The DSM-5 Alternative Personality Disorder Model includes Personality Inventory for DSM-5 (PID-5) that assess 25 specific personality traits in 5 domains. The aim of this thesis was to evaluate the method and its clinical benefits, especially by comparing it with the IPDE structured interview method on a sample of N = 29 psychiatric patients. Quantitative analysis of the results of both methods revealed a number of statistically significant correlations between the IPDE dimensional scores and the individual PID-5 traits of corresponding disorders. For disorders equally defined by both approach, the IPDE dimensional scores and PID-5 individual traits correlated by majority. Due to the overall low prevalence of undisputed personality disorder diagnosis in the sample, a qualitative analysis of 11 selected cases was performed. This analysis revealed the overlapping of the personality traits derived from both methods in 10 of these 11 cases. The methods differ in the assignment of a specific personality disorder as a diagnosis, but this is due in particular to a different theoretical definition of the methods. Overall, the PID-5 method has been evaluated as clinically beneficial, with a promising future and wide use in clinical practice. KEYWORDS Personality disorders, diagnostics, PID-5, IPDE

abstract: Alzheimer's Disease (AD) is a progressive neurodegenerative disease accounting for 50-80% of dementia cases in the country. This disease is characterized by the deposition of extracellular plaques occurring in regions of the brain important for cognitive function. A primary component of these plaques is the amyloid-beta protein. While a natively unfolded protein, amyloid-beta can misfold and aggregate generating a variety of different species including numerous different soluble oligomeric species some of which are precursors to the neurofibrillary plaques. Various of the soluble amyloid-beta oligomeric species have been shown to be toxic to cells and their presence may correlate with progression of AD. Current treatment options target the dementia symptoms, but there is no effective cure or alternative to delay the progression of the disease once it occurs. Amyloid-beta aggregates show up many years before symptoms develop, so detection of various amyloid-beta aggregate species has great promise as an early biomarker for AD. Therefore reagents that can selectively identify key early oligomeric amyloid-beta species have value both as potential diagnostics for early detection of AD and as well as therapeutics that selectively target only the toxic amyloid-beta aggregate species. Earlier work in the lab includes development of several different single chain antibody fragments (scFvs) against different oligomeric amyloid-beta species. This includes isolation of C6 scFv against human AD brain derived oligomeric amyloid-beta (Kasturirangan et al., 2013). This thesis furthers research in this direction by improving the yields and investigating the specificity of modified C6 scFv as a diagnostic for AD. It is motivated by experiments reporting low yields of the C6 scFv. We also used the C6T scFv to characterize the variation in concentration of this particular oligomeric amyloid-beta species with age in a triple transgenic AD mouse model. We also show that C6T can be used to differentiate between post-mortem human AD, Parkinson's disease (PD) and healthy human brain samples. These results indicate that C6T has potential value as a diagnostic tool for early detection of AD. / Dissertation/Thesis / M.S. Biological Design 2013

A incorporação de novas ferramentas na área de saúde tem promovido uma grande atividade interdisciplinar. A Odontologia tem sido uma dessas áreas beneficiadas com a incorporação de novas tecnologias, principalmente, na área de detecção de cáries. Atualmente, a tecnologia para uso da fluorescência no diagnóstico da cárie utiliza apenas um comprimento de onda no espectro da fluorescência, relacionando com a intensidade, para a determinação da presença ou ausência de tecido cariado. No entanto, deve ser analisado o espectro de fluorescência como um todo e não a fluorescência em um único ponto, pois todos os comprimentos de onda na fluorescência contêm a informação mais precisa sobre a existência ou não de cárie. Neste trabalho descrevemos uma maneira de processarmos a fluorescência para diagnosticar com mais precisão a existência de cárie, para isso, estudamos o comportamento da fluorescência do esmalte e dentina sadios e dentina cariada através de duas formas de processamento dessa fluorescência, sendo primeiramente através da razão do pico elástico pelo pico inelástico e a razão da área inelástica pela área elástica. Utilizamos dentes que apresentavam esmalte e dentina sem cárie e uma face com dentina cariada que foram excitados com três fontes de laser com 442nm, 532nm e 632nm. Foi possível determinar que os três comprimentos de onda foram eficientes na detecção de cárie, porém quando os tecidos foram excitados com 442nm e 632nm os resultados apresentaram os melhores contrastes, além disso, apresentamos um segundo experimento, onde medimos a fluorescência do esmalte sadio com o aparelho comercial Diagnodent® antes e depois da irradiação com o laser de Er: YAG e mostramos que o aparelho mostra erros nessas medidas acusando cárie em esmalte sadio irradiado com o laser, isso identifica um problema quando a fluorescência é captada em um único comprimento de onda / The introduction of new tools in medicine has promoted an important interdisciplinar activity. In Dentistry, the improvement induced by this new technology is mainly observed at caries detection. Until now, the fluorescence procedure for caries detection is based on the investigation of only a specific region of the fluorescencespectrum. From this analysis the presence of caries or healthy tissues is inferred. However, all the fluorescence spectrum must be evaluated and not only a small part of it. The collected information will be important to the caries diagnosis. In this work we propose two ways to process the fluorescence spectrum in order to obtain a more accurate diagnosis. In this way, we study the fluorescence behavior of health enamel and healthy and decayed dentin. The fist way to process the fluorescence here proposed is obtained by the ratio of inelastic peak and elastic peak and the second one, the ratio of the inelastic and elastic areas. It were investigated human teeth with healthy enamel, decayed and healthy dentin surfaces at the same sample. The fluorescence was induced by three lasers excitation: 442nm, 532nm and 632nm. Ali the used wavelengths showed to be efficient for caries detection, however 442nm and 632nm presented better contrasts. A second study was performed, when the fluorescence of healthy enamel was investigated using a commercial device (Diagnodent®) previously and after Er: YAG irradiation. It was demonstrated that this device can present divergent results showing a caries diagnosis for a healthy irradiated enamel surface. This result identifies a problem when a single wavelength is evaluated from all the fluorescence spectrum

Durante o puerpério há muita incidência de doenças reprodutivas acarretando aumento do intervalo entre partos, bem como diminuição na taxa de concepção. A endometrite é uma enfermidade puerperal que se caracteriza por um processo inflamatório superficial do endométrio. Com o intuito de se obter novas ferramentas diagnósticas não invasivas, precisas e que proporcionam resultados precoce à reprodução, faz-se uso da ultrassonografia convencional associada a ferramenta Doppler que fornece informações em tempo real sobre a arquitetura vascular e os aspectos hemodinâmicos dos vasos em diversos órgãos. Este estudo tem por objetivo descrever, através da ultrassonografia Doppler, as alterações hemodinâmicas no útero de fêmeas bovinas causadas pela endometrite. Avaliou-se o trato reprodutivo feminino de vacas entre 25 a 35 dias pós-parto utilizando a vaginoscopia, ultrassonografia convencional e Doppler, além de citologia e exame microbiológico em 89 vacas Holandesas sendo 33 sadias (controle) e 56 com endometrite diagnosticadas por citologia (saudáveis <10% de polimorfonucleares). Os resultados obtidos destacam-se a que animais com endometrite apresentavam aumento de cérvix (p=0,04), e de útero representado pelo corno esquerdo (p=0,02). Porém não foi observado diferença quando comparado os escore de condição corporal (ECC). Quanto a ultrassonografia notou-se que animais com fluido intrauterino (FIU) e conteúdo heterogêneo intrauterino (CHIU) tinham endometrite (p<0,0001), além de correlação com a presença de Trueperella pyogenes e leveduras. Com o modo cores do Doppler obteve-se a vascularização de mesométrio (p=0,004) e endométrio (p=0,025) associada aendometrite. Entretanto não foi observado diferença estatística nas medidas do Doppler espectral (índice de resistividade, pulsatilidade e fluxo sanguíneo). Portanto a busca de novas técnicas, menos invasivas e de rápido resultado, como a ultrassonografia Doppler, podem fornecer respostas satisfatórias quanto a evolução de alterações uterinas e com isso associar os resultados à precocidade reprodutiva. / During the puerperium period there is a high incidence of reproductive diseases resulting in increased calving interval and decrease in conception rate. The endometritis is a postpartum disease that is characterized by a superficial inflammation of endometrium. With the aim to obtain new non-invasive and accurate diagnostic tools, that provide early results in reproduction, it is possible to be used the conventional ultrasound associated to Doppler that provides real time information about vascular architecture and hemodynamic aspects of vessels in several organs. This study aims to describe, through Doppler ultrasound, hemodynamic changes in the uterus of cows caused by endometritis. Were evaluated the female reproductive tract of 89 Holstein cows between 25 to 35 days postpartum using vaginoscopy, conventional ultrasound and Doppler, as well as cytology and microbiological examination. From the 89 animals that were studied, 33 were healthy (control) and 56 with endometritis diagnosed by cytology (healthy <10% polymorphonuclear). The obtained results show that animals with endometritis had increase in cervix (p = 0.04) and the uterus represented by left uterine horn (p = 0.02). However, it was not detected difference when compared the body condition score (BCS). About the ultrasound was noted that animals with intrauterine fluid (IUF) and intrauterine heterogeneous content (IUHC) had endometritis (p <0.0001) correlation with the presence of Trueperella pyogenes and yeasts. With the color Doppler mode it was possible to obtain the vascularization of mesometrium (p = 0.004) and endometrium (p = 0.025) associated with endometritis. However, it was not observed statistical difference in the measurements of the spectral Doppler (resistance index, pulsatility and blood flow). Therefore, the search for new techniques, less invasive and fast result, as the Doppler ultrasound can provide satisfactory answers as the evolution of uterine changes and thereby associate the results to the reproductive precocity.

Piscicultura de água doce consiste na maior produção da aquicultura mundial e o cultivo de peixes tem crescido, devido a investimento, desenvolvimento de tecnologias e à contínua expansão de espécies cultivadas. Esse aumento gerou novas possibilidades de transmissão de vírus aquáticos, fatores limitantes à produção da aquicultura. Dentre as centenas de vírus conhecidos de peixes, um dos principais, que atualmente é de preocupação internacional, é o vírus da Viremia Primaveril da Carpa (SVCV), devido a sua importância socioeconômica considerando os países afetados e o comércio internacional de animais aquáticos e seus derivados, com base na saúde e medidas preventivas. SVC é uma doença aguda causada por um rhabdovírus do gênero Vesiculovirus, que é um vírus de ácido ribonucleico (RNA) fita simples linear de aproximadamente 11 quilobases (kb) com polaridade negativa e envelopado. Diversos ensaios diagnósticos podem ser utilizados para detectar SVCV, porém, consomem tempo e não são adaptados para diagnóstico a campo. A prevenção da disseminação do vírus é crucial; portanto, maior entendimento do vírus e de sua transmissão é necessário. No presente estudo, a padronização de uma RT-nestedPCR foi realizada, cujo limite de detecção foi de 8,62 × 10-2 cópias/reação, observado após o spiking de tecidos de peixes com diluições seriadas de um controle positivo sintético. O ensaio foi aplicado a 150 amostras teciduais provenientes de 146 peixes distintos. As amostras consistiam de fragmentos de fígado, rim e baço e foram submetidas à transcrição reversa (RT), seguida pela reação em cadeia de polimerase (PCR), em configuração nested. Duas (2) amostras foram positivas para o gene G de SVCV pela RT-nestedPCR e a identidade dos produtos obtidos foi confirmada por sequenciamento direto utilizando-se o método de Sanger. Na reconstrução filogenética, as sequências obtidas formaram clado único, separado dos demais genogrupos e mesmo de sequências derivadas de outros vesiculovírus encontrados no Brasil. Esses resultados determinam a primeira detecção e caracterização moleculares de SVCV no Brasil por RT-nestedPCR e sequenciamento nucleotídico, indicando a necessidade de adoção de medidas de biosseguridade mais restritivas na produção pesqueira nacional. / Fresh-water fish farming forms the largest portion of the world aquaculture production, and the harvest of these warm-water fish is increasing, due to investment, improvement of technologies and continued expansion of cultivated species. This increase has rendered new possibilities for the transmission of aquatic viruses, which remain limiting factors for aquaculture production. Among the hundreds of known viruses of fish, one of the main viruses that are currently of international concern is the Spring Viremia of Carp virus (SVCV) due to its socio-economic importance regarding affected countries and international trade of aquatic animals and their products, on the basis of health control and preventive measures. SVC is an acute disease, caused by a rhabdovirus, belonging to the Vesiculovirus genus, and is an enveloped virus, with a linear single-strained negative-sense ribonucleic acid (RNA) of approximately 11 kilobases (kb). Several diagnostic assays are available for the detection of SVCV, but they are time-consuming and not well adapted for field diagnosis. Prevention of spreading of the virus is crucial; therefore, more understanding of the virus and its transmission is required. In this study, standardization of a RT-nestedPCR was performed, and its detection limit was of 8.62 × 10-2 copies/reaction, observed after spiking fish tissue with serial dilutions of a synthetic positive control. The assay was applied to 150 tissue samples from 146 different fish. Samples consisted of liver, kidney and spleen fragments, and underwent reverse transcription (RT) followed by the polymerase chain reaction (PCR) of a nested configuration. Two (2) tissue samples were found positive for the G gene of SVCV by RT-nestedPCR and the identity of products was confirmed by direct sequencing using the Sanger method. By phylogenetic reconstruction, the obtained sequences formed a unique clade, separating them from the other known genogroups, and even from sequences derived from other vesiculoviruses found in Brazil. These results represent the first molecular detection and characterization of SVCV in Brazil by RT-nestedPCR and nucleotide sequencing, indicating the need to adopt more stringent biosecurity measures in national fish farming production.

Abstract The aim of this research work is to develop a tool for condition monitoring of squirrel-cage motors using axial magnetic flux measurements, and to design a diagnostics system for electrical motors. The basic theory of the measurements and systems was found through literature reviews and was further developed from the experimental results of this research work. Fluxgate magnetometers and Hall effect sensors are not reliable enough for condition monitoring purposes, but measurements by flux coil sensors can reach adequate reliability. The useful frequency area of the flux coil sensor is from about 0.2 Hz to 15 kHz, an area is well applicable for condition monitoring of squirrel-cage motors. Output voltage is frequency dependent, increasing towards higher frequencies. Sufficient sensitivity is usually reached by a flux coil sensor having a diameter of about 30 cm and the number of turns of about 200. Sensitivity can be improved by increasing the diameter or number of turns of the coil. The sensor should be placed axially centred on the end of the motor, and measurements should be made with the loaded motor in steady operation. Output voltage is typically from the microvolt to millivolt level, however, installation inside the motor can increase it from tens of millivolts to some volts. The dynamic resolution requirement of measurement is about 70 dB and the highest line resolution needed for the spectrum analysis is about 3200 lines. Time base signal can be used to study rapid disturbances of flux caused by mechanical loading or switching of the frequency converter. Various motor failures cause specific variation to the frequency distribution of flux, so spectrum analysis is well applicable for condition monitoring. Reference measurement of each motor is required because stator winding factors, installation tolerances, operating conditions and mechanical load affect leakage flux. A broken rotor bar failure can be detected from the amplitude difference between the supply frequency and its rotor bar induced sideband. A broken rotor end ring failure can be detected by the amplitude difference between the slip frequency and the supply frequency. However, it was found that the stator current spectrum is a more reliable method of detecting both these rotor failures. The supply voltage asymmetry can also be evaluated by specific sidebands of axial flux. Turn to turn failure of the stator winding was most reliably detected by sidebands around the rotor slot pass frequencies. Equations for frequency converter supplied motors are the bases for similar equations, but the supply frequency is replaced by the output current frequency of the converter. The developed diagnostics system design for condition monitoring of ac motors includes stator current, flux coil, temperature, vibration, partial discharge, bearing current and voltage measurements. At the system diagnosis stage these measurable signals are divided to time base and frequency base signals and for each of them a fault indicator is determined. For flux coil measurements four fault indicators were found: rotor bar failure ratio, rotor end ring failure ratio, stator winding turn to turn ratio and supply voltage asymmetry operation ratio. With these failure indicators we determine failure location, state and cause. From this information a lifetime prediction of the motor is made. The results of this work are used to analyse flux coil measurements of squirrel-cage motors. In addition the research has led to a special application to monitor electric motors using an on-line condition monitoring system for paper machines and power plants.

Performing condition monitoring related tasks on any machinery is an essential element of their rational maintenance. Endeavours to detect an incipient fault within a system serve multiple purposes from increasing the safety of people responsible for operating the machines through decreasing the running and operational costs, allowing time to plan for the inevitable repairs and making sure that the downtime of the machine is kept to an absolute minimum. All these tasks gain extra importance in a case when machines are operated in dangerous conditions putting people's lives in potential jeopardy - for instance in the field of operating a helicopter. The robust assessment of the condition of gearboxes used by helicopters has recently been given an increased attention due to a number of accidents which followed an undetected drive train component failure. The majority of the on-board mounted condition monitoring systems use vibration response signals which are specifically processed to obtain a single number which is representative of a condition of a given monitored drive train component. Those signal processing methods are called Condition Indicators (CIs). There are a number of such CIs which are already in use and they seem to adequately indicate faults in most of the cases. However in a number of instances it has been observed that the most popular parameters like Crest Factor or FM4 failed to dependably reflect the true condition of the gear causing serious accidents, some of which resulted in a number of lives being lost. For this reason the presented research is focused on investigating the limitations of the existing CIs and designing a set of improved CIs. The development process is based on overcoming the drawbacks of thetechniques used in existing CIs combined with the intelligence gathered while analysing the acceleration vibration signals which contained a gear or a bearing fault. Five new CIs are proposed and the details of their design are documented. Both the existing and the proposed CIs are applied on the available, uncorrelated datasets. The results of the comparison show that the newly developed CIs are capable of indicating a gear or a bearing fault in a more robust and dependable fashion. Each proposed CI alone may not be the most robust indicator of the actual condition of the monitored component hence the output from all proposed CIs is combined into a single indication through use of a novel data fusion model. The Combined CI created based on the data fusion model is observed to be more robust compared to each CI alone, hence it may increase the confidence level of the decision making routine and is expected to decrease the number of false alarms. The methods of the existing CIs, the proposed CIs and the data fusion techniques as well as the results of the comparison between the different approaches are present in this thesis.

In recent years there has been an increased drive towards point of care testing (POCT), in which assays are performed at the site of the patient. This has many benefits, critically; the time for a result to be obtained will be significantly reduced, allowing for greater and more effective decision making. Many currently used bioassay methods are not affordable in resource poor areas where infectious disease is most prevalent, in order to combat this issue many research groups are attempting to miniaturise equipment for portability and make assays more affordable and therefore more accessible. With the aims of generating a new assay platform which is highly portable and affordable, the work in this thesis presents the development of several generic methods utilising nano- and micro-scale beads coated with aptamer which are then monitored interacting with target proteins with Tunable Resistive Pulse Sensing (TRPS). Aptamers are short oligonucleotide sequences which are capable of binding to a wide range of targets with high selectivity and comparable affinity to antibodies while possessing greater stability and have begun to challenge the role of antibodies. When aptamers bind a target, they often undergo a conformational change. In the assays described herein, this conformational change is key to the observed signal changes. TRPS is a pore-based system in which beads moving through a pore cause a measurable increase in resistance which can be used to derive particle size, concentration, and mobility. During the course of this thesis several template TRPS aptasensors have been developed. TRPS was successfully used to confirm the successful coating of nano- and micro-scale beads with DNA aptamers by monitoring an increase in electrophoretic mobility when the negatively charged DNA is added to the surface. Following on from this, TRPS was used to monitor the interaction of aptamer tagged beads with thrombin protein enabling thrombin detection down to 1.4 nM and the comparison of several thrombin-aptamers with results comparable to previously published SPR data. Thrombin was postulated to shield the negative DNA, resulting in a decrease in mobility, and the magnitude of this charge shielding was found to depend upon the binding mechanism of the aptamer used. This effect is not thought to be specific to our system nor to thrombin, the principles outlined here may be applied to other RPS technologies, or by interchanging of the aptamer, different proteins. In later chapters, this method is expanded to include multiplexed detection of growth factors and a significant improvement in signal. vi Following on from this, the controlled aggregation of avidin coated beads in the presence of biotinylated-BSA was explored. Factors impacting upon this assay were discussed including magnetic separation, particle size and particle concentration, and different methods of data interpretation were presented. This aggregation study identified several key parameters in the use of TRPS in aggregation assays. Using the methods outlined by the study of aggregates, a dispersion assay was then designed in which the interaction of thrombin proteins with clusters of particles brought about the release of many small particles by the disruption of double stranded DNA linkages. This dispersion assay incorporated magnetic separation to simplify the read-out and relied on measuring particle concentration rather than mobility, enabling the use of additional pressure to increase speed and ease of use. Using this method, thrombin was able to be detected down to 100 fM, a significant advancement in TRPS aptasensors.

Abstract This study concentrates on developing and tuning various oil analysis methods to meet the requirements of modern industry and environmental analytics. Oil analysis methods form a vital part of techniques used to monitor the condition of machines and may help to improve the overall equipment effectiveness value of a factory in a significant manner. Worm gears are used in various production machines, and their breakdowns may cause significant production losses. Wearing of these gears is relatively difficult to monitor with vibration analysis. Analysis of two indicator metals, copper and iron, may reveal wearing phenomena of worm gears effectively, and savings can be significant. Effective wear metal analysis requires good tools. ICP-OES with kerosene dilution is widely used in wear metal analysis, but purchasing and using of ICP-OES is expensive. A cheaper FAAS technique with similar pre-treatment of oil samples was tested and it proved to be useful especially in analyzing small amounts of samples. The accuracy of FAAS was sufficient for quantitative work in machine diagnostics and waste oil characterization. Solid debris analyses are useful in oil contamination control as well as in detection of wearing mechanisms. Membrane filtration, optical microscopy, SEM and automatic particle counting were applied in analysis of rolling and gear oils. Particle counting is an effective way to detect oil contamination, but in the studied cases even larger particles than those detected in normal ISO classes would be informative. However, membrane filtration and optical microscopy may reveal the wearing machine element exactly. Additives provide oils with desired properties thus they should be monitored intensively. A FTIR method for quantitative analysis of fatty alcohols and fatty acid esters in machinery oils was developed during this work. It has already been used successfully in quantitative and qualitative analysis of machinery oil samples. Various kinds of oils may be spilled into the soil during use and in accident situations, and they can migrate to groundwater layers. Biodegradation of oils can remove them from the soil or water completely or at least diminish the amount of harmful substances. An automatic, respirometric BOD OxiTop method was used to evaluate the biodegradability of various oils in water and soil media. The biodegradation of certain bio and mineral hydraulic oils was evaluated in groundwater, where bio oils usually biodegraded more effectively than mineral oils. The use of oils in machines weakened especially the biodegradability of bio oils. Biodegradability of bio oils was also studied in standard conditions of OECD 301 F and bio oils usually biodegraded moderately good in these conditions. The biodegradation of forestry chain oils and wood preservative oils was evaluated in forest soils. Linseed oil biodegraded moderately, but certain experimental wood preservatives biodegraded more effectively. Widely used creosote oil biodegraded in a lesser degree. Rapeseed oil-based chain oils biodegraded more effectively than corresponding tall oil.

Diagnostics and prognostics in rotating machinery is a subject of much on-going research. There are three approaches to diagnostics and prognostics. These include experience-based approaches, data-driven techniques and model-based techniques. Bayesian data-driven techniques are gaining widespread application in diagnostics and prognostics of mechanical and allied systems including slow rotating bearings, as a result of their ability to handle the stochastic nature of the measured data well. The aim of the study is to detect incipient damage of slow rotating bearings and develop diagnostics which will be robust under changing operating conditions. Further it is required to explore and develop an optimal prognostic model for the prediction of remaining useful life (RUL) of slow rotating bearings. This research develops a novel integrated nonlinear method for the effective feature extraction from acoustic emission (AE) signals and the construction of a degradation assessment index (DAI), which is subsequently used for the fault diagnostics of slow rotating bearings. A slow rotating bearing test rig was developed to measure AE data under variable operational conditions. The proposed novel DAI obtained by the integration of the PKPCA (polynomial kernel principal component analysis), a Gaussian mixture model (GMM) and an exponentially weighted moving average (EWMA) is shown to be effective and suitable for monitoring the degradation of slow rotating bearings and is robust under variable operating conditions. Furthermore, this study integrates the novel DAI into alternative Bayesian methods for the prediction of RUL. The DAI is used as input in several Bayesian regression models such as the multi-layer perceptron (MLP), radial basis function (RBF), Bayesian linear regression (BLR), Gaussian mixture regression (GMR) and the Gaussian process regression (GPR) for RUL prediction. The combination of the DAI with the GPR model, otherwise, known as the DAI-GPR gives the best prediction. The findings show that the GPR model is suitable and effective in the prediction of RUL of slow rotating bearings and robust to varying operating conditions. Further, the models are also robust when the training and tests sets are obtained from dependent and independent samples. Finally, an optimal GPR for the prediction of RUL of slow rotating bearings based on a DAI is developed. The model performance is evaluated for cases where the training and test samples from cross validation approach are dependent as well as when they are independent. The optimal GPR is obtained from the integration or combination of existing simple mean and covariance functions in order to capture the observed trend of the bearing degradation as well as the irregularities in the data. The resulting integrated GPR model provides an excellent fit to the data and improvements over the simple GPR models that are based on simple mean and covariance functions. In addition, it achieves a near zero percentage error prediction of the RUL of slow rotating bearings when the training and test sets are from dependent samples but slightly different values when the estimation is based on independent samples. These findings are robust under varying operating conditions such as loading and speed. The proposed methodology can be applied to nonlinear and non-stationary machine response signals and is useful for preventive machine maintenance purposes. Keywords: acoustic emission, Bayesian linear regression, Bayesian techniques, covariance function, data-driven, degradation assessment index, diagnostics, experience-based, exponentially weighted moving average, Gaussian mixture model, Gaussian mixture regression, Gaussian process regression, integration, mean function, model-based, multi-layer perceptron, polynomial kernel principal component analysis, prognostics, radial basis function, remaining useful life. / Thesis (PhD)--University of Pretoria, 2014. / lk2014 / Mechanical and Aeronautical Engineering / PhD / unrestricted