The nature of X-ray spectral variability in Seyfert Galaxies

We use a model-independent technique to investigate the nature of the 2-15 keV X-ray spectral variability in four Seyfert galaxies and distinguish between spectral pivoting and the two-component model for spectral variability. Our analysis reveals conclusively that the softening of the X-ray continuum with increasing flux in MCG -6-30-15 and NGC 3516 is a result of summing two spectral components: a soft varying component (SVC) with spectral shape independent of flux and a constant hard component (HCC). In contrast, the spectral variability in NGC 4051 can be well described by simple pivoting of one component, together with an additional hard constant component. The spectral variability model for NGC 5506 is ambiguous, due to the smaller range of fluxes sampled by the data. We investigate the shape of the hard spectral component in MCG -6-30-15 and find that it appears similar to a pure reflection spectrum, but requires a large reflected fraction (R>3). We briefly discuss physical interpretations of the different modes of spectral variability.Comment: Accepted for publication in MNRAS letter

War on Television: Lessons for and from the Golf War

One year on - from the weather and the sea you would never guess that anything had happened'. Such was Christopher Bellamy's recent observation from aboard HMS Sheffield for The Independent about the ecological condition of the waters of the Persian Gulf a year after Operation Desert Storm1 • Considering the high media profile afforded to oil-smeared cormorants on glooming Saudi beaches, to blazing Kuwaiti oil-wells and to what was portrayed at the time as an ecological disaster of almost apocalyptic proportions, such an observation merely highlights the degree to which television audiences worldwide were bombarded with propaganda during the GulfWarof 1991.One year on - from the weather and the sea you would never guess that anything had happened'. Such was Christopher Bellamy's recent observation from aboard HMS Sheffield for The Independent about the ecological condition of the waters of the Persian Gulf a year after Operation Desert Storm1 • Considering the high media profile afforded to oil-smeared cormorants on glooming Saudi beaches, to blazing Kuwaiti oil-wells and to what was portrayed at the time as an ecological disaster of almost apocalyptic proportions, such an observation merely highlights the degree to which television audiences worldwide were bombarded with propaganda during the GulfWarof 1991

Agricultural science policy

Technological advances developed through R&D have supplied the world with not only more food, but better food. This report looks at issues raised by this changing environment for agricultural productivity, agricultural R&D, and natural resource management.Agriculture and state ,

The Situational Context of Police Sexual Violence: Data and Policy Implications

The horrors of sexual crimes perpetrated by law enforcement officers are laid bare in this study of 669 cases of police sexual violence. Here, authors Philip Matthew Stinson, Robert W. Taylor, and John Liederbach identify three scenarios in which law enforcement officers inflict sexual violence upon their mostly-female victims: 1) “driving while female,” 2) child predation, and 3) involvement in the sex worker industry. Especially sobering is the fact that, as opposed to law enforcement doing its solemn duty to report criminality on the part of fellow police officers, “citizens rather than police initiated the detection of the crimes in almost all the cases, whether the context involved child predation (94.8%), driving while female (94.7%), or the sex worker industry (90.8%).” Rather than an anomaly, sexual predation on the part of police, along with the routine cover-ups that perpetuate these crimes, appears to be just one component of the “rotten barrel” that depicts a culture of police corruption

The Impact on the Ohio River Watershed by the United States Federal Government

poster abstractThis interactive timeline, which currently covers 1775 through the first quarter of 2014, takes accounts of water-related actions of the federal government and places them alongside water-related environmental events. Research drew together water use information within Acts of Congress, legal cases argued before the Supreme Court, actions undertaken by agencies within the Executive Department, and reports of pollution or flood incidents. This data was then charted using Tiki-Toki software into separate bands along the timeline with descriptions, images, and links to add depth of explanation. This juxtaposition reveals a story tracing human interaction along the Ohio River watershed since the American Revolution. In addition, the Tiki-Toki software makes the information available in multiple views through which different patterns emerge allowing future researchers to manipulate the timeline to more easily see connections with their own projects. Because of the data’s inclusiveness and ease of use, this timeline can provide a platform for comparison with the companion site of the Rivers of the Anthropocene study, the River Tyne. However, since the primary region of study in the United States is the Ohio River and its tributaries, only data applicable to this region specifically or all water in the United States generally was utilized. Because of the exclusiveness of the data, frequent gaps in events may risk being misinterpreted as a period of inactivity on the part of the federal government, though this is likely not the case; even apparent inactivity along the Ohio reveals much about human impact on the waterway systems

Off-Duty and Under Arrest: An Exploratory Study of the Arrests of Off-Duty Police Officers, 2005-2017

Presentation at the Annual Meeting of the Academy of Criminal Justice Sciences in National Harbor, MD, on March 17, 2023

The Low Quiescent X-Ray Luminosity of the Transient X-Ray Burster EXO 1747-214

We report on X-ray and optical observations of the X-ray burster EXO 1747-214. This source is an X-ray transient, and its only known outburst was observed in 1984-1985 by the EXOSAT satellite. We re-analyzed the EXOSAT data to derive the source position, column density, and a distance upper limit using its peak X-ray burst flux. We observed the EXO 1747-214 field in 2003 July with the Chandra X-ray Observatory to search for the quiescent counterpart. We found one possible candidate just outside the EXOSAT error circle, but we cannot rule out the possibility that the source is unrelated to EXO 1747-214. Our conclusion is that the upper limit on the unabsorbed 0.3-8 keV luminosity is L < 7E31 erg/s, making EXO 1747-214 one of the faintest neutron star transients in quiescence. We compare this luminosity upper limit to the quiescent luminosities of 19 neutron star and 14 black hole systems and discuss the results in the context of the differences between neutron stars and black holes. Based on the theory of deep crustal heating by Brown and coworkers, the luminosity implies an outburst recurrence time of >1300 yr unless some form of enhanced cooling occurs within the neutron star. The position of the possible X-ray counterpart is consistent with three blended optical/IR sources with R-magnitudes between 19.4 and 19.8 and J-magnitudes between 17.2 and 17.6. One of these sources could be the quiescent optical/IR counterpart of EXO 1747-214.Comment: 7 pages, accepted by the Astrophysical Journa