From interannual to decadal: 17 years of boundary current transports at the exit of the Labrador Sea

Over the past 17 years, the western boundary current system of the Labrador Sea has been closely observed by maintaining the 53°N observatory (moorings and shipboard station data) measuring the top-to-bottom flow field offshore from the Labrador shelf break. Volume transports for the North Atlantic Deep Water (NADW) components were calculated using different methods, including gap filling procedures for deployment periods with suboptimal instrument coverage. On average the Deep Western Boundary Current (DWBC) carries 30.2 ± 6.6 Sv of NADW southward, which are almost equally partitioned between Labrador Sea Water (LSW, 14.9 ± 3.9 Sv) and Lower North Atlantic Deep Water (LNADW, 15.3 ± 3.8 Sv). The transport variability ranges from days to decades, with the most prominent multiyear fluctuations at interannual to near decadal time scales (±5 Sv) in the LNADW overflow water mass. These long-term fluctuations appear to be in phase with the NAO-modulated wind fluctuations. The boundary current system off Labrador occurs as a conglomerate of nearly independent components, namely, the shallow Labrador Current, the weakly sheared LSW range, and the deep baroclinic, bottom-intensified current core of the LNADW, all of which are part of the cyclonic Labrador Sea circulation. This structure is relatively stable over time, and the 120 km wide boundary current is constrained seaward by a weak counterflow which reduces the deep water export by 10–15%

Multi-Agent Modeling of Risk-Aware and Privacy-Preserving Recommender Systems

Recent progress in the field of recommender systems has led to increases in the accuracy and significant improvements in the personalization of recommendations. These results are being achieved in general by gathering more user data and generating relevant insights from it. However, user privacy concerns are often underestimated and recommendation risks are not usually addressed. In fact, many users are not sufficiently aware of what data is collected about them and how the data is collected (e.g., whether third parties are collecting and selling their personal information). Research in the area of recommender systems should strive towards not only achieving high accuracy of the generated recommendations but also protecting the user’s privacy and making recommender systems aware of the user’s context, which involves the user’s intentions and the user’s current situation. Through research it has been established that a tradeoff is required between the accuracy, the privacy and the risks in a recommender system and that it is highly unlikely to have recommender systems completely satisfying all the context-aware and privacy-preserving requirements. Nonetheless, a significant attempt can be made to describe a novel modeling approach that supports designing a recommender system encompassing some of these previously mentioned requirements. This thesis focuses on a multi-agent based system model of recommender systems by introducing both privacy and risk-related abstractions into traditional recommender systems and breaking down the system into three different subsystems. Such a description of the system will be able to represent a subset of recommender systems which can be classified as both risk-aware and privacy-preserving. The applicability of the approach is illustrated by a case study involving a job recommender system in which the general design model is instantiated to represent the required domain-specific abstractions

Simulating Nature : A philosophical study of computer-simulation uncertainties and their role in climate science and policy advice

Computersimulatie in wetenschap en beleid Onzekerheden in computersimulaties staan zowel in de wetenschap als in de politiek ter discussie. Zo wordt reeds sinds de introductie van computersimulatie in de wetenschap gediscussieerd over de status van simulatiewetenschap ten opzichte van experimentele en theoretische wetenschap. En in politieke kringen worden vraagtekens gezet bij het gebruik van onzekere resultaten van computersimulatie in overheidsbeleid. De praktijk van wetenschappelijke simulatie en de rol van simulatie in wetenschap en beleid geven aanleiding tot verschillende filosofische vragen. Bijvoorbeeld: welke specifieke typen van onzekerheid zijn verbonden aan wetenschappelijke simulatie? Wat zijn de verschillen en overeenkomsten tussen simulatie-onzekerheid en experimentele onzekerheid? En: wat zijn gepaste manieren om onzekerheden in wetenschappelijke simulatie te beoordelen en te communiceren in beleidsadvisering. Arthur Petersen doet voorstellen voor een typologie van onzekerheid en een methode van omgaan met onzekerheid in wetenschappelijke beleidsadvisering. Één probleem wordt door Petersen in het bijzonder belicht, namelijk de door de mens veroorzaakte klimaatverandering. Heeft de mens momenteel een aanzienlijke invloed op het klimaat? Volgens beleidsmakers hebben wetenschappers die vraag in de context van het Intergovernmental Panel on Climate Change (IPCC) positief beantwoord. Hoe komen wetenschappers tot zulke conclusies en waarom vertrouwen beleidsmakers hen? De eerder opgedane filosofische inzichten over simulatie-onzekerheid worden door Petersen toegepast in een evaluatie van de omgang met klimaatmodelonzekerheid door het IPCC. De volgende twee specifieke onderzoeksvragen worden behandeld: welke specifieke typen van simulatie-onzekerheid zijn verbonden aan de toeschrijving van klimaatverandering aan menselijke invloeden? En: zijn deze onzekerheden op een gepaste manier beoordeeld en gecommuniceerd in het derde assessmentrapport van het IPCC (2001)?Radder, J.A. [Promotor]Kirschenmann, P.P. [Copromotor

Monitoring climate for the effects of increasing greenhouse gas concentrations

Roger A. Pielke, Timothy G.F. Kittel, co-editors.Includes bibliographical references.A compendium of papers presented at a workshop sponsored on August 26-28, 1987 by the Cooperative Institute for Research in the Atmosphere

Coastal marine heatwaves: Understanding extreme forces

Philosophiae Doctor - PhD (Biodiversity and Conservation Biology)Seawater temperature from regional to global scale is central to many measures of biodi- versity and continues to aid our understanding of the evolution and ecology of biolog- ical assemblages. Therefore, a clear understanding of the relationship between marine biodiversity and thermal structures is critical for effective conservation planning. In the an- thropocene, an epoch characterised by anthropogenic forcing on the climate system, future patterns in biodiversity and ecological functioning may be estimated from projected climate scenarios however; absent from many of these scenarios is the inclusion of extreme thermal events, known as marine heatwaves (MHWs). There is also a conspicuous absence in knowl- edge of the drivers for all but the most notorious of these events. Before the drivers of MHWs along the coast of South Africa could be determined, it was first necessary to validate the 129 in situ coastal seawater temperature time series that could be used to this end. In doing so it was found that time series created with older (longer), lower precision (0.5 Degrees Celsius) instruments were more useful than newer (shorter) time series produced with high precision (0.001 Degrees Celsius) instruments. With the in situ data validated, a history of the occurrence of MHWs along the coastline (nearshore) was created and compared against MHWs detected by remotely sensed data (offshore). This comparison showed that the forcing of offshore temperatures onto the nearshore was much lower than anticipated, with the rates of co-occurrence for events between the datasets along the coast ranging from 0.2 to 0.5. To accommodate this lack of consistency between datasets, a much larger mesoscale area was then taken around southern Africa when attempting to determine potential mesoscale drivers of MHWs along the coast. Using a self organising-map (SOM), it was possible to organise the synoptic scale oceanographic and atmospheric states during coastal MHWs into discernible groupings. It was found that the most common synoptic oceanographic pattern during coastal MHWs was Agulhas Leakage, and the most common atmospheric pattern was anomalously warmoverland air temperatures.With these patterns known it is now necessary to calculate how often they occur when no MHW has been detected. This work may then allow for the development of predictive capabilities that could help mitigate the damage caused by MHWs

Mar a chuala mi: remembering and telling Gaelic Stories: a study of Brian Stewart

This thesis is a study of one storyteller, Brian Stewart, and his storytelling. The aim of the project is to understand and elucidate the way in which one storyteller remembers and tells stories. The methods used in the study are the direct questioning of the storyteller about his relationship to storytelling, as well as a detailed comparative analysis of the stories themselves. As such, the thesis is as much concerned with the storyteller's own beliefs about storytelling as with the evidence supplied by the stories.In the Introduction I discuss the aims of the project and explain its genesis and my reasons for choosing the methods employed.In Chapter One I discuss questions about the nature of Gaelic storytelling, and review the scholarly literature related to this study.In Chapter Two I discuss Mr. Stewart's life story, relying heavily on comments and material recorded from the storyteller himself. This discussion concentrates on topics which Mr. Stewart has emphasised in the course of interviews, including boyhood memories of travelling and the travelling life, related activities such as tin-smithing and horse-dealing, and storytelling.In Chapter Three I consider Brian Stewart's development as a storyteller: his knowledge and experience of storytelling, and his own comments on how he learned and remembered stories, how his memory works, and on storytelling practices in general.Chapter Four consists of an analysis of the stories themselves. Here I use close to 40 separate recordings of nine different stories recorded between 1958 and 1995, comparing different recordings of the same stories in terms of their episodic structure, content, and use of language. The aim of the comparison is to discover patterns of variation and similarity between the story versions, and so to identify features of Brian Stewart's storytelling and to better understand his storytelling ethos. The Conclusion summarises the overall findings of the thesis, and points to some possibilities for future scholarly inquiry in this field.Following the main body of the thesis, transcriptions of the recorded story versions discussed in Chapter Four are contained in an appendix, as is other background information on the stories as may be useful to other scholars

BUILT UTOPIAS IN THE COUNTRYSIDE: THE RURAL AND THE MODERN IN FRANCO’S SPAIN

Anchored by Hüppauf and Umbach’s notion of Vernacular Modernism and focusing on architecture and urbanism during Franco’s dictatorship from 1939 to 1975, this thesis challenges the hegemonic and Northern-oriented narrative of urban modernity. It develops arguments about the reciprocal influences between the urban and the rural that characterize Spanish modernity, and analyzes the intense architectural and urban debates that resulted from the crisis of 1898, as they focused on the importance of vernacular architecture, in particular the Mediterranean one, in the definition of an “other modernity.†This search culminated before 1936 with the “Lessons of Ibiza,†and was revived at the beginning of the 1950s, when architects like Coderch, Fisac, Bohigas, and the cosigners of the Manifiesto de la Alhambra brought back the discourse of the modern vernacular as a politically acceptable form of Spanish modernity, and extended its field of application from the individual house and the rural architecture to the urban conditions, including social and middle-class housing. The core of the dissertation addresses the 20th century phenomenon of the modern agricultural village as built emergence of a rural paradigm of modernity in parallel or alternative to the metropolitan condition. In doing so, it interrogates the question of tradition, modernity, and national identity in urban form between the 1920s and the 1960s. Regarding Spain, it studies the actuation of the two Institutes that were created to implement the Francoist policy of post-war reconstruction and interior colonization—the Dirección General de Regiones Devastadas, and the Instituto Nacional de Colonización. It examines the ideological, political, urban, and architectural principles of Franco’s reconstruction of the devastated countryside, as well as his grand “hydro-social dream†of modernization of the countryside. It analyzes their role in national-building policies in liaison with the early 20th-century Regenerationist Movement of Joaquín Costa, the first works of hydraulic infrastructure under Primo de Rivera, and the aborted agrarian reform of the Second Republic. Inspired by the Zionist colonization of Palestine and Mussolini’s reclaiming of the Pontine Marshes, Falangist planners developed a national strategy of “interior colonization†that, along with the reclamation and irrigation of extensive and unproductive river basins, entailed the construction of three hundred modern villages or pueblos between 1940 and 1971. Each village was designed as a “rural utopia,†centered on a plaza mayor and the church, which embodied the political ideal of civil life under the nationalcatholic regime and evolved from a traditional town design in the 1940s to an increasingly abstract and modern vision, anchored on the concept of the “Heart of the City†after 1952. The program was an important catalyst for the development of Spanish modern architecture after the first period of autarchy and an effective incubator for a new generation of architects, including Alejandro de la Sota, José Luis Fernández del Amo, and others. Between tradition and modernity, these architects reinvented the pueblos as platforms of urban and architectonic experimentation in their search for a depurated rural vernacular and a modern urban form. Whereas abstraction was the primary design tool that Fernández del Amo deployed to the limits of the continuity of urban form, de la Sota reversed the fundamental reference to the countryside that characterizes Spanish surrealism to bring surrealism within the process of rural modernization in Franco’s Spain

The acquisition of literacy in Gaelic-medium primary classrooms in Scotland

This thesis analyses the factors affecting the acquisition of literacy in Gaelic-medium primary classrooms, including teaching techniques, availability of resources, and support for language development. In order to investigate this issue thoroughly, the background for the study includes an overview of the sociolinguistic situation of Scottish Gaelic, comparison to other minority language revitalisation efforts, discussion of the theories and practice of bilingualism and bilingual education, and an in-depth look at literacy acquisition, from perceptions of literacy and its value to the mechanics of reading in both a first and a second language. The core of the thesis presents extended observational data from seven case-study classrooms. The targeted population is Primary 1 to 3 pupils as this is the intensive period of reading instruction; the research focus is on literacy in Gaelic as the amount of English at this stage is negligible. Interviews and questionnaires involving education authorities, teachers, and parents supplement this data and emphasise the qualitative, ethnographic approach. The specific results are placed in the broader context of the Scottish education system and the Gaelic revitalisation movement. The analysis assesses the effectiveness of literacy acquisition in Gaelic-medium education and addresses some of the challenges related to further development. This thesis concludes that while significant progress has been made in the teaching of literacy in Gaelic-medium education, there are several points that are cause for concern, including the nature of teacher training, the provision of sufficient and appropriate resources, and the amount of extra-curricular reading taking place. Examples of "best practice" from the case-study classrooms are provided as possible solutions to these problems

Clearing the air: essays on the economics of air pollution

Exposure to air pollution is a leading cause of premature death worldwide. An increasing part of air pollution results from industrial activity and the production of energy. When unregulated, emissions of air pollutants constitute a market failure as polluters do not bear the costs imposed on society at large. My dissertation develops empirical methods to test the effectiveness and distributional effects of environmental policies designed to address this externality. To do so, I apply econometrics and data science techniques on large datasets from cutting-edge research in environmental science and engineering that I match with microeconomic data. The dissertation makes use of new datasets on air pollution derived from satellite imagery, as well as micro-level data on power plant operations and housing transactions across the United States. Chapter 1 assembles unit-level data to disentangle the factors that led US power plants to achieve the unprecedented reductions in emissions of the past fifteen years. I calculate the costs incurred by the electricity generation sector and compare these costs to the correspond- ing health benefits. In hedonic regressions, I use these shocks to emissions to estimate the demand for clean air with micro-level data on housing transactions. Chapter 2 studies the causal impacts and evaluates the distributional effects of stringent emissions markets that were put in place to target power plants emissions of air pollutants in the Eastern US. Chapter 3 uses new satellite imagery to document the inequalities in the exposure to air pollution in American cities and their recent evolutions