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Jet charge in pp and Pb-Pb collisions measured with the ALICE experiment at the LHC
Get PDFJet charge is the momentum-weighted sum of a jet’s electric charges. The value of a jet’s given jet charge is influenced by the parton that initiated the jet. This influence shifts the net charge towards the charge of that progenitor parton. This property offers a way to study the energy-loss from the QGP. Generating templates for the jet charge distribution for a given progenitor parton using Monte Carlo (MC) data and then fitting these templates to real data allows jet yields to be extracted. Two different techniques were investigated for identifying the progenitor parton of the jet. The first of the techniques employs the structure of the MC data and framework. The second of these techniques selects the parton based on the constituent of the jet with the largest momentum.
The yields of jets produced from distinct types of parton have been measured in pp and Pb-Pb data at √sN N = in order to investigate the effects of the QGP on quark and gluon jets. It has been suggested that gluons will interact more strongly with the QGP when compared to quarks. Thus, gluon jets are expected to be more heavily suppressed by the QGP. The background subtraction in the Pb-Pb data was conducted using the constituent subtraction method. Suppression of gluon jets is found at medium centrality collisions (i.e. in the centrality range 40-80%); however, in the most central collisions, it is likely that the background-dominated environment prevents the jet charge distribution templates from being accurately fitted to the experimental data. In order to conclusively demonstrate gluon suppression by the QGP using measurements of the jet charge observable, a better method of handling the effects of jet charge in the most central collisions must be developed. This thesis presents the first measurements of jet charge at ALICE using Run 2 data
Snow accumulation and melt responses to warming across the Northern Hemisphere
Get PDFSnow is an essential component of many Earth systems and its response to global warming is critical to understand. This thesis aims to advance our understanding of snow accumulation and melt responses to global warming. However, research into snow accumulation and melt is hindered by a lack of observations of snowpacks in space and time. This thesis provides a novel, open access dataset of continuous snow water equivalent (SWE) time series across the Northern Hemisphere (the NH-SWE dataset) based on observations of snow depth. This uses an established model to convert snow depth to SWE as well as a regionalisation of model parameters for application at the global scale. The model shows an excellent performance for key snow indicators such as peak SWE and the onset of snowmelt. The new hemispheric dataset is used for investigating long-term trends in snow accumulation and melt. Widespread declines in snow accumulation are shown across the Northern
Hemisphere except the coldest climates. The response of snowmelt rates to warming is more complex, and this work demonstrates a range of both faster and slower melt responses to warming that depends on the combined effects of changes in snow accumulation, amount of warming, and timing of the snow season. As a result, a diversity of snowmelt rate trends is observed across the Northern Hemisphere, highlighting snowmelt changes are complex to predict regionally, and requires understanding the nuances of the key drivers. Additionally, this thesis provides insights into temperature-index snowmelt modelling for applications at the global scale. We show the robustness of using simple snowfall and snowmelt temperature thresholds and estimated degree-day factors validated using the NH-SWE dataset. A simple temperature-index model using temperature and precipitation time series from climate networks shows a good performance in simulating snow water equivalent time series for most stations across the Northern Hemisphere
Rural wage Labour in Late Antique North Africa
Get PDFCasual rural wage labour in the Roman world is an underdeveloped topic, with the arguably first and last main work on the topic being published in 2013 using a methodology relying on comparison to modern times and without the aim to be a consistent model of how wage labour was procured and recruited in the countryside. In this thesis I have provided the first holistic model of rural unspecialised wage labour in the North African countryside between the 4th and 5th centuries, accounting for the characteristics of the workers that made up the labour pool, how they were organised when hired for labour-intensive tasks such as the harvest, and how disputes in affairs relating to the employment of casual wage labour were resolved. This model has been constructed primarily from primary sources, including literary texts, inscriptions, and material culture, both from North Africa and other areas of the Roman world, primarily Egypt.
The main finding of this thesis is that wage labour was primarily used for harvesting and was often hired through contractors who assembled gangs of workers. These contractors were part of the rural middle stratum that could afford to provide securities to landowners for the proper execution of the works but were also willing to devote their time and effort to coordinate harvest labour for profit. The workers they managed were in considerably lower socio-economic strata and very diverse in their profile. Although most of them would have been established locals coming from nearby, some minority presence of urban and transhumant populations could have been possible. The plurality of workers would have been young and male, but older and female workers also participated. Finally, disputes arising from the employment of labour would have likely gone through episcopal mediation, although the sectarian dispute between Catholics and Donatists might have threatened to disrupt this practice
An exploration of how self-regulation develops, is supported, and understood in the Reception classroom
Get PDFIn recent years, there has been an increased focus in education on self-regulation and self- regulated learning in young children, leading to it being included in the revised 2021 statutory guidance for the foundation stage (DfE, 2021b). The reasoning for this stems from research and educational theory dating back to the 1960s up to the present day, that links good self- regulation with better success in life and academic outcomes. Much of the literature and research has been undertaken within the areas of cognitive psychology, and social and developmental psychology. It has focused on working memory, inhibition and shifting, known as executive functions in cognitive psychology, and metacognition and reflectivity in social and developmental psychology, which are understood to be necessary components for self- regulation.
This study comprises of two case studies and seeks to explore and further understand how self-regulation develops in young children, how it is supported in a classroom context, and understood by teachers working with the revised 2021 curriculum. A blend of interviews, observations, and questionnaires have been used together data exploring stakeholders’ understanding of self-regulation within the context of a reception classroom. The fieldwork was undertaken in 2021, following two academic years of disruption and school closures due to the Covid-19 global pandemic. As such, the impact of this unprecedented disruption is also considered.
The findings suggest teachers are aware of the importance of emotional development for the acquisition of skills necessary for learning, but their understanding of the breadth of what self-regulation means has not been developed. Further support through training and continued professional development (CPD) will enable teachers to support children in targeted and meaningful ways. A school’s culture and the relationships between staff and parents also have an impact on the children’s experience while in the classroom. The pedagogy of early years teachers supports children to develop the necessary skills for self- regulation. However, this is not always recognised as distinctive and there is the possibility of missed opportunities for some children.
The study shows the breadth of other factors such as parents and home experiences that are critical to a child’s development of self-regulation before they enter school. These important aspects can be used to understand why some children are, more or less, affected with regards to their ability to self-regulate and the impact that can be attributed to the disruption and school closures caused by Covid-19. Findings suggest the need for a greater understanding of the importance of parenting and child development on a societal level.
Contributions identified can be used to inform future research and policy, utilising the pedagogical tools developed from this study into classroom practice to enhance support and provision for children in developing self-regulation skills
Towards enhancement of conflict management in construction contracts
Get PDFThis thesis is concerned with a long-standing problem that continues to undermine the performance of the construction industry in the UK and internationally; that is, inadequate conflict management in construction contracts. Because the adverse financial and societal consequences of that problem are substantial, they have been repeatedly reported at a national level. However, there is no clarity on the reasons behind the construction industry’s general failure to manage conflict satisfactorily. With a focus on construction contract practice, this research joins the dots between law, economic theory, and organisational studies, to tackle two main questions. The first is, what is the root cause of the conflict management deficit in the construction industry? The second is, what is the solution for fixing the root cause? Addressing these questions should be of interest to practitioners willing to deliver more successful construction projects, to researchers in the fields of long-term contracts and dispute resolution, and to governments seeking to reduce financial wastage from the national annual budget. The thesis argues that there is a major pitfall in using a construction contract as a mechanism of conflict management and, unless that pitfall is addressed in the contract design, poor conflict management will continue to be the norm in the construction industry. The thesis proposes a process that can be integrated into construction contracts for addressing the pitfall identified. This process, it is submitted, can be suitably standardised in construction contracts, which makes it well-placed to support the enhancement of conflict management in the construction sector, not only in the UK, but globally
A multimodal investigation into the relationship between ongoing brain state dynamics and visual response variability
Get PDFThe human visual system exhibits a large amount of variability in visual responses, even when presented with identical stimuli, yet the mechanisms behind this variability remain poorly understood. This thesis utilised simultaneous EEG-fMRI and Hidden Markov Modelling to investigate ongoing brain state dynamics and evaluate their impact on visual responses. The first results chapter (Chapter 3) investigates the ability of Hidden Markov modelling to identify differences in BOLD and alpha brain state dynamics between eyes open and eyes closed rest. The results showed that each rest condition shows significantly different BOLD and alpha brain state dynamics, with the open condition being associated with attention-based network states and a reduction in alpha power. Hidden Markov modelling was then applied to a visual dataset, in which participants viewed left visual field checkerboards passively (i.e. no task) and actively (i.e. identifying target stimuli). A total of three separate models were trained: a whole-brain BOLD state model (Chapter 4), an alpha state model (Chapter 5) and a thalamus BOLD state model (Chapter Chapter 6). The results of these models demonstrated that the HMM state active at baseline had a significant impact on the subsequently evoked BOLD, VEP and alpha event-related de/synchronisation responses. Thus, the ongoing brain state dynamics, defined by BOLD measures and electrophysiological, explain a significant proportion of the variability in visual responses, highlighting the importance of the baseline. Overall, this thesis demonstrates that ongoing brain state dynamics interact with visual responses, resulting in the observed variability, highlighting the importance of accounting for the baseline in visual research and neuroimaging
The Kura-Araxes culture in Azerbaijan and its wider regional context in the Caucasus
No full textThe Kura-Araxes Culture (hereafter KAC) is one of the most distinctive and long-lived archaeological complexes of the ancient Near East, which existed roughly between 3500-2500 BC, covering an astonishingly wide geographical areas during the Early Bronze Age (hereafter EBA). Despite increasing investigations and studies of the KAC communities in the Caucasus region, our knowledge of Azerbaijan is still fragmentary. The primary objective of this study was to focus, for the first time, on the comprehensive study of the case study area, Azerbaijan, in order to develop a deep understanding of the life of KAC communities during the EBA. The second objective was to evaluate Azerbaijan’s place in the broader picture of the KAC and to develop a wider interpretation of the culture that will be interrogated and reconsidered broadly in the Caucasus and in the wider extent of the ‘KAC world’ for future research. To meet these objectives, a comprehensive Gazetteer was created to provide a detailed account of every known KAC site in the contemporary borders of Azerbaijan. This will enable scholars to engage with material previously inaccessible. More importantly, this comprehensive study of the KAC in English will be widely available as an international resource for the scholars of Azerbaijan and beyond.
The understanding of the life of KAC communities in the region is mainly restricted to ceramic assemblages. This study addresses this gap and is the first to examine existing fragmented records surrounding the settlement pattern and the nature of settlement structures, funerary practices, and building tradition in Azerbaijan. This work interrogates the notion of KAC within this wider dataset contrary to general statements asserted by earlier scholars. This data approach was used to understand the narrative method of the chronological development of the culture, through the implication of homogeneity-heterogeneity features, traditional peculiarities of local variants, and the values and worldviews of these communities.
This study contributes to the understanding of a broader picture of the culture and presents a more representative narrative of KAC communities in Azerbaijan. The research found that KAC in Azerbaijan had a sense of unity, as demonstrated by some shared collection of artefacts and features, to the rest of the KAC regions in the Caucasus. Interestingly, it was also found that alongside a similar set of commonalities, there are some distinctive traits that are unique to these communities living in the region
Investigating the role of complement in the pathogenesis of pre-eclampsia in previously healthy pregnant women, and in high-risk groups.
Get PDFPre-eclampsia (PE) is a leading cause of obstetric morbidity and mortality. Certain groups of women, including those with chronic kidney disease (CKD) and those of sub-Saharan African (SSA) ethnicity, are at particularly high risk. There remains no definitive treatment other than expedited delivery of baby and placenta. Previous studies suggest a role for complement dysregulation in the pathogenesis of PE, but results are often conflicting, and it remains unclear whether changes in circulating complement concentrations reflect a general heightened inflammatory state in PE or are directly associated with placental complement-mediated injury.
This thesis tested the hypothesis that PE is associated with excessive complement activation within placental tissue, with concurrent complement activation within the maternal and fetal circulation, and that groups with a high prevalence of PE, and of PE with severe features (women with CKD and women of SSA ethnicity) would exhibit a greater degree of systemic complement activation. Three arms of research were conducted, and I report:
• In a cohort of previously healthy women, PE was associated with significant placental complement deposition, associated with concurrent changes in maternal and fetal circulating complement markers (reduced maternal properdin and C4, and elevated maternal and fetal Ba). Placental C4d deposition was strongly correlated with maternal properdin and C4, suggesting that those patients with the most excessive changes in circulating markers of complement activation also have the greatest extent of placental complement-mediated damage.
• There was no evidence of excessive complement activation in the maternal circulation in superimposed PE in a cohort of women with CKD. However, raised Ba levels were associated with adverse pregnancy outcomes in women with CKD.
• There was no evidence of excessive complement activation in PE in a Ghanaian cohort of women of SSA ethnicity when compared to healthy pregnant controls. However, pregnant women of SSA ethnicity did have significantly elevated levels of C5b-9, serum free light chains, and immunoglobulin G, when compared to the UK-recruited cohorts; suggestive of a baseline elevated inflammatory state.
The results suggest that inhibition of complement activation is a potential therapeutic target for certain groups of women with PE. However, PE is a heterogenous syndrome and additional pathophysiological mechanisms may contribute to the development of disease in women with CKD and women of SSA ethnicity
Perceptions of advice-giving on Reddit: a pragmatic investigation of moves and upvotes
No full textTurning to the internet to seek, receive, and give advice has become increasingly widespread. One of the most popular online sites where advice interactions routinely occur is Reddit (www.reddit.com). As a predominately public platform, the userbase of Reddit presumably extends beyond only registered contributors. Consequently, it is important to understand advice interactions on Reddit not only from a descriptive perspective (i.e. analyzing how advice-seekers and advice-givers interact on the site), but also how other audiences might perceive or interact with the advice using the platform’s mediated features (e.g. Reddit’s upvote system). Thus, this project investigates Reddit advice-giving formulations in addition to their relationship with Reddit’s upvote system, and how we might perceive and evaluate the quality of advice.
My exploration of advice-giving on Reddit consists of three phases. In phase one, I adopt move analysis (c.f. Swales, 1981, 1990) to explore the types of moves used in Reddit advice-giving. I also extend the theoretical conception of the move into pragmatic perspectives (specifically, the pragmatic model of Spencer-Oatey & Kádár, 2021). In phase two, I explore the association between moves and upvotes using Poisson regression modeling. Finally, phase three of my project involves designing and administering an experiment informed by the findings of my move analysis in order to tease out these results in a more fine-grained manner. Moreover, as the study of advice is not solely situated within linguistics, I also incorporate theories and frameworks from communication studies and psychology to generate an interdisciplinary-informed understanding of advice.
The methodological choices made throughout this project culminates in a research approach that expands the analytical and theoretical boundaries of move analysis as well as our knowledge of advice-giving. At the same time, my methodology brings pragmatic conceptions of the upvote system to the fore, providing insights into what the upvote system means when it is used (or not used) to interact with advice.
My results provide a granular and empirical understanding of both the association between upvotes and moves, along with how different advice-giving moves affect our perceptions of advice. I also advance our understanding of Reddit as a site for computer-mediated communication and our understanding of advice as an interactional process. Therefore, the findings of this project not only concern Reddit, but also have implications for our wider understanding of advice-giving
Interplay between innate epithelial sensing and mucosal immunity
Get PDFMaintenance of intestinal integrity is dependent on crosstalk between epithelial, stromal and immune cells and the gut microbiota. Nod-like receptor (NLR) apoptosis inhibitory proteins (Naips) activate the NLRC4 inflammasome upon recognition of gram-negative bacteria, leading to pyroptosis/apoptosis, intestinal epithelial cell expulsion and release of IL-1β, IL-18 and prostaglandin E2 (PGE2). NAIPs also appear to have homeostatic roles within the intestinal epithelium, as our group has previously shown that Naips suppress colonic tumourigenesis but enhancecolonic inflammation. We aimed to further understand the role of Naips on the immune compartment in inflammatory disease, usingmodels of colorectal cancer and Salmonella infection. Following Salmonella infection, ice lacking epithelial Naips (NaipΔ/Δ) had increased numbers of TCRαβCD8αα and TCRγδ+ intraepithelial lymphocytes, which was not caused by increased bacterial burden. Using colonic organoids, we identified increased IL-15/IL-15R in NaipΔ/Δ and altered basal levels of eicosanoids (PGF2α and 17,18-DiHETE) with altered expression of eicosanoid-related genes. However, organoid co-cultures suggested neither explained the increase in intraepithelial lymphocytes, with further work needed to elucidate the mechanism behind this. Following colorectal cancer induction, only slight differences were seen in the tumour infiltrating lymphocytes of NaipΔ/Δ mice compared to Naipfl/fl, though there was a trend towards decreased conventional CD4+ T cells and an increase in TCRγδ cells. However, NaipΔ/Δ cancer-derived organoids increased MHCII expression in response to IFNγ, whereas Naipfl/fl did not. This was not explained by differences in IFNγ signalling or prostaglandin production. Further investigation is needed to determine the exact role of Naips in colorectal cancer and why NaipΔ/Δ mice experience increased tumorigenesis
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