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An ecosystem-based approach to assess the status of Mediterranean algae-dominated shallow rocky reefs
No full textInternational audienc
Analysing trends and forecasting malaria epidemics in Madagascar using a sentinel surveillance network: a web-based application
No full textInternational audienceBackground : The use of a malaria early warning system (MEWS) to trigger prompt public health interventions is a key step in adding value to the epidemiological data routinely collected by sentinel surveillance systems. Methods : This study describes a system using various epidemic thresholds and a forecasting component with the support of new technologies to improve the performance of a sentinel MEWS. Malaria-related data from 21 sentinel sites collected by Short Message Service are automatically analysed to detect malaria trends and malaria outbreak alerts with automated feedback reports. Results : Roll Back Malaria partners can, through a user-friendly web-based tool, visualize potential outbreaks and generate a forecasting model. The system already demonstrated its ability to detect malaria outbreaks in Madagascar in 2014. Conclusion : This approach aims to maximize the usefulness of a sentinel surveillance system to predict and detect epidemics in limited-resource environments
Cognitive Performance Enhancement Induced by Caffeine, Carbohydrate and Guarana Mouth Rinsing during Submaximal Exercise
No full textInternational audienceThe aim of this study was to investigate the influence of serial mouth rinsing (MR) with nutritional supplements on cognitive performance (i.e., cognitive control and time perception) during a 40-min submaximal exercise. Twenty-four participants completed 4 counterbalanced experimental sessions, duringwhich they performed MR with either placebo (PL), carbohydrate (CHO: 1.6 g/25mL), guarana complex (GUAc: 0.4 g/25 mL) or caffeine (CAF: 67 mg/25 mL) before and twice during exercise. The present study provided some important new insights regarding the specific changes in cognitive performance induced by nutritional supplements. The main results were: (1) CHO, CAF and GUA MR likely led participants to improve temporal performance; (2) CAF MR likely improved cognitive control; and (3) CHO MR led to a likely decrease in subjective perception of effort at the end of the exercise compared to PL, GUA and CAF. Moreover, results have shown that performing 40-min submaximal exercise enhances information processing in terms of both speed and accuracy, improves temporal performance and does not alter cognitive control. The present study opens up new perspectives regarding the use of MR to optimize cognitive performance during physical exercise
Ancestral alliances: Plant mutualistic symbioses with fungi and bacteria
No full textWithin the plant microbiota, mutualistic fungal and bacterial symbionts are striking examples of microorganisms playing crucial roles in nutrient acquisition. They have coevolved with their hosts since initial plant adaptation to land. Despite the evolutionary distances that separate mycorrhizal and nitrogen-fixing symbioses, these associations share a number of highly conserved features, including specific plant symbiotic signaling pathways, root colonization strategies that circumvent plant immune responses, functional host-microbe interface formation, and the central role of phytohormones in symbiosis-associated root developmental pathways. We highlight recent and emerging areas of investigation relating to these evolutionarily conserved mechanisms, with an emphasis on the more ancestral mycorrhizal associations, and consider to what extent this knowledge can contribute to an understanding of plant-microbiota associations as a whole
Microbial Partnerships of Pathogenic Oomycetes
No full textMicrobial Partnerships of Pathogenic Oomycete
Habitat degradation increases stress-hormone levels during the breeding season, and decreases survival and reproduction in adult common lizards
No full textThe allostatic load model describes how individuals maintain homeostasis in challenging environment and posits that costs induced by a chronic perturbation (i.e., allostatic load) are correlated to the secretion of glucocorticoids, such as corticosterone. Habitat perturbations from anthropogenic activities are multiple and functional responses to those are still unclear. Here, we manipulated the habitat quality in 24 semi-natural populations of the common lizard during 1 year. We tested the predictions of the allostatic load model that habitat degradation should increase baseline corticosterone levels, and should induce concomitant physiological changes, such as lipid mobilization and lower immunocompetence, and demographic changes, such as lower body growth, survival and/or reproductive performances. Our results highlight stage-dependent effects of habitat degradation on physiological traits during the breeding season: adult lizards had higher baseline corticosterone levels and yearling lizards had a lower inflammatory response than adults, whereas juveniles had higher circulating lipid levels than yearlings and adults without concomitant change in corticosterone levels. In addition, habitat degradation reduced the performances of adults but not of juveniles: in low habitat quality populations, adult males had a lower survival and females had a smaller fecundity. These results are in accordance with the allostatic load model given that allostatic load was detected only during the season and in life stages of maximal energy expenditure. This underlines the importance to account for individual energy requirements to better understand demographic responses to habitat perturbation
Imagerie optique à très haut contraste : une approche instrumentale optimale
No full textThis thesis aims to optimize high-contrast imaging performance in visible and near infrared for exoplanet detection. The main study focuses on high-contrast at small separation, to image exoplanets in their habitable zone. This direct detection is achievable with the next Extremely Large Telescopes and with the development of coronagraph providing high performance at small separation. The approach adopted for this study creates a high-contrast region (a dark hole) with the combination of coronagraphy and wavefront shaping (wavefront control of both phase and amplitude with 2 deformable mirrors) but is limited by the Fresnel propagation of phase aberrations. The goal of this work is to define the wavefront shaping limitation in optical configuration (deformable mirrors location, component optical quality, beam diameter). A semi-analytic approach followed by a Monte-Carlo analysis of numerical end-to-end simulations is studied, resulting in the definition of the optimal configuration. Results are then applied to SPEED, a test bench to optimize and test high-contrast imaging at small separation with a segmented pupil. Another aspect of this thesis is a contribution to a stability study to treat the temporal stability as a crucial parameter in high-contrast imaging instrumentation, at the conception level. A preliminary work is initiated during the thesis to analyse the stability of the measuring instrument itself. A metrology tool and its thermal behaviour are thus studied. Finally, the last part of this thesis is a performance analysis of a new differential imaging technique, developed to improve high contrast with observations with different diaphragm sizes.Cette thèse vise à investiguer des moyens d'optimiser les performances de l'imagerie à haut contraste dans l'optique et le proche infrarouge pour la détection d'exo-planètes. L'étude principale a été menée sur le contraste à faible séparation permettant l'imagerie d'exo-planètes dans leur zone habitable. Cette détection directe est rendue possible par le développement des futurs grands télescopes et de coronographes de plus en plus performants à faible séparation. L'approche retenue permet de créer une zone sombre à haut contraste grâce à la coronographie et au « wavefront shaping » (contrôle de l'amplitude et de la phase avec 2 miroirs déformables), mais qui est limité par les effets de propagation de Fresnel. Les résultats obtenus ont déterminé les limitations de configuration optique pour le « wavefront shaping ». Grâce à une approche semi-analytique soutenue par des simulations numériques et une approche Monte-Carlo, ces limitations ont été analysées et quantifiées pour extraire les configurations optimales. Les résultats ont été appliqués au banc SPEED dont l'objectif est d'optimiser et de tester le haut contraste à faible séparation. Une deuxième étude a été une contribution à une étude générale de stabilité, en traitant la stabilité temporelle comme un paramètre indispensable dans la conception en amont d'instrument haut contraste. Un travail préliminaire a été initié sur la stabilité des instruments de mesure eux-mêmes à travers l'étude thermique d'un système de métrologie. Enfin, un dernier volet a été une étude de simulation de performances d'un nouveau concept d'imagerie différentielle basé sur l'acquisition d'images réalisées avec différentes tailles de pupilles
The Potential of Imaging from Ultra-Light Aircraft for Urban Tree Inventories: Case Study in Kaunas, Lithuania
No full textInternational audienceThe presentation is aimed to introduce imaging system based on simultaneous use of frame-type Rikola hyperspectral and RGB/CIR cameras applied for inventories and monitoring of urban green spaces. The system is run from a manned ultra-light aircraft, equipped for aerial photography missions. An aerial imaging campaign over the city of Kaunas, Lithuania was carried-out in summer of 2015 and 2016, acquiring narrow-bands measurements in the 500-900 nm spectral domain at 16 and 60 bands respectively, with a full width at half maximum ~10 nm. Simultaneously, aerial images were shot using Nikon D800E camera, converted and reconfigured to capture in NIR, Red+NIR and Green+NIR bands. Several methodological solutions for image calibration, co-registering of separate image bands, atmospheric correction and photogrammetric processing are investigated. Information available from the inventory of green spaces in Kaunas city was used to guide the selection of trees for identification studies and validation. Six urban deciduous tree species were separated using tree crown level statistics, extracted from 16 visible-near infrared spectral bands hyperspectral images, and discriminant analyses with an overall classification accuracy of 63.1 %. Fusion of hyperspectral and color-infrared images increased the classification accuracy by 3%. The identification accuracy of three tree health condition classes ranged from poor to moderate. The influence of increased number of hyperspectral bands on tree species ability as well as more advanced image processing solutions will be tested using materials from year 2016 campaign. The presentation will also discuss the potential of combining images from different platforms, ranging from unmanned aerial vehicles to space satellite systems, including the technological and economic reasoning
A general iterative imputation scheme with feedback control for tensor completion (IFCTC)
No full textNational audienceTensors and tensor decompositions are very useful mathematical tools for representing and analyzing multidimensional data. The problem of estimating missing data in a tensor of measurements, named tensor completion, plays an important role in numerous applications. In this paper, to solve this problem, we propose a general iterative imputation scheme including a first-order feedback mechanism, aiming to improve algorithm performance. Two particularizations of this scheme, in which we apply soft and hard thresholding operators based on the Tucker model, are discussed. Then, simulation results are presented to illustrate their performance.Les tenseurs et les décompositions tensorielles constituent des outils mathématiques très utiles pour représenter et analyser des données multidimensionnelles. Le problème de l'estimation de données manquantes dans un tenseur de mesures joue un rôle important dans de nombreuses applications. Dans cet article, nous proposons un schéma d'imputation général itératif incluant un mécanisme de rétroaction du premier ordre, avec l'objectif d'améliorer la performance de l'algorithme. Deux cas particuliers de ce schéma, faisant intervenir des opérateurs de seuillage doux et dur basés sur le modèle de Tucker, sont discutés. Puis, des résultats de simulations sont présentés pour illustrer leur performance