Multimodal Imaging Unveils the Hidden Dimensions of Plant Physiology: From Metabolic Landscapes to Mechanistic Insights

Bilder sagen mehr als tausend Worte. Die Einführung von Mikroskopen in der Geschichte der Naturwissenschaften eröffnete Einblicke in neue Dimensionen. Modernere bildgebende Verfahren wie Infrarot (IR) und Kernspinresonanz (NMR) ermöglichen es uns, die Grenzen des Sichtbaren noch weiter zu verschieben. Zusätzlich erweitern Computertools die Analyse komplexer Bilddaten. In dieser Dissertation beschreibe ich meine Arbeit an dekonvolutionellem Data Mining in Kapitel 2.1, um die Bildgebung mehrerer Metabolite mit einer einzigen Plattform, der Infrarotbildgebung, zu ermöglichen. Diese Strategie ermöglicht es, die Assimilatverteilung wichtiger Transport- und Speicherverbindungen zu verstehen und bietet einen Fahrplan für die quantitative Analyse solcher IR-Bilder. Das Zusammenspiel von Physik und Chemie insbesondere in biologischen Systemen stellt eine besondere Herausforderung dar, sowohl für die Erfassung als auch für die Interpretation resultierender Daten. Pflanzen sind komplexer als man denkt. Sie bestehen aus einem Mosaik an Geweben und jedes leistet seinen spezifischen Beitrag zur Gesamtfunktion der Pflanze. Gewebe beherbergen verschiedene Zelltypen und erfüllen unterschiedlichste Funktionen, egal ob tot oder lebendig. Imaging ist unverzichtbar, um die Verteilungsvielfalt von Stoffen innerhalb dieser aufzuklären. Durch destruktive Beprobung, die oft sensitivere und selektivere Analytnachweise erlaubt, gehen häufig topografische Beziehungen verloren. Kapitel 2.2 zeigt, wie solche Daten wieder in einen topografischen Kontext gesetzt werden können. Diese Fallstudie zeigt, wie Exsudate mithilfe eines multimodalen Ansatzes aus Massenspektroskopie und IR-Bildgebung zu ihren ursprünglichen Geweberegionen zurückverfolgt werden können, um Einblicke in ihre Funktionen zu erhalten. Die computergestützte Modellierung der Pflanzenphysiologie kann Einblicke in die Chemie der Zellwände liefern und Schlussfolgerungen hinsichtlich der mechanischen Stabilität der Internodien in Gräsern gegen externe mechanische Einflüsse erbringen (Kapitel 2.3). Durch die Integration eines mechanischen Modells der Gefäßstruktur mit ihrer Chemie beleuchtet diese Arbeit die Komplexität des Aufbaus struktureller Ressourcen und verknüpft ihre genetische Regulierung durch KASP-Marker mit nachvollziehbaren spektralen Eigenschaften und physikalischen Reaktionen. Letztendlich wollen wir wissen, wie Assimilate dorthin gelangen, wo sie hinsollen. Der letzte Abschnitt des Assimilat Weges wird durch das maternal-filiale Übergangsgewebe zwischen Phloem und Endosperm geregelt. Seine Rolle in der Metabolitübertragung wird hier anhand zweier wichtiger Aspekte beleuchtet. Erstens geht es um die Doppelrolle des wichtigen Saccharosetransporters SWEET11b bei der Zuteilung von Zuckern und Zytokinin in Gerstenkörnern (Kapitel 2.4). Die chemische Bildgebung machte einen Gradienten in der Zytokininverteilung sichtbar und bewies dessen topografischen Zusammenhang mit Saccharosetransport während der Samenfüllung. Zweitens sind der programmierte Zelltod und vakuoläre Verarbeitungsenzyme (VPE2) an der Assimilatfreisetzung aus der nuzellaren Projektion in das flüssige Endosperm beteiligt (Kapitel 2.5). Eine detaillierte Analyse von Mutanten und Transgenen hilft dabei, regulatorische Mechanismen zu identifizieren. Diese Studien zeigen die Leistungsfähigkeit fortschrittlicher Bildgebungsverfahren, die Geheimnisse der Pflanzenentwicklung zu entschlüsseln (Kapitel 2.6). Es zeigt sich das Veränderungen im Samen weitreichende Folgen in der gesamten Pflanze nach sich ziehen (Kapitel 3.1). Diese Entdeckung unterstreicht die Notwendigkeit, lokale Veränderungen im globalen Rahmen der internen Pflanzenfunktion zu untersuchen. Solche Strategien werden es uns ermöglichen, regulatorische Reaktionen an unvorhergesehenen Orten zu identifizieren und unser Verständnis der beteiligten Mechanismen zu verbessern, die das Sink-Source-Zusammenspiel steuern.Images are worth a thousand words. The microscope marked a revolutionary moment in the history of natural sciences, and contemporary technologies like infrared (IR) and nuclear magnetic resonance (NMR) now enable us to explore the previously invisible in images. Computational tools allow in-depth analysis of intricate image data. The combined use of techniques such as IR and NMR Imaging, alongside molecular and metabolic tools, provides a powerful approach to understanding plant physiology (Chapter 2.6). I want to show you a comprehensive journey through the process of image acquisition and analysis. By describing deconvolutional data mining, I can show you how to enable imaging of multiple metabolites using a single infrared platform (Chapter 2.1). This strategy allows us to understand the assimilate allocation of major transport and storage compounds and offers a road map to analyse such IR images quantitatively. The complex interplay between physics and chemistry, especially in biological systems, presents a challenge for acquiring and interpreting the resulting data. Plants present a remarkable complexity, featuring a mosaic of diverse tissues and cells, each with their unique roles contributing to the overall functioning of the plant. Even seemingly inert cell tissues serve vital purposes. Imaging techniques are indispensable for unravelling the spatial variations within plants. Often, we lose topographical relations due to destructive sampling. Abstract chemical clusters can be defined by more sensitive non-topographic analytics and imaged even if single analytes tend to fall below their detection limit. Chapter 2.2 provides an insight into how exudate composition can be traced back to their original source tissues by a multimodal approach of mass spectrometry and IR imaging to provide a better context of composition and function. Computational modelling of plant physiology can provide insights into the chemistry of cell walls and derive conclusions with respect to the mechanical stability of the internodes in grasses against lodging. By integrating a mechanical model of the vascular structure with its chemistry, this work sheds light on the complexity of structural resource buildup and links its genetic regulation through KASP markers to traceable spectral characteristics and physical response (Chapter 2.3). Finally, we want to know how assimilates get where they are supposed to be. The terminal part of the assimilate allocation pathway is controlled by the post-phloem maternal filial transition tissues. Its functional role in metabolite delivery from maternal to filial organs is vital for developing seeds. This work focuses on two crucial aspects that require particular attention. First is the dual role of an important sucrose transporter SWEET11b in the allocation of sugars and cytokinin in barley grain (Chapter 2.4). Chemical imaging visualised a gradient in cytokinin distribution and evidenced its topographical link to sucrose gradients during grain filling. Second is the involvement of programmed cell death and vacuolar processing enzymes (VPE2) in assimilate release from the nucellar projection into the endosperm cavity (Chapter 2.5). Detailed analysis of mutants and transgenics helps to generate mechanistic views of the complex story. All of these studies highlight the power of advanced imaging technologies to unlock the secrets of plant development (Chapter 2.6). The whole plant will be affected in its distribution of sugars, as exemplified by the manipulation of maternal-filial interactions in seeds (Chapter 3.1). This discovery highlights the need to study local changes within a global framework of internal plant function. Such a strategy will enable us to identify regulatory responses in unforeseen locations and enhance our comprehension of the mechanisms that govern the sink-source relationships

Concept for the Identification of Applications for Paradigm-Shifting Technologies on the Example of Quantum Computing

In this paper, the challenge of identifying high-value applications of quantum computing is examined. Although quantum computing holds enormous potential, it requires significant investments and development efforts. Therefore, it is crucial to define precise applications that can guide its development for an efficient industrialization process. To accomplish this goal, a methodology that systematically identifies and evaluates potential applications of quantum is developed. The methodology is designed for a strong alignment between tasks and technology, identification of problem and solution types, a systematic process for identifying problems, and a focus on socioeconomic challenges. It is structured according to the TRIZ methodology and comprises five submodels to determine socioeconomic applications for quantum computing

Do Recall Elections Undermine Political Support? Insights from the Recall of the Mayor of Frankfurt in 2022

Concerns about the impact of recall referendums on political support have not been empirically examined so far. For this purpose, we conducted a postelection survey of around 800 respondents in Frankfurt after the mayoral election in March 2023 which followed a successful recall in November 2022. First, there is overwhelming support for recall elections, with 87% of respondents in favour. Even supporters of the recalled candidate rarely dislike the instrument and see little need for electoral reform. Second, only a few respondents are concerned about the impact of recalls on political support, but when they are, it often leads them to disapprove of recalls. Third, political support by the recall electoral losers – as measured by satisfaction with democracy and turnout in the successor election – is at worst only slightly reduced. Taken together, these findings do not suggest that recalls damage people’s views of the political system

Development of target antigen-displaying virus-like particles (VLPs) for the generation of antibodies using hybridoma technology

Formaldehyde-fixed, paraffin-embedded (FFPE) cell and tissue samples are of great importance for immunohistochemical studies of histological specimens. However, antibodies for FFPE samples pose a challenge to antibody discovery as current immunization strategies rely predominantly on soluble proteins that cannot adequately reflect the changes in target antigens during the FFPE process. Enveloped virus-like particles (VLPs) allow for the presentation of membrane-anchored target antigens on the VLP surface and elicit a strong target antigen-specific antibody response after immunization. This proof-of-concept study presents a novel FFPE-like fixation methodology for VLP preparation aiming at the generation of FFPE-compatible monoclonal antibodies (mAbs). Human 293-F-derived VLP-producing suspension cell pools were established to produce human immunodeficiency virus (HIV)-like particles decorated with the truncated human low affinity nerve growth factor receptor (trNGFR) as model antigen. The trNGFR antigen was efficiently incorporated into VLPs with an average of 284 } 24 trNGFR molecules per VLP. To develop a fixation protocol applicable to VLPs, trNGFR-expressing cells were subjected to a variety of fixation treatments. Changes in epitopes introduced by fixation were monitored using two mAbs recognizing either an epitope present in native NGFR or an epitope present in native and FFPE NGFR. The novel simplified fixation procedure consisted of only formaldehyde and 90 °C heat fixation (FF90). Transmission electron microscopic and dynamic light scattering analysis of FF90 VLPs revealed that the fixed VLPs withstood the FF90 treatment and showed no morphological changes, allowing for the FF90 trNGFR-VLPs to be used to immunize mice for hybridoma cell generation. Hybridoma clones were screened for mAbs specifically recognizing native, FF90 and FFPE trNGFR-expressing cells in a flow cytometric assay. The isolated hybridoma mAbs did not recognize native epitopes but were reactive with FF90 and FFPE epitopes. The use of FF90-trNGFR VLPs for immunization led to the discovery of nine FFPE-NGFR-specific mAbs. This proofof-concept study demonstrated that FF90-treated VLPs decorated with a membrane-anchored target antigen are suitable antigens to preferentially generate FFPE-compatible mAbs. The FF90-VLP platform should be useful for the future discovery of specific mAbs directed against a variety of FFPE cell surface antigens

Quantum-Classical hybrid systems and their quasifree transformations

The focus of this work is the description of a framework for quantum-classical hybrid systems. The main emphasis lies on continuous variable systems described by canonical commutation relations and, more precisely, the quasifree case. Here, we are going to solve two main tasks: The first is to rigorously define spaces of states and observables, which are naturally connected within the general structure. Secondly, we want to describe quasifree channels for which both the Schrödinger picture and the Heisenberg picture are well defined. We start with a general introduction to operator algebras and algebraic quantum theory. Thereby, we highlight some of the mathematical details that are often taken for granted while working with purely quantum systems. Consequently, we discuss several possibilities and their advantages respectively disadvantages in describing classical systems analogously to the quantum formalism. The key takeaway is that there is no candidate for a classical state space or observable algebra that can be put easily alongside a quantum system to form a hybrid and simultaneously fulfills all of our requirements for such a partially quantum and partially classical system. Although these straightforward hybrid systems are not sufficient enough to represent a general approach, we use one of the candidates to prove an intermediate result, which showcases the advantages of a consequent hybrid ansatz: We provide a hybrid generalization of classical diffusion generators where the exchange of information between the classical and the quantum side is controlled by the induced noise on the quantum system. Then, we present solutions for our initial tasks. We start with a CCR-algebra where some variables may commute with all others and hence generate a classical subsystem. After clarifying the necessary representations, our hybrid states are given by continuous characteristic functions, and the according state space is equal to the state space of a non-unital C*-algebra. While this C*-algebra is not a suitable candidate for an observable algebra itself, we describe several possible subsets in its bidual which can serve this purpose. They can be more easily characterized and will also allow for a straightforward definition of a proper Heisenberg picture. The subsets are given by operator-valued functions on the classical phase space with varying degrees of regularity, such as universal measurability or strong*-continuity. We describe quasifree channels and their properties, including a state-channel correspondence, a factorization theorem, and some basic physical operations. All this works solely on the assumption of a quasifree system, but we also show that the more famous subclass of Gaussian systems fits well within this formulation and behaves as expected

Untersuchung der Laser-induzierten Zerstörschwelle von Strahlführungskomponenten zur Ausarbeitung materialspezifischer Messroutinen

Moderne optische Strahlführungssysteme werden für zahlreiche Laseranwendungen benötigt. Diese Systeme können sowohl aus optischen Fasern bestehen als auch über einen Freistrahlansatz mittels mehrerer Spiegel realisiert werden. Somit kann die Übertragung von Laserstrahlung aufgrund der Fasereigenschaften räumlich flexibel und kompakt gestaltet werden bzw. zwischen zwei Spiegeln weitere für die Anwendung essentielle Optiken in den Strahlengang implementiert werden. Eine typische moderne Anwendung bestehend aus zwei Spiegeln ist die positionsgenaue Bestrahlung einer Fläche mittels eines Galvanometer-Scanners. Unabhängig von der Anwendung müssen optische Komponenten eine möglichst lange und sichere Betriebsdauer gewährleisten, um einen ungeplanten Prozessausfall zu verhindern und den einhergehenden Kosten- und Zeitaufwand zu reduzieren. Diesbezüglich ist die Laser-induzierte Zerstörschwelle (LIDT) die wichtigste Kenngröße zur Charakterisierung einer optischen Komponente, um eine dauerhafte Prozesstauglichkeit bei gegebenen Laserparametern abzuschätzen. Entsprechend wurden in der Vergangenheit zur Vereinheitlichung der Messroutine und des Vergleichs zwischen mehreren Institutionen geeignete Normen erarbeitet. Die rapide Entwicklung leistungsstärkerer Lasersysteme, kompakter werdende optische Systeme, steigende Komponentenqualität sowie die Anwendung alternativer Materialien führen jedoch zu Abweichungen im Zerstörverhalten und den Auswirkungen einzelner Zerstörungen, auf denen die Messprinzipien aufgebaut wurden. Aus diesen Gründen werden in dieser Arbeit geeignete Messroutinen zur Bestimmung der LIDT präsentiert, welche insbesondere den speziellen Zerstörcharakteristiken moderner optischer Komponenten gerecht werden. Die Studien sind auf die Nanosekunden-gepulste Bestrahlung von polymeren optischen Fasern sowie die Laser-induzierte Zerstörung von optischen Spiegeln mittels Laserstrahlung mit Ausgangsleistungen im Kilowattbereich fokussiert. Diese Komponenten sind wegen ihres Zerstörverhaltens von besonderem Interesse. Die Zerstörung von Polymeren findet im Nanosekunden-gepulsten sichtbaren Bereich typischerweise im Volumen statt und führt bei optischen Fasern zur Berücksichtigung der komplexen und stetig variierenden Intensitätsverteilung während der Propagation. Im Gegensatz dazu ist die Zerstörung im Dauerstrichbereich auf thermische Phänomene zurückzuführen. Jedoch basieren die Näherungen zur Beschreibung des Zerstörverhaltens auf große optische Komponenten und einem vergleichsweise kleinem Strahldurchmesser, weswegen die Approximationen nur begrenzt auf die heutzutage relativ kleinen Spiegel anzuwenden sind. Die Resultate bezüglich dieser genannten wissenschaftlichen Herausforderungen und die Erarbeitung verlässlicher Messroutinen sind in der vorliegenden Arbeit detailliert dargestellt. Eine verlässliche Bestimmung der LIDT mittels der angepassten Messroutinen und entsprechender Evaluation der Daten wurde im Rahmen dieser Arbeit für die beiden Probenarten demonstriert. Das Zerstörverhalten der polymeren optischen Fasern in Abhängigkeit der komplexen Intensitätsverteilung während der Propagation innerhalb der Faser konnte nachgewiesen werden, und die Ursache wird auf aus der Literatur bekannte Zerstörmechanismen polymerer Materialien zurückgeführt. Die Untersuchungen von Spiegeln mittels kontinuierlicher Laserstrahlung zeigten einen grundlegend thermischen Mechanismus. Aufgrund der hohen Qualität der Komponenten wird die rein intrinsische Zerstörung in Einzelfällen von der erhöhten Absorption von Fehlstellen dominiert. In praxisnahen Messungen mittels eines Galvanometer-Scanner konnten unter den kritischsten Bedingungen lokale thermische Materialänderungen, welche den Prozess nicht einschränkten, nachgewiesen werden.Modern optical laser beam guidance systems are necessary for many laser applications. These systems can consist of optical fibers as well as free space approaches using mirrors. Thus the transfer of the laser beam can be realised spatially flexible utilizing waveguide properties or rather quickly adaptable allowing other optical components to be implemented in the beam path. A typical application is for instance a galvo scanner consisting of two mirrors allowing the precise irradiation of the area of interest. Optical components need to guarentee a safe and long-lasting operating time independent of the usage to prevent unscheduled process failure reducing accompanying cost and time expenses. With regards to this, the laser-induced damage threshold (LIDT) is one of the most important physical quantities to characterize the long-term process suitability of an optical component for given laser parameters. Consequently, detailed standards were developed in the past to create a unified measurement routine allowing a straight-forward comparison between multiple institutes. However, laser systems with increasing output power are developed each year, the optical systems are getting more compact, the components quality rises and different as well as novel materials are used. This leads to deviations in the damage behavior and the impact of single laser-induced damage sites on the components properties on which the measurement routines are based on. For these reasons, this work presents suitable measurementroutines to determine the LIDT of modern optical components which have relatively specific damage characteristics. The investigations are focused on the nanosecond pulse induced damages in polymer optical fibers, as well as the thermal-driven damage mechanism of optical mirrors by continuous wave lasers with powers of several kilowatts. These components are of high interest due to their damage behavior. Damages usually occur in polymer materials in the nanosecond pulse visible range in the bulk material which requires the consideration of the complex varying intensity distriution during the propagation within the fiber. In contrast, the damage behavior of mirrors in the continuous wave regime is governed by thermal mechanisms but previous approv ximations are not suitable regarding todays small optical components. The results regarding these scientific challenges and the development of suitable measurement routines are presented in detail in this work. A reliable determination of the LIDT using an adapted measurement procedure and a corresponding evaluation of the data was demonstrated in the studies for two beam guiding components. The damage behavior of polymer optical fibers in dependence of the complex intensity distribution along the fiber was observed, and the cause is led back to damage mechanisms reported in the literature. The investigations of mirrors under continuous wave laser irradiation show a fundamentally thermal mechanism. Due to the high quality of the mirrors the pure instrinsic damage behavior is dominated in some cases by the absorption of defects. Application-driven studies using a galvo scanner under its most critical conditions proofed the generation of locally thermal-driven material modifications, which however did not limit the process

Restoring Ukraine: Parallels Between Visegrad Group and East Germany in the 90s

Ukraine's post-conflict economy needs new opportunities to grow because it has not been able to rebuild itself economically. As we live in an era of globalization, it is crucial that national economies - especially Ukraine's - meet the demands of the international community. With its advantageous geo-economic position between the East and the West, its geographic centre within Europe, and its abundance of natural resources, Ukraine has every opportunity to become a truly vital component of the global economy. These days, the subject of Ukraine comes up frequently in conversations with a wide variety of people. Unfortunately, there isn’t a consensus on a single strategy for solving the goal-setting conundrum and a precise algorithm for achieving that goal. To date, there isn’t the single national recovery plan with legal status that other recovery actors can use as a tactical weapon. To develop a model of Ukraine's post-war economic recovery, to define the country's recovery goal, and to provide an answer to the question of how to get there, in this essay I have tried to examine the experience of other countries that have recovered economically from crises. The focus is on the study of the Visegrad Group and East Germany during the 1990s. I have attempted to organize the major influences and theories that might be relevant to the study of Ukraine's restoration.Die Post-Konflikt-Wirtschaft der Ukraine braucht neue Wachstumschancen, da es ihr nicht gelungen ist, sich wirtschaftlich wieder aufzubauen. Im Zeitalter der Globalisierung ist es von entscheidender Bedeutung, dass die Volkswirtschaften, insbesondere die der Ukraine, den Anforderungen der internationalen Gemeinschaft gerecht werden. Mit ihrer vorteilhaften geoökonomischen Lage zwischen Ost und West, ihrem geografischen Zentrum in Europa und ihrem Reichtum an natürlichen Ressourcen hat die Ukraine alle Chancen, ein wirklich wichtiger Teil der Weltwirtschaft zu werden. Das Thema Ukraine kommt heute in Gesprächen mit den unterschiedlichsten Menschen immer wieder zur Sprache. Leider gibt es keinen Konsens über eine einheitliche Strategie zur Lösung des Zielproblems und über einen genauen Algorithmus zur Erreichung dieses Ziels. Bisher gibt es keinen einzigen nationalen Sanierungsplan mit Rechtsstatus, den andere Sanierungsakteure als taktische Waffe einsetzen könnten. Um ein Modell für die wirtschaftliche Erholung der Ukraine nach dem Krieg zu entwickeln, das Erholungsziel des Landes zu definieren und eine Antwort auf die Frage zu geben, wie man dorthin gelangt, habe ich in diesem Aufsatz versucht, die Erfahrungen anderer Länder zu untersuchen, die sich wirtschaftlich von Krisen erholt haben. Der Schwerpunkt liegt auf der Untersuchung der Visegrád-Gruppe und Ostdeutschlands in den 1990er Jahren. Ich habe versucht, die wichtigsten Einflüsse und Theorien zu ordnen, die für die Untersuchung der Erholung der Ukraine relevant sein könnten

Smartphone Based Detection of Vehicle Encounters

Riding a bicycle in shared traffic alongside motor vehicles causes discomfort or even stress for many cyclists. Avoiding busy or crowded roads is only possible with good local knowledge, as no data is available on the frequency of encounters with motor vehicles for most roads. Acquiring a data set that combines smartphone sensor data with known vehicle encounters can become the foundation for a smartphone based moving vehicle detector. Therefore, readings from the omnipresent smartphone sensors magnetometer and barometer can be exploited as indicators of passing vehicles. In this paper, a novel approach is presented to detect vehicle encounters in smartphone sensor data. For this purpose, a modular mobile sensor platform is first constructed and set up to collect smartphone, camera and ultrasonic sensor data in real traffic scenarios. The platform is designed to be used with various sensor configurations to serve a broader set of use cases in the future. In the presented use case, the platform is constructed to create a reference data set of vehicle encounters consisting of location information, direction, distance, speed and further metadata. To this end, a methodology is presented to process the collected camera images and ultrasonic distance data. Furthermore, two smartphones are used to collect raw data from their magnetometer and barometric sensor. Based on both, the reference and the smartphones’ data set, a classifier for the detection of vehicle encounters is then trained to operate on pure smartphone sensor data. Experiments on real data show that a Random Forest classifier can be successfully applied to recorded smartphone sensor data. The results prove that the presented approach is able to detect overtaking vehicle encounters with a F1-score of 71.0 %, which is sufficient to rank different cycling routes by their ’stress factor’

Towards a Resolution of Ethnic Comparative Research with Minority and Majority Adolescents

Developmental contexts are becoming increasingly culturally diverse. Because of changing minority-majority dynamics and an increased awareness of inequities rooted in racially stratified societies, the study of developmental processes in different ethnic groups of adolescents has become a challenge. How can research shift the focus from describing to explaining group differences based on psychological and social mechanisms? How can researchers accurately investigate differences and similarities between groups without running the risk of perpetuating a deficit-oriented perspective? An ethnic comparative perspective, although often criticised (e.g., promotes power imbalance between ethnic groups, encourages ‘otherness’), can complement other research methods to explain immigrant youth’s adjustment in different contexts, identify structural barriers to a positive adaptation and, determine underlying variables (e.g., socioeconomic status, opportunity differentials) that create differences that may otherwise be attributed to culture. This dissertation focuses on comparative approaches with ethnic minority and majority youth and shows how these can be utilised to understand developmental processes in various ethnic groups. I present three alternative ways to do this, together with empirical evidence based on cultural variance between minority (i.e., adolescents themselves or at least one parent born outside Germany; shared experience of belonging to a minority group) and majority (i.e., no migration history in their own or their parents’ generation; shared experience of belonging to a majority group) groups. In the first study, I ‘explain away’ minority–majority differences in developmental trajectories of life satisfaction and academic self-efficacy. This approach is performed with the particular research question of how specific features of the home learning environment (e.g., learning conditions at home and parental involvement) can improve psychological and school adjustment. It also shows that student–teacher communication and family support are important factors that can improve home learning in both groups. As explaining away ethnic disparities may not always be possible, in the second study I compare minority and majority student–teacher dyads by drawing on multicultural education theory and add group–specific predictors. I investigate how students and their classroom teachers perceive the teacher–student relationship quality and which predictors at the student-level and classroom-level explain differences in students’ and teachers’ perceptions. The third study adopts a person-oriented approach, as an opportunity to study youth from different ethnic groups (i.e., ethnic German diaspora adolescents who migrated from the former Soviet Union to Germany, Russian Jews who migrated from the former Soviet Union to Israel, and majority adolescents in Germany) without an ethnic comparative mindset. This study uncovers subgroups of adolescents based on their perceived social support trajectories and identifies developmental and acculturation-related variables as predictors of subgroup membership. I conclude with a debate on the ethnic comparative approach, as well as other approaches (e.g., intersectional research) that may ensure a more comprehensive picture of youth adjustment in highly diverse contexts