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A Long‐Term Ecological Research Data Set From the Marine Genetic Monitoring Program ARMS ‐ MBON 2018–2020
No full textInternational audienceMolecular methods such as DNA/eDNA metabarcoding have emerged as useful tools to document the biodiversity of complex communities over large spatio‐temporal scales. We established an international Marine Biodiversity Observation Network (ARMS‐MBON) combining standardised sampling using autonomous reef monitoring structures (ARMS) with metabarcoding for genetic monitoring of marine hard‐bottom benthic communities. Here, we present the data of our first sampling campaign comprising 56 ARMS units deployed in 2018–2019 and retrieved in 2018–2020 across 15 observatories along the coasts of Europe and adjacent regions. We describe the open‐access data set (image, genetic and metadata) and explore the genetic data to show its potential for marine biodiversity monitoring and ecological research. Our analysis shows that ARMS recovered more than 60 eukaryotic phyla capturing diversity of up to ~5500 amplicon sequence variants and ~1800 operational taxonomic units, and up to ~250 and ~50 species per observatory using the cytochrome c oxidase subunit I (COI) and 18S rRNA marker genes, respectively. Further, ARMS detected threatened, vulnerable and non‐indigenous species often targeted in biological monitoring. We show that while deployment duration does not drive diversity estimates, sampling effort and sequencing depth across observatories do. We recommend that ARMS should be deployed for at least 3–6 months during the main growth season to use resources as efficiently as possible and that post‐sequencing curation is applied to enable statistical comparison of spatio‐temporal entities. We suggest that ARMS should be used in biological monitoring programs and long‐term ecological research and encourage the adoption of our ARMS‐MBON protocols
Subaltern Urbanization and rural-urban linkages in India
No full textInternational audienceThis paper explores the specificities of the urbanization processes in India, which draws upon its dense and historically established network of settlements of various sizes. Besides the large-scale metropolises, India's urban landscape is dotted with numerous small towns and large villages with different economic structures and a varied set of basic services. This can be attributed to both a slow process of metropolitanization of the economy and vernacular agencies of smaller settlements, which have historically served the diverse consumer base of rural and urban India. Based on the analysis of a large-scale, granular socio-economic and spatial dataset, this chapter explores the economic structure and living conditions of these smaller settlements in India, with reference to their locations to big cities, varied capacities and governance structures. It also attempts to correlate these issues with the larger question of rural-urban linkages, using different proxy indicators like commuting and land-transactions. The chapter concludes with the idea of subaltern urbanization, materializing in highly varied regions across India that warrant further exposure and analysis
Les défis d'une réforme de la santé au Sénégal : analyse qualitative de la départementalisation des mutuelles de santé
No full textTraduction de l'article publié en anglaisInternational audiencePendant une décennie, le Sénégal a organisé des mutuelles de santé au niveau communal. En réponse à leur échec, le gouvernement a lancé une réforme en 2022. Toutes les mutuelles communautaires dirigées par des bénévoles sont sur le point de disparaître au profit d'une seule mutuelle départementale dirigée par des professionnels. Cette étude qualitative vise à comprendre les enjeux de la mise en oeuvre de cette réforme. Après une longue immersion sur le terrain au niveau national et local (2020-2023), nous avons utilisé 27 entretiens approfondis pour étudier le rôle des acteurs sociaux, les idées, la dynamique du pouvoir et le contexte. Les partisans de la réforme soutiennent que les conflits d'intérêts découlant de la dynamique du pouvoir expliquent la résistance. Les opposants affirment que le public soutient le sauvetage de leurs mutuelles communautaires défaillantes. Les défis de la résistance tournent autour des statuts, des questions de pouvoir et du contrôle des ressources financières. Bien que les acteurs aient pris du temps à prendre une décision, le processus est parfois perçu comme forcé et hâtif. Cependant, la plupart des parties prenantes n'avait guère d'autre choix que de l'accepter.</div
Metasomatic Alteration of Type 3 Ordinary and Carbonaceous Chondrites
No full textInternational audienceAbstract Metasomatism refers to the process during which a pre-existing rock undergoes compositional and mineralogical transformations associated with chemical reactions triggered by the reaction of fluids which invade the protolith. It changes chemical compositions of minerals, promotes their dissolution and precipitation of new minerals. In this paper, we review metasomatic alteration of type 3 ordinary (H, L, LL) and carbonaceous (CV, CO, CK) chondrites, including ( i ) secondary mineralization, ( ii ) physicochemical conditions, ( iii ) chronology ( 53 Mn- 53 Cr, 26 Al- 26 Mg, 129 I- 129 Xe) of metasomatic alteration, ( iv ) records of metasomatic alteration in H, O, N, C, S, and Cl isotopic systematics, ( v ) effects of metasomatic alteration on O- and Al-Mg-isotope systematics of primary minerals in chondrules and refractory inclusions, and ( vi ) sources of water ices in metasomatically altered CV, CO, and ordinary chondrites, and outline future studies
Rayonnement électromagnétique VHF post-arc en retour dans des éclairs nuage-sol du bassin Méditerranéen nord-ouest
No full textInternational audienceWe investigate properties of the electromagnetic activity following the first lightning return stroke (RS), using concurrent observations from the SLAVIA (Shielded Loop Antenna with a Versatile Integrated Amplifier) sensor, the SAETTA (Suivi de l'Activité Electrique Tridimensionnelle Totale de l'Atmosphère) Lightning Mapping Array (LMA) and the METEORAGE LF (low-frequency) network in the Corsica region. From the data collected between September and December 2015, we selected 66 negative cloud-to-ground (−CG) and 26 positive cloud-to-ground (+CG) lightning flashes in the north-western Mediterranean region. In the SAETTA data, we observe a decrease in the very high frequency (VHF) radiation rate and the VHF power, as recorded within a typical 80 µs time window at the LMA stations, immediately after the RS pulse in 59 −CG flashes. Contrastingly, we show that all examined +CG flashes exhibit a rapid increase in the VHF radiation rate and the VHF power immediately after the RS. We suggest a possible explanation of this phenomenon by considering the step-like propagation of a negative part of the bidirectional leader starting at the top end of the positive lightning channel inside the thundercloud, emitting electromagnetic radiation across a broad frequency spectrum
Ultrafast dynamics of hot carriers: Theoretical approaches based on real-time propagation of carrier distributions
No full textInternational audienceIn recent years, computational approaches which couple density functional theory (DFT)-based description of the electron–phonon and phonon–phonon scattering rates with the Boltzmann transport equation have been shown to obtain the electron and thermal transport characteristics of many 3D and 2D semiconductors in excellent agreement with experimental measurements. At the same time, progress in the DFT-based description of the electron–phonon scattering has also allowed to describe the non-equilibrium relaxation dynamics of hot or photo-excited electrons in several materials, in very good agreement with time-resolved spectroscopy experiments. In the latter case, as the time-resolved spectroscopy techniques provide the possibility to monitor transient material characteristics evolving on the femtosecond and attosecond time scales, the time evolution of photo-excited, nonthermal carrier distributions has to be described. Similarly, reliable theoretical approaches are needed to describe the transient transport properties of devices involving high energy carriers. In this review, we aim to discuss recent progress in coupling the ab initio description of materials, especially that of the electron–phonon scattering, with the time-dependent approaches describing the time evolution of the out-of-equilibrium carrier distributions, in the context of time-resolved spectroscopy experiments as well as in the context of transport simulations. We point out the computational limitations common to all numerical approaches, which describe time propagation of strongly out-of-equilibrium carrier distributions in 3D materials, and discuss the methods used to overcome them
Coupling Infrared Isotopic Gas Analysis and Thermal Ramped Analysis to Characterise Soil Organic and Inorganic Carbon
No full textInternational audienceStudying the soil organic and inorganic carbon (SOC and SIC) dynamics is essential to assess the carbon (C) sequestration potential of calcareous soils. Isotopic signatures (δ 13 C) are used to assess the C origin of SOC or SIC. However, as measuring SOC and SIC contents, measuring δ 13 C SOC and δ 13 C SIC on a non‐pretreated aliquot remains a challenge. Thermal analyses, like the Rock‐Eval (RE) analysis, are promising to quantify SOC and SIC in a single analysis, but, to our knowledge, no development was conducted to assess δ 13 C SOC and δ 13 C SIC . We coupled a RE device to an isotopic gas analyser (Picarro) to continuously measure δ 13 C CO2 and approach δ 13 C SOC and δ 13 C SIC . We hypothesised that different carbonate mineralogies and/or crystal sizes in SIC involve fluctuations of the δ 13 C CO2 . Two calcareous soils, a lithogenic (calcite) and a biogenic (snail shell) carbonate, and five calcite/shell mixes were analysed with the RE‐Picarro setup. Two distinct δ 13 C CO2 values were obtained before and after 650°C and were consistent with the δ 13 C SOC and δ 13 C SIC obtained by EA‐IRMS. The fluctuations of δ 13 C CO2 above 650°C were higher with calcite/shell mixes than with pure carbonates. A δ 13 C CO2 fluctuation > ± 0.2‰ could be a pertinent indicator to detect mixes of carbonate with different δ 13 C in soils. The RE‐Picarro setup is promising to assess SOC and SIC contents, δ 13 C SOC and δ 13 C SIC and detect mixes of carbonate with different origin on a non‐pretreated aliquot. Development is needed (i) on more soil and carbonate samples and (ii) to improve the precision and accuracy of the RE‐Picarro setup
Genomics and morphometry of herbarium specimens elucidate the origin of the Cape Verde date palm ( Phoenix atlantica A.Chev.) and highlight its agronomic potential
No full textInternational audienceSocietal Impact Statement As climate change accelerates, breeding resilient crops is urgent. The date palm ( Phoenix dactylifera L.), a crucial 18 billion USD fruit crop, underpins North African and West Asian oasis agroecosystems. This study investigates the genetics and morphology of its closest wild relative, the endemic and endangered Cape Verde date palm ( Phoenix atlantica A.Chev.). We reveal that the latter originated through a feralisation process from domesticated date palms, evolving back into a wild state with unique genetic diversity. This highlights the need to protect its distinctiveness and opens the possibility of enhancing date palm resilience through its inclusion in breeding programs. Summary The date palm ( Phoenix dactylifera L.). is a major crop but its sustainability is threatened by climate change. This challenge could be mitigated by breeding with wild relatives or feral populations. The endangered and endemic Cape Verde date palm ( Phoenix atlantica A.Chev.) is thought to be among the closest relatives of the date palm, but its origin and taxonomic status remain unclear, with studies having recovered it either as a separate species or a feral date palm. Better understanding the differentiation of P. atlantica and P. dactylifera is needed to fully unlock the potential of the Cape Verde date palm as a candidate for date palm improvement. In this study, we employ an integrative approach to clarify the origin of P. atlantica . Specifically, we investigate the phylogenetic placement, genetic structure, and seed morphology of P. atlantica by generating extensive genomic and seed morphology datasets from expert‐verified historical and modern specimens of Phoenix , including the type specimen of P. atlantica . Our findings indicate that P. atlantica is monophyletic but nested within P. dactylifera . Its genetic diversity overlaps substantially but not completely with North African date palm varieties, and its seeds share characteristics with those of cultivated and feral date palms, notably elongation, a trait linked to domestication. These results suggest that P. atlantica may be an incipient species that originated from a date palm feralisation event. We emphasise the need for conserving its natural genetic variation and the traditional knowledge associated with its name to support breeding programs.La mejora de cultivos adaptados al cambio climático es urgente. La palmera datilera ( Phoenix dactylifera L.), un cultivo frutal crucial valorado en 18 mil millones de dólares, sustenta los agroecosistemas de los oasis del norte de África y Asia occidental. Este estudio investiga la genética y la morfología de su pariente silvestre más cercano, la palmera datilera de Cabo Verde ( Phoenix atlantica A.Chev.), endémica y en peligro de extinción. Revelamos que esta última se originó a través de un proceso de feralización a partir de palmeras datileras domesticadas, y evolucionó nuevamente a un estado silvestre con una diversidad genética única. Esto resalta la necesidad de proteger su carácter distintivo y abre la posibilidad de mejorar la resiliencia al cambio climático de la palmera datilera mediante su inclusión en programas de mejora de cultivos.Alors que le changement climatique s'accélère, il devient urgent de sélectionner des cultures résilientes. Le palmier dattier ( Phoenix dactylifera L.), une culture fruitière essentielle, évaluée à 18 milliards de dollars, constitue la base des agroécosystèmes oasiens d'Afrique du Nord et d'Asie de l'Ouest. Cette étude porte sur la génétique et la morphologie de son parent sauvage le plus proche, le palmier dattier du Cap‐Vert ( Phoenix atlantica A.Chev.), une espèce endémique et menacée. Nous révélons que ce dernier est issu d'un processus de féralisation à partir de palmiers dattiers domestiqués, retournés à l'état sauvage et ayant développés une diversité génétique unique, soulignant ainsi l'importance de préserver cette singularité et de l'intégrer aux programmes d'amélioration du palmier dattier.A melhoria de cultivos adaptadas às mudanças climáticas é urgente. A tamareira ( Phoenix dactylifera L.), uma cultura frutífera crucial avaliada em 18 mil milhões de dólares, sustenta os agroecossistemas dos oásis do Norte de África e da Ásia Ocidental. Este estudo investiga a genética e a morfologia do seu parente selvagem mais próximo, a endêmica e ameaçada de extinção tamareira de Cabo Verde ( Phoenix atlantica A.Chev.). Revelamos que esta última se originou através de um processo de feralização a partir de tamareiras domesticadas, evoluindo de volta para um estado selvagem com uma diversidade genética única. Isto destaca a necessidade de proteger sua distinção e abre a possibilidade de aumentar a resiliência da tamareira às mudanças climáticas por meio da inclusão em programas de melhoramento de cultivos
Challenges in the Definition of the Left Behind in International Migration Studies
No full textInternational audienceThe large differences in income per capita across countries imply that the occurrence of an international migration episode can have far-reaching implications also for the family members left behind, as international migrants typically share a substantial portion of their income gain through remittances sent back home. This chapter reviews the approaches adopted in the literature to define the individuals left behind. This critical and often data-constrained analytical choice can have significant implications for the econometric analysis of the effects of migration and remittances on non-migrant individuals and for comparing results found using different definitions. It discusses the existing wedge between the theoretical representation of migration decisions, which puts the family at center stage, and the empirical analysis, which mainly focuses on a narrower set of family members who co-resided with the migrant. The empirical literature mainly relies on three main approaches, defining the left behind as the members (i) of a remittance-recipient household, (ii) of a household reporting the migration of a former household member, or (iii) as the relatives of the migrant, e.g., spouse, parents or children. The chapter documents the variety of definitions applied in empirical analyses, discussing their implications and limitations. It also reviews some recent advances in the literature, which explore the endogeneity of household composition and family structure with the occurrence of an international migration episode.</div