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Planetary nebulae (PNe) are the glowing, gaseous remnants of low to intermediate mass stars. As light from the star passes through the layers of gas and dust, a distinct spectrum is produced, with a variety of emission, absorption and continuum features. This means that a large number of physical properties can be inferred from a single spectroscopic observation. This thesis concentrates on the properties of evolving PNe which are bright in the 1-0 S(1) emission line of molecular hydrogen (H2), observed by the UWISH2 survey. The first part of this thesis is the reduction and analysis of K-band spectra of 29 true and candidate PNe from this survey. The Bry line is identified in all but two objects, signifying the presence of H+. 13 candidate PNe have spectra with the Bry line, but show no signs of Hα emission in optical surveys, confirming the need for infrared observations to reveal PNe obscured by dust in the Galactic Plane. Ratios of fluxes of H2 and hydrogen recombination lines are used to link the dominant H2 excitation mechanism with PN morphology and evolution. In line with previous results, we find that UV-fluorescence plays a greater role in W-BPNe (bipolar PNe with pinched waists), while R-BPNe (bipolar PNe with ring structures) are predominantly thermally excited. Using the relative spatial extents of HII and H2 emission, which act as a proxy for evolution, we find that W-BPNe are likely to be younger objects, while the R-BPNe are more evolved. The second part focusses on Abell 53 - a little-studied PN consisting of a bright ring of HII and H2 emission. Multi-wavelength observations are obtained, including photometry from the near-UV to radio, along with optical and near-IR long-slit spectra. After correcting for extinction, these observations are used to conduct a detailed analysis in order to determine the properties of Abell 53, including gas temperature and density, along with physical dimensions of radius and distance. The photoionisation code Cloudy is used with the Markov-Chain Monte Carlo (MCMC) optimisation procedure in order to find a best-fit set of parameters to describe the optical observations. A good fit is found using a star approximated by a blackbody with an effective temperature and luminosity of 104 kK and 400 Lʘ respectively, surrounded by a spherical shell spanning from 0.09 to 0.17 pc, with density 830 cm-3 and filling factor 0.48. Observed line ratios of H2 1-0 S(1) to Hα and 2-1 S(1) are reproduced by replacing the outer portion of the previous shell with a higher-density region of ~ 15000 cm-3, thickness 0.010 pc and a constant temperature of 2100 K. The third part uses a sequence of photoionisation models, such as the one used for Abell 53, in order to replicate H2 emission from an evolving PN. Each model in the sequence represents a PN at a particular evolutionary stage, defined by parameters describing the incident radiation field, expansion and density. Using values representative of a typical PN, Hα surface brightnesses were obtained, comparable to observations and hydrodynamical models, leading us to believe that this method is reliable. The downside of using a sequence of static models, rather than a time-dependent radiation-hydrodynamic model, is that the timescales over which certain reactions take place must not exceed the time intervals between successive models. In order to try to match the surface brightnesses in the UWISH2 survey, constant density models were developed with densities up to the highest observed in knots in PNe. We paid special attention to the reaction rates of H2 formation on grain surfaces, and total H2 destruction, which are highly dependent on density. Unless the density is at the highest end of possibilities, the timescales required to reform H2 on grains is much longer than the intervals between successive models, meaning that the CS flux changes before the models have time to react to the changes. The H2 surface brightness for the 107 cm-3 density model while on the cooling track are of the same order as those in the UWISH2 survey, and so it is likely that this emission is compatible with emission from dense knots.

Cavity quantum electrodynamics (cavity QED) with single atoms and single photons provides a promising route toward scalable quantum information processing (QIP) and computing. A strongly coupled atom-cavity system should act as a universal quantum interface, allowing the generation and storage of quantum information. This thesis describes the realisation of an atom-cavity system used for the production and manipulation of single photons. These photons are shown to exhibit strong sub-Poissonian statistics and indistinguishability, both prerequisites for their use in realistic quantum systems. Further, the ability to control the temporal shape and internal phase of the photons, as they are generated in the cavity, is demonstrated. This high degree of control presents a novel mechanism enabling the creation of arbitrary photonic quantum bits.

This dissertation presents three papers demonstrating how integrating graph (network) and language (text) data in machine learning models can enhance computational social science models. These two types of data are ubiquitous across many contexts in which computational social scientists work (e.g., social media platforms, online markets, and the Web as a whole). Relatively little research has analyzed how to model network and text data together at scale, partly since models for these data are often computationally expensive but also because statistical models for them require expert-driven decisions on feature engineering and how they are related within models. The first paper in this dissertation combines node and text embeddings in a downstream classification model to study mental health dynamics on Reddit. The second paper cascades knowledge graph classifications to a text clustering model to study how demographic confounding causes extreme instances of lifestyle politics using aggregated Facebook interest data. Finally, the third paper uses graph and language data from Amazon to study the spread of political and lifestyle polarization in the large online market and tests how network and morality features explain the presence of lifestyle polarization. Together, the three studies show how integrating graph and language data in machine learning models can facilitate computational social science not only by improving such models’ power, efficiency, and ease of use but also by allowing us to test new hypotheses and explain black box models. The conclusion contextualizes findings for academia and industry.

Evictions, defined as the forced removal of a tenant by their landlord, have increasingly become a topic of interest for housing researchers because of the documented negative impact evictions have on renters and the communities they live in. Unfortunately, research on evictions is limited because many court systems do not provide eviction data in forms accessible to investigation. This research project benefits from a unique data set that contains every eviction filed in Shelby County General Sessions Court from 2016-2019. I find that 110,834 evictions were filed during this period, and the average eviction filing rate was an alarmingly high 17.7%, which remained remarkably consistent from year to year. I also found that evictions were incredibly concentrated into a handful of zip codes. Out of the 32 zip codes in Shelby County, the five zip codes with the highest eviction filing rates make up 45.4% of all eviction filed from 2016-2019. Possible reasons for Memphis high rate of evictions are a court process that favors landlords and an influx of private equity into the single-family rental market in the wake of the subprime mortgage crisis of 2008. I recommend a comprehensive transformation of the American housing system with a suite of proposals aimed at solving broad housing affordability issues to remedy the eviction issue. Given current political realities that make short-term adoption of these policies unlikely, I also recommend maintaining and expanding local eviction prevention measures adopted during the Covid-19 pandemic after the pandemic has subsided

Helium-3 detectors are efficient, reliable neutron detectors, but their high demand has reduced their supply to a very miniscule level, making them very expensive. The goal of this project is to test and evaluate an alternative produced by industry. Current testing is being done with a Lithium Zinc Sulfide (6LiF:ZnS(Ag)) detector from Aspect used in their portal monitors. There are three basic requirements for neutron detectors used in nuclear safeguards and security: 1) high absolute detection efficiency, 2) maintaining neutron detection efficiency when simultaneously exposed to a high gamma ray exposure rate, and 3) the ability to maintain neutron detection rate in all operational temperature ranges. All of these requirements will be tested with the detector mentioned above, including comparisons to a helium-3 slab counter from Rapiscan. This thesis describes the results of said detector systems, which were tested at Oak Ridge National Laboratory.

The effects of soy protein isolate incorporation on the physico-chemical properties of starch-based gummi confections were investigated using thermal and rheological analyses, as well as supportive sensory and spectroscopy studies. The overall objectives of this study were to characterize the textural and rheological changes upon varying levels of soy addition to starch confections and consequent changes to quality parameters and second to assess the impact of incorporation of soy protein isolate on storage stability. Texture profile analysis was conducted to simulate mastication and to quantify, along with a hedonic sensory panel, the effects on gummi acceptability as a function of texture. Increasing levels of soy protein yielded samples that were progressively less firm and cohesive, caused either by starch network dilution and/or disruption. The softening effect of soy protein was observed throughout storage. Addition of soy protein improved the texture acceptability, presumably by decreasing perceived shortness, a texture defect associated with overly-firm gelled confections. Rheometric analyses were conducted to determine the relationship between gummi viscoelastic properties and the applied stress and rate thereof. Addition of soy protein was found to progressively decrease the yield stress to suppress yield stress increase at each storage interval. The viscoelastic crossover frequency, an indicator of stability, was also found to decrease as soy protein concentration increased and to have a lower rate of increase during storage.Water-dependent interactions were characterized as they relate to soy concentration and storage time. Thermogravimetric analysis results indicated that the primary water population was more easily removed in high-soy protein formulations. Additionally, as storage time increased, soy protein maintained relative homogeneity of the primary water population and removal of water required lower temperatures with the soy formulation, indicating less entrapment of water throughout the storage period studied.Results from differential scanning calorimetry did not indicate a significant shift in the glass transition temperature as soy concentration increased, likely due to the low concentration of plasticizing water. Neither gummi system exhibited distinct endotherms associated with starch melting regardless of treatment; soy protein inclusion did not prevent complete starch gelatinization during the confection process, as evidenced by the lack of the typical starch melting endotherm. However, the addition of soy protein was able to prevent an increase in the Tg of the gummi confections, perhaps by interfering with starch re-association.The changes in monomeric anthocyanin quantity, expressed as units of cyanidin 3-glucoside, which occurred as a result of confection processing were also analyzed using ultraviolet spectroscopy. The soy gummi confections yielded higher anthocyanin recovery, perhaps due to the greater heat dissipation caused by a lower cooking viscosity. Hedonic sensory analysis showed that addition of soy protein improved acceptance for texture and flavor. The mechanism of improvement is thought to be related to the decreased shortness of the product which augments mouth-feel and flavor release. All results indicate that soy protein has potential as a processing aide in gelled confections by modulating physical properties: decreasing gel rigidity, improving sensory characteristics, improving natural pigment recovery, and homogenizing water populations.

It is a generally accepted view in the literature on civil-military relations and military sociology that the military is a ‘Janus-faced’ organisation. One of its faces has to watch the strategic requirements and the other face looks at its parent society. The Janus-face analogy indicates that the strategic and societal views are intrinsically antithetical. The notion of the antithetical relationship between liberal ideology and military security was established as early as the 1950s in Samuel Huntington’s seminal book The Soldier and the State. This thesis is conceived as a critical debate with Huntington, challenging, in particular, the notion that societal and functional imperatives are inevitably distinct and antithetical. The aim of this thesis is to analyse in what ways liberalism – as a meta-ideology or a guiding ethos – determines the military capacities of West European societies. The empirical analysis has been carried out on the cases of the German Bundeswehr (from the 1950s onwards) and the British armed forces (from the beginning of the 20th Century onwards). Despite the enormous divergence these two cases represent, a similar pattern of behaviour is recognisable in them. This examination reveals that specific policies, institutions and practices are preferred because of their relation to liberal principles. Sometimes liberal norms are used merely to advocate an otherwise necessary policy, such as universal conscription at the time of emergency. Regarding other issues, such as the right to conscientious objection, liberal principles are the most relevant causal factor. Among the issues affected by liberal ideology are also the varieties of military mission, military ethics and professional identity of soldiers. The case studies examined in this thesis demonstrate that a meaningful adaptation of the military to the principles possessed by its parent society can be, more often than not, desirable also from the perspective of security strategy.

Major General Orde Charles Wingate (1903-1944) is one of the most controversial British military commanders of the last hundred years. This controversy stems from two broad sources: the first of these was his idiosyncratic and occasionally tempestuous personality; the second is the alleged 'radicalism' of his military ideas, both of which contributed to a series of feuds and acrimonies with other senior officers in the British Army. Wingate first came to the notice of his seniors when he organised the Special Night Squads, a specialist counterterrorist force comprising British soldiers and Jewish police, in Palestine in 1938; in 1940-41, he planned and commanded covert operations, in cooperation with local guerrillas, inside Italian-occupied Ethiopia; he is best remembered in the UK, however, for his command of Long Range Penetration Groups, or 'Chindits', in Burma in 1943-44. The Chindit operations in particular split opinion in the literature, debates in which centre upon their cost-effectiveness and their actual worth, and many imply that they marked a major departure from British military thought and practice hitherto. Some post-war authors have attempted to present Wingate as 'ahead of his time', a forerunner of various late twentieth and twenty-first century models of warfare. However, a survey of Wingate's own papers – closed to the public until 1995 - and other contemporary documents and testimony, reveals an organically evolving and increasingly coherent body of military ideas consistent with the military thought and practice of the British Army in the theatres where Wingate served, that did not mark a radical departure from them until almost the end of his career. Wingate was firmly 'of his time', and not of any other.