Who Lives on the Wrong Side of the Environmental Tracks? Evidence from the EPA's Risk-Screening Environmental Indicators Model

This study analyzes the social and economic correlates of air pollution exposure in U.S. cities using a unique dataset created as a by-product of the EPA’s Risk-Screening Environmental Indicators model and finds evidence of disproportionate exposure to environmental hazards in communities with higher concentrations of lower-income people and people of color. We improve on previous studies of environmental inequality in three ways. First, where previous studies focus on the proximity to point sources and the total mass of pollutants released, our measure of toxic exposure reflects atmospheric dispersion and chemical toxicity. Second, we analyze the data at a fine level of geographic resolution. Third, we control for substantial regional variations in pollution, allowing us to identify exposure differences both within cities and between cities. We combine 1998 data on toxicity-adjusted exposure to air pollution with 1990 Census block group data for urbanized areas. We find that blacks tend to live both in more polluted cities in the U.S. and in more polluted neighborhoods within cities. Hispanics live in less polluted cities on average, but they live in more polluted areas within cities. We find an extremely consistent income-pollution gradient, with lower income people significantly more exposed. Our findings highlight the importance of controlling for interregional variation in pollution levels in studies of the demographic correlates of pollution.

Variation in Organic Standards Prior to the National Organic Program

Interest in establishing nationally uniform certification, labeling, and management standards for organic products grew out of concern that the existence of multiple standards led to consumer and supply chain confusion about, and lack of confidence in, these products. The National Organic Program Final Rule, issued in December 2000, is the result of this interest. We analyze the certification system that was in place prior to the new national rule to evaluate the extent of differences between certification standards and how the national rule is likely to impact the market for organic products. Our analysis suggests that most differences among US certification standards were minor. Also, the most important impacts of the national standard may be in facilitating trade in ingredients and products certified by different certifiers, increasing buyer confidence, and facilitating exports. However, the national rule may decrease the ability of organic certifiers and consumers to place differing emphasis on the multiple goals of organic production and may decrease the flexibility of organic standards to respond to changing market conditions, including new technologies.organic agriculture, organic certification standards, organic labeling, organic market, Agribusiness, Marketing,

Market Power in Direct Marketing of Fresh Produce: Community Supported Agriculture Farms

CSA farms establish a loyal customer base and, potentially, market power. A new empirical industrial organization (NEIO) approach and survey data from Northeast CSA farms are used to determine whether CSA farms have market power and the extent to which they exercise their market power. Results suggest CSA farms exert about two percent of their potential monopoly power.Community Supported Agriculture; New Empirical Industrial Organization; Market Power; Fresh Produce; Organic Agriculture

Superfluidity in a Model of Massless Fermions Coupled to Scalar Bosons

We study superfluidity in a model of massless fermions coupled to a massive scalar field through a Yukawa interaction. Gap equations for a condensate with total spin J=0 are solved in the mean-field approximation. For the Yukawa interaction, the gaps for right- and left-handed fermions are equal in magnitude and opposite in sign, so that condensation occurs in the J^P = 0^+ channel. At finite scalar mass, there are two different gaps for fermions of a given chirality, corresponding to condensation of particle pairs or of antiparticle pairs. These gaps become degenerate in the limit of infinite scalar mass.Comment: 26 pages, 9 figures, RevTeX, epsf and psfig style files required. Revised version, discussion of the excitation spectrum extended, Fig. 2 adde

The excitation spectrum for weakly interacting bosons in a trap

We investigate the low-energy excitation spectrum of a Bose gas confined in a trap, with weak long-range repulsive interactions. In particular, we prove that the spectrum can be described in terms of the eigenvalues of an effective one-particle operator, as predicted by the Bogoliubov approximation.Comment: LaTeX, 32 page

Color superconductivity in weak coupling

We derive perturbatively the gap equations for a color-superconducting condensate with total spin J=0 in dense QCD. At zero temperature, we confirm the results of Son for the dependence of the condensate on the coupling constant, and compute the prefactor to leading logarithmic accuracy. At nonzero temperature, we find that to leading order in weak coupling, the temperature dependence of the condensate is identical to that in BCS-like theories. The condensates for total spin J=1 are classified; to leading logarithmic accuracy these condensates are of the same order as those of spin J=0.Comment: 30 pages, 3 figures, RevTeX, epsf and psfig style files require

Condensate fluctuations in finite Bose-Einstein condensates at finite temperature

A Langevin equation for the complex amplitude of a single-mode Bose-Einstein condensate is derived. The equation is first formulated phenomenologically, defining three transport parameters. It is then also derived microscopically. Expressions for the transport parameters in the form of Green-Kubo formulas are thereby derived and evaluated for simple trap geometries, a cubic box with cyclic boundary conditions and an isotropic parabolic trap. The number fluctuations in the condensate, their correlation time, and the temperature-dependent collapse-time of the order parameter as well as its phase-diffusion coefficient are calculated.Comment: 29 pages, Revtex, to appear in Phys.Rev.

A Green Function for Metric Perturbations due to Cosmological Density Fluctuations

We study scalar perturbations to a Robertson-Walker cosmological metric in terms of a pseudo-Newtonian potential, which emerges naturally from the solution of the field equations. This potential is given in terms of a Green function for matter density fluctuations of arbitrary amplitude whose time and spatial dependence are assumed known. The results obtained span both the linearized and Newtonian limits, and do not explicitly depend on any kind of averaging procedure, but make the valid assumption that the global expansion rate is that of a Friedmann-Robertson-Walker model. In addition, we discuss the similarity to diffusive processes in the evolution of the potential, and possible applications.Comment: 19 pages, REVTeX. SU-ITP-9233, submitted to Physical Review

Groundwater dynamics in coastal gravel barriers backed by freshwater lagoons and the potential for saline intrusion: Two cases from the UK

“NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Marine Systems. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Marine Systems, [VOL 123, (01.08.13)] DOI 10.1016/j.jmarsys.2013.04.004". The full text is under embargo until 01.08.15