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The mean field analysis of stochastic dynamical system allows us to gain insight into the qualitative features of their complex behavior, as well as quantitative estimates of certain aspects of their coarse-grained properties. As such, it usually furnishes a first front in approaching new dynamical systems and informs us about their stability landscape in the absence of fluctuations among other things. A knowledge of this landscape can be a valuable tool in model building for describing real world systems and provides a guiding principle for a justifiable choice of form and model parameters. In this work, we contribute to this analysis for two generic classes of high-dimensional models that possess a cyclic symmetry in the network that specifies their stochastic dynamics at the microscopic level. Our analysis is carried out in a manner that can be readily adapted for the mean field analysis of further generalized models that possess this symmetry. Moreover, in the second class of these models, we propose a new basic process that can change the stability landscape of an existing model and, as such, endow us with potential alternatives to model systems with robust biodiverse regimes. / Ph. D.

Survival Analysis generally uses the median survival time as a common summary statistic. While the median possesses the desirable characteristic of being unbiased, there are times when it is not the best statistic to describe the data at hand. Royston and Parmar (2011) provide an argument that the restricted mean survival time should be the summary statistic used when the proportional hazards assumption is in doubt. Work in Restricted Means dates back to 1949 when J.O. Irwin developed a calculation for the standard error of the restricted mean using Greenwood’s formula. Since then the development of the restricted mean has been thorough in the literature, but its use in practical analyses is still limited. One area that is not well developed in the literature is the choice of the time point to which the mean is restricted. The aim of this dissertation is to develop a data driven method that allows the user to find a cut-point to use to restrict the mean. Three methods are developed. The first is a simple method that locates the time at which the maximum distance between two curves exists. The second is a method adapted from a Renyi-type test, typically used when proportional hazards assumptions are not met, where the Renyi statistics are plotted and piecewise regression model is fit. The join point of the two pieces is where the meant will be restricted. Third is a method that applies a nonlinear model fit to the hazard estimates at each event time, the model allows for the hazards between the two groups to be different up until a certain time, after which the groups hazards are the same. The time point where the two groups’ hazards become the same is the time to which the mean is restricted. The methods are evaluated using MSE and bias calculations, and bootstrap techniques to estimate the variance.

For individuals with type 2 diabetes, diabetic foot ulcers represent a significant health issue and the wound care cost is quite high. Currently, clinicians and nurses mainly base their wound assessment on visual examination of wound size and the status of the wound tissue. This method is potentially inaccurate for wound assessment and requires extra clinical workload. In view of the prevalence of smartphones with high resolution digital camera, assessing wound healing by analyzing of real-time images using the significant computational power of today’s mobile devices is an attractive approach for managing foot ulcers. Alternatively, the smartphone may be used just for image capture and wireless transfer to a PC or laptop for image processing. To achieve accurate foot ulcer image assessment, we have developed and tested a novel automatic wound image analysis system which accomplishes the following conditions: 1) design of an easy-to-use image capture system which makes the image capture process comfortable for the patient and provides well-controlled image capture conditions; 2) synthesis of efficient and accurate algorithms for real-time wound boundary determination to measure the wound area size; 3) development of a quantitative method to assess the wound healing status based on a foot ulcer image sequence for a given patient and 4) design of a wound image assessment and management system that can be used both in the patient’s home and clinical environment in a tele-medicine fashion. In our work, the wound image is captured by the camera on the smartphone while the patient’s foot is held in place by an image capture box, which is specially design to aid patients in photographing ulcers occurring on the sole of their feet. The experimental results prove that our image capture system guarantees consistent illumination and a fixed distance between the foot and camera. These properties greatly reduce the complexity of the subsequent wound recognition and assessment. The most significant contribution of our work is the development of five different wound boundary determination approaches based on different computer vision algorithms. The first approach employs the level set algorithm to determine the wound boundary directly based on a manually set initial curve. The second and third approaches are the mean-shift segmentation based methods augmented by foot outline detection and analysis. These two approaches have been shown to be efficient to implement (especially on smartphones), prior-knowledge independent and able to provide reasonably accurate wound segmentation results given a set of well-tuned parameters. However, this method suffers from the lack of self-adaptivity due to the fact that it is not based on machine learning. Consequently, a two-stage Support Vector Machine (SVM) binary classifier based wound recognition approach is developed and implemented. This approach consists of three major steps 1) unsupervised super-pixel segmentation, 2) feature descriptor extraction for each super-pixel and 3) supervised classifier based wound boundary determination. The experimental results show that this approach provides promising performance (sensitivity: 73.3%, specificity: 95.6%) when dealing with foot ulcer images captured with our image capture box. In the third approach, we further relax the image capture constraints and generalize the application of our wound recognition system by applying the conditional random field (CRF) based model to solve the wound boundary determination. The key modules in this approach are the TextonBoost based potential learning at different scales and efficient CRF model inference to find the optimal labeling. Finally, the standard K-means clustering algorithm is applied to the determined wound area for color based wound tissue classification. To train the models used in the last two approaches, as well as to evaluate all three methods, we have collected about 100 wound images at the wound clinic in UMass Medical School by tracking 15 patients for a 2-year period, following an IRB approved protocol. The wound recognition results were compared with the ground truth generated by combining clinical labeling from three experienced clinicians. Specificity and sensitivity based measures indicate that the CRF based approach is the most reliable method despite its implementation complexity and computational demands. In addition, sample images of Moulage wound simulations are also used to increase the evaluation flexibility. The advantages and disadvantages of three approaches are described. Another important contribution of this work has been development of a healing score based mechanism for quantitative wound healing status assessment. The wound size and color composition measurements were converted to a score number ranging from 0-10, which indicates the healing trend based on comparisons of subsequent images to an initial foot ulcer image. By comparing the result of the healing score algorithm to the healing scores determined by experienced clinicians, we assess the clinical validity of our healing score algorithm. The level of agreement of our healing score with the three assessing clinicians was quantified by using the Kripendorff’s Alpha Coefficient (KAC). Finally, a collaborative wound image management system between the PC and smartphone was designed and successfully applied in the wound clinic for patients’ wound tracking purpose. This system is proven to be applicable in clinical environment and capable of providing interactive foot ulcer care in a telemedicine fashion.

No description available.

A major upgrade to the wastewater treatment plant in Saskatoon, Canada significantly improved the final effluent quality. Consequently, the relative impact of the citys urban runoff on the receiving stream, the South Saskatchewan River, has increased. Moreover, at the inception of the study, pending amendments to provincial legislation governing urban runoff were such that urban runoff would no longer be automatically exempt from regulation. In response to this impending change, which has since been made, Saskatchewan Environment initiated a study to examine the water quality of the urban runoff in Saskatoon, because little had been done to date involving the water quality of urban runoff in Saskatchewan.<p>The field program was conducted in 2001 and 2002 to collect representative urban runoff water quality and flow rate data from four different land uses: newer residential, older residential, commercial, and industrial. Three characterizations of the water quality were developed on the basis of the data collected: Site Mean Concentration (SMC), multiple variable regression models, and the unit load. The SMC results indicate that the average water quality parameter concentrations in Saskatoon are greater than those from NURP, the updated U.S. nationwide urban runoff database, and from Vancouver, Canada, but are similar to those from Wisconsin. The regression analyses indicate that the rainfall depth is the most frequently significant parameter in the prediction of event loads. The unit load analyses indicate that the commercial catchment produces the most pollutant load per unit area. Comparison of the methods indicates that the SMC can be used to estimate longer term urban runoff loads, in lieu of the more complex regression method.<p>Heavy metals, pesticides, and fecal coliforms were detected in the urban runoff at concentrations that exceed guideline values. Further investigation is recommended.<p>In comparison to the loads discharged by local point sources, urban runoff contributes larger total suspended solids (TSS) and total Kjeldahl nitrogen (TKN) loads to the South Saskatchewan River. The load of COD to the river is comparable to that of the Saskatoon Wastewater Treatment Plant (WWTP). The total phosphorus load contributed by urban runoff is slightly smaller than that of the WWTP. Considering the relative load of TSS from urban runoff to the WWTP and the potential for other, more toxic pollutants to adsorb to the TSS, sediment controls should be implemented at all levels of development. Further examination of urban runoff with specific emphasis on spring and winter runoff is recommended.

Submitted by ANA KARLA PEREIRA RODRIGUES (anakarla_@hotmail.com) on 2017-08-29T14:23:53Z No. of bitstreams: 1 arquivototal.pdf: 1435272 bytes, checksum: c4761d1ead518c5fc147deba16a17059 (MD5) / Approved for entry into archive by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2017-08-29T15:43:00Z (GMT) No. of bitstreams: 1 arquivototal.pdf: 1435272 bytes, checksum: c4761d1ead518c5fc147deba16a17059 (MD5) / Made available in DSpace on 2017-08-29T15:43:01Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1435272 bytes, checksum: c4761d1ead518c5fc147deba16a17059 (MD5) Previous issue date: 2015-08-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The familyofmetallicmeanswasintroducedbytheArgentinemathematicsVera Spinadel, in1994.Themetallicmeansareunknown,exceptfortheGoldenMean. However,othermetallicmeansalsohavepropertiesandimportantapplications.The ContinuedFractionsenableanotherwaytorepresentthesenumbers,whichareir- rational. / A famíliadosnúmerosmetálicosfoiintroduzidapelamatemáticaargentinaVera de Spinadel,em 1994. OsNúmerosMetálicossãopoucoconhecidos,comexceçãodo Número deOuro.Porém,outrosnúmerosmetálicostambémpossuempropriedades e aplicaçõesimportantes.AsFraçõesContínuaspossibilitamumaoutramaneirade representaressesnúmeros,quesãoirracionais.

Pøedlo¾ená práce se zabývá dvìma pøístupy øe¹ení problému volby portfolia. Prvním jsou čmean-riskÿ modely, které minimalizují riziko pro pøedem zvolený výnos nebo maximalizují výnos pro pevnì stanovené riziko. Druhým je princip stochastické dominance, úzce související s teorií u¾itku. Cílem této diplomové práce je zkoumat vztah mezi mno¾inami e cientních portfolií, které jsou øe¹e- ním v obou pøístupech. Pro kvanti kaci rizika se kromì základních mìr jako jsou rozptyl, V aR nebo CV aR v práci uva¾ují i spektrální míry, zohledòující sub- jektivní postoj investora k riziku. Uká¾eme, za platnosti jakých podmínek jsou modely minimalizující spektrální míry konzistentní se stochastickou dominancí druhého øádu (SSD). Aplikujeme Kopa-Postùv test, který je jedním z více testù na SSD e cienci portfolia, na reálná data z americké burzy cenných papírù a SSD e cientní portfolia porovnáme s e cientními portfoliami získanými minimalizací CV aR-u uva¾ovaného na rùznych hladinách spolehlivosti. 1