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36c378ea9ab53b70dae269fc885f6d3be93bcf13d5e9b525a000ebc8d37c674a
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2026-01-13T00:00:00-05:00
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Explaining the discrepancy in the Chandler period and the prediction of the changes in the Earths rotation dynamics
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arXiv:2601.07738v1 Announce Type: new Abstract: In this paper, in the first instance the attitude dynamics of the Earth is modelled based on physical principles so as to correctly predict the Chandler wobble and its features such as its period. To this end not only the steady state and dynamic gravity gradient torques were included, but also the effects of centrifugal acceleration on the deformable viscoelastic model of the planet. After validating the Chandler wobble response, the paper seeks to go beyond and predict the attitude response of the Earth not just over a few years but over much longer term. This requires modelling of the energy balance effects of the entire planet as a whole and not just the redistribution of mass and inertia but also the changes in the inertial properties. To this end simpler physical model of the energy balance process was included to demonstrate the sustained changes in the length of day response of the Earth over a long term. The over aim of the paper is to bring into focus the key physical processes responsible for the changes to the attitude dynamics of the Earth over a reasonable longer time frame. The overall responses of the attitude dynamics over, the short and medium terms are presented.
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https://arxiv.org/abs/2601.07738
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Academic Papers
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fc2222b2b1c8a73260bcc01195c3f3e5aaa93fa992a39fec41a1ccc580ce0342
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2026-01-13T00:00:00-05:00
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Learning to bin: differentiable and Bayesian optimization for multi-dimensional discriminants in high-energy physics
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arXiv:2601.07756v1 Announce Type: new Abstract: Categorizing events using discriminant observables is central to many high-energy physics analyses. Yet, bin boundaries are often chosen by hand. A simple, popular choice is to apply argmax projections of multi-class scores and equidistant binning of one-dimensional discriminants. We propose a binning optimization for signal significance directly in multi-dimensional discriminants. We use a Gaussian Mixture Model (GMM) to define flexible bin boundary shapes for multi-class scores, while in one dimension (binary classification) we move bin boundaries directly. On this binning model, we study two optimization strategies: a differentiable and a Bayesian optimization approach. We study two toy setups: a binary classification and a three-class problem with two signals and backgrounds. In the one-dimensional case, both approaches achieve similar gains in signal sensitivity compared to equidistant binnings for a given number of bins. In the multi-dimensional case, the GMM-based binning defines sensitive categories as well, with the differentiable approach performing best. We show that, in particular for limited separability of the signal processes, our approach outperforms argmax classification even with optimized binning in the one-dimensional projections. Both methods are released as lightweight Python plugins intended for straightforward integration into existing analyses.
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https://arxiv.org/abs/2601.07756
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Academic Papers
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a42503225d2bbac1e94e0c604842a3d4b9d151bab4a139704a355f204ffeeb56
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2026-01-13T00:00:00-05:00
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Optimizing Finite Structures to Suppress the Photonic Density of States
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arXiv:2601.07801v1 Announce Type: new Abstract: We propose a topology-optimization framework for optimizing finite structures of arbitrary shape by combining density-based methods with level-set approaches. We first optimize regular polygonal structures to suppress the photonic density of states and find that the best performing polygon is consistent with a tiling of space with hexagonal unit cells. We next show that introducing cavities into hexagonal structures further suppresses the photonic density of states, particularly when the cavity is also hexagonal. Such a result would find application in the design of fiber-optic cables. We then describe an approach for optimizing arbitrary x-simple or y-simple designs that can recover finite supercells of a hexagonal unit cell. Our approach can therefore discover the symmetry of photonic-crystal primitive unit cells that significantly suppress the photonic density of states for a given set of material parameters within a single optimization.
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https://arxiv.org/abs/2601.07801
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Academic Papers
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4a03560eb66489734d3f2a6dead7ce51f925da52005f89b5994394d38030e9b7
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2026-01-13T00:00:00-05:00
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Measurement-based acceleration of optical computations
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arXiv:2601.07814v1 Announce Type: new Abstract: Analog coprocessors are intensively developing nowadays with the aim to optimize energy computations of neural networks. In this work we focus on the possibility of using detection of collective oscillations in optical systems for computational purposes. We show that in a system of coupled resonators, collective oscillations can be used to implement matrix-vector multiplication. The matrix is formed by the coupling constants between the resonators, and the input vector is formed by the initial occupancies of the involved modes. The frequency of the collective oscillations is growing with the number of the involved modes, similarly to Rabi oscillations. The time needed for their detection, i.e., averaging, decreases with an increase in the input vector dimension. We discuss the limitations imposed on parallel computation in the system by restriction of the allowed optical frequency band.
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https://arxiv.org/abs/2601.07814
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Academic Papers
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f71aa7218a511f59b8931ea5232e6399438d4a6ce656611a764782c51ae68fb1
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2026-01-13T00:00:00-05:00
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A simple ghost free and caustic free mimetic scalar field dark matter model
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arXiv:2507.05290v1 Announce Type: cross Abstract: Chamseddine and Mukhanov have promoted the concept of mimetic dark matter as alternative dark matter candidate coming from gravitation. Unfortunately although being very interesting, their proposition turned out to have weakness among which ghost and caustic instabilities. In this paper I propose among the simplest ghost free and caustic free scalar field dark matter extension of their model; a proposition capable of challenging $\Lambda$CDM model or even capable of doing better.
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https://arxiv.org/abs/2507.05290
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Academic Papers
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706ddd31a5dbfdc51219f58450bc7ace261fae238153f8c00c80ed2d8c687a78
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2026-01-13T00:00:00-05:00
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Setting up the physical principles of resilience in a model of the Earth System
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arXiv:2601.05994v1 Announce Type: cross Abstract: Resilience is a property of social, ecological, social-ecological and biophysical systems. It describes the capacity of a system to cope with, adapt to and innovate in response to a changing surrounding. Given the current climate change crisis, ensuring conditions for a sustainable future for the habitability on the planet is fundamentally dependent on Earth System (ES) resilience. It is thus particularly relevant to establish a model that captures and frames resilience of the ES, most particularly in physical terms that can be influenced by human policy\footnote{See page 4 for examples of strategies}. In this work we propose that resilience can serve as a theoretical foundation when unpacking and describing metastable states of equilibrium and energy dissipation in any dynamic description of the variables that characterise the ES. Since the impact of the human activities can be suitably gauged by the planetary boundaries (PBs) and the planet's temperature is the net result of the multiple PB variables, such as $\text{CO}_2$ concentration and radiative forcing, atmospheric aerosol loading, atmospheric ozone depletion, etc, then resilience features arise once conditions to avoid an ES runaway to a state where the average temperature is much higher than the current one. Our model shows that this runaway can be prevented by the presence of metastable states and dynamic friction built out of the interaction among the PB variables once suitable conditions are satisfied. In this work these conditions are specified. As humanity moves away from Holocene conditions, we argue that resilience features arising from metastable states might be crucial for the ES to follow sustainable trajectories in the Anthropocene that prevent it run into a much hotter potential equilibrium state.
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https://arxiv.org/abs/2601.05994
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Academic Papers
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6af297ffcc3d3fdf5c907e99ff084e1fedc909ecab074b0a49072e93cb86e6d6
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2026-01-13T00:00:00-05:00
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Fluoride doping into SiO2-MgO-CaO bioactive glass nanoparticles: bioactivity, biodegradation and biocompatibility assessments
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arXiv:2601.06080v1 Announce Type: cross Abstract: In this research, for the first time, the structure, bioactivity, biodegradation and biocompatibility of SiO2-MgO-CaO glasses doped with different levels of fluoride were studied. The glassy powder samples were synthesized by a coprecipitation method followed by calcination at 500 C, where amorphicity and fluoride incorporation were verified by X-ray diffraction and Raman spectroscopy, respectively. The in vitro biomineralization and biodegradation of the samples were also investigated by electron microscopy, Raman spectroscopy and inductively coupled plasma optical emission spectrometry. These assessments revealed that there is an optimum level of fluoride doping to meet the highest bioactivity. Remarkably, the same level of incorporation presented the foremost biocompatibility with respect to osteoblast-like MG-63 human cells, as realized by the MTT assay and cell attachment studies.
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https://arxiv.org/abs/2601.06080
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Academic Papers
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a3166b4375c2c1675503ab69289647886451fe7daf4b72dafc7395002ef9900f
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2026-01-13T00:00:00-05:00
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Social Cost of Greenhouse Gases -- OPTiMEM and the Heat Conjecture(s)
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arXiv:2601.06085v1 Announce Type: cross Abstract: Despite well-meaning scenarios that propose global CO2 emissions will decline presented in every IPCC report since 1988, the trend of global CO2 increase continues without significant change. Even if any individual nation manages to flatten its emissions, what matters is the trajectory of the globe. Together the gulf between climate science and climate economics, plus the urgent need for alternative methods of estimation, provided the incentives for development of our Ocean-Heat-Content (OHC) Physics and Time Macro Economic Model (OPTiMEM) system. To link NOAA damages to climate required creating a carbon consumption model to drive a physics model of climate. How fast could carbon be burned and how much coal, oil and natural gas was reasonably available? A carbon model driving climate meant burning the carbon, and modelling how the earth heated up. We developed this using the most recent best greenhouse gas equations and production models for CO2, CH4, N2O, and halogenated gases. This developed an ocean heat content model for the globe. Each step is validated against Known carbon consumption, CO2, temperature, and ocean heat content. This allows a physics founded model of climate costs to be projected.
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https://arxiv.org/abs/2601.06085
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Academic Papers
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125aa1a89989c55197724550dd5139d6c0bf29d2a8e3fba76217547453f99c1c
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2026-01-13T00:00:00-05:00
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Confinement-controlled chase-escape dynamics
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arXiv:2601.06291v1 Announce Type: cross Abstract: We investigate a minimal chase-and-escape model on a two-dimensional square lattice with randomly distributed static obstacles, focusing on how geometric disorder controls collective pursuit dynamics. Chasers and escapers move according to short-range sensing rules, while the density of obstacles tunes the connectivity of the accessible space. Using a combination of geometric analysis, dynamical observables, survival statistics, and transport characterization, we establish a direct link between lattice connectivity and pursuit efficiency. A Breadth-First Search analysis reveals that obstacle-induced fragmentation leads to a progressive loss of accessibility before the percolation threshold, defining the effective initial conditions for the dynamics. The trapping time and capture cost exhibit a non-monotonic dependence on obstacle density, reflecting a competition between path elongation in connected environments and geometric confinement near the percolation threshold. Survival analysis shows that the decay of the escaper population follows a Weibull form, with characteristic time and shape parameters displaying clear crossovers as a function of obstacle density, signaling the coexistence of cooperative capture and confinement-dominated trapping. Transport properties, quantified through the mean-squared displacement exponent, further support this picture, revealing sub-diffusive dynamics and a convergence toward a geometry-controlled regime near percolation. Overall, our results demonstrate that chase--and--escape dynamics in disordered environments are governed by a geometry-driven crossover, where percolation and connectivity act as unifying control parameters for spatial, temporal, and collective behavior.
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https://arxiv.org/abs/2601.06291
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Academic Papers
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40600837944b1cd7bb516c5dc73c98bb2e60c7f9adae25b68fdfcd46bec79623
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2026-01-13T00:00:00-05:00
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Plane partitions and spin adapted quantum states
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arXiv:2601.06295v1 Announce Type: cross Abstract: We describe an explicit basis for the $\operatorname{SU}(2)$-invariant space of the exterior power $\wedge_{2k} \mathbb{C}^{2m}$ via the combinatorics of plane partitions. In quantum chemistry, this is the space of spin adapted quantum states of an electronic system with $m$ spin orbitals and $k$ electron pairs. We construct our basis by identifying the invariant space with an Artinian commutative ring called the excitation ring. We compute a Gr\"obner basis and enumerate its standard monomials via an explicit bijection to Dyck paths counted by the Narayana numbers.
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https://arxiv.org/abs/2601.06295
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Academic Papers
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c06e55821a49439b8879f2da5455c85148af30b8047b60114e56b14c3ea02dad
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2026-01-13T00:00:00-05:00
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Looking for Work in Quantum Thermodynamics
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arXiv:2601.06312v1 Announce Type: cross Abstract: This paper diagnoses a much-discussed problem in quantum thermodynamics, that of generalizing classical work into the quantum domain. I begin with the no-go theorem of Perarnau-Llobet et al (2017): no universal measurement scheme for quantum work satisfies two intuitive, classically consilient desiderata. I assess this incompatibility as stemming from the measurement problem. Decoherence restores compatibility for all practical purposes, but raises questions about what 'universality' should mean and whether any measurement scheme can be 'universal'. I consider a different standard of universality -- in terms of ontology -- by defining a trajectory-based notion of quantum work using the quantum potential. While this preserves the classical role of work as the integral of forces over distances, and evades the tension of the no-go theorem, consilience fails elsewhere; no single quantum work concept seems capable of preserving all classical features, raising questions for what it takes for successful generalization of the work concept to quantum thermodynamics.
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https://arxiv.org/abs/2601.06312
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Academic Papers
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0b18cef80916e19329ae1da75c43eeb3464dd3c18d73673837b8a398fc8a4de7
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2026-01-13T00:00:00-05:00
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On Causality and Predictivity
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arXiv:2601.06346v1 Announce Type: cross Abstract: Certain approaches to quantum gravity, such as the one based on the concept of purely virtual particles (fakeons), sacrifice the cause-effect relation at very small scales to reconcile renormalizability with unitarity. Other developments have also urged caution regarding the idea of causality as a fundamental principle. In this paper, we examine the problem from multiple perspectives, including locality and predictivity, and extend the existing skepticism in several directions. Emphasizing the impact of unruly "disruptors", we point out that the illusory arrow of time associated with causality and predictivity is inherently statistical. This renders the cause-effect relation strained at the microscopic level. We also show that causation is a borderline concept that demands belief in entities which can act on nature without being part of it. Ultimately, not only is renouncing microcausality a reasonable price to pay for a consistent and predictive theory of quantum gravity (as is the one based on the fakeon idea), but the very notion of causality is misleading. Resting as it does on metaphysical assumptions, it should therefore be abandoned in fundamental physics.
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https://arxiv.org/abs/2601.06346
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Academic Papers
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0b1f3e4e7203f0e148239d7a412dff7edb98468294cabd657f16589ba5b53cfe
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2026-01-13T00:00:00-05:00
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Effect of substrate mismatch, orientation, and flexibility on heterogeneous ice nucleation
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arXiv:2601.06510v1 Announce Type: cross Abstract: Heterogeneous nucleation is the main path to ice formation on Earth. The ice nucleating ability of a certain substrate is mainly determined by both molecular interactions and the structural mismatch between the ice and the substrate lattices. We focus on the latter factor using molecular simulations of the mW model. Quantifying the effect of structural mismatch alone is challenging due to its coupling with molecular interactions. To disentangle both factors, we use a substrate composed of water molecules in such a way that any variation on the nucleation temperature can be exclusively ascribed to the structural mismatch. We find that a one per cent increase of structural mismatch leads to a decrease of approximately 4 K in the nucleation temperature. We also analyse the effect of the orientation of the substrate with respect to the liquid. The three main ice orientations (basal, primary prism and secondary prism) have a similar ice nucleating ability. We finally asses the effect of lattice flexibility by comparing substrates where molecules are immobile with others where a certain freedom to fluctuate around the lattice positions is allowed. Interestingly, we find that the latter type of substrate is more efficient in nucleating ice because it can adapt its structure to that of ice.
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https://arxiv.org/abs/2601.06510
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Academic Papers
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2eb8a533cdf2298c394f6cb69ebe2dc67df503ee5b0fb27cb1fe3a43cce0952b
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2026-01-13T00:00:00-05:00
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Snapping and Switching of Elastic Arches with Patterned Preferred Curvature
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arXiv:2601.06598v1 Announce Type: cross Abstract: An elastic arch is an archetypal bistable system. Here, we combine elastica theory and photo-mechanical experiments to elucidate the mechanics of an active arch with a spatio-temporally varying preferred curvature $\overline \kappa(s)$. Our shallow-arch theory completely describes any such system via the decomposition of its $\overline \kappa(s)$ into Euler-buckling modes. Intuitively, if $\overline \kappa(s)$ overlaps with the fundamental mode, it snaps the arch up/down. Conversely, non-overlapping $\overline \kappa(s)$ drives a second-order transition to a higher-order shape. Furthermore, the form of $\overline \kappa(s)$ enables control over the instability's character; we find the forms for snapping with maximum energy release and at the lowest stimulation (both binary patterns) and design forms for symmetric and asymmetric switching pathways. Analogous control can also be achieved in boundary-driven instabilities of passive arches by fabricating them with suitable $\overline \kappa(s)$. We thus anticipate our results will improve switchable/snapping elements in MEMS, robotics, and mechanical meta-materials.
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https://arxiv.org/abs/2601.06598
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Academic Papers
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ce5adddb020b7e5b49e485257670c516da296ea011b95eaf8a77c4b5d24c67d9
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2026-01-13T00:00:00-05:00
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Global Well-Posedness of the Vacuum Free Boundary Problem for the Degenerate Compressible Navier-Stokes Equations With Large Data of Spherical Symmetry
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arXiv:2601.06620v1 Announce Type: cross Abstract: The study of global-in-time dynamics of vacuum is crucial for understanding viscous flows. However, the corresponding large-data problems for multidimensional spherically symmetric flows have remained open, due to the coordinate singularity at the origin and the strong degeneracy on the moving boundary. In this paper, we analyze the vacuum free boundary problem for the barotropic compressible Navier-Stokes equations with degenerate density-dependent viscosity coefficients (as in the shallow water equations) in two and three spatial dimensions. We prove that, for a general class of spherically symmetric initial density: $\rho_0^{\beta}\in H^3$ with $\beta\in (\frac{1}{3},\gamma-1]$ ($\gamma$: adiabatic exponent) vanishing on the moving boundary in the form of a distance function, no vacuum forms inside the fluid in finite time, and we establish the global well-posedness of classical solutions with large initial data. Particularly, when $\beta=\gamma-1$, the initial density contains a physical vacuum, but fails to satisfy the condition required for the Bresch-Desjardins (BD) entropy estimate when $\gamma\ge 2$. Our analysis is mainly based on a region-segmentation method: near the origin, we develop an interior BD entropy estimate, thereby obtaining flow-map-weighted estimates for the density; while, near the boundary, we construct $\rho_0$-weighted estimates for the effective velocity, which differ fundamentally from the classical BD entropy estimates and yield novel flow-map-weighted estimates for both the fluid and the effective velocities. These estimates enable us to obtain the uniform upper bound for the density and show that no cavitation occurs inside the fluid. The methodology developed here should also be useful for solving other related nonlinear equations involving similar difficulties.
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https://arxiv.org/abs/2601.06620
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Academic Papers
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45011ddfcbf45adc22a2356ed6461444f7bbe2c439fd12b4813b030c2737c3f2
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2026-01-13T00:00:00-05:00
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Electric field switching of altermagnetic spin-splitting in multiferroic skyrmions
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arXiv:2601.06738v1 Announce Type: cross Abstract: Magnetic skyrmions are localized magnetic structures that retain their shape and stability over time, thanks to their topological nature. Recent theoretical and experimental progress has laid the groundwork for understanding magnetic skyrmions characterized by negligible net magnetization and ultrafast dynamics. Notably, skyrmions emerging in materials with altermagnetism, a novel magnetic phase featuring lifted Kramers degeneracy-have remained unreported until now. In this study, we demonstrate that BiFeO3, a multiferroic renowned for its strong coupling between ferroelectricity and magnetism, can transit from a spin cycloid to a Neel-type skyrmion under antidamping spin-orbit torque at room temperature. Strikingly, the altermagnetic spin splitting within BiFeO3 skyrmion can be reversed through the application of an electric field, revealed via the Circular photogalvanic effect. This quasiparticle, which possesses a neutral topological charge, holds substantial promise for diverse applications-most notably, enabling the development of unconventional computing systems with low power consumption and magnetoelectric controllability.
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https://arxiv.org/abs/2601.06738
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Academic Papers
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f7f093dfb58adc3547778aaafcd2db95846de0235a318be60cb3e7ac0bfebafc
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2026-01-13T00:00:00-05:00
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Quantum science with arrays of metastable helium-3 atoms
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arXiv:2601.06763v1 Announce Type: cross Abstract: The motion of atoms in programmable optical tweezer arrays offers many new opportunities for neutral atom quantum science. These include inter- and intra-site atom motion for resource-efficient implementations of fermionic and bosonic modes, respectively, as well as tweezer transport for efficient compilation of arbitrary circuits. However, the exploitation of atomic motion for all three purposes and others is limited by the inertia of the atoms. We present a comprehensive architectural blueprint for the use of fermionic metastable helium-3 ($^3$He$^*$) atoms -- the lightest trappable atomic species -- in programmable optical tweezer arrays. This includes a concrete analysis of atomic structure considerations as well as Rydberg-mediated interactions. We show that inter-tweezer hopping of $^3$He$^*$ atoms can be $\gtrsim3\times$ faster than previous demonstrations with lithium-6. We also demonstrate a new toolbox for encoding and manipulating qubits directly in the tweezer trap potential, uniquely enabled by the light mass of $^3$He$^*$. Finally, we provide several examples of new opportunities for fermionic quantum simulation and computation that leverage the transport and inter-tweezer hopping of $^3$He$^*$ atom arrays. These tools present new methods to improve the resource efficiency of neutral atom quantum science that may also enable quantum simulations of lattice gauge theories and quantum chemistry outside the Born-Oppenheimer approximation
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https://arxiv.org/abs/2601.06763
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Academic Papers
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213afba8b2accc158d728c3bbe5cc229cd0372079b7526893ec06e94204e7d4b
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2026-01-13T00:00:00-05:00
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Size Dependent Ternary Halide Solid Solutions in Perovskite Nanocrystals
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arXiv:2601.06880v1 Announce Type: cross Abstract: Crystalline solid solutions incorporate guest atoms by substituting host lattice sites up to a solubility limit dictated by solute host similarity. Solid solutions enable tuning various material properties, such as the optoelectronic behavior of halide perovskites. In bulk, incompatibility of Cl:I halide mixtures restricts exploration throughout the ternary halide Cl:Br:I compositional range. However, solubility is extended in nanocrystals which better accommodate a wider range of ions within their lattice. Through high throughput synthesis and spectroscopic characterization of over 3000 samples, along with density functional theory and cluster expansion models, we determine the solubility boundaries of ternary halide perovskite nanocrystals and demonstrate their extended size dependent miscibility. Smaller nanocrystals, with sufficient Br content, stabilize the Cl:Br:I solid solutions, suppress planar stacking fault defects and prevent halide segregation.
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https://arxiv.org/abs/2601.06880
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Academic Papers
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436528231ff4ff6128a8ac086d2ddc12a2a43970c301165f9ddfe104df743ba3
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2026-01-13T00:00:00-05:00
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Essentially No Energy Barrier Between Independent Fermionic Neural Quantum State Minima
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arXiv:2601.06939v1 Announce Type: cross Abstract: Neural quantum states (NQS) have proven highly effective in representing quantum many-body wavefunctions, but their loss landscape remains poorly understood and debated. Here, we demonstrate that the NQS loss landscape is more benign and similar to conventional deep learning than previously thought, exhibiting mode connectivity: independently trained NQS are connected by paths in parameter space with essentially no energy barrier. To construct these paths, we develop GeoNEB, a path optimizer integrating efficient stochastic reconfiguration with the nudged elastic band method for constructing minimum energy paths. For the strongly interacting six-electron quantum dot modeled by a $1.6$M-parameter Psiformer, we find two independent minima with expected energy barrier $\sim10^{-5}$ times smaller than the system's overall energy scale and $\sim10^{-3}$ times smaller than the linear path's barrier. The path respects physical symmetry in addition to achieving low energy, with the angular momentum remaining well quantized throughout. Our work is the first to construct optimized paths between independently trained NQS, and it suggests that the NQS loss landscape may not be as pathological as once feared.
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https://arxiv.org/abs/2601.06939
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Academic Papers
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1a44d56a03b2393e435dbc1af052e4ddfcc0e3b7a9a5a59d36e89bf91f5d7c74
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2026-01-13T00:00:00-05:00
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Case study of an exploratory high voltage NASICON-based Na$_4$NiCr(PO$_4$)$_3$ cathode material for sodium-ion batteries
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arXiv:2601.07012v1 Announce Type: cross Abstract: We examine a new NASICON-type Na$_4$NiCr(PO$_4$)$_3$ material designed for high-voltage and multi-electron reactions for the sodium-ion batteries (SIBs). The Rietveld refinement of the X-ray diffraction pattern, using the R$\bar{3}$c space group, confirmed the stabilization of the rhombohedral NASICON framework. Furthermore, the Raman and Fourier transform infrared spectroscopy are employed to probe the structure and chemical bonding. The core-level photoemission analysis reveals the Cr$^{3+}$ and mixed Ni$^{2+}$/Ni$^{3+}$ oxidation states in the sample. Moreover, the bond valence energy landscape (BVEL) analysis, based on the refined structure, revealed a three-dimensional network of well-connected sodium sites with a migration energy barrier of 0.468 eV. The material delivered a good charge capacity at around 4.5 V, but showed no sodium-ion intercalation during discharge, resulting in negligible discharge capacity. The post-mortem analysis confirmed that the crystal structure remained intact. The calculated energy barrier values indicated a reversal in sodium site stability after cycling, though the barriers can still permit feasible ion migration. This suggests that ion transport alone cannot explain the lack of reversibility, which likely arises from intrinsically poor electronic conductivity. These findings highlight key challenges in achieving stable, reversible capacity in this system and underscore the need for doping, structural modification, and electrolyte optimization to realize its full potential as a high-voltage SIB cathode.
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https://arxiv.org/abs/2601.07012
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80b64afa65d9830f7db0817298f24ca99f20fd681877b3989fc9b232d211f590
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2026-01-13T00:00:00-05:00
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Largest connected component in duplication-divergence growing graphs with symmetric coupled divergence
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arXiv:2601.07024v1 Announce Type: cross Abstract: The largest connected component in duplication-divergence growing graphs with symmetric coupled divergence is studied. Finite-size scaling reveals a phase transition occurring at a divergence rate $\delta_c$. The $\delta_c$ found stands near the locus of zero in Euler characteristic for finite-size graphs, known to be indicative of the largest connected component transition. The role of non-interacting vertices in shaping this transition, with their presence ($d=0$) and absence ($d=1$) in duplication is also discussed, suggesting a particular transformation of the time variable considered yielding a singularity locus in the natural logarithm of Euler characteristic of finite-size graphs close to that obtained with $d=1$ but from the model with $d=0$. The findings may suggest implications for bond percolation in these growing graph models.
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https://arxiv.org/abs/2601.07024
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Academic Papers
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742ce78449761f8610c76d03b2bcbc27f5b7ee432e6b6517b25f52f74a9518ee
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2026-01-13T00:00:00-05:00
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Dynamic redundancy and mortality in stochastic search
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arXiv:2601.07096v1 Announce Type: cross Abstract: Search processes are a fundamental part of natural and artificial systems. In such settings, the number of searchers is rarely constant: new agents may be recruited while others can abandon the search. Despite the ubiquity of these dynamics, their combined influence on search efficiency remains unexplored. Here we present a general framework for stochastic search in which independent agents progressively join and leave the process, a mechanism we term \emph{dynamic redundancy and mortality} (DRM). Under minimal assumptions on the underlying search dynamics, this framework yields exact first-passage time statistics. It further reveals surprising connections to stochastic resetting, including a regime in which the resetting mean first-passage time emerges as a universal lower bound for DRM, as well as regimes in which DRM search is faster. We illustrate our results through a detailed analysis of one-dimensional Brownian DRM search. Altogether, this work provides a rigorous foundation for studying first-passage processes with a fluctuating number of searchers, with direct relevance across physical, biological, and algorithmic systems.
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https://arxiv.org/abs/2601.07096
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1d74cc6d25318581b3a16bcdc4f4ab1cd9a55436f2e4c7c2df1546a6b8d0e529
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2026-01-13T00:00:00-05:00
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Chiroptical effect induced by gravitational waves
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arXiv:2601.07179v1 Announce Type: cross Abstract: We propose the gravitational analog of the chiroptical effect for the first time, demonstrating that gravitational waves (GWs) can induce a reversal of photon chirality through the exchange of angular momentum, namely the spin-2-gravitation chiroptical effect. By analyzing the interaction between photon spin angular momentum (SAM) and GWs, we derive the selection rules governing this exchange, which are strictly dictated by the spin-1 and spin-2 nature of the electromagnetic and gravitational fields, respectively. We find that the gravitational chiroptical effect reflects the local nature of SAM which prevents the accumulation of gravitational perturbations over spatial phase windings, and offers a theoretically rigorous tool to probe the chiral structure of GWs. This mechanism provides a novel observational pathway to constrain modified gravity theories, measure the asymmetric properties of compact binaries, and explore parity-violating physics in the early universe.
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https://arxiv.org/abs/2601.07179
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cbfbeb6b59562666ea7ff96c3d0bcf5af1cd336e4f5cd7ca7c1ea6ef5e077a57
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2026-01-13T00:00:00-05:00
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Curvature-driven shifts of the Potts transition on spherical Fibonacci graphs: a graph-convolutional transfer-learning study
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arXiv:2601.07346v1 Announce Type: cross Abstract: We investigate the ferromagnetic $q$-state Potts model on spherical Fibonacci graphs. These graphs are constructed by embedding quasi-uniform sites on a sphere and defining interactions via a chord-distance cutoff chosen to yield a network approximating four-neighbor connectivity. By combining Swendsen-Wang cluster Monte Carlo simulations with graph convolutional networks (GCNs), which operate directly on the adjacency structure and node spins, we develop a unified phase-classification framework applicable to both regular planar lattices and curved, irregular spherical graphs. Benchmarks on planar lattices demonstrate an efficient transfer strategy: after a fixed binarization of Potts spins into an effective Ising variable, a single GCN pretrained on the Ising model can localize the transition region for different $q$ values without retraining. Applying this strategy to spherical graphs, we find that curvature- and defect-induced connectivity irregularities produce only modest shifts in the inferred transition temperatures relative to planar baselines. Further analysis shows that the curvature-induced shift of the critical temperature is most pronounced at small $q$ and diminishes rapidly as $q$ increases; this trend is consistent with the physical picture that, in two dimensions, the Potts model undergoes a transition from a continuous phase transition to a weakly first-order one for $q>4$, accompanied by a pronounced reduction of the correlation length.
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https://arxiv.org/abs/2601.07346
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3b9636e12d3cc3b26ca79afba8b9c3bbd9dcee732300808332ab010405feb359
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2026-01-13T00:00:00-05:00
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Janus Polymeric Giant Vesicles on Demand: A Predictive Phase Separation Approach for Efficient Formation
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arXiv:2601.07409v1 Announce Type: cross Abstract: Janus particles, with their intrinsic asymmetry, are attracting major interest in various applications, including emulsion stabilization, micro/nanomotors, imaging, and drug delivery. In this context, Janus polymersomes are particularly attractive for synthetic cell development and drug delivery systems. While they can be achieved by inducing a phase separation within their membrane, their fabrication method remains largely empirical. Here, we propose a rational approach, using Flory-Huggins theory, to predict the self-assembly of amphiphilic block copolymers into asymmetric Janus polymersomes. Our predictions are experimentally validated by forming highly stable Janus giant unilamellar vesicles (JGUVs) with a remarkable yield exceeding 90% obtained from electroformation of various biocompatible block copolymers. We also present a general phase diagram correlating mixing energy with polymersome morphology, offering a valuable tool for JGUV design. These polymersomes can be extruded to achieve quasi-monodisperse vesicles while maintaining their Janus-like morphology, paving the way for their asymmetric functionalization and use as active carriers.
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https://arxiv.org/abs/2601.07409
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b4f6cfd033b123623d6f0ceba8a43da11b51f3e1fffb03c1b2f61b3eea891723
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2026-01-13T00:00:00-05:00
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Quantum model for black holes and clocks
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arXiv:2601.07437v1 Announce Type: cross Abstract: We consider a stationary quantum system consisting of two non-interacting yet entangled subsystems, $\Xi$ and $\Gamma$. We identify a quantum theory characterizing $\Xi$ such that, in the quantum-to-classical crossover of the composite system, $\Gamma$ behaves as a test particle within the gravitational field of a Schwarzschild Black Hole (SBH) near its event horizon. We then show that this same quantum theory naturally provides a representation of $\Xi$ in terms of bosonic modes, whose features match those of the Hawking radiation; this facilitates the establishment of precise relations between the phenomenological parameters of the SBH and the microscopic details of the quantum model for $\Xi$. Finally, we recognize that the conditions used to characterize $\Gamma$ and $\Xi$ coincide with those required by the Page and Wootters mechanism for identifying an evolving system and an associated clock. This leads us to discuss how the quantum model for $\Xi$ endows the SBH with all the characteristics of a "perfect" clock.
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https://arxiv.org/abs/2601.07437
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c9bb7d7d7c3a79dddb2c6a31d046b70faf4b8ecd50f76604d210a73adb52662a
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2026-01-13T00:00:00-05:00
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Functionalization of Benzene Ices by Atomic Oxygen
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arXiv:2601.07457v1 Announce Type: cross Abstract: Small aromatic molecules, including functionalized derivatives of benzene, are known to be present throughout the different stages of star and planet formation. In particular, oxygen-bearing monosubstituted aromatics, likely including phenol, have been identified in the coma of comet 67P. This suggests that, earlier in the star and planet formation evolution, icy grains may act as both reservoirs and sites of functionalization for these small aromatics. We investigate the ice-phase reactivity of singlet oxygen atoms (O($^1$D)) with benzene, using ozone as a precursor that is readily photodissociated by relatively low-energy. Our experiments show that O($^1$D) efficiently reacts with benzene, forming phenol, benzene oxide, and oxepine as the main products. Phenol formation is temperature-independent, consistent with a barrierless insertion mechanism. In contrast, the formation of benzene oxide/oxepine shows a slight temperature dependence, suggesting that additional reaction pathways involving either ground-state or excited-state oxygen atoms may contribute. In H$_2$O and \COO ice matrices we find that dilution does not suppress formation of phenol. We extrapolate an experimental upper limit for the benzene-to-phenol conversion fraction of 27-44$\%$ during the lifetime of an interstellar cloud, assuming O($^1$D) production rates based on CO$_2$ ice abundances and a cosmic-ray induced UV field. We compare these estimates with a new analysis of data from the comet 67P, where the C$_6$H$_6$O/C$_6$H$_6$ ratio is 20$\pm$6$\%$. This value lies within our estimated range, suggesting that O($^1$D)-mediated chemistry is a viable pathway for producing oxygenated aromatics in cold astrophysical ices, potentially enriching icy planetesimals with phenol and other biorelevant compounds.
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https://arxiv.org/abs/2601.07457
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469a34fa6b24c2e0a47bd2f8bfab6ffa1345c61be98fbe3d8e8744a37dd7e03e
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2026-01-13T00:00:00-05:00
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Coupling a discrete state to a quasi-continuum: A model quantum mechanical system that interpolates between Rabi oscillations and decay-revival dynamics
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arXiv:2601.07557v1 Announce Type: cross Abstract: We formulate a quantum mechanical system consisting of a single discrete state coupled to an infinite ladder of equally-spaced states, the coupling between the two being given by a Lorentzian profile. Various limits of this system correspond to well-known models from quantum optics, namely, the narrow resonance limit gives the Rabi system, the wide resonance limit gives the Bixon-Jortner system, the wide resonance, true continuum limit gives the Wigner-Weisskopf system, and the fixed resonance, true continuum limit gives a system that is typically studied by methods developed by Fano. We give a semi-analytical solution of the eigenvalue problem by reducing it to a transcendental equation, and demonstrate the aforementioned limiting behaviors. We then study the dynamics of the initial discrete state numerically, and show that it gives a wide range of behaviors in various limiting cases as predicted by our asymptotic theory including exponential decay, revivals, Rabi oscillations, and damped oscillations. The ability of this system to interpolate between such a rich set of behaviors and existing model systems, and the accessibility of a semi-analytical solution, make it a useful model system in quantum optics and related fields.
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https://arxiv.org/abs/2601.07557
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b5f4a13a0168e81e39a829ea19ba6129564df0b6ce7fcf9881377c491c26bf6c
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2026-01-13T00:00:00-05:00
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Excitation spectrum of a bright solitary wave in a Bose-Einstein condensate and its connection with the Higgs and the Goldstone modes
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arXiv:2601.07575v1 Announce Type: cross Abstract: We consider the problem of Bose-Einstein condensed atoms, which are confined in a (quasi) one-dimensional toroidal potential. We focus on the case of an effective attractive interaction between the atoms. The formation of a localized blob (i.e., a ``bright" solitary wave) for sufficiently strong interactions provides an example of spontaneous symmetry breaking. We evaluate analytically and numerically the excitation spectrum for both cases of a homogeneous and of a localized density distribution. We identify in the excitation spectrum the emergence of the analogous to the Goldstone and the Higgs modes, evaluating various relevant observables, gaining insight into these two fundamental modes of excitation.
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https://arxiv.org/abs/2601.07575
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abe61306256873997138d1d41e223441d6ad3ec7504488e9476566f1eba76e23
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2026-01-13T00:00:00-05:00
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Speaking of Opinions: Comparing Approaches to Modelling Opinion Manipulation
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arXiv:2601.07619v1 Announce Type: cross Abstract: This review outlines the major approaches to modelling opinion formation and manipulation in mathematics and computer science. Key tools such as ordinary and partial differential equations, stochastic models, control theory, and interaction protocols are introduced and compared as methods for describing manipulation. The review is separated into those models using a continuous opinion space and those using discrete or binary opinions, with the advantages and disadvantages of each discussed. Finally, the authors provide an interdisciplinary perspective on the field of opinion dynamics and its social significance.
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https://arxiv.org/abs/2601.07619
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6f0c2657b99d4d00911ac535ff9a84982d22b4f78ea07162d36ddcbdd92a30af
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2026-01-13T00:00:00-05:00
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Learning About Learning: A Physics Path from Spin Glasses to Artificial Intelligence
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arXiv:2601.07635v1 Announce Type: cross Abstract: The Hopfield model, originally inspired by spin-glass physics, occupies a central place at the intersection of statistical mechanics, neural networks, and modern artificial intelligence. Despite its conceptual simplicity and broad applicability -- from associative memory to near-optimal solutions of combinatorial optimization problems -- it is rarely integrated into standard undergraduate physics curricula. In this paper, we present the Hopfield model as a pedagogically rich framework that naturally unifies core topics from undergraduate statistical physics, dynamical systems, linear algebra, and computational methods. We provide a concise and illustrated theoretical introduction grounded in familiar physics concepts, analyze the model's energy function, dynamics, and pattern stability, and discuss practical aspects of simulation, including a freely available simulation code. To support instruction, we conclude with classroom-ready example problems designed to mirror research practice. By explicitly connecting fundamental physics to contemporary AI applications, this work aims to help prepare physics students to understand, apply, and critically engage with the computational tools increasingly central to research, industry, and society.
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https://arxiv.org/abs/2601.07635
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fc13aecf9716713fadd00af6eef3f7789894d4b5313305427e4bc4dbccf862fe
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2026-01-13T00:00:00-05:00
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A Unified Charge-Dependent Modulation Model for AMS-02 Proton and Antiproton Fluxes during Solar Minimum
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arXiv:2601.07649v1 Announce Type: cross Abstract: We develop a unified charge-dependent solar modulation model by solving the three-dimensional Parker transport equation, incorporating a realistic wavy heliospheric current sheet to treat drift effects self-consistently. Using a local interstellar spectrum from GALPROP constrained by Voyager data, we fit the model to time-resolved proton and antiproton fluxes measured by the Alpha Magnetic Spectrometer - 02 (AMS-02) during the solar-quiet period (May 2011 to June 2022). To enable rapid parameter scans, we employ neural-network-based surrogate models to compute propagation and modulation matrices efficiently. The results demonstrate that the model simultaneously describes the observed proton and antiproton fluxes with physically reasonable parameters, providing a unified account of charge-dependent modulation.
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https://arxiv.org/abs/2601.07649
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71d31666038dedb4c98bc637f76106aadd9fd8e45492f4aab574a7b853f8ef9e
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2026-01-13T00:00:00-05:00
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A density functional theory study of amino acids on Mg and Mg-based alloys
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arXiv:2601.07680v1 Announce Type: cross Abstract: Magnesium (Mg) has mechanical properties similar to bone tissue, and Mg ions take part in the metabolism. This makes Mg of interest for biocompatible degradable body implants, provided that its high corrosion rate can be inhibited. Slightly alloying Mg and adding surface coatings can slow down the corrosion processes without significantly changing the mechanical properties. Use of coating molecules that are native to the body increase the likelihood of making the surface biocompatible, for example by use of amino acids. We here present a density functional theory (DFT) study of the adsorption on Mg(0001) of the amino acids glycine, L-proline, and L-hydroxyproline (Hyp), the main amino acid content of collagen. We investigate how binding of the functional groups of Hyp are affected when Mg(0001) is slightly alloyed with zinc, lithium or aluminium, and we also model the immersion of the systems in a water environment to see how this affects the binding.
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https://arxiv.org/abs/2601.07680
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ac0abd7b95d58c2a516ac0acdaed3e68b00541c4c836e7f4b968f5a7dd211d4a
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2026-01-13T00:00:00-05:00
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Hong-Ou-Mandel two-photon x-ray states
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arXiv:2601.07694v1 Announce Type: cross Abstract: We have observed Hong-Ou-Mandel interference of high-brightness synchrotron x-rays with a Mach-Zehnder interferometer, yielding two-photon states of potential interest for x-ray quantum optics.
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https://arxiv.org/abs/2601.07694
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cd38a2b03f6b670ea85d0ce1e8c6ccf9c3df466fab2daae5639296560e661f2d
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2026-01-13T00:00:00-05:00
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Noise2Void for Denoising Atomic Resolution Scanning Transmission Electron Microscopy Images
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arXiv:2601.07699v1 Announce Type: cross Abstract: The Noise2Void technique is demonstrated for successful denoising of atomic-resolution scanning transmission electron microscopy (STEM) images. The technique is applied to denoising atomic resolution images and videos of gold adatoms on a graphene surface within a graphene liquid cell, with the denoised experimental data qualitatively demonstrating improved visibility of both the Au adatoms and the graphene lattice. The denoising performance is quantified by comparison to similar simulated data and the approach is found to significantly outperform both total variation and simple Gaussian blurring. Compared to other denoising methods, the Noise2Void technique has the combined advantages that it requires no manual intervention during training or denoising, no prior knowledge of the sample and is compatible with real time data acquisition rates of at least 45 frames per second.
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https://arxiv.org/abs/2601.07699
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f985fb9e0a9dd2ee80c997085502f3c4a348c19e458db4a46818ddb9e15cacbe
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2026-01-13T00:00:00-05:00
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Geometric theory of constrained Schr\"odinger dynamics with application to time-dependent density-functional theory on a finite lattice
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arXiv:2601.07719v1 Announce Type: cross Abstract: Time-dependent density-functional theory (TDDFT) is a central tool for studying the dynamical electronic structure of molecules and solids, yet aspects of its mathematical foundations remain insufficiently understood. In this work, we revisit the foundations of TDDFT within a finite-dimensional setting by developing a general geometric framework for Schr\"odinger dynamics subject to prescribed expectation values of selected observables. We show that multiple natural definitions of such constrained dynamics arise from the underlying geometry of the state manifold. The conventional TDDFT formulation emerges from demanding stationarity of the action functional, while an alternative, purely geometric construction leads to a distinct form of constrained Schr\"odinger evolution that has not been previously explored. This alternative dynamics may provide a more mathematically robust route to TDDFT and may suggest new strategies for constructing nonadiabatic approximations. Applying the theory to interacting fermions on finite lattices, we derive novel Kohn--Sham schemes in which the density constraint is enforced via an imaginary potential or, equivalently, a nonlocal Hermitian operator. Numerical illustrations for the Hubbard dimer demonstrate the behavior of these new approaches.
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https://arxiv.org/abs/2601.07719
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b5c0826487323dec25cb450453d638fe762e3c5c4ee2e5b299208e5d70575e25
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2026-01-13T00:00:00-05:00
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Geometric Time-Dependent Density Functional Theory
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arXiv:2601.07724v1 Announce Type: cross Abstract: We provide a new formulation of Time-Dependent Density Functional Theory (TDDFT) based on the geometric structure of the set of states constrained to have a fixed density. Orbital-free TDDFT is formulated using a hydrodynamics equation involving a new universal density-to-current functional map. In the corresponding Kohn--Sham equation, the density is reproduced using a non-local operator. Numerical simulations for one-dimensional soft-Coulomb systems are provided.
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https://arxiv.org/abs/2601.07724
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67fd7189b0f501cd1e259dd9f17723f13264a643250bc7ff31efd16c8e7047c0
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2026-01-13T00:00:00-05:00
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Contribution of Water to Pressure and Cold Denaturation of Proteins
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arXiv:1505.07594v3 Announce Type: replace Abstract: The mechanisms of cold- and pressure-denaturation of proteins are matter of debate and are commonly understood as due to water-mediated interactions. Here we study several cases of proteins, with or without a unique native state, with or without hydrophilic residues, by means of a coarse-grain protein model in explicit solvent. We show, using Monte Carlo simulations, that taking into account how water at the protein interface changes its hydrogen bond properties and its density fluctuations is enough to predict protein stability regions with elliptic shapes in the temperature-pressure plane, consistent with previous theories. Our results clearly identify the different mechanisms with which water participates to denaturation and open the perspective to develop advanced computational design tools for protein engineering.
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https://arxiv.org/abs/1505.07594
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f5b73d8098b490f694faa1f7cba59ecfa7c6dd2926315ec47c3696ba363d2f28
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2026-01-13T00:00:00-05:00
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Strategic Geosteering Workflow with Uncertainty Quantification and Deep Learning: A Case Study on the Goliat Field
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arXiv:2210.15548v2 Announce Type: replace Abstract: The real-time interpretation of the logging-while-drilling data allows us to estimate the positions and properties of the geological layers in an anisotropic subsurface environment. Robust real-time estimations capturing uncertainty can be very useful for efficient geosteering operations. However, the model errors in the prior conceptual geological models and forward simulation of the measurements can be significant factors in the unreliable estimations of the profiles of the geological layers. The model errors are specifically pronounced when using a deep-neural-network (DNN) approximation which we use to accelerate and parallelize the simulation of the measurements. This paper presents a practical workflow consisting of offline and online phases. The offline phase includes DNN training and building of an uncertain prior near-well geo-model. The online phase uses the flexible iterative ensemble smoother (FlexIES) to perform real-time assimilation of extra-deep electromagnetic data accounting for the model errors in the approximate DNN model. We demonstrate the proposed workflow on a case study for a historic well in the Goliat Field (Barents Sea). The median of our probabilistic estimation is on-par with proprietary inversion despite the approximate DNN model and regardless of the number of layers in the chosen prior. By estimating the model errors, FlexIES automatically quantifies the uncertainty in the layers' boundaries and resistivities, which is not standard for proprietary inversion.
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https://arxiv.org/abs/2210.15548
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f25b352ee48545a3b258bb97d4de2e690cf047d60c5daf1a8015a8099ae268f2
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2026-01-13T00:00:00-05:00
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Leak Proof PDBBind: A Reorganized Dataset of Protein-Ligand Complexes for More Generalizable Binding Affinity Prediction
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arXiv:2308.09639v3 Announce Type: replace Abstract: The majority of machine learning scoring functions used in drug discovery for predicting protein-ligand binding poses and affinities have been trained on the PDBBind dataset. However, it is unclear whether these new scoring functions are actually an improvement over traditional models since often the training and test sets are cross-contaminated with proteins and ligands with high similarity, and hence they may not perform comparably well in binding prediction of unrelated protein-ligand complexes. In this work we have carefully prepared a new split of the PDBBind data set to control for data leakage, defined as proteins and ligands with high sequence and structural similarity. The resulting leak-proof (LP)-PDBBind data is used to retrain four popular SFs: AutoDock Vina, Random Forest (RF)-Score, InteractionGraphNet (IGN), and DeepDTA, to better test their capabilities when applied to new protein-ligand complexes. In particular we have formulated a new independent data set, BDB2020+, by matching high quality binding free energies from BindingDB with co-crystalized ligand-protein complexes from the PDB that have been deposited since 2020. Based on all the benchmark results, the retrained models using LP-PDBBind consistently perform better, with IGN especially being recommended for scoring and ranking applications for new protein-ligand systems.
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https://arxiv.org/abs/2308.09639
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2bb2809e3f6667f1f10ba38edb3dd34a6317fdc7eaec42cd23bee77494cfe9d1
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2026-01-13T00:00:00-05:00
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Pregnancy as a dynamical paradox: robustness, control and birth onset
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arXiv:2408.00956v3 Announce Type: replace Abstract: The timing of human labor is among the most critical determinants of neonatal survival, yet the mechanisms that govern the transition from uterine quiescence to coordinated contractions remain elusive. Here we present a dynamical-systems framework that models the pregnant uterus as a spatially extended network of electrically excitable cells regulated by sparse adaptive feedback mimicking hormonal and mechanical influences. This approach reveals how stability during gestation and sensitivity near parturition can be simultaneously maintained through the interplay of control, network structure, and noise. Our analysis shows that spontaneous contractions such as Braxton-Hicks and Alvarez waves are not epiphenomena, but functional components that reduce control effort and preserve responsiveness. Moreover, we identify preterm labor as a boundary-crossing phenomenon arising when control fails to correctly interpret early-warning signals. These results establish a unifying mechanistic theory for labor onset, yield testable predictions, and suggest new therapeutic strategies to mitigate preterm birth risk.
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https://arxiv.org/abs/2408.00956
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285a722bd5de3e777a473e7075ba45c4ad4df576dcf73430d12a2818f1428c74
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2026-01-13T00:00:00-05:00
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CANISIUS The Austrian Neutron Spin Echo Interferometer
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arXiv:2408.06216v2 Announce Type: replace Abstract: The broad band resonant spin echo interferometer, CANISIUS, is presented. CANISIUS is built in a versatile way, such that it can be operated in both a continuous broad band beam or a pulsed Time of Flight beam. This versatility also extends to the modes available to the instrument, such as Neutron Resonant Spin Echo, Spin Echo (Modulated) Small Angle Neutron Scattering and coherent averaging to produce structured wavefunctions for scattering. The instrument may also be used as an interferometer, to probe fundamental questions in quantum mechanics. In this paper we detail both the continuous and Time of Flight options of the instruments. In addition we demonstrate the applicability of our interferometer to ultra small angle scattering in a white beam. Finally we demonstrate a new spin echo interferometry tool, which uses incomplete recombination of the two path states to generate composite wavefunctions with special structure. In particular we show that this method produces neutron wavefunctions that exist in a superposition of two quantum mechanical OAM modes, l =+1 or -1 We illustrate that just as this method can be used to generate certain structured waves, it may also be used to characterize the structure of the input wavefunction.
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https://arxiv.org/abs/2408.06216
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85442590ffab6d25c01ef1ad5240102ebdd82a2de9f814aee252288f23891933
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2026-01-13T00:00:00-05:00
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Birefringence in a Silicon Beamsplitter at 2um for Future Gravitational Wave Detectors
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arXiv:2410.23711v2 Announce Type: replace Abstract: The next generation of gravitational wave detectors will move to cryogenic operation in order to reduce thermal noise and thermal distortion. This necessitates a change in mirror substrate with silicon being a good candidate. Birefringence is an effect that will degrade the sensitivity of a detector and is of greater concern in silicon due to its crystalline nature. We measure the birefringence in a float zone silicon beamsplitter since we expect there to be a large inherent birefringence due to the spatial dispersion effect. We observe that the birefringence varied between $3.44 \pm 0.12 \times 10^{-7}$ and $1.63 \pm 0.05 \times 10^{-7}$ and estimate the birefringence along the axis to be $1.64 \pm 0.5 \times 10^{-6}$ at 2um. We demonstrate this effect and argue that it strengthens the case for 2um and silicon.
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https://arxiv.org/abs/2410.23711
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3f1eba45a583b0cfa150ecd9d1d045f40a9b212e017da3b73c58b609a12a3b7a
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2026-01-13T00:00:00-05:00
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Emergent spacetime from spatial energy potentiality: a new theoretical framework for early universe cosmology
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arXiv:2502.18524v5 Announce Type: replace Abstract: We develop a comprehensive cosmological framework based on the principle that our universe originated as a three-dimensional spatial configuration governed purely by energy functionals, with time emerging dynamically through quantum loop corrections. Building on the Unified Standard Model with Emergent Gravity-Effective Field Theory (USMEG-EFT), which provides the first successful unification of quantum gravity with the Standard Model, we demonstrate that spacetime emergence occurs via a first-order phase transition when quantum-generated kinetic terms exceed a critical threshold. This transition naturally resolves the cosmological singularity problem: all curvature invariants remain finite, with $R/M_P^4 \sim 10^{-44}$ and $K/M_P^8 \sim 10^{-88}$ at the critical point. The framework makes definitive, parameter-free predictions for gravitational wave polarizations, exactly two tensor modes confirmed by LIGO-Virgo-KAGRA observations at $>99\%$ confidence, excluding competing approaches that predict additional scalar, vector, or modified polarization content. Post-emergence dynamics naturally implements Starobinsky inflation with spectral index $n_s = 0.964$ and tensor-to-scalar ratio $r = 0.004$, in excellent agreement with Planck constraints. The phase transition dynamics generate enhanced primordial non-Gaussianity $f_{\rm NL}^{\rm local} \in [0.8, 2.5]$, testable with CMB-S4 (projected $\sigma \sim 1$), and a stochastic gravitational wave background peaking in the LISA sensitivity band ($f \sim 10^{-4}$ Hz, $\Omega_{\rm GW}h^2 \sim 10^{-6}$). The framework naturally addresses the Hubble tension through scale-dependent modifications to cosmic expansion arising from residual phase transition effects.
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https://arxiv.org/abs/2502.18524
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5deb78a6c4bf229ce93e7a01c4d7565781cfefeca78d5283f9e360d8f877fbf1
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2026-01-13T00:00:00-05:00
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Cosmic acceleration as a saddle-node bifurcation: background identities and structure
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arXiv:2502.20430v2 Announce Type: replace Abstract: We show that the late-time acceleration of the universe can be understood as a codimension-one bifurcation of the Friedmann dynamical system in the variables $(H,\Omega)$. At a critical value of the density-parameter combination, a saddle-node bifurcation occurs; beyond the saddle-node, trajectories are globally attracted to a new accelerating fixed point. We obtain a normal form and a versal unfolding for the reduced dynamics, proving robustness (structural stability) of the phenomenon and deriving the characteristic square-root splitting of the emerging equilibria. We interpret the unfolding parameter as a measure of departure from adiabaticity via a modified continuity/entropy balance, thus linking acceleration to controlled non-equilibrium evolution rather than to a cosmological constant. In particular, late-time acceleration arises without invoking a separate dark-energy fluid; it emerges from a bounded unfolding of the background flow around a saddle-node organizing center. We situate this within a broader "general-relativity landscape," where control parameters act as moduli and branches of exact solutions appear as equilibrium loci, allowing bifurcation-theoretic tools to organize cosmological dynamics without introducing extra fields, and suggesting a coherent, bifurcation-guided cosmic history.
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https://arxiv.org/abs/2502.20430
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30ea9d659fa0efec4c9aac87218c4d8305a19390bd0e8691e0e175b68bcb7dcd
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2026-01-13T00:00:00-05:00
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Quantum Simulations of Chemical Reactions: Achieving Accuracy with NISQ Devices
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arXiv:2503.12084v3 Announce Type: replace Abstract: Quantum computing is viewed as a promising technology because of its potential for polynomial growth in complexity, in contrast to the exponential growth observed in its classical counterparts. In the current Noisy Intermediate-Scale Quantum (NISQ) era, the Variational Quantum Eigensolver (VQE), a hybrid variational algorithm, is utilized to simulate molecules using qubits and calculate molecular properties. However, simulating a chemical reaction to compute the reaction energy using VQE algorithm has not yet reached chemical accuracy relative to the benchmark computational chemistry methods due to limitations such as the number of qubits, circuit depth, and noise introduced within the model. To address this issue, we propose the definition of different active spaces for studying chemical reactions, incorporating irreducible representations of both the ground and excited states of the molecules. Our results demonstrate that this approach achieves chemical accuracy in predicting the reaction energy for various reactions. For all reactions studied, the difference in reaction energies between conventional computational chemistry methods and the quantum-classical hybrid VQE algorithm is less than 1 kcal/mol. Furthermore, our analysis simplifies the process of selecting active spaces and electrons for each reaction, reducing it to a single optimal combination that ensures the chemical accuracy for each reaction.
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https://arxiv.org/abs/2503.12084
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5d86d0bdc0b89bcd60da3ccf360bf6979c787fac1baf7e60cf0a25c07e2d5bf3
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2026-01-13T00:00:00-05:00
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A Review of Urban Resilience Frameworks: Transferring Knowledge to Enhance Pandemic Resilience
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arXiv:2503.17371v2 Announce Type: replace Abstract: Urbanization is rapidly increasing, with urban populations expected to grow significantly by 2050, particularly in developing regions. This expansion brings challenges related to chronic stresses and acute shocks, such as the COVID-19 pandemic, which has underscored the critical role of urban form in a city's capacity to manage public health crises. Despite the heightened interest in urban resilience, research examining the relationship between urban morphology and pandemic resilience remains limited, often focusing solely on density and its effect on disease transmission. This work aims to address this gap by evaluating existing frameworks that analyze the relationship between urban resilience and urban form. By critically reviewing these frameworks, with a particular emphasis on theoretical and quantitative approaches, this study seeks to transfer the knowledge gained to better understand the relationship between pandemic resilience and urban morphology. The work also links theoretical ideas with quantitative frameworks, offering a cohesive analysis. The anticipated novelty of this study lies in its comprehensive assessment of urban resilience frameworks and the identification of the current gaps in integrating resilience to pandemic thinking into urban planning and design. The goal is not only to enhance the understanding of urban resilience but also to offer practical guidance for developing more adaptive and effective frameworks for assessing resilience to pandemics in urban environments, thereby preparing cities to better withstand and recover from future crises.
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https://arxiv.org/abs/2503.17371
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59b17f0e5f2afabdd0ce4e930fc5e0db00bee54b0ecb869bcda95ebbf9c7e257
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2026-01-13T00:00:00-05:00
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Refractive Index, Its Chromatic Dispersion, and Thermal Coefficients of Four Less Common Glycols
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arXiv:2504.11819v2 Announce Type: replace Abstract: We report comprehensive measurements of the refractive index as a function of wavelength and temperature for four less commonly studied glycols: pentaethylene glycol, hexaethylene glycol, dipropylene glycol (mixture of isomers), and tripropylene glycol. The measurements cover the spectral range of 0.39-1.07 ${\mu}$m and temperatures from 1${\deg}$C to 45${\deg}$C. The data were modeled using a two-pole Sellmeier equation, with temperature dependence expressed through wavelength-dependent thermal coefficients. Four fitting models (Sellmeier and Cauchy) with different numbers of parameters were tested. For pentaethylene glycol, results from all models are shown; for the remaining glycols, only the two-pole Sellmeier fits are presented in tabular form. Thermal coefficient values for six wavelengths of practical importance are also tabulated. Experimental uncertainties in refractive index, wavelength, and temperature were rigorously evaluated and incorporated into the analysis. The influence of sample purity, including residual water content and manufacturer-reported impurities, was assessed and accounted for in the uncertainty estimates. To our knowledge, this is the first dataset to systematically characterize both chromatic dispersion and thermal variation of the refractive index for these glycols over such a broad spectral and temperature range. The validated fitting equations and parameters are suitable for use in optical modeling, materials characterisation, and related applications. All raw data are available in a publicly accessible repository.
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https://arxiv.org/abs/2504.11819
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17e9caa3bf03073f4bdec77fd9baa709fd77e0d7e6f182bbeb0b8630bc7cb2fb
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2026-01-13T00:00:00-05:00
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The Dirac equation: historical context, comparisons with the Schr\"odinger and Klein-Gordon equations, and elementary consequences
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arXiv:2504.17797v2 Announce Type: replace Abstract: This paper offers educational insight into the Dirac equation, examining its historical context and contrasting it with the earlier Schr\"odinger and Klein-Gordon (KG) equations. The comparison highlights their Lorentz transformation symmetry and potential probabilistic interpretations. We explicitly solve the free-particle dynamics in Dirac's model, revealing the emergence of negative-energy solutions. This discussion examines the Dirac Sea Hypothesis and explores the solutions' inherent helicity. Additionally, we demonstrate how the Dirac equation accounts for spin and derive the Pauli equation in the non-relativistic limit. The Foldy-Wouthuysen transformation reveals how the equation incorporates spin-orbit interaction and other relativistic effects, ultimately leading to the fine structure of hydrogen. A section on relativistic covariant notation is included to emphasize the invariance of the Dirac equation, along with more refined formulations of both the KG and Dirac equations. Designed for undergraduate students interested in the Dirac equation, this resource provides a historical perspective without being purely theoretical. Our approach underscores the significance of a pedagogical method that combines historical and comparative elements to profoundly understand the role of the Dirac equation in modern physics.
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https://arxiv.org/abs/2504.17797
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7394cb0addd936ca305242343d9372441a9d8c9c0e46036727e9b1e89323b4bc
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2026-01-13T00:00:00-05:00
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Universal low-depth two-unitary design of programmable photonic circuits
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arXiv:2504.19358v2 Announce Type: replace Abstract: The development of large-scale, programmable photonic circuits capable of performing generic matrix-vector multiplication is essential for both classical and quantum information processing. However, this goal is hindered by high losses, hardware errors, and difficulties in programmability. We propose an enhanced architecture for programmable photonic circuits that minimizes circuit depth and offers analytical programmability, properties that have not been simultaneously achieved in previous circuit designs. Our proposal exploits a previously overlooked representation of general nonunitary matrices as sums of two unitaries. Furthermore, similar to the traditional singular value decomposition-based circuits, the circuits in our unitary-sum-based architecture inherit the advantages of the constituent unitary circuits. Overall, our proposal provides a significantly improved solution for matrix-vector multiplication compared to the established approaches.
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https://arxiv.org/abs/2504.19358
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bbbeb90f06524bb45a3e8f0d71fe2b2b0d9904982f13683381c919c25ca95c57
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2026-01-13T00:00:00-05:00
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Steering reaction flux by coupling product channels
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arXiv:2504.21727v2 Announce Type: replace Abstract: We demonstrate a method for controlling the outcome of an ultracold chemical few-body reaction by redirecting a tunable fraction of reaction flux from one selected product channel to another one. In the reaction, three ultracold atoms collide to form a diatomic molecule. This product molecule can be produced in various internal states, characterizing the different product channels of the reaction. Our scheme relies on the coupling between two such product channels at an avoided molecular energy level crossing in the presence of an external magnetic field. The degree of coupling can be set by the magnetic field strength and allows for a widely tunable flux control between the two channels. This scheme is quite general and also holds great promise for a large variety of chemical processes with diverse species, since molecular energy level crossings are ubiquitous in molecular systems and are often easily accessible by standard laboratory equipment.
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https://arxiv.org/abs/2504.21727
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a6ad8c28daaa277a9514447ac1eb6f940839706d51992b45cc97444e91e7f65f
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2026-01-13T00:00:00-05:00
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Time-dependent Hole States in Multiconfigurational Time-Dependent Hartree-Fock Approaches: A Time-Domain Generalization of Extended Koopmans' Theorem
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arXiv:2505.11290v2 Announce Type: replace Abstract: We introduce a framework for resolving electron-hole dynamics within wavefunction-based multiconfigurational time-dependent Hartree-Fock (MCTDHF) theory. Central to this framework is a time-domain generalization of the extended Koopmans' theorem, which rigorously defines time-dependent hole states through single-electron removal. From this foundation, we prove the existence of exact equations of motion for time-dependent Dyson orbitals, enabling instantaneous construction of photofragments' reduced density matrices. The formalism further yields a systematic procedure to extract hole-resolved observables, such as channel-resolved photoelectron momentum distributions, directly from time-dependent \textit{ab initio} wavefunctions. As a demonstration, we employ an attosecond $\omega-2\omega$ laser strategy to control hole dynamics, thereby resolving a long-standing challenge in MCTDHF simulations. This advance opens a pathway for exploring correlated multielectron dynamics in atoms and molecules under ultrafast laser fields.
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https://arxiv.org/abs/2505.11290
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b74b71973f08c893f644a6012801000f1bdd563aadfd7d0049a818e05916d37e
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2026-01-13T00:00:00-05:00
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EMetaNode: Electromechanical Metamaterial Node for Broadband Vibration Attenuation and Self-powered Sensing
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arXiv:2506.02960v2 Announce Type: replace Abstract: Recent advances in mechanical metamaterials and piezoelectric energy harvesting provide exciting opportunities to guide and convert the mechanical energy in electromechanical systems for autonomous sensing and vibration control. However, practical realizations remain rare due to the lack of advanced modeling methods and interdisciplinary barriers. By integrating mechanical metamaterials with power electronics-based interface circuits, this paper makes a breakthrough with an electromechanical friction-induced metamaterial node, which realizes self-powered sensing and broadband vibration attenuation in the same time. A reduced-order modeling-based numerical harmonic balance method has been established for general nonlinear metamaterials with local nonlinearities, significantly enhancing computational efficiency. The electromechanical friction induced by synchronized switching interface circuits has been revealed for the first time, leading to energy harvesting abilities and the broader nonlinear bandgap and higher harmonics induced vibration attenuation. Experimentally, an electromechanical metamaterial node is realized for self-powered sensing of temperature and acceleration data, highlighting its potential for structural health monitoring and Internet of Things applications. This study provides a practical path to digitalizing structures and systems for autonomous sensing and vibration control by combining advanced interface circuits with mechanical metamaterials.
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https://arxiv.org/abs/2506.02960
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d71ee247a43a3d90982f143084f0b6172f7e481f3f3b69361b0f357f9f1ae80c
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2026-01-13T00:00:00-05:00
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Distinct Berry Phases in a Single Triangular M\"{o}bius Microwave Resonator
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arXiv:2506.07320v3 Announce Type: replace Abstract: We report the experimental observation of two distinct Berry phases ($+\frac{2\pi}{3}$ and $-\frac{2\pi}{3}$) generated on the surface of a M\"{o}bius cavity resonator at microwave frequencies supporting the TE$_{1,0,n}$ mode family. This resonator consists of a twisted, mirror-asymmetric prism with a cross-section of the triangular $D_3$ symmetry group, bent around on itself to form a ring. This geometric class supports resonant modes with nonzero electromagnetic helicity (i.e. nonzero $\vec{E}\cdot\vec{B}$ product) at microwave frequencies. There exist modes with three-fold rotational symmetry as well as those that exhibit no rotational symmetry. The latter result in an accumulated Berry phase whilst the former do not, which is determined from the measured frequency shift of the modes when compared to a mirror-symmetric resonator of otherwise equivalent geometry.
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https://arxiv.org/abs/2506.07320
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879763b3def72abd4f724f21bf9874142bb26fdea3088730071606096a63ba19
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2026-01-13T00:00:00-05:00
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Resolvent4py: a parallel Python package for analysis, model reduction and control of large-scale linear systems
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arXiv:2506.20539v2 Announce Type: replace Abstract: In this paper, we present resolvent4py, a parallel Python package for the analysis, model reduction and control of large-scale linear systems with millions or billions of degrees of freedom. This package provides the user with a friendly Python-like experience (akin to that of well-established libraries such as numpy and scipy), while enabling MPI-based parallelism through mpi4py, petsc4py and slepc4py. In turn, this allows for the development of streamlined and efficient Python code that can be used to solve several problems in fluid mechanics, solid mechanics, graph theory, molecular dynamics and several other fields.
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https://arxiv.org/abs/2506.20539
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195af982c2797e515840bb09fe0d891b524647e68527f03cb599e0e4d2a1584e
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2026-01-13T00:00:00-05:00
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Online Electron Reconstruction at CLAS12
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arXiv:2507.05274v2 Announce Type: replace Abstract: Online reconstruction is key for monitoring purposes and real time analysis in High Energy and Nuclear Physics experiments. A necessary component of reconstruction algorithms is particle identification that combines information left by a particle passing through several detector components to identify the particle's type. Of particular interest to electroproduction Nuclear Physics experiments such as CLAS12 is electron identification which is used to trigger data recording. A machine learning approach was developed for CLAS12 to reconstruct and identify electrons by combining raw signals at the data acquisition level from several detector components. This approach achieves an electron identification purity above 75% whilst retaining an efficiency close to 100%. The machine learning tools are capable of running at high rates exceeding the data acquisition rates and will allow electron reconstruction in real time. This work enhances online analyses and monitoring and can contribute to improved triggering at CLAS12. This machine learning driven approach will also be crucial for experiments aiming to transition to streaming readout operations where online reconstruction will be a key component of the data taking paradigm.
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https://arxiv.org/abs/2507.05274
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0f91160e6e653eb4519859bb52b9037f43e533ab286d5abd3853e2027b82f856
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2026-01-13T00:00:00-05:00
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Direct-3D Variational Bayesian Surface Wave Inversion and Its Application to Ambient Noise Tomography beneath Great Britain
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arXiv:2507.15390v2 Announce Type: replace Abstract: We present a new, variational, fully nonlinear, probabilistic ambient noise tomography method, which estimates subsurface structure and quantifies the corresponding uncertainties directly in three dimensions (3D) from inter-receiver seismic surface wave dispersion data. We use the method to invert for high resolution 3D seismic velocity models of the upper crust beneath Great Britain using seismic ambient noise data recorded around the region - a task that proved too high-dimensional and hence computationally demanding for Monte Carlo sampling to converge to a stable solution. We compare the inversion results from the new method to those obtained from two standard, indirect inversion methods, in which 2D (geographical) surface wave velocity maps and 1D (depth) shear velocity profiles are estimated in two separate, consecutive steps. The results show that the direct-3D scheme preserves better lateral continuity and produces better data fit than the two-step methods, and provides information about lateral correlations that is absent from the two-step solutions. The inversion results are consistent with large-scale geology of Great Britain, and for the first time provide seismologically-imaged evidence of the Great Glen Fault and other major tectonic faults. We therefore propose that direct-3D inversion schemes should be used where possible for surface wave inversion as they provide improved results at little additional computational cost.
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https://arxiv.org/abs/2507.15390
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ae504ad35b53f70bf401e4d637b57e735d0d7baffc0605c5455b344238c213ef
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2026-01-13T00:00:00-05:00
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Physics-informed, boundary-constrained Gaussian process regression for the reconstruction of fluid flow fields
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arXiv:2507.17582v3 Announce Type: replace Abstract: Gaussian process regression techniques have been used in fluid mechanics for the reconstruction of flow fields from a reduction-of-dimension perspective. A main ingredient in this setting is the construction of adapted covariance functions, or kernels, to obtain such estimates. In this paper, we present a general method for constraining a prescribed Gaussian process on an arbitrary compact set. The kernel of the pre-defined process must be at least continuous and may include other information about the studied phenomenon. This general boundary-constraining framework can be implemented with high flexibility for a broad range of engineering applications. From this, we derive physics-informed kernels for simulating two-dimensional velocity fields of an incompressible (divergence-free) flow around aerodynamic profiles. These kernels allow to define Gaussian process priors satisfying the incompressibility condition and the prescribed boundary conditions along the profile in a continuous manner. We describe an adapted numerical method for the boundary-constraining procedure parameterized by a measure on the compact set. The relevance of the methodology and performances are illustrated by numerical simulations of flows around a cylinder and a NACA 0412 airfoil profile, for which no observation at the boundary is needed at all.
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https://arxiv.org/abs/2507.17582
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729efdf3d6cc8a56cae7e9b69951b3161755795702b1e6a45003ce3c5cd3ceea
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2026-01-13T00:00:00-05:00
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Suppressing secondary shock waves in jam-absorption driving via string-stable support vehicles
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arXiv:2508.03604v2 Announce Type: replace Abstract: As a freeway-driving strategy, jam-absorption driving (JAD) clears a traffic shock wave (stop-and-go wave) by slowing down a single vehicle, called the absorbing vehicle. However, JAD may destabilize the traffic flow upstream of this vehicle, generating secondary shock waves. This study proposes a method to suppress secondary shock waves by controlling the behavior of connected and automated vehicles (CAVs) upstream of the absorbing vehicle, called support vehicles (SVs). A string-stability-based control method is applied in which SVs dynamically extend their time gaps to provide support driving (SD) for JAD. Numerical simulations revealed that SD damped perturbations caused by the absorbing vehicle and prevented secondary shock waves, consistent with the head-to-tail string stability criterion. Combining JAD and SD reduced fuel consumption and collision risk compared with the JAD-only method, but increased travel time. Reverting the extended time gap to its initial value reduced travel time while maintaining low collision risk compared with the non-reverting method, albeit with increased fuel consumption. Thus, combining JAD and SD effectively eliminates the target shock wave while suppressing secondary shock waves with guaranteed string stability.
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https://arxiv.org/abs/2508.03604
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3868b0b331db3203873483919e8abfcedee5f49fca5db07374aceb0fa2edd371
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2026-01-13T00:00:00-05:00
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Generation of High Order Harmonics in Vacuum for Various Configurations of Interacting Electromagnetic Field
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arXiv:2508.09214v2 Announce Type: replace Abstract: High order harmonic (HOH) generation by interacting extremely intense electromagnetic waves in the quantum vacuum is investigated within the framework of the Heisenberg-Euler formalism. We consider here the process in the lowest order of a perturbation theory relative to the electromagnetic (EM) beam intensity, giving contribution to the HOH generation. The main expressions are obtained for a general geometry, whyle polarizations of different sub-beams forming the EM beam focus are almost the same. Nevertheless, explicit expressions for the HOH generation are derived for the $4\pi$-dipole in-coming waves and for the two crossing Gaussian beams. The former geometry of the EM beam is optimal at a given EM wave power, whereas the latter one is more realistic from the experimental point of view. We consider also a relationship of our present general results with the results, obtained earlier for the HOH generation during of collision of two plane electromagnetic waves.
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https://arxiv.org/abs/2508.09214
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50a495975b5fb5c22b13757e9a929032dd9b49a9bef1692b1a9374d8b8d8dc7a
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2026-01-13T00:00:00-05:00
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Similarities in the Initiation of Upward Positive and Downward Negative Lightning Flashes
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arXiv:2508.09440v2 Announce Type: replace Abstract: This study examines the relationship between upward negative stepped leader pulses in upward positive lightning and preliminary breakdown pulses (PBPs) in downward negative lightning discharges. Through analysis of simultaneous channel-base current and electric field data from the S\"{a}ntis tower in Switzerland, we found notable similarities between the "Category A" and "B" pulses associated with the initial continuous current of upward negative leaders, and the "Classical" and "Narrow" PBPs observed in downward negative flashes. Statistical comparisons reveal correlations between electric field and current parameters for Category A pulses, supporting the field-current relationship for preliminary breakdown proposed in previous studies. These results suggest that similar physical processes may be involved in the early stages of negative leader development in both upward and downward lightning, providing valuable insights into lightning initiation that could not be obtained from conventional field measurements alone. Furthermore, high-speed camera footage revealed that Category B pulses can be produced by a downward-propagating recoil leader. As a whole, these findings demonstrate that detailed observations of upward lightning can offer valuable insight into the complex processes underlying lightning initiation and propagation.
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https://arxiv.org/abs/2508.09440
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77ecae2ba42dfc769bc9c0024e1b6a08b837e2be4bedc98ed9beba9711afd314
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2026-01-13T00:00:00-05:00
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Irreversibility and symmetry breaking in the creation and annihilation of defects in active living matter
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arXiv:2508.15622v2 Announce Type: replace Abstract: Active living matter continuously creates and annihilates topological defects in a process that remains poorly understood. Here, we investigate these dynamics in two distinct active living systems: swarming bacteria and human bronchial epithelial cells. Despite their entirely different evolutionary origins, biological functions, and physical scales, both systems exhibit half-integer defects, consistent with the nematic phase. However, in contrast to active nematic theory, we find that defect creation and annihilation undergoes spatial symmetry breaking. We propose that these results stem from a fundamental dualism between nematic structural organization and generated polar forces, which are intrinsic to living systems. Furthermore, estimation of entropy production reveals that creation and annihilation are not reversed processes. Our findings challenge conventional nematic models and emphasize the role of defect-mediated dynamics in non-equilibrium biological systems as a major source of entropy production.
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https://arxiv.org/abs/2508.15622
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7c2fefb5668608cc2f2c9d376c22bc3fc900c195fe564feed51c18bec8a70198
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2026-01-13T00:00:00-05:00
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Spatiotemporal shaping of attosecond X-rays with time-dependent orbital angular momentum
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arXiv:2508.19020v2 Announce Type: replace Abstract: Attosecond X-ray pulses are indispensable for exploring ultrafast phenomena in matter on Angstrom and attosecond scales. Here we propose a new method to realize spatiotemporal shaping of attosecond X-rays through temporal control of the orbital angular momentum mode content using an X-ray free-electron laser. The method exploits transverse-mode-dependent frequency pulling in a deliberately detuned second stage, together with slippage between the seed and the amplified radiation. Three-dimensional simulations show a double-spike waveform in which the two spikes carry different dominant topological charges. The spike separation is tunable and can reach several hundred attoseconds. This provides a source-level route to spatiotemporally structured attosecond X-rays with controllable temporal structure and topological mode content.
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https://arxiv.org/abs/2508.19020
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2aec3b110ad3e7abba739790d788d99288f2428ed72681c7dd7df15e1eccd829
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2026-01-13T00:00:00-05:00
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The Photochemical Birth of the Hydrated Electron in Liquid Water
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arXiv:2508.19702v3 Announce Type: replace Abstract: The photophysics and photochemistry associated with irradiating UV light in liquid water is central to numerous physical, chemical and biological processes. One of the key events involved in this process is the generation of the hydrated electron. Despite long study from both experimental and theoretical fronts, a unified understanding of the underlying mechanisms associated with the generation of the solvated electron have remained elusive. Here, using excited-state molecular dynamics simulations of condensed phase photoexcited liquid water, we unravel the key sequence of chemical events leading to the creation of the hydrated electron on the excited state. The process begins through the excitation localized mostly on specific topological defects in the hydrogen-bond network of water which is subsequently followed by two main reaction pathways. The first, leads to the creation of a hydrogen atom culminating in non-radiative decay back to the ground-state within 100 femtoseconds. The second involves a proton coupled electron transfer, giving rise to the formation of the hydronium ion, hydroxyl radical and the hydrated excess electron on the excited-state. This process is facilitated by ultrafast coupled rotational and translational motions of water molecules leading to the formation of water mediated ion-radical pairs in the network. These species can survive on the picosecond timescale and ultimately modulate the emission of visible photons. All in all, our findings provide fresh perspectives into the interpretation of several independent time-dependent spectroscopies measured over the last decades, paving the way for new directions on both theoretical and experimental fronts.
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https://arxiv.org/abs/2508.19702
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e78c54bfc1b5200b1bda2366754e45e051a939d227d9fa1de5fd7b3be9011ea1
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2026-01-13T00:00:00-05:00
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Earthquake Source Depth Determination using Single Station Waveforms and Deep Learning
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arXiv:2509.02346v2 Announce Type: replace Abstract: In areas with limited station coverage, earthquake depth constraints are much less accurate than their latitude and longitude. Traditional travel-time-based location methods struggle to constrain depths due to imperfect station distribution and the strong trade-off between source depth and origin time. Identifying depth phases at regional distances is usually hindered by strong wave scattering, which is particularly challenging for low-magnitude events. Deep learning algorithms, capable of extracting various features from seismic waveforms, including phase arrivals, phase amplitudes, as well as phase frequency, offer promising constraints to earthquake depths. In this work, we propose a novel depth feature extraction network (named VGGDepth), which directly maps seismic waveforms to earthquake depth using three-component waveforms. The network structure is adapted from VGG16 in computer vision. It is designed to take single-station three-component waveforms as inputs and produce depths as outputs, achieving a direct mapping from waveforms to depths. Two scenarios are considered in our model development: (1) training and testing solely on the same seismic station, and (2) generalizing by training and testing on different seismic stations within a particular region. We demonstrate the efficacy of our methodology using seismic data from the 2016-2017 Central Apennines, Italy earthquake sequence. Results demonstrate that earthquake depths can be estimated from single stations with uncertainties of hundreds of meters. These uncertainties are further reduced by averaging results from multiple stations. Our method shows strong potential for earthquake depth determination, particularly for events recorded by single or sparsely distributed stations, such as historically instrumented earthquakes.
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https://arxiv.org/abs/2509.02346
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513f3feeeea2887ea006f711ee81a53628d38701460ad6bb3527d43d4b9181d2
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2026-01-13T00:00:00-05:00
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Low-rank matrix and tensor approximations for compression of machine-learning interatomic potentials
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arXiv:2509.04440v2 Announce Type: replace Abstract: Machine-learning interatomic potentials (MLIPs) have become a mainstay in computationally-guided materials science, surpassing traditional force fields due to their flexible functional form and superior accuracy in reproducing physical properties of materials. This flexibility is achieved through mathematically-rigorous basis sets that describe interatomic interactions within a local atomic environment. The number of parameters in these basis sets influences both the size of the training dataset required and the computational speed of the MLIP. Consequently, compressing MLIPs by reducing the number of parameters is a promising route to more efficient simulations. In this work, we use low-rank matrix and tensor factorizations under fixed-rank constraints to achieve this compression. In addition, we demonstrate that an algorithm with automatic rank augmentation helps to find a deeper local minimum of the fitted potential. The methodology is mainly verified using the Moment Tensor Potential (MTP) model and benchmarked on multi-component systems: a Mo-Nb-Ta-W medium-entropy alloy, molten LiF-NaF-KF, and a glycine molecular crystal. The proposed approach achieves up to 50 % compression without any loss of MTP accuracy. We also demonstrate that the developed methodology is universal and can be applied to compress other MLIPs on the example of Atomic Cluster Expansion (ACE).
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https://arxiv.org/abs/2509.04440
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9195f7a74e128d667729f1318c61dfc9a43f397ccc3526af3e22657618f2a092
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2026-01-13T00:00:00-05:00
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Capillary hysteresis induced by gap-resolved meniscus dynamics on Faraday instability in Hele-Shaw cells
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arXiv:2509.09475v2 Announce Type: replace Abstract: Existing theoretical analyses on Faraday instability in Hele-Shaw cells typically adopt gap-averaged governing equations and rely on Hamraoui's model coming from molecular kinetics theory, thereby oversimplifying essential transverse information, such as contact line velocity and capillary hysteresis, and conflicting with the unsteady meniscus dynamics. In this paper, a gap-resolved approach is developed by directly modeling the transverse gap flow and the contact angle dynamics, which overcomes the aforementioned limitations, ultimately yielding a modified damping with respect to the static contact angle and hysteresis range. A novel amplitude equation for linear Faraday instability is derived that combines this damping and the gap-averaged counterpart based on the oscillatory Stokes boundary layer, with the viscous dissipation preserved. By means of Lyapunov's first method, an explicit analytical expression for the critical stability boundary is established. Two series of laboratory experiments are performed that focus, respectively, on evolutions of the lateral meniscus and the longitudinal free surface near the Faraday onset, from which key parameters relevant to the theory are precisely measured. Based on the experimental data, the validity of the proposed mathematical model for addressing the Faraday instability problem in Hele-Shaw cells is confirmed, and the generation and development mechanisms of the onset are clarified. In the asymptotic analysis, the inclusion of contact angle dynamics increases the overall damping and thus partially compensates for the frequency detuning introduced by oscillatory Stokes flow approximation.
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https://arxiv.org/abs/2509.09475
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43c08a8c6e3e24e0d45a2adff034b0ac975597e71fb4597858ea2aa7d2611a97
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2026-01-13T00:00:00-05:00
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Unveiling Gender Dynamics in Introductory Physics Labs
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arXiv:2509.10299v2 Announce Type: replace Abstract: The persistent underrepresentation of women and gender minorities within the physical sciences remains a significant issue. This study investigates gender dynamics in introductory algebra-based physics laboratories, focusing on participation, task preferences, and comfort levels. Statistical analysis revealed no significant gender difference in overall participation rates during lab activities. However, significant gender-based disparities emerged in both task preference [\(\chi^2(\text{df}=3) = 9.548,~ p = 0.023, ~ \alpha = 0.05 \)] and comfort levels [\(\chi^2(\text{df}=3) = 7.906,~ p = 0.048, ~ \alpha = 0.05\)]. Male students significantly preferred and felt more comfortable with hands-on equipment handling and data collection, whereas female students more frequently preferred and reported higher comfort with analytical and documentation tasks like note-taking, calculations, and report writing. Qualitative responses highlighted additional challenges reported by some women, including exclusion from group discussions and reluctance to contribute ideas in male-dominated groups. These findings suggest that while overall participation may appear gender-neutral, gendered patterns in task allocation and comfort persist. The results underscore the need for instructional strategies that promote equitable engagement and foster inclusive laboratory environments in physics education.
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https://arxiv.org/abs/2509.10299
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dcdd3f4c638c448c10e3e8645f47a8574041015ee56f493f9e6f85c4ccf6e77a
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2026-01-13T00:00:00-05:00
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Volumetric ultrasound imaging with a sparse matrix array and integrated fiber-optic sensing for robust needle tracking in interventional procedures
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arXiv:2509.11310v3 Announce Type: replace Abstract: Accurate visualization of interventional devices, such as medical needles, is essential for the safe and effective guidance of minimally invasive procedures. Ultrasound (US) imaging is widely used for needle guidance, but the two-dimensional nature of most clinical probes limits accurate three-dimensional (3D) localization, particularly of the needle tip. We present a novel system that integrates volumetric US imaging with 3D needle tracking by combining a fiber-optic hydrophone embedded in the needle and a sparse spiral US array. Real-time volumetric imaging was achieved using plane-wave techniques, while precise needle tip tracking was enabled through communication between the probe and hydrophone. The feasibility of the approach was demonstrated using a nerve block training phantom. This proof-of-concept system enables simultaneous volumetric anatomical imaging and 3D needle tip tracking, with strong potential to enhance the efficacy and safety of image-guided interventional procedures.
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https://arxiv.org/abs/2509.11310
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fd8e89c08f2baf5c027d9cc2638b986ad4b0a262ecdc62d5e64f115d56dd4a52
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2026-01-13T00:00:00-05:00
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The Quantum Method of Planes - Local Pressure Definitions for Machine Learning Potentials
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arXiv:2509.16257v2 Announce Type: replace Abstract: Stress, or pressure, is a central quantity in engineering and remains vital in molecular modelling. However, the commonly used virial stress tensor is invalid for an inhomogeneous fluid, which is essential in fluid dynamics and non-equilibrium molecular dynamics (NEMD) simulation. This is solved by using the method of planes (MoP), a mechanical form of pressure, simply interpreted as the force divided by area, yet is derived from the firm foundations of statistical mechanics. We present an extension of MoP stress1 to the MACE potential, a particular form of machine learning (ML) potentials allowing the incorporation of quantum mechanical (QM) physics into classical simulation. We present the derivation of this local stress for the MACE potential using the theoretical framework set out by Irving and Kirkwood 2 . For the test case of an interface between water and Zirconium Oxide, we show that the MoP measures the correct force balance while the virial form fails. Further, we demonstrate that this planar definition of stress is valid arbitrarily far from equilibrium, showing exact conservation every timestep in a control volume bounded by MoP planes. This links the stress directly to the conservation equations and demonstrates the validity in non equilibrium molecular dynamics (NEMD) systems. All code to reproduce these validations for any MACE system, together with ASE accelerated code to calculate the MoP, is provided as open source. This work helps build the foundation to extend the ML revolution in materials to NEMD and molecular fluid dynamics modelling.
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https://arxiv.org/abs/2509.16257
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08c3f59971ae7538db4eff5fa83140b3d62eab7977dc410a85d98feb6462ed97
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2026-01-13T00:00:00-05:00
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Homophily and wealth inequality shape mitigation behavior in coupled social-climate models
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arXiv:2509.17252v2 Announce Type: replace Abstract: Understanding the role of human behavior in shaping environmental outcomes is crucial for addressing global challenges such as climate change. Environmental systems are influenced not only by natural factors like temperature, but also by human decisions regarding mitigation efforts, which are often based on forecasts or predictions about future environmental conditions. Over time, different outcomes can emerge, including scenarios where the environment deteriorates despite efforts to mitigate, or where successful mitigation leads to environmental resilience. Additionally, fluctuations in the level of human participation in mitigation can occur, reflecting shifts in collective behavior. In this study, we consider a variety of human mitigation decisions, in addition to the feedback loop that is created by changes in human behavior because of environmental changes. While these outcomes are based on simplified models, they offer important insights into the dynamics of human decision-making and the factors that influence effective action in the context of environmental sustainability. This study aims to examine key social dynamics influencing society's response to a worsening climate. While others conclude that homophily prompts greater warming unconditionally, this model finds that homophily can prevent catastrophic effects given a poor initial environmental state. Assuming that poor countries have the resources to do so, a consensus in that class group to defect from the strategy of the rich group (who are generally incentivized to continue ``business as usual'') can frequently prevent the vegetation proportion from converging to 0.
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https://arxiv.org/abs/2509.17252
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2026-01-13T00:00:00-05:00
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Nonlinear anisotropic equilibrium reconstruction in axisymmetric magnetic mirrors
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arXiv:2509.17288v3 Announce Type: replace Abstract: Magnetic equilibrium reconstruction is a crucial simulation capability for interpreting diagnostic measurements of experimental plasmas. Equilibrium reconstruction has mostly been applied to systems with isotropic pressure and relatively low plasma $\beta = 2\mu_0p/B^2$. This work extends nonlinear equilibrium reconstruction to high-$\beta$ plasmas with anisotropic pressure and applies it to the Wisconsin High Temperature Superconducting Axisymmetric Magnetic Mirror experiments to infer the presence of sloshing ions. A novel basis set for the plasma profiles and machine learning algorithm using scalable constrained Bayesian optimization allow accurate nonlinear reconstructions with uncertainty quantification to be made more quickly with fewer experimental diagnostics and improves the robustness of reconstructions at high $\beta$. In addition to WHAM and other mirrors, such reconstruction techniques are potentially attractive in high-performance devices with constrained diagnostic capabilities such as fusion power plants.
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https://arxiv.org/abs/2509.17288
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2a43e68dfa8a6f44bed9c31b29d7d766fba60f7c48bc7af76005b212cfad4783
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2026-01-13T00:00:00-05:00
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Unveiling the Shortwave Absorption Spectra of Alumina Aerosols: Implications for Solar Radiation Modification
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arXiv:2509.24246v2 Announce Type: replace Abstract: Alumina is proposed for Stratospheric Aerosol Injection (SAI)-based solar radiation modification due to its presumed ability to scatter sunlight strongly while absorbing weakly. Alumina is assigned negligible solar shortwave absorption in climate models; this assumption is not validated owing to technological challenges in quantifying its weak absorption signals. We report alumina's shortwave imaginary refractive index $k$, a determinant of its absorption strength, using sensitive in situ photoacoustic spectrometry, finding values ranging from $1.4 \times 10^{-4}$ to $1.2 \times 10^{-3}$. Particle-scale electron energy-loss spectroscopy provided independent validation and revealed that the non-ideal absorption arises from oxygen vacancy defects in the alumina's crystal structure. Aerosol chemistry climate model simulations to evaluate shortwave absorption radiative effects revealed insignificant impacts on radiative forcing and stratospheric warming. Our findings indicate that alumina's shortwave absorption, previously reported as a source of uncertainty, is unlikely to affect SAI impact calculations.
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https://arxiv.org/abs/2509.24246
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46549246250ad7f4db32093fb6caf8b1109aa6f9dbdbde573ce7ff6cc8a6a68e
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2026-01-13T00:00:00-05:00
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TBPLaS 2.0: a Tight-Binding Package for Large-scale Simulation
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arXiv:2509.26309v2 Announce Type: replace Abstract: The common exact diagonalization-based techniques to solving tight-binding models suffer from O(N^2) and O(N^3) scaling with respect to model size in memory and CPU time, hindering their applications in large tight-binding models. On the contrary, the tight-binding propagation method (TBPM) can achieve linear scaling in both memory and CPU time, and is capable of handling large tight-binding models with billions of orbitals. In this paper, we introduce version 2.0 of TBPLaS, a package for large-scale simulation based on TBPM. This new version brings significant improvements with many new features. Existing Python/Cython modeling tools have been thoroughly optimized, and a compatible C++ implementation of the modeling tools is now available, offering efficiency enhancement of several orders. The solvers have been rewritten in C++ from scratch, with the efficiency enhanced by several times or even by an order of magnitude. The workflow of utilizing solvers has also been unified into a more comprehensive and consistent manner. New features include spin texture, Berry curvature and Chern number calculation, partial diagonalization for specific eigenvalues and eigenstates, analytical Hamiltonian, and GPU computing support. The documentation and tutorials have also been updated to the new version. In this paper, we discuss the revisions with respect to version 1.3 and demonstrate the new features. Benchmarks on modeling tools and solvers are also provided.
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https://arxiv.org/abs/2509.26309
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844ae26a8da29c8cd30ac5486d2121bd0128832eac69022c88a3e91544d6cab3
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2026-01-13T00:00:00-05:00
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Accelerating Molecular Dynamics Simulations with Foundation Neural Network Models using Multiple Time-Step and Distillation
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arXiv:2510.06562v4 Announce Type: replace Abstract: We present a distilled multi-time-step (DMTS) strategy to accelerate molecular dynamics simulations using foundation neural network models. DMTS uses a dual-level neural network where the target accurate potential is coupled to a simpler but faster model obtained via a distillation process. The 3.5 \r{A}-cutoff distilled model is sufficient to capture the fast-varying forces, i.e., mainly bonded interactions, from the accurate potential allowing its use in a reversible reference system propagator algorithms (RESPA)-like formalism. The approach conserves accuracy, preserving both static and dynamical properties, while enabling to evaluate the costly model only every 3 to 6 fs depending on the system. Consequently, large simulation speedups over standard 1 fs integration are observed: nearly 4-fold in homogeneous systems and 3-fold in large solvated proteins through leveraging active learning for enhanced stability. Such a strategy is applicable to any neural network potential and reduces their performance gap with classical force fields.
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https://arxiv.org/abs/2510.06562
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d1afb519c9e37a43d5a62397d40e33f63eafa95151f88dd3e23a41c87d32e7f6
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2026-01-13T00:00:00-05:00
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Learning constitutive models and rheology from partial flow measurements
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arXiv:2510.24673v2 Announce Type: replace Abstract: Constitutive laws are at the core of fluid mechanics, relating the fluid stress to its deformation rate. Unlike Newtonian fluids, most industrial and biological fluids are non-Newtonian, exhibiting a nonlinear relation. Accurately characterizing this nonlinearity is essential for predicting flow behavior in real-world engineering and translational applications. Yet current methods fall short by relying on bulk rheometer data and simple fits that fail to capture behaviors relevant in complex geometries and flow conditions. Data-driven approaches can capture more complex behaviors, but lack interpretability or consistency. To close this gap, we leverage automatic differentiation to build an end-to-end framework for robust rheological learning. We develop a differentiable non-Newtonian fluid solver with a frame-invariant tensor basis neural network closure that learns stress directly from arbitrary flow measurements, such as velocimetry data. In parallel, we implement differentiable versions of major constitutive relations, enabling Bayesian model parametrization and selection from rheometer data. Our framework predicts flows in unseen geometries and ensures physical consistency and interpretability by matching neural network responses to known constitutive laws. Ultimately, this work lays the groundwork for advanced digital rheometry capable of comprehensively characterizing non-Newtonian and viscoelastic fluids under realistic in-situ or in-line operating conditions.
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https://arxiv.org/abs/2510.24673
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0a5eb6db233ffcd8b7c832d71667d647c3f935123be75f4b0fbce8148a6d7c86
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Efficient calculation of magnetic fields from ferromagnetic materials near strong electromagnets, and application to stellarator coil optimization
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arXiv:2511.17305v2 Announce Type: replace Abstract: In fusion reactor design, steels under consideration for the blanket are ferromagnetic, so the steel's effect on the plasma physics must be examined. For efficient calculation of these fields, we can exploit the fact that the magnetic material gives a small perturbation relative to the fields from the electromagnetic coils and plasma. Moreover the magnetization is saturated due to the strong fields in typical fusion systems. These approximations significantly reduce the nonlinearity of the problem, so the magnetic materials can be described by an array of point dipoles of known magnitude, oriented in the direction of the coil and plasma field. The approach is verified by comparison to finite-element calculations with commercial software and shown to be accurate. As no linear or nonlinear solve is required, only evaluation of Biot-Savart-type integrals, the method here is significantly simpler to implement than other methods, and extremely fast. The method is compatible with arbitrary CAD geometry, and also allows rapid computation of the magnetic forces. We demonstrate adding the ferromagnetic effects to free-boundary MHD equilibrium calculations, assessing the effect on plasma properties such as confinement and stability. Moreover, it is straightforward to differentiate through the model to get the derivative of the field with respect to the electromagnet parameters. We thereby demonstrate gradient-based coil optimization for a quasi-isodynamic stellarator in which the field contribution from a ferromagnetic blanket is included. Even a significant steel volume is found to have little impact on the plasma physics properties, with the main effects being a slight destabilization of ballooning modes and a radial shift of the edge islands due to decrease in rotational transform. Both issues are corrected by minor reoptimization of the coil shapes to account for the field from the steel.
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https://arxiv.org/abs/2511.17305
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1e383221f3beef5947100b64d2ed7c653d27a1b011a52bdad1fb121aa960cb73
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2026-01-13T00:00:00-05:00
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A primer on treatment planning aspects for temporally modulated pulsed radiation therapy
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arXiv:2511.19329v2 Announce Type: replace Abstract: Temporally modulated pulsed radiotherapy (TMPRT) delivers conventional fraction doses of radiation using temporally separated pulses of low doses (<30 cGy) yielding fraction-effective dose rates of around 6.7 cGy/min with the goal to exploit tumor radiation hypersensitivity, which was observed in both, preclinical models and in human clinical trials. To facilitate TMPRT, volumetric modulated arc therapy (VMAT) and 3D-CRT planning techniques were developed following the guidelines of the proposed NRG CC-017 trial. Plans were evaluated with respect to homogeneity, conformality, and adherence to dose constraints. Deliverability of plans was assessed using in-phantom measurements for absorbed dose accuracy at low dose rates and using EPID for isodose verification. For VMAT only single arc plans were found to be acceptable due to otherwise unacceptably heterogeneous field doses, while for dynamic conformal arcs machine limtations on the number of monitor units per degree require the use of partial arcs for each pulse. Delivery of plans at low dose rates (< 100 MU/min) was accurate with high Gamma pass rates on modern LINACs and moderate pass rates on legacy LINACs, in line with their general performance. Generally, VMAT is preferred to achieve optimal homogeneity, conformality, and organ-at-risk sparing, while the use of 3D-CRT can increase the availability of TMPRT for more patients and clinics.
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https://arxiv.org/abs/2511.19329
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fbbbdfaffbd2b1aeed156ea0619c417221082ad5a4e4dc87c7dd11024ac2edce
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2026-01-13T00:00:00-05:00
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Multilayer network science: theory, methods, and applications
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arXiv:2511.23371v2 Announce Type: replace Abstract: Multilayer network science has emerged as a central framework for analysing interconnected and interdependent complex systems. Its relevance has grown substantially with the increasing availability of rich, heterogeneous data, which makes it possible to uncover and exploit the inherently multilayered organisation of many real-world networks. In this review, we summarise recent developments in the field. On the theoretical and methodological front, we outline core concepts and survey advances in community detection, dynamical processes, temporal networks, higher-order interactions, and machine-learning-based approaches. On the application side, we discuss progress across diverse domains, including interdependent infrastructures, spreading dynamics, computational social science, economic and financial systems, ecological and climate networks, science-of-science studies, network medicine, and network neuroscience. We conclude with a forward-looking perspective, emphasizing the need for standardized datasets and software, deeper integration of temporal and higher-order structures, and a transition toward genuinely predictive models of complex systems.
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https://arxiv.org/abs/2511.23371
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add59bebe2aee41f27b5f1a7a51b1a03f2c34b798f573b2ec606ae896311b509
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2026-01-13T00:00:00-05:00
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Sub-second A-scan Acquisition Using Marginal Spectral-Domain Quantum Optical Coherence Tomography
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arXiv:2512.01110v2 Announce Type: replace Abstract: We report an optimized implementation of spectral-domain quantum optical coherence tomography (SD-QOCT) capable of acquiring axial scans (A-scans) of multilayer samples without in the absence of mechanical scanning, at an unprecedented speed. We demonstrate a proof-of-concept system that integrates a diffraction grating, a high-resolution intensified CCD camera, and a high-flux photon-pair source operating in the VIS-NIR region (810 nm). This configuration enables the acquisition of an entire marginal SD-QOCT interferogram in a single camera exposure, yielding a transverse A-scan with a record acquisition time of 100 ms and a penetration depth of 4 mm. The measured interferometric response shows excellent agreement with the theoretical model. These results represent a decisive step toward the practical deployment of SD-QOCT as a competitive imaging modality for biomedical applications.
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https://arxiv.org/abs/2512.01110
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d9b00368e8bc6b857ae7bcf75c6db62d883036241470033ccb5036307afe2988
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2026-01-13T00:00:00-05:00
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Terahertz emission from interdigitated photoconductive antennas based on Ge-on-Si
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arXiv:2512.03820v2 Announce Type: replace Abstract: An interdigitated photoconductive antenna (i-PCA) for terahertz (THz) emission with a novel metal-insulator-semiconductor interface is designed with the aim of developing compact and scalable THz devices. The photoconductive material is an amorphous germanium (Ge) film deposited using DC magnetron sputtering. The antenna electrodes are composed of gold-germanium (AuGe). With the integration of a silicon dioxide (SiO2) layer that acts as an electrical mask on alternate active areas, we present a simple approach to fabricate a large-area i-PCA. Along with a simplified fabrication compared to other existing designs, our approach increases the electrical robustness of the emitter and reduces the inactive gap area on the device. The i-PCA is capable of THz emission up to 2.5 THz and 36 dB signal-to-noise ratio (SNR), and is promising for applications in CMOS technologies.
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https://arxiv.org/abs/2512.03820
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e4923c64a2163314895dda1755c22cc9f546fd362122eea60f4aad75ff355d14
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2026-01-13T00:00:00-05:00
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Comment on "Monochromatization interaction region optics design for direct s-channel Higgs production at FCC-ee"
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arXiv:2512.03997v2 Announce Type: replace Abstract: The original article [1] can be logically divided into two parts: 1) the selection of main parameters for monochromatization and 2) interaction region optics design; the comment pertains only to the first part. The authors of [1] state that "The purpose of this paper is to report on the development of realistic IR optics designs for monochromatization at the FCC-ee". However, the proposed parameters do not seem very realistic and raise many questions; due to space limitations, we will only consider the most important ones.
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https://arxiv.org/abs/2512.03997
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f5aaca84e898ca4d57ec7d7dfb2f53db71acba3e50a36818d6029904766f8591
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2026-01-13T00:00:00-05:00
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Using Open Source EDA Tools in ASICs for HEP: A Mixed Comparison
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arXiv:2512.06122v3 Announce Type: replace Abstract: This work compares open-source electronic design automation tools with a commercial environment using three representative integrated circuit blocks in the IHP 130 nm open PDK: a common-mode noise filter, a finite-state machine, and a voltage-controlled oscillator. The study reports design effort and quality of results for digital logic, including area, power, and timing closure, and examines analog layout feasibility. For the finite-state machine at 50 MHz, the open-source flow reached 0.029 mm$^2$ (post-layout) and 4.37 mW (estimated) with 828 standard cells, whereas the commercial flow achieved 0.019 mm$^2$ and 2.00 mW with 497 cells, corresponding to increases of 53\% in area and 118\% in power. The common-mode noise filter totals 1.879 mm$^2$ with 1703 flip-flops at 50 MHz. The voltage-controlled oscillator occupies 0.0025 mm$^2$ and achieves a simulated maximum oscillation frequency of 2.65 GHz. The contribution is a side-by-side quantification of quality of results across digital and analog blocks in the IHP open PDK. The results indicate that open-source tools are viable for early prototyping, training, and collaboration, while commercial flows retain advantages in automation and quality of results when strict targets on power and area or precision analog layout are required.
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https://arxiv.org/abs/2512.06122
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2026-01-13T00:00:00-05:00
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Determinism and Indeterminism as Model Artefacts: Toward a Model-Invariant Ontology of Physics
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arXiv:2512.22540v2 Announce Type: replace Abstract: This paper argues that the traditional opposition between determinism and indeterminism in physics is representational rather than ontological. Deterministic-stochastic dualities are available in principle, and arise in a non-contrived way in many scientifically important models. When dynamical systems admit mathematically equivalent deterministic and stochastic formulations, their observable predictions depend only on the induced structure of correlations between preparations and measurement outcomes. I use this model-equivalence to motivate a model-invariance criterion for ontological commitment, according to which only structural features that remain stable across empirically equivalent representations, and whose physical effects are invariant under such reformulations, are candidates for realism. This yields a fallibilist form of structural realism grounded in modal robustness rather than in the specifics of any given mathematical representation. Features such as conservation laws, symmetries, and causal or metric structure satisfy this criterion and can be encoded in observable relations in mathematically intelligible ways. By contrast, the localisation of modal selection -- whether in initial conditions, stochastic outcomes, or informational collapse mechanisms -- is not invariant under empirically equivalent reformulations and is therefore best understood as a gauge choice rather than an ontological feature. The resulting framework explains how certain long-standing problems in the foundations of physics, including the measurement problem and the perceived conflict between physical determinism and free agency, arise from the reification of representational artefacts. By distinguishing model-invariant structure from modelling conventions, I offer a realist ontology for modern physics that combines empirical openness with resistance to metaphysical overreach.
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https://arxiv.org/abs/2512.22540
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13a5e3a5abd9a920935b7e6f089d24684f867ba1ea3d41dce54dcf0554466a86
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2026-01-13T00:00:00-05:00
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First-Return Statistics in Henyey-Greenstein Scattering: Colored Motzkin Polynomials and the Cauchy Kernel
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arXiv:2601.00173v4 Announce Type: replace Abstract: We show that first-return statistics in three-dimensional Henyey Greenstein scattering require a Boundary Truncation Factor (BTF) that takes a Cauchy kernel form. In our previous work (6), we established that first-return probabilities in 1D scattering expand in Catalan and Motzkin numbers. Extending this to 3D anisotropic scattering requires a BTF that, as Monte Carlo reveals, follows a Cauchy kernel:
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https://arxiv.org/abs/2601.00173
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5c814ed08e48aa6d7b5ae79ee257de199425db933234027e93f4bacb669eb3a3
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2026-01-13T00:00:00-05:00
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Elaboration on the kinetic approach of Derbenev and Kondratenko to spin-polarized beams in electron storage rings
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arXiv:2601.00586v2 Announce Type: replace Abstract: We present a detailed account of the kinetic approach for describing the effect of synchrotron radiation on electron and positron spin polarization in storage rings. This approach was introduced in 1974 by Derbenev and Kondratenko and was extended by us since 2001. The kinetic approach is much less frequently utilized but it is more general than the original non-kinetic approach of Derbenev and Kondratenko from 1972 since the kinetic approach is not centered on the invariant spin field. As with the non-kinetic approach the kinetic approach covers the radiative depolarization effect, the Sokolov-Ternov effect and its Baier-Katkov correction as well as the kinetic polarization effect but it enables the calculation of corrections to the original Derbenev-Kondratenko formulas and thereby provides estimates of the reliability of the latter. The kinetic appoach is applicable to storage rings with energies from a few GeV up to the energies of the FCC-ee and CEPC and beyond. The kinetic approach is based on the spin-orbit Wigner functions which lead to the so-called Bloch equation for the polarization density which is a generalization of Fokker-Planck equations to spin motion. In turn, as discovered in 2019, the Bloch equation is based on stochastic ordinary differential equations which can be used to develop Monte-Carlo spin-tracking codes covering the key effects beyond just radiative depolarization. These stochastic ordinary differential equations lead to a new viewpoint of the physical effects, in particular the kinetic polarization effect.
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https://arxiv.org/abs/2601.00586
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e4407d8cea78c51939fec356d094fd483677a592de12ed35341decab0ebb7b4d
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2026-01-13T00:00:00-05:00
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Liouville Spectral Gap and Bifurcation Driven Lagrangian Eulerian Decoupling with Nondiffusive Turbulence Closures
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arXiv:2601.02268v2 Announce Type: replace Abstract: In fully developed homogeneous and isotropic turbulence, the Lagrangian and Eulerian descriptions of motion, although formally equivalent, become statistically decoupled. In this work, by invoking Liouville theorem, we show that the joint probability density function (PDF) of the Eulerian and Lagrangian fields, evolving from arbitrary initial conditions, relaxes exponentially toward a factorized form given by the product of the corresponding marginal PDFs. This relaxation is governed by a genuine spectral gap of the Liouville operator, whose magnitude is primarily set by the bifurcation rate of the velocity gradient dynamics, whereas the contribution of Lyapunov exponents is shown to be significantly smaller. As a consequence, Eulerian Lagrangian correlations decay rapidly, and if the joint PDF is initially factorized, its factorized structure is preserved at all subsequent times, with each marginal evolving independently under the corresponding dynamics. We further show that the formal equivalence between the two descriptions implies the invariance of the relative kinetic energy between arbitrarily chosen points. When combined with the asymmetric statistics of instantaneous finite scale Lyapunov exponents in incompressible turbulence, this property provides a quantitative interpretation of particle pair separation and of the turbulent energy cascade. Finally, these results naturally lead to nondiffusive closure relations for the von K\'arm\'an Howarth and Corrsin equations, which coincide with those previously proposed by the author, thereby providing an independent theoretical validation of those closures.
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https://arxiv.org/abs/2601.02268
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bbfd82b7d1dc799a9271357a1a3f225f57dde0da1c8fe1c143bd61e85c8f0a44
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2026-01-13T00:00:00-05:00
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Microscopy system for in situ sea ice structure and biology observations
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arXiv:2601.02328v3 Announce Type: replace Abstract: Sea ice harbours a rich community of well-adapted microorganisms that inhabit liquid micro-spaces where extreme conditions prevail. Currently at risk under climate change, the sea-ice microbiome holds mysteries about evolution of life on Earth and possibly elsewhere, which require methodological innovation to be unravelled. Gaining microscopic insight into the internal structure and biology of sea ice has traditionally been limited to destructive and extrusive ice core sampling methods. Here we present an in situ microscopic imaging system to observe undisturbed living microorganisms directly within sea the ice matrix. The complex and heterogeneous nature of sea ice, including its water crystal lattice, brine channels, air bubbles, and various impurities, presents engineering challenges for the development of this imaging system. Despite the fragile nature of the sea-ice matrix, we could successfully deploy, test and use the new in situ microscope during a recent expedition on the icepack in Arctic. We collected numerous images of live and intact single-celled and colony-forming diatoms, and documented for the first time at such a high resolution some microphysical features of sea ice. The hardware and software design of the endoscope is presented along with acquisition results of the microstructure and diatom images. These findings collectively demonstrate the potential for this new in situ microscopic imaging system to transform the way we study sea ice and to allow a deeper understanding of its complex microstructure and living microorganisms.
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https://arxiv.org/abs/2601.02328
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0a5ae53f45731e15abd39c6ebe3e28188b76d73db961e071f01ea235a8808191
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2026-01-13T00:00:00-05:00
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Finding Graph Isomorphisms in Heated Spaces in Almost No Time
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arXiv:2601.03787v2 Announce Type: replace Abstract: Determining whether two graphs are structurally identical is a fundamental problem with applications spanning mathematics, computer science, chemistry, and network science. Despite decades of study, graph isomorphism remains a challenging algorithmic task, particularly for highly symmetric structures. Here we introduce a new algorithmic approach based on ideas from spectral graph theory and geometry that constructs candidate correspondences between vertices using their curvatures. Any correspondence produced by the algorithm is explicitly verified, ensuring that non-isomorphic graphs are never incorrectly identified as isomorphic. Although the method does not yet guarantee success on all isomorphic inputs, we find that it correctly resolves every instance tested in deterministic polynomial time, including a broad collection of graphs known to be difficult for classical spectral techniques. These results demonstrate that enriched spectral methods can be far more powerful than previously understood, and suggest a promising direction for the practical resolution of the complexity of the graph isomorphism problem.
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https://arxiv.org/abs/2601.03787
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Academic Papers
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d68833e8cb522356795baa0ce989f0341597eed11ef0aa49a64aa6d1ae537db2
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2026-01-13T00:00:00-05:00
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Wakefield Acceleration in a Layered Plasma Waveguide
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arXiv:2601.04903v2 Announce Type: replace Abstract: Plasma wakefield accelerators (PWFA) represent one of the promising new accelerator concepts that are now being developed intensively for future applications in high-energy physics and industry. Among the unresolved problems of practical implementation of PWFA there are maintaining the required quality (emittance, size, energy spread of bunches) and stable transportation of drive and accelerated (witness) bunches over long acceleration distances. For improving the bunch transport, we propose to fill the bunch transport channel with the background plasma, the density of which is lower than the main plasma density building up an accelerating wake wave. We call this waveguide structure a layered plasma waveguide (LPW). The wakefield excitation by a regular sequence of electron bunches in the LPW of cylindrical configuration has been explored both analytically and numerically. The layered plasma has been modeled as a combination of a tubular plasma and a plasma column of significantly different densities. The plasma column has a lower density. The dispersion dependencies of the TM-modes of the LPW was obtained and analyzed, and it was found that there was a single TM wave resonant with the electron bunch. Based on the obtained analytical expressions, the structures of the axial and radial wakefield amplitudes have been numerically investigated for the cases of a single drive bunch and a regular train of bunches. It is shown that for certain density ratios of the outer and inner plasmas, it is possible both to accelerate and focus simultaneously the drive and witness bunches. The 2.5D particle-in-cell code was used to simulate the witness acceleration of an electron bunch by a wakefield created by drive electron bunches in a two-layer plasma wakefield accelerator. The simulation showed good agreement with the results of analytical calculations.
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https://arxiv.org/abs/2601.04903
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Academic Papers
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c50c52079215350033a9c7fe7c142b134fd0918a9b1abf310c1db6c5730af9d4
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2026-01-13T00:00:00-05:00
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Machine learning for radiative hydrodynamics in astrophysics
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arXiv:2601.05155v2 Announce Type: replace Abstract: Radiation hydrodynamics describes the interaction between high-temperature hypersonic plasmas and the radiation they emit or absorb, a coupling that plays a central role in many astrophysical phenomena related to accretion and ejection processes. The HADES code was developed to model such systems by coupling hydrodynamics with M1-gray or M1-multigroup radiative transfer models, which are well suited to optically intermediate media. Despite its accuracy, radiation hydrodynamics simulations remain extremely demanding in terms of computational cost. Two main limitations are responsible for this. First, the M1-multigroup model relies on a closure relation with no analytic expression, requiring expensive numerical evaluations. Second, the Courant-Friedrichs-Lewy condition strongly restricts the time step of the explicit schemes used in HADES. To overcome these difficulties, two complementary Artificial Intelligence based strategies were developed in this thesis. The first approach consists in training a Multi-Layer Perceptron to approximate the M1-multigroup closure relation. This method achieves excellent accuracy while reducing the computational cost by a factor of 3000, making it the most efficient approach currently available for this task. This performance gain enables high-fidelity simulations of radiative shocks, in which radiation directly influences the shock structure. In particular, increasing spectral resolution slows down the shock and enlarges the radiative precursor. The second approach explores the use of Physics-Informed Neural Networks to directly solve the radiation hydrodynamics equations and extrapolate simulations beyond their initial time range. Tests on purely hydrodynamic shocks show accurate handling of discontinuities, but application to radiative shocks remains challenging and requires further investigation.
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https://arxiv.org/abs/2601.05155
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Academic Papers
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b344f6a1e388ced0ffb7cee6524f43037091a9858d95c1e779cc23c8cc009bf1
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2026-01-13T00:00:00-05:00
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Optical Entropy and Generalized Thermodynamics of Solitonic Event Horizons
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arXiv:2601.05156v2 Announce Type: replace Abstract: The realization of Hawking radiation in optical analogs has historically focused on kinematic observables, such as the effective temperature determined by the horizon's surface gravity. A complete thermodynamic description, however, necessitates a rigorous definition of entropy and irreversibility, which has remained elusive in Hamiltonian optical systems. In this work, we bridge this gap by introducing an operational entropy for solitonic event horizons, derived from the spectral partitioning of the optical field into coherent solitonic and incoherent radiative subsystems. We demonstrate that the emission of resonant radiation, mediated by the breaking of soliton integrability due to higher-order dispersion, serves as a fundamental mechanism for entropy production. Numerical simulations of the generalized nonlinear Schrodinger equation confirm that this process satisfies a generalized second law, where the change in total entropy is non-negative. These results establish optical event horizons as consistent nonequilibrium thermodynamic systems, offering a new pathway to explore the information-theoretic aspects of analog gravity in laboratory settings.
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https://arxiv.org/abs/2601.05156
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Academic Papers
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ee896a626ea233d57ded0112fd32737c987e9a4de207c0b4193d27e64b5c57b8
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2026-01-13T00:00:00-05:00
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Vicsek Model Meets DBSCAN: Cluster Phases in the Vicsek Model
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arXiv:2307.12538v3 Announce Type: replace-cross Abstract: The Vicsek model, which was originally proposed to explain the dynamics of bird flocking, exhibits a phase transition with respect to the absolute value of the mean velocity. Although clusters of agents can be easily observed via numerical simulations of the Vicsek model, qualitative studies are lacking. We study the clustering structure of the Vicsek model by applying DBSCAN, a recently-introduced clustering algorithm, and report that the Vicsek model shows a phase transition with respect to the number of clusters: from O(N) to O(1), with N being the number of agents, when increasing the magnitude of noise for a fixed radius that specifies the interaction of the Vicsek model. We also report that the combination of the order parameter proposed by Vicsek et al. and the number of clusters defines at least four phases of the Vicsek model.
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https://arxiv.org/abs/2307.12538
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Academic Papers
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ad703a0bcf3fc98895323a3f2cd1641c2cd87c668fadd2f42a95a331377994ee
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2026-01-13T00:00:00-05:00
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Neuromorphic Photonic Computing with an Electro-Optic Analog Memory
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arXiv:2401.16515v5 Announce Type: replace-cross Abstract: In neuromorphic photonic systems, device operations are typically governed by analog signals, necessitating digital-to-analog converters (DAC) and analog-to-digital converters (ADC). However, data movement between memory and these converters in conventional von Neumann architectures incur significant energy costs. We propose an analog electronic memory co-located with photonic computing units to eliminate repeated long-distance data movement. Here, we demonstrate a monolithically integrated neuromorphic photonic circuit with on-chip capacitive analog memory and evaluate its performance in machine learning for in situ training and inference using the MNIST dataset. Our analysis shows that integrating analog memory into a neuromorphic photonic architecture can achieve over 26x power savings compared to conventional SRAM-DAC architectures. Furthermore, maintaining a minimum analog memory retention-to-network-latency ratio of 100 maintains >90% inference accuracy, enabling leaky analog memories without substantial performance degradation. This approach reduces reliance on DACs, minimizes data movement, and offers a scalable pathway toward energy-efficient, high-speed neuromorphic photonic computing.
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https://arxiv.org/abs/2401.16515
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Academic Papers
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30d9f7b0bd61229abb357024540a8da328e08a1fddf528b5c382fa0665d660c3
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2026-01-13T00:00:00-05:00
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Hierarchic Flows to Estimate and Sample High-dimensional Probabilities
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arXiv:2405.03468v2 Announce Type: replace-cross Abstract: Finding low-dimensional interpretable models of complex physical fields such as turbulence remains an open question, 80 years after the pioneer work of Kolmogorov. Estimating high-dimensional probability distributions from data samples suffers from an optimization and an approximation curse of dimensionality. It may be avoided by following a hierarchic probability flow from coarse to fine scales. This inverse renormalization group is defined by conditional probabilities across scales, renormalized in a wavelet basis. For a $\vvarphi^4$ scalar potential, sampling these hierarchic models avoids the critical slowing down at the phase transition. In a well chosen wavelet basis, conditional probabilities can be captured with low dimensional parametric models, because interactions between wavelet coefficients are local in space and scales. An outstanding issue is also to approximate non-Gaussian fields having long-range interactions in space and across scales. We introduce low-dimensional models of wavelet conditional probabilities with the scattering covariance. It is calculated with a second wavelet transform, which defines interactions over two hierarchies of scales. We estimate and sample these wavelet scattering models to generate 2D vorticity fields of turbulence, and images of dark matter densities.
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https://arxiv.org/abs/2405.03468
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Academic Papers
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5eaf5e8df2f2fbe50cc172eb3d3b3159a5d22e7f93381a8e9b94fc7fd06c770c
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2026-01-13T00:00:00-05:00
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Revisiting superradiance dynamics from single diamond nanocrystals with a physically consistent model for fluorescence decay
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arXiv:2409.07461v2 Announce Type: replace-cross Abstract: The paper by C. Bradac et al. [Nat. Commun. 8, 1205 (2017)] discusses room-temperature superradiance from NV color centers in diamonds. It presents a new model intended to reflect experimental characteristics of this phenomenon. To validate the model, the authors provide experimental results that are subsequently compared with numerical calculations derived from the scheme. Motivated by our own experiments with the fluorescence of similar NV samples, we attempted to create a theoretical model to accurately describe experimental systems. Initially, we aimed to incorporate the numerical equations from Bradac et al.'s paper's supplement into our own theoretical framework. However, we encountered numerous issues resulting in non-physical results such as negative photon counts or non-zero asymptotic fluorescence intensity. We identified these inconsistencies and proposed amendments to rectify them. We have developed our own framework by correctly reinterpreting the terms of the master equation. The resulting formulas produce physically meaningful results consistent with experimental data.
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https://arxiv.org/abs/2409.07461
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Academic Papers
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svg
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853d14e6be0fa6617b1a59b32b9588097eb1d0292d972cdb9b2b4bb051b50eb9
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2026-01-13T00:00:00-05:00
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An information-matching approach to optimal experimental design and active learning
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arXiv:2411.02740v4 Announce Type: replace-cross Abstract: The efficacy of mathematical models heavily depends on the quality of the training data, yet collecting sufficient data is often expensive and challenging. Many modeling applications require inferring parameters only as a means to predict other quantities of interest (QoI). Because models often contain many unidentifiable (sloppy) parameters, QoIs often depend on a relatively small number of parameter combinations. Therefore, we introduce an information-matching criterion based on the Fisher Information Matrix to select the most informative training data from a candidate pool. This method ensures that the selected data contain sufficient information to learn only those parameters that are needed to constrain downstream QoIs. It is formulated as a convex optimization problem, making it scalable to large models and datasets. We demonstrate the effectiveness of this approach across various modeling problems in diverse scientific fields, including power systems and underwater acoustics. Finally, we use information-matching as a query function within an Active Learning loop for material science applications. In all these applications, we find that a relatively small set of optimal training data can provide the necessary information for achieving precise predictions. These results are encouraging for diverse future applications, particularly active learning in large machine learning models.
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https://arxiv.org/abs/2411.02740
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Academic Papers
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fc3de9b5cacabec0a3ade559b8bf3a94f8b91d069d96cebdbd25c55c3faa8da3
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2026-01-13T00:00:00-05:00
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Demonstrating Electrochemical CO$_2$ Capture on Redox-Active Metal-Organic Frameworks
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arXiv:2411.16444v3 Announce Type: replace-cross Abstract: Addressing climate change calls for action to control CO$_2$ pollution. Direct air and ocean capture offer a solution to this challenge. Making carbon capture competitive with alternatives, such as forestation and mineralisation, requires fundamentally novel approaches and ideas. One such approach is electrosorption, which is currently limited by the availability of suitable electrosorbents. In this work, we introduce a metal-organic copper-2,3,6,7,10,11-hexahydroxytriphenylene (Cu$_3$(HHTP)$_2$) metal-organic framework (MOF) that can act as electrosorbent for CO$_2$ capture, thereby expanding the palette of materials that can be used for this process. Cu$_3$(HHTP)$_2$ is the first MOF to switch its ability to capture and release CO$_2$ in aqueous electrolytes. By using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), galvanostatic charge-discharge (GCD) analysis, and differential electrochemical mass spectrometry (DEMS), we demonstrate reversible CO$_2$ electrosorption. Based on density functional theory (DFT) calculations, we provide atomistic insights into the mechanism of electrosorption and conclude that efficient CO$_2$ capture is facilitated by a combination of redox-active copper atom and aromatic HHTP ligand within Cu3(HHTP)2. By showcasing the applicability of Cu$_3$(HHTP)$_2$ -- with a CO$_2$ capacity of 2 mmol g$^{-1}$ and an adsorption enthalpy of -20 kJ mol$^{-1}$ - this study encourages further exploration of conductive redox-active MOFs in the search for superior CO$_2$ electrosorbents.
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https://arxiv.org/abs/2411.16444
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Academic Papers
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cd2a28115d01e9ff197a035a25d4479cdaaccd8819fff7a3cf4e5c84e85a3f37
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2026-01-13T00:00:00-05:00
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Three-dimensional quantum anomalous Hall effect in Weyl semimetals
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arXiv:2501.01399v2 Announce Type: replace-cross Abstract: The quantum anomalous Hall effect (QAHE) is a quantum phenomenon in which a two-dimensional system exhibits a quantized Hall resistance $h/e^2$ in the absence of magnetic field, where $h$ is the Planck constant and $e$ is the electron charge. In this work, we extend this novel phase to three dimensions and thus propose a three-dimensional QAHE exhibiting richer and more versatile transport behaviors. We first confirm this three-dimensional QAHE through the quantized Chern number, then establish its bulk-boundary correspondence, and finally reaffirm it via the distinctive transport properties. Remarkably, we find that the three-dimensional QAHE hosts two chiral surface states along one spatial direction while a pair of chiral hinge states along another direction, and the location of the hinge states depends sensitively on the Fermi energy. These two types of boundary states are further connected through a perpendicular chiral surface states, whose chirality is also Fermi energy dependent. Consequently, depending on the transport direction, its Hall resistance can quantize to $0$, $h/e^2$, or $\pm h/e^2$ when the Fermi energy is tuned across the charge neutral point. This three-dimensional QAHE not only fill the gap in the Hall effect family but also holds significant potentials in device applications such as in-memory computing.
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https://arxiv.org/abs/2501.01399
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Academic Papers
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svg
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5192007a6ce62b4b00bbd20bde9391cb36cfed70e3d8ba1ae0aacb89f0632bdc
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2026-01-13T00:00:00-05:00
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Metasurfaces-Enabled Wave Computing for Future Wireless Systems: Opportunities and Challenges
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arXiv:2501.05173v2 Announce Type: replace-cross Abstract: The next generations of wireless networks are envisioned to integrate communications, sensing, and computing into a unified platform, demanding ultra-high data rates, submillisecond latency, and unprecedented energy efficiency. However, conventional digital processors face limitations in scalability, cost, and power consumption that hinder this vision. Wave computing, enabled by programmable metasurfaces, offers an alternative paradigm according to which signal processing operations are implemented in the domain of the propagation of electromagnetic waves. This approach transforms metasurfaces from passive wavefront shapers into functional analog processors capable of executing tasks such as beamforming, sensing, imaging, and machine learning at the speed of light with minimal power consumption. This article provides an overview of metasurface-enabled wave computing, highlighting its fundamental principles and key application scenarios for future wireless systems, including integrated sensing and communications, artificial intelligence acceleration, over-the-air channel estimation, and computational electromagnetic imaging. Future research directions are outlined in response to the major open challenges of the technology, aiming to enable large-scale deployment of wave computing in practical wireless networks.
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https://arxiv.org/abs/2501.05173
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Academic Papers
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