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Laser-induced tuning of crystallization in tetracene thin films
No full textThis study explores how laser light affects the morphology of tetracene films, and it presents novel strategies for improving the creation of thin films used in (opto-)electronic devices. We demonstrate that laser light (532 nm, 1.1 W mm −2 ), applied during tetracene deposition, not only increases grain size but also induces photoalignment. The observed effects arise from enhanced molecular diffusion, resulting from energy transferred by light to the molecules after adsorption, but not from heating the substrate surface underneath. We observe that linearly polarized light promotes photoalignment, while increased crystallite sizes occurs with both linear and circular polarizations. We propose an Ostwald ripening process facilitated by laser illumination, where smaller crystallites get optically heated and dissolve, allowing molecules to surmount step-edge barriers and assemble into larger crystallites. Importantly, the crystallite sizes achieved with laser illumination surpass those attainable by substrate heating alone. The study demonstrates that laser illumination acts as a promising new parameter for controlling thin film properties and is distinct from growth control via substrate temperature and growth rate. Light control also includes the ability for lateral patterning, with implications for the future of molecular materials and their manufacturing technologies.Deutsche Forschungsgemeinschaft 10.13039/501100001659German Academic Exchange Service 10.13039/100021828Peer Reviewe
Macrovibrissae and microvibrissae inversion and lateralization in elephants
No full textElephants are known for strongly lateralized trunk behaviors, but the mechanisms driving elephant lateralization are poorly understood. Here, we investigate features of elephant mouth organization that presumably promote lateralization. We find the lower jaw of elephants is of narrow width, but is rostrally strongly elongated even beyond the jaw bone. Elephant lip vibrissae become progressively longer rostrally. Thus, elephants have two lateral dense, short microvibrissae arrays and central, less dense long macrovibrissae. This is an inversion of the ancestral mammalian facial vibrissae pattern, where central, dense short microvibrissae are flanked by two lateral macrovibrissae arrays. Elephant microvibrissae have smaller follicles than macrovibrissae. Similar to trunk‐tip vibrissae, elephant lip microvibrissae show laterally asymmetric abrasion. Observations on Asian zoo elephants indicate lateralized abrasion results from lateralized feeding. It appears that the ancestral mammalian mouth (upper and lower lips, incisors, frontal microvibrissae) is shaped by oral food apprehension. The elephant mouth organization radically changed, however, because trunk‐mediated feeding replaced oral apprehension. Such elephant mouth changes include the upper lip–nose fusion to the trunk, the super‐flexible elongated lower jaw, the loss of incisors, and lateral rather than frontal microvibrissae. Elephants’ specialization for lateral food insertion is reflected by the reduction in the centering effects of oral food apprehension and lip vibrissae patterns.ERC BrainPlayDFG NeuroCure–EXC‐2049Peer Reviewe
Retrodigitalisierung der Privatbibliothek des Turnpädagogen H. O. Kluge
No full textDie Gelehrtenbibliothek des Turnpädagogen Hermann Otto Kluge (1818-1882) ist ein Teilbestand des historischen sportwissenschaftlichen Bestands, der in der Zweigbibliothek Campus Nord der Universitätsbibliothek (UB) der Humboldt-Universität zu Berlin aufbewahrt wird. Sie gehört insgesamt zu den vor Ort und über die Fernleihe am meisten genutzten Altbeständen dieses Standorts
Functional investigation of the regulatory landscape around the Xist locus
No full textRegulatorische Landschaften von Genen steuern das präzise transkriptionelle Programm, das für die embryonale Entwicklung notwendig ist. Transkriptionsfaktoren (TFs) interagieren dabei mit regulatorischen Elementen (REs), um die Genexpression zu kontrollieren. Zur Untersuchung der zugrundeliegenden Mechanismen konzentriere ich mich auf das Xist-Gen, den Hauptregulator der X-Chromosom-Inaktivierung (XCI) in Säugetieren. In der Embryonalentwicklung wird Xist monoallelisch in weiblichen Zellen aktiviert, woraufhin die Xist-RNA das X-Chromosom überzieht und dessen Inaktivierung einleitet. Dadurch wird die erhöhte Dosis X-chromosomaler Gene in weiblichen Zellen kompensiert. Um ein umfassendes Verständnis der Xist-Regulatoren zu erhalten, nutze ich CRISPR-Screens, um REs und TFs in weiblichen embryonalen Stammzellen zu untersuchen. Dabei identifiziere ich ein neues nicht-kodierendes Gen namens Xert. Daruberhinaus stelle ich fest, dass promotor-nahe REs auf die Anzahl der X-Chromosomen reagieren, während distale REs unbeeinflusst bleiben. Durch meine TF-Screens entdecke ich zwei Gruppen von Aktivatoren: Die frühe Gruppe, darunter der X-chromosomale Faktor ZIC3, zeigt in weiblichen Zellen erhöhte Expression, was darauf hindeutet, dass sie die Xist-Expression auf weibliche Zellen beschränken. Die späte Gruppe, einschließlich OTX2, agiert geschlechtsunabhängig und stellt nach der initialen Xist-Aktivierung ein hohes Transkriptionslevel sicher. Mit weiteren CRISPR-Screens verknüpfe ich TFs mit REs und zeige, dass frühe Aktivatoren promotor-nahe REs beeinflussen, während späte Aktivatoren distale REs stärker regulieren. Diese Arbeit liefert eine systemische Perspektive des trans- und cis-regulatorischen Netzwerks, das die Xist-Aktivierung während der Differenzierung koordiniert und die Beschränkung auf weibliche Zellen gewährleistet.The regulatory landscapes of developmental genes orchestrate precise and coordinated transcriptional programs required for embryonic development. During this process, transcription factors (TFs) interact with regulatory elements (RE) to finely tune gene expression. To study the regulatory principles acting in this context, I focus on the Xist gene, the master regulator of X-chromosome inactivation (XCI) in mammals. During early development, Xist is upregulated in a monoallelic fashion specifically in females. The Xist RNA then coats the X chromosome in cis, resulting in its inactivation. In this manner, female cells compensate for their increased X-chromosomal dosage in comparison to males. To obtain a complete understanding of Xist regulation, I first perform two CRISPR screens targeting REs and TFs during the early differentiation of female mouse embryonic stem cells. I identify Xist-controlling REs within the locus, unveiling a novel non-coding gene Xert. I further demonstrate the sensitivity of promoter-proximal REs to X-dosage, contrasted by the behavior of distal REs. In the TF screen, I detect two sets of activators which undergo transient upregulation at the onset of XCI. The early group of activators, including the X-linked TF ZIC3, exhibits higher expression levels in XX cells, indicating a role in restricting Xist expression to females. The late group of activators, including the master regulator of the epiblast OTX2, drives high transcript levels following Xist activation. Subsequently, I use a series of CRISPR screens targeting individual reporter constructs to map TF-RE wiring at the locus. I find that the early activators primarily act on the XX-dependent proximal REs. Contrary, the late activators interact with the sex-independent distal REs. With this study, I provide a systems level perspective of the trans- and cis-regulatory network that links Xist activation to early differentiation and ensures female-specificity
The Religious Leaders’ Perspectives on Corona Survey: Methods and Key Results
No full textReligious leaders are highly influential actors in many societies across the globe. In the singular global crisis brought upon by the COVID-19 pandemic, their perspective on the pandemic itself but also the post-pandemic future is of high relevance. Against this background, we conducted the Religious Leaders’ Perspectives on Corona Survey, a comprehensive survey of 1200 religious leaders globally, in 2020/2021. Its aim was to investigate the role of religious communities and religious leaders during the COVID-19 pandemic. This article provides an in-depth outline and discussion of the survey methodology and the resultant dataset, thereby paving the way for future research using the survey data. Moreover, the first set of key results is highlighted. It emerges that the COVID-19 pandemic was not primarily a health crisis. Rather, in terms of its consequences, COVID-19 had the characteristics of a primarily economic crisis in the Global South and a primarily psychosocial crisis in the Global North. Moreover, the pandemic has had a fundamental impact on religious practice across the globe. This impact, however, seems to be highly unequal between the Global South and North. Religious communities are shown to have had an important role as civil society actors in the pandemic, providing both psychosocial and material support. Regarding the post-pandemic world, religious leaders envision a more equitable society and emphasize the need for environmental sustainability.Financial support by the German Federal Ministry of Economic Cooperation and Development for the research project “Driving Forces of Transformation: Religious Communities as Agents of Sustainable Development” is gratefully acknowledged. Moreover, Philipp Öhlmann acknowledges financial support from the Alexander von Humboldt Foundation through a Feodor Lynen Research Fellowship.Alexander von Humboldt FoundationGerman Federal Ministry of Economic Cooperation and DevelopmentPeer Reviewe
Exploring (Anti-)Radicalism on TikTok: German Islamic Content Creators between Advocacy and Activism
No full textThe article processing charge was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 491192747 and the Open Access Publication Fund of Humboldt-Universität zu Berlin.This study explores the representation of radical and anti-radical ideologies among German Islamic TikTok creators, analyzing 2983 videos from 43 accounts through qualitative content analysis. The results reveal two main content clusters: religious practice involving social/lifestyle issues and political activism around Muslim grievances. Victimization, found in 150 videos, was the most common indicator associated with radicalization and emerged as a source of political activism and subversive discourse. Overall, indicators of radicalism were scarce, suggesting that visible mainstream Islamic creators do not exhibit high levels of radical ideology. However, this also reflects a selection bias in the design of this study, which systematically overlooks fringe actors. In addition, religious advocacy was the most common topic (1144 videos), serving as a source of guidance and motivation, but was occasionally linked to sectarianism and rigid religious interpretations. Male creators posted more religious/theological videos; female creators posted more lifestyle videos. However, gender distinctions are limited due to the low representation of female creators (6). Some topics, such as the hijab, served as an intersection between religious practice and politicized narratives. This study highlights TikTok’s role in promoting diverse ideological views and shaping community engagement, knowledge sharing, and political mobilization within Germany’s Muslim digital landscape.This research was funded by the German Ministry for Education and Research (Project ID 01UG2035, “German Islam”). The article processing charge was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—491192747 and the Open Access Publication Fund of Humboldt-Universität zu Berlin. This work was supported by the University of Mannheim’s Graduate School of Economic and Social Sciences and received additional funding through its Young Scholar Award.German Ministry for Education and ResearchDeutsche Forschungsgemeinschaft (DFG, German Research Foundation)the Open Access Publication Fund of Humboldt-Universität zu BerlinUniversity of Mannheim’s Graduate School of Economic and Social SciencesPeer Reviewe
Hybrid Methods for the Analysis and Synthesis of Human Faces
No full textDer Trend hin zu virtueller Realität (VR) hat neues Interesse an Themen wie der Modellierung menschlicher Körper geweckt, da sich neue Möglichkeiten für Unterhaltung, Konferenzsysteme und immersive Anwendungen bieten.
Diese Dissertation stellt deshalb neue Ansätze für die Erstellung animierbarer/realistischer 3D-Kopfmodelle, zur computergestützten Gesichtsanimation aus Text/Sprache sowie zum fotorealistischen Echtzeit-Rendering vor.
Um die 3D-Erfassung zu vereinfachen, wird ein hybrider Ansatz genutzt, der statistische Kopfmodelle mit dynamischen Texturen kombiniert.
Das Modell erfasst Kopfhaltung und großflächige Deformationen, während die Texturen feine Details und komplexe Bewegungen kodieren.
Anhand der erfassten Daten wird ein generatives Modell trainiert, das realistische Gesichtsausdrücke aus einem latenten Merkmalsvektor rekonstruiert.
Zudem wird eine neue neuronale Rendering-Technik presentiert, die lernt den Vordergrund (Kopf) vom Hintergrund zu trennen.
Das erhöht die Flexibilität während der Inferenz (z. B. neuer Hintergrund) und vereinfacht den Trainingsprozess, da die Segmentierung nicht vorab berechnet werden muss.
Ein neuer Animationsansatz ermöglicht die automatische Synthese von Gesichtsvideos auf der Grundlage weniger Trainingssequenzen.
Im Gegensatz zu bestehenden Arbeiten lernt das Verfahren einen latenten Merkmalsraum, der sowohl Emotionen als auch visuelle Variationen der Sprache erfasst, während gelernte Priors Animations-Artefakte und unrealistische Kopfbewegungen minimieren.
Nach dem Training ist es möglich, realistische Sprachsequenzen zu erzeugen, während der latente Stil-Raum zusätzliche Gestaltungsmöglichkeiten bietet.
Die vorgestellten Methoden bilden ein Komplettsystem für die realistische 3D-Modellierung, Animation und Darstellung von menschlichen Köpfen, das den Stand der Technik übertrifft. Dies wird in verschiedenen Experimenten, Ablations-/Nutzerstudien gezeigt und ausführlich diskutiert.The recent trend of virtual reality (VR) has sparked new interest in human body modeling by offering new possibilities for entertainment, conferencing, and immersive applications (e.g., intelligent virtual assistants). Therefore, this dissertation presents new approaches to creating animatable and realistic 3D head models, animating human faces from text/speech, and the photo-realistic rendering of head models in real-time.
To simplify complex 3D face reconstruction, a hybrid approach is introduced that combines a lightweight statistical head model for 3D geometry with dynamic textures. The model captures head orientation and large-scale deformations, while textures encode fine details and complex motions. A deep variational autoencoder trained on these textured meshes learns to synthesize realistic facial expressions from a compact vector. Additionally, a new neural-rendering technique is proposed that separates the head (foreground) from the background, providing more flexibility during inference (e.g., rendering on novel backgrounds) and simplifying the training process as no segmentation masks have to be pre-computed.
This dissertation also presents a new neural-network-based approach to synthesizing novel face animations based on emotional speech videos of an actor. Unlike existing works, the proposed model learns a latent animation style space that captures emotions as well as natural variations in visual speech. Additionally, learned animation priors minimize animation artifacts and unrealistic head movements. After training, the animation model offers temporally consistent editing of the animation style according to the users’ needs.
Together, the presented methods provide an end-to-end system for realistic 3D modeling, animation, and rendering of human heads. Various experimental results, ablation studies, and user evaluations demonstrate that the proposed approaches outperform the state-of-the-art
Foundations for a national assessment of soil biodiversity
No full textSoils, just like all other ecosystem compartments, change over time and, consequently, conditions for soil-inhabiting organisms are also changing, affecting their composition and diversity. Soil biodiversity is a critical component of ecosystems that supports many essential ecosystem functions and services, such as nutrient cycling, carbon sequestration, water regulation and biomass production for food, fodder, fibre and energy. However, and despite the importance of soil biodiversity for ecosystem health and human well-being, neither current state, drivers, potential consequences for ecosystem services nor options for sustainable governance of soil biodiversity are well understood. Here, we provide a framework for and argue that conducting a national assessment of soil biodiversity, albeit being a complex endeavour, is fundamental to building a baseline to understand the current state and trends of soil biodiversity, but also to identify the main drivers of change, the impacts of soil biodiversity loss and the potential pathways for conservation and sustainable governance of soil biodiversity.Fundação para a Ciência e a TecnologiaPeer Reviewe
Reintroduced, but not accepted: Stakeholder perceptions of beavers in Germany
No full text1. While reintroductions of regionally extinct native species usually benefit ecosystems, reintroduced animals often struggle to locate appropriate habitats where they can establish themselves without conflict with humans. European beavers (Castor fiber) were successfully reintroduced to Germany almost 60 years ago and have reached high abundances again. As beavers can damage trees and change landscapes, they are increasingly in conflict with humans.
2. We investigated human perceptions of beavers in Germany using an online survey, as they are an example of a reintroduced species with an expanding population and potential conflicts with humans. We asked participants about their emotions (anger, fear, interest, joy) towards beavers and what they consider to be acceptable beaver habitats.
3. Of nearly 1500 survey participants, 803 (53%) were from the general public, 475 (32%) from the agricultural sector and 219 (15%) from forestry. People in these sectors had very different perspectives: beavers were positively perceived by the general public, but negatively by stakeholders working in agriculture and forestry. Independently of stakeholder groups, we also found regional differences, as participants from Bavaria—the German state with the highest beaver densities—viewed beavers more negatively than those from the rest of Germany.
4. Zoos and wildlife parks, as well as urban and nature conservation areas, were considered to be the most acceptable habitats for beavers, whereas survey participants did not accept private gardens and cultivated areas as beaver habitats.
5. We discuss the sources of negative emotions towards beavers and how ecologically suitable habitats differ from those that appear acceptable by humans. Even 60 years after their reintroduction, beavers in Germany are still being recognized as both a novelty and a nuisance. Our findings highlight the need for active beaver management and increased public engagement to enable positive coexistence between beavers and humans in Germany.Deutsche Bundesstiftung Umwelt http://dx.doi.org/10.13039/100007636Peer Reviewe
