In this paper, we are interested in the finite volume approximation of a system describing miscible displacement in porous media. This system is made of two coupled equations: an anisotropic diffusion equation on the pressure and a convection-diffusion-dispersion equation on the concentration of invading fluid. The anisotropic diffusion operators in both equations require a special care while d...

The determination of the activation volume of diffusion is one of the best methods for the in­ vestigation of the relaxation of atoms or ions around defects. This paper discusses two experimental techniques for the determination of the activation volume for diffusion, by studying the effect of hydrostatic pressure on tracer diffusion and on ionic conductivity. Such experiments require a very cl...

Diffusion tensor imaging provides the ability to study white matter connectivity and integrity noninvasively. The information contained in the diffusion tensors is very complex. Therefore a simple way of dealing with tensors is to compute rotationally invariant scalar quantities. These scalar indices have been used to perform population studies between controls and patients with neurological an...

To determine the diagnostic performance of DWI volume-try for the assessment of complete response after CRT in patients with locally advanced rectal cancer and to compare with volumetry on standard T2-weight MRI, by means of volumetric signal intensity measurements.

ÐDiffusion-weighted magnetic resonance imaging is a relatively new modality capable of elucidating the fibrous structure of certain types of tissue, such as the white matter within the brain. One tool for interpreting this data is volume rendering because it permits the visualization of three dimensional structure without a prior segmentation process. In order to use volume rendering, however, ...

Lateral diffusion of lipids in biological membranes may be influenced by polypeptides, proteins, and other nonlipid membrane constituents. Using concepts from scaled-particle theory, we extend the free-volume model for lipid diffusion to membranes having an arbitrarily large number of components. This theory clarifies the interpretation of the free-volume theory, better reproduces the free-area...

The degree of diffusion tensor anisotropy is often associated with the organization of structural tissues such as white matter. Numerous measures of diffusion anisotropy have been proposed, which could lead to confusion in interpreting and comparing results from different studies. In this study, a new method for representing the diffusion tensor shape, called the three-phase (3P) plot, is descr...

In order to evaluate the sintering behavior of lithium meta titanate (Li2TiO3) powder, the shrinkage of powder compact was measured under constant rates of heating. Densification curves for Li2TiO3 have been constructed with the help of shrinkage powder measured at different heating rates. The activation energy at the initial stage of sintering was determined by analyzing the densification curv...

IMPORTANCE With the increasing use of antiangiogenic agents in the treatment of high-grade gliomas, we are becoming increasingly aware of distinctive imaging findings seen in a subset of patients treated with these agents. Of particular interest is the development of regions of marked and persistent restricted diffusion. We describe a case with histopathologic validation, confirming that this r...

BACKGROUND AND PURPOSE Diffusion-weighted MRI (DWI) demonstrates ischemic tissue with high sensitivity. Although low cerebral blood volume (CBV) is also used as a marker for infarction, the quantitative relationship between diffusion abnormalities and CBV is unknown. We tested the hypothesis that CBV would decrease proportionally to the apparent diffusion coefficient in patients with acute stro...