Search results for " Centrality"
showing 10 items of 37 documents
An Efficient Immunization Strategy Using Overlapping Nodes and Its Neighborhoods
2018
International audience; When an epidemic occurs, it is often impossible to vaccinate the entire population due to limited amount of resources. Therefore, it is of prime interest to identify the set of influential spreaders to immunize, in order to minimize both the cost of vaccine resource and the disease spreading. While various strategies based on the network topology have been introduced, few works consider the influence of the community structure in the epidemic spreading process. Nowadays, it is clear that many real-world networks exhibit an overlapping community structure, in which nodes are allowed to belong to more than one community. Previous work shows that the numbers of communit…
Evaluating the structure and use of hiking trails in recreational areas using a mixed GPS tracking and graph theory approach
2014
Abstract Recreational trails encourage numerous outdoor leisure activities in a variety of urban, rural, and natural environments. Understanding the way trails function is crucial for the designers and managers of recreational sites to balance the needs of visitors and site capacities. This paper presents a new approach to evaluate the structure and use of hiking trails by combining GPS tracking and analytical methods based on graph theory. The study is based upon empirical data (N = 482 GPS tracks) collected in the Lobau, which is part of the Danube Floodplains National Park in Austria. The physical structure of trails (structural network; undirected graph) and their usage (functional netw…
Archimedean actions on median pretrees
2001
In this paper we consider group actions on generalized treelike structures (termed ‘pretrees’) defined simply in terms of betweenness relations. Using a result of Levitt, we show that if a countable group admits an archimedean action on a median pretree, then it admits an action by isometries on an [open face R]-tree. Thus the theory of isometric actions on [open face R]-trees may be extended to a more general setting where it merges naturally with the theory of right-orderable groups. This approach has application also to the study of convergence group actions on continua.
Resistant Microbial Cooccurrence Patterns Inferred by Network Topology
2015
ABSTRACT Although complex cooccurrence patterns have been described for microbes in natural communities, these patterns have scarcely been interpreted in the context of ecosystem functioning and stability. Here we constructed networks from species cooccurrences between pairs of microorganisms which were extracted from five individual aquatic time series, including a dystrophic and a eutrophic lake as well as an open ocean site. The resulting networks exhibited higher clustering coefficients, shorter path lengths, and higher average node degrees and levels of betweenness than those of random networks. Moreover, simulations demonstrated that taxa with a large number of cooccurrences and place…
Seeking the Important Nodes of Complex Networks in Product R&D Team Based on Fuzzy AHP and TOPSIS
2013
Published version of article in the journal: Mathematical Problems in Engineering. Alo available from the publisher at: http://dx.doi.org/10.1155/2013/327592 Open Access How to seek the important nodes of complex networks in product research and development (R&D) team is particularly important for companies engaged in creativity and innovation. The previous literature mainly uses several single indicators to assess the node importance; this paper proposes a multiple attribute decision making model to tentatively solve these problems. Firstly, choose eight indicators as the evaluation criteria, four from centralization of complex networks: degree centrality, betweenness centrality, closeness…
Peripheral Centralities: An Integrated Approach
2017
Un profondo cambiamento caratterizza a livello globale gli insediamenti urbani: ciò può essere osservato attraverso le relazioni tra centro e periferie. Le aree periferiche sono il banco dove il futuro delle città può essere opportunamente messo alla prova, in cui è possibile prefigurare la futura qualità della vita di individui e comunità. Sicurezza, sostenibilità, benessere che potranno essere raggiunti nelle aree periferiche saranno più rilevanti in termini quantitativi; invece il senso di identificazione e appartenenza, più forte nelle aree centrali, è debole o assente nelle periferie. Occorre puntare quindi a una sorta di centralità diffusa, applicando un approccio integrato, che si ad…
Disrupting resilient criminal networks through data analysis: The case of Sicilian Mafia
2020
Compared to other types of social networks, criminal networks present hard challenges, due to their strong resilience to disruption, which poses severe hurdles to law-enforcement agencies. Herein, we borrow methods and tools from Social Network Analysis to (i) unveil the structure of Sicilian Mafia gangs, based on two real-world datasets, and (ii) gain insights as to how to efficiently disrupt them. Mafia networks have peculiar features, due to the links distribution and strength, which makes them very different from other social networks, and extremely robust to exogenous perturbations. Analysts are also faced with the difficulty in collecting reliable datasets that accurately describe the…
‘Too interconnected to fail’ financial network of US CDS market: Topological fragility and systemic risk
2012
A small segment of credit default swaps (CDS) on residential mortgage backed securities (RMBS) stand implicated in the 2007 financial crisis. The dominance of a few big players in the chains of insurance and reinsurance for CDS credit risk mitigation for banks' assets has led to the idea of too interconnected to fail (TITF) resulting, as in the case of AIG, of a tax payer bailout. We provide an empirical reconstruction of the US CDS network based on the FDIC Call Reports for off balance sheet bank data for the 4th quarter in 2007 and 2008. The propagation of financial contagion in networks with dense clustering which reflects high concentration or localization of exposures between few parti…
Le «31 biblioteche più belle del mondo». Dalla Real Biblioteca del Monasterio de San Lorenzo de El Escorial di Madrid al trasferimento, nella nuova s…
2021
Gabriella De Marco propone un saggio sulla centralità dell'istituzione biblioteca nella società contemporanea. Il contributo, che prosegue alcuni precedenti progetti di ricerca avviati dall'autrice sin dai primi anni duemila, è centrato sullo spazio abitabile e sul potenziale identitario di un edificio. Punto di partenza del suo ragionamento è il presupposto che lo spazio misurabile è anche spazio mentale. Ciò attiva una serie di considerazioni legate al rapporto tra il tempo della storia e il tempo del fruitore. Un edificio, pertanto, e nello specifico una biblioteca sia pubblica o privata sia nazionale o di quartiere, si percepisce ed esiste anche nel tempo soggettivo di chi la fruisce.
Beyond Border Binaries: Borderlines, Borderlands, and In-Betweenness in Thomas King’s Short Story “Borders”
2011
The concerns at the border in the late twentieth and early twenty-first centuries are not so much goods and customs any longer but establishing the identity and citizenship of those crossing the line. This focus increased further after 9/11 with new security concerns and the ensuing thickening of the Canada–US border. With the mother, one of the protagonists in Thomas King’s short story “Borders,” insisting on her Blackfoot identity, she and her son are stuck in the middle. They can neither go back to Canada nor cross the border into the United States. Quite literally, they are stranded in what Homi K. Bhabha called “third space.” The setting of the duty-free store, located “between the two…