| 1. |
- Masterton, George, 1978-
(författare)
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Objective Chance : A Study in the Lewisian Tradition
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation explores the notion of objective chance as reasonable degree of belief given what might loosely be called our ultimate evidence. The goal is to develop a notion of objective chance that is broadly Humean: where chance ascriptions are construed as projected, De Dicto, physical modalities. It builds, in large part, on the work of David Lewis on objective chance and the metaphysics of indeterminism. It is argued that Lewis and the sciences take objective chance to measure the degree to which a proposition/sentence is physically determined true. These measures of determinacy are analysed in the Lewisian manner as a special kind of credence, an analysis justified by Lewis’ Principal Principle. This analysis faces several problems: the Principal Principle may not be generally applicable due to vicious circularities, chances so conceived may be incompatible with Humean supervenience, and the analysis itself may be uninformative. This dissertation addresses each of these concerns in turn. It proposes a novel trivial chance solution to the first problem and then extends this to solve the second problem, often referred to as the Bug. The aim of this text with respect to the Bug is not to provide a novel cure, but to increase our understanding of the Bug and why the standard medicine is the best on offer. Toward the end of the dissertation the informativity of the analysis is increased by an in depth study of the analysans. This study culminates in moving from Lewis’ objectified credences to credence conditional on an indexical as the analysans for objective chance.
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| 2. |
- Shakeri Yekta, Sepehr, 1982-
(författare)
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Chemical Speciation of Sulfur and Metals in Biogas Reactors : Implications for Cobalt and Nickel Bio-uptake Processes
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A balanced supply of micronutrients, including metals such as iron (Fe), cobalt (Co), and nickel (Ni), is required for the efficient and stable production of biogas. During biogas formation, the uptake of micronutrient metals by microorganisms is controlled by a complex network of biological and chemical reactions, in which reduced sulfur (S) compounds play a central role. This thesis addresses the interrelationship between the overall chemical speciation of S, Fe, Co, and Ni in relation to the metals bio-uptake processes. Laboratory continuous stirred tank biogas reactors (CSTBR) treating S-rich grain stillage, as well as a number full-scale CSTBRs treating sewage sludge and various combinations of organic wastes, termed co-digestion, were considered. Sulfur speciation was evaluated using acid volatile sulfide (AVS) extraction and S X-ray absorption near edge structure (XANES). The chemical speciation of Fe, Co, and Ni was evaluated through the determination of aqueous metals and metal fractions pertaining to solid phases, as well as kinetic and thermodynamic analyses (chemical speciation modelling). The relative Fe to S content in biogas reactors, which in practice is regulated through the addition of Fe for the purpose of sulfide removal or prior to the anaerobic digestion of sewage sludge, is identified as a critical factor for the chemical speciation and bio-uptake of metals. In the reactors treating sewage sludge, the quantity of Fe exceeds that of S, inducing Fe(II)-dominated conditions under anaerobic conditions, while sulfide dominates in the co-digestion and laboratory reactors due to an excess of S over Fe. Under sulfide-dominated conditions, chemical speciation of the metals is regulated by hydrogen sulfide and the formation of metal sulfide precipitates, which in turn restrict the availability of metals for microorganisms. However, despite the limitations set by sulfide, aqueous concentrations of different Co and Ni species were shown to be sufficient to support metal acquisition by the microorganisms under sulfidic conditions. Comparatively, the concentrations of free metal ions and labile metal-phosphate and -carbonate complexes in aqueous phase, which directly participate in bio-uptake processes, are higher under Fe-dominated conditions. This results in an enhanced metal adsorption on cell surfaces and faster bio-uptake rates. It is therefore suggested that the chemical speciation and potential bioavailability of metals may be controlled through adjustments of the influent Fe concentration in relation to S content. The results also indicated that the pool of metal sulfides in the biogas reactors could be regarded as a source of metals for microbial activities. Thus, the recovery and utilisation of this fraction of metals may be considered as a measure with which to minimise the metal dosing concentrations to CSTBRs.
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| 3. |
- Stenlund, Karin, 1950-
(författare)
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Läsning på mellanstadiet : En studie med fokus på elevers läsförmåga
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study describes the reading ability of 26 middle school students, and the ways in which their reading development is supported in two different classrooms. In order to scrutinize results of students at different reading levels, three focus students were selected.This thesis has four aims. One is to use tests to examine the students’ reading ability as regards their decoding skills and reading comprehension as well as to study other cognitive skills related to reading ability. Another is to describe the students’ reading ability and attitudes towards reading from their own as well as their teachers’ perspectives. A third aim is to analyze how the results of different parts of the study are related to one another. The fourth and final aim is to analyze the classroom activities with a special focus on how reading ability is supported.The study combines quantitative analyses of the students’ reading ability with qualitative analyses of classroom activities. The quantitative sections of the study include various reading tests as well as the teachers’ assessment of the students’ reading development and their answers to selected questions in a student questionnaire concerning their view on reading.The results reveal that several of these students haven´t automated their decoding ability in Grade 4, but that nevertheless most of the students attain their grade level in a reading comprehension test in Grade 4 as well as the goals of a national reading test in Grade 5. However, most of the questions in these two tests require answers that can be explicitly found in the text and do not require any deeper reading comprehension such as inference making for instance. The results also show that these students are unable to assess whether reading is easy for them, but can assess their own reading ability if the purpose is to compare their reading skills with their classmates. The classroom observations indicate that despite quite extensive text work in the classrooms, students who need to develop their decoding abilities receive little support, and that although classroom work focusing on text comprehension is quite frequent, this does not often include deeper levels such as inference making.
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