VictorJuiz/thesis huggingface dataset:
Radiotherapy dose-fractionations and outcomes in cancer patients
Keywords: radiotherapy dose-fractionation
PUBLIC HEALTH ENGLAND
lung cancer
epidemiology
radiotherapy
META-ANALYSIS
breast cancer
Radiation
THAMES VALLEY
CANCER REGISTRATION
cancer survival

Radiotherapy cures many cancers, but the optimum total doses and fractionations used to treat different cancer types remain uncertain. While conventional fractionation (≈2 Gy per fraction) is common in many countries, UK practice has been highly variable.
This thesis compared different curative-intent radiotherapy dose-fractionations used in non-small cell lung and breast cancer. These two cancers together make up over a quarter of UK cancer incidence and mortality, and radiotherapy can increase cure rates of both cancers.
Two studies were conducted: (A) A meta-analysis of randomised radiotherapy trials in non-small cell lung cancer and (B) A cohort study of non-small cell lung and breast cancer radiotherapy in the Thames Valley.
For the meta-analysis, a systematic search was conducted. Eligible studies were randomised comparisons of two or more radiotherapy regimens. Median survival ratios were calculated for each comparison and pooled. 3,795 patients in 25 randomised comparisons of radiotherapy dose were studied. When radiotherapy was given alone, the higher dose within-trial resulted in increased survival (median survival ratio 1.13, 95% confidence interval 1.04-1.22). When radiotherapy was given with concurrent chemotherapy, the higher dose within-trial resulted in decreased survival (median survival ratio 0.83, 95% confidence interval 0.71-0.97).
For the cohort study, multiple Public Health England data sources were combined to obtain information on radiotherapy, patient characteristics, and outcomes. Multivariable Cox regressions were conducted separately by cancer site. 324 non-small cell lung, 8,879 invasive breast, and 477 ductal carcinoma in situ patients were studied. In analyses of both non-small cell lung and invasive breast cancer, increasing radiotherapy dose was associated with improved survival in some treatment centres, while in other centres the opposite was true. These opposite trends by treatment centre were unlikely to be explained by chance, and they suggest that differences in patient selection were driving results. There were insufficient events among ductal carcinoma in situ patients to assess associations.
Findings from the meta-analysis support consideration of further radiotherapy dose escalation trials, making use of modern methods to reduce toxicity. Findings from the cohort study suggest that it is not possible to use observational studies to examine causal effects of radiotherapy dose-fractionation. This thesis therefore shows the continued importance of conducting sufficiently large randomised trials to ascertain optimal dose-fractionation in radiotherapy.
Density, temperature and magnetic field measurements in low density plasmas
Keywords: Plasma
Laser
Verdet crystal
Magnetic field measurements
Radio Frequency Discharge
gamma regime
supersonic jets

Low density plasmas are found throughout the known universe. Therefore, accurate diagnostic methods have implications for our understanding of a variety of topics, ranging from star formation to the semi conductor industry.
Low density plasmas are ubiquitous in the material processing industry. However, measurements of the electron temperature and density, two of the most fundamental plasma properties, are not straightforward. In the laboratory, we create a low density, radio frequency, helium plasma with a bi-Maxwellian electron distribution, similar to those found in the semiconductor processing industry. We use optical emission spectroscopy to perform a non invasive measurement of the plasma conditions. We compare this to measurements obtained using a Langmuir probe, a commonly used invasive diagnostic. The optical emission spectroscopy is found to be insensitive to electron density but good agreement is found between the two techniques for values of the temperature of the hot electron component of the bi-Maxwellian.
Plasmas created with high-intensity lasers are able to recreate conditions similar to those found during astrophysical events. This development has led to these condi- tions being explored in laboratories around the world. An experiment was performed at the Rutherford Appleton Laboratory in Didcot, UK, investigating the properties of supersonic turbulent jets. For the first time a magneto-optic probe was used to measure the magnetic field in a low-density supersonic turbulent plasma. The re- sults were compared to measurements taken using a magnetic-induction probe. Good agreement was found between measurements of the magnetic field strength within the plasma; however, the magnetic power spectra di↵er. We attribute this to the dif- ference in integration length between the two measurements. Statistical properties of the velocity field are inferred from the magnetic field measurements, which compare favourably to astrophysical observations and hydrodynamic simulations.
Essays on firms and employee compensation
Keywords: Wages
Pensions
Market Power
Employment
Compensation
Start-ups

This DPhil thesis is a collection of three empirical papers that study the role of firms in the UK labour market. Each chapter focuses on firms at different points in their lifecycle.
Young firms are an engine of job creation but little is known about the quality of the jobs that they offer. In Chapter 1, I use a matched employer-employee dataset to study how starting wages and lifecycle earnings of employees differ between young and mature firms. I find that young firms pay a small premium to new hires, but subsequent wage growth is better at mature firms, both within continuing job matches and when individuals change jobs. Crucially, highly-paid and stable jobs at young firms have become increasingly rare over time, as young firms themselves have become less likely to survive and attain high productivity levels—both in absolute terms and relative to mature firms over the same period. Policies that aim to stimulate job growth by encouraging the formation of new firms should therefore pay close attention to the types of firms that form.
Chapter 2 asks what determines the proportion of a firm’s income that workers receive as compensation. I use longitudinal firm data from a period of substantial labour share variation to understand the firm-level determinants of the labor share of income—a question that has typically only been addressed with country- and sector-level data. Estimating a dynamic model using GMM, I find that firms with greater market power and a higher ratio of capital to labour allocate a smaller proportion of their value added to workers. Testing the impact of tangible and intangible capital on low- and high-wage firms leads to conclusions consistent with the hypothesis of capital-skill complementarity. Overall, the results suggest that firm-level drivers play a key role in the evolution of the aggregate labour share, which has declined significantly since the 1970s.
Chapter 3 co-authored with Brian Bell, focuses on mature firms and asks how wages at such firms respond to idiosyncratic firm-level cost shocks. We create a unique dataset that links longitudinal data on workers’ compensation to the unexpected costs related to firms’ legacy defined benefit pension plans. We show that firms are able to share the burden of such costs when a significant share of their workers are current or former members of the plan. We also find that firms that respond to deficits by closing down the pension plans effectively reduce the total compensation of plan members. These results point to significant frictions in the labour market, which we show are a direct result of the pension arrangement that workers have. Yet closing schemes has an implicit cost for firms, since it reduces the frictions that workers face, and increases mobility.
Quantum Hall Edges Beyond Luttinger Liquid
Keywords: Conformal Field Theory
Quantum Hall Edges

We consider a series of problems regarding quantum Hall edges, focusing on both dynamics and the mathematical structure of edge states.
We begin in Chapter 3 with a limiting case of the Laughlin state placed in a very steep confining potential, but which is weak compared to the interactions. We find that the eigenstates have a Jack polynomial structure and an energy spectrum which is extremely different from the well-known Luttinger liquid edge.
In Chapter 5 we analyse the inner products of edge state wavefunctions, using an effective description given by a large-N expansion ansatz proposed by J. Dubail, N. Read and E. Rezayi, PRB 86, 245310 (2012). As noted by these authors, the terms in this ansatz can be constrained using symmetry, a procedure we perform to high orders. We then check the conjecture by calculating overlaps exactly for small system sizes and comparing the numerics with our high-order expansion to find excellent agreement.
Finally, Chapter 6 considers the behaviour of quantum Hall edges close to the Luttinger liquid fixed point that occurs in the low energy, large system limit. We construct effective Hamiltonians using a local field theory description and then consider the effect of bulk symmetries on this edge. The symmetry analysis produces remarkable simplifications which allow for very accurate descriptions of the low-energy edge physics even relatively far away from the Luttinger liquid fixed point.
Investigating the potential for improving the accuracy of weather and climate forecasts by varying numerical precision in computer models
Keywords: Efficiency
Forecasting
Climate change
Reduced Precision
Error growth
Surface Quasi-Geostrophic
Inexact hardware
Emulator
Lorenz '96
Open IFS
Numerical Precision
Weather

Accurate forecasts of weather and climate will become increasingly important as the world adapts to anthropogenic climatic change. Forecasts' accuracy is limited by the computer power available to forecast centres, which determines the maximum resolution, ensemble size and complexity of atmospheric models. Furthermore, faster supercomputers are increasingly energy-hungry and unaffordable to run.
In this thesis, a new means of making computer simulations more efficient is presented that could lead to more accurate forecasts without increasing computational costs. This 'scale-selective reduced precision' technique builds on previous work that shows that weather models can be run with almost all real numbers represented in 32 bit precision or lower without any impact on forecast accuracy, challenging the paradigm that 64 bits of numerical precision are necessary for sufficiently accurate computations. The observational and model errors inherent in weather and climate simulations, combined with the sensitive dependence on initial conditions of the atmosphere and atmospheric models, renders such high precision unnecessary, especially at small scales. The 'scale-selective' technique introduced here therefore represents smaller, less influential scales of motion with less precision. Experiments are described in which reduced precision is emulated on conventional hardware and applied to three models of increasing complexity. In a three-scale extension of the Lorenz '96 toy model, it is demonstrated that high resolution scale-dependent precision forecasts are more accurate than low resolution high-precision forecasts of a similar computational cost. A spectral model based on the Surface Quasi-Geostrophic Equations is used to determine a power law describing how low precision can be safely reduced as a function of spatial scale; and experiments using four historical test-cases in an open-source version of the real-world Integrated Forecasting System demonstrate that a similar power law holds for the spectral part of this model. It is concluded that the scale-selective approach could be beneficially employed to optimally balance forecast cost and accuracy if utilised on real reduced precision hardware.
The unmanned revolution: how drones are revolutionising warfare
Keywords: Unmanned Aerial Vehicle
Technology and Warfare
British Armed Forces
Bundeswehr
Military Technology
Revolution in Military Affairs
Drones

Are drones revolutionary? Reading about military unmanned aerial vehicles (UAVs), or ‘drones’, one could be led to believe that drones are a revolutionary technology, set to fundamentally change warfare. Their fast proliferation, the association with Science Fiction, combined with the secrecy that surrounds drone use has led many to conclude that the ‘Unmanned Revolution’ is upon us.
This thesis studies the Unmanned Revolution. It develops a framework based on the concept of the ‘Revolution in Military Affairs’ and applies it to the study of three countries’ drone uses and integration into their armed forces. It furthermore explores the role that the designation as revolutionary has played for the integration and use of UAVs in the United States, Germany, and the United Kingdom.
It shows that drones have proven their worth in military operations and compares the three countries’ experiences. This thesis’ detailed assessment of how the different countries have adopted drones and what implication this adoption has had, makes it a work of reference, in particular with regard to the German and British case studies.
Assessing five types of changes – operational, doctrinal, strategic, organisational, and social and societal – this thesis argues that the most fundamental, and possibly revolutionary, change caused by military drones is social, namely, the fundamentally changed experience of war by combatants. In addition, it highlights country-specific changes.
It concludes that the designation of drones as revolutionary has had an important impact in one country, Germany, although in the opposite way than initially expected. Namely, the intense debate around UAVs has hindered drone procurement and doctrinal thinking. In the other two countries, the Unmanned Revolution narrative was less prevalent and hence less influential.
As drones are proliferating globally, I hope my thesis can be of use to policy-makers, military decision-makers as well as researchers worldwide.
Efficient Supervision for Robot Learning via Imitation, Simulation, and Adaptation
Keywords: Imitation Learning
Domain Adaptation
Inverse Reinforcement Learning
Transfer Learning
Autonomous Driving
Mobile Robotics

In order to enable more widespread application of robots, we are required to reduce the human effort for the introduction of existing robotic platforms to new environments and tasks. In this thesis, we identify three complementary strategies to address this challenge, via the use of imitation learning, domain adaptation, and transfer learning based on simulations. The overall work strives to reduce the effort of generating training data by employing inexpensively obtainable labels and by transferring information between different domains with deviating underlying properties.
Imitation learning enables a straightforward way for untrained personnel to teach robots to perform tasks by providing demonstrations, which represent a comparably inexpensive source of supervision. We develop a scalable approach to identify the preferences underlying demonstration data via the framework of inverse reinforcement learning. The method enables integration of the extracted preferences as cost maps into existing motion planning systems. We further incorporate prior domain knowledge and demonstrate that the approach outperforms the baselines including manually crafted cost functions.
In addition to employing low-cost labels from demonstration, we investigate the adaptation of models to domains without available supervisory information. Specifically, the challenge of appearance changes in outdoor robotics such as illumination and weather shifts is addressed using an adversarial domain adaptation approach. A principal advantage of the method over prior work is the straightforwardness of adapting arbitrary, state-of-the-art neural network architectures. Finally, we demonstrate performance benefits of the method for semantic segmentation of drivable terrain.
Our last contribution focuses on simulation to real world transfer learning, where the characteristic differences are not only regarding the visual appearance but the underlying system dynamics. Our work aims at parallel training in both systems and mutual guidance via auxiliary alignment rewards to accelerate training for real world systems. The approach is shown to outperform various baselines as well as a unilateral alignment variant.
Controls on fracture abundance in gently deformed carbonates
Keywords: Fractures
Carbonate reservoirs
Arabia
Stress
Arab Reservoirs

Fractures can profoundly affect the capacity of carbonate reservoirs to store and permeate fluids, depending on the properties and abundance of fractures. Fractures exist abundantly in carbonate outcrops; however, their abundance in subsurface carbonates is obscure because of the data shortages and uncertainties about the factors that drive fracturing in sedimentary basins. The objective of this research is twofold. The first is to study abundance of fractures in gently deformed carbonates, which were generally overlooked. The second is to address measuring fracture abundance using electrical borehole imaging, which is the mostly used method to describe reservoir fractures. Fractures were studied from areas in the gently folded and shallowly (less than 2 km depth) buried interiors of the Arabian Platform. The study areas include outcrops and reservoirs of the Late Jurassic Arab carbonates in the sprawling homocline of Central Arabia and a low-relief dome in Eastern Arabia. The Cenozoic Rus carbonates in the dome outcrops were also studied. Fracture abundance was measured from the outcrops using scanlines and from the reservoirs using core and borehole images of extended-reach drilling. Many systematic properties were drawn on mineralization, orientation, and abundance of fractures. The fractures were found to be opening mode, mostly barren, and exist with subvertical dips, and some regional trends. The fractures display significantly differing ranges of abundance that were controlled by the subtle structural bending of the dome and homocline, carbonate lithofacies, and paucity of fracture mineralization. The borehole imaging was found to significantly lower fracture abundance. The detection of fractures was subject to several factors including size of fracture widths, nature of fracture roughness, and present-day stress field. The results have implications for modeling of fracture systems and tectonic regimes. For example, finding that fracture abundance varies drastically in such gently deformed regions indicates that carbonates are very sensitive to fracturing processes. Moreover, the borehole imaging limitations influence the models of fracture abundance and orientations, which are often used to deduce paleo tectonic regimes and present-day geodynamics in carbonate reservoirs.
Completing the global inventory of plants – species discovery and diversity
Keywords: taxonomy
species distributions
species discovery
conservation

To complete an online world Flora by 2020 rapid progress is required towards understanding the taxonomy and distributions of the world’s plants. This ambitious target set by the Global Strategy for Plant Conservation is hampered by two facts; first, many species of seed plant remain poorly known and second, the process of improving taxonomy and discovering species is not well understood. Here I investigate in detail the taxonomy and process of species discovery in a genus of tropical plants, Aframomum by examining specimens, taxonomic literature and authors of specimen determinations. I demonstrate that &GT;50% of Aframomum specimens did not have the correct name prior to a recent comprehensive revision, that the number of specimens in herbaria doubled between 1970 and 2000, and that these results are also found in other taxa. I deconstruct the process of ‘species discovery’ by identifying four key events: Initial collection, publication, conservation assessment, and distribution mapping. The time lags between the initial collection and completion of a) an accurate conservation assessment (101 years) and b) a comprehensive distribution map (115 years) demonstrate that many seed plant species published in the last 100 years are not fully understood. This is partly due to the fact that most species protologues (&GT;90%) cite too few specimens at publication to produce an accurate conservation assessment. Furthermore, I explore variation in species’ distribution patterns over time, taking account of specimen misidentification. Taken together the thesis identifies the lack of taxonomic capacity to efficiently deal with the tremendous influx of specimens since 1970, the poor current state of taxonomic knowledge of many taxa, and three significant time lags in the process of species discovery. Focused taxonomic effort is required for the successful completion of a world online Flora with conservation assessments to meet the 2020 GSPC target.
Learning about academic writing through holistic peer assessment
Keywords: feedback
peer review
peer assessment
English Studies
self-regulated learning
university students
task perceptions
assessment criteria
academic writing
metacognition

While there is a consensus among researchers that assessment should and can serve learning, there is less understanding of how it supports learning at a fine-grained level. This thesis uses design-based research to investigate the role of comment-only, holistic peer assessment in writing development. The theory of action synthesises Sadler’s accounts of learning through assessment (1989, 2010) with Winne and Hadwin’s (1998, 2008) model of self-regulated learning. It is theorised that participating in peer assessment helps students to develop evaluative expertise, which in turn enriches task perceptions, metacognitive standards and ultimately large-scale adaptation: the changes students employ in subsequent essays. Drawing on the theory of action, I designed a series of workshops for first-year English Literature students learning to write examination essays. The thesis reports on the first of two iterations. 21 participants assessed and discussed example essays; criteria were not pre-determined but emerged from discussion of four examples. Students then wrote a timed essay, assessed three peer pieces and received three reviews. A range of data was generated during the workshops, including written comments, reflections and questionnaires. Ten case study writers also took part in pre- and post-workshops writing tasks, think-aloud protocols and interviews.
To trace the development of students’ evaluative expertise, I coded inductively students’ talk and comment about writing. Visualising the connections between emergent codes reveals writing quality as a complex web of criteria, with the essay question at the centre. There was a strong overlap between the official Faculty assessment criteria and the codes emerging from student data. However, students also frequently commented on procedural aspects of writing such as introductions and conclusions, which are left tacit or latent in Faculty criteria. Post-workshops, students’ own metacognitive standards became increasingly reader-oriented and question-focussed, and these procedural aspects of writing drove the adaptations they made to their approach. I use rich, in-depth case study data to trace how, why, and when students made such adaptations. I also examine the role of peer feedback, which rather than offering new information, often verified or complemented the judgements students formed of their own writing during the workshops. The thesis thus illuminates processes involved in learning through assessment. It also shows that peer assessment is a practicable way of developing within the discipline both evaluative expertise and writing, which are key to lifelong learning.