Martian rampart craters: Morphologic clues for the physical state of the target at time of impact

Current research attempts to describe morphologic features seen in very high resolution Viking Orbiter images of crater ejecta blankets and interiors, in order to constrain the most likely target properties at the time of crater formation. The Viking Orbiter image data set contains approximately 400 frames at a spatial resolution of better than 10 meters per pixel, and 2,200 frames at a resolution of better than 20 meters per pixel, for which the atmosphere was either clear or only slightly obscured. A search is being conducted of all these images and so far has revealed several examples of both interior and exterior features of impact craters that bear on the nature of the ejecta fluidizing medium. Preliminary observations and speculations on the physical state of the Martian regolith at the time of crater formation are given and briefly discussed

Wage Determination in Russia: An Econometric Investigation

Using a firm level dataset from four regions of Russia covering 1996/97, an investigation was carried out into how the surplus created within the firm is divided between profits and wages. An efficient bargaining framework based on the work of Svejnar (1986) is employed which takes into account the alternative wage or outside option available to employees in the firm as well as the value added per employee. Statistical differences in the share of the surplus taken by employees employed in state, private and mixed forms of firms are found. In addition, the results prove sensitive to the presence of outliers and influential observations. A variety of diagnostic methods are employed to identify these influential observations and robust methods are employed to lessen the influence of them. Whereas in practice some of the diagnostic and robust methods utilised proved incapable of identifying or accommodating the gross outlier(s) in the data, the more successful methods included robust regression, Winsorising, the Hadi and Siminoff algorithm, Cook's Distance and Covratio.http://deepblue.lib.umich.edu/bitstream/2027.42/39679/3/wp295.pd

Some Evidence on the Importance of Sticky Prices

We examine the frequency of price changes for 350 categories of goods and services covering about 70% of consumer spending, based on unpublished data from the BLS for 1995 to 1997. Compared with previous studies we find much more frequent price changes, with half of prices lasting less than 4.3 months. The frequency of price changes differs dramatically across categories. We exploit this variation to ask how inflation for 'flexible-price goods' (goods with frequent changes in individual prices) differs from inflation for 'sticky-price goods' (those displaying infrequent price changes). Compared to the predictions of popular sticky price models, actual inflation rates are far more volatile and transient, particularly for sticky-price goods. The data appendix for this paper can be found at http://www.nber.org/data-appendix/w9069/

Quantifying Quality Growth

We introduce an instrumental variables approach to estimate the importance of unmeasured quality growth for a set of 66 durable consumer goods. Our instrument is based on predicting which of these 66 goods will display rapid quality growth. Using pooled cross- relatively sections of households in the 1980 through 1996 U.S. Consumer Expenditure Surveys, we estimate quality Engel curves' for 66 durable consumer goods based on the extent richer households pay more for a good, conditional on purchasing. We use the slopes of these curves to predict the rate of quality-upgrading. Just as if households are ascending these quality Engel curves over time, we find that the average price paid rises faster for goods with steeper quality slopes. BLS prices likewise increase more quickly for goods with steeper quality slopes, suggesting the BLS does not fully net out the impact of quality-upgrading on prices paid. We estimate that quality growth averages about 3.7% per year for our goods, with about 60% of this, or 2.2% per year, showing up as higher inflation rather than higher real growth.

Wage Determination in Russia: An Econometric Investigation

Using a firm level dataset from four regions of Russia covering 1996/97, an investigation was carried out into how the surplus created within the firm is divided between profits and wages. An efficient bargaining framework based on the work of Svejnar (1986) is employed which takes into account the alternative wage or outside option available to employees in the firm as well as the value added per employee. Statistical differences in the share of the surplus taken by employees employed in state, private and mixed forms of firms are found. In addition, the results prove sensitive to the presence of outliers and influential observations. A variety of diagnostic methods are employed to identify these influential observations and robust methods are employed to lessen the influence of them. Whereas in practice some of the diagnostic and robust methods utilised proved incapable of identifying or accommodating the gross outlier(s) in the data, the more successful methods included robust regression, Winsorising, the Hadi and Siminoff algorithm, Cook's Distance and Covratio.Russian labour markets, efficient bargaining, outliers, regression diagnostics, robust regression

New very high resolution radar studies of the Moon

As part of an effort to further understand the geologic utility of radar studies of the terrestrial planets, investigators at the Hawaii Institute of Geophysics are collaborating with NEROC Haystack Observatory, MIT and the Jet Propulsion Laboratory in the analysis of existing 3.8 and 70 cm radar images of the Moon, and in the acquisition of new data for selected lunar targets. The intent is to obtain multi-polarization radar images at resolutions approaching 75 meters (3.8 cm wavelength) and 400 meters (70 cm wavelength) for the Apollo landing sites (thereby exploiting available ground truth) or regions covered by the metric camera and geochemical experiments onboard the command modules of Apollos 15, 16 and 17. These data were collected in both like- and cross-polarizations, and, in the case of the 70 cm data, permit the phase records to be used to assess the scattering properties of the surface. The distribution of surface units on the Moon that show a mismatch between the surface implied by like- and cross-polarized scattering data is being analyzed, based on the scattering models of Evans and Hagfors

Bistability through triadic closure

We propose and analyse a class of evolving network models suitable for describing a dynamic topological structure. Applications include telecommunication, on-line social behaviour and information processing in neuroscience. We model the evolving network as a discrete time Markov chain, and study a very general framework where, conditioned on the current state, edges appear or disappear independently at the next timestep. We show how to exploit symmetries in the microscopic, localized rules in order to obtain conjugate classes of random graphs that simplify analysis and calibration of a model. Further, we develop a mean field theory for describing network evolution. For a simple but realistic scenario incorporating the triadic closure effect that has been empirically observed by social scientists (friends of friends tend to become friends), the mean field theory predicts bistable dynamics, and computational results confirm this prediction. We also discuss the calibration issue for a set of real cell phone data, and find support for a stratified model, where individuals are assigned to one of two distinct groups having different within-group and across-group dynamics