Timing and Tempo of Early and Successive Adaptive Radiations in Macaronesia

The flora of Macaronesia, which encompasses five Atlantic archipelagos (Azores, Canaries, Madeira, Cape Verde, and Salvage), is exceptionally rich and diverse

Past Arctic aliens have passed away, current ones may stay

Published version. Source at http://doi.org/10.1007/s10530-015-0937-9.Increased human activity and climate change are expected to increase the numbers and impact of alien species in the Arctic, but knowledge of alien species is poor in most Arctic regions. Through field investigations over the last 10 years, and review of alien vascular plant records for the high Arctic Archipelago Svalbard over the past 130 years, we explored long term trends in persistence and phenology. In total, 448 observations of 105 taxa have been recorded from 28 sites. Recent surveys at 18 of these sites revealed that alien species had disappeared at half of them. Investigations at a further 49 sites characterised by former human activity and/or current tourist landing sites did not reveal any alien species. Patterns of alien species distribution suggest that greater alien species richness is more likely to be aligned with ongoing human inhabitation than sites of transient use. The probability of an alien species being in a more advanced phenological stage increased with higher mean July temperatures. As higher mean July temperatures are positively correlated with more recent year, the latter finding suggests a clear warming effect on the increased reproductive potential of alien plants, and thus an increased potential for spread in Svalbard. Given that both human activity and temperatures are expected to increase in the future, there is need to respond in policy and action to reduce the potential for further alien species introduction and spread in the Arctic

The Chemical Evolution of the La0.6Sr0.4CoO3−δ Surface Under SOFC Operating Conditions and Its Implications for Electrochemical Oxygen Exchange Activity

© The Author(s) 2018Owing to its extraordinary high activity for catalysing the oxygen exchange reaction, strontium doped LaCoO3 (LSC) is one of the most promising materials for solid oxide fuel cell (SOFC) cathodes. However, under SOFC operating conditions this material suffers from performance degradation. This loss of electrochemical activity has been extensively studied in the past and an accumulation of strontium at the LSC surface has been shown to be responsible for most of the degradation effects. The present study sheds further light onto LSC surface changes also occurring under SOFC operating conditions. In-situ near ambient pressure X-ray photoelectron spectroscopy measurements were conducted at temperatures between 400 and 790 °C. Simultaneously, electrochemical impedance measurements were performed to characterise the catalytic activity of the LSC electrode surface for O2 reduction. This combination allowed a correlation of the loss in electro-catalytic activity with the appearance of an additional La-containing Sr-oxide species at the LSC surface. This additional Sr-oxide species preferentially covers electrochemically active Co sites at the surface, and thus very effectively decreases the oxygen exchange performance of LSC. Formation of precipitates, in contrast, was found to play a less important role for the electrochemical degradation of LSC.Fonds zur Förderung der wissenschaftlichen Forschung (FWF)212921411

Regulating pollution with endogenous monitoring

Review in : Journal of Environmental Economics and Management Volume 44, Issue 2, September 2002, Pages 221-241 Abstract : The paper offers a new perspective on nonpoint source pollution by explicitly considering the cost of monitoring individual emissions. The distinction between point and nonpoint source pollution is shown to depend on the cost of monitoring, the environmental cost of pollution, and the impact of monitoring on profits. A regulatory scheme of differential taxation is proposed,International audienceThe paper offers a new perspective on nonpoint source pollution by explicitly considering the cost of monitoring individual emissions. The distinction between point and nonpoint source pollution is shown to depend on the cost of monitoring, the environmental cost of pollution, and the impact of monitoring on profits. A regulatory scheme of differential taxation is proposed, wherein taxes are predicated on whether the agent has installed an emissions monitoring device. The optimal degree of monitoring as well as conditions for optimal regulation in the extreme cases of no monitoring and full monitoring, is identified. © 2002 Elsevier Science (USA)

Land markets and the value of water: Hedonic analysis using repeat sales of farmland

The lack of robust water markets makes it difficult to value irrigation water. Because water rights are appurtenant to land, it is possible to infer the value of water from observed differences in the market price of land. We use panel data on repeat farmland sales in California's San Joaquin Valley to estimate a hedonic regression equation with parcel fixed effects. This controls for sources of omitted variables bias and allows us to recover the value of irrigation water to landowners in our sample. We show that a more traditional cross-sectional regression results in an artificially low value of irrigation water. © The Author (2014)