Polaris the Cepheid has been observed for centuries, presenting surprises and changing our view of Cepheids and stellar astrophysics, in general. Specifically, understanding Polaris helps anchor the Cepheid Leavitt law, but the distance must be measured precisely. The recent debate regarding the distance to Polaris has raised questions about its role in calibrating the Leavitt law and even its evolutionary status. In this work, I present new stellar evolution models of Cepheids to compare with previously measured CNO abundances, period change and angular diameter. Based on the comparison, I show that Polaris cannot be evolving along the first crossing of the Cepheid instability strip and cannot have evolved from a rapidly-rotating main sequence star. As such, Polaris must also be at least 118 pc away and pulsates in the first overtone, disagreeing with the recent results of Turner et al. (2013, ApJ, 762, L8).

Lors de dette dernière décennie, l'évolution des technologies a permis le développement de drones de taille et de poids réduit aptes à évoluer dans des environnements intérieurs ou urbains. Pour exécuter les missions qui leur sont attribuées, les drones doivent posséder un système de navigation robuste, comprenant, notamment, une fonctionnalité temps réel d'ego-localisation précise dans un repère absolu. Nous proposons de résoudre cette problématique par la mise en correspondance des dernières images acquises avec des images géoréférencées de type Google Streetview.Dans l'hypothèse où il serait possible pour une image requête de retrouver l'image géo-référencée représentant la même scène, nous avons tout d'abord étudié une solution permettant d'affiner la localisation grâce à l'estimation de la pose relative entre ces deux images. Pour retrouver l'image de la base correspondant à une image requête, nous avons ensuite étudié et proposé une méthode hybride exploitant à la fois les informations visuelles et odométriques mettant en oeuvre une chaîne de Markov à états cachés. Les performances obtenues, dépendant de la qualité de la mesure de similarité visuelle, nous avons enfin proposé une solution originale basée sur l'apprentissage supervisé de distances permettant de mesurer les similarités entre les images requête et les images géoréférencées proches de la position supposée. / In this last decade, technology evolution has enabled the development of small and light UAV able to evolve in indoor and urban environments. In order to execute missions assigned to them, UAV must have a robust navigation system, including a precise egolocalization functionality within an absolute reference. We propose to solve this problem by mapping the latest images acquired with geo-referenced images, i.e. Google Streetview images.In a first step, assuming that it is possible for a given query image to retrieve the geo-referenced image depicting the same scene, we study a solution, based on relative pose estimation between images, to refine the location. Then, to retrieve geo-referenced images corresponding to acquired images, we studied and proposed an hybrid method exploiting both visual and odometric information by defining an appropriate Hidden Markov Model (HMM), where states are geographical locations. The quality of achieved performances depending of visual similarities, we finally proposed an original solution based on a supervised metric learning solution. The solution measures similarities between the query images and geo-referenced images close to the putative position, thanks to distances learnt during a preliminary step.

Bakgrund: Vad en ledare är stämmer överens människor och kulturer emellan, men däremot vad som förväntas av en ledare och hur en ledare anses ska bete sig skiljer sig åt. När ledare från en kultur ska integreras med ett interkulturellt team är det inte en självklarhet att det går ihop. I Sverige lever människor i ett demokratiskt samhälle, vilket inte är en självklarhet i andra länder. Svenska organisationer bedrivs mer decentraliserade och medarbetare får ett större utrymme att föra en kommunikation med ledare och chefer. När svenska ledare ska arbeta med interkulturella team dyker både utmaningar och möjligheter upp. Syfte: Det övergripande syftet i studien är att undersöka vilka utmaningar en svensk ledare som är verksam inom eller över ett internationellt team kan stöta på och hur dessa uppkommer. Det är utifrån det svenska perspektivet samt ledarskapsperspektivet vi undersöker vad för slags inverkan varierande kulturer kan ha på relationer och samarbete i interkulturella team. Metod: Det har använts en kvalitativ forskningsmetod för studien. Semistrukturerade intervjuer har genomförts med sex stycken respondenter där fem av dem kommer från Sverige och en från Sri Lanka där alla har en form av ledarposition. Empiri & slutsats: Studien visar att interkulturella team skiljer sig åt mellan Sverige och icke-nordiska länder, det är tydligt att det skiljer sig åt mellan ledarskap och chefskap. Där chefskapet är mer dominerande i andra länder, vilket även Kotter påtalar. Även kulturella distanser i form av maktdistans och maskulint förhållningssätt är de som skiljer de olika kulturerna åt allra mest. Vad som är avgörande för framgång som ledare över ett interkulturellt team är att vara medveten om alla de olika kulturerna inom ett arbetslag och veta hur distanserna hanteras och kommuniceras. / Background: What a leader is consistent across people and cultures, but what is expected of a leader and how a leader is perceived to behave differ. When leaders from one culture are to be integrated with an intercultural team, it is not obvious that it will go together. In Sweden, people live in a democratic society, which is not a matter of course in other countries. Swedish organizations are run in a more decentralized way and employees have more space to communicate with leaders and managers. When Swedish leaders have to work with intercultural teams, both challenges and opportunities appear. Purpose: The overall aim of the study is to investigate which challenges a Swedish leader who works within or across an international team may encounter and how these arise. It is from the Swedish perspective and the leadership perspective that we investigate what kind of impact varying cultures can have on relationships and cooperation in intercultural teams. Method: A qualitative research method has been used for the study. Semi-structured interviews have been conducted with six respondents, five of whom come from Sweden and one from Sri Lanka, where all have some form of leadership position. Empirical & conclusion: The study shows that intercultural teams differ between Sweden and non-Nordic countries, it is clear that there is a difference between leadership and management. Where management is more dominant in other countries, which Kotter also points out. Cultural distances in the form of power distance and masculine attitudes are also what separate the different cultures the most. What is crucial to success as a leader of an intercultural team is to be aware of all the different cultures within a work team and know how the distances are managed and communicated.

Accurate delineation of anatomical structures in the white matter of the human brain is of paramount importance for multiple applications, such as neurosurgical planning, characterization of neurological disorders, and connectomic studies. Diffusion Magnetic Resonance Imaging (dMRI) techniques can provide, in-vivo, a mathematical representation of thousands of fibers composing such anatomical structures, in the form of 3D polylines called streamlines. Given this representation, a task of invaluable interest is known as white matter bundle segmentation, whose aim is to virtually group together streamlines sharing a similar pathway into anatomically meaningful structures, called white matter bundles. Obtaining a good and reliable bundle segmentation is however not trivial, mainly because of the intrinsic complexity of the data. Most of the current methods for bundle segmentation require extensive neuroanatomical knowledge, are time consuming, or are not able to adapt to different data settings. To overcome these limitations, the main goal of this thesis is to develop a new automatic method for accurate white matter bundle segmentation, by exploiting, combining and extending multiple up-to-date supervised learning techniques. The main contribution of the project is the development of a novel streamline-based bundle segmentation method based on binary linear classification, which simultaneously combines information from atlases, bundle geometries, and connectivity patterns. We prove that the proposed method reaches unprecedented quality of segmentation, and that is robust to a multitude of diverse settings, such as when there are differences in bundle size, tracking algorithm, and/or quality of dMRI data. In addition, we show that some of the state-of-the-art bundle segmentation methods are deeply affected by a geometrical property of the shape of the bundles to be segmented, their fractal dimension. Important factors involved in the task of streamline classification are: (i) the need for an effective streamline distance function and (ii) the definition of a proper feature space. To this end, we compare some of the most common streamline distance functions available in the literature and we provide some guidelines on their practical use for the task of supervised bundle segmentation. Moreover, we investigate the possibility to include, in a streamline-based segmentation method, additional information to the typically employed streamline distance measure. Specifically, we provide evidence that considering additional anatomical information regarding the cortical terminations of the streamlines and their proximity to specific Regions of Interest (ROIs) helps to improve the results of bundle segmentation. Lastly, significant attention is paid to reproducibility in neuroscience. Following the FAIR (Findable, Accessible, Interoperable and Reusable) Data Principles, we have integrated our pipelines of analysis into an online open platform devoted to promoting reproducibility of scientific results and to facilitating knowledge discovery.

Este estudo teve como objetivo o desenvolvimento de procedimentos para estimar distâncias de viagens intrazonais com base em dados de pesquisas origem-destino (O/D). A análise conduzida na aplicação apresentada foi baseada em dados de uma pesquisa O/D realizada na cidade de São Carlos, Brasil. A área urbana foi subdividida várias vezes para produzir 471 zonas de análise de tráfego (TAZ) para análise. A análise partiu da identificação de características geométricas das zonas de análise de tráfego (TAZ) que podem influenciar as distâncias das viagens intrazonais. Em seguida, indicadores numéricos dos padrões geométricos selecionados foram comparados com os valores médios das distâncias intrazonais, a fim de procurar por evidências de correlação entre estas variáveis. Duas abordagens analíticas foram exploradas: i) contínua e ii) descontínua. No primeiro caso, todas as viagens foram consideradas em um único conjunto de dados, enquanto que no segundo caso, o conjunto de dados foi dividido em dois subgrupos com características homogêneas. Os conjuntos de dados com maior correlação foram usados para construir modelos globais e estratificados para estimar distâncias intrazonais. Nos modelos globais, viagens a pé, de bicicleta e de automóvel foram analisadas como uma única base de dados. Nos modelos estratificados, os três modos de transporte foram considerados separadamente. Foram ajustados, também, modelos adicionais que permitam estimar as viagens por um modo de transporte específico a partir de valores globais de distâncias intrazonais. Os valores obtidos com estes modelos foram então comparados com as estimativas de outros modelos encontrados na literatura. Os modelos descontínuos aqui obtidos superaram claramente os modelos tradicionais. Isto sugere que podem constituir alternativas para substituir os modelos tradicionais para estimar distâncias médias de viagens intrazonais, pelo menos no caso das cidades médias brasileiras. / This study aimed at the development of procedures for estimating intrazonal trip distances based on data of origin-destination (O/D) surveys. The analysis conducted in the application presented was based on an O/D survey conducted in the city of São Carlos, Brazil. The urban area was subdivided several times to produce 471 traffic analysis zones (TAZ) for analysis. Geometrical characteristics of the zones that can influence the distances of intrazonal trips were then identified. Next, numerical indicators of the selected geometrical patterns were compared with the average values of intrazonal trip distances in order to look for evidences of correlation between these variables. Two analytical approaches were explored: i) continuous and ii) discontinuous. In the first case, all trips were consideredas a single dataset, whereas in the second case the dataset was split in two subsets with homogeneous characteristics. The datasets with higher correlation were used to build global and stratified models for estimating intrazonal trip distances. In the global models, walking, cycling, and auto trips were all considered as part of a common dataset. In the stratified models, the three transport modes were separately taken into account. Additional models, which were meant to estimate trips per mode based on global values of intrazonal trip distances, were also developed. The values obtained with these models were then compared with the estimations of other models found in the literature. The discontinuous models calibrated in this study clearly outperformed the traditional models. This may be an indication that they can be used to replace the traditional models for estimating average intrazonal trip distances, at least in the case of Brazilian medium-sized cities.

Para um espaço localmente compacto de Hausdorff K e um espaço de Banach X, denotamos por C0(K,X) o espaço de todas as funções a valores em X contínuas sobre K que se anulam no infinito, munido da norma do supremo. No espírito do clássico teorema de Banach-Stone 1937, estabelecemos que se C0(K1,X) é isomorfo a C0(K2,X), onde X é um espaço de Banach de cotipo finito e tal que X é separável ou X* tem a propriedade de Radon-Nikodým, então ou K1 e K2 são ambos finitos ou K1 e K2 tem a mesma cardinalidade. Trata-se de uma extensão vetorial de um resultado de Cengiz 1978, o caso escalar X = R ou X = C. Demonstramos também que se K1 e K2 são intervalos compactos de ordinais e X é um espaço de Banach de cotipo finito, então a existência de um isomorfismo T de C(K1,X) em C(K2,X) com ||T||||T-1|| < 3 implica que uma certa soma topológica finita de K1 é homeomorfa a alguma soma topológica finita de K2. Mais ainda, se Xn não contém subespaço isomorfo a Xn+1 para todo n &isin; N, então K1 é homeomorfo a K2. Em outras palavras, obtemos um teorema tipo Banach-Stone vetorial que é uma extensão de um teorema de Gordon de 1970 e ao mesmo tempo uma extensão de um teorema de Behrends e Cambern de 1988. Mostramos que se existe um isomorfismo T de C(K1) em um subespaço de C(K2,X) com ||T||||T-1|| < 3, então a cardinalidade do &alpha;-ésimo derivado de K2 ou é finita ou é maior do que a cardinalidade do &alpha;-ésimo derivado de K1, para todo ordinal &alpha;. Em seguida, seja n um inteiro positivo, &Gamma; um conjunto infinito munido da topologia discreta e X um espaço de Banach de cotipo finito. Estabelecemos que se o n-ésimo derivado de K for não vazio, então a distância de Banach-Mazur entre C0(K,X) e C0(&Gamma;,X) é maior ou igual a 2n + 1. Também demonstramos que para quaisquer inteiros positivos n e k, a distância de Banach-Mazur entre C([1,&omega;nk],X) e C0(N,X) é exatamente 2n+1. Estes resultados fornecem extensões vetoriais para alguns teoremas de Cambern de 1970. Para um ordinal enumerável &alpha;, denotando por C(&alpha;) o espaço de Banach das funções contínuas no intervalo de ordinal [1, &alpha;], obtemos cotas superiores H(n, k) e cotas inferiores G(n, k) para as distâncias de Banach-Mazur entre os espaços C(&omega;) e C(&omega;nk), 1 < n, k < &omega;, verificando H(n, k) - G(n, k) < 2. Estas estimativas fornecem uma resposta para uma questão de Bessaga e Peczynski de 1960 sobre as distâncias de Banach-Mazur entre C(&omega;) e cada um dos espaços C(&alpha;), &omega;<&alpha;<&omega;&omega;. / For a locally compact Hausdorff space K and a Banach space X, we denote by C0(K,X) the space of X-valued continuous functions on K which vanish at infinity, endowed with the supremum norm. In the spirit of the classical 1937 Banach-Stone theorem, we prove that if C0(K1,X) is isomorphic to C0(K2,X), where X is a Banach space having finite cotype and such that X is separable or X* has the Radon-Nikodým property, then either K1 and K2 are finite or K1 and K2 have the same cardinality. It is a vector-valued extension of a 1978 Cengiz result, the scalar case X = R or X = C. We also prove that if K1 and K2 are compact ordinal spaces and X is Banach space having finite cotype, then the existence of an isomorphism T from C(K1,X) onto C(K2,X) with ||T||||T-1|| < 3 implies that some finite topological sum of K1 is homeomorphic to some finite topological sum of K2. Moreover, if Xn contains no subspace isomorphic to Xn+1 for every n &isin; N, then K1 is homeomorphic to K2. In other words, we obtain a vector-valued Banach-Stone theorem which is an extension of a 1970 Gordon theorem and at same time an improvement of a 1988 Behrends and Cambern theorem. We show that if there is an embedding T of a C(K1) into C(K2,X) with ||T||||T-1|| < 3, then the cardinality of the &alpha;-th derivative of K2 is either finite or greater than the cardinality of the &alpha;-th derivative of K1, for every ordinal &alpha;. Next, let n be a positive integer, &Gamma; an infinite set with the discrete topology and X is a Banach space having finite cotype. We prove that if the n-th derivative of K is not empty, then the Banach Mazur distance between C0(K,X) and C0(&Gamma;,X) is greater than or equal to 2n + 1. Thus, we also show that for every positive integers n and k, the Banach Mazur distance between C([1,&omega;nk],X) and C0(N,X) is exactly 2n+1. These results provide vector-valued versions of some 1970 Cambern theorems. For a countable ordinal &alpha;, writing C(&alpha;) for the Banach space of continuous functions on the interval of ordinal [1, &alpha;], we give lower bounds H(n, k) and upper bounds G(n, k) on the Banach- Mazur distances between C(&omega;) and C(&omega;nk), 1 < n, k < &omega;, such that H(n, k) - G(n, k) < 2. These estimates provide an answer to a 1960 Bessaga and Peczynski question on the Banach-Mazur distances between C(&omega;) and each of the C(&alpha;) spaces, &omega;<&alpha;<&omega;&omega;.

Disposer de données dans le but de valider ou tester une approche ou un concept est d'une importance primordiale dans beaucoup de domaines différents. Malheureusement, ces données ne sont pas toujours disponibles, sont coûteuses à obtenir, ou bien ne répondent pas à certaines exigences de qualité ce qui les rend inutiles dans certains cas de figure.Un générateur automatique de données est un bon moyen pour obtenir facilement et rapidement des données valides, de différentes tailles, pertinentes et diversifiées. Dans cette thèse, nous proposons une nouvelle approche complète, dirigée par les modèles et basée sur la programmation par contraintes pour la génération de données. / Owning data is useful in many different fields. Data can be used to test and to validate approaches, algorithms and concepts. Unfortunately, data is rarely available, is cost to obtain, or is not adapted to most of cases due to a lack of quality.An automated data generator is a good way to generate quickly and easily data that are valid, in different sizes, likelihood and diverse.In this thesis, we propose a novel and complete model driven approach, based on constraint programming for automated data generation.

Este estudo teve como objetivo o desenvolvimento de procedimentos para estimar distâncias de viagens intrazonais com base em dados de pesquisas origem-destino (O/D). A análise conduzida na aplicação apresentada foi baseada em dados de uma pesquisa O/D realizada na cidade de São Carlos, Brasil. A área urbana foi subdividida várias vezes para produzir 471 zonas de análise de tráfego (TAZ) para análise. A análise partiu da identificação de características geométricas das zonas de análise de tráfego (TAZ) que podem influenciar as distâncias das viagens intrazonais. Em seguida, indicadores numéricos dos padrões geométricos selecionados foram comparados com os valores médios das distâncias intrazonais, a fim de procurar por evidências de correlação entre estas variáveis. Duas abordagens analíticas foram exploradas: i) contínua e ii) descontínua. No primeiro caso, todas as viagens foram consideradas em um único conjunto de dados, enquanto que no segundo caso, o conjunto de dados foi dividido em dois subgrupos com características homogêneas. Os conjuntos de dados com maior correlação foram usados para construir modelos globais e estratificados para estimar distâncias intrazonais. Nos modelos globais, viagens a pé, de bicicleta e de automóvel foram analisadas como uma única base de dados. Nos modelos estratificados, os três modos de transporte foram considerados separadamente. Foram ajustados, também, modelos adicionais que permitam estimar as viagens por um modo de transporte específico a partir de valores globais de distâncias intrazonais. Os valores obtidos com estes modelos foram então comparados com as estimativas de outros modelos encontrados na literatura. Os modelos descontínuos aqui obtidos superaram claramente os modelos tradicionais. Isto sugere que podem constituir alternativas para substituir os modelos tradicionais para estimar distâncias médias de viagens intrazonais, pelo menos no caso das cidades médias brasileiras. / This study aimed at the development of procedures for estimating intrazonal trip distances based on data of origin-destination (O/D) surveys. The analysis conducted in the application presented was based on an O/D survey conducted in the city of São Carlos, Brazil. The urban area was subdivided several times to produce 471 traffic analysis zones (TAZ) for analysis. Geometrical characteristics of the zones that can influence the distances of intrazonal trips were then identified. Next, numerical indicators of the selected geometrical patterns were compared with the average values of intrazonal trip distances in order to look for evidences of correlation between these variables. Two analytical approaches were explored: i) continuous and ii) discontinuous. In the first case, all trips were consideredas a single dataset, whereas in the second case the dataset was split in two subsets with homogeneous characteristics. The datasets with higher correlation were used to build global and stratified models for estimating intrazonal trip distances. In the global models, walking, cycling, and auto trips were all considered as part of a common dataset. In the stratified models, the three transport modes were separately taken into account. Additional models, which were meant to estimate trips per mode based on global values of intrazonal trip distances, were also developed. The values obtained with these models were then compared with the estimations of other models found in the literature. The discontinuous models calibrated in this study clearly outperformed the traditional models. This may be an indication that they can be used to replace the traditional models for estimating average intrazonal trip distances, at least in the case of Brazilian medium-sized cities.

L'essence de cette thèse est de produire des théorèmes de représentation et d'impossibilité pour des familles de relations de conséquence et d'opérateurs de révision. Dans un premier temps, on s'intéressera à des relations de conséquence préférentielles (au sens de Kraus, Lehmann et Magidor) et pivotantes (au sens de Makinson). Ce sont des relations plausibles (les premières ne sont pas monotones, les secondes si) conçues pour traiter des informations incomplètes. On les étudiera dans des cadres paraconsistants tels que celui de la logique de Belnap, ce qui les rendra aussi utiles pour traiter des informations incohérentes. En seconde partie, on s'intéressera à une approche à la révision des croyances introduite par Lehmann, Magidor et Schlechta. Elle est basée sur des distances entre interprétations et présente l'avantage de définir des opérateurs de révision qui se comportent bien en cas d'itération.

Ce travail de thèse traite de deux problèmes liés aux méthodes de reconstruction d'arbres phylogénétiques. Dans une première partie, nous fournissons des estimateurs consistants ainsi que des intervalles de confiance asymptotiques mathématiquement rigoureux pour le temps d'évolution de séquences d'ADN dans des modèles de substitutions plus réalistes que les modèles usuels, prenant en compte les effets de la méthylation des dinucléotides CpG dans le génome des mammifères. Dans une seconde partie, nous étendons un résultat récent de Steel et Matsen en prouvant qu'un des travers bien connu des méthodes Bayésiennes en phylogénie, appelé "star tree paradox", a en fait lieu dans un cadre plus large que celui de Steel et Matsen.