Reemergence of Sylvatic Dengue Virus in Southern Senegal, 2021

As part of the syndromic surveillance of fever in Senegal, the virology department at Institut Pasteur de Dakar (IPD) in collaboration with the Epidemiology Unit and the Senegalese Ministry of Health conducted syndromic surveillance of fever in Senegal. Sample are from all suspected arboviral infections patients attending any of the sentinel sites. Collected blood samples were sent on a weekly basis at WHOCC for arboviruses and hemorrhagic fever viruses for screening of seven medically important arboviruses, including dengue virus (DENV). From January to December 2021, 2010 suspected cases were received among them 124 for confirmed to be DENV+ by RT-qPCR attempt of serotyping led to the detection of atypical DENV case from Sare Yoba area (Kolda region) which is unable to be correctly assigned to a serotype by the available tools (TIB Molbiol Modular Dx Dengue typing kit). Performed genome sequencing et phylogenetic analysis leads to the identification of a sylvatic DENV-2 strain closely related to a virus previously detected in Guinee-Bissau in 2009. This finding constitutes proof of the contemporary circulation of DENV-2 strain belonging to the sylvatic cycle in addition to well-known epidemic strains; this adds a piece of complexity to dengue management in Senegal. Alarmingly, it calls for improved genomic surveillance of DENV to know the genetic diversity of circulating strains in order to strengthen future vaccination policies

Evolutionary algorithms converge towards evolved biological photonic structures

Nature features a plethora of extraordinary photonic architectures that have been optimized through natural evolution in order to more efciently refect, absorb or scatter light. While numerical optimization is increasingly and successfully used in photonics, it has yet to replicate any of these complex naturally occurring structures. Using evolutionary algorithms inspired by natural evolution and performing particular optimizations (maximize refection for a given wavelength, for a broad range of wavelength or maximize the scattering of light), we have retrieved the most stereotypical natural photonic structures. Whether those structures are Bragg mirrors, chirped dielectric mirrors or the gratings on top of Morpho butterfy wings, our results indicate how such regular structures might have spontaneously emerged in nature and to which precise optical or fabrication constraints they respond. Comparing algorithms show that recombination between individuals, inspired by sexual reproduction, confers a clear advantage that can be linked to the fact that photonic structures are fundamentally modular: each part of the structure has a role which can be understood almost independently from the rest. Such an in silico evolution also suggests original and elegant solutions to practical problems, as illustrated by the design of counter-intuitive anti-refective coatings for solar cells

Evolution of Surface Hydrology in the Sahelo-Sudanian Strip: An Updated Review

In the West African Sahel, two paradoxical hydrological behaviors have occurred during the last five decades. The first paradox was observed during the 1968–1990s ‘Great Drought’ period, during which runoff significantly increased. The second paradox appeared during the subsequent period of rainfall recovery (i.e., since the 1990s), during which the runoff coefficient continued to increase despite the general re-greening of the Sahel. This paper reviews and synthesizes the literature on the drivers of these paradoxical behaviors, focusing on recent works in the West African Sahelo/Sudanian strip, and upscaling the hydrological processes through an analysis of recent data from two representative areas of this region. This paper helps better determine the respective roles played by Land Use/Land Cover Changes (LULCC), the evolution of rainfall intensity and the occurrence of extreme rainfall events in these hydrological paradoxes. Both the literature review and recent data converge in indicating that the first Sahelian hydrological paradox was mostly driven by LULCC, while the second paradox has been caused by both LULCC and climate evolution, mainly the recent increase in rainfall intensity

Optimisation des structures nanophotoniques pour le photovoltaïque

The present manuscript deals with the problem of the design in photonics, i.e. to determine which is the best way to assemble nanometric elements to reach a desired optical response. Different algorithms are tested. One algorithm in particular seems well adapted to this kind of problem, and allows to retrieve the most emblematic photonic structures which a present in nature on the tegument of insects or on the wings of butterflies. Applied to the case of an anti-reflective coating for a photovoltaic device, the algorithm has produced a particularly counter intuivite but efficient structure. This clearly demonstrates the potential of such an approach.Ce manuscrit s'attache au problème du design en photonique, à savoir déterminer la meilleure façon d'agencer des éléments nanométriques pour obtenir la réponse optique que l'on désire. Différents algorithmes sont testés. Un algorithme en particulier semble adapté à ce type de problème, et permet de retrouver des structures photoniques présentes dans la nature sur les carapaces de certains insectes ou les ailes de certains papillons. Appliqué à l'anti-reflet d'une cellule photovoltaïque, l'algorithme a permis de trouver une structure contre-intuitive mais particulièrement efficace, ce qui montre tout le potentiel de cette technique

Optimization of nanophotonic structures for photovoltaics

Ce manuscrit s'attache au problème du design en photonique, à savoir déterminer la meilleure façon d'agencer des éléments nanométriques pour obtenir la réponse optique que l'on désire. Différents algorithmes sont testés. Un algorithme en particulier semble adapté à ce type de problème, et permet de retrouver des structures photoniques présentes dans la nature sur les carapaces de certains insectes ou les ailes de certains papillons. Appliqué à l'anti-reflet d'une cellule photovoltaïque, l'algorithme a permis de trouver une structure contre-intuitive mais particulièrement efficace, ce qui montre tout le potentiel de cette technique.The present manuscript deals with the problem of the design in photonics, i.e. to determine which is the best way to assemble nanometric elements to reach a desired optical response. Different algorithms are tested. One algorithm in particular seems well adapted to this kind of problem, and allows to retrieve the most emblematic photonic structures which a present in nature on the tegument of insects or on the wings of butterflies. Applied to the case of an anti-reflective coating for a photovoltaic device, the algorithm has produced a particularly counter intuivite but efficient structure. This clearly demonstrates the potential of such an approach

Evolutionary optimization of nanophotonic multilayered structures

International audienceWe apply optimization algorithms inspired by evolution photonic structures. Trying to maximize the reflection coefficient of a multilayered structure systematically leads to the famous Bragg mirror. This shows it is an optimal structure and explains why it is often found in nature. Genetic algorithm Genetic/evolutionary algorithms are optimization algorithms directly inspired by evolution. They use a process of selecting structures (here each structure will be called an "individual") best suited to what is desired. A cost function is defined for this purpose. The lower it is, the more the structure/individual is considered adapted, and the higher are its chance to "survive". • We take a starting population that is randomly generated. • The next generation is produced using different ways • A part of the previous generation is selected and kept-the more fit the individuals, the higher their chances to be kept. • The rest of the next generation is obtained combining two parents that have been selected in the previous generation because they are adapted to our criteria. • The best individual is always kept, as a reference

Etude et optimisation d'un Système Hybride Photovoltaïque-Eolien à Telico Mamou

International audienceThis work is a contribution to the study of hybrid photovoltaic and wind power conversion systems in Telico to find a sustainable solution to the IST- Mamou a constant energy without load shedding.In this study, we collected the energy needs of the Institut Supérieur de Technologie de Mamou and the meteorological data of Mamou. Then these data were introduced and analyzed by the HOMER software. This analysis shows that the wind potential is low while the solar potential seems to be more satisfactory, we obtained a load coverage provided by 386 photovoltaic modules of 260 Wp each and 5 wind generators of 7.5 kW per unit.The consumption profile adopted in this study is 577 kWh/dr with a maximum power 65 kW. This hourly energy distribution is considered identical for all days of the academic year and corresponds to the consumption profile of IST-Mamou. Moreover, we note that not only the load is largely covered, but also a surplus of energy production is noticed during the vacation months (July, August, and September).From all the results obtained in this study, it appears that the combination of the two renewable energy sources (solar and wind) is promising and advantageous for the continuous and uninterrupted production of energy for the total coverage of the energy needs of IST-Mamou.Keywords: hybrid system, photovoltaic, wind turbine, optimization.Ce présent travail constitue une contribution à l’étude des systèmes de conversion d’énergie électrique hybride photovoltaïque et éolienne à Telico afin de trouver une solution durable à l’IST- Mamou une énergie constante sans délestage.Dans cette étude, nous avons recueilli les besoins énergétiques de l’Institut Supérieur de Technologie de Mamou ainsi que les données météorologiques de Mamou. Ensuite ces données ont été introduites et analysées par le logiciel HOMER. Cette analyse montre que le potentiel éolien étant faible alors que le potentiel solaire semble plus satisfaisant, nous avons obtenu une couverture de charge assurée par 386 modules photovoltaïques de 260 Wc chacun et 5 aérogénérateurs de 7,5 kW par unité.Le profil de consommation adopté dans cette étude est de 577 kWh/jr avec une puissance maximale 65 kW. Cette distribution énergétique horaire est considérée identique pour tous les jours de l’année universitaire et correspond au profil de consommation de L’IST-Mamou. Par ailleurs, nous constatons que non seulement la charge est largement couverte, mais aussi un surplus de production d’énergie est remarqué pendant les mois de vacances (juillet, aout et septembre).A l’issus de l’ensemble des résultats obtenus dans cette étude, il ressort que la combinaison des deux sources d’énergies renouvelables (solaire et éolienne) est prometteuse et avantageuse pour la production continue et sans interruption d’énergie pour la couverture totale du besoin énergétique de l’IST-Mamou.Mots clés : système hybride, photovoltaïque, éolienne, optimisation