Classical Limit Research Articles

Research on the Hybrid Teaching Mode Combining MOOC and Flipped Classroom in Piano Courses in University

The traditional teaching model of piano courses in universities faces challenges such as insufficient teaching resources, limited class hours, and difficulty in providing personalized guidance, which hinder the effective improvement of students’ learning outcomes and participation. To address these challenges, this study introduces a blended teaching model that combines massive open online course (MOOC) and flipped classrooms. This model integrates the rich resources and flexibility of MOOC with the interactivity and effectiveness of flipped classrooms, aiming to provide a new approach to piano education. The study compares the differences between the traditional and the blended teaching models in terms of knowledge acquisition, improvement in performance skills, and learning satisfaction, using surveys and data analysis for evaluation. The results indicate that the combination of MOOC and flipped classrooms significantly enhances students’ learning outcomes and classroom participation. This study provides a feasible solution for the teaching reform of university piano courses and lays the foundation for improving students’ musical literacy and learning experience.

Quantum probabilistic space analysis for enhanced two-wheeler traffic safety: from classical limitations to advanced quantum circuits

In the increasing traffic scenario and the presence of automated four-wheeler vehicle-like situations, we need to consider the possible safe driving for the two-wheelers also. As two-wheelers need manual balances, embedding the autopilot systems is a tougher task. To resolve this issue, we attempt to address this problem with probability spaces. Then, these classical probability spaces are promoted into quantum probability spaces. The quantum computing aspects such as quantum gates are embedded in the analysis of the quantum probability space. With those quantum computing protocols, various traffic scenarios are calculated, such as the probability of accidents and the avoidance probability of accidents. A set of mathematical lemmas with certain conditions and their proof for mapping classical to quantum probability space and the singularities in this quantum probability space are also discussed in this work.

On the classical limit of the (sub)n-leading soft graviton theorems in D = 4 without deflection

Tree-level gravitational amplitudes satisfy an infinite hierarchy of soft factorization theorems. The existence of these theorems has been recently linked with the existence of an infinite tower of asymptotic symmetries. In this paper, we analyze the relevance of the soft graviton theorems beyond sub-leading order in the context of classical gravitational scattering in four dimensions. More in detail, we show that the infinite impact parameter limit of the late-time gravitational field emitted during a classical scattering can be derived using these factorization theorems. The classical field obtained in this (infinite impact parameter) regime has an expansion in the frequency of the detector where the modes scale as ωn log ω with a vanishing memory.

Needs Analysis: Developing a Digital Literacy Integrated Speaking Syllabus for Arabic Pre-Service Teachers in China

Integrating digital literacy into language teacher preparation programs has gained increasing attention in recent years. With the expanding economic trade with Arab countries, Arabic language education is becoming more important in China. This study aims to identify the needs for developing a digital literacy-integrated speaking syllabus for Arabic pre-service teachers in China. The study presents phase 1: needs analysis of the design and developmental research (DDR) approach. Interviews were conducted to collect data. The finding shows that while digital literacy elements are integrated into the existing speaking syllabus through resources and multimedia presentation teaching approach, it is mainly concentrated on the skill domain rather than the knowledge and attitude domains. The study further found that the challenges for Arabic lecturers to integrate digital literacy are the lack of digital teaching resources, the lack of digital literacy training for lecturers, the heavy teaching tasks but limited class instructional time, and the restrictions of higher education institutional policies. Moreover, Arabic pre-service teachers have basic digital literacy skills for daily use but lack technical knowledge in Arabic and awareness of digital literacy. The results of the study provide valuable insights for curriculum designers and educators for language teacher education programs in China.

Investigating the Perceptions of EFL Instructors in Improving the Oral Proficiency of Saudi EFL Learners—A Case Study of Majmaah University

This study aims to explore and investigate University English as a Foreign Language (EFL) instructors’ perceptions of enhancing and improving EFL learners’ oral proficiency in English classrooms in Saudi Arabia and real-life communication. The researcher used a mixed-method approach to achieve the aim of the study. The quantitative method involves the construction of a structured questionnaire based on the EFL instructors’ views to enhance the students’ oral proficiency and was distributed among 30 EFL teachers from Majmaah University. In the quantitative phase, in-depth interviews were conducted with a subset of 6 EFL instructors to gain deeper insights into EFL instructors’ perceptions of improving EFL learners’ oral proficiency. The findings of the study explored that, EFL instructors at Majmaah University agreed that oral proficiency is the most important aspect of overall language proficiency, and they used various strategies to improve the students’ oral proficiency with a clear preference for role-playing, presentations, group discussions, and debates. The findings also stated some problems and challenges such as limited class time, large class sizes, and low student motivation faced by EFL instructors to improve learners’ oral proficiency. The study finally, recommends including the incorporation of more communicative activities, the integration of technology, and the provision of professional development workshops. The findings of the study can give a path to provide some new strategies to overcome the problems and challenges faced by EFL instructors for enhancing EFL learners’ oral proficiency.

A Combined CNN-LSTM Network for Ship Classification on SAR Images.

Satellite SAR (synthetic aperture radar) imagery offers global coverage and all-weather recording capabilities, making it valuable for applications like remote sensing and maritime surveillance. However, its use in machine learning-based automatic target classification faces challenges, including the limited availability of SAR target training samples and the inherent constraints of SAR images, which provide less detailed features compared to natural images. These issues hinder the effective training of convolutional neural networks (CNNs) and complicate the transfer learning process due to the distinct imaging mechanisms of SAR and natural images. To address these challenges, we propose a shallow CNN architecture specifically designed to optimize performance on SAR datasets. Evaluations were performed on three datasets: FUSAR-Ship, OpenSARShip, and MSTAR. While the FUSAR-Ship and OpenSARShip datasets present difficulties due to their limited and imbalanced class distributions, MSTAR serves as a benchmark with balanced classes. To compare and optimize the proposed shallow architecture, we examine various properties of CNN components, such as the filter numbers and sizes in the convolution layers, to reduce redundancy, improve discrimination capability, and decrease network size and learning time. In the second phase of this paper, we combine the CNN with Long short-term memory (LSTM) networks to enhance SAR image classification. Comparative experiments with six state-of-the-art CNN architectures (VGG16, ResNet50, Xception, DenseNet121, EfficientNetB0, and MobileNetV2) demonstrate the superiority of the proposed approach, achieving competitive accuracy while significantly reducing training times and network complexity. This study underscores the potential of customized architectures to address SAR-specific challenges and enhance the efficiency of target classification.

Automated discovery of experimental designs in super-resolution microscopy with XLuminA

Driven by human ingenuity and creativity, the discovery of super-resolution techniques, which circumvent the classical diffraction limit of light, represent a leap in optical microscopy. However, the vast space encompassing all possible experimental configurations suggests that some powerful concepts and techniques might have not been discovered yet, and might never be with a human-driven direct design approach. Thus, AI-based exploration techniques could provide enormous benefit, by exploring this space in a fast, unbiased way. We introduce XLuminA, an open-source computational framework developed using JAX, a high-performance computing library in Python. XLuminA offers enhanced computational speed enabled by JAX’s accelerated linear algebra compiler (XLA), just-in-time compilation, and its seamlessly integrated automatic vectorization, automatic differentiation capabilities and GPU compatibility. XLuminA demonstrates a speed-up of 4 orders of magnitude compared to well-established numerical optimization methods. We showcase XLuminA’s potential by re-discovering three foundational experiments in advanced microscopy, and identifying an unseen experimental blueprint featuring sub-diffraction imaging capabilities. This work constitutes an important step in AI-driven scientific discovery of new concepts in optics and advanced microscopy.

Classical correspondence beyond the Ehrenfest time for open quantum systems with general Lindbladians

Quantum and classical systems evolving under the same formal Hamiltonian H may exhibit dramatically different behavior after the Ehrenfest timescale tE∼log(ħ-1), even as ħ→0. Coupling the system to a Markovian environment results in a Lindblad equation for the quantum evolution. Its classical counterpart is given by the Fokker–Planck equation on phase space, which describes Hamiltonian flow with friction and diffusive noise. The quantum and classical evolutions may be compared via the Wigner-Weyl representation. Due to decoherence, they are conjectured to match closely for times far beyond the Ehrenfest timescale as ħ→0. We prove a version of this correspondence, bounding the error between the quantum and classical evolutions for any sufficiently regular Hamiltonian H(x, p) and Lindblad functions Lk(x,p). The error is small when the strength of the diffusion D associated to the Lindblad functions satisfies D≫ħ4/3, in particular allowing vanishing noise in the classical limit. Our method uses a time-dependent semiclassical mixture of variably squeezed Gaussian states. The states evolve according to a local harmonic approximation to the Lindblad dynamics constructed from a second-order Taylor expansion of the Lindbladian. Both the exact quantum trajectory and its classical counterpart can be expressed as perturbations of this semiclassical mixture, with the errors bounded using Duhamel’s principle. We present heuristic arguments suggesting the 4/3 exponent is optimal and defines a boundary in the sense that asymptotically weaker diffusion permits a breakdown of quantum-classical correspondence at the Ehrenfest timescale. Our presentation aims to be comprehensive and accessible to both mathematicians and physicists. In a shorter companion paper, we treat the special case of Hamiltonians that decompose into kinetic and potential energy with linear Lindblad operators, with explicit bounds that can be applied directly to physical systems.

Asymptotics of Weil-Petersson volumes and two-dimensional quantum gravities

We propose a refined expression for the large genus asymptotics of the Weil-Petersson volumes of the moduli space of super-Riemann surfaces with an arbitrary number of boundaries. Our formula leverages the connection between JT supergravity and its matrix model definition, utilizing some basic tools of resurgence theory. The final result holds for arbitrary boundary lengths and preserves the polynomial structure of the super-volumes. As a byproduct we also obtain a prediction for the large genus asymptotics of generalized \ThetaΘ-class intersection numbers. We extend our proposal to the case of the quantum volumes relevant for the Virasoro minimal string/Liouville gravity. Performing the classical limit on the quantum volumes, we recover a formula for the ordinary Weil-Petersson building blocks of JT gravity.

Post AdS/CFT

The Hamiltonian governing the gravitational interaction of N relativistic particles in a four-dimensional anti-de Sitter background is derived to leading order in Newton’s constant. The resulting pairwise interactions, combined with the confining nature of motion in anti-de Sitter spacetime, are expected to lead to classical chaos. In the context of the AdS/CFT correspondence, the emergence of a chaotic classical limit on the gravity side has important implications for the dual three-dimensional conformal field theory, including that the spectrum of conformal primary operators at strong coupling should exhibit level repulsion in line with the Wigner surmise.

Smooth zero entropy flows satisfying the classical central limit theorem

Smooth zero entropy flows satisfying the classical central limit theorem

Probabilistic Analysis of Slope Stability Considering Random Fields

The study of slope stability is of paramount importance for society, as it enables the evaluation of slope security and the establishment of alert parameters to mitigate financial losses and, in severe cases, prevent human casualties. Improving alert criteria necessitates a comprehensive assessment not only of the slope's safety factor but also its probability of failure. Therefore, the use of probabilistic techniques becomes imperative, with the Monte Carlo Method (MCM) emerging as a prevalent choice in geotechnical investigations. Employing MCM for slope stability involves modeling the target profile while varying crucial material parameters—such as friction angle, cohesion, and specific weight—in each iteration. As a result, the outcome yields a distribution of safety factors, aiding in the assessment of both average safety levels and failure probabilities. Failure probability is determined by counting simulations with safety factors below unity. Conventional approaches identified in the literature often employ uniform profiles in successive rounds, overlooking the spatial distribution of parameters. Hence, this study introduces a case analysis where failure probability is quantified through MCM, integrating random fields in each iteration. For assessing variability, the PLAXIS software was utilized, employing classical limit equilibrium methods alongside the LAS technique (Local Average Subdivision). This facilitates a comparative analysis of probabilities derived from distinct equilibrium methodologies. The case study will focus on a slope within Brazilian territory, where a comprehensive geotechnical survey encompassing field and laboratory assessments has been conducted.

Hamiltonian for complex plasmas

The Hamiltonian for a complex plasma involving dust spinning motion in a magnetic field is proposed. The formulation is in a classical limit of a quantum mechanical approach based on the Dirac equation, a relativistic wave equation in which the spin of particles is considered. The quantum mechanical spin term –γs·B [γ=gq/2m, g=2(Lande´ g−factor),q is a charge, m is a mass of a particle, and s = spin operator] is replaced by –γs·B [γ with g=1, s = I(ω+γB), I is the moment of inertia of a dust particle, and ω is the spinning angular velocity of a dust particle] in a classical limit. The wave–particle interaction involving spin motion is described as an interaction between particles and quasiparticles by the second quantization. The equation of motion with a damping term shows the relaxation of spinning dust particles aligning with the magnetic field.

Non-linearity and chaos in the kicked top

Classical chaos arises from the inherent non-linearity of dynamical systems. However, quantum maps are linear; therefore, the definition of chaos is not straightforward. To address this, we study a quantum system that exhibits chaotic behavior in its classical limit: the kicked top model, whose classical dynamics are governed by Hamilton’s equations on phase space, whereas its quantum dynamics are described by the Schrödinger equation in Hilbert space. We explore the critical degree of non-linearity signifying the onset of chaos in the kicked top by modifying the original Hamiltonian so that the non-linearity is parameterized by a quantity p. We find two distinct behaviors of the modified kicked top depending on the value of p. Chaos intensifies as p varies within the range of 1≤p≤2, whereas it diminishes for p>2, eventually transitioning to a purely regular oscillating system as p tends to infinity. We also comment on the complicated phase space structure for non-chaotic dynamics. Our investigation sheds light on the relationship between non-linearity and chaos in classical systems, offering insights into their dynamical behavior.

Validation of Impact Forces Estimated by Wearable Device VERT in Volleyball.

De Bleecker, C, Vermeulen, S, Willems, T, Segers, V, Spanhove, V, Leys, R, Vanrenterghem, J, and De Ridder, R. Validation of impact forces estimated by wearable device VERT in volleyball validation impact forces VERT. J Strength Cond Res XX(X): 000-000, 2024-As volleyball players are exposed to high volumes of forceful jump-landing actions, the risk of injuries is increased. Wearable technology such as the VERT device offers a promising avenue for load monitoring of volleyball players, potentially allowing better control of intensity of training and matches to minimize the likelihood of injuries. Although validity of jump counts and jump height is well investigated, studies validating impact forces estimated by VERT device referenced to force plate data are scarce. The objective of this study was to validate the use of VERT for the estimation of impact forces during volleyball. Twenty-one volleyball players of different levels performed countermovement jumps (CMJ), block jumps, spike jumps, and a set with a combination of several volleyball jump-landing tasks. Impact forces estimated by VERT were compared with resultant force values measured using a force plate. A total of 221 spike jumps, 286 block jumps, and 203 CMJ were analyzed. Given the identified proportional bias and heteroscedasticity, an adapted Bland-Altman plot featuring the line of best fit and V-shaped 95% confidence intervals instead of classic limits of agreement was created. Furthermore, our results suggest a proportional bias between the 2 measurements, with the VERT sensor tending to overestimate impact forces compared with the force plate, increasingly at higher mean values. Therefore, the VERT algorithm has not been proven valid for quantifying impact forces. However, a correction factor is proposed to obtain better results for impact forces estimated by VERT, making it suitable for implementation in sport contexts.

Chemical Sensing Using Thermocouple Cantilevers: Pushing Toward Quantum Sensing

Detecting and quantifying minuscule quantities of chemicals with high molecular selectivity remains a measurement challenge. We present a photothermal spectroscopic method that exploits the Seebeck effect in a finely engineered nanoscale thermocouple junction at the apex of a microcantilever. The temperature variations driving this thermoelectric effect are induced by the nonradiative decay of molecular adsorbates, efficiently excited by a tunable infrared source. This approach not only benefits from an extremely small thermal mass and superior thermal insulation but also achieves an atto-gram detection limit. The simplicity and compactness of its electronic readout further enhance the method's applicability. In this work, we demonstrate the detection of photothermal spectra for physisorbed trinitrotoluene (TNT) and dimethyl methylphosphonate (DMMP) molecules, as well as representative polymers, with estimated masses as small as 10-18 grams. Our findings underscore the potential of classical measurement techniques to approach the sensitivity and selectivity limits required for molecular detection. Establishing such classical limits is an important part of transitioning into the quantum-sensing regime, which aims to explore new enhancements in sensitivity and selectivity in chemical sensing beyond the conventional limits.

Protonation of Metal Oxides By Charge-Transfer-Protonation

Proton-conducting oxides are typically structured based on a perovskite-type arrangement in the formula of ABO3, which is modified by partially substituting a lower valence cation M than the original, resulting in AB1-xMxO3-δ. Such modification induces oxygen vacancies in the lattice due to electrical neutrality and is accompanied by the hydration of these vacancies to enable proton dissolution in the material.In this approach, (i) hydration of oxygen vacancies and (ii) ambipolar diffusion of protons and oxide ions must occur simultaneously for complete material protonation. However, (i) necessitates a thermodynamically low temperature, whereas (ii) requires a kinetically high temperature. One reason why proton conductivity has been reported for only a limited class of materials may be attributed to this temperature dilemma. Expanding the working temperature range of proton conductors is crucial for practical applications. Currently, few materials can achieve sufficient proton conductivity in the 300-400°C temperature range. However, there might be examples of materials that fulfill (i) in this temperature range but face kinetic limitations in (ii).Given the above considerations, we have explored an alternative charge-transfer protonation method for material protonation, which we experimentally investigated.Charge Transfer Protonation (hereafter abbreviated as CTP) is a mechanism where a metal oxide is doped with a transition metal M, capable of multiple valences, and the material is protonated using the valence change of M. During material baking in air, M undergoes oxidation, transitioning to a higher valence state, corresponding to a stage in the conventional mechanism where (i) oxygen vacancy diffusion is complete. Subsequent exposure of the baked sample to hydrogen results in M reduction, facilitating (ii) proton dissolution. Since the high-temperature process (i) is completed during baking, CTP is anticipated to protonate materials resistant to conventional methods due to thermodynamic constraints and enable existing proton-conducting oxides to function at lower temperatures.This report presents the results of an investigation utilizing SrZrO3 as a matrix and Mn as a dopant capable of valence change to elucidate the operation principle of the CTP mechanism.Experimental:SrZr0.9Mn0.1O3-δ was synthesized using the solid-state reaction method. Samples with varying porosities were prepared to assess the progress of the CTP mechanism, with porosity controlled by firing temperature. Protonation by this mechanism was investigated by measuring conductivity in Ar and 100% H2 at temperatures ranging from 200°C to 900°C and comparing the results using the AC impedance method.Results and Discussion:Conductivity measurements were conducted in Ar and H2 to assess whether the nearly dense SrZr0.9Mn0.1O3-δ sintered sample could be protonated via CTP. Higher conductivity was observed in H2 compared to Ar, except at high temperatures, indicating the potential protonation of SrZr0.9Mn0.1O3-δ by CTP. However, the conductivity in H2 was lower than anticipated. In response, we hypothesized that only the material surface was protonated and examined SrZr0.9Mn0.1O3-δ samples with different porosities. Results showed a greater disparity between Ar and H2 conductivity in samples with higher porosity, suggesting broader proton dissolution in porous materials. Proton dissolution primarily occurred at the interface between hydrogen gas and the sample, with significantly increased conductivity observed in porous materials, indicative of complete proton dissolution at the material surface.

Quantizations of transposed Poisson algebras by Novikov deformations

Abstract The notions of the Novikov deformation of a commutative associative algebra and the corresponding classical limit are introduced. We show such a classical limit belongs to a subclass of transposed Poisson algebras, and hence the Novikov deformation is defined to be the quantization of the corresponding transposed Poisson algebra. As a direct consequence, we revisit the relationship between transposed Poisson algebras and Novikov–Poisson algebras due to the fact that there is a natural Novikov deformation of the commutative associative algebra in a Novikov–Poisson algebra. Hence all transposed Poisson algebras of Novikov–Poisson type, including unital transposed Poisson algebras, can be quantized. Finally, we classify the quantizations of 2-dimensional complex transposed Poisson algebras in which the Lie brackets are non-abelian up to equivalence.

Gravitational Bremsstrahlung in black-hole scattering at OG3: linear-in-spin effects

We compute the far-field time-domain waveform of the gravitational waves produced in the scattering of two spinning massive objects. The results include linear-in-spin (S) couplings and first-order gravitational corrections (G3), and are valid for encounters in the weak-field regime. Employing a field-theory framework based on the scattering of massive scalar and vector particles coupled to Einstein-Hilbert gravity, we derive results for leading and the next-to-leading spectral waveforms. We provide analytic expressions for the required scattering data, which include trees, one-loop amplitudes and their cuts. The expressions are extracted from numerical amplitude evaluations with the Caravel program, using analytic reconstruction techniques applied in the classical limit. We confirm a recent prediction for infrared physics of the classical observable, and observe the surprising appearance of a ultraviolet singularity, which drops out in the far-field waveform.

Placental Abruption: Pathophysiology, Diagnosis, and Management.

Placental abruption is a complete or partial separation of the placenta from the uterine decidua. Clinical manifestations include vaginal bleeding, abdominal pain, uterine contractions, and abnormalities in the fetal heart rate tracing. Placental abruption occurs in 0.4% to 1.0% of all pregnancies. However, the pathophysiology remains incompletely understood. We present a review of the pathophysiology, diagnosis, and management of placental abruption, exploring overlapping processes which contribute to premature placental separation. Classic findings and limitations of ultrasound in evaluating placental abruption are explained. Finally, we discuss the management of placental abruption based on gestational age, fetal status, and maternal hemodynamic stability.