Interpretation of glacier mass change within the Upper Yukon Watershed from GRACE using Explainable Automated Machine Learning Algorithms.

Glaciers play a vital role in providing water resources for drinking, agriculture, and hydro-electricity in many mountainous regions. As global warming progresses, accurately reconstructing long-term glacier mass changes and comprehending their intricate dynamic relationships with environmental variables are imperative for sustaining livelihoods in these regions. This paper presents the use of eXplainable Machine Learning (XML) models with GRACE and GRACE-FO data to reconstruct long-term monthly glacier mass changes in the Upper Yukon Watershed (UYW), Canada. We utilized the H2O-AutoML regression tools to identify the best performing Machine Learning (ML) model for filling missing data and predicting glacier mass changes from hydroclimatic data. The most accurate predictive model in this study, the Gradient Boosting Machine, coupled with explanatory methods based on SHapley Additive eXplanation (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME) analyses, led to automated XML models. The XML unveiled and ranked key predictors of glacier mass changes in the UYW, indicating a decrease since 2014. Analysis showed decreases in snow water equivalent, soil moisture storage, and albedo, along with increases in rainfall flux and air temperature were the main drivers of glacier mass loss. A probabilistic analysis hinging on these drivers suggested that the influence of the key hydrological features is more critical than the key meteorological features. Examination of climatic oscillations showed that high positive anomalies in sea surface temperature are correlated with rapid depletion in glacier mass and soil moisture, as identified by XML. Integrating H2O-AutoML with SHAP and LIME not only achieved high prediction accuracy but also enhanced the explainability of the underlying hydroclimatic processes of glacier mass change reconstruction from GRACE and GRACE-FO data in the UYW. This automated XML framework is applicable globally, contingent upon sufficient high-quality data for model training and validation

Spatial heterogeneity of high-affinity H2 oxidation activity in agricultural soil profile

Soil H2 oxidizing bacteria metabolize H2 from the atmosphere, but soil carbon substrates and environmental factors influence their distribution in the soil profile. We conducted a field survey of the spatial distribution of H2 content and high-affinity H2 oxidation activity in the soil profile (5 cm, 15 cm, and 35 cm) and between the soybean rhizosphere and bulk soil. We found the H2 content declined exponentially with soil depth, but potential H2 oxidation activity was consistent at all soil depths. The rhizosphere soil had 66% more high-affinity H₂ oxidation activity than bulk soil. Simultaneous presence of H2 and carbon likely facilitates mixotrophic growth of H2 oxidizing bacteria in the rhizosphere. </br

Using relative gas diffusivity to highlight soil compaction issues with possible effects on N efficiency in grain corn production, southern Quebec, Canada.

It has long been suggested that soil compaction indices should be monitored as part of a routine soil management program. Moreover, in addition to properties related to storage of gases and fluid within a bulk volume (i.e., bulk density [BD] and air porosity [θa]), some authors have suggested that properties linked to fluid and gas exchanges such as gas diffusion and hydraulic conductivity should be used to assess the physical health of soils. Given the risk of severe compaction due to the increasing size of farm equipment and the lack of long rotation in cash crop production, data on soil storage and exchange properties need to be collected. The objective of this study was to assess the physical soil health of the top 30 cm of 18 southern Quebec corn fields using a set of indicators. The data were also used to determine crop response to nitrogen fertilization. The results showed that over 93% of the corn fields had a relative gas diffusivity (Ds/Do) below the 0.03 threshold at both 15- and 30-cm depth, suggesting substantial crop growth limitations. They also showed that around 40% of the soils had subsurface drainage problems linked to a low saturated hydraulic conductivity (49% at 15 cm and 47% at 30 cm lower than 0.001 cm s−1). The levels of relative gas diffusivity were low, not only limiting crop growth but also likely reducing nitrogen efficiency through increasing risk of denitrification. Moreover, the results suggest that in some fields, high yields can be achieved with as little as 60 and up to 215 kg of nitrogen per hectare, and that slow-draining soils will have a very poor response to N fertilization, leading to lower net revenues and nitrogen losses. Overall, the findings suggest that appropriate soil conservation and water management practices based on soil physical health criteria like relative gas diffusivity and hydraulic conductivity must be implemented to maintain or improve soil productivity and health in the face of climate change

Measuring varve thickness using micro-computed tomography (µCT): a comparison with thin section.

X-ray micro-computed tomography (µCT) scans were performed on four varved sediment cores collected in Grand Lake (Labrador) and previously studied with thin sections. These scans allowed us to investigate the possibility of using µCT as a substitute for thin sections to carry out counts and thickness measurements of varved sediments. Comparing varve counts of these two methods, µCT counts are slightly higher than the ones made with thin sections. The difference in counts suggests that the petrographic study and a scanning electron microscope (SEM) analysis of a thin section remain necessary for determining the varve character of the laminae. Yet, µCT allows measurements in multiple directions, improving the robustness of the counts and avoiding the manufacturing of continuous thin sections along a sediment sequence. As for the thickness measurement, the µCT analyses were made in two perpendicular directions. Not surprisingly, measurements made on the same cutting plane as the thin section are quite similar to the ones made on the latter. However, there are significant differences with measurements made on the perpendicular plane. This highlights the need to perform varve thickness measurements in at least two perpendicular directions for better estimates of varved sediment thicknesses. In addition, the study illustrates that µCT is an effective way to select the least deformed zones with parallel varves to carry out the best possible thickness measurements

A holistic approach towards the integration of geothermal energy in remote northern communities.

Geothermal energy is increasingly considered as an energy alternative across off-grid indigenous communities in northern Canada. These communities primarily rely on diesel for electricity and a combination of oil, propane, wood, and diesel for heating. Burwash Landing, the seat of the Kluane First Nation government in Yukon Territory, Canada, is located on the shore of Łù'àn Män (Kluane Lake) at the base of the St. Elias Mountains and near a step-over in the Denali fault. A Play fairway analysis of southwestern Yukon highlights the geothermal favourability around Burwash Landing. Over the past 15 years, Kluane First Nation has taken significant steps to reduce greenhouse gas emissions and drilled a community-led geothermal exploration borehole in 2012 (KFN‑L; 387 m). KFN‑L was drilled northeast of the Denali fault in Quaternary sediments. In 2021, the Yukon Geological Survey drilled a second exploration borehole (DRGW; 220 m) in bedrock to the southwest. This provided a unique opportunity to contrast geothermal context on either side of the Denali fault. The temperature gradients in KFN-L and DRGW are 45 and 35 ⁰C km-1, respectively. Fibre-optic digital temperature sensing was used to produce high-resolution thermal conductivity profiles for each borehole. These results led to a heat flux estimation of ⁓ 90 mW m-2 at both sites. The field results were then combined into a coupled groundwater flow and heat transfer model to evaluate temperature at depth. This poster presents the evaluation of the geothermal potential around Burwash Landing, considering the influence of the Denali fault on local geothermal resources alongside socio-economic factors. Both the local geology and socio-economic factors are combined to offer Kluane First Nation context-informed recommendations for the integration of geothermal energy into their energy budget

Numerical modeling of the long-term poromechanical performance of a deep enhanced geothermal system in northern Québec.

This study numerically investigates the thermo-poromechanical effects in a Canadian geothermal reservoir caused by long-term fluid production and injection. Using finite element modeling, it explores pore pressure diffusion and thermal dynamics, incorporating both the geological structure of the rock mass and faults. The simulations utilize the IAPWS (International Association for the Properties of Water and Steam) equations to model fluid density and viscosity, ensuring realistic representations of heterogeneous pressure fields. The system replicates a doublet configuration within a faulted zone, featuring two hydraulically stimulated fractures. The primary aim is to assess the likelihood of fault reactivation under varying in-situ stress conditions over a 100-year geothermal operation. Results show that stress distribution is largely influenced by thermal stresses along the fluid circulation pathway, with fluid velocity and temperature gradients affecting reservoir stability. Minimal pore pressure changes highlight the dominant role of thermal stresses in controlling fault behavior. The analysis indicates no potential for fault reactivation, as slip tendency values remain below the critical threshold, even when accounting for reduced mechanical properties using the Hoek-Brown criterion. Thermal effects continue to influence the surrounding rock throughout the operational period, suggesting that the reservoir maintains mechanical stability conducive to sustained geothermal production and injection. These findings provide valuable insights into the long-term safety and behavior of geothermal reservoirs, offering important implications for future geothermal energy development and management strategies

Assessing the potential for Atlantic salmon (<i>Salmo salar</i>) colonization of Nunavik’s Arctic and subarctic rivers by 2070–2100.

In Nunavik, Québec, Canada, Atlantic salmon (Salmo salar) populations reach their northern limit in four rivers of southern Ungava Bay. With projected river warming from climate change, this study assesses the potential for Atlantic salmon to colonize new rivers in Nunavik by modelling water temperatures and evaluating river accessibility. Migration barriers were identified with a literature review, topographic data, and satellite imagery. Water temperatures were modelled with a generalized additive model using ERA5-Land air temperature, observed daily mean temperatures, and water surface temperature estimated from Landsat imagery. Our projections indicate an average increase of the rivers mean summer temperatures of 1.2–2.7 °C by the end of the century, enhancing thermal conditions in current salmon rivers with more days with optimal growth temperatures (16–20 °C) while still having limited days with thermal stress (>22 °C). By 2100, other Ungava Bay rivers may be colonized, as most are accessible and expected to reach more suitable temperatures. However, Nunavik’s northernmost rivers would remain too cold and colonization of the Hudson Bay watershed appears less likely due to the inaccessibility of most rivers and their distance from established anadromous populations

The Slow Maturation of Local Democracy: The Evolution of Electoral Parameters at the Municipal Level in Quebec since 1855

In Canada, the evolution of the right to vote, the nomination process, and the frequency and organization of elections have not been the same at the municipal, provincial and federal levels, even though they share the same political foundations. In Quebec, more specifically, there is a clear gap between practices at the municipal level and at higher levels of government. Among the municipalities, statutes have also shifted across time, differing especially between the mid- and late 19th century, and this remains the case today for Montreal and the other municipalities of the province. Not much research has been done on the historical evolution of these differences between the three levels of government, or between Montreal and the other municipalities. In this context, this article engages in an exploratory analysis of the legislation on the subject, including over 20 laws adopted since 1855. Our analysis shows that the democratization of local governance in Quebec has certainly been marked by substantial transformations since the mid-19th century, but also by significant divergences with the other levels of government, and between Montreal and other municipalities. More generally, this exploratory analysis sheds light on the way in which certain contemporary characteristics of the municipal scene, both in Montreal and within other municipalities of Quebec, reflect the weight of the past, allowing us to better grasp the current political dynamics at the local leve

SI/II Pocket of Ras: An Opportunity for a Once "Undruggable" Target

Mutations on the Ras-family of small GTPases are among the most common molecular oncogenic drivers, with the HRas isoform being primarily associated with head-and-neck and genito-urinary cancers. Although once considered "undruggable," recent efforts have identified a structurally conserved surface pocket in the Ras family, designated the SI/II pocket, situated near the binding site of the guanidine exchange factor (GEF) SOS1. The SI/II pocket may represent a potential target site for a pan-Ras drug. A crystal structure representing the native state of GDP-bound HRasG12V was generated to characterize the topology of the SI/II pocket. This native-state structure was employed, together with the published structure of GppNHp-bound HRasG12V in state 1 (PDB ID: 4EFM), as a base for further molecular dynamics simulations exploring the conformational dynamics of the SI/II pocket via four generated synthetic HRas model structures. Our results show that the SI/II pocket is natively inaccessible in GDP-bound HRas yet becomes accessible in state 1 GppNHp-bound HRas systems, an effect that seems to be more evident in the mutated enzyme. This points to the GTP-bound state as a most promising target for Ras inhibitors directed at the SI/II pocket. Occlusion of the SI/II pocket is dictated by the spatial position of the alpha 2 alpha helix in relation to the protein core, with alpha 2 residue Y71 acting as a "tyrosine toggle" capable of restricting the pocket access.</br

Firefighting, other protective service occupations and prostate cancer risk: a pooled analysis of three case-control studies

Background: Prostate cancer (PCa) is the most frequent incident cancer among males in industrialized countries, but little is known about its aetiology. A role for occupational exposures is suggested. Occupational exposure as a firefighter, a protective service occupation (PSO), is classified as carcinogenic to humans by the International Agency for Research on Cancer, with limited evidence in humans for PCa. We studied the association between PSO and PCa risk considering tumour aggressiveness and screening practices. Methods: The EPIdemiological study of Prostate Cancer (EPICAP), the Prostate cancer and Environment Study (PROtEuS) and the MultiCase-Control study in common tumours in Spain (MCC-Spain) are population-based case-control studies, conducted respectively in France, Canada, Spain, in 2005–2014 in men ≤ 85 years old, including overall 3,859 incident cases and 4,359 controls frequency-matched on age. Participants were interviewed face-to-face using general and occupational questionnaires covering all jobs held in career, coded according to the 1988 International Standard Classification of Occupations. Unconditional logistic regressions estimated associations between PSO and PCa, after adjusting for potential confounders. Two sets of analyses were conducted, without and with consideration of screening. The latter is believed to yield the main findings since less subject to detection bias. Results: When restricting controls to those recently screened, men employed as firefighters ≥ 10 years had increased risk (OR (Odds ratio) = 2.01 [95% confidence interval] [1.02; 3.97]) of non-aggressive PCa. Positive associations for non-aggressive PCa among men employed &#60; 10 years as police officers (OR = 2.53 [1.07; 5.96]) and police inspectors and detectives (OR = 6.75 [1.47; 30.96]) were observed. Very few cases in PSO were characterized by aggressive tumours. Conclusions: Findings from this large population-based study corroborate the higher PCa risk previously reported among firefighters, but only for non-aggressive tumours. Screening practices had a substantial impact on risk estimates. Future studies should investigate specific exposures, and account for PCa aggressiveness and individual screening patterns.</br