Effects of spin on high-energy radiation from accreting black holes

Observations of jets in X-ray binaries show a correlation between radio power and black hole spin. This correlation, if confirmed, points toward the idea that relativistic jets may be powered by the rotational energy of black holes. In order to examine this further, we perform general relativistic radiative transport calculations on magnetically arrested accretion flows, which are known to produce powerful jets via the Blandfordâ Znajek (BZ) mechanism. We find that the X-ray and γ-ray emission strongly depend on spin and inclination angle. Surprisingly, the high-energy power does not show the same dependence on spin as the BZ jet power, but instead can be understood as a redshift effect. In particular, photons observed perpendicular to the spin axis suffer little net redshift until originating from close to the horizon. Such observers see deeper into the hot, dense, highly magnetized inner disk region. This effect is largest for rapidly rotating black holes due to a combination of frame dragging and decreasing horizon radius. While the X-ray emission is dominated by the near horizon region, the near-infrared (NIR) radiation originates at larger radii. Therefore, the ratio of X-ray to NIR power is an observational signature of black hole spin.

Claude McKay and the transnational novel

This thesis considers the three works of fiction of the Jamaican author Claude McKay (1889-1948) as a coherent transnational trilogy which dramatises the semi-autobiographical complexities of diasporic exile and return in the period of the 1920s and 1930s. Chapter One explores McKay’s urban North American novel, Home to Harlem (1928). I suggest that we need to ‘reworld’ conceptions of McKay’s writing in order to release him from his canonical confinement in the Harlem Renaissance. Querying the problematics of the city space, of sexuality and of race as they emerge in the novel, this chapter considers McKay’s percipient understanding of the need to reconfigure diasporic identity beyond the limits set by American nationalism. Chapter Two engages with McKay’s novel of portside Marseilles, Banjo (1929), and considers the homosocial interactions of the vagabond collective. A comparison of North America and France as supposed exemplars of individual liberty highlights the unsuitability of nationalistic prerogatives to an internally diverse black diaspora. Paul Gilroy’s Black Atlantic construct provides a suggestive space in which to re-imagine the possibilities of affiliation in the port. The latter section of the chapter examines McKay’s particular influence on, and relationship, to the Négritude movement and Pan-African philosophies. Chapter Three focuses on McKay’s third novel, Banana Bottom (1933). I suggest here that the three novels comprise a coherent New World Trilogy comparable to Edward (Kamau) Brathwaite’s trilogy, The Arrivants. This chapter considers both the Caribbean and the transnational dimensions to McKay’s work.

A new world a new American foreign policy: the Carter administration, Nicaragua, and the legacy of the Vietnam War, 1977-1981

The impact of the Vietnam War conditioned the Carter administration’s response to the Nicaraguan revolution in ways that reduced US engagement with both sides of the conflict. It made the countries of Latin America counter the US approach and find their own solution to the crisis, and allowed Cuba to play a greater role in guiding the overthrow of Nicaraguan dictator Anastasio Somoza Debayle. This thesis re-evaluates Carter’s policy through the legacy of the Vietnam War, because US executive anxieties about military intervention, Congress’s increasing influence, and US public concerns about the nation’s global responsibilities, shaped the Carter approach to Nicaragua. Following a background chapter, the Carter administration’s policy towards Nicaragua is evaluated, before and after the fall of Somoza in July 1979. The extent of the Vietnam influence on US-Nicaraguan relations is developed by researching government documents on the formation of US policy, including material from the Jimmy Carter Library, the Library of Congress, the National Security Archive, the National Archives and Records Administration, and other government and media sources from the United Nations Archives, New York University, the New York Public Library, the Hoover Institution Archives, Tulane University and the Organization of American States. The thesis establishes that the Vietnam legacy played a key role in the Carter administration’s approach to Nicaragua. Before the overthrow of Somoza, the Carter administration limited their influence in Nicaragua because they felt there was no immediate threat from communism. The US feared that an active role in Nicaragua, without an established threat from Cuba or the Soviet Union, could jeopardise congressional support for other foreign policy goals deemed more important. The Carter administration, as a result, pursued a policy of non-intervention towards the Central American country. After the fall of Somoza, and the establishment of a new government with a left wing element represented by the Sandinistas, the Carter administration emphasised non-intervention in a military sense, but actively engaged with the new Nicaraguan leadership to contain the potential communist influence that could spread across Central America in the wake of the Nicaraguan revolution.

Diverse heritage: exploring literary identity in the American Southwest

Since the age of colonisation, the territory of New Mexico has been exposed to a diversity of cultural influence. Throughout recorded history various forces have battled for control of this territory, resulting in a continuous redefinition of its political, geographic and economic boundaries. Early representations of the Southwest have been defined as “strategies of negotiation” between Anglo, Hispanic and Native populations, strategies that are particularly evident in the territory of New Mexico. The contemporary identity of regions like northern New Mexico have destabilised the notion of what constitutes racial purity in regions which are defined by diversity. This thesis aims to evaluate the literary history of northern New Mexico in order to determine how exposure to a diversity of cultural influence has affected the region’s identity. An analysis of Anglo and Native writers from northern New Mexico will illustrate that these racial groups were influenced by the same geographic landscape. As such, their writing displays many characteristics unique to the region. In providing a comparative analysis of Native and Anglo authors from northern New Mexico, this thesis seeks to demonstrate commonalities of theme, structure and content. In doing so this research encourages a new perspective on New Mexico writing one which effectively de-centres contemporary notions of what the American canon should be.

The life history and ecology of black scabbardfish (Aphanopus carbo Lowe 1839) in the north-east Atlantic

The black scabbardfish is a deep water species that supports commercial fisheries across a large area of the NE Atlantic shelf. The life history of black scabbardfish is poorly understood and a major unresolved issue is population structure. In this study it was used a combination of methodologies to get further knowledge in the life history and population structure of A. carbo over its wide distribution range in the Northeast Atlantic. The new knowledge acquired during this study, will increase our ability to better manage this species in the NE Atlantic. It has been postulated that fish caught to the west of the British Isles are pre-adults that migrate further south (to Madeira) for spawning, implying a single panmictic population. In this study, specimens of Aphanopus carbo were sampled between September 2008 and May 2010 from two different areas: NW Scotland (French trawlers and deep water surveys) and Madeira Islands (longliners commercial landings). Geographical differences in reproductive state of scabbardfish were evident, supportive of a north-south migration theory. In the northern area, all specimens found were immature, while in Madeira all maturity stages were observed. In Madeira, spawning occurred during the fourth quarter, with peak maturity in October (males) and in November (females). The age of this species has proven difficult and has led to different and contradictory age and growth estimates. For this study, we used two reading interpretations to determine age and estimate the growth parameters. To the west of the British Isles, specimens reached a lower maximum age and had a higher growth rate than those caught off Madeira. These differences are consistent with the theory of a single population of black scabbardfish in the NE Atlantic, highly segregate, with smaller, immature and younger fish caught to the west of the British Isles and bigger and mature caught in Madeira Islands. The feeding ecology showed strong evidence that the diet of black scabbardfish is associated with the spawning migration of blue whiting, which may support a northerly feeding migration theory for black scabbardfish. The stable isotope analyses in the muscle of black scabbardfish identified that black scabbardfish feeds on species with epipelagic and benthopelagic affinities. Comparison with stable isotope analysis in Madeira samples indicated that black scabbardfish feed at a similar trophic level and has the same trophic niche width in both areas, assuming similar baseline isotope compositions. Otolith stable isotopes (oxygen - δ18O and nitrogen - δ15N) analyses were used as a tool to clarify migratory behaviour. Otolith isotope ratios can provide insight into whether adults caught around Madeira fed in an isotopically depleted northerly ecosystem (NW Scotland) during their pre-adult period and then migrate towards south to spawn. Overall, the results support a south-north migration of pre adult fish from spawning areas around Madeira and a north-south migration from the west of Scotland to the spawning areas. Given its life cycle there is an urgent need that the management process recognizes the existence of a continuous widely distributed stock of black scabbardfish between the west of the British Isles and Madeira. The results highlight large scale dispersal in this species which needs to be treated as a highly migratory species and be managed as a single population.

Redefining military memorials and commemoration and how they have changed since the 19th century with a focus on Anglo-American practice

This thesis is a study of military memorials and commemoration with a focus on Anglo-American practice. The main question is: How has history defined military memorials and commemoration and how have they changed since the 19th century. In an effort to resolve this, the work examines both historic and contemporary forms of memorials and commemoration and establishes that remembrance in sites of collective memory has been influenced by politics, conflicts and religion. Much has been written since the Great War about remembrance and memorialization; however, there is no common lexicon throughout the literature. In order to better explain and understand this complex subject, the work includes an up-to-date literature review and for the first time, terminologies are properly explained and defined. Particular attention is placed on recognizing important military legacies, being familiar with spiritual influences and identifying classic and new signs of remembrance. The thesis contends that commemoration is composed of three key principles – recognition, respect and reflection – that are intractably linked to the fabric of memorials. It also argues that it is time for the study of memorials to come of age and proposes Memorialogy as an interdisciplinary field of study of memorials and associated commemorative practices. Moreover, a more modern, adaptive, General Classification System is presented as a means of identifying and re-defining memorials according to certain groups, types and forms. Lastly, this thesis examines how peacekeeping and peace support operations are being memorialized and how the American tragic events of 11 September 2001 and the war in Afghanistan have forever changed the nature of memorials and commemoration within Canada and elsewhere. This work goes beyond what has been studied and written about over the last century and provides a deeper level of analysis and a fresh approach to understanding the field of Memorialogy.

“Something isn’t right here”: American exceptionalism and the creative nonfiction of the Vietnam War

In this thesis, I argue that few attempts were as effective in correcting the exceptionalist ethos of the United States than the creative nonfiction written by the veterans and journalists of the Vietnam War. Using critical works on creative nonfiction, I identify the characteristics of the genre that allowed Paul John Eakin to call it ‘a special kind of fiction.’ I summarise a brief history of creative nonfiction to demonstrate how it became a distinctly American form despite its Old World origins. I then claim that it was the genre most suited to the kind of ideological transformation that many hoped to instigate in U.S. society in the aftermath of Vietnam. Following this, the study explores how this “new” myth-making process occurred. I use Tim O’Brien’s If I Die in a Combat Zone and Philip Caputo’s A Rumor of War to illustrate how autobiography/memoir was able to demonstrate the detrimental effect that America’s exceptionalist ideology was having on its population. Utilising narrative and autobiographical theory, I contend that these accounts represented a collective voice which spoke for all Americans in the years after Vietnam. Using Neil Sheehan’s A Bright Shining Lie and C.D.B. Bryan’s Friendly Fire, I illustrate how literary journalism highlighted the hubris of the American government. I contend that while poiesis is an integral attribute of creative nonfiction, by the inclusion of extraneous bibliographic material, authors of the genre could also be seen as creating a literary context predisposing the reader towards an empirical interpretation of the events documented within. Finally, I claim that oral histories were in their essence a synthesis of “everyman” experiences very much in keeping with the American zeitgeist of the early Eighties. Focussing solely on Al Santoli’s Everything We Had, I demonstrate how such polyphonic narratives personalised the history of the Vietnam War.