We study a discrete time, structured population dynamic model that is motivated by recent field observations concerning certain life history strategies of colonial- nesting gulls, specifically the glaucouswinged gull ( Larus glaucescens). The model focuses on mechanisms hypothesized to play key roles in a population's response to degraded environment resources, namely, increased cannibalism and adjustments in reproductive timing. We explore the dynamic consequences of these mechanics using a juvenile- adult structure model. Mathematically, the model is unusual in that it involves a high co- dimension bifurcation at R0 = 1 which, in turn, leads to a dynamic dichotomy between equilibrium states and synchronized oscillatory states. We give diagnostic criteria that determine which dynamic is stable. We also explore strong Allee effects caused by positive feedback mechanisms in the model and the possible consequence that a cannibalistic population can survive when a non- cannibalistic population cannot.

En orthodontie, le diagnostic et la planification d'un traitement reposent sur la connaissance de l'architecture dentaire du patient relevée, entre autre, par un moulage en plâtre. Aujourd’hui, des logiciels permettent de manipuler des modèles numériques des arcades dentaires obtenus après numérisation des moulages. Afin d’observer l’engrènement des dents, il est nécessaire de mettre en occlusion les deux arcades numérisées séparément. Cette étape est actuellement manuelle et l’objet de ces travaux de thèse est de proposer une chaîne robuste de traitements permettant un recalage automatique des deux arcades guidé par plusieurs photos "en bouche" du patient. L'approche proposée consiste à définir trois types de points singuliers et à mettre en place des méthodes robustes de détection automatique à la fois sur les modèles 3D et les images couleur s’appuyant sur la courbure et la texture. Une fois mis en correspondance, ces points homologues 2D/3D permettent d'estimer les matrices de projection puis la transformation rigide (6ddl) pour positionner au mieux la mandibule par rapport au maxillaire en minimisant les erreurs de reprojection dans plusieurs vues. Afin de s’affranchir du bruit de détection, les positions 2D et/ou 3D des points sont améliorées au cours du processus d’optimisation. De nombreux tests sur des données virtuelles et réelles valident l'approche choisie. L’occlusion finale obtenue par recalage automatique est proche de la référence de l’expert. Les résultats sont encourageants pour fournir une alternative automatique à intégrer dans un outil d'aide au diagnostic. / In orthodontics, the diagnosis and the planning of a treatment rest on the knowledge of the dental architecture of the patient using, among others, a dental cast in plaster. Today, dedicated software allow to manipulate digital models of the dental arches obtained after digitalization of the casts. To observe the contact of teeth, it is necessary to register both arches scanned separately. This stage is at present manual and the object of this thesis research is to propose a robust chain processing allowing an automatic registration of both arches guided by several photos of the patient mouth. The proposed approach consists in defining three types of singular points and in setting up strong methods of automatic detection at the same time on the 3D models and the color images leaning on the curvature and the texture. Once put in correspondence, these 2D / 3D equivalent points allow to estimate the projection matrices then the rigid transformation (6ddl) to position at best the mandible in relation to the maxillary by minimizing the reprojection errors in several views. To free itself from the noise of detection, the 2D and/or 3D positions of the singular points are improved during the optimization process. Numerous tests on virtual and real data validate the proposed approach. The final occlusion obtained on the real data by automatic registration is close to the reference of the expert. These are encouraging results to supply an automatic alternative to be integrated into a help tool for the diagnosis.

Over the past 40 years, coral cover has reduced by as much as 80%. At the same time, Coral Reefs are coming under increasing threat from hurricanes, as climate change is expected to increase the intensity of hurricanes. Therefore, it has become increasingly important to understand the effect of hurricanes on a coral population. This Thesis focuses on the reef-building coral Montastraea annularis. This species once dominated Caribbean Coral Reefs, but is fast being replaced by faster growing more opportunistic species. It is important that the underlying dynamics of the decline is understood, if managers stand any chance of reversing this decline. The aim of this Thesis is to investigate the effect of hurricane activity on the dynamics of the reef-building coral Montastraea annularis. To achieve this the Integral Projection Model (IPM) method was adopted and the results compared to those produced using the more traditional method of Population Projection Matrix (PPM) method. The models were fitted using census data from June 1998 to January 2003, which described the area of individual coral patches on a sample of ramets on Glovers Reef, Belize. Glovers Reef is a marine reserve that lies 30km off the coast of Belize and 15km east of the main barrier reef. Three hurricanes struck Glovers Reef during the study: Hurricane Mitch (October 1998), Hurricane Keith (September 2000) and Hurricane Iris (October 2001). The data have been divided by two different methods in order to test two research questions, firstly if the initial trauma following a hurricane affects the long term dynamics of a population and, secondly, if the dynamics exhibited during a hurricane varied with hurricane strength. In this Thesis five main results are shown: 1. All models for all divisions of data are in long term decline. 2. As initial trauma increased, the long term growth rates decreased, conversely the short term extremes increased. 3. Fragmentation is more likely as patch size increased and more likely under stronger hurricanes. 4. Integral Projection Modelling painted a similar picture to Population Projection Matrix models and should be a preferred method of analysis.5. Interaction of the IPMs can be used to model the changing occurrence of hurricanes under climate change. It is shown that with increased intensity, the population could become extinct 6.3 years sooner. This research is the first step in modelling coral patch populations by the IPM method. It suggests possible functional forms and compares the results with the PPM method. Further research is required into the biological functions which drive fragmentation, the method by which large patches divide into groups of smaller patches. The conclusions from this Thesis add to the growing body of knowledge concerning the response of coral species to hurricanes, focusing on the importance of understanding patch dynamics, in order to understand colonial dynamics.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-04-25T14:30:32Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Lelio_Alejandro_Arias_Vizcaino.pdf: 1217481 bytes, checksum: 3e169ccf7afc8c3a244b8cc4a07c9cbf (MD5) / Made available in DSpace on 2017-04-25T14:30:32Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Lelio_Alejandro_Arias_Vizcaino.pdf: 1217481 bytes, checksum: 3e169ccf7afc8c3a244b8cc4a07c9cbf (MD5) Previous issue date: 2016-12-05 / FACEPE / entre as principais metodologias estatísticas, a análise de regressão é uma das formas mais efetivas para modelar dados. Neste sentido, a análise de diagnóstico é imprescindível para determinar o que poder ter acontecido no processo gerador dos dados caso os pressupostos impostos a este não sejam plausíveis. Uma das ferramentas mais úteis em diagnóstico é a avaliação dos resíduos. Neste trabalho, propomos um novo resíduo para as classes de modelos de regressão linear e não linear baseados na família exponencial com dispersão variável (Smyth (1989)). A proposta permite incorporar de forma simultânea informações relativas aos submodelos da média e da dispersão sem fazer uso de matrizes de projeção para sua padronização. Resultados de simulação e de aplicações a dados reais mostram que o novo resíduo é altamente competitivo em relação ao resíduos amplamente usados e consolidados na literatura. / In statistical methodologies, regression analysis can be a very effective way to model data. In this sense, the diagnostic analysis is needed to try to determine what might happened in the data generating process if the conditions imposed to it are not true. One of the most useful techniques to detect the goodness of fit to the model is the evaluation of residuals. In this work, we propose a new residual to the class of linear and nonlinear regression models based on exponential family with variable dispersion (Smyth (1989)). The proposal incorporates simultaneously information from the sub-models of the mean and the dispersion without using projection matrices for its standardization. Simulation resultsandapplicationsinrealdatashowthatthenewresidualishighlycompetitivewith respect to residuals widely used and established in the literature.

電腦視覺三維建模的精確度，仰賴影像中對應點的準確性。以前的研究大多採取兩張影像，透過極線轉換(epipolar transfer)取得影像間基礎矩陣(fundamental matrix)的關係，然後進行比對或過濾不良的對應點以求取精確的對應點。然極線轉換存在退化的問題，如何避免此退化問題以及降低兩張影像之間轉換錯誤的累積，成為求取精確三維建模中極待解決的課題。 本論文中，我們提出一套機制，透過三焦張量(trifocal tensor)的觀念來過濾影像間不良的對應點，提高整體對應點的準確度，從而能計算較精確的投影矩陣進行三維建模。我們由多視角影像出發，先透過Bundler求取對應點，然後採用三焦張量過濾Bundler產生的對應點，並輔以最小中值平方法(LMedS)提升選點之準確率，再透過權重以及重複過濾等機制來調節並過濾對應點，從而取得精確度較高的對應點組合，最後求取投影矩陣進行電腦視覺中的各項應用。 實作中，我們測詴了三組資料，包含一組以3ds Max自行建置的資料與兩組網路中取得的資料。我們先從三張影像驗證三焦張量的幾何特性與其過濾對應點的可行性，再將此方法延伸至多張影像，同樣也能證實透過三焦張量確實能提升對應點的準確度，甚至可以過濾出輸入資料中較不符合彼此間幾何性的影像。 / The accuracy of 3D model constructions in computer vision depends on the accuracy of the corresponding points extracted from the images. Previous studies in this area mostly use two images and compute the fundamental matrix through the use of the epipolar geometry and then proceed for corresponding point matching and filtering out the outliers in order to get accurate corresponding points. However, the epipoler transform suffers from the degenerate problems and, also, the accumulated conversion errors during the corresponding matches both will degrade the model accuracy. Solving these problems become crucial in reconstructing accurate 3D models from multiple images. In this thesis, we proposed a mechanism to obtain accurate corresponding points for 3D model reconstruction from multiple images. The concept of trifocal tensor is used to remove the outliers in order to improve the overall accuracy of the corresponding points. We first use Bundler to search the corresponding points in the feature points extracted from multiple view images. Then we use trifocal tensor to determine and remove the outliers in the corresponding points generated by Bundler. LMedS is used in these processes to improve the accuracy of the selected points. One can also improve the accuracy of the corresponding points through the use of weighting function as well as repeated filtering mechanism. With these high precision corresponding points, we can compute more accurate fundamental matrix in order to reconstruct the 3D models and other applications in computer vision. We have tested three sets of data, one of that is self-constructed data using the 3ds Max and the other two are downloaded from the internet. We started by demonstrating the geometric properties of trifocal tensor associated with three images and showed that it can be used to filter out the bad corresponding points. Then, we successfully extended this mechanism to more images and successfully improved the accuracy of the corresponding points among these images.

Le but de cette thèse est d’étudier les structures obtenues à partir des groupes de réflexion finis. Ce travail consiste en quatre articles publiés, un article soumis et un article en préparation dont les résultats partiels constituent un chapitre de cette thèse. Dans le premier article, nous présentons une réduction des orbites des groupes de Coxeter finis vers leurs sous-groupes. Nous utilisons des matrices de projection, c’est-à-dire, des applications qui transforment les racines simples d’un groupe de réflexion en les racines simples du sous-groupe associé. Les résultats présentés dans ce papier se concentrent sur les groupes finis de réflexion non crystallographiques. De plus, nous utilisons les polytopes engendrés par le groupe non crystallographique H3 pour illustrer les lois de ramification (branching rules), c’est-à-dire une réduction des orbites des groupes finis de Coxeter. Dans le deuxième article, nous étudions les polytopes avec 60 sommets engendrés par le groupe non crystallographique H3. Nous utilisons la méthode de décoration des diagrammes de Coxeter–Dynkin pour décrire leurs structures en détails et décomposer les sommets en somme des orbits de symétries de dimension inférieure. Le troisième article compare deux notations utilisées pour décrire le polyèdre engendré par le groupe de réflexion. Il s’agit du symbole de Schläfli et de la notation des points dominants. Nous y présentons les avantages de chaque méthode, expliquons les deux approches et nous les illustrons par des exemples. Dans le quatrième article, nous nous concentrons sur le graphène, c’est-à-dire un pavement d’hexagones sur le plan, qui possède de remarquables propriétés quand les sommets sont modélisés par des atomes de carbone. Dans ce travail, nous présentons différentes méthodes pour obtenir du graphène à partir de réseaux (lattices) et des orbites de dimension 3 des groupes finis de réflexion. De plus, une technique de coloriage des hexagones au moyen d’un nombre fini de couleurs est donnée avec une méthode systématique pour raffiner le graphène. Dans le cinquième article, nous utilisons des v fonctions spéciales et les transformations de Fourier pour traiter les données échantillonnées sur un réseau de carrés du groupe de Lie SU(2)×SU(2), relié au groupe de symétrie A1×A1. / The goal of this thesis is to study structures obtained from finite reflection groups. The work is contained in four published papers, one submitted article and a research paper currently in preparation, with partial results presented as a chapter of this thesis. In the first article, we present a reduction of the orbits of finite Coxeter groups to their subgroups. We use projection matrices, that is, mappings that transform the simple roots of a reflection group to the simple roots of the appropriate subgroup. The results presented in this paper focus on non-crystallographic finite reflection groups. Moreover, we use polytopes generated by the non-crystallographic group H3 to illustrate the obtained branching rules, i.e., reductions of orbits of the finite Coxeter groups. In the second article, we study polytopes with 60 vertices, generated by the non-crystallographic group H3. We use a method of decoration of the Coxeter–Dynkin diagram to describe their structure in detail, and decompose their vertices into sums of orbits of lower-dimensional symmetries. The third article compares two notations used to describe polyhedra generated by reflection groups, namely the Schläfli symbol, and the dominant point notation. Here, we present the advantages of each method, we explain the two approaches, and we illustrate them through examples. In the fourth article, we focus on graphene, i.e., a hexagonal tiling of the plane that possesses remarkable properties when the vertices are modelled with carbon atoms. In this work, we present different methods to obtain graphene from lattices and three-dimensional orbits of finite reflection groups. Moreover, a technique to colour the hexagons by a finite number of colours is provided, along with a systematic method to refine the graphene. In the fifth article, we use special functions and Fourier transforms to process data sampled on a square lattice of the Lie group SU(2) × SU(2), related to the A1 × A1 symmetry group.

Multivariate linear regression methods are widely used statistical tools in data analysis, and were developed when some response variables are studied simultaneously, in which our aim is to study the relationship between predictor variables and response variables through the regression coefficient matrix. The rapid improvements of information technology have brought us a large number of large-scale data, but also brought us great challenges in data processing. When dealing with high dimensional data, the classical least squares estimation is not applicable in multivariate linear regression analysis. In recent years, some approaches have been developed to deal with high-dimensional data problems, among which dimension reduction is one of the main approaches. In some literature, random projection methods were used to reduce dimension in large datasets. In Chapter 2, a new random projection method, with low-rank matrix approximation, is proposed to reduce the dimension of the parameter space in high-dimensional multivariate linear regression model. Some statistical properties of the proposed method are studied and explicit expressions are then derived for the accuracy loss of the method with Gaussian random projection and orthogonal random projection. These expressions are precise rather than being bounds up to constants. In multivariate regression analysis, reduced rank regression is also a dimension reduction method, which has become an important tool for achieving dimension reduction goals due to its simplicity, computational efficiency and good predictive performance. In practical situations, however, the performance of the reduced rank estimator is not satisfactory when the predictor variables are highly correlated or the ratio of signal to noise is small. To overcome this problem, in Chapter 3, we incorporate matrix projections into reduced rank regression method, and then develop reduced rank regression estimators based on random projection and orthogonal projection in high-dimensional multivariate linear regression models. We also propose a consistent estimator of the rank of the coefficient matrix and achieve prediction performance bounds for the proposed estimators based on mean squared errors. Envelope technology is also a popular method in recent years to reduce estimative and predictive variations in multivariate regression, including a class of methods to improve the efficiency without changing the traditional objectives. Variable selection is the process of selecting a subset of relevant features variables for use in model construction. The purpose of using this technology is to avoid the curse of dimensionality, simplify models to make them easier to interpret, shorten training time and reduce overfitting. In Chapter 4, we combine envelope models and a group variable selection method to propose an envelope-based sparse reduced rank regression estimator in high-dimensional multivariate linear regression models, and then establish its consistency, asymptotic normality and oracle property. Tensor data are in frequent use today in a variety of fields in science and engineering. Processing tensor data is a practical but challenging problem. Recently, the prevalence of tensor data has resulted in several envelope tensor versions. In Chapter 5, we incorporate envelope technique into tensor regression analysis and propose a partial tensor envelope model, which leads to a parsimonious version for tensor response regression when some predictors are of special interest, and then consistency and asymptotic normality of the coefficient estimators are proved. The proposed method achieves significant gains in efficiency compared to the standard tensor response regression model in terms of the estimation of the coefficients for the selected predictors. Finally, in Chapter 6, we summarize the work carried out in the thesis, and then suggest some problems of further research interest. / Dissertation / Doctor of Philosophy (PhD)