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The purpose of this study is to identify the factors influencing pupils when they individually solve problems in mathematics in grades 4-9 in the compulsory school (ages: 10-16 years). The method that has been used is an analyses of the solutions of 25 problems given to each grade. Some of the problems were the same in all grades and about 100 pupils participated in each grade. Through an examinat
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
The recombinant DNA techniques have made it possible to produce many different proteins for a wide range of applications. The vector encoding for the recombinant protein is often inserted in the bacterium E. coli as it is a well studied and a well-known organism. To achieve a high productivity, it is important to reach a high cell density. This is obtained through fed-batch operation where the nut
The thesis comprises an introductory chapter and four research papers. The introductory chapter provides a brief overview of recent economic growth performance in Africa, places the individual papers into a coherent context, summarizes the main findings, and discusses their relevance for economic policy. The first paper, The Role of Capital Accumulation, Adjustment and Structural Change for Take-
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,
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
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
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
The modeling work developed in this thesis can be divided in two main areas of investigations: autoignition related to spark ignition engine and combustion and emissions formation in relation to diesel engines. A first version of a detailed kinetics engine simulation program, extended to handle full cycle calculations, was employed in order to demonstrate the strong effect that nitric oxide from
Diesel engine developers are facing major challenges when meeting future demands on NOx and particulate emissions. The exhausts after treatment systems are rapidly improving and the technologies available in a few years will be capable of cutting emission levels close to the demanded levels. However, in order to reach the low emissions required in a long-lasting, cost effective way, the potential
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
This dissertation discusses the personal implications of the early consequences of rheumatoid arthritis, how they effect the person's working life and how they are dealt with. In this qualitative study thematized interviews are used. Twenty-three persons, recently diagnosed with rheumatoid arthritis, were interviewed twice, two years apart. The study is influenced by an interactionist perspective
The role of stochasticity throughout many biophysical systems is of great importance. From evolution to foraging, from the spreading of viruses to cell fate, all hinge in one way or another on inherent stochasticity. The aim of this thesis is to explore the tools often used to quantify randomness in nature, and employ these tools on a selected range of biophysical systems (Papers I-IV). In these p
Helicobacter pylori is a human pathogen strongly associated with chronic type B gastritis, peptic ulcer disease, gastric cancer and MALT lymphoma. Our aims were to establish a mouse model of H. pylori infection, to study pathogenesis of gastritis and gastric cancer and to investigate new treatment strategies in this model. Both spiral and coccoid forms of H. pylori strains 17874, 25 and 553/93 cau
Tortuguero National Park in Costa Rica hosts nesting by four species of highly migratory and endangered sea turtles (green, hawksbill, leatherback and loggerhead turtles). Sea turtle research at Tortuguero has been continuous since Dr. Archie Carr began studies in the 1950?s. This dissertation aims to clarify the Tortuguero sea turtles? post-nesting migrations, nesting trends and survival threats.
This book attempts to answer the question of how it is possible that Christianity in the beginning of the second century C.E. had developed into a non-Jewish, Gentile religion. Since Christianity was originally one of many Jewish factions within the diversified Judaism of the period, and one that even primarily seems to have directed its attention to the people of Israel, the problem of its separa
The crystalline properties of starch constitutes a puzzling area of research. Our understanding of the crystalline structure of amylopectin, that is the crystalline component in starch, is based on the observations from investigations on modified amylose. The first part of this thesis includes a discussion of the unit cells (the smallest crystalline units) suggested in the literature. The differen
A continuing use of fossil fuels will accelerate global warning and result in severe consequences for the environment and thereby also us. Development of alternative, sustainable and environmentally friendly energy sources is therefore crucial. One approach is to create an artificial photosynthetic system that converts sunshine into fuel (e.g. hydrogen gas) by splitting water molecules. However, i
