VictorJuiz/thesis huggingface dataset:
Inverting the signature of a path
Keywords: inversion
path
signature

This thesis consists of two parts. The first part (Chapters 2-4) focuses on the problem of inverting the signature of a path of bounded variation, and we present three results here. First, we give an explicit inversion formula for any axis path in terms of its signature. Second, we show that for relatively smooth paths, the derivative at the end point can be approximated arbitrarily closely by its signature sequence, and we provide explicit error estimates. As an application, we give an effective inversion procedure for piecewise linear paths. Finally, we prove a uniform estimate for the signatures of paths of bounded variations, and obtain a reconstruction theorem via that uniform estimate. Although this general reconstruction theorem is not computationally efficient, the techniques involved in deriving the uniform estimate are useful in other situations, and we also give an application in the case of expected signatures for Brownian motion.
The second part (Chapter 5) deals with rough paths. After introducing proper backgrounds, we extend the uniform estimate above to the context of rough paths, and show how it can lead to simple proofs of distance bounds for Gaussian iterated integrals.
The major histocompatibility complex, mate choice and pathogen resistance in the European badger Meles meles
Keywords: Meles meles
Major histocompatibility complex
pathogen resistance
European badger
mate choice

Studies of the evolution of the major histocompatibility complex (MHC) have been central to the understanding sexual selection and pathogen-mediated selection. The European badger Meles meles is well suited for exploring such questions because of its life history characteristics, reproductive biology and mating system. In this thesis, I examined both MHC class I and class II genes. Seven putatively functional sequences were found for class I genes and four for class II DRB genes. Evidence of past balancing selection of both genes was demonstrated by the dNdS ratio, by positive selection at the antigen-binding site (ABS) and by trans-species polymorphism of alleles within other mustelids and carnivores. MHC class I genes also showed evidence of concerted evolution, but domains showed different evolutionary histories. MHC genes may influence microbiota and odour of an individual and influence mating preferences. I examined the bacterial community of the subcaudal gland secretion and demonstrated a high number of bacterial species (56 operational taxonomic units), which cubs exhibited a higher diversity than adults. The microbiota may lead to an individual-specific odour as a cue signaling the MHC genotype of potential mating partners. I report the first evidence for a MHC- based mating preference in carnivores. Female badgers showed a MHC-assortative mate choice towards breeding with males that had functionally similar MHC genes, for MHC class II DRB genes. This applied to neighbouring-group matings. I also found considerable annual fluctuation in the occurrence of MHC-based mate choice. Based on genome-wide background in the same mating randomizations I found no evidence of inbreeding, which indicated that MHC similarity was apparently the actual target of mate choice. In line with MHC-assortative mate choice, MHC heterozygosity had no influence on the co-infection status. Individual MHC alleles did, however, associate with resistance and susceptibility to specific pathogens, suggesting that MHC diversity may be driven and maintained by pathogen-mediated selection through rare-allele advantages and/or fluctuating selection. My study of genetic characteristics, mate choice and pathogen pressures in a wild population revealed past and contemporary evolutionary process of the MHC genes. This increases knowledge of how the MHC may affect mating behaviour and sexual selection, ultimately influencing population processes.
In search of solidarity
Keywords: apartheid
international solidarity
transnational social movements

This thesis provides an account of the work of Canadian organizations that took part in the global anti-apartheid movement and then continued political advocacy work in South Africa post-1994. My central research question is: What explains the rise and fall of international solidarity movements? I answer this question by exploring the factors that allowed the Canadian anti-apartheid network to grow into an international solidarity movement and explaining how a change in these factors sent the network into a period of decline post-1994. I use two organizations, the United Church of Canada and CUSO, as case studies for my analysis.
I argue that four factors were behind the growth of the Canadian solidarity network: the presence of large CSOs in Canada willing to become involved in solidarity work, the presence of radical spaces in these organizations from which activists could advocate for and carry out solidarity work, the frame resonance of the apartheid issue in Canada and the political incentives the apartheid state provided for South African activists to encourage Northern support. Post-1994 all of these factors shifted in ways that restricted the continuation of international solidarity work with South Africa. Accordingly I argue that the decline of the Canadian network was driven in part by specific South African factors, but was also connected to a more general stifling of the activist work of progressive Canadian CSOs over the 1990s. This reduction of capacity was driven by the ascent of neo-liberal policy in Canada and worldwide. Using examples from a wide swath of cases I outline this process and explain how all four factors drove the growth and decline of Canadian solidarity work towards South Africa.
Extraction of clinical information from the non-invasive fetal electrocardiogram
Keywords: non-invasive foetal ecg
machine learning
signal processing

Estimation of the fetal heart rate (FHR) has gained interest in the last century; low heart rate variability has been studied to identify intrauterine growth restricted fetuses (prepartum), and abnormal FHR patterns have been associated with fetal distress during delivery (intrapartum). Several monitoring techniques have been proposed for FHR estimation, including auscultation and Doppler ultrasound.
This thesis focuses on the extraction of the non-invasive fetal electrocardiogram (NI-FECG) recorded from a limited set of abdominal sensors. The main challenge with NI-FECG extraction techniques is the low signal-to-noise ratio of the FECG signal on the abdominal mixture signal which consists of a dominant maternal ECG component, FECG and noise. However the NI-FECG offers many advantages over the alternative fetal monitoring techniques, the most important one being the opportunity to enable morphological analysis of the FECG which is vital for determining whether an observed FHR event is normal or pathological.
In order to advance the field of NI-FECG signal processing, the development of standardised public databases and benchmarking of a number of published and novel algorithms was necessary. Databases were created depending on the application: FHR estimation with or without maternal chest lead reference or directed toward FECG morphology analysis. Moreover, a FECG simulator was developed in order to account for pathological cases or rare events which are often under-represented (or completely missing) in the existing databases. This simulator also serves as a tool for studying NI-FECG signal processing algorithms aimed at morphological analysis (which require underlying ground truth annotations).
An accurate technique for the automatic estimation of the signal quality level was also developed, optimised and thoroughly tested on pathological cases. Such a technique is mandatory for any clinical applications of FECG analysis as an external confidence index of both the input signals and the analysis outputs.
Finally, a Bayesian filtering approach was implemented in order to address the NI-FECG morphology analysis problem. It was shown, for the first time, that the NI-FECG can allow accurate estimation of the fetal QT interval, which opens the way for new clinical studies on the development of the fetus during the pregnancy.
Functional and anatomical networks of executive control
Keywords: transcranial magnetic stimulation
diffusion weighted MRI
task switching
executive control

Actions are selected in the context of environmental demands and internal goals. Both change constantly and dynamically and several studies have addressed the issue of how information about these is represented, updated and integrated in the brain to form appropriate decisions and actions. The reprogramming of actions requires inhibition of movements or movement plans, resolution of response conflict and initiation of alternative actions. The right inferior frontal cortex (rIFC) and the presupplementary motor areas (pre-SMA) have been suggested to play a major role in response inhibition and action reprogramming. The degree to which inhibition of actions at a behavioural level can be related to physiological inhibition is unknown.
Using single and paired-pulse transcranial magnetic stimulation (TMS), we investigated M1 excitability and M1 internal inhibitory mechanisms during action reprogramming (see Chapter 2.1.1). The temporal pattern of M1 excitability and M1 internal inhibitory mechanisms differed from those during normal action execution and could therefore play a causal role in action reprogramming. These findings are important as M1 is likely to be the site of convergence from different influences exerted by regions in the frontal lobes.
In a second experiment we used paired-pulse TMS over rIFC and M1 to investigate functional rIFC-M1 interactions (see 2.1.2). We found that rIFC inhibited M1 excitability 175 ms after cue onset only in trials when actions needed to be reprogrammed and responses had to be inhibited, but not during normal action selection.
In a third experiment we used a combined paired-pulse TMS – diffusion tensor imaging (DTI) approach to elucidate anatomical pathways of functional pre-SMA-M1 and rIFC-M1 connectivity (see 2.2). We found extended networks of executive control and action reprogramming. These results suggest that both, pre-SMA and rIFC influence motor output via premotor areas and fronto-basal ganglia loops. Different latency periods of rIFC-M1 and pre-SMA-M1 interactions were mediated by different white matter paths and networks.
In a fourth experiment we tried to delineate the roles of rIFC and pre-SMA during action reprogramming using a combined paired-pulse TMS– repetitive TMS paradigm (see 2.3). The inhibitory influence exerted by rIFC over M1 during action reprogramming disappeared after mild and transient disruption of pre-SMA activity.
Besides elucidating a network of brain areas associated with action reprogramming and movement inhibition these experiments have interesting methodological implications.
Relative distance: practices of relatedness among transnational Kenyan families
Keywords: United Kingdom
kinship
transnationalism
Kenya
migration

In this thesis I examine familial dynamics and relations between Kenyan migrants in London and their non-migrant kin remaining in Kenya. Two transnational family configurations predominate: younger migrants and their non-migrant parents and siblings, and older transnational couples (migrant wives and non-migrant husbands). If migration is understood as a morally-laden social process, then how migrant and non-migrant kin engage with the distance(s) between them become the grounds on which what it means to be related is expressed and negotiated. Distance emerges not only as geographic and physical, but also as socially generated by the actions and inactions of kin. I argue that the emplacement of kin in different contexts post-migration, particularly younger migrants within a nascent Pentecostal community in London, mediates transnational kin relations. The thesis challenges a predominant strand of research on transnational families, which contends that migration disrupts kin relations and contributes to the commodification of love and care. Moreover, the focus on transnational Kenyan families fills a gap in African diaspora research that has largely focused on migrants from West Africa and issues of identity, diaspora politics, and development, while also addressing themes in African anthropology, such as, intergenerational reciprocity, social reproduction, and change.
Role of family in HIV prevention: systematic reviews and qualitative investigation of young Thai women in Bangkok
Keywords: systematic review
Thailand
Sexual health
focus group
intervention
HIV

Young women are particularly vulnerable to HIV. Despite the successful HIV prevention efforts in Thailand in the past, young Thai women are at increased HIV risk and in urgent need of effective HIV interventions. Numerous studies have emphasised the importance of family in determining young people’s sexual behaviour. This thesis explores the roles of family in shaping young people’s sexual decisions and examines the potential of family-involved HIV interventions (FIHIs) for young Thai women.
The thesis systematically examines studies across settings to determine whether involving family in HIV interventions could influence young people’s sexual behaviour. The findings suggest that FIHIs have a potential in shaping young people’s condom use practices. It identifies several key characteristics of effective FIHIs that can potentially be valuable for future HIV development in other contexts. Qualitative data collected from focus groups of young Thai women in Bangkok are analysed using the framework developed from the systematic review of qualitative studies. The findings highlight several challenges for future FIHIs for young Thai women. These are barriers to parent-child communication, a tension of coexistence of two divergent sexual norms - traditional/Thai versus modern/globalised, alternative sources of sexual health and HIV knowledge, the importance of family relationships, and the different circumstances and needs of young Thai women from different backgrounds. Future FIHIs for young Thai women should consider a comprehensive, structural and eco-developmental approach, simultaneously targeting both individuals and the wider environment. This thesis offers a new contribution to the HIV prevention and sexual health education literature and identifies the potential effectiveness of FIHIs tailored to young Thai women,constituting an important step in addressing the public health problems of HIV/AIDS infections in Thailand.
A demographic perspective on trait heritability and sex differences in life history
Keywords: mortality
population models
heritability
sex differences
integral projection models
population ecology
biodemography

Biologists have long used demographic approaches to answer questions in ecology and evolution. The utility of these approaches has meant a constant development and refinement of methods. A key milestone has been the development of phenotype structured population models that link ecology and evolution. Moreover, biostatistical research steadily improves methods to coax demographic information from scarce data. In this thesis, I build upon some of the recent advances in the field. My first three studies focus on the consequences of sex differences in life history for population dynamics. Firstly, I test whether males matter for the dynamics of African lion (Panthera leo) populations via a previously unquantified mechanism: the inheritance of phenotype from father to offspring. Secondly, I develop a method to estimate age-specific mortality rates for both sexes in species where one of the sexes disperses around the age of maturity. Thirdly, I apply this method to study variation in mortality between the sexes and between two populations of African lions. After these three chapters, which make contributions to the field of sex-structured population dynamics, I focus on the integration of phenotype structured modelling and quantitative genetics. I illustrate how heritability of a quantitative character that develops with age depends on (i) viability selection, (ii) fertility selection, (iii) the development of the phenotype with age, and (iv) phenotype inheritance from parents to offspring. Our results question the adequacy of quantitative genetics methods to obtain unbiased estimates of heritability for wild populations. This thesis advances our understanding of population development over ecological time scales. This knowledge has applications in conservation and population management, but also contributes to untangling evolutionary processes in wild animals.
Occupational pensions in Germany: an economic geography
Keywords: mixed models
pension savings
occupational pensions
individualisation
economic geography
defined contribution
local relationships
Riester reform
defined benefit
behaviour
social pacts

By the end of the twentieth century, the generous German public pay-as-you-go pension system had been struggling with a serious deficit due to the country’s ageing population. In 2001, the German government enacted the “Riester” pension reform, named after Mr. Walter Riester, the Labour Minister brokering it, which reduced the level of publicly provided pensions, and strengthened the funded occupational and private pillars in order to replace the loss in retirement income.
This thesis investigates the role and structure of occupational pensions during the Riester-reform and in its aftermath, using an economic geography perspective. In doing so, it discusses the role of trade unions and employer associations (social partners) in moulding the structure of the occupational system, and investigates the geography of occupational pensions both at employer and at employee level. Empirically, the thesis is based on an in-depth interview with Mr. Walter Riester, and a unique, proprietary data-set of a German occupational pension provider, containing information on 332 thousand employees and over 12 thousand employers.
The results show that the internal division of social partners played a critical role in leaving occupational pensions voluntary, but they have been successful in setting standards on the occupational pension market by means of collective bargaining. Employers and employees show systematic spatiotemporal patterns in their pension-related decisions, confirming the importance of local relationships and local contexts in implementing social partners’ measures and in the transformation of the welfare state. It is finally pointed out that the Riester-reform was a part of a gradual transition, which has been reducing employers’ autonomy in order to reinforce the social role of occupational pensions. To achieve that and to catalyse the reform process, employers’ and employees’ risk exposure has been mitigated in the hope that old-age poverty can be avoided.
First investigation on a two-stage CERN PSB collimation system
Keywords: collimation
particle physics
particle accelerators
physics

This thesis investigates the feasibility of a two-stage collimator for the PSB (Proton Synchrotron Booster) at CERN. Simulations of several shapes, sizes and materials were run and the indications from this study are that due to heating concerns either diamond is required for the first stage or a fast kicker would need to be installed to prevent damage in the event of beam loss. Aluminium is also possible with some compromise on performance. The final design would be subject to further simulations on nuclear scattering effects and requires the exact tune to be known; a parameter not yet decided.
The Khecarīvidyā of Ādinātha: a critical edition and annotated translation
Keywords: ethnography
Sanskrit
philology
Hinduism
yoga
tantra

This thesis contains a critical edition and annotated translation of the Khecarīvidyā of Ādinātha, an early haṭhayogic text which describes the physical practice of khecarīmudrā. 31 witnesses have been collated to establish the critical edition. The notes to the translation adduce parallels in other works and draw on Ballāla's Bṛhatkhecarīprakāśa commentary and ethnographic data to explain the text.
The first introductory chapter examines the relationships between the different sources used to establish the critical edition. An analysis of the development of the text concludes that its compiler(s) took a chapter describing the vidyā (mantra) of the deity Khecarī from a larger text to form the framework for the verses describing the physical practice. At this stage the text preserved the Kaula orientation of the original work and included verses in praise of madirā, alcohol. By the time that the text achieved its greatest fame as an authority on the haṭhayogic practice of khecarīmudrā most of its Kaula features had been expunged so as not to offend orthodox practitioners of haṭhayoga and a short fourth chapter on magical herbs had been added.
The second introductory chapter concerns the physical practice. It starts by examining textual evidence in the Pali canon and Sanskrit works for practices similar to the haṭhayogic khecarīmudrā before the time of composition of the Khecarīvidyā and then discusses the non-physical khecarīmudrās described in tantric works. There follows a discussion of how these different features combined in the khecarīmudrā of the Khecarīvidyā. Then a survey of descriptions of khecarīmudrā in other haṭhayogic works shows how the haṭhayogic corpus encompasses various differnt approaches to yogic practice. After an examination of the practice of khecarīmudrā in India today the chapter concludes by showing the haṭhayogic khecarīmudrā has generally been the preserve of unorthodox ascetics.
In the third introductory chapter are described the 27 manuscripts used to establish the critical edition, the citations and borrowings of the text in other works, and the ethnographic sources.
The appendices include a full collation of all the witnesses of the Khecarīvidyā, critical editions of chapters from the Matsyendrasaṃhitā and Haṭharatnāvalī helpful in understanding the Khecarīvidyā, and a list of all the works cited in the Bṛhatkhecarīprakāśa.