Track D Social Science, Human Rights and Political Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

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

Screening constant by unit nuclear charge calculations of

The $_{2}(1,0)_n^{+}$ 1Se, $_{2}(1,0)_{n}^{-}$ 3Se, $_{2}(1,0)_{n}^{-}$ 1P$^{\circ}$, $_{2}(1,0)_{n}^{+}$ 3P$^{\circ}$, $_{2}(0,1)_{n}^{+}$ 1P$^{\circ}$, $_{2}(0,1)_{n}^{-}$ 3P$^{\circ}$, $_{2}(1,0)_{n}^{+}$ 1De and $_{2}(1,0)_{n}^{-}$ 3De intershell autoionizing states of the helium-like ions are studied using the screening constant by unit nuclear charge (SCUNC) method in the framework of a semi-empirical procedure. The results up to Z = 10 compared well to the available experimental and theoretical literature data. In addition, the possibility to apply the SCUNC method in the calculations of energy resonances of heavy-Z helium-like ions is demonstrated in the present work where energy positions for some low-lying 2sns1Se, 2snp1P$^{\circ}$ and 2pnp1De ($n \le 4$) autoionizing states with 11 $\le Z \le 28$ are tabulated and comparison with double sums over the complete hydrogen spectrum calculations [A.I. Ivanov, I.U. Safronova, Opt. Spectrosc. 75, 506 (1993)] is made. A host of results presented in this paper may be useful guideline for future experimental and theoretical investigations in high-lying $^{1,3}$Se, $^{1,3}$P$^{\circ}$ and $^{1,3}$De doubly excited states as well as in lower than in heavy-Z two-electron systems

High-lying

We present in this paper autoionizing energies of the 1P° states of H- and He belonging to the N = 3–13 hydrogenic thresholds. Calculations are performed for both intershell and intrashell resonances using the screening constant by unit nuclear charge (SCUNC) method in the framework of a semi-empirical procedure. The results obtained in this paper agree very well with available theoretical and experimental values. These agreements point out the possibility to use the SCUNC method in the study of other Rydberg-type series in doubly excited states of He-positive like ions

Évolution et fonctionnement hydro-sédimentaire de la lagune de la Somone, Petite Côte, Sénégal.

Thèse de Doctorat soutenue publiquement le 16 septembre 2011 à 14 H, Salle de Conférences de l'UMR-CNRS 6143 M2C, Département de Géologie, Université de Rouen, FRANCELocated at the Petite Côte of Senegal, Somone is a small coastal river that flows into the Atlantic Ocean by a microtidal lagoonal-estuarine ecosystem. Today, the contribution of the watershed is absent due to a combination of several factors including the dam of Bandia. The only freshwater inputs are from precipitation and groundwater. Somone is a lagoonal-estuarine system characterized by an inverse hydrological functioning where marine influences predominate. Mangrove, dominated by Rhizophora, is the main characteristic unit of this coastal system. The diachronic evolution of 60 years shows a significant change for all the morphological units of the ecosystem. The mobility of the sandy spit, which caused the closures of the mouth in 1967-1969 and in 1987, is related to meteorological variations. The regressive surface of mangroves between 1954 and 1989 is the result of the combined effect of these closures of the mouth, drought and traditional uses of mangroves. The restoration of the mangrove is mainly due to reforestation policies administered in the 2000s. The annual and seasonal trend shows that the internal reworking is the main hydro-sedimentary processes. Sedimentation rate of the mud flats is 2 to 3 mm/year. The dynamics of the sandy spit of the Somone plays an important role in the development and quality of internal units, the mangroves in particular. The permanent opening of the mouth allows a twice-daily renewal of water in the lagoon, which is essential for regulating the high salt content. The low content of sediment in total organic carbon, reflect the low organic matter production of the mangrove because it is a young and stunted mangrove. Diagenetic processes are anaerobic and mostly in the top 10 cm of the sediment, on the recent deposit. The contribution of young mangroves, like Somone, in the carbon storage process, is low. The lagoonal-estuarine ecosystem of the Somone is fragile and highly reactive and his evolution is fast and linked to the cumulative effects of natural and anthropogenic factors.Située sur la Petite Côte du Sénégal, la Somone est une petite rivière côtière qui se jette dans l'océan atlantique par un écosystème laguno-estuarien à régime microtidal. Aujourd'hui, les apports du bassin versant sont inexistants du fait de la combinaison de plusieurs facteurs dont le barrage de Bandia. Les seuls apports en eau douce se font par les précipitations et la nappe. Le système laguno-estuarien de la Somone est caractérisé par un fonctionnement hydrologique inverse où les influences marines prédominent. La mangrove, à dominance de Rhizophora, est l'unité caractéristique de ce système côtier. L'évolution diachronique sur 60 ans montre une modification importante de tous les faciès, internes et externes, de l'écosystème. La mobilité de la flèche sableuse d'embouchure, qui s'est traduite par deux comblements en 1967-1969 puis en 1987, est liée à des variations climatiques et météorologiques. L'évolution régressive des surfaces de mangrove, entre 1954 et 1989, est le résultat de l'effet conjugué de ces périodes de comblements, de la sécheresse et des usages traditionnels de la mangrove. La restauration de la mangrove est essentiellement due aux politiques de reboisement administrées dans les années 2000. L'évolution annuelle et saisonnière montre que le remaniement interne est le processus hydro-sédimentaire dominant. Le taux de sédimentation moyen des vasières est de 2 à 3 mm/an. La dynamique de la flèche sableuse à l'embouchure de la Somone joue un rôle fondamental sur l'évolution et la qualité des faciès internes, notamment la mangrove. L'ouverture permanente de l'embouchure permet un renouvellement biquotidien des eaux dans le système laguno-estuarien, essentiel pour réguler les fortes teneurs en sels. Les faibles teneurs des sédiments en carbone organique total, témoignent de la faible production de la mangrove en matière organique car il s'agit d'une mangrove jeune et de forme rabougrie. Les processus diagénétiques se font en anaérobiose et essentiellement dans les 10 premiers cm du sédiment, sur du dépôt récent. La contribution des mangroves jeunes, comme celles de la Somone, au processus de stockage du carbone organique est faible. L'écosystème laguno-estuarien de la Somone est un système fragile et très réactif dont l'évolution, à l'échelle humaine, est rapide et liée à des effets cumulés de facteurs naturels et anthropiques