bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation failure in discrete reaction–diffusion system based on the butterfly bifurcation
Authors: Rohe K. , Cisternas J.
Published: May 2022

Reaction–diffusion systems are used in biology, chemistry, and physics to model the interaction of spatially distributed species. Particularly of interest is the spatial replacement of one equilibrium state by another, depicted as traveling waves or fronts. Their profiles and traveling velocity depend on the nonlinearities in the reaction term and on spatial diffusion. If the reaction occurs at regularly spaced points, the velocities also depend on lattice structures and the orientation of the traveling front. Interestingly, there is a wide region of parameters where the speeds become zero and the fronts do not propagate. In this paper, we focus on systems with three stable coexisting equilibrium states that are described by the butterfly bifurcation and study to what extent the three possible 1D traveling fronts suffer from propagation failure. We demonstrate that discreteness of space affects the three fronts differently. Regions of propagation failure add a new layer of complexity to the butterfly diagram. The analysis is extended to planar fronts traveling through different orientations in regular 2D lattices. Both propagation failure and the existence of preferred orientations play a role in the transient and long-time evolution of 2D patterns.
Semiclassical spectrum of the Dirichlet–Pauli operator on an annulus
Authors: Lavigne Bon Enguerrand
Published: May 2022

This paper is devoted to the semiclassical analysis of the spectrum of the Dirichlet–Pauli operator on an annulus. We assume that the magnetic field is strictly positive and radial. We give an explicit asymptotic expansion at the first order of the lowest eigenvalues of this operator in the semiclassical limit. In particular, we exhibit the Aharonov–Bohm effect that has been revealed, for a constant magnetic field, in a recent paper by Helffer and Sundqvist.
Dielectric constant of aqueous solutions of proteins and organic polymers from molecular dynamics simulations
Authors: Liese Susanne , Schlaich Alexander , Netz Roland R.
Published: May 2022

The dielectric constant of water/oligomer mixtures, spanning the range from pure water to pure oligomeric melts, is investigated using molecular dynamics (MD) simulations. As prototypical water-soluble organic substances, we consider neutral poly-glycine, poly-ethylene glycol, and charged monomeric propionic acid. As the water content is reduced, the dielectric constant decreases but does not follow an ideal mixing behavior. The deviations from ideal mixing originate primarily in the non-linear relation between the oligomer mass fraction and collective polarization effects. We find that the dielectric constant is dominated by water polarization, even if the oligomer mass fraction exceeds 50%. By a double extrapolation of the MD simulation results to the limit of vanishing water fraction and to the limit of infinite oligomeric chain length, we estimate the orientational contribution to the dielectric constant of the pure polymeric melts. By this procedure, we obtain ɛ = 17 ± 2 for polyglycine and ɛ = 1 ± 0.3 for polyethylene glycol. The large difference is rationalized by polarization correlations of glycine units. Interestingly, we find constant temperature simulations to outperform replica exchange simulations in terms of equilibration speed.
The behavior of methane–water mixtures under elevated pressures from simulations using many-body potentials
Authors: Robinson Victor Naden , Ghosh Raja , Egan Colin K. , Riera Marc , Knight Christopher , Paesani Francesco , Hassanali Ali
Published: May 2022

Non-polarizable empirical potentials have been proven to be incapable of capturing the mixing of methane–water mixtures at elevated pressures. Although density functional theory-based ab initio simulations may circumvent this discrepancy, they are limited in terms of the relevant time and length scales associated with mixing phenomena. Here, we show that the many-body MB-nrg potential, designed to reproduce methane–water interactions with coupled cluster accuracy, successfully captures this phenomenon up to 3 GPa and 500 K with varying methane concentrations. Two-phase simulations and long time scales that are required to fully capture the mixing, affordable due to the speed and accuracy of the MBX software, are assessed. Constructing the methane–water equation of state across the phase diagram shows that the stable mixtures are denser than the sum of their parts at a given pressure and temperature. We find that many-body polarization plays a central role, enhancing the induced dipole moments of methane by 0.20 D during mixing under pressure. Overall, the mixed system adopts a denser state, which involves a significant enthalpic driving force as elucidated by a systematic many-body energy decomposition analysis.
Electrically controlled optical nonlinear effects in the hybrid opto-electromechanical system with the cross-Kerr effect
Authors: Zhou Ya-Fei , Qin Li-Guo , Huang Jie-Hui , Wang Li-Li , Tian Li-Jun , Wang Zhong-Yang , Gong Shang-Qing
Published: May 2022

We theoretically study the nonlinear optical phenomena including optical stability state and four-wave mixing (FWM) process in a hybrid opto-electromechanical system with the cross-Kerr (CK) effect. The hybrid system consists of an optomechanical cavity in which the cross-Kerr (CK) effect and Coulomb interaction are simultaneously introduced by the CK medium and the mechanical resonator capacitively coupling to an external circuit, respectively. The CK interaction induces a tristability behavior of the mean intracavity photon number, which can be modulated by the strength of the CK effect and electrically controlled by the voltage on the capacitor. In addition, we give the effects of the optomechanical, CK, and Coulomb coupling strengths on the FWM of the output field. The results show that the voltage can be employed to electrically engineer the optical nonlinear phenomena.
The rate of thermodynamic cost against adiabatic and nonadiabatic fluctuations of a single gene circuit in Drosophila embryos
Authors: Zhang Kun , Ramos Alexandre Ferreira , Wang Erkang , Wang Jin
Published: May 2022

We study the stochastic dynamics of the externally regulating gene circuit as an example of an eve-skipped gene stripe in the development of Drosophila. Three gene regulation regimes are considered: an adiabatic phase when the switching rate of the gene from the OFF to ON state is faster than the rate of mRNA degradation; a nonadiabatic phase when the switching rate from the OFF to ON state is slower than that of the mRNA degradation; and a bursting phase when the gene switching is fast and transcription is very fast, while the ON state probability is very low. We found that the rate of thermodynamic cost quantified by the entropy production rate can suppress the fluctuations of the gene circuit. A higher (lower) rate of thermodynamic cost leads to reduced (increased) fluctuations in the number of gene products in the adiabatic (nonadiabatic) regime. We also found that higher thermodynamic cost is often required to sustain the emergence of more gene states and, therefore, more heterogeneity coming from genetic mutations or epigenetics. We also study the stability of the gene state using the mean first passage time from one state to another. We found the monotonic decrease in time, i.e., in the stability of the state, in the transition from the nonadiabatic to adiabatic regimes. Therefore, as the higher rate of thermodynamic cost suppresses the fluctuations, higher stability requires higher thermodynamics cost to maintain.
Oscillatory behavior with fiber orientation in the flow–vorticity plane for fiber suspension under large amplitude oscillatory shear flow
Authors: Endo Hiroki , Hatsutomo Taichi , Sugihara Yukinobu , Takahashi Tsutomu
Published: May 2022

In fiber suspensions, fibers with three-dimensional orientation states are dramatically flow-oriented in the flow–flow gradient plane when the flow starts. In contrast, large strains are required for flow orientation in the flow–vorticity plane. Under oscillatory shear flow, when the strain amplitude is small, the flow orientation in the flow–vorticity plane is weakly induced, unlike that in the flow–flow gradient plane. The orientation in the flow–vorticity plane increases with the strain amplitude. At large strain amplitudes, fibers are oriented in the flow–flow gradient plane; thus, the rotational motion of fibers in the flow–flow gradient plane is dominant, i.e., fibers are almost flow-oriented in the flow–vorticity plane. However, contributions of the oscillatory behavior of fiber orientation in the flow–flow gradient and flow–vorticity planes to complex viscosity are unclear. In this study, the objective is to determine the contributions of fiber orientation in each plane to complex viscosity with the two initial orientation states (random and flow-oriented states) for the strain sweep test. The two initial orientation states were controlled by manipulating the upper disk of the parallel disk flow path. The initial random state was induced by sliding the upper disk up and down. The initial flow-oriented state was induced by rotating the upper plate. Furthermore, phase transition behaviors from the random to flow-oriented state in the flow–vorticity plane with increasing strain amplitude were qualitatively estimated as the orientation angle via visualization. Consequently, when the initial orientation was random, the fibers gradually vibrated in a medium strain amplitude region, and complex viscosity was higher than that of the initial flow-oriented state. In the conclusion, we divided the complex viscosity behavior of the strain sweep test into five strain amplitude regions and clarified the dominant orientation state in each region. It is conceivable that this result will help in understanding the relationship between fiber orientation and dynamic viscoelastic properties of fiber suspension like fiber-reinforced thermoplastics.
Mechanical investigations of free-standing SiN membranes patterned with one-dimensional photonic crystal structures
Authors: Akbar Darki Ali , Vinther Nielsen Robin , Vinge Nygaard Jens , Dantan Aurélien
Published: May 2022

A detailed investigation of the structural and vibrational properties of various prestressed silicon nitride membranes patterned with one-dimensional photonic crystal structures is presented. The tensile stress related deformation of the structure in the vicinity of the patterned area is determined by atomic force microscopy scans, while the resonance frequencies and quality factors of the out-of-plane membrane vibrations are measured using optical interferometry. We show that these noninvasive measurements, combined with the results of finite element simulations, provide accurate information on the tensile stress, the elasticity modulus, and the density of these nanostructured thin films. The obtained results are interesting in two ways: first, they show that such highly reflective thin membranes already exploited in various photonics applications possess high-mechanical quality, which also makes them attractive for optomechanics and sensing applications. Second, they represent a nondestructive method to determine key material parameters, which can be applicable to a broad range of fragile nanostructured thin films.
An optimal control method to compute the most likely transition path for stochastic dynamical systems with jumps
Authors: Wei Wei , Gao Ting , Chen Xiaoli , Duan Jinqiao
Published: May 2022

Many complex real world phenomena exhibit abrupt, intermittent, or jumping behaviors, which are more suitable to be described by stochastic differential equations under non-Gaussian Lévy noise. Among these complex phenomena, the most likely transition paths between metastable states are important since these rare events may have a high impact in certain scenarios. Based on the large deviation principle, the most likely transition path could be treated as the minimizer of the rate function upon paths that connect two points. One of the challenges to calculate the most likely transition path for stochastic dynamical systems under non-Gaussian Lévy noise is that the associated rate function cannot be explicitly expressed by paths. For this reason, we formulate an optimal control problem to obtain the optimal state as the most likely transition path. We then develop a neural network method to solve this issue. Several experiments are investigated for both Gaussian and non-Gaussian cases.
Thermal activation of low-density Ga implanted in Ge
Authors: Foster Natalie D. , Miller Andrew J. , Hutchins-Delgado Troy A. , Smyth Christopher M. , Wanke Michael C. , Lu Tzu-Ming , Luhman Dwight R.
Published: May 2022

The nuclear spins of low-density implanted Ga atoms in Ge are interesting candidates for solid state-based qubits. To date, activation studies of implanted Ga in Ge have focused on high densities. Here, we extend activation studies into the low-density regime. We use spreading resistance profiling and secondary ion mass spectrometry to derive electrical activation of Ga ions implanted into Ge as a function of the rapid thermal anneal temperature and implant density. We show that for our implant conditions, the activation is best for anneal temperatures between 400 and 650 °C with a maximum activation of 69% at the highest fluence. Below 400 °C, remaining implant damage results in defects that act as superfluous carriers, and above 650 °C, surface roughening and loss of Ga ions are observed. The activation increased monotonically from 10% to 69% as the implant fluence increased from 6×1010 to 6×1012 cm−2. The results provide thermal anneal conditions to be used for initial studies of using low-density Ga atoms in Ge as nuclear spin qubits.
Universal time-domain Prony fitting decomposition for optimized hierarchical quantum master equations
Authors: Chen Zi-Hao , Wang Yao , Zheng Xiao , Xu Rui-Xue , Yan YiJing
Published: May 2022

In this Communication, we propose the time-domain Prony fitting decomposition (t-PFD) as an accurate and efficient exponential series method, applicable to arbitrary bath correlation functions. The resulting numerical efficiency of hierarchical equations of motion (HEOM) formalism is greatly optimized, especially in low temperature regimes that would be inaccessible with other methods. For demonstration, we calibrate the present t-PFD against the celebrated Padé spectrum decomposition method, followed by converged HEOM evaluations on the single-impurity Anderson model system.
Are point of management assays relevant for food safety in the poultry industries?
Authors: Templeton J. M. , Botella J. R. , Blackall P. J.
Published: May 2022

The current pandemic has ensured considerable attention has been paid to the role of the approach termed ‘Point of Care’ diagnostics. Indeed, the term ‘RAT’ (Rapid Antigen Test) and RAT hunting now have totally different meaning to that widely understood before 2020. In the veterinary field, including food safety, the term used for these types of rapid in situ assays is ‘Point of Management’ (POM) assays. In this article, we describe our recent research on low cost, low technology, in-house style POM assays in the field of food safety as applied to the poultry industries. We then discuss what are the advantages and disadvantages of these low cost, low technology POM assays.
Spatiotemporal dynamics of odor representations in the human brain revealed by EEG decoding
Authors: Kato Mugihiko , Okumura Toshiki , Tsubo Yasuhiro , Honda Junya , Sugiyama Masashi , Touhara Kazushige , Okamoto Masako
Published: May 2022

Significance

To elucidate when and where in the brain different aspects of odor perception emerge, we decoded odors from an electroencephalogram and associated the results with perception and source activities. The odor information was decoded 100 ms after odor onset at the earliest, with its signal sources estimated in and around the olfactory areas. The neural representation of odor unpleasantness emerged 300 ms after odor onset, followed by pleasantness and perceived quality at 500 ms. During this time, brain regions representing odor information spread rapidly from the olfactory areas to regions associated with emotional, semantic, and memory processing. The results suggested that odor perception emerges through computations in these areas, with different perceptual aspects having different spatiotemporal dynamics.
An ancient founder mutation located betweenROBO1andROBO2is responsible for increased microtia risk in Amerindigenous populations
Authors: Quiat Daniel , Kim Seong Won , Zhang Qi , Morton Sarah U. , Pereira Alexandre C. , DePalma Steven R. , Willcox Jon A. L. , McDonough Barbara , DeLaughter Daniel M. , Gorham Joshua M. , Curran Justin J. , Tumblin Melissa , Nicolau Yamileth , Artunduaga Maria A. , Quintanilla-Dieck Lourdes , Osorno Gabriel , Serrano Luis , Hamdan Usama , Eavey Roland D. , Seidman Christine E. , Seidman J. G.
Published: May 2022

Significance

The genetic basis of isolated microtia, a congenital abnormality of the external ear, is poorly understood. Indigenous American (Amerindigenous) populations have the highest reported incidence of microtia. Here, we use whole genome sequencing to study microtia in Latin American families and identify a common microtia risk allele that is enriched among individuals with Amerindigenous ancestry. This allele is located in a regulatory region governing the expression of Roundabout 1 (ROBO1) and Roundabout 2 (ROBO2) in induced pluripotent stem cell–derived neural crest cells and is associated with a complex repeat sequence. These results identify a shared genetic basis for isolated microtia and other craniofacial abnormalities and account for, at least in part, the increased incidence of microtia in Amerindigenous populations.
Revisiting the probe and enclosure methods
Authors: Ikehata Masaru
Published: May 2022

This paper is concerned with reconstruction issue of inverse obstacle problems governed by partial differential equations and consists of two parts. (i) The first part considers the foundation of the probe and enclosure methods for an impenetrable obstacle embedded in a medium governed by the stationary Schrödinger equation. Under a general framework, some natural estimates for a quantity computed from a pair of the Dirichlet and Neumann data on the outer surface of the body occupied by the medium are given. The estimates enables us to derive almost immediately the necessary asymptotic behaviour of indicator functions for both methods. (ii) The second one considers the realization of the enclosure method for a penetrable obstacle embedded in an absorbing medium governed by the stationary Schrödinger equation. The unknown obstacle considered here is modeled by a perturbation term added to the background complex-valued L
∞-potential. Under a jump condition on the term across the boundary of the obstacle and some kind of regularity for the obstacle surface including Lipschitz one as a special case, the enclosure method using infinitely many pairs of the Dirichlet and Neumann data is established.
Cu9S5 nanoparticles encapsulated in N, S co-doped carbon nanofibers as anodes for high-performance lithium-ion and sodium-ion batteries
Authors: Lu Rou , Zhou Shuang , Chai Simin , Zhong Yue , Zhang Haomiao , Chen Jing , Chang Zhi , Pan Anqiang
Published: May 2022

Copper sulfides (Cu
x
S) have gained increasing attention for using as anodes of rechargeable batteries owing to their high theoretical capacity and good electron conductivity. However, the structure instability and sluggish reaction kinetics seriously deteriorate their electrochemical performance. To tackle with these inherent drawbacks, an elaborate hierarchical architecture composed of N, S co-doped carbon nanofibers and well-dispersed Cu9S5 nanocrystallines (Cu9S5/CNFs) was fabricated. After sulfurization, the Cu9S5 nanoparticles that uniformly distributed on the CNFs surface are well-encapsulated inside the graphitic carbon shell. For the hierarchical Cu9S5/CNFs, the ion diffusion pathways can be shortened by the nano-sized Cu9S5 while the graphitized carbon shell can provide rapid electron transfer as well as accommodate the volume variation of Cu9S5 upon cycling. Additionally, the heteroatom within CNFs can provide abundant edges and defects for adsorbing lithium/sodium ions, thus boosting the reaction kinetics of batteries. Benefiting from all of these merits, the Cu9S5/CNFs composite obtained under 600 °C (Cu9S5/CNFs-600) used as anode for lithium-ion batteries (LIBs) demonstrates high specific capacity (709.2 mAh g−1 at 0.1 A g−1 after 100 cycles), good rate performance (509.1 mAh g−1 at 2 A g−1) and excellent durability (540.2 mAh g−1 at 1 A g−1 after 800 cycles with a ultrahigh capacity retention of 92.5%). And it also exhibits stable cycling performance (with a capacity retention of 90.5% after 1500 cycles at 1 A g−1) and excellent rate performance in sodium-ion batteries (SIBs). This work provides a promising strategy to prepare high-performance copper sulfides-based anode materials for LIBs and SIBs.
Weyl semimetal states in transition metal monochalcogenide superlattices AX/BX (A, B = Cr, Mo, W, A ≠ B; X = Se, Te)
Authors: Zhao X M , Li Y Z , Zhao L L , Dai T A , Zhong J X , Meng L J
Published: May 2022

Based on first-principles calculations and the Wannier-function-based tight-binding method, we investigate the topological electronic properties of designed noncentrosymmetric transition metal monochalcogenide superlattices AX/BX (A, B = Cr, Mo, W, A ≠ B; X = Se, Te). Here, we mainly consider time-reversal symmetry (TRS) MoTe/WTe and MoSe/WSe and TRS broken CrTe/WTe and CrTe/MoTe, which are the Weyl and magnetic Weyl semimetals, respectively. The considered systems are nodal line semimetals with nodal lines on three mirror planes of the Brillouin zone of hexagonal lattice in the absence of spin–orbit coupling (SOC). When considering the SOC, each nodal line opens a gap except for some pairs of Weyl points (WPs) on the kz
≠ 0 planes and the number of WPs is material-dependent. We identify the termination-dependent Fermi arc connection patterns on the (001) and (00

1
ˉ

) surfaces for four Weyl semimetal superlattices AX/BX. These results provide a theoretical basis to realize the possible applications of these superlattice materials in future topological electronic devices.
Zeeman and laser site selective spectroscopy of C1 point group symmetry Sm3+ centres in Y2SiO5: a parametrized crystal-field analysis for the 4f
5 configuration
Authors: Jobbitt N L , Wells J-P R , Reid M F
Published: May 2022

Parametrized crystal-field analyses are presented for both the six and seven fold coordinated, C1 symmetry Sm3+ centres in Y2SiO5, based on extensive spectroscopic data spanning the infrared to optical regions. Laser site-selective excitation and fluorescence spectroscopy as well as Zeeman absorption spectroscopy performed along multiple crystallographic directions has been utilized, in addition to previously determined g tensors for the 6H5/2Z1 and 4G5/2A1 states. The resultant analyses give good approximation to the experimental energy levels and magnetic splittings, yielding crystal-field parameters consistent with the few other lanthanide ions for which such analyses are available.
Effect of Ce substitution on the local magnetic ordering and phonon instabilities in antiferromagnetic DyCrO3 perovskites
Authors: Das S , Dokala R K , Weise B , Medwal R , Rawat R S , Mishra P K , Thota S
Published: May 2022

A detailed crystal structure analysis, temperature and field dependence of magnetic characteristics and phonon instabilities for different compositions (0.1 ⩽ x ⩽ 0.5) of Dy1−x
Ce
x
CrO3 solid-solutions have been reported. All the investigated compounds exhibit distorted orthorhombic crystal structure with a distortion factor of d
Oct/d
Cell ∼ 6 × 10−3/3.5 ppm (for x ∼ 0.2) for Pbnm space group that follows Vegard’s law. The bonds between apical oxygen atoms (OA1) and Cr atoms stand more rigidly in comparison with the basal oxygen atoms (OB1/OB2) resulting the octahedral distortion and thereby causing the changes in phonon modes. The CrO6 octahedral tilt angle θ rotates with respect to the Miller pseudocubic axis [101] which varies from 10.36° (x = 0.1) to 12.25° (x = 0.5) and significantly influences the Ag(5) phonon stability by 3% for a change in A-site mean radius from 1.095 Å to 1.141 Å for x = 0.1 and 0.5, respectively. From the magnetization measurements we find that these series of compositions exhibit canted antiferromagnetic (AFM) ordering with Néel temperature,

T

N

1

that increases from 151.8 K (x = 0.1) to 162 K (x = 0.5) which also manifests as a significant reduction in the magneto-crystalline anisotropy (H
K ∼ 2.58 kOe → 2.07 kOe, K
1 ∼ 36.47 J m−3 → 18.97 J m−3) while maintaining the stable Γ4(G

x
, A

y
, F

z
) AFM configuration. Both Dzyaloshinskii–Moriya interaction method and modified Curie–Weiss law are employed to analyse the inverse paramagnetic susceptibility, χ
−1(T >

T

N

1

). Further, we have evaluated the symmetric (J
S) and antisymmetric exchange (D
AS) constants, which show progressively increasing trend (J
S → 10.08 K to 11.18 K and D
AS → 1.24 K to 1.73 K) with the incorporation of Ce inside the perovskite lattice. Furthermore, the role of Ce substitution on the low-temperature spin reorientation transition (T
SR ∼ 3.5 K → 16.8 K pertaining to the Γ25 phase configuration) and emergence of

Γ

2

(

F

x

,

C

y

,

G

z

;

F

x

R

,

C

y

R

)

weak-FM phase between 31 K and 45.5 K are discussed in consonance with the phonon spectra.
Enhanced seeded region growing algorithm and its application in signal decomposition
Authors: Ma Chaoyong , Ma Xingjie , Xu Yonggang , Xiang Ling , Zhang Kun
Published: May 2022

The components in an engineering signal may overlap in the frequency domain, which causes great inconvenience and even errors in traditional one-dimensional signal processing methods. To identify and extract components in the signal from the time-frequency domain, this paper proposes a time-frequency domain signal decomposition method based on enhanced seeded region growing (ESRG). This paper extends the seeded region growing method to adaptive recognition of target regions in the time-frequency representation and divides the time-frequency representation into several time-frequency components. ESRG can reduce the influence of noise, expand the self-adaptability of time-frequency decomposition and avoid errors caused by manually setting the growth point and threshold. The results of the numerical verification and decomposition of bat echo signals show that this method can accurately decompose multi-component non-stationary signals. The decomposition results of rotor fault and rolling bearing fault signals show that this method can be successfully applied to fault diagnosis.
An accurate and reliable positioning methodology for land vehicles in tunnels based on UWB/INS integration
Authors: Kong Xin , Li Xu , Song Xiang , Tian Yuan , Kong Dong
Published: May 2022

At present, the global navigation satellite system (GNSS) is the most widely used technology in the field of vehicle navigation and positioning. However, due to satellite signal blocking, it can be challenging to obtain precise and reliable vehicle positions in completely GNSS-denied environments. In this paper, a positioning strategy utilizing ultra-wide band (UWB) and a low-cost MEMS inertial navigation system (INS) is proposed, aimed at tracking vehicles in typical GNSS-denied scenarios. UWB tech has potential for high-precision ranging due to its strong penetration ability. However, non-line-of-sight (NLOS) propagation still has a high occurrence in typical traffic scenarios due to the fact that the direct path between the radio transmitter and the radio receiver is obstructed. Therefore, a two-step NLOS error mitigation method is proposed to deal with the abnormal measurements of UWB in tunnels. First, a state-of-the-art probabilistic factor graph model is proposed to estimate the vehicle’s position information based on UWB range measurements instead of excluding the NLOS reception. Then, a residual weighting algorithm is employed during UWB/INS loosely coupled integration to further mitigate the NLOS error. Finally, the performance of the proposed methodology is evaluated through experiments. Experiments conducted in the typical NLOS environment of Nanjing show that the proposed method can achieve higher positioning accuracy when compared with the conventional UWB/INS integration.
First-principles simulation of neutral and charged oxygen vacancies in m-ZrO2: an origin of filamentary type resistive switching
Authors: Chaurasiya Rajneesh , Lin Pei-En , Lyu Cheng-Han , Chen Kuan-Ting , Shih Li-Chung , Chen Jen-Sue
Published: May 2022

Metal oxide ZrO2 has been widely explored for resistive switching application due to excellent properties like high ON/OFF ratio, superior data retention, and low operating voltage. However, the conduction mechanism at the atomistic level is still under debate. Therefore, we have performed comprehensive insights into the role of neutral and charged oxygen vacancies in conduction filament (CF) formation and rupture, which are demonstrated using the atomistic simulation based on density functional theory (DFT). Formation energy demonstrated that the fourfold coordinated oxygen vacancy is more stable. In addition, the electronic properties of the defect included supercell confirm the improvement in electrical conductivity due to the presence of additional energy states near Fermi energy. The CF formation and rupture using threefold and fourfold oxygen vacancies are demonstrated through cohesive energy, electron localization function, and band structure. Cohesive energy analysis confirms the cohesive nature of neutral oxygen vacancies while the isolated behavior for +2 charged oxygen vacancies in the CF. In addition, nudged elastic band calculation is also performed to analyze the oxygen vacancy diffusion energy under different paths. Moreover, we have computed the diffusion coefficient and drift velocity of oxygen vacancies to understand the CF. This DFT study described detailed insight into filamentary type resistive switching observed in the experimentally fabricated device. Therefore, this fundamental study provides the platform to explore the switching mechanism of other oxide materials used for memristor device application.
Experimental study of non-inductive current start-up using electron cyclotron wave on EXL-50 spherical torus
Authors: Wang Mingyuan , Guo Dong , Shi Yuejiang , Chen Bo , Liu Bing , Song Shaodong , Zhao Xin , Song Yunyang , Liu Wenjun , Guan Yupeng , Banerjee Debabrata , Li Songjian , Sun Tiantian , Li Yingying , Tian Xiaomin , Zhu Yubao , Song Xianming , Dong Jiaqi , Yuan Baoshan , Martin Peng Y-K
Published: May 2022

Although experiments have demonstrated a feasibility of the electron-cyclotron-wave (ECW) non-inductive current start-up, the physical mechanism of the current start-up remains unclear, particularly the role of the preferential confinement of collisionless tail electron currents (

j

TPC

)

and vertical charge-separation currents (

j

VTF

)

. Therefore,

j

TPC

and

j

VTF

were observed using limiter probes during the ECW non-inductive current start-up on an ENN XunLong-50 (EXL-50) spherical torus to understand the significance of these values. It was found that

j

TPC

increased and

j

VTF

decreased during start-up, indicating a dominant role played by

j

TPC

in this process. Furthermore, it was found that the product of the gas pressure and vertical magnetic field has a limit for the ECW non-inductive current start-up. Finally, we found that the ECW non-inductive current start-up can be realized only for sufficiently low vertical fields and gas pressures in EXL-50.
Foundations of plasma surface functionalization of polymers for industrial and biological applications
Authors: Booth Jean-Paul , Mozetič Miran , Nikiforov Anton , Oehr Christian
Published: May 2022

Polymer materials are widely employed in many fields due to the ease with which they can be formed into complex shapes, their versatile mechanical properties, light weight, and low cost. However, many applications are hindered by the chemical compatibility of polymer surfaces, which are generally hydrophobic and bond poorly to other media such as paints, glues, metals and biological media. While polymer surfaces can be treated by wet chemical processes, the aggressive reagents employed are detrimental to the environment, limiting the range of modifications that can be achieved by this route. Plasma functionalization is an attractive alternative, offering great versatility in the processed surface characteristics, and generally using environmentally benign compounds such as rare gases, oxygen and nitrogen, as well as very small quantities of organic precursors. Since the modified surfaces are only a few monolayers thick, these processes are extremely rapid and low in cost. The first industrial process to be developed was plasma oxidation, which increases the surface energy of the polymer, improving the adhesion of paint, glue and metal to the component. Plasma oxidation can be achieved using both low-pressure and atmospheric pressure (APP) discharges. Subsequently, many other processes have emerged, allowing other functional groups to be grafted, including amines, hydroxyl and carboxylic acid groups. Plasma polymerization, starting from gaseous monomers, allows a whole new family of surface chemistries to be created. These processes have many exciting applications in the biomedical field due to the control they give on biocompatibility and selective interaction with living cells. This article will present the fundamentals of plasma interactions with polymers, the plasma devices employed (both at low-pressure and at APP) with their advantages and drawbacks, and a survey of current and future applications.
Monte Carlo simulations of spin transport in nanoscale

In0.7Ga0.3As

transistors: temperature and size effects
Authors: Thorpe B , Schirmer S , Kalna K
Published: May 2022

Spin-based metal-oxide-semiconductor field-effect transistors (MOSFETs) with a high-mobility III-V channel are studied using self-consistent quantum corrected ensemble Monte Carlo device simulations of charge and spin transport. The simulations including spin–orbit coupling mechanisms (Dresselhaus and Rashba coupling) examine the electron spin transport in the 25 nm gate length

I

n

0.7

G

a

0.3

A
s

MOSFET. The transistor lateral dimensions (the gate length, the source-to-gate, and the gate-to-drain spacers) are increased to investigate the spin-dependent drain current modulation induced by the gate from room temperature of 300 K down to 77 K. This modulation increases with increasing temperature due to increased Rashba coupling. Finally, an increase of up to 20 nm in the gate length, source-to-gate, or the gate-to-drain spacers increases the spin polarization and enhances the spin-dependent drain current modulation at the drain due to polarization-refocusing effects.
Theoretical analysis of atomic parameters of Sm-like and Nd-like W ions in soft x-ray region
Authors: Singh Narendra , Aggarwal Sunny , Goyal Arun
Published: May 2022

We calculated atomic data such as energy levels, transition wavelengths, oscillator strengths and transition rates for Sm-like and Nd-like W ions. We employed flexible atomic code (FAC) in our computations. We computed fine structure levels of configurations 4f125s2, 4f125s5p and 4f135s for Nd-like W and configurations 4f145s2, 4f135s25p and 4f125s25p2 for Sm-like W. We have provided transition data of electric dipole (E1) transitions and magnetic quadrupole (M2) transitions for transition 4f125s2—4f125s5p and magnetic dipole (M1) and electric quadrupole (E2) transition data for transition 4f145s2 − 4f125s25p2. We also found that spectral lines of these transitions in Sm and Nd-like W ion spectra lie in soft x-ray (SXR) region. We compared transition data of Nd-like W and excitation energies of Sm-like W ions with available theoretical and experimental results. We also discussed the effect of configuration interaction on atomic data of Nd-like W and excitation energies of Sm-like W by systematically increasing the number of configurations.
Rapidity distribution within Landau hydrodynamical model and EPOS event-generator at AGS, SPS, and RHIC energies
Authors: Rahman R M Abdel , Tawfik Abdel Nasser , El-Bakry Mahmoud Y , Habashy D M , Hanafy Mahmoud
Published: May 2022

The rapidity distribution of well-identified particles such as pions, kaons, protons and their antiparticles measured in AGS, SPS, and BRAHMS experiments (Au+Au collisions), at various energies spanning from higher energies

s

NN

= 200 down to lower energies 2 GeV, are compared with that obtained from huge statistical ensembles of 100, 000 events generated from the Cosmic Ray Monte Carlo (CRMC) EPOS event-generator. All these data are then compared to the results calculated in the frame work of Landau hydrodynamical model. The EPOS event-generator can describe the experimental data of the rapidity distribution for all mentioned particles at all considered energies. This leads to use the EPOS event-generator to produce the rapidity distribution for various particles at energies where there are no experimental data yet to compare with. Such a prediction might serve as an input for future experiments such as FAIR and NICA for instance. A successful comparison between the Landau hydrodynamical approach and the computational CRMC EPOS 1.99 model in describing the rapidity distribution for the mentioned particles is shown in the presence of the experimental data. We conclude that the Landau hydrodynamical model is capable of describing both experimental data and EPOS 1.99 event-generator results, and they are in a good agreement.
A broadband tunable asymmetric transmission structure design
Authors: Wang Wei , Xuan Chengming , Qi Wuchao , Yang Zhe , Xu Weikai
Published: May 2022

In this paper, we design a tunable asymmetric transmission structure consisting of a one-dimensional phononic crystal metastructure and a simple mass oscillator metasurface. By reasonably adjusting the width of the supercell in the metasurface, transmission control of the flexural wave can be achieved. According to the generalized Snell’s law, anomalous refraction occurs when the flexural wave is obliquely incident, while total reflection will occur when the flexural wave is vertically incident. The one-dimensional phononic crystal metastructure can be used to deflect the perpendicularly incident flexural wave. In combination with the metasurface, the asymmetric transmission of flexural waves over a quite wide frequency range can be achieved. The designed asymmetric transmission structure has both tunability and broadband capability. Adjusting the distance of the mass oscillators in the metastructure and the phase distribution of the metasurface can realize the modulation of refraction angles, while increasing or decreasing the number of mass oscillators can further expand the operating frequency domain of the tunable asymmetric transmission structure. Numerical results show that the proposed structure can achieve asymmetric transmission of flexural waves in the frequency domain of 13–25 kHz or even wider.
Spitzer Publication Statistics
Authors: Scire E. , Rebull Luisa , Laine Seppo
Published: May 2022

We present statistics on the number of refereed astronomy journal articles that used data from NASA’s Spitzer Space Telescope through the end of the calendar year 2020. We discuss the various types of science programs and science categories that were used to collect data during the mission and discuss how operational changes brought on by the depletion of cryogen in 2009 May, including the resulting budget cuts, impacted the publication rate. The post-cryogenic (warm) mission produced fewer papers than the cryogenic mission, but the percentage of the exposure time published did not appreciably change between the warm and cryogenic missions. This was mostly because in the warm mission the length of observations increased, so that each warm paper on average uses more data than the cryogenic papers. We also discuss the speed of publication, archival usage, and the tremendous efficacy of the Legacy and Exploration Science programs (large, coherent investigations), including the value of having well-advertised enhanced data products hosted in centralized archives. We also identify the observations that have been published the largest number of times, and sort them by a variety of metrics (including program type, instrument used, and observation length). Data that have the highest reuse rates in publications were taken early in the Spitzer mission, or belong to one of the large surveys (large either in number of objects, in number of hours observed, or in area covered on the sky). We also assess how often authors have cited the Spitzer fundamental papers or have correctly referenced the Spitzer data they used, finding that as many as 40% of papers have failed to cite the papers, and 15% have made it impossible to identify the data they used.
Ultra-wide Bandwidth Observations of 19 Pulsars with Parkes Telescope
Authors: Zhou Zu-Rong , Wang Jing-Bo , Wang Na , Hobbs George , Wang Shuang-Qiang
Published: May 2022

Flux densities are basic observation parameters to describe pulsars. In the most updated pulsar catalog, 24% of the listed radio pulsars have no flux density measurement at any frequency. Here, we report the first flux density measurements, spectral indices, pulse profiles, and correlations of the spectral index with pulsar parameters for 19 pulsars employing the Ultra-Wideband Low receiver system installed on the Parkes radio telescope. The results for spectral indices of 17 pulsars are in the range between −0.6 and −3.10. The polarization profiles of thirteen pulsars are shown. There is a moderate correlation between the spectral index and spin frequency. For most pulsars detected, the signal-to-noise ratio of pulse profile is not high, so DM, Faraday rotation measure, and polarization cannot be determined precisely. Twenty-nine pulsars were not detected in our observations. We discuss the possible explanations for why these pulsars were not detected.
Toward efficient runs of nonlinear gyrokinetic simulations assisted by a convolutional neural network model recognizing wavenumber-space images
Authors: Narita E. , Honda M. , Maeyama S. , Watanabe T.-H.
Published: May 2022

A neural-network based innovative model recognizing the wavenumber space images has been developed to accurately forecast when the saturation of turbulent heat fluxes commences, i.e., the saturation time, in nonlinear gyrokinetic simulations. The wavenumber space images of the perturbed distribution function are focused on, which better represent the characteristics of turbulence. The model exploiting the state-of-the-art convolutional neural network model is capable of detecting minuscule differences between the images. Once the wavenumber space image is fed into the developed model, it can quickly and almost perfectly classify which phase of the turbulence evolution in nonlinear gyrokinetic simulations the image is in: the linearly and nonlinearly growing phases and the saturation phase. It can also predict the simulation time at which the image was processed with significantly high accuracy. The model enables us to forecast the saturation time of the gyrokinetic simulation in question by feeding an image at an early stage of the simulation and receiving the degree of progress toward the saturation. The ability of the model makes it possible to easily search out a desirable initial condition that rapidly conducts the simulation to a saturation phase. Such a pre-prediction model is important for running long time simulations on a large scale supercomputer like Fugaku in view of the efficient use of computational resources. In order to improve the predictive capability for the simulation that is going to be performed, several prediction models are trained by data with different major instabilities. The best predictor is selected to be in use based on the result of the pre-performed linear stability calculation with low computational cost.
Error estimates for discrete generalized FEMs with locally optimal spectral approximations
Authors: Ma Chupeng , Scheichl Robert
Published: May 2022

This paper is concerned with error estimates of the fully discrete generalized finite element method (GFEM) with optimal local approximation spaces for solving elliptic problems with heterogeneous coefficients. The local approximation spaces are constructed using eigenvectors of local eigenvalue problems solved by the finite element method on some sufficiently fine mesh with mesh size

h
h

. The error bound of the discrete GFEM approximation is proved to converge as

h
→
0

h\rightarrow 0

towards that of the continuous GFEM approximation, which was shown to decay nearly exponentially in previous works. Moreover, even for fixed mesh size

h
h

, a nearly exponential rate of convergence of the local approximation errors with respect to the dimension of the local spaces is established. An efficient and accurate method for solving the discrete eigenvalue problems is proposed by incorporating the discrete

A
A

-harmonic constraint directly into the eigensolver. Numerical experiments are carried out to confirm the theoretical results and to demonstrate the effectiveness of the method.
The structure of higher sumsets
Authors: Lev Vsevolod
Published: May 2022

Merging together a result of Nathanson from the early 70s and a recent result of Granville and Walker, we show that for any finite set

A
A

of integers with

min
(
A
)
=
0

\min (A)=0

and

gcd
(
A
)
=
1

\gcd (A)=1

there exist two sets, the “head” and the “tail”, such that if

m
≥
max
(
A
)
−

|

A

|

+
2

m\ge \max (A)-|A|+2

, then the

m
m

-fold sumset

m
A

mA

consists of the union of the head, the appropriately shifted tail, and a long block of consecutive integers separating them. We give sharp estimates for the length of the block, and find all those sets

A
A

for which the bound

max
(
A
)
−

|

A

|

+
2

\max (A)-|A|+2

cannot be substantially improved.
A sharpened inequality for twisted convolution
Authors: O’Neill Kevin
Published: May 2022

Consider the trilinear form for twisted convolution on

R

2
d

\mathbb {R}^{2d}

:
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="script upper T Subscript t Baseline left-parenthesis bold f right-parenthesis colon-equal double-integral f 1 left-parenthesis x right-parenthesis f 2 left-parenthesis y right-parenthesis f 3 left-parenthesis x plus y right-parenthesis e Superscript i t sigma left-parenthesis x comma y right-parenthesis Baseline d x d y comma">

T

t

(

f

)
≔
∬

f
1

(
x
)

f
2

(
y
)

f
3

(
x
+
y
)

e

i
t
σ
(
x
,
y
)

d
x
d
y
,

\begin{equation*} \mathcal {T}_t(\mathbf {f})≔\iint f_1(x)f_2(y)f_3(x+y)e^{it\sigma (x,y)}dxdy, \end{equation*}

where

σ
\sigma

is a symplectic form and

t
t

is a real-valued parameter. It is known that in the case

t
≠
0

t\neq 0

the optimal constant for twisted convolution is the same as that for convolution, though no extremizers exist. Expanding about the manifold of triples of maximizers and

t
=
0

t=0

we prove a sharpened inequality for twisted convolution with an arbitrary antisymmetric form in place of

σ
\sigma

.
Equivariant degenerations of plane curve orbits
Authors: Lee Mitchell , Patel Anand , Tseng Dennis
Published: May 2022

In a series of papers, Aluffi and Faber computed the degree of the

G

L
3

GL_3

-orbit closure of an arbitrary plane curve. We attempt to generalize this to the equivariant setting by studying how orbits degenerate under some natural specializations, yielding a fairly complete picture in the case of plane quartics.