Influence of water on the circulation of the West Nile Virus in horses in Southern France

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Diet of Reed Warblers Acrocephalus scirpaceus at two stopover sites in Morocco during autumn migration

Diet of the Reed Warbler (Acrocephalus scirpaceus) was estimated by means of forced regurgitations of captured individuals during autumn migration at Kerbacha and Sidi Bou Ghaba, two wetland sites located respectively on the Mediterranean and Atlantic coasts in Morocco. Overall, 88 emetic samples were collected and 17 prey taxa were identified from 789 food items with a predominance of wasps (Hymenoptera) and beetles (Coleoptera) at Kerbacha, and ants including alate forms (Hymenoptera) at Sidi Bou Ghaba. Prey diversity and taxonomic distribution differed significantly between the two sites. Birds at Sidi Bou Ghaba had a lower food intake but fed on larger and less mobile prey than at Kerbacha where most diet samples comprised a large number of small flying prey. These between-site differences are assumed to reflect local food availability and may partly explain the different migratory strategies observed. The short stay and high fattening rate of Reed Warblers at Kerbacha can be associated with the high food intake of a few, abundant prey. The longer stopover duration and lower fattening rate at Sidi Bou Ghaba can be associated with higher diet diversity and lower feeding rate suggesting that prey abundance is globally low except for ephemeral patchily distributed food source such as swarms of flying ants, which are extensively exploited by Reed Warblers whenever availableLe régime alimentaire de la Rousserolle effarvatte (Acrocephalus scirpaceus) pendant la migration automnale (septembre-octobre 2000) a été étudié par analyse de régurgitats dans deux zones humides marocaines, Kerbacha en région Méditerranéenne et Sidi Bou Ghaba en région Atlantique. Dix-sept catégories de proies ont été identifiées dans 88 régurgitats totalisant 789 items, avec une prédominance de guêpes (Hyménoptères) et de coléoptères à Kerbacha, et de fourmis (ailées et non ailées) et coléoptères à Sidi Bou Ghaba. La distribution taxinomique des proies et leur diversité diffèrent significativement entre les deux sites. Les oiseaux consomment un plus petit nombre de proies de plus grande taille et de plus faible mobilité à Sidi Bou Ghaba, comparativement à Kerbacha où un grand nombre de petites proies volantes caractérisent la majorité des régurgitats. Ces différences sont vraisemblablement dues à des variations dans la disponibilité locale des proies qui peuvent expliquer en partie les stratégies migratoires différentes utilisées aux deux sites. Ainsi, le court séjour et le taux d'engraissement élevé à Kerbacha peuvent être associés à un taux d'alimentation supérieur grâce à l'abondance de quelques taxons fortement consommés. A Sidi Bou Ghaba, où la durée de stationnement est plus longue et le taux d'engraissement moindre, les rousserolles ont un régime alimentaire plus diversifié et un taux d'alimentation faible suggérant que les proies sont généralement peu abondantes à l'exception des fourmis volantes, une ressource alimentaire ponctuellement surabondante mais peu prévisible dont les rousserolles font bon usage

The neuropeptide 26RFa in the human gut and pancreas: potential involvement in glucose homeostasis

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Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions

International audienceAgricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter “crop heterogeneity”) can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production

Commande de machine asynchrone sans capteur de vitesse : Application à la traction ferroviaire

The problem of speed sensorless control of induction machine is a well-studied problem in the field of automatic control and electrical engineering. This work addresses the problem of the feasibility of induction machine control over the whole speed range and for any type of induction machine, aiming at being used in a railway application. An intensive study of observability has defined a continuous quantitative measurement of the speed observability, named observability index. An observer was developped to confirme the correspondence between low-observability index areas and poor observation quality. The observability index defined in this thesis is thus a way to predict the observation performance of systems. The main originality of the work presented in this thesis is the use of this observability index in the induction machine speed sensorless drive. By taking advantage of the degree of freedom given by the variation of the flux amplitude, we propose to guarantee the observability index value above a given threshold while respecting the other constraints of the control. The speed observation becomes precise over the entire speed range, and a long time operation is possible on any point, without interfering with torque regulation. Experiments on real-time simulator confirm these results, including when slipping and sliding occurs. The electrical parameter observation is also studied to ensure the accuracy of speed observation. For this, the sensitivity of the speed observation to electrical parameter variations and the observability of these parameters are studied, leading to the definition of the electrical parameter observation strategy. The testings on power bench, and in real application on a regional train, validate the performance of the speed sensorless drive proposed on the entire speed range, and its suitability to the constraints of a railway application.Le problème de la commande de machine asynchrone sans capteur mécanique de vitesse est très étudié dans les domaines de l'automatique et de l'électrotechnique. Ce travail porte sur la faisabilité de ce type de commande sur l'ensemble de la plage de vitesse et pour tout type de machine asynchrone afin d'être utilisée en traction ferroviaire. Une étude poussée de l'observabilité permet de définir une mesure quantitative continue de l'observabilité de la vitesse de la machine, appelée index d'observabilité. La synthèse d'un observateur confirme ainsi la correspondance entre les zones de faible index d'observabilité et celles où l'observation est de mauvaise qualité. L'index d'observabilité défini dans cette thèse permet donc de prédire les performances d'observation d'un système. L'originalité principale des travaux présentés tient dans l'utilisation de cet index d'observabilité dans la commande de la machine asynchrone sans capteur mécanique de vitesse. En tirant profit du degré de liberté qu'offre la variation d'amplitude du flux, nous proposons de garantir un index d'observabilité au-dessus d'un seuil tout en respectant les autres contraintes de la commande. L'observation de la vitesse devient alors précise sur toute la plage de vitesse, et un fonctionnement long est possible en tout point sans perturber le couple réalisé. Des expérimentations sur simulateur numérique viennent confirmer ces résultats, y compris lors de phases de patinage. L'observation des paramètres électriques est également étudiée afin de garantir la précision de l'observation de vitesse. Pour cela, la sensibilité de l'observation de vitesse aux variations de paramètres électriques et l'observabilité de ces paramètres sont étudiées, permettant de définir une nouvelle stratégie d'observation des paramètres électriques. Des essais sur banc de puissance, puis en application réelle sur un train régional, valident les performances de la commande sans capteur de vitesse proposée sur toute la plage de vitesse, et son adéquation aux contraintes d'une application ferroviaire

Induction machine speed sensorless drive : Application to electrica traction

Le problème de la commande de machine asynchrone sans capteur mécanique de vitesse est très étudié dans les domaines de l'automatique et de l'électrotechnique. Ce travail porte sur la faisabilité de ce type de commande sur l'ensemble de la plage de vitesse et pour tout type de machine asynchrone afin d'être utilisée en traction ferroviaire. Une étude poussée de l'observabilité permet de définir une mesure quantitative continue de l'observabilité de la vitesse de la machine, appelée index d'observabilité. La synthèse d'un observateur confirme ainsi la correspondance entre les zones de faible index d'observabilité et celles où l'observation est de mauvaise qualité. L'index d'observabilité défini dans cette thèse permet donc de prédire les performances d'observation d'un système. L'originalité principale des travaux présentés tient dans l'utilisation de cet index d'observabilité dans la commande de la machine asynchrone sans capteur mécanique de vitesse. En tirant profit du degré de liberté qu'offre la variation d'amplitude du flux, nous proposons de garantir un index d'observabilité au-dessus d'un seuil tout en respectant les autres contraintes de la commande. L'observation de la vitesse devient alors précise sur toute la plage de vitesse, et un fonctionnement long est possible en tout point sans perturber le couple réalisé. Des expérimentations sur simulateur numérique viennent confirmer ces résultats, y compris lors de phases de patinage. L'observation des paramètres électriques est également étudiée afin de garantir la précision de l'observation de vitesse. Pour cela, la sensibilité de l'observation de vitesse aux variations de paramètres électriques et l'observabilité de ces paramètres sont étudiées, permettant de définir une nouvelle stratégie d'observation des paramètres électriques. Des essais sur banc de puissance, puis en application réelle sur un train régional, valident les performances de la commande sans capteur de vitesse proposée sur toute la plage de vitesse, et son adéquation aux contraintes d'une application ferroviaire.The problem of speed sensorless control of induction machine is a well-studied problem in the field of automatic control and electrical engineering. This work addresses the problem of the feasibility of induction machine control over the whole speed range and for any type of induction machine, aiming at being used in a railway application. An intensive study of observability has defined a continuous quantitative measurement of the speed observability, named observability index. An observer was developped to confirme the correspondence between low-observability index areas and poor observation quality. The observability index defined in this thesis is thus a way to predict the observation performance of systems. The main originality of the work presented in this thesis is the use of this observability index in the induction machine speed sensorless drive. By taking advantage of the degree of freedom given by the variation of the flux amplitude, we propose to guarantee the observability index value above a given threshold while respecting the other constraints of the control. The speed observation becomes precise over the entire speed range, and a long time operation is possible on any point, without interfering with torque regulation. Experiments on real-time simulator confirm these results, including when slipping and sliding occurs. The electrical parameter observation is also studied to ensure the accuracy of speed observation. For this, the sensitivity of the speed observation to electrical parameter variations and the observability of these parameters are studied, leading to the definition of the electrical parameter observation strategy. The testings on power bench, and in real application on a regional train, validate the performance of the speed sensorless drive proposed on the entire speed range, and its suitability to the constraints of a railway application

Trends in global mineral and metal criticality: the need for technological foresight

International audienceSince the beginning of the third millennium, several trends, such as the rapid rise to global superpower status of China, with its 1.4 billion habitants; the transfer of large industrial production segments from West to East (Asia) and, more recently, of the growing political and trade tensions between the USA and China; the (re)birth of nationalisms, communitarianism and autocratic regimes; and minerals and metals industry–specific sustainability issues such as greenhouse gas emissions waste production and poor social acceptance of large-scale mining projects, are threatening the mineral and metal supplies of rich OECD countries that have depended on well-functioning free markets to supply their economies’ mineral and metal needs for the past few decades. These developments happen while demography, the growth of the global middle-class, urbanisation and, now, the need for a rapid transition to low-carbon energy production all concur to a further acceleration of the global demand for minerals and metals. This context leads governments and industries to pay much more attention to potential mineral supply/pricing issues, leading to the publication of mineral criticality studies, assessing the economic importance and supply risks related to specific minerals and metals, from the point of view of specific governments, economic sectors or industries. Some criticality assessments also propose future demand scenarios for selected minerals and metals, looking at the next decades, sometimes up to 2100. While these studies provide important information on current market conditions and issues, those looking at future supply and demand appear to insufficiently consider the probability of significant technology shifts that, if confirmed, would deeply impact on future demand scenarios. Three technology shifts that appear as highly probable (Li-metal batteries (including solid-state Li batteries); low/no neodymium-, praseodymium-, dysprosium- or terbium-containing permanent magnets; and composite matrix ceramics used in aircraft jet engines and gas turbines used for electricity and heat production) are highlighting the need to better integrate technology foresight in criticality assessments as such shifts are likely to have large impacts on the demand for some of the minerals and metals that are rated as highly critical in many studies (cobalt, dysprosium, graphite, neodymium, praseodymium, rhenium and tantalum), or for which demand scenarios are presented that may outstrip possible supply

Ecological assessment of Phragmites australis wetlands using multi-season SPOT-5 scenes

International audienceEcologists and conservationists need accurate and replicable tools for monitoring wetland conditions in order to develop and implement adaptive management strategies efficiently. The Rhone Delta (Camargue) in southern France encloses 9200 ha of fragmented reed marshes actively managed for reed harvesting, waterfowl hunting or cattle grazing, and holding significant numbers of vulnerable European birds. We used multi-season SPOT-5 data in conjunction with ground survey to assess the predictive power of satellite imagery in modelling indicators of reed structure (height, diameter, density and cover of green/dry stems) relevant to ecosystem management and bird ecology. All indicators could be predicted accurately with a combination of bands (SWIR, NIR) and indices (SAVI, OSAVI, NDWI, DVI, DVW, MSI) issued from scenes of March, June, July, September or December and subtraction between these. All models were robust when validated with an independent set of satellite and field data. The high spatial resolution of SPOT-5 scenes (pixel of 10 × 10 m) permits the monitoring of detailed attributes characterizing the reed ecosystem across a large spatial extent, providing a scientifically-based, replicable tool for managers, stakeholders and decision-makers to follow wetland conditions in the short and long-term. Combined with models on the ecological requirements of vulnerable bird species, these tools can provide maps of potential species ranges at spatial extents that are relevant to ecosystem functioning and bird populations