Coming dissertations at Uppsala university
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Exploring Uncertainty and Significance : Analysing Human Response to Environmental Risk with Computational Archaeology
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-526685
As humanity confronts the escalating challenges posed by rapid climate change, it becomes increasingly urgent to understand the complex dynamics of human-environment interactions to mitigate its multifaceted impacts. Archaeology, with its long-term perspective, offers the opportunity to examine past societal responses to environmental risks across diverse locations in Northwestern Europe and temporal scales.
This dissertation aims to contribute to this critical endeavour by exploring the socio-environmental dynamics and adaptive strategies of past societies, to inform effective responses to climate change challenges in both the present and future. Utilizing computational archaeology, which integrates digital technologies and computational methods to analyse big data, the dissertation employs probabilistic approaches, including Bayesian modelling like summed probability distributions of radiocarbon (14C) data, to confront uncertainties inherent in reconstructing past human-environmental dynamics from interdisciplinary datasets. Additionally, quantitative methods, such as correlation tests and null hypothesis testing of 14C data, are employed to identify significant shifts in these dynamics, translating insights into quantitative terms for enhanced integration with policy-making processes.
The primary objective of the dissertation is to illustrate how the integration of archaeological and environmental big data can enrich the understanding of human responses to environmental challenges. The papers in this thesis demonstrate how computational methods can be applied to big data to understand spatiotemporal changes in human-environmental variables, uncovering risk management strategies and societal vulnerabilities. The papers highlight cases where human communities experienced mitigated adverse effects from severe environmental shifts due to diverse socioeconomic strategies. Simultaneously, the results emphasize regional variations in the impacts of climate change, crucial for understanding the effectiveness of human responses. Moreover, the thesis exhibits how big data analytics both complement and challenge existing archaeological interpretations, contributing to the development of new theories. Importantly, it underscores the significance of diverse socioeconomic strategies in mitigating risks, especially in the face of abrupt environmental events.
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Studies of the Grid Connection of Offshore Renewable Energy Sources : Technologies and Simulations
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-526701
A substantial increase in renewable energy sources connected to the electrical grid is imperative to achieve net-zero emissions from the electricity sector. Marine energy sources, like marine current power and wave power, have the potential to significantly contribute to the increase of electricity from renewable energy sources. A crucial aspect of enabling marine energy utilization is the development of electrical systems for offshore renewable energy. Hence, this thesis addresses challenges regarding the grid connection of offshore renewable energy.
Two important questions for offshore renewable energy are how to construct the offshore electrical grid and how to transmit the power to the shore. This thesis provides a review of AC and DC collection grid topologies and compares HVAC and HVDC transmission for offshore applications. It is concluded that HVDC is the preferred technology for transmission distances exceeding 50 to 100 km.
Regardless of the configuration of the offshore collection grid, the energy converters must be connected to the collection and distribution grid. Uppsala University has deployed a marine current energy converter in the river Dalälven in Söderfors, Sweden. The grid connection system at the test site is based on a back-to-back converter technology. In the thesis, a simulation model of the grid connection system of the energy converter is presented. The simulation model is used to evaluate MPPT methods for marine current power. An advanced hydrodynamic model based on a two-dimensional free vortex method is utilized for this purpose. Additionally, a low-complexity hydrodynamic model is incorporated into the simulation model to assess electrical grids for marine current energy. One AC and one DC collection grid, each comprising five marine current energy converters, are compared. Furthermore, three DC collection grids, each with ten marine current energy converters, are assessed and compared.
The grid connection system at the Söderfors test site includes an LC filter connected to a power transformer. A novel transfer function is derived for this system, and the transfer function is verified with simulations and experimental investigations. It is shown that the derived transfer function accurately captures the frequency response of the experimental system.
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Antibiotic-Induced Damage on the Intestinal Microbiota and Treatment of Urinary Tract Infections Caused by ESBL- and Non-ESBL-Producing Bacteria
Link: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-526646
Therapeutic options for urinary tract infection (UTI) caused by Escherichia coli and Klebsiella pneumoniae are limited due to resistance against cephalosporins and carbapenems, which is typically mediated by the production of extended-spectrum β-lactamases (ESBLs) and carbapenemases. ESBL-producing bacteria are frequently co-resistant to other antibiotic classes, resulting in a shortage of treatment options. While all systemic antibiotic treatments are likely to disturb the microbiota and increase selection of resistance, evidence on the extent and persistence of such effects for different antibiotics is limited. The primary objective of this thesis was to investigate the therapeutic effect of carbapenem-sparing and narrow-spectrum oral antibiotics in the treatment of UTI, and to evaluate the impact of commonly used antibiotics on the intestinal microbiota.
The first study investigated the efficacy of nitrofurantoin and pivmecillinam for lower UTI in men (n=171), with trimethoprim as a comparator. We concluded that nitrofurantoin and pivmecillinam are suitable for empirical treatment of lower UTIs in men, considering their high activity against Eschericha coli and limited impact on the microbiota.
In a prospective multi-center study conducted at 15 infectious diseases hospital departments, patients (n=235) with UTI caused by ESBL-producing Enterobacterales were recruited. We aimed to evaluate clinical and microbiological treatment outcomes and relapse rates. The results indicate that carbapenem-sparing antibiotics were effective for UTI caused by ESBL-producing Enterobacterales and can be recommended for non-critically ill patients. Moreover, we noted that certain bacterial genetic features (e.g., ST131 in Eschericha coli and haemolysin) were associated with microbiological failure and relapse.
In a randomized, controlled trial with healthy adults (n=86), we investigated the impact on the microbiota of five antibiotics (ceftibuten, ciprofloxacin, nitrofurantoin, pivmecillinam, trimethoprim-sulfamethoxazole) that are commonly used for UTI. Fecal samples were collected before and up to one year after five days of antibiotic treatment. Ciprofloxacin demonstrated significant immediate and long-term disruption of the intestinal microbiota in terms of diversity and taxonomy and stands out in comparison with the other antibiotics included in the study.
In a prospective study, we investigated the intestinal microbiota in patients with hematological diseases undergoing hematopoietic stem cell transplantation (HSCT, n=88). Changes over time and during antibiotic treatment and potential associations between the intestinal microbiota at baseline and patient outcomes were explored. Oral ciprofloxacin demonstrated a significant impact on the intestinal microbiota, which was greater than the impact of intravenous broad-spectrum antibiotics. A low microbiome diversity at baseline was associated with neutropenic fever and antibiotic treatment following HSCT.