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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Modeling information diffusion in social networks

Sun, Hongxian., 孙鸿賢. January 2012 (has links)
Interpersonal communication with network infrastructure creates mobile and online social networks, which shorten the distance among people. It naturally leads to an important question asking for a clear and detailed description of information dissemination and diffusion process in social networks. An in-depth understanding of the question may help in various aspects,e.g., designing better communication protocols and predicting the demand of hot contents. In the thesis we focus on two concrete sub-questions. The first one is to describe the performance of mobile social networks under the practical constraint that information is only allowed to be shared among mutual social friends. Existing designs for mobile social networks enable opportunistic message exchange whenever two mobile devices are within the transmission range of each other. However in real life, people may only be willing to interact with their social friends instead of anyone upon contact. Under such a constraint message forwarding may behave differently. We concentrate on modeling the end-end delivery delay in this scenario under two message validity models, unlimited validity and limited validity. In the first case nodes try their best to relay a message to the destination. While in the latter case a relay node will delete its local copy of a message after carrying it for some time T. Mean-field equations for the dynamic of the population of spreader nodes are derived. With solutions of these equations and empirical studies, we get insightful results. First, more skewed distribution of the number of friends leads to larger delay. Second, the unicast delay is almost constant rather than quickly decreasing with the network size. Last, with a moderate choice of T, we can guarantee almost 100% delivery with a delay very close to the case of unlimited validity. It signifies that a good trade-off can be obtained between delivery efficiency and energy/storage overhead. The second sub-question asks for a model of information diffusion in online social networks. Sharing information in OSN platforms like Twitter and Facebook has become an important part of human life. Thus understanding the dynamic is important as it may help, for example, predict the demand of media contents. We make use of the age-dependent branching process framework to describe the diffusion of content with constant popularity. We give explicit expression for the expected diffusion cascade size, analyze its asymptotic behavior and compare it with the prediction of traditional, over-simplified epidemic model. Also we analyze the diffusion of content with time-variant popularity. An integral equation governing the growth of cascade size is given. Some measurement observations are also explained and quantified. Lastly we design a new model incorporating the geographical locality of contents based on the study of multitype age-dependent branching processes, where the expression for expected cascade size is also given, offering a clear picture of the whole process. Extensive simulations verify the analytical expressions and offer straightforward insights into some other properties of the diffusion process which are not captured by the mathematical formulation. / published_or_final_version / Computer Science / Master / Master of Philosophy

Stable Nash networks with production

Postalci, Mustafa Efe January 2003 (has links)
This dissertation studies how and in what forms the relationships between the agents in a society shape. We provide four models to examine the outcomes of the non-cooperative network formation game where agents engage in two activities: forming links and producing output. We show that when a link between two agents allows only the forming agent to enjoy the output of the other, a society always admits a stable network. Furthermore, this network almost always has a center-periphery structure. Such societies consist of two types of agents, centers that are directly connected by every other agent and peripheries to whom no agent connects. We also find that centers produce more output and typically have lower payoff than peripheries. When a link allows both agents to enjoy the output of each other, a society does not always admit a stable network. In societies where agents enjoy the outputs of those that are also indirectly linked, stable networks can take much richer forms. In this setup stable networks include the center-periphery networks as well as the wheel and star networks. If agents can adjust the efficiency of their links, then every society admits a stable network which always has a center-periphery structure. / Our results for all four models show that the level of production in non-empty stable networks is less than the amount that will maximize the total benefits in the society.

Technological distractions : the impact of social networking sites use on the academic performance of students at the University of Limpopo

Koma, Thato Serotho January 2016 (has links)
Thesis (M.A. (Media studies)) --University of Limpopo, 2016. / Students today are surrounded by vast amounts of technological gadgets that enable communication with friends very easy. Social networking sites, social media and internet have become part of the lives of the students today and the means to their social happiness. This is emphasised by the growing concern over the use of these social networking sites and a growing fear that these sites might actually be causing much damage to the fundamental learning abilities of these students. The purpose of this study was to investigate the impact of the use social networking sites among the students of the University of Limpopo. Qualitative and quantitative research methods were used in this study to explore the traits of the use of social networking sites from the perspective of the students and the lecturers. The data was collected using survey with structured questionnaires for the students and the face-to-face interview with the lecturers to explore their perception over the use of social networking sites. A total of three hundred and nineteen (319) questionnaires were distributed randomly among the students of University of Limpopo and the researcher received two hundred and ninety seven (297) filled questionnaires. Four face-to-face interviews were carried out at the offices of the lecturers that participated in the study. The study revealed that the social networking site Facebook is used more among students and that cell-phones are their means of accessing the internet and social networking sites. The lecturers however pointed out that there is a need for concern with the constant availability of technology at the reach of these students. However, there is a gradual positive development as the students are becoming more and more self-aware that their use of these sites has portends a negative impact on their academic performance. While there are very remote incidents of text language in academic writing contrary to the students’ perception, the lectures believe that student writing quality exists and that what is often perceived as social networking sites language turns out to be innocent spelling errors. Key words Social networking sites, technology, procrastination, distraction, academic performance

Crisis at the Finish Line: A Thematic Analysis of Instructing Information via Twitter

Rudolph, Sadie Rae January 2014 (has links)
This study expands current crisis communication research by exploring the communication of instructing information via Twitter. Drawing from the internalization, explanation, and action components of Sellnow & Sellnow's (2013) IDEA Model, this study analyzes live tweets posted by the Boston Police Department during the 2013 Boston Marathon bombing crisis. Examining Tweets posted during a crisis allows us to better understand what constitutes useful, valuable instructing information that can be communicated via social media in real time. Further, scholars have just begun exploring social media's implications for crisis communication. This study extends the IDEA Model to reach crisis communication and social media. Findings also indicate the three components of the IDEA Model are valuable topics to consider when communicating instructing information via Twitter. Finally, we learn that Twitter's 140 character limit does not impede the social media platform as a vehicle to communicate instructing information during a crisis.

Stable Nash networks with production

Postalci, Mustafa Efe January 2003 (has links)
No description available.

Trust in a decentralised mobile social network

Markides, Bradley Michael 31 August 2011 (has links)
M.Sc. / Social networks are evolving as mobile devices are able to establish direct communication with each other. The success of social networking sites such as FaceBook is prompting mobile phone vendors and operators to focus on providing a real human experience, as the presence of others who are in close proximity can be detected, enabling the formation of real as opposed to virtual friendships. Mobile devices are considered to be the next logical step in social networking, as they become more pervasive. Mobile social networking is a new movement in social networking, as people have membership of both a virtual community through an online social network environment, and a physical community where they are located. This research has the aim of extending the social networking experience between the virtual and physical worlds, to allow people to form real relationships with each other by using concepts from the virtual world. A move in mobile social networking is the decentralised exploration of friendships. Short-range wireless protocols like Bluetooth enable collaborative applications between mobile devices of users. Unlike conventional centralised social networks that rely upon a central authority to organise the opinions of each member of the social network and protect their personal information, members of a decentralised network are completely autonomous and responsible for their own individual behaviour. When people meet for the first time, they thus need help to determine if they can trust each other. The dissertation presents BlueTrust, a trust model for use in decentralised mobile social networks. The BlueFOAF prototype application demonstrates the operation of the BlueTrust mechanism. This application investigates the underlying technologies researched, as well as the implementation of BlueTrust to determine how others who are in close proximity can be trusted. It focuses on establishing trust between users by computing trust levels to support face-to-face user interaction.

A study of the social support construct with a group of cancer patients

Hopper, Mark A. January 2003 (has links)
Since the mid-1970s, there have been an increasingly diverse range of research methods, instruments, and processes of studying social support (Cohen, Underwood, & Gottlieb, 2000) and many definitions of the construct (Hupcey, 1998). Along with the increased interest in the social factors that influence psychological and physical health (Cohen & Syme, 1985), the diverse ways of examining social support have lead to a large literature base ranging from work in the medical and epidemiological fields (Cohen & Syme, 1985; Hupcey, 1998) to social, clinical, and personality psychology (Cohen, Underwood, & Gottlieb, 2000).While there appears to be a great deal of interest in social support, some have argued that there is a basic problem with its definition (Cohen, Underwood, & Gottlieb, 2000; Hupcey, 1998; Shumaker & Brownell, 1984). In the present study, Laireiter and Baumann's (1992) taxonomy of social support was used to review 22 definitions. This taxonomy includes: a) social integration, b) social network, c) supportive climate, d) received support, and e) perceived support. Although most reviewed definitions lack an empirical basis, social support appears to be a valuable concept that deserves further attention (Hupcey, 1998; Laireiter & Baumann, 1992; Vaux, 1988).The present study uses data from a previous study of cancer patients' social support, personality characteristics, and adjustment to their illnesses (Barton, 2001). The five social support measures used in Barton, 2001 were: the Social Network Index, the Family Relationship Index, the Modes of Social Support scale, the Negative Interactions scale, and the Satisfaction with and Received Support scales, appeared to address each of the components of the Laireiter and Baumann's (1992) taxonomy. / Department of Counseling Psychology and Guidance Services

Towards a Chinese conception of social support : a study on the social support networks of Chinese working mothers in Beijing /

Yuen-Tsang, Woon-ki, Angelina. January 1995 (has links)
Thesis (Ph. D.)--University of Hong Kong, 1995. / Includes bibliographical references (leaf 408-428).

Biological and neural mechanisms of social support's effects on health and the experience of pain

Master, Sarah Leah, January 1900 (has links)
Thesis (Ph. D.)--UCLA, 2009. / Vita. Description based on print version record. Includes bibliographical references (leaves 155-177).

Support systems in the life situation of children of divorce

Braude, Diane 04 June 2014 (has links)
M.A. (Social Work) / Please refer to full text to view abstract

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