International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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Detection of the tidal deformation of WASP-103b at 3 σ with CHEOPS
No full textInternational audienceContext. Ultra-short period planets undergo strong tidal interactions with their host star which lead to planet deformation and orbital tidal decay. Aims: WASP-103b is the exoplanet with the highest expected deformation signature in its transit light curve and one of the shortest expected spiral-in times. Measuring the tidal deformation of the planet would allow us to estimate the second degree fluid Love number and gain insight into the planet's internal structure. Moreover, measuring the tidal decay timescale would allow us to estimate the stellar tidal quality factor, which is key to constraining stellar physics. Methods: We obtained 12 transit light curves of WASP-103b with the CHaracterising ExOplanet Satellite (CHEOPS) to estimate the tidal deformation and tidal decay of this extreme system. We modelled the high-precision CHEOPS transit light curves together with systematic instrumental noise using multi-dimensional Gaussian process regression informed by a set of instrumental parameters. To model the tidal deformation, we used a parametrisation model which allowed us to determine the second degree fluid Love number of the planet. We combined our light curves with previously observed transits of WASP-103b with the Hubble Space Telescope (HST) and Spitzer to increase the signal-to-noise of the light curve and better distinguish the minute signal expected from the planetary deformation. Results: We estimate the radial Love number of WASP-103b to be hf = 1.59−0.53+0.45. This is the first time that the tidal deformation is directly detected (at 3 σ) from the transit light curve of an exoplanet. Combining the transit times derived from CHEOPS, HST, and Spitzer light curves with the other transit times available in the literature, we find no significant orbital period variation for WASP-103b. However, the data show a hint of an orbital period increase instead of a decrease, as is expected for tidal decay. This could be either due to a visual companion star if this star is bound, the Applegate effect, or a statistical artefact. Conclusions: The estimated Love number of WASP-103b is similar to Jupiter's. This will allow us to constrain the internal structure and composition of WASP-103b, which could provide clues on the inflation of hot Jupiters. Future observations with James Webb Space Telescope can better constrain the radial Love number of WASP-103b due to their high signal-to-noise and the smaller signature of limb darkening in the infrared. A longer time baseline is needed to constrain the tidal decay in this system. The transit light curves are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/657/A52
The origin of nitrogen in Earth's mantle: constraints from basalts 15 N/ 14 N and N2/ 3 He ratios
No full textInternational audiencePlate tectonics is thought to be a major driver of volatile redistribution on Earth. The budget of nitrogen in Earth's mantle has been suggested to be almost entirely surfacederived. Recycling would contribute nitrogen with relatively heavy 15 N/ 14 N isotope ratios to Earth's mantle. This could explain why the Earth's mantle 15 N/ 14 N isotope ratio is substantially higher than both solar gases and chondritic parent bodies akin to enstatite chondrites. Here, published nitrogen isotope data of mid-ocean ridge and ocean island basalts are compiled and used to evaluate the nitrogen subduction hypothesis. Nitrogen isotope ratios are used in conjunction with published N2/ 3 He and K2O/TiO2 ratios on the same basalts. Assuming that 3 He is not recycled, N2/ 3 He ratios are argued to trace nitrogen addition to mantle sources via subduction. Various mantle source enrichments for basalts are tracked with K2O/TiO2 ratios: elevated K2O/TiO2 ratios are assumed to primarily reflect the contributions of recycled components in the basalts mantle sources. The main result of our data compilation is that for most basalts, d 15 N and N2/ 3 He remain constant across a vast range of K2O/TiO2 ratios. Mid-ocean ridge basalts have d 15 N signatures that are lower than air by ~ 4‰ and an average N2/ 3 He ratio of 3.7 (±1.2) x10 6 (95% confidence, n= 30). Published d 15 N and N2/ 3 He are invariant across K2O/TiO2 ratios that vary over a factor of ~ 20. Using estimates of slab K2O/TiO2 and [TiO2], the observed invariant d 15 N and N2/ 3 He ma
Near-zero 33 S and 36 S anomalies in Pitcairn basalts suggest Proterozoic sediments in the EM-1 mantle plume
No full textInternational audienceVolcanic rocks erupted among Pitcairn seamounts sample a mantle plume that exhibits an extreme Enriched Mantle-1 signature. The origin of this peculiar mantle endmember remains contentious, and could involve the recycling of marine sediments of Archean or Proterozoic ages, delaminated units from the lower continental crust, or metasomatized peridotites from a lithospheric mantle. Here, we report the sulfur multi-isotopic signature (32 S, 33 S, 34 S, 36 S) of 15 fresh submarine basaltic glasses from three Pitcairn seamounts. We observe evidence for magmatic degassing of sulfur from melts erupted ~2,000 meters below seawater level (mbsl). Sulfur concentrations are correlated with eruption depth, and range between 1300 ppm S (collected ~ 2,500 mbsl) and 600 ppm S (~2,000 mbsl). The d 34 S values can be accounted for under equilibrium isotope fractionation during degassing, with agas-melt between 1.0020 and 1.0001 and starting d 34 S values between-0.9‰ and +0.6‰. The d 34 S estimates are similar or higher than MORB signatures, suggesting the contribution of recycled sulfur with a ~ 1‰ 34 S enrichment compared to pacific upper mantle. The D 33 S and D 36 S signatures average at +0.024±0.007‰ and +0.02±0.07‰ vs. CDT, respectively (all 1s). Only D 33 S is statistically different from MORBs, by +0.02‰. The D 33 S enrichment is invariant across degassing and sulfide segregation. We suggest it reflects a mantle source enrichment rather than a high-temperature fractionation of S in the basalts. Despite the small magnitude of the 33 S-36 S variations, our data require a substantial amount of recycled sulfur overwhelm the Pitcairn mantle source. We show that models involving metasomatized peridotites, lower crust units, or Archean sediments, may be viable, but are restricted to narrow sets of circumstances. Instead, scenarios involving the contribution of Proterozoic marine sediments appear to be the most parsimonious explanation for the EM-1 signature at Pitcairn
The mosquito microbiome includes habitat-specific but rare symbionts
No full textInternational audienceMicrobial communities are known to influence mosquito lifestyles by modifying essential metabolic and behavioral processes that affect reproduction, development, immunity, digestion, egg survival, and the ability to transmit pathogens. Many studies have used 16S rRNA gene amplicons to characterize mosquito microbiota and investigate factors that influence host-microbiota dynamics. However, a relatively low taxonomic resolution due to clustering methods based on arbitrary threshold and the overall dominance of Wolbachia or Asaia symbionts obscured the investigation of rare members of mosquito microbiota in previous studies. Here, we used high resolution Shannon entropy-based oligotyping approach to analyze the microbiota of Culex pipiens, Culex quinquefasciatus and Aedes individuals from continental Southern France and overseas Guadeloupe as well as from laboratories with or without antibiotics treatment. Our experimental design that resulted in a series of mosquito samples with a gradient of Wolbachia density and relative abundance along with high-resolution analyses of amplicon sequences enabled the recovery of a robust signal from typically less accessible bacterial taxa. Our data confirm species-specific mosquito-bacteria associations with geography as a primary factor that influences bacterial community structure. But interestingly, they also reveal co-occurring symbiotic bacterial variants within single individuals for both Elizabethkingia and Erwinia genera, distinct and specific Asaia and Chryseobacterium in continental and overseas territories, and a putative rare Wolbachia variant. Overall, our study reveals the presence of previously overlooked microdiversity and multiple closely related symbiotic strains within mosquito individuals with a remarkable habitat-specificity
Use of different cotton pest control strategies (conventional, organic and transgenic) had no impact on insecticide resistance in Anopheles gambiae s.l. populations in Burkina Faso, West Africa
No full textInternational audienceResistance to insecticides in the mosquito Anopheles gambiae s.l can jeopardize malaria vector control strategies. Previous studies have shown that the agricultural chemicals, used particularly for cotton protection, selected the insecticide resistant malaria vectors. Our study aimed at assessing the impact of three cotton pest management strategies in different ecological settings (conventional, organic and transgenic cotton growing areas) on the i) susceptibility to insecticides belonging to pyrethroids, DDT, carbamate and organophosphate tested on the main malaria vectors and ii) frequencies of kdr L1014F, during rainy season of 2008, 2009, 2013 and 2014 in Burkina Faso. From 2008 to 2014, most of populations of An. gambiae s.l from the three cotton growing areas exhibited a reduction in susceptibility to almost all insecticide classes. The frequency of kdr L1014F mutations varied depending on both localities and species within the An. gambiae complex, but no relationship was found between the cotton pest control strategies and the frequency of kdr L1014F. These results confirm the worrying status of insecticide multi-resistance within the vector mosquito species from Burkina Fas
Dynamic contributions of stratified groundwater to streams controls seasonal variations of streamwater transit times
No full textInternational audienceStreamwater transit time distributions display a variable proportion of old waters ( ≥1 yr). We hypothesize that the corresponding long transit times result from groundwater contributions to the stream and that seasonal streamwater transit time variations result from 1) the variable contributions of different flowpaths (overland flow, seepage flow and baseflow) and 2) the stratification of groundwater residence times. We develop a parsimonious model to capture the groundwater contribution to the stream discharge and its effect on transient transit times. Infiltration is partitioned according to the aquifer saturation between Boussinesq groundwater flow and overland flow. Time-variable transit time distributions are obtained with a new 2D particle tracking algorithm. Hydraulic conductivity, total and drainable porosities are calibrated by using discharge and CFC tracer data on a crystalline catchment located in Brittany (France). The calibrated models succeed in reproducing CFCs concentrations and discharge dynamics. The groundwater flow contribution to the stream is controlled by the aquifer hydraulic conductivity, while its age is controlled by the drainable and total porosities. Old groundwater ( ≥1 yr) is the source for approximately 75 % of the streamflow with strong seasonal variations (between 40 and 95 %). Mean transit times are approximately 13 years, varying between 6 and 20 years, inversely proportional to the groundwater contribution. These seasonal variations are driven by the groundwater versus overland flow partitioning. The stratification of groundwater residence times in the aquifer plays a minor role in the streamwater transit times but is key for the transit time dynamics of the groundwater contribution to the stream
Clinique de l'activité et anthropologie culturaliste : étude de cas en formation continue dans le secteur de la sécurité privée. Augmenter la satisfaction dans sa pratique professionnelle pour mieux vivre son métier
No full textThe professional problem that animated this study concerns the lack of coherence between the training prescriptions and the realities on the ground experienced by the private security agents at the CHU from BELLEPIERRE. The object of study chosen, relating to the continuing training of security guards, was studied within the framework of a technological research programme based on clinical approaches to activity and culturalist anthropology. The ancillary assumptions selected posit in essence that the transmission of professional experience between experienced and novice peers within the framework of a continuing training system is likely to promote the learning of new systems of rules and the professional development of each of the parties on the basis of the interpreted follow-up of these. The data collection method made it possible to produce a system based on the rules learned and/or followed by the security guards to draw up in an ostensive and ostensible way the meaning of the rules of trade and to promote the power of action of the security agents in situations of reception of the public in the emergency rooms of the CHU. The results show that the learning of new rules by expert and novice security guards allowed them to solve professional difficulties, it also contributed to the professional development of the peer trainer and the trained peer and promoted increased satisfaction. This opens up prospects for the continuous training of security guards anchored on the real activity of employees, the different styles and rules of trades adopted by the community of practice as well as their follow-up over time.Le problème professionnel qui a animé cette étude porte sur le manque de cohérence entre les prescriptions de formation et les réalités de terrain vécues par les agents de sécurité privée au CHU de BELLEPIERRE (Saint Denis de La Réunion). L’objet d’étude retenu, relatif à la formation continue des agents de sécurité a été étudié dans le cadre d’un programme de recherche technologique fondé sur les approches clinique de l’activité et l’anthropologie culturaliste. Les hypothèses auxiliaires retenues posent en substance que la transmission d’expériences professionnelles entre pairs expérimentés et novices dans le cadre d’un dispositif de formation continue est susceptible de favoriser l’apprentissage de nouveaux systèmes de règles et le développement professionnel de chacune des parties à partir du suivi interprété de celles-ci. La méthode de recueil des données a permis de produire un dispositif fondé sur les règles apprises et/ou suivies par les agents de sécurité permettant de dresser de manière ostensive et ostensible la signification des règles de métier et de favoriser le pouvoir d’action des agents de sécurité en situation d’accueil du public aux urgences du CHU. Les résultats montrent que l’apprentissage de nouvelles règles par les agents de sécurité experts et novices leurs a permis de résoudre des difficultés professionnelles. Cela a aussi contribué au développement professionnel du pair formateur et du pair formé en favorisant l’augmentation de leur satisfaction. Ceci ouvre des perspectives en formation continue des agents de sécurité ancrées sur l’activité réelle des salariés, des différents styles et des règles de métiers adoptées par la communauté de pratique ainsi que leurs suivis dans le temps
A bed pressure correction of the friction term for depth-averaged granular flow models
No full textInternational audienceDepth-averaged models, such as the Savage-Hutter model with Coulomb or Pouliquen friction laws, do not in some cases preserve the physical threshold of motion. In particular, the simulated granular mass can start to flow (or stay at rest) even if the slope angle of its free surface is lower (or higher) than the repose angle of the granular material involved. The problem is related to the hydrostatic pressure assumption, associated with the direction of integration, which is orthogonal to a reference plane or a reference bottom. We propose here an initial method to correct this misleading behavior. Firstly, we define a correction of the friction term that accounts for the Jacobian of a change of coordinates, making it possible to reproduce the physical threshold of motion and thus the solutions at rest. Secondly, we observe that the 3D model presented in [F. Bouchut, I. Ionescu, and A. Mangeney. An analytic approach for the evolution of the staticflowing interface in viscoplastic granular flows. Commun, Math. Sci., 14(8):2101-2126, 2016] verifies the physical thresholds of motion because it is based on a second order correction of the pressure valid for slow granular flows. The correction proposed here ensures that the model preserves, up to the second order, the physical threshold of motion defined by the repose angle of the material. Several numerical tests are presented to illustrate certain problems related to classical depth averaged models and the remedial effect of the proposed correction, in particular through comparisons with experimental data. We finally show that this correction is not exact far from the starting and stopping phases of the granular avalanche and should be improved by adding other second order terms in the pressure approximation
Linking Drone and Ground-Based Liana Measurements in a Congolese Forest
No full textInternational audienceLianas are abundant and diverse in tropical forests and impact forest dynamics. They occupy part of the canopy, forming a layer of leaves overtopping tree crowns. Yet, their interaction with trees has been mainly studied from the ground. With the emergence of drone-based sensing, very high-resolution data may be obtained on liana distribution above canopies. Here, we assessed the relationship between common liana ground measurements and drone-determined liana leaf coverage over tree crowns, tested if this relationship is mediated by liana functional composition, and compared the signature of liana patches and tree crowns in our drone images. Using drone platforms, we acquired very high resolution RGB and multispectral images and LiDAR data over two 9-ha permanent plots located in northern Republic of Congo and delineated liana leaf coverage and individual tree crowns from these data. During a concomitant ground survey, we focused on 275 trees infested or not by lianas, for which we measured all lianas ≥ 1 cm in diameter climbing on them (n = 615) and estimated their crown occupancy index (COI). We additionally measured or recorded the wood density and climbing mechanisms of most liana taxa. Contrary to recent findings, we found significant relationships between most ground-derived metrics and the top-of-view liana leaf coverage over tree crowns. Tree crown infestation by lianas was primarily explained by the load of liana climbing on them, and negatively impacted by tree height. Liana leaf coverage over individual tree crowns was best predicted by liana basal area and negatively mediated by liana wood density, with a higher leaf area to diameter ratio for light-wooded lianas. COI scores were concordant with drone assessments, but two thirds differed from those obtained from drone measurements. Finally, liana patches had a higher light reflectance and variance of spectral responses than tree crowns in all studied spectra. However, the large overlap between them challenges the autodetection of liana patches in canopies. Overall, we illustrate that the joint use of ground and drone-based data deepen our understanding of liana-infestation pathways and of their functional and spectral diversity. We expect drone data to soon transform the field of liana ecology
Gestion des finances publiques locales pour le développement des ETD : Cas du Secteur des Walendu Pitsi
No full textInternational audienceThis article, written under the theme: Managing local public finances for the development of ETDs with experience in the Walendu Pitsi sector," is rare in proposing to explain the purpose for which ETDs are developing a budget and understand how this local financial law is enforced. Following the results obtained and analyzed after the operation of the documents of the Budgets of this entity, which enjoys financial autonomy over the space of three years (2013-2015), revenue forecasts and expenditure execution reveal that expected revenues were weakly mobilized: in the order of 20.02% in 2013, 5.00% in 2014 and 34.84% in 2015 and executed similarly according to the proportion of 19.93% in 2013, 7.13% in 2014 and 32.92% in 2015. This modest revenue and expenditure performance has a direct negative impact on governance and peacekeeping (strengthening institutions), macroeconomic stability and growth and improvement access to social services, reducing vulnerability and supporting community dynamics in the Walendu-Pitsi sector.The public authority in high court must therefore go beyond believing strictly in the financial autonomy of the ETDs otherwise it must be relative, and must be appreciated in terms of the desire to control the decentralizing process in a certain way, because ETD are seen more as conveyor belts of its own policies than as centres of autonomous decisions.Le présent article rédigé sous le thème : Gestion des finances publiques locales pour le développement des ETD (Entité Territoriale Décentralisée) avec l’expérience dans le secteur des Walendu Pitsi " est rare qui se propose d'expliquer la finalité pour laquelle les ETD s'élaborent un budget et de comprendre le mode d'exécution de cette loi financière locale. Au terme des résultats obtenus et analysés après l’exploitation des documents des Budgets de cette entité jouissant de l’autonomie financière sur l’espace de trois années (2013 – 2015), des prévisions en recettes et l’exécution des dépenses nous révèlent que les recettes prévues ont été faiblement mobilisées soit de l’ordre de 20,02% en 2013, 5,00% en 2014 et 34,84% en 2015 et exécutées de même suivant la proportion de 19,93% en 2013, 7,13% en 2014 et 32,92% en 2015.Cette modicité de la réalisation des recettes et d’exécution des dépenses a des répercussions négatives directes sur la gouvernance et le maintien de la paix (renforcement des institutions), la stabilité macroéconomique et la croissance et l'amélioration d'accès aux services sociaux, la réduction de la vulnérabilité, appui à la dynamique communautaire en secteur des Walendu – Pitsi.Le pouvoir public en haute instance doit donc se dépasser de croire strictement à l'autonomie financière des ETD sinon, celle-ci doit être relative, et doit s'apprécier au regard de la volonté de contrôler le processus décentralisateur d'une certaine façon, car les ETD sont plus considérés comme des courroies de transmission de ses propres politiques que comme des centres des décisions autonomes