Evaluation de la contamination métallique des moules Mytilus gallo provincialis et des sédiments marins au niveau des côtes de la région de Dakar (Sénégal)

Les rejets industriels et domestiques au Sénégal sont versés directement dans le milieu aquatique sans aucun traitement préalable. Dans le présent travail, nous avons étudié le degré de contamination du littoral dakarois par un suivi spatio-temporel des teneurs de certains éléments métalliques (cadmium, chrome et plomb) au niveau des moules et des sédiments. Pour cela, six stations de prélèvement ont été choisis en fonction des activités qui s’y déroulent: la zone de Mbao, les plages de débarquement des produits halieutiques de Hann et Soumbédioune, les alentours du port de Dakar, Cap Manuel et l’île de Sarpent. En plus, cette étude vise à évaluer la variation intersaison de cette contamination. Les métaux lourds étudiés dans ce travail sont dosés par un spectromètre d’émission atomique à arc électrique. Les résultats obtenus montrent une contamination importante dans tout l’étendu du littoral, surtout pendant la saison des pluies (Août) dans les moules et en saison sèche (Mai) au niveau des sédiments. Les teneurs en plomb, chrome et cadmium les plus élevées, accumulées par les moules ont été détectées au port avec des valeurs respectives de 380, 298 et 18,5 μg/g de poids sec et à Hann avec respectivement 307, 268 et 3 μg/g de poids sec. Les résultats de mesure ont montré également, dans les deux sites, des teneurs en plomb, chrome, et cadmium très élevées au niveau des sédiments avec des valeurs respectives de 707, 1150 et 24 μg/g de poids sec au port. Pour Hann, les concentrations mesurées sont respectivement de 654, 752 et 5 μg/g de poids sec. Les limites de détection des électrolytes varient entre 0,01 et 0,1 mg/L. Les valeurs trouvées sont largement supérieures à la norme établie par la Communauté Economique Européenne (CEE). En effet, la norme autorisée pour le plomb, le cadmium et le chrome au niveau des moules est de 1,5 μg/g du poids sec.Mots clés: Métaux lourds, moule, sédiment, toxicité, émission atomique

Repackaging agricultural research for greater impact on agricultural growth in Africa

Despite the enormous research activities embarked upon by the various research entities in Africa over time, the expected research impacts remain obscure. This paper is a compilation of facts and figures from published peer reviewed articles, agricultural research and development reports from national and international institutions, and base-line data from the Africa Rice Centre aimed at elucidating the performance of agricultural research in Africa between 1960 and 2010. It discusses the constraints to the visible impact of agricultural research on the growth of Africa’s economy, and suggests how to repackage agricultural research for more visible impact on Africa’s economic growth. Results show that agricultural research has been beneficial for African agriculture widely and is believed to be the backbone of the economic growth of the continent. Agricultural research has also served as the bedrock of agricultural technological transformation to enhance agricultural growth. Research has helped to increase agricultural production and productivity and food security in several countries. Also, investment in agricultural research has yielded positive impact on poverty reduction and food security. However, food security and poverty are still visibly mining the African population. The major constraints in the utilization of agricultural research results are the lack of adequate public investment in agriculture, lack of well-trained researchers, inadequate research infrastructures and poor management of the agricultural research and development system. Findings show that in order to package agricultural research for visible impact on the economy, agricultural research systems would need to be adequately funded and handled by skilled human resources under good governance. An effective innovative agricultural policy would demand the initial acknowledgment that a break from the past is necessary to ‘produce more and better’ in Africa and that successful agricultural research systems should be designed in a framework of co-construction, co-execution and co-evaluation

A Study of Machine Learning Techniques for Daily Solar Energy Forecasting using Numerical Weather Models

Proceedings of: 8th International Symposium on Intelligent Distributed Computing (IDC'2014). Madrid, September 3-5, 2014Forecasting solar energy is becoming an important issue in the context of renewable energy sources and Machine Learning Algorithms play an important rule in this field. The prediction of solar energy can be addressed as a time series prediction problem using historical data. Also, solar energy forecasting can be derived from numerical weather prediction models (NWP). Our interest is focused on the latter approach.We focus on the problem of predicting solar energy from NWP computed from GEFS, the Global Ensemble Forecast System, which predicts meteorological variables for points in a grid. In this context, it can be useful to know how prediction accuracy improves depending on the number of grid nodes used as input for the machine learning techniques. However, using the variables from a large number of grid nodes can result in many attributes which might degrade the generalization performance of the learning algorithms. In this paper both issues are studied using data supplied by Kaggle for the State of Oklahoma comparing Support Vector Machines and Gradient Boosted Regression. Also, three different feature selection methods have been tested: Linear Correlation, the ReliefF algorithm and, a new method based on local information analysis.Publicad

PIP5KIβ Selectively Modulates Apical Endocytosis in Polarized Renal Epithelial Cells

Localized synthesis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at clathrin coated pits (CCPs) is crucial for the recruitment of adaptors and other components of the internalization machinery, as well as for regulating actin dynamics during endocytosis. PtdIns(4,5)P2 is synthesized from phosphatidylinositol 4-phosphate by any of three phosphatidylinositol 5-kinase type I (PIP5KI) isoforms (α, β or γ). PIP5KIβ localizes almost exclusively to the apical surface in polarized mouse cortical collecting duct cells, whereas the other isoforms have a less polarized membrane distribution. We therefore investigated the role of PIP5KI isoforms in endocytosis at the apical and basolateral domains. Endocytosis at the apical surface is known to occur more slowly than at the basolateral surface. Apical endocytosis was selectively stimulated by overexpression of PIP5KIβ whereas the other isoforms had no effect on either apical or basolateral internalization. We found no difference in the affinity for PtdIns(4,5)P2-containing liposomes of the PtdIns(4,5)P2 binding domains of epsin and Dab2, consistent with a generic effect of elevated PtdIns(4,5)P2 on apical endocytosis. Additionally, using apical total internal reflection fluorescence imaging and electron microscopy we found that cells overexpressing PIP5KIβ have fewer apical CCPs but more internalized coated structures than control cells, consistent with enhanced maturation of apical CCPs. Together, our results suggest that synthesis of PtdIns(4,5)P2 mediated by PIP5KIβ is rate limiting for apical but not basolateral endocytosis in polarized kidney cells. PtdIns(4,5)P2 may be required to overcome specific structural constraints that limit the efficiency of apical endocytosis. © 2013 Szalinski et al

Teacher training in the field of health promotion: a proposal for International collaboration and preparation of a symposium for the 20th IUHPE World Conference

Schools are considered to be settings for both health education and health promotion. But the core business of schools is actually focussed on educational outcomes, not reducing health problems. In most countries, schools give low priority to health promotion and school staffs, mainly teachers, are not aware of their role in health promotion. Studies show that teachers who have received health promotion training tend to be involved more frequently in health promotion projects and have a more comprehensive approach to health education. Pre-service and In-service staff training is then a main challenge. That’s the reason why we have launched an initiative to join international forces to strengthen and advocate for teacher training in health promotion. The main goals are: develop research, affirm and reinforce the work done in teacher training in health promotion, support the institutes/colleges/universities in the provision of initial and in-service teacher training and stimulate international partnership work.LIBEC/CIFPEC - unidade de investigação 16/644 da FCT

Landscape Ecology of Sylvatic Chikungunya Virus and Mosquito Vectors in Southeastern Senegal

The risk of human infection with sylvatic chikungunya (CHIKV) virus was assessed in a focus of sylvatic arbovirus circulation in Senegal by investigating distribution and abundance of anthropophilic Aedes mosquitoes, as well as the abundance and distribution of CHIKV in these mosquitoes. A 1650 km2 area was classified into five land cover classes: forest, barren, savanna, agriculture and village. A total of 39,799 mosquitoes was sampled from all classes using human landing collections between June 2009 and January 2010. Mosquito diversity was extremely high, and overall vector abundance peaked at the start of the rainy season. CHIKV was detected in 42 mosquito pools. Our data suggest that Aedes furcifer, which occurred abundantly in all land cover classes and landed frequently on humans in villages outside of houses, is probably the major bridge vector responsible for the spillover of sylvatic CHIKV to humans

Poverty and Wellbeing Impacts of Microfinance : What Do We Know?

Over the last 35 years, microfinance has been generally regarded as an effective policy tool in the fight against poverty. Yet, the question of whether access to credit leads to poverty reduction and improved wellbeing remains open. To address this question, we conduct a systematic review of the quantitative literature of microfinance’s impacts in the developing world, and develop a theory of change that links inputs to impacts on several welfare outcomes. Overall, we find that the limited comparability of outcomes and the heterogeneity of microfinance-lending technologies, together with a considerable variation in socio-economic conditions and contexts in which impact studies have been conducted, render the interpretation and generalization of findings intricate. Our results indicate that, at best, microfinance induces short-term dynamism in the financial life of the poor; however, we do not find compelling evidence that this dynamism leads to increases in income, consumption, human capital and assets, and, ultimately, a reduction in poverty

Dynamic modeling of the reactive twin-screw co-rotating extrusion process: experimental validation by using inlet glass fibers injection response and application to polymers degassing

International audienceIn this paper is described an original dynamic model of a reactive co-rotating twinscrew extrusion (TSE) process operated by the Rhodia company for the Nylon-66 degassing finishing step. In order to validate the model, dynamic experiments have been performed on a small-scale pilot plant. These experiments consist in a temporary injection of glass fibers at the inlet of the extruder after it has reached a given operating point. The outlet glass fibers mass fraction time variation is then measured. This experiment does not lead to the RTD measurement. As a matter of fact, due to the high quantity of glass fibers that is introduced, the behavior of the flow through the extruder is perturbed so that the glass fibers cannot be considered as an inert tracer. The dynamic model that we have published elsewhere (Choulak et al., Ind. Eng. Chem. Res., 2004, 43(23), 7373-7382) is adapted to take into account this nonlinear behavior of the extruder with respect to the glass fibers injection and is favorably compared to experimental results. The description of the degassing operation is also included in the model. The model allows simulations of the complete dynamic behavior of the process. When the steady state is reached, the good position of the degassing vent with respect to the partially and fully filled zones positions can also be checked, thus illustrating the way the model can be used for design purposes

TRAF4 is a novel phosphoinositide-binding protein modulating tight junctions and favoring cell migration

Tumor necrosis factor (TNF) receptor-associated factor 4 (TRAF4) is frequently overexpressed in carcinomas, suggesting a specific role in cancer. Although TRAF4 protein is predominantly found at tight junctions (TJs) in normal mammary epithelial cells (MECs), it accumulates in the cytoplasm of malignant MECs. How TRAF4 is recruited and functions at TJs is unclear. Here we show that TRAF4 possesses a novel phosphoinositide (PIP)-binding domain crucial for its recruitment to TJs. Of interest, this property is shared by the other members of the TRAF protein family. Indeed, the TRAF domain of all TRAF proteins (TRAF1 to TRAF6) is a bona fide PIP-binding domain. Molecular and structural analyses revealed that the TRAF domain of TRAF4 exists as a trimer that binds up to three lipids using basic residues exposed at its surface. Cellular studies indicated that TRAF4 acts as a negative regulator of TJ and increases cell migration. These functions are dependent from its ability to interact with PIPs. Our results suggest that TRAF4 overexpression might contribute to breast cancer progression by destabilizing TJs and favoring cell migration