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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.
591

The 'convergence of the twain' : a notational analysis of Northern Hemisphere rugby league and rugby union football 1988-2002

Eaves, Simon John January 2006 (has links)
The principal aim of this study was to create longitudinal profiles (1988-2002) for the games of rugby union and rugby league football in order to identify whether changes in time, offence, defence and game action variables, and positional and game performance indicators were a reflection that the two codes of rugby were 'converging'. Anecdotal evidence had suggested that due to certain administrative developments within this time frame many facets of the two games were becoming similar, thereby spawning the notion of a future single, unified game of 'rugby'. This thesis presents the first empirical and objective assessment of whether such convergence has occurred. The data for this study were extracted from 48 video-taped recordings of First Grade rugby league and International rugby union in the Northern hemisphere over the specified time frame. The matches were identifiable by Era (pre-/post-professional) and Period (1988-92, 1993-95, 1997-99 and2000-02). Key aspects of play or performance were distinguished via game models and expert opinion and were scrutinised via a series of specifically designed and validated hand notation systems. Initial analysis considered (and established) the reliability of these systems, thereafter parametric and non-parametric inferential statistical teohniques were employed to identify Era and Period effects within each Code, with the additional analyses to consider the effects of Game Result and Game Quarter Outcomes. The findings from these analyses, particulaily the observed increase in ball in play time, changes at the ruck, maul, and lineout, and alterations in defence patterns of play, have provided a strong argument that the two Codes underwent a discernable degree of convergence over the years being considered. It was concluded that the introduction of professional playing status (rugby union), the summer playing season (rugby league), and law changes were likely causes of the two games being now similar in many respects. Although additional analyses should be encouraged to corroborate the present findings, the case for the development of a single Code of rugby can now be made.
592

Ocular accommodation control and adaptive optics : the development of monocular and binocular adaptive optics instrumentation for the study of accommodation and convergence, and study of the monocular accommodative response to rapid changes in dioptric stimuli

Curd, Alistair Paul January 2014 (has links)
The relationship between accommodation and myopia has been under investigation for many years, and the effort to understand it is ongoing. In this thesis, an introduction to the state of myopia research is given first, with particular reference to studies of accommodation and higher-order ocular aberrations, which feature in the subsequent chapters. Following a brief introduction to the general technique of aberrometry and visual stimulus control using adaptive optics, the development of a monocular adaptive optics instrument for this purpose is described. The instrument is used to vary a dioptric stimulus and record the accommodation response in pilot studies and a detailed experiment, which has also been published elsewhere. It is found, among other things, that accommodation can respond to more than one different input level during its latency period, and that such inputs can be stored until components of the accommodation control system are free to process them. Indications of a minimum halting time for accommodation, of around 0.6 s, are presented. In later chapters, the development and testing of a new, binocular adaptive optics apparatus will be found. As well as binocular aberrometry and adaptive optics control of stimulus aberrations, this instrument displaces images to allow for and stimulate ocular convergence in binocular accommodation experiments. It is the first instrument in the world with its combined functionalities. Finally, the contribution of this thesis is summarised, and further instrumentation development and experiments are put forward for the continuation of this branch of accommodation and myopia research.
593

Evolutionary many-objective optimisation : pushing the boundaries

Li, Miqing January 2015 (has links)
Many-objective optimisation poses great challenges to evolutionary algorithms. To start with, the ineffectiveness of the Pareto dominance relation, which is the most important criterion in multi-objective optimisation, results in the underperformance of traditional Pareto-based algorithms. Also, the aggravation of the conflict between proximity and diversity, along with increasing time or space requirement as well as parameter sensitivity, has become key barriers to the design of effective many-objective optimisation algorithms. Furthermore, the infeasibility of solutions' direct observation can lead to serious difficulties in algorithms' performance investigation and comparison. In this thesis, we address these challenges, aiming to make evolutionary algorithms as effective in many-objective optimisation as in two- or three-objective optimisation. First, we significantly enhance Pareto-based algorithms to make them suitable for many-objective optimisation by placing individuals with poor proximity into crowded regions so that these individuals can have a better chance to be eliminated. Second, we propose a grid-based evolutionary algorithm which explores the potential of the grid to deal with many-objective optimisation problems. Third, we present a bi-goal evolution framework that converts many objectives of a given problem into two objectives regarding proximity and diversity, thus creating an optimisation problem in which the objectives are the goals of the search process itself. Fourth, we propose a comprehensive performance indicator to compare evolutionary algorithms in optimisation problems with various Pareto front shapes and any objective dimensionality. Finally, we construct a test problem to aid the visual investigation of evolutionary search, with its Pareto optimal solutions in a two-dimensional decision space having similar distribution to their images in a higher-dimensional objective space. The work reported in this thesis is the outcome of innovative attempts at addressing some of the most challenging problems in evolutionary many-objective optimisation. This research has not only made some of the existing approaches, such as Pareto-based or grid-based algorithms that were traditionally regarded as unsuitable, now effective for many-objective optimisation, but also pushed other important boundaries with novel ideas including bi-goal evolution, a comprehensive performance indicator and a test problem for visual investigation. All the proposed algorithms have been systematically evaluated against existing state of the arts, and some of these algorithms have already been taken up by researchers and practitioners in the field.
594

Macroeconomic convergence in SACU : a panel unit root analysis

04 October 2010 (has links)
M.Comm. / This study uses annual data for five SACU members over the period 1991-2005 to investigate the evidence for convergence in macroeconomic variables. Panel unit root test as an econometric tool is utilised together with other several approaches for this analysis. The results show significant evidence that the SACU countries have reached a reasonable level of convergence on specific macroeconomic variables. This can be attributed to common economic policies and institutional features. It is also evident that the countries that are members of the CMA show a dramatically higher convergence rate. As far as monetary policy is concerned, a high degree of convergence has been achieved in SACU. However, the results show no convergence on fiscal policies. This could be attributed to data constraint on debt to GDP which was used as a proxy for fiscal policy.
595

Comparison of Power Flow Algorithms for inclusion in On-line Power Systems Operation Tools

Bokka, Naveen 17 December 2010 (has links)
The goal of this thesis is to develop a new, fast, adaptive load flow algorithm that "automatically alternates" numerical methods including Newton-Raphson method, Gauss-Seidel method and Gauss method for a load flow run to achieve less run time. Unlike the proposed method, the traditional load flow analysis uses only one numerical method at a time. This adaptive algorithm performs all the computation for finding the bus voltage angles and magnitudes, real and reactive powers for the given generation and load values, while keeping track of the proximity to convergence of a solution. This work focuses on finding the algorithm that uses multiple numerical techniques, rather than investigating programming techniques and programming languages. The convergence time is compared with those from using each of the numerical techniques. The proposed method is implemented on the IEEE 39-bus system with different contingencies and the solutions obtained are verified with PowerWorld Simulator, a commercial software for load flow analysis.
596

Phylogenetic Relationships and Evolution of Snakes

Figueroa, Alex 10 August 2016 (has links)
Snakes represent an impressive evolutionary radiation of over 3,500 widely-distributed species, categorized into 515 genera, encompassing a diverse range of morphologies and ecologies. This diversity is likely attributable to their distinctive morphology, which has allowed them to populate a wide range of habitat types within most major ecosystems. In my first chapter, I provide the largest-yet estimate of the snake tree of life using maximum likelihood on a supermatrix of 1745 taxa (1652 snake species + 7 outgroup taxa) and 9,523 base pairs from 10 loci (5 nuclear, 5 mitochondrial), including previously unsequenced genera (2) and species (61). I then use this phylogeny to test hypotheses regarding heterogeneity in diversification rates and how this shaped overall patterns of snake diversity in Chapter 2. I also used the species-level phylogeny to test the evolution of habitat use in snakes, morphological variation, and whether distantly-related species exhibit morphological convergence in Chapter 3. Finally, in Chapter 4 I investigate how prehensile tails effect striking performance in arboreal snakes.
597

Business cycle convergence in EMU: A first look at the second moment

Crespo Cuaresma, Jesus, Fernandez-Amador, Octavio 09 1900 (has links) (PDF)
We propose the analysis of the dynamics of the standard deviation of business cycles across euro area countries in order to evaluate the patterns of cyclical convergence in the European Monetary Union for the period 1960-2008. We identify significant business cycle divergence taking place in the mid-eighties, followed by a persistent convergence period spanning most of the nineties. This convergent episode finishes roughly with the birth of the European Monetary Union. We show that a hypothetical euro area including all the new members of the recent enlargement rounds does not imply a sizeable decrease in the optimality of the currency union. Finally, the European synchronization differential with respect to other developed economies seems to have been diluted within a global cycle since 2004.
598

Komentář za minutu pohledem komentátorů Hospodářských novin / Komentář za minutu by publicists of Hospodářské noviny

Rizikyová, Markéta January 2019 (has links)
The thesis aims to examine the 'Komentář za minutu' format, published by the online offshoot of 'Hospodářské noviny' daily from November 2014 to January 2017. The theoretical part brings forward the Economia publishing house in context of corporate convergence, as well as attributes of comment genres, online videos, and particularities of audio-visual instruments. The practical part qualitatively analyses data acquired by interviews with journalists of 'Hospodářské noviny' daily who featured in Komentář za minutu. All interviews are included.
599

Evolução da margem do manto em Pteriomorphia (Mollusca: Bivalvia): um modelo para compreensão da macroecologia do bentos marinho / Evolution of the mantle margin in Pteriomorphia (Mollusca: Bivalvia): insights into the macroecology of the marine benthos

Audino, Jorge Alves 31 May 2019 (has links)
Nos moluscos da classe Bivalvia, a margem do manto (ou palial) é geralmente organizada em três pregas e representa um ponto chave na compreensão da irradiação evolutiva do grupo e na conquista de novos nichos ecológicos. Na subclasse Pteriomorphia, agrupamento que reúne bivalves como ostras, vieiras e mexilhões, a margem do manto é amplamente diversa. Além disso, algumas linhas de evidência apontam para a associação entre estruturas paliais e diversificação de hábitos de vida, de modo que essa região anatômica representa uma importante fonte de dados para estudos de adaptação e correlação fenótipo-ambiente. A pesquisa desenvolvida investigou a diversidade morfológica da margem do manto em Pteriomorphia, por meio de abordagens comparativas e funcionais, a fim de inferir a evolução dessa região anatômica e testar hipóteses de homologia, convergência e correlação. A metodologia abrangeu: (1) inferência filogenética de Pteriomorphia com base em 187 espécies e até cinco genes; (2) morfologia comparada de 209 espécies utilizando-se espécimes depositados em coleções científicas, levantamento de caracteres chave do manto e emprego de métodos filogenéticos comparativos; e (3) anatomia detalhada da margem do manto em representantes de 12 espécies das principais famílias de Pteriomorphia, que foram coletados e analisados por meio de histologia, microscopia eletrônica de varredura e microscopia confocal. A análise filogenética de Pteriomorphia indica que o grupo é monofilético e organizado em quatro ordens contidas em dois clados principais (Arcida+Pectinida e Ostreida+Mytilida). A evolução da margem do manto abrange o surgimento de cinco tipos de órgãos fotorreceptores em diferentes linhagens epifaunais, com subsequente perda desses órgãos principalmente em grupos que se tornaram infaunais. Convergências evolutivas foram recorrentes na irradiação dos Pteriomorphia, como é o caso dos tentáculos paliais. Algumas dessas convergências estão correlacionadas a transições para o hábito de vida infaunal, como demonstrado pela hipertrofia da prega interna do manto em representantes de Arcida e Mytilida. A caracterização da inervação, musculatura, atividade secretora e ciliação da margem do manto contribuiu para a compreensão da anatomia funcional das pregas, ocelos, tentáculos, glândulas e demais estruturas associadas. Em suma, os resultados obtidos permitem compreender a evolução da margem do manto em Pteriomorphia associada a mudanças nos hábitos de vida, fornecendo evidências importantes para se explorar questões macroecológicas na irradiação dos bivalves e do bentos marinho como um todo / The mantle margin in bivalve mollusks typically comprises three folds, being considered a key element in the evolutionary radiation of the class and occupancy of novel ecological niches. In the subclass Pteriomorphia, which includes oysters, scallops, and mussels, the mantle margin is significantly diverse. In addition, several lines of evidence suggest the association between mantle structures and diversification of lifestyles, making the mantle margin a suitable anatomical region for studies focused on adaptations and phenotype-environment correlations. The present investigation evaluated the morphological diversity of the mantle margin in Pteriomorphia, by means of comparative and functional approaches, to infer the evolution of this anatomical region, and test hypotheses of homology, convergence and correlation. The methodology included: (1) phylogenetic inference of Pteriomorphia based on 187 taxa and up to five genes; (2) comparative morphology of 209 species based on observations of archived specimens, survey of key mantle traits and subsequent use of phylogenetic comparative methods; and (3) detailed anatomy of the mantle margin in representatives of 12 species from the most diverse pteriomorphian families, which were collected and analyzed by means of histology, scanning electron microscopy and confocal microscopy. Phylogenetic analyses of Pteriomorphia corroborate its monophyly and indicate it is comprised of four orders divided in two main clades (Arcida+Pectinida and Ostreida+Mytilida). The inferred evolution of the mantle margin suggests the origin of five types of photoreceptor organs in independent epifaunal lineages, with subsequent loss of eyespots mostly in groups that became infaunal. Evolutionary convergences were pervasive in pteriomorphian radiation, as illustrated by multiple gains of mantle tentacles. Some convergences are correlated with transitions to infaunal lifestyles, as demonstrated by the hypertrophy of the inner mantle fold in lineages within Arcida and Mytilida. In addition, the detailed investigation of musculature, innervation, secretory activity and cilia of the mantle margin permitted inferring possible functions performed by mantle folds, eyespots, tentacles, glands and further associated structures. Altogether, the results shed light on the evolution of the mantle margin in Pteriomorphia in association with lifestyle shifts, therefore providing bases to explore macroecological questions in the evolutionary radiation of bivalves and the marine benthos as a whole
600

O efeito das condutâncias dependentes de voltagem e de glutamato nas respostas à luz da célula bipolar ligada a bastonetes: um estudo computacional / Not informed by the author

Leopoldo, Kaê 09 February 2017 (has links)
O sistema visual lida com mudanças significativas na quantidade absoluta de fótons no meio ambiente, que varia 10 a 12 unidades logarítmicas ao longo de um dia. Parte desta versatilidade decorre da existência de fotorreceptores, bastonetes e cones, ativos em luminosidades médias diferentes, e outra parte é consequência de mecanismos de controle de ganho pós-receptorais, que ajustam a faixa dinâmica da retina à luminosidade média. Já na primeira sinapse visual, a atividade de muitos fotorreceptores converge para as células bipolares (BCs), neurônios de segunda ordem. Em mamíferos, supõe-se que o número de neurônios convergentes mantém-se relativamente fixo durante a vida adulta do organismo, embora a árvore dendrítica das BCs aumente de tamanho. No caso de peixes teleósteos, o grau de convergência neuronal para as BCs aumenta com a idade em função de neurogênese e sinaptogênese constantes. Como a relação entre a estrutura celular e o grau de convergência sináptica influencia a integração somática de sinais, estudamos os efeitos do crescimento celular acompanhado de variações na convergência sináptica no caso específico da BC ligada a bastonetes. Para tanto, desenvolvemos um modelo computacional deste tipo celular e dos bastonetes a ela conectados utilizando o ambiente de simulação NEURON, com base em dados de literatura e obtidos por nosso grupo de pesquisa a respeito de sua geometria, conectividade e biofísica, e simulamos diversos tipos de estimulação. Para mimetizar níveis escotópicos de luminosidade, estimulamos apenas um dos bastonetes convergindo para a BC modelo; para mimetizar níveis mesópicos, todos os bastonetes foram estimulados concomitantemente. Estas simulações foram realizadas primeiramente com um modelo de BC contendo apenas condutâncias sinápticas e passivas, para investigar o impacto da geometria celular na integração de sinais. A seguir, o modelo passou a incorporar condutâncias dependentes de voltagem permeáveis a potássio (K+) modeladas a partir de dados da literatura e do nosso grupo de pesquisa, para investigar o papel das mesmas no controle de ganho da sinapse entre BCs e bastonetes durante o crescimento celular. Os resultados destas simulações indicam que o aumento da árvore dendrítica da BC com o crescimento hiperpolariza seu potencial de repouso e aumenta as amplitudes de resposta, devido ao aumento da área de superfície de membrana contendo canais passivos com potencial de reversão negativo. Já o aumento da convergência de bastonetes para a BC despolariza seu potencial de repouso e diminui as amplitudes resposta, o que equivaleria a uma diminuição da sensibilidade 3 em células reais. Mais ainda, o aumento no grau de convergência contribui para a diminuição das latências de resposta da BC, ao passo que o crescimento celular aumenta as latências linearmente. A inserção de canais dependentes de voltagem nos terminais dendríticos da BC aproxima as amplitudes e diminui as latências de resposta de BCs com diferentes graus de convergência. Além disso, tais canais reduzem os efeitos decorrentes do crescimento celular descritos anteriormente, tornando a amplitude e latência de resposta independentes do tamanho da árvore dendrítica. Desse modo, canais de K+ dependentes de voltagem dendríticos estabilizam as amplitudes e latências de resposta da BC ao longo do crescimento, contribuindo para a coerência da mensagem passada para as outras camadas da retina e, posteriormente, para o cérebro. Estes resultados sugerem que correntes ativas são fundamentais não apenas para controlar o ganho das sinapses entre bastonetes e BCs em um mesmo estado de adaptação, mas também para estabilizar o potencial de repouso e velocidade e amplitudes de resposta dos neurônios ao longo do crescimento / The visual system deals with significant changes in the absolute quantity of photons in the environment, which vary 10 to 12 log units throughout a single day. Part of this versatility is due to the existence of different photoreceptors, rods and cones, which function at different mean light intensities, and due to post-receptor gain control mechanisms, which adjust the dynamic range of the retina to the mean luminosity. At the first visual synapse, the activity of many photoreceptors converges onto bipolar cells (BCs), second order neurons of the retina. In mammals, the degree of convergence is supposed to be constant throughout adult life, despite evidence of morphological changes in the dendritic structure of BCs. In teleost fish, however, the convergence of rods to BCs increases with age due to constant retinal neurogenesis and synaptogenesis. Since cellular structure and synaptic convergence influence somatic signal integration, we investigated the effects of cellular growth and synaptic convergence in the responses of the rod bipolar cell. We developed a computational model of a BC-rod circuitry within the NEURON simulation environment, based on literature data and on data collected by our own research group regarding the geometry, connectivity and biophysics of BCs. To simulate scotopic light levels, only one of the rods converging to the model BC was stimulated. Mesopic light levels were simulated by concomitantly stimulating all rods. We initially investigated the impact of cell geometry in somatic signal integration, by studying a model BC containing only passive and synaptic conductances. We subsequently inserted a voltage-gated potassium (K+) conductance in the dendritic tips of the model in order to investigate its role in controlling the gain of the rod-BC synapse during growth. Our results indicate that increasing the dendritic tree leads to hyperpolarization of the BC resting potential, due to the larger membrane surface containing the passive conductance, which has a negative reversal potential. Increasing rod convergence, on the other hand, depolarizes the BC resting potential and decreases response amplitudes, which would be equivalent to a decrease in sensitivity in a real cell. In addition, increases in convergence reduce response latencies, whereas cellular growth increases latencies linearly. The insertion of voltage-gated K+ conductances in the dendritic tips of the BC, in turn, aproximates the response amplitudes and decreases response latencies of BCs with different synaptic convergences. Moreover, voltage-gated conductances reduce the consequences of cellular growth, rendering response amplitudes and latencies independent of dendritic 5 tree size. These active conductances therefore contribute to signal consistency. Our results suggest that active currents not only control the gain of the rod-BC synapse in a given adaptive state, but also stabilize the BC resting potential, as well as response amplitude and latency during growth

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