Teaching Bayesian Model Comparision with the Three-Sided Coin

In the present work we introduce the problem of determining the probability that a rotating and bouncing cylinder (i.e. flipped coin) will land and come to rest on its edge. We present this problem and analysis as a practical, nontrivial example to introduce the reader to Bayesian model comparison. Several models are presented, each of which take into consideration different physical aspects of the problem and the relative effects on the edge landing probability. The Bayesian formulation of model comparison is then used to compare the models and their predictive agreement with data from hand-flipped cylinders of several sizes

International Trade and the Environment: A Framework for Analysis

This paper sets out a general equilibrium pollution and trade model to provide a framework for examination of the trade and environment debate. The model contains as special cases a canonical pollution haven model as well as the standard Heckscher-Ohlin-Samuelson factor endowments model. We draw quite heavily from trade theory, but develop a simple pollution demand and supply system featuring marginal abatement cost and marginal damage schedules familiar to environmental economists. We have intentionally kept the model simple to facilitate extensions examining the environmental consequences of growth, the impact of trade liberalization, and strategic interaction between countries.

Trade, Tragedy, and the Commons

We develop a theory of resource management where the degree to which countries escape the tragedy of the commons is endogenously determined and explicitly linked to changes in world prices and other possible effects of market integration. We show how changes in world prices can move some countries from de facto open access situations to ones where management replicates that of an unconstrained social planner. Not all countries can follow this path of institutional reform and we identify key country characteristics (mortality rates, resource growth rates, technology) to divide the world's set of resource rich countries into Hardin, Ostrom and Clark economies. Hardin economies are not able to manage their renewable resources at any world price, have zero rents and suffer from the tragedy of the commons. Ostrom economies exhibit de facto open access and zero rents for low resource prices, but can maintain a limited form of resource management at higher prices. Clark economies can implement fully efficient management and do so when resource prices are sufficiently high. The model shows heterogeneity in the success of resource management is to be expected, and neutral technological progress works to undermine the efficacy of property rights institutions.

A Simple Model of Trade, Capital Mobility, and the Environment

This paper examines the interaction between relative factor abundance and income-induced policy differences in determining the pattern of trade and the effect of trade liberalization on pollution. If a rich and capital abundant North trades with a poor and labor abundant South, then free trade lowers world pollution. Trade shifts the production of pollution intensive industries to the capital abundant North despite its stricter pollution regulations. Pollution levels rise in the North while those in the South fall. These results can be reversed however if the North-South income gap is "too large," in this case, the pattern of trade is driven by income-induced pollution policy differences across countries. Capital mobility may raise or lower world pollution depending on the pattern of trade.

Free Trade and Global Warming: A Trade Theory View of the Kyoto Protocol

This paper demonstrates how three important results in environmental economics, true under mild conditions in closed economies, are false or need serious amendment in a world with international trade in goods. Since the three results we highlight have framed much of the ongoing discussion and research on the Kyoto protocol our viewpoint from trade theory suggests a re-examination may be in order. Specifically, we demonstrate that in an open trading world, but not in a closed economy setting: (1) unilateral emission reductions by the rich North can create self-interested emission reductions by the unconstrained poor South; (2) simple rules for allocating emission reductions across countries (such as uniform reductions) may well be efficient even if international trade in emission permits is not allowed; and (3) when international emission permit trade does occur it may make both participants in the trade worse off and increase global emissions.

Trade, Growth and the Environment

For the last ten years environmentalists and the trade policy community have engaged in a heated debate over the environmental consequences of liberalized trade. The debate was originally fueled by negotiations over the North American Free Trade Agreement and the Uruguay round of GATT negotiations, both of which occurred at a time when concerns over global warming, species extinction and industrial pollution were rising. Recently it has been intensified by the creation of the World Trade Organization (WTO) and proposals for future rounds of trade negotiations. The debate has often been unproductive. It has been hampered by the lack of a common language and also suffered from little recourse to economic theory and empirical evidence. The purpose of this essay is set out what we currently know about the environmental consequences of economic growth and international trade. We critically review both theory and empirical work to answer three basic questions. What do we know about the relationship between international trade, economic growth and the environment? How can this evidence help us evaluate ongoing policy debates? Where do we go from here?

Violaceous nodules in an HIV-positive man

Plasmablastic lymphoma (PBL) is a rare and aggressive malignancy associated with immunosuppression and the oncogenic effects of the Epstein-Barr virus (EBV). We present an HIV-positive man with PBL that presented as ulcers and violaceous exophytic nodules on the legs. The clinical features, histologic appearance, and differential diagnosis of this malignancy are briefly reviewed

Is Free Trade Good for the Environment?

This paper sets out a theory of how openness to international goods markets affects pollution concentrations. We develop a theoretical model to divide trade's impact on pollution into scale, technique, and composition effects and then examine this theory using data on sulfur dioxide concentrations when it alters the composition, and hence the pollution intensity, of national output. Our estimates of the associated technique and scale efforts created by trade imply a net reduction in pollution from these sources. Combining our estimates of scale, composition, and technique efforts yields a somewhat surprising conclusion: freer trade appears to be good for the environment.

A practice-led approach to facial animation research

In facial expression research, it is well established that certain emotional expressions are universally recognized. Studies into the observer perception of dynamic expressions have built upon this research by highlighting the importance of particular facial regions, timings, and temporal configurations to perception and interpretation. In many studies, the stimuli for such studies have been generated through posing by non-experts or performances by trained actors. However, skilled character animators are capable of crafting recognizable, believable emotional facial expressions as a part of their professional practice. ‘Emotional Avatars’ was conceived as an interdisciplinary research project which would draw upon the knowledge of animation practice and emotional psychology. The aim of the project was to jointly investigate the artistic generation and observer perception of emotional expression animation to determine whether the nuances of emotional facial expression could be artistically choreographed to enhance audience interpretation