Atualmente empresas como Google e Facebook fazem parte da lista das maiores companhias do mundo. O investimento em publicidade e criação de páginas para a divulgação de anúncios e marcas, tem levado o Facebook a uma posição de destaque neste cenário. Neste contexto, o presente trabalho tem o objetivo de analisar e predizer o número de interações em notícias divulgadas em cinco páginas de fãs, que se constituem nas mais acessadas da Rede Social Facebook no Brasil. Como contribuição propõem-se determinar o fator de impacto de publicações, considerando a média de três características mencionadas, o número de curtidas, o número de comentários e o número de vezes que a notícia foi compartilhada. Serão avaliados resultados da aplicação de diferentes técnicas para a classificação, além da influência de características relacionadas a palavras e termos mais frequentes, verificando qual combinação produz melhores resultados no processo de gerar um modelo de aprendizado para prever o Fator de Impacto de notícias publicadas nas páginas de fãs da Rede Social Facebook. Apresenta-se também os motivos que podem exercer influência no fator de impacto através do processo de descoberta de conhecimentos em base de dados e também fazendo uso de técnicas de processamento de linguagem natural com o objetivo de atender a expectativa do trabalho. / Currently companies as Google and Facebook are on the top of the largest companies in the world and according to news released on the website tecmundo the main reason that led to this privileged position, in particular Facebook, appears to be the result of its investments in publicity focused on mobile devices through general advertisements in its own social network. In this context the present research aims to estimate the number of news interactions published on the five most accessed fans pages of Facebook Social Network in Brazil. Are considered examples of interactions in this study the number of likes, the number of comments and also the amount of times a message was shared. As also disclose attributes that influence interactions. As a contribution is proposed the impact factor of a publication, considering the average of three mentioned interactions, the number of likes, the number of comments and also the number of times the news was shared, in order to improve the results in predicting interactions of a fan page of Facebook Social Network. In addition to analyze the results of prediction algorithms applying different techniques of text pre- processing checking which combination produces best results in generating a learning process model to foresee the impact of news published on Facebooks fan pages and exhibit reasons that may influence the impact factor through the discovering process of database knowledge, from the feeling analysis as well as making use of processing of natural language techniques in order to fulfill work expectation.

Recentemente, as medidas de centralidade ganharam relevância nas pesquisas com redes complexas e redes sociais, atuando como preditores comportamentais, na identificação de elementos de poder e influência, na detecção de pontos estratégicos para a comunicação e para a transmissão de doenças. Novas métricas foram criadas e outras reformuladas, mas pouco tem sido feito para que se entenda a relação existente entre as diferentes medidas de centralidades, assim como sua relação com outras propriedades estruturais das redes em que elas são frequentemente aplicadas. Nossa pesquisa visa analisar e estudar essas relações para que sirvam de guia na aplicação das medidas de centralidade existentes em novos contextos e aplicações. Nós apresentamos também evidencias que indicam um desempenho superior das medidas conhecidas como Walk Betweenness, Information, Eigenvector and Betweenness na distinção de vértices das redes somente pelas suas características estruturais. Ainda, nós propiciamos detalhes sobre o desempenho distinto de cada métrica de acordo com o tipo de rede em que se trabalha. Adicionalmente, mostramos que várias das medidas de centralidade apresentam um alto nível de redundância e concordância entre si (com correlação superior a 0,8). Um forte indício que o uso simultâneo de várias métricas é improdutivo ou pouco eficaz. Os resultados da nossa pesquisa reforçam a ideia de que para usar apropriadamente as medidades de centralidade é de extrema importância que se saiba mais sobre o comportamento e propriedades das mesmas, fato que salientamos nessa dissertação. / Over the last years, centrality measures have gained importance within complex and social networks research, e.g., as predictors of behavior, identification of powerful and influential elements, detection of critical spots in communication networks and in transmission of diseases. New measures have been created and old ones reinvented, but few have been proposed to understand the relation among measures as well as between measures and other structural properties of the networks. Our research analyzes and studies these relations with the objective of providing a guide to the application of existing centrality measures for new environments and new purposes. We shall also present evidence that the measures known as Walk Betweenness, Information, Eigenvector and Betweenness are substantially better than other metrics in distinguishing vertices in a network by their structural properties. Furthermore, we provide evidence that each metric performs better with respect to distinct kinds of networks. In addition, we show that most metrics present a high level of redundancy (over 0.8 correlation) and its simultaneous use, in most cases, is fruitless. The results achieved in our research reinforce the idea that to use centrality measures properly, knowledge about their underlying properties and behavior is valuable, as we show in this dissertation.

abstract: Although aggression is sometimes thought to be maladaptive, evolutionary theories of resource control and dominance posit that aggression may be used to gain and maintain high social prominence within the peer group. The success of using aggression to increase social prominence may depend on the form of aggression used (relational versus physical), the gender of the aggressor, and the prominence of the victim. Thus, the current study examined the associations between aggression and victimization and social prominence. In addition, the current study extended previous research by examining multiple forms of aggression and victimization and conceptualizing and measuring social prominence using social network analysis. Participants were 339 6th grade students from ethnically diverse backgrounds (50.4% girls). Participants completed a peer nomination measure assessing relational and physical aggression and victimization. They also nominated friends within their grade, which were used to calculate three indices of social prominence, using social network analysis. As expected, results indicated that relational aggression was associated with higher social prominence, particularly for girls, whereas physical aggression was less robustly associated with social prominence. Results for victimization were less clear, but suggested that, for girls, those at mid-levels of social prominence were most highly victimized. For boys, results indicated that those both high and low in prominence were most highly relationally victimized, and those at mid-levels of prominence were most highly physically victimized. These findings help inform intervention work focused on decreasing overall levels of aggressive behavior. / Dissertation/Thesis / M.S. Family and Human Development 2013

abstract: As networks are playing an increasingly prominent role in different aspects of our lives, there is a growing awareness that improving their performance is of significant importance. In order to enhance performance of networks, it is essential that scarce networking resources be allocated smartly to match the continuously changing network environment. This dissertation focuses on two different kinds of networks - communication and social, and studies resource allocation problems in these networks. The study on communication networks is further divided into different networking technologies - wired and wireless, optical and mobile, airborne and terrestrial. Since nodes in an airborne network (AN) are heterogeneous and mobile, the design of a reliable and robust AN is highly complex. The dissertation studies connectivity and fault-tolerance issues in ANs and proposes algorithms to compute the critical transmission range in fault free, faulty and delay tolerant scenarios. Just as in the case of ANs, power optimization and fault tolerance are important issues in wireless sensor networks (WSN). In a WSN, a tree structure is often used to deliver sensor data to a sink node. In a tree, failure of a node may disconnect the tree. The dissertation investigates the problem of enhancing the fault tolerance capability of data gathering trees in WSN. The advent of OFDM technology provides an opportunity for efficient resource utilization in optical networks and also introduces a set of novel problems, such as routing and spectrum allocation (RSA) problem. This dissertation proves that RSA problem is NP-complete even when the network topology is a chain, and proposes approximation algorithms. In the domain of social networks, the focus of this dissertation is study of influence propagation in presence of active adversaries. In a social network multiple vendors may attempt to influence the nodes in a competitive fashion. This dissertation investigates the scenario where the first vendor has already chosen a set of nodes and the second vendor, with the knowledge of the choice of the first, attempts to identify a smallest set of nodes so that after the influence propagation, the second vendor's market share is larger than the first. / Dissertation/Thesis / Ph.D. Computer Science 2014

O aumento na disponibilidade de dados referentes a interação entre pessoas online tornou possível o estudo o processo de propagação de informações em redes sociais com volumes de dado antes jamais pensados. Neste trabalho, utilizamos dados do site de micro-blogging Twitter juntamente com conceitos de redes complexas para entender, caracterizar e classificar processos de difusão de informação observados nessa plataforma e em redes sociais em geral. Apresentamos importantes medidas para caracterização de cascatas de informação, bem como algoritmos eficientes para o seu cálculo. Com o auxilio dessas, mostramos que é possível quantificar a influência da rede social no processo de propagação de informação. Em seguida, constatamos que a informação tende a propagar por caminhos mínimos nessa rede. Por fim, mostramos que é possível utilizar apenas a topologia da rede social, sem nenhuma informação semântica, para agrupar tópicos, e que a topologia da rede social é fortemente influenciada pelos assuntos falados nela. Apesar de nosso trabalho possuir como base um único dataset, os métodos e medidas desenvolvidos são gerais e podem ser aplicados a qualquer processo de difusão de informação e a qualquer rede complexa. / The raise in the availability of data regarding interactions between people online has opened new doors to study the process of information diffusion in social networks. In this present work, we make use of the data from the micro-blogging website Twitteralong with complex networks concepts to understand, characterize and classify information diffusion processes observed in this platform and in social networks in general. We present important measures to characterize information cascades and efficient algorithms to calculate them. With the help of these measures, we show that it is possible to quantify the influence of the social network in the process of information diffusion. After that, we show that information does tend to travel along shortest paths on Twitter. Finally, we show that the topology of the social network, without any extra semantic information, can be used to aggregate topics, and that such topology is highly influenced by the topics being discussed on it. Altough we work with only a single dataset, our methods and measures developed are general and can be applied to any process of information diffusion and any complex network.

Recentemente, as medidas de centralidade ganharam relevância nas pesquisas com redes complexas e redes sociais, atuando como preditores comportamentais, na identificação de elementos de poder e influência, na detecção de pontos estratégicos para a comunicação e para a transmissão de doenças. Novas métricas foram criadas e outras reformuladas, mas pouco tem sido feito para que se entenda a relação existente entre as diferentes medidas de centralidades, assim como sua relação com outras propriedades estruturais das redes em que elas são frequentemente aplicadas. Nossa pesquisa visa analisar e estudar essas relações para que sirvam de guia na aplicação das medidas de centralidade existentes em novos contextos e aplicações. Nós apresentamos também evidencias que indicam um desempenho superior das medidas conhecidas como Walk Betweenness, Information, Eigenvector and Betweenness na distinção de vértices das redes somente pelas suas características estruturais. Ainda, nós propiciamos detalhes sobre o desempenho distinto de cada métrica de acordo com o tipo de rede em que se trabalha. Adicionalmente, mostramos que várias das medidas de centralidade apresentam um alto nível de redundância e concordância entre si (com correlação superior a 0,8). Um forte indício que o uso simultâneo de várias métricas é improdutivo ou pouco eficaz. Os resultados da nossa pesquisa reforçam a ideia de que para usar apropriadamente as medidades de centralidade é de extrema importância que se saiba mais sobre o comportamento e propriedades das mesmas, fato que salientamos nessa dissertação. / Over the last years, centrality measures have gained importance within complex and social networks research, e.g., as predictors of behavior, identification of powerful and influential elements, detection of critical spots in communication networks and in transmission of diseases. New measures have been created and old ones reinvented, but few have been proposed to understand the relation among measures as well as between measures and other structural properties of the networks. Our research analyzes and studies these relations with the objective of providing a guide to the application of existing centrality measures for new environments and new purposes. We shall also present evidence that the measures known as Walk Betweenness, Information, Eigenvector and Betweenness are substantially better than other metrics in distinguishing vertices in a network by their structural properties. Furthermore, we provide evidence that each metric performs better with respect to distinct kinds of networks. In addition, we show that most metrics present a high level of redundancy (over 0.8 correlation) and its simultaneous use, in most cases, is fruitless. The results achieved in our research reinforce the idea that to use centrality measures properly, knowledge about their underlying properties and behavior is valuable, as we show in this dissertation.

A presente pesquisa foi elaborada a partir de um projeto prático, realizado no período entre 2010 e 2012. Desse modo, a reflexão que segue foi desenvolvida a partir dos procedimentos de trabalho, procurando identificar as recorrências, as referências, as escolhas, e suas consequentes implicações conceituais. O objeto de pesquisa compreende a troca de desejos por desenhos, feita através da internet e usando as redes sociais. Buscou-se aprofundar os importantes aspectos relacionais presentes nessa dinâmica, bem como aqueles relativos ao meio em que as trocas foram realizadas. A instauração e a articulação de três coleções distintas objetivou organizar os documentos de trabalho e as questões que concernem a apropriação, refletindo sobre como essas práticas se articulam e contribuem para a ampliação das possibilidades do trabalho criativo. / The herein presented research was elaborated based upon the practical work executed between the years of 2010 and 2012. The following reflection was developed from work procedures, trying to identify the recurrences, the references, the choices and its resulting conceptual implications. The object of research includes the exchange of desires for drawings, made through the internet and social networks. It searched to deepen the important relational aspects present in this dynamic, as well as aspects relating to the environment in which exchanges were made. The establishment and articulation of three distinct collections aimed to organize the working documents and the issues that concern appropriation, reflecting on how these practices work together and contribute to the expansion of creative possibilities.

A violência é um fenômeno sócio-histórico que acompanha a trajetória da humanidade, possui diferentes tipos e geralmente é identificada com dificuldade. Suas manifestações são inúmeras e atingem todos os domínios da vida social. Nesse aspecto, observamos a crescente preocupação com a violência escolar. A interação entre escola, família e comunidade, assim como a possibilidade de se estabelecer uma rede social, constitui-se em um fator relevante para a proteção e o desenvolvimento das habilidades sociais na infância e adolescência bem como para a efetiva atenção à violência no contexto escolar. Este estudo teve como objetivo identificar e analisar as redes sociais em torno das escolas de ensino médio pertencentes à rede estadual de Alfenas-MG para o enfrentamento dos casos de violência escolar. Trata-se de uma pesquisa descritiva, exploratória, de abordagem qualitativa. O campo de estudo foi composto por seis escolas urbanas públicas de ensino médio do município de Alfenas-MG e os sujeitos, nove supervisores pedagógicos das referidas escolas. Os instrumentos de coleta de dados foram o Mapa Mínimo da Rede Social Institucional e a entrevista semiestruturada. A análise dos dados ocorreu apoiada no referencial de Análise de Conteúdo, modalidade Temática, identificando os seguintes Núcleos Temáticos: A Escola e a Violência; Enfrentamento da Violência Escolar. O segundo Núcleo Temático teve como subtemas: Ações Internas e A Atuação em Rede. O fenômeno violência é compreendido com dificuldade e vários atos não são percebidos como violentos. As escolas aplicam advertência verbal ou escrita, comunicam pais ou responsáveis e entram em contato com Conselho Tutelar, Guarda Municipal e Promotoria Pública. No que se refere à atuação em rede, Conselho Tutelar, Promotoria Pública, Guarda Municipal, Prefeitura Municipal e universidades surgiram como apoio para o enfrentamento da violência escolar. Constatamos um número reduzido de vínculos e a fragilidade significativa entre aqueles existentes. Observamos a necessidade de estratégias voltadas à orientação de alunos, funcionários, famílias e comunidade para o enfrentamento das violências que ocorrem no âmbito escolar, sendo preciso o fortalecimento das redes sociais. / Violence is a social-historical phenomenon that accompanies the history of mankind, has different types and is generally difficulty to be identified. Its manifestations are numerous and affect all areas of life. In this regard, can be noted the growing concern on school violence. The interaction among school, family and community as well as the possibility of establishing a social network, constitutes a relevant factor in the protection and development of social skills in childhood and adolescence as well as for effective attention to violence in the school context. This study was aimed to identify and analyze social networks around the state high schools in Alfenas-MG in the dealing against cases of school violence. It is a descriptive research, exploratory, with qualitative approach. The field study consisted of six urban public schools in Alfenas-MG and the subjects were nine educational supervisors of those schools. The instruments for data collection were the Minimun Map of the Institutional Social Network and the semi-structured interview. The data analysis was supported in the frame of Content Analysis, Thematic modality, identifying the following Core Themes: The School and The Violence; Fight Against School Violence. The second Core Theme was divided in sub-themes: Internal Actions and Acting in Network. The phenomenon of violence is understood with difficulty and some actions are not perceived as violent. The schools conduct verbal or written warning, communicate the parents or guardians, come in contact with Child Protection Council, the Municipal Guard and the Public Prosecutor. Regarding the action in network, Child Protection Council, Public Prosecutor, Municipal Guard, City Hall and universities have emerged as support for the fight against school violence. Were found a small number of links and the significant weaknesses between those existing. It could be seen the need of strategies for orientation of students, staff, families and communities to confront the violence occurring in schools, requiring the strengthening of social networks.

M.Ed. (Educational Psychology) / With the increasing development of technology and the cyber world, a culture of social networking has been established. Social networking sites, such as Facebook™, became useful and popular tools, specifically for young adolescents, as it offers engaging opportunities to connect, communicate and interact with peers while enabling and sustaining interpersonal relationships. Given the stage of development in which they reside according to Erikson, adolescents place immense value on their social activity and connectedness, and therefore a positive self-identity and self-esteem becomes dependent on their social success. This study attempted to explore the possible psychosocial effects, specifically on the self-esteem of adolescents, who regularly interact on Facebook™. The research was conducted at an urban public school in the northern suburbs of Johannesburg. Participants for the individual interviews were selected based on how thoroughly they completed their questionnaires which I requested of this grade 10 group. From the analysis of the data, four main categories emerged namely; positive and negative influences on self-esteem, deception on Facebook™, crystallisation of identity and dangers associated with Facebook™. Consistent with recent literature regarding social networking and its effects, the results suggested that there is a definite link between Facebook™ interaction and self-esteem and that the social interactions on Facebook™ can have both positive and negative effects on the self-esteem of the individual. It is however crucial to consider the dangers and detrimental effects on both the self-esteem and the safety of individuals. Furthermore interesting features that were illuminated by the research is the concept of deception on social networking sites and individuals’ tendency to deceive and mislead based on a desire to be accepted and to avoid criticism. Lastly the idea of individuals’ identity being crystallised through their social interaction on Facebook™ came through strongly. Recommendations made based on the findings include adapting the Life-Orientation curriculum to address social etiquette and moral guidelines pertaining to online behaviour and interactions. Recommendations for future research include, amongst others, broadening the context and exploring this issue throughout the whole of South Africa and to observe differences between urban and rural areas.

It is commonly held in the literature that users find security and privacy difficult to comprehend. It is also acknowledged that most end-user applications and websites have built-in security and privacy features. Users are expected to interact with these in order to protect their personal information. However, security is generally a secondary goal for users. Considering the complexity associated with security in combination with the notion that it is not users’ primary task, it makes sense that users tend to ignore their security responsibilities. As a result, they make poor security-related decisions and, consequently, their personal information is at risk. Usable Security is the field that investigates these types of issue, focusing on the design of security and privacy features that are usable. In order to understand and appreciate the complexities that exist in the field of Usable Security, the research fields of Human-Computer Interaction and Information Security should be examined. Accordingly, the Information Security field is concerned with all aspects pertaining to the security and privacy of information, while the field of Human-Computer Interaction is concerned with the design, evaluation and implementation of interactive computing systems for human use. This research delivers a framework to evaluate Usable Security in online social networks. In this study, online social networks that are particular to the health domain were used as a case study and contributed to the development of a framework consisting of three components: a process, a validation tool and a Usable Security heuristic evaluation. There is no existing qualitative process that describes how one would develop and validate a heuristic evaluation. In this regard a heuristic evaluation is a usability inspection method that is used to evaluate the design of an interface for any usability violations in the field of Human-Computer Interaction. Therefore, firstly, a new process and a validation tool were required to be developed. Once this had been achieved, the process could then be followed to develop a new heuristic evaluation that is specific to Usable Security. In order to assess the validity of a new heuristic evaluation a validation tool is used. The development of tools that can improve the design of security and privacy features on end-user applications and websites in terms of their usability is critical, as this will ensure that the intended users experience them as usable and can utilise them effectively. The framework for evaluating Usable Security contributes to this objective in the context of online social networks.