Technical University of Denmark
The Scales of Human Mobility
May 25, 2021 @ 7:20 EST, 12:20 BST, 13:20 CEST
There is a contradiction at the heart of our current understanding of mobility patterns. On one hand, a highly influential stream of literature driven by analyses of massive empirical datasets finds that human movements show no evidence of characteristic spatial scales. There, human mobility is described as scale-free. On the other hand, in geography, the concept of scale, referring to meaningful levels of description from individual buildings through neighborhoods, cities, regions, and countries, is central. Here, we resolve this apparent paradox by showing that human mobility does indeed contain meaningful scales, corresponding to spatial containers restricting mobility behavior. The scale-free results arise from aggregating displacements across containers. We present a simple model, which given a person’s trajectory, infers their neighborhoods, cities and so on. We find that the containers characterizing the trajectories of more than 700,000 individuals worldwide do indeed have typical sizes. We show that our description improves on the state-of-the-art in modeling, and allows us to better understand effects due to socio-demographic differences and the built environment.
University of Vermont, USA
Exploring the OCEAN: Open source Complex Ecosystems and Networks
May 26, 2021 @ 11:10 EST, 16:10 BST, 17:10 CEST
s open source has taken over much of software development, GitHub has become the central online platform for most open source code repositories. With this popularity, the digital traces of GitHub are now a valuable means to study teamwork and collaboration. In this talk, I will discuss projects that leverage these data to understand the properties of successful teams and how individuals collaborate across teams. A significant portion of the non-coding work necessary to support open source, such as organizing conferences or providing outreach, often goes unrecognized, so we study how individuals and automated systems acknowledge different contributions to projects. In many ways, GitHub is a convenience sample. We need to assess its representativeness, particularly how Github is used and how its design may alter the working patterns of its users. We develop a novel, nearly-complete sample of open source project repositories outside of centralized platforms like GitHub. Compared to GitHub, these projects tend to have more collaborators, are maintained for longer periods, and tend to be more focused on academic and scientific problems.
University of Pennsylvania, USA
The Curious Human
May 24, 2021 @ 9:00 EST, 14:00 BST, 15:00 CEST
The human mind is curious. It is strange, remarkable, and mystifying; it is eager, probing, questioning. Despite its pervasiveness and its relevance for our well-being, scientific studies of human curiosity that bridge both the organ of curiosity and the object of curiosity remain in their infancy. In this talk, I will integrate historical, philosophical, and psychological perspectives with techniques from applied mathematics and statistical physics to study individual and collective curiosity. In the former, I will evaluate how humans walk on the knowledge network of Wikipedia during unconstrained browsing. In doing so, we will capture idiosyncratic forms of curiosity that span multiple millennia, cultures, languages, and timescales. In the latter, I will consider the fruition of collective curiosity in the building of scientific knowledge as encoded in Wikipedia. Throughout, I will make a case for the position that individual and collective curiosity are both network building processes, providing a connective counterpoint to the common acquisitional account of curiosity in humans.
Northeastern University, USA
#HashtagActivism: Networks of Race and Gender Justice
May 26, 2021 @ 9:00 EST, 14:00 BST, 15:00 CEST
The proliferation of social media has given rise to widespread study and speculation about the impact of digital technologies on politics, activism, and social change. Key among these debates is the role social media play in shaping the contemporary public sphere, and by proxy, our societies. Maligned by some as “slacktivism,” I will argue social media platforms such as Twitter create unique opportunities for often-excluded voices to challenge the terms of public debate. Using the evidence from Twitter hashtag networks such as #BlackLivesMatter and #MeToo, I will demonstrate how hashtag activism complements other forms of activism to change the terms of mainstream public debates about race and gender justice in the United States.
This talk is based on my book #HashtagActivism (co-authored with Sarah J. Jackson and Moya Bailey), which is available for free download from MIT Press direct.
Cornell University, USA
Consensus and Discord in Models of Opinion Formation
May 25, 2021 @ 9:00 EST, 14:00 BST, 15:00 CEST
A long line of work in the mathematical social sciences has considered models of opinion formation in which agents in a network hold opinions drawn from a one-dimensional space, and update their opinions based on different forms of averaging with the opinions of their neighbors. We consider two broad themes in these models: first, the contrast between equilibrium opinions and notions of social optimality; and second, the potential for an adversary to perturb the dynamics with the goal of causing discord. For both of these categories of questions, we show how the underlying behavior is governed by eigenvalues of the network structure. In contrast to typical applications of spectral analysis for networks, where only the extreme eigenvalues determine the outcome, we find here that the entire set of eigenvalues plays an intrinsic role in the dynamics. This talk is based on joint work with David Bindel, Jason Gaitonde, Sigal Oren, and Eva Tardos.
UN World Food Programme
Mapping socio-economic vulnerabilities with non-traditional data and predictive modeling
May 24, 2021 @ 7:20 EST, 12:20 BST, 13:20 CEST
In a rapidly changing world, severely affected by extreme weather events, epidemic outbreaks, economic shocks and conflicts, it is of fundamental importance to understand where the most vulnerable people are, how many they are, and to identify what it is that makes them more vulnerable than others to these threats. During the last decade, research has shown that data such as digital traces, phone metadata and satellite imagery carry relevant information beyond their original purpose and can be used as a proxy to measure socio-economic characteristics and detect vulnerabilities when traditional data is not available. Following an overview of these studies, the talk will deep dive into the UN World Food Programme’s original work on predicting and mapping food security. We will then conclude by discussing challenges and limitations, but also opportunities, that come with these approaches.