roth b j sepulveda n g and wikswo j p pdf

Roth B J Sepulveda N G And Wikswo J P Pdf

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Published: 18.04.2021

In this study cardiac tissue is stimulated electrically through a small unipolar electrode. Numerical simulations predict that around an electrode are adjacent regions of depolarization and hyperpolarization.

Metrics details. The goal of our study is to examine the effect of stimulating a two-dimensional sheet of myocardial cells. We assume that the stimulating electrode is located in a bath perfusing the tissue.

We present an analysis of the relative information content of cortical current source reconstructions from electroencephalogram EEG and magnetoencephalogram MEG forward calculations by examining the spatial filters that relate the internal sources with the externally measured electric potentials and magnetic fields. The forward spatial filters are seen to be low-pass functions of spatial frequency and spatial resolution degrades in external measurements. Inverse spatial filters may be used to reconstruct cortical sources from external data, but since they are high-pass functions of spatial frequency, they must be regularized to avoid instabilities caused by noise at higher spatial frequencies. The regularization process limits the spatial resolution of source reconstructions. EEG forward spatial filters fall off at lower spatial frequencies than MEG filters; hence, there is less information available in higher spatial frequencies resulting in lower spatial resolution in inverse reconstructions.

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Either your web browser doesn't support Javascript or it is currently turned off. In the latter case, please turn on Javascript support in your web browser and reload this page. Free to read. A two-dimensional sheet of anisotropic cardiac tissue is represented with the bidomain model, and the finite element method is used to solve the bidomain equations. When the anisotropy ratios of the intracellular and extracellular spaces are not equal, the injection of current into the tissue induces a transmembrane potential that has a complicated spatial dependence, including adjacent regions of depolarized and hyperpolarized tissue. This behavior may have important implications for the electrical stimulation of cardiac tissue and for defibrillation. Read article at publisher's site DOI :

Visualization of spatial conductivity irregularities within conductive rubber sheets

Li, D. Over the last few decades, there have been many attempts to measure the corrosion current distribution over a surface during active corrosion, with little success. Since the net anodic current is equal to the net cathodic current in active corrosion, any nonlocal measuring methods would sense a net current approaching zero. The scanning vibrating electrode technique has shown some success in measuring the potential drop between a reference electrode and a scanning vibrating electrode for an actively corroding sample. Their technique was based on the principle that the specific resistance of the solution over a corroding metal is constant and that this solution resistance produces potential fields between local anodic and cathodic sites. There are several problems with the scanning vibrating electrode technique, including: -- The presence of the scanning vibrating electrode in the solution may disturb the corrosion current distribution; -- The scanning vibrating electrode will stir the electrolyte; and finally, -- The specific resistance of the solution over the sample can be different from region to region, particularly for dilute solutions.

Reprinted with permission from Journal of Applied Physics 65 (1), Roth. BJ, Sepulveda NG, Wikswo JP, "Using a Magnetometer to Image a.

Current injection into a two-dimensional anisotropic bidomain.

The purpose of this paper is to present a fast and contactless measurement method to determine the spatial conductivity distribution within an intrinsically conducting polymer, more precisely a conductive rubber sheet specimen. As a consequence of the manufacturing process and the material composition, the conductivity distribution within the sheet is assumed to be inhomogeneous. The current density distribution within the conductive rubber sheet due to an excitation current is estimated from the measured magnetic field distribution. Therefore, a GMR sensor is used to spatially sample the magnetic field above the specimen.

Sunil M. Kandel, Bradley J. The bidomain model describes the electrical properties of cardiac tissue and is often used to simulate the response of the heart to an electric shock. The strength-interval curve summarizes how refractory tissue is excited. This paper analyzes calculations of the strength-interval curve when a stimulus is applied through a unipolar electrode.

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A mathematical model for electrical stimulation of a monolayer of cardiac cells

John Peter Wikswo, Jr. He was born in Lynchburg, Virginia , United States. Wikswo is noted for his work on biomagnetism and cardiac electrophysiology. In the s, Wikswo was a graduate student at Stanford University , where he worked under physicist William M. Fairbank , studying magnetocardiography.

Медсестра была уже совсем близко и что-то кричала Беккеру по-испански, но он ничего не слышал. Его глаза не отрывались от губ Клушара. Он еще раз сжал его руку, но тут наконец подбежала медсестра.


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