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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.
561

Modèle de Littelmann pour cristaux géométriques, fonctions de Whittaker sur des groupes de Lie et mouvement brownien.

Chhaibi, Reda 24 January 2013 (has links) (PDF)
De façon générale, cette thèse s'intéresse aux liens entre théorie des représentations et probabilités. Elle se subdivise en principalement trois parties. Dans un premier volet plutôt algébrique, nous construisons un modèle de chemins pour les cristaux géométriques de Berenstein et Kazhdan, pour un groupe de Lie complexe semi-simple. Il s'agira pour l'essentiel de décrire la structure algébrique, ses morphismes naturels et ses paramétrisations. La théorie de la totale positivité y jouera un role particulièrement important. Ensuite, nous avons choisi d'anticiper sur les résultats probabilistes et d'exhiber une mesure canonique sur les cristaux géométriques. Celle-ci utilise comme ingrédients le superpotentiel de variété drapeau, et une mesure invariante sous les actions cristallines. La mesure image par l'application poids joue le role de mesure de Duistermaat-Heckman. Sa transformée de Laplace définit les fonctions de Whittaker, fournissant une formule intégrale particulièrement intéressante pour tous les groupes de Lie. Il apparait alors clairement que les fonctions de Whittaker sont aux cristaux géométriques, ce que les caractères sont aux cristaux combinatoires classiques. La règle de Littlewood-Richardson est aussi exposée. Enfin nous présentons l'approche probabiliste permettant de trouver la mesure canonique. Elle repose sur l'idée fondamentale que la mesure de Wiener induira la bonne mesure sur les structures algébriques du modèle de chemins. Dans une dernière partie, nous démontrons comment notre modèle géométrique dégénère en le modèle de Littelmann continu classique, pour retrouver des résultats connus. Par exemple, la mesure canonique sur un cristal géométrique de plus haut poids dégénère en une mesure uniforme sur un polytope, et retrouve les paramétrisations des cristaux continus.
562

Géométrie et dynamique sur les surfaces algébriques réelles

Moncet, Arnaud 20 June 2012 (has links) (PDF)
Cette thèse s'intéresse aux automorphismes des surfaces algébriques réelles, c'est-à-dire les transformations polynomiales admettant un inverse polynomial. La question centrale est de savoir si leur restriction au lieu réel reflète toute la richesse de la dynamique complexe. Celle-ci est traitée sous deux aspects : celui de l'entropie topologique et celui de l'ensemble de Fatou. Pour le premier point, on introduit une quantité purement géométrique, appelée concordance, qui ne dépend que de la surface. Puis on montre que le rapport des entropies réelle et complexe est relié à cette quantité. La concordance est calculée explicitement sur de nombreux exemples de surfaces, notamment les surfaces abéliennes qui sont traitées en détails, ainsi que certaines surfaces K3. Dans la seconde partie, on étudie l'ensemble de Fatou, qui correspond aux pointscomplexes pour lesquels la dynamique est simple. On montre, grâce à des résultats antérieurs de Dinh et Sibony sur les courants positifs fermés, que celui-ci est hyperbolique au sens de Kobayashi, quitte à lui enlever certaines courbes fixées par (unitéré de) notre transformation. Cette propriété permet d'en déduire que ce lieu réel ne peut pas être entièrement contenu dans l'ensemble de Fatou, hormis quelques cas exceptionnels où la topologie du lieu réel est simple et la dynamique bien comprise. Ainsi la complexité de la dynamique est presque toujours observable sur les points réels.
563

Exploring the relational qualities of older people in a residential care facility / Erika du Plessis

Du Plessis, Erika January 2013 (has links)
The social environment has been recognised as one of the key aspects in determining the quality of life throughout the human lifespan. Human behaviour, thoughts, feelings and attitudes are socially constructed and can only be understood when viewed from the perspective of social interaction. Older individuals, who live in residential facilities experience a diminished quality of life due to factors such as loss of independence, reduced social networks, functional dependence, and contextual changes. Depression, loneliness and social isolation are an integral part of these individuals’ lives. People develop specific styles of relating, also referred to as interpersonal styles. The systems theory is used to explain the circular processes of the interaction between people. In particular the Self-Interactional Group Theory (SIGT) is proposed as theoretical framework to explore the relational qualities of older people in a residential care facility. SIGT views the interaction between people on three levels, namely the intra-personal level, the interpersonal level and the group level, which operate interdependently in the interaction between people. The interpersonal level of analysis consists of the definition of the relationship, relational qualities, motivation to engage with people to address needs and needs satisfaction as well as the circular processes of which the interaction consists of. The interactions between people always take place in an interpersonal context, embedded in broader environments. A qualitative and exploratory research design was selected to explore the relational qualities in interactions between older individuals living in a residential care facility. This study is based on data collected during a primary research study at a residential care facility for older individuals in 2013. The purpose of study was to explore the quality of life of older individuals residing in a residential care facility in Gauteng, South Africa. The data-gathering process in the primary research study involved the Mmogo-Method, a visual projective data-gathering method, the World Café method and person-centred interviews to gain insight into the participants’ life experiences at the residential care facility. For the purpose of this research, only the person-centred interviews were used for the secondary analysis of the data. Twelve purposely-selected individuals (aged 80 to 95; 3 men and 9 women) from the residential care facility participated voluntarily in the person-centered interviews, which were audio recorded. The collected data were transcribed verbatim and subjected to two different methods of analyses. First, data were analysed thematically by adopting an inductive approach. The themes identified in this first phase were next subjected to a deductive content analysis. The themes were categorised according to the relational variables in accordance with the Interactional Pattern Analysis (IPA), thereby contributing to the trustworthiness of the findings. The findings revealed that the interactions between older individuals take place in a broader environment that advocate the active participation of people. Active participation takes place both in and outside the facility and older people reported that this contributed to their quality of life. The relational qualities that could be described as enhancing interpersonal connectivity and satisfying older people’s needs for confirmation were identified as empathy, unconditional acceptance of others, confirmation and interpersonal flexibility. This research, however, highlighted relational qualities that restrained quality of life of older people, namely confusing self-presentation, ineffective expression on needs and withdrawal due to physical immobility. Needs were expressed in a very unspecific, blaming or manipulative manner, and consequently needs were not satisfied, but provoked, instead, feelings of frustration, pain and guilt. This research highlighted the predicament that older people find themselves in. Their decreased physical abilities and limited emotional repertoire to move towards others and the environment also limit their needs satisfaction. The presenting problem of social isolation can be explained by the combination of limited physical mobility and relational qualities that restrain quality of life for older people. This research study thus holds important implications for relationship-focused approaches in residential facilities for older individuals in order to empower and enable them to enhance their quality of life. Specific recommendations include interventions to assist older people to express their needs more effectively and to use opportunities in interaction to confirm them as autonomous functioning older people. / MA (Psychology), North-West University, Potchefstroom Campus, 2014
564

Propriedades Vibracionais do Dipeptídeo L-Alanil-Alanina submetido a deformações homogêneas / Vibrational properties of the dipeptide L-Alanyl-Alanine submitted to homogeneous deformation

Silva, José Gláucio da January 2015 (has links)
SILVA, José Gláucio da. Propriedades Vibracionais do Dipeptídeo L-Alanil-Alanina submetido a deformações homogêneas. 2015. 131 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2015. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2016-03-18T16:45:00Z No. of bitstreams: 1 2015_tese_jgsilva.pdf: 4602304 bytes, checksum: c589f914ff64a0ac8fd63892133504ba (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2016-03-18T16:46:19Z (GMT) No. of bitstreams: 1 2015_tese_jgsilva.pdf: 4602304 bytes, checksum: c589f914ff64a0ac8fd63892133504ba (MD5) / Made available in DSpace on 2016-03-18T16:46:19Z (GMT). No. of bitstreams: 1 2015_tese_jgsilva.pdf: 4602304 bytes, checksum: c589f914ff64a0ac8fd63892133504ba (MD5) Previous issue date: 2015 / The dipeptide L-Alanyl – L-Alanine crystal was studied through polarized Raman scattering submitted to homogeneous deformations. The crystals were grown by slow evaporation technique from an aqueous supersaturated solution of the crystal powder. Rays-x diffractions measurements were realized to confirm a crystalline structure of the crystal. Polarized Raman scattering measurements were performed at room temperature, as well as the analysis of the group theory to the C4 factor group and a tentative assignment of the vibrational modes of crystal. Raman scattering measurements in the crystals as a function of temperature were realized between two intervals of temperature: first, at low temperature between 300 K and 11 K e 11 K and 300 K, and second, at high temperature between 300 K e 520 K and 520 K e 300 K, in the spectral range of 50 cm-1 to 3400 cm-1. From the results of low temperature measurements, it was possible to conclude that the crystal undergoes a second-order phase transition between 80 K and 60 K, from a tetragonal structure with C4 factor group to a monoclinic structure with C2 factor group, maintaining the same number of the molecules per primitive cell. The suggested mechanism to explain the phase transition is the occupation of non-equivalent sites by CH3 molecular groups present at Ala-Ala molecule. On the other hand, the crystal remained stable in the high temperature range studied, and the changes observed in the Raman spectra showed no evidence that the Ala-Ala crystal undergone phase transition or changes in molecule conformation. In those experiments were observed only quantitative changes in frequency and widths of the Raman modes, which are normal for any material subjected to variations in temperatures around 220 K. Raman scattering measurements in the crystals as a function of pressure in the pressure range between 0,1 GPa and 6,3 GPa, in compression and of 6,3 GPa and 0,1 GPa, in decompression, in the spectral region between 100 cm-1 and 3400 cm-1 showed two ranges where several qualitative changes occurred; the first, in low pressure interval between 1.7 GPa and 2.3 GPa and the second, at high pressure interval, between 4.5 GPa and 4.9 GPa. Between 1.7 GPa and 2.3 GPa, it was observed qualitative changes as well as the disappearance of an external mode around of 130 cm-1 and the anomalous behavior of other external mode around of 110 cm-1 for pressures of the order of 1,7 GPa. These qualitative changes suggest that the crystal exhibits a second order structural phase transition. Qualitative changes also were observed in others regions of the Raman spectrum through of special reorientation of the molecular groups CO2, CH3 and NH3. These qualitative changes characterize a structural second order phase transition. The mains qualitative changes observed between 4,5 GPa and 5,2 GPa were the disappearance of the external modes and the an large increasing of the width of the Raman modes, suggesting that the crystal exhibits a structural disorder in the crystalline structure when undergoes a phase transition for high pressures, possibly a amorphization. When performing decompression of the sample, the Raman spectrum returns to its initial form relative to pressure of 0,1 GPa indicating reversibility of phase transitions. / O cristal dipeptídeo L-Alanil-L-alanina (Ala-Ala) foi estudado através da técnica de espalhamento Raman polarizado submetido a deformações homogêneas. Os cristais foram crescidos pela técnica de evaporação lenta a partir de uma solução aquosa supersaturada do pó do cristal. Medidas de raios-x foram realizadas para confirmar a estrutura cristalina do cristal. Foram realizadas medidas de espalhamento Raman polarizado a temperatura ambiente, bem como análise da teoria de grupos para o grupo fator C4 juntamente com uma classificação exploratória dos modos normais de vibração do cristal. As medidas de espalhamento Raman foram realizadas em baixas temperaturas, entre 300 K e 11 K e 11 K e 300 K, e altas temperaturas, entre 300 K e 520 K e 520 K e 300 K, na região espectral de 50 a 3300 cm-1. Da análise dos resultados das medidas de baixas temperaturas foi possível concluir que o cristal exibe uma transição de fase de segunda ordem, entre 80 e 60 K, passando continuamente da estrutura tetragonal com grupo fator C4 para uma estrutura monoclínica com grupo fator C2 mantendo o mesmo número de moléculas na célula primitiva. O mecanismo proposto para explicar a transição de fase é a ocupação de sítios de simetria C1 não equivalentes pelos íons moleculares CH3 numa estrutura monoclínica pertencente ao grupo fator C2. O cristal manteve-se estável em todo o intervalo de alta temperatura estudado. Nestas experiências foram observadas apenas mudanças quantitativas nas frequências e larguras de linha dos modos Raman estudados, que é normal para qualquer material submetido a variações de temperaturas da ordem de 220 K. Medidas de espalhamento polarizado no cristal de Ala – Ala no intervalo de pressão entre 0,1 GPa e 6,3 GPa, na compressão, e de 6,3 GPa e 0,1 GPa, na descompressão, na região espectral de 100 cm-1 a 3400 cm-1 mostraram dois intervalos de pressão em que ocorrem diversas mudanças qualitativas; o primeiro entre 1,7 GPa e 2,3 GPa e o segundo entre 4,5 GPa e 4,9 GPa. Entre 1,7 GPa e 2,3 GPa foram observadas mudanças qualitativas significantes na região dos modos externos, tais como, o desaparecimento de um modo da rede em torno de 130 cm-1 e o comportamento anômalo de outro modo da rede em torno de 110 cm-1 para pressão de 1,7 GPa. Estas mudanças qualitativas sugerem que o cristal exibe uma transição de fase estrutural de segunda ordem. As outras regiões do espectro Raman do cristal apresentaram diversas mudanças qualitativas continuas no comportamento dos modos Raman das unidades que participam diretamente das pontes de hidrogênio, indicando que o cristal apresenta reorientações espaciais dos grupos moleculares CO2, CH3 e NH3. Estas mudanças qualitativas caracterizam uma transição de fase estrutural de segunda ordem. As principais mudanças qualitativas observadas entre 4,5 GPa e 5,2 GPa são o desaparecimento dos modos externos e, quantitativamente, um grande aumento na largura de linha dos modos Raman indicando que o cristal exibe uma desordem na estrutura cristalina durante a transição de fase de altas pressões, possivelmente uma amorfização. Na descompressão da amostra os espectros Raman são quase que totalmente recuperados na sua forma inicial indicando que o cristal apresenta transições de fase reversíveis.
565

Contando as simetrias rotacionais dos poliedros regulares

Monteiro, Guilherme Elias Egg 12 July 2013 (has links)
CAPES / Esta dissertação está dividida em duas partes. A primeira parte é uma introdução da teoria básica de grupos necessária para o desenvolvimento do teorema da órbita-estabilizador, que permite fazer as contagens das simetrias dos poliedros regulares. A segunda parte é a descrição de uma atividade aplicada em sala de aula. / This dissertation is divided in two parts. The first part is an introduction to basic group theory required for the development of the orbit-stabilizer theorem, that allows the counts of symmetries of the regular polyhedra. The second part is the description of an activity applied in classroom.
566

Contando as simetrias rotacionais dos poliedros regulares

Monteiro, Guilherme Elias Egg 12 July 2013 (has links)
CAPES / Esta dissertação está dividida em duas partes. A primeira parte é uma introdução da teoria básica de grupos necessária para o desenvolvimento do teorema da órbita-estabilizador, que permite fazer as contagens das simetrias dos poliedros regulares. A segunda parte é a descrição de uma atividade aplicada em sala de aula. / This dissertation is divided in two parts. The first part is an introduction to basic group theory required for the development of the orbit-stabilizer theorem, that allows the counts of symmetries of the regular polyhedra. The second part is the description of an activity applied in classroom.
567

Hyperbolicité et bouts des graphes de Schreier / Hyperbolicity and ends of Schreier graphs

Vonseel, Audrey 26 September 2017 (has links)
Cette thèse est consacrée à l'étude de la topologie à l'infini d'espaces généralisant les graphes de Schreier. Plus précisément, on considère le quotient X/H d'un espace métrique géodésique propre hyperbolique X par un groupe quasi-convexe-cocompact H d'isométries de X. On montre que ce quotient est un espace hyperbolique. Le résultat principal de cette thèse indique que le nombre de bouts de l'espace quotient X/H est déterminé par les classes d'équivalence sur une sphère de rayon explicitement calculable. Dans le cadre de la théorie des groupes, on montre que l'on peut construire explicitement des groupes et des sous-groupes pour lesquels il n'existe pas d'algorithme permettant de déterminer le nombre de bouts relatifs. Si le sous-groupe est quasi-convexe, on donne un algorithme permettant de calculer le nombre de bouts relatifs. / This thesis is devoted to the study of the topology at infinity of spaces generalizing Schreier graphs. More precisely, we consider the quotient X/H of a geodesic proper hyperbolic metric space X by a quasiconvex-cocompact group H of isometries of X. We show that this quotient is a hyperbolic space. The main result of the thesis indicates that the number of ends of the quotient space X/H is determined by equivalence classes on a sphere of computable radius. In the context of group theory, we show that one can construct explicitly groups and subgroups for which there are no algorithm to determine the number of relative ends. If the subgroup is quasiconvex, we give an algorithm to compute the number of relative ends.
568

Algebraic methods for constructing blur-invariant operators and their applications

Pedone, M. (Matteo) 09 August 2015 (has links)
Abstract Image acquisition devices are always subject to physical limitations that often manifest as distortions in the appearance of the captured image. The most common types of distortions can be divided into two categories: geometric and radiometric distortions. Examples of the latter ones are: changes in brightness, contrast, or illumination, sensor noise and blur. Since image blur can have many different causes, it is usually not convenient and also computationally expensive to develop ad hoc algorithms to correct each specific type of blur. Instead, it is often possible to extract a blur-invariant representation of the image, and utilize such information to make algorithms that are insensitive to blur. The work presented here mainly focuses on developing techniques for the extraction and the application of blur-invariant operators. This thesis contains several contributions. First, we propose a generalized framework based on group theory to constructively generate complete blur-invariants. We construct novel operators that are invariant to a large family of blurs occurring in real scenarios: namely, those blurs that can be modeled by a convolution with a point-spread function having rotational symmetry, or combined rotational and axial symmetry. A second important contribution is represented by the utilization of such operators to develop an algorithm for blur-invariant translational image registration. This algorithm is experimentally demonstrated to be more robust than other state-of-the-art registration techniques. The blur-invariant registration algorithm is then used as pre-processing steps to several restoration methods based on image fusion, like depth-of-field extension, and multi-channel blind deconvolution. All the described techniques are then re-interpreted as a particular instance of Wiener deconvolution filtering. Thus, the third main contribution is the generalization of the blur-invariants and the registration techniques to color images, by using respectively a representation of color images based on quaternions, and the quaternion Wiener filter. This leads to the development of a blur-and-noise-robust registration algorithm for color images. We observe experimentally a significant increase in performance in both color texture recognition, and in blurred color image registration. / Tiivistelmä Kuvauslaitteet ovat aina fyysisten olosuhteiden rajoittamia, mikä usein ilmenee tallennetun kuvan ilmiasun vääristyminä. Yleisimmät vääristymätyypit voidaan jakaa kahteen kategoriaan: geometrisiin ja radiometrisiin distortioihin. Jälkimmäisestä esimerkkejä ovat kirkkauden, kontrastin ja valon laadun muutokset sekä sensorin kohina ja kuvan sumeus. Koska kuvan sumeus voi johtua monista tekijöistä, yleensä ei ole tarkoitukseen sopivaa eikä laskennallisesti kannattavaa kehittää ad hoc algoritmeja erityyppisten sumeuksien korjaamiseen. Sitä vastoin on mahdollista erottaa kuvasta sumeuden invariantin edustuma ja käyttää tätä tietoa sumeudelle epäherkkien algoritmien tuottamiseen. Tässä väitöskirjassa keskitytään esittämään, millaisia eri tekniikoita voidaan käyttää sumeuden invarianttien operaattoreiden muodostamiseen ja sovellusten kehittämiseen. Tämä opinnäyte sisältää useammanlaista tieteellistä vaikuttavuutta. Ensiksi, väitöskirjassa esitellään ryhmäteoriaan perustuva yleinen viitekehys, jolla voidaan generoida sumeuden invariantteja. Konstruoimme uudentyyppisiä operaattoreita, jotka ovat monenlaiselle kuvaustilanteessa ilmenevälle sumeudelle invariantteja. Kyseessä ovat ne rotationaalisesti (ja/tai aksiaalisesti) symmetrisen sumeuden lajit, jotka voidaan mallintaa pistelähteen hajaantumisen funktion (PSF) konvoluutiolla. Toinen tämän väitöskirjan tärkeä tutkimuksellinen anti on esitettyjen sumeuden invarianttien operaattoreiden hyödyntäminen algoritmin kehittelyssä, joka on käytössä translatorisen kuvan rekisteröinnissä. Tällainen algoritmi on tässä tutkimuksessa osoitettu kokeellisesti johtavia kuvien rekisteröintitekniikoita robustimmaksi. Sumeuden invariantin rekisteröinnin algoritmia on käytetty esiprosessointina tässä tutkimuksessa useissa kuvien restaurointimenetelmissä, jotka perustuvat kuvan fuusioon, kuten syväterävyysaluelaajennus ja monikanavainen dekonvoluutio. Kaikki kuvatut tekniikat ovat lopulta uudelleen tulkittu erityistapauksena Wienerin dekonvoluution suodattimesta. Näin ollen tutkimuksen kolmas saavutus on sumeuden invarianttien ja rekisteröintiteknikoiden yleistäminen värikuviin käyttämällä värikuvien kvaternion edustumaa sekä Wienerin kvaternion suodatinta. Havaitsemme kokeellisesti merkittävän parannuksen sekä väritekstuurin tunnistuksessa että sumean kuvan rekisteröinnissä.
569

A Revisionist History of Loving Men: An Autoethnography and Community Research of Naming Sexual Abuse in Relationships

Ziegler, Lena M. 29 April 2021 (has links)
No description available.
570

Hur platt är platt? : En kvalitativ studie om icke-hierarkiska organisationer / How flat is flat? : A qualitative study of non-hierarchal organizations

Lundström Wittenfelt, Emma, Stedt, Lotten January 2023 (has links)
Syftet med denna studie är att förstå hur fenomenet platthet fungerar och upplevs i organisationer samt att få en ökad förståelse för självorganisering och formella och informella strukturer i icke-hierarkiska organisationer. En experimentell fenomenologisk studie gjordes på svenska platta organisationer med kriteriet få eller inga mellannivåer av chefer. Metoden som användes var en metodkombination där gruppintervjuer och djupintervjuer kombinerades. Totalt intervjuades åtta antal personer på företagen där en semistrukturerad intervjuguide användes som baserades på Jo Freemans essä The Tyranny of structurelessness från 1970. Det empiriska materialet kategoriserades senare genom en tematisk innehållsanalys och analyserades genom tre ansatser för att kunna identifiera och beskriva hur företagen var platta. Resultatet och analysen visade att de två företagen kunde anses vara platta på olika sätt. Andra fynd var att konceptet platt är komplext där olika faktorer samspelar med varandra. Vidare forskning bör fokusera på om det är organisationen som initierar platthet eller om rätt individer väljs in i en organisation och gör den platt. Vidare forskning kan också fokusera på intersektionalitet och hur identitet och makt samspelar i en platt organisation för att främja demokratisk deltagarmakt. / The purpose of this study is to understand how the phenomenon of flatness works and is experienced in organizations and to gain an increased understanding of self-organization and formal and informal structures in non-hierarchical organizations. An experimental phenomenological study was conducted on two flat organizations in Sweden with the criterion of few or no middle levels of managers. The method used was a method combination where group interviews and in-depth interviews were combined. A total of eight people were interviewed at the companies where a semi-structured interview guide based on Jo Freeman's essay The Tyranny of structurelessness from 1970 were used. The empirical material was later categorized through a thematic content analysis and analyzed through three approaches to be able to identify and describe how the companies were flat. The result and the analysis showed that the two companies could be considered flat in different ways. Other findings were that the concept flat is complex where different factors interact with each other. Further research should focus on whether it is the organization that initiates flatness or whether the right individuals are selected into an organization and make it flat. Further research can also focus on intersectionality and how identity and power interact in a flat organization to promote democratic participation.

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