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Quantification de la relation entre la défoliation des peuplements forestiers causée par la tordeuse des bourgeons de l’épinette (Choristoneura fumiferana Clem.) et les écailles du papillon de la tordeuse des bourgeons de l’épinette retrouvées dans les sédiments lacustres annuels boréaux
Get PDFLa tordeuse des bourgeons de l’épinette ((Choristoneura fumiferana Clem.)TBE) est un insecte indigène présent dans toutes les régions du Canada. Il se nourrit au printemps des aiguilles des conifères tels que le Sapin Baumier (Abies balsamea L. (Mill.)) et l’épinette noire (Picea mariana (Mill.) B.S.P.). Après plusieurs années de défoliation consécutive par la larve de la TBE, les arbres présentent un taux de mortalité élevé, entraînant une grande perte économique pour l’industrie du bois d’oeuvre. À l’ère où les changements climatiques sont l’une des principales préoccupations sociales, économiques et scientifiques, il est important de bien comprendre la fréquence et l’intensité des perturbations passées afin de mieux prédire celles qui auront lieu dans le futur. Pour ce faire, la paléoécologie est utilisée pour retracer les épidémies de la TBE qui ont eu lieu dans le passé. Une nouvelle méthode originale a été développée et il s’agit des écailles du papillon de la TBE retrouvées dans les sédiments lacustres. La présente étude vise à comprendre le patron de sédimentation des écailles du papillon de la TBE dans les sédiments lacustres boréaux en fonction de la défoliation autour des lacs afin d’approfondir les connaissances de ce nouveau paléo-indicateur. Plus précisément, les objectifs sont d’identifier si celles-ci sédimentent rapidement en plus de vérifier s’il existe une relation entre le nombre d’écailles retrouvées dans les sédiments lacustres annuels et la défoliation totale du peuplement adjacent. Aussi, la proximité des trappes à sédiments au bord des lacs à l’étude ainsi que la valeur de NDVI des peuplements forestiers entourant le lac ont été testées comme variable potentielle. Les résultats obtenus ont démontré que les écailles du papillon de la TBE sédimentaient dans l’année suivante de leur production, ce qui est expliqué par les brassages bisannuels des lacs boréaux qui remettent en suspension les particules ainsi que la structure des écailles permettant leur flottabilité. Aussi, le nombre d’écailles retrouvées dans les sédiments lacustres annuels est significativement plus élevé pour les sites à l’étude où l’épidémie était sévère, mais sans différence statistique entre une période endémique et le tout début d’une épidémie. Ce résultat est expliqué par le fait que plus un peuplement est défolié, plus il y a de larves de la TBE et ainsi plus de papillons qui se retrouveront un jour ou l’autre sur les lacs à proximité et sédimenteront. Comme la TBE est toujours présente dans les forêts canadiennes, il a été impossible de différencier statistiquement une période endémique, donc sans défoliation, au tout début d’une épidémie. Les résultats ont également démontré qu'il n'existe aucune différence significative quant à l’endroit où les trappes à sédiments étaient positionnées dans les lacs. Le même résultat a été observé entre les valeurs du NDVI des peuplements forestiers et le nombre d’écailles de le TBE retrouvées dans les sédiments lacustres. Ce dernier est attribuable à la présence de coupe partielle qui a faussé les résultats à ce niveau. Ces résultats viennent donc renforcer le fort potentiel des écailles du papillon de la TBE en tant que paléo-indicateur
Changes induced by the containment measures of the first COVID-19 wave: a scoping review on work-family balance regarding working parents
Get PDFIn March 2020, COVID-19 was declared a worldwide pandemic. To limit its spread, governments and institutions have implemented drastic measures with major repercussions on the labor market, workers, and their families. Business, school, and daycare closures, as well as telework and home-schooling, have challenged working parents. In this unique context, researchers have examined COVID-19’s effects on work and family. Using the PRISMA-ScR guidelines, this scoping review explores, classifies, synthesizes, and analyzes the research findings from the first wave of the COVID-19 pandemic on work-family balance issues. More specifically, it examines how contextual forces hindered or facilitated working parents’ time management and work-family balance, along with coping strategies they implemented. Searches were conducted in 18 databases to identify relevant French or English peer-reviewed empirical articles published before April 2021. Articles should include information on parent workers at the first wave of the pandemic. Of the 570 papers identified, 56 were retained and synthesized. The articles cover worldwide populations, with one-quarter from the USA. Based on the Decision-action model, a thematic analysis allows identifying how the experience of the early months of the pandemic affects the life course of working parents and the work-family balance project considering the contextual forces to which they were exposed, and the strategies deployed to meet their needs. Findings reveal the fragility of the work-family balance among working parents and the disorganization caused by a major social crisis. They also highlight the importance of individual, organizational and governmental strategies to better support workers, families, businesses and communities
Cumulative interpersonal childhood adversity and post-traumatic stress symptoms across heterosexual, cisgender and gender and sexually diverse adolescents: The mediating role of emotion regulation
Get PDFBackground
Emotion regulation has been identified as an explanatory factor in the association between interpersonal childhood adversity and post-traumatic stress symptoms (PTSS). However, most studies focused on adults or older adolescents, neglecting youth from the community, especially gender and sexually diverse (GSD) adolescents, who have a higher risk for exposure to adverse events and psychological difficulties, compared to their heterosexual, cisgender (HC) peers.
Objective
The present cross-sectional study aimed to examine the mediating role of emotion regulation difficulties in the association between cumulative interpersonal childhood adversity and PTSS across HC and GSD adolescents.
Methods
A sample of 2904 ninth grade students (Mage = 14.53, SD = 0.61) completed a self-report survey. Multigroup path analyses were conducted to examine the proposed mediation model in all groups, and comparisons were made using chi-square difference tests.
Results
Greater difficulties in emotion regulation mediated the association between greater cumulative interpersonal childhood adversity (β = 0.36, p < .001) and greater PTSS (β = 0.35, p < .001) – regardless of HC or GSD status – although the direct association between cumulative interpersonal childhood adversity and PTSS was significantly stronger among GSD boys (β = 0.36, p < .001) and GSD girls (β = 0.35, p < .001) than among HC boys (β = 0.21, p < .001) and HC girls (β = 0.25, p < .001).
Conclusions
Findings offer a modifiable target for prevention and/or intervention among middle adolescents, as emotion regulation difficulties may partially explain the presence of PTSS following cumulative interpersonal childhood adversity
Can shared micromobility programs reduce greenhouse gas emissions: Evidence from urban transportation big data
Get PDFShared micromobillity has been extensively developed globally in the past few decades, but its impact on the environment remains unclear. This study quantitatively estimates the effects of global shared micromobillity programs on greenhouse gas (GHG) emissions using a life cycle assessment (LCA) perspective. Specifically, it takes major countries and cities around the world as examples to empirically analyze the impact of station-based bike-sharing (SBBS), free-floating bike-sharing (FFBS), free-floating e-bike sharing (FFEBS), and free-floating e-scooter sharing (FFESS) programs on the GHG emissions of urban transportation. The results show that, with the exception of SBBS, the other shared micromobillity programs have not achieved desirable GHG emissions reduction benefits. Contrarily to subjective expectations, although the rapid progress of technology in recent years has promoted the vigorous development of shared micromobility, it has brought negative impacts on the GHG emissions rather than the positive benefits claimed by related promoters and operators. The overcommercialization and low utilization rate makes shared micromobility more likely to be an environmentally-unfriendly mode of transportation. In addition, the regional differences in mode choice, operational efficiency, fleet scale, and market potential of shared micromobility and the corresponding impacts on GHG emissions vary greatly. Therefore, authorities should formulate appropriate shared micromobility plans based on the current conditions and goals of the region. This empirical study helps to better understand the environmental impact of the global shared micromobility program and offers valuable references for improving urban sustainability
Nos enfants sous microscope. TDA/H, hauts potentiels, multi-dys & Cie : comment stopper l’épidémie de diagnostics, Emmanuelle Piquet et Alessandro Elia, Paris, Payot, coll. « Psychologie », 2021, 332 p.
Get PDFUn article de la revue Nouvelles perspectives en sciences sociales, diffusée par la plateforme Érudit
Cohesive strength and fracture toughness of atmospheric ice
Get PDFThis paper aims at defining key mechanical properties of atmospheric ice in order to improve the design of mechanical de-icing systems. Based on ice fracture mechanisms, the parameters of interest are the cohesive strength of the ice and its fracture toughness. An hybrid experimental/numerical vibrating method is used to measure those critical values. Parameters such as temperature and precipitation rate influence the ice density and ice samples are thus defined with respect to this parameter. First the cohesive strength of ice is measured over the entire range of ice density and a polynomial expression of the cohesive strength of ice is given as a function of this density. Then the fracture toughness is measured for a smaller range of density and an average critical value is given. Finally, the influence of the properties computed are discussed to assess the conditions of atmospheric ice mechanical removal and the challenges for the design of mechanical ice protection systems. The study tends to show that as its density decreases, ice is more difficult to remove mechanically
An intelligent icephobic coating based on encapsulated phase change materials (PCM)
Get PDFThe phase change materials (PCMs) have attracted great interest for applications as smart icephobic coatings because of their capability to restore and release energy. PCMs release a large amount of energy as latent heat upon freezing, which is a stimuli-response behavior for anti-icing applications. Such materials embedded within coatings can be applied to exposed infrastructures to protect them against icing. Here, we encapsulated a mixture of PCMs in a urea–formaldehyde (UF) shell by in situ polymerization and then incorporated the microcapsules into a polydimethylsiloxane (PDMS) coating. Microcapsules 5–15 µm in diameter having a shell thickness of about 200 nm were fabricated. Investigating the chemical composition of the fabricated microcapsules confirmed that PCM material was successfully encapsulated within the UF shell. Moreover, the differential scanning calorimetry (DSC) analysis showed that the PCM preserved its phase-change characteristics when encapsulated and embedded within the matrix. Increasing the abundance of microcapsules within the coating lowered the ice nucleation temperature, verified by DSC, and increased the freezing-delay time because of PCM latent heat release. We utilized a custom-made apparatus, called micro-push-off set-up that allowed us to measure ice adhesion at the exact moment that the water droplet was completely frozen. Therefore, it was observed that the presence of the PCM microcapsules reduced ice adhesion strength, through either possible mechanism of the formation of quasi-liquid layer (QLL) or thermal expansion differences. Furthermore, lower ice adhesion resulted in reduced ice accumulation on the PCM-containing coatings, verified by the static accumulation test (SAT)
