Airports, Air Pollution, and Contemporaneous Health

Airports are some of the largest sources of air pollution in the United States. We demonstrate that daily airport runway congestion contributes significantly to local pollution levels and contemporaneous health of residents living nearby and downwind from airports. Our research design exploits the fact that network delays originating from large airports on the East Coast increase runway congestion in California, which in turn increases daily pollution levels around California airports. Using the component of California air pollution driven by airport congestion, we find that carbon monoxide (CO) leads to significant increases in hospitalization rates for asthma, respiratory, and heart related emergency room admissions that are an order of magnitude larger than conventional estimates: A one standard deviation increase in daily pollution levels leads to an additional $1 million in hospitalization costs for respiratory and heart related admissions for the 6 million individuals living within 10km (6.2 miles) of the 12 largest airports in California. While infants and the elderly are more sensitive to air pollution, we also find significant relationships for the adult population. The health impacts are driven by CO, not NO2 or O3, and occur at levels far below existing EPA mandates. Our results suggest there may be sizable morbidity benefits from lowering the existing CO standard.

The economic impacts of climate change: Evidence from agricultural output and random fluctuations in weather: Comment

In a series of studies employing a variety of approaches, we have found that the potential impact of climate change on US agriculture is likely negative. Deschênes and Greenstone (2007) report dramatically different results based on regressions of agricultural profits and yields on weather variables. The divergence is explained by (1) missing and incorrect weather and climate data in their study; (2) their use of older climate change projections rather than the more recent and less optimistic projections from the Fourth Assessment Report; and (3) difficulties in their profit measure due to the confounding effects of storage

A variational principle for cyclic polygons with prescribed edge lengths

We provide a new proof of the elementary geometric theorem on the existence and uniqueness of cyclic polygons with prescribed side lengths. The proof is based on a variational principle involving the central angles of the polygon as variables. The uniqueness follows from the concavity of the target function. The existence proof relies on a fundamental inequality of information theory. We also provide proofs for the corresponding theorems of spherical and hyperbolic geometry (and, as a byproduct, in $1+1$ spacetime). The spherical theorem is reduced to the euclidean one. The proof of the hyperbolic theorem treats three cases separately: Only the case of polygons inscribed in compact circles can be reduced to the euclidean theorem. For the other two cases, polygons inscribed in horocycles and hypercycles, we provide separate arguments. The hypercycle case also proves the theorem for "cyclic" polygons in $1+1$ spacetime.Comment: 18 pages, 6 figures. v2: typos corrected, final versio

New Luttinger liquid physics from photoemission on Li0.9_{0.9}Mo6_6O17_{17}

Temperature dependent high resolution photoemission spectra of quasi-1 dimensional Li$_{0.9}$Mo$_6$O$_{17}$ evince a strong renormalization of its Luttinger liquid density-of-states anomalous exponent. We trace this new effect to interacting charge neutral critical modes that emerge naturally from the two-band nature of the material. Li$_{0.9}$Mo$_6$O$_{17}$ is shown thereby to be a paradigm material that is capable of revealing new Luttinger physics.Comment: 4 pages, 3 figures. Accepted for publication by Phys. Rev. Let

Long-Term Trends in Gas-Particle Partitioning of Reduced Reactive Nitrogen Species, as Analyzed by Annular Denuders and Ion Chromatography

Reduced reactive nitrogen species, which primarily consist of ammonia and low-mass amines, occur in the gas-phase and the particle-phase of the atmosphere. Despite being present at trace concentrations, these species can have severe effects on eutrophication, biodiversity, human pulmonary and cardiac health, and deposition. Long-term sampling of these species is infrequent, and such sampling that has taken place is focused around agricultural sources rather than urban environments. A greater understanding of the gas-particle partitioning of these species elucidates our understanding of the roles they play in the aforementioned environmental effects.&nbsp; I adapted the EPA&rsquo;s procedure for the sampling of ambient air using annular denuders and performed troubleshooting techniques on an ion chromatograph to develop a method to collect and analyze reduced nitrogen species; with this method, phases can be examined separately, thus allowing for a greater understanding of the magnitude of each risk associated with the gas and particle-phases rather than conflating the total concentration together. Method development is a crucial step in initiating long-term sampling, because consistency is the foundation of accuracy. I began preliminary ambient sampling with a focus on ensuring the procedure works and exploring potential trends.&nbsp; &nbsp; While further sampling over the course of years will be necessary to confirm trends, some trends are beginning to emerge: gas-phase ammonia is present in higher concentrations when the average temperature is greater. The total concentration and the ratio of gas-to-particle concentrations are still being considered, as are these apparent trends. For the future, focus should be directed towards identifying the dominant source of analyte in the second annular denuder, observing effects of different filters, refining the gradient method, and considering the maximum collectable concentration on the denuders and filter. </p

Luttinger liquid ARPES spectra from samples of Li0.9_{0.9}Mo6_6O17_{17} grown by the temperature gradient flux technique

Angle resolved photoemission spectroscopy line shapes measured for quasi-one-dimensional Li$_{0.9}$Mo$_6$O$_{17}$ samples grown by a temperature gradient flux technique are found to show Luttinger liquid behavior, consistent with all previous data by us and other workers obtained from samples grown by the electrolyte reduction technique. This result eliminates the sample growth method as a possible origin of considerable differences in photoemission data reported in previous studies of Li$_{0.9}$Mo$_6$O$_{17}$.Comment: Some text adde

Non-Fermi liquid angle resolved photoemission lineshapes of Li0.9Mo6O17

A recent letter by Xue et al. (PRL v.83, 1235 ('99)) reports a Fermi-Liquid (FL) angle resolved photoemission (ARPES) lineshape for quasi one-dimensional Li0.9Mo6O17, contradicting our report (PRL v.82, 2540 ('99)) of a non-FL lineshape in this material. Xue et al. attributed the difference to the improved angle resolution. In this comment, we point out that this reasoning is flawed. Rather, we find that their data have fundamental differences from other ARPES results and also band theory.Comment: To be published as a PRL Commen

Non-fermi-liquid single particle lineshape of the quasi-one-dimensional non-CDW metal Li_{0.9}Mo_{6}O_{17} : comparison to the Luttinger liquid

We report the detailed non-Fermi liquid (NFL) lineshape of the dispersing excitation which defines the Fermi surface (FS) for quasi-one-dimensional Li_{0.9}Mo_{6}O_{17}. The properties of Li_{0.9}Mo_{6}O_{17} strongly suggest that the NFL behavior has a purely electronic origin. Relative to the theoretical Luttinger liquid lineshape, we identify significant similarities, but also important differences.Comment: 5 pages, 3 eps figure