Impact of Hospital Inventory Management of PPE on State-Level Healthcare Worker Infections during the COVID-19 Pandemic

The COVID-19 pandemic has put a spotlight on the personal protective equipment (PPE) supply chain and its inability to keep up with the fluctuating demands of a global pandemic. Limited research examines the resilience of the PPE supply chain in times of stress, and very few studies rely on quantitative retrospective analysis. This dissertation studies the impact of hospital inventory management, a portion of PPE supply chain preparedness, on infections in healthcare workers (HCWs). Our research shows that there exists a statistically significant negative relationship between PPE preparedness and infections for HCWs, but this relationship is only significant for N95 masks, surgical masks, and gloves. This suggests the importance of hospital inventory management of PPE in the prevention of infections for HCWs is not equal for all types of PPE and in times of stress, practitioners may be able to focus on the elements of PPE that prevent infection

Synthesis of new 3,4-dihydropyrano[c]chromene derivatives and their evaluation as acetyl cholinesterase inhibitors

2-Amino-4-phenyl-4,5-dihydro-5-oxopyrano[2,3-c]chromen-3-carbonitrile derivatives (8a-d) have been isolated in good yields by the reaction of corresponding 4-hydroxycoumarin (1) with substituted aldehydes (2a-d) and malononitrile (3) under reflux conditions. The reactivity of α-functionalized iminoethers (9a-d) with hydrazine, hydroxylamine and piperidine was studied. The synthesized compounds were characterized by various techniques including spectroscopy. Compounds 8-11 were also evaluated as potential acetylcholinesterase inhibitors

Comparison of parametric methods for modeling corneal surfaces

Corneal topography is a medical imaging technique to get the 3D shape of the cornea as a set of 3D points of its anterior and posterior surfaces. From these data, topographic maps can be derived to assist the ophthalmologist in the diagnosis of disorders. In this paper, we compare three different mathematical parametric representations of the corneal surfaces leastsquares fitted to the data provided by corneal topography. The parameters obtained from these models reduce the dimensionality of the data from several thousand 3D points to only a few parameters and could eventually be useful for diagnosis, biometry, implant design etc. The first representation is based on Zernike polynomials that are commonly used in optics. A variant of these polynomials, named Bhatia-Wolf will also be investigated. These two sets of polynomials are defined over a circular domain which is convenient to model the elevation (height) of the corneal surface. The third representation uses Spherical Harmonics that are particularly well suited for nearly-spherical object modeling, which is the case for cornea. We compared the three methods using the following three criteria: the root-mean-square error (RMSE), the number of parameters and the visual accuracy of the reconstructed topographic maps. A large dataset of more than 2000 corneal topographies was used. Our results showed that Spherical Harmonics were superior with a RMSE mean lower than 2.5 microns with 36 coefficients (order 5) for normal corneas and lower than 5 microns for two diseases affecting the corneal shapes: keratoconus and Fuchs’ dystrophy

Spatiotemporal Modelling of Multi-Gateway LoRa Networks with Imperfect SF Orthogonality

Meticulous modelling and performance analysis of Low-Power Wide-Area (LPWA) networks are essential for large scale dense Internet-of-Things (IoT) deployments. As Long Range (LoRa) is currently one of the most prominent LPWA technologies, we propose in this paper a stochastic-geometry-based framework to analyse the uplink transmission performance of a multi-gateway LoRa network modelled by a Matern Cluster Process (MCP). The proposed model is first to consider all together the multi-cell topology, imperfect spreading factor (SF) orthogonality, random start times, and geometric data arrival rates. Accounting for all of these factors, we initially develop the SF-dependent collision overlap time function for any start time distribution. Then, we analyse the Laplace transforms of intra-cluster and inter-cluster interference, and formulate the uplink transmission success probability. Through simulation results, we highlight the vulnerability of each SF to interference, illustrate the impact of parameters such as the network density, and the power allocation scheme on the network performance. Uniquely, our results shed light on when it is better to activate adaptive power mechanisms, as we show that an SF-based power allocation that approximates LoRa ADR, negatively impacts nodes near the cluster head. Moreover, we show that the interfering SFs degrading the performance the most depend on the decoding threshold range and the power allocation scheme.Comment: IEEE Global Communications Conferenc

Reduction method applied to viscoelastically damped finite element models

International audienceWe propose in this paper to combine the GHM (Golla-Hughes-Mc Tavish) method with model reduction technique, especially direct condensation methods to resolve the problem of increased model order of viscoelastically structures. In fact, modeling structures using the GHM method leads to global systems of equation of motion whose numbers of degrees-offreedom largely exceeds the order of the associated undamped system. As result, the numerical resolution of such equations can require prohibitive computational (CPU) time. So, to overcome this problem, both Static and Dynamic methods are used to reduce the order of finite elements matrices while preserving its capability to represent the dynamic behavior of viscoelastically damped structures. This paper intends to compare these two methods in direct reduction. Numerical example applied to cantilever beam structure is presented. This example will highlight the domain of validity of the studied methods. Results obtained from these two reduction methods are compared with the full model in order to illustrate its performances and its practical interest in the dynamic analysis of viscoelastically damped structures