Does Housing Wealth Make Us Less Equal? The Role of Durable Goods in the Distribution of Wealth

We study the role an illiquid durable consumption good plays in determining the level of precautionary savings and the distribution of wealth in a standard Aiyagari model (i.e. a model with heterogeneous agents, idiosyncratic uncertainty, and borrowing constraints). Transactions costs induce an inaction region over which the durable stock and the associated user cost are not adjusted in response to changes in income, increasing, on average, the volatility of non-durable consumption. The volatility of total consumption is then a function of the share of the durable good in the utility function and the width of the inaction region. We are particularly interested in parameterizations which increase the precautionary motive for saving through an increase in "committed expenditure risk". We find, for an empirically relevant share of durable consumption and for all transaction costs below an upper threshold, that the level of precautionary savings is increasing in the transaction costs. Transaction costs have only a modest impact on the degree of wealth dispersion, as measured by the Gini index, as the associated increase in savings is close to linear in wealth. While we are unable to match the dispersion of wealth in the data, we increase the dispersion over a single asset model (Gini index of .71 for financial assets and .37 for total wealth) and we are able to match the relative dispersion of financial to durable assets, i.e. we find financial assets much more unequal than durable assets. We also match the ratio of housing wealth to total wealth for the median agent. We calibrate the model to data from the PSID, the CES, and the SCFPrecautionary Savings, Wealth Distribution, Durable Goods

Self-noise produced by an airfoil with nonflat plate trailing-edge serrations

This paper represents the results of an experimental study aimed at reducing the airfoil self-noise by the trailing edge serration of four different sawtooth geometries (defined in the serration angle and length). These serrations have a common feature: all of the sawtooth patterns are cut directly into the trailing edge of a realistic airfoil. This configuration offers better structural strength and integrity. For the sawtooth trailing edges investigated here, the radiation of the extraneous vortex shedding noise in a narrowband frequency due to the partial bluntness at the serration roots is unavoidable. However, this narrowband component tends to be less significant provided that the serration angle is large and the serration length is moderate. Sound power was measured, and some of the sawtooth geometries have been shown to afford significant boundary-layer instability tonal noise and moderate turbulent broadband noise reductions across a fairly large velocity range. This paper demonstrates that a nonflat plate serrated trailing edge can also be effective in the self-noise reduction. Some experimental results are also presented in order to explain the self-noise mechanisms.This work is partly supported by the Brunel Research Initiative and Enterprise fun

Nursing Home Quality as a Public Good

There has been much debate among economists about whether nursing home quality is a public good across Medicaid and private-pay patients within a common facility. However, there has been only limited empirical work addressing this issue. Using a unique individual level panel of residents of nursing homes from seven states, we exploit both within-facility and within-patient variation in payer source and quality to examine this issue. We also test the robustness of these results across states with different Medicaid and private-pay rate differentials. Across our various identification strategies, the results generally support the idea that quality is a public good within nursing homes. That is, within a common nursing home, there is very little evidence to suggest that Medicaid-funded residents receive consistently lower quality care relative to their private-paying counterparts.

RUNNING INJURIES: FOREFOOT VERSUS REARFOOT AND BAREFOOT VERSUS SHOD: A BIOMECHANIST’S PERSPECTIVE

In recent years, there has been a debate regarding the use of different footfall patterns to reduce injury risk and enhance performance. Humans have three footfall patterns available to them when running: rearfoot, midfoot and forefoot. These different patterns are distinguished by the portion of the foot that’s makes initial contact with the ground. Interestingly, until very recently, there has been little research to show the pros or cons of the various footfall patterns. Here we will discuss several studies that have been carried out to distinguish footfall patterns in terms of kinematics and kinetics, running economy, the effect of surface and coordination on the risk of running injury

Perspective: tobacco manufacturers are now compensating states for smoking-related costs: how will this affect the economy?

Smoking out the social and economic benefits of the 1998 tobacco settlement for Massachusetts.Tobacco industry ; Medical care, Cost of

A Bayesian method for assessing multi-scale species-habitat relationships

Context Scientists face several theoretical and methodological challenges in appropriately describing fundamental wildlife-habitat relationships in models. The spatial scales of habitat relationships are often unknown, and are expected to follow a multi-scale hierarchy. Typical frequentist or information theoretic approaches often suffer under collinearity in multiscale studies, fail to converge when models are complex or represent an intractable computational burden when candidate model sets are large. Objectives Our objective was to implement an automated, Bayesian method for inference on the spatial scales of habitat variables that best predict animal abundance. Methods We introduce Bayesian latent indicator scale selection (BLISS), a Bayesian method to select spatial scales of predictors using latent scale indicator variables that are estimated with reversible-jump Markov chain Monte Carlo sampling. BLISS does not suffer from collinearity, and substantially reduces computation time of studies. We present a simulation study to validate our method and apply our method to a case-study of land cover predictors for ring-necked pheasant (Phasianus colchicus) abundance in Nebraska, USA. Results Our method returns accurate descriptions of the explanatory power of multiple spatial scales, and unbiased and precise parameter estimates under commonly encountered data limitations including spatial scale autocorrelation, effect size, and sample size. BLISS outperforms commonly used model selection methods including stepwise and AIC, and reduces runtime by 90%. Conclusions Given the pervasiveness of scale-dependency in ecology, and the implications of mismatches between the scales of analyses and ecological processes, identifying the spatial scales over which species are integrating habitat information is an important step in understanding species-habitat relationships. BLISS is a widely applicable method for identifying important spatial scales, propagating scale uncertainty, and testing hypotheses of scaling relationships

Reliability and effect of partially restrained wood shear walls

ABSTRACT RELIABILITY AND EFFECT OF PARTIALLY RESTRAINED WOOD SHEAR WALLS by JOHN J. GRUBER MARCH 2012 Advisor: Dr. Gongkang Fu Major: Civil Engineering Degree: Doctor or Philosophy The prescriptive design of the most widely used residential building code in the United States, the IRC, allows the use of partially restrained wood shear walls to resist wind and seismic loads. Wind load is the most common controlling lateral design load for these structures. In contrast, the complimenting building code, the IBC, requires either a restraining dead load or a mechanical hold down device to resist overturning. To prescribe a safe structure, it is important to know the effect of partial restraint on the overturning resistance of wood shear walls constructed in accordance with the IRC and equally important whether the partially restrained wood shear walls provide the same level of reliability as fully restrained wood shear walls for wind load. This is the focus of this research. Twenty five Monotonic tests were conducted of 4\u27 x 8\u27 wood shear walls with five varying restraining methods (wall types). There were five sets of five wall types. One of the sets had only an anchor bolt, three sets had different dead loads with one anchor bolt, and one set had a mechanical hold down. The results of the test program were used to determine the partial restraint effect, create a nonlinear finite element model, and to determine the statistical data required to perform a Monte Carlo simulation of the wall behavior. The Monte Carlo simulation result was used to calibrate a nonlinear partial restraint factor to a target reliability index of 3.25. The calibration was performed for both ASD and LRFD load combinations as required by the IBC. The research concludes with a closed-form solution, including the calibrated nonlinear partial restraint factor developed, to determine the unit shear capacity of a partially restrained or fully restrained (with dead load or mechanical hold down) wood shear wall constructed in accordance with the IRC by utilizing the fully restrained nominal unit shear values of AF&PA\u27s Special Design Provisions for Wind and Seismic

Estimating the Use of Public Lands: Integrated Modeling of Open Populations with Convolution Likelihood Ecological Abundance Regression

We present an integrated open population model where the population dynamics are defined by a differential equation, and the related statistical model utilizes a Poisson binomial convolution likelihood. Key advantages of the proposed approach over existing open population models include the flexibility to predict related, but unobserved quantities such as total immigration or emigration over a specified time period, and more computationally efficient posterior simulation by elimination of the need to explicitly simulate latent immigration and emigration. The viability of the proposed method is shown in an in-depth analysis of outdoor recreation participation on public lands, where the surveyed populations changed rapidly and demographic population closure cannot be assumed even within a single day