Propriétés optiques des nano-trous périodiques dans une couche mince métallique : modélisation, fabrication et application comme biocapteur

Dans cette thèse de doctorat, les réseaux de nano-trous périodiques dans des films métalliques sont étudiés. Leurs dimensions sont de l’ordre de la centaine de nanomètres, autant pour la taille du trou que l’espacement entre chacun et l’épaisseur du film. Ils possèdent des propriétés optiques remarquables : à certaines longueurs d’onde, la lumière qui diffracte à la surface de cette structure peut se coupler avec l’onde de propagation à l’intérieur du trou. Lorsque ces conditions sont rencontrées, un phénomène de résonance est excité et une forte transmission optique est observée de l’autre côté du film. On parle alors de transmission optique extraordinaire ou EOT pour "Extraordinary Optical Transmission". Le terme extraordinaire provient du fait que, si on considère la transmission optique des trous individuellement, l’intensité observée serait plusieurs ordres de grandeur inférieure à celle mesurée pour le réseau. De plus, même si on réunissait tout les trous en un seul grand trou (avec les proportions avec la partie métallique conservée), la transmission optique serait encore inférieure à celle observée pour le réseau. Le réseau possède donc la propriété de canaliser la lumière vers les indentations et ainsi de concentrer l’onde électromagnétique vers l’intérieur de l’indentation. Ces structures permettent de manipuler la lumière à l’échelle du nanomètre et ainsi de construire des matériaux avec des propriétés optiques remarquables. Dans une première partie de cette étude de ces structures, la modélisation des propriétés optiques est abordée en utilisant la théorie des modes couplés ou CMT pour "Coupled Mode Theory". Cette méthode consiste en une expansion des champs électromagnétiques des modes possibles dans chacun des milieux de la structure ainsi qu’un calcul des coefficients de couplages de l’onde d’un milieu à l’autre. Bien que d’autres méthodes de modélisation analytique existent, la CMT a été choisie car elle permet de minimiser les approximations employées dans la modélisation, tout en offrant un développement analytique typique des problèmes de transmission optique. De plus, sous certaines proximations, la méthode permet d’écrire les équations sous une forme simple qui décrit directement l’origine de la résonance. Une compréhension approfondie des mécanismes en jeu de la transmission optique est donc obtenue grâce à cette modélisation. Dans le cadre de ce travail de modélisation, une contribution originale a été effectuée afin d’approfondir la méthode lorsque l’on considère plusieurs modes possibles à l’intérieur des indentations.----------Abstract In this Ph.D thesis, periodic nanohole arrays built in metallic films are studied. These arrays consist in an arrangement of holes, spaced apart periodically, in thin metallic films. The structures are all of the order of the nanometer. These structures have extraordinary optical properties : for certain wavelengths, light can diffract at the surface of the metal and couple to the propagation wave inside the holes. When these conditions are met, a resonant phenomenon is excited and a strong transmission is observed. This phenomenon was termed extraordinary optical transmission or EOT. The term extraordinary comes from the fact that, if we consider the transmission of the sum of the isolated holes, the transmitted intensity would be orders of magnitude lower than the one observed from the array configuration. Furthermore, even if we were to assemble all the holes in one big hole (with hole/metal ratio conserved), the optical transmission would still be lower. These structure have the capacity to channel light inside the holes and concentrate electromagnetic radiation at the surface. They can thus manipulate light at the nanoscale level to create optical components with remarkable properties. In the first part of this thesis dedicated to the study of these structures, modelling of the optical properties of these structures is presented, using the method of Coupled Mode Theory (CMT). This method consists in an expansion of the electromagnetic fields in modes in the different regions of the structure and in a calculation of the coupling coefficients of the modes from one region to another. This method has several advantages compared to other methods, namely that is can minimize the approximations used, while offering an analytical development typical of problems in optics. Furthermore, under certain approximations, the method can describe the equations under a simple form which highlights the origin of the resonance. A deeper understanding of the mechanism involve in the resonance property of these structures can thus be achieved. One of the original contribution of this thesis was made in order to develop further the understanding of this method. Indeed, when considering the region inside the holes, most articles in the literature use only the fundamental mode. This approximation is good in the subwavelength case and for holes of small dimension, but becomes imprecise otherwise. Since the interesting dimensions of nanohole arrays for sensing might make use of all dimensions it was important to use a more complete model. A matrix formalism has thus been written in order to assess the contribution of each mode and the coupling of the modes between them

Health Care Workers' Risk Perceptions of Personal and Work Activities and Willingness to Report for Work During an Influenza Pandemic

The ability and willingness of health care workers to report for work during a pandemic are essential to pandemic response. The main contribution of this article is to examine the relationship between risk perception of personal and work activities and willingness to report for work during an influenza pandemic. Data were collected through a quantitative Web-based survey sent to health care workers on the island of Montreal. Respondents were asked about their perception of various risks to obtain index measures of risk perception. A multinomial logit model was applied for the probability estimations, and a factor analysis was conducted to compute risk perception indexes (scores). Risk perception associated with personal and work activities is a significant predictor of intended presence at work during an influenza pandemic. The average predicted probability of being at work during the worst scenario of an influenza pandemic is 46% for all workers in the sample, 36% for those overestimating risk in personal and work activities (95% CI: 35%-37%), 53% for those underestimating risk in work activities (95% CI: 52%-54%), and 49% for those underestimating risk of personal activities (95% CI: 48%-50%). When given an opportunity to change their intentions, 45% of those who initially did not intend to report for work in the worst scenario would do so if the pandemic resulted in a severe manpower shortage. These results have not been previously reported in the literature. Many organizational variables are also significant

Scoring methods in script concordance tests : an exploratory psychometric study

BACKGROUND:Despite the increasingly popular role of script concordance test (SCT) scoring methods in the evaluation of clinical reasoning, studies examining these methods in nursing are relatively scarce. This study explored the psychometric properties of five SCT scoring methods. METHOD:An SCT was administered to 12 experts and 43 learners. Scores were calculated using five methods and descriptive statistics. Differences in scores were assessed with the Mann-Whitney U test, and Spearman correlation coefficients were calculated for the different methods. RESULTS:The median scores of both experts and learners differed substantially according to the scoring method used. Learners' scores were statistically different from experts' scores (p < .01) for each method. Spearman coefficients (range, 0.44 to 0.95) were positive for the different methods. CONCLUSION:Further research is needed to refine the influence of SCT scoring methods for use in certifying assessment of clinical reasoning in nursing. [J Nurs Educ. 2023;62(10):549–555.

Assessment, Intervention, and Training Needs of Service Providers for Children with Intellectual Disabilities or Autism Spectrum Disorders and Concurrent Problem Behaviours

This study documented the perceived needs of therapists, specialists, and managers who work with children with intellectual disabilities (ID) and/or autism spectrum disorders (ASD) and concurrent problem behaviours (PBs). Seventy-five respondents from specialized PB and early childhood programs within eight public rehabilitation centres were surveyed. They were asked to describe current practices and perceived needs in terms of assessment, intervention, and training with respect to the target population. Overall, the perceptions of staff were consistent with the results of previous studies examining families’ perspectives. Salient themes include the need for specialized assessments for PBs in young children, collaboration between multiple service providers and families, and additional staff training in child development and interventions for PBs. These findings underscore the importance of offering diversified services adapted to the needs of children with PBs, their families, and their service providers

Measuring Muscle Mass and Strength in Obesity:A Review of Various Methods

Lower muscle mass in populations with obesity is associated obesity-related diseases like hypertension and type 2 diabetes mellitus. Bariatric surgery leads to sustained weight loss. During the weight reduction, loss of muscle should be minimized. Thus reliable quantification of muscle mass is much needed and therefore the also the need for validated methods. Imaging methods, magnetic resonance imaging and computed tomography scan, have been the gold standard for many years. However, these methods are costly and have limitations such as the maximum weight. Dual-energy X-ray absorptiometry is currently the most used alternative. Other, less expensive methods are very limited in their validation in populations with morbid obesity. This narrative review summarizes the current knowledge regarding measuring muscle mass and strength in obesity