362 research outputs found

    The method of homogenisation as a means to parameterise small-scale processes in the ocean and atmosphere

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    The first part of this thesis examines how finite-amplitude, small-scale topography affects small-amplitude motions in the ocean. The technique of homogenisation is used to develop an ‘averaged’ system based on the rotating shallow water equations in the presence of topography with horizontal extent much less than the wavelengths of the long waves in question. The extent to which the dispersion relations of PoincarĂ©, Kelvin and Rossby waves are modified from their flat-bottomed counterparts is illuminated, using a range of numerical and analytical techniques. Both random and regular periodic arrays of topography are considered, with the special case of regular cylinders studied in detail, because this case allows for highly accurate analytical results. We find formulae for the approximate frequency change for all three wave types, with a particularly simple analytic expression for the Rossby wave dispersion relation, extending previous results from the quasi-geostrophic regime. In addition to this, the manner in which trapped topographic Rossby waves affect the dispersion relations for a finite topography is illuminated. The second part examines the propagation of atmospheric waves through a small-scale convective cloud field. The method of homogenisation reveals that the small-scale clouds act to vertically redistribute the horizontal momentum and buoyancy profiles of the large-scale flow. Mathematically, this occurs due to the presence of non-local integral operators involving ‘transilient kernels’ in the homogenised equations. The dispersion relations are plotted for some of the wave modes propagating in a mid-latitude ÎČ -channel, which show that the cloud field slows the baroclinic waves, with low-frequency waves most affected

    Role of parathyroid hormone in the phosphaturia of extracellular fluid volume expansion

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    Role of parathyroid hormone in the phosphaturia of extracellular fluid volume expansion. Acute expansion of the extracellular fluid volume increases the urinary excretion of phosphate. The present study examined the importance of increased plasma parathyroid hormone concentration in the phosphaturia accompanying acute extracellular fluid volume expansion (ECVE). Infusion of a calcium-free Ringer's solution into dogs was associated with increased urinary phosphate excretion and serum immunoreactive parathyroid hormone concentration (iPTH), the latter being significantly correlated with a decrease in plasma ionized calcium concentration. Prevention of the fall in plasma ionized calcium concentration by infusion of a calcium containing Ringer's solution prevented the increase in serum iPTH but the magnitude of the phosphaturia was not affected. The phosphaturia associated with ECVE was also not affected in thyroparathyroidectomized (TPTX) dogs which received a maintenance infusion of bovine PTH. In contrast, in acutely TPTX dogs which did not receive a maintenance infusion of PTH, the phosphaturic response to ECVE was significantly depressed. These data indicate that 1) the increase in serum iPTH concentration following ECVE is the result of a fall in plasma ionized calcium concentration, 2) the increase in phosphate excretion accompanying ECVE is not dependent on an increase in serum iPTH concentration and 3) in the presence of a low or falling serum PTH concentration, the increase in phosphate excretion can be significantly blunted.RĂŽle de l'hormone parathyroĂŻdienne dans la phosphaturie consĂ©cutive Ă  l'expansion extracellulaire. L'expansion aiguĂ« du volume extracellulaire augmente l'excrĂ©tion urinaire du phosphate. Ce travail examine le rĂŽle de l'augmentation de la concentration d'hormone parathyroĂŻdienne dans la phosphaturie qui accompagne l'expansion du volume extracellulaire (ECVE). L'administration Ă  des chiens d'une solution de Ringer sans calcium est associĂ©e Ă  une augmentation de l'excrĂ©tion urinaire de phosphate et Ă  une augmentation de la concentration d'hormone parathyroĂŻdienne immunorĂ©active du plasma (iPTH). Cette derniĂšre est significativement corrĂ©lĂ©e Ă  la diminution de la concentration plasmatique du calcium ionisĂ©. L'empĂȘchement de la diminution de la concentration plasmatique du calcium ionisĂ© par l'administration d'une solution de Ringer contenant du calcium Ă©vite l'augmentation de iPTH dans le plasma mais n'affecte pas l'importance de la phosphaturie. La phosphaturie associĂ©e Ă  ECVE n'est pas non plus modifiĂ©e chez des chiens thyroparathyroĂŻdectomisĂ©s (TPTX) qui reçoivent une perfusion de PTH bovine. Au contraire chez des chiens TPTX aigus qui ne reçoivent pas de perfusion de PTX la rĂ©ponse Ă  ECVE est significativement diminuĂ©e. Ces rĂ©sultats indiquent que 1) L'augmentation de iPTH du plasma aprĂšs ECVE est la consĂ©quence d'une diminution de la concentration plasmatique du calcium ionisĂ©, 2) l'augmentation de l'excrĂ©tion du phosphate qui accompagne ECVE ne dĂ©pend pas de l'augmentation de iPTH du plasma et 3) quand la concentration plasmatique de PTH est faible ou en voie de diminution, l'augmentation de l'excrĂ©tion de phosphate peut ĂȘtre significativement masquĂ©e

    Unsteady turbulent line plumes

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    Optimizing Real-Time Wellness Intervention Studies in Healthcare Shift Workers: Outcomes from a Prospective, Single-subject Design Study of a Digital Sleep Aid

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    Sleep disorders associated with shift work impair alertness and increase risk of chronic physical and mental health disease. Though studying sleep aids in at-risk populations such as shift workers is critical to improving wellness, implementing robust studies to evaluate wellness interventions in live populations can be particularly challenging. We performed a prospective, single-subject design study in which we assessed the effect of noise-masking earbuds on sleep quality, sleepiness, and stress level in health care shift workers. Despite being gifted the technology at the end of the study, we faced poor participant accrual and study retention. Additionally, robust analysis of our intervention’s impact on post-shift alertness was underpowered due to variable participant scheduling. In order to make meaningful advances in improving wellness among such groups, studies emphasizing objective outcome measures while minimizing participant obligation to study protocols are ideal. Here, we discuss our experience studying a digital sleep intervention in a real-time setting and propose solutions for improving subject accrual, retention and methods for objective data collection in studies performed in a live shift worker population

    Britain and Europe: A new settlement? EPC Challenge Europe 23, May 2016

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    Britain's European problem, Stephen Wall; Britain's contribution to the EU: an insider's view, David Hannay; 'Foreign judges' and the law of the European Union, David Edward; The United Kingdom and the Charter of Fundamental Rights of the EU, Peter Goldsmith; European foreign policy: five and a half stories, Robert Cooper; External relations and the transformative power of enlargement, Heather Grabbe; Recalibrating British European policy in foreign affairs, Fraser Cameron; The European Union and the wider Europe, Graham Avery; From Common Market to Single Market: an unremarked success, Malcolm Harbour; Lost in translation: Britain, Germany and the euro, Quentin Peel; After Cameron's EU deal, Kirsty Hughes; Re-imagining the European Union, Caroline Lucas; Britain and European federalism, Brendan Donnelly; Europe's British problem, Andrew Duff

    Villages and Urbanization

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    In this article comments by politician Boris Johnson and economist Edward Glaeser exemplify narratives of global urbanization that portray rural villages as redundant and perpetuate outdated notions of urban–rural division. Simultaneously, traditional urban–rural dialectics are distorted by divisive new urban projects like gated communities styled as villages. This paper argues for development models that acknowledge the vital environmental and economic roles played by rural villages, and opposes artificially created “villages” in cities. In so doing, alternative readings of rurality and villages by Rem Koolhaas, Brazilian land reformers, Mahatma Gandhi, and critics of contemporary Indian literature and urbanism are considered

    The fables of pity: Rousseau, Mandeville and the animal-fable

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    Copyright @ 2012 Edinburgh University PressPrompted by Derrida’s work on the animal-fable in eighteenth-century debates about political power, this article examines the role played by the fiction of the animal in thinking of pity as either a natural virtue (in Rousseau’s Second Discourse) or as a natural passion (in Mandeville’s The Fable of the Bees). The war of fables between Rousseau and Mandeville – and their hostile reception by Samuel Johnson and Adam Smith – reinforce that the animal-fable illustrates not so much the proper of man as the possibilities and limitations of a moral philosophy that is unable to address the political realities of the state
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