Dissertations / Theses on the topic 'Graphes médians'

Le problème du médian est un des problèmes les plus étudiés en théorie des espaces métriques. Nous l'étudions dans les graphes médians d'un point de vue algorithmique. Nous présentons un algorithme linéaire basé sur un calcul rapide des classes de parallélisme des arêtes (les Thêta-classes) via un parcours en largeur particulier (LexBFS). Nous donnons également un algorithme linéaire pour le problème du médian dans les l1-complexes cubiques des graphes médians et dans les structures d'évènements.Ensuite, nous présentons une caractérisation des graphes aux médians connexes dans la p-ième puissance Gp du graphe et donnons une méthode polynomiale pour vérifier si un graphe est un graphe aux médians Gp-connexes, étendant un résultat de Bandelt et Chepoi (cas p=1). Nous utilisons cette caractérisation pour montrer que certaines classes de graphes sont G2-connexes, comme les graphes de Helly bipartis et les graphes pontés. Nous travaillons également sur l'aspect axiomatique en étudiant l'ABC-problème, qui consiste à déterminer les graphes (nommés ABC-graphes) dans lesquels la fonction médian est l'unique fonction consensus respectant trois axiomes simples (A) Anonymat, (B) Intervalle (Betweeness) et (C) Cohérence. Nous montrons que les graphes modulaires aux médians G2-connexes sont des ABC-graphes et définissons de nouveaux axiomes pour caractériser la fonction médian dans d'autres classes de graphes, comme les graphes aux médians connexes. Nous prouvons également que les graphes respectant la propriété d'appariement (qui sont des ABC-graphes) est une sous-classe propre des graphes de Helly bipartis et étudions la complexité de la reconnaissance de ces graphes
The median problem is one of the most investigated problem in metric graph theory. We will start by studying this problem in median graphs. We present a linear time algorithm based on the majority rule which characterize the median in median graphs and on a fast computation of the parallelism classes of the edges (the \Theta-classes) via LexBFS which is a particular breadth first search algorithm.We also provide linear time algorithms to compute the median set in the l_1-cube complexes of median graphs and in event structures. Then, we provide a characterization of the graphs with connected medians in the pth power of the graph and provide a polynomial method to check if a graph is a G^p-connected median graph, extending a result of Bandelt and Chepoi (case p=1). We use this characterization to prove that some important graph classes in metric graph theory have G2-connected medians, such as bipartite Helly graphs and bridged graphs. We will also studied the axiomatic aspect of the median function by investigating the ABC-problem, which determine the graphs (named ABC-graphs) in which the median function is the only consensus function verifying three simples axioms (A) Anonymat, (B) Betweeness and (C) Consistency. We show that modular graphs with G2-connected medians are ABC-graphs and define new axioms allowing us to characterize the median function on some graph classes. For example the graphs with connected medians (including Helly graphs). We also show that a known class of ABC-graphs (graphs satisfying the pairing property) is a proper subclass of bipartite Helly graphs and we investigate their recognition

La notion d'intervalle dans un graphe, traduit de façon naturelle la notion du segment dans les espaces euclidiens. Par analogie, un ensemble C de sommets est convexe si pour tout couple x, y de sommets de C, l'intervalle entre x et y est inclu dans C. En utilisant la convexité géodésique, Djokovic a caractérisé les graphes isométriquement plongeable dans l'hypercube. Une vingtaine d'années plus tard, Mulder a caractérisé les graphes médians comme des graphes isométriquement plongeable dans l'hypercube et qui sont fermés pour l'opération médian. La comprehension du lien apparent entre ces deux résultats, nous a permis de trouver une nouvelle caractérisation, d'inspiration géométrique, des graphes médians. Cette caractérisation nous a permis à reconnaître les graphes médians qui sont des produits d'arbres ou de chemins. Nous avons donné une caractérisation de ces produits par mineurs convexes exclus. Un autre groupe de résultats concerne des graphes définis naturellement à partir des polyminos. En cherchant le nombre minimum de sommets qui engendrent convexement un tel graphe G, nous avons trouvé que ce nombre est égal au nombre maximum de sommets de degré un d'un arbre obtenu à partir de G par la contraction d'arêtes bien choisies

L’évolution du web, de ce qui était typiquement connu comme un moyen de communication à sens unique en mode conversationnel, a radicalement changé notre manière de traiter l’information. Des sites de médias sociaux tels que Flickr et Facebook, offrent des espaces d’échange et de diffusion de l’information. Une information de plus en plus riche, mais aussi personnelle, et qui s’organise, le plus souvent, autour d’événements de la vie réelle. Ainsi, un événement peut être perçu comme un ensemble de vues personnelles et locales, capturées par différents utilisateurs. Identifier ces différentes instances permettrait, dès lors, de reconstituer une vue globale de l’événement. Plus particulièrement, lier différentes instances d’un même événement profiterait à bon nombre d’applications tel que la recherche, la navigation ou encore le filtrage et la suggestion de contenus. L’objectif principal de cette thèse est l’identification du contenu multimédia, associé à un événement dans de grandes collections d’images. Une première contribution est une méthode de recherche d’événements basée sur le contenu visuel. La deuxième contribution est une approche scalable et distribuée pour la construction de graphes des K plus proches voisins. La troisième contribution est une méthode collaborative pour la sélection de contenu pertinent. Plus particulièrement, nous nous intéresserons aux problèmes de génération automatique de résumés d’événements et suggestion de contenus dans les médias sociaux
The ease of publishing content on social media sites brings to the Web an ever increasing amount of user generated content captured during, and associated with, real life events. Social media documents shared by users often reflect their personal experience of the event. Hence, an event can be seen as a set of personal and local views, recorded by different users. These event records are likely to exhibit similar facets of the event but also specific aspects. By linking different records of the same event occurrence we can enable rich search and browsing of social media events content. Specifically, linking all the occurrences of the same event would provide a general overview of the event. In this dissertation we present a content-based approach for leveraging the wealth of social media documents available on the Web for event identification and characterization. To match event occurrences in social media, we develop a new visual-based method for retrieving events in huge photocollections, typically in the context of User Generated Content. The main contributions of the thesis are the following : (1) a new visual-based method for retrieving events in photo collections, (2) a scalable and distributed framework for Nearest Neighbors Graph construction for high dimensional data, (3) a collaborative content-based filtering technique for selecting relevant social media documents for a given event

L’évolution du web, de ce qui était typiquement connu comme un moyen de communication à sens unique en mode conversationnel, a radicalement changé notre manière de traiter l’information. Des sites de médias sociaux tels que Flickr et Facebook, offrent des espaces d’échange et de diffusion de l’information. Une information de plus en plus riche, mais aussi personnelle, et qui s’organise, le plus souvent, autour d’événements de la vie réelle. Ainsi, un événement peut être perçu comme un ensemble de vues personnelles et locales, capturées par différents utilisateurs. Identifier ces différentes instances permettrait, dès lors, de reconstituer une vue globale de l’événement. Plus particulièrement, lier différentes instances d’un même événement profiterait à bon nombre d’applications tel que la recherche, la navigation ou encore le filtrage et la suggestion de contenus. L’objectif principal de cette thèse est l’identification du contenu multimédia, associé à un événement dans de grandes collections d’images. Une première contribution est une méthode de recherche d’événements basée sur le contenu visuel. La deuxième contribution est une approche scalable et distribuée pour la construction de graphes des K plus proches voisins. La troisième contribution est une méthode collaborative pour la sélection de contenu pertinent. Plus particulièrement, nous nous intéresserons aux problèmes de génération automatique de résumés d’événements et suggestion de contenus dans les médias sociaux
The ease of publishing content on social media sites brings to the Web an ever increasing amount of user generated content captured during, and associated with, real life events. Social media documents shared by users often reflect their personal experience of the event. Hence, an event can be seen as a set of personal and local views, recorded by different users. These event records are likely to exhibit similar facets of the event but also specific aspects. By linking different records of the same event occurrence we can enable rich search and browsing of social media events content. Specifically, linking all the occurrences of the same event would provide a general overview of the event. In this dissertation we present a content-based approach for leveraging the wealth of social media documents available on the Web for event identification and characterization. To match event occurrences in social media, we develop a new visual-based method for retrieving events in huge photocollections, typically in the context of User Generated Content. The main contributions of the thesis are the following : (1) a new visual-based method for retrieving events in photo collections, (2) a scalable and distributed framework for Nearest Neighbors Graph construction for high dimensional data, (3) a collaborative content-based filtering technique for selecting relevant social media documents for a given event

La détection d’événements dans les réseaux sociaux consiste à retrouver les traces d’événements réels dans des flux d’informations en ligne. L’ambition de notre travail est double : trouver, dans un premier temps, des événements que les principaux médias ne traitent pas et, dans un second temps, étudier l’intérêt que les utilisateurs ont pour certains types d’événements. Pour résoudre notre problème nous commençons par une caractérisation des données basée sur un graphe dans lequel les noeuds sont des mots et les arêtes représentent le nombre de cooccurrences. La densité est une très bonne mesure de l’importance et de la cohésion dans les graphes. En prenant en compte les propriétés caractéristiques des réseaux du réel, nous pouvons développer des algorithmes capables de résoudre efficacement des problèmes complexes. Les contributions de cette thèse sont : concevoir des algorithmes efficaces pour calculer différents types de sous-graphes denses dans des graphes réels, et fournir un algorithme orienté graphe efficace pour la détection d’événements
Event detection in social media is the task of finding mentions of real-world events in collections of posts. The motivation behind our work is two-folded: first, finding events that are not covered by mainstream media and second, studying the interest that users show for certain types of events. In order to solve our problem, we start from a graph based characterization of the data in which nodes represent words and edges count word co-occurrences. Density is a very good measure of importance and cohesiveness in graphs. Taking into account the special properties of real-word networks, we can develop algorithms that efficiently solve hard problems. The contributions of this thesis are: devising efficient algorithms for computing different types of dense subgraphs in real-world graphs, presenting a novel dense subgraph definition and providing an efficient graph-based algorithm for event detection

Les réseaux sociaux numériques ont pris une place prépondérante dans l'espace informationnel, et sont souvent utilisés pour la publicité, le suivi de réputation, la propagande et même la manipulation, que ce soit par des individus, des entreprises ou des états. Alors que la quantité d'information rend difficile son exploitation par des humains, le besoin reste entier d'analyser un réseau social numérique : il faut dégager des tendances à partir des messages postés dont notamment les opinions échangées, qualifier les comportements des utilisateurs, et identifier les structures sociales émergentes.Pour résoudre ce problème, nous proposons un système d'analyse en trois niveaux. Tout d'abord, l'analyse du message vise à en déterminer l'opinion. Ensuite, la caractérisation et l'évaluation des comptes utilisateurs est réalisée grâce à une étape de profilage comportemental et à l'étude de leur importance et de leur position dans des graphes sociaux, dans lesquels nous combinons les mesures topologiques d'importance des noeuds dans un graphe avec les statistiques d'engagement, par exemple en nombre d'abonnés. Enfin, le système procède à la détection et à l'évaluation de communautés d'utilisateurs, pour lesquelles nous introduisons des scores de cohésion thématique qui complètent les mesures topologiques classiques de qualité structurelle des communautés détectées. Nous appliquons ce système d'analyse sur deux corpus provenant de deux médias sociaux différents : le premier est constitué de messages publiés sur Twitter, représentant toutes les activités réalisées par 5 000 comptes liés entre eux sur une longue période. Le second provient d'un réseau social basé sur TOR, nommé Galaxy2. Nous évaluons la pertinence de notre système sur ces deux jeux de données, montrant la complémentarité des outils de caractérisation des comptes utilisateurs (influence, comportement, rôle) et des communautés de comptes (force d'interaction, cohésion thématique), qui enrichissent l'exploitation du graphe social par les éléments issus des contenus textuels échangés
Online Social Networks have taken a huge place in the informational space and are often used for advertising, e-reputation, propaganda, or even manipulation, either by individuals, companies or states. The amount of information makes difficult the human exploitation, while the need for social network analysis remains unsatisfied: trends must be extracted from the posted messages, the user behaviours must be characterised, and the social structure must be identified. To tackle this problem, we propose a system providing analysis tools on three levels. First, the message analysis aims to determine the opinions they bear. Then, the characterisation and evaluation of user accounts is performed thanks to the union of a behavioural profiling method, the study of node importance and position in social graphs and engagement and influence measures. Finally the step of user community detection and evaluation is accomplished. For this last challenge, we introduce thematic cohesion scores, completing the topological, graph-based measures for group quality. This system is then applied on two corpora, extracted from two different online social media. The first is constituted of messages published on Twitter, gathering every activity performed by a set of 5,000 accounts on a long period. The second stems from a ToR-based social network, named Galaxy2, and includes every public action performed on the platform during its uptime. We evaluate the relevance of our system on these two datasets, showing the complementarity of user account characterisation tools (influence, behaviour and role), and user account communities (interaction strength, thematic cohesion), enriching the social graph exploitation with textual content elements

Étude des moyens de description et de manipulation des objets contenus dans des images binaires discrètes. Le calcul d'une ligne médiane, puis d'un graphe de la ligne médiane, aboutit a la représentation hiérarchisée de l'axe médian qui induit une analyse structurée de l'objet original. Différents procédés de manipulation de formes sont proposes et testés.

Les flux d’information suivent aujourd’hui des chemins complexes: la propagation des informations, impliquant éditeurs on-line, chaînes d’information en continu et réseaux sociaux, emprunte alors des chemins croisés, susceptibles d’agir sur le contenu et sa perception. Ce projet de thèse étudie l’adaptation des mesures de graphes classiques aux graphes multiplexes en relation avec le domaine étudié, propose de construire des visualisations à partir de plusieurs représentations graphiques des réseaux, et de les combiner (visualisations multi-vues synchronisées, représentations hybrides, etc.). L’accent est mis sur les modes d’interaction permettant de prendre en compte l’aspect multiplexe (multicouche) des réseaux. Ces représentations et manipulations interactives s’appuient aussi sur le calcul d’indicateurs propres aux réseaux multiplexes. Ce travail est basé sur deux jeux de données principaux: l’un est une archive de 12 ans de l’émission japonaise publique quotidienne NHK News 7, de 2001 à 2013. L’autre recense les participants aux émissions de télévision/radio françaises entre 2010 et 2015. Deux systèmes de visualisation s’appuyant sur une interface Web ont été développés pour analyser des réseaux multiplexes, que nous appelons «Visual Cloud» et «Laputa». Dans le Visual Cloud, nous définissons formellement une notion de similitude entre les concepts et les groupes de concepts que nous nommons possibilité de co-occurrence (CP). Conformément à cette définition, nous proposons un algorithme de classification hiérarchique. Nous regroupons les couches dans le réseau multiplexe de documents, et intégrons cette hiérarchie dans un nuage de mots interactif. Nous améliorons les algorithmes traditionnels de disposition de mise en forme de nuages de mots de sorte à préserver les contraintes sur la hiérarchie de concepts. Le système Laputa est destiné à l’analyse complexe de réseaux temporels denses et multidimensionnels. Pour ce faire, il associe un graphe à une segmentation. La segmentation par communauté, par attribut, ou encore par tranche temporelle, forme des vues de ce graphe. Afin d’associer ces vues avec le tout global, nous utilisons des diagrammes de Sankey pour révéler l’évolution des communautés (diagrammes que nous avons augmentés avec un zoom sémantique). Cette thèse nous permet ainsi de parcourir trois aspects (3V) des plus intéressants de la donnée et du BigData appliqués aux archives multimédia: Le Volume de nos données dans l’immensité des archives, nous atteignons des ordres de grandeurs qui ne sont pas praticables pour la visualisation et l’exploitation des liens. La Vélocité à cause de la nature temporelle de nos données (par définition). La Variété qui est un corollaire de la richesse des données multimédia et de tout ce que l’on peut souhaiter vouloir y investiguer. Ce que l’on peut retenir de cette thèse c’est que la traduction de ces trois défis a pris dans tous les cas une réponse sous la forme d’une analyse de réseaux multiplexes. Nous retrouvons toujours ces structures au coeur de notre travail, que ce soit de manière plus discrète dans les critères pour filtrer les arêtes par l’algorithme Simmelian backbone, que ce soit par la superposition de tranches temporelles, ou bien que ce soit beaucoup plus directement dans la combinaison d’indices sémantiques visuels et textuels pour laquelle nous extrayons les hiérarchies permettant notre visualisation
Nowadays, information follows complex paths: information propagation involving on-line editors, 24-hour news providers and social medias following entangled paths acting on information content and perception. This thesis studies the adaptation of classical graph measurements to multiplex graphs, to build visualizations from several graphical representations of the networks, and to combine them (synchronized multi-view visualizations, hybrid representations, etc.). Emphasis is placed on the modes of interaction allowing to take in hand the multiplex nature (multilayer) of the networks. These representations and interactive manipulations are also based on the calculation of indicators specific to multiplex networks. The work is based on two main datasets: one is a 12-year archive of the Japanese public daily broadcast NHK News 7, from 2001 to 2013. Another lists the participants in the French TV/radio shows between 2010 and 2015. Two visualization systems based on a Web interface have been developed for multiplex network analysis, which we call "Visual Cloud" and "Laputa". In the Visual Cloud, we formally define a notion of similarity between concepts and groups of concepts that we call co-occurrence possibility (CP). According to this definition, we propose a hierarchical classification algorithm. We aggregate the layers in a multiplex network of documents, and integrate that hierarchy into an interactive word cloud. Here we improve the traditional word cloud layout algorithms so as to preserve the constraints on the concept hierarchy. The Laputa system is intended for the complex analysis of dense and multidimensional temporal networks. To do this, it associates a graph with a segmentation. The segmentation by communities, by attributes, or by time slices, forms views of this graph. In order to associate these views with the global whole, we use Sankey diagrams to reveal the evolution of the communities (diagrams that we have increased with a semantic zoom). This thesis allows us to browse three aspects of the most interesting aspects of the data miming and BigData applied to multimedia archives: The Volume since our archives are immense and reach orders of magnitude that are usually not practicable for the visualization; Velocity, because of the temporal nature of our data (by definition). The Variety that is a corollary of the richness of multimedia data and of all that one may wish to want to investigate. What we can retain from this thesis is that we met each of these three challenges by taking an answer in the form of a multiplex network analysis. These structures are always at the heart of our work, whether in the criteria for filtering edges using the Simmelian backbone algorithm, or in the superposition of time slices in the complex networks, or much more directly in the combinations of visual and textual semantic indices for which we extract hierarchies allowing our visualization

Une partie des résultats de cette thèse sont initialement motivés par l'élaboration de schémas d'étiquetage permettant de réponde à l'adjacence, à la distance ou au routage. Ce document traite cependant de problèmes d'intérêt plus généraux tels que l'étude de bornes sur la densité de graphes, de la VC-dimension de familles d'ensembles, ou de propriétés métriques et structurelles.Nous établissons dans un premier temps des bornes supérieures sur la densité des sous-graphes de produits cartésien de graphes, puis des sous-graphes de demi-cubes. Pour ce faire, nous définissons des extensions du paramètre classique de VC-dimension. De ces bornes sur la densité, nous déduisons des bornes supérieures sur la longueur des étiquettes attribuées par un schéma d'adjacence à ces deux familles de graphes.Dans un second temps, nous nous intéressons à des schémas de distance et de routage pour deux familles importantes de la théorie métrique des graphes: les graphes médians et les graphes pontés. Nous montrons que la famille des graphes médians, sans cube, avec n sommets, admet des schémas de distance et de routage utilisant des étiquettes de O(\log^3 n). Ces étiquettes sont décodées en temps constant pour calculer, respectivement, la distance exacte entre deux sommets, ou le port vers un sommet rapprochant une source d'une destination. Nous décrivons ensuite un schéma de distances 4-approchées pour la famille des graphes pontés, sans K_4, avec n sommets, utilisant des étiquettes de O(\log^3 n) bits. Ces dernières peuvent être décodées en temps constant pour obtenir une valeur entre la distance exacte et quatre fois celle-ci
Constructing labeling schemes supporting adjacency, distance or routing queries constituted the initial motivation of most of the results of this document. However, this manuscript concerns problem of more general interest such as bounding the density of graphs, studying the VC-dimension of set families, or investigating on metric and structural properties of graphs. As a first contribution, we upper bound the density of the subgraphs of Cartesian products of graphs, and of the subgraphs of halved-cubes. To do so, we extend the classical notion of VC-dimension (already used in 1994 by Haussler, Littlestone, and Warmuth to upper bound the density of the subgraphs of hypercubes). From our results, we deduce upper bounds on the size of labels used by an adjacency labeling scheme on these graph classes. We then investigate on distance and routing labeling schemes for two important families of metric graph theory: median graphs and bridged graphs. We first show that the class of cube-free median graphs on n vertices enjoys distance and routing labeling schemes both using labels of O(\log^3 n) bits. These labels can be decoded in constant time to respectively return the exact distance between two vertices, or a port to take from a source vertex in order to get (strictly) closer to a target one. We then describe an approximate distance labeling scheme for the family of K_4-free bridged graphs on n vertices. This scheme also uses labels of size O(\log^3 n) that can be decoded in constant time to return a value of at most four time the exact distance between two vertices

Les graphes sont des objets mathématiques abstraits utilisés pour modéliser les interactions entre les éléments constitutifs des systèmes complexes. Cette utilisation est motivée par le fait qu’il existe un lien fondamental entre la structure de ces interactions et les propriétés macroscopiques de ces systèmes. La théorie de la percolation offre un paradigme de choix pour analyser la structure de ces graphes, et ainsi mieux comprendre les conditions dans lesquelles ces propriétés émergent. Les interactions dans une grande variété de systèmes complexes partagent plusieurs propriétés structurelles universelles, et leur incorporation dans un cadre théorique unique demeure l’un des principaux défis de l’étude des systèmes complexes. Exploitant une approche multitype, une idée toute simple mais étonnamment puissante, nous avons unifié l’ensemble des modèles de percolation sur graphes aléatoires connus en un même cadre théorique, ce qui en fait le plus général et le plus réaliste proposé à ce jour. Bien plus qu’une simple compilation, le formalisme que nous proposons augmente significativement la complexité des structures pouvant être reproduites et, de ce fait, ouvre la voie à plusieurs nouvelles avenues de recherche. Nous illustrons cette assertion notamment en utilisant notre modèle pour valider et formaliser certaines intuitions inspirées de résultats empiriques. Dans un premier temps, nous étudions comment la structure en réseau de certains systèmes complexes (ex. réseau de distribution électrique, réseau social) facilite leur surveillance, et par conséquent leur éventuel contrôle. Dans un second temps, nous explorons la possibilité d’utiliser la décomposition en couches “k-core” en tant que structure effective des graphes extraits des systèmes complexes réels. Enfin, nous utilisons notre modèle pour identifier les conditions pour lesquelles une nouvelle stratégie d’immunisation contre des maladies infectieuses est la stratégie optimale.
Graphs are abstract mathematical objects used to model the interactions between the elements of complex systems. Their use is motivated by the fact that there exists a fundamental relationship between the structure of these interactions and the macroscopic properties of these systems. The structure of these graphs is analyzed within the paradigm of percolation theory whose tools and concepts contribute to a better understanding of the conditions for which these emergent properties appear. The underlying interactions of a wide variety of complex systems share many universal structural properties, and including these properties in a unified theoretical framework is one of the main challenges of the science of complex systems. Capitalizing on a multitype approach, a simple yet powerful idea, we have unified the models of percolation on random graphs published to this day in a single framework, hence yielding the most general and realistic framework to date. More than a mere compilation, this framework significantly increases the structural complexity of the graphs that can now be mathematically handled, and, as such, opens the way to many new research opportunities. We illustrate this assertion by using our framework to validate hypotheses hinted at by empirical results. First, we investigate how the network structure of some complex systems (e.g., power grids, social networks) enhances our ability to monitor them, and ultimately to control them. Second, we test the hypothesis that the “k-core” decomposition can act as an effective structure of graphs extracted from real complex systems. Third, we use our framework to identify the conditions for which a new immunization strategy against infectious diseases is optimal.

L'objectif de cette thèse est d'étudier les conditions susceptibles d'expliquer la dominance économique de certaines activités dans l'industrie multimédia. La première partie concerne la dynamique industrielle du multimédia. Elle interprète l'émergence de l'industrie comme le résultat d'un processus de convergence des technologies, aboutissant finalement à la convergence des activités elles-mêmes. La seconde partie met en évidence les conséquences de ces mutations industrielles sur la transformation de l'environnement concurrentiel et sur le comportement stratégique des firmes. Enfin, la troisième partie vise à spécifier empiriquement le type d'organisation structurale auquel répond l'industrie multimédia. A partir d'une étude systématique des relations intersectorielles sur la période 2000-2001, notre analyse structurale permet à la fois de confirmer le phénomène de convergence des activités, et de souligner leur interdépendance dans le processus de structuration de l'industrie.

Soit D un digraphe simple (sans cycle orienté de longueur 2 ). En 1990, P. Seymour a conjecturé que D a un sommet v avec un second voisinage extérieur au moins aussi grand que son (premier) voisinage extérieur [1]. Cette conjecture est connue sous le nom de la conjecture du second voisinage du Seymour (SNC). Cette conjecture, si elle est vraie, impliquerait, un cas spécial plus faible (mais important) de la conjecture de Caccetta et Häggkvist [2] proposé en 1978 : tout digraphe D avec un degré extérieur minimum au moins égale à jV (D)j=k a un cycle orienté de longueur au plus k. Le cas particulier est k = 3, et le cas faible exige les deux : le degré extérieur minimum et le degré intérieur minimum de D sont au moins égaux à jV (D)j=k. La conjecture de Seymour restreinte au tournoi est connue sous le nom de conjecture de Dean [1]. En 1996, Fisher [3] a prouvé la conjecture de Dean en utilisant un argument de probabilité. En 2003, Chen, Shen et Yuster [4] ont démontré que tout digraphe a un sommet v tel que d+(v) _ d++(v) où =0.657298..... est l'unique racine de l'équation 2x3 + x2 - 1 = 0. En 2000, Havet et Thomassé [5] ont donné une preuve combinatoire de la conjecture de Dean, en utilisant un outil appelé l'ordre médian. Ils ont démontré que le dernier sommet d'un tel ordre a toujours un second voisinage extérieur au moins aussi grand que son voisinage extérieur. En 2007, Fidler et Yuster [6] ont utilisé l'ordre médian et un autre outil qui s'appelle le digraphe de dépendance afin de prouver la conjecture de Seymour pour tout digraphe D ayant un degré minimum jV (D)j 2. Ils l'ont montré pour tout tournoi où manque un autre sous-tournoi. El Sahili a conjecturé que pour tout D, il existe un completion T de D et un ordre médian de T tel que le denier sommet a un second voisinage extérieur au moins aussi grand que son voisinage extérieur (EC). Il est clair que, EC implique SNC. Cependant, EC propose une méthode afin de résoudre la SNC. En général, on oriente les non arcs de D de manière appropriée, afin d'obtenir un tournoi T et on essaie de trouver un sommet particulier (le denier sommet d'un ordre médian) avec la propriété désirée. Clairement, grâce aux résultats de [5] et [6], la EC est valable pour tournoi, et tout tournoi où manque un autre sous-tournoi. Nous allons vérifier EC pour tout digraphe D ayant un degré minimum jV (D)j 2. Alors, EC est vraie pour tout digraphe où la SNC est déjà connue d'être vraie non trivialement. Nous sommes aussi intéressés à la version pondérée de SNC et EC. En réalité, Fidler et Yuster [6] ont utilisé les digraphes de dépendance comme un outil supplémentaire et le fait que la SNC pondérée est vraie pour les tournois afin de prouver la SNC pour tout digraphe D ayant un degré minimum1 jV (D)j 2. Nous allons définir le digraphe de dépendance de façon plus générale et qui convient à n'importe quel digraphe. Nous allons utiliser le digraphe de dépendance et l'ordre médian comme des outils dans nos contributions à cette conjecture. Suivant la méthode proposée par la EC, nous démontrons la version pondérée de EC, et par conséquent la SNC, pour les classes des digraphes suivants : Digraphes où manque une étoile généralisée, soleil, étoile, ou un graphe complété. En outre, nous prouvons la EC, et par conséquent la SNC, pour digraphes où manque un peigne et digraphe où manque un graphe complet moins 2 arêtes indépendantes ou moins les arêtes d'une cycle de longueur 5. Par ailleurs, nous prouvons la EC, et par conséquent la SNC, pour les digraphes où manque n étoiles disjointes, sous certaines conditions sur les deux degrés minimum du digraphe de dépendance. Des conditions plus faible sont exigées dans le cas n = 1; 2; 3. Dans certains cas, on trouve au moins deux sommets avec la propriété désirée.

Mestrado em Gestão de Sistemas de Informação
Atualmente, as redes de distribuição de energia vivem uma grande mudança de paradigma, assente no desenvolvimento sustentável, no aparecimento de novas unidades de produção renováveis e na mudança de redes passivas tradicionais para redes ativas. Esta complexidade e incremento vai original um maior desafio na sua gestão, monotorização e eficiência. Por essa razão, é necessário encontrar novas ferramentas que permitam ajudar no estudo e análise das redes de distribuição. Neste contexto, o projeto realizado aborda a construção e o desenvolvimento de um modelo de dados que simule a topologia da rede de distribuição elétrica de alta e média tensão no formato de um grafo (i.e., conjunto de nós e arestas), e que posteriormente possa ser utilizado como uma camada de construção e suporte para a elaboração de use cases de analítica. De forma a atingir este objetivo, foi elaborado um modelo conceptual, três versões distintas do grafo e um conjunto de use cases de analítica relevantes para a visualização, estudo e análise da rede de distribuição. A construção do grafo e o desenvolvimento dos use cases analíticos teve por base informação proveniente de um operador de rede de distribuição (ORD).
Nowadays, energy distribution networks are undergoing a major paradigm shift, based on sustainable development, emergence of new renewable production units and shift from traditional passive networks to active networks. This complexity and increase will create a greater challenge in its management, monitoring and efficiency. For this reason, it is necessary to find new tools that can help in the study and analysis of distribution networks.In this context, the aim of this project is to construct and develop a data model that simulates the topological structure of high and medium voltage electrical distribution grid in the form of a graph (i.e., a set of nodes and edges) and use it as a construction and support layer for the elaboration of analytical use cases. In order to achieve this objective, a conceptual model, three different versions of the graph and a set of analytical use cases relevant to the visualization, study and analysis of the distribution grid was developed. The construction of the graph and the development of the analytical use cases is based on information provided by a Distribution System Operator (DSO).
info:eu-repo/semantics/publishedVersion

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
We study two types of Neumann problem related to Capillary problem and to the evolution of graphs under mean curvature flow in Riemannian manifolds endowed with a Killing vector field. In particular, we prove the existence of Killing graphs with prescribed mean curvature and prescribed boundary conditions.
Estudamos dois tipos de problemas relacionados com a Neumann problema capilar e à evolução dos gráficos sob fluxo de curvatura média em variedades Riemannianas dotados com um campo de vetores Killing. Em particular, provamos a existência de Matar gráficos prescrito com curvatura média e condições de contorno prescritas.

Neste trabalho mostramos que dado um domínio exterior de classe C0 contido em uma superfície umb lica de H3; com curvatura média constante H 2 [0; 1); existe uma família de gracos de Killing com curvatura média constante H: O bordo de cada um destes gracos está contido nesta superfície umbílica e a norma do gradiente da função no bordo pode ser prescrita por um certo valor s 0.
In this paper we show that given an exterior domain of class C0 contained in an umbilical surface of H3; with constant mean curvature H 2 [0; 1); there exists a family of Killing graphs with constant mean curvature H: The boundary of each of these graphs is contained in this umbilical surface and the norm of the gradient of the function in the boundary can be prescribed by a certain value s 0:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
We study problems of existence and uniqueness of constant mean curvature surfaces with prescribed boundary satisfying the bounded slope condition. The surfaces are given as Euclidean graphs in R3 and as parabolic graphs in H3, over bounded domains contained in totally geodesic surfaces in these ambients, or moreover, as radial graphs over bounded domains contained in S2.
Estudamos problemas de existência e unicidade de superfícies de curvatura média constante com bordo prescrito satisfazendo a condição de declividade limitada (CDL). Tais superfícies são dadas como gráficos euclidianos (verticais) em R3 e como gráficos parabólicos em H3, definidos sobre domínios limitados contidos em superfícies totalmente geodésicas destes ambientes, ou ainda como gráficos radiais em R3 sobre domínios limitados contidos em S2.

Orientador: Alexandre Xavier Falcão
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: Segmentação de imagens médicas é crucial para extrair medidas de objetos 3D (estruturas anatômicas) que são úteis no diagnóstico e tratamento de doenças. Nestas aplicações, segmentação interativa é necessária quando métodos automáticos falham ou não são factíveis. Métodos por corte em grafo são considerados o estado da arte em segmentação interativa, mas diversas abordagens utilizam o algoritmo min-cut/max-flow, que é limitado à segmentação binária, sendo que segmentação de múltiplos objetos pode economizar tempo e esforço do usuário. Este trabalho revisita a transformada imagem floresta diferencial (DIFT, em inglês) -- uma abordagem por corte em grafo adequada para segmentação de múltiplos objetos -- resolvendo problemas relacionados a ela. O algoritmo da DIFT executa em tempo proporcional ao número de voxels nas regiões modificadas em cada execução da segmentação (sublinear). Tal característica é altamente desejável em segmentação interativa de imagens 3D para responder as ações do usuário em tempo real. O algoritmo da DIFT funciona da seguinte forma: o usuário desenha marcadores (traço com voxels de semente) rotulados dentro de cada objeto e o fundo, enquanto o computador interpreta a imagem como um grafo, cujos nós são os voxels e os arcos são definidos por pixels vizinhos, produzindo como resultado uma floresta de caminhos ótimos (partição na imagem) enraizada nos nós sementes do grafo. Nesta floresta, cada objeto é representado pela floresta de caminhos ótimos enraizado em suas sementes internas. Tais árvores são pintadas com a mesmo cor associada ao rótulo do marcador correspondente. Ao adicionar ou remover marcadores, é possível corrigir a segmentação até o mapa de rótulo de objeto representar o resultado desejado. Para garantir consistência na segmentação, métodos baseados em semente sempre devem manter a conectividade entre os voxels e suas sementes. Entretanto, isto não é mantido em algumas abordagens, como Random Walkers ou quando o mapa de rótulos é filtrado para suavizar a fronteira dos objetos. Esta conectividade é primordial para realizar correções sem recomeçar o processo depois de cada intervenção do usuário. Todavia, foi observado que a DIFT falha em manter consistência da segmentação em alguns casos. Consertamos este problema tanto no algoritmo da DIFT, quanto após a suavização dos objetos. Estes resultados comparam diversas estruturas anatômicas 3D de imagens de ressonância magnética e tomografia computadorizada
Abstract: Medical image segmentation is crucial to extract measures from 3D objects (body anatomical structures) that are useful for diagnosis and treatment of diseases. In such applications, interactive segmentation is necessary whenever automated methods fail or are not feasible. Graph-cut methods are considered the state of the art in interactive segmentation, but most approaches rely on the min-cut/max-flow algorithm, which is limited to binary segmentation while multi-object segmentation can considerably save user time and effort. This work revisits the differential image foresting transform (DIFT) ¿ a graph-cut approach suitable for multi-object segmentation in linear time ¿ and solves several problems related to it. Indeed, the DIFT algorithm can take time proportional to the number of voxels in the regions modified at each segmentation execution (sublinear time). Such a characteristic is highly desirable in 3D interactive segmentation to respond the user's actions as close as possible to real time. Segmentation using the DIFT works as follows: the user draws labeled markers (strokes of connected seed voxels) inside each object and background, while the computer interprets the image as a graph, whose nodes are the voxels and arcs are defined by neighboring voxels, and outputs an optimum-path forest (image partition) rooted at the seed nodes in the graph. In the forest, each object is represented by the optimum-path trees rooted at its internal seeds. Such trees are painted with same color associated to the label of the corresponding marker. By adding/removing markers, the user can correct segmentation until the forest (its object label map) represents the desired result. For the sake of consistency in segmentation, similar seed-based methods should always maintain the connectivity between voxels and seeds that have labeled them. However, this does not hold in some approaches, such as random walkers, or when the segmentation is filtered to smooth object boundaries. That connectivity is also paramount to make corrections without starting over the process at each user intervention. However, we observed that the DIFT algorithm fails in maintaining segmentation consistency in some cases. We have fixed this problem in the DIFT algorithm and when the obtained object boundaries are smoothed. These results are presented and evaluated on several 3D body anatomical structures from MR and CT images
Mestrado
Ciência da Computação
Mestre em Ciência da Computação

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The purpose of this study was to investigate the introduction of arithmetic mean concept based on the use of graphic representations, and with the assistance of computational environement by using the software Tabletop. To reach this purpose, a nearly experimental study has been accomplished with two groups of students, the experimental group GE and the control group GC both fourth graders of a Sao Paulo public school. The research was divided into three phases, namely: Pre-Test, Teaching Interference (experimental factor) and Post-Test. The activities composing the Teaching Interference have been adjusted to the Conceptual Fields Theory proposed by Vergnaud. To develop these activities we based on graphics understanding levels proposed by Curcio and on arithmetic mean properties proposed by Straus & Bichler. The GE has taken part in the three phases of the study seeing that the teaching interference activities, developed within computacional environment, aimed at both, the introduction of arithmetic mean concept and the graphics reading and interpretation development. The GC has also taken part in tests application, but it was left out the experimental factor. The study has intended to answer the following question: Which teaching interference contributions are proposed for the introduction of arithmetic mean concept into fourth graders , by making use of computational environment? To answer this research question, we based ourselves on qualified and quantified analysis of the results obtained from the tests in both groups and on the answers given by GE students to the activities cards of the intervention. By comparing the intergroups post-test results, one verify that the GE students have presented a better performance than the GC one s, specially regarding arithmetic mean concept. On the other hand, the analisys of the results within the groups pointed to an improvement in the post-test performed by the Experimental Group in respect to the pre-test, regarding the reading and interpretation of bar graphics, as well as in arithmetic mean concept. These data permit us to conclude that the introduction to arithmetic mean concept based on graphic representation has been favoured by the use of Tabletop software, since it allows the students to catch the proprieties and relations envolved in Conceptual Field formed by graphic reading and interpretation as well as arithmetic mean
O objetivo do estudo foi investigar a introdução do conceito de média aritmética com base no uso das representações gráficas e com o auxílio do ambiente computacional, dentro do qual foi empregado o software Tabletop. Para se atingir este objetivo, foi feito um estudo quase-experimental com dois grupos de alunos: o grupo experimental GE - e o grupo de controle GC - ambos da 4ª série Ensino Fundamental de uma escola da rede pública estadual da cidade de São Paulo. A pesquisa dividiu-se em três fases, a saber: Pré-teste, Intervenção de Ensino (fator experimental) e Pós-teste. As atividades constituintes da Intervenção de Ensino ajustaram-se à Teoria dos Campos Conceituais proposta por Vergnaud. Para elaboração das atividades tomou-se como base os níveis de compreensão de gráficos propostos por Curcio e as propriedades de média aritmética propostas por Strauss e Bichler. O GE participou das três fases do estudo, sendo as atividades de intervenção de ensino desenvolvidas em ambiente computacional, visando à introdução do conceito de média aritmética e o desenvolvimento da leitura e interpretação de gráficos. O GC também participou da aplicação dos testes, porém permaneceu isento da aplicação do fator experimental. O estudo propôs-se a responder à seguinte questão: Quais as contribuições da intervenção de ensino proposta para a introdução do conceito de média aritmética em alunos da 4ª série do Ensino Fundamental, com o uso do ambiente computacional? Para responder a esta questão de pesquisa, tomamos por base as análises quantitativa e qualitativa dos resultados obtidos nos testes em ambos os grupos e as respostas dadas pelos alunos do GE às fichas de atividades da intervenção. Na comparação intergrupos dos resultados do pós-teste, constatou-se que os alunos do GE mostraram um desempenho superior aos do GC, sobretudo, quanto ao conceito de média aritmética. Já a análise dos resultados intragrupos apontou uma melhora no desempenho dos alunos do GE no pós-teste em relação ao pré-teste, no que se refere à leitura e interpretação do gráfico de barras, assim como no conceito de média aritmética. Estes dados permitem concluir que a introdução ao conceito de média aritmética baseada na representação gráfica foi favorecida pelo emprego do software Tabletop, visto que este possibilitou ao aluno a descoberta de propriedades e relações envolvidas no Campo Conceitual constituído pela leitura e interpretação de gráficos e média aritmética

Simuladores cirúrgicos possibilitam a médicos e estudantes a visualização de órgãos humanos representados com alto grau de realismo. Trata-se de um grande avanço que reduz o tempo e os custos na formação desses profissionais, oferecendo menor risco aos pacientes. Entretanto, esses sistemas comerciais de simuladores têm, em geral, suas representações voltadas apenas para a superfície dos órgãos. Assim, quando ocorre o corte de um órgão com estruturas internas, o seu interior aparece vazio, não mostrando, por exemplo, estruturas anatômicas como vasos sanguíneos no seu interior. Trabalhos na área de textura sólida também não lidam com objetos que possuem estruturas internas modeladas geometricamente. Nessa dissertação é proposto um sistema gráfico interativo que permite cortes arbitrários em estruturas anatômicas, reconstruindo a textura nas superfícies da zona de corte de forma a respeitar as estruturas internas. O sistema protótipo desenvolvido propõe que cortes definidos pelo usuário alterem modelos tridimensionais, retriangulando apropriadamente a malha nas regiões de corte. Como estudo de caso, foi selecionado um modelo de fígado humano com vasos, apresentando como resultado a visualização interna em tempo real desse objeto para quaisquer planos. Essa abordagem pode ser considerada como um passo para os simuladores se tornarem ainda mais realistas. Extensões do trabalho envolvem a integração com simuladores médicos existentes, bem como uma validação do sistema por parte dos profissionais da Medicina.
Surgical simulators help doctors and students the visualization of human organs with high realism. Simulators are an improvement which reduce time and cost spend by professionals, offering less risk to the patients. Besides, studies show that the amount of realism seen in the simulators is related to the engaging of students in learning. However, these commercial simulator systems represent only the surface of organs. Thus, when a cut of an organ with internal structures occurs, its interior remains empty, without showing anatomical structures such as blood vessels inside. Research in the area of solid texture typically do not deal with objects which have internal structures geometrically modeled. In this dissertation, we propose a graphical interactive system that allows arbitrary cuts in anatomical structures, reconstructing the texture in the cutting zone’s surface according to its internal structures. With the developed application, cuts defined by the user transform three-dimensional models, triangulating properly the mesh in the cutting area. As a case study we selected a human liver model with vessels, presenting as result the internal visualization of the object in real time for any cut planes. We consider this approach as a step in order for simulators to become more realistic. Extensions of the work include the integration with current medical simulators, as well as a validation of the system by the Medicine professionals.

S’inscrivant dans un contexte de veille et d’intelligence d’entreprise sur Internet, l’objectif de cette thèse est d’élaborer des outils et des méthodes permettant d’identifier, analyser, modéliser et représenter le cheminement des buzz sur Internet. Tout buzz a un ou plusieurs points d’origine : les sources primaires. L’information est ensuite relayée par des sources secondaires qui vont accélérer ou non la propagation en fonction de leur degré d’influence. Tout au long du cycle de vie du buzz, le contenu sémantique est amené à évoluer. La compréhension d’un buzz sur Internet passe ainsi par l’analyse de ce qui se dit et la qualification des émetteurs. Nos travaux s’axeront donc autour de deux types d’analyses complémentaires : une analyse topologique des sources (théorie des graphes et des réseaux) et une analyse du contenu textuel (linguistique de corpus)
This thesis is in the context of strategic and competitive intelligence. Its goal is to develop tools and methods to identify, analyze, model and represent how buzz spread on the Internet. Any buzz has one or more starting point(s), i.e. primary source(s). The information is then passed on by secondary sources which may speed or slow down its spreading depending on their influence. Throughout the buzz lifecycle, the semantic content can evolve. To understand a buzz on the Internet, one needs to analyze what is said and qualify who speaks. This thesis will focus on two main points : a topological analysis of the sources (graph theory and networks), and an analysis of the textual content (corpus linguistics)

Cirurgias minimamente invasivas correspondem a uma importante especialidade da Medicina, cuja aplicação em larga escala depende do treinamento de novos cirurgiões em habilidades específicas que podem ser aprimoradas através do uso de simuladores virtuais de cirurgia. Entretanto, tais aplicações demandam alta qualidade visual das simulações de órgãos internos, que idealmente podem ser realizadas com base em aproximações de mais alta ordem da interação luz-matéria. Trabalhos recentes têm proposto abordagens híbridas onde dados da BRDF (Bidirectional Reflectance Distribution Function - Função de Distribuição de Reflectância Bidirecional) de órgãos vivos têm sido amostrados ou estimados, para orientar técnicas de rendering em tempo real. O presente trabalho propõe um pipeline para o rendering de estruturas orgânicas baseado em Física visando a simulação de cirurgia compatível com alto nível de aproximação da interação luz-matéria. Através de um novo método de amostragem da BRDF de órgãos vivos por meio de laparoscopias convencionais, e do estudo de formas de representação para os dados amostrados, imagens de órgãos humanos são geradas em sistemas de rendering de tempo real e sistemas baseados em algoritmos de iluminação global. A metodologia proposta foi aplicada em um experimento realizado através de uma Colecistectomia, cujos importantes resultados caracterizam-se pela cobertura de aproximadamente 22% da BRDF de um fígado humano vivo, configurando assim uma contribuição singular para técnicas de amostram de BRDF de órgãos e rendering de órgãos baseado em Física.
Minimally invasive surgeries are an important specialty of Medicine. Virtual simulators allow the development of the needed skills for new surgeons. Such simulators demand high visual quality of the internal organs that ideally can be performed based on higher-order approximations of the light-material interaction. Recent work proposes hybrid approaches where the BRDF (Bidirectional Reflectance Distribution Function) data for living organs was sampling or estimated to guide real-time rendering techniques. This work proposes a pipeline for physically-based rendering of organic structures with the goal of surgery simulations with a high level of approximation for the light-material interaction. We present a new sampling method for measuring BRDFs for living organs based on conventional laparoscopy. With this data we are able to render human organs in real-time and also improve global illumination results. The methodology was applied in an experiment performed through a Cholecystectomy. Our results achieved a high BRDF coverage of 22% for a living human liver, establishing a singular contribution for the sampling of BRDF in-vivo organs and physically-based rendering.

Depuis 2004, les médias sociaux en ligne ont connu une croissance considérable. Ce développement rapide a eu des effets intéressants pour augmenter la connexionet l'échange d'informations entre les utilisateurs, mais certains effets négatifs sont également apparus, dont le nombre de faux comptes grandissant jour après jour.Les sockpuppets sont les multiples faux comptes créés par un même utilisateur. Ils sont à l'origine de plusieurs types de manipulations comme la création de faux comptes pour louer, défendre ou soutenir une personne ou une organisation, ou pour manipuler l'opinion publique. Dans cette thèse, nous présentons SocksCatch, un processus complet de détection et de groupage des sockpuppets composé de trois phases principales : la première phase a pour objectif la préparation du processus et le pré-traitement des données; la seconde phase a pour objectif la détection des comptes sockpuppets à l'aide d'algorithmes d'apprentissage automatique; la troisième phase a pour objectif le regroupement des comptes sockpuppets créés par un même utilisateur à l'aide d'algorithmes de détection de communautés. Ces phases sont déclinées en trois étapes : une étape "modèle" pour représenter les médias sociaux en ligne, où nous proposons un modèle général de médias sociaux dédié à la détection et au regroupement des sockpuppets ; une étape d'adaptation pour ajuster le processus à un média social spécifique, où nous instancions et évaluons le modèle SocksCatch sur un média social sélectionné ; et une étape en temps réel pour détecter et grouper les sockpuppets en ligne, où SocksCatch est déployé en ligne sur un média social sélectionné. Des expérimentations ont été réalisées sur l'étape d'adaptation en utilisant des données réelles extraites de Wikipédia anglais. Afin de trouver le meilleur algorithme d'apprentissage automatique pour la phase de détection de sockpuppet, les résultats de six algorithmes d'apprentissage automatique sont comparés. En outre, ils sont comparés à la littérature où les résultats de la comparaison montrent que notre proposition améliore la précision de la détection des sockpuppets. De plus, les résultats de cinq algorithmes de détection de communauté sont comparés pour la phase de regroupement de Sockpuppet, afin de trouver le meilleur algorithme de détection de communauté qui sera utilisé en temps réel
Since 2004, online social medias have grown hugely. This fast development had interesting effects to increase the connection and information exchange between users, but some negative effects also appeared, including fake accounts number growing day after day. Sockpuppets are multiple fake accounts created by a same user. They are the source of several types of manipulation such as those created to praise, defend or support a person or an organization, or to manipulate public opinion. In this thesis, we present SocksCatch, a complete process to detect and group sockpuppets, which is composed of three main phases: the first phase objective is the process preparation and data pre-processing; the second phase objective is the detection of the sockpuppet accounts using machine learning algorithms; the third phase objective is the grouping of sockpuppet accounts created by a same user using community detection algorithms. These phases are declined in three stages: a model stage to represent online social medias, where we propose a general model of social media dedicated to the detection and grouping of sockpuppets; an adaptation stage to adjust the process to a particular social media, where we instantiate and evaluate the SocksCatch model on a selected social media; and a real-time stage to detect and group the sockpuppets online, where SocksCatch is deployed online on a selected social media. Experiments have been performed on the adaptation stage using real data crawled from English Wikipedia. In order to find the best machine learning algorithm for sockpuppet's detection phase, the results of six machine learning algorithms are compared. In addition, they are compared with the literature, and the results show that our proposition improves the accuracy of the detection of sockpuppets. Furthermore, the results of five community detection algorithms are compared for sockpuppet's grouping phase, in order to find the best community detecton algorithm that will be used in real-time stage

A histopatologia é considerada um dos recursos diagnósticos mais importantes na prática médica e caracteriza-se pelo estudo das alterações estruturais e morfológicas das células e dos tecidos causadas por doenças. Atualmente, o principal método utilizado no diagnóstico histopatológico de imagens microscópicas, obtidas por meio de amostras em exames convencionais, é a avaliação visual do patologista, a qual se baseia na experiência do mesmo. O uso de técnicas de processamento computacional de imagens possibilita a identificação de elementos estruturais e a determinação de características inerentes, subsidiando o estudo da organização estrutural das células e de suas variações patológicas. A utilização de métodos computacionais no auxílio ao diagnóstico visa diminuir a subjetividade do processo de avaliação e classificação realizado pelo médico. Diferentes características dos tecidos podem ser mapeadas por meio de métricas específicas que poderão ser utilizadas em sistemas de reconhecimento de padrões. Dentro desta perspectiva, o objetivo geral deste trabalho inclui a proposta, a implementação e a avaliação de um método para a identificação e a análise de estruturas histológicas, a ser utilizado para a análise de lesões neoplásicas do colo do útero (NICs) a partir de amostras histopatológicas. Este trabalho foi desenvolvido em colaboração com uma equipe de patologistas, especialistas do domínio. As imagens microscópicas digitalizadas foram adquiridas a partir de lâminas previamente fixadas, contendo amostras de biópsias. Para segmentação dos núcleos celulares, foi implementado um pipeline de operadores morfológicos. Métodos de segmentação baseados em cor também foram testados e comparados à abordagem morfológica. Foi proposta e implementada uma abordagem baseada em camadas para representação do tecido, adotando-se a Triangulação de Delaunay (TD) como modelo de grafo de vizinhança. A TD apresenta algumas propriedades particulares que permitem a extração de métricas específicas. Foram utilizados algoritmos de agrupamento e morfologia de grafos, adotando-se critérios de semelhança e relações de adjacência entre os triângulos da rede, a fim de se obter a fronteira entre as camadas histológicas do tecido epitelial de forma automática. As seguintes métricas foram extraídas dos agrupamentos resultantes: grau médio, entropia e taxa de ocupação dos triângulos da rede. Finalmente, foi projetado um classificador estatístico levando-se em consideração os diferentes agrupamentos que poderiam ser obtidos a partir das imagens de treinamento. Valores de acurácia, sensitividade e especificidade foram utilizadas para avaliação dos resultados obtidos. Foi implementada validação cruzada em todos os experimentos realizados e foi utilizado um total de 116 imagens. Primeiro, foi avaliado a acurácia da metodologia proposta na determinação correta da presença de anomalia no tecido, para isto, todas as imagens que apresentavam NICs foram agrupadas em uma mesma classe. A maior taxa de acurácia obtida neste experimento foi de 88%. Em uma segunda etapa, foram realizadas avaliações entre as seguintes classes: Normal e NIC-I; NIC-I e NIC-II, e, NIC-II e NIC-III, obtendo-se taxas de acurácia máximas de 73%, 77% e 86%, respectivamente. Além disso, foi verificada também, a acurácia na discriminação entre os três tipos de NICs e regiões normais, obtendo-se acurácia de 64%. As taxas de ocupação relativas aos agrupamentos representativos das camadas basais e superficiais, foram os atributos que levaram às maiores taxas de acurácia. Os resultados obtidos permitem verificar a adequação do método proposto na representação e análise do processo de evolução das NICs no tecido epitelial do colo uterino.
Histopathology is considered one of the most important diagnostic tools in medical routine and is characterized by the study of structural and morphological changes of the cells in biological tissues caused by diseases. Currently, the visual assessment of the pathologist is the main method used in the histopathological diagnosis of microscopic images obtained from biopsy samples. This diagnosis is usually based on the experience of the pathologist. The use of computational techniques in the processing of these images allows the identification of structural elements and the determination of inherent characteristics, supporting the study of the structural organization of tissues and their pathological changes. Also, the use of computational methods to improve diagnosis aims to reduce the subjectivity of the evaluation made by the physician. Besides, different tissue characteristics can be mapped through specific metrics that can be used in pattern recognition systems. Within this perspective, the overall objective of this work includes the proposal, the implementation and the evaluation of a methodology for the identification and analysis of histological structures. This methodology includes the specification of a method for the analysis of cervical intraepithelial neoplasias (CINs) from histopathological samples. This work was developed in collaboration with a team of pathologists. Microscopic images were acquired from blades previously stained, containing samples of biopsy examinations. For the segmentation of cell nuclei, a pipeline of morphological operators were implemented. Segmentation techniques based on color were also tested and compared to the morphological approach. For the representation of the tissue architecture an approach based on the tissue layers was proposed and implemented adopting the Delaunay Triangulation (DT) as neighborhood graph. The DT has some special properties that allow the extraction of specific metrics. Clustering algorithms and graph morphology were used in order to automatically obtain the boundary between the histological layers of the epithelial tissue. For this purpose, similarity criteria and adjacency relations between the triangles of the network were explored. The following metrics were extracted from the resulting clusters: mean degree, entropy and the occupation rate of the clusters. Finally, a statistical classifier was designed taking into account the different combinations of clusters that could be obtained from the training process. Values of accuracy, sensitivity and specificity were used to evaluate the results. All the experiments were taken in a cross-validation process (5-fold) and a total of 116 images were used. First, it was evaluated the accuracy in determining the correct presence of abnormalities in the tissue. For this, all images presenting CINs were grouped in the same class. The highest accuracy rate obtained for this evaluation was 88%. In a second step, the discrimination between the following classes were analyzed: Normal/CIN 1; CIN 1/CIN 2, and, CIN 2/CIN 3, which represents the histological grading of the CINs. In a similar way, the highest accuracy rates obtained were 73%, 77% and 86%, respectively. In addition, it was also calculated the accuracy rate in discriminating between the four classes analyzed in this work: the three types of CINs and the normal region. In this last case, it was obtained a rate of 64%.The occupation rate for the basal and superficial layers were the attributes that led to the highest accuracy rates. The results obtained shows the adequacy of the proposed method in the representation and classification of the CINs evolution in the cervical epithelial tissue.

The diploma thesis analyzes modern social networks, with focus on Facebook network in Czech environment. It shows Facebook tools and its possible usage for marketing purposes. Facebook functionality is shown on practical examples, including own Facebook application. It contains suggestions for Facebook marketing strategy improvements.

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Neste trabalho, apresentamos um estudo das hipersuperfícies tipo-espaço imersas no ambiente −R × Hn, exibindo condições para que tais hipersuperfícies sejam slices {t0}×Hn. Para uma melhor compreensão das demonstrações e dos resultados, inserimos processos de diferenciação, cálculos de gradientes e Laplacianos que, juntamente com o princípio do máximo de Omori-Yau, foram cruciais no desenvolvimento dos resultados que, em sua maioria são do tipo Bernstein. Também incluímos um resultado do tipo Calabi.
In this work we present a study of the spacelike hypersurfaces immersed in the manifold −R × Hn providing sufficient conditions for such hypersurfaces be slices, {t0}×Hn. For a better understanding of the proofs and results, we have added differentiation processes, gradient computations and Laplacians which jointly with the Omori-Yau Maximum Principle were crucial in the developing of the results whose are mostly Bernstein-type. In the elapsing we also included Calabi-type results.

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Secretaria da Educação do Estado de São Paulo
The objective of this study was to compare the learning gains of three different student groups in first year high school who had contact with elementary concepts of statistics from Mathematics lessons (GM), Geography (GG) and Mathematics lessons applied interdisciplinary (statistics taught from Geography, Biology, Physics and Chemistry contents) (GI). To achieve this aim a study was done on a quasi-experimental basis which consisted of three groups of 35 students each at a public school in the state of São Paulo. It was applied two diagnostic tests (pre and post-test) at the study and the intervention was performed in each group by different teachers composing GM, GG and GI groups. The theoretical framework of this study included the theory of semiotics Records Offices of Raymond Duval (1995) about the change in registration; studies by Curcio (1989) and Wainer (1992) regarding to the levels of reading and interpreting data in graphs and tables respectively and the Literacy, Reasoning and Statistical Thinking with several authors as Cazorla (2002, 2005), Gal (2002), Lopes (2004), Morais (2006), Silva (2007) and Campos (2007). The interdisciplinary aspects were based on Fazenda (1994), Klein (2007) and Lenoir (2007) and the arithmetics in Novaes and Coutinho (2008). The study aimed to answer the following question: "What are the contributions that an educational intervention based on the principles of interdisciplinarity bring to the learning of statistics?" To answer this question the study was based on quantitative analysis of the results obtained in the tests applied to the three groups and a qualitative analysis of results presented by the students in the GI. The analysis showed a gain with the use of educational intervention at the three groups GM, GG and GI on the statistical study (construction, interpretation and arithmetic), but one significant performance was presented by students of the interdisciplinary group after educational intervention. This result allowed inferring that the teaching of Statistics based on an interdisciplinary approach proved its effectiveness as the interest of students in dealing with issues as well as their knowledge were reinforced by their understanding of statistical elements
O objetivo deste estudo foi comparar os ganhos de aprendizagem de três grupos de alunos da 1ª série do Ensino Médio que tiveram contato com conceitos elementares da Estatística a partir das aulas de Matemática (GM), de Geografia (GG) e de aulas de Matemática aplicadas de forma interdisciplinar (Estatística a partir de conteúdos de Geografia, Biologia, Física e Química) (GI). Para atingir este objetivo, foi feito um estudo de caráter do tipo quase-experimental que contou com três grupos compostos de 35 alunos de uma escola da rede pública estadual da cidade de São Paulo. No estudo foram aplicados dois testes diagnósticos (pré e pós-teste) e uma intervenção de ensino ocorrida em cada grupo, realizada por professores distintos que compunham os grupos GM, GG e GI. O quadro teórico do estudo contou com a teoria dos Registros de Representações Semiótica de Raymond Duval (1995) quanto à mudança de registro. Os estudos realizados por Curcio (1989) e Wainer (1992), quanto aos níveis de leitura e interpretação de dados em gráficos e tabelas, respectivamente; o Letramento, Raciocínio e Pensamento Estatístico com diversos autores como Cazorla (2002, 2005), Gal (2002), Lopes (2004), Morais (2006), Silva (2007) e Campos (2007). Quanto a interdisciplinaridade contou com Fazenda (1994), Klein (2007) e Lenoir (2007) e para a média aritmética com Novaes e Coutinho (2008). O estudo propôs-se a responder à seguinte questão: Quais as contribuições que uma intervenção de ensino pautada nos princípios da interdisciplinaridade traz para a aprendizagem da Estatística? Para responder à questão de pesquisa, tomou-se por base as análises quantitativas dos resultados obtidos nos testes aplicados nos três grupos e uma análise qualitativa dos resultados apresentados pelos alunos do grupo GI. As análises mostraram um ganho com a intervenção de ensino nos três grupos GM, GG e GI no que diz respeito aos elementos estatísticos estudados (construção, interpretação e média aritmética), porém um desempenho significativo foi apresentado pelos alunos do grupo da Interdisciplinaridade após a intervenção de ensino. O resultado permitiu inferir que o ensino de Estatística, pautado nos moldes da interdisciplinaridade mostrou-se eficaz quanto ao interesse por parte dos alunos em tratar de assuntos e, também, quanto ao ganho adquirido no que diz respeito ao conhecimento dos elementos estatísticos estudados

Les romans graphiques contemporains abordent des thématiques intimistes telles que l’autobiographie et le récit de la vie quotidienne. Ils se confrontent aux problématiques de représentation de l’indicible, de l’intériorité qui résiste à la monstration directe face auxquelles ils doivent inventer des modalités de dévoilement qui ne risquent pas de dénaturer l’intime. Pour ce faire, les artistes ont fréquemment recours à des procédés propres à d’autres médias, ou à des références à ceux-ci, qui créent une brèche dans la narration et la figuration, et permettent de laisser entrevoir l’intime. Le théâtre, la photographie, le carnet de voyage et de croquis, la danse et le cinéma font fréquemment irruption au détour d’une case et vont même jusqu’à modifier en profondeur la forme des roman graphiques. Il s’agira, à travers un corpus d’une quarantaine d’œuvres espagnoles contemporaines, intimistes et intermédiales, d’analyser les modalités de représentation de l’intime, de redéfinir ses enjeux au XXIème siècle, et de démontrer que les références intermédiales permettent de réarticuler le texte et l’image dans le roman graphique pour le suggérer. La Critique des dispositifs et l’approche intermédiale constituent des outils pertinents pour examiner les différents niveaux d’imbrication entre les différents médias, et leurs incidences sur la figuration de l’intime. La porosité intermédiale du roman graphique interroge également son statut médiatique et sa place dans le panorama éditorial et culturel contemporain. Ses rapports avec la bande dessinée et le roman s’avèrent en effet ambigus, puisqu’ils oscillent entre rapprochement et différenciation, tantôt affirmant, tantôt remettant en question l’indépendance médiatique du roman graphique. Il s’agira donc de déterminer, au terme de ce travail, si ce dernier s’est établi en tant que série culturelle séparée de la bande dessinée, ou s’il s’inscrit encore dans une phase d’émergence
Contemporary graphic novels address intimate themes such as autobiography and everyday life. They try to represent the unspeakable, the interiority that resists direct figuration, and they have to create modalities of disclosure that do not imply the distortion of intimacy. To do so, graphic novel artists often resort to strategies used by other media. They can also refer to them in order to cause a breach in the narrative and the figuration through which the reader can catch a glimpse of intimacy. Theater, photography, sketches or travelbooks, dance or cinema often break into the panel. They can even deeply modify the form of graphic novels. Analysing nearly forty intimate and intermedial contemporary Spanish graphic novels, this thesis studies the modalities of representation of intimacy. Moreover, it aims at defining its challenges in the 21st century. It also shows that intermedial references allow the artist to articulate the text and the image in a different way to suggest intimacy. Apparatus and intermediality theories turn out to be relevant tools to examine interconnection levels between different media, as well as their impact on the figuration of intimacy. The intermedial porosity of the graphic novel also questions its media status and its position in the contemporary editorial and cultural context. Its relations with the comic and the novel are ambiguous, since they oscillate between distancing and approaching. Moreover, on the one hand, they corroborate the mediatic independence of the graphic novel, while, on the other hand, they invalidate it. This thesis aims at finding out if the contemporary Spanish graphic novel is already established as a cultural series differentiated from the comic, or if it is still in an emerging stage
Las novelas gráficas contemporáneas tratan temáticas intimistas, por ejemplo la autobiografía o el relato del día a día. Plantean cómo representar lo indecible, la interioridad que resiste a la figuración directa, y tienen que inventar modalidades de desvelamiento que no impliquen la desvirtuación de lo íntimo. Entonces, los artistas recurren con frecuencia a estrategias propias de otros medios, o se refieren a ellos para crear brechas en la narración y en la imagen a través de las cuáles lo íntimo se deja entrever. El teatro, la fotografía, el libro de bocetos y de viaje, la danza o el cine irrumpen a menudo en las viñetas, y hasta pueden modificar en profundidad la forma de las novelas gráficas. Este trabajo observa, en unas cuarenta obras españolas contemporáneas, intimistas e intermédiales, las modalidades de representación de lo íntimo, y define sus retos en el siglo XXI. Demuestra también que las referencias intermediales permiten articular de una manera distinta el texto y la imagen en la novela gráfica para sugerirlo. La Crítica de los dispositivos y las teorías intermediales resultan ser herramientas pertinentes para examinar los niveles de interconexión entre los distintos medios, y sus incidencias en la figuración de lo íntimo. La porosidad intermedial de la novela gráfica también pone en tela de juicio su estatuto mediático y su ubicación en el panorama editorial y cultural contemporáneo. Sus relaciones con el cómic y la novela son ambiguas, puesto que oscilan entre distanciamiento y acercamiento, y que, por un lado, corroboran la independencia mediática de la novela gráfica, y, por otro lado, la invalidan. Esta tesis intenta averiguar si la novela gráfica española contemporánea ya está asentada como serie cultural diferenciada del cómic, o si sigue involucrada en una fase de emergencia

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Secretaria da Educação do Estado de São Paulo
The purpose of this study is to investigate the reading and interpretation of graphs and tables by specialist and non specialist teachers at Math, which act in Elementary School, with the objective of answering the following research question: What are the conceptions and competences that specialist and non specialist teachers at Math, which act in Elementary school have about basic concepts of Statistics? For such, a diagnostic research was developed with 40 teachers (20 polyvalent teachers G1 and 20 specialist at Math G2), coming from two schools of the public state network of the city of Mauá SP. The field work was constituted of two steps applying of the diagnostic tool, for both G1 and G2 and applying of semi-structured interviews in 10% of G1 and G2. The results obtained in each of these steps were analyzed, considering the object of the research reading and interpretation of graphs and tables as well as the four types of graphs used (column graph, line graph, sector graph and bar graph), a table of double entry and the concept of arithmetic average. The results showed the superiority of G2 over G1 and indicated that the conceptions and competences of teachers from both groups are still linked to a technicist view of Statistics, limited to a simple interpretation of basic concepts
Este estudo teve como objetivo investigar a leitura e a interpretação de gráficos e tabelas por professores especialistas e não especialistas em Matemática, que atuam no Ensino Fundamental, com a finalidade de responder à seguinte questão de pesquisa: Quais as concepções e competências que os professores especialistas e não especialistas em Matemática, que atuam no Ensino Fundamental têm sobre conceitos básicos de Estatística? Para tanto, foi desenvolvida uma pesquisa diagnóstica com 40 professores (20 polivalentes G1 e 20 especialistas em Matemática G2), advindos de duas escolas da rede pública estadual da cidade de Mauá SP. O trabalho de campo contemplou duas etapas aplicação do instrumento diagnóstico, tanto no G1 como no G2 e aplicação de entrevistas semi-estruturada em 10% de G1 e G2. Os resultados obtidos em cada uma das etapas foram analisados, considerando o objeto da pesquisa leitura e interpretação de gráficos e tabelas bem como os quatro tipos de gráficos usados (gráfico de colunas, gráfico de linhas, gráfico de setores e gráfico de barras), uma tabela de dupla entrada e o conceito de média aritmética. Os resultados evidenciaram a superioridade do G2 sobre o G1 e indicaram que as concepções e competências dos professores de ambos os grupos, ainda, se encontram vinculadas a uma visão tecnicista da Estatística, limitada a uma interpretação simples dos conceitos básicos

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The aim of this dissertation was to investigate 4th grade children's skills in reading and interpreting graphs as well as their conceptions of the statistical measure mean. More specifically, the study addressed the research question: What are the contributions of a teaching intervention based on the use of manipulative materials to the teaching and learning of elementary statistical concepts the primary school? To this end, an interventionist research approach was adopted in a study involving two classes of the fourth year of "Ensino Fundamental" in a public school in São Paulo. One class constituted the control group (GC) and the other the experimental group (GE). The field research was organised in two phases the administration of diagnostic instruments (pre- and post-tests) to both the experimental and control groups; and the teaching intervention, which was applied only with the experimental group. The results from each phase were analysed in relation to two research foci the reading and interpretation of graphs and the concept of arithmetic mean and in relation to the types of graphs used vertical-bar graphs and "two-entry" graphs (as represented in the software Tabletop). Analysis of the results indicated student difficulties in the reading and interpreting of graphs in particular situations, such as graphs with non-unitary scales and/or with null frequency; The reading and interpretation of two-entry graphs was not associated with major difficulties. For the arithmetic mean, an increase of almost 50% in students' performance was observed from comparisons of the pre-and post-test results. On the basis of these results, it appears that the teaching intervention enabled the development of strategies for solving the presented situations as well as favouring the forging of important relations between the two concepts investigated, which influenced the amplification of students' knowledge of Data Handling
O objetivo desta dissertação foi investigar o desenvolvimento da leitura e interpretação de gráficos e o conceito de média aritmética por crianças da 4ª série do Ensino Fundamental, por meio de uma intervenção de ensino com o uso de material manipulativo, a fim de responder à seguinte questão de pesquisa: Quais as contribuições de uma intervenção de ensino com o uso de material manipulativo para o ensino-aprendizagem de conceitos elementares de Estatística nas séries iniciais do Ensino Fundamental? Para tanto, foi desenvolvida uma pesquisa de caráter intervencionista com alunos de duas classes de 4ª série do Ensino Fundamental de uma escola da rede pública estadual de São Paulo; uma delas constituiu-se em grupo controle (GC) e a outra em grupo experimental (GE). A pesquisa de campo contemplou duas etapas aplicação dos instrumentos diagnósticos (pré e pós-testes), tanto no GE como no GC e aplicação da intervenção de ensino com uso de material manipulativo apenas no GE. Os resultados obtidos em cada uma dessas etapas foram analisados considerando os dois objetos da pesquisa a leitura e interpretação de gráficos e o conceito de média aritmética bem como os dois tipos de gráficos usados gráfico de barras verticais e gráfico de dupla entrada (extraído do software Tabletop). Os resultados apontaram para as dificuldades dos alunos na leitura e interpretação de gráficos em situações específicas, como gráficos com escalas não unitárias e ou com freqüência nula. A leitura e interpretação do gráfico de dupla entrada não apresentou maiores dificuldades. Quanto à média aritmética, os resultados mostraram um crescimento de quase 50% no desempenho dos alunos do GE, no pós-teste. Tendo por base tais resultados pode-se concluir que a associação da intervenção de ensino com o material manipulativo possibilitou o desenvolvimento de estratégias para a resolução das situações apresentadas e permitiu o estabelecimento de importantes relações entre os dois conteúdos abordados, as quais, por sua vez, influenciaram na ampliação do conhecimento do aluno sobre o Tratamento da Informação

Technologies de communication écrite et langage numérique sont les clés qui ont ouvert l’espace à une réflexion portant sur l’impact de ces technologies et de ce type de langage sur les écrits des collégiens et lycéens francophones. L’âge de ces jeunes qui correspond à la période de l’adolescence et à sa transformation physiologique, ainsi que l’émergence d’une évolution technologique et l’envahissement des supports numériques (notamment “le smartphone”) ont joué un rôle dans la modification, au moins partielle, de la langue française notamment dans le domaine des écrits scolaires. L’acte d’écrire n’est plus considéré comme réglementé, au contraire, il est devenu oralisé, déréglé, regroupant le son et la graphie, répondant aux désirs rédactionnels des adolescents. Mais certaines variations dans ce nouvel acte d’écriture numérique ne sont pas créées à partir d’un vide, elles reviennent à des formes d’écrit autrefois utilisées dans les écrits traditionnels, ce qui constitue l’un des points importants du sujet de notre recherche. L’impact de l’utilisation des outils numériques sur la qualité de la langue, surtout de l’orthographe, est souvent considéré par le grand public comme néfaste. D’une manière générale, notre objet est défini à travers les études réalisées autour de ce sujet qui n’ont pas affirmé la négativité absolue du nouveau langage numérique sur les productions d’écrits des élèves, c’est pourquoi certaines suggestions sont indiquées pour un meilleur apprentissage de la langue
Written communication technologies and digital language are the keys that have opened the space for reflection on the impact of such technologies and type of language on the writings of francophone college and high school students. The age of these young people, which corresponds to the period of adolescence and its physiological transformation, as well as the emergence of technological evolution and the invasion of digital media (notably "the smartphone") played a role in the modification, at least partially, of the French language, particularly in the field of school writing. The act of writing is no longer considered as regulated, on the contrary, it has become oral-oriented, without rules, grouping together sound and writing and responding to the editorial desires of adolescents. On the other hand, certain variations in this new act of digital writing are not created from vacuum, they trace back to forms of writing formerly used in traditional writings, which constitutes one of the important points of the subject of our research. The impact of the use of digital tools on the quality of language, especially spelling, is often considered by the general public as harmful. In general, our object is defined through the studies carried out around this subject which did not affirm the absolute negativity of the new numerical language on the productions of writings of the students, which is why certain suggestions are indicated for better learning of language

Esta tese de doutorado aborda os tópicos de modelagem e de reconhecimento de objetos estruturados, ou sistemas estruturados de objetos, em imagens. Um objeto ou sistema estruturado é aquele que pode ser descrito através de elementos primitivos que o compõem e pelas relações existentes entre esses elementos. Por exemplo, uma aeronave pode ser descrita pelos seguintes elementos primitivos: asas direita e esquerda, fuselagem e cockpit. O aspecto relacional de um objeto estruturado direciona sua representação computacional e seu reconhecimento em imagens ao paradigma estrutural de reconhecimento de padrões. Contudo, a variabilidade das características dos seus elementos primitivos é melhor representada através do paradigma estatístico de reconhecimento de padrões. Devido à complementaridade dos paradigmas, a conjunção dessas abordagens é um tema de pesquisa de interesse atual. Para conjugar esses dois aspectos, esta tese propôs uma metodologia que combina o conhecimento a priori das relações que caracterizam um objeto estruturado com dados estatísticos coletados de amostras desse objeto, num modelo híbrido denominado grafo estatístico-relacional (GER). Segundo essa representação, foi estudada uma abordagem probabilística para reconhecer um objeto estruturado em imagens. Nesse cenário, o GER modelo é considerado uma variável aleatória, enquanto uma rotulação de uma imagem de entrada é interpretada como uma potencial observação do modelo. A tarefa de reconhecimento foi então formulada como um problema de otimização, que busca maximizar a probabilidade da observação de acordo com o modelo. O método foi aplicado à modelagem de órgãos abdominais em imagens de ressonância magnética não-contrastadas. Esses órgãos apresentam um arranjo espacial consistente em imagens distintas, além de propriedades de aparência e anatômicas variáveis, o que vem ao encontro da proposta da representação por GER e da abordagem probabilística para o reconhecimento dos órgãos em novas imagens.
The purpose of this thesis was to propose a formalism for the problems of modeling and recognition of a structured object, or a system of structured objects, in images. A structured object is one that may be described in terms of its compound primitive elements and their inherent relations. For instance, an aircraft may be described in terms of the following primitives: right and left wings, fuselage, and cockpit. The relational aspect of structured objects leads these problems to solutions in structural pattern recognition, which describes patterns as primitives and relations. Nevertheless, the variability of primitive elements and of their relations is better modeled by traditional statistical pattern recognition methods. Because of the complementary capabilities of these approaches, the fusion of both has recently been pointed out as a trend in computer vision. To consider these sources of information, the methodology presented herein combines relational cues inherent to a structured object with statistical information learned from a set of object samples. A hybrid model of a structured object is represented by means of a statistical relational graph (SRG). The SRG is a prototype attributed relational graph (ARG) in which nodes represent primitive elements and arcs link nodes representing related primitives. Each node or arc is associated with attributes which are parameters of probability distributions that describe random variables representing primitive or relational attributes. Based on this representation, a probabilistic approach was proposed to tackle the problem of recognizing a structured object in an input image. The model SRG is interpreted as a random variable, whereas a labeling of the input image is considered a potential observation of the model. The recognition task was formulated as the optimization of an objective-function that is actually a probability measure to be maximized. The proposed approach was applied to the modeling of abdominal organs in non-contrasted magnetic resonance images. These organs present consistent spatial arrangement in distinct images, as well as varying appearance and anatomical properties, which meet the principle of the SRG representation and the associated probabilistic recognition scenario.

Cette étude est consacrée à la revue G : Material zur elementaren Gestaltung, publiée par Hans Richter à Berlin entre 1923 et 1926. Située au croisement de Dada, De Stijl, du Bauhaus et du constructivisme russe, G réunit un groupe hétérogène d’artistes, d’architectes et de cinéastes d’avant-garde, parmi lesquels on compte notamment Theo van Doesburg, Mies van der Rohe, El Lissitzky, Ludwig Hilberseimer, Kurt Schwitters, Hans Arp, Werner Gräff et Viking Eggeling. Après l’analyse des aspects concrets de sa publication (édition et diffusion), de son format et design graphique, et après la reconstitution des étapes de sa fondation autour du collectif spécifique que formait le « groupe G », nous étudions l’ancrage de G dans le réseau international des revues, en mettant en lumière sa fonction de plaque tournante entre les avant-gardes d’Europe de l’Ouest et d’Europe centrale, de l’Est et de Russie. Nous examinons ensuite la spécificité de son projet esthétique, articulé autour de la « configuration élémentaire » [elementare Gestaltung] de divers matériaux (articles, photographies, objets d’art et d’architecture, objets techniques, objets de mode et de loisirs) selon le principe de l’économie des moyens. Nous réinscrivons enfin le projet artistique et intellectuel de la revue dans la dimension politique contemporaine, en montrant que son engagement réside dans sa dynamique internationaliste et collective, dans le potentiel émancipateur qu’elle accorde aux nouveaux médias (exploiter les possibilités du médium filmique pour transformer la perception sensible) et dans sa volonté de reconfigurer radicalement l’environnement matériel et culturel de l’homme
This study focuses on the magazine G : Material zur elementaren Gestaltung, published by Hans Richter in Berlin between 1923 and 1926. Standing at the crossroads of Dada, De Stijl, Bauhaus and russian constructivism, G brought together an eclectic group of avant-garde artists, architects and filmmakers (among which Theo van Doesburg, Mies van der Rohe, El Lissitzky, Ludwig Hilberseimer, Kurt Schwitters, Hans Arp, Werner Gräff and Viking Eggeling). After the analysis of the concrete aspects of its publication (edition and distribution), of its format and graphic design, and after the reconstruction of the different steps of its foundation around the specific constellation formed around the “Group G”, we examine G’s connection to the international network of avant-garde magazines, by showing its turntable role between the avant-gardes of Western and Central-Eastern Europe and Russia. We then analyse its specific aesthetic project, based on the “elemental configuration” [elementare Gestaltung] of various materials (articles, photographs, artistic and architectural objects, technical objects, fashion and leisure objects), according to the principle of the economy of means. Finally, we resituate G’s artistic and intellectual project within the contemporary political dimension, by showing that its engagement consisted in its internationalist orientation and collective organisation, in the emancipatory potential assigned to new media (one main objective was to exploit all the possibilities of film medium in order to transform human perception) and in its desire to radically reconfigure the material and cultural environment of human being

Structure learning of Bayesian Networks (BNs) is an NP-hard problem, and the use of sub-optimal strategies is essential in domains involving many variables. One of them is to generate multiple approximate structures and then to reduce the ensemble to a representative structure. It is possible to use the occurrence frequency (on the structures ensemble) as the criteria for accepting a dominant directed edge between two nodes and thus obtaining the single structure. In this doctoral research, it was made an analogy with an adapted one-dimensional random-walk for analytically deducing an appropriate decision threshold to such occurrence frequency. The obtained closed-form expression has been validated across benchmark datasets applying the Matthews Correlation Coefficient as the performance metric. In the experiments using a recent medical dataset, the BN resulting from the analytical cutoff-frequency captured the expected associations among nodes and also achieved better prediction performance than the BNs learned with neighbours thresholds to the computed. In literature, the feature accounted along of the perturbed structures has been the edges and not the directed edges (arcs) as in this thesis. That modified strategy still was applied to an elderly dataset to identify potential relationships between variables of medical interest but using an increased threshold instead of the predict by the proposed formula - such prudence is due to the possible social implications of the finding. The motivation behind such an application is that in spite of the proportion of elderly individuals in the population has increased substantially in the last few decades, the risk factors that should be managed in advance to ensure a natural process of mental decline due to ageing remain unknown. In the learned structural model, it was graphically investigated the probabilistic dependence mechanism between two variables of medical interest: the suspected risk factor known as Metabolic Syndrome and the indicator of mental decline referred to as Cognitive Impairment. In this investigation, the concept known in the context of BNs as D-separation has been employed. Results of the carried out study revealed that the dependence between Metabolic Syndrome and Cognitive Variables indeed exists and depends on both Body Mass Index and age.
O aprendizado da estrutura de uma Rede Bayesiana (BN) é um problema NP-difícil, e o uso de estratégias sub-ótimas é essencial em domínios que envolvem muitas variáveis. Uma delas consiste em gerar várias estruturas aproximadas e depois reduzir o conjunto a uma estrutura representativa. É possível usar a frequência de ocorrência (no conjunto de estruturas) como critério para aceitar um arco dominante entre dois nós e assim obter essa estrutura única. Nesta pesquisa de doutorado, foi feita uma analogia com um passeio aleatório unidimensional adaptado para deduzir analiticamente um limiar de decisão apropriado para essa frequência de ocorrência. A expressão de forma fechada obtida foi validada usando bases de dados de referência e aplicando o Coeficiente de Correlação de Matthews como métrica de desempenho. Nos experimentos utilizando dados médicos recentes, a BN resultante da frequência de corte analítica capturou as associações esperadas entre os nós e também obteve melhor desempenho de predição do que as BNs aprendidas com limiares vizinhos ao calculado. Na literatura, a característica contabilizada ao longo das estruturas perturbadas tem sido as arestas e não as arestas direcionadas (arcos) como nesta tese. Essa estratégia modificada ainda foi aplicada a um conjunto de dados de idosos para identificar potenciais relações entre variáveis de interesse médico, mas usando um limiar aumentado em vez do previsto pela fórmula proposta - essa cautela deve-se às possíveis implicações sociais do achado. A motivação por trás dessa aplicação é que, apesar da proporção de idosos na população ter aumentado substancialmente nas últimas décadas, os fatores de risco que devem ser controlados com antecedência para garantir um processo natural de declínio mental devido ao envelhecimento permanecem desconhecidos. No modelo estrutural aprendido, investigou-se graficamente o mecanismo de dependência probabilística entre duas variáveis de interesse médico: o fator de risco suspeito conhecido como Síndrome Metabólica e o indicador de declínio mental denominado Comprometimento Cognitivo. Nessa investigação, empregou-se o conceito conhecido no contexto de BNs como D-separação. Esse estudo revelou que a dependência entre Síndrome Metabólica e Variáveis Cognitivas de fato existe e depende tanto do Índice de Massa Corporal quanto da idade.

Breast cancer is one of the leading causes of death in the world, affecting mostly women. The most common treatments for this disease include radio- and chemo-therapies. However, these therapeutic approaches have a sub-optimal efficacy and can induce adverse side effects to patients. In this way, there is an urgent demand for the development of novel breast cancer treatments. To improve the breast cancer treatment, researchers are developing new therapeutic approaches. In particular, photothermal therapy (PTT) mediated by nanomaterials has captured the attention of researchers and clinicians. This type of therapy takes advantage from the physicochemical and optical properties of some light-responsive nanostructures. These can accumulate preferentially in the tumor zone, and induce, after external irradiation with near infrared (NIR) light, a temperature increase that can damage cancer cells. In this thesis, reduced graphene oxide (rGO) was produced by using an environmentally-friendly method. Then rGO was functionalized with a novel hyaluronic acid (HA)-based amphiphilic polymer to be applied in targeted breast cancer PTT. HA was selected due to its hydrophilic character and targeting capacity to the CD44 receptors, which are overexpressed on breast cancer cells’ membrane. The obtained results revealed that the treatment of graphene oxide with L-ascorbic acid (3 mM) for 60 minutes at 80 °C is ideal considering the NIR absorption and the size distribution of the obtained materials. Then, rGO was functionalized with the HA-based amphiphilic polymer through non-covalent interactions. The functionalization of rGO improved its stability, cytocompatibility, and internalization by CD44 overexpressed by breast cancer cells, which indicates the targeting capacity of this nanoformulation. Furthermore, the on-demand PTT mediated by HA functionalized rGO induced cancer cells’ death, thereby confirming the potential of this nanoformulation for targeted breast cancer therapy.
O cancro da mama é uma das principais causas de morte em todo o mundo, afetando principalmente as mulheres. Os tratamentos mais comuns para esta doença incluem a radioterapia e a quimioterapia. No entanto, estas abordagens terapêuticas apresentam uma baixa eficácia e podem, também, induzir efeitos secundários adversos nos pacientes. Desta forma, existe uma enorme necessidade em desenvolver novos tratamentos mais eficazes para o cancro da mama. Neste contexto, diferentes investigadores estão a desenvolver novas abordagens terapêuticas. Em particular, a terapia fototérmica mediada por nanomateriais tem recebido um interesse crescente por parte dos investigadores e profissionais de saúde. Esta abordagem tira partido das propriedades físico-químicas e óticas de alguns tipos de nanomateriais. Estas nanoestruturas responsivas à luz conseguem acumular-se preferencialmente na zona tumoral e posteriormente induzir, após irradiação com luz com um comprimento de onda na região do infravermelho próximo (NIR), um aumento de temperatura que pode danificar as células cancerígenas. Nesta dissertação, materiais à base de óxido de grafeno reduzido (rGO) foram produzidos através de um método de redução ecológico e funcionalizados com um novo polímero anfifílico à base de ácido hialurónico (HA) para aplicação na terapia fototérmica do cancro da mama. O HA foi escolhido devido ao seu carácter hidrofílico e por possuir capacidade de direcionamento para os recetores CD44, que são sobreexpressos na membrana citoplasmática das células do cancro da mama. Os resultados obtidos revelaram que o tratamento do óxido de grafeno com ácido L-ascórbico (3 mM), durante 60 minutos, a 80 ºC, constituem as condições ideais de redução tendo em conta a absorção no NIR apresentada pelo rGO e a distribuição de tamanhos dos materiais obtidos. Posteriormente, a funcionalização do rGO com o polímero anfifílico à base de HA foi efetuada através de interações não-covalentes. A funcionalização melhorou a estabilidade, citocompatibilidade e internalização dos nanomateriais pelas células do cancro da mama que sobreexpressam o recetor CD44, o que confirma a capacidade de direcionamento desta nanoformulação. Adicionalmente, a terapia fototérmica mediada pelo rGO funcionalizado induziu a morte das células cancerígenas, confirmando assim o potencial desta nanoformulação para aplicação na terapia direcionada do cancro da mama.

Breast cancer remains as one of the deadliest diseases affecting the worldwide population. The high mortality rate exhibited by this disease can be attributed to the limitations of the treatments currently in use in the clinic (e.g. radiotherapy, chemotherapy), which display a low therapeutic efficacy and induce adverse side effects in patients. Therefore, there is an urgent demand for innovative therapeutic approaches that can enhance breast cancer survival rates. Recently, nanomaterials’ mediated Photothermal Therapy (PTT) has been showing promising results for cancer treatment. This therapeutic modality employs nanostructures that, due to their specific set of physicochemical characteristics, can accumulate at the tumor site. Afterwards, this zone is irradiated with Near Infrared (NIR) light and the tumor-homed nanomaterials induce a local temperature increase (hyperthermia) that can induce damage to cancer cells. Among the several nanomaterials with potential for cancer PTT, Graphene Oxide (GO) has been extensively investigated due to its absorption in the NIR. After interacting with this radiation, GO produces a temperature increase that can cause damage to cancer cells. In addition, this nanomaterial has an aromatic matrix that can be used to encapsulate a wide variety of compounds, thus having a great versatility. However, the direct application of GO in cancer PTT is limited by two factors: i) the low colloidal stability of GO, which causes its precipitation in biological fluids, and ii) the poor photothermal capacity of GO, which leads to the use of high doses/intense radiation in order to achieve an adequate therapeutic effect. In this MSc research work, GO was functionalized with an albumin based amphiphilic coating containing Sulfobetaine Methacrylate (SBMA) brushes (SBMA-g-BSA) and was loaded with IR780, with the intent to improve its colloidal stability and photothermal capacity, respectively. The results revealed that GO functionalized with SBMA-g-BSA (SBMA-BSA/GO) presents an adequate size distribution and cytocompatibility for cancer-related applications. When in contact with biologically relevant media, the size of the SBMA-functionalized GO derivatives only increased by 8 % after 48 h. In the same condition and period, the non-SBMA functionalized GO (BSA coated GO) suffered a 31 % increase in its size. By loading IR780 into SBMA-BSA/GO (IR/SBMA-BSA/GO), the nanomaterials’ NIR absorption increased by 5.6-fold. In this way, the IR/SBMA-BSA/GO could produce a up to 2-times higher photoinduced heat than SBMA-BSA/GO. In in vitro cell studies, the combination of NIR light with SBMA-BSA/GO did not induce photocytotoxicity on breast cancer cells. In stark contrast, the interaction of IR/SBMA-BSA/GO with NIR light caused the ablation of cancer cells (cell viability < 2 %). Overall, IR/SBMA-BSA/GO displays a greatly improved colloidal stability and phototherapeutic capacity, being a promising hybrid nanomaterial for application in the PTT of breast cancer cells.
O cancro da mama é uma das doenças com maior taxa de mortalidade associada. Este facto está relacionado com a baixa eficácia das terapias, como por exemplo a radio e a quimioterapia, usadas em meio clínico. Para ultrapassar esta baixa eficácia e os efeitos secundários associados, os investigadores têm procurado desenvolver novas abordagens para o tratamento do cancro da mama. Recentemente, a Terapia Fototérmica (do inglês Photothermal Therapy (PTT)) mediada por nanomateriais tem apresentado resultados bastante promissores. Nesta modalidade terapêutica, os nanomateriais, devido às suas características físico-químicas, conseguem acumular-se no tumor. Posteriormente, a zona tumoral é irradiada com luz com comprimento de onda na região do infravermelho próximo (do inglês Near Infrared (NIR)). A interação da luz NIR com os nanomateriais acumulados no tumor induz um aumento de temperatura local (hipertermia), que pode causar a morte das células cancerígenas. De entre os vários nanomateriais que têm sido estudados para aplicação na PTT do cancro, o Óxido de Grafeno (do inglês Graphene Oxide (GO)) tem sido amplamente explorado devido à sua absorção no NIR. Após interação com esta radiação, o GO produz um aumento de temperatura que pode causar danos celulares. Para além disto, este nanomaterial tem uma matriz aromática que lhe permite encapsular uma grande variedade de compostos, exibindo, portanto, uma grande versatilidade. No entanto, a aplicação direta do GO na PTT do cancro é limitada por dois fatores: i) a baixa estabilidade coloidal do GO, o que faz com que precipite em fluidos biológicos, e ii) a fraca capacidade fototérmica do GO, o que conduz à administração de doses elevadas/uso de radiação intensa para alcançar um efeito terapêutico adequado. No trabalho de investigação que desenvolvi durante o meu mestrado, o GO foi funcionalizado com um conjugado de Metacrilato de Sulfobetaína-Albumina de Soro Bovino (SBMA-g-BSA) e o IR780 foi encapsulado na sua estrutura, com o intuito de melhorar a sua estabilidade coloidal e capacidade fototérmica, respetivamente. Os resultados obtidos mostraram que o GO funcionalizado com SBMA-g-BSA (SBMA-BSA/GO) apresenta uma distribuição de tamanhos e citocompatibilidade adequadas para a sua aplicação na terapia do cancro. Quando o SBMA-BSA/GO foi colocado em contacto com meio com relevância biológica, o seu tamanho apenas aumentou em 5 % durante 48 h. Por outro lado, o GO revestido apenas com BSA (sem funcionalização de SBMA) teve um acréscimo de 31 % no seu tamanho neste período. Ao encapsular o IR780 na estrutura grafítica do GO, a absorção deste nanomaterial na zona do NIR aumentou em cerca de 5,6 vezes, o que permitiu duplicar a sua capacidade fototérmica. Nos estudos realizados in vitro, a viabilidade das células do cancro da mama não foi afetada pela sua incubação com SBMA-BSA/GO juntamente com radiação NIR. Por outro lado, a combinação de IR/SBMA-BSA/GO com irradiação NIR induziu a morte destas células (viabilidade celular inferior a 2 %). Assim, o IR/SBMA-BSA/GO apresenta estabilidade coloidal e capacidade fototerapêutica melhoradas, sendo um nanohíbrido promissor para a aplicação na PTT do cancro da mama.

ANOTATION This thesis examines a discourse of photography and poster, with the aim to join these two phenomena into a single summary theory and create their general characteristics. The work searches for intersections between photography and graphic design/poster and applies them in the theory of poster creation. In the didactic part, the theoretical principles are introduced into teaching art classes at primary schools. The same approach is applied in the artwork itself. Keywords: Photography, grafic design, poster, photo poster, new media, typography

O conceito de sustentabilidade resume-se à noção de desenvolvimento económico, social e ambiental, de forma a não provocar danos significativos ao ambiente e aos recursos naturais existentes. Nos dias de hoje, o crescimento da população é uma das questões mais preocupantes, sendo indispensável repensar o problema dos desperdícios originados pelas indústrias agroalimentares. Anualmente, estas indústrias desperdiçam toneladas de resíduos que pouca ou nenhuma utilização têm. Contudo, grande parte destes desperdícios alimentares contém quantidades consideráveis de compostos bioatividade, cuja atividade pode ter diversas aplicações, sendo de destacar a produção de nutracêuticos. As indústrias agroalimentares produtoras e/ou transformadoras de azeite, vinho, café e castanha geram uma grande quantidade de resíduos alimentares potencialmente atrativos para outras indústrias, que os podem reutilizar com vista a aumentar a sua produtividade e lucro. Tendo em conta este problema, este trabalho de conclusão de ciclo tenta mostrar a importância do reaproveitamento dos resíduos alimentares com maior expressão a nível económico, ambiental e social. Dados as características químicas e os efeitos benéficos que estes resíduos alimentares podem causar à saúde humana, a sua reutilização para a formação de novos produtos pode ser vantajosa para as indústrias farmacêuticas, cosméticas e alimentares.
Sustainability is summed up as the concept of economic, social and environmental development in way that doesn’t cause significant damage to the environment and existing natural resources. Nowadays, population growth is one of the most concerning factors and it is imperative to rethink the issue of the waste that originates from the agrifood sector. Every year, these industries produce tons of waste with very little utility. However, most of the food waste has considerable amounts of bioactive compounds, whose activity can be used to produce nutraceuticals. The agri-food and/or manufacturing industries that produce olive oil, wine, coffee and chestnut produce an enormous amount of food waste that are potentially attractive to other industries that will reuse them with the goal of increasing their profit and productivity. Considering this issue, this work of conclusion of period tries to show the importance of reusing food waste with bigger economical, environmental and social impact. Given the chemical characteristics and the beneficial effects this waste can cause to human health, its reuse to create new products can be an advantage for the pharmaceutical, cosmetic and food industries.