| 1. |
- Sandell, Mikael
(författare)
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Minimally Invasive Catheter-Based Technologies
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A simple incision procedure in a blood vessel makes the entire vascular system accessible. Through contrast injection and X-ray visualization, the vascular tree can be mapped and navigated through manual manipulation of thin tubes and wires. This utilization of the vasculature as internal pathways is commonly referred to as the endovascular technique. This technique can be used to deliver implants and drugs, retrieve problematic lesions or objects from the vasculature, or take tissue samples. Compared to open surgery, the advantage of this technique lies in the reduced invasiveness, ideally only leaving a small incision scar at the point of entry. Some interventions, however, are still associated with certain risks, requiring medication or complicating further interventions. The development of sequencing technologies presents an opportunity to improve and miniaturize devices, reducing invasiveness. This thesis aims to mitigate these risks and capitalize on the potential of next generation sequencing through microfabrication technologies, producing devices that are less invasive than current methods or that enable a new procedure.Initially, the aspect of endovascular heart biopsy is covered. The first work presents the fabrication and in vivo evaluation of a nitinol-based catheter device designed for extracting myocardial tissue. The device is fabricated through picosecond laser machining of nitinol tubes and wires, producing a device that is substantially smaller than what is currently used. The samples are evaluated and compared to samples extracted with conventional devices through RNA-Sequencing, verifying the proof of concept. The second work further emphasizes the device's functionality by evaluating it in a disease model of endomyocardial infarction. Tissue that is affected by the infarct and surrounding healthy tissue is extracted and compared in terms of its genetic expression. This comparison reveals a genetic discrepancy between the sick and healthy tissue, verifying the potential of using the device with RNA-sequencing for diagnostic purposes. The third work evaluates the safety aspects of the novel device in a head-to-head comparison with a conventional device. The study reveals a clear benefit of using the smaller device in terms of the complication rate during the procedure.The fourth work presents the fabrication and in vivo evaluation of another nitinol based catheter device designed for endothelial cell sampling. The device is fabricated through two-photon polymerization technologies, producing sub-mm brush structures mounted on a nitinol wire. Currently, there are no devices in clinical use that are capable of exclusively extracting endothelial cells. The novel device presents a solution for selective interaction with the innermost layer of the blood vessel. It represents an important step toward sampling endothelial cells for diagnostic and research purposes.The fifth and sixth works collectively present two different aspects of a third nitinol based catheter device designed to sample tissue from soft organs anywhere in the body. The device is fabricated using laser micromachining, grinding, and two-photon polymerization. The work is separated in terms of the in vivo evaluation and the technical solution. The technical aspects of the device are examined in terms of force generation in miniaturized catheter systems and the problems that arise in terms of mechanical scaling. These problems are solved by attaching pistons along the wire surface coupled with applied pressure to increase the force generated. The sampling with this device is realized, similar to the fourth work, with sub-mm brushes mountedon the wire. In vivo evaluation of this device reveals successful sampling of minute tissue quantities from the liver and kidney, in the size range of 10-100 cells per sample.The seventh work presents the in vivo and in vitro performance of a nanostructure coating on nitinol-based stents. Patients with a stent implant are prescribed an extensive medication regimen to counteract the metal implant's effects on the blood and surrounding tissue. This issue is being continuously targeted by new stent platforms, either with a drug-eluting polymer layer or by being resorbable by the body or through various other means. These implants all have a transient behavior, resulting in different issues over time. Paper VII presents an alternative approach to this problem by instead applying a nanostructure coating that is designed to interact with the blood to a much lesser degree, as demonstrated by CT-angiography and the measurement of multiple biomarkers.
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| 2. |
- Byström, Roberth, 1971-
(författare)
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SOD1´s Law : An Investigation of ALS Provoking Properties in SOD1
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Proteins are the most important molecules in the cell since they take care of most of the biological functions which resemble life. To ensure that everything is working properly the cell has a rigorous control system to monitor the proper function of its proteins and sends old or dysfunctional proteins for degradation. Unfortunately, this system sometimes fails and the once so vital proteins start to misbehave or to accumulate and in the worst case scenario these undesired processes cause the death of their host. One example is Amyotrophic Lateral Sclerosis (ALS); a progressive and always fatal neurodegenerative disorder that is proposed to derive from accumulation of aberrant proteins. Over 140 mutations in the human gene encoding the cytosolic homodimeric enzyme Cu/Zn-Superoxide Dismutase (SOD1) are linked to ALS. The key event in SOD1 associated ALS seems to be the pathological formation of toxic protein aggregates as a result of initially unfolded or partly structured SOD1-mutants. Here, we have compared the folding behaviour of a set of ALS associated SOD1 mutants. Based on our findings we propose that SOD1 mediated ALS can be triggered by a decrease in protein stability but also by mutations which reduce the net charge of the protein. Both findings are in good agreement with the hypothesis for protein aggregation. SOD1 has also been found to be able to interact with mitochondrial membranes and SOD1 inclusions have been detected in the inter-membrane space of mitochondria originating from the spinal cord. The obvious question then arose; does the misfolding and aggregation of SOD1 involve erroneous interactions with membranes? Here, we could show that there is an electrostatically driven interaction between the reduced apo SOD1 protein including ALS associated SOD1-mutants and charged lipid membrane surfaces. This association process changes the secondary structures of these mutants in a way quite different from the situation found in membrane free aqueous environment. However, the result show that mutants interact with charged lipid vesicles to lesser extent than wildtype SOD1. This opposes the correlation between decreased SOD1 stability and disease progression. We therefore suggest that the observed interaction is not a primary cause in the ALS mechanism.
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| 3. |
- Katz Thor, Rebecka, 1982-
(författare)
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Beyond the Witness : Holocaust Representations and the Testimony of Images
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In a time when the very last Holocaust witnesses will soon be gone, a possible route for commemoration is to ask what testimony images can give. This book seeks to answer the question of how images can bear witness by examining them as multifaceted entities produced, reproduced, and resituated in conflicting political and historical situations. In three archive-based films by Harun Farocki, Yael Hersonski, and Eyal Sivan, the moving image is reactivated and reinterpreted. Footage produced as internal Nazi propaganda and the video recordings of a politically charged trial in the aftermath of the Holocaust have accrued new meaning. The archival status, context, and conditions for production, and the means of representation, offer a framework for an analysis through which the testimony of images can be understood.
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| 4. |
- Zhang, Qing
(författare)
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Mechanical properties of semi-solid Al castings : Role of stirring
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aluminum castings have been widely used in the automotive industry to reduce the vehicle's weight. However, the existence of casting defects significantly limits its application. The most common and detrimental defects in aluminum castings are porosity and oxides. The formation of the pores comes from the solute hydrogen and volumetric reduction during the solidification process, resulting in the gas and shrinkage pores, respectively. The oxides can be introduced by either the operation during the process or the originally existing oxides in the melt. To reduce these defects, optimizing the casting process and controlling the melt quality is essential.In this work, the Semisolid Metal (SSM) process was used as it can significantly reduce the formation of shrinkage pores. The main focuses were on the influence of stirring intensity on the formation of casting defects and, thus, the resultant mechanical properties. In addition, to control the original melt quality, particularly the amount of oxides, efforts were made to develop proper methods for the melt quality assessment.The results show that the slurry-making process, mainly through stirring intensity, can affect the casting defects significantly. On the one hand, the increasing stirring intensity can distribute the primary Al particles more homogeneously, reducing the pores in terms of size and number by increasing the permeability during the solidification process. On the other hand, the increasing stirring intensity can affect the size of oxides differently, depending on the composition, for instance, the Mg content.For the alloys with sufficient Mg, the oxides would be MgAl2O4, which are small films with numerous cracks. Under intensive stirring, the oxides can break down into small oxide particles. As a result, intensive stirring can improve ductility by reducing the formation of big pores. However, the oxides would mainly be Al2O3 films for alloys with low Mg content. In this case, the current stirring intensity is insufficient to break the oxide films. Instead, the increased stirring has introduced more oxide films into the melt. Consequently, in the casting with intensive stirring, the increasing oxide films dominated the ductility rather than the reduced porosity.The SSM castings exhibit better bending fatigue properties than the casting using the traditional high-pressure die casting (HPDC) process. This improvement is mainly due to the formation of the harder surface liquid segregation (SLS) layer on the SSM casting surface. Furthermore, compared with the standard SSM process, the castings using intensive stirring (hereinafter referred to as the modified SSM process) show similar but more reliable fatigue properties. This reliable fatigue property can be attributed to eliminating the big internal pores through intensive stirring, which results in local stress concentration and significantly reduces fatigue performance. Besides, due to the gradient stress distribution in the bending loading, the surface defects play a significant role in the fatigue properties. With the increase of the specimens’ thickness, the failure mechanisms changed.The shrinkage pores in the reduced pressure test (RPT) test play a significant role in the accuracy of melt quality assessment. A good correlation between the bifilm index (BI)/ density index (DI) and hydrogen content is observed for the RPT samples without significant shrinkage pores. In addition, the correlation between the BI and elongation is also strongly affected by the clusters of shrinkage pores due to the conflict between the definition of the BI and the influence of clusters of shrinkage pores on the ductility. Based on this, we proposed an optimized BI where the clusters of shrinkage pores were treated as single pores, increasing the reliability of the correlation between the BI and elongation.
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| 5. |
- Ekström, Madeleine, 1984-
(författare)
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Oxidation and corrosion fatigue aspects of cast exhaust manifolds
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Emission regulations for heavy-duty diesel engines are becoming increasingly restrictive to limit the environmental impacts of exhaust gases and particles. Increasing the specific power output of diesel engines would improve fuel efficiency and greatly reduce emissions, but these changes could lead to increased exhaust gas temperature, increasing demands on the exhaust manifold material. This is currently the ferritic ductile cast iron alloy SiMo51, containing about 4 wt% Si and ~1 wt% Mo, which operates close to its fatigue and oxidation resistance limits at peak temperature (750C). To ensure high durability at higher temperatures, three different approaches to improving the life of exhaust manifolds were developed in this thesis.The first approach was to modify SiMo51 by adding different combinations of Cr and Ni to improve its high-temperature strength and oxidation resistance, or by applying a thermal barrier coating (TBC) to reduce the material temperature and thereby improve fatigue life. In the second approach, new materials for engine components, e.g. austenitic ductile iron and cast stainless steel, were investigated for their high-temperature fatigue and oxidation properties. In order to identify the most suitable alloys for this application, in the third the environmental effects of the corrosive diesel exhaust gas on the fatigue life of SiMo51 were investigated.The high-temperature oxidation resistance of SiMo51 at 700 and 800C in air was found to be improved by adding Cr, whereas Ni showed adverse effects. The effects of solid-solution hardening from Ni and precipitation hardening from Cr were low at 700C, with improvements only at lower temperatures. Applying a TBC system, providing thermal protection from a ceramic topcoat and oxidation protection from a metallic bond coat, resulted in only small reductions in material temperature, but according to finite element calculations still effectively improved the fatigue life of a turbo manifold. Possible alternative materials to SiMo51 identified were austenitic cast ductile iron Ni-resistant D5S and austenitic cast stainless steel HK30, which provided high durability of exhaust manifolds up to 800 and 900C, respectively. Corrosion fatigue testing of SiMo51 at 700C in diesel exhaust gas demonstrated that the corrosive gas reduced fatigue life by 30-50% compared with air and by 60-75% compared with an inert environment. The reduced fatigue life was associated with a mechanism whereby the crack tip oxidized, followed by crack growth. Thus another potential benefit of TBC systems is that the bond coat may reduce oxidation interactions and further improve fatigue life.These results can be used for selecting materials for exhaust applications. They also reveal many new research questions for future studies. Combining the different approaches of alloy modification, new material testing and improving the performance using coatings widened the scope of how component life in exhaust manifolds can be improved. Moreover, the findings on environmental interactions on SiMo51 fatigue provide a completely new understanding of these processes in ductile irons, important knowledge when designing components exposed to corrosive environments. The novel facility developed for high-temperature corrosion fatigue testing can be useful to other researchers working in this field.
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| 6. |
- Foultier, Christophe, 1972-
(författare)
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Regimes of Hospitality : Urban Citizenship between Participation and Securitization – the Case of the Multiethnic French Banlieue
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis analyzes various local development policies in Europe’s big urban areas. Striving to understand the respective places accorded to the measures to increase the participation of the inhabitants on the one hand, and to improve for security and public peace in the context of social and territorial policies on the other, I examine how urban policies define models of urban citizenship. The empirical work concerns two sites in the greater metropolitan area of Paris, Le Franc-Moisin–Bel-Air in Saint-Denis and Les Cinq Quartiers in Les Mureaux. It consists of an analysis of public documents as well as a series of interviews and observations. This methodological approach serves to gain an understanding of how participative and security procedures emerge in the history of French urban policy and how these norms interact locally.By investigating the overlap of security politics and participatory devices, I demonstrate that deprived areas do not have access to an adequate form of intervention to meet the expectations and needs of its inhabitants, who are squeezed between a logic of development reluctantly accepted by, but rarely negotiated with its inhabitants, and a logic of security that often leads to the confinement of residents to their respective areas. The thesis thus demonstrates how institutional interventions in multiethnic areas can fuel feelings of suspicion be-tween local stakeholders and civic distrust. Indeed, the participatory procedures that are developed in urban strategies influence the conduct of participants on matters of identity and belonging and can intensify socio-ethnic stigmatization. This effect provides me with a critical standpoint on new techniques of government. The local partners of the state develop daily routines in urban strategies that contribute to articulating participatory devices and security procedures. I claim that the results from this process are “regimes of hospitality”.
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| 7. |
- Grafström, Maria, 1978-
(författare)
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The Development of Swedish Business Journalism : Historical Roots of an Organisational Field
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Contemporary Swedish business journalism is an established organisational field with shared practice within and across organisations. Using a historical perspective, this dissertation investigates the early formation of this field and the formation of a shared meaning system for business journalism. Addressing the question of how and why the field emerged, the study contributes to institutional approaches in organisational analysis and theories about field development. Drawing on a qualitative longitudinal study, the analysis explores the source of today’s field of business journalism and examines the individuals, organisations, and activities that, during the 1960s and 1970s, laid the groundwork for subsequent field development. Five Swedish newspaper organisations are examined in detail: two business weeklies, Affärsvärlden and Veckans Affärer; the business daily, Dagens industri; and two general dailies, Dagens Nyheter and Svenska Dagbladet. In particular, the study analyses the competencies that was considered necessary for producing business news; the models that functioned as positive examples for business journalists; and the accepted ways of selecting and presenting business news. The study concludes that nascent field formation developed through institutional entrepreneurial processes in the interplay among individuals, organisations, and societal developments. As individuals carried institutional logics from their previous affiliations in business or journalism, they contributed to the nascent field formation – not by breaking with their past, but by continuing, in a new setting, previous ways of approaching their work. The two institutional logics of business and journalism also permeated the newspaper organisations in which these individuals were active. The organisations functioned as platforms that enabled the early practice while setting boundaries for its development. The results suggest that fields develop incrementally and that institutional entrepreneurial processes embody greater continuity and stability than previous research in the area has suggested.
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| 8. |
- Guyard, Carina
(författare)
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Kommunikationsarbete på distans
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This research thesis analyzes the characteristics of communication work in a call centre, by examining the communication work at a Swedish call centre which is outsourced to Latvia. The thesis studies the ways in which communication with the customers is organized, carried out and assigned meaning. Theoretically, the thesis draws on both critical and management-oriented perspectives of work. The empirical investigation combines participant observations at the call centre with individual interviews, mainly conducted with operators and management staff.The communication work is analyzed both as labour and as communicative activity. The concept of labour focuses upon the relation between employer and employee. Therefore, the analysis is placed within the framework of a capitalistic production system, through a survey of the economic and the organisational working conditions. The communicative activity deals with how the telephone conversations with the customers are enacted. In that part of the analyses, the working routines and the meaning making practices are illuminated.As examined in the current research, the communication work is indeed constructed in an alienated manner, through high levels of standardization, immobility, and estrangement from both customers and the customers’ culture. Nonetheless, merely being employed has meant significant economic security for the operators of the Latvian call centre. The operators are incumbents of a society affected by deep economic crises with high unemployment rates. In relation to their broader society, the employees have found meaning within their immediate social situation. This may explain why they endure the monotonous work with few opportunities for development.
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| 9. |
- Hjort, Elisabeth, 1975-
(författare)
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Förtvivlade läsningar : Litteratur som motstånd och läsning som etik
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study has two aims and addresses two areas of investigation. The first aim is to examine, in four novels and their textual worlds, what role is played by collective self-images and essentialist identities in maintaining power structures in regard to gender, class, norms for mental functions, and ethnicity. Whether, and if so, how, the novel’s deconstruction of language and images can function as resistance to hegemonic oppression? What does the encounter between the privileged collective and the marginalized look like in the novel, and what happens in this encounter?The project’s second aim is to probe what criticism of, and what strategies for resistance to, various power structures reading can provide. To what extent is it possible to speak of responsibility for, and in, the reading of fictional works? What role is played by the (un)expected and the conditionality in the poetical novel’s ethical demands on the reader? What might reading as an ethical practice mean and entail? The dual aim situates this dissertation in an interdisciplinary field between ethics, literary studies and aesthetics.In this study despair is the fundament on which the ethical reader stands to approach literature. Rather than discovering meanings, finding examples, or experiencing empathy, it is being engaged in the conditions determined by suffering and injustice that constitutes ethical reading.The novels Drömfakulteten (The Dream Faculty) by Sara Stridsberg, Hevonen häst (Hevonen Horse) by Annika Korpi, Montecore by Jonas Hassen Khemiri, and Personliga pronomen (Personal Pronouns) by Daniel Sjölin comprise the material for the study. They are analysed in terms of deconstructive hermeneutics. Theories brought to bear are primarily Gayatri Spivak’s post-colonial and Emmanuel Levinas’ phenomenological thinking about ethics, together with ideas from, among others, Derek Attridge, Judith Butler, and Sara Ahmed.The readings of the novels are done via four points of entry: identity, the body, the human, and the post-political, as part of the project’s work process, with each reading leading to new questions and critical interventions.The analysis points to a responsibility in relation to identity, a practice where oneself is shifted and transformed. This responsibility also encompasses accountability for the normative orders that need to be changed. Literary projects per se cannot achieve this, but they can be read as a stab at resistance, material for the reader to elaborate upon. This responsibility is an ethical practice that is not completed, that has uncertainty inscribed in its very essence, and that is reinvigorated with each new reading.
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| 10. |
- Hoff Rudhult, Maria
(författare)
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SIDA VID SIDA? : Svenska företag i biståndsverksamheten, 1946–2013
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis studies how the way private businesses were viewed came to affect their participation, and thus role, in Swedish development aid activities in the 1946-2013 period. The role is here viewed in terms of the relationship between “the public” and “the private”. The relationship between public and private activities, as well as the distinction between them, is mutable, and needs to be understood within the framework of a specific context. This, in turn, means that these relationships between the state, in the form of public activity, and the businesses, in the form of private activity, constitute the more comprehensive research problem of the thesis. The analytical strategy of the thesis is based on a discourse theoretical approach, discursive institutionalism, to study how development aid, based on the ideal of “solidarity”, was formulated, established and upheld as an area of policy, focusing especially on the role that was concurrently created for Swedish private businesses. The application of a genealogical approach in the reading of political texts as well as archival material, reports and evaluations, makes visible how the businesses have been part of the Swedish developmental aid activities during practically the entirety of the time period studied, and that this has not been openly accounted for in the public political material. The study shows that upholding the ideal of the “solidarity-based” politics regarding development aid was enabled by applying different logics of action to different parts of the development aid activity. This is made clear by the political ability to involve businesses in development aid activities without having to expressly renounce the position of solidarity. The result of the thesis also shows that the ideal of “solidarity” influenced both the preconditions for distinctions between public and private, and how views of businesses as illegitimate or legitimate actors in development aid activity changed over time.
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