Miracle-dz/UniFAR-FTUs huggingface dataset:
Interplay between mathematics and physics to catch the nature of a scientific breakthrough: The case of the blackbody

This paper aims to provide a contribution to the research in physics education regarding the interplay between mathematics and physics in teaching and learning physics at the university level. The argument is developed through a study focused on the historical case study of the blackbody that led Planck to make one of the most significant scientific breakthroughs in physics: the introduction of discreteness and quantization into physical processes. The study is methodologically guided by the model that Udhen, Karam, Pietrocola, and Pospiech elaborated to highlight the interplay between physics and mathematics within teaching and learning practices [O. Uhden, R. Karam, M. Pietrocola, and G. Pospiech, Modelling mathematical reasoning in physics education, Sci. Educ. Netherlands 21 , 485 (2012). ]. The model emphasizes the distinction between the technical and structural roles of mathematics in physics, with the latter role being argued to correspond to processes of mathematization and interpretation. We used this model to analyze Planck ’ s original papers and to reconstruct the reasoning that, thanks to the structural role played by mathematics, paved the way for the quantistic scientific breakthrough. The results of the analysis led us to design a teaching tutorial that we implemented with mathematics and physics university students. Students ’ reactions are reported to discuss the educational potential of the approach beyond the specific case and to argue for its potential general application to other similar physics topics. DOI: 10.1103/PhysRevPhysEducRes.15. 020130
D’Yakov–Kontorovich instability in planar reactive shocks

The standard D’Yakov and Kontorovich (DK) instability occurs when a planar shock wave is perturbed and then oscillates with constant amplitude in the long-time regime. As a direct result, pressure perturbations generated directly behind the shock propagate downstream as non-evanescent sound waves, an effect known as spontaneous acoustic emission (SAE). To reach the DK regime, the slope of the Rankine–Hugoniot curve in the post-shock state must satisfy certain conditions, which have usually been related to non-ideal equations of state. This study reports that the DK instability and SAE can also occur in shocks moving in perfect gases when exothermic effects occur. In particular, a planar detonation, initially perturbed with a wavelength much larger than the detonation thickness, may exhibit constant-amplitude oscillations when the amount of heat released is positively correlated with the shock strength, a phenomenon that resembles the Rayleigh thermoacoustic instability. The opposite strongly damped oscillation regime is reached when the shock strength and the change in the heat released are negatively correlated. This study employs a linear perturbation model to describe the long-time and transient evolution of the detonation front, which is assumed to be infinitely thin, and the sound and entropy–vorticity fields generated downstream.
Best Proximity Results with Applications to Nonlinear Dynamical Systems

Best proximity point theorem furnishes sufficient conditions for the existence and computation of an approximate solution ω that is optimal in the sense that the error σ ( ω , J ω ) assumes the global minimum value σ ( θ , ϑ ) . The aim of this paper is to define the notion of Suzuki α - Θ -proximal multivalued contraction and prove the existence of best proximity points ω satisfying σ ( ω , J ω ) = σ ( θ , ϑ ) , where J is assumed to be continuous or the space M is regular. We derive some best proximity results on a metric space with graphs and ordered metric spaces as consequences. We also provide a non trivial example to support our main results. As applications of our main results, we discuss some variational inequality problems and dynamical programming problems.
Bidirectional Reconnection Outflows in an Active Region

We report on bidirectional coronal reconnection outflows reaching ±200 km s−1 as observed in an active region with the Si iv and C ii spectra of the Interface Region Imaging Spectrograph (IRIS). The evolution of the active region with an emerging flux, a failed filament eruption, and a jet is followed in Solar Dynamical Observatory (SDO)/Atmospheric Imaging Assembly (AIA) filters from 304 to 94 Å, IRIS slit jaw images, and SDO/Helioseismic and Magnetic Imager movies. The bidirectional outflow reconnection is located at a bright point visible in multiwavelength AIA filters above an arch filament system. This suggests that the reconnection occurs between rising loops above the emergence of magnetic bipoles and the longer, twisted magnetic field lines remnant of the failed filament eruption one hour before. The reconnection occurs continuously in the corona between quasi-parallel magnetic field lines, which is possible in a 3D configuration. The reconnection also triggers a jet with transverse velocities around 60 km s−1. Blueshifts and redshifts along its axis confirm the existence of a twist along the jet, which could have been transferred from the filament flux rope. The jet finally blows up the material of the filament before coming back during the second phase. In the Hα Dopplergrams provided by the MSDP spectrograph, we see more redshift than blueshift, indicating the return of the jet and filament plasma.
Effects on auditory function of chronic exposure to electromagnetic fields from mobile phones

The widespread use of mobile phones has given rise to apprehension regarding the possible hazardous health effects of high-frequency electromagnetic fields (EMFs) on auditory function. We conducted a study to investigate the effects of long-term (>4 yr) exposure to EMFs emitted by mobile phones on auditory function. My study population was made up of 40 healthy medical students—31 men and 9 women, aged 20 to 30 years (mean 22.7). Of this group, 31 subjects typically held their phone to the right ear and 9 to the left ear; the non–phone-using ear served as each subject’s control ear. The phone-using subjects were also split into two groups of 20 based on the duration of their daily phone use (≤60 min vs. >60 min). All subjects underwent pure-tone audiometry, speech audiometry, impedance audiometry, and brainstem evoked response audiometry (BERA), and comparisons were made between the phone-using ear and the control ear and between the shorter and longer duration of daily use. We found no statistically significant differences in high-frequency pure-tone average between the phone using ears and the control ears (p = 0.69) or between the shorter- and longer-duration phone-using ears (p = 0.85). Moreover, statistical analysis of BERA findings revealed no significant differences between the phone-using ears and the control ears in terms of wave I-III, III-V, and I-V interpeak latencies (p = 0.59, 0.74 and 0.44, respectively). None of the subjects reported any subjective symptoms, such as headache, tinnitus, or sensations of burning or warmth behind, around, or on the phone-using ear. I conclude that long-term exposure to EMFs from mobile phones does not affect auditory function.
The Gauss-Siedel (GS) and the Jacobian-free Newton-Krylov (JFNK) methods applied to steady 2D buoyancy convection in vertical cylinders

Investigated are the Gauss-Siedel (GS) and the Jacobian-Free Newton-Krylov (JFNK) methods for solving the transport equations for buoyancy-induced circulation of and heat transfer through Newtonian fluids in vertical cylinders. The domain has rigid walls. Heat enters from below, cooling is at the top and the vertical wall is insulated. The system parameters are the aspect ratio (radius/height, a) and Rayleigh number (Ra) considered in combinations (a, Ra) of (1, 8(103)), (2, 105) and (4, 1.6(105)). The Prandtl number (Pr) for the fluid was 7. The equations were formulated in terms of the stream function, vorticity and temperature, and discretized using both central and monotonic conservative finite difference schemes of second order accuracy. The initial conditions for temperature at internal nodes and the grid size were varied. Solutions by parallel implementation of the GS method were fast and stable. The JFNK method, when it converged, was significantly slower and it sometimes produced different and/or additional solutions relative to the GS method. When the different JFNK-produced solutions were used as initial conditions for the GS method, the solutions reverted to original GS results to suggest that some JFNK solutions are unstable.
Monadic involutive pseudo-BCK algebras.

In this paper we introduce and study the monadic involutive pseudo-BCK algebras (porims). As particular cases we obtain the monadic involutive pseudo-BCK(pP) lattices (pseudo-residuated lattices), monadic pseudo-IMTL algebras, monadic pseudo-NM algebras, monadic pseudo-MV algebras, etc. and all the commutative corresponding algebras. 2000 Mathematics Subject Classification: 03G25, 06F05, 06F35.
Onset and Evolution of the Oblique, Resonant Electron Firehose Instability in the Expanding Solar Wind Plasma

A double adiabatically expanding solar wind would quickly develop large parallel to perpendicular temperature anisotropies in electrons and ions that are not observed. One reason is that firehose instabilities would be triggered, leading to an ongoing driving/saturation evolution mechanism. We verify this assumption here for the first time for the electron distribution function and the electron firehose instability (EFI), using fully kinetic simulations with the Expanding Box Model. This allows the self-consistent study of onset and evolution of the oblique, resonant EFI in an expanding solar wind. We characterize how the competition between EFI and adiabatic expansion plays out in high- and low-beta cases, in high- and low-speed solar wind streams. We observe that, even when competing against expansion, the EFI results in perpendicular heating and parallel cooling. These two concurrent processes effectively limit the expansion-induced increase in temperature anisotropy and parallel electron beta. We show that the EFI goes through cycles of stabilization and destabilization: when higher wave number EFI modes saturate, lower wave number modes are destabilized by the effects of the expansion. We show how resonant wave/ particle interaction modifies the electron velocity distribution function after the onset of the EFI. The simulations are performed with the fully kinetic, semi-implicit expanding box code EB-iPic3D.
Stationary Solutions for Nonlinear Schrödinger Equations by Lie Group Analysis

The theory of nonlinear Schrödinger equations (NLSE) plays a vital role in various areas of physical, biological, and engineering sciences. The governing NLSE shows up in distinctive fields, including fluid dynamics, nonlinear optics and plasma physics. A lot of work has been done to find soliton solutions for various forms of NLSEs [1–20]. Eslami and Neirameh studied the exact soliton solutions for higher order NLSE [13]. Biswas found the bright and dark soliton solution in optical fiber under parabolic law of non-linearity [12]. Yang et al. studied fourth order variable coefficient NLSE for obtaining bright soliton interaction [1]. Aouadi et al. obtained W -shaped, dark, and bright soliton for Biswas-Arshed equation [7]. Zhou et al. studied Triki-Biswas equation for chirped singualr solitons [8]. Zhou et al. also obtained optical solitons for unstable NLSE [9]. Inc et al. obtained the optical solitons and modulation instability analysis of an integrable model of (2+1)-Dimensional Heisenberg ferromagnetic spin chain equation [15]. Khalique and Biswas found the solution of NLSE with non-Kerr law non-linearity [17]. Ekici et al. found the optical solitons with DWDM technology and four-wave mixing [14]. Zhang et al. studied the interactions of vector antidark solitons for the coupled nonlinear Schrödinger equation in inhomogeneous fibers [19]. Biswas and Khalique found the stationary solutions for the nonlinear dispersive Schrödinger equation (NDSE) which is an important generalized form of NLSE [10] and later on they also obtained the stationary solutions for NDSE with generalized evolution [11]. Here, we will find the stationary solutions of three important NLSEs, namely, GerdjikovIvanov equation, cubic-quintic equation, and paraxial equation.
MU : a domain-independent case-based expert system

MU: A Domain-Independent Case-Based Expert System Mitchell Jay Sklar 1988 A medical expert system is a computer program designed to function in the role of a medical consultant. In many such systems described in the literature, the knowledge base of the program is stored in the form of production rules or frames. While these approaches have their advantages, there exist alternative cognitive models as well. We describe MU, an expert system built around a case-based reasoning model. MU’s knowledge base is composed of recollections of particular patients or groups of patients, stored flexibly in a format that allows virtually any type of description the user desires. This flexible storage, together with the separation of the database from the mechanics of the inference engine, provides MU with domain independence. MU is also less goal-directed than traditional medical expert systems, relying instead on associational reasoning to produce a varied output of recollections, weighted judgements, conclusions, commentary, and guesses, in a process we term musing. Preliminary tests of MU with psychiatric and mammographic cases produced good results, but final evaluation of the system awaits comprehensive trials with larger databases.
Near-Field Measurement and Calibration Technique for RF EMF Exposure Assessment of mm-wave 5G Devices

Accurate and efficient measurement techniques are needed for exposure assessment of 5G portable devices---which are expected to utilize frequencies beyond 6 GHz---with respect to the radio frequency electromagnetic field exposure limits. Above 6 GHz, these limits are expressed in terms of the incident power density, thus requiring that the electromagnetic fields need to be evaluated with high precision in close vicinity to the device under test (DUT), i.e., in the near-field region of the radiating antenna. This work presents a cutting-edge near-field measurement technique suited for these needs. The technique---based on source reconstruction on a predefined surface representing the radiating aperture of the antenna---requires two sets of measurements; one of the DUT, and one of a small aperture. This second measurement functions as a calibration of both the measurement probe impact on the received signal, and the experimental setup in terms of the relative distance between the probe and the DUT. Results are presented for a 28 GHz and a 60 GHz antenna array; both developed for 5G applications. The computed power density agrees well with simulations at evaluation planes residing as close as one fifth of a wavelength away from the DUT.
The environment of C- and S-shaped radio galaxies

We study the environment of radio galaxies with different morphological types using the Proctor sample, which was built from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey archive. Among the 15 radio galaxy types classified by Proctor, 199 C-shaped (i.e., wide- or narrow-angle tail) and 203 S-shaped (i.e., S- or Z-shaped) sources are selected in this work, which are located in the redshift range of 0.02 < z < 1, because these two subsamples are relatively larger than the other subsamples in the Proctor sample. By cross-matching these radio galaxies with the optical sources drawn from the Sloan Digital Sky Survey (SDSS) database and counting the SDSS sources with an r-band absolute magnitude brighter than −19 located within a 0.5 Mpc distance around each source (i.e., the richness), we find that the fraction of C-shaped sources with a richness above 10 is larger than that of S-shaped sources. We have also correlated the radio galaxies in our sample with the brightest cluster galaxies (BCGs) defined in the NASA/IPAC Extragalactic Database (NED), and infer that the C-shaped sources are more likely to be BCGs than the S-shaped sources. These results support the idea that C-shaped radio galaxies often reside in a richer environment than radio galaxies with other morphological types.
Two Sets of Dynamic Stretching of the Lower Body Musculature Improves Linear Repeated-Sprint Performance in Team-Sports.

Background: Warm-up including dynamic stretching is a popular and widely accepted practice as a pre-exercise routine for athletes. However, a shortage of studies investigating the impact of dynamic stretching on linear repeated-sprint performance exists. Objectives: The present study aims to look at the effect of different volumes of dynamic stretching on 30 m linear repeated sprint performance in team sport athletes. Methods: Fifteen male university team-sport players [age (mean ± SD) 22.1 ± 0.6 years, stature 166.9 ± 6.6cm and body mass 67.5 ± 8.0kg] underwent 3 sessions in this within-subjects counterbalanced study. All sessions included a general warm-up (5-minutes self-paced), followed by a dynamic stretching protocol (one set-DSS1; two sets-DSS2; three sets-DSS3) comprised of five active dynamic exercises for lower body musculature (gastrocnemius, gluteals, hamstrings, quadriceps and hip extensor). A standardized specific warm-up was then undertaken followed by a repeated-sprint test (6 × 30-m sprint with 30 seconds active recovery). Results: Values for average sprint time (AST) and total sprint times (TST) were significantly faster (P = 0.005) following DSS2 compared to DSS1 and DSS3. Fatigue index (FI) was significantly lower in DSS2 compared to DSS1 and DSS3 (P < 0.0005). Heart rate responses and blood lactate also showed significantly lower (P < 0.05) values during the repeated sprint test in DSS2. No differences were established (P > 0.05) for best sprint time (BST), mean sprint time (MST) or rating of perceived exertion (RPE). Conclusions: In conclusion, a dynamic warm-up consisting of two sets resulted in improved performance in repeated-sprint. The exact mechanisms associated with this established ergogenic benefit is still unclear and requires more research.
Toward an AI Physicist for Unsupervised Learning

We investigate opportunities and challenges for improving unsupervised machine learning using four common strategies with a long history in physics: divide and conquer, Occam's razor, unification, and lifelong learning. Instead of using one model to learn everything, we propose a paradigm centered around the learning and manipulation of theories, which parsimoniously predict both aspects of the future (from past observations) and the domain in which these predictions are accurate. Specifically, we propose a generalized mean loss to encourage each theory to specialize in its comparatively advantageous domain, and a differentiable description length objective to downweight bad data and "snap" learned theories into simple symbolic formulas. Theories are stored in a "theory hub," which continuously unifies learned theories and can propose theories when encountering new environments. We test our implementation, the toy "artificial intelligence physicist" learning agent, on a suite of increasingly complex physics environments. From unsupervised observation of trajectories through worlds involving random combinations of gravity, electromagnetism, harmonic motion, and elastic bounces, our agent typically learns faster and produces mean-squared prediction errors about a billion times smaller than a standard feedforward neural net of comparable complexity, typically recovering integer and rational theory parameters exactly. Our agent successfully identifies domains with different laws of motion also for a nonlinear chaotic double pendulum in a piecewise constant force field.
EMC Simulation Based on FDTD Analysis Considering Uncertain Inputs with Arbitrary Probability Density

─ Stochastic Galerkin Method, a prevailing uncertainty analysis method, has been successfully used in today’s EMC simulation, in order to consider nonideality and unpredictability in actual circumstance. In this case, the inputs of the simulation are no longer certain values, but random variables with corresponding probability density distribution. This paper focuses on the arbitrary probability density cases at inputs. Two constructing orthogonal basis methods, the Wiener Haar expansion and the Stieltjes procedure, are generalized into the Stochastic Galerkin Method which is combined with the Finite Difference Time Domain analysis. With the help of the Feature Selective Validation, the quantitative precision comparison of the proposed methods in different cases (the probability density function is continuous or discontinuous) can be presented in detail. Index Terms ─ Arbitrary probability density, EMC simulation, FDTD analysis, stochastic Galerkin method, uncertainty analysis.
Better Confidence Intervals for RMSEA in Growth Models given Nonnormal Data

Currently, the best confidence interval (CI) for RMSEA in covariance structure analysis given nonnormal data is proposed by Brosseau-Liard, Savalei, and Li (BSL). A key assumption for the BSL CI often overlooked is that all the nonzero eigenvalues are equal in a matrix related to the model and data nonnormality. This assumption rarely holds in practice, especially for mean and covariance structure analysis, and violating this assumption can entail serious mistakes when the model’s degrees of freedom are small. One important application of moment structure analysis with small degrees of freedom is growth models. In this paper, we propose a new CI method for RMSEA in growth models given nonnormal data, without assuming equal eigenvalues. Although we focus on growth models, our method applies to any other models in moment structure analysis. Simulation results verify the new method is trustworthy and better than all the current methods.
Long-term multiobject tracking using alternative correlation filters

We propose a real-time multiobject-tracking approach that is minimally affected by environmental conditions and target appearance change. The aim of the proposed approach is to track any object in a scene, regardless of object type, since tracking all of the objects in a scene is critical and widely used in surveillance applications. Thus, motion detection results are used to initialize the trackers. The proposed object-tracking approach is realized with two types of independent correlation filters estimating location and scale. Alternative correlation filters representing different appearances of the target are also proposed in order to increase the robustness of the approach to scene and target changes. Tracking sustainability is provided by putting alternative correlation filters into use when the quality of the tracking output decreases to a critical level. Motion blobs are also used to minimize object boundary drift, which is a challenging problem, especially for long-term tracking. The proposed approach was tested on an object-tracking benchmark dataset and outperformed most state-of-the-art methods.