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Wild Carpathia II

From The Mountains To The Sea, a hymn to Romania’s natural beauty and cultural richness, hailed as the most beautiful cinematic travelogue about Romania.


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Complex World
Cutting Edge Research about Complex Systems
Curated by Claudia Mihai
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How bird flocks are like liquid helium

How bird flocks are like liquid helium | Complex World | Scoop.it

Mathematical model shows how hundreds of starlings coordinate their movements in flight.

A flock of starlings flies as one, a spectacular display in which each bird flits about as if in a well-choreographed dance. Everyone seems to know exactly when and where to turn. Now, for the first time, researchers have measured how that knowledge moves through the flock—a behavior that mirrors certain quantum phenomena of liquid helium.

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Competitive Dynamics on Complex Networks

Competitive Dynamics on Complex Networks | Complex World | Scoop.it
We consider a dynamical network model in which two competitors have fixed and different states, and each normal agent adjusts its state according to a distributed consensus protocol. The state of each normal agent converges to a steady value which is a convex combination of the competitors' states, and is independent of the initial states of agents. This implies that the competition result is fully determined by the network structure and positions of competitors in the network. We compute an Influence Matrix (IM) in which each element characterizing the influence of an agent on another agent in the network. We use the IM to predict the bias of each normal agent and thus predict which competitor will win. Furthermore, we compare the IM criterion with seven node centrality measures to predict the winner. We find that the competitor with higher Katz Centrality in an undirected network or higher PageRank in a directed network is most likely to be the winner. These findings may shed new light on the role of network structure in competition and to what extent could competitors adjust network structure so as to win the competition.
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A simple generative model of collective online behavior

A simple generative model of collective online behavior | Complex World | Scoop.it

One of the most common strategies in studying complex systems is to investigate and interpret whether any “hidden order” is present by fitting observed statistical regularities via data analysis and then reproducing such regularities with long-time or equilibrium dynamics from some generative model. Unfortunately, many different models can possess indistinguishable long-time dynamics, so the above recipe is often insufficient to discern the relative quality of competing models. In this paper, we use the example of collective online behavior to illustrate that, by contrast, time-dependent modeling can be very effective at disentangling competing generative models of a complex system.

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Mathematicians Explain Why Social Epidemics Spread Faster in Some Countries Than Others

Mathematicians Explain Why Social Epidemics Spread Faster in Some Countries Than Others | Complex World | Scoop.it
Psychologists have always puzzled over why people in Sweden were slower to start smoking and slower to stop. Now a group of mathematicians have worked out why.
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Diseases, symptoms, genes, and proteins linked together in giant network

Diseases, symptoms, genes, and proteins linked together in giant network | Complex World | Scoop.it

The first indication that you're sick is typically one or more symptoms: perhaps a cough, fever, abdominal pain, etc. Symptoms are high-level clinical manifestations of a disease that, at a lower level, is caused by molecular-level components, such as genes and proteins. Understanding the complex ways in which symptoms, diseases, and their underlying molecular mechanisms are related can provide a valuable tool for medical researchers when designing better treatments.

However, this area of research is still very new and not well understood. In a new study published in Nature Communications, researchers XueZhong Zhou, et al., have constructed a human symptoms-disease network (HSDN) that reveals the numerous and sometimes surprising connections between symptoms, diseases, genes, and proteins.

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Biologists discover electric bacteria that eat pure electrons rather than sugar

Biologists discover electric bacteria that eat pure electrons rather than sugar | Complex World | Scoop.it

Some intrepid biologists at the University of Southern California (USC) have discovered bacteria that survives on nothing but electricity -- rather than food, they eat and excrete pure electrons. These bacteria yet again prove the almost miraculous tenacity of life -- but, from a technology standpoint, they might also prove to be useful in enabling the creation of self-powered nanoscale devices that clean up pollution. Some of these bacteria also have the curious ability to form into ‘biocables,’ microbial nanowires that are centimeters long and conduct electricity as well as copper wires — a capability that might one day be tapped to build long, self-assembling subsurface networks for human use.

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Information-based fitness and the emergence of criticality in living systems

Information-based fitness and the emergence of criticality in living systems | Complex World | Scoop.it

Recently, evidence has been mounting that biological systems might operate at the borderline between order and disorder, i.e., near a critical point. A general mathematical framework for understanding this common pattern, explaining the possible origin and role of criticality in living adaptive and evolutionary systems, is still missing. We rationalize this apparently ubiquitous criticality in terms of adaptive and evolutionary functional advantages. We provide an analytical framework, which demonstrates that the optimal response to broadly different changing environments occurs in systems organizing spontaneously—through adaptation or evolution—to the vicinity of a critical point. Furthermore, criticality turns out to be the evolutionary stable outcome of a community of individuals aimed at communicating with each other to create a collective entity.

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Romanian cave holds some of the oldest human footprints

Romanian cave holds some of the oldest human footprints | Complex World | Scoop.it

Human footprints found in Romania’s Ciur-Izbuc Cave represent the oldest such impressions in Europe, and perhaps the world, researchers say.

About 400 footprints were first discovered in the cave in 1965. Scientists initially attributed the impressions to a man, woman and child who lived 10,000 to 15,000 years ago. But radiocarbon measurements of two cave bear bones excavated just below the footprints now indicate that Homo sapiens made these tracks around 36,500 years ago, say anthropologist David Webb of Kutztown University in Pennsylvania and his colleagues. Analyses of 51 footprints that remain — cave explorers and tourists have destroyed the rest — indicate that six or seven individuals, including at least one child, entered the cave after a flood had coated its floor with sandy mud, the researchers report July 7 in the American Journal of Physical Anthropology.


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Interaction network based early-warning indicators of vegetation transitions

Interaction network based early-warning indicators of vegetation transitions | Complex World | Scoop.it

Changes in vegetation patterns in semi-arid regions can precede the abrupt transition to bare soil. Here, complex network techniques are used to develop novel early-warning indicators for these desertification transitions. These indicators are applied to results from a local positive feedback vegetation model and are compared to classical indicators, such as the autocorrelation and variance of biomass time series. A quantitative measure is also introduced to evaluate the quality of the early-warning indicators. Based on this measure, the network-based indicators are superior to the classical ones, being more sensitive to the presence of the transition point.

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The Network Structure of Jewish Texts

The Network Structure of Jewish Texts | Complex World | Scoop.it

Sefaria, is an open source database of Jewish texts and recently, Liz Shayne of UC Santa Barbara attempted to extract the relationships between the texts found there—annotations, allusions, and such—and visualize them. Unfortunately, Sefaria is very much a work-in-progress, so conclusions are likely to early to be drawn, but here is a quick visualization that Shayne performed of the complete network of more than 100,000 nodes and 87,000 links

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Jean-Michel Livowsky's curator insight, July 12, 10:28 AM

Une structure neuronale dans l'organisation des textes sacrés ?

Voilà qui me réconcilie avec la religion !

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We need a Github of Science

We need a Github of Science | Complex World | Scoop.it

Summary

Publishing is central to Academia, but its publishing system is outclassed by what Open Source software developers have in GitHub

GitHub’s success is not just about openness, but also a prestige economy that rewards valuable content producers with credit and attention

Open Science efforts like arXiv and PLoS ONE should follow GitHub’s lead and embrace the social web


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Searching for superspreaders of information in real-world social media

Searching for superspreaders of information in real-world social media | Complex World | Scoop.it

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.

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The Strength of the Strongest Ties in Collaborative Problem Solving

The Strength of the Strongest Ties in Collaborative Problem Solving | Complex World | Scoop.it
Complex problem solving in science, engineering, and business has become a highly collaborative endeavor. Teams of scientists or engineers collaborate on projects using their social networks to gather new ideas and feedback. Here we bridge the literature on team performance and information networks by studying teams' problem solving abilities as a function of both their within-team networks and their members' extended networks. We show that, while an assigned team's performance is strongly correlated with its networks of expressive and instrumental ties, only the strongest ties in both networks have an effect on performance. Both networks of strong ties explain more of the variance than other factors, such as measured or self-evaluated technical competencies, or the personalities of the team members. In fact, the inclusion of the network of strong ties renders these factors non-significant in the statistical analysis. Our results have consequences for the organization of teams of scientists, engineers, and other knowledge workers tackling today's most complex problems.
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The Beautiful Phenomena Of Starling Flocks, Explained By Computers

The Beautiful Phenomena Of Starling Flocks, Explained By Computers | Complex World | Scoop.it

On its own, a single starling doesn't elicit much fuss. It's a tennis-ball-sized bird, glossy black in winter, purplish or green in summer, and in autumn, sometimes speckled with white spots. But when starlings congregate in flocks of hundreds of thousands over open fields (something scientists call a "murmuration") they pitch and arc and rush at one another in a bizarre choreography that's puzzled naturalists for hundreds of years. A whole catalog of YouTube videos has documented the black shapes in flight, a movement that looks like the birds are attached to a giant rhythmic gymnast's invisible ribbon.

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The Science of Problem Solving

The Science of Problem Solving | Complex World | Scoop.it
A review of the science behind problem solving, how it functions in the brain and how we can do it better.
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Exploring No Man’s Sky, A Computer Game Forged by Algorithms

Exploring No Man’s Sky, A Computer Game Forged by Algorithms | Complex World | Scoop.it
A new computer game, No Man’s Sky, demonstrates a new way to build computer games filled with diverse flora and fauna.

Sean Murray, one of the creators of the computer game No Man’s Sky, can’t guarantee that the virtual universe he is building is infinite, but he’s certain that, if it isn’t, nobody will ever find out. “If you were to visit one virtual planet every second,” he says, “then our own sun will have died before you’d have seen them all.”

No Man’s Sky is a video game quite unlike any other. Developed for Sony’s PlayStation 4 by an improbably small team (the original four-person crew has grown only to 10 in recent months) at Hello Games, an independent studio in the south of England, it’s a game that presents a traversable universe in which every rock, flower, tree, creature, and planet has been “procedurally generated” to create a vast and diverse play area.

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Prevalence and use of Twitter among scholars

Prevalence and use of Twitter among scholars | Complex World | Scoop.it
Prevalence and use of Twitter among scholars (Infographic on Prevalence and use of Twitter among scholars
http://t.co/skulthbeMe)
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Fat-Tailed Fluctuations in the Size of Organizations: The Role of Social Influence

Fat-Tailed Fluctuations in the Size of Organizations: The Role of Social Influence | Complex World | Scoop.it

Organizational growth processes have consistently been shown to exhibit a fatter-than-Gaussian growth-rate distribution in a variety of settings. Long periods of relatively small changes are interrupted by sudden changes in all size scales. This kind of extreme events can have important consequences for the development of biological and socio-economic systems. Existing models do not derive this aggregated pattern from agent actions at the micro level. We develop an agent-based simulation model on a social network. We take our departure in a model by a Schwarzkopf et al. on a scale-free network. We reproduce the fat-tailed pattern out of internal dynamics alone, and also find that it is robust with respect to network topology. Thus, the social network and the local interactions are a prerequisite for generating the pattern, but not the network topology itself. We further extend the model with a parameter  that weights the relative fraction of an individual's neighbours belonging to a given organization, representing a contextual aspect of social influence. In the lower limit of this parameter, the fraction is irrelevant and choice of organization is random. In the upper limit of the parameter, the largest fraction quickly dominates, leading to a winner-takes-all situation. We recover the real pattern as an intermediate case between these two extremes.

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Understanding the group dynamics and success of teams

Understanding the group dynamics and success of teams | Complex World | Scoop.it

Tackling complex problems often requires coordinated group effort and can consume significant resources, yet our understanding of how teams form and succeed has been limited by a lack of large scale, quantitative data. We analyze activity traces and success levels for ∼150,000 self-organized, online team projects. While larger teams tend to be more successful, the distribution of activity is highly skewed across the team, with only small subsets of members performing most work. This
focused centralization in activity indicates that larger teams succeed not simply by distributing workload, but by acting as a support system for a smaller set of core members. High impact teams are significantly more focused than average teams of the same size, yet are more likely to consist of members with diverse experiences, and these members, even non-core members, are more likely to themselves be core members of other teams. This mixture of size, focus, experience, and diversity points to underlying mechanisms that can be used to maximize the success of collaborative endeavors.

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A genetic epidemiology approach to cyber-security

A genetic epidemiology approach to cyber-security | Complex World | Scoop.it
While much attention has been paid to the vulnerability of computer networks to node and link failure, there is limited systematic understanding of the factors that determine the likelihood that a node (computer) is compromised.
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The 1% of scientific publishing

The 1% of scientific publishing | Complex World | Scoop.it
Only a handful of researchers manage to publish one or more papers per year
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Jean-Michel Livowsky's curator insight, July 18, 3:40 PM

Pourquoi le 1 %...

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Beyond Word Frequency: Bursts, Lulls, and Scaling in the Temporal Distributions of Words

Beyond Word Frequency: Bursts, Lulls, and Scaling in the Temporal Distributions of Words | Complex World | Scoop.it
Background

Zipf's discovery that word frequency distributions obey a power law established parallels between biological and physical processes, and language, laying the groundwork for a complex systems perspective on human communication. More recent research has also identified scaling regularities in the dynamics underlying the successive occurrences of events, suggesting the possibility of similar findings for language as well.

Methodology/Principal Findings

By considering frequent words in USENET discussion groups and in disparate databases where the language has different levels of formality, here we show that the distributions of distances between successive occurrences of the same word display bursty deviations from a Poisson process and are well characterized by a stretched exponential (Weibull) scaling. The extent of this deviation depends strongly on semantic type – a measure of the logicality of each word – and less strongly on frequency. We develop a generative model of this behavior that fully determines the dynamics of word usage.

Conclusions/Significance

Recurrence patterns of words are well described by a stretched exponential distribution of recurrence times, an empirical scaling that cannot be anticipated from Zipf's law. Because the use of words provides a uniquely precise and powerful lens on human thought and activity, our findings also have implications for other overt manifestations of collective human dynamics.

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Rescooped by Claudia Mihai from Non-Equilibrium Social Science
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Connecting Core Percolation and Controllability of Complex Networks

Connecting Core Percolation and Controllability of Complex Networks | Complex World | Scoop.it
Core percolation is a fundamental structural transition in complex networks related to a wide range of important problems. Recent advances have provided us an analytical framework of core percolation in uncorrelated random networks with arbitrary degree distributions. Here we apply the tools in analysis of network controllability. We confirm analytically that the emergence of the bifurcation in control coincides with the formation of the core and the structure of the core determines the control mode of the network. We also derive the analytical expression related to the controllability robustness by extending the deduction in core percolation. These findings help us better understand the interesting interplay between the structural and dynamical properties of complex networks.

Via Shaolin Tan, Alejandro J. Alvarez S., Tim Williamson, NESS
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Sibout Nooteboom's curator insight, July 13, 12:52 AM

Fascinating advances

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The scaling of human interactions with city size

The scaling of human interactions with city size | Complex World | Scoop.it

The size of cities is known to play a fundamental role in social and economic life. Yet, its relation to the structure of the underlying network of human interactions has not been investigated empirically in detail. In this paper, we map society-wide communication networks to the urban areas of two European countries. We show that both the total number of contacts and the total communication activity grow superlinearly with city population size, according to well-defined scaling relations and resulting from a multiplicative increase that affects most citizens. Perhaps surprisingly, however, the probability that an individual’s contacts are also connected with each other remains largely unaffected. These empirical results predict a systematic and scale-invariant acceleration of interaction-based spreading phenomena as cities get bigger, which is numerically confirmed by applying epidemiological models to the studied networks. Our findings should provide a microscopic basis towards understanding the superlinear increase of different socioeconomic quantities with city size, that applies to almost all urban systems and includes, for instance, the creation of new inventions or the prevalence of certain contagious diseases.

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Experimental evidence of massive-scale emotional contagion through social networks

Experimental evidence of massive-scale emotional contagion through social networks | Complex World | Scoop.it

We show, via a massive (N = 689,003) experiment on Facebook, that emotional states can be transferred to others via emotional contagion, leading people to experience the same emotions without their awareness. We provide experimental evidence that emotional contagion occurs without direct interaction between people (exposure to a friend expressing an emotion is sufficient), and in the complete absence of nonverbal cues.

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