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In this dissertation, I investigate how online social interactions and user-generated content affect sellers and consumers in online platforms. I conduct three empirical studies to understand the effect of user-generated content in three different types of online platforms: (1) an e-commerce marketplace, (2) an online reviews platform, and (3) an online health community. In study one, I examine how social features (e.g., following others, sharing others’ products) within an electronic commerce marketplace affect status and sales for sellers. This essay contributes to the literature on electronic commerce by deepening the understanding of online social processes among sellers. In study two, I explore how humorous appropriation of an online review platform affects purchase intention and consumer engagement. Utilizing both controlled experiments and analysis of real-world reviews, I demonstrate that humorous appropriation attenuates the effect of review valence on purchase intentions and increases consumer engagement. In study three, I investigate how community ratings are related to patient treatment evaluations and compliance in an online health community. I find that community ratings are positively associated with treatment evaluations and compliance. Moreover, I find that community size and ratings variance moderate the effect of community ratings on treatment evaluations and compliance. Taken together, these essays contribute to the literature on Information Systems by augmenting the understanding of the effects of different types of user-generated content on social (status, engagement, and evaluations) and economic outcomes (purchase intentions and sales). The studies also offer insights for strategic decisions regarding user-generated content in online platforms. / Business Administration/Management Information Systems

No / With the rapid growth of the scale, complexity, and heterogeneity of Peer-to-Peer (P2P) systems, it has become a great challenge to deal with the peer's network-oblivious traffic and self-organization problems. A potential solution is to deploy servers in appropriate locations. However, due to the unique features and requirements of P2P systems, the traditional placement models cannot yield the desirable service performance. To fill this gap, we propose an efficient server placement model for P2P live streaming systems. Compared to the existing solutions, this model takes the Internet Service Provider (ISP) friendly problem into account and can reduce the cross-network traffic among ISPs. Specifically, we introduce the peers' contribution into the proposed model, which makes it more suitable for P2P live streaming systems. Moreover, we deploy servers based on the theoretical solution subject to practical data and apply them to practical live streaming applications. The experimental results show that this new model can reduce the amount of cross-network traffic and improve the system efficiency, has a better adaptability to Internet environment, and is more suitable for P2P systems than the traditional placement models.

The key goal in this work is to enable a flexible ground station that is not constrained to a particular mission or set of hardware. In addition, with the concepts and software produced in this thesis, it will play a significant role in educating engineers and students by providing critical infrastructure and a sandbox for ground station operations. Key pieces of software were developed in this work to create a flexible and robust software-defined ground station. Several digital transmission modes were developed in order to allow communication between the ground station and common amateur radio CubeSats and SmallSats. In order to handle distributed tasks and process at a ground station with multiple servers and controllers, a specialized actor framework was written in Python for ease of use. Actors have the ability to send messages to one another over a network, and they maintain their own memory in order to avoid synchronization problems that come with sharing memory. In addition to the software developed in this work, a novel Peer-to-Peer (P2P) protocol for a network of ground stations is proposed in order to increase coverage and access to spacecraft without requiring centralized server infrastructure. This protocol provides the method to scale the developed software architecture beyond a single ground station. Since the Virginia Tech Ground Station (VTGS) will have many concurrent processes running across multiple servers, it was necessary to apply the actor model in order to simplify the design of the system. The purpose of this thesis is to describe the developed software for the VTGS as well as the P2P protocol for a larger network of ground stations. There are three primary repositories: planck-dsp, gr-vtgs, and pystation. The planck-dsp library and gr-vtgs Out-of-tree (OOT) make up the primary digital signal processing and communications toolboxes, where GNU Radio serves as the scheduler for signal processing blocks used in flow graphs. The pystation module is the extensible software actor framework that connects various systems both locally and remotely. It is also responsible for scheduling and handling ground station requests. While the software was primarily created for the VTGS, it is general enough to apply to other ground station implementations. / Master of Science

No / The surprise advent of the peer-to-peer payment system Bitcoin in 2009 has raised various concerns regarding its relationship to established economic market ideologies. Unlike fiat currencies, Bitcoin is based on open-source software; it is a secure cryptocurrency, traded as an investment between two individuals over the internet, with no bank involvement. Computationally, this is a very innovative solution, but Bitcoin’s popularity has raised a number of security and trust concerns among mainstream economists. With cities and countries, including San Francisco and Germany, using Bitcoin as a unit of account in their financial systems, there is still a lack of understanding and a paucity of models for studying its use, and the role Bitcoin might play in real physical economies. This project tackles these issues by analysing the ramifications of Bitcoin within economic models, by building a computational model of the currency to test its performance in financial market models. The project uses established agent-based modelling techniques to build a decentralised Bitcoin model, which can be ‘plugged into’ existing agent-based models of key economic and financial markets. This allows various metrics to be subjected to critical analysis, gauging the progress of digital economies equipped with Bitcoin usage. This project contributes to the themes of privacy, consent, security and trust in the digital economy and digital technologies, enabling new business models of direct relevance to NEMODE. As computer scientists, we consider Bitcoin from a technical perspective; this contrasts with and complements other current Bitcoin research, and helps document the realizable risks Bitcoin and similar currencies bring to our current economic world. This report outlines a comprehensive collection of risks raised by Bitcoin. Risk management is a discipline that can be used to address the possibility of future threats which may cause harm to the existing systems. Although there has been considerable work on analysing Bitcoin in terms of the potential issues it brings to the economic landscape, this report performs a first ever attempt of identifying the threats and risks posed by the use of Bitcoin from the perspective of computational modeling and engineering. In this project we consider risk at all levels of interaction when Bitcoin is introduced and transferred across the systems. We look at the infrastructure and the computational working of the digital currency to identify the potential risks it brings. Additional information can be seen in our forthcoming companion report on the detailed modeling of Bitcoin.

This thesis describes the application of microprocessor based relays with internet communication capabilities in distribution protection systems. The traditional distribution protection system (recloser, sectionalizers) was configured to automatically isolate faulted circuits as well as to reenergize unfaulted loads after a certain number of reclosing operations. Internet Peer-to-Peer communication enables distribution relays to communicate with others connected to the communication network without having a master device. According to the results, the addition of peer-to-peer communication to a traditional distribution protection system significantly enhances its general performance eliminating undesired losses of unfaulted load. Additionally, it reduces outage duration as well as thermal and mechanical stress due to successive re-energizations under faults condition. / Master of Science

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Legal issues of the Internet from the scope of international and national law Global internet network has changed the social, political and business life of most people in the World. Communication is much faster, the flow of information all around the World takes a few seconds. Exchange of political opinions, personal and business information, works protected by copyright and other information has become unstoppable. Members of the international community are trying to tackle this new challenge to their legal and political systems. This diploma thesis is describing some arreas of private law where Internet plays the most important role and has changed the scope and interpretation of many legal rules. The work is dividend into two main parts. The first one deals with general aspects of the Internet such as its history, architecture, different regulatory layers, the copyright law on-line, general legal issues arising from the Yahoo! case and its impact on political systems. The second part describes more specific areas mainly focused on the protection of personality and personal data in the on-line environment. To be more specific, there are chapters dealing with communication software, social networks, direct business and usage of the Internet for business reasons. Specific chapter is dedicated to...

Com o advento da internet, surgem no campo da filantropia plataformas digitais que utilizam o poder de mobilização de indivíduos da web 2.0 para apoiar financeiramente projetos socioambientais. Esta dissertação tem por base as experiências da startup Eventos do Bem, que utiliza o método de angariação online Peer-to- Peer (P2P). A abordagem digital do método de captação de recursos P2P consiste na elaboração de campanhas promovidas por indivíduos online os quais podem utilizar seus eventos pessoais prol de uma causa social - como aniversários, casamentos entre outros - para mobilizar sua rede de contatos propondo que seus conhecidos doem para sua campanha ao invés de os presentearem no aniversário. As experiências na realização de campanhas digitais em prol de organizações sociais no referido empreendimento, elucubraram problemas relativos à performance financeira das campanhas. Logo, esta pesquisa foi realizada com o objetivo de propor diretrizes e práticas que potencializem o sucesso deste tipo de arrecadação online. Visto ser um modelo aplicado de forma pioneira no país, como metodologia, optou-se pela estratégia de estudos de caso múltiplos com base em YIN (1994) na qual, em conjunto com o estudo da startup Eventos do Bem, selecionou-se a plataforma estadunidense Charity:Water, referência em angariação P2P. Como unidades de análise, foram abordadas as campanhas de angariação realizadas em ambas as plataformas, focando na categoria de campanhas de aniversário. Logo, o trajeto desta pesquisa delineou-se nas fases: (a) análise da experiência da startup Eventos do Bem, em paralelo com a leitura do referencial teórico pertinente; (b) pesquisa e seleção da plataforma Charity:Water; (c) estudo e realização de 46 entrevistas, compondo-se em 6 entrevistas com funcionários do Charity:Water e 40 efetivadas com criadores de campanhas de aniversário em ambas as plataformas; (d) análise de fatores e práticas influenciadoras das campanhas promovidas nos casos abordados; (e) estudo cross- case e análise dos resultados obtidos. Como resultado da pesquisa, foi delineado um procedimento de boas práticas para potencializar a performance das campanhas digitais, destacando-se ações referentes à interação individual do criador da campanha com toda a sua rede de contatos, a persistência no pedido e a realização de um discurso do pedido de doação com qualidade, isto é, que apresente argumentos para persuadir doadores mais emocionais como também os mais racionais e lógicos. Desta forma, o estudo contribuiu para expandir o debate de captação de recursos online e aponta inovações da técnica P2P no que tange à mecânica do processo de decisão para doar e demonstra que a técnica pode fornecer resultados que vão além da angariação de recursos, estimulando maior engajamento social dos participantes. / With the advent of the Internet, philanthropy is emerging in digital platforms that use the mobilization power of web 2.0 individuals to financially support social and environmental projects. This dissertation is based on the experiences of the startup Eventos do Bem, which uses the Peer-to-Peer (P2P) online raising method. The digital approach of the P2P method of fundraising consists of the elaboration of campaigns promoted by individuals online who can use their personal events for a social cause - such as anniversaries, weddings and others - to mobilize their network of contacts by proposing that their acquaintances ache for their campaign instead of giving them on their birthday. The experiences in the accomplishment of digital campaigns in favor of social organizations in the mentioned enterprise, they have presented problems related to the financial performance of the campaigns. Therefore, this research was carried out with the objective of proposing guidelines and practices that will enhance the success of this type of online collection. As a model pioneered in the country, as a methodology, we chose the strategy of multiple case studies based on YIN (1994) in which, together with the study of the startup Eventos do Bem, we selected the platform American Charity: Water, reference in P2P fundraising. As units of analysis, the campaigns of raising were carried out in both platforms, focusing on the category of birthday campaigns.Therefore, the study\'s path was delineated in the phases: (a) analysis of the startup experience of the Good Events, in parallel with the reading of the relevant theoretical reference; (B) research and selection of the Charity: Water platform; (C) study and performance of 46 interviews, comprising 6 interviews with Charity: Water employees and 40 interviews with fundraisers on both platforms; (D) analysis of factors and practices influencing the campaigns promoted in the cases addressed; (E) cross-case study and analysis of the results obtained. As a result, a procedure of good practices was designed to potentiate fundraising P2P performance, highlighting actions regarding the individual interaction of the campaigner with his entire network of contacts, a persistence without request and realization of a speech of the Request Of giving with quality, is, and presents arguments to persuade donors more emotional as also the most rational and logical. In this way, the study contributed to expand the online fundraising debate and points out innovations of the P2P technique regarding the mechanics of the decision process to donate and demonstrates that the technique can provide results that go beyond fundraising, Stimulating greater social engagement of participants.