| 1. |
- Aagaard, Sunniva Margrethe Due
(författare)
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Reticulate Evolution in Diphasiastrum (Lycopodiaceae)
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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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| 2. |
- Aalto, Aino-Maija
(författare)
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Incentives and Inequalities in Family and Working Life
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)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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| 3. |
- Aare, Sudhakar Reddy, 1978-
(författare)
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Intensive Care Unit Muscle Wasting : Skeletal Muscle Phenotype and Underlying Molecular Mechanisms
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Acute quadriplegic myopathy (AQM), or critical illness myopathy, is a common debilitating acquired disorder in critically ill intensive care unit (ICU) patients characterized by generalized muscle wasting and weakness of limb and trunk muscles. A preferential loss of the thick filament protein myosin is considered pathognomonic of this disorder, but the myosin loss is observed relatively late during the disease progression. In attempt to explore the potential role of factors considered triggering AQM in sedated mechanically ventilated (MV) ICU patients, we have studied the early effects, prior to the myosin loss, of neuromuscular blockade (NMB), corticosteroids (CS) and sepsis separate or in combination in a porcine experimental ICU model. Specific interest has been focused on skeletal muscle gene/protein expression and regulation of muscle contraction at the muscle fiber level. This project aims at improving our understanding of the molecular mechanisms underlying muscle specific differences in response to the ICU intervention and the role played by the different triggering factors.The sparing of masticatory muscle fiber function was coupled to an up-regulation of heat shock protein genes and down-regulation of myostatin are suggested to be key factors in the relative sparing of masticatory muscles. Up-regulation of chemokine activity genes and down-regulation of heat shock protein genes play a significant role in the limb muscle dysfunction associated with sepsis. The effects of corticosteroids in the development of limb muscle weakness reveals up-regulation of kinase activity and transcriptional regulation genes and the down-regulation of heat shock protein, sarcomeric, cytoskeletal and oxidative stress responsive genes. In contrast to limb and craniofacial muscles, the respiratory diaphragm muscle responded differently to the different triggering factors. MV itself appears to play a major role for the diaphragm muscle dysfunction. By targeting these genes, future experiments can give an insight into the development of innovative treatments expected at protecting muscle mass and function in critically ill ICU patients.
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| 4. |
- Aarnio, Mikko
(författare)
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Visualization of Peripheral Pain Generating Processes and Inflammation in Musculoskeletal Tissue using [11C]-D-deprenyl PET
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An objective visualization and quantification of pain-generating processes in the periphery would alter pain diagnosis and represent an important paradigm shift in pain research. Positron emission tomography (PET) radioligand [11C]-D-deprenyl has shown an elevated uptake in painful inflammatory arthritis and whiplash-associated disorder. However, D-Deprenyl’s molecular binding target and uptake mechanism in inflammation and musculoskeletal injuries are still unknown. The present thesis aimed to gain insight into the mechanisms of D-deprenyl binding and uptake and to verify whether pain-associated sites and inflammation in acute musculoskeletal injury could be visualized, objectively quantified and followed over time with [11C]-D-deprenyl PET-computed tomography (PET/CT).To identify the D-deprenyl binding target, a high-throughput analysis and competitive radioligand binding studies were performed. D-deprenyl inhibited monoamine oxidase A (MAO-A) activity by 55%, MAO-B activity by 99% and angiotensin-converting enzyme (ACE) by 70%, which identified these enzymes as higher-affinity targets. Furthermore, radioligand receptor binding assays pointed favorably towards the concept of MAO-B as the primary target. To investigate the biochemical characteristics of the binding site, we used radioligand binding assays to assess differences in the binding profile in inflamed human synovial membranes exhibiting varying levels of inflammation. D-deprenyl bound to a single, saturable population of membrane-bound protein in synovial membrane homogenates and the level of inflammation correlated with an increase in D-deprenyl binding affinity.To verify whether D-deprenyl can visualize pain-generating processes, patients with musculoskeletal injuries were investigated and followed-up with [11C]-D-deprenyl PET/CT. In the study of eight patients with ankle sprain, the molecular aspects of inflammation and tissue injury could be visualized, objectively quantified and followed over time with [11C]-D-deprenyl PET/CT. The pain coexisted with increased [11C]-D-deprenyl uptake. In the study of 16 whiplash patients, an altered [11C]-D-deprenyl uptake in the cervical bone structures and facet joints was associated with subjective pain levels and self-rated disability.To further evaluate D-Deprenyl’s usefulness as a marker of inflammation, three PET tracers were compared in an animal PET/CT study. Preliminary findings showed that [11C]-D-deprenyl had an almost identical uptake pattern when compared with [11C]-L-deprenyl. The two deprenyl enantiomers showed no signs of specific binding or trapping and therefore may not be useful to study further in models of inflammatory pain, surgical pain, or both.This thesis demonstrates that D-deprenyl visualizes painful inflammation in musculoskeletal injuries and that the probable underlying mechanism of [11C]-D-deprenyl uptake is binding to MAO.
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| 5. |
- Aarnio, Riina
(författare)
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Self-sampling for HPV testing in primary cervical screening : Including clinical and health economic aspects
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Persistent infection with high-risk human papillomavirus (HPV) is a prerequisite for the development of cervical cancer. HPV testing has higher sensitivity for high-grade cervical intraepithelial neoplasia (CIN2+) than cytology, resulting in more effective screening. As HPV testing also offers an opportunity for self-sampling, it could serve as an even more effective and cost-effective method of cervical screening.First, we compared repeated self-sampling for HPV testing with Pap smear cytology in detection of CIN2+ in primary cervical screening for women aged 30–49 years (n=36 390). We found a more than twofold higher detection rate of CIN2+ and a fourfold higher detection rate of CIN2 with self-sampling compared with cytology. However, no difference was seen between the arms in the detection rate of CIN3+. It thus seems that CIN is detected at an earlier stage with self-sampling than with cytology, but the impact of this needs to be further explored.Second, as management of HPV-positive women with normal cytology results is a challenge, we wanted to evaluate the proportion of cases of histological CIN2+ in these women. In this prospective study we performed LEEP and found that 15% (6/40) of the women had undetected CIN2+. These findings can be used in counseling women about the risk of cervical cancer and helping clinicians in decisions on management.Third, we performed a cost-effectiveness analysis on the same study population as in Study I. Self-sampling for HPV testing resulted in a higher participation rate and more detected cases of CIN2+ at a lower cost and was regarded as more cost-effective than Pap smear cytology in cervical screening. These results can guide policy-makers when planning future screening programs.Fourth, we compared self-sampling with sampling by medical professionals for HPV testing in detection of CIN2+, using a combination of an FTA card as storage medium and a PCR-based HPV test (hpVIR) in women aged 30–60 years (n=11 951). No difference in the detection rates of histological CIN2+ was found between the arms.Taken together, self-sampling resulted in a higher participation rate than sampling by medical professionals in cervical screening and that triage with repeated self-sampling resulted in high compliance and detection rate of CIN2+. As repeated self-sampling for HPV testing was also cost-effective, it could serve as an attractive alternative in the development of future cervical screening programs. More research is needed on how to refine the management of HPV-positive women by self-sampling only.
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| 6. |
- Aarts, Clara
(författare)
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Exclusive breastfeeding-Does it make a difference? : A longitudinal, prospective study of daily feeding practices, health and growth in a sample of Swedish infants
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The concept of exclusive breastfeeding in relation to daily feeding practices and to health and growth of infants in an affluent society was examined. In a descriptive longitudinal prospective study 506 mother-infant pairs were followed from birth through the greater part of the first year. Feeding was recorded daily, and health and growth were recorded fortnightly. Large individual variations were seen in breastfeeding patterns. A wide discrepancy between the exclusive breastfeeding rates obtained from "current status" data and data "since birth" was found.Using a strict definition of exclusive breastfeeding from birth and taking into account the reasons for giving complementary feeding, the study showed that many exclusively breastfed infants had infections early in life, the incidence of which increased with age, despite continuation of exclusive breastfeeding. However, truly exclusively breastfed infants seem less likely to suffer infections than infants who receive formula in addition to breast milk. Increasing formula use was associated with an increasing likelihood of suffering respiratory illnesses. The growth of exclusively breastfed infants was similar to that of infants who were not exclusively breastfed. The health of newborn infants during the first year of life was associated with factors other than feeding practices alone. Some of these factors may be prenatal, since increasing birth weight was associated with an increasing likelihood of having respiratory symptoms, even in exclusively breastfed infants. However, exclusive breastfeeding was shown to be beneficial for the health of the infant even in an affluent society.
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| 7. |
- Abbas, Qaisar, 1975-
(författare)
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Weak Boundary and Interface Procedures for Wave and Flow Problems
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems.The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries over to the fully nonlinear case.The work was complemented to include the new idea of using WBCs on multiple grid points in a region, where the data is known, instead of at a single point. It was shown that we can achieve high accuracy, an increased rate of convergence to steady-state and non-reflecting boundary conditions by using this approach.Using the SBP technique and WBCs, we have worked out how to construct conservative and energy stable hybrid schemes for shocks using two different approaches. In the first method, we combine a high order finite difference scheme with a second order MUSCL scheme. In the second method, a procedure to locally change the order of accuracy of the finite difference schemes is developed. The main purpose is to obtain a higher order accurate scheme in smooth regions and a low order non-oscillatory scheme in the vicinity of shocks.Furthermore, we have analyzed the energy stability of the MUSCL scheme, by reformulating the scheme in the framework of SBP and artificial dissipation operators. It was found that many of the standard slope limiters in the MUSCL scheme do not lead to a negative semi-definite dissipation matrix, as required to get pointwise stability.Finally, high order simulations of shock diffracting over a convex wall with two facets were performed. The numerical study is done for a range of Reynolds numbers. By monitoring the velocities at the solid wall, it was shown that the computations were resolved in the boundary layer. Schlieren images from the computational results were obtained which displayed new interesting flow features.
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| 8. |
- Abbasian, Saeid, 1961-
(författare)
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Integration på egen hand : En studie av invandrade kvinnoföretagare i Sverige
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The principal aim of this thesis is to discover and analyse the motives that make immigrant women start their own businesses in Sweden and to investigate whether this is a way to achieve integration in working life. The empirical material consists of two types of interviews. One type consisted of interviews with five experts on labour market issues, and the other of interviews with 16 female entrepreneurs of Iranian, Chilean and Turkish origin having their own business in the Greater Stockholm region. Results from the first set of interviews indicate that female immigrants who independently start their enterprise rely mainly on their own resources of power and abilities. They are either women with class resources such as higher educations, previous work experience, language abilities and economic savings, or young women with certificates from high schools or universities. The social environment where they grew up, the gender structure and gender roles in the family before and after immigration and time of residence in Sweden also influence the extent to which women immigrants can act independently. According to the experience of the experts, the motives for starting their business are either different structural reasons, e.g. unemployment, lack of suitable or well-paying jobs, lay-offs etc, or personal reasons such as having a meaningful occupation, to support the family, to earn money of their own, to be independent from men and strive for a better standard of living etc. Results from the second set of interviews indicate that the most important resource these women have used when establishing their businesses is class resources such as education and adequate training, different types of work experiences, human capital and in addition to this economic savings. For many of the women in this sample different structural reasons, like unemployment, lack of good job opportunities, discrimination on work places, merge with personal reasons such as strivings to achieve independence, being one’s own boss, to realize one’s plans and ambitions, when starting their business. Independent entrepreneurship is a good way for immigrant women to be integrated in working life especially if they start within certain branches. These are branches in which the women have appropriate university education or vocational training, previous work experience or which correspond to their personal interests. In addition immigrant women become more integrated if an education received abroad is treated as equivalent to the parallel Swedish education or degree. A further factor promoting integration is if they can fully exploit their capacities when developing their own businesses. These conditions help them to feel much more satisfaction in working life as women identify themselves with their actual profession and feel that they have found the “right place” for themselves in the society.
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| 9. |
- Abbasinejad Enger, Shirin, 1975-
(författare)
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Dosimetry Studies of Different Radiotherapy Applications using Monte Carlo Radiation Transport Calculations
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Developing radiation delivery systems for optimisation of absorbed dose to the target without normal tissue toxicity requires advanced calculations for transport of radiation. In this thesis absorbed dose and fluence in different radiotherapy applications were calculated by using Monte Carlo (MC) simulations.In paper I-III external neutron activation of gadolinium (Gd) for intravascular brachytherapy (GdNCB) and tumour therapy (GdNCT) was investigated. MC codes MCNP and GEANT4 were compared. MCNP was chosen for neutron capture reaction calculations. Gd neutron capture reaction includes both very short range (Auger electrons) and long range (IC electrons and gamma) products. In GdNCB the high-energetic gamma gives an almost flat absorbed dose delivery pattern, up to 4 mm around the stent. Dose distribution at the edges and inside the stent may prevent stent edge and in-stent restenosis. For GdNCT the absorbed dose from prompt gamma will dominate over the dose from IC and Auger electrons in an in vivo situation. The absorbed dose from IC electrons will enhance the total absorbed dose in the tumours and contribute to the cell killing.In paper IV a model for calculation of inter-cluster cross-fire radiation dose from β-emitting radionuclides in a breast cancer model was developed. GEANT4 was used for obtaining absorbed dose. The dose internally in cells binding the isotope (self-dose) increased with decreasing β-energy except for the radionuclides with substantial amounts of conversion electrons and Auger electrons. An effective therapy approach may be a combination of radionuclides where the high self-dose from nuclides with low β-energy should be combined with the inter-cell cluster cross-fire dose from high energy β-particles.In paper V MC simulations using correlated sampling together with importance sampling were used to calculate spectra perturbations in detector volumes caused by the detector silicon chip and its encapsulation. Penelope and EGSnrc were used and yielded similar results. The low energy part of the electron spectrum increased but to a less extent if the silicon detector was encapsulated in low z-materials.
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| 10. |
- Abd-Elrady, Emad, 1970-
(författare)
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Nonlinear Approaches to Periodic Signal Modeling
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Periodic signal modeling plays an important role in different fields. The unifying theme of this thesis is using nonlinear techniques to model periodic signals. The suggested techniques utilize the user pre-knowledge about the signal waveform. This gives these techniques an advantage as compared to others that do not consider such priors. The technique of Part I relies on the fact that a sine wave that is passed through a static nonlinear function produces a harmonic spectrum of overtones. Consequently, the estimated signal model can be parameterized as a known periodic function (with unknown frequency) in cascade with an unknown static nonlinearity. The unknown frequency and the parameters of the static nonlinearity are estimated simultaneously using the recursive prediction error method (RPEM). A treatment of the local convergence properties of the RPEM is provided. Also, an adaptive grid point algorithm is introduced to estimate the unknown frequency and the parameters of the static nonlinearity in a number of adaptively estimated grid points. This gives the RPEM more freedom to select the grid points and hence reduces modeling errors. Limit cycle oscillations problem are encountered in many applications. Therefore, mathematical modeling of limit cycles becomes an essential topic that helps to better understand and/or to avoid limit cycle oscillations in different fields. In Part II, a second-order nonlinear ODE is used to model the periodic signal as a limit cycle oscillation. The right hand side of the ODE model is parameterized using a polynomial function in the states, and then discretized to allow for the implementation of different identification algorithms. Hence, it is possible to obtain highly accurate models by only estimating a few parameters. In Part III, different user aspects for the two nonlinear approaches of the thesis are discussed. Finally, topics for future research are presented.
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