Search

Understanding how mangroves respond to sea level rise is critical for coastal management and conservation. This study investigates the feasibility of two remote sensing techniques, Light Detection and Ranging (LiDAR) and Structure-from-Motion (SfM) photogrammetry, to monitor changes in mud elevation that are critical to mangrove establishment dynamics. SfM photogrammetry can provide low-cost 3D modeling from imagery, while LiDAR provides high-precision elevation and vegetation data. Our analysis shows that SfM photogrammetry provides reasonably accurate surface elevation data with a root mean square error (RMSE) of 0.14 meters and a significant correlation coefficient (r = 0.74) compared to LiDAR measurements. This highlights the complementarity between the two, as the effectiveness of SfM photogrammetry is in the early stages of colonization, and then the need to use LiDAR with dense vegetation as the mangroves mature. This shows that a simple method of photogrammetry can remain effective until the vegetation reaches a certain threshold, and this can be particularly useful in the perspective of using mud elevation as a first low-cost diagnosis for potential mangrove rehabilitation project to assess the colonization suitability of mudflats.

When anticyclonic conditions persist over mountainous regions in winter, cold-air pools (i.e. thermal inversions) develop in valleys and persist from a few days to a few weeks. During these persistent cold-air pool (PCAP) episodes the atmosphere inside the valley is stable and vertical mixing is prevented, promoting the accumulation of pollutants close to the valley bottom and worsening air quality. The purpose of this paper is to address the impact of climate change on PCAPs until the end of this century for the alpine Grenoble valleys. The long-term projections produced with the general circulation model MPI (from the Max Planck Institute) downscaled over the Alps with the regional climate model MAR (Modèle Atmosphérique Régional) are used to perform a statistical study of PCAPs over the period 1981–2100. The trends of the main characteristics of PCAPs, namely their intensity, duration, and frequency, are investigated for two future scenarios, SSP2–4.5 and SSP5–8.5. We find that the intensity of PCAPs displays a statistically significant decreasing trend for the SSP5–8.5 scenario only. This decay is explained by the fact that air temperature over the century increases more at 2 m above the valley bottom than in the free air at mid-altitudes in the valley; this might be due to the increase of specific humidity near the ground. The vertical structure of two PCAPs, one in the past and one around 2050, is next investigated in detail. For this purpose, the WRF (Weather Research and Forecasting) model, forced by MAR for the worst-case scenario (SSP5–8.5), is used at a high resolution (111 m). The PCAP episodes are carefully selected from the MAR data so that a meaningful comparison can be performed. The future episode is warmer at all altitudes than the past episode (by at least 4 ∘C) and displays a similar inversion height, which are very likely generic features of future PCAPs. The selected episodes also have similar along-valley wind but different stability, with the future episode being more stable than the past episode. Overall, this study shows that the atmosphere in the Grenoble valleys during PCAP episodes tends to be slightly less stable in the future under the SSP5–8.5 scenario, and statistically unchanged under the SSP2–4.5 scenario, but that very stable PCAPs can still form.

BackgroundThe management of chronic pain may involve an array of tools, including radiofrequency thermocoagulation (Rf-Tc) of sensory nerve terminals. Like many other invasive procedures, Rf-Tc can generate anxiety in a lot of patients, either during the expectation of the procedure or in the course of it. Virtual reality hypnosis (VRH) is a promising tool for managing anxiety and pain in several situations, but its anxiolytic property has not been investigated in participants with chronic pain and going through a Rf-Tc procedure.ObjectivesThe goal of this study was to evaluate the effectiveness of VRH for reducing self-assessed anxiety in participants with chronic pain, when received in preparation for Rf-Tc.Materials and methodsThis prospective, controlled trial was conducted in the Interdisciplinary Algology Centre of the University Hospital of Liège (Belgium). Participants were assigned to two groups: VRH or control (usual care). Assessment was carried-out at 4 time points: T0 (one week before Rf-Tc); T1 (pre-intervention, on the day of Rf-Tc); T2 (immediately after the VRH intervention outside of the Rf-Tc room); and T3 (right after Rf-Tc). Medical, sociodemographic data, anxiety trait and immersive tendencies were collected at T0. Anxiety state and pain intensity were assessed at each time points. Satisfaction was examined at T3.ResultsForty-two participants were quasi-randomly assigned to the VRH or control group. No statistically significant interaction group by time was observed regarding all measured variables, including primary endpoint. However, a significant effect of time was found for anxiety and pain when considering both groups together, toward a progressive reduction.ConclusionIn the context of our study, there appears to be no significant effect of VRH at reducing anxiety in participants with chronic pain undergoing Rf-Tc. Anxiety decreases along the procedure, while pain is attenuated by the local anesthetic infiltration of the Rf site. Our results suggest that the presence of a caregiver throughout the procedure might explain the progressive decrease in anxiety. Future randomized controlled trials are needed to precisely study the effectiveness of the VRH tool, and the possibility of using it as a complementary approach for anxiety during invasive procedures.

We study the impact of climate change on wintertime atmospheric blocking over Europe focusing on the frequency, duration, and size of blocking events. These events are identified via the weather type decomposition (WTD) methodology applied on the output of climate models of the Coupled Model Intercomparison Project phase 6 (CMIP6). Historical simulations and two future scenarios, SSP2-4.5 and SSP5-8.5, are considered. The models are evaluated against the reanalysis, and only a subset of climate models, which better represent the blocking weather regime in the recent-past climate, is considered for the analysis. We show that the spatio-temporal characteristics of recent-past atmospheric blocking are in agreement with previous studies that define blocking events with blocking indexes. We find that frequency and duration of blocking events remain relatively stationary over the 21st century. We define a methodology that relies on the WTD for the blocking event identification in order to quantify the size of the blocking events, and we find that the blocking size is basically unchanged in the future.

Replacing ordinary Portland cement-based materials with alkali-activated industrial wastes is often limited because of significant volume changes occurring in these materials at early age. This experimental study aims to quantify the extent of the volume changes and explore the underlying mechanisms of pastes composed of slag and fly ash (ratio 50:50) which are activated by sodium hydroxide and sodium silicate. Eight compositions were tested, with silica modulus (Ms) varying between 1.04 and 1.58 and with solution-to-binder ratios (S/B) varying between 0.47 and 0.70. Specimen length changes in sealed conditions are monitored by applying repeated thermal variations in an adapted AutoShrink device and are accompanied by isothermal calorimetry, uniaxial compressive strength, and internal relative humidity (IRH) tests. This way, the temporal evolutions of autogenous strains, the coefficient of thermal expansion (CTE), the heat release, the apparent activation energy (Ea), the IRH and the strength are determined and compared to each other. Both the measured autogenous shrinkage and CTEs are rather large; they amount to 4,000–5,000 μm/m and roughly 40 μm/m/°C, respectively, at material ages of 2 weeks. An increase in S/B leads to a decrease in autogenous shrinkage and an increase in CTE. An increase in the Ms causes a decrease in both the autogenous shrinkage and the CTE. Most strikingly, autogenous shrinkage evolves linearly with the cumulative heat released by the binders. The IRH remains continuously above 94% during the first 2 weeks. The apparent activation energy amounts to roughly 74 kJ/mol and is virtually unaffected by S/B and Ms.