Complex World
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Complex World
Cutting Edge Research about Complex Systems
Curated by Claudia Mihai
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Entropy and order in urban street networks

Entropy and order in urban street networks | Complex World | Scoop.it

Many complex networks erase parts of their geometry as they develop, so that their evolution is difficult to quantify and trace. Here we introduce entropy measures for quantifying the complexity of street orientations and length variations within planar networks and apply them to the street networks of 41 British cities, whose geometric evolution over centuries can be explored. The results show that the street networks of the old central parts of the cities have lower orientation/length entropies - the streets are more tightly ordered and form denser networks - than the outer and more recent parts. Entropy and street length increase, because of spreading, with distance from the network centre. Tracing the 400-year evolution of one network indicates growth through densification (streets are added within the existing network) and expansion (streets are added at the margin of the network) and a gradual increase in entropy over time.

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System of Systems

If you look at our planet from space, what you see is something like a neural network with the cities as its nodes, and that is as good an image of the planet as a complex system of systems as one could hope for.

With the emergence of the internet in the mid-90's, the world became one global commons. In the past, we could understand that there was some mysterious unity to the various dimensions of life but we couldn't understand its dynamics, we couldn't observe and measure their interactions. We basically operated like the drunk who looks under the streetlight for his keys because that's where he can see.

 

Video featuring, from IBM: Mike Wing, Irving Wladawsky-Berger and Julia Grace.


Via NESS
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Feynman on Scientific Method.

Physicist Richard Feynman explains the scientific and unscientific methods of understanding nature.
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Imagining the Future City: London 2062

Imagining the Future City: London 2062 | Complex World | Scoop.it

As part of the UCL Grand Challenge of Sustainable Cities, the London 2062 project is gathering evidence about the forces and factors that shape London, identifying decision points, and debating how the city will change over the five decades between London 2012 and London 2062. This process involves synthesising the diverse expertise within the academic community at UCL and elsewhere, together with London’s citizens, government, professions, artists, media and other public institutions.

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luiy's curator insight, December 3, 2013 8:47 AM

Imagining the Future City: London 2062 (free download) is an edited collection based on the London 2062 project from UCL’s Grand Challenge of Sustainable Cities. The London 2062 project engaged academics, policy makers and practitioners, providing a forum for serious debate about the challenges and opportunities for London in the five decades following the Olympics.


The book is divided into four sections, considering London in terms of Things, Connections, Powerand Dreams. The book features contributions from leading academic thinkers at UCL and from those involved in shaping London on the ground, through policy and practice. The authors consider the future of London from multiple viewpoints, including transport, energy, smart infrastructure, water, population, housing and the economy.

 

The aim of this book, and the London 2062 programme, is to open discussion about the future of London. What is the future we want to see for London? Which priorities for a global city are in opposition? How can we meet carbon emission targets and deliver new infrastructure in the 21st Century?

Intriguing Networks's curator insight, December 8, 2013 5:58 PM

LONDON CALLING - How will you influence the shape of your city get involved folks! Thank you @plevy

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Emergence of network features from multiplexity

Emergence of network features from multiplexity | Complex World | Scoop.it

Many biological and man-made networked systems are characterized by the simultaneous presence of different sub-networks organized in separate layers, with links and nodes of qualitatively different types. While during the past few years theoretical studies have examined a variety of structural features of complex networks, the outstanding question is whether such features are characterizing all single layers, or rather emerge as a result of coarse-graining, i.e. when going from the multilayered to the aggregate network representation. Here we address this issue with the help of real data. We analyze the structural properties of an intrinsically multilayered real network, the European Air Transportation Multiplex Network in which each commercial airline defines a network layer. We examine how several structural measures evolve as layers are progressively merged together. In particular, we discuss how the topology of each layer affects the emergence of structural properties in the aggregate network.

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Ali Anani's curator insight, November 23, 2013 3:30 AM
A solid approach to the understanding of complex networks
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Slaying dragon-kings could prevent financial crashes

Slaying dragon-kings could prevent financial crashes | Complex World | Scoop.it
The first suppression of an extreme event called a dragon-king suggests we may one day be able to avert some financial crashes, brain seizures and storms
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Correlations in the population structure of music, genes and language

Correlations in the population structure of music, genes and language | Complex World | Scoop.it

Abstract: We present, to our knowledge, the first quantitative evidence that music and genes may have coevolved by demonstrating significant correlations between traditional group-level folk songs and mitochondrial DNA variation among nine indigenous populations of Taiwan. These correlations were of comparable magnitude to those between language and genes for the same populations, although music and language were not significantly correlated with one another. An examination of population structure for genetics showed stronger parallels to music than to language. Overall, the results suggest that music might have a sufficient time-depth to retrace ancient population movements and, additionally, that it might be capturing different aspects of population history than language. Music may therefore have the potential to serve as a novel marker of human migrations to complement genes, language and other markers.

 
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A Solution to the Challenge of Optimization on ''Golf-Course''-Like Fitness Landscapes

A Solution to the Challenge of Optimization on ''Golf-Course''-Like Fitness Landscapes | Complex World | Scoop.it

Genetic algorithms (GAs) have been used to find efficient solutions to numerous fundamental and applied problems. While GAs are a robust and flexible approach to solve complex problems, there are some situations under which they perform poorly. Here, we introduce a genetic algorithm approach that is able to solve complex tasks plagued by so-called ''golf-course''-like fitness landscapes. Our approach, which we denote variable environment genetic algorithms (VEGAs), is able to find highly efficient solutions by inducing environmental changes that require more complex solutions and thus creating an evolutionary drive. Using the density classification task, a paradigmatic computer science problem, as a case study, we show that more complex rules that preserve information about the solution to simpler tasks can adapt to more challenging environments. Interestingly, we find that conservative strategies, which have a bias toward the current state, evolve naturally as a highly efficient solution to the density classification task under noisy conditions.

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Lyme bacteria show that evolvability is evolvable

Lyme bacteria show that evolvability is evolvable | Complex World | Scoop.it

Some gamblers succeed by spiriting cards up their sleeves, giving them a wider range of hands to play. So do some bacteria, whose great capacity for genetic variability helps them evolve and adapt to rapidly changing environments.

There are other data that suggest that there could be selection on evolvability, but this is the first example where there really aren’t any other confounding answers for the data,” says lead author Dustin Brisson, an evolutionary biologist at the University of Pennsylvania in Philadelphia

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Time lapse map of every nuclear explosion ever on Earth

Time lapse map of every nuclear explosion ever on Earth | Complex World | Scoop.it

Japanese artist Isao Hashimoto has created a beautiful, undeniably scary time-lapse map of the 2053 nuclear explosions which have taken place between 1945 and 1998, beginning with the Manhattan Project’s “Trinity” test near Los Alamos and concluding with Pakistan’s nuclear tests in May of 1998. This leaves out North Korea’s two alleged nuclear tests in this past decade (the legitimacy of both of which is not 100% clear).

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Quality versus quantity of social ties in experimental cooperative networks

Quality versus quantity of social ties in experimental cooperative networks | Complex World | Scoop.it

Recent studies suggest that allowing individuals to choose their partners can help to maintain cooperation in human social networks; this behaviour can supplement behavioural reciprocity, whereby humans are influenced to cooperate by peer pressure. However, it is unknown how the rate of forming and breaking social ties affects our capacity to cooperate. Here we use a series of online experiments involving 1,529 unique participants embedded in 90 experimental networks, to show that there is a ‘Goldilocks’ effect of network dynamism on cooperation. When the rate of change in social ties is too low, subjects choose to have many ties, even if they attach to defectors. When the rate is too high, cooperators cannot detach from defectors as much as defectors re-attach and, hence, subjects resort to behavioural reciprocity and switch their behaviour to defection. Optimal levels of cooperation are achieved at intermediate levels of change in social ties.

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Experimental evidence for the influence of group size on cultural complexity

Experimental evidence for the influence of group size on cultural complexity | Complex World | Scoop.it

The remarkable ecological and demographic success of humanity is largely attributed to our capacity for cumulative culture1, 2, 3. The accumulation of beneficial cultural innovations across generations is puzzling because transmission events are generally imperfect, although there is large variance in fidelity. Events of perfect cultural transmission and innovations should be more frequent in a large population4. As a consequence, a large population size may be a prerequisite for the evolution of cultural complexity4, 5, although anthropological studies have produced mixed results6, 7, 8, 9 and empirical evidence is lacking10. Here we use a dual-task computer game to show that cultural evolution strongly depends on population size, as players in larger groups maintained higher cultural complexity. We found that when group size increases, cultural knowledge is less deteriorated, improvements to existing cultural traits are more frequent, and cultural trait diversity is maintained more often. Our results demonstrate how changes in group size can generate both adaptive cultural evolution and maladaptive losses of culturally acquired skills. As humans live in habitats for which they are ill-suited without specific cultural adaptations11, 12, it suggests that, in our evolutionary past, group-size reduction may have exposed human societies to significant risks, including societal collapse13.

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The Phylogeny of Little Red Riding Hood

The Phylogeny of Little Red Riding Hood | Complex World | Scoop.it

Researchers have long been fascinated by the strong continuities evident in the oral traditions associated with different cultures. According to the ‘historic-geographic’ school, it is possible to classify similar tales into “international types” and trace them back to their original archetypes. However, critics argue that folktale traditions are fundamentally fluid, and that most international types are artificial constructs. Here, these issues are addressed using phylogenetic methods that were originally developed to reconstruct evolutionary relationships among biological species, and which have been recently applied to a range of cultural phenomena. The study focuses on one of the most debated international types in the literature: ATU 333, ‘Little Red Riding Hood’. A number of variants of ATU 333 have been recorded in European oral traditions, and it has been suggested that the group may include tales from other regions, including Africa and East Asia. However, in many of these cases, it is difficult to differentiate ATU 333 from another widespread international folktale, ATU 123, ‘The Wolf and the Kids’. To shed more light on these relationships, data on 58 folktales were analysed using cladistic, Bayesian and phylogenetic network-based methods. The results demonstrate that, contrary to the claims made by critics of the historic-geographic approach, it is possible to identify ATU 333 and ATU 123 as distinct international types. They further suggest that most of the African tales can be classified as variants of ATU 123, while the East Asian tales probably evolved by blending together elements of both ATU 333 and ATU 123. These findings demonstrate that phylogenetic methods provide a powerful set of tools for testing hypotheses about cross-cultural relationships among folktales, and point towards exciting new directions for research into the transmission and evolution of oral narratives

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Spectral redemption: Finding the hidden groupings in networks

Spectral redemption: Finding the hidden groupings in networks | Complex World | Scoop.it

A persistent problem for mathematicians trying to understand the structures of networks – in datasets representing relationships among everything from galaxies to people – is community detection: finding groups of related data points, or nodes. A network that contains three groups of nodes is fundamentally different from a network that contains two groups. 

“If you’re looking at who eats whom in a food web, you need to understand how groups of predators depend on groups of prey. In an epidemic model, you need to know how fast a disease will spread in one community and how likely it is for it to cross to another community,” says SFI Professor Cris Moore. 

In a paper published this week in PNAS, Moore and collaborators at UC Berkeley and in Paris offer a twist on past approaches to cluster detection that seems to address weaknesses that traditional techniques have in dealing with sparse data — networks where most nodes have just a few links.

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Percolation in multiplex networks with overlap

Percolation in multiplex networks with overlap | Complex World | Scoop.it

From transportation networks to complex infrastructures, and to social and communication networks, a large variety of systems can be described in terms of multiplexes formed by a set of nodes interacting through different networks (layers). Multiplexes may display an increased fragility with respect to the single layers that constitute them. However, so far the overlap of the links in different layers has been mostly neglected, despite the fact that it is an ubiquitous phenomenon in most multiplexes. Here, we show that the overlap among layers can improve the robustness of interdependent multiplex systems and change the critical behavior of the percolation phase transition in a complex way.

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Quantum Light Harvesting Hints at Entirely New Form of Computing

Quantum Light Harvesting Hints at Entirely New Form of Computing | Complex World | Scoop.it

Physicists have long known that plants and bacteria convert light into chemical energy in a way that is hugely efficient. But only in recent years have they discovered that the molecular machines behind this process rely on quantum mechanics to do the job.That’s a big surprise because of the temperatures involved. Quantum states are highly fragile—sneeze and they disappear in a puff of smoke. Physicists can maintain these states for some time in carefully controlled environments at low temperature, but nobody can explain how it can be possible in the warm wet environments inside living things.


Via Alin Velea
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Putting the Wolfram Language (and Mathematica) on Every Raspberry Pi

Putting the Wolfram Language (and Mathematica) on Every Raspberry Pi | Complex World | Scoop.it

Last week I wrote about our large-scale plan to use new technology we’re building to inject sophisticated computation and knowledge into everything. Today I’m pleased toannounce a step in that direction: working with the Raspberry Pi Foundation, effective immediately there’s a pilot release of the Wolfram Language—as well as Mathematica—that will soon be bundled as part of the standard system software for every Raspberry Pi computer.

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Universal Law of Commuting Discovered in African, European and US Mobile Phone Data

Universal Law of Commuting Discovered in African, European and US Mobile Phone Data | Complex World | Scoop.it
Commuters in Africa, Europe and the US all follow the same fundamental pattern of travel between work and home, confirming a theory first suggested 20 years ago.
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Reproducibility: The risks of the replication drive

Reproducibility: The risks of the replication drive | Complex World | Scoop.it
The push to replicate findings could shelve promising research and unfairly damage the reputations of careful, meticulous scientists, says Mina Bissell.
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Complexity, bifurcations, catastrophe

Complexity, bifurcations, catastrophe | Complex World | Scoop.it

What makes a system complex?
It is a perplexing problem--both its description and its quantification. One might think that the description of a system as complex would suggest it has many subsystems each acting in accordance with its own rules, and interacting with each of the other subsystems in ways that we find difficult to describe. But there are systems involving very few "parts" which exhibit the kind of behaviour we call complex.


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Chaotic physics in ferroelectrics hints at brain-like computing

Chaotic physics in ferroelectrics hints at brain-like computing | Complex World | Scoop.it

Unexpected behavior in ferroelectric materials explored by researchers at the Department of Energy's Oak Ridge National Laboratory supports a new approach to information storage and processing. Ferroelectric materials are known for their ability to spontaneously switch polarization when an electric field is applied. Using a scanning probe microscope, the ORNL-led team took advantage of this property to draw areas of switched polarization called domains on the surface of a ferroelectric material. To the researchers' surprise, when written in dense arrays, the domains began forming complex and unpredictable patterns on the material's surface. "When we reduced the distance between domains, we started to see things that should have been completely impossible," said ORNL's Anton Ievlev, the first author on the paper published in Nature Physics. "All of a sudden, when we tried to draw a domain, it wouldn't form, or it would form in an alternating pattern like a checkerboard. At first glance, it didn't make any sense. We thought that when a domain forms, it forms. It shouldn't be dependent on surrounding domains."


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Bursts of Active Transport in Living Cells

Bursts of Active Transport in Living Cells | Complex World | Scoop.it

Abstract: We show, using a large new data set, that the temporally resolved speed of active cargo transport in living cells follows a scaling law over several decades of time and length. The statistical regularities display a time-averaged shape that we interpret to reflect stress buildup, followed by rapid release. The scaling power law agrees quantitatively with those reported in inanimate systems (jammed colloids and granular media, and magnetic Barkhausen noise), suggesting a common origin in pushing through a crowded environment in a weak force regime. The implied regulation of the speed of active cellular transport due to environmental obstruction results in bursts of speed and acceleration. These findings extend the classical notion of molecular crowding.

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Finally, a Way to Predict a Wildfire's Behavior in Real Time: Scientific American

Finally, a Way to Predict a Wildfire's Behavior in Real Time: Scientific American | Complex World | Scoop.it

Scientists have developed a new technique to predict the behavior of wildfires, using high-resolution satellite imagery to periodically check and revise computer simulations.

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Human opinion dynamics: An inspiration to solve complex optimization problems

Human opinion dynamics: An inspiration to solve complex optimization problems | Complex World | Scoop.it
Human interactions give rise to the formation of different kinds of opinions in a society. The study of formations and dynamics of opinions has been one of the most important areas in social physics.

Via Shaolin Tan, Eric L Berlow
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António F Fonseca's curator insight, December 28, 2013 7:14 AM

Another paper on opinion dynamics.

Luciano Lampi's curator insight, January 11, 2014 5:45 PM

Humanrithms....

Claude Emond's curator insight, January 20, 2014 5:51 PM

Opinions are an unescapable part of sharing and influencing the direction of collective intelligence

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Forget The 50 States; The U.S. Is Really 11 Nations

Forget The 50 States; The U.S. Is Really 11 Nations | Complex World | Scoop.it

For hundreds of years, this nation has been known as the United States of America. But according to author and journalist Colin Woodard, the country is neither united, nor made up of 50 states. Woodward has studied American voting patterns, demographics and public opinion polls going back to the days of the first settlers, and says that his research shows America is really made up of 11 different nations.

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