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Field deployment and analysis of hydraulic tomography experiments with periodic slug tests in an anisotropic littoral aquifer.
No full textAccurate mapping of the heterogeneity of hydraulic properties, including hydraulic conductivity (Kh) and its anisotropy (Kv/Kh), is crucial for predicting groundwater flow and solute transport in aquifers. This study investigates the use of hydraulic tomography with periodic signals to map Kh, Kv/Kh and specific storage (Ss) in an unconsolidated littoral aquifer. The periodic signals were generated by the movement of a rod numerically controlled by a winch, which allowed the signal amplitude and period to be imposed. Thirty periodic slug tests with periods of 150, 300 and 600 s were conducted between isolated intervals in a source well and an observation well, generating 120 head responses. Numerical inversion in the time domain used the rod-induced flow rates and associated heads to estimate the heterogeneous fields. Significant differences in head amplitude and phase shift between test intervals at different locations highlighted the heterogeneity of the aquifer. The inversion results for single and combined periods are consistent with the values of previous studies and the heterogeneous nature of the littoral aquifer. Comparison of models from different periods revealed slight spatial and statistical variations in hydraulic properties and different hydraulic behavior when tested with independent hydraulic tests. While the fundamentals of understanding the information in the different periodic signals need to be further clarified, this study advances the application of hydraulic tomography under real field conditions and highlights its effectiveness in characterizing aquifer heterogeneity and anisotropy
IceEB: An ensemble-based method to map river ice type from radar images.
No full textThis paper introduces IceEB, i.e., an innovative ensemble-based method that is designed to automate mapping of river ice types using radar imagery. Its goal is the merger of outcomes from three classifiers (IceMAP-R, RIACT, and IceBC) through ensemble-estimation, resulting in a highly performant and fully automated river ice-type map, which is applicable under all meteorological conditions. The first step of our research is the development of a meta-classifier and a confidence estimation index, then we validate our method using ground-truth datasets and finally compare the performance between IceEB and the original classifiers. The anticipated outcome was a map exhibiting superior results compared to individual classifiers. Validation and comparison of IceEB employed six RADARSAT-2 HH-HV C-band images that were selected from historical datasets of Quebec and Alberta rivers (Canada). IceEB integrates RADARSAT-2 satellite imagery, a digital elevation model, and a river mask, undergoing preprocessing tasks before activating the three initial classifiers. The meta-classifier then performs ensemble-based classification, yielding a legend comprised of water, sheet ice and rubble ice. This approach facilitates broad participation in validation data collection, differentiation between ice covers and ice jams, and minimization of assumptions regarding ice formation. We conclude that IceEB successfully combines existing radar remote sensing ice- classification models to create accurate river ice-type maps. IceEB’s ensemble-based approach outperforms individual classifiers, achieving overall accuracy >91 % for each class. Shortcomings of the original classifiers are effectively offset through parallel use, resulting in marked improvements in automation and generalizability across diverse Canadian meteorological conditions
Quorum sensing and DNA methylation play active roles in clinical Burkholderia phase variation
No full textPhenotypic diversity in bacteria often results from adaptation to changing environmental conditions, exemplified by variable colony morphotypes. In Burkholderia pseudomallei, discrete genomic alterations and modulation of gene expression facilitate adaptation. Adapted variants of species within the Burkholderia cepacia complex (Bcc) often lose the pC3 virulence megaplasmid, impacting their colony morphology and their production of virulence factors. In this study, we characterize variants arising in Burkholderia ambifaria clinical isolates using proteomics and phenotypic tests and show that some of them have retained the pC3, indicating a distinct phase variation mechanism at play in this Bcc species. Interestingly, variants of B. ambifaria strains CEP0996 (pC3-null) and HSJ1 (pC3-positive) still share similarities in phenotypes controlled by the Cep quorum-sensing (QS) system. We further investigated the role of QS in B. ambifaria HSJ1 phase variation and confirmed that the Cep QS system is important for the emergence of variants. Given that DNA methylation is a key epigenetic factor regulating virulence factors in Burkholderia cenocepacia, we hypothesized that adenosine DNA methylation also governs phase variation in B. ambifaria HSJ1. By deleting the genes encoding putative adenosine DNA methyltransferases, we discovered that an orphan type II DNA methyltransferase inhibits the emergence of phase variants. This study is the first to demonstrate that quorum sensing and adenosine DNA methylation are two antagonistic systems independently controlling phase variation in B. ambifaria.IMPORTANCESome Burkholderia species are pathogenic to plants, animals, or humans. In immunocompromised individuals, and people suffering from cystic fibrosis, infection from the Burkholderia cepacia complex (Bcc) can lead to "cepacia syndrome." In northern Australia and southeast Asia, melioidosis caused by Burkholderia pseudomallei is prevalent among native population, particularly among people with diabetes, chronic lung or kidney disease or alcoholism. Burkholderia's phenotypic plasticity, including colony morphotype variation (CMV), enables rapid adaptation to diverse environments, enhancing its survival and pathogenicity. This study reveals phase variation as a new CMV mechanism within the Bcc group and is the first to report that quorum sensing and DNA methylation are involved in phase variation. Understanding the underlying mechanisms of CMV could lead to the development of targeted therapies against these highly antibiotic-tolerant bacteria.</br
Gestational exposure to environmental chemical mixtures and cognitive abilities in children: A pooled analysis of two North American birth cohorts
No full textBACKGROUND: Gestational exposures to single toxic chemicals have been associated with cognitive deficits in children, but few studies have explored chemical mixtures. OBJECTIVES: To evaluate the associations between gestational chemical biomarker mixtures and cognitive abilities in children from two prospective cohorts. METHODS: This study includes 617 birthing parent-child pairs from the Health Outcomes and Measures of the Environment (HOME) and Maternal-Infant Research on Environmental Chemicals (MIREC) Studies. We measured 29 chemical biomarkers (metals, persistent organic pollutants, perfluoroalkyl substances, organophosphate esters, phenols, phthalates, organophosphate pesticides, and parabens) in pregnant individuals during early pregnancy and their children's cognitive abilities at ages 3 to 5 years using Wechsler Intelligence Scales. We assessed linear associations using quantile g-computation and non-linear associations using Bayesian Kernel Machine Regression (BKMR) methods, adjusted for covariates. RESULTS: Using quantile g-computation, we observed overall null associations between the chemical biomarker mixture and cognitive outcomes among preschool-age children. Although statistical significance was not attained for child sex as an effect modifier, our stratified analysis unveiled a moderate divergence in association trends. We noted a marginal inverse trend between the chemical biomarker mixture and cognitive scores [Full-Scale Intelligence Quotient (FSIQ) and Performance Intelligence Quotient (PIQ)] among males. Using quantile g-computation and BKMR methods, we observed that PBDE47, PFHxS, and di-ethyl organophosphates commonly contributed towards a decline in FSIQ scores in males. Among males, a quartile increase in the chemical biomarker mixture was associated with a 0.64-point decrease (95% CI: -2.59, 1.31) in the FSIQ score and a 1.59-point decrease (95% CI: -3.72, 0.54) in the PIQ score. CONCLUSION: In this study, we observed a weak negative trend between the gestational chemical biomarker mixture and cognitive scores (FSIQ/PIQ) among males. Further studies are needed to confirm the findings between the longitudinal chemical biomarkers and child cognitive scores at school ages.</br
Complementarity of multiple in-situ techniques for spatiotemporal assessment of groundwater/surface-water exchanges
No full textL’hétérogénéité des matériaux géologiques d’un au site joue un rôle crucial dans l’interaction entre les eaux souterraines (ESO) et les eaux de surface (ESU), en particulier dans les écosystèmes sensibles à l’afflux d’eaux souterraines; par exemple, les habitats des salmonidés sont influencés par l’apport localisé d’eaux souterraines dans les cours d’eau. Bien que de nombreuses méthodes soient apparues pour mieux comprendre les mécanismes régissant l’interaction entre ESO et ESU, peu d’études comparent directement ces méthodes. L’objectif de cette étude est donc d’évaluer les forces et les limites d’une méthode innovante de traçage thermique actif pour quantifier le rôle de l’hétérogénéité du lit de la rivière sur les échanges entre ESO et ESU. Cette méthode a été comparée à plusieurs techniques établies telles que les compteurs d’infiltration, les piézomètres et le traçage thermique passif sur un site de la rivière Sainte-Marguerite au Québec, Canada. La variation spatiale mesurée des taux d’échange due à la présence d’un banc de sable avec des matériaux grossiers s’est révélée statistiquement significative. En outre, l’analyse temporelle a permis d’identifier les variations du flux d’ESO, même pendant la saison froide, lorsque le flux d’ESO était censé être limité en raison du gel du sol et de la faible infiltration à partir de la surface du sol recouvert de neige. Les compteurs d’infiltration et le traçage thermique actif ont permis une analyse spatiale de l’interaction ESO–ESU, tandis que les piézomètres avec enregistreurs de niveau d’eau et le traçage thermique passif avec des capteurs de température installés dans le lit de la rivière ont permis d’identifier les variations temporelles des taux d’échange ESO–ESU. La combinaison de capteurs de température et d’un câble chauffant a été utilisée pour la première fois comme outil de traçage thermique actif et a montré un bon potentiel pour évaluer les propriétés thermiques du lit de la rivière et les taux d’infiltration de ESO dans la rivière.
ABSTRACT
Site-specific heterogeneity in geological materials plays a crucial role in groundwater (GW) and surface water (SW) interaction, especially in ecosystems sensitive to groundwater influx; for example, salmonid habitats are influenced by localized GW input to streams. While numerous methods have emerged to better understand mechanisms governing GW–SW interaction, few studies compare these methods directly. Therefore, the objective of this study is to evaluate the strengths and limitations of an innovative active heat tracing method to quantify the role of riverbed heterogeneity on GW–SW exchanges. This method was compared with several established techniques such as seepage meters, piezometers, and passive heat tracing at a field site on the Sainte-Marguerite River in Quebec, Canada. The measured spatial variation of the exchange rates due to the presence of a sandbar with coarse materials was shown to be statistically significant. Additionally, temporal analysis helped to identify variations of GW flux even during the cold season when GW flux was expected to be limited due to frozen ground and low infiltration from the snow-covered ground surface. Seepage meters and active heat tracing allowed for spatial analysis of GW–SW interaction, while piezometers with water level loggers and passive heat tracing with installed temperature sensors in the riverbed were convenient for identifying temporal variation of GW–SW exchange rates. The combination of temperature sensors and a heating cable was used for the first time as a tool for active heat tracing and showed good potential to evaluate riverbed thermal properties and GW seepage rates in the river
Integrating Local and Global Features in a Convolutional Vision Transformer for Wetland Mapping.
No full textAccurate classification of hyperspectral images is particularly challenging in wetlands regions, where land cover classes are highly similar. While integrating local and global features can enhance feature representation and improve classification accuracy, this approach remains largely unexplored in wetland mapping (WM) applications. In addition, existing methods often suffer from information loss during feature extraction and integration processes. To address these challenges, this article introduces a convolutional vision transformer (ConViT), which combines convolutional neural networks and vision transformers (ViTs) to simultaneously leverage local and global features for WM. ConViT consists of four components: 1) local feature extraction using DenseNet; 2) a novel local embedding for tokenization that preserves spatial relationships; 3) a convolutional-transformer block (CTB); and 4) a softmax-based classifier. By integrating DenseNet with squeeze-and-excitation (SE) layers, ConViT enhances feature reuse and boosts sensitivity to subtle variations in wetland classes. Our contributions include a dual-input CTB with skip connections for richer feature extraction, a unique local embedding method to maintain spatial context and efficient global-local feature fusion. ConViT outperforms two traditional and seven deep learning classifiers for WM across four datasets. In addition, ConViT exhibits superiority in visual inspection, statistical significance tests, and focused comparison experiments, which pinpoints its potential use for WM. The source codes of this work will be available at https://github.com/halizz821/ConViT
Le rapport à l’argent chez les adultes du Québec : enquête sur ses origines et variations dans le temps
Get PDFCe projet de recherche analyse la relation que les gens entretiennent avec l’argent ainsi que son évolution au cours des parcours de vie. La relation ainsi mise en lumière est nommée « rapport à l’argent » et est conceptualisée comme étant une forme d’habitus. Neuf répondants qui ont entre 45 et 59 ans et qui habitent le Québec auront été passés en entretiens qualitatifs pour ce faire. L’analyse produite est divisée en deux parties principales : la première se penche sur les caractéristiques du rapport à l’argent, la seconde sur la manière avec laquelle il peut ou non évoluer au cours des étapes de vie. Les conclusions tirées stipulent tout d’abord que le rapport à l’argent peut se décrire à l’aide de versions modifiées et étendues des figures de Simmel, ensuite que l’enfance joue un rôle primordial dans la formation initiale de ce rapport et que celui-ci est relativement durable et perdure généralement à travers le temps tant qu’il n’est pas remis en question. Cette remise en question se fait habituellement avec l’aide d’un partenaire romantique.
This research project analyzes the relationship people have with money and its evolution during their life course. This relationship is then called “relationship to money” and is conceptualized as a form of habitus. Nine respondents ranging from 45 to 59 years old who are currently living in the province of Québec have been interviewed to produce the data. The analysis thus produced is divided into two parts: the first one treats of the characteristics of the relationship to money, the second one treats of the ways in which this relationship may or may not evolve during different life stages. The conclusions state firstly that relationship to money can be described with the help of Simmel’s archetypes, given those have been reworked and expanded, and secondly that relationship to money built during childhood is relatively durable and usually persists through the life stages until it is called into question. This process usually requires the help of a close romantic partner
Resilient climate urbanism and the politics of experimentation for adaptation
No full textCities are increasingly pursuing actions to become more resilient in the face of climate change and to seize related economic growth opportunities. Recent contributions have argued that “climate urbanism” is emerging as a hegemonic trend that is structuring climate adaptation with a focus on the selective securing of vital infrastructure for growth, promoting an apolitical vision of resilience and exacerbating inequalities. Developing situated understandings of these dynamics and their contestation seems key. We analyse this trend of climate urbanism in a specific setting of climate adaptation experiment: living labs. We investigate and intervene on two key processes of the politics of climate experimentation – making for compelling urban projects and focusing on infrastructure reconfiguration – whereby living labs could challenge or, conversely, amplify negative trends of climate urbanism. Our research in Montreal shows the value of understanding the subjectivities of the practitioners involved and the fields of political struggles where adaptation lands. Although the negative trends of climate urbanism appear very resilient and living labs have important limitations, we believe they can be used to muddle through pathways for more debates, equity and justice in climate adaptation
Trend and teleconnection analysis of temperature extremes in New South Wales, Australia.
No full textThis study investigates possible trends and teleconnections in temperature extremes in New South Wales (NSW), Australia. Daily maximum and minimum temperature data covering the period 1971–2021 at 26 stations located in NSW were used. Three indices, which focus on daily maximum temperature, daily minimum temperature, and average daily temperature in terms of Excessive Heat Factor (EHF) were investigated to identify the occurrence of heatwaves (HWs). The study considered HWs of different durations (1-, 5-, and 10-days) in relation to intensity, frequency, duration, and their first occurrence parameters. Finally, the influences of three global climate drivers, namely – the El Niño/Southern Oscillation (ENSO), the Southern Annular Mode (SAM), and the Indian Ocean Dipole (IOD) were investigated with associated heatwave attributes for extended Austral summers. In this study, an increasing trend in both hot days and nights was observed for most of the selected stations within the study area. The increase was more pronounced for the last decade (2011–2021) of the investigated time period. The number, duration and frequency of the heatwaves increased over time considering the EHF criterion, whereas no particular trend was detected in cases of TX90 and TN90. It was also evident that the first occurrence of all the HWs shifted towards the onset of the extended summer while considering the EHF criterion of HWs. The correlations between heatwave attributes and climate drivers depicted that heatwave over NSW was positively influenced by both the IOD and ENSO and negatively correlated with SAM. The findings of this study will be useful in formulating strategies for managing the impacts of extreme temperature events such as bushfires, floods, droughts to the most at-risk regions within NSW
Feasibility of using freshwater microalgae to remove triclosan from aqueous media.
No full textTriclosan, [5-chloro-2-(2,4-dicholophenoxy)phenol] (TCS), a broad-spectrum antimicrobial agent found in many personal care products, has raised concerns due to its presence in the environment. TCS has been associated to harmful effects, including oxidative damage in golfish cells, increased lipid peroxidation in clams, and disruption of the hypothalamic-pituitary-gonadal axis in Catla fish, and its potential contribution to antimicrobial resistance. This study evaluates the feasibility of using two freshwater microalgae species to remove TCS from aqueous media by 1) determining the toxicity of TCS on algal cultures, 2) evaluating their potential to remove TCS, and 3) identifying the TCS degradation kinetics. The toxicity test assessed various concentrations of TCS (0.06, 0.10, 0.20, 0.30, 1 mg L−1) on Chlorella vulgaris and Scenedesmus obliquus growth. Results showed that C. vulgaris was entirely inhibited by concentrations exceeding 0.10 mg L−1. In comparison, S. obliquus tolerated up to 0.30 mg L−1 after six days of lag phase, but 1 mg L−1 was toxic for both species. The removal efficiency achieved by S. obliquus was between 79 % and 94 % across all concentrations tested, while C. vulgaris achieved 70–95 % removal only in concentrations lower than 0.10 mg L−1. The degradation kinetics revealed that the TCS half-life in wastewater was 1.3 days when S. obliquus was present, highlighting its potential to enhance pollutant removal. This study provides insights into the use of S. obliquus for removing contaminants from natural environments, contributing to understanding TCS dynamics in ecosystems with the presence of microalgae