What model for entry in first-price auctions? A nonparametric approach

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Quantile Models with Endogeneity

In this article, we review quantile models with endogeneity. We focus on models that achieve identification through the use of instrumental variables and discuss conditions under which partial and point identification are obtained. We discuss key conditions, which include monotonicity and full-rank-type conditions, in detail. In providing this review, we update the identification results of Chernozhukov & Hansen (2005). We illustrate the modeling assumptions through economically motivated examples. We also briefly review the literature on estimation and inference

A multi-model analysis of vertical ozone profiles

A multi-model study of the long-range transport of ozone and its precursors from major anthropogenic source regions was coordinated by the Task Force on Hemispheric Transport of Air Pollution (TF HTAP) under the Convention on Long-range Transboundary Air Pollution (LRTAP). Vertical profiles of ozone at 12-h intervals from 2001 are available from twelve of the models contributing to this study and are compared here with observed profiles from ozonesondes. The contributions from each major source region are analysed for selected sondes, and this analysis is supplemented by retroplume calculations using the FLEXPART Lagrangian particle dispersion model to provide insight into the origin of ozone transport events and the cause of differences between the models and observations. In the boundary layer ozone levels are in general strongly affected by regional sources and sinks. With a considerably longer lifetime in the free troposphere, ozone here is to a much larger extent affected by processes on a larger scale such as intercontinental transport and exchange with the stratosphere. Such individual events are difficult to trace over several days or weeks of transport. This may explain why statistical relationships between models and ozonesonde measurements are far less satisfactory than shown in previous studies for surface measurements at all seasons. The lowest bias between model-calculated ozone profiles and the ozonesonde measurements is seen in the winter and autumn months. Following the increase in photochemical activity in the spring and summer months, the spread in model results increases, and the agreement between ozonesonde measurements and the individual models deteriorates further. At selected sites calculated contributions to ozone levels in the free troposphere from intercontinental transport are shown. Intercontinental transport is identified based on differences in model calculations with unperturbed emissions and emissions reduced by 20% by region. Intercontinental transport of ozone is finally determined based on differences in model ensemble calculations. With emissions perturbed by 20% per region, calculated intercontinental contributions to ozone in the free troposphere range from less than 1 ppb to 3 ppb, with small contributions in winter. The results are corroborated by the retroplume calculations. At several locations the seasonal contributions to ozone in the free troposphere from intercontinental transport differ from what was shown earlier at the surface using the same dataset. The large spread in model results points to a need of further evaluation of the chemical and physical processes in order to improve the credibility of global model results

Building of tensor Green’s functions for solving of radiation problem from slot in wall of sending structure

The building of general algorithm solving problems of radiation from a longitudinal slot in the wide wall of rectangular waveguide is considered. An algorithm is created on the basis of integral theorem of vectorial theory of diffraction where the tensor Green’s function is used. It is therefore necessary to consider the general method of construction of Green’s tensor function of waveguide and half-space

Direct short wave radiative forcing of sulfate aerosol over europe from 1900 to 2000

On the basis of historical simulations of the atmospheric distribution of sulfate aerosol over Europe, we have estimated the evolution of the direct shortwave radiative forcing due to sulfate aerosol from 1900 to the present day. Following the trend of atmospheric sulfate burden, the radiative forcing reaches its peak in the 1980s. Since then, environmental policies regulating SOx emissions successfully reduced the atmospheric load. On average, the forcing of the year 2000, representing present day, equals that of the 1950s. Spatially, the forcing maxima experienced a shift from the northwest to the southeast during the century. The ship emissions of sulfur keep increasing since the 1980s, hence their relative contribution to the sulfate load and radiative forcing constantly increased, from 3% in the 1980s to over 10% in the year 2000. Forcing is strongest during summertime, with a seasonal mean of −2.7 W m−2 in the 1980s and −1.2 W m−2 in summer 2000. The mean forcing efficiency is slightly reduced from −246 W (g sulfate)−1 in the 1900s to −230 W (g sulfate)−1 in the year 2000, and it declines with changed geographical distribution of sulfur emissions