This research was designed to investigate the fundamental nature in which blind people utilize audible cues to attend to their surroundings. Knowledge on how blind people respond to external spatial stimuli is expected to assist in development of better tools for helping people with visual disabilities navigate their environment. There was also interest in determining how blind people compare to sighted people in auditory localization tasks. The ability of sighted individuals, blindfolded individuals, and blind individuals in localizing spatial auditory targets was assessed. An acoustic display board allowed the researcher to provide multiple sound presentations to the subjects. The subjects’ responses in localization tasks were measured using a combination of kinematic head tracking and eye tracking hardware. Data was collected and analyzed to determine the ability of the groups in localizing spatial auditory targets. Significant differences were found among the three groups in spatial localization error and temporal patterns.

This thesis concerns blind source separation techniques using second order statistics and higher order statistics for reverberant environments. A focus of the thesis is algorithmic simplicity with a view to the algorithms being implemented in their online forms. The main challenge of blind source separation applications is to handle reverberant acoustic environments; a further complication is changes in the acoustic environment such as when human speakers physically move. A novel time-domain method which utilises a pair of finite impulse response filters is proposed. The method of principle angles is defined which exploits a singular value decomposition for their design. The pair of filters are implemented within a generalised sidelobe canceller structure, thus the method can be considered as a beamforming method which cancels one source. An adaptive filtering stage is then employed to recover the remaining source, by exploiting the output of the beamforming stage as a noise reference. A common approach to blind source separation is to use methods that use higher order statistics such as independent component analysis. When dealing with realistic convolutive audio and speech mixtures, processing in the frequency domain at each frequency bin is required. As a result this introduces the permutation problem, inherent in independent component analysis, across the frequency bins. Independent vector analysis directly addresses this issue by modeling the dependencies between frequency bins, namely making use of a source vector prior. An alternative source prior for real-time (online) natural gradient independent vector analysis is proposed. A Student's t probability density function is known to be more suited for speech sources, due to its heavier tails, and is incorporated into a real-time version of natural gradient independent vector analysis. The final algorithm is realised as a real-time embedded application on a floating point Texas Instruments digital signal processor platform. Moving sources, along with reverberant environments, cause significant problems in realistic source separation systems as mixing filters become time variant. A method which employs the pair of cancellation filters, is proposed to cancel one source coupled with an online natural gradient independent vector analysis technique to improve average separation performance in the context of step-wise moving sources. This addresses `dips' in performance when sources move. Results show the average convergence time of the performance parameters is improved. Online methods introduced in thesis are tested using impulse responses measured in reverberant environments, demonstrating their robustness and are shown to perform better than established methods in a variety of situations.

College students with visual disabilities are less likely to graduate than their sighted counterparts. The purpose of this study was to understand the life experiences of successful college students with visual disabilities. Concepts of risk and resiliency were used as a conceptual framework for understanding how people can have positive outcomes in spite of adversity. Individual, family, school, and community influences were explored. In-depth interviews were conducted with six participants who have vision impairments and were nearing the completion or had recently completed a college degree. Data were analyzed for common themes and meanings using a phenomenological method advanced by Moustakas (1994). Validity threats were minimized through triangulation, member checks, and thick data. Risk and protective factors in the context of family, school, and community for successful college students with visual disabilities were identified. Implications for rehabilitation counselors, college counselors, and special education teachers were discussed. Interventions to move students with visual disabilities toward resiliency and minimize the impact of risk factors that impede success were proposed. Suggestions for future research were offered.

Thanks to its ability to evaluate metabolic functions in tissues from the temporal evolution of a previously injected radiotracer, dynamic positron emission tomography (PET) has become an ubiquitous analysis tool to quantify biological processes. Several quantification techniques from the PET imaging literature require a previous estimation of global time-activity curves (TACs) (herein called \textit{factors}) representing the concentration of tracer in a reference tissue or blood over time. To this end, factor analysis has often appeared as an unsupervised learning solution for the extraction of factors and their respective fractions in each voxel. Inspired by the hyperspectral unmixing literature, this manuscript addresses two main drawbacks of general factor analysis techniques applied to dynamic PET. The first one is the assumption that the elementary response of each tissue to tracer distribution is spatially homogeneous. Even though this homogeneity assumption has proven its effectiveness in several factor analysis studies, it may not always provide a sufficient description of the underlying data, in particular when abnormalities are present. To tackle this limitation, the models herein proposed introduce an additional degree of freedom to the factors related to specific binding. To this end, a spatially-variant perturbation affects a nominal and common TAC representative of the high-uptake tissue. This variation is spatially indexed and constrained with a dictionary that is either previously learned or explicitly modelled with convolutional nonlinearities affecting non-specific binding tissues. The second drawback is related to the noise distribution in PET images. Even though the positron decay process can be described by a Poisson distribution, the actual noise in reconstructed PET images is not expected to be simply described by Poisson or Gaussian distributions. Therefore, we propose to consider a popular and quite general loss function, called the $\beta$-divergence, that is able to generalize conventional loss functions such as the least-square distance, Kullback-Leibler and Itakura-Saito divergences, respectively corresponding to Gaussian, Poisson and Gamma distributions. This loss function is applied to three factor analysis models in order to evaluate its impact on dynamic PET images with different reconstruction characteristics.

Em três experimentos realizou-se o mapeamento da mancha cega do olho direito para se investigar se o completamento perceptivo que ocorre nela distorce a percepção de tamanho de barras. Em todos os experimentos, o mapeamento da mancha cega foi realizada pelo método dos estímulos constantes; os tamanhos das barras podiam nunca interceptar a mancha cega, interceptá-la parcialmente ou interceptá-la por completo; e as barras eram apresentadas pelo método PEST para se determinar o ponto de igualdade subjetiva, e conseqüentemente, o erro constante. No Experimento I as barras eram horizontais e comparadas no nível do ponto de fixação em condição monocular com o olho direito. Elas eram apresentadas por 100, 300 ou 400 ms, aos pares, simultânea e simetricamente localizadas no hemicampo direito e esquerdo em relação ao ponto de fixação. Os resultados desse experimento indicaram uma assimetria lateral nas comparações de tamanho da barra menor e que o completamento perceptivo na mancha cega não distorce efetivamente o tamanho percebido. No Experimento II as barras eram verticais e podiam ser apresentadas também por 100, 300 ou 400 ms, aos pares, simultânea e simetricamente em relação ao ponto de fixação em cinco excentricidades nos hemicampos do olho direito em condição monocular. As barras nas excentricidades menor e maior não interceptavam a mancha cega e as barras de tamanhos maior e intermediário nas excentricidades intermediárias incidiam nas regiões periféricas e central da mancha cega. Os resultados indicaram também que o completamento perceptivo na mancha cega não distorce a percepção de tamanho e que em algumas excentricidades em que a barra padrão foi apresentada no hemicampo esquerdo evidencia-se uma assimetria lateral na comparação de tamanhos. No experimento III, o mapeamento da mancha cega do olho direito e as comparações das barras verticais foram realizados em condição dicótica. As barras foram apresentadas aos pares e seqüencialmente, expostas por 100 ms cada e com um intervalo de 200 ms entre suas apresentações. Elas foram apresentadas em cinco excentricidades no hemicampo direito de cada olho, similar ao Experimento II, de maneira que as comparações de tamanho envolvessem somente o hemisfério cerebral esquerdo. Os resultados indicaram também que o completamento perceptivo na mancha cega não distorce o tamanho percebido. Os três experimentos sugerem que existe assimetria ao se comparar tamanhos, embora tênue, quando se envolvem ambos hemisférios cerebrais e que a explicação associativa proposta por Trypathy et al. (1995) é a alternativa que melhor explica o completamento perceptivo na mancha cega. / Three experiments were carried out to investigate whether the filling-in in the blind spot can distort perceived size. In these experiments, the method of constant stimuli was applied to map the blind spot of the right eye; the lengths of the bars could never intercept the blind spot, intercept it partially or intercept it totally; and the PEST method was applied to determine the point of subjective equality, and then, the constant error. In Experiment I, the lengths of two horizontal bars were compared at the level of fixation point of the right eye under monocular viewing conditions. These bars were presented simultaneously for 100, 300 or 400ms and they were located symmetrically to each other from the fixation point. Results suggested that the filling-in in the blind spot did not distort perceived length, and that there was lateral asymmetry in comparing bars which lengths do not intercept the blind spot. In Experiment II, two vertical bars were presented simultaneously also for 100, 300 or 400ms and symmetrically from the fixation point at five eccentricities in the visual hemifields of right eye in monocular viewing conditions. Bars at the farther and closest eccentricity never intercepted the blind spot, and the bars at intermediate eccentricities could intercept the central and peripheral regions of the blind spot. Results also indicated that the filling-in in the blind spot did not distort perceived size, and that there was lateral asymmetry in comparing size as the standard bar was at the left visual hemifield. In Experiment III, the blind spot of the right eye was mapped and length bar comparisons were done in dichotic conditions in such way that only the left brain was involved. Two vertical bars were presented at five eccentricities like in Experiment II, but they were presented sequentially for 200 ms with an interval of 400 ms between presentations. Results also indicated that the filling-in did not affect perceived size. These three experiments suggest that there is a weak lateral asymmetry in size comparisons due to the inter-hemispheric brain effect and that the associative explanation proposed by Trypathy et al. (1995) is the best alternative to explain the filling-in in the blind spot.

Nesta tese analisamos e propomos métodos para a equalização não-treinada (cega) de canais de comunicação lineares FIR baseados em filtros de partículas, que são técnicas recursivas para a solução Bayesiana de problemas de filtragem estocástica. Iniciamos propondo novos métodos para equalização sob ruído gaussiano que prescindem do uso de codificação diferencial, ao contrário dos métodos existentes. Empregando técnicas de evolução artificial de parâmetros, estendemos estes resultados para o caso de ruído aditivo com distribuição não-gaussiana. Em seguida, desenvolvemos novos métodos baseados nos mesmos princípios para equalizar e decodificar conjuntamente sistemas de comunicação que empregam códigos convolucionais ou em bloco. Através de simulações numéricas, observamos que os algoritmos propostos apresentam desempenhos, medidos em termos de taxa média de erro de bit e velocidade de convergência, marcadamente superiores aos de métodos tradicionais, freqüentemente aproximando o desempenho dos algoritmos ótimos (MAP) treinados. Além disso, observamos que os métodos baseados em filtros de partículas determinísticos exibem desempenhos consistentemente superiores aos dos demais métodos, sendo portanto a melhor escolha caso o modelo de sinal empregado permita a marginalização analítica dos parâmetros desconhecidos do canal. / In this thesis, we propose and analyze blind equalization methods suitable for linear FIR communications channels, focusing on the development of algorithms based on particle filters - recursive methods for approximating Bayesian solutions to stochastic filtering problems. Initially, we propose new equalization methods for signal models with gaussian additive noise that dispense with the need for differentially encoding the transmitted signals, as opposed to the previously existing methods. Next, we extend these algorithms to deal with non-gaussian additive noise by deploying artificial parameter evolution techniques. We next develop new joint blind equalization and decoding algorithms, suitable for convolutionally or block-coded communications systems. Via numerical simulations we show that the proposed algorithms outperform traditional approaches both in terms of mean bit error rate and convergence speed, and closely approach the performance of the optimal (MAP) trained equalizer. Furthermore, we observed that the methods based on deterministic particle filters consistently outperform those based on stochastic approaches, making them preferable when the adopted signal model allows for the analytic marginalization of the unknown channel parameters.

Em três experimentos realizou-se o mapeamento da mancha cega do olho direito para se investigar se o completamento perceptivo que ocorre nela distorce a percepção de tamanho de barras. Em todos os experimentos, o mapeamento da mancha cega foi realizada pelo método dos estímulos constantes; os tamanhos das barras podiam nunca interceptar a mancha cega, interceptá-la parcialmente ou interceptá-la por completo; e as barras eram apresentadas pelo método PEST para se determinar o ponto de igualdade subjetiva, e conseqüentemente, o erro constante. No Experimento I as barras eram horizontais e comparadas no nível do ponto de fixação em condição monocular com o olho direito. Elas eram apresentadas por 100, 300 ou 400 ms, aos pares, simultânea e simetricamente localizadas no hemicampo direito e esquerdo em relação ao ponto de fixação. Os resultados desse experimento indicaram uma assimetria lateral nas comparações de tamanho da barra menor e que o completamento perceptivo na mancha cega não distorce efetivamente o tamanho percebido. No Experimento II as barras eram verticais e podiam ser apresentadas também por 100, 300 ou 400 ms, aos pares, simultânea e simetricamente em relação ao ponto de fixação em cinco excentricidades nos hemicampos do olho direito em condição monocular. As barras nas excentricidades menor e maior não interceptavam a mancha cega e as barras de tamanhos maior e intermediário nas excentricidades intermediárias incidiam nas regiões periféricas e central da mancha cega. Os resultados indicaram também que o completamento perceptivo na mancha cega não distorce a percepção de tamanho e que em algumas excentricidades em que a barra padrão foi apresentada no hemicampo esquerdo evidencia-se uma assimetria lateral na comparação de tamanhos. No experimento III, o mapeamento da mancha cega do olho direito e as comparações das barras verticais foram realizados em condição dicótica. As barras foram apresentadas aos pares e seqüencialmente, expostas por 100 ms cada e com um intervalo de 200 ms entre suas apresentações. Elas foram apresentadas em cinco excentricidades no hemicampo direito de cada olho, similar ao Experimento II, de maneira que as comparações de tamanho envolvessem somente o hemisfério cerebral esquerdo. Os resultados indicaram também que o completamento perceptivo na mancha cega não distorce o tamanho percebido. Os três experimentos sugerem que existe assimetria ao se comparar tamanhos, embora tênue, quando se envolvem ambos hemisférios cerebrais e que a explicação associativa proposta por Trypathy et al. (1995) é a alternativa que melhor explica o completamento perceptivo na mancha cega. / Three experiments were carried out to investigate whether the filling-in in the blind spot can distort perceived size. In these experiments, the method of constant stimuli was applied to map the blind spot of the right eye; the lengths of the bars could never intercept the blind spot, intercept it partially or intercept it totally; and the PEST method was applied to determine the point of subjective equality, and then, the constant error. In Experiment I, the lengths of two horizontal bars were compared at the level of fixation point of the right eye under monocular viewing conditions. These bars were presented simultaneously for 100, 300 or 400ms and they were located symmetrically to each other from the fixation point. Results suggested that the filling-in in the blind spot did not distort perceived length, and that there was lateral asymmetry in comparing bars which lengths do not intercept the blind spot. In Experiment II, two vertical bars were presented simultaneously also for 100, 300 or 400ms and symmetrically from the fixation point at five eccentricities in the visual hemifields of right eye in monocular viewing conditions. Bars at the farther and closest eccentricity never intercepted the blind spot, and the bars at intermediate eccentricities could intercept the central and peripheral regions of the blind spot. Results also indicated that the filling-in in the blind spot did not distort perceived size, and that there was lateral asymmetry in comparing size as the standard bar was at the left visual hemifield. In Experiment III, the blind spot of the right eye was mapped and length bar comparisons were done in dichotic conditions in such way that only the left brain was involved. Two vertical bars were presented at five eccentricities like in Experiment II, but they were presented sequentially for 200 ms with an interval of 400 ms between presentations. Results also indicated that the filling-in did not affect perceived size. These three experiments suggest that there is a weak lateral asymmetry in size comparisons due to the inter-hemispheric brain effect and that the associative explanation proposed by Trypathy et al. (1995) is the best alternative to explain the filling-in in the blind spot.

Com a finalidade de melhorar o desempenho e de entender os atletas, atualmente tem aumentado a utilização de métodos de avaliação psicológica, os quais chegaram ao esporte e passaram a ocupar espaço nos planejamentos de equipes, auxiliando na tomada de decisões relacionadas ao desempenho esportivo. A Escala de Humor de Brunel (BRUMS) avalia a disposição mental e o humor do indivíduo, contribuindo para a individualização do treinamento. O objetivo desta pesquisa foi o de relacionar estas subescalas de estados de humor ao desempenho esportivo de 30 jogadores profissionais de Goalball no período de treinamento e competição (jogo) estratificados por sexo, nível competitivo, posição e titularidade. Os resultados demonstraram correlações significativas entre variáveis de humor e de desempenho esportivo nas situações de treino e jogo, destacaram as diferenças de estados de humor entre os sexos, porém não no desempenho, demonstraram que não existem diferenças significativas no desempenho esportivo de atletas de nível nacional e internacional, que a posição de ala possui característica ofensiva e a de pivô, defensiva, e ainda que atletas reservas não diferem no desempenho esportivo, porém diferem nos estados de humor quanto aos titulares. Pode-se concluir que se faz necessária avaliação constante dos estados de humor juntamente com o desempenho esportivo para que se obtenha o melhor rendimento de cada atleta / Sports performance improvement depends on athletes behavior in training and competition situations. Several methods of psychological assessment are used on sports teams, helping coaches and team staffs make decisions about players conditions and their performance enhancement. Brunel\'s Mood Scale (BRUMS) evaluates individual mental and mood states, which may lead to training and periodization changes on sports performance. The aim of this study was to relate these mood scales to sport performance of 30 professional Goalball players during training and competition, stratified by sex, competitive level, position and ownership. The results demonstrated significant correlations among mood and sport performance variables in training and competition, highlighted the differences in mood states between men and women but not in performance, showed that national and international players do not differ regarding athletic performance, indicated that that wing players tend to attack more than defend while pivots tend to defend more than attack and finally revealed that reserves differ from holders in mood states but do not differ from holders regarding sport performance. It can be concluded that it is important to evaluate mood states of athletes as a way to enhance sports performance

Made available in DSpace on 2016-04-25T20:19:54Z (GMT). No. of bitstreams: 1 Angelica Aparecida de Oliveira Bicalho.pdf: 2182488 bytes, checksum: b4cdc8123c053def10bb8bd82a5f4f0c (MD5) Previous issue date: 2010-10-14 / One of the characteristics of contemporary society is the validation of the functions and attributes of image: looking, viewing and seeing can be considered as a hyper-cognization of vision. To move from the behavior of those who are able to see and those who are blind can mean much more than the contrasts between seeing and not seeing, between light and dark, or other antinomies. Anthropological studies based only on what is explicit, what is visible, and what can be observed are able to exacerbate differences and be represented as poor guides of what people do, know, or think. However, blind individuals have been the object of systematic studies, as carriers of special needs or in the condition of a minority to be included. Although the term carriers of special needs is a traditionally accepted way to refer to a social group, without the label of handicap , it is not self-clarifying, for, if considered individually, everyone presents specific, special needs. The eyes, blindness and vision were analyzed under the perspective of science and mythology. The aim of this work is to enter the sea of blindness without stereotypes, that is, to attempt to understand the invisible and lacunary universe of thought in which the blind person is located and the sensitive and relatively continuous world the visible world represented by the screen. For this work, we have analyzed two movies: Blindness and Red Like the Sky and the documentary Janela da alma [Window of the Soul]. University students from the São Gabriel campus, from PUC Minas, were census-like surveyed in order to identify those blind and carrier of low vision, who presented their perspective in relation to the seventh art / A sociedade contemporânea tem como uma de suas características a valorização das funções e atributos da imagem: o olhar, a visão e o enxergar, podem ser considerados como uma hiper-cognização da visão. Transitar entre o comportamento das pessoas que enxergam e o das cegas pode significar muito além dos contrastes entre ver e não ver, entre claro e escuro, ou outras antinomias. Estudos antropológicos baseados apenas no que é explícito, no que é visível, e no que pode ser observado podem exacerbar diferenças e se configurar como guias pobres sobre o que as pessoas fazem, sabem ou pensam. A pessoa cega tem sido objeto de estudos sistemáticos, porém, como portadora de necessidades especiais ou na sua condição de minoria a ser incluída. Embora a terminologia portadores de necessidades especiais seja uma forma tradicionalmente aceita para se referenciar a um grupo social sem a pecha de deficiente, ela não é auto-esclarecedora, pois se consideradas individualmente, todas as pessoas apresentam necessidades específicas, especiais. Penetrar no mar da cegueira sem estereótipos é a proposta deste trabalho: tentar entender o universo do pensamento invisível e lacunar no qual a pessoa cega se situa e o mundo sensível e relativamente contínuo o mundo visível representado pela tela. Os olhos, a cegueira e a visão foram analisados sob a perspectiva da ciência e da mitologia. Foram analisadas as películas Ensaio sobre a cegueira, Vermelho como o céu e o documentário Janela da alma. Foram entrevistados de forma censitária os alunos da Unidade São Gabriel, da PUC Minas para levantar a identificação dos universitários cegos e portadores de baixa visão, que apresentaram sua perspectiva em relação à sétima arte

Made available in DSpace on 2016-04-26T14:52:35Z (GMT). No. of bitstreams: 1 Angelica Aparecida de Oliveira Bicalho.pdf: 2182488 bytes, checksum: b4cdc8123c053def10bb8bd82a5f4f0c (MD5) Previous issue date: 2010-10-14 / One of the characteristics of contemporary society is the validation of the functions and attributes of image: looking, viewing and seeing can be considered as a hyper-cognization of vision. To move from the behavior of those who are able to see and those who are blind can mean much more than the contrasts between seeing and not seeing, between light and dark, or other antinomies. Anthropological studies based only on what is explicit, what is visible, and what can be observed are able to exacerbate differences and be represented as poor guides of what people do, know, or think. However, blind individuals have been the object of systematic studies, as carriers of special needs or in the condition of a minority to be included. Although the term carriers of special needs is a traditionally accepted way to refer to a social group, without the label of handicap , it is not self-clarifying, for, if considered individually, everyone presents specific, special needs. The eyes, blindness and vision were analyzed under the perspective of science and mythology. The aim of this work is to enter the sea of blindness without stereotypes, that is, to attempt to understand the invisible and lacunary universe of thought in which the blind person is located and the sensitive and relatively continuous world the visible world represented by the screen. For this work, we have analyzed two movies: Blindness and Red Like the Sky and the documentary Janela da alma [Window of the Soul]. University students from the São Gabriel campus, from PUC Minas, were census-like surveyed in order to identify those blind and carrier of low vision, who presented their perspective in relation to the seventh art / A sociedade contemporânea tem como uma de suas características a valorização das funções e atributos da imagem: o olhar, a visão e o enxergar, podem ser considerados como uma hiper-cognização da visão. Transitar entre o comportamento das pessoas que enxergam e o das cegas pode significar muito além dos contrastes entre ver e não ver, entre claro e escuro, ou outras antinomias. Estudos antropológicos baseados apenas no que é explícito, no que é visível, e no que pode ser observado podem exacerbar diferenças e se configurar como guias pobres sobre o que as pessoas fazem, sabem ou pensam. A pessoa cega tem sido objeto de estudos sistemáticos, porém, como portadora de necessidades especiais ou na sua condição de minoria a ser incluída. Embora a terminologia portadores de necessidades especiais seja uma forma tradicionalmente aceita para se referenciar a um grupo social sem a pecha de deficiente, ela não é auto-esclarecedora, pois se consideradas individualmente, todas as pessoas apresentam necessidades específicas, especiais. Penetrar no mar da cegueira sem estereótipos é a proposta deste trabalho: tentar entender o universo do pensamento invisível e lacunar no qual a pessoa cega se situa e o mundo sensível e relativamente contínuo o mundo visível representado pela tela. Os olhos, a cegueira e a visão foram analisados sob a perspectiva da ciência e da mitologia. Foram analisadas as películas Ensaio sobre a cegueira, Vermelho como o céu e o documentário Janela da alma. Foram entrevistados de forma censitária os alunos da Unidade São Gabriel, da PUC Minas para levantar a identificação dos universitários cegos e portadores de baixa visão, que apresentaram sua perspectiva em relação à sétima arte