Journal of Next-Generation Research 5.0
Not a member yet
7559 research outputs found
Sort by
Modeling the emergence of migratory corridors and foraging hot spots of the green sea turtle
No full textInternational audienceEnvironmental factors shape the spatial distribution and dynamics of populations. Understanding how these factors interact with movement behavior is critical for efficient conservation, in particular for migratory species. Adult female green sea turtles, Chelonia mydas, migrate between foraging and nesting sites that are generally separated by thousands of kilometers. As an emblematic endangered species, green turtles have been intensively studied, with a focus on nesting, migration, and foraging.Nevertheless, few attempts integrated these behaviors and their trade‐offs by considering the spatial configurations of foraging and nesting grounds as well as environmental heterogeneity like oceanic currents and food distribution. We developed an individual‐based model to investigate the impact of local environmental conditions on emerging migratory corridors and reproductive output and to thereby identify conservation priority sites. The model integrates movement, nesting, and foraging behavior. Despite being largely conceptual, the model captured realistic movement patterns which confirm field studies. The spatial distribution of migratory corridors and foraging hot spots was mostly constrained by features of the regional landscape, such as nesting site locations, distribution of feeding patches, and oceanic currents. These constraints also explained the mixing patterns in regional forager communities. By implementing alternative decision strategies of the turtles, we found that foraging site fidelity and nesting investment, two characteristics of green turtles' biology, are favorable strategies under unpredictable environmental conditions affecting their habitats. Based on our results, we propose specific guidelines for the regional conservation of green turtles as well as future research suggestions advancing spatial ecology of sea turtles. Being implemented in an easy to learn open‐source software, our model can coevolve with the collection and analysis of new data on energy budget and movement into a generic tool for sea turtle research and conservation. Our modeling approach could also be useful for supporting the conservation of other migratory marine animals
Storm-induced precipitation variability control of long-term erosion
No full textInternational audienceErosion is often treated as a continuous process, yet it occurs through discrete events such as floods and landslides of variable magnitude and periodicity. It has also long been expected to be strongly dependent on precipitation, however, the influence of temporal rainfall variability upon long-term evolution of landscapes remains unclear. Here we report high erosion rates (0.8 to ∼10 mmyr−1over ∼70 ka) estimated from paleovolcanic reconstructions across a steep rainfall gradient on Reunion Island, which show that long-term erosion rates are influenced by the cyclone-induced variability of precipitation. Geostatistical analysis of 30 years of daily rainfall records reveals that erosion rates are high where the local climate is the driest and where the difference in intensity between extreme rainfall events and prevailing precipitation is the strongest. This implies that the intrinsic variability of precipitation impacts landscape evolution not only through extreme meteorological events, but also through background rainfall-induced parameters such as humidity and dryness, which modulate the erosion threshold of the Earth’s Critical Zone
Ground-based Assessment of the First Year of Sentinel-5p Tropospheric Ozone Data
No full textInternational audienceTropospheric ozone is a pollutant that damages ecosystems and triggers human health problems. Ozone concentrations are highly variable over time and across the troposphere, which poses clear challenges to deepen our understanding of the processes involved in the production and transport of ozone. Further progress depends on the availability of instruments capable of measuring tropospheric ozone and its distribution at finer spatio-temporal scales. The TROPOMI instrument on the Sentinel-5p platform, launched into an early afternoon polar orbit in October 2017, combines a high spatial resolution, a large swath width and the spectral measurement characteristics required to deliver tropospheric ozone data records at unprecedented detail. The first of these products was released during Fall 2018. It consists in 0.5° (latitude) by 1° (longitude) resolved daily maps of 3-day moving mean values of the tropospheric ozone column between 20°S and 20°N, and it is computed using the convective-cloud method (CCD). A second data product consists in maps of tropical upper tropospheric ozone mixing ratio at a coarser spatial and temporal resolution. It is based on a cloud slicing algorithm (CSA), which is currently being fine-tuned for release in the very near future. A third data product, also under development at the time of this abstract, consists of the vertical profile of ozone concentration in the global troposphere and stratosphere, retrieved with the classical Optimal Estimation (OE) technique. We present here an assessment of the quality of the first year of the different tropospheric ozone column data sets retrieved from Sentinel-5p TROPOMI measurements, carried out within the context of ESA’s Sentinel-5p Mission Performance Center (MPC) and the S5PVT AO project CHEOPS-5p (Validation of Copernicus Height-resolved Ozone data Products from Sentinel-5p TROPOMI using global sonde and lidar networks, #28587). The first stage of this analysis consists of an inspection of the tropospheric ozone fields for structures which are potentially introduced in the measurement process. Sampling effects, in particular, are a possible source of uncertainty as the CCD product is derived from binned TROPOMI total ozone column data. Another structure introduced by retrieval assumptions would be the dependence of the quality of Sentinel-5p retrieved total column data to cloud parameters. In a second stage the satellite data are confronted to quality-assured ozonesonde and –tentatively– ground-based lidar measurements from the NDACC, SHADOZ and TOLNET networks. These well-characterized observational data records serve as a reference to evaluate the bias and uncertainty of the Sentinel-5p data, and their dependence on influence quantities. The study concludes with an assessment of the compliance of Sentinel-5p tropospheric ozone data with respect to mission and user requirements for key data applications
Numerical simulation of surface solar radiation over Southern Africa. Part 2: projections of regional and global climate models.
No full text31 pagesInternational audienceIn the second part of this study, possible impacts of climate change on Surface Solar Radiation (SSR) in Southern Africa (SA) are evaluated. We use outputs from 20 regional climate simulations from five Regional Climate Models (RCM) that participate in the Coordinated Regional Downscaling Experiment program over the African domain (CORDEX-Africa) along with their 10 driving Global Climate Models (GCM) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Multi-model mean projections of SSR trends are consistent between the GCMs and their nested RCMs. However, this consistency is not found for each GCM/RCM setup. Over the centre of SA, GCMs and RCMs project a statistically significant increase in SSR by 2099 of about + 1 W/m2 per decade in RCP4.5 (+ 1.5 W/m2 per decade in RCP8.5) during the DJF season in their multi-model means. Over Eastern Equatorial Africa (EA-E) a statistically significant decrease in SSR of about − 1.5 W/m2 per decade in RCP4.5 (− 2 W/m2 per decade in RCP8.5) is found in the ensemble means in DJF, whereas in JJA SSR is predicted to increase by about + 0.5 W/m2 per decade under RCP4.5 (+ 1 W/m2 per decade in RCP8.5). SSR projections are fairly similar between RCP8.5 and RCP4.5 before 2050 and then the differences between those two scenarios increase up to about 1 W/m2 per decade with larger changes in RCP8.5 than in RCP4.5 scenario. These SSR evolutions are generally consistent with projected changes in Cloud Cover Fraction over SA and may also related to the changes in atmosphere water vapor content. SSR change signals emerge earlier out of internal variability estimated from reanalyses (European Centre for Medium-Range Weather Forecasts Reanalysis ERA-Interim, ERAIN) in DJF in RCMs than in GCMs, which suggests a higher sensitivity of RCMs to the forcing RCP scenarios than their driving GCMs in simulating SSR changes. Uncertainty in SSR change projections over SA is dominated by the internal climate variability before 2050, and after that model and scenario uncertainties become as important as internal variability until the end of the 21st century
Timing of the Brunhes-Matuyama transition constrained by U-series disequilibrium
No full textInternational audienceU-series disequilibrium measurements carried out on thermogenic travertine samples from a 12.6 m-long core and a 10 m-thick section from southeastern Morocco yielded finite ages ranging from 500 ka to the present-day, as well as two clusters determined to be older than 500 ka. The calculation of initial 234 U/ 238 U activity ratios in all samples younger than 500 ka shows high, reasonably constant values, with an average of 5.172 ± 0.520 (one standard deviation). Assuming that this value prevailed for periods older than 500 ka, we derived ages of up to approximately 1.2 Ma using the initial 234 U excess decay. Our results indicate that the two older clusters have ages of 776 ± 14 ka for samples from between 8 and 10.1 m and 1173 ± 22 ka for deeper samples respectively. The palaeomagnetic record of the core shows normal polarity inclinations from the surface to around 9 m followed by reverse polarity inclination and antipodal declinations. The inversion is attributed to the Brunhes-Matuyama transition. 234 U excess ages for the interval corresponding to the part of the core where the polarity inversion occurred are in the range of 735 ± 51 to 794 ± 54 ka, with an arithmetic mean value of 776 ± 14 ka for the B-M transition. This age is in good agreement with that determined previously using other dating methods
Prototype d'une antenne patch à cavité en croix à polarisation croisée pour la récupération d'énergie dans la bande ISM à 2,45 GHz
No full textInternational audienceCe résumé présente la réalisation d'un prototype d'antenne patch à cavité en croix à polarisation croisée pour des applications de récupération d'énergie RF. L'antenne est composée d'un motif carré dont une cavité est creusée au centre en forme de croix comprenant ainsi la couche de cuivre et le substrat. La forme de croix ainsi que l'unique ligne d'alimentation positionnée dans un angle du motif permettent d'obtenir la polarisation croisée à la fréquence de 2,45 GHz. Deux substrats sont utilisés : le Rogers 5880, pour des mesures en standalone et le FR4 pour comparer les performances de l'antenne en croix associée à un redresseur RF/DC avec une antenne patch rectangulaire standard. Les résultats montrent un gain à 48,7% en plus sur la tension redressée par l'antenne à cavité en croix à une charge de 6 kΩ
Le préverbe i en créole réunionnais : étude de syntaxe comparée
No full textThis thesis is part of the field of classical linguistics. It deals with the study of the syntactic functioning of the preverb i in Reunion creole. A precise inventory of its uses from a descriptive point of view is made in order to determine its conditions of appearance and the conditions in which it does not appear. Two major categories of hypotheses are confronted: seamantic-based hypotheses and purely syntactical hypotheses. This is to demonstrate the merits of the second approach and the weak points of the first. Already published theories on the problem of i are examined. To better understand the value of Reunionese i, a comparaison of the structures of French-based creole languages is carried out: Reunion creole which is at the forefront of our reseach; Mauritian and Seychellois Creoles in Indian ocean region and Martinican, Guadeloupe and Haitian creoles of the Atlantic ocean regionCette thèse s'inscrit dans le champ de la linguistique classique. Elle aborde l'étude du fonctionnement syntaxique du préverbe i en créole réunionnais. Un inventaire précis de ses emplois d'un point de vue descriptif est fait afin de déterminer ses conditions d'apparition et les conditions où il n'apparaît pas. Deux grandes catégories d'hypothèses sont confrontées : les hypothèses à base sémantique et les hypothèses à base purement syntaxique. Il s'agit de démontrer le bien-fondé de la seconde approche et les point faibles de la première. Les théories déjà publiées sur le problème du i sont examinées. Pour mieux saisir la valeur du i réunionnais, une comparaison des structures des créoles à base lexicale française est réalisée : le créole réunionnais qui est au premier plan de notre recherche ; les créoles mauricien et seychellois de la région de l'océan Indien et les créoles martiniquais, guadeloupéen et haïtien de la région de l'océan Atlantique
The Effect of Agulhas Eddies on Absorption and Transport of Anthropogenic Carbon in the South Atlantic Ocean
No full textInternational audienceThe South Atlantic Ocean is currently undergoing significant alterations due to climate change. This region is important to the global carbon cycle, but marine carbon data are scarce in this basin. Additionally, this region is influenced by Agulhas eddies. However, their effects on ocean biogeochemistry are not yet fully understood. Thus, we aimed to model the carbonate parameters in this region and investigate the anthropogenic carbon (Cant) content in 13 eddies shed by the Agulhas retroflection. We used in situ data from the CLIVAR/WOCE/A10 section to elaborate total dissolved inorganic carbon (CT) and total alkalinity (AT) models and reconstruct those parameters using in situ data from two other Brazilian initiatives. Furthermore, we applied the Tracer combining Oxygen, inorganic Carbon, and total Alkalinity (TrOCA) method to calculate the Cant, focusing on the 13 identified Agulhas eddies. The CT and AT models presented root mean square errors less than 1.66 and 2.19 μmol kg−1, indicating Global Ocean Acidification Observing Network climate precision. The Cant content in the Agulhas eddies was 23% higher than that at the same depths of the surrounding waters. We observed that Agulhas eddies can play a role in the faster acidification of the South Atlantic Central Water
Faut-il tout dire à son patient ? La communication en situation palliative : point de vue des médecins généralistes
No full textDoes everything have to be said to the patient ? Patient-physician communication in palliative situation : physicians’ views.Introduction : Nowadays, information is an unquestionable right to the patient. However, in a palliative situation, patient vulnerability and the impact of some informations has to be regarded. What is appropriate information to the patient ? Does everything has to be said, every time ? Our study aims to consider the physicians’ views about communication with the patient in a palliative situation.Method: We conducted qualitative research with semi-structured interviews with general practitioners in La Réunion.Results: 12 interviews had been conducted between September 2018 to January 2019. Physicians suggested that information to the patient should not have to be detailed, every time. Physicians advised to adjust and provide informations progressively. They explained the need to adapt themselves to the singularity of each situation continually. The physician availability and their presence were described as the main posture to preserve. Discussion: If information to a patient is recommanded, everything does not have to be said, all the time. The patient's request of honesty from a physician outweighs the need for complete and scientific information. There is a broad request for a relationship based on trust and respect between the patient and the physician. The physician has to create a « space of truth » with each patient to find the right balance between honest information and the respect of patients’ hope, the right balance between autonomy and beneficience.Faut-il tout dire à son patient ? La communication médecin-patient en situation palliative : point de vue des médecins généralistes.Introduction : L’information au patient est aujourd’hui un droit incontestable. Cependant, en situation palliative, la vulnérabilité du patient et le poids de certaines informations questionnent. Est-ce que tout doit être dit, tout le temps ? Qu'est-ce qu'une information appropriée ? L’objectif de notre étude était de recueillir le point de vue des médecins généralistes sur les échanges d’informations médicales avec leurs patients en situation palliative. Méthode : Une étude qualitative à visée compréhensive a été réalisée par entretiens semi-directifs auprès de médecins généralistes à la Réunion. Résultats : 12 entretiens ont été réalisés de septembre 2018 à janvier 2019. Les médecins suggéraient que l’information ne devait pas être exhaustive. Ils conseillaient de nuancer, de distiller l’information. Ils rappelaient la singularité de chaque situation demandant au médecin de s’adapter en permanence. Ils insistaient sur l’importance de la disponibilité du médecin ainsi que sur son rôle d’accompagnant. Discussion : Même si l’information au patient est souhaitable, cela ne constitue pas une obligation d’exhaustivité et d’immédiateté. La demande de vérité va au-delà du « dire » ou du « non-dire ». Elle correspond davantage à la création d’une relation authentique, plutôt qu’à la délivrance d’une information scientifique rigoureuse. Le médecin doit accompagner son patient, pas à pas, dans un « espace de vérité » afin de trouver le juste équilibre entre une information loyale et le respect de l’espoir du patient, entre autonomie et bienfaisance
Towards a multi-agent model to prevent damage caused by cocoa mirids to cocoa pods
No full textCo-localisées avec la Plate-Forme Intelligence Artificielle (PFIA 2019)International audienceAgriculture in general and cocoa farm in particular is one of the primary sources of income for several African countries. Although quite useful for the development of Africa, cocoa production is faced with several challenges like the diseases of cocoa trees. Mirid (Sahlbergella singularis) is the worst pest affecting cocoa production across west Africa causing 30% to 40% of damage on cocoa production. It is difficult to control the mirids’ population and its impact on the cacao production. Related works on mirids studied the mirids population as a macroscopic entity without considering local interactions of individual mirids. These models did not consider the behaviours and the environment of mirids which are essential due to their complexity. To overcome these drawbacks, this paper proposes an agent-based model of mirids considering the individual interactions of mirids within the environment. The proposed model consists of agents representing the mirids through their life cycle in cocoa farm environments. It is based on the biological and ecological partial knowledge found in the literature, and is built according to the GAIA methodology. The main assets of this model are the reproduction of the dynamics of the mirids on a cocoa pod and damage caused by them at the micro level for human users (entomologists, agricultural engineers, farmers and decision makers) to thoroughly understand the phenomena and the emergent properties outcomes.L’agriculture en général et la culture du cacao en particulier est l’une des principales sources de revenus de plusieurs pays africains. Cependant, la production du cacao est confrontée à plusieurs défis tels que les maladies et l’attaque des insectes nuisibles. Les mirides (Sahlbergella singularis) sont les insectes les plus préjudiciables à la culture du cacao en Afrique. Avec 30 à 40 % de dommages sur la production, il est difficile de contrôler la population des mirides ainsi que son impact sur la production de cacao. Les travaux précédents sur les mirides, étudient la population de cet insecte selon le point de vue macroscopique sans tenir compte des interactions locales entre les mirides. Ces modèles ne prennent pas en compte les comportements individuels des mirides et leurs interactions avec l’environnement qui sont essentiels en raison de leurs complexités. Pour remédier à ces insuffisances, le présent article propose un modèle de mirides à base d’agents prenant en compte les interactions individuelles des mirides dans leur environnement. Le modéle proposé est constitué d’agents représentant le cycle de vie du miride sur une cabosse de cacao. Il est basé sur les connaissances biologiques et écologiques du miride, et est construit selon la méthodologie GAIA. Ces modèles ainsi que leurs implémentations sont destinés à des utilisateurs tels que les entomologistes, les ingénieurs agronomes, les agriculteurs et les décideurs. Cela leur permettra de mieux comprendre les phénomènes émergents dues aux mirides ainsi que leurs propriétés