Breach Remedies, Performance Excuses, and Investment Incentives

Contract law is usually perceived as a strict liability system. When a promisor fails to perform he is held liable even if he is without fault. If, however, an unusual contingency has arisen he may be excused from performing provided that he has taken reasonable precautions. For a setting with uncertain costs of and benefits from performance, it is shown that a fixed price contract is sufficient to generate efficient reliance and precautions incentives under the following legal regime. If the promisor has met the appropriate precaution standard then he is excused if performance fails to be profitable. Alternative regimes, in contrast, where he is excused if performance is inefficient or even is extremely costly distort investment incentives quite generally

Two step ejection of massive stars and the issue of their formation in isolation

In this paper we investigate the combined effect of massive binary ejection from star clusters and a second acceleration of a massive star during a subsequent supernova explosion. We call this the "two-step-ejection" scenario. The main results are: i) Massive field stars produced via the two-step-ejection process can not in the vast majority of cases be traced back to their parent star clusters. These stars can be mistakenly considered as massive stars formed in isolation. ii) The expected O star fraction produced via the two-step-ejection process is of the order of 1-4 per cent, in quantitative agreement with the observed fraction of candidates for isolated-O-star formation. iii) Stars ejected via the two-step-ejection process can get a higher final velocity (up to 1.5-2 times higher) than the pre-supernova velocity of the massive-star binary.Comment: Accepted by MNRA

Does anticipation of government spending matter? Evidence from an expectation augmented VAR

How does private consumption react to an exogenous increase in government expenditure? Standard structural vector autoregressions (SVARs) usually report a positive GDP as well as consumption response, while event studies report a negative consumption response. We investigate in a SVAR whether anticipation of the fiscal shock reverses the sign of this dynamic response to a negative one. As a methodological contribution, we model expectation formation within a SVAR framework. We show for the US that consumption falls in reaction to an expenditure shock once the model allows for one-period-ahead anticipation of this shock. Modelling anticipation of fiscal shocks is thus crucial to correctly capture their macroeconomic effects. Differences in results between event studies and VARs can be explained by missing anticipation in VARs. When re-estimating the two models (with and without anticipation) for non-defense related expenditures, we find a positive consumption response for both models. The implications of our results for macroeconomic theory are briefly discussed. --Fiscal policy,government spending,net revenue,policy anticipation,structural vector autoregression

An overview of virtual city modelling : emerging organisational issues

This paper presents a recent overview of the increasing use of Virtual Reality (VR) technologies for the simulation of urban environments. It builds on previous research conducted on the identification of three-dimensional (3D) city models and offers an analysis of the development, utilization and construction of VR city models. Issues pertaining to advantages, barriers and ownership are identified. The paper describes a case study of the development of a VR model for the city of Newcastle upon Tyne in the UK and outlines the role that academic institutions can play in both the creation and utilization of urban models. The study offers a new approach for the creation, management and update of urban models and reflects on issues which are emerging. Areas for future research are discussed

Long term Arecibo monitoring of the water megamaser in MG J0414+0534

We monitored the 22 GHz maser line in the lensed quasar MG J0414+0534 at z=2.64 with the 300-m Arecibo telescope for almost two years to detect possible additional maser components and to measure a potential velocity drift of the lines. The main maser line profile is complex and can be resolved into a number of broad features with line widths of 30-160 km/s. A new maser component was tentatively detected in October 2008 at a velocity of +470 km/s. After correcting for the estimated lens magnification, we find that the H2O isotropic luminosity of the maser in MG J0414+0534 is about 26,000 solar luminosities, making this source the most luminous ever discovered. Both the main line peak and continuum flux densities are surprisingly stable throughout the period of the observations. An upper limit on the velocity drift of the main peak of the line has been estimated from our observations and is of the order of 2 km/s per year. We discuss the results of the monitoring in terms of the possible nature of the maser emission, associated with an accretion disk or a radio jet. This is the first time that such a study is performed in a water maser source at high redshift, potentially allowing us to study the parsec-scale environment around a powerful radio source at cosmological distances.Comment: 5 pages, 2 figures, to appear in the Proceedings of the IAU Symposium 287, 2012, "Cosmic masers: from OH to H0

Breach Remedies, Performance Excuses, and Investment Incentives

Contract law is usually perceived as a strict liability system. When a promisor fails to perform he is held liable even if he is without fault. If, however, an unusual contingency has arisen he may be excused from performing provided that he has taken reasonable precautions. For a setting with uncertain costs of and benefits from performance, it is shown that a fixed price contract is sufficient to generate efficient reliance and precautions incentives under the following legal regime. If the promisor has met the appropriate precaution standard then he is excused if performance fails to be profitable. Alternative regimes, in contrast, where he is excused if performance is inefficient or even is extremely costly distort investment incentives quite generally.performance excuse; impracticability doctrine; overreliance; efficient precaution

Enhanced temporal resolution in femtosecond dynamic-grating experiments

Recording of gratings by interference of two pump pulses and diffraction of a third probe pulse is useful for investigating ultrafast material phenomena. We demonstrate, in theory and experiment, that the temporal resolution in such configurations does not degrade appreciably even for large angular separation between the pump pulses. Transient Kerr gratings are generated inside calcium fluoride (CaF2) crystals by two interfering femtosecond (pump) pulses at 388 nm and read out by a Bragg-matched probe pulse at 776 nm. The solution to the relevant coupled-mode equations is well corroborated by the experimental results, yielding a value of the Kerr coefficient of ~ 4.4×10^(–7) cm^2/GW for CaF2

Rio - 10 Years After: A Critical Appraisal of Climate Policy

Ten years after the initial Climate Change Convention from Rio in 1992, the developed world is likely to ratify the Kyoto Protocol which has been celebrated as a milestone in climate protection. Standard economic theory, however, casts doubt that Kyoto will go beyond symbolic policy. In this paper we show that the final concretion of the Kyoto Protocol obeys the theoretical prediction: Kyoto more or less boils down to business-as-usual without significant compliance costs to ratifying parties. --climate policy,emission trading,hot air