The influence of randomness on wave propagation in one-dimensional chains of spherical granular media is investigated. The interaction between the elastic spheres is modeled using the classical Hertzian contact law. Randomness is introduced in the discrete model using random distributions of particle mass, Young's modulus, or radius. Of particular interest in this study is the quantification of the attenuation in the amplitude of the impulse associated with various levels of randomness: two distinct regimes of decay are observed, characterized by an exponential or a power law, respectively. The responses are normalized to represent a vast array of material parameters and impact conditions. The virial theorem is applied to investigate the transfer from potential to kinetic energy components in the system for different levels of randomness. The level of attenuation in the two decay regimes is compared for the three different sources of randomness and it is found that randomness in radius leads to the maximum rate of decay in the exponential regime of wave propagation.
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http://dx.doi.org/10.1103/PhysRevE.85.031308 | DOI Listing |
Heart Rhythm
January 2025
Department of Molecular Biosciences, University of California, Davis, CA, USA; Department of Basic Sciences, California Northstate University, Elk Grove, CA. Electronic address:
Background: Friedreich's ataxia (FA) is a rare inherited neuromuscular disorder, where most patients die from lethal cardiomyopathy and arrhythmias. Mechanisms leading to arrhythmic events in FA patients are poorly understood.
Objective: This study aims to examine cardiac electrical signal propagation in mouse model of FA with severe cardiomyopathy and evaluate effects of omaveloxolone (OMAV), the first FDA-approved therapy.
Transl Vis Sci Technol
December 2024
Department of Biomedical Engineering, University of Houston, Houston, TX, USA.
Purpose: To assess the safety of acoustic radiation force optical coherence elastography in the crystalline lens in situ.
Methods: Acoustic radiation force (ARF) produced by an immersion single-element ultrasound transducer (nominal frequency = 3.5 MHz) was characterized using a needle hydrophone and used for optical coherence elastography (OCE) of the crystalline lens.
Biomed Eng Lett
January 2025
Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919 Republic of Korea.
Unlabelled: Patients suffering from various neurological disorders, including major depressive disorder (MDD), often exhibit abnormal brain connectivity. In particular, patients with MDD show atypical brain oscillations propagation. This study aims to investigate an association between abnormal brain connectivity and atypical oscillatory propagation of electroencephalogram (EEG) signals in patients with a history of MDD.
View Article and Find Full Text PDFExp Neurol
January 2025
Department of Neurology, University of Virginia, Charlottesville, VA 22908, USA; Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA; UVA Brain Institute, University of Virginia, Charlottesville, VA 22908, USA.
Migraine patients often experience sensory symptoms called auras accompanying the headaches. Cortical spreading depression (CSD), a slow-propagating wave of neuroglial depolarization followed by hyperpolarization is proposed to be the neurological mechanism underlying these auras. We have previously found that progesterone regulates susceptibility to migraine through progesterone receptor (PR) activation.
View Article and Find Full Text PDFJ Magn Reson Imaging
February 2025
BioMedical Engineering and Imaging Institute, Icahn School of Medicine Mount Sinai, New York, New York, USA.
Background: Several factors can impair image quality and reliability of liver magnetic resonance elastography (MRE), such as inadequate driver positioning, insufficient wave propagation and patient-related factors.
Purpose: To report initial results on automatic classification of liver MRE image quality using various deep learning (DL) architectures.
Study Type: Retrospective, single center, IRB-approved human study.
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