Complexity at large
2011; Hindawi Publishing Corporation; Volume: 16; Issue: 4 Linguagem: Inglês
10.1002/cplx.20374
ISSN1099-0526
Autores Tópico(s)Cognitive Science and Mapping
ResumoThe following news item is taken in part from the October 1, 2010 issue of Science titled “Complex Systems View of Educational Policy Research,” by S. Maroulis, R. Guimerà, H. Petry, M. J. Stringer, L. M. Gomez, L. A. N. Amaral, and U. Wilensky. Education researchers have struggled for decades with questions such as “why are troubled schools so difficult to improve?” or “why is the achievement gap so hard to close?” We argue here that conceptualizing schools and districts as complex adaptive systems, composed of many networked parts that give rise to emergent patterns through their interactions (1), holds promise for understanding such important problems. Although there has been considerable research on the use of complex system's ideas and methods to help students learn science content (2), only recently researchers have begun to apply these tools to issues of educational policy. A link to this article can be found at http://dx.doi.org/10.1126/science.1195153. The following news item is taken in part from the September 7, 2010 issue of PLoS Biol titled “Arms and the Man: The Problem of Symmetric Growth,” by Lewis Wolpert. The external features of our bodies are specified in the embryo and then grow for some 16 years, yet many are remarkably symmetrical. Just consider how similar in size and shape your two ears are, and if you extend your arms, you will likely find that they, too, are similar in length, even though they grew independently from tiny buds in the embryo. Their length matches with an accuracy of about 0.2% yet there is no known communication between the limbs during growth. You will find the same holds for your two forefingers as it does for the size of internal body organs such as the kidneys and lungs. How is such coordination achieved? Although we have a reasonably good understanding of how our limbs grow, we know relatively little about how their growth is so reliably controlled. A link to this article can be found at http://dx.doi.org/10.1371/journal.pbio.1000477. The following news item is taken in part from the November, 2010 issue of Behavioral Ecology and Sociobiology titled “Quantifying social synergy in insect and human societies,” by Klaus Jaffe. What are the benefits of society? What are the adaptive advantages of social behavior? The fact that societies exist suggest that society favors synergies in the interactions between individuals. One such synergy or adaptive advantage might be the increased efficiency in the use of scarce resources. This has been postulated to occur in the “metabolic scaling law,” where larger organisms with more cells consume less energy per unit mass than smaller organisms. Here, I develop a similar scale-free index for social synergy applicable to energy consumption and apply it to social insect colonies and human cities. The results show that all societies studied increase the efficiency of energy consumption with increased sizes. A link to this article can be found at http://dx.doi.org/10.1007/s00265-010-1059-0. The following news item is taken in part from the September 14, 2010 issue of PLoS Biol titled “A Mixture of “Cheats” and “Co-Operators” Can Enable Maximal Group Benefit,” by R. Craig MacLean, Ayari Fuentes-Hernandez, Duncan Greig, Laurence D. Hurst, and Ivana Gudelj. The world is best off, it is usually presumed, when everyone cooperates. However, we discovered in a laboratory experiment involving yeasts that a population can grow more and faster when there is a mix of “cheats” and “cooperators.” We find three conditions required to recover the unexpected result: (1) the cooperators should get more food than “cheats” (e.g., if the two are not perfectly mixed together), (2) food is used more efficiently when there is a famine than when there is a feast, and (3) the amount of “cooperation” given should not accurately match the amount needed. We argue that all three are likely not to be peculiar to yeast, suggesting that “cheats” may be good for a group in many cases. A link to this article can be found at http://dx.doi.org/10.1371/journal.pbio.1000486. The following news item is taken in part from the October 21, 2010 issue of Nature titled “Synthetic biology: Living quarters,” by Rachel Armstrong and Neil Spiller. All complex life is composed of eukaryotic (nucleated) cells. The eukaryotic cell arose from prokaryotes just once in four billion years, and otherwise prokaryotes show no tendency to evolve greater complexity. Why not? Prokaryotic genome size is constrained by bioenergetics. The endosymbiosis that gave rise to mitochondria restructured the distribution of DNA in relation to bioenergetic membranes, permitting a remarkable 200,000-fold expansion in the number of genes expressed. This vast leap in genomic capacity was strictly dependent on mitochondrial power, and prerequisite to eukaryote complexity: the key innovation en route to multicellular life. A link to this article can be found at http://dx.doi.org/10.1038/467916a. The following news item is taken in part from the October 21, 2010 issue of Nature titled “Cities: The urban equation.” After spending tens of thousands of years living mostly in small settlements, humans have entered an urban stage of evolution. As of 2008, more than half the world's people live in cities, and the urban population is swelling by 1 million every week. By 2030, almost 6 in 10 people will live in metropolitan areas, which exert a powerful pull as economic and social magnets. A link to this article can be found at http://dx.doi.org/10.1038/467899a. The following news item is taken in part from the October 21, 2010 issue of Nature titled “A unified theory of urban living,” by Luis Bettencourt and Geoffrey West. Cities are complex systems whose infrastructural, economic, and social components are strongly interrelated and, therefore, difficult to understand in isolation. The many problems associated with urban growth and global sustainability, however, are typically treated as independent issues. This frequently results in ineffective policy and often leads to unfortunate and sometimes disastrous unintended consequences. Policies meant to control population movements and the spread of slums in megacities, or to reverse urban decay, have largely proven ineffective or counterproductive, despite huge expenditure. A link to this article can be found at http://dx.doi.org/10.1038/467912a. The following news item is taken in part from the October 14, 2010 issue of arXiv titled “Twitter mood predicts the stock market,” by Johan Bollen, Huina Mao, and Xiao-Jun Zeng. Behavioral economics tells us that emotions can profoundly affect individual behavior and decision-making. Does this also apply to societies at large, that is, can societies experience mood states that affect their collective decision making? By extension is the public mood correlated or even predictive of economic indicators? Here, we investigate whether measurements of collective mood states derived from large-scale Twitter feeds are correlated to the value of the Dow Jones industrial average (DJIA) over time. We find an accuracy of 87.6% in predicting the daily up and down changes in the closing values of the DJIA and a reduction of the mean average percentage error by more than 6%. A link to this article can be found at http://arXiv.org/abs/1010.3003. The following news item is taken in part from the October 11, 2010 issue of PNAS titled “Spontaneous emergence of social influence in online systems,” by Jukka-Pekka Onnela and Felix Reed-Tsochas. Social influence drives both offline and online human behavior. It pervades cultural markets and manifests itself in the adoption of scientific and technical innovations as well as the spread of social practices. Prior empirical work on the diffusion of innovations in spatial regions or social networks has largely focused on the spread of one particular technology among a subset of all potential adopters. Here, we choose an online context that allows us to study social influence processes by tracking the popularity of a complete set of applications installed by the user population of a social networking site, thus capturing the behavior of all individuals who can influence each other in this context. A link to this article can be found at http://dx.doi.org/10.1073/pnas.0914572107. The following news item is taken in part from the October 21, 2010 issue of Nature titled “The energetics of genome complexity,” by Nick Lane and William Martin. All complex life is composed of eukaryotic (nucleated) cells. The eukaryotic cell arose from prokaryotes just once in four billion years, and otherwise prokaryotes show no tendency to evolve greater complexity. Why not? Prokaryotic genome size is constrained by bioenergetics. The endosymbiosis that gave rise to mitochondria restructured the distribution of DNA in relation to bioenergetic membranes, permitting a remarkable 200,000-fold expansion in the number of genes expressed. This vast leap in genomic capacity was strictly dependent on mitochondrial power, and prerequisite to eukaryote complexity: the key innovation en route to multicellular life. A link to this article can be found at http://dx.doi.org/10.1038/nature09486. The following news item is taken in part from the October 29, 2010 issue of Science titled “What Is Epigenetics?” by Guy Riddihough and Laura M. Zahn. The cells in a multicellular organism have nominally identical DNA sequences (and therefore the same genetic instruction sets), yet maintain different terminal phenotypes. This nongenetic cellular memory, which records developmental and environmental cues (and alternative cell states in unicellular organisms), is the basis of epi-(above)-genetics. A link to this article can be found at http://dx.doi.org/10.1126/science.330.6004.611. The following news item is taken in part from the November, 2010 issue of Evolution titled “Is Life Impossible? Information, Sex, and the Origin of Complex Organisms,” by Joel R. Peck and David Waxman. The earliest organisms are thought to have had high mutation rates. It has been asserted that these high mutation rates would have severely limited the information content of early genomes. This has led to a well-known “paradox” because, in contemporary organisms, the mechanisms that suppress mutations are quite complex and a substantial amount of information is required to construct these mechanisms. The paradox arises because it is not clear how efficient error-suppressing mechanisms could have evolved and, thus, allowed the evolution of complex organisms, at a time when mutation rates were too high to permit the maintenance of very substantial amounts of information within genomes. Here, we use concepts from the formal theory of information to calculate the amount of genomic information that can be maintained. A link to this article can be found at http://dx.doi.org/10.1111/j.1558-5646.2010.01074.x. The following news item is taken in part from the November 4, 2010 issue of Nature titled “Higher rates of sex evolve in spatially heterogeneous environments,” by Lutz Becks and Aneil F. Agrawal. The evolution and maintenance of sexual reproduction has puzzled biologists for decades Here we use the rotifer, Brachionus calyciflorus, which is capable of both sexual and asexual reproduction, to test recent theory predicting that there is more opportunity for sex to evolve in spatially heterogeneous environments. A link to this article can be found at http://dx.doi.org/10.1038/nature09449. The following news item is taken in part from the October 24, 2010 issue of arXiv titled “Collective motion,” by Tamás Vicsek and Anna Zafiris. We review the observations and the basic laws describing the essential aspects of collective motion—being one of the most common and spectacular manifestation of coordinated behavior. Our aim is to provide a balanced discussion of the various facets of this highly multidisciplinary field, including experiments, mathematical methods, and models for simulations, so that readers with a variety of background could get both the basics and a broader, more detailed picture of the field. The observations we report on include systems consisting of units ranging from macromolecules through metallic rods and robots to groups of animals and people. A link to this article can be found at http://dx.doi.org/10.1038/nature09449. The following news item is taken in part from the December, 2010 issue of Cognitive Systems Research titled “Recognizing group cognition,” by Georg Theiner, Colin Allen, and Robert L. Goldstone. In this article, we approach the idea of group cognition from the perspective of the “extended mind” thesis, as a special case of the more general claim that systems larger than the individual human, but containing that human, are capable of cognition. Instead of deliberating about “the mark of the cognitive”, our discussion of group cognition is tied to particular cognitive capacities. We review recent studies of group problem solving and group memory, which reveal that specific cognitive capacities that are commonly ascribed to individuals are also aptly ascribed at the level of groups. Group cognition is thus an emergent phenomenon in the sense of Wimsatt. A link to this article can be found at http://dx.doi.org/10.1016/j.cogsys.2010.07.002. The following news item is taken in part from the December 28, 2010 issue of Phil. Trans. R. Soc. A titled “Complex dynamics of life at different scales,” by Celia Anteneodo and Marcos G.E. da Luz. The special issue, Complex dynamics of life at different scales: from genomic to global environmental issues, puts together a set of comprehensive works in complex systems research focusing life at different scales: viral quasi-species, genetic regulatory dynamics; cellular signaling, blood flows; neuronal response, the brain; population dynamics and epidemics; social and economical systems; the environment. Besides furnishing new relevant results on those subjects, the selected works provide an overview of the more recent techniques and methodological approaches to tackle the study of the complex phenomenon of life. A link to this article can be found at http://rsta.royalsocietypublishing.org/site/issues/complex_dynamics_life.xhtml. The following news item is taken in part from the December 28, 2010 issue of Phil. Trans. R. Soc. A titled “Complex dynamics of our economic life on different scales: insights from search engine query data,” by Tobias Preis, Daniel Reith, and H. Eugene Stanley. Search engine query data deliver insight into the behavior of individuals who are the smallest possible scale of our economic life. Individuals are submitting several hundred million search engine queries around the world each day. We study weekly search volume data for various search terms from 2004 to 2010 that are offered by the search engine Google. We find clear evidence that weekly transaction volumes of S&P 500 companies are correlated with weekly search volume of corresponding company names. Furthermore, we find a clear tendency that search volume time series and transaction volume time series show recurring patterns. A link to this article can be found at http://dx.doi.org/10.1098/rsta.2010.0284. The following news item is taken in part from the November 12, 2010 issue of Science titled “Irremediable Complexity?” by Michael W. Gray, Julius Lukeš, John M. Archibald, Patrick J. Keeling, and W. Ford Doolittle. Many of the cell's macromolecular machines appear gratuitously complex, comprising more components than their basic functions seem to demand. How can we make sense of this complexity in the light of evolution? One possibility is a neutral ratchet-like process described more than a decade ago, subsequently called constructive neutral evolution. This model provides an explanatory counterpoint to the selectionist or adaptationist views that pervade molecular biology. A link to this article can be found at http://dx.doi.org/10.1126/science.1198594. The following news item is taken in part from the November 18, 2010 issue of arXiv titled “Life is physics: evolution as a collective phenomenon far from equilibrium,” by Nigel Goldenfeld and Carl Woese. Evolution is the fundamental physical process that gives rise to biological phenomena. Yet it is widely treated as a subset of population genetics, and thus, its scope is artificially limited. As a result, the key issues of how rapidly evolution occurs, and its coupling to ecology have not been satisfactorily addressed and formulated. The lack of widespread appreciation for, and understanding of, the evolutionary process has arguably retarded the development of biology as a science, with disastrous consequences for its applications to medicine, ecology, and the global environment. This review focuses on evolution as a problem in nonequilibrium statistical mechanics. A link to this article can be found at http://arXiv.org/abs/1011.4125. IEEE Symposium Series on Computational Intelligence - SSCI 2011, Paris, France, 2011/04/11-15 http://www.ieee-ssci.org/ EVOSTAR 2011, Torino, Italy, 2011/4/27-29 http://evostar.org/ International Conference on Complex Systems (ICCS 2011), Boston, MA, USA, 2011/06/26-07/01 http://www.necsi.edu/events/iccs2011/ GECCO 2011: Genetic and Evolutionary Computation Conference, Dublin, Ireland, 2011/07/12-16 http://www.sigevo.org/gecco-2011/ IJCAI 2011, the 22nd International Joint Conference on Artificial Intelligence, Barcelona, Spain, 2011/07/16-22 http://ijcai-11.iiia.csic.es/ Third International Workshop on nonlinear Dynamics and Synchronization—INDS'11 Sixteenth International Symposium on Theoretical Electrical Engineering—ISTET'11, Klagenfurt am Wörthersee, Austria, 2011/07/25-27 http://inds11.uni-klu.ac.at/ ECAL 11: European Conference on Artificial Life, Paris, France, 2011/08/8-12 http://www.ecal11.org/ European Conference on Complex Systems 2011, Vienna, Austria, 2011/09/12-16 http://eccs2011.eu/
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