SEMCIÊNCIA

Power Laws, Weblogs, and Inequality First published February 8, 2003 on the "Networks, Economics, and Culture" mailing list. Subscribe to the mailing list. Version 1.1: Changed 02/10/03 to point to the updated "Blogging Ecosystem" project, and to Jason Kottke's work using Technorati.com data. Added addendum pointing to David Sifry's "Technorati Interesting Newcomers" list, which is in part a response to this article. A persistent theme among people writing about the social aspects of weblogging is to note (and usually lament ) the rise of an A-list, a small set of webloggers who account for a majority of the traffic in the weblog world. This complaint follows a common pattern we've seen with MUDs, BBSes, and online communities like Echo and the WELL. A new social system starts, and seems delightfully free of the elitism and cliquishness of the existing systems. Then, as the new system grows, problems of scale set in. Not everyone can partic...

doi:10.1016/j.tics.2010.02.005 | How to Cite or Link Using DOI Copyright © 2010 Elsevier Ltd All rights reserved. Permissions & Reprints Review Scaling laws in cognitive sciences Christopher T. Kello1, , Gordon D.A. Brown2, Ramon Ferrer-i-Cancho3, John G. Holden4, Klaus Linkenkaer-Hansen5, Theo Rhodes1 and Guy C. Van Orden4 1 Cognitive and Information Sciences University of California , Merced, 5200 North Lake Rd., Merced, CA 95343, USA 2 Department of Psychology, University of Warwick, Coventry CV4 7AL, United Kingdom 3 Department de Llenguatges i Sistemes Informatics, Universitat Politecnica de Catalunya, Campus Nord, Edifici Omega, Jordi Girona Salgado 1-3, 08034 Barcelona, Catalonia, Spain 4 Center for Perception, Action and Cognition, Department of Psychology, University of Cincinnati, PO Box 210376, Cincinnati, OH 45221-0376, USA 5 Department of Integrative Neurophysiology, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, the Netherlands Available online 1 Apri...

Matemáticos [aplicados, físicos e engenheiros] dos EUA desenvolvem fórmula para prever engarrafamentos O Globo  Matemáticos do MIT (Massachusetts Institute of Technology), nos Estados Unidos, desenvolveram uma fórmula para prever o surgimento dos chamados congestionamentos fantasmas - engarrafamentos que surgem de uma hora para outra, sem motivo aparente, em vias com grande concentração de veículos. A equação poderá ajudar na criação de projetos para desenvolvimento de vias com menor potencial de congestionamentos. O modelo descreve como e por que os engarrafamentos são formados. A análise inclui fatores à primeira vista pouco importantes, como freadas súbitas ou a circulação de veículos muito próximos uns dos outros. "As equações, semelhantes às usadas para descrever a mecânica de fluidos, levam em conta fatores como a velocidade de trânsito e densidade do tráfego para calcular as condições para formação e expansão de congestionamentos", diz Morris Flynn, o principal respons...

Estudo: vagalumes sincronizam luzes para conquistar fêmeas 08 de julho de 2010 • 16h50 comentários 1 Notícia Cientistas afirmam que vagalumes sincronizam suas piscadas para que fêmea não confunda as espécies Foto: Getty Images Reduzir Normal Aumentar Imprimir Um novo estudo da universidade de Connecticut, nos Estados Unidos, indica que os vagalumes machos sincronizam suas luzes para atrair as fêmeas. Segundo os cientistas, a sincronia das piscadas ajuda as fêmeas a encontrar os machos da sua própria espécie, e não cruzar com um vagalume de outra. As informações são do Discovery News . Os pesquisadores afirmam que quando a fêmea vê os machos piscando no mesmo padrão, ela pode responder com outro flash para chamar o parceiro. "O que as fêmeas estão fazendo é procurar pelo número e o tempo dos flashes", diz o pesquisador Andrew Moiseff. Os cientistas, para testar a teoria, utilizaram pequenas luzes LED que imitavam os padrões de diferentes espécies. Contudo, os pesquisadores nã...

Por que a maior parte dos blogueiros de ciência e céticos são Popperianos? Kuhn é muito melhor, e pode ser modelado pela sociophysics... Highly connected - a recipe for success Authors: Krzysztof Suchecki, Andrea Scharnhorst, Janusz A. Holyst (Submitted on 5 Jul 2010 (v1), last revised 6 Jul 2010 (this version, v2)) Abstract: In this paper, we tackle the problem of innovation spreading from a modeling point of view. We consider a networked system of individuals, with a competition between two groups. We show its relation to the innovation spreading issues. We introduce an abstract model and show how it can be interpreted in this framework, as well as what conclusions we can draw form it. We further explain how model-derived conclusions can help to investigate the original problem, as well as other, similar problems. The model is an agent-based model assuming simple binary attributes of those agents. It uses a majority dynamics (Ising model to be exact), meaning that individuals attemp...

Para Sandro e Ariadne estudarem (e talvez Paulo e Leonardo): American Journal of Physics, Vol. 72, No. 2, pp. 170–184, February 2004 ©2004 American Association of Physics Teachers. All rights reserved. Up: Issue Table of Contents Go to: Previous Article Next Article Other formats: HTML (smaller files) PDF (158 kB) A hint of renormalization Bertrand Delamotte Laboratoire de Physique Théorique et Hautes Energies, Universités Paris VI, Pierre et Marie Curie, Paris VII, Denis Diderot, 2 Place Jussieu, 75251 Paris Cedex 05, France Received: 28 January 2003; accepted: 15 September 2003 An elementary introduction to perturbative renormalization and renormalization group is presented. No prior knowledge of field theory is necessary because we do not refer to a particular physical theory. We are thus able to disentangle what is specific to field theory and what is intrinsic to renormalization. We link the general arguments and results to real phenomena encountered in particle physics and s...

Em termos de esportes, é bem conhecida a fascinação dos americanos por estatísticas. Neste blog do New York Times você pode encontrar dados estatísticos minuto a minuto das partidas da Copa.  Muito interessante... para um físico estatístico. Idéia para um paper: claramente as estatísticas para intervalos entre posse de bola, chutes a gol, escanteios e faltas não seguem uma distribuição de Poisson, mas lembram uma distribuição com lei de potência (com cut-off de 45 min, claro!) ou talvez uma log-normal. Para um exemplo, veja as estatísticas do jogo Uruguai vs França aqui . Dá para entender algo disso: a probabilidade de um escanteio seguir outro é alta e, quando um time está pressionando outro, os chutes a gol podem sair em sequência (não está claro a origem da distribuição não uniforme de faltas). Na verdade, existem boas razões para se acreditar que o jogo de futebol não é Markoviano nem estacionário. Mas então, seria possível modelar (gerar) essas distribuições de modo simples? Idéi...

Critical mass and the dependency of research quality on group size Ralph Kenna ,  Bertrand Berche (Submitted on 4 Jun 2010) Academic research groups are treated as complex systems and their cooperative behaviour is analysed from a mathematical and statistical viewpoint. Contrary to the naive expectation that the quality of a research group is simply given by the mean calibre of its individual scientists, we show that intra-group interactions play a dominant role. Our model manifests phenomena akin to phase transitions which are brought about by these interactions, and which facilitate the quantification of the notion of critical mass for research groups. We present these critical masses for many academic areas. A consequence of our analysis is that overall research performance of a given discipline is improved by supporting medium-sized groups over large ones, while small groups must strive to achieve critical mass. Comments: 14 pages, 6 figures consisting of 16 panels Subjects: Physic...

New Statistical Method Ranks Sports Players From Different Eras Posted:  02 Mar 2010 09:10 PM PST A new statistical approach reveals the intrinsic talent of sportsmen and women, regardless of the era in which they played. It's a problem that leaves brows furrowed on barstools across the world: how to rate the sportsmen and women of the day against the stars of yesteryear. There's no easy way to make meaningful comparisons when sports change so dramatically over the years. Even in endeavours like baseball where player stats have been meticulously kept for almost a hundred years, comparisons across the decades can be odious. Is it really fair to compare players from the 1920s against those of the last 20 years when so many external factors have changed such as the use of new equipment, better training methods and, of course, performance enhancing drugs? In 1914, the National League Most Valuable Player was Johnny Evers with a batting average of 0.279, 1 Home Run and 40 Runs Batte...

Sociophysics http://www.eoht.info/page/Sociophysics In science , sociophysics is the study of social phenomena from a physics perspective. The subject seems to deal with thermodynamics in part; albeit, the majority of theories in this field seem to be on statistical extrapolations or phase transition models. A noted researcher in the field is physicist Serge Galam claims that he has been in the field of sociophysics since the late 1970s. [1] A noted researcher in this field is Canadian political scientist Paris Arnopoulos and his 1993 book Sociophysics, in which he speculates on heat, pressure, temperature, entropy, and volumes of societies. [3] At the 2008 international workshop on socio physics, at Torino, Italy, the focus was on the statistical physics modeling of large scale social phenomena, such as opinion formation, cultural dissemination, the origin and evolution of language, crowd behavior, social contagion; where it was stated that previous years had witnessed the atte...

Gravity as an entropic force From Wikipedia, the free encyclopedia Verlinde's statistical description of gravity as an entropic force leads to the correct  inverse square distance law of attraction between classical bodies . The hypothesis of  gravity being an entropic force  has a history that goes back to research on  black hole   thermodynamics  by  Bekenstein  and Hawking  in the mid-1970s. These studies suggest a deep connection between  gravity  and thermodynamics. In 1995  Jacobson  demonstrated that the  Einstein equations  describing  relativistic  gravitation can be derived by combining general thermodynamic considerations with the  equivalence principle . [ 1 ]  Subsequently, other physicists have further explored the link between gravity and  entropy . [ 2 ] In 2009,  Erik Verlinde  disclosed a conceptual theory that describes gravity as an entropic force. [ 3 ]  This theory combines the thermodynamic approach to gravity with  Gerardus 't Hooft 's  holographic p...