Simple scaling of extreme precipitation regime in Senegal

Extreme precipitation exhibits high temporal and spatial variability, and understanding this variability is crucial for designing hydraulic infrastructures and assessing the impacts of natural risks such as floods and droughts. The Simple Scaling (SS) model, which describes the dependence of extreme rainfall statistics on timescales, is used to estimate Intensity Duration Frequency (IDF) curves. This study aims to evaluate the validity of the Simple Scaling (SS) hypothesis for 14 rain gauges in Senegal and explore the existence of breaks in temporal scaling regimes (transition regimes). For the analysis of extreme characteristics, we considered the Annual Maximum Series (AMS) of precipitation in sub-hourly and supra-daily durations ranging from 10 min to 7 days. The empirical validation of the SS models was confirmed for the majority of the scaling intervals. We identified two scaling breaks, indicating the presence of three scaling regimes: short durations (SD), intermediate durations (ID), and long durations (LD). The spatial variation of scaling exponents reveals the existence of different scaling regimes across Senegal. The results are valuable for modeling the spatial distribution of scaling exponents, which can aid in characterizing IDF curves at ungauged locations

Amas et sites coquilliers du delta du Saloum (Sénégal) : Passé et présent

International audienceThe three main branches of the Saloum delta: the Saloum in the north (110 km), the Diombos (30 km) and the Bandiala in the south (18 km) are joined by numerous small channels, locally called “bolons”. They create many islands that are bordered by dense mangrove and comprise three ecological zones: maritime, amphibious and continental. The delta comprises an area of around 500,000 ha and is inhabited by human communities that have been involved in maritime activities for well over two millennia. These include the exploitation of shellfish including the bivalves oyster, Crassostrea gasar, and cockle (Arca senilis) as well as the gastropods “Yett” (Cymbium spp.) and “Touffa” (Murex spp., Thais spp.), and the cuttlefish (Sepia officinalis), all of which proliferate in the Delta. Artificial shell mounds comprising bivalves and gastropods provide evidence for a human presence in the Delta for well over 2000 years. In some cases, the shell mounds have also been reused as burial grounds and contain many remains of the ancient fisher-collector inhabitants. The Saloum delta is: (1) an exceptional archaeological landscape with many hundreds of sites, and several periods of excavation, including 1939 (J. de Saint-Seine, M. Yvetot, T. Monod), 1951-1956 (H. Bessac, R. Mauny, G. Thilmans and C. Descamps), in 2000 (H. Bocoum, A. Camara, C. Descamps, E. Dioh, M. Gueye, A.A. Seck, G. Thilmans); (2) an archaeological heritage comprising shell mounds which support many baobab trees (Adonsonia digitata). In some cases, these trees become “sacred forests or woods” where ritual activities take place near modern villages; (3) a rich natural heritage containing shell mounds that have become refuges for wildlife especially birds, and flora…; (4) a cultural landscape comprising enduring traditions that are thousands of years old, based on shellfish harvesting and fishing, in a fragile natural environment of great biodiversity. It is one of the few places in the world where traditional shellfishing still survives. Researchers from Cheikh Anta Diop University in Dakar (A. Camara, E. Dioh, M. Guèye, M. Sall) and a team from the Autonomous University of Barcelona (UAB) (K. Hardy, R. Piqué, J. Marti) have been conducting ethnoarchaeological research on the Atlantic coast and the Gokehor bolon since 2010. The focus of the work is to document the distribution of the archaeological shell middens, conduct excavations, obtain samples for radiocarbon dating and record the cultural traditions associated with the current collection of shell middens. There are many features of this research that will be of interest to archaeologists, as well as contributing data in palaeoclimatology, archaeozoology and malacology in a delta inscribed on UNESCO's World Heritage List in 2011 on the basis of criteria III, IV and V.Les trois bras principaux du delta du Saloum : le Saloum au Nord (110 km), le Diombos (30 km) et le Bandiala au Sud (18 km) s’emboîtent par une infinité de petits canaux, appelés localement « bolons ». Ils créent de nombreuses îles bordées d’une mangrove dense qui font apparaître trois ensembles écologiques : un domaine maritime, un domaine insulaire et amphibie et un domaine continental. S’étendant sur environ 500 000 ha, le delta est habité par des communautés humaines qui y mènent, depuis plus de deux millénaires, des activités basées sur des ressources halieutiques dont une bonne partie concerne l’exploitation des mollusques : huîtres (Crassostrea gasar), les « Yett » (Cymbium spp.), les « Touffa » (Murex spp., Thais spp.) et les arches (Arca senilis) ainsi que les seiches (Sepia officinalis) qui prolifèrent dans ce biotope. Témoins d’activités dont les plus anciennes remontent dans le delta à plus de 2000 ans, des milliers d’amas de coquilles de bivalves et de gastéropodes constituent des vestiges archéologiques. Ces restes de consommation ont été aussi réutilisés comme éléments de construction de nécropoles, de tumulus funéraires par d’anciens pêcheurs-collecteurs. Le delta du Saloum est : (1) un paysage archéologique exceptionnel constitué de centaines de sites dont certains ont fait l’objet de fouilles en 1939 (J. de Saint-Seine, M. Yvetot, T. Monod), en 1951-1956 (H. Bessac, R. Mauny, J. Figuie), en 1971-1973 (G. Thilmans et C. Descamps), en 2000 (H. Bocoum, A. Camara, C. Descamps, E. Dioh, M. Guèye, A.A. Seck, G. Thilmans) ; (2) un patrimoine archéologique réutilisé par les populations d’aujourd’hui pour leurs espaces peuplés de baobabs (Adonsonia digitata) comme des « forêts ou bois sacrés » pour des libations et des sacrifices à faible distance des villages actuels ; (3) un patrimoine naturel avec des amas devenus des niches, des refuges pour la faune en particulier les oiseaux et la flore ; (4) un paysage culturel d’une tradition millénaire toujours vivante privilégiant un mode de vie basé sur la cueillette des coquillages et sur la pêche, dans un milieu naturel fragile d’une grande biodiversité et l’un des rares endroits au monde où les pratiques de collecte des coquillages survivent. Des chercheurs de l’Université Cheikh Anta Diop de Dakar (A. Camara, E. Dioh, M. Guèye, M. Sall) en collaboration avec une équipe de l’Université Autonome de Barcelone (K. Hardy, R. Piqué, J. Marti) mènent depuis 2010 des recherches ethnoarchéologiques dans la bordure atlantique et du bolon de Gokehor pour compléter les inventaires, les fouilles, les datations, les traditions culturelles associées de près ou de loin à la collecte actuelle des coquillages. Les intérêts de ces recherches sont multiples pour les informations archéologiques, paléoclimatiques, archéozoologiques, malacologiques dans un delta inscrit en 2011 sur la Liste du patrimoine mondial de l’UNESCO sur la base des critères III, IV et V

Update on the Assirik Chimpanzee (Pan troglodytes verus) Population in Niokolo Koba National Park, Senegal

The Assirik, Senegal chimpanzee population was studied extensively by McGrew and colleagues in the Stirling African Primate Project (SAPP) in the late 1970s1 and surveyed by the Miami Assirik Pan Project (MAPP) in 20002. These chimpanzees (thought to represent a single community3), within the Niokolo Koba National Park (or Parc National du Niokolo Koba, PNNK), remain the only protected population in the country, with most of Senegal’s chimpanzees living in unprotected areas4. In 2012, the Iowa State Assirik Primate Project (ISAPP) surveyed Assirik and outlying areas in the PNNK to assess chimpanzee density and to explore the possibility of establishing a research program there in collaboration with the National Parks Department of Senegal and University of Cheikh Anta Diop in Dakar. One objective in this study was to resurvey the Assirik area in order to compare our results to data collected in 2000.This is an article from PAN Africa News 19 (2012): 8. Posted with permission.</p

Partnership for Research on Ebola VACcination (PREVAC): protocol of a randomized, double-blind, placebo-controlled phase 2 clinical trial evaluating three vaccine strategies against Ebola in healthy volunteers in four West African countries

International audienceAbstract Introduction The Ebola virus disease (EVD) outbreak in 2014–2016 in West Africa was the largest on record and provided an opportunity for large clinical trials and accelerated efforts to develop an effective and safe preventative vaccine. Multiple questions regarding the safety, immunogenicity, and efficacy of EVD vaccines remain unanswered. To address these gaps in the evidence base, the Partnership for Research on Ebola Vaccines (PREVAC) trial was designed. This paper describes the design, methods, and baseline results of the PREVAC trial and discusses challenges that led to different protocol amendments. Methods This is a randomized, double-blind, placebo-controlled phase 2 clinical trial of three vaccine strategies against the Ebola virus in healthy volunteers 1 year of age and above. The three vaccine strategies being studied are the rVSVΔG-ZEBOV-GP vaccine, with and without a booster dose at 56 days, and the Ad26.ZEBOV,MVA-FN-Filo vaccine regimen with Ad26.ZEBOV given as the first dose and the MVA-FN-Filo vaccination given 56 days later. There have been 4 versions of the protocol with those enrolled in Version 4.0 comprising the primary analysis cohort. The primary endpoint is based on the antibody titer against the Ebola virus surface glycoprotein measured 12 months following the final injection. Results From April 2017 to December 2018, a total of 5002 volunteers were screened and 4789 enrolled. Participants were enrolled at 6 sites in four countries (Guinea, Liberia, Sierra Leone, and Mali). Of the 4789 participants, 2560 (53%) were adults and 2229 (47%) were children. Those < 18 years of age included 549 (12%) aged 1 to 4 years, 750 (16%) 5 to 11 years, and 930 (19%) aged 12–17 years. At baseline, the median (25th, 75th percentile) antibody titer to Ebola virus glycoprotein for 1090 participants was 72 (50, 116) EU/mL. Discussion The PREVAC trial is evaluating—placebo-controlled—two promising Ebola candidate vaccines in advanced stages of development. The results will address unanswered questions related to short- and long-term safety and immunogenicity for three vaccine strategies in adults and children. Trial registration ClinicalTrials.gov NCT02876328 . Registered on 23 August 2016