New Estimates of Federal Government Tangible Capital and Net Investment

Government capital formation raises a number of issues important to national economic well-being, yet the U.S., unlike most advanced countries, does not account for capital in its formal budget documents. We estimate depreciation of government capital using a methodology developed by Hulten and Wykoff which is based on used asset price data. We estimate a federal government net nonresidential capital stock of over $800 billion in 1984, more than 20% higher than estimated by the BEA. We also find much larger net federal investment since World War II than the BEA. The behavior of military and civilian structures and equipment is also examined.We analyze the potential importance of these results for measuring the net national savings rate, national wealth, the trend in government capital formation relative to private capital formation, and the relationship between net investment and deficits.

Population Dynamics and Community Composition of Ammonia Oxidizers in Salt Marshes after the Deepwater Horizon Oil Spill

The recent oil spill in the Gulf of Mexico had significant effects on microbial communities in the Gulf, but impacts on nitrifying communities in adjacent salt marshes have not been investigated. We studied persistent effects of oil on ammonia-oxidizing archaeal (AOA) and bacterial (AOB) communities and their relationship to nitrification rates and soil properties in Louisiana marshes impacted by the Deepwater Horizon oil spill. Soils were collected at oiled and unoiled sites from Louisiana coastal marshes in July 2012, 2 years after the spill, and analyzed for community differences based on ammonia monooxygenase genes (amoA). Terminal Restriction Fragment Polymorphism and DNA sequence analyses revealed significantly different AOA and AOB communities between the three regions, but few differences were found between oiled and unoiled sites. Community composition of nitrifiers was best explained by differences in soil moisture and nitrogen content. Despite the lack of significant oil effects on overall community composition, we identified differences in correlations of individual populations with potential nitrification rates between oiled and unoiled sites that help explain previously published correlation patterns. Our results suggest that exposure to oil, even 2 years post-spill, led to subtle changes in population dynamics. How, or if, these changes may impact ecosystem function in the marshes, however, remains uncertain

Learning, Sticky Inflation, and the Sacrifice Ratio

Over the past forty years, U.S. inflation has exhibited highly persistent movements. Moreover, these shifts in inflation have typically had real consequences, implying a "sacrifice ratio," whereby disinflations are typically associated with recessions and persistent increases in inflation often associated with booms. One hypothesis about the source of the sacrifice ratio is that inflation - and not just the price level - is sticky. Another is that private-sector agents typically must infer changes in inflation objectives indirectly from central bank interest-rate policy. The resulting learning process can lead to a sacrifice ratio trade-off. In this paper, I allow for both sticky inflation and learning in interpreting U.S. macroeconomic developments since 1955. Two key empirical findings are, first, that allowing for learning reduces the evidence for sticky inflation. Second, there is less evidence for sticky inflation in the post-1983 period than earlier. Indeed, in some estimates, there is little evidence of sticky inflation in the period since 1983, although this result is sensitive to the details of the specification. Nonetheless, simulation results suggest that for realistic models, the sacrifice ratio can be accounted for entirely by learning

Photonic microstructures as laser mirrors

Deeply etched 1-D third-order Bragg reflectors have been used as mirrors for broad-area semiconductor lasers operating at 975-nm wavelength. From a threshold and efficiency analysis, we determine the mirror reflectivity to be approximately 95%. The design of the GaAs-based laser structure features three InGaAs quantum wells placed close (0.5 μm) to the surface in order to reduce the required etch depth and facilitate high-quality etching. Despite the shallow design and the proximity of the guided mode to the metal contact, the threshold current density (J_(th) = 220 A/cm^2 for infinite cavity length) and internal loss (α_i = 9±1 cm^(−1)) are very low

The language of experience : a study in methodology

Cover title"April 30, 1955."At head of title: Communications"696"--handwritten on cover"Since the time this MS has been hectographed a few suggestions have been made, particularly by Ithiel de S. Pool, which will rather improve the paper and which will, therefore, be incorporated in the final copy. Further criticisms and suggestions will be appreciated."Includes bibliographical reference

Radio Jet-Ambient Medium Interactions on Parsec Scales in the Blazar 1055+018

As part of our study of the magnetic fields of AGN we have recently observed a large sample of blazars with the Very Long Baseline Array. Here we report the discovery of a striking two-component jet in the source 1055+018, consisting of an inner spine with a transverse magnetic field, and a fragmentary but distinct boundary layer with a longitudinal magnetic field. The polarization distribution in the spine strongly supports shocked-jet models while that in the boundary layer suggests interaction with the surrounding medium. This behavior suggests a new way to understand the differing polarization properties of strong- and weak-lined blazars.Comment: LaTex; 10 pages; 6 figures; reference fix; to appear in ApJL, 518, 1999 June 2

Competition and Post-Transplant Outcomes in Cadaveric Liver Transplantation under the MELD Scoring System

Previous researchers have modelled the decision to accept a donor organ for transplantation as a Markov decision problem, the solution to which is often a control-limit optimal policy: accept any organ whose match quality exceeds some health-dependent threshold; otherwise, wait for another. When competing transplant centers vie for the same organs, the decision rule changes relative to no competition; the relative size of competing centers affects the decision rules as well. Using center-specific graft and patient survival-rate data for cadaveric adult livers in the United States, we have found empirical evidence supporting these predictions.liver transplantation, competition, optimal stopping

THE ROLE OF PRODUCT ATTRIBUTES IN THE AGRICULTURAL NEGOTIATIONS

Marketing, International Relations/Trade,