| 1. |
- Andersson, Magnus, 1975-
(författare)
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Construction of force measuring optical tweezers instrumentation and investigations of biophysical properties of bacterial adhesion organelles
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optical tweezers are a technique in which microscopic-sized particles, including living cells and bacteria, can be non-intrusively trapped with high accuracy solely using focused light. The technique has therefore become a powerful tool in the field of biophysics. Optical tweezers thereby provide outstanding manipulation possibilities of cells as well as semi-transparent materials, both non-invasively and non-destructively, in biological systems. In addition, optical tweezers can measure minute forces (< 10-12 N), probe molecular interactions and their energy landscapes, and apply both static and dynamic forces in biological systems in a controlled manner. The assessment of intermolecular forces with force measuring optical tweezers, and thereby the biomechanical structure of biological objects, has therefore considerably facilitated our understanding of interactions and structures of biological systems. Adhesive bacterial organelles, so called pili, mediate adhesion to host cells and are therefore crucial for the initial bacterial-cell contact. Thus, they serve as an important virulence factor. The investigation of pili, both their biogenesis and their expected in vivo properties, brings information that can be of importance for the design of new drugs to prevent bacterial infections, which is crucial in the era of increased bacterial resistance towards antibiotics. In this thesis, an experimental setup of a force measuring optical tweezers system and the results of a number of biomechanical investigations of adhesive bacterial organelles are presented. Force measuring optical tweezers have been used to characterize three different types of adhesive organelles under various conditions, P, type 1, and S pili, which all are expressed by uropathogenic Escherichia coli. A quantitative biophysical force-extension model, built upon the structure and force response, has been developed. It is found, that this model describes the biomechanical properties for all three pili in an excellent way. Various parameters in their energy landscape, e.g., bond lengths and transition barrier heights, are assessed and the difference in behavior is compared. The work has resulted in a method that in a swift way allows us to probe different types of pili with high force and high spatial resolution, which has provided an enhanced understanding of the biomechanical function of these pili.
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| 2. |
- Andersson, Sten-Ove, 1953-
(författare)
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Militär akutsjukvård i fält : när den övade verkligheten blir verklig
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aims: Governing for the Armed Forces health care is respect for human dignity and the view of each individual as irreplaceable. The quality of the military care will be at a level equivalent to that of today's civil peace healthcare, which requires that the training is of high quality. Casualty care in the military environment is a complex, challenging and dangerous task. Today there is a lack of knowledge about how to learn these skills. The purpose of the research was to identify the knowledge area pre-hospital care in the military environment by examining what doctors, nurses, paramedics and officers learn about military health care during preparation and exercise.Method: A phenomenographic approach was used in all sub-studies, and empirical data were collected by means of semi-structured interviews. Study I‐III are cross-sectional studies and study IV is a longitudinal study. Twelve registered nurses who had served in Bosnia were interviewed for study I, and 24 conscript paramedics were interviewed for study II. Study III included 20 officers in their pre-deployment training for service in Afghanistan and Liberia, and Study IV included 7 doctors and twenty nurses who previously had served in Afghanistan, Bosnia, Kosovo and Liberia.Results: Learning military health care by training and gaining experience can be seen as different abilities; interaction, action and reflection. In-depth analysis at a meta--‐level revealed that the integration between the military and military medical fields of knowledge was missing. The results indicate that participants' understanding of their respective fields of knowledge is inadequate and needs to be integrated in education in a clearer way.Implications: To create opportunities for better education and integration in these fields of knowledge are proposed (1) that the findings of the thesis could be utilised to develop the design of the curriculum (2) the inter-professional learning is introduced as a part of creating a safer and more effective pre-hospital care, (3) the clinical competence becomes part of the development of pre-hospital emergency care in the field, and (4) that the training is built according to the principle of "train as you fight" with emphasis on the requirements in the combat zone.
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| 3. |
- B. Brant Carvalho, Paulo H., 1990-
(författare)
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Pressure-Induced Amorphization and Distinct Amorphous States of Clathrate Hydrates
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis summarizes a study on the pressure-induced amorphization (PIA) and structures of amorphous states of clathrate hydrates (CHs).PIA involves the transition of a crystalline material into an amorphous solid in response of mechanical compression at temperatures well below the melting point. The first material observed to undergo PIA was hexagonal ice. More recently it was shown that compounds of water undergo the same phenomenon without decomposition, despite the presence of solutes. CHs, which are crystalline inclusion compounds consisting of water molecules encaging small guest species, undergo PIA at ca. 1–4 GPa below 145 K. The obtained amorphous CH phase can be further densified on isobaric heating at high pressure. This annealing step enables to retain an amorphous material on pressure release. There has been a significant amount of studies into the understanding of the nature of PIA and transformations between amorphous phases of pure ice. The aim of this thesis has been the understanding of the PIA in CHs and its relation to pure ice. New information on the nature of PIA and subsequent amorphous-amorphous transitions in CH systems were gained from structural studies and in situ neutron diffraction played pivotal role due to the sensitivity of neutrons to the light element hydrogen. Here a generalized understanding of the PIA in CHs and a clear image of amorphous CH structures are presented.
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| 5. |
- Pontoni, Angèle, 1994-
(författare)
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Development and simulated observations of the Jovian Neutrals Analyzer
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the development of the Jovian Neutrals Analyzer (JNA) for the Jupiter ICy moons Explorer (JUICE) mission to Jupiter, planned to launch in 2023. Jupiter, the largest planet in the Solar System, orbits the Sun at five times the distance from the Earth to the Sun, accompanied by dozens of moons, rings, and the largest object in the SolarSystem: the Jovian magnetosphere. Born of the interaction betweenthe solar wind and Jupiter’s strong magnetic field, the Jovian magneto-sphere is host to a number of unique, complex phenomena, includingthe creation of a sheet of energetic particles orbiting the giant planetand interacting with its four largest moons: Io, Europa, Ganymede, and Callisto.A better understanding of Jupiter’s magnetosphere and its interaction with its four largest moons is one of the main objectives of the JUICE mission. To achieve this goal, JUICE is equipped with the Particle Environment Package (PEP), comprised of six particle sensors, including JNA. By measuring low-energy Energetic Neutral Atoms (ENAs) in the range from 10 eV to 3.3 keV, JNA will image the plasma co-located with the orbit of Io, and reveal ion precipitation patterns at the surface of Jupiter’s icy moons.JNA improves on its predecessors (CENA on Chandrayaan-1 and ENA on BepiColombo) by featuring a higher angular resolution, with a 150◦ field-of-view divided into 11 pixels. JNA is also more resistant to radiation, a necessary improvement to be able to make measurements in the harsh radiation environment expected in the Jovian system. To measure ENAs in the low-energy range, JNA uses a charged particle deflector to remove ambient ions; a charge conversion surface to ionize incoming neutral particles, which are then energy-analyzed by an electrostatic wave system; and a Time-of-Flight cell to derive the mass of the original particle.In this work, we report on how JNA was designed, developed, and calibrated. We show the first results of JNA’s calibration campaign, and compare them to its expected performance. Finally, to facilitate the interpretation of JNA data at Jupiter, we estimate ENA fluxes expected at Ganymede and use our results to simulate JNA observations.
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| 6. |
- Riesbeck, Eva, 1947-
(författare)
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På tal om matematik : matematiken, vardagen och den matematikdidaktiska diskursen
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this dissertation is to describe and analyze how discourse as a theoretical and didactical concept can help in advancing knowledge about the teaching of mathematics in school. The dissertation has been written within a socio-cultural perspective where active participation and support from artefacts and mediation are viewed as important contributions to the development of understanding. Discourse analysis was used as a theoretical point of departure to grasp language use, knowledge construction and mathematical content in the teaching practises. The collection of empirical data was made up of video and audio tape recordings of the interaction of teachers and pupils in mathematics classrooms when they deal with problem-solving tasks, as well as discussions between student teachers as they engage in planning a teaching situation in mathematics. Discourse analysis was used as a tool to shed light upon how pupils learn and develop understanding of mathematics.The results of my studies demonstrate that discussions very often are located in either a mathematical or in an every-day discourse. Furthermore, the results demonstrate how change between every-day and mathematical language often takes place unknowingly. Also the results underline that a specific and precise dialogue can contribute towards teachers’ and pupils’ conscious participation in the learning process. Translated into common vocabulary such as speak, think, write, listen and read teachers and pupils would be able to interact over concepts, signs, words, symbols, situations and phenomena in every-day discourse and its mathematical counterpart. When teachers and pupils become aware of discursive boundary crossing in mathematics an understanding of mathematical phenomena can start to develop. Teachers and pupils can construct a meta-language leading to new knowledge and new learning in mathematics.
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| 7. |
- Svensson, Maria, 1980-
(författare)
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Assessing the ERG rearrangement for clinincal use in patients with prostrate cancer
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, close to 10 000 men are annually diagnosed with prostate cancer (PCa) and approximately 2400 men die of their disease each year. Today there is no reliable marker that can separate patients who will have an aggressive type of disease that requires treatment, from patients who will have a more indolent clinical course and can be left untreated. This further leads to the current problem of over treatment of men with PCa. Hence, there is an urgent need for reliable prognostic markers that can be used at time of diagnosis. With the discovery of recurrent gene rearrangements in PCa, most commonly ERG rearrangements, hope came that this aberration could play a role in diagnosis and/or prognosis of the disease.The aim of this thesis was to investigate the clinical implication of ERG rearrangements in the management of PCa.The work in this thesis supports the findings from previous studies, suggesting that the ERG rearrangement is a sign of a more aggressive type of cancer. The major findings are that in multifocal PCa, the ERG rearranged cancer foci are more prone to metastatic dissemination compared to foci without the ERG rearrangement and that patients harboring the ERG rearrangement have a faster disease progression leading up to earlier start of hormonal treatment. Furthermore, the results add an additional level of complexity in a subset of PCa tumors that harbor multiple gene rearrangements on the cellular level. The result also show that the newly available ERG antibody is highly predictive of ERG rearrangement and is appropriate to use when faced with limitations in tissue amounts.The findings in this thesis indicate that the ERG rearrangement has a potential role in the clinical management of PCa but further studies arerequired.
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| 8. |
- Tonpheng, Bounphanh, 1959-
(författare)
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Thermal and mechanical studies of carbon nanotube-polymer composites synthesized at high pressure and high temperature
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, thermal and mechanical properties of polymers and carbon nanotubes-polymer composites, which were modified and studied under high pressure, are presented. The results concern the thermal conductivity κ and heat capacity per unit volume ρcp of pure polymers: polyisoprene (PI), polybutadiene (PB), and nylon-6, and their multi-wall and single-wall carbon nanotube (MWCNT and SWCNT) composites both before (untreated) and after high pressure treatments. As shown here, a suitable high pressure high temperature (HP&HT) treatment induces either cross-links in the polymers (PI and PB), i.e. transforms these into elastomers, or increases the crystallinity (nylon-6). The experiments were done, in situ, in the temperature range 100-520 K for pressures up to 1.5 GPa, and the results show that cross-linking under high pressure can be monitored in data for κ and ρcp. Moreover, κ for a well cross-linked (ebonite-like) polymer near ambient conditions can be up to 50% higher than the untreated states, whereas ρcp becomes similar as the glassy state of the untreated polymer. The glass transition of the cross-linked states becomes broader and shifts to higher temperatures with increasing degree of cross-linking. In the case of nylon-6, the HP&HT treatment causes microstructural changes, viz. increased crystallinity and crystals with a preferred orientation and increased size, which enhances κ and improves the thermal stability. The thermal property studies of the CNT polymer composite show that k of the composites increases significantly, e.g. 120% for 5wt% SWCNTs in PI, which is attributed to the very high k of CNTs. Moreover, MWCNTs also improve k, but not as much as SWCNTs. This is accounted for by their lower aspect ratio (length/diameter), whereas their lower k is less important. Adding CNTs normally raise the glass transition temperatures of the polymers. More specifically, SWCNTs in PB raise the glass transition temperature slightly more than MWCNTs and, in particular, under the most densified conditions and for a high molecular weight PB, which may be due to more favorable conditions for coating/wrapping of the CNTs. The mechanical studies of the HP&HT treated polymers and composites show that CNTs strongly enhances the tensile strength and Young’s modulus, e.g. 5 wt% SWCNT in PI synthesized at 1 GPa and 513 K showed 2 times higher tensile strength and 2.3 times higher Young’s modulus than that of similarly treated pure PI. The results indicate that the treatment improves the poor interfacial contact between the CNTs and polymer, which is one of the obstacles for achieving stronger CNT composites
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