Efficient and Reasonable Object-Oriented Concurrency

Making threaded programs safe and easy to reason about is one of the chief difficulties in modern programming. This work provides an efficient execution model for SCOOP, a concurrency approach that provides not only data race freedom but also pre/postcondition reasoning guarantees between threads. The extensions we propose influence both the underlying semantics to increase the amount of concurrent execution that is possible, exclude certain classes of deadlocks, and enable greater performance. These extensions are used as the basis an efficient runtime and optimization pass that improve performance 15x over a baseline implementation. This new implementation of SCOOP is also 2x faster than other well-known safe concurrent languages. The measurements are based on both coordination-intensive and data-manipulation-intensive benchmarks designed to offer a mixture of workloads.Comment: Proceedings of the 10th Joint Meeting of the European Software Engineering Conference and the ACM SIGSOFT Symposium on the Foundations of Software Engineering (ESEC/FSE '15). ACM, 201

Impacts of Urbanization on Base Flow and Recharge Rates, Northeastern Illinois: Summary of Year 1 Activities

During year one of a two-year project to investigate the impacts of urbanization on base flow and ground-water recharge rates in northeastern Illinois, three gaged watersheds in urbanized areas of northeastern Illinois, and one watershed located in rural northwestern Illinois, have been selected for study. The gages have a common period of record extending from October 1952 through the present, a period during which the northeastern Illinois watersheds underwent substantial urbanization. Mean daily discharge data from the gages have been analyzed using an automated hydrograph separation technique, and monthly estimates of mean total discharge, base flow, and direct runoff have been calculated. Spearman rank correlation coefficients indicate a stronger correlation between precipitation and total discharge, base flow, and direct runoff in the northeastern Illinois watersheds than in the rural watershed. Smoothed time-series plots of total discharge, base flow, and direct runoff in the urban watersheds are less consistent with precipitation than similar plots constructed from the rural watershed data. The trends indicate that rates of direct runoff have overtaken rates of base flow in two of the three northeastern Illinois watersheds, but in one of these watersheds, this relationship probably reflects the cessation of effluent discharges to the stream. In general, double-mass curve analysis suggests that, relative to the rural watershed, base flow in the urban watersheds has proportionally decreased, and direct runoff has proportionally increased. The trends suggested by the smoothed time-series plots and the double-mass curves are consistent with a conceptual model of the northeastern Illinois watersheds in which sewering and impervious surfaces have reduced infiltration, and thence ground-water recharge and base flow, in the watersheds.Ope

Primordial Gravitational Waves and Cosmology

The observation of primordial gravitational waves could provide a new and unique window on the earliest moments in the history of the universe, and on possible new physics at energies many orders of magnitude beyond those accessible at particle accelerators. Such waves might be detectable soon in current or planned satellite experiments that will probe for characteristic imprints in the polarization of the cosmic microwave background (CMB), or later with direct space-based interferometers. A positive detection could provide definitive evidence for Inflation in the early universe, and would constrain new physics from the Grand Unification scale to the Planck scale.Comment: 12 pages. 4 figure

Giving Up Density as an approach to identify a difference in foraging behavior between native and invasive crayfish species

Placed third place at the CFAES Undergraduate Research ForumInvasive species are often thought to displace native species by being superior competitors through aggression and resource exploitation. In freshwater ecosystems, invasive crayfish have been frequently shown to displace native crayfish by outcompeting them for food resources. Here, we tested the hypothesis that the displacement of native crayfish, Orconectes sanbornii, by invasive crayfish, Orconectes rusticus, in Ohio streams may be due to superior foraging behavior of the invader. We also examined whether foraging behavior changed in the presence of a model fish predator. We ran a lab experiment where we used depletable food patches to compare the foraging behavior of native O. sanbornii and invasive and native populations of O. rusticus under high, low or no predation risk. The amount of food remaining in a patch after approximately a 24-hour period was used as an indication of giving up density (GUD) to measure crayfish foraging behavior under predation risk. Results indicated that there was no effect of predation risk on the GUD of either species (F 2,80 = 0.147, p = 0.86). However, native O. sanbornii left lower GUDs on average than either native or invasive populations of O. rusticus (p = 0.003, p = 0.026, respectively). This suggests that the native O. sanbornii is a more active forager than either a native or invasive population of O. rusticus. This suggests that O. rusticus might not be displacing O. sanbornii through exploitative competition but rather an unidentified mechanism. Gaining a better understanding and being able to better identify the mechanisms of species invasions can lead to better and more effective management of invasive species in the future.No embargoAcademic Major: Environmental Scienc

Mother Nature Needs Her SOX: Reviewing the Impetus and Goals of the Increased Financial Regulations of the Sarbanes-Oxley Act and How They Parallel the Needs of Today\u27s Environmental Protection Agency

As climate change and natural disasters appear to be increasingly prevalent across the United States, the question of how to respond to these threats looms large. Arguably, the Environmental Protection Agency (“EPA”) represents the tip of that responding spear. The agency, literally dedicated to protecting the environment, is positioned to drive industry environmental standards, set sustainable metrics, and even determine thresholds for habitable life. Looks can be deceiving, though. This Note examines the current state of the EPA, and the minimal effect it currently has on penalizing and deterring industry environmental degradation. It specifically focuses on a number of high-profile use cases of industry pollution, and the EPA’s response. Based on the apparent impotence of those responses, this Note then draws a direct parallel to the Securities and Exchange Commission (“SEC”) during the late nineties and early aughts, before the Sarbanes-Oxley act was passed. The corporate incentives of violating the EPA standards today directly parallel the incentives of businesses committing securities fraud back then. In short, there lacked a sufficient deterrent to counterbalance the incentives of increasing shareholder value through any means (even illegal ones). After the financial world was rocked with the repeated scandals of corporations like Enron, Worldcom, Tyco, etc., Congress responded by passing the Sarbanes-Oxley Act. The Act has three key objectives that resonate with today’s EPA: 1) clearer accountability; 2) expanded criminal liability; and 3) enhanced criminal penalties. The Sarbanes-Oxley Act worked because it drove accountability into the executive boardroom. The final piece of this Note replicates the model of Sarbanes- Oxley and examines the implications of a similar act in the context of the EPA through the same use cases detailed above. While the Sarbanes- Oxley Act was directed to protecting shareholder value, the EPA equivalent would have an even broader mandate, protecting the world itself