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L'Arbre du savoir Apprendre: Vers un référentiel cognitif
No full textInternational audienceI, for one, am convinced that the essential role of all the educational actors, through a genuine presence to each other, is to enable the emergence of personal inquiry which contributes to the opening up of our learning space. It also sets in motion the co-actors, the learner and those who accompany that learner toward a place where it is possible to actualize their own potential.… If inquiry is the true sap of the tree of knowledge, the different actors in the educational setting can no longer do without it on their own journey.Je suis, pour ma part, convaincue que le rôle essentiel du monde éducatif dans son ensemble est de permettre, par une véritable présence, l’émergence chez tous les partenaires de la situation d’apprentissage, de leur propre questionnement qui ouvre l’espace intérieur sur notre capacité matricielle, celui qui met en mouvement les co-acteurs, la personne en formation et ceux qui l’accompagnent, vers un lieu où il leur est possible d’actualiser leur potentiel.… Si le questionnement est la véritable sève de l’arbre du savoir-apprendre, les différents acteurs de la situation de formation ne peuvent plus en faire l’économie pour leur propre parcours
Pheromone Receptor Knock-Out Affects Pheromone Detection and Brain Structure in a Moth
No full textInternational audienceSex pheromone receptors are crucial in insects for mate finding and contribute to species premating isolation. Many pheromone receptors have been functionally characterized, especially in moths, but loss of function studies are rare. Notably, the potential role of pheromone receptors in the development of the macroglomeruli in the antennal lobe (the brain structures processing pheromone signals) is not known. Here, we used CRISPR-Cas9 to knock-out the receptor for the major component of the sex pheromone of the noctuid moth Spodoptera littoralis, and investigated the resulting effects on electrophysiological responses of peripheral pheromone-sensitive neurons and on the structure of the macroglomeruli. We show that the inactivation of the receptor specifically affected the responses of the corresponding antennal neurons did not impact the number of macroglomeruli in the antennal lobe but reduced the size of the macroglomerulus processing input from neurons tuned to the main pheromone component. We suggest that this mutant neuroanatomical phenotype results from a lack of neuronal activity due to the absence of the pheromone receptor and potentially reduced neural connectivity between peripheral and antennal lobe neurons. This is the first evidence of the role of a moth pheromone receptor in macroglomerulus development and extends our knowledge of the different functions odorant receptors can have in insect neurodevelopment
The Theory of Mathematical Working Spaces in Brief
No full textInternational audienceThis chapter contains an overview of the main points of the theory of MWS in relation to frequently asked questions. The aim is to form the basis of an online glossary of the theory, to be completed according to the contributions of researchers
The causes of the selection of biological nitrification inhibition (BNI) in relation to ecosystem functioning and a research agenda to explore them
No full textInternational audienceBiological nitrification inhibition (BNI) has already led to several studies mainly focused on underlying molecular mechanisms and applications to agriculture. We argue that it is also important to study BNI more systematically from the ecological and evolutionary points of view to understand its implications for plants and soil nitrifiers as well as its consequences for ecosystems. Therefore, we propose here a dedicated research agenda identifying the most critical research questions: (1) How is BNI distributed across plant phylogeny and why has it been selected? (2) What are the costs-to-benefits balance of producing BNI compounds and the relative impacts on BNI evolution? (3) Can we understand the evolutionary pressures leading to BNI and identify the environmental conditions favorable to BNI plants? (4) How has BNI coevolved with plant preference for ammonium vs. nitrate? (5) Diverse BNI compounds and various inhibition mechanisms have been described, but implications of this diversity are not understood. Does it allow inhibition of various groups of nitrifiers? (6) Does this diversity of BNI compounds increase the efficiency, spatial extension, and duration of BNI effect? (7) What are the impacts of BNI compounds on other soil functions? (8) Can field experiments, coupled to scanning of the diversity of BNI capabilities within plant communities, evaluate whether BNI influences plant-plant competition and plant coexistence? (9) Can field quantification of various nitrogen (N) fluxes assess whether BNI lead to more efficient N cycling with lower losses and hence increased primary production? (10) Can the impact of BNI on N budgets and climate (through its impact on N2O emissions and its indirect impact on carbon budget) be evaluated at the regional scale? We discuss why implementing this research program is crucial both for the sake of knowledge and to develop applications of BNI for agriculture
Short-term assessment of the effect of phytostabilizing plants and management methods on the biodiversity and the mobility of trace elements in an urban wasteland in the Région Ile-de-France, France
No full textCurrent urban development guidelines favour renewal and densification of cities, emphasizing the necessity to redevelop urban wastelands. However, many such sites are polluted with heavy metals and metalloids (TE), radionuclides, hydrocarbons. As a result, wasteland reconversion implies initial soil decontamination. The cost of servicing, depolluting and decontaminating these wastelands, using conventional soil depollution techniques is exorbitant. Thus, phytotechnology techniques offer an alternative that is more in line with sustainable development issues (Bert et al. 2012). Although the latter have been extensively studied for more than 30 years, they are still emerging on the market for the treatment of polluted sites. In addition, they raise many unanswered questions on the mobility, bioavailability and transfer of pollutants between the different compartments (soil/water/plants/microflora/fauna) over a relatively long periods of time (more than 10 years). Also,&#160;&#160; maintenance and management practices on site during the process of depollution still are problematic, particularly the downstream usage of contaminated plant biomass.</p><p>Through the OBSOLU project (Urban Observatory for the Study of Anthropogenic Soils), the Val-de-Marne Departmental Council (CD94) wishes to evaluate new experimental approaches for the rehabilitation of an urban wasteland affected by multi-metallic pollution (La Pierre-Fitte site, Villeneuve-le-Roi, Val-de-Marne, France). The &#160;evaluation of the dynamics of metallic trace elements (TE) in the soil-water-plant-fauna continuum is carried out on four vegetated plots (planted either with native or introduced phytostabilizing plant species (<em>Agrostis capillaris, Festuca arundinacea, Lolium perenne</em>)) managed according to two different methods (harvested plant biomass either left in place &#160;or exported for composting). &#160;The objective is to assess over several years, the mobility of TE in the soil and their infiltration to the water table, in relation with 1) the presence of native or phytostabilizing plants, mycorrhizal or not, 2) of the type of management of the harvested plant biomass and 3) the biodiversity indices at the experimental sites. Initial TE analyses revealed the presence of lead, zinc, copper and nickel in high concentrations, distributed heterogeneously over the entire experimental site. Interestingly, one year into the experiment, this high level of pollution with TE does not seem to affect the plant and arthropod populations that show good biodiversity indices, compared to other polluted sites in Ile-de-France. All introduced phytostabilizing plant species surveyed were found to be mycorrhizal and phytostabilizing for lead, nickel and to a lesser extent copper. So did certain native species, such as <em>Solidago canadensis</em>. Only zinc, an acknowledged mobile element, does not seem to be stabilized in the rhizosphere of the plants, either native or introduced. At this point in this five-year long experiment, a detailed analysis of the initial characteristics of the site has been established. The preliminary results indicate that phytostabilization could be limit TE dispersal in the environment, a conclusion that will be reassessed over the years. ;Key word : metallic trace elements - phytostabilisation - urban wasteland - rehabilitation</p>
Time spent in a ball by a critical branching random walk
No full textWe study a critical branching random walk on Z d. We focus on the tail of the time spent in a ball, and our study, in dimension four and higher, sheds new light on the recent result of Angel, Hutchcroft and Jarai [AHJ21], in particular on the special features of the critical dimension four. Finally, we analyse the number of walks transported by the branching random walk on the boundary of a distant ball. Keywords and phrases. Branching random walk; local times; range. MSC 2010 subject classifications. Primary 60G50; 60J80
Topology optimization for enhanced dynamic fracture resistance of structures
No full textInternational audienceA topology optimization framework for improving the dynamic fracture resistance of structures is proposed. The phase field method for fracture is combined with Solid Isotropic Material with Penalization (SIMP) topology optimization. The topology optimization problem is defined as minimizing the fracture energy during the whole dynamic loading process, from initiation of cracks to full failure of the structure, under volume and compliance constraints. Semi analytical expressions of sensitivities in a dynamic context are provided to solve the topology optmization problem efficiently. Numerical examples involving structures subjected to impact loading are investigated. It is shown that the present framework allows a significant reduction of the fracture energy as compared to designs obtained by static optimization
The Debate on Super-quantum Correlations: Statistical Misinterpretation and Logical Fallacy
No full textInternational audienc
Compilation of 29 years of postmortem examinations identifies major shifts in equine parasite prevalence from 2000 onwards
No full textInternational audienceHorses are infected by a wide range of parasite species that form complex communities. Parasite control imposes significant constraints on parasite communities whose monitoring remains however difficult to track through time. Postmortem examination is a reliable method to quantify parasite communities. Here, we compiled 1,673 necropsy reports accumulated over 29 years, in the reference necropsy centre from Normandy (France). The burden of non-strongylid species was quantified and the presence of strongylid species was noted. Details of horse deworming history and the cause of death were registered. Building on these data, we investigated the temporal trend in non-strongylid epidemiology and we determined the contribution of parasites to the deaths of horses throughout the study period. Data analyses revealed the seasonal variations of non-strongylid parasite abundance and reduced worm burden in race horses. Beyond these observations, we found a shift in the species responsible for fatal parasitic infection from the year 2000 onward, whereby fatal cyathostominosis and Parascaris spp. infection have replaced cases of death caused by S. vulgaris and tapeworms. Concomitant break in the temporal trend of parasite species prevalence was also found within a 10-year window (1998-2007) that has seen the rise of Parascaris spp. and the decline of both Gasterophilus spp. and tapeworms. A few cases of parasite persistence following deworming were identified that all occurred after 2000. Altogether, these findings provide insights into major shifts in non-strongylid parasite prevalence and abundance over the last 29 years. They also underscore the critical importance of Parascaris spp. in young equids
