Non-integrality of some Steinberg modules

We prove that the Steinberg module of the special linear group of a quadratic imaginary number ring which is not Euclidean is not generated by integral apartments. Assuming the generalized Riemann hypothesis, this shows that the Steinberg module of a number ring is generated by integral apartments if and only if the ring is Euclidean. We also construct new cohomology classes in the top dimensional cohomology group of the special linear group of some quadratic imaginary number rings.Comment: 17 pages. To appear in Journal of Topolog

In the shadow of the Gulag : worker discipline under Stalin

Highlights: • The Gulag had incentive effects on Soviet labour akin to unemployment in the West. • Stalin’s use of imprisonment for shirking-type behaviour and terror is documented. • An efficiency wage model shows how the threat of prison raises investible surplus. • It helps explain use of monitors, promises of a better future and harsh punishment. • But random incarceration, used for political purposes, raises the efficiency wage. An ‘efficiency wage’ model developed for Western economies is reinterpreted in the context of Stalin’s Russia, with imprisonment – not unemployment – acting as a ‘worker discipline device’. The threat of imprisonment allows the state to pay a lower wage outside the Gulag than otherwise, thereby raising the “surplus” left over for investment: this externality provides a reason for coercion over and above the direct productivity of those in custody. Just how credible the threat of imprisonment was under Stalin is documented using archival data now available; but the enormous scale of random imprisonment involved is, we argue, attributable not to economic factors but to Stalin’s insecurity in the absence of a legitimate process for succession. We develop a model of demand and supply for industrial labour in such a command economy. To get more resources for investment or war, the state depresses the level of real wages; to avoid incentive problems in the wider economy, the harshness of prison conditions can be intensified. This is the logic of coercion we analyse

The Specific Globular Cluster Frequencies of Dwarf Elliptical Galaxies from the Hubble Space Telescope

The specific globular cluster frequencies (S_N) for 24 dwarf elliptical (dE) galaxies in the Virgo and Fornax Clusters and the Leo Group imaged with the Hubble Space Telescope are presented. Combining all available data, we find that for nucleated dEs --- which are spatially distributed like giant ellipticals in galaxy clusters --- S_N(dE,N)=6.5 +- 1.2 and S_N increases with M_V, while for non-nucleated dEs --- which are distributed like late-type galaxies --- S_N(dE,noN)=3.1 +- 0.5 and there is little or no trend with M_V. The S_N values for dE galaxies are thus on average significantly higher than those for late-type galaxies, which have S_N < 1. This suggests that dE galaxies are more akin to giant Es than to late-type galaxies. If there are dormant or stripped irregulars hiding among the dE population, they are likely to be among the non-nucleated dEs. Furthermore, the similarities in the properties of the globular clusters and in the spatial distributions of dE,Ns and giant Es suggest that neither galaxy mass or galaxy metallicity is responsible for high values of S_N. Instead, most metal-poor GCs may have formed in dwarf-sized fragments that merged into larger galaxies.Comment: 12 pages (uses aaspp4.sty), 2 figures, 1 table, to appear in the Astrophysical Journa

A study of the personality types of Presidential Scholars at the University of Northern Iowa

As a Presidential Scholar, became interested in how those people who were awaded the scholarship differed in their personality types from those equally intelligent and involved people who did not. Thus, I decided to compare the personality types of the University of Northern Iowa Presidential Scholars to those members of Omicron Delta Kappa, which is the highest academic honorary society on campus. I chose to compare Presidential Scholars to ODK members because the ODK society emphasizes many of the same qualities as the Presidential Scholars Program: academics, leadership, and service. To become a member of ODK, a student must have at least a 3.3 grade point average and be involved in a wide variety of extracurricular activities. However, for the purposes of this experiment, I chose to involve only those students with a 3.5 grade point average or higher

On the generalized Bykovskii presentation of Steinberg modules

We study presentations of the virtual dualizing modules of special linear groups of number rings, the Steinberg modules. Bykovskii gave a presentation for the Steinberg modules of the integers, and our main result is a generalization of this presentation to the Gaussian integers and the Eisenstein integers. We also show that this generalization does not give a presentation for the Steinberg modules of several Euclidean number rings.Comment: Minor revisions based on referee's comments. Accepted for publication at IMR

Dynamical Friction in dE Globular Cluster Systems

The dynamical friction timescale for globular clusters to sink to the center of a dwarf elliptical galaxy (dE) is significantly less than a Hubble time if the halos have King-model or isothermal profiles and the globular clusters formed with the same radial density profile as the underlying stellar population. We examine the summed radial distribution of the entire globular cluster systems and the bright globular cluster candidates in 51 Virgo and Fornax Cluster dEs for evidence of dynamical friction processes. We find that the summed distribution of the entire globular cluster population closely follows the exponential profile of the underlying stellar population. However, there is a deficit of bright clusters within the central regions of dEs (excluding the nuclei), perhaps due to the orbital decay of these massive clusters into the dE cores. We also predict the magnitude of each dE's nucleus assuming the nuclei form via dynamical friction. The observed trend of decreasing nuclear luminosity with decreasing dE luminosity is much stronger than predicted if the nuclei formed via simple dynamical friction processes. We find that the bright dE nuclei could have been formed from the merger of orbitally decayed massive clusters, but the faint nuclei are several magnitudes fainter than expected. These faint nuclei are found primarily in M_V > -14 dEs which have high globular cluster specific frequencies and extended globular cluster systems. In these galaxies, supernovae-driven winds, high central dark matter densities, extended dark matter halos, the formation of new star clusters, or tidal interactions may act to prevent dynamical friction from collapsing the entire globular cluster population into a single bright nucleus.Comment: 15 pages, 2 tables, 7 figures; to appear in the Astrophysical Journal, April 20, 200

Early Detection Rapid Response Program Targets New Noxious Weed Species in Washington State

Early detection, rapid response is a critical component of invasive plant management. It can be challenging, however, to detect new invaders before they become established if landowners cannot identify species of concern. In order to increase awareness, eye-catching postcards were developed in Washington State as part of a noxious weed educational campaign. Plant identification, potential impacts, and current distributions are provided in a simple format for easy information consumption. Postcards are distributed across the state at various venues, thereby increasing the general public\u27s exposure to little known but high risk species