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Modal coupling of nonlinear inviscid axisymmetric droplet shape oscillations
No full textWe investigate the nonlinear axisymmetric shape oscillations of inviscid droplets, focusing on the modal coupling between different oscillation modes. The research builds upon the geometrically exact nonlinear theory for droplet shape oscillations by Plümacher [], which allows for large deformations and superimposed initial deformations. The theory rests on the potential flow assumption and the usual momentum jump condition at the droplet surface including the surface tension. Using the unified transform method of A. S. Fokas [], the governing equations are transformed into a system of integrodifferential equations defined on a unit sphere. These equations are then solved numerically with a Galerkin method that uses spherical harmonics and exhibits overall spectral convergence. The frequency shift and the extended time spent in the prolate state within an oscillation period are analyzed for different initial deformation modes and show good agreement with existing literature. The results demonstrate that for large initial deformations, the modal coupling significantly influences the oscillation dynamics, particularly in the interaction between even and odd modes. To study modal coupling in detail, superimposed initial deformations are investigated in which a large-amplitude even mode is superimposed with various individual small-amplitude odd modes. It is shown that the initially excited large-amplitude even mode remains nearly unaffected by the superimposed small-amplitude odd modes. The initially superimposed small-amplitude odd mode, however, is altered by the large-amplitude even mode without being significantly amplified or damped. This nonlinear modal coupling is not present in single even initial deformation modes, where it is shown that an even initial deformation mode cannot excite odd modes
Guess, Learn, Repeat: Intelligent Learning System with Synthetic and Counterfactual Training in a GeoGuessr-Inspired Classification Task
No full textInstructed learning strategy use eliminates negative reactivity of immediate judgments of learning
No full textPredicting one’s own future memory during learning (immediate judgments of learning, JOLs) can reactively alter memory performance. Recent evidence shows that making JOLs is associated with changes in the spontaneous use of learning strategies and that these changes mediate negative effects of immediate JOLs on cued recall of unrelated word pairs. This study tests whether a learning strategy instruction targeted at JOL-induced changes in spontaneous learning strategy use reduces negative JOL reactivity. Two experiments (Experiment 1: N = 193, Experiment 2: N = 200) compared cued recall of related and unrelated word pairs between groups of participants who (a) provided JOLs during study, (b) provided JOLs during study and were instructed to study unrelated pairs using mental imagery (Experiment 1) or any learning strategy (Experiment 2), or (c) did not provide JOLs and did not receive a learning strategy instruction. In both experiments, making JOLs without learning strategy instructions impaired memory performance for unrelated word pairs compared to not making JOLs (negative JOL reactivity). Importantly, learning strategy instructions eliminated negative JOL reactivity. Together with findings on spontaneous learning strategy use, these results indicate that negative JOL reactivity may be due to changes in learning strategy use, aligning with theoretical accounts that attribute negative JOL reactivity to dual-task costs or changes in goals pursued during learning
Experimental Investigation of Circulating Fluidized Bed Combustion with Solid Recovered Fuel and Integrated CO₂ Capture at Megawatt Scale
No full textThe integration of refuse derived fuels such as processed waste fractions in the form of solid recovered fuel (SRF) into combustion processes offers considerable potential for decarbonizing existing fossil-based energy systems attributable to their abundancy and high biogenic content. Circulating fluidized bed (CFB) plants are, due to their high fuel flexibility, particularly suitable for substituting fossil fuels with SRF. Although the co-combustion of SRF and coal is already established in specially designed industrial CFB plants, there is still a lack of detailed scientific knowledge about the thermodynamic and hydrodynamic effects of up to 100% fuel substitution in fluidized bed plants designed for the use of fossil fuels (for example coal). In addition, changes in the energy market, with a rising share of fluctuating renewable energy production, are enhancing the demand for dynamic operation of existing plant systems. The simultaneous integration of CO₂ capture technologies is an additional important aspect of the future energy market.
The aforementioned aspects were investigated in two experimental campaigns in a 1 MWth CFB system to evaluate the potential of existing CFB systems as retrofit options. The gradual substitution of coal with 100% SRF and its influence on the hydrodynamic and thermodynamic conditions in the CFB were analyzed as first step, showing a shift of combustion to higher reactor areas as the share of volatile components in the fuel mixture increases. The positive influence of implementing the active bed material ilmenite on both, the homogenization of combustion within the CFB and the reduction of CO (up to 69%) and CH₄ (up to 95%) was confirmed in the second step. This measure provides the possibility to counteract the combustion shift identified in the first investigation step. The third step involved the investigation of oxyfuel-combustion for assessing CO₂ capture technology in CFBs. By combining an active bed material (ilmenite) with oxyfuel combustion on the 1 MWth scale for the first time, while simultaneously utilizing 100% SRF as feedstock, it was not only possible to successfully demonstrate the implementation of a CO₂ capture technology in existing CFB systems, but also to confirm the positive influence of ilmenite on the combustion process as well as the positive influence of oxyfuel combustion on hydrodynamic and thermodynamic conditions in the CFB. The four-stage research process was completed by integrating a new concept of partial flue gas recirculation, enabling repetitive load changes without hydrodynamic or thermodynamic disturbances of the CFB system. Thus, this work demonstrates the possibility of integrating existing CFB plants into the energy market of the future
Proton-selective conductance and gating of the lysosomal cation channel TMEM175
No full textThe lysosomal cation channel TMEM175 plays a key role in luminal pH homeostasis and lysosome function, with aberrant activity linked to Parkinson’s disease. Although initially described as a K + -selective channel, TMEM175 exhibits substantial H + permeability. Here, we dissect complex changes affecting human TMEM175 conductance and ionic properties of TMEM175-mediated current in response to pH shifts on the luminal side of the protein. A drop in pH from 7.4 to 4.7 on the side equivalent to the lysosomal lumen triggers a sustained increase in TMEM175-mediated inward and outward currents, which is accompanied by a transient shift in the reversal potential (E rev ) toward the theoretical equilibrium voltage for H + , yet remaining ~100 mV below the expected value even in the absence of K + . This discrepancy, along with low sensitivity of E rev to the concentration gradient for K + , supports a model in which TMEM175-mediated H + flux rapidly collapses the lysosomal pH-gradient. Molecular dynamics simulations identify H57 as a key residue on the luminal side of the open channel, which forms intra- and intersubunit salt bridges with D279 and E282. Supporting the functional importance of these interactions, the TMEM175 mutant H57Y displayed reduced H + - and K + -conductance and a reduced H + /K + selectivity in whole-cell and lysosomal electrophysiological analyses. Our findings contribute to a better understanding of TMEM175’s complex electrophysiological properties, thereby expanding the possibilities of understanding the channel’s function in lysosomal physiology and pathophysiology
Judgments of learning in the wild: Establishing ecological validity with an intelligent tutoring system in a field study
No full textPreventing the Collapse of Peer Review Requires Verification-First AI
No full textThis paper argues that AI-assisted peer review should be verification-first rather than review-mimicking. We propose truth-coupling, i.e. how tightly venue scores track latent scientific truth, as the right objective for review tools. We formalize two forces that drive a phase transition toward proxy-sovereign evaluation: verification pressure, when claims outpace verification capacity, and signal shrinkage, when real improvements become hard to separate from noise. In a minimal model that mixes occasional high-fidelity checks with frequent proxy judgment, we derive an explicit coupling law and an incentive-collapse condition under which rational effort shifts from truth-seeking to proxy optimization, even when current decisions still appear reliable. These results motivate actions for tool builders and program chairs: deploy AI as an adversarial auditor that generates auditable verification artifacts and expands effective verification bandwidth, rather than as a score predictor that amplifies claim inflation
Revised B(E2; 2_1+ → 0_1+) value in the semi-magic nucleus Pb210
No full textThe lifetime of the 2 1 + state of Pb 210 was measured in the Pb 208 ( O 18 , O 16 ) Pb 210 two-neutron transfer reaction by γ -ray spectroscopy employing the recoil-distance Doppler-shift method. The extracted absolute B ( E 2 ) ↓ value of 119 − 8 + 9 e 2 fm 4 is consistent with previously reported measurements, but with significantly improved precision. The available experimental data for the 2 1 + − 4 1 + − 6 1 + − 8 1 + multiplet are compared with shell-model calculations based on the well-established Kuo-Herling interaction. The new B ( E 2 ) ↓ value agrees well with the shell-model prediction, providing evidence that the properties of the 2 1 + and 8 1 + states of Pb 210 can be consistently described together within the nuclear shell-model framework
Ligand field tuning of photoreactivity: contrasting low‐spin and high‐spin Fe(III)‐azido complexes
No full textWe systematically investigate the electronic structure factors underpinning the distinct photochemical behaviors in a series of structurally related Fe(III)–azido complexes ( 1 ), ( 2 ), and ( 3 ), using density functional theory (DFT), time‐dependent DFT, and ab initio ligand field theory together with the angular overlap model. It had been shown in experimental studies that the ground spin state of these complexes influences the photochemical reaction pathways, specifically photoreductive and redox‐neutral ligand dissociation, and photooxidation to yield high‐valent nitrenoid species. In addition, 3 shows a unique acetato‐ligand decarboxylation channel not observed in the low‐spin analogs. In this first comparative in silico study of the three complexes, we show how the steric demands of the methylated ligand in 3 lead to a weakened equatorial ligand field resulting in a high spin ground state which in turn influences the excited state manifold. With a simple approach, wherein we explore the evolution of the electronically excited states along specific vibrational modes, we find the onset of dissociative photooxidation paths in 1 and 2 which are absent in the high‐spin species 3 . Similarly, we can rationalize why photoinduced decarboxylation is only observed in 3
Spatial influence of fault-related stress perturbations in northern Switzerland
No full textThe spatial influence of faults on the crustal stress field is a topic of ongoing debate. While faults are often known to perturb the stress field at a meter scale, their lateral influence over a few hundred meters to several kilometers remains poorly understood. To address this knowledge gap, we use a 3D geomechanical numerical model based on 3D seismic data from northern Switzerland. The model is calibrated with 45 horizontal stress magnitude data obtained from micro-hydraulic fracturing (MHF) and sleeve re-opening (SR) tests conducted in two boreholes in the Zürich Nordost (ZNO) siting region, northern Switzerland. This model with seven faults implemented as contact surfaces serves as the reference model in our study. The reference model is systematically compared to three fault-agnostic models, which share identical rock properties, model dimensions, and calibration data with the reference model, but differ in their element resolution and mechanical properties' assignment procedure. Results show that at distances <1 km from faults, differences in maximum horizontal stress orientation between models range from 3–6°, and horizontal stress magnitude differences are approximately 1–2 MPa. Beyond 1 km, these differences reduce to <1.5° and <0.5 MPa, respectively. These differences are significantly smaller than the calibration data uncertainties at ZNO, which average to ±0.7 MPa and ±3.5 MPa for the minimum horizontal and maximum horizontal stress magnitude, respectively, and ±11° for the maximum horizontal stress orientation. An important implication of our results is that, under the specific geological, mechanical, and stress conditions observed at the ZNO siting region, explicit representation of faults may not be necessary in geomechanical models predicting the stress state of rock volumes located 1 km or more from active faults. This simplification substantially reduced our model setup time from 2 months to 2 days, without compromising the reliability of stress field predictions