Rolling Friction in Loose Media and its Role in Mechanics Problems

Rolling friction between particles is to be set in problems of granular material mechanics alongside with sliding friction. A classical problem of material passive lateral pressure on the retaining wall is submitted as a case in point. 3D method of discrete elements was employed for numerical analysis. Material is a universe of spherical particles with specified size distribution. Viscose-elastic properties of the material and surface friction are included, when choosing contact forces. Particles' resistance to rolling relative to other particles and to the boundary is set into the model. Kinetic patterns of medium deformations are given. It has been proved that rolling friction can significantly affect magnitude and nature of passive lateral pressure on the retaining wall

26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15–20 July 2017

This work was produced as part of the activities of FAPESP Research,\ud Disseminations and Innovation Center for Neuromathematics (grant\ud 2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud supported by a CNPq fellowship (grant 306251/2014-0)

Supplementary code for paper "Translating from Na+ to Ca2+: Na/Ca-exchanger exerts Na+-dependent control over astrocytic Ca2+ oscillations"

<p>Recently accumulated evidence suggest that astrocyte signaling is linked to extracellular volume regulation and interstitial fluid drainage from the brain. Classical understanding of astrocyte activity is based on IP<sub>3</sub>-dependent calcium exchange with intracellular stores. Recent evidence shifts focus to calcium entry from extracellular space via multiple mechanisms and widens it to taking other ions into account.</p> <p>It has been hypothesized that Na/Ca-exchanger can translate activity-dependent Na<sup>+</sup> transients into modulation of Ca<sup>2+</sup> dynamics. We combine a model of IP<sub>3</sub> based  Ca<sup>2+</sup>  dynamics with a model of Ca<sup>2+</sup> flow through Na/Ca-exchanger to provide theoretical insights into the possible effects of such modulation. We find that the exchanger can provide for bidirectional Na<sup>+</sup>-dependent modulation of the sensitivity to extracellular glutamate, oscillation amplitude and frequency modulation, as well as extending the available set of dynamical regimes. The extent of the emergent Na<sup>+</sup> sensitivity is predicted to be scaled by a morphology-dependent balance between the maximal flow through the exchanger and the rate of entry from intracellular stores.</p> <p>This is the accompanying code used for the paper. How to run:<br> 1. Install Anaconda https://www.anaconda.com/products/individual<br> 2. Go to the folder with the code<br> 3. In anaconda prompt, create environment with dependencies: `conda env create -f astro-ncx-env.yaml`<br> 4. Unpack pre-computed model behavior characteristics: `tar zxf data.tgz`<br> 5. Activate the created environment: `conda activate astro-ncx`<br> 6. In anaconda prompt, use Jupyter lab server to run the attached notebook: `jupyter lab NCX+Ullah_model.ipynb`</p&gt