The variation of the doublet separation of H 1/α with the change in current density

Thesis (M.A.)--Boston Universit

Analysis of Policy Issues Relating to Public Investment in Private Freight Infrastructure, MTI Report 99-03

The Norman Y. Mineta International Institute for Surface Transportation Policy Studies (IISTPS) at San José State University conducted this study to review the issues and implications involved in the investment of public funds in private freight infrastructure. After thorough legal research, the project team reached the following conclusions: LEGAL ANALYSIS: The California legislature has the legal power to invest public funds in privately-owned freight infrastructure projects State Highway funds, excepting gas tax revenues, may be used for investment in freight infrastructure projects. Gas tax revenues are restricted to highway use by current interpretations of the California Constitution. A challenge to this interpretation is not recommended. Gas tax revenues may be invested in roadway segments of freight infrastructure projects. RECOMMENDATIONS An analytical system of guidelines should be developed to score and evaluate any proposed freight infrastructure project. Economic development must be included in these scoring guidelines. Public agencies should maintain political contacts in order to control the political short-circuits of the planning process. The California Department of Transportation should develop a Freight Improvement Priority System for the purpose of prioritizing all freight improvement projects

Ionization Front Instabilities in Primordial H II Regions

Radiative cooling by metals in shocked gas mediates the formation of ionization front instabilities in the galaxy today that are responsible for a variety of phenomena in the interstellar medium, from the morphologies of nebulae to triggered star formation in molecular clouds. An important question in early reionization and chemical enrichment of the intergalactic medium is whether such instabilities arose in the H II regions of the first stars and primeval galaxies, which were devoid of metals. We present three-dimensional numerical simulations that reveal both shadow and thin-shell instabilities readily formed in primordial gas. We find that the hard UV spectra of Population III stars broadened primordial ionization fronts, causing H2 formation capable of inciting violent thin- shell instabilities in D-type fronts, even in the presence of intense Lyman-Werner flux. The high post- front gas temperatures associated with He ionization sustained and exacerbated shadow instabilities, unaided by molecular hydrogen cooling. Our models indicate that metals eclipsed H2 cooling in I-front instabilities at modest concentrations, from 0.001- 0.01 solar. We conclude that ionization front instabilities were prominent in the H II regions of the first stars and galaxies, influencing the escape of ionizing radiation and metals into the early universe.Comment: 13 pages, 11 figures, accepted by ApJ with minor revision

Product Differentiation, Cost-Reducing Mergers, and Consumer Welfare

Cost synergies are an explicitly recognized justification for a two-firm merger and empirical techniques are now widely used to assess the impact of cost-reducing mergers on prices and welfare in the postmerger market. We show that if the merger occurs in a vertically product differentiated market then the merger will lead to a reduction in product offerings that limits the usefulness of pre-merger empirical estimates. Indeed, we further show that in such markets, two-firm merges will lead to higher prices regardless of the merger’s cost-savings. We show that our results may obtain even when we allow for post-merger entry.mergers, cost synergies, vertical product differentiation

Accountability and corruption : political institutions matter

Using a cross-country panel, Lederman, Loayza, and Soares examine the determinants of corruption, paying particular attention to political institutions that increase political accountability. Previous empirical studies have not analyzed the role of political institutions, even though both the political science and the theoretical economics literature have indicated their importance in determining corruption. The main theoretical hypothesis guiding the authors?empirical investigation is that political institutions affect corruption through two channels: political accountability and the structure of the provision of public goods. The results suggest that political institutions are extremely important in determining the prevalence of corruption: democracy, parliamentary systems, political stability, and freedom of the press are all associated with lower corruption. In addition, the authors show that common findings of the earlier empirical literature on the determinants of corruption?elated to openness and legal tradition?o not hold once political variables are taken into account.Corruption&Anitcorruption Law,Decentralization,Pharmaceuticals&Pharmacoeconomics,Public Sector Corruption&Anticorruption Measures,Poverty Monitoring&Analysis,National Governance,Governance Indicators,Pharmaceuticals&Pharmacoeconomics,Corruption&Anitcorruption Law,Public Sector Corruption&Anticorruption Measures

How the First Stars Regulated Local Star Formation I: Radiative Feedback

We present numerical simulations of how a 120 M$_\odot$ primordial star regulates star formation in nearby cosmological halos at $z \sim$ 20 by photoevaporation. Our models include nine-species primordial chemistry and self-consistent multifrequency conservative transfer of UV photons with all relevant radiative processes. Whether or not new stars form in halos clustered around a Population III star ultimately depends on their core densities and proximity to the star. Diffuse halos with central densities below 2 - 3 cm$^{-3}$ are completely ionized and evaporated anywhere in the cluster. Evolved halos with core densities above 2000 cm$^{-3}$ are impervious to both ionizing and Lyman-Werner flux at most distances from the star and collapse as quickly as they would in its absence. Star formation in halos of intermediate density can be either promoted or suppressed depending on how the I-front remnant shock compresses, deforms and enriches the core with H$_2$. We find that the 120 M$_\odot$ star photodissociates H$_2$ in most halos in the cluster but that catalysis by H- restores it a few hundred kyr after the death of the star, with little effect on star formation. Our models exhibit significant departures from previous one-dimensional spherically-symmetric simulations, which are prone to serious errors due to unphysical geometric focusing effects.Comment: 20 pages, 19 figures, accepted by ApJ, title and abstract change

Quantity and Elasticity Spillovers onto the Labor Market: Theory and Evidence on Sluggishness

Firms' beliefs that they may be unable to sell as much as they would like at the market price leads not only to a quantity spillover (even when prices are flexible) but also to a spillover of product demand elasticity onto the elasticity of labor demand. Hence, optimal firm behavior can be expected to produce a negative correlation between the (absolute value of) the wage elasticity and the unemployment rate. This hypothesis is tested on three sets of data. 1) For low-skilled workers in the United States in 1969 there is weak support for this hypothesis; 2) In time-series data for the U.S. there is no evidence for the hypothesis (there is essentially no cyclical variability in the elasticity); and 3) In time-series data for the United Kingdom there is fairly strong evidence supporting it. We also find that, in both the U.S. and the U.K., the demand elasticity for labor decreased in the 1970s to an extent that does not appear to be explained by changes in other factor prices.