Modélisation de la contamination microbienne et des concentrations d'un micropolluant dans les débordements de réseaux d'égouts unitaires

RÉSUMÉ Les concentrations élevées de contaminants durant les événements de pluie sont une préoccupation majeure pour la protection des sources d'eau potable. Les concentrations élevées de contaminants microbiens et des micropolluants ont été souvent détectées dans les débordements. Afin de protéger les sources d'eau potable, de concevoir des systèmes de traitement de débordement, ou d'évaluer les impacts du changement climatique sur les systèmes de drainage urbain dans le futur, une meilleure compréhension de la dynamique des contaminants de transport est nécessaire et peut être faite en partie, grâce à l'application de la simulation des modèles. Par conséquent, le but de cette recherche était de modéliser la contamination microbienne et les concentrations d’un micropolluant des eaux usées dans les rejets de débordement d'un réseau pseudo-sanitaire en milieu urbain dans la région métropolitaine de Montréal pour les événements survenus à l'automne 2009 et l'été 2010. Le logiciel SWMM (Storm Water Management Model) a été utilisé dans cette étude. Le contaminant microbien étudié était Escherichia coli en raison de son importance comme indicateur pour évaluer la qualité de l'eau brute au Québec et ailleurs. La carbamazépine a été également choisie comme micropolluant des eaux usées à modéliser, car il est persistant et généralement observé dans les eaux usées. Sur la base de la revue de la littérature, ces deux contaminants sont associés à des matières en suspension qui ont également été modélisées dans cette étude. Le modèle SWMM élaboré a été calibré avec un événement d'octobre 2009 et validé avec des données provenant de six événements surveillés de précipitations. Le modèle validé a été utilisé pour simuler la dynamique du transport microbienne et micropolluants, afin de prédire les concentrations maximales de contaminants durant les débordements qui présentent une période de risque élevé pour les prises d'eau potable.----------ABSTRACT Elevated concentrations of contaminants during wet weather are a major concern for the protection of drinking water sources. High concentrations of microbial contaminants and micropollutants were frequently found in overflow discharges. In order to protect sources of drinking water, to des gn overflow treatment systems, or to evaluate future impacts of climate change on urban drainage systems, a better understanding of contaminant transport dynamics is required and can be, in part, achieved through the application of simulation models. Therefore, the purpose of this research was to model the concentration of microbial contaminant and wastewater micropollutant in the overflow discharges of an urban pseudo-sanitary and combined drainage basin in the Greater region of Montreal for events occurring in autumn 2009 and summer 2010. The Storm Water Management Model (SWMM) was used in this study. The microbial contaminant studied was Escherichia coli because of its importance as an indicator for assessing raw water quality in Québec and elsewhere. Carbamazepine was chosen as the wastewater micropollutant to model since it is persistent and it is generally observed in sewage. Based upon the literature revue, these two contaminants are associated with suspended solids, thus, total suspended solids were also modelled in this study. The model was calibrated with an event from October 2009 and validated with data from other 6 monitored events. The validated model was used to simulate the dynamics of microbial and micropollutant transport, to predict peak contaminant concentrations at the beginning of overflow events which present a period of high potential risk for drinking water intakes

Part-Based Models Improve Adversarial Robustness

We show that combining human prior knowledge with end-to-end learning can improve the robustness of deep neural networks by introducing a part-based model for object classification. We believe that the richer form of annotation helps guide neural networks to learn more robust features without requiring more samples or larger models. Our model combines a part segmentation model with a tiny classifier and is trained end-to-end to simultaneously segment objects into parts and then classify the segmented object. Empirically, our part-based models achieve both higher accuracy and higher adversarial robustness than a ResNet-50 baseline on all three datasets. For instance, the clean accuracy of our part models is up to 15 percentage points higher than the baseline's, given the same level of robustness. Our experiments indicate that these models also reduce texture bias and yield better robustness against common corruptions and spurious correlations. The code is publicly available at https://github.com/chawins/adv-part-model.Comment: Code can be found at https://github.com/chawins/adv-part-mode

Unpacking How Decentralized Autonomous Organizations (DAOs) Work in Practice

Decentralized Autonomous Organizations (DAOs) have emerged as a novel way to coordinate a group of (pseudonymous) entities towards a shared vision (e.g., promoting sustainability), utilizing self-executing smart contracts on blockchains to support decentralized governance and decision-making. In just a few years, over 4,000 DAOs have been launched in various domains, such as investment, education, health, and research. Despite such rapid growth and diversity, it is unclear how these DAOs actually work in practice and to what extent they are effective in achieving their goals. Given this, we aim to unpack how (well) DAOs work in practice. We conducted an in-depth analysis of a diverse set of 10 DAOs of various categories and smart contracts, leveraging on-chain (e.g., voting results) and off-chain data (e.g., community discussions) as well as our interviews with DAO organizers/members. Specifically, we defined metrics to characterize key aspects of DAOs, such as the degrees of decentralization and autonomy. We observed CompoundDAO, AssangeDAO, Bankless, and Krausehouse having poor decentralization in voting, while decentralization has improved over time for one-person-one-vote DAOs (e.g., Proof of Humanity). Moreover, the degree of autonomy varies among DAOs, with some (e.g., Compound and Krausehouse) relying more on third parties than others. Lastly, we offer a set of design implications for future DAO systems based on our findings

What Drives the (In)stability of a Stablecoin?

In May 2022, an apparent speculative attack, followed by market panic, led to the precipitous downfall of UST, one of the most popular stablecoins at that time. However, UST is not the only stablecoin to have been depegged in the past. Designing resilient and long-term stable coins, therefore, appears to present a hard challenge. To further scrutinize existing stablecoin designs and ultimately lead to more robust systems, we need to understand where volatility emerges. Our work provides a game-theoretical model aiming to help identify why stablecoins suffer from a depeg. This game-theoretical model reveals that stablecoins have different price equilibria depending on the coin's architecture and mechanism to minimize volatility. Moreover, our theory is supported by extensive empirical data, spanning $1$ year. To that end, we collect daily prices for 22 stablecoins and on-chain data from five blockchains including the Ethereum and the Terra blockchain

The Efficacy of a Newly Developed Cueing Device for Gait Mobility in Parkinson’s Disease

Background. External cues are effective in improving gait in people with Parkinson’s disease (PD). However, the most effective cueing method has yet to be determined. Objective. The aim of this study was to compare the immediate effects of using visual, auditory, or somatosensory cues on their own or in combination during walking compared to no cues in people with PD. Methods. This was a single blinded, randomly selected, controlled study. Twenty people with PD with an age range of 46–79 years and Hoehn and Yahr scores of 1–3 were recruited. Participants were studied under 4 cueing conditions; no cue, visual, auditory, or somatosensory cues, which were randomly selected individually or in a combination. Results. A repeated measures ANOVA with pairwise comparisons using Bonferroni correction showed that any single or combination of the cues resulted in an improvement in gait velocity and stride length compared to no cue. Some significant differences were also seen when comparing different combinations of cues, specifically stride length showed significant improvements when additional cues were added to the light cue. The statistically significant difference was set at p<0.05. Conclusions. Walking using visual, auditory, or somatosensory cues can immediately improve gait mobility in people with PD. Any or a combination of the cues tested could be chosen depending on the ability of the individual to use that cue

Distribution of Burkholderia pseudomallei within a 300-cm deep soil profile: implications for environmental sampling.

The environmental distribution of Burkholderia pseudomallei, the causative agent of melioidosis, remains poorly understood. B. pseudomallei is known to have the ability to occupy a variety of environmental niches, particularly in soil. This paper provides novel information about a putative association of soil biogeochemical heterogeneity and the vertical distribution of B. pseudomallei. We investigated (1) the distribution of B. pseudomallei along a 300-cm deep soil profile together with the variation of a range of soil physico-chemical properties; (2) whether correlations between the distribution of B. pseudomallei and soil physico-chemical properties exist and (3) when they exist, what such correlations indicate with regards to the environmental conditions conducive to the occurrence of B. pseudomallei in soils. Unexpectedly, the highest concentrations of B. pseudomallei were observed between 100 and 200 cm below the soil surface. Our results indicate that unravelling the environmental conditions favorable to B. pseudomallei entails considering many aspects of the actual complexity of soil. Important recommendations regarding environmental sampling for B. pseudomallei can be drawn from this work, in particular that collecting samples down to the water table is of foremost importance, as groundwater persistence appears to be a controlling factor of the occurrence of B. pseudomallei in soil

Influence of soil physical and chemical properties and their seasonal variation on the occurrence and distribution of the occurrence and distribution of Burkholderia pseudomallei in a rice field in central of Laos

Burkholderia pseudomallei (BP) bactérie commune des sols tropicaux, provoque une maladie grave, la mélioïdose. Cette thèse, basée sur un travail de terrain dans le centre de la RDP Lao où BP est endémique, vise à clarifier les déterminants de la distribution de BP dans le sol en fonction des conditions biogéochimiques du sol et climatiques, à des échelles emboîtées. PB a été identifiée dans le sol jusqu'à 300 cm de profondeur, à des concentrations variables (maximales en dessous de 100 cm), à la fois à l'échelle du millimètre, en lien avec l'état d'oxydation du fer, et à l'échelle du profil du sol. La variabilité saisonnière des concentrations de BP, plus marquée près de la surface qu'en profondeur, est cohérente avec sa persistance accrue dans les couches saturées d'eau tout au long de l'année. Cette thèse démontre l'importance de considérer la complexité du sol pour mieux comprendre l'écologie de BP.Burkholderia pseudomallei (BP) a pathogenic bacterium found in tropical soils, causes a severe disease, melioidosis. This thesis, based on field work in the main region of BP endemicity in Lao PDR, aims to clarify the determinants of BP distribution in soil. We applied a multi-scale approach to characterize the distribution of BP in relation with soil physico-chemical variability and highlight seasonal variations in BP distribution. BP occurred at all soil depths down to 300 cm but its concentrations varied drastically, both at the millimetre scale, concomitantly with the oxidation state of iron, and at the soil profile scale, unexpectedly reaching peak values below 100 cm. Seasonal variability of BP concentrations was higher in shallow than deep soil horizons, consistent with increased BP persistence in layers saturated with water year round. This thesis demonstrate the importance of considering the complexity of soil to better understand the ecology of BP

Influence des propriétés physiques et chimiques du sol et de leur variation saisonnière sur l'occurrence et la distribution de Burkholderia pseudomallei dans une rizière au centre du Laos

Burkholderia pseudomallei (BP) bactérie commune des sols tropicaux, provoque une maladie grave, la mélioïdose. Cette thèse, basée sur un travail de terrain dans le centre de la RDP Lao où BP est endémique, vise à clarifier les déterminants de la distribution de BP dans le sol en fonction des conditions biogéochimiques du sol et climatiques, à des échelles emboîtées. PB a été identifiée dans le sol jusqu'à 300 cm de profondeur, à des concentrations variables (maximales en dessous de 100 cm), à la fois à l'échelle du millimètre, en lien avec l'état d'oxydation du fer, et à l'échelle du profil du sol. La variabilité saisonnière des concentrations de BP, plus marquée près de la surface qu'en profondeur, est cohérente avec sa persistance accrue dans les couches saturées d'eau tout au long de l'année. Cette thèse démontre l'importance de considérer la complexité du sol pour mieux comprendre l'écologie de BP.Burkholderia pseudomallei (BP) a pathogenic bacterium found in tropical soils, causes a severe disease, melioidosis. This thesis, based on field work in the main region of BP endemicity in Lao PDR, aims to clarify the determinants of BP distribution in soil. We applied a multi-scale approach to characterize the distribution of BP in relation with soil physico-chemical variability and highlight seasonal variations in BP distribution. BP occurred at all soil depths down to 300 cm but its concentrations varied drastically, both at the millimetre scale, concomitantly with the oxidation state of iron, and at the soil profile scale, unexpectedly reaching peak values below 100 cm. Seasonal variability of BP concentrations was higher in shallow than deep soil horizons, consistent with increased BP persistence in layers saturated with water year round. This thesis demonstrate the importance of considering the complexity of soil to better understand the ecology of BP