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Paleo-Scours Within the Layered Sulfate-Bearing Unit at Gale Crater, Mars: Evidence for Intense Wind Erosion
No full textInternational audienceThe surface of modern Mars is largely shaped by wind, but the influence of past wind activity is less well constrained. Sedimentary rocks exposed in the lower foothills of Aeolis Mons, the central mound within Gale crater, record a transition from predominantly lacustrine deposition in the Murray formation to aeolian deposition in the Mirador formation. Here, we report a series of enigmatic decameter-wide, concave-up scour-and-fill structures within the Mirador formation and discuss their formation mechanisms. Using panoramic images of stratigraphy exposed in cliff faces acquired by the Curiosity rover, we map the extent, distribution and orientation of the scour-and-fill structures and document the sedimentary facies within and surrounding these structures. The scours are grouped into two classes: (A) scours with a simple, symmetric morphology and light-toned, draping infill; and (B) scours with lateral pinching and dark-toned infill. We find that the scour-enclosing environment is composed of planar, even-in-thickness laminations with a pin-stripe pattern which we interpret as wind-ripple strata formed within an aeolian sandsheet environment. Class B contains cm-scale cross-bedding and a wing-shaped feature making this scour-and-fill structure consistent with fluvial processes. We interpret scour fill of class A as an aeolian infill due to similarities with the surrounding sandsheet strata. The broad morphologies and distribution of class A are also consistent with the geometry of blowout structures formed by localized, enhanced wind deflation. These paleo-blowout structures occur clustered within the same stratigraphic interval, which may imply that they record an interval of intensified wind activity at Gale crater
Confined aquifers: a need for an adaptation of sustainability concepts
No full textInternational audienceConfined aquifers, distinguished by their large storage and long-term flow dynamics, are often overlooked in groundwater sustainability assessments and rely on frameworks developed for unconfined systems. Unlike unconfined aquifers, confined systems release water through the compressibility of the porous medium, without pore drainage. These properties lead to lower storativity and higher hydraulic diffusivity, resulting in different responses to hydraulic perturbations, such as pumping or recharge temporal variations. Addressing these differences is essential to develop tailored approaches for the sustainable management of confined aquifers, particularly in the context of balancing water supply for different competing demands with the environmental and socioeconomic impacts of abstraction. We develop a framework for the sustainable management of confined aquifers based on numerical models over synthetic cross sections of multi-layer flow systems. We explore the fundamental differences between confined and unconfined aquifers, particularly in terms of their hydraulic behaviour, response time to hydraulic perturbations, and the interactions with surrounding hydrogeological units. This modelling study also illustrates how confined aquifers indirectly interact with unconfined systems and surface water systems, through their connection via confining layers. A critical aspect of this work involves understanding the transient response of aquifers, which is governed by their hydraulic diffusivity and described by the concept of response time. Diffusivity governs the rate at which hydraulic disturbances propagate, and the response time describes the time required for the aquifer to reach a new equilibrium. Existing analytical formulations highlight the distinct behaviour of confined aquifers, particularly their faster response times compared to unconfined systems. However, for large-scale confined or mixed systems, response time scales may approach or even exceed those of unconfined aquifers with similar hydraulic properties and, generally, smaller extension. This underscores the importance of a proper delimitation of aquifer boundaries in the assessment of their response times. In practice, water sustainability policies are inherently scoped within site-specific areas and timeframes. Today, these policies must address increasing pressures from population growth, climate change, surface water quality issues, and other contributing factors. Groundwater models, which support management decisions, should include these factors through accurate conceptualizations of hydrogeological systems, evaluations of their response times, and scenario analyses. Through the adaptation of sustainability concepts for confined and mixed aquifer systems, this study contributes to the development of a framework that will support groundwater management strategies for confined aquifers and highlights their role as a valuable resource for long-term adaptation, emphasizing the need to protect and optimize their use in response to environmental and societal challenges
Scientific response to the 2021–2022 seismic swarm in the Monts Dore volcanic province (France): structural insights from punctual surveys (1/2)
No full textInternational audienceLong-dormant volcanic provinces remain excellent proxies in studying active edifices. The Monts Dore volcanic province (French Massif Central) has been recently the site of a unique seismic episode. Geophysical surveys were conducted at different horizontal and vertical spatial scales. Magnetic anomalies highlight mechanical heterogeneities consistent with the regional tectonic context. Low-conductive structures imaged suggest the presence of fluid rising along main paths at various depths. Although we cannot strictly exclude a purely tectonic explanation, our data seem to support the origin of seismicity as being linked to the injection of fluids at depth controlled by internal structural constraints
Avis sur la proposition d'inscription du site "La Loire des confluences" au titre de la convention internationale dite de "Ramsar" sur les zones humides
No full textInteractions between the perception of agri-environmental performances and multi-criteria evaluation based on crop model simulations in southwestern France
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Redox-Active Ligand Platforms for Spin-Crossover Materials: Influence of Halogen Substitution in Pt(II) and Ni(II) Hofmann-Type Frameworks
No full textInternational audienceWe report the synthesis and structural characterization of a series of halogen-based Hofmann clathrates having two different general formulas {Fe(Xa-pbpy+)2[μ2-Ma(CN)4]2·2H2O} (where Xa = Cl, Br, or I with Ma = Ni; Xa = Br or I with Ma = Pt) and {Fe(Xb-pbpy+)2(H2O)2[μ2-Mb(CN)4]·[Mb(CN)4]} (where Xb = F with Mb = Ni; Xb = Cl or F with Mb = Pt), by incorporating halogen-substituted bipyridinium derivatives as ligands. We demonstrate that halogen substitution and the choice of the tetracyanometalate bridge synergistically modulate the structural motifs and therefore magnetic properties. In addition, we show that the previously established Marcus theory-based model, describing the correlation between the ligand redox potential (influenced by the nature of the halogen) and the resulting crystal space group as well as spin crossover (SCO) temperature (T1/2) for a related series of Pt-based compounds, also extends to the Ni-based analogues. This confirms the general validity of the Marcus-type redox–SCO correlation across this family of Hofmann-type clathrates. Single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and Mössbauer spectroscopy confirm the structural and electronic divergence between staggered and layered architectures and establish a unified redox–structure–SCO relationship. These findings offer valuable insight into the rational design of multifunctional molecular materials
Is there a link between the acute stress response and the movement syndrome of a wild large herbivore?
No full textInternational audienceWhen faced with stressful situations, individuals differ in their behavioural and physiological responses depending on their behavioural type; that is, personality. For mobile organisms, movement is one of the primary responses to threats. Movement syndromes (i.e. suites of correlated movement traits) have been linked to individual differences in risk taking, resource acquisition and performance, and can influence the evolutionary trajectory of these behaviours. Often, standardized tests are used to identify behavioural types; however, behaviours evaluated in controlled settings might not accurately reflect behaviours expressed while free-ranging in the wild. Nonetheless, the acute stress response of an individual expressed during a test could be related to a stress-mitigating behaviour in natural conditions, such as movement. To address this question, we used a long-term monitored population of wild roe deer, Capreolus capreolus, to identify movement-related personality traits and investigate the existence of a movement syndrome. We then examined its link with among-individual differences in the acute stress response (rectal temperature, haematocrit, neutrophil/lymphocyte ratio and docility) expressed during capture and handling. Using GPS monitoring of up to 335 roe deer in a highly heterogenous landscape, we showed that risk-prone individuals (i.e. using riskier habitat and ranging closer to roads during daytime) were also more active, with a lower movement speed and larger home ranges. However, we only found weak support for a link at the among-individual level between an individual's movement syndrome and its stress response during controlled capture, although there was some indication that individuals with an attenuated physiological response to acute stress tended to take more risk when free-ranging. This lack of support might be explained by the fact that different traits reflect different dimensions of the stress response, or by the low number of replicates per individual for these traits. These findings highlight the complexity of interpreting stress responses in natural populations. (c) 2025 The Author(s). Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour
A recuperação das paisagens florestais é possível na Amazônia? Estudo de caso no município de Irituia, Nordeste do Pará
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616109/)International audienceThe Amazon provides numerous essential ecosystem services to societies at both local and global scales. Despite the forest's systemic importance, deforestation in the region has shown a growing trend, intensifying in recent years. However, in the municipality of Irituia, located in the Northeastern Pará Mesoregion, studies have shown that agroecological practices adopted by family farmers have significantly contributed to local forest recovery. This article analyzes the historical and spatial aspects that characterize and differentiate Irituia's agrarian system in relation to other municipalities in the region, with emphasis on deforestation and forest regeneration dynamics. Using a systemic and multi-scalar approach, the study involved document analysis, historical interviews, and remote sensing data covering the period from 1990 to 2020. The results indicate that, while the regional trajectory reveals a reduction in undisturbed humid forests and an increase in deforestation, Irituia follows a distinct path marked by forest regrowth processes. This trend intensified after 2010, as a result of sustainable practices promoted by family farmers over time, supported by social movements, institutions, and public policies. The study concludes that Irituia's experience represents a concrete alternative for productive restoration and environmental conservation, reaffirming the strategic role of family farming in reshaping Amazonian landscapes.A Amazônia desempenha inúmeros serviços ecossistêmicos fundamentais para as sociedades, em escala local e global. Apesar da importância sistêmica da floresta, o desmatamento nessa região vem apresentando uma tendência crescente, intensificando-se nos últimos anos. No entanto, no município de Irituia, situado na Mesorregião do Nordeste Paraense, estudos vêm demonstrando que práticas agroecológicas adotadas por agricultores familiares têm contribuído significativamente para a recuperação florestal local. Este artigo analisa os aspectos históricos e espaciais que caracterizam e diferenciam o sistema agrário de Irituia em relação aos demais municípios da região, com ênfase nas dinâmicas de desmatamento e recomposição florestal. A partir de uma abordagem sistêmica e multiescalar, foram utilizadas análises documentais, entrevistas históricas e dados de sensoriamento remoto, abrangendo o período de 1990 a 2020. Os resultados indicam que, enquanto a trajetória regional evidencia a redução das florestas úmidas não perturbadas e o avanço do desmatamento, Irituia apresenta um percurso diferenciado, marcado por processos de recrescimento florestal. Esse processo se intensificou a partir de 2010, resultante de práticas sustentáveis promovidas por agricultores familiares ao longo do tempo, com o apoio de movimentos sociais, instituições e políticas públicas. Conclui-se que a experiência de Irituia representa uma alternativa concreta de restauração produtiva e conservação ambiental, reafirmando o papel estratégico da agricultura familiar no redesenho das paisagens amazônicas
Explorations and surveys in the Taung and Karchat regions
No full textInternational audienceThe works of the MAI and MAFM have shown the strong interaction between the populations of ancient Sindh and Baluchistan regions (Quivron,2010). In the continuity of this work the MAFBI program, is analyzing the data with a new perspective since the restart of the fieldwork operations in Sindh (2014). This new gathered data is being confronted both to the former fieldwork data from Baluchistan and new data gathered through distant survey
Impact of temperature on survival, development and longevity of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Phnom Penh, Cambodia
No full textInternational audienceBackgroundAedes aegypti and Ae. albopictus are primary vectors of dengue virus in Cambodia, distributed throughout the country. Climate change is predicted to affect the relative density of these two species, but there is a lack of studies evaluating the impact of temperature on populations of these two species in this region. This study investigates the impact of temperature on the survival, development and longevity of Ae. aegypti and Ae. albopictus from populations collected in Phnom Penh, Cambodia.MethodsAedes aegypti and Ae. albopictus populations were collected in Phnom Penh. The experiment was conducted in a climatic chamber with temperatures ranging from 15 °C to 40 °C, with a 5 °C increment between each treatment. Bionomic parameters from the F2 egg hatching rate to the number of F3 eggs produced at each temperature treatment were measured.ResultsTemperature significantly influenced all life history traits of Ae. aegypti and Ae. albopictus. The highest egg hatching rates were observed at 25 °C for Ae. aegypti (97.97%) and 20 °C for Ae. albopictus (90.63%). Larvae of both species could not survive beyond the first stage at 40 °C. During immature stages, development time decreased at higher temperature (35 °C), but mortality was increased. Female longevity peaked at 25 °C for Ae. aegypti (66.7 days) and at 20 °C for Ae. albopictus (22.6 days), with males having significantly shorter lifespans. In addition, the optimal temperature for female survival is predicted higher in Ae. aegypti than in Ae. albopictus, at 27.1 °C and 24.5 °C, respectively. Wing length increased at lower temperatures, with Ae. aegypti consistently longer than Ae. albopictus at 15 °C and 35 °C. Blood-feeding rates were highest at 30 °C for Ae. aegypti (61.0%) and at 25 °C for Ae. albopictus (52.5%).ConclusionAedes albopictus appears better adapted to lower temperatures, whereas Ae. aegypti is better adapted to higher temperatures. Warmer temperatures accelerate mosquito development but also increased mortality and reduced adult longevity, which could influence their ability to transmit pathogens. These findings highlight the critical role of temperature in mosquito biology and emphasize the potential impact of climate change on dengue transmission dynamics in the future