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Strings, Branes and Non-trivial Space-timesBjörnsson, Jonas January 2008 (has links)
This thesis deals with different aspects of string and /p/-brane theories. One of the motivations for string theory is to unify the forces in nature and produce a quantum theory of gravity. /p/-branes and related objects arise in string theory and are related to a non-perturbative definition of the theory. The results of this thesis might help in understanding string theory better. The first part of the thesis introduces and discusses relevant topics for the second part of the thesis which consists of five papers. In the three first papers we develop and treat a perturbative approach to relativistic /p/-branes around stretched geometries. The unperturbed theory is described by a string- or particle-like theory. The theory is solved, within perturbation theory, by constructing successive canonical transformations which map the theory to the unperturbed one order by order. The result is used to define a quantum theory which requires for consistency d = 25 + p dimensions for the bosonic /p/-branes and d = 11 for the supermembrane. This is one of the first quantum results for extended objects beyond string theory and is a confirmation of the expectation of an eleven-dimensional quantum membrane. The two last papers deal with a gauged WZNW-approach to strings moving on non-trivial space-times. The groups used in the formulation of these models are connected to Hermitian symmetric spaces of non-compact type. We have found that the GKO-construction does not yield a unitary spectrum. We will show that there exists, however, a different approach, the BRST approach, which gives unitarity under certain conditions. This is the first example of a difference between the GKO- and BRST construction. This is one of the first proofs of unitarity of a string theory in a non-trivial non-compact space-time. Furthermore, new critical string theories in dimensions less then 26 or 10 is found for the bosonic and supersymmetric string, respectively.
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Modely hmoty v obecné relativitě s klesajícím počtem symetrií / Matter Models in General Relativity with a Decreasing Number of SymmetriesGürlebeck, Norman January 2011 (has links)
Title: Matter Models in General Relativity with a Decreasing Number of Sym- metries Author: Norman Gürlebeck Institute: Institute of theoretical physics Supervisor: Prof. RNDr. Jiří Bičák, DrSc., dr.h.c. Abstract: We investigate matter models with different symmetries in general relativity. Among these are thin (massive and massless) shells endowed with charge or dipole densities, dust distributions and rotating perfect fluid solutions. The electromagnetic sources we study are gravitating spherical symmetric condensers (including the implications of the energy conditions) and arbitrary gravitating shells endowed with a general test dipole distribution. For the latter the Israel formalism is extended to cover also general discontinuous tangential components of the electromagnetic test field, i.e., surface dipole densities. The formalism is applied to two examples and used to prove some general properties of dipole distributions. This is followed by a discussion of axially symmetric, stationary rigidly rotating dust with non-vanishing proper volume. The metric in the interior of such a configuration can be determined completely in terms of the mass density along the axis of rotation. The last matter models we consider are non-axially symmetric, stationary and rotating perfect fluid solutions. This is done with a...
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La relation entre les interactions positives avec l’enseignant et les pairs sur l'engagement affectif des élèves du primaire immigrants et non-immigrants en milieux défavorisésLamanque-Bélanger, Catherine 05 1900 (has links)
No description available.
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Approche didactique de l’éducation thérapeutique du patient diabétique à travers l’étude des conceptions des soignants et des patients : Analyse dans deux contextes socio-culturels différents : le département du Cher et le département de l'île de La Réunion / Didactic approach of the therapeutic education of the patient diabetic through the study of the conceptions of the caregivers and the patientsAuthier, David 03 December 2015 (has links)
Le traitement des maladies chroniques passe par plusieurs axes. L’un est technique et indispensable, issu de « l’évidence base médecine », il est biomédical et largement enseigné dans les facultés de médecine. L’autre est plus récent, moins présent dans les enseignements, et issu du « share decision making ». Ce dernier semble mieux considérer les valeurs du patient mais reste assujettie aux preuves biomédicales et investigations cliniques. L’abord du patient nécessite une interdépendance de ces deux approches et donc une part liée à l’éducation. La relation au patient se trouve modifiée par cette approche thérapeutique et impose au soignant un positionnement professionnel différent et requérant de nouvelles compétences. Il est intéressant de questionner au travers d’une étude menée dans deux milieux socio-culturels différents la possibilité d’un abord didactique des ateliers d’ETP. Cette approche, est menée dans un premier temps, par l’étude comparée des conceptions des patients et des soignants au cours de laquelle nous avons relevé des différences de conceptions non pas liées au macrocontexte mais plutôt au microcontexte et entre les soignants et les patients. Dans un deuxième temps, l’utilisation de concepts didactiques issus de la didactique des sciences, des travaux de Gérard Sensévy et de la littératie en santé va nous permettre de dégager des indicateurs et paramètres pouvant classer les différents types d’ateliers d’ETP et guider les soignants-formateurs au cours de leurs interventions éducatives. / Chronic illnesses can be treated along several axes.One of these is technical and indispensable, coming for the "evidence base medecine". It is biomedical and largely taught in medical schools. The other is more recent, less commonly taught and coming from "share decision making." The latter better considers the values of the patient but remains dependent on biomedical proof and chemical investigation. The patient approach requires an interdependence of the two approaches and is therefore, in part linked to education .The relation to the patient is modified by this therapeutic approach and requires and the caretaker to have a different professional position and requires new skills. It is interesting to question through a study lead in two different socio-cultural backgrounds the possibility of a didactic approach of the ETP workshops.Firstly, this approach, by the comparative study of conceptions of patients and caretakers during which we noticed different conceptions not only linked to the macro context but rather to the micro context between the two former.Secondly, the use of didactic concepts coming from the teaching of science from the works of Gérard Sensévy and the health literacy that allows us to identify the indicators and parameters.Allowing us to classify different types of ETP workshops and guide the care professionnal along their educational interventions.
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Hodnoty dětí a mládeže ze sociokulturně znevýhodňujícího prostředí (výzkumná sonda na ZŠ Chanov) / The values of children and young people from sociocultural disadvantaged backgrounds (research in elementary school Chanov)Fichtnerová, Miroslava January 2015 (has links)
This diploma thesis deals with the values of children and youth in the context of a sociocultural disadvantaged backgrounds. The work has theoretical and empirical character. The theoretical part explains the basic terminology and assumptions relating to values and value orientation, moral development of children, social exclusion. The text provides a detailed description of the Roma population including its history and current status, possible causes of problems and theoretical solutions psychosocial differences. Practical work provides data on socially excluded Roma locality Chanov and especially local elementary school. The research study provides an interpretation which life values Roma children perceive as important and what attitude to their value orientation have teachers of elementary school Chanov. The results of interviews and questionnaires are compared with the conclusions of the studies mentioned in the theoretical part.
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The Impact of Teacher Experience on the Achievement of Third-Grade Students in Inner-City SchoolsNewman, Rita Gray 08 1900 (has links)
This study investigated the impact of the years of teaching experience of classroom teachers on the achievement of third-grade students in inner-city Title I Schools; on the achievement of those third-grade students who were defined as high achievers, average achievers, and low achievers; and on the achievement of boys and girls in the third grade of inner-city Title I schools. An analysis and interpretation of the data revealed that there were no significant differences in reading and mathematics achievement of the third-grade students when the number of years of experience of the teacher was examined. Reading achievement of third-grade boys and third-grade girls did show significant differences. The more-experienced teacher appeared to have the greater increase in reading scores of the students. In addition to data concerning the hypotheses, information about other teacher variables was collected through a teacher self-report questionnaire. One hundred per cent of the teachers in the participating schools responded to the questionnaire. Data were tabulated by frequency of response in groups according to years of teacher experience. Variables included years of teaching experience in Title I schools, classroom size, and demographic data. Analysis of the data indicated that teachers having more years of experience in Title I schools appeared to have a greater increase in the reading and mathematics scores of students. Students in larger classes appeared to show greater gains than students in smaller classes in reading and mathematics. The majority of the teachers indicated that they felt the teacher, parent involvement, and class size had the most impact on achievement of students and staff development had the least impact.
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Community School Administrators’ Attitudes and Beliefs about Criminal Background Reviews During Enrollment ProcessesBrooks, Terrence J. 08 December 2022 (has links)
No description available.
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The Experiences of Refugee Students in United States Postsecondary EducationFelix, Vivienne R. 02 May 2016 (has links)
No description available.
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Teaching the Teachers: Reflections from two Graduate Teaching AssistantsGrimaldi, A., Selvaraj, M. Sudhir 29 January 2024 (has links)
Yes / This paper offers a critical reflection on the experience of two former Graduate Teaching Assistants (GTAs) - the authors - who were tasked with creating a digital learning program during the first UK national lockdown in 2020. The program drew from an emerging body of literature that seeks to employ Freirian pedagogies in the digital classroom and was designed to equip both new and established members of faculty with the skills needed for online teaching. While taking on this challenge, however, the experienced GTAs found that their pedagogical instincts and practices were challenged by their positionalities as young Early Career Researchers (ECRs) from underrepresented groups in British Academia. The aim of this paper is thus to scrutinise the potential for online learning to democratise and shift perceived hierarchies within academia, not only for students, but for ECRs navigating the structures of university teaching in the current employment climate.
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A detector for charged particle identification in the forward region of SuperB / Un détecteur pour l’identification des particules chargées dans la région avant de SuperBBurmistrov, Leonid 09 December 2011 (has links)
Dans cette thèse nous présentons la conception, l'étude des performances et les premiers tests, effectues au Cosmic Muon Telescope situe au SLAC, d'un nouveau détecteur d'identification des particules émises dans la région ''avant'' du détecteur SuperB.Ce détecteur est base une technique de temps de vol (TOF). Pour identifier les particules avec une impulsion jusqu'à 3GeV/c et une distance de vol de l'ordre de deux mètres nous avons besoin d'un détecteur TOF capable de mesurer le temps avec une précision typique de 30 ps. Pour atteindre cet objectif nous avons conçu un composant pour lequel le passage d'une particule chargée produit de la lumière Cherenkov dans un ''fused silica'' (quartz) radiator qui est ensuite détectée par des photodétecteurs tres rapides et une électronique rapide dédiée. Nous l'appelons détecteur DIRC-like TOF.Les photodétecteurs HAMAMATSU SL-10 MCP-PMT ont été caractérises sur faisceau de test au LAL et la résolution en temps d'environ 37 ps a été mesurée. La nouvelle électronique 16-canaux USB WaveCatcher développée au LAL(CNRS/IN2P3) et CEA/IRFU montre un jitter de moins de 10 ps. La géometrie du détecteur a quartz a été étudiée avec une attention particulière a l'aide d'une simulation Geant4. Celle-ci montre que la meilleure géométrie permet d'atteindre une résolution en temps d'environ 90 ps par photoélectron avec au moins 10 photoélectrons détectés, donnant en moyenne la résolution totale désirée de 30 ps.Nous avons construit un prototype d'un tel composant, utilisant les barres de quartz utilisées pour l'expérience Babar et nous l'avons installe dans le Cosmic Ray Telescope au SLAC. Une résolution en temps d'environ 70~ps par photoélectron a été obtenue, en accord avec la simulation.Cette preuve de principe a convaincu la Collaboration SuperB d'adopter un tel composant comme solution de base pour l'identification des particules émises vers l'avant dans SuperB. Le point délicat, encore ouvert, est celui de la résistance de ce détecteur aux bruits de fond de la machine.Dans cette thèse nous présentons aussi les études préliminaires de différents types de bruit de fond et leur effet sur les performances du détecteur DIRC-like TOF. Le processus Bhabha radiatif est de loin la source dominante de bruit de fond. Le taux de photoélectrons de bruit de fond principalement du aux gammas d'énergie d'environ 1.4 MeV est estimée a ~480 kHz/cm^2 ce qui correspond a 2 C/cm^2 de charge d'anode integrée sur 5 ans. Le flux de neutrons traversant l'électronique de front end du détecteur DIRC-like TOF est estimée a ~10^11/cm^2/year. Ces résultats préliminaires sont rassurants. / In this thesis, we present the conception, the performances studies and the first tests in the Cosmic Muon Telescope situated at SLAC of a new detector for the particle identification in the forward region of the SuperB detector.This detector is based on time-of-flight (TOF) technique. To identify the particles with momentum up to 3 GeV/c and flight base around two meters we need a TOF detector able to measure the time with a precision of about 30 ps. To achieve this goal we have conceived a device producing Cherenkov light in a fused silica (quartz) radiator, by a charged particle, which then detected with very fast photodetectors and dedicated ultrafast electronics. We call it, the DIRC-like TOF detector.For what concern the photodetectors, the HAMAMATSU SL-10 MCP-PMT has been characterized at LAL test bunch and the time resolution of about 37 ps has been measured. The new 16-channel USB WaveCatcher electronics developed by LAL (CNRS/IN2P3) and CEA/IRFU has shown to have a jitter of less than 10 ps. The geometry of the quartz detector has been then carefully studied with Geant4 simulation. Which shows that the best detector geometry allow to reach the time resolution of about 90 ps per photoelectron with at least 10 photoelectrons detected, giving in average the desired 30 ps total time resolution.We have constructed a prototype of such device, using the quartz bars available from the Babar experiment, and we have installed it, in the SLAC Cosmic Ray Telescope. A time resolution of about 70 ps per photoelectron was obtained, in agreement with simulation.This proof-of-principle has convinced the SuperB Collaboration to adopt such a device as the baseline for the SuperB particle identification detector in the forward region. The delicate point which is still opened is the resistance of this detector to the machine background.In this thesis we also present preliminary studies of different types of background and their effect on the performances of the DIRC-like TOF detector. Radiative Bhabha process is by far the dominant source of background. The rate of the background photoelectrons caused mainly by the gammas with energy around 1.4 MeV is estimated to be ~480 kHz/cm^2 which corresponds to 2 C/cm^2 of integrated anode charge in 5 years. The neutron flux thought the DIRC-like TOF front end electronics is ~10^11/cm^2/year. These preliminary results are reassuring.
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