Prices vs. Quantities with incomplete enforcement and different enforcement probabilities

Regulating inter-country externalities, like climate change, raises various enforcement problems. It is often argued that international pricebased regulations (e.g. emission taxes) are more difficult to enforce than quantity-based regulations (e.g. tradable pollution permits). In this paper, we analyze the relative performance of price-based and quantity-based instruments for cases where costs and benefits are uncertain and enforcement of quantity regimes is stricter than for price-based regimes. We show that under these conditions, instrument choice solely based on the relative slopes of the marginal costs can be inefficient. If enforcement probabilities differ, rational policy choice should also take into account the level of the marginal benefit curve, as well as institutional parameters. In contrast to earlier analyses on Prices vs. Quantities, we find that the difference in welfare for both policy instruments also depends on the variance of the marginal abatement costs. Furthermore, numerical simulations of our stylized model suggest that, for climate policies, quantity-regulations might well be preferable to price-based approaches after all. --market-based instruments,incomplete enforcement,environmental regulation,uncertainty

Prices vs. Quantities with Fiscal Cushioning

Regulating international externalities, like climate change, raises various enforcement problems. It is often argued that international price-based regulations (e.g. emission taxes) are more difficult to enforce than quantity-based regulations (e.g. tradable pollution permits). In this paper, we analyze the relative performance of price-based and quantity-based instruments when costs and benefits are uncertain and enforcement of quantity regimes is stricter than that of price regimes. We show that under these conditions, instrument choice solely based on the relative slopes of the marginal curves can yield inefficient results. If policy enforcement differs, rational policy choice should also take into account the level of the marginal benefit curve, as well as institutional parameters. In contrast to earlier analyses on "Prices vs. Quantities", we find that the choice of instrument also depends on the variance of the marginal abatement costs. Numerical simulations of our stylized model suggest that, for climate policies, quantity-regulations might well be preferable to price-based approaches after all.market-based instruments, incomplete enforcement, uncertainty, environmental regulation

Atlantic Water advection versus sea-ice advances in the eastern Fram Strait during the last 9 ka - multiproxy evidence for a two-phase Holocene

A sediment core from the West Spitsbergen continental margin was studied to reconstruct climate and paleoceanographic variability during the last ~9 ka in the eastern Fram Strait. Our multiproxy evidence suggests that the establishment of the modern oceanographic configuration in the eastern Fram Strait occurred stepwise, in response to the postglacial sea-level rise and the related onset of modern sea-ice production on the shallow Siberian shelves. The late Early and Mid Holocene interval (9 to 5 ka) was generally characterized by relatively unstable conditions. High abundance of the subpolar planktic foraminifer species Turborotalita quinqueloba implies strong intensity of Atlantic Water (AW) inflow with high productivity and/or high AW temperatures, resulting in a strong heat flux to the Arctic. A series of short-lived cooling events (8.2, 6.9. and 6.1 ka) occurred superimposed on the warm late Early and Mid Holocene conditions. Our proxy data imply that simultaneous to the complete postglacial flooding of Arctic shallow shelves and the initiation of modern sea-ice production, strong advance of polar waters initiated modern oceanographic conditions in the eastern Fram Strait at ~5.2 ka. The Late Holocene was marked by the dominance of the polar planktic foraminifer species Neogloboquadrina pachyderma, a significant expansion of sea ice/icebergs, and strong stratification of the water column. Although planktic foraminiferal assemblages as well as sea surface and subsurface temperatures suggest a return of slightly strengthened advection of subsurface Atlantic Water after 3 ka, a relatively stable cold-water layer prevailed at the sea surface and the study site was probably located within the seasonally fluctuating marginal ice zone during the Neoglacial period

Prices vs. quantities with fiscal cushioning

Regulating international externalities, like climate change, raises various enforcement problems. It is often argued that international price-based regulations (e.g. emission taxes) are more difficult to enforce than quantity-based regulations (e.g. tradable pollution permits). In this paper, we analyze the relative performance of price-based and quantity-based instruments when costs and benefits are uncertain and enforcement of quantity regimes is stricter than that of price regimes. We show that under these conditions, instrument choice solely based on the relative slopes of the marginal curves can yield inefficient results. If policy enforcement differs, rational policy choice should also take into account the level of the marginal benefit curve, as well as institutional parameters. In contrast to earlier analyses on "Prices vs. Quantities", we find that the choice of instrument also depends on the variance of the marginal abatement costs. Numerical simulations of our stylized model suggest that, for climate policies, quantity-regulations might well be preferable to price-based approaches after all

Regenerative potential of epicardium-derived extracellular vesicles mediated by conserved miRNA transfer

AIMS: After a myocardial infarction, the adult human heart lacks sufficient regenerative capacity to restore lost tissue, leading to heart failure progression. Finding novel ways to reprogram adult cardiomyocytes into a regenerative state is a major therapeutic goal. The epicardium, the outermost layer of the heart, contributes cardiovascular cell types to the forming heart and is a source of trophic signals to promote heart muscle growth during embryonic development. The epicardium is also essential for heart regeneration in zebrafish and neonatal mice and can be reactivated after injury in adult hearts to improve outcome. A recently identified mechanism of cell–cell communication and signalling is that mediated by extracellular vesicles (EVs). Here, we aimed to investigate epicardial signalling via EV release in response to cardiac injury and as a means to optimize cardiac repair and regeneration. METHODS AND RESULTS: We isolated epicardial EVs from mouse and human sources and targeted the cardiomyocyte population. Epicardial EVs enhanced proliferation in H9C2 cells and in primary neonatal murine cardiomyocytes in vitro and promoted cell cycle re-entry when injected into the injured area of infarcted neonatal hearts. These EVs also enhanced regeneration in cryoinjured engineered human myocardium (EHM) as a novel model of human myocardial injury. Deep RNA-sequencing of epicardial EV cargo revealed conserved microRNAs (miRs) between human and mouse epicardial-derived exosomes, and the effects on cell cycle re-entry were recapitulated by administration of cargo miR-30a, miR-100, miR-27a, and miR-30e to human stem cell-derived cardiomyocytes and cryoinjured EHM constructs. CONCLUSION: Here, we describe the first characterization of epicardial EV secretion, which can signal to promote proliferation of cardiomyocytes in infarcted mouse hearts and in a human model of myocardial injury, resulting in enhanced contractile function. Analysis of exosome cargo in mouse and human identified conserved pro-regenerative miRs, which in combination recapitulated the therapeutic effects of promoting cardiomyocyte proliferation

Comparison of different reconstruction algorithms for three-dimensional ultrasound imaging in a neurosurgical setting

Background Freehand three-dimensional ultrasound imaging (3D-US) is increasingly used in image-guided surgery. During image acquisition, a set of B-scans is acquired that is distributed in a non-parallel manner over the area of interest. Reconstructing these images into a regular array allows 3D visualization. However, the reconstruction process may introduce artefacts and may therefore reduce image quality. The aim of the study is to compare different algorithms with respect to image quality and diagnostic value for image guidance in neurosurgery. Methods 3D-US data sets were acquired during surgery of various intracerebral lesions using an integrated ultrasound-navigation device. They were stored for post-hoc evaluation. Five different reconstruction algorithms, a standard multiplanar reconstruction with interpolation (MPR), a pixel nearest neighbour method (PNN), a voxel nearest neighbour method (VNN) and two voxel based distance-weighted algorithms (VNN2 and DW) were tested with respect to image quality and artefact formation. The capability of the algorithm to fill gaps within the sample volume was investigated and a clinical evaluation with respect to the diagnostic value of the reconstructed images was performed. Results MPR was significantly worse than the other algorithms in filling gaps. In an image subtraction test, VNN2 and DW reliably reconstructed images even if large amounts of data were missing. However, the quality of the reconstruction improved, if data acquisition was performed in a structured manner. When evaluating the diagnostic value of reconstructed axial, sagittal and coronal views, VNN2 and DW were judged to be significantly better than MPR and VNN. Conclusion VNN2 and DW could be identified as robust algorithms that generate reconstructed US images with a high diagnostic value. These algorithms improve the utility and reliability of 3D-US imaging during intraoperative navigation