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A quinolone N-oxide antibiotic selectively targets Neisseria gonorrhoeae via its toxin–antitoxin system
No full textGonorrhoea is a major sexually transmitted infection and the emergence of multidrug-resistant Neisseria gonorrhoeae poses a global health threat. To identify candidate antibiotics against N. gonorrhoeae , we screened Pseudomonas aeruginosa -derived secondary metabolites and found that 2-nonyl-4-quinolone N -oxide (NQNO) abrogated growth of N. gonorrhoeae in vitro. NQNO did not impair growth of commensal Neisseriae , vaginal lactobacilli or viability of human cells. Mechanistically, NQNO disrupted the electron transport chain, depleted ATP and NADH levels and increased oxidative stress. This triggered activation of a toxin–antitoxin system, release of the endogenous Zeta1 toxin and bacterial death. In a mouse model of infection, topical application of NQNO prevented colonization by N. gonorrhoeae . Chemical modification yielded 3-methyl NQNO, which exhibited nanomolar potency against multidrug-resistant strains, lack of resistance development and significantly reduced pathogen numbers during experimental infection of mice. These findings show the potential for selective killing of bacterial pathogens such as multidrug-resistant N. gonorrrhoeae through activation of endogenous toxins.publishe
Phylloclades of Jacksonia (Fabaceae) - leaf-like branches as adaptation to seasonally arid environments
No full textLeaves of seed plants were evolutionarily derived through syngenesis (fusion) of the photosynthetic cylindrical axes of the earliest land plants and subsequent morphological diversification. However, in some later evolved taxa leaves became very reduced or entirely lost and photosynthesis was again restricted to stems. Reduction of photosynthetic area to stems is mostly found in plants from arid environments and is generally considered disadvantageous in competition for light with plants with leaves but may be useful if water is limiting. For taxa that cannot form normal leaves on adult plants, increasing photosynthetic area is only possible by modification of other plant parts. Some taxa produce leaf-like phylloclades that are developmentally different from leaves. We investigated Jacksonia floribunda and J. anthoclada (Fabaceae) leaves and phylloclades. In all Jacksonia species true leaves are only developed in the earliest ontogenetic stages, and subsequently are reduced to minor, nonphotosynthetic brownish scales. After several nodes on the seedling, photosynthetic phylloclades, each inserted in the axil of a scale, form the foliage. Immature phylloclades have vestigial nonphotosynthetic leaves borne on small projections from the edge of the blade. These soon abscise. The phylloclades are flattened branches and when mature have a distinctly reticulate venation and a sinuous margin with alternating mucronate tips where the vestigial leaves were attached. Jacksonia species demonstrate a transformational series where in most species foliage is reduced to branchlets. In a few others branchlets are winged forming cladodes or are condensed and laterally expanded to form phylloclades. Our findings on the more derived species in Jacksonia illustrate the complexity of plant morphological responses to evolutionary pressures of seasonal water limitation.publishe
Umweltbelastungen durch die Sport- und Fahrgastschifffahrt – eine Übersicht : Bericht der Arbeitsgruppe Umweltphysik am Limnologischen Institut der Universität Konstanz für das SuBoLakes-Projekt der Deutschen Bundesstiftung Umwelt (Az. 35825/01)
No full textpublishe
From agents of the people to agents of authority? : How illiberal populism impacts interactions between regulatory agencies and external stakeholders
No full textThe decline in democratic quality and the increasing electoral popularity of illiberal populist parties are among the most notable global phenomena in the past 20 years. This article builds a bridge between the growing body of political science literature addressing how democratic backsliding impacts linkages between governments and organized interests and the public administration literature exploring how illiberal populists reshape the bureaucracy. Focusing on regulatory agencies in four post‐communist countries that have recently experienced varying degrees of democrating backsliding, we explore whether and how interactions between bureaucrats and interest groups have changed amid democratic decline. We find that even in the context of backsliding, professionalization (i.e. internal organizational development) and expertise provision are strong positive predictors of interest groups' access to regulators. However, our analysis unequivocally shows that exclusion by illiberal populist incumbent parties has a profound and negative effect on organizations' ability to reach bureaucracies. We draw on a new survey dataset, which grasps relationships between organized interests and political institutions (i.e. governments, parties, regulatory agencies, parliaments) in the region.publishe
Relaxation and Optimal Control of Age- and Space-structured Epidemic Models
No full textThis work addresses age- and space-structured epidemic models in two different ways: After introducing the well-known classical reaction-diffusion-like system, we introduce a novel approach to population movement which yields a model similar to wave or telegrapher's equations, and analyze existence of solutions and convergence to the classical model. In the second part, we add a control variable and show the existence of an optimal vaccination strategy, give first-order optimality conditions, and conclude with numerical experiments.publishe
Cracking Capuchins : Investigating stone tool use by white-faced capuchin monkeys using camera traps
No full textThe use of tools enables human and non-human animals alike to achieve goals that would otherwise be unattainable. Whether it is a human using a needle to sew clothing, bees placing feces on hive entrances to deter predators, or a chimpanzee fishing for termites with a thin stick — tool use in the animal kingdom manifests in diverse ways, reflecting the ecological challenges and cognitive adaptations of each species. Yet, despite occurring in many different taxa — from insects to primates — tool-using animals make up only a small fraction of all known animal species, suggesting that tool use has evolved several times independently. Understanding the factors that drive the emergence, persistence, and spread of tool use is of great interest, not only to better grasp the role tool use played in hominin evolution but also because of the remarkable variation observed both within and between
species. The evolution of tool use has been linked to various ecological, social, and cognitive factors, which often overlap and can be difficult to distinguish.
In this thesis, I use a unique study system to investigate what drives tool use to arise, persist, and spread in groups of animals. Since 2017, motion-triggered camera traps have been used to study the white-faced capuchin monkeys (Cebus capucinus imitator) living on the islands of Coiba and Jicarón in Panama, which have a tradition of stone tool use unique to the Cebus genus. These capuchins are uniquely suited to study the drivers of tool-use evolution, because tool-using and non-tool-using groups coexist in the same habitat, allowing for comparisons that exclude many ecological factors.
To better understand the variation in tool use between groups, it is necessary to examine how it varies within groups, as behavior spreads through individual dispersal. In chapter 1, I consider the striking male bias in tool use on Jicarón island. I show that females have the physical ability and opportunity to use tools, but do not engage in this behavior. This absence is not due to sampling bias, and has important implications for the cultural transmission of tool use. In chapter 2, I examine the development of tool use by comparing tool use proficiency between age classes. Using detailed frame-by-frame coding of one year of tool use events at two different experimental anvil sites, I show that the development of tool use proficiency is a slow process in which social attention and social tolerance play important roles. In chapter 3, I explore a potential ecological driver of the tool use behavior on Jicarón, namely the tidal cycles. Using a novel statistical approach, I compare the timing of coastal activity in relation to the tidal cycles between tool-using and non-tool-using capuchins. I find that tool-using capuchins show a stronger correlation of coastal activity with tidal cycles, suggesting that tool use facilitates more efficient exploitation of intertidal resources.
In chapter 4, I describe a previously undocumented social tradition of interspecies abduction. On Jicarón, the same capuchins that use tools have also begun to abduct and carry infant howler monkeys. This behavior suggests that the environmental and social conditions that favor innovation of tool use might also favor innovation more generally. Importantly, this chapter highlights that innovations can emerge and spread via social learning even in the absence of a clear functional advantage. In chapter 5, I examine one possible consequence of tool use by comparing social cohesion between a tool-using group and a non-tool-using group. Because stone tool use relies on hammerstones and anvils, which can be monopolized by individuals, it is likely to increase within-group competition. I found that, in order to overcome this competition, the tool-using group may have become less socially cohesive. Notably, this shift in social structure affects not only tool-using males but the entire group, with cascading effects on within- and between-group dynamics.
Taken together, these chapters highlight that tool use is likely to require a combination of many factors to develop. My findings suggest that conditions conducive to innovation of tool use may also facilitate innovation more broadly and that islands may provide unique environments in which these factors co-occur. Furthermore, I propose that once localized tool-use traditions emerge, they may drive secondary behavioral differences, such as changes in social cohesion, that further differentiate tool-using and non-tool-using individuals. Finally, I demonstrate the power of camera traps as a non-invasive method for studying the behavior of unhabituated, wild primates in great detail, providing insights into everything from spatial and temporal activity patterns to the emergence and spread of a novel cultural tradition.publishe
Nutational resonance modes in antiferromagnetic materials
No full textThe Landau–Lifshitz–Gilbert (LLG) equation is well-established to describe the spin dynamics of magnetic materials. This first-order differential equation is based on the assumption that the spin angular momenta and corresponding magnetic moments are always parallel. While this assumption is largely unproblematic, both theoretical considerations and experimental results have indicated that the two may become separated on ultrafast timescales, giving rise to inertial dynamics along with a modified spin wave dispersion. Here, we apply linear spin wave theory to the inertial LLG equation to compute the eigenmodes of the altermagnetic materials SmErFeO3 and α-Fe2O3. We find the largest influence of nutation on the magnetic resonances in the case of hematite, which exhibits both a sizeable shift of the resonance frequencies as compared to the inertia-free case and additional nutational resonances that are in a similar order of magnitude to the materials’ higher-frequency precessional exchange modes. While the realistic magnitude of the inertial parameter remains an open question, we hope that our quantitative analysis provides the starting point for further experimental investigations.publishe
How user language affects conflict fatality estimates in ChatGPT
No full textOpenAI’s ChatGPT language model has gained popularity as a powerful tool for problem-solving and information retrieval. However, concerns arise about the reproduction of biases present in the language-specific training data. In this study, we address this issue in the context of the Israeli–Palestinian and Turkish–Kurdish conflicts. Using GPT-3.5, we employed an automated query procedure to inquire about casualties in specific airstrikes, in both Hebrew and Arabic for the former conflict and Turkish and Kurdish for the latter. Our analysis reveals that GPT-3.5 provides 34 ± 11% lower fatality estimates when queried in the language of the attacker than in the language of the targeted group. Evasive answers denying the existence of such attacks further increase the discrepancy. A simplified analysis on the current GPT-4 model shows the same trends. To explain the origin of the bias, we conducted a systematic media content analysis of Arabic news sources. The media analysis suggests that the large-language model fails to link specific attacks to the corresponding fatality numbers reported in the Arabic news. Due to its reliance on co-occurring words, the large-language model may provide death tolls from different attacks with greater news impact or cumulative death counts that are prevalent in the training data. Given that large-language models may shape information dissemination in the future, the language bias identified in our study has the potential to amplify existing biases along linguistic dyads and contribute to information bubbles.publishe
Zeiten-Geschichte
No full textDas erste Problem in der (nicht nur historischen) Auseinandersetzung mit Zeit ist, sie überhaupt zu einem Problem zu machen. Im Alltagsverständnis wird Zeit als eine außerhalb von Menschen und Gesellschaften angesiedelte Gegebenheit betrachtet, die unabhängig von deren Wollen und Wirken abläuft und ihre nahezu unerbittliche Macht ausübt. Ein Blick auf die Uhr oder die Veränderung der Natur im Wandel der Jahreszeiten belegt es vermeintlich zur Genüge: Zeit ist dort draußen, und sie läuft ab. Zeit kann daher einerseits als sehr trivial erscheinen – und erweist sich andererseits als ungemein komplex, geradezu rätselhaft. Denn bereits ein zweiter Blick auf das Phänomen ‚Zeit‘ zeigt, dass die vor mehr als eineinhalb Jahrtausenden getätigte Aussage des Augustinus weiterhin gültig ist, dass man so lange kein Problem mit der Zeit haben muss, so lange man nicht danach gefragt wird (Augustinus 1987).publishe
When morphology is not enough : The acquisition of voice in monolingual Greek children and bilingual children with Greek as a heritage language
No full textThe acquisition of voice in Greek remains understudied, especially in heritage populations. Voice in Greek poses a challenging acquisition task for children due to its syncretism, marking various verb classes as well as passives. The present study explores the acquisition of anticausatives, reflexives, and passives in 6-to-8-year-old monolingual Greek and Greek-German bilingual children with Greek as their heritage language. This age coincides with the immersion of children in the education system. A Sentence Picture Matching task tested participants’ interpretation preferences when ambiguity arises in reflexives and (optionally) (un)marked anticausatives (reflexive/anticausative vs. passive interpretation); it also tested accuracy in passives compared to actives-transitives (passive vs. active interpretation). All children exhibited adult-like performance in reflexives. In anticausatives, despite their lower performance, they were qualitatively similar to adults, exhibiting knowledge of verb classes. Children’s preferences were predicted by age (active-morphology/ACT) and vocabulary (non-active/NACT), confirming the role of the mental lexicon in the acquisition of NACT anticausatives. The only difference between bilingual and monolingual children was in optionally (un)marked anticausatives, both in ACT and NACT, that was marginally predicted by age and grammar production respectively, suggesting that optionality affects bilingual more than monolingual children. In passives, children were less accurate than adults despite ceiling performance in actives-transitives. Bilingual children performed less well than monolingual children and performance was predicted by grammar and exposure. These findings reflect the difficulties of monolingual children with passives and their late acquisition which further affects bilingual development due to reduced input in heritage Greek.publishe