Thesis (MEng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Rapid prototyping (RP) technologies have expanded vastly over recent years. With the advent of new materials along with new processes, each technology has been contributing to the diversities in different fields of application for the growing technologies. In the course of improvement, it is however critical to understand exactly what the capability of each individual technology is in order to compare future improvements, or even to compare current processes and technologies. The objective of this research has been to develop capability profiles of prominent RP technologies: 3D-Printing (3DP), Selective Laser Sintering (SLS), and Laminated Object Manufacturing (LOM) - in which different characteristics of each technology are measured and quantified. A capability profile may be regarded as a set of building blocks that give a representation of the RP technology's ability and is defined by quantifying the following characteristics: Accuracy (both dimensional- and geometrical accuracy) Surface finish measures Strength and elongation Build time, and Cost The significance behind developing capability profiles lies in the need to more accurately describe and compare each of the different processes - especially Z Corporation's 3DP, since although this process is regarded as very capable in many areas, little has been published to substantiate this opinion. When users of these technologies are pushing the limits of their machines, it becomes critical to know exactly what these boundaries are in order to know with some measure of certainty that they will be able to fulfil a certain customer demand or expectation. For South Africa in particular, the industry's growing interest in rapid prototyping is triggering inevitable questions as to whether a certain RP technology can produce the desired solutions to their problems. The South African industry's growing awareness about rapid prototyping is opening new doors for better solutions to new and existing problems - but ultimately, before investing money, customers want to know if RP is going to meet the standards needed to solve their solutions. On a more general level, this study can also be seen to bear significance in contributing to research in what has become known as rapid manufacturing (RM). This term is defined as the manufacture of end-use products using additive manufacturing techniques. RM must guarantee long-term consistent component use for the entire product life cycle or for a defined minimal period for wearing parts [1]. However, before it is possible to guarantee long-term consistency of components, one must first ensure consistency of the process. Once a process is consistent, the next question becomes: What is it capable of doing consistently? This study aims to answer this question for the three processes (3DP, SLS and LOM) mentioned earlier. In doing so, this study and its development of capability profiles, seeks to contribute and be of value in both academic circles as well as for industry partners and system manufacturers. / AFRIKAANSE OPSOMMING: Snelle Prototipering (SP) tegnologieë het die afgelope jare ongelooflike groei ondervind. Met die ontwikkeling van nuwe materiale tesame met nuwe prosesse, het elke tegnologie bygedra tot 'n diversiteit in moontlike toepassings vir 'n verskeidenheid van velde. Met 'n mikpunt van aaneenlopende verbetering, is dit egter krities om te verstaan presies wat elke individuele tegnologie se vermoëns is. Dit maak dit dan moontlik om toekomstige verbeteringe te vergelyk, of om selfs huidige prosesse met mekaar te vergelyk. Die doel van hierdie navorsing was om vermoënsprofiele van prominente SP tegnologieë te ontwikkel: 3D-Printing (3DP), Selective Laser Sintering (SLS) en Laminated Object Manufacturing (LOM) - waarin verskillende karaktereienskappe van elke tegnologie gemeet en gekwantifiseer word. 'n Vermoënsprofiel mag beskou word as 'n stel boustene wat 'n weerspieëling gee van die SP tegnologie se vermoë en word gedefinieer deur die kwantifisering van die volgende karaktereienskappe: Akkuraatheid (beide dimensionele- en geometriese akkuraatheid) Oppervlakgehalte metings Treksterktes en verlengings Bou- of vervaardigingstye, en Kostes Die rede waarom dit belangrik is om vermoënsprofiele te ontwikkel berus by die behoefte om die verskillende prosesse met meer akkuraatheid te beskryf en te vergelyk - veral Z Corporation se 3DP. Alhoewel hierdie proses algemeen beskou word as baie bevoeg in vele areas, is min informasie al gepubliseer om hierdie opinie te ondersteun. Wanneer gebruikers van hierdie tegnologieë hul masjiene tot die limiete druk, begin dit krities raak om presies te weet wat daardie grense is, sodat hulle met 'n sekere mate van sekerheid sal kan sê of hulle sal kan voldoen aan kliënte se behoeftes of verwagtinge. Die Suid-Afrikaanse industrie se belangstelling in SP tegnologieë begin al hoe meer groei, en daarmee saam, begin vrae ontstaan tot watter mate snelle prototipering wel werkbare oplossings kan produseer vir hul probleme. Hierdie groeiende bewustheid van die Suid-Afrikaanse industrie begin dus ook nou nuwe paaie openbaar vir beide nuwe en ou probleme - maar uiteindelik, voordat kliënte egter bereid sal wees om geld te belê, sal hulle wil weet of snelle prototipering die standaarde gaan behaal wat nodig sal wees om juis hierdie oplossings te verwesenlik. Op 'n meer breë vlak, beoog hierdie studie om ook 'n bydrae te maak in die groeiende navorsingsveld van snelle vervaardiging (SV). Hierdie is 'n term wat gedefinieer word as die vervaardiging van endgebruiker produkte, met die benutting van byvoegings-vervaardigings tegnieke. SV moet versekering bied vir komponente se werkverrigting op die lange duur vir die hele produk se lewenssiklus, of ten minste vir 'n gedefinieerde minimale tydperk in die geval van slytasie-parte [1]. Maar voordat dit moontlik sal wees om hierdie versekering te bied, moet mens eers die versekering kan bied van 'n proses se werkverrigting. Wanneer die prosesse betroubaar en deurlopende resultate lewer, word die volgende logiese vraag gestel: Wat presies, is hierdie proses in staat om betroubaar te lewer? Hierdie studie beoog om juis hierdie vraag te beantwoord vir die drie prosesse (3DP, SLS en LOM) wat vroeër genoem is. Dienooreenkomstig, met die ontwikkeling van vermoënsprofiele van hierdie prosesse, behoort hierdie studie van waarde te wees vir beide akademici, sowel as industrie-lede en vervaardigers van SP tegnologieë.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Acute synovitis and capsulitis are common articular problems and can contribute to the development of a degenerative process due to the release of enzymes and inflammatory mediators. The indicated treatment for synovitis and capsulitis is based on anti-inflammatory drugs. An experimental synovitis model was used in ponies to evaluate the effect of parecoxib, a selective ciclo-oxygenase 2 anti-inflammatory drug. Cardiac (FC) and respiratory frequency (FR) and rectal temperature (T) were determined. The ponies also had their stride length (CP), carpal joint angle at rest (AR), angle of maximum flexion (AFM), joint circumference (CA), carpal effusion degree (GE) and lameness degree (GC) evaluated. The analysis of the synovial fluid included cytology, protein, mucin precipitation quality and viscosity. After synovitis induction with Freund s complete adjuvant, three ponies were treated with 0,55mg/kg/day IV parecoxib, and three received sterile 0,9% saline solution (IV) for five days. Clinical and synovial fluid parameters were evaluated before synovitis induction, immediately before treatment and 12, 24, 48, 96 and 120 hours after the first treatment. Induced synovitis findings were similar to natural occurring ones. Repeated artrocentesis increased protein in the synovial fluid, but did not modify the other evaluated parameters of the healthy joints. Synovial fluid parameters were not affected by parecoxib treatment. Protein amount and total leukocyte count increased and remained high up to 120 hours of the beginning of treatment, and the viscosity and mucin precipitation quality decreased in synovitis induced joints. The intra-articular injection of Freund s complete adjuvant induced a moderate to serious synovitis. Significant increases in T, FC, GC and GE and reduction of AFM and CP occurred in the synovitis control group. Treated ponies showed GC reduction, maintenance of the AFM, CP, T and FC and attenuation of GE. Although the used dosage of parecoxib had no effect on evaluated synovial fluid parameters, analgesic, antipyretic and anti-inflammatory effects were observed. / Sinovite e capsulite agudas são problemas comuns em algumas articulações e podem resultar em um processo degenerativo pela liberação de enzimas e mediadores inflamatórios. O tratamento recomendado nestes casos são os antiinflamatórios não esteroidais (AINEs). Com o objetivo de avaliar o efeito do parecoxib, um AINE seletivo para cicloxigenase 2 injetável, foi usado um modelo experimental de sinovite em pôneis. No exame clínico geral foi determinada a freqüência cardíaca (FC) e respiratória (FR) e a temperatura retal (T). No exame clínico específico foram avaliados o comprimento do passo (CP), ângulo do membro em repouso (AR), ângulo de flexão máxima (AFM), circunferência articular (CA), grau de efusão carpal (GE) e grau de claudicação (GC). A análise do líquido sinovial foi realizada através da citologia, concentração de proteína, qualidade do precipitado da mucina e viscosidade. Cinco dias após indução da sinovite com adjuvante completo de Freund, três pôneis foram tratados com 0,55mg/kg/dia de parecoxib (IV) e três receberam solução fisiológica estéril 0,9% (IV) por cinco dias. A avaliação dos parâmetros clínicos gerais e específicos, e das características celulares e bioquímicas do fluido sinovial foi realizada antes da indução de sinovite, imediatamente antes do tratamento e 12, 24, 48, 72, 96 e 120 horas após início do tratamento. A sinovite induzida neste experimento foi semelhante a uma sinovite naturalmente ocorrida. A artrocentese repetida, apesar de contribuir para o aumento da proteína no fluido sinovial, não modificou significativamente os outros parâmetros avaliados das articulações sadias. O tratamento com parecoxib não influenciou significativamente os parâmetros do líquido sinvovial, pois a quantidade de proteína e de leucócitos totais aumentou, e a qualidade da viscosidade e da precipitação da mucina diminuiu com a indução da sinovite, permanecendo sem alteração até 120 horas após o início do tratamento. A injeção intra-articular com adjuvante completo de Freund, induziu uma sinovite de intensidade moderada a grave. Ocorreram aumentos significativos na T, FC, GC e GE e diminuição do AFM e CP no grupo controle. Já os pôneis tratados com parecoxib apresentaram diminuição do GC, manutenção do AFM, CP, T e FC e atenuação do GE articular. Portanto, embora o parecoxib, na dose utilizada, não tenha apresentado efeito sobre os parâmetros do líquido sinovial das articulações com sinovite, sua ação antipirética, antiinflamatória e analgésica foi documentada.

Provisional Question for the thesis to address: Indicated and selective prevention of common mental health problems in later life: Is there a theoretical rationale for an Acceptance and Commitment Therapy approach? Background The burden of late life depression and anxiety is significant. Even subthreshold symptoms result in great individual, community, economic and societal cost. However, common mental health problems in later life are under‐recognised and under‐treated despite evidence in support of pharmacological and psychological intervention. Previous research regarding psychological therapy for late life mental health problems has been dominated by cognitive behavioural therapy. However, the effectiveness of this approach has been questioned, leading researchers to explore alternative approaches. Acceptance and Commitment Therapy has received increasing attention from researchers keen to explore an alternative and some have argued that this approach is particularly suited to older people. In the context of demographic change and a significant increase in the proportion of community dwelling elderly there is a need to provide evidence to support the use of alternative management strategies for late life mental health problems, for example, focusing on prevention. Methods A systematic review will evaluate the current evidence for the use of ‘indicated’ and ‘selective’ prevention interventions for older people at risk of developing a major depressive or anxiety disorder due to the experience of subsyndromal symptoms or the presence of significant physical, socioeconomic, and psychosocial risk factors. This paper will be followed by an empirical article in which the relationship between psychological processes and ageing will be explored. Specifically, this study will explore psychological flexibility, the use of Selection, Optimisation and Compensation strategies, and the presence of psychopathology in a non clinical sample of community dwelling older people. Results Findings of the systematic review provide preliminary evidence for indicated and selective prevention of late life depression, however there is no clear evidence of benefits of these interventions in late life anxiety. The relationships between variables in the empirical study were explored using descriptive statistics, correlation analysis, and conditional process modelling. Although the study did not find age to be a specific predictor of variance in psychological variables explored, the study did provide empirical support for the potential to use Acceptance and Commitment Therapy with older people. Discussion The systematic review article provided preliminary evidence for the efficacy of selective and indicated prevention interventions for late life depression. However, further research is required to consolidate these findings. The empirical paper found significant relationships between the perception of positive health, reduced psychopathology and theoretical variables including cognitive fusion, engagement in valued living, and the use of Selection, Optimisation, and Compensation strategies. Cognitive fusion was found to mediate these relationships and as such, findings provide support for the use of an Acceptance and Commitment Therapy approach with older people. The theoretical and clinical implications of these findings are discussed in detail.

Tabagistas atendem seletivamente a estímulos ambientais relacionados ao cigarro, um processo cognitivo implícito denominado viés na atenção (VA). Contudo, não está claro se o VA persiste em ex-fumantes. Por isso, avaliou-se a influência do tempo de abstinência no VA em 62 ex-fumantes (de 50±11 anos) através de uma tarefa de atenção visual em computador. Independente do tempo de abstinência, os participantes evitaram as pistas associadas ao tabaco. Esta esquiva foi mais pronunciada em tempos de exposição maiores. Os ex-fumantes também atribuíram pouca valência emocional às imagens associadas ao cigarro e reportaram índices baixos de fissura antes e após a tarefa. O VA negativo e a menor valência emocional destas pistas podem constituir um processo de modulação da atenção típico da abstinência prolongada, no qual estratégias cognitivas são empregadas para manter este estado. Os resultados obtidos contribuem para a compreensão da cognição implícita na adição e sua importância no tratamento e prevenção do tabagismo. / Smokers selectively attend to smoking-related cues, an implicit cognitive process called attentional bias (AB). However, it is unclear whether former smokers present AB. Therefore, we evaluated the influence of abstinence time in VA in 62 exsmokers (50 ± 11 years-old) through a visual probe task. Participants avoided smoking cues despite of abstinence time. This avoidance was more pronounced in longer stimuli exposition. Former smokers also attributed little emotional valence to smoking cues and reported low craving rates both before and after the task. The negative AB and low emotional valence of smoking cues might constitute a process of attentional modulation typical of longer abstinence, in which cognitive strategies are employed to maintain this state. The results contribute to the understanding of implicit cognition in addiction and its importance to smoking treatment and prevention.

Introdução: As mucopolissacaridoses (MPS) são um conjunto de sete doenças genéticas incluídas dentro das Doenças Lisossômicas que por sua vez fazem parte dos Erros Inatos do Metabolismo (EIM). São doenças multissistêmicas que afetam todo o organismo, com variações conforme o tipo de MPS, sendo que algumas delas possuem tratamento específico. Quase todas comprometem, em graus variados, o sistema osteoarticular, e praticamente todos os pacientes apresentam excreção alterada de glicosaminoglicanos (GAGs) na urina. As MPS são doenças raras que podem ser subdiagnosticadas em função do pouco conhecimento dos profissionais de saúde sobre elas, do pouco acesso aos métodos de triagem e diagnóstico e da sua ampla heterogeneidade clínica, podendo ocorrer formas atenuadas nas quais pode ser difícil de levantar a suspeita clínica de MPS. Material e métodos: o presente estudo foi realizado no período de março de 2012 à janeiro de 2014, tendo incluído 55 pacientes atendidos em serviços de Reumatologia e/ou Ortopedia de Porto Alegre, RS, Brasil e que, apresentavam como principal queixa, manifestações articulares sem etiologia definida. Esses pacientes foram inicialmente investigados através da avaliação quantitativa e qualitativa dos GAGs urinários. Resultados e Discussão: entre os 55 casos investigados, em 1 paciente de 15 anos de idade foi observada na análise dos GAGs urinários excreção aumentada e alteração do padrão qualitativo, sendo posteriormente confirmado o diagnóstico de uma forma atenuada de MPS II, a qual não havia sido suspeitada anteriormente. Conclusão: embora a proporção de pacientes identificados com MPS na amostra estudada tenha sido pequena (1/55), este estudo mostra que ocorre subdiagnóstico dessas doenças e que a triagem sistemática pode contribuir para a identificação de pacientes, os quais podem se beneficiar das medidas de tratamento disponíveis. / Introduction: Mucopolysaccharidoses (MPS) are a set of 7genetic diseases including Lysosomal Diseases , which in turn are part of Inborn Errors of Metabolism (IEM). The MPS are multisystemic conditions that affect the entire body, with variations depending on the type, some of which have specific treatment. Almost all affect, in variable degrees, the osteo-articular system, and virtually all patients have abnormal excretion of glycosaminoglycans (GAGs) in urine. The MPS are rare diseases that are being underdiagnosed due to the little knowledge of health professionals about them, the poor access to screening and diagnostic methods and their extensive clinical heterogeneity. Also, attenuated forms may occur in which it may be difficult to raise the clinical suspicion of MPS. Material and Methods: The present study was conducted from March 2012 to January 2014 and included 55 patients from Rheumatology and/or Orthopedics services of Porto Alegre, RS, Brazil and which had, as main complaint, articular manifestations without defined etiology. These patients were screened by quantitative and qualitative assessment of urinary GAGs. Results and Discussion: Among the 55 cases investigated, in 1 patient 15 years of age was observed in the analysis of urinary GAG excretion and increased change in qualitative standard and subsequently confirmed the diagnosis of an attenuated form of MPS II, which had not previously been suspected. Conclusion: Although the proportion of patients with MPS identified in the study sample was small (1/55), this study shows that occurs underdiagnosis of these diseases and that systematic screening can help to identify patients who may benefit from measures treatment available.

Title: Photoluminescence of CdTe crystals Author: Jan Procházka Department: Institute of Physics of Charles University in Prague Supervisor: Doc. RNDr. Pavel Hlídek, CSc. Abstract: Energy levels connected with defects in nominally undoped crystals CdTe, indium- doped crystals and chlorine-doped crystals were studied using low-temperature photoluminescence. The crystals are intended for X- and gamma- ray detectors operated at room temperature. An effect of annealing in cadmium or tellurium vapor on luminescence spectra was investigated. Some changes were interpreted by filling of vacancies not only by atoms coming from gaseous phase but also by impurities from defects like interstitials, precipitates, inclusions, grain boundaries etc. The luminescence bands assigned to defects important for compensation mechanism were examined, namely A-centers (complexes of vacancy in cadmium sublattice and impurity shallow donor) and complexes of two donors bound to a vacancy. It was shown, that temperature dependence of the luminescence bands results from more complicated processes than a simple thermal escape of bound excitons or thermal excitation of electrons (holes) from defects to bands. We observed expressive "selective pair luminescence" bands (SPL) on partially compensated In-doped samples during sub-gap...

Jusqu'à présent, les dispositifs optoélectroniques commerciaux sont épitaxiés selon la direction c, qui souffre de deux limitations intrinsèques. D'une part, les fortes discontinuités de polarisation le long de l'hétéro-interfaces des nitrures qui sont responsables de l'effet Stark de confinement quantique. Ceci mène dans le cas des dispositifs optiques GaN à une séparation de la fonction d'onde électron-trou dans les puits quantiques. D'une autre part, l'incorporation d'indium sur les plans polaires (0001) se trouve être relativement limité par comparaison avec les autres orientations cristallographiques. Ces effets néfastes peuvent être partiellement dépasser en performant la croissance du GaN sur des plans cristallographiques autre que le plan (0001). Ces plans semi polaires conduit éventuellement à l'amélioration des performances du dispositif. En fait, comme la seule solution disponible pour l'instant pour la croissance du GaN semipolaire est l'homoépitaxie, les dispositifs à base de GaN semipolaire de haute qualité a ses inconvénients qui est la petite taille et le prix élevé des substrats. Cela justifie la croissance du GaN semi-polaire sur d'autre type de substrats spécialement le silicium. Dans cette étude, la croissance de couches de GaN semi-polaire (10-11) et (20-21) par MOVPE sur des substrats de silicium structurés sera évaluée. La stratégie générale de fabrication consiste a structuré l'orientation adaptée du substrat silicium de façon à révéler les facettes Si(111). / To-date, commercial III-nitride optoelectronic devices are grown along the c-direction, which suffers two intrinsic limitations. The first is the strong polarization discontinuities across nitride hetero-interfaces that are responsible for the quantum confined Stark effect, leading in the case of GaN-based optical devices to electron-hole wave function separation within the quantum wells, and thus, a decrease in the oscillator strength. The associated longer exciton lifetime together with the occurrence of non-radiative defects, result in reducing the device's efficiency. The second is the indium incorporation on the polar plane, which is relatively limited when compared with its incorporation on other crystallographic orientations. These deleterious effects can be partially overcome by performing the growth of GaN on planes other than (0001), such as semipolar ones leading to the eventual improvement of devices' performances. Growth of device-quality semipolar GaN, however, comes at a price, and the only currently available option is homoepitaxy, which is limited in size and is highly priced. At this point, the growth on foreign substrates becomes appealing, especially on silicon. In this thesis, the MOVPE growth of (10-11) and (20-21) semipolar GaN on patterned silicon substrates has been performed. The general fabrication strategy, which consists of patterning the appropriate silicon wafer orientation in order to reveal the Si (111) facets, will be first described. Subsequently, the selective growth of GaN along the c-direction will be carried out, where the c-oriented crystals will be brought to coalescence until a semipolar layer is achieved.

Cette étude a pour objectif l'étude des processus impliqués dans la production de l'acrylate de 2-éthylhexyle, ester gras dérivé de l'acide acrylique. Cette réaction est accélérée par l'emploi d'un catalyseur solide, une résine acide sulfonée. Les interactions spécifiques des différents composés avec cette résine ont été étudiées à température ambiante. A 90°C, le couplage avec la cinétique de réaction a été analysé et modélisé en réacteur fermé. Un montage pilote spécifique conçu au laboratoire a permis la réalisation de réactions dans un réacteur en lit fixe, dont la structure tripartite permet le suivi des concentrations liquides dans le montage. Une modélisation représentant cette installation a été mise au point, associant l'affinité sélective, la cinétique de réaction et l'hydrodynamique de l'écoulement. Ce modèle a ensuite été utilisé pour l'analyse de modèles de tendances, pour déterminer des conditions de fonctionnement améliorés d'un procédé de taille industrielle / This study aims at analyzing and understanding the processes involved in the production of 2-ethylhexyl acrylate. This fatty ester is a derivative of acrylic acid. This reaction is accelerated by the use of a solid catalyst, a sulfonated resin acid. The specific interactions of compounds with this resin were studied at room temperature. At 90°C, the coupling of kinetics and selective affinity was analyzed and modeled in a closed reactor. A specific pilot installation was designed in laboratory. Esterification reactions were performed. in this fixed bed reactor. The tripartite structure allows the monitoring of liquid levels in all installation. A model representing this system was developed, involving selective affinity, kinetics and hydrodynamic. This model was then used to analyze trends models to determine improved operating conditions for an industrial size process

The Material Point Method (MPM) is a modern finite element method that is classified as a point based method or meshless method, while it takes the advantage of two kinds of spatial discretisation that are based on an arbitrary Eulerian-Lagrangian description of motion. The referenced continuum is represented by the material points, and the motions are tracked through a computational background mesh, that is an arbitrary constant mesh which does not move the material. Hence, in the MPM mesh distortion especially in the large deformation analysis is naturally avoided. However, MPM has been employed to simulate difficult problems in the literature, many are still unsatisfactory due to the lack of rigorous validation. Therefore, this thesis firstly provides a series of simple case studies which any numerical method must pass to test the validity of the MPM, and secondly demonstrate the capability of the MPM in simulating difficult problems such as degradation of highly swellable polymers during large swelling that is currently difficult to handle by the standard finite element method. Flory’s theory is incorporated into the material point method to study large swelling of polymers, and degradation of highly swellable polymers is modelled by the MPM as a random phenomenon based on the normal distribution of the volumetric strain. These numerical developments represent adaptability of the MPM and enabling the method to be used in more complicated simulations. Furthermore, the advantages of this powerful numerical tool are studied in the modelling of an additive manufacturing technology called Selective Laser Melting (SLM). It is shown the MPM is an ideal numerical method to study SLM manufacturing technique. The focus of this thesis is to validate the MPM and exhibit the simplicity, strength, and accuracy of this numerical tool compared with standard finite element method for very complex problems which requires a complicated topological system.

Ansiedade e atenção são dois conceitos complexos, que se relacionam diretamente em função de estratégias adaptativas relacionadas à sobrevivência em seres humanos. A presente tese teve como objetivo investigar se as ansiedades de traço e de estado estariam relacionadas ao viés de atenção nos canais visual ou auditivo em uma amostra não clínica. Os capítulos apresentam experimentos com a Visual Probe Detection Task, a Escuta Dicótica e o Stroop Emocional. Todos os experimentos foram realizados em população não clínica e comparou os resultados do cálculo do viés de atenção em grupos definidos pelos escores no inventário de ansiedade de traço e de estado. Foi observada a ausência de relação entre a ansiedade de traço e de estado com o viés de atenção nestes experimentos. A falta de especificidade cognitiva dos estímulos que compõem os três experimentos foi proposta como a causa principal destes resultados. / Anxiety and attention are two complex concepts that relate directly because of adaptive strategies related to survival in humans. This doctoral thesis addressed some aspects related to these two issues. It were discussed some aspects of trait and state anxiety and the study of attentional bias in visual and auditory channels. The chapters present the empirical results of the experiments that used the Visual Probe Detection Task, the Dichotic Listening Task and the Emotional Stroop Task. All experiments were performed in non-clinical population and related the results of the evaluation of attentional bias scores with trait and state anxiety. The results showed no relationship between trait and state anxiety with the attentional bias. It discusses possible reasons for this lack of bias in these samples. Among the possibilities, the lack of cognitive specificity of stimuli that make up the three experiments was proposed as the main reason for it.