bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heisenberg spins on an anisotropic triangular lattice: PdCrO2 under uniaxial stress
Authors: Sun Dan , Sokolov Dmitry A , Waite Richard , Khim Seunghyun , Manuel Pascal , Orlandi Fabio , Khalyavin Dmitry D , Mackenzie Andrew P , Hicks Clifford W 
Published: December 2021

Abstract
When Heisenberg spins interact antiferromagnetically on a triangular lattice and nearest-neighbor interactions dominate, the ground state is 120° antiferromagnetism. In this work, we probe the response of this state to lifting the triangular symmetry, through investigation of the triangular antiferromagnet PdCrO2 under uniaxial stress by neutron diffraction and resistivity measurements. The periodicity of the magnetic order is found to change rapidly with applied stress; the rate of change indicates that the magnetic anisotropy is roughly forty times the stress-induced bond length anisotropy. At low stress, the incommensuration period becomes extremely long, on the order of 1000 lattice spacings; no locking of the magnetism to commensurate periodicity is detected. Separately, the magnetic structure is found to undergo a first-order transition at a compressive stress of ∼0.4 GPa, at which the interlayer ordering switches from a double-to a single-q structure.
Distribution of first-reaction times with target regions on boundaries of shell-like domains
Authors: Grebenkov Denis S , Metzler Ralf , Oshanin Gleb 
Published: December 2021

Abstract
We study the probability density function (PDF) of the first-reaction times between a diffusive ligand and a membrane-bound, immobile imperfect target region in a restricted ‘onion-shell’ geometry bounded by two nested membranes of arbitrary shapes. For such a setting, encountered in diverse molecular signal transduction pathways or in the narrow escape problem with additional steric constraints, we derive an exact spectral form of the PDF, as well as present its approximate form calculated by help of the so-called self-consistent approximation. For a particular case when the nested domains are concentric spheres, we get a fully explicit form of the approximated PDF, assess the accuracy of this approximation, and discuss various facets of the obtained distributions. Our results can be straightforwardly applied to describe the PDF of the terminal reaction event in multi-stage signal transduction processes.
Review on Higgs hidden-dark sector physics
Authors: Lagouri Theodota 
Published: December 2021

Abstract
The Standard Model (SM), while extremely powerful as a description of the strong, electromagnetic and weak interactions, does not provide a natural candidate to explain Dark Matter (DM). Theoretical as well as experimental motivation exists for the existence of a hidden or dark sector of phenomena that couples either weakly or in a special way to SM fields. Hidden sector or dark sector states appear in many extensions to SM to provide a particular candidate DM in the universe or to explain astrophysical observations. If there is such a family of Beyond the Standard Model (BSM) particles and interactions, they may be accessible experimentally at the Large Hadron Collider (LHC) at CERN and at future High Energy Colliders. In this paper, the main focus is given on selected searches conducted at LHC experiments related to Higgs Hidden-Dark Sector Physics. The current constraints and future prospects of these studies are summarized.
Minimizing IL-6 and IL-10 signalling pathway elements using lumping species and parameters
Authors: Rasool Hemn M , Khoshnaw Sarbaz H A 
Published: December 2021

Abstract
There are many cell signalling pathways that include a higher set of elements. Understanding the dynamics of such systems becomes a difficult issue in systems biology. Mathematical approaches with computational simulations provide a wide range to simplify such complex models and to predicate their dynamics. A powerful technique for reducing the complexity of cell signalling pathways is lumping variables and parameters. In this work, we suggest this technique to reduce the number of elements of IL-6 and IL-10 signalling pathways. The reduced model given in this work provides one a better understanding and predicting some model dynamics, and gives accurate approximate solutions. Computational results show that there is a good agreement between the model dynamics for the original and the simplified models.
Pseudo-bounces vs. new instantons
Authors: Espinosa J.R. , Huertas J. 
Published: December 2021

Abstract
Some false vacua do not decay via bounces. This usually happens when a flat direction of the tunneling action due to scale invariance is lifted to a sloping valley by a scale breaking perturbation, pushing the bounce off to infinity. We compare two types of alternative decay configurations that have been proposed recently to describe decay in such cases: pseudo-bounces and new instantons. Although both field configurations are quite similar, we find that the pseudo-bounce action is lower than the new instanton one and describes more faithfully the bottom of the action valley. In addition, pseudo-bounces cover a range of field space wider than new instantons
and, as a result, lead to a decay rate that can be lower than the one via new instantons by orders of magnitude.
Dynamical attractors in contracting spacetimes dominated by kinetically coupled scalar fields
Authors: Ijjas Anna , Pretorius Frans , Steinhardt Paul J. , Garfinkle David 
Published: December 2021

Abstract
We present non-perturbative numerical relativity simulations
of slowly contracting spacetimes in which the scalar field driving
slow contraction is coupled to a second scalar field through an
exponential non-linear σ model-type kinetic interaction.
These models are important because they can generate a nearly
scale-invariant spectrum of super-Hubble density fluctuations fully
consistent with cosmic microwave background observations. We show
that the non-linear evolution rapidly approaches a homogeneous,
isotropic and flat Friedmann-Robertson-Walker (FRW) geometry for a
wide range of inhomogeneous and anisotropic initial conditions.
Ultimately, we find, the kinetic coupling causes the evolution to
deflect away from flat FRW and towards a novel Kasner-like
stationary point, but in general this occurs on time scales that are
too long to be observationally relevant.
Current drive experiments in SST1 tokamak with lower hybrid waves
Authors: Sharma P.K. , Raju D. , Pathak S.K. , Srinivasan R. , Ambulkar K.K. , Parmar P.R. , Virani C.G. , Kumar J. , Sharma S. , Singh C. , Thakur A.L. , Tanna V.L. , Prasad U. , Khan Z. , Raval D.C. , Gupta C.N. , Krishnan B. , Nair S. , Sharma D.K. , Doshi B. , Vasani M. , Mahajan K. , Rajpal R. , Manchanda R. , Asudani K. , Gupta M.K. , Chowdhuri M.B. , Tanna R.L. , SST-1  , Diagnostic Teams  
Published: December 2021

Abstract
The steadystate superconducting tokamak (SST1) is aimed to demonstrate long pulse plasma discharges employing non-inductive current drive by means of lower hybrid current drive (LHCD) system. The major and minor radius of the machine is 1.1 m and 0.2 m, respectively. The LHCD system for SST1 comprises of klystrons, each rated for 0.5 MW-CW rf power at a frequency of 3.7 GHz. The grill antenna comprises of two rows, each row accommodating 32 waveguide elements. Electron cyclotron resonance breakdown assisted Ohmic plasma is formed in SST1 to overcome the issues associated with low loop voltage start-ups. With recent modifications in the poloidal coils configuration, even with narrow EC pulse (∼50 ms), good repeatable and consistent Ohmic plasmas could be produced which helped in carrying out LHCD current drive experiments on SST1. These experiments demonstrated both fully as well as partially driven non-inductive plasma current in SST1 tokamak. Discharges with zero loop voltages were obtained. The interaction of lower hybrid waves with plasma and generation of suprathermal electrons could be established using energy spectra measured by CdTe detectors. Various other signatures like drop in loop voltages, negative loop voltages, spikes in hard x-rays and increase in second harmonic ECE signal, further confirmed the current drive by LHW’s. The beneficial effect of LHW’s in suppressing hard x-rays was also demonstrated in these experiments. The longest discharge of ∼650 ms could be obtained in SST1 with the help of LHW’s. In this paper, the experimental results obtained with LHCD experiments on SST1 is reported and discussed in more details.
International Conference «Marchuk Scientific Readings 2021» (MSR-2021)
Authors: Mikhailov G A , Kabanikhin S I , Laevsky Yu M , Penenko V V , Glinsky B M , Zagorulko Y A , Shishlenin M A , Podkolodnyy N L , Penenko A V 
Published: December 2021

Abstract
Preface
These Conference Proceedings contain the selected papers of the International Conference «Marchuk Scientific Readings 2021» (MSR-2021) held on October 4 - 8, 2021, in Akademgorodok, Novosibirsk, Russia.
The purpose of the «Marchuk Scientific Readings» conference series is to gather specialists in numerical analysis, applied mathematics, mathematical modeling, computational technologies, information systems, artificial intelligence, and machine learning to discuss, identify and systematize current results, applications, and promising directions in computational mathematics and computer science.
Due to the risk of spreading coronavirus infection, the meeting took place virtually. The organizers were located in the Institute of Computational Mathematics and Mathematical Geophysics SB RAS (Novosibirsk, Russia). Morning sessions were devoted to the conference sections’ invited oral (20 minutes) and oral (15 minutes) presentations. The Plenary talks (30 minutes) were delivered on the afternoon sessions. Within the timeframe of a talk, there was a possibility to ask and answer several questions from the audience. Technologically, the meeting was carried out on the Zoom platform. Plenary talks were broadcast on youtube.com. This conference was the second one carried out with the help of the Zoom platform, and most of the technical issues were already solved in the previous year. In pandemic conditions, the virtual conference seems to be the most appropriate format to share the research results without exposing the community to the risk of infection.
List of Program committee is available in this pdf.
Approximate methods for solving amplitude-phase problem for discrete signals
Authors: Boikov I V , Zelina Ya V , Vasyunin D I 
Published: December 2021

Abstract
Methods for solving amplitude and phase problems for one and two-dimensional discrete signals are proposed. Methods are based on using nonlinear singular integral equations. In the one-dimensional case amplitude and phase problems are modeled by corresponding linear and nonlinear singular integral equations. In the two-dimensional case amplitude and phase problems are modeled by corresponding linear and nonlinear bisingular integral equations. Several approaches are presented for modeling two-dimensional problems: 1) reduction of amplitude and phase problems to systems of linear and nonlinear singular integral equations; 2) using methods of the theory of functions of many complex variables, problems are reduced to linear and nonlinear bisingular integral equations. To solve the constructed nonlinear singular integral equations, methods of collocation and mechanical quadrature are used. These methods lead to systems of nonlinear algebraic equations, which are solved by the continuous method for solution of nonlinear operator equations. The choice of this method is due to the fact that it is stable against perturbations of coefficients in the right-hand side of the system of equations. In addition, the method is realizable even in cases where the Frechet and Gateaux derivatives degenerate at a finite number of steps in the iterative process. Some model examples have shown effectiveness of proposed methods and numerical algorithms.
On the minimal residual methods for solving diffusion-convection SLAEs
Authors: Il’in V P , Kozlov D I , Petukhov A V 
Published: December 2021

Abstract
The objective of this research is to develop and to study iterative methods in the Krylov subspaces for solving systems of linear algebraic equations (SLAEs) with non-symmetric sparse matrices of high orders arising in the approximation of multi-dimensional boundary value problems on the unstructured grids. These methods are also relevant in many applications, including diffusion-convection equations. The considered algorithms are based on constructing ATA — orthogonal direction vectors calculated using short recursions and providing global minimization of a residual at each iteration. Methods based on the Lanczos orthogonalization, AT — preconditioned conjugate residuals algorithm, as well as the left Gauss transform for the original SLAEs are implemented. In addition, the efficiency of these iterative processes is investigated when solving algebraic preconditioned systems using an approximate factorization of the original matrix in the Eisenstat modification. The results of a set of computational experiments for various grids and values of convective coefficients are presented, which demonstrate a sufficiently high efficiency of the approaches under consideration.
Simulation of heat transfer with considering permafrost thawing in 3D media
Authors: Karavaev D A , Laevsky Y M 
Published: December 2021

Abstract
An approach to mathematical modeling of heat transfer with a permafrost algorithm in 3D media based on the idea of localizing the phase transition area is considered. The paper presents a problem statement for a non-stationary heat transfer and a description of a numerical method based on a predictor-corrector scheme. For a better understanding of the proposed splitting method, the accuracy order of approximation considering inhomogeneous right-hand side was studied. The phase changes in the numerical implementation of permafrost thawing is considered in the temperature range and requires recalculation of coefficients values of the heat equation at each iteration step with respect to time. A brief description of the parallel algorithm based on a 3D decomposition method and the parallel sweep method is presented. A study of the parallel algorithm implementations using a high-performance computing system of the Siberian Supercomputer Center of the SB RAS was performed. The results of the permafrost algorithm on models with wellbores are also presented.
Identification of argumentative sentences in Russian scientific and popular science texts
Authors: Salomatina N V , Pimenov I S , Sidorova E A 
Published: December 2021

Abstract
In this study we analyze the applicability of specific machine learning algorithms to the task of detecting sentences containing argumentation in Russian text. We employ a collection of scientific and popular science texts with manually annotated argumentation to evaluate the quality of identifying argumentative sentences in terms of precision, recall, and F-measure. The experiment involves three algorithms: MNB, SVM, and MLP. The bag of words model is used for representing texts. Lemmas of words in analyzed sentences serve as features for the classification. We perform the automatic selection of informative features in accordance with Variance and χ2 criteria combined with the weight-based filtration of lemmas (via TF*IDF and EMI). The training set includes around 800 sentences, while the test set contains 180. The MNB algorithm demonstrates the highest F-measure and recall scores on almost all feature sets (maximal values reached equal 68.7% and 89% respectively), while the MLP algorithm shows the best precision for about half of feature selection variations (the maximal value is 72.5%).
Mutation hotspots of SARS-CoV-2 RNA motifs conserved in betacoronaviruses
Authors: Kobalo N S , Kulikov A A , Titov I I 
Published: December 2021

Abstract
The pandemic of the coronavirus infection COVID-19, which began at the end of 2019 and caused by the SARS-CoV-2 virus, has led to unprecedented consequences in the world. By the end of May 2021, in the world there were 167 million infected and 3.5 million died directly from infection [1]. SARS-CoV-2 is a beta coronavirus, so it shares many conserved fragments with other known viruses of this type [2]. Since the beginning of the spread of the COVID-19, one of the important issues of research of the SARS-CoV-2 virus has been the search for its conserved RNA motifs and their functional annotation. These motifs are potential targets for the treatment and diagnosis of a disease caused by the virus. This report examines the structural RNA fragments of SARS-CoV-2, similar to the corresponding fragments in other beta coronaviruses [2]. For these RNA motifs the nucleotide variability during the spread of the virus, depending on their secondary structure, was investigated. All the motifs display the similar background variability although contain hypervariable positions.
Determination of the variable density of the rod from natural frequencies of longitudinal vibrations
Authors: Utyashev I M 
Published: December 2021

Abstract
Rods of various configurations are elements of many structures and machines. Therefore, the acoustic and vibration diagnostics of such parts has been widely developed. The paper considers the problem of determining the variable density of the rod from the natural frequencies of longitudinal vibrations. It is assumed that the density changes along the axis and is described by a polynomial function. This approach allows one to determine the law of density variation from a finite set of eigenvalues. The results of the study can find applications for finding hidden defects in steel and composite rods, which arise during the production process or due to corrosion.
Application of regression in algorithm of nonlinear stochastic adaptation of unstable multidimensional objects
Authors: Kolesnikova S I 
Published: December 2021

Abstract
The results of a study of applicability of kernel estimation in the synergetic control systems for the objects unstable in an open-loop state (without a stabilizing control) have been presented. The effectiveness of kernel estimates has been shown for four nonlinear objects with unstable limiting states. The estimate the effectiveness of embedding the kernel predictive estimate of the state variables of a nonlinear object, subjected to disturbances of an unknown nature, into the system of synergetic control is demonstrated.
Using the inverse distribution function method and the modified superposition method in the NMPUD computer system
Authors: Cherkashin D A , Voytishek A V 
Published: December 2021

Abstract
This paper presents a computer system for modelling one-dimensional random variables NMPUD, developed in the laboratory of mathematical modelling of Lyceum No. 130 in Novosibirsk. The results of the numerical experiments and the considerations justifying the practicability for using in the NMPUD system: the elementary densities constructed by the technology of sequential (inserted) substitutions, the densities representing weighted sums of elementary densities (which can be simulated using the modified discrete superposition method), the algorithms for a piecewise linear approximation of unknown densities using a given sample, the algorithms of the modified superposition method for computational modelling of random variables with piecewise linear densities, are also presented.
Numerical simulation of aerodynamic properties of separable elements of space-rocket systems in the LOGOS software package
Authors: Aksenov S V , Korchazhkin D A , Yu Puzan A , Puzan O A 
Published: December 2021

Abstract
The work describes simulation results of the aerodynamic properties of split elements of the space-rocket systems in the LOGOS software package: the review of the advanced methods for aerodynamic properties has been carried out, the advantages of the computer simulation when solving such problems were demonstrated, verification and validation computations of the simulation problems for the split elements were performed, the produced results were compared with the reference data from available publications. The analysis of the results confirmed the applicability of the LOGOS software package for computing aerodynamic properties of the split elements.
Rotatable LYSO-GAPD DEXA detector for providing improved spatial resolution
Authors: Heo H. , Yang J. , Kang J. 
Published: December 2021

Abstract
A rotatable
lutetium-yttrium-oxyorthosilicate-Geiger-mode-avalanche photodiode
(LYSO-GAPD) DEXA detector that can be configured into either a
normal-resolution or a high-resolution mode, was proposed and
examined. A 3 × 3 × 2 mm3 LYSO was coupled to a
3 × 3 mm2 GAPD. The versatile transformation of the
high-resolution mode was possible by employing the rotating
controller for the DEXA detector on its own axis, and the intrinsic
resolution in this mode was improved by ∼ 33% compared to the
normal-resolution mode. Dual-energy X-ray spectra and imaging
capabilities were evaluated in both acquisition modes. The
respective peak positions of low- and high-energy-beam of
normal-resolution mode (high-resolution mode) were 1330 mV
(1262 mV) and 2347 mV (2267 mV). The respective peak-to-valley
ratios of low- and high-energy-beam of normal-resolution mode
(high-resolution mode) were ∼ 2.8 (∼ 2.9) and ∼ 1.2
(∼ 1.1). Considerable improvements in phantom images such as
overall contrast and fine-spot detectability were observed in the
high-resolution mode. It should be noted that spatial resolution was
improved by reducing the detection-area from 3 × 3 mm2
to 2 × 3 mm2 in the high-resolution mode, but count
rate was also decreased. These results demonstrated that a rotatable
LYSO-GAPD DEXA detector allows to provide high versatility for both
high-resolution mode and normal-resolution mode with a single
detector.
SiPM dynamic range for CEPC scintillator-based electromagnetic calorimeter
Authors: Niu Y. , Shi Y. , Zhao H. , Zhang Y. , Ruan M. , Liu J. 
Published: December 2021

Abstract
A high-granularity scintillator calorimeter readout with
silicon photomultipliers (SiPMs) is an electromagnetic calorimeter
(ECAL) candidate for experiments at the Circular Electron Positron
Collider (CEPC). A critical design parameter of this ECAL candidate
is the dynamic range of the SiPMs. This study investigates the SiPM
dynamic range required for the CEPC scintillator ECAL. A model is
developed on the basis of the operation principles of SiPMs to
describe the response of an SiPM to light pulses within one recovery
period by considering the cross-talk effect, photon detection
efficiency, and number of pixels. The response curve of a
10000-pixel SiPM predicted by the model is consistent with the
measured curve within 2% for an incident light pulse of up to
12000 photons. The intrinsic fluctuations of the SiPM response
naturally exist in this model, and the correction of the saturation
effect in the SiPM response is investigated. Monte Carlo (MC)
simulation shows that the algorithm can restore the response
linearity of an SiPM for an incident light pulse in which the number
of photons is up to around six times the number of SiPM pixels. The
model and correction program are implemented for full simulation of
the ZH production Z → νν,
H → γγ channel to evaluate the impact
of the SiPM dynamic range of the CEPC scintillator ECAL on the
reconstructed Higgs boson mass and the sensitivity to the Higgs
signal in this channel. The results show that the CEPC scintillator
ECAL equipped with no less than 4000 SiPM pixels and operated with a
light yield of 20 photon-electrons per channel for a single minimum
ionizing particle can meet the requirements for Higgs boson
precision measurement in the di-photon channel at the CEPC.