A Measure of Control for Secondary Cytokine-Induced Injury of Articular Cartilage: A Computational Study

In previous works, the author and collaborators establish a mathematical model for injury response in articular cartilage. In this paper we use mathematical software and computational techniques, applied to an existing model to explore in more detail how the behavior of cartilage cells is influenced by several of, what are believed to be, the most significant mechanisms underlying cartilage injury response at the cellular level. We introduce a control parameter, the radius of attenuation, and present some new simulations that shed light on how inflammation associated with cartilage injuries impacts the metabolic activity of cartilage cells. The details presented in the work can help to elucidate targets for more effective therapies in the preventative treatment of post-traumatic osteoarthritis

Molecular dynamics for fluid mechanics in arbitrary geometries

Simulations of nanoscale systems where fluid mechanics plays an important role are required to help design and understand nano-devices and biological systems. A simulation method which hybridises molecular dynamics (MD) and continuum computational fluid dynamics (CFD) models is able to accurately represent the relevant physical phenomena and be computationally tractable. An MD code has been written to perform MD simulations in systems where the geometry is described by a mesh of unstructured arbitrary polyhedral cells that have been spatially decomposed into irregular portions for parallel processing. The MD code that has been developed may be used for simulations on its own, or may serve as the MD component of a hybrid method. The code has been implemented using OpenFOAM, an open source C++ CFD toolbox (www.openfoam.org). The requirements for two key enabling components are described. 1) Parallel generation of initial configurations of molecules in arbitrary geometries. 2) Calculation of intermolecular pair forces, including between molecules that lie on mesh portions assigned to different, and possibly non-neighbouring processors. A case study of flow in a realistic nanoscale mixing channel, where the geometry is drawn and meshed in engineering CAD tools is simulated to demonstrate the capabilities of the code

A Unified Term for Directed and Undirected Motility in Collective Cell Invasion

In this paper we develop mathematical models for collective cell motility. Initially we develop a model using a linear diffusion-advection type equation and fit the parameters to data from cell motility assays. This approach is helpful in classifying the results of cell motility assay experiments. In particular, this model can determine degrees of directed versus undirected collective cell motility. Next we develop a model using a nonlinear diffusion term that is able capture in a unified way directed and undirected collective cell motility. Finally we apply the nonlinear diffusion approach to a problem in tumor cell invasion, noting that neither chemotaxis or haptotaxis are present in the system under consideration in this article

Controllers for imposing continuum-to-molecular boundary conditions in arbitrary fluid flow geometries

We present a new parallelised controller for steering an arbitrary geometric region of a molecular dynamics (MD) simulation towards a desired thermodynamic and hydrodynamic state. We show that the controllers may be applied anywhere in the domain to set accurately an initial MD state, or solely at boundary regions to prescribe non-periodic boundary conditions (PBCs) in MD simulations. The mean molecular structure and velocity autocorrelation function remain unchanged (when sampled a few molecular diameters away from the constrained region) when compared with those distributions measured using PBCs. To demonstrate the capability of our new controllers, we apply them as non-PBCs in parallel to a complex MD mixing nano-channel and in a hybrid MD continuum simulation with a complex coupling region. The controller methodology is easily extendable to polyatomic MD fluids

A concurrent precursor inflow method for Large Eddy Simulations and applications to finite length wind farms

In order to enable simulations of developing wind turbine array boundary layers with highly realistic inflow conditions a concurrent precursor method for Large Eddy Simulations is proposed. In this method we consider two domains simultaneously, i.e. in one domain a turbulent Atmospheric Boundary Layer (ABL) without wind turbines is simulated in order to generate the turbulent inflow conditions for a second domain in which the wind turbines are placed. The benefit of this approach is that a) it avoids the need for large databases in which the turbulent inflow conditions are stored and the correspondingly slow I/O operations and b) we are sure that the simulations are not negatively affected by statically swept fixed inflow fields or synthetic fields lacking the proper ABL coherent structures. Sample applications are presented, in which, in agreement with field data a strong decrease of the power output of downstream wind-turbines with respect to the first row of wind-turbines is observed for perfectly aligned inflow.Comment: 13 pages, 5 figure

Effects Of Fatigue On The Balance Error Scoring System For Concussion Testing In Healthy And Previous Concussed Participants

There has been a recent increase in the attention of concussions in the media and research world. One of the major factors that contribute to injuries including concussion is fatigue. This study has been designed to allow athletic trainers to decipher whether a potential balance insufficiency in an acutely concussed athlete is due to fatigue or the side affects of the concussion on postural stability. The study examined 30 college-aged athletes from a multitude of sports who had either sustained a concussion or never had a concussion. Participants were randomly grouped into one of three groups: non-concussed control group, non-concussed treatment group, or a concussed treatment group. The participants completed a pretest of the Balance Error Scoring System (BESS) followed three days later by a fatigue protocol for those in the treatment groups and finished by completing a posttest BESS. The fatigue protocol is a seven station circuit program that has been utilized in past research studies using the Rating of Perceived Exertion (RPE) scale to measure fatigue. The results showed no significant difference in BESS scores from the pretest to posttest in any of the sample groups. There was a significant difference (p=.000) in RPE scores between the two treatment groups and the control group. These results indicate there was significant fatigue induced for the BESS posttest in the treatment groups. However, fatigue did not appear to influence the BESS test for either non-concussed or concussed participants

Generativity: Lived Experience as Curricular Content

This article explores notions of work and emergence in relation to our experience of being in the world. The article takes the notion of work as something more than the mere occupations of students, reorienting it in the literature of Zen Buddhism, Marxism, and chaos mathematics. Lived experience seeks to shed light on the growing dissociation between student and curricular content and provides a concrete, practical example that suggests the possibility that both learner and learned are transformed through difficult, meaningful, and local work.Cette étude se penche sur les notions de travail et d'émergence par rapport à notre vécu. Dans l'article, on présente la notion du travail comme une réalité dépassant une simple occupation des élèves pour la réorienter selon les pensées du Bouddhisme Zen, du Marxisme et de la théorie mathématique du chaos. Le vécu cherche à éclairer la dissociation croissante entre l'élève et le contenu du curriculum tout en fournissant un exemple concret et pratique qui propose la possibilité que l'élève et l'enseignant sont tous les deux transformés par le travail ardu, significatif et local