The new social media sites - blogs, micro-blogs, and social networking sites, among others - are gaining considerable momentum to facilitate collaboration and social interactions in general. These sites provide a tremendous asset for understanding social phenomena by providing a wide availability of novel data sources. Recent estimates suggest that social media sites are responsible for as much as one third of new Web content, in the forms of social networks, comments, trackbacks, advertisements, tags, etc. One critical and immediate challenge facing the MIS researchers then becomes - how to effectively utilize this huge wealth of social media data, to facilitate business knowledge discovery and decision making.Among these available data sources, social networks constitute the backbone of almost all social media sites. These network structures provide a rich description of the social scenes and contexts, which is helpful for us to address the above challenge. In this dissertation, I have primarily employed the probabilistic network models, to study various social network related problems arose from the use of social media services. In Chapter 2 and Chapter 3, I studied how information overload can affect the efficiency of information diffusion in online social networks (Delicious.com and Digg.com). Novel diffusion model were proposed to model the observed information overload. The models and their extensions are thoroughly evaluated by solving the Influence Maximization problem related to information diffusion and viral marketing applications. In Chapter 4, I studied the information overload in a micro-blogging application (Twitter.com) using a design science methodology. A content recommendation framework was proposed to help micro-blogging users to efficiently identify quality emergency news feeds. Chapter 5 presents a novel burst detection algorithm concerning identifying and analyzing correlated burst patterns by considering multiple inputs (data streams) that co-evolve over time. The algorithm was later used for discovering burst keywords/tag pairs from online social communities, which are strong indicators of emerging or changing user interests.Chapter 6 concludes this dissertation by highlighting major research contributions and future directions.

This case study examined the spread of ideas in a Gr. 5/6 classroom in which the teacher was attempting to foster a knowledge building community. The goal of the research was to explore the relationship between the social network of the classroom (in terms of face-to-face and computer-mediated interactions), the teacher’s role, and the spread of ideas. Further, the thesis examined how social network tools may help teachers better understand the pedagogical implications of Scardamalia and Bereiter’s (1991) Teacher A, B, C models. Analyses of videotaped lessons revealed the teacher used a complex mix of traditional instructional methods and knowledge building strategies while trying to shift the locus of control of learning to students. Critical teacher-driven processes included the class-wide adoption of knowledge building vocabulary and practices, and efforts to foster higher levels of student-student discourse. Analyses of online interactions provided strong evidence of highly interconnected student-student online networks, with the note reading network being especially dense. Longitudinal studies revealed these network established themselves early in the unit, and persisted during the course of the inquiry. There was evidence that idea improvement was present in addition to idea spread. In face-to-face classroom communication, the teacher’s role was more central, particularly in "Knowledge Building Talk" sessions. However, here too, the teacher made efforts to shift the locus of control. Overall the analyses suggest that social network tools are potentially useful for helping teachers make the difficult transition from "Teacher A" and "Teacher B" strategies, in which the locus of control is with the teacher, to "Teacher C" strategies, in which strategic cognitive processes are turned over to students. This dissertation proposes that movement toward Teacher C practices may be illustrated, in part, by a shift in classroom network topologies from that of a star-shaped network, centered on the teacher, to a highly interconnected student-student network. Finally, the thesis recounts a number of ways in which the use of social network tools uncovered discourse patterns of which the teacher was unaware, including gender differences in reading, building-on, and contribution patterns.

The mechanisms and functions of shark grouping behaviour have received relatively little scientific attention to date. The current widespread use of social network analysis to study animal groups, in concert with rapid advances in animal tracking technology, now allows us to test specific hypotheses about how and why sharks form groups. This thesis uses replicated laboratory experiments to investigate some of the mechanisms underpinning aggregation in a model species of benthic, oviporous elasmobranch, the small spotted catshark (Scyliorhinus canicula L. 1758; Scyliorhinidae). Acoustic tracking of this species in the wild is also conducted to explore how network analyses can be adopted to study the localized movements, habitat connectivity and ranging behaviour of adult sharks. Groups of juvenile S. canicula were characterized by non-random social preferences, crucially, only when individuals were familiar with one another suggesting social recognition is important in young sharks of this species. Genetic analyses of parent and offspring DNA revealed very high levels of multiple paternity in this species, likely due to male sexual harassment and multiple mating, which leads to increased genetic diversity between juvenile sharks. Perhaps unsurprisingly, there was no evidence of kin relatedness structuring social interactions between conspecifics. Furthermore, testing the effects of environment on social behaviour provided evidence that these juveniles aggregated more in structurally complex environments than simple ones. However, at the individual level sharks showed consistency in their social network positions through time and across different habitat types. This result is indicative of personality traits in S. canicula. Using data gathered via passive acoustic telemetry of wild shark behaviour, network analysis provided a useful tool with which to quantify movement between receivers. One chapter has been dedicated to the application of these methods, highlighting a number of different analyses for predicting movement behaviour from such data. Finally, these methods were adopted to address ecological questions in this sexually segregated species. Persistent site fidelity to a localised inshore area by both male and female sharks suggested that segregation occurred at a relatively small spatial and temporal scale. Despite strong evidence of segregation, analyses of movement networks and individual co-occurrences revealed distinct periods of behavioural synchronicity during the months of March, April and May. In addition, habitat complexity appeared to be a significant driver of female behavioural strategy. Enhancing our knowledge of the social and environmental drivers of aggregation and movement in sharks is of great importance given the ecological threat facing many of our ocean’s top elasmobranch predators.

People always find themselves interacting with others and forming ties with them; these ties shape an individual’s social network which helps form the self-conception and identity of a person. In discussing the essence of social networks and how they are formed the concept of homophily is of high significance. Therefore, the purpose of this research is to show the association between homophily and the process of friendship formation. As the structure of any social network is important in tie formation, I have also intended to study homophilous tie formation from a distinctiveness theory perspective, suggesting that individuals with minority characteristics are more prone to form friendship ties with each other. The types of homophily studied in this research are gender, religion, nationality/ethnicity, and political views. The data is gathered from the cohort which started grade 10 in upper secondary education in a school in Stockholm in Autumn 2012. The analyses were conducted using logistic regression. The results indicated the existence of gender homophily and national homophily. However, religious homophily did not appear to be significant; political homophily was only significant for individuals who were participating in political meetings. However, due to lack of sufficient data, the relations between network structure and homophilous relations could not be accurately tested. Since the data were not collected randomly and the school was chosen due to its specific characteristics, it is not possible to generalize the results of the research to all of the adolescents living in Stockholm. However, this research sheds some light on the mechanisms at play in friendship formation among adolescents.

The study of social networks has become well established in social science. As part of this development, the past several decades have seen an increasing interest in adolescent social relations. Some of the relevant research has focused on explaining similarity patterns in friendship with respect to social categories and have found homophily (the tendency to select similar friends) to be an important factor, or mechanism, influencing friendships. Although the study of social networks has also documented the importance of several other factors for the formation/maintenance of friendships, it has paid little attention to how different factors might interact. Surprisingly little attention has also been paid to how culturally constructed desires and beliefs might influence friend selection. Focusing on social categories relating to immigration background and religiosity, this research examines how homophily interacts with, or is affected by, a school’s classroom organization, and whether students’ beliefs and desires influence the formation and maintenance of friendships. Specifically, the four studies that constitute the second part of this work examine (1) whether native/immigrant background homophily varies depending on whether ties are formed/maintained within or across classroom boundaries, (2) whether adolescents tend to select friends with similar preferences for cultural diversity, and whether reporting a stronger preference for cultural diversity is associated with i) having more friends in school and ii) being more inclined to select dissimilar friends with respect to parents’ birth region, (3) whether adolescents tend to select similar friends in terms of religiosity (defined as the importance attributed to religion), and whether adolescents are influenced by the religiosity of their friends, and finally (4) whether selection of friends with similar beliefs brings with it similarity among friends in terms of behaviors such as alcohol consumption and cigarette smoking. All four studies are based on three observations of the complete friendship network of a cohort of adolescents during the first year in upper secondary education (N=115) and statistical models for social network analysis, so-called stochastic actor-oriented models. The results suggest adolescents’ inclination to select similar friends in terms of social categories varies with a school’s classroom structure and (for a smaller number of students) diversity preferences. Diversity preferences are also found to play a role in friend selection processes in other ways. In addition, so is religiously. Friend selection based on similarity in religiosity is found to lead to similarity among friends with respect to drinking behaviors. These findings suggest that considering the interplay between different tie formation mechanisms as well as individual desires and beliefs can be important for better understanding the evolution of social networks. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Submitted. Paper 2: Submitted. Paper 3: Submitted. Paper 4: Submitted.</p><p> </p>

SNA provides a wide range of tools that allow examination of telecommunications graphs. Those graphs contain vertices representing cell phone users and lines standing for established connections. Many sna tools do not incorporate the intensity of interaction. This may lead to wrong conclusions because the difference between best friends and random contacts can be defined by the accumulated duration of talks. To solve this problem, we propose a closeness centrality measure (ewc) that incorporates line values and compare it to Freeman's closeness. Small exemplary networks will demonstrate the characteristics of the weighted closeness compared to other centrality measures. Finally, the ewc will be tested on a real-world telecommunications graph provided by a large Austrian mobile service provider and the advantages of the ewc will be discussed. / Series: Research Report Series / Department of Statistics and Mathematics

In Social Network Analysis (SNA) centrality measures focus on activity (degree), information access (betweenness), distance to all the nodes (closeness), or popularity (pagerank). We introduce a new measure quantifying the distance of nodes to the network center. It is called weighted distance to nearest center (WDNC) and it is based on edge-weighted closeness (EWC), a weighted version of closeness. It combines elements of weighted centrality as well as clustering. The WDNC will be tested on two e-mail networks of the R community, one of the most important open source programs for statistical computing and graphics. We will find that there is a relationship between the WDNC and the formal organization of the R community. / Series: Research Report Series / Department of Statistics and Mathematics

The sociotechnical system of print-on-paper for the dissemination of textual information prevails despite widespread concerns about its sustainability. On the basis of sociotechnical transitions theory the print-on-paper system is perceived as a regime. Information technology is identified as one of the generic technologies that has the potential to address the unsustainability of the incumbent regime. Its potential effects are examined through the development of the electronic book, which is defined as those IT applications providing an alternative form of textual display to printed paper. Yet, such applications have remained marginal. According to sociotechnical transitions theory the electronic book can be seen as a niche in relation to the print-on-paper regime. An alternative conceptualisation of transitions as a process of network reconfiguration is suggested. On that basis, the electronic book is depicted as a number of emergent innovation networks. Social Network Analysis methods informed by network approaches to innovation theory are applied to visualise and discuss these emergent networks. In one of the representations, the electronic book is mapped as a sociotechnical network including organisations, users and technologies. It emerges that network formation often transgresses a distinct niche-regime divide. Patterns of network interaction are explored and assessed as to whether they represent a sociotechnical transition in progress. The analysis reveals different patterns of network formation which are indicative of prospective sociotechnical trajectories where different concepts of the electronic book are emphasised. It emerges that the discussion of sustainability and the emergence of the electronic book remain largely unlinked.

This thesis tests Robert S. Weiss's 1973 theory of loneliness, which claims two types of loneliness: emotional and social. Emotional loneliness is the affective reaction to the absence of a close attachment bond. Social loneliness stems from inadequate integration into a social network. Undergraduate residents of a university dormitory completed questionnaires on loneliness, attachment, personality, and relationships with other dorm residents. Patterns of relational ties among participants were evaluated using social network analysis, specifically density, tie strength, and four forms of centrality. Results reveal that, while controlling for neuroticism, the network measure of outdegree and the two attachment dimensions accounted for more than half the variance in loneliness, R = .73. None of the three predictors intercorrelated significantly. A portion of loneliness is derived from one's internal attachment security and a separate portion is derived from the external features of one's social network integration.

Jana Hoferková - Copyright protection on social networks Resume The purpose of this thesis is to analyse the subject of copyright protection on social networks. The thesis is composed of five chapters, each of them dealing with different aspects of the topic discussed. Chapter One is introductory and explains the reasons behind focusing on this issue. Chapter Two provides a brief description of social networks. It consists of two parts, which discuss possible legal threads of social networks. Part One focuses on problem of privacy protection whereas Part Two deals with the issue of data protection on social networks. Chapter Three provides an overview of copyright on social networks. It is subdivided into four parts, each of them dealing with different aspects of copyright in relation to social networks. Part One describes the copyright itself in the Czech legal system. Part Two compares the Czech copyright with the Anglo-American copyright, for its relevance to social networks. Part Three examines the question of the governing law, as the relationship between social network and user includes an international aspect. Part Four investigates the license agreement between social network and user. Finally, Chapter Four concentrates on the liability for copyright infringement on social networks. Five Parts of...