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Inflammation is a complex physiological process triggered in response to harmful stimuli1. It involves cells of the immune system capable of clearing sources of injury and damaged tissues. Excessive inflammation can occur as a result of infection and is a hallmark of several diseases2–4. The molecular bases underlying inflammatory responses are not fully understood. Here we show that the cell surface glycoprotein CD44, which marks the acquisition of distinct cell phenotypes in the context of development, immunity and cancer progression, mediates the uptake of metals including copper. We identify a pool of chemically reactive copper(ii) in mitochondria of inflammatory macrophages that catalyses NAD(H) redox cycling by activating hydrogen peroxide. Maintenance of NAD+ enables metabolic and epigenetic programming towards the inflammatory state. Targeting mitochondrial copper(ii) with supformin (LCC-12), a rationally designed dimer of metformin, induces a reduction of the NAD(H) pool, leading to metabolic and epigenetic states that oppose macrophage activation. LCC-12 interferes with cell plasticity in other settings and reduces inflammation in mouse models of bacterial and viral infections. Our work highlights the central role of copper as a regulator of cell plasticity and unveils a therapeutic strategy based on metabolic reprogramming and the control of epigenetic cell states.

Several equations and their simplified versions already exist for estimating evapotranspiration. Still, the practical difficulty in using them is that they contain too many variables and empirical parameters including some non-atmospheric vegetation-based ones which may not be appropriate for all plant types. Therefore, a simple empirical equation is suggested here to approximately estimate evapotranspiration loss in a deterministic manner as a function of the green roof’s water content, ambient air temperature, wind speed, relative humidity, and total net radiation flux. For nonlinear processes such as evapotranspiration clearly, such deterministic estimates are not representative of the extreme values observed in evapotranspiration losses. Therefore, a universal multifractal-based simulation procedure is proposed here to improve such deterministic estimates, so that the simulated evapotranspiration loss has realistic intermittency and temporal scaling behaviour, while preserving its diurnal variability. KeywordsMultifractals, Non-linear geophysical systems, Cascade dynamics, Scaling, Hydrology, Meteorology.

Nature-based adaptation Solutions (NbaS) have become central elements for action on climate. With a wide range of forms across different ecosystems, NBaS are now recognized to mitigate the intensity and frequency of climate-related events, to buffer heat stress and to regulate altered hydrological cycles for instance.The LIFE ARTISAN project (Achieving Resiliency by Triggering Implementation of nature-based Solutions for climate Adaptation at a National scale) aims to promote the implementation of NbaS throughout the French territory (www.life-artisan.fr) in the framework of the National Plan for Climate Change Adaptation. For this purpose, many actions are carried out to facilitate the design, use, assessment and maintenance of NbaS: development of tools, trainings, grid of indicators, taking benefit from 10 pilot sites.This communication is particularly focused on the way in which the naturation of the urban environment can attenuate heat islands. It presents the thermo-hydric coupling carried out between the Multi-Hydro and Solène-Microclimate models. This new platform is able to simulate both water balance and energy budget to assess the performance of NbaS in stormwater management and microclimate mitigation at the urban project scale. This coupling, based on the evapotranspiration process, was validated by using observed data collected during the ANR EVNATURB project (https://hmco.enpc.fr/portfolio-archive/evnaturb/).Perspectives are proposed concerning schoolyards. These locations, often highly impervious, appear very relevant for setting up NbaS in order to create cooling islands, while having an educational aim.

While the importance of Nature-based Solutions for climate change adaptation (NbaS) is being increasingly acknowledged, this concept should be introduced in higher education. It looks particularly important for master's programs, because they usually lead to management jobs. Future graduates will therefore be required to make decisions in land use planning, urban planning, risk and resource management for example.Based on a survey questionnaire, several interviews and a text mining analysis of the Master’s contents, a first analysis was conducted to identify, localise and analyse the French Masters that presented links with NbaS related concepts. This analysis revealed that the notion of NbaS is far from being mastered. This might be caused by a conceptual misunderstanding of definitions.A combined analysis of the findings derived from this study and the results acquired within the framework of the European ARTISAN project (Achieving Resiliency by Triggering Implementation of nature-based Solutions for climate Adaptation at a National scale, www.life-artisan.fr), a training module dedicated to NbaS has been designed. Covering a wide spectrum of topics, it is composed of 8 courses of 3 hours: (i) Introduction to climate change, (ii) NbS and NbaS: from terminology to reality, (iii) Ecological engineering and multidisciplinary approach, (iv) NbaS and geosciences, (v) Actors: mobilization, consultation and acceptance, (vi) Regulatory and normative framework, (vii) Methods and tools, (viii) Implementation of a NbaS.Each course contains a general part gathering basic knowledge, and a second more specific part called in-depth.The latter makes it possible to adapt to the environment highlighted by the training in which the module is provided (urban, agricultural, humid, maritime and coastal, mountainous, natural, forest, or all environments).This structuring allows the module to be flexible and adaptable to the level and field of application of the targeted training.

Intensive agricultural practices increase agrochemical pollution, particularly nitrogen (N) based fertilizers, which present an environmental risk. This study aims to evaluate long-term (2009– 2020) data on soil water regime and nitrate dynamics at an agricultural experimental site on fine-textured soils and to better understand the implications of N management in relation to groundwater pollution. The field site is located in the Biđ field (eastern Croatia), in the proximity of the Sava river. Zero-tension lysimeters were installed at six selected locations. Lysimeters were used to monitor the water regime, i.e., outflows in which nitrate concentration was measured, while additional soil- water samples were collected via 4 and 15-meter- deep monitoring wells. Soil hydraulic parameters were estimated by combining the laboratory measurements, and estimation in RETC software. Water regime and nitrate leaching in lysimeters were simulated using HYDRUS-1D for each year to allow crop rotation and to evaluate their effects individually. The HYDRUS-1D model successfully reproduced lysimeter outflows and nitrate dynamics, which was confirmed with high R2 values (water: 93% above 0.7, and nitrate: 73% above 0.7) indicating the good performance of the model simulating nitrification chain reactions. Principal component analysis (PCA) was performed to identify the relationships among all soil properties and environmental characteristics. The results showed the complex interaction of soil hydraulic properties, precipitation patterns, plant uptake, and N application. All locations have a decreasing trend of nitrate leaching over the investigation period. Most of the lysimeter outflows and elevated nitrate concentrations were connected to the wet period of the year when the soil was saturated, and evapotranspiration was low. The results of this study show that it is important to optimize N fertilizer applications for each particular environmental condition to reduce nitrate loss. The study indicates the importance of long-term field studies, key for agro-hydrological modeling and the improvement of agricultural practices.

International audience

Hydrological applications such as storm-water management or flood design usually deal with and are driven by region-specific reference rainfall regulations or guidelines based on Intensity-Duration-Frequency (IDF) curves. IDF curves are usually obtained via frequency analysis of rainfall data using which the exceedance probability of rain intensity for different durations are determined. It is also rather common for reference rainfall to be expressed in terms of precipitation P, accumulated in a duration D (related to rainfall intensity ), with a return period T (inverse of exceedance probability). Meteorological modules of hydro-meteorological models used for the aforementioned applications therefore need to be capable of simulating such reference rainfall scenarios. The multifractal cascade framework, since it incorporates physically realistic properties of rainfall processes (non-homogeneity or intermittency, scale invariance and extremal statistics) seems to suit this purpose. Here we propose a discrete-in-scale universal multifractal (UM) cascade based approach. Daily, Hourly and six-minute rainfall time series datasets (with lengths ranging from 100 to 15 years) over three regions (Paris, Nantes, and Aix-en-Provence) in France that are characterized by different climates are analyzed to identify scaling regimes and estimate corresponding UM parameters (α, C1) required by the UM cascade model. Suitable renormalization constants that correspond to the P, D, T values of reference rainfall are used to simulate an ensemble of reference rainfall scenarios, and the simulations are finally compared with datasets. Although only purely temporal simulations are considered here, this approach could possibly be generalized to higher spatial dimensions as well.

Intercropping with legumes has attracted much attention worldwide, regarded as a sustainable alternative to chemical N-fertilizer. Many studies have investigated the effects of introducing legumes into sugarcane systems. However, how agro-environmental conditions influence the effect of legumes on sugarcane yield is still unclear. Thus, we performed a meta-analysis to (i) quantify the effect of legume intercropping on sugarcane yield, (ii) assess how agro-environmental and management conditions influence the response of sugarcane yield to intercropping, and (iii) assess the influence of legumes in interaction with weeds on sugarcane yield. We combined data from a systematic literature review and experimental data from a network of experiments conducted on the tropical island of La Réunion. 315 observations (one-year x site x intercropping treatment) were analyzed with mixed effects models to assess the effect of legume intercropping on sugarcane yield and factors influencing the response of sugarcane yield. Intercropping with legumes resulted in a 3.34 % lower sugarcane yield on average compared to the monoculture treatment, but with high variation from − 65 to + 47 %. Our study highlighted how the competition of legumes on sugarcane yield is reduced by higher annual temperatures and soil organic carbon. Late sowing and early destruction date of the legume mitigated the negative effect of legumes on sugarcane yield. Our study also showed that the negative impact of legumes on sugarcane yield increased over years of intercropping. Further studies are needed to better synchronize legume sowing and destruction dates while reducing trade-offs between expected services (N enrichment and weed control) and disservices (yield loss, costs, and labor time) in sugarcane agrosystems according to the climate and soil context.

During the last few decades, the urban hydrological cycle has been strongly modified by the built environment, resulting in fast runoff and increasing the risk of waterlogging. Nature-based solutions (NBSs), which apply green infrastructures, have been more and more widely considered as a sustainable approach for urban storm water management. However, the assessment of NBS performance still requires further modelling development because of hydrological modelling results strongly depend on the representation of the multiscale space variability of both the rainfall and the NBS distributions. Indeed, we initially argue this issue with the help of the multifractal intersection theorem. To illustrate the importance of this question, the spatial heterogeneous distributions of two series of NBS scenarios (porous pavement, rain garden, green roof, and combined) are quantified with the help of their fractal dimension. We point out the consequences of their estimates. Then, a fully distributed and physically based hydrological model (Multi-Hydro) was applied to consider the studied catchment and these NBS scenarios with a spatial resolution of 10 m. A total of two approaches for processing the rainfall data were considered for three rainfall events, namely gridded and catchment averaged. These simulations show that the impact of the spatial variability in rainfall on the uncertainty of peak flow of NBS scenarios ranges from about 8 % to 18 %, which is more significant than those of the total runoff volume. In addition, the spatial variability in the rainfall intensity at the largest rainfall peak responds almost linearly to the uncertainty of the peak flow of NBS scenarios. However, the hydrological responses of NBS scenarios are less affected by the spatial distribution of NBSs. Finally, the intersection of the spatial variability in rainfall and the spatial arrangement of NBSs produces a somewhat significant effect on the peak flow of green roof scenarios and the total runoff volume of combined scenarios.

Inflammation is a complex physiological process triggered in response to harmful stimuli. It involves specialized cells of the immune system able to clear sources of cell injury and damaged tissues to promote repair. Excessive inflammation can occur as a result of infections and is a hallmark of several diseases. The molecular basis underlying inflammatory responses are not fully understood. Here, we show that the cell surface marker CD44, which characterizes activated immune cells, acts as a metal transporter that promotes copper uptake. We identified a chemically reactive pool of copper(II) in mitochondria of inflammatory macrophages that catalyzes NAD(H) redox cycling by activating hydrogen peroxide. Maintenance of NAD+ enables metabolic and epigenetic programming towards the inflammatory state. Targeting mitochondrial copper(II) with a rationally-designed dimer of metformin triggers distinct metabolic and epigenetic states that oppose macrophage activation. This drug reduces inflammation in mouse models of bacterial and viral (SARS-CoV-2) infections, improves well-being and increases survival. Identifying mechanisms that regulate the plasticity of immune cells provides the means to develop next-generation medicine. Our work illuminates the central role of copper as a regulator of cell plasticity and unveils a new therapeutic strategy based on metabolic reprogramming and the control of epigenetic cell states.

The hydrological behavior of granular substrates is of critical interest in Nature-Based Solutions (NBS) like green roofs. To simulate this behavior in a physically realistic manner it is indispensable to model the substrate’s Hydraulic Conductivity (HC) as it determines infiltration rate at various degrees of saturation. Since HC is directly dependent on water content retained by the substrate, it is necessary to physically model this Water Retention (WR) behavior too. Capillary water is stored or retained in pore spaces and this water content that can be retained by a substrate under different suction pressures is therefore dependent upon its Pore Size Distribution (PSD). Since pores in any granular media are spaces where grains are absent, their size distribution too is intrinsically related to the substrate’s Grain Size Distribution (GSD) which provides the probability of finding grains smaller than some diameter dgs. Although some earlier studies have attempted to model PSD, WR, and HC, they frequently use simplifying mono-fractal (fractal) approximations, whereas this study proposes a more generalized multifractal-based approach. Furthermore, while it is quite usual to incorporate pore tortuosity through some indirect parameter l in the HC model, a related ink-bottle effect which even though capable of affecting WR behavior is commonly ignored. Therefore this study suggests the use of a new parameter i in the WR model to physically represent this ink-bottle effect (a consequence of the substrate’s pore configuration or arrangement) which additionally takes into account the pore tortuosity without using l. The proposed models are validated using experimental measurements from 4 different commercially used green roof substrates.Keywords: Multifractals, Non-linear geophysical systems, Cascade dynamics, Scaling, Hydrology, Green roof substrates.

With the advances of the Nature-Based Solutions (NBS) concept, much attention is being given to its potential for climate change adaptation. Accordingly, Nature-Based adaptation Solutions (NBaS) have become central elements for action on climate. In the EU, the Horizon 2020 (H2020) program translates the ambition of positioning Europe as the world’s leader in NBS. In an effort to draw a comprehensive roadmap of these efforts, this study investigates 21 H2020 projects that utilize NBaS throughout different ecosystems. The main objectives of this study are to provide an inventory of current knowledge, to extract identified risks and knowledge limitations, and to propose future research orientations.For this purpose, the CORDIS database was used to identify the relevant projects. Using the keyword nature-based solutions and through a rigorous search of research topics and programs, the following projects were retained (based on the existence of deliverables at the time of this study): CLEARING HOUSE, CLEVER Cities, Connecting Nature, DRYvER, EdiCitNet, EuPOLIS, FutureMARES, GrowGreen, NAIAD, Nature4Cities, NATURVATION, OPERADNUM, PHUSICOS, proGIreg, RECONECT, REGREEN, RENATURE, ThinkNature, UNaLab, Urban GreenUP and URBiNAT. Consequently, 137 deliverables were individually examined. Numerous findings were then obtained. These were divided into general and specific results.In terms of general results, the definition of the NBS concept is still debated: some projects adopt the EC’s definition, others compare between the EC’s and the IUCN’s definition, while many reformulate their own. Second, the continental geographical gradient of pilot sites follows a dense South-West orientation in contrast to a less developed North-Eastern line. In terms of target ecosystems, 61% of the projects target the urban realm, while freshwater ecosystems come second. The coastal, natural and mountainous environments are the least addressed. The focus on urban systems makes most of the generated knowledge, designed solutions and monitoring methods more or less restricted to this realm, hence not necessarily applicable in other settings. Regarding climatic challenges, urban heat islands and floods came first. These are followed by sea level rise, intense precipitation, heat stress, storms, erosion and landslides.In terms of specific findings, current knowledge and limitations were grouped in-depth per ecosystem (urban, freshwater, marine-coastal, mountainous, forest-natural, and agricultural) and per main research topics (climate change adaptation, risks of oversimplification, system complexity, uncertainty, the scale quandary, progress measuring-monitoring, and disservices). On this basis, several research perspectives were then proposed. Accordingly, interest in NBS-NBaS should extend beyond the urban ecosystem, while deeper knowledge on nature (the physical fundamentals of the N) in NBS-NBaS is needed. It is also important to understand if NBaS are intended to withstand weather change and/or climate change. For the implementation of wide-scale solutions, an extension beyond conservationism is needed, and a better accommodation of uncertainties is required. Therefore, understanding ecosystem tipping points, thresholds, and the resource efficiency of NBaS is primordial. Finally, it is crucial to acknowledge that both ecosystem development and climate change will keep progressing throughout the existence of NBaS. Therefore, the interacting co-evolution of ecosystems, NBaS and climate change should be further studied where their interaction could be forgotten.

Nature-based Solutions are presented as relevant features to make the cities more resilient in a context of global change. By providing ecosystem services, they are considered as particularly efficient solutions to mitigate urban heat islands and floods, while preserving biodiversity. Nevertheless, despite this consensus, it is still very difficult to quantitatively assess these services. Some methodologies and tools have therefore to be developed to better understand the thermo-hydric behavior of such infrastructure in relation with biodiversity, and to assess their performances across scales.This presentation aims to present the work carried out to solve these issues through two current projects dedicated to NBS. On the one hand, the French ANR EVNATURB project aims to develop an operational platform to assess some of the eco-system services (ie stormwater management, cooling effect, or biodiversity conservation) provided by NBS at the district scale. On the other hand, the LIFE ARTISAN project deals with the creation of a framework to promote NBS for the implementation of the national plan for adaptation to climate change (PNACC) in France by improving scientific and technical knowledge. Both aim to develop and disseminate relevant tools for project leaders (for the design, sizing, implementation and evaluation of ecosystem performance).The presentation of the results is particularly focused on monitored pilot sites and modelling platforms developed during these projects. In addition to these scientific investigations devoted to the thermo-hydric balance, some specific literature reviews and interviews were conducted to facilitate the choice of the more efficient species to implement, and the way to arrange NBS to optimize their performances. One of the results of this work is a dedicated database related to the a priori main ecosystem functions provided by plant species, and a list of quantitative indicators relevant for an urban project (certification, labelling, compliance with local regulations, ...) and that NBS can comply. Then this presentation concludes on remaining research gaps that have be to filled on this topic.

Green roofs are widely recognized as a Nature-Based Solution that regulates the air temperature within urban environments. Thanks to the shading effect and the evapotranspiration process (ET), the temperature decreases in the green roof surrounding area. Hence, the implementation of green roofs in urban environment for this purpose requires the quantification of ET-related processes at different scales. Nevertheless, because of complexity of the ET process, different methods of measurement have been used at different scales. However, no agreement about the way to assess ET rates over green roofs has been reached between the scientific community, as well as its behaviour at different urban scales is still unclear. Therefore, more investigations on ET measurements are required for better understand and analyse its spatial and temporal variability at different scales.For this purpose, a Larger Aperture Scintillometer (LAS) MKI from Kipp&Zonen was installed over a wavy-green roof of 1 ha, the Blue Green Wave (BGW), located in the Ecole des Points ParisTech (France). The main objective of this set-up was to assess the refractive index-structure parameter (Cn2) fluctuations from which ET can be deduced by means of the Monin-Obukhov similarity theory and the surface energy balance. As LAS is mainly influenced by fluctuations of air temperature, a radiometer equipped with a temperature sensor was installed in addition over the BGW. Then, the scaling statistics of Cn2 and temperature were studied through their power spectral density and their structure function.The results obtained from the power spectral density demonstrated the scaling invariance of Cn2 and temperature over certain ranges of scales. The spectral exponents are close to 5/3 for Cn2 and to 2 for the temperature. Regarding the scaling exponents of the structure functions, the multifractal feature of the structure parameter Cn2 and the temperature was confirmed. The scale-invariant properties of the empirical data were characterised using the Universal Multifractal framework.

International audience; N biogeochemical flows and associated N losses exceed currently planetary boundaries and represent a major threat for sustainability. Measuring N losses is a resource-intensive endeavour, and not suitable for ex-ante assessments, thus modelling is a common approach for estimating N losses associated with agricultural scenarios (systems, practices, situations). The aim of this study is to review some of the N models commonly used for estimating direct field emissions of agricultural systems, and to assess their suitability to agricultural systems featuring organo-mineral or organic fertilisation, non-arable crops, or happening under tropical and subtropical conditions. Simple N models were chosen based on their frequent use in LCA, following a literature review, including ecoinvent v3, Indigo-N v1/v2, AGRIBALYSE v1.2/v1.3, and the Mineral fertiliser equivalents (MFE) calculator. Model sets were contrasted, among them and with the dynamic crop model STICS, regarding their consideration of the biophysical processes determining N losses to the environment from agriculture, namely plant uptake, nitrification, denitrification, NH 3 volatilisation, NO 3 leaching, erosion and runoff , and N 2 O emission to air; using four reference agricultural datasets. Models' consideration of management drivers such as crop rotations and the allocation of fertilisers and emissions among crops in a crop rotation, overfertilisation and fertilisation technique, were also contrasted, as well as their management of the mineralisation of soil organic matter and organic fertilisers, and of drainage regimes. We highlighted the reasons for the differing model outputs. Among these models, Indigo-N is the most data intensive, and ecoinvent the least. For the four agricultural datasets, the ecoinvent model predicted significantly lower values for NH 3 than the AGRIBALYSE and the STICS models. For N 2 O, no significant differences were found among models. For NO 3 , the ecoinvent and AGRIBALYSE models predicted significantly higher emissions than the STICS model, regardless of the fertilisation regime. For both emissions, values of Indigo-N were close to those of the STICS model. By analysing the reasons for such differences, and the underlying factors considered by models, a list of recommendations was produced regarding more accurate ways to model N losses (by including, for instance, the main drivers regulating emissions).

Most of the world's sugar is produced from a semi-perennial plant whose root system, although being one key to its success, remains poorly understood. In this study, we sought to describe how nitrogen fertilisation is likely to affect the development of the sugarcane root system and can have significant agronomic implications. We studied sugarcane root distribution, root biomass production and root N accumulation from soil cores sampled down to a depth of 1 m throughout the growth cycle of a ratoon crop in a 144 kgN ha−1 year fertilised plot and at crop harvest in six ratoon plots with fertilisation ranging from 0 to 330 kgN ha−1 year. The development of the root system in the fertilised sugarcane plot showed 1/homogeneous colonization of the topsoil by fine roots from the early phase, followed by 2/a progressive development of thicker roots mainly localised under the sugarcane row. The results suggested that nitrogen fertilisation could reduce root density in the topsoil layer. The root-to-shoot ratio of biomass and N mass decreased, respectively, from 2.1 to 0.3 and from 1.2 to 0.7 throughout an annual crop growth cycle in a fertilised plot. When sugarcane was not fertilised, an increase of 70% root biomass was observed as compared to fertilised sugarcane. In addition, approximately half of the cane N mass was found in the root compartment of the non-fertilised crop. The root system of sugarcane appeared to be a major pool of N that should be considered in studies dealing with fertiliser N use efficiency and N cycling in sugarcane agroecosystems.

Aims: The improvement of nitrogen use efficiency (NUE) of crops allows crop nitrogen (N) demands to be met while reducing N supply, and so reducing excess N which has potential negative environmental implications. NUE is often determined destructively at the end of crop growth-cycles without considering temporal variability. Here we present a methodological study which optimises the determination of NUE throughout the sugarcane growth-cycle using minimally destructive methods, and suggest the use of these methods for non-destructive NUE determination over the growth-cycle of other giant C4 crops. Methods and results: The determination of the NUE relied on the optimisation of three methods: the estimation of aboveground biomass, N content and N derived from fertiliser (NdfF). First, the ability of different allometric relationships to estimate sugarcane biomass was investigated by selecting a relationship based on height and diameter to estimate aboveground biomass along the crop growth-cycle. Secondly, we assessed the minimum number of harvested sugarcane required to construct a dilution curve to predict N content from biomass and found that a sampling of 5 sugarcane at 3 dates was sufficient to represent aboveground N content over the growth-cycle. Finally, the ability of 15N content of individual leaves to represent the NdfF in 15N-fertilised cane was tested. The first and second leaf below the top visible dewlap were the most representative. Based on a variance analysis, we assessed the level of influence of each method on the NUE calculation. Crop age accounted for 54% of the variance of NUE, the choice of 15N leaf 13%, with the choice of model to estimate biomass and the number of plants harvested for the N dilution curve, each accounting for less than 2% over the four sampling dates. Conclusions: This study highlighted the importance of evaluating NUE not only at the point of harvest. We propose, therefore, a set of methods to study NUE throughout the sugarcane growth-cycle by using minimally destructive sampling.

Previous works related to the application of the multifractal theory for analyzing the grain size distribution (GSD), showed the potential of this approach to deal with this complex issue. However, absence of the practical application of this kind of statistical analysis raised some doubts among the soil scientists. Compared to the experimental dry sieving method, which is based on mass representations of different grain sizes, the approach presented in this work relies on the analysis of grain densities (density indicators) scanned by means of X-ray CT (Computed Tomography). By reducing the resolution of the scanned soil image(s), the cumulative representation of solid particles equal to or larger than the actual discretization element can be determined, and described analytically by means of the universal multifractals (UM). For validation of the new UM approach, the X-ray CT results of three different soils were used: the volcanic substrate covering Green Wave (a green roof of Champs-sur-Marne in France), and two horizons of the soil collected from the low land mountain area of Sierra de Guadarrama in Spain. Comparison between the proposed UM model and the experimental data of these three materials confirms that the GSD can be reasonably well predicted from the scanned images of soils covering wide range of grain sizes. The UM model, unlike the fractal-based models, accounts for fractal dimension that depends on grain size, and hence, based on the preliminary results presented in this work, it could be rather useful in case of multi-modal soils whose GSD curves are described with multiple fractal dimensions.

A wider recognition of climate change enhances in the society the 3R approach – Reduce, Recycle and Reuse –, thus broadening the spectrum of Urban Geoscience topics. This strengthens also the consensus that business models of companies are often too focused on their financial value, to the detriment of social and environmental added value. It therefore seems timely to change this way of doing things so that their growth is built more as part of a sustainable development approach, by emphasising the paradigm shift of ‘shared value’.'Shared value' means that by meeting the needs and challenges of society, businesses can create their economic value in a way that also benefits society, in direct link with COP21's commitments and in response to energy, environmental and IT transition laws, hence bringing political ambition and market reality together. To highlight such opportunities, this presentation will capitalise on several research initiatives launched in Greater Paris during recent years related to this topic (https://hmco.enpc.fr/portfolio-archive/):(i) research to extend non-linear approaches in environment and geophysics;(ii) results on defining environmental indicators for our cities - considering their multimodal, multiscale and multifunctional structure - to quantify their environmental impacts (e.g., thermal, visual comfort, air quality, heat island mitigation, stormwater management etc.);(iii) numerous instrumentation and modelling experiments related to the impacts of climate change and to the means of their attenuation;(iv) results on the monetisation of amenities provided by Blue-Green Solutions in urban areas and their large-scale socio-economic contextualisation;(v) environmental assessment of many (infra)structures that take into account their design method, implementation, operation, maintenance and end-of-life.All these research initiatives constitute the basis for the ‘shared value’ theoretical emergence in the 4C framework – Cognitive, Collaborative, Coevolutionary and Complex – systems, with a practical methodology towards the sustainable, desirable and resilient city and call for larger developments of Urban Geosciences.

Nature-based solutions appear to be an interesting option for enhancing the thermal comfort of the urban population during summer, while providing multiple services (e.g. biodiversity enhancement, the reduction in buildings energy consumption, stormwater management, acoustic insulation or air purification). However, the effects of green infrastructures on thermal comfort are not properly characterized, which prevents urban planning policies to be consistent.The impacts of a single idealized tree on its microclimate are studied. The sensible heat flux emitted by the soil to the air is computed by solving the heat equation in a semi-infinite domain with a Robin boundary condition representing the energy balance of the soil. The sensible heat flux emitted by the vegetation is computed in two ways: with Newton’s law and with an energy-balance approach. This model is applicated to a tree-shaped structure supporting climbing plants and compared with the experimental data collected. The prototype has been built to assess the cooling performance of this type of vegetation, and particularly the part played by soil shading, evapotranspiration (i.e. the latent heat flux emitted to the air by the plants and the soil) and absorbed solar radiation. These results may permit to estimate the contribution of vegetation for mitigating urban heat island effects on a larger scale.

Hydrological applications such as flood design usually deal with and are driven by region-specific reference rainfall regulations, generally expressed as Intensity-Duration-Frequency (IDF) values. The meteorological module of hydro-meteorological models used in such applications should therefore be capable of simulating these reference rainfall scenarios. The multifractal cascade framework, since it incorporates physically realistic properties of rainfall processes such as non-homogeneity (intermittency), scale invariance, and extremal statistics, seems to be an appropriate choice for this purpose. Here we suggest a rather simple discrete-in-scale multifractal cascade based approach. Hourly rainfall time-series datasets (with lengths ranging from around 28 to 35 years) over six cities (Paris, Marseille, Strasbourg, Nantes, Lyon, and Lille) in France that are characterized by different climates and a six-minute rainfall time series dataset (with a length of around 15 years) over Paris were analyzed via spectral analysis and Trace Moment analysis to understand the scaling range over which the universal multifractal theory can be considered valid. Then the Double Trace Moment analysis was performed to estimate the universal multifractal parameters α,C1 that are required by the multifractal cascade model for simulating rainfall. A renormalization technique that estimates suitable renormalization constants based on the IDF values of reference rainfall is used to simulate the reference rainfall scenarios. Although only purely temporal simulations are considered here, this approach could possibly be generalized to higher spatial dimensions as well.KeywordsMultifractals, Non-linear geophysical systems, Cascade dynamics, Scaling, Hydrology, Stochastic rainfall simulations.

The challenges imposed by climate change and urbanization require a paradigm yet holistic shift that considers the trade-off between ecosystemic conservation, social needs and economic growth. By concomitantly providing socioeconomic and environmental benefits, Nature Based Solutions (NBS) according to the European Commission (EC) present viable, resource-efficient and adaptable tools for ensuring the above-mentioned transition. Accordingly, NBS are high on European and French priority agendas, and are believed to be the way forward. The abundant scientific literature on NBS solidifies their potential through the various advantages they present. Evidently, NBS are win-win resolutions to environmental challenges (climate change, natural risks, food and water security), they support greener economies, conserve biodiversity, promote sustainability, support adaptive capacities, and reduce natural/socioeconomic sensitivities. In spite of their potential, NBS are faced by many obstacles. Conceptual obstacles include contested definitions of NBS, reduced reporting on uncertainties, and overlaps with sister notions that make the NBS concept somewhat vague. Systemic challenges include governance barriers, public willingness to adopt NBS and stakeholder participation (acceptance, perspectives and engagement). Implementation challenges encompass limited funds or budgets, difficulties of upscaling what works and maintaining-monitoring progress. Accounting for the above-mentioned elements, this study will use France as a micro scale and the European continent as a macro scale, to provide a local and regional inventory of NBS’ potential and limits. First, an in-depth bibliographic analysis and text mining techniques are carried out for providing detailed science-based evidence on the performance of NBS. For the national scale, peer-reviewed literature from the Scopus database and official UN bodies or international organizations reports are used. For the European scale, deliverables of several Horizon 2020 projects serve the purpose. Subsequently, an analysis of stakeholder profiles, categories, and participation for mapping NBS actors in both contexts will follow. By combining theoretical investigations and stakeholder analysis, a holistic representation of the NBS framework is ensured. The logic behind this approach is to draw up scientific and technical evidence on NBS to mainstream their integration into development projects. Accordingly, the objective of this research work falls under one of the several actions of the Life ARTISAN project, action A1: reporting on obstacles and levers for Nature Based Adaptation Solutions. Under this scope, the project ARTISAN standing for “Achieving Resiliency by Triggering Implementation of nature-based Solutions for climate Adaptation at a National scale” aims to achieve the plans set in France’s second national climate change adaptation plan by leveraging NBS. Beyond the national scale, by capitalizing on past experiences and grouping dispersed findings, this study will provide deeper insights on NBS, and will allow a prioritization of research and knowledge building needs.

Worldwide, research community has studied the benefits of green and blue spaces implementation in urban areas, generating a great amount of literature regarding this topic. Since these solutions are of interest to face climate change impacts in cities, the European Commission (EC) has funded several projects to make an extensive review of the available literature. Three of these projects were especially studied here, namely EKLIPSE, Mapping Assessment of Ecosystem and their Services- Urban Ecosystem (MAES: Urban Ecosystems), and NATure-based URban innoVATION (NATURVATION). They all aim to identify the physical and social impacts, benefits and trade-offs of Nature-Based Solutions (NbS).To objectively compare findings presented in the deliverable reports, a text-mining approach was carried out. This methodology coupled with a data visual representation allowed to convert the EC projects reports (corpus) into a meaningful structured analysis. As a result, a graphical representation was created, making possible to recognize concepts, patterns and attributes addressed by each text, as well as stakeholders and their position with respect to the topic. The text mining analysis was implemented through Gargantex Blue Jasmine Version (an open source software developed by ISC-PIF). Gargantex results permitted to recover a list of key-terms from each corpus based in their co-occurrence in the whole text. These terms were used to elaborate a visual representation or network, placing the words strongly related close to each other and characterizing the obtained clusters by a similar color.This approach underlined the specific focus of each project: the conciliation between urbanisation and urban ecosystems (MAES), or the economic valuation and monetisation of NbS (NATURVATION) for instance. Moreover, it demonstrated that despite the different literature review methodologies of each report/project, there are some common trends exhibited by the obtained graphical networks and their statistical attributes. For instance, the need to assess the NbS performance with some adapted indicators; and the important EC supporting role in the implementation of NbS. Similarly, some regulating (e.g. water quality or temperature reduction) and cultural (e.g. recreation or health benefits) services are more addressed. This analysis can be applied to all kind of corpus, which makes it easy to understand different and similar concepts and approaches of a set of text data. A text-mining analysis can be conducted over the direct references of NbS benefits, on a collection of publications of a research database like Scopus or Science Direct.

The need to adapt and increase the resilience of urban areas regarding the issues induced by urbanization and climate change effects (e.g. floods, Urban Heat Island, pandemics, etc.), has led to propose several strategies as the Natural-Based Solutions (NBS), which are focus on restoring natural processes such as infiltration and evapotranspiration (ET) in urban areas. In consequence, the increasing interest on NBS installation (highly supported by the H2020 program of the European Commission) by urban planners, decision-makers, researchers and the residing population has conducted to question the most efficient ways of NBS deployment. In this context, the urban dynamics (e.g. population density, land use patterns, transport network, etc.) and the distribution of green areas at different spatial scales play a key role that characterise the urban development in the territory.Based on the study of an urban agglomeration named Est-Ensemble, located at the east of Paris (France), this research aims to: i) determinate the fractal dimension of the built-up and green areas by using 2 different box-counting methods; ii) set the potential areas to install NBS, through the development of an iterative downscaling scheme over the built-up structure with the software Fractalopolis, and following a polycentric approach inspired on the urban form of Ile de France Region, and iii) assess the population access to the nearest green spaces and deficit of green spaces.Further, from local scale measurements of ET made close to Est-Ensemble agglomeration, the authors carried out a multifractal analysis of the ET data to better evaluate the observed scaling behaviour. This will be coupled with spatial approach developed above to evaluate the impact of temperature reduction of different land use scenarios. This research is partly supported by the French ANR EVNATURB project.

The urban ecosystem is a very challenging environment that faces many problems such as various pollutions, higher temperatures than its surroundings or flooding risks due to soil sealing. Nature-based solutions (NBS) seem to be good option to address these problems, while simultaneously offering benefits for facing climate change and the biodiversity crisis. Despite their potential, NBS can be threatened by various urban disturbance, namely: land use change, pollution, or invasive species. These disturbances can have multiple consequences on urban NBS, such as causing changes in plant characteristics/traits, altering the services they provide, and even make certain plant populations disappear, etc. In turn, these consequences may even jeopardize the solutions themselves, which then may no longer solve the problems they originally targeted. To avoid this, NBS should be eco-designed, i.e. designed in function of their environment. Their management should be adaptive and should also take into consideration the evolution of climatic and anthropogenic factors. The choice of species should not be left to chance or random: In this sense, is it better to plant native species for biodiversity conservation or exotic species that are more likely to resist global changes? Is it better to find resistant or ruderal species that have proven themselves in the face of certain disturbances? In any case, it would be good to diversify any NBS to have a better chance of survival in the face of global changes.

Ferroptosis is a dedicated mode of cell death involving iron, reactive oxygen species and lipid peroxidation. Involved in processes such as glutathione metabolism, lysosomal iron retention or interference with lipid metabolism, leading either to activation or inhibition of ferroptosis. Given the implications of ferroptosis in diseases such as cancer, aging, Alzheimer and infectious diseases, new molecular mechanisms underlying ferroptosis and small molecules regulators that target those mechanisms have prompted a great deal of interest. Here, we discuss the current scenario of small molecules modulating ferroptosis and critically assess what is known about their mechanisms of action.

Hydro-meteorological risks are increasing and this could be due to global changes. These risks are particularly important in the urban context where most human beings live. Indeed, the impervious surfaces present in cities increase the risk of flooding, for example. Nature-Based Solutions can help to reduce these risks by creating permeable soils or storing water while promoting biodiversity. In this context, it is essential to understand what hinders the development and sustainability of these Nature-based Solutions in the city and what could help to deploy them on a large scale. For this purpose, various professionals working on Nature-Based Solutions in the city in France, were interviewed between 2020 and 2021, both in the academic and operational sectors, or even at the interface between the two: researchers in ecology or hydrology, IUCN (International Union for Conservation of Nature) project manager, project managers at the Regional Biodiversity Agency, director and natural environment manager of a watershed union, agro-economists engineer among others. They were asked what are the barriers and potential opportunities for Nature-Based Solutions implementation and sustainability in city. By analysing their answers, it emerges that the obstacles are more often cultural, political or financial than technical. The potential levers often mentioned are education and awareness-raising at all levels, especially for elected officials and the general public. Regulations such as the PLU (Local Urban Plan) and new funding for more natural spaces in the city also seem to be means of promoting Nature-based Solutions in urban areas. These interviews with diverse professionals directly involved in Nature-Based Solutions in cities allow to give real courses of action to be taken to democratize these Solutions throughout the French territory, or even internationally, and therefore ultimately reduce the risks of hydro-meteorology. This is one of the objectives of the French ANR project EVNATURB (Assessment of ecosystem performance of a renaturation of the urban environment), in which this study has been carried out.

Nature-Based Solutions (NBS) appear as some relevant alternatives to mitigate the consequences of climate change. For this reason, they are promoted for the implementation of the national plan for adaptation to climate change (PNACC) in France, in line with the Paris Agreement, the strategy of the European Union for adaptation to climate change and the French national strategy for biodiversity.Nevertheless, this ambitious goal of democratizing NBS poses some institutional and technical challenges because many obstacles remain to their implementation. Overcoming these shortcomings is the objective of the LIFE integrated project called ARTISAN (Achieving Resiliency by Triggering Implementation of nature-based Solutions for climate Adaptation at a National scale). Coordinated by the French Biodiversity Office (OFB), its consortium regroups several local authorities, technical, research and education institutes.For this purpose, ARTISAN is creating a framework promoting the implementation of NBS by improving scientific and technical knowledge about them, then by developing and disseminating relevant tools for project leaders (for the design, sizing, implementation and evaluation of ecosystem performance).To demonstrate that NBS can respond to a diversity of climatic, ecological and institutional contexts, 10 pilot sites will be monitored in metropolitan and overseas France. The concerned issues are for example the reduction of urban heat island by the de-waterproofing of the public space, the limitation of the impact of cyclonic episodes on the urbanized coastline overseas by promoting the restoration of the mangrove, and the decrease of agricultural water stress during the low flow period by the hydromorphological restoration of wetlands. These pilot sites will serve to develop, improve and validate operational tools, methods and trainings devoted to practitioners.

The growth of the world’s population living in urban areas has led to change from natural to highly dense and impermeable landscapes. Moreover, the intensity and frequency increase of extreme event...

The increasing incidence and intensity of extreme climate events are a major threat to global crop production. Sugarcane represents the main source of sugar and ethanol in tropical and sub-tropical regions. Here, we assessed the impacts of climatic variability and extreme events on sugarcane yield gaps in Reunion Island which is characterised by extreme spatial contrasts in climate, and is regularly subjected to cyclones or drought. We combined a process-based crop model with spatial databases of soil, climate and management data, to predict the annual sugarcane yield in each field over the whole island from 1998 to 2018. Simulated yields were compared to actual sugarcane yields from sugar producers in five agro-climatic zones. Extreme climate indices were calculated for extreme daily rainfall, temperature and drought, and their influence on yield gap was assessed using a Principal Component Analysis (PCA). The average total yield gap (YGT, i.e. the difference between potential sugarcane yield and actual yield, Mg ha-1) over Reunion Island was 96 Mg ha-1, explained by 34% throw crop management and hazards. YG due to crop management reached 65 Mg ha-1 with increasing rainfall and nitrogen mineralization rate and up to 88 Mg ha-1 with increasing temperature and radiation. Yield gap was correlated with the first axis of the PCA, highlighting how extreme rainfall induced increase in YGT. The actual yield loss was defined as the difference between the actual yield from sugarcane producers in a given year and the highest yield obtained during the whole studied period in the same zone. The annual actual yield loss increased by 0.6 Mg ha-1 per rainfall days higher than 29 mm d-1 along the annual crop cycle. Using this approximation, average actual yield loss due to heavy rain was estimated as 5.5 Mg ha-1 but it was higher than 10 Mg ha-1 for 25% of years in the East coast region. Our results highlight the need for improving sugarcane crop yield response to extreme rain in process-based crop models, in order to better assess climate change impacts in future.

Ferroptosis is a dedicated mode of cell death involving iron, reactive oxygen species and lipid peroxidation. Involved in processes such as glutathione metabolism, lysosomal iron retention or interference with lipid metabolism, leading either to activation or inhibition of ferroptosis. Given the implications of ferroptosis in diseases such as cancer, aging, Alzheimer and infectious diseases, new molecular mechanisms underlying ferroptosis and small molecules regulators that target those mechanisms have prompted a great deal of interest. Here, we discuss the current scenario of small molecules modulating ferroptosis and critically assess what is known about their mechanisms of action.

International audience; Can stable isotopes quantify soil carbon build-up from organic fertilizers? Application of organic fertilizers (OF) can supply carbon (C) to the soil in crop fields. OF-derived C (OF-C) is often estimated using the differential method that can be biased due to indirect effects of OF on soil C. This study tested three methods to quantify OF-C: (i) the widespread differential method, (ii) the synchronic isotopic method comparing plots with and without OF and (iii) the asynchronic isotopic method mimicking a trial without a control plot. These methods were implemented on an Arenosol and an Andosol supplied during 13 years with slurry or compost. The results highlighted the relevance of using the isotopic synchronic method, which focuses on the direct effect of OFs on the soil organic matter (without bias of vegetation change) and considers control soil's evolution. Considering limit of resolution in the Arenosol, the method was suitable after 4 years of fertilisation for an initial δ 13 C difference of 7.5 ‰ between OF and soil, and after 9 years for a difference of 3.5 ‰. A sensitivity analysis showed that particular attention must be paid to OF-δ 13 C variability to guarantee the method validity. The method proved to be suitable to study the factors controlling the OF-C fate in tropical soils.

International audience; To describe the water retention and transfer properties of an unsaturated soil over the whole range of matric suction, it is necessary to account for both capillary and adsorption phenomena. Existing models combine well‐known empirical functions for capillary water at lower suctions and more physically based ones for adsorptive water at higher suctions. To determine their full set of parameters, they however require different optimization procedures, among which those coming from capillary models are empirical. In this context, the main objective of this work is to develop a simple and robust physically based model of the water retention and transfer properties of unsaturated soils valid from saturation to oven dryness. To do so, new capillary‐based water retention and hydraulic conductivity functions founded on the fractal approach have been derived from the pore size distribution, by means of the Young‐Laplace law and Mualem's model. To describe adsorption phenomena, these functions are combined with those used in the Peters‐Iden‐Durner (PID) model, providing a model along the full range of suctions, with less parameters than the existing models. Our work also shows that some parameters are directly determined from the experimental grain size distribution data (the fractal dimension), or from the water retention data (air entry suction and residual water content), leaving only two parameters to be optimized. The model was successfully validated with respect to published experimental data from 10 different coarse, sandy, and clayey soils.

During the last decades, the urban hydrological cycle has been strongly modified by the built environment, resulting in fast runoff and increasing the risk of waterlogging. Nature-Based Solutions (NBS), which apply green infrastructures, have been more and more widely considered as a sustainable approach for urban stormwater management. However, the assessment of NBS performance still requires further modelling development because of their hydrological responses sensitively depends on the representation of multiscale space variability of both the rainfall and the NBS distribution. Indeed, we initially argue this issue with the help of the multifractal intersection theorem. To illustrate the importance of this question, the spatial heterogeneous distributions of two series of NBS scenarios (porous pavement, rain garden, green roof, and combined) are quantified with the help of their fractal dimension. We point out consequences of their estimates. Then, a fully-distributed and physically-based hydrological model (Multi-Hydro) was applied to consider the studied catchment and these NBS scenarios with a spatial resolution of 10 m under two different types of rainfall: distributed and uniform, and for three rainfall events. These simulations show that the impact of spatial variability of rainfall on the uncertainty of peak flow of NBS scenarios ranges from about 8 % to 17 %, which is more pronounced than those of the total runoff volume. In addition, the spatial variability of the rainfall intensity at the largest rainfall peak responds almost linearly to the uncertainty of the peak flow of NBS scenarios. However, the hydrological responses of NBS scenarios are less affected by the spatial distribution of NBS. Finally, the intersection effects of the spatial variability of rainfall and the spatial arrangement of NBS seem more pronounced for the peak flow of green roof scenarios and the total runoff volume of combined scenarios.

International audience; CD44 is a transmembrane glycoprotein linked to various biological processes reliant on epigenetic plasticity, which include development, inflammation, immune responses, wound healing and cancer progression. Although it is often referred to as a cell surface marker, the functional regulatory roles of CD44 remain elusive. Here we report the discovery that CD44 mediates the endocytosis of iron-bound hyaluronates in tumorigenic cell lines, primary cancer cells and tumours. This glycan-mediated iron endocytosis mechanism is enhanced during epithelial-mesenchymal transitions, in which iron operates as a metal catalyst to demethylate repressive histone marks that govern the expression of mesenchymal genes. CD44 itself is transcriptionally regulated by nuclear iron through a positive feedback loop, which is in contrast to the negative regulation of the transferrin receptor by excess iron. Finally, we show that epigenetic plasticity can be altered by interfering with iron homeostasis using small molecules. This study reveals an alternative iron-uptake mechanism that prevails in the mesenchymal state of cells, which illuminates a central role of iron as a rate-limiting regulator of epigenetic plasticity.

Salinomycin (1) exhibits a large spectrum of biological activities including the capacity to selectively eradicate cancer stem cells (CSC), making it and its derivatives promising candidates for the development of drug leads against CSC. It has been previously shown that salinomycin and its C20-propargylamine derivative (Ironomycin (2)) accumulate in lysosomes and sequester iron in this organelle. Herein, a library of salinomycin derivatives is reported, including products of C20-amination, C1-esterification, C9-oxidation, and C28-dehydration. The biological activity of these compounds is evaluated against transformed human mammary epithelial HMLER CD24low /CD44high cells, a well-established model of breast CSC, and HMLER CD24high /CD44low cells deprived of CSC properties. Unlike other structural alterations, derivative 4, which displays a cyclopropylamine at position C20, showed a strikingly low IC50 value of 23 nm against HMLER CD24low /CD44high cells. This study provides highly selective molecules to target the CSC niche, a potential interesting advance for drug development to prevent cancer resistance.

The challenges induced by the continuous urbanization and the climate change effects, such as extreme events (e.g. flooding or heat waves) or the intense increase of the urban temperatures (Urban Heat Island), encourage the implementation of Blue and Green Solutions (BGS). These solutions are inspired by the nature, favouring natural process in the cities like water infiltration or evapotranspiration (ET), reducing air temperature during heatwaves events.Characterize the thermal behavior governing a BGS is necessary to promote their implementation. Consequently, this research studies the energy fluxes –and particularly the evapotranspiration one- of a 1 ha wavy-shape green roof located in Champs-Sur-Marne (France), called Blue Green Wave (BGW). Therefore, a Large Aperture Scintillometer MKI, a CNR4 radiometer and 4 Type K thermocouples were installed on the BGW to measure the sensible heat flux of convection, the net radiation and the heat conduction into the soil substrate. The latent heat flux of ET was deduced from the energy balance.Each LAS unit was placed on the highest locations of the roof with about 100 m of distance between them. Diaphragms for short-range applications were placed in front of the units. The measurements were conducted on sunny and randomly days during the 2019 summer over an average time period of 7 hours.It appears that LAS sensible heat flux measurements on completely sunny days follow the net radiation flux trend. However, on cloudy days important flux fluctuations are noticed. Therefore, a sensitivity analysis was carried out to illustrate the significant correlation between the wind and the sensible heat flux during short time periods. In parallel, the heat conduction was analysed through a thermal gradient of temperature and a Fourier analysis demonstrating a poor conduction rate mainly on drier conditions of the BGW.Finally, the deduced latent heat was compared with the measurements of a dynamic evaporation chamber, confirming a significant over estimation of the latent heat computed from the energy balance. This can be explained by the sum of uncertainties related to each energy flux component, in addition to the restraint conditions of LAS measurement operation on the BGW (application over the limits of MOST theory). A multifractal analysis to determinate the temporal and spatial scaling behaviour of latent heat flux is ongoing.

Green roofs represent a market of several tens millions of m2 implemented every year in Europe. They appear to be particularly efficient to reduce the potential impact of new and existing urban developments by making the city “greener” and more resilient to climate change. Indeed, they provide several ecosystem services, particularly in stormwater management, urban heat island attenuation, and biodiversity conservation. For these reasons, municipalities are implementing specific policies to promote a large diffusion of green roofs on their territory. Nevertheless, to optimize their performances through urban scales, green roofs spatial distribution should be analysed.In order to study the current green roof implementation and to assess the relevancy of the related policies, a multi-scale analysis based on fractal theory as been conducted. Such analysis, widely used in geophysics, is particularly suitable to characterize spatial fields exhibiting strong heterogeneity over wide range of scales. This fractal analysis was performed here to characterize the spatial distribution of green roofs in several European cities (London, Amsterdam, Geneva, Lyon, Paris, Berlin, Frankfort, Copenhagen, Oslo…). These cities have been chosen because: (i) GIS database containing the location and geometry of implemented green roofs is available, (ii) they have implemented various kind of green roofs policies.The results show that every studied city depicts similar behaviour with the definition of three distinct scaling regimes. The second regime (between 16/32 and 512/1024 m) characterizes not only single roofs but their distribution in space which is what we are interested in. The fractal dimension charactering this regime is the most variable, ranging from 0.50 to 1.35 and illustrates some different degrees of progress in urban greening. It has to be noticed that the more ambitious incentive measures (where monetary subsidies are proposed) correspond to the cities characterized by the highest fractal dimension. Nevertheless, as these policies are relatively recent, they cannot completely explain the current green roof distribution (architectural history has also to be mentioned).The obtained results demonstrate some significant inconsistencies between political ambition and their in situ realization. They illustrate the necessity to better take into account the spatial distribution of green roof implementations in order to optimize their performances. To provide ecosystem services at large scales, green roofs have to be widely and relevantly implemented. Fractal analysis can be seen as innovative multi-scale approach to adjust policies for this purpose.This work has been made thanks to ANR EVNATURB project (https://hmco.enpc.fr/portfolio-archive/evnaturb/) and the Academic Chair “Hydrology for Resilient Cities”, a partnership between Ecole des Ponts ParisTech and the Veolia group.

International audience; To face the consequences of climate change and unsustainable urbanization, green roofs are currently widely implemented in urban environments. Despite their benefits to restore ecosystem services are quite well established at the roof scale, green roofs need to be widely and appropriately distributed to perform efficiently at larger scales. However for now, this scale-factor is not considered to guide and conduct green roof implementation policies. Here we show that a multi-scale analysis based on fractal theory is helpful in providing information for green roof implementation and in assessing the relevance of these policies. We found the fractal dimensions computed for green roofs are sparse, ranging from 0.49 to 1.35 for the nine studied cities, and illustrate some different degrees of progress in urban greening. Our results demonstrate some significant inconsistencies between political ambition and their in situ realization, and the necessity to better take into account the spatial distribution of green roof implementations in order to optimize their performances.

Cancer stem cells (CSC) constitute a cell subpopulation in solid tumors that is responsible for resistance to conventional chemotherapy, metastasis and cancer relapse. The natural product Salinomycin can selectively target this cell niche by directly interacting with lysosomal iron, taking advantage of upregulated iron homeostasis in CSC. Here, inhibitors of the divalent metal transporter 1 (DMT1) have been identified that selectively target CSC by blocking lysosomal iron translocation. This leads to lysosomal iron accumulation, production of reactive oxygen species and cell death with features of ferroptosis. DMT1 inhibitors selectively target CSC in primary cancer cells and circulating tumor cells, demonstrating the physiological relevance of this strategy. Taken together, this opens up opportunities to tackle unmet needs in anti-cancer therapy.

International audience; Gardner's (1956, https://doi.org/10.2136/sssaj1956.03615995002000030006x) transient method of measuring the hydraulic conductivity function of unsaturated media has been largely used, together with the improved graphical method proposed by Kunze and Kirkham (1962, https://doi.org/10.2136/sssaj1962.03615995002600050006x) to account for the impedance effect resulting from using a low hydraulic conductivity ceramic disk in porous plate testing. These methods are nowadays seldom used, since they have been replaced by numerical back analysis and methods for parameter optimization. Based on tests carried out on a specific device allowing to determine the water retention and transport properties of water in a coarse granular media at low suctions (up to 50 kPa), it was found necessary to account (i) for impedance effects and (ii) for the effects of nonconstant suction increments, as is often the case when using the hanging column technique. A new method is proposed to account for impedance effects, based on an analytical solution of the equations governing water transfer. The validity of this method is tested by considering experimental data from three distinct materials: a coarse green roof volcanic substrate, poorly graded sand, and undisturbed silty clay. Compared to the graphical method Kunze and Kirkham's method, it is less operator‐dependent and hence more objective. It is also simpler than numerical back analysis methods, since it does not require any use of numerical code or parameter optimization algorithm, providing a more direct and reliable access to the hydraulic conductivity. An analytical solution is also proposed to solve the problem resulting from the application of a nonconstant suction increment.