59 resultados para Braking in a Turn.

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


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Over the past decade or so a number of historians of science and historical geographers, alert to the situated nature of scientific knowledge production and reception and to the migratory patterns of science on the move, have called for more explicit treatment of the geographies of past scientific knowledge. Closely linked to work in the sociology of scientific knowledge and science studies and connected with a heightened interest in spatiality evident across the humanities and social sciences this ‹spatial turn has informed a wide-ranging body of work on the history of science. This discussion essay revisits some of the theoretical props supporting this turn to space and provides a number of worked examples from the history of the life sciences that demonstrate the different ways in which the spaces of science have been comprehended.

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This paper is concerned with the language of policy documents in the field of health care, and how ‘readings’ of such documents might be validated in the context of a narrative analysis. The substantive focus is on a comparative study of UK health policy documents (N=20) as produced by the various assemblies, governments and executives of England, Scotland, Wales and Northern Ireland during the period 2000-2009. Following an identification of some key characteristics of narrative structure the authors indicate how text-mining strategies allied with features of semantic and network analysis can be used to unravel the basic elements of policy stories and to facilitate the presentation of data in such a way that readers can verify the strengths (and weaknesses) of any given analysis – with regard to claims concerning, say, the presence, absence, or relative importance of key ideas and concepts. Readers can also ‘see’ how the different components of any one story might fit together, and to get a sense of what has been excluded from the narrative as well as what has been included, and thereby assess the reliability and validity of interpretations that have been placed upon the data.

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We present the results of photometric surveys for stellar rotation in the Hyades and in Praesepe, using data obtained as part of the SuperWASP exoplanetary transit-search programme. We determined accurate rotation periods for more than 120 sources whose cluster membership was confirmed by common proper motion and colour-magnitude fits to the clusters' isochrones. This allowed us to determine the effect of magnetic braking on a wide range of spectral types for expected ages of ˜600 Myr for the Hyades and Praesepe. Both clusters show a tight and nearly linear relation between J-Ks colour and rotation period in the F, G and K spectral range. This confirms that loss of angular momentum was significant enough that stars with strongly different initial rotation rates have converged to the same rotation period for a given mass, by the ages of Hyades and Praesepe. In the case of the Hyades, our colour-period sequence extends well into the M dwarf regime and shows a steep increase in the scatter of the colour-period relation, with identification of numerous rapid rotators from ˜0.5 Msun down to the lowest masses probed by our survey (˜0.25 Msun). This provides crucial constraints on the rotational braking time-scales and further clears the way to use gyrochronology as an accurate age measurement tool for main-sequence stars.

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Having experienced social and political structures of the 19th century Europe, Western- educated Egyptian elite used public institutions to force legislative structures and procedures that ruled out traditional housing forms and spatial systems. This essay detects direct and indirect impact of these changes that informed the spatial change of modern living in Egypt in the first quarter of the twentieth century. It offers analysis of socio-spatial practices and change in ordinary Cairenes’ modes of everyday living, using social routine and interaction to explain spatial systems and changing house forms during the first quarter of the 20th century. In doing so, the essay utilized archival documents, accounts, formal decrees, and novels of the time as well as conducting survey of house forms and spatial organizations in Old Cairo.

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The dynamics of predator-prey pursuit appears complex, making the development of a framework explaining predator and prey strategies problematic. We develop a model for terrestrial, cursorial predators to examine how animal mass modulates predator and prey trajectories and affects best strategies for both parties. We incorporated the maximum speed-mass relationship with an explanation of why larger animals should have greater turn radii; the forces needed to turn scale linearly with mass whereas the maximum forces an animal can exert scale to a 2/3 power law. This clarifies why in a meta-analysis, we found a preponderance of predator/prey mass ratios that minimized the turn radii of predators compared to their prey. It also explained why acceleration data from wild cheetahs pursuing different prey showed different cornering behaviour with prey type. The outcome of predator prey pursuits thus depends critically on mass effects and the ability of animals to time turns precisely.

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Alasdair MacIntyre condemns modern politics, specifically liberalism and the institutions of the liberal state, as irredeemably fallen. His core argument is that the liberal state encourages a disempowering ‘compartmentalization’ of people’s everyday roles and activities that undermines the intersubjective conditions of human flourishing. MacIntyre’s alternative is an Aristotelian politics centred on the notion of “practice.” Defined by justice and solidarity, this politics can only be realized, he claims, within local communities which oppose and resist the dictates of the administrative state and capitalist market. Here it is argued that MacIntyre’s notion of “practice” represents a compelling ethical-political ideal. However, the belief that this ideal is best realized within local communities is rejected. In privileging local community, MacIntyre relies on a reductive view of modern states and overlooks the institutional conditions of a just polity. Against this, it is argued that a politics of human flourishing cannot succeed without an emancipatory transformation of large-scale, trans-communal institutions, in particular the state.

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The turn within urban policy to address increasingly complex social, economic and environmental problems has exposed some of the fragility of traditional measurement models and their reliance on the rational paradigm. This article looks at the experiences of the European Union (EU) Programme for Peace and Reconciliation in Northern Ireland and its particular attempt to construct new District Partnerships to deliver area-based regeneration programmes. It highlights the need to combine instrumental and interpretative evaluation methods in an attempt to explain the wider contribution of governance to conflict resolution and participatory practice in local development. It concludes by highlighting the value of conceptual approaches that deal with the politics of evaluation and the distributional effects of policy interventions designed to create new relationships within and between multiple stakeholders.

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Contemporary political disputes have a long history of expression and contestation through the genre of history-writing in Ireland. The role of history writing and political science writing during the nearly 40 years of the so-called 'Troubles' has been no exception to this. Battles between competing versions of what the conflict 'is about', mediated through academic and popular texts have themselves in turn become constitutive of it. This builds upon centuries of the representation of the complicated politics of this island as 'an issue' in British domestic politics - first 'the Catholic question', then 'the Irish question'. The location of political power outside the island for centuries has created successive battles for the representation of sectional interests in a metropolitan centre. The skills of propaganda, history writing, newspaper writing have consequently been deployed at a remarkable level of skill and intensity. In the recent period one of the consequences of this has been the removal from the debate of the actuality of partition; this builds upon a particular historical representation of partition as an historical inevitability. To seek to restore partition to the debate is not to call for its undoing but to recognise that seeking to circumvent debates about its origins in the key period of democratisation in Irish politics (1880-1920) has been counter-productive. This essay examines the genealogies of partition in Irish and international contexts in the light of these battles for representation, and aims to return a lost dimension to the debate about the so-called 'Troubles'in Ireland. The genealogy of partition is the issue that has been marginalised in academic study and this has affected both policy and politics.

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Based on an accurate first principles description of the energetics in H-bonded potassium-dihydrogen-phosphate crystals, we conduct a first study of nuclear quantum effects and of the changes brought about by deuteration. Tunneling is allowed only for clusters involving correlated protons and heavy ion displacements, the main effect of deuteration being a depletion of the proton probability density at the O-H-O bridge center, which in turn weakens its proton-mediated covalent bonding. The ensuing lattice expansion couples self-consistently with the proton off-centering, thus explaining both the giant isotope effect and its close connection with geometrical effects.

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The impedance and radiation pattern parameters of a lambda/2 quadrifilar helix antenna (QHA) with turn angles in the range 0 degrees to 235 degrees are analyzed. It is shown that by selecting the helix turn angle to satisfy the minimum bandwidth and beamwidth requirements, an improved electrical performance and a reduction in the physical size of the antenna is obtained. This is demonstrated by comparing the performance of a conventional half turn QHA with structures having a smaller pitch length. The computed results are validated by experimental data at L-band.

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In his presidential address to the Belfast meeting of the British Association for the Advancement of Science in 1874, John Tyndall launched what David Livingstone has called a ‘frontal assault on teleology and Christian theism’. Using Tyndall's intervention as a starting point, this paper seeks to understand the attitudes of Presbyterians in the north of Ireland to science in the first three-quarters of the nineteenth century. The first section outlines some background, including the attitude of Presbyterians to science in the eighteenth century, the development of educational facilities in Ireland for the training of Presbyterian ministers, and the specific cultural and political circumstances in Ireland that influenced Presbyterian responses to science more generally. The next two sections examine two specific applications by Irish Presbyterians of the term ‘science’: first, the emergence of a distinctive Presbyterian theology of nature and the application of inductive scientific methodology to the study of theology, and second, the Presbyterian conviction that mind had ascendancy over matter which underpinned their commitment to the development of a science of the mind. The final two sections examine, in turn, the relationship between science and an eschatological reading of the signs of the times, and attitudes to Darwinian evolution in the fifteen years between the publication of The Origin of Species in 1859 and Tyndall's speech in 1874.