Les premiers effets de la pandémie de Covid-19 sur les journalistes du Québec

La pandémie de COVID-19 bouleverse le monde entier lorsqu’elle survient en mars 2020. C’est le début d’une couverture journalistique exceptionnelle où pendant des semaines, voire des mois, toutes les nouvelles portent exclusivement sur le nouveau coronavirus qui paralyse la planète. Les journalistes, qui composaient déjà avec la crise financière des médias, sont alors confrontés à un flux d’information exorbitant et au fléau de la désinformation qui prend une ampleur jamais vue jusqu’alors. À cela s’ajoutent les risques sanitaires auxquels les professionnels de l’information doivent s’adapter pour se protéger tout en poursuivant leur travail, à l’heure où le grand public cherche par tous les moyens à s’informer. Ce mémoire est l’une des premières recherches universitaires à explorer la façon dont la pandémie de coronavirus affecte les journalistes du Québec dans la production de l’information. À partir de l’analyse de neuf entretiens semi-dirigés réalisés avec des journalistes qui ont couvert activement la pandémie, nous présentons comment ils se sont adaptés à de nouvelles contraintes qui ont menacé le droit à l’information. Nous abordons également leurs perceptions quant au double rôle qu’ils ont joué, celui de messagers et de chiens de garde du gouvernement. Enfin, nous présentons leur vision de l’importance de leur métier ainsi que leurs inquiétudes quant aux effets néfastes que la pandémie pourrait avoir sur l’avenir des médias d’information. Comme les journalistes jouent un rôle névralgique dans la communication de risques, qu’on appréhende d’autres vagues de COVID-19 et que d’autres crises sanitaires surviendront certainement, il importe de bien saisir les enjeux et défis avec lesquels les professionnels de l’information ont dû composer lors de cette pandémie mondiale. Ce mémoire établit la pertinence d’analyser le travail des professionnels de l’information et leur capacité à jouer pleinement leur rôle lors d’une prochaine crise sanitaire. De plus, il pointe vers des enjeux sur lesquels il faudra se pencher rapidement pour que les journalistes puissent continuer de réaliser leur travail.Abstract : The COVID-19 pandemic shook the world when it struck in March 2020. For weeks and even months thereafter, media coverage was all but consumed by the new coronavirus paralyzing the planet. Journalists, already in the throes of the financial crisis facing the media, were confronted with an unprecedented flow of information and a scourge of disinformation proliferating on a scale never seen before. Compounding this situation were the health risks to which news professionals had to adapt in order to protect themselves while continuing their work, at a time when the general public was seeking information by all available means. This thesis is one of the first academic research projects to explore how the coronavirus pandemic has affected Quebec journalists in their production of news. Based on an analysis of nine semi-structured interviews with journalists who actively covered the pandemic, the text presents how they have adapted to new constraints that have jeopardized the right to information. The thesis also addresses their perceptions of their dual role as messengers and as government watchdogs. Finally, it highlights their perspectives on the importance of their profession, as well as their concerns regarding the potential adverse impacts of the pandemic on the future of the news media. The vital role journalists play in risk communication, the anticipation of further waves of COVID-19, and the likelihood of subsequent health crises all point to the need to understand the issues and challenges faced by news professionals during this global pandemic. This thesis establishes the relevance of analyzing the work of news professionals and their ability to fully play their part in the context of future health crises, and underscores the issues that must be swiftly addressed if journalists are to be able to continue to do their work

Caractérisation et modélisation d'un élastomère dissipatif: application au pré-dimensionnement de pièces lamifiées élastomère-métal

National audienceDans cette communication, on présente des essais de caractérisation réalisés sur un caoutchouc chargé. A partir de ces résultats, nous proposons un nouveau modèle de comportement capable de traduire les effets de la fréquence et de l'amplitude du chargement. Par une approche phénoménologique et en se basant sur la thermodynamique des processus irréversibles, ce modèle est développé en grandes déformations et tient compte de la contrainte de faible compressibilité

Classification based on extensions of LS-PLS using logistic regression: application toclinical and multiple genomic data

International audiencePrediction from high-dimensional genomic data is an active field in today's medical research. Most of the proposed prediction methods make use of genomic data alone without considering established clinical data that often are available and known to have predictive value. Recent studies suggest that combining clinical and genomic information may improve predictions. We consider in this paper methods for classification purposes that simultaneously use both types of variables, but applying dimension reduction only to the high-dimensional genomic ones. A usual way to deal with that is the use of a two-step approach. In step one, dimensionality reduction technique is just performed on the genomic dataset. In step two, the selected genomic variables are merged with the clinical variables to build a classification model on the combined dataset. Nevertheless, the reduction dimension is built without taking into account the link between the response variable and the clinical data. To address this issue, using Partial Least Squares (PLS) as reduction technique, we propose here a one step approach based on three extensions of LS-PLS (LS for Least Squares) method for logistic regression context. We perform a simulation study to evaluate these approaches compared to methods using only the clinical data or only genetic data. Then, we illustrate their performances to classify two real data sets containing both clinical information and gene expression

Mechanical adhesion of SIO2 thin film on a polymeric substrate under compressive stress

International audienceTo ensure good adhesion between a 200 nm silicon dioxide layer and a 4.5 μm thick hardcoat polymeric coating, a better understanding of mechanisms of adhesion at this interface is needed. To reach this purpose, quantification of adhesion is performed by analyzing SiO2 buckle morphologies generated under compressive stress. This adhesion test was chosen for its representativeness of defects observed in real life. Interfacial toughness can be determined by applying Hutchinson & Suo model. This analytical model involves accurate value of elastic modulus Ef of SiO2 thin film. Small dimensions at stake make characterization of elastic modulus challenging. First part of the study focuses on using both nano-indentation and AFM to attempt assessment of SiO2 thin film elastic modulus. Results showed significant influence of substrate for both techniques. Impact on mechanical properties between SiO2 thin films with different intrinsic stresses was also investigated and suggests that higher density of SiO2 thin film leads to higher elastic modulus. Compression tests resulted in formation of straight-sided buckles that evolve into telephone cords upon unloading. Numerical simulation and Digital Image Correlation were implemented to ensure homogeneous strain of substrate and favor regular distribution of buckles. Values of energy release rates of SiO2 / Hardcoat range from 2.7 J/m² to 8.9 J/m², depending on moduli values found on wafer or lens substrate

FE simulation of interfacial delamination between SiO2 thin film and polymeric substrate

International audienceOphthalmic lenses are made of plastic polymeric substrates usually coated with functional treatments composed of 5 to 15 layers, ranging from micrometers to nanometers. Each of these interfaces may lead to delamination due to poor adhesion, and therefore affect the vision and comfort of wearers. The interface between the anti-reflective stack and the hardcoat is particularly sensitive because of chemical and mechanical contrast of its materials. To better understand mechanisms that lead to loss of adhesion between the SiO2 anti-reflective layer deposited on the anti-scratch hardcoat, compression experiments are performed to induce buckling of SiO2 layer. A Finite Element Model is developed to refine characterization of interfacial properties. Simulation of buckling phenomenon and delamination of SiO2 layer under compressive stress is proposed. Interfacial properties between SiO2 layer and hardcoat are modeled using cohesive elements following a traction separation law. Geometry of buckle yielded by the model is compared against experimental results to adjust the numerical model and access interfacial properties

Extension of the EM-algorithm using PLS to fit linear mixed effects models for high dimensional repeated data

International audienceIn studies where individuals contribute more than one observations, such as longitudinal or repeated measures studies, the linear mixed model provides a framework to take correlation between these observations into account. By introducing random effects, mixed models allow to take into account the variability of the response among the different individuals and the possible within-individual correlation. In addition, recent studies have collected high-dimensional data, which involve new statistical issue as the sample size is relatively small compared to the number of covariates. To deal with high dimensional data, reduction dimension method can be used which aims at summarizing the numerous predictors in form of a small number of new components (often linear combinations of the original predictors). The traditional approach is the Principal Component Regression which is an application of Principal Component Analysis (PCA) to regression model. PCA is applied without considering of the link between the outcome and the independent variables. An alternative method is the Partial Least Square (PLS) that takes this link into account. To solve the high-dimensional issue in the repeated/longitudinal data context, we propose an approach adapted from the Expectation-Maximization (EM) algorithm for linear mixed models by incorporating a PLS step to reduce the high-dimensional data to low-dimensional features. Under this algorithm framework, we use simulation studies to investigate the performance and computational properties of this extension of EM-algorithm using PLS (EM-PLS) and compare it with other reduction dimension approaches. To illustrate the practical usefulness of the approach, we apply the EM-PLS algorithm developed in this work to fit real data sets including for instance cell-cycle gene expression data observed over several time points or brain images collected during repeated sessions

Influence du quartier résidentiel et des problèmes de comportement extériorisés sur le rendement scolaire des adolescents

This study investigates if the socio-economic composition, as well as the physical and social disorder of neighbourhoods, were associated with academic performance among Quebec school children, with and without conduct problems, aged 12 to 15 (N = 630). In particular, the moderating role of conduct problems was explored. Findings indicated that physical and social disorder, along with the percentage of low-income individuals in the neighbourhood, were associated with some aspects of academic performance. Conduct problems did, however, moderate between neighbourhood variables and school performance. The implications of these findings will also be discussed.Cette étude vérifie si la composition et l’organisation sociale du quartier résidentiel sont associées au rendement scolaire d’élèves québécois âgés de 12 à 15 ans (N = 630). L’effet modérateur des problèmes de comportement extériorisés sur ces associations est aussi analysé. Les résultats montrent que le désordre physique et social du quartier ainsi que son niveau de désavantage socioéconomique sont associés à des aspects du rendement scolaire des élèves au-delà de leurs caractéristiques familiales et individuelles. La présence de problèmes de comportement chez les jeunes modère cependant certaines de ces associations. Ces résultats sont discutés en fonction des retombées pour la pratique

Understanding mechanisms of adhesion of SiO2 thin films evaporated on a polymeric substrate

A better understanding of mechanisms of adhesion between a 200 nm thick silicon dioxide layer and a 4.5 µm thick polymeric hardcoat is indispensable for an efficient adhesion at the interface. To reach this purpose, focus is placed on two axes: finding an applicable and effective method to quantify adhesion and in parallel, characterizing mechanical properties of materials composing the system. The second axis is needed to obtain data to feed modeling codes, enabling a better analysis of the adhesion experiment. Modulus of modified Si02 was found to be roughly 20% higher than reference Si02, by nanoindentation. AFM experiments showed no difference between modified and reference Si02• Currently, an investigation to detect cracks at the interface of interest for micro-tensile test is ongoing. Adhesion tests, such as micro-compression will be performed as well

Mechanical adhesion of SIO2 thin film on a polymeric substrate under compressive stress

To ensure good adhesion between a 200 nm silicon dioxide layer and a 4.5 μm thick hardcoat polymeric coating, a better understanding of mechanisms of adhesion at this interface is needed. To reach this purpose, quantification of adhesion is performed by analyzing SiO2 buckle morphologies generated under compressive stress. This adhesion test was chosen for its representativeness of defects observed in real life. Interfacial toughness can be determined by applying Hutchinson & Suo model. This analytical model involves accurate value of elastic modulus Ef of SiO2 thin film. Small dimensions at stake make characterization of elastic modulus challenging. First part of the study focuses on using both nano-indentation and AFM to attempt assessment of SiO2 thin film elastic modulus. Results showed significant influence of substrate for both techniques. Impact on mechanical properties between SiO2 thin films with different intrinsic stresses was also investigated and suggests that higher density of SiO2 thin film leads to higher elastic modulus. Compression tests resulted in formation of straight-sided buckles that evolve into telephone cords upon unloading. Numerical simulation and Digital Image Correlation were implemented to ensure homogeneous strain of substrate and favor regular distribution of buckles. Values of energy release rates of SiO2 / Hardcoat range from 2.7 J/m² to 8.9 J/m², depending on moduli values found on wafer or lens substrate