martes, 27 de agosto de 2013

Learn about the latest and greatest related to complex systems research.




Complexity Digest

Contents:

Sentiment in New York City: A High Resolution Spatial and Temporal View


Measuring public sentiment is a key task for researchers and policymakers alike. The explosion of available social media data allows for a more time-sensitive and geographically specific analysis than ever before. In this paper we analyze data from the micro-blogging site Twitter and generate a sentiment map of New York City. We develop a classifier specifically tuned for 140-character Twitter messages, or tweets, using key words, phrases and emoticons to determine the mood of each tweet. This method, combined with geotagging provided by users, enables us to gauge public sentiment on extremely fine-grained spatial and temporal scales. We find that public mood is generally highest in public parks and lowest at transportation hubs, and locate other areas of extreme sentiment such as cemeteries, medical centers, a jail, and a sewage facility. Sentiment progressively improves with proximity to Times Square. Periodic patterns of sentiment fluctuate on both a daily and a weekly scale: more positive tweets are posted on weekends than on weekdays, with a daily peak in sentiment around midnight and a nadir between 9:00 a.m. and noon.
 
K.Z. Bertrand, M. Bialik, K. Virdee, A. Gros, Y. Bar-Yam, Sentiment in New York City: A High Resolution Spatial and Temporal View. NECSI Report 2013-08-01 (08/20/2013).
http://necsi.edu/research/social/newyork/


 share on Twitter Like Sentiment in New York City: A High Resolution Spatial and Temporal View on Facebook

Understanding metropolitan patterns of daily encounters

Understanding of the mechanisms driving our daily face-to-face encounters is still limited; the field lacks large-scale datasets describing both individual behaviors and their collective interactions. However, here, with the help of travel smart card data, we uncover such encounter mechanisms and structures by constructing a time-resolved in-vehicle social encounter network on public buses in a city (about 5 million residents). Using a population scale dataset, we find physical encounters display reproducible temporal patterns, indicating that repeated encounters are regular and identical. On an individual scale, we find that collective regularities dominate distinct encounters’ bounded nature. An individual’s encounter capability is rooted in his/her daily behavioral regularity, explaining the emergence of “familiar strangers” in daily life. Strikingly, we find individuals with repeated encounters are not grouped into small communities, but become strongly connected over time, resulting in a large, but imperceptible, small-world contact network or “structure of co-presence” across the whole metropolitan area. Revealing the encounter pattern and identifying this large-scale contact network are crucial to understanding the dynamics in patterns of social acquaintances, collective human behaviors, and—particularly—disclosing the impact of human behavior on various diffusion/spreading processes.
 
Understanding metropolitan patterns of daily encounters
Lijun Sun, Kay W. Axhausen, Der-Horng Lee, and Xianfeng Huang
http://dx.doi.org/10.1073/pnas.1306440110
PNAS August 20, 2013 vol. 110 no. 34 13774-13779


 share on Twitter Like Understanding metropolitan patterns of daily encounters on Facebook

Emergence of structural and dynamical properties of ecological mutualistic networks

Cooperation among species tends to result in mutualistic networks with a nested structure, which is thought to increase biodiversity and persistence but may be less stable than unstructured networks: here nested networks are shown to result from a mechanism that maximizes species abundances in mutualistic communities, and the abundance of nested species is found to be directly linked to the resilience of the community.
 
Emergence of structural and dynamical properties of ecological mutualistic networks
Samir Suweis, Filippo Simini, Jayanth R. Banavar & Amos Maritan
Nature 500, 449–452 (22 August 2013) http://dx.doi.org/10.1038/nature12438


 share on Twitter Like Emergence of structural and dynamical properties of ecological mutualistic networks on Facebook

The Health Risk of Obesity—Better Metrics Imperative

Obesity has increased worldwide; is a major risk factor for diabetes, cardiovascular disease, cancer, sleep apnea, nonalcoholic fatty liver disease, osteoarthritis, and other ailments; and has been associated with disability, mortality, and enormous health costs (1, 2). Despite these clear adverse consequences of obesity, some studies have suggested that obesity as defined by body mass index (BMI) improves survival under certain conditions (3–8). Here, we discuss the controversies surrounding the “obesity-mortality paradox” and offer potential mechanisms to explain the effects of obesity on health.
 
The Health Risk of Obesity—Better Metrics Imperative
Rexford S. Ahima, Mitchell A. Lazar
Science 23 August 2013:
Vol. 341 no. 6148 pp. 856-858
http://dx.doi.org/10.1126/science.1241244

Complexity Digest's insight:
The relationship between obesity and disease is clearly nonlinear: there are healthy overweight people and also ill people with a normal weight.

 share on Twitter Like The Health Risk of Obesity—Better Metrics Imperative on Facebook

Mom Knows Best: The Universality of Maternal Microbial Transmission


The sterile womb paradigm is an enduring premise in biology that human infants are born sterile. Recent studies suggest that infants incorporate an initial microbiome before birth and receive copious supplementation of maternal microbes through birth and breastfeeding. Moreover, evidence for microbial maternal transmission is increasingly widespread across animals. This collective knowledge compels a paradigm shift—one in which maternal transmission of microbes advances from a taxonomically specialized phenomenon to a universal one in animals. It also engenders fresh views on the assembly of the microbiome, its role in animal evolution, and applications to human health and disease.
 
Funkhouser LJ, Bordenstein SR (2013) Mom Knows Best: The Universality of Maternal Microbial Transmission. PLoS Biol 11(8): e1001631.http://dx.doi.org/10.1371/journal.pbio.1001631


 share on Twitter Like Mom Knows Best: The Universality of Maternal Microbial Transmission on Facebook

A place-focused model for social networks in cities

The focused organization theory of social ties proposes that the structure of human social networks can be arranged around extra-network foci, which can include shared physical spaces such as homes, workplaces, restaurants, and so on. Until now, this has been difficult to investigate on a large scale, but the huge volume of data available from online location-based social services now makes it possible to examine the friendships and mobility of many thousands of people, and to investigate the relationship between meetings at places and the structure of the social network. In this paper, we analyze a large dataset from Foursquare, the most popular online location-based social network. We examine the properties of city-based social networks, finding that they have common structural properties, and that the category of place where two people meet has very strong influence on the likelihood of their being friends. Inspired by these observations in combination with the focused organization theory, we then present a model to generate city-level social networks, and show that it produces networks with the structural properties seen in empirical data.
 
A place-focused model for social networks in cities
Chloë Brown, Anastasios Noulas, Cecilia Mascolo, Vincent Blondel
http://arxiv.org/abs/1308.2565


 share on Twitter Like A place-focused model for social networks in cities on Facebook

International Co-authorship Relations in the Social Science Citation Index: Is Internationalization Leading the Network?

We analyze international co-authorship relations in the Social Science Citation Index 2011 using all citable items in the DVD-version of this index. Network statistics indicate four groups of nations: (i) an Asian-Pacific one to which all Anglo-Saxon nations (including the UK and Ireland) are attributed; (ii) a continental European one including also the Latin-American countries; (iii) the Scandinavian nations; and (iv) a community of African nations. Within the EU-28 (including Croatia), eleven of the EU-15 states have dominant positions. Collapsing the EU-28 into a single node leads to a bi-polar structure between the US and EU-28; China is part of the US-pole. We develop an information-theoretical test to distinguish whether international collaborations or domestic collaborations prevail; the results are mixed, but the international dimension is more important than the national one in the aggregated sets (this was found in both SSCI and SCI). In France, however, the national distribution is more important than the international one, while the reverse is true for most European nations in the core group (UK, Germany, the Netherlands, etc.). Decomposition of the USA in terms of states shows a similarly mixed result; more US states are domestically oriented in SSCI, whereas more internationally in SCI. The international networks have grown during the last decades in addition to the national ones, but not by replacing them.
 
International Co-authorship Relations in the Social Science Citation Index: Is Internationalization Leading the Network?
Loet Leydesdorff, Han Woo Park, Caroline Wagner
http://arxiv.org/abs/1305.4242


 share on Twitter Like International Co-authorship Relations in the Social Science Citation Index: Is Internationalization Leading the Network? on Facebook

The Limits of Phenomenology: From Behaviorism to Drug Testing and Engineering Design

It is widely believed that theory is useful in physics because it describes simple systems and that strictly empirical phenomenological approaches are necessary for complex biological and social systems. Here we prove based upon an analysis of the information that can be obtained from experimental observations that theory is even more essential in the understanding of complex systems. Implications of this proof revise the general understanding of how we can understand complex systems including the behaviorist approach to human behavior, problems with testing engineered systems, and medical experimentation for evaluating treatments and the FDA approval of medications. Each of these approaches are inherently limited in their ability to characterize real world systems due to the large number of conditions that can affect their behavior. Models are necessary as they can help to characterize behavior without requiring observations for all possible conditions. The testing of models by empirical observations enhances the utility of those observations. For systems for which adequate models have not been developed, or are not practical, the limitations of empirical testing lead to uncertainty in our knowledge and risks in individual, organizational and social policy decisions. These risks should be recognized and inform our decisions.
 
The Limits of Phenomenology: From Behaviorism to Drug Testing and Engineering Design
Yaneer Bar-Yam
http://arxiv.org/abs/1308.3094


 share on Twitter Like The Limits of Phenomenology: From Behaviorism to Drug Testing and Engineering Design on Facebook

Estimating the tolerance of species to the effects of global environmental change

Global environmental change is affecting species distribution and their interactions with other species. In particular, the main drivers of environmental change strongly affect the strength of interspecific interactions with considerable consequences to biodiversity. However, extrapolating the effects observed on pair-wise interactions to entire ecological networks is challenging. Here we propose a framework to estimate the tolerance to changes in the strength of mutualistic interaction that species in mutualistic networks can sustain before becoming extinct. We identify the scenarios where generalist species can be the least tolerant. We show that the least tolerant species across different scenarios do not appear to have uniquely common characteristics. Species tolerance is extremely sensitive to the direction of change in the strength of mutualistic interaction, as well as to the observed mutualistic trade-offs between the number of partners and the strength of the interactions.
 
Estimating the tolerance of species to the effects of global environmental change
Serguei Saavedra, Rudolf P. Rohr, Vasilis Dakos, Jordi Bascompte
http://arxiv.org/abs/1308.3584


 share on Twitter Like Estimating the tolerance of species to the effects of global environmental change on Facebook

Do the rich get richer? An empirical analysis of the BitCoin transaction network

The possibility to analyze everyday monetary transactions is limited by the scarcity of available data, as this kind of information is usually considered highly sensitive. Present econophysics models are usually employed on presumed random networks of interacting agents, and only macroscopic properties (e.g. the resulting wealth distribution) are compared to real-world data. In this paper, we analyze BitCoin, which is a novel digital currency system, where the complete list of transactions is publicly available. Using this dataset, we reconstruct the network of transactions, and extract the time and amount of each payment. We analyze the structure of the transaction network by measuring network characteristics over time, such as the degree distribution, degree correlations and clustering. We find that linear preferential attachment drives the growth of the network. We also study the dynamics taking place on the transaction network, i.e. the flow of money. We measure temporal patterns and the wealth accumulation. Investigating the microscopic statistics of money movement, we find that sublinear preferential attachment governs the evolution of the wealth distribution. We report a scaling relation between the degree and wealth associated to individual nodes.
 
Do the rich get richer? An empirical analysis of the BitCoin transaction network
Dániel Kondor, Máton Pósfai, István Csabai, Gábor Vattay
http://arxiv.org/abs/1308.3892


 share on Twitter Like Do the rich get richer? An empirical analysis of the BitCoin transaction network on Facebook

Artificial Economics and Self Organization: Agent-Based Approaches to Economics and Social Systems (edited by Stephan Leitner and Friederike Wall)

This volume presents recent advances in the dynamic field of Artificial Economics and its various applications. Artificial Economics provides a structured approach to model and investigate economic and social systems. In particular, this approach is based on the use of agent-based simulations and further computational techniques. The main aim is to analyze the outcomes at the overall systems’ level as results from the agents’ behavior at the micro-level. These emergent characteristics of complex economic and social systems can neither be foreseen nor are they intended. The emergence rather makes these systems function. Artificial Economics especially facilitates the investigation of this emergent systems’ behavior.
 
 


 share on Twitter Like Artificial Economics and Self Organization: Agent-Based Approaches to Economics and Social Systems (edited by Stephan Leitner and Friederike Wall) on Facebook

Proceedings of the European Conference on Complex Systems 2012 (by Thomas Gilbert, Markus Kirkilionis, Gregoire Nicolis)

The European Conference on Complex Systems, held under the patronage of the Complex Systems Society, is an annual event that has become the leading European conference devoted to complexity science. ECCS'12, its ninth edition, took place in Brussels, during the first week of September 2012. It gathered about 650 scholars representing a wide range of topics relating to complex systems research, with emphasis on interdisciplinary approaches. More specifically, the following tracks were covered:
 
1. Foundations of Complex Systems;
2. Complexity, Information and Computation;
3. Prediction, Policy and Planning, Environment;
4. Biological Complexity;
5. Interacting Populations, Collective Behavior;
6. Social Systems, Economics and Finance.
 
This book contains a selection of the contributions presented at the conference and its satellite meetings. Its contents reflect the extent, diversity and richness of research areas in the field, both fundamental and applied.
 
 


 share on Twitter Like Proceedings of the European Conference on Complex Systems 2012 (by Thomas Gilbert, Markus Kirkilionis, Gregoire Nicolis) on Facebook

Advances in Network Complexity (by Matthias Dehmer, Abbe Mowshowitz, Frank Emmert-Streib)

A well-balanced overview of mathematical approaches to describe complex systems, ranging from chemical reactions to gene regulation networks, from ecological systems to examples from social sciences. Matthias Dehmer and Abbe Mowshowitz, a well-known pioneer in the field, co-edit this volume and are careful to include not only classical but also non-classical approaches so as to ensure topicality.
Overall, a valuable addition to the literature and a must-have for anyone dealing with complex systems.
 
 


 share on Twitter Like Advances in Network Complexity (by Matthias Dehmer, Abbe Mowshowitz, Frank Emmert-Streib) on Facebook

Worms Can Pass a Trait Down for 100 Generations…Without Using DNA


A new paper in Cell reports that worms whose grandparents had the ability to fight viruses using a fleet of tiny RNA molecules retain these molecules even when they don’t have the genes for them. They can pass these molecules down for more than a hundred generations.


 share on Twitter Like Worms Can Pass a Trait Down for 100 Generations…Without Using DNA on Facebook

Tomorrow's Cities


Have you ever wondered where you or your children may be living in 2050? Experts predict that by then three-quarters of the world's population will live in cities. This August and September the BBC is taking a look at how our lives will be changed by the technological innovations being developed for Tomorrow’s Cities.
 
http://www.bbc.co.uk/news/technology-23517670


 share on Twitter Like Tomorrow's Cities on Facebook

Russell Foster: Why do we sleep?


Russell Foster is a circadian neuroscientist: He studies the sleep cycles of the brain. And he asks: What do we know about sleep? Not a lot, it turns out, for something we do with one-third of our lives. In this talk, Foster shares three popular theories about why we sleep, busts some myths about how much sleep we need at different ages -- and hints at some bold new uses of sleep as a predictor of mental health.
 
http://www.ted.com/talks/russell_foster_why_do_we_sleep.html


 share on Twitter Like Russell Foster: Why do we sleep? on Facebook

Guiding Designs of Self-Organizing Swarms: Interactive and Automated Approaches

Self-organization of heterogeneous particle swarms is rich in its dynamics but hard to design in a traditional top-down manner, especially when many types of kinetically distinct particles are involved. In this chapter, we discuss how we have been addressing this problem by (1) utilizing and enhancing interactive evolutionary design methods and (2) realizing spontaneous evolution of self organizing swarms within an artificial ecosystem.
 
Guiding Designs of Self-Organizing Swarms: Interactive and Automated Approaches
Hiroki Sayama
http://arxiv.org/abs/1308.3400


 share on Twitter Like Guiding Designs of Self-Organizing Swarms: Interactive and Automated Approaches on Facebook

Agent-based modeling and simulation of emergent behavior in air transportation

Commercial aviation is feasible thanks to the complex socio-technical air transportation system, which involves interactions between human operators, technical systems, and procedures. In view of the expected growth in commercial aviation, significant changes in this socio-technical system are in development both in the USA and Europe. Such a complex socio-technical system may generate various types of emergent behavior, which may range from simple emergence, through weak emergence, up to strong emergence. The purpose of this paper is to demonstrate that agent-based modeling and simulation allows identifying changed and novel rare emergent behavior in this complex socio-technical system. (...)
 
Agent-based modeling and simulation of emergent behavior in air transportation
Bouarfa S, Blom HA, Curran R, Everdij MH
Complex Adaptive Systems Modeling 2013, 1:15 (15 August 2013)
http://dx.doi.org/10.1186/2194-3206-1-15


 share on Twitter Like Agent-based modeling and simulation of emergent behavior in air transportation on Facebook

Information and Life (by Gérard Battail)

Communication, one of the most important functions of life, occurs at any spatial scale from the molecular one up to that of populations and ecosystems, and any time scale from that of fast chemical reactions up to that of geological ages. Information theory, a mathematical science of communication initiated by Shannon in 1948, has been very successful in engineering, but biologists ignore it.
 
This book aims at bridging this gap. It proposes an abstract definition of information based on the engineers' experience which makes it usable in life sciences. It expounds information theory and error-correcting codes, its by-products, as simply as possible. Then, the fundamental biological problem of heredity is examined. It is shown that biology does not adequately account for the conservation of genomes during geological ages, which can be understood only if it is assumed that genomes are made resilient to casual errors by proper coding. Moreover, the good conservation of very old parts of genomes, like the HOX genes, implies that the assumed genomic codes have a nested structure which makes an information the more resilient to errors, the older it is.
 
The consequences that information theory draws from these hypotheses meet very basic but yet unexplained biological facts, e.g., the existence of successive generations, that of discrete species and the trend of evolution towards complexity. Being necessarily inscribed on physical media, information appears as a bridge between the abstract and the concrete. Recording, communicating and using information exclusively occur in the living world. Information is thus coextensive with life and delineates the border between the living and the inanimate.
 
 


 share on Twitter Like Information and Life (by Gérard Battail) on Facebook

More to read:

Time Reborn: a new theory of time - a new view of the world
Counterfactuals and Causal Models: Introduction to the Special Issue
Limited Urban Growth: London's Street Network Dynamics since the 18th Century
Controlling Self-Organizing Dynamics on Networks Using Models that Self-Organize
A Network Extension of Species Occupancy Models in a Patchy Environment Applied to the Yosemite Toad (Anaxyrus canorus)
Complexity Theory and the Social Sciences: The state of the art (by David Byrne, Gillian Callaghan)
The Why of Things: Causality in Science, Medicine, and Life (by Peter V. Rabins)
The Outer Limits of Reason: What Science, Mathematics, and Logic Cannot Tell Us (by Noson S. Yanofsky)
Animal Body Size: Linking Pattern and Process across Space, Time, and Taxonomic Group (by Felisa A. Smith, S. Kathleen Lyons)
Handbook of Human Computation: Pietro Michelucci
Founding Editor: Gottfried Mayer.
Editor-in-Chief: Carlos Gershenson.
To manage subscriptions, please go tohttp://comdig.unam.mx/subscriptions.php
You can contribute to Complexity Digest selecting one of our topics and using the "Suggest" button.

Source: 

[comdig] Latest Complexity Digest Posts

1 comentario:

rupali thakur dijo...

Atentos al Atrapa Al Gato siguiente vídeo donde podemos ver a un supuesto falso interprete de sordos durante el discurso del funeral de Nelson Mandela.