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Coming dissertations at TekNat

  • Advanced computations and mass-spectrometric techniques to unravel the dynamics and interactions of proteins

    Author: Joana Costeira-Paulo
    Publication date: 2021-09-16 12:01

    Proteins are an important class of biomolecules, involved in the metabolism, regulation, structure and transport in cells. Unfortunately, many diseases are caused by protein dysfunction. When proteins perform their normal function, they may interact with each other or change their conformation. Protein structure is therefore not static, that is the structure should instead be regarded as dynamic. Further understanding of proteins can in turn lead to new means to manipulate them for therapeutic purposes as well as for basic research.

    To address the challenges posed by the dynamic nature of protein structure and interactions, we combine molecular modelling and mass spectrometric techniques. This has shown to be very powerful, more so than using the techniques individually. With mass spectrometric techniques, proteins can be separated by their mass and shape. This allows for the selection of conformational and binding states. In contrast, computations, namely molecular dynamic simulations, take into account time, which is fundamental for a dynamical analysis.

    In this thesis, we investigated dihydroorotate dehydrogenase (DHODH) and alpha-synuclein (alphaSyn), two drug...

  • Changes in Hydrological Risk Perception and Implications for Disaster Risk Reduction

    Author: Elena Mondino
    Publication date: 2021-09-15 14:46

    Economic losses caused by hydrological extremes, such as floods and droughts, are exacerbating because of increased anthropogenic activities and global environmental changes. Understanding how individuals and communities interact with hydrological extremes thus becomes fundamental to develop effective strategies for disaster risk reduction. Risk perception plays an important role in determining how individuals and communities respond to the occurrence of an extreme event.  This thesis aims at addressing aspects of risk perception that remain largely unknown. They include: i) how flood risk perceptions change over time, ii) the role of previous experiences, and iii) how the perception of flood risk relates to the perception of other natural hazards, such as droughts. The work is based on survey data collected in different study areas – both in Italy and Sweden at the local and national scales – via longitudinal as well as cross-sectional approaches.  

    In relation to the three main objectives, this thesis found that: i) flood risk perceptions evolve differently over time depending on social groups; ii) different types of previous experiences with floods directly influence...

  • Fish population responses to climate change : Causes and consequences

    Author: Matilda L. Andersson
    Publication date: 2021-09-10 14:04

    Lake environments are heterogeneous, and animals show a variety of adaptations to deal with this heterogeneity. Fish often show intraspecific variation in diet, metabolism, and behavior, corresponding to their habitat use. Studies on climate change often ignore this heterogeneity and its importance in determining population-level responses to climate change. 

    This thesis can be broken into two interacting pieces. First, my goal was to assess how water color and temperature changes impact the size, number, and distribution of a common predator, Eurasian perch (Perca fluviatilis), in Swedish lakes. Second, I aimed to examine whether metabolism and resource use differed between lake habitats, corresponding with documented patterns of polymorphism and whether diet differences were maintained along a thermal and water color gradient. By combining the information gleaned from these studies, the overarching goal of my thesis is to better understand how climate change will impact fish populations and how intraspecific variance in these responses will impact ecosystem functioning. 

    I found that warming and browning will likely decrease fish biomass but via different...

  • The role of leptin in zebrafish (Danio rerio) : Novel insights into appetite regulation and reproduction

    Author: Emmanouil Tsakoumis
    Publication date: 2021-09-10 08:52

    The hormone leptin is a peripheral metabolic signal and an important regulator of energy balance. In mammals, leptin acts on the appetite centers in the hypothalamus, causing anorexigenic functions by inhibiting food intake. It is also considered as a link between the nutritional status and the endocrine reproductive axis. However, the actions of leptin in teleosts are not fully understood. This thesis investigated the possible role of leptin in the regulation of appetite and reproduction in teleosts, using a loss of function leptin receptor zebrafish strain (lepr sa12953).

    Under different feeding conditions (normal feeding, 7-day fasting, 2- and 6-hours post refeeding) the transcription of orexigenic and anorexigenic genes was influenced by leptin in the zebrafish brain. Leptin signaling inhibited the transcription of orexigenic genes, during short-term fasting and refeeding, and stimulated the transcription of anorexigenic genes under normal feeding in wild-types, indicating an anorexigenic role of leptin in appetite regulation in zebrafish. Moreover, a leptin-dependent gene regulatory network (GRN), involved in the behavioral and metabolic control of appetite...

  • The exploration and evolution of the avian genomic dark matter

    Author: Valentina Peona
    Publication date: 2021-09-09 13:44

    The development and improvement of genome sequencing technologies in the last decade revolutionised the entire field of biology with genome assemblies of virtually any organism. Despite this tremendous progress, complex genomic regions are systematically missing from genome assemblies and form the so-called "genomic dark matter". The presence of genomic dark matter entails that such regions cannot be fully studied and the effects and/or functions thereof (if any) on the organisms remain hidden. Therefore, it is key to be able to explore those dark genomic corners to fully understand the evolution and physiology of organisms without biasing the interpretations. In this thesis, I contribute to the understanding of the use of new sequencing technologies to assemble complex genomic regions and to investigate the evolution of such regions throughout the avian phylogeny. First, I assessed the best combination of technologies and assembly methods to maximise the resolution of genomic dark matter using genomic data from the paradise crow. This included testing for the presence of repetitive elements, GC-rich regions, G-quadruplex motifs, non-recombining sex chromosomes, and...

  • The Digital Transformation of the Manufacturing Industry : Metamorphic Changes and Value Creation in the Industrial Network

    Author: Vincent Fremont
    Publication date: 2021-09-09 11:32

    The Industry 4.0 trend poses many challenges for the manufacturing industry and societies generally. The trend presents new challenges and opportunities related to industrial competitiveness and sustainability, as industrial firms adopt digital technologies to change how they interact and exchange data across their industrial network.  The introduction of digital technologies is resulting in a complex technological and organizational structural change process called digital transformation, which sees interfirm interactions, capabilities and identities changed across the industrial network. The digital transformation change process has remained relatively ill-defined, as most industries are yet to show the full potential of successful digital transformation. Firms within the manufacturing industry still have difficulties grasping the impact and costs of Industry 4.0 and of the digital transformation process. The prevailing assumption in the literature is that industries will achieve value creation simply by engaging with digital technologies, either in higher revenues, profitability or both if they are successful. The change process affects all aspects of industrial network,...

  • Structural properties of problems in sequential testing and detection

    Author: Yuqiong Wang
    Publication date: 2021-09-09 08:41
  • Anti-Ageing Strategies : How to avoid failure in sodium-ion batteries

    Author: Le Anh Ma
    Publication date: 2021-09-02 14:06

    In order to move away from fossil fuels, batteries are one of the most important technologies to store energy from renewable sources. The rapid demands of battery applications put pressure on supply chains of raw materials, such as lithium, nickel, copper, aluminium and cobalt. There is a concern about the availability of such elements in the future. Sodium-ion batteries based on naturally abundant elements have become an attractive alternative to lithium-ion batteries due to their potential to reduce the cost and to improve the sustainability of batteries. A low electrochemical cycling stability of these Na-ion batteries can hinder long-term implementation in large-scale applications. It is necessary to understand what can lead to ageing and electrochemical cycling failure in sodium-ion batteries and how such detrimental side-reactions can be prevented. Compared to lithium-ion batteries, the research on sodium-ion batteries is not as mature yet.

    This thesis work sheds light on the ageing mechanisms at the electrode/electrolyte interfaces and in the bulk of electrode materials with the help of a variety of spectroscopic and electrochemical methods. The electrochemical...

  • Adaptation and plasticity within and across generations

    Author: Zuzana Sekajova
    Publication date: 2021-08-31 10:20

    The environment is seldom stable but often changes from one state to another and in order to survive and reproduce organisms need to respond to those changes. If the change is fast, genetic adaptations may not evolve quickly enough and organisms must adopt other strategies, such as phenotypic plasticity. As there are different types of environmental variations, the optimal type of plasticity also differs. However, plasticity is not always adaptive but can sometimes result in phenotype further away from the optimum. In the thesis I investigate how different types of environmental variation influence adaptation and phenotypic plasticity. I used experimental evolution approaches (Paper I, II) and RNA interference, (Paper III) in Caenorhabditis remanei (Paper I, II) and Caenorhabditis elegans (Paper III). In Paper IV I tested whether trade-offs with lifespan are caused by energy allocation, and if there are trans-generational fitness effects. In Paper I I show that the evolution of life histories, indeed, depends on whether organisms evolve in stable, fluctuating...

  • Wave energy converter: hydrodynamics and control

    Author: Tatiana Potapenko
    Publication date: 2021-08-26 13:30

    Waves, just like wind and solar radiation, is a widely available renewable energy source. Waves are created when winds move across the sea surface. The estimated potential of wave energy is abundant, but the commercial harvesting technologies are still in their infancy. There are different wave energy converter designs, one of which is developed at Uppsala University and is based on a permanent magnet linear generator. A semi-submerged buoy on the water surface absorbs the energy of the wave and converts the mechanical energy into electricity with a direct drive linear generator.

    One of the main goals in wave energy research is to enhance the absorbed power for a single device and multiple devices in wave energy parks. The energy harvest can be increased in different ways: by optimizing the buoy, the generator, and/or by implementing control strategies. To assess the best optimization strategies numerical modeling is an inexpensive tool, aimed to predict the complex behavior of the system. 

    This licentiate thesis focuses on the study of wave energy converters in irregular waves for testing sites, such as in Lysekil (Sweden) and Wave Hub (UK). The numerical model is...