Baryon Spectroscopy on the Lattice

Recent lattice QCD calculations of the baryon spectrum are outlined.Comment: Plenary contribution to Baryons 2002, Jefferson Lab, March 2002, 9 pages, 7 figure

Using information technology to help business students learn about contract law

This paper describes continuing work in using information technology (IT) to help Business students learn about contract law. The approach adopted uses a model of the contracting process as being one of negotiation, where the decisions made by the parties involve the acceptance or rejection of certain risks. Normal discussion tutorials are therefore replaced by a role‐play exercise in which students learn by taking part in simulated negotiations, each interested party being represented by a team of students. IT is being introduced into the learning process, both to provide decision‐support for the student teams, and to improve the mechanics of the exercise

Topology and chiral symmetry in finite temperature QCD

We investigate the realization of chiral symmetry in the vicinity of the deconfinement transition in quenched QCD using overlap fermions. Via the index theorem obeyed by the overlap fermions, we gain insight into the behavior of topology at finite temperature. We find small eigenvalues, clearly separated from the bulk of the eigenvalues, and study the properties of their distribution. We compare the distribution with a model of a dilute gas of instantons and anti-instantons and find good agreement.Comment: 3 pages with 3 ps figures; to appear in the proceedings of Lattice '99, Pisa, Italy, June 29 -- July 3, 1999. LATTICE99(topology

US Trade and Wages: The Misleading Implications of Conventional Trade Theory

Conventional trade theory, which combines the Heckscher-Ohlin theory and the Stolper- Samuelson theorem, implies that expanded trade between developed and developing countries will increase wage equality in the former. This theory is widely applied. It serves as the basis for estimating the impact of trade on wages using two-sector simulation models and the net factor content of trade. It leads naturally to the presumption that the rapid growth and declining relative prices of US manufactured imports from developing countries since the 1990s have been a powerful source of increased US wage inequality. In this study we present evidence that suggests the presumption is not warranted. We highlight the sensitivity of conventional theory to the assumption of incomplete specialization and find evidence that is not consistent with it. Since 1987, although US domestic relative effective prices in industries with relatively high shares of manufactured goods imports from developing countries have declined, effective unskilled-worker weighted prices have actually risen relative to skilled- worker-weighted prices. If anything this suggests pressures for increased wage equality. Also in apparent contradiction to theory, the (six-digit NAICS) US manufacturing industries with high shares of manufactured imports from developing countries are actually more skill-intensive than the industries with high shares of imports from developed countries. Finally, applying a two-stage regression procedure, we find that developing country import price changes have not mandated increased US wage equality. While these results conflict with standard theory, they are easily explained if the US and developing countries have specialized in products and tasks that are imperfect substitutes. If this is the case, the impact of increased trade with developing countries on US wage inequality is far more muted than standard theory suggests. Also methodologies such as the net factor content of trade using US production coefficients and simulation models assuming perfect substitution between imports and domestic products could be highly misleading.

ECONOMIC AND SOCIAL INDICATORS OF RURAL DEVELOPMENT FROM AN ECONOMIC VIEWPOINT

Community/Rural/Urban Development,

Changes in fish populations in the Lower Canyons of the Rio Grande

The Lower Canyons of the Rio Grande suffer from environmental degradation that has negatively impacted native fish populations and their distributions. Macrhybopsis aestivalis (speckled chub), Notropis jemezanus (Rio Grande shiner), Rhinichthys cataractae (longnose dace) and Cycleptus elongatus (blue sucker) populations appear to have suffered recent declines. Although diminished water quantity is likely an important factor in these declines, related changes in channel morphology precipitated by massive stands of Arundo donax (giant reed) and Tamarix sp. (salt cedar) may also be responsible. These invasive exotics have essentially channelized the river, disrupted normal sediment distribution and reduced shallow, low-velocity habitats. Much of the Lower Canyons of the Rio Grande are devoid of sandy sediment and most riffles are now composed of gravel and cobble.Integrative Biolog

Temporal Changes in the Fishes of Waller Creek and Invasion of the Variable Platyfish

This poster was presented at the second Waller Creek Symposium held on the University of Texas campus at the Recreational Sports Center on May 7, 2018.Waller Creek is an entirely urban creek flowing 11km through Austin, Travis County, Texas into Ladybird Lake. We gather the historic fish data, all held in our own Fishes of Texas Project database (Hendrickson and Cohen, 2018), for the creek and attempt to describe temporal change in the fauna of the creek. Minimal samples exist from the 1940’s and ’50s, but its fish fauna is rigorously sampled in the 1970’s when Edwards (1976) first formally surveyed the creek. It was uncollected in the 1980s. The Hendrickson lab, working with the public, local schools and universities, began sampling the creek in the 1990’s and continues to do so. These two sources (Edwards and Hendrickson Lab) are the main generators of data and we compared pre- and post-1980s data largely generated by these two sources. The fish fauna remains dominated by the same seven species Edwards collected in the 1970s (Gambusia affinis, Campostoma anomalum, Astyanax mexicanus, Lepomis megalotis, Lepomis cyanellus, Cyprinella lutrensis, and Herichthys cyanoguttatus), with the exception of an invasive species (Xiphophorus variatus), first detected in 2004, that is now the dominant species in the creek. Two of these seven species are firmly established non-natives (Astyanax mexicanus and Herichthys cyanoguttatus). Most of the less common native species collected in the 1970’s are no longer present (Ameiurus melas, Dionda flavipinnis, Fundulus zebrinus, Lepomis humilis, Lepomis macrochirus) or rare (Cyprinella venusta, Micropterus salmoides, Pimephales promelas) based on the data.Integrative BiologyWaller Creek Working Grou

Two Photon Decays of Charmonia from Lattice QCD

We make the first calculation in lattice QCD of two-photon decays of mesons. Working in the charmonium sector, using the LSZ reduction to relate a photon to a sum of hadronic vector eigenstates, we compute form-factors in both the space-like and time-like domains for the transitions $\eta_c \to \gamma^* \gamma^*$ and $\chi_{c0} \to \gamma^* \gamma^*$. At the on-shell point we find approximate agreement with experimental world-average values.Comment: Replaced with version to be published in PRL. Expanded discussion of possible systematic error