Using forced Rayleigh scattering, the tracer diffusion of methyl red through water and eight other solvents at different temperatures is investigated and the results are compared to the Cohen-Turnbull theory of free-volume diffusion. In seven solvents the effective non-Arrhenius activation energy measured experimentally agrees with the Cohen-Turnbull energy. In water, however, the diffusion can...

We report the case of malignant oligodendroglioma in a 36-year-old man who underwent diffusion-weighted, perfusion-weighted, and volumetric MR imaging before and after PCV (procarbazine, CCNU, vincristine) chemotherapy. The tumor regions exhibiting a low apparent diffusion coefficient and increased relative cerebral blood volume showed a marked response to chemotherapy and dramatic decrease in ...

Abstract. This paper investigates the exit-time for a broad class of symmetric finite-range jump processes via the corresponding master equation, a nonlocal diffusion equation suitably constrained. In direct analogy to the classical diffusion equation with a homogeneous Dirichlet boundary condition, the nonlocal diffusion equation is augmented with a homogeneous volume constraint. The volume-co...

Diffusion parameters of the extracellular space (ECS) are changed in many brain pathologies, disturbing synaptic as well as extrasynaptic "volume" transmission, which is based on the diffusion of neuroactive substances in the ECS. Amyloid deposition, neuronal loss, and disturbed synaptic transmission are considered to be the main causes of Alzheimer's disease dementia. We studied diffusion para...

Soot concentration distribution is investigated both numerically and experimentally in methane-air diffusion flame. The experimental work is conducted with a cylindrical swirl stabilized combustor. Filter paper technique is used to measure soot volume fraction inside the combustor. The numerical simulation is based on the solution of the fully-coupled conservation equations for swirling turbule...

In Diffusion Weighted MR Imaging (DWI), the signal is affected by the biophysical properties of neuronal cells and their relative placement, as well as extra-cellular tissue compartments. Typically, microstructural indices, such as fractional anisotropy (FA) and mean diffusivity (MD), are based on a tensor model that cannot disentangle the influence of these parameters. Recently, Neurite Orient...

APGAR: Activity Pulse Grimace Appearance Respiration; PImax: Maximal Inspiratory Pressure; PEmax: Maximal Expiratory Pressure; DLCO: Diffusion Capacity; β-HCG: Bbeta Human Chorionic Gonadotropin; BMI: Body Mass Index; FVC: Forced Vital Capacity; FEV1: Forced Expiratory Flow at One Second; FEF25-75: Forced Expiratory Flow 25-75; RV: Residual Volume; TLC: Total Lung Capacity; DLCO/VA: Diffusion C...

Macrocerebellum is a rare entity characterized by an enlarged cerebellum. We describe a case of a 48-month-old child with macrocerebellum. We performed serial volumetric analysis [total brain volume (TBV) and cerebellar volume] over a period of 4 years. We analyzed the white matter microstructure in the cerebellum using diffusion tensor imaging (DTI). In our patient, we found higher fractional ...

The signal decay with increasing b-factor at fixed echo time from brain tissue in vivo has been measured using a line scan Stejskal-Tanner spin echo diffusion approach in eight healthy adult volunteers. The use of a 175 ms echo time and maximum gradient strengths of 10 mT/m allowed 64 b-factors to be sampled, ranging from 5 to 6000 s/ mm2, a maximum some three times larger than that typically u...

The primarily intravascular magnetization transfer (MT)-independent changes in functional MRI (fMRI) can be separated from MT-dependent changes. This intravascular component is dominated by an arterial blood volume change (DeltaCBV(a)) term whenever venous contributions are minimized. Stimulation-induced DeltaCBV(a) can therefore be measured by a fit of signal changes to MT ratio. MT-varied fMR...