A research report submitted to the Faculty of Science, University of Witwatersrand, in partial fulfillment of the requirements for the degree of Master of Science of the School of Animal Plant and Environmental Sciences Johannesburg, 3rd November 2017. / Only one tetraploid (four sets of chromosomes) species of baobab (Adansonia digitata, L.) was recognized on mainland Africa. However, a study published in 2012 reported the existence of a new diploid baobab species known as Adansonia kilima which was said to co-exist on mainland Africa with A. digitata. This new species was identified on the basis of morphology (mainly floral and stomatal features), ploidy level and molecular phylogenetics. The two species of African baobabs were also differentiated according to their elevation preferences of between 650 m –1500 m above sea level (a.s.l.) and below 800 m a.s.l. for A. kilima and A. digitata respectively, which were said to rarely overlap. The report of this new species and the need to accurately determine the exact number of species of baobabs existing on mainland Africa have brought about a renewed interest in the study of the African baobabs and have necessitated this study. This research therefore compared A. digitata and A. kilima to assess the latter’s authenticity as described by work. The objectives were to (i) examine floral and stomatal traits from samples across mainland African baobab populations to establish whether there are distinct differences that can be correlated with altitudinal differences in order to distinguish the species present in Africa, and (ii) use stomatal size and density to infer ploidy levels of baobabs that occur at low and high altitudes. Herbarium and fresh specimens of A. digitata and A. kilima from across Africa with both leaves and flowers were borrowed from various herbaria to represent the widespread distribution of baobab in Africa. Cluster analysis (CA), Principal Component Analysis (PCA) and Non-metric Multi-dimensional Scaling (NMDS) of seven floral traits of 124 African baobab specimens were used to analyze baobabs that occur at low or high altitude. These specimens did not form distinct clusters or separate groupings correlated with either low or high altitude. The inference of ploidy using stomatal size categories as per previous study showed no differences in ploidy level among the baobabs studied and the difference in morphological features between baobabs found at low and high altitudes also could not be linked to inferred differences in ploidy levels. Specimens were assigned diploids or tetraploids based on their stomatal length as defined by an earlier work and the altitude of each specimen was used to ascertain whether the ploidy level correspond to the altitudinal category reported by a study published in 2012. Box and whisker plots were also used to compare the floral (pollen grain diameter, volume and density) and stomatal traits of baobabs that occurred at low and high altitudes. There was no statistical difference in the variation in floral features among African mainland baobabs found at low and high altitudes except in staminal tube length and style length. The stomatal traits results reveal that the mean stomatal length and density (per 1000 μm2) between baobabs that occur at low and high altitudes were not statistically different except when mean stomatal length and density were grouped into the two putative ploidy categories as per previous study. Morphological features results suggest that the differences in floral size, and stomatal size and density of mainland African baobabs could be related to differences in climate, water availability and geographical variation. Based on the data analyzed for this work, it is concluded that A. kilima is not distinct enough from A. digitata, to be recognized as a new species. However, further research should investigate potential variation in genome size among African baobab that is correlated with altitude using flow cytometry analysis and/or chromosome counts. Key words: altitudinal variation, mainland African baobab, multivariate analysis, ploidy level, pollen grains, species concept, stomatal density, sympatric speciation. / LG2018

Made available in DSpace on 2014-06-12T17:39:27Z (GMT). No. of bitstreams: 2 arquivo6900_1.pdf: 804395 bytes, checksum: 60cf729f444ecbe1598ba9fed5ab11b9 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2002 / Este trabalho apresenta a implementação de uma técnica de modulação vetorial através da modulação escalar digital. A partir da escolha do valor de um parâmetro de controle determinado por software é possível que seja alterado o valor de aplicação dos tempos de roda livre, controlando assim os intervalos de tempo de fechamento das chaves no inversor trifásico. Esta técnica é implementada com o uso de contadores digitais, programados através de um FPGA que possibilita uma montagem mais simples e prática, o que implica em uma placa de interface digital (placa MLP) para geração de sinais modulados por largura de pulso apresentada de forma mais "enxuta", desenvolvida com o objetivo de promover a interface entre o microcomputador PC e o inversor trifásico. Por fim, são apresentados os resultados experimentais correspondentes a aplicação de testes na bancada de acionamentos, formada pelo conjunto inversos (inversor + retificador) onde são adquiridos os sinais de corrente de fase na saída do inversor

Doctor en Ciencias, Mención Computación / La cantidad y el uso de videos en Internet ha aumentado exponencialmente durante los últimos años. La investigación académica en tópicos de videos se ha desarrollado durante décadas, sin embargo la actual ubicuidad de los videos presiona por el desarrollo de nuevos y mejores algoritmos. Actualmente existen variadas necesidades por satisfacer y muchos problemas abiertos que requieren de investigación científica. En particular, la Detección de Copias de Video (DCV) aborda la necesidad de buscar los videos que son copia de un documento original. El proceso de detección compara el contenido de los videos en forma robusta a diferentes transformaciones audiovisuales. Esta tesis presenta un sistema de DCV llamado P-VCD, el cual utiliza algoritmos y técnicas novedosas para lograr alta efectividad y eficiencia. Esta tesis se divide en dos partes. La primera parte se enfoca en el estado del arte, donde se revisan técnicas comunes de procesamiento de imágenes y búsqueda por similitud, se analiza la definición y alcance de la DCV, y se presentan técnicas actuales para resolver este problema. La segunda parte de esta tesis detalla el trabajo realizado y sus contribuciones al estado del arte, analizando cada una de las tareas que componen esta solución, a saber: preprocesamiento de videos, segmentación de videos, extracción de características, búsqueda por similitud y localización de copias. En relación a la efectividad, se desarrollan las ideas de normalización de calidad de videos, descripción múltiple de contenidos, combinación de distancias, y uso de distancias métricas versus no-métricas. Como resultado se proponen las técnicas de creación automática de descriptores espacio-temporales a partir de descriptores de fotogramas, descriptores de audio combinables con descriptores visuales, selección automática de pesos, y distancia espacio-temporal para combinación de descriptores. En relación a la eficiencia, se desarrollan los enfoques de espacios métricos y tabla de pivotes para acelerar las búsquedas. Como resultado se proponen una búsqueda aproximada utilizando objetos pivotes para estimar y descartar distancias, búsquedas multimodales en grandes colecciones, y un índice que explota la similitud entre objetos de consulta consecutivos. Esta tesis ha sido evaluada usando la colección MUSCLE-VCD-2007 y participando en las evaluaciones TRECVID 2010 y 2011. El desempeño logrado en estas evaluaciones es satisfactorio. En el caso de MUSCLE-VCD-2007 se supera el mejor resultado publicado para esa colección, logrando la máxima efectividad posible, mientras que en el caso de TRECVID se obtiene una performance competitiva con otros sistemas del estado del arte.

Submitted by Rafael Santana (rafael.silvasantana@ufpe.br) on 2018-01-29T19:32:27Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertacao João Dionisio.pdf: 9976835 bytes, checksum: f1049a2c3bab2b464ac65b178e83ee23 (MD5) / Made available in DSpace on 2018-01-29T19:32:27Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertacao João Dionisio.pdf: 9976835 bytes, checksum: f1049a2c3bab2b464ac65b178e83ee23 (MD5) Previous issue date: 2016-09-30 / Em um cenário onde a evolução tecnológica e a disseminação da informação ocorrem em ciclos de tempo cada vez menores, novas tecnologias surgem, permitindo que as mensagens sejam transmitidas de maneira eletrônica. No ano de 2011, o projeto UFPEBooks foi criado com o objetivo de disponibilizar os livros lançados pela Editora Universitária e dessa forma introduzir a instituição no universo dos livros digitais, o que é vital para o crescimento da informação e do conhecimento na Universidade Federal de Pernambuco. Pensando na importância da interface nesse processo de relação com o usuário, o objetivo geral deste estudo foi avaliar sua usabilidade e a satisfação dos usuários, recorrendo a um conjunto de técnicas de avaliação destinadas a revelar potenciais fraquezas e assim contribuir para o aprimoramento do Projeto UFPEBooks, gerando, a partir da perspectiva de especialistas e do público-alvo, um conjunto de recomendações que servirão como ferramentas de auxílio aos profissionais responsáveis pelo desenvolvimento de livros-texto digitais. Os fundamentos teóricos e metodológicos foram embasados nos Princípios Ergonômicos de Bastien e Scapin. Foi observada a atividade de navegação de quinze participantes e em seguida foram colhidas opiniões através de um questionário de satisfação. Os resultados apontaram importantes efeitos da interface gráfica no desempenho de navegação. Ficou constatado que nem sempre a interface oferecia informações claras e explícitas ao leitor. Estes aspectos levantados, a partir do ponto de vista de especialistas e do público-alvo, tiveram o importante papel de gerar recomendações de forma a minimizar problemas ergonômicos e de usabilidade. / In a scenario where the technological development and the dissemination of information occurs in smaller and smaller time cycles, new technologies emerge enabling messages to be transmitted electronically. In 2011 the UFPEBooks project was created with the objective of providing the books published by the University Press departament and thus enter the institution in the world of digital books, which is vital to the growth of information and knowledge at the Federal University of Pernambuco. Given the importance of the interface in this relationship with the user process, the aim of this study was to evaluate its usability and user satisfaction, using a set of evaluation techniques to reveal potential weaknesses and thus contribute to the improvement of UFPEBooks project, generating, from the of experts and user’s perspective, a set of recommendations that will serve as support tools for professionals responsible for developing digital textbooks. The theoretical and methodological foundations were based on ergonomic principles of Bastien and Scapin. It was observed browsing activity of fifteen participants and then were collected opinions through a questionnaire of satisfaction. The results showed significant effects of the graphic interface in the navigation performance. It was found that not always the interface offered clear and explicit information to the reader. These raised issues, starting from the point of view of experts and the audience, had the important role of guiding recommendations in order to minimize ergonomic and usability problems.

Proverbs are one of the important oral literary genres in various cultures. Though in many societies and for a long time proverbs are regarded as succinct fixed artistic form, and authoritative which contain a general truth, wisdom and experience of the society and its creators are elders or anonymous, these characteristics are increasingly challenged today. This paper, therefore, intends to examine how Swahili literary writers and social network users participate in the creation and spread of Swahili modern proverbs in Tanzania. Data of this study were collected from Swahili literary works and websites. The findings reveal that the need to address and cope with today’s environment and change of worldview of the present generation are among the important factors to the emergence of the modern proverbs. It is also noted that modern Swahili proverbs are not only found among the Kiswahili literary writers and social network users, but also other people and avenues. / Methali ni moja ya utanzu muhimu wa fasihi simulizi katika tamaduni mbalimbali. Ingawa katika jamii nyingi na kwa muda mrefu methali zimekuwa zikichukuliwa kama usemi mfupi wa kisanaa, wenye mamlaka, ukweli, maarifa na tajiriba ya jamii, na watungaji wake ni wazee au hawajulikani, sifa hizi siku hizi zinazidi kudadisiwa. Makala hii, kwa hiyo, inalenga kuchunguza namna waandishi wa fasihi ya Kiswahili na watumiaji wa mitandao ya kijamii wanavyoshiriki katika uundaji na usambazaji wa methali za kileo za Kiswahili nchini Tanzania. Data za makala hii zilikusanywa kwa kupitia kazi mbalimbali za fasihi ya Kiswahili na kutembelea tovuti. Matokeo ya data yanaonesha kuwa haja ya kuakisi mazingira ya sasa na mabadiliko ya kimtazamo kwa kizazi cha leo ni miongoni mwa sababu zinazochangia katika kuibuka kwa methali za kileo. Aidha, methali za kileo za Kiswahili si tu zinapatikana miongoni mwa wanafasihi wa Kiswahili na watumiaji wa mitandao ya kijamii, bali pia zinatumika na watu na miktadha mbalimbali.

Proverbs are one of the important oral literary genres in various cultures. Though in many societies and for a long time proverbs are regarded as succinct fixed artistic form, and authoritative which contain a general truth, wisdom and experience of the society and its creators are elders or anonymous, these characteristics are increasingly challenged today. This paper, therefore, intends to examine how Swahili literary writers and social network users participate in the creation and spread of Swahili modern proverbs in Tanzania. Data of this study were collected from Swahili literary works and websites. The findings reveal that the need to address and cope with today’s environment and change of worldview of the present generation are among the important factors to the emergence of the modern proverbs. It is also noted that modern Swahili proverbs are not only found among the Kiswahili literary writers and social network users, but also other people and avenues. / Methali ni moja ya utanzu muhimu wa fasihi simulizi katika tamaduni mbalimbali. Ingawa katika jamii nyingi na kwa muda mrefu methali zimekuwa zikichukuliwa kama usemi mfupi wa kisanaa, wenye mamlaka, ukweli, maarifa na tajiriba ya jamii, na watungaji wake ni wazee au hawajulikani, sifa hizi siku hizi zinazidi kudadisiwa. Makala hii, kwa hiyo, inalenga kuchunguza namna waandishi wa fasihi ya Kiswahili na watumiaji wa mitandao ya kijamii wanavyoshiriki katika uundaji na usambazaji wa methali za kileo za Kiswahili nchini Tanzania. Data za makala hii zilikusanywa kwa kupitia kazi mbalimbali za fasihi ya Kiswahili na kutembelea tovuti. Matokeo ya data yanaonesha kuwa haja ya kuakisi mazingira ya sasa na mabadiliko ya kimtazamo kwa kizazi cha leo ni miongoni mwa sababu zinazochangia katika kuibuka kwa methali za kileo. Aidha, methali za kileo za Kiswahili si tu zinapatikana miongoni mwa wanafasihi wa Kiswahili na watumiaji wa mitandao ya kijamii, bali pia zinatumika na watu na miktadha mbalimbali.