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  • Public defence: 2017-03-27 10:00 Lecture hall FB42, Stockholm
    Hameedi, Muhammad Alley
    Stockholm University, Faculty of Science, Department of Physics.
    Single Photon Sources and Single Quantum System enabled Communication2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Quantum information is a highly interesting and fast emerging field that involves processing information encoded into quantum systems and their subsequent use in various information tasks. The use of quantum resources such as superposition and entanglement have shown to enhance information processing capabilities beyond classical means in a number of communication, information and computation tasks. In this thesis, we have used single photons to study the advantage of d-level quantum systems (qudits) for a communication task commonly known as random access codes (RACs). A successful experimental demonstration of quantum random access codes (QRACs) with four dimensions is realized to demonstrate that the higher dimensional QRACs not only outperform the classical RACs but also provide an advantage over their quantum bit (qubit) counterparts. QRACs are also studied in regards to two specific applications: certification of true randomness and for testing the non-classicality of quantum systems. A method for increased certification of generated randomness is realized for the former and a successful experimental demonstration of a test of non-classicality with arbitrarily low detection efficiency is provided for the latter. This is followed by an implementation of a QRAC in a one-path communication network consisting of preparation, transformation and measurement devices. We have shown that the distributed QRAC provides optimal success probabilities for a number of tasks. Moreover, a novel quantum protocol for the solution to the problem of dining cryptographers and anonymous veto voting is also presented. This single photon transmission based protocol provides an efficient solution, which is experimentally demonstrated for a 3-party description. Lastly, Nitrogen-Vacancy (NV) center in diamond is studied as a potential resource for single photon emission and two methods to enhance the photon collection efficiency are successfully explored. Due to this enhancement, single photons from an NV center may also be used in similar single quantum system based communication experiments.

  • Public defence: 2017-03-30 10:00 sal FB52, AlbaNova universitetscentrum, Stockholm
    Gladh, Jörgen
    Stockholm University, Faculty of Science, Department of Physics.
    Ultrafast Probing of CO Reactions on Metal Surfaces: Changes in the molecular orbitals during the catalysis process2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents experimental studies of three different chemical reaction steps relevant for heterogeneous catalysis: dissociation, desorption, and oxidation. CO on single-crystal metal surfaces was chosen as the model systems.

    X-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) provide information about the electronic structure, and were performed on CO/Fe to measure both a non-dissociative, and a pre-dissociative state. The measurement on the pre-dissociative state showed a π →  π* excitation, which implies a partly broken internal π bond in the molecule.

    Ultrafast laser-induced reactions were used to examine the dynamic properties of desorption and oxidation. Here CO/Ru and CO/O/Ru were used as model systems. Desorption of CO from a Ru surface involve both hot electrons and phonons. In the case of CO oxidation from CO/O/Ru a pronounced wavelength dependence of the branching ratio between desorption and oxidation was observed. Excitation with 400 nm showed a factor of 3-4 higher selectivity towards oxidation than 800 nm. This was attributed to coupling to transiently excited, non-thermalized electrons.

    Finally, by performing optical pump/x-ray probe XAS and XES changes in the electronic structure during the reaction could be followed, both for desorption and oxidation. In the CO/Ru experiment, two different transient excitation paths were observed, one leading to a precursor state, and one where CO moves into a more highly coordinated site. Using selective excitation in XES, these were shown to coexist on the surface. In the oxidation experiment, probing the reacting species located near the transition state region in an associative catalytic surface reaction was demonstrated for the very first time.

  • Public defence: 2017-03-30 10:00 Nordenskiöldsalen, Geovetenskapens hus, Stockholm
    Lang, Lisa
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    SOD1 Aggregation: Relevance of thermodynamic stability2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease affecting the upper and lower motor neurons causing muscle atrophy and paralysis followed by death. Aggregates containing superoxide dismutase (SOD1) are found as pathological hallmark in diseased ALS patients. Consequently ALS is regarded as a protein misfolding disorder like Alzheimer’s disease and Parkinson’s disease. So far, little is known about the cause and mechanism behind SOD1 aggregation but the inherent property of all polypeptide chains to form stable aggregated structures indicates that the protein misfolding diseases share a common mechanism.

    Our results show that SOD1 aggregation starts from the globally unfolded state, since fibrillation is fastest at full occupancy of denatured protein induced either by chemical denaturation or mutation. Even so, the fibrillation rate shows a surprisingly weak dependence on the concentration of globally unfolded SOD1 indicating fibril fragmentation as the dominant mechanism for aggregate formation. This is further supported by the observation that the SOD1 sample has to be mechanically agitated for fibrillation to occur.  Interestingly, we observe a similar SOD1 aggregation behaviour in vivo, where the survival times of ALS transgenic mice correlates with mutant stability, and aggregate growth depends weekly on the concentration of unfolded monomer. Additionally, in-cell NMR measurements reveal that in live cells the thermodynamic equilibrium is shifted towards the unfolded state of SOD1, which is also more fully extended than in vitro. This suggests that the globally unfolded aggregation competent protein is more abundant in the crowded environment in vivo than dilute in vitro conditions. Finally, antibody analysis of aggregates from ALS transgenic mice reveals the existence of aggregate strains involving different parts of the protein depending on mutation, which may offer an explanation for the various disease phenotypes observed in ALS. Altogether these findings provide important clues for understanding SOD1 aggregation with implications for ALS, as well as other protein misfolding diseases.

  • Public defence: 2017-03-31 10:00 hörsal 11, hus F, Stockholm
    Mondani, Hernan
    Stockholm University, Faculty of Social Sciences, Department of Sociology.
    Modeling Organizational Dynamics: Distributions, Networks, Sequences and Mechanisms2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The study of how social organizations work, change and develop is central to sociology and to our understanding of the social world and its transformations. At the same time, the underlying principles of organizational dynamics are extremely difficult to investigate. This is partly due to the difficulties of tracking organizations, individuals and their interactions over relatively long periods of time. But it is also due to limitations in the kinds of quantitative methods used to tackle these questions, which are for the most part based on regression analysis.

    This thesis seeks to improve our understanding of social organizing by using models to explore and describe the logics of the structures and mechanisms underlying organizational change. Particular emphasis is given to the modeling process, the use of new concepts and analogies, and the application of interdisciplinary methods to get new insights into classical sociological questions.

    The thesis consists of an introductory part and five studies (I-V). Using Swedish longitudinal data on employment in the Stockholm Region, the studies tackle different dimensions of organizational dynamics, from organizational structures and growth processes to labor mobility and employment trajectories. The introductory chapters contextualize the studies by providing an overview of theories, concepts and quantitative methods that are relevant for the modeling of organizational dynamics. 

    The five studies look into various aspects of organizational dynamics with the help of complementary data representations and non-traditional quantitative methods. Study I analyzes organizational growth statistics for different sectors and industries. The typically observed heavy-tailed statistical patterns for the size and growth rate distributions are broken down into a superposition of interorganizational movements. Study II models interorganizational movements as a labor flow network. Organizations tend to be more tightly linked if they belong to the same ownership sector. Additionally, public organizations have a more stable connection structure. Study III uses a similarity-based method called homogeneity analysis to map out the social space of large organizations in the Stockholm Region. A social distance is then derived within this space, and we find that the interorganizational movements analyzed in Studies I and II take place more often between organizations that are closer in social space and in the same network community. Study IV presents an approach to organizational dynamics based on sequences of employment states. Evidence for a positive feedback mechanism is found for large and highly sequence-diverse public organizations. Finally, Study V features an agent-based model where we simulate a social influence mechanism for organizational membership dynamics. We introduce a parameter analogous to a physical temperature to model contextual influence, and the familiar growth distributions are recovered as an intermediate case between extreme parameter values.

    The thesis as a whole provides suggestions for a more process-oriented modeling approach to social organizing that gives a more prominent role to the logics of organizational change. Finally, the series of methodological tools discussed can be useful for the analysis of many other social processes and more broadly for the development of quantitative sociological methods.

  • Public defence: 2017-03-31 13:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Webling, Kristin E
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Design, Synthesis and Characterization of Galanin Receptor Selective Ligands2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Galanin is a 29/30 amino acid long bioactive peptide discovered over 30 years ago when C-terminally amidated peptides were isolated from porcine intestines. The name galanin originates from a combination of the first and last amino acids - G from glycine and the rest from alanine. The first 15 amino acids are highly conserved throughout species, which indicates that the N-terminus is important for receptor recognition and binding. Galanin exerts its effects by binding to three different G protein-coupled receptors, which all differ according to regional distribution, the affinity for shortened galanin fragments, as well as the intracellular G-protein signaling cascade used. When first discovered, galanin was found to cause muscle contraction as well as hyperglycemia.  Over the years, galanin has been reported to be involved in a wide variety of biological functions, for example food intake and neurogenesis, and pathological functions, for example epilepsy and depression.

    Determining the specific involvement of the three different galanin receptors in biological and pathological processes is limited by the small amount of galanin receptor selective/specific ligands available as research tools. Furthermore, the fast degradation of peptides limits the administration routes in animal studies.

    This thesis aims at developing new galanin receptor-selective ligands to help delineate the involvement of the three different galanin receptors.

    Paper 1 presents the shortest galanin fragment with a galanin receptor 2 specific binding preference where only a single amino acid substitution was made, Ala5Ser in galanin (2-11). In addition, G-protein coupled receptor signaling were evaluated through both a classical second messenger assay and a real-time label-free technique in cells overexpressing the receptor as well as low receptor expression.

    Paper 2 demonstrates that the neuroprotective effects of galanin in a kainic acid-induced excitotoxic animal model were mediated through galanin receptor 1. Furthermore, a new robust protocol for evaluating G-protein signaling using a label-free real time impedance technique was presented and compared to two different classical second-messenger assays.

    Paper 3 presents a series of systemically active galanin receptor 2 selective ligands subsequently evaluated in two different depression-like animal models.

    Paper 4 investigates a mutated form of human galanin which was found in epilepsy patients and binding and signaling properties of the mutated associated ligand p.(A39E) was examined.

    In conclusion, this thesis presents the discovery of eight new galanin ligands, which can be used to evaluate the galaninergic system as well as to help investigate the possible use of peptides as pharmaceuticals in different diseases.

  • Public defence: 2017-03-31 13:00 Auditoriet, Humanistvillan, Stockholm
    Wistisen, Lydia
    Stockholm University, Faculty of Humanities, Department of Culture and Aesthetics. 840925-0282.
    Gångtunneln: Urbana erfarenheter i svensk ungdomslitteratur 1890–20102017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis shows that the urban experience is a fundamental part of the development of the Swedish young adult novel by analysing city representations in Swedish young adult literature from 1890 to 2010. By suggestion that there is a strong bond between the notion of the urban and that of adolescence this study examines continuity and change in representations of coming-of-age, focusing especially on intersections between age, gender, class, ethnicity and sexuality.

    During the 20th century Stockholm has become the most common setting in Swedish literature for young adults. Young adult literature has been involved in a constant dialogue both with society’s view on adolescents, and with the city of Stockholm. A central line of argument is that the subject position of the protagonist determines the depiction of the relationship between youth and urban space. Depictions of identity development, emancipation and maturity processes are located to passages between family home and adult life, to peripheral spaces beyond the control of the adult world, as well as to public places of display.

    The methodology is inspired by spatial studies and is founded on the idea that the city of Stockholm is a product of a constant process of human practices, perceptions and conceptions. Movement trough space generate meaning of what the city is on a real, as well as on a textual, level. Young adult literature can change the way adolescents view the world around them, making possible new ways of understanding what is actually there and catalysing new ideas about what might be.

    The material consists of up to 30 works set in Stockholm from 1890 to 2010. The selection contains both girls’ and boys’ books, as well as books for young adults. The positioning of teenage characters and of stories of emancipation, growth, and clashes between generations has gone through several changes during the studied period. The analysis therefore point out six greater themes, which focus on different urban time-bound experiences, motifs, and places: early 20th century literary urban aesthetics, 1950’s consumer and car culture, 1960’s and 1970’s suburban youth, homelessness motifs and, finally, new motifs from the turn of the millennium.

  • Public defence: 2017-03-31 13:00 Lilla hörsalen, Naturhistoriska riksmuseet, Stockholm
    Carm, Ellen
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Caught in Culture?: Cultural Transformation through HIV/AIDS Prevention Education in Zambia2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The study explores the role and contribution of education in developing a localized and relevant HIV/AIDS prevention strategy through a multi-voiced approach, involving the educational institutions, as well as the traditional leaders, community-members, including parents. The study comprised all public schools in one Zambian province from 2002-2008.  The study explores, among other factors, the role of traditional culture in mitigating and exacerbating the spread of the disease.

    Zambia was one of the countries hardest hit by the HIV/AIDs epidemic, and one of the few countries in the region that, in 2002, had a clear policy on the role of education in fighting the epidemic. Through the process of developing and implementing a learner-centered interactive HIV/AIDS education program in the province. based upon MOE`s  HIV/AIDS policies and strategies, syllabi, and teachers guides, and at the same time emphasizing the broader community as a point of departure.

    The qualitative and interpretivist research was conducted within a constructivist grounded theoretical approach. The study applies comprehensive and multilayered perspectives while utilizing a broad range of methods.   Documentary analyses, structured and semi-structured interviews, in depth conversations with traditional and educational leaders, teachers, parents and pupils, were all carried out during the period of the study. Nvivo, a computer-supported data analysis tool was used to support the process of categorizing the qualitative data and the study applied Cultural- and Historical Activity Theory for analytic purposes.

    The study revealed the mismatch between the decentralized, national HIV/AIDS prevention education approach, as stated in the policy documents and the global UNAIDS, centralized and cross-sectoral strategies favored by the Zambian government. The uncoordinated efforts did not reach  the grassroots level, where professionals, at district and school level, perceived and applied policies in highly different ways, if at all reaching students and the communities.

    The main categories of drivers of the epidemic were of socio-cultural and economic character, e.g. polygamy, sexual cleansing, local healing, gender inequality and poverty,  sexual violence, multiple concurrent sexual partners and prostitution, but there were also variety of local drivers, depending upon context.

    When analyzing the participatory approaches of the HIV/AIDS prevention strategy, predominantly, at the school-community level, the findings revealed that the traditional leaders, being legitimate leaders in their kingdoms, and the custodians of culture and traditions, were found to be gate openers to promote behavioral change and cultural transformation in their villages.

    The traditional leaders worked hand in hand with the schools and the villagers. Their involvement legitimated that discourses and HIV/AIDS prevention actions were taken at school as well as within their own chiefdom. Utilizing their traditional leadership structures, the chiefs sustained their cultural rites, e.g. cleansing, in order to chase away the evil spirits, by turning the rites into practices that do no put people at risk for contracting HIV. Particularly at the global and state level, culture has been seen as drivers of the epidemic. The study revealed that the traditional leaders used their role as significant others, became gate-openers, using their legitimate role as custodians of culture to transform cultural rites and practices.

  • Public defence: 2017-03-31 14:00 Gröjersalen, hus3, Stockholm
    Giovacchini, Elia
    Stockholm University, Faculty of Social Sciences, Stockholm Business School.
    Weaving the symbiotic relationship: A longitudinal study of the maintenance of a firm-sponsored open source community2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The phenomenon of firm sponsored open source software (OSS) projects has become an established and widely used approach to develop and release new products in the software industry. In this arrangement, a sponsoring firm and a community establish a relationship to create a common project. When a firm fully commits to this type of development, it enters into a symbiotic relationship with its OSS community. This implies their mutual dependence and the presence of competing demands, both for openness – so that everyone can contribute to the common project and appropriate value from it, and for control – to affect the project content and direction. Although earlier studies have recognized the paradoxical nature of these competing and interrelated demands, so far there have been only limited attempts to understand its implications for maintaining such a symbiotic relationship.

    Hence, the aim of this thesis is to deepen our understanding of the symbiotic relationship by answering the following question: How is a symbiotic firm-community relationship maintained?

    To address this question, a qualitative research design is adopted through a single in depth longitudinal case study of the relationship between a Nordic European firm and its OSS community throughout their 13 plus years of history, from 2002 till 2015, by combining archival resources, observations and interviews. Recognizing the nature of these competing demands, a paradox lens is introduced as a way to frame the firm-community relationship.

    This allows identification of six paradoxical tensions that affect the relationship and five responses used to address the paradoxical tensions as they manifest. Building on these different insights a conceptual model of the firm-community relationship is developed. The model highlights that responses in many instances become the cause of subsequent paradoxical tensions. This insight underpinned the search for an alternative understanding of maintenance beyond instances of single tensions and response, by suggesting three different approaches to maintaining the firm-community relationship, namely, improvising, separating and weaving. 

    This study contributes to extant literature by giving prominence to the relationship as a conduit of interaction in which both the firm and community should be able to extend their influence while also being subject to the influence of each other. In particular, based on the insights of the weaving approach, I suggest understanding maintenance as a process of creation, where quite apart from the design of the relationship, there is a need to reconsider the features of key actors, not solely in terms of motivation, but also including their knowledge, skill and ways of thinking.

  • Public defence: 2017-04-04 13:00 Lilla Hörsalen, Naturhistoriska riksmuseet, Stockholm
    Dutt, Khaleda Gani
    Stockholm University, Faculty of Social Sciences, Department of Education.
    The Role of Adult Literacy in Transforming the Lives of Women in Rural India: Overcoming Gender Inequalities: Comparative case studies in Bhilwara District Rajasthan & Howrah District West Bengal India2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The Indian diaspora is woven around castes, languages, dialects, religions- a young nation boasting of an ancient civilization in which inequalities are deeply ingrained in its culture and traditions. Although vital government interventions have succeeded in increasing the literacy rate of women in both urban and rural areas general household characteristics such as income, caste, occupation and education attainments of parents still continue to determine access, attendance, completion and learning outcomes of girls and women from severely disadvantaged communities. The critical issue investigated in the comparative case study is why and how established hegemonic roles changed because of the catalytic role of adult literacy. The research was conducted in Bhilwara District, Rajasthan and Howrah District, West Bengal, India where literacy has played an intrinsic role in transforming the lives of the rural and marginalized women. In Indian society social norms often prevent women from exercising their free choice and from taking full and equal advantage of opportunities for individual development, contribution and reward. So assessing empowerment/transformation would mean identifying the constraints to empowerment, how women’s agency has developed and finally looking if ‘agency’ was able to address the constraints to women’s access to adult literacy. This would also entail seeking answers to questions such as ‘How is transformation represented in their narratives? What was the impact of literacy upon their lives?

  • Public defence: 2017-04-06 13:00 Vivi Täckholmssalen (Q211), Stockholm
    Nguyen, Thi Thanh Van
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    The actinorhizal symbiosis of the earliest divergent Frankia cluster2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In recent years, the need to reduce reliance on synthetic nitrogen fertilizer has led to extensive research on biological nitrogen fixation, especially on root nodule symbioses. My study focuses on actinorhizal symbioses, the symbiotic interactions between members of nitrogen-fixing soil actinobacteria from the genus Frankia and a diverse group of plants from eight families, collectively called actinorhizal plants. Frankia cluster II has been shown to be sister to all other clusters. Thus, one of my aims was to gain insight into this cluster to get more information about the evolution of actinorhizal symbioses. The first sequenced genome of a member from this cluster Candidatus Frankia datiscae Dg1 originated from Pakistan. This strain contains the canonical nod genes nodABC responsible for the synthesis of lipochitooligosaccharide Nod factors. In this thesis, we obtained three Frankia inocula from North America (USA), one from Europe (France), one from Asia (Japan) and one from Oceania (Papua New Guinea). Thirteen metagenomes were sequenced based on gDNA isolated from root nodules of Datisca glomerata (Datiscaceae), Ceanothus thyrsiflorus (Rhamnaceae), Coriaria myrtifolia and Coriaria arborea (Coriariaceae). This study shows that members of Frankia cluster II come in teams, helping to explain the ability of cluster II to nodulate a wide host range, four families from two orders. The inoculum from Papua New Guinea, the only sequenced strain from the Southern Hemisphere so far, contains a new Frankia species, which was proposed as Candidatus Frankia meridionalis. All cluster II strains in this study contain the canonical nod genes nodABC, with the exception of the strain from Papua New Guinea which contains only nodB’C. All North American metagenomes also contain the sulfotransferase gene nodH. This gene shows host plant-specific expression in that it was expressed in nodules of C. thyrsiflorus but not in D. glomerata. Phylogenetic analysis and transposase frequencies of the new genomes strongly support the hypothesis that the extension of the cluster II host range from Coriaria to Datisca occurred in Eurasia and that cluster II strains came to North America via the Bering Strait. To acquire more information of the influence of the host plant on the behavior of the microsymbionts, the bacterial metabolism in nodules of D. glomerata (Cucurbitales) and C. thyrsiflorus (Rosales) were compared at the level of transcription. The system to protect nitrogenase from oxygen in Ceanothus nodules seems to be more efficient than in Datisca nodules, whereas the bacterial nitrogen metabolism is likely to be similar in both host plants. The amino acid profile of D. glomerata nodules shows that the nitrogenous solutes are dominated by glutamate and arginine, supporting the suggestion that Frankia in D. glomerata nodules exports an assimilated form of nitrogen, most likely arginine. Thus, our data show that cluster II Frankia strains differ from all other Frankia clusters with regard to the presence of the canonical nod genes and their nitrogen metabolism in symbiosis. 

  • Public defence: 2017-04-07 10:00 Vivi Täckholmsalen (Q-salen), NPQ-huset, Stockholm
    von Essen, Gabriella
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Energy flow and metabolic efficiency attributed to brown adipose tissue2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The large capacity of brown adipose tissue (BAT) to expend energy as heat makes it an interesting potential player in weight regulation and other metabolic conditions. This is of particular interest as it has been recognized that adult humans possess BAT. The protein responsible for the heat production is uncoupling protein 1 (UCP1), which, as the name implies, uncouples the respiratory chain from ATP production; instead heat is produced. Cold is the strongest recruiter and activator of BAT. However, also obesogenic food has a low but nonetheless significant effect on the recruitment and activation of UCP1, although the significance of this has been discussed.

    In the present thesis, I have studied the effect of diet on BAT and the possibilities for it to be obesity-protective. This can be done by comparing responses in wild-type mice and in UCP1-ablated mice. Since the effect of diet on BAT is low, it is of importance to control the temperature and maintain thermoneutrality. Other confounding factors to keep in mind are differences in actual energy and composition of food and also cohort differences. When controlling all the parameters mentioned and giving the mice the same obesogenic diet, the mice possessing UCP1 compared to UCP1-ablated mice had higher energy expenditure, and lower weight gain, despite eating more. This confirms the presence of a UCP1-dependent diet-induced thermogenesis. Thus, the conclusion must be that possessing UCP1 does result in obesity protection at thermoneutrality. However, the relevance for human energy balance is still not established.

  • Public defence: 2017-04-07 13:00 sal FA32, AlbaNova universitetscentrum, Stockholm
    Jakobsson, Emma
    Stockholm University, Faculty of Science, Department of Physics.
    Shapes of Spacetimes: Collected tales of black holes2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In theory, the existence of black holes is predicted by general relativity. In reality, there is a general consensus that they exist in space; in particular at the center of many galaxies. The theory of black holes has been around for decades, but there are still interesting questions calling for attention. This doctoral thesis and its four contributions touches upon some of these questions.

    One challenging theoretical aspect of black holes lies in their definition, the event horizon. For several reasons, this definition is not satisfactory in many contexts, and alternative horizons based on the concept of trapped surfaces have been suggested to take its place. The question raised in Paper I has to do with the location of such surfaces in a simple model of gravitational collapse, the Oppenheimer-Snyder model.

    A different scenario of gravitational collapse, that of a null shell of dust collapsing in flat spacetime, is the starting point of the original formulation of the Penrose inequality. By a reformulation, this inequality can be turned into a purely geometric relation in Minkowski space. In Paper IV we formulate and prove a (2+1)-dimensional version in anti-de Sitter space.

    The Penrose inequality sometimes goes under the name of the "isoperimetric inequality for black holes". In Paper III a different kind of isoperimetric inequality is discussed (with less rigour), namely that of the volume contained in a black hole with a given area.

    In Paper II, the subject of limits of spacetimes is visualized. Again, (2+1)-dimensional anti-de Sitter space finds its use, as a one parameter family of surfaces, capturing the geometry of charged black hole spacetimes, is embedded in it. Thus different limiting procedures are illustrated.

    Finally, interesting models can be constructed by cutting and gluing in spacetimes, but in doing so one needs to take care, in order to obtain a physically realistic model. With this background as motivation, a study of Lorentzian cones is given.

    Taken together, all of these contributions make up a collection of interesting aspects of black hole geometry, or, shapes of spacetimes.

  • Public defence: 2017-04-20 13:00 Gröjersalen, hus 3, Kräftriket, Stockholm
    Johansson, Janet
    Stockholm University, Faculty of Social Sciences, Stockholm Business School.
    “Sweat is weakness leaving the body”: A study on the self-presentational practices of sporty top managers in Sweden2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Embracing the symbolic interactionist view of the notion of self, applying dramaturgical theories of self-presentation, this study unpacks the linkage between leaders’ lifestyle behaviours (in athletic endeavours) and the formation of their sense of self as occupants of the leadership role from a self-expressive perspective.  I conducted a study of a group of sporty top managers in Sweden. With interviews and observations, I anchored the research focus in verbal expressions within storytelling and in performative expressions of the top managers. Drawing on social interpretations of sport and athleticism and with a dramaturgical analytical frame, I examine how the sporty top managers interpret their athletic endeavours to express important values, beliefs and concerns to express ‘whom they want to become’ as occupants of the leadership role.

    The analysis shows that lifestyle behaviours in athletic endeavours serve as a new source of self-meanings with which the sporty top managers create and express wishful notions about themselves as occupants of the leadership role. By incorporating athletic values with their distinctive understanding of a ‘good leader’, the top managers seek to present themselves with an idealized image of ‘athletic leaders’. In this process, the top managers outline a role-script that is mainly characterized with self-disciplinary qualities and masculine values, they define the leadership context with athleticism in the centre, and they express an overt intent to elevate some people and exclude others in organizational processes based on athletic values in which they personally believe. Hence, the process of formation of self as ‘athletic leaders’ is not only ‘self-relevant’, but it is personally, interpersonally and socially (organizationally) meaningful. The analysis also shows that the top managers seek to give legitimacy and an elitist status to the idealized view of self by using expressive strategies to appropriate their appearances, regulate emotions and bodily senses, and mould a gendered self-image.  

    This thesis contributes to leadership studies in several ways. First, the study expands on extant literature theorizing the linkage between lifestyle behaviours and the formation of sense of self as occupants of the leadership role from a new angle. It contends that lifestyle behaviours such as athletic endeavours have become a prime site where business leaders express creative narratives regarding an idealized view of themselves. Second, this study further advocates that the formation of sense of self of leaders is not a simple outcome of different forms of regulative discursive regime.  Rather, this process involves creative self-reflexive activities that address individuals’ personally held values, their distinctive pursuits in becoming an idealized leader, relations with others, and some prevailing leadership notions that they believe to be closely associated with the nature of lifestyle behaviours in which they engage and commit. Third, this study confirms the notion that the formation of the understanding of self of leaders is not only a function of verbal expressive devices, but that it also involves individuals’ performative strategies in ‘expressive control’ (e.g. Down & Reveley, 2009; Goffman, 1959). This thesis adds to understanding this point of view through a discussion of self-presentational practices in non-work related activities. Finally and most importantly, this study suggests that the process of formation of the sense of self of business leaders is expressive of meanings on personal, interpersonal and social dimensions in its own right. That is, through creating new self-meanings in micro-level practices in lifestyle behaviours, the occupants of the leadership role define the situational characteristics (the leadership context), express intentions to enact the power feature of inclusion and exclusion of others; generate new understanding of the leadership role, and they reproduce and strengthen some prevailing leadership ideals.