This study analyzes the samarium diiodide-promoted cyclizations of 5-arylpentan-2-ones to dearomatized bicyclic products utilizing density functional theory. The reaction involves a single electron transfer to the carbonyl group, which occurs synchronously with the rate determining cyclization event, and a second subsequent proton-coupled electron transfer. These redox reactions are accurately computed employing small core pseudo potentials explicitly involving all f-electrons of samarium. Comparison of the energies of the possible final products rules out thermodynamic control of the observed regio- and diastereoselectivities. Kinetic control via appropriate transition states is correctly predicted, but to obtain reasonable energy levels the influence of the co-solvent hexamethylphosphortriamide has to be estimated by using a correction term. The steric effect of the bulky samarium ligands is decisive for the observed stereoselectivity. Carbonyl groups in para-position of the aryl group change the regioselectivity of the cyclization and lead to spiro compounds. The computations suggest again kinetic control of this deviating outcome. However, the standard mechanism has to be modified and the involvement of a complex activated by two SmI2 moieties is proposed in which two electrons are transferred simultaneously to form the new C–C bond. Computation of model intermediates show the feasibility of this alternative mechanism.
Weniger anzeigenWe report electrochemical metallization (ECM) resistive switching in polycrystalline YMnO3 memristive devices using Al as an active electrode. Al/YMnO3/Pt devices exhibit bipolar resistive switching with a high ROFF/RON ratio of 104, low operational voltages of VSet ≈ 1.7 V and VReset ≈ −0.36 V and good retention properties. The resistive switching is intimately linked to the coexistence of the orthorhombic and hexagonal YMnO3 phases. The characterization of these two nanocrystalline phases is realized not only by X-ray diffraction – which is shown to be unable to reveal the presence of the orthorhombic phase – but also by a set of correlative microscopy and spectroscopy methods (scanning electron microscopy, optical microscopy, Raman spectroscopy and conductive atomic force microscopy). The origin of resistive switching is ascribed to an Al filament-based electrochemical metallization mechanism that likely occurs along an oxygen-deficient grain boundary between the hexagonal and orthorhombic nanocrystalline YMnO3 phases. The unique microstructure provided by the mixed polycrystalline phase films allows to use Al as an active electrode in YMnO3-based ECM cells, and gives perspective for further miniaturization of the devices.
Weniger anzeigenFor the transition to renewable energy sources, novel energy storage materials are more important than ever. This review addresses so-called molecular solar thermal (MOST) systems, which appear very promising since they combine light harvesting and energy storing in one-photon one-molecule processes. The focus is on norbornadiene (NBD), a particularly interesting candidate, which is converted to the strained valence isomer quadricyclane (QC) upon irradiation. The stored energy can be released on demand. The energy-releasing cycloreversion from QC to NBD can be initiated by a thermal, catalytic, or electrochemical trigger. The reversibility of the energy storage and release cycles determines the general practicality of a MOST system. In the search for derivatives, which enable large-scale applications, fundamental surface science studies help to assess the feasibility of potential substituted NBD/QC couples. We focus on investigations under well-defined ultra-high vacuum (UHV) conditions as well as experiments in liquid phase. Next to mechanistic insights into the isomerization between the two valence isomers, information on adsorption geometries, thermal stability limits, and reaction pathways of the respective molecules are discussed. Moreover, laboratory-scaled test devices demonstrated the proof of concept in various areas of application.
Weniger anzeigenChromatographic modeling software packages are valuable tools during method optimization steps. These are well established for reversed-phase applications utilizing retention time (RT) prediction to optimize separations and receive robust methods, which is of high interest for the analysis of pharmaceuticals. In contrast to liquid chromatography, the knowledge of RT prediction in supercritical fluid chromatography is limited to a manageable number of studies.
This study uses the software DryLab to predict the RTs of the peptides bacitracin (Bac), colistin, tyrothricin (Tyro), and insulin analogs. Gradient time, column temperature, and the ternary composition (terC) of carbon dioxide, methanol (MeOH), and acetonitrile (ACN) in the gradient elution are varied in a feasibility approach using a neutral (Viridis BEH) and an amino-derivatized aromatic (Torus 2-PIC) stationary phase. In the second part, chromatographic optimization is performed in silico through gradient adjustments to optimize the separation of the fingerprint of Bac. The final gradient method utilizes a Viridis BEH column (100 × 3.0 mm, 1.7 μm), carbon dioxide, and a modifier consisting of ACN/MeOH/water/methanesulfonic acid (60:40:2:0.1, v:v:v:v). In addition, changes in the retention order of Tyro compounds with the proportion of the terC in combination with a Torus Diol column are investigated.
Weniger anzeigenBackground
Overriding spinous processes, also known as ‘kissing spines’, are one of the most common causes of back pain in horses. The aim of this study was to investigate which options for diagnosis and treatment are preferred by equine orthopaedic specialists and assess which techniques are used for local injection.
Methods
An online survey was distributed among members of the European/American College of Veterinary Surgeons, the European/American College of Veterinary Sports Medicine and Rehabilitation, the International Society of Equine Locomotor Pathology and nationally recognised advanced equine orthopaedic practitioners.
Results
The survey was completed by 353 respondents. The injection techniques most commonly used involve placing two needles abaxial to the interspinous space (42%) under ultrasonographic guidance (32%) or one needle in the midline (35%) between two spinous processes. The most popular combination for overriding dorsal spinous process therapy was local injection (26.7%) combined with controlled exercise (25.5%). Manual therapy was considered by 42% of European and 25% of American specialists (p = 0.01). Surgical intervention as a first-line treatment was recommended mainly by specialists working in the United States, the UK or Ireland (p = 0.001). Overall, most equine orthopaedic veterinarians (71%; n = 201) preferred conservative management and recommended surgery only for horses that did not respond to conservative therapy.
Limitations
Respondents’ personal bias may have skewed the findings.
Conclusions
Despite a growing body of evidence, the therapeutic approach to ‘kissing spines’ in horses is influenced by professional specialisation and regional preferences. Variations in injection techniques and differing criteria for surgical intervention warrant further investigation.
Weniger anzeigenThe random greedy algorithm for finding a maximal independent set in a graph constructs a maximal independent set by inspecting the graph's vertices in a random order, adding the current vertex to the independent set if it is not adjacent to any previously added vertex. In this paper, we present a general framework for computing the asymptotic density of the random greedy independent set for sequences of (possibly random) graphs by employing a notion of local convergence. We use this framework to give straightforward proofs for results on previously studied families of graphs, like paths and binomial random graphs, and to study new ones, like random trees and sparse random planar graphs. We conclude by analysing the random greedy algorithm more closely when the base graph is a tree.
Weniger anzeigenBackground
Internet-based interventions produce comparable effectiveness rates as face-to-face therapy in treating depression. Still, more than half of patients do not respond to treatment. Machine learning (ML) methods could help to overcome these low response rates by predicting therapy outcomes on an individual level and tailoring treatment accordingly. Few studies implemented ML algorithms in internet-based depression treatment using baseline self-report data, but differing results hinder inferences on clinical practicability. This work compares algorithms using features gathered at baseline or early in treatment in their capability to predict non-response to a 6-week online program targeting depression.
Methods
Our training and test sample encompassed 1270 and 318 individuals, respectively. We trained random forest algorithms on self-report and process features gathered at baseline and after 2 weeks of treatment. Non-responders were defined as participants not fulfilling the criteria for reliable and clinically significant change on PHQ-9 post-treatment. Our benchmark models were logistic regressions trained on baseline PHQ-9 sum or PHQ-9 early change, using 100 iterations of randomly sampled 80/20 train-test-splits.
Results
Best performances were reached by our models involving early treatment characteristics (recall: 0.75–0.76; AUC: 0.71–0.77). Therapeutic alliance and early symptom change constituted the most important predictors. Models trained on baseline data were not significantly better than our benchmark.
Conclusions
Fair accuracies were only attainable by involving information from early treatment stages. In-treatment adaptation, instead of a priori selection, might constitute a more feasible approach for improving response when relying on easily accessible self-report features. Implementation trials are needed to determine clinical usefulness.
Weniger anzeigenWhile laboratory and field experiments are the major items in the toolbox of behavioral economists, household panel studies can complement them and expand their research potential. We introduce the German Socio-Economic Panel’s Innovation Sample (SOEP-IS), which offers researchers detailed panel data and the possibility to collect personalized experimental and survey data for free. We discuss what SOEP-IS can offer to behavioral economists and illustrate a set of design ideas with examples. Although we build our discussion on SOEP-IS, our purpose is to provide a guide that can be generalized to other household panel studies as well.
Weniger anzeigenEfficient monitoring of tree canopy mortality requires data that cover large areas and capture changes over time while being precise enough to detect changes at the canopy level. In the development of automated approaches, aerial images represent an under-exploited scale between high-resolution drone images and satellite data. Our aim herein was to use a deep learning model to automatically detect canopy mortality from high-resolution aerial images after severe drought events in the summers 2018–2020 in Luxembourg. We analysed canopy mortality for the years 2017–2020 using the EfficientUNet++, a state-of-the-art convolutional neural network. Training data were acquired for the years 2017 and 2019 only, in order to test the robustness of the model for years with no reference data. We found a severe increase in canopy mortality from 0.64 km2 in 2017 to 7.49 km2 in 2020, with conifers being affected at a much higher rate than broadleaf trees. The model was able to classify canopy mortality with an F1-score of 66%–71% and we found that for years without training data, we were able to transfer the model trained on other years to predict canopy mortality, if illumination conditions did not deviate severely. We conclude that aerial images hold much potential for automated regular monitoring of canopy mortality over large areas at canopy level when analysed with deep learning approaches. We consider the suggested approach a cost-efficient and -effective alternative to drone and field-based sampling.
Weniger anzeigenSituational judgment tests (SJTs) are low-fidelity simulations that are often used in personnel selection. Previous research has provided evidence that the ability to identify criteria (ATIC)—individuals' capability to detect underlying constructs in nontransparent personnel selection procedures—is relevant in simulations in personnel selection, such as assessment centers and situational interviews. Building on recent theorizing about response processes in SJTs as well as on previous empirical results, we posit that ATIC predicts SJT performance. We tested this hypothesis across two preregistered studies. In Study 1, a between-subjects planned-missingness design (N = 391 panelists) was employed and 55 selected items from five different SJTs were administered. Mixed-effects-modeling revealed a small effect for ATIC in predicting SJT responses. Results were replicated in Study 2 (N = 491 panelists), in which a complete teamwork SJT was administered with a high- or a low-stakes instruction and showed either no or a small correlation with ATIC, respectively. We compare these findings with other studies, discuss implications for our understanding of response processes in SJTs, and derive avenues for future research.
Weniger anzeigenThe Imperial Japanese Army imposed martial law (gunritsu) in areas occupied during each of the full-scale conflicts it fought between 1894 and 1945. This article traces changes and continuities in the purpose, function, and content of martial law during the First Sino-Japanese War, the Russo-Japanese War, and the Asia-Pacific War to advance our historical knowledge of a much-understudied aspect of Japanese warfare. In so doing, it details the development and evolution of martial law as an instrument of military power showing how regulations were also influenced by and, therefore, tended to reflect the different wartime priorities and macro-level policies of the (military) leadership. It also highlights that the character of martial law remained largely unchanged and reveals that many of the legal practices utilized during the Asia-Pacific War were rooted in earlier conflicts. It ultimately argues, however, that wartime context and immediate military objectives took precedence over any longer-term political ambitions in Asia and, more crucially, over the welfare of civilians under occupation.
Weniger anzeigenThe ongoing growth of cities due to better job opportunities is leading to increased labour-related commuter flows in several countries. On the one hand, an increasing number of people commute and move to the cities, but on the other hand, the labour market indicates higher unemployment rates in urban areas than in the surrounding areas. We investigate this phenomenon on regional level by an alternative definition of unemployment rates in which commuting behaviour is integrated. We combine data from the Labour Force Survey with dynamic mobile network data by small area models for the federal state North Rhine-Westphalia in Germany. From a methodical perspective, we use a transformed Fay–Herriot model with bias correction for the estimation of unemployment rates and propose a parametric bootstrap for the mean squared error estimation that includes the bias correction. The performance of the proposed methodology is evaluated in a case study based on official data and in model-based simulations. The results in the application show that unemployment rates (adjusted by commuters) in German cities are lower than traditional official unemployment rates indicate.
Weniger anzeigenCreative processes within and across organizations have not only been associated with freedom but also with constraints. By taking a dialectical process perspective, we examine how creatives actually engage with constraints and how constraints thereby emerge, unfold and terminate over time. Based on ethnographic observations and interviews with popular music songwriting teams, we found that collaborators do not simply experience but also actively utilize constraints. Doing so enables songwriters to process constraints and to organize for an oscillation between stable, generative, and flexible constraint characterizations, fueling the creative process. Notwithstanding the persistent nature of some structural constraints, these findings contribute to research on organizing creativity by conceptualizing constraints as intertwined, malleable and even transformable by actors as they unfold. Thereby, the findings extend the current understanding of creativity with constraints by pointing to the crucial role of certain constraint characterizations that need to alternate procedurally between stability and fluidity.
Weniger anzeigenIn this article we report evidence from a series of semi-structured interviews with a broad sample of people living in Denmark (n = 21), about their perspectives on the future during the first months of the global Covid-19 pandemic. The thematic and discursive analyses, based on an abductive ontology, illustrate imaginings of the future along two vectors: individual to collective and descriptive to moral. On a descriptive and individual level, people imagined getting through the pandemic on a myopic day-by-day basis; on a descriptive and collective level, people imagined changes to work and socializing. Their future was bound and curtailed by their immediate present. On a moral and individual level, respondents were less detailed in their reports, but some vowed to change their behaviors. On a moral and collective level, respondents reported what the world should be like and discussed changes to environmental behaviors such as traveling, commuting, and work. The model suggests the domain of individual moral imaginings is the most difficult domain for people to imagine beyond the practicalities of their everyday lives. The implications of this model for comprehending imaginations of the future are discussed.
Weniger anzeigenFusion crusts form during the atmospheric entry heating of meteorites and preserve a record of the conditions that occurred during deceleration in the atmosphere. The fusion crust of the Winchcombe meteorite closely resembles that of other stony meteorites, and in particular CM2 chondrites, since it is dominated by olivine phenocrysts set in a glassy mesostasis with magnetite, and is highly vesicular. Dehydration cracks are unusually abundant in Winchcombe. Failure of this weak layer is an additional ablation mechanism to produce large numbers of particles during deceleration, consistent with the observation of pulses of plasma in videos of the Winchcombe fireball. Calving events might provide an observable phenomenon related to meteorites that are particularly susceptible to dehydration. Oscillatory zoning is observed within olivine phenocrysts in the fusion crust, in contrast to other meteorites, perhaps owing to temperature fluctuations resulting from calving events. Magnetite monolayers are found in the crust, and have also not been previously reported, and form discontinuous strata. These features grade into magnetite rims formed on the external surface of the crust and suggest the trapping of surface magnetite by collapse of melt. Magnetite monolayers may be a feature of meteorites that undergo significant degassing. Silicate warts with dendritic textures were observed and are suggested to be droplets ablated from another stone in the shower. They, therefore, represent the first evidence for intershower transfer of ablation materials and are consistent with the other evidence in the Winchcombe meteorite for unusually intense gas loss and ablation, despite its low entry velocity.
Weniger anzeigenThe educational disadvantages of migrant students are a persistent problem in many Western countries. Against this background, policymakers often call for more diversity in the teacher workforce, arguing that migrant students might benefit from being taught by migrant teachers. Despite the popularity of this claim, there is almost no research-based rationale for increasing the diversity of teachers in Europe. This paper is a step toward filling this research gap for Germany, aiming to assess whether migrant teachers reduce ethnic educational disadvantages. Our analyses are based on a nationally representative large-scale assessment of ninth graders that provides information on the migration status of both students and teachers, with achievement tests and teacher-assigned grades in German as dependent variables. The results run contrary to widely held expectations, indicating little evidence that migrant students benefit from being taught by migrant teachers.
Weniger anzeigenTwo-dimensional polymeric networks are a new class of polymers with interesting physicochemical and biological properties. They promise a wide range of future biomedical applications including pathogen interactions, drug delivery, bioimaging, photothermal, and photodynamic therapy, owing to their unique features, such as high surface area and multivalent interactions at nano-biointerfaces. In this work, a thermosensitive two-dimensional polymeric network consisting poly(N-isopropylacrylamide) (pNIPAM) chains that are mechanically interlocked by a polyglycerol platform was synthesized and used for bacteria incapacitation. Two-dimensional hyperbranched polyglycerol (2D-hPG) was synthesized by a graphene-assisted strategy and used for encapsulation of azobisisobutyronitrile (AIBN). Radical polymerization of N-isopropylacrylamide by encapsulated AIBN resulted in thermoresponsive platforms with ~ 500 nm lateral size and 20–50 nm thickness. Due to its porous structure, 2D-PNPG was able to efficiently load antibiotics, such as tetracycline (TC) and amoxicillin (AMX). The rate of release of antibiotics from 2D-PNPG and the antibacterial activity of the system correlated with the variation of temperature as a result of the thermosensitivity of 2D-PNPG. This study shows that two-dimensional polymers are efficient platforms for future biomedical applications including drug delivery and bacteria incapacitation.
Weniger anzeigenThis paper presents a case study of German ‘Nazi internationalism’ as part of a broader, transnational counter-reaction to liberal and communist internationalism in the 1930s. It offers an analysis of the activities and main ideas of the Nationalist International (Internationale Arbeitsgemeinschaft der Nationalisten; IAdN), headed by the German jurist Hans Keller and active from 1934 to 1941. The IAdN promoted concepts such as Volk nationalism and a Third Europe as a solution to the European crisis, and attempted to establish an alternative law of nations to replace the post-1919 liberal order. The IAdN illustrates an early attempt to reconcile völkisch ideas with international cooperation, thus foreshadowing ‘ethno-pluralist’ concepts of the New Right in the post-war period.
Weniger anzeigenSemitic loanwords and transcriptions of longer phrases are considered in Greek inscriptions from Judaea-Palestine. Complementing recent studies in neighboring parts of the Near East, on Syria, Phoenicia, and Arabia, select examples illustrate how local languages, Hebrew and Aramaic, survived the rise of Greek to epigraphic dominance in a partially assimilated form in loanwords and transcriptions. These local languages owed a debt for this role, as did Greek, to the epigraphic habit—or varieties of epigraphic culture and mode—fostered in the region particularly under Rome and resulting in a proliferation of writing in daily life. As in neighboring areas, evidence for Judaea-Palestine clusters in the religious domain but is not limited to it. A marginal or liminal status assigned to Semitic loanwords and transcriptions in recent literature should be reexamined through considerations of distribution and context, in particular, orientation towards a real or imagined community as audience.
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