Search results for " CENTRALITY"
showing 10 items of 37 documents
[Spanish medical center collaboration on smoking research from 1999 through 2003 according to the Science Citation Index].
2007
OBJECTIVE To analyze the network structure of collaboration between medical centers sharing authorship of scientific articles on smoking. MATERIAL AND METHODS Articles reporting smoking research by authors from 2 or more Spanish medical centers between 1999 and the end of 2003 were identified through the Science Citation Index. The network of collaboration behind the research was analyzed and the most important measures of centrality were compared. To display the data, scientometric maps were constructed using UCINET and NETDRAW network analysis tools. RESULTS Thirty-five Spanish medical centers (29 hospitals and 6 health care clinics) in 8 autonomous communities were involved in 21 collabo…
Image Segmentation by Deep Community Detection Approach
2017
International audience; To address the problem of segmenting an image into homogeneous communities this paper proposes an efficient algorithm to detect deep communities in the image by maximizing at each stage a new centrality measure, called the local Fiedler vector centrality (LFVC). This measure is associated with the sensitivity of algebraic connectivity to node removals. We show that a greedy node removal strategy, based on iterative maximization of LFVC, has bounded performance loss relative to the optimal, but intractable, combinatorial batch removal strategy. A remarkable feature of this method is the ability to segments the image automatically into homogeneous regions by maximizing…
Optimal Local Routing Strategies for Community Structured Time Varying Communication Networks
2017
International audience; In time varying data communication networks (TVCN), traffic congestion, system utility maximization and network performance enhancement are the prominent issues. All these issues can be resolved either by optimizing the network structure or by selecting efficient routing approaches. In this paper, we focus on the design of a time varying network model and propose an algorithm to find efficient user route in this network. Centrality plays a very important role in finding congestion free routes. Indeed, the more a node is central, the more it can be congested by the flow coming from or going to its neighborhood. For that reason, classically, routes are chosen such that…
Epidemic diffusion of social updates in Dunbar-based DOSN
2014
Distributed Online Social Networks (DOSNs) do not rely on a central repository for storing social data so that the users can keep control of their private data and do not depend on the social network provider. The ego network, i.e. the network made up of an individual, the ego, along with all the social ties she has with other people, the alters, may be exploited to define distributed social overlays and dissemination protocols. In this paper we propose a new epidemic protocol able to spread social updates in Dunbar-based DOSN overlays where the links between nodes are defined by considering the social interactions between users. Our approach is based on the notion of Weighted Ego Betweenne…
Correlation based networks of equity returns sampled at different time horizons
2006
We investigate the planar maximally filtered graphs of the portfolio of the 300 most capitalized stocks traded at the New York Stock Exchange during the time period 2001-2003. Topological properties such as the average length of shortest paths, the betweenness and the degree are computed on different planar maximally filtered graphs generated by sampling the returns at different time horizons ranging from 5 min up to one trading day. This analysis confirms that the selected stocks compose a hierarchical system progressively structuring as the sampling time horizon increases. Finally, a cluster formation, associated to economic sectors, is quantitatively investigated.
From limit to centrality. Regeneration of the Genoa's port area through architectural and urban design
2012
This survey’s core is the case study of the regeneration of the port area and of the urban waterfront of the city of Genoa, as an emblematic example where the architectural and urban design plays an important role, oriented to the transformation of the port area and to the modification of the relationship that exists between the harbour and the city. In particular this will deepen the possibility, to reverse the condition of limit that characterizes the port area into a new centrality, through the design, passing by intermediate steps that redefine the modalities of access and of connection between city and port, breaking the condition of isolation that ports usually present. As a matter of…
Prevention of Violence against Children and Psychosocial Models of Intervention: Network Analysis of an Inter-Institutional Service
2014
This study describes an Italian service, the Inter-institutional Groups Operating against child Abuse and Maltreatment (GOIAM), which specializes in the treatment of child abuse. The GOIAM service is composed of 53 professionals divided into four different categories: social workers, psychologists, child neuropsychiatrists, and psychopedagogists. With the aim of detecting strengths and weaknesses of the operative model adopted by GOIAM, the whole service was analyzed through the application of social network analysis (SNA). The analysis revealed a low-density network, while the study of centrality yielded different distributions of power indicators (degree, closeness, and betweenness): pres…
The Whole Is Greater than the Sum of the Parts: A Multilayer Approach on Criminal Networks
2022
Traditional social network analysis can be generalized to model some networked systems by multilayer structures where the individual nodes develop relationships in multiple layers. A multilayer network is called multiplex if each layer shares at least one node with some other layer. In this paper, we built a unique criminal multiplex network from the pre-trial detention order by the Preliminary Investigation Judge of the Court of Messina (Sicily) issued at the end of the Montagna anti-mafia operation in 2007. Montagna focused on two families who infiltrated several economic activities through a cartel of entrepreneurs close to the Sicilian Mafia. Our network possesses three layers which sha…
Impact of centrality on cooperative processes
2016
The solution of today's complex problems requires the grouping of task forces whose members are usually connected remotely over long physical distances and different time zones. Hence, understanding the effects of imposed communication patterns (i.e., who can communicate with whom) on group performance is important. Here, we use an agent-based model to explore the influence of the betweenness centrality of the nodes on the time the group requires to find the global maxima of NK-fitness landscapes. The agents cooperate by broadcasting messages, informing on their fitness to their neighbors, and use this information to copy the more successful agents in their neighborhood. We find that for ea…
Correlations among Game of Thieves and other centrality measures in complex networks
2021
Social Network Analysis (SNA) is used to study the exchange of resources among individuals, groups, or organizations. The role of individuals or connections in a network is described by a set of centrality metrics which represent one of the most important results of SNA. Degree, closeness, betweenness and clustering coefficient are the most used centrality measures. Their use is, however, severely hampered by their computation cost. This issue can be overcome by an algorithm called Game of Thieves (GoT). Thanks to this new algorithm, we can compute the importance of all elements in a network (i.e. vertices and edges), compared to the total number of vertices. This calculation is done not in…