Kingston University Research Repository

    On the speed of a test particle inside the Schwarzschild event horizon and other kinds of black holes

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    We present the results of an investigation of the speed of a radially infalling test particle crossing the event horizon of a black hole within a Schwarzschild spacetime. One finds that the speed as measured by a special class of observers, at rest outside the horizon and static inside the horizon, increases when the test particle approaches the horizon but decreases inside the horizon. The corresponding situation regarding black holes possessing both outer and inner horizons is also briefly discussed

    Experimental and mathematical investigation of the chaotic dripping mode

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    The dynamics of fluid flow unveils complicated dynamical behaviour. Systems such as a dripping tap are no exception. Flow through a nozzle produces three different modes: periodic dripping, chaotic dripping and jetting streams. This research concentrates on a study of the chaotic behaviour of a dripping tap. This involves both mathematical model studies and experimental studies. In addition, the work involves the development of an experimental facility to allow future study of the system in microgravity conditions. The facility to achieve microgravity conditions is a Drop Tower type, which uses a novel approach to achieve these conditions. The novelty is in the use of linear electromagnetic motors. The facility was built and is in the final stage of the commissioning process, and when it is ready it will allow up to 2.12 s of test time. The mathematical model uses an existing Mass-Spring-Damper model, with Reynolds numbers between 4 to 175, and a step size of 0.4. The results showed multiple bifurcation regions appearing before chaotic regions. Similarly, experimental results showed that some instabilities exist in this region. The model also explained and showed multiple bifurcations and an increase in dripping time due to instabilities, and has identified that those processes are due either to perturbations of the system or due to initial instabilities of the system. These results were confirmed by experiment. To achieve the required experimental goals a test module was developed whose requirements were set to fulfil the microgravity experiment conditions, in case future research is required. The experimental results showed some similarities with the mathematical model. At the same time, there was found to be quite a lot of disagreement. Results identified two different limit cycle attractors in periodic dripping mode: strong single-point attractors and regional attractors. Also, limit cycle attractors and strange attractors in chaotic mode were identified. More importantly, it has been identified that the chaotic region consists of areas where the system is stable (and produces a single region attractor), and others where the system is not (and this produces strange attractors), and there are points where, depending on the disturbances to the system, both types can be observed. The work done has led to several discoveries and achievements. Although the Drop Tower project could not be completed it may nonetheless be considered as a success. The facility has been fully assembled and calibrated to meet the set of design requirements, and to some extent was commissioned allowing future progress to discover modification requirements. The study of the Mass-Spring-Damper model led to the conclusion that the model is oversimplified and in its current state should be used only for descriptive purposes, when illustrating chaotic behaviour. Additionally, it was found that the model predicts bifurcations outside the experimentally determined chaotic region. Nevertheless, the work identified some possible improvements to the model. Experimentally it was found that the region of chaotic behaviour is located around a Reynolds number of 43 in contrast to what was previously reported. The study of the periodic dripping region showed that the system, if disturbed, can develop history dependent phenomena (where the subsequent drop periods follow a well identified sequence). Satellite drops were discovered to exist beyond the previously predicted value of flow rate. It was discovered that the fluid supply system can have a major effect on the drop dynamics (different types of post-detachment developments were found - termed here regular residual mass and wetted mass - along with the discovery of different types of drop detachment (regular mass, mid-size drops and jets) coexisting within the chaotic region. The drop horizontal disturbance study led to the unconfirmed discovery of two modes of vibrations, where the system response follows a standard damped response and an amplitude modulated damped response

    Group Spinner : recognizing and visualizing learning in the classroom for reflection, communication, and planning

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    Group Spinner is a digital visual tool intended to help teachers observe and reflect on children’s collaborative technology-enhanced learning activities in the classroom. We describe the design of Group Spinner, which was informed by activity theory, previous work and teachers’ focus group feedback. Based on a radar chart and a set of indicators, Group Spinner allows teachers to record in-class observations as to different aspects of group learning and learning behaviors, beyond the limited knowledge acquisition measures. Our exploratory study involved 6 teachers who used the tool for a total of 23 classes in subjects ranging from Maths and Geography to Sociology and Art. Semi-structured interviews with these teachers revealed a number of different uses of the tool. Depending on their experience and pedagogy, teachers considered Group Spinner to be a valuable tool to support awareness, reflection, communication, and/or planning

    British Muslim converts : an investigation of conversion and de-conversion processes to and from Islam

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    This study proposes an investigation into the formation of a new British Muslim identity, alongside various personal and social challenges and consequences many Muslim converts face as a result of conversion to, and in some cases from, Islam. The thesis analyses the factors and elements that greatly contribute to a more positive conversion experience and draws on insights from colonial history, the political climate, the Islamic fitrah, and western theories on conversion and identity development. Based on a qualitative study sample of thirty-four British converts, the thesis argues that many challenges Muslim converts face are due to them having a limited understanding of Islamic teachings and their rights. The study was guided by research questions: What are the anticipated benefits and positive elements that encouraged the start and continuation of an Islamic conversion journey? What constitutes a comfortable and balanced British Muslim identity and lifestyle for westerners? and What are the main problems and challenges new Muslims face that can lead to de-conversion? Is Lewis Rambo’s stage model, alongside Helen Ebaugh’s de-conversion stages appropriate for the study of conversion and de-conversion to and from Islam? It was found that those who enjoyed being Muslims were able to create a balanced British Muslim identity by negotiating and applying their own western values to their understanding of The Prophet Muhammad’s biography and The Quran, and integrated Islamic values into their own environments and everyday lives that were free from foreign cultural practices. It was important to understand what they were expecting to benefit from Islam and how they later perceived, practised, expressed and understood their new faith and identities as British Muslims. The study also examines how converts deal with Islamophobia and extremism, and how Islamic conversions can be perceived as a threat to White British identity, social class and values. The participants shared common difficulties regarding gender and racial discrimination, living among Muslims, identity development, marriage, parenting, Muslim culture, isolation, integration and practising Islam, but at different levels, and with differing consequences. The sacrifices, challenges and consequences faced by some individuals as a result of a de-conversion are explored, which includes living with hidden identities as ‘closeted disaffiliates’ out of fear of abuse and stigmatisation

    Engaging with birth stories in pregnancy : a hermeneutic phenomenological study of women’s experiences across two generations

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    Background: The birth story has been widely understood as a crucial source of knowledge about childbirth. What has not been reported is the effect that birth stories may have on primigravid women’s understandings of birth. Findings are presented from a qualitative study exploring how two generations of women came to understand birth in the milieu of other’s stories. The prior assumption was that birth stories must surely have a positive or negative influence on listeners, steering them towards either medical or midwifery-led models of care. Methods: A Heideggerian hermeneutic phenomenological approach was used. Twenty UK participants were purposively selected and interviewed. Findings from the initial sample of 10 women who were pregnant in 2012 indicated that virtual media was a primary source of birth stories. This led to recruitment of a second sample of 10 women who gave birth in the 1970s-1980s, to determine whether they were more able to translate information into knowledge via stories told through personal contact and not through virtual technologies. Results: Findings revealed the experience of ‘being-in-the-world’ of birth and of stories in that world. From a Heideggerian perspective, the birth story was constructed through ‘idle talk’ (the taken for granted assumptions of things, which come into being through language). Both oral stories and those told through technology were described as the ‘modern birth story’. The first theme ‘Stories are difficult like that’, examines the birth story as problematic and considers how stories shape meaning. The second ‘It’s a generational thing’, considers how women from two generations came to understand what their experience might be. The third ‘Birth in the twilight of certainty,’ examines women’s experience of Being in a system of birth as constructed, portrayed and sustained in the stories being shared. Conclusions: The women pregnant in 2012 framed their expectations in the language of choice, whilst the women who birthed in the 1970s-1980s framed their experience in the language of safety. For both, however, the world of birth was the same; saturated with, and only legitimised by the birth of a healthy baby. Rather than creating meaningful understanding, the ‘idle talk’ of birth made both cohorts fearful of leaving the relative comfort of the ‘system’, and of claiming an alternative birth. Keywords: United Kingdom, Pregnancy, Parturition, Childbirth, Midwifery, Personal narratives, Qualitative research, Hermeneutic
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