On the Numerical Solution for Two Dimensional Laplace Equation with Initial Boundary Conditions by using Finite Difference Methods

In this study, Laplace partial differential equations with initial boundary conditions has been studied. A numerical method has been proposed for the solution of the IBVP Laplace equation. The technique based on finite difference methods. The stability of the difference schemes are guaranteed. Approximation solution of the problem was achieved. For testing the accuracy of the proposed method, two different initial boundary value problems are provided. Moreover, a comparison between the numerical solution and analytical solution has been done. MATLAB software implemented for calculation of absolute errors. Illustration graphs presented. It has been demonstrated that the results of the comparison guarantee the accuracy and reliability of the provided method

Numerical Solution for Time Period of Simple Pendulum Under Magnetic Field

In the present study, the numerical solution of the time period of a Simple Pendulum under a magnetic field investigated. The analytical solution presented for the given problem. The numerical solution for the problem achieved by using two numerical quadrature methods, namely, Simpson’s 3/8 and Boole’s method. The period of a simple pendulum with a large angle is presented. The results of the numerical quadrature have been compared to the exact solution. Absolute and relative mistakes of the problem have been presented. The Matlab program 2013R has created a numerical method to analyze the outcome. Moreover, it is established that the comparison results guarantee the present method's ability and accuracy

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

Mortality of emergency abdominal surgery in high-, middle- and low-income countries

Background: Surgical mortality data are collected routinely in high-income countries, yet virtually no low- or middle-income countries have outcome surveillance in place. The aim was prospectively to collect worldwide mortality data following emergency abdominal surgery, comparing findings across countries with a low, middle or high Human Development Index (HDI). Methods: This was a prospective, multicentre, cohort study. Self-selected hospitals performing emergency surgery submitted prespecified data for consecutive patients from at least one 2-week interval during July to December 2014. Postoperative mortality was analysed by hierarchical multivariable logistic regression. Results: Data were obtained for 10 745 patients from 357 centres in 58 countries; 6538 were from high-, 2889 from middle- and 1318 from low-HDI settings. The overall mortality rate was 1⋅6 per cent at 24 h (high 1⋅1 per cent, middle 1⋅9 per cent, low 3⋅4 per cent; P < 0⋅001), increasing to 5⋅4 per cent by 30 days (high 4⋅5 per cent, middle 6⋅0 per cent, low 8⋅6 per cent; P < 0⋅001). Of the 578 patients who died, 404 (69⋅9 per cent) did so between 24 h and 30 days following surgery (high 74⋅2 per cent, middle 68⋅8 per cent, low 60⋅5 per cent). After adjustment, 30-day mortality remained higher in middle-income (odds ratio (OR) 2⋅78, 95 per cent c.i. 1⋅84 to 4⋅20) and low-income (OR 2⋅97, 1⋅84 to 4⋅81) countries. Surgical safety checklist use was less frequent in low- and middle-income countries, but when used was associated with reduced mortality at 30 days. Conclusion: Mortality is three times higher in low- compared with high-HDI countries even when adjusted for prognostic factors. Patient safety factors may have an important role. Registration number: NCT02179112 (http://www.clinicaltrials.gov)

MHD Flow and Heat Transfer in a Casson Fluid Over A Nonlinearly Stretching Sheet With Newtonian Heating

The magnetohydrodynamic (MHD) flow of a Casson fluid and heat transfer to a nonlinearly stretching sheet with Newtonian heating are studied. With the help of similarity transformations, the governing equations are converted into nonlinear ordinary differential equations. The Runge–Kutt a–Fehlberg fourth-fifth order (RKF45) method is employed to obtain numerical solutions for the velocity and temperature distributions. Closed form analytical solutions are also obtained. The resulting velocity and temperature are shown graphically and discussed for the case of a uniform moving surface, a linearly or nonlinearly stretching sheet. The present results are also compared with the previous results for a Newtonian fluid. The results show that the velocity field is much more pronounced in the case of a uniformly moving surface as compared to a linearly stretching sheet or a nonlinearly stretching sheet. It is also found that the Casson fluid have higher velocity than the Newtonian fluid

Les réseaux biodégradables autocicatrisants utilisant des monomères biosourcés par réactions de Diels-Alder

Ce mémoire de thèse a pour objectif l'élaboration de réseaux élastomères thermoreversibles. Ces réseaux à base de polycaprolactone (PCL), dont la plupart des constituants sont issus de la biomasse, auront la particularité d'être recyclables et biodégradablesThe aim of this thesis is to elaboration of the thermoreversible elastomers networks. These polycaprolactone-based networks (PCL-based networks), most of which of the constituents from biomass, will have the particularity of being recyclable and biodegradableST ETIENNE-Bib. électronique (422189901) / SudocSudocFranceF

One-step Synthesis of PCL-Urethane Networks using a Crosslinking/de-crosslinking Agent

International audienceThermally reversible cross-linked polycaprolactone-urethane (PCL-U) was prepared in one-step procedure. The PCL-U networks were synthesized from a di-isocyanate (4,4-methylene bis(cyclohexylisocyanate) (HMDI) and hydroxyl bearing macromers and monomers: hydroxy-terminated PCL, glycerol and a di-alcohol Diels-Alder (DA) adduct. This adduct was used to introduce both diene and dienophile functions in the structure and also to protect the maleimide functions from polymerization. The thermoresponsive behavior of the material was characterized by commonly used methods such as solubility tests at different temperatures and differential scanning calorimetry analyses to highlight rDA reactions and also by rheological analysis. The effects of the cooling rate, the molar mass of polycaprolactone as well as the molar ratio [di-Isocyanate]/[PCL-diol] on the cross-linking/de-cross-linking temperatures were also analyzed. The reversible networks obtained have a self-healing behavior