Numerical modelling of slab breakoff and its magmatic effects

The process of slab breakoff following the collision of continental plates has been invoked to account for many magmatic observations in post -collisional areas. These interpretations are often based upon the results of kinematic modelling of slab breakoff, which find this process can induce a thermal perturbation in the overriding plate, possibly generating lithospheric melting. Such a process requires that breakoff occurs at depths shallower than the base of the overriding lithosphere. This thesis aims to investigate more thoroughly the magmatic effects that breakoff may have. 2D numerical experiments are conducted, which make use of a thermodynamic database to determine the generation of melts and (de)hydration processes that occur within a collisional environment. A systematic parametric study is designed, which investigates those factors which may have a significant control on the breakoff depth. The breakoff timing and resulting mantle flow patterns are also investigated, as these may affect the magmatic processes. The strength of the subducting continental lithosphere is found to have a key control on the breakoff depth, whilst the timing and flow are significantly dependent upon the mantle rheology. By investigating further those conditions which promote shallow breakoff, it is found that breakoff appears unable to induce any significant melting of the overriding mantle lithosphere. In most cases , breakoff localises deeper than the overriding plate, preventing melting. Even following very shallow breakoff, the rapid descent of the detached slab gives way to a subsequent cooling of the overriding plate. A more commonly observed feature is the melting of continental crust upon breakoff, which may be a more reliable indicator of the occurrence of breakoff than lithospheric melting. Despite this, post-collisional magmatic observations show a wide range of compositions, timings, and localities. It is unlikely that melting across a post-collisional area can be attributed to any one geodynamic process

A Few Good Men: Narratives of Racial Discrimination Impacting Male African American/Black Officers in the United States Marine Corps

In the United States of America (U.S.), institutional marginalization and racial discrimination remains an arguably difficult subject to understand, both conceptually and pragmatically. Regarding governmental sectors, U.S. Armed Forces are institutions where discrimination must be critically explored in an attempt to provide an understanding of the reality faced by those who actually serve. This study involved the examination into racism within a specific elite governmental sector that emphasizes a philosophy of a unified oneness of all its members. Using a phenomenological approach, the study delved into the actual impact of racism within the Marine Corps, on the lives of individual members of a historically marginalized populace, African American/Black. The research explored and analyzed the life stories of three male members of the aforementioned population group, hence seeking to answer the research question: How has Integrated Racial Diversity in the Armed Forces Impacted Experiences of Discrimination Antagonistic to Male African American/Black Marine Corps Officers as Members of a Population Historically Marginalized and Discriminated against in the United States of America? Theories incorporated in the research offered meaning to the experiences of the individual participants. Discoveries illustrated the necessity of adaptation by the individual in coping with the impact of racially charged hostilities in an environment supposedly operating with an objective of oneness of its members. Through the findings, a theory of socio-psycho-bio dissonance was developed by the researcher. This research provides recommendations on practical ways to transformatively address and seek probable resolution in conflict – institutionally

Project management in practice: Views from the Trenches

Software development has endured radical change with the introduction of agile methods for creating software solutions. This change has prompted new considerations of how software creation should be managed. While agile methods have changed software development processes, it would be premature to assume that has also induced modification in higher-level project management processes. Software development lifecycles (SDLC) and project management lifecycles (PLC), while associated, are not the same thing and it is still unclear to what degree the overarching project management tasks, tools or techniques must change or adapt to meet the needs of undertaking successful agile projects. This exploratory pilot study investigated agile methods used to manage software projects and was conducted via an online survey and restricted to a specific sample audience with significant project experience and with background in both traditional and agile development methods. The results indicate that traditional project management phases and techniques are adapted to fit with agile. However, as the discipline evolves the potential exists for a pure agile project management framework to surface -one that can be applied to better suit the needs of the management of agile projects as well as projects beyond the realm of software development

The work and thought of Hugh of Amiens (c. 1085-1164)

Throughout the course a long life in which he served as a cleric, a Cluniac monk, and an archbishop, Hugh of Amiens (c. 1085-1164) wrote a number of works including poems, biblical exegesis, anti-heretical polemics, and one of the early collections of systematic theology. This dissertation aims to provide an intellectual biography of Hugh which grants a better understanding not only of his motivations and ideals, but also some of those of the wider clerical and monastic world of the twelfth century. It examines each of Hugh's theological and literary compositions with their manuscript distribution, chronology, and contemporary setting, giving an in-depth exegesis of the texts including their concerns, sources of material, and their meaning within the context of their day. So too does it compare him with contemporaries who were writing similar works, from the compilers of sentences to biblical versifiers. Many themes surface in this work. One of these is the influence that both the scholastic and the monastic worlds had on Hugh. His writings show that he, along with many of his contemporaries, was secure in drawing inspiration from the contemplative spirit of the cloister as well as the methodical and disputatious endeavours of the schools. Another key theme is the extensive influence of St. Augustine, not just upon Hugh's thought, but also upon the thought of most of Hugh's contemporaries. The role of Hugh's works in the origin of systematic theology also emerges, as does their relation to events in the larger religious, social, and political scene, such as the rise of popular heresies and new religious movements, the condemnation of Gilbert de la Porree (c. 1076-1154), and the schism under Pope Alexander III (c. 1100-81). It concludes that Hugh was not only an intriguing individual, but also a representative of many of the important and widespread trends of his day

Review of alcohol and drug treatment for Aboriginal and Torres Strait Islander peoples

This review provides an overview of treatments for problem alcohol and other drug (AOD) use for Aboriginal and Torres Strait Islander people. It includes information on the available research and discusses core principles for providing treatment. The review outlines how effective mainstream treatment approaches can be adapted to be more suitable for Aboriginal and Torres Strait Islander ways of being or worldview. It also highlights that services, such as those offered by Aboriginal community controlled health organisations are in a unique position to offer culturally secure treatment approaches. The barriers to accessing treatment are discussed as well as recommendations for future strategic directions in service delivery such as collaboration and two-way learning. This review is part of a suite of knowledge exchange products that includes a summary, video, and factsheet

Handbook for Aboriginal Alcohol and Drug Work

The Handbook for Aboriginal Alcohol and Drug Work is a practical tool written for Aboriginal drug and alcohol workers, mental health workers and others working in this field. It offers a detailed look at alcohol and drug work from clinical, through to prevention, early intervention and harm reduction. This handbook is also likely to help people working to improve policy and those advocating for change. The idea for it came from workers all over Australia. They told us that they needed an easy to use handbook that can help them respond to the range of alcohol and drug issues they face every day. They also told us that such a book needs to take into account the complex challenges facing workers when helping clients, their families and, sometimes, whole communities

Combustion gas emissions spectra of Otto cycle engine operating on H₂, CO, and gasoline using a calibrated vidicon detector spectrometer

The capabilities of the Tektronix Model J2C/7J20 Rapid Scanning Spectrometer for the determination of molecular species resulting from Otto cycle combustion were experimentally investigated after a literature search of the subject area. Combustion of hydrogen-air, carbon monoxideair, and gasoline-air mixtures in the combustion chamber of a Cooperative Fuel Research engine was observed using a quartz window and glass fibre optic light path. Various fuel-air ratios were tested for each fuel. The experimental work indicated that the Tektronix unit was well adapted to monitoring the rapidly changing light emissions and for rapid searches of the spectrum for any spectral features cf interest. Only emissions from CO, CO₂ and H₂O were identified with certainty as the band spectra of these molecules masked emissions of ther species thermodynamically predicted to exist. An improved optical connection and a light gating system are suggested as means to improve the instrument's resolving power for this application

Numerical models of the magmatic processes induced by slab breakoff

After the onset of continental collision, magmatism often persists for tens of millions of years, albeit with a different composition, in reduced volumes, and with a more episodic nature and more widespread spatial distribution, compared to normal arc magmatism. Kinematic modelling studies have suggested that slab breakoff can account for this post-collisional magmatism through the formation of a slab window and subsequent heating of the overriding plate and decompression melting of upwelling asthenosphere, particularly if breakoff occurs at depths shallower than the overriding plate. To constrain the nature of any melting and the geodynamic conditions required, we numerically model the collision of two continental plates following a period of oceanic subduction. A thermodynamic database is used to determine the (de)hydration reactions and occurrence of melt throughout this process. We investigate melting conditions within a parameter space designed to generate a wide range of breakoff depths, timings and collisional styles. Under most circumstances, slab breakoff occurs deeper than the depth extent of the overriding plate; too deep to generate any decompressional melting of dry upwelling asthenosphere or thermal perturbation within the overriding plate. Even if slab breakoff is very shallow, the hot mantle inflow into the slab window is not sustained long enough to sufficiently heat the hydrated overriding plate to cause significant magmatism. Instead, for relatively fast, shallow breakoff we observe melting of asthenosphere above the detached slab through the release of water from the tip of the heating detached slab. Melting of the subducted continental crust during necking and breakoff is a more common feature and may be a more reliable indicator of the occurrence of breakoff. We suggest that magmatism from slab breakoff alone is unable to explain several of the characteristics of post-collisional magmatism, and that additional geodynamical processes need to be considered when interpreting magmatic observations