BACKGROUND Previous diffusion tensor imaging (DTI) studies in patients with obsessive-compulsive disorder (OCD) have reported inconsistent findings, and it is not known whether observed findings are related to abnormalities in axonal structure or myelination. METHODS In this DTI study, we investigated fractional anisotropy, as well as axial and radial diffusivity, in 21 patients with OCD and ...

We study two dimensional Brownian motion in an ordered periodic system of linear reflecting barriers using the sampling method and conformal transformations. We calculate the effective diffusivity for the Brownian particle. When the periods are fixed but the length of the barrier goes to zero, the effective diffusivity in the direction perpendicular to the barriers differs from the standard one...

BACKGROUND AND PURPOSE With the aim of facilitating the early detection of Alzheimer's disease, the Alzheimer's Disease Neuroimaging Initiative proposed two stages based on the memory performance: early mild cognitive impairment (EMCI) and late mild cognitive impairment (LMCI). The current study was designed to investigate structural differences in terms of surface atrophy and microstructural c...

OBJECTIVE Diffusion tensor imaging (DTI) quantifies Brownian motion of water within tissue. Inflammation leads to tissue injury, resulting in increased diffusivity and decreased directionality. We hypothesize that DTI can quantify the damage within acute multiple sclerosis (MS) white matter lesions to predict gadolinium (Gd)-enhancing lesions that will persist 12 months later as T1 hypointensit...

[1] The currently available theoretical and observational evidence for a latitudinal structure of thermocline vertical diffusivity is synthesized and included in a state of the art coupled climate model. Compared to the standard background value of 0.1 cm s , the simulations with the latitudinal structure show only little change in the meridional overturning circulation or northward heat transp...

In this research the drying of four kinds of vegetables was investigated in a vacuum dryer. The effect of temperature on drying rate of samples at various temperatures (30, 35 and 45 °C) was studied. Six thin-layer drying models were fitted to drying data and suitable model was selected from them. Then effective moisture diffusivity and ...

Abstract--A procedure is presented to determine the moisture diffusivity for drying from measured moisture concentratio~a profiles. From error analysis it is shown that the applied space grid for scanning and the one-dimensional resolution of the NMR (nuclear magnetic resonance) method used for the measurements had a minor influence on the accuracy of the determination of the moisture diffusivi...

the produced liquid water in cathode catalyst layer (ccl) has significant effect on the operation of proton exchange membrane fuel cell (pemfc). to investigate this effect, the transport of oxygen in ccl in the presence of immiscible liquid water is studied applying a two-dimensional pore scale model. the ccl was reconstructed as an agglomerated system. to explore the wettability effects, diffe...

diffusivity equation commonly used for pressure distribution prediction in porous media results from substituting equation of state and continuity equation in navier-stokes momentum equation. from mathematical point of view this equation format shows infinite propagation speed for pressure pulse through porous media, which is physically impossible. this issue may caused by numerous assumptions ...

Particles moving along curved trajectories will diffuse if the curvature fluctuates sufficiently in either magnitude or orientation. We consider particles moving at a constant speed with either a fixed or a Gaussian distributed magnitude of curvature. At small speeds the diffusivity is independent of the speed. At larger particle speeds, the diffusivity depends on the speed through a novel expo...