Scrolling through a social media newsfeed has become almost ubiquitous. Yet, it remains unknown what specific post elements people pay attention to and whether this varies depending on how they access social media newsfeeds. In an eye-tracking experiment among university students (N = 201), we compare user attention to specific post elements like source, title, or picture, in a dynamic Facebook newsfeed by device (desktop vs. mobile) and smartphone usage environment (private vs. public). Significant attentional differences occur at the level of the newsfeed post elements. Users pay less attention to visual information on the mobile newsfeed and more attention to textual post elements in a public setting.
Weniger anzeigenTetrapyridyl-functionalized phosphinines were prepared and structurally characterized. The donor-functionalized aromatic phosphorus heterocycles react highly selectively and even reversibly with water. Calculations reveal P,N-cooperativity for this process, with the flanking pyridyl groups serving to kinetically enhance the formal oxidative addition process of H2O to the low-coordinate phosphorus atom via H-bonding. Subsequent tautomerization forms 1,2-dihydrophosphinine derivatives, which can be quantitatively converted back to the phosphinine by applying vacuum, even at room temperature. This process can be repeated numerous times, without any sign of decomposition of the phosphinine. In the presence of CuI·SMe2, dimeric species of the type ([Cu2I2(phosphinine)]2) are formed, in which each phosphorus atom shows the less common μ2-bridging 2e−-lone-pair-donation to two Cu(I)-centres. Our results demonstrate that fully unsaturated phosphorus heterocycles, containing reactive P[double bond, length as m-dash]C double bonds, are interesting candidates for the activation of E–H bonds, while the aromaticity of such compounds plays an appreciable role in the reversibility of the reaction, supported by NICS calculations.
Weniger anzeigenCompounds containing Mn–O bonds are of utmost importance in biological systems and catalytic processes. Nevertheless, mononuclear manganese complexes containing all O-donor ligands are still rare. Taking advantage of the low tendency of the pentafluoroorthotellurate ligand (teflate, OTeF5) to bridge metal centers, we have synthesized two homoleptic manganese complexes with monomeric structures and an all O-donor coordination sphere. The tetrahedrally distorted MnII anion, [Mn(OTeF5)4]2−, can be described as a high spin d5 complex (S = 5/2), as found experimentally (magnetic susceptibility measurements and EPR spectroscopy) and using theoretical calculations (DFT and CASSCF/NEVPT2). The high spin d4 electronic configuration (S = 2) of the MnIII anion, [Mn(OTeF5)5]2−, was also determined experimentally and theoretically, and a square pyramidal geometry was found to be the most stable one for this complex. Finally, the bonding situation in both complexes was investigated by means of the Interacting Quantum Atoms (IQA) methodology and compared to that of hypothetical mononuclear fluoromanganates. Within each pair of [MnXn]2− (n = 4, 5) species (X = OTeF5, F), the Mn–X interaction is found to be comparable, therefore proving that the similar electronic properties of the teflate and the fluoride are also responsible for the stabilization of these unique species.
Weniger anzeigenO-glycosylation is a common post-translational modification that is essential for the defensive properties of mucus barriers. Incomplete and altered O-glycosylation is often linked to severe diseases, such as cancer, cystic fibrosis, and chronic obstructive pulmonary disease. Originating from a nontemplate-driven biosynthesis, mucin-type O-glycan structures are very complex. They are often present as heterogeneous mixtures containing multiple isomers. Therefore, the analysis of complex O-glycan mixtures usually requires hyphenation of orthogonal techniques such as liquid chromatography (LC), ion mobility spectrometry, and mass spectrometry (MS). However, MS-based techniques are mainly qualitative. Moreover, LC separation of O-glycans often lacks reproducibility and requires sophisticated data treatment and analysis. Here we present a mucin-type O-glycomics analysis workflow that utilizes hydrophilic interaction liquid chromatography for separation and fluorescence labeling for detection and quantification. In combination with mass spectrometry, a detailed analysis on the relative abundance of specific mucin-type O-glycan compositions and features, such as fucose, sialic acids, and sulfates, is performed. Furthermore, the average number of monosaccharide units of O-glycans in different samples was determined. To demonstrate universal applicability, the method was tested on mucins from different tissue types and mammals, such as bovine submaxillary mucins, porcine gastric mucins, and human milk mucins. To account for day-to-day retention time shifts in O-glycan separations and increase the comparability between different instruments and laboratories, we included fluorescently labeled dextran ladders in our workflow. In addition, we set up a library of glucose unit values for all identified O-glycans, which can be used to simplify the identification process of glycans in future analyses.
Weniger anzeigenThe perfluorinated silylphosphinidene, F3SiP, in the triplet ground state is generated by the reaction of laser-ablated silicon atoms with PF3 in solid neon and argon matrices. The reactions proceed with the initial formation of a silicon trifluorophosphine complex, F3PSi, in the triplet ground state, and a more stable inserted phosphasilene, FPSiF2, in the singlet ground state upon deposition. The trifluorosilylphosphinidene was formed through F-migration reactions of FPSiF2 and F3PSi following a two-state mechanism under irradiation with visible light (λ = 470 nm) and full arc light (λ > 220 nm), respectively. High-level quantum-chemical methods support the identification of F3PSi, FPSiF2, and F3SiP by matrix-isolation IR spectroscopy.
Weniger anzeigenIn this article Cristoph Wulf examines the basic concepts of pedagogy and educational science in the German-speaking world, looking at education and socialization from the perspective of educational anthropology. He makes evident that the complex German concept of Bildung, in particular, can only be fully understood by means of a historical and philosophical analysis.
Polar surfaces in water typically repel each other at close separations, even if they are charge-neutral. This so-called hydration repulsion balances the van der Waals attraction and gives rise to a stable nanometric water layer between the polar surfaces. The resulting hydration water layer is crucial for the properties of concentrated suspensions of lipid membranes and hydrophilic particles in biology and technology, but its origin is unclear. It has been suggested that surface-induced molecular water structuring is responsible for the hydration repulsion, but a quantitative proof of this water-structuring hypothesis is missing. To gain an understanding of the mechanism causing hydration repulsion, we perform molecular simulations of different planar polar surfaces in water. Our simulated hydration forces between phospholipid bilayers agree perfectly with experiments, validating the simulation model and methods. For the comparison with theory, it is important to split the simulated total surface interaction force into a direct contribution from surface–surface molecular interactions and an indirect water-mediated contribution. We find the indirect hydration force and the structural water-ordering profiles from the simulations to be in perfect agreement with the predictions from theoretical models that account for the surface-induced water ordering, which strongly supports the water-structuring hypothesis for the hydration force. However, the comparison between the simulations for polar surfaces with different headgroup architectures reveals significantly different decay lengths of the indirect water-mediated hydration-force, which for laterally homogeneous water structuring would imply different bulk-water properties. We conclude that laterally inhomogeneous water ordering, induced by laterally inhomogeneous surface structures, shapes the hydration repulsion between polar surfaces in a decisive manner. Thus, the indirect water-mediated part of the hydration repulsion is caused by surface-induced water structuring but is surface-specific and thus nonuniversal.
Weniger anzeigenWe study the application of a tailored quasi-Monte Carlo (QMC) method to a class of optimal control problems subject to parabolic partial differential equation (PDE) constraints under uncertainty: the state in our setting is the solution of a parabolic PDE with a random thermal diffusion coefficient, steered by a control function. To account for the presence of uncertainty in the optimal control problem, the objective function is composed with a risk measure. We focus on two risk measures, both involving high-dimensional integrals over the stochastic variables: the expected value and the (nonlinear) entropic risk measure. The high-dimensional integrals are computed numerically using specially designed QMC methods and, under moderate assumptions on the input random field, the error rate is shown to be essentially linear, independently of the stochastic dimension of the problem—and thereby superior to ordinary Monte Carlo methods. Numerical results demonstrate the effectiveness of our method.
Weniger anzeigenEnergy is a central concept across the sciences and an important goal of science education is to support all students so that they develop a full understanding of the energy concept. However, given the abstract and complex nature of the energy concept, only a few students develop an understanding so that they can use energy ideas to make sense of phenomena. Research into energy learning progressions aims at developing models of learning about energy to guide instruction so that students can be best supported in developing competence and has provided a rich model of how students' understanding of energy develops over time. Being largely based on cross-section data, however, the extent to which this model can guide instruction is limited, especially concerning the continued learning of students about energy. To address this gap—the limited evidence regarding what supports students' continued learning about energy—it was investigated how holding non-normative ideas and the integratedness of students' energy knowledge affect students' continued learning about energy. Drawing on data from a 4-year longitudinal study covering Grades 6–9 on students' learning about energy, diagnostic classification models were used to characterize students' non-normative idea profiles and the integratedness of their knowledge and then related both to their continued learning. The results suggest no detrimental effects of holding non-normative ideas and strong positive effects of holding integrated knowledge for students' continued learning about energy. Implications for teaching and future research are discussed.
Weniger anzeigenTuning the optoelectronic properties of monolayer MoS2 (1L-MoS2) is highly desired for optoelectronic applications. Gaining profound insights into the fundamental mechanisms that govern optoelectronic properties is of utmost significance. Here, we demonstrate that the photoluminescence (PL) of 1L-MoS2 can be modulated by photochemically functionalized graphene (F-G), which is covalently modified by oligophenyl groups. More importantly, the layer stacking sequence of F-G and 1L-MoS2 brings different interface structures, resulting in a significant difference in the PL enhancement. MoS2 supported by F-G (F-G/MoS2) has a 5-fold PL enhancement, while it only shows a 1.8-fold PL enhancement if stacked underneath F-G (MoS2/F-G). Accordingly, the results indicate that the oligophenyl groups in F-G/MoS2 not only have a p-doping effect on MoS2 but also largely prevent electron donation from the graphene basal plane with an enlarged interlayer distance of 8 nm. Consequently, the PL enhancement is lost with the thermal defunctionalization of F-G. Thus, we conclude that the functional groups can be considered as separate molecular components with the vertical arrangement in the functionalized heterostructure system. The photoactive graphene acts as a template for perpendicular molecular alignment in the heterointerface construction. The F-G/MoS2 heterostructures bring new perspectives to the design and investigation of optoelectronic devices.
Weniger anzeigenNaturally acquired immunity to the different types of malaria in humans occurs in areas of endemic transmission and results in asymptomatic infection of peripheral blood. The current study examined the possibility of naturally acquired immunity in Bornean orangutans, Pongo pygmaeus, exposed to endemic Plasmodium pitheci malaria. A total of 2140 peripheral blood samples were collected between January 2017 and December 2022 from a cohort of 135 orangutans housed at a natural forested Rescue and Rehabilitation Centre in West Kalimantan, Indonesia. Each individual was observed for an average of 4.3 years during the study period. Blood samples were examined by microscopy and polymerase chain reaction for the presence of plasmodial parasites. Infection rates and parasitaemia levels were measured among age groups and all 20 documented clinical malaria cases were reviewed to estimate the incidence of illness and risk ratios among age groups. A case group of all 17 individuals that had experienced clinical malaria and a control group of 34 individuals having an event of >2000 parasites μL−1 blood but with no outward or clinical sign of illness were studied. Immature orangutans had higher-grade and more frequent parasitaemia events, but mature individuals were more likely to suffer from clinical malaria than juveniles. The case orangutans having patent clinical malaria were 256 times more likely to have had no parasitaemia event in the prior year relative to asymptomatic control orangutans. The findings are consistent with rapidly acquired immunity to P. pitheci illness among orangutans that wanes without re-exposure to the pathogen.
Weniger anzeigenThe remains of black henbane (Hyoscyamus niger) are relatively common at archaeological sites as it grows naturally around settlements in north-western Europe. All parts of the plant may be used as a medicine or a narcotic but its natural prevalence in built environments makes it difficult to interpret any intentionality behind its presence in the archaeological record. Evidence of the deliberate collection and use of black henbane seeds in the Roman Netherlands is presented here for the first time. Examination of Classical texts and interrogation of the archaeobotanical data allow the authors to place the discovery at Houten-Castellum of a hollowed bone containing hundreds of black henbane seeds within the context of the wider Roman understanding of the plant and its properties.
Weniger anzeigenContemporary capitalist societies use different institutions to manage economic risks. While different public welfare state and financial institutions (banks, capital markets) have been studied across coordinated and liberal market economies, the different worlds of private insurance institutions have been understudied. Building on new insurance data sets (1880–2017), we find that countries with a Maritime (USA, GBR, CAN) in contrast to the more backward Alpine (AUT, DEU, CHE) insurance tradition developed bigger life and nonlife insurance earlier, with less state-associated and reinsurance enterprises, but riskier investments steered toward financial markets. We argue that the larger and more “Maritime” the insurance sector, the more it made welfare states liberal and securities markets large. Insurance is thus a hidden factor for countries’ varieties of capitalism and worlds of welfare. The recent convergence on the Maritime model, however, implies that the riskier and risk-individualizing type of private insurance has added to privatization and securitization trends everywhere.
Weniger anzeigenThe business case constitutes an important instrumental motive for corporate social responsibility (CSR), but its relationship with other moral and relational motives remains controversial. In this article, we examine the articulation of motives for CSR among different stakeholders in Germany historically. On the basis of reports of German business associations, state agencies, unions, and nongovernmental organizations from 1970 to 2014, we show how the business case came to be a dominant motive for CSR by acting as a coalition magnet: the vocabulary was used strategically by key policy entrepreneurs, while being ambiguous for flexible interpretations by different stakeholders, and thereby growing in attractiveness. As a resulting discourse coalition emerged among business, state, and civil society actors, the moral and relational motives for CSR became increasingly marginalized. The article offers a new approach to studying motives and contributes to understanding the complementary or competing nature of different motives for CSR.
Weniger anzeigenEarly investigations of subjective well-being responses to the COVID-19 pandemic indicated average deterioration but also high variability related to vulnerability of population groups and pandemic phase. Thus, we aimed to gain new insights into the characteristics of certain groups and their differences in subjective well-being response patterns over time. First, we performed Latent Class Analyses with baseline survey data of 2,137 adults (mean age = 40.98, SD = 13.62) derived from the German CORONA HEALTH APP Study to identify subgroups showing similarity of a comprehensive set of 50 risk and protective factors. Next, we investigated the course of quality of life (QoL) as an indicator of subjective well-being grouped by the identified latent classes from July 2020 to July 2021 based on monthly and pandemic phase averaged follow-up survey data by means of Linear Mixed-Effects Regression Modeling. We identified 4 latent classes with distinct indicators and QoL trajectories (resilient, recovering, delayed, chronic) similar to previous evidence on responses to stressful life events. About 2 out of 5 people showed a resilient (i.e., relative stability) or recovering pattern (i.e., approaching pre-pandemic levels) over time. Absence of depressive symptoms, distress, needs or unhealthy behaviors and presence of adaptive coping, openness, good family climate and positive social experience were indicative of a resilient response pattern during the COVID-19 pandemic. The presented results add knowledge on how to adapt and enhance preparedness to future pandemic situations or similar societal crises by promoting adaptive coping, positive thinking and solidary strategies or timely low-threshold support offers.
Weniger anzeigenThe thesis of Weak Unrestricted Composition says that every pair of objects has a fusion. This thesis has been argued by Contessa (Analysis 72(3):455–457, 2012) and Smith (Erkenntnis 84(1):41–55, 2019) to be compatible with the world being junky and hence to evade an argument against the necessity of Strong Unrestricted Composition proposed by Bohn (Analysis 69(1):27–31, 2009a, Philos Q 59(235):193–201, 2009b). However, neither Weak Unrestricted Composition alone nor the different variants of it that have been proposed in the literature can provide us with a satisfying answer to the special composition question, or so we will argue. We will then go on to explore an alternative family of purely mereological rules in the vicinity of Weak Unrestricted Composition, Cardinal Composition: A plurality of pairwise non-overlapping objects composes an object iff the objects in the plurality are of cardinality smaller than κ. As we will show, all the instances for infinite κs determine fusion and are compatible with junk, and every instance for a κ>ℵ0 is furthermore compatible with gunk and dense chains of parthood.
Weniger anzeigenMany frustrated spin models on three-dimensional (3D) lattices are currently being investigated, both experimentally and theoretically, and develop new types of long-range orders in their respective phase diagrams. They present finite-temperature phase transitions, most likely in the Heisenberg 3D universality class. However, the combination between the 3D character and frustration makes them hard to study. We present here several methods derived from high-temperature series expansions (HTSEs), which give exact coefficients directly in the thermodynamic limit up to a certain order; for several 3D lattices, supplementary orders than in previous literature are reported for the HTSEs. We introduce an interpolation method able to describe thermodynamic quantities at T>Tc, which we use here to reconstruct the magnetic susceptibility and the specific heat and to extract universal and nonuniversal quantities (for example, critical exponents, temperature, energy, entropy, and other parameters related to the phase transition). While the susceptibility associated with the order parameter is not usually known for more exotic long-range orders, the specific heat is indicative of a phase transition for any kind of symmetry breaking. We present examples of applications on ferromagnetic and antiferromagnetic models on various 3D lattices and benchmark our results whenever possible.
Weniger anzeigenAnabaena sp. PCC 7120 grows by forming filaments of communicating cells and is considered a paradigm of bacterial multicellularity. Molecular exchanges between contiguous cells in the filament take place through multiprotein channels that traverse the septal peptidoglycan through nanopores connecting their cytoplasms. Besides, the septal-junction complexes contribute to strengthen the filament. In search for proteins with coiled-coil domains that could provide for cytoskeletal functions in Anabaena, we identified SepT (All2460). SepT is characteristic of the phylogenetic clade of filamentous cyanobacteria with the ability to undergo cell differentiation. SepT-GFP fusions indicate that the protein is located at the cell periphery and, conspicuously, in the intercellular septa. During cell division, the protein is found at midcell resembling the position of the divisome. The bacterial adenylate cyclase two-hybrid analysis shows SepT interactions with itself and putative elongasome (MreB, RodA), divisome (FtsW, SepF, ZipN), and septal-junction (SepJ)-related proteins. Thus, SepT appears to rely on the divisome for localization at mature intercellular septa to form part of intercellular protein complexes. Two independently obtained mutants lacking SepT showed alterations in cell size and impaired septal and peripheral peptidoglycan incorporation during cell growth and division. Notably, both mutants showed conspicuous alterations in the array of nanopores present in the intercellular peptidoglycan disks, including aberrant nanopore morphology, number, and distribution. SepT appears, therefore, to be involved in the control of peptidoglycan growth and the formation of cell-cell communication structures that are at the basis of the multicellular character of this group of cyanobacteria.
Weniger anzeigenWe give an extension of Lê’s stochastic sewing lemma. The stochastic sewing lemma proves convergence in Lm of Riemann type sums ∑[s,t]∈πAs,t for an adapted two-parameter stochastic process A, under certain conditions on the moments of As,t and of conditional expectations of As,t given Fs. Our extension replaces the conditional expectation given Fs by that given Fv for v<s, and it allows to make use of asymptotic decorrelation properties between As,t and Fv by including a singularity in (s−v). We provide three applications for which Lê’s stochastic sewing lemma seems to be insufficient. The first is to prove the convergence of Itô or Stratonovich approximations of stochastic integrals along fractional Brownian motions under low regularity assumptions. The second is to obtain new representations of local times of fractional Brownian motions via discretization. The third is to improve a regularity assumption on the diffusion coefficient of a stochastic differential equation driven by a fractional Brownian motion for pathwise uniqueness and strong existence.
Weniger anzeigenElectrically detected magnetic resonance (EDMR) is a spectroscopic technique that provides information about the physical properties of materials through the detection of variations in conductivity induced by spin-dependent processes. EDMR has been widely applied to investigate thin-film semiconductor materials in which the presence of defects can induce the current limiting processes. Conventional EDMR measurements are performed on samples with a special geometry that allows the use of a typical electron paramagnetic resonance (EPR) resonator. For such measurements, it is of utmost importance that the geometry of the sample under assessment does not influence the results of the experiment. Here, we present a single-board EPR spectrometer using a chip-integrated, voltage-controlled oscillator (VCO) array as a planar microwave source, whose geometry optimally matches that of a standard EDMR sample, and which greatly facilitates electrical interfacing to the device under assessment. The probehead combined an ultrasensitive transimpedance amplifier (TIA) with a twelve-coil array, VCO-based, single-board EPR spectrometer to permit EDMR-on-a-Chip (EDMRoC) investigations. EDMRoC measurements were performed at room temperature on a thin-film hydrogenated amorphous silicon (a-Si:H) pin solar cell under dark and forward bias conditions, and the recombination current driven by the a-Si:H dangling bonds (db) was detected. These experiments serve as a proof of concept for a new generation of small and versatile spectrometers that allow in situ and operando EDMR experiments.
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