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  • Disputas: 2018-04-26 10:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Görbe, Tamás
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Heterogeneous catalysis in racemization and kinetic resolution along a journey in protein engineering2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The first part of my thesis concerns the use of heterogeneous acidic resins for racemization of tert-alcohols without any side-product formation. The focus was to develop a system which can be further extended to a DKR protocol consisting of an enzymatic KR reaction. Based on our knowledge of the resins, an unexpected migratory DKR protocol turned out to be an efficient method for the synthesis of carbocyclic allylic carbinols.

    The development of enzyme and metal catalyst hybrids was already an ongoing theme in our group. A supporter-free biohybrid catalyst was developed which can be used in several different types of reactions. The Pd(0)-CalB CLEA catalyst was applied in a two-step-cascade transformation and in the DKR of benzylic primary amines. The catalyst was characterized by different analytical techniques, to understand its composition and structure.

    The enzymes have always been the main focus of the studies and therefore wild type enzymes were initially utilized. However, these natural biocatalysts are associated with certain limitations. In contrast, protein engineering allows for enzymes to be modified and optimized. We have used the technique to create a subtilisin Carlsberg mutant, which was studied both by modeling and in vitro. The mutant was found to catalyze the (S)-selective transesterification of sec-alcohols containing long aliphatic carbon chains, and it also exhibited higher performance in organic solvent.

    The last project concerned the protein engineering of CalA enzyme towards tert-alcohols. The kinetic resolution of tert-alcohols with this enzyme is very slow but it occurs with good enantioselectivity. The aim was therefore to improve the activity of CalA via protein engineering. Seven amino acids were mutated close to the active site and a library was created based on our prediction. Throughout the screening, a few variants showed higher activity, which were sequenced and further analyzed in the transesterification of tert-alcohols.

  • Disputas: 2018-04-27 10:00 Nordenskiöldsalen, Geovetenskapens hus, Stockholm
    Mwakagali, Mpoki
    Stockholms universitet, Juridiska fakulteten, Juridiska institutionen.
    International Financial Institutions and Labour Standards: A Legal Study of the Role of These Institutions in the Promotion and Implementation of Freedom of Association and Collective Bargaining2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This dissertation examines the legal implications of the operations of international financial institutions (IFIs) on international labour standards on freedom of association and collective bargaining. International financial institutions provide financial assistance to member states for development activities and attach conditionality to their lending. These conditionalities require recipient states to carry out policy reforms, which in some cases include labour market reforms, thereby affecting labour standards in recipient states. In addition, the IFIs provide other forms of support such as policy advice and technical assistance. On basis of their ability to affect labour policy, the dissertation explores the role that these institutions play to promote and implement these labour rights. A number of  cases are included in the study to show the practices of the IFIs and the effects of their operations on labour rights. Using the International Labour Organisastion (ILO) fundamental conventions on freedom of association and collective bargaining as the point of reference, the study assesses the legal consequences of development finance on these fundamental labour rights.

  • Disputas: 2018-04-27 10:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Gustafson, Karl P. J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies on Metalloenzymatic Dynamic Kinetic Resolutions and Iron-Catalyzed Reactions of Allenes2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The main focus of this thesis lies in the development of new transition metal-catalyzed chemoenzymatic dynamic kinetic resolutions (DKR) of both alcohols and amines. The first part of the thesis deals with the development of new heterogeneous systems for the DKR of amines. The racemization catalysts in these different systems are all composed of palladium nanoparticles supported on either mesoporous silica or incorporated in a biocomposite that is composed of a bioactive cross-linked enzyme aggregate. 

    The second part of the thesis deals with the development of a homogeneous iron catalyst in the racemization of sec-alcohols for the implementation in a chemoenzymatic DKR. Two protocols for the racemization of sec-alcohols are reported. The first one could not be combined with a chemoenzymatic kinetic resolution, although this was overcome in the second iron based protocol. 

    Following the successful iron catalyzed chemoenzymatic DKR of sec-alcohols, the iron catalyst was used in the cyclization of α-allenic alcohols and N-protected amines to furnish 2,3-dihydrofurans and 2,3-dihydropyrroles, respectively. The cyclization is proceeding in a diastereoselective manner.

    The last part of the thesis deals with attempts to further elucidate the mechanism of activation of a known ruthenium racemization catalyst. X-ray absorption spectroscopy using synchrotron radiation was used for this purpose.

  • Disputas: 2018-04-27 10:00 Högbomsalen, Geovetenskapens Hus, Stockholm
    Wang, Kun
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut.
    Transcription regulation and growth phase transition in hyperthermoacidophilic archaea2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Organisms from the domain Archaea are ubiquitously represented on our planet and encompass diverse fascinating organisms. The genus Sulfolobus belonging to the phylum Crenarchaeota including hyperthermoacidophilic strains that grow optimally at 65-85°C and pH 2-3. These organisms have been used as model organisms for thermophiles to investigate archaeal DNA replication, transcription, translation, cell cycle, etc.

    The focus of this thesis is on the study of archaeal specific transcription factors (TFs) as well as transcriptome changes during growth phase transition of the hyperthermoacidophilic archaeons Sulfolobus acidocaldarius and Sulfolobus solfataricus, respectively, to expand our knowledge on archaeal transcription regulation and growth phase adaptation.

    In paper 1, we studied the genome-wide binding sites of BarR, which is a β-alanine responsive Lrp family TF that activates the expression of β-alanine aminotransferase located in a divergent operon in S. acidocaldarius. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) revealed 21 binding regions, including previously characterized barR/Saci_2137 intergenic region. However, only one additional operon containing two glutamine synthase genes (Saci_2320 and Saci_2321) was found to be under activation of BarR. This operon is a common target of LyM and Sa-Lrp, which indicates a regulatory network between different Lrp-like regulators. In paper 2, we showed that a TetR family transcription repressor FadRSa regulates fatty acid metabolism in S. acidocaldarius. FadRSa rests in a gene cluster, Saci_1103-Saci_1126, that mainly contains lipid degradation and fatty acid metabolism genes. ChIP-seq revealed four binding sites within the gene cluster and RNA-seq further confirmed that the entire gene cluster is repressed by FadRSa. FadRSa binds DNA at a 16-base pair motif with dyad symmetry, and binding of medium- to long-chain acyl-CoA molecules resulted in dissociation of FadRSa from the DNA. Although FadRSa is similar to its bacterial counterparts functionally and structurally, fundamentally different ligand binding mode has been observed.

    In paper 3, transcriptome data of S. solfataricus at four time points during growth, including early exponential phase, late exponential phase, early stationary phase and late stationary phase, has been studied and revealed a massive change in gene expressions during growth phase transition. 1067 out of a total of 2978 (35.8%) protein coding genes were identified as differentially expressed, which included 456 induced genes most of which were related to transposase, metabolism and stress response, 464 repressed genes most of them involved in translation, basic transcription, DNA replication, amino acids metabolism and defence mechanisms, and 147 genes with fluctuated profile including transporters, oxidation-reduction process related genes and few metabolic genes.

    In summary, the studies of two metabolic related TFs in S. acidocaldarius, BarR and FadRSa, shed light on their function and regulatory mechanisms. In addition, the transcriptome data of S. solfataricus not only reveals genome-wide alteration of gene expression during growth phase transition, but also provide a rich source of information for further studies by the archaea research community.

  • Disputas: 2018-04-27 10:00 De Geersalen, Geovetenskapens hus, Stockholm
    González-Fernández, Tania
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Socialantropologiska institutionen.
    Feeling Across Distance: Transnational Migration, Emotions, and Family Life Between Bolivia and Spain2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    What are the relational dynamics of family life as it is lived across vast distances and over time? What underpins these relations, practices, and experiences of being apart and yet together? Based on a long-term multi-sited fieldwork carried out in Spain and Bolivia from 2013 to 2015, this study sets out to address these questions by investigating caring practices, mediated connections, (non)material exchanges, and lived experiences of “doing” and “feeling” family across borders. It conveys the story of ten families divided between Madrid and the Bolivian urban areas of Cochabamba, Sucre, and Santa Cruz de la Sierra. Taking as a point of departure the encounters with middle-aged women who migrated to Spain in the early 2000s, the thesis moves back and forth between “here” and “there” to provide a polyphonic account of family relationships as they are sustained, enacted, and experienced by both those who leave and those who stay. It does so by exploring the transnational provision of care, the routines of keeping in touch, the exchange of remittances and material goods, as well as the interplay of these practices with the management of emotions and the circulation of affects. The term “affective maps” is employed here as a concept to capture the myriad of relatives taking part in these connections, in that it points out how these are strongly interdependent relationships through which people have the capacity to affect and to be affected by one another across distance. More specifically, this study demonstrates how the various ways of dealing with transnational family life are constantly shaped by migration regimes, restrictive policies, and global inequalities, on the one hand, and by power social relations, gender and generational roles, and life-course stages, on the other. To illuminate the dynamics at play, the notion of “feel-work” is introduced as a tuned-in ethnographic practice that simultaneously engages the body and the mind, reasoning and feeling. This study is thus a multi-sited ethnography contributing further knowledge into emotions and affects in human mobility, while it consistently uses emotions and affects as methodological and epistemological tools. The thesis argues that family members recreate a sense of “closeness” and maintain their emotional connection despite not being physically together nor seeing each other over long periods of absence. Ultimately, in grappling with the affective dimension of family relationships in the distinct context of current Bolivia-to-Spain migration, this thesis aims to shed some light on the emotional and the corporeal as constitutive aspects of the ethnographic endeavor.

  • Disputas: 2018-04-27 10:00 sal FA32, AlbaNova universitetscentrum, Stockholm
    Higgins, Gerard
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. University of Innsbruck, Institute for Experimental Physics.
    A single trapped Rydberg ion2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Systems of trapped ions and systems of ultracold Rydberg atoms are used at the forefront of quantum physics research and they make strong contenders as platforms for quantum technologies. Trapped Rydberg ions are a new hybrid technology envisaged to have both the exquisite control of trapped ion systems and the strong interactions of Rydberg atoms. 

    In this work a single trapped Rydberg ion is experimentally investigated. A trapped 88Sr+ ion is excited to Rydberg states using two ultraviolet lasers. Effects of the strong trapping electric fields on the sensitive Rydberg ion are studied. After mitigating unwanted trap effects, the ion is coherently excited to Rydberg states and a quantum gate is demonstrated. This thesis lays much of the experimental groundwork for research using this novel system.

    Fulltekst tilgjengelig fra 2019-04-27 09:00
  • Disputas: 2018-04-27 13:00 Hörsal 11, hus F, Stockholm
    Gavelin, Karin
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Statsvetenskapliga institutionen. Ersta Sköndal Bräcke högskola.
    The Terms of Involvement: A study of attempts to reform civil society's role in public decision making in Sweden​2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    For the better part of a century, a distinguishing feature of the Swedish democratic model has been the close relationship between organised interests and public decision makers. Yet the first decade of the twenty-first century saw a number of attempts to reform Swedish civil society’s role in decision making, purportedly to make involvement activities more inclusive, reciprocal, flexible and consequential. The aim of this thesis is to describe and understand the motivations behind and the meaning of these reform attempts. Using an interpretive research design, and drawing on constructivist institutionalist perspectives on organisational change, the study asks questions about what has driven the attempted reform, how affected actors have interpreted its meaning and consequences, and how its framing and outcomes have been affected by the fact that it was devised and implemented both in traditional organisations and in networks consisting of local and national actors from civil society and the public sector. The thesis constitutes a contribution to the constructivist institutionalist literature concerned with the micro-foundations of organisational behaviour and to the governance research literature, to which it contributes empirical insights about how governance reforms have been interpreted and rationalised in Sweden.

  • Disputas: 2018-04-27 13:00 William-Olssonsalen, Geovetenskapens hus, Stockholm
    Swärd, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    In the wake of deglaciation - sedimentary signatures of ice-sheet decay and sea-level change: Studies from south-central Sweden and the western Arctic Ocean2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Lacustrine and marine sedimentary archives help unravel details concerning the withdrawal of large ice sheets and resulting sea-level changes during the last deglaciation (22 -11 kyr). In a series of four manuscripts, this PhD thesis investigates the sedimentological signatures from deglacial processes at three key locations in the northern hemisphere: (i) Lake Vättern (LV) in south-central Sweden, (ii) Herald Canyon (HC) in the western Chukchi Sea, and (iii) Mackenzie Trough (MT) on the westernmost edge of the Canadian Beaufort Shelf. One lacustrine (LV) and two marine (HC and MT) sediment cores were analyzed using a broad range of methods to describe the physical, chemical, mineralogical and biological characteristics, and used to construct paleoenvironmental interpretations.

    Constituting the westernmost part of the Baltic Sea during parts of the last deglaciation, LV has long been envisaged as a key region for deglacial studies in southern Scandinavia. Sediments in LV highlight four major lake development stages following the withdrawal of the Fennoscandian Ice Sheet. These include the Baltic Ice Lake, the Yoldia Sea, the Ancylus Lake and the ultimate isolated lake stage. New radiocarbon dates indicate that the lake became isolated at 9530±50 cal. yr BP. A sharp transition from a varved clay unit to a partly sulfide laminated clay unit marks the final drainage of the Baltic Ice Lake, dated to 11 650±280 cal. yr BP. However, an earlier peak in pore water chlorinity identified in the sediment provides the most compelling evidence to date for an initial drainage of the Baltic Ice Lake (~12.8 cal. kyr BP) near the onset of the Younger Dryas cold event.

    Located downstream from where Pacific water flows into the Arctic, HC is a key location for understanding the details of the early Holocene (~11 cal. yr BP) flooding of the Bering Strait, and investigating sedimentological proxies for Pacific water in Arctic Ocean sediment cores. The deglacial transgression of the shelf and opening of the Bering Strait is reflected in the grain size and biogenic silica content from the HC sediment core. However, a clear Pacific water signature is not seen in the clay mineralogy which exhibits increased variability after the opening of the Bering Strait. This is interpreted as a combination of Pacific and East Siberian sources for bottom waters in HC. The absence of a clear Pacific water signature in the clay mineralogy highlights potential limitations to using this proxy in other records from the western Arctic.

    Far field studies from the Arctic Ocean have argued that Mackenzie River sediments in Younger Dryas age sediments can be recognized by a unique mineral and isotopic composition, but no detailed proximal study of Mackenzie River sediments exists to support this assertion. The mineral and isotopic (Sr and Nd) studies presented in this thesis from the third of the key regions, the MT, fills this gap. The results show that the mineral assemblage and ɛNd of fine fraction material remained relatively stable during the decay of the Laurentide Ice Sheet. An exception to this exists in a transitional sedimentary unit, deposited immediately after transgression at the site, and might be related to meltwater pulses associated with the drainage of the Lake Agassiz. The results suggest that the modern mineral and isotopic signature of Mackenzie River sediments may not be a suitable proxy for deglacial meltwater events in far field sedimentary records.

  • Disputas: 2018-05-03 10:00 Magnélisalen, Stockholm
    Larsson, Veronica J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Characterization of the inner nuclear membrane protein Samp1, during interphase and mitosis2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The nucleus, a hallmark in eukaryotic cells, contains the genome separating it from molecules in the cytoplasm. The nucleus is surrounded by a nuclear envelope consisting of two concentric membranes, the outer nuclear membrane and the inner nuclear membrane, the nuclear lamina and nuclear pore complexes. The cytoskeleton is physically connected with the nucleoskeleton by the LINC complexes, spanning the nuclear envelope. In this way, the cell surface is linked directly to chromatin. There are hundreds of unique inner nuclear membrane proteins, but today we only know the functions of a handful. The best characterized inner nuclear membrane proteins are involved in chromatin organization and gene regulation.

    This thesis focuses on Samp1, an integral membrane protein that localizes to the inner nuclear membrane during interphase. During mitosis, a fraction localizes to the mitotic spindle, which is responsible for accurate segregation of chromosomes.

    It is difficult to investigate inner nuclear membrane protein-protein interactions, because transmembrane proteins are often associated with the “hard-to-solubilize” nuclear lamina. MCLIP was developed as a method to detect interactions between proteins of the nuclear envelope in live cells. MCLIP has been valuable in identifying interaction partners of Samp1. In interphase, Samp1 distributes in distinct micro-domains of the inner nuclear membrane and interacts with the nuclear lamina, emerin and the LINC complex protein SUN1, suggesting that Samp1 might have a functional role associated with both the nucleoskeleton and cytoskeleton.

    In mitosis Samp1 distributes in filamentous membrane structures partially overlapping with kinetochore microtubules of the mitotic spindle. Samp1 binds directly to γ-tubulin and recruits γ-tubulin and Haus6 to the mitotic spindle and thus contributes to spindle assembly. Samp1 also interacts with Aurora B, a kinase important for k-fiber error correction at the kinetochores. Depletion of Samp1 caused an increased activation and distribution of Aurora B at the metaphase plate, decreased formation of stable k-fibers, metaphase prolongation and increased chromosome mis-segregation. Samp1 is the first transmembrane protein found to be involved in mitotic spindle assembly and stability, important for correct segregation of chromosomes.



  • Disputas: 2018-05-04 10:00 Magnéli Hall, Chemical Practice Laboratory, Stockholm
    Heusser, Stephanie A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Allosteric modulation of pentameric ligand-gated ion channels by general anesthetics2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Pentameric ligand-gated ion channels (pLGICs) are key components of fast synaptic transmission and are targets of neuroactive drugs such as benzodiazepines, alcohol and muscle relaxants. Although early theories of general anesthesia suggested non-specific lipid interaction as the mechanism of anesthetic action, it has now become evident that they too bind to pLGICs. While general anesthetics act as positive allosteric modulators on most anion-conducting pLGICs, they inhibit cation-conducting channels. A detailed structural mechanism of how such opposite allosteric effects emerge has yet to be presented.

    This thesis investigates the structure-function relationship underlying the dynamics of channel activation and explores the mechanisms behind allosteric modulation by general anesthetics. Key model systems include the glutamate-gated chloride channel of C. elegans (GluCl) and the G. violaceus ligand-gated ion channel (GLIC), that show considerable structural homology to mammalian channel but with the added simplicity of homomeric assembly and accessibility to crystallization. Functional assessment is performed through recombinant expression of the channels in Xenopus oocytes, which are then used for two-electrode voltage clamp electrophysiology. These measurements are combined with recent advances in structure determination and computational simulations to propose structural mechanisms behind the functional effects.

    In this thesis I present the exploration and validation of the crystallographic construct GluCl as a model system to explore fundamental questions of mammalian pLGIC function. Further studies contribute to the understanding of the basis of allosteric modulation by identifying responsible binding sites for both potentiation and inhibition by general anesthetics in GLIC and substantiate a structural mechanism for these effects. The studies also offer a link between receptor- and lipid-based theories of anesthesia, and demonstrate successful discovery of new lead compounds with general anesthetic properties using virtual screening. The thesis therefore makes a contribution to the fundamental understanding of allosteric modulation in pLGICs and builds on the basis for rational drug discovery.

  • Disputas: 2018-05-04 13:00 Nordenskiöldsalen, Geovetenskapens hus, Stockholm
    Ye, Rebecca
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen.
    The Aspirants: How faith is built in emerging occupations2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Anticipating future demands in skills and workforce development has been a longstanding practice and challenge for governments and policy-makers. While such developments are examined closely at the national and regional levels, an even more pressing issue is to advance our understanding of how people who take on jobs in new and emerging fields embark on and persist in their occupational pathways. A striking feature of these occupations is their weakly defined and unstable nature. How do individuals traverse career trajectories with these characteristics? What drives and enables them to take the road less travelled? To address such questions, this research project set off from a distinctive occupational school in Sweden that prepares individuals for emerging occupational roles in digital work. Using an interpretative, longitudinal, and multi-method approach, this study focuses on a group of aspirants who were being trained to become specialists in extracting, analysing, and using digital data for the growth and profit of organisations. These individuals can be viewed as experiencing a double “not-yet” situation, since not only are they at the stage of aspiring to certain work roles, but the occupations to which they aspire are also in a nascent, not yet fully defined stage. This study accompanies them through significant events over the years: from when they are in training, to when they search for jobs, and, finally, when they are in work.

    The monograph contains three empirical sections that are sequenced by the aspirants’ school-to-work pathways. The first section examines the processes of socialisation into the occupational school; the second analyses their efforts to meet the labour market; and the final one investigates the ways in which they persist in their occupational trajectories. Following these stages reveals how a strong school culture, coupled with a strong labour market, facilitates the building of “faith” into weak-form occupational pathways. Through the ceremony of being selected into the educational organisation and performing everyday rituals that engender confidence in their individual and collective futures, the analysis reveals types of “scripts” that are fashioned into the school’s methodology as well as the expectations of future hirers. It becomes apparent that aspirants generally accept these scripts as necessary and adhere to them to navigate the constantly changing demands of the labour market. However, when these interpretive schemes fail to help them cope with their unclear occupational futures, uncertainties of worth, and the unstable normative logics they encounter at work sites, the aspirants are compelled to deliberate and adapt conceptions of what is possible and permissible through individual and collective projections. In all, the empirical findings form the basis for a sociological model that offers a perspective on how to treat temporality, anticipation, and the “not-yets”, particularly in the context of education to work transitions.

  • Disputas: 2018-05-04 13:00 sal FP41, hus 1, Stockholm
    Ertan, Emelie
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Quantum chemical calculations of multidimensional dynamics probed in resonant inelastic X-ray scattering2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is devoted to the theoretical study of the dynamical processes induced by light-matter interactions in molecules and molecular systems. To this end, the multidimensional nuclear dynamics probed in resonant inelastic X-ray scattering (RIXS) of small molecules, exemplified by H2O (g) and H2S (g), as well as more complex molecular systems, exemplified by NH3 (aq) and kaolinite clay, are modelled. The computational methodology consists of a combination of ab initio quantum chemistry calculations, quantum nuclear wave packet dynamics and in certain cases molecular dynamics modelling. This approach is used to simulate K-edge RIXS spectra and the theoretical results are evaluated against experimental measurements.

    Specifically, the vibrational profile for decay back to the electronic ground state of the H2O molecule displays a vibrational selectivity introduced by the dynamics in the core-excited state. Simulation of the inelastic decay channel to the electronic |1b1-1,4a11> valence-excited state shows that the splitting of the spectral profile arises from the contribution of decay in the OH fragment. The character of the S1s-1 and S2p-1 core-excited states of the H2S molecule has been investigated and distinct similarities and differences with the H2O molecule have been identified. RIXS has also been used as a probe of the hydrogen bonding environment in aqueous ammonia and by detailed analysis of the valence orbitals of NH3 and water, the spectral profiles are explained. Finally, it is shown that vibrations of weakly hydrogen bonding OH are excited in RIXS decay to the electronic ground state in kaolinite. 

  • Disputas: 2018-05-14 13:00 De Geersalen, Geovetenskapens hus, Stockholm
    Pateli, Evangelia
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Nationalekonomiska institutionen.
    Essays on International Trade: Theory and Evidence on the Determinants and Implications of Firms' Import Behaviour2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis aspires to further contribute to our understanding of both the determinants as well as the implications of intermediate goods trade. Faced with intensifying global competition, firms are increasingly developing their production process and their sourcing strategies beyond national borders in order to take advantage of lower costs, superior quality and technological advances.

    In the first two chapters, I analyse firm-level import decisions in an environment allowing for unintentional exchanges of import-relevant information between firms. I build on the idea that any import-specific knowledge acquired by established importers, in a given region/industry, spills over to prospective importers lowering the costs associated with entry in international markets for intermediates. Chapter 1, using firm-level import data on the universe of Swedish firms, at the product level and by source market for the period 1998-2011, provides evidence for the existence of import spillovers and offers insights into the mechanisms through which they operate. Chapter 2, sets out a theoretical framework formalising import spillovers and their implications for the firm’s import behaviour and for consumer welfare.

    In the third and last chapter of this thesis, I turn to intermediate import dependence with an aim to explain the lack of sensitivity of trade flows to exchange rate movements. I propose a tractable framework and study how real devaluations affect firm-level export decisions and export performance, as well as aggregate exports and welfare in an environment where final goods production uses both domestic and imported intermediates.

  • Disputas: 2018-05-15 10:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Mobarak, Hani
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis and analysis of carbohydrates related to bacterial polysaccharides2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The outer surface of bacteria is composed of around 75% carbohydrates, which are vital for the bacteria to survive and communicate with the host biological system. The thesis discusses different properties of carbohydrates that are essential for understanding the bacterial behavior in biological systems. The first three chapters give an overview of carbohydrates.

    The fourth chapter discusses the synthesis of four amide-substituted 3,6-dideoxy-α-D-galactopyranosides, namely, methyl α-3,6-dideoxy-3-formamido-, acetamido-, (R)-3-hydroxybutyramido-, and (4-hydroxybutyramido)-D-galactopyranoside. These sugars were found as components of some bacterial O-antigens; the study is a step toward the synthesis of oligosaccharides that contain them. The fifth chapter describes the exchange kinetics of the formyl and acetyl derivatives that were synthesized. Both of them have two conformational states for the amide side-chain. 13C-NMR saturation transfer experiments are utilized for these measurements to reveal more about their properties in solution.

    In chaptr six, NMR and conformational analysis of oligosaccharides related to the O-antigen of Yersinia enterocolitica O:3 bacteria were carried out to obtain more information regarding their 3D structure.

    Chapter seven is focusing on the development of CASPER, a program for rapid assignment of 1H- and 13C-NMR chemical shifts of bacterial lipopolysaccharides, by adding more sugars into its database and testing it for naturally occurring LPS as well as extending the scope for synthetic carbohydrates, which is planned to be developed further in the future.