AfriQA:Cross-lingual Open-Retrieval Question Answering for African Languages

African languages have far less in-language content available digitally, making it challenging for question answering systems to satisfy the information needs of users. Cross-lingual open-retrieval question answering (XOR QA) systems -- those that retrieve answer content from other languages while serving people in their native language -- offer a means of filling this gap. To this end, we create AfriQA, the first cross-lingual QA dataset with a focus on African languages. AfriQA includes 12,000+ XOR QA examples across 10 African languages. While previous datasets have focused primarily on languages where cross-lingual QA augments coverage from the target language, AfriQA focuses on languages where cross-lingual answer content is the only high-coverage source of answer content. Because of this, we argue that African languages are one of the most important and realistic use cases for XOR QA. Our experiments demonstrate the poor performance of automatic translation and multilingual retrieval methods. Overall, AfriQA proves challenging for state-of-the-art QA models. We hope that the dataset enables the development of more equitable QA technology

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

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

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

A Rare Cause of Obstructive Chronic Hydrocephalus in an Adult Patient: A Case Report of Fourth Ventricle\'s Foramina Idiopathic Stenosis

Background & Importance: Idiopathic stenosis of the foramina of Magendie and Luschka is a rare cause of obstructive hydrocephalus involving the fourth ventricle. Case Presentation: We reported the case of a 40-year-old woman who developed headaches and vertigo for several months and more recently gait disturbance. The CT scan showed quadri-ventricular hydrocephalus involving mainly the fourth ventricle with dilated lateral recesses. Craniocervical MRI confirmed hydrocephalus and also showed the brainstem and cerebellar tonsil herniation through the foramen magnum with hydromyelia and a hyperintense signal on T2 weighted MRI of cervical spinal cord. Biological analyses were normal. She underwent endoscopic third ventriculostomy (ETV). No complication was observed. The patient became asymptomatic during the weeks following the surgical procedure and remained stable at a mean follow-up interval of 20 months. Postoperative MR images demonstrated regression of the hydrocephalus; complete disappearance of brainstem and cerebellar tonsil herniation, hydromylia and the hyperintense signal on T2 weighted MRI of cervical spinal cord. Conclusion: This case confirms the existence of hydrocephalus caused by idiopathic fourth ventricle outflows obstruction in adult and the efficacy of ETV for this rare indication

Formation and Transport of a Saharan Dust Plume in Early Summer

This research studies the capability of the Weather Research and Forecasting model coupled with the Chemistry/Aerosol module (WRF-Chem) with and without parametrization to reproduce a dust storm, which was held on 27th June 2018 over Sahara region. The authors use satellite observations and ground-based measurements to evaluate the WRF-Chem simulations. The sensitivities of WRF-Chem Model are tested on the replication of haboob features with a tuned GOCART aerosol module. Comparisons of simulations with satellite and ground-based observations show that WRF-Chem is able to reproduce the Aerosol Optical Depth (AOD) distribution and associated changes of haboob in the meteorological fields with temperature drops of about 9 °C and wind gust 20 m·s–1. The WRF-Chem Convection-permitting model (CPM) shows strong 10-meter winds induced a large dust emission along the leading edge of a convective cold pool (LECCP). The CPM indicates heavy dust transported over the West African coast (16°W-10°W; 6°N-21°N) which has a potential for long-distance travel on 27th June between 1100 UTC and 1500 UTC. The daily precipitation is improved in the CPM with a spatial distribution similar to the GPM-IMERG precipitation and maximum rainfall located at the right place. As well as raising a large amount of dust, the haboob caused considerable damage along its route

Caractérisation de la flore phytoplanctonique dans l'Aire Marine Protégée (AMP) de Bamboung et de deux sites environnants (Sénégal)

Au Sénégal, peu d'études sur le plan planctonique ont été réalisées pour l'évaluation de l'efficacité des Aires Marines Protégées. Dans cette perspective, la caractérisation de la flore phytoplanctonique et sa distribution spatio-temporelle à l'intérieur et à l'extérieur de l'AMP de Bamboung a été réalisée en avril et en septembre 2016. Des prélèvements d'échantillons d'eau à l'aide d'un filet à plancton de 20 µm de mailles ainsi que des mesures de paramètres physico-chimiques ont été faits dans chaque station. L'analyse des données environnementales a montré l'existence d'uneffet intersaison avec des valeurs plus élevées en avril excepté la température. Par ailleurs, un effet d'inter-sites a été observé uniquement en septembre pour la température, la salinité, la conductivité et l'oxygène dissout.En termes de diversité phytoplanctonique, en avril, 49 espèces réparties dans5 classes ont été identifiées dans l'AMP contre 47espèces et 5 classes identifiées à Diomboss et 42 espèces et 5 classes à Sangako. En septembre, 57espèces réparties dans 5 classes ont été répertoriées dans l'AMP contre 54 espèces et 4 classes à Diomboss, et 51 espèces réparties dans 4 classes identifiées à Sangako. Les résultats seuls de la richesse spécifique du phytoplancton ne permettent pas d'apporter une contribution sur l'évaluation de l'efficacité de l'AMP de Bamboung