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Pseudo-isotopies and embedded surfaces in 4-manifolds
Get PDFThe focus of this thesis is the study of smooth 4-dimensional manifolds. We examine two problems relating to 4-manifolds, the first pertaining to pseudo-isotopies and diffeomorphisms of 4-manifolds, and the second pertaining to embedded surfaces in 4-manifolds. We summarise our key results below.
A diffeomorphism of a compact manifold is pseudo-isotopic to the identity if there is a diffeomorphism of which restricts to on , and which restricts to the identity on and . We construct examples of diffeomorphisms of 4-manifolds which are pseudo-isotopic but not isotopic to the identity. To do so, we further understanding of which elements of the ``second pseudo-isotopy obstruction'', defined by Hatcher and Wagoner, can be realised by pseudo-isotopies of 4-manifolds. We also prove that all elements of the first and second pseudo-isotopy obstructions can be realised after connected sums with copies of .
If and are homotopic embedded surfaces in a -manifold then they may be related by a regular homotopy (at the expense of introducing double points) or by a sequence of stabilisations and destabilisations (at the expense of adding genus). This naturally gives rise to two integer-valued notions of distance between the embeddings: the singularity distance d_{\sing}(\Sigma,\Sigma') and the stabilisation distance d_{\st}(\Sigma,\Sigma'). We use techniques similar to those used by Gabai in his proof of the 4-dimensional light-bulb theorem, to prove that d_{\st}(\Sigma,\Sigma')\leq d_{\sing}(\Sigma,\Sigma')+1
Sanctioning Sacrilege: Towards Rereading Judges as Christian Scripture
Get PDFThis dissertation presents fresh readings of several episodes within the book of Judges and offers hermeneutical suggestions as a way towards rereading Judges as Christian Scripture. Reading with the grain of the text, I argue that several narratives are “sanctioning sacrilege” — they are condemning the characters and their actions not only when read as part of Israel’s Scriptures but also when reread as Christian Scripture. Chapter 1 surveys the reception of the Curse of Meroz (Judg. 5:23) in 18th century Britain and colonial America to provide a sympathetic account of how Christians in similar social settings could read and use a single verse from the book of Judges in a variety of ways. Chapter 2 offers a fresh interpretation of the Ehud narrative (Judg. 3:12-30) which rereads the protagonist as an anti-hero whose methods of deliverance are incongruous with the way YHWH has chosen to act through Israel. Ehud’s violent actions, though they effect liberation, are presented in a way that may appear more sinister when read as part of Israel’s Scriptures. Chapter 3 focuses on the concept of exemplarity and its resistance in early Jewish and Christian receptions of Samson. Chapter 4 continues to explore the characterisation of Samson within Israel’s Scriptures. The final chapter highlights the cultic dimension of Judges 17-21 and its thematic resonances within Judges and the Deuteronomistic History to argue that the refrain is a call for Israel’s leader—whoever that may be—to recommit to following YHWH and to lead Israel in doing what is right in YHWH’s eyes. It is argued that the function of Judges 17-21 is to provide a retrospective analysis of the problems Israel faces within the book of Judges, namely that the corrosion of Israelite society began with the corruption of the priesthood
The Problem of Political Credibility: Epistemic Realism and Cautious Liberalism
Get PDFIn this dissertation, I transform the problem of political authority into the problem of political credibility. In my terminology, credible political authorities satisfy the “confidence tenet,” which requires that the public can become reasonably confident that political authorities are legitimate. So, I defend a new type of realism “epistemic realism.” A conception of legitimacy should concede to the epistemic limits of reasonable citizens. It should avoid normative political principles that reasonable citizens will probably never become reasonably confident that political authorities do satisfy.
In search of political credibility, I argue against “highly moralised” conceptions of legitimacy that make legitimacy depend on promoting justice in some sense. In particular, I primarily argue against the political theorist David Estlund’s epistemic proceduralism. Estlund says liberal democratic states are legitimate political authorities because democratic mechanisms are fair or otherwise reasonably acceptable procedures and democratic decisions publicly reveal what promotes justice and the common good. However, I argue that epistemic proceduralism makes liberal democratic states lack credible political authority because reasonable citizens should lack confidence in whether democratic decisions do publicly reveal what promotes justice and the common good and if democratic mechanisms are fair procedures.
In search of a solution, I introduce “cautious liberalism.” A cautious conception of legitimacy prioritises avoiding harm over promoting justice for primarily epistemic reasons. Reasonable citizens can become reasonably confident liberal democratic states do avoid harm in some sense. In particular, a “peaceful instrumentalist” conception of legitimacy makes legitimacy depend on the preservation of a mutually beneficial peace. Liberal democratic states can become credible political authorities that reasonable citizens are reasonably confident are legitimate with peaceful instrumentalism. Reasonable citizens can publicly observe that liberal democratic states tend to make the vote remain more politically attractive than the pitchfork
The Cultural Politics of the Post-9/11 Superhero Film (2002-2019)
Get PDFThis thesis situates the contemporary superhero film within the context of 9/11 and the subsequent War on Terror. Whereas much commentary and scholarship has tended to read the genre’s contemporary resurgence as mirroring the ambivalence and uncertainty that characterises this period of recent US history, or indeed as directly participating in the aggressive, reactionary discourses that framed the War on Terror, my project proposes an extensive reappraisal of the form’s cultural politics. It highlights, the ways in which key texts of the superhero film’s contemporary “renaissance” come to perform a dissenting function with regard to the US’s pursuance of global counterterrorism following 9/11. My argument is based on a foundation of the analysis of three franchises that represent some of the period’s most well-known and salient examples of the genre’s contemporary resurgence: Sam Raimi’s Spider-Man trilogy (2002-2007), Christopher Nolan’s Dark Knight trilogy (2005-2012) and selected films from the Marvel Cinematic Universe or MCU (2008-2019). The analysis interrogates the genre’s entanglement with the political climate of militarisation and xenophobia that characterised the post-9/11 period. While texts from the post-9/11 resurgence of the genre undoubtedly exhibit certain reactionary elements, both consciously and otherwise, I foreground the fact that they also feature fully-fledged, even polemical reckonings with the excesses and consequences of the USA’s counterterrorism strategies and the broader legacies of systemic racism inflamed in the post-9/11 period.
While the superhero genre is one of the most lucrative in contemporary Hollywood cinema, it has simultaneously (and perhaps paradoxically) become a form through which the USA’s geopolitical dominance and its problematic, traumatic histories have been confronted. In a broader sense, this project therefore aims to explore the compelling and surprising capacity of popular culture to not only reflect the antagonisms of the recent past and present but also to confront and critique them
Subglacial topography and landscape evolution from radio-echo sounding data in the Evans-Rutford Region, southern Antarctic Peninsula.
Get PDFKnowledge of the subglacial bedrock topography of the Antarctic ice sheet is important for understanding modern and past ice flow as well as the present basal conditions. Inferring landscape evolution from the subglacial geomorphology can also provide insight into ice sheet interactions with other processes such as tectonics. This thesis utilises newly released radio-echo sounding data from the British Antarctic Survey GRADES-IMAGE radar survey to geomorphologically interpret the bed topography in the Evans-Rutford Region of Antarctica. The GRADES-IMAGE survey is a legacy radar survey that has not yet been examined in detail in terms of subglacial bed topography. In the work presented here, a new high-resolution Digital Elevation Model of the region has been generated, and the resulting subglacial landscape was mapped to delineate distinct geomorphological features. Hypsometric (area-elevation) analysis was carried out to characterise the landscape morphology, and a flexural isostatic rebounding model was applied in order to help consider the age and evolution of the pre-glacial landscape. The main finding from analysis of the subglacial features is the identification of ten flat plateau surfaces distributed throughout the study region. These plateaux sit under cold-based ice between deep incised glacial troughs, some of which have potential tectonic controls. Two populations of plateaux have been identified as potentially coherent pre-glacial surfaces. Three hypotheses are presented for the evolution of the regional landscape: passive margin evolution associated with the breakup of the Gondwana supercontinent, or an extensive planation surface that may have been uplifted either in association with the West Antarctic Rift System, or cessation of subduction at the base of the Antarctic Peninsula. Regardless of the process of formation, glacial erosion of the surrounding troughs likely coincided with the inception of the West Antarctic Ice Sheet, with the ice flow and erosion patterns topographically controlled by the regional tectonics
The Virgin Mary Between Ecclesia and Synagoga: Typology, Sin and Anti-Judaism in Medieval English Literature, c. 1200-1500
No full textIn this thesis I demonstrate the involvement of Synagoga, the figure of Jewish faith and community in the Christian imagination, in writing about the Virgin Mary in Middle English. I discuss texts that bolster Mary’s authority, such as miracle tales and retellings of the destruction of Jerusalem, as well as those that portray Mary as vulnerable. My first chapter discusses the well-known legend of Theophilus, but in three understudied yet sophisticated versions: I discuss their diverse treatments of Marian authority and the way in which Theophilus occupies the role of Synagoga. My second chapter argues for the portrayal of Mary as a Jew in the midst of conversion to Christianity at the foot of the Cross, examining a range of examples from Middle English poetry and drama, and Latin liturgies from England and Europe. My third chapter investigates a contrasting Marian tradition in the translation and adaptation of texts that describe the siege of Jerusalem; I focus on portrayals of the mother, Maria, who cannibalises her own child, as a Christian fantasy of extinguishing Jewish motherhood. My final chapter applies these findings of a more conflicted Marian tradition that incorporates the stigmatised emotions of Synagoga and the aspiration of Ecclesia to Sir Gowther and Sir Gawain and the Green Knight, which both use sexual violence as a mode of communicating with Mary in disparate ways, in order to demonstrate the presence of these emotional worlds in theological romance texts. Throughout the thesis I suggest that Synagoga and Ecclesia can be usefully thought of as emotional categories that can unsettle or reposition penitents in salvation history; Jewishness is thought of as a pre-Christian past, towards which Christian sinners may be figuratively transported
Distributed Real-Time Control Schemes for Microgrids Considering Uncertain Renewable Sources With Provisions for Resilient Operation
Get PDFThis thesis presents the integration and improvement of different technologies for optimal operation of microgrids, where the objective is to minimise cost of supply and maximise their renewable hosting capacity in a reliable and seamless manner. To this end, this work has proposed a hierarchical control framework for coordinating energy transactions between different stakeholders within the microgrid, and different microgrid clusters with distributed renewable resources integrated, in an economical and reliable manner.
The stability of the proposed primary control layer, and corresponding voltage bus, has been investigated using Lyapunov’s direct method to ensure it remains stable under all operating conditions. Meanwhile, the resiliency of the underlying communication network to maintain a fully connected network for the distributed control nodes has been verified mathematically using Graph theory by ensuring the underlying Laplacian matrix for the network always remains singular and without repeated zero eigenvalues, even following failures in any one individual communication node. This is done to ensure that the proposed control system is capable of reliably maintaining electrical service under normal and faulty conditions.
The hierarchical control framework relies on implementation of \ac{AI}-based techniques, mainly using Multi Agent Systems implemented within the Java Agent Development Framework environment to simulate a distributed control architecture for achieving real-time control of multiple resources within the microgrid (and clusters of microgrids). Meanwhile, using \ac{ML}, accurate forecast models have been developed for both electricity price forecast and wind speed (for distributed renewable resources) within the control architecture for optimising energy transactions between relevant stakeholders within the microgrid.
To verify the accuracy and compare the results of ML-based forecast models, this thesis proposes the use of statistical methods to ensure any differences between different forecast models are due to the model structure rather than randomness in the data. This comparison is carried out in addition to usual statistical comparison of different forecast models in terms of total absolute error, squared error and total cost.
At the hardware level, the hierarchical control system has been implemented using a connected network of Raspberry Pi computers acting as individual distributed control nodes with the microgrid simulated in a real-time simulator environment realised by an OPAL-RT (series OP5700) real-time simulator to test the viability of the control system to respond to a microgrid cluster system in real-time
Incorporation of pigment producing cells into novel 3D skin equivalents to study the role of the dermal compartment upon pigmentation in skin equivalents
Get PDFRecent generations of skin equivalents have started to become more complex and dynamic, which more closely capitulate the intricate workings of human skin. The importance of this research, since moving away from animal models, should not be understated. It is imperative to mimic the structure and hence the function of skin to ensure chemicals that are tested on this model system yield accurate results. As these models become more complex with inclusion of pigmentation, neurons or hair follicles, it is important to know how different models interact. Therefore, this thesis aims to understand the role of the dermal compartment and how it may influence the viability and efficacy of melanocytes within skin equivalents. The results showed that there is an important role for the dermis in providing support to the epidermis for the production of melanin and the transfer to HEKn cells in the Stratum Basale. Furthermore, there is proof of concept for the protocol and technology used to produce this pigmented skin equivalent
The Good Men of Suan Kulap An Ethnographic Genealogy of an Elite Thai School and the Making of Political Subjects
Get PDFThis thesis is concerned with the institutional culture of Suan Kulap Withayalai, Thailand’s oldest state-run secondary school and the alma mater of seven prime ministers. Using the critical theory of genealogy combined with methodologies common to ethnography, it traces the gradual development of the school’s symbolic and disciplinary infrastructure through time. In addition, it also provides a descriptive analysis of the school’s ritual events and ideological projects during the 2018/9 academic year. Using a range of sources, including historical documents, personal writings, life histories, and participant observation, the thesis explores how the school has been deeply implicated in the maintenance of power in Thailand and how it has sought to produce certain kinds of political subjects favourable to the interest of a shifting centre. It positions Suan Kulap as an overlooked institution in the scholarship of Thailand’s political culture. The thesis also augments and challenges the current literature pertaining to Thai education, which relies heavily on the study of pedagogic materials and has tended to characterise students as submissive recipients of the state’s ideological messaging. Highlighting the writings and words of those who worked and studied at the school, the thesis creates an alternative narrative of crypto-colonial innovation and sporadic conflict that is assiduously suppressed by the school administration. At a time when Thai high school students are protesting en masse against what they see as an authoritarian educational system, this thesis provides a historically informed ethnography of the practices that Thai schools engage in to maintain political stasis. More generally, the thesis is an intimate portrait of an institution deeply implicated, and reflective of, the ideological struggles and psychosocial movements that have shaped recent Thai history
Constraining the properties of gas around galaxies through absorption along multiple lines-of-sight
Get PDFIn this thesis we study the relationship between galaxies and the surrounding gas at redshifts < 1 using absorption spectroscopy along multiple, closely-spaced lines-of-sight. We use high-resolution UV spectroscopy of a projected quasar triplet at z ∼ 1 to detect absorption due to the Lyman-α transition of neutral hydrogen across the redshift range 0 < z < 1, as well as absorption lines attributed to numerous metal species. Alongside a variety of imaging and spectroscopic data covering foreground galaxies in this field in optical and near-infrared wavelengths, we attempt to constrain the likely origins of this absorbing gas in a range of galaxy environments.
Using our catalogue of ≈ 270 identified H i absorption systems, ≈ 150 metal line absorption systems, and ≈ 1000 galaxies with confident redshift measurements within a few Mpc of the sightlines, we apply statistical tests utilising this large sample size, and also attempt to model in detail the absorption around a smaller number of galaxies and galaxy groups.
We find that absorption is detected at a similar redshift in multiple lines-of-sight (separated by ∼ 400 kpc on average) significantly more frequently than in a sample
of mock absorbers with randomised redshifts. This is driven primarily by absorbers with column densities greater than 10 ^14 cm −2 , whilst weaker absorbers do not appear in multiple sightlines more often than the random sample, suggesting that they arise in the intergalactic medium.
Using H i, a bimodality is found in the azimuthal angle distribution of galaxy-absorber pairs with impact parameters < 300 kpc. We attribute this primarily to minor-axis outflows and major-axis accretion. This picture is supported by the observations that absorbers near the major axis show a significant preference towards line-of-sight velocities aligned with the kinematics of the galaxy (where available), and that those near the minor axis more frequently exhibit metal absorption (most notably O vi) at the same redshift.
By probing the gas around galaxies at multiple locations, we rule out simple disk, halo and outflow models around several isolated galaxies, and provide constraints on the velocities, opening angles or scale heights for any such structures around several additional galaxies. This can provide an additional diagnostic for helping to distinguish outflowing and infalling material in the circumgalactic medium. These simple models can plausibly fit ≈ 60 % of observed absorption within 300 km s −1 of our isolated galaxies.
We can also reproduce a large fraction (≈ 75 %) of absorption around pairs and groups of galaxies in this field using our ‘toy’ disk and outflow models, with
parameters generally similar to those around isolated galaxies. However, given the large number of model parameters available in groups of galaxies, it is difficult to rule out tidally-stripped or intra-group material resulting from the interactions between group galaxies.
Combined, these results indicate that outflowing and disk-like structures containing detectable levels of neutral gas are commonplace, although not ubiquitous, around galaxies with a wide variety of properties in a wide range of environments
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