A review of the processes and effects of droughts and summer floods in rivers and threats due to climate change on current adaptive strategies

Europe is expected to experience a greater frequency of floods and droughts as precipitation and evapotranspiration patterns are modified by climate change in future. Several large scale drought and flooding events have occurred in Europe since 2000. Studies of drought are rare but indicate important impacts on freshwater habitats, water quality, plants and animals, which may have wider consequences for ecosystem functioning. The main factors determining the impacts of droughts and floods are event duration and seasonality of the event. A diverse habitat distribution and the presence of refugia at the reach scale confer the most resilience against droughts and floods. Management measures will also be impacted particularly with regard to riparian zones, channel morphology, flow and floodplain connectivity. However there is a conflict between management actions that target the effects of drought, and those that target floods. This report reviews information on droughts and aseasonal floods (summer floods) published since 2000 with a principal focus on small lowland rivers. Using several recent (post 2000) reviews on these topics, we describe abiotic and biotic effects of droughts and floods, providing recent European examples where possible. We explain the current status of droughts and summer floods in Europe, and where the main sources of data can be found. We highlight the threats posed by these phenomena to some of the most common current adaptive management strategies in place in the EU. To this end we use measures already described within REFRESH under Deliverables 1.1 and 1.2, and we focused solely on adaptive measures relating to riparian zones, channel morphology, flow and floodplain connectivity

Green-Kubo formula for weakly coupled system with dynamical noise

We study the Green-Kubo (GK) formula $\kappa (\varepsilon, \xi)$ for the heat conductivity of an infinite chain of $d$-dimensional finite systems (cells) coupled by a smooth nearest neighbour potential $\varepsilon V$. The uncoupled systems evolve according to Hamiltonian dynamics perturbed stochastically by an energy conserving noise of strength $\xi$. Noting that $\kappa (\varepsilon, \xi)$ exists and is finite whenever $\xi> 0$, we are interested in what happens when the strength of the noise $\xi \to 0$. For this, we start in this work by formally expanding $\kappa (\varepsilon, \xi)$ in a power series in $\varepsilon$, $\kappa (\varepsilon, \xi) = \varepsilon^2 \sum_{n\ge 2} \varepsilon^{n-2} \kappa_n (\xi)$ and investigating the (formal) equations satisfied by $\kappa_n (\xi$. We show in particular that $\kappa_2 (\xi)$ is well defined when no pinning potential is present, and coincides formally with the heat conductivity obtained in the weak coupling (van Hove) limit, where time is rescaled as $\varepsilon^{-2}t$, for the cases where the latter has been established \cite{LO, DL}. For one-dimensional systems, we investigate $\kappa_2 (\xi)$ as $\xi\to 0$ in three cases: the disordered harmonic chain, the rotor chain and a chain of strongly anharmonic oscillators. Moreover, we formally identify $\kappa_2 (\xi)$ with the conductivity obtained by having the chain between two reservoirs at temperature $T$ and $T+\delta T$, in the limit $\delta T\to 0$, $N \to \infty$, $\varepsilon \to 0$.Comment: New version with many improvement

Investigating river wetted habitat sensitivity to flow change

This project aimed to improve the understanding of the response of river wetted habitat (represented by wetted perimeter WP) to change in flow (Q) in order to support ecological status and potential assessment in UK rivers impacted by abstraction/flow regulation, which is of high relevance to dam and hydropower scheme design. The analysis relied on a pool of >1,000 UK sites with good quality hydraulic data. A method to assess objectively WP sensitivity to Q was developed, which models WP as a function of Q in a consistent manner, then identifies three different sensitivity zones and corresponding flow thresholds mathematically (ranging from high sensitivity occurring at lower flows, medium sensitivity, and low sensitivity at higher flows). The study then investigated if wetted habitat sensitivity patterns could be related to catchment/river reach types. For c. two thirds of sites, WP was found highly sensitive to flow change at Q95 (5th percentile) or below, suggesting generic environmental flow values can mask variations in hydraulic sensitivity; there was no site featuring low WP sensitivity below Q95. Regarding typology, statistically significant patterns between sensitivity thresholds/ slopes and river types based on key catchment descriptors (area, altitude, permeability) were found; WP tend to be more sensitive to Q at higher flows for sites associated with smaller, lower elevation, and/or lower permeability catchments; sites with larger, higher elevation, and/or lower permeability catchments may feature sharper differences between sensitivity zones

Mono- versus Multi-phosphonic Acid Based PEGylated Polymers for Functionalization and Stabilization of Metal (Ce, Fe, Ti, Al) Oxide Nanoparticles in Biological Media

International audienceFor applications in nanomedicine, particles need to be functionalized to prevent protein corona formation and/or aggregation. Most advanced strategies take advantage of functional polymers and assembly techniques. Nowadays there is an urgent need for coatings that are tailored according to a broad range of surfaces and that can be produced on a large scale. Herein, we synthesize mono-and multi-phosphonic acid based poly(ethylene glycol) (PEG) polymers with the objective of producing efficient coats for metal oxide nanoparticles. Cerium, iron, titanium and aluminum oxide nanoparticles of different morphologies (spheres, platelets, nanoclusters) and sizes ranging from 7 to 40 nm are studied in physiological and in protein rich cell culture media. It is found that the particles coated with mono-functionalized polymers exhibit a mitigated stability over time ( months). With the latter, PEG densities in the range 0.2-0.5 nm-2 and layer thickness about 10 nm provide excellent performances. The study suggests that the proposed coating allows controlling nanomaterial interfa-cial properties in biological environments

CONCEPTUAL DESIGN FOR ASSEMBLY IN AEROSPACE INDUSTRY: SENSITIVITY ANALYSIS OF MATHEMATICAL FRAMEWORK AND DESIGN PARAMETERS

AbstractOne of the most challenging activity in the engineering design process is the definition of a framework (model and parameters) for the characterization of specific processes such as installation and assembly. Aircraft system architectures are complex structures used to understand relation among elements (modules) inside an aircraft and its evaluation is one of the first activity since the conceptual design. The assessment of aircraft architectures, from the assembly perspective, requires parameter identification as well as the definition of the overall analysis framework (i.e., mathematical models, equations).The paper aims at the analysis of a mathematical framework (structure, equations and parameters) developed to assess the fit for assembly performances of aircraft system architectures by the mean of sensitivity analysis (One-Factor-At-Time method). The sensitivity analysis was performed on a complex engineering framework, i.e. the Conceptual Design for Assembly (CDfA) methodology, which is characterized by level, domains and attributes (parameters). A commercial aircraft cabin system was used as a case study to understand the use of different mathematical operators as well as the way to cluster attributes

Wasl is crucial to maintain microglial core activities during glioblastoma initiation stages

Microglia actively promotes the growth of high‐grade gliomas. Within the glioma microenvironment an amoeboid microglial morphology has been observed, however the underlying causes and the related impact on microglia functions and their tumor promoting activities is unclear. Using the advantages of the larval zebrafish model, we identified the underlying mechanism and show that microglial morphology and functions are already impaired during glioma initiation stages. The presence of pre‐neoplastic HRasV12 expressing cells induces an amoeboid morphology of microglia, increases microglial numbers and decreases their motility and phagocytic activity. RNA sequencing analysis revealed lower expression levels of the actin nucleation promoting factor wasla in microglia. Importantly, a microglia specific rescue of wasla expression restores microglial morphology and functions. This results in increased phagocytosis of pre‐neoplastic cells and slows down tumor progression. In conclusion, we identified a mechanism that de‐activates core microglial functions within the emerging glioma microenvironment. Restoration of this mechanism might provide a way to impair glioma growth