We model the time evolution of single win odds in Japanese horse racing as a stochastic process, deriving an Ornstein--Uhlenbeck process by analyzing the probability dynamics of vote shares and the empirical time series of odds movements. Our framework incorporates two types of bettors: herders, who adjust their bets based on current odds, and fundamentalists, who wager based on a horse's true winning probability. Using data from 3450 Japan Racing Association races in 2008, we identify a microscopic probability rule governing individual bets and a mean-reverting macroscopic pattern in odds convergence. This structure parallels financial markets, where traders' decisions are influenced by market fluctuations, and the interplay between herding and fundamentalist strategies shapes price dynamics. These results highlight the broader applicability of our approach to non-equilibrium financial and betting markets, where mean-reverting dynamics emerge from simple behavioral interactions.
Current research funding systems are subject to structural imbalances, where formal criteria such as the H-index and the number of publications dominate over the potential and actual scientific prospects of researchers. This leads to the suppression of potential breakthrough research directions and limited access to grants for stochastic (innovative) researchers. In this paper, we propose a dynamic agent-based model of research grant redistribution that takes into account the adaptive mechanism of funding redistribution on the basis of the quality of stochastic research. The simulation was conducted on a sample of 21,534 Kazakhstani researchers with 30 iterations, during which the growth of the formal features of stochastic scientists was analyzed under different grant distribution scenarios. A grant redistribution parameter {\lambda} was introduced, which controls adaptive funding. The results showed that at {\lambda}=0.15, stochastic scientists begin to catch up with formal scientists in terms of productivity without destabilizing the scientific system. On the basis of the data obtained, a principle called the Haderach principle was proposed. It consists of a dynamic balance between formal (stable) and stochastic (informal) science. The developed approach can be used to optimize grant systems, allowing the elimination of barriers to new scientific directions and potential achievements without losing the stability of traditional schools. New concepts and terms of scientific vocabulary are introduced: the Haderach principle, excluded science, supplemented science, grant monopoly, and so on. Article structured V new IRPAS (Induction, Related Works, Processing, Analysis, Synthesis) notations.
This study proposes a new approach to the interpretation of Greek Doric-style temples, based on the integration of its tangible and intangible dimensions as a cultural heritage asset. Rooted on the Greek concept of techne, the work considers a unifying design principle, integrating both structural and functional aspects within the architectural style. A multidisciplinary perspective was adopted, combining archaeological, documentary, and metrological analysis of 41 Doric temples from the 6th to the 4th century BC, located in Greece and Magna Graecia. Starting from the evidence of a statistical correlation among key geometric parameters, these quantitative data are re-interpreted through a geometrical physics vibroacoustic model. The results demonstrate that structural elements act as acoustic attenuators, minimizing environmental forces (particularly wind) on the temple cell's walls. The study also suggests that slight deviations from the classic East-West orientation were adopted to reduce the acoustic coupling with prevailing local winds. The Archaeological Park of Paestum (Salerno, Italy) provides significant evidence for this hypothesis, as its temples, despite their different construction periods, share a consistent orientation, distinct from the city's street grid. These findings contribute to a deeper understanding of Greek know-how, being a part of the intangible dimension of cultural heritage and traditional ecological knowledge related to the architectural design in relation to the environmental factors.
In this paper, we examine the wide-ranging impact of artificial intelligence on society, focusing on its potential to both help and harm global equity, cognitive abilities, and economic stability. We argue that while artificial intelligence offers significant opportunities for progress in areas like healthcare, education, and scientific research, its rapid growth -- mainly driven by private companies -- may worsen global inequalities, increase dependence on automated systems for cognitive tasks, and disrupt established economic paradigms. We emphasize the critical need for strong governance and ethical guidelines to tackle these issues, urging the academic community to actively participate in creating policies that ensure the benefits of artificial intelligence are shared fairly and its risks are managed effectively.
In the paper, in the scattering problem for the valence electron model potential a self-adjoint extension is performed and Rutherford formula is modified. The scattering of slow particles for this potential is also discussed and the changes caused by the self-adjoint extension in the differential and integral cross-sections of the scattering are studied.
Lecture notes for a one-semester master-level course on analytical mechanics and classical field theory, covering: 0 Mathematical Introduction, 1 Lagrangian Mechanics, 2 Application: Motion in Central Fields, 3 Hamiltonian Mechanics, 4 Application: Oscillations of Mechanical Systems, 5 Application: Relativistic Mechanics, 6 Geometry of Classical Mechanics, 7 Application: Dynamics of Rigid Bodies, 8 Lagrangian and Hamiltonian Mechanics of Continuous Systems, 9 Application: Elasticity of Solids, 10 Symmetries and Conservation Laws, 11 Application: Fluid Dynamics, 12 Application: Electrodynamics
Aim. Implement a stochastic representation of the wave function for a pair of entangled soliton functions in a liquid crystal. Show the applicability of a special soliton representation of quantum mechanics for modeling real entangled systems. Methodology. The central place in the study is occupied by the method of mathematical modeling. As part of the calculation of stochastics by the method of abstraction and concretization, a detailed mathematical apparatus is given, adapted to the real physical case. A qualitative analysis of the behavior of the material during the propagation of soliton pulses in it is carried out. Results. The main value of the stochastic theory for a system of entangled solitons lies in the possibility of modeling the entangled states of real systems - photons. In the framework of this work, the optical 1D envelopes of solitons in a nematic liquid crystal are considered in approximation to the conditions of a real physical problem. Research implications. The theoretical and/or practical significance lies in the fundamental possibility of modeling real entangled systems based on the constructed stochastic model of entangled solitons and subsequent creation of special applications on its basis. In particular, there will be a prospect of applying quantum teleportation to the problem of propagation of quantum computing for use among the components of quantum computing networks.
Characterization of strip and pixel AC-LGAD devices with both laser TCT and probe station (IV/CV) will be shown on AC-LGADs irradiated with 1 MeV reactor neutrons at JSI/Ljubljana and with 400~MeV protons at FNAL ITA to fluences from 1e13~$n_{eq}/cm^2$ to a few times 1e15~$n_{eq}/cm^2$. This study was conducted within the scope of the ePIC detector time of flight (TOF) layer R\&D program at the EIC, which will feature AC-LGADs with strip and pixel geometry. Sensors in the TOF layer will receive up to 1e13~$n_{eq}/cm^2$ fluence over the lifetime of the experiment.
We examine the application of metamaterials for impact noise insulation in tiled floors. A ceramic metatile is developed which makes use of phononic metamaterials and optimized joint configurations. First, we optimize the geometrical and material parameters of the proposed metatile, which is composed of small ceramic tiles connected by silicon joints, in order to reduce longitudinal and flexural wave propagation on tiled floors. A bandgap is achieved that effectively mitigates the transmission of impact noise through periodic structural pathways. In both experimental and numerical tests, it is demonstrated that the integration of silicon joints inside the ceramic metatile improves the acoustic insulation performance, as measured by the reduction of impact noise levels across a wide range of low frequencies. The findings highlight the potential of metamaterials in architectural acoustics, offering innovative solutions for sound control in tiled environments.
The design and development of effective drug formulations is a critical process in pharmaceutical research, particularly for small molecule active pharmaceutical ingredients. This paper introduces a novel agentic preformulation pathway assistant (Appa), leveraging large language models coupled to experimental databases and a suite of machine learning models to streamline the preformulation process of drug candidates. Appa successfully integrates domain expertise from scientific publications, databases holding experimental results, and machine learning predictors to reason and propose optimal preformulation strategies based on the current evidence. This results in case-specific user guidance for the developability assessment of a new drug and directs towards the most promising experimental route, significantly reducing the time and resources required for the manual collection and analysis of existing evidence. The approach aims to accelerate the transition of promising compounds from discovery to preclinical and clinical testing.
A recently proposed scatter-window and deep learning-based attenuation compensation (AC) method for myocardial perfusion imaging (MPI) by single-photon emission computed tomography (SPECT), namely CTLESS, demonstrated promising performance on the clinical task of myocardial perfusion defect detection with retrospective data acquired on SPECT scanners from a single vendor. For clinical translation of CTLESS, it is important to assess the generalizability of CTLESS across different SPECT scanners. For this purpose, we conducted a virtual imaging trial, titled in silico imaging trial to assess generalizability (ISIT-GEN). ISIT-GEN assessed the generalizability of CTLESS on the cardiac perfusion defect detection task across SPECT scanners from three different vendors. The performance of CTLESS was compared with a standard-of-care CT-based AC (CTAC) method and a no-attenuation compensation (NAC) method using an anthropomorphic model observer. We observed that CTLESS had receiver operating characteristic (ROC) curves and area under the ROC curves similar to those of CTAC. Further, CTLESS was observed to significantly outperform the NAC method across three scanners. These results are suggestive of the inter-scanner generalizability of CTLESS and motivate further clinical evaluations. The study also highlights the value of using in silico imaging trials to assess the generalizability of deep learning-based AC methods feasibly and rigorously.
In this paper, the social impact theory introduced by Latan\'e is reconsidered. A fully differentiated society is considered; that is, initially every actor has their own opinion. The equivalent of Muller's ratchet guards that -- even for the non-deterministic case (with a positive social temperature) -- any opinion once removed from the opinion space does not appear again. With computer simulation, we construct the phase diagram for Latan\'e model based on the number of surviving opinions after various evolution times. The phase diagram is constructed on the two-dimensional plane of model control parameters responsible for the effective range of interaction among actors and the social temperature. Introducing the Muller's ratchet-like mechanism gives a non-zero chance for any opinion to be removed from the system. We believe that in such a case, for any positive temperature, ultimately a consensus is reached. However, even for a moderate system size, the time to reach consensus is very long. In contrast, for the deterministic case (without social temperature), the system may be frozen with clusters of actors having several different opinions, or even reach the cycle limit (with blinking structures).
We have developed a new True Triaxial Apparatus (TTA) for rock deformation consisting of six servo-controlled loading rams that transmit maximum stresses of 220 MPa in the two horizontal axes and 400 MPa in the vertical axis to 50 mm side cubic rock samples. The sample and loading platens are introduced in a steel vessel where rock specimens can be subjected to up to 60 MPa of confining pressure, and pore fluids line connected to two pump intensifiers allow for highly accurate permeability measurements along the three loading axes. We present a suite of Finite Element Method (FEM) models implemented to determine the conditions and loading configuration that minimise the loading boundary effects during true triaxial loading. These observations are generic and we expect they will contribute to the development of true triaxial loading systems generally. Finally, we validate our experimental configuration by presenting results on permeability measurements along the three axes on cubic samples of three types of well studied rocks: Darley Dale sandstone, Crab Orchard sandstone, and Etna basalt.
This work introduces CTorch, a PyTorch-compatible, GPU-accelerated, and auto-differentiable projector toolbox designed to handle various CT geometries with configurable projector algorithms. CTorch provides flexible scanner geometry definition, supporting 2D fan-beam, 3D circular cone-beam, and 3D non-circular cone-beam geometries. Each geometry allows view-specific definitions to accommodate variations during scanning. Both flat- and curved-detector models may be specified to accommodate various clinical devices. CTorch implements four projector algorithms: voxel-driven, ray-driven, distance-driven (DD), and separable footprint (SF), allowing users to balance accuracy and computational efficiency based on their needs. All the projectors are primarily built using CUDA C for GPU acceleration, then compiled as Python-callable functions, and wrapped as PyTorch network module. This design allows direct use of PyTorch tensors, enabling seamless integration into PyTorch's auto-differentiation framework. These features make CTorch an flexible and efficient tool for CT imaging research, with potential applications in accurate CT simulations, efficient iterative reconstruction, and advanced deep-learning-based CT reconstruction.
The production and characteristics of protonated small water clusters (PSWCs) were reported in this work, where in electrospray ionization (ESI) of pure water, the species obtained were singly charged molecular ions consisting of 2, 3, 4 or 5 water molecules attached to a hydrogen ion, [(H2O)n+H]+, where n = 2, 3, 4 or 5. We proposed a new type of PSWCs structure: 2, 3, 4, 5 water molecules wrapped around a hydrogen ion which is located at the electrical and geometric center, forming a very stable molecular structure. Furthermore, biological tests of the PSWCs on mitochondrial function of intestinal epithelial cells and liver cells in mice showed the better therapeutic effect on inflammatory bowel diseases compared to that of the biologic agent Infliximab.
Integrated coherent sources of ultra-violet (UV) light are essential for a wide range of applications, from ion-based quantum computing and optical clocks to gas sensing and microscopy. Conventional approaches that rely on UV gain materials face limitations in terms of wavelength versatility; in response frequency upconversion approaches that leverage various optical nonlinearities have received considerable attention. Among these, the integrated thin-film lithium niobate (TFLN) photonic platform shows particular promise owing to lithium niobate's transparency into the UV range, its strong second order nonlinearity, and high optical confinement. However, to date, the high propagation losses and lack of reliable techniques for consistent poling of cm-long waveguides with small poling periods have severely limited the utility of this platform. Here we present a sidewall poled lithium niobate (SPLN) waveguide approach that overcomes these obstacles and results in a more than two orders of magnitude increase in generated UV power compared to the state-of-the-art. Our UV SPLN waveguides feature record-low propagation losses of 2.3 dB/cm, complete domain inversion of the waveguide cross-section, and an optimum 50% duty cycle, resulting in a record-high normalized conversion efficiency of 5050 %W$^{-1}$cm$^{-2}$, and 4.2 mW of generated on-chip power at 390 nm wavelength. This advancement makes the TFLN photonic platform a viable option for high-quality on-chip UV generation, benefiting emerging applications.
Kinetic simulations of relativistic gases and plasmas are critical for understanding diverse astrophysical and terrestrial systems, but the accurate construction of the relativistic Maxwellian, the Maxwell-J\"uttner (MJ) distribution, on a discrete simulation grid is challenging. Difficulties arise from the finite velocity bounds of the domain, which may not capture the entire distribution function, as well as errors introduced by projecting the function onto a discrete grid. Here we present a novel scheme for iteratively correcting the moments of the projected distribution applicable to all grid-based discretizations of the relativistic kinetic equation. In addition, we describe how to compute the needed nonlinear quantities, such as Lorentz boost factors, in a discontinuous Galerkin (DG) scheme through a combination of numerical quadrature and weak operations. The resulting method accurately captures the distribution function and ensures that the moments match the desired values to machine precision.
A setup for extreme-ultraviolet time-resolved photoelectron spectroscopy (XUV-TRPES) of liquids is described based on a gas-dynamic flat jet formed by a microfluidic chip device. In comparison to a cylindrical jet that has a typical diameter of 10-30 micrometers, the larger surface area of the flat jet with a width of ca. 300 micrometers allows for full overlap of the target with the pump and probe light beams. This results in an enhancement of photoelectrons emitted from the liquid, while simultaneously allowing smaller sample consumption compared with other flat jet techniques utilizing liquid collisions or converging slits. Femtosecond pulses of XUV light at a photon energy of 21.7 eV are prepared by high harmonic generation and a multilayer mirror that selects a single harmonic; the He gas used to form the gas-dynamic flat jet is transparent at this energy. Compared to a cylindrical jet, the photoelectron signal from the liquid is enhanced relative to that from the surrounding vapor jacket. Pump-probe spectra for aqueous thymine show notably higher signals for the flat vs cylindrical jet. Moreover, the time-dependent space-charge shift in UV pump/XUV probe experiments is smaller for the gas dynamic flat jet than for a cylindrical jet with the same flow rate, an effect that is accentuated at higher He backing pressures that yield a thinner jet. This reflects reduced multiphoton ionization of the solute by the UV pump pulse, the primary cause of the space charge shift, as the jet becomes thinner and reaches the thickness of a few tens of nm.
Electromagnetic design relies on an accurate understanding of light-matter interactions, yet often overlooks electronic length scales. Under extreme confinement, this omission can lead to nonclassical effects, such as nonlocal response. Here, we use mid-infrared phonon-polaritons in hexagonal boron nitride (hBN) screened by monocrystalline gold flakes to push the limits of nanolight confinement unobstructed by nonlocal phenomena, even when the polariton phase velocity approaches the Fermi velocities of electrons in gold. We employ near-field imaging to probe polaritons in nanometre-thin crystals of hBN on gold and extract their complex propagation constant, observing effective indices exceeding 90. We further show the importance of sample characterisation by revealing a thin low-index interfacial layer naturally forming on monocrystalline gold. Our experiments address a fundamental limitation posed by nonlocal effects in van der Waals heterostructures and outline a pathway to bypass their impact in high-confinement regimes.
A high-granularity crystal calorimeter (HGCCAL) has been proposed for the future Circular Electron Positron Collider (CEPC). This study investigates the time resolution of various crystal - Silicon Photomultiplier (SiPM) detection units for HGCCAL, focusing on Bismuth Germanate (BGO), Lead Tungstate (PWO), and Bismuth Silicon Oxide (BSO) crystals. Beam tests were conducted using 10 GeV pions at CERN and 5 GeV electrons at DESY, enabling systematic comparisons of timing performance under both minimum ionizing particle (MIP) signals and electromagnetic (EM) showers. Three timing methods - constant fraction timing (CFT) with sampled points, linear fitting, and exponential fitting - were evaluated, with an exponential fit combined with a 10% constant fraction providing the best time resolution. Measurements of crystal units with different dimensions revealed that both scintillation light yield and signal rise time influence timing performance. Among similarly sized crystals, PWO exhibited the best time resolution due to its fast signal rise time, while BGO and BSO demonstrated comparable timing performance. For long BGO bars (40 cm and 60 cm), the time resolution remained uniform along their length, achieving approximately 0.75 ns and 0.95 ns for MIP signals. Under intense EM showers, both bars reached a timing resolution of approximately 200 ps at high amplitudes. And the presence of upstream pre-shower layers can introduce additional timing fluctuations at similar amplitudes.
Neutral-atom arrays are a leading platform for quantum technologies, offering a promising route toward large-scale, fault-tolerant quantum computing. We propose a novel quantum processing architecture based on dual-type, dual-element atom arrays, where individually trapped atoms serve as data qubits, and small atomic ensembles enable ancillary operations. By leveraging the selective initialization, coherent control, and collective optical response of atomic ensembles, we demonstrate ensemble-assisted quantum operations that enable reconfigurable, high-speed control of individual data qubits and rapid mid-circuit readout, including both projective single-qubit and joint multi-qubit measurements. The hybrid approach of this architecture combines the long coherence times of single-atom qubits with the enhanced controllability of atomic ensembles, achieving high-fidelity state manipulation and detection with minimal crosstalk. Numerical simulations indicate that our scheme supports individually addressable single- and multi-qubit operations with fidelities of 99.5% and 99.9%, respectively, as well as fast single- and multi-qubit state readout with fidelities exceeding 99% within tens of microseconds. These capabilities open new pathways toward scalable, fault-tolerant quantum computation, enabling repetitive error syndrome detection and efficient generation of long-range entangled many-body states, thereby expanding the quantum information toolbox beyond existing platforms.
In this study, a method for readily and inexpensively generating real-time reconfigurable intense midair ultrasound field is proposed. Recent investigations and applications of midair convergent high-power ultrasound have been increasingly growing. For generating such ultrasound fields, specifically designed ultrasound sources or phased arrays of ultrasound transducers are conventionally used. The former can be more readily fabricated but cannot drastically reconfigure the generated ultrasound field, and the latter can create electronically controllable ultrasound fields but is much more difficult to implement and expensive. The proposed method utilizes a planar ultrasound source with a fixed surface vibration pattern and a newly designed amplitude mask inspired by the Fresnel-zone-plate (FZP). The mask is designed so that when it is placed on a specific position on the source, the partially covered source emission results in forming pre-determined ultrasound fields with corresponding specific spatial pattern. With these new masks, the generated fields can be switched among several presets by changing the mask position on the source. The proposed technique only requires slight mechanical translation of the mask over the source to instantaneously reconfigure the resulting midair ultrasound field. The proposed method enables one to create a reconfigurable ultrasound field with a large source aperture in a practically feasible setup, which will potentially broaden the workspace of current midair-ultrasound applications to the whole-room scale.
Here we perform the first analysis of high-fidelity simulations of the propagation of lean hydrogen flames through porous media, taking cylindrical arrays a representative example geometry. In this fundamental study we discuss the impact of confinement on both thermodiffusive and thermoacoustic instabilities. Flame propagation in these complex geometries is cannot be performed by leading mesh-based codes, and is instead simulated using a high-order meshfree method, LABFM. Pore scale propagation is shown to be dependent on throat width between cylinders, and this is then related to large-scale flame dynamics, allowing us to give a heuristic explanation for the increased growth rate of the thermodiffusive instability in more confined geometries. Thermoacoustic instabilities are also observed for sufficiently confined geometries. Understanding these instability mechanisms is crucial for improving the design of future combustors, both in terms of controlling flame dynamics and increasing the durability of combustors.
We introduce a new open-source Python x-ray tracing code for modelling Bragg diffracting mosaic crystal spectrometers: High Energy Applications Ray Tracer (HEART). HEART's high modularity enables customizable workflows as well as efficient development of novel features. Utilizing Numba's just-in-time (JIT) compiler and the message-passing interface (MPI) allows running HEART in parallel leading to excellent performance. HEART is intended to be used for modelling x-ray spectra as they would be seen in experiments that measure x-ray spectroscopy with a mosaic crystal spectrometer. This enables the user to, for example, make predictions about what will be seen on a detector in experiment, perform optimizations on the design of the spectrometer setup, or to study the effect of the spectrometer on measured spectra. However, the code certainly has further uses beyond these example use cases. Here, we discuss the physical model used in the code, and explore a number of different mosaic distribution functions, intrinsic rocking curves, and sampling approaches which are available to the user. Finally, we demonstrate its strong predictive capability in comparison to spectroscopic data collected at the European XFEL in Germany.
Predicting microporosity and permeability in clastic reservoirs is a challenge in reservoir quality assessment, especially in formations where direct measurements are difficult or expensive. These reservoir properties are fundamental in determining a reservoir's capacity for fluid storage and transmission, yet conventional methods for evaluating them, such as Mercury Injection Capillary Pressure (MICP) and Scanning Electron Microscopy (SEM), are resource-intensive. The aim of this study is to develop a cost-effective machine learning model to predict complex reservoir properties using readily available field data and basic laboratory analyses. A Random Forest classifier was employed, utilizing key geological parameters such as porosity, grain size distribution, and spectral gamma-ray (SGR) measurements. An uncertainty analysis was applied to account for natural variability, expanding the dataset, and enhancing the model's robustness. The model achieved a high level of accuracy in predicting microporosity (93%) and permeability levels (88%). By using easily obtainable data, this model reduces the reliance on expensive laboratory methods, making it a valuable tool for early-stage exploration, especially in remote or offshore environments. The integration of machine learning with uncertainty analysis provides a reliable and cost-effective approach for evaluating key reservoir properties in siliciclastic formations. This model offers a practical solution to improve reservoir quality assessments, enabling more informed decision-making and optimizing exploration efforts.
In recent years, networks with higher-order interactions have emerged as a powerful tool to model complex systems. Comparing these higher-order systems remains however a challenge. Traditional similarity measures designed for pairwise networks fail indeed to capture salient features of hypergraphs, hence potentially neglecting important information. To address this issue, here we introduce two novel measures, Hyper NetSimile and Hyperedge Portrait Divergence, specifically designed for comparing hypergraphs. These measures take explicitly into account the properties of multi-node interactions, using complementary approaches. They are defined for any arbitrary pair of hypergraphs, of potentially different sizes, thus being widely applicable. We illustrate the effectiveness of these metrics through clustering experiments on synthetic and empirical higher-order networks, showing their ability to correctly group hypergraphs generated by different models and to distinguish real-world systems coming from different contexts. Our results highlight the advantages of using higher-order dissimilarity measures over traditional pairwise representations in capturing the full structural complexity of the systems considered.
Electron acoustic waves (EAWs) are nonlinear plasma modes characterized by electron trapping, which suppresses the usual Landau damping. Despite being predicted in the 1990s, their excitation and decay mechanisms remain a subject of active research. This study investigates the nonlinear dynamics of EAWs, focusing on their excitation, decay instability, and the role of vortex merging in phase space. Using Eulerian Vlasov-Poisson simulations, we reproduce the excitation of stable EAWs via an external resonant driving force and explore their decay under the effect of a low-amplitude perturbation. The study identifies a distinct 2 to 1 decay process, where an EAW with a shorter wavelength merges into a longer-wavelength mode, driven by vortex dynamics in phase space. We find that the instability is triggered by a small fraction of particles capable of transitioning between potential wells, facilitating energy exchange between two adjacent phase space holes and vortex merging. Our simulations highlight the chaotic nature of particle trajectories in the vicinity of the separatrix between trapped and free phase space regions, which significantly contributes to the instability growth. Additionally, we analyze the influence of the perturbation amplitude on the growth rate of the instability, shedding light on the critical role of phase-space dynamics in the decay process. These findings offer a deeper understanding of the nonlinear behavior of plasma waves and suggest future directions for studying plasma wave stability in more complex systems, as the decay mechanism discussed here is likely to be universal in plasmas with closed separatrices in phase space, underscoring its significance in nonlinear plasma dynamics.
In this work, the Theory of Porous Media (TPM) is employed to model percutaneous vertebroplasty, a medical procedure in which acrylic cement is injected into cancellous vertebral bone. Previously, isothermal macroscale models have been derived to describe this material injection and the mechanical interactions which arise. However, the temperature of the injected cement is typically below the human body temperature, necessitating the extension of these models to the non-isothermal case. Following the modelling principles of the TPM and considering local thermal non-equilibrium conditions, our model introduces three energy balances as well as additional constitutive relations. If restricted to local thermal equilibrium conditions, our model equations are in agreement with other examples of TPM-based models. We observe that our model elicits physically reasonable behaviour in numerical simulations which employ parameter values and initial and boundary conditions relevant for our application. Noting that we neglect capillary effects, we claim our model to be thermodynamically consistent despite the employment of simplifying assumptions during its derivation, such as the Coleman and Noll procedure.
Chiral systems exhibit unique properties traditionally linked to their asymmetric spatial arrangement. Recently, multiple laser pulses were shown to induce purely electronic chiral states without altering the nuclear configuration. Here we propose and numerically demonstrate a simpler realization of light-induced electronic chirality that is long-lived and occurs much before the onset of nuclear motion. Specifically, a single monochromatic circularly-polarized laser pulse can induce electronic chiral currents in an oriented achiral molecule. We analyze this effect with state-of-the-art ab-initio theory and connect the induced electronic chiral currents directly to induced magnetic dipole moments, which are detectable using attosecond transient absorption electronic circular dichroism spectroscopy. Our findings show that the chiral electronic wavepacket rapidly oscillates in handedness at frequencies corresponding to higher-order harmonics of the pump laser's carrier frequency, and the currents survive well after the laser pulse has turned off. Therefore, we propose a light-induced chiral molecular-current analogue to high harmonic generation, paving the way to attosecond transient chirality controlled by a single laser pulse. Such ultrafast chiral transients could enable emerging technologies such as enhanced spintronics, coherent control of chemical reactions, and more.
This study extends the differentiable vortex particle method (DVPM) beyond idealized flow scenarios to encompass more realistic, non-ideal conditions, including viscous flow and flow subjected to non-conservative body forces. We establish the Lamb-Oseen vortex as a benchmark case, representing a fundamental viscous single vortex flow in fluid mechanics. This selection offers significant analytical advantages, as the Lamb-Oseen vortex possesses an exact analytical solution derived from the Navier-Stokes (NS) equations, thereby providing definitive ground truth data for training and validation purposes. Through rigorous evaluation across a spectrum of Reynolds numbers, we demonstrate that DVPM achieves superior accuracy in modeling the Lamb-Oseen vortex compared to conventional convolutional neural networks (CNNs) and physics-informed neural networks (PINNs). Our results substantiate DVPM's robust capabilities in modeling non-ideal single vortex flows, establishing its distinct advantages over contemporary deep learning methodologies in fluid dynamics applications. The dataset and source code are publicly available on GitHub at the following link: https://github.com/jh36714753/Learning_Non-Ideal_Single_Vortex_Flows.
Living cells exhibit non-equilibrium dynamics emergent from the intricate interplay between molecular motor activity and its viscoelastic cytoskeletal matrix. The deviation from thermal equilibrium can be quantified through frequency-dependent effective temperature or time-reversal symmetry breaking quantified e.g. through the Kullback-Leibler divergence. Here, we investigate the fluctuations of an AFM tip embedded within the active cortex of mitotic human cells with and without perturbations that reduce cortex activity through inhibition of material turnover or motor proteins. While inhibition of motor activity significantly reduces both effective temperature and time irreversibility, inhibited material turnover leaves the effective temperature largely unchanged but lowers the time irreversibility and entropy production rate. Our experimental findings in combination with a minimal model highlight that time irreversibility, effective temperature and entropy production rate can follow opposite trends in active living systems, challenging in particular the validity of effective temperature as a proxy for the distance from thermal equilibrium. Furthermore, we propose that the strength of thermal noise and the occurrence of time-asymmetric deflection spikes in the dynamics of regulated observables are inherently coupled in living systems, revealing a previously unrecognized link between entropy production and time irreversibility.
A pedestrian model's computation speed impacts the model applicability. However, little attention has been given to this model property in the field of pedestrian dynamics modelling. As such, no framework exists to guide the systematic analysis of a pedestrian models' computational speed. This contribution presents the APS framework (Assess Pedestrian model Speed framework), a framework to determine the speed of (pedestrian) dynamics models. APS features three methods to assess the computational speed of an algorithm, each tailored specifically to the use case of pedestrian models. It also provides guidance in choosing the proper method or methods depending on the goal and requirements of the analysis. APS also includes a new procedure to produce test cases. By using multiple test cases, the framework ensures that the dependency of a model's computational speed on the simulated scenario is assessed systematically.
Efficient peptide adsorption on metasurfaces is essential for advanced biosensing applications. In this study, we demonstrate how ellipsometric measurements coupled with numerical simulations allow for real-time tracking of temporin-SHa peptide adsorption on gold metasurfaces. By characterizing spectral shifts at 660 nm, 920 nm, and 1000 nm, we reveal a rapid saturation of surface coverage after 3.5 hours, with a significant preferential adsorption at the resonator ends. Our approach provides a novel methodology for monitoring peptide binding, which could be applied to a wide range of biosensor designs.
Effective problem-solving in physics extends beyond the mere application of mathematical formulas; it necessitates an understanding of how mathematical concepts connect to and reflect the physical world. A strong epistemological framework based on problem framing (PF) is essential for students, as it enables them to justify their mathematical decisions and recognize the relationship between abstract mathematics and real-world physical phenomena. This becomes increasingly important in the age of artificial intelligence (AI), where the use of Large Language Models (LLMs) in education is growing rapidly. This paper explores the impact of AI, specifically LLMs like ChatGPT, on upper-level students' PF in physics education. Building on existing models, in this exploratory theoretical paper, we propose a novel three-dimensional framework grounded in Situated Cognition Theory and Greeno's extended semantic model, aiming to elucidate how AI could influence students' epistemological framing during Cooperative Problem Solving activities (CPS). We advocate for instructors to encourage AI-assisted CPS to foster critical thinking and enhance student engagement with real-world scenarios. Preliminary results suggest that ChatGPT can aid in developing symbolic and visual languages within problem framing, though further research is needed to confirm these findings and investigate the potential of AI-driven intelligent tutoring systems for personalized learning.
We present a full-duplex 10Gb/s FSO bridge between two single-mode ports, utilizing centralized beamforming and simultaneous channel sounding. We further mitigate turbulence-induced fading through diversity reception enabled by wavelength-set coding.
Terrestrial free-space optical (FSO) links are an ideal candidate to extend the bandwidth continuum offered by fiber networks, yet at the expense of unfavorable cost credentials due to highly complex opto-mechanical setups. As a response to this challenge, we present a simple fiber-based focal plane array (FPA) architecture which contributes beamforming functionality to an FSO link that bridges the gap between two single-mode fiber ports. Through use of space-switched and wavelength-routed beamforming networks, which together with a photonic lantern provide a compact arrangement of up to 61 fine-pitched optical antenna elements on a fiber tip, we experimentally demonstrate that our FPA can assist the channel optimization of an FSO link after rough initial beam pointing. We show that favorable coupling conditions can be accomplished between two standard single-mode fibers, which enables us to successfully retain the fiber continuum by achieving error-free 10 Gb/s/{\lambda} data transmission in a space-switched out-door fiber-wireless-fiber scenario.
As the global climate changes, urban heat island (UHI) is a critical factor in ever expanding urban landscape, studying and mitigating the UHI is important for remediating climate change and providing for the human and ecosystem health within the urban area. This study has aimed to study the UHI in Lafia, a tropical city in Nigeria and its other impacted factors such as the land surface temperature (LST) and normalized difference vegetation index (NDVI), with the aim of mitigating the UHI effect. Landsat 4, 5, 7 and 8 together with Sentinel data has been used for this study, through the public archive of the Google Earth Engine data catalog, used also is the ERA5 data from the same data catalog. The result showed that the expanding city of Lafia is experiencing significant UHI with increase in temperatures in the city and adjoining areas, it was found that the vegetation cover in Lafia city is rapidly disappearing as a result of urbanization leading to more UHI and greater discomfort to the inhabitant of the city. Several remediation steps were suggested to mitigate the UHI effect in Lafia.
Electromagnetic calorimeters used in high-energy physics and astrophysics rely heavily on high-Z inorganic scintillators, such as lead tungstate (PbWO4 or PWO). The crystalline structure and lattice orientation of inorganic scintillators are frequently underestimated in detector design, even though it is known that the crystalline lattice strongly modifies the features of the electromagnetic processes inside the crystal. A novel method has been developed for precisely bonding PWO crystals with aligned atomic planes within 100 {\mu}rad, exploiting X-ray diffraction (XRD) to accurately measure miscut angles. This method demonstrates the possibility to align a layer of crystals along the same crystallographic direction, opening a new technological path towards the development of next-generation electromagnetic calorimeters.
Qualifying new detectors in test beam environments presents a challenging setting that requires stable operation of diverse devices, often employing multiple data acquisition systems. Changes to these setups are frequent, such as using different reference detectors depending on the facility. Managing this complexity necessitates a system capable of controlling the data taking, monitoring the experimental setup, facilitating seamless configuration, and easy integration of new devices. One aspect of such systems is network configuration. Many systems require fixed IP addresses for all machines participating in the data acquisition, which adds complexity for users. In this paper, a network protocol for network discovery tailored towards network-distributed control and data acquisition systems is described.
Quasicrystals are unique systems that, unlike periodic structures, lack translational symmetry but exhibit long-range order dramatically enriching the system properties. While evolution of light in the bulk of photonic quasicrystals is well studied, experimental evidences of light localization near the edge of truncated photonic quasicrystal structures are practically absent. In this Letter, we observe both linear and nonlinear localization of light at the edges of radially cropped quasicrystal waveguide arrays, forming an aperiodic Penrose tiling. Our theoretical analysis reveals that for certain truncation radii, the system exhibits linear eigenstates localized at the edge of the truncated array, whereas for other radii, this localization does not occur, highlighting the significant influence of truncation on edge light localization. Using single-waveguide excitations, we experimentally confirm the presence of localized states in Penrose arrays inscribed by a femtosecond laser and investigate the effects of nonlinearity on these states. Our theoretical findings identify a family of edge solitons, and experimentally, we observe a transition from linear localized states to edge solitons as the power of the input pulse increases. Our results represent the first experimental demonstration of localization phenomena induced by the selective truncation of quasiperiodic photonic systems.
Polaritonic chemistry offers the possibility of modifying molecular properties and even influencing chemical reactivity through strong coupling between vibrational transitions and confined light modes in optical cavities. Despite considerable theoretical progress and due to the complexity of the coupled light-matter system, the fundamental mechanism how and if collective strong coupling can induce local changes of individual molecules is still unclear. We derive an analytical formulation of static polarizabilities within linear response theory for molecules under strong coupling using the cavity Born-Oppenheimer Hartree-Fock ansatz. This ab-initio method consistently describes vibrational strong coupling and electron-photon interactions even for ensembles of molecules. For different types of molecular ensemble, we observed local changes in the polarizabilities and dipole moments that are induced by collective strong coupling. Furthermore, we used the polarizabilities to calculate vibro-polaritonic Raman spectra in the harmonic approximation. This allows us to comprehensively compare the effect of vibrational strong coupling on IR and Raman spectra on an equal footing.
Van der Waals (vdW) materials have garnered growing interest for use as nanophotonic building blocks that offer precise control over light-matter interaction at the nanoscale, such as optical metasurfaces hosting sharp quasi-bound states in the continuum resonances. However, traditional fabrication strategies often rely on lift-off processes, which inherently introduce imperfections in resonator shape and size distribution, ultimately limiting the resonance performance. Here, an optimized fabrication approach for vdW-metasurfaces is presented that implements inverse patterning of the etching mask, resulting in increased resonator quality solely limited by the resolution of the electron beam lithography resist and etching. Applying this inverse fabrication technique on hexagonal boron nitride (hBN), quality (Q) factors exceeding $10^3$ in the visible spectral range were demonstrated, significantly surpassing previous results shown by lift-off fabricated structures. Additionally, the platforms potential as a biosensor was displayed, achieving competitive sensitivity and figure of merit of 220 in a refractive index sensing experiment. The inverse technique was applied to create chiral metasurfaces from hBN, using a two-height resonator geometry to achieve up to 50 % transmittance selectivity. This inverse lithography technique paves the way towards high-performances vdW-devices with high-Q resonances, establishing hBN as a cornerstone for next-generation nanophotonic and optoelectronic devices.
The Blanco transform fault system (BTFS) is highly segmented and represents an evolving transform plate boundary in the Northeast Pacific Ocean. Its seismic behavior was captured with a dense network of 54 ocean-bottom-seismometers operated for one year. We created a high-resolution earthquake catalog based on different machine learning onset pickers, resulting in a high-resolution seismicity catalog with 12.708 events outlining the current deformation and stress release along a major transform fault. Seismicity reveals lateral changes of seismic behavior, indicating seismic and aseismic fault patches or segments, complex along-strike and off-axis deformation, step-overs, and internal faulting within pull-apart basins. Seismicity along simple linear fault strands is localized within 2 km of the seafloor expression of the fault. Repeaters indicate an average of 21 cm slip, exceeding the geological slip rate by ~4 times. Based on the repeater behavior, we suggest that the (overall aseismic) slip is spatially very heterogeneous, consisting of many small seismic patches, each one releasing its seismic slip every 4 years. Along the BTFS, the coupling of the fault is variable and varies between fully locked and fully creeping. Local earthquake tomography shows elevated vp/vs values exceeding 2, suggesting significant serpentinization from seawater entering the transform faults, the oceanic crust and mantle. The study shows how to use modern machine learning pickers on OBS data to provide essential insights into the physics of faulting along major plate boundary faults in time and space, including the partitioning of slip seismic and aseismic faulting with high resolution.
An upgraded high-energy nanosecond pulsed laser system tailored for optical particle diagnostics and manipulation capable of pulse energies beyond Joule-level is presented. In addition to the notable output energy increase, the laser system maintains its capability to generate laser pulses with customizable temporal profiles and variable durations ($1$ ns to $1$ $\mu$s) along with a chirping range of several GHz over the pulse duration. The expanded output energy range is anticipated to greatly broaden the laser system's application potential, both for thermodynamic diagnostics via coherent Rayleigh-Brillouin scattering, by substantially lowering the particle density detection thresholds, as well as for particle manipulation, by facilitating more efficient optical trapping potentials for particle acceleration and deceleration.
The gyrokinetic particle-in-cell code PICLS is a full-f finite element tool to simulate turbulence in the tokamak scrape-off layer. During the previous year, the capability of PICLS was extended to encompass electromagnetic effects. Successful tests using the method of manufactured solutions were conducted on the freshly added Amp\`ere's-law-solver, and shear Alfv\'en waves were simulated to verify the new electromagnetic time step. However, as a code based on the $p_{||}$-formulation of the gyrokinetic equations, PICLS is affected by the Amp\`ere-cancellation problem. In order to bring higher-beta simulations within reach of our computational capacity, we implemented the mixed-variable formulation with pullback-scheme in a similar fashion to, e.g., EUTERPE, ORB5, or XGC. Here, we present the successful verification of the different electromagnetic formulations of PICLS by simulating shear-Alfv\'en waves in a test setup designed to minimize kinetic effects.
The tokamak is a world-leading concept for producing sustainable energy via magnetically-confined nuclear fusion. Identifying where to position the magnets within a tokamak, specifically the poloidal field (PF) coils, is a design problem which requires balancing a number of competing economic, physical, and engineering objectives and constraints. In this paper, we show that multi-objective Bayesian optimisation (BO), an iterative optimisation technique utilising probabilistic machine learning models, can effectively explore this complex design space and return several optimal PF coil sets. These solutions span the Pareto front, a subset of the objective space that optimally satisfies the specified objective functions. We outline an easy-to-use BO framework and demonstrate that it outperforms alternative optimisation techniques while using significantly fewer computational resources. Our results show that BO is a promising technique for fusion design problems that rely on computationally demanding high-fidelity simulations.
We present an inverse method for transforming a given parallel light emittance to two light distributions at different parallel target planes using two freeform reflectors. The reflectors control both the spatial and directional target coordinates of light rays. To determine the shape and position of the reflectors, we derive generating functions and use Jacobian equations to find the optical mappings to the two targets. The model is solved numerically by a three-stage least-squares algorithm. A feasibility condition is derived, which ensures that the reflectors are not self-intersecting. Several examples validate this condition and demonstrate the algorithm's capability of realizing complex distributions.
Systems with non-Hermitian potential or Floquet modulation often result in phase transition related phenomena. In this paper, we study the dual phase transitions in a one-dimensional lattice by introducing a defect containing both Floquet modulation and PT-symmetric potential. In such a configuration, we demonstrate how the gain-loss from PT-symmetry and the control parameters in Floquet modulation adjust the wave dynamic behaviors. When these parameters change, the system will undergo dual phase transitions from an energy-delocalized phase to a localized phase where energy oscillates with time, and then to a PT-symmetry broken phase with energy boost. In particular, we find that the energy oscillations in the second phase is resulted from the beating of two energy oscillations: one is introduced by the PT-symmetric potential and the other is introduced by the Floquet modulation, rather than the field interference of the defect modes. Furthermore, we find that the first phase transition can be non-exist and the second phase transition is affected by the Floquet parameters. Our results reveal the underlying physics of dual phase transitions that occur in simple lattice systems with PT-symmetric Floquet defect, which extends the study of non-Hermitian Floquet systems.
The upgraded Inner Tracking System (ITS2) of the ALICE experiment at the CERN Large Hadron Collider is based on Monolithic Active Pixel Sensors (MAPS). With a sensitive area of about 10 $m^2$ and 12.5 billion pixels, ITS2 represents the largest pixel detector in high-energy physics. The detector consists of seven concentric layers equipped with ALPIDE pixel sensors manufactured in the TowerJazz 180 nm CMOS Imaging Sensor process. The high spatial resolution and low material budget, in combination with small radial distance of the innermost layer from the interaction point, make the detector well suited for secondary vertex reconstruction as well as for tracking at low transverse momentum. This paper will present the detector performance during the LHC Run 3 and give an overview on the calibration methods and running experience.
When faced with overwhelming evidence supporting the reality of time dilation, confirmed in particular by the Hafele-Keating experiment, some anti-relativists reluctantly concede that time dilation applies to light clocks. However, they argue that the Theory of Relativity remains flawed, claiming that time dilation applies to light clocks only, not to massive objects. They assert that atomic clocks, which operate based on microwave radiation, merely create the illusion that the Hafele-Keating experiment confirms the theory. To refute this misconception, we introduce a thought experiment inspired by Schrodinger's cat, in which the fate of Einstein's cat depends on a "Sync-or-Die clock", an imaginary device that tests the synchronization between a light clock and a mechanical clock, potentially triggering the release of poison. By analyzing this scenario from both the inertial frame where the device is at rest and another in which it moves at constant velocity, we demonstrate that time dilation must apply to the mechanical clock in exactly the same way as it does to the light clock, highlighting the universality of relativistic time dilation.
We demonstrate the emergence and control of Floquet states and topological bound states in the continuum (TBICs) in a two-dimensional colored quantum random walk (cQRW) on a square lattice. By introducing three internal degrees of freedom-termed "colors"-and leveraging SU(3) group representations, we realize dispersive TBICs and intrinsic Floquet dynamics without the need for external periodic driving. Through Chern number calculations, we identify three distinct topological bands, revealing color-induced band mixing as a key mechanism underlying the natural formation of Floquet states. The cQRW framework enables precise tuning of quasi-energy spectra, supporting the emergence of localized edge states in topological band gaps and dispersive TBICs embedded within the bulk of other bands. These TBICs exhibit tunable group velocity, controllable excitation across energy regimes, and robustness, providing theoretical validation for their existence in a first-order Floquet system. Our findings position cQRWs as a powerful platform for investigating and harnessing TBICs and Floquet states, with potential applications in quantum information and communication technologies.
The thermal fluctuation spectrum of the electric field arising due to particle noise in a quiescent Vlasov-Poisson plasma was derived in the 1960s. Here, we derive the universal fluctuation spectrum of the electric field, at Debye and sub-Debye scales, for a turbulent Vlasov-Poisson plasma. This spectrum arises from what is likely to be the final cascade - a universal regime to be encountered at the extreme small-scale end of any turbulent cascade in a nearly collisionless plasma. The cascaded invariant is $C_2$, the quadratic Casimir invariant of the particle distribution function. $C_2$ cascades to small scales in position and velocity space via linear and nonlinear phase mixing, in such a way that the time scales of the two processes are critically balanced at every scale. We construct a scaling theory of the fluctuation spectrum of $C_2$ and of the electric field in wavenumber space. The electric-field spectrum is sufficiently steep for the nonlinear mixing to be controlled by the largest-scale electric fields, and so the $C_2$ cascade resembles the Batchelor cascade of a passive scalar. Our theory is supported by simulations of a forced 1D-1V plasma. We predict that the cascade is terminated at the wavenumber where the turbulent electric-field spectrum gives way to the thermal noise spectrum. The time scale for this small-scale cutoff to be reached is the dynamical time of phase-space mixing times a logarithmic factor in the plasma parameter - this is the first concrete demonstration of this property of Vlasov-Poisson turbulence, akin to how fluid turbulence dissipates energy at a rate independent (or nearly independent) of molecular diffusion. In the presence of the sub-Debye phase-space cascade - a scenario that may be ubiquitous - standard collisional plasma theory ceases to be valid. This calls for the development of new collision operators suited to such turbulent environments.
The presence of quantum effects in photosynthetic excitation energy transfer has been intensely debated over the past decade. Nonlinear spectroscopy cannot unambiguously distinguish coherent electronic dynamics from underdamped vibrational motion, and rigorous numerical simulations of realistic microscopic models have been intractable. Experimental studies supported by approximate numerical treatments that severely coarse-grain the vibrational environment have claimed the absence of long-lived quantum effects. Here, we report the first non-perturbative, accurate microscopic model simulations of the Fenna-Matthews-Olson photosynthetic complex and demonstrate the presence of long-lived excitonic coherences at 77 K and room temperature, which persist on picosecond time scales, similar to those of excitation energy transfer. Furthermore, we show that full microscopic simulations of nonlinear optical spectra are essential for identifying experimental evidence of quantum effects in photosynthesis, as approximate theoretical methods can misinterpret experimental data and potentially overlook quantum phenomena.
The complex physics of inner shell ionization of target atoms by heavy ion impact has remained only partially solved for decades. Recently, agreement between theory and experiment has been achieved by considering inner shell ionization of target atoms due to projectile electron capture in addition to direct Coulomb ionization including multiple ionization effects. A thorough investigation exhibits such a picture only if the atomic parameters of the target atoms are correct. In fact, the theoretical approach is found to be right, but the problem arises with the faulty atomic parameters. Furthermore, we show that fluorescence yields play a major role among the atomic parameters. We explore such a powerful method that enables us to measure the correct and accurate fluorescence yields for almost every element in the periodic table. As per our present knowledge, this in turn not only solves the said complex issue fully but also makes the PIXE analysis more reliable and accurate using both light and heavy ions.
Extreme heat and hurricane-induced blackouts could occur simultaneously in the summer, posing great challenges to community health and well-being. Cooling centers serve as a key adaptation strategy to alleviate heat stress, especially among heat-vulnerable populations. This study leverages mobility data to examine how affected communities utilize cooling centers in response to hurricane-blackout-heat compound hazards. Additionally, it examines disparities in cooling center usage, focusing on individuals with access and functional needs (AFNs) who are usually overlooked in emergency management practices. These populations include but are limited to older adults, individuals with limited English proficiency, people with disabilities, those without vehicle access, and lower-income households. Using the empirical case of Hurricane Beryl (2024) in Harris County, Texas, we find no statistically significant difference in visiting formal (established by the government) and informal cooling centers (operated by volunteer organizations). Census block groups closer to the nearest cooling center and those with lower income are more likely to seek shelter from extreme heat at cooling centers in the aftermath of Hurricane Beryl. Lower-income block groups also tend to be situated closer to cooling centers, suggesting that Harris County may have strategically placed them in areas with greater social vulnerability. Furthermore, we investigate visiting hotels as an alternative but more expensive adaptation strategy during Hurricane Beryl. Between these two adaptation options, shorter distances to cooling centers, lower income, and elder age are statistically significantly associated with a higher probability of visiting cooling centers rather than hotels, while limited English proficiency significantly decreases such probability.
The usability of enzymatically induced calcium carbonate precipitation (EICP) as a method for altering porous-media properties, soil stabilization, or biocementation depends on our ability to predict the spatial distribution of the precipitated calcium carbonate in porous media. While current REV-scale models are able to reproduce the main features of laboratory experiments, they neglect effects like the formation of preferential flow paths and the appearance of multiple polymorphs of calcium carbonate with differing properties. We show that extending an existing EICP model by the conceptual assumption of a mobile precipitate, amorphous calcium carbonate (ACC), allows for the formation of preferential flow paths when the initial porosity is heterogeneous. We apply sensitivity analysis and Bayesian inference to gain an understanding of the influence of characteristic parameters of ACC that are uncertain or unknown and compare two variations of the model based on different formulations of the ACC detachment term to analyse the plausibility of our hypothesis. An arbitrary Polynomial Chaos (aPC) surrogate model is trained based on the full model and used to reduce the computational cost of this study.
Vacuum breakdown in accelerator structures is a critical challenge that occurs under high electric fields. In environments subjected to hydrogen ion irradiation or high beam losses, such as in Radio-Frequency Quadrupoles (RFQ), residual hydrocarbons from the vacuum may result in carbon contamination of the metal surfaces from charged particle induced cracking. Under these conditions, it has been assessed that surface carbon contamination leads to a decrement of the surface electric field holding properties. This study extends the latest research by exploring the efficacy of Oxygen Plasma Cleaning (OPC) on metal electrodes irradiated by low energy hydrogen ion beam with the purpose of reducing surface carbon contamination. OPC treatment has been employed on different metals, namely copper beryllium (CuBe2), oxygen-free copper (Cu-OFE), and stainless steel (SS316LN). Treated electrodes have been tested for electric field performance in a DC pulsed system and results compared with non-irradiated electrodes and irradiated ones without OPC treatment. The study indicates a significant reduction in carbon contamination by OPC, enough to allow irradiated materials to achieve performances comparable with the electric field strength of raw surfaces. Moreover, it has been observed that stainless steel samples had some alteration in the surface chemistry that enhanced the materials ability to sustain high electric fields while decreasing vacuum arcing events. Notably, OPC treated SS316LN electrodes surpassed the performance value of untreated ones, demonstrating the potential of plasma treatments in extending the operational performance of accelerator components.
During the 2024's quinquennial scientific roadmap of CNES, a specific group worked on setting recommendations to decrease the environmental footprint of space science activities. This correspondence to Nature Astronomy highlights the efforts of the french space research to move towards sustainability. It relies on two complementary methods: decarbonisation and frugality.
In generic classical and quantum many-body systems, where typically energy and particle number are the only conserved quantities, stationary states are described by thermal equilibrium. In contrast, integrable systems showcase an infinite hierarchy of conserved quantities that inhibits conventional thermalization, forcing relaxation to a Generalized Gibbs Ensemble (GGE), a concept first introduced in quantum many-body physics. In this study, we provide experimental evidence for the emergence of a GGE in a photonic system. By investigating partially coherent waves propagating in a normal dispersion optical fiber, governed by the one-dimensional defocusing nonlinear Schroedinger equation, we directly measure the density of states of the spectral parameter (rapidity) to confirm the time invariance of the full set of conserved charges. We also observe the relaxation of optical power statistics to the GGE's theoretical prediction, obtained using the experimentally measured density of states. These complementary measurements unambiguously establish the formation of a GGE in our photonic platform, highlighting its potential as a powerful tool for probing many-body integrability and bridging classical and quantum integrable systems.
We present the first study dedicated to measuring the timescales for black hole accretion and jet launch in a quasar at the edge of Reionization, PSO J352.4034-15.3373 at z = 5.832 $\pm$ 0.001. Previous work presented evidence of the strong radio synchrotron emission from the jet affecting the host galaxy dust-dominated continuum emission at $\nu_{\rm rest}=683$ GHz ($\nu_{\rm obs}=100$ GHz), implying a break in the synchrotron spectrum. In this work, we present quasi-simultaneous observations at 1.5\, GHz - 42\,GHz with the Karl G. Jansky Very Large Array (VLA), and derive a frequency break at $\nu^{\rm break}_{\rm rest} = 196.46$ GHz ($\nu^{\rm break}_{\rm obs} = 28.76$ GHz). Modeling these observations, we calculate the jet spectral aging from the cooling of electrons to be $t_{\mathrm{spec}}\sim 580$ yr. From this measurement, we approximate the dynamical age $t_{\mathrm{dyn}}$ to be $\sim2,000$ yr, implying a recent jet ejection. We compare the jet timescale to the quasar's lifetime ($t_{\mathrm{Q}}$) that indicates the duration of the latest black hole accretion event and is derived from the proximity zone size in the rest-UV/optical spectrum. However, a ghostly Damped Ly$\alpha$ (DLA) system affects this measurement yielding an upper limit of $t_{\mathrm{Q}} \lesssim 10^4$ yr, consistent with the jet lifetime and indicative of a young quasar. This suggests that the triggering of a UV-bright quasar phase may occur within comparable timescales as the launch of a relativistic radio jet. Therefore, we may be witnessing an early stage of black hole and jet interactions in a quasar during the first gigayear of the universe.
Antiferromagnets exhibiting the anomalous Hall effect represent a fascinating convergence of magnetism, topology, and electronic structure. Identifying antiferromagnets with large and tunable anomalous Hall effects is crucial for the development of spintronic applications. Here, we report a strain-tunable anomalous Hall plateau in CoNb$_3$S$_6$, which is a prime candidate for altermagnetism. The plateau emerges as a flat extended intermediate step of the anomalous Hall hysteresis loop with a controllable step height with temperature and strain. The remarkable tunability of the plateau position is in contrast with typical magnetic plateau associated with a field-induced metastable magnetic structure, but indicates the existence of a hidden phase transition that significantly alters the magnetic anisotropy energy without changing the magnetic order. The symmetry analysis of the strain tuning suggests that the hidden phase preserves the rotational symmetry of the ab-plane. Our results show the plateau reflects the phase coexistence during the hidden transition, and anomalous Hall resistivity of the plateau is thus non-volatile, enabling a novel four-state switching of the anomalous Hall effect.
Pyramid wavefront sensors (PWFSs) are the preferred choice for current and future extreme adaptive optics (XAO) systems. Almost all instruments use the PWFS in its modulated form to mitigate its limited linearity range. However, this modulation comes at the cost of a reduction in sensitivity, a blindness to petal-piston modes, and a limit to the sensor's ability to operate at high speeds. Therefore, there is strong interest to use the PWFS without modulation, which can be enabled with nonlinear reconstructors. Here, we present the first on-sky demonstration of XAO with an unmodulated PWFS using a nonlinear reconstructor based on convolutional neural networks. We discuss the real-time implementation on the Magellan Adaptive Optics eXtreme (MagAO-X) instrument using the optimized TensorRT framework and show that inference is fast enough to run the control loop at >2 kHz frequencies. Our on-sky results demonstrate a successful closed-loop operation using a model calibrated with internal source data that delivers stable and robust correction under varying conditions. Performance analysis reveals that our smart PWFS achieves nearly the same Strehl ratio as the highly optimized modulated PWFS under favorable conditions on bright stars. Notably, we observe an improvement in performance on a fainter star under the influence of strong winds. These findings confirm the feasibility of using the PWFS in its unmodulated form and highlight its potential for next-generation instruments. Future efforts will focus on achieving even higher control loop frequencies (>3 kHz), optimizing the calibration procedures, and testing its performance on fainter stars, where more gain is expected for the unmodulated PWFS compared to its modulated counterpart.
After successfully completing Phase I upgrades during LHC Long Shutdown 2, the ATLAS detector is back in operation with several upgrades implemented. The most important and challenging upgrade is in the Muon Spectrometer, where the two inner forward muon stations have been replaced with the New Small Wheels (NSW) system. One of the two detector technologies used in the NSW are the resistive Micromegas (MM). After massive construction, testing and installation work in ATLAS, the Micromegas are now fully operational in the experiment participating in the muon spectrometer tracking and trigger systems. A huge effort has gone into the operation of the new data acquisition system, as well as the implementation of a new processing chain within the muon software framework. Tracking is performed with full consideration of the absolute alignment of each individual detector module by the ATLAS Muon Spectrometer optical alignment system. All the deviations from the nominal geometry of all the constituent elements of each MM module are accounted for through the modelling of the real chamber geometry reconstructed from the information of the construction databases. After an overview of the strategies adopted for the simulations and reconstruction, the studies on the performance of the MM in LHC run-3 data taken from 2022 to 2024 will be reported.
We study laser-induced ultrafast magnetization reversal in ferromagnetic spin valve by comparing the effect of a direct laser excitation and an ultrashort hot-electron pulse. A wedged Cu layer is grown on top of the spin valve in order to tune the energy transmission to the magnetic stack, for both optical and hot-electron pulses. We demonstrate single-pulse magnetization reversal of the free layer by a hot-electron pulse. The influence of laser fluence, Cu thickness ($t_{\mathrm{Cu}}$), and pulse duration is investigated in detail. These results suggest that free layer heating plays a significant role in magnetization reversal. This work contributes to the understanding of ultrafast magnetization reversal due to nonlocal heat and spin transport occurring under strongly out-of-equilibrium conditions.
Accelerated materials discovery is an urgent demand to drive advancements in fields such as energy conversion, storage, and catalysis. Property-directed generative design has emerged as a transformative approach for rapidly discovering new functional inorganic materials with multiple desired properties within vast and complex search spaces. However, this approach faces two primary challenges: data scarcity for functional properties and the multi-objective optimization required to balance competing tasks. Here, we present a multi-property-directed generative framework designed to overcome these limitations and enhance site symmetry-compliant crystal generation beyond P1 (translational) symmetry. By incorporating Wyckoff-position-based data augmentation and transfer learning, our framework effectively handles sparse and small functional datasets, enabling the generation of new stable materials simultaneously conditioned on targeted space group, band gap, and formation energy. Using this approach, we identified previously unknown thermodynamically and lattice-dynamically stable semiconductors in tetragonal, trigonal, and cubic systems, with bandgaps ranging from 0.13 to 2.20 eV, as validated by density functional theory (DFT) calculations. Additionally, we assessed their thermoelectric descriptors using DFT, indicating their potential suitability for thermoelectric applications. We believe our integrated framework represents a significant step forward in generative design of inorganic materials.
Recent studies have shown some unusual nonlinear dispersion behaviors that are disconnected from the linear regime. However, existing analytical techniques, such as perturbation methods, fail to correctly capture these behaviors. Here we propose a general theoretical approach that converts the nonlinear wave equation to an equivalent linear eigenvalue problem, which directly gives the nonlinear dispersion relation and modal vectors. The theoretical approach is employed to 1D phononic chains and 2D hexagonal lattices with alternating softening and hardening nonlinearities, revealing amplitude-induced bandgap opening and closing phenomena. The theoretical results are validated via full-scale simulations with periodic boundary conditions, in which steady-state nonlinear plane wave responses are numerically obtained. Moreover, we leverage these nonlinear phenomena to achieve tunable frequency splitting and focusing effects. Thus, our work opens new paradigms for understanding nonlinear wave physics and for achieving novel wave control capabilities.
We develop a non-Lorentzian approach for quantum emitters (QE) resonantly coupled to localized surface plasmons (LSP) in metal-dielectric structures. Using the exact LSP Green function, we derive non-Lorentzian version of Maxwell-Bloch equations which describe LSP in terms of metal complex dielectric function rather than via Lorentzian resonances. For a single QE coupled to the LSP, we obtain an explicit expression for the system effective optical polarizability which, in the Lorentzian approximation, recovers the classical coupled oscillator (CO) model. We demonstrate that non-Lorentzian effects originating from the temporal dispersion of metal dielectric function affect dramatically the optical spectra as the system transitions to the strong coupling regime. Specifically, in contrast to Lorentzian models, the main spectral weight is shifted towards the lower energy polaritonic band, consistent with the experiment.
Photonically-interconnected matter qubit systems have wide-ranging applications across quantum science and technology, with entanglement between distant qubits serving as a universal resource. While state-of-the-art heralded entanglement generation performance thus far has been achieved in trapped atomic systems modelled as stationary emitters, the improvements to fidelities and generation rates demanded by large-scale applications require taking into account their motional degrees of freedom. Here, we derive the effects of atomic motion on spontaneous emission coupled into arbitrary optical modes, and study the implications for commonly-used atom-atom entanglement protocols. We arrive at a coherent physical picture in the form of "kick operators" associated with each instant in the photonic wavepackets, which also suggests a method to mitigate motional errors by disentangling qubit and motion post-herald. This proposed correction technique removes overheads associated with the thermal motion of atoms, and may greatly increase entanglement rates in long-distance quantum network links by allowing single-photon-based protocols to be used in the high-fidelity regime.
The covariant, spin-dependent response tensor for an electric dipole moment polarized electron gas (statistical distribution of electrons and positrons) is calculated using the formalism of quantum plasmadynamics. A simultaneous eigenfunction of both the Dirac Hamiltonian and the electric moment spin operator is constructed. Expressions for the electric moment states and the corresponding vertex functions are derived. It is shown that when the distribution of momenta is isotropic, the spin dependent response of an electric moment dependent quantum plasma is identically zero. The response is non-zero in the presence of a streaming motion perpendicular to the axis if the electron and positron distributions are different. The response has the same form as for a plasma with a nonzero, cross field current when $\langle p_{i} \rangle \neq 0$. This quantum relativistic correction is used to identify the dispersion equation for an electric moment spin polarised plasma with a streaming cold plasma background. In particular, the natural modes of an electric moment dependent quantum plasma exhibit elliptical polarisation. This is in contrast to a magnetic moment dependent electron gas, which is gyrotropic, or a helicity dependent electron gas which is optically active. The different responses, due to quantum plasmas being spin polarised by different relativistically acceptable spin operators, does not appear in other approaches to quantum plasma theory.
Three-dimensional special relativistic magnetohydrodynamic simulations are performed to investigate properties of the downstream turbulence generated by the interaction between a relativistic shock wave and multiple clumps. We analyze the properties of the downstream turbulence by performing the Helmholtz decomposition. It is shown that, in contrast to the non-relativistic shock case, the amplitude of compressive modes is comparable to that of solenoidal modes for the relativistic shock. In addition, many reflected shocks propagate in the downstream region. The strength of the compressive mode, the solenoidal mode, the reflected shock waves, and the amplified magnetic field depend on the amplitude of the upstream density fluctuations. Our simulation results suggest that the wide distribution of the ratio of the magnetic energy to the shock kinetic energy, $\epsilon_B$, in gamma-ray burst afterglows is due to the diversity of the gamma-ray burst environment. Furthermore, the inhomogeneity of density around high-energy astrophysical objects affects the spectrum of accelerated particles because the reflected shock and turbulence can inject and accelerate non-thermal particles in the shock downstream region. The probability distribution of the downstream quantities, power spectra of turbulence, and vortex generation are also analyzed and discussed in this work.
3D non-Cartesian trajectories offer several advantages over rectilinear trajectories for rapid volumetric imaging, including improved sampling efficiency and greater robustness to motion, flow, and aliasing artifacts. In this paper, we present a unified framework for designing three widely used non-Cartesian trajectories: 3D Radial, 3D Cones, and Stack-of-Spirals. Our approach is based on the idea that a non-Cartesian trajectory can be interpreted as a discretized version of an analytic coordinate defined by a set of template trajectories. Equivalently, the analytic coordinate is conceptualized as a non-Cartesian trajectory composed of an infinite number of copies of a set of template trajectories. The discretization is accomplished by constructing a continuous spiral path on a surface and sampling points along this path at unit intervals, leaving only the essential spokes/interleaves, thereby yielding the practical non-Cartesian trajectory from the analytic coordinate. One of the advantages of our approach is that the analytic density compensation factor can be readily derived using Jacobian determinants, which quantify changes in unit areas due to the transformation from the analytic coordinate to the Cartesian grid. Additionally, the proposed approach derives analytic formulae to compute the number of readouts based on prescribed parameters, allowing us to specify the trajectory's acceleration factor for a given total scan time. Furthermore, variable-density sampling can be easily incorporated, and spokes/interleaves are smoothly distributed in k-space along the derived spiral path, even for a small number of readouts. In a preliminary phantom study, the proposed method demonstrated improved sampling efficiency and image quality compared to the conventional approach.
Lattice thermal conductivity ($\kappa_L$) is crucial for efficient thermal management in electronics and energy conversion technologies. Traditional methods for predicting \k{appa}L are often computationally expensive, limiting their scalability for large-scale material screening. Empirical models, such as the Slack model, offer faster alternatives but require time-consuming calculations for key parameters such as sound velocity and the Gruneisen parameter. This work presents a high-throughput framework, physical-informed kappa (PINK), which combines the predictive power of crystal graph convolutional neural networks (CGCNNs) with the physical interpretability of the Slack model to predict \k{appa}L directly from crystallographic information files (CIFs). Unlike previous approaches, PINK enables rapid, batch predictions by extracting material properties such as bulk and shear modulus from CIFs using a well-trained CGCNN model. These properties are then used to compute the necessary parameters for $\kappa_L$ calculation through a simplified physical formula. PINK was applied to a dataset of 377,221 stable materials, enabling the efficient identification of promising candidates with ultralow $\kappa_L$ values, such as Ag$_3$Te$_4$W and Ag$_3$Te$_4$Ta. The platform, accessible via a user-friendly interface, offers an unprecedented combination of speed, accuracy, and scalability, significantly accelerating material discovery for thermal management and energy conversion applications.
The FCC program at CERN provides an attractive all-in-one solution to address many of the key questions in particle physics. While we fully support the efforts towards this ambitious path, we believe that it is important to prepare a mitigation strategy in case the program faces unexpected obstacles for geopolitical or other reasons. This approach could be based on two components: I) a circular electron-positron collider in the LHC tunnel that operates at the Z-pole energy of 45.6 GeV and II) a high-energy electron-positron linear collider which acts as a Higgs, top quark and W-boson factory, and that can further be extended to TeV energies. The former could reach a high luminosity that is not accessible at a linear collider, the latter could probe the high energy regime with higher sensitivity and discovery potential than LEP3. The program should be flanked by dedicated intensity frontier searches at lower energies. These accelerators can be used in a feasible, timely and cost-efficient way to search for new physics and make precise determination of the parameters of the Standard Model.
The bottom-up design of strongly interacting quantum materials with prescribed ground state properties is a highly nontrivial task, especially if only simple constituents with realistic two-body interactions are available on the microscopic level. Here we study two- and three-dimensional structures of two-level systems that interact via a simple blockade potential in the presence of a coherent coupling between the two states. For such strongly interacting quantum many-body systems, we introduce the concept of blockade graph automorphisms to construct symmetric blockade structures with strong quantum fluctuations that lead to equal-weight superpositions of tailored states. Drawing from these results, we design a quasi-two-dimensional periodic quantum system that - as we show rigorously - features a topological $\mathbb{Z}_2$ spin liquid as its ground state. Our construction is based on the implementation of a local symmetry on the microscopic level in a system with only two-body interactions.
By applying phase modulation across different frequencies, metasurfaces possess the ability to manipulate the temporal dimension of photons at the femtosecond scale. However, there remains a fundamental challenge to shape the single wavepacket at the nanosecond scale by using of metasurfaces. Here, we propose that the single photon temporal shape can be converted through the multi-photon wavepacket interference on a single metasurface. By selecting appropriate input single-photon temporal shapes and metasurfaces beam splitting ratio, controllable photon shape conversion can be achieved with high fidelity. For examples, photons with an exponentially decaying profile can be shaped into a Gaussian profile; by tuning the relative time delays of input photons, Gaussian-shaped photons can be transformed into exponentially decaying or rising profiles through the same metasurface. The proposed mechanism provides a compact way for solving the temporal shape mismatch issues in quantum networks, facilitating the realization of high-fidelity on-chip quantum information processing.
Advanced theoretical investigations are crucial for understanding the structural growth mechanisms, optoelectronic properties, and photocatalytic activity of photoelectrodes for efficient photoelectrochemical water splitting. In this work, we conducted first-principles calculations aimed at designing $\alpha$-Fe2O3 photoelectrodes incorporating mono-dopants such as boron (B), yttrium (Y), and niobium (Nb), as well as co-dopants (B, Y) and (B, Nb) to enhance the performance of photoelectrochemical cells. We assessed the thermodynamic phase stability by calculating formation enthalpy ($E_f$) and examining material properties, including microstrain ($\mu_\epsilon$) and crystallite size ($D$). The mono-dopants, Y and Nb, and the co-dopants, (B, Y) and (B, Nb), exhibited negative $E_f$ values under the substitutional doping method, confirming their thermodynamic phase stability and suggesting their practical viability for experimental implementation. Notably, the values of $\mu_\epsilon$ and $D$ fell within the ranges observed experimentally for $\alpha$-Fe2O3, indicating their effectiveness in growth mechanisms. To gain a comprehensive understanding of the optoelectronic properties of doped $\alpha$-Fe2O3, we calculated the electronic band structure, density of states, atom's ionic charge, and optical absorption coefficient. This analysis allowed us to examine the improvements in the electronic charge characteristics and photon-electron interactions. B-doped $\alpha$-Fe2O3 led to the formation of impurity bands, which were mitigated by utilizing co-dopants (B, Y) and (B, Nb). The metal dopants, Y and Nb, significantly increased the charge carrier density, while the co-dopants, (B, Y) and (B, Nb), substantially enhanced light absorption in the visible spectrum.
By analyzing the physics of multi-photon absorption in superconducting nanowire single-photon detectors (SNSPDs), we identify physical components of jitter. From this, we formulate a quantitative physical model of the multi-photon detector response which combines local detection mechanism and local fluctuations (hotspot formation and intrinsic jitter) with thermoelectric dynamics of resistive domains. Our model provides an excellent description of the arrival-time histogram of a commercial SNSPD across several orders of magnitude, both in arrival-time probability and across mean photon number. This is achieved with just three fitting parameters: the scaling of the mean arrival time of voltage response pulses, as well as the Gaussian and exponential jitter components. Our findings have important implications for photon-number-resolving detector design, as well as applications requiring low jitter such as light detection and ranging (LIDAR).
This paper presents progress towards the large-scale manufacturability of piezo- and ferroelectric Al$_{1-x}$Sc$_x$N thin films with very high Sc content. Al$_{0.6}$Sc$_{0.4}$N layers were deposited by reactive sputtering from a 300 mm diameter Al$_{0.6}$Sc$_{0.4}$N target on standard 200 mm Si wafers with Pt bottom- and Mo top-electrodes. The deposited films were analyzed in depth with X-Ray diffraction (XRD), Reciprocal Space Mapping (RSM), Scanning electron microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX) showing well oriented c-axis growth over the full wafer with slight variation in the film thickness and Sc content over the wafer radius. An overall low density of abnormally oriented grains (AOG) was found. Further wafer mapping for piezoelectric and dielectric properties showed a piezoelectric performance increase by 40 % in comparison to Al$_{0.7}$Sc$_{0.3}$N while only moderately increasing the permittivity and loss factor. Switching measurements revealed ferroelectric behavior of the film on all measured positions with an average remanent polarization of 88.36 uC/cm$^2$ and an average coercive field of 244 V/um. This successful demonstration opens new opportunities for MEMS applications with demands for high forces like microspeakers or quasi static micromirrors.
The primary focus of this thesis is the numerical investigation of chaos in Hamiltonian models describing charged particle orbits in plasma, star motions in barred galaxies, and orbits' diffusion in multidimensional maps. We systematically explore the interplay between magnetic and kinetic chaos in toroidal fusion plasmas, where non-axisymmetric perturbations disrupt smooth magnetic flux surfaces, generating complex particle trajectories. Using the Generalized Alignment Index (GALI) method, we efficiently quantify chaos, compare the behavior of magnetic field lines and particle orbits, visualize the radial distribution of chaotic regions, and offer GALI as a valuable tool for studying plasma physics dynamics. We also study the evolution of phase space structures in a 3D barred galactic potential, following successive 2D and 3D pitchfork and period-doubling bifurcations of periodic orbits. By employing the `color and rotation' technique to visualize the system's 4D Poincar\'e surface of sections, we reveal distinct structural patterns. We further investigate the long-term diffusion transport and chaos properties of single and coupled standard maps, focusing on parameters inducing anomalous diffusion through accelerator modes exhibiting ballistic transport. Using different ensembles of initial conditions in chaotic regions influenced by these modes, we examine asymptotic diffusion rates and time scales, identifying conditions suppressing anomalous transport and leading to long-term convergence to normal diffusion across coupled maps. Lastly, we perform the first comprehensive investigation into the GALI indices for various attractors in continuous and discrete-time dissipative systems, extending the method's application to non-Hamiltonian systems. A key aspect of our work involves analyzing and comparing GALIs' with Lyapunov Exponents for systems exhibiting hyperchaotic motion.
Here, we report on controlling strain in graphene by trapping molecules at the graphene-substrate interface, leveraging molecular dipole moments. Spectroscopic and transport measurements show that strain correlates with the dipole moments of trapped molecules, with a dipole range of 1.5 D to 4.9 D resulting in a 50-fold increase in strain and a substantial rise in the residual carrier density. This has been possible by charge transfer between graphene and trapped molecules, altering the C=C bond length, and causing biaxial strain. First-principles density functional theory calculations confirm a consistent dependence of bending height on molecular dipole moments.
The growing energy demands of HPC systems have made energy efficiency a critical concern for system developers and operators. However, HPC users are generally less aware of how these energy concerns influence the design, deployment, and operation of supercomputers even though they experience the consequences. This paper examines the implications of HPC's energy consumption, providing an overview of current trends aimed at improving energy efficiency. We describe how hardware innovations such as energy-efficient processors, novel system architectures, power management techniques, and advanced scheduling policies do have a direct impact on how applications need to be programmed and executed on HPC systems. For application developers, understanding how these new systems work and how to analyse and report the performances of their own software is critical in the dialog with HPC system designers and administrators. The paper aims to raise awareness about energy efficiency among users, particularly in the high energy physics and astrophysics domains, offering practical advice on how to analyse and optimise applications to reduce their energy consumption without compromising on performance.
Asteroid (16) Psyche is a metal-rich body that might record an ancient coherent magnetization if some relict crust or mantle is preserved. Herein, we use magnetohydrodynamic simulations to predict (16) Psyche's field, assuming it has such relicts that were magnetized after nebula dispersal via one of two distinct pathways: i. an early solar wind-induced magnetization imparted after a larger body was impacted, forming the present-day asteroid and ii. a core dynamo magnetization imparted in an asteroid that is either presently largely intact or was a rubble pile. For pathway (i) we find the field to be predominantly dipolar and spin axis-aligned. For pathway (ii) we find the field to be either dipolar and spin axis-misaligned, or highly multipolar. Field topology and orientation may thus reveal key details of the nature and history of (16) Psyche, and our framework is broadly applicable to the study of magnetic fields from other asteroids.
Solders with superconducting properties around $4\,{\rm K}$ are useful in low magnetic field environments for AC current leads or in electrical and mechanical bonds. Accurate knowledge of these properties are needed in high precision experiments. We have measured the electrical resistance of five commercially-available solders: 50\%Sn-50\%Pb, 60\%Sn-40\%Pb, 60\%Sn-40\%Pb-0.3\%Sb, 52\%In-48\%Sn, and 96.5\%Sn-3.5\%Ag, down to $2.3\,{\rm K}$ and in applied magnetic fields from 0 to 0.1$\,{\rm T}$. Their critical temperatures $T_c$ and critical fields $B_c$ were extracted in our analysis, taking into account the observed 90\%-to-10\% transition widths. Our best candidate for low-loss AC current leads in low fields is 50\%Sn-50\%Pb, which had zero-field $T_{c,0} = (7.1 \pm 0.3)\,{\rm K}$, and remained high to $T_c(B=0.1\,{\rm T}) = (6.9 \pm 0.3) \,{\rm K}$. We report $T_c$ and $B_c$ of 60\%Sn-40\%Pb-0.3\%Sb and $B_{c,0}$ of 96.5\%Sn-3.5\%Ag for the first time. Our $T_{c,0}= (3.31 \pm 0.04)\,{\rm K}$ for 96.5\%Sn-3.5\%Ag disagrees with a widely adopted value.