bluuebunny/crossref_metadata_2025 huggingface dataset:
CME versus D3 Dissection for Colon Cancer
Authors: Kobayashi Hirotoshi , West Nicholas P.
Published: November 2020

Over the past 30 years, rectal cancer surgery has been standardized by total mesorectal excision. More recently, some have suggested that colon cancer surgery should be standardized by complete mesocolic excision (CME) with central vascular ligation (CVL), especially in Western countries. Surgeons undertaking CME with CVL report optimal outcomes. Sharp dissection within the embryological plane and high vascular ligation at the vessel origin are essential. In Japan, a similar concept, D3 dissection, has been adopted for decades. Although both surgical procedures are similar, distinct differences exist. Some surgeons are confused about the principles and practice of these two procedures. As well as overviewing the theory behind CME with CVL and D3 dissection, the technical details of both procedures are described.
Coupling of heat flux and vortex polarization in superfluid helium
Authors: Saluto Lidia , Jou David
Published: November 2020

We consider a macroscopic description of the mutual influence between heat flux and vortex polarization in superfluid helium, in which the vortices produce a lateral deviation of the heat flux, and the heat flux produces a lateral drift of vortices. This coupling is a consequence of a microscopic Magnus force and mutual friction force between the vortices and the flow of excitations carrying the heat. We keep track of these effects with simplified macroscopic equations, and we apply them to second sound propagation between rotating concentric cylinders and to spatial distribution of polarization across a rectangular channel with vortices polarized orthogonally to the channel in the presence of an imposed heat flux.
Device for the field measurements of frequency-dependent soil properties in the frequency range of lightning currents
Authors: Kuklin D.
Published: November 2020

Existing approaches for the field measurements of the frequency-dependent soil properties take a significant amount of time, making it difficult to obtain new experimental data and study the electrical soil properties further. However, a relatively uncomplicated measurement device assembled from accessible electronic components can make the measurements almost as easy as those for the regular low-frequency resistivity. This article presents a detailed description of such a device: the description includes the functional scheme, pseudocodes for central parts of the calculation algorithm, used electronic components, and working principle of the device. This article discusses the reasons behind the chosen parameters of the device (such as isolation between the measurement circuits, generated signal waveform, and usage of the electrode arrays) and addresses other possible approaches for the measurements. This paper also provides several measurement results and a comparison with a calculation result for a particular electrode array configuration. Finally, this work describes essential aspects affecting the accuracy of measurement results.
On classical solutions of the two-species Vlasov–Poisson system in R3 with infinite charge
Authors: Xiong Hang , Zhang Xianwen
Published: November 2020

We are concerned with the initial value problem for the two-species Vlasov–Poisson system in the plasma physics case in R3. It is assumed that initially the phase-space densities of ions and electrons decay only polynomially with respect to the velocities, but the net charge density vanishes at infinity with a polynomial rate, which allows for defining the electrostatic field. This situation falls into the so-called infinite charge problem, and there is no rigorous result as far as we know. Local existence, uniqueness, and continuation criteria of the classical solution are established in this paper. Moreover, this article also shows the existence of a global solution in the case of radial symmetry.
Rashba band splitting in two-dimensional Ruddlesden–Popper halide perovskites
Authors: Yu Shidong , Na Guangren , Luo Shulin , Rubel Oleg , Zhang Lijun
Published: November 2020

Due to the presence of heavy elements and the dynamic nature of hybrid halide perovskites, the strong spin–orbit coupling effect can give rise to Rashba band splitting in these materials. Despite many reports on the Rashba effect in 3D perovskites like CH3NH3PbI3, little is known about its presence in two-dimensional Ruddlesden–Popper (2DRP) perovskites. In this work, we use first-principle calculations to investigate the magnitude and origin of the Rashba effect in three families of 2DRP perovskites. We demonstrate the correlation between the splitting magnitude and the octahedron distortions. Moreover, different numbers of inorganic layers, spacer cations, and A-site cations have a great influence on the Rashba splitting through different mechanisms. While structures with C6H5C2H4NH3 (PEA) have a significant Rashba splitting only in the monolayer condition, C4H9NH3 (BA) induces large distortion by tilting the CH3NH3 (MA) cations around all octahedrons, giving rise to a larger Rashba splitting with an increasing number of inorganic layers. Our work elucidates the magnitude and origin of the Rashba splitting in 2DRP perovskites and provides guidelines for the manipulation of the Rashba splitting in these materials.
Chimera states in coupled map lattices: Spatiotemporally intermittent behavior and an equivalent cellular automaton
Authors: Singha Joydeep , Gupte Neelima
Published: November 2020

We construct an equivalent cellular automaton (CA) for a system of globally coupled sine circle maps with two populations and distinct values for intergroup and intragroup coupling. The phase diagram of the system shows that the coupled map lattice can exhibit chimera states with synchronized and spatiotemporally intermittent subgroups after evolution from random initial conditions in some parameter regimes, as well as to other kinds of solutions in other parameter regimes. The CA constructed by us reflects the global nature and the two population structure of the coupled map lattice and is able to reproduce the phase diagram accurately. The CA depends only on the total number of laminar and burst sites and shows a transition from co-existing deterministic and probabilistic behavior in the chimera region to fully probabilistic behavior at the phase boundaries. This identifies the characteristic signature of the transition of a cellular automaton to a chimera state. We also construct an evolution equation for the average number of laminar/burst sites from the CA, analyze its behavior and solutions, and correlate these with the behavior seen for the coupled map lattice. Our CA and methods of analysis can have relevance in wider contexts.
Linear and nonlinear interactions between an interface and bulk vortices in Richtmyer–Meshkov instability
Authors: Matsuoka Chihiro , Nishihara Katsunobu , Cobos-Campos Francisco
Published: November 2020

When a planar shock hits a corrugated interface between two fluids, the Richtmyer–Meshkov instability (RMI) occurs. Vortices are generated in bulk behind the transmitted and reflected shocks in RMI. As the shock intensity becomes larger, the stronger bulk vortices are created. The nonlinear evolution of RMI is investigated within the vortex sheet model (VSM), taking the nonlinear interaction between the interface and the vortices into account. The fluid becomes incompressible as the shocks move away from the interface, and VSM can then be applied. The vorticity and position of the bulk vortices obtained from the compressible linear theory [F. Cobos-Campos and J. G. Wouchuk, Phys. Rev. E93, 053111 (2016)] are applied as initial conditions of the bulk point vortices in VSM. The suppression of RMI due to the bulk vortices is observed in the region such that the corrugation amplitude is less than one-tenth of the wavelength, and the reduction of the growth is quantitatively evaluated and compared with the compressible linear theory. In the nonlinear stage, the interaction between the interface and the bulk vortices strongly affects the interfacial shape and the dynamics of bulk vortices, e.g., the creation of a vortex pair is observed. Strong bulk vortices behind the transmitted shock enhance the growth of spike, supplying flow from spike root to its top and mushroom umbrella in the fully nonlinear stage.
Sensitization of glioblastoma cells to temozolomide by a helium gas discharge tube
Authors: Yao Xiaoliang , Lin Li , Soni Vikas , Gjika Eda , Sherman Jonathan H. , Yan Dayun , Keidar Michael
Published: November 2020

Glioblastoma is one of the most aggressive brain cancers. Chemotherapy is a standard modality for its therapy. Here, we demonstrated a novel strategy using a helium gas discharge tube as a tunable electromagnetic emission source to sensitize glioblastoma cells to the cytotoxicity of temozolomide (TMZ), a widely used drug for glioblastoma. After a single 7-min of treatment, the efficacy of TMZ was enhanced in two typical glioblastoma cell lines U87MG and A172 without affecting a normal human astrocyte cell line hTERT/E6/E7. The discharge tube is a non-invasive approach, which provides a safe, controllable, stable, and low-cost modality to improve the conventional chemotherapy.
Elastic scattering of electron in neutral plasma: Interaction model and plasma environment effects
Authors: Quan W. L. , Sun X. W. , Chen Q. F.
Published: November 2020

Elastic scattering of electrons in a plasma is studied for its pivotal role in relating transport properties to plasma composition. A unified effective potential model is developed to describe the interactions between electrons and atoms/ions in plasma. It not only contains the static Coulomb, polarization, and exchange interaction but also considers plasma environment effects with a Muffin-tin model based on the Roothaan–Hartree–Fock atomic wave functions. For electron–electron and electron–ion interactions, the dynamical screening effect is also considered by a velocity-dependent screening length. The validity of the potential model is demonstrated in the specific case of argon plasma. The calculated differential, total, and momentum transfer cross sections, as well as the electrical conductivities at varying plasma densities and temperatures, are compared to available experimental data and other calculations. These comparisons indicate that the proposed potential has correct low density limit behavior and works well for plasma in a wide range of densities and temperatures, including warm dense matter.
Grain-scale strain heterogeneity as a function of crystallographic texture in phase-change electro-mechanical ceramics
Authors: Kong Scarlet , Daniels John
Published: November 2020

A reduction in the orientation distribution of grains, via crystallographic texturing, is known to significantly enhance the electro-mechanical response in polycrystalline piezoelectrics. Through calculations of the electric-field-induced strain in phase-changing ceramics, the local strain heterogeneity was also found to increase with crystallographic texture. The increase in grain-scale strain heterogeneity potentially indicates greater stress concentrations within the polycrystal and may degrade the expected lifetime and fatigue behavior in these ceramics. In crystallographic symmetries with higher numbers of polarization directions, it was found that the magnitude of heterogeneity in the response was lower.
High-speed droplet impingement on dry and wetted substrates
Authors: Marzbali Mason , Dolatabadi Ali
Published: November 2020

High-speed droplet impact is of great interest to power generation and aerospace industries due to the accrued cost of maintenance in steam and gas turbines. The repetitive impacts of liquid droplets onto rotor blades, at high relative velocities, result in blade erosion, which is known as liquid impingement erosion (LIE). Experimental and analytical studies in this field are limited due to the complexity of the droplet impact at such conditions. Hence, numerical analysis is a very powerful and affordable tool to investigate the LIE phenomenon. In this regard, it is crucial to understand the hydrodynamics of the impact in order to identify the consequent solid response before addressing the LIE problem. The numerical study of the droplet impingement provides the transient pressure history generated in the liquid. Determining the transient behavior of the substrate, in response to the pressure force exerted due to the droplet impact, would facilitate engineering new types of surface coatings that are more resistant to LIE. To that end, quantifying the impact pressure of compressible liquid droplets impinged at very high velocities, up to 500 m/s, on rigid solid substrates and liquid films is the main objective of the present work. A wide range of scenarios that commonly arise in the LIE problem are considered, i.e., droplet sizes between 200 µm and 1000 μm, impact velocities ranging from 100 m/s to 500 m/s, and liquid film thicknesses of 0 µm–200 μm. The maximum pressure exerted on the solid surface due to the droplet impact is calculated for both dry and wetted substrates. The results obtained from compressible fluid modeling are compared to those of other numerical studies and analytical correlations, available in the open literature. New correlations are developed for maximum impact pressure on rigid solids and liquid films that can be used to characterize the solid stress and estimate the lifetime of the material by carrying out the fatigue analysis.
The combined kinetic effects of the ion temperature gradient and the velocity shear of a plasma flow parallel to the magnetic field on the drift-Alfven instabilities
Authors: Mikhailenko V. V. , Mikhailenko V. S. , Lee H. J.
Published: November 2020

The drift-Alfvén instabilities of the sheared flow along the magnetic field of a finite beta (1>β≫me/mi) plasma with comparable inhomogeneous ion temperature and homogeneous electron temperature are examined by the numerical analysis of the derived linear dispersion equation. Accounting for the electromagnetic ion kinetic response, which has been neglected in conventional discussions of the drift-Alfvén instabilities of a steady plasma, a new kinetic drift-Alfvén instability has been found. It develops in a plasma shear flow due to the coupled action of the ion temperature gradient, the flow velocity shear, and the inverse ion Landau damping.
Beyond Born–Oppenheimer constructed diabatic potential energy surfaces for F + H2 reaction
Authors: Mukherjee Bijit , Naskar Koushik , Mukherjee Soumya , Ravi Satyam , Shamasundar K. R. , Mukhopadhyay Debasis , Adhikari Satrajit
Published: November 2020

First principles based beyond Born–Oppenheimer theory has been implemented on the F + H2 system for constructing multistate global diabatic Potential Energy Surfaces (PESs) through the incorporation of Nonadiabatic Coupling Terms (NACTs) explicitly. The spin–orbit (SO) coupling effect on the collision process of the F + H2 reaction has been included as a perturbation to the non-relativistic electronic Hamiltonian. Adiabatic PESs and NACTs for the lowest three electronic states (12A′, 22A′, and 12A″) are determined in hyperspherical coordinates as functions of hyperangles for a grid of fixed values of the hyperradius. Jahn–Teller (JT) type conical intersections between the two A′ states translate along C2v and linear geometries in F + H2. In addition, A′ and A″ states undergo Renner–Teller (RT) interaction at collinear configurations of this system. Both JT and RT couplings are validated by integrating NACTs along properly chosen contours. Subsequently, we have solved adiabatic-to-diabatic transformation (ADT) equations to evaluate the ADT angles for constructing the diabatic potential matrix of F + H2, including the SO coupling terms. The newly calculated diabatic PESs are found to be smooth, single-valued, continuous, and symmetric and can be invoked for performing accurate scattering calculations on the F + H2 system.
On the structure and patterns of von Kármán vortices in two-dimensional high Reynolds number flows
Authors: Lewis David R. , Radko Timour
Published: November 2020

This study explores the dynamics and statistical patterns of coherent long-lived vortices spontaneously forming in bluff body wakes. The analysis is based on a series of two-dimensional direct numerical simulations performed for a wide range of Reynolds numbers. We demonstrate that the majority of coherent vortices beyond the recirculation zone are well represented by the canonical Lamb–Oseen solution. This observation is used to develop a low-order census of long-lived eddies in terms of their core sizes and vorticity magnitudes. We demonstrate that the increase in the Reynolds number (Re) leads to the systematic reduction in the initial core radii (r0), whereas the core vorticity (ζ0) increases. These dependencies exhibit singular behavior in the inviscid limit (Re → ∞), which is captured by the proposed explicit relations for r0(Re) and ζ0(Re).
Excitation of the axisymmetric Alfvén eigenmodes by micro-turbulence
Authors: Marchenko V. S. , Reznik S. N.
Published: November 2020

Electrostatic, short-wavelength (kθρs>1, with ρs being the ion sound Larmor radius) micro-turbulence, which is present at the plasma edge due to its intrinsic immunity to equilibrium E × B shear suppression, can drive global, axisymmetric [n=0,m=±1, with n(m) being the toroidal (poloidal) mode number] Alfvén eigenmode (GAE) with the inertial layer located at the plasma edge, i.e., in the turbulent zone. The excitation mechanism is the modulation instability induced by turbulent Reynolds stress. The growth rate of this instability can overcome GAE continuum damping.
Improved walker population control for full configuration interaction quantum Monte Carlo
Authors: Yang Mingrui , Pahl Elke , Brand Joachim
Published: November 2020

Full configuration interaction quantum Monte Carlo (FCIQMC) is a stochastic approach for finding the ground state of a quantum many-body Hamiltonian. It is based on the dynamical evolution of a walker population in Hilbert space, which samples the ground state configuration vector over many iterations. Here, we present a modification of the original protocol for walker population control of Booth et al. [J. Chem. Phys. 131, 054106 (2009)] in order to achieve equilibration at a pre-defined average walker number and to avoid walker number overshoots. The dynamics of the walker population is described by a noisy damped harmonic oscillator and controlled by two parameters responsible for damping and forcing, respectively, for which reasonable values are suggested. We further introduce a population growth witness that can be used to detect annihilation plateaus related to overcoming the FCIQMC sign problem. Features of the new population control procedure such as precise walker number control and fast equilibration are demonstrated. The standard error of the shift estimator for the ground state energy as well as the population control bias is found to be unaffected by the population control procedure or its parameters. The improved control of the walker number, and thereby memory consumption, is a desirable feature required for automating FCIQMC calculations and requires minimal modifications to the existing code.
Semiclassical initial value representation: From Møller to Miller
Authors: Bonnet Laurent
Published: November 2020

The initial value representation (IVR) was proposed five decades ago by Miller [J. Chem. Phys. 53, 3578 (1970)] in order to improve the feasibility and accuracy of semiclassical (SC) scattering calculations. Møller operators, which play a fundamental role in quantum scattering theory, do not appear in his formulation based on action-angle coordinates. These operators were introduced much later by Garashchuk and Light [J. Chem. Phys. 114, 1060 (2001)] in SC-IVR calculations performed in Cartesian coordinates within the Tannor and Weeks [J. Chem. Phys. 98, 3884 (1993)] formulation of quantum scattering theory. Remarkably, Møller operators were found to boost the numerical efficiency of SC-IVR calculations. The purpose of this work is to show within a simple model of light-induced rotational transitions that, in fact, Møller operators were already underlying Miller’s pioneering formulation. In line with the results of Garashchuk and Light [J. Chem. Phys. 114, 1060 (2001)], removing the action of these operators in Miller’s theory strongly decreases its numerical efficiency.
Quantitative comparison of magnon transport experiments in three-terminal YIG/Pt nanostructures acquired via dc and ac detection techniques
Authors: Gückelhorn J. , Wimmer T. , Geprägs S. , Huebl H. , Gross R. , Althammer M.
Published: November 2020

All-electrical generation and detection of pure spin currents are promising ways toward controlling the diffusive magnon transport in magnetically ordered insulators. We quantitatively compare two measurement schemes, which allow us to measure the magnon spin transport in a three-terminal device based on a yttrium iron garnet thin film. We demonstrate that the dc charge current method based on the current reversal technique and the ac charge current method utilizing first and second harmonic lock-in detection can both efficiently distinguish between electrically and thermally injected magnons. In addition, both measurement schemes allow us to investigate the modulation of magnon transport induced by an additional dc charge current applied to the center modulator strip. However, while at a low modulator charge current both schemes yield identical results, we find clear differences above a certain threshold current. This difference originates from nonlinear effects of the modulator current on the magnon conductance.
Poiseuille number behavior in an adiabatically choked microchannel in the slip regime
Authors: Garg Richie , Agrawal Amit
Published: November 2020

The influence of subsonic adiabatic choking on frictional resistance inside three-dimensional (3D) microchannels has not been studied for rarefied gas flows. In the present work, the variation of the Poiseuille number with respect to the Mach number has been documented for a 3D microchannel of aspect ratio (width/height) 0.49. Measurements of mass flow rate, static pressure, and temperature have been conducted with nitrogen in highly compressible and slightly rarefied (slip flow) regime: outlet Mach number (0.43–0.99), outlet Knudsen number (4.04 × 10−3–7.04 × 10−3), and pressure ratio (8.17–8.72). The present 3D measurements are compared with available analytical solutions for isothermal and adiabatic flows. A maximum deviation of only 4.8% from the adiabatic slip flow solution points toward the adiabatic nature of the exit choked state, which is being experimentally demonstrated for the first time in the highly compressible slip flow regime. Furthermore, the influence of losses of microchannel end manifolds on the overall pressure drop is calculated to be negligible. We further propose the ranges of the area ratio, Reynolds number, and Knudsen number for which these losses continue to be unimportant for gaseous slip flow. This study gives insights into the influence of subsonic choking on the frictional resistance at various mass flow rates and is relevant for future space expeditions and in certain biological applications.
Artificial neural network-based nonlinear algebraic models for large eddy simulation of turbulence
Authors: Xie Chenyue , Yuan Zelong , Wang Jianchun
Published: November 2020

In this work, artificial neural network-based nonlinear algebraic models (ANN-NAMs) are developed for the subgrid-scale (SGS) stress in large eddy simulation (LES) of turbulence at the Taylor Reynolds number Reλ ranging from 180 to 250. An ANN architecture is applied to construct the coefficients of the general NAM for the SGS anisotropy stress. It is shown that the ANN-NAMs can reconstruct the SGS stress accurately in the a priori test. Furthermore, the ANN-NAMs are analyzed by calculating the average, root mean square values, and probability density functions of dimensionless model coefficients. In an a posteriori analysis, we compared the performance of the dynamic Smagorinsky model (DSM), dynamic mixed model (DMM), and ANN-NAM. The ANN-NAM yields good agreement with a filtered direct numerical simulation dataset for the spectrum, structure functions, and other statistics of velocity. Besides, the ANN-NAM predicts the instantaneous spatial structures of SGS anisotropy stress much better than the DSM and DMM. The NAM based on the ANN is a promising approach to deepen our understanding of SGS modeling in LES of turbulence.
Multiphysics flow simulations using D3Q19 lattice Boltzmann methods based on central moments
Authors: De Rosis Alessandro , Coreixas Christophe
Published: November 2020

In a recent work [A. De Rosis, R. Huang, and C. Coreixas, “Universal formulation of central-moments-based lattice Boltzmann method with external forcing for the simulation of multiphysics phenomena,” Phys. Fluids 31, 117102 (2019)], a multiple-relaxation-time lattice Boltzmann method (LBM) has been proposed by means of the D3Q27 discretization, where the collision stage is performed in the space of central moments (CMs). These quantities relax toward an elegant Galilean invariant equilibrium and can also include the effect of external accelerations. Here, we investigate the possibility to adopt a coarser lattice composed of 19 discrete velocities only. The consequences of such a choice are evaluated in terms of accuracy and stability through multiphysics benchmark problems based on single-, multi-phase, and magnetohydrodynamics flow simulations. In the end, it is shown that the reduction from 27 to 19 discrete velocities has only little impact on the accuracy and stability of the CM-LBM for moderate Reynolds number flows in the weakly compressible regime.
On the definitions and simulations of vibrational heat transport in nanojunctions
Authors: Kalantar Na’im , Agarwalla Bijay Kumar , Segal Dvira
Published: November 2020

Thermal transport through nanosystems is central to numerous processes in chemistry, material sciences, and electrical and mechanical engineering, with classical molecular dynamics as the key simulation tool. Here, we focus on thermal junctions with a molecule bridging two solids that are maintained at different temperatures. The classical steady state heat current in this system can be simulated in different ways, either at the interfaces with the solids, which are represented by thermostats, or between atoms within the conducting molecule. We show that while the latter, intramolecular definition feasibly converges to the correct limit, the molecule–thermostat interface definition is more challenging to converge to the correct result. The problem with the interface definition is demonstrated by simulating heat transport in harmonic and anharmonic one-dimensional chains illustrating unphysical effects such as thermal rectification in harmonic junctions.
Field enhancement in microfluidic semiconductor nanowire array
Authors: Shenoy Bhamy Maithry , Hegde Gopalkrishna , Roy Mahapatra D.
Published: November 2020

Nano-material integrated microfluidic platforms are increasingly being considered to accelerate biological sample preparation and molecular diagnostics. A major challenge in this context is the generation of high electric fields for electroporation of cell membranes. In this paper, we have studied a novel mechanism of generating a high electric field in the microfluidic channels by using an array of semiconductor nanowires. When an electrostatic field is applied across a semiconductor nanowire array, the electric field is localized near the nanowires and the field strength is higher than what was reported previously with various other micro-geometries. Nanowires made of ZnO, Si, and Si–SiO2 and their orientation and array spacing are considered design parameters. It is observed that for a given ratio of the spacing between nanowires to the diameter, the electric field enhancement near the edges of ZnO nanowires is nearly 30 times higher compared to Si or Si–SiO2 nanowire arrays. This enhancement is a combined effect of the unique geometry with a pointed tip with a hexagonal cross section, the piezoelectric and the spontaneous polarization in the ZnO nanowires, and the electro-kinetics of the interface fluid. Considering the field localization phenomena, the trajectories of E. coli cells in the channel are analyzed. For a given inter-nanowire spacing and an applied electric field, the channels with ZnO nanowire arrays have a greater probability of cell lysis in comparison to Si-based nanowire arrays. Detailed correlations between the cell lysis probability with the inter-nanowire spacing and the applied electric field are reported.
Coronavirus rotational diffusivity
Authors: Kanso M. A. , Piette J. H. , Hanna J. A. , Giacomin A. J.
Published: November 2020

Just 11 weeks after the confirmation of first infection, one team had already discovered and published [D. Wrapp et al., “Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation,” Science 367(6483), 1260–1263 (2020)] in exquisite detail about the new coronavirus, along with how it differs from previous viruses. We call the virus particle causing the COVID-19 disease SARS-CoV-2, a spherical capsid covered with spikes termed peplomers. Since the virus is not motile, it relies on its own random thermal motion, specifically the rotational component of this thermal motion, to align its peplomers with targets. The governing transport property for the virus to attack successfully is thus the rotational diffusivity. Too little rotational diffusivity and too few alignments are produced to properly infect. Too much, and the alignment intervals will be too short to properly infect, and the peplomer is wasted. In this paper, we calculate the rotational diffusivity along with the complex viscosity of four classes of virus particles of ascending geometric complexity: tobacco mosaic, gemini, adeno, and corona. The gemini and adeno viruses share icosahedral bead arrangements, and for the corona virus, we use polyhedral solutions to the Thomson problem to arrange its peplomers. We employ general rigid bead–rod theory to calculate complex viscosities and rotational diffusivities, from first principles, of the virus suspensions. We find that our ab initio calculations agree with the observed complex viscosity of the tobacco mosaic virus suspension. From our analysis of the gemini virus suspension, we learn that the fine detail of the virus structure governs its rotational diffusivity. We find the characteristic time for the adenovirus from general rigid bead–rod theory. Finally, from our analysis of the coronavirus suspension, we learn that its rotational diffusivity descends monotonically with its number of peplomers.
Visualisation of diffusion sites and measurement of hydrogen traps in hot-rolled pipes
Authors: Thomas Alen , Szpunar Jerzy A.
Published: November 2020

Inclusions are very often founded in the centre of thickness in hot-rolled pipeline steel. In this research, the role of these inclusions on hydrogen diffusion, accumulation and distribution in pipeline steel is studied using the electrochemical permeation and visualisation experiments. While the permeation experiment estimates the parameters of the diffusion process, the visualisation experiment reveals the diffusion pathway in the steel microstructure. Results from the permeation test allowed to show that the steel samples selected from the segregation zone at the mid-layer of thickness have higher permeability and effective diffusion coefficient than samples from the top-layer. Also, the hydrogen visualisation results permit to reveal an increased discharge of hydrogen around inclusions as represented by a pattern of superimposed white particles. Moreover, the calculated diffusion parameters also allowed us to establish that the density of hydrogen traps in mid-layer was lower than top-layer of the steel.
Influence of countermovement depth on the countermovement jump‐derived reactive strength index modified
Authors: Pérez‐Castilla Alejandro , Weakley Jonathon , García‐Pinillos Felipe , Rojas F. Javier , García‐Ramos Amador
Published: November 2020

This study aimed to investigate the effect of countermovement depth on the magnitude of the countermovement jump (CMJ) derived reactive strength index modified (RSImod), and to compare the RSImod between the CMJ performed with a self‐preferred knee flexion angle (CMJpref) and the CMJ performed from a pre‐determined knee flexion angle (CMJrefer) with the countermovement depth more similar to the CMJpref. Sixteen subjects (11 males and 5 females; age 25.1 ± 6.3 years, body mass 69.7 ± 10.2 kg, body height 172.9 ± 8.1 m) randomly performed in a single session the CMJpref and CMJs from five pre‐determined knee flexion angles (60°, 75°, 90°, 105°, and 120°). Our results showed that lower knee flexion angles were generally associated with greater RSImod values with the CMJ performed at 60° showing the greatest RSImod (P ≤ 0.049; effect size [ES] range = 0.19–0.63). The greatest RSImod for the CMJ performed at 60° was caused by the proportionally lower values of the time to take‐off (ES range = 0.65–1.91) compared to the decrease observed in jump height (ES range = 0.11–0.25). The RSImod was higher for the CMJpref compared to the CMJrefer (P < 0.001; ES = 0.34) due to a higher jump height (P = 0.021; ES = 0.14) and reduced time to take‐off (P < 0.001; ES = 0.85). These results indicate that practitioners should be careful when interpreting an individual's changes in RSImod when the countermovement depth is not similar across the testing sessions. However, since the use of pre‐determined knee flexion angles negatively impacts the RSImod, we encourage practitioners to use the CMJpref but only compare the RSImod when CMJs are performed using consistent countermovement depths.
Delayed potentiation effects on neuromuscular performance after optimal load and high load resistance priming sessions using velocity loss
Authors: González‐García Jaime , Giráldez‐Costas Verónica , Ruiz‐Moreno Carlos , Gutiérrez‐Hellín Jorge , Romero‐Moraleda Blanca
Published: November 2020

Aim: (i) to compare the effects of two different low‐volume resistance priming sessions, where the external load is modified on neuromuscular performance after 6 h of rest; and (ii) to identify the effects on psychological readiness in participants with resistance training experience. Methods: Eleven participants (Body mass: 77.0 ± 8.9 kg; Body height: 1.76 ± 0.08 m; Half squat repetition maximum: 139.8 ± 22.4 kg) performed the priming session under three experimental conditions in a randomized and cross‐over design during the morning. The control (CON) condition: no resistance training, “optimal load” (OL) condition: two half‐squat sets with a velocity loss of around 20% were performed with the “optimal load”, and 80% of repetition maximum (80% RM) condition: 2 half‐squat sets with a velocity loss of around 20% were performed with the 80% RM. Countermovement jump (CMJ), mean power with OL (MPOL) and 80% RM (MP80RM), and mean velocity with OL (MVOL) and 80% RM (MV80RM) were assessed six hours after the intervention. Subjective readiness was also recorded prior to resistance training and evaluation. Significance was set at p < 0.05. Results: CMJ was higher after the 80% RM intervention than CON (p < 0.001; Δ = 6.5% [3.4–9.5]). MPOL and MVOL seemed to be unaffected by both morning sessions. Higher MP80RM (p = 0.044; Δ = 9.7% [4.0–15.6]; d = 0.24[0.10–0.37]) and MV80RM (p = 0.004; Δ = 8.1% [3.2–13.3]; d = 0.32[0.13–0.52]) after 80% RM than after CON were observed. No effect was observed on psychological readiness. Conclusions: 80% RM priming session increased CMJ height and the capacity to generate power and velocity under a high‐load condition without any effect on psychological readiness.
Multi-sensor signal fusion for a compound fault diagnosis method with strong generalization and noise-tolerant performance
Authors: Wu Peilan , Nie Xiaoyin , Xie Gang
Published: November 2020

The gearbox is one of the main components of rotating machinery, for which the complex and changeable working environment leads to frequent failures. To solve the problems of the low diagnostic accuracy of compound faults, weak generalization ability, and difficult diagnosis in a noisy environment, a new method is proposed based on a convolutional neural network. First, the fusion of vibration signals collected by multiple sensors forms a one-dimensional sequence as the input of the network. Second, the random destruction of input and minimal batch normalization mechanisms are introduced to improve the
noise tolerance and generalization ability of the model. Finally, the accuracy is estimated by ten-fold cross-validation, which ensures the reliability of the diagnostic results when there are few fault samples. The resulting method is used in compound fault diagnosis under different working conditions. The results show that the method has an accuracy rate of more than 99.5% for gearbox compound-fault classification, strong generalization, and good noise-tolerant performance.
High-bandwidth light inputting multilevel photoelectric memory based on thin-film transistor with a floating gate of CsPbBr3/CsPbI3 blend quantum dots
Authors: Pei Junxiang , Wu Xiaohan , Huo Jingyong , Liu Wen-Jun , Zhang David Wei , Ding Shi-Jin
Published: November 2020

The electronic-photonic convergent systems can overcome the data transmission bottleneck for microchips by enabling processor and memory chips with high-bandwidth optical input/output. However, current silicon-based electronic-photonic systems require various functional devices/components to convert high-bandwidth optical signals into electrical ones, thus making further integrations of sophisticated systems rather difficult. Here, we demonstrate thin-film transistor-based photoelectric memories employing CsPbBr3/CsPbI3 blend perovskite quantum dots (PQDs) as a floating gate, and multilevel memory cells are achieved under programming and erasing modes, respectively, by imputing high-bandwidth optical signals. For different bandwidth light input (i.e. 500–550, 575–650 and 675–750 nm) with the same intensity, three levels of programming window (i.e. 3.7, 1.9 and 0.8 V) and erasing window (i.e. −1.9, −0.6 and −0.1 V) are obtained under electrical pulses, respectively. This is because the blend PQDs have two different bandgaps, and different amounts of photo-generated carriers can be produced for different wavelength optical inputs. It is noticed that the 675–750 nm light inputs have no effects on both programming and erasing windows because of no photo-carriers generation. Four memory states are demonstrated, showing enough large gaps (1.12–5.61 V) between each other, good data retention and programming/erasing endurance. By inputting different optical signals, different memory states can be switched easily. Therefore, this work directly demonstrates high-bandwidth light inputting multilevel memory cells for novel electronic-photonic systems.
Monte Carlo calculation of the relative TG-43 dosimetry parameters for the INTRABEAM electronic brachytherapy source
Authors: Ayala Alvarez David Santiago , G F Watson Peter , Popovic Marija , Jean Heng Veng , Evans Michael D C , Seuntjens Jan
Published: November 2020

The INTRABEAM system (Carl Zeiss Meditec AG, Jena, Germany) is an electronic brachytherapy (eBT) device designed for intraoperative radiotherapy applications. To date, the INTRABEAM x-ray source has not been characterized according to the AAPM TG-43 specifications for brachytherapy sources. This restricts its modelling in commercial treatment planning systems (TPSs), with the consequence that the doses to organs at risk are unknown. The aim of this work is to characterize the INTRABEAM source according to the TG-43 brachytherapy dosimetry protocol. The dose distribution in water around the source was determined with Monte Carlo (MC) calculations. For the validation of the MC model, depth dose calculations along the source longitudinal axis were compared with measurements using a soft x-ray ionization chamber (PTW 34013) and two synthetic diamond detectors (microDiamond PTW TN60019). In our results, the measurements in water agreed with the MC model calculations within uncertainties. The use of the microDiamond detector yielded better agreement with MC calculations, within estimated uncertainties, compared to the ionization chamber at points of steeper dose gradients. The radial dose function showed a steep fall-off close to the INTRABEAM source (

<

10 mm) with a gradient higher than that of commonly used brachytherapy radionuclides (192Ir, 125I and 103Pd), with values of 2.510, 1.645 and 1.232 at 4, 6 and 8 mm, respectively. The radial dose function partially flattens at larger distances with a fall-off comparable to that of the Xoft Axxent® (iCAD, Inc., Nashua, NH) eBT system. The simulated 2D polar anisotropy close to the bare probe walls showed deviations from unity of up to 55% at 10 mm and 155°. This work presents the MC calculated TG-43 parameters for the INTRABEAM, which constitute the necessary data for the characterization of the source as required by a TPS used in clinical dose calculations.
Mode competition in broad-ridge-waveguide lasers
Authors: Koester J-P , Putz A , Wenzel H , Wünsche H-J , Radziunas M , Stephan H , Wilkens M , Zeghuzi A , Knigge A
Published: November 2020

The lateral brightness achievable with high-power GaAs-based laser diodes having long and broad waveguides is commonly regarded to be limited by the onset of higher-order lateral modes. For the study of the lateral-mode competition two complementary simulation tools are applied, representing different classes of approximations. The first tool bases on a completely incoherent superposition of mode intensities and disregards longitudinal effects like spatial hole burning, whereas the second tool relies on a simplified carrier transport and current flow. Both tools yield agreeing power-current characteristics that fit the data measured for 5–23 µm wide ridges. Also, a similarly good qualitative conformance of the near and far fields is found. However, the threshold of individual modes, the partition of power between them at a given current, and details of the near and far fields show differences. These differences are the consequence of a high sensitivity of the mode competition to details of the models and of the device structure. Nevertheless, it can be concluded concordantly that the brightness rises with increasing ridge width irrespective of the onset of more and more lateral modes. The lateral brightness

2
 

W

 

mm

−
1

mrad

−
1

at 10 MW cm−2 power density on the front facet of the investigated laser with widest ridge (23 µm) is comparable with best values known from much wider broad-area lasers. In addition, we show that one of the simulation tools is able to predict beam steering and coherent beam coupling without introducing any phenomenological coupling coefficient or asymmetries.
Machine learning on the electron–boson mechanism in superconductors
Authors: Li Wan-Ju , Hsu Ming-Chien , Huang Shin-Ming
Published: November 2020

To unravel pairing mechanism of a superconductor from limited, indirect experimental data is always a difficult task. It is common but sometimes dubious to explain by a theoretical model with some tuning parameters. In this work, we propose that the machine learning might infer pairing mechanism from observables like superconducting gap functions. For superconductivity within the Migdal–Eliashberg theory, we perform supervised learning between superconducting gap functions and electron–boson spectral functions. For simple spectral functions, the neural network can easily capture the correspondence and predict perfectly. For complex spectral functions, an autoencoder is utilized to reduce the complexity of the spectral functions to be compatible to that of the gap functions. After this complexity-reduction process, relevant information of the spectral function is extracted and good performance restores. Our proposed method can extract relevant information from data and can be applied to general function-to-function mappings with asymmetric complexities either in physics or other fields.
Jamming of multiple persistent random walkers in arbitrary spatial dimension
Authors: Metson M J , Evans M R , Blythe R A
Published: November 2020

We consider the persistent exclusion process in which a set of persistent random walkers interact via hard-core exclusion on a hypercubic lattice inddimensions. We work within the ballistic regime whereby particles continue to hop in the same direction over many lattice sites before reorienting. In the case of two particles, we find the mean first-passage time to a jammed state where the particles occupy adjacent sites and face each other. This is achieved within an approximation that amounts to embedding the one-dimensional system in a higher-dimensional reservoir. Numerical results demonstrate the validity of this approximation, even for small lattices. The results admit a straightforward generalization to dilute systems comprising more than two particles. A self-consistency condition on the validity of these results suggest that clusters may form at arbitrarily low densities in the ballistic regime, in contrast to what has been found in the diffusive limit.
In and around abelian anyon models
*
Authors: Wang Liang , Wang Zhenghan
Published: November 2020

Anyon models are algebraic structures that model universal topological properties in topological phases of matter and can be regarded as mathematical characterization of topological order in two spacial dimensions. It is conjectured that every anyon model, or mathematically unitary modular tensor category, can be realized as the representation category of some chiral conformal field theory, or mathematically vertex operator algebra/local conformal net. This conjecture is known to be true for abelian anyon models providing support for the conjecture. We reexamine abelian anyon models from several different angles. First anyon models are algebraic data for both topological quantum field theories and chiral conformal field theories. While it is known that each abelian anyon model can be realized by a quantum abelian Chern–Simons (CS) theory and chiral conformal field theory, the construction is not algorithmic. Our goal is to provide such an explicit algorithm for a K-matrix in CS theory and a positive definite even one for a lattice conformal field theory. Secondly anyon models and chiral conformal field theories underlie the bulk-edge correspondence for topological phases of matter. But there are interesting subtleties in this correspondence when stability of the edge theory and topological symmetry are taken into consideration. Therefore, our focus is on the algorithmic reconstruction of extremal chiral conformal field theories with small central charges. Finally we conjecture that a much stronger reconstruction holds for abelian anyon models: every abelian anyon model can be realized as the representation category of some non-lattice extremal vertex operator algebra generalizing the moonshine realization of the trivial anyon model.
Dirac cones for bi- and trilayer Bernal-stacked graphene in a quantum graph model
Authors: de Oliveira César R , Rocha Vinícius L
Published: November 2020

A quantum graph model for a single sheet of graphene is extended to bilayer and trilayer Bernal-stacked graphene; the spectra are characterized and the dispersion relations explicitly obtained; Dirac cones are then proven to be present only for trilayer graphene, although the bilayer has a gapless parabolic band component. Our model rigorously exhibits basic facts from tight-binding calculations, effective two-dimensional models and a π-orbital continuum model with nearest-neighbour tunnelling that have been discussed in the physics literature.