The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

SOFC fuel cell heat production: Analysis

In the present work the effect of various heat sources on the temperature field within an Anode Supported Planar Solid Oxide Fuel Cell (ASP-SOFC) is studied. In order to describe the thermal behavior within the SOFC during its operation, the coupling of the mass and energy transport phenomena along with the electrochemistry is required. More precisely, the subject of the present analysis is the visualization of the temperature field and the location of the highest temperatures within an ASP-SOFC fed with hydrogen and air. The studied parameters are: i) the temperature values of the reactants and ii) the different types of the heat sources; due to the over potentials, the Joule effect and the water formation. The complex system of the governing equations is numerically solved with the finite differences method and the temperature field within each domain of the ASP-SOFC is calculated via a mathematical model implemented in FORTRAN language. The mathematical model predictions for the temperature gradient within the ASP-SOFC under the influence of the studied parameters are thoroughly discussed. © 2010 Published by Elsevier Ltd

Two-dimensional numerical study of temperature field in an anode supported planar SOFC: Effect of the chemical reaction

In the present work the effect of the chemical reaction on the temperature field in an anode supported planar SOFC is numerically studied by the aid of a two-dimensional mathematical model. For the model development the mass transport phenomena, the energy conservation, the species flow governed by Darcy's law and the electrochemistry are coupled. The finite difference method is used to solve numerically the system of the equations. The temperature field within each component of the SOFC (interconnection, cathode, anode and electrolyte) is calculated via the mathematical model which is implemented in FORTRAN language. The model results demonstrate the effect of different expressions of the chemical heat source, expressed in terms of enthalpy and entropy, on the temperature field and the location of the higher temperatures that occur within the SOFC during its operation. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Alternative current conduction, dielectric behavior, transport properties and Mössbauer study of LaBaFe0.5Ti0.5MnO6-δ new compound

International audienc

A novel approach to study the isothermal and non-isothermal crystallization kinetics of Poly(Ethylene Terephthalate) by Raman spectroscopy

International audienc

Galectin 3 exerts a protective role in a murine model of osteoarthritis

International audienc

Occupational Noise Exposure and Diabetes Risk

Introduction. Noise is one of the most common worldwide environmental pollutants, especially in occupational fields. As a stressor, it affects not only the ear but also the entire body. Its physiological and psychological impacts have been well established in many conditions such as cardiovascular diseases. However, there is a dearth of evidence regarding diabetes risk related to noises. Aim. To evaluate the relationship between occupational exposure to noise and the risk of developing diabetes. Methods. This is a cross-sectional analytical study enrolling two groups of 151 workers each. The first group (noise exposed group: EG) included the employees of a Tunisian power plant, who worked during the day shift and had a permanent position. The second group (unexposed to noise group: NEG) included workers assigned to two academic institutions, who were randomly selected in the Occupational Medicine Department of the Farhat Hached University Hospital in Sousse, during periodical fitness to work visits. Both populations (exposed and unexposed) were matched by age and gender. Data collection was based on a preestablished questionnaire, a physical examination, a biological assessment, and a sonometric study. Results. The mean equivalent continuous sound level was 89 dB for the EG and 44.6 dB for the NEG. Diabetes was diagnosed in 24 workers from EG (15.9%) and 14 workers from NEG (9.3%), with no statistically significant difference (p=0.08). After multiple binary logistic regression, including variables of interest, noise did not appear to be associated with diabetes. Conclusion. Our results did not reveal a higher risk of developing diabetes in workers exposed to noise. Further studies assessing both level and duration of noise exposure are needed before any definitive conclusion