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  • Public defence: 2017-12-14 10:00 Vivi Täckholmsalen (Q-salen) NPQ-huset, Stockholm
    Garcia Lobato Tavares, Raquel
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Host cell responses to Helicobacter pylori secreted factors2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The infection of the human gastric mucosa by the bacterium Helicobacter pylori can lead to the development of gastritis, gastroduodenal ulcers, and cancer. The factors that determine disease development in a small percentage of infected individuals are still not fully understood.

    In this thesis, we aimed to identify and functionally characterize novel virulence factors of H. pylori and to understand their effect on host cell responses.

    In Paper I, we found that JHP0290, an uncharacterized secreted protein of H. pylori, induced macrophage apoptosis concomitant to the release of pro-inflammatory cytokine TNF via the regulation of the Src family of kinases and ERK MAPK pathways. In paper II, we demonstrated that JHP0290 exhibits both proliferative and anti-apoptotic activity, together with a faster progression of the cell cycle in gastric epithelial cells. During these responses, ERK MAPK and NF-κB pathways were activated. Paper III revealed a pro-apoptotic effect of another H. pylori-secreted protein HP1286 in macrophages via the TNF-independent and ERK-dependent pathways. No apoptosis was observed in HP1286-treated T cells or HL60 neutrophil-like cells, suggesting cell-type specific effect of HP1286. In Paper IV, we observed the pro-inflammatory activity of H. pylori secreted protein HP1173 in macrophages. The protein was found to induce TNF, IL-1β, and IL-8 in macrophages through MAPKs, NF-κB, and AP-1 signaling pathways. Furthermore, differential expression and release of JHP0290, HP1286, and HP1173 homologues was observed among H. pylori strains (papers II, III, IV). 

    Due to their ability to regulate multiple host cell responses, proteins JHP0290, HP1286, and HP1173 could play an important role in bacterial pathogenesis.

     

  • Public defence: 2017-12-14 13:00 Nordenskiöldsalen, Geovetenskapens hus, Stockholm
    Raúl Sitoe, Sandra
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Environmental history in southern Mozambique: Reconstruction of flooding events, hydroclimate and sea-level dynamics since mid-Holocene2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this thesis has been to reconstruct paleoenvironment, paleohydrology and paleoclimate in coastal southern Mozambique, with emphasis on tracing past flooding events on the lower Limpopo River floodplain. In order to extend flood chronologies beyond periods covered by instrumental data, sediments from lakes on the floodplain were studied (Lake Lungué, Coassane Oxbow, Lake Magandane and Lake Soane). Past sea-level variations and climate changes were deduced by analyzing sediments from coastal sites north of the floodplain area (Lake Chilau, Lake Nhauhache and Macassa Bay). To achieve the established objectives, a multi-proxy approach was applied on most of the retrieved sediment cores, involving analysis of mineral magnetic parameters, grain-size and organic carbon in combination with analysis of microfossils such as diatoms and/or phytoliths. Chronologies for the constructed time-series analysis were obtained by radiocarbon dating and age-depth modelling. The synthesized data from the sampled sites on the Limpopo River floodplain suggest that the area was affected by at least 16 flooding events of variable magnitudes during the studied period. These are dated to c. AD 940, 980, 1040, 1100, 1250, 1300, 1370, 1580, 1665, 1730, 1755, 1855, 1920, 1945, 1970 and 2000. In calibrated years BP these ages correspond to 1010, 970, 910, 850, 700, 650, 580, 370, 285, 220, 195, 95, 30, and 5 cal yrs BP. The two youngest are dated to 20 and 50 years AP (After Present being 1950). Proxy data further suggest that southern Africa was subject to two periods of sea-level highstands, at c. 5000–4200 BC (6950–6150 cal yrs BP) and AD 300–950 (1650–1000 cal yrs BP). The former represents the middle part of the postglacial climatic optimum. The wettest period in the Limpopo River floodplain was reported between AD 1360 and 1560 (590 and 390 cal yrs BP) in the Lake Lungué record, while Lake Chilau experienced wet conditions between AD 1200 and 1400 (750 and 550 cal yrs BP), then returning to drier conditions that prevailed until c. AD 1600. In Lake Nhauhache, however, drier conditions prevailed from c. AD 1200–1700 (750–250 cal yrs BP), shifting towards wetter at c. AD 1900 (50 cal yrs BP). The deviating signals between records can partly be explained by Lake Lungué basin being located on the Limpopo River floodplain, responding to flooding events associated with precipitation upstream the drainage area. Therefore, wet and dry periods in floodplain lakes (e.g. Lake Lungué) are not expected to correlate with precipitation changes on a local scale, as indicated by e.g. Lake Nhauhache. This is supported by a relatively weak agreement between Lake Lungué record and other nearby records (outside the floodplain), but a better correlation with records from the upper catchment, where a more regional climate signal is provided of the southern African summer rainfall region.

  • Public defence: 2017-12-15 09:30 Vivi Täckholmsalen (Q-salen), NPQ-huset, Stockholm
    Kanatani, Sachie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Host-parasite interactions in the dissemination of Toxoplasma gondii2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Toxoplasma gondii is an obligate intracellular parasite that infects virtually all warm-blooded organisms. Systemic dissemination of T. gondii in the organism can cause life-threatening infection that manifests as Toxoplasma encephalitis in immune-compromised patients. In addition, mounting evidence from epidemiological studies indicates a link between chronic Toxoplasma infection and mental disorders. To better understand the pathogenesis of toxoplasmosis, basic knowledge on the host-parasite interactions and the dissemination mechanisms are essential. Previous findings have established that, upon infection with T. gondii, dendritic cells (DCs) and microglia exhibit enhanced migration, which was termed the hypermigratory phenotype. As a result of this enhanced migration, DCs and microglia are used as vehicle cells for dissemination (‘Trojan horse’) which potentiates dissemination of T. gondii in mice. However, the precise mechanisms behind the hypermigratory phenotype remained unknown. In this thesis, we characterized host-parasite interactions upon infection with T. gondii and investigated the basic mechanisms behind the hypermigratory phenotype of T. gondii-infected DCs and microglia.

    In paper I, we observed that upon infection with T. gondii, DCs underwent rapid morphological changes such as loss of adhesiveness and podosomes, with integrin redistribution. These rapid morphological changes were linked to hypermotility and were induced by active invasion of T. gondii within minutes. T. gondii-infected DCs exhibited up-regulation of the C-C chemokine receptor CCR7 and chemotaxis towards the CCR7 chemotactic cue, CCL19.

    In paper II, we developed a 3-dimensional migration assay in a collagen matrix, which allowed us to characterize the hypermigratory phenotype in a more in vivo-like environment. The migration of T. gondii-infected DCs exhibited features consistent with integrin-independent amoeboid type of migration. T. gondii-induced hypermigration of DCs was further potentiated in the presence of CCL19 in a 3D migration assay.

    In paper III, we identified a parasite effector molecule, a Tg14-3-3 protein derived from parasite secretory organelles. Tg14-3-3 was sufficient to induce the hypermigratory phenotype. Transfection with Tg14-3-3-containing fractions or recombinant Tg14-3-3 protein induced the hypermigratory phenotype in primary DCs and in a microglial cell line. In addition, Tg14-3-3 localized in the parasitophorous vacuolar space and host 14-3-3 proteins were rapidly recruited around the parasitophorous vacuole.

    In paper IV, we found that mouse DCs dominantly express the L-type voltage-dependent calcium channel, Cav1.3. Cav1.3 was linked to the GABAergic signaling-induced hypermigratory phenotype. Pharmacological inhibition of Cav1.3 and knockdown of Cav1.3 abolished the hypermigratory phenotype in T. gondii infected DCs. Blockade of voltage-dependent calcium channels reduced the dissemination of T. gondii in a mouse model.

    In paper V, we showed that microglia, resident immune cells in the brain, also exhibited rapid morphological changes and hypermotility upon infection with T. gondii. However, an alternative GABA synthesis pathway was shown to be involved in the hypermigratory phenotype in microglia.

    In summary, this thesis describes novel host-parasite interactions, including host cell migratory responses and key molecular mechanisms that mediate the hypermigratory phenotype. The findings define a novel motility-related signaling axis in DCs. Thus, T. gondii employs GABAergic non-canonical pathways to hijack host cell migration and facilitate dissemination. We believe that these findings represent a significant step forward towards a better understanding of the pathogenesis of T. gondii infection.

  • Public defence: 2017-12-15 10:00 sal G Arrheniuslaboratorierna, Stockholm
    Boguslaw, Julia
    Stockholm University, Faculty of Social Sciences, Department of Economics.
    When the Kids Are Not Alright: Essays on Childhood Disadvantage and Its Consequences2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis consists of three self-contained essays on childhood disadvantage and its consequences in Sweden.

    A Longitudinal Look at Child Poverty Using Both Monetary and Non-monetary Approaches. In this paper, we broaden the analysis of child poverty by using both monetary and non-monetary measures of poverty and by comparing these over time. We use a composite of questionnaire answers from children regarding possession of socially perceived necessities and participation in social activities to develop two non-monetary child-centric concepts of disadvantage: material deprivation and social exclusion. The empirical analysis is based on two cross-sections and a panel of children in the Swedish Level-of-Living Survey matched with parental survey data and administrative income records. Consistent with previous findings, we find that relative income poverty among children increases significantly between the year 2000 and 2010. The fraction of children that is disadvantaged in two dimensions, monetary and non-monetary, is relatively small (0.9–7.0 percent) but increases significantly during the period of study. The modest size of the overlap suggests that our measures capture different dimensions of disadvantage, thereby pointing to the importance of alternative poverty indicators. We also find that income status in childhood is the best predictor of socio-economic outcomes in young adulthood.

    The Aspirations-attainment Paradox of Immigrant Children: A Social Networks Approach. Using two independent and nationally representative samples of Swedish children, I compare the university aspirations and expectations between children of immigrants and children of natives. In line with existing findings, I find that children with foreign-born parents have significantly higher aspirations and expectations than their native-majority peers with and without conditioning on school performance, academic potential and friendship networks. I do not find any evidence of a significant immigrant-non-immigrant aspirations-expectations gap; immigrant children's aspirations and expectations are not less aligned than those of their native-majority peers. This result suggests that immigrant-native disparities in school outcomes are not driven by an aspirations-expectations gap. Finally, the results reveal significant gender differences. Native-majority girls with academic potential are, for example, more likely to express an aspirations-expectations gap. Moreover, having only female friends makes one less likely to belong to the aforementioned category.

    The Key Player in Disruptive Behavior: Whom Should We Target to Improve the Classroom Learning Environment? In this paper, I address the question: Who is the individual that exerts the greatest negative influence on the classroom learning environment? To answer this question, I invoke the key player model from network economics and use self-reported friendship data in order to solve the methodological problems associated with identifying and estimating peer effects. I overcome the issue of endogenous group formation by using the control function approach where I simultaneously estimate network formation and outcomes. The results show that the typical key player scores well on language and cognitive ability tests and is not more likely to be a boy than a girl. I also find evidence that removing the key player has a significantly larger effect on aggregate disruptiveness in a network than removing the most disruptive individual, implying that policy aimed at the most active individual could be inadequate.

  • Public defence: 2017-12-15 10:00 rum 207, Stressforskningsinstitutet, Stockholm
    Schiller, Helena
    Stockholm University, Faculty of Social Sciences, Centre for Health Equity Studies (CHESS).
    How to work for a good night's sleep2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stress and sleep problems are common in the working population and cause considerable costs for society. Sleep is the most important part of recovery, and poor sleep has a negative impact on overall functioning, which might have important consequences for both the employee, the employer and society. In order to find strategies to alleviate this contemporary public health concern of stress and poor sleep in the working population, this thesis evaluated interventions performed at the workplace to target these issues.

    The first intervention is a randomized controlled trial of a 25% work time reduction for full-time workers within the public sector in Sweden. Study I evaluated the impact of work time reduction on subjective sleep quality, sleep duration, sleepiness, perceived stress, and bedtime worries. Assessments included diary data from one week at three occasions over 18 months. Study II investigated time-use patterns through activity reporting sheets used during the work time reduction by evaluating the amount of total workload, paid work, non-paid work and recovery activities. Both studies investigated workdays and days off separately as well as the importance of gender, family status and work situation (only Study II). The second randomized controlled intervention of the thesis is a group cognitive behavioral therapy (CBT) intervention at the workplace targeting sleep disturbances among employees within the retail sector in Sweden (Study III). Data were collected through questionnaires, diaries and objective sleep measurement (actigraphy) over a period of ten days before and after the intervention, as well as at a three-month follow up. The study evaluated the effects of the intervention on sleep and explored the moderating effect of burnout-levels at baseline.

    In our studies, an economically fully compensated reduction of work hours for full-time workers lead to long-term positive effects on sleep duration and sleep quality, sleepiness and levels of perceived stress. During this work time reduction, the total workload of both paid and non-paid work was reduced and time spent in recovery activities increased. The results indicate that a more balanced relation between effort and recovery was established. The second intervention, which targets the individual through a group CBT-intervention for insomnia at the workplace, was shown to improve insomnia symptoms in daytime workers who did not suffer from concurrent burnout. Such an intervention could support the individual in handling sleep problems and preventing the development of more severe and chronic sleep disorders, as opposed to interventions aimed at making environmental changes at the workplace. However, the CBT-intervention evaluated within this thesis will need to be further developed in order to be beneficial for more groups of employees. The positive effects of these interventions might be beneficial for public health and help improve employee’s life satisfaction, daily functioning and health development.​

  • Public defence: 2017-12-15 13:00 Vivi Täckholmsalen (Q-salen), NPQ-huset, Stockholm
    Corral López, Alberto
    Stockholm University, Faculty of Science, Department of Zoology.
    The link between brain size, cognitive ability, mate choice and sexual behaviour in the guppy (Poecilia reticulata)2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Competition over access for mates has led to the evolution of many striking examples of morphological traits and behaviour in animals. The rapid development of the sexual selection field in recent decades have dramatically advanced our understanding of what traits make individuals more successful in attracting mates and how preferences for mates evolve over time. However, till now, research in this field has put less emphasis on the mechanisms that underlie variation in mate choice and sexual behaviour. Cognitive processes could potentially be key drivers of individual variation in mating preferences and sexual behaviours and therefore deserve further investigation. In this thesis, I used guppies artificially selected for relative brain size as the model system to study the association between brain size, cognitive ability and various aspects of mate choice. Previous studies in this model system showed that large-brained individuals of both sexes outperformed small-brained individuals in cognitive tests. Here I quantified their sexual behaviours and mating preferences to provide novel empirical data concerning the association between brain size, cognitive ability and sexual selection. In dichotomous choice preference tests based on visual cues, comparisons between large-brained and small-brained guppies showed important differences in their assessment of mate quality. These results are not driven by pre-existing visual biases caused by the artificial selection since further investigation of the visual capacity of these fish detected no differences between large-brained and small-brained individuals in their sensitivity to colour or in their capacity to resolve spatial detail. I also quantified sexual behaviour in male guppies artificially selected for relative brain size and found no difference in the behaviours of large-brained and small-brained males in a single male-single female non-competitive scenario. On the contrary, in a more complex social setting I found a reduction in large-brained males in the rate of courtship towards females and dominance displays towards other males when exposed to different degrees of predation threat and different numbers of male competitors. However, this reduction in behavioural intensity did not result in a lower access to copulation with females for large-brained males. I likewise evaluated female sexual behaviour and found that large-brained females had higher behavioural flexibility such that they decreased their receptiveness towards males more strongly under higher levels of predation threat. Together, these results provide novel empirical evidence that brain size and cognitive ability are tightly linked to mating preferences and sexual behaviours. These findings suggest that brain size and cognitive ability might be important mechanisms behind variation in mating preferences and in sexually selected traits across and within species.

  • Public defence: 2017-12-15 13:00 sal FA32 AlbaNova universitetscentrum, Stockholm
    Bertoli, Gabriele
    Stockholm University, Faculty of Science, Department of Physics.
    Search for Supersymmetry and Large Extra Dimensions with the ATLAS Experiment2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The Large Hadron Collider is the most powerful particle accelerator built to date. It is a proton-proton and heavy ion collider which in 2015 and 2016 operated at an unprecedented center of mass energy of √s = 13 TeV. The Tile Calorimeter is the ATLAS hadronic calorimeter covering the central region of the detector. It is designed to measure hadrons, jets, tau particles and missing energy. In order to accurately be able to properly reconstruct these physical objects a careful description of the electronic noise is required. This thesis presents the work done in updating, monitoring and studying the noise calibration constants used in the processing and identication of hadronic jet in the 2011 data.

    Moreover the results of the searches for compressed supersymmetric squark-neutralino and large extra dimensions models are also presented in this thesis. The present work uses an experimental signature with a high energy hadronic jet and large missing transverse energy later often referred to as monojet signature. The search for supersymmetry is carried out using an integrated luminosity of 3.2 fb-1 recorded by the ATLAS experiment in 2015.

    The search for large extra dimensions presented in this work uses the full 2015 + 2016 dataset of 36.1 fb-1. No signicant excess compared to the Standard Model prediction has been observed on the production of squark pairs with the subsequent decay of the squark in a quark and a neutrino. Exclusion limits are set on squark production as a function of the neutralino mass. Squark masses up to 608 GeV are excluded for a mass difference between the squark and the neutralino of 5 GeV. In the second search for the presence of large extra spatial dimensions in the Arkani-Hamed, Dimopoulos and Dvali model scenario a good agreement between data and Standard Model prediction is observed and exclusion limits are set on the effective Planck scale MD of 7.7 and 4.8 TeV for two and six hypothesized large extra dimensions respectively signicantly improving earlier results.

  • Public defence: 2017-12-15 13:00 Högbomsalen, Geovetenskapens hus, Stockholm
    Marklund, Ellen
    Stockholm University, Faculty of Humanities, Department of Linguistics.
    Perceptual reorganization of vowels: Separating the linguistic and acoustic parts of the mismatch response2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    During the first year of life, infants go from perceiving speech sounds primarily based on their acoustic characteristics, to perceiving speech sounds as belonging to speech sound categories relevant in their native language(s). The transition is apparent in that very young infants typically discriminate both native and non-native speech sound contrasts, whereas older infants show better discrimination for native contrasts and worse or no discrimi­na­tion for non-native contrasts. The rate of this perceptual reorganization depends, among other things, on the salience of the relevant speech sounds within the speech signal. As such, the perceptual reorganization of vowels and lexical tone typically precedes the perceptual reorganization of consonants.

    Perceptual reorganizatoin of speech sounds is often demonstrated by measuring in­fants’ discrimination of specific speech sound contrasts across development. One way of measuring discriminatory ability is to use the mismatch response (MMR). This is a brain response that can be measured using external electroencephalography re­cord­ings. Pre­senting an oddball (deviant) stimulus among a series of standard stimuli elicits a response that, in adults, correlates well with behavioral discrimination. When the two stimuli are speech sounds contrastive in the listeners’ language, the response arguably reflects both acoustic and linguistic processing. In infants, the response is less studied, but has nevertheless already proven useful for studies on the perceptual reorganization of speech sounds.

    The present thesis documents a series of studies with the end game of investigating how amount of speech exposure influences the perceptual reorganization, and whe­ther the learning mechanisms involved in speech sound cate­gory learning is specific to speech or domain-general. In order to be able to compare MMR results across diffe­rent age groups in infancy, a non-speech control condition needed to be devised however, to account for changes in the MMR across development that are attributable to general brain matura­tion rather than language development specifically.

    Findings of studies incorporated in the thesis show that spectrally rotated speech can be used to approximate the acoustic part of the MMR in adults. Subtracting the acoustic part of the MMR from the full MMR thus estimates the part of the MMR that is linked to linguistic, rather than acoustic, processing. The strength of this linguistic part of the MMR in four- and eight-month-old infants is directly related to the daily amount of speech that the infants are exposed to. No evidence of distributional learning of non-speech auditory categories was demonstrated in adults, but the results together with previous research generated hypo­theses for future study.

    In conclusion, the research performed within the scope of this thesis highlight the need of a non-speech control condition for use in developmental speech perception studies using the MMR, demonstrates the viability of one such non-speech control condition, and points toward relevant future research within the topic of speech sound category development.

  • Public defence: 2017-12-15 13:00 William-Olssonsalen, Geovetenskapens hus, Stockholm
    Dahl, Martin
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Natural and human-induced carbon storage variability in seagrass meadows2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Seagrasses are considered highly important CO2 sinks, with the capacity to store substantial quantities of organic carbon in the living biomass and sediments, and thereby acting as a buffer against climate change. In this thesis, I have studied carbon storage variability in temperate and tropical seagrass habitats and identified factors influencing this variation. In addition, as seagrass areas are decreasing worldwide, I have assessed effects of different anthropogenic disturbances on carbon sequestration processes. The result from this thesis showed that there was a large variation in carbon storage within and among temperate, tropical and subtropical regions. The highest organic carbon stocks were found in temperate Zostera marina meadows, which also showed a larger carbon storage variability than the subtropical and tropical seagrass habitats. The tropical and subtropical seagrass meadows had inorganic carbon pools exceeding the organic carbon accumulation, which could potentially weakens the carbon sink function. The variability in organic carbon stocks was generally strongly related to the sediment characteristics of the seagrass habitats. In Z. marina meadows, the strength of the carbon sink function was mainly driven by the settings of the local environment, which in turn indicates that depositional areas will likely have higher organic carbon stocks than more exposed meadows, while in the tropics seagrass biomass was also influencing sedimentary carbon levels. Furthermore, locations with large areas of seagrass were associated with higher carbon storage in tropical and subtropical regions, which could be related to increased accumulation of both autochthonous and allochthonous carbon. In an in situ experiment, impacts on carbon sequestration processes from two types of disturbances (with two levels of intensity) were tested by simulating reduced water quality (by shading) and high grazing pressure (through removal of shoot biomass). At high disturbance intensity, reductions in the net community production and seagrass biomass carbon were observed, which negatively affected carbon sequestration and could impact the sedimentary organic carbon stocks over time. In the treatments with simulated grazing, erosion was also seen, likely due to an increase in near-bed hydrodynamics. When experimentally testing effects of increased current flow on organic carbon suspension in Z. marina sediment, a ten-fold release of organic carbon with higher current flow velocities was measured, which resulted in an increase in the proportion of suspended organic carbon by three times in relation to other sediment particles. Therefore, periods with enhanced hydrodynamic activity could result in a removal of organic carbon and thereby likely reduce the seagrass meadows’ capacity to store carbon. The findings of this thesis add to the emerging picture that there is a large natural variability in seagrasses’ capacity to store carbon, and highlight how human-induced disturbances could negatively affect the carbon sink function in seagrass meadows.

  • Public defence: 2017-12-15 15:00 De Geersalen Geovetenskapens hus, Stockholm
    Cao, Mengyi
    Stockholm University, Faculty of Social Sciences, Department of Economics.
    Labor, Trade and Finance: Essays in Applied Economics2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Essay I: Credit Constraint and College Attendance. 

    This paper shows that housing wealth alleviate credit constraints for potential college attendees by enabling home owners to extract equity from their property and invest it in the education. Using a large US individual-level survey dataset over the 1996-2011 period, I find that one standard deviation increases of housing prices translate into approximately 72,000 more students enrolled in college each year. My results stay significant when I use proxies for aggregate housing demand shocks and for the topological elasticity of housing supply to generate variation in home equity that is assumed to be orthogonal to decision of going to college.

    Essay II: Income Inequality and Trade.

    Does trade with unskilled labor-abundant countries reduce the relative wages of U.S. unskilled labor and consequently cause increased income inequality across industries and regions? Empirical studies in the 1990s found only a modest effect. In this paper, I re-consider the question by using the income inequality measures constructed from Current Population Survey (CPS) data and analyzing the effect of rising Chinese import competition between 1993 and 2007 on US local labor markets. I find that areas which are more exposed to China imports competition have larger changes in income inequality. In my main specification, a $1,000 exogenous decadal rise in a MSA's import exposure per worker leads to a 1.5% increase in the logistic Gini. This re-distributive effect is more profound among non-college educated workers in manufacturing sectors. 

    Essay III: Employee as Creditor: Evidence from Defined Pension Plans.

    In this paper, I show the role of pension plans in shaping the firms' labor market decision. By employing the loan covenants violation and consequently transferring of control rights to creditors, I examine the strategic use of pension underfunding by firms and the resultant wage cuts. I also find that the wage concession is less severe for firms from industry with bigger bargaining power. This study sheds light on how firms strategically renegotiate labor contracts to extract concessions from labor. The evidence suggests that credit contracts between debt-holders and shareholders have spillover effects on non-financial stakeholders. 

  • Public defence: 2017-12-16 13:00 Nordenskiöldsalen Geovetenskapens hus, Stockholm
    Cooper, Andrew
    Stockholm University, Faculty of Humanities, Department of English.
    A unified account of the Old English metrical line2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This study describes the verse design of Old English poetry in terms of modern phonological theory, developing an analysis which allows all OE verse lines to be described in terms of single metrical design.

    Old English poetry is typified by a single type of line of variable length, characterised by four metrical peaks. The variation evident in the lengths of OE metrical units has caused previous models to overgenerate acceptable verse forms or to develop complex typologies of dozens of acceptable forms. In this study, Metrical phonology and Optimality theory are used to highlight some aspects of the relationship between syntax, phonology and verse metrics in determining how sentences and phrases interact with the verse structure to create variation.

    The main part of the study is a metrical model based on the results of a corpus analysis. The corpus is centred on the OE poems Genesis and Andreas, complemented by selected shorter poems. A template of a prototypical line is described based on a verse foot which contains three vocalic moras, and which can vary between 2 and 4 vocalic moras distributed across 1 to 4 syllables. Each standard line is shown to consist of four of these verse feet, leading to a line length which can vary between 8 and 16 vocalic moras. It is shown that the limited variation within the length of the verse foot causes the greater variation in the length of lines. The rare, longer ‘hypermetric’ line is also accounted for with a modified analysis. The study disentangles the verse foot, which is an abstract metrical structure, from the prosodic word, which is a phonological object upon which the verse foot is based, and with which it is often congruent. Separate sets of constraints are elaborated for creating prosodic words in OE, and for fitting them into verse feet and lines. The metrical model developed as a result of this analysis is supported by three smaller focused studies.

    The constraints for creating prosodic words are defended with reference to compounds and derivational nouns, and are supported by a smaller study focusing on the metrical realisation of non-Germanic personal names in OE verse. Names of biblical origin are often longer than the OE prosodic word can accommodate. The supporting study on non-Germanic names demonstrates how long words with no obvious internal morphology in OE are adapted first to OE prosody and then to the verse structure. The solution for the metrical realisation of these names is shown to be patterned on derivational nouns.

    The supporting study on compound numerals describes how phrases longer than a verse are accommodated by the verse design. It is shown that compound numerals, which consist of two or more numeral words (e.g. 777 – seofonhund and seofon and hundseofontig) are habitually rearranged within the text to meet the requirements of verse length and alliteration.

    A further supporting study discusses the difference between the line length constraints controlling OE verse design and those for Old Norse and Old Saxon verse. Previous studies have often conflated these three closely related traditions into a single system. It is shown that despite their common characteristics, the verse design described in this study applies to all OE verse, but not to ON or OS.

  • Public defence: 2017-12-20 10:00 Nordenskiöldsalen, Geovetenskapens hus, Stockholm
    Moberg, Emilie
    Stockholm University, Faculty of Social Sciences, Department of Child and Youth Studies.
    Breakdowns, overlaps and ambivalence: an Actor-network theory study of the Swedish preschool curriculum2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Within the discipline of early childhood education research, the present study will focus on the Swedish preschool curriculum text, using a sociomaterial approach offered by Actor-network theory (ANT). The study adopts ethnographic methods, foremost participant observations in a preschool, to generate knowledge of how the curriculum text comes to act through moments in the everyday preschool work. The doctoral thesis consists of three research papers. Research paper I explores the delayed access to the field through the occurrence of a water leak. Through the focus on the value of breakdowns in ANT, the water leak becomes an empirical event where the researcher is allowed to learn about the mundane objects and practices making a preschool work, such as schedules and lists. Research paper II reports on the case of the curriculum concept of children´s interests (Moberg, 2017). Here, empirical moments are highlighted where the curriculum concept of children´s interests is defined and made to act by children and materialities. Finally, research paper III (Moberg, in press) reports on the case of an evaluation meeting where an evaluation text is to be produced. Here, the curriculum text is highlighted as vulnerable in its inability of embracing pedagogical dilemmas and ambivalence in the preschool everyday work.

  • Public defence: 2017-12-20 13:00 De Geersalen, Geovetenskapens hus, Stockholm
    Lindgren, Jessica
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Small remnant habitats: Important structures in fragmented landscapes2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The world-wide intensification of agriculture has led to a decline in species richness due to land use change, isolation, and fragmentation of natural and semi-natural habitats in agricultural and forestry landscapes. As a consequence, there is a current landscape management focus on the importance of green infrastructure to mitigate biodiversity decline and preserve ecosystem functions e.g. pollination services and pest control. Even though intensification in agriculture has been ongoing for several hundreds of years, remnant habitats from earlier management practices may still be remaining with a surprisingly high plant richness. Preserving these habitats could help conserving plant species richness in agricultural landscapes, as well as other organisms that are dependent on plants for food and shelter.

    In this thesis I focus on two small remnant habitats; midfield islets and borders between managed forest and crop field in southeastern Sweden. In the past, both habitats were included in the grazing system and therefore often still have remnant population of grassland specialist species left today. I have used these two remnant habitats as model habitats to investigate the effect of landscape factors and local factors on species richness of plants, flower morphologies and plants with fleshy fruits. Additively, I analysed the effect of surrounding landscape and local openness on the functions; pollination success, biological pest control of aphids and seed predation on midfield islets.

    One of my studies showed that spatial distribution and size of the habitat affected plant species richness. Larger habitat size and higher connectivity between habitats increased species richness of plants in the habitats. Openness of the habitats was shown to be an important factor to increase species richness and richness of flower morphologies, both on midfield islets and in forest borders. Even though midfield islets had the highest species and morphology richness, both habitat types are needed for habitat complementary as forest borders have more plants with fleshy fruits and a higher richness of plant species that flowers in spring/early summer. It was also shown that a more complex forest border, not just with gaps in the canopy, but also with high variation in tree stem sizes increases plant species richness in the field layer. The conclusion is that by managing small remnant habitats to remain or become more semi-open and complex in their structure, would increase species richness of plants, grassland specialist species, and flower morphologies. It would also increase some ecosystem functions as seed predation and biologic pest control of aphids are more effective close to trees. If both midfield islets and forest borders would be managed to be semi-open, the area and connectivity of semi-open habitat would increase in the agricultural landscape, which may also improve pollination success as the connectivity between populations has a possibility to increase. Grassland specialist species are clearly abundant in the small remnant habitats. As the decline of semi-natural grasslands is causing a decline in grassland specialists’ species, not only plants, I recommend that small remnant habitats are included in conservation and management plans and strategies to improve habitat availability and connectivity for grassland species in agricultural landscapes.

  • Public defence: 2017-12-21 13:00 hörsal 7, hus D, Stockholm
    Kridahl, Linda
    Stockholm University, Faculty of Social Sciences, Department of Sociology.
    Time for Retirement: Studies on how leisure and family associate with retirement timing in Sweden2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Retirement transition is a major life event in later adult life. Its timing is important for older individuals for economic, personal and family reasons, as well as for aging societies contemplating a comprehensive plan for population changes, including sustainability of the labor force, pension system, and welfare services such as eldercare. This thesis explores retirement timing in contemporary Sweden, which serves as an interesting case study because of its aging population, high labor force participation of men and women, universal pension system and generous welfare services. The overarching aim of the thesis is to investigate how relationships in the private sphere associate with retirement timing by focusing on leisure engagement, family relations and intergenerational ties.

    The thesis consists of an introductory chapter and four empirical studies. The purpose of the introductory chapter is to place the four studies in context by focusing on the Swedish population structure, labor force participation and pension system and by highlighting some of the central theories and empirical findings related to retirement transition.

    Study I addresses leisure engagement before retirement and retirement timing, and how engagement in leisure changes after retirement. The study finds that retirement timing varies by both the type of preretirement activity domain and the level of engagement. For instance, occasional or frequent engagement in dance and music postponed retirement compared to no engagement in these activities. The study also finds that patterns of leisure engagement after transition into retirement tend to be a continuation of the corresponding preretirement patterns.

    Study II investigates the association between grandparenthood and retirement timing. The results show that grandparents at different life stages are more likely to retire compared to non-grandparents, but there is also variation among grandparents, and the more complex the family situation, the more likely grandparents are to retire.

    In Study III, the focus shifts to the relationship between survival of elderly parents and retirement timing. The study finds that parental survival is positively linked to retirement timing and that the effects are stronger and more consistent for women thanfor men, in particular when only one parent is still alive. Additionally, women have a higher propensity of retiring in the immediate period after parental death, especially when the father is widowed. In contrast, men have a higher propensity of retiring when either the mother or father has been widowed for some years.

    Study IV examines married couples’ propensity to coordinate retirement. The study finds that the likelihood that spouses will coordinate their retirement decreases as their age difference increases but that age differences have a similar effect on retirement coordination for couples with a larger age difference. The study also finds that coordination is largely gender neutral in opposite-sex couples with age differences, regardless of whether the male is the older spouse.

    The thesis shows that, compared to wealth or health predictors of retirement, factors concerning the private sphere are also most relevant in non-trivial ways to large shares of retirees in Sweden. Increased knowledge of these relationships is important both for individuals’ retirement planning and for decision-makers’ and policy-makers’ planning and organization.

  • Public defence: 2017-12-22 13:00 hörsal 2 hus A, 114 18 Stockholm
    Lars, Ahnland
    Stockholm University, Faculty of Social Sciences, Department of Economic History.
    Financialization in Swedish Capitalism: Debt, inequality and crisis in Sweden, 1900-20132017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation adresses financialization – the increasing role of financial activities in the overall economy – in Sweden in 1900-2013. The focus is on the long run relationships between private debt, asset markets, inequality and financial crisis during this period. In line with established scholarship, the present study finds that changes in bank debt had a positive impact on the probability of financial crisis in Sweden. Functional income distribution between profits and wages was an underlying factor influencing the formation of bank debt levels through its impact on collateral in stock markets. Expenses related to the Swedish welfare state – the size of the public sector, government investment and housing construction – had a long run relationship with the wage share. The welfare state has been an effective counter-measure not just against a high profit share, but also against financialization. Moreover, the dissertation shows that the recent era of financialization in Swedish capitalism is not unique in kind. Rather, recent financialization is very similar to the macroeconomic situation during the early decades of the 20th Century. These findings are consistent with much of heterodox economic theory, in particular the Neo-Marxist approach.