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- Holmberg, Johan, 1994-
(författare)
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Essays on earnings formation, labor market dynamics, and taxation
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chapter [I] analyses the dynamic properties of life-cycle earnings of men and women in Sweden by fitting a model to the covariance structure of earnings. We find that the financial crisis of 2008 did not have any major impact on the variability of earnings and that the upward trend in permanent earnings inequality observed in Sweden during the 1990s does not continue in the 2000s. Using the model to simulate the accumulation of income pension entitlements, we find that college-educated workers have smaller variations in pension entitlements than workers with less education.Chapter [II] presents a life-cycle earnings dynamics model that includes endogenous employment and job change. The model is estimated on Swedish register data using indirect inference. By simulating data from this model, we study the macroeconomic consequences of transitory shocks to unemployment risk, how unemployment at different ages affects the accumulation of pension entitlements, and analyze how different factors contribute to earnings inequality. We find that transitory aggregate shocks to unemployment risk have long-lasting negative effects on employment and earnings, that becoming unemployed at age 40 has a large negative effect on pension accumulations, and that unobserved individual heterogeneity contributes substantially to the observed life-cycle earnings inequality for both men and women in Sweden.Chapter [III] presents a model of earnings dynamics that includes transitions in and out of employment and business cycle fluctuations. The model is estimated using indirect inference and a mix of Swedish register, survey and macro data. We find that the transitions from unemployment to employment are more sensitive to business cycle fluctuations than the probability of remaining employed. By simulating data from the model, we find that the business cycle has a relatively small impact on earnings inequality in Sweden and that young workers are more sensitive to business cycle fluctuations than older workers.Chapter [IV] deals with optimal nonlinear taxation of income and profits in a general equilibrium model with frictional unemployment. We find that the government can achieve redistribution of income through taxation without distorting production efficiency. This outcome is possible if the government uses two nonlinear tax instruments, taxing profits and labor income separately. The results also show that including involuntary unemployment creates an incentive to tax entrepreneurial income at lower marginal rates and labor income at higher marginal rates than otherwise.
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- Frankel, Jennifer, 1981-
(författare)
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Characterization of the MRI patient exposure environment and exposure assessment methods for magnetic fields in MRI scanners
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Magnetic resonance imaging (MRI) has become one of the most common imaging modalities available in modern medicine, and it is an indispensable diagnostic tool thanks to the unparalleled soft-tissue contrast and high image resolution. It is also a unique exposure environment consisting of a complex mix of magnetic fields. During an MRI scan, the patient is simultaneously exposed to a strong static magnetic field, a fast-switching gradient magnetic field, and a pulsed radiofrequency (RF) magnetic field. Transient acute effects, such as nerve excitation and tissue heating, are well known and limited by universal safety guidelines. Long-term health effects related to MRI exposure have, however, not been scientifically established, and no interaction mechanisms have been verified, despite a growing body of research on electromagnetic field exposure. Further epidemiological and experimental research on MRI exposure has been recommended but the lack of a common definition of dose or exposure metric makes evaluation of past research and the design of future experiments difficult.The objectives of this thesis were to characterize the MRI patient exposure environment in terms of the magnetic fields involved, suggest relevant exposure metrics, and introduce exposure assessment methods suitable for epidemiological and experimental research on MRI and long-term health effects.In Paper I, we discussed the MRI exposure environment and its complexity and gave an overview of the current scientific situation. In Paper II, we investigated the exposure variability between different MRI sequences and suggested patient-independent exposure metrics that describe different characteristics of the magnetic field exposure, including mean, peak, and threshold values. In Paper III, we presented three exposure assessment methods, specifically suited to the complex MRI exposure environment: a measurement-based method, a calculation-based method, and a proxy method.Papers I and II showed that MRI exams are not homogenous in terms of exposure, and exposure variability exists between the individual sequences that comprise an exam. Differences in mean exposure between sequences were several-fold, peak exposure differences up to 30-fold, and differences in threshold exposure were in some cases more than 100-fold. Furthermore, within-sequence exposure variability, related to the parameter adjustments that can be made at the scanner console before the start of a scan, gave rise to 5-to-8-fold exposure increases. Paper III showed that magnetic field models could be used to approximate the exposure at arbitrary locations inside the scanner, with slight underestimation of gradient field metrics and large variability in some RF field metrics. With improvements in accuracy and efficiency, the method could become a useful exposure assessment tool for in vitro and in vivo research as well as clinical work on medical implant safety. Our search for suitable exposure metric proxies resulted in a limited selection with low correlation between proxies and their counterpart metrics, but, with further development, the proxy method has the potential to allow for much needed exposure classification relevant to large-scale epidemiological research.The work in this thesis has contributed to increased awareness of the unique MRI exposure environment, the characteristics of the magnetic fields involved, and the inherent exposure variability in MRI exams. The metrics and methods presented are specifically suited to exposure assessment of the unique MRI environment, and may contribute to improved research quality by allowing for meaningful comparisons between study results and for experimental conditions to be easily replicated in future studies.
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- Gunnarsson, Gunnar, 1976-
(författare)
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Survival patterns and density-dependent processes in breeding mallards Anas platyrhynchos
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Measuring and assessing vital rates such as births and deaths are prerequisites for understanding population dynamics. Vital rates may be affected by the density of individuals, even though the importance of density dependence on population dynamics has been debated for a long time. The mallard Anas platyrhynchos is one of the foremost game species in the Holarctic, with millions of birds in hunters’ bags annually. Still, basic knowledge about regulation of mallards’ vital rates is poor, and experimental studies on this topic are rare.In this thesis I have studied survival patterns and density dependence in mallards breeding in Sweden and Finland. Long-term ringing data from both countries were analysed for mortality patterns and causation, as well as for e.g. survival rate estimation. Most of the studies were, though, experiments run over two years involving manipulations of the density of nests, broods and/or adults, in southern and northern Sweden, comprising different biotic regions. Common response variables were survival of nests, ducklings and hens, mainly analysed with program MARK.About 90% of the recovered mallards in Finland and Sweden were hunting kills. However, survival rates were high, ranging from 0.66 to 0.81 for most groups (sex*age). The generality of density dependence was evident since such processes were detected in all studies. Consequently, depredation rate was higher in high nest density compared to low nest density. Survival of ducklings was density-dependent in both boreal and nemoral biotic regions, with food limitation being evident in the former region but not in the latter. In spite of their generality, density-dependent patterns varied within as well between years, and for nest predation rates also between landscape types.The findings about density dependence in breeding mallards in this thesis are novel since they are based on experiments. They are potentially of general interest for management because they embrace a variety of lakes in two geographically distant areas, each being representative for large temperate areas in the northern hemisphere. Detection of density dependence at the local scale may be important at larger scales, too, following the principle of ‘ideal preemptive distribution’ in a source-sink dynamic system.
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- Gunnarsson, Gunnar
(författare)
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Survival patterns and density-dependent processes in breeding mallards Anas platyrhynchos
- 2007
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Doktorsavhandling (populärvet., debatt m.m.)abstract
- Measuring and assessing vital rates such as births and deaths are prerequisites for understanding population dynamics. Vital rates may be affected by the density of individuals, even though the importance of density dependence on population dynamics has been debated for a long time. The mallard Anas platyrhynchos is one of the foremost game species in the Holarctic, with millions of birds in hunters’ bags annually. Still, basic knowledge about regulation of mallards’ vital rates is poor, and experimental studies on this topic are rare. In this thesis I have studied survival patterns and density dependence in mallards breeding in Sweden and Finland. Long-term ringing data from both countries were analysed for mortality patterns and causation, as well as for e.g. survival rate estimation. Most of the studies were, though, experiments run over two years involving manipulations of the density of nests, broods and/or adults, in southern and northern Sweden, comprising different biotic regions. Common response variables were survival of nests, ducklings and hens, mainly analysed with program MARK. About 90% of the recovered mallards in Finland and Sweden were hunting kills. However, survival rates were high, ranging from 0.66 to 0.81 for most groups (sex*age). The generality of density dependence was evident since such processes were detected in all studies. Consequently, depredation rate was higher in high nest density compared to low nest density. Survival of ducklings was density-dependent in both boreal and nemoral biotic regions, with food limitation being evident in the former region but not in the latter. In spite of their generality, density-dependent patterns varied within as well between years, and for nest predation rates also between landscape types. The findings about density dependence in breeding mallards in this thesis are novel since they are based on experiments. They are potentially of general interest for management because they embrace a variety of lakes in two geographically distant areas, eachbeing representative for large temperate areas in the northern hemisphere. Detection of density dependence at the local scale may be important at larger scales, too, following the principle of ‘ideal preemptive distribution’ in a source-sink dynamic system.
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- Hjalmarson, Jenny, 1974-
(författare)
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Ergonomics at Home : Design for Safe Living and Home Care
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The home should represent safety and security for the person who lives there, and this is an important factor for independence and autonomy in very old age. With aging populations, the needs for long-term care increase, care provided by spouses and/or from the growing home care sector. Injuries among these groups are common.In this study, an ergonomics perspective was applied in the analysis of some basic daily activities performed by old persons and by home care workers, assisting.The postures and movements of home care staff assisting at toilet visits, and transferring persons from wheelchair to toilet, were measured and analysed.Some daily activities related to making food and washing clothes, performed by a group of persons between the age of 75 and 100, were measured and analysed.The task of getting up from the floor – on your own and with the help of a walker equipped with a lifting device – was analysed with the help of older persons and nursing staff. The design was built on the knowledge gained from analysing how older people get up from floor.Requirements for access with a four-wheeled walker in the local built environment were investigated.Observations were made with the help of video recording. Postures were recorded with the CUELA measurement system. The VIDAR ergonomics evaluation instrument was used to register the participants’ experiences of discomfort and pain during getting up from the floor with or without the walker with a lifting device. Structured interviews were used to find out about older peoples’ experience of using the four-wheel walker.It is concluded that ageing at home requires improved architectural and technical bathroom design and improved access in the local built environment.
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- Lundberg, Arvid, 1985-
(författare)
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Openness as Political Culture : The Arab Spring and the Jordanian Protest Movements
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study is an exploration of the origins of the Arab Spring in Jordan and across the region. Based on ethnographic fieldwork among the leadership of the Jordanian protest movements, it suggests a new way of understanding why these movements fell apart. A recurrent theme in accounts of the political movements that emerged in Jordan and the Arab world more generally in 2011 is that the unity that initially appeared on streets and squares never transformed into a viable coalition but instead dissolved. A common way to understand why the Arab Spring’s promise of a less authoritarian society was not fulfilled is to look at the center of a political system and explain why it did not become more democratic. These explanations depend on an alternative that we know only through our counterfactual imagination: a united opposition capable of bringing about a democratic system. Instead of imagining a united opposition and explaining why it was not realized, the thesis starts with the fact that the Jordanian opposition was deeply fragmented, but that there were attempts to counter this fragmentation by coordinating and specifying its demands. These attempts fell apart due to something more general than ideological, ethnic or religious divisions within the Jordanian opposition. They were based on a way of conducting politics that was uncommon among the leadership of the protest movements as well as among their opponents. These attempts were characterized by an emphasis on political ideas and programs rather than patronage and by an orientation toward political dialogue, which some Jordanians described in terms of “infitāḥ” (openness) and contrasted with a more polemical form of politics. This ethnographic study puts this more unusual form of politics into sharper relief and shows how it was rooted in political practices and values as well as comparable types of education and social life. This allows us to see how democratization is a movement that is not only political but also cultural, which takes shape in political activism, education and social life.
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