[comdig] Latest Complexity Digest Posts
Quantum physics: The quantum atom
July 1913 saw Danish physicist Niels Bohr publish the first of three papers setting out a radical new view of the nuclear atom. His idea — a positively charged nucleus ringed by electrons in orbits of discrete energies — explained the frequencies of light emitted by hydrogen as electrons made leaps between orbits. Quantum rules determined the electrons' energies, preventing the instabilities that had plagued previous mechanical models of atoms.
This special issue of Nature explores the origin and legacy of Bohr's quantum atom, a model that has resonated ever since.
Bayes' Theorem in the 21st CenturyThe term "controversial theorem" sounds like an oxymoron, but Bayes' theorem has played this part for two-and-a-half centuries. Twice it has soared to scientific celebrity, twice it has crashed, and it is currently enjoying another boom. The theorem itself is a landmark of logical reasoning and the first serious triumph of statistical inference, yet is still treated with suspicion by most statisticians. There are reasons to believe in the staying power of its current popularity, but also some signs of trouble ahead.
Science 7 June 2013:
Vol. 340 no. 6137 pp. 1177-1178
Mysteries of DevelopmentDevelopment is, literally, the journey of a life time, and it is a trip still as mysterious as it is remarkable. Despite new methods to probe how an animal or plant forms from a single cell, biologists have much to learn about the unimaginably complex process. To identify some of the field's persistent riddles, Senior Editors Beverly Purnell and Stella Hurtley and the news staff of Science have consulted with developmental biologists on our Board of Reviewing Editors and elsewhere. The mysteries offered here are a humbling reminder that our knowledge of development remains to a great extent embryonic.
Why Do So Many Neurons Commit Suicide During Brain Development?
How Do Microbes Shape Animal Development?
How Does Fetal Environment Influence Later Health?
Science 7 June 2013:
Vol. 340 no. 6137 p. 1156
Getting into ShapeAs development progresses from a single fertilized egg to 2, 4, 6, 8, 16 cells, and so on, the early apparent homogeneity soon transitions to cells displaying varied sizes and shapes. Cell adhesion and cortical tension, with their associated forces, contribute to such changes. Crowded cells are pushed and pulled, but some make their own way via cell-autonomous migration or chemotaxis. These events proceed in an amazingly precise, choreographed manner, both temporally and spatially. Distinct germ layers and ultimately the stereotypic body form result, with amazing robustness. This special issue presents exciting advances in understanding morphogenesis, or the development of body shape.
Beverly A. Purnell
Science 7 June 2013:
Vol. 340 no. 6137 p. 1183
Economics: A tale of cash and creditThe macroeconomist Felix Martin covers a vast geographical and historical spread in his argument that we have it all wrong about money. Money: The Unauthorised Biography reveals that credit has a crucial role in society, but that many misunderstandings persist about the relationship of credit to gold or fiat money. The latest views on microeconomic theory get no airing here, yet such developments point to a scientific shift towards an information-processing and network analysis of money and credit markets in a dynamic evolving economy.
Nature 498, 35 (06 June 2013) http://dx.doi.org/10.
Social Media and Information Overload: Survey ResultsA UK-based online questionnaire investigating aspects of usage of user-generated media (UGM), such as Facebook, LinkedIn and Twitter, attracted 587 participants. Results show a high degree of engagement with social networking media such as Facebook, and a significant engagement with other media such as professional media, microblogs and blogs. Participants who experience information overload are those who engage less frequently with the media, rather than those who have fewer posts to read. Professional users show different behaviours to social users. Microbloggers complain of information overload to the greatest extent. Two thirds of Twitter-users have felt that they receive too many posts, and over half of Twitter-users have felt the need for a tool to filter out the irrelevant posts. Generally speaking, participants express satisfaction with the media, though a significant minority express a range of concerns including information overload and privacy.
Kalina Bontcheva, Genevieve Gorrell, Bridgette Wessels
Competition-induced criticality in a model of meme popularityHeavy-tailed distributions of meme popularity occur naturally in a model of meme diffusion on social networks. Competition between multiple memes for the limited resource of user attention is identified as the mechanism that poises the system at criticality. The popularity growth of each meme is described by a critical branching process, and asymptotic analysis predicts power-law distributions of popularity with very heavy tails (exponent $\alpha<2 data.="" empirical="" in="" models="" p="" preferential-attachment="" seen="" similar="" those="" to="" unlike="">
James P. Gleeson, Jonathan A. Ward, Kevin P. O'Sullivan, William T. Lee
International Symposium on Health Systems ComplexityHealth Systems Complexity is a cross-disciplinary research field that takes a unique system dynamics view of health, examining all aspects from the molecular level all the way up to healthcare and governance itself. Health Systems Complexity at the NTU in Singapore is aligned with world-wide initiatives to model patients, like the Virtual Physiological Human, and the health systems in which they function. At the NTU one of the aims is to develop scenario-based decision support systems to assess the influence of healthcare and medication measures on the whole health chain, from the biomedical effects to the impact on social and health policy.
The Health Systems Complexity symposium is pleased to have renowned scholars, scientists, educators and leaders from different corners of the world to talk about how the notion of complexity science can help in understanding health in an integrative way. The symposium presents a revolutionary approach to reforming basic practice and large-scale care delivery, based on the concept of health care as a complex, self-organized, and self-interactive system. The goals of this symposium is to bring together original thinkers who do not shy away from unconventional methods to address the tremendous challenges the growing and aging population of our world is facing.
Venue Education Wing, Level 3, Lecture Room 4, Nanyang Executive Centre, NTU, Singapore
Game of Life on Phyllosilicates: Gliders, Oscillators and Still LifeA phyllosilicate is a sheet of silicate tetrahedra bound by basal oxygens. A phyllosilicate automaton is a regular network of finite state machines --- silicon nodes and oxygen nodes --- which mimics structure of the phyllosilicate. A node takes states 0 and 1. Each node updates its state in discrete time depending on a sum of states of its three (silicon) or six (oxygen) neighbours. Phyllosilicate automata exhibit localizations attributed to Conway's Game of Life: gliders, oscillators, still lifes, and a glider gun. Configurations and behaviour of typical localizations, and interactions between the localizations are illustrated.
Islands and the CounterIntuitive Effect They Have on Tsunamis
Computer simulations show that, far from protecting coastal communities, islands can dramatically amplify the damaging impact of tsunamis.
Adaptive long-range migration promotes cooperation under tempting conditionsMigration is a fundamental trait in humans and animals. Recent studies investigated the effect of migration on the evolution of cooperation, showing that contingent migration favors cooperation in spatial structures. In those studies, only local migration to immediate neighbor sites was considered, while long-range migration has not been considered yet, partly because the long-range migration has been generally regarded as harmful for cooperation as it would bring the population to a well-mixed state that favors defection. In this paper, we studied the effects of adaptive long-range migration on the evolution of cooperation through agent-based simulations of a spatial Prisoner's Dilemma game in which individuals can jump to a farther site if they are surrounded by more defectors. Our results show that adaptive long-range migration strongly promotes cooperation, especially under conditions where the temptation to defect is considerably high. Moreover, we found that cooperation emerges and remains robustly through mutation and migration even from a condition in which only defectors exist. These findings demonstrate the significance of adaptive long-range migration, a naturally observed migration style in human and animal behaviors, for the evolution of cooperation.
Genki Ichinose, Masaya Saito, Hiroki Sayama, David Sloan Wilson
SocInfo 2013We are delighted to welcome the International Conference on Social Informatics (SocInfo 2013) to Kyoto, Japan. The conference will take place from at Clock Tower Centennial Hall, Kyoto University.
Horizons in Social Sciences 2013
Nowadays there is an ongoing intense scientific debate around the definition of the foundational concepts as well as about the most appropriate methodological approaches to deal with the understanding of social dynamics. The challenge of understanding human behaviors is complex and intricate. Humans are intentional (and not necessarily rational) and the dynamics of social behavior are influenced by multitude of factors. In particular, with the advent of the Big Data era– i.e. the explosion of available datasets from technological mediated communication – that challenge has increased its complexity. If on the one hand we can have access to an enormous set of observable social and mobility traces, on the other hand there is a lack of theoretical concepts to ground and interpret data as an expression of individual and social behavior. The event is intended to gather the most proficient scientists and companies working at the edge of the computational social science and big data to detail the new frontiers and challenges with an interdisciplinary, tight and non reductionist approach.The symposium is open to all researchers, scientists and practitioners.
Francis Heylighen: Foundations for a Mathematical Model of the Global Brain
May 17, 2013 Brussels, VUB
Marko Rodriguez: Distributed Graph Analytics with Faunus
Faunus is a graph analytics engine built atop the Hadoop distributed computing platform. The graph representation is a distributed adjacency list, whereby a vertex and its incident edges are co-located with one another. Querying a Faunus graph is possible with a MapReduce-variant of the Gremlin graph traversal language. A Gremlin expression compiles down to a series of MapReduce-steps that are sequence optimized and then executed by Hadoop. Results are stored as transformations to the input graph (graph derivations) or computational side-effects such as aggregates (graph statistics). Beyond querying, a collection of input/output formats are supported which enable Faunus to load/store graphs in the distributed graph database Titan, various common text-based formats stored in HDFS, and via arbitrary user-defined functions. This presentation will focus primarily on Faunus, but will also review the satellite technologies that enable it.
Seminar page: http://ecco.vub.ac.be/?
A Simple Generative Model of Collective Online BehaviourHuman activities---from voter mobilization to political protests---increasingly take place in online environments, providing novel opportunities for relating individual behaviours to population-level outcomes. The recent availability of data sets that capture the behaviour of individuals participating in online social systems has driven the emerging field of computational social science, as large-scale empirical data sets enable the development of detailed computational models of individual and collective behaviour. Given the inherent limitations of observational data, it is crucial to investigate the extent to which models of collective dynamics can distinguish between different individual-level mechanisms. Here we introduce a simple generative model for the collective behaviour of millions of social networking site users who are deciding between different software applications. Our model incorporates two distinct components: one is associated with recent decisions of users, and the other reflects the cumulative popularity of each application. Importantly, although various combinations of the two mechanisms yield long-time behaviour that is consistent with data, only models that strongly emphasize recent popularity of applications over their cumulative popularity reproduce the observed temporal dynamics. Our approach demonstrates the value of even very simple generative models in understanding collective social behaviour, and it highlights the need to address temporal dynamics---not just long-time behaviour---when modelling complex social systems.
James P. Gleeson, Davide Cellai, Jukka-Pekka Onnela, Mason A. Porter, Felix Reed-Tsochas
Computational Social Sciences
Series Editors: Bertino, E., Foster, J., Gilbert, N., Golbeck, J., Kitts, J.A., Liebovitch, L., Matei, S.A., Nijholt, A., Savit, R., Vinciarelli, A.
Computational Social Sciences is explicitly transdisciplinary: quantitative methods from fields such as dynamical systems, artificial intelligence, network theory, agent-based modeling, and statistical mechanics are invoked and combined with state-of-the-art mining and analysis of large data sets to help us understand social agents, their interactions on and offline, and the effect of these interactions at the macro level. Topics include, but are not limited to social networks and media, dynamics of opinions, cultures and conflicts, socio-technical co-evolution and social psychology. Computational Social Sciences will also publish monographs and selected edited contributions from specialized conferences and workshops specifically aimed at communicating new findings to a large transdisciplinary audience. A fundamental goal of the series is to provide a single forum within which commonalities and differences in the workings of this field may be discerned, hence leading to deeper insight and understanding.
Angela Lee Duckworth: The key to success? Grit
Leaving a high-flying job in consulting, Angela Lee Duckworth took a job teaching math to seventh graders in a New York public school. She quickly realized that IQ wasn’t the only thing separating the successful students from those who struggled. Here, she explains her theory of “grit” as a predictor of success.
This blog is home to those not put aback by the complexity inherent to healthcare. This is a site for the complexity as well as system science relishers.
Theories of Learning
Information dissipation as an early-warning signal for the Lehman Brothers collapse in financial time series
In financial markets, participants locally optimize their profit which can result in a globally unstable state leading to a catastrophic change. The largest crash in the past decades is the bankruptcy of Lehman Brothers which was followed by a trust-based crisis between banks due to high-risk trading in complex products. We introduce information dissipation length (IDL) as a leading indicator of global instability of dynamical systems based on the transmission of Shannon information, and apply it to the time series of USD and EUR interest rate swaps (IRS). We find in both markets that the IDL steadily increases toward the bankruptcy, then peaks at the time of bankruptcy, and decreases afterwards. Previously introduced indicators such as ‘critical slowing down’ do not provide a clear leading indicator. Our results suggest that the IDL may be used as an early-warning signal for critical transitions even in the absence of a predictive model.
Information dissipation as an early-warning signal for the Lehman Brothers collapse in financial time series
Rick Quax, Drona Kandhai & Peter M. A. Sloot
Scientific Reports 3, Article number: 1898
Big Data Drives 'National Day Of Civic Hacking'
Nationwide hackathon this weekend encourages coders to use publicly available data to tackle problems ranging from poverty to poultry handling.
LAWS, LANGUAGE and LIFE: Howard Pattee's classic papers on the physics of symbols with contemporary commentary (by Howard Hunt Pattee)
Howard Pattee is a physicist who for many years has taken his own path in studying the physics of symbols, which is now a foundation for biosemiotics. By extending von Neumann’s logical requirements for self-replication, to the physical requirements of symbolic instruction at the molecular level, he concludes that a form of quantum measurement is necessary for life. He explains why all non-dynamic symbolic and informational controls act as special (allosteric) constraints on dynamical systems. Pattee also points out that symbols do not exist in isolation but in coordinated symbol systems we call languages. Such insights turn out to be necessary to situate biosemiotics as an objective scientific endeavor. By proposing a way to relate quiescent symbolic constraints to dynamics, Pattee’s work builds a bridge between physical, biological, and psychological models that are based on dynamical systems theory. Pattee’s work awakes new interest in cognitive scientists, where his recognition of the necessary separation—the epistemic cut—between the subject and object provides a basis for a complementary third way of relating the purely symbolic, computational models of cognition and the purely dynamic, non-representational models. This selection of Pattee’s papers also addresses several other fields, including hierarchy theory, artificial life, self-organization, complexity theory, and the complementary epistemologies of the physical and biological sciences.
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