Journal of Next-Generation Research 5.0
Not a member yet
7559 research outputs found
Sort by
Scaling laws of convection for cooling planets in a stagnant lid regime
No full textInternational audienc
Traveling wave solutions for monotone systems of impulsive reaction-diffusion equations
No full textInternational audienceMany systems in life sciences have been modeled by Reaction Diffusion Equations (RDE). However, under some circumstances, these biological systems may experience instantaneous and periodic perturbations (e.g. harvest, birth, release) such that an appropriate formalism is necessary, using, for instance, Impulsive Reaction Diffusion Equations (IRDE). While the study of traveling waves for monotone RDE has been done in several works, like [2], very little has been done in the case of (monotone) IRDE. Based on recursion equations theory [1], we aim to present in this talk a generic framework that handles two main issues of IRDE. First, it allows the characterization of spreading speeds in monotone systems of IRDE. Second, it deals with the existence of traveling waves for (nonlinear) monotone systems of IRDE. We apply our methodology to a system of IRDE that models tree-grass interactions in fire-prone savanna [4], extending the result obtained in [3]
Thermally induced icequakes detected on blue ice areas of the East Antarctic ice sheet
No full textInternational audienceOver a year of seismic observations, ∼5000 short duration icequakes were detected by a permanent broadband station installed at the Princess Elisabeth base, located ∼180 km inland in eastern Dronning Maud Land, East-Antarctica. Icequake detection via seismic waveform pattern recognition indicates the presence of two dominating clusters of events, totalizing ∼1500 icequakes. The corresponding icequake locations point towards two distinct zones of outcropping blue ice areas (BIAs) located respectively at 4 and 1 km from the seismic station, both on the leeward side of a nunatak protruding through the ice sheet. The temporal occurrence of these icequakes suggests a close genetic link with thermal contraction of ice caused by significant surface cooling controlled, in summer by variations in diurnal solar radiation and in winter by strong cooling during cold katabatic regimes. Further analysis demonstrates the dependence of these icequakes on the absolute surface temperature and on its temporal change. Besides providing information on the ice fracture mechanics and rheology, investigations of thermal icequakes may be regarded as a ground-based proxy for the monitoring of the thermal state of BIAs, and characterization of ice-sheet ablation zones
Tomography of crust and lithosphere in the western Indian Ocean from noise cross-correlations of land and ocean bottom seismometers
No full textInternational audienceWe use seismic noise cross-correlations to obtain a 3-D tomography model of S V-wave velocities beneath the western Indian Ocean, in the depth range of the oceanic crust and uppermost mantle. The study area covers 2000 × 2000 km 2 between Madagascar and the three spreading ridges of the Indian Ocean, centred on the volcanic hotspot of La Réunion. We use seismo-grams from 38 ocean bottom seismometers (OBSs) deployed by the RHUM-RUM project and 10 island stations on La Réunion, Madagascar, Mauritius, Rodrigues, and Tromelin. Phase cross-correlations are calculated for 1119 OBS-to-OBS, land-to-OBS, and land-to-land station pairs, and a phase-weighted stacking algorithm yields robust group velocity measurements in the period range of 3-50 s. We demonstrate that OBS correlations across large interstation distances of >2000 km are of sufficiently high quality for large-scale tomography of ocean basins. Many OBSs yielded similarly good group velocity measurements as land stations. Besides Rayleigh waves, the noise correlations contain a low-velocity wave type propagating at 0.8-1.5 km s −1 over distances exceeding 1000 km, presumably Scholte waves travelling through seafloor sediments. The 100 highest-quality group velocity curves are selected for tomographic inversion at crustal and lithospheric depths. The inversion is executed jointly with a data set of longer-period, Rayleigh-wave phase and group velocity measurements from earthquakes, which had previously yielded a 3-D model of Indian Ocean lithosphere and asthenosphere. Robust resolution tests and plausible structural findings in the upper 30 km validate the use of noise-derived OBS correlations for adding crustal structure to earthquake-derived tomography of the oceanic mantle. Relative to crustal reference model CRUST1.0, our new shear-velocity model tends to enhance both slow and fast anomalies. It reveals slow anomalies at 20 km depth beneath La Réunion, Mauritius, Rodrigues Ridge, Madagascar Rise, and beneath the Central Indian spreading ridge. These structures can clearly be associated with increased crustal thickness and/or volcanic activity. Locally thickened crust beneath La Réunion and Mauritius is probably related to magmatic underplating by the hotspot. In addition, these islands are characterized by a thickened lithosphere that may reflect the depleted, dehydrated mantle regions from which the crustal melts where sourced. Our tomography model is available as electronic supplement
Sensitivity analysis and optimization of a compressed air energy storage (CAES) system powered by a photovoltaic plant to supply a building
No full textInternational audienceOne of the handicaps of the large-scale integration of solar energy is due to its variability and its intermittency. The main way to overcome this issue is the energy storage technology. Knowing the high cost of batteries and their impact on the environment, we simulate a storage system based on compressed air and acting as a battery system. The CAES consists in storing the air at a high pressure in a tank during the period when the energy source is abundant, i.e., cheap, or when the energy demand is low. The compressed air is later expanded through an air turbine which generates electricity during the high demand periods, i.e. when the energy source becomes very expensive for instance. This system could be used for decentralized electricity supply or in an area with no electric grid. In order to evaluate the feasibility of a Compressed Air Energy Storage system coupled to a photovoltaic plant and a building that represents a reduced power demand, a numerical model that reflects the instant behaviour has been built. The system is composed of a photovoltaic power plant, an air compression system, a storage vessel, an expansion module, a power grid and a building. The inputs used are, on the one hand, the climate data such as ambient temperature and the global solar irradiation and, on the other hand, the load curve of a building or of the group of buildings, which has to be supplied by electricity. The overall system optimization has then been performed after having done a sensitivity analysis of the key parameters. This optimization allows us to find the most suitable size for each component of the system: compressor, tank size and photovoltaic area. Abstract One of the handicaps of the large-scale integration of solar energy is due to its variability and its intermittency. The main way to overcome this issue is the energy storage technology. Knowing the high cost of batteries and their impact on the environment, we simulate a storage system based on compressed air and acting as a battery system. The CAES consists in storing the air at a high pressure in a tank during the period when the energy source is abundant, i.e., cheap, or when the energy demand is low. The compressed air is later expanded through an air turbine which generates electricity during the high demand periods, i.e. when the energy source becomes very expensive for instance. This system could be used for decentralized electricity supply or in an area with no electric grid. In order to evaluate the feasibility of a Compressed Air Energy Storage system coupled to a photovoltaic plant and a building that represents a reduced power demand, a numerical model that reflects the instant behaviour has been built. The system is composed of a photovoltaic power plant, an air compression system, a storage vessel, an expansion module, a power grid and a building. The inputs used are, on the one hand, the climate data such as ambient temperature and the global solar irradiation and, on the other hand, the load curve of a building or of the group of buildings, which has to be supplied by electricity. The overall system optimization has then been performed after having done a sensitivity analysis of the key parameters. This optimization allows us to find the most suitable size for each component of the system: compressor, tank size and photovoltaic area
Trouble du spectre de l'autisme (TSA) à la Réunion: relation entre l'intensité du trouble et l'environnement socio-économique familial
No full textIntroduction : Autism includes a spectrum of various disorders, evolving differently from one subject to another, according to identified individual factors and not very well-known environmental ones. Existing longitudinal studies research the influence of therapeutic interventions. Our study aims to find a relationship between the intensity of the disorder and the socioeconomic environment of the child. Method : Our cross-sectional and analytical study was based on a sociometric questionnaire with parents of children aged from 5 to 12 years old, diagnosed with ASD at CRIA Réunion/Mayotte from 2007 to 2017. The results were related to the retrospective evaluation data (ADOS, language level, intelligence quotient). Results : 96 parents answered the questionnaire. The results showed a significant relationship between the intensity of the disorder and the level of education of the parents and with the household's average income level. Thus, significant differences in language level and intelligence quotient were also found according to the socio-professional categories of parents. Conclusion : This study suggests the influence of socioeconomic factors on the intensity of autism, with a more intense intellectual and language deficit among disadvantaged social categories. However, our study was geographically restricted to a single department, and to a limited number of parental responses. These results motivate other cohort studies or large scale follow-up to confirm or refute this influence of the social environment. Our results raise the issue of social inequalities in health and accessibility to care that may influence the national policy of care for autism.Introduction : L'autisme inclut un spectre de troubles variés, évoluant différemment d'un sujet à l'autre, selon des facteurs individuels identifiés et environnementaux peu connus. Les études longitudinales existantes étudient l'influence des interventions thérapeutiques. Notre étude avait pour objectif de rechercher une relation entre l'intensité du trouble et l'environnement socio-économique de l'enfant. Méthode : Notre étude transversale et analytique était basée sur un questionnaire sociométrique auprès des parents d'enfants, de 5 à 12 ans, diagnostiqués TSA au CRIA Réunion/Mayotte de 2007 à 2017. Les résultats ont été mis en relation avec les données rétrospectives de l'évaluation (ADOS, niveau de langage, quotient intellectuel). Résultats : 96 parents ont répondu au questionnaire. Les résultats ont montré une relation significative entre l'intensité du trouble et le niveau d'étude moyen des parents ainsi que le niveau de revenu moyen de foyer. Des écarts significatifs de niveau de langage et quotient intellectuel étaient constatés selon la catégorie socio-professionnelle des parents. Conclusion :Cette étude suggère l'influence du statut socio-économique familial sur l'intensité de l'autisme, avec un déficit intellectuel et de langage plus intense chez les catégories sociales défavorisés. Notre étude était restreinte géographiquement, et à un nombre limité de réponses. Ces résultats motivent à réaliser d'autres études à grande échelle pour confirmer ou infirmer cette influence de l'environnement social. Nos résultats soulèvent la question des inégalités sociales de santé et d'accessibilité aux soins pouvant influencer la politique nationale de prise en charge du TSA
A Critical Review of Edge and Fog Computing for Smart Grid Applications
No full textPart 4: Local Technical PapersInternational audienceSmart grid and cloud computing architectures have been perfectly suiting each other naturally. As a result, over the years cloud computing architectures have dominated the implementations of smart grid applications to address computing needs. However, due to continuing additions of heterogeneous (sensing and actuating) devices, emergence of Internet of Things (IoT), and massive amount of data collected across the grids for analytics, have contributed to the complexity of smart grids, making cloud computing architectures no longer suitable to provide smart grid services effectively. Edge and Fog computing approaches have relieved the cloud computing architectures of problems related to network congestion, latency and locality by shift of control, intelligence and trust to the edge of the network. In this paper, a systematic literature review is used to explore the research trend of the actual implementations of edge and fog computing for smart grid applications. A total of 70 papers were reviewed from the popular digital repositories. The study has revealed that, there is significant increase in the number of smart grid applications that have exploited the use edge and fog computing approaches. The study also shows that, considerable number of the smart grid applications are related to energy optimizations and intelligent coordination of smart grid resources. There are also challenges and issues that hinder smooth adoption of edge and fog computing for smart grid applications, which include security, interoperability and programming models
: Visuelle und literarische Darstellungen und ihre didaktischen Herausforderungen für den DaF-Unterricht
No full textIl s'agit d'une introduction à l'histoire du portage coloniale qui est destinée à faciliter l'utilisation d'un atelier didactique conçu pour des tables numériques qui voyagent entre différents collèges et lycées à l'Ile de La Réunion
Phosphorylation of the VAR2CSA extracellular region is associated with enhanced adhesive properties to the placental receptor CSA
No full textInternational audiencePlasmodium falciparum is the main cause of disease and death from malaria. P. falciparum virulence resides in the ability of infected erythrocytes (IEs) to sequester in various tissues through the interaction between members of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesin family to various host receptors. Here, we investigated the effect of phosphorylation of variant surface antigen 2-CSA (VAR2CSA), a member of the PfEMP1 family associated to placental sequestration, on its capacity to adhere to chondroitin sulfate A (CSA) present on the placental syncytium. We showed that phosphatase treatment of IEs impairs cytoadhesion to CSA. MS analysis of recombinant VAR2CSA phosphosites prior to and after phosphatase treatment, as well as of native VAR2CSA expressed on IEs, identified critical phosphoresidues associated with CSA binding. Site-directed mutagenesis on recombinant VAR2CSA of 3 phosphoresidues localised within the CSA-binding region confirmed in vitro their functional importance. Furthermore, using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein-9 nuclease (CRISPR/Cas9), we generated a parasite line in which the phosphoresidue T934 is changed to alanine and showed that this mutation strongly impairs IEs cytoadhesion to CSA. Taken together, these results demonstrate that phosphorylation of the extracellular region of VAR2CSA plays a major role in IEs cytoadhesion to CSA and provide new molecular insights for strategies aiming to reduce the morbidity and mortality of PM
