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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.
81

Modificação de superfícies para o uso em cultura de células / Surface modification for use in cell culture

Araujo, Wagner Wlysses Rodrigues de 16 December 2014 (has links)
O projeto de novos materiais para aplicações tecnológicas em biomateriais e bioengenharia é altamente dependente de como as células aderem à superfície de um material. A adesão e crescimento em biomateriais depende de propriedades do substrato, tais como molhabilidade da superfície, a topografia e a composição química de superfície. O objetivo deste estudo foi investigar as interações de diversos materiais com culturas celulares de células epitelial CHO (Ovário de Hamster Chinês). Os materiais utilizados foram SU-8 2005 (elétron-resiste, Microchem), PDMS (Poli (dimetil siloxano), Down Corning), DLC (Diamond-like Carbon) e vidro foi utilizado como referência. Superfícies de vidro, SU-8, PDMS e DLC lisas (planas) e isentas de modificação ou tratamento específico foram avaliadas quanto ao cultivo de células CHO. Valores médios dos fatores de forma (Ff) de 450 células foram calculados para cada uma das culturas realizadas sobre os 4 substratos. Foram obtidos Ff próximos a 0,52 para o vidro, o SU-8 liso e o DLC, demonstrando um bom espraiamento das células nessas superfícies. A superfície de PDMS apresentou valor unitário para o fator de forma (Ff), que está relacionado a um baixo espraiamento das células. A energia de superfície (ES) obtida para o PDMS é compatível com o resultado de fator de forma (Ff), uma vez que o menor valor para ES é coerente com a baixa adesão celular, o que gerou células com elevado fator de forma (Ff). O SU-8 foi modificado por implantação iônica com uma dose de 1,2x1016 átomos/cm2 e a energia de implantação foi de 8 keV, como referência foi utilizada uma superfície lisa de SU-8 sem implantação. Os resultados mostraram que o número de células vivas por unidade de área foi superior na superfície de SU-8 com prata implantada, mostrando o bom desempenho da cultura nesse substrato. As superfícies de DLC modificadas por tratamento com plasma de oxigênio (DLC-O) e com plasma de hexafluoreto de enxofre (DLC-F) foram utilizadas para cultura celular, os resultados de três experimentos independentes de contagem de número de núcleos (marcados com DAPI) por unidade de área confirmaram os resultados obtidos através do teste de viabilidade (marcados com trypan blue). A superfície de DLC-O, apresentou um maior número de núcleos por unidade de área, quando comparado à superfície DLC-F, da mesma forma que nos resultados obtidos pelo teste de viabilidade. As energias de superfície para as amostras de DLC-F e DLC-O indicaram que a superfície DLC-O é mais hidrofílica do que a superfície DLC-F, que está coerente com o que é conhecido da literatura e com os resultados obtidos em nosso trabalho. Cultura de células CHO foram realizadas em superfícies litografadas com estruturas hexagonais periódicas com o parâmetro 2R (diâmetro do círculo inscrito) sendo 12 µm, 30 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. Estas superfícies foram caracterizadas por microscopia óptica de fluorescência com relação ao número de núcleos (marcados com o fluoróforo DAPI) por unidade de área, isto é, núcleos/mm2. Obteve-se histogramas com o número médio de núcleos por mm2 em três experimentos independentes, onde o número núcleos/mm2 foi consideravelmente maior para 80 µm. As superfícies contendo cavidades periódicas de 12 µm e 30 µm apresentaram dificuldade para as células CHO aderirem à superfície. Em uma outra etapa realizou-se culturas celulares em triplicata dos substratos com as superfícies 12 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. As células em cada uma das superfícies foram analisadas por microscopia óptica (MO) para avaliação da viabilidade celular, utilizando marcador trypan blue. Obteve-se histogramas com os valores médios para o número de células vivas/mm2 para as culturas celulares que corrobora os resultados obtidos no histograma da cultura celular que tiveram os núcleos marcados pelo fluoróforo DAPI. Assim, fica confirmado o melhor desempenho da cultura celular no substrato 80 µm que apresentou o maior número de células vivas/mm2 As micrografias obtidas através de marcação por DAPI foram analisadas através da função de correlação com intuito de se entender como as células estavam organizadas. Isso foi feito para cada uma das superfícies litografadas, 12 µm, 30 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. As superfícies dos substratos 80 µm apresentaram os menores valores de distâncias para primeiros e segundos vizinhos, ou seja, as células estão mais próximas umas das outras. As demais superfícies tendem a separar mais as células. Obteve-se também os valores de raio de aglomerado (rc), distância entre os aglomerados (dc) e o número de primeiros vizinhos (Np) através do ajuste da função de correlação. A análise de correlação mostrou com clareza o que não era evidenciado apenas visualizando-se as imagens. Ela mostra que as células, mesmo em SU-8 liso tem a forte tendência de formar aglomerados de células com raio de aproximadamente 45 µm. No caso de substratos lisos, células CHO apresentaram a melhor adesão na superfície do SU-8, seguido do DLC, enquanto que o PDMS foi a pior situação, devido à baixa molhabilidade do material. No caso de superfícies com microestrutura, SU-8 contendo microcavidades hexagonais de 12 e 30 µm mostraram ser as situações mais adversas para o crescimento de células CHO, provavelmente por causa da topografia das cavidades serem de menor tamanho quando comparadas ao tamanho das células CHO. Em vez disso, SU-8, contendo microcavidades hexagonais de 80 µm foi a superfície mais favorável para o crescimento de células CHO. / The design of new materials for technological applications in biomaterials and bioengineering is highly dependent on how the cells adhere to the material surface. The cells adhesion and growth on biomaterials depends on substrate properties such as surface wettability, topography and the chemical composition. The aim of this study was to investigate the interactions of various materials with cell cultures of epithelial cells CHO (Chinese Hamster Ovary). The materials used were SU-8 2005 (electron resists, Microchem), PDMS (poly (dimethyl siloxane), Dow Corning), DLC (Diamond-like Carbon) and glass was used as reference. Unmodified and flat surfaces of glass, SU-8, PDMS and DLC were evaluated for the culture of CHO cells. Form factor (Ff) values were calculated as average of 450 cells for each of the cultures performed on the four substrates. Ff close to 0.52 was obtained for flat surfaces of glass, SU-8 and DLC, showing a good cell spreading on these surfaces. The surface of PDMS presented a form factor (Ff) near unity, which is related to low spreading cell. The surface energy (ES) obtained for the PDMS is coherent with the Ff result, since the smallest value of ES is consistent with the low cell adhesion, which resulted in cells with a high Ff. The SU-8 was modified by ion implantation using a dose of 1.2x1016 atoms/cm2 and an implantation energy of 8 keV, unmodified flat SU-8 was used as a reference. The cell culture results showed that the number of live cells per unit area was greater in the SU-8 surface implanted with silver, showing a good performance in the culture substrate. The DLC surfaces modified by plasma treatment with oxygen (DLC-O) and sulfur hexafluoride (DLC-F) were used for cell culture. The results of three independent experiments, counting the number of nuclei (marked with DAPI) per unit area, confirmed the results obtained by the viability test (marked with trypan-blue). The surface of the DLC-O had higher number of nuclei per unit area when compared to the surface of the DLC-F, similarly to the results obtained for the viability test. The surface energies of the DLC-F and DLC-O samples indicated that the DLC-O surface is more hydrophilic than the DLC-F surface, which is consistent with results obtained with our work and with the literature. CHO cell culture were performed on surfaces with periodic hexagonal structures with the diameter of inscribed circle (2R) given by 12 µm, 30 µm, 80 µm, 280 µm, 560 µm and also on flat SU-8. These surfaces were characterized by fluorescence optical microscopy with respect to the number of nuclei (marked with fluorophore DAPI) per unit area, i.e. nuclei/mm2. Histograms were obtained for the average number of nuclei per mm2 in three independent experiments, where the substrate with periodic hexagonal structures with 2R = 80 µm presented considerably higher nuclei/mm2. Surfaces containing periodic cavities of 2R =12 µm and 30 µm were adverse for CHO cells adhesion. In another approach, cell culture were analyzed by light microscopy (LM) for evaluation of cell viability using trypan-blue marker. This was carried out in triplicate cell culture on substrates with surfaces 12 µm, 80 µm, 280 µm, 560 µm and also on flat SU-8. Histograms were generated for average number of living cells/mm2 for each substrate, which corroborates with the results obtained for the cell culture marked with fluorophore DAPI. Thus, it is confirmed the better performance of the cell culture on substrates with 2R = 80 µm, presenting the highest number of living cells/mm2. The micrographs obtained with cells marked with DAPI were analyzed through the correlation function with the aim of understanding how the cells were organized. This was performed for each of the lithographed surfaces 12 µm, 30 µm, 80 µm, 280 µm, 560 µm and also flat SU-8. The surfaces of the substrates with 2R = 80 µm had the lowest values for length between its neighbors, that is, the cells are closer to each other. The remaining surfaces tend to separate the cells. Also were obtained the cluster radius values (rc), the distance between the clusters (dc) and the number of nearest neighbors (Np) through the correlation function fitting. The correlation analysis clearly showed what was not possible to observe by viewing the images. It shows that the cells, even in flat SU-8, have a strong tendency to form clusters of cells within about 45 micrometers. In the case of flat substrates, CHO cells exhibited better adhesion to the surface of SU-8, followed by the DLC, while the PDMS was worse due to low wettability of the material. In the case of surfaces with microstructures, SU-8 containing hexagonal microstructures of 12 and 30 µm showed to be the most adverse conditions for the CHO cell growth, probably because of the topography of the cavities being smaller in size compared to the size of CHO cells. SU-8 with 80 µm hexagonal microstructures was more favorable surface for the growth of CHO cells.
82

Korporatyvinės komunikacijos taikymas ryšiuose su vietos bendruomene / Corporate communication practice in local community relations

Matijošiūtė, Agnė 25 November 2010 (has links)
Magistro darbo objektas – ryšių su bendruomene taikymo principai. Darbo tikslas – ištirti korporatyvinės komunikacijos taikymą ryšiuose su vietos bendruomene. Pagrindiniai darbo uždaviniai: išanalizuoti korporatyvinės komunikacijos sampratą ir jos reikšmę organizacijai; aptarti pagrindines korporatyvinės komunikacijos veiklas; atskleisti komunikacijos su bendruomene ypatumus; nustatyti ryšių su vietos bendruomene principus; išanalizuoti ryšių su bendruomene taikymą ir tendencijas Lietuvoje. Naudojantis mokslinės literatūros analizės, kokybiniu pusiau struktūruotu interviu ir stebėsenos metodais, prieita prie išvados, kad ryšiai su bendruomene yra viena pagrindinių korporatyvinės komunikacijos veiklų, todėl komunikacija su šia tiksline organizacijos auditorija turėtų būti paremta nuolatine abipuse komunikacija, dialogu, bendradarbiavimu ir nauda. Komunikacija su bendruomene turėtų prasidėti nuo auditorijos ištyrimo, kad būtų nustatytos jai aktualios problemos, bendradarbiavimo taškai. Komunikacijoje su bendruomene organizacija privalo būti atsakinga ir iniciatyvi bei palaikyti iniciatyvas, kylančias iš bendruomenės. Jos komunikacija turi būti skaidri, informatyvi, kryptinga ir tikslinga. Be to, visi veiksmai turėtų būti nukreipti į prioritetines bendruomenės sritis, nepamirštant ir organizacijos tikslų, t.y., remiantis strategija. Lietuvoje ryšiai su bendruomene nėra prioritetinė organizacijų strateginė veikla, be to, ši sritis gana vangiai vykdoma. Tačiau ryšiai su... [toliau žr. visą tekstą] / In the scientific world corporate communication is discussed in several respects. From one perspective corporate communication breaks down into three major activities: marketing, management and organizational. From other perspective, it assigns a number of other communication activities. Some theorists also distinguish the essential activities among which the most important and fundamental is described as relationship with the community. However, due to the lack of understanding of its benefits, communication with the local community in Lithuania is not sufficiently established. It was therefore important to take a comprehensive approach to the relationship with the community within the field of corporate communication and discuss the prospects of their application in practice. The aim of this paper is to investigate corporate communication within the scope of local community relations. This objective is disclosed using a theoretical analysis in the first two parts, and a qualitative study in the third. In this context, the following conclusions stand out. Local community relations are one of the key corporate communication activities. It is therefore communication with organization‘s target audience should be based on a permanent two-way communication, dialogue, cooperation and the mutual benefits. Furthermore, communication with the community is the best when it is responsible and proactive. Organization also should maintain the initiatives arising from the community... [to full text]
83

Multi-Skyrmion solutions of a sixth order Skyrme model

Floratos, Ioannis January 2001 (has links)
In this Thesis, we study some of the classical properties of an extension of the Skyrme model defined by adding a sixth order derivative term to the Lagrangian. In chapter 1, we review the physical as well as the mathematical motivation behind the study of the Skyrme model and in chapter 2, we give a brief summary of various extended Skyrme models that have been proposed over the last few years. We then define a new sixth order Skyrme model by introducing a dimensionless parameter λ that denotes the mixing between the two higher order terms, the Skyrme term and the sixth order term. In chapter 3 we compute numerically the multi-skyrmion solutions of this extended model and show that they have the same symmetries with the usual skyrmion solutions. In addition, we analyse the dependence of the energy and radius of these classical solutions with respect to the coupling constant λ. We compare our results with experimental data and determine whether this modified model can provide us with better theoretical predictions than the original one. In chapter 4, we use the rational map ansatz, introduced by Houghton, Manton and Sutcliffe, to approximate minimum energy multi-skyrmion solutions with B ≤ 9 of the SU(2) model and with B ≤ 6 of the SU(3) model. We compare our results with the ones obtained numerically and show that the rational map ansatz works just as well for the generalised model as for the pure Skyrme model, at least for B ≤ 5. In chapter 5, we use a generalisation of the rational map ansatz, introduced by loannidou, Piette and Zakrzewski, to construct analytically some topologically non-trivial solutions of the extended model in SU(3). These solutions are spherically symmetric and some of them can be interpreted as bound states of skyrmions. Finally, we use the same ansatz to construct low energy configurations of the SU(N) sixth order Skyrme model.
84

Modificação de superfícies para o uso em cultura de células / Surface modification for use in cell culture

Wagner Wlysses Rodrigues de Araujo 16 December 2014 (has links)
O projeto de novos materiais para aplicações tecnológicas em biomateriais e bioengenharia é altamente dependente de como as células aderem à superfície de um material. A adesão e crescimento em biomateriais depende de propriedades do substrato, tais como molhabilidade da superfície, a topografia e a composição química de superfície. O objetivo deste estudo foi investigar as interações de diversos materiais com culturas celulares de células epitelial CHO (Ovário de Hamster Chinês). Os materiais utilizados foram SU-8 2005 (elétron-resiste, Microchem), PDMS (Poli (dimetil siloxano), Down Corning), DLC (Diamond-like Carbon) e vidro foi utilizado como referência. Superfícies de vidro, SU-8, PDMS e DLC lisas (planas) e isentas de modificação ou tratamento específico foram avaliadas quanto ao cultivo de células CHO. Valores médios dos fatores de forma (Ff) de 450 células foram calculados para cada uma das culturas realizadas sobre os 4 substratos. Foram obtidos Ff próximos a 0,52 para o vidro, o SU-8 liso e o DLC, demonstrando um bom espraiamento das células nessas superfícies. A superfície de PDMS apresentou valor unitário para o fator de forma (Ff), que está relacionado a um baixo espraiamento das células. A energia de superfície (ES) obtida para o PDMS é compatível com o resultado de fator de forma (Ff), uma vez que o menor valor para ES é coerente com a baixa adesão celular, o que gerou células com elevado fator de forma (Ff). O SU-8 foi modificado por implantação iônica com uma dose de 1,2x1016 átomos/cm2 e a energia de implantação foi de 8 keV, como referência foi utilizada uma superfície lisa de SU-8 sem implantação. Os resultados mostraram que o número de células vivas por unidade de área foi superior na superfície de SU-8 com prata implantada, mostrando o bom desempenho da cultura nesse substrato. As superfícies de DLC modificadas por tratamento com plasma de oxigênio (DLC-O) e com plasma de hexafluoreto de enxofre (DLC-F) foram utilizadas para cultura celular, os resultados de três experimentos independentes de contagem de número de núcleos (marcados com DAPI) por unidade de área confirmaram os resultados obtidos através do teste de viabilidade (marcados com trypan blue). A superfície de DLC-O, apresentou um maior número de núcleos por unidade de área, quando comparado à superfície DLC-F, da mesma forma que nos resultados obtidos pelo teste de viabilidade. As energias de superfície para as amostras de DLC-F e DLC-O indicaram que a superfície DLC-O é mais hidrofílica do que a superfície DLC-F, que está coerente com o que é conhecido da literatura e com os resultados obtidos em nosso trabalho. Cultura de células CHO foram realizadas em superfícies litografadas com estruturas hexagonais periódicas com o parâmetro 2R (diâmetro do círculo inscrito) sendo 12 µm, 30 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. Estas superfícies foram caracterizadas por microscopia óptica de fluorescência com relação ao número de núcleos (marcados com o fluoróforo DAPI) por unidade de área, isto é, núcleos/mm2. Obteve-se histogramas com o número médio de núcleos por mm2 em três experimentos independentes, onde o número núcleos/mm2 foi consideravelmente maior para 80 µm. As superfícies contendo cavidades periódicas de 12 µm e 30 µm apresentaram dificuldade para as células CHO aderirem à superfície. Em uma outra etapa realizou-se culturas celulares em triplicata dos substratos com as superfícies 12 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. As células em cada uma das superfícies foram analisadas por microscopia óptica (MO) para avaliação da viabilidade celular, utilizando marcador trypan blue. Obteve-se histogramas com os valores médios para o número de células vivas/mm2 para as culturas celulares que corrobora os resultados obtidos no histograma da cultura celular que tiveram os núcleos marcados pelo fluoróforo DAPI. Assim, fica confirmado o melhor desempenho da cultura celular no substrato 80 µm que apresentou o maior número de células vivas/mm2 As micrografias obtidas através de marcação por DAPI foram analisadas através da função de correlação com intuito de se entender como as células estavam organizadas. Isso foi feito para cada uma das superfícies litografadas, 12 µm, 30 µm, 80 µm, 280 µm, 560 µm e também em SU-8 liso. As superfícies dos substratos 80 µm apresentaram os menores valores de distâncias para primeiros e segundos vizinhos, ou seja, as células estão mais próximas umas das outras. As demais superfícies tendem a separar mais as células. Obteve-se também os valores de raio de aglomerado (rc), distância entre os aglomerados (dc) e o número de primeiros vizinhos (Np) através do ajuste da função de correlação. A análise de correlação mostrou com clareza o que não era evidenciado apenas visualizando-se as imagens. Ela mostra que as células, mesmo em SU-8 liso tem a forte tendência de formar aglomerados de células com raio de aproximadamente 45 µm. No caso de substratos lisos, células CHO apresentaram a melhor adesão na superfície do SU-8, seguido do DLC, enquanto que o PDMS foi a pior situação, devido à baixa molhabilidade do material. No caso de superfícies com microestrutura, SU-8 contendo microcavidades hexagonais de 12 e 30 µm mostraram ser as situações mais adversas para o crescimento de células CHO, provavelmente por causa da topografia das cavidades serem de menor tamanho quando comparadas ao tamanho das células CHO. Em vez disso, SU-8, contendo microcavidades hexagonais de 80 µm foi a superfície mais favorável para o crescimento de células CHO. / The design of new materials for technological applications in biomaterials and bioengineering is highly dependent on how the cells adhere to the material surface. The cells adhesion and growth on biomaterials depends on substrate properties such as surface wettability, topography and the chemical composition. The aim of this study was to investigate the interactions of various materials with cell cultures of epithelial cells CHO (Chinese Hamster Ovary). The materials used were SU-8 2005 (electron resists, Microchem), PDMS (poly (dimethyl siloxane), Dow Corning), DLC (Diamond-like Carbon) and glass was used as reference. Unmodified and flat surfaces of glass, SU-8, PDMS and DLC were evaluated for the culture of CHO cells. Form factor (Ff) values were calculated as average of 450 cells for each of the cultures performed on the four substrates. Ff close to 0.52 was obtained for flat surfaces of glass, SU-8 and DLC, showing a good cell spreading on these surfaces. The surface of PDMS presented a form factor (Ff) near unity, which is related to low spreading cell. The surface energy (ES) obtained for the PDMS is coherent with the Ff result, since the smallest value of ES is consistent with the low cell adhesion, which resulted in cells with a high Ff. The SU-8 was modified by ion implantation using a dose of 1.2x1016 atoms/cm2 and an implantation energy of 8 keV, unmodified flat SU-8 was used as a reference. The cell culture results showed that the number of live cells per unit area was greater in the SU-8 surface implanted with silver, showing a good performance in the culture substrate. The DLC surfaces modified by plasma treatment with oxygen (DLC-O) and sulfur hexafluoride (DLC-F) were used for cell culture. The results of three independent experiments, counting the number of nuclei (marked with DAPI) per unit area, confirmed the results obtained by the viability test (marked with trypan-blue). The surface of the DLC-O had higher number of nuclei per unit area when compared to the surface of the DLC-F, similarly to the results obtained for the viability test. The surface energies of the DLC-F and DLC-O samples indicated that the DLC-O surface is more hydrophilic than the DLC-F surface, which is consistent with results obtained with our work and with the literature. CHO cell culture were performed on surfaces with periodic hexagonal structures with the diameter of inscribed circle (2R) given by 12 µm, 30 µm, 80 µm, 280 µm, 560 µm and also on flat SU-8. These surfaces were characterized by fluorescence optical microscopy with respect to the number of nuclei (marked with fluorophore DAPI) per unit area, i.e. nuclei/mm2. Histograms were obtained for the average number of nuclei per mm2 in three independent experiments, where the substrate with periodic hexagonal structures with 2R = 80 µm presented considerably higher nuclei/mm2. Surfaces containing periodic cavities of 2R =12 µm and 30 µm were adverse for CHO cells adhesion. In another approach, cell culture were analyzed by light microscopy (LM) for evaluation of cell viability using trypan-blue marker. This was carried out in triplicate cell culture on substrates with surfaces 12 µm, 80 µm, 280 µm, 560 µm and also on flat SU-8. Histograms were generated for average number of living cells/mm2 for each substrate, which corroborates with the results obtained for the cell culture marked with fluorophore DAPI. Thus, it is confirmed the better performance of the cell culture on substrates with 2R = 80 µm, presenting the highest number of living cells/mm2. The micrographs obtained with cells marked with DAPI were analyzed through the correlation function with the aim of understanding how the cells were organized. This was performed for each of the lithographed surfaces 12 µm, 30 µm, 80 µm, 280 µm, 560 µm and also flat SU-8. The surfaces of the substrates with 2R = 80 µm had the lowest values for length between its neighbors, that is, the cells are closer to each other. The remaining surfaces tend to separate the cells. Also were obtained the cluster radius values (rc), the distance between the clusters (dc) and the number of nearest neighbors (Np) through the correlation function fitting. The correlation analysis clearly showed what was not possible to observe by viewing the images. It shows that the cells, even in flat SU-8, have a strong tendency to form clusters of cells within about 45 micrometers. In the case of flat substrates, CHO cells exhibited better adhesion to the surface of SU-8, followed by the DLC, while the PDMS was worse due to low wettability of the material. In the case of surfaces with microstructures, SU-8 containing hexagonal microstructures of 12 and 30 µm showed to be the most adverse conditions for the CHO cell growth, probably because of the topography of the cavities being smaller in size compared to the size of CHO cells. SU-8 with 80 µm hexagonal microstructures was more favorable surface for the growth of CHO cells.
85

On flux vacua, SU(n)-structures and generalised complex geometry / Sur des vides à flux, des SU(n)-structures et de la géométrie complexe généralisée

Prins, Daniël 25 September 2015 (has links)
Pour connecter la théorie des cordes à la physique observable, il est essentiel de comprendre des vides supersymmétriques à flux non triviaux. Dans cette thèse, ils sont étudiés en deux cadres mathématiques : les SU(n)-structures et la géométrie complexe généralisée. Les variétés équipées de SU(n)-structures sont des généralisations de variétés de Calabi-Yau. La géométrie complexe généralisée est un cadre géométrique qui regroupe les géométries complexe et symplectique. On donne des classes de vide à flux de supergravité de type II et de théorie-M sur des variétés équipées de SU(4)-structures. Des vides explicites sont donnés sur l'espace de Stenzel, un Calabi-Yau non-compact. Ensuite, sur cette variété, des familles de SU(4)-structures sont construites. À l'aide de celles-ci, on trouve des vides à flux sur des variétés non-symplectiques. Il est démontré que les conditions permettant une supersymétrie à d = 2, N = (2,0) de type IIB peut être reformulées dans le langage de la géométrie complexe généralisée, partiellement interprétables en termes de conditions d'intégrabilité de structures presque complexes généralisées. Enfin, la théorie de type II euclidienne est examinée sur des variétés équipées de SU(5)-structures, donnant des équations généralisées qui sont nécessaires mais pas suffisantes pour satisfaire les équations de supersymétrie. Des classes de solutions explicites sont également donnés / Understanding supersymmetric flux vacua is essential in order to connect string theory to observable physics. In this thesis, flux vacua are studied by making use of two mathematical frameworks: SU(n)-structures and generalised complex geometry. Manifolds with $SU(n)$ structure are generalisations of Calabi-Yau manifolds. Generalised complex geometry is a geometrical framework that simultaneously generalises complex and symplectic geometry. Classes of flux vacua of type II supergravity and M-theory are given on manifolds with SU(4) structure. The N = (1,1) type IIA vacua uplift to N=1 M-theory vacua, with four-flux that need not be (2,2) and primitive. Explicit vacua are given on Stenzel space, a non-compact Calabi Yau. These are then generalised by constructing families of non-CY SU(4)-structures to find vacua on non-symplectic SU(4)-deformed Stenzel spaces. It is shown that the supersymmetry conditions for N = (2,0) type IIB can be rephrased in the language of generalised complex geometry, partially in terms of integrability conditions of generalised almost complex structures. This rephrasing for d=2 goes beyond the calibration equations, in contrast to d=4,6 where the calibration equations are equivalent to supersymmetry. Finally, Euclidean type II theory is examined on SU(5)-structure manifolds, where generalised equations are found which are necessary but not sufficient to satisfy the supersymmetry equations. Explicit classes of solutions are provided here as well. Contact with Lorentzian physics can be made by uplifting such solutions to d=1, N = 1 M-theory
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Value at Risk portfolia českých akcií při použití alternativních rozdělení / Value at Risk Calculation of the Czech Stock Portfolio Using Alternative Distributions

Hédl, Tomáš January 2011 (has links)
The aim of this diploma thesis is to analyze ways of Value at Risk calculation. Its core is to get a suitable model that could most appropriately reflect the probability distribution of returns of the Czech stock portfolio that we have generated. In this thesis we find out that the returns follow unbounded distribution which was first described by Johnson (1949). Since we detect that returns are correlated we have to apply appropriate autoregressive process that removes this dependency. In the empirical part we discover an inability of models based on assumptions of normality, to correctly predict the Value at Risk. Historical simulation methods, which have promising backtesting results, are rejected because of the slow adaptation to the recent changes in the market. However, we find a way how to implement Johnson SU distribution into the GARCH model. This model, which passes all the tests, is thus able to predict Value at Risks of the portfolio most accurately. JEL Classification: C16, C22, G11 Keywords: Market risk, Value at Risk, Risk management, Johnson SU distribution
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Nevyriausybinių organizacijų ryšių su visuomene organizavimo principai ir priemonės / The principles and tools for public relations organization in non-governmental organizations

Misiukonytė, Lina 15 June 2011 (has links)
Magistrantūros studijų baigiamasis darbas, 48 puslapių, 11 paveikslai, 12 lentelės, 38 literatūros šaltiniai, 4 priedai, lietuvių kalba. Tyrimo objektas – NVO ryšiai su visuomene. Tyrimo tikslas – pagrįsti nevyriausybinių organizacijų ryšių su visuomene organizavimo modelį. Tyrimo uždaviniai: 1) Išnagrinėti ryšių su visuomene teorinius dėsningumus. 2) Ištirti ir įvertinti ryšių su visuomene organizavimo būklę vietos veiklos grupėje „Lamatos žemė“ ir Lietuvos kaimo turizmo asociacijoje. 3) Identifikuoti NVO ryšių su visuomene organizavimo principus ir priemones bei aprašyti jų ypatumus. Tyrimo metodai: mokslinės literatūros analizės, anketinės apklausos, dokumentų analizės ir sintezės, loginės analizės, indukcijos ir dedukcijos, palyginimo ir grafinio modeliavimo metodai. Tyrimo rezultatai: • pirmojoje darbo dalyje, nagrinėjama užsienio bei Lietuvos autorių mokslinė literatūra, padedanti atskleisti ryšių su visuomene sampratą, prasmę bei funkcijas nevyriausybinėse organizacijose; • antrojoje darbo dalyje atliktas vietos veiklos grupės „Lamatos žemė“ ir Lietuvos kaimo turizmo asociacijos ryšių su visuomene veiklos organizavimo empirinis tyrimas išanalizuotos taikomos priemonės; • trečiojoje darbo dalyje pateiktas nevyriausybinių organizacijų ryšių su visuomene organizavimo modelis, apibrėžti pagrindiniai principai; Darbe daromos išvados, kad nevyriausybinėse organizacijose ryšių su visuomene funkcija yra tik viena iš įvaizdžio formavimo funkcijų, ne dažnai yra horizontali... [toliau žr. visą tekstą] / Final work of University Postgraduate Studies, 48 pages, 11 figures, 12 tables, 38 references, 4 appendixes, in the Lithuanian language. Research object – public relations in non-govermental organizations. Research aim – to provide the model for organization of public relations in non-govermental organization. Objectives of the research: • to analyze consistent pattern of public relations; • to analyze and evaluate the state of public relations organization in Local action group „Lamatos žemė“ and association of rural turism in Lithuania; • to identify the principles and tools of public relations in the non-govermental organization and to discribe their characteristics. Methods of research – analysis and synthesis of scientific literature and documents, induction and deduction, questionnaire, logical analysis, comparative and graphical representation methods. Research results: • The first part analyzes scientific literature by foreign and Lithuanian authors, that helps to disclose conception, meaning and functions of public relations in non-govermental organizations. • The second part conducts an empirical investigation of public relations practice in Local action group „Lamatos žemė“ and association of rural turism in Lithuania, analyses the applied measures. • The third part presents the model of public relations organization in non-govermental organizations and defines the basic principles. In conclusion, the function of public relations is one of image formation... [to full text]
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歐陽修、蘇軾辭賦之比較研究

陳韻竹, CHEN, YUN-ZHOU Unknown Date (has links)
本論文旨在比較歐陽修、蘇軾二家辭賦之風格,考其藝術成就,形式特色,並觀照宋 代古文運動,與其古文理論相互印證。分為七章,約十二萬言。 第一章:緒論。乃概述辭賦的流變,並釐定研究範圍,說明研究動機與目的,以及研 究重點與方法。 第二章:歐陽修辭賦之評介。先研析歐陽修生平,再對歐陽修辭賦逐篇評介,考其著 作年代,稽鉤其事實,探究其動機,並略述其大意。 第三章:歐陽修辭賦之分析。將歐陽修辭賦略分為古賦、駢賦、律賦、文賦四類,逐 項分析之,而由當時之文學背景、文學風尚,以見其形式特色和時代意義。 第四章:蘇軾辭賦之評介。循第二章之規模,研討蘇軾生平,再就諸篇辭賦之著作年 代、背景、動機、內容大要,加以分析。 第五章:蘇軾辭賦之分析。乃將蘇軾辭賦略分為辭、古賦、駢賦、律賦、文賦五類, 由歐、蘇承傳之脈絡,以見二者之異同,探討蘇軾卓然不群之風格。 第六章:歐、蘇辭賦之綜合比較。本章由組織結構、修辭技巧、情志內涵三端,探討 歐、蘇辭賦之內質與外象,全面的觀照並比較之。 第七章:結論:乃將歐、蘇之古文理論,與其辭賦表現相互印證,並述其文學成就與 影響。
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Lee-Yang zeros analysis of finite density lattice QCD

Crompton, P. R. January 2001 (has links)
No description available.
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Web 2.0 interneto svetainės sėkmę sąlygojantys veiksniai: Web 2.0 interneto projekto „In Belly“ paleidimas Anglijoje / Identifying success factors of web 2.0 sites:"the launch of web2.0 project "in belly" in united kingdom

Zakarevičiūtė, Agnė 25 June 2014 (has links)
Magistro darbo objektas - web 2.0. interneto svetainės sėkmę lemiantys veiksniai. Darbo tikslas - išsiaiškinti, kaip sukurti sėkmingą web 2.0 interneto svetainę. Darbo uždaviniai - atskleisti, kokie veiksniai sąlygoja web 2.0 interneto svetainių sėkmę; išsiaiškinti, kokia yra interneto svetainių kokybės vertinimo metodologija; atskleisti, kokios ryšių su visuomene priemonės galėtų būti naudojamos viešinant web 2.0 interneto svetainę; išanalizuoti, kokie yra web 2.0 interneto svetainei www.inbelly.co.uk lankytojų keliami kokybės reikalavimai; išsiaiškinti, kokie ryšių su visuomene veiksmai būtų efektyviausi viešinat web 2.0 interneto svetainę „www.inbelly.co.uk; Išanalizavus mokslinę literatūrą, taikant analogijos metodus interneto svetainės sėkmę nutarta matuoti unikalių lankytojų skaičiumi, lankytojų dalyvavimo aktyvumu ir lojalių lankytojų skaičiumi. Prieita prie išvados, kad pagrindiniai interneto svetainės sėkmę lemiantys veiksniai yra lankytojų keliamų kokybės kriterijų nustatymas, interneto svetainės kokybės įvertinimas ir svetainės viešinimas, naudojant ryšių su visuomene priemones. Analizuojant interneto svetainių kokybės vertinimo metodologijas, nutarta, kad interneto svetainės kokybė turi būti vertinama pagal tai, kaip ją suvokia lankytojas. Lankytojų kokybės reikalavimai priklausomai nuo svetainės tipo skiriasi, siekiant išsiaiškinti, kurie kokybės elementai yra svarbiausi, svarbu atlikti konkrečios interneto svetainės kokybės vertinimą. Išanalizavus mokslinę... [toliau žr. visą tekstą] / Internet has become a very important communication platform, public relation specialist must learn, how to use its tools effectively. The subject of this Master's research – success factors of web2.0 internet sites. The aim is to find out, how to create successful websites. Job tasks: to reveal the factors, that determine success of websites; to detect the methodology of website quality evaluation; to reveal what public relations tools might be used in promoting web2.0. internet site; to analyze, what quality demands are required for the website www.inbelly.co.uk; to find out, what public relation tools would be most effective in promoting www.inbelly.co.uk website. After analyzing the literature, we can notify that the object has been goaled. After analysing scientific literature, using the analogy approaches, it was decided to measure website success by the number of unique visitors, visitors participation in the activity and the number of loyal users. It was concluded that the key to web site success is measuring the quality demands from a user‘s perspective, the website quality assessment, and publicity for the site, using public relations tools. After analyzing web site quality assessment methodologies it was agreed that the web site quality should be judged by its visitor‘s assessments. Visitors' quality requirements differences depending on the website type, that‘s why it is important to perform a specific website quality assessment. The analysis of scientific... [to full text]

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