Measurements of underwater piling noise during nearshore windfarm construction in the UK potential impact on marine mammals in compliance with German UBA limit

Offshore construction work, such as pile and conductor driving, can potentially cause acoustic disturbance to marine mammals, such as cetaceans (whales, dolphins and por-poises), the odontocetes (toothed cetaceans) of which rely on the underwater sound field for spatial orientation, navigation, prey capture, communication, and predator avoidance. Disturbance ranges from behavioural changes, masking of communication signals, and temporary or even permanent hearing loss. There is currently no specific legal noise threshold in UK waters, but the Marine Management Organisation (MMO) has stipulated the requirement for noise monitoring during pile-driving operations when some windfarms are constructed. Measurements presented in this paper were taken during nearshore pile driving in the UK from a support vessel located 750 m from each pile (wind-turbine foun-dation). Results were compared with a threshold issued by the German Federal Environ-ment Agency (UBA). Noise level beyond the measurement location was predicted using a numerical model. Comparing results with the Southall criteria (Southall, B. L., et al., Ma-rine Mammal Noise Exposure Criteria: Initial Scientific Recommendations. Aquatic Mam-mals, 33 (4), 2007), the Joint Nature Conservation Committee (JNCC) 500 m exclusion zone offered protection for most of marine mammals during pile driving events in this particular case. Keywords: Underwater piling noise, wind-farm, marine mammals, UBA limi

On sharing NATO defence burdens in the 1990s and beyond

This article investigates NATO burden sharing in the 1990s in light of strategic, technological, political and membership changes. Both an ability-to-pay and a benefits-received analysis of burden sharing are conducted. During 1990-99, there is no evidence of disproportionate burden sharing, where the large allies shoulder the burdens of the small. Nevertheless, the theoretical model predicts that this disproportionality will plague NATO in the near future. Thus far, there is still a significant concordance between benefits received and defence burdens carried. When alternative expansion scenarios are studied, the extent of disproportionality of burden sharing increases as NATO grows in size. A broader security burden-sharing measure is devised and tested; based on this broader measure, there is still no disproportionality evident in the recent past.

An insider's view of the political economy of the too big to fail doctrine

An explanation of the relationship between interbank exposure and the too big to fail doctrine, with an examination of the interbank exposure of U.S. banks between March 1984 and March 1990.Bank supervision ; Bank failures

A Note on Adapting Propensity Score Matching and Selection Models to Choice Based Samples

The probability of selection into treatment plays an important role in matching and selection models. However, this probability can often not be consistently estimated, because of choice-based sampling designs with unknown sampling weights. This note establishes that the selection and matching procedures can be implemented using propensity scores fit on choice-based samples with misspecified weights, because the odds ratio of the propensity score fit on the choice-based sample is monotonically related to the odds ratio of the true propensity scores.choice-based sampling, matching models, propensity scores, selection models

EconPort: Creating and Maintaining a Knowledge Commons

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Divorcing money from monetary policy

Many central banks implement monetary policy in a way that maintains a tight link between the stock of money and the short-term interest rate. In particular, their implementation procedures require that the supply of reserve balances be set precisely in order to implement the target interest rate. Because bank reserves play other key roles in the economy, this link can create tensions with other important objectives, especially in times of acute market stress. This article considers an alternative approach to monetary policy implementation -- known as a "floor system" -- that can reduce or even eliminate these tensions. The authors explain how this approach, in which the central bank pays interest on reserves at the target interest rate, "divorces" the supply of money from the conduct of monetary policy. The quantity of bank reserves can then be set according to the payment or liquidity needs of financial markets. By removing the opportunity cost of holding reserves, the floor system also encourages the efficient allocation of resources in the economy.Monetary policy ; Banks and banking, Central ; Money supply ; Bank reserves ; Interest rates

The Perception of Globally Coherent Motion

How do human observers perceive a coherent pattern of motion from a disparate set of local motion measures? Our research has examined how ambiguous motion signals along straight contours are spatially integrated to obtain a globally coherent perception of motion. Observers viewed displays containing a large number of apertures, with each aperture containing one or more contours whose orientations and velocities could be independently specified. The total pattern of the contour trajectories across the individual apertures was manipulated to produce globally coherent motions, such as rotations, expansions, or translations. For displays containing only straight contours extending to the circumferences of the apertures, observers' reports of global motion direction were biased whenever the sampling of contour orientations was asymmetric relative to the direction of motion. Performance was improved by the presence of identifiable features, such as line ends or crossings, whose trajectories could be tracked over time. The reports of our observers were consistent with a pooling process involving a vector average of measures of the component of velocity normal to contour orientation, rather than with the predictions of the intersection-of-constraints analysis in velocity space.Air Force Office of Scientific Research (90-0175, 89-0016); National Science Foundation, Office of Naval Research, Air Force Office of Scientific Research (BNS-8908426