Power Law Distribution of the Duration and Magnitude of Recessions in Capitalist Economies : Breakdown of Scaling

Power law distributions of macroscopic observables are ubiquitous in both the natural and social sciences. They are indicative of correlated, cooperative phenomena between groups of interacting agents at the microscopic level. In this paper we argue that when one is considering aggregate macroeconomic data (annual growth rates in real per capita GDP in the seventeen leading capitalist economies from 1870 through to 1994) the magnitude and duration of recessions over the business cycle do indeed follow power law like behaviour for a significant proportion of the data (demonstrating the existence of cooperative phenomena amongst economic agents). Crucially, however, there are systematic deviations from this behaviour when one considers the frequency of occurrence of large recessions. Under these circumstances the power law scaling breaks down. It is argued that it is the adaptive behaviour of the agents (their ability to recognise the changing economic environment) which modifies their cooperative behaviour.Comment: 17 pages, 6 figures, Accepted for Publication in Physica

Navigating the Photographic Periphery: Vivian Maier and Amateur Photography

This thesis is concerned with the ways in which women are subject to and limited by gendered categorisations of photographic practice. The photography of Vivian Maier (1926-2009) will form a case study arguing that Maier’s photographic practice and posthumous recognition is representative of the marginalisation of women in photography, which has in turn led to an erasure of women photographers in photographic histories. The impetus for the construction of a reputation as a ‘street photographer’ for Maier is located in the economic imperatives governing the collectors and exhibitors of her work, whilst the necessary attributes of that reputation are determined by canonical values that eschew difference. The thesis will re-think the binaries of inside-outside and amateur-professional using Foteini Vlachou’s conceptualisation of centres and peripheries put forth in her article, Why Spatial? Time and the Periphery (2016) in order to show that the historiography of American photography is underpinned by sexual difference

Random Matrix Theory and the Failure of Macroeconomic Forecasts

By scientific standards, the accuracy of short-term economic forecasts has been poor, and shows no sign of improving over time. We form a delay matrix of time-series data on the overall rate of growth of the economy, with lags spanning the period over which any regularity of behaviour is postulated by economists to exist. We use methods of random matrix theory to analyse the correlation matrix of the delay matrix. This is done for annual data from 1871 to 1994 for 17 economies, and for post-war quarterly data for the US and the UK. The properties of the eigenvalues and eigenvectors of these correlation matrices are similar, though not identical, to those implied by random matrix theory. This suggests that the genuine information content in economic growth data is low, and so forecasting failure arises from inherent properties of the data.Comment: 15 Pages, 2 Figure

The Organizational Effect of Prenatal Testosterone Upon Gender Role Identity and Mental Toughness in Female Athletes

Research has identified a correlation between prenatal markers of testosterone (2D4D) and sport performance. This relationship is thought to be explained by several important psychophysiological variables such as physical fitness and mental toughness. The current study sought to add to this body of research by examining the differences between high and low 2D4D, in measures of gender identity (Bem Sex Role Inventory) and mental toughness (the 48-item version of the Mental Toughness Questionnaire). A sample of 116 recreational (n = 59) and competitive netballers (n = 57) completed the psychological measures and provided right-hand scans from which 2D4D ratio measures were drawn. The key results included a large effect of low digit ratio on emotional control, life control, and interpersonal confidence. These findings suggest that 2D4D could provide a marker for sporting potential and mental toughness in female sport participants. However, future research may wish to establish the relative contribution of prenatal factors (e.g., 2D4D) and socialization factors (e.g., involvement in a sporting context) on sporting ability and related psychological variables

Entropy of particle packings : an illustration on a toy model

A toy model of particles packings is presented, which consists in arranging hexagons on a triangular lattice according to local stability rules. The number of stable packings is analytically computed and found to grow exponentially with the size of the lattice, which illustrates the concept of packing entropy first proposed by Edwards and collaborators. The analysis is carried out for both the monodispersed case and the more interesting, i.e. more disordered, bidispersed case.Comment: 20 pages, 7 figures; to appear in Physica

The Convergence of European Business Cycles 1978-2000

The degree of convergence of the business cycles of the economies of the European Union is a key policy issue. In particular, a substantial degree of convergence is needed if the European Central Bank is to be capable of setting a monetary policy which is appropriate to the stage of the cycle of the Euro zone economies. We consider the annual rates of real GDP growth on a quarterly basis in the large core economies of the EU (France, Germany and Italy, plus the Netherlands) over the period 1978Q1 - 2000Q3. An important empirical question is the degree to which the correlations between these growth rates contain true information rather than noise. The technique of random matrix theory is able to answer this question, and has been recently applied successfully in the physics journals to financial markets data. We find that the correlations between the growth rates of the core EU economies contain substantial amounts of true information, and exhibit considerable stability over time. Even in the late 1970s and early 1980s, these economies moved together closely over the course of the business cycle. There was a slight loosening at the time of German re-unification, but the economies are now, if anything, even more closely correlated. In contrast, the results obtained with a data set of the EU core plus the UK show no such trend. In the late 1970s and early 1980s, the UK economy did exhibit some degree of correlation with those of the core EU. However, there is no clear evidence to suggest that the UK business cycle has moved more closely into line with that of the core EU economies over the 1978-2000 period.Comment: 22 page

Vortices in vibrated granular rods

We report the experimental observation of novel vortex patterns in vertically vibrated granular rods. Above a critical packing fraction, moving ordered domains of nearly vertical rods spontaneously form and coexist with horizontal rods. The domains of vertical rods coarsen in time to form large vortices. We investigate the conditions under which the vortices occur by varying the number of rods, vibration amplitude and frequency. The size of the vortices increases with the number of rods. We characterize the growth of the ordered domains by measuring the area fraction of the ordered regions as a function of time. A {\em void filling} model is presented to describe the nucleation and growth of the vertical domains. We track the ends of the vertical rods and obtain the velocity fields of the vortices. The rotation speed of the rods is observed to depend on the vibration velocity of the container and on the packing. To investigate the impact of the direction of driving on the observed phenomena, we performed experiments with the container vibrated horizontally. Although vertical domains form, vortices are not observed. We therefore argue that the motion is generated due to the interaction of the inclination of the rods with the bottom of a vertically vibrated container. We also perform simple experiments with a single row of rods in an annulus. These experiments directly demonstrate that the rod motion is generated when the rods are inclined from the vertical, and is always in the direction of the inclination.Comment: 6 pages, 10 figure, 2 movies at http://physics.clarku.edu/vortex uses revtex

Properties of layer-by-layer vector stochastic models of force fluctuations in granular materials

We attempt to describe the stress distributions of granular packings using lattice-based layer-by-layer stochastic models that satisfy the constraints of force and torque balance and non-tensile forces at each site. The inherent asymmetry in the layer-by-layer approach appears to lead to an asymmetric force distribution, in disagreement with both experiments and general symmetry considerations. The vertical force component probability distribution is robust and in agreement with predictions of the scalar q model while the distribution of horizontal force components is qualitatively different and depends on the details of implementation.Comment: 18 pages, 12 figures (with subfigures), 1 table. Uses revtex, epsfig,subfigure, and cite. Submitted to PRE. Plots have been bitmapped. High-resolution version is available. Email [email protected] or download from http://rainbow.uchicago.edu/~mbnguyen/research/vm.htm

Cracking Piles of Brittle Grains

A model which accounts for cracking avalanches in piles of grains subject to external load is introduced and numerically simulated. The stress is stochastically transferred from higher layers to lower ones. Cracked areas exhibit various morphologies, depending on the degree of randomness in the packing and on the ductility of the grains. The external force necessary to continue the cracking process is constant in wide range of values of the fraction of already cracked grains. If the grains are very brittle, the force fluctuations become periodic in early stages of cracking. Distribution of cracking avalanches obeys a power law with exponent $\tau = 2.4 \pm 0.1$.Comment: RevTeX, 6 pages, 7 postscript figures, submitted to Phys. Rev.