Página 15 dos resultados de 2591 itens digitais encontrados em 0.035 segundos

A framework for wireless sensor networks management for precision viticulture and agriculture based on IEEE 1451 standard

Fernandes, Miguel A.; Matos, Samuel G.; Peres, Emanuel; Cunha, Carlos R.; López, Juan A.; Ferreira, P.J.S.G.; Reis, M.J.C.S.; Morais, Raul
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
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Precision viticulture (PV) and precision agriculture (PA) requires the acquisition and proce ssing of a vast collection of data coming typically from large scale and heterogeneous sensor networks. Unfortunately, sensor integration is far from being simple due to the number of incompatible network specifications and platforms. The adoption of a common, standard communication interfa ce would allow the engineer to abstract the relation between the sensor and the network. This would reduce the development efforts and emerge as an important step towards the adoption of ‘‘plug-and-play’’ technology in PA/PV sensor networks. This paper explores this need and introduces a framework for smart data acquisition in PA/PV that relies on the IEEE 1451 family of standards, which addresses the transducer-to -network interoperability issues. The framework includes a ZigBee end device (sMPWiNodeZ), as an IEEE 1451 WTIM (Wireless Transducer Interface Module), and an IEEE 1451 NCAP (Network Capable Application Processor) that acts as gateway to an information service provider and WSN (Wireless Sensor Network) coordinator. The paper discusses the proposed IEEE 1451 system architecture and its benefits in PA/PV and closes with results/lessons learned from in-field trials towards smarter WSN.

Multiple Pathways Analysis of Brain Functional Networks from EEG Signals: An Application to Real Data

FALLANI, Fabrizio De Vico; RODRIGUES, Francisco Aparecido; COSTA, Luciano da Fontoura; ASTOLFI, Laura; CINCOTTI, Febo; MATTIA, Donatella; SALINARI, Serenella; BABILONI, Fabio
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
Português
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In the present study, we propose a theoretical graph procedure to investigate multiple pathways in brain functional networks. By taking into account all the possible paths consisting of h links between the nodes pairs of the network, we measured the global network redundancy R (h) as the number of parallel paths and the global network permeability P (h) as the probability to get connected. We used this procedure to investigate the structural and dynamical changes in the cortical networks estimated from a dataset of high-resolution EEG signals in a group of spinal cord injured (SCI) patients during the attempt of foot movement. In the light of a statistical contrast with a healthy population, the permeability index P (h) of the SCI networks increased significantly (P < 0.01) in the Theta frequency band (3-6 Hz) for distances h ranging from 2 to 4. On the contrary, no significant differences were found between the two populations for the redundancy index R (h) . The most significant changes in the brain functional network of SCI patients occurred mainly in the lower spectral contents. These changes were related to an improved propagation of communication between the closest cortical areas rather than to a different level of redundancy. This evidence strengthens the hypothesis of the need for a higher functional interaction among the closest ROIs as a mechanism to compensate the lack of feedback from the peripheral nerves to the sensomotor areas.; COST EU[BM 0601]; COST EU; European ICT Programme Project[FP7-224631]; European ICT Programme Project; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq[301303/06-1]; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP[05/00587-5]

Proposta de um processo sistemático baseado em métricas não-dicotômicas para avaliação de predição de links em redes de coautoria.; Proposal of a systematic process based on non-dichotomic metrics for evaluation of link prediction in co-authorship networks.

Silva, Elisandra Aparecida Alves da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/03/2011 Português
Relevância na Pesquisa
35.72%
Predição de Links é uma área de pesquisa importante no contexto de Análise de Redes Sociais tendo em vista que predizer sua evolução é um mecanismo útil para melhorar e propiciar a comunicação entre usuários. Nas redes de coautoria isso pode ser utilizado para recomendação de usuários com interesses de pesquisa comuns. Este trabalho propõe um processo sistemático baseado em métricas não-dicotômicas para avaliação de predição de links em redes de coautoria, sendo considerada a definição de métodos para as seguintes tarefas identificadas: seleção de dados, determinação de novos links e avaliação dos resultados. Para seleção de dados definiu-se um sensor fuzzy baseado em atributos dos nós. O uso de composições fuzzy foi considerado para determinação de novos links _ponderados_ entre dois autores, adotando-se não apenas atributos dos nós, mas também a combinação de atributos de outros links observados. O link ponderado é denominado _qualidade da relação_ e é obtido pelo uso de propriedades estruturais da rede. Para avaliação dos resultados foi proposta a curva ROC fuzzy, que permite explorar os pesos dos links não apenas para ordenação dos exemplos.; Link prediction is an important research line in the Social Network Analysis context...

Grafos evolutivos na modelagem e análise de redes dinâmicas; Evolving Graphs in the Modeling and Analysis of Dynamic Networks

Floriano, Paulo Henrique
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/02/2012 Português
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Atualmente, muitas redes com características dinâmicas estão em funcionamento (por exemplo MANETs, DTNs, redes oportunistas, etc). Neste trabalho, estudamos um modelo para estas redes chamado de Grafos Evolutivos, que permite expressar a dinamicidade das conexões entre nós por meio de uma simples extensão da estrutura comum de grafos. Esta modelagem é utilizada no arcabouço proposto por Casteigts et al. para definir algoritmos distribuídos em redes dinâmicas, que utiliza grafos evolutivos para representar a topologia da rede e renomeação de rótulos para expressar a comunicação entre os nós. Utilizamos esta abordagem para estudar o problema da exclusão mútua distribuída em redes dinâmicas e diversos algoritmos propostos para ele, a fim de definir e validar suas condições necessárias e suficientes de conectividade em redes dinâmicas. Além da formalização de algoritmos, o modelo de grafos evolutivos também pode ser utilizado para analisar redes dinâmicas. Rastros de redes dinâmicas reais são amplamente utilizados na literatura para estudos de algoritmos pois estes geram resultados mais realísticos do que redes simuladas com padrões de movimento. A partir dos detalhes de cada conexão entre nós de um destes rastros...

Proposta e modelagem de comunicação segura para redes veiculares (VANETS)

Barbieri, Wellington Reina
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 90 f. : il.
Português
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Pós-graduação em Ciência da Computação - IBILCE; Os avanços constantes da tecnologia, a facilidade da troca de informação em todas as áreas conhecidas e equipamentos cada vez mais sofisticados apresentam um cenário onde se torna imprescindível uma infraestrutura que proporcione comunicação entre os veículos que circulam nas cidades e rodovias, para haver uma maior segurança no tráfego. Esta ferramenta conhecida como VANET (Vehicular Ad Hoc NETwork) é uma subclasse da redes Ad Hoc que tem como objetivo a comunicação entre veículos e/ou entre veículos e uma infraestrutura de acostamento, e tem a finalidade de proporcionar segurança e autonomia nas vias rodoviárias. Mas esta troca de informação ainda é frágil e cada vez mais fácil de ser interceptada. Com o intuito de minimizar as invasões e interceptações, foi proposta a utilização do protocolo TESLA (Timed Efficient Stream Loss-Tolerant Authentication) que é um protocolo de segurança utilizado na troca de informações nas comunicações e baseiase na perda de tempo de sincronização entre o emissor e o receptor. O objetivo deste trabalho é modelar em UML e Fluxograma a alteração na comunicação na rede VANET, sendo possível escolher qual protocolo será utilizado e a segurança no protocolo TESLA...

Algoritmos de escalonamento e de handoff para redes 3G e 4G; Scheduling and handoff algorithms for 3g and 4G networks

Leandro Bento Sena Marques
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/10/2010 Português
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Este trabalho apresenta um estudo de desempenho dos enlaces diretos dos sistemas CDMA 1xEVDO RA, UMTS/HSDPA e WiMAX com ênfase em escalonadores de dados e nos novos critérios de aceitação de tráfego handoff horizontal e vertical para redes 3G e 4G. Estes novos critérios de aceitação de tráfego handoff horizontal e vertical levam em conta a ocupação do enlace, a ocupação do buffer, a potência do sinal recebido (RSS) e o tamanho do quantum (DRR) como parâmetros para a decisão do processo de handoff. Além disso, o estudo considera os escalonadores de dados Max C/I (Maximum Carrier Interference), DRR (Deficit Round Robin), PF (Proportional Fair), Pr (Prioritário) e a nova proposta Pr/PF (Priority Proportional Fair). Os critérios combinados aos escalonadores são avaliados pormeio de métricas de QoS em função da chegada de tráfego HTTP interno ou em handoff. Os resultados mostraram que conforme o critério e o escalonador adotados, podem assegurar a QoS dos sistemas móveis e ainda aceitar uma boa quantidade de tráfego handoff. O estudo é baseado em simulações computacionais através da ferramenta de software Matlab; This work presents a performance study of the forward links of CDMA 1xEV-DO RA, UMTS/HSDPA and WiMAX systems with emphasis on data schedulers and new criteria for horizontal and vertical handoff traffic acceptance in the 3G and 4G networks. These new criteria for horizontal and vertical handoff traffic acceptance take into account the link occupation...

The use of communication technologies to support teaching and learning practices in portuguese higher education

Ramos, Fernando; Pinto, Marta; Coelho, Dalila; Raposo, Rui; Almeida, Pedro; Pedro, Luís; Batista, João
Fonte: IATED Publicador: IATED
Tipo: Conferência ou Objeto de Conferência
Português
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35.73%
The use of Communication Technologies (CTs) to support teaching and learning in higher education (HE) has emerged as a research topic worldwide. At the University of Aveiro (Portugal) the TRACER project began researching in 2011 the use of CTs to support teaching and learning practices in Portuguese Public Higher Education Institutions (PPHEIs). Data was collected through two online surveys distributed at two different moments during the project’s life cycle. The first survey, answered by decision makers at the rectory level of the PPHEIs, focused on the institutional perspective of the support to the use of CT in their teaching and learning related activities. The second survey, answered by teachers from the same PPHEIs, focused on the perspective of the use of CT in their teaching practice. Results from the institutional perspective globally show that from the total of courses of all existing cycles in respondent Higher Education Institutions (HEIs), 5.9% are delivered entirely online and 4.2% in a blended modality, most of them at undergraduate and post-graduate (master) levels. Regarding the provision of online learning management systems to support teaching and learning, results showed that the open source platform Moodle is the most commonly adopted...

Integration of extracellular RNA profiling data using metadata, biomedical ontologies and Linked Data technologies

Subramanian, Sai Lakshmi; Kitchen, Robert R.; Alexander, Roger; Carter, Bob S.; Cheung, Kei-Hoi; Laurent, Louise C.; Pico, Alexander; Roberts, Lewis R.; Roth, Matthew E.; Rozowsky, Joel S.; Su, Andrew I.; Gerstein, Mark B.; Milosavljevic, Aleksandar
Fonte: Co-Action Publishing Publicador: Co-Action Publishing
Tipo: Artigo de Revista Científica
Publicado em 28/08/2015 Português
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The large diversity and volume of extracellular RNA (exRNA) data that will form the basis of the exRNA Atlas generated by the Extracellular RNA Communication Consortium pose a substantial data integration challenge. We here present the strategy that is being implemented by the exRNA Data Management and Resource Repository, which employs metadata, biomedical ontologies and Linked Data technologies, such as Resource Description Framework to integrate a diverse set of exRNA profiles into an exRNA Atlas and enable integrative exRNA analysis. We focus on the following three specific data integration tasks: (a) selection of samples from a virtual biorepository for exRNA profiling and for inclusion in the exRNA Atlas; (b) retrieval of a data slice from the exRNA Atlas for integrative analysis and (c) interpretation of exRNA analysis results in the context of pathways and networks. As exRNA profiling gains wide adoption in the research community, we anticipate that the strategies discussed here will increasingly be required to enable data reuse and to facilitate integrative analysis of exRNA data.

Information and Communication Technologies for Rural Development : Volume 2. An Evaluation of Telecenters in Indonesia

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Português
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Information and communication technologies (ICTs) are a potentially revolutionary means of empowering the poor. Realizing this potential will require investments that increase access to ICTs in remote low productivity areas and the development of innovative applications that cater to the needs of the poor and small firms. The costs of these kinds of investment have been decreasing rapidly, but still yield low short term private returns. The private sector cannot alone be expected to underwrite the costs of these developments. If Government does not support these public investments, economic disparities will rise, undermining social stability and future growth. Effective public sector action is required, to establish a regulatory and legal framework that enables the rise of a vibrant innovative competitive private telecommunications and ICT services sector, and to institute selective efficient and transparent public subsidies with high social payoff but low financial returns. This is needed most urgently precisely in developing country contexts where public institutions are often ineffective, corrupt and unaccountable. The challenge takes added significance in Indonesia, a country still recovering from severe economic and political crisis...

Survey of ICT and Education in Africa : Ethiopia Country Report

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Português
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This short country report, a result of larger Information for Development Program (infoDev)-supported survey of Information and Communication Technologies (ICT) in education in Africa, provides a general overview of current activities and issues related to ICT use in education in the country. Leapfrogging is the word most technical people would use to describe the advancement, at least in infrastructure, that has occurred in Ethiopia in less than 10 years. Even though the country may still have one of the lowest tele-densities in the continent, there are signs that this situation will soon change. The WoredaNet, the e-government communication backbone, developed by the Ethiopian Telecommunication Corporation, is a promise and a major enabler for rapid ICT development in the country. Already the public sector and the education sector have begun to benefit from this network, and the health and agriculture sectors have been lined up for the next phase. With all this and a corresponding ICT for education policy and implementation plan...

Ghana Country Study : A Roadmap for the Strategic Application of Information and Communication Technology

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Português
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At the end of February 2011, the World Bank commissioned Balancing Act to assess the innovative Information and communication Technologies (ICT) applications already being used in the country, the impact of these applications, and provide recommendations on how these applications could be scaled up in the future. The study is part of a wider World Bank initiative to scale up the strategic application of information and communication technology in Africa. The study takes as its main assumption that ICT can provide a number of different ways that can help the social and economic growth of a country. However, it also looks at the interplay between things that ICT can make happen and the broader factors affecting Ghana. The structure of the report is as follows: 1) creating critical mass - the central argument; 2) the transition from infrastructure to services and applications; 3) the current state of ICT-enabled services and applications in Ghana; and 4) getting from here to there: actions needed to scale-up ICT services and apps. The methodology for this study has three parts to it: an examination of the African ICT roadmap; comparisons with Kenya and other countries; and the gathering of expert opinion both from the public and private sectors.

Spatial Data Infrastructure and INSPIRE

Tonchovska, Rumyana; Stanley, Victoria; De Martino, Samantha
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Português
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35.73%
Spatial Data Infrastructure (SDI) is defined as a framework of policies, institutional arrangements, technologies, data, and people that enables the sharing and effective usage of geographic information by standardizing formats and protocols for access and interoperability. The goals of SDI are to: 1) reduce duplication of efforts among governments, 2) lower costs related to geographic information while making geographic data more accessible, 3) increase the benefits of using available spatial data, and 4) establish key partnerships between states, counties, cities, academia, and the private sector. SDI should be seen as part of wider e- Government initiatives. Infrastructure for Spatial Information in the European Community (INSPIRE) is a European Union (EU) directive that came into force on May 15, 2007, binding EU members to establish a spatial data infrastructure via the Internet that facilitates the sharing of geographic information in a standardized way. INSPIRE addresses technical and nontechnical issues...

Central America : Big Data in Action for Development

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Português
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This report stemmed from a World Bank pilot activity to explore the potential of big data to address development challenges in Central American countries. As part of this activity we collected and analyzed a number of examples of leveraging big data for development. Because of the growing interest in this topic this report makes available to a broader audience those examples as well as the underlying conceptual framework to think about big data for development. To make effective use of big data, many practitioners emphasize the importance of beginning with a question instead of the data itself. A question clarifies the purpose of utilizing big data, whether it is for awareness, understanding, and/or forecasting. In addition, a question suggests the kinds of real-world behaviors or conditions that are of interest. These behaviors are encoded into data through some generating process which includes the media through which behavior is captured. Then various data sources are accessed, prepared, consolidated and analyzed. This ultimately gives rise to insights into the question of interest...

Traffic congestion control in communication networks

Makki, Shamila
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Português
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35.73%
Next generation networks are characterized by ever increasing complexity, intelligence, heterogeneous technologies and increasing user expectations. Telecommunication networks in particular have become truly global, consisting of a variety of national and regional networks, both wired and wireless. Consequently, the management of telecommunication networks is becoming increasingly complex. In addition, network security and reliability requirements require additional overheads which increase the size of the data records. This in turn causes acute network traffic congestions. There is no single network management methodology to control the various requirements of today's networks, and provides a good level of Quality of Service (QoS), and network security. Therefore, an integrated approach is needed in which a combination of methodologies can provide solutions and answers to network events (which cause severe congestions and compromise the quality of service and security). ^ The proposed solution focused on a systematic approach to design a network management system based upon the recent advances in the mobile agent technologies. This solution has provided a new traffic management system for telecommunication networks that is capable of (1) reducing the network traffic load (thus reducing traffic congestion)...

The Distinct Effects of Information Technology and Communication Technology on Firm Organization

Bloom, Nicholas; Garicano, Luis; Sadun, Raffaella; Van Reenen, John
Fonte: INFORMS Publicador: INFORMS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
35.73%
Empirical studies on information communication technologies (ICT) typically aggregate the "information" and "communication" components together. We show theoretically and empirically that this is problematic. Information and communication technologies have very different effects on the decisions taken at each level of an organization. Better information access pushes decisions down, as it allows for superior decentralized decision making without an undue cognitive burden on those lower in the hierarchy. Better communication pushes decisions up, as it allows employees to rely on those above them in the hierarchy to make decisions. Using an original dataset of firms from the U.S. and seven European countries we study the impact of ICT on worker autonomy, plant manager autonomy, and span of control. Consistent with the theory, we find that better information technologies (Enterprise Resource Planning, ERP, for plant managers and CAD/CAM for production workers) are associated with more autonomy and a wider span of control. By contrast, communication technologies (like data networks) decrease autonomy for both workers and plant managers. Treating technology as endogenous using instrumental variables (distance from the birthplace of ERP and heterogeneous telecommunication costs arising from different regulatory regimes) strengthens our results.

Communication Practices in a Distributed Scrum Project

Raety, Petteri; Behm, Benjamin; Dikert, Kim-Karol; Paasivaara, Maria; Lassenius, Casper; Damian, Daniela
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/08/2013 Português
Relevância na Pesquisa
35.73%
While global software development (GSD) projects face cultural and time differences, the biggest challenge is communication. We studied a distributed student project with an industrial customer. The project lasted 3 months, involved 25 participants, and was distributed between the University of Victoria, Canada and Aalto University, Finland. We analyzed email communication, version control system (VCS) data, and surveys on satisfaction. Our aim was to find out whether reflecting on communication affected it, if standups influenced when developers committed to the VCS repository, and if leaders emerged in the three distributed Scrum teams. Initially students sent on average 21 emails per day. With the reduction to 16 emails, satisfaction with communication increased. By comparing Scrum standup times and VCS activity we found that the live communication of standups activated people to work on the project. Out of the three teams, one had an emergent communication facilitator.; Comment: Presented at COINs13 Conference, Chile, 2013 (arxiv:1308.1028)

Networks of digital humanities scholars: The informational and social uses and gratifications of Twitter

Quan-Haase, Anabel; Martin, Kim; McCay-Peet, Lori
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/07/2015 Português
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35.73%
Big data research is currently split on whether and to what extent Twitter can be characterised as an informational or social network. We contribute to this line of inquiry through an investigation of digital humanities scholars' uses and gratifications of Twitter. We conducted a thematic analysis of 25 semistructured interview transcripts to learn about these scholars' professional use of Twitter. Our findings show that Twitter is considered a critical tool for informal communication within DH invisible colleges, functioning at varying levels as both an informational network (learning to 'Twitter' and maintaining awareness) and a social network (imagining audiences and engaging other digital humanists). We find that Twitter follow relationships reflect common academic interests and are closely tied to scholars' preexisting social ties and conference or event co-attendance. The concept of the invisible college continues to be relevant but requires revisiting. The invisible college formed on Twitter is messy, consisting of overlapping social contexts (professional, personal, and public), scholars with different habits of engagement, and both formal and informal ties. Our research illustrates the value of using multiple methods to explore the complex questions arising from big data studies and points toward future research that could implement big data techniques on a small scale...

Scheduling for Stable and Reliable Communication over Multiaccess Channels and Degraded Broadcast Channels

Sayee, K. C. V. Kalyanarama Sesha
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/09/2006 Português
Relevância na Pesquisa
35.73%
Information-theoretic arguments focus on modeling the reliability of information transmission, assuming availability of infinite data at sources, thus ignoring randomness in message generation times at the respective sources. However, in information transport networks, not only is reliable transmission important, but also stability, i.e., finiteness of mean delay incurred by messages from the time of generation to the time of successful reception. Usually, delay analysis is done separately using queueing-theoretic arguments, whereas reliable information transmission is studied using information theory. In this thesis, we investigate these two important aspects of data communication jointly by suitably combining models from these two fields. In particular, we model scheduled communication of messages, that arrive in a random process, (i) over multiaccess channels, with either independent decoding or joint decoding, and (ii) over degraded broadcast channels. The scheduling policies proposed permit up to a certain maximum number of messages for simultaneous transmission. In the first part of the thesis, we develop a multi-class discrete-time processor-sharing queueing model, and then investigate the stability of this queue. In particular...

The Geospatial Characteristics of a Social Movement Communication Network

Conover, Michael D.; Davis, Clayton; Ferrara, Emilio; McKelvey, Karissa; Menczer, Filippo; Flammini, Alessandro
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/06/2013 Português
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35.73%
Social movements rely in large measure on networked communication technologies to organize and disseminate information relating to the movements' objectives. In this work we seek to understand how the goals and needs of a protest movement are reflected in the geographic patterns of its communication network, and how these patterns differ from those of stable political communication. To this end, we examine an online communication network reconstructed from over 600,000 tweets from a thirty-six week period covering the birth and maturation of the American anticapitalist movement, Occupy Wall Street. We find that, compared to a network of stable domestic political communication, the Occupy Wall Street network exhibits higher levels of locality and a hub and spoke structure, in which the majority of non-local attention is allocated to high-profile locations such as New York, California, and Washington D.C. Moreover, we observe that information flows across state boundaries are more likely to contain framing language and references to the media, while communication among individuals in the same state is more likely to reference protest action and specific places and and times. Tying these results to social movement theory, we propose that these features reflect the movement's efforts to mobilize resources at the local level and to develop narrative frames that reinforce collective purpose at the national level.; Comment: Open access available at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0064679

Dynamic stochastic blockmodels: Statistical models for time-evolving networks

Xu, Kevin S.; Hero III, Alfred O.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/04/2013 Português
Relevância na Pesquisa
35.73%
Significant efforts have gone into the development of statistical models for analyzing data in the form of networks, such as social networks. Most existing work has focused on modeling static networks, which represent either a single time snapshot or an aggregate view over time. There has been recent interest in statistical modeling of dynamic networks, which are observed at multiple points in time and offer a richer representation of many complex phenomena. In this paper, we propose a state-space model for dynamic networks that extends the well-known stochastic blockmodel for static networks to the dynamic setting. We then propose a procedure to fit the model using a modification of the extended Kalman filter augmented with a local search. We apply the procedure to analyze a dynamic social network of email communication.