L'énumération dans la copie

Nous nous sommes interrogées sur les difficultés rencontrées par les élèves dans la tâche de copie. Nous avons tenté de déterminer le rôle de l’énumération dans la copie ; pour cela, nous avons mis en place une expérimentation qui nous a permis de mettre en avant les stratégies adoptées par quelques élèves issus d’une classe de CE1

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Comparaison de l’effet de la fertilisation azotée sur la croissance et la fixation symbiotique de dix espèces de légumineuses

National audiencevoir pd

Fixation symbiotique de l’azote et effet précédent : toutes les légumineuses à graines se valent-elles ?

Prod 2019-81EAéquipe BAPéquipe SPEGESTADGEAPSIAGROSUPINRADOCTLegumes should play a key role in the transition towards a more sustainable agriculture by allowing areduction of nitrogen inputs due to their specific properties relative to the nitrogen cycle. However, thereis a lack of references for a wide diversity of species regarding their agronomic performances and thenitrogen fluxes they induce. A comparative study on ten grain legumes was conducted to i) quantitysymbiotic nitrogen fixation, ii) evaluate its response to inorganic soil nitrogen, and iii) quantify the effectof legumes on the yield of the subsequent wheat (unfertilised) as related to the N mineralisation of theircrop residues. For nine species out of ten, symbiotic fixation was able to ensure plant growth andnitrogen acquisition at levels similar to those achieved by nutrition based on inorganic nitrogen.Differences in symbiotic fixation inhibition were observed and were partially explained by differences ininorganic nitrogen uptake efficiency among species. Those differences were related to differences inroot lateral expansion rate among species. The great majority of legumes led to higher wheat yieldscompared to those of wheat cultivated after cereals. Wheat yield variability was partially related todifferences in crop residue nitrogen mineralisation among species according to their carbon /nitrogen ratio. However, nitrogen supplied to the soil by legumes can be lost during the fallow period beforenitrogen is retrieved by the subsequent crop. This risk increases with legumes harvested in summer vs.beginning of autumn, because of a longer fallow period.Les légumineuses ont un rôle majeur à jouer dans la transition vers une agriculture plus durable, en réduisant notamment le recours aux intrants azotés du fait de leurs propriétés spécifiques vis-à-vis du cycle de l’azote. Pourtant peu de références sont disponibles pour une diversité d’espèces quant à leurs performances agronomiques et aux flux d’azote qu’elles induisent. Une étude comparative sur dix espèces de légumineuses à graines a été menée afin i) de quantifier la fixation symbiotique, ii) d’évaluer sa réponse à la présence d’azote minéral du sol, et iii) de quantifier l’effet des légumineuses sur le rendement d’un blé suivant (non fertilisé) en lien avec la minéralisation de leurs résidus de culture. Pour neuf espèces sur dix la fixation symbiotique a permis d’assurer une croissance et une nutrition azotée des plantes aussi bonnes qu’avec une nutrition basée sur le prélèvement d’azote minéral. Des différences d’inhibition de la fixation symbiotique par l’azote minéral ont été mises en évidence et ont été partiellement expliquées par des différences d’efficience de prélèvement de l’azote minéral entre les espèces. Ces différences ont été corrélées à des différences de vitesse d’expansion latérale des racines entre les espèces. La grande majorité des légumineuses a engendré des rendements de blé supérieurs à ceux de blés cultivés après des céréales. La variabilité des rendements du blé a en partie pu être reliée à la minéralisation de l’azote des résidus, variable entre espèces selon leur rapport carbone / azote. Cependant l’azote fourni au sol par les légumineuses peut être perdu pendant la période d’interculture, avant que cet azote ne soit prélevé par la culture suivante. Ce risque augmente pour les espèces de légumineuses récoltées en été contrairement au début automne, du fait d’une interculture plus longue. Abstract: Symbiotic nitrogen fixation and pre-crop effect : are all grain legumes the same? Legumes should play a key role in the transition towards a more sustainable agriculture by allowing a reduction of nitrogen inputs due to their specific properties relative to the nitrogen cycle. However, there is a lack of references for a wide diversity of species regarding their agronomic performances and the nitrogen fluxes they induce. A comparative study on ten grain legumes was conducted to i) quantity symbiotic nitrogen fixation, ii) evaluate its response to inorganic soil nitrogen, and iii) quantify the effect of legumes on the yield of the subsequent wheat (unfertilised) as related to the N mineralisation of their crop residues. For nine species out of ten, symbiotic fixation was able to ensure plant growth and nitrogen acquisition at levels similar to those achieved by nutrition based on inorganic nitrogen. Differences in symbiotic fixation inhibition were observed and were partially explained by differences in inorganic nitrogen uptake efficiency among species. Those differences were related to differences in root lateral expansion rate among species. The great majority of legumes led to higher wheat yields compared to those of wheat cultivated after cereals. Wheat yield variability was partially related to differences in crop residue nitrogen mineralisation among species according to their carbon /nitroge

Comparative effect of inorganic N on plant growth and N2 fixation of ten legume crops

National audienc

Impact of pea genetic variability on the control of N2O reduction by soil-microorganisms-plant systems

National audienc

N2O emissions during and after legume crops cultivation

International audienc