The type-IV secretion system (T4SS) is a machinery able to transfer DNA and proteins between bacteria and in certain cases also to eukaryotic cells. This thesis compared the T4SSs present in... Show moreThe type-IV secretion system (T4SS) is a machinery able to transfer DNA and proteins between bacteria and in certain cases also to eukaryotic cells. This thesis compared the T4SSs present in Agrobacterium tumefaciens and the conjugative plasmid RP4. A. tumefaciens is able to transfer DNA into plant cells and transform them genetically. We discovered that a novel hairpin structure on the terminus of the transferred DNA allows for earlier expression of its genes in the recipient plant cell. Further, we could describe the translocation signal of the relaxase protein TraI of RP4 responsible for DNA processing and transfer via the T4SS. Additionally, it was shown that the T4SS of RP4 is able to translocate proteins from one cell to another without parallel DNA transfer. Furthermore, we were able to create a hybrid relaxase created consisting of parts from A. tumefaciens (relaxase part) and RP4 (translocation signal) that was shown to be translocated via the T4SS of RP4. Show less
When observing star-forming galaxies, we are not only seeing stellar light, but we also see how this interacts with galactic gas and dust. This thesis contains studies of the stellar, nebular and... Show moreWhen observing star-forming galaxies, we are not only seeing stellar light, but we also see how this interacts with galactic gas and dust. This thesis contains studies of the stellar, nebular and dust properties of low mass star-forming galaxies. We analyse data from the first statistical sample of low mass galaxies with stellar masses down to 10^7 solar masses, and investigate the emission from the stellar populations and their impact on and properties of the ionised surrounding gaseous nebulae, in order to understand the amount of ionising photons that are produced and the fraction of these that can escape from the galaxies. Since the stellar masses in low-mass systems may be stochastically sampled, we predict the influence of this on their nebular emission lies, and in particular on the derivation of their gas metallicity (the abundances of elements heavier than hydrogen and helium in the gas). To interpret observations of galaxies correctly, it is important to know the amount of interstellar dust grains, and its impact on the stellar and nebular light. We therefore finalise this thesis with a new method to derive dust properties in star-forming galaxies. Show less
The thesis has been an attempt to make sense of the political discourse in Kashmir from the early 1940s till the emergence of the popular uprising in the Valley towards the late 1980s. The thesis... Show moreThe thesis has been an attempt to make sense of the political discourse in Kashmir from the early 1940s till the emergence of the popular uprising in the Valley towards the late 1980s. The thesis has tried to underscore the fragmented nature of the political in Kashmir, and the implications it has had on the politics of the region, particularly on the politics of rai-shumari (self determination) and aazadi. These inner fragments or contradictions that underline the political life in Kashmir may be attributed, as the thesis has sought to argue, to the multiple political subjectivities that constitute ‘Kashmiri people’ as a community. Show less
This research investigates the changing landscape and land use in two case studies of the coastal villages of St. Kitts and the Kalinago Territory of Dominica. By integrating human and ecological... Show moreThis research investigates the changing landscape and land use in two case studies of the coastal villages of St. Kitts and the Kalinago Territory of Dominica. By integrating human and ecological aspects of agrarian landscapes, this research analyzes how land degradation or land change impacts cultural ecosystem services, that ultimately disrupts community wellbeing. First, as a primary goal, the research focus is established together with local communities or stakeholders, identifying both direct and indirect causes of landscape change. Second, by using a variety of qualitative and quantitative methods, but grounded in local participation, the research indicates that landscape change never happens in a vacuum but rather, it is always a part of a larger socio-political context and historical background that must be considered. In both case studies, there remains emphasis on the tangible, as results not only lead to new directions in landscape research but also deliverables used by community stakeholders for continued land sustainability. By investigating the synergies of nature and community within landscape change, this research proposes that local communities assert local agency. This moves away from how local communities fit into global phenomena of land change, to how communities can assert their diversity within a global process. Show less
Life expectancy is rising fast, but not all years gained are free of disease. Therefore, many people wonder to what extent the years that we have gained are enjoyable. Studies however show that... Show moreLife expectancy is rising fast, but not all years gained are free of disease. Therefore, many people wonder to what extent the years that we have gained are enjoyable. Studies however show that life satisfaction generally remains high at old age. We investigate this surprising phenomenon using data from two cross-sectional studies. We ask 1) which factors separate older people with a low from those with a high life satisfaction? And 2) how do older people maintain their high life satisfaction despite physical decline? Compared to earlier studies, this study used large and representative populations, and a broad array of objective health indicators. Physical decline was relatively unimportant for life satisfaction, especially when mental health (operationalised as depressive symptoms and experienced loneliness) remained high. Demographic variables and social resources also had no or a small relationship with life satisfaction. Only mental health was strongly associated with life satisfaction. By investigating various ways of measuring self-rated health, we show that older people may shift their norms and values in the face of declining health. This may thus explain their high life satisfaction, in spite of physical decline. Findings are discussed in relation to other literature and implications are given. Show less
This thesis demonstrates the application of bioinformatics to investigate the mechanisms that are implicated in Huntington’s Disease (HD). HD is an inherited neurodegenerative disorder and although... Show moreThis thesis demonstrates the application of bioinformatics to investigate the mechanisms that are implicated in Huntington’s Disease (HD). HD is an inherited neurodegenerative disorder and although the cause of the disease is known since 1993 we are still lacking a cure or treatment that can effectively treat the symptoms of HD. In order to tackle such a complicated case study, we followed a multidisciplinary approach to exploit the expertise and knowledge of people with diverse scientific background (chapter 2). This blend of disciplines facilitates constant collaboration between bioinformaticians, wet lab technicians, biologists, computer engineers and data scientists. A collaborative eScience model is proposed as a way to combine state-of-the-art computation analysis and laboratory work (chapter 3). At the same time, we explored methods to preserve the results, materials and methods involved in the experiment to increase the reproducibility and reusability of our research (chapter 4). In chapter 5 we identified disease signatures in blood that are functionally similar to signatures in brain. These are proposed as candidate biomarkers to be used as a monitoring tool for the state of the disease in brain, but also as a means to determine whether a treatment is successful or not. Show less
What do elections mean for a single-party regime? Can party-selected deputies do something meaningful for citizens in non-democracies? The dissertation explores how and under what conditions a... Show moreWhat do elections mean for a single-party regime? Can party-selected deputies do something meaningful for citizens in non-democracies? The dissertation explores how and under what conditions a single-party authoritarian regime instrumentalizes popularly elected congress to strengthen its rule in local society. It takes contemporary China as an empirical focus for this exploration. Instead of perceiving Chinese congress either simply as authoritarian window dressing or as an immediate catalyst for democratization, this research is devoted to examining the motivations, strategies, and behaviors of the party regime in playing the cards of congressional elections and representation to make its rule more robust and resilient. This project mainly adopts comparative case study methods, with some quantitative data serving as supportive statistical evidence. As a whole, my thesis argues that congressional election and post-election representation are two cards of China’s party regime. By strategically downplaying input electoral competition but promoting output congressional representation, the communist regime has been striving to develop a mass-line democracy as an alternative to liberal democracy, which features the “Leninist trinity” of the Party’s leadership, the rule of law, and people’s democracy, as well as a new brand of mobilized representation relying on the accountability from the top down. Show less
'What is the desire of the medium?' is both a rhetorical question and a fundamental one. The rhetorical question serves as a framework for investigating the interplay between the artist/designer... Show more'What is the desire of the medium?' is both a rhetorical question and a fundamental one. The rhetorical question serves as a framework for investigating the interplay between the artist/designer and the medium during the creative act. Arts and design operate on the level of problematising: they do not reproduce the visible, they make visible. By this, I am suggesting that there is no preconceived objective criterion: all perception needs to be produced. A critical supposition is that the complexity of the world cannot be reduced to either macro- or micro-systems or models (anti-representation). The only interesting route to pursue is to investigate what a medium does (asignification), not what it is (essentialism). My interest lies in affective capacities, not inherent properties and their respective place in any taxonomy or ontological setting. This requires the exploration of a non-hierarchical, flat ontology based on the equality of all parties (human and nonhuman). I propose four backgrounds against which to investigate the desire of the medium: ethoscape (which deals with affect), ideoscape (which deals with concepts), mediascape (forms of expression) and technoscape (forms of content). The desire of the medium is located somewhere in the middle between affect, concept, expression and content. Show less
Stars near massive black holes move on elliptical orbits which precess slowly, exerting persistent gravitational torques on each other. In this the- sis we present four important consequences of... Show moreStars near massive black holes move on elliptical orbits which precess slowly, exerting persistent gravitational torques on each other. In this the- sis we present four important consequences of these gravitational torques: 1) A new instability which exposes the inherently unstable nature of ec- centric stellar disks in galactic nuclei, 2) A density depression of stars near massive black holes due to enhanced angular momentum relaxation and tidal disruptions, 3) A signature of high-eccentricity orbits for stars formed by Hills__ mechanism at large radii from the massive black hole, and a directly-observable statistic that can highlight these populations, and 4) A new dynamical process which we call "secular dynamical anti-friction" which boosts the orbital eccentricity of hypothesized intermediate-mass black holes as they spiral into massive black holes Show less
The Wende results in two opposite effects: the university maintains its continuity and quickly starts to thrive in the newly unified German state, while the professional practice of most professors... Show moreThe Wende results in two opposite effects: the university maintains its continuity and quickly starts to thrive in the newly unified German state, while the professional practice of most professors suffers from discontinuity and a lack of connection to the new social circumstances. This antithesis, continuity for the university versus discontinuity for professorial practice, is the central theme. Relatively minor differences between biographies that had developed in the GDR op untill the Wende can be used to explain why the unification of Germany has widely divergent effects for the five hunderd professors of the Humboldt-Universit_t Show less
This thesis describes experiments, in which we used an optical-tweezers setup to study a number of biological systems. We studied the interaction between the E. coli molecular chaperone SecB and a... Show moreThis thesis describes experiments, in which we used an optical-tweezers setup to study a number of biological systems. We studied the interaction between the E. coli molecular chaperone SecB and a protein that was being unfolded and refolded using our optical tweezers setup. Our measurements clearly showed that in the presence of SecB, an unfolded protein could not refold. Molecular dynamics simulations were used to successfully explain features that were observed in our unfolding experiments. Our approach enables studies on other chaperones, as well. Next, we aimed to study translocation of single proteins through membranes by the E. coli Sec translocase. We modified an often-used model protein for our experiment. Different used experimental strategies are presented. Future experiments should enable measurements on the translocation of a single protein. The last study was on the packaging of double-stranded DNA by a single bacteriophage phi29. We aimed to study the effect of multivalent cations on the negatively-charged, tightly-packed DNA inside the bacteriophage capsid and in that way on the speed of the packaging process. A special DNA molecule was constructed and used in a number of successful packaging experiments. Future experiments should show the effect of cations on the packaging rate. With Summary in Dutch Show less
