The U.S. food system is afflicted by a variety of social, ecological, and economic predicaments including hunger, food access inequalities, soil and water degradation, and lack of community control over food. Scholars and activists agree that in order for U.S. food movement actors to affect significant system-wide change, players must bridge a multitude of issue areas and ideological differences. Despite thorough analyses of local and regional food systems, little research has been conducted on either national level advocacy perspectives or the ties that bind and divide food advocacy coalitions. This dissertation's central research question examines how the U.S food advocacy movement works to resist the hegemonic domination of the national food system by state and corporate actors. To answer this question, this project develops a social network analysis of 71 national-level food advocacy actors, compiles web-based issue and tax data, and conducts 36 semi-structured interviews with senior food activist staff. Social movement literature and Antonio Gramsci's concepts of counter-hegemonic movements and wars of position inform the findings and reveal the national food movement's nascent propensity to unite cultural and class struggles to create significant pressure for systematic change in the U.S. food system. Additionally, this research tests existing theoretical work related to the food advocacy network and distinctions between interest group and social movement type organizations. This dissertation reveals that despite most activists' conviction that a constellation of agri-business and state policies dominate the U.S. food system, significant network rifts, framing dilemmas, strategic conflicts, and resource complexities prevent national food activists from generating a robust challenge to hegemonic food system actors.

The current research identifies the impact of sharing day-to-day information in social network sites (SNS) on the relationships we hold within and outside of them. Stemming from the literature on self-disclosure, uncertainty reduction, personal relationships, privacy and computer-mediated communication (CMC), a concurrent triangulation research strategy is adopted to identify the patterns of relationship development and interaction in SNS. Using a mixed methods approach, five studies were conducted to determine how young adults interact via SNS. Empirical findings suggest SNS users are driven by the need to reduce uncertainty and gather information about their interaction partners. An interaction between several factors was found to impact on relationships between communication partners: the frequency of information sharing; the content of the shared information; the type of relationship held between the sender and recipient; the stage of relationship development; the medium of communication, and; an expected social contract. A conceptual model of interpersonal interaction within SNS environments is proposed, identifying the links between sharing, certainty and relationship quality, and manifested communication behaviour throughout relationship development. Implications for the fields of communication science, CMC, and social and behavioural psychology are discussed.

Users of social networking services such as Facebook often want to manage the sharing of information and content with different groups of people based on their differing relationships. The growing popularity of such services has meant that users are increasingly faced with the copresence of different groups associated with different aspects of their lives, within their network of contacts. However, few users are utilising the group-based privacy controls provided to them by the SNS provider. In this thesis we examine the reasons behind the lack of use of group-based privacy controls, finding that it can be largely attributed to the significant burden associated with group configuration. We aim to overcome this burden by developing automated mechanisms to assist users with many aspects of group-based privacy control, including initial group configuration, labeling, adjustment and selection of groups for sharing privacy sensitive content. We use a mixed methods approach in order to understand: how automated mechanisms should be designed in order to support users with their privacy control, how well these mechanisms can be expected to work, what the limitations are, and how such mechanisms affect users’ experiences with social networking services and content sharing. Our results reveal the criteria that SNS users employ in order to configure their groups for privacy control and illustrate that off-the-shelf algorithms and techniques which are analogous to these criteria can be used to support users. We show that structural network clustering algorithms provide benefits for initial group configuration and that clustering threshold adjustments and detection of hubs and outliers with the network are necessary for group adjustment. We demonstrate that public profile data can be extracted from the network in order to help users to comprehend their groups, and that contextual information relating to context, contacts, and content can be used to make recommendations about which groups might be useful for disclosure in a given situation. We also show that all of these mechanisms can be used to significantly reduce the burden of privacy control and that users react positively to such features.

Chat rooms are of enormous interest to social network researchers as they are one of the most interactive internet areas. To understand the behaviour of users in a chat room, there have been studies on the analysis of the Response Waiting Time (RWT) based on traditional approaches of aggregating the network contacts. However, real social networks are dynamic and properties such as RWT change over time. Unfortunately, the traditional approach focuses only on static network and neglecting the temporal variation in RWT which may have lead to misrepresentation of the true nature of RWT. In order to determine the true nature of RWT, we analyse and compare the RWT of three online chat room logs (Walford, IRC and T-REX) putting into consideration the dynamic nature of RWT. Our research shows that the distribution of the RWT exhibits multi-scaling behaviour, which signi cantly a ects the current views on the nature of RWT. This is a shift from simple power-law distribution to a more complex pattern. The previous study on users RWT between pairs of people claims that the RWT has a power-law distribution with an exponent of 1. However, our research shows that multi-scaling behaviour and the exponent has a wider range of values which depend on the environment and time of day. The di erent exponents observed on di erent time scales suggest that the time context or environment has a signi cant in uence on users RWT. Furthermore, using the chat characterise, we predicted the factors which could minimize response waiting time and improving the friendship connection during online chat sessions. We apply our ndings to design an algorithm for chat thread detection. Here, we proposed two variations of cluster algorithm. The rst algorithm involves the traditional approach while in the second one, the temporal variations in RWT was taken into consideration to capture the dynamic nature of a text stream. An advantage of our proposed method over the previous models is that previous models have involved highly computationally intensive methods and often lead to deterioration in the accuracy of the result whereas our proposed approach uses a simple and effective sequential thread detection method, which is less computationally intensive.

Em um ambiente corporativo, depois de algum tempo, as pessoas sabem a quem recorrer quando necessitam de ajuda ou de algum conhecimento que não dispõem, caracterizando um contexto de múltiplas influências entre pessoas ou redes de relacionamentos. Desta forma, o trabalho proposto, teve como objetivo identificar os atores da rede de relacionamentos, que exercem maior influência no comportamento de segurança. Para isso, fomos buscar na literatura estudos de abordagens teóricas e práticas, que utilizassem conceitos sócio-antropológicos, de preferência trabalhos com enfoque na área nuclear, que possuíssem questionários de cultura de segurança, devidamente testados e avaliados por métodos estatísticos. Como resultado, identificamos inúmeros atributos que podem caracterizar uma cultura de segurança positiva e, extraímos quatro daqueles que mais apareciam nos diversos estudos. A partir daí, concebemos as questões que nos possibilitassem mapear e entender as redes sociais que influenciam sobre a formação e manutenção destas características. Então, aplicamos nossa pesquisa no âmbito do IPEN-CNEN-SP, no qual utilizamos a técnica de pesquisa tipo bola de neve para mapeamento das redes sociais de compartilhamento de idéias, bem como aplicamos também o questionário para mapear as crenças dos atores com significativo grau de influência (obtido a partir do levantamento de redes de influências). Embasado em técnicas de análise de redes sociais, obtivemos subsídios para comprovação de que as redes dos atores mais influentes são relevantes na formação de cultura de segurança do IPEN-CNEN-SP. / In a corporative environment, after a while, people know to whom to turn to when they require help or some knowledge non available at their disposal, characterizing a context of multiple influences among people or relationship network. This way, the proposed work had as objective to identify actors, from relationship network that exerts a higher influence in safety behavior. For this, we researched in the literature studies on theoretical and practical approaches, which would use social-anthropological concepts, especially works with approach in nuclear area, provided with questionnaires on safety culture, strictly tested and assessed via statistical methods. This resulted in the identification of a lot of attributes able to characterize a positive safety culture and from them extracting four of the most shown in various studies. From now on, there were conceived questions for making viable the mapping out and the understanding of social network responsible for influencing the building-up and the maintenance of these characteristics. So, it was applied in our research, within IPEN-CNEN-SP extent, the snowball type as research technique, for the mapping out of social network toward ideas sharing, as well it was applied the questionnaire intended for mapping out actors believes with a significant influence degree (obtained from influences network survey). Based in social network analyses techniques, we obtained subsides for proving that network from actors the most influent are relevant for the building-up of IPEN-CNEN-SP safety culture.

Em um ambiente corporativo, depois de algum tempo, as pessoas sabem a quem recorrer quando necessitam de ajuda ou de algum conhecimento que não dispõem, caracterizando um contexto de múltiplas influências entre pessoas ou redes de relacionamentos. Desta forma, o trabalho proposto, teve como objetivo identificar os atores da rede de relacionamentos, que exercem maior influência no comportamento de segurança. Para isso, fomos buscar na literatura estudos de abordagens teóricas e práticas, que utilizassem conceitos sócio-antropológicos, de preferência trabalhos com enfoque na área nuclear, que possuíssem questionários de cultura de segurança, devidamente testados e avaliados por métodos estatísticos. Como resultado, identificamos inúmeros atributos que podem caracterizar uma cultura de segurança positiva e, extraímos quatro daqueles que mais apareciam nos diversos estudos. A partir daí, concebemos as questões que nos possibilitassem mapear e entender as redes sociais que influenciam sobre a formação e manutenção destas características. Então, aplicamos nossa pesquisa no âmbito do IPEN-CNEN-SP, no qual utilizamos a técnica de pesquisa tipo bola de neve para mapeamento das redes sociais de compartilhamento de idéias, bem como aplicamos também o questionário para mapear as crenças dos atores com significativo grau de influência (obtido a partir do levantamento de redes de influências). Embasado em técnicas de análise de redes sociais, obtivemos subsídios para comprovação de que as redes dos atores mais influentes são relevantes na formação de cultura de segurança do IPEN-CNEN-SP. / In a corporative environment, after a while, people know to whom to turn to when they require help or some knowledge non available at their disposal, characterizing a context of multiple influences among people or relationship network. This way, the proposed work had as objective to identify actors, from relationship network that exerts a higher influence in safety behavior. For this, we researched in the literature studies on theoretical and practical approaches, which would use social-anthropological concepts, especially works with approach in nuclear area, provided with questionnaires on safety culture, strictly tested and assessed via statistical methods. This resulted in the identification of a lot of attributes able to characterize a positive safety culture and from them extracting four of the most shown in various studies. From now on, there were conceived questions for making viable the mapping out and the understanding of social network responsible for influencing the building-up and the maintenance of these characteristics. So, it was applied in our research, within IPEN-CNEN-SP extent, the snowball type as research technique, for the mapping out of social network toward ideas sharing, as well it was applied the questionnaire intended for mapping out actors believes with a significant influence degree (obtained from influences network survey). Based in social network analyses techniques, we obtained subsides for proving that network from actors the most influent are relevant for the building-up of IPEN-CNEN-SP safety culture.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Background: The purpose of this study was to determine the association between social media dependence and depressive symptoms and also, to characterize the level of dependence. It was a transversal, analytical research. Subjects and Methods: The stratified sample was 212 students from a private university that used Facebook, Instagram and/or Twitter. To measure depressive symptoms, Beck Depression Inventory was used, and to measure the dependence to social media, the Social Media Addiction Test was used, adapted from the Internet Addiction Test of Echeburúa. The collected data were subjected for analysis by descriptive statistics where STATA12 was used. Results: The results show that there is an association between social media dependence and depressive symptoms (PR [Prevalence Ratio] = 2.87, CI [Confidence Interval] 2.03–4.07). It was also shown that preferring the use of Twitter (PR = 1.84, CI 1.21–2.82) over Instagram (PR = 1.61, CI 1.13–2.28) is associated with depressive symptoms when compared to the use of Facebook. Conclusion: Excessive social media use is associated with depressive symptoms in university students, being more prominent in those who prefer the use of Twitter over Facebook and Instagram. / Revisión por pares

Team norms are one of the most frequently used explanations of how teams as a collective entity can influence individual member’s behaviors (Hackman & Walton, 1986; Bettenhausen & Murnighan, 1991; Feldman, 1984). Despite such importance, current theoretical and empirical development of team norms is relatively inadequate. In this dissertation, I view norm strength and norm enforcement as two central pillars of team norms, and specifically examine team norm enforcement from a social network perspective. I first develop a typology based on the existing literature and specify the behavior content of three types of norm enforcement mechanisms: sanction, recognition and learning. Second, I examine the impact of the structural and configural properties on team performance. This model was tested on 799 employees nested in 101 work teams from China. Results from the data analysis have offered partial support that the structural characteristics of norm enforcement network had impacts on team performance above and beyond norm strength.

My research examines the importance of a particular form of cross-group brokerage in social networks wherein a person represents a bridge between his or her group and people belonging to a different group. Prior research on network brokerage and leadership emergence has failed to distinguish between brokerage in general and the kind of boundary-spanning between groups that is the focus of my research. Moreover, what we currently know about social network brokerage and leadership emergence comes either from highly abstracted laboratory-based work, or it comes research in relatively traditional work organizations with clear formal structures. It is unclear whether prior research from traditional organizational settings can be applied to nontraditional organizations in the so-called “creative industries,” which are the focus of my research. The core hypotheses my research examines are: (1) Do individuals whose friendship networks help them bridge between groups emerge as leaders in the eyes of others? And (2) Are people who are socially perceptive and socially skilled better at leveraging such boundary-spanning positions to win nominations of leadership from others? Data from the study come from interview and survey data from four different musical orchestras based in Korea.

Professional burnout refers to the development of negative emotions, cynical thoughts, and physical and mental exhaustion as a response to stressors associated with one’s career. Within the teaching profession, professional burnout has been associated with an increase in teacher attrition. In an effort to promote a positive school environment where teachers feel supported and committed to the profession, many administrators have implemented structured collaborative opportunities within their buildings. While personal relationships within the school network can provide a mitigating effect against professional burnout, the possibility exists that teacher leaders can be overcentralized and negatively impacted by the maintained relationships. By potentially forcing centralization on critical team members and emphasizing them as the “go-to” person for collaboration, schools may be inadvertently putting their best at risk for burnout. Using a mixed-methods design, the following study investigates the perceived benefits and constraints of centrality within the school network on reported burnout. The social networks at four elementary schools were analyzed to determine the level of connectivity for each certified staff member. Participants were asked to identify the colleagues with whom they collaborate. Using Social Network Analysis, the level of centrality (as measured by number of network connections both received and directed) was calculated for each participant based on number of network ties both received and directed. Centrality scores were included with previously identified variables associated with teacher burnout including level of perceived stress, perception of school environment, principal support, and other demographic data in a series of hypothesis tests to assess the relationship between network connectivity and reported burnout. A series of semi-structured interviews were conducted with a selection of participants to further explore the impact of network connections on participant burnout. The results of this exploratory study found that not all collegial relationships are beneficial. A significant positive relationship between number of collaborative ties directed toward a teacher and their depersonalization score on the Maslach Burnout Inventory was identified, indicating that individuals who are frequently identified as a collaborator report higher burnout. The findings from this study produce a unique perspective on collaboration within the school network. As has been reported previously, level of connectivity within the school network as measured by the number of teachers one can identify as collaborators appears to mitigate (or not significantly increase) a teacher’s risk of professional burnout. However, being identified as a collaborator by a large number of teachers (in-degree) significantly increases one’s risk for depersonalization behaviors.