A number of investigators have recently claimed, based on both analysis from transport theory and transport-theory-based Monte Carlo calculations, that the diffusion coefficient for photon migration should be taken to be independent of absorption. We show that these analyses are flawed and that the correct way of extracting diffusion theory from transport theory gives an absorption-dependent di...

PURPOSE To characterize the diffusion coefficient of human blood for accurate results in intravoxel incoherent motion imaging. METHODS Diffusion-weighted MRI of blood samples from 10 healthy volunteers was acquired with a single-shot echo-planar-imaging sequence at body temperature. Effects of gradient profile (monopolar or flow-compensated), diffusion time (40-100 ms), and echo time (60-200 ...

This issue of Journal of Medical Radiation Sciences includes a study (Rundle-Thiele et al.) that investigates the correlation between magnetic resonance imaging (MRI)-based estimates of water mobility in glioblastoma tumours and expression of the prognostically important gene promoter methylguanine methyltransferase (MGMT). The authors address previous inconsistent reports regarding a correlati...

The diffusion coefficient of crystalline trypsin in 0.5 saturated magnesium sulfate at 5 degrees C. is 0.020 +/-0.001 cm.(2) per day, corresponding to a molecular radius of 2.6 x 10(-7) cm. The rate of diffusion of the proteolytic activity is the same as that of the protein nitrogen, indicating that these two properties are held together in chemical combination and not in the form of an adsorpt...

Transport and diffusion of particles on modulated surfaces is a nonequilibrium problem which is receiving a great deal of attention due to its technological applications, but analytical calculations are scarce. In earlier work, we developed a perturbative approach to begin to provide an analytic platform for predictions about particle trajectories over such surfaces. In some temperature and for...

Apparent diffusion coefficient (ADC) measurement in diffusion-weighted imaging (DWI) has been reported to be a helpful biomarker for detection and characterization of lesion. In view of the importance of ADC measurement reproducibility, the aim of this study was to probe the variability of the healthy hepatic ADC values measured at 3 MR scanners from different vendors and with different field s...

In this work, the Z-average, effective, apparent diffusion coefficients and their poly-dispersity indexes were investigated for dilute poly-disperse homogeneous spherical particles in dispersion where the Rayleigh-Gans-Debye approximation is valid. The results reveal that the values of the apparent and effective diffusion coefficients at a scattering angle investigated are consistent and the di...

We study the stochastic motion of a Brownian particle driven by a constant force over a static periodic potential. We show that both the effective diffusion and the effective drag coefficient are mathematically well-defined and we derive analytic expressions for these two quantities. We then investigate the asymptotic behaviors of the effective diffusion and the effective drag coefficient, resp...

sorption of flavor compounds to inner layer of polymer packages and subsequent diffusion results in loss of food flavor and consequently decreases shelf life and consumer acceptance of food stuffs which in turn causes major economic losses, so it is of utmost importance to research on diffusivity of these compounds in polymers to minimize negative effects of this phenomenon. in current research...