31325 research outputs found
Sort by
Biology and Diversity of the Earliest Herbivores
No full textHerbivoren erfüllen eine zentrale Rolle in Ökosystemen. Daher stellt der Ursprung der Tetrapoden-Herbivorie ein Schüsselereignis für die Entwicklung moderner terrestrischer Ökosysteme dar. Obwohl terrestrische Pflanzen als Tetrapoden bereits im Mitteldevon koexistierten, entwickelten die Tetrapoden keine Skelettanpassungen für Herbivorie bis in das späte Karbon hinein, 70 Ma später. Diese Anpassungen fielen offenbar mit der Radiation der Amnioten zusammen, wohingegen keine herbivore Amphibien bekannt sind. Diese Beobachtungen weisen darauf hin, dass Schlüsselmerkmale ihren Ursprung nahe der Basis der Amniota haben. Diese Dissertation legt aus den Bereichen der Kieferosteologie und Biomechanik von paläozoischen Tetrapoden und Schildkröten Hinweise für diese Hypothese vor. Kapitel 1 und 2 sind in wissenschaftlichen Zeitschriften erschienen; Kapitel 3 ist als unveröffentlichtes Manuskript angefügt. Ich befasse mich mit der phylogenetischen Position der Diadectomorpha, die die frühesten herbivoren Tetrapoden enthält, indem wir die Osteologie von vier dazugehörigen Spezies mit 3D-Scans aktualisieren. Im Majority-Rule Consensus werden Diadectomorpha als Amnioten klassifiziert. Der zweite Teil der Dissertationsschrift schaut die Biomechanik von Kiefern an. Herbivore Schildkröten erreichen höhere Kraftübertragung als ihre nicht-herbivoren Verwandten. In Kapitel 3 messe ich Kiefer-Biomechanik und -Formdisparität von Tetrapoden des Permokarbons. Amniotenkiefer zeigen größere Disparität als die Kiefer von Nicht-Amnioten. Ab dem frühen Perm übertrifft die relative Disparität von Amnioten die von Nicht-Amnioten. Amnioten haben höhere Kiefer, längere Symphysen und höheren mechanischen Vorteil entwickelt als andere Tetrapoden. Ich diskutiere die Verschiebung des primären Atmungsmechanismus von Amnioten als ein mögliches Schlüsselmerkmal, dass durch das Auflösen von Beschränkungen der Schädelmorphologie die Entwicklung von Skelettanpassungen an die Herbivorie ermöglichte.Herbivores fulfil a key role in modern terrestrial ecosystems. The origin of herbivory in tetrapods thus marked a crucial event in the development of modern terrestrial ecosystems. Although terrestrial plants and tetrapods co-existed since the Middle Devonian, tetrapods did not develop skeletal adaptations for herbivory until the Late Carboniferous; a delay of 70 Ma. These adaptations notably coincided with the diversification of amniotes, whereas no herbivorous lissamphibians are known. These observations suggest a key trait allowing tetrapods to develop herbivory evolved near the base of Amniota. This thesis presents further evidence supporting this hypothesis using mandibular osteology, biomechanics and disparity in Palaeozoic tetrapods and turtles as modern analogue. The first two chapters are published in peer-reviewed journals; Chapter 3 is added as unsubmitted manuscript. I reassess the phylogenetic position of Diadectomorpha, the clade that includes the earliest herbivorous tetrapods, updating the mandibular osteology of four diadectomorph species using μCT-scans. The majority-rule consensus recovers diadectomorphs as amniotes. The second part of the thesis reviews jaw biomechanics and disparity. Like other tetrapod groups, herbivorous turtles achieve greater force transmission than non-herbivorous relatives. Amniote jaws are more disparate than the jaws of non-amniote tetrapods in the Palaeozoic. Relative disparity of amniotes exceeds that of other tetrapods from the early Permian. Amniotes develop deeper jaws and a longer symphysis, and a higher mechanical advantage than other tetrapods. I discuss a shift in primary mode of breathing in amniotes which relieves constraints on skull morphology, as potentially the key trait allowing for the development of skeletal adaptations to herbivory. This would explain the apparent delay in the evolution of tetrapod herbivory and its coincidence with the rise of amniotes
Towards a typology of unitization: noun classes, classifiers, singulatives
No full textLanguages often employ morphosyntactic strategies to "unitize" mass and collective nouns in contexts where reference to individual units is intended, such as English /one pound of flour/ or /one head of cattle/. This chapter explores cross-linguistic variation in grammatical unitization strategies, drawing on a comparison of an Amazonian noun class system with singulative markers and numeral classifiers. While the descriptive facts on these systems have been known for some time, their integration into a unified framework provides new perspective on the interplay between classification, countability, and number marking. This chapter proposes eight parameters for a typology of unitization, capturing properties of the nouns to which unitization applies, of the unitizing elements involved, of the grammatical locus of these elements, and of their interaction with number marking
Retinal to Retinal Energy Transfer in a Bistable Microbial Rhodopsin Dimer
No full textNeorhodopsin (NeoR) is a newly discovered fungal bistable rhodopsin that reversibly photoswitches between UV- and near-IR absorbing states denoted NeoR367 and NeoR690, respectively. NeoR367 represents a deprotonated retinal Schiff base (RSB), while NeoR690 represents a protonated RSB. Cryo-EM studies indicate that NeoR forms homodimers with 29 Å center-to-center distance between the retinal chromophores. UV excitation of NeoR367 takes place to an optically allowed S3 state of 1Bu+ symmetry, which rapidly converts to a low-lying optically forbidden S1 state of 2Ag– symmetry in 39 fs, followed by a multiexponential decay to the ground state on the 1–100 ps time scale. A theoretically predicted nπ* (S2) state does not get populated in any appreciable transient concentration during the excited-state relaxation cascade. We observe an intradimer retinal to retinal excitation energy transfer (EET) process from the NeoR367 S1 state to NeoR690, in competition with photoproduct formation. To quantitatively assess the EET mechanism and rate, we experimentally addressed and modeled the EET process under varying NeoR367-NeoR690 photoequilibrium conditions and determined the EET rate at (200 ps)−1. The NeoR367 S1 state shows a weak stimulated emission band in the near-IR around 700 nm, which may result from mixing with an intramolecular charge-transfer (ICT) state, enhancing the transition dipole moment of the S1–S0 transition and possibly facilitating the EET process. We suggest that EET may bear general relevance to the function of bistable multiwavelength rhodopsin oligomers.Peer Reviewe
Migration context of emergency department patients and patterns of their in- and outpatient healthcare utilization – analysis of three INDEED study centers in Berlin
No full textBackground: Increasing sociocultural diversity has implications for emergency department (ED) care. Individuals with a migration context face challenges that can manifest as barriers in healthcare access and use. Therefore, our aim was to examine differences in healthcare delivery for and utilization of ED patients in Germany regarding their migration context. Methods: We utilized routine healthcare data from the INDEED project. Patient records from three EDs in Berlin, Germany, from 2016 were linked with associated outpatient treatment data spanning 2014 to 2017. Using an onomastic approach, patients were assigned to one of nine regions of origin (refers to “migration context”) based on their names in addition to citizenship. Demographic and clinical data were compared between patients with and without a presumed migration context. Regression analyses were conducted to determine the association of migration context on triage category, hospital admission, frequent ED use (more than two visits within one year), and the number of outpatient presentations, adjusting for sex, age in years and multimorbidity (more than three different diagnoses over three calendar quarters within four consecutive calendar quarters before the first ED visit). Results: In total, 123 572 (49 003 (40.2%), 74 569 (59.8%) without presumed migration context) cases were examined. ED patients with a presumed migration context were younger and more often male than those without. Adjusted regression analyses demonstrated that the overall migration context was associated with a slightly higher likelihood of more urgent triage categorization (adjusted odds ratio: 1.03; 95%-confidence interval: 1.01–1.04), while it was also associated with fewer hospital admissions after the ED stay (adjusted odds ratio 0.92; 95%-confidence interval 0.90–0.96), being a frequent ED user (1.22; 1.15–1.30), and fewer contacts with outpatient healthcare services (exponentiated estimates 0.86; 0.85–0.86). Conclusion: Our routine data analysis highlighted differences in healthcare pathways between ED patients with and without a presumed migration context in Germany. The likely complex and multifactorial reasons behind these disparities warrant further investigation, preferably by prospective studies. Understanding these factors can enhance the promotion of healthcare provision that is more sensitive to a diverse society.Open Access funding enabled and organized by Projekt DEAL.Charité - Universitätsmedizin Berlin (3093)Peer Reviewe
Tropical dry woodland loss in India since 1880 and its relation to current megafauna distributions
No full textTropical dry woodlands provide ecosystem services to hundreds of millions of people and support high biodiversity. Despite their importance, many dry woodlands are under high and rising human pressure, including in India, where they provide essential habitat for iconic megafauna. However, there are notable gaps in our understanding of long‐term changes in dry woodlands and how they relate to the present‐day distribution of megafauna. Here, we reconstructed tropical dry woodland change since the 19th century, identified archetypes of change, and explored their relationship with current megafauna distributions. More specifically, we compared the reliability of existing satellite‐based woodland maps and integrated them into an ensemble map of contemporary dry woodland cover in India. This allowed us to derive recent changes in dry woodlands since 1995 and, by integrating them with historical maps, long‐term changes since 1880. Finally, we used non‐parametric spatial clustering to detect typical patterns of long‐term woodland change and compared these to the current distribution of 14 megafauna species. These analyses yielded four major insights. First, we show a massive historical loss of dry woodland cover in India since the 19th century, with over 22 Mha (equaling 65% of dry woodlands) lost, underscoring the threatened nature of these ecosystems. Second, we identified six archetypes of woodland change, three characterized by different levels of continuous woodland decline and three showing a forest transition pattern of historical decline, stability, and subsequent recovery. This highlights the regional variations in woodland dynamics across India's dry woodlands. Third, we found a strong and positive link between current megafauna distribution and high woodland cover, especially for threatened species ( r = 0.43, p < 0.05), regardless of woodland histories, pointing to the importance of maintaining larger tracts of dry woodlands for safeguarding megafauna and for megafauna restoration potential where woodlands are recovering. Finally, we show that Indian dry woodlands are still undergoing widespread losses of 6.5 Mha since 1995, and pressure on them has been increasing recently. Therefore, better protection and monitoring of dry woodlands is urgently needed, and our analyses can provide a basis for context‐specific land‐use and conservation planning.European Research Council (ERC)Peer Reviewe
Gender and Migration in the Transnational Literary Field: The Case of Cameroonian Migrant Authors
No full textDie vorliegende Dissertation befasst sich mit der Verhandlung, Repräsentation und den Effekten von Gender und Migration im transnationalen literarischen Feld am Beispiel von in erster Generation emigrierten Autor*innen kamerunischer Herkunft, die auf Französisch und Englisch publizieren oder publiziert haben. Theoretisch bezieht sich die Arbeit hauptsächlich auf Bourdieus Literatursoziologie und deren transnationale und postkoloniale Weiterentwicklungen sowie auf feministische Theorien. Der erste Teil konkretisiert die Produktionsbedingungen und Rezeptionsmechanismen, die Autor*innen kamerunischer Herkunft im literarischen Feld positionieren und an denen sie partizipieren. Hierbei zeichnet sich zum einen die transnationale Tendenz ab, die Autor*innen auf ihren kamerunischen oder afrikanischen Hintergrund und sogenannte ‚afrikanische‘ Themen und Schreibstile zu verpflichten. Zum anderen wird deutlich, dass vergeschlechtlichte Stereotypen und Denkstrukturen in der Positionierung der Autor*innen eine wichtige Rolle spielen. Der zweite Teil der Arbeit widmet sich der Repräsentation und Verhandlung von Gender und Migration in Prosatexten von Autor*innen kamerunischer Herkunft. Hierbei wird eine chronologische Differenzierung in Bezug auf den Migrationsprozess vorgenommen: das erste Kapitel behandelt Texte, die die Migration der Figuren gewissermaßen vorbereiten, das zweite Narrative des Übergangs, das dritte Texte, deren Figuren im adoptierten Land bereits Wurzeln gefasst haben und das letzte Kapitel solche, in denen emigrierte Figuren in ihr Herkunftsland zurückkehren. Die Analysen stellen die unterschiedlichen Modi heraus, in denen sich Texte und Autor*innen auf inhaltlicher und ästhetischer Ebene auf ihr Herkunfts- und adoptiertes Land beziehen und verschiedene Geschlechterregimes miteinander vermitteln. Darüber hinaus wird dargestellt, wie verschiedene Texte dominante Rezeptionsmechanismen im literarischen Feld thematisieren, bestätigen oder subversiv unterlaufen.Taking the example of first-generation emigrant authors of Cameroonian origin writing in French or English, my thesis concerns itself with the representation, negotiation and effects of gender and migration in the transnational literary field. Pierre Bourdieu’s sociology of literature and its repercussions in postcolonial studies as well as feminist theories provide its main theoretical background. The first part illustrates the conditions of production and mechanisms of reception that position authors of Cameroonian origin in the literary field. It becomes clear that at both ends of the transnational field, authors are pinned down on their African background and are expected to commit themselves to so-called ‘African’ themes and styles. Gendered ideas and stereotypes are revealed to also play a significant role in authors’ positionings. The second part of the study focuses on the representation and negotiation of gender and migration in prose texts by authors of Cameroonian descent. The body of works is classified chronologically: the first chapter deals with narratives preceding characters’ emigration, the second chapter is concerned with transitional migration narratives, the third with narratives of immersion and the last chapter with texts in which emigrated characters return to their country of origin. My analyses highlight the different referential and aesthetic modes in which texts and authors refer to their home and adopted countries and how they negotiate different gender regimes. Furthermore, I map out the ways in which different texts take up, confirm or subvert mechanisms of reception that have been identified as dominant in the literary field
Welche Rolle spielt die Repräsentationsform von Messdaten für die Qualität der Lernergebnisse von Schüler:innen?
No full textRepräsentationen sind ein essenzieller Bestandteil des Physikunterrichts. Allgemein können sie, bei geeigneter Gestaltung, Schüler:innen in Lernprozessen unterstützen und ihre Ergebnisse beim Lösen von Aufgaben verbessern. Studien der Physikdidaktik zu Repräsentationen beschäftigen sich hauptsächlich mit dem Wissenserwerb oder der Wissensabfrage. Sie lassen keinen klaren Schluss zu, zeigen aber Unterschiede zwischen Lernenden auf, die mit jeweils verschiedenen Repräsentationen gearbeitet haben. Daher untersucht diese Arbeit, ob solche Unterschiede und speziell positive Effekte von Repräsentationen auch beim Auswerten von Messdaten auftreten. Darüber hinaus stellt sich die Frage, ob geeignete Repräsentationen zur Unterstützung der Auswertung existieren, da es hier vielfältige Schwierigkeiten gibt. Um dies zu überprüfen, wurde eine Studie mit 571 Schüler:innen durchgeführt. Dabei wurden Daten mit unterschiedlichen Repräsentationen ausgewertet. Die Ergebnisse wurden qualitativ mittels Kategoriensystemen bewertet und dann quantitativ mit ordinalen logistischen Regressionen untersucht. Die Resultate zeigen keinen Effekt der Repräsentationsform auf die Ergebnisse der Schüler:innen im Auswerten von Messdaten. Zudem moderiert der Cognitive Load den Effekt der Repräsentationsform nicht. Der Load beeinflusst die Auswertung aber direkt mit kleinen und mittleren Effektstärken. Den größten Einfluss haben die Kompetenzen der Schüler:innen im Auswerten von Messdaten. Denn die Ergebnisse für die Konstrukte Datenaufbereitung und Schlüsse ziehen deuten mittlere bis starke Effekte an. Da die Studie keine Effekte von Repräsentationen zeigen konnte, sollten die Gründe für das Eintreten und Ausbleiben positiver Einflüsse von Repräsentationen näher untersucht werden. Dennoch impliziert die Studie, dass Repräsentationen beim Auswerten von Messdaten genutzt werden können, um Barrieren zu reduzieren und so die Teilhabe aller Schüler:innen an Erkenntnisgewinnungsprozessen zu erleichtern.This research aims to explore whether the positive effects of representations also manifest when students are evaluated on their ability to analyse measurement data. Additionally, the study seeks to identify the most suitable representations for supporting this type of evaluation, as students often struggle in this area. To investigate this, a study was conducted with 571 students, in which they evaluated measurement data using different representations. The results were qualitatively assessed using category systems and then quantitatively analysed using ordinal logistic regression models. The results revealed that the form of representation did not significantly influence students' success in evaluating measurement data. Furthermore, there was no evidence that cognitive load moderated the effect of representation form on data evaluation. However, cognitive load does directly impact students' results, with small to medium effect sizes. The most significant factor affecting data evaluation is students' competency in this area. The results for competencies in data organisation and drawing conclusions indicate moderate to strong effects. As the study could not demonstrate positive or negative effects of representations on data evaluation, further research is required to understand why these influences are present or absent in physics education. Nevertheless, the study suggests that representations can reduce barriers and facilitate participation in knowledge acquisition processes by all students