Failure characteristics of all polyethylene cemented glenoid implants in total shoulder arthroplasty

Total shoulder arthroplasty (TSA) still suffers today from mid-term and long-term complications such as glenoid implant loosening, wear, humeral head subluxation/dislocation and implant fracture. Unlike the hip and knee joint replacements, the artificial shoulder joint has yet to offer a long-term satisfactory solution to shoulder replacement. With loosening being the number one reason for TSA revision, investigating methods of monitoring the glenoid implant loosening and investigate the effects of various design parameters on the loosening behaviour of the glenoid fixation is necessary to explore the problem. Several studies were carried out using in-vitro cyclic testing and FEA to; investigate failure progression and its correlation to quantitative measures in a 2D study (n = 60), investigating key glenoid design features in a 2D (n = 60) and 3D study (n = 20), investigating the validity of using bone substitute foam for studying glenoid fixation in a cadaveric study and investigating any correlation between failure and CT or in-vitro quantitative measures (n = 10). Visible failure was observed, for the first time, correlating to inferior rim displacement and vertical head displacement measures. CT failure was detected in 70% of specimens before visible failure was observed. Out of the design pairs tested; smooth-back/rough-back (range of roughnesses), peg/keel, curved-back/flat-back and conforming/non-conforming, roughening the back-surface to 3.4 μm or more improved fixation performance (p < 0.05). Roughening the back-surface changed the mode of failure from implant/cement failure inferiorly due to tensile/shear stresses, to cement/bone failure superiorly due to compressive/shear loading. Differences in the other design pairs were marked showing peg to perform better than keel, conforming over non-conforming and no difference in curved-back over flat-back, although these differences are marginal. Improvements in the standard testing method have also been suggested

Learning 101: The untaught basics

Despite the accessibility of a wealth of information in the current era-books, universities, and online massive open online courses (MOOCs)-well-intentioned and hard-working students often fail to learn effectively due to deficient learning techniques or improper mind-sets. Two things, in particular, hinder students from achieving their potential. First, the students' intuition regarding how learning works is often flawed and counterproductive; second, despite significant progress in the research discipline of "learning sciences," these hard-earned scientific insights have not yet filtered their way through the research community to the students who stand to benefit most from this knowledge

Temporal Behavior of the Individual Soft Microparticles: Understanding the Detection by Particle Impact Electrochemistry

Emerging progress of the Particle Impact Electrochemistry (PIE) technique has opened a novel field of detection and characterization of many analyte particles. 1 PIE comprises detection of changes in current when collisions of individual micro or nanoparticles are linked with an electrochemical event at the surface of an ultramicroelectrode (UME). 2 Being a rapid, low cost, and analyzing of one analyte at a time, PIE is widely used to characterize the shape, size distribution, and catalytic activity of nanoparticles. 2-5 To explore the scope of PIE for the detection of soft microparticles (absence of crystalline structure), ferrocene (Fc) trapped toluene-in-water emulsion droplets was used as a model with ultramicroelectrode. Droplets were analyzed by tracking the oxidation of Fc inside the droplet in the presence of an ionic liquid acting as emulsifier and conductivity enhancer. The droplet diameter was determined electrochemically using Faraday’s law. PIE was able to characterize the polydisperse size distribution of the droplets successfully. A 3D lattice random walk simulation indicated the stochastic nature of the droplet motion. Unlike nanoparticles, the droplets have slow kinetics and the collision dynamics associated with adsorption on the electrode surface. The adsorbing droplet generated similar spike-like electrical signals in real-time experiments that follow the bulk electrolysis model. These findings will facilitate the characterization of polydisperse microparticles including bacteria, which also adsorb and have similar size and density as the droplets in this work. Finally, because electrolysis time spans from hundreds of milliseconds to a second, single events of such duration are detectable with present-day instrumentation in contrast to non-adsorbing nanoparticles that have nanosecond collisions.https://scholarscompass.vcu.edu/gradposters/1057/thumbnail.jp

On the Secure and Reconfigurable Multi-Layer Network Design for Critical Information Dissemination in the Internet of Battlefield Things (IoBT)

The Internet of things (IoT) is revolutionizing the management and control of automated systems leading to a paradigm shift in areas such as smart homes, smart cities, health care, transportation, etc. The IoT technology is also envisioned to play an important role in improving the effectiveness of military operations in battlefields. The interconnection of combat equipment and other battlefield resources for coordinated automated decisions is referred to as the Internet of battlefield things (IoBT). IoBT networks are significantly different from traditional IoT networks due to battlefield specific challenges such as the absence of communication infrastructure, heterogeneity of devices, and susceptibility to cyber-physical attacks. The combat efficiency and coordinated decision-making in war scenarios depends highly on real-time data collection, which in turn relies on the connectivity of the network and information dissemination in the presence of adversaries. This work aims to build the theoretical foundations of designing secure and reconfigurable IoBT networks. Leveraging the theories of stochastic geometry and mathematical epidemiology, we develop an integrated framework to quantify the information dissemination among heterogeneous network devices. Consequently, a tractable optimization problem is formulated that can assist commanders in cost effectively planning the network and reconfiguring it according to the changing mission requirements.Comment: to appear in IEEE Transactions on Wireless Communications. arXiv admin note: substantial text overlap with arXiv:1703.0122