Dynamiques des paysages régionaux en zone cotonnière du Mali

International audienc

Expanding Research Capacity in Sub-Saharan Africa Through Informatics, Bioinformatics, and Data Science Training Programs in Mali

Bioinformatics and data science research have boundless potential across Africa due to its high levels of genetic diversity and disproportionate burden of infectious diseases, including malaria, tuberculosis, HIV and AIDS, Ebola virus disease, and Lassa fever. This work lays out an incremental approach for reaching underserved countries in bioinformatics and data science research through a progression of capacity building, training, and research efforts. Two global health informatics training programs sponsored by the Fogarty International Center (FIC) were carried out at the University of Sciences, Techniques and Technologies of Bamako, Mali (USTTB) between 1999 and 2011. Together with capacity building efforts through the West Africa International Centers of Excellence in Malaria Research (ICEMR), this progress laid the groundwork for a bioinformatics and data science training program launched at USTTB as part of the Human Heredity and Health in Africa (H3Africa) initiative. Prior to the global health informatics training, its trainees published first or second authorship and third or higher authorship manuscripts at rates of 0.40 and 0.10 per year, respectively. Following the training, these rates increased to 0.70 and 1.23 per year, respectively, which was a statistically significant increase (p < 0.001). The bioinformatics and data science training program at USTTB commenced in 2017 focusing on student, faculty, and curriculum tiers of enhancement. The program’s sustainable measures included institutional support for core elements, university tuition and fees, resource sharing and coordination with local research projects and companion training programs, increased student and faculty publication rates, and increased research proposal submissions. Challenges reliance of high-speed bandwidth availability on short-term funding, lack of a discounted software portal for basic software applications, protracted application processes for United States visas, lack of industry job positions, and low publication rates in the areas of bioinformatics and data science. Long-term, incremental processes are necessary for engaging historically underserved countries in bioinformatics and data science research. The multi-tiered enhancement approach laid out here provides a platform for generating bioinformatics and data science technicians, teachers, researchers, and program managers. Increased literature on bioinformatics and data science training approaches and progress is needed to provide a framework for establishing benchmarks on the topics

Subclinical Cardiac Dysfunction Is Associated With Extracardiac Organ Damages

Background: Several studies conducted in America or Europe have described major cardiac remodeling and diastolic dysfunction in patients with sickle cell disease (SCD). We aimed at assessing cardiac involvement in SCD in sub-Saharan Africa where SCD is the most prevalent.Methods: In Cameroon, Mali and Senegal, SCD patients and healthy controls of the CADRE study underwent transthoracic echocardiography if aged ≥10 years. The comparison of clinical and echocardiographic features between patients and controls, and the associations between echocardiographic features and the vascular complications of SCD were assessed.Results: 612 SCD patients (483 SS or Sβ0, 99 SC, and 19 Sβ+) and 149 controls were included. The prevalence of dyspnea and congestive heart failure was low and did not differ significantly between patients and controls. While left ventricular ejection fraction did not differ between controls and patients, left and right cardiac chambers were homogeneously more dilated and hypertrophic in patients compared to controls and systemic vascular resistances were lower (p < 0.001 for all comparisons). Three hundred and forty nine SCD patients had extra-cardiac organ damages (stroke, leg ulcer, priapism, microalbuminuria or osteonecrosis). Increased left ventricular mass index, cardiac dilatation, cardiac output, and decreased systemic vascular resistances were associated with a history of at least one SCD-related organ damage after adjustment for confounders.Conclusions: Cardiac dilatation, cardiac output, left ventricular hypertrophy, and systemic vascular resistance are associated with extracardiac SCD complications in patients from sub-Saharan Africa despite a low prevalence of clinical heart failure. The prognostic value of cardiac subclinical involvement in SCD patients deserves further studies

Developpement d’un système radar GPR à huit voies d’émission/réception

Encadré par Nicolas Fortin

Measurements of on-board antenna radiation patterns on the ground

La détermination du diagramme de rayonnement d’une antenne installée sur un porteur est indispensable pour la validation des systèmes RF auxquels sont associées ces antennes. Lorsque l’antenne est placée sur le porteur, la structure rayonnante est formée par l’antenne et le porteur. Le diagramme doit être déterminé à grande distance de la source dans la zone de champ lointain. Suivant la fréquence de travail et la taille de la source rayonnante, cette distance peut être grande. Elle est par exemple de l’ordre 85m lorsque l’on cherche à caractériser à 88MHz une source rayonnante de dimension maximale 12m. Actuellement, cette distance de champ lointain, est obtenue lors des essais en vol au cours desquels l’aéronef est à 80km de la station sol relevant le diagramme. Cette méthode de caractérisation n’est pas tenable à long terme, en raison de son coût et des temps de mesure. C’est pourquoi Airbus Helicopter veut mettre en œuvre une mesure au sol mais ce dernier perturbe grandement le rayonnement. La méthode de caractérisation retenue permet d’effectuer les mesures au sol dans un espace réduit et permet de s’affranchir de l’influence du sol. La méthode retenue repose sur la caractérisation en champ proche dans une géométrie cylindrique, associée à une technique de correction de diagramme de rayonnement basée sur la décomposition de modes. La mesure champ proche requiert l’acquisition des données de champ proche sur une surface cylindrique, puis un algorithme de transformation développé en environnent MATLAB effectue le passage en champ lointain. Le champ lointain est décomposé en modes cylindriques, puis un filtrage modal est appliqué pour s’affranchir de l’influence du sol.Aircraft antennas radiation pattern must be measured before radiofrequency systems deployment. When an antenna is on the aircraft, radiating structure is not only antenna element but it’s the set antenna and aircraft. Radiation pattern have to be determined at great distance from the radiating structure. This distance is located in area called far field area depending on the frequency of operation and the maximal size of the aircraft. For example, to measure an antenna on an aircraft of 12 m of long at 88 MHz; the far field area is at 85m.To get this distance, flight measurement is performed. During flight test, radiation pattern is determined by a ground station which is at 80 km of the aircraft. This method is very expensive and takes much time and causes serious delays on aircraft delivery. For these reasons Airbus Helicopters explores new innovative solution, like as radiation pattern measurement on the ground. The last one disturbs the radiation pattern. The proposed method allows to perform measurement in compact volume and cancel out the ground influence. Proposed solution is based on cylindrical near field measurement, and cylindrical modes decomposition. Near field data are scanned on cylinder surface, then an algorithm developed on MATLAB environment do near field to far field transformation. Cylindrical modes decomposition and modal filtering rid of ground reflections. Proposed solution has been validated numerically through comparison with electromagnetic simulator software results. Antenna measurement range in the laboratory has served to validate experimentally the proposed solution on a prototype in scale size

Dynamique de l'occupation du sol et trajectoire du couvert végétal autour de trois sites miniers du Sud Mali entre 1988 et 2019

Les opérations d'extraction d'or génèrent divers impacts sur l'environnement, qui doivent être mesurés spatialement. L'objectif de ce travail est de déterminer la dynamique d'occupation du sol et le changement du couvert végétal autour de trois sites miniers. Des images Landsat de deux périodes (pré-mine et actuelle) ont été utilisées. La méthode de classification par maximum de vraisemblance, couplée à un algorithme de détection de changement, a été utilisée pour déterminer l'étendue et les changements des classes d'occupation. Les valeurs du NDVI calculées à partir des images ont été réparties en six classes, cinq avec des niveaux de densité allant de très faible à très élevé et une négative sans végétation. Le test t de STUDENT a été utilisé pour comparer les valeurs du NDVI extraites de manière aléatoire sur 30 points. Les résultats montrent une forte dynamique des classes d'occupation du sol. Cette dynamique se caractérise par la conversion de l'espace de végétation dense en sol faiblement couvert, en surface agricole et en sol nu. Durant la même période, le couvert végétal a considérablement perdu de sa vitalité, signe d'une tendance à la dégradation. La comparaison des valeurs du NDVI extraites aléatoirement confirme cette perte de qualité de la végétation. Ce travail conclut que la végétation dans les sites miniers étudiés a subi une forte dégradation.Gold mining operations generate various environmental impacts that must be spatially measured. The objective of this research is to determine the dynamics of land use and the change in plant cover in three mining sites. Landsat images from two periods (pre-mine and current) were used. A maximum likelihood classification method coupled with a change detection algorithm was to determine the extent and changes of land use and land cover classes. The NDVI values calculated from the images were classified into six classes, five with density levels ranging from very low to very high and one negative without vegetation. STUDENT two samples t test was used to compare the NDVI values randomly extracted on 30 points. The results show strong dynamics of land cover classes. This dynamic is characterised by the conversion of dense vegetation space into slightly covered soil, agricultural area and bare soil. During the same period, the vegetation cover considerably lost its vitality indicating the degradation trend. The comparison of NDVI values extracted randomly confirms this loss of quality of the vegetation cover. This research concludes that the vegetation cover in the three mining sites has undergone severe degradation

Dynamiques des paysages régionaux en zone cotonnière du Mali

International audienc

Dynamiques des paysages régionaux en zone cotonnière du Mali

International audienc

Dynamique de l'occupation du sol et trajectoire du couvert végétal autour de trois sites miniers du Sud Mali entre 1988 et 2019

Gold mining operations generate various environmental impacts that must be spatially measured. The objective of this research is to determine the dynamics of land use and the change in plant cover in three mining sites. Landsat images from two periods (pre-mine and current) were used. A maximum likelihood classification method coupled with a change detection algorithm was to determine the extent and changes of land use and land cover classes. The NDVI values calculated from the images were classified into six classes, five with density levels ranging from very low to very high and one negative without vegetation. STUDENT two samples t test was used to compare the NDVI values randomly extracted on 30 points. The results show strong dynamics of land cover classes. This dynamic is characterised by the conversion of dense vegetation space into slightly covered soil, agricultural area and bare soil. During the same period, the vegetation cover considerably lost its vitality indicating the degradation trend. The comparison of NDVI values extracted randomly confirms this loss of quality of the vegetation cover. This research concludes that the vegetation cover in the three mining sites has undergone severe degradation

First Principle Calculation of Accurate Electronic and Related Properties of Zinc Blende Indium Arsenide (zb-InAs)

We carried out a density functional theory (DFT) study of the electronic and related properties of zinc blende indium arsenide (zb-InAs). These related properties include the total and partial densities of states and electron and hole effective masses. We utilized the local density approximation (LDA) potential of Ceperley and Alder. Instead of the conventional practice of performing self-consistent calculations with a single basis set, albeit judiciously selected, we do several self-consistent calculations with successively augmented basis sets to search for and reach the ground state of the material. As such, our calculations strictly adhere to the conditions of validity of DFT and the results are fully supported by the theory, which explains the agreement between our findings and corresponding, experimental results. Indeed, unlike some 21 previous ab initio DFT calculations that reported zb-InAs band gaps that are negative or zero, we found the room temperature measured value of 0.360 eV. It is a clear achievement to reproduce not only the locations of the peaks in the valence band density of states, but also the measured values of the electron and hole effective masses. This agreement with experimental results underscores not only the correct description of the band gap, but also of the overall structure of the bands, including their curvatures in the vicinities of the conduction band minimum (CBM) and of the valence band maximum (VBM)