Modular symbols and Hecke operators

We survey techniques to compute the action of the Hecke operators on the cohomology of arithmetic groups. These techniques can be seen as generalizations in different directions of the classical modular symbol algorithm, due to Manin and Ash-Rudolph. Most of the work is contained in papers of the author and the author with Mark McConnell. Some results are unpublished work of Mark McConnell and Robert MacPherson.Comment: 11 pp, 2 figures, uses psfrag.st

Monte Carlo simulations of electron lateral distributions in the core region of 10(13) - 10(16) eV air showers

This paper contains details of computer models of shower development which have been used to investigate the experimental data on shower cores observed in the Leeds 35 sq m and Sacramento Peak (New Mexico) 20 sq m arrays of current limited spark (discharge) chambers. The simulations include predictions for primaries ranging from protons to iron nuclei (with heavy nuclei treated using both superposition and fragmentation models)

Particle distributions in approximately 10(13) - 10(16) eV air shower cores at mountain altitude and comparison with Monte Carlo simulations

Photographs of 521 shower cores in an array of current-limited spark (discharge) chambers at Sacramento Peak (2900m above sea level, 730 g /sq cm.), New Mexico, U.S.A., have been analyzed and the results compared with similar data from Leeds (80m above sea level, 1020 g sq cm.). It was found that the central density differential spectrum is consistent with a power law index of -2 up to approx. 1500/sq m where it steepens, and that shower cores become flatter on average with increasing size. Scaling model predictions for proton primaries with a approx E sup -2.71 energy spectrum account well for the altitude dependence of the data at lower densities. However, deviations at higher densities indicate a change in hadron interaction characteristics between approx few x 10 to the 14th power and 10 to the 15th power eV primary energy causing particles close to the shower axis to be spread further out

Comparison of simulation results with sea-level experimental data on 10(14) - 10(16) air shower cores

Simulation predictions for the Leeds 35 sq m horizontal discharge chamber array for proton primaries with a approx. E sup 2.7 spectrum extrapolated from balloon data to 10 to the 16th power eV give power law rho (r)-spectra with constant slope approx. -2 consistent with the experimental data up to the point at which they steepen but overshooting them at higher densities, and at high shower sizes predicted cores which are significantly steeper than those observed. Further comparisons with results for heavy nuclei primaries (up to A = 56) point to the inadequacy of changes in primary composition to account for the observed density spectra and core flattening, and the shower size spectrum together, and point, therefore, to the failure of the scaling interaction model at approx. 10 to the 15th power eV primary energy

Performance evaluation of channel estimation techniques for a mobile fourth generation wide area OFDM system

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Whose Money, Whose Time? A Nonparametric Approach to Modeling Time Spent on Housework

We argue that earlier quantitative research on the relationship between heterosexual partners’ earnings and time spent on housework has two basic flaws. First, it has focused on the effects of women’s shares of couples’ total earnings on their housework, and has not considered the simpler possibility of an association between women’s absolute earnings and housework. Consequently it has relied on unsupported theoretical restrictions in the modeling. We adopt a flexible, nonparametric approach that does not impose the polynomial specifications on the data that characterize the two dominant models of the relationship between earnings and housework, the “economic exchange” and “gender display” hypotheses. Our nonparametric model allows the relationships among earnings shares, earnings, and time spent on housework to emerge from the data. A second problem with earlier studies is that they have tended to draw uniform inferences across the range of data, including regions where the data are sparse. This has led to interpretations of parametric curves that are driven by these thinly populated regions, and that may not be robust across the data. By contrast, our study explicitly assesses the reliability of results obtained in such regions. Our results provide support for an alternative model that emphasizes the importance of partners’ own earnings for their housework, especially in the case of women. Women’s own earnings are negatively associated with their housework hours, independently of their partners’ earnings and their shares of couples’ total earnings, which do not matter.housework, household economics, nonparametric regression, bargaining, gender

Measuring Corporate Environmental Justice Performance

Measures of corporate environmental justice performance can be a valuable tool in efforts to promote corporate social responsibility and to document systematic patterns of environmental injustice. This paper develops such a measure based on the extent to which toxic air emissions from industrial facilities disproportionately impact racial and ethnic minorities and low-income people. Applying the measure to 100 major corporate air polluters in the United States, we find wide variation in the extent of disproportional exposures. In a number of cases, minorities bear more than half of the total human health impacts from the firm's industrial air pollution.Corporate social responsibility; corporate environmental performance; environmental justice; air pollution

Separate and Unequal: The Effect of Unequal Access to Employment-Based Health Insurance on Gay, Lesbian, and Bisexual People

Employers' standard practice of including legal spouses in health insurance is likely to place people in unmarried couples at a significant disadvantage for obtaining coverage. Data from married and unmarried couples in the Current Population Survey confirm that people with unmarried partners are two to three times more likely to lack health insurance than are people in married couples, even after controlling for factors that influence coverage. A requirement to provide the same benefits for partners as are provided to spouses would reduce the proportion of uninsured people in same-sex couples and different-sex couples by as much as 50%. We find no evidence of adverse selection. We predict that a typical employer offering domestic partner coverage will see a small increase in enrollment, ranging from 0.1% to 0.3% for same-sex partners and 1.3% to 2.1% for different-sex unmarried partners.health, health insurance, benefits, employment benefits, health disparities, domestic partners, minorities, discrimination, gender, sexuality, sexual orientation, gay, lesbian, marriage, same-sex couples