Organic radical batteries (ORBs) are a promising class of electrochemical power sources employing organic radicals as redox-active groups. This article reports on the development of a versatile on-substrate electrode setup for spectroelectrochemical Electron Paramagnetic Resonance (EPR) measurements on redox conductive polymers for ORBs. Quantitative in operando EPR experiments performed on electrochemical cells with a di-TEMPO Ni-Salen polymer as active electrode material demonstrate a strong decrease in the number of paramagnetic centers upon oxidizing the film. The distinct EPR signatures of the TEMPO-containing polymer and its fragments in different molecular environments are used to study its degradation upon repeated cycling. A comparison between the number of EPR-active sites and the number of electrochemically active charges, as measured by cyclic voltammetry, provides information on the nature of the degradation process. Low-temperature ex situ pulse EPR measurements on the oxidized polymer film reveal the spectrum of dilute nitroxide species, which may be associated with electrochemically inactive islands. These experiments pave the way for advanced EPR techniques for accurately determining distances between adjacent paramagnetic centers and thus for identifying performance-limiting loss mechanisms, which can eventually help develop strategies for making ORBs powerful contenders on the path towards sustainable electrochemical power sources.
View lessThe theoretical and empirical foundations of research on trust in education are still weak. To contribute to a better understanding of the role of trust in educational systems, this final article of the special issue “Trust in educational settings. European perspectives” highlights the findings from the contributions in this special issue and links them to insights and concepts from interdisciplinary trust research. Furthermore, it identifies and discusses seven avenues for future research on trust in educational settings. Thus, this paper and the special issue as a whole aim to highlight relevant avenues for future research, thereby strengthening research on trust in education.
View lessThis editorial paper introduces the relevance of trust in educational settings. It discusses interdisciplinary approaches to trust, reflects upon the relationships between trust and education and how trust has so far been studied in educational research. In addition, a comprehensive model of trust is introduced as a framework for the individual papers of this special issue that altogether, through different disciplinary and methodological lenses, investigate trust in various realms of education in five European countries.
View lessBased on existing studies on welfare and education regimes, the paper aims at strengthening the conceptual foundations of comparative research in education and trust by identifying relevant system-level characteristics, deriving analytical dimensions as a framework for cross-national comparison, and exploring how these dimensions might be linked to trust. The paper thus provides a better basis for dealing with context as well as its role in causal explanations and case selection in cross-national comparative research on trust in education.
View lessLocal biodiversity patterns are expected to strongly reflect variation in topography, land use, dispersal boundaries, nutrient supplies, contaminant spread, management practices, and other anthropogenic influences. Contrary to this expectation, studies focusing on specific taxa revealed a biodiversity homogenization effect in areas subjected to long-term intensive industrial agriculture. We investigated whether land use affects biodiversity levels and community composition (α- and β-diversity) in 67 kettle holes (KH) representing small aquatic islands embedded in the patchwork matrix of a largely agricultural landscape comprising grassland, forest, and arable fields. These KH, similar to millions of standing water bodies of glacial origin, spread across northern Europe, Asia, and North America, are physico-chemically diverse and differ in the degree of coupling with their surroundings. We assessed aquatic and sediment biodiversity patterns of eukaryotes, Bacteria, and Archaea in relation to environmental features of the KH, using deep-amplicon-sequencing of environmental DNA (eDNA). First, we asked whether deep sequencing of eDNA provides a representative picture of KH aquatic biodiversity across the Bacteria, Archaea, and eukaryotes. Second, we investigated if and to what extent KH biodiversity is influenced by the surrounding land use. We hypothesized that richness and community composition will greatly differ in KH from agricultural land use compared with KH in grasslands and forests. Our data show that deep eDNA amplicon sequencing is useful for in-depth assessments of cross-domain biodiversity comprising both micro- and macro-organisms, but has limitations with respect to single-taxa conservation studies. Using this broad method, we show that sediment eDNA, integrating several years to decades, depicts the history of agricultural land-use intensification. Aquatic biodiversity was best explained by seasonality, whereas land-use type explained little of the variation. We concluded that, counter to our hypothesis, land use intensification coupled with landscape wide nutrient enrichment (including atmospheric deposition), groundwater connectivity between KH and organismal (active and passive) dispersal in the tight network of ponds, resulted in a biodiversity homogenization in the KH water, leveling off today's detectable differences in KH biodiversity between land-use types. These findings have profound implications for measures and management strategies to combat current biodiversity loss in agricultural landscapes worldwide.
View lessThe study presents the results of a standardized content analysis comparing the use of Twitter as an information source on the websites of five news media types (quality newspapers, a tabloid newspaper, weekly magazines, broadcasters, and internet only). The theoretical assumption behind the study is that the adoption of Twitter as a source follows the established practices of a particular media type. All articles published online by ten German news media in a period of one month were collected (n = 21,823). A subset of articles containing Twitter-related keywords (n = 496) and 375 tweets cited in these articles was explored in detail. Our focal analysis of n = 287 articles using Twitter as an information source revealed systematic differences between both media types and article topics regarding the number and style of Twitter references as well as the types of accounts cited. We found that the tabloid paper incorporated the highest number of tweets per article, incorporated tweets primarily in articles on human interest and gossip and cited non-elite sources more often than other media types. Quality papers, weekly magazines, and broadcasters used tweets as sources primarily in articles on politics and economy and cited public actors, such as politicians or officials, more frequently.
View lessThe development of novel earth-abundant metal-based catalysts to accelerate the sluggish oxygen evolution reaction (OER) is crucial for the process of large-scale production of green hydrogen. To solve this bottleneck, herein, a simple one-pot colloidal approach is reported to yield crystalline intermetallic nickel silicide (Ni2Si), which results in a promising precatalyst for anodic OER. Subsequently, an anodic-coupled electrosynthesis for the selective oxidation of organic amines (as sacrificial proton donating agents) to value-added organocyanides is established to boost the cathodic reaction. A partial transformation of the Ni2Si intermetallic precatalyst generates a porous nickel(oxy)hydroxide phase modified with oxidic silicon species as unequivocally demonstrated by a combination of quasi in situ Raman and X-ray absorption spectroscopy as well as ex situ methods. The activated form of the catalyst generates a geometric current density of 100 mA cm−2 at an overpotential (η100) of 348 mV displaying long-term durability over a week and high efficiency in paired electrolysis.
View lessThere is an increased interest in the determination of RNA structures in vivo as it is now possible to probe them in a high-throughput manner, e.g. using SHAPE protocols. By now, there exist a range of computational methods that integrate experimental SHAPE-probing evidence into computational RNA secondary structure prediction. The state-of-the-art in this field is currently provided by computational methods that employ the minimum-free energy strategy for prediction RNA secondary structures with SHAPE-probing evidence. These methods, however, rely on the assumption that transcripts in vivo fold into the thermodynamically most stable configuration and ignore evolutionary evidence for conserved RNA structure features. We here present a new computational method, ShapeSorter, that predicts RNA structure features without employing the thermodynamic strategy. Instead, ShapeSorter employs a fully probabilistic framework to identify RNA structure features that are supported by evolutionary and SHAPE-probing evidence. Our method can capture RNA structure heterogeneity, pseudo-knotted RNA structures as well as transient and mutually exclusive RNA structure features. Moreover, it estimates P-values for the predicted RNA structure features which allows for easy filtering and ranking. We investigate the merits of our method in a comprehensive performance benchmarking and conclude that ShapeSorter has a significantly superior performance for predicting base-pairs than the existing state-of-the-art methods.
View lessDie Statistik als fachliche Disziplin muss sich in einem rasch wandelnden Umfeld behaupten, das durch den Aufstieg der Data Science, den Bedeutungszuwachs der künstlichen Intelligenz sowie neue Datenstrukturen charakterisiert wird. Wie kann sich die Statistik hier behaupten oder verlorenes Terrain wiedergewinnen? Unter dem provokanten Motto „Make Statistics great again“ wurden aus verschiedenen Blickwinkeln Entwicklungen, Strategien und positive Beispiele skizziert, wie sich das Fach Statistik an der Universität, im Wissenschaftsbetrieb und auf dem Arbeitsmarkt positionieren sollte. Willi Seidel schaut aus dem Blickwinkel eines Hochschulpräsidenten auf den Ressourcenkampf der Fächer. Christine Müller berichtet über die Initiativen der Dachorganisation DAGStat die vielen Teildisziplinen der Statistik wirkungsvoll im Wissenschaftsbetrieb und in der Öffentlichkeit zu positionieren. Florian Meinfelder dokumentiert den Aufstieg des Masterstudiengangs in Survey Statistik zu einem der nachgefragtesten Studiengänge der Uni Bamberg. Jürgen Chlumsky und Markus Zwick beleuchten die historische Wahrnehmung der Amtsstatistik bei Pflichterhebungen und die Entwicklung der Forschungsdatenzentren sowie moderner Zugänge zu neuen Datenquellen. Joachim Wagner schildert das Verhältnis von Datenproduzenten und Datennutzern aus der Sicht eines unzufriedenen Datennutzers. Schließlich geht es um die Position der Statistik in der Datenwissenschaft. Ist „Data Science“ nur ein neumodisches Wort für Statistik? Ein Konzeptionspapier der Gesellschaft für Informatik (GI) hat zu Positionspapieren der DStatG und der DAGStat geführt, die von Ulrich Rendtel vorgestellt werden.
Das Kolloquium fand anlässlich der Abschiedsvorlesung von Ulrich Rendtel im Juni 2019 am Fachbereich Wirtschaftswissenschaft der Freien Universität statt.
View lessThe biological function of phytochromes is triggered by an ultrafast photoisomerization of the tetrapyrrole chromophore biliverdin between two rings denoted C and D. The mechanism by which this process induces extended structural changes of the protein is unclear. Here we report ultrafast proton-coupled photoisomerization upon excitation of the parent state (Pfr) of bacteriophytochrome Agp2. Transient deprotonation of the chromophore’s pyrrole ring D or ring C into a hydrogen-bonded water cluster, revealed by a broad continuum infrared band, is triggered by electronic excitation, coherent oscillations and the sudden electric-field change in the excited state. Subsequently, a dominant fraction of the excited population relaxes back to the Pfr state, while ~35% follows the forward reaction to the photoproduct. A combination of quantum mechanics/molecular mechanics calculations and ultrafast visible and infrared spectroscopies demonstrates how proton-coupled dynamics in the excited state of Pfr leads to a restructured hydrogen-bond environment of early Lumi-F, which is interpreted as a trigger for downstream protein structural changes.
View lessThe question how the brain distinguishes between information about self and others is of fundamental interest to both philosophy and neuroscience. In this functional magnetic resonance imaging (fMRI) study, we sought to distinguish the neural substrates of representing a full-body movement as one's movement and as someone else's movement. Participants performed a delayed match-to-sample working memory task where a retained full-body movement (displayed using point-light walkers) was arbitrarily labeled as one's own movement or as performed by someone else. By using arbitrary associations we aimed to address a limitation of previous studies, namely that our own movements are more familiar to us than movements of other people. A searchlight multivariate decoding analysis was used to test where information about types of movement and about self-association was coded. Movement specific activation patterns were found in a network of regions also involved in perceptual processing of movement stimuli, however not in early sensory regions. Information about whether a memorized movement was associated with the self or with another person was found to be coded by activity in the left middle frontal gyrus (MFG), left inferior frontal gyrus (IFG), bilateral supplementary motor area, and (at reduced threshold) in the left temporoparietal junction (TPJ). These areas are frequently reported as involved in action understanding (IFG, MFG) and domain-general self/other distinction (TPJ). Finally, in univariate analysis we found that selecting a self-associated movement for retention was related to increased activity in the ventral medial prefrontal cortex.
View lessEcological and socioeconomic impacts from biological invasions are rapidly escalating worldwide. While effective management underpins impact mitigation, such actions are often delayed, insufficient or entirely absent. Presently, management delays emanate from a lack of monetary rationale to invest at early invasion stages, which precludes effective prevention and eradication. Here, we provide such rationale by developing a conceptual model to quantify the cost of inaction, i.e., the additional expenditure due to delayed management, under varying time delays and management efficiencies. Further, we apply the model to management and damage cost data from a relatively data-rich genus (Aedes mosquitoes). Our model demonstrates that rapid management interventions following invasion drastically minimise costs. We also identify key points in time that differentiate among scenarios of timely, delayed and severely delayed management intervention. Any management action during the severely delayed phase results in substantial losses (>50% of the potential maximum loss). For Aedes spp., we estimate that the existing management delay of 55 years led to an additional total cost of approximately $ 4.57 billion (14% of the maximum cost), compared to a scenario with management action only seven years prior (< 1% of the maximum cost). Moreover, we estimate that in the absence of management action, long-term losses would have accumulated to US$ 32.31 billion, or more than seven times the observed inaction cost. These results highlight the need for more timely management of invasive alien species—either pre-invasion, or as soon as possible after detection—by demonstrating how early investments rapidly reduce long-term economic impacts.
View lessPast orbital parameters of the Moon are difficult to reconstruct from geological records because relevant data sets of tidal strata are scarce or incomplete. The sole Archean data point is from the Moodies Group (ca 3.22 Ga) of the Barberton Greenstone Belt, South Africa. From the time-series analysis of tidal bundles from a well-exposed subaqueous sand wave of this unit, Eriksson and Simpson (Geology, 28, 831) suggested that the Moon’s anomalistic month at 3.2 Ga was closer to 20 days than the present 27.5 days. This is in apparent accordance with models of orbital mechanics which place the Archean Moon in a closer orbit with a shorter period, resulting in stronger tidal action. Although this study’s detailed geological mapping and section measuring of the site confirmed that the sandstone bed in question is likely a migrating dune, the presence of angular mud clasts, channel-margin slumps, laterally aggrading channel fills and bidirectional paleocurrents in overlying and underlying beds suggests that this bedform was likely located in a nearshore channel near lower-intertidal flats and subtidal estuarine bars; it thus carries risk of incomplete preservation. Repeated measurements of foreset thicknesses along the published traverse, measured perpendicular to bedding, failed to show consistent spectral peaks. Larger data sets acquired along traverses measured parallel to bedding along the 20.5 m wide exposure are affected by minor faulting, uneven outcrop weathering, changing illumination, weather, observer bias and show a low reproducibility. The most robust measurements herein confirm the periodicity peak of approximately 14 in the original data of Eriksson and Simpson (Geology, 28, 831). Because laminae may have been eroded, the measurements may represent a lower bound of about 28 lunar days per synodic month. This estimate agrees well with Earth–Moon dynamic models which consider the conservation of angular momentum and place the Archaean Moon in a lower orbit around a faster-spinning Earth.
View lessThe late antique rabbis of Roman Palestine were seasoned jurists, experts on exegesis and legal interpretation. Yet rabbinic literature does not theorize. A positive account of rabbinic conceptions of language therefore remains a desideratum. I choose an alternative approach. Legal reasoning relies on language to ground the determinacy of the law. Jurists must thus confront language when it threatens to undermine the latter. Conversely, they may hold language to safeguard legal determinacy. Drawing on insights from legal theory, I turn to an unusual rabbinic rule of inference. Its earliest attested version suggests a universal possibility of inference “from the category of yes that of no, from the category of no that of yes.” I show that the ever-evolving uses of this rule allow us to observe a shift in linguistic attitude, increasingly acknowledging linguistic uncertainty. My findings tie in with recent advances in the study of rabbinic exegesis.
View lessDie berufliche Qualifizierung von Erwerbstätigen findet überwiegend im Rahmen der betrieblichen Weiterbildung statt. Dabei ist der Zugang zu betrieblicher Weiterbildung ungleich verteilt. Der Beitrag untersucht vor diesem Hintergrund die Teilnahme von zugewanderten Erwerbstätigen an betrieblicher Weiterbildung auf Grundlage der Daten des AES-Migra 2016 (Erhebung zum Weiterbildungsverhalten von Personen mit Migrationshintergrund). Unter Rückgriff auf bildungsökonomische und segmentationstheoretische Ansätze wird geprüft, ob ein Zusammenhang zwischen migrationsbezogenen Faktoren (Aufenthaltsstatus, Deutschkenntnisse, Herkunft/Anerkennung von Berufsabschlüssen) und der Weiterbildungsteilnahme besteht. Im Ergebnis zeigt sich, dass unter Berücksichtigung von Merkmalen des Erwerbskontextes die migrationsbezogenen Prädiktoren der Teilnahme an statistischer Bedeutung verlieren.
View lessThis paper examines the experienced well-being of employed and unemployed workers. We use the survey-adapted Day Reconstruction Method of the Innovation Sample of the German Socio-Economic Panel Study to analyze the role of the employment status for well-being, incorporating time use. We use the novel P-index to summarize the average share of pleasurable minutes on a day and show that in contrast to evaluative life satisfaction the unemployed experiences more pleasurable minutes due to the absence of working episodes. Hence, we examine working episodes in depth. While working is among the activities with the highest propensities for an unpleasant experience, it is also among the most meaningful activities. We show that meaning is a central non-monetary determinant for pleasure at work and find that pleasure during work and job satisfaction have a comparable association with meaning.
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