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For more than one century, Aedes species are supposed to be a reservoir in dengue, yellow fever, rift valley fever and west nile viruses transmission. In this article, we study an infinite dimension ordinary differential equations system that models arbovirus vertical transmission in \textit{Aedes} mosquito. Relying of the positive semigroup theory, we show that the model is well-posed and compute a threshold parameter known as the basic reproduction ratio $R0$. This parameter describes "the average rate of secondary new cases of infected adult females from emergences in a breeding habitat that are produced by an infected adult female via transovarial transmission during its lifetime." In addition, we prove that the solution of the model goes to zero asymptotically if R0 Depuis plus d'un siècle, certaines espèces Aedes sont supposées jouer un rôle de réservoir de virus dans les épidémies de la dengue, de la fièvre jaune, de la fièvre de la vallée du Rift et du Nil occidental. Dans cet article, nous étudions un système différentiel de dimension infinie décrivant la transmission verticale des arbovirus chez les moustiques Aedes. Grâce à la théorie des semi-groupes positifs, nous avons montré que le modèle est bien pos\'e et extrait un paramètre seuil appelé taux de reproduction de base R0. Ce paramètre R0 décrit " le taux moyen de cas secondaires d'infection des femelles adultes émergentes dans un habitat de reproduction à partir d'oeufs contaminés via la transmission transovarienne et pondus par une femelle adulte durant sa vie". De plus, nous avons démontré que la solution du modèle tend vers zéro quand t tend vers l'infini si R0

International audience; The capital structure of a company is not the result of chance; it is in principle the result of a decision to integrate a whole set of factors. Thus, in order to understand the diversity of debt behavior of companies listed on the BRVM, several factors must be taken into consideration. The main objective of this article is to verify the factors that can influence the financial structure of BRVM-listed firms and to analyze their influence. Our study focuses on a sample of 28 BRVM-listed firms over a period of 11 years (2009 to 2019), using panel data. Following an econometric study involving the methods of generalized least squares (fixed effect) and generalized method of moments (one-step), we tested the influence of traditional firm-related determinants and corporate governance determinants on leverage.The results reveal that most of the determinants explain the leverage behavior of firms listed on the BRVM. They show that the variables size, tangibility, cost of financing, tax savings not related to debt is significant and positively influence the level of debt, these results are explained by the trade-off theory. Unlike the variable profitability, the size of the board of directors which are significant and influence negatively the level of debt. These results confirm the predictions of the hierarchical preference theory.However, the variable growth opportunity, liquidity and power separation are not significant, i.e. they do not explain the debt behavior of our study sample.The results obtained from this research will help explain the financing policy of firms listed on the BRVM. In addition, they will be used by the managers of the companies to find some answers to their decisions concerning the policy of indebtedness.

Access to health services is a concern around the world. Different strategies were developed, but Africa’s rate remains the lowest. This article aims to contribute to the population's access to healthcare, and to assess the determinants of the use of mutual health insurance by the population of the Ziguinchor region in Senegal. Methods: The study is transversal and descriptive, carried out from July to August 2018. Through the quota method we defined the number of patients to be interviewed. Thus, by a geographic stratification according to the departments and a second-degree stratification taking into account the staff of the different hospital departments, 392 patients were selected. Results: 73% at the Regional Hospital Center and 27% at the Regional Peace Hospital. Response rate: 97%, women 60% and men 40%. The enrollment for women (24%) is slightly higher than that for men (21%). Socio-economic factors. The rate of adherence is the highest of for patients with university level, followed by high school; income: the highest rate for patients with a monthly income between 200,000 and 500,000 FCFA, followed by patients with an income monthly between 100,000 and 200,000 FCFA. Factors linked to the provision of care: the rate of Mutual Health Insurance adherence follows distances from patients' homes. Concerning the relation to satisfaction, education, distance and information are more determining than adherence rate. Recommendations: 1) State: actions on education and distance; 2) Sensitizing the population on mutual health insurance; 3) Urging healthcare providers to reduce waiting times and respect schedules as well as appointments., South Eastern European Journal of Public Health (SEEJPH), Special Volume No. 2, 2021: Announcing the Hideyo Noguchi Africa Prize (1st edition)

International audience; Les technologies de l'information et de la communication (TIC) ont favorisé un changement important dans la gestion et la capitalisation des données au sein des organisations. Cependant, le secteur public de la santé au Sénégal est en retard dans sa transformation digitale. En effet, de grandes quantités de données sont produites quotidiennement par les activités médicales telles que les consultations, les comptes rendus d’hospitalisation, les rapports d’analyse de laboratoire, les comptes rendus opératoires, etc. Ces données sont consignées dans des supports essentiellement textuels (registres), des images, des fichiers audio et vidéo dont le mode d’accès et d’exploitation se fait principalement de manière manuelle. Face à cette problématique, les systèmes d’information hospitaliers constituent aujourd’hui une solution incontournable pour la gestion électronique du dossier patient, l’amélioration de la prise en charge sanitaire et la rationalisation des ressources humaines et financières. Au cours de cette présentation, nous mettrons en évidence les défis à relever dans la gestion des données de notre système de santé. Nous parlerons de l’expérience du projet de mise en place d’un Système d’Information Médical National pour le Sénégal (SIMENS) et de ses perspectives sur l’amélioration de notre système de santé et la recherche biomédicale. Par ailleurs, compte tenu des nouvelles problématiques posées par la collecte et le stockage de données massives par nos plateformes en santé, nous présenterons les nouvelles pistes et résultats de recherche qui en découlent dont (1) la conception d’approches et d’outils de visualisation pour améliorer l’accès facile et rapide par le médecin à l’historique médicale des patients et (2) la proposition de modèles de prédiction des complications de certaines pathologies chroniques comme en cardiologie. A propos de SIMENS : Le projet SIMENS a pour objectif de développer un système d’information pour la gestion des activités et des données médicales et administratives des établissements sanitaires du Sénégal. Le projet a commencé depuis environ 10 ans et est aujourd’hui dans sa phase d’expérimentation en collaboration avec le Centre Hospitalier Régional de Saint-Louis (CHRSL). Le système a été conçu avec l’appui des médecins de l'UFR des Sciences de la Santé de l’Université Gaston Berger (UGB) de Saint-Louis pour une meilleure prise en compte des spécificités du système de santé du Sénégal. Le projet est porté par le Laboratoire d’Analyse Numérique et d’Informatique de l’UGB et l'Équipe Interdisciplinaire de Recherche en Informatique Médicale et en Technologies de l'Information et de la Communication pour l'Enseignement (IMTICE) de l’Université Alioune Diop de Bambey (UADB), avec la contribution scientifique du Laboratoire d'Informatique Médicale et d'Ingénierie des Connaissances en e-Santé (LIMICS). [Vidéo en ligne]

International audience; The aim of this paper is to analyze the dynamic evolution of six liquidity proxies ontime, and to find their causality with the French CAC 40 stock market index returns, overthe period from January 2007 to December 2018. For that, we use a vector autoregressiveapproach and the impulse response function, to do causality test between the CAC 40 index returns and six differents liquidity proxies. Empirical results suggest a significantshort-term relationship between the returns and the liquidity. As for Granger’s causalitytest, the results reveal that there is unidirectional causality running from equity returnsto liquidity.

International audience; Understanding how structural features influence effective thermal conductivity is an essential step towards the optimization of heterogeneous materials. Generally, thermal conductivity models link the internal structure to the effective thermal conductivity, with the volume fraction as the only parameter that takes into account the internal structure. Yet, the real internal structures of materials are often too complex to be accurately characterized by the volume fraction only. In this study, the influence of three parameters - the particle size, volume fraction, and thermal conductivity ratio of the constituents - on the effective thermal conductivity of concrete is evaluated. Two-point correlation and lineal path functions are used to characterize the internal structure generated by the Random Sequential Addition (RSA) model. A finite element model is developed to evaluate the effective thermal conductivity of concrete. The results demonstrate that the internal structure of concrete is dependent on the volume fraction of the inclusions, and also of the particle size. However, for volume fractions less than 20%, the effective thermal conductivity is dependent only of the volume fraction and thermal conductivity ratio of the constituents.

We establish in this paper the uniform-in-bandwidth consistency for general kernel-type estimators of regression. More precisely, we investigate the regression estimator based on copula representation. The asymptotic properties are driven by a U -statistic relying on the methods developed in Dony and Mason (2008).

Two important lines of research have shaped our understanding of the ability of communities to engage in collective action. The first proposes ethnic division as a key determinant, with more ethnically-heterogeneous countries having worse economic performance and fewer public goods. The second focuses on social capital as a major determinant of the ability to engage in collective action. We expect trust among community members, a widely-used measure of social capital, to be an important and positive determinant of school quality. Our work here aims to disentangle the relative effects of ethnic fractionalization and social capital on school quality. We instrument both social capital and ethnic fractionalization by using historical information on the settlement patterns of ethnic groups in Sub-Saharan Africa. Our empirical strategy is implemented by combining four datasets, including district-level Afrobarometer data, covering 16 Sub-Saharan countries. We find a large positive effect of trust on practical aspects of schooling, such as maintaining buildings or providing textbooks. In sharp contrast, ethnic fractionalization is found to have a very limited effect, if any. We propose a simple model of public-good provision that explores a channel by which social capital and ethnic division may (or may not) affect the provision of local public goods such as schools.

International audience; A new method was developed for determining trace amounts of pesticides, using an ultraviolet (UV) lamp to obtain photo-induced fluorescent (PIF) compounds, and then using laser excitation (LE) by a tunable source to excite and simultaneously characterize their fluorescence over a short acquisition time using an intensified charge-coupled device camera. This new UV-PIF-LE method was applied to determine isoproturon, oxadiazon, and fipronil in natural waters. This approach represents an improvement on the previously published direct laser photo-induced fluorescent (DL-PIF) approach that utilized the inclusion of a supplementary UV irradiation device in the experimental setup, permitting the separation of the formation and detection steps for the PIF analytes. This evolution improves the selectivity and increases the sensitivity while maintaining a short analysis time. The UV-PIF-LE method gave very good results with satisfactory analytical performance for the determination of the selected pesticides. This approach also demonstrated good reproducibility, with relative square deviation values between 3.3% and 6.3%, for spiked river water and seawater samples with detection limits in the ng mL−1 range.

International audience; In Senegal, tick-borne relapsing fever (TBRF) is a major cause of morbidity and a neglected public health problem. Borreliosis cases commonly detected in two villages led us to implement a borreliosis preventive control including cementing of floors in bedrooms and outbuildings attended by inhabitants to avoid human contacts with tick vectors. Epidemiological and medical monitoring of the TBRF incidence was carried out at Dielmo and Ndiop by testing the blood of febrile patients since 1990 and 1993, respectively. Intra-domiciliary habitat conditions were improved by cementing, coupled with accompanying measures, from March 2013 to September 2015. Application of this strategy was associated with a significant reduction of borreliosis incidence. This was more evident in Dielmo, dropping from 10.55 to 2.63 cases per 100 person-years (P < 0.001), than in Ndiop where it changed from 3.79 to 1.39 cases per 100 person-years (P < 0.001). Thirty-six cases of TBRF were estimated to be prevented at a cost of €526 per infection. The preventive control strategy was successful in Dielmo and Ndiop, being associated with decreased incidence by 89.8% and 81.5%, respectively, suggesting that TBRF may be widely decreased when the population is involved. Public health authorities or any development stakeholders should adopt this effective tool for promoting rural health through national prevention programs.

International audience; We derive an empirical poverty index containing most of those proposed in the literature. Then, we study its asymptotic behavior by using empirical processes theory. From the results obtained, we derive a Wald-type test for comparing a vector of theoretical poverty indices to a vector of reference indices. We study the test statistic under the null hypothesis of equality, fixed alternatives, and a sequence of local alternatives. A simulation experiment conducted shows that our test performs well for exponential and Pareto data.

Topics in topic modelling approaches are represented as a collection of weighted words. The labels for the topics, however, are not clearly defined and must be interpreted manually. Topic labelling proposes to automatically label the topics by leveraging a knowledge base or applying data mining and machine learning algorithms. We propose a naive topic labelling approach where we transform the labeling problem into selecting the best label for each word in the topic. The candidate labels are generated by querying a knowledge base using the top-N words of each topic. We construct a heterogeneous graph of topics, words, articles and candidate labels. To rank the candidate labels, we apply truth discovery algorithms on the graph. The performance evaluation using popular topic modelling datasets shows that the approach receives satisfactory accuracy.

This paper studies the complexity of query evaluation for databases whose relations are partially ordered; the problem commonly arises when combining or transforming ordered data from multiple sources. We focus on queries in a useful fragment of SQL, namely positive relational algebra with aggregates, whose bag semantics we extend to the partially ordered setting. Our semantics leads to the study of two main computational problems: the possibility and certainty of query answers. We show that these problems are respectively NP-complete and coNP-complete, but identify tractable cases depending on the query operators or input partial orders. We further introduce a duplicate elimination operator and study its effect on the complexity results., 55 pages, 56 references. Extended journal version of arXiv:1707.07222. Up to the stylesheet, page/environment numbering, and possible minor publisher-induced changes, this is the exact content of the journal paper that will appear in Theoretical Computer Science

International audience

To combine and query ordered data from multiple sources, one needs to handle uncertainty about the possible orderings. Examples of such "order-incomplete" data include integrated event sequences such as log entries, lists of properties (e.g., hotels and restaurants) ranked by an unknown function reflecting relevance or customer ratings, and documents edited concurrently with an uncertain order on edits. This paper introduces a query language for order-incomplete data, based on the positive relational algebra with order-aware accumulation. We use partial orders to represent order-incomplete data, and study possible and certain answers for queries in this context. We show that these problems are respectively NP-complete and coNP-complete, but identify many tractable cases depending on the query operators or input partial orders., This paper is the full version with appendices of the TIME'17 article. See also the upcoming journal version: arXiv:1801.06396. Important note: This version (version 2) removes some results because we found a bug in their proofs. See Appendix G for detailed explanations. The journal version also omits the affected results (and does not contain Appendix G)

Purpose This paper aims to focus on the design of algorithms and techniques for an effective set expansion. A tool that finds and extracts candidate sets of tuples from the World Wide Web was designed and implemented. For instance, when a given user provides , , as seeds, our system returns tuples composed of countries with their corresponding capital cities and currency names constructed from content extracted from Web pages retrieved. Design/methodology/approach The seeds are used to query a search engine and to retrieve relevant Web pages. The seeds are also used to infer wrappers from the retrieved pages. The wrappers, in turn, are used to extract candidates. The Web pages, wrappers, seeds and candidates, as well as their relationships, are vertices and edges of a heterogeneous graph. Several options for ranking candidates from PageRank to truth finding algorithms were evaluated and compared. Remarkably, all vertices are ranked, thus providing an integrated approach to not only answer direct set expansion questions but also find the most relevant pages to expand a given set of seeds. Findings The experimental results show that leveraging the truth finding algorithm can indeed improve the level of confidence in the extracted candidates and the sources. Originality/value Current approaches on set expansion mostly support sets of atomic data expansion. This idea can be extended to the sets of tuples and extract relation instances from the Web given a handful set of tuple seeds. A truth finding algorithm is also incorporated into the approach and it is shown that it can improve the confidence level in the ranking of both candidates and sources in set of tuples expansion.

The collection and exploitation of ratings from users are modern pillars of collaborative filtering. Likert scale is a psychometric quantifier of ratings popular among the electronic commerce sites. In this paper, we consider the tasks of collecting Likert scale ratings of items and of finding the n-k best-rated items, i.e., the n items that are most likely to be the top-k in a ranking constructed from these ratings. We devise an algorithm, Pundit, that computes the n-k best-rated items. Pundit uses the probability-generating function constructed from the Likert scale responses to avoid the combinatorial exploration of the possible outcomes and to compute the result efficiently. Selection of the best-rated items meets, in practice, the major obstacle of the scarcity of ratings. We propose an approach that learns from the available data how many ratings are enough to meet a prescribed error. We empirically validate with real datasets the effectiveness of our method to recommend the collection of additional ratings.

Today ad hoc networks (MANET) are a more and more adopted technology. This is mainly due to the continuing development of networks, the growing need for mobility, miniaturization of networking devices, universal access to information and its sharing. In order to transmit messages between two given nodes in networks in general, we have to determine the best route to take by using routers. In MANETs the other intermediate network nodes will be used as gateways or relays. As these nodes can be mobile, and as the network topology varies, the problem of routing, which is about finding an optimal multihop route, is the most difficult challenge to overcome in MANETs.Indeed, this routing is a problem of optimization under such constraints like topology changes, volatility of links, limited storage and processing capacity, low bandwidth, low power level in batteries, etc. These binding characteristics make MANETs very vulnerable to attacks comparing to wired networks or infrastructure-based wireless networks.In this thesis, our work focuses on three areas aimed at analyzing the different types of routing protocols in MANETs in order to identify their shortcomings that security attacks can exploit, developing analytical models to simulate these attacks and the mobility, and offering secure algorithms to enhance cooperation during the process of routing in MANETs.On the first line of research we have pointed out the vulnerabilities of the main standardized wireless technologies, the faults specific to MANETs, and the security problems of the various types of their routing protocols.The second line of research focuses on the analysis of specific routing protocols used in MANETs and their shortcomings. This work has helped identify several variants of attacks, that can affect the routing protocols, their mode of operation, and some mechanisms to counter them.Our third research is devoted to some proposed analytical methods to simulate these attacks, and node mobility. The model used to simulate the Selfish and Sleep Deprivation attacks is based on game theory, which is a tool for analyzing the behavior of nodes. The model used to simulate the Blackhole cooperative, Blackmail, Bandwidth Saturation and Overflow attacks is based on malicious nodes and the number of hops. We conducted a simulation of the attacks with a C implementation of the proposed mathematical models.Then we have proposed algorithms to counter these attacks and have implemented them in C. These programs helped to test the proposed algorithms, and study the equilibrium states to determine the stability of the network nodes. In that state of stability the nodes are no longer prone to leave the network, taking account of their cooperation. The establishment of this state of stability can counter attacks which are based respectively on reputation, energy consumption, bandwidth saturation and routing tables overflow.We have equipped the ns2 software, the most popular network simulator, with new features to measure the impact of the above-mentioned attacks, which are most frequently encountered in MANETs. This is because the ns2 software has limited functionalities to simulate attacks. It does not take into account the attacks that affect the routing protocols used in MANET. The features we have added help bridge this gap., Aujourd’hui les réseaux ad hoc sans fil (MANETs) sont une technologie de plus en plus adoptée. Ceci est dû principalement au développement continu des réseaux, aux besoins croissants de mobilité, à la miniaturisation des équipements réseaux, à l’accès universel à l’information et à son partage. Pour transmettre des messages entre deux nœuds donnés dans les réseaux en général, il faut déterminer la meilleure route à emprunter à l’aide de routeurs. Dans les MANETs ce sont les autres nœuds intermédiaires du réseau qui vont faire office de passerelles ou de relais. Comme ces nœuds peuvent être mobiles, et comme la topologie du réseau est variable le problème du routage, qui consiste à trouver une route optimale multi-sauts, est le défi le plus difficile à surmonter dans les MANETs.En effet, ce routage est un problème d'optimisation sous des contraintes telles que les changements de topologies, la volatilité des liens, la capacité limitée de stockage, de traitement et de bande passante, le niveau d'énergie dans les batteries, etc. Ces caractéristiques contraignantes font que les MANET sont très vulnérables aux attaques, comparés aux réseaux filaires ou aux réseaux sans fil basés sur une infrastructure.Dans cette thèse, nos travaux portent essentiellement sur trois axes visant, à analyser les différents types de protocoles de routage dans les MANETs afin de déceler leurs insuffisances que les attaques sur la sécurité peuvent exploiter, à élaborer des modèles analytiques pour simuler ces attaques et la mobilité, et à proposer des algorithmes sécurisés pour renforcer la coopération dans le routage des réseaux mobiles ad hoc. Concernant le premier axe de recherche nous avons a mis en évidence les vulnérabilités des principales technologies sans fil standardisées, les failles spécifiques aux MANETs, ainsi que les problèmes de sécurisation des différents types de protocoles de routage dans ces réseaux. Le deuxième axe de recherche porte sur une analyse des protocoles de routages spécifiques utilisés dans les MANETs et de leurs insuffisances. Ce travail a permis de faire ressortir plusieurs variantes d’attaques, dont ces protocoles de routage sont souvent victimes, leur mode de fonctionnement, ainsi que certains mécanismes utilisés pour les contrer. Notre troisième axe de recherche est consacré à une proposition de méthodes analytiques pour simuler ces attaques, ainsi que la mobilité des nœuds. Le modèle utilisé pour simuler les attaques Selfish et Sleep Deprivation se fonde sur la théorie des jeux, qui est un outil d’analyse de comportements des nœuds. Le modèle utilisé pour simuler les attaques Blackhole coopérative, Blackmail, Saturation de la bande passante et Overflow se base sur les nœuds malicieux et le nombre de sauts. Nous avons procédé à une simulation de ces attaques grâce à une implémentation en C des modèles mathématiques proposés.Ensuite nous avons proposé des algorithmes pour contrer ces attaques et les avons implémentés en C. Ces programmes ont permis de tester les algorithmes proposés, et d’étudier les états d’équilibre pour déterminer la stabilité des nœuds du réseau, c’est-à-dire l’état où les nœuds ne souhaitent plus quitter le réseau compte tenu de leur coopération. L’établissement de cet état de stabilité permet de contrer les attaques qui se basent respectivement sur la réputation, la consommation d’énergie, la saturation de la bande passante et le débordement des tables de routage.Nous avons doté le logiciel ns2, le simulateur réseau le plus populaire, de nouvelles fonctionnalités afin de mesurer l’impact des attaques précitées, qui sont les plus fréquemment rencontrées dans les MANETs, car le logiciel ns2 présente des fonctionnalités limitées pour simuler les attaques. Il ne prend donc pas en compte les attaques rencontrées au niveau des protocoles de routage des MANETs. Les fonctionnalités que nous avons ajoutées permettent de combler cette lacune.

International audience; Ce travail exploratoire décrit et permet de comprendre les perceptions et pratiques RSO de 29 dirigeants de TPMEs au Sénégal. Il apporte un premier éclairage indispensable à la question suivante : comment adapter la définition de la RSO à la réalité des TPMEs Africaines? L'apport essentiel de ce travail est de révéler que dans les faits, les TPMEs sénégalaises pratiquent la RSO : une RSO ad hoc, localisée ou de proximité qui donne la priorité aux parties prenantes les plus proches ; centrée sur le philanthropique et le social ; dont les fondements sont éthiques et moraux et épousent la logique des valeurs, moeurs, façons de faire et de penser, présents au Sénégal.

Session 1 : Construction, peuplement et exploitation d'ontologies; National audience; Cet article décrit la construction de l'ontologie de la schistosomiase (IDOSCHISTO). Elle est conçue comme une extension de l'ontologie noyau des maladies infectieuses (IDO) afin d'assurer son interopérabilité avec les ontologies de domaine des maladies infectieuses existantes. IDOSCHISTO importe intégralement ou partiellement des ontologies du domaine médical conçues pour des besoins spécifiques propres aux maladies infectieuses. Il s'agit par exemple des ontologies concernant la transmission des agents pathogènes, le diagnostic, les études cliniques et biologiques, etc. IDOSCHISTO est une ontologie modulaire de la schistosomiase intégrant les points de vue épidémiologique, clinique et biologique de la maladie. Elle a pour finalité de devenir une référence dans le domaine des maladies infectieuses en facilitant la communication et l'interopérabilité entre les différents acteurs impliqués et en supportant le raisonnement dans des contextes d'usage variés tels que la veille sanitaire, l'aide au diagnostic et à la prescription médicamenteuse, la gestion du dossier patient, les annotations biologiques, etc.

It has been shown that living in risky environments, as well as having a risky occupation, can moderate risk-tolerance. Despite the involvement of dopamine in the expectation of reward described by neurobiologists, a GWAS study was not able to demonstrate a genetic contribution of genes involved in the dopaminergic pathway in risk attitudes and gene candidate studies gave contrasting results. We test the possibility that a genetic effect of the DRD4-7R allele in risk-taking behavior could be modulated by environmental factors. We show that the increase in risk-tolerance due to the 7R allele is independent of the environmental risk in two populations in Northern Senegal, one of which is exposed to a very high risk due to dangerous fishing.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIRE; International audience; In this paper we propose a mathematical model of the Typha growth and analyse its stability. The model that we plan to study describes the dynamics of the plant population. The theoretical study of this model determines the key factors of the Typha proliferation. We present the analysis of equilibrium solutions and lead a study of their local stability.This constitutes a first step towards a more detailed study of the nonlinear dynamics of this model.

International audience; In tetrahydrofuran, the electrochemical reduction of Cp2TiIVCl2 (2 mM) generated three titanium(III) complexes which were in equilibrium: [Cp2TiCl2]•−, [Cp2TiCl]• and (Cp2TiCl)2. Although the anion radical [Cp2TiCl2]•− was the main species produced under these conditions, cyclic voltammetry investigations clearly showed that the proportion of the three electrogenerated TiIII complexes can be modified as a function of the amounts of chloride ion present in the solution. Accordingly, the presence of Mg2+ ions, which led to the consumption of chloride ions through the formation of MgCl2, favoured the formation of [Cp2TiCl]• and, consequently, of the corresponding dimer (Cp2TiCl)2. The electrochemical behaviours of Cp2TiIVCl2 and of the electrogenerated low-valent Ti complexes were also investigated in the presence of amide and alkyne derivatives. Under these conditions, titanium complexes could not only interact with the amide carbonyl group, but also with the alkyne triple bond, provided the latter was not sterically hindered. Interestingly, the carbonyl group and the triple bond had antagonist effects on redox properties of titanium(III) complexes.

International audience; This paper describes two prototypes of an on-site Early Warning Water Quality Monitoring System (EWWQMS) for pesticide quantification in natural waters. As many pesticides are non-fluorescent, the EWWQMS setup uses UV photoconversion to form highly fluorescent photoproducts. To enhance sensitivity, the two prototypes use micellar-enhanced fluorescence with surfactant (cetyl trimethyl ammonium chloride) in aqueous solution. To improve specificity, four UV LEDs at different wavelengths then excite the fluorescent photoproducts. The EWWQMS prototypes also employ UV absorption for quantification of non-photosensitive pesticides. The first prototype detects the pesticides via a diode array spectrometer. The second system is developed with higher resolution spectrometer and an intensified CCD camera detection to improve the sensitivity of the method. These experimental set-ups are described, explained and tested. Analytical applications were carried out online in CTAC aqueous solution, for the determination of isoproturon, flufenoxuron and profenofos. The calibration curves obtained are linear over one order of magnitude, and the detection limits are in the ng mL−1 range. The analytical performances of these new methods are good compared with other published classical micellar enhanced photo-induced fluorescence methods for the determination of pesticides in aqueous solutions. Our results show that these EWWQMS prototypes can be used as a warning system to protect against pesticide contamination exceeding the threshold of treatment capabilities at industrial facilities using natural waters.

International audience; A simple and sensitive thermochemically induced fluorescence (TIF) method was developed to determine deltamethrin, an insecticide which has toxic effects on human beings and animals. After optimisation at different pH, temperature was increased from 25 to 50°C. TIF method is based on the thermolysis transformation of naturally non-fluorescent pesticides into a fluorescent thermoproduct. The thermolysis kinetics reaction investigated in water at optimal pH 12 and after 4 minutes heating at 40°C made it possible to obtain a low mean half-life time (t1/2 = 1.41 ± 0.06 min), which shows that deltamethrin degrades very rapidly due to heat. The obtained calibration curve gave correlation coefficients close to unity. The limit of detection (LOD = 4.4 ng mL−1) and quantification (LOQ = 15 ng mL−1) values were very low, showing the high sensitivity of the TIF method. TIF method was applied to determination of deltamethrin residues in tap and well waters by standard addition procedure, with satisfactory recovery values between 107.6 and 111.4%. The relative standard deviation (RSD) value of the measured concentrations in spiked water samples was less than 6%, which demonstrated good reproducibility of the TIF method.

Free full-text view-only: https://rdcu.be/b6dw3; International audience; This paper describes prototypes of an on-site early warning water quality monitoring system (EWWQMS) for pesticide quantification in natural waters by fluorescence and absorbance. As many pesticides are not naturally fluorescent, this EWWQMS uses UV irradiation to transform these compounds into highly fluorescent photoproducts and obtain sufficient sensitivity. To obtain a better specificity, the system uses four UV LEDs at different wavelengths to excite the fluorescent photoproducts. For pesticides that are not sensitive to photoconversion, the EWWQMS prototypes also use UV absorption for their quantification, thus offering a wider application range. A first system uses a diode array spectrometer for detection. A second system uses a higher resolution spectrometer and an intensified CCD camera detection to increase sensitivity. Analytical applications were conducted for the determination of fipronil, acetamipride, cyprodinil, trifluraline and pendimethaline in water using both the EWWQMS prototypes. The analytical performances of these new systems are good compared with other photo-induced fluorescence methods already published. Limits of detection without pre-concentration are in the range of 0.2 to 3 ng mL−1 and the recovery values range from 95 to 108%. These results show that the EWWQMS prototypes can be used as an alert system to protect industrial plants from pesticide contaminations that exceed the capabilities of their cleaning processes.

International audience; We propose an Aitken estimator for Gini regression. The suggested A-Gini estimator is proven to be a U-statistics. Monte Carlo simulations are provided to deal with heteroskedasticity and to make some comparisons between the generalized least squares and the Gini regression. A Gini-White test is proposed and shows that a better power is obtained compared with the usual White test when outlying observations contaminate the data.

International audience; The ligand N'-(2-hydroxy-3-methoxybenzylidene)nicotinohydrazide (H2L) was prepared by reaction of nicotinohydrazide with 2-hydroxy-3-methoxybenzaldehyde in a reflux ethanol solution. The lanthanides complexes were prepared by reaction of the ligand with the lanthanide nitrate. These complexes are well characterized by elemental analysis, IR, UV spectroscopies, conductance and room temperature magnetic moment measurement.The structure of the complexes was determined by single X-ray diffraction technic. Thecomplexes of Gd and Tb are isostructural and are formulated as {[Ln (HL)(H2O)2(NO3)]2.(NO3)2.(H2O)2}. Inthese structures, each Ln atom is nine coordinated. In the crystal of the dinuclear complex {[Eu2(HL)2(H2O)2(NO3)3].(NO3).(H2O)2} one Eu(III) center is nine-coordinated and the other one is tencoordinated. One nitrate anion acts in 2-coordination mode and as 2-mode Bridge between the two Eu (III) centers. In all the complexes, the ligand acts as bridge in tetradentate fashion. The nitrogen and the oxygen atoms of the hydrazino moietyare coordinated to one Ln (III) center and the oxygen atom of the methoxy group is coordinated the otherLn (III) center. The phenolate oxygen atom bridges the two Ln (III) centers. One nitrate group acts in bidentate manner to each Ln (III). Two nitrate groups remain uncoordinated. In both Gd and Tb dinuclear complexes the coordination polyhedral are best described as a tricapped trigonal prismfor each of the two centers.In the dinuclear complex of Eu, the polyhedron of the ten-coordinated Eu can be regarded as a 1333stacking patternwhile the polyhedron of the nine-coordinated Eu is best described as a monocapped square antiprism. The molecules are linked together in each case by multiple hydrogen bond interaction resulting in a three-dimensional network.

International audience; The objective of this article is, on the one hand, to apprehend the risky management situations in the context of the project and on the other hand to analyse them according to the trajectory of the project and the nature of the project in question. By conducting a questionnaire survey, with a sample of 187 persons working in project context and having met 3170 managerial situations, was carried out in the Moroccan context. After discussing the relevance of constructing the variable "degree of risk" with the two variables "uncertainty" and "chrono-adaptation", the chi-square independence tests carried out with the X-SAT solution highlighted the management situations that carry more risk in the context studied. By conducting correspondence analyses with SPSS, our work argues that these situations appear more at the beginning of the project and are predominant in projects of the "infrastructure" or "communication" type.; L’objectif de cet article est d’une part, d’appréhender les situations de management risquées en contexte de projet et d’autre part, de les analyser en fonction de la trajectoire du projet et de la nature du projet en question. Pour ce faire une enquête par questionnaire, auprès d’un échantillon de 187 personnes travaillant en contexte de projet et ayant rencontré 3170 situations managériales, a été effectuée dans le contexte marocain. Après avoir discuté de la pertinence de construire la variable « degré de risque » avec les deux variables « incertitude » et « chrono-adaptation », les tests d’indépendance du khi-deux effectués avec la solution X-SAT ont mis en évidence les situations de management porteuses de plus de risque dans le contexte étudié. En procédant à des analyses de correspondance avec SPSS, nos travaux soutiennent que ces situations en question apparaissent plus en début de projet et sont prépondérants dans des projets de type « infrastructure » ou « communication ».

International audience

International audience

International audience; In this paper, we focus on numerical aspects of structural optimization. We combine shape and topological optimization of structure with a fictitious domain approach. After recalling some standard results of shape and topological optimization, we build an algorithm inspired from the extended finite elements method (Xfem) principles and give some numerical results. Numerical results confirm that the method is efficient and gives better result compared with the classical shape optimization techniques.