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On Track to Success?
(2022)
Many countries consider expanding vocational curricula in secondary education to boost skills and labour market outcomes among non-university-bound students. However, critics fear this could divert other students from more profitable academic education. We study labour market returns to vocational education in England, where until recently students chose between a vocational track, an academic track and quitting education at age 16. Identification is challenging because self-selection is strong and because students’ next-best alternatives are unknown. Against this back- drop, we leverage multiple instrumental variables to estimate margin-specific treatment effects, i.e., causal returns to vocational education for students at the margin with academic education and, separately, for students at the margin with quitting education. Identification comes from variation in distance to the nearest vocational provider conditional on distance to the nearest academic provider (and vice-versa), while controlling for granular student, school and neighbourhood characteristics. The analysis is based on population-wide administrative education data linked to tax records. We find that the vast majority of marginal vocational students are indifferent be- tween vocational and academic education. For them, vocational enrolment substantially decreases earnings at age 30. This earnings penalty grows with age and is due to wages, not employment. However, consistent with comparative advantage, the penalty is smaller for students with higher revealed preferences for the vocational track. For the few students at the margin with no further education, we find merely tentative evidence of increased employment and earnings from vocational enrolment.
The Arctic is changing rapidly and permafrost is thawing. Especially ice-rich permafrost, such as the late Pleistocene Yedoma, is vulnerable to rapid and deep thaw processes such as surface subsidence after the melting of ground ice. Due to permafrost thaw, the permafrost carbon pool is becoming increasingly accessible to microbes, leading to increased greenhouse gas emissions, which enhances the climate warming.
The assessment of the molecular structure and biodegradability of permafrost organic matter (OM) is highly needed. My research revolves around the question “how does permafrost thaw affect its OM storage?” More specifically, I assessed (1) how molecular biomarkers can be applied to characterize permafrost OM, (2) greenhouse gas production rates from thawing permafrost, and (3) the quality of OM of frozen and (previously) thawed sediments.
I studied deep (max. 55 m) Yedoma and thawed Yedoma permafrost sediments from Yakutia (Sakha Republic). I analyzed sediment cores taken below thermokarst lakes on the Bykovsky Peninsula (southeast of the Lena Delta) and in the Yukechi Alas (Central Yakutia), and headwall samples from the permafrost cliff Sobo-Sise (Lena Delta) and the retrogressive thaw slump Batagay (Yana Uplands). I measured biomarker concentrations of all sediment samples. Furthermore, I carried out incubation experiments to quantify greenhouse gas production in thawing permafrost.
I showed that the biomarker proxies are useful to assess the source of the OM and to distinguish between OM derived from terrestrial higher plants, aquatic plants and microbial activity. In addition, I showed that some proxies help to assess the degree of degradation of permafrost OM, especially when combined with sedimentological data in a multi-proxy approach. The OM of Yedoma is generally better preserved than that of thawed Yedoma sediments. The greenhouse gas production was highest in the permafrost sediments that thawed for the first time, meaning that the frozen Yedoma sediments contained most labile OM. Furthermore, I showed that the methanogenic communities had established in the recently thawed sediments, but not yet in the still-frozen sediments.
My research provided the first molecular biomarker distributions and organic carbon turnover data as well as insights in the state and processes in deep frozen and thawed Yedoma sediments. These findings show the relevance of studying OM in deep permafrost sediments.
Biofilms are complex living materials that form as bacteria get embedded in a matrix of self-produced protein and polysaccharide fibres. The formation of a network of extracellular biopolymer fibres contributes to the cohesion of the biofilm by promoting cell-cell attachment and by mediating biofilm-substrate interactions. This sessile mode of bacteria growth has been well studied by microbiologists to prevent the detrimental effects of biofilms in medical and industrial settings. Indeed, biofilms are associated with increased antibiotic resistance in bacterial infections, and they can also cause clogging of pipelines or promote bio-corrosion. However, biofilms also gained interest from biophysics due to their ability to form complex morphological patterns during growth. Recently, the emerging field of engineered living materials investigates biofilm mechanical properties at multiple length scales and leverages the tools of synthetic biology to tune the functions of their constitutive biopolymers.
This doctoral thesis aims at clarifying how the morphogenesis of Escherichia coli (E. coli) biofilms is influenced by their growth dynamics and mechanical properties. To address this question, I used methods from cell mechanics and materials science. I first studied how biological activity in biofilms gives rise to non-uniform growth patterns. In a second study, I investigated how E. coli biofilm morphogenesis and its mechanical properties adapt to an environmental stimulus, namely the water content of their substrate. Finally, I estimated how the mechanical properties of E. coli biofilms are altered when the bacteria express different extracellular biopolymers.
On nutritive hydrogels, micron-sized E. coli cells can build centimetre-large biofilms. During this process, bacterial proliferation and matrix production introduce mechanical stresses in the biofilm, which release through the formation of macroscopic wrinkles and delaminated buckles. To relate these biological and mechanical phenomena, I used time-lapse fluorescence imaging to track cell and matrix surface densities through the early and late stages of E. coli biofilm growth. Colocalization of high cell and matrix densities at the periphery precede the onset of mechanical instabilities at this annular region. Early growth is detected at this outer annulus, which was analysed by adding fluorescent microspheres to the bacterial inoculum. But only when high rates of matrix production are present in the biofilm centre, does overall biofilm spreading initiate along the solid-air interface. By tracking larger fluorescent particles for a long time, I could distinguish several kinematic stages of E. coli biofilm expansion and observed a transition from non-linear to linear velocity profiles, which precedes the emergence of wrinkles at the biofilm periphery. Decomposing particle velocities to their radial and circumferential components revealed a last kinematic stage, where biofilm movement is mostly directed towards the radial delaminated buckles, which verticalize. The resulting compressive strains computed in these regions were observed to substantially deform the underlying agar substrates. The co-localization of higher cell and matrix densities towards an annular region and the succession of several kinematic stages are thus expected to promote the emergence of mechanical instabilities at the biofilm periphery. These experimental findings are predicted to advance future modelling approaches of biofilm morphogenesis.
E. coli biofilm morphogenesis is further anticipated to depend on external stimuli from the environment. To clarify how the water could be used to tune biofilm material properties, we quantified E. coli biofilm growth, wrinkling dynamics and rigidity as a function of the water content of the nutritive substrates. Time-lapse microscopy and computational image analysis revealed that substrates with high water content promote biofilm spreading kinetics, while substrates with low water content promote biofilm wrinkling. The wrinkles observed on biofilm cross-sections appeared more bent on substrates with high water content, while they tended to be more vertical on substrates with low water content. Both wet and dry biomass, accumulated over 4 days of culture, were larger in biofilms cultured on substrates with high water content, despite extra porosity within the matrix layer. Finally, the micro-indentation analysis revealed that substrates with low water content supported the formation of stiffer biofilms. This study shows that E. coli biofilms respond to the water content of their substrate, which might be used for tuning their material properties in view of further applications.
Biofilm material properties further depend on the composition and structure of the matrix of extracellular proteins and polysaccharides. In particular, E. coli biofilms were suggested to present tissue-like elasticity due to a dense fibre network consisting of amyloid curli and phosphoethanolamine-modified cellulose. To understand the contribution of these components to the emergent mechanical properties of E. coli biofilms, we performed micro-indentation on biofilms grown from bacteria of several strains. Besides showing higher dry masses, larger spreading diameters and slightly reduced water contents, biofilms expressing both main matrix components also presented high rigidities in the range of several hundred kPa, similar to biofilms containing only curli fibres. In contrast, a lack of amyloid curli fibres provides much higher adhesive energies and more viscoelastic fluid-like material behaviour. Therefore, the combination of amyloid curli and phosphoethanolamine-modified cellulose fibres implies the formation of a composite material whereby the amyloid curli fibres provide rigidity to E. coli biofilms, whereas the phosphoethanolamine-modified cellulose rather acts as a glue. These findings motivate further studies involving purified versions of these protein and polysaccharide components to better understand how their interactions benefit biofilm functions.
All three studies depict different aspects of biofilm morphogenesis, which are interrelated. The first work reveals the correlation between non-uniform biological activities and the emergence of mechanical instabilities in the biofilm. The second work acknowledges the adaptive nature of E. coli biofilm morphogenesis and its mechanical properties to an environmental stimulus, namely water. Finally, the last study reveals the complementary role of the individual matrix components in the formation of a stable biofilm material, which not only forms complex morphologies but also functions as a protective shield for the bacteria it contains. Our experimental findings on E. coli biofilm morphogenesis and their mechanical properties can have further implications for fundamental and applied biofilm research fields.
Schulpraktika bilden die zentrale Grundlage der Lehrerbildung in Potsdam. Bereits im Potsdamer Modell der Lehrerbildung (1993) sind sie festgehalten, seit der Integration des Schulpraktikums (Praxissemesters) 2008 absolvieren alle Potsdamer Lehramtsstudierenden fünf Pflichtpraktika. Während die Ziele der Praktika klar beschrieben sind, sind die tatsächlichen Lernerfolge nicht immer klar – ebenso wenig, wie die Begleitung der Praktika aussehen muss, um die Studierenden bestmöglich zu unterstützen. Auch die Integration in weitere Lehrveranstaltungen des Studiums ist ein noch offenes Feld, das weiterer Betrachtung verdient. Die unterschiedliche Ausrichtung der Potsdamer Praktika, Perspektivwechsel im Orientierungs-/Integriertem Eingangspraktikum, Selbstreflektion im Praktikum in pädagogisch-psychologischen Handlungsfeldern, Unterricht als Profession in den Fachdidaktischen Tagespraktika, Anwendung von Diagnostik im psychodiagnostischen Praktikum und die Synthese all dessen im Schulpraktikum, bieten dafür zahlreiche Ansatzpunkte.
Schulpraktika sind nicht nur ein zentraler und von Studierenden hoch geschätzter Bestandteil des Studiums, sondern werden auch zunehmend für die Bildungsforschung interessant. Fragen nach der Kompetenzentwicklung, Selbsteinschätzungen und der Entwicklung der Reflexionsfähigkeit von Studierenden stehen dabei ebenso im Fokus wie die Einschätzung der universitären Begleitung und der Einbindung ins weitere Studium.
Der vorliegende Band versammelt Studien von Wissenschaftlerinnen und Wissenschaftler der Universität Potsdam, die die fünf Pflichtpraktika im Lehramtsstudium unter unterschiedlichen Blickwinkel beforschen. Besonders hervorzuheben ist, dass die Wissenschaftlerinnen und Wissenschaftler aus unterschiedlichen Disziplinen stammen und somit die Praktika mit verschiedenen Instrumenten und aus unterschiedlichen Blickwinkeln betrachten. Die präsentierten Ergebnisse bilden eine gute Grundlage, um die Praktika in Potsdam und an anderen Standorten weiterzuentwickeln.
We demonstrate how the incentives of firms that partially own their suppliers or customers to foreclose rivals depend on how the partial owner can extract profits from the target (tunneling). Compared to a fully vertically integrated firm, a partial owner may obtain only a share of the target’s profit but influence the target’s strategy significantly. We show that the incentives for customer and input foreclosure can be higher, equal, or even lower with partial ownership than with a vertical merger, depending on how the protection of minority shareholders and transfer price regulations affect the scope for profit extraction.
The self-employed faced strong income losses during the Covid-19 pandemic. Many governments introduced programs to financially support the self-employed during the pandemic, including Germany. The German Ministry for Economic Affairs announced a €50bn emergency-aid program in March 2020, offering one-off lump-sum payments of up to €15,000 to those facing substantial revenue declines. By reassuring the self- employed that the government ‘would not let them down’ during the crisis, the program had also the important aim of motivating the self-employed to get through the crisis. We investigate whether the program affected the confidence of the self-employed to survive the crisis using real-time online-survey data comprising more than 20,000 observations. We employ propensity score matching, making use of a rich set of variables that influence the subjective survival probability as main outcome measure. We observe that this program had significant effects, with the subjective survival probability of the self- employed being moderately increased. We reveal important effect heterogeneities with respect to education, industries, and speed of payment. Notably, positive effects only occur among those self-employed whose application was processed quickly. This suggests stress-induced waiting costs due to the uncertainty associated with the administrative processing and the overall pandemic situation. Our findings have policy implications for the design of support programs, while also contributing to the literature on the instruments and effects of entrepreneurship policy interventions in crisis situations.
Kaum einem anderen Unterrichtsfach ist das Fachübergreifende so immanent wie dem Fach Musik, das durch seine Themen- und Inhaltsfelder vielfältige Bezüge zu anderen Fächern und Wissenschaftsdisziplinen aufweist. Dennoch lässt sich bezüglich der Literatur- und Forschungslage konstatieren, dass zwar theoretische Ansätze und Modelle für einen fachübergreifenden Musikunterricht existieren, sich die musikpädagogische Forschung jedoch mit dem fachübergreifenden Musikunterricht und dessen Umsetzung durch die Musiklehrkräfte noch nicht befasst hat. Auch die Zahl der praxisbezogenen Publikationen für einen fachübergreifenden Musikunterricht ist überschaubar, ebenso das Fortbildungsangebot für Musiklehrende.
Aus diesem Grund widmet sich der vorliegende Band 9 der „Potsdamer Schriftenreihe zur Musikpädagogik“ dem Thema „Fachübergreifender Musikunterricht“ aus verschiedenen Perspektiven. Zum einen bilden die derzeit aktuellen theoretischen Grundlagen eine wichtige Basis. Zum anderen fließen auch ausbildungsrelevante und methodische Aspekte zur Umsetzung eines fachübergreifenden Musikunterrichts in die Texte ein. In bewährter Tradition der Schriftenreihe werden dabei sowohl Beiträge von Lehrenden am Lehrstuhl für Musikpädagogik und Musikdidaktik der Universität Potsdam als auch von Studierenden sowie von Kooperationspartnern des Lehrstuhls in der Musiklehrer*innenbildung berücksichtigt. Ziel ist es, auf der Basis verschiedener theoretischer Ansätze Umsetzungsmöglichkeiten eines fachübergreifenden Musikunterrichts als Beitrag zum Erreichen der im Teil B des Rahmenlehrplans für Berlin und Brandenburg angeführten fachübergreifenden Kompetenzziele aufzuzeigen.
Strategic uncertainty is the uncertainty that players face with respect to the purposeful behavior of other players in an interactive decision situation. Our paper develops a new method for measuring strategic-uncertainty attitudes and distinguishing them from risk and ambiguity attitudes. We vary the source of uncertainty (whether strategic or not) across conditions in a ceteris paribus manner. We elicit certainty equivalents of participating in two strategic 2x2 games (a stag-hunt and a market-entry game) as well as certainty equivalents of related lotteries that yield the same possible payoffs with exogenously given probabilities (risk) and lotteries with unknown probabilities (ambiguity). We provide a structural model of uncertainty attitudes that allows us to measure a preference for or an aversion against the source of uncertainty, as well as optimism or pessimism regarding the desired outcome. We document systematic attitudes towards strategic uncertainty that vary across contexts. Under strategic complementarity [substitutability], the majority of participants tend to be pessimistic [optimistic] regarding the desired outcome. However, preferences for the source of uncertainty are distributed around zero.
Property tax competition
(2022)
We develop a model of property taxation and characterize equilibria under three alternative taxa-tion regimes often used in the public finance literature: decentralized taxation, centralized taxation, and “rent seeking” regimes. We show that decentralized taxation results in inefficiently high tax rates, whereas centralized taxation yields a common optimal tax rate, and tax rates in the rent-seeking regime can be either inefficiently high or low. We quantify the effects of switching from the observed tax system to the three regimes for Japan and Germany. The decentralized or rent-seeking regime best describes the Japanese tax system, whereas the centralized regime does so for Germany. We also quantify the welfare effects of regime changes.
This paper sheds new light on the role of communication for cartel formation. Using machine learning to evaluate free-form chat communication among firms in a laboratory experiment, we identify typical communication patterns for both explicit cartel formation and indirect attempts to collude tacitly. We document that firms are less likely to communicate explicitly about price fixing and more likely to use indirect messages when sanctioning institutions are present. This effect of sanctions on communication reinforces the direct cartel-deterring effect of sanctions as collusion is more difficult to reach and sustain without an explicit agreement. Indirect messages have no, or even a negative, effect on prices.
In the present thesis I investigate the lattice dynamics of thin film hetero structures of magnetically ordered materials upon femtosecond laser excitation as a probing and manipulation scheme for the spin system. The quantitative assessment of laser induced thermal dynamics as well as generated picosecond acoustic pulses and their respective impact on the magnetization dynamics of thin films is a challenging endeavor. All the more, the development and implementation of effective experimental tools and comprehensive models are paramount to propel future academic and technological progress.
In all experiments in the scope of this cumulative dissertation, I examine the crystal lattice of nanoscale thin films upon the excitation with femtosecond laser pulses. The relative change of the lattice constant due to thermal expansion or picosecond strain pulses is directly monitored by an ultrafast X-ray diffraction (UXRD) setup with a femtosecond laser-driven plasma X-ray source (PXS). Phonons and spins alike exert stress on the lattice, which responds according to the elastic properties of the material, rendering the lattice a versatile sensor for all sorts of ultrafast interactions. On the one hand, I investigate materials with strong magneto-elastic properties; The highly magnetostrictive rare-earth compound TbFe2, elemental Dysprosium or the technological relevant Invar material FePt. On the other hand I conduct a comprehensive study on the lattice dynamics of Bi1Y2Fe5O12 (Bi:YIG), which exhibits high-frequency coherent spin dynamics upon femtosecond laser excitation according to the literature. Higher order standing spinwaves (SSWs) are triggered by coherent and incoherent motion of atoms, in other words phonons, which I quantified with UXRD. We are able to unite the experimental observations of the lattice and magnetization dynamics qualitatively and quantitatively. This is done with a combination of multi-temperature, elastic, magneto-elastic, anisotropy and micro-magnetic modeling.
The collective data from UXRD, to probe the lattice, and time-resolved magneto-optical Kerr effect (tr-MOKE) measurements, to monitor the magnetization, were previously collected at different experimental setups. To improve the precision of the quantitative assessment of lattice and magnetization dynamics alike, our group implemented a combination of UXRD and tr-MOKE in a singular experimental setup, which is to my knowledge, the first of its kind. I helped with the conception and commissioning of this novel experimental station, which allows the simultaneous observation of lattice and magnetization dynamics on an ultrafast timescale under identical excitation conditions. Furthermore, I developed a new X-ray diffraction measurement routine which significantly reduces the measurement time of UXRD experiments by up to an order of magnitude. It is called reciprocal space slicing (RSS) and utilizes an area detector to monitor the angular motion of X-ray diffraction peaks, which is associated with lattice constant changes, without a time-consuming scan of the diffraction angles with the goniometer. RSS is particularly useful for ultrafast diffraction experiments, since measurement time at large scale facilities like synchrotrons and free electron lasers is a scarce and expensive resource. However, RSS is not limited to ultrafast experiments and can even be extended to other diffraction techniques with neutrons or electrons.
One aspect of achieving a more sustainable chemical industry is the minimization of the usage of solvents and chemicals. Thus, optimization and development of chemical processes for large-scale production is favourably performed in small batches. The critical step in this approach is upscaling the batches from the small reaction systems to the large reactors mandatory for cost efficient production in an industrial environment. Scaling up the bulk volume always goes along with increasing the surface where the reaction medium is in contact with the confining vessel. Since volume scales proportional with the cubic dimension while the surface scales quadratic, their ratio is size-dependent. The influence of reaction vessel walls can change the reaction performance. A number of phenomena occurring at the surface-liquid interface can affect reaction rates and yields, resulting in possible difficulties in predicting and extrapolating from small size production scale to large industrial processes. The application of levitated droplets as a containerless reaction vessels provides a promising possibility to avoid the above-mentioned issues.
In the presented work, an efficient coupling of acoustically levitated droplets to an ion mobility (IM) spectrometer, operating at ambient conditions, was designed for real-time monitoring of chemical reactions. The design of the system comprises noncontact sampling and ionization of the droplet realised by laser desorption/ionization at 2,94 µm. The scope of the work includes fundamental studies covering understanding of laser irradiation of droplets enclosed in an acoustical field. Understanding of this phenomenon is crucial to comprehending the effects of temporal and spatial resolution of the generated ion plume that influence the resolution of the system.
The set-up includes an acoustic trap, laser irradiation and ion manipulation electrostatic lenses operating at high voltage at ambient pressure. The complexity of the design needs to fully be considered for an effective ion transfer at the interface region between the levitated droplet and IM spectrometer. For sampling and ionization, two distinct laser pulse lengths were evaluated, ns and µs. Irradiation via µs laser pulses provides several advantages: i) the droplet volume is not extensively impinged, as in case of ns laser pulses, allowing the sampling of only the small volume of the droplet; ii) the lower fluence results in less pronounced oscillations of the droplet confined in the acoustic field. The droplet will not be dissipated out of the acoustic field leading to loss of the sample; iii) the mild laser irradiation results in better spatial and temporal ion plume confinement, leading to better resolution of the detected ion packets. Finally, this knowledge allows the application of ion optics necessary to induce ion flow between the droplet suspended in the acoustic field and the IM spectrometer. The ion optics, composed of 2 electrostatic lenses placed in the near vicinity of the droplet, allow effective focusing of the ion plume and its redirection directly to the IM spectrometer entrance. This novel coupling has proved to be successful for detection of some simple molecules ionizable at the 2.94 µm wavelength. To further demonstrate the applicability of the system, a proof-of-principle reaction was selected, fulfilling the requirements of the system, and was subjected to comprehensive investigation of its performance. Herein, the reaction between N-Boc cysteine methyl ester and allyl alcohol has been performed in a batch reactor and on-line monitored via 1H NMR to establish reaction propagation. With the additional assessment, it was confirmed that the thiol-ene coupling can be performed within first 20 minutes of the irradiation with a reaction yield above 50%, proving that the reaction can be applied as a study case to assess the possibilities of the developed system.
What are the consequences of unemployment and precarious employment for individuals' health in Europe? What are the moderating factors that may offset (or increase) the health consequences of labor-market risks? How do the effects of these risks vary across different contexts, which differ in their institutional and cultural settings? Does gender, regarded as a social structure, play a role, and how? To answer these questions is the aim of my cumulative thesis. This study aims to advance our knowledge about the health consequences that unemployment and precariousness cause over the life course. In particular, I investigate how several moderating factors, such as gender, the family, and the broader cultural and institutional context, may offset or increase the impact of employment instability and insecurity on individual health.
In my first paper, 'The buffering role of the family in the relationship between job loss and self-perceived health: Longitudinal results from Europe, 2004-2011', I and my co-authors measure the causal effect of job loss on health and the role of the family and welfare states (regimes) as moderating factors. Using EU-SILC longitudinal data (2004-2011), we estimate the probability of experiencing 'bad health' following a transition to unemployment by applying linear probability models and undertake separate analyses for men and women. Firstly, we measure whether changes in the independent variable 'job loss' lead to changes in the dependent variable 'self-rated health' for men and women separately. Then, by adding into the model different interaction terms, we measure the moderating effect of the family, both in terms of emotional and economic support, and how much it varies across different welfare regimes. As an identification strategy, we first implement static fixed-effect panel models, which control for time-varying observables and indirect health selection—i.e., constant unobserved heterogeneity. Secondly, to control for reverse causality and path dependency, we implement dynamic fixed-effect panel models, adding a lagged dependent variable to the model.
We explore the role of the family by focusing on close ties within households: we consider the presence of a stable partner and his/her working status as a source of social and economic support. According to previous literature, having a partner should reduce the stress from adverse events, thanks to the symbolic and emotional dimensions that such a relationship entails, regardless of any economic benefits. Our results, however, suggest that benefits linked to the presence of a (female) partner also come from the financial stability that (s)he can provide in terms of a second income. Furthermore, we find partners' employment to be at least as important as the mere presence of the partner in reducing the negative effect of job loss on the individual's health by maintaining the household's standard of living and decreasing economic strain on the family. Our results are in line with previous research, which has highlighted that some people cope better than others with adverse life circumstances, and the support provided by the family is a crucial resource in that regard.
We also reported an important interaction between the family and the welfare state in moderating the health consequences of unemployment, showing how the compensation effect of the family varies across welfare regimes. The family plays a decisive role in cushioning the adverse consequences of labor market risks in Southern and Eastern welfare states, characterized by less developed social protection systems and –especially the Southern – high level of familialism.
The first paper also found important gender differences concerning job loss, family and welfare effects. Of particular interest is the evidence suggesting that health selection works differently for men and women, playing a more prominent role for women than for men in explaining the relationship between job loss and self-perceived health. The second paper, 'Gender roles and selection mechanisms across contexts: A comparative analysis of the relationship between unemployment, self-perceived health, and gender.' investigates more in-depth the gender differential in health driven by unemployment.
Being a highly contested issue in literature, we aim to study whether men are more penalized than women or the other way around and the mechanisms that may explain the gender difference. To do that, we rely on two theoretical arguments: the availability of alternative roles and social selection. The first argument builds on the idea that men and women may compensate for the detrimental health consequences of unemployment through the commitment to 'alternative roles,' which can provide for the resources needed to fulfill people's socially constructed needs. Notably, the availability of alternative options depends on the different positions that men and women have in society.
Further, we merge the availability of the 'alternative roles' argument with the health selection argument. We assume that health selection could be contingent on people's social position as defined by gender and, thus, explain the gender differential in the relationship between unemployment and health. Ill people might be less reluctant to fall or remain (i.e., self-select) in unemployment if they have alternative roles. In Western societies, women generally have more alternative roles than men and thus more discretion in their labor market attachment. Therefore, health selection should be stronger for them, explaining why unemployment is less menace for women than for their male counterparts.
Finally, relying on the idea of different gender regimes, we extended these arguments to comparison across contexts. For example, in contexts where being a caregiver is assumed to be women's traditional and primary roles and the primary breadwinner role is reserved to men, unemployment is less stigmatized, and taking up alternative roles is more socially accepted for women than for men (Hp.1). Accordingly, social (self)selection should be stronger for women than for men in traditional contexts, where, in the case of ill-health, the separation from work is eased by the availability of alternative roles (Hp.2).
By focusing on contexts that are representative of different gender regimes, we implement a multiple-step comparative approach. Firstly, by using EU-SILC longitudinal data (2004-2015), our analysis tests gender roles and selection mechanisms for Sweden and Italy, representing radically different gender regimes, thus providing institutional and cultural variation. Then, we limit institutional heterogeneity by focusing on Germany and comparing East- and West-Germany and older and younger cohorts—for West-Germany (SOEP data 1995-2017). Next, to assess the differential impact of unemployment for men and women, we compared (unemployed and employed) men with (unemployed and employed) women. To do so, we calculate predicted probabilities and average marginal effect from two distinct random-effects probit models. Our first step is estimating random-effects models that assess the association between unemployment and self-perceived health, controlling for observable characteristics. In the second step, our fully adjusted model controls for both direct and indirect selection. We do this using dynamic correlated random-effects (CRE) models. Further, based on the fully adjusted model, we test our hypotheses on alternative roles (Hp.1) by comparing several contexts – models are estimated separately for each context. For this hypothesis, we pool men and women and include an interaction term between unemployment and gender, which has the advantage to allow for directly testing whether gender differences in the effect of unemployment exist and are statistically significant. Finally, we test the role of selection mechanisms (Hp.2), using the KHB method to compare coefficients across nested nonlinear models. Specifically, we test the role of selection for the relationship between unemployment and health by comparing the partially-adjusted and fully-adjusted models. To allow selection mechanisms to operate differently between genders, we estimate separate models for men and women.
We found support to our first hypotheses—the context where people are embedded structures the relationship between unemployment, health, and gender. We found no gendered effect of unemployment on health in the egalitarian context of Sweden. Conversely, in the traditional context of Italy, we observed substantive and statistically significant gender differences in the effect of unemployment on bad health, with women suffering less than men. We found the same pattern for comparing East and West Germany and younger and older cohorts in West Germany.
On the contrary, our results did not support our theoretical argument on social selection. We found that in Sweden, women are more selected out of employment than men. In contrast, in Italy, health selection does not seem to be the primary mechanism behind the gender differential—Italian men and women seem to be selected out of employment to the same extent. Namely, we do not find any evidence that health selection is stronger for women in more traditional countries (Hp2), despite the fact that the institutional and the cultural context would offer them a more comprehensive range of 'alternative roles' relative to men. Moreover, our second hypothesis is also rejected in the second and third comparisons, where the cross-country heterogeneity is reduced to maximize cultural differences within the same institutional context. Further research that addresses selection into inactivity is needed to evaluate the interplay between selection and social roles across gender regimes.
While the health consequences of unemployment have been on the research agenda for a pretty long time, the interest in precarious employment—defined as the linking of the vulnerable worker to work that is characterized by uncertainty and insecurity concerning pay, the stability of the work arrangement, limited access to social benefits, and statutory protections—has emerged only later. Since the 80s, scholars from different disciplines have raised concerns about the social consequences of de-standardization of employment relationships. However, while work has become undoubtedly more precarious, very little is known about its causal effect on individual health and the role of gender as a moderator. These questions are at the core of my third paper : 'Bad job, bad health? A longitudinal analysis of the interaction between precariousness, gender and self-perceived health in Germany'. Herein, I investigate the multidimensional nature of precarious employment and its causal effect on health, particularly focusing on gender differences.
With this paper, I aim at overcoming three major shortcomings of earlier studies: The first one regards the cross-sectional nature of data that prevents the authors from ruling out unobserved heterogeneity as a mechanism for the association between precarious employment and health. Indeed, several unmeasured individual characteristics—such as cognitive abilities—may confound the relationship between precarious work and health, leading to biased results. Secondly, only a few studies have directly addressed the role of gender in shaping the relationship. Moreover, available results on the gender differential are mixed and inconsistent: some found precarious employment being more detrimental for women's health, while others found no gender differences or stronger negative association for men. Finally, previous attempts to an empirical translation of the employment precariousness (EP) concept have not always been coherent with their theoretical framework. EP is usually assumed to be a multidimensional and continuous phenomenon; it is characterized by different dimensions of insecurity that may overlap in the same job and lead to different "degrees of precariousness." However, researchers have predominantly focused on one-dimensional indicators—e.g., temporary employment, subjective job insecurity—to measure EP and study the association with health. Besides the fact that this approach partially grasps the phenomenon's complexity, the major problem is the inconsistency of evidence that it has produced. Indeed, this line of inquiry generally reveals an ambiguous picture, with some studies finding substantial adverse effects of temporary over permanent employment, while others report only minor differences.
To measure the (causal) effect of precarious work on self-rated health and its variation by gender, I focus on Germany and use four waves from SOEP data (2003, 2007, 2011, and 2015). Germany is a suitable context for my study. Indeed, since the 1980s, the labor market and welfare system have been restructured in many ways to increase the German economy's competitiveness in the global market. As a result, the (standard) employment relationship has been de-standardized: non-standard and atypical employment arrangements—i.e., part-time work, fixed-term contracts, mini-jobs, and work agencies—have increased over time while wages have lowered, even among workers with standard work. In addition, the power of unions has also fallen over the last three decades, leaving a large share of workers without collective protection. Because of this process of de-standardization, the link between wage employment and strong social rights has eroded, making workers more powerless and more vulnerable to labor market risks than in the past. EP refers to this uneven distribution of power in the employment relationship, which can be detrimental to workers' health. Indeed, by affecting individuals' access to power and other resources, EP puts precarious workers at risk of experiencing health shocks and influences their ability to gain and accumulate health advantages (Hp.1).
Further, the focus on Germany allows me to investigate my second research question on the gender differential. Germany is usually regarded as a traditionalist gender regime: a context characterized by a configuration of roles. Here, being a caregiver is assumed to be women's primary role, whereas the primary breadwinner role is reserved for men. Although many signs of progress have been made over the last decades towards a greater equalization of opportunities and more egalitarianism, the breadwinner model has barely changed towards a modified version. Thus, women usually take on the double role of workers (the so-called secondary earner) and caregivers, and men still devote most of their time to paid work activities. Moreover, the overall upward trend towards more egalitarian gender ideologies has leveled off over the last decades, moving notably towards more traditional gender ideologies.
In this setting, two alternative hypotheses are possible. Firstly, I assume that the negative relationship between EP and health is stronger for women than for men. This is because women are systematically more disadvantaged than men in the public and private spheres of life, having less access to formal and informal sources of power. These gender-related power asymmetries may interact with EP-related power asymmetries resulting in a stronger effect of EP on women's health than on men's health (Hp.2).
An alternative way of looking at the gender differential is to consider the interaction that precariousness might have with men's and women's gender identities. According to this view, the negative relationship between EP and health is weaker for women than for men (Hp.2a). In a society with a gendered division of labor and a strong link between masculine identities and stable and well-rewarded job—i.e., a job that confers the role of primary family provider—a male worker with precarious employment might violate the traditional male gender role. Men in precarious jobs may perceive themselves (and by others) as possessing a socially undesirable characteristic, which conflicts with the stereotypical idea of themselves as the male breadwinner. Engaging in behaviors that contradict stereotypical gender identity may decrease self-esteem and foster feelings of inferiority, helplessness, and jealousy, leading to poor health.
I develop a new indicator of EP that empirically translates a definition of EP as a multidimensional and continuous phenomenon. I assume that EP is a latent construct composed of seven dimensions of insecurity chosen according to the theory and previous empirical research: Income insecurity, social insecurity, legal insecurity, employment insecurity, working-time insecurity, representation insecurity, worker's vulnerability. The seven dimensions are proxied by eight indicators available in the four waves of the SOEP dataset. The EP composite indicator is obtained by performing a multiple correspondence analysis (MCA) on the eight indicators. This approach aims to construct a summary scale in which all dimensions contribute jointly to the measured experience of precariousness and its health impact.
Further, the relationship between EP and 'general self-perceived health' is estimated by applying ordered probit random-effects estimators and calculating average marginal effect (further AME). Then, to control for unobserved heterogeneity, I implement correlated random-effects models that add to the model the within-individual means of the time-varying independent variables. To test the significance of the gender differential, I add an interaction term between EP and gender in the fully adjusted model in the pooled sample.
My correlated random-effects models showed EP's negative and substantial 'effect' on self-perceived health for both men and women. Although nonsignificant, the evidence seems in line with previous cross-sectional literature. It supports the hypothesis that employment precariousness could be detrimental to workers' health. Further, my results showed the crucial role of unobserved heterogeneity in shaping the health consequences of precarious employment. This is particularly important as evidence accumulates, yet it is still mostly descriptive.
Moreover, my results revealed a substantial difference among men and women in the relationship between EP and health: when EP increases, the risk of experiencing poor health increases much more for men than for women. This evidence falsifies previous theory according to whom the gender differential is contingent on the structurally disadvantaged position of women in western societies. In contrast, they seem to confirm the idea that men in precarious work could experience role conflict to a larger extent than women, as their self-standard is supposed to be the stereotypical breadwinner worker with a good and well-rewarded job. Finally, results from the multiple correspondence analysis contribute to the methodological debate on precariousness, showing that a multidimensional and continuous indicator can express a latent variable of EP.
All in all, complementarities are revealed in the results of unemployment and employment precariousness, which have two implications: Policy-makers need to be aware that the total costs of unemployment and precariousness go far beyond the economic and material realm penetrating other fundamental life domains such as individual health. Moreover, they need to balance the trade-off between protecting adequately unemployed people and fostering high-quality employment in reaction to the highlighted market pressures. In this sense, the further development of a (universalistic) welfare state certainly helps mitigate the adverse health effects of unemployment and, therefore, the future costs of both individuals' health and welfare spending. In addition, the presence of a working partner is crucial for reducing the health consequences of employment instability. Therefore, policies aiming to increase female labor market participation should be promoted, especially in those contexts where the welfare state is less developed.
Moreover, my results support the significance of taking account of a gender perspective in health research. The findings of the three articles show that job loss, unemployment, and precarious employment, in general, have adverse effects on men's health but less or absent consequences for women's health. Indeed, this suggests the importance of labor and health policies that consider and further distinguish the specific needs of the male and female labor force in Europe. Nevertheless, a further implication emerges: the health consequences of employment instability and de-standardization need to be investigated in light of the gender arrangements and the transforming gender relationships in specific cultural and institutional contexts. My results indeed seem to suggest that women's health advantage may be a transitory phenomenon, contingent on the predominant gendered institutional and cultural context. As the structural difference between men's and women's position in society is eroded, egalitarianism becomes the dominant normative status, so will probably be the gender difference in the health consequences of job loss and precariousness. Therefore, while gender equality in opportunities and roles is a desirable aspect for contemporary societies and a political goal that cannot be postponed further, this thesis raises a further and maybe more crucial question: What kind of equality should be pursued to provide men and women with both good life quality and equal chances in the public and private spheres? In this sense, I believe that social and labor policies aiming to reduce gender inequality in society should focus on improving women's integration into the labor market, implementing policies targeting men, and facilitating their involvement in the private sphere of life. Equal redistribution of social roles could activate a crucial transformation of gender roles and the cultural models that sustain and still legitimate gender inequality in Western societies.
Technological progress allows for producing ever more complex predictive models on the basis of increasingly big datasets. For risk management of natural hazards, a multitude of models is needed as basis for decision-making, e.g. in the evaluation of observational data, for the prediction of hazard scenarios, or for statistical estimates of expected damage. The question arises, how modern modelling approaches like machine learning or data-mining can be meaningfully deployed in this thematic field. In addition, with respect to data availability and accessibility, the trend is towards open data. Topic of this thesis is therefore to investigate the possibilities and limitations of machine learning and open geospatial data in the field of flood risk modelling in the broad sense. As this overarching topic is broad in scope, individual relevant aspects are identified and inspected in detail.
A prominent data source in the flood context is satellite-based mapping of inundated areas, for example made openly available by the Copernicus service of the European Union. Great expectations are directed towards these products in scientific literature, both for acute support of relief forces during emergency response action, and for modelling via hydrodynamic models or for damage estimation. Therefore, a focus of this work was set on evaluating these flood masks. From the observation that the quality of these products is insufficient in forested and built-up areas, a procedure for subsequent improvement via machine learning was developed. This procedure is based on a classification algorithm that only requires training data from a particular class to be predicted, in this specific case data of flooded areas, but not of the negative class (dry areas). The application for hurricane Harvey in Houston shows the high potential of this method, which depends on the quality of the initial flood mask.
Next, it is investigated how much the predicted statistical risk from a process-based model chain is dependent on implemented physical process details. Thereby it is demonstrated what a risk study based on established models can deliver. Even for fluvial flooding, such model chains are already quite complex, though, and are hardly available for compound or cascading events comprising torrential rainfall, flash floods, and other processes. In the fourth chapter of this thesis it is therefore tested whether machine learning based on comprehensive damage data can offer a more direct path towards damage modelling, that avoids explicit conception of such a model chain. For that purpose, a state-collected dataset of damaged buildings from the severe El Niño event 2017 in Peru is used. In this context, the possibilities of data-mining for extracting process knowledge are explored as well. It can be shown that various openly available geodata sources contain useful information for flood hazard and damage modelling for complex events, e.g. satellite-based rainfall measurements, topographic and hydrographic information, mapped settlement areas, as well as indicators from spectral data. Further, insights on damaging processes are discovered, which mainly are in line with prior expectations. The maximum intensity of rainfall, for example, acts stronger in cities and steep canyons, while the sum of rain was found more informative in low-lying river catchments and forested areas. Rural areas of Peru exhibited higher vulnerability in the presented study compared to urban areas. However, the general limitations of the methods and the dependence on specific datasets and algorithms also become obvious.
In the overarching discussion, the different methods – process-based modelling, predictive machine learning, and data-mining – are evaluated with respect to the overall research questions. In the case of hazard observation it seems that a focus on novel algorithms makes sense for future research. In the subtopic of hazard modelling, especially for river floods, the improvement of physical models and the integration of process-based and statistical procedures is suggested. For damage modelling the large and representative datasets necessary for the broad application of machine learning are still lacking. Therefore, the improvement of the data basis in the field of damage is currently regarded as more important than the selection of algorithms.
Localisation of deformation is a ubiquitous feature in continental rift dynamics and observed across drastically different time and length scales. This thesis comprises one experimental and two numerical modelling studies investigating strain localisation in (1) a ductile shear zone induced by a material heterogeneity and (2) in an active continental rift setting. The studies are related by the fact that the weakening mechanisms on the crystallographic and grain size scale enable bulk rock weakening, which fundamentally enables the formation of shear zones, continental rifts and hence plate tectonics. Aiming to investigate the controlling mechanisms on initiation and evolution of a shear zone, the torsion experiments of the experimental study were conducted in a Patterson type apparatus with strong Carrara marble cylinders with a weak, planar Solnhofen limestone inclusion. Using state-of-the-art numerical modelling software, the torsion experiments were simulated to answer questions regarding localisation procedure like stress distribution or the impact of rheological weakening. 2D numerical models were also employed to integrate geophysical and geological data to explain characteristic tectonic evolution of the Southern and Central Kenya Rift. Key elements of the numerical tools are a randomized initial strain distribution and the usage of strain softening. During the torsion experiments, deformation begins to localise at the limestone inclusion tips in a process zone, which propagates into the marble matrix with increasing deformation until a ductile shear zone is established. Minor indicators for coexisting brittle deformation are found close to the inclusion tip and presumed to slightly facilitate strain localisation besides the dominant ductile deformation processes. The 2D numerical model of the torsion experiment successfully predicts local stress concentration and strain rate amplification ahead of the inclusion in first order agreement with the experimental results. A simple linear parametrization of strain weaking enables high accuracy reproduction of phenomenological aspects of the observed weakening. The torsion experiments suggest that loading conditions do not affect strain localisation during high temperature deformation of multiphase material with high viscosity contrasts. A numerical simulation can provide a way of analysing the process zone evolution virtually and extend the examinable frame. Furthermore, the nested structure and anastomosing shape of an ultramylonite band was mimicked with an additional second softening step. Rheological weakening is necessary to establish a shear zone in a strong matrix around a weak inclusion and for ultramylonite formation.
Such strain weakening laws are also incorporated into the numerical models of the
Southern and Central Kenya Rift that capture the characteristic tectonic evolution. A three-stage early rift evolution is suggested that starts with (1) the accommodation of strain by a single border fault and flexure of the hanging-wall crust, after which (2) faulting in the hanging-wall and the basin centre increases before (3) the early-stage asymmetry is lost and basinward localisation of deformation occurs. Along-strike variability of rifts can be produced by modifying the initial random noise distribution. In summary, the three studies address selected aspects of the broad range of mechanisms and processes that fundamentally enable the deformation of rock and govern the localisation patterns across the scales. In addition to the aforementioned results, the first and second manuscripts combined, demonstrate a procedure to find new or improve on existing numerical formulations for specific rheologies and their dynamic weakening. These formulations are essential in addressing rock deformation from the grain to the global scale. As within the third study of this thesis, where geodynamic controls on the evolution of a rift were examined and acquired by the integration of geological and geophysical data into a numerical model.
The development of novel programmable materials aiming to control friction in real-time holds potential to facilitate innovative lubrication solutions for reducing wear and energy losses. This work describes the integration of light-responsiveness into two lubricating materials, silicon oils and polymer brush surfaces.
The first part focusses on the assessment on 9-anthracene ester-terminated polydimethylsiloxanes (PDMS-A) and, in particular, on the variability of rheological properties and the implications that arise with UV-light as external trigger. The applied rheometer setup contains an UV-transparent quartz-plate, which enables radiation and simultaneous measurement of the dynamic moduli. UV-A radiation (354 nm) triggers the cycloaddition reaction between the terminal functionalities of linear PDMS, resulting in chain extension. The newly-formed anthracene dimers cleave by UV-C radiation (254 nm) or at elevated temperatures (T > 130 °C). The sequential UV-A radiation and thermal reprogramming over three cycles demonstrate high conversions and reproducible programming of rheological properties. In contrast, the photochemical back reaction by UV-C is incomplete and can only partially restore the initial rheological properties. The dynamic moduli increase with each cycle in photochemical programming, presumably resulting from a chain segment re-arrangement as a result of the repeated partial photocleavage and subsequent chain length-dependent dimerization. In addition, long periods of radiation cause photooxidative degradation, which damages photo-responsive functions and consequently reduces the programming range. The absence of oxygen, however, reduces undesired side reactions. Anthracene-functionalized PDMS and native PDMS mix depending on the anthracene ester content and chain length, respectively, and allow fine-tuning of programmable rheological properties. The work shows the influence of mixing conditions during the photoprogramming step on the rheological properties, indicating that material property gradients induced by light attenuation along the beam have to be considered. Accordingly, thin lubricant films are suggested as potential application for light-programmable silicon fluids.
The second part compares strategies for the grafting of spiropyran (SP) containing copolymer brushes from Si wafers and evaluates the light-responsiveness of the surfaces. Pre-experiments on the kinetics of the thermally initiated RAFT copolymerization of 2-hydroxyethyl acrylate (HEA) and spiropyran acrylate (SPA) in solution show, first, a strong retardation by SP and, second, the dependence of SPA polymerization on light. Surprisingly, the copolymerization of SPA is inhibited in the dark. These findings contribute to improve the synthesis of polar, spiropyran-containing copolymers. The comparison between initiator systems for the grafting-from approach indicates PET-RAFT superior to thermally initiated RAFT, suggesting a more efficient initiation of surface-bound CTA by light. Surface-initiated polymerization via PET-RAFT with an initiator system of EosinY (EoY) and ascorbic acid (AscA) facilitates copolymer synthesis from HEA and 5-25 mol% SPA. The resulting polymer film with a thickness of a few nanometers was detected by atomic force microscopy (AFM) and ellipsometry. Water contact angle (CA) measurements demonstrate photo-switchable surface polarity, which is attributed to the photoisomerization between non-polar spiropyran and zwitterionic merocyanine isomer. Furthermore, the obtained spiropyran brushes show potential for further studies on light-programmable properties. In this context, it would be interesting to investigate whether swollen spiropyran-containing polymers change their configuration and thus their film thickness under the influence of light. In addition, further experiments using an AFM or microtribometer should evaluate whether light-programmable solvation enables a change in frictional properties between polymer brush surfaces.
The echo chamber model describes the development of groups in heterogeneous social networks. By heterogeneous social network we mean a set of individuals, each of whom represents exactly one opinion. The existing relationships between individuals can then be represented by a graph. The echo chamber model is a time-discrete model which, like a board game, is played in rounds. In each round, an existing relationship is randomly and uniformly selected from the network and the two connected individuals interact. If the opinions of the individuals involved are sufficiently similar, they continue to move closer together in their opinions, whereas in the case of opinions that are too far apart, they break off their relationship and one of the individuals seeks a new relationship. In this paper we examine the building blocks of this model. We start from the observation that changes in the structure of relationships in the network can be described by a system of interacting particles in a more abstract space.
These reflections lead to the definition of a new abstract graph that encompasses all possible relational configurations of the social network. This provides us with the geometric understanding necessary to analyse the dynamic components of the echo chamber model in Part III. As a first step, in Part 7, we leave aside the opinions of the inidividuals and assume that the position of the edges changes with each move as described above, in order to obtain a basic understanding of the underlying dynamics. Using Markov chain theory, we find upper bounds on the speed of convergence of an associated Markov chain to its unique stationary distribution and show that there are mutually identifiable networks that are not apparent in the dynamics under analysis, in the sense that the stationary distribution of the associated Markov chain gives equal weight to these networks.
In the reversible cases, we focus in particular on the explicit form of the stationary distribution as well as on the lower bounds of the Cheeger constant to describe the convergence speed.
The final result of Section 8, based on absorbing Markov chains, shows that in a reduced version of the echo chamber model, a hierarchical structure of the number of conflicting relations can be identified.
We can use this structure to determine an upper bound on the expected absorption time, using a quasi-stationary distribution. This hierarchy of structure also provides a bridge to classical theories of pure death processes. We conclude by showing how future research can exploit this link and by discussing the importance of the results as building blocks for a full theoretical understanding of the echo chamber model. Finally, Part IV presents a published paper on the birth-death process with partial catastrophe. The paper is based on the explicit calculation of the first moment of a catastrophe. This first part is entirely based on an analytical approach to second degree recurrences with linear coefficients. The convergence to 0 of the resulting sequence as well as the speed of convergence are proved. On the other hand, the determination of the upper bounds of the expected value of the population size as well as its variance and the difference between the determined upper bound and the actual value of the expected value. For these results we use almost exclusively the theory of ordinary nonlinear differential equations.
Plate tectonics describes the movement of rigid plates at the surface of the Earth as well as their complex deformation at three types of plate boundaries: 1) divergent boundaries such as rift zones and mid-ocean ridges, 2) strike-slip boundaries where plates grind past each other, such as the San Andreas Fault, and 3) convergent boundaries that form large mountain ranges like the Andes. The generally narrow deformation zones that bound the plates exhibit complex strain patterns that evolve through time. During this evolution, plate boundary deformation is driven by tectonic forces arising from Earth’s deep interior and from within the lithosphere, but also by surface processes, which erode topographic highs and deposit the resulting sediment into regions of low elevation. Through the combination of these factors, the surface of the Earth evolves in a highly dynamic way with several feedback mechanisms. At divergent boundaries, for example, tensional stresses thin the lithosphere, forcing uplift and subsequent erosion of rift flanks, which creates a sediment source. Meanwhile, the rift center subsides and becomes a topographic low where sediments accumulate. This mass transfer from foot- to hanging wall plays an important role during rifting, as it prolongs the activity of individual normal faults. When rifting continues, continents are eventually split apart, exhuming Earth’s mantle and creating new oceanic crust. Because of the complex interplay between deep tectonic forces that shape plate boundaries and mass redistribution at the Earth’s surface, it is vital to understand feedbacks between the two domains and how they shape our planet.
In this study I aim to provide insight on two primary questions: 1) How do divergent and strike-slip plate boundaries evolve? 2) How is this evolution, on a large temporal scale and a smaller structural scale, affected by the alteration of the surface through erosion and deposition? This is done in three chapters that examine the evolution of divergent and strike-slip plate boundaries using numerical models. Chapter 2 takes a detailed look at the evolution of rift systems using two-dimensional models. Specifically, I extract faults from a range of rift models and correlate them through time to examine how fault networks evolve in space and time. By implementing a two-way coupling between the geodynamic code ASPECT and landscape evolution code FastScape, I investigate how the fault network and rift evolution are influenced by the system’s erosional efficiency, which represents many factors like lithology or climate. In Chapter 3, I examine rift evolution from a three-dimensional perspective. In this chapter I study linkage modes for offset rifts to determine when fast-rotating plate-boundary structures known as continental microplates form. Chapter 4 uses the two-way numerical coupling between tectonics and landscape evolution to investigate how a strike-slip boundary responds to large sediment loads, and whether this is sufficient to form an entirely new type of flexural strike-slip basin.
We investigate the effect of the COVID-19 pandemic on self-employed people’s mental health. Using representative longitudinal survey data from Germany, we reveal differential effects by gender: whereas self-employed women experienced a substantial deterioration in their mental health, self-employed men displayed no significant changes up to early 2021. Financial losses are important in explaining these differences. In addition, we find larger mental health responses among self-employed women who were directly affected by government-imposed restrictions and bore an increased childcare burden due to school and daycare closures. We also find that self-employed individuals who are more resilient coped better with the crisis.
In light of climate change mitigation efforts, revenues from climate policies are growing, with no consensus yet on how they should be used. Potential efficiency gains from reducing distortionary taxes and the distributional implications of different revenue recycling schemes are currently debated. To account for households heterogeneity and dynamic trade-offs, we study the macroeconomic and welfare performance of different revenue recycling schemes using an Environmental Two-Agent New-Keynesian model, calibrated on the German economy. We find that, in the long run, welfare gains are higher when revenues are used to reduce distortionary taxes on capital, but this comes at the cost of higher inequality: while all households prefer labor income tax reductions to lump-sum transfers, only financially unconstrained households are better off when reducing taxes on capital income. Interestingly, we find that over the transition period relevant to meet short-medium run climate targets, labor income tax cuts are the most efficient and equitable instrument.
Salt deposits offer a variety of usage types. These include the mining of rock salt and potash salt as important raw materials, the storage of energy in man-made underground caverns, and the disposal of hazardous substances in former mines. The most serious risk with any of these usage types comes from the contact with groundwater or surface water. It causes an uncontrolled dissolution of salt rock, which in the worst case can result in the flooding or collapse of underground facilities. Especially along potash seams, cavernous structures can spread quickly, because potash salts show a much higher solubility than rock salt. However, as their chemical behavior is quite complex, previous models do not account for these highly soluble interlayers. Therefore, the objective of the present thesis is to describe the evolution of cavernous structures along potash seams in space and time in order to improve hazard mitigation during the utilization of salt deposits.
The formation of cavernous structures represents an interplay of chemical and hydraulic processes. Hence, the first step is to systematically investigate the dissolution and precipitation reactions that occur when water and potash salt come into contact. For this purpose, a geochemical reaction model is used. The results show that the minerals are only partially dissolved, resulting in a porous sponge like structure. With the saturation of the solution increasing, various secondary minerals are formed, whose number and type depend on the original rock composition. Field data confirm a correlation between the degree of saturation and the distance from the center of the cavern, where solution is entering. Subsequently, the reaction model is coupled with a flow and transport code and supplemented by a novel approach called ‘interchange’. The latter enables the exchange of solution and rock between areas of different porosity and mineralogy, and thus ultimately the growth of the cavernous structure. By means of several scenario analyses, cavern shape, growth rate and mineralogy are systematically investigated, taking also heterogeneous potash seams into account. The results show that basically four different cases can be distinguished, with mixed forms being a frequent occurrence in nature. The classification scheme is based on the dimensionless numbers Péclet and Damköhler, and allows for a first assessment of the hazard potential. In future, the model can be applied to any field case, using measurement data for calibration.
The presented research work provides a reactive transport model that is able to spatially and temporally characterize the propagation of cavernous structures along potash seams for the first time. Furthermore, it allows to determine thickness and composition of transition zones between cavern center and unaffected salt rock. The latter is particularly important in potash mining, so that natural cavernous structures can be located at an early stage and the risk of mine flooding can thus be reduced. The models may also contribute to an improved hazard prevention in the construction of storage caverns and the disposal of hazardous waste in salt deposits. Predictions regarding the characteristics and evolution of cavernous structures enable a better assessment of potential hazards, such as integrity or stability loss, as well as of suitable mitigation measures.
»Plus outre« – immer weiter
(2022)
Major challenges during geothermal exploration and exploitation include the structural-geological characterization of the geothermal system and the application of sustainable monitoring concepts to explain changes in a geothermal reservoir during production and/or reinjection of fluids. In the absence of sufficiently permeable reservoir rocks, faults and fracture networks are preferred drilling targets because they can facilitate the migration of hot and/or cold fluids. In volcanic-geothermal systems considerable amounts of gas emissions can be released at the earth surface, often related to these fluid-releasing structures.
In this thesis, I developed and evaluated different methodological approaches and measurement concepts to determine the spatial and temporal variation of several soil gas parameters to understand the structural control on fluid flow. In order to validate their potential as innovative geothermal exploration and monitoring tools, these methodological approaches were applied to three different volcanic-geothermal systems. At each site an individual survey design was developed regarding the site-specific questions.
The first study presents results of the combined measurement of CO2 flux, ground temperatures, and the analysis of isotope ratios (δ13CCO2, 3He/4He) across the main production area of the Los Humeros geothermal field, to identify locations with a connection to its supercritical (T > 374◦C and P > 221 bar) geothermal reservoir. The results of the systematic and large-scale (25 x 200 m) CO2 flux scouting survey proved to be a fast and flexible way to identify areas of anomalous degassing. Subsequent sampling with high resolution surveys revealed the actual extent and heterogenous pattern of anomalous degassing areas. They have been related to the internal fault hydraulic architecture and allowed to assess favourable structural settings for fluid flow such as fault intersections. Finally, areas of unknown structurally controlled permeability with a connection to the superhot geothermal reservoir have been determined, which represent promising targets for future geothermal exploration and development.
In the second study, I introduce a novel monitoring approach by examining the variation of CO2 flux to monitor changes in the reservoir induced by fluid reinjection. For that reason, an automated, multi-chamber CO2 flux system was deployed across the damage zone of a major normal fault crossing the Los Humeros geothermal field. Based on the results of the CO2 flux scouting survey, a suitable site was selected that had a connection to the geothermal reservoir, as identified by hydrothermal CO2 degassing and hot ground temperatures (> 50 °C). The results revealed a response of gas emissions to changes in reinjection rates within 24 h, proving an active hydraulic communication between the geothermal reservoir and the earth surface. This is a promising monitoring strategy that provides nearly real-time and in-situ data about changes in the reservoir and allows to timely react to unwanted changes (e.g., pressure decline, seismicity).
The third study presents results from the Aluto geothermal field in Ethiopia where an area-wide and multi-parameter analysis, consisting of measurements of CO2 flux, 222Rn, and 220Rn activity concentrations and ground temperatures was conducted to detect hidden permeable structures. 222Rn and 220Rn activity concentrations are evaluated as a complementary soil gas parameter to CO2 flux, to investigate their potential to understand tectono-volcanic degassing. The combined measurement of all parameters enabled to develop soil gas fingerprints, a novel visualization approach. Depending on the magnitude of gas emissions and their migration velocities the study area was divided in volcanic (heat), tectonic (structures), and volcano-tectonic dominated areas. Based on these concepts, volcano-tectonic dominated areas, where hot hydrothermal fluids migrate along permeable faults, present the most promising targets for future geothermal exploration and development in this geothermal field. Two of these areas have been identified in the south and south-east which have not yet been targeted for geothermal exploitation. Furthermore, two unknown areas of structural related permeability could be identified by 222Rn and 220Rn activity concentrations.
Eventually, the fourth study presents a novel measurement approach to detect structural controlled CO2 degassing, in Ngapouri geothermal area, New Zealand. For the first time, the tunable diode laser (TDL) method was applied in a low-degassing geothermal area, to evaluate its potential as a geothermal exploration method. Although the sampling approach is based on profile measurements, which leads to low spatial resolution, the results showed a link between known/inferred faults and increased CO2 concentrations. Thus, the TDL method proved to be a successful in the determination of structural related permeability, also in areas where no obvious geothermal activity is present. Once an area of anomalous CO2 concentrations has been identified, it can be easily complemented by CO2 flux grid measurements to determine the extent and orientation of the degassing segment.
With the results of this work, I was able to demonstrate the applicability of systematic and area-wide soil gas measurements for geothermal exploration and monitoring purposes. In particular, the combination of different soil gases using different measurement networks enables the identification and characterization of fluid-bearing structures and has not yet been used and/or tested as standard practice. The different studies present efficient and cost-effective workflows and demonstrate a hands-on approach to a successful and sustainable exploration and monitoring of geothermal resources. This minimizes the resource risk during geothermal project development. Finally, to advance the understanding of the complex structure and dynamics of geothermal systems, a combination of comprehensive and cutting-edge geological, geochemical, and geophysical exploration methods is essential.
To achieve a sustainable energy economy, it is necessary to turn back on the combustion of fossil fuels as a means of energy production and switch to renewable sources. However, their temporal availability does not match societal consumption needs, meaning that renewably generated energy must be stored in its main generation times and allocated during peak consumption periods. Electrochemical energy storage (EES) in general is well suited due to its infrastructural independence and scalability. The lithium ion battery (LIB) takes a special place, among EES systems due to its energy density and efficiency, but the scarcity and uneven geological occurrence of minerals and ores vital for many cell components, and hence the high and fluctuating costs will decelerate its further distribution.
The sodium ion battery (SIB) is a promising successor to LIB technology, as the fundamental setup and cell chemistry is similar in the two systems. Yet, the most widespread negative electrode material in LIBs, graphite, cannot be used in SIBs, as it cannot store sufficient amounts of sodium at reasonable potentials. Hence, another carbon allotrope, non-graphitizing or hard carbon (HC) is used in SIBs. This material consists of turbostratically disordered, curved graphene layers, forming regions of graphitic stacking and zones of deviating layers, so-called internal or closed pores.
The structural features of HC have a substantial impact of the charge-potential curve exhibited by the carbon when it is used as the negative electrode in an SIB. At defects and edges an adsorption-like mechanism of sodium storage is prevalent, causing a sloping voltage curve, ill-suited for the practical application in SIBs, whereas a constant voltage plateau of relatively high capacities is found immediately after the sloping region, which recent research attributed to the deposition of quasimetallic sodium into the closed pores of HC.
Literature on the general mechanism of sodium storage in HCs and especially the role of the closed pore is abundant, but the influence of the pore geometry and chemical nature of the HC on the low-potential sodium deposition is yet in an early stage. Therefore, the scope of this thesis is to investigate these relationships using suitable synthetic and characterization methods. Materials of precisely known morphology, porosity, and chemical structure are prepared in clear distinction to commonly obtained ones and their impact on the sodium storage characteristics is observed. Electrochemical impedance spectroscopy in combination with distribution of relaxation times analysis is further established as a technique to study the sodium storage process, in addition to classical direct current techniques, and an equivalent circuit model is proposed to qualitatively describe the HC sodiation mechanism, based on the recorded data. The obtained knowledge is used to develop a method for the preparation of closed porous and non-porous materials from open porous ones, proving not only the necessity of closed pores for efficient sodium storage, but also providing a method for effective pore closure and hence the increase of the sodium storage capacity and efficiency of carbon materials.
The insights obtained and methods developed within this work hence not only contribute to the better understanding of the sodium storage mechanism in carbon materials of SIBs, but can also serve as guidance for the design of efficient electrode materials.
The key to reduce the energy required for specific transformations in a selective manner is the employment of a catalyst, a very small molecular platform that decides which type of energy to use. The field of photocatalysis exploits light energy to shape one type of molecules into others, more valuable and useful.
However, many challenges arise in this field, for example, catalysts employed usually are based on metal derivatives, which abundance is limited, they cannot be recycled and are expensive. Therefore, carbon nitrides materials are used in this work to expand horizons in the field of photocatalysis.
Carbon nitrides are organic materials, which can act as recyclable, cheap, non-toxic, heterogeneous photocatalysts. In this thesis, they have been exploited for the development of new catalytic methods, and shaped to develop new types of processes.
Indeed, they enabled the creation of a new photocatalytic synthetic strategy, the dichloromethylation of enones by dichloromethyl radical generated in situ from chloroform, a novel route for the making of building blocks to be used for the productions of active pharmaceutical compounds.
Then, the ductility of these materials allowed to shape carbon nitride into coating for lab vials, EPR capillaries, and a cell of a flow reactor showing the great potential of such flexible technology in photocatalysis.
Afterwards, their ability to store charges has been exploited in the reduction of organic substrates under dark conditions, gaining new insights regarding multisite proton coupled electron transfer processes.
Furthermore, the combination of carbon nitrides with flavins allowed the development of composite materials with improved photocatalytic activity in the CO2 photoreduction.
Concluding, carbon nitrides are a versatile class of photoactive materials, which may help to unveil further scientific discoveries and to develop a more sustainable future.
Development of chronic pain after a low back pain episode is associated with increased pain sensitivity, altered pain processing mechanisms and the influence of psychosocial factors. Although there is some evidence that multimodal therapy (such as behavioral or motor control therapy) may be an important therapeutic strategy, its long-term effect on pain reduction and psychosocial load is still unclear. Prospective longitudinal designs providing information about the extent of such possible long-term effects are missing. This study aims to investigate the long-term effects of a homebased uni- and multidisciplinary motor control exercise program on low back pain intensity, disability and psychosocial variables. 14 months after completion of a multicenter study comparing uni- and multidisciplinary exercise interventions, a sample of one study center (n = 154) was assessed once more. Participants filled in questionnaires regarding their low back pain symptoms (characteristic pain intensity and related disability), stress and vital exhaustion (short version of the Maastricht Vital Exhaustion Questionnaire), anxiety and depression experiences (the Hospital and Anxiety Depression Scale), and pain-related cognitions (the Fear Avoidance Beliefs Questionnaire). Repeated measures mixed ANCOVAs were calculated to determine the long-term effects of the interventions on characteristic pain intensity and disability as well as on the psychosocial variables. Fifty four percent of the sub-sample responded to the questionnaires (n = 84). Longitudinal analyses revealed a significant long-term effect of the exercise intervention on pain disability. The multidisciplinary group missed statistical significance yet showed a medium sized long-term effect. The groups did not differ in their changes of the psychosocial variables of interest. There was evidence of long-term effects of the interventions on pain-related disability, but there was no effect on the other variables of interest. This may be partially explained by participant's low comorbidities at baseline. Results are important regarding costless homebased alternatives for back pain patients and prevention tasks. Furthermore, this study closes the gap of missing long-term effect analysis in this field.
We provide the first estimates of the impact of managers’ risk preferences on their training allocation decisions. Our conceptual framework links managers’ risk preferences to firms’ training decisions through the bonuses they expect to receive. Risk-averse managers are expected to select workers with low turnover risk and invest in specific rather than general training. Empirical evidence supporting these predictions is provided using a novel vignette study embedded in a nationally representative survey of firm managers. Risk-tolerant and risk-averse decision makers have significantly different training preferences. Risk aversion results in increased sensitivity to turnover risk. Managers who are risk-averse offer significantly less general training and, in some cases, are more reluctant to train workers with a history of job mobility. All managers, irrespective of their risk preferences, are sensitive to the investment risk associated with training, avoiding training that is more costly or targets those with less occupational expertise or nearing retirement. This suggests the risks of training are primarily due to the risk that trained workers will leave the firm (turnover risk) rather than the risk that the benefits of training do not outweigh the costs (investment risk).
Carbon dioxide removal (CDR) moves atmospheric carbon to geological or land-based sinks. In a first-best setting, the optimal use of CDR is achieved by a removal subsidy that equals the optimal carbon tax and marginal damages. We derive second-best subsidies for CDR when no global carbon price exists but a national government implements a unilateral climate policy. We find that the optimal carbon tax differs from an optimal CDR subsidy because of carbon leakage, terms-of-trade and fossil resource rent dynamics. First, the optimal removal subsidy tends to be larger than the carbon tax because of lower supply-side leakage on fossil resource markets. Second, terms-of-trade effects exacerbate this wedge for net resource exporters, implying even larger removal subsidies. Third, the optimal removal subsidy may fall below the carbon tax for resource-poor countries when marginal environmental damages are small.
American occupying forces made the promotion of Jewish-Christian dialogue part of their plans for postwar German reconstruction. They sought to export American models of Jewish-Christian cooperation to Germany, while simultaneously validating and valorizing claims about the connection between democracy and tri-faith religious pluralism in the United States. The small size of the Jewish population in Germany meant that Jews did not set the terms of these discussions, and evidence shows that both German and American Jews expressed skepticism about participating in dialogue in the years immediately following the Holocaust. But opting out would have meant that discussions in Germany about the Judeo-Christian tradition that the American government advanced as the centerpiece of postwar democratic reconstruction would take place without a Jewish contribution. American Jewish leaders, present in Germany and in the US, therefore decided to opt in, not because they supported the project, but because it seemed far riskier to be left out.
Acquiring Syntactic Variability: The Production of Wh-Questions in Children and Adults Speaking Akan
(2020)
This paper investigates the predictions of the Derivational Complexity Hypothesis by studying the acquisition of wh-questions in 4- and 5-year-old Akan-speaking children in an experimental approach using an elicited production and an elicited imitation task. Akan has two types of wh-question structures (wh-in-situ and wh-ex-situ questions), which allows an investigation of children’s acquisition of these two question structures and their preferences for one or the other. Our results show that adults prefer to use wh-ex-situ questions over wh-in-situ questions. The results from the children show that both age groups have the two question structures in their linguistic repertoire. However, they differ in their preferences in usage in the elicited production task: while the 5-year-olds preferred the wh-in-situ structure over the wh-ex-situ structure, the 4-year-olds showed a selective preference for the wh-in-situ structure in who-questions. These findings suggest a developmental change in wh-question preferences in Akan-learning children between 4 and 5 years of age with a so far unobserved u-shaped developmental pattern. In the elicited imitation task, all groups showed a strong tendency to maintain the structure of in-situ and ex-situ questions in repeating grammatical questions. When repairing ungrammatical ex-situ questions, structural changes to grammatical in-situ questions were hardly observed but the insertion of missing morphemes while keeping the ex-situ structure. Together, our findings provide only partial support for the Derivational Complexity Hypothesis.
Transitional Justice
(2022)
This publication deals with the topic of transitional justice. In six case studies, the authors link theoretical and practical implications in order to develop some innovative approaches. Their proposals might help to deal more effectively with the transition of societies, legal orders and political systems.
Young academics from various backgrounds provide fresh insights and demonstrate the relevance of the topic. The chapters analyse transitions and conflicts in Sierra Leone, Argentina, Nicaragua, Nepal, and South Sudan as well as Germany’s colonial genocide in Namibia. Thus, the book provides the reader with new insights and contributes to the ongoing debate about transitional justice.
Organisms often employ ecophysiological strategies to exploit environmental conditions and ensure bio-energetic success. However, the many complexities involved in the differential expression and flexibility of these strategies are rarely fully understood. Therefore, for the first time, using a three-part cross-disciplinary laboratory experimental analysis, we investigated the diversity and plasticity of photoresponsive traits employed by one family of environmentally contrasting, ecologically important phytoflagellates. The results demonstrated an extensive inter-species phenotypic diversity of behavioural, physiological, and compositional photoresponse across the Chlamydomonadaceae, and a multifaceted intra-species phenotypic plasticity, involving a broad range of beneficial photoacclimation strategies, often attributable to environmental predisposition and phylogenetic differentiation. Deceptively diverse and sophisticated strong (population and individual cell) behavioural photoresponses were observed, with divergence from a general preference for low light (and flexibility) dictated by intra-familial differences in typical habitat (salinity and trophy) and phylogeny. Notably, contrasting lower, narrow, and flexible compared with higher, broad, and stable preferences were observed in freshwater vs. brackish and marine species. Complex diversity and plasticity in physiological and compositional photoresponses were also discovered. Metabolic characteristics (such as growth rates, respiratory costs and photosynthetic capacity, efficiency, compensation and saturation points) varied elaborately with species, typical habitat (often varying more in eutrophic species, such as Chlamydomonas reinhardtii), and culture irradiance (adjusting to optimise energy acquisition and suggesting some propensity for low light). Considerable variations in intracellular pigment and biochemical composition were also recorded. Photosynthetic and accessory pigments (such as chlorophyll a, xanthophyll-cycle components, chlorophyll a:b and chlorophyll a:carotenoid ratios, fatty acid content and saturation ratios) varied with phylogeny and typical habitat (to attune photosystem ratios in different trophic conditions and to optimise shade adaptation, photoprotection, and thylakoid architecture, particularly in freshwater environments), and changed with irradiance (as reaction and harvesting centres adjusted to modulate absorption and quantum yield). The complex, concomitant nature of the results also advocated an integrative approach in future investigations. Overall, these nuanced, diverse, and flexible photoresponsive traits will greatly contribute to the functional ecology of these organisms, addressing environmental heterogeneity and potentially shaping individual fitness, spatial and temporal distribution, prevalence, and ecosystem dynamics.
Subsidizing the geographical mobility of unemployed workers may improve welfare by relaxing their financial constraints and allowing them to find jobs in more prosperous regions. We exploit regional variation in the promotion of mobility programs along administrative borders of German employment agency districts to investigate the causal effect of offering such financial incentives on the job search behavior and labor market integration of unemployed workers. We show that promoting mobility – as intended – causes job seekers to increase their search radius, apply for and accept distant jobs. At the same time, local job search is reduced with adverse consequences for reemployment and earnings. These unintended negative effects are provoked by spatial search frictions. Overall, the unconditional provision of mobility programs harms the welfare of unemployed job seekers.
A Secular Tradition
(2021)
This article focuses on the social philosopher Horace Kallen and the revisions he made to the concept of cultural pluralism that he first developed in the early 20th century, applying it to postwar America and the young State of Israel. It shows how he opposed the assumption that the United States’ social order was based on a “Judeo-Christian tradition.” By constructing pluralism as a civil religion and carving out space for secular self-understandings in midcentury America, Kallen attempted to preserve the integrity of his earlier political visions, developed during World War I, of pluralist societies in the United States and Palestine within an internationalist global order. While his perspective on the State of Israel was largely shaped by his American experiences, he revised his approach to politically functionalizing religious traditions as he tested his American understanding of a secular, pluralist society against the political theology effective in the State of Israel. The trajectory of Kallen’s thought points to fundamental questions about the compatibility of American and Israeli understandings of religion’s function in society and its relation to political belonging, especially in light of their transnational connection through American Jewish support for the recently established state.
In Search of Belonging
(2021)
More than 200,000 Jews left the Habsburg province of Galicia between 1881 and 1910. No longer living in the places of their childhood, they settled in urban centers, such as in New York’s Lower East Side. In this neighborhood, Galician Jews began to search for new relationships that linked the places they left and the ones where they arrived and settled. By looking at Galicia through the lens of autobiographical writings by former Jewish immigrants who became established residents of New York, this article emphasizes the role of regionalism in the context of transnational conceptions of a new American Jewish self-understanding. It argues that the key to analyzing the evolution of “eastern Europe” as a common place of origin for American Jewry is the constant dialogue between the places of origin and arrival. Specifically, philanthropic efforts during and after the First World War and the proliferation of tourism both enabled these settled immigrants to gradually replace regional notions, such as the idea of Galicia, with a mythical image of eastern Europe to create a sense of community as American Jews.
When the Jewish Theological Seminary in Breslau opened its doors in 1854, it established a novel form of rabbinical education: the systematic combination of Jewish studies at the seminary in parallel with university studies. The Breslau seminary became the model for most later institutions for rabbinical training in Europe and the United States. The seminaries were the new sites of modern Jewish scholarship, especially the academic study of Judaism (Wissenschaft des Judentums). Their function and goal were to preserve, (re)organize, and transmit Jewish knowledge in the modern age. As such, they became central nodes in Jewish scholarly networks. This case study highlights the multi-nodal connections between the Conservative seminaries in Breslau, Philadelphia, New York, Budapest, and Vienna. At the same time, it is intended to provide an example of the potential of transnational and transfer studies for the history of the Jewish religious learning in Europe and the United States.
As mid-19th-century American Jews introduced radical changes to their religious observance and began to define Judaism in new ways, to what extent did they engage with European Jewish ideas? Historians often approach religious change among Jews from German lands during this period as if Jewish immigrants had come to America with one set of ideas that then evolved solely in conversation with their American contexts. Historians have similarly cast the kinds of Judaism Americans created as both unique to America and uniquely American. These characterizations are accurate to an extent. But to what extent did Jewish innovations in the United States take place in conversation with European Jewish developments? Looking to the 19th-century American Jewish press, this paper seeks to understand how American Jews engaged European Judaism in formulating their own ideas, understanding themselves, and understanding their place in world Judaism.
This article explores the multi-directional geographic trajectories and ties of Jews who came to the United States in the 19th century, working to complicate simplistic understandings of “German” Jewish immigration. It focuses on the case study of Henry Cohn, an ordinary Russian-born Jew whose journeys took him to Prussia, New York, Savannah, and California. Once in the United States he returned to Europe twice, the second time permanently, although a grandson ended up in California, where he worked to ensure the preservation of Cohn’s records. This story highlights how Jews navigated and transgressed national boundaries in the 19th century and the limitations of the historical narratives that have been constructed from their experiences.
The COVID-19 pandemic created the largest experiment in working from home. We study how persistent telework may change energy and transport consumption and costs in Germany to assess the distributional and environmental implications when working from home will stick. Based on data from the German Microcensus and available classifications of working-from-home feasibility for different occupations, we calculate the change in energy consumption and travel to work when 15% of employees work full time from home. Our findings suggest that telework translates into an annual increase in heating energy expenditure of 110 euros per worker and a decrease in transport expenditure of 840 euros per worker. All income groups would gain from telework but high-income workers gain twice as much as low-income workers. The value of time saving is between 1.3 and 6 times greater than the savings from reduced travel costs and almost 9 times higher for high-income workers than low-income workers. The direct effects on CO₂ emissions due to reduced car commuting amount to 4.5 millions tons of CO₂, representing around 3 percent of carbon emissions in the transport sector.
Schire Simroh
(2021)
Arno Nadel ist 1878 in Wilna geboren und 1943 in Auschwitz ermordet worden. Es sind nur einige wenige Dokumente überliefert, anhand derer sich der Lebensweg von Arno Nadel rekonstruieren lässt. Das ist nur wenig verwunderlich, denn die Welt von Arno Nadel ist drei Mal untergegangen: zuerst die jüdische Welt von Wilna, dann die deutsche von Königsberg und schließlich die deutsch-jüdische von Berlin. Es ist allerdings erstaunlich, wie gründlich Arno Nadels Wirken danach in Vergessenheit geriet. Allein seine Vielseitigkeit hätte eigentlich diesen außergewöhnlichen Menschen vor dem Vergessen bewahren müssen. Arno Nadel war Dichter, Philosoph, Bühnenautor, Religionsgelehrter, Übersetzer, Maler und Grafiker, Komponist, Musik- und Literaturwissenschaftler, Ethnologe, Chordirigent, Pianist, Organist und Musikpublizist. Wenn man von Beschäftigungen zum reinen Broterwerb absieht, wie seiner Anstellung als Lehrer an einer Schule. All diese vielseitigen Tätigkeiten waren keineswegs dilettantische Versuche eines zerstreuten Menschen, sondern vollwertige Berufe und Berufungen, die er mehr oder weniger gleichzeitig mit höchster Intensität und Professionalität ausübte. In dieser Hinsicht war Nadel eine nicht nur zu seiner Zeit einzigartige Erscheinung, ein Phänomen, das eher an die Künstlerpersönlichkeiten der Renaissance erinnert. Auf jedem seiner Schaffensgebiete war Nadel unwahrscheinlich produktiv, so produktiv, dass man sich mit Ehrfurcht fragen muss, wie ein Mensch im Laufe seines Lebens derart viele geistige Werte zu schaffen vermochte. Obwohl ein großer Teil seines Nachlasses den Zweiten Weltkrieg nicht überdauerte, ist die Fülle der erhaltenen Manuskripte und publizierten Werke kaum zu überblicken. Um sein gesamtes Werk umfassend auszuwerten, bedürfte es der Anstrengungen eines ganzen Teams von Wissenschaftlern aus unterschiedlichen Disziplinen.
Für diese CD-Produktion wurden u.a. fünf Kompositionen für Chasan, Chor und Orgel für den Freitagabend-Gottesdienst eingespielt, die ursprünglich in dem Sammelband „Schire Simroh” erschienen sind, der synagogale Kompositionen zeitgenössischer Autoren zusammentrug. Sie sind für den Wettbewerb des Allgemeinen Deutschen Kantoren-Verbandes e. V. im Jahre 1926 geschrieben worden und im Verlag J. Kauffmann in Frankfurt am Main publiziert worden. 1930 wurde ein weiterer Sonderdruck veröffentlicht. Diese äußerst seltene Ausgabe wurde 1968 im Journal of Synagogue Music reproduziert. Dazu zählt auch das Stück “W’schomru”, das – ebenso wie die anderen vier publizierten Stücke – zum Kompendium gehörte. Diese Komposition gibt einen Eindruck von Nadels expressivem Stil, der “die östliche Freiheit des Ausdrucks mit dem westlichen Instrumentarium, einen weitgehend traditionellen jüdischen Melodieaufbau mit europäischer Polyphonie und harmonischer Kühnheit verbindet”. (Vgl. Jascha Nemtsov: Arno Nadel. Sein Beitrag zur jüdischen Musikkultur. Berlin 2008.)
Zusätzlich befindet sich das Stück “J’hi Scholom” auf der CD, ein Stück für Chasan, Chor und Orgel, das Arno Nadel zur Einweihung des Friedenstempels in Berlin komponiert hat.
Der Psalm 24, herausgegeben zum 70. Geburtstag von Moritz Schaefer, am 21. Mai 1927 mit der Widmung “Herrn Prof. Moritz Schaefer, dem Freunde aller großen jüdischen Bestrebungen” ist eine A-Capella-Komposition für Männerchor mit Kantor-Solo, die für die Liturgie der Torahlesung geschrieben wurde.
Drei Solo-Orgelvorspiele umrahmen diese Aufnahme. Das erste ist für die Hohen Feiertage komponiert und wurde nach den repräsentativsten liturgischen Motiven von “Bar’chu” und “Hamelech” für das Abend- und Morgengebet komponiert.
Das mittlere Orgelvorspiel hat Arno Nadel für die drei Wochen vor dem Tisch’a B’Av geschrieben, die traurigsten Wochen des jüdischen Volkes, in deren Verlauf an die Zerstörung beider Tempel in Jerusalem erinnert wird. Dieses Vorspiel basiert auf den Motiven der Liturgie für die Tage, an denen zum einen die “Kinnot” rezitiert werden, liturgische Gedichte, die die Leiden des Volkes Israels im Exil beschreiben, und zum anderen die Klagelieder von Jeremia, die die Trauer und den Schrecken der Zerstörung des Tempels beschreiben. Das abschließende Stück dieser CD eröffnet den letzten Teil des Gottesdienstes am Jom Kippur, dem Versöhnungstag. Es trägt den Namen „Ne’ilah“ und entspricht dem Gebet, das vor dem Schließen der Tempeltore in Jerusalem am Ende des Tages gesprochen wurde.
In Germany, the productivity of professional services, a sector dominated by micro and small firms, declined by 40 percent between 1995 and 2014. This productivity decline also holds true for professional services in other European countries. Using a German firm-level dataset of 700,000 observations between 2003 and 2017, we analyze this largely uncovered phenomenon among professional services, the 4th largest sector in the EU15 business economy, which provide important intermediate services for the rest of the economy. We show that changes in the value chain explain about half of the decline and the increase in part-time employment is a further minor part of the decline. In contrast to expectations, the entry of micro and small firms, despite their lower productivity levels, is not responsible for the decline. We also cannot confirm the conjecture that weakening competition allows unproductive firms to remain in the market.
Starting in 2009, the German state of Saxony distributed sports club membership vouchers among all 33,000 third graders in the state. The policy’s objective was to encourage them to develop a long-term habit of exercising. In 2018, we carried out a large register-based survey among several cohorts in Saxony and two neighboring states. Our difference-in-differences estimations show that, even after a decade, awareness of the voucher program was significantly higher in the treatment group. We also find that youth received and redeemed the vouchers. However, we do not find significant short- or long-term effects on sports club membership, physical activity, overweightness, or motor skills.
Im Projekt „Forschungsdatenmanagement in Brandenburg (FDM-BB)“ wurden grundlegende Erkenntnisse bezüglich der Anforderungen und des Status Quo im Bereich Forschungsdatenmanagement (FDM) an den acht brandenburgischen Hochschulen generiert mit dem Ziel, daraus konkrete Handlungs- und Implementierungsempfehlungen für Brandenburg abzuleiten.
Mit Hilfe von spezifischen Umfragen (FactSheets, FDM-Palette) an den Hochschulen und Interviews mit den anderen geförderten FDM-Bundeslandinitiativen konnte eine Priorisierung der nächsten Schritte auf dem Weg hin zu einem institutionellen und nachhaltigen Forschungsdatenmanagement identifiziert werden, die jeweils in den Verantwortungsbereichen der folgenden drei Akteursgruppen liegen: Ministerium für Wirtschaft, Forschung und Kultur in Brandenburg (MWFK), die einzelne Hochschule und für gemeinsame Maßnahmen die kooperative Umsetzung durch (fast) alle Hochschulen.
Zusätzlich wurden Implementierungsempfehlungen erarbeitet, wie der lokale Kompetenzaufbau an den einzelnen Hochschulen in Brandenburg, die kooperative Bereitstellung landesweit relevanter IT-Dienste und Dienstleistungen sowie die Koordinierung FDM-BB.
Ziel ist auch, für Brandenburg gemeinsam eine Forschungsdatenstrategie zu formulieren, die alle brandenburgischen Einrichtungen einbezieht und mit Hilfe von kooperativ verteilten Verantwortlichkeiten dem (noch) sehr dynamischen Thema Forschungsdatenmanagement gerecht werden kann.
Digitale Diagnostik
(2021)
Against a background of increasing violence against non-natives, we estimate the effect of hate crime on refugees’ mental health in Germany. For this purpose, we combine two datasets: administrative records on xenophobic crime against refugee shelters by the Federal Criminal Office and the IAB-BAMF-SOEP Survey of Refugees. We apply a regression discontinuity in time design to estimate the effect of interest. Our results indicate that hate crime has a substantial negative effect on several mental health indicators, including the Mental Component Summary score and the Patient Health Questionnaire-4 score. The effects are stronger for refugees with closer geographic proximity to the focal hate crime and refugees with low country-specific human capital. While the estimated effect is only transitory, we argue that negative mental health shocks during the critical period after arrival have important long-term consequences. Keywords: Mental health, hate crime, migration, refugees, human capital.
While a growing body of literature finds positive impacts of Start-Up Subsidies (SUS) on labor market outcomes of participants, little is known about how the design of these programs shapes their effectiveness and hence how to improve policy. As experimental variation in program design is unavailable, we exploit the 2011 reform of the current German SUS program for the unemployed which strengthened case-workers’ discretionary power, increased entry requirements and reduced monetary support. We estimate the impact of the reform on the program’s effectiveness using samples of participants and non-participants from before and after the reform. To control for time-constant unobserved heterogeneity as well as differential selection patterns based on observable characteristics over time, we combine Difference-in-Differences with inverse probability weighting using covariate balancing propensity scores. Holding participants’ observed characteristics as well as macroeconomic conditions constant, the results suggest that the reform was successful in raising employment effects on average. As these findings may be contaminated by changes in selection patterns based on unobserved characteristics, we assess our results using simulation-based sensitivity analyses and find that our estimates are highly robust to changes in unobserved characteristics. Hence, the reform most likely had a positive impact on the effectiveness of the program, suggesting that increasing entry requirements and reducing support in-creased the program’s impacts while reducing the cost per participant.
The large literature that aims to find evidence of climate migration delivers mixed findings. This meta-regression analysis i) summarizes direct links between adverse climatic events and migration, ii) maps patterns of climate migration, and iii) explains the variation in outcomes. Using a set of limited dependent variable models, we meta-analyze thus-far the most comprehensive sample of 3,625 estimates from 116 original studies and produce novel insights on climate migration. We find that extremely high temperatures and drying conditions increase migration. We do not find a significant effect of sudden-onset events. Climate migration is most likely to emerge due to contemporaneous events, to originate in rural areas and to take place in middle-income countries, internally, to cities. The likelihood to become trapped in affected areas is higher for women and in low-income countries, particularly in Africa. We uniquely quantify how pitfalls typical for the broader empirical climate impact literature affect climate migration findings. We also find evidence of different publication biases.
We develop a model of optimal carbon taxation and redistribution taking into account horizontal equity concerns by considering heterogeneous energy efficiencies. By deriving first- and second-best rules for policy instruments including carbon taxes, transfers and energy subsidies, we then investigate analytically how horizontal equity is considered in the social welfare maximizing tax structure. We calibrate the model to German household data and a 30 percent emission reduction goal. Our results show that energy-intensive households should receive more redistributive resources than energy-efficient households if and only if social inequality aversion is sufficiently high. We further find that redistribution of carbon tax revenue via household-specific transfers is the first-best policy. Equal per-capita transfers do not suffer from informational problems, but increase mitigation costs by around 15 percent compared to the first- best for unity inequality aversion. Adding renewable energy subsidies or non-linear energy subsidies, reduces mitigation costs further without relying on observability of households’ energy efficiency.
We investigate how the economic consequences of the pandemic, and of the government-mandated measures to contain its spread, affect the self-employed – particularly women – in Germany. For our analysis, we use representative, real-time survey data in which respondents were asked about their situation during the COVID-19 pandemic. Our findings indicate that among the self-employed, who generally face a higher likelihood of income losses due to COVID-19 than employees, women are 35% more likely to experience income losses than their male counterparts. Conversely, we do not find a comparable gender gap among employees. Our results further suggest that the gender gap among the self-employed is largely explained by the fact that women disproportionately work in industries that are more severely affected by the COVID-19 pandemic. Our analysis of potential mechanisms reveals that women are significantly more likely to be impacted by government-imposed restrictions, i.e. the regulation of opening hours. We conclude that future policy measures intending to mitigate the consequences of such shocks should account for this considerable variation in economic hardship.
In this paper, we study the effect of exogenous global crop price changes on migration from agricultural and non-agricultural households in Sub-Saharan Africa. We show that, similar to the effect of positive local weather shocks, the effect of a locally-relevant global crop price increase on household out-migration depends on the initial household wealth. Higher international producer prices relax the budget constraint of poor agricultural households and facilitate migration. The order of magnitude of a standardized price effect is approx. one third of the standardized effect of a local weather shock. Unlike positive weather shocks, which mostly facilitate internal rural-urban migration, positive income shocks through rising producer prices only increase migration to neighboring African countries, likely due to the simultaneous decrease in real income in nearby urban areas. Finally, we show that while higher producer prices induce conflict, conflict does not play a role for the household decision to send a member as a labor migrant.
The paper investigates the question of sustainability of capacity building initiatives by reporting about the multiplication training in the frame of DIES NMT Programme on quality assurance in Uganda and how it could make use of the social capital within the existing quality assurance network to sustain and address challenges during its implementation. The purpose of the article is to explore the nature of networking (social and institutional) which was established by the Ugandan Universities Quality Assurance Forum (UUQAF) and share the strategies used in this training experience for future sustainable capacity building training initiatives in emerging economies. The paper employed a qualitative research method to describe and analyse the training framework based on primary and secondary documents.
Higher education institutions in Guinea face many challenges, including reporting responsibilities, globalisation, and massification. Institutional evaluations of higher education and research institutions in 2013 could not initiate the implementation of change processes within the institutions. Recently, however, various initiatives have been started to change this situation with the purpose to sensitise and raise awareness and capabilities for quality assurance structures in Guinean HEIs. So far, the emphasis has been put on quality enhancement in higher education, especially on teaching evaluation, curriculum development, as well as on establishing quality assurance structures. This article gives an overview of the state of play and takes stock of the activities that have been initiated to set up quality assurance mechanisms in higher education and research institutions, and presents perspectives for further development of the quality approach in Guinea. The project ‘Quality Assurance Multiplication 2017-2018’ serves as an example to describe approaches and activities in setting up stable quality assurance structures, and to strengthen and raise awareness for a ‘quality culture’.
Les établissements d’enseignement supérieur en Guinée sont confrontés à de nombreux défis, notamment les responsabilités en matière de rapports, la mondialisation et la massification. Les évaluations institutionnelles des établissements d’enseignement supérieur (EES) et de recherche en 2013 n’ont pas permis d’initier la mise en oeuvre des processus de changement au sein des établissements. Récemment, diverses initiatives ont été lancées pour changer cette situation dans le but de sensibiliser et de renforcer la prise de conscience et les capacités des structures d’assurance qualité dans les EES guinéennes. Jusqu’à présent, l’accent a été mis sur l’amélioration de la qualité dans l’enseignement supérieur, en particulier sur l’évaluation de l’enseignement, l’élaboration des programmes d’études, ainsi que sur la mise en place de structures d’assurance qualité. Cet article donne un aperçu de l’état des lieux et fait le point sur les activités qui ont été lancées pour mettre en place des mécanismes d’assurance qualité dans les établissements d’enseignement supérieur et de recherche, et présente les perspectives de développement de l›approche qualité en Guinée. Le projet «Multiplication de l’assurance qualité 2017 – 2018» sert d’exemple pour décrire les approches et les activités de mise en place de structures stables d’assurance qualité, et pour renforcer et sensibiliser à une «culture de la qualité».
Whilst providing a framework for learning and scientific emancipation, a proposal writing training is confronted with various organisational and didactic challenges, which influence the achievement of the set training objectives. Based on observations made during the workshops for proposal writing organised in Kinshasa, Democratic Republic of Congo, as part of the NMT Programme, the article raises two main questions: (a) How could these challenges be overcome and successfully addressed in the training? (b) What is the level of learning outcomes of the participants at the end of the training? The article shows that the success of the training lays in the relevance of the employed training approaches. The use of a participatory approach encouraged constructive exchanges between participants, trainers, and experts, and enabled all participants to finalise coherent projects to apply for national and international funding.
Mise en oeuvre de l’atelier d’écriture des projets de recherche en République démocratique du Congo
(2020)
Tout en offrant un cadre d’apprentissage et d’émancipation scientifique, l’atelier d’écriture des projets oppose différents défis, d’ordre organisationnel et didactique, dont les approches influent sur son déploiement et sur l’atteinte des objectifs assignés. Comment s’y prendre pour contourner ces défis et accomplir avec succès l’implémentation de la formation proposée ? Quelle en est l’incidence sur la qualité des acquisitions des participants au terme de la formation ? Le présent article répond à ces questions, partant des observations faites lors des formations organisées à Kinshasa (République démocratique du Congo) dans le cadre du programme National Multiplication Training (NMT). Il en ressort que le succès d’un atelier réside dans la pertinence des approches mises en oeuvre. Le recours à l’approche participative a favorisé les échanges constructifs entre participants, formateurs et experts, et a permis à tous les participants de finaliser des projets cohérents, pour postuler aux financements nationaux et internationaux.
We investigate how inviting students to set task-based goals affects usage of an online learning platform and course performance. We design and implement a randomized field experiment in a large mandatory economics course with blended learning elements. The low-cost treatment induces students to use the online learning system more often, more intensively, and to begin earlier with exam preparation. Treated students perform better in the course than the control group: they are 18.8% (0.20 SD) more likely to pass the exam and earn 6.7% (0.19 SD) more points on the exam. There is no evidence that treated students spend significantly more time, rather they tend to shift to more productive learning methods. The heterogeneity analysis suggests that higher treatment effects are associated with higher levels of behavioral bias but also with poor early course behavior.
This article collected the results of a qualitative study focused on Colombian Higher Education Institutions’ representatives partaking in the training ‘Internationalisation for Peacebuilding 2018’. The selected Higher Education Institutions and representatives were all located in regions acutely affected by the Colombian armed conflict, now experiencing multifaceted challenges and opportunities in a post-conflict scenario. Interviews with participants of the training were conducted to analyse the skills acquired and to identify possible improvements brought about by the training at the institutions. The article further identifies specific needs of the institutions, to be taken into account for future courses on internationalisation for higher education institutions.
During the National Multiplication Training in Kenya in 2018, participants raised concerns about attrition, completion rates and quality of PhD programmes in Kenya’s public universities. This led the authors of this article to further examine the question of PhD completion rates. Available data underlined that PhD students across various disciplines in Kenya’s public universities take unnecessarily long to complete their studies due to a myriad of factors that are related to their supervisors, university guidelines for post-graduate studies, or the students themselves. This article examines inertia areas along the PhD training pathway at three public universities in Kenya and provides suggestions on structural and operational changes universities must make to shorten completion periods.
Deans at Institutions of Higher Education are seldom recipients of effective or specific professional management training, institutional mentorship, and coaching despite an increasing demand on them to play a more dynamic leadership role in the face of ever-changing local and global challenges. To address this deficiency, the inaugural Malaysian Chapter of the International Deans’ Course (MyIDC) was held in three parts over 2019 and 2020. In this paper, findings related to feedback on the programme are presented and discussed. Responses from the participants from two sets of surveys, and written feedback provided by two IDC international trainers involved in MyIDC were analysed. These reveal potential areas of improvement for the forthcoming MyIDC programme, such as in terms of planning and organisation, duration, content, and delivery. The article explores the lessons learnt from the MyIDC 2019/2020 training programme and discusses the improvements that can be made arising from the feedback received.
The higher education structure in Malaysia has experienced significant changes since the implementation of the Private Higher Educational Institutions Act of 1996. The unprecedented expansion of the higher education sector and the increasing autonomy conferred to universities have created a huge demand for competent university leadership that supports the development of higher education in Malaysia. This article discusses the very first national multiplication training in Malaysia in 2014 and analyses such out-comes as the identification of good practices for future initiatives and applications in university leadership training.
Alles auf (Studien-)Anfang? Faktoren für den Studienerfolg in der Eingangsphase und zur Studienmitte
(2020)
Die hohen Abbruchquoten, insbesondere in der Studieneingangsphase, haben die Hochschulen in Deutschland veranlasst, eine Vielzahl von Maßnahmen zu ergreifen, über deren Wirkungen bisher allerdings wenig bekannt ist. Im vorliegenden Beitrag werden Befunde eines Forschungsprojekts speziell zur Studieneingangsphase sowie ergänzend zur Studienmitte vorgestellt, dessen Ziel es war, Bedingungen eines erfolgreichen Studieneinstiegs zu identifizieren und Empfehlungen für eine Optimierung des Studieneingangs abzuleiten. Das Forschungsdesign umfasste neben qualitativen Studien vor allem eine quantitative Längsschnittbefragung an fünf Universitäten (Potsdam, Mainz, Magdeburg, Kiel und Greifswald). Im Ergebnis der Analysen konnte die forschungsleitende Hypothese, dass Maßnahmen zum Studieneingang vor allem dann zur Erhöhung des Studienerfolgs einen Beitrag leisten, wenn sie zur akademischen und sozialen Integration in die Hochschule beitragen, bestätigt werden. Bedeutsam für den Studienerfolg sind demnach insbesondere solche Faktoren wie die Identifikation mit dem Studienfach, die Selbstwirksamkeit, die berufliche bzw. erfolgsorientierte Lernmotivation und die akademische Integration. Daneben konnte ein positiver Einfluss des sozialen Klimas sowie des Forschungs- und Praxisbezugs auf die Studienzufriedenheit nachgewiesen werden. Weiterführende Analysen zur Studienmitte verdeutlichen zudem, dass für die beiden Studienphasen (Eingang und Studienmitte) gleiche Faktoren bei zum Teil unterschiedlicher Gewichtung eine Rolle spielen. So ist die soziale Integration ein wesentlicher Prädiktor in beiden Phasen – in der Eingangsphase eher in die Studierendenschaft und im weiteren Studienverlauf (Studienmitte) eher in die akademische Gemeinschaft (in Form von Lehrenden). Insofern muss die Eingangsfrage wie folgt beantwortet werden: Ja, alles auf Anfang, aber dann mit den Bemühungen, soziale und akademische Integration aller Studierenden voll und ganz zu gewährleisten. Zudem machen die Befunde auf die bisher offenbar unterschätzte Rolle von Verwertungsmotiven aufmerksam.
Wolfenstein: The New Order
(2020)
Silent Hill 2
(2020)
Papers, Please
(2020)
Mass Effect
(2020)
Grand Theft Auto V
(2020)
Brothers: A Tale of Two Sons
(2020)
Most of the matter in the universe consists of hydrogen. The hydrogen in the intergalactic medium (IGM), the matter between the galaxies, underwent a change of its ionisation state at the epoch of reionisation, at a redshift roughly between 6>z>10, or ~10^8 years after the Big Bang. At this time, the mostly neutral hydrogen in the IGM was ionised but the source of the responsible hydrogen ionising emission remains unclear. In this thesis I discuss the most likely candidates for the emission of this ionising radiation, which are a type of galaxy called Lyman alpha emitters (LAEs). As implied by their name, they emit Lyman alpha radiation, produced after a hydrogen atom has been ionised and recombines with a free electron. The ionising radiation itself (also called Lyman continuum emission) which is needed for this process inside the LAEs could also be responsible for ionising the IGM around those galaxies at the epoch of reionisation, given that enough Lyman continuum escapes. Through this mechanism, Lyman alpha and Lyman continuum radiation are closely linked and are both studied to better understand the properties of high redshift galaxies and the reionisation state of the universe.
Before I can analyse their Lyman alpha emission lines and the escape of Lyman continuum emission from them, the first step is the detection and correct classification of LAEs in integral field spectroscopic data, specifically taken with the Multi-Unit Spectroscopic Explorer (MUSE). After detecting emission line objects in the MUSE data, the task of classifying them and determining their redshift is performed with the graphical user interface QtClassify, which I developed during the work on this thesis. It uses the strength of the combination of spectroscopic and photometric information that integral field spectroscopy offers to enable the user to quickly identify the nature of the detected emission lines. The reliable classification of LAEs and determination of their redshifts is a crucial first step towards an analysis of their properties.
Through radiative transfer processes, the properties of the neutral hydrogen clouds in and around LAEs are imprinted on the shape of the Lyman alpha line. Thus after identifying the LAEs in the MUSE data, I analyse the properties of the Lyman alpha emission line, such as the equivalent width (EW) distribution, the asymmetry and width of the line as well as the double peak fraction. I challenge the common method of displaying EW distributions as histograms without taking the limits of the survey into account and construct a more independent EW distribution function that better reflects the properties of the underlying population of galaxies. I illustrate this by comparing the fraction of high EW objects between the two surveys MUSE-Wide and MUSE-Deep, both consisting of MUSE pointings (each with the size of one square arcminute) of different depths. In the 60 MUSE-Wide fields of one hour exposure time I find a fraction of objects with extreme EWs above EW_0>240A of ~20%, while in the MUSE-Deep fields (9 fields with an exposure time of 10 hours and one with an exposure time of 31 hours) I find a fraction of only ~1%, which is due to the differences in the limiting line flux of the surveys. The highest EW I measure is EW_0 = 600.63 +- 110A, which hints at an unusual underlying stellar population, possibly with a very low metallicity.
With the knowledge of the redshifts and positions of the LAEs detected in the MUSE-Wide survey, I also look for Lyman continuum emission coming from these galaxies and analyse the connection between Lyman continuum emission and Lyman alpha emission. I use ancillary Hubble Space Telescope (HST) broadband photometry in the bands that contain the Lyman continuum and find six Lyman continuum leaker candidates. To test whether the Lyman continuum emission of LAEs is coming only from those individual objects or the whole population, I select LAEs that are most promising for the detection of Lyman continuum emission, based on their rest-frame UV continuum and Lyman alpha line shape properties. After this selection, I stack the broadband data of the resulting sample and detect a signal in Lyman continuum with a significance of S/N = 5.5, pointing towards a Lyman continuum escape fraction of ~80%. If the signal is reliable, it strongly favours LAEs as the providers of the hydrogen ionising emission at the epoch of reionisation and beyond.
Der Beitrag befasst sich mit der Möglichkeit, Computerspiele aufgrund der bildlichen Stilmittel parallel zu Entwicklungen der Kunstgeschichte zu untersuchen. Hierzu wird auf die Stilanalyse des Schweizer Kunstwissenschaftlers Heinrich Wölfflin zurückgegriffen, der den Wandel der realistischen Malerei von der Renaissance zum Barock am Übergang von ‚flachen‘ zu ‚tiefen‘ Darstellungen festmacht. In einem zeitlich wesentlich kürzeren Abstand lässt sich die gleiche Veränderung am Übergang früher realistischer Computerspiele vom Anfang der 1990er Jahre bis zu den 2000er Jahren feststellen. Damit zeigt sich sowohl die Relevanz der kunstgeschichtlichen Auseinandersetzung mit Computerspielen, wie sich auch eine neue Perspektive auf die Frage nach digitalen Spielen ‚als Kunst‘ eröffnet.
Der Beitrag beschäftigt sich mit dem Potential von Computerspielen für den Politikunterricht. Im Mittelpunkt steht die Frage, ob sich die Politiksimulation DEMOCRACY 3 für einen Einsatz in der gymnasialen Oberstufe eignet. Es wird herausgearbeitet, dass sich die Spieler von DEMOCRACY 3 mit den Auswirkungen politischer Entscheidungen auf die ökonomische, soziale und kulturelle Lage eines westlichen Landes auseinandersetzen, während die Komplexität politischer Aushandlungs- und Entscheidungsprozesse in demokratischen Regierungssystemen nicht erfahrbar wird. Die hier festgestellte Unvollständigkeit der politischen Simulation wird für die pädagogische Praxis aber nicht nur als Problem, sondern vor allem auch als didaktische Chance gesehen. Denn es sind gerade die Leer- und Schwachstellen der Simulation des Spieles, die besondere Anknüpfungsmöglichkeiten für den Unterricht bieten, da sie eine kritische Analyse der Simulation bzw. einen Vergleich mit der Realität politischer Prozesse und damit eine tiefe Auseinandersetzung mit Politik im Allgemeinen herausfordern. Schließlich werden drei konkrete Ideen für die schulische Praxis vorgestellt.
Die Geschichte lebt!
(2020)
In „Die Geschichte lebt!“ skizziert der Autor fünf wichtige Prämissen zur erfolgreichen Entwicklung didaktischer Spielformen. Auf Basis seiner eigenen Tätigkeit als Game Designer exemplifiziert er diese anhand eigener digitaler und analoger Spielformen und erklärt anschaulich das eigene Vorgehen bei der Entwicklung von Serious Games und Lernspielen.
Nach einer Einführung in die Geschichte der Strategiespiele und im Speziellen von 4X-Spielen wird das Phänomen der „Hands-off-Games“ erläutert. Im Anschluss wird ein Vorschlag unterbreitet, wie 4X-Geschichtsspiele im Unterricht eingesetzt werden können. Dabei soll ein 4X-Strategiespiel zu einem historischen Thema entworfen werden. Die Modellierung erfolgt in drei Arbeitsschritten: Themenfindung, Modellfindung, Parametrierung. In den Entwurf des Modells fließen viele Überlegungen ein, die zentrale Fragen der Gemeinschaftskunde betreffen.
An der BTU finden freiwillige Kurse zur Studienvorbereitung, im Rahmen des BMBF geförderten Projektes „Blended Learning Anfangshürden erkennen zur Unterstützung der fachspezifischen Studienvorbereitung und des Lernerfolges im ersten Studienjahr“, statt. Die Kluft zwischen notwendigen und tatsächlich vorhandenen Fähigkeiten ist in der Mathematik bei vielen angehenden Studierenden groß und die zur Verfügung stehende Zeit oft zu gering. Hier setzt dieses Konzept an. Neben Präsenzveranstaltungen enthält der Kurs unterstützte Selbstlernphasen. Diese werden durch einen virtuellen Kursraum und einer Anwendung für mobile Endgeräte (App) unterstützt.
Das gesteckte Ziel unserer Applikation ist es nicht nur die ständige Verfügbarkeit von Lernmaterialien zu ermöglichen, sondern auch die gesamte Kommunikation zwischen Dozenten und Studierenden, sowie Studierende unter sich, zu verändern. Eine Mischung aus E-Learning, Blended-Learning und Mobile- Learning soll es hier allen Teilnehmer ermöglichen, ortsungebunden zu agieren. Neue Funktionen sollen es den Studierenden ermöglichen, besser miteinander zu arbeiten, zu kooperieren und neue Bekanntschaften zu schließen.
Der vorliegende Beitrag befasst sich mit der Konstruktion eines Lehr-/ Lernszenarios polyvalenter Grundlagenvorlesungen in naturwissenschaftlichen Fachwissenschaften. Das Szenario verbindet klassische Vorlesungen mit virtuellen Elementen wie Online-Kursen, Online-Foren und Audience-Response-Systemen sowie dem Arbeiten in Kleingruppen mit Ansätzen des problemorientierten Lernens. Ziel ist es das Grundlagenwissen der Studierenden anzupassen, das Arbeiten in Gruppen zu fördern und problemorientiertes Lernen zu erlernen.
Bewegunglesen.com
(2014)
bewegunglesen.com (mit Silber bei den Best of Swiss Web Awards 2013 ausgezeichnet) ist ein E-Learning-Tool und bietet für Sportunterrichtende und Studierende eine webbasierte, interaktive Übungsgelegenheit, die Bewegungsanalyse und das kriteriengeleitete Verbessern von Fertigkeiten zu erlernen. Bewegungsabläufe mit ihren Kernbewegungen werden praxisnah und schulstufengerecht vermittelt. Daneben können auch Unterrichtsvideos hochgeladen, geschnitten, durch Grafiken und Fakten angereichert und innerhalb der Community geteilt werden. Aus den Clips lassen sich Übungen und Prüfungen mit Beurteilungskriterien des Bewegungsablaufs zusammenstellen, welche automatisiert ausgewertet werden.
Bei der hier vorgestellten Anwendung handelt es sich um den Prototypen einer webbasierten Applikation zur Analyse von Nutzungsdaten der AnwenderInnen von eLearning-Angeboten. Die Applikation wurde dabei explizit für unterschiedliche Zielgruppen wie eLearning-AnbieterInnen, Lehrende und WissenschaftlerInnen entworfen. Die Anwendung kann Daten verschiedener Lernplattformen auswerten und nutzt hierbei Methoden des Educational Data Mining. Sie unterstützt dabei sowohl klassische Plattformen mit personalisiertem Zugang sowie offene Plattformen, deren Angebote ohne Registrierung zugänglich sind.