Changing Sources of Magma Generation Beneath Intra-Oceanic Islands Arcs: An Insight From the Juvenile Kohistan Island Arc, Pakistan Himalaya

The Kohistan arc, situated in the Pakistan Himalaya, is a Cretaceous intraoceanic island arc which was initiated during the northward movement of the Indian Plate. The arc was sutured to Asia at ca. 100 Ma. It was subsequently tilted northward when underplated by Indian continental crust during the early stages of India–Asia collision. Deep erosion of this tilted section provides a spectacular section through the whole arc sequence and offers a profound insight into the mechanisms of early stages of arc formation. Geochemical analysis and rare earth element modelling of basaltic sequences which date from the intraoceanic stages of arc development allow identification of three main magma source types in the mantle beneath the juvenile arc. The ‘E-type’ Kamila Amphibolites, with a MORB-type chemistry, form the intraoceanic basement to the arc. The ‘D-type’ Kamila Amphibolites are the earliest of the arc volcanic rocks. These were extracted from a primitive spinel-bearing mantle source, above a north-dipping subduction zone. The stratigraphically younger basalts of the Jaglot Group and Ghizar Formation of the Chalt Volcanic Group were derived from partial melting of a garnet-bearing source at greater depth. The Hunza Formation of the Chalt Volcanic Group contains the youngest mafic volcanic rocks of the intraoceanic arc. Although coeval with the Ghizar Formation of the Chalt Volcanic Group, they were generated by melting of a depleted, spinel-bearing mantle source rock and were erupted into a spatially and temporally restricted back-arc basin developed behind the volcanic front. The Chalt Volcanic Group was therefore formed from two different, adjacent, mantle source regions active at the same time. Results of REE modelling are consistent with models for intraoceanic arc formation in which the earliest volcanic rocks are derived from shallow level spinel-bearing peridotite, and later ones from a deeper garnet-bearing source. This is consistent with the melt region becoming deeper with time as subduction continues. A two-stage model is proposed for the back-arc basalts of the Hunza Formation in which a mantle source, depleted from a previous melting event, is underplated beneath the arc and later remelted during decompression as a consequence of extension and rifting of the arc

The role of the narrator in narrative inquiry in education: construction and co-construction in two case studies

This paper explores narratives as an effective means of capturing multiple identities of research participants in complex social environments in education research. In doing so, it explores the role of the narrator in two case studies in two modes of narrative inquiry. Both studies present narratives of young people, focusing on multiple identities which are influenced by a variety of cultural and sub-cultural contexts which the participants inhabit to varying degrees. In the first case study, the researcher is the narrator; in the second, it is the research participants. The paper uses the two case studies to discuss three challenging areas in narrative research: participant voice, contextual complexities and researcher positionality and how the researcher responds to these challenges through construction and co-construction of the narratives. The authors share their strategies for addressing these three challenges in relation to the role of the narrator

Playing on the boundaries: a childhood across cultural and geographical lines

This is not a conventional paper. It is a personal narrative. It is subjective not only to its author but to the child-self of the author. It is not a detached academic look at a personal history. In fact it could be described more as ‘archaeological’ than historical; an examination of what appears to be a random collection of fragments of a personal history, found in memory and artefacts of a childhood. The telling of the story is an attempt to understand the development and trajectory of an individual identity across geographical, cultural, and religious boundaries. It is not the whole story, but it gives the writer and the reader a few selected pieces of the full picture

A concept analysis of befriending

Aim. To report an analysis of the concept of Befriending. Background. Befriending is an intervention used in a range of nursing, health and social care settings to provide support for individuals who are socially isolated or lack social support. However, in many cases befriending and its impact remains poorly understood and under researched. Concept analysis provides clarification of the concept and basis for further research and development. Design. Concept analysis. Data sources. AMED, Psyc Articles, Psych Info, Medline, MedlinePlus, Social Science Index and CINHAL databases were searched for literature published between 1993–2013 using the search term Befriending. Methods. Walker and Avant’s method of concept analysis was chosen. This combined with insights from Risjord’s work produced a theoretical concept analysis which focused on the concept in peer reviewed academic literature. Results. There are currently several ways the mechanisms of befriending and its effects on individuals and communities are understood. It is possible however to identify key attributes which define the concept and differentiate it from related concepts, such as peer support and mentoring. Key attributes are that it is an organised intervention, involving the creation of an emotionally connected friendlike relationship, where there is a negotiation of power. Conclusion. This concept analysis has clarified current understandings and uses of befriending. It provides the basis for widening the focus of research into the effectiveness and impact of befriending on those who are befriended, those who befriend and the communities where befriending takes place

Delegation and supervision of health care assistants' work in the daily management of uncertain and the unexpected in clinical practice: invisible learning among newly qualified nurses.

The invisibility of nursing work has been discussed in the international literature but not in relation to learning clinical skills. Evans and Guile’s (2012) theory of recontextualisation is used to explore the ways in which invisible or unplanned and unrecognised learning takes place as newly qualified nurses learn to delegate to and supervise the work of the health care assistant. In the British context, delegation and supervision are thought of as skills which are learnt ‘on the job’. We suggest that learning ‘on-the-job’ is the invisible construction of knowledge in clinical practice and that delegation is a particularly telling area of nursing practice which illustrates invisible learning. Using an ethnographic case study approach in three hospital sites in England from 2011-2014, we undertook participant observation, interviews with newly qualified nurses, ward managers and health care assistants. We discuss the invisible ways newly qualified nurses learn in the practice environment and present the invisible steps to learning which encompass the embodied, affective and social, as much as the cognitive components to learning. We argue that there is a need for greater understanding of the ‘invisible learning’ which occurs as newly qualified nurses learn to delegate and supervise

Rule-based interactive assisted reinforcement learning

Reinforcement Learning (RL) has seen increasing interest over the past few years, partially owing to breakthroughs in the digestion and application of external information. The use of external information results in improved learning speeds and solutions to more complex domains. This thesis, a collection of five key contributions, demonstrates that comparable performance gains to existing Interactive Reinforcement Learning methods can be achieved using less data, sourced during operation, and without prior verifcation and validation of the information's integrity. First, this thesis introduces Assisted Reinforcement Learning (ARL), a collective term referring to RL methods that utilise external information to leverage the learning process, and provides a non-exhaustive review of current ARL methods. Second, two advice delivery methods common in ARL, evaluative and informative, are compared through human trials. The comparison highlights how human engagement, accuracy of advice, agent performance, and advice utility differ between the two methods. Third, this thesis introduces simulated users as a methodology for testing and comparing ARL methods. Simulated users enable testing and comparing of ARL systems without costly and time-consuming human trials. While not a replacement for well-designed human trials, simulated users offer a cheap and robust approach to ARL design and comparison. Fourth, the concept of persistence is introduced to Interactive Reinforcement Learning. The retention and reuse of advice maximises utility and can lead to improved performance and reduced human demand. Finally, this thesis presents rule-based interactive RL, an iterative method for providing advice to an agent. Existing interactive RL methods rely on constant human supervision and evaluation, requiring a substantial commitment from the advice-giver. Rule-based advice can be provided proactively and be generalised over the state-space while remaining flexible enough to handle potentially inaccurate or irrelevant information. Ultimately, the thesis contributions are validated empirically and clearly show that rule-based advice signicantly reduces human guidance requirements while improving agent performance.Doctor of Pholosoph

Memories of childhood in post-war Grimsby

This paper details the vivid memories of the author’s childhood in the fishing port of Grimsby, shortly after the Second World War. It was a time of shortages, overcrowding, improvisation and cannibalisation of anything that could be re-used. In time it became a period of reconstruction but not without its upheavals and difficulties. It begins in the ‘old town’ of workers’ small terrace houses, typically in a poor state of repair. Then it moves to the ‘new’ council estates. Similarly, the narrative also begins with a ‘Victorian’ technology of steam, coal and horses with very few petrol-engined vehicles and moves to the very beginnings of early consumer society. The principal analytic content of the paper concerns the status of what is clearly a ‘personal history’ – if that is not too great a contradiction – or as the author suggests: my story. The obvious ‘critical’ response – that it could have been otherwise – is contrasted against the suggestion that this story is a non-negotiable foundation of the author’s identity and that this ‘critical’ response is not appropriate. Some of the interdisciplinary options thrown up by this problem are considered

Optimisation of the PFC functional

In this thesis we develop and analyse gradient-fl ow type algorithms for minimising the Phase Field Crystal (PFC) functional. The PFC model was introduced by Elder et al [EKHG02] as a simple method for crystal simulation over long time-scales. The PFC model has been used to simulate many physical phenomena including liquid-solid transitions, grain boundaries, dislocations and stacking faults and is an area of active physics and numerical analysis research. We consider three continuous gradient fl ows for the PFC functional, the L2-, H-1- and H2-gradient fl ows. The H-1-gradient flow, known as the PFC equation, is the typical flow used for the PFC model. The L2-gradient flow is known as the Swift-Hohenberg equation. The H2-gradient ow appears to be a novel feature of this thesis and will motivate our development of a line search algorithm. We analyse two methods of time discretisation for our gradient fl ows. Firstly, we develop a steepest descent algorithm based on the H2-gradient fl ow. We further develop a convex-concave splitting of the PFC functional, recently proposed by Elsey and Wirth [EW13], to discretise the L2- and H-1-gradient flows. We are able to prove energy stability of both our steepest descent algorithm and the convex-concave splitting scheme of [EW13]. We then use the Lojasiewicz gradient inequality (first developed in [ Loj62]) to prove that all three schemes converge to equilibrium. For numerical simulations we undertake spatial discretisation of our schemes using Fourier spectral methods. We consider a number of implementation issues for our fully discrete algorithms including a striking issue that occurs when the number of spatial grid points is low. We then perform several numerical tests which indicate that our new steepest descent algorithm performs well compared with the schemes of [EW13] and even compared with a Newton type scheme (the trust region method)