Asymptotic theory of time varying networks with memory and heterogeneous activation pattern

In this thesis work we develop a new generative model of social networks belonging to the family of Time Varying Networks. The importance of correctly modelling the mechanisms shaping the growth of a network and the dynamics of the edges activation and inactivation are of central importance in network science. Indeed, by means of generative models that mimic the real-world dynamics of contacts in social networks it is possible to forecast the outcome of an epidemic process, optimize the immunization campaign or optimally spread an information among individuals. This task can now be tackled taking advantage of the recent availability of large-scale, high-quality and time-resolved datasets. This wealth of digital data has allowed to deepen our understanding of the structure and properties of many real-world networks. Moreover, the empirical evidence of a temporal dimension in networks prompted the switch of paradigm from a static representation of graphs to a time varying one. In this work we exploit the Activity-Driven paradigm (a modeling tool belonging to the family of Time-Varying-Networks) to develop a general dynamical model that encodes fundamental mechanism shaping the social networks' topology and its temporal structure: social capital allocation and burstiness. The former accounts for the fact that individuals does not randomly invest their time and social interactions but they rather allocate it toward already known nodes of the network. The latter accounts for the heavy-tailed distributions of the inter-event time in social networks. We then empirically measure the properties of these two mechanisms from seven real-world datasets and develop a data-driven model, analytically solving it. We then check the results against numerical simulations and test our predictions with real-world datasets, finding a good agreement between the two. Moreover, we find and characterize a non-trivial interplay between burstiness and social capital allocation in the parameters phase space. Finally, we present a novel approach to the development of a complete generative model of Time-Varying-Networks. This model is inspired by the Kaufman's adjacent possible theory and is based on a generalized version of the Polya's urn. Remarkably, most of the complex and heterogeneous feature of real-world social networks are naturally reproduced by this dynamical model, together with many high-order topological properties (clustering coefficient, community structure etc.).

Religião, redes sociais e capital social no Município de Rio Grande da Serra na Região do Grande ABC Paulista. Estudo das trocas materiais e simbólicas em contexto de periferia urbana

O município de Rio Grande da Serra está situado em uma região Grande ABC paulista reconhecida nacionalmente por seu desenvolvimento econômico e industrial e pelas lutas políticas e sindicais. Paradoxalmente, se configura, social e territorialmente falando, por uma região de periferia urbana. Resultado da forma como a urbanização, na sociedade moderna, conforma o espaço em regiões centrais e periféricas. Localizado no caminho que ligava Santos à Mogi das Cruzes (século XIX) povoado de Geribatiba decorrente das transformações urbanas ocorridas em toda a região, conquistaria, nos anos 1960, sua autonomia político-administrativa. Nas décadas seguintes testemunhou intenso crescimento populacional, resultado do processo migratório, principalmente de mineiros e nordestinos que tinham as cidades, e indústrias, de São Paulo e Grande ABC como destino. Esse deslocamento de pessoas, e as redes formadas em seu em torno, contribuiu para o desenvolvimento de seu campo religioso. Atualmente, com uma população, em torno, de 46 mil habitantes, possui aproximadamente 180 locais de cerimônias religiosas. Nesse contexto, a tese analisa a inserção regional socioeconômica e religiosa de Rio Grande da Serra, a partir de dados comparativos com os demais municípios, e discute como o regionalismo tem contribuído para seu desenvolvimento econômico. Realiza a caracterização das periferias urbanas, discutindo aspectos que lhes são inerentes, como segregação e vulnerabilidade social. Nesse sentido, a investigação possibilitou a identificação do perfil socioeconômico (renda e escolaridade) dos participantes dos grupos religiosos (católicos, evangélicos, kardecistas e umbandistas), permitindo, também, identificar desigualdades sociais no interior de seu território, constatando que determinados bairros são mais vulneráveis do que outros. Considerando que esse estudo examina a capacidade das redes sociais e religiosas, de aumentar o capital social de seus participantes, foi realizado o mapeamento e etnografia das diversas práticas associativas, mais ou menos formais e estruturadas, de forma a analisar os elementos materiais e simbólicos por elas produzidos. Constatou-se, apoiado na aplicação de questionários, entrevistas e observação participativa, que, a partir do habitus religioso de cada grupo, as redes possibilitam no âmbito econômico questões como emprego e renda ou auxílio em necessidades básicas de sobrevivência, através de campanhas e trabalhos sociais. No âmbito simbólico, as redes propiciam questões importantes à existência humana, como a crença na salvação ou evolução da alma, socialização, autoestima, prestígio ou ainda a expectativa de cura ou tratamento de dependência química. Pôde-se aferir que, a despeito das diferentes formas como cada grupo, e seus participantes, se apropriam do capital social, as redes sociais e religiosas, no município, funcionam como redes de proteção, especialmente à população em situação alta de vulnerabilidade social.

A Congregação Cristã no Brasil numa área de alta vulnerabilidade social no ABC paulista: aspectos de sua tradição e transmissão religiosa - a instituição e os sujeitos

Esta tese estuda a tradição e transmissão religiosa da Congregação Cristã no Brasil, numa área de maior vulnerabilidade social, a partir da instituição e dos sujeitos. A reprodução religiosa, na modernidade contemporânea, é dificultada pela capacidade diminuída das instituições religiosas de regular as crenças dos seus fiéis, e esta capacidade é analisada no caso da Congregação Cristã no Brasil, num bairro de alta vulnerabilidade social, na fronteira entre São Bernardo do Campo e Diadema. São estudadas as dimensões sociais da Congregação Cristã no Brasil, a partir de um olhar estatístico do campo pentecostal brasileiro. É analisada a realidade social local e elaborada a situação periférica específica do bairro estudado. Uma etnografia do culto da Congregação Cristã fornece os dados para análise dos atores no culto, do processo ritual, e da função do culto para a articulação da identidade religiosa. Finalmente é elaborada, a partir de entrevistas em profundidade e detida observação de campo, uma etnografia dos sujeitos membros da Congregação Cristã, homens e mulheres, em situações diferenciadas de vulnerabilidade. Analisa-se quais redes sociais, internas na Congregação Cristã no Brasil e externas, estes membros criam e até onde as doutrinas e práticas da Congregação, transmitidas no rito, dispositivo de reprodução institucional por excelência, conseguem formar a subjetividade dos seus fiéis, entendida como complexo conjunto de percepção, afeto, pensamento, desejo e medo.(AU)

RELIGIÃO E CAPITAL SOCIAL NA PERIFERIA URBANA DO GRANDE ABC PAULISTA UMA ANÁLISE DAS REDES SOCIAIS PENTECOSTAIS NO MUNICÍPIO DE RIO GRANDE DA SERRA

A presente pesquisa analisa igrejas evangélicas pentecostais no município de Rio Grande da Serra, região do Grande ABC Paulista. Busca identificar qual é o papel social desses grupos religiosos de grande crescimento no município junto aos seus membros em situação socioeconômica frágil, tanto quanto para a população carente da cidade. A partir de uma reflexão acerca da constituição de espaços territoriais periféricos , e das práticas associativas nesses espaços, nosso objetivo é estudar o associativismo religioso formal e informal, e a construção de redes sociais em seu entorno, e a sua contribuição para o aumento do capital social, entendido este, segundo Bourdieu, como agregado de benefícios materiais e simbólicos, de seus participantes. A pesquisa leva em consideração que a cidade caracteriza-se por ser uma região de periferia, em que parcela importante da população vive em situação de segregação, riscos e vulnerabilidade social.

Perspectivas e metodologias de pesquisa da Comunicação Social no contexto da internet com o Big Data e da especialização Data Scientist

O trabalho desenvolvido analisa a Comunicação Social no contexto da internet e delineia novas metodologias de estudo para a área na filtragem de significados no âmbito científico dos fluxos de informação das redes sociais, mídias de notícias ou qualquer outro dispositivo que permita armazenamento e acesso a informação estruturada e não estruturada. No intento de uma reflexão sobre os caminhos, que estes fluxos de informação se desenvolvem e principalmente no volume produzido, o projeto dimensiona os campos de significados que tal relação se configura nas teorias e práticas de pesquisa. O objetivo geral deste trabalho é contextualizar a área da Comunicação Social dentro de uma realidade mutável e dinâmica que é o ambiente da internet e fazer paralelos perante as aplicações já sucedidas por outras áreas. Com o método de estudo de caso foram analisados três casos sob duas chaves conceituais a Web Sphere Analysis e a Web Science refletindo os sistemas de informação contrapostos no quesito discursivo e estrutural. Assim se busca observar qual ganho a Comunicação Social tem no modo de visualizar seus objetos de estudo no ambiente das internet por essas perspectivas. O resultado da pesquisa mostra que é um desafio para o pesquisador da Comunicação Social buscar novas aprendizagens, mas a retroalimentação de informação no ambiente colaborativo que a internet apresenta é um caminho fértil para pesquisa, pois a modelagem de dados ganha corpus analítico quando o conjunto de ferramentas promovido e impulsionado pela tecnologia permite isolar conteúdos e possibilita aprofundamento dos significados e suas relações.

REDE SOCIAL CAFÉS DO BRASIL: UMA ANÁLISE COMUNICACIONAL

Este trabalho teve como objetivo descrever e analisar a rede social Cafés do Brasil rede social na Internet criada para integrar cafeicultores, agrônomos, pesquisadores e demais agentes que atuam no agronegócio café - a partir da comunicação estabelecida entre seus atores, procurando, ainda, avaliar a adequação desta nova formatação de rede social para o processo de comunicação à transferência de informação tecnológica ao setor produtivo e para a interação dos agentes que atuam nos diversos segmentos da cadeia agroindustrial do café. A principal metodologia empregada foi a Análise de Redes Sociais (ARS) que, por meio de análises matemáticas e estatísticas, fundamentadas na modelagem por meio de grafos (sociogramas), permitiu-nos não só descrever as propriedades estruturais da rede estudada, como interpretar e criar significados para as relações sociais identificadas na rede. Os resultados obtidos caracterizam a rede Cafés do Brasil como uma rede pouco conectada tanto no âmbito das relações estabelecidas entre seus atores pela troca de mensagens por e-mail, quanto nos espaços destinados à discussão e debates sobre temas relacionados ao setor. À guisa de conclusões pode-se afirmar que, apesar de possuir estrutura aberta e flexível, e ferramentas que facilitam o compartilhamento de informações, a rede Cafés do Brasil não foi capaz até o momento de integrar de forma satisfatória os agentes da cadeia agroindustrial do café que dela participam, e sua formatação atual não favorece substancialmente o processo de comunicação para a transferência de tecnologia ao setor produtivo. Com base no estudo, apresentamos sugestões para ajustes na configuração da rede de forma a adequá-la aos objetivos para os quais foi construída.(AU)

Essays on the Economics of Networks Under Incomplete Information

Social networks constitute a major channel for the diffusion of information and the formation of attitudes in a society. Introducing a dynamic model of social learning, the first part of this thesis studies the emergence of socially influential individuals and groups, and identifies the characteristics that make them influential. The second part uses a Bayesian network game to analyse the role of social interaction and conformism in the making of decisions whose returns or costs are ex ante uncertain.

Word of mouth communication within online communities:conceptualizing the online social network

Word of mouth (WOM) communication is a major part of online consumer interactions, particularly within the environment of online communities. Nevertheless, existing (offline) theory may be inappropriate to describe online WOM and its influence on evaluation and purchase.The authors report the results of a two-stage study aimed at investigating online WOM: a set of in-depth qualitative interviews followed by a social network analysis of a single online community. Combined, the results provide strong evidence that individuals behave as if Web sites themselves are primary "actors" in online social networks and that online communities can act as a social proxy for individual identification. The authors offer a conceptualization of online social networks which takes the Web site into account as an actor, an initial exploration of the concept of a consumer-Web site relationship, and a conceptual model of the online interaction and information evaluation process. © 2007 Wiley Periodicals, Inc. and Direct Marketing Educational Foundation, Inc.

Efficiency improvements to the Groupe Special Mobile (GSM) digital mobile radio system

Groupe Spécial Mobile (GSM) has been developed as the pan-European second generation of digital mobile systems. GSM operates in the 900 MHz frequency band and employs digital technology instead of the analogue technology of its predecessors. Digital technology enables the GSM system to operate in much smaller zones in comparison with the analogue systems. The GSM system will offer greater roaming facilities to its subscribers, extended throughout the countries that have installed the system. The GSM system could be seen as a further enhancement to European integration. GSM has adopted a contention-based protocol for multipoint-to-point transmission. In particular, the slotted-ALOHA medium access protocol is used to coordinate the transmission of the channel request messages between the scattered mobile stations. Collision still happens when more than one mobile station having the same random reference number attempts to transmit on the same time-slot. In this research, a modified version of this protocol has been developed in order to reduce the number of collisions and hence increase the random access channel throughput compared to the existing protocol. The performance evaluation of the protocol has been carried out using simulation methods. Due to the growing demand for mobile radio telephony as well as for data services, optimal usage of the scarce availability radio spectrum is becoming increasingly important. In this research, a protocol has been developed whereby the number of transmitted information packets over the GSM system is increased without any additional increase of the allocated radio spectrum. Simulation results are presented to show the improvements achieved by the proposed protocol. Cellular mobile radio networks commonly respond to an increase in the service demand by using smaller coverage areas. As a result, the volume of the signalling exchanges increases. In this research, a proposal for interconnecting the various entitles of the mobile radio network over the future broadband networks based on the IEEE 802.6 Metropolitan Area Network (MAN) is outlined. Simulation results are presented to show the benefits achieved by interconnecting these entities over the broadband Networks.

Social network theory and the sales manager role:engineering the right relationship flows

Sales leadership research has typically taken a leader-focused approach, investigating key questions from a top-down perspective. Yet considerable research outside sales has advocated a view of leadership that takes into account the fact that employees look beyond a single designated individual for leadership. In particular, the social networks of leaders have been a popular topic of investigation in the management literature, although coverage in the sales literature remains rare. The present paper conceptualizes the sales leadership role as one in which the leader must manage a network of simultaneous relationships; several types of sales manager relationships, such as the sales-manager-to-top-manager and the sales-manager-to-sales manager relationships, have received limited attention in the sales literature to date. Taking an approach based on social network theory, we develop a conceptualization of the sales manager as a "network engineer," who must manage multiple relationships, and the flows between them. Drawing from this model, we propose a detailed agenda for future sales research. © 2012 PSE National Educational Foundation. All rights reserved.

Incorporating social role theory into topic models for social media content analysis

In this paper, we explore the idea of social role theory (SRT) and propose a novel regularized topic model which incorporates SRT into the generative process of social media content. We assume that a user can play multiple social roles, and each social role serves to fulfil different duties and is associated with a role-driven distribution over latent topics. In particular, we focus on social roles corresponding to the most common social activities on social networks. Our model is instantiated on microblogs, i.e., Twitter and community question-answering (cQA), i.e., Yahoo! Answers, where social roles on Twitter include "originators" and "propagators", and roles on cQA are "askers" and "answerers". Both explicit and implicit interactions between users are taken into account and modeled as regularization factors. To evaluate the performance of our proposed method, we have conducted extensive experiments on two Twitter datasets and two cQA datasets. Furthermore, we also consider multi-role modeling for scientific papers where an author's research expertise area is considered as a social role. A novel application of detecting users' research interests through topical keyword labeling based on the results of our multi-role model has been presented. The evaluation results have shown the feasibility and effectiveness of our model.

Personalized Question-Answering Mobile System

Mobile messaging is an integral and vital part of the mobile industry and contributes significantly to worldwide total mobile service revenues. In today’s competitive world, differentiation is a significant factor in the success of the business communication. SMS (Short Message Service) provides a powerful vehicle for service differentiation. What is missing, however, is the availability of personalized SMS messages. In particular, the exploitation of user profile information allows a selection and content delivery that meets preferences and interests for the individual. Personalization of mobile messages is important in today’s service-oriented society, and has proven to be crucial for the acceptance of services provided by the mobile telecommunication networks. In this paper we focus on user profile description and the mechanism for delivering the relevant information to the mobile user in accordance with his/her profile.

Quality-driven resource utilization methods for video streaming in wireless communication networks

This research is focused on the optimisation of resource utilisation in wireless mobile networks with the consideration of the users’ experienced quality of video streaming services. The study specifically considers the new generation of mobile communication networks, i.e. 4G-LTE, as the main research context. The background study provides an overview of the main properties of the relevant technologies investigated. These include video streaming protocols and networks, video service quality assessment methods, the infrastructure and related functionalities of LTE, and resource allocation algorithms in mobile communication systems. A mathematical model based on an objective and no-reference quality assessment metric for video streaming, namely Pause Intensity, is developed in this work for the evaluation of the continuity of streaming services. The analytical model is verified by extensive simulation and subjective testing on the joint impairment effects of the pause duration and pause frequency. Various types of the video contents and different levels of the impairments have been used in the process of validation tests. It has been shown that Pause Intensity is closely correlated with the subjective quality measurement in terms of the Mean Opinion Score and this correlation property is content independent. Based on the Pause Intensity metric, an optimised resource allocation approach is proposed for the given user requirements, communication system specifications and network performances. This approach concerns both system efficiency and fairness when establishing appropriate resource allocation algorithms, together with the consideration of the correlation between the required and allocated data rates per user. Pause Intensity plays a key role here, representing the required level of Quality of Experience (QoE) to ensure the best balance between system efficiency and fairness. The 3GPP Long Term Evolution (LTE) system is used as the main application environment where the proposed research framework is examined and the results are compared with existing scheduling methods on the achievable fairness, efficiency and correlation. Adaptive video streaming technologies are also investigated and combined with our initiatives on determining the distribution of QoE performance across the network. The resulting scheduling process is controlled through the prioritization of users by considering their perceived quality for the services received. Meanwhile, a trade-off between fairness and efficiency is maintained through an online adjustment of the scheduler’s parameters. Furthermore, Pause Intensity is applied to act as a regulator to realise the rate adaptation function during the end user’s playback of the adaptive streaming service. The adaptive rates under various channel conditions and the shape of the QoE distribution amongst the users for different scheduling policies have been demonstrated in the context of LTE. Finally, the work for interworking between mobile communication system at the macro-cell level and the different deployments of WiFi technologies throughout the macro-cell is presented. A QoEdriven approach is proposed to analyse the offloading mechanism of the user’s data (e.g. video traffic) while the new rate distribution algorithm reshapes the network capacity across the macrocell. The scheduling policy derived is used to regulate the performance of the resource allocation across the fair-efficient spectrum. The associated offloading mechanism can properly control the number of the users within the coverages of the macro-cell base station and each of the WiFi access points involved. The performance of the non-seamless and user-controlled mobile traffic offloading (through the mobile WiFi devices) has been evaluated and compared with that of the standard operator-controlled WiFi hotspots.

A computational approach to measuring the correlation between expertise and social media influence for celebrities on microblogs

Existing approaches of social influence analysis usually focus on how to develop effective algorithms to quantize users' influence scores. They rarely consider a person's expertise levels which are arguably important to influence measures. In this paper, we propose a computational approach to measuring the correlation between expertise and social media influence, and we take a new perspective to understand social media influence by incorporating expertise into influence analysis. We carefully constructed a large dataset of 13,684 Chinese celebrities from Sina Weibo (literally 'Sina microblogging'). We found that there is a strong correlation between expertise levels and social media influence scores. In addition, different expertise levels showed influence variation patterns: high-expertise celebrities have stronger influence on the 'audience' in their expertise domains.

Progmosis:evaluating risky individual behavior during epidemics using mobile network data

The possibility to analyze, quantify and forecast epidemic outbreaks is fundamental when devising effective disease containment strategies. Policy makers are faced with the intricate task of drafting realistically implementable policies that strike a balance between risk management and cost. Two major techniques policy makers have at their disposal are: epidemic modeling and contact tracing. Models are used to forecast the evolution of the epidemic both globally and regionally, while contact tracing is used to reconstruct the chain of people who have been potentially infected, so that they can be tested, isolated and treated immediately. However, both techniques might provide limited information, especially during an already advanced crisis when the need for action is urgent. In this paper we propose an alternative approach that goes beyond epidemic modeling and contact tracing, and leverages behavioral data generated by mobile carrier networks to evaluate contagion risk on a per-user basis. The individual risk represents the loss incurred by not isolating or treating a specific person, both in terms of how likely it is for this person to spread the disease as well as how many secondary infections it will cause. To this aim, we develop a model, named Progmosis, which quantifies this risk based on movement and regional aggregated statistics about infection rates. We develop and release an open-source tool that calculates this risk based on cellular network events. We simulate a realistic epidemic scenarios, based on an Ebola virus outbreak; we find that gradually restricting the mobility of a subset of individuals reduces the number of infected people after 30 days by 24%.