The photosensitized generation of reactive oxygen species, and particularly of singlet oxygen [O2 (a(1) Δg )], is the essence of photodynamic action exploited in photodynamic therapy. The ability to switch singlet oxygen generation on/off would be highly valuable, especially when it is linked to a cancer-related cellular parameter. Building on recent findings related to intersystem crossing efficiency, we designed a dimeric BODIPY dye with reduced symmetry, which is ineffective as a photosensitizer unless it is activated by a reaction with intracellular glutathione (GSH). The reaction alters the properties of both the ground and excited states, consequently enabling the efficient generation of singlet oxygen. Remarkably, the designed photosensitizer can discriminate between different concentrations of GSH in normal and cancer cells and thus remains inefficient as a photosensitizer inside a normal cell while being transformed into a lethal singlet oxygen source in cancer cells. This is the first demonstration of such a difference in the intracellular activity of a photosensitizer.

This paper develops an econometric model of stochastic production functions to quantify the impacts of climatic variables on the mean, variance, and covariance of crop yields. The estimates of the production function parameters and their elasticities are utilized to analyse the impacts of the projected climate change on agriculture. The results show that the climate change will have modest effects on the mean crop yields, but will significantly reduce the variance and covariance for most of the crops considered. The results have implications for allocations of agricultural land among crops and for crop production mix.

A model of farmer decision making is developed to determine the extent to which uncertainties about soil fertility and weather affect the value of site‐specific technologies (SSTs) using jointly estimated risk and technology parameters. Uncertainty can lead risk‐averse farmers to apply more fertilizers and generate more pollution than in the certainty case. Ignoring uncertainty and risk aversion would overestimate the economic and environmental benefits of SSTs and underestimate the subsidy required to induce adoption. Accounting for uncertainties and risk preferences might explain the low observed adoption rates of SSTs. Improving the accuracy of SSTs would increase the incentives for adoption.

Substantial public scrutiny about adverse environmental impacts of the dairy sector has resulted in increased environmental regulations. A behavioral model of location and production is developed to examine the impacts of environmental regulations, traditional location factors, and agglomeration economies on the spatial structure and geographical location of dairy production. The results show that counties in the states with more stringent environmental regulations tend to lose dairy inventories to those with less stringent policies. There are substantially meaningful spatial patterns of dairy production. Current dairy production levels are positively correlated while changes in production levels are negatively correlated across counties. Copyright 2004, Oxford University Press.