Learning Analytics are an academic field with promising usage scenarios for many educational domains. At the same time, learning analytics come with threats such as the amplification of historically grown inequalities. A range of general guidelines for more equity-focused learning analytics have been proposed but fail to provide sufficiently clear guidance for practitioners. With this paper, we attempt to address this theory–practice gap through domain-specific (physics education) refinement of the general guidelines We propose a process as a starting point for this domain-specific refinement that can be applied to other domains as well. Our point of departure is a domain-specific analysis of historically grown inequalities in order to identify the most relevant diversity categories and evaluation criteria. Through two focal points for normative decision-making, namely equity and bias, we analyze two edge cases and highlight where domain-specific refinement of general guidance is necessary. Our synthesis reveals a necessity to work towards domain-specific standards and regulations for bias analyses and to develop counter-measures against (intersectional) discrimination. Ultimately, this should lead to a stronger equity-focused practice in future.Weniger anzeigen
Streptococcus suis is a porcine and zoonotic pathogen in the upper respiratory tract, expressing different capsular serotypes and virulence-associated factors. Given its genomic and phenotypic diversity, the virulence potential of S. suis cannot be attributed to a single factor. Since strong inflammatory response is a hallmark of S. suis infection, the objective of this study was to investigate the differences in transcriptional host responses to two serotype 2 and one serotype 9 strains. Both serotypes are frequently found in clinical isolates. We infected porcine precision-cut lung slices (PCLSs) with two serotype 2 strains of high (strain S10) and low (strain T15) virulence, and a serotype 9 strain 8067 of moderate virulence. We observed higher expression of inflammation-related genes during early infection with strains T15 and 8067, in contrast to infection with strain 10, whose expression peaked late. In addition, bacterial gene expression from infected PCLSs revealed differences, mainly of metabolism-related and certain virulence-associated bacterial genes amongst these strains. We conclude that the strain- and time-dependent induction of genes involved in innate immune response might reflect clinical outcomes of infection in vivo, implying rapid control of infection with less virulent strains compared to the highly virulent strain S10.Weniger anzeigen
Through a series of fortuitous events, Ian Hodder agreed to visit the Institut für Vorderasiatische Archäologie (Institute of Western Asian Archaeology), Freie Universität Berlin in early December 2013 to discuss his recent book, Entangled: An Archaeology of the Relationships between Humans and Things. A group of interested students and scholars assembled for this occasion. As organizers of this event, we are pleased to acknowledge the sponsorship of the Excellence Cluster Topoi and the Institut für Vorderasiastische Archäologie, both of the Freie Universität Berlin, and Forum Kritische Archäologie. Above all we wish to express our thanks to Ian Hodder for his willingness to engage over the course of a long afternoon with our comments and question.Weniger anzeigen
Der Begriff ‚Living History‘, im Deutschen oft als lebendige/wiederbelebte/erlebte Geschichte übersetzt, steht sowohl für populäre Geschichtsrepräsentationen als auch für den Versuch einer emotionalen Aneignung von Vergangenheit. Im Zentrum des Beitrages stehen die ‚Zeitreisenden‘ und ihr Eintauchen in fremde Welten. Nach einer knappen Skizzierung des fachübergreifenden Forschungsfelds schließen sich einige terminologische Bemerkungen bezüglich des Begriffs ‚Living History‘ an. In einem dritten Teil wird dann die Frage verfolgt, mit welchen Mitteln die Akteure meinen, den ‚Zeitsprung‘ herstellen zu können und was sie motiviert, sich aus unserer Zeit in eine andere zu begeben. Die Analyse verdeutlicht, dass die Zeitreise ein kulturelles Konstrukt ist und als karnevaleskes Abenteuer verstanden werden kann. Zuletzt wird das Potential der ‚Living History‘ als Forschungsgegenstand der Prähistorischen Archäologie beleuchtet.Weniger anzeigen
Natürliche zyklische Vorgänge, d.h. astronomische Zyklen wie der Sonnentag, der Mondmonat oder das Sonnenjahr oder physiologische Zyklen wie der circadiane Rhythmus oder der Menstruationszyklus, werden oft verwendet, um in archäologischen Funden und Befunden eingebettete Zeitinformation aufzudecken. Die Deutung bestimmter prähistorischer Artefakte als Kalendarien stellt hierfür ein wichtiges Beispiel dar. Neben einer Bevorzugung physiologischer Rhythmen als Analogien für das Paläo- und Neolithikum und astronomischer Rhythmen für die Bronzezeit fällt auf, daß in der Archäologie oft nur nach auffallenden Zahlen wie 29 oder 30 gesucht wird, ohne Hinweise für die Wiederkehr dieser Zählungen in den Artefakten zu liefern. Siedlungsstratigraphien, das zweite Beispiel, können ebenfalls als Resultate zugrundeliegender natürlicher Zyklen wie dem Jahr, Generationenwechseln oder Regenerationszyklen von Bauholz gedeutet werden. Während Ansätze, die nur die reine Tiefe der Ablagerungen heranziehen, sehr unzuverlässig sind, erlauben wiederholte Ablagerungen ähnlicher Befunde wie Fußböden oder Häuser mit bekannter Zeitdauer die Interpretation von Stratigraphien in Analogie zu natürlichen Rhythmit-Sedimenten wie den Warven. In beiden Beispielen muß jedoch beachtet werden, daß alle Zeiteinheiten wie der Monat oder das Landwirtschaftsjahr menschliche Konstrukte sind, die an die natürlichen Zyklen nur angelehnt sind, und daß auch völlig künstliche Zyklen wie die Woche existieren.Weniger anzeigen
Cell division through mitosis (microscopically visible as mitotic figures, MFs) is a highly regulated process. However, neoplastic cells may exhibit errors in chromosome segregation (microscopically visible as atypical mitotic figures, AMFs) resulting in aberrant chromosome structures. AMFs have been shown to be of prognostic relevance for some neoplasms in humans but not in animals. In this study, the prognostic relevance of AMFs was evaluated for canine cutaneous mast cell tumors (ccMCT). Histological examination was conducted by one pathologist in whole slide images of 96 cases of ccMCT with a known survival time. Tumor-related death occurred in 11/18 high-grade and 2/78 low-grade cases (2011 two-tier system). The area under the curve (AUC) was 0.859 for the AMF count and 0.880 for the AMF to MF ratio with regard to tumor-related mortality. In comparison, the AUC for the mitotic count was 0.885. Based on our data, a prognostically meaningful threshold of ≥3 per 2.37 mm2 for the AMF count (sensitivity: 76.9%, specificity: 98.8%) and >7.5% for the AMF:MF ratio (sensitivity: 76.9%, specificity: 100%) is suggested. While the mitotic count of ≥ 6 resulted in six false positive cases, these could be eliminated when combined with the AMF to MF ratio. In conclusion, the results of this study suggests that AMF enumeration is a prognostically valuable test, particularly due to its high specificity with regard to tumor-related mortality. Additional validation and reproducibility studies are needed to further evaluate AMFs as a prognostic criterion for ccMCT and other tumor types.Weniger anzeigen
Mammalian developmental timing is adjustable in vivo by preserving pre-implantation embryos in a dormant state called diapause. Inhibition of the growth regulator mTOR (mTORi) pauses mouse development in vitro, yet how embryonic dormancy is maintained is not known. Here we show that mouse embryos in diapause are sustained by using lipids as primary energy source. In vitro, supplementation of embryos with the metabolite l-carnitine balances lipid consumption, puts the embryos in deeper dormancy and boosts embryo longevity. We identify FOXO1 as an essential regulator of the energy balance in dormant embryos and propose, through meta-analyses of dormant cell signatures, that it may be a common regulator of dormancy across adult tissues. Our results lift a constraint on in vitro embryo survival and suggest that lipid metabolism may be a critical metabolic transition relevant for longevity and stem cell function across tissues.Weniger anzeigen
Herein we report on the formation of the adduct salts [Xe(OTeF5)(pyF)][Al(OTeF5)4] (pyF = C5F5N, C5H3F2N) by abstraction of an –OTeF5 group from Xe(OTeF5)2 with the Lewis superacid Al(OTeF5)3 and subsequent adduct formation of the generated [XeOTeF5]+ cation with fluorinated pyridines. These salts represent the first xenonium cations with the weakly coordinating [Al(OTeF5)4]− anion. The strong oxidizing property of these compounds is further assessed.Weniger anzeigen
This article investigates how the hybrid nature of right-wing alternative news media striving for journalistic legitimacy and partisan credibility plays out on source and topical diversity and balance in article content. The article draws on a sample of 1000 randomly selected articles published by 20 right-wing alternative online news media from six countries (the US, the UK, Germany, Austria, Denmark, and Sweden) from March 2019 to February 2020 (i.e., in “routine” pre-COVID-19 times). The results show that most of the alternative media outlets in the sample cover relatively broad topical spectra. More specifically, US and UK media primarily focus on politics and policy issues, whereas Scandinavian media are more heavily geared toward societal issues and crime coverage. Overall, right-wing alternative news content is characterized by a variety of partisan and non-partisan sources. However, core partisan topic areas, such as politics and mass media, are more likely to include partisan and especially right-wing sources. Often, with respect to these topics, right-wing sources are evaluated positively, and left-wing sources are evaluated negatively. Finally, right-wing and non-right-wing sources often appear in separate articles rather than in direct confrontation.Weniger anzeigen
Radical trifluoromethoxylation is an attractive approach to prepare compounds featuring the important OCF3 group, however most existing methods have focused on aromatic substrates. Here, we report novel methodologies with alkenyl substrates employing bis(trifluoromethyl)peroxide (BTMP) as a practical and comparatively atom economical trifluoromethoxylating reagent. With silyl enol ether substrates, switching reaction solvent allows for the synthesis of either α-(trifluoromethoxy)ketone products or unprecedented alkenyl-OCF3 species. Furthermore, allyl silanes have been employed as substrates for the first time, affording allyl(trifluoromethyl)ether products in good yields. In each case, the methods operate at room temperature without large excesses of the alkene substrate while, in contrast to previous radical trifluoromethoxylation reactions, no catalyst, light or other activators are required.Weniger anzeigen
We report the synthesis of a photo responsive metallo-hydrogel based on a ruthenium(II) complex as a functional cross-linker. This metal complex contains reactive 4AAMP (= 4-(acrylamidomethyl)pyridine) ligands, which can be cleaved by light-induced ligand substitution. Ru[(bpy)2(4AAMP)2] cross-links 4-arm-PEG-SH macromonomers by thia-Michael-addition to the photocleavable 4AAMP ligand for the preparation of the hydrogel. Irradiation with green light at 529 nm leads to photodegradation of the metallo-hydrogel due to the ligand dissociation, which can be adjusted by adjusting the Ru[(bpy)2(4AAMP)2] concentration. The ligand substitution forming [Ru(bpy)2(L)2]2+ (L = H2O and CH3CN) can be monitored by 1H NMR spectroscopy and UV-visible absorption. The control of degradation by light irradiation plays a significant role in modulating the elasticity and stiffness of the light sensitive metallo-hydrogel network. The photo-responsive hydrogel is a viable substrate for cell cultures.Weniger anzeigen
A neurological examination is essential for determining the localisation of neurological lesions. However, in avian species, quantitative data regarding the practicability and feasibility of neurological tests are very limited. Therefore, the aim of this study was to establish normative data for the neurological examination of clinically healthy birds of different species.
Forty-two domestic and feral pigeons (Columba livia domestica), 42 mute swans (Cygnus olor), 12 common buzzards (Buteo buteo), 24 common kestrels (Falco tinnunculus) and six northern goshawks (Accipiter gentilis) were examined. All birds underwent a predefined neurological examination. Interobserver variations between three examiners were investigated in 11 pigeons and 11 mute swans.
All postural reaction tests, except for the drop and flap reaction in mute swans, provoked a consistent response in pigeons and mute swans, whereas postural reaction tests of the legs in raptors were often not performable. Cranial nerve tests and most of the spinal reflexes revealed variable responses in all birds. The gastrocnemius reflex was not provokable in any bird. Interobserver agreement was almost perfect (Gwet's AC1 coefficient ≥0.81) for 16 of 21 parameters in the examination in pigeons and for 14 of 21 in mute swans.
The inclusion of free-ranging birds, which were not used to handling and for which limited information regarding age, history of previous diseases, etc. was available, may have influenced the results.
The normative neurological examination data provided in this study will help improve clinicians' interpretation of neurological examination results in the respective bird species.Weniger anzeigen
Natural systems are under increasing pressure by a range of anthropogenic global change factors. Pesticides represent a nearly ubiquitously occurring global change factor and have the potential to affect soil functions. Currently the use of synthetic pesticides is at an all-time high with over 400 active ingredients being utilized in the EU alone, with dozens of these pesticides occurring concurrently in soil. However, we presently do not understand the impacts of the potential interaction of multiple pesticides when applied simultaneously. Using soil collected from a local grassland, we utilize soil microcosms to examine the role of both rate of change and number of a selection of ten currently used pesticides on soil processes, including litter decomposition, water stable aggregates, aggregate size, soil pH, and EC. Additionally, we used null models to enrich our analyses to examine potential patterns caused by interactions between pesticide treatments. We find that both gradual and abrupt pesticide application have negative consequences for soil processes. Notably, pesticide number plays a significant role in affecting soil health. Null models also reveal potential synergistic behavior between pesticides which can further their consequences on soil processes. Our research highlights the complex impacts of pesticides, and the need for environmental policy to address the threats posed by pesticides.Weniger anzeigen
Biocompatible and functionalizable hydrogels have a wide range of (potential) medicinal applications. The hydrogelation process, particularly for systems with very low polymer weight percentages (<1 wt %), remains poorly understood, making it challenging to predict the self-assembly of a given molecular building block into a hydrogel. This severely hinders the rational design of self-assembled hydrogels. In this study, we demonstrate the impact of an N-terminal group on the self-assembly and rheology of the peptide hydrogel hFF03 (hydrogelating, fibril forming peptide 03) using molecular dynamics simulations, oscillatory shear rheology, and circular dichroism spectroscopy. We find that the chromophore and even its specific regioisomers have a significant influence on the microscopic structure and dynamics of the self-assembled fibril, and on the macroscopic mechanical properties. This is because the chromophore influences the possible salt bridges, which form and stabilize the fibril formation. Furthermore, we find that the solvation shell fibrils by itself cannot explain the viscoelasticity of hFF03 hydrogels. Our atomistic model of the hFF03 fibril formation enables a more rational design of these hydrogels. In particular, altering the N-terminal chromophore emerges as a design strategy to tune the mechanic properties of these self-assembled peptide hydrogels.Weniger anzeigen
Extreme storms are becoming more frequent and intense with climate change. Assessing lake ecosystem responses to extreme storms (resistance) and their capacity to recover (resilience) is critical for predicting the future of lake ecosystems in a stormier world. Here we provide a systematic, standardized, and quantitative approach for identifying critical processes shaping lake ecosystem resistance following extreme storms. We identified 576 extreme wind storms for 8 lakes in Europe and North America. We calculated the resistance and resilience of each lake’s surface water temperature and oxygen saturation following each storm. Sharp decreases and increases in epilimnetic temperature and oxygen saturation caused by extreme storms resulted in unpredictable changes in lake resilience values across lakes, with a tendency not to return to pre-storm conditions. Resistance was primarily shaped by mean annual chlorophyll a concentration and its overall relationship with other physiochemical lake and storm characteristics. We modeled variation in resistance as a function of both lake and storm conditions, and the results suggested that eutrophic lakes were consistently less resistant to extreme storms compared to oligotrophic lakes. The lakes tended to be most resistant to extreme storms when antecedent surface waters were warm and oxygen saturated, but overall resistance was highest in lakes with low mean annual concentrations of chlorophyll a and total phosphorus. Our findings suggest physiochemical responses of lakes to meteorological forcing are shaped by ecological and/or physical feedback and processes that determine trophic state, such as the influence of differences in nutrient availability and algal growth.Weniger anzeigen
Synapses play a vital role in information processing, learning, and memory formation in the brain. By emulating the behavior of biological synapses, electronic synaptic devices hold the promise of enabling high-performance, energy-efficient, and scalable neuromorphic computing. Ferroelectric memristive devices integrate the characteristics of both ferroelectric and memristive materials and present a far-reaching potential as artificial synapses. Here, it is reported on a new ferroelectric device on silicon, a field-effect memristor, consisting of an epitaxial ultrathin ferroelectric Hf0.5Zr0.5O2 film sandwiched between an epitaxial highly doped oxide semiconductor SrTiO3-δ and a top metal. Upon a low voltage of less than 2 V, the field-effect modulation in the semiconductor enables to access multiple states. The device works in a large time domain ranging from milliseconds down to tens of nanoseconds. By gradually switching the polarization by identical pulses, the ferroelectric diode devices can dynamically adjust the synaptic strength to mimic short- and long-term memory plasticity. Ionic contributions due to redox processes in the oxide semiconductor beneficially influence the device operation and retention.Weniger anzeigen
Microplastics affect soil functions depending on drought conditions. However, how their combined effect influences soil fungi and their linkages with ecosystem functions is still unknown. To address this, we used rhizosphere soil from a previous experiment in which we employed microplastic fibres addition and drought in a factorial design, and evaluated their effects on soil fungal communities. Microplastics decreased soil fungal richness under well-watered conditions, likely linked to microplastics leaching toxic substances into the soil, and microplastic effects on root fineness. Under drought, by contrast, microplastics increased pathogen and total fungal richness, likely related to microplastic positive effects on soil properties, such as water holding capacity, porosity or aggregation. Soil fungal richness was the attribute most affected by microplastics and drought. Microplastics altered the relationships between soil fungi and ecosystem functions to the point that many of them flipped from positive to negative or disappeared. The combined effect of microplastics and drought on fungal richness mitigated their individual negative effect (antagonism), suggesting that changes in soil water conditions may alter the action mode of microplastics in soil. Microplastic leaching of harmful substances can be mitigated under drought, while the improvement of soil properties by microplastics may alleviate such drought conditions.Weniger anzeigen
Multistationarity is the property of a system to exhibit two distinct equilibria (steady-states) under otherwise identical conditions, and it is a phenomenon of recognized importance for biochemical systems. Multistationarity may appear in the parameter space as a consequence of saddle-node bifurcations, which necessarily require an algebraically simple eigenvalue zero of the Jacobian, at the bifurcating equilibrium. Matrices with a simple eigenvalue zero are generic in the set of singular matrices. Thus, one would expect that in applications singular Jacobians are always with a simple eigenvalue zero. However, chemical reaction networks typically consider a fixed network structure, while the freedom rests with the various choices of kinetics. Here, we present an example of a chemical reaction network, whose Jacobian is either nonsingular or has an algebraically multiple eigenvalue zero. This in particular constitutes an obstruction to standard saddle-node bifurcations. The presented structural obstruction is based on the network structure alone, and it is independent of the value of the positive concentrations and the choice of kinetics.Weniger anzeigen
We discuss corporate tax effects on multinationals’ R&D. Theoretically, we find that a host country’s tax increase may boost local R&D expenditure: while R&D becomes deductible at a higher rate, this higher rate may not apply to all R&D returns. First, as R&D creates a public good within the MNE, some R&D returns are taxed at other countries’ tax rates. Second, some of the R&D returns are taxed at a lower IP regime tax rate. The positive tax rate effect is empirically supported by country-by-country R&D data of U.S.-owned subsidiaries for countries that have an IP regime.Weniger anzeigen
A practical and representative sampling method for microbiological examination of the slaughter process is useful for identifying abattoir-specific risk factors within the pig slaughter line. The aim of this study was to examine the suitability of an agar contact method (ACM), where the agar was homogenized before the microbiological processing, in comparison with the wet-dry double swabbing method (WDSM) for quantitative determination of total viable counts (TVC) on pig skin surfaces. In our experimental trial, pig skin pieces were artificially contaminated at 2 levels (3 log and 7 log cfu/ml) with a suspension of bacteria species commonly found on pig skin and cultivated in vitro. Within our field trial, pig carcasses were investigated at pre-chilling in an abattoir under standard processing conditions. For both sampling methods, TVC was determined, and statistical equivalence tests were calculated. Linear regression models showed the similarity of the sampling methods, with coefficient of determination (R2) > 90% and slope parameters of nearly 1 for both trials separately. Statistically significant equivalence between the 2 sampling methods was proven in both trials (with p < 0.0001 within an equivalence range of ± 0.5 log cfu/ml, respectively). The field trial revealed TVC on carcass surfaces sometimes at or below the lower detection limit for the ACM, while TVC from all carcasses were able to be determined by WDSM. Overall, low contamination levels were less reliably detectable by ACM than by WDSM. The ACM can be seen as an additional and suitable sampling procedure for pig skin and can contribute to the identification of abattoir specific risk factors for investigations of the hygienic status at process stages along the pig slaughter line.Weniger anzeigen