AGN Feedback models: Correlations with star formation and observational implications of time evolution

We examine the correlation between the star formation rate (SFR) and black hole accretion rate (BHAR) across a suite of different AGN feedback models, using the time evolution of a merger simulation. By considering three different stages of evolution, and a distinction between the nuclear and outer regions of star formation, we consider 63 different cases. Despite many of the feedback models fitting the M-\sigma\ relationship well, there are often distinct differences in the SFR-BHAR correlations, with close to linear trends only being present after the merger. Some of the models also show evolution in the SFR-BHAR parameter space that is at times directly across the long-term averaged SFR-BHAR correlation. This suggests that the observational SFR-BHAR correlation found for ensembles of galaxies is an approximate statistical trend, as suggested by Hickox et al. Decomposing the SFR into nuclear and outer components also highlights notable differences between models and there is only modest agreement with observational studies examining this in Seyfert galaxies. For the fraction of the black hole mass growth from the merger event relative to the final black hole mass, we find as much as a factor of three variation among models. This also translates into a similar variation in the post-starburst black hole mass growth. Overall, we find that while qualitative features are often similar amongst models, precise quantitative analysis shows there can be quite distinct differences.Comment: Accepted to MNRAS. Comments welcom

Unraveling the International Law of Colonialism: Lessons From Australia and the United States

In the 1823 decision of Johnson v. M’Intosh, Chief Justice John Marshall formulated the international law of colonialism. Known as the Doctrine of Discovery, Marshall’s opinion drew on the practices of European nations during the Age of Exploration to legitimize European acquisition of territory owned and occupied by Indigenous peoples. Two centuries later, Johnson—and the international law of colonialism—remains good law throughout the world. In this Article we examine how the Doctrine of Discovery was adapted and applied in Australia and the United States. As Indigenous peoples continue to press for a re-examination of their relationships with governments, we also consider whether and how the international law of colonialism has been mitigated or unraveled in these two countries. While we find that the Doctrine lingers, close examination provides several important lessons for all Indigenous nations and governments burdened by colonization

Final Report to the Coastal Erosion Abatement Commission, Commonwealth of Virginia concerning the inventory of sand supplies in the southern Chesapeake Bay

This final report to the Coastal Erosion Abatement Commission concerning the inventory of sand supplies in the southern portion of Chesapeake Bay is a continuation of the work reported on in September 1981 (Byrne et al). The report includes technical appendices in addition to the general text

Report to the Coastal Erosion Abatement Commission Commonwealth of Virginia concerning the Inventory of Sand Supplies in the Southern Chesapeake Bay

In its report to the Governor and the General Assembly of Virginia (Senate Document No. 4, Commonwealth of Virginia, 1979), the Coastal Erosion Abatement Commission found that there is a need to locate sources of sand supplies for rebuilding public beaches. Certain bottom areas in the lower Chesapeake Bay should be studied as possible sources of sand supply for public beaches. And toward that end, the Commission recommended that The School of Marine Science, Virginia Institute of Marine Science, College of William and Mary, study and analyze possible sources of sand supply in the lower Chesapeake Bay and vicinity for rebuilding public beaches. This report describes the investigations undertaken during the first year of the appropriation, July 1980 through June 1981

AGN feedback models: correlations with star formation and observational implications of time evolution

We examine the correlation between the star formation rate (SFR) and black hole accretion rate (BHAR) across a suite of different active galactic nuclei (AGN) feedback models, using the time evolution of a merger simulation. By considering three different stages of evolution, and a distinction between the nuclear and outer regions of star formation, we consider 63 different cases. Despite many of the feedback models fitting the M-σ relationship well, there are often distinct differences in the SFR-BHAR correlations, with close to linear trends only being present after the merger. Some of the models also show evolution in the SFR-BHAR parameter space that is at times directly across the long-term averaged SFR-BHAR correlation. This suggests that the observational SFR-BHAR correlation found for ensembles of galaxies is an approximate statistical trend, as suggested by Hickox etal. Decomposing the SFR into nuclear and outer components also highlights notable differences between models and there is only modest agreement with observational studies examining this in Seyfert galaxies. For the fraction of the black hole mass growth from the merger event relative to the final black hole mass, we find as much as a factor of 3 variation among models. This also translates into a similar variation in the post-starburst black hole mass growth. Overall, we find that while qualitative features are often similar amongst models, precise quantitative analysis shows there can be quite distinct difference

Alternative model for the administration and analysis of research-based assessments

Research-based assessments represent a valuable tool for both instructors and researchers interested in improving undergraduate physics education. However, the historical model for disseminating and propagating conceptual and attitudinal assessments developed by the physics education research (PER) community has not resulted in widespread adoption of these assessments within the broader community of physics instructors. Within this historical model, assessment developers create high quality, validated assessments, make them available for a wide range of instructors to use, and provide minimal (if any) support to assist with administration or analysis of the results. Here, we present and discuss an alternative model for assessment dissemination, which is characterized by centralized data collection and analysis. This model provides a greater degree of support for both researchers and instructors in order to more explicitly support adoption of research-based assessments. Specifically, we describe our experiences developing a centralized, automated system for an attitudinal assessment we previously created to examine students' epistemologies and expectations about experimental physics. This system provides a proof-of-concept that we use to discuss the advantages associated with centralized administration and data collection for research-based assessments in PER. We also discuss the challenges that we encountered while developing, maintaining, and automating this system. Ultimately, we argue that centralized administration and data collection for standardized assessments is a viable and potentially advantageous alternative to the default model characterized by decentralized administration and analysis. Moreover, with the help of online administration and automation, this model can support the long-term sustainability of centralized assessment systems.Comment: 7 pages, 1 figure, accepted in Phys. Rev. PE

Shoreline Erosion in the Commonwealth of Virginia: Problems, Practices, and Possibilities

This report, Shoreline Erosion in the Commonwealth of Virginia: Problems, Practices, and Possibilities, is a report on the physical, legal, and economic aspects of shoreline erosion in Virginia. Although erosion is a physical process, it generally is not perceived as a problem until it has an economic impact on either an individual, community, or resource. As management of the impacts of erosion involves land use, economic, and legal issues as well as a technical assessment of the problem, an interdisciplinary approach was required. Authors Byrne and Hobbs are physical scientists with experience and interest in the workings of the shoreline. Theberge is a lawyer specializing in marine affairs. Kerns, Langeland, and Scheid are resource economists and environmental planners; and Barber and Olthof are land use planners. The division of responsibilities followed the obvious lines. The physical scientists described the problem and its causes and provided the technical analysis of the shoreline. The economists explored the costs of erosion and of combating erosion and , .. developed the economic decision framework. The planners considered the institutional arrangements and policies necessary for the rational treatment of erosion; and the legal experts researched the existing body of law pertaining to shoreline erosion. The four groups functioned as a team with continuous interaction and discussion among all participants