bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrostatic potential of a uniformly charged annulus
Authors: Ciftja Orion , Bentley Jr Cleo L 
Published: February 2024

Abstract
The calculation of the electrostatic potential and/or electrostatic field due to a continuous distribution of charge is a well-covered topic in all calculus-based undergraduate physics courses. The most common approach is to consider bodies with uniform charge distribution and obtain the quantity of interest by integrating over the contributions from all the differential charges. The examples of a uniformly charged disk and ring are prominent in many physics textbooks since they illustrate well this technique at least for special points or directions of symmetry where the calculations are relatively simple. Surprisingly, the case of a uniformly charged annulus, namely, an annular disk, is largely absent from the literature. One might speculate that a uniformly charged annulus is not extremely interesting since after all, it is a uniformly charged disk with a central circular hole. However, we show in this work that the electrostatic potential created by a uniformly charged annulus has features that are much more interesting than one might have expected. A uniformly charged annulus interpolates between a uniformly charged disk and ring. However, the results of this work suggest that a uniformly charged annulus has such electrostatic features that may be essentially viewed as ring-like. The ring-like characteristics of the electrostatic potential of a uniformly charged annulus are evident as soon as a hole is present no matter how small the hole might be. The solution of this problem allows us to draw attention to the pedagogical aspects of this overlooked, but very interesting case study in electrostatics. In our opinion, the problem of a uniformly charged annulus and its electrostatic properties deserves to be treated at more depth in all calculus-based undergraduate physics courses covering electricity and magnetism.
Recovering coefficients in a system of semilinear Helmholtz equations from internal data
Authors: Ren Kui , Soedjak Nathan 
Published: February 2024

Abstract
We study an inverse problem for a coupled system of semilinear Helmholtz equations where we are interested in reconstructing multiple coefficients in the system from internal data measured in applications such as thermoacoustic imaging. The system serves as a simplified model of the second harmonic generation process in a heterogeneous medium. We derive results on the uniqueness and stability of the inverse problem in the case of small boundary data based on the technique of first- and higher-order linearization. Numerical simulations are provided to illustrate the quality of reconstructions that can be expected from noisy data.
Beam hardening correction based on image noise statistics
Authors: Burkhard Simon , Küng Alain 
Published: February 2024

Abstract
Beam hardening artefacts in x-ray computed tomography (CT) result from energy-dependent attenuation of x-rays in matter and cause inaccuracies in reconstructed 3D volume data. Effects due to beam hardening can easily be corrected if the detected spectrum of x-rays is known after having passed through an object. Conventional scintillator x-ray detectors, however, are incapable of measuring spectral information directly. The innovative idea of this paper is to extract information about the detected spectrum from image noise statistics and to estimate the spectrum using a new semi-empirical model function for a partially absorbed x-ray spectrum depending on a single unknown variable. The beam hardening correction factor is thus determined for each image pixel prior to the 3D reconstruction, does not require knowledge of the material of the CT-scanned object and is determined by modelling physical effects directly, without relying on an iterative approach or elaborate image processing.
Foliation, topology and nucleon charge profiles in hypersphere soliton model
Authors: Hong Soon-Tae 
Published: February 2024

Abstract
In the hypersphere soliton model (HSM), we study the geometrical inner structures and the ensuing charge distributions of the nucleons by exploiting the aspect of the HSM where the hypersphere soliton is described by an extended object possessing the parameter λ (0 ≤ λ < ∞ ) which corresponds to the radial distance from the center of S
3 to the foliation leaves of the hypersphere soliton. To do this, we investigate the foliation and topology related with geometry on a hypersphere described by (μ, θ, ϕ). Exploiting the so-called scanning algorithm we study geometrical relations between spherical shell foliation leave on a northern hemi-hypersphere

S

+

3

and that on a flat equatorial solid sphere E
3 which contains the center of S
3. We then elucidate the physical meaning of μ in S
3 of radius λ by showing that μ plays the role of an auxiliary angle to fix the radius

λ
sin
μ

of the S
2 spherical shell sharing the center of S
3( = S
2 × S
1), at a given angle μ. Next, using the charge density profiles of nucleons with μ dependence, we construct the nucleon fractional charges of spherically symmetric and nontrivial distributions. In the HSM we note that the proton and neutron charges do not leak out from the hypersphere soliton, and the positive and negative charges in the neutron are confined inside and outside its core, respectively. Explicitly we predict the fractional volumes and charges of the neutron. The proton and neutron are shown to be described by a topological structure of two Hopf-linked Möbius strip type twist circles in S
3. We also note that the characteristic ratio of the hypersphere volume to the corresponding solid sphere one is given by a geometrical invariant related with hyper-compactness.
Mechanical characteristics and thermal conductivity of defect single-layer buckled honeycomb germanene
Authors: Tseng Po-Han , Bui Thi-Xuyen , Lu Yu-Sheng , Chen Fang-Yi , Lin Ming-Hong , Fang Te-Hua 
Published: February 2024

Abstract
This study uses molecular dynamics (MD) simulation to investigate the defect rate, defect morphology, and different temperature effects on the mechanical properties, deformation behavior, and thermal conductivities of a single layer of germanene nanosheets via a tensile process. Samples are squeezed in the middle, leading to filling in minor defects. Young’s modulus and yield strength decrease with increasing temperature and defect rates. Young’s modulus in the armchair direction is larger than that in the zigzag direction, with the samples with a random porosity of 0%and 2% and smaller than the model with a random porosity of 4% to 10%. Young’s modulus in the armchair direction is larger than in the zigzag order with all the different pore shapes. The yield strength in the armchair direction is smaller than that in the zigzag at all temperatures, all different pore shapes, and all defect rates except for the sample with a random porosity of 2%. The thermal conductivity depends on the sample direction, the defect morphologies due to the shrinkage of membranes are complicated, and all are smaller than the thermal conductivity of a perfect sample. The thermal conductivity of the perfect sample is highest at 300 K.
R-z plane spatial critical current inhomogeneity-induced mechanical response of GdBCO superconducting bulks during field cooling magnetization
Authors: Hu J T , Yang W J , Zhou D F , Zhao P , Deng F W , Yan J Z 
Published: February 2024

Abstract
Benefiting from the high critical current density (J
c), single-grain (RE)BCO (where RE = rare earth or Gd) bulks are capable of trapping over 17.6 T magnetic field which is crucial for the application of bulk superconductors. Nevertheless, during field cooling magnetization (FCM), the large mechanical stress induced by Lorentz forces may lead to fracture behavior in the brittle ceramic nature of (RE)BCO materials. Most previous numerical models that adopted simplified homogeneous J
c had difficulty reflecting the real stress/strain situation in high temperature superconductor (HTS) bulks. Based on the proposed modified Jirsa model considering r-z plane J
c inhomogeneity, we investigate the mechanical response of GdBCO bulks manufactured by top-seeded melt growth (TSMG) process. A 2D axisymmetric electromagnetic-thermal-mechanical coupled model is implemented to take into account the dependence of J
c upon mechanical deformation. The simulation results show the electromagnetic-thermal-mechanical response of the r-z plane inhomogeneous J
c model is lower than that obtained by the homogeneous J
c model. This confirms Takahashi’s speculation (K Takahashi 2019 Supercond. Sci. Technol.
32 015007) about the mismatch between experimental data and the simulation results of homogeneous J
c model, and suggests the stress levels in the bottom plane of HTS bulk are overestimated by the previous homogeneous J
c model. On top of that, the overall stress level of GdBCO bulk is strongly determined by the magnitude and position of the Lorentz force load, and the stress distribution of inhomogeneous J
c model is mainly concentrated in high J
c regions near top surface, instead of being symmetrically distributed along the z-axis as in homogeneous J
c model. The mechanical response of stainless steel reinforced GdBCO bulk was aslo simulated and analyzed. Finally, the coupling effect between the fracture strength variability caused by defects and cracks and the trapped field in GdBCO bulks with r-z plane J
c inhomogeneity is further studied. This study may provide a relatively realistic mechanical response of HTS bulk during FCM, and a novel design consideration for its mechanical reinforcement.
Self-consistent interaction of linear gravitational and electromagnetic waves in non-magnetized plasma
Authors: Garg Deepen , Dodin I.Y. 
Published: February 2024

Abstract
This paper explores the hybridization of linear metric perturbations with linear electromagnetic (EM) perturbations in non-magnetized plasma for a general background metric. The local wave properties are derived from first principles for inhomogeneous plasma, without assuming any symmetries of the background metric. First, we derive the effective (“oscillation-center”) Hamiltonian that governs the average dynamics of plasma particles in a prescribed quasimonochromatic wave that involves metric perturbations and EM fields simultaneously. Then, using this Hamiltonian, we derive the backreaction of plasma particles on the wave itself and obtain gauge-invariant equations that describe the resulting self-consistent gravito-electromagnetic (GEM) waves in a plasma. The transverse tensor modes of gravitational waves are found to have no interaction with the plasma and the EM modes in the geometrical-optics limit. However, for longitudinal GEM modes with large values of the refraction index, the interplay between gravitational and EM interactions in plasma can have a strong effect. In particular, the dispersion relation of the Jeans mode is significantly affected by electrostatic interactions. As a spin-off, our calculation also provides an alternative resolution of the so-called Jeans swindle.
Primordial black holes in non-canonical scalar field inflation driven by quartic potential in the presence of bump
Authors: Heydari Soma , Karami Kayoomars 
Published: February 2024

Abstract
Here, generation of Primordial Black Holes (PBHs) from quartic potential in the presence
of a tiny bump in non-canonical inflationary model has been inquired. It is demonstrated that, a
viable inflationary era can be driven through the quartic potential in non-canonical framework
with a power-law Lagrangian density. Furthermore, setting a suitable function of inflaton field as
a correction term (like a bump) to the quartic potential, causes the inflaton to slow down for a
while. In such a short time span, the amplitude of the scalar perturbations power spectrum on
small scales grows up sufficiently versus CMB scales. In addition to the bump feature, the
enhancing effect of the α parameter of the Lagrangian on the amplitude of the scalar power
spectrum has been shown. Fine tuning of three parameter Cases of the model results in generating
of three Cases of PBHs. In addition, we investigate the secondary Gravitational Waves (GWs)
produced during generation of PBHs and show that their contemporary density parameter spectra
(ΩGW0
) can be tracked down by GWs detectors.
How many sessions of quantum key distribution are allowed from the first launch to the next restart of the system?
Authors: Molotkov S N 
Published: February 2024

Abstract
Quantum cryptography systems are systems for extending the initial start key, which is required at the start of the system, to ensure information-theoretic authentication of messages in the classical communication channel. In subsequent sessions, a quantum key is generated, part of which is used for authentication in subsequent sessions. There is a fundamental question for quantum cryptography—how many sessions of quantum key distribution (QKD) can be held until the cryptographic properties of the quantum keys are reached a critical level, after which they can no longer be used for cryptographic purposes, and a new restart of the quantum cryptography system will be required. An explicit expression of the allowable number of sessions of quantum key distribution is obtained. It is shown that for the real parameters of the system, it is possible for the system to work almost indefinitely until the next initialization.
The violet laser irradiation influence on the dispersive properties of the PVA/MO composite thick
Authors: Maysam T Sarah , AbdulWahhab Nihal A , Al-Arajiy Addnan H 
Published: February 2024

Abstract
Polyvinyl alcohol (PVA) polymer, methyl orange (MO) and their composite was dissolved in water in order to prepare films with different thickness by casting method. The films were irradiated by a violet laser with a wavelength 405 nm for different times (0, 10, 20, 30 and 40) minute. The dispersion parameters were calculated before and after exposure to the laser using the Wemple–DiDomenico method. Dispersion energy (E
d) and the single oscillator energy of electronic transition (E
o) were increased with increasing the irradiating time for PVA, MO and PVA/MO thick films. This is useful to modify geometrical and optical specifications for materials which has many applications especially in the medical field. The Urbach energy also can be controlled by the irradiation times since it decreased with increasing the laser irradiation time which can be used to enhance the structure of the material.
Orbital angular momentum sensing of composite vortex light in a single-layer graphene system
Authors: Al-Hawary S I S , Altalbawy Farag M A , Rodriguez-Benites C , Kumar A , Kadhum Wesam R , Zaurbekova N , Abbas H A , Shoja S J , Alawadi A , Sivaraman R 
Published: February 2024

Abstract
This paper explores the impact of orbital angular momentum (OAM) in composite vortex light on the absorption and dispersion characteristics of a weak probe light interacting with a single-layer graphene system. Through systematic investigation, we demonstrate the exceptional control achievable over absorption and dispersion profiles by manipulating the OAM of light. Under resonance conditions for the probe light, transparent regions emerge in the spatial profile of probe absorption, and the number of these transparent regions can be precisely regulated by adjusting the OAM number of the composite vortex light. Conversely, in the case of off-resonance probe light, amplified regions surface in the absorption spectrum, with the number of these regions controllable by the OAM state of the composite vortex light. These findings hold significant implications for optical communication systems, offering a valuable tool for the detection and measurement of the OAM number of composite vortex light, and paving the way for advancements in tailored signal processing and communication technologies.
Mapping dynamic spatial patterns of brain function with spatial-wise attention
Authors: Liu Yiheng , Ge Enjie , He Mengshen , Liu Zhengliang , Zhao Shijie , Hu Xintao , Qiang Ning , Zhu Dajiang , Liu Tianming , Ge Bao 
Published: February 2024

Abstract

Objective: Using functional magnetic resonance imaging (fMRI) and deep learning to discover the spatial pattern of brain function, or functional brain networks (FBNs) has been attracted many reseachers. Most existing works focus on static FBNs or dynamic functional connectivity among fixed spatial network nodes, but ignore the potential dynamic/time-varying characteristics of the spatial networks themselves. And most of works based on the assumption of linearity and independence, that oversimplify the relationship between blood-oxygen level dependence signal changes and the heterogeneity of neuronal activity within voxels. Approach: To overcome these problems, we proposed a novel spatial-wise attention (SA) based method called Spatial and Channel-wise Attention Autoencoder (SCAAE) to discover the dynamic FBNs without the assumptions of linearity or independence. The core idea of SCAAE is to apply the SA to generate FBNs directly, relying solely on the spatial information present in fMRI volumes. Specifically, we trained the SCAAE in a self-supervised manner, using the autoencoder to guide the SA to focus on the activation regions. Experimental results show that the SA can generate multiple meaningful FBNs at each fMRI time point, which spatial similarity are close to the FBNs derived by known classical methods, such as independent component analysis. Main results: To validate the generalization of the method, we evaluate the approach on HCP-rest, HCP-task and ADHD-200 dataset. The results demonstrate that SA mechanism can be used to discover time-varying FBNs, and the identified dynamic FBNs over time clearly show the process of time-varying spatial patterns fading in and out. Significance: Thus we provide a novel method to understand human brain better. Code is available at https://github.com/WhatAboutMyStar/SCAAE.
Fork-shaped neural interface with multichannel high spatial selectivity in the peripheral nerve of a rat
Authors: Choi Wonsuk , Park HyungDal , Oh Seonghwan , Hong Jeong-Hyun , Kim Junesun , Yoon Dae Sung , Kim Jinseok 
Published: February 2024

Abstract

Objective. This study aims to develop and validate a sophisticated fork-shaped neural interface (FNI) designed for peripheral nerves, focusing on achieving high spatial resolution, functional selectivity, and improved charge storage capacities. The objective is to create a neurointerface capable of precise neuroanatomical analysis, neural signal recording, and stimulation. Approach. Our approach involves the design and implementation of the FNI, which integrates 32 multichannel working electrodes featuring enhanced charge storage capacities and low impedance. An insertion guide holder is incorporated to refine neuronal selectivity. The study employs meticulous electrode placement, bipolar electrical stimulation, and comprehensive analysis of induced neural responses to verify the FNI’s capabilities. Stability over an eight-week period is a crucial aspect, ensuring the reliability and durability of the neural interface. Main results. The FNI demonstrated remarkable efficacy in neuroanatomical analysis, exhibiting accurate positioning of motor nerves and successfully inducing various movements. Stable impedance values were maintained over the eight-week period, affirming the durability of the FNI. Additionally, the neural interface proved effective in recording sensory signals from different hind limb areas. The advanced charge storage capacities and low impedance contribute to the FNI’s robust performance, establishing its potential for prolonged use. Significance. This research represents a significant advancement in neural interface technology, offering a versatile tool with broad applications in neuroscience and neuroengineering. The FNI’s ability to capture both motor and sensory neural activity positions it as a comprehensive solution for neuroanatomical studies. Moreover, the precise neuromodulation potential of the FNI holds promise for applications in advanced bionic prosthetic control and therapeutic interventions. The study’s findings contribute to the evolving field of neuroengineering, paving the way for enhanced understanding and manipulation of peripheral neural functions.
Formation, propagation and conversion of transport barriers triggered by dynamical critical gradient in tokamak plasmas
Authors: Li Xiaobo , Guo Zhibin , Diamond Patrick H. 
Published: February 2024

Abstract
In this work, we propose a reduced model with a dynamical critical gradient to study the formation, propagation, and conversion of the transport barriers. In contrast to the commonly adopted static critical gradient, an evolving critical gradient self-consistently softens the profile stiffness, so as to facilitate the generation of transport barriers. This is especially crucial to the internal transport barrier (ITB) formation. Numerically, we show that the inhomogeneity of turbulent and neoclassical diffusivities can induce the global wave front propagation of the transport barrier. When the heating power ramps quickly, the ITB propagates unidirectionally to the edge region and converts into an edge transport barrier. For slow power ramping, the propagating ITB will bifurcate into bidirectional wavefronts and finally convert into a steady double transport barrier state. Our model uncovers the vital role of a dynamical ‘profile-stiffness’ in depicting the global dynamics of the transport barrier.
Observation of fast electron redistribution during saturated kink mode in high

β

p

H-mode discharge with central heating in EAST tokamak
Authors: Xu Liqing , Lin Shiyao , Mai Chaowei , Chao Yan , Zhou Tianfu , Wang Wei , Huang Yueheng , Jia Tianqi , Chu Yuqi , Wang Yifeng , Duan Yanmin , Liu Jianwen ,   the EAST Team
Published: February 2024

Abstract
In the EAST tokamak, we have developed an internal transport barrier (ITB) high-confinement mode (H-mode) scenario characterized by dominant electron heating and centrally peaked electron temperature profiles, facilitated primarily through the combustion of lower hybrid current drive and electron cyclotron radio heating (ECRH). Hard x-ray diagnostics reveal a marked increase in the population of fast electrons with energy from 30 keV to 80 keV, concurrent with augmented ECRH power during H-mode plasma operations. This surge in fast electron population precedes the formation of the electron temperature ITB (Te-ITB). Within the Te-ITB H-mode discharge, a mild and long-lived m/n = 1/1 mode (where m and n denote the toroidal and poloidal mode numbers, respectively) emerges proximal to the ITB region. This mode precipitates a redistribution of fast electrons, contributing to an increase in the safety factor near the magnetic axis and thereby promoting the stability of the Te-ITB. Furthermore, we explore the influence of fast electrons on plasma pressure and examine the effects of the profile of fast electrons on the central Te. Strategies to maintain the m/n = 1/1 mode at a moderate amplitude are also discussed, highlighting their significance in the sustained management of Te-ITB.