A variational perturbation scheme for many-particle systems in the functional integral approach

A variational Perturbation theory based on the functional integral approach is formulated for many-particle systems. Using the variational action obtained through Jensen-Peierls' inequality, a perturbative expansion scheme for the thermodynamic potential is established. A modified Wick's theorem is obtained for the variational perturbation expansions. This theorem allows one to carry out systematic calculations of higher order terms without worrying about the double counting problem. A model numerical calculation was carried out on a nucleon gas system interacting through the Yukawa-type potential to test the efficiency of the present method.Comment: accepted for publication in Phys. Rev.

Impacts of Regulating Greenhouse Gas Emissions on Livestock Trade Flows

The policies that regulate greenhouse gas emissions would provide a significant burden to emission industries as well as final consumers, which can lead to a strong influence on international trade flows of commodities. This study examines the impact of regulating greenhouse gas emissions on livestock trade flows using a commodity specific gravity model approach. This study finds that regulating greenhouse gas emissions has a negative effect on livestock trade flows from countries restricting greenhouse gas emissions to unrestricting countries, from restricting to restricting countries, and from unrestricting to restricting countries.gravity model, livestock, regulating greenhouse gas emission, trade, Environmental Economics and Policy, Livestock Production/Industries,

ANALYSIS OF U.S. WHEAT MARKET SHARES IN EAST ASIA

The effects of U.S. wheat prices, dollar values, and their volatilities on U.S. wheat market shares in 10 Asian countries are analyzed. The variables are converted to a relative form comparing the U.S. against Australian and Canadian variables in order to incorporate the effects of competition among these countries. The effects of the increased loan rates and target prices in the early 1980s and the U.S. export enhancement program (EEP) are also analyzed. Estimation results show that higher U.S. wheat prices and U.S. dollar appreciation have detrimental effects, while increases in competitors? wheat prices and currency values have cross positive effects on U.S. market shares. The importers are not sensitive to volatility in annual price and exchange rate changes. Dummy variables representing the domestic farm and trade policies are not statistically significant, implying that the two variables do not have a substantial effect on U.S. wheat export performance in the markets.international wheat trade, market share, panel unit-root test, panel estimation, Crop Production/Industries, International Relations/Trade,

THE EFFECT OF FOOD-SAFETY RELATED INFORMATION ON CONSUMERS' PREFERENCE: THE CASE OF BSE OUTBREAK IN JAPAN

This study analyzes consumers' responses to food-safety related information by evaluating if Japanese consumers have undergone a structural change in their preferences for meat due to the BSE outbreak in the country. The axiom of revealed preference is utilized to test the stability of preference in Japanese meat consumption. The matrix of weak form of revealed preference (WARP) is partitioned and Kruskal-Wallis statistics are derived to evaluate whether the switches of preference are transitory or due to a structural change. Empirical results show that Japanese meat demand has undergone a structural change, synchronized with the BSE outbreak in Japan in mid-September 2001.Food Consumption/Nutrition/Food Safety,

U.S. MEAT EXPORTS AND FOOD SAFETY INFORMATION

New information about food safety can stimulate a sudden, significant concern by the public, resulting in a pronounced change in consumer demand. One such example is the declining level of beef consumption in Europe and Japan, stemming from the outbreak of Bovine Spongiform Encephalopathy (BSE), known as mad-cow disease. This study evaluates the impacts of the BSE outbreak in Japan in September 2001 on the import demands for U.S. meat in Japan and South Korea, using a nonparametric revealed preference approach. Empirical results show that there are excess violations in the Japanese data after the timing of the outbreak, but not in the South Korean data, implying that the event has influenced Japanese meat import demand, but not South Korean meat import demand.Bovine Spongiform Encephalopathy, meat import demand, revealed preference, Food Consumption/Nutrition/Food Safety, International Relations/Trade,