<p>The use of positron emission tomography (PET) in radiation therapy has continued to grow, especially since the development of combined computed tomography (CT) and PET imaging system in the early 1990s. Today, the biggest use of PET-CT is in oncology, where a glucose analog radiotracer is rapidly incorporated into the metabolic pathways of a variety of cancers. Images representing the in-vivo distribution of this radiotracer are used for the staging, delineation and assessment of treatment response of patients undergoing chemotherapy or radiation therapy. While PET offers the ability to provide functional information, the imaging quality of PET is adversely affected by its lower spatial resolution. It also has unfavorable image noise characteristics due to radiation dose concerns and patient compliance. These factors result in PET images having less detail and lower signal-to-noise (SNR) properties compared to images produced by CT. This complicates the use of PET within many areas of radiation oncology, but particularly the delineation of targets for radiation therapy and the assessment of patient response to therapy. The development of segmentation methods that can provide accurate object identification in PET images under a variety of imaging conditions has been a goal of the imaging community for years. The goal of this thesis are to: (1) investigate the effect of filtering on segmentation methods; (2) investigate whether combining individual segmentation methods can improve segmentation accuracy; (3) investigate whether the consensus volumes can be useful in aiding physicians of different experience in defining gross tumor volumes (GTV) for head-and-neck cancer patients; and (4) to investigate whether consensus volumes can be useful in assessing early treatment response in head-and-neck cancer patients.</p><p>For this dissertation work, standard spherical objects of volumes ranging from 1.15 cc to 37 cc and two irregularly shaped objects of volume 16 cc and 32 cc formed by deforming high density plastic bottles were placed in a standardized image quality phantom and imaged at two contrasts (4:1 or 8:1 for spheres, and 4.5:1 and 9:1 for irregular) and three scan durations (1, 2 and 5 minutes). For the work carried out into the comparison of images filters, Gaussian and bilateral filters matched to produce similar image signal to noise (SNR) in background regions were applied to raw unfiltered images. Objects were segmented using thresholding at 40% of the maximum intensity within a region-of-interest (ROI), an adaptive thresholding method which accounts for the signal of the object as well as background, k-means clustering, and a seeded region-growing method adapted from the literature. Quality of the segmentations was assessed using the Dice Similarity Coefficient (DSC) and symmetric mean absolute surface distance (SMASD). Further, models describing how DSC varies with object size, contrast, scan duration, filter choice and segmentation method were fitted using generalized estimating equations (GEEs) and standard regression for comparison. GEEs accounted for the bounded, correlated and heteroscedastic nature of the DSC metric. Our analysis revealed that object size had the largest effect on DSC for spheres, followed by contrast and scan duration. In addition, compared to filtering images with a 5 mm full-width at half maximum (FWHM) Gaussian filter, a 7 mm bilateral filter with moderate pre-smoothing (3 mm Gaussian (G3B7)) produced significant improvements in 3 out of the 4 segmentation methods for spheres. For the irregular objects, time had the biggest effect on DSC values, followed by contrast. </p><p>For the study of applying consensus methods to PET segmentation, an additional gradient based method was included into the collection individual segmentation methods used for the filtering study. Objects in images acquired for 5 minute scan durations were filtered with a 5 mm FWHM Gaussian before being segmented by all individual methods. Two approaches of creating a volume reflecting the agreement between the individual methods were investigated. First, a simple majority voting scheme (MJV), where individual voxels segmented by three or more of the individual methods are included in the consensus volume, and second, the Simultaneous Truth and Performance Level Estimation (STAPLE) method which is a maximum likelihood methodology previously presented in the literature but never applied to PET segmentation. Improvements in accuracy to match or exceed the best performing individual method were observed, and importantly, both consensus methods provided robustness against poorly performing individual methods. In fact, the distributions of DSC and SMASD values for the MJV and STAPLE closely match the distribution that would result if the best individual method result were selected for all objects (the best individual method varies by objects). Given that the best individual method is dependent on object type, size, contrast, and image noise and the best individual method is not able to be known before segmentation, consensus methods offer a marked improvement over the current standard of using just one of the individual segmentation methods used in this dissertation. </p><p>To explore the potential application of consensus volumes to radiation therapy, the MJV consensus method was used to produce GTVs in a population of head and neck cancer patients. This GTV and one created using simple 40% thresholding were then available to be used as a guidance volume for an attending head and neck radiation oncologist and a resident who had completed their head and neck rotation. The task for each physician was to manually delineate GTVs using the CT and PET images. Each patient was contoured three times by each physician- without guidance and with guidance using either the MJV consensus volume or 40% thresholding. Differences in GTV volumes between physicians were not significant, nor were differences between the GTV volumes regardless of the guidance volume available to the physicians. However, on average, 15-20% of the provided guidance volume lay outside the final physician-defined contour.</p><p>In the final study, the MJV and STAPLE consensus volumes were used to extract maximum, peak and mean SUV measurements in two baseline PET scans and one PET scan taken during patients' prescribed radiation therapy treatments. Mean SUV values derived from consensus volumes showed smaller variability compared to maximum SUV values. Baseline and intratreatment variability was assessed using a Bland-Altman analysis which showed that baseline variability in SUV was lower than intratreatment changes in SUV.</p><p>The techniques developed and reported in this thesis demonstrate how filter choice affects segmentation accuracy, how the use of GEEs more appropriately account for the properties of a common segmentation quality metric, and how consensus volumes not only provide an accuracy on par with the single best performing individual method in a given activity distribution, but also exhibit a robustness against variable performance of individual segmentation methods that make up the consensus volume. These properties make the use of consensus volumes appealing for a variety of tasks in radiation oncology.</p> / Dissertation

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Le Plateau des Guyanes a été géologiquement stable au cours de l'ère Cénozoïque, exempt de l'influence de l'orogénèse des Andes et de la mise en place du bassin de l'Amazone. Cette région est-elle biogéographiquement homogène au sein de l'Amazonie ? Quelles sont les modalités spatio-temporelles de diversification au sein de cette région ? Afin de répondre à ces questions, j'ai exploré sa biorégionalisation sur la base de la distribution des amphibiens anoures. Cette approche a permis de définir trois biorégions dans l'est du Plateau des Guyanes, et de révéler une forte sous-estimation de l'endémisme. Ensuite, j'ai étudié les patrons de diversification au sein du genre endémique Anomaloglossus. Ce volet a permis de dévoiler l'existence de spéciation cryptique au sein du genre, avec un patron biogéographique composé de quatre zones de diversification au sein du Plateau des Guyanes et une origine du genre dans les tepuis. / The Guiana Shield has been geologically stable during the Cenozoic era, exempt of the influence of the uplift of the Andes and the setting up of the Amazon basin. Is this region biogeographically homogeneous within Amazonia? What are the spatio-temporal diversification modalities within this region? To answer these questions, I explored bioregionalisation within Amazonia and the Guiana Shield based on the dis- tribution of anuran amphibians. This approach enabled to define three bioregions in the eastern Guiana Shield and to reveal a high underestimation of endemism. Then, I studied the diversification patterns within the endemic frog genus Anomaloglossus. This part en- abled to reveal cryptic speciation within the genus, and a biogeographic pattern composed of four areas of diversification in the Guiana Shield, with an origin of the genus in the western highlands (tepuis).

South Africa has a few unique and understudied areas of interest regarding wetlands, of which the Maputaland Coastal Plain (MCP) is one. This is regarded as a large gap in scientific knowledge, especially since firstly, the MCP is regarded as a unique area in terms of biodiversity, geology, social history, and ecosystem variety; and secondly, wetlands are a vulnerable, and yet a greatly important ecosystem type in South Africa. Additionally the wetlands on the aeolian derived sandy soils associated with the MCP are problematic to delineate. Although the wetland delineation guideline of DWAF (2005) gives a list of criteria to aid the delineation process on sandy coastal aquifers, this has never been scientifically reviewed. The aim of this study was to investigate how vegetation and soil properties vary down the topographical slope in various wetland types on the MCP. This was done in order to contribute to the knowledge base and understanding of wetlands in this area, as well as to determine whether differences between zones are significant enough to be used as indicators of wetland boundaries. Soil colour was investigated as a possible new delineation indicator. A section is also devoted to commentary on the current wetland delineation procedure on the MCP. This study shows that wetland types on the MCP are very distinct from each other, and therefore broad statements about the soil and vegetation characteristics of wetlands are discouraged. Three substrate types namely high organic-, duplex-, and sandy substrates dominate wetlands on the MCP. These play a major influential role in the general characteristics and function of the wetland types. Contrary to popular belief, redoximorphic accumulation and -depletions do occur on the MCP, but are often inconsistent in their presence. Chemical soil properties were found not to be good indicators of wetland boundaries on the MCP, although certain patterns can be discerned and applied to determine wetland conditions. The main drivers of wetland vegetation are the wetness- and productivity gradients. A few prominent indicator species can be used for the identification of wetland and non-wetland sites specifically on the MCP. Additionally, a relatively underutilised vegetation assessment procedure called Weighted Averaging was investigated, and can in most cases effectively discern between wetland and non-wetland conditions. This is a useful tool to apply in delineation practices in addition to other indicators. Soil colour can be used to successfully indicate wetland boundaries, and therefore be used as an additional wetland indicator. However, the method requires further testing and refinement for different wetland types. In general the vegetation and soil indicators do not correlate perfectly, and therefore delineation by means of one indicator only is greatly discouraged. An investigation of recommended delineation procedures for the MCP shows that new information on the understanding of wetlands in sandy coastal aquifers urgently needs to be disseminated. Approaches such as that of the USDA-NRCS where regionally specific guidelines are designed to be adapted regularly as new information becomes available, as well as the development of sets of hydric indicators specific to problematic areas, are recommended / College of Agriculture and Environmental Sciences / D. Phil. (Environmental Science)

Orientador: Gimol Benzaquen Perosa Perosa / Resumo: Ainda são escassas as pesquisas longitudinais sobre o papel da saúde mental materna, nos períodos antes e após o nascimento, no desenvolvimento do bebê e nas práticas e cuidados parentais. O objetivo deste trabalho foi estudar a associação entre os sintomas de ansiedade, estresse e depressão, desde o terceiro trimestre de gestação até 14 meses após o parto para o desenvolvimento da criança durante o primeiro ano de vida, e o papel de variáveis sociodemográficas e de práticas educativas. Participaram da primeira fase deste estudo 320 gestantes no último trimestre gestacional, usuárias do Sistema Único de Saúde, de três cidades do interior paulista. Elas responderam a uma entrevista inicial e a questionários para avaliar ansiedade (IDATE), estresse (ISSL) e depressão (BDI). Seis meses após o nascimento do bebê, a pesquisadora agendava uma visita na residência da mãe para nova avaliação. Na segunda fase, participaram 200 díades mãe-bebê. As mães responderam aos mesmos instrumentos aplicados na fase anterior e o desenvolvimento da criança foi avaliado por meio de um teste de rastreio (Escala de Denver II). Aos 14 meses, reavaliou-se o desenvolvimento de 149 crianças, as mães responderam novamente aos questionários para avaliação de saúde mental, além de um questionário de práticas de cuidados parentais e a importância atribuída a esses aspectos (E-CPPC). Primeiramente, procedeu-se à análise descritiva; em seguida, realizaram-se análises bivariadas e, com as associações significat... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Longitudinal studies about the maternal mental health’s role in the antenatal and postpartum period, during child development and in parental practice and care are still scarce. The arm of this research was to study the association between anxiety symptoms, stress and depression, since the third trimester until fourteen months after birth to the child’s development during the first year, and the role of socio demographic variables and educational practices.320 pregnant women in their last trimester, users of SUS (Brazilian National Health Program) from three São Paulo State’s cities took part in this study. They answered an initial interview and questionnaires to evaluate anxiety (IDATE), stress (ISSL) and depression (BDI).Six months after birth, the researcher would schedule an interview in the mother’s residence to reevaluate. During the second phase, 200 mother-baby dyads participated. Mothers responded to the same materials applied in the previous phase and child development was evaluated through a screening test (Denver Scale II).At 14 months, the development of 149 children was reassessed, the mothers once more answered the questionnaires to evaluation of mental health and also a questionnaire about parental care practice and attributed importance (E-CPPC). First, descriptive statistics were developed and next bivariate analysis and, with significant associations, with a p < 0.20 value logistic regressions models were built to identify risk factors and protection to men... (Complete abstract click electronic access below) / Doutor

The goal of this work is to study the principles of delineation of ECG signals, wavelet transformation and transformation approaches to increase the number of available leads. Consequently, the knowledge was used to create delineation algorithm in Matlab. The algorithm was tested on complete CSE database. The obtained results were compared with the criteria which are set for the CSE database. In this work were realized six transformation approaches to increase the number of available leads. All of them were analyzed by delineation algorithm. In the work was examined, whether the transformation increase the efficiency of detection.

This work deals with delineation of ECG signals. First we will become familiar with ECG and commonly used processing methods. Various transformation methods of ECG leads. Further we will describe methods of delineation ECG signals. Second part is dedicated to metod used in this work for delineation of ECG signals from CSE database. Particulary method using Dyadic Wavelet Transform. Work include, description of used program and results. Third part is dedicated to methods of ECG leads transformations and cluster analysis. In conclusion we will evaluate the results.

>Magister Scientiae - MSc / Understanding of Groundwater Dependent Ecosystems (GDEs) and their extent within the Table Mountain Group (TMG) aquifer is poor. To understand the dependence to basic ecological and hydrogeological concepts need explanation. The use of current literature aided in identification and classification. From the literature it has come clear that groundwater dependence centers around two issues, water source and water use determination. The use of Geographical Information System (GIS) showed its potential in proof of water sources. Rainfall data and a Digital Elevation Model (DEM) for the Uniondale area have been used to do watershed delineation, which is in line with locating GDEs on a landscape. Thus the conceptual approach should be a broad one that sets a basis for both investigation (scientific research) and institutional arrangements (management). On the scientific research aspect: 1) Methods used to ascertain groundwater dependence have been identified and described (for example morphological traits, physiological traits, etc.) a) Use of GIS to delineate watersheds in the Uniondale area, putting it as one of useful methods that can be used in locating GDEs in a landscape. b) Use of Digital Elevation Models (DEMs) to create both geological and topographic cross-sections. Topographic cross-sections are important to locate ecosystems along a landscape, while geological cross-sections are useful in conceptualising groundwater flow. 2) The Plant Functional Type concept, which puts together plant species regardless of phylogeny but rather on morphological, phenological and physiological/life history trait similarity, has been suggested as a useful concept for the TMG GDEs. On the management aspect: 1) An ecosystem approach to understand groundwater has been identified and modified to suite the TMG GDE management. 2) A retention strategy useful to manage the TMG GDEs effectively has been suggested. There are knowledge gaps that exist in the TMG aquifer about Groundwater Dependent Ecosystems. Thus there is: • A need to identify GDE types that exist based on their degrees of dependency on groundwater. • A need to classify the GDEs using a PFTconcept. • To compile a trait (morphological, phenological and physiological) database for TMG aquifer GDEs.

This research presents two approaches to determining the effects of natural variability and model uncertainty on the extents of computed floodplain boundaries. The first approach represents the floodplain boundary as a spatial map of flood probabilities -- with values between 0 and 100%. Instead of representing the floodplain boundary at a certain recurrence interval as a single line, this approach creates a spatial map that shows the probability of flooding at each point in the floodplain. This flood probability map is a useful tool for visualizing the uncertainty of a floodplain boundary. However, engineers are still required to determine a single line showing the boundary of a floodplain for flood insurance and other floodplain studies. The second approach to determining the effects of uncertainty on a floodplain boundary computes the annual exceedance probability (AEP) at each point on the floodplain. This spatial map of AEP values represents the flood inundation probability for any point on the floodplain in any given year. One can determine the floodplain boundary at any recurrence interval from this AEP map. These floodplain boundaries include natural variability and model uncertainty inherent in the modeling process. The boundary at any recurrence interval from the AEP map gives a single, definite boundary that considers uncertainty. This research performed case studies using data from Leith Creek in North Carolina and the Virgin River in southern Utah. These case studies compared a flood probability map for a certain recurrence interval with an AEP map and demonstrated the consistency of the results from these two methods. Engineers and planners can use floodplain probability maps for viewing the uncertainty of a floodplain boundary at a certain recurrence interval. They can also use AEP maps for determining a single boundary for a certain recurrence interval that considers all the natural variability and model uncertainty inherent in the modeling process.

No description available.