bluuebunny/crossref_metadata_2025 huggingface dataset:
The modulation of electrothermal distribution by square spiral kirigami structure in graphite paper
Authors: Jingye Gao , Yinglin Qin , Bojun Yang , Chang Wang , Anzuo Qin , Si Xiao , Jun He
Published: December 2022

A square spiral incision was introduced into a 15 × 15 cm regular quadrilateral conductive film to study the modulation of electrothermal distribution by kirigami structure. Based on the simulation of finite element method, the transition from thermal focusing to thermal defocusing could be achieved by increasing the length of connection between adjacent modules. The effective electrothermal area can be increased by nearly two times through increasing the length increment of the notch length between adjacent modules. The maximum temperature was decreased from 254 °C to 44 °C, and the temperature difference was adjusted from 76 °C to 4 °C by increasing the number of kirigami module. Through the contact temperature measurement experiment on graphite paper kirigami structure, the trends could be verified. By creating an equivalent circuit model and considering the influence of heat conduction, the peak temperature at the center of the structure and the decrease of the overall temperature could be explained. By deriving the relationship between the temperature of conductive film of kirigami structure with time and position, the electrothermal characteristics of previously reported graphene kirigami structure could be predicted.
Charge transport characteristic and charge stability enhancement mechanism of polyimide aerogel as an ultralight weight electret
Authors: Song Bo , Ren Ming , Hu Yizhuo , Wang Yue , Liu Yujie , Dong Ming
Published: December 2022

In this study, polyimide aerogel (PIA) is applied as an ultralight-weight and thermally stable electret material, meanwhile its charge transport characteristic and charge stability enhancement mechanism are investigated. It is found that PIA can exhibit excellent electret properties at 120 °C after corona charging at room temperature, and its charge stability acquires further promotion after charging at elevated temperatures or heat treatment, which far exceeds conventional polyimide-based electrets. Further research indicates that the outstanding charge retention characteristics of PIA originate from the enhanced local defect density, fast retrapping effect, weakened internal electric field by dipole polarization, and prolonged conduction path, which are inextricably linked to its porous structure. In addition, the high gas breakdown strength in the pores of PIA effectively limits the breakdown induced conductivity, thereby ensuring high space charge density and large piezoelectric response of PIA electrets. Considering the extremely low density and inherently excellent properties of polyimide substances, PIA may have promising prospects as an electret in the lightweight sensing and energy conversion devices at elevated temperatures.
Charged elastic rings: deformation and dynamics
Authors: Yao Zhenwei
Published: December 2022

We report the counter-intuitive instability of charged elastic rings, and the persistence of sinusoidal deformations in the lowest-energy configurations by the combination of high-precision numerical simulations and analytical perturbation calculation. We also study the dynamical evolution of the charged ring under random disturbance, and reveal the modulation of the dominant frequencies by the electrostatic force. The purely mechanical analysis of the classical ring system presented in this work yields insights into the subtlety of long-range forces in the organization and dynamics of matter.
High pressure phase transition and strength estimate in polycrystalline alumina during laser-driven shock compression
Authors: Hari Anirudh , Hari Rohit , Heighway Patrick G , Smith Raymond F , Duffy Thomas S , Sims Melissa , Singh Saransh , Fratanduono Dayne E , Bolme Cynthia A , Gleason Arianna E , Coppari Federica , Lee Hae Ja , Granados Eduardo , Heimann Philip , Eggert Jon H , Wicks June K
Published: December 2022

Alumina (Al2O3) is an important ceramic material notable for its compressive strength and hardness. It represents one of the major oxide components of the Earth’s mantle. Static compression experiments have reported evidence for phase transformations from the trigonal α-corundum phase to the orthorhombic Rh2O3(II)-type structure at ∼90 GPa, and then to the post-perovskite structure at ∼130 GPa, but these phases have yet to be directly observed under shock compression. In this work, we describe laser-driven shock compression experiments on polycrystalline alumina conducted at the Matter in Extreme Conditions endstation of the Linac Coherent Light Source. Ultrafast x-ray pulses (50 fs, 1012 photons/pulse) were used to probe the atomic-level response at different times during shock propagation and subsequent pressure release. At 107 ± 8 GPa on the Hugoniot, we observe diffraction peaks that match the orthorhombic Rh2O3(II) phase with a density of 5.16 ± 0.03 g cm−3. Upon unloading, the material transforms back to the α-corundum structure. Upon release to ambient pressure, densities are lower than predicted assuming isentropic release, indicating additional lattice expansion due to plastic work heating. Using temperature values calculated from density measurements, we provide an estimate of alumina’s strength on release from shock compression.
Oscillatory tribometry: transition from static to kinetic friction
Authors: Läuger Jörg
Published: December 2022

Oscillatory tribometry is presented as a new method for investigations on the transition from static friction to kinetic friction. The method distinguishes between purely elastic deformations and plastic frictional motions. Friction moduli are defined which are directly proportional to the stored and dissipated energy during an oscillation cycle. The elastic deformations are represented through the elastic friction modulus, which is directly proportional to the average elastic energy over an oscillation cycle, while the frictional motions yield the dissipation friction modulus, which is directly proportional to the average dissipated energy over an oscillation cycle. Energy dissipation in the static and boundary regime can be attributed to local dissolution of contact bonds or intermolecular adhesion bonds at the contact points, and thus to local slip. The ability to measure at very small sliding distances in oscillatory tribometer tests is a crucial prerequisite for such investigations. The methodology provides access to local friction phenomena at the intermolecular level while simultaneously measuring macroscopic samples. The application examples presented show that oscillatory tribometry on a highly sensitive rheometer is particularly valuable for applications such as dry contacts between polymers, elastomers or soft materials.
Coverage factors for efficient demonstration of compliance of low-frequency magnetic near-field exposures with basic restrictions
Authors: Xi Jingtian , Christ Andreas , Kuster Niels
Published: December 2022

Objective. Regulators require that wireless power transfer (WPT) systems and other strong magnetic field sources are compliant with the basic restrictions (BR) defined as the limits of the fields induced in the human body, i.e. the induced electric field/current density/specific absorption rate limits. This can be achieved by demonstrating compliance with the reference levels (RL) defined in air without the human body, i.e. the incident electric/magnetic field limits. Local sources, such as WPT transmitters, generate non-uniform fields that can locally exceed the RL while the induced fields are still well below the BR. In these cases, robust compliance with BR can be demonstrated, generally requiring a large number of simulations. In this study, we proposed an efficient evaluation using a homogeneous phantom and applying a coverage factor to account for the local field enhancements caused by the dielectric contrasts of the highly inhomogeneous human tissues. Approach. The generally applicable coverage factors were derived from a statistical analysis of the field enhancements observed on four magnetic near-field sources placed at different separation distances (2–80 mm) and locations on the back of 12 anatomical models. The field enhancements were characterized by the ratios between the peak induced fields in the anatomical models and those in the homogeneous half-space phantom (ϵ

r
= 55, σ = 0.75 S m−1, ρ = 1,000 kg m−3) at the same distance. Main results. The resulting 99th percentile coverage factors range from 1 and 9 depending on the dosimetric quantity. Significance. The use of these coverage factors reduces the compliance testing effort from hundreds of simulations to only one, and makes experimental testing feasible without the support of simulations. The study also demonstrates that running only a few use-case simulations with anatomical models may underestimate the exposure by more than 10 dB.
Characterisation of a split gradient coil design induced systemic imaging artefact on 0.35 T MR-linac systems
Authors: Marage Louis , Walker Paul-Michael , Boudet Julien , Fau Pierre , Debuire Pierre , Clausse Emmanuelle , Petitfils Aurélie , Aubignac Léone , Rapacchi Stanislas , Bessieres Igor
Published: December 2022

Objective. The aim of this work was to highlight and characterize a systemic ‘star-like’ artefact inherent to the low field 0.35 T MRIdian MR-linac system, a magnetic resonance guided radiotherapy device. This artefact is induced by the original split gradients coils design. This design causes a surjection of the intensity gradient in Z (or head-feet) direction. This artefact appears on every sequence with phase encoding in the head-feet direction. Approach. Basic gradient echo sequence and clinical mandatory bSSFP sequence were used. Three setups using manufacturer provided QA phantoms were designed: two including the linearity control grid used for the characterisation and a third including two homogeneity control spheres dedicated to the artefact management in a more clinical like situation. The presence of the artefact was checked in four different MRidian sites. The tested parameters based on the literature were: phase encoding orientation, slab selectivity, excitation bandwidth (BWRF), acceleration factor (R) and phase/slab oversampling (PO/SO). Main results. The position of this artefact is constant and reproducible over the tested MRIdian sites. The typical singularity saturated dot or star is visible even with the 3D slab-selection enabled. A management is proposed by decreasing the BWRF, the R in head-feet direction and increasing the PO/SO. The oversampling can be optimized using a formula to anticipate the location of artefact in the field of view. Significance. The star-like artefact has been well characterised. A manageable solution comes at the cost of acquisition time. Observed in clinical cases, the artefact may degrade the images used for the RT planning and repositioning during the treatment unless corrected.
A novel predictive analytics score reflecting accumulating disease burden—an investigation of the cumulative CoMET score
Authors: Monfredi Oliver , Andris Robert T , Lake Douglas E , Moorman J Randall
Published: December 2022

Objective. Predictive analytics tools variably take into account data from the electronic medical record, lab tests, nursing charted vital signs and continuous cardiorespiratory monitoring to deliver an instantaneous prediction of patient risk or instability. Few, if any, of these tools reflect the risk to a patient accumulated over the course of an entire hospital stay. Approach. We have expanded on our instantaneous CoMET predictive analytics score to generate the cumulative CoMET score (cCoMET), which sums all of the instantaneous CoMET scores throughout a hospital admission relative to a baseline expected risk unique to that patient. Main results. We have shown that higher cCoMET scores predict mortality, but not length of stay, and that higher baseline CoMET scores predict higher cCoMET scores at discharge/death. cCoMET scores were higher in males in our cohort, and added information to the final CoMET when it came to the prediction of death. Significance.  We have shown that the inclusion of all repeated measures of risk estimation performed throughout a patients hospital stay adds information to instantaneous predictive analytics, and could improve the ability of clinicians to predict deterioration, and improve patient outcomes in so doing.
A novel deep domain adaptation method for automated detection of sleep apnea/hypopnea events
Authors: Du Zonglin , Wang Jiao , Ren Yingxin , Ren Yingtong
Published: December 2022

Objective. Sleep apnea–hypopnea syndrome (SAHS) is a common sleep-related respiratory disorder that is generally assessed for severity using polysomnography (PSG); however, the diversity of sampling devices and patients makes this not only costly but may also degrade the performance of the algorithms. Approach. This paper proposes a novel deep domain adaptation module which uses a long short-term memory–convolutional neural network embedded with the channel attention mechanism to achieve autonomous extraction of high-quality features. Meanwhile, a domain adaptation module was built to achieve domain-invariant feature extraction for reducing the differences in data distribution caused by different devices and other factors. In addition, during the training process, the algorithm used the last second label as the label of the PSG segment, so that second-by-second evaluation of respiratory events could be achieved. Main results. The algorithm applied the two datasets provided by PhysioNet as the source and target domains. The accuracy, sensitivity and specificity of the algorithm on the source domain were 86.46%, 86.11% and 93.17%, respectively, and on the target domain were 83.63%, 82.52%, 91.62%, respectively. The proposed algorithm showed strong generalization ability and the classification results were comparable to the current advanced methods. Besides, the apnea–hypopnea index values estimated by the proposed algorithm showed a high correlation with the manual scoring values on both domains. Significance. The proposed algorithm can effectively perform SAHS detection and evaluation with certain generalization.
Remobilized dust dynamics and inventory evolution in ITER-like start-up plasmas
Authors: Vignitchouk L , Paschalidis K , Ratynskaia S , Tolias P , Pitts R A
Published: December 2022

The dynamics of remobilized metallic dust are simulated with the MIGRAINe code in low-power ITER discharges meant to emulate reactor start-up environments. The particle size and speed distributions are varied along with plasma profiles to investigate the influence of initial and background parameters on high-Z impurity production by vaporization as well as long-term in-vessel dust inventory evolution over the course of consecutive discharges. Simulation output data regarding beryllium remobilization can be integrated into more global ITER models to guide the operation of dust diagnostics and facilitate the compliance with nuclear safety restrictions, while results on tungsten particles serve as a basis for first assessments of dust dynamics in DEMO.
Dipolar physics: a review of experiments with magnetic quantum gases
Authors: Chomaz Lauriane , Ferrier-Barbut Igor , Ferlaino Francesca , Laburthe-Tolra Bruno , Lev Benjamin L , Pfau Tilman
Published: December 2022

Since the achievement of quantum degeneracy in gases of chromium atoms in 2004, the experimental investigation of ultracold gases made of highly magnetic atoms has blossomed. The field has yielded the observation of many unprecedented phenomena, in particular those in which long-range and anisotropic dipole–dipole interactions (DDIs) play a crucial role. In this review, we aim to present the aspects of the magnetic quantum-gas platform that make it unique for exploring ultracold and quantum physics as well as to give a thorough overview of experimental achievements. Highly magnetic atoms distinguish themselves by the fact that their electronic ground-state configuration possesses a large electronic total angular momentum. This results in a large magnetic moment and a rich electronic transition spectrum. Such transitions are useful for cooling, trapping, and manipulating these atoms. The complex atomic structure and large dipolar moments of these atoms also lead to a dense spectrum of resonances in their two-body scattering behaviour. These resonances can be used to control the interatomic interactions and, in particular, the relative importance of contact over dipolar interactions. These features provide exquisite control knobs for exploring the few- and many-body physics of dipolar quantum gases. The study of dipolar effects in magnetic quantum gases has covered various few-body phenomena that are based on elastic and inelastic anisotropic scattering. Various many-body effects have also been demonstrated. These affect both the shape, stability, dynamics, and excitations of fully polarised repulsive Bose or Fermi gases. Beyond the mean-field instability, strong dipolar interactions competing with slightly weaker contact interactions between magnetic bosons yield new quantum-stabilised states, among which are self-bound droplets, droplet assemblies, and supersolids. Dipolar interactions also deeply affect the physics of atomic gases with an internal degree of freedom as these interactions intrinsically couple spin and atomic motion. Finally, long-range dipolar interactions can stabilise strongly correlated excited states of 1D gases and also impact the physics of lattice-confined systems, both at the spin-polarised level (Hubbard models with off-site interactions) and at the spinful level (XYZ models). In the present manuscript, we aim to provide an extensive overview of the various related experimental achievements up to the present.
Crystalline and optoelectronic properties of Ge1−x
Sn
x
/high-Si-content-Si
y
Ge1−x−y
Sn
x
double-quantum wells grown with low-temperature molecular beam epitaxy
Authors: Zhang Shiyu , Shibayama Shigehisa , Nakatsuka Osamu
Published: December 2022

In this study, we investigated the impact of the growth temperatures of molecular beam epitaxy method for the Si
y
Ge1−x−y
Sn
x
barrier with a Si content over 20% of Ge1−x
Sn
x
/Si
y
Ge1−x−y
Sn
x
single-quantum well (QW) on their crystalline and photoluminescence (PL) properties. As a result, we found that lowering T
SiGeSn down to 100 °C achieves the superior crystallinity and the higher PL efficiency at room temperature. It was owing to the suppression of the Sn segregation according to the surface morphology observation. Based on this finding, we realized the epitaxial growth of Ge1−x
Sn
x
/Si
y
Ge1−x−y
Sn
x
double-QWs at 100 °C. We verified the superior crystallinity with the abrupt interface by x-ray diffraction and scanning transmission electron microscopy. In this study, we discussed the optical transition mechanism of the single- and double-QWs based on the band alignment simulation. Finally, we found that the double-QW grown at 100 °C can sustain its crystalline structure against annealing at the N2 atmosphere up to 350 °C, and the PL performance can be also improved by the thermal treatment at around 350 °C.
Adaptive disturbance observer-based improved super-twisting sliding mode control for electromagnetic direct-drive pump
Authors: Lu Yingtao , Tan Cao , Ge Wenqing , Zhao Yanjun , Wang Geng
Published: December 2022

In this study, to enhance the frequency-flow characteristics of the novel electromagnetic direct-drive pump (EDDP). An adaptive disturbance observer-based improved super-twisting sliding mode control (ISTSMC-ADOB) is proposed to address the problem in which the response quality is deteriorated by factors such as parameter mismatch and disturbance. An adaptive disturbance observer (ADOB) is designed to achieve adaptive compensation, avoid the use of high-gain feedback, and extend the applicability of the conventional disturbance observer. An improved super-twisting sliding mode control (ISTSMC) based on the fast terminal sliding mode algorithm is designed to ensure faster convergence of the error in finite time. By combining the ADOB with the ISTSMC, the conservative parameter selection of the sliding mode control (SMC) is avoided, and the accuracy and robustness are further strengthened. The stability is analyzed based on Lyapunov. The results show that the proposed method effectively improves the steady-state accuracy, response speed, and robustness in trajectory tracking of the electromagnetic linear actuator for the EDDP. This further enhances the frequency-flow characteristics of the system.
A novel structural–functional integration piezoelectric thruster for miniature unmanned underwater vehicles
Authors: Liu Rui , Zhao Heng , Wang Liang , Jin Jiamei , Lai Dongyang , Chen Yuhang
Published: December 2022

Unmanned underwater vehicles (UUVs) play a vital role in marine exploration, and can achieve an extension of human hands and eyes to help researchers reach inaccessible and complex underwater spaces. However, the developed UUVs are driven by electromagnetic motors that also make it difficult to miniaturize due to the existence of the transmission system. Additionally, electromagnetic motors need to be protected to against water intrusion, especially in the deep sea. Therefore, in order to solve the above-mentioned problems, a novel structure-functional integration piezoelectric thruster for miniature UUVs is proposed in this study. Based on the converse piezoelectric effect and the direct friction drive principle, rudders and propellers can be alternately driven by a piezoelectric actuator, constructing the thrust unit and the steering unit of the piezoelectric thruster, respectively. Therefore, this makes the structure and function of the piezoelectric thruster integrated. Finite element simulations are first conducted to determine the geometrical sizes of the proposed actuator. The efficiency of the designed piezoelectric actuator is then confirmed using an underwater vibration measurement. Finally, experimental evaluations of the output performance of the piezoelectric thruster are performed. In the propulsion mode, the maximum rotation speed and thrust of the positive and negative propeller of the prototype with an excitation voltage of 600 Vpp were 404 rpm/0.10 N and 413 rpm/0.11 N, respectively. In the cooperative working mode, 20.00 kHz was used as the driving frequency, and the yaw and pitch rudders had the maximum average angle velocities of 92 deg s−1 and 90 deg s−1 for an excitation voltage of 600 Vpp, respectively. The maximum rotation speed and thrust of the positive and negative propellers of the prototype with an excitation voltage of 600 Vpp were 133 rpm/0.01 N and 132 rpm/0.01 N, respectively. According to experimental findings, the prototype piezoelectric thruster exhibits excellent mechanical properties.
Dimension dependent properties of subdiffusions in damping force fields from an inference perspective
Authors: He Yue , Kawai Reiichiro
Published: December 2022

We investigate the fractional Fokker-Planck equation subject to a damping force with an emphasis on its dimension dependent properties. We reveal a variety of surprising properties of its solution through the lens of the probability density function of the corresponding stochastic process with nonlinear mean square displacements, such as existence, singularity, regularity, modality, stationarity and second-order structure, which are largely dependent on the dimension and the random clock. Taking into account that the trajectory information is most often collected from multidimensional systems, the discovered facts have the potential to play important roles as key foundations and alerts for inference, model identification and prediction, when departing from the well-understood univariate framework.
Characterizations of -flat curvature tensor on spacetimes and

f(r,T)

-gravity
Authors: De Uday Chand , Hazra Dipankar
Published: December 2022

The prime goal of this article is to characterize spacetimes endowed with



-flat curvature tensor. It is demonstrated that a 4-dimensional



-flat perfect fluid spacetime is either a de-Sitter spacetime or locally isometric to Minkowski spacetime under certain energy condition. Moreover, it is established that a Ricci simple



-flat spacetime becomes a Robertson-Walker spacetime. In addition, we shown that a Ricci simple spacetime with harmonic



-curvature tensor is a generalized Robertson-Walker spacetime. Also, we explain several conclusions based on



-flat generalized Robertson-Walker spacetimes. Finally, we investigate



-flat spacetimes that satisfy the

f

r
,


-gravity and

f

r
,



m

-gravity.
A 1-MV low-jitter high-reliability multi-stage equal breakdown probability gas switch
Authors: Shang Wei , Su Jiancang , Zeng Bo , Gao Mingzhu , Li Rui , Li Yongdong , Lv Donghui , Shao Shuai
Published: December 2022

This paper presents the development of a novel megavolt-class equal breakdown probability (EBP) multi-stage self-discharge gas switch for high power microwave generation with low breakdown jitter and high reliability. With the joint distribution of breakdown probability for ‘n’ identical stages of EBP gas switch, the advantages of diminishing the breakdown jitter and omitting the complex breakdown order problem are hence disclosed in considerable details with the aid of probability computation method. Based on theoretical analysis, a 5 stages 1-MV EBP multi-stage gas switch is designed in which periodic cog profile cathode is proposed to further decrease the breakdown jitter. The performances of EBP switch are tested at the repetition rate of 1,10,20,50 Hz over 1000 successive pulses with breakdown jitter as low as 2.7% ,energy efficiency as high as 90% and pulse rising time as low as 5 ns. The overall performance of EBP gas switch shows great potential in compact and reliable high power microwave generating system.
Constraining ultra-high-energy cosmic ray composition through cross-correlations
Authors: Tanidis Konstantinos , Urban Federico R. , Camera Stefano
Published: December 2022

The chemical composition of the highest end of the ultra-high-energy cosmic ray spectrum is very hard to measure experimentally, and to this day it remains mostly unknown. Since the trajectories of ultra-high-energy cosmic rays are deflected in the magnetic field of the Galaxy by an angle that depends on their atomic number Z, it could be possible to indirectly measure Z by quantifying the amount of such magnetic deflections. In this paper we show that, using the angular harmonic cross-correlation between ultra-high-energy cosmic rays and galaxies, we could effectively distinguish different atomic numbers with current data. As an example, we show how, if Z = 1, the cross-correlation can exclude a 39% fraction of Fe56 nuclei at 2σ for rays above 100 EeV.
Quantitative measurement of the charge carrier concentration using dielectric force microscopy
Authors: Lai Junqi , Chen Bowen , Xing Zhiwei , Li Xuefei , Lu Shulong , Chen Qi , Chen Liwei
Published: December 2022

The charge carrier concentration profile is a critical factor that determines semiconducting material properties and device performance. Dielectric force microscopy (DFM) has been previously developed to map charge carrier concentrations with nanometer-scale spatial resolution. However, it is challenging to quantitatively obtain the charge carrier concentration, since the dielectric force is also affected by the mobility. Here, we quantitative measured the charge carrier concentration at the saturation mobility regime via the rectification effect-dependent gating ratio of DFM. By measuring a series of n-type GaAs and GaN thin films with mobility in the saturation regime, we confirmed the decreased DFM-measured gating ratio with increasing electron concentration. Combined with numerical simulation to calibrate the tip–sample geometry-induced systematic error, the quantitative correlation between the DFM-measured gating ratio and the electron concentration has been established, where the extracted electron concentration presents high accuracy in the range of 4 × 1016 – 1 × 1018 cm−3. We expect the quantitative DFM to find broad applications in characterizing the charge carrier transport properties of various semiconducting materials and devices.
Mechanical enhancement and weakening in Mo6S6 nanowire by twisting
Authors: Xu Ke , Lin Yanwen , Shi Qiao , Fu Yuequn , Yang Yi , Zhang Zhisen , Wu Jianyang
Published: December 2022

The torsional, bending and tensile mechanical properties of Mo6S6 nanowire are examined by molecular dynamics (MD) simulations with a first-principles-based reactive force field (ReaxFF). It is found that Mo6S6 nanowire shows unique mechanical properties such as high torsional and bending flexibility, high Young’s modulus and strength, and negative Poisson’s ratio. The Mo6S6 nanowire can be strengthened or weakened via twisting, depending on the twist angle. The Mo6S6 nanowire with a slight twist angle shows brittle failure, whereas it with a large twist angle exhibits ductile failure and necking behavior. Twisted Mo6S6 nanowires show a crossover in the negative Poisson’s ratio at critical strains, that is, Poisson’s ratio first decreases but then increases, with a minimum value down to around −0.8 at the strain of 0.01 as the twist angle is 21.0 °/nm. The negative Poisson’s ratio and the crossover are explained by the bond transform that makes zero angles to the wire cross-section.
Detecting physical laws from data of stochastic dynamical systems perturbed by non-Gaussian α-stable Lévy noise
Authors: Lu Linghongzhi , Li Yang , Liu Xianbin
Published: December 2022

Massive data from observations, experiments and simulations of dynamical models in scientific and engineering fields make it desirable for data-driven methods to extract basic laws of these models. We present a novel method to identify such high dimensional stochastic dynamical systems that are perturbed by a non-Gaussian α-stable Lévy noise. More explicitly, firstly a machine learning framework to solve the sparse regression problem is established to grasp the drift terms through one of nonlocal Kramers–Moyal formulas. Then the jump measure and intensity of the noise are disposed by the relationship with statistical characteristics of the process. Three examples are then given to demonstrate the feasibility. This approach proposes an effective way to understand the complex phenomena of systems under non-Gaussian fluctuations and illuminates some insights into the exploration for further typical dynamical indicators such as the maximum likelihood transition path or mean exit time of these stochastic systems.
Topological properties of tetratomic Su–Schrieffer–Heeger chains with hierarchical long-range hopping
Authors: Li Guan-Qiang , Wang Bo-Han , Tang Jing-Yu , Peng Ping , Dong Liang-Wei
Published: December 2022

We propose a new generalized Su–Schrieffer–Heeger model with hierarchical long-range hopping based on a one-dimensional tetratomic chain. The properties of the topological states and phase transition, which depend on the cointeraction of the intracell and intercell hoppings, are investigated using the phase diagram of the winding number. It is shown that topological states with large positive/negative winding numbers can readily be generated in this system. The properties of the topological states can be verified by the ring-type structures in the trajectory diagram of the complex plane. The topological phase transition is strongly related to the opening (closure) of an energy bandgap at the center (boundaries) of the Brillouin zone. Finally, the non-zero-energy edge states at the ends of the finite system are revealed and matched with the bulk–boundary correspondence.
Investigating the fission dynamics of the following neutron shell closed nuclei within a stochastic dynamical approach: 210Po, 212Rn, and 213Fr*
Authors: Arora Divya , Sugathan P. , Chatterjee A.
Published: December 2022

The dissipative dynamics of nuclear fission is a well confirmed phenomenon that can be either described by a Kramers-modified statistical model or by a dynamical model employing the Langevin equation. Although dynamical models as well as statistical models incorporating fission delays have been found to explain the measured fission observables in several studies, they present conflicting results for shell closed nuclei in the mass region of 200. Notably, an analysis of the recent data on neutron shell closed nuclei in the excitation energy range of 40

80 MeV failed to provide a satisfactory description of the data, which was attributed to a mismatch with shell effects and/or entrance channel effects, without reaching a definite conclusion. In the present study, we demonstrate that a well established stochastic dynamical code can simultaneously reproduce the available data for pre-scission neutron multiplicities and fission and evaporation residue excitation functions for the following neutron shell closed nuclei

Po and

Rn and their isotopes

Po and

Rn without the need for including any extra shell or entrance channel effects. The relevant calculations are performed by using a phenomenological universal friction form factor with no ad-hoc adjustment of the model parameters. However, we note a significant deviation, beyond experimental errors, for some Fr isotopes.
Elongation effect on beta-induced Alfvén eigenmode
Authors: Li Gengxian , Li Yueyan , Xiao Yong
Published: December 2022

Beta induced Alfvén eigenmode (BAE) can be an important candidate for ion loss in burning plasmas. Elongation effect on BAE has been investigated by the gyrokinetic eigenvalue code DAEPS in this work. We construct a shaped equilibrium model by modifying local s − α model with which the capability of the DAEPS code has been extended to study the elongation effect. It is discovered that the BAE growth rate first increases with elongation factor κ, reaches a maximum and then decreases. This trend occurs for many different values of η
i. We find that, in the weak or moderate elongation region, the BAE instability is reactive type and mainly determined by the fluid/MHD effects, namely the combination of stabilizing field line bending term and destabilizing interchange drive in the vorticity equation. However, in the strong elongation region, the BAE instability becomes dissipative and is mainly driven by the wave–particle resonance effect embedded in δW

k
since the fluid driving damps away. It is also discovered that the wave–particle resonance decreases with elongation in this region, which is due to the decrease of the geodesic curvature with elongation and leads to the decrease in the growth rate of BAE.
A two-step strategy to deposit a hydroxyapatite coating on polydopamine-coated polymer fibers
Authors: Li Jiaxin , Li Ting-Ting , Zhang Ying , Shiu Bing-Chiuan , Lin Jia-Horng , Lou Ching-Wen , Liu Liyan
Published: December 2022

As the main inorganic component of human bones and teeth, hydroxyapatite (HA), with excellent bioactivity and biocompatibility, shows great potential in the bone tissue engineering field. Marine mussel-inspired polydopamine (PDA) possesses unique functional groups and thus can absorb the calcium ions from extracellular fluid, thereby triggering the precipitation of HA. This study is based on a two-step strategy. Using the chemical activity of PDA, polyvinyl alcohol/polylactic acid (PVA/PLA) braids were coated with a PDA layer that served as a template for the electrochemical deposition of a HA layer. The test results indicate that the resulting HA crystals were assembled on the polymer fibers in an urchin-like mannerwith a stratified structure. Subsequently, the HA/PDA-PVA/PLA braided bone scaffolds were immersed in simulated body fluid for ten days, after which the bone scaffolds were found to be completely coated with HA, indicating a good biomineralization capability. Cell activity of HA/PDA-PVA/PLA scaffolded by dopamine-assisted electrodeposition was 178.8% than that of PVA/PLA braids. This HA coating layer inspired by biochemical strategies may be useful in the field of bone tissue engineering.
Active mode single-pixel non-line-of-sight imaging system based on second-order correlation and diffraction
Authors: Li Mengdi , Xu Xiping , Wang Xiaoqian , Yao Zhihai , Wang Xin
Published: December 2022

Non-line-of-sight (NLOS) imaging relies on capturing light that has been weakened due to multiple reflections and recovering the occluded scene with high quality is very challenging. To improve the quality of NLOS imaging, an active mode single-pixel NLOS imaging reconstruction framework based on the second-order correlation function and diffraction inverse operation is proposed. Under the collective effect of illumination pattern and single-pixel detector light intensity, the inverse imaging problem is first solved by a statistically weighted average, and then, an additional process is connected to reduce the influence of diffraction on reconstructed image quality based on the Fourier transform and inverse diffraction operation. The simulation and experimental results show that the proposed method with the Hadamard pattern and diffraction inverse operation, which achieved the SSIM value of 0.9286, is superior to the random pattern at a full sampling rate. The lens aperture size, pattern location, and the number of measurements have a significant effect on the system. Therefore, the proposed scheme has potential practical applications.
Modeling study on different discharge characteristics in pulsed discharges with and without barriers on electrodes
Authors: GAO Shuhan , WANG Xucheng , ZHANG Yuantao
Published: December 2022

High-pressure nanosecond pulsed discharges (NPDs) have attracted increasing attention in recent years due to their wide potential applications. In this study, a barrier-free NPD in pure helium plasma at 120 Torr was numerically investigated by a one-dimensional self-consistent fluid model, and its current–voltage characteristics show very different behaviors from those in pulsed dielectric barrier discharges (DBDs), indicating an entirely distinctive discharge evolution in pulsed discharges with or without barriers on electrodes. Without the control of barriers, the computational data suggest that the discharge current increases very sharply during the plateau phase of the pulsed voltage and reaches its peak value at approximately the instant when the pulsed voltage starts to drop, together with a gradual reduction in the sheath thickness and an increase in electric field in the sheath region, which is in good agreement with experimental observations. By increasing the voltage plateau width and repetition frequency, the discharge current density from the simulation can be substantially enhanced, which cannot be observed in conventional pulsed DBDs, and the spatial distributions of the electric field and charged particles are given to unravel the underlying physics. From the computational data, the distinctive discharge characteristics in barrier-free NPDs are deeply understood, and could be further optimized by tailoring the waveform of the pulsed voltage to obtain desirable plasmas for applications.
James Webb Space Telescope image peers into the chaos of the Cartwheel galaxy
Authors: Banks Michael
Published: December 2022

A stunning image taken by the James Webb Space Telescope (JWST) reveals new details about star formation and the black hole at the heart of the Cartwheel galaxy.
Improving soft skills crucial to keep women in science
Authors: Allen Michael
Published: December 2022

Early-career women in science who develop more “soft skills” see a boost in their self-confidence and likelihood to stay in work, according to a study.
Quantum computing gets down to business
Authors: Boerkamp Martijn
Published: December 2022

Martijn Boerkamp reports how investments into quantum computing have ballooned in the past year, bringing huge expectations for the sector.
Deathly starts
Authors: Raif Erin
Published: December 2022

A response to the Lateral Thoughts quiz in August 2022 about the opening lines to popular-science books.
Knitting space–time out of quantum entanglement
Authors: Aldegunde Clara
Published: December 2022

Clara Aldegunde goes on an intellectual journey to understand how quantum phenomena may thread together the fabric of space–time, giving rise to our reality.
High-resolution maskless patterning of AgNWs based on adhesion enhancement of a printed conductive polymer
Authors: Kim Geonhee , Yoon Jinsu , Yoon Hyungsoo , Cho Hyeon , Seo Jiseok , Hong Yongtaek
Published: December 2022

Facile high-resolution patterning of silver nanowires (AgNWs) is a key enabling technology for expanding their usage to flexible and stretchable electronics applications. Although various patterning methods have been proposed, only high-cost and complex mask-based methods have demonstrated potential micrometer-scale pattern-ability, which have no design freedom of changing patterns in a facile manner. Herein, we suggest a maskless high-resolution patterning method by combining an adhesive underlayer and inkjet-printed conductive polymer patterns. AgNWs located between them are tightly bonded and thus are resistant to a solvent-based rinsing process. AgNWs under the conductive polymer patterns remain while uncovered AgNWs are removed during the rinsing process. Our approach allows easy patterning of AgNWs on various substrates including glass, plastic, and stretchable elastomer. The excellent mechanical properties of AgNW interconnects are demonstrated in a stretchable light-emitting diode array. By introducing an electrohydrodynamic printing method, high-resolution AgNW patterns with linewidths below 20 µm are fabricated, which are used for a heater based on transparent grid AgNW electrodes. Based on our results, we believe that our method paves the way for a convenient patterning process of high-resolution electrode circuits with a high degree of freedom even on a deformable platform.
Hardiness and Grit as Drivers of South African Child Protection Social Workers’ Occupational Resilience
Authors: Molakeng Mahloma Hebert , Boonzaaier Emma , Truter Elmien , Fouché Ansie
Published: December 2022

Child protection social workers (CPSWs) perform statutory duties and often work in hostile work contexts. Nevertheless, some CPSWs are reportedly resilient, thus adjusting well despite exposure to occupational adversities. We followed a qualitative descriptive design in which twenty CPSWs from the Western Cape and the Free State provinces described their sources of occupational resilience during semi-structured interviews. Their self-reported sources of resilience were informed by (1) a high degree of personal agency; (2) navigating a responsive and supportive ecology; (3) commitment to a meaningful purpose; (4) prioritising self-care and (5) religious practices. These sources of resilience confirm what we already know, but our findings go beyond earlier reports and contribute towards a more nuanced understanding of how hardiness and grit fundamentally drive the occupational resilience of CPSWs.
CCL18 promotes migration and invasion of multiple myeloma cells and is associated with poor prognosis
Authors: Qiao Bing , Chen Lei , Cheng Qianwen , Wang Guangqi , Li Qun , Zhang Bo , Li Junying , Hu Yu , Sun Chunyan
Published: December 2022

CCL18 has recently been implicated in malignancies and is increasingly mentioned as a potential tumoral biomarker and furtherly a molecular target for therapeutic intervention, but its expression and clinical significance in multiple myeloma have not been explored. Serum CCL18 levels were measured by ELISA method in 254 newly diagnosed multiple myeloma (NDMM), 21 monoclonal gammopathy of undetermined significance (MGUS) and 22 healthy adults. The study suggests that the serum CCL18 level in NDMM patients was significantly higher than that in MGUS and healthy adults. High level of CCL18 were associated with advanced ISS and R-ISS stages in MM. Patients with high serum CCL18 displayed a significantly more frequent occurrence of renal impairment and hypercalcemia, while the proportion of achieving complete remission (CR) was lower. More importantly, Cox analysis identified CCL18 and LDH as independent predictors of PFS in MM patients, whereas CCL18, creatinine and LDH were independent predictors of OS. Finally, we show that CCL18 can promote migration and invasion of myeloma cell lines RPMI8226 and MM.1S. CCL18 may play a tumor-promoting role by increasing the migration and invasion abilities of myeloma cells.
Functional conservation of Anopheline linalool receptors through 100 million years of evolution
Authors: Huff Robert M , Pitts Ronald Jason
Published: December 2022

Insects rely on olfactory receptors to detect and respond to diverse environmental chemical cues. Detection of semiochemicals by these receptors modulates insect behavior and has a direct impact on species fitness. Volatile organic compounds (VOCs) are released by animals and plants and can provide contextual cues that a blood meal host or nectar source is present. One such VOC is linalool, an enantiomeric monoterpene, that is emitted from plants and bacteria species. This compound exists in nature as one of two possible stereoisomers, (R)-(–)-linalool or (S)-(+)-linalool. In this study, we use a heterologous expression system to demonstrate differential responsiveness of a pair of Anopheline odorant receptors (Ors) to enantiomers of linalool. The mosquitoes Anopheles gambiae and Anopheles stephensi encode single copies of Or29 and Or53, which are expressed in the labella of An. gambiae. (S)-(+)-linalool activates Or29 orthologs with a higher potency than (R)-(–)-linalool, while the converse is observed for Or53 orthologs. The conservation of these receptors across a broad range of Anopheline species suggests they may function in the discrimination of linalool stereoisomers, thereby influencing the chemical ecology of mosquitoes. One potential application of this knowledge would be in the design of novel attractants or repellents to be used in integrated pest management practices.
Impact of farmers’ social relationships on productivity: a multiplex network analysis
Authors: Gambrah Patience Pokuaa , Yu Qian
Published: December 2022

An individual’s productivity is strongly related to work- and non-work-related interactions. Thus, the literature on farmers’ productivity often explores single-layer networks that illustrate the single categories of social relationships. In this study, we investigated farmers’ productivity using a multiplex structure underlying social interaction networks. Relational data were obtained from farmers in four different categories of social relationships. The multiplex network was analysed by applying multiplex degree centrality and layer-by-layer comparison. Also, power and role were analysed through the use of external data by determining their intra-layer correlation. The findings show that diverse types of relationships exist together and they positively affect farmers’ productivity in multiple ways and enhance their innovation capacity. Only 6 out of the 73 farmers had high-degree centrality (> 10), with 18–63$\%$ relevance for the six farmers in the two layers—farming advice (FA) and loans (LO) layers—that the farmers considered important to their productivity. These farmers were more likely to be productive and help improve the productivity of others linked to them. Further, 62$\%$ of the edges in the social gathering and personal advice layers were similar, whereas only 3$\%$ of those in the FA and LO layers were similar, confirming the significance of the latter layers. The influence of social structures on farmers’ productivity implies that social connections enhance farmers’ confidence. The external data further confirm that the formation of some links depends on trust and power, whereas others do not.