The algebra of rewriting for presentations of inverse monoids

We describe a formalism, using groupoids, for the study of rewriting for presentations of inverse monoids, that is based on the Squier complex construction for monoid presentations. We introduce the class of pseudoregular groupoids, an example of which now arises as the fundamental groupoid of our version of the Squier complex. A further key ingredient is the factorisation of the presentation map from a free inverse monoid as the composition of an idempotent pure map and an idempotent separating map. The relation module of a presentation is then defined as the abelianised kernel of this idempotent separating map. We then use the properties of idempotent separating maps to derive a free presentation of the relation module. The construction of its kernel - the module of identities - uses further facts about pseudoregular groupoids.Comment: 22 page

Just Transitions in a Public School Food System: The Case of Buffalo, New York

This article examines the public school food system in Buffalo, New York, for a just transition (Movement Generation, n. d.). School food programs built on just transition characteristics democratize engagement, decentralize decision-making, diversify the economy, decrease consumption, and redistribute resources and power

Energy Tax Credits and Residential Conservation Investment

We model the decision to invest in residential energy conservation capital as an irreversible investment in the face of price uncertainty. The irreversible nature of this investment means that there is a value to waiting to invest (an option value) which helps explain the low rate of conservation investment as a result of the residential energy tax credit. Simulations suggest that a tax credit of the type implemented from 1978 through 1985 will not increase conservation investment significantly. We investigate the empirical evidence on the effectiveness of credits using data from a panel data set of roughly 38,000 individual tax returns followed over a three year period from 1979-1981. Unlike previous work, we find that the energy tax credit is statistically significant in explaining the probability of investing. Our estimates suggest that increasing the federal credit by 10 percentage points would increase the percentage of households claiming the credit from 5.7% to 7.1%.

Distributional Impacts in a Comprehensive Climate Policy Package

This paper provides a simple analytic approach for measuring the burden of carbon pricing that does not require sophisticated and numerically intensive economic models but which is not limited to restrictive assumptions of forward shifting of carbon prices. We also show how to adjust for the capital income bias contained in the Consumer Expenditure Survey, a bias towards regressivity in carbon pricing due to underreporting of capital income in higher income deciles in the Survey. Many distributional analyses of carbon pricing focus on the uses-side incidence of carbon pricing. This is the differential burden resulting from heterogeneity in consumption across households. Once one allows for sources-side incidence (i.e. differential impacts of changes in real factor prices), carbon policies look more progressive. Perhaps more important than the findings from any one scenario, our results on the progressivity of the leading cap and trade proposals are robust to the assumptions made on the relative importance of uses and sources side heterogeneity.

The Incidence of a U.S. Carbon Tax: A Lifetime and Regional Analysis

This paper measures the direct and indirect incidence of a carbon tax using current income and two measures of lifetime income to rank households. Our results suggest that carbon taxes are more regressive when annual income is used as a measure of economic welfare than when proxies for lifetime income are used. Further, the direct component of the tax, in any given year, is significantly more regressive than the indirect component. In fact, for 1987, the indirect component of the tax is mildly progressive. We observe a modest shift over time with the direct component of carbon taxes becoming less regressive and the indirect component becoming more regressive. These effects mostly offset each other and the distribution of the total tax burden has not changed much over time. In addition we find that regional variation has fluctuated over the years of our anlaysis. By 2003 there is little systematic variation in carbon tax burdens across regions of the country.

Hysteresis loops of magnetic thin films with perpendicular anisotropy

We model the magnetization of quasi two-dimensional systems with easy perpendicular (z-)axis anisotropy upon change of external magnetic field along z. The model is derived from the Landau-Lifshitz-Gilbert equation for magnetization evolution, written in closed form in terms of the z component of the magnetization only. The model includes--in addition to the external field--magnetic exchange, dipolar interactions and structural disorder. The phase diagram in the disorder/interaction strength plane is presented, and the different qualitative regimes are analyzed. The results compare very well with observed experimental hysteresis loops and spatial magnetization patterns, as for instance for the case of Co-Pt multilayers.Comment: 8 pages, 8 figure

Control of dissipation in superconducting films by magnetic stray fields

Hybrid superconducting/magnetic nanostructures on Si substrates have been built with identical physical dimensions but different magnetic configurations. By constructing arrays based on Co-dots with in-plane, out-of-plane, and vortex state magnetic configurations, the stray fields are systematically tuned. Dissipation in the mixed state of superconductors can be decreased (increased) by several orders of magnitude by decreasing (increasing) the stray magnetic fields. Furthermore, ordering of the stray fields over the entire array helps to suppress dissipation and enhance commensurability effects increasing the number of dissipation minima.Comment: 16 pages including 4 figures; accepted in Applied Physics Letter

Active vibration damping of the Space Shuttle remote manipulator system

The feasibility of providing active damping augmentation of the Space Shuttle Remote Manipulator System (RMS) following normal payload handling operations is investigated. The approach used in the analysis is described, and the results for both linear and nonlinear performance analysis of candidate laws are presented, demonstrating that significant improvement in the RMS dynamic response can be achieved through active control using measured RMS tip acceleration data for feedback