| 1. |
- A Asif, Farazee M, 1980-
(author)
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Circular Manufacturing Systems : A development framework with analysis methods and tools for implementation
- 2017
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Doctoral thesis (other academic/artistic)abstract
- The society today lives on the philosophy of ‘take-make-use-dispose.’ In the long run, this is not sustainable as the natural resources and the waste carrying capacity of the earth are limited. Therefore, it is essential to reduce dependency on the natural resources by decoupling the growth from the consumption. In this venture, both the society and the manufacturing industry have a vital role to play. The society needs to shift towards Circular Economy that rests upon the philosophy of ‘take-make-use-reuse’ and the manufacturing industry has to be a major stakeholder in this shift. Despite being proven to be both economically and environmentally beneficial, successful examples of circular systems are few today. This is primarily due to two reasons; firstly, there is a lack of systemic and systematic approach to guide industries and secondly, there is a lack of analysis methods and tools that are capable of assessing different aspects of circular manufacturing systems. Taking on to these challenges, the objective of this research is to bring forward a framework with methods and decision support tools that are essential to implement circular manufacturing systems. The initial conceptual framework with the systemic approach is developed based on extensive review and analysis of research, which is further adapted for industrial implementation. Systematic analysis methods, decision support and implementation tools are developed to facilitate this adaptation. This development has been supported by four cases from diverse manufacturing sectors. Behind each decision support tool, there are analysis methods built upon mainly system dynamics principles. These tools are based on simulation platforms called Stella and Anylogic. Among other things, these tools are capable of assessing the performance of closed-loop supply chains, consequences of resource scarcity, potential gains from resource conservation and overall economic and environmental performance of circular manufacturing systems.
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| 2. |
- A. M. Naiini, Maziar, 1980-
(author)
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Horizontal Slot Waveguides for Silicon Photonics Back-End Integration
- 2014
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Doctoral thesis (other academic/artistic)abstract
- This thesis presents the development of integrated silicon photonic devices. These devices are compatible with the present and near future CMOS technology. High-khorizontal grating couplers and waveguides are proposed. This work consists of simulations and device design, as well as the layout for the fabrication process, device fabrication, process development, characterization instrument development and electro-optical characterizations.The work demonstrates an alternative solution to costly silicon-on-insulator photonics. The proposed solution uses bulk silicon wafers and thin film deposited waveguides. Back-end deposited horizontal slot grating couplers and waveguides are realized by multi-layers of amorphous silicon and high-k materials.The achievements of this work include: A theoretical study of fully etched slot grating couplers with Al2O3, HfO2 and AIN, an optical study of the high-k films with spectroscopic ellipsometry, an experimental demonstration of fully etched SiO2 single slot grating couplers and double slot Al2O3 grating couplers, a practical demonstration of horizontal double slot high-k waveguides, partially etched Al2O3 single slot grating couplers, a study of a scheme for integration of the double slot Al2O3 waveguides with selectively grown germanium PIN photodetectors, realization of test chips for the integrated germanium photodetectors, and study of integration with graphene photodetectors through embedding the graphene into a high-k slot layer.From an application point of view, these high-k slot waveguides add more functionality to the current silicon photonics. The presented devices can be used for low cost photonics applications. Also alternative optical materials can be used in the context of this photonics platform.With the robust design, the grating couplers result in improved yield and a more cost effective solution is realized for integration of the waveguides with the germanium and graphene photodetectors.
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| 3. |
- A. Manneh, Ilana, 1970-
(author)
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Supporting Learning and Teaching of Chemistry in the Undergraduate Classroom
- 2019
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Doctoral thesis (other academic/artistic)abstract
- There is agreement in research about the need to find better ways of teaching chemistry to enhance students’ understanding. This thesis aims to contribute to the understanding of how we better support teaching and learning of undergraduate chemistry to make it meaningful and intelligible for students from the outset. The thesis is concerned with examining the interactions between student, specific content and teacher in the undergraduate chemistry classroom; that is, the processes making up the three relations of the didactic triangle. The data consists of observations of students and tutors during problem-solving activities in an introductory chemistry course and interviews with graduate students.Systematic analyses of the different interactions between the student, the chemistry content, and the tutor are made using the analytical tool of practical epistemology analysis. The main findings of the thesis include detailed insights into how undergraduate chemistry students deal with newly encountered content together with didactic models and concrete suggestions for improved teaching and for supporting continuity and progression in the undergraduate chemistry classroom. Specifically, I show how students deal with the chemistry content through a complex interaction of knowledge, experiences, and purposes on different levels invoked by both students and tutors as they interact with each other. Whether these interactions have a positive or negative effect on students’ learning depends on the nature of knowledge, experiences and purposes that were invoked. Moreover, the tutor sometimes invoked other purposes than the ones related to the task at hand for connecting the activity to the subject matter in general. These purposes were not always made continuous with the activity which resulting in confusion among students. The results from these analyses were used for producing hypotheses and models that could support continuity and progression during the activity. The suggested models aim to make the content more manageable and meaningful to students, enabling connections to other experiences and purposes, and helping teachers and tutors to analyze and reflect on their teaching. Moreover, a purpose- and activity-based progression is suggested that gives attention to purposes in chemistry education other than providing explanations of chemical phenomena. The aim of this ‘progression in action’ is to engage students in activities were they can see the meaning of chemical concepts and ideas through their use to accomplish different chemical tasks. A general conclusion is that detailed knowledge about the processes of teaching and learning is important for providing adequate support to both undergraduate students and university teachers in the chemistry classroom.
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| 4. |
- A Monfared, Behzad, 1983-
(author)
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Magnetic Refrigeration for Near Room-Temperature Applications
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Refrigeration plays a crucial role in many different sectors and consumes about 17% of the electricity produced globally. This significant energy consumption implies large share of refrigeration in primary energy consumption and other environmental impacts. In addition to the environmental impacts associated with energy consumption, the vapor-compression systems contribute in global warming due to the release of their gaseous refrigerants into the atmosphere. As an alternative technology for near room-temperature applications, magnetic refrigeration is proposed by some researchers to eliminate the release of gaseous refrigerants into the atmosphere and to reduce the energy consumption. This thesis is a compilation of a number of studies done on magnetic refrigeration for room-temperature applications.In the first study, the environmental impacts associated to magnetic refrigeration are looked at closely through a life cycle assessment. The life cycle assessment indicates that because of the environmental burdens related to the rare-earth materials used in magnetic refrigeration, the reduction in the environmental impacts is not guaranteed by switching to magnetic refrigeration technology. Accordingly to avoid the extra environmental impacts the magnetic refrigeration systems should use magnetic materials frugally, which requires an optimized design. In addition, operation with higher efficiency compared to vapor-compression systems is necessary to have environmental advantages, at least in some impact categories.A practical method to optimize the design of magnetic refrigeration systems, e.g. to have a compact design or high efficiency, is utilizing a flexible software model, with which the effect of varying different parameters on the performance of the system can be simulated. Such a software model of the magnetic refrigeration system is developed and validated in this project. In developing the model one goal is to add to the precision of the simulated results by taking more details into consideration. This goal is achieved by an innovative way of modeling the parasitic heat transfer and including the effect of the presence of magnetocaloric materials on the strength of the field created by the magnet assembly. In addition, some efforts are made to modify or correct the existing correlations to include the effect of binding agents used in some active magnetic regenerators. Validation of the developed software model is done using the experimental results obtained from the prototype existing at the Department of Energy Technology, KTH Royal Institute of Technology.One of the parameters that can be modified by the developed software model is the choice of the magnetocaloric materials for each layer in a layered active magnetic regenerator. Utilizing the software model for optimizing the choice of the materials for the layers reveals that materials with critical temperatures equal to the cyclic average temperature of the layers in which they are used do not necessarily result in the desired optimum performance. In addition, for maximizing different outputs of the models, such as energy efficiency or temperature lift sustained at the two ends of the regenerators, different choice of materials for the layers are needed. Therefore, in other studies seeking to improve one of the outputs of a system, the choice of the transition or critical temperatures of the materials for each layer is an additional parameter to be optimized.The prototype existing at the Department of Energy Technology, KTH Royal Institute of Technology, was initially designed for replacing the vapor-compression system of a professional refrigerator. However, it could not fulfil the requirements for which it was initially designed. The aforementioned developed simulation model is used to see how much the choice of the materials, size of the particles, and number of layers can enhance the performance while the operation frequency and flow rate of the heat transfer fluid are at their optimum values. In other words, in that study the room for improvement in the performance without applying major changes in the system such as the geometry of the regenerator, which implies redesigning the whole magnet assembly, is investigated. In the redesign process the effect of binding agent and the limitations associated to different properties of it is also investigated theoretically. Nevertheless, the study did not show that with keeping the geometry of the regenerators and the currently existing magnetocaloric materials the initial goals of the prototype can be achieved.In the next study more flexible choice of geometries and magnetocaloric materials are considered. In fact, in this study it is investigated how much the magnetocaloric materials need to be improved so that magnetic refrigeration systems can compete with vapor-compression ones in terms of performance. For the two investigated cases, the magnetic-field dependent properties of the currently existing materials are enough provided that some other issues such as low mechanical stability and inhomogeneity of the properties are solved. Nevertheless, for more demanding design criteria, such as delivering large cooling capacity over a considerable temperature span while the magnetic materials are used sparingly, the magnetic-field dependent properties need to be enhanced, as well.A less explored area in room-temperature magnetic refrigeration is the subject of another study included in the thesis. In this study, solid-state magnetic refrigeration systems with Peltier elements as heat switches are modeled. Since the Peltier elements consume electricity to pump heat, the modeled systems can be considered hybrid magnetocaloric-Peltier cooling systems. For such systems the detailed transient behavior of the Peltier elements together with layers of magnetocaloric materials are modeled. The mathematical model is suitable for implementation in programing languages without the need for commercial modeling platforms. The parameters affecting the performance of the modeled system are numerous, and optimization of them requires a separate study. However, the preliminary attempts on optimizing the modeled system does not give promising results. Accordingly, focusing on passive heat switches can be more beneficial.
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| 5. |
- Aaboen, Lise, 1978
(author)
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Incubators and incubation -Resources and activities in relation to different actors
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- ABSTRACTIncubators prepare new technology-based firms (NTBFs) for the obstacles ahead, they complement and develop the entrepreneurial ability of the firm founder, advise regarding financing, as well as providing structure and credibility to the firm. Incubators accelerate the development of the firms towards growth, create an entrepreneurial and innovative climate in the region, and contribute to the commercialization of research results from the university. There are many descriptions but still there remains the difficulty of understanding what an incubator is, and what it does. There is a great difference between incubators due to them having been formed in relation to different actors who have varying histories. Based on the appended papers the principal actors in relation to incubators are: the incubator, the NTBFs, the university, the policy actors and the financial actors. Moreover, the part played by the incubator differs depending on the roles in relation to the different actors, and they often have more than one role in relation to the same actor. Hence, the purpose of this thesis is to explore incubation in relation to different actors. The exploration includes five appended papers. Three of the papers focus on the role of the incubators when helping the NTBFs find and utilize resources. The three types of resources are knowledge, financing and relationships. The two remaining papers focus on the incubator as an organization with particular interest in value creation and efficiency. All five appended papers are written using the resource-based view. In the cover paper the findings in the appended papers are reflected upon using the industrial network approach in order to provide another perspective, focusing on relationships as opportunities leading to an understanding of incubators and incubation. In the cover paper principal actors, activities and resources are explored. The NTBFs are developed through the incubation with the help of resources contributed by the other actors. Additional to the development, the cover paper discussed other activities included in the incubation, i.e. mediation, innovation and acceleration. These activities enable actors to access and combine resources, within and across firm boundaries, that they would otherwise have difficulties combining at that point in time, as quickly or in that way. The relationships of the incubator enable mediation of contacts between actors who are otherwise reluctant to collaborate. Through these collaborations new resource combinations may be found. Resource combinations in already existing relationship can be found using experience from other relationships. In other words, the relationships of the incubator contribute to innovation among the actors. Furthermore, the relationships of the incubator contribute to the acceleration of the NTBFs’ development by being a trusted third party actor, and by contributing to the coordination of actors aiming at improving the innovative climate. Hence, relationships are a special kind of resource for the incubators. The importance of the relationships for the incubators implies that the critical issues might not be to pick NTBFs based on criteria for growth potential, but rather on the ability to form and develop relationships for themselves, as well as the NTBF, in order to develop the firm. Furthermore, arguments regarding the increasing homogeneity among Swedish incubators are based on the rather formalized relationships with the policy actors where incubators tend to play rather similar roles. The heterogeneity is likely to be perceived as larger from the perspective of relationships that are more context specific. Moreover, the relationships, activities and combination of resources cross-fertilize each other without a natural or manageable direction that cannot be controlled by one or a few of the actors involved. After the concluding discussion there is a retrospection of the development of the thesis and the empirical material, which is based on qualitative and quantitative data that has been gathered within the Swedish incubator program mainly during 1999, 2005 and 2006.
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| 6. |
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| 7. |
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| 8. |
- Aagaard, Philip
(author)
-
Cardiovascular assessment in middle-aged male long distance runners
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Endurance events such as long distance running races are increasing in popularity and convey multiple health benefits. However, such exercise forms also represent a major challenge to human cardiovascular physiology and are associated with a momentarily increased risk for adverse cardiac events. Using the world’s largest cross-country running race Lidingöloppet as a model of endurance events, this thesis aims to: 1) investigate male and female participation and performance trends 2) detail the cardiovascular findings of a comprehensive cardiovascular preparticipation evaluation in novice male race participants aged 45 years and older 3) study the impact of race participation on cardiac autonomic tone and 4) assess features of cardiovascular function and vectorcardiography (VCG), and their response to endurance exercise in individuals with early repolarisation (ER). Study I: Participation and performance trends were investigated in >120,000 runners partaking in the Lidingöloppet between 1993 and 2007. In a subgroup of 249 middle-aged males, the association between the cardiac biomarker NT-proBNP and runtime was also studied. Participation increased over the study period, particularly in females and older males, while participants’ fitness deteriorated, as measured by an average increase in runtime of 21 ± 31 min. Longer runtimes were independently associated with higher levels of NT-proBNP. Study II: A preparticipation cardiovascular exam was performed in 153 middle-aged male first-time Lidingöloppet race participants. Runners were assessed by medical history and physical exam, 12-lead ECG, echocardiography, and blood tests. 9 % of runners required further diagnostic work-up and 2 % were discouraged from race participation due to cardiac abnormalities that could increase their risk of exercise- related cardiac events. Study III: Heart rate (HR) and heart rate variability (HRV) was continuously measured from 48 hours before until 96 hours after a Lidingöloppet 30km race. Compared to pre-race values, HR was elevated during the night after the race while HRV remained depressed for 64 [51 - 96] hours after the race. A reduced HR recovery and a greater fall in HRV post race were associated with higher levels of high-sensitivity troponin T (hsTnT). Study IV: The prevalence and associated cardiac features of ER, characterized by ST-segment elevation (STE) and/or J-waves, was investigated in 153 middle-aged males registered for first-time participation in the Lidingöloppet 10, 15 or 30km race. ER was present in 40 % and generally associated with features of better cardiovascular fitness. The cardiovascular effects of participating in the 30km race (n= 94) were also assessed after the race; runners with J-waves, but not with STE alone, showed changes of repolarisation parameters usually considered unfavourable (e.g. prolonged T peak-to-end (Tpe) and QTc). Conclusion: This thesis demonstrated that increased participation in a long distance running event (Lidingöloppet) was paralleled by deteriorating runtimes. In middle-aged men, longer runtimes were associated with higher levels of NT-proBNP. These findings may raise concern regarding the fitness and cardiovascular health of some of today’s race participants. A comprehensive preparticipation evaluation identified 9 % of first- time runners needing additional work-up and 2% who were ultimately discouraged from participating, suggesting that such a protocol is useful to identify individuals requiring further testing prior to vigorous exercise. After the race there was a prolonged depression of HRV. The magnitude and duration of HRV depression correlated with higher levels of hsTnT, suggesting that the degree of troponin (Tn) increase after strenuous exercise may reflect the level of exercise-induced cardiovascular stress. ER was generally associated with a benign cardiovascular profile, although subjects with J-waves showed post-race changes in some parameters of ventricular repolarisation that are usually associated with increased arrhythmia propensity. More research into the mechanisms and potential preventive measures of adverse exercise related effects on cardiac function is warranted.
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| 9. |
- Aagaard, Sunniva Margrethe Due
(author)
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Reticulate Evolution in Diphasiastrum (Lycopodiaceae)
- 2009
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Doctoral thesis (other academic/artistic)abstract
- In this thesis relationships and the occurrence of reticulate evolutionary events in the club moss genus Diphasiastrum are investigated. Diphasiastrum is initially established as a monophyletic group within Lycopodiaceae using non recombinant chloroplast sequence data. Support is obtained for eight distinct parental lineages in Diphasiastrum, and relationships among the putative parent taxa in the hypothesized hybrid complexes; D. alpinum, D. complanatum, D. digitatum, D. multispicatum, D. sitchense, D. tristachyum and D. veitchii are presented. Feulgen DNA image densitometry data and sequence data obtained from three nuclear regions, RPB2, LEAFY and LAMB4, were used to infer the origins of three different taxa confirmed to be allopolyploid; D. zanclophyllum from South Africa, D. wightianum from Malaysia and an undescribed taxon from China. The two Asian polyploids have originated from two different hybrid combinations, D. multispicatum x D. veitchii and D. tristachyum x D. veitchii. Diphasiastrum zanclophyllum originates from a cross between D. digitatum and an unidentified diploid taxon. The occurrence of three homoploid hybrid combinations commonly recognized in Europe, D. alpinum x D. complanatum, D. alpinum x D. tristachyum and D. complanatum x D. tristachyum, are verified using the same three nuclear regions. Two of the three hybrid combinations are also shown to have originated from reciprocal crosses. Admixture analyses performed on an extended, dataset similarly identified predominately F1 hybrids and backcrosses. The observations and common recognition of hybrid species in the included populations are hence most likely due to frequent observations of neohybrids in hybrid zones. Reticulate patterns are, however, prominent in the presented dataset. Hence future studies addressing evolutionary and ecological questions in Diphasiastrum should emphasize the impact of gene flow between parent lineages rather than speciation as the result of hybridization.
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| 10. |
- Aagerup, Ulf, 1969-
(author)
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It’s Not What You Sell : It’s Whom You Sell it To: How the Customer’s Character Shapes Brands and What Companies Do About it
- 2015
-
Doctoral thesis (other academic/artistic)abstract
- In this dissertation I investigate the effects of user and usage imagery on brands and how businesses employ user imagery to build brands. Over four articles I present results that suggest that user imagery affects brand personality and that companies under certain conditions adapt their behavior to optimize this effect. Although both mass market fashion and nightclubs are susceptible to the influence of user imagery, out of the two only nightclubs actively reject customers to improve its effect on brand perception. I relate these practices to the practical and financial feasibility of rejecting customers, the character of nightclubs’ brands, and to their inability to differentiate their brands through any other brand personality influencer besides user imagery. In this dissertation, I also discuss the ethical ramifications of user imagery optimization through customer rejection. In one study, the role of conspicuous usage imagery on socially desirable consumer behavior is investigated. It is concluded that conspicuousness increases consumers' propensity to choose environmentally friendly products, and that this tendency is especially pronounced for individuals that are high in attention to social comparison information. The conclusion is that consumers use green products to self-enhance for the purpose of fitting in with the group rather than to stand out from it.
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| 11. |
- Aalaei, Kataneh
(author)
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Processing and Storage stability of Skim Milk Powder : Monitoring Early and Advanced Stages of the Maillard Reaction
- 2017
-
Doctoral thesis (other academic/artistic)abstract
- The non-enzymatic browning known as the Maillard reaction has been the subject of extensive investigation for decades. Studies have focused on areas such as changes in flavour, colour, texture, and the nutritional properties of food materials as a result of this reaction. However, this complex reaction between the amino acids in proteins and reducing sugars in carbohydrates, is still not fully understood, especially the reaction mechanisms and potential impacts on health.Skim milk powder (SMP), is a multi-functional and extremely popular ingredient in the food industry, and is used in infant formulas, reconstituted and fermented dairy products, frozen desserts, bakery products, coffee whiteners, and even processed meat products. Despite the apparent good stability of SMP, it is prone to the Maillard reaction and its consequences, due to its composition, as well as the application of various kinds of thermal processing, and subsequent prolonged shelf life.The aims of this work were thus to improve our understanding of the occurrence of the Maillard reaction in SMP after the application of different drying techniques, and during subsequent storage under realistic conditions, in order to be able to predict and to control the reaction. Previous studies have mainly been conducted on model food systems at the conditions applicable to processing, i.e. at temperatures above 40 ºC. In the present work, changes in two indicators of the early and advanced stages of the Maillard reaction, namely the available lysine and carboxymethyl lysine (CML), respectively, were monitored during storage.To obtain a better understanding of the impact of processing on the progression of the reaction, three different drying techniques were studied and compared on pilot scale: freeze-drying, spray-drying and drum-drying. The extent of the reaction during prolonged storage for 200 days was studied, considering three storage variables: temperature, relative humidity (RH) and time.The kinetics of the available lysine in a commercial, industrially produced SMP was subsequently established over 30 days (the maximum recommended period for the consumption of opened packages) under conditions normally encountered during domestic storage. Furthermore, theearly and advanced stages of the reaction were studied in selected infant formulas available on the Swedish market.The results of these studies showed that the drying technique had a significant impact on the initiation of the Maillard reaction. Furthermore, the storage variables (temperature, RH and time) were also crucial factors in the gradual progression of the reaction during storage. The pattern of the decrease in the available lysine content during 200 days of storage was similar, regardless of the type of SMP. After storage at 52% RH and 30 ºC, a 39.2 – 45.9% decrease in the available lysine content was seen after 200 days. The corresponding value following storage at 52% RH and 20 ºC was 21.2 – 31.8%, indicating the importance of the storage temperature. Storage at 33% RH and 30 ºC caused a 5.2 – 22.4% decrease in the available lysine content, while no significant decrease in the available lysine content was seen after storage at 33% RH and 20 ºC, thus it was considered to be the ideal storage conditions for SMP.Studies of the advanced phase of the Maillard reaction using CML revealed that twice as much CML was formed in the spray-dried powders, than in the freeze-dried samples, after 200 days. The corresponding value in the drum-dried samples was 1.6 times that in the freeze-dried samples.The findings of this work have practical implications for SMP and SMP-based products in the food industry, and can be used to predict and control the Maillard reaction during storage, in order to ensure the safety of these products on the market.
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| 12. |
- Aalberg Haugen, Inger Marie, 1980-
(author)
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The diapause switch : Evolution of alternative developmental pathways in a butterfly
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Diapause decision is a classic example of a threshold switch mechanism with cascading effects on morphology, behaviour and life-history traits. This thesis addresses the downstream effects of the insect diapause switch, with the main focus on pathway-specific regulation of life-history traits, using the speckled wood butterfly (Pararge aegeria) as a study species. The ultimate pathway decision is made towards the end of larval development and allows the larvae to take into account up-to-date information from the environment about future conditions (Paper I, IV). However, already from an early point in development the larvae are sensitive to environmental cues and continuously adjust their growth trajectory in accordance to current information about the environmental conditions to be expected in future (Paper IV). An asymmetry in the ability to change from one developmental pathway to another at a late point in larval development suggests that the diapause and the direct pathway require different physiological preparations (Paper IV). Pathway-specific regulation of traits downstream of the diapause switch is maintained by ongoing selection. When the direct pathway is not regularly expressed, as with a shift from bivoltinism to univoltinism, relaxed selection on the unexpressed pathway leads to genetic drift and loss of protandry (Paper II, III). Natural populations display local adaptations in the diapause switch with an increase in critical daylengths as there is a gradual shift from bivoltinism to univoltinism (Paper III). This thesis highlights two aspects of the diapause decision, the determination of how and when this decision is made as well as the way the resulting pathways are moulded by selection in order to produce adaptive seasonal polyphenism in life-history traits.
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| 13. |
- Aalders, Johannes Theodor
(author)
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Ghostlines: Movements, Anticipations, and Drawings of the LAPSSET Development Corridor in Kenya
- 2020
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Doctoral thesis (other academic/artistic)abstract
- The Lamu Port-South Sudan-Ethiopia-Transport (LAPSSET) corridor is a partly completed development corridor in Kenya that will connect the eponymous places via roads, pipelines and railway lines, if completed. This thesis investigates how inhabitants of the traversed area navigate and shape the spatio-temporal landscape of the corridor, following three motifs: lines created through moving, anticipating, and drawing. Under moving, the thesis explores people’s encounters of LAPSSET as connection, obstacle, and repulsion, relying on mobile ethnography. In anticipating, the thesis introduces ‘spectral landscapes of anticipation’ to investigate different temporalities people create in relation to the corridor. In drawing, it considers ways of visualizing and envisioning infrastructure projects and introduces Collaborative Comic Creation as a possibility to cut through the visual normativity of infrastructural megaprojects.
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| 14. |
- Aalto, Aino-Maija
(author)
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Incentives and Inequalities in Family and Working Life
- 2018
-
Doctoral thesis (other academic/artistic)abstract
- Essay I: Same-gender teachers may affect educational preferences by acting as role models for their students. I study the importance of the gender composition of teachers in math and science during lower secondary school on the likelihood to continue in math-intensive tracks in the next levels of education. I use population wide register data from Sweden and control for family fixed effects to account for sorting into schools. According to my results, the gender gap in graduating with a math-intensive track in upper secondary school would decrease by 16 percent if the share of female math and science teachers would be changed from none to all at lower secondary school. The gap in math-related university degrees would decrease by 22 percent from the same treatment. The performance is not affected by the higher share of female science teachers, only the likelihood to choose science, suggesting that the effects arise because female teachers serve as role models for female students.
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| 15. |
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| 16. |
- Aalto, Susanne, 1964
(author)
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Molecular Clouds in Starburst Galaxies
- 1994
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Doctoral thesis (other academic/artistic)abstract
- Starbursts in the centres of galaxies are believed to be caused by funneling of gas towards the inner regions. Gravitational interactions between galaxies are known to cause vast rearrangements of their structure as well as induce bursts of star formation in their nuclear regions. However, radial gas-transport may also be the result of a bar- instability intrinsic to the system. This report deals with the effect of a starburst on the molecular medium of galaxies. The mm-wave, rotational transitions of interstellar molecules serve as probes of the physical conditions, kinematics and total mass of the molecular gas. Observations of the J=1-0, J=2-1 and J=3-2 transitions of 12Co, the J=1-0 and J=2-1 transitions of 13Co, the J=1-0 transitions of C180 and HCN and the J=2-1 transition of CS are used to determine the properties of the molecular gas in starbursting and normal galaxies. The mean escape probability approximation is used to solve the radiative transfer equations. The inferred properties of the molecular clouds in the centres of starburst galaxies differ from those of Galactic disk clouds. Such a deviation is likely to be induced by a central gas concentration and/or the nuclear starburst disrupting the clouds. Large 12CO/13CO J=1-0 intensity ratios (R>20) are measured towards luminous mergers implying unusual, high-pressure, molecular cloud ensembles. Model cloud ensembles for the merging system, NGC 3256, and the starburst spiral NGC 1808 suggest that the 12CO-emission is dominated by warm (Tk = 100 - 300 K), small (0.5-1 pc) and moderately dense (n = 2 - 7 x 103 cm-3) molecular clouds. Such temperatures and densities are typical of Galactic photon dominated regions (PDRs). Statistical studies of molecular line ratios towards galaxy centres indicate that the optical depth of the 12CO 1-0 emission is moderate, .tau.Ã? 1. Many starburst galaxies have large-scale excitation gradients indicating warm, dense gas in the centre, and normal cool molecular gas in their extended disks. NGC 3256, in particular, has a large R = 35 in the centre, while it is found to be only R = 10 - 15 at positions 43" off centre. The model cloud ensemble of NGC 1808 indicate that the 12CO-emitting gas may be diffuse rather than self-gravitating, this could be a common phenomenon in starburst galaxies.
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| 17. |
- Aaltonen, Emil
(author)
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Prokaryotic Arsenic Resistance - Studies in Bacillus subtilis
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Arsenic is a toxic metalloid which is found all over the globe. Due to its toxicity and wide abundance, all living organisms have evolved intrinsic arsenic resistance systems. In this study, three proteins that provide arsenic resistance in the Gram-positive bacterium Bacillus subtilis have been investigated. Acr3 is a trans-membrane protein that extrudes arsenite to the cell exterior. It belongs to the ACR family of arsenite transporters. Experimental data on the topology of Acr3, the first ever for a member of the ACR family, is provided and show that Acr3 has 10 trans-membrane helices. Both the N- and C-terminal ends of Acr3 are located to the cytoplasm and the protein has unusually short loops connecting its helices. ArsR is an arsenite sensitive transcription regulator that controls the expression of genes encoding arsenic resistance proteins. Experiments show that the operator site for ArsR from B. subtilis consists of a 6-6-6 inverted repeat and that DNA binding by ArsR involves formation of higher order multimers of the protein. The ArsK (former YqcK) protein has an unknown function. The present study shows that the arsK gene contributes to resistance towards both arsenite and arsenate. The results indicate that the function of ArsK is important in an aerobic environment and that it decreases the inhibitory effect that arsenite has on the sporulation efficiency of B. subtilis. A function of ArsK that involves an enzymatic addition of low molecular weight thiols to arsenic is proposed.
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| 18. |
- Aaltonen, H Laura
(author)
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Measuring distal airspace dimensions with nanoparticles. Initial development of a diagnostic method.
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Chronic obstructive pulmonary disease (COPD) consists of emphysema and bronchial disease. The pulmonary function tests currently used to diagnose COPD have poor sensitivity for early disease. This may delay diagnosis and lead to a poorer prognosis compared to establishing the diagnosis at an earlier stage.The aim of this thesis was to investigate a new nanoparticle-based method, termed Airspace Dimension Assessment (AiDA), to chart distal airspace morphology, and to examine the technique as a possible diagnostic biomarker foremphysema. In AiDA, inhaled nanoparticles’ deposition behavior is utilized to characterize distal airspace properties.Nanoparticles, as opposed to larger particles, are able to penetrate into the distal lung, where they deposit almost exclusively by diffusion. The particles’ likelihood to deposit is dependent on the diffusion distance. The thesis isbased on the hypothesis that in persons with enlarged, emphysematous airspaces, fewer particles will deposit, as opposed to healthy persons with narrower airspaces.In paper I, significant nanoparticle deposition differences between 19 COPD-patients with mainly moderate-to advanced emphysema and 19 healthy controls were found. The deposition correlated to disease severity as measured by computed tomography (CT) densitometry and diffusion capacity for carbon monoxide (DL,CO). In paper II, nanoparticle deposition was used to calculate distal airspace radius in 19 healthy volunteers. The radius correlated to lung density as measured by magnetic resonance imaging (MRI). In paper III, the average radius in 403 individuals without previous pulmonary disease or respiratory symptoms was found to be 293 ± 36 μm. The radius and its variation in population was found to be approximately comparative to other methods. It was noted that the radius was on average 13 μm larger in male ever-smokers compared to never-smokers, which may reflect early smoking-related changes. In paper IV, we concluded that in a population sample of 618 individuals, the persons with computed tomography evidence of emphysema (N = 47) had significantly larger distal airspace radii compared to persons without emphysema. We also showed that comorbidities did not significantly affect the results.In conclusion, we suggest the AiDA radius is a promising biomarker candidate for emphysema. Further validating studies, including a diagnostic study in a population seeking health care attention with symptoms and historyindicative of COPD, are warranted.
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| 19. |
- Aaltonen, Jaana, 1969-
(author)
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Ground Monitoring using Resistivity Measurements in Glaciated Terrains
- 2001
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Doctoral thesis (other academic/artistic)abstract
- The most common method of monitoring and mapping groundwatercontaminants is to extract and analyse a number of groundwatersamples from wells in the investigation area. However, thereare a number of limitations with this type of point-wiseinvestigation, as it is hard to acquire an adequate picture ofa heterogeneous and anisotropic subsurface using a fewpoints. To overcome the limitations of point investigations and toimprove ground monitoring investigations in a cost-effectiveway, support can be provided by direct current resistivitymeasurements, which give a characterisation of the electricalproperties of a ground volume. The main objective with this work was to investigate theusability of the resistivity method as a support in monitoringgroundwater contaminants in glaciated terrains and underdifferent seasons, both in long-term monitoring programmes andintracer tests. The work comprised field investigations at several differentsanitary landfills and four tracer tests in differentgeological environments, around the Stockholm region. The maininvestigations have been done at Högbytorp, Stockholmwhich has been used for long-term investigations of theresistivity variation, together with a field set up formonitoring and measurements on seasonal variation in soilmoisture, ground temperature and precipitation. It can be concluded that the use of resistivity measurementssupplies valuable information in the case of mapping andmonitoring conductive groundwater contaminants andfurthermore: The variation in resistivity (in shallow investigations<1 m) can be extensive between different seasons (around30 % compared to a mean value in till and clay soils) andshould be considered, so that anthropogenic affects can beseparated from natural resistivity variation. For deeperinvestigations (>5 m) the seasonal resistivity variationwas more moderate (around 15% compared to a mean value intill and clay soils). Soil moisture variation shows a strong relationship toresistivity variation in the investigated clay and tillsoils. Together with temperature correction 47 to 65% of thevariation has been explained. Three types of monitoring systems can be applied:Permanently installed, partly installed and fully mobilesystems. For the actual measurements, all three types can useeither high-density techniques such as CVES (ContinuousVertical Electrical Sounding) or low-density measuring withone or some different electrode spacings. The suggested evaluation tool for monitoring programmesshowed that it was possible to detect a decrease of 15 % inthe mean value at a specific site using Modified Double Masscalculations between resistivity time series and time seriesat a reference site with a comparable seasonalvariation. Resistivity measurements may be used as a valuablecomplement to groundwater sampling in tracer tests. Adecrease in resistivity, a minimum and a recovery phasereflect the passage of a NaCl-solution, which can be used toestimate flow velocity and flow patterns of the investigatedaquifer. The achieved recovery of NaCl in the tracer testscarried out was estimated to 20 to 70 %. The measurement system for long-term monitoring or tracertests, which should be chosen with regard to layout andfrequency, depends on the purpose of measurement and onsite-specific conditions and therefore no standard solutioncan be proposed. Key words:Resistivity, Direct Current, Monitoring,Groundwater, Contaminant, Tracer test, Geophysics.
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| 20. |
- Aaltonen, Kristina
(author)
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Mating system evolution and self-incompatibility in the wild plant species Brassica cretica
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Compared to animals like ourselves, plants have a very flexible sexual life. Most plants are, for example, hermaphrodites with the potential capacity for reproduction by self-fertilization (or selfing). While selfing can provide several definite advantages for the individual plant, there is a downside; mainly the severe reduction in fitness due to inbreeding depression. To avoid the negative consequences of selfing, many hermaphrodite plant species have evolved an intricate self-recognition – or self-incompatibility (SI) – system that prevents fertilization by cognate pollen. SI is in the majority of cases genetically controlled by a narrowly delimited region of the genome, called the S locus. The S locus contains several tightly linked genes, two of which – SRK and SCR – determine the pistil (female) and pollen (male) SI recognition type. One of the best-characterized SI systems is found in the Brassicaceae family, which includes the model plant Arabidopsis thaliana and a number of economically important crop species of the Brassica genus, e.g. rape seed, cabbage, and turnip. For evolutionary biologists, SI have long been a prominent and fascinating example of Darwinian natural selection acting in a frequency-dependent manner, i.e. the rarer a genetic variant becomes, the more favoured by natural selection it is. For the S locus, this means that a very large number of variants – or haplotypes – are expected to be maintained in a population and that the DNA sequences of different haplotypes will be very divergent. However, until recently there has been a shortage of empirical studies from natural plant populations to test these, and other, theoretical predictions of S locus evolutionary dynamics. In this thesis, I have produced the largest SRK and SCR DNA sequence data set from a wild Brassica species available to date. These data have allowed me to explore, in more detail than previously possible, the population genetic properties and the evolutionary history of the Brassica S locus. Moreover, accompanying studies of the pattern of inheritance of S locus variants and the occurrence of self-fertilization in natural B. cretica population have added novel information of great value to the understanding of how plants produce offspring in nature.
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| 21. |
- Aanesen, Arthur
(author)
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GABA and human spermatozoa : characterization and regulation of GABA transport proteins
- 1998
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Doctoral thesis (other academic/artistic)abstract
- The present project aimed at investigating the interaction between GABA and human spermatozoa under in vitro conditions. Our initial hypothesis was that human spermatozoa had specific binding proteins for GABA and that the binding of GABA to such binding sites could affect sperm function. Studies on swim-up preparations of human spermatozoa incubated with radiolabelled GABA in the presence of unlabelled GABA, alternatively displacers of GABAA/B receptors and GABA transport proteins, indicated that GABA specific binding sites were present on the surface of human spermatozoa. The potency of the different inhibitors indicated that the binding sites possibly represented GABA transport proteins. No effect on sperm motility or AR was observed following incubation with GABA. Further studies indicated that human spermatozoa are capable of a carrier mediated GABA uptake. The uptake is dependent on the concentration of chloride and sodium in the external medium, and the kinetic properties of the carrier resembled high affinity GABA transport proteins. Uptake of radiolabelled GABA into human spermatozoa in the presence of steroids was investigated. We examined progesterone, other steroids known to increase calcium influx, and steroids known to be ineffective as stimulators of calcium influx in human sperm. The results demonstrated a twofold increase in GABA uptake following preincubation with P or steroids known to stimulate calcium influx. In contrast, an inhibition of GABA uptake following preincubation with activators of protein kinase C was observed. The results suggest a role for PKC in the regulation of GABA transport in human spermatozoa. The reduced GABA uptake following incubation with phorbol esters and diacyl glycerol (DAG) analogues, as well as the lack of effect observed following addition of inactive DAG analogues, strongly indicate such a regulatory pathway. The existence of GABA transporter m-RNA and proteins in human testis and sperm was examined using RT-PCR, immunohistochemistry and immunoblotting. Oligonucleotide primer pairs were designed from nucleotide sequences for the three cloned GABA transport proteins identified in human brain: GAT-1, GAT-3 and BGT-1. From homogenized human testis, PCR products of predicted size and with homology to respective GABA transport proteins were identified. This finding indicates the MRNA expression of all three GABA transporters in human testicular tissue. Studies on the protein expression of GABA transporters in sperm cells were performed with SDS-PAGE and immunoblotting techniques. Immunoblots using polyclonal antibodies raised against rat GAT-1, GAT-2 and GAT-3 recognized bands of approximately 65kDa, indicating cross-reactivity to GABA transporters present in human sperm cells. Pharmacological characterization of GABA uptake with specific inhibitors of GABA transport revealed a unique sequence in the relative potencies of the inhibitors tested. The results may indicate the presence of more than one GABA transporter in the plasma membrane of human spermatozoa. Immunoblots and immunohistochemistry studies indicate the presence of one or several GABA transporters in human spermatozoa and testis, these results are supported by pharmacological studies using specific inhibitors of GABA transport. These studies add new information to the present knowledge concerning GABA and human spermatozoa. They also for the first time describe specific GABA transport proteins in the male reproductive tract. Further studies are however, required to elucidate the functional role for these proteins in terms of human reproduction.
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| 22. |
- Aanestad, Øystein
(author)
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Quantitative electromyographic studies of the perineal muscles in normal subjects and patients suffering from anal or urinary incontinence
- 1998
-
Doctoral thesis (other academic/artistic)abstract
- The aims of the study were to characterize the interference pattern in perineal muscles in healthy subjects with the use of quantitative EMG techniques, to evaluate if prostatic surgery had any effect on the interference pattern and furthermore to examine the interference pattern in the perineal muscles in patients suffering from urinary or anal incontinence.The interference pattern in the perineal muscles was examined with a computerized analysis, the Turns and Amplitude (T/A) analysis, and the innervation pattern of the muscles was examined with single fiber electromyography measuring the fiber density. Reference values were collected from 30 normal subjects. The patient material consisted of 20 males subjected to transurethral prostatectomy (TUR-P), 10 males who underwent radical retropubic prostatectomy (RRP), 20 patients suffering from anal incontinence and 24 women withurinary incontinence.T/A analysis of the interference pattern in the perineal muscles in normal subjects showed a significant increase in number of turns/sec and mean amplitude correlating to increasing force but no age-related changes.TUR-P and RRP did effect the innervation of the distal urethral sphincter muscle as shown by increased fiber density indicating a peripheral nerve lesion. T/A analysis did not shown any increased activation of the distal urethral sphincter as a compensation for the loss in bladder neck sphincter function but rather signs of decreasedcentral activation.Patients with idiopathic faecal incontinence showed signs of impaired innervation of the external anal sphincter muscle. A decreased interference pattern at maximal contraction indicated a reduced central activation of perineal muscles, in particular for patients with partial rupture of the external anal sphincter muscle. The reduced central activation could play a role for the aetiology of faecal incontinence.Patients with urinary stress incontinence also showed signs of impaired innervation of the external anal sphincter muscle as well as reduced interference pattern at maximal contraction and during continuous recording of the EMG activity during cystometry. A reduced central activation of the motor units was predicted as one factor involved in the aetiology.
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| 23. |
- Aardal-Eriksson, Elisabeth
(author)
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Salivary cortisol and posttraumatic stress reactions : methodological and applied studies before and after trauma
- 2002
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Doctoral thesis (other academic/artistic)abstract
- The field of psychotraumatology has its roots in ancient history. During the past decades, the surveillance of the psychobiological background of reactions to and consequences of traumatic stress has made great progress and the complexity of the human stress response system stands out. The hypothalamic-pituitary-adrenocortical axis activity, modulated by various neuroimmunological substances, seems to play a major role in the stress response. However, there are still inconsistencies in explanations of relationships between biological and psychological changes following traumatic stress. Moreover, the matter of predictive factors for the development of posttraumatic morbidity is still in a speculative phase.The aims of the present thesis were to further develop a commercial serum cortisol radioimmunoassay (RIA) for determination of cortisol in saliva and to test its reliability, specificity and sensitivity as a biochemical assay. The saliva sampling procedures and sample storage stability were also to be tested. Further issues were to investigate determinations of salivary cortisol and serum prolactin in relation to selfratings of posttraumatic psychological distress and general psychological health. Possible predictive and concurrent validity of salivary cortisol as a biochemical marker for posttraumatic psychological distress were to be tested.Cortisol is present in saliva mainly in non-protein form, representing the free, biologically active fraction of the total plasma cortisol concentration. In a first phase of the present thesis, the commercial serum cortisol RIA was modified for determination of cortisol in saliva. The relation between salivary and serum cortisol concentrations was tested. Reference ranges at 8 AM and 10 PM for the salivary cortisol assay were established from 195 healthy subjects. Salivary cortisol concentrations were tested in relation to serum cortisol in estimating adrenocortical function during endocrine dynamic function tests in 37 patients and 13 healthy controls. In testing salivary cortisol as a marker for stress for fieldwork use, a screening study was performed on 66 male rescue workers. Salivary cortisol at 8 AM and 10 PM and serum prolactin were determined and general psychological health and posttraumatic psychological distress were estimated with the self-rating scales General Health Questionnaire, Impact of Event Scale and Posttraumatic Symptom Scale. These scales were used in the second phase of the thesis. Three applied follow-up studies were performed with sampling of salivary cortisol and self-ratings: (a) a study of 31 UN-soldiers five days, two and nine months after a mine accident; (b) a study of 145 UN-soldiers before, at return, and two and six month after a six month mission. (c) a study of 101 UN-soldiers six and twelve months after a six month mission with severe combat exposure.The results from the present thesis indicate that the modified method of salivary cortisol determination possesses sufficient precision, accuracy, sample storage stability and procedural advantages for laboratory, clinical and field application. Moreover, it possesses moderate predictive information and moderate to high concurrent validity as a biochemical marker for posttraumatic psychological distress.
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| 24. |
- Aardal Lönnerfors, Celine
(author)
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Robot-assisted laparoscopy for benign uterine disease. Feasibility, outcome and hospital cost.
- 2015
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Doctoral thesis (other academic/artistic)abstract
- The introduction of the laparoscope was a milestone within gynecologic surgery. Despite evidence of better perioperative outcome compared to laparotomy, laparoscopy is mostly performed for less advanced surgical procedures and the uptake of laparoscopic hysterectomy has been slow. An effort to preserve the clinical benefits of laparoscopic surgery and facilitate the performance of more advanced surgery has led to the development of robot-assisted laparoscopic surgery. Technical progress has been advantageous for the patient from a historical point of view, but this cannot be assumed without proper evaluation. As for all surgical approaches, it is important to recognize the possible applications of robotic surgery as well as proper patient selection both from a clinical and economical point of view. The overall aim of this thesis was to investigate the possible applications, clinical outcome and hospital cost of robot-assisted laparoscopic surgery for benign uterine disease at a single institution following the introduction of robotic surgery. Study I: Evaluating the first 1000 robotic surgeries performed showed that a surgical robot provides the possibility to offer minimally invasive surgery to a larger patient population with low rates of conversions and intraoperative complications. Study II: 31 women with symptomatic, deep intramural myomas and either otherwise unexplained infertility or myomas with a possible effect on conception had a pregnancy rate following robotic myomectomy of 68%. Study III: All women (n=114) with a BMI ≥ 30 kg/m2 who underwent a simple hysterectomy by robotics or laparotomy during the study period were included. Robot-assisted laparoscopic hysterectomy in obese women was associated with shorter hospital stay, less bleeding, and fewer complications and longer operative time compared to laparotomy although the operative times for morbidly obese women were similar between robotics and laparotomy. Study IV: 122 women planned for minimally invasive hysterectomy for benign disease were randomly allocated to either robot-assisted- or traditional, minimally invasive hysterectomy in a 1:1 proportion with vaginal hysterectomy as a primary choice in the latter. From the perspective of hospital costs, robotic-assisted hysterectomy is not advantageous for treating non-complex benign conditions when a vaginal approach is feasible in a high proportion of patients. A similar hospital cost is attainable for laparoscopy and robotics when the robot is a preexisting investment. Study V: Complication rates in 949 women planned for robotic hysterectomy for malignant (75%) and benign (25%) gynecological disease over an 8-year period with special awareness of complications possibly related to robot specific risk factors. Intraoperative- and postoperative complications and complications possibly related to the robotic approach diminish with training, experience and refinement of practice. Study VI: All women (n=483) undergoing hysterectomy for benign disease during 2013 and 2014. Vaginal hysterectomy was associated with the lowest hospital cost and robotic hysterectomy with the lowest rate of perioperative complications. Procedure-specific proficiency influences outcome. Robotic hysterectomy for benign disease is clinically advantageous and economically feasible in complex cases, when performed by high volume surgeons.
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| 25. |
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