| 1. |
- Lindholm, Karl-Johan, 1970-
(författare)
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Wells of Experience : A pastoral land-use history of Omaheke, Namibia.
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The conventional view on the Kalahari in southern Africa expresses that the area is unsuitable for livestock herding. For this reason, it is argued that livestock herders avoided the Kalahari in the past and were only able to establish themselves in the later half of the twentieth century, when deep-reaching boreholes were introduced in the area. An effect of this concept was that the archaeological record of pastoralists in the Kalahari either was perceived as non-existent or received little attention from scientific enquiry.Based on an archaeological survey in the Kalahari of the northeastern part of Namibia, the purpose of this study is to construct an alternative approach to the archaeology of livestock herding. The aim is to contribute to a better understanding of the areas unrecorded land-use history. I depart from the notion that the main ecological constraint for dryland pastoralism is the availability of dry season water and fodder resources. For this reason, the fundamental basis for a pastoral land-use system is places that contain dry season resources. By reviewing recent ecological research, historical and anthropological accounts and previous archaeological research, I establish a link between livestock herders’ procurement of dry season key resources and the practice of digging wells. The link can be motivated from the pastoral ambition of accumulating livestock and high water requirements in the restrained dry season. On this basis, I suggest that artificial wells are useful indicators of pastoral land use in the Kalahari. The most crucial task for the study is to address the archaeological visibility of pastoral well sites. By a research approach integrating the theoretical understanding of pastoralism and a methodology including ecology, archaeology, history and the knowledge of the people who keep livestock in the region today, the archaeological survey revealed 40 well sites, including nearly 200 well structures that have all been used for watering livestock. However, it would be unfortunate if a study of pastoral wells would solely address the ecological foundation and the archaeological visibility of pastoralism. I suggest that the wells signify the labour of peoples with common or separate histories, with or without own herds, but probably talked about in relation to herds. I will also argue that the wells can be used for tracking and reconstructing a pastoral land-use system that predated the colonial era. Furthermore, the wells can be used to identify changes of the land-use that took place during the twentieth century, which involved that livestock herding was more or less abandoned in large parts of northwestern Kalahari. The study surmises that the critical historical perspective is valuable for development projects and conservationist interventions active in the region, especially in the light of the recent trends in the dryland ecology, which shows a larger appreciation for the indigenous understanding of the management of dryland ecosystems. With modifications, the developed approach can be applicable for land-use historical research elsewhere in southern Africa.
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| 2. |
- Afshar, Sara
(författare)
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Lock-Based Resource Sharing for Real-Time Multiprocessors
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Embedded systems are widely used in the industry and are typically resource constrained, i.e., resources such as processors, I/O devices, shared buffers or shared memory might be limited in the system. Hence, techniques that can enable an efficient usage of processor bandwidths in such systems are of great importance. Locked-based resource sharing protocols are proposed as a solution to overcome resource limitation by allowing the available resources in the system to be safely shared. In recent years, due to a dramatic enhancement in the functionality of systems, a shift from single-core processors to multi-core processors has become inevitable from an industrial perspective to tackle the raised challenges due to increased system complexity. However, the resource sharing protocols are not fully mature for multi-core processors. The two classical multi-core processor resource sharing protocols, spin-based and suspension-based protocols, although providing mutually exclusive access to resources, can introduce long blocking delays to tasks, which may be unacceptable for many industrial applications. In this thesis we enhance the performance of resource sharing protocols for partitioned scheduling, which is the de-facto scheduling standard for industrial real-time multi-core processor systems such as in AUTOSAR, in terms of timing and memory requirements. A new scheduling approach uses a resource efficient hybrid approach combining both partitioned and global scheduling where the partitioned scheduling is used to schedule the major number of tasks in the system. In such a scheduling approach applications with critical task sets use partitioned scheduling to achieve higher level of predictability. Then the unused bandwidth on each core that is remained from partitioning is used to schedule less critical task sets using global scheduling to achieve higher system utilization. These scheduling schema however lacks a proper resource sharing protocol since the existing protocols designed for partitioned and global scheduling cannot be directly applied due to the complex hybrid structure of these scheduling frameworks. In this thesis we propose a resource sharing solution for such a complex structure. Further, we provide the blocking bounds incurred to tasks under the proposed protocols and enhance the schedulability analysis, which is an essential requirement for real-time systems, with the provided blocking bounds.
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| 3. |
- Andersson, Erik, 1984-
(författare)
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PHYSIOLOGICAL AND BIOMECHANICAL FACTORS DETERMINING CROSS-COUNTRY SKIING PERFORMANCE
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cross-country (c.c.) skiing is a complex sport discipline from both physiological and biomechanical perspectives, with varying course topographies that require different proportions of the involved sub-techniques to be utilised. A relatively new event in c.c. skiing is the sprint race, involving four separate heats, each lasting 2-4 min, with diverse demands from distance races associated with longer durations. Therefore, the overall aim of the current thesis has been to examine the biomechanical and physiological factors associated with sprint c.c. skiing performance through novel measurements conducted both in the field (Studies I-III) and the laboratory (Studies IV and V).In Study I sprint skiing velocities and sub-techniques were analysed with a differential global navigation satellite system in combination with video recording. In Studies II and III the effects of an increasing velocity (moderate, high and maximal) on the biomechanics of uphill classical skiing with the diagonal stride (DS) (Study II) and herringbone (HB) (Study III) sub-techniques were examined.In Study I the skiers completed the 1,425 m (2 x 712 m) sprint time trial (STT) in 207 s, at an average velocity of 24.8 km/h, with multiple technique transitions (range: 21-34) between skiing techniques (i.e., the different gears [G2-7]). A pacing strategy involving a fast start followed by a gradual slowing down (i.e., positive pacing) was employed as indicated by the 2.9% faster first than second lap. The slower second lap was primarily related to a slower (12.9%) uphill velocity with a shift from G3 towards a greater use of G2. The maximal oxygen uptake ( O2max) was related to the ability to maintain uphill skiing velocity and the fastest skiers used G3 to a greater extent than G2. In addition, maximal speed over short distances (50 and 20 m) with the G3 and double poling (DP) sub-techniques exerted an important impact on STT performance.Study II demonstrated that during uphill skiing (7.5°) with DS, skiers increased cycle rate and cycle length from moderate to high velocity, while cycle rate increased and cycle length decreased at maximal velocity. Absolute poling, gliding and kick times became gradually shorter with an elevated velocity. The rate of pole and leg force development increased with elevated velocity and the development of leg force in the normal direction was substantially faster during skiing on snow than previous findings for roller skiing, although the peak force was similar in both cases. The fastest skiers applied greater peak leg forces over shorter durations.Study III revealed that when employing the HB technique on a steep uphill slope (15°), the skiers positioned their skis laterally (“V” between 25 to 30°) and planted their poles at a slight lateral angle (8 to 12°), with most of the propulsive force being exerted on the inside forefoot. Of the total propulsive force, 77% was generated by the legs. The cycle rate increased across all three velocities (from 1.20 to 1.60 Hz), while cycle length only increased from moderate to high velocity (from 2.0 to 2.3 m). Finally, the magnitude and rate of leg force generation are important determinants of both DS and HB skiing performance, although the rate is more important in connection with DS, since this sub-technique involves gliding.In Studies IV and V skiers performed pre-tests for determination of gross efficiency (GE), O2max, and Vmax on a treadmill. The main performance test involved four self-paced STTs on a treadmill over a 1,300-m simulated course including three flat (1°) DP sections interspersed with two uphill (7°) DS sections.The modified GE method for estimating anaerobic energy production during skiing on varying terrain employed in Study IV revealed that the relative aerobic and anaerobic energy contributions were 82% and 18%, respectively, during the 232 s of skiing, with an accumulated oxygen (O2) deficit of 45 mL/kg. The STT performance time was largely explained by the GE (53%), followed by O2 (30%) and O2 deficit (15%). Therefore, training strategies designed to reduce energetic cost and improve GE should be examined in greater detail.In Study V metabolic responses and pacing strategies during the four successive STTs were investigated. The first and the last trials were the fastest (both 228 s) and were associated with both a substantially larger and a more rapid anaerobic energy supply, while the average O2 during all four STTs was similar. The individual variation in STT performance was explained primarily (69%) by the variation in O2 deficit. Furthermore, positive pacing was employed throughout all the STTs, but the pacing strategy became more even after the first trial. In addition, considerably higher (~ 30%) metabolic rates were generated on the uphill than on the flat sections of the course, reflecting an irregular production of anaerobic energy. Altogether, a fast start appears important for STT performance and high work rates during uphill skiing may exert a more pronounced impact on skiing performance outdoors, due to the reduction in velocity fluctuations and thereby overall air-drag.
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| 4. |
- de Boer, Hugo J.
(författare)
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Snake Gourds, Parasites and Mother Roasting : Medicinal plants, plant repellents, and Trichosanthes (Cucurbitaceae) in Lao PDR
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background. Traditional plant use was studied in Lao PDR. Research focused on medicinal plant use by the Brou, Saek and Kry ethnic groups, traditional plant repellents against parasitic arthropods and leeches, and the phylogeny and biogeography of the medicinally-important snake gourd genus (Trichosanthes, Cucurbitaceae). Methods. The ethnobiology research used a combination of structured interviews, village surveys, botanical collecting, hydro-distillation, GC-MS analysis, literature studies, and laboratory experiments. The plant systematics research used a combination of morphological studies, molecular biology laboratory work, and phylogenetic, dating and biogeographical analysis. Results. Informants reported the use of close to 100 species to repel arthropods and leeches, many of which have constituents with documented efficacy. Brou, Saek and Kry informants use over 75 plant species for women’s healthcare, mainly during the postpartum period for steam sauna, steam bath, hotbed, mother roasting, medicinal decoctions and infusions, and postpartum diet. A molecular phylogeny of Trichosanthes and Gymnopetalum using a broad sampling of ~60% of their species and 4756 nucleotides of nuclear and plastid DNA shows that Gymnopetalum is nested within Trichosanthes. Fossil-calibrated Bayesian molecular dating of the Trichosanthes phylogeny reveals an early Oligocene origin of the genus, and many of the extant sections originating and diversifying during the Miocene. Biogeographical analysis shows a likely East or South Asian origin of Trichosanthes, with lineages diversifying and spreading throughout Australasia from the early Pliocene to the Pleistocene. Discussion. Traditional plant use in Lao PDR is common and widespread. The presence among the repellent species of economical alternatives to costly synthetic repellents is tenable, and the subject of ongoing studies. Postpartum traditions and medicinal plant use are essential parts of childbirth and postpartum recovery in these ethnic groups, and many other groups in Lao PDR. Efforts to improve maternal healthcare and reduce maternal and infant mortality need to integrate these traditions with modern notions of healthcare to achieve wider adoption. Documenting all possible uses of commonly used medicinal plant species shows that similarity in use between these ethnic groups is relatively low considering that they share, and have shared for many generations, the same environment and resources. A lack of effective cures leads to a process of continuous innovation, where effective cures are shared between cultures, but remedies of only cultural importance, or those under evaluation are culture-specific. The Trichosanthes phylogeny implies the merging of Gymnopetalum into Trichosanthes, and this is done using available names or new combinations. A synopsis of Trichosanthes, the new combinations, and a revision of the species in Australia, are made and presented. Conclusions. Traditional plant use is widespread in Lao PDR, and of significance to many people as a source of primary healthcare and inexpensive repellents. The important medicinal plant genus Trichosanthes includes Gymnopetalum, and has a complex biogeographic history with multiple colonization events of Australasia.
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| 5. |
- Elvers, Ingegerd, 1983-
(författare)
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Replication Fork Stability in Mammalian Cells
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Maintaining replication fork integrity is vital to preserve genomic stability and avoid cancer. Physical DNA damage and altered nucleotide or protein pools represent replication obstacles, generating replicative stress. Numerous cellular responses have evolved to ensure faithful DNA replication despite such challenges. Understanding those responses is essential to understand and prevent or treat replication-associated diseases, such as cancer. Re-priming is a mechanism to allow resumption of DNA synthesis past a fork-stalling lesion. This was recently suggested in yeast and explains the formation of gaps during DNA replication on damaged DNA. Using a combination of assays, we indicate the existence of re-priming also in human cells following UV irradiation. The gap left behind a re-primed fork must be stabilised to avoid replication-associated collapse. Our results show that the checkpoint signalling protein CHK1 is dispensable for stabilisation of replication forks after UV irradiation, despite its role in replication fork progression on UV-damaged DNA. It is not known what proteins are necessary for collapse of an unsealed gap or a stalled fork. We exclude one, previously suggested, endonuclease from this mechanism in UV-irradiated human fibroblasts. We also show that focus formation of repair protein RAD51 is not necessarily associated with cellular sensitivity to agents inducing replicative stress, in rad51d CHO mutant cells. Multiple factors are required for replication fork stability, also under unperturbed conditions. We identify the histone methyltransferase SET8 as an important player in the maintenance of replication fork stability. SET8 is required for replication fork progression, and depletion of SET8 led to the formation of replication-associated DNA damage. In summary, our results increase the knowledge about mechanisms and signalling at replication forks in unperturbed cells and after induction of replicative stress.
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| 6. |
- Evans, Thomas J.
(författare)
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Across landscapes and seascapes : The movement ecology of diving and flying guillemots and gulls during breeding
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Most seabirds breed colonially, at which time they make central-place foraging trips. Parents must collect food both for themselves and for egg production/chick-rearing. How should they forage? I followed five species across two sites in Sweden in the Baltic Sea using GPS and time-depth recorder (TDR) devices, giving information on both flight and diving activity. I use a movement ecology approach, asking questions about which spatiotemporal aspects determine these species’ movement activities and on how species differ in their foraging activity. Further, I test theories of how birds should optimally vary their flight behaviour in response to winds, and of how individual birds collect information on alternative breeding sites, i.e. prospecting.Chick-rearing Common Murre (Uria aalge) from the island of Stora Karlsö (SK; 17.97°E, 57.29°N), foraged most around sunset and sunrise, when they made more frequent and shallower dives compared to at midday. They made longer distance and duration overnight trips where they visited more distant foraging areas than during daytime trips. In a following study I showed that the GPS device deployed had little measurable effect on the Common Murre’s activity, though murres did lose body mass which remains to be explained.During flights returning from foraging sites to their colony at Stora Karlsö, both Common Murre and Lesser Black-backed Gull (Larus fuscus) optimally adjust their airspeeds to minimise their costs of transport, increasing airspeed under headwinds and cross-winds, but reducing airspeed under tailwinds. While the gulls also adjusted their altitude, increasing altitude under tailwinds, thus benefiting from the faster winds higher up, but flying low, where wind is slower, under headwinds and crosswinds; the murres though always fly low, close to the sea surface.Lesser Black-backed Gull are generalist foragers, at Stora Karlsö they feed both on land and at sea. How do they choose between these? Lesser Black-backed Gull were followed with GPS and observations were made at arable fields on nearby Gotland. The gulls foraged most on land early in the breeding season, and during early mornings especially on cool and cloudy days, while they foraged mostly at sea later in the season, and later in the day. They foraged most on fields with short vegetation and low ground-cover, presumably where soil living invertebrates and earthworms are more available.Following four Larus gull species with GPS during the peak breeding period at the Björn Archipelago at Fågelsundet (FS; 17.72°E, 60.63°N), I show using an information reduction and clustering method how different gull species overlap in the types of foraging trip they use, while also using distinct types of foraging trip. Some species used just a couple of types of trip (specialist), while others used several types quite equally (generalists), this variation was also present within species when comparing between individuals.Lesser Black-backed Gull from both Stora Karlsö and Fågelsundet, followed with GPS, made very long-distance return movements away from their colonies, mostly after failed breeding attempts. On the majority of these movements, gulls visited multiple coastal sites, likely prospecting at alternative breeding colonies. The gulls from Fågelsundet travelled furthest, visiting many of the same coastal sites as the Stora Karlsö gulls with no difference between sexes.
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| 7. |
- Gatsinzi, Tom
(författare)
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Regulation of apoptotic processes in neurodegeneration and cancer : In vitro studies on human neuroblastoma cells
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Apoptosis is a highly controlled process of cell death, which is vital for maintenance of all multicellular organisms. Aberrant regulation of apoptosis can give rise to pathological conditions such as neurodegenerative diseases and cancer. Here, we used different human neuroblastoma cell lines to study mechanisms that may be involved in either neurodegeneration or resistance to cancer treatment. First, we have designed and developed tau-anchored FRET sensors (tAFSs) for live cell imaging of local caspase activation. Using these sensors we showed that the Alzheimer’s disease related neurotoxic peptide, amyloid-β, induced a global activation of caspase-3 and -6, but not -9, in neuronally differentiated SH-SY5Y cells. We also investigated the possible role of NF-κB in the resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in different human neuroblastoma cell lines. While N-type SH-SY5Y and IMR32 cells were unaffected, S-type SK-N-AS cells were clearly sensitized to TRAIL by different NF-κB inhibitory agents. However, no correlation between NF-κB inhibition and sensitization to TRAIL could be observed. Instead, induction of reactive oxygen species (ROS) seemed to play a more important role. Furthermore, using tAFSs we also showed that TRAIL resistance in SK-N-AS cells is mainly due to incomplete activation of caspase-3, and could be reversed by different PKC inhibitors.
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| 8. |
- Koh, Niak Sian, 1991-
(författare)
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Safeguarding nature and people : Integrating economics, politics, and human rights to transform biodiversity policies and governance
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- None of the world’s biodiversity goals from the last decade were fully met, as biodiversity losses are occurring at an unprecedented rate. Policies are not always effective; their use may have adverse effects on people and nature. Biodiversity offsets are an example of a policy that can be used to protect and restore biodiversity loss from economic development. Yet, offsets have been criticized for poor ecological outcomes, commodifying nature, and creating social inequality. To address this challenge, we need to learn from the shortcomings of biodiversity policies and governance as new goals are being drafted under the Post-2020 Global Biodiversity Framework.This thesis examines how biodiversity policies can be designed and implemented for effective and equitable outcomes for people and biodiversity. I focus on the design (Paper I) and implementation (Paper II) by examining economic instruments in conservation. I then broaden to the governance landscape by analysing the implementation of policies in national (Paper III) and international regulatory contexts (Paper IV).The 4 papers cover a diversity of cases across the globe at different governance levels. Paper I conducted a policy analysis of offsets from six countries (Australia, England, Germany, Madagascar, South Africa, and the US), through an economic framing of biodiversity trading and institutional arrangements. Paper II reviewed market instruments for conservation, ecotourism and sport hunting in eastern and southern Africa, to analyse whether these instruments can be compatible with new ideas for conservation such as conviviality. Paper III investigated the politics around Mekong hydropower development, through multi-stakeholder interviews and a discourse analysis of the social and environmental impacts of a dam in Laos. Paper IV examined the implementation of the Convention on Biological Diversity (CBD) and how review mechanisms of human rights law can improve compliance.This thesis highlights that a human rights-based approach provides important conceptual and political support for biodiversity governance. It contributes to the science-policy interface with these insights. First, the institutional design and implementation are as important for the outcomes as the type of policy. In economic policies such as offsets, a high involvement of the market does not influence the level of commensurability, but increases the degree of commodification. Second, the contextual factors (politics and power relations) of policies should be acknowledged to address inequality. An institutional design and implementation that ensures meaningful participation and a balance of power is crucial for effective and equitable outcomes. Review mechanisms used in human rights help to navigate power inequities, by ensuring that all rights-holders have a substantial voice.Third, offsets can be designed with different institutional arrangements (state, market, voluntary). If a market approach is chosen with biodiversity trading, effective monitoring and regulation is needed to safeguard biodiversity. Lastly, to foster compliance with policies, management and enforcement approaches can be used in a complementary manner through positive incentives, sunshine methods, and negative incentives. Overall, this thesis provides insights of how to meet our global goals for protecting and restoring biodiversity, while safeguarding people and nature.
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| 9. |
- Mvungi, Esther Francis, 1974-
(författare)
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Seagrasses and Eutrophication : Interactions between seagrass photosynthesis, epiphytes, macroalgae and mussels
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Seagrass meadows are highly productive, ecologically and economically valuable ecosystems. However, increased human activities along the coastal areas leading to processes such as eutrophication have resulted in the rapid loss and deterioration of seagrass ecosystems worldwide. This thesis focuses on the responses of seagrasses to increases in nutrients, subsequent increases in ephemeral algae, and changes in the physical-chemical properties of seawater induced by interaction with other marine biota. Both in situ and laboratory experiments conducted on the tropical seagrasses Cymodocea serrulata and Thalassia hemprichii revealed that increased concentrations of water column nutrients negatively affected seagrass photosynthesis by stimulating the growth of the epiphytic biomass on the seagrass leaves. Interaction between seagrasses and other marine organisms induced different responses in seagrass photosynthesis. Ulva intestinalis negatively affected the photosynthetic performance of the temperate seagrass Zostera marina both by reducing the light and by increasing the pH of the surrounding water. On the other hand, the coexistence of mussels Pinna muricata and seagrass Thalassia hemprichii enhanced the photosynthetic activity of the seagrass, but no effect on the mussels' calcification was recorded. This study demonstrates that seagrass productivity is affected by a multitude of indirect effects induced by nutrient over-enrichment, which act singly or in concert with each other. Understanding the responsive mechanisms involved is imperative to safeguard the ecosystem by providing knowledge and proposing measures to halt nutrient loading and to predict the future performance of seagrasses in response to increasing natural and human perturbations.
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| 10. |
- Nordlander, Thomas, 1985-
(författare)
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Galactic archaeology with metal-poor stars
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The chemical fingerprints of old, metal-poor stars can be used to unravel the events of the newborn Universe and help us understand the properties of the first stars and star clusters. The study of nearby stars to infer properties in the distant past is often referred to as Galactic archaeology. However, the chemical composition of stars cannot be observed directly, but must be inferred by means of spectroscopic modelling. Traditionally, this modelling utilises one-dimensional (1D) stellar atmospheres in hydrostatic and local thermodynamic equilibrium (LTE). Today, we know that departures from LTE (known as NLTE), and differences between 1D model atmospheres and their hydrodynamical three-dimensional (3D) counterparts, become increasingly severe at lower metallicity. The development of NLTE modelling of spectral line formation in 3D atmospheres is still in its infancy, but constitutes a remarkable step forward that has been made possible by parallelised codes and supercomputers. The central theme of this thesis is the application of NLTE analyses to metal-poor stars, to help usher the field of Galactic archaeology forward with important consequences for the nature of the first stellar generations.I present a theoretical NLTE study of aluminium, where I validate the analysis using a set of bright standard stars and provide calculated NLTE effects for a large parameter space. I perform 3D NLTE calculations for the solar spectrum to better constrain the zero-point of the cosmic abundance scale, and find excellent agreement with the meteoritic aluminium abundance.I also present NLTE analyses of metal-poor stars in the globular clusters NGC 6397 and M4. While globular cluster stars were long expected to form from a chemically homogeneous medium, star-to-star abundance variations of light elements indicate multiple epochs of star formation. Massive first-generation stars polluted the interstellar medium from which later generations formed, and I use the observed abundance variations to deduce the properties of the polluting stars. Among the heavier elements, I uncover evolutionary abundance variations that match predictions of stellar evolution models with atomic diffusion. The results indicate that the chemical abundance ratios of unevolved metal-poor stars are affected by gravitational settling, with a bias of the order 25-50 %, increasing towards lower metallicity. This atmospheric depletion mechanism is a probable explanation to why the stellar abundances of lithium fall short of the predictions from standard Big Bang nucleosynthesis.Finally, I apply a 3D NLTE abundance analysis to the red giant SMSS 0313-6708, which is the most iron-deficient star known. The chemical abundance pattern of this star indicates that it formed from gas affected only by Big Bang nucleosynthesis and a single faint supernova. Comparison of the inferred abundance pattern to theoretical predictions leads to constraints on the explosion mechanism and the mass of the metal-free progenitor star.
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