Book Review

Welfare\u27s Forgotten Past: A Socio-Legal History of the Poor Law is a timely reminder of society\u27s legal duty to the poor. In an era of global economic turmoil, with recent welfare reform and heated debates over the extension of unemployment benefits here in the United States, it is easy to forget that laws for the relief of poverty have roots reaching back more than 400 years. Author Lorie Charlesworth, Reader in Law and History at Liverpool John Moores University, focuses her book on the poor law-a historical, English system derived largely from the seventeenth-century laws of settlement and removal, which provided support for the settled poor within their home parishes

A Proposed Solution to the Scholarly Communication Crisis

After reviewing the history and parameters of the scholarly communications crisis, particularly in regard to skyrocketing prices for journals in the natural sciences, the author reviews and rejects previously attempted solutions. He then employs the principles of game theory in proposing a new solution to the crisis

Friends without Benefits: How States Systematically Shortchange Teachers' Retirement and Threaten Their Retirement Security

Americans are often reminded that it's never too soon to start saving for retirement. Many of the nation's public school teachers are doing just that -- buying into their state pension system with plans to retire comfortably. However, this new study estimates that nearly 50 percent of all public school teachers will not qualify for even a minimal pension benefit, and less than 20 percent will stay in the profession long enough to earn a normal retirement benefit.This Joyce-funded report demonstrates the consequences of poorly structured state and city policies that can exacerbate retirement insecurity for our nation's teachers. For example, an individual teacher could forfeit up to 6.5 percent of her annual salary for one year, or, due to compound interest, 22.6 percent of her annual salary after three years according to Bellwether's analysis. To put these penalties in dollar terms, a hypothetical teacher earning $40,000 a year could face a savings penalty of$2,601 for teaching only one year and $9,035 if she left after three years. This money stays with the pension funds and is used to supplement the pensions of the remaining teachers.Tackling the pension system is critical for reducing teacher turnover and retaining the profession's most talented educators. Several policy solutions are offered

Better Benefits: Reforming Teacher Pensions for a Changing Work Force

Explains how defined-benefit pension plans create barriers to attracting, retaining, and distributing effective teachers equitably. Proposes reforms including changing the benefit formula or structure, limiting political pressure, and phasing in changes

A primer of swarm equilibria

We study equilibrium configurations of swarming biological organisms subject to exogenous and pairwise endogenous forces. Beginning with a discrete dynamical model, we derive a variational description of the corresponding continuum population density. Equilibrium solutions are extrema of an energy functional, and satisfy a Fredholm integral equation. We find conditions for the extrema to be local minimizers, global minimizers, and minimizers with respect to infinitesimal Lagrangian displacements of mass. In one spatial dimension, for a variety of exogenous forces, endogenous forces, and domain configurations, we find exact analytical expressions for the equilibria. These agree closely with numerical simulations of the underlying discrete model.The exact solutions provide a sampling of the wide variety of equilibrium configurations possible within our general swarm modeling framework. The equilibria typically are compactly supported and may contain $\delta$-concentrations or jump discontinuities at the edge of the support. We apply our methods to a model of locust swarms, which are observed in nature to consist of a concentrated population on the ground separated from an airborne group. Our model can reproduce this configuration; quasi-two-dimensionality of the model plays a critical role.Comment: 38 pages, submitted to SIAM J. Appl. Dyn. Sy

Freezing of Gait in Parkinson’s Disease: A Perceptual Cuase for a Motor Impairment?

While freezing of gait (FOG) is typically considered a motor impairment, the fact that it occurs more frequently in confined spaces suggests that perception of space might contribute to FOG. The present study evaluated how doorway size influenced characteristics of gait that might be indicative of freezing. Changes in spatiotemporal aspects of gait were evaluated while walking through three different-sized doorways (narrow (0.675 m wide X 2.1 m high), normal (0.9 m wide X 2.1 m high) and wide (1.8 m wide X 2.1 m high)) in three separate groups: 15 individuals with Parkinson’s disease confirmed to be experiencing FOG at the time of test; 16 non-FOG individuals with Parkinson’s disease and 16 healthy age-matched control participants. Results for step length indicated that the FOG group was most affected by the narrow doorway and was the only group whose step length was dependent on upcoming doorway size as indicated by a significant interaction of group by condition (F(4,88)=2.73, p\u3c0.034). Importantly, the FOG group also displayed increased within-trial variability of step length and step time, which was exaggerated as doorway size decreased (F(4,88)=2.99, p\u3c0.023). A significant interaction between group and condition for base of support measures indicated that the non-FOG participants were also affected by doorway size (similar to Parkinson’s disease FOG) but only in the narrow doorway condition. These results support the notion that some occurrences of freezing may be the result of an underlying perceptual mechanism that interferes with online movement planning

Evaluating the Contributors of Dynamic Flow to Freezing Gait in Parkinson’s Disease

Although visual cues can improve gait in Parkinson’s disease (PD), their underlying mechanism is poorly understood. Previous research suggests that cues contribute optical flow that is essential to elicit gait improvement. The present study manipulated how optic flow was provided, and how this might influence freezing of gait (FOG) in PD. Therefore, three groups; 15 PD FOG, 16 PD non-FOG, and 16 healthy controls were tested in 3 narrow doorway conditions; baseline (Narrow), ground lines (Ground), and laser (Laser). Step length indicated that the PD FOG group was only able to improve with ground lines, while the laser increased gait variability and double support time. These results suggest that optic flow in itself is not enough to elicit gait improvement in PD. When PD patients use visual cues, gait becomes less automatically controlled and hence preplanned conscious control may be an important factor contributing to gait improvement

ABC implies primitive prime divisors in arithmetic dynamic

Let K be a number field, let f(x) in K(x) be a rational function of degree d> 1, and let z in K be a wandering point such that f^n(z) is nonzero for all n > 0. We prove that if the abc-conjecture holds for K, then for all but finitely many positive integers n, there is a prime p of K such that p | f^n(z) and p does not divide f^m(z) for all positive integers m < n. We prove the same result unconditionally for function fields of characteristic 0 when f is not isotrivial.Comment: 15 page

U.S. antidumping: much ado about zeroing

The United States use of"zeroing"in its antidumping procedures has become a political flash point threatening some legitimacy of the WTO's dispute settlement system. This paper provides a positive analysis of the zeroing issue, explains how it has evolved and who is likely to be affected by it. The authors use economic theory to identify how export price volatility accentuates the impact of zeroing on the size of U.S. antidumping tariffs and review the WTO caseload over zeroing. They describe the impact that the U.S.'s retrospective system for assessing antidumping margins has on zeroing and the political economy implications as the U.S. struggles to generate policy reform. The authors survey existing evidence of the impact of the zeroing on dumping margins and contribute their own evidence to suggest that zeroing is just as likely to impact the size of U.S. antidumping duties applied on developing country exportsas developed economy exports. Thus while developed economies have filed the vast majority of WTO disputes against the U.S. over zeroing, the authors conclude that zeroing is also likely a relevant issue for developing country exporters as over 60 percent of the product lines currently subject to U.S. antidumping are exported by developing countries.Markets and Market Access,Economic Theory&Research,Trade Law,Access to Markets,Emerging Markets

Instabilities and Patterns in Coupled Reaction-Diffusion Layers

We study instabilities and pattern formation in reaction-diffusion layers that are diffusively coupled. For two-layer systems of identical two-component reactions, we analyze the stability of homogeneous steady states by exploiting the block symmetric structure of the linear problem. There are eight possible primary bifurcation scenarios, including a Turing-Turing bifurcation that involves two disparate length scales whose ratio may be tuned via the inter-layer coupling. For systems of $n$-component layers and non-identical layers, the linear problem's block form allows approximate decomposition into lower-dimensional linear problems if the coupling is sufficiently weak. As an example, we apply these results to a two-layer Brusselator system. The competing length scales engineered within the linear problem are readily apparent in numerical simulations of the full system. Selecting a $\sqrt{2}$:1 length scale ratio produces an unusual steady square pattern.Comment: 13 pages, 5 figures, accepted for publication in Phys. Rev.