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This doctoral dissertation aims at elucidating the development of hot and cool executive functions in middle childhood and at gaining insight about their role in childhood overweight. The dissertation is based on three empirical studies which have been published in peer-reviewed journals. Data from a large 3-year longitudinal study (the “PIER-study”) was used.
The findings presented in the dissertation demonstrated that both hot and cool EF abilities increase during middle childhood. They also supported the notion that hot and cool EF facets are distinguishable from each other in middle childhood, that they have distinct developmental trajectories, and different predictors.
Evidence was found for associations of hot and cool EF with body weight in middle childhood, which is in line with the notion that they might play a role in the self-regulation of eating and the multifactorial etiology of childhood overweight.
On a small scale
(2018)
This study argues that micro relations matter in peacekeeping. Asking what makes the implementation of peacekeeping interventions complex and how complexity is resolved, I find that formal, contractual mechanisms only rarely effectively reduce complexity – and that micro relations fill this gap. Micro relations are personal relationships resulting from frequent face-to-face interaction in professional and – equally importantly – social contexts.
This study offers an explanation as to why micro relations are important for coping with complexity, in the form of a causal mechanism. For this purpose, I bring together theoretical and empirical knowledge: I draw upon the current debate on ‘institutional complexity’ (Greenwood et al. 2011) in organizational institutionalism as well as original empirical evidence from a within-case study of the peacekeeping intervention in Haiti, gained in ten weeks of field research. In this study, scholarship on institutional complexity serves to identify theoretical causal channels which guide empirical analysis. An additional, secondary aim is pursued with this mechanism-centered approach: testing the utility of Beach and Pedersen’s (2013) theory-testing process tracing.
Regarding the first research question – what makes the implementation of peacekeeping interventions complex –, the central finding is that complexity manifests itself in the dual role of organizations as cooperation partners and competitors for (scarce) resources, turf and influence. UN organizations, donor agencies and international NGOs implementing peacekeeping activities in post-conflict environments have chronic difficulty mastering both roles because they entail contradictory demands: effective cooperation requires information exchange, resource and responsibility-sharing as well as external scrutiny, whereas prevailing over competitors demands that organizations conceal information, guard resources, increase relative turf and influence, as well as shield themselves from scrutiny. Competition fuels organizational distrust and friction – and impedes cooperation.
How is this complexity resolved? The answer to this second research question is that deep-seated organizational competition is routinely mediated – and cooperation motivated – in micro relations and micro interaction. Regular, frequent face-to-face interaction between individual organizational members generates social resources that help to transcend organizational distrust and conflict, most importantly familiarity with each other, personal trust and belief in reciprocity. Furthermore, informal conflict mediation and control mechanisms – namely, open discussion, mutual monitoring in direct interaction and social exclusion – enhance solidarity and mutual support.
Samarium hexaboride
(2018)
Through IOs' Eyes
(2018)
Is global governance characterized by overlap and fragmentation, or by coordination and harmonization? There are two rather different narratives about the worlds in which international organizations (IOs) live. One way or another, IOs are part of a broader environment and engage in relations with other actors in it. Rather than being detached from their environment, IOs are shaped by and respond to developments taking place within it (e.g., overlap). Thus, the general research interest of this dissertation lies in organizational responses to such environmental developments. Therein, the emphasis is placed on IO positionality, meaning the position of an IO within a “web” of interorganizational relations, or, more precisely, an IO’s position within an organizational field as a specification of the IO environment.
Against this background, the dissertation poses the following research question: How does an IO’s position within an organizational field shape its responses to developments of the field? In that, three subquestions are advanced: Which position does an IO occupy within the organizational field? How does an IO perceive the organizational field? How does an IO respond to developments and features of the field? Theoretically, the dissertation combines an open system perspective on IOs with two variants of field theory inspired by Bourdieu and by DiMaggio and Powell. Building on the central concept of the organizational field, the dissertation understands IOs as actors with agency. Empirically, the dissertation consists of a qualitative, comparative study and analyzes two IOs located within the organizational field of global food security governance. I select IOs that occupy different positions within the field of food security governance, namely an IO at the core of the field (the United Nations Food and Agriculture Organization, or FAO) and an IO at the periphery of the field (the United Nations Industrial Development Organization, or UNIDO). I compare and analyze their respective perceptions of the field of food security governance, including their own role and their understandings of food security, and their responses over time. To investigate these IOs’ perceptions and responses over time, the method of choice consists of a qualitative content analysis of a wide range of organizational documents (e.g., governing bodies’ reports).
The main argument this dissertation advances is as follows: The position that an IO occupies within an organizational field influences how the organization perceives its environment—in particular, features of and developments within this environment. Against this background, the main findings of this dissertation are as follows: Overall, FAO and UNIDO both perceive proliferation, overlap, and duplication as relevant developments of the organizational field of global food security governance over time. While both IOs see developments in the field of food security governance (e.g., overlap and duplication) as problematic given their detrimental effects for food security governance, FAO and UNIDO differ in decisive regards. Whereas FAO holds a narrative that other actors were responsible for this state of affairs, and thus responsible for reducing or even eliminating overlap and duplication, UNIDO perceives these developments differently. UNIDO acknowledges its own role in the development of overlap and duplication, and therefore also sees a role for itself in addressing these developments. The two IOs thus differ in what they understand to be the causes and historical priors of field-specific developments. Furthermore, while both FAO and UNIDO attempt to demonstrate that they are constructive players within the UN development system, the two IOs differ in their responses: While FAO engages in balancing by voicing its commitment to UN processes and to coordination, yet early on making different reservations, UNIDO, in contrast, engages in UN processes without similar reservations. Accordingly, the two IOs also differ on the responses they employ to field-level harmonization demands.
The dissertation makes several contributions. Theoretically, I contribute an innovative argument on the influence of perceptions for organizational responses to developments in the IOs’ environment. This argument may help us to better understand how IOs as actors embedded within an organizational field deal with changes evolving within these fields. Empirically, I scrutinize developments in food security governance, such as proliferation and overlap, through the eyes of IOs in the field. While proliferation, overlap, and duplication are often referred to in academic debates on food security governance, we do not yet actually understand these phenomena very well. To this, I contribute a study that analyzes IO perceptions of these developments in the field, thus resulting in a more in-depth and nuanced picture of how IOs perceive these developments as a central type of actor in food security governance. Next, to this emphasis on the IO perspective, I also inductively develop a spectrum of IO responses to field developments, ranging from expanding scope to defending turf. Finally, I also make a methodological-conceptual contribution: While concepts such as “position” are well-known, they are sometimes drawn on without developing a clear foundation of how to assess different positions. I thus add an approach for bringing this concept of position to life by developing a range of criteria that can be used to approximate an IO’s position within an organizational field, depending on different types of capital.
Climate change affects societies across the globe in various ways. In addition to gradual changes in temperature and other climatic variables, global warming is likely to increase intensity and frequency of extreme weather events.
Beyond biophysical impacts, these also directly affect societal and economic activity. Additionally, indirect effects can occur; spatially, economic losses can spread along global supply-chains; temporally, climate impacts can change the economic development trajectory of countries.
This thesis first examines how climate change alters river flood risk and its local socio-economic implications. Then, it studies the global economic response to river floods in particular, and to climate change in general.
Changes in high-end river flood risk are calculated for the next three decades on a global scale with high spatial resolution. In order to account for uncertainties, this assessment makes use of an ensemble of climate and hydrological models as well as a river routing model, that is found to perform well regarding peak river discharge. The results show an increase in high-end flood risk in many parts of the world, which require profound adaptation efforts. This pressure to adapt is measured as the enhancement in protection level necessary to stay at historical high-end risk. In developing countries as well as in industrialized regions, a high pressure to adapt is observed - the former to increase low protection levels, the latter to maintain the low risk levels perceived in the past.
Further in this thesis, the global agent-based dynamic supply-chain model acclimate is developed. It models the cascading of indirect losses in the global supply network. As an anomaly model its agents - firms and consumers - maximize their profit locally to respond optimally to local perturbations. Incorporating quantities as well as prices on a daily basis, it is suitable to dynamically resolve the impacts of unanticipated climate extremes.
The model is further complemented by a static measure, which captures the inter-dependencies between sectors across regions that are only connected indirectly. These higher-order dependencies are shown to be important for a comprehensive assessment of loss-propagation and overall costs of local disasters.
In order to study the economic response to river floods, the acclimate model is driven by flood simulations. Within the next two decades, the increase in direct losses can only partially be compensated by market adjustments, and total losses are projected to increase by 17% without further adaptation efforts. The US and the EU are both shown to receive indirect losses from China, which is strongly affected directly. However, recent trends in the trade relations leave the EU in a better position to compensate for these losses.
Finally, this thesis takes a broader perspective when determining the investment response to the climate change damages employing the integrated assessment model DICE. On an optimal economic development path, the increase in damages is anticipated as emissions and consequently temperatures increase. This leads to a significant devaluation of investment returns and the income losses from climate damages almost double.
Overall, the results highlight the need to adapt to extreme weather events - local physical adaptation measures have to be combined with regional and global policy measures to prepare the global supply-chain network to climate change.
Microbiota analyses of patients suffering from various diseases suggest a beneficial role of Akkermansia muciniphila in the maintenance of health, whereas several studies in animal models of intestinal inflammation report that this organism may aggravate inflammation. Therefore, it is important to clarify under which circumstances A. muciniphila exerts negative effects in the intestine of its host.
The previously reported observation that A. muciniphila aggravates acute intestinal inflammation in the Salmonella enterica serovar Typhimurium infection mouse model colonized with a simplified human intestinal microbiota was investigated in this study. To unravel the underlying mechanism that led to the observed phenomenon, the time course of events following the infection was analyzed. In mice colonized with a simplified human intestinal microbiota, Salmonella infection induced clear signs of intestinal inflammation three days post infection. The inflammatory response was similar in mice colonized with A. muciniphila before Salmonella infection. These observations were independent of the time when colonization with the simplified human intestinal microbiota occurred, right after birth or only after weaning, and contradict the previous report.
To find out whether A. muciniphila influences the development of chronic intestinal inflammation in a genetically predisposed host, mono-associated interleukin-10-deficient (Il10-/-) mice, Il10-/- mice dual-associated with A. muciniphila and colitogenic Escherichia coli NC101, as well as Il10-/- mice associated with A. muciniphila and a simplified human intestinal microbiota were compared to the respective mice without A. muciniphila. The data clearly show that in these gnotobiotic Il10-/- mice, A. muciniphila neither induces intestinal inflammation itself nor modulates it after induction by a colitogenic bacterium or by a simplified human intestinal microbiota.
The experiments lead to the conclusion that the promotion of intestinal inflammation is not an intrinsic feature of this bacterium. The results of this study encourage the proposed use of A. muciniphila for the prevention or treatment of metabolic disorders.
Synchrotron-based angle-resolved time-of-flight electron spectroscopy for dynamics in dichalogenides
(2018)
In this thesis, we discuss the characterization of orthogroups by so-called disjunctions of identities. The orthogroups are a subclass of the class of completely regular semigroups, a generalization of the concept of a group. Thus there is for all elements of an orthogroup some kind of an inverse element such that both elements commute. Based on a fundamental result by A.H. Clifford, every completely regular semigroup is a semilattice of completely simple semigroups. This allows the description the gross structure of such semigroup. In particular every orthogroup is a semilattice of rectangular groups which are isomorphic to direct products of rectangular bands and groups. Semilattices of rectangular groups coming from various classes are characterized using the concept of an alternative variety, a generalization of the classical idea of a variety by Birkhoff.
After starting with some fundamental definitions and results concerning semigroups, we introduce the concept of disjunctions of identities and summarize some necessary properties. In particular we present some disjunction of identities which is sufficient for a semigroup for being completely regular. Furthermore we derive from this identity some statements concerning Rees matrix semigroups, a possible representation of completely simple semigroups. A main result of this thesis is the general description of disjunctions of identities such that a completely regular semigroup satisfying the described identity is a semilattice of left groups (right groups / groups). In this case the completely regular semigroup is an orthogroup. Furthermore we define various classes of rectangular groups such that there is an exponent taken from a set of pairwise coprime positive integers. An important result is the characterization of the class of all semilattices of particular rectangular groups (taken from the classes defined before) using a set-theoretic minimal set of disjunctions of identities. Additionally we investigate semilattices of groups (so-called Clifford semigroups). For this purpose we consider abelian groups of particular exponents and prove some well-known results from the theory of Clifford semigroups in an alternative way applying the concept of disjunctions of identities. As a practical application of the results concerning semilattices of left zero semigroups and right zero semigroups we identify a particular transformation semigroup. For more detailed information about the product of two arbitrary elements of a semilattice of semigroups we introduce the concept of strong semilattices of semigroups. It is well-known that a semilattice of groups is a strong semilattice of groups. So we can characterize a strong semilattice of groups of particular pairwise coprime exponents by disjunctions of identities. Additionally we describe the class of all strong semilattices of left zero semigroups and right zero semigroups with the help of such kind of identity, and we relate this statement to the theory of normal bands. A possible extension of the already described semilattices of rectangular groups can be achieved by an auxiliary total order (in terms of chains of semigroups). To this end we present a corresponding characterization due to disjunctions of identities which is obviously minimal. A list of open questions which have arisen during the research for this thesis, but left crude, is attached.
Systemic inflammation is a hallmark of cancer cachexia. Among tumor-host interactions, the white adipose tissue (WAT) is an important contributor to inflammation as it suffers morphological reorganization and lipolysis, releasing free fatty acids (FA), bioactive lipid mediators (LM) and pro-inflammatory cytokines, which accentuate the activation of pro-inflammatory signaling pathways and the recruitment of immune cells to the tissue. This project aimed to investigate which inflammatory factors are involved in the local adipose tissue inflammation and what is the influence of such factors upon enzymes involved in FA or LM metabolism in healthy individuals (Control), weight stable gastro-intestinal cancer patients (WSC) and cachectic cancer patients (CC). The results demonstrated that the inflammatory signature of systemic inflammation is different from local adipose tissue inflammation. The systemic inflammation of the cachectic cancer patients was characterized by higher levels of circulating saturated fatty acids (SFA), tumor-necrosis-factor-α (TNF-α), interleukins IL-6, IL-8 and CRP while levels of polyunsaturated fatty acids (PUFAs), especially n3-PUFAs, were lower in CC than in the other groups. In vitro and in adipose tissue explants, pro-inflammatory cytokines and SFAs were shown to increase the chemokines IL-8 and CXCL10 that were found to be augmented in adipose tissue inflammation in CC which was more profound in the visceral adipose tissue (VAT) than in subcutaneous adipose tissue (SAT). Systemic inflammation was negatively associated with the expression of PUFA synthesizing enzymes, though gene and protein expression did hardly differ between groups. The effects of inflammatory factors on enzymes in the whole tissue could have been masked by differentiated modulation of the diverse cell types in the same tissue. In vitro experiments showed that the expression of FA-modifying enzymes such as desaturases and elongases in adipocytes and macrophages was regulated into opposing directions by TNF-α, IL-6, LPS or palmitate. The higher plasma concentration of the pro-resolving LM resolvin D1 in CC cannot compensate the overall inflammatory status and the results indicate that inflammatory cytokines interfere with synthesis pathways of pro-resolving LM. In summary, the data revealed a complex inter-tissue and inter-cellular crosstalk mediated by pro-inflammatory cytokines and lipid compounds enhancing inflammation in cancer cachexia by feed-forward mechanisms.
Spectroscopy at the limit
(2018)
Neuroinflammatory and neurodegenerative diseases such as Parkinson's (PD) and multiple sclerosis (MS) often result in a severe impairment of the patient´s quality of life. Effective therapies for the treatment are currently not available, which results in a high socio-economic burden. Due to the heterogeneity of the disease subtypes, stratification is particularly difficult in the early phase of the disease and is mainly based on clinical parameters such as neurophysiological tests and central nervous imaging. Due to good accessibility and stability, blood and cerebrospinal fluid metabolite markers could serve as surrogates for neurodegenerative processes. This can lead to an improved mechanistic understanding of these diseases and further be used as "treatment response" biomarkers in preclinical and clinical development programs. Therefore, plasma and CSF metabolite profiles will be identified that allow differentiation of PD from healthy controls, association of PD with dementia (PDD) and differentiation of PD subtypes such as akinetic rigid and tremor dominant PD patients. In addition, plasma metabolites for the diagnosis of primary progressive MS (PPMS) should be investigated and tested for their specificity to relapsing-remitting MS (RRMS) and their development during PPMS progression.
By applying untargeted high-resolution metabolomics of PD patient samples and in using random forest and partial least square machine learning algorithms, this study identified 20 plasma metabolites and 14 CSF metabolite biomarkers. These differentiate against healthy individuals with an AUC of 0.8 and 0.9 in PD, respectively. We also identify ten PDD specific serum metabolites, which differentiate against healthy individuals and PD patients without dementia with an AUC of 1.0, respectively. Furthermore, 23 akinetic-rigid specific plasma markers were identified, which differentiate against tremor-dominant PD patients with an AUC of 0.94 and against healthy individuals with an AUC of 0.98. These findings also suggest more severe disease pathology in the akinetic-rigid PD than in tremor dominant PD. In the analysis of MS patient samples a partial least square analysis yielded predictive models for the classification of PPMS and resulted in 20 PPMS specific metabolites. In another MS study unknown changes in human metabolism were identified after administration of the multiple sclerosis drug dimethylfumarate, which is used for the treatment of RRMS. These results allow to describe and understand the hitherto completely unknown mechanism of action of this new drug and to use these findings for the further development of new drugs and targets against RRMS.
In conclusion, these results have the potential for improved diagnosis of these diseases and improvement of mechanistic understandings, as multiple deregulated pathways were identified. Moreover, novel Dimethylfumarate targets can be used to aid drug development and treatment efficiency. Overall, metabolite profiling in combination with machine learning identified as a promising approach for biomarker discovery and mode of action elucidation.
The topic of this thesis is the experimental investigation of evaporating thin films on planar solid substrates and the enrichment, the crystal growth and Marangoni flows near the three phase line in the case of partially wetting mixtures of volatile and non volatile liquids. In short, it deals with the properties of planar liquid films and with those of thin liquid sections near the three phase contact line. In both cases the liquid looses continuously one component by evaporation. One topic is the rupture behavior of ultra-thin films of binary mixtures of a volatile solvent and a nonvolatile solute. It is studied how the thickness at which the film ruptures is related to the solute crystallization at the liquid/ substrate interface as soon as the solute reaches supersaturation. A universal relation between the rupture thickness and the saturation behaviour is presented. The second research subject are individual nanoparticles embedded in molecularly thin films at planar substrates. It is found that the nanoparticles cause an unexpectedly large film surface distortion (meniscus). This distortion can be measured quantitatively by conventional reflective microscopy although the nanoparticles are much smaller than the Rayleigh diffraction limit. Investigations with binary mixtures of volatile solvents and non-volatile solutes (polymers) aim at a better understanding/prediction of the final solute coverage, the timeresolved film thinning, the time-resolved solvent evaporation, and the evolution of the solute concentration within the thinning film. A quantiative theoretical description of the experimental findings is derived. Experiments of completely miscible binary mixtures of volatile liquids, which individually form continuous planar films show unexpectedly that films of mixtures are not necessarily continuous and planar. Rather, they may form surface
undulations or even rupture. This is explained with surface Marangoni flows. A new method for the exceptionally fast fabrication (mm/min) of ultralong aligned diphenylalanin single crystals via dip casting is presented. It is shown how the specific evaporation conditions at the three phase line can be used for a controlled peptide crystal growth process. It is further demonstrated how the confinement inside a smalll capillary affects the peptide crystallization and how this can be understood (and used).