Quantifying sediment mass redistribution from joint time-lapse gravimetry and photogrammetry surveys

The accurate quantification of sediment mass redistribution is central to the study of surface processes, yet it remains a challenging task. Here we test a new combination of terrestrial gravity and drone photogrammetry methods to quantify sediment mass redistribution over a 1 km2 area. Gravity and photogrammetry are complementary methods. Indeed, gravity changes are sensitive to mass changes and to their location. Thus, by using photogrammetry data to constrain this location, the sediment mass can be properly estimated from the gravity data. We carried out three joint gravimetry–photogrammetry surveys, once a year in 2015, 2016 and 2017, over a 1 km^2 area in southern Taiwan, featuring both a wide meander of the Laonong River and a slow landslide. We first removed the gravity changes from non-sediment effects, such as tides, groundwater, surface displacements and air pressure variations. Then, we inverted the density of the sediment with an attempt to distinguish the density of the landslide from the density of the river sediments. We eventually estimate an average loss of 3.7 \ub1 0.4  7 10^9 kg of sediment from 2015 to 2017 mostly due to the slow landslide. Although the gravity devices used in this study are expensive and need week-long surveys, new instrumentation currently being developed will enable dense and continuous measurements at lower cost, making the method that has been developed and tested in this study well-suited for the estimation of erosion, sediment transfer and deposition in landscapes

Modulation of NK cell activation by exogenous calcium from alginate dressings in vitro

Natural Killer (NK) cells participate in the defense against infection by killing pathogens and infected cells and secreting immuno-modulatory cytokines. Defects in NK cell activity have been reported in obese, diabetic, and elderly patients that are at high risk of developing infected chronic wounds. Calcium alginate dressings are indicated for the debridement during the inflammatory phase of healing. Since calcium ions are major activators of NK cells, we hypothesized that these dressings could enhance NK functions, as investigated in vitro herein. Primary human blood NK cells were freshly-isolated from healthy volunteers and exposed to conditioned media (CM) from two alginate dressings, Algosteril® (ALG, pure Ca2+ alginate) and Biatain® Alginate (BIA, Ca2+ alginate with CMC), in comparison with an exogenous 3mM calcium solution. Our results demonstrated that exogenous calcium and ALG-CM, but not BIA-CM, induced NK cell activation and enhanced their capacity to kill their targets as a result of increased degranulation. NK cell stimulation by ALG depended on the influx of extracellular Ca2+via the SOCE Ca2+ permeable plasma membrane channels. ALG-CM also activated NK cell cytokine production of IFN-γ and TNF-α through a partly Ca2+-independent mechanism. This work highlights the non-equivalence between alginate dressings for NK cell stimulation and shows that the pure calcium alginate dressing Algosteril® enhances NK cell cytotoxic and immuno-modulatory activities. Altogether, these results underline a specific property of this medical device in innate defense that is key for the cutaneous wound healing process

Impact des mutations TET2/IDH sur les populations lymphocytaires dans les Syndromes Myélodysplasiques

Myelodysplastic syndrome (MDS) is a group of heterogeneous clonal disorders arising in the bone marrow (BM). MDS evolution is dominated by the risk of progression into acute myeloid leukemia (AML). A majority of MDS patients harbors somatic mutations in genes encoding factors involved in epigenetic regulation pathways including TET2 and IDH1/2. Those mutations have been also found in patients with clonal hematopoiesis of indeterminate potential (CHIP), a preleukemic state with a high incidence of evolving into MDS. However, mechanisms of progression from CHIP to MDS and later AML remain unknown and may implicate disruption of the anti-tumor immunosurveillance. Among immune cells in charge of the anti-tumor response, Natural Killer (NK) cells are key players to eliminate leukemic cells. However, at diagnosis of MDS, impaired NK cell's phenotype and function with a reduction of cytotoxicity and cytokine release has been described. In addition, 10 to 30% of MDS patients show autoimmune disorders (SIAD) potentially associated to T-cells perturbations. In this thesis, the results showed the association between TET2/IDH mutations and the presence of SIAD in patients with MDS. TET2/IDH mutations were also associated with the expression of immune checkpoint receptors on CD8+ T lymphocytes. In parallel, we observed for the first time that MDS patient's NK cells can harbor TET2/IDH mutations. These mutations were associated with reduced expression of key factors for NK function, including KIR receptors and intracellular perforin and suggest a deregulation of the anti-tumor NK-cell response. In conclusion, my results put in light the major role of the TET2/IDH-based DNA demethylation pathway in regulating T and NK lymphocytes and underlined the impact of their mutations in the development of MDS and its complications.Les Syndrome Myélodysplasique (SMD) sont des hémopathies myéloïdes clonales affectant la moelle osseuse, pouvant évoluer en Leucémie Aigue Myéloïde. Des mutations somatiques dans les gènes impliqués dans la méthylation de l'ADN (TET2, IDH1, IDH2 et DNMT3a) sont fréquemment retrouvées chez les patients atteints de SMD. Ces mutations sont aussi retrouvées dans les cellules souches hématopoïétiques d'individus sains âgés, phénomène nommé hématopoïèse clonale de signification indéterminée (CHIP), engageant un risque élevé d'évolution en SMD. Cependant, les mécanismes de progression de la CHIP vers le SMD sont mal connus et pourraient impliquer des défauts de l'immunosurveillance antitumorale, notamment par les cellules Natural Killer (NK). De plus, environ 25% des patients atteints de SMD développent des maladies auto-immunes ou des maladies inflammatoires systémiques (SIAD) potentiellement associées à des perturbations immunitaires, notamment des lymphocytes T. Mes travaux visent à déterminer l'impact des mutations TET2/IDH sur la survenue de SIAD et la progression leucémique en étudiant les populations lymphocytaires T ou NK. Les résultats montrent l'association entre ces mutations et la présence de SIAD chez les patients atteints de SMD. Les mutations TET2/IDH sont aussi associées à l'expression de récepteurs de points de contrôles immunitaires sur les lymphocytes T CD8+. De plus, nous avons observé pour la première fois la présence de mutations TET2/IDH dans les cellules NK. Ces mutations sont associées à une réduction de l'expression de facteurs clefs pour la fonction NK, notamment les récepteurs KIR et la perforine intracellulaire. En conclusion, mes résultats révèlent le rôle majeur de la protéine TET-2 dans la régulation des lymphocytes T et NK et soulignent l'impact de ses mutations dans le développement de la maladie SMD et de ses complications

Impact of TET2/IDH mutations on lymphocytes populations of myelodysplastic syndromes

Les Syndrome Myélodysplasique (SMD) sont des hémopathies myéloïdes clonales affectant la moelle osseuse, pouvant évoluer en Leucémie Aigue Myéloïde. Des mutations somatiques dans les gènes impliqués dans la méthylation de l'ADN (TET2, IDH1, IDH2 et DNMT3a) sont fréquemment retrouvées chez les patients atteints de SMD. Ces mutations sont aussi retrouvées dans les cellules souches hématopoïétiques d'individus sains âgés, phénomène nommé hématopoïèse clonale de signification indéterminée (CHIP), engageant un risque élevé d'évolution en SMD. Cependant, les mécanismes de progression de la CHIP vers le SMD sont mal connus et pourraient impliquer des défauts de l'immunosurveillance antitumorale, notamment par les cellules Natural Killer (NK). De plus, environ 25% des patients atteints de SMD développent des maladies auto-immunes ou des maladies inflammatoires systémiques (SIAD) potentiellement associées à des perturbations immunitaires, notamment des lymphocytes T. Mes travaux visent à déterminer l'impact des mutations TET2/IDH sur la survenue de SIAD et la progression leucémique en étudiant les populations lymphocytaires T ou NK. Les résultats montrent l'association entre ces mutations et la présence de SIAD chez les patients atteints de SMD. Les mutations TET2/IDH sont aussi associées à l'expression de récepteurs de points de contrôles immunitaires sur les lymphocytes T CD8+. De plus, nous avons observé pour la première fois la présence de mutations TET2/IDH dans les cellules NK. Ces mutations sont associées à une réduction de l'expression de facteurs clefs pour la fonction NK, notamment les récepteurs KIR et la perforine intracellulaire. En conclusion, mes résultats révèlent le rôle majeur de la protéine TET-2 dans la régulation des lymphocytes T et NK et soulignent l'impact de ses mutations dans le développement de la maladie SMD et de ses complications.Myelodysplastic syndrome (MDS) is a group of heterogeneous clonal disorders arising in the bone marrow (BM). MDS evolution is dominated by the risk of progression into acute myeloid leukemia (AML). A majority of MDS patients harbors somatic mutations in genes encoding factors involved in epigenetic regulation pathways including TET2 and IDH1/2. Those mutations have been also found in patients with clonal hematopoiesis of indeterminate potential (CHIP), a preleukemic state with a high incidence of evolving into MDS. However, mechanisms of progression from CHIP to MDS and later AML remain unknown and may implicate disruption of the anti-tumor immunosurveillance. Among immune cells in charge of the anti-tumor response, Natural Killer (NK) cells are key players to eliminate leukemic cells. However, at diagnosis of MDS, impaired NK cell's phenotype and function with a reduction of cytotoxicity and cytokine release has been described. In addition, 10 to 30% of MDS patients show autoimmune disorders (SIAD) potentially associated to T-cells perturbations. In this thesis, the results showed the association between TET2/IDH mutations and the presence of SIAD in patients with MDS. TET2/IDH mutations were also associated with the expression of immune checkpoint receptors on CD8+ T lymphocytes. In parallel, we observed for the first time that MDS patient's NK cells can harbor TET2/IDH mutations. These mutations were associated with reduced expression of key factors for NK function, including KIR receptors and intracellular perforin and suggest a deregulation of the anti-tumor NK-cell response. In conclusion, my results put in light the major role of the TET2/IDH-based DNA demethylation pathway in regulating T and NK lymphocytes and underlined the impact of their mutations in the development of MDS and its complications

Synthesis of a Stable and High-Concentration BaHf_xTi_1−xO₃ Sol–Gel for High Electromechanical Performance of Bulk Ceramics

Lead-based materials are widely used in piezoceramics due to their high electromechanical properties. However, due to environmental protection and sustainable development, the use of the toxic element lead (Pb) in electronic devices is strictly restricted, therefore requiring the rapid development of piezoelectric-based devices with lead-free ceramics. In this context, a lead-free doped barium titanate was studied with a dual objective. First, a new sol–gel method to synthesize Hf4+-doped BaHfxTi1−xO (BHT) with x = 0.05, 0.075, and 0.10 is presented. Such BHT sols were prepared at high concentrations of up to 1 M. Dilution in ethylene glycol allowed parameters (viscosity, colloid sizes, etc.) to be controlled, which ensured a time-stable sol for several months at room temperature. Second, densified bulk ceramics with attrited powders were obtained from these sols and showed very good electromechanical properties, with a thickness coupling factor of kt = 47% (BaHf0.05Ti0.95O3 sintered at 1500 °C/6 h). These results are a first step that will allow the processing of lead-free piezoelectric thick films using a sol–gel composite method for vibrational energy harvesting applications

Delineation of aquifer boundary by two vertical superconducting gravimeters in a karst hydrosystem, France

Mass distribution on Earth is continuously changing due to various physical processes beneath the Earth's surface or on the surface. Some of the primary sources for these mass displacements are tidal forces, atmospheric and oceanic loading, and seasonal changes in continental water distribution. The development of relative cryogenic gravimeters, the Superconducting Gravimeters (SGs), has made it possible to characterize and monitor such mass variations at orders of magnitudes as small as a few nm/s 2 (1 nm/s² ~ 10-10 g where g is the mean gravity at the Earth's surface). Our study focuses on the hydrodynamics of the 900 m thick unsaturated zone of the low-noise underground research laboratory (Laboratoire Souterrain à Bas Bruit, LSBB) located in Rustrel (France) using a unique configuration of two SGs vertically arranged 520 m depth apart. The installation of an SG (iGrav31) at the site surface several years afte

Delineation of Aquifer Boundary by Two Vertical Superconducting Gravimeters in a Karst Hydrosystem, France

Mass distribution on Earth is continuously changing due to various physical processes beneath the Earth\u27s surface or on the surface. Some of the primary sources for these mass displacements are tidal forces, atmospheric and oceanic loading, and seasonal changes in continental water distribution. The development of relative cryogenic gravimeters, the Superconducting Gravimeters (SGs), has made it possible to characterize and monitor such mass variations at orders of magnitudes as small as a few nm/s2 (1\ua0nm/s2–10–10\ua0g where g is the mean gravity at the Earth’s surface). Our study focuses on the hydrodynamics of the 900\ua0m thick unsaturated zone of the low-noise underground research laboratory (Laboratoire Souterrain \ue0 Bas Bruit, LSBB) located in Rustrel (France) using a unique configuration of two SGs vertically arranged 520\ua0m depth apart. The installation of an SG (iGrav31) at the site surface several years after installing the first (iOSG24) inside a tunnel has provided several new insights into the understanding of the hydrological processes occurring in the LSBB. By comparing differential and residual gravity time-series together with global hydrological loading models, we find that most water-storage changes occur in the unsaturated zone between both SGs. The misfit between the observed gravity time-series and the gravity effect corresponding to local hydrological contribution calculated from global hydrological models can be explained by large lateral fluxes and rapid runoff occurring in the LSBB site. Finally, we implement a rectangular prism method to compute forward gravity responses to water storage changes for a homogeneous water-layer following the site topography using a 5-m digital elevation model. In particular, we analyse the sensitivity of the differential record from both SGs to the extent and depth of the water storage changes by computing the corresponding 2D admittances. This gravity difference is sensitive to an extension up to about 2500\ua0m laterally before tending towards an asymptotic value corresponding to the Bouguer plate approximation. We show that the zone of water-storage changes that best fits observed differential gravity signal is located at depths larger than 500\ua0m (below iOSG24). This fitting is improving when the integration radius increases with depth. This is the first time that hydrological processes are investigated when the baseline configuration of two SGs is vertical

Water storage changes as a marker for base flow generation processes in a tropical humid basement catchment (Benin): Insights from hybrid gravimetry

International audienceIn basement catchments of subhumid West Africa, base flow is the main component of annual streamflow. However, the important heterogeneity of lithology hinders the understanding of base flow generation processes. Since these processes are linked with water storage changes (WSCs) across the catchment, we propose the use of hybrid gravity data in addition to neutron probe-derived water content and water levels to monitor spatiotemporal WSC of a typical crystalline basement headwater catchment (16 ha) in Benin. WSC behaviors are shown to provide insights into hydrological processes in terms of water redistribution toward the catchment outlet. Hybrid gravimetry produces gravity change observations from time-lapse microgravity surveys coupled with gravity changes monitored at a base station using a supercon-ducting gravimeter and/or an absolute gravimeter. A dense microgravity campaign (70 surveys of 14 stations) covering three contrasted years was set up with a rigorous protocol, leading to low uncertainties (<2.5 lGal) on station gravity determinations (with respect to the network reference station). Empirical orthogonal function analyses of both gravity changes and WSCs from neutron probe data show similar spatial patterns in the seasonal signal. Areas where storage and water table show a capping behavior (when data reach a plateau during the wet season), suggesting threshold-governed fast subsurface redistribution, are identified. This observed storage dynamics, together with geological structures investigated by electrical resistivity tomogra-phy and drill log analysis, make it possible to derive a conceptual model for the catchment hydrology