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   Barry Wellman
  _______________________________________________________________________
   FRSC                 INSNA Founder               University of Toronto
   http://www.chass.utoronto.ca/~wellman           twitter: @barrywellman
   NETWORKED:The New Social Operating System.  Lee Rainie & Barry Wellman
   MIT Press            http://amzn.to/zXZg39        Print $14  Kindle $9
   _______________________________________________________________________


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Date: Mon, 22 Jun 2015 11:03:33 +0000
From: "[utf-8] Complexity Digest" <[log in to unmask]>
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To: "[utf-8] Barry" <[log in to unmask]>
Subject: [utf-8] Latest Complexity Digest Posts


Shared decision-making drives collective movement in wild baboons

    How do groups of animals, including humans, make decisions that affect the entire group? Evidence collected from schooling animals suggests that the process is somewhat democratic, with nearest neighbors and the majority shaping overall collective behavior. In animals with hierarchical social structures such as primates or wolves, however, such democracy may be complicated by dominance. Strandburg-Peshkin et al. monitored all the individuals within a baboon troop continuously over the course of their daily activities. Even within this highly socially structured species, movement decisions emerged via a shared process. Thus, democracy may be an inherent trait of collective behavior.

Shared decision-making drives collective movement in wild baboons
Ariana Strandburg-Peshkin, Damien R. Farine, Iain D. Couzin, Margaret C. Crofoot

Science 19 June 2015:
Vol. 348 no. 6241 pp. 1358-1361
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Nature Physics Focus on Complex networks in finance

    The 2008 financial crisis has highlighted major limitations in the modelling of financial and economic systems. However, an emerging field of research at the frontiers of both physics and economics aims to provide a more fundamental understanding of economic networks, as well as practical insights for policymakers. In this Nature Physics Focus, physicists and economists consider the state-of-the-art in the application of network science to finance.

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Exploring dynamic mechanisms of learning networks for resource conservation

    The importance of networks for social-ecological processes has been recognized in the literature; however, existing studies have not sufficiently addressed the dynamic nature of networks. Using data on the social learning networks of 265 farmers in Ethiopia for 2011 and 2012 and stochastic actor-oriented modeling, we explain the mechanisms of network evolution and soil conservation. The farmersˇˇ preferences for information exchange within the same social groups support the creation of interactive, clustered, nonhierarchical structures within the evolving learning networks, which contributed to the diffusion of the practice of composting. The introduced methods can be applied to determine whether and how social networks can be used to facilitate environmental interventions in various contexts.

Matous, P., and Y. Todo. 2015. Exploring dynamic mechanisms of learning networks for resource conservation. Ecology and Society 20(2): 36. http://unam.us4.list-manage2.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=04a2855ed0&e=55e25a0e3e

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The anatomy of urban social networks and its implications in the searchability problem

    The appearance of large geolocated communication datasets has recently increased our understanding of how social networks relate to their physical space. However, many recurrently reported properties, such as the spatial clustering of network communities, have not yet been systematically tested at different scales. In this work we analyze the social network structure of over 25ˇˇmillion phone users from three countries at three different scales: country, provinces and cities. We consistently find that this last urban scenario presents significant differences to common knowledge about social networks. First, the emergence of a giant component in the network seems to be controlled by whether or not the network spans over the entire urban border, almost independently of the population or geographic extension of the city. Second, urban communities are much less geographically clustered than expected. These two findings shed new light on the widely-studied searchability in
self-organized networks. By exhaustive simulation of decentralized search strategies we conclude that urban networks are searchable not through geographical proximity as their country-wide counterparts, but through an homophily-driven community structure.

The anatomy of urban social networks and its implications in the searchability problem
ˇˇ C. Herrera-YagŁe, C. M. Schneider, T. Couronnť, Z. Smoreda, R. M. Benito, P. J. Zufiria & M. C. GonzŠlez

Scientific Reports 5, Article number: 10265 http://unam.us4.list-manage1.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=33824dc874&e=55e25a0e3e

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Contact patterns in a high school: a comparison between data collected using wearable sensors, contact diaries and friendship surveys

    Given their importance in shaping social networks and determining how information or diseases propagate in a population, human interactions are the subject of many data collection efforts. To this aim, different methods are commonly used, from diaries and surveys to wearable sensors. These methods show advantages and limitations but are rarely compared in a given setting. As surveys targeting friendship relations might suffer less from memory biases than contact diaries, it is also interesting to explore how daily contact patterns compare with friendship relations and with online social links. Here we make progresses in these directions by leveraging data from a French high school: face-to-face contacts measured by two concurrent methods, sensors and diaries; self-reported friendship surveys; Facebook links. We compare the data sets and find that most short contacts are not reported in diaries while long contacts have larger reporting probability, with a general tendency to
overestimate durations. Measured contacts corresponding to reported friendship can have durations of any length but all long contacts correspond to reported friendships. Online links not associated to reported friendships correspond to short face-to-face contacts, highlighting the different nature of reported friendships and online links. Diaries and surveys suffer from a low sampling rate, showing the higher acceptability of sensor-based platform. Despite the biases, we found that the overall structure of the contact network, i.e., the mixing patterns between classes, is correctly captured by both self-reported contacts and friendships networks. Overall, diaries and surveys tend to yield a correct picture of the structural organization of the contact network, albeit with much less links, and give access to a sort of backbone of the contact network corresponding to the strongest links in terms of cumulative durations.

Contact patterns in a high school: a comparison between data collected using wearable sensors, contact diaries and friendship surveys
Rossana Mastrandrea, Julie Fournet, Alain Barrat

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Scientists create computational algorithm for fact-checking

    Network scientists at Indiana University have developed a new computational method that can leverage any body of knowledge to aid in the complex human task of fact-checking.

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Analysis of Mťxicoˇˇs Narco-War Network (2007ˇˇ2011)

    Since December 2006, more than a thousand cities in Mťxico have suffered the effects of the war between several drug cartels, amongst themselves, as well as with Mexican armed forces. Sources are not in agreement about the number of casualties of this war, with reports varying from 30 to 100 thousand dead; the economic and social ravages are impossible to quantify. In this work we analyze the official report of casualties in terms of the location and the date of occurrence of the homicides. We show how the violence, as reflected by the number of casualties, has increased over time and spread across the country. Next, based on the correlations between cities in the changes of the monthly number of casualties attributed to organized crime, we construct a narco-war network where nodes are the affected cities and links represent correlations between them. We find that close geographical distance between violent cities does not imply a strong correlation amongst them. We observe
that the dynamics of the conflict has evolved in short-term periods where a small core of violent cities determines the main theatre of the war at each stage. This kind of analysis may also help to describe the emergence and propagation of gang-related violence waves.

Espinal-EnrŪquez J, Larralde H (2015) Analysis of Mťxicoˇˇs Narco-War Network (2007ˇˇ2011). PLoS ONE 10(5): e0126503. http://unam.us4.list-manage1.com/track/click?u=0eb0ac9b4e8565f2967a8304b&id=6f56013a82&e=55e25a0e3e ;

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The evolutionary advantage of cooperation

    The present study asks how cooperation and consequently structure can emerge in many different evolutionary contexts. Cooperation, here, is a persistent behavioural pattern of individual entities pooling and sharing resources. Examples are: individual cells forming multicellular systems whose various parts pool and share nutrients; pack animals pooling and sharing prey; families firms, or modern nation states pooling and sharing financial resources. In these examples, each atomistic decision, at a point in time, of the better-off entity to cooperate poses a puzzle: the better-off entity will book an immediate net loss -- why should it cooperate? For each example, specific explanations have been put forward. Here we point out a very general mechanism -- a sufficient null model -- whereby cooperation can evolve. The mechanism is based the following insight: natural growth processes tend to be multiplicative. In multiplicative growth, ergodicity is broken in such a way that
fluctuations have a net-negative effect on the time-average growth rate, although they have no effect on the growth rate of the ensemble average. Pooling and sharing resources reduces fluctuations, which leaves ensemble averages unchanged but -- contrary to common perception -- increases the time-average growth rate for each cooperator.

The evolutionary advantage of cooperation
Ole Peters, Alexander Adamou

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Noise Matters: The Evolution of Communication (by R. Haven Wiley)

    Noise, as we usually think of it, is background sound that interferes with our ability to hear more interesting sounds. In general terms, though, it is anything that interferes with the reception of signals of any sort. It includes extraneous energy in the environment, degradation of signals in transit, and spontaneous random activity in receivers and signalers. Whatever the cause, the consequence of noise is error by receivers, and these errors are the key to understanding how noise shapes the evolution of communication.


Noise Matters breaks new ground in the scientific understanding of how communication evolves in the presence of noise. Combining insights of signal detection theory with evidence from decades of his own original research, Haven Wiley explains the profound effects of noise on the evolution of communication. The coevolution of signalers and receivers does not result in ideal, noise-free communication, Wiley finds. Instead, signalers and receivers evolve to a joint equilibrium in which communication is effective but never error-free. Noise is inescapable in the evolution of communication.


Wileyˇˇs comprehensive approach considers communication on many different levels of biological organization, from cells to individual organisms, including humans. Social interactions, such as honesty, mate choice, and cooperation, are reassessed in the light of noisy communication. The final sections demonstrate that noise even affects how we think about human language, science, subjectivity, and freedom. Noise Matters thus contributes to understanding the behavior of animals, including ourselves.



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