Laval University
  • Québec, Quebec, Canada
Recent publications
With the participation of distributed energy resources (DERs) in inertia emulation, voltage control and primary frequency response, distinct angle and voltage dynamics are introduced in a conventional distribution network. These additional low-frequency dynamics emanating from a pre-dominantly resistive distribution network influence the mode properties of system oscillations uniquely. For better control and partitioning of active distribution network during emergency conditions coherent participation of DERs in local and inter-area modes need to be evaluated. In this work, fundamental factors affecting the bus coherency of distribution system are analyzed. It introduces a concept of coherency duality between pre-dominantly resistive and inductive distribution networks along with unique effect of source and control interactions by DERs. The work discovers pre-dominance of voltage based coherency criteria for active power flow control/islanding in resistive sub-networks and angle based criteria for inductive sub-networks, due to the reverse relation between state and power variables. Dynamic coherency changes inflicted by DER variabilities like different control and source interactions, increased penetration level, change in the spatial distribution of DERs, and dynamic loading are presented in the work. The proposition is tested for modified IEEE-39 bus systems with 33 bus 132/33/11/0.4 kV and 2182 bus 20/0.4 kV distribution networks in DigSILENT/PowerFactory.
Background Patients with disorders of consciousness (DoC) are a challenging population prone to misdiagnosis with limited effective treatment options. Among neuromodulation techniques, transcutaneous auricular vagal nerve stimulation (taVNS) may act through a bottom-up manner to modulate thalamo-cortical connectivity and promote patients’ recovery. In this clinical trial, we aim to (1) assess the therapeutic clinical effects of taVNS in patients with DoC; (2) investigate the neural mechanisms underlying the effects of its action; (3) assess the feasibility and safety of the procedure in this challenging population; (4) define the phenotype of clinical responders; and (5) assess the long-term efficacy of taVNS in terms of functional outcomes. Methods We will conduct a prospective parallel randomized controlled double-blind clinical trial investigating the effects of taVNS as a treatment in DoC patients. Forty-four patients in the early period post-injury (7 to 90 days following the injury) will randomly receive 5 days of either active bilateral vagal stimulation (45 min duration with 30s alternative episodes of active/rest periods; 3mA; 200-300μs current width, 25Hz.) or sham stimulation. Behavioural (i.e., Coma Recovery Scale-Revised, CRS-R) and neurophysiological (i.e., high-density electroencephalography, hd-EEG) measures will be collected at baseline and at the end of the 5-day treatment. Analyses will seek for changes in the CRS-R and the EEG metrics (e.g., alpha band power spectrum, functional connectivity) at the group and individual (i.e., responders) levels. Discussion These results will allow us to investigate the vagal afferent network and will contribute towards a definition of the role of taVNS for the treatment of patients with DoC. We aim to identify the neural correlates of its action and pave the way to novel targeted therapeutic strategies. Clinical trial registration n° NCT04065386.
Human type 1 17β-hydroxysteroid dehydrogenase (17β-HSD1),a member of the short-chain dehydrogenase/reductase family, catalyzes the last step in the bioactivation of the most potent estrogen estradiol with high specificity and is thus involved in estrogen-dependent diseases. As an oxidoreductase, 17β-HSD1 can utilize both triphosphate and diphosphate cofactors in reaction at the molecular level, but more specific with triphosphate cofactor. The NADPH is much higher than NADP+ in living cells leading to preliminary reduction action. The enzyme also showed substrate-induced inhibition unprecedented in other members of 17β-HSDs. Our previous study elucidated the structural mechanism of substrate inhibition is due to the reversely bound estrone (E1) in the substrate-binding pocket of the enzyme resulting in a dead-end complex. However, the effect of the cofactor preference on the substrate inhibition of the enzyme is not yet clear. In the present study, we solved the ternary crystal structures of 17β-HSD1 in complex with E1 and cofactor analog NAD+. Combined with molecular dynamics simulation using the enzyme with NADH/NADPH and different oriented E1 (normally oriented, E1N; reversely oriented, E1R), such ternary structure provides a complete picture of enzyme-substrate-cofactor interactions. The results reveal that different cofactors and substrate binding mode affect the allosteric effect between the two subunits of the enzyme. And the results from MD simulations confirmed that His221 plays a key role in the formation of dead-end complex in NADPH complex, and the absence of stable interaction between His221 and E1R in the NADH complex should be the main reason for its lack of substrate inhibition.
Background: The potential benefit of using larger or smaller transcatheter heart valves (THV) in patients with borderline aortic annulus measurement (BAM) remains uncertain. The objective of this study was to evaluate the clinical outcomes associated with the selection of larger or smaller THV in the context of BAM. Methods: This was a multicenter observational study including patients who underwent transcatheter aortic valve replacement with the SAPIEN 3 or SAPIEN 3 Ultra-valve systems (Edwards Lifesciences, Irvine, CA) from April 2014 to June 2021. BAM was defined according to the manufacturer sizing chart and included the following annulus areas: 314 to 346, 400 to 430, 500 to 546 mm2. A 1:1 propensity score matching was used to compare outcomes of patients with larger or smaller THV. Results: From a total of 2467 patients, BAM was identified in 852 patients (34.5%). A larger and smaller THV was selected in 338 (39.7%) and 514 patients (60.3%) patients, respectively. The choice of a larger THV was associated (before and after propensity matching) with a higher risk of new-onset left bundle branch block (HR, 2.25 [95% CI, 1.39-3.65; P=0.001) and permanent pacemaker implantation (HR, 1.86 [95% CI, 1.11-3.09]; P=0.016) without any impact on gradients or the risk of moderate or severe paravalvular regurgitation at discharge (HR, 0.78 [95% CI, 0.41-1.45]; P=0.427). The risk of periprocedural complications such as aortic rupture and tamponade was low (<1%) and similar between groups. Conclusions: In patient with BAM, selecting a larger SAPIEN 3/Ultra THV increased the risk of conduction disturbances without any benefit on valve hemodynamics and clinical outcomes.
This article focuses on multilevel governance applied to health organizations in Québec (Canada). The objective is to understand the action levers that facilitate the adaptation of the services toward migrant populations. This type of population establishes itself as an excellent tracer case to analyze the adaptation process, its fractalization and its involvement with the Environment. The dynamics between the actors and their self-organization takes part in the development of a multilevel governance. Interactions with the Environment—both internal and external—highlight the development of networks that emerge from the field and are then implemented at strategic levels in the organizations. The presence of connectivity actors within the organization and the Environment is established. The context, the bonds of trust between the actors and the credibility of the policymakers are reflected as important factors. However, connectivity actors cannot be successful without the support and contribution of the more “hierarchical” actors. Eight action levers are revealed by the analysis. We categorized them in 3 functions: administrative, enabling, and emerging. The levers of the administrative and emerging functions require that the levers of the enabling function be credible and legitimate and be able to support them for the adaptation to spread throughout the healthcare organization, regardless of the scope or policymaking level. The fractal function facilitates this process, by combining connectivity actors with the implementation of connectivity structures.
Evidence points out that increasing plant productivity associated with greater erect shrub abundance alters soil organic carbon (SOC) stocks in the Arctic. However, the underlying plant economic traits remain poorly examined, which limits our understanding of plant–environment interactions driving tundra carbon cycling. We explored how erect shrub abundance leads to SOC variation in a High Arctic tundra (Bylot Island, Nunavut, Canada), where the only erect shrub, Salix richardsonii, has settled along currently active and abandoned channel zones of alluvial fans. The effects of vegetation and local environmental changes on SOC were evaluated through a paired sampling of soil materials and plant aboveground functional traits associated with plant carbon supply and nutrient demand processes. The occurrence of S. richardsonii, characterized by a tenfold increase in aboveground biomass, induced a 28% increase in SOC compared to adjacent plots dominated by prostrate shrubs and graminoids. Yet, this vegetation effect was solely observed along active channels, where higher SOC was associated with greater leaf and stem biomass. A path analysis showed that shrub leaf area index and total leaf nutrient content best represented plant carbon supply and nutrient demand dynamics, respectively, and jointly regulated SOC variation. This study underscores that vegetation structural changes associated with increasing erect shrub abundance in the Arctic can promote soil organic carbon storage, but that this pattern may be mediated by strong plant–environment interactions. Accounting for changes in functional traits driving plant carbon supply and nitrogen demand proves important for a better mechanistic understanding of how shrubification impacts tundra carbon cycling.
Despite numerous contributions made to the modelling of precipitation kinetics, no theory seems to have unified all the concepts required to simulate the nucleation, growth, and ripening processes as one continuous process. In the present work, a novel approach was used to reshape the master equation calculating the evolution of the size distribution, so that the zero-flux condition can represent a steady-state evolution. This modification was made by introducing explicitly the probability for clusters to grow or to dissolve in each size class. The expression found to calculate this probability allowed the calculation of the entire evolution of the size distribution from the first step of nucleation to the final stages of the ripening process. The winners-losers concept also allowed for a better definition of the average condensation and evaporation rates, which were found by applying the thermodynamic extremum principle and assuming that a population of clusters of a given size behaves on the average as one cluster of the same size and submitted to the same driving forces. Furthermore, the thermodynamic extremum principle allowed us to show that the subcritical growth regime must be interface controlled to maximise the dissipation rate of energy. The computational scheme based on the new theory was applied to calculate the size evolution of precipitates in the Al-Cu system. The influence of aging temperature on the evolution of the number density of precipitates during homogeneous nucleation was found to agree with experimental estimations of number densities made on uniformly distributed θ′-Al2Cu precipitates.
This article summarizes 10 years of research on an alternative actor providing peer support in Quebec workplaces since 1983: the Quebec Federation of Labor's Union Social Stewards Peer Support Network. Such work fills the gap in research on unions’ capacity to act with respect to workplace mental health and take collective control of preventing its injuries. Data were collated through 12 discussions (120-min) groups and some 60 semi-structured individual (90-min) interviews. Our findings highlight the importance of local unionism in maintaining workplace mental health. They also reiterate unions’ need to consider mental health injuries in the workplace as opportunities for reconstructing their strategies so as to rethink work and help institute a truly preventive strategy involving all stakeholders.
To recover species at risk, it is necessary to identify habitat critical to their recovery. Challenges for species with large ranges (thousands of square kilometres) include delineating management unit boundaries within which habitat use differs from other units, along with assessing amounts of and threats to habitat over time. We developed a reproducible framework to support the identification of critical habitat for wide-ranging species at risk. The framework (i) reviews species distribution and life history; (ii) delineates management units across the range; (iii) evaluates and compares current and (iv) potential future habitat and population size; and (v) prioritizes areas within management units based on current and future conditions under various scenarios of climate change and land-use. We used Canada Warbler ( Cardellina canadensis ) and Wood Thrush ( Hylocichla mustelina ) in Canada as case studies. Using geographically weighted regression models and cluster analysis to measure spatial variation in model coefficients, we found geographic differences in habitat association only for Canada Warbler. Using other models to predict current habitat amount for each species in different management units, then future habitat amount under land use and climate change, we projected that: 1) Canada Warbler populations would decrease in Alberta but increase in Nova Scotia; and 2) Wood Thrush populations would increase under most scenarios run in Quebec, New Brunswick, and Nova Scotia, except in Ontario. By comparing results from future scenarios and spatial prioritization exercises, our framework can be used to support identification of critical habitat in a way that incorporates climate and land-use projections.
The use of plug-in electric vehicles (PEV) and their developing technology can create new challenges to the smart power system. The type, method, and time of charging electric vehicles are also other issues. Allocating and determining the optimal capacity of electric vehicle charging stations (EVCS) is related to the technical requirements of the distribution network. This is economically important for the construction of charging stations. This paper proposes a new approach for optimal siting and sizing of PEV charging stations in a coupled electrical and transportation network. This work presents the problem from a techno-economic point of view of the electrical network as a multi-objective problem with the objectives of simultaneously reducing the cost of building EVCSs and active power losses. The Pareto method is used to solve the problem and to display optimal points. In order to carry out the simulation, the proposed method is tested on a case study of the standard IEEE 37-bus network with a 25-node transport system and the proposed solution in the subject environment. The Floyd-Warshall method is utilized to determine the shortest travel routes for PEVs. The obtained results confirm the effectiveness of the optimal planning of PEV charging stations.
Human herpesvirus 6 (HHV-6) infects almost all humans and integrates into the telomeres of latently infected cells to persist in the host for life. In addition, HHV-6 can also integrate into the telomeres of germ cells, which results in about 80 million individuals worldwide who carry the virus in every cell of their body and can pass it on to their offspring.
The present article proposes to broaden the understanding of the life courses of women executives to include an experiential perspective of meaning built around their different life projects. Our study is based on a qualitative approach employing narrative research methodology to analyze interviews with a sample of 51 women executives. Our findings reveal key experiences and events and a diversity of transitions between hierarchical levels that characterize their career development. They also show a number of possible configurations of rapprochement, integration, distancing, or separation between the different spheres of life and their influence on executive careers through ascending, lateral, or descending career paths. These findings contribute to a deeper insight into the complex career paths of women executives and underscore the value of including these different dimensions when considering guidance support strategies for this clientele.
The past decade has witnessed increasing evidence for a crucial role played by glial cells, notably astrocytes, in Alzheimer’s disease (AD). To provide novel insights into the roles of astrocytes in the pathophysiology of AD, we performed a quantitative ultrastructural characterization of their intracellular contents and parenchymal interactions in an aged mouse model of AD pathology, as aging is considered the main risk factor for developing AD. We compared 20-month-old APP-PS1 and age-matched C57BL/6J male mice, among the ventral hippocampus CA1 strata lacunosum-moleculare and radiatum, two hippocampal layers severely affected by AD pathology. Astrocytes in both layers interacted more with synaptic elements and displayed more ultrastructural markers of increased phagolysosomal activity in APP-PS1 versus C57BL6/J mice. In addition, we investigated the ultrastructural heterogeneity of astrocytes, describing in the two examined layers a dark astrocytic state that we characterized in terms of distribution, interactions with AD hallmarks, and intracellular contents. This electron-dense astrocytic state, termed dark astrocytes, was observed throughout the hippocampal parenchyma, closely associated with the vasculature, and possessed several ultrastructural markers of cellular stress. A case study exploring the hippocampal head of an aged human post-mortem brain sample also revealed the presence of a similar electron-dense, dark astrocytic state. Overall, our study provides the first ultrastructural quantitative analysis of astrocytes among the hippocampus in aged AD pathology, as well as a thorough characterization of a dark astrocytic state conserved from mouse to human.
Calcium phosphate (Ca-P) surface coating is a simple but effective way to enhance both corrosion resistance and biocompatibility of ZK60 magnesium alloy. However, cell compatibility on different Ca-P layers coated on ZK60 alloy has seldom been investigated. In this study, the effects of type, morphology and corrosion protection of several Ca-P coatings formed at pH 6.5, 7.8 and 10.2 on cell behavior were examined by using an osteoblastic cell line MC3T3-E1. Furthermore, in vivo behavior in rabbits of the alloy coated with the optimum Ca-P layer was also studied. It was found that the surface factors governed the cell morphology and density. The coating morphology plays a dominant role in these surface factors. The sample coated at pH 7.8 showed the best cellular biocompatibility, suggesting that the hydroxyapatite (HAp) layer formed at pH 7.8 was the optimum coating. In rabbits, this optimum coating enhanced remarkably the corrosion resistance of the alloy. During implantation, the outermost crystals of the HAp coating were shortened and thinned due to the dissolution of HAp caused by the body fluid of the rabbits. It is indicated that ZK60 alloy coated at pH 7.8 can be applied as a biodegradable implant.
Objective This study examined the utility of a biopsychosocial model to explain both higher body mass index (BMI) and disordered eating. The study was designed to examine the predictors of higher BMI and a number of measures of disordered eating (dietary restraint, drive for muscularity, drive for thinness, binge eating, and compensatory behaviour). Method Young adults (N = 838) recruited from seven countries, grouped into four regions (Europe, North American countries, Australia, Japan), completed an online survey, with each completion being 12 months apart. The survey included assessments of BMI and disordered eating, and a range of biological, psychological and sociocultural factors expected to predict both outcomes. Results Results revealed unique patterns of association between predictors and BMI as well as different measures of disordered eating in the four geographical regions. Conclusions The findings identify the specific nature of biopsychosocial factors that predict both higher BMI and different aspects of disordered eating. They also demonstrate that caution needs to be exercised in generalising findings from one country to other countries.
Purpose There is an ongoing debate on the appropriateness of actuarial tools with women. Such tools were developed with data collected mainly from convicted men and were then applied to convicted women. The LS/CMI, the most widely known and used instrument to assess criminogenic needs and evaluate the risk of recidivism, is one such scale. Within this debate, some argue that the LS/CMI works just as well with both genders and some argue that, despite its good predictive validity with women, the LS/CMI doesn’t consider their very own pathways into crime and is, therefore, unfit for women. Methods We conducted a Differential Item Functioning (DIF) analysis of the LS/CMI items using Raju’s method with data fitted into a Rasch model to determine which items seem biased and to what extent. We also compared predictive validity coefficients to see if the LS/CMI dimensions and total scores predict criminal recidivism similarly between men or women. Results Several items of the LS/CMI seem much easier to endorse for men then they are for women. Significant differences were observed with intermediate and large effect size in many dimensions. Despite the discrepancies found at the item level of the LS/CMI, very few differences in predictive validity were found at the dimension and test level. Conclusions Our study gives credence to both sides in the debate on the appropriateness of risk tools with women. Those defending the gender neutrality of the LS/CMI will likely highlight how similarly it predicts male and female criminal recidivism, regardless of the differences expected and found at the item level. Those arguing against its neutrality will highlight how several items of the LS/CMI seem biased and unable to distinguish male and female pathways into crime, even though the tool, as a whole, predicts recidivism just as well with women, even slightly better.
This paper proposes an intelligent battery charging scheme for hybrid electric vehicles (HEVs) with a fuel cell as the primary energy source and solar photovoltaic (PV) and battery as the auxiliary energy sources. While dealing with the PV, a minimized oscillation-based improved perturb and observe (I-P&O) maximum power point (MPP) tracking (MPPT) scheme is designed to mitigate the impact of oscillations around MPP and loss of tracking direction. The DC-DC boost and DC-DC buck power converters are connected in a cascade manner to harvest optimal power from PV and as a charging circuit for HEV, respectively. An intelligent fuzzy logic-based proportional integral derivative (PID) (F-PID) controller is employed for the buck converter to get the constant voltage and constant current for the effective charging of the battery. The two primary objectives of this work are (1) maximum utilization of the designed PV array via the I-P&O MPPT scheme to enhance the system efficacy, reduce system cost, and reduce complexity. (2) To obtain minimum battery losses and an enhanced life cycle of HEV. The proposed MPPT scheme provides a maximum 99.80% tracking efficiency of the considered PV array at an insolation level of 1000 W/m 2. Moreover, almost nominal voltage and current ripples have appeared in HEV's proposed intelligent battery charging circuit.
Conservation approaches that efficiently protect multiple values, such as the umbrella species concept, have been widely promoted with expected dramatic ecosystem changes. Due to its social and cultural importance, and recent declining trends, boreal populations of woodland caribou have been suggested as potential umbrella species for other declining taxa, such as boreal landbirds. We propose a generic pixel‐based umbrella index that focuses on fine‐grained habitat overlaps. In light of ongoing conservation efforts worldwide implementing area‐based targets (e.g., 30% by 2030), we used a random neutral model as baseline, as opposed to a no‐conservation scenario, which has been used elsewhere. We found that the conservation efficiency of caribou as an umbrella for 71 co‐occurring landbirds—three of which are priority species—in the Northwest Territories, Canada, is generally lower than our random model, as 53% of the species presented negative umbrella index medians with the interquartile range not overlapping zero. We conclude that in cases where area‐based targets drive decision‐making and the issue at stake involves identifying which areas to conserve—not whether to conserve—woodland caribou may be a leaky umbrella for most co‐occurring landbird species and these might need complementary conservation actions to be brought in from the rain.
Arctic regions are disproportionately affected by atmospheric warming, with cascading effects on multiple surface processes. Atmospheric warming is destabilizing permafrost, which could weaken riverbanks and in turn increase the lateral mobility of their channels. Here, using timelapse analysis of satellite imagery, we show that the lateral migration of large Arctic sinuous rivers has decreased by about 20% over the last half-century, at a mean rate of 3.7‰ per year. Through a comparison with rivers in non-permafrost regions, we hypothesize that the observed migration slowdown is rooted in a series of indirect effects driven by atmospheric warming, such as bank shrubification and decline in overland flow and seepage discharge along channel banks, linked in turn to permafrost thaw. As lower migration rates directly impact the residence timescales of sediment and organic matter in floodplains, these surprising results may lead to important ramifications for watershed-scale carbon budgets and climate feedbacks.
En 2019-2021, notre équipe de recherche de la Faculté de médecine de l’Université Laval a mis sur pied une intervention visant à impliquer activement des patients représentant une diversité de profils socioéconomiques et de santé dans les ateliers de discussion d’un cours obligatoire du doctorat de premier cycle en médecine. Le but de l’intervention était de soutenir le développement de la réflexivité chez les étudiants. À l’hiver 2020, en raison de la pandémie de COVID-19, la mise en œuvre de l’intervention a dû être adaptée afin de l’ajuster au basculement en ligne des activités de formation universitaires. Cet article vise à exposer les principaux enjeux et les leçons tirées du passage en ligne de notre intervention et ayant pu influencer les effets de l’intervention. Ces enjeux touchent principalement l’accès des patients à l’espace participatif et la relation d’apprentissage. Les technologies de l’information et de la communication (TIC) ont constitué, souvent à travers des pratiques et outils nouveaux dont on connaît peu les répercussions pédagogiques à long terme, le moyen dominant d’interagir, de participer et d’apprendre en contexte de COVID-19. La réflexion proposée contribuera à une meilleure compréhension des répercussions pédagogiques de ces pratiques.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
17,302 members
Sékou Samadoulougou
  • Institut Universitaire de Cardiologie et de Pneumologie de Québec
Muhammad Mohiuddin
  • Department of Management
Emmanuel Bujold
  • Faculty of Medicine
2325, rue de l'Université, G1V 0A6, Québec, Quebec, Canada
Head of institution
Sophie D'Amours