Repairing a Mortgage Crisis: HOLC Lending and its Impact on Local Housing Markets

The Home Owners’ Loan Corporation purchased more than a million delinquent mortgages from private lenders between 1933 and 1936 and refinanced the loans for the borrowers. Its primary goal was to break the cycle of foreclosure, forced property sales and decreases in home values that was affecting local housing markets throughout the nation. We find that HOLC loans were targeted at local (county-level) housing markets that had experienced severe distress and that the intervention increased 1940 median home values and homeownership rates, but not new home building.

Filament tension and phase-locked drift of meandering scroll waves

Rotating scroll waves are self-organising patterns which are found in many oscillating or excitable systems. Here we show that quasi-periodic (meandering) scroll waves, which include the rotors that organise cardiac arrhythmias, exhibit filament tension when averaged over the meander cycle. With strong filament curvature or medium thickness gradients, however, scroll wave dynamics are governed by phase-locked drift instead of filament tension. Our results are validated in computational models of cycloidal meander and a cardiac tissue model with linear core.Comment: accepted for publication in Physical Review Letters (December 2017

Complex Patterns in Reaction-Diffusion Systems: A Tale of Two Front Instabilities

Two front instabilities in a reaction-diffusion system are shown to lead to the formation of complex patterns. The first is an instability to transverse modulations that drives the formation of labyrinthine patterns. The second is a Nonequilibrium Ising-Bloch (NIB) bifurcation that renders a stationary planar front unstable and gives rise to a pair of counterpropagating fronts. Near the NIB bifurcation the relation of the front velocity to curvature is highly nonlinear and transitions between counterpropagating fronts become feasible. Nonuniformly curved fronts may undergo local front transitions that nucleate spiral-vortex pairs. These nucleation events provide the ingredient needed to initiate spot splitting and spiral turbulence. Similar spatio-temporal processes have been observed recently in the ferrocyanide-iodate-sulfite reaction.Comment: Text: 14 pages compressed Postscript (90kb) Figures: 9 pages compressed Postscript (368kb

Noise Effects on the Complex Patterns of Abnormal Heartbeats

Patients at high risk for sudden death often exhibit complex heart rhythms in which abnormal heartbeats are interspersed with normal heartbeats. We analyze such a complex rhythm in a single patient over a 12-hour period and show that the rhythm can be described by a theoretical model consisting of two interacting oscillators with stochastic elements. By varying the magnitude of the noise, we show that for an intermediate level of noise, the model gives best agreement with key statistical features of the dynamics.Comment: 4 pages, 4 figures, RevTe

Mechanisms of Surviving Burial: Dune Grass Interspecific Differences Drive Resource Allocation After Sand Deposition

Sand dunes are important geomorphic formations of coastal ecosystems that are critical in protecting human populations that live in coastal areas. Dune formation is driven by ecomorphodynamic interactions between vegetation and sediment deposition. While there has been extensive research on responses of dune grasses to sand burial, there is a knowledge gap in understanding mechanisms of acclimation between similar, coexistent, dune-building grasses such as Ammophila breviligulata (C3), Spartina patens (C4), and Uniola paniculata (C4). Our goal was to determine how physiological mechanisms of acclimation to sand burial vary between species. We hypothesize that (1) in the presence of burial, resource allocation will be predicated on photosynthetic pathway and that we will be able to characterize the C3 species as a root allocator and the C4 species as leaf allocators. We also hypothesize that (2) despite similarities between these species in habitat, growth form, and life history, leaf, root, and whole plant traits will vary between species when burial is not present. Furthermore, when burial is present, the existing variability in physiological strategy will drive species-specific mechanisms of survival. In a greenhouse experiment, we exposed three dune grass species to different burial treatments: 0 cm (control) and a one-time 25-cm burial to mimic sediment deposition during a storm. At the conclusion of our study, we collected a suite of physiological and morphological functional traits. Results showed that Ammophila decreased allocation to aboveground biomass to maintain root biomass, preserving photosynthesis by allocating nitrogen (N) into light-exposed leaves. Conversely, Uniola and Spartina decreased allocation to belowground production to increase elongation and maintain aboveground biomass. Interestingly, we found that species were functionally distinct when burial was absent; however, all species became more similar when treated with burial. In the presence of burial, species utilized functional traits of rapid growth strategy, although mechanisms of change were interspecifically variable

The Effect of Smoking on Kentucky’s Workforce

Excerpt from the Executive Summary: Smoking has been estimated to increase health care costs in the United States by $167.5 billion annually (Xu et al. 2015). In Kentucky, smoking adds$2.5 billion in health care expenditures each year. Most of these costs were paid by public programs such as Medicaid and Medicare. While these costs are significant, they represent only a portion of the costs that smoking imposes on society. Smoking also leads to poorer labor market outcomes. Smokers are more likely to be unemployed, earn lower wages, and die prematurely than non-smokers. These negative labor market effects reduce economic activity and lower tax revenues, adding to the social costs and fiscal impact that smoking imposes. Past research shows that smokers generally earn four to eleven percent less than similar nonsmokers. Some of this wage penalty is due to the negative health consequences of smoking. Smoking can reduce workers’ health, causing them to be less productive, have higher health insurance costs, and incur greater rates of absenteeism. As a result, smokers tend to earn lower wages. However, the wage penalty might also reflect differences between those who decide to smoke and those who do not rather than being caused directly by smoking

The Economic Impact of Diabetes in Kentucky

Excerpt from the Executive Summary: The Kentucky Department of Public Health is responsible for improving the health and safety of Kentucky’s residents by preventing disease and injuries and encouraging healthy lifestyles. The department administers nearly 150 programs that address critical health issues affecting Kentuckians. These programs screen newborns for health problems, prevent the spread of infectious diseases, promote oral health, and provide numerous other services. Diabetes represents a growing health concern for the nation and Kentucky. It is a chronic condition that causes blood sugar levels to rise and contributes to other serious health conditions such as heart and kidney disease. The U.S. Centers for Disease Control and Prevention lists diabetes as the 7th leading cause of death in the nation. The disease imposes significant costs on the country’s economy. The American Diabetes Association estimates that the U.S. spends $237 billion annually on diabetes-related health care. In addition, diabetes also adversely affects the nation’s workforce. As the disease progresses, individuals may find it more difficult to work. This can reduce employment, productivity, wages, and tax revenue. To better understand how diabetes affects Kentucky residents, the Kentucky Department of Public Health contracted with the University of Kentucky’s Center for Business and Economic Research to study the economic impacts of the disease. This study has three main goals: estimate the effect diabetes has on Kentucky’s workforce; estimate the short-run and long-run effects diabetes has on state tax revenues; and examine how prevention and education programs could affect the health of those with diabetes and how they could potentially affect the state’s workforce and tax revenues

The Effects of Opioids on Kentucky\u27s Workforce

From the executive summary: Opioid abuse represents a significant and growing public health issue for both the nation and Kentucky. In 2016, opioids contributed to more than 62,000 deaths nationally and 1,406 deaths in Kentucky. National studies have placed the societal costs of opioid abuse at $55.7 billion in 2007 and$78.5 billion in 2013 (Birbaum et al. (2011) and Florence et al. (2016)). These costs included increased health care expenditures, higher criminal justice costs, and lost earnings due to reduced employment and premature deaths. The While House Council of Economic Advisors (2017) estimated the societal costs of opioid abuse to be much higher when the value of lives lost are included. They estimated the cost of opioid abuse to be $504 billion in 2015. Growth in opioid abuse creates fiscal pressures for state and local agencies by increasing the needs for foster care, health care, criminal justice programs, and many other types of public services. Because opioid abuse can also reduce employment and earnings, it adds to these fiscal pressures by reducing tax collections. To better understand these fiscal pressures, the Department of Public Health contracted with the University of Kentucky’s Center for Business and Economic Research (CBER) to study how opioid abuse affects the state’s workforce. This study has three main goals: estimate the effect opioid abuse has on Kentucky’s workforce; estimate the effect opioid abuse has on state tax revenues; and examine how public programs designed to address opioid abuse could affect the state’s workforce and tax revenues

Using the Memories of Multiscale Machines to Characterize Complex Systems

A scheme is presented to extract detailed dynamical signatures from successive measurements of complex systems. Relative entropy based time series tools are used to quantify the gain in predictive power of increasing past knowledge. By lossy compression, data is represented by increasingly coarsened symbolic strings. Each compression resolution is modeled by a machine: a finite memory transition matrix. Applying the relative entropy tools to each machine's memory exposes correlations within many time scales. Examples are given for cardiac arrhythmias and different heart conditions are distinguished.Comment: 4 pages, 2 figure

The Dynamics of Sustained Reentry in a Loop Model with Discrete Gap Junction Resistance

Dynamics of reentry are studied in a one dimensional loop of model cardiac cells with discrete intercellular gap junction resistance ($R$). Each cell is represented by a continuous cable with ionic current given by a modified Beeler-Reuter formulation. For $R$ below a limiting value, propagation is found to change from period-1 to quasi-periodic ($QP$) at a critical loop length ($L_{crit}$) that decreases with $R$. Quasi-periodic reentry exists from $L_{crit}$ to a minimum length ($L_{min}$) that is also shortening with $R$. The decrease of $L_{crit}(R)$ is not a simple scaling, but the bifurcation can still be predicted from the slope of the restitution curve giving the duration of the action potential as a function of the diastolic interval. However, the shape of the restitution curve changes with $R$.Comment: 6 pages, 7 figure