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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.
281

Top-down and bottom-up excursions beyond the standard model : the example of left-right symmetries in supersymmetry

Alloul, Adam 20 September 2013 (has links) (PDF)
The field of high-energy physics has been living a very exciting period of its history with the Large Hadron Collider (LHC) at CERN collecting data. Indeed, this enormous machine able to collide protons at a center of mass energy of 14 TeV promises to unveil the mystery around the physics at such energy scales. From the physicists side, the expectations are very strong as it isnowadays a certitude that the Standard Model of particle physics is incomplete and should, in fact, be interpreted as the effective theory of a more fundamental one. Unfortunately, the 7 and 8 TeV runs of the LHC did not provide any sign of new physics yet but there has been at least one major discovery in 2010, namely the discovery of a scalar particle with a mass of 125 GeV and whichproperties are very close to those of the Standard Model Higgs boson. Since then, many questions have come up as we now want to understand if it really is the Standard Model Higgs boson or if it exhibits any deviations. It is in this peculiar context that my research work was carried. In a first project, we, my supervisors, our collaborator and I, have wanted to explore thephenomenology associated with the neutralinos and charginos sector of the left-right symmetric supersymmetric model. Such an analysis can be motivated by several reasons such as the fact that the supersymmetric nature of these models provides a natural explanation for the infamous hierarchy problem, implies the unification of the gauge coupling constants at very high energy and provides a natural candidate for dark matter. In addition to these nice features, the left-right symmetry introduces a natural framework for explaining the smallness of neutrino masses but also helps in addressing several other unresolved issues in the Standard Model framework. Only focusing on the lightest charginos and neutralinos decaying into one or more light leptons, we have shown in our study that these models can be easily discovered in multi-leptonic final states as theylead to signatures very different from those induced by the Standard Model or its supersymmetric version.[...]
282

Advancing the Interhemispheric Switch Model of Perceptual Rivalry

Trung Thanh Ngo Unknown Date (has links)
Perceptual rivalry refers to visual phenomena that are characterised by alternations between different percepts, despite an unchanging sensory input. Two common types of perceptual rivalry are (i) reversible figures — two-dimensional stable images that when viewed, are perceived to switch between different interpretations, and (ii) binocular rivalry — the alternations in image dominance resulting from the presentation of conflicting stimuli, one to each eye. Several investigators have suggested that these rivalling phenomena are mediated by similar neural mechanisms. Such a view, however, has not only been inadequately substantiated, but has also yet to be assessed in the context of a directly testable neurophysiological model. Miller and Pettigrew have proposed a novel, high-level interhemispheric switch (IHS) explanatory model of binocular rivalry. This model conceptualises the perceptual alternations as being mediated by alternations between one hemisphere’s selected image and the other hemisphere’s selected (rival) image. To assess their hypothesis, caloric vestibular stimulation (CVS) was used. CVS is a simple, inexpensive, and non-invasive brain stimulation technique that unilaterally activates high-level attentional areas. In accordance with the IHS model, CVS was found to significantly affect predominance (the duration that one image is perceived relative to the other, within a given viewing period) during conventional binocular rivalry with horizontal/vertical gratings and with orthogonal oblique gratings. The present thesis therefore aims, through the use of CVS, to extend this IHS model of binocular rivalry to reversible-figure alternations and propose a general IHS model of perceptual rivalry. Chapter 1 provides a detailed literature review of the field within the context of comparing both perceptual rivalries. In Chapter 2, investigations are presented on two different reversible figures — the perspective-reversing Necker cube and the figure–ground reversing Rubin’s vase–faces illusion. In these experiments, CVS was found to significantly change observers’ predominance compared to their baseline predominance. These results demonstrate that interhemispheric switching also mediates the alternations of these visual phenomena, in addition to binocular rivalry, thereby extending the IHS model to one of perceptual rivalry in general. Moreover, the findings are interpreted in a cognitive neuroscience context, including a novel proposal of a forebrain framework for the IHS model. Chapter 3 presents CVS experiments that address the issue of percept–to–hemisphere selection and the reproducibility of CVS effects, following Miller’s initial work on two types of conventional binocular rivalry. In planned analyses, significant predominance changes were not found in horizontal/vertical rivalry, oblique rivalry and Necker-cube rivalry. In post-hoc analyses that accounted for study-design differences between Miller’s original experiments and the present experiment, CVS was again not shown to induce significant predominance changes in any of the rivalry types. Assessment of directional predominance changes following CVS appeared to suggest an arbitrary selection of percept–to–hemisphere in all rivalry types, although no firm conclusions could be drawn from the obtained data on this issue. Nevertheless, the experiments further extend upon Miller’s earlier work by examining the inter- and intra-individual reproducibility of CVS-induced effects on predominance. Such reproducibility was found to be low and potential reasons for this are discussed. The experiments in Chapter 4 examine a type of binocular rivalry in which dichoptic presentation of Díaz-Caneja stimuli yields rivalry among four different stable images: half-field rivalry between the images presented to the eyes, and coherence rivalry in which aspects of each eye’s presented image are perceptually regrouped into rivalling coherent images. Each of these rivalries was found to occur for about half the given viewing time. Furthermore, CVS significantly shifted the predominance of perceived coherent images (coherence rivalry) but not half-field images (eye rivalry). This finding suggests that coherence rivalry (like conventional rivalry according to previous experiments) is mediated by interhemispheric switching at a high level, while eye rivalry is mediated by intrahemispheric mechanisms, most likely at a low level. In addition, it is proposed that Díaz-Caneja stimuli induce ‘meta-rivalry’ whereby these discrete high- and low-level competitive processes themselves rival for visual consciousness. The current thesis thus presents a novel meta-rivalry model of multistable binocular rivalry. It also presents the first direct evidence that interhemispheric switching mediates reversible-figure alternations, thereby supporting a generalised IHS model of perceptual rivalry. It is argued that both models provide a parsimonious exploratory framework within which specific predictions can be made and readily tested. Finally, the findings of all experiments in the current thesis are summarised.
283

Advancing the Interhemispheric Switch Model of Perceptual Rivalry

Trung Thanh Ngo Unknown Date (has links)
Perceptual rivalry refers to visual phenomena that are characterised by alternations between different percepts, despite an unchanging sensory input. Two common types of perceptual rivalry are (i) reversible figures — two-dimensional stable images that when viewed, are perceived to switch between different interpretations, and (ii) binocular rivalry — the alternations in image dominance resulting from the presentation of conflicting stimuli, one to each eye. Several investigators have suggested that these rivalling phenomena are mediated by similar neural mechanisms. Such a view, however, has not only been inadequately substantiated, but has also yet to be assessed in the context of a directly testable neurophysiological model. Miller and Pettigrew have proposed a novel, high-level interhemispheric switch (IHS) explanatory model of binocular rivalry. This model conceptualises the perceptual alternations as being mediated by alternations between one hemisphere’s selected image and the other hemisphere’s selected (rival) image. To assess their hypothesis, caloric vestibular stimulation (CVS) was used. CVS is a simple, inexpensive, and non-invasive brain stimulation technique that unilaterally activates high-level attentional areas. In accordance with the IHS model, CVS was found to significantly affect predominance (the duration that one image is perceived relative to the other, within a given viewing period) during conventional binocular rivalry with horizontal/vertical gratings and with orthogonal oblique gratings. The present thesis therefore aims, through the use of CVS, to extend this IHS model of binocular rivalry to reversible-figure alternations and propose a general IHS model of perceptual rivalry. Chapter 1 provides a detailed literature review of the field within the context of comparing both perceptual rivalries. In Chapter 2, investigations are presented on two different reversible figures — the perspective-reversing Necker cube and the figure–ground reversing Rubin’s vase–faces illusion. In these experiments, CVS was found to significantly change observers’ predominance compared to their baseline predominance. These results demonstrate that interhemispheric switching also mediates the alternations of these visual phenomena, in addition to binocular rivalry, thereby extending the IHS model to one of perceptual rivalry in general. Moreover, the findings are interpreted in a cognitive neuroscience context, including a novel proposal of a forebrain framework for the IHS model. Chapter 3 presents CVS experiments that address the issue of percept–to–hemisphere selection and the reproducibility of CVS effects, following Miller’s initial work on two types of conventional binocular rivalry. In planned analyses, significant predominance changes were not found in horizontal/vertical rivalry, oblique rivalry and Necker-cube rivalry. In post-hoc analyses that accounted for study-design differences between Miller’s original experiments and the present experiment, CVS was again not shown to induce significant predominance changes in any of the rivalry types. Assessment of directional predominance changes following CVS appeared to suggest an arbitrary selection of percept–to–hemisphere in all rivalry types, although no firm conclusions could be drawn from the obtained data on this issue. Nevertheless, the experiments further extend upon Miller’s earlier work by examining the inter- and intra-individual reproducibility of CVS-induced effects on predominance. Such reproducibility was found to be low and potential reasons for this are discussed. The experiments in Chapter 4 examine a type of binocular rivalry in which dichoptic presentation of Díaz-Caneja stimuli yields rivalry among four different stable images: half-field rivalry between the images presented to the eyes, and coherence rivalry in which aspects of each eye’s presented image are perceptually regrouped into rivalling coherent images. Each of these rivalries was found to occur for about half the given viewing time. Furthermore, CVS significantly shifted the predominance of perceived coherent images (coherence rivalry) but not half-field images (eye rivalry). This finding suggests that coherence rivalry (like conventional rivalry according to previous experiments) is mediated by interhemispheric switching at a high level, while eye rivalry is mediated by intrahemispheric mechanisms, most likely at a low level. In addition, it is proposed that Díaz-Caneja stimuli induce ‘meta-rivalry’ whereby these discrete high- and low-level competitive processes themselves rival for visual consciousness. The current thesis thus presents a novel meta-rivalry model of multistable binocular rivalry. It also presents the first direct evidence that interhemispheric switching mediates reversible-figure alternations, thereby supporting a generalised IHS model of perceptual rivalry. It is argued that both models provide a parsimonious exploratory framework within which specific predictions can be made and readily tested. Finally, the findings of all experiments in the current thesis are summarised.
284

Listening comprehension in academic lectures : a focus on the role of discourse markers

Smit, Talita Christine 30 June 2006 (has links)
Increasing involvement with students at the University of Namibia has indicated their overall difficulty with comprehending and recalling information from oral content lectures. It has also been observed that in general very little attention is given to the development of listening skills in L2 ESP and EAP courses. For this study, I conducted a quasi-experiment to determine whether the recognition and interpretation of discourse markers will enhance students' listening comprehension in academic lectures. Students were tested to determine their comprehension of content information in a video-taped lecture. Qualitative data were collected by means of a questionnaire. After an intervention period of eight weeks, where the experimental group received strategy training in the recognition and interpretation of discourse markers in spoken texts, both groups were again tested. Their results were statistically compared. I also looked at related findings of other researchers. Finally, aspects for possible future research will also be considered. / English Studies / MA - (Specialisation in TESOL)
285

Desafios para a implementação da Base Nacional Comum Curricular

Nakad, Fabricio Abdo, Skaf, Gabriel Junqueira Pamplona 20 December 2017 (has links)
Submitted by Fabricio Abdo Nakad (fabricionakad@gmail.com) on 2018-01-15T12:53:15Z No. of bitstreams: 1 MPGPP_Dissertação_Fabricio_Gabriel.pdf: 812700 bytes, checksum: b776e6705ddee1e3798ce63fc6d39c7f (MD5) / Rejected by Mayara Costa de Sousa (mayara.sousa@fgv.br), reason: Prezados, Alguns itens deverão ser ajustados no trabalho: 1. A paginação começa na introdução, porém, todos os elementos pré-textuais devem ser contados. 2. Na folha de aprovação o "campo de conhecimento", "data" e "banca examinadora" devem estar inseridos à esquerda. 3. Esta faltando o abstract. Qualquer dúvida estou à disposição. Mayara 3799/3438 on 2018-01-16T22:52:04Z (GMT) / Submitted by Fabricio Abdo Nakad (fabricionakad@gmail.com) on 2018-01-17T18:37:20Z No. of bitstreams: 1 MPGPP_Dissertação_Fabricio_Gabriel.pdf: 1509698 bytes, checksum: 7614b8201ac3da3453ebb7931eb71f8e (MD5) / Approved for entry into archive by Mayara Costa de Sousa (mayara.sousa@fgv.br) on 2018-01-18T21:34:22Z (GMT) No. of bitstreams: 1 MPGPP_Dissertação_Fabricio_Gabriel.pdf: 1509698 bytes, checksum: 7614b8201ac3da3453ebb7931eb71f8e (MD5) / Made available in DSpace on 2018-01-19T17:28:02Z (GMT). No. of bitstreams: 1 MPGPP_Dissertação_Fabricio_Gabriel.pdf: 1509698 bytes, checksum: 7614b8201ac3da3453ebb7931eb71f8e (MD5) Previous issue date: 2017-12-20 / O presente trabalho foi realizado com o intuito de responder a pergunta “como fazer a Base Nacional Comum Curricular (BNCC) chegar nas salas de aula?”, tendo em vista os principais desafios relacionados ao processo de implementação do documento da Base, decorrentes, em grande parte, do fato de o Brasil ser um país de realidades socioeconômicas e costumes bastante díspares, além de o sistema de educação básica nacional ser constituído de uma rede extensa, distribuída por um território vasto e diverso. Foram levantados os principais modelos teóricos de implementação de políticas públicas, o contexto do tema no Brasil e o resultado prático em outros países que já adotaram uma base curricular comum. Buscou-se, em remate, propor soluções para viabilizar o processo de implementação da BNCC. / The present work was carried out with the purpose of answering the question “how to make the ‘Base Nacional Comum Curricular (BNCC)’ reach the classrooms?”, considering the main challenges related to the implementation process of the Base’s document, due, in large part, the fact that Brazil is a country with very different socioeconomic realities and mores, and the national basic education system consists of an extensive network, spread over a vast and diverse territory. Were analyzed the main theoretical models for the implementation of public policies, the context of the theme in Brazil and the practical result in other countries that have already adopted a common curricular basis. It was sought, in closing, to propose solutions to make viable the process of implementation of the BNCC.
286

Policy development and implementation in the post-liberalization era in Zambia (1990s and beyond): towards a participatory planning and economic management model

Mulungushi, James Shamilimo 03 1900 (has links)
This thesis investigates policy formulation and implementation processes in Zambia. A number of issues emerge with respect to the weaknesses of the system and how policy decisions worsened Zambia's economic performance instead of improving it. The Kaunda era policies of nationalization had an adverse impact on productivity of industries as well as affecting the resource flow from donors and business houses. On the other hand President Chiluba's reforms in the 1990s have had both positive and negative impacts on the people of Zambia. The rapid privatization and liberalization affected employment levels thereby worsening the poverty levels. Further, the liberalization brought in stiff competition from other countries forcing most manufacturing companies to close down. The policy environment based on the Bretton Woods Institutions seems not to be working as result of not taking into account the local Zambian situation. On the other hand, there were positive macroeconomic developments such as growth in GDP, lowering of inflation and stabilizing of exchange rates as from 1996. This has however not improved the living standards of the people. In Zambia, the shifts back and forth between strong and weak planning institutions have negatively affected policy development and implementation. There has been uncoordinated policy development; as a result, some policies in the major sectors are contradictory while in other cases policies are not linked to the resource envelope, making them un-implementable. Secondly, the institutional framework for policy development is not effective. There is generally lack of coordination among ministries, provinces and other stakeholders in planning, implementation and monitoring and evaluation of development programmes. This thesis urges that the improving planning capacities at the national, provincial and district levels should improve the processes of policy development and implementation in Zambia, which will in turn help to reduce poverty. Further, the districts should be the centre for the bottom-up process. In order to carryout this responsibility, efforts should be made to improve their capacities. As for the top-down process, the Sector Advisory Groups should continue to participate in the planning, monitoring and evaluation so as to contribute to policy formulation and implementation. These should be coordinated by the National Development Coordinating Committee (NDCC) through a Planning Bureau. / Development Studies / D. Litt. et Phil. (Development Studies)
287

On the Bottom-up Foundations of the Banking-Macro Nexus

Wäckerle, Manuel 06 November 2013 (has links) (PDF)
The complexity of credit-money is conceived as the central issue in the banking-macro nexus, which the author considers as a structural as well as process component of the evolving economy. This nexus is significant for the stability as well as the fragility of the economic system, because it connects the monetary with the real domain of economic production and consumption. The evolution of credit rules shapes economic networks between households, firms, banks, governments and central banks in space and time. The properties and characteristics of this evolutionary process are discussed in three sections. First, the author looks into the origins of the theory of money and its role for contemporary monetary economics. Second, he briefly discusses current theoretical foundations of top-down as well as bottom-up approaches to the banking-macro nexus, such as dynamic stochastic general equilibrium and agent-based models. In the third part he suggests an evolutionary framework, building on a generic rule-based approach, to arrive at standards for bottom-up foundations in agent-based macroeconomic models with a banking sector. (author's abstract)
288

Cognitive Abilities and their Influence on Speech-In-Noise Information Processing : a Study on Different Kinds of Speech Support and Their Relation to the Human Cognition / Kognitiva förmågor och deras influens på informationsbearbetning av tal-i-brus : en studie på olika typer av talstöd och deras relation till mänsklig kognition

Sjöström, Elin January 2017 (has links)
In this paper, top-down and bottom-up processing were studied regarding their effect on speech-in-noise. Three cognitive functions were also studied (divided attention, executive functioning, and semantic comprehension), and the effect they have on the speech processing and on each other. The research questions asked were if a difference in speech-in noise perception can be observed regarding the different levels of top-down and bottom-up support, if speech-in-noise is related to any of the researched cognitive abilities, and if there exists any correlation between these abilities. The method is a within-subject experimental design, consisting of four different tests: PASAT, to measure attention, LIT, to measure semantic comprehension, TMT, to measure executive functioning and SIN, to measure speech-in noise. The results showed a significant difference between top-down and bottom-up processing, a significant difference between top-down processing in decreasing and increasing conditions could also be seen. A negative correlation between the benefit of top-down support and the semantic comprehension task was found. Regarding the cognitive abilities a few correlations were found; the semantic comprehension task had a positive correlation to both the central executive task and the attentional task, the attentional task had a negative correlation to the central executive task, and both of the central executive subtasks had a positive correlation to each other. Most of the findings were expected, built on earlier cognitive hearing theories and studies.
289

Den internationella kontextens påverkan över en nations demokratiseringsprocess under transitionen från ett auktoritärt styre till ett demokratiskt  -  En analytisk kategorisering

Hassan, Alexander January 2009 (has links)
Abstract Bachelor thesis in political science by Alexander Hassan, autumn 2008, “Effects of external factors on a nations democratisation process during the transition from authoritarian to electoral democratic rule – A categorical analysis” Supervisor: Tomas Sedelius In recent years globalization has become a hot topic in understanding the world we live in today. Globalization has indeed had a great impact on international relations and with it a great influence on the domestic conditions that determine a nation’s possibilities. It is therefore rational to hold true that this also would apply to a nation’s democratic process. This basic notion is what lies as a foundation for the thesis, where the purpose of the study is to examine the relatively new field of the international context and its significance on democratisation. The aim of the study is to examine and determine, through a categorical analysis, the different forms and roles that the external factors can take during the process leading up to the transition and implementation of an electoral democracy, the most basic form of democracy. The thesis thus has demanded the study and infusion of all discourses within the field of democratisation processes, as the only way to produce the roles and forms of the international contexts impact on the domestic process is through the study and determination of the different domestic spheres associated with the process. The different forms of external influences have been studied within the confines of the third wave of democracy, and their roles in the democratic process determined depending on the respective domestic spheres they affect. The significant result of the studies where chiefly that all forms of external influence have the possibility to affect the democratisation process indirectly as well as directly. Where direct influence is exerted within the political sphere of the nation; where the actual transition takes place, and the indirect influence is exerted through the socio-economical and cultural sphere; which exerts its influence in the process through the political sphere.  The results thus show that it is hard to draw the conclusion that an indirect form of influence would be superior to the direct approach or vice versa, as both are prevalent in successful democratic transitions.
290

Mellan varumärke och gemensamt raster : Skilda sätt att se verksamhetsidéer för pedagogisk verksamhet / Between trademark and shared perspective : Different ways of seeing verksamhetsidé within the Swedish educational context

Thelin, Katina January 2013 (has links)
The aim of this study is to explore the ways in which verksamhetsidé is seen within the Swedish educational context. In Sweden, the concept verksamhetsidé is used for an idea or a set of ideas related to the practice of an organization, for instance a school or a school district. Although the importance of such shared ideas is often pointed out by practitioners as well as researchers within the field of school development, there is little consensus about their meaning. When it comes to questions about the actual function and character of such an idea, or set of ideas, little guidance is found in the literature. This thesis seeks to contribute to such knowledge. In order to describe variations in the ways such ideas are seen as well as in the ways working with such ideas are seen, a phenomenographic study was carried out. The empirical data consist of deep interviews with 14 school directors of education in one larger city in Sweden; each responsible for several schools and preschools in one district. As directors they were all involved in the process of developing a verksamhetsidé, to guide all educational activities in the area. Results suggest that verksamhetsidé can be seen as a trademark, as putty, as a compass, as a map, or as a shared perspective. Each of these conceptions is used as a label for a category of description, and together they constitute one of the study’s outcome spaces. When it comes to working with such ideas, another variation is found. This variation is described through the concepts of top-down implementation and bottom-up sensemaking. Moreover, the data suggest no correlation between a certain way of seeing a verksamhetsidé and a certain way of seeing how to work with it. / Människors sätt att se varierar. Samtidigt verkar det vara av betydelse att medarbetare i skolan och förskolan utvecklar gemensamma sätt att se åtminstone vissa aspekter av verksamheten. Att bygga upp och fördjupa förståelsen av en gemensam idé framställs i skolutvecklingsforskningen som en viktig aspekt av skolans och förskolans ledarskap. I den här avhandlingen beskrivs variationen i sättet att se verksamhetsidéer, och arbetet med sådana, som den framträder i en grupp skolchefer med övergripande ansvar för pedagogisk verksamhet. Variationen diskuteras sedan i relation till olika sätt att se skolutveckling och ledarskap, samtidigt som avsaknaden av koppling mellan specifika sätt att se verksamhetsidéer och specifika sätt att se arbete med sådana problematiseras. I den avslutande diskussionen framhålls särskilt betydelsen av att de som befinner sig i skolans eller förskolans praktik utvecklar kunskap om variationen och använder sig av den för att bygga upp ny kunskap med relevans för verksamheten och arbetet i den. Till grund för de resultat som presenteras ligger en intervjuundersökning genomförd i en större svensk stad, i vilken det vid tiden för studiens genomförande pågick ett arbete med att bygga upp en, för all pedagogisk verksamhet i staden, gemensam verksamhetsidé. / <p>The original ISBN number of this work ( 978-91-7063-520-5 ) has been replaced by a new one: 978-91-7063-571-7.</p>

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