BACKGROUND Qualitative and quantitative assessment of renal blood flow is valuable in the evaluation of patients with renal and renovascular diseases as well as in patients with heart failure. The temporal pattern of renal flow velocity through the cardiac cycle provides important information about renal haemodynamics. High temporal resolution interleaved spiral phase velocity mapping could pot...

The famous Fizeau’s interferometry experiment with flowing water is commonly cited as a demonstration of the velocity transformation in the special relativity. In this investigation, by taking into account the modification of the propagation velocity due to the motion of dielectric medium and the modification of the propagation length due to the Sagnac effect, an entirely different interpretati...

MRI can measure several important hemodynamic parameters but might not yet have reached its full potential. The most common MRI method for the assessment of flow is phase-contrast MRI velocity mapping that estimates the mean velocity of a voxel. This estimation is precise only when the intravoxel velocity distribution is symmetric. The mean velocity corresponds to the first raw moment of the in...

We examine differences between various zero-group-velocity modes in photonic crystals, including those that arise from Bragg diffraction, anticrossings, and band repulsion. Zero-group velocity occurs at points where the group velocity changes sign, and therefore is conceptually related to “left-handed” media, in which the group velocity is opposite to the phase velocity. We consider this relati...

S printing has previously been described as consisting of a series of phases: an acceleration phase from 0 to 10 m, a transition phase, and then a maximum velocity phase from 36 to 100 m during a 100-m sprint (7). Mero et al. (34) described the acceleration phase as being in the first 30–50 m, followed by a maximum velocity phase and a phase of deceleration. However, for many sporting activitie...

abstract   background: postural instability has been identified as a potential precursor of falls in elderly subjects. postural stability in quiet stance is commonly assessed with center of pressure (cop) measures. the purpose of this study was to determine testretest reliability and minimal detectable change (mdc) for the center of pressure (cop) measures in the elderly subjects.   methods: ei...

we studied the effect of different concentrations of alpha-tocopherol on in vitro cupric ions induced oxidation of low density lipoproteins (ldl). human native ldl (50 µg protein/ml) oxidation was induced by 10 µmol/l of cuso4. conjugated dienes were measured spectrophotometrically for up to 440 minutes. the length of the lag phase (tlag), maximum velocity of the reaction (vmax) and the maximum...

A sprint kayaking specific deterministic model was used to identify key performance related technique factors using data from 12 international-level kayakers. There was large variability in the strength of the between-factor relationships across the group. The pull phase was split into 3 components with the 1st phase contributing the most to increases in boat velocity and the 3rd phase causing ...

Variations in the phase velocity of earthquake-generated surface waves have been used to determine local variations in the thickness of the earth's crust. It is of interest to determine whether this method can be used to delineate structures encountered by the exploration geophysicist. A seismic model study of the effect of thickness changes, lithology changes, faults-and srnrps, on the phase v...