SNA

1 Questo contributo presenta i primi risultati di un progetto tuttora in corso sul potenziale della SNA in archeologia con particolare riferimento all'emergere delle società complesse e delle identità etniche nell'Italia centrale durante il Primo Ferro e le età successive. In particolare, questa prima fase del progetto è stata completata grazie a un periodo di ricerca e insegnamento svolto al Graduate Centre for the Study of Culture (GCSC) della Justus Leibig Universität in Giessen (Germania), nel semestre estivo del 2009, e poi a un soggiorno di ricerca al Netherlands In-

n this paper we introduce a new model to represent an interconnected network of networks. This model is fundamental to reason about the real organization of on-line social networks, where users belong to and interact on different networks at the same time. In addition we extend traditional SNA measures to deal with this multiplicity of networks and we apply the model to a real dataset extracted from two microblogging sites.

Abstract In this article we question a central trope of transnationalism and new media – deterritorialization – and its application to border crossing Internet usage by Iranian and Turkish-Kurdish migrants in the Netherlands. Their Internet usage indicates the extent to which territoriality channels these groups' online practice. We found Dutch-Iranian sites reflected correspondingly sparse offline community networks and state boundaries moulded their transnational ties, while regionally specific transnational dynamics were evident in Turkish-Kurdish website surfing. These cases indicate that transnationalism and new media need not broaden or dissolve geographical identity or connectivity, but may reinforce it. Finally, we address the relations of territoriality with generation (first and second) and network medium (web forums versus conventional sites). Whereas first-generation migrants' life online often reveals extensions of offline networks, the online practice of the second generation frequently reflects these networks in subtler ways, forming partially sovereign online communities that pivot on hyphenated identities. However, the relations of generation and network medium differ for Turkish Kurds and Iranians in the Netherlands.

While distrust and divisiveness amongst Iranians in different
diaspora environments have been commonly acknowledged,
there are additional indications suggesting that Dutch-
Iranian organizations are relatively scarce. In this article, we
compare the organizational networks of Dutch-Iranians to
those of Turks and Moroccans in the Netherlands. The results
show that organization density is lower and fragmentation
higher for Dutch-Iranians. We explain this by Iranian
forms of organization, which have been transplanted to and
interact with the diaspora. However, Dutch-Iranians are
also exceptionally well integrated in the Dutch society. This
puts the relationship between integration and ethnic organization
into question.

Given the importance of relationships to civil society, many scholars have positioned strategic communication as essential to the civil society process. Using social network analysis, this study extends relationship management theory into the civil society arena and offers implications on how network approaches to examining relationships may help to move the theory forward. Using data gathered from a network of Peruvian civil society organizations, the article theoretically and methodologically links relationship management theory with social network perspectives, and the results of the study are discussed in terms of their contributions to extending relationship management theory and civil society research. Critiques of social network analysis and implications for its use in strategic communication research and theory development are also explored.

The public by default nature of Twitter messages, together with the adoption of the #hashtag convention led, in few years, to the creation of a digital space able to host worldwide conversation on almost every kind of topic. From major TV shows to Natural disasters there is no contemporary event that does not have its own #hashtag to gather together the ongoing Twitter conversation. These topical discussions take place outside of the Twitter network made of followers and friends. Nevertheless this topical network is where many of the most studied phenomena take place. Therefore Twitter based communication exists on two almost autonomous levels: the Twitter network made of followers and friends that shows a certain level of stability and the topical network, characterized by a high level of contingency, that appears and disappears following the rhythm of a worldwide conversation. Despite the fact that this double nature of Twitter is widely recognized among scholars there is still little literature facing the relationships between these two networks. This paper presents the results of an empirical research aimed at discovering how the Twitter network is affected by what happens on the topical network. Does the participation in the same hashtag based conversation change the follower list of the participants? Is it possible to point out specific social behaviors that would produce a major gain of followers? Our conclusions are based on real data concerning the popular TV show Xfactor, that largely used Twitter as the official backchannel platform for its audience. * This work has been partly funded by FIRB project Information monitoring, propagation analysis and community detection in social network sites and PRIN project Relazioni sociali ed identità in Rete: vissuti e narrazioni degli italiani nei siti di social network

Background

Living systems are associated with Social networks — networks made up of nodes, some of which may be more important in various aspects as compared to others. While different quantitative measures labeled as “centralities” have previously been used in the network analysis community to find out influential nodes in a network, it is debatable how valid the centrality measures actually are. In other words, the research question that remains unanswered is: how exactly do these measures perform in the real world? So, as an example, if a centrality of a particular node identifies it to be important, is the node actually important?

Purpose

The goal of this paper is not just to perform a traditional social network analysis but rather to evaluate different centrality measures by conducting an empirical study analyzing exactly how do network centralities correlate with data from published multidisciplinary network data sets.

Method

We take standard published network data sets while using a random network to establish a baseline. These data sets included the Zachary's Karate Club network, dolphin social network and a neural network of nematode Caenorhabditis elegans. Each of the data sets was analyzed in terms of different centrality measures and compared with existing knowledge from associated published articles to review the role of each centrality measure in the determination of influential nodes.

Results

Our empirical analysis demonstrates that in the chosen network data sets, nodes which had a high Closeness Centrality also had a high Eccentricity Centrality. Likewise high Degree Centrality also correlated closely with a high Eigenvector Centrality. Whereas Betweenness Centrality varied according to network topology and did not demonstrate any noticeable pattern. In terms of identification of key nodes, we discovered that as compared with other centrality measures, Eigenvector and Eccentricity Centralities were better able to identify important nodes.

Transnational Dutch-Iranian hyperlink networks allow the exploration of relationships between virtual and physical space. According to many of its analysts, the Internet implies a virtual transcendence of place, but ethnographic approaches have convincingly redirected attention to issues of embeddedness. Here, this concept principally applies to national contexts of hyperlink production, content, and directionality. This article examines the interrelationships of on-line and off-line contexts (patterns of Dutch-Iranian communal organization) as a prelude to explorations of transnational hyperlinking. My findings indicate that national hyperlinks remain relatively important and that transnational links, far from being ‘deterritorialized’, follow national patterns for their sectoral distribution. That is, physical space, of nation-state boundaries in particular, weighs heavily on virtual interaction.

Studies of the Dutch-Iranian diaspora are rare, but all indicate features
that set it apart from other migrant communities in the Netherlands. It appears
from these surveys that Dutch-Iranians have low levels of communal organization
and sparsely knit networks. This article maintains that the pattern also holds for
online Dutch-Iranian community structures, and builds its case on an examination
of hyperlinks between websites of Iranians in the Netherlands. Second, the
article examines sectors and their mutual relations in online Dutch-Iranian
networks. It is argued, against what may be deduced from established theory and
observations of Iranian diasporas, that networks organized around cultural
content are the most inclusive and central and those which centre upon politics,
the most exclusive and isolated. Linking patterns as well as website content serve
to lay bare this structure of hyperlinked Dutch-Iranian cyberspace.

The public by default nature of Twitter messages, together with the adoption of the #hashtag convention led, in few years, to the creation of a digital space able to host world- wide conversation on almost every kind of topic. From ma- jor TV shows to Natural disasters there is no contemporary event that does not have its own #hashtag to gather together the ongoing Twitter conversation. These topical discussions take place outside of the Twitter network made of followers and friends. Nevertheless this topical network is where many of the most studied phenomena take place. Therefore Twitter based communication exists on two almost autonomous lev- els: the Twitter network made of followers and friends that shows a certain level of stability and the topical network, characterized by a high level of contingency, that appears and disappears following the rhythm of a worldwide conversation.
Despite the fact that this double nature of Twitter is widely recognized among scholars there is still little literature fac- ing the relationships between these two networks. This paper presents the results of an empirical research aimed at discov- ering how the Twitter network is affected by what happens on the topical network. Does the participation in the same hash- tag based conversation change the follower list of the par- ticipants? Is it possible to point out specific social behaviors that would produce a major gain of followers? Our conclu- sions are based on real data concerning the popular TV show Xfactor, that largely used Twitter as the official backchannel platform for its audience.

In this paper we introduce a new model to represent an interconnected network of networks. This model is fundamental to reason about the real organization of on-line social networks, where users belong to and interact on different networks at the same time. In addition we extend traditional SNA measures to deal with this multiplicity of networks and we apply the model to a real dataset extracted from two microblogging sites.

The public by default nature of Twitter messages, together with the adoption of the #hashtag convention led, in few years, to the creation of a digital space able to host worldwide conversation on almost every kind of topic. From major TV shows to Natural disasters there is no contemporary event that does not have its own #hashtag to gather together the ongoing Twitter conversation. These topical discussions take place outside of the Twitter network made of followers and friends. Nevertheless this topical network is where many of the most studied phenomena take place. Therefore Twitter based communication exists on two almost autonomous levels: the Twitter network made of followers and friends that shows a certain level of stability and the topical network, characterized by a high level of contingency, that appears and disappears following the rhythm of a worldwide conversation. Despite the fact that this double nature of Twitter is widely recognized among scholars there is still little literature facing the relationships between these two networks. This paper presents the results of an empirical research aimed at discovering how the Twitter network is affected by what happens on the topical network. Does the participation in the same hashtag based conversation change the follower list of the participants? Is it possible to point out specific social behaviors that would produce a major gain of followers? Our conclusions are based on real data concerning the popular TV show Xfactor, that largely used Twitter as the official backchannel platform for its audience. * This work has been partly funded by FIRB project Information monitoring, propagation analysis and community detection in social network sites and PRIN project Relazioni sociali ed identità in Rete: vissuti e narrazioni degli italiani nei siti di social network

The characteristics of several issues, such as ICT infrastructure, learning objects, multimedia effects, way of teaching and tutoring, and interaction among the participants, all affect the quality of an e-learning system, though their impact varies accordingly with the specific e-learning system analysed. The object of our analysis is the e-learning system used in the on-line courses offered by the School of Engineering in the University of Rome "Tor Vergata". The success of this system is mainly based on a deep level of interaction among instructors and students, mostly through the use of on-line forums, which allow both discussions related to the learning process (including class notes, homework, and assessments) as well as favour the social cohesion of the classrooms, thus improving the students' own rate of learning. In this paper, we present the results of a DSS prototype that focus on such aspects of on-line interaction and discuss the lessons learned from its first development.

The rapid increase of the bandwidth demand have led to the growth of optical communications which are used for implementing not only backbones but also access networks. Due to the sensitivity of the applications relying on optical networks, security becomes a major concern. The paper evaluates the performance of the optical firewall proposed in [6] which is able to protect Optical Burst Switched (OBS) networks against physical layer attacks. We first describe the architecture of the optical firewall. Then, we present the design of the BHP (Burst Header Packet) waiting module which is the main component of the optical firewall architecture. Finally, we propose a simulation of the waiting module in order to evaluate the performance of the firewall.

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6149836

This article examines the relationship between structural location (namely, degree centrality) and news media coverage. Our central hypothesis is that the network centrality of social movement actors is positively associated with the prevalence of actors being cited in the print news media. This paper uses two-mode data from a communication network of environmentalists in British Columbia, and examines the relationship between their structural location and the frequency by which they are cited in newsprint media with regard to particular frames (about forest conservation, environmental protest, and related issues). We asked a sample of social movement participants about their ties to a target list of relatively high profile actors (environmental activists). We turned the resulting network matrix into a bipartite graph that examined the relationships amongst the target actors vis a vis the respondents. Next we calculated point in-degree for the target actors. For the target actors we also have data from a representative sample of 957 print news articles about forestry and conservation of old growth forests in British Columbia. We compare the effects of network centrality of the target actor versus several attributes of the target actors (gender, level of radicalism, leadership status) on the amount of media coverage that each of the target actors receives. We find that network centrality is associated with media coverage controlling for actor attributes. We discuss theoretical implications of this research. Finally, we also discuss the methodological pros and cons of using a "target name roster" to construct two-mode data on social movement activists.