Processes of granite emplacement: NW Ireland and SE Brazil

This thesis is a study of some of the processes which operate at mid crustal levels (10- 20km) during the emplacement of granitoid magmas, with particular reference to the process of in-situ expansion and the association between magma emplacement and orogen evolution. A number of plutons were studied to assess this the Ardara pluton from Donegal, NW Ireland, together with the Atibaia, Morro Azul, Imbiricu and Itapeti plutons from the Rio Paraiba do Sul shear belt (RPSSB), Sao Paulo state, SE Brazil. The emplacement of the Ardara pluton has been the subject of studies by many authors since the 1950's. It has been interpreted as a diapir ascending along a thrust, a granite balloon which forcefully created more than 60% of its space and, most recently, as a set of nested diapirs which forcefully created only 30% of their own space. Field mapping together with the determination of finite strain within the pluton, shortening estimates, shear sense determinations, petrographic deformation fabrics and computer modelling indicates that: i) the pluton displays a concentrically increasing finite strain and it expanded in-situ from a central 'injection point', having possibly ascended along a shear zone-related conduit; ii) the country rocks partitioned intense strains into the 500m closest to the pluton, a deformation feature which is shown to be consistent with a power-law wallrock theology; Hi) earlier granite pulses and the country rock were 'shouldered aside' to the east and west, expansion of the pluton, which was preferentially in a northwards direction; iv) that the intrusion related shortening preserved within the wallrocks was approximately equivalent to the strain preserved within pluton and the space requirements for the pluton are essentially met by preserved forceful emplacement-related strains; and v) if the pluton magma is considered as having ascended through dyke-like conduits emplacement could occur in a minimum of ~4000yrs, whereas magma ascent as a Hot Stokes diapir would require hundreds of thousands to millions of years for complete emplacement. Finally, the Ardara pluton does not conform to any of the established criteria for diapir-like ascent of a magma body and the data demonstrate it to be a testable example of a pluton which expanded entirely in-situ. The Rio Paraiba do Sul shear belt (RPSSB) is a dextral transpressional segment of the Late Precambrian Brasiliano-Pan African orogenic belt. The studied plutons were emplaced in the latter stages of this orogen in close spatial association with one of the many northeast-southwest trending, sub-vertical, continental-scale shear zones. All the granites show a similar emplacement and deformation history despite their different petrographic features and isotopic ages. This history consists of an early shallowly dipping, low angle fabric, in the country rocks, associated with crustal thickening, the later development of dominantly dextral sub-vertical shear zones, followed by the emplacement of the studied plutons and finally overprinting by a pervasive dextral plane strain and late-stage discrete mylonitic shears. Field examination demonstrates that: i) each of the plutons preserves an internally homogeneous emplacement-related finite strain, weak magmatic fabric, magma sheets and weakly deformed wallrocks; ii) magmatic shear sense determinations and wallrock deformation fabrics indicate that, during emplacement, the RPSSB was extending (at least at the emplacement level) in an east-west direction creating sinistral dilatational pull-aparts along the major shear zones, into which granitic magma was preferentially emplaced; and Hi) within this generally extensional context there was a component of long axis perpendicular in-situ forceful expansion, this created no more than 20% of the width of any one granite. Applying a simple pull-apart extension model suggests that pluton emplacement was associated with approximately 40% regional extension sub-parallel to the former orogenic convergence direction. This emplacement, as a result of sheeting through dyke-like conduits, requires thousands of years, rather than the millions of years required for ascent and emplacement of a Hot Stokes diapir. Interpreting these results suggests that the intruded granitoids are associated with a mid-crustal component of orogen perpendicular extension I collapse during the latter stages of the Brasiliano orogeny. Such extension I collapse could have been initiated by: a cessation in continental convergence or; by the delamination of a thickened thermal boundary layer, a process which has been suggested to be the driving force behind orogenic collapse in younger orogenic belts. These examples demonstrate that: i) 'forceful' balloon-like emplacement of granitic magma can occur; ii) there are very close inter-relationships between granite emplacement and orogenic dynamics; and Hi) that 'space' for granitoid magma can be created by a combination of forceful and dilatational and fault-related mechanisms

Findings of the International Subarachnoid Aneurysm Trial and the National Study of Subarachnoid Haemorrhage in context.

Concern has been expressed about the applicability of the findings of the International Subarachnoid Aneurysm Trial (ISAT) with respect to the relative effects on outcome of coiling and clipping. It has been suggested that the findings of the National Study of Subarachnoid Haemorrhage may have greater relevance for neurosurgical practice. The objective of this paper was to interpret the findings of these two studies in the context of differences in their study populations, design, execution and analysis. Because of differences in design and analysis, the findings of the two studies are not directly comparable. The ISAT analysed all randomized patients by intention-to-treat, including some who did not undergo a repair, and obtained the primary outcome for 99% of participants. The National Study only analysed participants who underwent clipping or coiling, according to the method of repair, and obtained the primary outcome for 91% of participants. Time to repair was also considered differently in the two studies. The comparison between coiling and clipping was susceptible to confounding in the National Study, but not in the ISAT. The two study populations differed to some extent, but inspection of these differences does not support the view that coiling was applied inappropriately in the National Study. Therefore, there are many reasons why the two studies estimated different sizes of effect. The possibility that there were real, systematic differences in practice between the ISAT and the National Study cannot be ruled out, but such explanations must be seen in the context of other explanations relating to chance, differences in design or analysis, or confounding

Profile: The Kilifi Health and Demographic Surveillance System (KHDSS).

The Kilifi Health and Demographic Surveillance System (KHDSS), located on the Indian Ocean coast of Kenya, was established in 2000 as a record of births, pregnancies, migration events and deaths and is maintained by 4-monthly household visits. The study area was selected to capture the majority of patients admitted to Kilifi District Hospital. The KHDSS has 260 000 residents and the hospital admits 4400 paediatric patients and 3400 adult patients per year. At the hospital, morbidity events are linked in real time by a computer search of the population register. Linked surveillance was extended to KHDSS vaccine clinics in 2008. KHDSS data have been used to define the incidence of hospital presentation with childhood infectious diseases (e.g. rotavirus diarrhoea, pneumococcal disease), to test the association between genetic risk factors (e.g. thalassaemia and sickle cell disease) and infectious diseases, to define the community prevalence of chronic diseases (e.g. epilepsy), to evaluate access to health care and to calculate the operational effectiveness of major public health interventions (e.g. conjugate Haemophilus influenzae type b vaccine). Rapport with residents is maintained through an active programme of community engagement. A system of collaborative engagement exists for sharing data on survival, morbidity, socio-economic status and vaccine coverage

Working with Concepts: The Role of Community in International Collaborative Biomedical Research

The importance of communities in strengthening the ethics of international collaborative research is increasingly highlighted, but there has been much debate about the meaning of the term ‘community’ and its specific normative contribution. We argue that ‘community’ is a contingent concept that plays an important normative role in research through the existence of morally significant interplay between notions of community and individuality. We draw on experience of community engagement in rural Kenya to illustrate two aspects of this interplay: (i) that taking individual informed consent seriously involves understanding and addressing the influence of communities in which individuals’ lives are embedded; (ii) that individual participation can generate risks and benefits for communities as part of the wider implications of research. We further argue that the contingent nature of a community means that defining boundaries is generally a normative process itself, with ethical implications. Community engagement supports the enactment of normative roles; building mutual understanding and trust between researchers and community members have been important goals in Kilifi, requiring a broad range of approaches. Ethical dilemmas are continuously generated as part of these engagement activities, including the risks of perverse outcomes related to existing social relations in communities and conditions of ‘half knowing’ intrinsic to processes of developing new understandings

Ward Round – A patient with multi-organ failure

No Abstract

Establishing the impact of powerful AGN on their host galaxies

Establishing the role of active galactic nuclei (AGN) during the formation of galaxies remains one of the greatest challenges of galaxy formation theory. Towards addressing this, we summarise our recent work investigating: (1) the physical drivers of ionised outflows and (2) observational signatures of the impact by jets/outflows on star formation and molecular gas content in AGN host galaxies. We confirm a connection between radio emission and extreme ionised gas kinematics in AGN hosts. Emission-line selected AGN are significantly more likely to exhibit ionised outflows (as traced by the [O III] emission line) if the projected linear extent of the radio emission is confined within the spectroscopic aperture. Follow-up high resolution radio observations and integral field spectroscopy of 10 luminous Type 2 AGN reveal moderate power, young (or frustrated) jets interacting with the interstellar medium. We find that these sources live in highly star forming and gas rich galaxies. Additionally, by combining ALMA-derived dust maps with integral field spectroscopy for eight host galaxies of z~2 X-ray AGN, we show that H-alpha emission is an unreliable tracer of star formation. For the five targets with ionised outflows we find no dramatic in-situ shut down of the star formation. Across both of these studies we find that if these AGN do have a negative impact upon their host galaxies, it must be happening on small (unresolved) spatial scales and/or an observable galaxy-wide impact has yet to occur.Comment: Invited Contribution to IAU Symposium 359 (T. Storchi-Bergmann, R. Overzier, W. Forman & R. Riffel, eds.

An investigation into the relationship between kinesiophobia and outcomes of a lower limb exercise programme in knee osteoarthritis

Osteoarthritis (OA) is one of the leading causes of pain and disability. Exercise has been recommended as a core treatment for OA. Exercise behaviour is an essential factor with kinesiophobia/fear of movement being a major clinical implication. Understanding exercise behaviour may provide a more comprehensive rehabilitation programme for individuals with knee osteoarthritis. Therefore, the purpose of the study was to investigate the relationship between kinesiophobia and outcomes of a lower limb exercise programme in knee osteoarthritis. Fifty-four individuals with clinical and/or radiographic knee OA (mean age 63.4 years (range 47-79); 50% female) completed a 4-week, 8-session lower limb exercise programme. Tampa scale of kinesiophobia (TSK), physical activity scale for the elderly (PASE), Knee injury and osteoarthritis outcome score (KOOS), Y balance test, 6-minute walk test (6MWT) and the 30-second chair stand test with an activPAL™ activity monitor were used with six standard physiotherapy questions asked to give the participants a voice during the research. Significant results from baseline to 6-weeks post programme were reported in kinesiophobia, Y balance test, KOOS pain, quality of life, activities of daily living, symptoms, sport and recreation, PASE, 6MWT and the 30-second chair stand test. Furthermore, significant results for 7-days of stepping and transitions, and for cadence banding 110-120 steps per minute. Average steps per day increased from 7,491 to 8,166. Our findings demonstrate that kinesiophobia and pain reduces after completing the exercise programme in participants with knee OA. During the exercise programme, as kinesiophobia reduced, so did the individuals pain, therefore baseline kinesiophobia scores could be important due to the correlation with pain changes. Further significant findings demonstrate that the programme increases objectively measured physical activity attributes and mobility in individuals with knee OA, therefore having a greater impact on developing and maintaining functio