VictorJuiz/thesis huggingface dataset:
Direct injection gasoline engine particulate emissions

Direct fuel injection technology is increasingly being applied to the spark ignition internal combustion engine as one of the many actions required to reduce the CO2 emissions from road transport. Whilst the potential for CO2 reductions is compelling, the technology is not without disadvantages. Early examples typically emitted over an order of magnitude more Particulate Matter (PM) than vehicles with conventional spark ignition engines. Consequently, future revisions to European and North American exhaust emissions legislation are likely to regulate the particulate emissions from vehicles with direct injection gasoline engines. This thesis undertakes to investigate a) instrumentation capable of simultaneously resolving the number concentration and size distribution of particles in the 5-1000 nm size range and b) the factors affecting the PM emissions from spark ignition engines with direct fuel injection. The first objective is achieved by evaluation and comparison of a differential mobility spectrometer; photo-acoustic soot sensor; condensation particle counter and electrical low pressure impactor. To address the second question, a differential mobility spectrometer is applied to quantify the PM emissions from a number of direct injection gasoline engines, together with investigation of their dependence on various calibratable parameters, operating temperature and fuel composition. The differential mobility spectrometer showed good agreement with the other more established instruments tested. Moreover, it exhibited a faster time response and finer resolution in particle size. The number weighted size distribution of the PM emitted was typically lognormal with either one or two modes located between 20 and 100 nm. Chemical analysis of PM samples showed the presence of elemental carbon, volatile organic material and sulphates. Transient PM measurements enabled short time-scale events such as mode switching between homogeneous and stratified mixture preparation to be identified. PM number concentrations in stratified mode exceeded those in homogeneous mode by a factor of 10-100. Dynamometer based experiments showed that PM emissions increase for rich air fuel ratios, retarded fuel injection and advanced ignition events. They also demonstrated a strong dependence on fuel composition: the highest PM emissions were measured with an aromatic fuel, whereas blending alcohols such as methanol or ethanol tended to suppress PM emissions, particularly in the accumulation mode size range. These measurements are amongst the first of their kind and demonstrate the applicability of the differential mobility spectrometer to the measurement of ultra-fine particulate emissions from engines with direct fuel injection systems. Numerous explanations are put forward to describe the data obtained, together with suggestions for future work on PM control and abatement.

Keywords: engines
gasoline
particulate emissions
direct injection
Advisor: Stone, C
Stable isotope evidence for diet change in Roman and Medieval Italy: local, regional and continental perspectives

This thesis investigated dietary change in Roman and Medieval Europe c. AD 1-1500 using stable isotope analysis of humans and animals. Historical and archaeological data present two possibilities for how the social, political and economic changes of this period may have affected food practices. One argument suggests the population collapse and economic depression of the Early Medieval period increased the availability and consumption of meat. The counter- argument suggests that agricultural and economic patterns were constrained by local circumstances, and that no significant dietary change occurred.
This study combined local-scale isotopic analysis from central Italy with a meta-analysis of all available previously published data from Europe c. AD 1-1500. Mixed multi-level models were used to control for random inter-site variation, and to investigate the effect of multiple factors (Phase, Location, proximity to coast, Age, Sex, Species) on d13C and d15N. Within central Italy, 430 humans and 29 animals were analysed from eight archaeological sites dating from the 5th century BC to the 15th century AD. There were no significant differences through time, but coastal sites had significantly higher d13C and urban sites had significantly higher d15N. Across Europe, Early Medieval humans (c. AD 500-1000) had slightly but significantly lower d13C and d15N compared to Roman and Late Medieval individuals. This was the opposite of the effect expected due to increasing meat consumption at this time.
A number of complicating factors were discussed, including the effect of climate change, changing agricultural practices and uncertainty in estimating animal protein consumption based on d13C and d15N. When these effects are considered, the isotopic changes observed through time do not eliminate the possibility of increased meat consumption in the Early Medieval period. Nevertheless, the data presented from Roman Italy, and new models for estimating animal protein consumption, indicate that Roman historical sources may underestimate the dietary role of animal protein, and that therefore Roman and Early Medieval food production and consumption patterns were similar.

Advisor: Hedges, R
McCullagh, J
Numerical analysis of variational problems in atomistic interaction models

The present thesis consists of two parts. The first part is devoted to the analysis of discretizations of a class of basic electronic density functionals. In the second part we suggest and analyze Quasicontinuum Methods for an atomistic interaction potential that is based on a field.
We begin by formulating and analyzing a model for the study of finite clusters of atoms or localized defects in infinite crystals based on a version of the classical Thomas{Fermi{Dirac{von Weizs?acker density functional. We show that the resulting constrained optimization problem has a minimizer and we provide a careful analysis of the solvability of the associated Euler{Lagrange equation. Based on these results, and using tools from saddle-point theory and nonlinear analysis, we then show that a Galerkin discretization has a solution that converges to the correct limit (in the case of Dirichlet as well as periodic boundary conditions).
Furthermore, we investigate the issue of optimal convergence rates. Using appropriate dual problems, we can show faster convergence for the energy, the Lagrange multiplier of the underlying minimization problem, and the L2-errors of the solutions. We also look at the dependence of the density functional on the nucleus coordinates and show a convergence result for minimizing nucleus configurations.
These results are subsequently generalized to the case of discretizations with numerical integration. Existence and convergence of solutions, as well as optimal convergence rates can be established if quadrature rules of sufficiently high order are applied.
In the second part of the thesis we consider an atomistic interaction potential in one dimension given through a minimization problem, which gives rise to a field. The forces on atoms are in this case given by local expressions involving this field. A convenient feature of this model is the existence of a weak formulation for the forces, which provides a natural connection point for the coupling with a continuum model. We suggest Quasicontinuum-like coupling mechanisms that are based on a decomposition of the domain into an atomistic and a continuum region. In the continuum region we use an approximation based on the Cauchy{ Born rule. In the atomistic subdomain a version of the atomistic model with Dirichlet boundary conditions is applied. Special attention has to be paid to the dependence of the atomistic subproblem on the boundary and the boundary conditions. Applying concepts from nonlinear analysis we show existence and convergence of solutions to the Quasicontinuum approximation.

Keywords: 65N60
65Z05
65N25
Advisor: Süli, E
Christoph, O
An Investigation into the effects of topic and background knowledge of topic on second language speaking performance assessment in language proficiency interviews

This study explores, from a test validity perspective, the extent to which the two variables of topic and background knowledge of topic have an effect on spoken performance in language proficiency interviews. It is argued that in assessment contexts where topics are randomly assigned to test takers, it is necessary to demonstrate that topics of tasks and the level of background knowledge that test takers brings to these topics do not exert an undue influence on test results. Otherwise, a validity threat may be introduced to the test.
Data were collected from 82 Farsi speakers of English who performed on ten different topics, across three task types. Participants’ background knowledge of topics was elicited using self- report questionnaires while C-tests were used as a measure of general English language proficiency. Four raters assigned scores to spoken performances using rating scales. Semi- structured interviews were carried out with raters, upon completion of the rating process. A mixed- methods strategy of inquiry was adopted where findings from the quantitative analyses of score data (using Multi-Faceted Rasch Measurement, multiple regression and descriptive statistics) were synthesised with the results of the qualitative analyses of rater interviews and test takers’ content of speech in addressing the foci of the study.
The study’s main findings showed that the topics used in the study exhibited difficulty measures which were statistically distinct i.e. topics, within a given task type, could not be considered parallel. However, the size of the differences in topic difficulties was too small to have a large practical effect on scores. Participants’ different levels of background knowledge were shown to have a consistent, systematic and statistically significant effect on performance with low levels of background knowledge posing the highest level of challenge for test takers and vice versa. Nevertheless, these statistically significant differences in background knowledge levels failed to translate into practically significant differences, as the size of the differences were too small to have a large impact on performance scores. Results indicated that, compared to general language proficiency which accounted for approximately 60% of the variance in spoken performance scores, background knowledge only explained about 1-3% of the variance.
Qualitative analyses of data suggested lack of background knowledge to be associated with topic abandonment, disengagement from topic-related questions, and fewer opportunities for test takers to elaborate on topics. It was also associated with negative affective influence on test takers, particularly lower proficiency individuals. Taken together, the findings have theoretical, methodological and practical implications for second language speaking performance assessment.

Keywords: language testing
second language speaking assessment
Rasch analysis
Advisor: Vanderplank, R
Walter, C
Vertical transport through n-As/p-GaSb heterojunctions at high pressures and magnetic fields

The conduction band of InAs lies lower in energy than the GaSb valence band. In order to preserve continuity of the Fermi level across the interface, charge transfer takes place resulting in a confined quasi two dimensional electron gas (2DEG) in the InAs and a confined quasi two dimensional hole gas (2DHG) in the GaSb.
This study is an investigation into the vertical transport in an n-InAs/p-GaSb single heterojunction (SHET). Application of a forward bias (InAs negative with respect to GaSb) increases the 2DEG and 2DHG concentrations and, therefore, their confinement energies. Eventually a critical bias is reached where the electron confinement energy moves above the hole confinement energy (the theoretical voltage induced semimetal/semiconductor transition Vc). Any subsequent increase in voltage is expected to result in a current decrease, and a region of negative differential resistance (NDR) should occur.
The SHET can be grown with two distinct interface types, 'InSb-like' and 'GaAs-like'. This in turn affects the vertical transport characteristics of each type. Experimental IV traces at various pressures are compared with the corresponding results from sophisticated self-consistent band profile calculations taking into account band mixing effects for the first time through a k.p theory framework. Experimental IV traces of the SHETs under a magnetic field parallel to the interface are also compared with results from calculations that take into account the coupling of the growth and in-plane electron and heavy hole motions. Both sets of analysis support earlier conclusions that NDR occurs after Vc for both interfaces, and that each interface supports a different conduction mechanism.
Evidence of multiple phonon processes occurring in both sample types is observed for the first time and is proposed to reconcile the above experimental observations with theory. This data is found to offer explanations for a number of other observations.
Field perpendicular to the interface leads to the observation of features beyond the NDR region in both sample types. In samples with an 'InSb-like' interface, applying additional hydrostatic pressure leads to very strong features beyond the main NDR. Through a complex self-consistent decoupled model taking into account electrons and heavy holes, all these features are proposed to be due to a filling of an integer number of Landau levels. The band profile is predicted to alter dramatically at this point. The same model explains the observation of weaker features at 1 bar at high fields (~ 40T).
A variation of NDR position is found with a rotation of an-plane field.
Implicit concept formation

This thesis provides a conceptual and empirical analysis of implicit concept formation. A review of concept formation studies highlights the need for improving existing methodology in establish- ing the claim for implicit concept formation. Eight experiments are reported that address this aim. A review of theoretical issues highlights the need for computational modelling to elucidate the nature of implicit learning. Two chapters address the feasibility of different exemplar and Connectionist models in accounting for how subjects perform on tasks typically employed in the implicit learn- ing literature.
The first five experiments use a concept formation task that involves classifying "computer people" as belonging to a particular town or income category. A number of manipulations are made of the underlying rule to be learned and of the cover task given subjects. In all cases, the knowledge underlying classification performance can be elicited both by free recall and by forced choice tasks.
The final three experiments employ Reber's (e.g., 1989) grammar learning paradigm. More rigorous methods for eliciting the knowledge underlying classification performance are employed than have been used previously by Reber. The knowledge underlying clas- sification performance is not elicited by free recall, but is elicited by a forced-choice measure. The robustness of the learning in this paradigm is investigated by using a secondary task methodol- ogy. Concurrent random number generation interferes with all knowledge measures.
A number of parameter-free Connectionist and exemplar models of artificial grammar learning are tested against the experimental data. The importance of different assumptions regarding the coding of features and the learning rule used is investigated by determin- ing the performance of the model with and without each assumption. Only one class of Connectionist model passes all the tests. Fur- ther, this class of model can simulate subject performance in a different task domain.
The relevance of these empirical and theoretical results for understanding implicit learning is discussed, and suggestions are made for future research.

Advisor: Broadbent, D
Berry, D
An investigation of anion binding by acyclic metal-centred receptors

This thesis reflects two main aims. Firstly, the synthesis and characterisation of a number of potential anion receptors was undertaken and their anion binding properties were assessed. In so doing, a second aim was fulfilled, namely a comparison of the various methods of detecting the bound anion, and quantifying the binding strength. Four techniques appear in this thesis; 1H nuclear magnetic resonance, UV-visible spectroscopy, electrochemistry and luminescent emission. Quantitative titrations were performed and, where possible, stability constants estimated.
Chapter One provides an introduction to some of the themes of molecular recognition and provides a brief overview of the literature associated with anion recognition. A Prologue describes the design of the receptors studied; they all incorporate a metal centre and appended amide groups which provide sources of hydrogen bonding. The molecules are mostly cationic and a combination of positive charge and hydrogen bonding constitutes the binding interaction.
Chapter Two is concerned with receptors based on cobalticinium, [Cp2Co] + . A number of receptors are presented and are found to bind anions with stability constants typically in the range of 500-1000 dm3mol-1 . Receptors involving more than one cobalticinium centre are found to bind much more strongly and, furthermore, variations in functional groups appended close to the proposed coordination site impart selectivity; dihydrogen phosphate is bound more strongly than chloride. It is also found that different techniques give different stability constants and comment is made on this phenomenon.
Chapter Three examines the role of positive charge in anion binding and describes the synthesis and coordination properties of several neutral receptors. These molecules retain hydrogen bonding sites, and it is found that this is sufficient to bind anions, but the strength of the interaction is greatly reduced.
Chapter Four introduces another system, based on RuL(bpy)22+ , where L is a 4,4'-amide disubstituted bpy. The strength of binding is an order of magnitude greater than the cobalticinium systems as detected by several methods including emission studies, which are very sensitive. Comparison with a neutral, rhenium-based receptor is made. A dihydrogen phosphate-selective luminescent sensor is also presented.
The Epilogue identifies areas for future research. Specialised introductions and summaries are found at the beginning and end of each chapter.

Advisor: Beer, P
Capital punishment, abolition and Roman Catholic moral tradition

The last fifty years have seen a turn in the Catholic Church's public attitude toward capital punishment. From openly defending the right of the state to kill malefactors, the Church has become an outspoken opponent. What accounts for this? How can it be reconciled with Catholic tradition? Should the current teaching be called a 'development of doctrine'? Can we expect further change? These questions shape this thesis.
The work is divided into three parts comprising a total of eight chapters. Part I undertakes a detailed exegesis of the death penalty teaching of the Catechism of the Catholic Church (1997). I conclude that the text, while not explicitly stating that the death penalty is in itself wrong, lays down premises which when carried to their logical conclusions, yield just such a conclusion. This conclusion is checked and confirmed by the fundamental moral reasoning found in the papal encyclicals Evangelium Vitae and Veritatis Splendor.
In light of this conclusion (what I call the new position), Part II asks the question: may the Church, constrained by sound biblical interpretation and dogmatic tradition, legitimately teach in a definitive way that capital punishment is per se wrong? This is a question which concerns the development of doctrine. Before it can be answered the Church's traditional teaching needs to be precisely formulated so that it can be placed in juxtaposition to the new teaching. An analysis of statements throughout ecclesiastical history is therefore undertaken and what we might call the cumulative consensus of ecclesiastical writers on capital punishment is formulated. The authoritative nature of this teaching is analyzed to determine what kinds of developments it admits and excludes. Judging its nature admits of a development like the one described in Part I, models are proposed to explain modes by which it might be understood to be developing. Finally, a systematic and philosophically consistent account of the new position is proposed and its implications for other teachings in the Church's tradition of 'justifiable violence' is examined.
A philological commentary on Tacitus, Annals 14, 1-54

The Commentary deals only with stylistic and linguistic matters. Textual problems are sometimes discussed, but only when they can be illuminated by points of usage. Diverse subjects are treated, but certain themes predominate.
Many of the notes are concerned with the history and usage of certain words and stylistic devices down to the end of the first century A.D. Tacitus' originality and idiosyncrasies, and his indebtedness both to contemporary developments in educated usage and to the historiographical tradition, are pointed out. Archaisms, poeticisms, and words of high style are differentiated from words current among the educated classes. Tacitus' vocabulary is compared in artificiality with that of previous historians and other archaising writers of the early Empire. The Controversiae and Suasoriae of the Elder Seneca, the Institutio Oratoria of Quintilian, and the Declamations ascribed to Quintilian have been taken as evidence for the ordinary educated usage of the period.
[Abstract continues in thesis ...]

Keywords: Stylistic change
Annals
Tacitus
Advisor: Ogilvie, R
Role of Base and nucleotide excision repair pathways in processing of clustered DNA lesions induced by ionising radiation

Ionising radiation (IR) induces a wide spectrum of lesions in DNA, including double- and single-strand breaks, abasic (AP) sites and a variety of base lesions. IR-induced damage to DNA can range from simple, isolated lesions to clustered DNA damage in which multiple lesions are formed, usually within a single helical turn of the DNA. Individual lesions within a cluster are recognised by repair enzymes of the base excision repair (BER) pathway, however, clustered DNA damage may be recognised as a bulky lesion and be processed by nucleotide excision repair (NER). Additionally, the presence of other closely spaced lesions may affect the rate and fidelity of DNA repair and, in doing so, may contribute to the harmful effects of ionising radiation. The aim of this study is to gain further understanding of the repairability of clustered DNA damage and the effects of multiple lesions on cellular repair systems. 7, 8-dihydro-8-oxoguanine (8-oxoG), thymine glycol (Tg), AP sites and single-strand breaks (SSB), some of the most frequently formed IR-induced DNA lesions, were employed in synthetic oligonucleotides to model various types of clustered lesions and their repairability was studied using purified base excision repair enzymes and cell extracts. It was revealed that BER is the major repair system involved in the processing of clustered DNA lesions, and that some clustered lesions are repaired with decreased efficiency. Both the composition of lesions in a cluster and the positioning of the various lesions determine their repairability by base excision repair enzymes.