We have addressed the problem of tracking the nonrigid motion of the heart using a sequence of velocity fields and a sequence of contours. The information from both the contours and the dense velocity fields is integrated into a deforming mesh that is placed over the myocardium at one time frame and then tracked over the entire cardiac cycle. The deformation is guided by a smoothing filter that...

Development of counter-rotating streamwise vortices in a rectangular channel with onesided wavy surface has been experimentally quantified using hot-wire anemometry. The wavy surface has fixed amplitude of 3.75 mm. The counter-rotating vortices are pre-set by means of a sawtooth pattern cut at the leading edge of the wavy surface. Variations of the central streamwise velocity Uc with a channel ...

We introduce a new technique for estimating the optical flow field, starting from image sequences. As suggested by Fleet and Jepson (1990), we track contours of constant phase over time, since these are more robust to variations in lighting conditions and deviations from pure translation than contours of constant amplitude. Our phase-based approach proceeds in three stages. First, the image seq...

In this article, we introduce a new technique for estimating the optical ow eld, starting from image sequences. As suggested by Fleet and Jepson, we track contours of constant phase over time, since these are more robust to variations in lighting conditions and deviations from pure translation than contours of constant amplitude. Our phase-based approach proceeds in three stages. First, the ima...

From our daily experience, it is very clear that relative motion cues can contribute to correctly identifying object boundaries and perceiving depth. Motion-defined contours are not only generated by the motion of objects in a scene but also by the movement of an observer's head and body (motion parallax). However, the neural mechanism involved in detecting these contours is still unknown. To e...

Vocal tract X-ray image sequence are used to study articulatory phenomena and to design approximate articulatory models. The purpose of this paper is to describe an automatic tracking tool for extracting the contours of the tongue which is the most important articulator. According to the tongue part considered, the contour may appear either as an isolated contour, or a contour lying in a region...

There is little direct psychophysical evidence that the visual system contains mechanisms tuned to head-centered velocity when observers make a smooth pursuit eye movement. Much of the evidence is implicit, relying on measurements of bias (e.g., matching and nulling). We therefore measured discrimination contours in a space dimensioned by pursuit target motion and relative motion between target...

At z=0.809, RXJ 1716.6+6708 is the second most distant X-ray selected cluster so far published and the only one with a large number of spectroscopically determined cluster member velocities. The optical morphology of RXJ 1716.6+6708 resembles an inverted S-shape filament with the X-rays coming from the midpoint of the filament. The ROSAT HRI contours have an elongated shape that roughly coincid...

We present a velocity-constrained front propagation approach for myocardium segmentation from magnetic resonance intensity image (MRI) and its matching phase contrast velocity (PCV) images. Our curve evolution criterion is dependent on the prior probability distribution of the myocardial boundary and the conditional boundary probability distribution, which is constructed from the MRI intensity ...

A computational fluid dynamic (CFD) study compared two configurations of distal anastomosis of 12 mm Contegra conduit: conventional 'circular' vs. oblique 'elliptical' anastomosis extended on the left PA, evaluating pressure and velocity profiles, and shear stress, from PA origin to the bifurcation. 'Elliptical' anastomosis provides larger (=54% difference) cross-sectional area than 'circular' ...