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Fathers bequeath more mutations as they age

Fathers bequeath more mutations as they age | Papers | Scoop.it

(...) a study published in Nature finds that the age at which a father sires children determines how many mutations those offspring inherit2. By starting families in their thirties, forties and beyond, men could be increasing the chances that their children will develop autism, schizophrenia and other diseases often linked to new mutations.

 

Fathers bequeath more mutations as they age
Genome study may explain links between paternal age and conditions such as autism.

Ewen Callaway

Nature 488, 439 (23 August 2012) http://dx.doi.org/10.1038/488439a

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The Rise of Social Bots

The Turing test asked whether one could recognize the behavior of a human from that of a computer algorithm. Today this question has suddenly become very relevant in the context of social media, where text constraints limit the expressive power of humans, and real incentives abound to develop human-mimicking software agents called social bots. These elusive entities wildly populate social media ecosystems, often going unnoticed among the population of real people. Bots can be benign or harmful, aiming at persuading, smearing, or deceiving. Here we discuss the characteristics of modern, sophisticated social bots, and how their presence can endanger online ecosystems and our society. We then discuss current efforts aimed at detection of social bots in Twitter. Characteristics related to content, network, sentiment, and temporal patterns of activity are imitated by bots but at the same time can help discriminate synthetic behaviors from human ones, yielding signatures of engineered social tampering.


The Rise of Social Bots
Emilio Ferrara, Onur Varol, Clayton Davis, Filippo Menczer, Alessandro Flammini

http://arxiv.org/abs/1407.5225

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Limits of Predictability in Commuting Flows in the Absence of Data for Calibration

The estimation of commuting flows at different spatial scales is a fundamental problem for different areas of study. Many current methods rely on parameters requiring calibration from empirical trip volumes. Their values are often not generalizable to cases without calibration data. To solve this problem we develop a statistical expression to calculate commuting trips with a quantitative functional form to estimate the model parameter when empirical trip data is not available. We calculate commuting trip volumes at scales from within a city to an entire country, introducing a scaling parameter alpha to the recently proposed parameter free radiation model. The model requires only widely available population and facility density distributions. The parameter can be interpreted as the influence of the region scale and the degree of heterogeneity in the facility distribution. We explore in detail the scaling limitations of this problem, namely under which conditions the proposed model can be applied without trip data for calibration. On the other hand, when empirical trip data is available, we show that the proposed model's estimation accuracy is as good as other existing models. We validated the model in different regions in the U.S., then successfully applied it in three different countries.


Limits of Predictability in Commuting Flows in the Absence of Data for Calibration
Yingxiang Yang, Carlos Herrera, Nathan Eagle, Marta C. Gonzalez

http://arxiv.org/abs/1407.6256

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Short-range interaction vs long-range correlation in bird flocks

We use the maximum entropy method to study how the strength of effective alignment between birds depends on distance. We find in all analyzed flocks that the interaction decays exponentially. Such short-range form is noteworthy, considering that the velocity correlation that is input of the calculation is long-ranged. We use our method to study the directional anisotropy in the alignment interaction and find that the interaction strength along the direction of motion is weaker than in the transverse direction, which may account for the anisotropic spatial distribution of birds observed in natural flocks.


Short-range interaction vs long-range correlation in bird flocks
Andrea Cavagna, Lorenzo Del Castello, Supravat Dey, Irene Giardina, Stefania Melillo, Leonardo Parisi, Massimiliano Viale

http://arxiv.org/abs/1407.6887

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Friendship and natural selection

More than any other species, humans form social ties to individuals who are neither kin nor mates, and these ties tend to be with similar people. Here, we show that this similarity extends to genotypes. Across the whole genome, friends’ genotypes at the single nucleotide polymorphism level tend to be positively correlated (homophilic). In fact, the increase in similarity relative to strangers is at the level of fourth cousins. However, certain genotypes are also negatively correlated (heterophilic) in friends. And the degree of correlation in genotypes can be used to create a “friendship score” that predicts the existence of friendship ties in a hold-out sample. A focused gene-set analysis indicates that some of the overall correlation in genotypes can be explained by specific systems; for example, an olfactory gene set is homophilic and an immune system gene set is heterophilic, suggesting that these systems may play a role in the formation or maintenance of friendship ties. Friends may be a kind of “functional kin.” Finally, homophilic genotypes exhibit significantly higher measures of positive selection, suggesting that, on average, they may yield a synergistic fitness advantage that has been helping to drive recent human evolution.


Friendship and natural selection
Nicholas A. Christakis and James H. Fowler

PNAS

http://dx.doi.org/10.1073/pnas.1400825111


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Christine Capra's curator insight, July 27, 5:06 PM

So, how does this impact our ability to have meaningful exchanges across diverse populations? 

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Coaction versus reciprocity in continuous-time models of cooperation

Cooperating animals frequently show closely coordinated behaviours organized by a continuous flow of information between interacting partners. Such real-time coaction is not captured by the iterated prisoner׳s dilemma and other discrete-time reciprocal cooperation games, which inherently feature a delay in information exchange. Here, we study the evolution of cooperation when individuals can dynamically respond to each other׳s actions.

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openPDS: Protecting the Privacy of Metadata through SafeAnswers

openPDS: Protecting the Privacy of Metadata through SafeAnswers | Papers | Scoop.it

The rise of smartphones and web services made possible the large-scale collection of personal metadata. Information about individuals' location, phone call logs, or web-searches, is collected and used intensively by organizations and big data researchers. Metadata has however yet to realize its full potential. Privacy and legal concerns, as well as the lack of technical solutions for personal metadata management is preventing metadata from being shared and reconciled under the control of the individual. This lack of access and control is furthermore fueling growing concerns, as it prevents individuals from understanding and managing the risks associated with the collection and use of their data. Our contribution is two-fold: (1) we describe openPDS, a personal metadata management framework that allows individuals to collect, store, and give fine-grained access to their metadata to third parties. It has been implemented in two field studies; (2) we introduce and analyze SafeAnswers, a new and practical way of protecting the privacy of metadata at an individual level. SafeAnswers turns a hard anonymization problem into a more tractable security one. It allows services to ask questions whose answers are calculated against the metadata instead of trying to anonymize individuals' metadata. The dimensionality of the data shared with the services is reduced from high-dimensional metadata to low-dimensional answers that are less likely to be re-identifiable and to contain sensitive information. These answers can then be directly shared individually or in aggregate. openPDS and SafeAnswers provide a new way of dynamically protecting personal metadata, thereby supporting the creation of smart data-driven services and data science research.


de Montjoye Y-A, Shmueli E, Wang SS, Pentland AS (2014) openPDS: Protecting the Privacy of Metadata through SafeAnswers. PLoS ONE 9(7): e98790. http://dx.doi.org/10.1371/journal.pone.0098790

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Starvation in pregnant mice marks offspring DNA

Starvation in pregnant mice marks offspring DNA | Papers | Scoop.it

A mother’s diet leaves a lasting impact on the health of her descendants. Mice that are starved during pregnancy give birth to pups that later develop diabetes, and whose offspring are also at risk of the disease. Now a new study provides fresh evidence for the controversial idea that chemical or ‘epigenetic’ alterations to the genome — which influence gene activity, but not the DNA sequence — can transmit the effects of environmental exposures across multiple generations


http://www.nature.com/news/starvation-in-pregnant-mice-marks-offspring-dna-1.15534

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Early Warning Signs in Social-Ecological Networks

Early Warning Signs in Social-Ecological Networks | Papers | Scoop.it

A number of social-ecological systems exhibit complex behavior associated with nonlinearities, bifurcations, and interaction with stochastic drivers. These systems are often prone to abrupt and unexpected instabilities and state shifts that emerge as a discontinuous response to gradual changes in environmental drivers. Predicting such behaviors is crucial to the prevention of or preparation for unwanted regime shifts. Recent research in ecology has investigated early warning signs that anticipate the divergence of univariate ecosystem dynamics from a stable attractor. To date, leading indicators of instability in systems with multiple interacting components have remained poorly investigated. This is a major limitation in the understanding of the dynamics of complex social-ecological networks. Here, we develop a theoretical framework to demonstrate that rising variance—measured, for example, by the maximum element of the covariance matrix of the network—is an effective leading indicator of network instability. We show that its reliability and robustness depend more on the sign of the interactions within the network than the network structure or noise intensity. Mutualistic, scale free and small world networks are less stable than their antagonistic or random counterparts but their instability is more reliably predicted by this leading indicator. These results provide new advances in multidimensional early warning analysis and offer a framework to evaluate the resilience of social-ecological networks.


Early Warning Signs in Social-Ecological Networks.

PLoS ONE 9(7): e101851. doi:10.1371/journal.pone.0101851 (2014)

Suweis Samir, D'Odorico Paolo


Code of the analysis available at https://github.com/suweis


http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0101851

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Complexity at the social science interface

This article introduces a special issue of Complexity dedicated to the increasingly important element of complexity science that engages with social policy. We introduce and frame an emerging research agenda that seeks to enhance social policy by working at the interface between the social sciences and the physical sciences (including mathematics and computer science), and term this research area the “social science interface” by analogy with research at the life sciences interface. We locate and exemplify the contribution of complexity science at this new interface before summarizing the contributions collected in this special issue and identifying some common themes that run through them.


Complexity at the social science interface
Nigel Gilbert and Seth Bullock

Complexity
Volume 19, Issue 6, pages 1–4, July/August 2014

http://dx.doi.org/10.1002/cplx.21550


Special Issue on Complexity Science and Social Policy


http://onlinelibrary.wiley.com/doi/10.1002/cplx.v19.6/issuetoc

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Your Brain Is On the Brink of Chaos

Your Brain Is On the Brink of Chaos | Papers | Scoop.it

In one important way, the recipient of a heart transplant ignores its new organ: Its nervous system usually doesn’t rewire to communicate with it. The 40,000 neurons controlling a heart operate so perfectly, and are so self-contained, that a heart can be cut out of one body, placed into another, and continue to function perfectly, even in the absence of external control, for a decade or more. This seems necessary: The parts of our nervous system managing our most essential functions behave like a Swiss watch, precisely timed and impervious to perturbations. Chaotic behavior has been throttled out.

Or has it? Two simple pendulums that swing with perfect regularity can, when yoked together, move in a chaotic trajectory. Given that the billions of neurons in our brain are each like a pendulum, oscillating back and forth between resting and firing, and connected to 10,000 other neurons, isn’t chaos in our nervous system unavoidable?


http://nautil.us/issue/15/turbulence/your-brain-is-on-the-brink-of-chaos

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Multispecies diel transcriptional oscillations in open ocean heterotrophic bacterial assemblages

Oscillating diurnal rhythms of gene transcription, metabolic activity, and behavior are found in all three domains of life. However, diel cycles in naturally occurring heterotrophic bacteria and archaea have rarely been observed. Here, we report time-resolved whole-genome transcriptome profiles of multiple, naturally occurring oceanic bacterial populations sampled in situ over 3 days. As anticipated, the cyanobacterial transcriptome exhibited pronounced diel periodicity. Unexpectedly, several different heterotrophic bacterioplankton groups also displayed diel cycling in many of their gene transcripts. Furthermore, diel oscillations in different heterotrophic bacterial groups suggested population-specific timing of peak transcript expression in a variety of metabolic gene suites. These staggered multispecies waves of diel gene transcription may influence both the tempo and the mode of matter and energy transformation in the sea.


Multispecies diel transcriptional oscillations in open ocean heterotrophic bacterial assemblages
Elizabeth A. Ottesen, et al.

Science 11 July 2014:
Vol. 345 no. 6193 pp. 207-212
http://dx.doi.org/10.1126/science.1252476

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On the Use of Human Mobility Proxies for Modeling Epidemics

On the Use of Human Mobility Proxies for Modeling Epidemics | Papers | Scoop.it

The spatial dissemination of a directly transmitted infectious disease in a population is driven by population movements from one region to another allowing mixing and importation. Public health policy and planning may thus be more accurate if reliable descriptions of population movements can be considered in the epidemic evaluations. Next to census data, generally available in developed countries, alternative solutions can be found to describe population movements where official data is missing. These include mobility models, such as the radiation model, and the analysis of mobile phone activity records providing individual geo-temporal information. Here we explore to what extent mobility proxies, such as mobile phone data or mobility models, can effectively be used in epidemic models for influenza-like-illnesses and how they compare to official census data. By focusing on three European countries, we find that phone data matches the commuting patterns reported by census well but tends to overestimate the number of commuters, leading to a faster diffusion of simulated epidemics. The order of infection of newly infected locations is however well preserved, whereas the pattern of epidemic invasion is captured with higher accuracy by the radiation model for centrally seeded epidemics and by phone proxy for peripherally seeded epidemics.


Tizzoni M, Bajardi P, Decuyper A, Kon Kam King G, Schneider CM, et al. (2014) On the Use of Human Mobility Proxies for Modeling Epidemics. PLoS Comput Biol 10(7): e1003716. http://dx.doi.org/10.1371/journal.pcbi.1003716

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Group Minds and the Case of Wikipedia

Group-level cognitive states are widely observed in human social systems, but their discussion is often ruled out a priori in quantitative approaches. In this paper, we show how reference to the irreducible mental states and psychological dynamics of a group is necessary to make sense of large scale social phenomena. We introduce the problem of mental boundaries by reference to a classic problem in the evolution of cooperation. We then provide an explicit quantitative example drawn from ongoing work on cooperation and conflict among Wikipedia editors. We show the limitations of methodological individualism, and the substantial benefits that come from being able to refer to collective intentions and attributions of cognitive states of the form "what the group believes" and "what the group values".


Group Minds and the Case of Wikipedia
Simon DeDeo

http://arxiv.org/abs/1407.2210

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Null Models for Community Detection in Spatially-Embedded, Temporal Networks

In the study of networks, it is often insightful to use algorithms to determine mesoscale features such as "community structure", in which densely connected sets of nodes constitute "communities" that have sparse connections to other communities. The most popular way of detecting communities algorithmically is to optimize the quality function known as modularity. When optimizing modularity, one compares the actual connections in a (static or time-dependent) network to the connections obtained from a random-graph ensemble that acts as a null model. The communities are then the sets of nodes that are connected to each other densely relative to what is expected from the null model. Clearly, the process of community detection depends fundamentally on the choice of null model, so it is important to develop and analyze novel null models that take into account appropriate features of the system under study. In this paper, we investigate the effects of using null models that take incorporate spatial information, and we propose a novel null model based on the radiation model of population spread. We also develop novel synthetic spatial benchmark networks in which the connections between entities are based on distance or flux between nodes, and we compare the performance of both static and time-dependent radiation null models to the standard ("Newman-Girvan") null model for modularity optimization and a recently-proposed gravity null model. In our comparisons, we use both the above synthetic benchmarks and time-dependent correlation networks that we construct using countrywide dengue fever incidence data for Peru. We also evaluate a recently-proposed correlation null model, which was developed specifically for correlation networks that are constructed from time series, on the epidemic-correlation data.


Null Models for Community Detection in Spatially-Embedded, Temporal Networks
Marta Sarzynska, Elizabeth A. Leicht, Gerardo Chowell, Mason A. Porter

http://arxiv.org/abs/1407.6297

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Biosemiotic Entropy: Concluding the Series

This article concludes the special issue on Biosemiotic Entropy looking toward the future on the basis of current and prior results. It highlights certain aspects of the series, concerning factors that damage and degenerate biosignaling systems. As in ordinary linguistic discourse, well-formedness (coherence) in biological signaling systems depends on valid representations correctly construed: a series of proofs are presented and generalized to all meaningful sign systems. The proofs show why infants must (as empirical evidence shows they do) proceed through a strict sequence of formal steps in acquiring any language. Classical and contemporary conceptions of entropy and information are deployed showing why factors that interfere with coherence in biological signaling systems are necessary and sufficient causes of disorders, diseases, and mortality. Known sources of such formal degeneracy in living organisms (here termed, biosemiotic entropy) include: (a) toxicants, (b) pathogens; (c) excessive exposures to radiant energy and/or sufficiently powerful electromagnetic fields; (d) traumatic injuries; and (e) interactions between the foregoing factors. Just as Jaynes proved that irreversible changes invariably increase entropy, the theory of true narrative representations (TNR theory) demonstrates that factors disrupting the well-formedness (coherence) of valid representations, all else being held equal, must increase biosemiotic entropy—the kind impacting biosignaling systems.


Biosemiotic Entropy: Concluding the Series
by John W. Oller
Entropy 2014, 16(7), 4060-4087; http://dx.doi.org/10.3390/e16074060

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The future lies in uncertainty


Statisticians have celebrated a lot recently. 2013 marked the 300th anniversary of Jacob Bernoulli's Ars Conjectandi, which used probability theory to explore the properties of statistics as more observations were taken. It was also the 250th anniversary of Thomas Bayes' essay on how humans can sequentially learn from experience, steadily updating their beliefs as more data become available (1). And it was the International Year of Statistics (2). Now that the bunting has been taken down, it is a good time to take stock of recent developments in statistical science and examine its role in the age of Big Data.
Much enthusiasm for statistics hangs on the ever-increasing availability of large data sets, particularly when something has to be ranked or classified. These situations arise, for example, when deciding which book to recommend, working out where your arm is when practicing golf swings in front of a games console, or (if you're a security agency) deciding whose private e-mail to read first. Purely data-based approaches, under the title of machine-learning, have been highly successful in speech recognition, real-time interpretation of moving images, and online translation.


The future lies in uncertainty
. D. J. Spiegelhalter

Science 18 July 2014:
Vol. 345 no. 6194 pp. 264-265
http://dx.doi.org/10.1126/science.1251122

Complexity Digest's insight:

“Predicting the past is very easy. Predicting the future is not so easy” -Ignacio Méndez

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How collective comparisons emerge without individual comparisons of the options

Collective decisions in animal groups emerge from the actions of individuals who are unlikely to have global information. Comparative assessment of options can be valuable in decision-making. Ant colonies are excellent collective decision-makers, for example when selecting a new nest-site.

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Cluster Statistics and Universal Aspects of the Optimal Velocity Model in the Non-Linear Regime

We show that in the non-linear regime of the optimal velocity model, there is an emergent quantity that gives the extremum headways in the cluster formation, as well as the coexistence curve separating the absolute stable phase from the metastable phase. This emergent quantity is independent of the density of the traffic lane, and determines the width of the transition region from the minimum headways (or clusters) to the maximum headways (or anti-clusters). The width also gives an intrinsic scale that controls the strength of interaction between multiple clusters. This leads to non-trivial cluster statistics from random initial perturbations, and the statistics also depends on the density of the traffic lane. We conjecture these aspects are universal features for various different car-following models.

 

 

Cluster Statistics and Universal Aspects of the Optimal Velocity Model in the Non-Linear Regime
B Yang, X Xu, Z.F. Pang, C Monterola

http://arxiv.org/abs/1407.3177

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“What Is the Teacher Trying to Teach Students if They Are All Busy Constructing Their Own Private Worlds?”: Introduction to the Special Issue

“What Is the Teacher Trying to Teach Students if They Are All Busy Constructing Their Own Private Worlds?”: Introduction to the Special Issue | Papers | Scoop.it

Context: Ernst von Glasersfeld introduced radical constructivism in 1974 as a new interpretation of Jean Piaget’s constructivism to give new meanings to the notions of knowledge, communication, and reality. He also claimed that RC would affect traditional theories of education. Problem: After 40 years it has become necessary to review and evaluate von Glasersfeld’s claim. Also, has RC been successful in taking the “social turn” in educational research, or is it unable to go beyond “private worlds? Method: We provide an overview of contributed articles that were written with the aim of showing whether RC has an impact on educational research, and we discuss three core issues: Can RC account for inter-individual aspects? Is RC a theory of learning? And should Piaget be regarded as a radical constructivist? Results: We argue that the contributed papers demonstrate the efficiency of the application of RC to educational research and practice. Our argumentation also shows that in RC it would be misleading to claim a dichotomy between cognition and social interaction (rather, social constructivism is a radical constructivism), that RC does not contain a theory of mathematics learning any more or less than it contains a theory of mathematics teaching, and that Piaget should not be considered a mere trivial constructivist. Implications: Still one of the most challenging influences on educational research and practice, RC is ready to embark on many further questions, including its relationship with other constructivist paradigms, and to make progress in the social dimension.


Riegler A. & Steffe L. P. (2014) “What Is the Teacher Trying to Teach Students if They Are All Busy Constructing Their Own Private Worlds?”: Introduction to the Special Issue. Constructivist Foundations 9(3): 297–301. Available at http://www.univie.ac.at/constructivism/journal/9/3/297.editorial

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Perceiving invisible light through a somatosensory cortical prosthesis

Sensory neuroprostheses show great potential for alleviating major sensory deficits. It is not known, however, whether such devices can augment the subject’s normal perceptual range. Here we show that adult rats can learn to perceive otherwise invisible infrared light through a neuroprosthesis that couples the output of a head-mounted infrared sensor to their somatosensory cortex (S1) via intracortical microstimulation. Rats readily learn to use this new information source, and generate active exploratory strategies to discriminate among infrared signals in their environment. S1 neurons in these infrared-perceiving rats respond to both whisker deflection and intracortical microstimulation, suggesting that the infrared representation does not displace the original tactile representation. Hence, sensory cortical prostheses, in addition to restoring normal neurological functions, may serve to expand natural perceptual capabilities in mammals.


Perceiving invisible light through a somatosensory cortical prosthesis
• Eric E. Thomson, Rafael Carra & Miguel A.L. Nicolelis

Nature Communications 4, Article number: 1482 http://dx.doi.org/10.1038/ncomms2497

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Spatial maximum entropy modeling from presence/absence tropical forest data

Understanding the assembly of ecosystems to estimate the number of species at different spatial scales is a challenging problem. Until now, maximum entropy approaches have lacked the important feature of considering space in an explicit manner. We propose a spatially explicit maximum entropy model suitable to describe spatial patterns such as the species area relationship and the endemic area relationship. Starting from the minimal information extracted from presence/absence data, we compare the behavior of two models considering the occurrence or lack thereof of each species and information on spatial correlations. Our approach uses the information at shorter spatial scales to infer the spatial organization at larger ones. We also hypothesize a possible ecological interpretation of the effective interaction we use to characterize spatial clustering. (http://arxiv.org/abs/1407.2425)

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Cooperating with the future

Overexploitation of renewable resources today has a high cost on the welfare of future generations. Unlike in other public goods games, however, future generations cannot reciprocate actions made today. What mechanisms can maintain cooperation with the future? To answer this question, we devise a new experimental paradigm, the /`Intergenerational Goods Game/'. A line-up of successive groups (generations) can each either extract a resource to exhaustion or leave something for the next group. Exhausting the resource maximizes the payoff for the present generation, but leaves all future generations empty-handed. Here we show that the resource is almost always destroyed if extraction decisions are made individually. This failure to cooperate with the future is driven primarily by a minority of individuals who extract far more than what is sustainable. In contrast, when extractions are democratically decided by vote, the resource is consistently sustained. Voting is effective for two reasons. First, it allows a majority of cooperators to restrain defectors. Second, it reassures conditional cooperators that their efforts are not futile. Voting, however, only promotes sustainability if it is binding for all involved. Our results have implications for policy interventions designed to sustain intergenerational public goods.


Cooperating with the future
Oliver P. Hauser, David G. Rand, Alexander Peysakhovich & Martin A. Nowak

Nature 511, 220–223 (10 July 2014) http://dx.doi.org/10.1038/nature13530

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Connecting Core Percolation and Controllability of Complex Networks

Connecting Core Percolation and Controllability of Complex Networks | Papers | 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.


Connecting Core Percolation and Controllability of Complex Networks
• Tao Jia & Márton Pósfai

Scientific Reports 4, Article number: 5379 http://dx.doi.org/10.1038/srep05379


Via Shaolin Tan
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Fascinating advances

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Coding Together at Scale: GitHub as a Collaborative Social Network

GitHub is the most popular repository for open source code. It has more than 3.5 million users, as the company declared in April 2013, and more than 10 million repositories, as of December 2013. It has a publicly accessible API and, since March 2012, it also publishes a stream of all the events occurring on public projects. Interactions among GitHub users are of a complex nature and take place in different forms. Developers create and fork repositories, push code, approve code pushed by others, bookmark their favorite projects and follow other developers to keep track of their activities.
In this paper we present a characterization of GitHub, as both a social network and a collaborative platform. To the best of our knowledge, this is the first quantitative study about the interactions happening on GitHub. We analyze the logs from the service over 18 months (between March 11, 2012 and September 11, 2013), describing 183.54 million events and we obtain information about 2.19 million users and 5.68 million repositories, both growing linearly in time. We show that the distributions of the number of contributors per project, watchers per project and followers per user show a power-law-like shape. We analyze social ties and repository-mediated collaboration patterns, and we observe a remarkably low level of reciprocity of the social connections. We also measure the activity of each user in terms of authored events and we observe that very active users do not necessarily have a large number of followers. Finally, we provide a geographic characterization of the centers of activity and we investigate how distance influences collaboration.


Coding Together at Scale: GitHub as a Collaborative Social Network
Antonio Lima, Luca Rossi, Mirco Musolesi

http://arxiv.org/abs/1407.2535

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Change in the Embedding Dimension as an Indicator of an Approaching Transition

Predicting a transition point in behavioral data should take into account the complexity of the signal being influenced by contextual factors. In this paper, we propose to analyze changes in the embedding dimension as contextual information indicating a proceeding transitive point, called OPtimal Embedding tRANsition Detection (OPERAND). Three texts were processed and translated to time-series of emotional polarity. It was found that changes in the embedding dimension proceeded transition points in the data. These preliminary results encourage further research into changes in the embedding dimension as generic markers of an approaching transition point.


Neuman Y, Marwan N, Cohen Y (2014) Change in the Embedding Dimension as an Indicator of an Approaching Transition. PLoS ONE 9(6): e101014. http://dx.doi.org/10.1371/journal.pone.0101014

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