Apollo - University of Cambridge Repository
Apollo is the institutional repository of the University of Cambridge, managed by the Open Research Systems team based in Cambridge University Library. The Repository is committed to store and preserve the University’s research outputs. Research outputs can include, but are not limited to, publications, conference proceedings, book chapters, monographs, theses, various forms of research data (video recordings, spreadsheets, computational scripts, code, images etc.), presentations and others.
Ventilation, stratification and flow instability driven by vertically distributed buoyancy sources
This thesis consists of three different projects on flows driven by vertically distributed buoyancy sources. Following a storyline, the three serial problems have inherent connections. In the first project, a theoretical model is developed for the steady multi-layered flow induced by a plane vertically distributed buoyancy source producing a turbulent wall plume in a ventilated box. The boundary condition at the wall for each layer is established by deducing the turbulent entrainment rate. Using conformal mapping techniques and Poisson's integral theorem, closed-form solutions for the streamfunction of the induced flow in each layer are established. While the flow near the ceiling was overlooked in the classic model for the multi-layered stratification, after considering the possible flow scenarios, the stratification is reevaluated herein by incorporating an entraining ceiling current. With a markedly thinner top layer, the refined stratification matches well with available experimental observations -- agreement that was absent for the classic model -- the model overcoming the previous over-prediction in the number of interfaces. The magnitude of dimensionless flow velocity, independent of the wall buoyancy flux and physical scale of the box, decreases significantly with the number of layers. Three types of layer, each with a distinct induced flow pattern, are distinguished and their implications for indoor airflow considered. Notably, the flow in the base layer represents a continual and smooth flushing of air between the inlet opening and wall plume, whereas any intermediate layer is almost entirely comprised of near-stagnant air. Second, the linear temporal stability characteristics of a thermal plume generated along a heated vertical cylinder is investigated theoretically. Special focus is given to the uniform-wall-buoyancy-flux case whereby the cylinder surface sustains the same linear temperature gradient as the environment. A competition between the axisymmetric and helical wave modes is a remarkable feature of the instability, distinguishing these `annular wall plumes’ from free plumes/jets for which the helical mode is usually dominant. It is found that higher surface curvature stabilises the temporal axisymmetric mode significantly, but only has moderate effects on the helical mode. The most temporally unstable perturbation mode switches from a helical into an axisymmetric mode when the Prandtl number increases beyond a critical value. Both the roles of shear and buoyancy during the destabilisation are identified through an energy analysis which indicates that while (mean) shear work is usually a major source of perturbation energy, buoyancy work manifests for long-wave axisymmetric perturbation modes, and for thin cylinders and high Prandtl numbers. In heat transfer applications, to promote transition to turbulence and enhance convective heat transfer, working fluids of either sufficiently low or high Prandtl numbers are preferred; cylinders of too-small dimensionless radii should be avoided. The third project presents a numerical approach innovated to overcome the numerical difficulty of tracking the eigenmodes when evaluating a fully numerical dispersion relationship. Based on this numerical approach, the absolute/convective instability of the same annular plume as that in the second project is analysed. Following a discussion about the numerical issue of eigenmode tracking and some previous methods to alleviate it, a bespoke `initial value approach' is proposed, which primarily consists of making an estimation of the target eigenmode via solving a set of successive initial value problems, and identifying the target eigenmode from the exact solutions. Furthermore, this numerical approach is adapted into an iterative scheme, which facilitates the computation of the absolute/convective instability over the parameter space in an automatic and efficient way. For the specific temperature configuration considered herein, an annular wall plume is always absolutely stable, whereas decreasing the cylinder radius from the planar limiting case first decreases and then increases the tendency of the flow towards being absolutely unstable. The helical mode is especially susceptible to being absolutely unstable on very thin cylinders. A high Prandtl number promotes the absolute instability for both azimuthal perturbation modes. Finally, several conditions for the occurrence of plume detrainment are proposed based on the results and a hypothesis which connects the absolute instability to the detrainment phenomenon. The numerical approach also enables the absolute/convective instabilities of multiple branches of a general dispersion relationship to be computed and assessed simultaneously.
Multilevel simulation of hard-sphere mixtures.
(AIP Publishing, 2022-09-28)
We present a multilevel Monte Carlo simulation method for analyzing multi-scale physical systems via a hierarchy of coarse-grained representations, to obtain numerically exact results, at the most detailed level. We apply the method to a mixture of size-asymmetric hard spheres, in the grand canonical ensemble. A three-level version of the method is compared with a previously studied two-level version. The extra level interpolates between the full mixture and a coarse-grained description where only the large particles are present-this is achieved by restricting the small particles to regions close to the large ones. The three-level method improves the performance of the estimator, at fixed computational cost. We analyze the asymptotic variance of the estimator and discuss the mechanisms for the improved performance.
Damage, dirt and change over time: documenting conditions at the University of Cambridge Museum of Archaeology and Anthropology
(Informa UK Limited, 2023)
How does one ethically care for a global collection shaped and maintained within a colonial context? How do we address institutional responsibilities in a way that is transparent, rigorous and reparative? This article discusses on-going conservation research at the University of Cambridge Museum of Archaeology and Anthropology as part of a five-year storage relocation project. Moving beyond key vocabularies and abstract critique, this work examines the potential role of conservation in documenting and interpreting evidence for damage, displacement and erasure related to methods of colonial knowledge production and historic museum practice. The work includes a consideration of the language used to distinguish modifications resulting from museum practice such as the application of pesticides; monitoring change over time; the expectation of object longevity; and the potential consequences of disrupted traditions of maintenance and knowledge exchange. The article concludes by reflecting on the ways in which technical vocabularies, documentation and decision-making processes can shape and even improve the ways in which these collections are studied, valued and utilised by a diversity of stakeholders.
Beyond the Monomyth: Jung and the Children's Book in the Adult Imagination
Abstract: ‘Beyond the Monomyth: Jung and the Children’s Book in the Adult Imagination’, Andrew Peter McCormack I developed my interest in Jungian theory and children’s literature when I began investigating literature which embeds the children’s book within adult storyworlds. My meta-level analysis of the children’s book in the adult cultural imagination evidenced a deep relationship between core Jungian concepts and the construction and consumption of the children’s book, which I argue has come to function as an inheritor to myth, legend, folklore and the fairytale in providing a shared lexicon of images by which individuals and communities come to and continue to understand themselves and one another. My research evidences how four core Jungian concepts - that of the complex; the inner or eternal child; the shadow; and the collective unconscious - are illustrated, dramatised, and challenged by cultural depictions of the children’s book in adult fiction, thereby demonstrating the deep interconnection between Jung and the children’s book. This thesis seeks to reveal and explore the depth of the relationship between Jungian theory and the children’s book, which has been overshadowed in both the literary academy and the popular imagination by an undue focus on the monomyth template - or hunting for iterations of the hero’s journey - developed by post-Jungian thinkers, and a reductive dilution of Jungian concepts de-contextualised from Jung’s own rich, multi-faceted and challenging philosophy and psychology. Frank McLynn asserts in his 1996 biography of C.G. Jung that Jung ‘never wrote anything significant on child psychology’, and ‘always found the subject a bore’ (517). A significant gap in the literature evidences an acceptance of this misreading of Jung’s work, which this thesis seeks to address. The publication in 2010 of Children’s Dreams, notes from Jung’s seminars on the subject given between 1936 - 1940, provided me with a methodological as well as conceptual starting point for this project. It is true that Jung did not analyse the dreams of children per se, but his attention to the dreams of children as remembered by them in adulthood speaks to my thesis that the symbolic children’s book functions in parallel to the remembered childhood dream: as a nexus of images and ideas of significance to one’s self-perception and interaction with others in broader social networks and cultures throughout the life cycle. Children’s literature scholarship and childhood studies, too, are in the midst of a deepening engagement with cross-generational networks and the phenomenon of recursive adult engagement with the culture of childhood. Thus this intervention speaks in a timely way both to Jungian communities and to scholars of children’s literature and culture. I challenge McLynn’s assertions that Jungian theory is of little interest to scholars of children’s literature and the culture of childhood, and its inverse: that children’s culture offers little foothold for the serious Jungian scholar. My method for analysis draws upon the recent work of Jungian literary theorist Susan Rowland, whose conviction ‘that Jungians can aid the study of literature while literary critics can similarly inform Jungian psychology’ (2019: 1) offers an alternative to the monotonous monomyth method - or what Terence Dawson terms ‘instant Jung’ (2008: 290) - responsible for Jung’s recent relative elision from the literary academy. Jung is conspicuous for his absence, in particular, from the field of psychoanalytic children’s literature scholarship: the 2000s saw the publication of Karen Coats’s Lacanian study Looking Glasses and Neverlands (2004), and the 2010s Kenneth Kidd’s Freud in Oz (2011), which address Jung’s influence in the field only cursorily. Kidd’s assertion that ‘not a few Jungian analyses of the fairy tale and other genres are vulgar and reductive, missing out on the complexities of Jung’s actual discourse’ (2011: 11) articulates part of the challenge I aim to meet in this project, in bringing Jung’s actual discourse into dialogue with contemporary texts of significance to the study of children’s literature. As my analysis will show, the neglect of Jung within the academy of children’s literature has not impeded the potential for the relationship between Jungian theory and the children’s book to flourish in the hands of artists and authors. The children’s book functions, instead, in the adult imagination as a particularly rich site for the dramatisation of the maturation process, and thus as a literalisation of Jung’s concept of individuation, or the integration of consciousness and the unconscious in the achievement of psychic selfhood. By contextualising the symbolic children’s book within adult culture I interrogate the potential this provides for interaction between real children and the remembered child of the now-adult reader and author. The index of the children’s book can be read as a focalising point within the life cycle: a multivalent nexus offering the potential for the reader’s self-knowledge to deepen and change while the text remains ostensibly the same. In Jungian teleology, one looks back so as to look forward, and one looks forward so as to better navigate the present. The implications of my work suggest the Jungian lens as one of crucial significance to understanding children’s literature: what it has done, what it is doing, and what it might yet go on to do.
Maternal Resistance to Thyroid Hormone ß and pregnancy outcomes (DOI: dgad350) in The Journal of Clinical Endocrinology & Metabolism
(Endocrine Society, )
Resistance to thyroid hormone (RTH), a dominantly-inherited disorder, typically due to heterozygous mutations (over 230 different mutations described hitherto) in the thyroid hormone receptor (TR) which mediates negative feedback by thyroid hormones (TH) within the hypothalamo pituitary-thyroid axis, is characterised by raised circulating TH (free T4 and free T3) and non suppressed TSH. The clinical phenotype of RTH is variable, encompassing both hyperthyroid (e.g. failure to thrive in infancy; anxiety, tachycardia, low body weight in adults) and hypothyroid (e.g.dyslipidemia, steatosis) features, attributable to the actions of elevated TH on either hormone sensitive, TR-expressing tissues or hormone-resistant, TR-expressing organs respectively (1). Knowledge that conventional maternal hyperthyroidism (e.g. due to Graves’ disease) has deleterious consequences in pregnancy prompts consideration of what the outcomes of pregnancies in which a hyperthyroxinemic mother with RTH carries a fetus of either concordant (TR mutant), or discordant (wild type or normal TR) genotype, might be.
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