Thesis (M.A.)--University of Virginia, 1998. / Description based on content as of June 1999; title from title screen.

In this thesis, we design and develop new approximation algorithms and complexity results for three guarding and partitioning problems on orthogonal polygons; namely, guarding orthogonal polygons using sliding cameras, partitioning orthogonal polygons so as to minimize the stabbing number and guarding orthogonal terrains using vertex guards. We first study a variant of the well-known art gallery problem in which sliding cameras are used to guard the polygon. We consider two versions of this problem: the Minimum- Cardinality Sliding Cameras (MCSC) problem in which we want to guard P with the minimum number of sliding cameras, and the Minimum-Length Sliding Cameras (MLSC) problem in which the goal is to compute a set S of sliding cameras for guarding P so as to minimize the total length of trajectories along which the cameras in S travel. We answer questions posed by Katz and Morgenstern (2011) by presenting the following results: (i) the MLSC problem is polynomially tractable even for orthogonal polygons with holes, (ii) the MCSC problem is NP-complete when P is allowed to have holes, and (iii) an O(n)-time exact algorithm for the MCSC problem on monotone polygons. We then study a conforming variant of the problem of computing a partition of an orthogonal polygon P into rectangles whose stabbing number is minimum over all such partitions of P. The stabbing number of such a partition is the maximum number of rectangles intersected by any orthogonal line segment inside the polygon. In this thesis, we first give an O(n log n)-time algorithm that solves this problem exactly on histograms. We then show that the problem is NP-hard for orthogonal polygons with holes, providing the first hardness result for this problem. To complement the NP-hardness result, we give a 2-approximation algorithm for the problem on both polygons with and without holes. Finally, we study a variant of the terrain guarding problem on orthogonal terrains in which the objective is to guard the vertices of an orthogonal terrain with the minimum number of vertex guards. We give a linear-time algorithm for this problem under a directed visibility constraint. / February 2016

The thesis focuses on extending collecting activities across the Czech lands and the associated founding of the first institutions of museum and gallery character. The first part deals with Společnost vlasteneckých přátel umění (The Society of Patriotic Friends of Art) and its founders and supporters, which is followed by a chapter concerning collectors and patrons in Bohemia and Moravia in the 19th and early 20th centuries. The second part of the thesis deals with the area of South Bohemia, České Budějovice in particular, with one chapter devoted to the South Bohemian Museum. The author mainly focuses on the origins, history and significant personalities associated with its operation. The subsequent sections deal with two major natives of Ceske Budejovice and its surroundings, an industrialist Vojtech Lanna, later acting in Prague, and a businessman and a politician August Zátka, who, thanks to his social activities played an important role in the early days of collecting and patronal activities of the Zátka family.

xi, 125 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / This dissertation presents experimental and theoretical studies of radiation pressure cooling in silica optomechanical microresonators where whispering gallery modes (WGMs) are coupled to thermal mechanical vibrations. In an optomechanical system, circulating optical fields couple to mechanical vibrations via radiation pressure, inducing Stokes and anti-Stokes scattering of photons. In analogy to laser cooling of trapped ions, the mechanical motion can in principle be cooled to its ground state via the anti-Stokes process in the resolved-sideband limit, in which the cavity photon lifetime far exceeds the mechanical oscillation period. Our optomechanical system is a slightly deformed silica microsphere (with a diameter 25-30 μm ), featuring extremely high Q -factors for both optical ( Q o ∼ 10 8 ) and mechanical ( Q m ∼ 10 4 ) systems. Exploiting the unique property of directional evanescent escape in the deformed resonator, we have developed a free-space configuration for the excitation of WGMs and for the interferometric detection of mechanical displacement, for which the part of input laser that is not coupled into the microsphere serves as a local oscillator. Measurement sensitivity better than 5 × 10 -18 m /[Special characters omitted.] has been achieved. The three optically active mechanical modes observed in the displacement power spectrum are well described by finite element analysis. Both radiation pressure cooling and parametric instabilities have been observed in our experiments. The dependence of the mechanical resonator frequency and linewidth on the detuning as well as the intensity of the input laser show excellent agreement with theoretical calculations with no adjustable parameters. The free-space excitation technique has enabled us to combine resolved sideband cooling with cryogenic cooling. At a cryogenic temperature of 1.4 K, the sideband cooling leads to an effective temperature as low as 210 m K for a 110 MHz mechanical oscillator, corresponding to an average phonon occupation of 37, which is one of the three lowest phonon occupations achieved thus far for optomechanical systems. The cooling process is limited by ultrasonic attenuation in fused silica, which should diminish when bath temperature is further lowered, with a 3 He cryostat, to a few hundred millikelvin. Our experimental studies thus indicate that we are tantalizingly close to realizing the ground-state cooling for the exploration of quantum effects in an otherwise macroscopic mechanical system. / Committee in charge: Michael Raymer, Chairperson, Physics; Jens Noeckel, Member, Physics; Hailin Wang, Member, Physics; Paul Csonka, Member, Physics; Jeffrey Cina, Outside Member, Chemistry

This thesis deals with the problems of reception of art works. The theoretical part induces this theme. It lists the most common factors which influencing our perception and assessment of art works and watching them from the position of art teacher. The practical part is trying to work with these findings in the glass objects and is also verified in the pedagogical work with children in the gallery.

Ce travail de thèse a consisté à mettre en place toute une filière de fabrication de microtores en silice sur silicium (étapes de lithographie et de gravure en salle blanche pour la réalisation de microdisques, installation d'un banc optique permettant la transformation du résonateur en microtore par un procédé de recuit laser CO2), à installer un banc optique permettant de mesurer la largeur spectrale de leurs résonances optiques à 1.55 µm et enfin, à explorer l'intégration d'émetteurs de lumière composés d'éléments de la colonne IV comme du silicium et du germanium, dans ces cavités. Des microtores supportant des résonances de facteur de qualité Q proche de 10^8 à 1.55 µm ont été fabriqués. Ces réalisations sont très proches de l'état de l'art et valident à la fois la fabrication des cavités et le banc optique permettant les mesures spectrales des modes de galerie (WGM). Grâce à un contrôle fin des différentes étapes de fabrication, de nouveaux résonateurs ont également été réalisés, des microsphères de silice sur puce de petits rayons (entre 5 et 14 µm). Une étude détaillée de ces résonateurs est présentée. Des Q proches de 10^8 ont également été mesurés. Des cavités WGM comportant une couche de nanoclusters de silicium dans une matrice de silice avec des ions erbium (SiOx : Er) sont étudiées en photoluminescence. Un couplage des ces émetteurs à des WGM est observé à température ambiante dans le visible et dans l'infrarouge. Un travail de couplage du germanium aux WGM a commencé et semble prometteur. / This work consisted in developing a fabrication process of silica microtoroids on a silicon chip (steps of lithography and etching in clean room for the realization of microdisks, set up of an optical bench to form a microtoroid with a reflow treatment of a silica microdisk by a CO2-laser), setting up an optical bench to measure the linewidth of their optical resonances at 1.55 µm and finally, exploring light emitters integration in these cavities such as silicon and germanium. Very high quality-factors (Q) close to 10^8 at 1.55µm have been measured on microtoroids. These realizations are very close to the State of the art and validate both the fabrication of these cavities and the optical bench to measure the linewidth of their Whispering Gallery Modes (WGM). With a precise control of the fabrication steps, new resonators have also been fabricated, silica microspheres on a chip with small radii (5 < r < 14µm). An in-depth study of these last ones is presented. Q-factors close to 10^8 have also been measured on microspheres. WGM cavities with a SiOx: Er layer (silicon nanoclusters in silica with erbium ions) are studied by photoluminescence. Coupling of these light emitters to WGM is observed in visible and near infrared at room temperature. A work of coupling of germanium to WGM began and seems promising.

The study investigates how museum and gallery buildings can be designed to give functional longevity and appeal. It considers this in terms of their design and relation to their surroundings and use in the context of changing social, cultural, political and economic factors. Post World War II the typological design and layout of these buildings was challenged; partly as a result of the influence of modernism and also as new modes of art production challenged the spaces and display modes. Financial instability and class perception have always been problematic and increased public expectations add to issues that need addressing. The study investigates how these factors have impacted on these buildings and if this has influenced their design and use. It considers the regional context of the West Midlands and also draws comparisons to other areas in England to investigate ways of addressing contemporary issues to achieve longevity of use. The study considers the historical influence of the typological developments. Examples from the West Midlands and investigation of the area’s historical background are used to identify if regional idiosyncrasies exist and if these influence a building’s longevity. This establishes their contemporary context and objectively reviews the resulting implications of appearance and function in relation to the social, cultural and economic issues that may be dominant within this region. A qualitative interview methodology and analysis is used to examine the views of a multidisciplinary group of museum and gallery users, capturing a snapshot in time of their views on the appearance, understanding and use of these buildings. This information is analysed and discussed in conjunction with the findings of the relevant literature. The comparison of the information researched raises regional and national issues associated to design and use of these buildings. Four key themes related to the longevity of use emerged; architectural design, location, economic viability and inclusivity.

Esta dissertação visa entender as implicações do projeto arquitetônico no momento da execução de obras efêmeras, bem como busca elucidar os paradigmas essenciais a este projeto frente ao estágio avançado de depredação dos meios naturais em que o planeta se encontra. Entretanto, ainda que com a escassez de referências bibliográficas sobre o tema, na busca por esse pensamento analisaremos três pavilhões de verão da Galeria Serpentine executados por arquitetos de grande importância no cenário atual acreditamos que o conceito em arquitetura fica plasmado na obra. A leitura desses objetos, organizados não verbalmente, necessita de um referencial capaz de elucidar a sintaxe do pensamento que o orienta, revelando através de dados icônicos e indiciais o repertório de seu projetista. Neste momento mostra-se fecunda a teoria da semiótica de Charles Sanders Peirce, não apenas para revelar o repertório do arquiteto e os paradigmas de projeto que o orientam, mas também para pesquisar de que maneira estes profissionais materializam seus pensamentos através da linguagem não-verbal da arquitetura. Por outro lado, o que se vê à exaustão em eventos comerciais é a utilização de semelhantes sistemas construtivos industrializados, dos quais o OCTANORM é o mais conhecido, o que garante a continuidade do processo moderno e a elevação da capacidade de montagem e desmontagem como valor principal da obra. As hipóteses aqui levantadas tomam estes sistemas como uma manifestação da continuidade e apontam para outras arquiteturas, ainda efêmeras, mas alheias a essa dinâmica e com especificidades que caracterizam um campo particular de estudo. A base epistemológica deste trabalho veicula muito a semiótica peirciana e a bibliografia fundamental que dá orientação à pesquisa tem origem na filosofia da arquitetura e na psicologia da percepção com diversos teóricos. / This dissertation intends to understand the architectural project implications in the moment of the execution of ephemeral works, and tries to elucidate the essential paradigms to this project due to the advanced stage of depredation found within the planets natural resources. However, even facing a bibliographic shortage on the theme, searching this thought, we will analyze three summer pavilions inside Serpentine Gallery, executed by well-known architects we believe that the concept in architecture remains in this work. The reading of these objects, non-verbally organized, needs a reference capable of elucidating the thought syntax that guides it, revealing the designer repertory through iconic and inkling data. In this moment, Charles Sanders Peirces theory is shown to be abundant, not only to reveal the architectural repertory and the projects paradigms that guide it, but also to find the way that these professionals turn their thoughts into matter through non-verbal architectural language. On the other hand, what is exhaustively seen throughout commercial events is the use of similar industrialized constructive systems, from which OCTANORM is the most known, what guarantees the continuity of the modern process and the elevation of the mounting an dismounting capability as the main value of the work. The hypotheses raised in here consider these systems as a manifestation of continuity and point to other architectures, still ephemeral, but disconnected to this dynamic and owners of specificities that characterize a particular field of study. The basis of this work, regarding the use of epistemology, features peircians semiotics a lot and, the fundamental bibliography, that gives the research an orientation, has its origin in the architecture philosophy and in the psychology of perception defended by many theorists.

Submitted by (edna.saturno@ufrpe.br) on 2016-06-15T14:06:34Z No. of bitstreams: 1 Clovis Eduardo de Souza.pdf: 1430086 bytes, checksum: 65f73e32bdcc02f7ed8c352d28a39d12 (MD5) / Made available in DSpace on 2016-06-15T14:06:34Z (GMT). No. of bitstreams: 1 Clovis Eduardo de Souza.pdf: 1430086 bytes, checksum: 65f73e32bdcc02f7ed8c352d28a39d12 (MD5) Previous issue date: 1998-11-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The riparian vegetation along the São Francisco river has been suffering a strong degradation by the human action. As consequence exist a drastic reduction in the covering degree of the native vegetation and sediment deposition that has causing threatens own existence of the river. Thisstudy intends to contribute for the comprehension of the caatinga vegetation that happens in the margins of the São Francisco river, by the establishment of the relationships between topographical and pedological factors and distribution of woody plants. The floristic and phytosociological survey was carried out, during twelve months, in area of EMBRAPA-SPSB, in Petrolina-Pernambuco. Was open a transect starting from the margin of the river, with the length of 800 m, where 138 contiguous plots of 10 X 10 m were installed. In each plot was measured the stem at soil level (DNS) for all individuals, alive or dead, with diameter > 3 cm and total height > 1m. Along this transect a difference of 9,40m was registered and five topographic environments were identified: river side (MR), dike (D), floodable depression (DI), boundary terrace (TL), all of them belonging to the fluvial terrace, with Alluvial and Cambisol eutrophic silty soils and the inlander tableland (TS) with red-yellow silty texture Podzolic soil. Forty-eight species/morphospecies distributed in 39 genera and 21 families were identified. Four phytogeoenvironments, MR, D+TL, DI+TL and TS, were defined by environmental variations and the floristic similarity among the parcels, calculate using cluster analysis. The MRenvironment showed the largest total density, total basal area, maximum and medium height and maximum diameter, and besides also, presented 8,1% of the plants with superior height to 8m, against 0,6% of D+TL, 0,2% of DI+TL and 0% of TS. The species with the largest importance value index were Inga vera subsp. affinis in MR, Mimosa bimucronata in D+TL and DI+TL and M. tenuiflora in TS. / A vegetação ciliar ao longo do rio São Francisco tem sofrido uma forte degradação pela ação antrópica, causando uma drástica redução da cobertura vegetal nativa, que tem provocado um contínuo processo de assoreamento o que tem colocado em perigo a própria existência do rio. Com o propósito de contribuir para o conhecimento da vegetação de caatinga ocorrente nas margens do rio São Francisco e estabelecer suas relações com os fatores topográficos e pedológicos, foi realizado, durante o período de doze meses, o levantamento florístico e fitossociológico do componente arbustivo-arbóreo da vegetação, em área da EMBRAPA-SPSB, em Petrolina-PE. Foi aberto um transecto a partir da margem do rio, com o comprimento de 800 m, onde foram instaladas 138 parcelas contíguas de 10 x 10 m, para amostragem de todos os indivíduos vivos ou mortos ainda em pé, que tivessem o diâmetro do caule ao nível do solo ³ 3 cm e altura total ³ 1 m. Ao longo do transecto foi registrado um desnível de 9,4 m e identificados cinco ambientes topográficos: margem do rio (MR), dique (D), depressão inundável (DI), terraço limite (TL), todos pertencentes ao terraço fluvial, com solos Aluvial e Cambissolo eutrófico textura siltosa, e o tabuleiro sertanejo (TS) com solo do tipo Podzólico vermelho-amarelo textura arenosa. Foram encontradas 48 espécies/morfoespécies, distribuídas em 39 gêneros e 21 famílias, registrados quatro fitogeoambientes: MR, D+TL, DI+TL e TS, com base nos aspectos morfopedológicos e na similaridade florística entre as parcelas, calculada através da análise de agrupamento, e identificados os diferentes conjuntos florísticos ligados ao terraço fluvial e ao tabuleiro sertanejo. Do ponto de vista fisionômico, a MR destacou-se dos demais ambientes pela maior densidade total, área basal total, alturas máxima e média e diâmetro máximo, além de apresentar 8,1% dos indivíduos com altura superior a 8 m, contra 0,6% do D+TL, 0,2% do DI+TL e 0% do TS. As espécies com maior índice do valor de importância (IVI) foram: Inga vera subsp. affinis na MR, Mimosa bimucronata no D+TL e DI+TL e M. tenuiflora no TS.

A necessidade de recuperação de áreas ciliares degradadas tem subsídio na legislação, porém, o uso de sistemas agroflorestais para esse fim não é permitido. O objetivo desse trabalho é comparar a capacidade de recuperação de dois sistemas agroflorestais e de um plantio florestal com espécies arbóreas nativas, também avaliando as diferenças de custos de implantação e manejo. A pesquisa foi realizada no Estado de São Paulo, município de Piracicaba, às margens do Rio Corumbataí, na propriedade da Usina Costa Pinto, onde o cultivo de cana-de-açúcar ocupa a maior parte do uso do solo. Os tratamentos foram: (1) testemunha; (2) sistema florestal, com 10 espécies arbóreas nativas; (3) sistema agroflorestal simples, com as mesmas arbóreas nativas, guandu e feijão-de-porco como adubo verde; (4) sistema agroflorestal complexo, com diversas espécies frutíferas, girassol e capim napier, além das mesmas arbóreas nativas e das duas leguminosas. Os fatores mensurados foram: altura e diâmetro à altura do colo das arbóreas nativas, custos, liberação de CO2 do solo, biomassa microbiana e fertilidade do solo. O SAF simples apresentou as maiores alturas médias, com um aumento de 36% em relação ao sistema florestal. O SAF complexo apresentou resultados intermediários, com altura média 10% superior à do sistema florestal. Separando as espécies em pioneiras e não pioneiras, as primeiras não apresentaram diferença entre os tratamentos, tendo as não pioneiras crescido cerca de 35% melhor no SAF simples. Supõe-se que as leguminosas tenham cumprido a função de pioneiras, melhorando o ambiente e propiciando o melhor crescimento das não pioneiras. A média do diâmetro de todas as espécies para cada tratamento apresentou diferença entre o SAF simples (51% maior) e o SAF complexo, sendo ambos semelhantes ao sistema florestal, que foi intermediário. Entre pioneiras e não pioneiras, as diferenças foram semelhantes, sendo o SAF simples 67% superior ao SAF complexo, entre as pioneiras, e 33% superior entre as não pioneiras. As análises de solo, tanto de biomassa microbiana, liberação de CO2 ou de fertilidade, não mostraram diferenças entre os tratamentos. Numa estimativa com base nas modificações sugeridas a partir dos dados do experimento, o SAF simples pode ter um custo 16% inferior ao do sistema florestal, principalmente devido à redução da necessidade de manutenção do sistema. O SAF complexo apresentou o maior custo dos três tratamentos, pois, além da grande demanda de mão-de-obra, o sistema encontra-se fora dos padrões legais para venda de sementes. O estudo da heterogeneidade do ambiente reforça a necessidade do uso de métodos de implantação e de manejos diferentes para cada situação encontrada e permitiu inter-relacionar os blocos quanto à degradação, com base nas médias dos blocos, para todos os parâmetros avaliados. Seguindo critérios semelhantes, as espécies arbóreas nativas também foram ordenadas segundo a sucessão, de acordo com a teoria de Götsch: Sangra d’água, Embaúba, Cordia, Mutambo, Pau Viola, Tamboril, Trema, Canafístula, Aroeira, Canelinha. Em condições de grande fragmentação da matriz florestal e forte domínio de gramíneas, o uso de sistemas agroflorestais na recuperação de matas ciliares pode trazer efeitos positivos ao crescimento das árvores nativas e redução no custo de implantação. / Riparian forest is the vegetation that borders rivers, ponds and lakes, and although it is protected by law, agricultural systems are widely used in these areas. Restoration of deforested riparian zones is requested by law, but agroforestry systems are not accepted for this purpose. The objective of this research was to compare the restoration success and the costs of three kinds of restoration management systems: two agroforestry systems and one forestry system, intending to give basis for changes in public policies. This research was carried out in São Paulo State, Piracicaba County, in the Corumbataí River watershed, in the farm of Usina Costa Pinto, where sugar cane fills most of the lanscape. The treatments were: (1) control; (2) forestry system, with 10 native tree species; (3) agroforestry system 1, where two herbaceous/shrub legume species were included in addition to trees; (4) agroforestry system 2, were 10 edible fruit species, sunflower and napier grass were added. Management was evaluated by measuring height and diameter of the native tree species, soil respiration, microbial biomass and soil fertility. Comparing the mean height of all species, agroforestry system 1 showed the best results, which was 36% better than the forestry system. Agroforestry system 2 showed intermediate results: mean height was 10% higher than the one achieved in forestry system. When the species were grouped according to ecological succession, pioneers didn’t present any difference between treatments, but not-pioneers grew 35% better in agroforestry system 1. Probably, legume plants played the role of pioneers, improving the environment and supporting a better development of the non-pioneers. The mean diameter at ground level of all the species showed differences between agroforestry system 1 (51% better) and agroforestry system 2, but both were not different from the forestry system, which had intermediate results. There were similar differences when the species were grouped in pioneers and non-pioneers. For pioneers, agroforestry system 1 was 67% better than agroforestry system 2 and, for non pioneers, this difference was of 33%. There were no differences among treatments in soil fertility, microbial biomass and soil respiration. Estimating the costs, on the basis of modifications suggested after data analysis, agroforestry systems 1 may cost 16% less than forestry system, due to less necessity of interventions for weeds control. Agroforestry system 2 had the highest cost because it demanded much more work than other treatments and this system, like agroforestry system 1, is out of legal standard for seed production. Studies on the environment heterogeneity allowed to rank blocks, based on the block means of all the measured parameters. Based on the same principles, the native tree species were also ranked according to Götsch succession theory: Croton urucurana, Cecropia pachystachya, Cordia superba, Guazuma ulmifolia, Cytharexyllum myrianthum, Enterolobium contortisiliquum, Trema micrantha, Peltophorum dubium, Schinus terebinthifolius, Nectandra megapotamica. In conditions of high fragmentation of natural forests and high density of weeds, agroforestry systems may cause positive effects in riparian forests restoration, favoring better growing of native trees and lower costs of restoration.