A mechanistic model of connector hubs, modularity, and cognition

The human brain network is modular--comprised of communities of tightly interconnected nodes. This network contains local hubs, which have many connections within their own communities, and connector hubs, which have connections diversely distributed across communities. A mechanistic understanding of these hubs and how they support cognition has not been demonstrated. Here, we leveraged individual differences in hub connectivity and cognition. We show that a model of hub connectivity accurately predicts the cognitive performance of 476 individuals in four distinct tasks. Moreover, there is a general optimal network structure for cognitive performance--individuals with diversely connected hubs and consequent modular brain networks exhibit increased cognitive performance, regardless of the task. Critically, we find evidence consistent with a mechanistic model in which connector hubs tune the connectivity of their neighbors to be more modular while allowing for task appropriate information integration across communities, which increases global modularity and cognitive performance

The Physics of Communicability in Complex Networks

A fundamental problem in the study of complex networks is to provide quantitative measures of correlation and information flow between different parts of a system. To this end, several notions of communicability have been introduced and applied to a wide variety of real-world networks in recent years. Several such communicability functions are reviewed in this paper. It is emphasized that communication and correlation in networks can take place through many more routes than the shortest paths, a fact that may not have been sufficiently appreciated in previously proposed correlation measures. In contrast to these, the communicability measures reviewed in this paper are defined by taking into account all possible routes between two nodes, assigning smaller weights to longer ones. This point of view naturally leads to the definition of communicability in terms of matrix functions, such as the exponential, resolvent, and hyperbolic functions, in which the matrix argument is either the adjacency matrix or the graph Laplacian associated with the network. Considerable insight on communicability can be gained by modeling a network as a system of oscillators and deriving physical interpretations, both classical and quantum-mechanical, of various communicability functions. Applications of communicability measures to the analysis of complex systems are illustrated on a variety of biological, physical and social networks. The last part of the paper is devoted to a review of the notion of locality in complex networks and to computational aspects that by exploiting sparsity can greatly reduce the computational efforts for the calculation of communicability functions for large networks.Comment: Review Article. 90 pages, 14 figures. Contents: Introduction; Communicability in Networks; Physical Analogies; Comparing Communicability Functions; Communicability and the Analysis of Networks; Communicability and Localization in Complex Networks; Computability of Communicability Functions; Conclusions and Prespective

Assessment of the Role of Micro-credit in the Development of Social Capital : A Field Study about Micro-credit Programme Clients in Bangladesh

The aim of the study is to investigate how does the micro-credit does, small scale loans to poor people, work in poverty alleviation and building social capital in rural Bangladesh. The major objective of the study is to show how the NGO activities help to increase women's access to micro-finance, generate new income earning opportunities, and to enhance social mobilization and create formal network, norms and trust for collective action and thus develop social capital. The empirical study is conducted in Bangladesh to assess the increase of women's economic opportunity, security and empowerment and their effect on poverty and changes in the traditional rural social structure. Based on both qualitative and quantitative survey research, the study has organized in-depth interviews and focus group discussion with the programme clients of the two NGOs in Bangladesh. The findings suggest that, microcredit and its supportive programs have lead to a remarkable enhancement in social network formation and development, an improved status in family and community, increased mobility and to some extent also greater self-confidence and feeling of identity for the women. It also has given space to establish and strengthen social ties that reach beyond their familia networks. This process has been nurtured by NGO membership norms at the centre building. Emboldened with the awareness of self-identity beyond kinship ties, women then began to build a collective identity with an extra-familial "face to face" effective group beyond her small locality. These self-identified components of social capital have expanded each woman's life options and introduced new social opportunities for the group. Interaction at the centre has graduated into new and strengthened networks while mobility has given each woman a socially sanctioned license to move about the village and, therefore, the opportunity to call on and continue to build her networks. Perhaps, social implications of micro-credit lending system are more powerful than the economic implications. Sustainable economic and social prosperity seems to be cultivated by regular and frequent interaction and have enabled women to continue to prosper through trust and community cooperation networks long after the initial acquisition of financial capital. The collective nature of group lending NGO style has proved it's far reaching implications on rural women's ability to build social capita

Information technology and social cohesion : a tale of two villages

Acknowledgements This research was made possible by a grant from the EPSRC “Dot.Rural Digital Economy Hub” (EP/G066051/1) at the University of Aberdeen and EPSRC Communities and Culture Network+ (EP/K003585/1).Peer reviewedPostprin

Transnational Activism in Support of National Protest: Questions of Identity and Organization

This article considers the question of whether transnational activism supporting national protest attains a cohesive collective identity on social media whilst organizationally remaining localized. It examines a corpus of social media data collected in the course of two months of rolling protests in 2013 against the largest proposed open-cast gold mine at Roşia Montană, Romania, which echoed among Romanian expatriates. A network text analysis of the data supplemented with interview findings revealed concerns with protest logistics as common across the transnational networks of protest localities on both Facebook and Twitter, a finding that testified to the coordinated character of the protests. On the other hand, collective identity emerged as the fruit of attempts to surmount localized protest experiences of geographically disparate but civically-minded social media users