Eddy diffusion. Medical search. Frequent questions

b) The nominal eddy diffusion coefficient profiles used in our model for the nominal K2-18b and the hotter variant. (astrobiology.com)
normal states and abnormal conditions are easily interpreted through the use of DWI in conjunction with apparent diffusion coefficient (ADC) imaging by correlating findings of hyperintensity on DWI images with findings of hypointensity on ADC images (see the images below). (medscape.com)
On DWI commonly used to diagnose acute stroke (see the image below), diffusion is described by using the apparent diffusion coefficient (ADC). (medscape.com)
MRI sequences such as diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) maps and spectroscopic studies have improved quantitative analysis and provided potential for correlating image findings with medulloblastoma molecular subtypes. (medscape.com)

In my understanding viscosity is closely related to diffusion. (cfd-online.com)
If this argument is denied, then why people always use eddy-viscosity/diffusion concept to simulate turbulence? (cfd-online.com)
I doubt the justification of eddy-viscosity approach on turbulence modeling for I doubt the turbulence is generated by diffusion, and I doubt whether turbulence will definitely/solely behave like momentum diffusion. (cfd-online.com)
Since people first found the logrithmic profile from experiments, and then try to fit it by eddy viscosity. (cfd-online.com)
And, interestingly, people find more and more complicated eddy-viscosity to fit different turbulence structure(like space varying/time varying/discontinuous eddy viscosity functions), which is beyond physical meaning, we are going for mathematical games,not physics! (cfd-online.com)
And the data call for negative/'exotic' diffusivity(page 66, fig5), which means pure diffusivity(for concentration)---eddy viscosity(for momentum of fluid) is a not good candidate for fitting the data! (cfd-online.com)
People also came up with 'Geophysical Turbulence' concept which is of very large scale, and the eddy-viscosity they got is several orders of magnatude away from common 'Turbulence', is Geophysical Turbulence really turbulence? (cfd-online.com)
G.-S. Karamanos and G.E. Karniadakis, A spectral vanishing viscosity method for large-eddy simulations. (esaim-m2an.org)
R.H. Kraichnan, Eddy viscosity in two and three dimensions. (esaim-m2an.org)

These eddies can vary widely in size, from subtropical ocean gyres down to the small Kolmogorov microscales, and occur as a result of turbulence (or turbulent flow). (wikipedia.org)
And does this mean that diffusion is the reason of turbulence? (cfd-online.com)
We are doing parameter recoginition from turbulence and the parameter(eddy viscoty) is has to be so complicated to fit the data! (cfd-online.com)
G.-H. Cottet, D. Jiroveanu and B. Michaux, Vorticity dynamics and turbulence models for Large-Eddy Simulations. (esaim-m2an.org)
M. Lesieur and R. Roggalo, Large-eddy simulations of passive scalar diffusion in isotropic turbulence. (esaim-m2an.org)

Active research is now focused on the contributions of eddy diffusion to both atmospheric and oceanic known processes. (wikipedia.org)
Atmospheric diffusion and air pollution problems = Voprosy atmosfernoy diffuzii i zagryazneniya vozdukha. (epa.gov)

Robertson, PL and Jacobson, D 2011 , 'Knowledge Transfer and Technology Diffusion: an introduction' , in Knowledge Transfer and Technology Diffusion , Edward Elgar Publishing. (edu.au)
A Handbook of Industrial Districts , Edward Elgar Publishing Limited, Cheltenham, pp. 269-280. (edu.au)

Measurement of the self-diffusion tensor of water in the human brain. (mpg.de)
The MDD group ( n = 29) and a healthy control group ( n = 47) underwent diffusion tensor imaging (DTI) scans and an analysis was conducted using TBSS. (cambridge.org)
[ 1 , 2 ] Imaging and interpretation of water diffusion have improved with the development of diffusion tensor imaging (DTI). (medscape.com)
Diffusion tensor imaging has shown strong momentum in research performed to evaluate the neural fibers of the central nervous system (CNS). (medscape.com)
Diffusion tensor imaging can be used to measure anisotropy per voxel and provides directional information relevant for magnetic resonance tractography or fiber tracking in vivo. (medscape.com)
Diffusion tensor imaging allows direct examination of the brain microstructure and has become a useful tool for investigating brain disorders such as stroke, epilepsy, multiple sclerosis (MS), brain tumors, and demyelinating and dysmyelinating disorders. (medscape.com)

In fluid dynamics, eddy diffusion, eddy dispersion, or turbulent diffusion is a process by which fluid substances mix together due to eddy motion. (wikipedia.org)

The problem with turbulent diffusion in the atmosphere and beyond is that there is no single model drawn from fundamental physics that explains all its significant aspects. (wikipedia.org)

According to the gradient transport theory, the diffusion flux at a fixed point in the fluid is proportional to the local concentration gradient. (wikipedia.org)
This is described as the "gradient model" in a later section, the name derived from the fact that diffusion fluxes are proportional to the local gradient in concentration, just as for molecular diffusion. (wikipedia.org)
In this section a mathematical framework based on continuity equation is developed to describe the evolution of concentration profile over time, under action of eddy diffusion. (wikipedia.org)
Velocity and concentration field are decomposed into mean and fluctuating (eddy) components. (wikipedia.org)
It is then derived that the concentration flux due to eddies is given by covariance of fluctuations in velocity and concentration. (wikipedia.org)
On page 63, a interesting point made-----the variation of suspended sediment concentration is in contrast to diffusion models. (cfd-online.com)
We verify the latter calculation by using Fick's own calculated concentration profiles and show that the modern diffusion theory predicts the inverted funnel measurements almost as well as those in the cylindrical tube. (scirp.org)

In this work, we aimed to predict, using linear response theory, the residual 3-D eddy current field required for geometric distortion correction based on phantom eddy current field measurements. (univr.it)
The model's performance was tested on diffusion weighted images of four normal volunteers, following distortion correction, the quality of the Stejskal-Tanner diffusion-weighted images was found to have comparable quality to image registration based corrections (FSL) at low b-values. (univr.it)
An assessment of eddy current sensitivity and correction in single-shot diffusion-weighted imaging. (mpg.de)

In turbulent flows, on top of mixing by molecular diffusion, eddies stir (Eddy diffusion § Note on stirring and mixing) the fluid. (wikipedia.org)
In most macroscopic flows in nature, eddy diffusion is several orders of magnitude stronger than molecular diffusion. (wikipedia.org)
J.-L. Guermond, J.T. Oden and S. Prudhomme, Mathematical perspectives on the Large Eddy Simulation models for turbulent flows. (esaim-m2an.org)
A. Leonard, Energy cascade in Large-Eddy simulations of turbulent fluid flows. (esaim-m2an.org)

The disk diffusion method is a second method of determining antibiotic sensitivity (see image below). (medscape.com)

This phenomenon is called molecular diffusion, and its mathematical aspect is captured by the diffusion equation. (wikipedia.org)

They proposed the idea that the mass effect of the eddies is entirely similar to that of molecules except for a scale difference. (wikipedia.org)
Diffusion, or brownian movement, denotes the random motion of molecules. (medscape.com)
The diffusion ellipsoid defines the magnitude and direction of the diffusion of water molecules in each voxel in the brain. (medscape.com)
The eigenvector corresponding to the largest eigenvalue, termed the principal eigenvector, defines the main direction of diffusion of water molecules in that voxel (see the image below). (medscape.com)

Diffusion of innovations theory and work-site AIDS programs. (ahrq.gov)
Explaining diffusion patterns for complex health care innovations. (ahrq.gov)
Diffusion of innovations in service organizations: systematic review and recommendations. (ahrq.gov)
Paper presented at Accelerating Quality Improvement in Health Care: Strategies to Accelerate the Diffusion of Evidence-Based Innovations. (ahrq.gov)
2003). Diffusion of innovations (5th ed. (ahrq.gov)
There were a few studies that fit the classical research to practice paradigm and monitored the diffusion of technical innovations but they were unrelated to safety across the residential construction industry (described on page 72 in #5 - What work s best to diffuse non-occup. (cdc.gov)

In particular, these studies include eddy diffusion mechanisms to explain processes from aerosols deposition to internal gravity waves in the upper atmosphere, from deep sea eddy diffusion and buoyancy to nutrient supply to the surface of the mixed layer in the Antarctic Circumpolar Current. (wikipedia.org)
FLOATSUBSCRIPT of early Mars could be vertically transported by eddy diffusion to the floor, whereby dry deposition and precipitation remove it. (medstabs4you.com)

One of the success of eddy viscoity, is it can give a logrithmic boundary layer solution. (cfd-online.com)
O.A. Ladyženskaja, Modification of the Navier-Stokes equations for large velocity gradients, in Seminars in Mathematics V.A. Stheklov Mathematical Institute , Vol. 7, Boundary value problems of mathematical physics and related aspects of function theory, Part II, O.A. Ladyženskaja Ed., New York, London (1970). (esaim-m2an.org)
Stable conditions at night increased suppression of boundary layer mixing by the nonlocal Yonsei University (YSU) scheme when compared with suppression by the local eddy-diffusion component of the Asymmetric Convective Model, version 2 (ACM2), scheme, resulting in decreased wind speed and ambient temperature but moister air with the YSU scheme. (ametsoc.org)

To address this question, we present a novel approach that combines direct tracer measurements of entire white matter trajectories in macaque monkeys with diffusion MRI tractography of both macaques and humans. (jneurosci.org)
The approach allows us to provide explicit validation of diffusion tractography and transfer tractography strategies across species to test the extent to which inferences from macaques can be applied to human neuroanatomy. (jneurosci.org)
We use a novel combination of accurate mapping of whole WM trajectories from chemical tracing, with diffusion MRI tractography. (jneurosci.org)

This causes the fluid properties to homogenize on scale larger than that of eddies responsible for stirring, in a very efficient way compared to individual molecular motion. (wikipedia.org)
In contrast, statistical diffusion theories follow the motion of fluid particles, and are thus Lagrangian. (wikipedia.org)
Later research (1930s), mainly by O. G. Sutton, pointed out some problems of the original approach and put forward the idea that the difference between the eddy structure of a turbulent fluid and the molecular structure of a fluid at rest is more than one of scale. (wikipedia.org)
Axial fluid-attenuated inversion recovery (FLAIR) image (top left), diffusion-weighted image (DWI) (top right), and axial and sagittal T1-weighted (T1W) images (bottom) in a 40-year-old man with a history of intravenous drug abuse and fever demonstrate multiple enhancing focal brain lesions in the gray-white matter junction (arrow) compatible with septic emboli. (medscape.com)
Axial diffusion-weighted image (DWI) (top left), T2-weighted (T2W) image (top right), fluid-attenuated inversion recovery (FLAIR) image (bottom left), and contrast-enhanced T1W (bottom right) image demonstrate a right convexity meningioma, which appears hypointense on DWI image. (medscape.com)

In particular, experiments on the diffusion of foreign material in a turbulent water stream, vertical structure of water in lake bodies, and lowest part of the atmosphere found experimental evidence that eddy diffusion is indeed stronger than molecular diffusion and generally obeys the theory originally developed by G. I. Taylor. (wikipedia.org)
In this paper, we revisit Fick's original diffusion experiments and reconstruct the geometry of his inverted funnel. (scirp.org)
Patzek, T. (2014) Fick's Diffusion Experiments Revisited -Part I. Advances in Historical Studies , 3 , 194-206. (scirp.org)

The theory of eddy diffusion was originally developed, around the end of the 1910s, by G. I. Taylor and L. F. Richardson in England and by W. Schmidt in Austria as a direct generalization of the classical theory of molecular diffusion. (wikipedia.org)

A novel version of this test involves a quantitative diffusion gradient, or Epsilometer (E-test), and uses an absorbent strip with a known gradient of antibiotic concentrations along its length. (medscape.com)

Diffusion is termed isotropic if the motion is equal in all directions. (medscape.com)
This is sufficient for pathologies in areas such as gray matter, where diffusion is usually isotropic. (medscape.com)

Diffusion-weighted imaging (DWI) is a well-established magnetic resonance imaging (MRI) method for diagnosing cerebral ischemia. (medscape.com)

[ 4 ] as well as revealing opposing patterns of diffusion changes in frontal and cerebellar regions of COVID-19 patients, suggesting the 2 regions react differently to viral infection. (medscape.com)

Roger's theory of innovation diffusion 9 identified that the success of new technologies is determined to a great extent by the acceptance by early adopters. (cfp.ca)

During the following decades, a number of studies were carried out to experimentally probe the established theory on eddy diffusion, both for the atmosphere and the ocean/lake bodies, mostly finding agreement with the original theory. (wikipedia.org)
There was controversy in the review articles about which research studies met basic quality control criteria for intervention evaluation and about which of those studies that met the criteria actually work ed to get changes adopted and to reduce injuries. (cdc.gov)

Around 1900 there were large activities in the colloid area and even Einstein in the year of 1905 also published the classical theoretical analysis of brownian motion at equilibrium and those who made the fi rst advances in biochemistry at this time often identifi ed themselves as colloid scientists. (lu.se)

Clinical use of the Stejskal-Tanner diffusion weighted images is hampered by the geometric distortions that result from the large residual 3-D eddy current field induced. (univr.it)
The predicted 3-D eddy current field induced by the diffusion-weighting gradients was able to reduce the root mean square error of the residual eddy current field to ~1 Hz. (univr.it)
Characterization of the 3-D eddy current field with linear response theory enables the prediction of the 3-D eddy current field required to correct eddy current induced geometric distortions for a wide range of clinical and high b-value protocols. (univr.it)
limiting diffusion current' in IUPAC Compendium of Chemical Terminology , 3rd ed. (iupac.org)

Diffusion-weighted imaging has been shown to be useful in the investigation of brain disorders such as epilepsy , multiple sclerosis , brain abscesses , brain tumors, mild traumatic brain injury, and hypertensive encephalopathy (see the images below). (medscape.com)

Diffusion in structured tissue such as white matter is anisotropic. (medscape.com)

E. Lamballais, O. Métais and M. Lesieur, Spectral-dynamic model for large-eddy simulations of turbulent rotating channel flow. (esaim-m2an.org)

Local content requirements for renewable energy can increase domestic support for climate policy, but are also a barrier to diffusion. (lu.se)

Disk diffusion method. (medscape.com)

The theory of eddy diffusion was first developed by Sir Geoffrey Ingram Taylor. (wikipedia.org)

This could start with common long-term deep decarbonisation visions, later strengthened by support for research, development, and diffusion of technologies and infrastructure planning. (lu.se)

Some may say, diffusion is the macroscale behavior of thermo-motion, then is diffusion the only macroscale behavior when we apply the continuity assumption? (cfd-online.com)

However, water diffuses asymmetrically in the white matter-that is, diffusion is restricted perpendicular to the long axis of the axons. (medscape.com)

DTI allows clinicians to look at anisotropic diffusion in white-matter tracts, but it is limited in its ability to demonstrate spatial and directional anisotropy. (medscape.com)

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