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Since the industrial revolution, humans have caused profound climate changes, primarily by releasing geological carbon into the atmosphere and increasing atmospheric CO2, with current levels reaching >400ppm, a concentration unprecedented in the last 800ka. This has led to far-reaching socioeconomic consequences for human society and risks for all levels of ecosystem. A better understanding of rapid climatic changes is desperately needed in order to inform mitigation and adaptation strategies for future climate change. The last glacial cycle experienced orbital and millennial scale climatic variability, as indicated by high latitude ice core records and many other high-resolution marine and terrestrial records. These climatic changes included, but were not limited to, changes in atmospheric CO2, temperature, the hydroclimate, sea surface temperature (SST), ocean circulation and ocean biogeochemistry. The ocean is thought to have played a key role in controlling and modulating these changes through its impacts on both heat transport and the carbon cycle. High resolution marine sediment cores can be used to reconstruct these changes and may help to elucidate the mechanisms behind them. To date, most studies have focused on the deglaciation, and only sparse, low-resolution records exist for Marine Isotope Stage (MIS) 4, a key paleoclimatic interval for the last glacial inception. MIS 4 is characterised by a rapid CO2 drop of ~40ppm, which is comparable in duration and magnitude to the first rapid increase seen during the last deglaciation. It also involved a large drop in temperature, as indicated by Greenland and Antarctic ice cores, a decrease in sea level, and a possible slowdown of Atlantic Meridional Overturning Circulation (AMOC) as reconstructed from various proxy records. Several millennial events occurred during MIS 4, including Heinrich Stadial 6 and Dansgaard-Oeschger (DO) events 16-19. MIS 4 is thus an ideal interval to study and disentangle, glacial-interglacial and millennial variability. It also provides a window into the mechanisms of rapid CO2 change and their contribution to longer-term (orbital) climate change. Furthermore, the termination of MIS 4 allows for a comparison with the last deglaciation. In this thesis, I collect paleoceanographic data to improve coverage of this important interval from a suite of sediment cores retrieved from the Iberian Margin in the Northeast Atlantic, and a single core from the deep Sub-Antarctic Atlantic core site. This thesis ultimately aims to enhance the current understanding of the ocean’s role in and response to abrupt and orbital-scale climate changes during MIS 4 and to draw lessons on its wider implications for climate variability. Ultimately, this may contribute to our understanding of natural carbon cycle-climate feedbacks that will play a role in anthropogenic climate changes in the future. High resolution planktonic foraminifera Mg/Ca-based SST reconstructions from the Iberian Margin during MIS 4 show that certain aspects of the surface ocean response may not always track Greenland temperature and that Greenland ice core records do not serve as a universal template for climatic variability across the whole of the North Atlantic, likely due to the seasonal habitat biases associated with SST reconstructions. A strong hydroclimate signal is shown in planktic foraminifera δ18O from the Iberian Margin, whereby glacial (MIS 4) hydroclimate variability is coupled to a combination of the high-latitude North Atlantic changes and low-latitude tropical hydroclimate. Furthermore, for the first time, a high-resolution Mg/Ca-based SST record from the Iberian Margin, covering the last 85ka, demonstrates clear similarities between MIS 4 and MIS 2. This includes a similar decoupling of sub-tropical summer SST from Greenland temperatures recorded in ice core records during pre-HS 6 MIS 4 and the Last Glacial Maximum (LGM). The record also emphasises that the most severe (coldest and driest) conditions occurred in the midlatitude North Atlantic during Heinrich Stadials, rather than the ‘peak’ glacial conditions of MIS 4 or the LGM. The deep ocean likely played a key role in modulating CO2 on millennial and astronomical timescales, for example through changes in its respired carbon inventory. Conservative parameters that are indicative of deep-water hydrography, and by extension circulation, are deep water temperature (Tdw) and associated δ18Odw. Reconstructed Tdw changes from the Iberian Margin show a larger influence of southern sourced waters during MIS 4 and particularly during HS 6. Atlantic sector Southern Ocean (SO) Tdw closely follows Antarctic temperature, atmospheric CO2 and the mean ocean temperature, implying that the deep SO contributed significantly to the global ocean energy budget on multi-millennial time scales across MIS 4, likely mediated by buoyancy forcing in the SO. This in turn was likely linked to sea-ice expansion at the MIS 5a/4 transition, aided by a parallel shoaling of North Atlantic Deep Water (NADW) as suggested by the North Atlantic Tdw record. Together with (arguably smaller) contributions from reduced air-sea gas exchange efficiency in the SO, these changes would have lowered atmospheric CO2 during MIS 4, through their impact on the solubility- and soft tissue “pumps” (i.e. the ocean’s disequilibrium and respired carbon budgets). Because the amount of respired carbon in deep-water broadly scales with the dissolved oxygen concentration, bottom water O2 reconstructions, [O2]bw, were investigated for a depth transect from the Iberian Margin and for the Atlantic sector of the Southern Ocean. Qualitative benthic foraminiferal assemblage records from a depth transect on the Iberian Margin show that shifts in oxygenated environments are primarily controlled by the quality and/or quantity of Corg reaching the sea floor, rather than [O2]bw. There are distinct shifts in assemblages associated with more periodic and/or degraded Corg flux during MIS 4 and an indication of low [O2]bw during HS 6 at the mid-depths, however no significant changes in the flux of Corg (i.e. ‘export production’) were found. Multi-proxy foraminiferal geochemical [O2]bw reconstructions from the Iberian Margin show a gradual decrease in [O2]bw at the mid-depth North Atlantic during MIS 4 with a minimum during HS 6, likely controlled by ventilation changes (i.e. changes in ocean circulation, including water mass sourcing combined with active but diminished transport, or altered preformed ‘end-member’ values). In the meantime, the [O2]bw record from the South Atlantic closely follows atmospheric CO2, likely indicative of ocean ‘ventilation’ impacts on ocean-atmosphere carbon exchange. Indeed, the Southern Ocean appears to have represented a significant reservoir for sequestering CO2 away from the atmosphere during MIS 4, as indicated by the respired- and equilibrium carbon inventory changes that are implied by the [O2]bw and Tdw reconstructions.

Abstract The effect of high temperatures as a degrading factor of rock materials is investigated in this study. Valdieri Marble samples, collected in a quarry in North-western Italian Alps, were subjected to thermal cycles (ranging from 105° to 600 °C) and to subsequent non-destructive and destructive laboratory tests with the aim of evaluating the variation of physical and mechanical properties as a function of temperature variations. Physical and mechanical measurements were complemented with microscopic observations on thin sections. The increase of crack density with temperature and the consequent porosity increases were found to be the main causes of degradation of physical and mechanical properties. In general, density, ultrasonic pulse velocity, wet electrical resistivity, uniaxial compressive strength and Young's moduli decrease as temperature increases. By contrast, peak strain and porosity increase. Correlations between temperature and physical-mechanical properties were proposed and compared to other relationships already established in scientific literature. A damage parameter to quantify the degradation of mechanical properties with temperature is also proposed.

Halide perovskites are the leading candidates for next-generation, low-cost optoelectronics with power conversion efficiencies well above 25%. However, operational stability remains a key challenge. Although there is an understanding that the microscale and nanoscale play a consequential role in determining the macroscopic performance and stability, significant gaps remain in the mechanistic understanding of degradation processes at the nanoscale and the mechanisms for stability in cation-alloyed systems. Nanoscale hexagonal phase impurities have been identified as problematic for operational stability, leading to both performance losses and morphological degradation. However, it is still unclear at what stage these phase impurities originate. Understanding this better is critical in order to mitigate the harmful effects of these phase impurities on performance and operational stability. Cation alloying is a commonly used technique in the field to mitigate these hexagonal phase impurities, although not without its challenges. In this thesis study, the nanoscale structural landscape of key halide perovskite compositions is studied. By taking snapshots of the perovskite at different states of the annealing process, the impact of phase impurities on device performance is characterised. Thereon, the mechanism by which composition dictates photostability in FA-rich perovskite absorber layers is studied. It is demonstrated that the composition impacts the degree of octahedral tilt, which is essential to restricting the transition to hexagonal phase impurities. Additionally, it is demonstrated that while a judicious mix of A-site cations can be used to stabilise the photoactive black phase of halide perovskites, it is challenging to achieve this homogeneously over large areas, necessitating a search for alternative or complementary approaches to stabilise perovskite via octahedral tilt. Using scanning electron diffraction (SED) studies, the spacegroup of additive-stabilised-CsPbI3 is demonstrated to be a low symmetry tilted γ-phase. Furthermore, using SED, the nanoscale structural landscape of mixed-phase CsPbI3 absorber layers is studied and it is demonstrated that both narrow-bandgap γ-phase and wide-bandgap δ-phase co-exist at the nanoscale, enabling stable and bright white-light emission. Overall, this thesis provides insights into the role of nanoscale structure in dictating the properties and behaviour of halide perovskites and offers rational guidelines for their optimisation and use in optoelectronic devices. Additionally, it is demonstrated that SED is a powerful tool for studying these materials at the atomic scale, allowing for the detailed characterisation of their structures and properties.

This thesis comprises three independent papers on applied microeconomics. The first chapter studies the impact of primary care provider mergers on quality in England. The second chapter investigates the effect of price dispersion on consumer search behavior, drawing evidence from the retail gasoline market in Greece. The final chapter builds on the second, studying the asymmetric price adjustment and the impact of market competition on the asymmetric price adjustment. The details of the three papers are summarized below: The Effects of General Practice Mergers on Quality in England The primary care market has witnessed a growing trend of provider consolidation through mergers and acquisitions, yet the implications of this concentration remain uncertain. This study addresses this gap by providing the first empirical evidence on the effects of provider mergers on quality using evidence from the English primary care market. By analyzing all provider mergers from 2014 to 2018, I find predominantly negative effects of mergers on quality. Clinical quality does not change at best, and patient satisfaction decreases dramatically. Notably, the impact on quality varies based on the size of the general practices involved. Mergers between large general practices show a detrimental impact on quality, while mergers between small general practices may yield quality benefits. Additionally, there is no difference in the quality impact between mergers involving parties in the same geographical market and those in different markets. An exploration of the mechanism reveals that mismanagement, rather than changes in market concentration, drives the observed decline in quality following mergers. The Effect of Competition and Price Dispersion on Search Behavior We investigate the impact of price dispersion on consumer search behavior, while credibly controlling for market structure. Using the retail gasoline market on isolated, oligopolistic markets, as defined by small Greek islands, we exploit an excise duty tax increase policy as a plausibly exogenous shock to price dispersion. We directly measure consumer search using the number of user visits to a price information platform and mobile application. We find that the tax shock increases price dispersion and that in turn causes a short term increase in consumer search. The effect of price dispersion on consumer search remains regardless of market competition level. Asymmetric Pass-Through and Competition We study the pass-through to retail prices of four major changes in taxes for petroleum products (three increases and one subsequent decrease). We use daily pricing data from gas stations on small Greek islands, which define isolated markets with different number of competitors. First, we find that, on average, the pass-through of the tax hikes is five times higher than for the tax decrease. Second, the pass-through of the tax hikes increases with the number of competitors, but that of the tax decrease does not vary with competition (asymmetric competition effect). Third, there is significant asymmetry in the speed of price adjustments. Fourth, the asymmetric adjustment of retail gasoline prices cannot be explained by tacit collusion and the evidence points to search as the most plausible explanation.

This thesis examines a group of freemen trading in coal at Newcastle upon Tyne in the sixteenth century known as the Hostmen’s Company. The Newcastle hostmen had established an unincorporated guild by 1508 and held the monopoly in the sale of coal from the town’s port during the rapid expansion of the Tyneside coal trade in the half-century from 1550. Their guild was granted legal status by the Crown in 1600. Existing research on the activities of the Newcastle hostmen in the sixteenth century offers important evidence about their monopoly but leaves open questions about the organization and membership of their guild. No comprehensive history of the Tudor hostmen has been attempted before. There has been no detailed assessment of their ascendancy or the trade of their principal members during a period of decisive change in the mining and sale of Tyneside coal and England’s transition to an industrial economy. This thesis uses little-explored town chamberlains’ accounts to investigate the origins, trading networks, family connections, and business activities of the Tudor hostmen for the first time. The accounts show that hosting coal at Newcastle was confined to a small group of citizens drawn mainly from the town’s mercantile and civic elite, and their widows. Some strangers, gentlemen, craftsmen, and yeomen also participated in the hosting trade. After the Dissolution of the Monasteries and the armed rebellions of the English Roman Catholic nobles the principal hostmen used their capital, political power, and religious connections to acquire the bulk of newly available mining land in the vicinity of Newcastle, creating a de facto monopoly in the production as well as the sale of coal. The hostmen shipped Tyneside coal to markets on the English coast, France, the Netherlands, and the Baltic Sea and had gained control over Newcastle’s governance by the mid-sixteenth century. This thesis shows the importance of two urban-industrial coal dynasties founded by the Newcastle corn merchants James Lawson (d. 1544) and Henry Anderson (d. 1559). Members of the Lawson-Anderson oligarchy dominated mining and hosting in Elizabethan Newcastle at a time when there was a more than three-fold increase in the volume of coal leaving the town’s port by the seaborne trade. They mined extensively in the vicinity of Newcastle on the banks of the River Tyne, created the most developed industrialized landscape in Elizabethan England, and built the two biggest integrated coal businesses in the town while continuing to trade as merchants in a wide variety of commodities. This thesis shows that the Lawson-Anderson oligarchy continued to dominate the Tyneside coal trade in the first half of the seventeenth century, though some of their members suffered heavy losses in the Civil War.

Self-organizing nanopatterns can enable economically competitive, industrially applicable light-harvesting platforms for thin-film solar cells. In this work, we present transparent solar cell substrates having quasiperiodic uniaxial nanowrinkle patterns with high optical haze values. The self-organized nanowrinkle template is created by controlled heat-shrinking of metal-deposited pre-stretched polystyrene sheets. A scalable UV nanoimprinting method is used to transfer the nanopatterns to glass substrates on which single-junction hydrogenated amorphous silicon p-i-n solar cells are subsequently fabricated. The structural and optical analyses of the solar cell show that the nanowrinkle pattern is replicated throughout the solar cell structure leading to enhanced absorption of light. The efficient broadband light-trapping in the nanowrinkle solar cells results in very high 18.2 mA/cm2 short-circuit current density and 9.5% energy-conversion efficiency, which respectively are 35.8% and 39.7% higher than the values obtained in flat-substrate solar cells. The cost- and time-efficient technique introduces a promising new approach to customizable light-management strategies in thin-film solar cells.

This study provides the first comprehensive overview of the sustainability performance of the hotel sector in the Himalayan region: Sagarmatha National Park and Buffer Zone, using both environmental, economic, and technical criteria. In particular, the performance of 45 buildings in this region were measured and quantified in terms of life cycle based carbon footprint, life cycle costs, heat loss rate, number of guests, energy consumption, and area. Buildings were classified into three types: traditional, semi-modern and modern. The statistical analysis included testing for significant differences between such categories by means of ANOVA, and determination of the correlation between the same parameters. Results show a significant difference between the buildings’ total carbon footprint and operation stage carbon footprint while, there is no significant difference between the buildings’ life cycle costs. Traditional buildings have on average the largest carbon footprint and life-cycle cost over the typical building lifespan of 50 years of building lifespan. The ANOVA tests highlight how heat loss rate, size of the building and number of tourists in the hotels are significantly different across the building types. A strong positive correlation is observed between environmental impact, economic impact and energy consumption for the household activities, and a negative correlation with the number of guests and building size. By considering several buildings, this study allows to draw new and more general conclusions about effective sustainability strategies in the whole hotel sector in the Himalayan region. In particular, it shows that reducing impacts in the operation stage should be highly prioritized, focusing on reducing energy consumption and heat loss and shifting to the use of renewable energy sources.

Formate production via both CO2 reduction and cellulose oxidation in a solar-driven process is achieved by a semiartificial biohybrid photocatalyst consisting of immobilized formate dehydrogenase on titanium dioxide (TiO2|FDH) producing up to 1.16±0.04 mmolformate gTiO2-1 in 24 hours. Isotopic labelling experiments with 13C-labelled substrates support the mechanism of stoichiometric formate formation through both redox half-reactions. TiO2|FDH was further immobilized on hollow glass microspheres to perform more practical floating photoreforming allowing vertical solar light illumination with optimal light exposure of the photocatalyst to real sunlight. Enzymatic cellulose depolymerization coupled to the floating photoreforming catalyst generates 0.36±0.04 mmolformate mirr-2 after 24 h. This work thus presents simultaneous solar-driven valorization of waste streams, demonstrates the advantages of biohybrid photocatalysts in photoreforming for the first time and will provide inspiration for the development of future semi-artificial waste-to-chemical conversion strategies.

This thesis grapples with two distinct but interrelated issues: Indigenous climate sovereignty and the imagination of climate apocalypse. It is particularly concerned with how these two themes intersect in the High North, a landscape continually constructed as a periphery and frontier. In the pages that follow, I explore the misalignments between colonial projections of the land and its people, and the lived experiences of climate change and colonialism as I encountered them in two Alaska Native villages. This thesis is rooted in a multisited ethnography in Norton Sound, in Western Alaska. The ethnographic object of this study is not Alaska Native communities, but rather the forms of politics that connect rural Indigenous governments to colonial centres of power in the United States Federal government. In that sense, the research presented here is as much a political ethnography as it is an environmental one. The conclusions presented in this thesis are fourfold. 1) Marginalised Alaska Native communities face a neo-colonial pressure whereby, in order to receive assistance, they are required to adopt the bureaucratic forms and logic of their colonisers; 2) the manner in which the Arctic has been enlisted to support popular apocalyptic climate discourse echoes the modernist role the region played in 19th- and 20th-century constructions, as a mirror for urban humanity; 3) social scientists and humanities scholars have broadly neglected the importance of situating knowledge about climate change and ecological futures, and instead resort to sweeping, planetary gestures; and 4) urban narratives of climate apocalypse offer a potent antidote to political alienation.