in its light-curve). The broad-band energy spectrum of the…

An XMM-Newton and INTEGRAL view on the hard state of EXO 1745-248 during its 2015 outburst

2017

CONTEXT - Transient low-mass X-ray binaries (LMXBs) often show outbursts lasting typically a few-weeks and characterized by a high X-ray luminosity ($L_{x} \approx 10^{36}-10^{38}$ erg/sec), while for most of the time they are found in X-ray quiescence ($L_X\approx10^{31} -10^{33}$ erg/sec). EXO 1745-248 is one of them. AIMS - The broad-band coverage, and the sensitivity of instrument on board of {\xmm} and {\igr}, offers the opportunity to characterize the hard X-ray spectrum during {\exo} outburst. METHODS - In this paper we report on quasi-simultaneous {\xmm} and {\igr} observations of the X-ray transient {\exo} located in the globular cluster Terzan 5, performed ten days after the begin…

Intraluminal Doppler-sonography: a new device for data analysis and its in vitro test

2002

Summary form only given. A special data acquisition unit has been developed which allows to process on-line not only the mean-phasic Doppler shift signal but also to analyze the spectral contents and the received A-mode signal. The probe consists of a 3f-catheter which is activated by a pulsed transmitter-receiver (Millar). The carrier frequency is 20 MHz and the impulse repetition rate is 62.5 kHz. Two modular A/D converters are used. One digitizes directly the Doppler shift frequencies in the range less than 20 kHz (sampling rate 100 kHz, resolution 12 bit); the other digitizes the RF-signal (sampling rate 200 MHz, resolution 8 bit). For further processing, data are transferred via separa…

Collapse and revival of a Dicke-type coherent narrowing in potassium vapor confined in a nanometric-thin cell

2015

A nanometer-thin-cell (in the direction of laser beam propagation) has been elaborated with the thickness of the atomic vapor column varying smoothly in the range of $L = \unit[50-1500]{nm}$. The cell allows one to study the behavior of the resonance absorption over the $D_1$ line of potassium atoms by varying the laser intensity and the cell thickness from $L = \lambda / 2$ to $L = 2 \lambda$ with the step $\lambda/2$ ($\lambda =\unit[770]{nm}$ is the resonant wavelength of the laser). It is shown that despite the huge Doppler broadening ($>\unit[0.9]{GHz}$ at the cell temperature $\unit[170]{^{\circ}C}$), at low laser intensities a narrowing of the resonance absorption spectrum is observe…

Polarization shaping for unidirectional rotational motion of molecules.

2015

Control of the orientation of the angular momentum of linear molecules is demonstrated by means of laser polarization shaping. For this purpose, we combine two orthogonally polarized and partially time-overlapped femtosecond laser pulses so as to produce a spinning linear polarization which in turn induces unidirectional rotation of N2 molecules. The evolution of the rotational response is probed by a third laser beam that can be either linearly or circularly polarized. The physical observable is the frequency shift imparted to the probe beam as a manifestation of the angular Doppler effect. Our experimental results are confirmed by theoretical computations, which allow one to gain a deep p…