VictorJuiz/thesis huggingface dataset:
Advancing large scale object retrieval

The objective of this work is object retrieval in large scale image datasets, where the object is specified by an image query and retrieval should be immediate at run time. Such a system has a wide variety of applications including object or location recognition, video search, near duplicate detection and 3D reconstruction. The task is very challenging because of large variations in the imaged object appearance due to changes in lighting conditions, scale and viewpoint, as well as partial occlusions.
A starting point of established systems which tackle the same task is detection of viewpoint invariant features, which are then quantized into visual words and efficient retrieval is performed using an inverted index. We make the following three improvements to the standard framework: (i) a new method to compare SIFT descriptors (RootSIFT) which yields superior performance without increasing processing or storage requirements; (ii) a novel discriminative method for query expansion; (iii) a new feature augmentation method.
Scaling up to searching millions of images involves either distributing storage and computation across many computers, or employing very compact image representations on a single computer combined with memory-efficient approximate nearest neighbour search (ANN). We take the latter approach and improve VLAD, a popular compact image descriptor, using: (i) a new normalization method to alleviate the burstiness effect; (ii) vocabulary adaptation to reduce influence of using a bad visual vocabulary; (iii) extraction of multiple VLADs for retrieval and localization of small objects. We also propose a method, SCT, for extremely low bit-rate compression of descriptor sets in order to reduce the memory footprint of ANN.
The problem of finding images of an object in an unannotated image corpus starting from a textual query is also considered. Our approach is to first obtain multiple images of the queried object using textual Google image search, and then use these images to visually query the target database. We show that issuing multiple queries significantly improves recall and enables the system to find quite challenging occurrences of the queried object.
Current retrieval techniques work only for objects which have a light coating of texture, while failing completely for smooth (fairly textureless) objects best described by shape. We present a scalable approach to smooth object retrieval and illustrate it on sculptures. A smooth object is represented by its imaged shape using a set of quantized semi-local boundary descriptors (a bag-of-boundaries); the representation is suited to the standard visual word based object retrieval. Furthermore, we describe a method for automatically determining the title and sculptor of an imaged sculpture using the proposed smooth object retrieval system.

Keywords: image search
visual search
object retrieval
Advisor: Zisserman, A
An analysis of fretting fatigue

This thesis describes a series of fretting fatigue experiments carried out under closely controlled conditions of partial slip. These experiments confirm the existence of a size effect whereby the fretting fatigue life of an aluminium alloy is shown to vary with contact size.
The configuration chosen, of cylindrical fretting pads contacting a plane specimen is amenable to classical stress analysis and the surface tractions between the contacting bodies are derived. The effects of tension in the specimen, finite specimen thickness, differing elastic constants, and surface roughness are all investigated and incorporated into the analysis where appropriate. A technique is then developed to calculate stress intensity factors for plane cracks growing under the contact load at an arbitrary angle to the free surface.
The analysis is then applied to the experimental results and three possible explanations for the size effect are proposed, based on statistical effects, crack arrest, and crack initiation. These are examined in the light of the experimental evidence and it is proposed that the variation of fatigue life with contact size is due to an increase in the amount of fretting damage above a threshold level for crack initiation.
A composite parameter is chosen to characterise the severity of fretting conditions and this is shown to describe the experimental results accurately. Finally, the use of this parameter in design calculations is discussed.

Advisor: Hills, D
Coherent spin dynamics of radical pairs in weak magnetic fields

The outcome of chemical reactions proceeding via radical pair (RP) intermediates can be influenced by the magnitude and direction of applied magnetic fields, even for interaction strengths far smaller than the thermal energy. Sensitivity to Earth-strength magnetic fields has been suggested as a biophysical mechanism of animal magnetoreception and this thesis is concerned with simulations of the effects of such weak magnetic fields on RP reaction yields.
State-space restriction techniques previously used in the simulation of NMR spectra are here applied to RPs. Methods for improving the efficiency of Liouville-space spin dynamics calculations are presented along with a procedure to form operators directly into a reduced state-space. These are implemented in the spin dynamics software Spinach.
Entanglement is shown to be a crucial ingredient for the observation of a low field effect on RP reaction yields in some cases. It is also observed that many chemically plausible initial states possess an inherent directionality which may be a useful source of anisotropy in RP reactions.
The nature of the radical species involved in magnetoreception is investigated theoretically. It has been shown that European Robins are disorientated by weak radio-frequency (RF) fields at the frequency corresponding to the Zeeman splitting of a free electron. The potential role of superoxide and dioxygen is investigated and the anisotropic reaction yield in the presence of a RF-field, without a static field, is calculated. Magnetic field effect data for Escherichia coli photolyase and Arabidopsis thaliana cryptochrome 1, both expected to be magnetically sensitive, are satisfactorily modelled only when singlet-triplet dephasing is included.
With a view to increasing the reaction yield anisotropy of a RP magnetoreceptor, a brief study of the amplification of the magnetic field experienced by a RP from nearby magnetite particles is presented.
Finally in a digression from RPs, Spinach is used to determine the states expected to be immune from relaxation and therefore long-lived in NMR experiments on multi-spin systems.

Keywords: spin dynamics
magnetoreception
spin chemistry
magnetic field effects
NMR spectroscopy
EPR spectroscopy
Advisor: Peter, H
Fatal distraction: does the Texas capital sentencing statute discourage the consideration of mitigating evidence?

Whether the capital sentencing statute in Texas provides a vehicle for jurors to give effect to mitigation evidence has been a critical factor when the United States Supreme Court has sought to determine its constitutionality. Unlike the majority of other American jurisdictions which maintain capital punishment as a penalty, Texas utilizes a particularly unique scheme which places an assessment of the defendant’s dangerousness at the center of the sentencing decision. Using data gathered from personally conducted interviews with forty-six former capital jurors and trial transcripts from each trial in which they served, this thesis demonstrates how the current sentencing scheme in Texas fails to provide jurors with an adequate vehicle for considering mitigation evidence. Beginning with an analysis of the process of jury selection this study examines the various ways in which the sentencing scheme is explained to potential jurors by the judge, prosecution, and defense attorneys. Of crucial importance is how the mitigation instruction is reconstituted by trial judges and prosecutors into an extension of the defendant’s potential future dangerousness. Emerging from this analysis is the central role that the interpretation of the sentencing statute by legal actors play in determining how jurors view the evidence presented throughout the trial, as well as what factors they believe they are legally permitted to consider in sentencing. The findings of this study strongly suggest that the focus of the sentencing scheme on the defendant’s dangerousness inhibits jurors’ ability to view mitigation evidence unrelated to the crime as mitigating. Thus, the Texas capital sentencing statute in its application appears to prevent jurors from giving effect to personal mitigation, an essential element of a constitutionally satisfactory death penalty statute.

Keywords: aggravating factors
mitigating factors
capital punishment
juror decision-making
sentencing
Advisor: Hoyle, C
The civic reformation in Coventry, 1530-1580

This thesis considers the civic elite in Coventry during the Reformation, from 1530-1580. It describes how the presence of a longstanding civic and political culture, dating back to the late middle ages, helped to mitigate religious change and bring other economic and social priorities to the fore during this period. The thesis looks at contemporary understanding of ideas of the city, including civic history and political power, as well as the economic forces which shaped the civic government?s interaction with other political hierarchies and the broader social world of the kingdom. It is argued that, although the corporation was keen to protect and define the political and physical boundaries of the city, they lived in an environment that was permeable to outside influence and the presence of geographically broad social and political networks. Urban political disputes are also examined, with the aim of elucidating those principles which ensured the smooth running of civic government and the control of the city by the corporation and the civic elite. Religious disagreements during the 1540s and 1550s are examined in detail, to show why, despite the potential for turmoil, the city never saw the breakdown of order or the political hierarchy. The spread of protestantism during later decades is dissected, alongside attempts to maintain urban religious provision at an acceptable standard, and to preserve the structures and hierarchies of civic religion. The thesis concludes that, even in cities like Coventry, where the effects of the dispute and dissonance that came with the growth of a new religion were strongest, it was possible for the traditional moral rules of urban governance to ensure that the city was an ordered and successful society well into the latter half of the sixteenth century.

Advisor: Gunn, S
The double CUE domain of chromatin remodelling factor SMARCAD1

ATP-dependent chromatin remodellers represent a class of proteins that restructure chromatin through the action of a conserved helicase-like ATPase domain. Remodellers typically have several accessory binding domains alongside the ATPase. These confer target specificity and most commonly recognise histone post-translational modifications.
SMARCAD1 is a ubiquitous chromatin remodeller involved with DNA replication and re- pair. It binds directly to PCNA at the site of DNA replication and recruits co-repressor KAP1 in order to silence newly produced chromatin. In contrast to most other chromatin remodellers, SMARCAD1 does not contain several different types of accessory domains. Only two CUE do- mains have been identified in addition to the SMARCAD1 core ATPase domain. CUE domains are a type of helical ubiquitin-binding domain.
This thesis presents the findings of an investigation into the structure and function of the SMARCAD1 double CUE domain. The solution NMR structure is presented with results from NMR binding experiments mapped onto the structure. Each CUE domain was found to be an independent helix bundle connected by a dynamic flexible linker. The N-terminal CUE domain, CUE-1, binds ubiquitin and has an adjacent SUMO (a ubiquitin-like protein) binding motif on a protruding extended helix. The C-terminal CUE domain, CUE-2, has a very similar structure to several published CUE domains but does not bind ubiquitin due to a charged substitution at a highly conserved CUE consensus position. The SMARCAD1 double CUE domain binds KAP1 from nuclear extract and is likely to mediate the interaction between SMARCAD1 and KAP1. SMARCAD1 double CUE domain is not involved with PCNA binding.

Keywords: CUE domain
ubiquitin
nuclear magnetic resonance
SMARCAD1
chromatin remodelling
protein structure
Advisor: Mancini, E
Redfield, C
Pulmonary vascular reactivity and fluid balance

This thesis is concerned with pulmonary vascular responses to hypoxia and with pulmonary fluid balance in the rabbit. The isolated perfused lung was used to investigate these issues; dextran and albumin (in varying concentrations) were added to the perfusate as colloids. Albumin was found to be more effective at delaying pulmonary oedema than dextran, probably due to its molecular shape and charge. Having established an effective preparation, the effects of hypoxia were studied.
Hypoxia elicited a rapid increase in pulmonary vascular resistance (PVR), followed by a decline to a plateau above the euoxic baseline over two hours. Multiple exposures to hypoxia resulted in an attenuation of the initial vasoconstriction with a potentiation of the slower vasoconstriction. Endothelin-1 (ET-1) is a potent vasoconstrictor, which has been suggested to play a role in hypoxic pulmonary vasoconstriction (HPV). Phosphoramidon (an inhibitor ET-1 production and degradation) enhanced both phases of HPV, indicating that ET-1 does not mediate HPV, although it plays a modulatory role.
The inhibition of nitric oxide synthase (NOS) by N°-nitro-L-arginine methyl ester (L-NAME) reduced both phases of HPV; this may have been due to L-NAME's antagonism of muscarinic receptors. L-NAME also caused an increase in the rate of weight gain of the isolated lung. This increase was attenuated by a mast cell stabilizer (lodoxamide) as well as by a cGMP analog (8Br-cGMP), indicating that nitric oxide may usually aid pulmonary fluid balance by stabilizing mast cells and by relaxing endothelial cells via cGMP.
The role of the ET B receptor in HPV was studied in isolated rabbit pulmonary arteries mounted on a tension myograph. Hypoxia elicited a small initial vasoconstriction followed by a large dilation, which slowly lessened over two hours. The initial vasoconstriction was found to be endothelium-dependent, while the subsequent vasodilation was endothelium-independent. Antagonism of the ET B receptor with BQ- 788 slightly potentiated the initial vasoconstriction to hypoxia, while the subsequent dilation remained unchanged. The ET B receptor was not found to have a great influence on HPV in this preparation.

Advisor: Dorrington, K
Popular Humour in Stalin's 1930s: A Study of Popular Opinion and Adaptation

This thesis contributes primarily to answering two broad questions within the current scholarship on ‘everyday life’ in the Soviet Union: (1) How did Soviet citizens perceive, understand, and adapt to the 1930s? And (2) What were the principal associational structures of Soviet society in these years? These issues are not easily separated, with the second constituting a vital element of the first. They are therefore explored simultaneously in the first three chapters, which examine, respectively, the nature and possibilities of joke-telling in the 1930s; the principal targets of that humour; and, thirdly, its implicit assumptions, values and thematic proclivities. The fourth chapter concentrates on the structure and nature of sociability in the 1930s, and the final chapter incorporates those conclusions in order to address the larger question of how Soviet citizens came to understand and adapt to life in these years – for they did so together, rather than alone as old totalitarian theories of ‘atomisation’ proposed.
The thesis makes two principal arguments. Firstly, all unofficial associational ties in this decade were necessarily underlaid by (and hence reliant upon) trust; therefore, the fundamental social unit in the 1930s was the trust group (small groups of citizens bound together by trust). Secondly, citizens adapted to the 1930s via an intricate blend of acceptance and criticism or, rather, of acceptance through the process of criticism. By criticising that which could not be changed, ‘ordinary’ Soviet citizens could retain some agency of their own and shared these interpretive acts with those whom they trusted. Rather than forming a critical ‘resistance’ or ‘dissent’, these processes created a pathway to adaptation without becoming simply crushed or brainwashed by ideology, and simultaneously shaped a complex, mutually affective interaction between popular values and official ideology.

Keywords: Soviet Union
Popular Opinion
Resistance
Trust
Stalinism
Popular Humour
Advisor: Priestland, D
Stargardt, N
Electrically detected magnetic resonance in semiconductor and carbon nanodevices

Electrically detected magnetic resonance (EDMR) is a sensitive spectroscopic technique, which can be used to readout few to single electron spins in semiconductor and carbon nanodevices for applications in solid state quantum information processing (QIP). Since only electrically active defects contribute to the EDMR signal, this technique can be used further to investigate defects and impurities in photovoltaic devices, in which they limit the sunlight-to-energy conversion efficiency significantly. Here, I employ X-band EDMR for semiconductor defect analysis and identify the most important recombination centres in Czochralski silicon with oxide precipitates, which can be intentionally grown to confine detrimental metallic impurities to inactive regions of the wafer in order to serve as a defect-free substrate for modern silicon photovoltaic devices. Those experiments show that oxide precipitation is accompanied by the formation of silicon dangling bonds. Furthermore, I describe a very promising route towards the fabrication and readout of few to single electron spins in carbon nanotube devices, which can be characterised structurally via transmission electron microscopy in order to relate their electrical and spin properties with their structure. Finally, I employ EDMR to read out electron spin states in donor-doped silicon field-effect transistors as a prerequisite for their application in QIP. I report on a novel cryogenic probe head for EDMR experiments in resonant microwave cavities operating at 0.35 T (9.7 GHz, X-band) and 3.34 T (94 GHz, W-band). This approach overcomes the inherent limitations of conventional X-band EDMR and permits the investigation of paramagnetic states with a higher spectroscopic resolution and signal intensity. Both advantages are demonstrated and discussed. I further report on a novel mechanism giving rise to the EDMR effect in donor-doped silicon field-effect transistors, which is capable of explaining why the EDMR signal intensities of the conduction electrons are enhanced by a factor of ∼100, while the donor resonance signals increase by a factor of ∼20 from X- to W-band only. The spin-relaxation and dephasing times are extracted from a series of pulsed-EDMR measurements and confirm this model. The author gratefully acknowledges funding from Trinity College Oxford, Department of Materials, EPSRC DTA, and Konrad-Adenauer-Stiftung e.V. (Begabtenförderung).

Keywords: solar cell
carbon nanotube
semiconductor
electrically detected magnetic resonance
Czochralski silicon
silicon
carbon
magnetic resonance
microwave cavity
quantum information
field-effect transistor
Advisor: Briggs, A
Ardavan, A
Morton, J
An analysis of interploidy crosses in maize

Reciprocal crosses between plants containing different genome numbers have been demonstrated to show alternate phenotypes in many species and are often lethal. The effects of interploidy crosses on kernel development in maize (Zea mays) have been reassessed using markers for two cell domains: the aleurone and the basal endosperm transfer layer (BETL); and by monitoring gene expression. The study confirms previous observations and offers novel insights into genomic interactions.
Endosperms from maternal excess crosses (tetraploid mother, diploid father) displayed reduced mitotic activity, and an accelerated rate of differentiation generally, including early starch accumulation, and earlier, atypical aleurone formation. The BETL failed to form normally, being replaced with aleuronelike cells, except for a few interspersed cells. Gene expression was altered, including those encoding cell domain markers and storage molecules.
Paternal excess endosperms (diploid mother, tetraploid father), showed an increase in cellular proliferation. Generally, differentiation was delayed: starch accumulation began late, and formation of the aleurone layer was delayed, and was morphologically highly irregular. BETL specification was also disturbed, with only a few cells showing characteristic wall modifications very late in development. Later development of the whole endosperm was characterized by ectopic gene expression, and zones of high cell proliferation. A greater proportion of the genome was mis-expressed in these crosses, reflecting the more extreme phenotype. Although expression levels of marker genes did not reflect the failure to develop a normal BETL, it may be that the cells in the BETL region had undergone an modified developmental program.
This work is considered in the context of evolutionary models which state that different parental roles lead to differential expression of genes from their respective genomes, and is compared with evidence from arabidopsis. The current study is considered generally supportive of such models.

Advisor: Dickinson, H