An Inverse Scattering Transform for the Lattice Potential KdV Equation

The lattice potential Korteweg-de Vries equation (LKdV) is a partial difference equation in two independent variables, which possesses many properties that are analogous to those of the celebrated Korteweg-de Vries equation. These include discrete soliton solutions, Backlund transformations and an associated linear problem, called a Lax pair, for which it provides the compatibility condition. In this paper, we solve the initial value problem for the LKdV equation through a discrete implementation of the inverse scattering transform method applied to the Lax pair. The initial value used for the LKdV equation is assumed to be real and decaying to zero as the absolute value of the discrete spatial variable approaches large values. An interesting feature of our approach is the solution of a discrete Gel'fand-Levitan equation. Moreover, we provide a complete characterization of reflectionless potentials and show that this leads to the Cauchy matrix form of N-soliton solutions

Comparing Wealth Effects: The Stock Market versus the Housing Market

We examine the link between increases in housing wealth, financial wealth, and consumer spending. We rely upon a panel of 14 countries observed annually for various periods during the past 25 years and a panel of U.S. states observed quarterly during the 1980s and 1990s. We impute the aggregate value of owner-occupied housing, the value of financial assets, and measures of aggregate consumption for each of the geographic units over time. We estimate regressions relating consumption to income and wealth measures, finding a statistically significant and rather large effect of housing wealth upon household consumption.Consumption, nonfinancial wealth, housing market, real estate

Comparing Wealth Effects: The Stock Market Versus the Housing Market

We examine the link between increases in housing wealth, financial wealth, and consumer spending. We rely upon a panel of 14 countries observed annually for various periods during the past 25 years and a panel of U.S. states observed quarterly during the 1980s and 1990s. We impute the aggregate value of owner-occupied housing, the value of financial assets, and measures of aggregate consumption for each of the geographic units over time. We estimate regressions relating consumption to income and wealth measures, finding a statistically significant and rather large effect of housing wealth upon household consumption.

Wealth Effects Revisited 1978-2009

We re-examine the link between changes in housing wealth, financial wealth, and consumer spending. We extend a panel of U.S. states observed quarterly during the seventeen-year period, 1982 through 1999, to the thirty-one year period, 1978 through 2009. Using techniques reported previously, we impute the aggregate value of owner-occupied housing, the value of financial assets, and measures of aggregate consumption for each of the geographic units over time. We estimate regression models in levels, first differences and in error-correction form, relating per capita consumption to per capita income and wealth. We find a statistically significant and rather large effect of housing wealth upon household consumption. This effect is consistently larger than the effect of stock market wealth upon consumption. This reinforces the conclusions reported in our previous analysis. In contrast to our previous analysis, however, we do find -- based on data which include the recent volatility in asset markets -- that the effects of declines in housing wealth in reducing consumption are at least as large as the effects of increases in housing wealth in increasing the course of household consumption.Consumption, Nonfinancial wealth, Housing market, Real estate

Renormalization group approach to 2D Coulomb interacting Dirac fermions with random gauge potential

We argue that massless Dirac particles in two spatial dimensions with $1/r$ Coulomb repulsion and quenched random gauge field are described by a manifold of fixed points which can be accessed perturbatively in disorder and interaction strength, thereby confirming and extending the results of arXiv:0707.4171. At small interaction and small randomness, there is an infra-red stable fixed curve which merges with the strongly interacting infra-red unstable line at a critical endpoint, along which the dynamical critical exponent $z=1$.Comment: 4 pages, 4 figure

The problem of mitotic recombination in Neurospora

The problem of mitotic recombination in Neurospor

GOPHER: A Computerized Cost/Benefit Analysis of Pocket Gopher Control

GOPHER is a computer program that can assist landowners, extension agents, and resource personnel in determining the cost-effectiveness of various methods of pocket gopher control. The program is interactive and user-friendly. It allows for the input of variables, including: crop type, acreage, expected yield and value, and acreage infested. Material and labor costs can be assigned or standard default values can be used. Other fixed variables can be changed, including: pocket gopher density and rate of increase, rate of treatment, rate of retreatment, and forage recovery rate. With these variables and values, GOPHER generates the costs, time, and economic feasibility of pocket gopher control. Control methods include: hand baiting, hand probe, gopher probe, burrow builder, and trapping. It also provides estimates of costs for second treatments and pocket gopher expansion without control. Free copies of GOPHER are available from the authors by providing formatted 5 1/4 inch floppy disks or 3 1/2 inch disks

A method for obtaining double mutants within single genes or gene clusters

Method for double mutants within genes or gene cluster

Stochastic evolution of four species in cyclic competition

We study the stochastic evolution of four species in cyclic competition in a well mixed environment. In systems composed of a finite number $N$ of particles these simple interaction rules result in a rich variety of extinction scenarios, from single species domination to coexistence between non-interacting species. Using exact results and numerical simulations we discuss the temporal evolution of the system for different values of $N$, for different values of the reaction rates, as well as for different initial conditions. As expected, the stochastic evolution is found to closely follow the mean-field result for large $N$, with notable deviations appearing in proximity of extinction events. Different ways of characterizing and predicting extinction events are discussed.Comment: 19 pages, 6 figures, submitted to J. Stat. Mec

Platinum promotion of Au/Al2O3 catalysts for glycerol oxidation: activity, selectivity and deactivation

Gold has been demonstrated as a possible catalyst for oxidation reactions. Some evidence for a possible promotion effect of platinum has also been recorded. The influence of platinum as promoter for Au/γ-Al2O3 prepared via anionic ion-exchange for the oxidation of glycerol was investigated in a batch reactor at 60°C. It is inferred that the addition of platinum reduces the catalytic activity and the rate of deactivation, resulting in an overall higher final conversion of glycerol with increasing platinum loading. The addition of platinum to the catalyst favours the formation of the desired product, glyceric acid