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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.
321

Laser-acupuntura adjuvante à terapia oclusal reversível: um ensaio clínico controlado em pacientes com desordens temporomandibulares

Ferreira, Luciano Ambrosio 25 March 2011 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-13T19:49:00Z No. of bitstreams: 1 lucianoambrosioferreira.pdf: 3321721 bytes, checksum: 8aa6e24d8b24fa74ffa52a7b23803d30 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-07-14T10:37:04Z (GMT) No. of bitstreams: 1 lucianoambrosioferreira.pdf: 3321721 bytes, checksum: 8aa6e24d8b24fa74ffa52a7b23803d30 (MD5) / Made available in DSpace on 2016-07-14T10:37:04Z (GMT). No. of bitstreams: 1 lucianoambrosioferreira.pdf: 3321721 bytes, checksum: 8aa6e24d8b24fa74ffa52a7b23803d30 (MD5) Previous issue date: 2011-03-25 / A desordem temporomandibular de sintomatologia crônica é acompanhada por uma diversidade de manifestações clínicas e emocionais que interagem de maneira desfavorável na percepção dolorosa dos pacientes. Considerando tal interação, o presente ensaio clínico propôs verificar a eficácia da terapia adjuvante de laser-acupuntura no controle sintomatológico destes pacientes através de uma avaliação duplo-cega controlada por placebo. O estudo foi conduzido em uma amostra de 40 indivíduos do gênero feminino, situados entre as idades de 20 e 40 anos, com diagnóstico de dor miofascial e artralgia crônicas, determinadas pelos Critérios de Diagnóstico para Pesquisas das Desordens Temporomandibulares (RDC/DTM). Os indivíduos foram aleatoriamente divididos em dois grupos: o experimental, que recebeu a terapia de laser-acupuntura adjuvante à intervenção oclusal por placa neuromiorrelaxante (PNMR); enquanto o grupo controle recebeu laser placebo associado à PNMR. Ambas as abordagens foram instituídas por um período de três meses, conduzidas por um mesmo terapeuta, cirurgião-dentista e acupunturista. A terapia de laser-acupuntura aconteceu uma vez por semana, por doze sessões e seguiu os seguintes parâmetros: radiação infravermelha com potência de 50mW, direcionada continuamente por 90 segundos aos pontos de acupuntura: ST6, SI19, GB20, GB43, LI4, LR3, TE3 e EX-HN3, definindo uma energia de 4,5J, uma densidade por ponto de 1250W/cm2 e uma densidade total de 112,5J/cm2. O desfecho principal incluiu a avaliação da evolução da sintomatologia física por meio da verificação mensal da intensidade da dor espontânea e da palpação muscular e articular, indicadas em uma escala visual analógica (EVA). Avaliou-se também a intensidade de sintomas de depressão e somatização por meio do RDC/DTM eixo II, aplicado antes e após a instituição terapêutica. Todas as avaliações foram conduzidas por um avaliador cego. Os resultados revelaram que a partir do primeiro mês das intervenções o grupo experimental exibiu valores de intensidade de dor expressivamente menores (p≤0,05) que o grupo controle, para todas as estruturas examinadas. Ao final das intervenções observou-se a remissão da sintomatologia dolorosa (EVA= 0) no grupo experimental e uma redução dos sintomas no grupo controle (EVA entre 2 e 4). Em relação aos aspectos psicossociais, os níveis de sintomas de somatização e depressão foram modificados com as intervenções 7 adotadas nos dois grupos, no entanto, o grupo experimental apresentou uma significativa diminuição frente ao grupo controle (p ≤ 0,05). A laser-acupuntura adjuvante à terapia oclusal reversível foi eficaz na remissão da sintomatologia física de desordem temporomandibular, além de atuar reduzindo os sintomas físicos inespecíficos e de depressão associados ao estresse e à dor crônica. / The temporomandibular chronic symptoms are accompanied by various clinical and emotional expressions that interact unfavorably on patients’ pain perception. Considering the statement, this clinical trial proposed to verify laser-acupuncture therapy efficacy to the patients’ symptoms through a double-blind evaluation controlled by placebo. The study was conducted on a sample of 40 female subjects, located between the ages of 20 and 40 years, with chronic myofascial pain and arthralgia diagnose, as determined by Research to Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Subjects were randomly divided into two groups: the experimental group that received the laser acupuncture therapy adjunct to reversible occlusal splint therapy (ROST), while the control group received placebo laser associated with ROST. Both approaches have been imposed for three months, driven by the same therapist, dentist and acupuncturist. Laser acupuncture therapy was applied once a week, for twelve sessions, defined by the parameters: infrared laser radiation, 50mW power output, directed punctuality for 90 seconds to acupuncture points: ST6, SI19, GB20, GB43, LI4, LR3, NT3 and EX-HN3, defining 4.5J energy, 1250W/cm2 density point and 112.5 J/cm2 total density. The primary outcome measure included an assessment of the physical symptoms evolution through the monthly check of the intensity of spontaneous and palpation pain, indicated on a visual analogue scale (VAS). The symptoms intensity of depression and somatization was evaluated by the RDC / TMD axis II, administered before and after therapy institution. All evaluations were conducted by a blind assessor. The result shows values of pain intensity significantly lower in experimental group (p ≤ 0.05) since the first month intervention for all structures examined. At the end of the interventions was observed remission of painful symptoms (VAS = 0) in the experimental group and a partial reduction of symptoms in the control group (VAS between 2 and 4). Regarding psychosocial factors, levels of somatization and depression symptoms were modified with the interventions taken in both groups, however, the experimental group showed a significant decrease (p ≤ 0,05) compared to the control group. The laser acupuncture as an adjunct therapy to reversible occlusal splint was effective in remission of temporomandibular disorder physics symptoms, also reducing nonspecific physical 9 symptoms and depression associated with stress and chronic pain.
322

Estudo comparativo dos efeitos do laser de baixa intensidade e do ultrassom terapêutico no reparo tecidual de feridas cirúrgicas cutâneas em ratos Wistar: avaliação histopatológica e produção in situ de mediadores inflamatórios / Comparative study of low intensity laser effects and therapeutic ultrasound in tissue repair of cutaneous surgical wounds in Wistar rats: histopathology and in situ production of inflammatory mediators

Bertges, Thaís Abranches Bueno Sabino 14 September 2015 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-12T13:26:08Z No. of bitstreams: 1 thaisabranchesbuenosabinobertges.pdf: 1644405 bytes, checksum: 3b8373f3de0b6d396b5af331c1897b4a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T17:14:55Z (GMT) No. of bitstreams: 1 thaisabranchesbuenosabinobertges.pdf: 1644405 bytes, checksum: 3b8373f3de0b6d396b5af331c1897b4a (MD5) / Made available in DSpace on 2016-01-25T17:14:55Z (GMT). No. of bitstreams: 1 thaisabranchesbuenosabinobertges.pdf: 1644405 bytes, checksum: 3b8373f3de0b6d396b5af331c1897b4a (MD5) Previous issue date: 2015-09-14 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / A cicatrização é um evento complexo que tem por objetivo restaurar a integridade anatômica, histológica e funcional de um tecido que sofreu lesão por diferentes etiologias. O potencial de modulação do sistema imunológico e das reações inflamatórias locais, por técnicas não invasivas, é alvo de diversos trabalhos e apesar de tal efeito modulador já ser comprovado clinicamente e corroborado por estudos histomorfológicos, os mecanismos celular e molecular de ação local e sistêmica das principais terapias adjuvantes disponíveis, a laserterapia de baixa intensidade e o ultrassom terapêutico, ainda não estão totalmente esclarecidas. O objetivo do presente estudo foi comparar os efeitos da terapia a laser de baixa intensidade e do ultrassom terapêutico, isolados e associados no processo de reparo tecidual, de feridas cutâneas cirúrgicas em ratos Wistar, com pesquisa da produção in situ de TGF-β1, TGF-β2 e IL-17 por imuno-histoquímica, além de avaliar, por histomorfometria, a deposição de matriz colagenosa na área em cicatrização por estudo retrospectivo em material emblocado em parafina (n = 24), cujas amostras foram divididas em: um grupo controle (GI), um submetido apenas à laserterapia (GII), um submetido apenas ao ultrassom (GIII) e um submetido às duas terapias associadas (GIV). Os dados foram expressos em média e desvio padrão, sendo considerado p < 0,05 para indicar resultados estatisticamente significantes. A expressão de TGF-β1 foi significativa quando as amostras de GIV foram comparadas com GII e GIII. Em relação a IL-17, as amostras de GI e de GII apresentaram maior porcentagem de células coradas, e a diferença foi significativa entre GII e GIII, e entre GII e GIV. / Wound healing is a complex event that aims to restore anatomical, histological and functional integrity of a tissue injury suffered by different etiologies. The potential modulation of the immune system and local inflammatory reactions by noninvasive techniques is the subject of several studies and although such modulating effect already being clinically proven and confirmed by histopathologic studies, the cellular and molecular mechanisms of local and systemic actions of main adjuvant therapies available, the low level laser therapy and ultrasonic energy, are still unclear. The aim of this study was to compare the effects of laser therapy of low intensity and the therapeutic ultrasound, isolated and associates in the tissue repair process in surgical wounds in Wistar rats, with research in situ production of TGF-β1, TGF-β2 and IL-17 by immunohistochemistry, and to evaluate by histomorphometry, the deposition of collagenous matrix in the area in healing by retrospective study in emblocado material paraffin (n = 24), the samples were divided into: a control group (GI) one subject only to laser therapy (GII), a submitted only to the ultrasound (GIII) and submitted to the two associated therapies (GIV). Data were expressed as mean and standard deviation, being considered p < 0.05 to indicate a statistically significant results. The TGF-β1 expression was significant when samples of GIV were compared with GII and GIII. With regard to IL-17, samples of GI and GII had a higher percentage of stained cells, and the difference was significant between GII and GIII, and between GII and GIV.
323

Etude d’un module accélérateur supraconducteur et de ses systèmes de régulation pour le projet MYRRHA / Study of an accelerating superconducting module and its feedback loop systems for the MYRRHA project

Bouly, Frédéric 03 November 2011 (has links)
Afin d'étudier la faisabilité de la technologie ADS (« Accelerator Driven System ») pour la transmutation des déchets hautement radiotoxiques le projet MYRRHA (« Multi-purpose hYbrid Research Reactor for High-tech Applications ») a pour objectif la construction d'un démonstrateur de réacteur hybride (50 à 100 MWth). Pour cela le réacteur sous-critique nécessite un accélérateur de forte puissance délivrant un faisceau continu de protons (600 MeV, 4mA), avec une exigence de fiabilité très élevée. La solution de référence retenue pour cette machine est un accélérateur linéaire supraconducteur. Ce mémoire de thèse décrit le travail de recherche - entrepris depuis octobre 2008 à l'IPN d'Orsay - portant sur la conception et la mise au point d'un module supraconducteur et des systèmes de régulation associés à sa cavité accélératrice, pour la partie haute énergie de l’accélérateur. Dans un premier temps, le design et l’optimisation de cavités accélératrices 5-cellules (β=0,65), fonctionnant à la fréquence de 704,4 MHz, sont présentés. Ensuite, la partie expérimentale se concentre sur l’étude de fiabilité du « cryomodule » prototype accueillant une cavité elliptique 5-cellules (β=0,47). Au cours de cette étude on s’est notamment attaché à mesurer et à caractériser le comportement dynamique du système d’accord. Les problématiques de maintient du « plat de champ » dans les cavités multi-cellules « bas béta » ont aussi été mises en évidence. Enfin, une analyse sur la tolérance aux pannes de l’accélérateur linéaire a été menée. Dans ce but, une modélisation de la cavité, de sa boucle de régulation RF (radiofréquence) et de la boucle de contrôle de son système d'accord, a été développée afin d'étudier les comportements transitoires de cet ensemble. Cette étude a permis de chiffrer les besoins en puissance RF et les performances requises du système d’accord et de démontrer la faisabilité d’un réglage rapides des cavités supraconductrices afin de minimiser le nombre d’arrêts faisceau dans le linac de MYRRHA. / The MYRRHA ( Multi-purpose hYbrid Research Reactor for High-tech Applications ) project aims at constructing an accelerator driven system (ADS) demonstrator (50 à 100 MWth) to explore the feasibility of nuclear waste transmutation. Such a subcritical reactor requires an extremely reliable accelerator which delivers a CW high power protons beam (600 MeV, 4 mA). The reference solution for this machine is a superconducting linear accelerator. This thesis presents the work - undertaken at IPN Orsay in October 2008 - on the study of a prototypical superconducting module and the feedback control systems of its cavity for the high energy part of the MYRRHA linac. First, the optimization and the design of 5-cell elliptical cavities (β=0,65), operating at 704.4 MHz, are presented. Then, the experimental work focuses on a reliability oriented study of the “cryomodule” which hold a prototypical 5-cell cavity (β=0,47). In this study, the dynamic behavior of the fast tuning system of the cavity was measured and qualified. The “field flatness” issue in “low beta” multi-cell cavity was also brought to light. Finally, a fault-tolerance analysis of the linac was carried out. Toward this goal, a model of the cavity, its RF feedback loop system and its tuning system feedback loop was developed. This study enabled to determine the RF power needs, the tuning system requirements and as well as to demonstrate the feasibility of fast fault-recovery scenarios to minimize the number of beam interruptions in the MYRRHA linac.
324

Dielektrická spektroskopie karboxymetylcelulózy v časové oblasti / Time-domain Dielectric Spectroscopy of Carboxymethylcellulose

Palai-Dany, Tomáš January 2009 (has links)
The dissertation deals with the time-domain dielectric relaxation spectroscopy of carboxymethylcellulose. The main attention was paid to the experimental part of research, mainly to the design and subsequent development of an experimental setup for the measurement of discharge currents and for their processing and analysis. The subject of the measurement is carboxymethylcellulose (CMC), which is a simple polysaccharide used in wide range of applications, among else also in biomedical engineering. The study of CMC properties has required the development of a new experimental set-up of original design, which includes the equilibration (short-circuiting) of a sample before the measurement, charging and discharging at defined time intervals, switching between these two modes, recording of measurement, adjustments and processing of measured signals up to Fourier transformation into the frequency domain and, finally, calculation of complex permittivity of the sample. The frequency dependence of complex permittivity or its imaginary part, obtained by Fourier transformation of discharge current in time domain, is then referred to as the dielectric spectrum. In view of the fact that current measurements were done at very low levels of measured signal (below 10-12 A) the whole measurement was no easy matter. The framework of the work also necessitated studies and subsequent resolution of problems associated with shielding, grounding, presence of noise and sensitivity to various ambient influences. The research work focused on a reliable and trustworthy measurement of very low discharge currents and, subsequently, mathematical processing of noise present in them, i.e., operations with the original, experimentally established signal in time domain, leading in principle to a digital filtration of measured dielectric data. A further pursued objective is the explanation of dielectric parameters of tested carboxymethylcellulose sample in the widest possible frequency spectrum. The integral part of the research was the selection and application of the method for the transformation of the adjusted signal to the frequency domain. The experimental works, including data processing, were carried out in the Department of Physics, Brno FEEC BUT. Measurements were done with Keithley 617 Electrometer, HP4284A Frequency Analyzer and Janis CCS-400-204 cryogenic system. The results were completed with results obtained at the V Department of Experimental Physics, Centre for Electronic Correlations and Magnetism, University of Augsburg, Germany.
325

Nízkoúrovňová měření / Low level measurement

Roubal, Zdeněk January 2016 (has links)
The doctoral thesis presents methods for low-level measurements, which are exemplified by the general measurement of air ion concentration. Within the first section, the author progressively identifies certain critical effects influencing the concentration of air ions, and these effects are to be considered in evaluating the uncertainty of the measured concentrations. Thus, the thesis aims to provide a systematic description of the procedures and requirements related to low-level measurements; the proposed description then involves a discussion of the process reliability requirements, namely the factors of repeatability, elimination of errors, and definition and describability of measurement uncertainties. Such methodology facilitates, among other activities, the long-term monitoring of air ion concentration in extreme environments, including caves or spaces characterized by high temperatures and humidity. The use of common methods for determining the air ion mobility spectrum is accompanied by a number of disturbing effects, such as spurious fluctuation in the concentration of air ions in time. The experimental section of the thesis describes the testing of different configurations of the measuring device (a collecting electrode and a polarization capacitor); at this stage, we seek the most advantageous distribution of the electrostatic field in the sensor – a Gerdien tube. The systematic suppression of the influence of spurious fluctuations in air ion concentration during the measurement of saturation characteristics is carried out with the least-squares numerical method (as a supporting element), a hybrid technique to describe and evaluate the experimental model. In the second part of the thesis, the methodology of low-level measurement is complemented with procedures for the measurement of freezing potential. This latter domain, as an overall experimental approach applicable during phase changes of the sample, has hitherto not been sufficiently characterized from the metrological perspective, in an up-to-date manner; several subregions of the said domain remain somewhat obscured and deserve significantly more attention. In the given context, this thesis systematically considers a problem where comparable measurement results produced by multiple authors are not available. The measuring methodology proposed herein was utilized in applied research to facilitate the fabrication of an apparatus for the experimental measurement of freezing potential in pre-defined samples; the obtained results then lead us to conclusions with respect to the evaluation of effects that cause differences in the measured data, and the results can be further compared with those obtained by other researchers investigating the given segment of the problem.
326

Získávání znalostí z multimediálních databází / Knowledge Discovery in Multimedia Databases

Málik, Peter January 2011 (has links)
This master"s thesis deals with the knowledge discovery in multimedia databases. It contains general principles of knowledge discovery in databases, especially methods of cluster analysis used for data mining in large and multidimensional databases are described here. The next chapter contains introduction to multimedia databases, focusing on the extraction of low level features from images and video data. The practical part is then an implementation of the methods BIRCH, DBSCAN and k-means for cluster analysis. Final part is dedicated to experiments above TRECVid 2008 dataset and description of achievements.
327

Získávání znalostí z obrazových databází / Knowledge Discovery in Image Databases

Jaroš, Ondřej January 2010 (has links)
This thesis is focused on knowledge discovery from databases, especially on methods of classification and prediction. These methods are described in detail.  Furthermore, this work deals with multimedia databases and the way these databases store data. In particular, the method for processing low-level image and video data is described.  The practical part of the thesis focuses on the implementation of this GMM method used for extracting low-level features of video data and images. In other parts, input data and tools, which the implemented method was compared with, are described.  The last section focuses on experiments comparing extraction efficiency features of high-level attributes of low-level data and the methods implemented in selected classification tools LibSVM.
328

Echecs virologiques au sein de cohortes hospitalières de patients adultes infectés par le VIH : apport de l'ultra-deep sequencing et étude des charges virales de faible niveau persistantes / Virological failure in cohorts of HIV-infected patients : contribution of ultra-deep sequencing and impact of persistent low-level viremia

Vandenhende, Marie-Anne 24 November 2015 (has links)
L’objectif d’un traitement antirétroviral (ARV) est d’obtenir une charge virale VIH plasmatiqueindétectable afin de réduire la morbi-mortalité associée au VIH.La résistance du virus aux ARV est un facteur de risque d’échec virologique (EV). Les testsgénotypiques de résistance par séquençage classique (méthode de Sanger) ne permettent pas dedétecter les virus porteurs de mutations de résistance (MR) présents à taux minoritairereprésentant moins de 20% de la population virale plasmatique. Dans notre étude (cohorteANRS CO3), l’utilisation de l’ultra-deep sequencing (UDS) a permis de détecter 1.4 fois plusde MR avant traitement et 1.3 fois plus à l’EV en comparaison à la technique de séquençageclassique, confirmant la haute sensibilité de l’UDS pour la détection des MR. Les MRminoritaires détectées uniquement par UDS augmentaient la résistance génotypique du virus autraitement ARV chez 4% des patients à l’initiation du traitement et 21% des patients à l’EV.Les conséquences des épisodes de charges virales de faible niveau persistantes (CVF) entre 50et 200 copies/ml (CVF50-200) ne sont pas clairement établies du fait de l’insuffisance dedonnées dans la littérature. Dans nos études de cohortes (cohortes ANRS CO3 et ART-CC), 4-9% des patients ont présenté au moins un épisode de CVF50-200. La survenue d’une CVF50-200 était associée à un risque plus de 2 fois plus élevé d’EV>200 copies/ml, quels que soient ladurée de la CVF, l’historique de traitement ou le traitement ARV lors de la CVF50-200(régimes comportant des INNTI ou des IP/r). La survenue d’une CVF n’était pas associée à lasurvenue d’un évènement classant SIDA ni au décès, avec toutefois un suivi médian de 3 ans. / The goal of antiretroviral therapy (ART) is to reach undetectable plasma HIV viral load in orderto reduce HIV-related morbidity and mortality.The presence of ART-resistant virus can compromise the efficiency of these treatments,resulting in virological failure (VF). Standard genotyping by Sanger sequencing (SS) usedcurrently in clinical practice cannot detect low-frequency viral variants harbouring drugresistance associated mutations (DRM) representing less than 20% of the viral population. Inour study, the use of ultra-deep sequencing (UDS) allowed us to detect 1.4-fold more DRMsbefore ART and 1.3-fold more DRMs at VF compared to SS, confirming the high sensitivity ofUDS for the detection of DRMs. The low-frequency DMRs detected only by UDS modified thegenotypic resistance of the virus to the prescribed treatment for 4% of the patients before ARTinitiation and for 21% of the patients at VF.The impact of persistent low-level viremia (LLV) between 50 and 200 copies/ml (LLV50-200)remains uncertain due to the lack of controlled comparison data. In our cohort studies (ANRSCO3 and ART-CC cohorts), 4-9% of HIV-infected patients experienced at least one episode ofLLV50-200. LLV50-200 was strongly associated with a twice higher risk of VF>200copies/ml,independently of the duration of LLV, the history of treatment or the type of ART regimen atLLV (NNRTI or PI-based regimens). LLV was not associated with AIDS event or death witha median follow-up of only 3 years.
329

Wavebender GAN : Deep architecture for high-quality and controllable speech synthesis through interpretable features and exchangeable neural synthesizers / Wavebender GAN : Djup arkitektur för kontrollerbar talsyntes genom tolkningsbara attribut och utbytbara neurala syntessystem

Döhler Beck, Gustavo Teodoro January 2021 (has links)
Modeling humans’ speech is a challenging task that originally required a coalition between phoneticians and speech engineers. Yet, the latter, disengaged from phoneticians, have strived for evermore natural speech synthesis in the absence of an awareness of speech modelling due to data- driven and ever-growing deep learning models. By virtue of decades of detachment between phoneticians and speech engineers, this thesis presents a deep learning architecture, alleged Wavebender GAN, that predicts mel- spectrograms that are processed by a vocoder, HiFi-GAN, to synthesize speech. Wavebender GAN pushes for progress in both speech science and technology, allowing phoneticians to manipulate stimuli and test phonological models supported by high-quality synthesized speeches generated through interpretable low-level signal properties. This work sets a new step of cooperation for phoneticians and speech engineers. / Att modellera mänskligt tal är en utmanande uppgift som ursprungligen krävde en samverkan mellan fonetiker och taltekniker. De senare har dock, utan att vara kopplade till fonetikerna, strävat efter en allt mer naturlig talsyntes i avsaknad av en djup medvetenhet om talmodellering på grund av datadrivna och ständigt växande modeller fördjupinlärning. Med anledning av decennier av distansering mellan fonetiker och taltekniker presenteras i denna avhandling en arkitektur för djupinlärning, som påstås vara Wavebender GAN, som förutsäger mel-spektrogram som tas emot av en vocoder, HiFi-GAN, för att syntetisera tal. Wavebender GAN driver på för framsteg inom både tal vetenskap och teknik, vilket gör det möjligt för fonetiker att manipulera stimulus och testa fonologiska modeller som stöds av högkvalitativa syntetiserade tal som genereras genom tolkningsbara signalegenskaper på lågnivå. Detta arbete inleder en ny era av samarbete för fonetiker och taltekniker.
330

High- and low-level factors in visual attention

Kaspar, Kai 17 July 2013 (has links)
The visual sense has outstanding importance for humans’ interaction with the environment and visual attention is the key mechanism that bundles our limited cognitive resources in order to enhance the perceptual processing of the most relevant environmental features at a certain point in time. Eye-Tracking technology enables us to accurately observe peoples’ eye movement behavior i.e. overt attention. In the last decade, overt attention on real-world scenes gained increasing popularity in vision research. The higher ecological validity of such scenes in combination with a free-viewing task allows us to investigate human viewing behavior under natural conditions. In this context, the majority of previous studies focused on the impact of basal image properties, such as color and luminance differences, to quantify the extent to which our fixation behavior is guided by these so-called low-level image properties. However, in most experimental studies complex images are observed only one time, whereas we are continually confronted with repeated visual impressions in everyday life. Therefore, I introduce a repeated-presentation-design that allows scrutinizing the impact of low-level image properties and the power of scene types over time. Besides these low-level factors, I also address inter-individual differences in motivation as well as emotional components as so-called high-level factors in overt attention. Previous research on visual attention has widely neglected these factors, especially in the context of real-world images. On the basis of novel study designs and by means of various analysis techniques, I show how several low- and high-level factors influence overt attention on complex scenes, how they interact, and how eye movement parameters are interrelated. In addition to that, I provide a comprehensive review of the previous literature on emotions’ and personality traits’ impacts on visual attention. On the basis of the inconsistent understanding of core concepts in the literature, I describe how behaviorally oriented studies investigate these high-level factors in visual attention, how the interplay between emotion and attention is conceptualized from a neuroscientific perspective, and I derive several conceptual and practical recommendations for future research. Finally, I outline some new ideas and venues for future research in the general discussion of the present work, for example how eye-tracking might overcome some fundamental problems of classical testing in psychological diagnostics, or how the view of embodied cognition can help us to get a better understanding of high- and low-level factors in visual attention.

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