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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Grappling with Patriarchies : Narrative Strategies of Resistance in Miriam Tlali's Writings

Cullhed, Christina January 2006 (has links)
This study is the first one devoted solely to the writings of the South African black novelist Miriam Tlali. It argues that her works constitute literary resistance not only to apartheid, noted by previous scholars, but also to South African patriarchies. Examining Tlali’s novels Muriel at Metropolitan (1975) and Amandla! (1980), and several short stories from Mihloti (1984) and Footprints in the Quag (1989), the study pits these texts against the black literary tradition dominated by men and also reads them within the social context of South African patriarchies, with its social restrictions on women and its taboos concerning sexualities. To distance herself from the patriarchal values inherent in the male literary tradition and to negotiate social and sexual restrictions on women, I argue, Tlali deploys narrative strategies like generic difference, generic dialogism, a double-voiced discourse, “whispering,” and “distancing.” Drawing on the theories of Mikhail Bakhtin and Julia Kristeva, this study first explores “novelistic” traits in Muriel which function both to resist male literary conventions, like the epic mode of narrative, and to criticise their patriarchal ideology. Second, relying on Bakhtin, it analyses the generic dialogism and double-voicedness in Amandla!. Finally, making use of Kristeva’s semiotics and her theory of sacrifice, the study traces the development of a sacrificial discourse of gendered violence from Amandla! to some of Tlali’s short stories. Supported by Martha J. Reinecke’s explication of Kristeva, I show that Tlali’s texts insist that gendered violence upholds the sacrificial economies of both patriarchal apartheid and African patriarchy. The strategies of “whispering” and “distancing,” I claim, surface in Tlali’s addressing of the sensitive issues of black women’s victimisation and gendered violence. “Whispering” entails muting the criticism of the perpetrators of gendered violence, whereas “distancing” results in dis/placing gendered violence on the margins of the community. This study also examines the literary/social context of Tlali’s oeuvre: it explores specific traits of the South African black literary tradition, how the issue of rape has been addressed there, and the depiction of African patriarchy in autobiographies by South African black women.
42

Electronic, Spin and Valley Transport in Two Dimensional Dirac Systems

January 2017 (has links)
abstract: This dissertation aims to study and understand relevant issues related to the electronic, spin and valley transport in two-dimensional Dirac systems for different given physical settings. In summary, four key findings are achieved. First, studying persistent currents in confined chaotic Dirac fermion systems with a ring geometry and an applied Aharonov-Bohm flux, unusual whispering-gallery modes with edge-dependent currents and spin polarization are identified. They can survive for highly asymmetric rings that host fully developed classical chaos. By sustaining robust persistent currents, these modes can be utilized to form a robust relativistic quantum two-level system. Second, the quantized topological edge states in confined massive Dirac fermion systems exhibiting a remarkable reverse Stark effect in response to an applied electric field, and an electrically or optically controllable spin switching behavior are uncovered. Third, novel wave scattering and transport in Dirac-like pseudospin-1 systems are reported. (a), for small scatterer size, a surprising revival resonant scattering with a peculiar boundary trapping by forming unusual vortices is uncovered. Intriguingly, it can persist in arbitrarily weak scatterer strength regime, which underlies a superscattering behavior beyond the conventional scenario. (b), for larger size, a perfect caustic phenomenon arises as a manifestation of the super-Klein tunneling effect. (c), in the far-field, an unexpected isotropic transport emerges at low energies. Fourth, a geometric valley Hall effect (gVHE) originated from fractional singular Berry flux is revealed. It is shown that gVHE possesses a nonlinear dependence on the Berry flux with asymmetrical resonance features and can be considerably enhanced by electrically controllable resonant valley skew scattering. With the gVHE, efficient valley filtering can arise and these phenomena are robust against thermal fluctuations and disorder averaging. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2017
43

Ressonadores de microdiscos com região ativa nanoestruturada bombeados por injeção eletrônica / Microdisk resonators with nanostructured active region pumped by electronic injection

Mialichi, José Roberto 17 August 2018 (has links)
Orientador: Newton Cesário Frateschi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-17T02:03:42Z (GMT). No. of bitstreams: 1 Mialichi_JoseRoberto_D.pdf: 4426656 bytes, checksum: f54944bc3408b22608afdd373e3445dd (MD5) Previous issue date: 2010 / Resumo: Esta tese de doutorado apresenta resultados experimentais do crescimento de pontos quânticos de InAs diretamente sobre InGaAsP de baixa energia de bandgap (?g=1420 nm), cujo desenvolvimento visa a obtenção de um meio ativo com emissão na banda C (1520¿1570 nm) para a fabricação de ressonadores de microdisco. Baseado em resultados de fotoluminescência e microscopia de força atômica, o fenômeno da inter-difusão de elementos na interface InAs/InGaAsP é proposto e calculado, indicando a presença de Gálio e Fósforo na composição dos pontos quânticos. O ganho óptico de pontos quânticos de InAs crescidos sobre InGaAsP é também calculado com base nos resultados obtidos na análise de inter-difusão. Subseqüentemente, a teoria dos modos ressonantes no microdisco, particularmente os modos chamados whispering gallery modes (WGMs), é desenvolvida com o intuito de auxiliar os cálculos de fator de qualidade, fator de confinamento e corrente de limiar. Uma estrutura multicamada (diodo PIN) com região ativa baseada em pontos quânticos do sistema InAs/InGaAsP foi crescida por epitaxia de feixe químico (CBE) para a fabricação de ressonadores de microdisco. A fabricação dos microdiscos é feita por litografia óptica, corrosão por plasma de íons e ataque químico seletivo de InP. Feixe de íons focalizados (FIB) foi usado para substituir o ataque por plasma para diminuir a rugosidade das paredes dos discos. Os ressonadores de microdiscos são caracterizados elétrica e opticamente e os resultados são confrontados com base nos resultados teóricos apresentados ao longo da tese. Com base nos resultados das caracterizações eletro/ópticas dos ressonadores, correções como a inclusão de perdas ópticas da rugosidade da borda e aquecimento local foram acrescidas ao modelo teórico, resultando em boa concordância com os resultados experimentais. Por fim, apresentamos o desenvolvimento de dispositivos híbridos a partir de polímeros orgânicos depositados diretamente sobre microdiscos de InGaAs com o objetivo de integrar meio ativo orgânico com ressonadores inorgânicos para aplicações em optoeletrônica. Estes resultados foram obtidos durante o programa de doutorado com estágio no exterior no Laboratório Nacional de Nanotecnologia (NNL) vinculado à Università del Salento (Lecce/Itália) / Abstract:This doctorate¿s thesis presents the growth of InAs quantum dots directly on high bandgap InGaAsP (?g=1420 nm) barriers to be used as the active region of microdisk resonators with emission in the C-band (1520¿1570 nm). Based on photoluminescence and atomic force microscopy experiments, the occurrence of inter-diffusion on the InAs/InGaAsP interface is calculated, suggesting the presence of Gallium and Phosphorus in the quantum dots (QDs) composition. Based also on the inter-diffusion results, the optical gain of the InAs QDs is calculated. Subsequently, microdisk resonator whispering gallery modes (WGMs) are calculated and employed to predicting the cavity quality and confinement factors, as well as the threshold current. A PIN diode with an active region based on InAs QDs was grown by Chemical Beam Epitaxy (CBE) for the fabrication of current injected microdisk resonators. Microdisk fabrication process is performed using photolithography, reactive ion etching and InP selective wet-etching. Focused ion beam is used to replace the plasma etching in order to reduce the roughness of the disk¿s edge. Microdisks resonators are characterized electrically and optically and the measurements are analyzed based on the theoretical results presented along this thesis. Based on these measurements, optical losses caused by disk¿s edge roughness and local heating are added to our simulation tool, resulting in better agreement with the experimental results. Finally, we present the development of hybrid resonators using organic polymer deposited directly on inorganic microdisks integrating an organic active medium with inorganic resonators for optoelectronic applications. These results were obtained during our work at the National Nanotechnology Laboratory (NNL) and the University of Salento (Lecce/Italy) / Doutorado / Física da Matéria Condensada / Doutor em Física
44

High Quality Rolled-Up Microstructures Enabled by Silicon Dry Release Technologies

Saggau, Christian Niclaas 24 August 2022 (has links)
Micro-technology relies on a highly parallel fabrication of 2D electronic and/or microelectromechanical devices, where in most cases silicon wafers are used as substrates. In contrast 3D fabrication shows unique advantages, such as footprint reduction or the possibility to obtain additional functionalities. For example, in the case of a sensor, knowledge of the acceleration in all possible directions, the surrounding electric or magnetic field among other quantities can help to determine the exact position of an object in 3D space. To do that it is crucial to retrieve all components of a vector field, which requires at least one out of plane component. In other fields like integrated optics three dimensional structures can enhance the coupling efficiency with free space interactions. As such 3D micro-structures will be crucial for upcoming products and devices. A highly parallel fabrication is required to enable mass-adaption, self-assembly is an emerging technology that could deliver this purpose. Examples of 3D structures created by self-assembly include polyhedrons like cubes, pyramids or micro tubular structures such as tubes or spirals. Following a self assembly scheme, 3D devices would be created through the fabrication of standard 2D structures that are reshaped through a self-assembly step into a 3D object. In this thesis a novel dry release protocol was developed to roll-up strained nanomembranes from a silicon sacrificial layer employing dry fluorine chemistry. This way a wet release is totally circumvented thus preventing damage of the created structures due to turbulent flow or capillary forces. Additionally the developed process enabled the use of standard CMOS deposition and processing tools, leading to a high increase in yield and quality, with yields exceeding 99% for microtubes. Building on the developed technology various devices where fabricated, for example rolled-up micro capacitors at a wafer scale with an increased yield and a low spread of electrical characteristics. For the E12 industrial standard more than 90% of devices behaved within the required performance characteristics. Furthermore the yield and Q-factor of roll-up whispering gallery mode resonators was strongly improved, making it possible to self assemble 3D coupled photonic molecules, which showed a mode splitting exceeding the FSR, as well as hybrid supermodes at points of energy degeneracy.:Contents Bibliographic Record i List of Abbreviations vii List of Chemical Substances ix 1 Introduction 1 1.1 Microelectromechanical Systems 1 1.2 Strain Engineering 2 1.3 Rolled - Up Nanotechnology 3 1.4 Objective and Structure of the Thesis 5 2 Materials and Methods 9 2.1 Fabrication Techniques 9 2.1.1 Substrates 9 2.1.2 Plasma Enhanced Chemical Vapor Deposition 9 2.1.3 Dry Etching12 2.1.4 Deep Reactive Ion Etching 18 2.1.5 Atomic Layer Deposition 19 2.1.6 Lithography 20 2.2 Characterization Techniques 22 2.2.1 Strain Measurement 22 2.2.2 Ellipsometry 23 3 Dry Roll-Up of Strained Nanomembranes 25 3.1 Rolled - Up Nanotechnology 25 3.2 Fabrication 26 3.2.1 Release 29 3.3 Conclusions 33 4 Rolled-UpMicro Capacitors 35 4.1 Micro Capacitors 35 4.2 Fabrication 38 4.3 Characterization 39 4.4 Conclusion 41 5 Optical Micro-Cavities 43 5.1 Optical Micro Cavities 43 5.2 Theorectical Background 45 5.2.1 Quality - factor 49 5.2.2 FDTD 52 6 Optical Microtube Resonators 55 6.1 Optical Whispering Gallery Mode Microtube Resonators 55 6.2 Fabrication 57 6.3 Active Characterization 60 6.4 Conclusions 64 7 Photonic Molecules 65 7.1 Coupled Photonic Systems 65 7.2 Fabrication 68 7.3 Device Characterization 71 7.4 Multimode Waveguides 84 7.5 Conclusions 85 8 Conclusions and Outlook 87 8.1 Conclusions 87 8.2 Outlook 88 Bibliography 91 List of Figures 109 List of Tables 117 A Equipment 119 Cover Pages 121 Selbstständigkeitserklärung 123 Acknowledgements 125 List of Publications 127 List of Presentations 129 Curriculum Vitae 131
45

The psychotherapeutic worth of horse whispering for the aggressive child

Bronkhorst, Karin 30 June 2006 (has links)
This dissertation employs a case study research design and reviews literature from the field of animal assisted therapy (AAT) with an emphasis on equine facilitated psychotherapy (EFP), as a possible therapeutic alternative for treating inappropriate aggressive behaviour in a young boy. The research suggests that Horse Whispering can indeed be regarded as a viable therapeutic technique when intent on breaking the aggressive behaviour cycle. / Educational Studies / M.Ed.
46

The psychotherapeutic worth of horse whispering for the aggressive child

Bronkhorst, Karin 30 June 2006 (has links)
This dissertation employs a case study research design and reviews literature from the field of animal assisted therapy (AAT) with an emphasis on equine facilitated psychotherapy (EFP), as a possible therapeutic alternative for treating inappropriate aggressive behaviour in a young boy. The research suggests that Horse Whispering can indeed be regarded as a viable therapeutic technique when intent on breaking the aggressive behaviour cycle. / Educational Studies / M.Ed.
47

Photon-plasmon coupling in optoplasmonic microtube cavities

Yin, Yin 27 March 2018 (has links)
Optoplasmonic microtube cavities, the combination of dielectric microcavities and noble metal layers, allow for the interactions between photonic modes and surface plasmons, leading to several novel phenomena and promising applications. In this thesis, the hybrid modes with different plasmon-types of evanescent field in the optoplasmonic microtube cavities are discussed. The basic physical mechanism for the generation of plasmon-type field is comprehensively investigated based on an effective potential approach. In particular, when the cavity wall becomes ultra-thin, the plasmon-type field can be greatly enhanced, and the hybrid modes are identified as strong photon-plasmon hybrid modes which are experimentally demonstrated in the metal-coated rolled-up microtube cavities. By designing a metal nanocap onto microtube cavities, angle-dependent tuning of hybrid photon-plasmon modes are realized, in which TE and TM polarized modes exhibit inverse tuning trends due to the polarization match/mismatch. And a novel sensing scheme is proposed relying on the intensity ratio change of TE and TM modes instead of conventionally used mode shift. In addition, localized surface plasmon resonances coupled to resonant light is explored by designing a vertical metal nanogap on microtube cavities. Selective coupling of high-order axial modes is demonstrated depending on spatial-location of the metal nanogap. A modified quasi-potential well model based on perturbation theory is developed to explain the selective coupling mechanism. These researches systematically explore the design of optoplasmonic microtube cavities and the mechanism of photon-plasmon coupling therein, which provide a novel platform for the study of both fundamental and applied physics such as the enhanced light-matter interactions and label-free sensing.
48

Nouvelles architectures de composants photoniques par l'ingénierie du confinement électrique et optique / News architectures for photonic components using electric and optical confinement engineering

Lafleur, Gaël 05 December 2016 (has links)
Le confinement électrique et optique par oxydation des couches minces d'AlGaAs est une étape essentielle dans la réalisation des composants photoniques actifs et passifs dans la filière de matériaux GaAs. La recherche de performances ultimes sur ces composants nécessite une meilleure maîtrise du procédé d'oxydation ainsi qu'une meilleure connaissance des propriétés optiques de l'oxyde d'aluminium (AlOx). Dans cette perspective, j'ai d'abord réalisé une étude expérimentale de la vitesse d'oxydation des couches d'AlGaAs en fonction de la température du substrat, de la composition en gallium des couches étudiées, de la pression atmosphérique et de la géométrie des mesas considérés. Puis, j'ai établi un modèle anisotrope permettant une meilleure résolution spatiale et temporelle de la forme du front d'oxydation de l'AlAs. Enfin, j'ai exploité ce procédé pour réaliser des composants d'optique guidée notamment des micro-résonateurs puis réalisé des guides optiques à fente et caractérisé leurs performances optiques. / Optical and electrical confinement using Al(Ga)As layer oxidation is a key milestone in the fabrication of active and passive GaAs-based photonic components. To optimize those devices, through the control of the optical and electrical confinements, a better modelling of oxidation process and a better understanding of optical properties of aluminum oxide (AlOx) is required. One part of this work is focusing on a throughout experimental study of AlGaAs oxidation kinetics, where I studied different important parameters such as wafer temperature, gallium composition, atmospheric pressure and mesa geometry. Then, I developed a new predictive model taking into account the process anisotropy, thus allowing a better temporal and spatial of AlAs oxidation front evolution. Finally, I could exploit this technological process to realize whispering gallery mode microdisks as well as slot optical waveguides, and I have characterized this latter photonic devices.
49

Tlumočnická neutralita při tlumočení na vysoké úrovni. / The interpreter's neutrality during interpreting for high-level officials.

Shyianok, Krystsina January 2018 (has links)
(in English): The diploma thesis "The interpreter's neutrality when interpreting for high-level officials" is a theoretical and empirical work and consists of two parts. The theoretical part tries to look into the concepts of neutrality, impartiality and bias and to point out the multidimensional nature of interpreter's neutrality. It also provides an overview of existing approaches to interpreter's neutrality and highlights the essence of high-level interpreting. The empirical part is a research probe that maps how professional conference interpreters who interpret for high-level officials in the Czech Republic and the Russian Federation view the concept of absolute interpreter's neutrality. At the same time it inquires whether they sometimes face the absence of interpreter's neutrality. Lastly, it outlines factors that can influence interpreter's neutrality and examines possible impacts of neutrality absence on interpreting performance. The results of empirical part may become a springboard for further research in interpreter's neutrality.
50

Nonlinear dynamics of Kerr optical frequency combs / Dynamique non-linéaire des peignes de fréquences optiques de Kerr Nonlinear dynamics of Kerr optical frequency combs

Balakireva, Irina 09 December 2015 (has links)
La présente thèse est consacrée à l’étude des peignes optiques de Kerr dans les résonateurs àmodes de galerie, au sein desquels la lumière peut être excitée par pompage externe. L’effet Kerrexistant dans ces résonateurs engendre des modes latéraux équidistants (dans le domaine spectral)de part et d’autre du mode excité, c’est à dire un peigne de fréquence. Cette thèse est diviséeen trois chapitres. Le premier est dédié à l’introduction de la génération de ces peignes et leurapplications. Le deuxième chapitre présente l’analyse de l’équation de Lugiato-Lefever, décrivantde manière analytique le système, et conduit à la construction de deux diagrammes de bifurcationpour les dispersions normale et anomale. Ils sont tracés en fonction des deux seuls paramètresexpérimentalement contrôlables une fois le résonateur fabriqué : la puissance du laser et sondécalage de fréquence. Ces diagrammes indiquent les plages de paramètres pour lesquels une,deux, ou trois solutions existent ainsi que leur stabilité. Les simulations numériques renseignentle type exact de solution associée à chaque aire (notamment les solitons brillants et sombres, lesbreathers, les peignes optiques de Kerr de premier et deuxième ordre, et un régime chaotique) ; cesdiagrammes indiquent donc les paramètres du laser à choisir afin de générer la solution souhaitée.Le troisième chapitre est dédié aux peignes de Kerr optique secondaires, lignes additionnelles dansle domaine spectral générées entre les lignes du peigne principal. Ils apparaissent en dispersionanormale, lorsque la quantité de photon pompe excède un seuil dit de second ordre, qui a étédéterminé numériquement. / This thesis is dedicated to the study of the Kerr optical frequency combs in whispering gallery moderesonators, where the light can be excited by the extern pump. Due to the Kerr effect existing in theseresonators, the quasi-equidistant lines in the spectral domain are generated around the excited mode,that is the frequency comb. This thesis is devided in three chapters. The first one is dedicated to theintroduction of the Kerr comb generation and their applications.The second one presents the analysisof the Lugiato-Lefever equation used for the analytical study of the system, leading to the constructionof two bifurcation diagrams for the normal and anomalous dispersions. They are plotted for twoparameters, which can be controlled during experiments once the resonator has been fabricated,which are the pump power of the laser and its frequency detuning. These diagrams show the areas ofthe parameters for which one, two, or three solutions exist and their stability. The additional numericalsimulations show the exact type of the solution in each area (such as the bright and dark solitons,the breathers, the primary and secondary Kerr combs and chaotical regimes), finally these diagramsshow the parameters of the laser needed to be choosen for the generation of the desired solution.The third chapter is dedicated to the secondary Kerr combs, which are the additional lines generatedbetween the lines of the primary comb. They appear in the anomalous dispersion regime, when thequantity of the pump photons crosses the second-order threshold, which has been found numerically.

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