Reconstructing Late Holocene sea level change and impacts on early settlements in the Lofoten Islands, Norway

This study investigates the isolation sequence of several coastal lakes in the Lofoten Islands, northern Norway to understand how relative sea level has changed during the Late Holocene. I use established methods to assess changes in marine influence over the course of the lake records. Three cores ranging from 47 to 174 cm and spanning portions of the last 8000 cal yr BP were analyzed. I measured bulk density, bulk organic matter properties, and elemental profiles from scanning X-ray fluorescence. These characteristics of the sediment reflect detailed changes in salinity and water column conditions as the lakes became isolated. Three distinct lithostratgiraphic units were identified in Inner Borgpollen and represent an open marine phase where the basins were continually inundated marine water (3500 – 1600 cal yr BP), a brackish phase characterized by intermittent marine influence (1600 – 600 cal yr BP), and a tidal phase characterized by restricted marine influence (600 cal yr BP to present). The timing of these phases generally corresponds with previous interpretations of the local relative sea-level history and these records capture sea-level regression during the late Holocene which coincided with human settlements. As a result, changing salinity conditions due to the isolation process may explain the settlement patterns of early human populations between 1600 and 600 cal yr BP

Analyse de la règle de Taylor dans l’UEMOA : une décomposition de stress tests en période de chocs économiques

The aim of this article is to assess the applicability of the Taylor rule in the context of the West African Economic and Monetary Union (WAEMU), which comprises eight low-income countries using the CFA franc. The methodology of the study consists of calculating the interest rates resulting from the Taylor rule using aggregate and national data, and then analysing the differences between these rates. By examining the differences between the resulting interest rates, the study aims to understand the structural factors influencing the monetary policies of WAEMU countries and proposes solutions for reducing existing disparities. The results of the study show that most of the economic stress in the WAEMU zone comes from inflation. Analysis of the period from 1985Q1 to 2013Q4 shows that inflation is the main factor of economic stress in the zone studied. However, after the implementation of the Pact, WAEMU economies put more emphasis on output stress than on inflation stress. The weighting coefficients used in the analysis reveal a persistence of production-related stress. These results suggest that the specific output of the WAEMU economies is not strongly correlated with the average for the zone, despite relatively small inflation losses. In sum, this study uses the Taylor rule to evaluate monetary policy in the WAEMU and analyses the resulting interest rate differentials. The results highlight the importance of taking into account structural factors and economic disparities specific to each member country when implementing common monetary policies. These findings provide valuable information for policymakers and investors in the zone, with a view to promoting more balanced and sustainable economic growth.   Key words: Taylor rule, West African Economic and Monetary Union (WAEMU), monetary policy, interest rates, inflation, growth, stress test. JEL Classification: F22 Paper type: Empirical research.Cet article a pour objectif d'évaluer l'applicabilité de la règle de Taylor dans le contexte de l'Union économique et monétaire ouest-africaine (UEMOA), qui regroupe huit pays à faible revenu utilisant le franc CFA. La méthodologie de l'étude consiste à calculer les taux d'intérêt résultants de la règle de Taylor en utilisant des données agrégées et nationales, puis à analyser les écarts entre ces taux. En examinant les écarts entre les taux d'intérêt résultants, l'étude vise à comprendre les facteurs structurels qui influencent les politiques monétaires des pays de l'UEMOA et propose des solutions pour réduire les disparités existantes. Les résultats de l'étude mettent en évidence que la majeure partie du stress économique dans la zone de l'UEMOA provient de l'inflation. L'analyse de la période allant de 1985Q1 à 2013Q4 montre que l'inflation est le principal facteur de contrainte économique dans la zone étudiée. Cependant, après la mise en œuvre du Pacte, les économies de l'UEMOA accordent davantage d'importance au stress lié à la production par rapport au stress lié à l'inflation. Les coefficients de pondération utilisés dans l'analyse révèlent une persistance du stress lié à la production. Ces résultats suggèrent que les productions spécifiques des économies de l'UEMOA ne sont pas fortement corrélées à la moyenne de la zone, malgré des pertes d'inflation relativement faibles. En somme, cette étude utilise la règle de Taylor pour évaluer la politique monétaire de l'UEMOA et analyse les écarts entre les taux d'intérêt résultants. Les résultats soulignent l'importance de prendre en compte les facteurs structurels et les disparités économiques spécifiques à chaque pays membre lors de la mise en œuvre de politiques monétaires communes. Ces conclusions fournissent des informations précieuses aux décideurs politiques et aux investisseurs de la zone, afin de promouvoir une croissance économique plus équilibrée et durable.   Mots clé : Règle de Taylor, Union économique et monétaire ouest-africaine (UEMOA), politique monétaire, taux d'intérêt, inflation, croissance, stress test. Classification JEL : F22 Type de l’article : Recherche empiriqu

Advances and Perspectives in the Study of the Malaria Mosquito Anopheles funestus

International audienc

An outbreed mouse model of yellow fever for study of pathogenesis and development of vaccines and therapeutics

Yellow fever (YF) is a mosquito-borne viral disease that is endemic in several African and South American countries. YF virus (YFV) causes subclinical infections with mild and non-specific symptoms, to severe, potentially lethal illness with jaundice, hemorrhage, and renal failure. Despite the existence of safe and efficient vaccines, epidemics continue to occur, mostly in Africa where the burden of YF is estimated to represent 1.7 million annual cases and up to 80,000 deaths per year. Moreover, emergence of YF has been reported in new, previously unaffected areas, because of the introduction of the mosquito vectors into these lands. There is no effective therapy against YFV infection but licensed vaccines are available, which are derivatives of a live attenuated strain that was first developed in 1937. These vaccines are currently being used in vaccination program in endemic countries and for travelers visiting these regions. They provide a long-lasting immunity against all the known genotypes of YFV. Although very rare, there are reports of serious adverse effects associated with these vaccines. One major drawback of YF vaccines is their preparation that is based on culture on embryonated eggs, a fastidious and lengthy process that limits the capacity to produce high volumes of stocks needed to respond to recurring epidemics and to prepare for a potential major outbreak. An effective therapy and new types of vaccine that can support rapid scale up is needed for efficient management of YF in the future. The best available animal models to enable these endeavors are currently non-human primates (NHP) in which YF cause a disease similar to human infection of YF. However, the cost of NHP studies is a limit to preclinical studies, in particular in the most affected areas of the globe. There are a few mouse models of YF. However, these models consist of genetically-deficient rodents that are not best suited to replicate the disease and to accurately evaluate new vaccines or therapies. We have developed a mouse model of YFV infection based on the Swiss Webster outbred strain. We have tested several epidemics isolates and identified strains that, when administrated by the intraperitoneal route, caused an acute infection leading to death. Interestingly, these YFV strains are lethal only when prepared from mouse organs and not when cultured on cell lines. We used this model to test the efficacy of the 17D YFV vaccine strain in protecting mice against lethal challenge showing that the model can be used to evaluate new YF vaccines and therapies

Contributions of Aeromagnetic and Field Surveys to Geological and Structural Mapping of Pan-African Province of South Maradi, Southern Niger

This study focused on geological and structural mapping of Pan-African Province of South Maradi by using the aeromagnetic and filed surveys. The study zone corresponds to the northern part of the Benin-Nigerian Shield, belonging to the Pan-African mobile zone in the East of West African Craton. Previous geological work dates from the 1970s and limited to the summary geological map. According to this work, basement formations crop out discontinuously and are not subject by a structural study. In addition, the use of this map reveals a problem of correlation between the geological contours described on the existing map and those observed in the field. A combined analysis of aeromagnetic and field data led to complete then correct the petrographic and structural gap existing in the previous summary geological map since 1970s, which allowed to produce a new geological and structural map of studied zone (South Maradi Pan-African province). Petrographic and structural analysis of this new map shows that the spatial distribution of geological formations is characterized by the alternating Schist Belts and mylonitic gneiss Shear zones associated with migmatites panels and granitoïd intrusions. Thus, the different petrographic facies mapped are represented by schists-micaschist, mylonitic gneiss, migmatitic gneiss and intrusive porphyric granites. Previous data revealed a petrographic and structural continuity between South Maradi Pan-African formations with those of contiguous Pan-African province of North Nigeria

Caractérisation de la déformation des dépôts oligocènes du Continental terminal 3 (Ct3) dans la région de Niamey (Bordure Orientale du Craton Ouest Africain, Bassin des Iullemmeden)

Cette étude porte sur la détermination des phases de déformations affectant les dépôts oligocènes du Ct3, correspondant aux derniers dépôts de comblement du bassin des Iullemmeden dans la région de Niamey (Ouest, Niger). La méthodologie mise en œuvre est basée sur l’analyse microtectonique de terrain soutenue par des données cartographiques et de l’imagerie satellitaire. Les résultats de cette étude montrent que les dépôts oligocènes du Ct3 ont enregistré deux évènements majeurs de l’histoire tectonique de l’Afrique de l’Ouest au Cénozoïque : la distension oligocène et la phase compressive post-oligocène, d’âge présumée miocène. La phase distensive oligocène orientée ~N50° à ~N80° serait étroitement contrôlée par la dynamique mantellique prévalant à cette époque, qui confère une structuration en dômes et bassins à l’Afrique de l’Ouest. Ces mouvements mantelliques descendants, concomitant au dernier épisode de comblement du bassin des Iullemmeden, favoriseraient le rejeu en normal de la plupart des failles d’orientation NW-SE. La phase compressive ~N140°, présumée d’âge miocène, se serait produite dans un contexte régional marqué par la poursuitende la convergence Afrique-Europe. Au cours de cette phase compressive, les failles héritées ont été réactivées en décrochements soit senestres soit dextres en fonction de leur orientation par rapport à la direction de raccourcissement. The aim of this study is about the determination deformations phases that affect the Ct3 Oligocene deposits in the Niamey area (West, Niger), which correspond to the last deposits of the Iullemmeden basin. The methodology implemented is based on the microtectonic field investigation supported by cartographic data and satellite imagery analysis. The results of this study show that the Oligocene deposits of Ct3 recorded two major events of the West Africa tectonic history during Cenozoic period: the first one was Oligocene distension and the second was a post-Oligocene compressive phase, presumed to be Miocene in age. The Oligocene distensive phase oriented ~N50° to ~N80° would be closely controlled by the mantle dynamics prevailing at that time, which gave domes and basins structuring in West Africa. These downward mantle movements, concomitantly with the last episode of the Iullemmeden basin infilling, would favor the normal reactivation of the most NW-SE trending faults. The ~N140° compressive phase, presumed to be Miocene in age, would have occurred in a regional shortening context, which was marked by the continuation of the Africa-Europe convergence. During this compressive phase, the inherited structures such as faults were reactivated in either senestral or dextral strike-slip faults according to their orientation with the shortening direction

Impacts of Deep Water Structuring on Seabed Pollution Levels: Evidence from Radiogenic Isotopes (Pb-Sr-Nd) in Surface Sediments Along the Reykjanes Ridge (Southern Iceland)

Significant proportions of debris containing pollutants are present in remote and unknown areas of the deep seabed. Although identified amongst the top threats to marine ecosystem and human health, the mechanisms that particulate materials entered rapidly these deep ocean systems are still matter of debate. This study use depicting radiogenic isotopes (Sr, Nd, Pb) to question the relationship between the seabed sediment contamination levels and ambient stratification in the North Atlantic Ocean. On this basis, we studied sedimentary inputs and related mechanisms from more recent sequences collected at three locations representing different deep-sea hydrodynamics along the Reykjanes Ridge. Sm-Nd concentrations, as well as Sm-Nd-Sr-Pb isotopic compositions, were determined in digested and purified fraction of the sediment cores by Thermal Ionization Mass Spectrometry (TIMS). The Sm-Nd-Sr-Pb data simply reflect the scale of the perturbation of upper part (0-15 cm) of the sequences, which is much more pronounced in east flank than crossing and west bordering ridge areas. The Pb-Pb systematics show that the intensity of water mass mixing modulates degree of contamination and induced the modal transport of detrital components. As consequence of ambient stratification in this region, two major transport processes of pollutant downwards to the sediments are proposed: (i) sediments entrainment in the eastern flank and over ridge axis primarily dominated by vertical flux of particulates controlled by repackage and dislocation by strong mechanical mixing; and (ii) in the west flank, advection of abyssal waters, due to well-stratified mixing layer, provides particulates from the NEADW1 and DSOW

Conjugaison de facteurs institutionnels, organisationnels et individuels comme déterminants des principes d’engagement RSE au Sénégal

La RSE est devenue un thème majeur dans la littérature en sciences de gestion. L’objet du présent article est de proposer de nouvelles voies théoriques et méthodologiques pour une meilleure compréhension de l’engagement RSE des entreprises. S’inspirant des travaux de Wood (1991, 2010), il propose un nouveau modèle d’engagement sociétal des entreprises incluant les travaux des néo-institutionnalistes institutionnelles de (Meyer et Rowan, 1977 ; Powell et DiMaggio, 1983), le principe de solidarité générationnelle issu des théories du développement durable et l’outil PRESOR de (Singhapakdi et al., 1996). La validation empirique a été effectuée en utilisant les Systèmes d’Équations Structurels, plus spécifiquement l’approche PLS PM (Partial Least Path Modeling) à l’aide d’un échantillon de 119 observations. Les résultats mettent en évidence le développement d’un nouvel outil de mesure fiable et valide pour évaluer les perceptions des acteurs sur l’engagement RSE au Sénégal et proposent une configuration de principes institutionnels, organisationnels et individuels comme déterminants

Refractory Hard Alloys Elaborated by Casting of Ternary (Co, Ni Fe)-30Cr-2.5 to 5 wt% C Compositions

International audienceThree series of ternary alloys of the {M-30Cr-xC}-type with M = Co, Ni or Fe and x ranging from 2.5 to 5 wt% were elaborated by casting. Their microstructure characterizations by XRD and SEM show that very high volume fractions in chromium carbides (even more than 50%) may be obtained in a metallic matrix by this way. However graphite may also appear in very low quantities in the carbon-richest alloys. The hardness increases with the carbon content (up to 1000 Hv30kg) but it may be a little lowered when graphite is also present. The results show that very hard alloys may be simply obtained by casting of rather cheap elements