Power laws, Pareto distributions and Zipf's law

When the probability of measuring a particular value of some quantity varies inversely as a power of that value, the quantity is said to follow a power law, also known variously as Zipf's law or the Pareto distribution. Power laws appear widely in physics, biology, earth and planetary sciences, economics and finance, computer science, demography and the social sciences. For instance, the distributions of the sizes of cities, earthquakes, solar flares, moon craters, wars and people's personal fortunes all appear to follow power laws. The origin of power-law behaviour has been a topic of debate in the scientific community for more than a century. Here we review some of the empirical evidence for the existence of power-law forms and the theories proposed to explain them.Comment: 28 pages, 16 figures, minor corrections and additions in this versio

Community Over Commercialization

Recognizing the power of community is a crucial step in connecting people to free, immediate online access to information

Integration of informal music technologies in secondary school music lessons

date-added: 2011-08-12 11:03:06 +0100 date-modified: 2011-08-12 11:03:38 +0100date-added: 2011-08-12 11:03:06 +0100 date-modified: 2011-08-12 11:03:38 +0100This project was supported by EPSRC grant EP/I001832/1, ‘Musicology for the masses’

Calibration of colloid probe cantilevers using the dynamic viscous response of a confined liquid

A method is described to determine the spring constant of colloid probe cantilevers used in force measurements with the atomic force microscope. An oscillatory drive applied to the substrate is coupled by viscous interactions to the colloid probe. The dynamic response of the probe, which is unaffected by static interactions, is then used to determine the spring constant of the cantilever. Thus an accurate calibration of the spring constant may be performed simultaneously with a normal colloidal probe force measurementin situ.S.N. and S.B. acknowledge the support of the Center for Multiphase Processes, a Special Research Center of the Australian Research Council. V.C. acknowledges support from the Australian Research Council for the provision of a Postdoctoral Fellowship

Inflammation produces catecholamine resistance in obesity via activation of PDE3B by the protein kinases IKKε and TBK1.

Obesity produces a chronic inflammatory state involving the NFκB pathway, resulting in persistent elevation of the noncanonical IκB kinases IKKε and TBK1. In this study, we report that these kinases attenuate β-adrenergic signaling in white adipose tissue. Treatment of 3T3-L1 adipocytes with specific inhibitors of these kinases restored β-adrenergic signaling and lipolysis attenuated by TNFα and Poly (I:C). Conversely, overexpression of the kinases reduced induction of Ucp1, lipolysis, cAMP levels, and phosphorylation of hormone sensitive lipase in response to isoproterenol or forskolin. Noncanonical IKKs reduce catecholamine sensitivity by phosphorylating and activating the major adipocyte phosphodiesterase PDE3B. In vivo inhibition of these kinases by treatment of obese mice with the drug amlexanox reversed obesity-induced catecholamine resistance, and restored PKA signaling in response to injection of a β-3 adrenergic agonist. These studies suggest that by reducing production of cAMP in adipocytes, IKKε and TBK1 may contribute to the repression of energy expenditure during obesity. DOI: http://dx.doi.org/10.7554/eLife.01119.001

Linear enamel hypoplasia as a proxy for environmental stress in fossil apes

1 online resource (iii, 51 pages) : colour illustrationsIncludes abstract.Includes bibliographical references (pages 43-51).The Anthropocene, our current geological era, is defined by increased anthropogenic environmental alteration that is reducing great ape populations globally. As this occurs, there becomes an increased need to not only understand how great apes are being impacted by the changing environment, but how they will respond to this change. The focus of this research is to use the dental developmental defect Linear Enamel Hypoplasia in the Late-Miocene great ape Hispanopithecus crusafonti to reconstruct Late-Miocene seasonality. These patterns are then analyzed in relation to previous research on Late-Miocene climate to understand how H. crusafonti responded to increasingly variable seasonality. The Late-Miocene, similarly to the Anthropocene, faced climatic upheaval that resulted in the extinction of many great ape species. Seasonal bouts of physiological stress are expressed through enamel depressions in fossil teeth. Through microscopic analysis and reconstruction of the duration of annual stress intervals, the irregularity of Late-Miocene seasonality is identified. These findings are applied to a comparison with the extant great ape, Pongo, who expresses many of the same specialized characteristics as H. crusafonti; features like morphology, diet, and ecology are influenced by their similar warm and tropical forest habitats and are therefore reflected in both species. It was determined that the primary factors influencing the decline of both fossil and extant great apes is the frequency of stress events and great ape specialization, which limits adaptability during seasonal and environmental variability. This constrains them and bases their survival on specific environmental conditions that are not conducive to the rapidly changing climate of the Anthropocene. This is likely what led to the extinction of H. crusafonti and what is currently severely decreasing orangutan and great ape populations