Deformation Quantization of the Isotropic Rotator

We perform a deformation quantization of the classical isotropic rigid rotator. The resulting quantum system is not invariant under the usual $SU(2)\times SU(2)$ chiral symmetry, but instead $SU_{q^{-1}}(2) \times SU_q(2)$.Comment: 12pp, LATE

Two-parameter deformation of the Poincar\'e algebra

We examine a two-parameter ($\hbar ,$ $\lambda$) deformation of the Poincar\`e algebra which is covariant under the action of $SL_q(2,C).$ When $\lambda \rightarrow 0$ it yields the Poincar\`e algebra, while in the $\hbar\rightarrow 0$ limit we recover the classical quadratic algebra discussed previously in \cite{ssy95}, \cite{sy95}. The analogues of the Pauli-Lubanski vector $w$ and Casimirs $p^2$ and $w^2$ are found and a set of mutually commuting operators is constructed.Comment: 10 pages, Latex2

The Rise and Fall of the Environmental Kuznets Curve

This paper chronicles the story of the environmental Kuznets curve (EKC). The EKC proposes that indicators of environmental degradation first rise, and then fall with increasing income per capita. However, recent evidence shows that developing countries are addressing environmental issues, sometimes adopting developed country standards with a short time lag and sometimes performing better than some wealthy countries, and that the EKC results have a very flimsy statistical foundation. A new generation of decomposition models can help disentangle the true relations between development and the environment.

Reversal in the Trend of Global Anthropogenic Sulfur Emissions

Global anthropogenic sulfur emissions increased until the late 1980s. Existing estimates for 1995 and 2000 show a moderate decline from 1990 to 1995 or relative stability throughout the decade. This paper combines previously published data and new econometric estimates to show a 25% decline over the decade to a level not seen since the early 1960s. The decline is evident in North America, Western and Eastern Europe and in the last few years in East and South Asia. If this new trend is maintained local air pollution problems will be ameliorated but global warming may be somewhat exacerbated.

Global Sulfur Emissions in the 1990s

This paper provides global and individual country estimates of sulfur emissions from 1991-2000. Raw estimates are obtained in two ways. For countries and years with published data I compile that data from the available sources. For the remaining countries and for missing years for countries with some published data, I use either the decomposition model estimated by Stern (2002), the first differences environmental Kuznets curve model estimated by Stern and Common (2001), or a simple extrapolation, depending on the availability of data to interpolate or extrapolate estimates. The results are combined with estimates from the ASL database for earlier years to develop continuous time series from 1850 to 2000. Finally, I discuss the main movements in global and regional emissions in the 1990s and compare the results to other studies. Global emissions peaked in 1989 or 1991 and declined rapidly thereafter. The locus of emissions shifted towards East and South Asia, but even this region peaked in 1996. Our estimates tend to be lower than other published studies and show a much more rapid decline reflecting the view that technological progress in reducing sulfur based pollution has been rapid and is beginning to diffuse worldwide.

Derivation of the Hicks Elasticity of Substitution from the Input Distance Function

The Hicks or direct elasticity of substitution is traditionally derived from the production function. This paper exploits duality theory to present a more general derivation from the input distance function, which is exactly dual to the Shadow Elasticity of Substitution. The new elasticity is more general than the traditional one as it can handle situations of technical inefficiency, nonseparability between inputs and outputs, and multiple outputs, but is equal to the traditional elasticity under the classical conditions. The new derivation is related to the Morishima and Antonelli Elasticities of Complementarity in the same way that the Shadow Elasticity of Substitution is related to the Morishima and Allen-Uzawa Elasticities of Substitution. Furthermore, distance (technical efficiency) is not constant for the Morishima and Antonelli Elasticities of ComplementarityMicroeconomics; production; substitution

Global sulfur emissions in the 1990s

This paper provides global and country by country estimates of sulfur emissions for the early and mid-1990s. Raw estimates are obtained in two ways. For countries with published data we compile that data from the available sources. For the remaining countries, we use either the decomposition model estimated by Stern (1999), the first differences environmental Kuznets curve model estimated by Stern and Common (2001), or simple extrapolation depending on the availability of data on the explanatory variables. We then examine the compatibility of these estimates with the ASL estimates for 1990. Based on these and other comparisons we construct a preferred database for 1850-1999 and discuss the main movements in the 1990s. The data is available from the datasite.

Diffusion of Emissions Abating Technology

The environmental Kuznets curve (EKC) has been extensively criticized on econometric and theoretical grounds. Recent econometric results and case studies show that national emissions of important pollutants are monotonic in income but changes in technology can lead over time to reductions in pollution - a lowering of the EKC - and that pollution reducing innovations and standards may be adopted with relatively short time lags in some developing countries. This study combines the recent literature on measuring environmental efficiency and technological change using production frontier methods with the use of the Kalman filter - a time series method for signal extraction - to model the state of abatement technology in a panel of countries over time. The EKC is reformulated as the best practice technology frontier - countries' position relative to the frontier reflects the degree to which they have adopted best practice. The results are used to determine whether countries are converging to best practice over time and how many years it will take each country to achieve current best practice. The model is applied to sulfur dioxide emissions from sixteen mainly developed countries.

Energy quality

This paper develops economic definitions of energy quality for individual fuels and energy aggregates. There are both use- and exchange-value concepts as well as marginal and total measures of energy quality. A factor augmentation or quality coefficients approach corresponds to the use-value definition while indicators based on distance functions and relative prices are exchange-value based definitions. These indicators are identical when the elasticity of substitution between fuels is infinity but diverge or cannot be computed for other interfuel elasticities of substitution. Under zero substitutability only the quality coefficients approach is defined. I also find that the ratio of an energy volume index to aggregate joules cannot be considered a complete indicator of aggregate energy quality as it does not account for quality changes in the component fuels.Energy; Quality; Productivity