| 21251. |
- Skoglund, Pontus
(författare)
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Reconstructing the Human Past using Ancient and Modern Genomes
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of DNA variation is one of the most promising avenues for learning about the evolutionary and historical past of humans and other species. However, the difficulty associated with obtaining DNA directly from ancient remains have for long kept genomic studies of population history trapped in time; confined to interpreting patterns of modern-day variation without direct historical observations. In this thesis, I outline new approaches for the retrieval, analysis and interpretation of large-scale genomic data from ancient populations, including solutions to overcome problems associated with limited genome coverage, modern-day contamination, temporal differences between samples, and post-mortem DNA damage. I integrate large-scale genomic data sets from ancient remains with modern-day variation to trace the human past; from traits targeted by natural selection in the early ancestors of anatomically modern humans, to their descendants' interbreeding with archaic populations in Eurasia and the spread of agriculture in Europe and Africa. By first reconstructing the earliest population diversification events of early modern humans using a novel large-scale genomic data set from Khoe-San populations in southern Africa, I devise a new approach to search for genomic patterns of selective sweeps in ancestral populations and report evidence for skeletal development as a major target of selection during the emergence of early modern humans. Comparing publicly available genomes from archaic humans, I further find that the distribution of archaic human ancestry in Eurasia is more complex than previously thought. In the first direct genomic study of population structure in prehistoric populations, I demonstrate that individuals associated with farming- and hunter-gatherer complexes in Neolithic Scandinavia were strongly genetically differentiated, and direct comparisons with modern-day populations as well as other prehistoric individuals from Southern Europe suggest that this structure originated from Northward expansion of Neolithic farming populations. Finally, I develop a bioinformatic approach for removing modern-day contamination from large-scale ancient DNA sequencing data, and use this method to reconstruct the complete mitochondrial genome sequence of a Siberian Neandertal that is affected by substantial modern-day contamination.
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| 21252. |
- Skoglösa, Ylva
(författare)
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Pituitary adenylate cyclase activating polypeptide : Expression and neurotrophic activity in the rat brain
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neurotrophic factors play an important role in regulating naturally occurring cell death during neurogenesis. In addition to classical neurotrophic factors, some neurotransmitters and neuropeptides have been shown to exhibit neurotrophic activities. PACAP is a neuropeptide, structurally belonging to the secretin/glucagon/VIP family and one of the most potent activators of adenylate cyclase.This thesis establishes the occurrence and neurotrophic potential of pituitary adenylate cyclaseactivating polypeptide (PACAP) during early CNS and PNS development and after certain injuries to adultrat brain.Employing radioactive in situ hybridisation techniques, PACAP and its high-affinity receptorPRI were shown to be expressed differentially in distinct parts of the embryonic rat brain from E13,suggesting an important function for this peptide during brain development.The functional role of PACAP during neuronal development was investigated, employingembryonic rat cultures. PACAP promoted the survival of mesencephalic dopaminergic neurons to thesame extent as GDNF and increased the number of tyrosine hydroxylase (TH)-immunoreactive neurons,elevated TH protein and enhanced tritiated dopamine uptake in these cultures. Likewise, PACAP protectedthe dopaminergic neurons against 6-OH dopamine toxicity. On embryonic GABAergic neurons, PACAPacted neuromodulatory but had no effect on overall survival. In dissociated cultures of DRG neurons,PACAP's effect on survival was comparable to that of NGF. PACAP furthermore induced calcitoningene-related peptide (CGRP) in DRG explants. These results indicate that PACAP acts as a neurotrophicfactor for developing neurons.Finally, in the adult rat, steady state mRNA levels of PACAP and PRI were altered after injuryin conjunction with neuronal cell death. Intraventricular kainic acid treatment showed the neuropeptide tobe rapidly regulated by exitotoxic mechanisms, whereas traumatic brain injury (TBI) induction wasslower. Pretreatement of the rats with a free radical spin trap, showed the involvement of free radicals inthe regulation of PACAP and PRI mRNA after TBI.
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| 21253. |
- Skoglöv, Erik, 1968-
(författare)
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The Dynamical Spin Vector Evolution of the Asteroids
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dynamical evolution of the spin axis direction due to gravitational and thermal factors is examined. It is found that the spin axis variations generally are regular and relatively small for the bodies in the asteroid main belt. There are also reasons to believe that this is the case for minor objects beyond the main belt. However, it is found that these regular variations are larger when the orbital inclination of the objects is increased. This effect may explain certain features in the spin vector distribution of the main belt asteroids, not possible to explain by collisional factors. The spin vector evolution of the asteroids in the inner solar system, including the Earth- and Mars-crossing objects, is often subjected to strong forces related to frequencies in the orbital evolution. The variations in the spin vector direction are then very large and often subjected to chaos. The larger frequency related obliquity zones of the Mars-crossers are usually regular while the zones of the Earth-Mars-crossers often are of a chaotic nature. The spin vector evolution of asteroids with comet-like orbits is often chaotic regardless of initial obliquity. For the inner solar system asteroids, it is often possible for an initial prograde spin to turn into a retrograde one, or vice versa, due to the frequency related phenomena. Though some spin vector directions seem to be more probable than other ones over time, there are no indications for an evolution towards a more prograde or a more retrograde spin vector distribution.The effects on the spin vector evolution from the thermal Yarkovsky force are examined for objects with radii larger than 50 m. This force will affect the orbital evolution and thus indirectly affect the spin vector evolution. However, it is found that the studied effects are minor as compared to the gravitationally related ones. This is true both for the diurnal and the seasonal variants of the Yarkovsky force.
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| 21254. |
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| 21255. |
- Skoog, Eric, 1986-
(författare)
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Preferences Under Pressure : Conflict, Threat Cues and Willingness to Compromise
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Understanding how preferences are formed is a key question in the social sciences. The ability of agents to interact with each other is a prerequisite for well-functioning societies. Nevertheless, the process whereby the preferences of agents in conflict are formed have often been black boxed, and the literature on the effects of armed conflict on individuals reveals a great variation in terms of outcomes. Sometimes, individuals are willing to cooperate and interact even with former enemies, while sometimes, we see outright refusal to cooperate or interact at all. In this dissertation, I look at the role of threat in driving some of these divergent results. Armed conflict is rife with physical threats to life, limb and property, and there has been much research pointing to the impact of threat on preferences, attitudes and behavior. Research in the field of evolutionary psychology has revealed that threat is not a singular category, but a nuanced phenomenon, where different types of threat may lead to different responses. I argue that by taking a more nuanced approach to threat, drawing on theories from the field of evolutionary psychology, some of the variance in outcomes can be explained. In particular, some commonly observed features of protracted conflicts, such as seemingly indivisible issues and parochialism may be moderated by threat. In the four essays, I address this from both a theoretical and empirical point of view. In Essay I, I illustrate in a formal bargaining setting how threats can lead actors to prefer risky all-or-nothing gambles to division schemes, preventing bargaining solutions to be found. In the second essay (Essay II), I show that willingness to make compromises with members of other groups are not contingent on group affiliation alone, but rather on the expected reciprocity of that group. Furthermore, characteristics of others beyond group can also affect pro-sociality. Based on a threat management perspective, me and my coauthors in Essay III show that non-threatening social categories, such as women or the elderly, are shown higher levels of altruism, also when there individuals are outgroup members. Exposure to violence can even increase altruism across group lines, but only to these non-threatening groups. Finally, in Essay IV, I show that those who experience post-traumatic growth as a result of traumatic events reverse the standard loss aversion people generally display, even showing gain-seeking preferences. Together, these results point to the importance of bringing in a more nuanced conceptualization of the role of threat in the study of peace and conflict. Even in the most brutal and destructive conflicts, humans are able to cooperate, also across group lines. However, for this cooperation to function, managing the threats in conflict is of central importance.
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| 21256. |
- Skoog Svanberg, Agneta, 1958-
(författare)
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The Long and Winding Road : Emotional Reactions during In Vitro Fertilization and Attitudes towards Cryopreserved Embryos and Oocyte Donation
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main aims were to investigate emotional reactions during in vitro fertilization (IVF) treatment among women and men, attitudes of IVF couples towards cryopreserved embryos and public attitudes towards various aspects of oocyte donation in Sweden. Assessments of emotional, physical and social reactions were made on a daily reaction scale and attitudes on the basis of study-specific questionnaires. Both women and men experienced the stages of oocyte retrieval and embryo transfer, as well as the luteal phase, as being particularly stressful and there was a similarity in the type of reaction pattern. Presence of supernumerary embryos for cryopreservation increased the women’s optimism, but did not seem to reduce their level of distress on the day of embryo transfer. One-third of IVF couples chose not to use their cryopreserved embryos. The main reasons among the respondents concerned family planning and too short a legally allowed time of embryo storage. There was strong support for oocyte donation among a subset of the Swedish population. Women were more positive than men towards oocyte donation and to disclosure of the origin to offspring. Factors that might increase the likelihood of women becoming oocyte donors were talking to women with experience of donating oocytes, proximity to the clinic, accessibility of counselling and having children of their own. These results indicate that different approaches to psychological care for women and men may not be warranted during IVF treatment. Contact should be maintained during the cryopreservation period in order to adress the couple’s questions and concerns about the embryos. To increase the donor pool, IVF clinics could provide information about donation to potential donors through the Internet and through experienced donors. The information to donors and recipient couples about different consequences of donation seems to be of great importance.
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| 21257. |
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| 21258. |
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| 21259. |
- Skorup, Paul
(författare)
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Antibacterial Effect and Inflammatory Response in Relation to Antibiotic Treatment of Sepsis
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sepsis defines as life-threatening organ dysfunction caused by a dysregulated host response to infection. The importance of early administration of antibiotics in septic shock is undisputed, but the optimal antibiotic choice remains uncertain. Some national guidelines advocate single β-lactam antibiotic treatment while others recommend a combination of β-lactam and aminoglycoside. This thesis aimed to investigate the anti-bacterial properties and antibiotic-induced inflammatory responses of ß-lactam antibiotic compared with effects of the addition of an aminoglycoside in clinically relevant E. coli porcine intensive care sepsis/septic shock models. We also studied the host's antibacterial capacities in primary and secondary sepsis.In Paper I the addition of an aminoglycoside, in comparison with single β-lactam antibiotic treatment, caused decreased bacterial growth in the liver and greater antibiotic-induced blood killing activity ex vivo. The results thereby constitute possible mechanisms to the previously reported improved survival in the most critically ill sepsis patients receiving the β-lactam/aminoglycoside combination. Also observed in this paper was that individual blood bactericidal capacity may have significant effects on antimicrobial outcome. In Paper II we investigated endotoxin release in vivo after antibiotic treatment in comparison with no treatment. There were no differences, however, antibiotics did increase an inflammatory IL-6 response that was associated with leukocyte activation and pulmonary organ dysfunction. A secondary finding was that the addition of an aminoglycoside to a β-lactam induced trends towards less inflammation compared with β-lactam alone.Paper III compared how challenge with different pre-killed E. coli activates the inflammatory response, resulting in higher cytokine responses, more leucocyte activation and inflammatory capillary leakage after single β-lactam compared with live or heat-killed bacteria. The addition of an aminoglycoside lowered the β-lactam-induced responses.Paper IV demonstrated that animals with secondary sepsis exhibited an attenuated inflammatory response as expected; however, contrary to our hypothesis, the animals’ antibacterial capacities were intact and partly enhanced.We conclude that there are likely several beneficial effects of the addition of an aminoglycoside to a β-lactam therapy regimen in septic shock. Because host antibacterial capacities in secondary sepsis are enhanced, the need for bactericidal antibiotic combinations is not greater in secondary than in primary sepsis.
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| 21260. |
- Skott, Pia, 1967-
(författare)
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Läroplan i rörelse : Det individuella programmet i möte mellan nationell utbildningspolitik och kommunal genomförandepraktik
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines the activities within the Swedish steering system concerning upper secondary school. Sweden has a long history of shared responsibility between the state level of government and the municipalities, dating back to federal decisions concerning the establishment of a compulsory school system. By the early 1990s two parallel changes were taking place within the Swedish educational sector, one concerning the steering system which evolved towards deregulation and decentralization, and the other an extension of the compulsory school. A consequence of the latter change was that in practice upper secondary education became mandatory. The political aim was to realize the vision of “one school for all”. In this study the political vision and the larger question of how to turn it into reality (the differentiation question) is used to show how activities at national as well as the local level of the steering system are formed.
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