bluuebunny/crossref_metadata_2025 huggingface dataset:
Host-encoded CTCF regulates human cytomegalovirus latency via chromatin looping
Authors: Groves Ian J. , Matthews Stephen M. , O’Connor Christine M.
Published: February 2024

Human cytomegalovirus (HCMV) is a prevalent pathogen that establishes life-long latent infection in hematopoietic cells. While this infection is usually asymptomatic, immune dysregulation leads to viral reactivation, which can cause significant morbidity and mortality. However, the mechanisms underpinning reactivation remain incompletely understood. The HCMV major immediate early promoter (MIEP)/enhancer is a key factor in this process, as its transactivation from a repressed to active state helps drive viral gene transcription necessary for reactivation from latency. Numerous host transcription factors bind the MIE locus and recruit repressive chromatin modifiers, thus impeding virus reactivation. One such factor is CCCTC-binding protein (CTCF), a highly conserved host zinc finger protein that mediates chromatin conformation and nuclear architecture. However, the mechanisms by which CTCF contributes to HCMV latency were previously unexplored. Here, we confirm that CTCF binds two convergent sites within the MIE locus during latency in primary CD14
+
monocytes, and following cellular differentiation, CTCF association is lost as the virus reactivates. While mutation of the MIE enhancer CTCF binding site does not impact viral lytic growth in fibroblasts, this mutant virus fails to maintain latency in myeloid cells. Furthermore, we show the two convergent CTCF binding sites allow looping to occur across the MIEP, supporting transcriptional repression during latency. Indeed, looping between the two sites diminishes during virus reactivation, concurrent with activation of MIE transcription. Taken together, our data reveal that three-dimensional chromatin looping aids in the regulation of HCMV latency and provides insight into promoter/enhancer regulation that may prove broadly applicable across biological systems.
Human transferrin receptor can mediate SARS-CoV-2 infection
Authors: Liao Zhiyi , Wang Chaoming , Tang Xiaopeng , Yang Mengli , Duan Zilei , Liu Lei , Lu Shuaiyao , Ma Lei , Cheng Ruomei , Wang Gan , Liu Hongqi , Yang Shuo , Xu Jingwen , Tadese Dawit Adisu , Mwangi James , Kamau Peter Muiruri , Zhang Zhiye , Yang Lian , Liao Guoyang , Zhao Xudong , Peng Xiaozhong , Lai Ren
Published: February 2024

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been detected in almost all organs of coronavirus disease-19 patients, although some organs do not express angiotensin-converting enzyme-2 (ACE2), a known receptor of SARS-CoV-2, implying the presence of alternative receptors and/or co-receptors. Here, we show that the ubiquitously distributed human transferrin receptor (TfR), which binds to diferric transferrin to traffic between membrane and endosome for the iron delivery cycle, can ACE2-independently mediate SARS-CoV-2 infection. Human, not mouse TfR, interacts with Spike protein with a high affinity (K
D
~2.95 nM) to mediate SARS-CoV-2 endocytosis. TfR knock-down (TfR-deficiency is lethal) and overexpression inhibit and promote SARS-CoV-2 infection, respectively. Humanized TfR expression enables SARS-CoV-2 infection in baby hamster kidney cells and C57 mice, which are known to be insusceptible to the virus infection. Soluble TfR, Tf, designed peptides blocking TfR-Spike interaction and anti-TfR antibody show significant anti-COVID-19 effects in cell and monkey models. Collectively, this report indicates that TfR is a receptor/co-receptor of SARS-CoV-2 mediating SARS-CoV-2 entry and infectivity by likely using the TfR trafficking pathway.
A universal and scalable transformation of bulk metals into single-atom catalysts in ionic liquids
Authors: Wang Shujuan , Lu Minghui , Xia Xuewen , Wang Fei , Xiong Xiaolu , Ding Kai , Pang Zhongya , Li Guangshi , Xu Qian , Hsu Hsien-Yi , Hu Shen , Ji Li , Zhao Yufeng , Wang Jing , Zou Xingli , Lu Xionggang
Published: February 2024

Single-atom catalysts (SACs) with maximized metal atom utilization and intriguing properties are of utmost importance for energy conversion and catalysis science. However, the lack of a straightforward and scalable synthesis strategy of SACs on diverse support materials remains the bottleneck for their large-scale industrial applications. Herein, we report a general approach to directly transform bulk metals into single atoms through the precise control of the electrodissolution–electrodeposition kinetics in ionic liquids and demonstrate the successful applicability of up to twenty different monometallic SACs and one multimetallic SAC with five distinct elements. As a case study, the atomically dispersed Pt was electrodeposited onto Ni
3
N/Ni-Co-graphene oxide heterostructures in varied scales (up to 5 cm × 5 cm) as bifunctional catalysts with the electronic metal–support interaction, which exhibits low overpotentials at 10 mA cm
−2
for hydrogen evolution reaction (HER, 30 mV) and oxygen evolution reaction (OER, 263 mV) with a relatively low Pt loading (0.98 wt%). This work provides a simple and practical route for large-scale synthesis of various SACs with favorable catalytic properties on diversified supports using alternative ionic liquids and inspires the methodology on precise synthesis of multimetallic single-atom materials with tunable compositions.
Opportunities of Advanced Physical Studies at the Hefei Advanced Light Facility
Authors: Sun 孙 Zhe 喆 , Feng 封 Donglai 东来
Published: February 2024

Synchrotron radiation has transformed the role of x-rays as a mainstream tool for probing the atomic and electronic structure of materials. Synchrotron-based x-ray sciences have been widely used to study the microscopic structure, electronic states, chemical composition, and other properties of materials in fields such as quantum materials, soft matter, energy storage, catalysis, biology, and electronics.
Revisiting loop quantum gravity with selfdual variables: classical theory
Authors: Sahlmann Hanno , Seeger Robert
Published: February 2024

We review the classical formulation of general relativity as an

S
L

(
2
,

C

)

gauge theory in terms of Ashtekar’s self-dual variables and reality conditions for the spatial metric (first reality condition) and its evolution (second reality condition), and we add some new observations and results. We first explain in detail how a connection taking values in the Lie algebra of the complex Lorentz group yields two spin(3,1) connections, one self-dual and one anti-self-dual, without the need for a spin structure. We then demonstrate that the self-dual part of the complexified Palatini action in Ashtekar variables requires a holomorphic phase space description in order to obtain a non-degenerate symplectic structure. The holomorphic phase space does not allow for the implementation of the reality conditions as additional constraints, so they have to be taken care of ‘by hand’ during the quantisation. We also observe that, due to the action being complex, there is an overall complex phase that can be chosen at will. We then review the canonical formulation and the consequences of the implementation of the reality conditions. We pay close attention to the transformation behaviour of the various fields under (complex) basis changes, as well as to complex analytic properties of the relevant functions on phase space.
Electrostatic potential of a uniformly charged annulus
Authors: Ciftja Orion , Bentley Jr Cleo L
Published: February 2024

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Calculating Global Minimum Points to Binary Polynomial Optimization Problem: Optimizing the Optimal PMU Localization Problem as a Case-Study
Authors: Theodorakatos Nikolaos P. , Moschoudis Angelos P. , Babu Rohit
Published: February 2024

State estimation (SE) is an algorithmic function of an energy management system (EMS). SE provides an actual-time monitoring and control of modern electrical power grids. State Estimation can be worked with sufficiency using Phasor Measurement Units optimally placed within a power grid. This paper concerns the implementation of proper algorithms embedded in optimization solvers to the optimal PMU localization problem solving globally. The optimization model is formulated as a 0 - 1 nonlinear minimization problem. The problem is transformed to a polyhedron using linearization methods and B&B tree. In this model, we use a linear cost function under polynomial constraints and binary restrictions on the design variables in a symbolic format. This mathematical model is programmed in the YALMIP environment which is fully compatible with MATLAB. The 0 - 1 Nonlinear Programming (NLP) model is suitable for getting concisely global optimal solutions. The optimal solution is given by a wrapped optimization engine including a local optimizer routine performing together with a mixed-Integer-Linear Programming routine. The solution is achieved within a zero-gap precisely encountered during the iterative process. This tolerance criterion is a necessity for a successful implementation of the B&B tree because it ensures global optimality with an acceptance relative gap. The minimization model is implemented in a YALMIP code fully compatible with MATLAB in two stages. Initially, an objective function with one term is minimized to discover a number of sensors for wide-area monitoring, control and state estimator applications. Then, an extra product is considered in the objective to suffice maximum reliability for observing the network buses. The numerical minimization models are applied to standard power networks in the direction to be solved globally.
An Incomplete Observability-Constrained PMU Allocation Problem by Using Mathematical and Evolutionary Algorithms
Authors: Theodorakatos Nikolaos P. , Babu Rohit , Moschoudis Angelos P.
Published: February 2024

The purpose of this paper is to introduce several optimization algorithms that can be used to address optimization models in the power network, where the level of observability may be either complete or incomplete. These algorithms include discrete, continuous and metaheuristic methods. Initially, the optimization problem is approached by implementing a zero-one mixed integer linear program solved by several methods, including branch and bound revised simplex and primal dual-simplex in combination with interior point algorithms. To solve the problem of depth-one-unobservability (DoOU), a nonlinear program is proposed using Sequential Quadratic Programming (SQP), Interior-Point methods (IPMs) or YALMIP\s branch-and-bound algorithm. Additionally, the paper proposes the use of metaheuristic algorithms, such as Genetic Algorithms (GAs) and Binary Particle Swarm Optimization (BPSO), to solve optimization problems under incomplete observability. The proposed algorithms are tested using simulations on IEEE standard systems to illustrate their efficiency and reliability in solving the optimization problem under partial observability. Overall, the paper concludes that these algorithms can efficiently lead to the optimum point in a reasonable runtime. Hence, this work examines the problem of putting a restricted PMUs number to make the DoOU and to give a feedback to the state estimation routine accuracy.
Geogebra in the visualization of integrating factors in non-exact differential equations
Authors: Olivares Jorge , Martin P. , Valero E.
Published: February 2024

In the present work, integrating factors used in the solution of non-exact differential equations will be shown with general examples through software application of dynamic geometry GeoGebra. Now these applets are part of theteaching support material in the eigineering careers of the University of Antofagasta on 2020.
Subdiffusive dynamics and hydrodynamic fluctuations: how the latter affect the former.
Authors: Bakalis Evangelos , Zerbetto Francesco
Published: February 2024

The characteristics of subdiffusion are influenced by hydrodynamic fluctuations, not the scaling of the mean square displacement (MSD) at the long time limit, but rather the transition of this property from ballistic behaviour at early times to its final scaling at large times. Additionally, since a significant portion of the normalised velocity autocorrelation function (NVAF), a widely used motion descriptor, no longer adequately describes the antipersistent character that is typical of a subdiffusive motion, it is also impacted by these fluctuations. The combined findings can lead to misleading conclusions if hydrodynamic fluctuations are not taken into account. Diffusing and vorticity time scales are crucial for the way the motion turns into the final subdiffusion dynamics, whose exponent is determined by the scaling of the friction.
Statistical moments for simulation calibration with model-bridge
Authors: Batalo B , Souza LS , Yamazaki K
Published: February 2024

Computer simulations are actively used for analyzing complex phenomena, especially in fields where access to their real-world counterparts is not feasible, such as physics, chemistry, material science, and others. The key to executing successful simulations is making sure that the parameters of a simulator reflect real-world scenarios, a tedious and error-prone effort addressed through simulation calibration. Recently, several methods have been proposed to automatize this task by learning from previously calibrated simulations using a model-bridge paradigm: a complex simulation is replaced by a simpler surrogate model, which can then be bridged to the calibrated simulation parameters. However, designing the surrogate model is a non-trivial problem involving trade-offs between simplicity of representation, interpretability and calibration accuracy, as well as the complexity of the bridge model required to map the surrogate to calibrated parameters. Further, while effective, such approaches can be non-intuitive for practitioners due to their distance from the simulation. In this paper, we view a simulation as a distribution of output variables, which can be easily represented by statistical moments. This yields a very simple and interpretable surrogate that can be bridged to calibrated parameters with a simple linear regression. We show that our method outperforms previous approaches, in terms of calibration accuracy and time, through experiments on simulations of turbulent flow dynamics and synthetic signals.
LES analysis of local isotropic turbulence depending on the spatial scale of the external forcing field
Authors: Minami Koki , Suzuki Hiroki , Kouchi Toshinori
Published: February 2024

The study investigates the effect of the parameterisation of an external force scheme based on trigonometric functions on turbulence. In particular, the dependence of the generated turbulence on the Reynolds number and the influence of its spatial parameters are investigated. The turbulence used is generated by a large-eddy simulation based on a high-precision finite volume method, and the turbulence energy and isotropy of the turbulence are also investigated. The parameter of the external force field used in this study characterises the wavelength of the trigonometric function, and the influence of this parameter on the spatial scale is studied in detail. As a result, steady turbulent fields are generated and isotropic turbulence is observed at different spatial scales of the external force field with M=2, 3 and 4. The property of increasing turbulence energy with increasing Reynolds number is confirmed.
Computer Simulation of Explosive Emission Processes in Strong Electromagnetic Fields
Authors: Galstyan E.A. , Kudryashova T.A. , Polyakov S.V. , Tarasov N.I.
Published: February 2024

The paper discusses the problem of computer simulation of explosive emission processes in strong electromagnetic fields. In this work, a numerical method for calculating electron emission from the surface of a metal cathode for the axial symmetric geometry of a technical system is proposed. For modelling, the particle method and grid calculations of electromagnetic fields based on Maxwell’s equations are applied. The approach uses the representation of large smoothed Gaussian particles and implements calculations of the electromagnetic fields on Cartesian spatial grids. The software realization is directed towards on parallel computing. The calculation of the emission process in a coaxial cylindrical diode with magnetic self-insulation with the use of developed technique was carried out. The process is considered for two situations: with and without the longitudinal plasma layer. The calculations show that the presence of plasma leads to an increase in the emission current. This result is consistent with the results of experiments.
Modeling of the Influence of Oxidation on the Energy of Interfacial Exchange Interaction in Co/CoO Films
Authors: Brykin L. O. , Afremov L. L.
Published: February 2024

The interphase exchange interaction energy of ferromagnetic/antiferromagnetic films is determined through the mean spin theory. The thickness of the oxidized layer affects the exchange field, as shown by the Co/CoO film.
Linear stability of viscoplastic flows down an incline
Authors: Calusi Benedetta , Farina Angiolo , Fusi Lorenzo , Iulian Palade Liviu , Rosso Fabio
Published: February 2024

The stability analysis of viscoplastic flows down an inclined plane is done by comparing results obtained through theoretical and numerical studies of “regularized” models. The theoretical analysis is performed for Regularized Bingham and Casson-like fluids via the long-wave approximation method. In particular, the Bingham and the Casson flow have different stability characteristics, for Bingham-type materials an increase in yield stress leads to flow destabilization, while Casson-type materials show the opposite behaviour. The numerical study is performed by using the Papanastasiou and the “exact” Bingham model via a spectral method. The comparison between theoretical and numerical results shows excellent agreement. Our findings highlight that “regularized” and “exact” flow and can have stability characteristics, although they are “practically indistinguishable”. We validate our approach with the Regularized Bingham-like model, which is in rather satisfactory agreement with the experimental data.
Theoretical modeling of the electronic structure and Fermi surfaces of Gd4Sb3 and GdSb2 compounds
Authors: Baidak S T , Lukoyanov A V
Published: February 2024

Our theoretical modeling of the electronic structure in the intermetallic Gd4Sb3 and GdSb2 compounds has been done in the framework of density functional theory accounting for spin-orbit coupling. It revealed the metallic character of the summed total density of electronic states for both materials. The complicated Fermi surfaces were found in the half-metallic Gd4Sb3 compound which corresponds to the band structure. The GdSb2 material is obtained to be a bad metal with the low density of states near the Fermi energy, the Fermi surfaces of GdSb2 are found to have the cylindrical shape.
How Fast Do Distribution and Semantics of Polysemic Words Change?
Authors: Bochkarev Vladimir V. , Shevlyakova Anna V.
Published: February 2024

Creation of large diachronic text corpora triggered studies of evolution of natural languages using quantitative methods in the last decade. For the first time, it became possible to raise questions about general patterns of lexical semantic change. In the work by W. Hamilton et al., 2016, a hypothesis was formulated about a more rapid change in the meanings of polysemic words. In this paper, we consider how frequency of words influence variations of semantic metrics. We use explicit word vector representations and Jensen-Shannon divergence as a measure of change in the distribution and semantics of a word. The obtained results show that changes in the frequency ratio of a word in different meanings can themselves lead to a change in a word distribution, even in the absence of any changes in its meaning. Therefore, the observations made in the work by W. Hamilton et al about correlation between the rate of change of words and their local cluster coefficient in the semantic connection network (considered as a quantitative measure of polysemy) can be fully explained by the effect described in the article.
Passive damping of vibrations of prestressed thin-walled structures using piezoelectric elements connected to electric circuits
Authors: Lekomtsev Sergey V , Matveenko Valerii P , Senin Alexander N
Published: February 2024

In this paper we estimate the influence of static pressure on the efficiency of passive damping of vibrations of a circular cylindrical shell using an open piezoelectric ring connected to a passive electric circuit of different configurations. The mathematical formulation of the problem of the dynamic behavior of an electroelastic structure is based on the variational principle of virtual displacements, which is written in matrix form taking into account the prestressed non-deformed state caused by applied loads, and as well as the work done by external surface forces, inertial forces and external electric field to transfer the free charge. The resulting equation is supplemented by the equation for the electric circuit, which relates the voltage at the piezoelectric ring with the corresponding electric charge. The problem is solved in the framework of 3D formulation using the finite element method. As examples, we consider the serial RL- and resistive R-circuits. Their parameters providing the most effective damping of free vibrations in terms of their decay rate are determined by solving the optimization problem. The results obtained by numerical simulations are compared with the results calculated by the analytical formulas at different values of static pressure.
Predictive analysis in industry
Authors: Echkina Eugenia , Levichev Alexander , Sushko Andrey
Published: February 2024

Predictive analytics is a field of knowledge that allows you to make informed decisions, prepare for unforeseen situations and anticipate all kinds of emergencies. Recently, predictive analysis has been actively used in industry: based on historical data, the model makes a probabilistic forecast of the device’s behavior in the near future. This paper provides a comparative analysis of two predictive models, which both could self-learn and had the property of self-correction. The accuracy of predicting the development of a defect in industrial equipment, as well as the prediction horizon, were evaluated. Particular attention is paid to the peculiarity of working with data obtained from production sensors.
Application of higher-order FV-WENO scheme to the interaction between shock wave and bubble
Authors: Yu J , Hao Y , Sheng Z X , Zhang X P , Chen J P , Zhang J , Yang J
Published: February 2024

The high-order finite volume-WENO (Weighted Essentially Non-Oscillatory) scheme combines the finite volume method with the WENO method, allowing for high-order accuracy and accurate simulation of complex physical phenomena. It has advantages in handling shock waves and bubble interactions. The idea of this method is to discretize the physical equations into a set of conservation equations and use the WENO method to calculate the numerical fluxes on each finite volume cell. This approach is effective in dealing with problems such as shock wave propagation, bubble deformation, and evolution. In fluid dynamics simulation and research, the high-order FV-WENO scheme has significant application prospects. It can provide accurate numerical solutions and simulate complex physical phenomena, making it widely applicable in scientific research and engineering. In this study, we simulated the interactions between shock waves and single or double bubbles, obtaining the complete process of bubble collapse with clear bubble interfaces and strong program stability.
Asymptotic behaviour for a parabolic p-Laplacian equation with an advection force
Authors: Aal-Rkhais Habeeb A. , Qasim Ruba H.
Published: February 2024

The rescaling method is presented to allow us establishing the interface functions and the nonnegative local solutions to the evolution of nonlinear degenerate parabolic p-Laplacian process with conservation laws that are posed in one-dimensional space. This equation has a self-similar solution which represents the main feature of this work. The Cauchy problem (CP) for this equation with specific restrictions in the range of parameters and the negative advection coefficient is considered. In this work, there are several regions to discuss the qualitative analysis for the local weak solutions and the asymptotic interfaces in the irregular domains. The dominating of the advection force over the p-Laplacian type diffusion will appear clearly in these regions. Moreover, the solutions of the CP for the degenerate parabolic p-Laplacian advection equations are asymptotically equal to the solutions of advection equations under some restrictions.