Le système de types de la logique d'ordre supérieur permet d'exclure certaines expressions indésirables telles que l'application d'un prédicat à lui-même. Cependant, il ne suffit pas pour vérifier des critères plus complexes comme l'absence de divisions par zéro. Cette thèse est consacrée à l’étude d’une extension de la logique d’ordre supérieur appelée sous-typage par prédicats (predicate subtyping), dont l'objet est de rendre l'attribution de types aussi expressive que l'attribution de prédicats. A partir d'un type A et d'un prédicat P(x) de domaine A, le sous-typage par prédicats permet de construire un sous-type de A, noté {x : A | P(x)}, dont les éléments sont les termes t de type A tels que P(t) est démontrable. Le sous-typage par prédicats est au coeur du système PVS.Ce travail présente la formalisation d'un système minimal incluant le sous-typage par prédicats, appelé PVS-Core, ainsi qu'un système de certificats vérifiables pour PVS-Core. Ce deuxième système, appelé PVS-Cert, repose sur l'introduction de termes de preuves et de coercions explicites. PVS-Core et PVS-Cert sont munis d'une notion de conversion correspondant respectivement à l'égalité modulo beta et à l'égalité modulo beta et effacement des coercions, choisi pour établir une correspondance simple entre les deux systèmes.La construction de PVS-Cert est semblable à celle des PTS (Pure Type Systems) avec paires dépendantes et PVS-Cert peut être muni de la notion de beta-sigma-réduction utilisée au coeur de ces systèmes. L'un des principaux théorèmes démontré dans ce travail est la normalisation forte de la réduction sous-jacente à la conversion et de la beta-sigma-réduction. Ce théorème permet d'une part de construire un algorithme de vérification du typage (et des preuves) pour PVS-Cert et d'autre part de démontrer un résultat d'élimination des coupures, utilisé à son tour pour prouver plusieurs propriétés importantes des deux systèmes étudiés. Par ailleurs, il est également démontré que PVS-Cert est une extension conservative du PTS lambda-HOL, et qu'en conséquence PVS-Core est une extension conservative de la logique d'ordre supérieur.Une deuxième partie présente le prototype d'une instrumentation de PVS pour produire des certificats de preuve. Une troisième et dernière partie est consacrée à l'étude de liens entre logique classique et constructive avec la définition d'une traduction par double négation minimale ainsi que la présentation d'un algorithme de constructivisation automatique des preuves. / The type system of higher-order logic allows to exclude some unexpected expressions such as the application of a predicate to itself. However, it is not sufficient to verify more complex criteria such as the absence of divisions by zero. This thesis is dedicated to the study of an extension of higher-order logic, named predicate subtyping, whose purpose is to make the assignment of types as expressive as the assignment of predicates. Starting from a type A and a predicate P(x) of domain A, predicate subtyping allows to build a subtype of A, denoted {x : A | P(x)}, whose elements are the terms t of type A such that P(t) is provable. Predicate subtyping is at the heart of the proof system PVS.This work presents the formalization of a minimal system expressing predicate subtyping, named PVS-Core, as well as a system of verifiable certificates for PVS-Core. This second system, named PVS-Cert, is based on the introduction of proof terms and explicit coercions. PVS-Core and PVS-Cert are equipped with a notion of conversion corresponding respectively to equality modulo beta and to equality modulo beta and the erasure of coercions, chosen to establish a simple correspondence between the two systems.The construction of PVS-Cert is similar to that of PTSs (Pure Type Systems) with dependent pairs and PVS-Cert can be equipped with the notion of beta-sigma-reduction used at the core of these systems. One of the main theorems proved in this work is the strong normalization of both the reduction underlying the conversion and beta-sigma-reduction. This theorem allows, on the one hand, to build a type-checking (and proof-checking) algorithm for PVS-Cert and, on the other hand, to prove a cut elimination result, used in turn to prove important properties of the two studied systems. Furthermore, it is also proved that PVS-Cert is a conservative extension of the PTS lambda-HOL and that, as a consequence, PVS-Core is a conservative extension of higher-order logic.A second part presents the prototype of an instrumentation of PVS to generate proof certificates. A third and final part is dedicated to the study of links between classical and constructive logic, with the definition of a minimal double-negation translation as well as the presentation of an automated proof constructivization algorithm.

This study aims to analyse the impact of Social Media Marketing in Customer Brand Engagement and Brand Awareness micro-learning platforms. The sample consisted of 220 students from micro-learning platforms using social media in the educational institutions. Because social-media marketing and customer brand- engagement are second-order reflexive constructions, the two-stage approach of hierarchical models with mode-A was adopted. The results reveal that social media marketing influences both the building of customer brand engagement and brand awareness among students on micro-learning platforms. Furthermore, it was shown that customer brand engagement is an important mediator between social media marketing and brand awareness. Social-media marketing activities carried out by micro-learning platforms contribute to the generation of customer brand-engagement and brand awareness of these institutions. Furthermore, the results show that, although social-media marketing helps to generate brand-awareness, it is through customer brand-engagement that social-media marketing is most effective in generating brand-awareness. For micro-learning platforms, the results allow them to understand the importance of customer brand-engagement when using social-media marketing to generate brand-awareness.

Práce se zabývá buzením vyšších módů v kvádrových a válcových dielektrických rezonátorových anténách pro účely zvýšení zisku. Pomocí numerických simulací jsou studovány vlastnosti a limity anténních prvků. Je zkoumáná vzájemní vazba mezi dielektrickými rezonátorovými anténami pracujícími s vyššími vidy a na základě výsledků je možno usuzovat o vhodnosti těchto prvků k popužití v anténních řadách. V práci je popsán analytický model efektivní permitivity perforovaných dielektrik, který respektuje anizotropní povahu tohoto materiálu. Model je založen na Maxwell Garnettové aproximácií nehomogenních materiálů. Dále jsou studovány povrchové vlny na perforovaných substrátech a je ověřena použitelnost teoretického modelu i v tomto případě. Nakonec jsou studovány dielektrické rezonátorové antény vytvořené pomocí perforací v dielektrickém substrátu a je demonstrováno zhoršení určitých vlastností takových antén.

Cette étude concerne la caractérisation optique non linéaire (NL) principalement d’ordre 3 dans le visible, l’UV et l’IR en régime picoseconde de différents matériaux tels que certains solvants, le niobate de lithium et les nano-feuilles de graphène. Nous présentons d’abord les expressions des susceptibilités NL. Nous décrivons ensuite la technique de caractérisation Z-scan et ses variantes. Nous présentons une nouvelle méthode qui combine les avantages de Z-scan avec ceux de la microscopie en champ sombre. Nous montrons que cette technique d’imagerie, nommée DFZscan (Dark Field Z-scan), peut mesurer les coefficients de réfraction NL en présence d'une forte absorption NL. Les résultats expérimentaux montrent une importante amélioration de la sensibilité. Finalement, nous comparons les réponses NL des solvants les plus utilisés, dont l’eau qui possède la réfraction NL la plus faible. Ce liquide est utilisé pour caractériser la réponse NL d’une suspension de points quantiques de graphène. Grâce à un modèle simple, nous estimons l'indice de réfraction et d’absorption NL d'une nanofeuille de graphène monocouche. Nous étudions également les non linéarités d’ordres supérieurs dans les matériaux liquides (toluène) et solides (LiNbO3) en vue d’applications potentielles pour la génération de la deuxième harmonique et des modulateurs de guides d'ondes. Ces coefficients peuvent intéresser une grande communauté de chercheurs dans des domaines aussi variés que la filamentation, les solitons, le traitement tout optique du signal et les réseaux de télécommunications. / This study concerns the nonlinear (NL) optical characterization mainly of order 3 in the visible, UV and IR in the picosecond regime of different materials such as solvents, lithium niobate and graphene nanosheets. We first present the expressions of NL susceptibilities. We then describe the Z-scan characterization technique and its variants. We present a new method that combines the advantages of Z-scan with those of dark field microscopy. We show that this imaging technique, called DFZ-scan (Dark Field Z-scan), can measure NL refractive coefficients in the presence of high NL absorption. The experimental results show a significant improvement in the sensitivity. Finally, we compare the NL responses of the most commonly used solvents, including water with the lowest NL refraction. This liquid is used to characterize the NL response of a suspension of graphene quantum dots. Using a simple model, we estimate the refractive index and absorption index NL of a single-layer graphene nanosheet. We also studied higher order non-linearities in liquid (toluene) and solid (LiNbO3) materials for potential applications in second harmonic generation and waveguide modulators. These coefficients can be of interest to a large community of researchers in fields as diverse as filamentation, soliton, all-optical signal processing and telecommunications networks.

L’enseignant est, dans son exercice professionnel, guidé par des motivations personnelles qui se nourrissent de ses propres valeurs. Celles-ci se traduisent par des comportements, des discours et des attitudes et in fine, caractérisent un style pédagogique. Leur importance est relative et crée une hiérarchie pouvant être différente d’un enseignant à l’autre. Dès lors, se pose la question de savoir si certaines valeurs permettraient d’être davantage en bien-être au travail. Plus encore, le fait d’agir en cohérence par rapport à ses valeurs dans son enseignement serait-il un facteur propice à ce bien-être ?L’objectif de la thèse consiste à étudier les relations entre le bien-être au travail et les valeurs des enseignants d’Éducation Physique et Sportive (EPS).En s’inscrivant dans le cadre théorique des valeurs de base de la personne (Schwartz, 1992), un outil de mesure a été conçu pour examiner les valeurs des enseignants d’EPS dans le contexte particulier de l’enseignement de l’EPS avec 599 enseignants d’EPS. Ensuite, le travail a été mené en deux temps. En premier lieu, 396 enseignants d’EPS de l’académie de Lille ont complété un questionnaire permettant d’identifier leur système de valeurs général, leur système de valeurs opérationnalisé en EPS et leur niveau de bien-être subjectif au travail.Les résultats issus des analyses statistiques multifactorielles montrent que les valeurs sont déterminantes pour expliquer le bien-être au travail. Ainsi, ils révèlent que les valeurs d’ouverture au changement et de dépassement de soi sont plus vertueuses que les valeurs de continuité pour le bien-être des enseignants d’EPS. Si la nature des valeurs permet, en partie, d’expliquer le bien-être au travail, le fait d’agir en accord avec son système général de valeurs est un facteur plus déterminant. Ainsi, la concordance entre ses valeurs et ses pratiques professionnelles apparaît comme un objectif prioritaire pour améliorer le bien-être au travail. De plus, les résultats permettent d’identifier quatre profils caractéristiques d’enseignants selon leurs systèmes de valeurs et leur niveau de bien-être : les harmonieux, les compositeurs, les désaccordés et les sans-partitions.Parallèlement à ces enquêtes, douze entretiens semi-directifs ont été menés auprès d’enseignants d’EPS typiques des profils identifiés (trois par profil).Les résultats issus de l’analyse des entretiens permettent non seulement d’affiner la compréhension des profils d’enseignants d’EPS mais également de mieux comprendre le lien entre leurs systèmes de valeurs et leur niveau de bien-être au travail. Par ailleurs, les résultats révèlent que le partage de valeurs avec ses pairs est un facteur médiateur du bien-être au travail des enseignants d’EPS.En conclusion, ce travail de recherche basé sur une méthodologie mixte permet d’amorcer une réflexion pédagogique et didactique autour de l’importance des valeurs et de leur concordance dans l’enseignement. Il soulève également l’importance de clarifier collectivement les valeurs au sein des équipes pédagogiques. Une réflexion et un travail sur ces deux aspects devraient permettre d’améliorer le bien-être au travail des enseignants. / In their professional practice, personal motivation often guide teachers based on their personal values. These translate into behaviours, discourses, attitudes, and in fine, characterize a pedagogical style. Their importance is relative and creates a hierarchy that may differ from one teacher to another. In this thesis, we examine to what extent specific values may contribute to the increase of well-being at work. Also, is acting following one’s values while teaching a factor leading to well-being? The purpose of this thesis was to examine the relationship between values and well-being at work in Physical Education (PE) teachers.Within the theoretical framework of basic human values (Schwartz, 1992), one questionnaire was developed with 599 PE teachers to examine the professional values of french PE teachers in the area of PE teaching. Then the work was conducted in two steps.First, 396 PE teachers from Lille Academy completed a questionnaire to identify their profile of values, their values operationalized in PE, and their level of subjective well-being at work.Multifactorial statistical analyses show that values are a crucial variable to explain and predict well-being at work. Teachers scoring high in openness to change and self-transcendence higher-order values reported significantly higher well-being levels than those exhibiting high scores in conservation for PE teachers. One’s values are more determinant and significant. Concordance between values and professional practices should thus be an essential goal to reach in order to improve well-being at work.Besides, we identified four characteristic PE profiles according to their value systems and level of well-being: "harmonious," "composers," "detuned," and "without musical scores".Alongside these surveys, we conducted twelve semi-structured interviews with PE teachers taken from the profiles identified (three per profile).Analyses of the interviews helped to refine the understanding of PE teachers’ profiles and the link between their value systems and their level of well-being at work and confirms the findings of the questionnaire. Otherwise, they demonstrate that sharing values with their PE pedagogical team is a mediating factor for their well-being at work.In conclusion, this research, based on a mixed-method, allows starting a pedagogical and didactic reflection about the importance of values and their concordance in teaching. It also highlights the need to clarify collectively the values shared by the members of a pedagogical team. A reflection and work on both issues would improve teachers' well-being at work.

Digital educational technology is capable of contributing supplementary strategies that can be used to address various educational challenges faced by higher education. Foremost among these challenges is the widespread lack of academic preparedness of students who enter South African higher education institutions. The legacy of Apartheid, teachers' poor domain knowledge and command of the language of instruction, together with a lack of commitment to the cognitive development of learners are some of the reasons why students have not developed the cognitive skills required to engage in meaningful learning. Meaningful learning requires a high level of conceptual engagement and development. To assist in the learning process, educators must focus on student learning rather than on the instructor and the technology used in the instruction. A powerful means of supporting meaningful learning is through a process of model building. Computer technology can effectively be used to facilitate the building of conceptual models. By encouraging students to use computer technology to build models that represent their personal understanding, the students are performing the role of designer and the technology is used as a cognitive tool. Using digital technology as a cognitive tool allows students to engage in critical thinking and higher-order learning. An expert system shell is one way in which technology can be used as a cognitive tool. When students build expert systems they are required to demonstrate the reasoning of an expert and to exhibit an understanding of causal relationships and procedural knowledge. There is very little evidence of research concerning the application of expert systems as a cognitive tool in education. The primary aim of this study is to formulate design principles in the form of conjectures and principles related to a learning environment that uses technology as a cognitive tool in the form of an expert system shell to promote higher-order thinking skills. The second aim of this study is to explore the experiences of students who are exposed to a learning environment based on the conjectures and principles formulated during the design phase of the research. The conjectures and principles formulated during this study are expressed in terms of the characteristics, procedures and arguments associated with a learning environment that uses technology in the form of an expert system shell to facilitate higher-order thinking. These conjectures and principles were separated into seven interrelated clusters that can be summarised as follows: <ul><li> initial exposure;</li><li> guided discovery learning;</li><li> designing the expert system on paper;</li><li> creating domain awareness;</li><li> linking conceptual understanding to a representation of that understanding;</li><li> hands-on development; and</li><li> problem engagement.</il></ul> These conjectures and principles could guide similar endeavours undertaken by lecturers or instructional designers. / Thesis (PhD)--University of Pretoria, 2012. / Science, Mathematics and Technology Education / unrestricted

Tensors occur in many areas of science and engineering. Especially, they are used to describe charge, mass and energy transport (i.e. electrical conductivity tensor, diffusion tensor, thermal conduction tensor resp.) If the locale transport pattern is complicated, usual second order tensor representation is not sufficient. So far, there are no appropriate visualization methods for this case. We point out similarities of symmetric higher order tensors and spherical harmonics. A spherical harmonic representation is used to improve tensor glyphs. This paper unites the definition of streamlines and tensor lines and generalizes tensor lines to those applications where second order tensors representations fail. The algorithm is tested on the tractography problem in diffusion tensor magnetic resonance imaging (DT-MRI) and improved for this special application.

Newton's second law, Schrödinger's equation and Maxwell's equations are all theories composed of at most second-time derivatives. Indeed, it is not often we need to take the time derivative of the acceleration. So why are we not seeing more higher-order derivative theories? Although several studies present higher derivatives' usefulness in quadratic gravity and scalar-field theories, one will eventually encounter a problem. In 1850, the physicist Mikhail Ostrogradsky presented a theorem that stated that a non-degenerate Lagrangian composed of finite higher-order time derivatives results in a Hamiltonian unbounded from below. Explicitly, it was shown that the Hamiltonian of such a system includes linearity in physical momenta, often referred to as the ''Ostrogradsky ghost''. This thesis studies how one can avoid the Ostrogradsky ghost by considering degenerate Lagrangians to put constraints on the momenta. The study begins by showing the existence of the ghost and later cover the essential Hamiltonian formalism needed to conduct Hamiltonian constraint analyses of second-order time derivative systems, both single-variable and systems coupled to a regular one. Ultimately, the degenerate second-order Lagrangians successfully eliminate the Ostrogradsky ghost by generating secondary constraints restricting the physical momenta. Moreover, an outline of a Hamiltonian analysis of a general higher-order Lagrangian is presented at the end.

The SCANS report issued in 1990 brought national attention to concerns about lagging competencies of US workers and their lack of preparedness for the high-performance workplace. Since the SCANS report, several national and statewide efforts have attempted to identify skill sets appropriate for success in the changing workplace. Recent discussion has included skill sets appropriate for college graduates. This study was designed to determine perceptions of Maryland community college chief academic officers and department chairs toward one such skill set, the Maryland Skills for Success, and whether they are appropriate learning expectations for associate degree completers. The Maryland Skills for Success (MSS) are comprised of five skill goals: (1) learning skills, (2) thinking skills, (3) communication skills, (4) technology skills, and (5) interpersonal skills. Three to five 'learning expectations' elaborate what students should be able to accomplish under each skill goal to be successful in future work and learning. The study involved a survey of 293 chief academic officers and department chairs at the 18 community colleges across Maryland. A 75 percent response rate was achieved. The survey assessed the extent to which respondents agreed that: (a) the Maryland Skills for Success are appropriate expectations for associate degree completers, (b) students currently achieve MSS expectations, (c) respondent's courses and programs contain specific learning objectives that require students to learn and perform such skills, (d) all Maryland community colleges should teach and assess a common set of higher-order knowledge application skills. Respondent ratings indicated that the Maryland Skills for Success represent valid learning expectations for associate degree completers. Deans were more favorable toward the MSS than were department chairs, and were more confident that students were required to learn and perform learning expectations similar to those listed in the MSS. The department chairs were also divided into groups to determine attitudinal differences by disciplines. The department chairs were more likely than the deans to agree that students currently achieve the MSS learning expectations. Most chair groups somewhat disagreed their courses and programs contained specific learning objectives requiring students to learn and perform the skills represented in the MSS. Of the chair groups, the English/fine arts/humanities, and the technologies/health care groups tended to produce significantly higher ratings than other chairs and supported the notion of Maryland community Colleges teaching and assessing a common higher-order knowledge application skill set. Based on respondent ratings, the communication, thinking and interpersonal skill sets in the MSS have the best chance of gaining acceptance by colleges interested in integration of purposeful teaching and assessment of a higher-order skill set across the curricula. Respondent ratings also indicated that it is unlikely that the colleges would undertake a common initiative to teach and assess a common skill set like the MSS without intervention from the state. Respondents expressed distrust of bureaucratic intervention, were somewhat concerned about the difficulty of teaching and assessing the entire skill set, and felt that the skill sets were too broad to be feasibly taught. Recommendations include the need for extensive faculty development and the provision of incentives from the state educational agencies to provide support for colleges interested in teaching and assessing a common higher-order knowledge application skill set. / Ed. D.

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