International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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The CISE-LOCEAN seawater isotopic database (1998-2021)
No full textInternational audienceThe characteristics of the CISE-LOCEAN seawater isotope dataset (δ18O, δ2H, referred to as δD) are presented (https://doi.org/10.17882/71186; Waterisotopes-CISE-LOCEAN, 2021). This dataset covers the time period from 1998 to 2021 and currently includes close to 8000 data entries, all with δ18O, three-quarters of them also with δD, associated with a date stamp, space stamp, and usually a salinity measurement. Until 2010, samples were analyzed by isotopic ratio mass spectrometry and since then mostly by cavity ring-down spectroscopy (CRDS). Instrumental uncertainty in this dataset is usually as low as 0.03 ‰ for δ18O and 0.15 ‰ for δD. An additional uncertainty is related to the isotopic composition of the in-house standards that are used to convert data to the Vienna Standard Mean Ocean Water (VSMOW) scale. Different comparisons suggest that since 2010 the latter have remained within at most 0.03 ‰ for δ18O and 0.20 ‰ for δD. Therefore, combining the two uncertainties suggests a standard deviation of at most 0.05 ‰ for δ18O and 0.25 ‰ for δD. For some samples, we find that there has been evaporation during collection and storage, requiring adjustment of the isotopic data produced by CRDS, based on d-excess (δD − 8×δ18O). This adjustment adds an uncertainty in the respective data of roughly 0.05 ‰ for δ18O and 0.10 ‰ for δD. This issue of conservation of samples is certainly a strong source of quality loss for parts of the database, and "small" effects may have remained undetected. The internal consistency of the database can be tested for subsets of the dataset when time series can be obtained (such as in the southern Indian Ocean or North Atlantic subpolar gyre). These comparisons suggest that the overall uncertainty of the spatially (for a cruise) or temporally (over a year) averaged data is less than 0.03 ‰ for δ18O and 0.15 ‰ for δD. However, 18 comparisons with duplicate seawater data analyzed in other laboratories or with other datasets in the intermediate and deep ocean suggest a larger scatter. When averaging the 18 comparisons done for δ18O, we find a difference of 0.082 ‰ with a standard error of 0.016 ‰. Such an average difference is expected due to the adjustments applied at LOCEAN to saline water data produced either by CRDS or isotope ratio mass spectrometry (IRMS), but the scatter found suggests that care is needed when merging datasets from different laboratories. Examples of time series in the surface North Atlantic subpolar gyre illustrate the temporal changes in water isotope composition that can be detected with a carefully validated dataset
Gunwale bobbing
No full textInternational audienceIt has been shown experimentally that small droplets, bouncing on a vibrated liquid bath, can "walk" across the surface due to their interaction with their own wave-field. Gunwale bobbing is a life-size instance of this phenomena in which a person standing on the gunwales of a canoe propels it by pumping it into oscillation with the legs. The canoe moves forward by surfing the resulting wave-field. After an initial transient, the canoe achieves a cruising velocity which satisfies a balance between the thrust generated from pushing downwards into the surface gradients of the wave-field and the resistance due to a combination of profile drag and wave drag. By superposing the linear wave theories of Havelock (1919) for steady cruising and of Helmholtz for an oscillating source, we demonstrate that such a balance can be sustained. We calculate the optimal parameter values to achieve maximum canoe velocity. We compare our theoretical result to accelerometer data taken from an enthusiastic gunwale bobber. We discuss the similarities and differences between gunwale bobbing and hydrodynamic quantum analogues, and possible applications to competitive sports
Proteomic analysis of neutrophils from COVID-19 patients
No full textInternational audienceNo abstract availabl
Silica-based fibers with axially aligned mesopores from chitin self-assembly and sol-gel chemistry
No full textInternational audiencePolysaccharide nanorods (chitin, cellulose) can be used as colloidal templates to form silica-based mesoporous materials by combining self-assembly and sol-gel chemistry. Chitin nanorods are chosen here for their self-assembly properties, facile preparation from natural resources, and because of the complexing properties of the free amino groups at their surface in view of further functionalization. Electrospinning of ethanolic co-suspensions, containing the chitin nanorods as pore templates, siloxane oligomers as silica precursors and polyvinylpyrrolidone (PVP) as spinning polymer, allows for forming mats of hybrid organic-inorganic fibers with diameters in the 200-300 nm range. The relative proportions of each component can be adjusted to meet specific characteristics (e.g. micro-/mesoporosity ratio). After calcination, the fibers present an open porosity studied by TEM and N2 volumetry. Elongated mesopores (100-200 nm long, 2-4 nm wide) are created by individual chitin monocrystals forming the nanorods. They are highly oriented along the fibers' axes with orientational order parameters P2 > 0.95 for volume chitin contents chitin* ≥ 0.2. Additional microporosity is provided by the removal of the spinning polymer, PVP. Complementary viscosity measurements on the initial cosuspensions allow discussing the interactions between colloids and their possible impact on the materials' textures observed. The introduction of a monomeric Ti 4+ precursor in the co-suspensions leads to isolated and tetrahedral Ti units, distributed in the calcined porous silica fibers and possibly close to the pores surface. In addition, preliminary investigations on processing the fibers with a Zn xanthate as ZnS precursor leads to carbonized fibers with nanoparticles and a Zn/S molar ratio close to 1
Identification des polluants naturels et anthropiques dans la zone transfrontalière de Saint Georges de l'Oyapock pour une modélisation et un suivi futurs de ces polluants par SIG
No full textInternational audienceLike other communes in French Guiana, the commune of Saint-Georges de l'Oyapock is subjected each year to natural pollutants (e.g. Saharan dust, Prospero et al. 1981) and to anthropogenic pollutants (e.g. benzene).Given that the measuring stations of PM10, PM2.5, nitrogen oxide and benzene belonging to ATMO GUYANE currently exist only on Cayenne, Matoury and Kourou, a preliminary study had to be carried out here for desert aerosols at first, then for benzene. In the case of desert aerosols, a first work on the search for correlation between ground data collected by Thermo Scientific Tapered Element Oscillating Microbalance (TEOM) and optical thickness data (AOT) from satellite VIIRS images was carried out. In the case of benzene, the very first measurement campaign was carried out at the end of June 2021 just before the closing of schools. For the OHM Oyapock, establishing a recurrent benzene measurement campaign over the medium term would be a tool to evaluate internal mobilities in Saint-Georges and Oiapoque as well as cross-border mobilities inherent to the opening of the bridge. The results will be presented here but it will be necessary to repeat this campaign in full school period. The goal in the short or medium term is to evaluate the impacts on health. For this, according to WHO recommendations for population health, we have chosen a threshold of 50 ?g m-3. In fact, values greater than 50 ?g.m-3 are harmful to populations.Comme d'autres communes de Guyane, la commune de Saint-Georges de l'Oyapock est soumise chaque année à des polluants naturels (ex : poussières sahariennes, Prospero et al. 1981) et à des polluants anthropiques (ex : benzène). Etant donné que les stations de mesure des PM10, PM2.5, oxyde d'azote et benzène appartenant à ATMO GUYANE n'existent actuellement que sur Cayenne, Matoury et Kourou, une étude préliminaire a dû être réalisée ici pour les aérosols désertiques dans un premier temps, puis pour le benzène. Dans le cas des aérosols désertiques, un premier travail de recherche de corrélation entre les données au sol collectées par la Thermo Scientific Tapered Element Oscillating Microbalance (TEOM) et les données d'épaisseur optique (AOT) issues des images du satellite VIIRS a été réalisé. Dans le cas du benzène, la toute première campagne de mesure a été réalisée à la fin du mois de juin 2021, juste avant la fermeture des écoles. Pour l'OHM Oyapock, la mise en place d'une campagne de mesure récurrente du benzène sur le moyen terme serait un outil d'évaluation des mobilités internes à Saint-Georges et à Oiapoque ainsi que des mobilités transfrontalières inhérentes à l'ouverture du pont. Les résultats seront présentés ici mais il sera nécessaire de renouveler cette campagne en pleine période scolaire. L'objectif à court ou moyen terme est d'évaluer les impacts sur la santé. Pour cela, selon les recommandations de l'OMS pour la santé des populations, nous avons choisi un seuil de 50 ?g m-3. En effet, des valeurs supérieures à 50 ?g.m-3 sont néfastes pour les populations
La lecture à haute voix, une interprétation personnelle du texte littéraire
No full textThis thesis is part of the second year of the second degree MEEF master's degree in modern literature. Starting from the observation that pupils have more and more difficulty reading a text aloud, and that consequently pupils are reluctant to read aloud in class, this study aims to see the reasons for this reluctance, but also to see how to improve students' reading aloud. Consequently, several hypotheses are put forward and it is a question of confirming them or not: reading aloud implies that the text read is understood by the student, so it is necessary to do linear reading before this reading aloud to remove any ambiguities in the text. Students with difficulties and reluctance to read are due to anxieties about speaking. It will there fore be a question of working on eloquence and the very definition of expressive reading to understand the expectations of the exercise. The thesis is divided into four parts: it sets out the key terms and concepts for understanding all the subtleties of reading aloud, then it will be a question of making a study of different activities carried out to work on reading aloud and to see whether these activities were conclusive and why, in order to confirm or not the hypotheses preceding this study.Ce mémoire s’inscrit dans le cadre de la seconde année du master MEEF second degré, en lettres modernes. En partant du constat que les élèves ont de plus en plus de difficulté à lire un texte à haute voix, et que par conséquent les élèves sont réticents à lire à haute voix en classe, il s’agit dans cette étude de voir les raisons de cette réticence, mais aussi de voir comment améliorer la lecture à haute voix des élèves. Par conséquent, plusieurs hypothèses sontavancées et il s'agit de les confirmer ou non : la lecture à haute voix implique que le texte lu soit compris par l’élève, donc il faut faire la lecture linéaire en amont de cette lecture à haute voix pour lever toutes les ambiguïtés du texte. Les élèves ayant des difficultés et réticences à lire sont dues à des angoisses face à la prise de parole à l’oral. Il s’agira donc de travailler sur l’éloquence et la définition même de lecture expressive pour comprendre les attentes de l’exercice. Le mémoire se subdivise en quatre temps : il expose les termes et notions clés pour comprendre toutes les subtilités de la lecture à haute voix, puis il s’agira de faire une étude de différentes activités menées pour travailler la lecture à haute voix et de voir si ces activités ont été concluantes et pourquoi, afin de confirmer ou non les hypothèses précédant cette étude
Dissolution par divorce d'un mariage bigame conclu à l'étranger
No full textInternational audience(Civ. 1re, 17 novembre 2021, no 20-19.420, F-B, D. 2022. 389, note F. Jault-Seseke ; ibid. 764, obs. J.-J. Lemouland et D. Vigneau ; JDI 2022, comm. 2, J. Guillaumé ; D. actu., 23 nov. 2021, obs. F. Mélin ; Dr. fam. 2022, comm. 25, obs. C. Bois-Farinaud et M. Poncet ; JCP 2021, 1290, obs. C. Reitzer) - Cour de cassation (1re civ.), 17 novembre 2021, no 20-19.42
Evaluation du maintien des arbovirus dans la nature via les moustiques Aedes par la théorie des semi-groupes positifs
No full textInternational audienceFor more than one century, Aedes species are supposed to be a reservoir in dengue, yellow fever, rift valley fever and west nile viruses transmission. In this article, we study an infinite dimension ordinary differential equations system that models arbovirus vertical transmission in \textit{Aedes} mosquito. Relying of the positive semigroup theory, we show that the model is well-posed and compute a threshold parameter known as the basic reproduction ratio . This parameter describes "the average rate of secondary new cases of infected adult females from emergences in a breeding habitat that are produced by an infected adult female via transovarial transmission during its lifetime." In addition, we prove that the solution of the model goes to zero asymptotically if R0<1$, else it has the property of balanced exponential growth. Finally, a climate-environment effects Index on model parameters and a diagram depicting the conditions of arboviruses persistence via Aedes in nature is derived.Depuis plus d'un siècle, certaines espèces Aedes sont supposées jouer un rôle de réservoir de virus dans les épidémies de la dengue, de la fièvre jaune, de la fièvre de la vallée du Rift et du Nil occidental. Dans cet article, nous étudions un système différentiel de dimension infinie décrivant la transmission verticale des arbovirus chez les moustiques Aedes. Grâce à la théorie des semi-groupes positifs, nous avons montré que le modèle est bien pos\'e et extrait un paramètre seuil appelé taux de reproduction de base R0. Ce paramètre R0 décrit " le taux moyen de cas secondaires d'infection des femelles adultes émergentes dans un habitat de reproduction à partir d'oeufs contaminés via la transmission transovarienne et pondus par une femelle adulte durant sa vie". De plus, nous avons démontré que la solution du modèle tend vers zéro quand t tend vers l'infini si R0<1, sinon il possède la propriété de croissance exponentielle asynchrone. Enfin, ce résultat permet de proposer un indice de mesure des effets climatiques et environnementaux sur les paramètres du modèle et un diagramme décrivant les conditions de maintien des arbovirus dans la nature chez les Aedes
Les ONG et le droit international des changements climatiques
No full textLes organisations non gouvernementales, en sigle ONG, sont des acteurs qui ont leur place dans le droit international des changements climatiques au même titre que les Etats et les organisations publiques internationales. Cette place a été conquise à la suite de durs efforts. C'est pourquoi, désormais, ces ONG, grâce à leur participation à l'élaboration des normes environnementales relatives au climat ainsi qu'à leur implication sur le terrain où prévalent les effets de ces changements climatiques, prouvent jour après jour qu'elles ont, dorénavant, un rôle incontournable dans la matérialisation de ce droit
Can Weathering of Banded Iron Formations Generate Natural Hydrogen? Evidence from Australia, Brazil and South Africa
No full textInternational audienceOxidation of iron-rich rock is known to generate H2 in oceanic as well as in continental domains. Here we tested the possibility of H2 generation as the result of weathering of banded iron formations (BIF). The BIF constitute more than 60% of global iron ore reserves with low Fe3+/Fetot and total Fe ranging from 20 to 40 wt% and are therefore good candidates for H2 production potential. In the vicinity of BIF-hosted iron mines in Australia, Brazil and South Africa, satellite imaging has revealed the presence of sub-circular depressions that usually are the proxy of H2-emitting features. A morphological comparison of the sub-circular depressions with the ones observed in previous studies point to probable H2 seeping in these areas. In parallel, a petrological study conducted on altered and fresh BIF samples from the Hamersley Province in Western Australia also suggests H2 generation during BIF weathering. Indeed, mineral transitions from ferrous silicate (riebeckite and/or minnesotaite) to ferric iron oxi-hydroxides (goethite) or from ferrous and ferric oxides (magnetite) to exclusively ferric oxides (maghemite, hematite, goethite) were observed on the samples. The oxidation of ferrous iron by aqueous fluids circulating through and leaching the BIF is promising for H2 generation. The BIF weathering profile suggests that the limiting factor is the presence of water, and that this reaction is happening at, or near, surface temperature. This challenges the idea that high temperatures are required to generate H2 as it is the case during the serpentinization. The link between BIF and H2 will have however to be further investigated to better constrain the reactions and their kinetics