Les demandes sociales de restauration des rivières et leurs traductions scientifiques et politiques

La restauration des rivières n'est pas qu'une préoccupation des experts et des écologistes. Une rétrospective des demandes sociales en faveur d'une préservation et d'une réhabilitation des cours d'eau montre que celles-ci ont été portées par des intérêts multiples et parfois contradictoires. La fin du 19ème siècle et début du 20ème est marquée par des préoccupations de dépeuplement des cours d'eau, la période de reconstruction d'après guerre met l'accent sur la qualité de l'eau brute à des fins d'adduction et de distribution d'eau, depuis les années 70 le courant écologiste trouve de nombreux relais dans la population à travers les activités de nature revendiquée par les classes moyennes comme partie intégrante de leur qualité de vie. Ces trois exemples montrent en outre que les préoccupations sociales sont diversement interprétées par les scientifiques et les politiques qui contribuent à modifier leur expression en agissant sur les connaissances et les moyens d'action ou la réglementation. A travers ces quelques exemples nous montrons que les questions de mise en oeuvre de la directive cadre s'appréhendent mieux en tenant compte des aspirations sociales qui ont conduit à l'adoption de cette directive / River restoration does not only concern experts and ecologists. Social demands in favour of river protection and enhancement have been historically diverse and contradictory. Three examples are analysed to support this point. Implementing the new framework directive requires to take into account which social expectations were at stake while the directive was adopte

Damage by insects pests to the Djingarey Ber Mosque in Timbuktu: detection and control

The Djingarey Ber Mosque in Timbuktu (Mali) is one of the most significant earthen construction in West Africa. Originally constructed in 1327, it was included in 1988 on the World Heritage UNESCO List for its unique architecture and historical importance. During its restoration, recently undertaken by the Aga Khan Trust for Culture, the wooden parts of the roof and architraves showed clear signs of threatening insect presence. In order to identify the pests responsible of the damage, evaluate its extent and suggest a proper control strategy, a detailed survey was performed inside the Mosque complex and in its immediate surroundings. The entomological inspection, performed in the dry-cold season, allowed to detect signs of insect damage in most of the wooden elements, even in the recently replaced beams, but also in walls, pillars and the precious decorated panels. Damages in the wood elements could be attributed to Amitermes evuncifer Silvestri (Termitidae), Bostrychoplites zycheli Marseuli (Bostrichidae) and Lyctus africanus Lesne (Lyctidae), which were collected alive on site. Injures in the walls and decorated panels appeared to be performed by hymenopterans such as \u201cplasterer bees\u201d (Colletidae) and Sphecidae. From the evaluation of the type and extent of damage in relation to the architecture and materials used in its construction and decoration, the most serious pest and the worse threat for the mosque is represented by termites. Control and preventive measures, in the view of a sustainable, long-lasting integrated management are suggested

Comment l'approche écosystémique reconfigure l'interface science/politique dans la planification stratégique de l'eau sur l'estuaire de la Gironde

14ème congrès AFSP. Section thématique 16 : Savoirs et pouvoirs bureaucratiques dans le gouvernement de la nature, Montpellier, FRA, 10-/07/2017 - 12/07/2017National audienceThe Dublin conference on integrated water resource management and the French water law of 1992 promoted the ecosystem approach (EA) in water policies. The European water framework directive further reinforced it. EA differs from a utilitarian conception of water and conceptualizes water as a shared living system, which management objectives must be publicly defined, while preserving all ecological habitats, notably wetlands. We look at wetland boundary setting as both a political and scientific stake to assess whether EA induces changes in the government of nature. We focus our attention on four processes (4As) at the interface of science and policy: knowledge Acquisition, knowledge Aggregation in policy tools, knowledge Articulation in public decision and knowledge Accumulation. The case study of the Gironde estuary planning shows that new knowledge on soils were acquired and then politicized and discarded from the decision process. However this knowledge accumulated in bureaucracies and is recycled in risk policies.La préservation des écosystèmes a été mise à l'agenda des politiques de l'eau en 1992, avec la conférence internationale de Dublin sur la gestion intégrée des ressources en eau et l'adoption en France d'une nouvelle loi sur l'eau. Elle a été réaffirmée avec la directive cadre européenne (DCE) de 2000. L'approche écosystémique rompt avec une conception de l'eau qui ne serait qu'une ressource pour des usages socio-économiques. Elle aborde l'eau comme un milieu naturel et partagé, dont les objectifs de gestion doivent être définis de manière concertée tout en préservant les habitats écologiques, notamment les zones humides. La délimitation de ces zones est un enjeu à l'interface entre la science et la politique. Pour étudier les éventuels changements introduits par l'approche écosystémique dans la planification de la gestion de l'eau, nous étudions cette interface science/politique à travers quatre processus (4A) : l'Acquisition de connaissances, leur Agrégation dans des instruments d'action publique, leur mobilisation dans l'Argumentation et les processus d'Accumulation de ces connaissances. A travers l'exemple du SAGE de l'estuaire de la Gironde, nous montrons l'incorporation de savoirs pédologiques puis leur progressive exclusion sous l'effet de la politisation. Mais ces connaissances s'accumulent néanmoins et sont recyclées dans la politique de prévention des risques

Optimizing drip irrigation for eggplant crops in semi-arid zones using evolving thresholds

AbstractField experiments were combined with a numerical model to optimize drip irrigation management based on soil matric potential (SMP) measurements. An experimental crop of eggplant was grown in Burkina Faso from December 2014 to March 2015 and plant response to water stress was investigated by applying four different irrigation treatments. Treatments consisted in using two different irrigation depths (low or high), combined with a water provision of 150%, 100% or 66% (150/100/66) of the maximum crop evapotranspiration (T150low, T66low, T100high, T66high). Soil matric potential measurements at 5, 10 and 15cm depth were taken using a wireless sensor network and were compared with measurements of plant and root biomass and crop yields. Field data were used to calibrate a numerical model to simulate triggered drip irrigation. Different simulations were built using the software HYDRUS 2D/3D to analyze the impact of the irrigation depth and frequency, the irrigation threshold and the soil texture on plant transpiration and water losses. Numerical results highlighted the great impact of the root distribution on the soil water dynamics and the importance of the sensor location to define thresholds. A fixed optimal sensor depth of 10 cm was found to manage irrigation from the vegetative state to the end of fruit development. Thresholds were defined to minimize water losses while allowing a sufficient soil water availability for optimal crop production. A threshold at 10cm depth of −15kPa is recommended for the early growth stage and −40kPa during the fruit formation and maturation phase. Simulations showed that those thresholds resulted in optimal transpiration regardless of the soil texture so that this management system can constitute the basis of an irrigation schedule for eggplant crops and possibly other vegetable crops in semi-arid regions

Quadratic optimal functional quantization of stochastic processes and numerical applications

In this paper, we present an overview of the recent developments of functional quantization of stochastic processes, with an emphasis on the quadratic case. Functional quantization is a way to approximate a process, viewed as a Hilbert-valued random variable, using a nearest neighbour projection on a finite codebook. A special emphasis is made on the computational aspects and the numerical applications, in particular the pricing of some path-dependent European options.Comment: 41 page

Developmental Acquisition of a Rapid Calcium-Regulated Vesicle Supply Allows Sustained High Rates of Exocytosis in Auditory Hair Cells

Auditory hair cells (HCs) have the remarkable property to indefinitely sustain high rates of synaptic vesicle release during ongoing sound stimulation. The mechanisms of vesicle supply that allow such indefatigable exocytosis at the ribbon active zone remain largely unknown. To address this issue, we characterized the kinetics of vesicle recruitment and release in developing chick auditory HCs. Experiments were done using the intact chick basilar papilla from E10 (embryonic day 10) to P2 (two days post-hatch) by monitoring changes in membrane capacitance and Ca2+ currents during various voltage stimulations. Compared to immature pre-hearing HCs (E10-E12), mature post-hearing HCs (E18-P2) can steadily mobilize a larger readily releasable pool (RRP) of vesicles with faster kinetics and higher Ca2+ efficiency. As assessed by varying the inter-pulse interval of a 100 ms paired-pulse depolarization protocol, the kinetics of RRP replenishment were found much faster in mature HCs. Unlike mature HCs, exocytosis in immature HCs showed large depression during repetitive stimulations. Remarkably, when the intracellular concentration of EGTA was raised from 0.5 to 2 mM, the paired-pulse depression level remained unchanged in immature HCs but was drastically increased in mature HCs, indicating that the Ca2+ sensitivity of the vesicle replenishment process increases during maturation. Concomitantly, the immunoreactivity of the calcium sensor otoferlin and the number of ribbons at the HC plasma membrane largely increased, reaching a maximum level at E18-P2. Our results suggest that the efficient Ca2+-dependent vesicle release and supply in mature HCs essentially rely on the concomitant engagement of synaptic ribbons and otoferlin at the plasma membrane

Comment l'approche écosystémique reconfigure l'interface science/politique dans la planification stratégique de l'eau sur l'estuaire de la Gironde

14ème congrès AFSP. Section thématique 16 : Savoirs et pouvoirs bureaucratiques dans le gouvernement de la nature, Montpellier, FRA, 10-/07/2017 - 12/07/2017National audienceThe Dublin conference on integrated water resource management and the French water law of 1992 promoted the ecosystem approach (EA) in water policies. The European water framework directive further reinforced it. EA differs from a utilitarian conception of water and conceptualizes water as a shared living system, which management objectives must be publicly defined, while preserving all ecological habitats, notably wetlands. We look at wetland boundary setting as both a political and scientific stake to assess whether EA induces changes in the government of nature. We focus our attention on four processes (4As) at the interface of science and policy: knowledge Acquisition, knowledge Aggregation in policy tools, knowledge Articulation in public decision and knowledge Accumulation. The case study of the Gironde estuary planning shows that new knowledge on soils were acquired and then politicized and discarded from the decision process. However this knowledge accumulated in bureaucracies and is recycled in risk policies.La préservation des écosystèmes a été mise à l'agenda des politiques de l'eau en 1992, avec la conférence internationale de Dublin sur la gestion intégrée des ressources en eau et l'adoption en France d'une nouvelle loi sur l'eau. Elle a été réaffirmée avec la directive cadre européenne (DCE) de 2000. L'approche écosystémique rompt avec une conception de l'eau qui ne serait qu'une ressource pour des usages socio-économiques. Elle aborde l'eau comme un milieu naturel et partagé, dont les objectifs de gestion doivent être définis de manière concertée tout en préservant les habitats écologiques, notamment les zones humides. La délimitation de ces zones est un enjeu à l'interface entre la science et la politique. Pour étudier les éventuels changements introduits par l'approche écosystémique dans la planification de la gestion de l'eau, nous étudions cette interface science/politique à travers quatre processus (4A) : l'Acquisition de connaissances, leur Agrégation dans des instruments d'action publique, leur mobilisation dans l'Argumentation et les processus d'Accumulation de ces connaissances. A travers l'exemple du SAGE de l'estuaire de la Gironde, nous montrons l'incorporation de savoirs pédologiques puis leur progressive exclusion sous l'effet de la politisation. Mais ces connaissances s'accumulent néanmoins et sont recyclées dans la politique de prévention des risques