Sökresultat

The principal purposes of the studies reported in this thesis were to develop new methods to make computerised decision support systems in medicine both more reliable and fully automated. These aims were pursued in the belief that the solution to these problems will lead to an increased clinical use of such systems resulting in benefit to both patient and physician. In the first two studies, meth

Hazardous radioactive sources out of regulatory control are referred to as orphan sources. Focussing on gamma-emitting orphan sources, this thesis describes methods that can be used in mobile gamma-ray spectrometry to perform real-time discrimination between an actual source signal and the signal due to the natural radiation background. Two categories of methods for orphan source detection are pre

The current form-giving activity in industrial design is characterized by explorations that depend on the individual capability to mentally manipulate a solution space from which to select and express the intended result. Industrial designers frequently rely on artistic experimentation, aesthetic inspiration, or design briefs. These points of departure often result in satisfactory results, but the

The aim of this work was to investigate the dosimetric effects of removing the flattening filter from conventional C-arm medical linear accelerators. In conventional linear accelerators used for radiotherapy, a flattening filter is positioned in the beam line to provide a uniform lateral dose profile at a specified depth in water. However, for some radiotherapy treatments, a uniform lateral dose p

How are access to asylum and other forms of extraterritorial protection regulated in the European Union? Is the EU acquis in these areas in conformity with international law? What tools does international law offer to solve conflicts between them? And, finally, is law capable of bridging the foundational oppositions embedded in migration and asylum issues? This work combines the potential of legal

In the last two decades, phase-contrast magnetic resonance imaging (PC-MRI) has evolved from two-dimensional velocity and flow measurements to volumetric, time-resolved depictions of velocity fields (4D PC). The acquisition of time-resolved velocity fields allows flow visualisations that might provide better understanding of the dynamics of the cardiac system. Because 4D PC is increasingly being u

In the normal functioning organism, there is a balance between cell proliferation, cell differentiation, and cell death. An imbalance in these processes results in different diseases. This thesis concerns the imbalance where there is too little cell death and cell differentiation with increased cell proliferation. The result is uncontrolled cell proliferation resulting in the development of cancer

Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly w

This thesis deals with models of flat plate collectors, transparent insulation and efficiency factors. An equation for the energy output from a glazed flat plate collector is derived by modelling the collector efficiency factor, F´ as the sum of a constant and a temperature dependent part. An alternative way of testing a flat plate collector, based on this model, is suggested. A complete set of a

It is commonly believed that we live in a culture that is increasingly permeated by visual images. One category of images that we encounter everyday in different media, and that constitutes a large and growing part of media content, is advertisements. Advertisements also have a specific purpose and the images represent, make meaning of, and convey sentiments about phenomena. In this dissertation,

The objective of this thesis is to study the application of ventilation in schools buildings. A number of studies of the application of different forms of ventilation are presented. The main part of the thesis focuses on window opening in a classroom. Analytical models for calculation of the air change caused by window airing are proposed. The models are intended to be a tool for designers and occ

This doctoral thesis treats three issues in control engineering related to relay feedback and multivariable control systems. Linear systems with relay feedback is the first topic. Such systems are shown to exhibit several interesting behaviors. It is proved that there exist multiple fast relay switches if and only if the sign of the first non-vanishing Markov parameter of the linear system is pos

A major aim initially was to create a forum for reflective dialogue on the preschool professions and how it is experienced on a daily basis, so as to be able to investigate how members of the preschool staff construct their professional subject. The following are major questions that were posed: How do preschool staff members talk about themselves, their profession and their work? In what way does

Sierra Leone is a small country with rich mineral resources such as diamonds, bauxite, gold and iron ore. Other resources include fishing, forestry and fertile agricultural land, which enable people to farm without any sophisticated methods of mechanization. Nevertheless, with all its wealth in resources, the country is relatively poor and is one of the least developed countries in the Sub-Saharan

Lignin is a potential biofuel which can be extracted from kraft cooking liquor. Lignin can also prove valuable as a speciality chemical. By extracting lignin potential economical revenue can be gained by pulp mills, as well as technical benefits such as easier delignification and bleaching. The subject of this work was the extraction of lignin from kraft cooking liquor using ceramic ultrafiltrati

A thermodynamic model for electrolyte solutions has been derived for binary and multicomponent solutions up to very high molalities. The model was extensively tested on 163 binary aqueous electrolyte systems up to very high molalities, and the results show that the model represents mean ionic activity coefficients and osmotic coefficients very accurately. The model parameters vary significantly be

One of the noticeable trends in recent years is that products have received increasing attention in environmental policy. The focus on products and their life cycle impacts is often referred to as ?life cycle thinking?. This implies a shift away from the traditional focus on production processes and the environmental impacts of point-source pollution, towards a stronger focus on emissions from the

The mean by which a gas turbine combustor is cooled is of major importance for the efficiency and emission performance of the machine. The trends of increasing top cycle temperature and leaner combustion have also been accompanied by a need of efficient use of the cooling air. Traditional cooling schemes such as film cooling are associated with high coolant flow rates and unacceptable emission lev

Low temperature has a large impact on the survival and distribution of plants. Interactive effects with high irradiance lead to cold-induced photoinhibition, which may impact on the establishment and growth of tree seedlings. In this thesis, novel approaches are applied for relating the spatial variability in low temperature and irradiance to photosynthetic performance and growth of tree seedlings