VictorJuiz/thesis huggingface dataset:
Diffusion-weighted magnetic resonance imaging with readout-segmented echo-planar imaging
Keywords: 3D multi-slab diffusion MRI
High-resolution diffusion MRI
Simultaneous multi-slice acceleration

Diffusion-weighted (DW) magnetic resonance imaging is an important neuroimaging technique that has successful applications in diagnosis of ischemic stroke and methods based on diffusion tensor imaging (DTI). Tensor measures have been used for detecting changes in tissue microstructure and for non-invasively tracing white matter connections in vivo. The most common image acquistion strategy is to use a DW single-shot echo-planar imaging (ss-EPI) pulse sequence, which is attractive due to its robustness to motion artefacts and high imaging speed. However, this sequence has limited achievable spatial resolution and suffers from geometric distortion and blurring artefacts.
Readout-segmented echo-planar imaging (rs-EPI) is a DW sequence that is capable of acquiring high-resolution images by segmenting the acquisition of k- space into multiple shots. The fast, short readouts reduce distortion and blurring and the problem of artefacts due to motion-induced phase changes between shots can be overcome with navigator techniques.
The rs-EPI sequence has two main shortcomings. (i) The method is slow to produce image volumes, which is limiting for clinical scans due to patient welfare and prevents us from acquiring very many directions in DTI. (ii) The sequence (like other diffusion techniques) is far from the optimum repetition time (TR) for acquiring data with the highest possible signal-to-noise ratio (SNR) in a given time. The work in this thesis seeks to address both of these important issues using a range of approaches.
In Chapter 4 a partial Fourier extension is presented, which addresses point (i) by reducing the number of readout segments acquired and estimating the missing data. This allows reductions in scan time by approximately 40% and the reliability of the images is demonstrated in comparisons with the original images.
The application of a simultaneous multi-slice scheme to rs-EPI, to address points (i) and (ii), is described in Chapter 5. Using the slice-accelerated rs-EPI sequence, tractography data were compared to ss-EPI data and high-resolution trace-weighted data were acquired in clinically relevant scan times.
Finally, a 3D multi-slab extension that addresses point (i) is presented in Chapter 6. A 3D sequence could also allow higher resolution in the slice direction than 2D multi-slice methods, which are limited by the difficulties in exciting thin, accurate slices. A 3D version of rs-EPI was simulated and implemented and a k-space acquisition synchronised to the cardiac cycle showed substantial improvements in image artefacts compared to a conventional k-space acquisition.
An urban geography of the Roman world, 100 B.C. To A.D. 300
Keywords: SETTLEMENT SCALING THEORY
ROMAN
NUMBER
POPULATION DENSITY
SEAS
URBAN POPULATION
RIVERS
GEOGRAPHY
ECONOMIC GROWTH
TOTAL POPULATION
ARCHAEOLOGY
POPULATION
URBAN GEOGRAPHY
CHANGE OVER TIME
ANCIENT HISTORY
CLASSICAL ARCHAEOLOGY
DISTRIBUTION
URBAN HIERARCHY
HINTERLANDS
ECONOMIC INTEGRATION
THE RANK-SIZE RULE
SETTLEMENT HIERARCHY
CONNECTIVITY
RURAL POPULATION
HISTORY
URBANIZATION RATE
TOWNS
URBAN CENTRES
ECONOMICS
CENTRAL PLACE THEORY
MONUMENTALITY
COLONIA
CIVIC STATUS
URBAN
URBANISM
URBAN THEORY
ROADS
URBANIZATION
LONGUE DURÉE
COLONIAE
CLASSICS
GREEK
MUNICIPIAE
MUNICIPIA
CITIES

Although there have been numerous studies of individual cities or groups of cities, there has never been a study of the urbanism of the Roman world as a whole, meaning that we have been poorly informed not only about the number of cities and how they were distributed and changed over time, but also about their sizes and populations, monumentality, and civic status. This thesis provides a new account of the urbanism of the Roman world between 100 B.C. and A.D. 300. To do so, it draws on a combination of textual sources and archaeological material to provide a new catalogue of cities, calculates new estimates of their areas and uses a range of population densities to estimate their populations, and brings together available information about their monumentality and civic status for the first time. This evidence demonstrates that, although there were relatively few cities, many had considerable sizes and populations, substantial amounts of monumentality, and held various kinds of civic status. This indicates that there was significant economic growth in this period, including both extensive and intensive economic growth, which resulted from an influx of wealth through conquest and the intrinsic changes that came with Roman rule (including the expansion of urbanism). This evidence also suggests that there was a system that was characterised by areas of intense urban demand, which were met through an efficient system for the extraction of necessity and luxury goods from immediate hinterlands and an effective system for bringing these items from further afield. The disruption of these links seems to have put this system under considerable strain towards the end of this period and may have been sufficient to cause its ultimate collapse. This appears to have been in marked contrast to the medieval and early modern periods, when urbanism was more able to respond to changes in supply and demand.
A study of the square kilometre array low-frequency aperture array
Keywords: SKA
Beamformer
Square Kilometer Array
Beam former
Beamforming
Square Kilometre Array
Phased array
Aperture array
Interferometry
Beam forming

This thesis primarily comprises simulations of SKA1-Low, the low-frequency aperture array of the Square Kilometre Array (SKA) radio telescope. Simulations assess how different design specifications would affect the telescope's performance and ability to undertake one of its key science projects: observing the Epoch of Reionisation (EoR). The simulations are based on the previous baseline design of &Tilde; 260 000 dipole antennas in 1024 stations of 256 antennas each.
It is found that errors in the gain and phase of signals at each antenna can significantly affect observations, with the greatest impact at the lowest frequencies. The EoR signal will be detectable at limited redshifts with gain errors of 10% and phase errors of 6 degrees, however to ensure the systematic noise contribution from these errors is always weaker than the EoR signal between z &Tilde; 10 − 21 and spherical harmonic multipole coefficients l &Tilde; 102 − 104 , the gain and phase errors may need to be less than or equal to approximately 5 × 10−6 and less than or equal to approximately 3 × 10−4 degrees, respectively.
Alternative telescope layouts to the SKA1-Low baseline design of 1024 stations containing 256 antennas each are evaluated. Some telescope models which share antennas between stations, allowing stations to be formed in a flexible manner, are found to provide superior thermal noise sensitivity than the current design, but suffer greater detrimental effects from gain and phase errors when imaging.
The implementation of the digital signal processing of a station beamformer is also discussed. Calculations show that five or nine Field Programmable Gate Arrays (FPGAs) with specifications comparable to the Virtex UltraScale+ XCVU13P could be used to beamform a single 256-antenna SKA1-Low station, depending on the utilisation rate of the FPGAs and the number of channels required.
Mortality prediction and acuity assessment in critical care
Keywords: medical informatics
mortality prediction
severity of illness
critical care
intensive care unit
machine learning

Accurate mortality prediction in intensive care units (ICUs) allows for the risk adjustment of study populations, aids in patient care and provides a method for benchmarking overall hospital and ICU performance. ICU risk-adjustment models are primarily comprised of an integer severity of illness score which increases with increasing patient risk of mortality. First published in the 1980s, the improvements to these scores primarily consisted of increasing the dimensionality of the model, and hence also increasing their complexity. This thesis aims to improve upon these models. First, the field is surveyed and the major models for risk-adjusting critically ill patient cohorts are identified including the acute physiology score (APS) and the simplified acute physiology score (SAPS).
A key component of model performance is data preprocessing. The effect of preprocessing ICU data is quantified on a dataset of 8,000 ICU patients, and it is shown that after preprocessing to remove extreme values a logistic regression (LR) model performed competitively (AUROC of 0.8633) with the more complex machine learning model; a support vector machine (SVM) which had an AUROC of 0.8653. For validation, model development was repeated in a larger database containing over 80,000 patients admitted to 89 ICUs in the United States. Results were similar (AUROC of 0.8895 for the LR vs 0.8917 for the SVM) but showed the performance gain when using automated outlier rejection is less pronounced in well quality controlled datasets (0.8883 for LR without rejection). It is hypothesised from this that simpler models can perform competitively with more complicated models, while having a greatly reduced burden of data collection. A severity score is developed on the large multi-center database using a Genetic Algorithm and Particle Swarm Optimisation. The severity score, named the Oxford Acute Severity of Illness Score (OASIS), is shown to outperform the APS III (AUROC 0.837 vs 0.822) and perform competitively with APACHE IV when used as a covariate in a regression model (AUROC 0.868 vs 0.881). The severity score requires only 10 variables (58% as many as APS III), reducing the burden of quality control and data collection. These variables are routinely collected in critical care by continuous monitors and do not include comorbidities, diagnosis or laboratory measurements. The severity score is then externally evaluated in an American hospital and shown to discriminate well (AUROC 0.790 vs. 0.782 for the APS III) with excellent calibration. Finally, the severity score was evaluated in an English hospital and compared to other severity scores. OASIS again had excellent calibration and discrimination (AUROC 0.776 vs 0.750 for APS III) whilst requiring a much smaller number of variables. OASIS has many applications, including both simplifying data collection for studies and improving the risk assessment therein.
Between being and nothingness : sin in Jean-Paul Sartre
Keywords: nothingness
sin
existentialism
phenomenology of religion
Sartre

This thesis argues that Jean-Paul Sartre’s early philosophy retained a recognizable inheritance from the Christian doctrine of original sin. On the standard reading, Sartre’s most fundamental and attractive idea —the idea that brought him his reputation as ‘the philosopher of his generation’ —is freedom. But, as Sarah Richmond notes, Sartre’s interest in phenomenology ‘co-existed with and was an instrument for his wish to demonstrate the existence of human freedom, and his sense that the way to do this was by establishing an essential connection of consciousness with nothingness.’ Taking Being and Nothingness as its primary exegetical focus, this thesis argues that the early, anti-humanist Sartre retained a recognizable descendant of the Christian doctrine of original sin in his concept of le néant.
Previous scholars have noted the resemblance between Sartre’s and Augustine’s ontology: to name but one shared theme, both thinkers describe the human as the being through which nothingness enters the world. But no in-depth examination of this ‘resemblance’ has been made. Using historical, exegetical, and conceptual methods, my research demonstrates that Sartre’s intellectual formation prior to his discovery of phenomenology included theological elements which are often overlooked by Sartre scholars – especially in the English-speaking philosophical community, where his phenomenological influences receive greater attention.
The thesis therefore (i) outlines the French Augustinianisms by which, I argue, Sartre’s account of the human as ‘between being and nothingness’ was informed; in order to (ii) undertake a close reading of Being and Nothingness, which shows (a) that the psychological, epistemological, and ethical consequences of Sartre’s le néant closely resemble the consequences of its theological predecessor and (b) that his account of freedom can be read as an anti-theodicy; and finally (iii) to argue constructively that Sartre is a useful resource for contemporary hamartiology. In doing so it contributes to both Sartre scholarship and the theological sub-discipline of modern doctrine.
Preoperative symptom burden in the knee replacement population - the role of the Oxford knee score
Keywords: preoperative
patient reported outcome measures
knee replacement
symptoms

The Oxford Knee Score (OKS) represents a validated Patient Reported Outcome Score (PROM), routinely utilised following knee replacement (TKR). Healthcare commissioners have proposed its application as a threshold criterion to define eligibility for TKR, despite an absence of supporting evidence. This thesis explores the role of preoperative OKS, using local and national PROMs data, as a measure of symptom burden and highlights potential issues as a threshold criterion tool.
Examination of the preoperative OKS profile in three orthopaedic centres showed a normal distribution profile, and wide-ranging preoperative symptom burden. Some patients appeared to proceed to TKR with a seemingly minimal symptom burden, raising question about TKR selection criteria. Further analysis of national PROMs data confirmed wide variability in preoperative symptom burden prior to TKR to be common practice. Some variation existed between centres and individual surgeons, but patient level factors were a greater contributor, suggesting poor selection criteria may not be to blame. Case note analysis of a TKR cohort from a single centre identified that those with a high preoperative OKS still exhibited a significant symptom burden, remaining clinically justified for TKR. An appropriate consultation process was evident, rejecting inappropriate selection criteria as an explanation. Analysis of linked national pre- and postoperative OKS data showed that patients with highest preoperative OKS had best overall outcomes following TKR, despite minimal change in OKS. Preoperative OKS&LT;16 was associated with worse outcomes and minimal further benefit as OKS decreased.
Preoperative OKS alone may not encapsulate the true clinical indications for TKR. Utilisation of OKS-based thresholds, may exclude equally eligible patients, risking greater inequity and variation in TKR practice. Restricting TKR to those with the worst preoperative OKS may compromise subsequent outcomes. Its role as an indicator of preoperative symptom burden and potential eligibility for TKR should be used with extreme caution.
A metamaterial waveguide incorporating electric coupling for contactless data and power transfer
Keywords: electro-inductive wave
Capacitor-connected grids
electric coupling
data and power transfer channels
magneto-inductive wave
magnetic coupling

The background to this study is an effort to exploit a magneto-inductive waveguide (MIW) for near-field contactless data and power transfer applications. MIWs are almost purely magnetically coupled metamaterial waveguides whose coupling strengths can never exceed the limit of conservation of magnetic flux.
This study raises the hypothesis that the coupling strength limit of MIWs can be overcome by incorporating additional electric coupling into the structures; therefore, more strongly coupled metamaterial waveguides can be built and serve as contactless near-field communication channels with wider passbands and lower attenuations. The hypothesis was tested in this study by investigating a new variant of the metamaterial waveguide: the Capacitor-Connected Grid (CCG), in which additional electric coupling is introduced by connecting coupling capacitors over inter-element gaps between conventional MIW metallic loop resonators.
The study investigates the dispersion and attenuation characteristics of both one- (1-D) and two-dimensional (2-D) CCG devices, leading to a discussion on their potential uses in ultra- wideband (UWB) contactless near-field data transfer applications. A mixed coupling model calculating inter-element mixed coupling coefficients for arbitrarily configured CCG waveguides is derived based on the state-of-the-art, taking into account the shift of resonant frequency caused by electric coupling. The study also looks at terminal optimizations for 1-D CCG with a view to maximizing power transfer efficiency.
A highlight of this study is that a 1-D CCG demonstration device in theory should be able to achieve 192.4% fractional bandwidth, which exceeds the 20% requirement of a UWB channel by a factor of 9.6, and is only 1/10 of the minimum attenuation of an equivalent-sized MIW device. Similar communication characteristics have also been found at selected transmission paths on a 2-D CCG demonstration structure.
The results of this study on CCG waveguides verify the hypothesis that incorporating additional electric coupling into an almost purely magnetically coupled waveguide can improve its coupling strength and thereby achieve a communication channel with larger bandwidths and lower losses.
Understanding the large-scale dynamics of the interstellar medium in barred galaxies
Keywords: Barred galaxies
Gas dynamics
Spiral galaxies
Interstellar Medium: Kinematics &amp; Dynamics

We study the large-scale dynamics of the interstellar medium in barred galaxies. The interest in doing this is two-fold. On the one hand, the hydrodynamic flow is the source of many interesting physical phenomena, such as shocks and spiral arms. On the other hand, it is a powerful tool to constrain the characteristics of individual galaxies.
Approximately half of this thesis is devoted to understanding the general characteristics of the gas dynamics. There are two key ingredients. The first is ballistic closed orbits. We investigate the connection between closed orbits and the full hydrodynamic flow. We show how they also form the basis to explain bar-driven spiral arms. The second key ingredient is shocks. These can arise at the transition between different families of closed orbits, or when the spiral arms become too strong. Under certain conditions, shocks become hydrodynamically unstable and produce density fluctuations that may have an observational counterpart in the form of asymmetries in the Milky Way molecular gas distribution. We also explore systematically how the gas flow is affected by a change in the parameters that characterise the bar, such as its length, strength and pattern speed.
Through the study of the gas dynamics, inferences can be made about the structure of galaxies. We have compared our models with observations of the Milky Way. First, we revisit and refine the Binney et al (1991) model, one of the most successful models for the gas flow in the Galaxy. Then, we present new models that while preserving the good properties of the previous model can also correct its main shortcomings. These models can qualitatively account for most of the observational signatures of the Galactic bar and allow us to constrain its characteristics, such as its pattern speed, length and strength. However, we show that is difficult to find a model that accounts for all the important observational features simultaneously due to the high dimensionality of parameter space involved. We argue that automatic fitting method are necessary. To this end, we develop a new quantitative method to fit Milky Way longitude-velocity diagrams that is based on feature matching.
Foreign language learning in the age of the internet: A comparison of informal acquirers and traditional classroom learners in central Brazil
Keywords: out-of-classroom learning

Several recent studies (e.g., Benson and Chik, 2010; Sockett, 2014) suggest that as a result of changes in technology and the concomitant emergence of a globalized culture, highly effective out-of-class, informal English acquisition is becoming more common.
The present study compared high-level, well-motivated Central Brazilian classroom-trained learners (CTLs) with fully autonomous self-instructed learners (FASILs) of similar backgrounds. Using linguistic tests, a questionnaire and a structured interview, the study analysed group differences as well as individual differences in language proficiency, learner histories, behaviour, beliefs, and attitudes.
The key research question asked whether there existed, in more than rare circumstances, FASILs who attained levels of proficiency at least as high as highly-motivated, well-trained CTLs? Furthermore, if the knowledge and skills of FASILs were, in some respects, superior to those of CTLs, what variables accounted for the advantage?
FASILs significantly outperformed CTLs across a battery of linguistic tests measuring a range of knowledge and skills. Test results indicated that while CTLs tended to plateau at upper intermediate levels, FASILs generally improved through advanced levels, often achieving native-like levels of knowledge and use. The strongest contributing factor to proficiency was found to be self-determined motivation driven by a personalized relationship with English often marked by a transnational identity. The evidence suggests this type of motivation, significantly more associated with FASILs than CTLs, led users to engage deeply with the linguistic details of informal sources.
The findings challenge dominant paradigms in several fields of SLA which prioritize expert regulation over independent discovery and controlled, collaborative environments over real-world contexts of use entered into for personal reasons.
A hoped for consequence of this study is that SLA research and teaching practice will begin to recognize and promote rather than regulate or dismiss the unique learning arcs that more and more English learners experience in their everyday lives.
Towards a phonology of Hrusso Aka
Keywords: Hrusso Aka syllable structure
FUL model, Aditi Lahiri
Arunachali Languages
Endangered languages of India
Aka (Hruso)
Languages of Arunachal Pradesh
Hruso Aka
North-East Indian Languages
High Vowel Devoicing
Tone in Hrusso Aka
Hrusso Aka
Featurally Underspecified Lexicon
vowel devoicing
Sino-Tibetan Languages
Aka (Hrusso)
High vowel deletion
Tibeto-Burman Linguistics
syllable games

This thesis is a preliminary study of the phonology of Hrusso Aka, a minority language of Northeast India. Since Hrusso Aka is an understudied language, this general and broad study of Hrusso Aka phonology is aimed more at raising questions than providing answers, because it is not yet known what the questions are. The thesis has six chapters. In the first chapter I give general information on the Hrusso Aka language and discuss the data and the methodology. The second chapter will introduce the sound system of Hrusso Aka to the reader. I will be using the Featurally Underspecified Lexicon (FUL) model for the feature analysis of Hrusso Aka. In the third chapter I introduce this model and apply it to Hrusso Aka. The fourth chapter is dedicated to introducing some salient morpho-phonological processes such as high vowel devoicing, vowel harmony and vowel sequence constraints. The fifth chapter is on the Hrusso Aka syllable. There is also a brief excursus on stress, paving the way for further research on the Hrusso Aka prosody. The sixth chapter is on the Hrusso Aka consonant sequences. In this chapter I distinguish between various types of consonant sequences, discuss their phonological behaviour and raise pertinent issues for further research.