Mapping peat depth using a portable gamma-ray sensor and terrain attributes

Pristine peatlands being excellent storage for terrestrial Carbon (C) play a crucial role in regulating climate and water and provide several important ecosystem services. However, peatlands have been heavily altered (e.g., by draining the water table), increasing greenhouse gas (GHG) emissions. Restoring peatlands requires a comprehensive characterization, including knowledge of peat depth (PD; m). Traditionally, this requires the physical insertion of a push probe, which is time-consuming and labor-intensive. It has been shown that non-invasive proximal sensing techniques such as electromagnetic induction and ground penetrating radar can add value to PD data. In this research, we want to assess the potential of proximally sensed gamma-ray (γ-ray) spectrometry (i.e., potassium [K], thorium [Th], uranium [U], and the count rate [CR]) and terrain attributes data (i.e., elevation, slope, SAGAWI, and MRVBF) to map PD either alone or in combination across a small (10 ha) peatland area in ØBakker, Denmark. Here, the PD varies from 0.1 m in the south to 7.3 m in the north. We use various prediction models including ordinary kriging (OK) of PD, linear regression (LR), multiple LR (MLR), LR kriging (LRK), MLR kriging (MLRK) and empirical Bayesian kriging regression (EBKR). We also determine the minimum calibration sample size required by decreasing sample size in decrements (i.e., n = 100, 90, 80,…, 30). We compare these approaches using prediction agreement (Lin’s concordance correlation coefficient; LCCC) and accuracy (root mean square error; RMSE). The results show that OK using maximum calibration size (n = 108) had near perfect agreement (0.97) and accuracy (0.59 m), compared to LR (ln CR; 0.65 and 0.78 m, respectively) and MLR (ln K, Th, CR and elevation; 0.85 and 0.63 m). Improvements are achieved by adding residuals; LRK (0.95 and 0.71 m) and MLRK (0.96 and 0.51 m). The best results were obtained using EBKR (0.97 and 0.63 m) given all predictions were positive and no significant change in agreement and standard errors with the decrement of calibration sample size (e.g., n = 30). The results have implications towards C stocks assessment and improved land use planning to control GHG emissions and slow down global warming

Assessing the suitability of ground-penetrating radar for peat imaging

Peatland conservation and restoration are prominent in slowing global warming. A thorough comprehension of peat inventory, especially the thickness, bulk density, water table levels, and geological setting, is necessary to plan and initiate rewetting strategies and to calculate emission savings. The conventional mapping methods involving push probes and boreholes are not only cost- and labor-intensive, but they also provide only localized measurements. Among the geophysical sensors, while electromagnetic induction (EMI) and gamma-ray spectrometry have proven to be suitable for mapping specific attributes, ground penetrating radar (GPR) is seen as the industry’s standard recommendation. However, the success rate can be highly variable in reality depending on the peatland type, and ignoring this can lead to the waste of numerous resources. To demonstrate this, in this study, we compare GPR survey transects performed on two different peatland types (a bog vs. a fen) with two different antenna center frequencies (i.e., 160 MHz and 450 MHz). Electrical resistivity tomography was also performed along the same transects to complement and guide our interpretation. Our results suggest that while GPR surveys are suitable in rain-fed oligotrophic bogs, less to no success rate can be anticipated in minerotrophic fens. Forward modeling using gprMax is also shown to substantiate these findings. Thus, knowledge of the peatland type constitutes crucial information for sensor selection. If in doubt, we recommend performing on-the-go EMI surveys before initiating GPR surveys, as electrical conductivity might be sufficient on its own for peatland characterization. Moreover, EMI is also useful for predicting GPR performances

Fictions historiques pour la jeunesse en France et au Québec

Comme leurs aînés, les jeunes lecteurs apprécient les fictions historiques, les romans, les BD, les albums qui les plongent dans un univers révolu. Les collections en édition jeunesse se multiplient pour donner à lire le passé, comprendre le présent ou parfois simplement proposer des histoires dans lesquelles l’Histoire constitue un décor aux couleurs attrayantes. Fictions historiques pour la jeunesse en France et au Québec s’attache à décrire ce phénomène éditorial, littéraire et culturel. En s’appuyant sur des travaux portant sur la France et sur le Québec, cet ouvrage montre que la littérature jeunesse n’échappe pas aux conséquences économiques et culturelles de la mondialisation et qu’il existe bien des formes de fictions historiques communes. Pour autant, le contexte sociopolitique de production rend plus ou moins aisée l’évocation de certains pans du passé. Or, l’histoire et la mémoire participent, de manière particulièrement sensible, des constituants des consciences nationales. Ce livre s’inscrit au croisement de plusieurs domaines : littérature, histoire, histoire des arts, ou études culturelles. De l’Antiquité à octobre 1970, des trappeurs aux héroïnes du Grand Siècle, de la mémoire de l’esclavage à celle de la guerre d’Algérie, les questionnements variés permettent d’appréhender les fictions historiques pour la jeunesse dans leur diversité

Rilpivirine in HIV-1-positive women initiating pregnancy: to switch or not to switch?

International audienceBackgroundSafety data about rilpivirine use during pregnancy remain scarce, and rilpivirine plasma concentrations are reduced during second/third trimesters, with a potential risk of viral breakthroughs. Thus, French guidelines recommend switching to rilpivirine-free combinations (RFCs) during pregnancy.ObjectivesTo describe the characteristics of women initiating pregnancy while on rilpivirine and to compare the outcomes for virologically suppressed subjects continuing rilpivirine until delivery versus switching to an RFC.MethodsIn the ANRS-EPF French Perinatal cohort, we included women on rilpivirine at conception in 2010–18. Pregnancy outcomes were compared between patients continuing versus interrupting rilpivirine. In women with documented viral suppression (<50 copies/mL) before 14 weeks of gestation (WG) while on rilpivirine, we compared the probability of viral rebound (≥50 copies/mL) during pregnancy between subjects continuing rilpivirine versus those switching to RFC.ResultsAmong 247 women included, 88.7% had viral suppression at the beginning of pregnancy. Overall, 184 women (74.5%) switched to an RFC (mostly PI/ritonavir-based regimens) at a median gestational age of 8.0 WG. Plasma HIV-1 RNA nearest delivery was <50 copies/mL in 95.6% of women. Among 69 women with documented viral suppression before 14 WG, the risk of viral rebound was higher when switching to RFCs than when continuing rilpivirine (20.0% versus 0.0%, P = 0.046). Delivery outcomes were similar between groups (overall birth defects, 3.8/100 live births; pregnancy losses, 2.0%; preterm deliveries, 10.6%). No HIV transmission occurred.ConclusionsIn virologically suppressed women initiating pregnancy, continuing rilpivirine was associated with better virological outcome than changing regimen. We did not observe a higher risk of adverse pregnancy outcomes