Bull Int Stat Inst

Over the last 100 years, a large number of distributions has been proposed for the modeling of size phenomena, notably the size distribution of personal incomes (see, for example, Kleiber and Kotz, 2003). The most widely known of these models are the Pareto and the lognormal distributions; however, both are known to be not flexible enough for the modeling of income data. Here we consider a generalization of the lognormal distribution for which the available literature is mainly in Italian

Superlinear Scaling for Innovation in Cities

Superlinear scaling in cities, which appears in sociological quantities such as economic productivity and creative output relative to urban population size, has been observed but not been given a satisfactory theoretical explanation. Here we provide a network model for the superlinear relationship between population size and innovation found in cities, with a reasonable range for the exponent.Comment: 5 pages, 5 figures, 1 table, submitted to Phys. Rev. E; references corrected; figures corrected, references and brief discussion adde

“It gave me something big in my life to wonder and think about which took over the space … and not MS”: Managing well-being in multiple sclerosis through art-making

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2014 Informa UK Ltd.Background and aim: Individuals living with Multiple Sclerosis (MS) often face progressive loss of function, uncertainty and disruption to self-image and valued roles. Previous studies show that creative self-expression is valued by some people living with long-term illness, yet its meaning for people living with MS is unclear. This research study explored the meanings of leisure-based visual art-making for people living with MS. Method: This qualitative study followed guidelines for Interpretative Phenomenological Analysis (IPA). Single semi-structured interviews were conducted with five adults (2 males; 3 females; 40–65 years), recruited from MS Ireland. Findings: Participants valued art-making for contributing to a more satisfying way of life; for filling occupational voids and using time well. Deep immersion offered respite from worry about illness. Creative classes offered social camaraderie and opportunities for learning and development. Art-making processes and products were highly affirmative, increasing emotional well-being and promoting self-worth. Most felt that they expressed valued aspects of self through their art. Art-making appeared to assist with identity maintenance, accommodating functional losses associated with MS whilst opening “new doors”. Conclusion: Art-making offered a multi-faceted means of supporting identity and increasing fulfilment in lives that were restricted in many ways by MS

Associations Between Experienced and Internalized HIV Stigma, Adversarial Growth, and Health Outcomes in a Nationwide Sample of People Aging with HIV in Germany

HIV-related stigmatization and adversarial growth are known to influence health outcomes in people living with HIV. But not much is known how these psychosocial factors are related to each other and how they interact to influence health outcomes. We tested whether the effect of experienced and internalized stigma on mental health and self-rated health is mediated by adversarial growth, and whether each of these factors is uniquely associated with health outcomes. In our sample of 839 people aging with HIV in Germany based on a cross-sectional study design we did not find an indirect effect of experienced HIV stigma on health outcomes and a very small indirect effect of internalized HIV stigma. All variables were significant predictors of health outcomes in multiple regression analyses

On neoclassical impurity transport in stellarator geometry

The impurity dynamics in stellarators has become an issue of moderate concern due to the inherent tendency of the impurities to accumulate in the core when the neoclassical ambipolar radial electric field points radially inwards (ion root regime). This accumulation can lead to collapse of the plasma due to radiative losses, and thus limit high performance plasma discharges in non-axisymmetric devices.\\ A quantitative description of the neoclassical impurity transport is complicated by the breakdown of the assumption of small $\mathbf{E}\times \mathbf{B}$ drift and trapping due to the electrostatic potential variation on a flux surface $\tilde{\Phi}$ compared to those due to the magnetic field gradient. The present work examines the impact of this potential variation on neoclassical impurity transport in the Large Helical Device (LHD) stellarator. It shows that the neoclassical impurity transport can be strongly affected by $\tilde{\Phi}$. The central numerical tool used is the $\delta f$ particle in cell (PIC) Monte Carlo code EUTERPE. The $\tilde{\Phi}$ used in the calculations is provided by the neoclassical code GSRAKE. The possibility of obtaining a more general $\tilde{\Phi}$ self-consistently with EUTERPE is also addressed and a preliminary calculation is presented.Comment: 11 pages, 15 figures, presented at Joint Varenna-Lausanne International Workshop on Theory of Fusion Plasmas, 2012. Accepted for publication to Plasma Phys. and Control. Fusio

How self-organization can guide evolution

Self-organization and natural selection are fundamental forces that shape the natural world. Substantial progress in understanding how these forces interact has been made through the study of abstract models. Further progress may be made by identifying a model system in which the interaction between self-organization and selection can be investigated empirically. To this end, we investigate how the self-organizing thermoregulatory huddling behaviours displayed by many species of mammals might influence natural selection of the genetic components of metabolism. By applying a simple evolutionary algorithm to a wellestablished model of the interactions between environmental, morphological, physiological and behavioural components of thermoregulation, we arrive at a clear, but counterintuitive, prediction: rodents that are able to huddle together in cold environments should evolve a lower thermal conductance at a faster rate than animals reared in isolation. The model therefore explains how evolution can be accelerated as a consequence of relaxed selection, and it predicts how the effect may be exaggerated by an increase in the litter size, i.e. by an increase in the capacity to use huddling behaviours for thermoregulation. Confirmation of these predictions in future experiments with rodents would constitute strong evidence of a mechanism by which self-organization can guide natural selection

Can greater muscularity in larger individuals resolve the 3/4 power-law controversy when modelling maximum oxygen uptake?

BACKGROUND: The power function relationship, MR = a.m(b), between metabolic rate (MR) and body mass m has been the source of much controversy amongst biologists for many years. Various studies have reported mass exponents (b) greater than the anticipated 'surface-area' exponent 0.67, often closer to 0.75 originally identified by Kleiber. AIM: The study aimed to provide a biological explanation for these 'inflated' exponents when modelling maximum oxygen uptake (max), based on the observations from this and previous studies that larger individuals develop disproportionately more muscle mass in the arms and legs. RESEARCH DESIGN AND SUBJECTS: A cross-sectional study of 119 professional soccer players from Croatia aged 18-34 was carried out. RESULTS: Here we confirm that the power function relationship between max and body mass of the professional soccer players results in an 'inflated' mass exponent of 0.75 (95% confidence interval from 0.56 to 0.93), but also the larger soccer players have disproportionately greater leg muscle girths. When the analysis was repeated incorporating the calf and thigh muscle girths rather than body mass as predictor variables, the analysis not only explained significantly more of the variance in max, but the sum of the exponents confirmed a surface-area law. CONCLUSIONS: These findings confirm the pitfalls of fitting body-mass power laws and suggest using muscle-girth methodology as a more appropriate way to scale or normalize metabolic variables such as max for individuals of different body sizes