5,171 research outputs found
The reachability of contagion in temporal contact networks: how disease latency can exploit the rhythm of human behavior
The symptoms of many infectious diseases influence their host to withdraw
from social activity limiting their own potential to spread. Successful
transmission therefore requires the onset of infectiousness to coincide with a
time when its host is socially active. Since social activity and infectiousness
are both temporal phenomena, we hypothesize that diseases are most pervasive
when these two processes are synchronized. We consider disease dynamics that
incorporate a behavioral response that effectively shortens the infectious
period of the disease. We apply this model to data collected from face-to-face
social interactions and look specifically at how the duration of the latent
period effects the reachability of the disease. We then simulate the spread of
the model disease on the network to test the robustness of our results.
Diseases with latent periods that synchronize with the temporal social behavior
of people, i.e. latent periods of 24 hours or 7 days, correspond to peaks in
the number of individuals who are potentially at risk of becoming infected. The
effect of this synchronization is present for a range of disease models with
realistic parameters. The relationship between the latent period of an
infectious disease and its pervasiveness is non-linear and depends strongly on
the social context in which the disease is spreading.Comment: 9 Pages, 5 figure
Measuring and Modeling Information Flow on Social Networks
With the rise of social media, researchers have become increasingly interested in understanding how individuals inform, influence, and interact with others in their social network and how the network mediates the flow of information. Previous research on information flow has primarily used models of contagion to study the adoption of a technology, propagation of purchase recommendations, or virality of online activity. Social (or complex ) contagions spread differently than biological ( simple ) contagions. A limitation when researchers validate contagion models is that they neglect much of the massive amounts of data now available through online social networks. Here we model a recently proposed information-theoretic approach to measuring the flow of written information in data. We use an idealized generative model for text data -- the quoter model -- which naturally incorporates this measure. We investigate how network structure impacts information flow and find that the quoter model exhibits interesting features similar to those of complex contagion. Finally, we offer an analytical treatment of the quoter model: we derive approximate calculations and show dependence on model parameters. This thesis gives rise to new hypotheses about the role of the social network in facilitating information flow, which future research can investigate using real-world data
Contextual Centrality: Going Beyond Network Structures
Centrality is a fundamental network property which ranks nodes by their
structural importance. However, structural importance may not suffice to
predict successful diffusions in a wide range of applications, such as
word-of-mouth marketing and political campaigns. In particular, nodes with high
structural importance may contribute negatively to the objective of the
diffusion. To address this problem, we propose contextual centrality, which
integrates structural positions, the diffusion process, and, most importantly,
nodal contributions to the objective of the diffusion. We perform an empirical
analysis of the adoption of microfinance in Indian villages and weather
insurance in Chinese villages. Results show that contextual centrality of the
first-informed individuals has higher predictive power towards the eventual
adoption outcomes than other standard centrality measures. Interestingly, when
the product of diffusion rate and the largest eigenvalue is
larger than one and diffusion period is long, contextual centrality linearly
scales with eigenvector centrality. This approximation reveals that contextual
centrality identifies scenarios where a higher diffusion rate of individuals
may negatively influence the cascade payoff. Further simulations on the
synthetic and real-world networks show that contextual centrality has the
advantage of selecting an individual whose local neighborhood generates a high
cascade payoff when . Under this condition, stronger homophily
leads to higher cascade payoff. Our results suggest that contextual centrality
captures more complicated dynamics on networks and has significant implications
for applications, such as information diffusion, viral marketing, and political
campaigns
Non-consensus opinion model on directed networks
Dynamic social opinion models have been widely studied on undirected
networks, and most of them are based on spin interaction models that produce a
consensus. In reality, however, many networks such as Twitter and the World
Wide Web are directed and are composed of both unidirectional and bidirectional
links. Moreover, from choosing a coffee brand to deciding who to vote for in an
election, two or more competing opinions often coexist. In response to this
ubiquity of directed networks and the coexistence of two or more opinions in
decision-making situations, we study a non-consensus opinion model introduced
by Shao et al. \cite{shao2009dynamic} on directed networks. We define
directionality as the percentage of unidirectional links in a network,
and we use the linear correlation coefficient between the indegree and
outdegree of a node to quantify the relation between the indegree and
outdegree. We introduce two degree-preserving rewiring approaches which allow
us to construct directed networks that can have a broad range of possible
combinations of directionality and linear correlation coefficient
and to study how and impact opinion competitions. We find that, as
the directionality or the indegree and outdegree correlation
increases, the majority opinion becomes more dominant and the minority
opinion's ability to survive is lowered
Using Text Similarity to Detect Social Interactions not Captured by Formal Reply Mechanisms
In modeling social interaction online, it is important to understand when
people are reacting to each other. Many systems have explicit indicators of
replies, such as threading in discussion forums or replies and retweets in
Twitter. However, it is likely these explicit indicators capture only part of
people's reactions to each other, thus, computational social science approaches
that use them to infer relationships or influence are likely to miss the mark.
This paper explores the problem of detecting non-explicit responses, presenting
a new approach that uses tf-idf similarity between a user's own tweets and
recent tweets by people they follow. Based on a month's worth of posting data
from 449 ego networks in Twitter, this method demonstrates that it is likely
that at least 11% of reactions are not captured by the explicit reply and
retweet mechanisms. Further, these uncaptured reactions are not evenly
distributed between users: some users, who create replies and retweets without
using the official interface mechanisms, are much more responsive to followees
than they appear. This suggests that detecting non-explicit responses is an
important consideration in mitigating biases and building more accurate models
when using these markers to study social interaction and information diffusion.Comment: A final version of this work was published in the 2015 IEEE 11th
International Conference on e-Science (e-Science
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