Proton Single Particle Energy Shifts due to Coulomb Correlations

A theoretically consistent approach to the calculation of the Coulomb correlation corrections to the single--particle energies is presented. New contributions to the single--particle energies previously overlooked in the literature are now identified and taken into account. We show that the interplay between the Coulomb interaction and the strong interaction, which is enhanced in the nuclear surface, leads to an upward shift of the proton single--particle levels. This shift affects the position of the calculated proton drip line, a shift towards decreasing $Z$. We describe briefly a similar mechanism which is at work for neutron levels. The same mechanism is responsible for significant corrections to the mass difference of the mirror nuclei (Nolen--Schiffer anomaly) and to the effective proton mass.Comment: 11 pages + 1 figur

Propagation and smoothing of shocks in alternative social security systems

Even with well-developed capital markets, there is no private market mechanism for trading between current and future generations. This generates a potential role for public old-age pension systems to spread economic and demographic shocks among different generations. This paper evaluates how different systems smooth and propagate shocks to productivity, fertility, mortality and migration in a realistic OLG model. We use reductions in the variance of wealth equivalents to measure performance, starting with the existing U.S. system as a unifying framework, in which we vary how much taxes and benefits adjust, and which we then compare to the existing German and Swedish systems. We find that system design and shock type are key factors. The German system and the benefit-adjustment-only U.S. system best smooth productivity shocks, which are by far the most important shocks. Overall, the German system performs best, while the Swedish system, which includes a buffer stock to relax annual budget constraints, performs rather poorly. Focusing on the U.S. system, reliance solely on tax adjustment fares best for mortality and migration shocks, while equal reliance on tax and benefit adjustments is best for fertility shocks

Effects of non-adiabaticity on the voltage generated by a moving domain wall

We determine the voltage generated by a field-driven domain wall, taking into account non-adiabatic corrections to the motive force induced by the time-dependent spin Berry phase. Both the diffusive and ballistic transport regimes are considered. We find that that the non-adiabatic corrections, together with the contributions due to spin relaxation, determine the voltage for driving fields smaller than the Walker breakdown limit.Comment: 8 pages, 3 figure

Tax Reform, Investment, and the Value of the Firm

The taxation of corporate assets is well understood to influence investment and firm valuation. This paper explores the consequences of postwar U.S. tax changes in a dynamic model which incorporates costs of adjustment and investor expectations of future tax reforms and macroeconomic variability.When viewed in a dynamic context, the tax code can have very different incentives than those implied by the usual static analysis. Simulation results suggest that investment is sensitive to future tax changes and business-cycle movements. The paper also illustrates the implications of this analysis for the design of tax reforms.

Perfect Taxation with Imperfect Competition

This paper analyzes features of perfect taxation also known as optimal taxation when one or more private markets is imperfectly competitive. Governments with perfect information and access to lump-sum taxes can provide corrective subsidies that render outcomes efficient in the presence of imperfect competition. Relaxing either of these two conditions removes the government's ability to support efficient resource allocation and changes the perfect policy response. When governments cannot use lump-sum taxes, perfect tax policies represent compromises between the benefits of subsidizing output in the imperfectly competitive sectors of the economy and the costs of imposing higher taxes elsewhere. This tradeoff is formally identical for ad valorem and specific taxes, even though ad valorem taxation is welfare superior to specific taxation in the presence of imperfect competition. When governments have uncertain knowledge of the degree of competition in product markets, perfect corrective tax policy is generally of smaller magnitude than that when the degree of competition is known with certainty.

Anticipated Tax Changes and the Timing of Investment

This paper analyzes the short-run and long-run effects of corporate tax changes over the last three decades and the likely consequences of proposed future tax changes. Consideration of short-run effects of tax reform on investment and market value requires a careful analysis of three elements of behavior that are normally omitted from long run analyses: the state of investor expectations, the time lags involved in putting new capital in place, and the tax law's distinctions between new and old capital. The model described in this paper considers investment in equipment and investment in plant separately, and does so under different specifications of investor expectations. Our results for the period 1954-1985 suggest that investors did take account of fluctuations in profitability, real interest rates, and the tax code in making their investment plans. We examine the consequences of the nonindexation of depreciation benefits as well as the introduction of the investment tax credit and the Accelerated Cost Recovery System by simulating the corporate sector's performance in the absence of these features. In addition, we analyze the effects of changing the tax code in 1986 along the lines proposed in the Bradley-Gephardt "Fair Tax" plan, the Treasury II plan, and the Rostenkowski plan, H.R. 3838. The simulation results suggest that all three plans would reduce fixed investment in the short run, with the reduction coming primarily in equipment. At the same time, the simulations predict large wind-falls for existing capital assets under all three reform proposals.

A Century of National Park Conflict: Class, Geography, and the Changing Values of Conservation Discourse in Maine

Conservation interests have been promoting national park creation in Maine ever since the early 1900s. The only successful push for a national park in the state culminated one hundred years ago in the creation of today’s Acadia National Park in 1916. In the last century, Maine’s North Woods have been the site of four distinct national park debates. Mt. Katahdin was the subject of a hotly contested park proposal in the 1930s, as was the Allagash River in the 1950s and 60s. In 1994 a group called RESTORE: The North Woods began promoting a widely opposed 3.2 million-acre national park in the North Woods region. Today, fervent debate surrounds a proposal by Elliotsville Plantation Inc. for a much smaller national park in the area. This thesis will demonstrate that today’s public park debate is unique in that both park supporters and opponents appeal primarily to economic development arguments to justify their positions. Why is this and what are the repercussions of this particular public framing of the debate? This thesis will answer these questions through a combination of historical archival research into past park debates and contemporary interviews concerning today’s debate, allowing me to trace the various value systems that have been a part of each of Maine’s historical and contemporary park debates. As it turns out, the particular class and geographic dynamics of conservation in Maine are critical to understanding the focus on economic development in today’s debate, and this framing has serious negative consequences