Search results for "Spatial expansion"
showing 2 items of 2 documents
Preliminary experience with the application of Gadolinium-DTPA before MR imaging-guided laser-induced interstitial thermotherapy of brain tumors
1997
The purpose of this study was to investigate the potential value of i.v. gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) applied before MRI-guided laser-induced interstitial thermotherapy (LITT) of brain tumors without original enhancement, especially in defining total lesion size during therapy. MRI-guided LITT was performed on two patients with astrocytoma WHO II. For both patients, Gd-DTPA was administered intravenously after a first irradiation period and LITT was continued after pulling back the light guide to coagulate the upper parts of the tumor. In both patients, the whole irreversible damaged zone of the second irradiation period after Gd-DTPA showed an intense increase …
A method to transform a nonlocal model into a gradient one within elasticity and plasticity
2014
Abstract A method based on the principle of the virtual power (PVP) is presented, by which a mechanical problem of nonlocal elasticity, or plasticity, is transformed into one of gradient nature. Different Taylor series expansion techniques are applied to the driving local strain fields of the nonlocal problem, either full spatial expansion within the bulk volume, or uni-directional expansion along the normal to the thin boundary layer. This, at the limit when the boundary layer thickness tends to zero, makes the PVP of the nonlocal model transform itself into one featuring a counterpart gradient model. Also, for a class of “associated” nonlocal and gradient elasticity models (i.e. the kerne…