bluuebunny/crossref_metadata_2025_split huggingface dataset:
A corpus-based investigation of semantic and syntactic differences between the two major future tense constructions
Authors: Yeh Tzu-Fen 
Published: January 2021

AbstractEnglish has two major future tense constructions,willandbe going to. Additionally, English can also use the present tense with a future-marking adverbial to express futurity. However, the distributions of these future markers are not free but limited. Instead of discriminating the differences among these distributions through direct comparison to etymological meanings or intuitive examples, this study offers an account for the semantic and syntactic differences between the two major English future tense constructions by analyzing data retrieved from the British National Corpus (BNC). The focus of attention is chiefly on the semantic and syntactic differences that lead to the choices British English native speakers make when expressing futurity. Based on the empirical analysis of data from the BNC, this study demonstrates that distribution of the future tense constructions seems sensitive to the following factors: (1) event-time orientation (temporal posteriority) or present-time orientation (prospective aspect), (2) the levels of verbal dynamicity in the whole sentence, (3) contexts of subordination, and (4) different text categories. The analysis suggests that the futurity constructions are not in the same distribution but are semantically and syntactically different. Utilizing its findings, this study aims to enhance second language learners’ expression of futurity by providing pedagogical suggestions.
Unitarity and the information problem in an explicit model of black hole evaporation
Authors: Schindler Joseph , Frangipane Evan , Aguirre Anthony 
Published: January 2021

Abstract
We consider the black hole information problem in an explicitly defined spacetime modeling black hole evaporation. Using this context we review basic aspects of the problem, with a particular effort to be unambiguous about subtle topics, for instance precisely what is meant by entropy in various circumstances. We then focus on questions of unitarity, and argue that commonly invoked semiclassical statements of long term, evaporation time, and Page time ‘unitarity’ may all be violated even if physics is fundamentally unitary. This suggests that there is no horizon firewall. We discuss how the picture is modified for regular (nonsingular) evaporation models. We also compare our conclusions to recent holographic studies, and argue that they are mutually compatible.
Geometric mean of bimetric spacetimes
Authors: Kocic Mikica 
Published: January 2021

Abstract
We use the geometric mean to parametrize metrics in the Hassan–Rosen ghost-free bimetric theory and pose the initial-value problem. The geometric mean of two positive definite symmetric matrices is a well-established mathematical notion which can be under certain conditions extended to quadratic forms having the Lorentzian signature, say metrics g and f. In such a case, the null cone of the geometric mean metric h is in the middle of the null cones of g and f appearing as a geometric average of a bimetric spacetime. The parametrization based on h ensures the reality of the square root in the ghost-free bimetric interaction potential. Subsequently, we derive the standard n + 1 decomposition in a frame adapted to the geometric mean and state the initial-value problem, that is, the evolution equations, the constraints, and the preservation of the constraints equation.
Symmetry restriction and its application to gravity
Authors: Kamiński Wojciech , Liegener Klaus 
Published: January 2021

Abstract
In the Hamiltonian formulation, it is not a priori clear whether a symmetric configuration will keep its symmetry during evolution. In this paper, we give precise requirements of when this is the case and propose a symmetry restriction to the phase space of the symmetric variables. This can often ease computation, especially when transcending from the infinite dimensional phase space of a field theory to a possibly finite dimensional subspace. We will demonstrate this in the case of gravity. A prominent example is the restriction of full general relativity in its Hamiltonian formulation to the cosmological configurations of Robertson–Walker type. We will demonstrate our procedure in this setting and extend it to examples that appear useful in certain approaches to quantum gravity.
Infinite degeneracy of Landau levels from the Euclidean symmetry with central extension revisited
Authors: Murgan Rajan 
Published: January 2021

Abstract
The planar Landau system which describes the quantum mechanical motion of a charged particle in a plane with a uniform magnetic field perpendicular to the plane, is explored within pedagogical settings aimed at the beginning graduate level. The system is known to possess the Euclidean symmetry in two dimensions with central extension

E

̄

(

2

)

. In this paper, we revisit the well-known energy eigenvalues of the system, known as the Landau levels, by exploiting the related

e

̄

(

2

)

symmetry algebra. Specifically, we utilize the Casimir operator and the commutation relations of the generators of the

E

̄

(

2

)

group. More importantly, an algebraic formalism on this topic based on Schwinger’s oscillator model of angular momentum is also presented. The dimensions of irreducible representations of the

E

̄

(

2

)

group and their implications on the degeneracy of Landau levels is discussed.
BAlN for III-nitride UV light-emitting diodes: undoped electron blocking layer
Authors: Gu Wen , Lu Yi , Lin Rongyu , Guo Wenzhe , Zhang Zihui , Ryou Jae-Hyun , Yan Jianchang , Wang Junxi , Li Jinmin , Li Xiaohang 
Published: January 2021

Abstract
The undoped BAlN electron-blocking layer (EBL) is investigated to replace the conventional AlGaN EBL in light-emitting diodes (LEDs). Numerical studies of the impact of variously doped EBLs on the output characteristics of LEDs demonstrate that the LED performance shows heavy dependence on the p-doping level in the case of the AlGaN EBL, while it shows less dependence on the p-doping level for the BAlN EBL. As a result, we propose an undoped BAlN EBL for LEDs to avoid the p-doping issues, which a major technical challenge in the AlGaN EBL. Without doping, the proposed BAlN EBL structure still possesses a superior capacity in blocking electrons and improving hole injection compared with the AlGaN EBL having high doping. Compared with the Al0.3Ga0.7N EBL with a doping concentration of 1 × 1020 cm−3, the undoped BAlN EBL LED still shows lower droop (only 5%), compatible internal quantum efficiency (2% enhancement), and optical output power (6% enhancement). This study provides a feasible route to addressing electron leakage and insufficient hole injection issues when designing ultraviolet LED structures.
Diffusion charging of nanometer-sized liquid aerosol particles
Authors: Yang Yong , Zhang Haoqin , Li Chuan , Li Chi , Yu Ziheng , Yu Kexun 
Published: January 2021

Abstract
Aerosol particles play an important role in atmospheric physical or chemical reactions. Charging of aerosol particles is also widely used in various engineering applications, such as electrical low-pressure impactors and differential mobility analyzers. In this paper, the charging process of nanometer-sized liquid aerosol particles in an atmospheric environment is studied theoretically and experimentally. The traditional charging equation is modified taking the variation of carried charges and the number density of liquid aerosol particles into consideration, due to the coalescence of liquid aerosol particles that brings 100% charge conversion efficiency. By fitting the experimental data under a low discharge voltage, an appropriate combination (r, η) is selected, where r is a specific droplet radius and η is the corresponding equivalent conversion factor of charges. The results from the fitting combination (r, η) are in good agreement with the experimental data and it further demonstrates that the charging evolution of droplets with various radiuses under various voltages can be derived from the existing experimental data under a low voltage. In addition, the concept of a charging time constant τ
0.1 is introduced to describe the charging rate. This paper may provide a reference to reveal and optimize the charging process of liquid aerosol particles and broaden the engineering applications for the charging of aerosol particles.
Comparison of high-k Y2O3/TiO2 bilayer and Y-doped TiO2 thin films on Ge substrate
Authors: Kim Dong Gun , Kim Hae-Ryoung , Kwon Dae Seon , Lim Junil , Seo Haengha , Kim Tae Kyun , Paik Heewon , Lee Woongkyu , Hwang Cheol Seong 
Published: January 2021

Abstract
Y2O3/TiO2 bilayer thin films and Y-doped TiO2 (YTO) thin films were deposited on a Ge substrate by atomic layer deposition at a substrate temperature of 250 °C. They were used as gate insulators to examine the electrical properties of Pt/TiN/TiO2/Y2O3/p-Ge and Pt/TiN/YTO/p-Ge metal–oxide–semiconductor capacitors. A 7 nm thick bilayer thin film showed a lower leakage current density by more than one order of magnitude compared to a YTO thin film with the same thickness due to the high conduction band offset between the Y2O3 layer and Ge substrate. However, the bilayer thin film showed a large hysteresis of 950 mV. On the other hand, the YTO thin film showed significantly reduced hysteresis of 120 mV due to the smaller slow trap density. The voltage acceleration factors of the bilayer thin film and YTO thin film were 1.12 and 1.25, respectively, higher in the YTO thin film. The interfacial trap density of the 7 nm thick bilayer and YTO thin films were 3.5 × 1011 cm−2 eV−1 and 2.7 × 1011cm−2 eV−1, respectively. The equivalent oxide thickness of the YTO film could be scaled down to 0.9 nm, and a leakage current density of 1.4 × 10−4A cm−2 at flat band voltage −1 V was achieved. This study confirmed that the YTO film can be used as a promising ternary high-k oxide for a Ge-based field-effect-transistor.
Perpendicular magnetic anisotropy induced by La2/3Sr1/3MnO3–YBaCo2O5+δ
interlayer coupling
Authors: Han Furong , Chen Xiaobing , Wang Jianlin , Huang Xudan , Zhang Jine , Song Jinghua , Liu Banggui , Chen Yuansha , Bai Xuedong , Hu Fengxia , Shen Baogen , Sun Jirong 
Published: January 2021

Abstract
Heterostructure with a symmetry-mismatched interface provides a promising playground for the exploration of emergent phenomena. Herein, we report a systematic investigation on La2/3Sr1/3MnO3/YBaCo2O5+δ
(LSMO/YBCO) grown on SrTiO3, a heterostructure formed by perovskite oxides of different symmetry. A high-resolution lattice image shows the formation of high-quality perovskite LSMO and A-site cation-ordered oxygen-deficient double perovskite YBCO, without any signatures of atomic reconfiguration at the interface. Surprisingly, the YBCO-buffered LSMO exhibits perpendicular magnetic anisotropy (PMA), though bare LSMO film is in-plane anisotropic. The PMA is robust, appearing even when the thickness of YBCO is only one unit cell. The typical anisotropy constant is ∼4 × 106 erg cm−3. X-ray absorption spectroscopy analysis reveals a preferential occupation of the

d

3

z
2

−

r
2

orbital compared with

d

x
2

−

y
2

, which is confirmed by density functional theory calculations. This orbital reconstruction accounts for the PMA. The formation of a covalent bond between Mn and Co caged by different oxygen polyhedrons, an octahedron and a square pyramid, respectively, stabilizes the orbital reconstruction, resulting in anomalous spin orientation.
Study of the 33Cl spectroscopic factors via the 32S(3He, d)33Cl one-proton transfer reaction
Authors: Lombardo I , Dell'Aquila D , Cinausero M , Gasques L R , Vigilante M , Zagatto V A B , Barlini S , Bolzonella R , Bruno M , Buccola A , Camaiani A , Carturan S M , Casini G , Ciampi C , Cicerchia M , D'Andrea M , Degerlier M , Fabris D , Frosin C , Gramegna F , Lepine-Szily A , Maggioni G , Mantovani G , Marchi T , Ordine A , Ottanelli P , Pasquali G , Piantelli S , Rigato V , Russo M , Scomparin L , Valdrè S , Verde G 
Published: January 2021

Abstract
In this paper we discuss new experimental data on the one-proton transfer reaction 32S(3He, d)33Cl* at 9.68 MeV bombarding energy. An enriched 32S target and a high-granularity hodoscope were used to obtain data for proton transfer reactions to bound and unbound states in 33Cl. Angular distributions were interpreted by means of finite-range DWBA and coupled-channel calculations. The obtained spectroscopic factors have been compared with previous results reported in the literature and with shell model calculations.
Stabilities and catapults of truncated carbon nanocones
Authors: Dong Shuhong , Liu Jun , Zhang Zi-Yue , Li Yongheng , Huang Ruiyu , Zhao Junhua 
Published: January 2021

Abstract
Truncated carbon nanocones (CNCs) can be taken as energy suppliers because of their special structures. In this paper, we demonstrate the stability of truncated CNCs under compression and the escape behavior of a fullerene catapulted from a compressed CNC by molecular dynamics simulations and theoretical models. The strain energy of a CNC and cohesive energy between a fullerene and the CNC (due to their van der Waals interactions) dominate the stability and catapulting capability of the cone, which strongly depend on geometrical parameters (apex angle, top radius and height) of each CNC and axial distances between them. In particular, the additional transverse vibration of buckled CNCs after released plays a significant role in their catapulting abilities and efficiencies. Finally, finite element method and experiments are further performed to validate the escape mechanism. This study should be of great importance to providing a theoretical support for designing novel nanodevices in mico/nanoelectromechanical systems.
Introducing ferromagnetism and anisotropic magnetoresistance in monolayer CVD graphene by nitrogen doping
Authors: Singla Robin , Shukla Ambika Shankar , Kottantharayil Anil 
Published: January 2021

Abstract
We demonstrate a method to dope monolayer chemical vapor deposited (CVD) graphene with nitrogen and make it ferromagnetic. CVD graphene was first functionalized with hydroxyl groups by treating with H2O2 in the presence of UV light and then annealed in ammonia gas to dope it with nitrogen. Magnetization measurements showed a ferromagnetic hysteresis loop at low temperatures with a coercivity of 222 Oe at 2 K. We also investigated the effect of a change in the angle of the applied magnetic field on the anisotropic magnetoresistance effect (AMR) in the doped CVD graphene devices. Graphene shows positive AMR for temperatures from 2 K to 50 K, negative AMR at 100 K and 150 K, and no AMR for temperatures higher than 150 K. A maximum AMR of 0.92% was observed at 2 K for an in-plane magnetic field of 30 kOe. Magnetic force microscopy also confirms the introduction of magnetism in CVD graphene after doping, and electron spin resonance spectroscopy shows resonance when scanned in a magnetic field, which confirms the presence of unpaired electrons in doped graphene. The process introduced in this paper for nitrogen doping of graphene with attendant magnetism could pave the way for the applications of graphene in spintronics and other devices.
Composites of ion-in-conjugation polysquaraine and SWCNTs for the detection of H2S and NH3 at ppb concentrations
Authors: Zhou Jin , Järvinen Topias , Pitkänen Olli , Kónya Zoltán , Kukovecz Akos , Kordas Krisztian 
Published: January 2021

Abstract
Several different methods are established for the analysis of gases, including optical spectroscopy, photoacoustic spectroscopy as well as colorimetric and resistive sensing, the measurements systems are either too complex or have limited sensitivity. In particular, when the goal is to apply a large number of sensors in networks, it is highly desirable to have devices that are simple, have low cost and energy consumption, yet sensitive and selective to monitor analytes even in traces. Herein, we propose a new type of resistive sensor device based on a composite of single-wall carbon nanotubes and an ion-in-conjugation polymer, poly(1,5-diaminonaphthalene-squaraine), capable of detecting H2S and NH3 in air even at room temperature with a theoretical concentration limit of ∼1 ppb and ∼7 ppb, respectively. Density functional theory calculations revealed that H atoms of the analytes and O atoms of the polymer chain interact and form hydrogen bonds, and the electron withdrawal from the gas molecules by the polymer chain results in the change of its electrical conductivity. To demonstrate the feasibility of the new nanocomposites in sensing, we show the devices for monitoring food safety with good sensor stability of operation for at least 3 months of period of time.
Imaging the response to deep brain stimulation in rodent using functional ultrasound
Authors: Nayak Rohit , Lee Jeyeon , Chantigian Siobhan , Fatemi Mostafa , Chang Su-Youne , Alizad Azra 
Published: January 2021

Abstract
In this study, we explored the feasibility of using functional ultrasound (fUS) imaging to visualize cerebral activation associated with thalamic deep brain stimulation (DBS), in rodents. The ventrolateral (VL) thalamus was stimulated using electrical pulses of low and high frequencies of 10 and 100 Hz, respectively, and multiple voltages (1–7 V) and pulse widths (50–1500 μs). The fUS imaging demonstrated DBS-evoked activation of cerebral cortex based on changes of cerebral blood volume, specifically at the primary motor cortex (PMC). Low frequency stimulation (LFS) demonstrated significantly higher PMC activation compared to higher frequency stimulation (HFS), at intensities (5–7 V). Whereas, at lower intensities (1–3 V), only HFS demonstrated visible PMC activation. Further, LFS-evoked cerebral activation was was primarily located at the PMC. Our data presents the functionality and feasibility of fUS imaging as an investigational tool to identify brain areas associated with DBS. This preliminary study is an important stepping stone towards conducting real-time functional ultrasound imaging of DBS in awake and behaving animal models, which is of significant interest to the community for studying motor-related disorders.
A 4D flow cardiovascular magnetic resonance study of flow asymmetry and haemodynamic quantity correlations in the pulmonary artery
Authors: Gbinigie Henrike , Coats Louise , Parikh Jehill D , Hollingsworth Kieren G , Gan Lian 
Published: January 2021

AbstractObjective. In this paper we elucidate the asymmetric flow pattern and the haemodynamic quantity distributions and correlations in the pulmonary artery (PA) vasculature in healthy adults having structurally normal hearts, to provide reference on the flow characteristics in the PA and the right ventricle.Approach. Velocity data are acquired non-invasively from 18 healthy volunteers by 4D flow magnetic resonance imaging, resolved to 20 phases with spatial resolution 3 × 3 × 3 mm3. Interpolation is applied to improve the accuracy in quantifying haemodynamic quantities including kinetic energy, rotational energy, helicity and energy dissipation rate. These quantities are volumetrically normalised to remove size dependency, representing densities or local intensity.Main results. Flow asymmetry in the PA is quantified in terms of all the flow dynamic quantities and their correlations. The right PA has larger diameter and higher peak stroke velocity than the left PA. It also has the highest rotational energy intensity. Counter-rotating helical streams in the main PA appear to be associated with the unidirectional helical flow noticed in the left and the right PA near the peak systole.Significance. This study provides a fundamental basis of normal flow in the PA. It implies the validity to use these flow pattern-related quantitative measures to aid with the identification of abnormal PA flow non-invasively, specifically for detecting abnormalities in the pulmonary circulation and response to therapy, where haemodynamic flow is commonly characterised by increased vortical and helical formations.
Capacitively-coupled ECG and respiration for the unobtrusive detection of sleep apnea
Authors: Deviaene Margot , Castro Ivan D , Borzée Pascal , Patel Aakash , Torfs Tom , Buyse Bertien , Testelmans Dries , Van Huffel Sabine , Varon Carolina 
Published: January 2021

Abstract

Objective. The performance of a novel unobtrusive system based on capacitively-coupled electrocardiography (ccECG) combined with different respiratory measurements is evaluated for the detection of sleep apnea. Approach. A sleep apnea detection algorithm is proposed, which can be applied to electrocardiography (ECG) and ccECG, combined with different unobtrusive respiratory measurements, including ECG derived respiration (EDR), respiratory effort measured using the thoracic belt (TB) and capacitively-coupled bioimpedance (ccBioz). Several ECG, respiratory and cardiorespiratory features were defined, of which the most relevant ones were identified using a random forest based backwards wrapper. Using this relevant feature set, a least-squares support vector machine classifier was trained to decide if a one minute segment is apneic or not, based on the annotated polysomnography (PSG) data of 218 patients suspected of having sleep apnea. The obtained classifier was then tested on the PSG and capacitively-coupled data of 28 different patients. Main results. On the PSG data, an AUC of 76.3% was obtained when the ECG was combined with the EDR. Replacing the EDR with the TB led to an AUC of 80.0%. Using the ccECG and ccBioz or the ccECG and TB resulted in similar performances as on the PSG data, while using the ccECG and ccECG-based EDR resulted in a drop in AUC to 67.4%. Significance. This is the first study which tests an apnea detection algorithm on capacitively-coupled ECG and bioimpedance signals and shows promising results on the capacitively-coupled data set. However, it was shown that the EDR could not be accurately estimated from the ccECG signals. Further research into the effect that respiration has on the ccECG is needed to propose alternative EDR estimates.
Experimental demonstration of plasma mass separation in a configuration with a potential well and crossed electric and magnetic fields
Authors: Liziakin G , Antonov N , Usmanov R , Melnikov A , Timirkhanov R , Vorona N , Smirnov V S , Oiler A , Kislenko S , Gavrikov A , Smirnov V P 
Published: January 2021

Abstract
One of the alternative ‘dry’ methods for spent nuclear fuel (SNF) reprocessing is the plasma mass separation technique. This letter describes the first experiments that demonstrate the fundamental feasibility of a plasma mass separation approach in crossed electric and magnetic fields in collisionless mode. The Ag + Pb mixture was used to simulate the heavy (>235 u) and light (<150 u) components of the SNF. The Ag + Pb mixture was transformed into a plasma jet and ejected along the magnetic field. The action of the electric field caused the deposition of mixture components on the substrate in the form of localized spots. The estimated separation factor was of 35.