Raman spectroscopy, a non-destructive solution to the study of glass and its alteration

This paper presents the potential of Raman spectroscopy, a non-destructive technique which can be applied in-situ, for the analyses of glass and their alteration. Recent analytical developments are summarised for different glass composition and practical examples are given. The paper describes how to extract compositional information from the glass, first based on the spectra profile to distinguish rapidly alkali silicate from alkaline-earth alkali silicate and lead alkali silicate glass, then using the spectral decomposition and correlations to extract quantitative data. For alkali silicate glasses, that are most prone to alteration, the spectral characteristics are described to interpret the alteration process (selective leaching or dissolution of the glass) from the Raman spectra of the altered glass. These developments have greatly widened the potential of the technique and supplement well its ability to measure the thickness of the altered layer and identify the crystalline deposits

Quantum key distribution session with 16-dimensional photonic states

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD.Comment: 8 pages, 3 figure

Social Capital and Educational Attainment: A Study of Undergraduates in a Faculty of Education

This research examines the effects of social capital on the development of knowledge, skills, and attitudes among a sample of undergraduate university students. A theoretical model containing 14 variables including university and social background, social capital, time management, and educational attainment is presented. The data obtained from questionnaires completed by 269 undergraduate students in the Faculty of Education at a western Canadian university are used to test the model. Structural equation modeling tests the relationships among the variables. The results indicate that when other variables are taken into account, students' perceptions of social capital resources have direct and indirect effects on their developing self-concepts and their educational achievement. Students' perceptions of support, specifically support derived from interactions with other students, are an important resource that relates positively to their academic self-concepts and their grades.Cette recherche étudie les effets du capital social sur le développement de connaissances, d'habiletés et d'attitudes d'un échantillon d'étudiants du premier cycle. Dans cet article, les auteurs présentent un modèle théorique compose de 14 variables dont la formation universitaire, le contexte social, le capital social, la gestion du temps et le niveau de connaissance. Ce modèle est mis à I’ épreuve par les résultats des questionnaires complétés par 269 étudiants du premier cycle à la faculté d'éducation d'une université dans l'Ouest du Canada. On a teste les rapports entre les variables par le biais de la modélisation par équation structurelle. Les résultats indiquent que, lorsqu'on tient compte d'autres variables, les perceptions qu'ont les étudiants des ressources de capital social agissent directement et indirectement sur le développement de leur concept de soi et sur leur niveau de connaissance. Les perceptions des étudiants sur l'appui, surtout celui découlant de leur contact avec d'autres étudiants, constituent une ressource importance qui a une influence positive sur leur concept de soi et sur leurs notes

Time Use and Educational Attainment: A Study of Undergraduate Students

This research examines the effects of students' time use in academically related activities and paid employment on their educational attainment. A theoretical model containing fourteen background, social psychological, time use, and educational attainment variables was formulated. The data were obtained from questionnaires administered to 308 undergraduate students in the Faculty of Education at a Western Canadian University. A stratified random cluster sampling procedure was used to select classes of students. Structural equation modelling is used to test the relationships among the variables. Results indicate that when other variables are taken into account, the time students spend in academically related activities and paid employment has little effect on their educational achievement and their educational expectations.Cette recherche examine les effets de la répartition du temps d'étude et du temps alloué à un emploi sur le succès académique des étudiants. Un modèle théorique comportant quatorze variables de type général, socio-psychologique, d'utilisation du temps, et portant sur les résultats de l'expérience éducative, a été développé. Les données ont été obtenues d'une enquête effectuée auprès de 308 étudiants non diplômés de la faculté d'éducation d'une université canadienne. Une méthode d'échantillonnage stratifié par groupe a été utilisée pour sélectionner les groupes-cibles d'étudiants. Une modélisation par équation structurale a été effectuée pour analyser les résultats. Ils indiquent, qu'une fois l'effet des autres variables pris en compte, le temps dédié aux activités académiques et à un emploi rémunéré a peu d'impact sur le succès académique des étudiants et sur leurs attentes en matière de formation