Social Bootstrapping: How Pinterest and Last.fm Social Communities Benefit by Borrowing Links from Facebook

How does one develop a new online community that is highly engaging to each user and promotes social interaction? A number of websites offer friend-finding features that help users bootstrap social networks on the website by copying links from an established network like Facebook or Twitter. This paper quantifies the extent to which such social bootstrapping is effective in enhancing a social experience of the website. First, we develop a stylised analytical model that suggests that copying tends to produce a giant connected component (i.e., a connected community) quickly and preserves properties such as reciprocity and clustering, up to a linear multiplicative factor. Second, we use data from two websites, Pinterest and Last.fm, to empirically compare the subgraph of links copied from Facebook to links created natively. We find that the copied subgraph has a giant component, higher reciprocity and clustering, and confirm that the copied connections see higher social interactions. However, the need for copying diminishes as users become more active and influential. Such users tend to create links natively on the website, to users who are more similar to them than their Facebook friends. Our findings give new insights into understanding how bootstrapping from established social networks can help engage new users by enhancing social interactivity.Comment: Proc. 23rd International World Wide Web Conference (WWW), 201

The evolutionary origins of hierarchy

Hierarchical organization -- the recursive composition of sub-modules -- is ubiquitous in biological networks, including neural, metabolic, ecological, and genetic regulatory networks, and in human-made systems, such as large organizations and the Internet. To date, most research on hierarchy in networks has been limited to quantifying this property. However, an open, important question in evolutionary biology is why hierarchical organization evolves in the first place. It has recently been shown that modularity evolves because of the presence of a cost for network connections. Here we investigate whether such connection costs also tend to cause a hierarchical organization of such modules. In computational simulations, we find that networks without a connection cost do not evolve to be hierarchical, even when the task has a hierarchical structure. However, with a connection cost, networks evolve to be both modular and hierarchical, and these networks exhibit higher overall performance and evolvability (i.e. faster adaptation to new environments). Additional analyses confirm that hierarchy independently improves adaptability after controlling for modularity. Overall, our results suggest that the same force--the cost of connections--promotes the evolution of both hierarchy and modularity, and that these properties are important drivers of network performance and adaptability. In addition to shedding light on the emergence of hierarchy across the many domains in which it appears, these findings will also accelerate future research into evolving more complex, intelligent computational brains in the fields of artificial intelligence and robotics.Comment: 32 page

Social Justice and the Arts

This document is designed to provide a concise, but representative sampling of the many arts programs, projects, networks, and individuals involved in creative, progressive change in their diverse communities. The purpose of this examination is to provide information to enhance the creative work of the Open Buffalo Arts Network as the initiative moves forward. Not meant as an exhaustive list of relevant places to study, this report represents a variety of small and large organizations that are currently addressing issues of justice and opportunity, worker equity, and high road economic development, and similar topics. The programs or policy organizations in this document are arranged by listing first those potentially the most useful to Open Buffalo or like-minded organizations. However, all the programs listed have interest as creative, purposeful, and sometimes “out of the box” ways to advance social justice and the arts

Determinants of Integration and Its Impact on the Economic Success of Immigrants: A Case Study of the Turkish Community in Berlin

Using a new data on 590 Turkish households in Berlin, we investigate the determinants and impact of integration on economic performance. We find that usual suspects such as time spent in Germany and education have positive impact, while networks have no impact on integration. There is strong evidence that political integration and the degree of full integration promote income. Using endogenous switching regression models, we show that local familial networks increase the income of unintegrated migrant groups only, while transnational networks decrease it. We also find that education is more welfare improving for integrated than non-integrated immigrants.integration, economic success, ethnic networks, Turkish migrants