2,110 research outputs found
Computational modeling of acute myocardial infarction
This is an Accepted Manuscript of an article published by Taylor & Francis Group in Computer Methods in Biomechanics and Biomedical Engineering on October, 2016, available online at: http://www.tandfonline.com/10.1080/10255842.2015.1105965Myocardial infarction, commonly known as heart attack, is caused by reduced blood supply and damages the heart muscle because of a lack of oxygen. Myocardial infarction initiates a cascade of biochemical and mechanical events. In the early stages, cardiomyocytes death, wall thinning, collagen degradation, and ventricular dilation are the immediate consequences of myocardial infarction. In the later stages, collagenous scar formation in the infarcted zone and hypertrophy of the non-infarcted zone are auto-regulatory mechanisms to partly correct for these events. Here we propose a computational model for the short-term adaptation after myocardial infarction using the continuum theory of multiplicative growth. Our model captures the effects of cell death initiating wall thinning, and collagen degradation initiating ventricular dilation. Our simulations agree well with clinical observations in early myocardial infarction. They represent a first step toward simulating the progression of myocardial infarction with the ultimate goal to predict the propensity toward heart failure as a function of infarct intensity, location, and size.Peer ReviewedPostprint (author's final draft
Small Angular Scale Simulations of the Microwave Sky
We describe and compare two types of microwave sky simulations which are good
for small angular scales. The first type uses expansions in spherical
harmonics, and the second one is based on plane waves and the Fast Fourier
Transform. The angular power spectrum is extracted from maps corresponding to
both types of simulations, and the resulting spectra are appropriately
compared. In this way, the features and usefulness of Fourier simulations are
pointed out. For , all the simulations lead to similar
accuracies; however, the CPU cost of Fourier simulations is times
smaller than that for spherical harmonic simulations. For , the
simulations based on spherical harmonics seem to be preferable.Comment: 16 pages (LATEX), 2 postcript figures. Accepted in Ap
Symplectic matrices with predetermined left eigenvalues
We prove that given four arbitrary quaternion numbers of norm 1 there always
exists a symplectic matrix for which those numbers are left
eigenvalues. The proof is constructive. An application to the LS category of
Lie groups is given.Comment: 7 page
Spherically Symmetric Solutions in M\o ller's Tetrad Theory of Gravitation
The general solution of M\o ller's field equations in case of spherical
symmetry is derived. The previously obtained solutions are verified as special
cases of the general solution.Comment: LaTeX2e with AMS-LaTeX 1.2, 8 page
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