Calculation, simulation, and experimental analysis of distorted and enhanced spectra from attenuated total reflection (ATR)

This doctoral thesis extensively investigates the principles, calculations, experiments, and simulations related to the distortion spectrum and surface-enhanced spectroscopy within the framework of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The research encompasses four main aspects: 1. Based on Maxwell's equations, an in-depth exploration is conducted into the origins of spectral distortion with computations utilizing Snell's law. The combination of the established model with Fresnel’s equation yields simulation outcomes that align with the experimental spectral data. Correction of the distortion spectrum is realized through the application of the Kramers-Kronig (KK) transform and an algorithm resembling the Fourier transform (FT). The subsequent analysis challenges conventional understanding by revealing the blue shift associated with the degree of spectral distortion. 2. The study systematically introduces the transition from Fourier Transform (FT) methodologies to contemporary deep learning algorithms, particularly neural networks. Recognizing the intrinsic complexity of conventional correction methods, the investigation performs the classification and correction of distorted spectra using artificial neural network algorithms. Comparative assessments with traditional methods indicate that long short-term memory (LSTM) and Transformer models exhibit accelerated processing speeds and heightened batch correction capabilities. 3. Theoretical calculations for surface plasmon generation, accounting for the thickness of the thin layer, were conducted. The surface enhancement spectrum of Pd nanoparticles is demonstrated through the integration of theoretical calculations with experiments. 4. The thesis expounds on the principles of two-dimensional Fourier transform (2D FT) and provides an in-depth analysis of the classification and fundamental principles of two-dimensional infrared spectroscopy (2D IR). As a technique rooted in third-order nonlinear optical phenomena, 2D IR spectroscopy exhibits distortion and surface-enhanced spectroscopy characteristics similar to those observed in one-dimensional (1D) spectroscopy, particularly near the critical angle. Furthermore, due to the unique principles of 2D IR, it also demonstrates enhanced specificity at the Brewster angle. This thesis offers a comprehensive discussion and comparison of the similarities and differences between 1D and 2D surface-enhanced spectroscopy

Towards coupling agent-free composites made from regenerated cellulose/HDPE by UV radiation-induced cross-linking

This research aims to enhance fibre-matrix adhesion in bio-based fibre-reinforced polyolefins without using adhesion promoters. The primary focus is to establish a cross-linking mechanism between cellulose fibres and polyethylene by applying UV irradiation to a UV-transparent matrix and UV-absorbing fibres. The influence of UV treatment on the composite properties is evaluated by tensile, interfacial and interlaminar shear strength tests. The UV irradiation decreases the critical fragment length in single fibre fragmentation tests, indicating an improved fibre-matrix adhesion. The UV-irradiated composites’ tensile strength and Young’s modulus are found to be ~10% (for 3- and 8-minute irradiation) and ~50% (for 8-minute irradiation), respectively, higher than those of the untreated samples. Furthermore, the UV irradiation leads to an improvement in the interlaminar shear strength by 25%. The variation of the UV-irradiation time (3 min and 8 min) and the comparison of the properties of semi-finished composite sheets and composites also reveal chemical and physical changes in the regenerated cellulose fibres due to heat adsorption. The proposed mechanism of interfacial crosslinking is confirmed by FTIR spectroscopy. The results suggest an approach to overcome poor compatibility between hydrophobic polyolefin matrix and hydrophilic cellulose-based fibres, resulting in adhesive-free bio-based composites

Regisseure des Reiseglücks. Berufsfeld Reiseleitung: Rahmenbedingungen, Erfahrungen und Perspektiven

Die Studie liefert eine Bestandsaufnahme auf qualitativer Basis zum Berufsfeld Reiseleitung. Sie wurde im Jahr 2006 an der Hochschule Bremen durchgeführt und stützt sich auf 30 Interviews. Die Sichtweise der Akteure auf das Feld spiegelt sich in den Antworten der Befragten. Die Ergebnisse zeigen das hohe Engagement vieler Reiseleiter und die immer noch kritische berufliche Absicherung

Healthy eating in the context of social inequalities: The influence of socioeconomic factors on attitudes and dietary behavior

Soziale Ungleichheiten im Ernährungsverhalten sind eine wesentliche Ursache gesundheitlicher Ungleichheiten. Einstellungen zur gesunden Ernährung beeinflussen das Ernährungsverhalten, wobei sozioökonomische Unterschiede bestehen. Ein besseres Verständnis dieser Zusammenhänge ist entscheidend für gezielte Interventionen. Diese kumultative Dissertation untersucht Einstellungen zur gesunden Ernährung, ihren Einfluss auf das Ernährungsverhalten und die Rolle sozioökonomischer Faktoren anhand eines systematischen Reviews und zweier Sekundäranalysen bevölkerungsbasierter Daten aus Deutschland und Europa. Die Ergebnisse zeigen, dass i) die Allgemeinbevölkerung unterschiedliche Perspektiven zur (gesunden) Ernährung hat, ii) sozioökonomische Unterschiede in diesen Bedeutungen bestehen, iii) niedrigere sozioökonomische Gruppen ungünstigere Ernährungsverhaltensweisen zeigen, iv) positive ernährungsbezogene Einstellungen die Ernährungsqualität verbessern und v) diese Einstellungen als vermittelnder Faktor zwischen sozioökonomischem Status und Ernährungsverhalten wirken. Damit bestätigen die Ergebnisse sozial-kognitive Verhaltenstheorien, wonach Einstellungen das Ernährungsverhalten maßgeblich beeinflussen. Für Forschung und Praxis ergeben sich daraus wichtige Implikationen. Zukünftige Studien sollten intersektionale Perspektiven einbeziehen, um Gruppen mit besonderem Bedarf an Ernährungsinterventionen zu identifizieren. Zudem ist eine einheitliche Erfassung ernährungsbezogener Einstellungen im Zusammenhang mit sozioökonomischen Faktoren entscheidend. Um soziale Unterschiede im Ernährungsverhalten besser zu verstehen, sollten weitere Mediatoren untersucht werden. Die Ergebnisse verdeutlichen den Bedarf an Interventionen, die Ernährungswissen und -kompetenzen fördern sowie eine positive Wahrnehmung gesunder Ernährung stärken. Besondere Berücksichtigung sollten die Bedürfnisse sozioökonomisch benachteiligter Gruppen finden, um Ungleichheiten zu reduzieren

The Immigrant Social Rights Data Set (ImmigSR). Technical Report (2., aktualisierte Ausgabe, Stand: 04.03.2025)

This Technical Report for the Immigrant Social Rights (ImmigSR) (formerly the Migrant Social Protection, MigSP) Dataset outlines the conceptualization and operationalization of immigrant social rights, details the data collection and presents the dataset’s codebook. The data provide a set of quantitative comparative measures of de jure immigrant social rights regarding social assistance, unemployment insurance, child benefits, social pensions and employment injury benefits in 45 countries across Europe, Latin America, North America, Oceania and Southeast Asia for the years 1980-2021. The second wave of the data includes several key expansions. First, the dataset was expanded to include six additional countries for the years 2000–2021. Second, data for existing countries was extended to cover the years 2019–2021. Third, two legal categories of migrants were added across all countries: seasonal migrant workers and family migrants. Fourth, three types of benefits were introduced: social pensions, employment injury benefits, and child or family benefits. ImmigSR builds on data collected during the first phase of the Collaborative Research Center Global Dynamics of Social Policy at the University of Bremen, and expands data collected within the realm of the Immigration Policies in Comparison Project (IMPIC) (Bjerre et al., 2016; Helbling et al., 2017).Deutsche Forschungsgemeinschaft (DFG)1

Disentangling democracy: What furthers immigrant social rights?

Immigrant rights have been found to be better protected in democracies than in authoritarian regimes, but there is no systematic test of different explanations of why this is the case. In this paper, we attempt to fill this gap by investigating which features of democratic political systems are conducive to a subset of immigrants’ rights, namely social rights. Drawing on literatures on human rights, minority rights, and immigrants’ rights, we hypothesize that whereas electoral elements are not necessarily conducive to immigrant social rights, liberal democratic institutions and civil society participation are. To test these hypotheses, we analyze data on immigrant social rights that spans the years 1980 to 2018 and covers 38 countries around the world using fixed effects models. The level of democracy and several subcomponents thereof are measured using indices provided by the V-Dem project. Descriptively, democracies indeed grant immigrants more social rights than autocracies. However, the multivariate analyses show that disaggregating democracy indices is important. The most aggregate index of liberal democracy had no significant association with the outcome variable. When disaggregating, we found that also the electoral component has no robust effect on immigrant social rights, but the liberal and the civil society components are drivers of extensions of immigrant social rights.Deutsche Forschungsgemeinschaft (DFG)3

Death is a great Secret. Background and impulses for school teaching with regard to the children's book "Farewell to grandfather Elephant"

„Der Tod ist ein großes Geheimnis“, sagte der Elefantengroßvater. Spazierengehen auf Wolken, Musizieren mit Engeln, Kartenspielen in der Hölle, Weiterleben als Schmetterling, Wiedergeburt als Elefant oder vielleicht doch nur die körperliche Vergänglichkeit – Vorstellungen von Schüler:innen zu der Frage, was denn eigentlich nach dem Tod kommt, sind vielfältig. Sie lassen sich als Postmortalitätsvorstellungen beschreiben, die sich aus Vorstellungen verschiedener religiöser und kultureller Einflüsse speisen und individuell entwickeln. Ebendiese Postmortalitätsvorstellungen, die sich in der europäischen Geschichte bis heute finden lassen, beschreiben Isabel Abedi (Text) und Miriam Cordes (Bild) in ihrem Bilderbuch Abschied von Opa Elefant. Die vorliegende Veröffentlichung stellt die fachlichen und fachdidaktischen Hintergründe dar, insbesondere zu Postmortalitätsvorstellungen in der europäischen Geschichte und in der Entwicklung bei Kindern und Jugendlichen. Auf dieser Basis werden Vorschläge zur Erarbeitung des Bilderbuches Abschied von Opa Elefant im Unterricht gemacht und die dazugehörigen Materialien entwickelt.16

Using decision trees to identify intersectional subgroups at risk for cancer screening non-attendance: three European case studies

As in many relevant public health areas, attendance in cancer screening programs is stratified by social dimensions, yet current additive approaches fail to capture the complexity of discrimination leading to health inequalities. In fact, social dimensions interact, shaping experiences of discrimination in accessing cancer screening. This dissertation advances the study of complex social inequalities by developing different analytical strategies that explore the use of decision trees under the framework of intersectionality to identify subgroups at risk of non-attendance. Three European case studies were analysed: breast cancer screening (BCS) in Germany, BCS in Spain, and colorectal cancer (CRC) screening in Sweden. Three analytical strategies were explored: (i) comparing decision tree-based and evidence-informed approaches (BCS Germany), (ii) using decision trees to reduce intersectional complexity (CRC Sweden), and (iii) employing decision trees as predictive tools (BCS Spain). Findings reveal key Individual-regional interactions. In Spain, regions significantly influenced BCS attendance, reflecting economic disparities and screening program timelines. In Germany, partnership cohabitation was a protective factor, while certain regions had higher non-attendance risks. In Sweden, organized screening programs mitigated inequalities, while opportunistic screening revealed disparities based on gender, migration background, and income. This dissertation contributes to identifying intersectional subgroups at risk of non-attendance by inductively selecting social dimensions and modelling non-linear and nuanced interactions between categories across subgroups. It also advances the methodological field of quantitative intersectionality by proposing decision trees to simplify intersectional complexity, improving results' interpretability. Overall, it enhances understanding of cancer screening inequalities and proposes methodological tools for public health research

Ecophysiology of Red Sea Corals in Response to Carbon and Nitrogen Availabilities

Carbon (C) and nitrogen (N) are essential for coral health, growth and energy production. Yet, maintaining a balanced availability of these elements is critical, as both deficiencies and excesses can have negative consequences for coral survival. This thesis explores how key Red Sea coral taxa, including reef-forming hard corals and a dominant soft coral species, respond to C and N availability, providing insights into their ecophysiology and resilience to environmental challenges such as nutrient pollution. Research Question 1 explored the ecophysiological responses of Red Sea corals to natural C fluxes, as detailed in Chapters 2 and 4. Chapter 2 showed that Xenia umbellata’s physiology was negatively impacted by the absence of heterotrophic food, reducing pulsation rates, symbiont density, and mitotic index, though the coral compensated by increasing symbiont chlorophyll-a content. Water flow had no significant effect, likely due to its pulsation-driven flow regulation. Chapter 4 revealed that azooxanthellate corals like Tubastraea coccinea exhibited significantly higher denitrification rates than zooxanthellate species, as denitrifiers utilised environmental C (e.g., DOC), instead of relying solely on photosynthates. High DOC availability (in addition to other environmental and physiological factors) was identified as one of the key drivers of denitrification in Acropora spp., Millepora dichotoma and Tubastrea coccinea, highlighting the role of C in N cycling processes in corals. These findings emphasise the critical role of both autotrophic and heterotrophic strategies in corals' responses to natural variations in C availability and its influence on biogeochemical processes like denitrification. Research Question 2 investigated the ecophysiological responses of Xenia umbellata to excess C availability under eutrophic conditions, as explored in Chapter 3. The study found that excess organic matter (OM) at 20 mg C L-1, provided as dissolved organic matter (DOM) had no negative effect on coral ecophysiology. However, particulate organic matter (POM) in the form of phytoplankton and zooplankton, caused significant damage, including impaired feeding tentacles, reduced pulsation rates, and increased mortality. The severity of these effects was primarily linked to POM dosage, rather than particle size, highlighting X. umbellata’s vulnerability to coastal eutrophication, where excess POM can harm its ecophysiology. Research Question 3 explored the ecophysiological responses of Red Sea corals to natural fluctuations in N availability, addressed in Chapter 4. High ammonium levels drive denitrification in Acropora spp., as ammonium supports nitrification and nitrate production, a key substrate for denitrifying bacteria. Unexpectedly, T. coccinea showed elevated denitrification under low nitrate availability, likely due to co-occurring N2 fixation and denitrification, characteristic of oligotrophic Red Sea conditions. These results emphasize that coral responses to N fluxes are highly species-specific and influenced by local nutrient dynamics, underscoring the need to consider both biological and environmental variability when assessing coral reef resilience. This thesis highlights Xenia umbellata’s adaptability to low C availability and variable flow but reveals its vulnerability to excess C inputs, exposing soft corals to anthropogenic threats. Species with higher heterotrophic capacities may better withstand inorganic N pollution, potentially driving shifts toward heterotrophic-dominated reefs with significant biodiversity and ecosystem implications. This thesis offers critical insights into the physiological responses of Red Sea corals to ambient and excess nutrient levels, helping to predict reef resilience and shifts in community composition. The findings provide a basis for targeted management strategies to mitigate nutrient-related stress, especially in light of expanding coastal development projects in the Central Red Sea region

Die neue generalistische Pflegeausbildung in Bremen

Die seit 2020 umgesetzte "generalistische" Pflegefachkraftausbildung führt drei zuvor getrennte Fachkraftabschlüsse zu einem gemeinsamen Abschluss zusammen.Die neue Pflegeausbildung ist dadurch inhaltlich und organisatorisch sowie in den Lernanforderungen komplexer geworden. Die vorliegende Studie hat aus einer arbeitswissenschaftlichen Perspektive untersucht, welche Auswirkungen die Reform im Land Bremen auf die Ausbildungsqualität als wichtige Variable für den Ausbldungserfolg der Pflegeauszubildenden hat.4