878 research outputs found
Finding influential spreaders from human activity beyond network location
Most centralities proposed for identifying influential spreaders on social
networks to either spread a message or to stop an epidemic require the full
topological information of the network on which spreading occurs. In practice,
however, collecting all connections between agents in social networks can be
hardly achieved. As a result, such metrics could be difficult to apply to real
social networks. Consequently, a new approach for identifying influential
people without the explicit network information is demanded in order to provide
an efficient immunization or spreading strategy, in a practical sense. In this
study, we seek a possible way for finding influential spreaders by using the
social mechanisms of how social connections are formed in real networks. We
find that a reliable immunization scheme can be achieved by asking people how
they interact with each other. From these surveys we find that the
probabilistic tendency to connect to a hub has the strongest predictive power
for influential spreaders among tested social mechanisms. Our observation also
suggests that people who connect different communities is more likely to be an
influential spreader when a network has a strong modular structure. Our finding
implies that not only the effect of network location but also the behavior of
individuals is important to design optimal immunization or spreading schemes
Theories for influencer identification in complex networks
In social and biological systems, the structural heterogeneity of interaction
networks gives rise to the emergence of a small set of influential nodes, or
influencers, in a series of dynamical processes. Although much smaller than the
entire network, these influencers were observed to be able to shape the
collective dynamics of large populations in different contexts. As such, the
successful identification of influencers should have profound implications in
various real-world spreading dynamics such as viral marketing, epidemic
outbreaks and cascading failure. In this chapter, we first summarize the
centrality-based approach in finding single influencers in complex networks,
and then discuss the more complicated problem of locating multiple influencers
from a collective point of view. Progress rooted in collective influence
theory, belief-propagation and computer science will be presented. Finally, we
present some applications of influencer identification in diverse real-world
systems, including online social platforms, scientific publication, brain
networks and socioeconomic systems.Comment: 24 pages, 6 figure
Searching for superspreaders of information in real-world social media
A number of predictors have been suggested to detect the most influential
spreaders of information in online social media across various domains such as
Twitter or Facebook. In particular, degree, PageRank, k-core and other
centralities have been adopted to rank the spreading capability of users in
information dissemination media. So far, validation of the proposed predictors
has been done by simulating the spreading dynamics rather than following real
information flow in social networks. Consequently, only model-dependent
contradictory results have been achieved so far for the best predictor. Here,
we address this issue directly. We search for influential spreaders by
following the real spreading dynamics in a wide range of networks. We find that
the widely-used degree and PageRank fail in ranking users' influence. We find
that the best spreaders are consistently located in the k-core across
dissimilar social platforms such as Twitter, Facebook, Livejournal and
scientific publishing in the American Physical Society. Furthermore, when the
complete global network structure is unavailable, we find that the sum of the
nearest neighbors' degree is a reliable local proxy for user's influence. Our
analysis provides practical instructions for optimal design of strategies for
"viral" information dissemination in relevant applications.Comment: 12 pages, 7 figure
Efficient detection of contagious outbreaks in massive metropolitan encounter networks
Physical contact remains difficult to trace in large metropolitan networks,
though it is a key vehicle for the transmission of contagious outbreaks.
Co-presence encounters during daily transit use provide us with a city-scale
time-resolved physical contact network, consisting of 1 billion contacts among
3 million transit users. Here, we study the advantage that knowledge of such
co-presence structures may provide for early detection of contagious outbreaks.
We first examine the "friend sensor" scheme --- a simple, but universal
strategy requiring only local information --- and demonstrate that it provides
significant early detection of simulated outbreaks. Taking advantage of the
full network structure, we then identify advanced "global sensor sets",
obtaining substantial early warning times savings over the friends sensor
scheme. Individuals with highest number of encounters are the most efficient
sensors, with performance comparable to individuals with the highest travel
frequency, exploratory behavior and structural centrality. An efficiency
balance emerges when testing the dependency on sensor size and evaluating
sensor reliability; we find that substantial and reliable lead-time could be
attained by monitoring only 0.01% of the population with the highest degree.Comment: 4 figure
Spatial super-spreaders and super-susceptibles in human movement networks
As lockdowns and stay-at-home orders start to be lifted across the globe,
governments are struggling to establish effective and practical guidelines to
reopen their economies. In dense urban environments with people returning to
work and public transportation resuming full capacity, enforcing strict social
distancing measures will be extremely challenging, if not practically
impossible. Governments are thus paying close attention to particular locations
that may become the next cluster of disease spreading. Indeed, certain places,
like some people, can be "super-spreaders." Is a bustling train station in a
central business district more or less susceptible and vulnerable as compared
to teeming bus interchanges in the suburbs? Here, we propose a quantitative and
systematic framework to identify spatial super-spreaders and the novel concept
of super-susceptibles, i.e. respectively, places most likely to contribute to
disease spread or to people contracting it. Our proposed data-analytic
framework is based on the daily-aggregated ridership data of public transport
in Singapore. By constructing the directed and weighted human movement networks
and integrating human flow intensity with two neighborhood diversity metrics,
we are able to pinpoint super-spreader and super-susceptible locations. Our
results reveal that most super-spreaders are also super-susceptibles and that
counterintuitively, busy peripheral bus interchanges are riskier places than
crowded central train stations. Our analysis is based on data from Singapore,
but can be readily adapted and extended for any other major urban center. It
therefore serves as a useful framework for devising targeted and cost-effective
preventive measures for urban planning and epidemiological preparedness.Comment: 19 pages, 10 figure
Influence of augmented humans in online interactions during voting events
The advent of the digital era provided a fertile ground for the development
of virtual societies, complex systems influencing real-world dynamics.
Understanding online human behavior and its relevance beyond the digital
boundaries is still an open challenge. Here we show that online social
interactions during a massive voting event can be used to build an accurate map
of real-world political parties and electoral ranks. We provide evidence that
information flow and collective attention are often driven by a special class
of highly influential users, that we name "augmented humans", who exploit
thousands of automated agents, also known as bots, for enhancing their online
influence. We show that augmented humans generate deep information cascades, to
the same extent of news media and other broadcasters, while they uniformly
infiltrate across the full range of identified groups. Digital augmentation
represents the cyber-physical counterpart of the human desire to acquire power
within social systems.Comment: 11 page
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