bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strained agricultural farming under the stress of youths’ career selection tendencies: a case study from Hokkaido (Japan)
Authors: Usman Muhammad , Sawaya Akinori , Igarashi Mari , Gayman Jeffry Joseph , Dixit Rakesh 
Published: January 2021

AbstractAlthough job availability in Japan is at its highest in 24 years, the unemployment rate has remained unchanged. On one hand, certain fields are saturated with employees while on the other hand, the rural areas of Hokkaido are in desperate need of agricultural workers. At the same time, the aging population in Japan is an emerging challenge. The flat unemployment rate in conjunction with the rapidly aging farmers’ population can possibly reduce the food self-sufficiency rate, raise Japan’s dependency for international food products and increase import expenses. Thus, these factors can tip the socio-economic balance of the struggling economy. For the present research, different surveys were conducted not only in various farming corporations of Hokkaido but also 20 farmers were directly contacted and interviewed. In addition, adolescents’ (aged 16–18 years) career choices were studied through questionnaires administered to 157 students at Hokkaido’s Sapporo Kaisei Secondary School. It was found that, in rural areas of Hokkaido, relocation of youth to the cities is probably the main cause of the shortage of workers. In Sapporo city, among adolescents who had already chosen a career path, around 76% wanted to enter the science and technology field. This trend can result in intense competition and “saturation” in science and technology fields and many vacant slots in the others related to agricultural farming. This behavior is probably maintaining the unemployment rate, regardless of the number of job vacancies. In addition, according to our survey, considering career paths, parents and teachers provide general guidance that has very little influence on adolescents’ career decisions. So, a more detailed career counseling is suggested.
The use of le 了 in Mandarin Chinese oral discourse
Authors: Li Xiaoshi , Li Wenjing , Cui Yaqiong 
Published: January 2021

Abstractleis the mostly widely studied aspect marker in Chinese. In addition to perfective aspect marker to indicate action completion,lecan also serve as a sentence-final particle to indicate a currently relevant state. This study investigates how Chinese native speakers uselein oral discourse and the factors that influence their use. The data were collected from three discourses including informal conversations, elicited narratives, and teacher classroom speech. Multivariate analysis of 2,359 tokens revealed that verb complement type and verb type have the strongest effects, followed byleposition, serial verb relationship, sentence type, discourse context, and time word presence/absence.
Multipole polarizabilities and critical phenomena of hydrogen-like atoms in dense quantum plasmas
Authors: Jiao Li Guang , He Yu Ying , Zhang Yong Zhi , Ho Yew Kam 
Published: January 2021

Abstract
Binding energies, oscillator strengths, and polarizabilities of hydrogen-like atoms embedded in dense quantum plasmas are calculated in high precision by employing the generalized pseudospectral method. Benchmark predictions of these quantities are obtained for both the ground and excited states including high-order transitions. The critical behaviour of system eigenenergies, radial mean values, oscillator strengths, and multipole polarizabilities for bound states when they approach to the corresponding continuum limit as increasing the plasma screening strength are investigated in detail. It is shown that near the critical screening parameters the quantities in s-wave states show distinct behaviour from those in non-s states and such phenomenon is attributed to the divergent asymptotic form of wave functions caused by the centrifugal potential of orbital angular momentum. Based on the power laws of energies and radial mean values extracted from numerical calculations and the approximate formulae for dipole polarizabilities, the critical behaviour of the 2
k
-pole polarizability of s-wave states is explicitly derived and numerically validated to follow a power law with the exponent −2(k + 1).
Introducing an effective method for extending the high harmonic spectrum plateau from gas targets
Authors: Khodabandeh Z , Monfared M , Ara M H Majles , Sadighi-Bonabi R 
Published: January 2021

Abstract
An effective semi-classical method is introduced for controlling the high-order harmonic generation process and extending the cutoff frequency. This method is capable of defining the proper specification of the driving laser for maximizing the cutoff frequency. This method is evaluated by examining the high harmonic spectrum from the hydrogen atom and the fluorine (F2) molecule irradiated by single-, two-, and three-color laser fields. This study is done using the time-dependent density functional theory in a three-dimensional space. The results show that the single-, two-, and three-color laser pulses tuned by proper specifications could extend the cutoff frequency by up to 85%, 176%, and 241% compared to their non-tuned forms, respectively. Also, single attosecond pulses with a duration of 161 as and 129 as are obtained by applying the tuned three-color laser for the hydrogen atom and the fluorine molecule, respectively.
The role of radio frequency scattering in high-energy electron losses from minimum-B ECR ion source
Authors: Izotov I V , Shalashov A G , Skalyga V A , Gospodchikov E D , Tarvainen O , Mironov V E , Koivisto H , Kronholm R , Toivanen V , Bhaskar B 
Published: January 2021

Abstract
The measurement of the axially lost electron energy distribution escaping from a minimum-B electron cyclotron resonance ion source in the range of 4–800 keV is reported. The experiments have revealed the existence of a hump at 150–300 keV energy, containing up to 15% of the lost electrons and carrying up to 30% of the measured energy losses. The mean energy of the hump is independent of the microwave power, frequency and neutral gas pressure but increases with the magnetic field strength, most importantly with the value of the minimum-B field. Experiments in pulsed operation mode have indicated the presence of the hump only when microwave power is applied, confirming that the origin of the hump is radio-frequency-induced momentum space diffusion. A possible mechanism of the hump formation is considered based on the quasi-linear model of plasma–wave interaction.
Flow in an hourglass: particle friction and stiffness matter
Authors: Pongó Tivadar , Stiga Viktória , Török János , Lévay Sára , Szabó Balázs , Stannarius Ralf , Hidalgo Raúl Cruz , Börzsönyi Tamás 
Published: January 2021

Abstract
Granular flow out of a silo is studied experimentally and numerically. The time evolution of the discharge rate as well as the normal force (apparent weight) at the bottom of the container is monitored. We show that particle stiffness has a strong effect on the qualitative features of silo discharge. For deformable grains with a Young modulus of about Y
m ≈ 40 kPa in a silo with basal pressure of the order of 4 kPa, lowering the friction coefficient leads to a gradual change in the discharge curve: the flow rate becomes filling height dependent, it decreases during the discharge process. For hard grains with a Young modulus of about Y
m ≈ 500 MPa the flow rate is much less sensitive to the value of the friction coefficient. Using DEM data combined with a coarse-graining methodology allows us to compute all the relevant macroscopic fields, namely, linear momentum, density and stress tensors. The observed difference in the discharge in the low friction limit is connected to a strong difference in the pressure field: while for hard grains Janssen-screening is effective, leading to high vertical stress near the silo wall and small pressure above the orifice region, for deformable grains the pressure above the orifice is larger and gradually decreases during the discharge process. We have analyzed the momentum balance in the region of the orifice (near the location of the outlet) for the case of soft particles with low friction coefficient, and proposed a phenomenological formulation that predicts the linear decrease of the flow rate with decreasing filling height.
Tkwant: a software package for time-dependent quantum transport
Authors: Kloss Thomas , Weston Joseph , Gaury Benoit , Rossignol Benoit , Groth Christoph , Waintal Xavier 
Published: January 2021

Abstract
Tkwant is a Python package for the simulation of quantum nanoelectronics devices to which external time-dependent perturbations are applied. Tkwant is an extension of the kwant package (https://kwant-project.org/) and can handle the same types of systems: discrete tight-binding-like models that consist of an arbitrary central region connected to semi-infinite electrodes. The problem is genuinely many-body even in the absence of interactions and is treated within the non-equilibrium Keldysh formalism. Examples of Tkwant applications include the propagation of plasmons generated by voltage pulses, propagation of excitations in the quantum Hall regime, spectroscopy of Majorana fermions in semiconducting nanowires, current-induced skyrmion motion in spintronic devices, multiple Andreev reflection, Floquet topological insulators, thermoelectric effects, and more. The code has been designed to be easy to use and modular. Tkwant is free software distributed under a BSD license and can be found at https://tkwant.kwant-project.org/.
2D self-interacting magnetically confined electrons
Authors: Bruce S A , Diaz-Valdes J F 
Published: January 2021

Abstract
We investigate the nonlinear dynamics of electrons in the presence of an external homogeneous magnetic field in 2 + 1 flat space-time dimensions. Two regimes of magnetic fields are examined: high laboratory fields and strong-QED fields. We provide the (nonlinear) ground-state Landau energy levels together with their respective eigenfunctions. We comment on the relevance of this (toy) model to reveal certain processes thought to occur near the surfaces of neutron stars.
Electrical conductivity of a thin film in the case of an arbitrarily oriented ellipsoidal isoenergetic surface of a conductor
Authors: Kuznetsova I A , Romanov D N , Savenko O V 
Published: January 2021

Abstract
The static electrical conductivity of a thin conducting film is calculated using the kinetic approach. The model of diffuse boundary conditions is used as boundary conditions for the charge carrier distribution function. The isoenergetic surface of the conducting film material is an ellipsoid of rotation that is arbitrarily oriented in the pulse space. The volume of the conductor is dominated by scattering on impurity atoms and on dislocations of electrons (holes). The electrical conductivity of the film is analyzed depending on the angles that determine the direction of the ellipsoid axis of rotation, and a comparison with the results for the case of a macroscopic sample is presented. A comparison is made with experimental data for the electrical conductivity of Bi and Si thin films.
Entropy scrutiny of couple stress nanoliquid flow with slip and convective conditions in an upright microchannel
Authors: B J Gireesha , Venkatesh P , F Almeida 
Published: January 2021

Abstract
This article delves into the steady flow of couple stress nanoliquid by applying the magnetic field in conjunction with the resultant entropy produced in an upright microchannel which is immersed with Titanium-dioxide nano-sized particles with water being base fluid. Both the walls facilitate injection and suction of the fluid. The entropy generated and Bejan number is figured out by making use of velocity and temperature profiles. The coalesce sequel of nanoparticle volume fraction, magnetic field, linear thermal radiation and buoyancy force along with heat source/sink are taken into account. The equations governing the fluid flow are formulated under the impact of viscous dissipation and the numerical computations of the non-linear equations are made by using the shooting technique together with Runge–Kutta–Fehlberg fourth-fifth scheme. The effect of the viscous dissipation, Grashof number, Hartmann number and couple stress parameter on nanoliquid flow and thermal distributions are thrashed out and exposed graphically. The results indicate that peak values of couple stress parameter diminishes the velocity, temperature and entropy profile whereas amplifies the Bejan number. Also lower values of Hartmann number and nanoparticle volume fraction promotes the flow and higher values of heat source parameter and Peclet number exhibits augmentation in the thermal profile.
Interplay between neutrino and gravity portals for FIMP dark matter
Authors: Chianese Marco , Fu Bowen , King Stephen F. 
Published: January 2021

Abstract
In the classic type I seesaw mechanism with very heavy right-handed (RH) neutrinos, it is possible to account for dark matter via RH neutrino portal couplings to a feebly interacting massive particle (FIMP) dark sector. However, for large RH neutrino masses, gravity can play an important role. We study the interplay between the neutrino portal through the right-handed neutrinos and the gravity portal through the massless spin-2 graviton in producing dark matter particles in the early universe. As a concrete example, we consider the minimal and realistic Littlest Seesaw model with two RH neutrinos, augmented with a dark scalar and a dark fermion charged under a global U(1)_D dark symmetry. In the model, the usual seesaw neutrino Yukawa couplings and the right-handed neutrino masses (the lightest being about 5× 10^10 GeV) are fixed by neutrino oscillations data and leptogenesis. Hence, we explore the parameter space of the two RH neutrino portal couplings, the two dark particle masses and the reheating temperature of the universe, where the correct dark matter relic abundance is achieved through the freeze-in mechanism. In particular, we highlight which class of processes dominate the dark matter production. We find that, despite the presence of the gravity portal, the dark matter production relies on the usual seesaw neutrino Yukawa coupling in some regions of the parameter space, so realising a direct link between dark matter and neutrino phenomenology. Finally, we report the threshold values for the neutrino portal couplings below which the neutrino portal is irrelevant and the Planckian Interacting Dark Matter paradigm is preserved.
Speech stream segregation to control an ERP-based auditory BCI
Authors: Velasco-Álvarez Francisco , Fernández-Rodríguez Álvaro , Medina-Juliá M Teresa , Ron-Angevin Ricardo 
Published: January 2021

Abstract

Objective. The use of natural sounds in auditory brain–computer interfaces (BCI) has been shown to improve classification results and usability. Some auditory BCIs are based on stream segregation, in which the subjects must attend one audio stream and ignore the other(s); these streams include some kind of stimuli to be detected. In this work we focus on event-related potentials (ERP) and study whether providing intelligible content to each audio stream could help the users to better concentrate on the desired stream and so to better attend the target stimuli and to ignore the non-target ones. Approach. In addition to a control condition, two experimental conditions, based on the selective attention and the cocktail party effect, were tested using two simultaneous and spatialized audio streams: (a) the condition A2 consisted of an overlap of auditory stimuli (single syllables) on a background consisting of natural speech for each stream, (b) in condition A3, brief alterations of the natural flow of each speech were used as stimuli. Main results. The two experimental proposals improved the results of the control condition (single words as stimuli without a speech background) both in a cross validation analysis of the calibration part and in the online test. The analysis of the ERP responses also presented better discriminability for the two proposals in comparison to the control condition. The results of subjective questionnaires support the better usability of the first experimental condition. Significance. The use of natural speech as background improves the stream segregation in an ERP-based auditory BCI (with significant results in the performance metrics, the ERP waveforms, and in the preference parameter in subjective questionnaires). Future work in the field of ERP-based stream segregation should study the use of natural speech in combination with easily perceived but not distracting stimuli.
Radial electric field and density fluctuations measured by Doppler reflectometry during the post-pellet enhanced confinement phase in W7-X
Authors: Estrada T. , Carralero D. , Windisch T. , Sánchez E. , García-Regaña J.M. , Martínez-Fernández J. , de la Peña A. , Velasco J.L. , Alonso J.A. , Beurskens M. , Bozhenkov S. , Damm H. , Fuchert G. , Kleiber R. , Pablant N. , Pasch E. , W7-X team the 
Published: January 2021

Abstract
Radial profiles of density fluctuations and the radial electric field, E
r, have been measured using Doppler reflectometry during the post-pellet enhanced confinement phase achieved, under different heating power levels and magnetic configurations, during the 2018 W7-X experimental campaign. A pronounced E
r-well is measured with local values as high as −40 kV m−1 in the radial range ρ ∼ 0.7–0.8 during the post-pellet enhanced confinement phase. The maximum E
r intensity scales with both the plasma density and electron cyclotron heating power level, following a similar trend to the plasma energy content. A good agreement is found when the experimental E
r profiles are compared to simulations carried out using the neoclassical codes, the drift kinetic equation solver (DKES) and kinetic orbit-averaging solver for stellarators (KNOSOS). The density fluctuation level decreases from the plasma edge toward the plasma core and the drop is more pronounced in the post-pellet enhanced confinement phase than in reference gas-fuelled plasmas. Besides, in the post-pellet phase, the density fluctuation level is lower in the high iota magnetic configuration than in the standard one. To determine whether this difference is related to the differences in the plasma profiles or to the stability properties of the two configurations, gyrokinetic simulations have been carried out using the codes stella and EUTERPE. The simulation results point to the plasma profile evolution after the pellet injection and the stabilization effect of the radial electric field profile as the dominant players in the stabilization of the plasma turbulence.
Regime searching in time series data using Variational Autoencoder
Authors: Prosvetov Artem 
Published: January 2021

AbstractIn the current work we propose a method to extract regimes from time series using unsupervised learning. The proposed method is based on neural network with architecture of variational autoencoder and clusterization in latent space. The method has been proven by extracting regimes from a steam turbine telemetry data set and from human activity recognition data, which suggests that the proposed approach can extract regimes from time series data obtained for different areas.
Diffusion Model for Forecasting Events in News Feeds
Authors: Zhukov Dmitriy , Andrianova Elena , Novikova Olga 
Published: January 2021

Abstract
On the basis of the diffusion theory, we suggested a model for forecasting event in news feeds, which is based on the use of stochastic dynamics of changes in the structure of non-stationary time series in news text clusters (states of the information space). Forecasting events in a news feed is based on their text description, vectorization, and finding the cosine value of the angle between the given vector and the centroids of various information space semantic clusters. Changes over time in the cosine value of such angle between the above vector and centroids can be represented as a point wandering on [0,1] segment. This segment contains a trap at the event occurrence threshold point. The wandering point can fall into this trap over time. We have considered probability patterns of transitions between states in the information space. We have derived a nonlinear second-order differential equation; formulated and solved the boundary value problem of forecasting news events. We have obtained theoretical time dependence for the probability density function of the parameter distribution of non-stationary time series that describe the information space evolution. The results of simulating the time dependence of the event probability (with sets of parameter values of the developed model, which have been experimentally determined for already occurred events) show that the model is consistent and adequate. Experimental verification of the proposed model was carried out using a corpus of texts written in Russian.
Predicting nonverbal intelligence level from resting-state connectivity: a neural networks approach
Authors: Ivanov S A , Zakharov I M , Feklicheva I V , Ismatullina V I , Chipeeva N A , Alkapov R R , Bessonov V V , Buraya A A , Starkov A E , Malykh S M 
Published: January 2021

Abstract
This article is devoted to the development of a model of an artificial neural network for predicting the level of nonverbal intelligence according to the EEG of the brain. Cognitive functioning relies on the synchronization between different brain structures. However, it is still unclear how individual differences in intelligence are related to the global characteristics of information transmission in brain networks. Resting-state functional connectivity studies show the association of patterns of interactions between brain regions from people and different levels of nonverbal intelligence. In this study, we present a process of development of a neural network model used to predict the level of nonverbal intelligence based on EEG data of the brain. We have developed a fully-connected neural network to predict the level of nonverbal intelligence.
Cluster approach to analysis of publication titles
Authors: Bogomolova Arina , Ryazanova Maria , Balk Igor 
Published: January 2021

Abstract
Text analysis is a promising field of study with many unsolved problems. First of all, most methods are labor and time consuming. We want to pay special attention to patents. The most important thing in analyzing patents as a reflection of a company’s research activities is not to be late. Technology is emerging very quickly. So speed of response to changes in the world of scientific research is very important now. Therefore, we propose an alternative method of patent analysis based on clustering. Its main advantage is that it does not require different train/test datasets and it could be applied immediately. In this article, we compare different clustering algorithms, because the quality of the conclusions depends on it.
Inspection of corrosion defects of steel pipes by eddy current method
Authors: Ishkov A V , Dmitriev S F , Katasonov A O , Fadeev D A , Malikov V N 
Published: January 2021

Abstract
The article describes the results of testing a known non-destructive eddy current inspection method intended for non-destructive testing of steel pipelines. The analysis of the operational capabilities and features of this type of test objects showed the need for the development of new approaches in the field of creation of measuring sensors and software-hardware systems for pipelines’ technical inspection. The feasibility of creation of a measuring system capable of searching for defects with the diameters from 0.2 mm located at a depth of 2 mm is demonstrated. In the proposed method and its schematic design, the impact of a defect on the magnitude of the transformer EMF induced in the measuring winding of the eddy-current sensor is used. The article investigates the influence of the size and depth of the defect on the eddy-current sensor EMF and analyzes the influence of these parameters on the obtained signal dependences in order to determine the defect parameters.