Auf dieser Seite finden Sie die chronologisch geordneten Veröffentlichungen unserer Wissenschaftler*innen aus den vergangenen Jahren.
Aktuelle Publikationen (Politik- und Verwaltungswissenschaft)
(2023): Dynamical Gauge Fields with Bosonic Codes Physical Review Letters ; 130 (2023), 17. - 171901. - American Physical Society (APS). - ISSN 0031-9007. - eISSN 1079-7114
The quantum simulation of dynamical gauge field theories offers the opportunity to study complex high-energy physics with controllable low-energy devices. For quantum computation, bosonic codes promise robust error correction that exploits multiparticle redundancy in bosons. Here, we demonstrate how bosonic codes can be used to simulate dynamical gauge fields. We encode both matter and dynamical gauge fields in a network of resonators that are coupled via three-wave mixing. The mapping to a Z2 dynamical lattice gauge theory is established when the gauge resonators operate as Schrödinger cat states. We explore the optimal conditions under which the system preserves the required gauge symmetries. Our findings promote realizing high-energy models using bosonic codes.
(2023): Contestations, appropriations et productions de savoirs par les femmes : Réflexions sur les catégories d’analyse d’un champ de recherche émergent Critique Internationale ; 99 (2023), 2. - S. 11-18. - CAIRN. - ISSN 1290-7839. - eISSN 1777-554X
(2023): Le livre des sciences est un livre ouvert Critique Internationale ; 99 (2023), 2. - S. 89-105. - CAIRN. - ISSN 1290-7839. - eISSN 1777-554X
(2023): Femtosecond Frequency Combs with Few‐kHz Passive Stability over an Ultrabroadband Spectral Range Laser & Photonics Reviews ; 2023. - Wiley. - ISSN 1863-8880. - eISSN 1863-8899
Femtosecond frequency combs are among the most precise measurement tools in existence. They have applications ranging from high-precision spectroscopy and metrology to time-domain quantum physics. Maximizing the passive stability of these instruments is essential to achieve their full potential in fundamental science and high-tech industry. However, the noise mechanisms across the entire operating space of these devices have not been fully characterized. Here the noise properties of fiber-based frequency combs are studied as a function of intracavity dispersion, pump power, and repetition rate. Distinct minima are discovered in this parameter space where the free-running linewidth of the carrier-envelope offset (CEO) frequency fCEO drops below 1 kHz. The individual comb lines are analyzed spread over a wide spectral range producing a complete understanding of the particular contributions to the phase noise and their interplay. Exploiting these findings, combs featuring sharp teeth at specific frequency positions and over the entire spectrum from fCEO to 300 THz are demonstrated. The ultrabroadband stability offered by these compact systems provides a new level of quality for front-end measurement tasks in both time and frequency domains.
(2023): On the beauty of vases : Birkhoff’s aesthetic measure versus Hogarth’s line of beauty Frontiers in Psychology ; 14 (2023). - 1114793. - Frontiers. - eISSN 1664-1078
Vases continue to be important aesthetic objects in almost all developed cultures. Nevertheless, there is little to no systematic research on the shape characteristics that determine their beauty. A famous exception is Birkhoff, who in his 1933 book used the geometric ratios of vases to calculate their beauty. One form factor that he discussed theoretically but did not include in his aesthetic measure is the outline curvature of vases. This is despite the fact that William Hogarth recognized curvature as relevant to the aesthetic evaluation of forms as early as 1753, demonstrating this with his Line of Beauty. Given the great influence of these two ideas, the aim of the present study was to examine their contribution to the aesthetics of vases. For this objective, we designed a set of symbolic vases by systematically varying width and curvature, and asked participants to rate their beauty in an online experiment. The results show that both geometric ratios and curvature contribute to the beauty of the vases.
(2023): Without Exemptions : Reconciling Equality with the Accommodation of Diversity Res Publica ; 2023. - Springer. - ISSN 1356-4765. - eISSN 1572-8692
When generally applicable rules clash with one’s cultural, religious or moral commitments, should exemptions be granted? The debate on exemptions raises the question both of what it means to treat people equally and of what it means to protect diversity adequately. The objective of this paper is to defend the no-exemption argument and to make it a more attractive position for liberals. I first argue that exemptions violate the principle of equal treatment because they rely on distinctions that cannot be neutrally justified. I then argue that diversity can be adequately accommodated if we use a more demanding interpretation of the justification of generally applicable rules. There should be no exemption to fully justified rules, but rules are only fully justified when the particular demands that they impose on individuals are justified, i.e. when they are either neutral or pass both a Necessity Test and a Sufficiency Test. When rules are not fully justified, they should be repealed or modified. Based on this focus on the demands of rules, equality can be reconciled with an adequate accommodation of diversity.
(2023): Development, predictors, and effects of trainees’ organizational identification during their first year of vocational education and training Frontiers in Psychology ; 14 (2023). - 1148251. - Frontiers. - eISSN 1664-1078
Development, predictors, and effects of trainees’ organizational identification during their first year of vocational education and training
The vocational identity of trainees is one component of their professional competence and is considered to be a central goal of vocational education and training (VET) programs. From the numerous identity constructs and conceptualizations, this study focuses on the organizational identification of trainees, that is, the extent to which trainees internalize the values and goals of their training company and perceive themselves as part of this company. We are specifically interested in the development, predictors, and effects of trainees’ organizational identification, as well as the interrelations between organizational identification and social integration. We use longitudinal data of n = 250 trainees in dual VET programs in Germany at the very beginning of their VET program (t1), after 3 months (t2), and after 9 months (t3). A structural equation model was used to analyze the development, predictors, and effects of organizational identification for the first 9 months of training and the cross-lagged effects between organizational identification and social integration. The results showed a high stability of trainees’ organizational identification over the first 9 months. Regarding the predictors, the results indicated positive direct and indirect effects of the formal socialization tactics implemented by the training company, as well as of support by the trainer at the beginning of the training. However, collegial support at the beginning of the training did not seem to play a significant role in organizational identification. Moreover, organizational identification positively affected trainees’ emotional engagement and self-perceived competence while negatively predicting dropout intentions after 9 months of training. Finally, the cross-lagged effects between organizational identification and social integration were not significant, and only at t3 were these constructs positively correlated. However, regarding the development, predictors, and effects, very similar results were found for organizational identification and social integration. The results underline the positive significance of organizational identification for the individual, the company, and society, even at this early stage of training. The results are discussed regarding both their scientific and practical implications.
(2023): Trait based niche differentiation in tetrakas (Bernieridae) endemic to Madagascar : A multi-isotope approach Frontiers in Ecology and Evolution ; 11 (2023). - 1082226. - Frontiers. - eISSN 2296-701X
Trait based niche differentiation in tetrakas (Bernieridae) endemic to Madagascar : A multi-isotope approach
Introduction: Tropical rainforest species interact with each other and their environment over a wide range of spatiotemporal scales. However, our understanding of resource partitioning and the mechanisms of avian species coexistence is largely restricted to subjective visual observations or acoustic monitoring. Therefore, the relative magnitudes of interspecific and intraspecific differences in resource use have remained difficult to quantify, particularly regarding different diets and habitat use. The eastern rainforest belt of Madagascar is inhabited by several species of insectivorous tetrakas belonging to an endemic bird family of Madagascar (Bernieridae). These species occupy similar habitats in the forest understory and are morphologically similar but because of likely differences (e.g., in foraging behaviors) we expect their foraging niches to be segregated allowing coexistence.
Methods: We examined the niche differentiation of four of these species: the Grey-crowned Tetraka ( Xanthomixis cinereiceps ), Long-billed Tetraka ( Bernieria madagascariensis ), Spectacled Tetraka ( Xanthomixis zosterops ), and White-throated Oxylabes ( Oxylabes madagascariensis ) in the Maromizaha rainforest in eastern Madagascar combining morphometry with stable carbon, nitrogen, and sulfur isotope ratios (δ 13 C, δ 15 N, and δ 34 S) from feathers.
Results: We show considerable variation in isotopic niche positions, niche breadth and interspecific niche overlap. In two species, the Long-billed Tetraka and Spectacled Tetraka, we found an indication of sex-specific niche space, with males exhibiting a larger isotopic niche-area relative to females. Morphological traits of five species (including the Wedge-tailed Tetraka, Hartertula flavoviridis ) coupled with stable isotope data provided explanations of patterns of niche overlap and isotopic position.
Discussion: The observed isotopic niche differences may be explained by differences in resource acquisition strategies that might be associated with specific morphological traits and spatial distribution. This may play an important role in niche differentiation among coexisting and phylogenetically closely related species.
(2023): Gleichheit, die ich meine Frankfurter Allgemeine Sonntagszeitung ; Nr. 15 vom 16. Apr. 2023. - S. 60
(2023): Multi‐dimensional Methods in Biological
NMRTwo‐Dimensional (2D) NMR Methods / Ivanov, Konstantin; Madhu, P.K.; Rajalakshmi, G. (Hrsg.). - Hoboken, NJ : Wiley, 2023. - S. 333-364. - ISBN 9781119806691
High-resolution NMR spectroscopy provides a large variety of experimental approaches that target on the characterization of samples at atomic resolution. This capacity is of special interest when it comes to the investigation of biological molecules to obtain insights into their inherent structural and dynamical features and ultimately, their functionality. Consequently, it emerged as one of the leading methodologies in structural biology, life science, and biophysics. The correlation of different nuclear spins and an increase in the number of dimensions sort out the problem of overlapping resonance signals which is commonly present in one-dimensional NMR spectroscopy. While three- and even higher dimensional NMR experiments are usually acquired to unambiguously achieve resonance assignment, two-dimensional NMR spectra such as heteronuclear 1H-15N and 1H-13C HSQC approaches can report on subtle conformational and dynamical changes and are thus an integral part in the large variety of sophisticated experiments. This chapter aims to show the strength of NMR spectroscopy especially when it is performed in multi dimensions on biomolecules that vary in type and composition as well as in the environment in which they are existing. Thus, the importance of modern NMR techniques in the context of in vivo as well as integrative approaches is discussed. Another pillar of this Chapter comprises case studies. Here, also non-standard (“exotic”) applications of NMR correlating nuclei are highlighted. The diversity of experimental possibilities multi-dimensional high-resolution NMR spectroscopy offers suggest a continuous expansion of applications on biomolecules. This dynamic development is strongly promoted by the permanent increase in instrumental sensitivity and performance.
(2023): From the shallow to the mesophotic : a characterization of Symbiodiniaceae diversity in the Red Sea NEOM region Frontiers in Marine Science ; 10 (2023). - 1077805. - Frontiers. - eISSN 2296-7745
From the shallow to the mesophotic : a characterization of Symbiodiniaceae diversity in the Red Sea NEOM region
The northern Red Sea has been coined a refuge for reef corals due to the exceptional thermal tolerance of these organisms. With ocean warming threatening coral reefs worldwide, a panoptic characterization of corals living in extreme conditions may provide insights into future responses of corals to environmental change. Among other factors, the genotype of the endosymbiotic algae in the family Symbiodiniaceae has been shown to have major implications on the distribution and resilience of their coral hosts. In this study, we aim at genotyping the Symbiodiniaceae communities associated with three depth generalist and one depth specialist coral species, characterized by the ability to withstand environmental conditions that are apparently limiting for other corals and occurring in a unique geographical region.
We sampled 50 corals from the northern Saudi Arabian Red Sea and the Gulf of Aqaba, covering a 97 m bathymetric gradient. We used high-throughput ITS2 gene sequencing and recovered different patterns of host–algal associations.
Results and discussion
The majority of the recovered algal genotypes appeared host- and environment-specific, while others were more widely distributed. At large, coral specimens were overwhelmingly associated with symbionts from the genus Cladocopium and specifically with many previously undescribed genotypes. This suggests the selection of specific genotypes, which might confer resistance and/or resilience to their host counterparts. Interestingly, we found a limited association with Durusdinium spp. and other known tolerant taxa in mesophotic corals in the northern Red Sea, but not in the Gulf of Aqaba. The broad absence of Durusdinium spp., typically ascribed to be stress tolerant, warrants further investigation into Symbiodiniaceae species that convey environmental resilience. Our data will serve as a baseline to explore the occurrence of specific symbionts that might be contributing to coral acclimation and adaptation and to assay how biodiversity might be impacted if subjected to increasing stressors.
We investigate squeezing of magnons in a conical spin spiral configuration. We find that while the energy of magnons propagating along the k and the −k directions can be different due to the non-reciprocal dispersion, these two modes are connected by the squeezing, hence can be described by the same squeezing parameter. The squeezing parameter diverges at the center of the Brillouin zone due to the translational Goldstone mode of the system, but the squeezing also vanishes for certain wave vectors. We discuss possible ways of detecting the squeezing.
(2023): No Zeitenwende (yet) : Early Assessment of German Public Opinion Toward Foreign and Defense Policy After Russia’s Invasion of Ukraine Politische Vierteljahresschrift ; 2023. - Springer. - ISSN 0032-3470. - eISSN 1862-2860
No Zeitenwende (yet) : Early Assessment of German Public Opinion Toward Foreign and Defense Policy After Russia’s Invasion of Ukraine
This paper addresses the question of whether Russia’s invasion of Ukraine led to a turning point ( Zeitenwende ) in public opinion on foreign and defense policy in Germany. To this end, we provide a theoretical analysis of how the concept of turning point can be applied to public opinion. We identify the durability of the change in attitudes as well as its significance as necessary conditions to speak of a turning point. In the remainder of the paper, we focus on the argument that changes in different types of orientations are significant to different degrees. Change in core postures is more significant than change in policy attitudes; change in attitudes thematically distant from the Russian invasion is more significant than change in attitudes directly related to the event. Empirically, we present a panel data analysis of attitude change triggered by the Russian invasion. Analysis of data from several waves of the German Longitudinal Election Study (GLES) panel survey collected before the invasion (2017–2021) and in two waves after (May and October 2022) shows that there were sizable shifts in policy attitudes directly related to the event. Postures remained essentially unchanged, as did thematically distant attitudes. We conclude that there has been no turning point at the level of public opinion (yet).
(2023): The impact of land use on non-native species incidence and number in local assemblages worldwide Nature Communications ; 14 (2023), 1. - 2090. - Springer. - eISSN 2041-1723
While the regional distribution of non-native species is increasingly well documented for some taxa, global analyses of non-native species in local assemblages are still missing. Here, we use a worldwide collection of assemblages from five taxa - ants, birds, mammals, spiders and vascular plants - to assess whether the incidence, frequency and proportions of naturalised non-native species depend on type and intensity of land use. In plants, assemblages of primary vegetation are least invaded. In the other taxa, primary vegetation is among the least invaded land-use types, but one or several other types have equally low levels of occurrence, frequency and proportions of non-native species. High land use intensity is associated with higher non-native incidence and frequency in primary vegetation, while intensity effects are inconsistent for other land-use types. These findings highlight the potential dual role of unused primary vegetation in preserving native biodiversity and in conferring resistance against biological invasions.
(2023): Rosenbergiella meliponini D21B Isolated from Pollen Pots of the Australian Stingless Bee Tetragonula carbonaria Microorganisms ; 11 (2023), 4. - 1005. - MDPI AG. - eISSN 2076-2607
Rosenbergiella meliponini D21B Isolated from Pollen Pots of the Australian Stingless Bee Tetragonula carbonaria
Rosenbergiella bacteria have been previously isolated predominantly from floral nectar and identified in metagenomic screenings as associated with bees. Here, we isolated three Rosenbergiella strains from the robust Australian stingless bee Tetragonula carbonaria sharing over 99.4% sequence similarity with Rosenbergiella strains isolated from floral nectar. The three Rosenbergiella strains (D21B, D08K, D15G) from T. carbonaria exhibited near-identical 16S rDNA. The genome of strain D21B was sequenced; its draft genome contains 3,294,717 bp, with a GC content of 47.38%. Genome annotation revealed 3236 protein-coding genes. The genome of D21B differs sufficiently from the closest related strain, Rosenbergiella epipactidis 2.1A, to constitute a new species. In contrast to R. epipactidis 2.1A, strain D21B produces the volatile 2-phenylethanol. The D21B genome contains a polyketide/non-ribosomal peptide gene cluster not present in any other Rosenbergiella draft genomes. Moreover, the Rosenbergiella strains isolated from T. carbonaria grew in a minimal medium without thiamine, but R. epipactidis 2.1A was thiamine-dependent. Strain D21B was named R. meliponini D21B, reflecting its origin from stingless bees. Rosenbergiella strains may contribute to the fitness of T. carbonaria.
(2023): Increasing digitalization is associated with anxiety and depression : a Google Ngram analysis PLOS ONE ; 18 (2023), 4. - e0284091. - Public Library of Science (PLoS). - eISSN 1932-6203
The prevalence of anxiety disorders and depression are rising worldwide. Studies investigating risk factors on a societal level leading to these rises are so far limited to social-economic status, social capital, and unemployment, while most such studies rely on self-reports to investigate these factors. Therefore, our study aims to evaluate the impact of an additional factor on a societal level, namely digitalization, by using a linguistic big data approach. We extend related work by using the Google Books Ngram Viewer (Google Ngram) to retrieve and adjust word frequencies from a large corpus of books (8 million books or 6 percent of all books ever published) and to subsequently investigate word changes in terms of anxiety disorders, depression, and digitalization. Our analyses comprise and compare data from six languages, British English, German, Spanish, Russian, French, and Italian. We also retrieved word frequencies for the control construct “religion”. Our results show an increase in word frequency for anxiety, depression, and digitalization over the last 50 years (r = .79 to .89, p < .001), a significant correlation between the frequency of anxiety and depression words (r = .98, p < .001), a significant correlation between the frequency of anxiety and digitalization words (r = .81, p < .001), and a significant correlation between the frequency of depression and anxiety words (r = .81, p < .001). For the control construct religion, we found no significant correlations for word frequency over the last 50 years and no significant correlation between the frequency of anxiety and depression words. Our results showed a negative correlation between the frequency of depression and religion words (r = -.25, p < .05). We also improved the method by excluding terms with double meanings detected by 73 independent native speakers. Implications for future research and professional and clinical implications of these findings are discussed.
(2023): Wertschöpfung und soziale Innovation für eine neue Generation von Bibliotheken in der EU : Neues EU-Horizon-2020-Projekt zu Bibliotheksinnovationen (LibrarIn) Bibliothek Forschung und Praxis ; 47 (2023), 1. - S. 170-171. - De Gruyter. - ISSN 0341-4183. - eISSN 1865-7648
(2023): The ubiquitin-like modifier FAT10 is degraded by the 20S proteasome in vitro but not in cellulo Life Science Alliance ; 6 (2023), 6. - e202201760. - Life Science Alliance, LLC. - eISSN 2575-1077
Ubiquitin-independent protein degradation via the 20S proteasome without the 19S regulatory particle has gained increasing attention over the last years. The degradation of the ubiquitin-like modifier FAT10 by the 20S proteasome was investigated in this study. We found that FAT10 was rapidly degraded by purified 20S proteasomes in vitro, which was attributed to the weak folding of FAT10 and the N-terminally disordered tail. To confirm our results in cellulo, we established an inducible RNA interference system in which the AAA-ATPase Rpt2 of the 19S regulatory particle is knocked down to impair the function of the 26S proteasome. Using this system, degradation of FAT10 in cellulo was strongly dependent on functional 26S proteasome. Our data indicate that in vitro degradation studies with purified proteins do not necessarily reflect biological degradation mechanisms occurring in cells and, therefore, cautious data interpretation is required when 20S proteasome function is studied in vitro.
(2023): War and pandemic do not jeopardize Germans’ willingness to support climate measures Communications Earth & Environment ; 4 (2023), 1. - 101. - Springer. - eISSN 2662-4435
How do the impacts of acute crises influence citizens’ willingness to support different types of climate measures? An acute crisis can be understood either as an impediment or as an opportunity for climate change mitigation. In the first perspective, crisis impacts would create negative spill-overs and dampen citizens’ willingness to support climate action, while in the second perspective, the opposite would occur. Based on a survey experiment fielded in Germany in 2022 ( n = 5438), we find that the economic implications of the Russo-Ukrainian War do not decrease behavioral willingness, while restrictions of civil liberties to combat the COVID-19 pandemic lead to higher climate support, underpinning the crisis-as-opportunity perspective. Willingness to support climate measures is strongest among (1) those most concerned about climate change, and (2) those who trust the government. We conclude that individuals do not wish climate change mitigation to be deprioritized on the back of other crises.
(2023): Did Ghana Do Enough? : A Scientometric Analysis of COVID-19 Research Output from Ghana within the African Context Diseases ; 11 (2023), 2. - 56. - MDPI. - eISSN 2079-9721
Did Ghana Do Enough? : A Scientometric Analysis of COVID-19 Research Output from Ghana within the African Context
The COVID-19 pandemic has generated worldwide research efforts to provide knowledge about the disease. Yet little is known about how Ghana contributed to this critical knowledge production. This scientometric analysis was conducted to ascertain Ghana’s COVID-19 research output within the African context to gain understanding and identify potential future directions. The study retrieved relevant research, spanning 2019 to 2022, from the Scopus database in December 2022. The retrieved data were assessed using various established indices, including collaboration patterns, productive institutions, citation patterns, and major research sponsors, among others. Ghana came seventh in Africa with a total of 1112 publications. For international collaborations, the United States and the United Kingdom were the major partners, while South Africa was the main African collaborator with Ghana. Out of the top 21 most productive authors, 85.7% were males and 14.3% were females, demonstrating a great gender gap in research output in Ghana. Although Ghana has made some contributions to the global COVID-19 research output, there are few intra-continental research collaborations, which limits Africa’s overall research output. Our study demonstrates a critical need for the Ghanaian government to prioritize research and funding and address barriers to women’s research productivity.