1 - 16 of 16
rss atomLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
  • Public defence: 2019-04-24 13:00 Gröjersalen, hus 3, Kräftriket, Stockholm
    Félez Viñas, Ester
    Stockholm University, Faculty of Social Sciences, Stockholm Business School.
    Changing the Rules of the Game: A Market Microstructure Perspective on the Effects of Regulating Financial Markets2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation contains four articles that examine the effects brought about by the implementation of new regulations and changes in the trading landscape on different facets of market quality and integrity.

    Article I studies how the fragmentation of equity markets affects the speed of recovery of the market, both under normal market conditions and in times of stress. The results show that fragmentation increases the average ability of the market to converge towards its long-run liquidity levels by shortening the duration of liquidity deviations. In times of stress, fragmentation also speeds up the replenishment of the limit order book and its ability to recover from the moments of stress.

    Article II examines the impact of introducing short selling restrictions on the speed of recovery of the market and commonality in liquidity. The findings indicate that short selling bans contribute to lowering the risk of financial contagion by decreasing the commonality in liquidity levels of banned securities. However, the restrictions also significantly hamper the ability of banned stocks to recover from transitory liquidity deviations.

    Article III exploits the change in closing mechanism of 43 exchanges around the world to analyse the effects of batch facilities on liquidity, price efficiency, and market integrity. The results support the idea that batch facilities improve market quality, that auction design is important in explaining auction performance, and that the effects depend on the level of development of the market and the liquidity of the stock.

    Article IV investigates whether volatility extensions in closing auctions improve the efficiency of closing prices. The findings confirm that the introduction of a volatility extension enhances price efficiency by reducing transitory closing price volatility. The results also suggest that the improvement in price efficiency is due to enhanced market integrity and to greater investor trust in the auction mechanism.

  • Public defence: 2019-04-25 13:00 FB42, AlbaNova universitetscentrum, Stockholm
    Giacomozzi, Linda
    Stockholm University, Faculty of Science, Department of Physics.
    Collision- and photon-induced dynamics of complex molecular ions in the gas phase2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, I report experiments probing collision- and photon-induced molecular dynamics in the gas phase. Excited molecules formed in such interactions may relax by emitting electrons or photons, isomerization or fragmentation. For complex molecular systems, these processes typically occur on timescales exceeding picoseconds following statistical redistribution of the excitation energy across the internal degrees of freedom. However, energy transfer to molecules through ion/atom impact may in some cases lead to prompt atom knockout in Rutherford-type scattering processes on much faster timescales. Another example of such a non-statistical process is photon-induced excited-state proton transfer, a structural rearrangement occurring on the femtosecond timescale.

    In this work, I investigate the competition between statistical and non-statistical fragmentation processes for a range of molecules colliding with He at center-of-mass energies in the sub-keV range. I show that heavy atom knockout is an important process for systems containing aromatic rings such as Polycyclic Aromatic Hydrocarbons (PAHs) or porphyrins, while statistical fragmentation processes dominate for less stable and/or smaller systems such as adenine or hydrogenated PAHs. Furthermore, I present the first measurements of the threshold energies for prompt single atom knockout from isolated molecules. The experimental results are interpreted with the aid of Molecular Dynamics (MD) simulations which allow us to extract the energy deposited into the system during a collision, knockout cross sections, fragmentation pathways and the structures of the fragments. The results presented in this work may be important for understanding the response of complex molecules to energetic processes in e.g. astrophysical environments.

    Furthermore, I present the results of photodissociation and luminescence experiments probing flavin mono-anions in the gas phase. These are compared against calculations and previously measured spectra in solution. The discrepancies between the present results and the theoretical values suggest that more consideration of the vibronic structure is needed to model the photoabsorption and emission in flavins. Finally, I present the results of photoisomerisation experiments of flavin di-anions where two different isomers have been found and I discuss the proton transfer mechanisms which govern the structural changes.

  • Public defence: 2019-04-26 10:00 David Magnussonsalen (U31), Stockholm
    Azad, Azadé
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Characteristics of adolescent females with limited delinquency: Developmental challenges in relation to family, peers and education2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Adolescence is a developmental period marked with several changes in a young person’s life. Most adolescents who commit crimes desist over time. Despite this, research has mainly focused on those with extensive and long-term delinquency, including mostly males. Young females with limited delinquency are thus an under-researched group. The overall aim of the thesis was to explore the characteristics of young females with limited delinquency, and relate these features to developmental aspects of adolescence. Further, the objective was to study potential challenges they experience, in connection to family, peers and school. All four studies were based on data from young females sentenced to youth service. Studies 1 and 2 include all (N=144) females convicted in a major city in Sweden during 2007–2012. The data collected through self-reports based on ADAD interviews at the beginning of youth service in Study 1 was further complemented and followed up in Study 2 with registry data on education and recidivism 24 months after starting their sentence. Studies 3 and 4 were based on in-depth interviews with nine adolescent females who started their sentence between 2012–2013 in one of two major cities in Sweden. The results confirmed the assumption that this group of offenders displayed limited delinquency. Their self-reports in Study 1 showed low involvement in crimes during twelve months prior to youth service, which was similar to the reporting of a reference group of females in general. Displaying limited delinquency was supported by registry data in Study 2, showing that the majority of the females did not reoffend within two years after being sentenced, as measured by suspicion and conviction rates. However, they did show high educational deficits. This was evident both by high levels of self-reported school problems in Study 1 and final grade point in compulsory and upper secondary school in Study 2. Their educational attainment was lower than adolescent females in general, irrespective of whether they reoffended or not. These findings suggest that although the females were limited in their delinquency, their low levels of education could still put them at risk for suboptimal development. In the interviews, participants ascribed particular importance to peers and family when describing their delinquency. The narratives illustrated how the process of delinquency as it concerned interpersonal relations involved mutually influential exchanges, both contributing to as well as being affected by the delinquency. As such, delinquency was, in Study 3, portrayed as a way to socialize, where delinquent peers were considered important for committing crimes, and pro-social peers for desisting. Likewise, family relations in Study 4 were given a prominent role in the entire process. Accordingly, delinquency was described as a consequence of the relations to the family, where these were negatively as well as positively affected by the crimes. The collective results indicate that committing crimes for the females may be viewed as part of normative development, in which the quest for independence and establishing ones’ identity can contribute to these behaviors. Practical implications for work with young female offenders are also discussed.

  • Public defence: 2019-04-26 13:00 FB52, AlbaNova universitetscentrum, Stockholm
    Libbrecht, Tine
    Stockholm University, Faculty of Science, Department of Astronomy.
    The diagnostic potential of the He I D3 spectral line in the solar atmosphere2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The research question of my PhD is in a way a simple one: what can observations of the He I Dline teach us about the solar chromosphere? This optical spectral line at 5876 Å is generally formed in the upper chromosphere, and is sensitive to the local magnetic field. The He I D3 line is also indirectly sensitive to heating of the transition region and corona, since it is resulting from a transition that occurs between levels in the triplet system of neutral helium. These levels are generally populated via an ionization-recombination mechanism under the influence of EUV radiation originating in the transition region and corona.

    The He I D3 line was used as a flare diagnostic in the seventies and in the subsequent decades also to measure magnetic fields in prominences. However, due to the poor spatial resolution and low signal-to-noise of that data, almost exclusively off-limb targets have been studied. The on-disk absorption of He I D3 is very weak and localized. Recent instrumental developments allow for the acquisition of high spatial resolution on-disk spectroscopic and spectro-polarimetric data of He I D3 with different instruments at the SST, opening the possibility of studying all types of targets in the chromosphere in a new light. During my PhD, I have focused on the study of reconnection targets via high-resolution observations of He I D3 with TRIPPEL and CRISP at the SST, in co-observation with space-borne instruments. Subsequently, a theoretical study has aimed at in-depth understanding of He I D3 line formation in small-scale reconnection events.

    The data which I have obtained and analyzed during my PhD has provided new insights in Ellerman bombs and flares. Our He I D3 observations have suggested that the temperature of Ellerman Bombs is higher than 2×104 K based on the discovery of helium emission signatures in these events. This result is unexpected, since previous modeling in the literature estimates the temperatures of Ellerman Bombs below 104 K. Subsequently, 3D non-LTE radiative transfer calculations have revealed the detailed physical mechanisms to generate He I D3 emission in these events. The calculations also confirmed that temperatures between 2×104 - 106 K are required to populate the helium triplet levels.

    In the context of flares, we measured strong downflows in the chromosphere via He I D3, revealing detailed dynamics in the deep atmosphere during a flare. Spectro-polarimetry was used to measure the magnetic field during a flare and to propose its magnetic topology. In conclusion, the He I D3 line is an excellent probe for reconnection targets in the solar atmosphere. Detailed dynamics as well as the magnetic field configuration can be derived using the line. Our findings encourage the use of the He I D3 spectral line as a diagnostic for the chromosphere and open up a range of applications that is yet to be exploited.

  • Public defence: 2019-04-26 13:00 föreläsningssalen, Filmhuset, Stockholm
    Rozenkrantz, Jonathan
    Stockholm University, Faculty of Humanities, Department of Media Studies.
    Electronic Labyrinths: An Archaeology of Videographic Cinema2019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This study scans six decades of film history in search for video images, the imaginaries within which they are framed, and (taking cues from the archaeological methods of Friedrich Kittler and Michel Foucault) their technical, historical, and institutional conditions of existence. The British experimental science fiction film Anti-Clock (Jane Arden and Jack Bond, 1979) revolves around a video device with the capacity to confront subjects with their own repressed memory images. While being fictional, these “memory monitors” have real conditions of existence: the emergence of video therapy and surveillance practices, conceptions of video as a recording medium, and the video processing allowing for this imaginary medium’s cinematic treatment. Framing such films as videographic cinema, this study provides a mapping and tracking of works such as Anti-Clock. From prospective imaginaries of surveillance and control to retrospective ones concerned with memory and history, the two-part dissertation tracks an epistemic shift occurring between videographic cinema’s emergent phase conditioned by video as a medium for live transmission (1950s-1980s), and its remanent phase in which the video images and imaginaries become reconditioned by the reconception of video as a recording technology (1970s-2010s).

    Chapter 1 looks at the emergence of videographic cinema through 1960s science fiction films and political thrillers in which the electronic image came to connote imminent futures of surveillance and control. Chapter 2 studies films that responded to the perceived threats of broadcast TV by imagining more or less outrageous reality TV formats. Drawing on research published by a forgotten avant-garde of psychiatrists, Chapter 3 shows how video in the 1960s gave rise to a utopian belief in self-confrontation techniques whose progressive promises were complicated by explicit overlaps between video therapy and surveillance practices. Video self-confrontation techniques also inform Chapter 4, which tracks the emergence of the videographic psyche (based on an analogy between videographic and mental images) as it was invented/discovered by 1970s artists, therapists, and filmmakers – soon to crystallise into the conception of video as a means for confronting subjects with their own repressed memories. Chapter 5 zooms out to map a larger post-millennial media landscape in which the obsolescence of analogue video granted a nostalgic appeal to its particular noisy aesthetics, fusing the cultural connotations of a certain retro “VHS style” with the material conditions of magnetic recording. Continuing the mapping of analogue video in the digital age, Chapter 6 zooms in on a selection of recent films that excavate obsolete video formats to scrutinise historical events and the media conditions of their description. Having started as an archaeology of videographic cinema, the dissertation thus ends by considering videographic cinema itself as a form of archaeology.

    The full text will be freely available from 2020-04-27 09:00
  • Public defence: 2019-05-03 10:00 Lilla hörsalen, NOD-huset, Kista
    Fasth, Tobias
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Decision Analysis in Situations with Conflicting Interests2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Decision problems in participatory decision making involve multiple stakeholders, who often have conflicting preferences concerning the actions under consideration. Decision problems such as these can be structured as multi-criteria problems, which enables the actions to be evaluated in terms of more than one single criterion. In these situations, the complexity of the problem increases when the objective is to select a portfolio of actions. Another aspect to take into consideration is that the choice of actions often has a long-term impact on the lives of the stakeholders. It is therefore not surprising that these problems often are sources of costly and time-consuming conflicts.

    This thesis presents artifacts in the form of methods and applications aiding the decision maker in participatory decision making problems in highlighting stakeholder conflict. The artifacts are DANCE, XPLOR, POLA, and SENS. DANCE is a framework of methods that are used to elicit preferences, and to measure and analyze conflicts between and within stakeholder groups regarding the performance of an action. The framework uses three novel artifacts: i) CAR-CE a method for preference elicitation, ii) two indices, one for measuring the conflict within one stakeholder group, one for measuring the conflict between two stakeholder groups, and iii) an approach to portfolio optimisation and robustness analysis. XPLOR is a web-application that is used to explore and visualise stakeholder conflicts. POLA is a web-application for evaluating commercial development policy in cooperation with key stakeholders. The last artifact, SENSE, is a method for sensitivity analysis of portfolios.

    The artifact development followed the design science methodology, where the aim of the artifact is to solve a practical problem and where, in this case, the artifacts were evaluated against a set of requirements. The preference elicitation method, CAR-CE, was implemented in a web-questionnaire and was used in a real-world survey in cooperation with Upplands Väsby municipality. The elicited preferences were used in illustrative scenarios to demonstrate both the DANCE framework and XPLOR. POLA was demonstrated in three examples based on results from workshops that were conducted together with the municipalities of Norrköping, Katrineholm and Filipstad. Altogether, these artifacts support decision makers in modeling and analyzing decision problems, with the purpose of avoiding future costly and time-consuming conflicts in land use planning.

  • Public defence: 2019-05-03 10:00 Vivi Täckholmsalen (Q-salen), NPQ-Huset, Stockholm
    Staveley, Thomas
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Fish in the coastal seascape: exploring ecological processes and connectivity for conservation of temperate fish communities2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The need to understand patterns and processes in the marine environment has never been so profound as today, particularly as anthropogenic pressures upon coastal regions are drastically affecting habitats and species across a vast range. One approach to further understand these patterns and processes is through the use of seascape ecology methods. Pertinently, fish are ideal candidates to use in many seascape ecological studies due to their mobility and potential to connect a multitude of patches and habitats throughout their life cycle. They also serve as fundamental components in coastal food webs and are of economic benefit. This thesis strives to answer how fish assemblages are affected by ecological and environmental patterns and changes in temperate seascapes throughout the Swedish Skagerrak and the Baltic Sea. 

    Initially, the spatial arrangement of benthic habitat patches in coastal Skagerrak was investigated in relation to the fish community inhabiting seagrass meadows. Seascape structure and complexity was shown to create optimal or sub-optimal areas for certain parts of the fish community. For instance, simpler seascapes (e.g. less habitat patches and edges) were found to have a higher density of juvenile fish, while wrasse densities were related to more complex seascapes. This offers insights into the consequences of spatial patterning in the marine environment and possible effects of habitat loss in the ecosystem (paper I). Through surveying fish assemblages in common, shallow-water habitats, the more structurally complex habitats, i.e. seagrass and macroalgae, were found to harbour a greater fish abundance compared to the less complex unvegetated soft bottoms. However, all three habitats were deemed important for their role in supporting juvenile fish species, thus suggesting that embayments in this environment might function as seascape nurseries (paper II). The importance of connectivity of a marine predator was discovered using acoustic telemetry and network analysis. This study demonstrated that sea surface temperature was of major importance for Atlantic cod movement dynamics within a fjord system as well as revealing the significance of localised connectivity at varying spatial and temporal scales (paper III). Finally, spatial pattern relationships and fish assemblages were explored in Baltic seagrass meadows. Fish assemblages were dominated by meso-predators (i.e. three-spined stickleback) both during summer and autumn, with a noticeable lack of larger piscivorous species throughout both seasons. Correlative analysis showed that fish densities were influenced by seagrass habitat structure (negatively), area of bare sediment (negatively) and habitat patch diversity (positively) (paper IV).  

    This thesis has lifted a central role in addressing important seascape ecology questions and tools in the temperate marine environment. Specifically, it highlights the importance of analysing patterns and processes at multiple scales to gain a more comprehensive understanding of the relationships between fish and their environments, which is relevant for marine spatial planning and conservation. 

  • Public defence: 2019-05-03 13:00 Hörsal 12, hus F, Stockholm
    Malmén, Stina
    Stockholm University, Faculty of Social Sciences, Department of Economic History and International Relations.
    I företagshistoriens marginaler: Familj, fostran och fortlevnad i sekelskiftets dynastier2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The dissertation addresses the question of power structures in corporate families. Two leading Swedish corporate dynasties during the pre-first world war era are examined from an intersectional perspective: the Ekman and the Wallenberg families. The Wallenberg family is still situated in the absolute top of Swedish business community, while the Ekman family has lost its position as a leading dynasty.Traditionally, research about family firms has been shaped by the understanding of a public/private dichotomy. The focus has often been on formal processes and arenas for corporate management in the “public sphere”. Another focus area in studies about family businesses is the matter of succession of leadership. This dissertation draws on critical research that has put the public/private dichotomy into question regarding the everyday operation of family businesses. In line with this research, the present study argues for a more inclusive understanding of this type of corporation, where the “private sphere” may also be considered an arena for management in the family firm. An important aspect in building and developing a dynasty is biological reproduction and the upbringing of future successors in order to secure continuity. Furthermore, this study seeks to deepen such an understanding by examining the significance of social reproduction for management and continuity in these families.Three of the articles investigate the interplay between family and business by highlighting the importance of social reproduction in order to establish successful management and continuity. Here, the role of the children and the spouse of the corporate owners proves to be of great significance. The fourth article problematizes the role of archives in knowledge production regarding family firms and argues for a greater awareness about what narratives are enabled by these archives.

  • Public defence: 2019-05-04 13:00 Auditorium (215), Manne Siegbahnhusen, Stockholm
    Rothmund, Irene Velten
    Stockholm University, Faculty of Humanities, Department of Culture and Aesthetics.
    Å gjøre dansen til sin: Bachelorstudenters levde erfaringer i moderne- og samtidsdans2019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The aim of this PhD-thesis is to explore bachelor students' lived experiences with different traditions in modern- and contemporary dance in a vocational dance education. The project is informed by Hans- Georg Gadamer's philosophical hermeneutics and Max van Manen's hermeneutic phenomenological method. The material consists of logbooks and interviews collected over a longer timespan from 11 students at the Norwegian University College of Dance. The researcher herself is a dance teacher at the same institution. The thesis develops knowledge about processes in a vocational education in dance, upon which there is little existing research, by making the students' voices heard. With an emphasis on the students' experiences in their daily dance training, the thesis also sheds light on how modern dance, postmodern dance and contemporary dance can be understood as partly separate traditions, with different views on dance technique, the body and aesthetic ideals.

    The material is organised into four main areas, which is interpreted in four chapters: 1) Traditions in modern- and contemporary dance, 2) Learning in modern- and contemporary dance, 3) Being present in the body and in the dance, and 4) Transformation – becoming a dancer and dance teacher in modern- and contemporary dance. Each chapter has its own theoretical lens, of these the most central are: Gadamer's understanding of tradition, play and Bildung, Peter Jarvis' theory of human learning and some selected themes from Maurice Merleau-Ponty's phenomenology.

    The contributions of the thesis are connected to 10 main themes that elucidate central characteristics of the students' lived experiences during their education. The last main theme, to make the dance one's own, characterises the students' transformation during the education, and is also central to the other main themes. The research identifies three levels in how the students make the dance their own: The first level, incorporating movements, technique and style, details the students' daily practices of learning dance. The second level, feeling ownership of the dance, the body and one's own expertise, concerns a deeper change over time where the students develop their own bodily knowledge in dance. The third level, making a repertory of practices one's own, is focused on the change in the students' relation to traditions in modern- and contemporary dance, and how they incorporate parts of the contemporary dance tradition into their own lives and self-understanding.

  • Public defence: 2019-05-06 10:00 Ahlmannsalen, Geovetenskapens hus, Stockholm
    Reite, Torun
    Stockholm University, Faculty of Humanities, Department of Romance Studies and Classics.
    Discursos fronteiriços de jovens moçambicanos: A linguagem, as ideologias e as subjetividades na colonialidade contemporânea2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Why are we talking about coloniality in postcolonial times? And what does language have to do with it? In addressing these two broad questions, this thesis sets out to provide empirically well-grounded reflections focusing: First, on how young Mozambicans’ linguistic repertoires and discursive practices relate to their sense of being in the world. And second, on how their perceptions resonate with recent sociolinguistic debates about the different roles language and ideologies play in constructing and reproducing conditions of contemporary coloniality. The role of postcolonial Portuguese is particularly highlighted. The introduction provides a critical, decolonial and epistemic reflexion that brings together four seemingly disparate studies. Moreover, it offers an invitation to critically reflect on discourses, ideologies and valuations that are carried in and on our individual and collective historical bodies and minds and are reproduced through different manifestations of what I call ‘discursive re(b)orderings’. Study I, explores how Portuguese spoken in Maputo has changed after independence and underpins the inquiry into the ‘construct’ of linguistic boundaries and its relation to ideas of language purity and how these ideologically laden notions impact knowledge production and perceived and lived mobilities in the ‘postcolony’. Study II, displays ‘languaging’ practices of young Mozambicans and their strategic orientations in their social-spatial deployment of linguistic resources, and explores ‘translanguaging’ as discursive space production. Study III, brings Frantz Fanon into the study of sociolinguistics of subjectivity and explores the reflexes of the ‘other’ in the constitution of the self of young Mozambicans, suggesting that intersubjectivity holds the promise of disentangling Fanon´s notion of ‘sociogenese’. Study IV brings Pierre Bourdieu´s Distinction (1984) into the ‘postcolony’ by emulating his methodology through multilevel big picture data, combining quantitative and qualitative data and analyses with approaches inspired by ethnography to look at ‘positions and dispositions’ of young Mozambicans across fields and markets. Theoretically, the thesis brings Bourdieu and Fanon together, and shows how nexus concepts, intersubjectivity and the historical bodies and minds represent promising avenues to the understanding of language in coloniality. Two nexus concepts, the habitus and the sociogenese, are adopted and complement each other. By mixing methodologies, the studies combined, manage to capture the complexities in the multi-layered and often subtle ways discursive bordering constructs and reproduces contemporary coloniality. Empirically, taken together, the four studies show how ideologies, the ‘constructs’ surrounding language and the symbolic value of Portuguese are taken up in language and discourses and in speakers’ strategic deployment of linguistic resources across fields and marketplaces in the ‘postcolony’. Moreover, it shows how all forms of capital: epistemic, economic, educational, linguistic and symbolic are reconfigured and revaluated. Nevertheless, mobility is contained, and socioeconomic inequalities are mirrored in sociolinguistic inequalities and even in material urban space to the effect of perpetuating conditions of contemporary coloniality.

  • Public defence: 2019-05-10 10:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Björck, Markus
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Regulation of proton-coupled electron transfer in cytochrome c oxidase: The role of membrane potential, proton pathways and ATP2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cytochrome c oxidase (CytcO) is the final electron acceptor of the respiratory chain. In this chain a current of electrons, derived from degradation of nutrients, along with protons, are used to reduce oxygen to water. The reaction is exergonic and the excess energy is used to pump protons across the membrane. This proton-coupled electron transfer is regulated, for example, by the membrane potential, the composition of the membrane and the ATP/ADP concentrations. 

    Here, we have investigated the mechanism of this regulation. Specifically, we investigated ligand binding to CytcO in mitochondria, which provides mechanistic information about CytcO in its native environment. In addition to CytcO, a water soluble protein, flavohemoglobin (yHb) was found to bind CO and we found that it is localized in the intermembrane space (IMS). We also extracted CytcO from mitochondria without detergent using the styrene maleic acid (SMA) co-polymer. We could show that the SMA-extracted CytcO behaved similarly in its reaction with O2 and CO as CytcO in mitochondria.

    In mitochondria and bacterial membranes CytcO transports charges against a transmembrane electrochemical gradient. We induced a membrane potential across sub-mitochondrial particles (SMPs) by addition of ATP and measured single CytcO turnover. Our results indicate that proton transfer, but not electron transfer, across the membrane is affected by the membrane potential.

    In yeast CytcO subunit Cox13 has been shown to play a role in ATP/ADP binding to regulate activity. We have solved the structure of Cox13 using NMR and identified the residues that constitute the ATP-binding site, which is located at the C-terminus.

    Finally we showed that the main proton-transfer pathways in yeast CytcO function similarly to their bacterial counterparts and that the proposed H-pathway, absent in bacteria, is not responsible for proton translocation in mitochondrial CytcO from S. cerevisiae.

  • Public defence: 2019-05-10 13:00 FP41, hus 1, AlbaNova universitetscentrum, Stockholm
    Anderson, Emma K.
    Stockholm University, Faculty of Science, Department of Physics.
    DESIREE: Instrumentation Developments and Hot Metal Cluster Decays2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents instrumentation developments and measurements performed at the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. DESIREE operates at cryogenic temperatures ~13 K, with very low background pressures of ~10-14mbar, allowing the observation of stored ions to long times of tens of seconds and longer.

    Investigations into improving the count rate capability of the DESIREE detectors are presented. Microchannel plate (MCP) detectors are used for position sensitive particle counting in the DESIREE detector assemblies. In a cryogenic environment the operational resistance of MCPs is orders of magnitude higher than at room temperature and this limits the possible count rates. Novel low-resistance MCP detectors were investigated and resulted in the replacement of the MCPs in the DESIREE detector assemblies.

    DESIREE was used to measure spontaneous decays of hot, small cluster anions. The decays of small silver, copper and gold cluster anions are presented and compared to statistical model calculations. An experiment that is able to measure the proportion of spontaneous decay due to fragmentation or electron detachment in dimer anions of silver and copper is presented and significant, previously overlooked, contributions from electron detachment to the decay is identified. Furthermore, measurements of the stability and decay of small carbon cluster dianions are presented. These experiments utilised the aforementioned low-resistance MCPs.

  • Public defence: 2019-05-10 13:00 David Magnussonsalen (U31), Stockholm
    Tyrberg, Mårten
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Bringing psychological treatment to the psychiatric ward: Affecting patients, staff, and the milieu2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The psychiatric ward is a complex setting. This has to do partly with the severity of the patients’ suffering. Often, they present with such diagnoses as psychosis, self-harm, substance abuse, and suicidality. In fact, they often present with a combination of these. This renders the delivery of effective treatment a challenging task. Partly, the complexity of the ward has to do with aspects of the context itself. Admissions and discharges often happen fast and unexpectedly, staff members are expected to handle various challenging behaviors, they display quite high levels of burnout and work dissatisfaction, and the wards are often staffed by bank staff, leading to a lack of continuity of care. This adds to the challenge of delivering effective treatment. In the typical Swedish ward, treatment consists of medication, nursing, observation, and management of risk behaviors. Psychological treatment is seldom a routine part of inpatient care. However, there are sound arguments for adding psychological treatment in the form of cognitive behavior therapy (CBT) of various modalities. Further, there is promise in psychosocial interventions delivered by the nursing staff after appropriate training, and in providing supervision to the staff.

    The aim of the present thesis was to investigate the feasibility and potential efficacy of acceptance and commitment therapy (ACT), a CBT based psychotherapy model, as a broadly applied intervention in the context of psychiatric inpatient care. In three studies, ACT was evaluated as a brief individual psychotherapy intervention, and as a psychologically informed approach to dealing with patients performed by the nursing staff group in a psychiatric ward for psychosis patients.

    In study I, an average of two sessions of ACT was delivered to patients (n = 11) with a diagnosis of psychosis. Compared to a control group (n = 10), the risk for rehospitalization during a four-month follow-up period was significantly smaller for patients in the experimental group. There was also a trend toward increased values-based living scores in the experimental group, compared to controls.

    Study II evaluated the effects on staff members (n = 20) and patients (n = 9) of a brief ACT training intervention tailored to the staff group, the aim of which was to introduce ACT as a day-to-day approach to dealing with patients. After a total of 12 hours of ACT training, the staff group displayed a slight increase in work-related psychological flexibility, compared to before, while a non-randomized control group (n = 18) displayed a slight decrease. Patients being treated on the ward after the staff training displayed a slight increase in psychological flexibility during ward treatment, while patients being treated before displayed a slight decrease. In both cases, however, the differences were considered quite small (non-significant in statistical terms). Further, the study investigated ACT-consistent behavior changes among staff members following ACT training, using a multiple baseline single-subject design. Results revealed both expected and unexpected patterns of behavior.

    In study III, the usefulness of the ACT model was investigated using a qualitative content analysis. Staff members (n = 10) experienced ACT as useful in terms of dealing with patients’ struggles, enriching typical duties, and dealing with their own stress. Difficulties in using the model related to time restraints, complexities of the model itself, and the severity of patients’ illnesses.

    In summary, the present thesis adds to the research basis for ACT as a treatment for psychosis, delivered in an inpatient setting. It shows that the introduction of ACT as an add-on to traditional ward treatment in Sweden is for the most part feasible and acceptable. However, the thesis also discusses various challenges in the implementation of psychological treatment in such a complex context as the inpatient ward, both in terms of delivery of the treatment itself and the evaluation of its effectiveness.

  • Public defence: 2019-05-15 13:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Ciftci, Sibel
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Padlock Probe-Based Nucleic Acid Amplification Tests: Point-of-care Diagnostics of Infectious Diseases2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Recent advancements in molecular biology and biotechnology have pushed the field of molecular diagnostics much further to benefit the society towards smart access for rapid and simplified health care. In this context, point-of-care (PoC) technologies that bring the inventions in diagnostics closer to bedside settings draw attention. This becomes all the more relevant in the case of infectious diseases which pose the major burden, in terms of mortality and economic loss, especially for third world developing countries with resource-limited settings (RLS). Moreover, emerging and re-emerging viruses, known for their rapid mutation rates, demand huge attention in terms of timely diagnosis and the need for effective treatments. Hence, appropriate and accurate tests to detect the pathogens with enhanced sensitivity and specificity would be needed to bridge the gap between bioanalytics and clinics.

    This research work is an attempt to combine the tools and techniques required for the development of such efficient PoC technologies to combat infectious diseases. Among available nucleic acid-based amplification tests, padlock probing and isothermal rolling circle amplification are used to benefit from the advantages they offer for diagnostic applications, in terms of specificity, multiplexability, single molecule detection, high throughput, compatibility with various read-out platforms and inexpensive digital quantification.

    In the first paper, simultaneous detection of RNA and DNA forms of adenovirus is shown to study the spatio-temporal expression patterns in both lytic and persistent infections. In situ quantification of viral DNA as well as transcripts with single cell resolution has been achieved. In the second paper, novel probe design strategy has been presented for the development of molecular assays to detect hypervariable RNA viruses. This approach becomes helpful in targeting rapidly evolving viruses by using mutation-tolerant probes for RCA. Third paper demonstrates simple RCA for rapid detection of Ebola virus in clinical samples, followed by a multiplexed detection with other re-emerging tropical viruses, namely Zika and Dengue. This study also includes a simple easy-to-operate pump-free membrane enrichment read-out, combined together with microscopy for digital quantification of the products. In the fourth paper, near point-of-care glucose sensor-based RCP detection has been proposed for Ebola virus detection. All these attempts clearly bring RCA closer to PoC settings for molecular diagnostics of virus infections.

  • Public defence: 2019-05-16 10:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Kahle, Maximilian
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Assembly and Function of Nitric Oxide Reductase from Paracoccus denitrificans2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bacterial denitrification is a part of the global nitrogen cycle and comprises the stepwise reduction of nitrate to molecular nitrogen, which is released to the atmosphere. Cytochrome c-dependent nitric oxide reductase (cNOR) from Paracoccus (P.) denitrificans catalyzes the reduction of nitric oxide to nitrous oxide and water. This is a key step of the denitrification chain as it involves reformation of the N-N bond that was split in nitrogen fixation processes. In addition, nitric oxide is cytotoxic and nitrous oxide is a potent greenhouse gas. cNOR is an integral, two-subunit membrane protein, which contains several redox-active metal cofactors essential for function. In P. denitrificans the enzyme is expressed from an operon norCBQDEF, of which only norCB are the structural genes for the cNOR protein. The assembly process of cNOR, including cofactor insertion, as well as the detailed catalytic function of the enzyme are largely unknown, which motivated this study.

    Our results showed that cNOR can be expressed from only the norCB genes and that norQDEF are not essential for folding, complex formation and heme cofactor assembly of the protein. However, we found that non-heme iron (FeB) cofactor insertion into cNOR was dependent on the NorQ and NorD proteins, which were expressed from the nor operon. These proteins were purified as a complex and our results indicate that they act as a molecular chaperone. We present the cryo-electron microscopy structure of NorQ, which formed hexameric ring-shaped oligomers and was shown to have ATPase activity. Our data further suggest that NorD functions as an adaptor protein in order to link NorQ to a specific binding site at the cytoplasmic surface of cNOR. Based on our experimental data we present a model for FeB cofactor insertion into cNOR.

    Without co-expression of the NorQ and NorD proteins, the produced cNOR was inactive. It lacked FeB at the catalytic center but was otherwise structurally intact. Therefore we used this protein to investigate the role of FeB in the mechanism of nitric oxide and oxygen reduction of cNOR and compared our results to computational studies of the enzyme published recently.

    In vitro studies of membrane proteins, such as cNOR, are challenging because their function often depends on the interaction with a biological membrane and specific phospholipids. We used two different membrane mimetic systems, lipid nanodiscs and proteoliposomes, to study the effect of a membrane environment on the function of detergent-solubilized cNOR. Our results indicate that the membrane bilayer of lipid nanodiscs and proteoliposomes, even when assembled using the same lipids, has different properties with measurable effects on cNOR function.

  • Public defence: 2019-05-16 10:00 sal 14, hus 5, Kräftriket, Stockholm
    Lashari, Abid Ali
    Stockholm University, Faculty of Science, Department of Mathematics.
    Stochastic epidemics on random networks2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis considers stochastic epidemic models for the spread of epidemics in structured populations. The asymptotic behaviour of the models is analysed by using branching process approximations. The thesis contains four manuscripts.

    Paper I is concerned with the study of the spread of sexually transmitted infections, or any other infectious diseases on a dynamic network. The model we investigate is about the spread of an SI (Susceptible → Infectious) type infectious disease in a population where partnerships are dynamic. We derive explicit formulas for the probability of extinction and the threshold parameter R0 using two branching process approximations for the model. In the first approximation some dependencies between infected individuals are ignored while the second branching process approximation is asymptotically exact and only defined if every individual in the population can have at most one partner at a time. By comparing the two approximations, we show that ignoring subtle dependencies in the dynamic epidemic model leads to wrong prediction of the probability of a large outbreak.

    In paper II, we study a stochastic SIR (Susceptible → Infectious → Removed) epidemic model for the spread of an epidemic in populations structured through configuration model random graphs. We study the asymptotic (properly scaled) time until the end of an epidemic. This paper heavily relies on the theory of branching processes in continuous time.

    In paper III, the effect of vaccination strategies on the duration of an epidemic in a large population is investigated. We consider three vaccination strategies: uniform vaccination, leaky vaccination and acquaintance vaccination.

    In paper IV, we present a stochastic model for two successive SIR epidemics in the same network structured population. Individuals infected during the first epidemic might have (partial) immunity for the second one. The first epidemic is analysed through a bond percolation model, while the second epidemic is approximated by a three-type branching process in which the types of individuals depend on their status in the percolation clusters used for the analysis of the first epidemic. This branching process approximation enables us to calculate a threshold parameter and the probability of a large outbreak for the second epidemic. We use two special cases of acquired immunity for further evaluation.