bluuebunny/crossref_metadata_2025 huggingface dataset:
Examining fundamental and excitation gaps at the thermodynamic limit: A combined (QTP) DFT and coupled cluster study on trans-polyacetylene and polyacene
Authors: Windom Zachary W. , Perera Ajith , Bartlett Rodney J.
Published: May 2022

Interest in ab initio property prediction of π-conjugated polymers for technological applications places significant demand on “cost-effective” and conceptual computational methods, particularly effective, one-particle theories. This is particularly relevant in the case of Kohn–Sham Density Functional Theory (KS-DFT) and its new competitors that arise from correlated orbital theory, the latter defining the QTP family of DFT functionals. This study presents large, ab initio equation of motion-coupled cluster calculations using the massively parallel ACESIII to target the fundamental bandgap of two prototypical organic polymers, trans-polyacetylene (tPA) and polyacene (Ac), and provides an assessment of the new quantum theory project (QTP) functionals for this problem. Further results focusing on the 1Ag (1Ag), 1Bu (1B2u), and 3Bu (3B2u) excited states of tPA (Ac) are also presented. By performing calculations on oligomers of increasing size, extrapolations to the thermodynamic limit for the fundamental and all excitation gaps, as well as estimations of the exciton binding energy, are made. Thermodynamic-limit results for a combination of “optimal” and model geometries are presented. Calculated results for excitations that are adequately described using a single-particle model illustrate the benefits of requiring a KS-DFT functional to satisfy the Bartlett ionization potential theorem.
Type-Y magnetic tunnel junctions with CoFeB doped tungsten as spin current source
Authors: Zhao M. K. , Zhang R. , Wan C. H. , Luo X. M. , Zhang Y. , He W. Q. , Wang Y. Z. , Yang W. L. , Yu G. Q. , Han X. F.
Published: May 2022

Spin–orbit torque magnetic tunnel junctions (SOT-MTJs) with high tunneling magnetoresistance (TMR) ratio and high energy-efficiency are crucial for the development of SOT-magnetic random-access memory and other SOT devices. Here, the SOT-MTJs doped with an ultrathin layer of 0.2 nm CoFeB in the W writing line are fabricated, and the TMR ratio of the updated MTJs is up to 179%. Meanwhile, the SOT efficiency of the W layer doped with magnetic atoms (∼0.149) is weakly dependent on the doping, manifesting the intrinsic mechanism of the W layer in generating the spin Hall effect. This study shows promise of the magnetic-atom doped W/CoFeB/MgO/synthetic antiferromagnetic stacks to achieve high TMR and efficient type-Y SOT devices.
Imaging dynamic exciton interactions and coupling in transition metal dichalcogenides
Authors: Purz Torben L. , Martin Eric W. , Holtzmann William G. , Rivera Pasqual , Alfrey Adam , Bates Kelsey M. , Deng Hui , Xu Xiaodong , Cundiff Steven T.
Published: May 2022

Transition metal dichalcogenides (TMDs) are regarded as a possible material platform for quantum information science and related device applications. In TMD monolayers, the dephasing time and inhomogeneity are crucial parameters for any quantum information application. In TMD heterostructures, coupling strength and interlayer exciton lifetimes are also parameters of interest. However, many demonstrations in TMDs can only be realized at specific spots on the sample, presenting a challenge to the scalability of these applications. Here, using multi-dimensional coherent imaging spectroscopy, we shed light on the underlying physics—including dephasing, inhomogeneity, and strain—for a MoSe2 monolayer and identify both promising and unfavorable areas for quantum information applications. We, furthermore, apply the same technique to a MoSe2/WSe2 heterostructure. Despite the notable presence of strain and dielectric environment changes, coherent and incoherent coupling and interlayer exciton lifetimes are mostly robust across the sample. This uniformity is despite a significantly inhomogeneous interlayer exciton photoluminescence distribution that suggests a bad sample for device applications. This robustness strengthens the case for TMDs as a next-generation material platform in quantum information science and beyond.
Controlling energy conservation in quantum dynamics with independently moving basis functions: Application to multi-configuration Ehrenfest
Authors: Asaad Mina , Joubert-Doriol Loïc , Izmaylov Artur F.
Published: May 2022

Application of the time-dependent variational principle to a linear combination of frozen-width Gaussians describing the nuclear wavefunction provides a formalism where the total energy is conserved. The computational downside of this formalism is that trajectories of individual Gaussians are solutions of a coupled system of differential equations, limiting implementation to serial propagation algorithms. To allow for parallelization and acceleration of the computation, independent trajectories based on simplified equations of motion were suggested. Unfortunately, within practical realizations involving finite Gaussian bases, this simplification leads to breaking the energy conservation. We offer a solution for this problem by using Lagrange multipliers to ensure the energy and norm conservation regardless of basis function trajectories or basis completeness. We illustrate our approach within the multi-configurational Ehrenfest method considering a linear vibronic coupling model.
Sequential snapping and pathways in a mechanical metamaterial
Authors: Ding Jiangnan , van Hecke Martin
Published: May 2022

Materials that feature bistable elements, hysterons, exhibit memory effects. Often, these hysterons are difficult to observe or control directly. Here, we introduce a mechanical metamaterial in which slender elements, interacting with pushers, act as mechanical hysterons. We show how we can tune the hysteron properties and pathways under cyclic compression by the geometric design of these elements and how we can tune the pathways of a given sample by tilting one of the boundaries. Furthermore, we investigate the effect of the coupling of a global shear mode to the hysterons as an example of the interactions between hysteron and non-hysteron degrees of freedom. We hope our work will inspire further studies on designer matter with targeted pathways.
Wafer-scale low-disorder 2DEG in 28Si/SiGe without an epitaxial Si cap
Authors: Degli Esposti Davide , Paquelet Wuetz Brian , Fezzi Viviana , Lodari Mario , Sammak Amir , Scappucci Giordano
Published: May 2022

We grow 28Si/SiGe heterostructures by reduced-pressure chemical vapor deposition and terminate the stack without an epitaxial Si cap but with an amorphous Si-rich layer obtained by exposing the SiGe barrier to dichlorosilane at 500 °C. As a result, 28Si/SiGe heterostructure field-effect transistors feature a sharp semiconductor/dielectric interface and support a two-dimensional electron gas with enhanced and more uniform transport properties across a 100 mm wafer. At T = 1.7 K, we measure a high mean mobility of (1.8±0.5)×105 cm2/V s and a low mean percolation density of (9±1)×1010 cm−2. From the analysis of Shubnikov–de Haas oscillations at T = 190 mK, we obtain a long mean single particle relaxation time of (8.1±0.5) ps, corresponding to a mean quantum mobility and quantum level broadening of (7.5±0.6)×104 cm2/V s and (40±3) μeV, respectively, and a small mean Dingle ratio of (2.3±0.2), indicating reduced scattering from long range impurities and a low-disorder environment for hosting high-performance spin-qubits.
Analytical simulation of normal shock waves in turbulent flow
Authors: Avramenko Andriy A. , Tyrinov Andrii I. , Shevchuk Igor V.
Published: May 2022

The focus of the work is on analytical modeling of normal shock wave propagation in a turbulent adiabatic gas flow. For this, a modified Rankine–Hugoniot model was developed. A solution is obtained for the Rankine–Hugoniot conditions in a turbulent gas flow with different turbulence intensity. Variation of the velocity of an adiabatic turbulent gas flow during its passage through a normal shock wave is elucidated depending on the turbulence intensity. The equation of the modified Hugoniot adiabat is also obtained.
Finite-temperature atomic relaxations: Effect on the temperature-dependent C44 elastic constants of Si and BAs
Authors: Malica Cristiano , Dal Corso Andrea
Published: May 2022

The effect of atomic relaxations on the temperature-dependent elastic constants (TDECs) is usually taken into account at zero temperature by the minimization of the total energy at each strain. In this paper, we investigate the order of magnitude of this approximation on a paradigmatic example: the C44 elastic constant of diamond and zincblende materials. We estimate the effect of finite-temperature atomic relaxations within the quasi-harmonic approximation by computing ab initio the internal strain tensor from the second derivatives of the Helmholtz free-energy with respect to strain and atomic displacements. We apply our approach to Si and BAs and find a visible difference between the softening of the TDECs computed with the zero-temperature and finite-temperature atomic relaxations. In Si, the softening of C44 passes from 8.6% to 4.5%, between T = 0 K and T = 1200 K. In BAs, it passes from 8% to 7%, in the same range of temperatures. Finally, from the computed elastic constant corrections, we derive the temperature-dependent Kleinman parameter, which is usually measured in experiments.
Quantifying and mitigating soiling and abrasion in solar power
Authors: Kleissl Jan
Published: May 2022

Countries with some of the best solar resources suffer disproportionately from soiling and abrasion, which reduces system conversion efficiencies and decreases equipment lifetime. This Special Collection covers climatological analyses, soiling metrology, best installation practices to reduce soiling and abrasion, and improvements to equipment and materials to mitigate soiling and abrasion.
Industrial risks by the coast: how people-place bonds impact acceptance of a red mud recycling project (Riesgos industriales en la costa: cómo afectan los lazos persona-lugar a la aceptación de un proyecto de reciclaje de lodo rojo)
Authors: Bertoldo Raquel , Berrhoun Thomas , Merdy Patricia
Published: May 2022

Industries sometimes leaves invisible yet dangerous chemical memories of their activities. Because these compounds are invisible, people rely on heuristics informed in part by people-place relations to make a risk judgment. The Marseille region of France provides an interesting case to analyse how local risks are judged in relation to people-place variables. The perceived risks of a depollution project where ‘red mud’ (an industrial residue) is used to neutralize lead-contaminated soil are analysed in relation to (1) place attachment and (2) trust in several types of organization. Results show that participants with stronger local attachment perceive their local environment as less polluted and consider the project as a greater threat. Furthermore, risks vs. benefits associated with the project are significantly explained by age (associated with perceived risk) and trust in societal organizations (associated with perceived benefits). Discussion considers how the diversity of local publics could lead to widely different reactions to the depollution project across the city’s social tissue.
Aspects of three-dimensional higher curvature gravities
Authors: Bueno Pablo , Cano Pablo A , Llorens Quim , Moreno Javier , van der Velde Guido
Published: May 2022

We present new results involving general higher-curvature gravities in three dimensions. The most general Lagrangian of that kind can be written as a function of

R
,

S

2

,

S

3

, where R is the Ricci scalar,

S

2

≡

R

~

a

b

R

~

b

a

,

S

3

≡

R

~

a

b

R

~

b

c

R

~

c

a

, and

R

~

a
b

is the traceless part of the Ricci tensor. First, we provide a general formula for the exact number of independent order-n densities, #(n). This satisfies the identity #(n − 6) = #(n) − n. Then, we show that, linearized around a general Einstein solution, a generic order-n ⩾ 2 density can be written as a linear combination of R

n
, which by itself would not propagate the generic massive graviton, plus a density which by itself would not propagate the generic scalar mode,

R

n

−
12
n

(

n
−
1

)

R

n
−
2

S

2

, plus #(n) − 2 densities which contribute trivially to the linearized equations. Next, we obtain an analytic formula for the quasinormal modes and frequencies of the BTZ black hole as a function of the masses of the graviton and scalar modes for a general theory. Then, we provide a recursive formula as well as a general closed expression for order-n densities which non-trivially satisfy an holographic c-theorem, clarify their relation with Born–Infeld gravities and prove that the scalar mode is always absent from their spectrum. We show that, at each order n ⩾ 6, there exist #(n − 6) densities which satisfy the holographic c-theorem in a trivial way and that all of them are proportional to a single sextic density

Ω

(

6

)

≡
6

S

3

2

−

S

2

3

. Next, we show that there are also #(n − 6) order-n generalized quasi-topological densities in three dimensions, all of which are ‘trivial’ in the sense of making no contribution to the metric function equation. Remarkably, the set of such densities turns out to coincide exactly with the one of theories trivially satisfying the holographic c-theorem. We comment on the meaning of Ω(6) and its relation to the Segre classification of three-dimensional metrics.
Analysis of size dependence and the behavior under ultrahigh current density injection condition of GaN-based Micro-LEDs with pixel size down to 3 μm
Authors: Liu Yibo , Feng Feng , Zhang Ke , Jiang Fulong , Chan Ka-Wah , Kwok Hoi-Sing , Liu Zhaojun
Published: May 2022

In this paper, the GaN-based green micro light-emitting diodes (Micro-LEDs) with various sizes (from 3 to 100 μm) were fabricated and electro-optically characterized. Atom layer deposition (ALD) passivation and potassium hydroxide (KOH) treatment were applied to eliminate the sidewall damage. The size dependence of Micro-LED was systematically analyzed with current-versus-voltage and current density-versus-voltage relationship. According to the favorable ideality factor results (<1.5), the optimized sidewall treatment was achieved when the device size shrank down to <10 μm. In addition, the external quantum efficiency (EQE) droop phenomenon, luminance and output power density characteristics were depicted up to the highest current density injection condition to date (120 kA cm−2), and 6 μm device exhibited an improved EQE performance with the peak EQE value of 16.59% at 20 A cm−2 and over 600k and 6M cd cm−2 at 1 and 10 A cm−2, indicating a greater brightness quality for over 3000 PPI multiple display application. Lastly, the blue shift of 6 μm device with elevating current density was observed in electroluminescence spectra and converted to CIE 1931 color space. The whole shifting track and color variation from 1 A cm−2 to 120 kA cm−2 were demonstrated by color coordinates.
Discussion on the mechanism leading to positive synergism in SF6 mixtures with HFO1234ze(E)
Authors: Egüz E A , Pachin J , Franck C M
Published: May 2022

The electric strength in HFO1234ze(E)/SF6 mixtures is investigated with swarm and breakdown experiments. The density-reduced critical electric field as well as the breakdown voltage measured with both techniques, are found to be higher than that of the pure gases in mixtures with more than 10% SF6. The underlying mechanism for the observed positive synergy is investigated and the explanation proposed by Hunter and Christophorou (1985 J. Appl. Phys.
57 4377–85) is discussed for this mixture. The pressure-dependent attachment rate is found to increase with SF6 ratio thus satisfying the main requirement of the proposed mechanism in Hunter and Christophorou’s study. It appears nevertheless that due to the fast saturation with pressure and low rates in the mixtures, the three-body attachment processes account only for a small increase in the electric strength. An alternative hypothesis is proposed which considers the strong reduction of electron energies via inelastic processes in HFO1234ze(E), and is qualitatively demonstrated based on measurements and simulations.
Intermolecular interaction and cooperativity in an Fe(II) spin crossover molecular thin film system
Authors: Hao Guanhua , Dale Ashley S , N’Diaye Alpha T , Chopdekar Rajesh V , Koch Roland J , Jiang Xuanyuan , Mellinger Corbyn , Zhang Jian , Cheng Ruihua , Xu Xiaoshan , Dowben Peter A
Published: May 2022

Compact domain features have been observed in spin crossover [Fe{H2B(pz)2}2(bipy)] molecular thin film systems via soft x-ray absorption spectroscopy and photoemission electron microscopy. The domains are in a mixed spin state that on average corresponds to roughly 2/3 the high spin occupation of the pure high spin state. Monte Carlo simulations support the presence of intermolecular interactions that can be described in terms of an Ising model in which interactions beyond nearest-neighbors cannot be neglected. This suggests the presence of short-range order to permit interactions between molecules beyond nearest neighbor that contribute to the formation of largely high spin state domains structure. The formation of a spin state domain structure appears to be the result of extensive cooperative effects.
Terahertz transverse electric modes in graphene with DC current in hydrodynamic regime
Authors: Moiseenko I M , Popov V V , Fateev D V
Published: May 2022

The dispersion, excitation, and amplification of electromagnetic transverse electric (TE) modes at terahertz (THz) frequencies in graphene in the hydrodynamic (HD) regime, with a direct electric current flowing perpendicular to the TE mode wavevector, were theoretically investigated. The expression for the nonlocal HD conductivity of graphene with a direct electric current flowing perpendicular to the TE mode wavevector was derived. The direct electric current in graphene leads to the capacitive nature of the graphene HD conductivity at THz frequencies, which makes TE modes exist in this frequency range. The excitation of TE modes in graphene by an incident THz wave was modeled for the attenuated total reflection geometry. A new physical mechanism of TE mode amplification in graphene effective for a low value of carrier drift velocity was predicted. THz lasing regimes with TE modes in graphene structure with direct electric current were found. The results of this work can be used to create miniature technologically feasible sources and amplifiers of THz radiation.
Higher Chern number states in curved periodic nanowires
Authors: Siu Zhuo Bin , Tan Seng Ghee , Jalil Mansoor B A
Published: May 2022

The coupling between the spin and momentum degrees of freedom due to spin–orbit interactions (SOI) suggests that the strength of the latter can be modified by controlling the motion of the charge carriers. In this paper, we investigate how the effective SOI can be modulated by constraining the motion of charge carriers to curved waveguides thereby introducing real-space geometric curvature in their motion. The change in the SOI can in turn induce topological phase transitions in the system. Specifically, we study how the introduction of periodic sinusoidal curvature in nanowires with intrinsic SOC can induce the onset of mid-gap topologically protected edge states, which can be characterized by a topological invariant or Chern number. The Chern number corresponds to the number of discrete charges that would be pumped across the length of the nanowire when the phase of a sliding gate potential relative to that of the sinusoidal curvature is varied adiabatically over a complete period. In addition, coupling to an external magnetization can be utilized as an experimental knob to modify the Chern number by displacing the energies of the curvature-induced bands relative to one another. The magnetization can be tuned to achieve large discrete jumps in the number of pump charges per phase period.
Prediction of electrical properties of FDSOI devices based on deep learning
Authors: Zhao Rong , Wang Shulong , Duan Xiaoling , Liu Chenyu , Ma Lan , Chen Shupeng , Liu Hongxia
Published: May 2022

Fully depleted Silicon on insulator technology (FDSOI) is proposed to solve the various non-ideal effects when the process size of integrated circuits is reduced to 45 nm. The research of traditional FDSOI devices is mostly based on simulation software, which requires a lot of calculation and takes a long time. In this paper, a deep learning (DL) based electrical characteristic prediction method for FDSOI devices is proposed. DL algorithm is used to train the simulation data and establish the relationship between the physical parameters and electrical characteristics of the device. The network structure used in the experiment has high prediction accuracy. The mean square error of electrical parameters and transfer characteristic curve is only 4.34 × 10–4 and 2.44 × 10–3 respectively. This method can quickly and accurately predict the electrical characteristics of FDSOI devices without microelectronic expertise. In addition, this method can be extended to study the effects of various physical variables on device performance, which provides a new research method for the field of microelectronics.
Deep learning for dose assessment in radiotherapy by the super-localization of vaporized nanodroplets in high frame rate ultrasound imaging
Authors: van der Heyden Brent , Heymans Sophie V , Carlier Bram , Collado-Lara Gonzalo , Sterpin Edmond , D’hooge Jan
Published: May 2022

Objective. External beam radiotherapy is aimed to precisely deliver a high radiation dose to malignancies, while optimally sparing surrounding healthy tissues. With the advent of increasingly complex treatment plans, the delivery should preferably be verified by quality assurance methods. Recently, online ultrasound imaging of vaporized radiosensitive nanodroplets was proposed as a promising tool for in vivo dosimetry in radiotherapy. Previously, the detection of sparse vaporization events was achieved by applying differential ultrasound (US) imaging followed by intensity thresholding using subjective parameter tuning, which is sensitive to image artifacts. Approach. A generalized deep learning solution (i.e. BubbleNet) is proposed to localize vaporized nanodroplets on differential US frames, while overcoming the aforementioned limitation. A 5-fold cross-validation was performed on a diversely composed 5747-frame training/validation dataset by manual segmentation. BubbleNet was then applied on a test dataset of 1536 differential US frames to evaluate dosimetric features. The intra-observer variability was determined by scoring the Dice similarity coefficient (DSC) on 150 frames segmented twice. Additionally, the BubbleNet generalization capability was tested on an external test dataset of 432 frames acquired by a phased array transducer at a much lower ultrasound frequency and reconstructed with unconventional pixel dimensions with respect to the training dataset. Main results. The median DSC in the 5-fold cross validation was equal to ∼0.88, which was in line with the intra-observer variability (=0.86). Next, BubbleNet was employed to detect vaporizations in differential US frames obtained during the irradiation of phantoms with a 154 MeV proton beam or a 6 MV photon beam. BubbleNet improved the bubble-count statistics by ∼30% compared to the earlier established intensity-weighted thresholding. The proton range was verified with a −0.8 mm accuracy. Significance. BubbleNet is a flexible tool to localize individual vaporized nanodroplets on experimentally acquired US images, which improves the sensitivity compared to former thresholding-weighted methods.
Effect of temporal resolution on the detection of cardiac arrhythmias using HRV features and machine learning
Authors: Ben Itzhak Sagi , Ricon Shir Sharony , Biton Shany , Behar Joachim A , Sobel Jonathan A
Published: May 2022

Objective. Arrhythmia is an abnormal cardiac rhythm that affects the pattern and rate of the heartbeat. Wearable devices with the functionality to measure and store heart rate (HR) data are growing in popularity and enable diagnosing and monitoring arrhythmia on a large scale. The typical sampling resolution of HR data available from non-medical grade wearable devices varies from seconds to several minutes depending on the device and its settings. However, the impact of sampling resolution on the performance and quality of arrhythmia detection has not yet been quantified. Approach. In this study, we investigated the detection and classification of three arrhythmias, namely atrial fibrillation, bradycardia, tachycardia, from down-sampled HR data with various temporal resolution (5-, 15-, 30- and 60 s averages) in 1 h segments extracted from an annotated Holter ECG database acquired at the University of Virginia Heart Station. For the classification task, a total of 15 common heart rate variability (HRV) features were engineered based on the HR time series of each patient. Three different types of machine learning classifiers were evaluated, namely logistic regression, support vector machine and random forest. Main results. A decrease in temporal resolution drastically impacted the detection of atrial fibrillation but did not substantially affect the detection of bradycardia and tachycardia. A HR resolution up to 15 s average demonstrated reasonable performance with a sensitivity of 0.92 and a specificity of 0.86 for a multiclass random forest classifier. Significance. HRV features extracted from low resolution long HR recordings have the potential to increase the early detection of arrhythmias in undiagnosed individuals.
Mathematical modelling of haemorrhagic transformation within a multiscale microvasculature network
Authors: Wang Jiayu , Van Kranendonk Katinka R , El-Bouri Wahbi K , Majoie Charles B L M , Payne Stephen J
Published: May 2022

Objective. Haemorrhagic transformation (HT) is one of the most common complications after ischaemic stroke, caused by damage to the blood–brain barrier (BBB) that could be the result of stroke progression or a complication of stroke treatment with reperfusion therapy. The aim of this study is to develop further a previous simple HT mathematical model into an enlarged multiscale microvasculature model in order to investigate the effects of HT on the surrounding tissue and vasculature. In addition, this study investigates the relationship between tissue displacement and vascular geometry. Approach. By modelling tissue displacement, capillary compression, hydraulic conductivity in tissue and vascular permeability, we establish a mathematical model to describe the change of intracranial pressure (ICP) surrounding the damaged vascular bed after HT onset, applied to a 3D multiscale microvasculature. The use of a voxel-scale model then enables us to compare our HT simulation with available clinical imaging data for perfusion and cerebral blood volume (

C
B
V

) in the multiscale microvasculature network. Main results. We showed that the haematoma diameter and the maximum tissue displacement are approximately proportional to the diameter of the breakdown vessel. Based on the voxel-scale model, we found that perfusion reduces by approximately

13
–
17
%

and

C
B
V

reduces by around

20
–
25
%

after HT onset due to the effect of capillary compression caused by increased interstitial pressure. The results are in good agreement with the limited experimental data. Significance. This model, by enabling us to bridge the gap between the microvascular scale and clinically measurable parameters, providing a foundation for more detailed validation and understanding of HT in patients.
Mechanical properties of carbon nanotube reinforced polyurethane matrix using computational method: a molecular dynamics study
Authors: Pebdani Mohammadreza Heidari , Sabetvand Roozbeh
Published: May 2022

The reinforcing nanostructures can be made up of nanoparticles, nanosheets or nanofibres such as carbon nanotubes (CNTs) and graphene nanosheets. To investigate the reinforce mechanism, the changes in mechanical behavior of CNT reinforced Polyurethane (PU) matrix with various chirality was studied using molecular dynamics (MD) method in current work. We used the DREIDING and Tersoff force-fields for simulation of the PU and CNT samples, respectively. To report the mechanical properties of pristine PU matrix and reinforced PU/CNT structure, some physical parameters such as interaction energy between polymer chains and nanotube atoms, ultimate strength, and Young’s modulus are calculated. MD outputs indicated inserting CNT with zigzag edge into pristine matrix enlarged the Young’s modulus by 17.10% and the ultimate strength by 25.69%. These results indicated the promising effect of CNT-based nanostructures on the mechanical properties of PU matrix.
Superposition solutions to a (3+1)-dimensional variable-coefficient Sharma-Tasso-Olver-Like equation
Authors: Fan Lulu , Bao Taogetusang
Published: May 2022

In this paper, the superposition solutions of (3+1)-dimensional variable-coefficient Sharma-Tasso-Olver-Like(vcSTOL) equation are studied. The equation can illustrate various difficult sciences areas. Due to the wide application, it is very important to find the exact solutions of it. By introducing transformation, the equation is transformed into bilinear form. We use variable separation method and trial function method to obtain the superposition solutions of the equation containing different functions and forms The images are drawn with the help of symbolic computing system Mathematica, and the properties of the solutions are analyzed. The analysis shows that different functions will affect the overall shape of waves, including the interaction between waves, the size, the direction and the number of waves, which can get more new phenomena. To our knowledge, those types of superposition solutions of (3+1)-dimensional vcSTOL equation mentioned in our work by variable separation method have not been reported before. Furthermore, we add the square terms to the expansion function, so that the obtained solutions have the characteristics of Lump solution, which has not been done in the previous literatures.
Gravitational wave imprints of left-right symmetric model with minimal Higgs sector
Authors: Gráf Lukáš , Jana Sudip , Kaladharan Ajay , Saad Shaikh
Published: May 2022

We study the gravitational wave imprints of left-right symmetric model equipped with universal seesaw mechanism allowing for the natural generation of hierarchical masses of the Standard Model fermions. The scalar sector of this model is the minimal one, consisting of only two Higgs doublets. Following the construction of the full thermal potential for this model, we perform a scan of the entire parameter space and identify the region in which the cosmic phase transition associated with the left-right symmetry breaking gives gravitational wave signals detectable by a variety of planned space-based interferometers. Then we also discuss the relevant collider implications of this beyond the Standard Model scenario.
Koopman analysis of nonlinear systems with a neural network representation
Authors: Li Chufan , Lan Yueheng
Published: May 2022

The observation and study of nonlinear dynamical systems has been gaining popularity over years in different fields. The intrinsic complexity of their dynamics defies many existing tools based on individual orbits, while the Koopman operator governs evolution of functions defined in phase space and is thus focused on ensembles of orbits, which provides an alternative approach to investigate global features of system dynamics prescribed by spectral properties of the operator. However, it is difficult to identify and represent the most relevant eigenfunctions in practice. Here, combined with the Koopman analysis, a neural network is designed to achieve the reconstruction and evolution of complex dynamical systems. By invoking the error minimization, a fundamental set of Koopman eigenfunctions are derived, which may reproduce the input dynamics through a nonlinear transformation provided by the neural network. The corresponding eigenvalues are also directly extracted by the specific evolutionary structure built in.
Simpler optimized stellarators using permanent magnets
Authors: Qian T. , Zarnstorff M. , Bishop D. , Chamblis A. , Dominguez A. , Pagano C. , Patch D. , Zhu C.
Published: May 2022

A first-of-a-kind optimized stellarator for confining plasma has been designed and is being constructed with planar circular coils and permanent magnets composed of identical elements. The equilibrium is optimized to be quasi-axisymmetric for good particle confinement. The combination of permanent magnets and planar coils is significantly simpler to construct than fabricating three-dimensionally shaped coils, yet they are able to produce lower helical magnetic ripple than existing devices by two orders of magnitude in

ϵ

eff

3
/
2

, a characteristic neoclassical transport metric.
Recent regional warming across the Siberian lowlands: a comparison between permafrost and non-permafrost areas
Authors: Wang Ping , Huang Qiwei , Liu Shiqi , Cai Hongyan , Yu Jingjie , Wang Tianye , Chen Xiaolong , Pozdniakov Sergey P
Published: May 2022

The northern mid-high latitudes experience climate warming much faster than the global average. However, the difference in the temperature change rates between permafrost and non-permafrost zones remains unclear. In this study, we investigated the temporal changes in temperature means and extremes across the Siberian lowlands (<500 m) over the past six decades (1960–2019) using in situ observations and reanalysis data. The results show that permafrost zones (0.39 °C/decade) have warmed faster than non-permafrost zones (0.31 °C/decade). The minimum values of the daily maximum (TXn) and minimum (TNn) temperatures changed faster than their maximum values (TXx, TNx), suggesting that low minimum temperatures increase faster, as evidenced by the considerably higher warming rate in the cool season (October–April, 0.43 ± 0.10 °C/decade, n= 126) than that in the warm season (May–September, 0.25 ± 0.08 °C/decade, n= 119). The change rates of TXx and TNx in permafrost areas were 2–3 times greater than those in non-permafrost areas; however, over the last ten years, TXx and TNx in non-permafrost areas showed decreasing trends. Moreover, faster-warming permafrost regions do not exhibit a faster increase in surface net solar radiation than slower-warming non-permafrost regions. While our findings suggest that carbon emissions from thawing soils are likely a potential driver of rapid warming in permafrost-dominated regions, the potential feedback between ground thawing and climate warming in permafrost regions remains uncertain.
Assessing the quality of pedestrian paths related to street vendor activities at Johar Market, Semarang
Authors: Wungo G L , Mussadun  , Nathasya A , Manurung M A
Published: May 2022

This study examines pedestrian and street vendor activity in the vicinity of Johar Market, one of Semarang City’s busiest markets. Observations were made to get a complete picture of this study based on four targets: user characteristics, user movement patterns, physical environment characteristics around pedestrian paths, and the availability of street furniture. Data were obtained based on the results of seven days of observations, namely, over a thousand pedestrians and street vendor activities that occurred along the pedestrian path. Spatial analysis techniques with GIS are used to analyze the data from the observations. In addition, the pedestrian path’s quality is calculated using the PEQI (Pedestrian Environmental Quality Index) standard. The results of the analysis show that the quality of the pedestrian path around Johar Market is still relatively low, with a value of 19.84, placing it in category 4, indicating that the pedestrian path is insufficient because it does not meet the standard. The pedestrian path design category and the availability of street furniture received the lowest ratings. The results of this study can be used as reference material in designing pedestrian paths that meet the needs and meet service standards.
Development strategies for public space post-pandemic: A case study of Saigon-Ho Chi Minh City in the global context
Authors: Tran D T T , White M , Vo T T
Published: May 2022

The COVID-19 pandemic imposes huge challenges on urban development with its impacts on reshaping cities. Saigon-Ho Chi Minh City (HCMC), Vietnam is a typical mega-city with high population density coping with urban infrastructural issues. As social distancing and restrictions on the use of public space have been the key measures to deal with the pandemic, the communal areas in HCMC have been affected from both social and urban design aspects. The paper aims to explore the impacts during and after the COVID-19 epidemic on the public space in HCMC with the case study of four apartment residences in four different districts. It is carried on with 400 surveys and in-depth interviews with the apartment managers. Then, the case of public space in HCMC will be discussed to have a specific look into the issues in the global context. The article argues that despite the consequences of the pandemic to public areas, citizens’ need for these types of city elements persists. Finally, it provides suggestions for reshaping post-pandemic public spaces in both societies’ perception and urban planning strategy.
The Effectiveness of Plantaricin IIA-1A5 Powder Application to Extend the Storage of Fresh Cow’s Milk
Authors: Soenarno M S , Sumantri C , Arief I I , Taufik E , Nuraida L
Published: May 2022

Bacteriocins are peptides that have antimicrobial activity that are non-toxic, non-allergenic, heat-resistant and have broad bactericidal activity. Bacteriocin that has been declared safe by the FDA (Food and Drug Administration) and has been widely used in the food industry is nisin, which is mainly used in fruit products, dairy and meat processing industries. Bacteriocin from L. plantarum IIA-1A5 called plantarcin IIA-1A5, using whey growth media enriched with skim milk, has effectiveness as an antimicrobial against pathogenic bacteria E. coli and S. aureus. In this study, the application of plantaricin IIA-1A5 was conducted for fresh cow’s milk products from dairy cows on smallholder farms. The purpose of this study was to evaluate the effectiveness of the application of plantarcin IIA-1A5 powder using a certain dose to extend the storage period of fresh cow’s milk. Plantaricin IIA-1A5 powder was prepared with M1 concentration level of 5.58 g mL-1 and M2 concentration 11.17 g mL-1, then stored at frozen temperature. Nisin as a positive control was prepared at 11.17 g mL-1. Fresh milk that has been given treatment is then stored at room temperature for up to 6 hours and observed every 2 hours, namely at 0, 2, 4, and 6 hours of room temperature storage. The result showed that physicochemical quality of fresh milk did not change during treatments. Plantarisin IIA-1A5 was able to suppress the growth of total microbes at room temperature for two hours. The dose of plantaricin IIA-1A5 is effective for use in smallholder dairy farms or using non-cooled dairy machines at concentration of 11.17 g mL-1.
Correction of a relativistic impulse approximation expression used to obtain Compton profiles from photon scattering doubly differential cross sections
Authors: LaJohn Larry
Published: May 2022

A Compton profile (CP) can provide useful information about the electron populations and distributions in atoms, molecules, and ions to assess many physical properties of matter. However, a CP cannot be measured directly, but must be obtained from scattering data. The CPs discussed in this study are derived from photon-atom doubly differential cross sections (DDCS) via the following expression which is derived from an impulse approximation (IA) theory given by DDCS = KJ, where K represents a kinematic factor and J represents the CP. A relativistic version of this expression (i.e., RKJ)—an approximation of the full relativistic IA expression—is used for relativistic regimes; however, it does not yield accurate results for the inner and middle shells of moderate to heavy atoms. In this study, expressions from nonrelativistic (NR) hydrogen-like wavefunctions with a relativistic QED kinematic factor K

rel
and relativistic electron energy were derived to correct the RKJ expression for the K, L, M, and N atomic subshells. This derivation made it possible for relativistic contributions and screening effects to largely cancel, for any regime of energy angle and Z. Thus, the RKJ error which can be greater than 30% is reduced to within few percent over 99% of the electron momentum distribution range of any subshell CP when compared to published tabulated theoretical values. Two simple versions of the relativistic QED kinematic component of the corrected RKJ expressions were obtained and tested: one valid at high photon energies, and the other at small scattering angles. RKJ corrections were applied to the extraction of CP from the full spectrum K-N shell DDCS, which resulted in much improved accuracy for the K-shell. Good agreement was observed with tabulated beyond K-shell CPs around the tail regions, but systematic differences were found to occur at the maxima. The details of this phenomenon are illustrated and discussed in this article.
Variations in lead isotopes in Antarctic snow from northern Victoria Land during 2012–2015
Authors: Han Changhee , Kim Songyi , Lee Ah-Hyung , Han Yeongcheol , Lee Seungmi , Chang Chaewon , Hong Sungmin , Jung Hyejin , Hong Sang-Bum , Lee Jeonghoon , Hur Soon Do
Published: May 2022

To evaluate recent changes in anthropogenic Pb pollution and its sources and origins in Antarctica, Pb and Ba concentrations and Pb isotopic compositions were determined in a continuous series of 40 snow samples from a 2-m deep snow pit, covering 4 full years from 2011/12 summer to 2015/16 summer, at the Hercules Névé plateau in Victoria Land, Antarctica. The results show that more than 90% of the atmospheric Pb deposited in Victoria Land was of noncrustal origin. This result implies the persistence of a significant human impact on the atmospheric cycle of Pb in the most remote places on Earth, despite a substantial reduction in anthropogenic Pb emissions in the Southern Hemisphere during recent years. The Pb isotopic fingerprints indicate that South America, particularly Brazil and Chile, has become a major source of anthropogenic Pb reaching Victoria Land. Our data highlight the need for both national and international measures to further reduce Pb emissions.
Wind farm control technologies: from classical control to reinforcement learning
Authors: Dong Hongyang , Xie Jingjie , Zhao Xiaowei
Published: May 2022

Wind power plays a vital role in the global effort towards net zero. A recent figure shows that 93GW new wind capacity was installed worldwide in 2020, leading to a 53% year-on-year increase. The control system is the core of wind farm operations and has an essential influence on the farm’s power capture efficiency, economic profitability, and operation and maintenance cost. However, the inherent system complexities of wind farms and the aerodynamic interactions among wind turbines cause significant barriers to control system design. The wind industry has recognized that new technologies are needed to handle wind farm control tasks, especially for large-scale offshore wind farms. This paper provides a comprehensive review of the development and most recent advances in wind farm control technologies. It covers the introduction of fundamental aspects of wind farm control in terms of system modeling, main challenges and control objectives. Existing wind farm control methods for different purposes, including layout optimization, power generation maximization, fatigue load minimization and power reference tracking, are investigated. Moreover, a detailed discussion regarding the differences and similarities between model-based, model-free and data-driven wind farm approaches is presented. In addition, we highlight state-of-the-art wind farm control technologies based on reinforcement learning—a booming machine learning technique that has drawn worldwide attention. Future challenges and research avenues in wind farm control are also analyzed.
Robust and high-sensitivity thermal probing at the nanoscale based on resonance Raman ratio (R3)
Authors: Zobeiri Hamidreza , Hunter Nicholas , Xu Shen , Xie Yangsu , Wang Xinwei
Published: May 2022

Raman spectroscopy-based temperature sensing usually tracks the change of Raman wavenumber, linewidth and intensity, and has found very broad applications in characterizing the energy and charge transport in nanomaterials over the last decade. The temperature coefficients of these Raman properties are highly material-dependent, and are subjected to local optical scattering influence. As a result, Raman-based temperature sensing usually suffers quite large uncertainties and has low sensitivity. Here, a novel method based on dual resonance Raman phenomenon is developed to precisely measure the absolute temperature rise of nanomaterial (nm WS2 film in this work) from 170 to 470 K. A 532 nm laser (2.33 eV photon energy) is used to conduct the Raman experiment. Its photon energy is very close to the excitonic transition energy of WS2 at temperatures close to room temperature. A parameter, termed resonance Raman ratio (R3)

Ω
=

I

A

1g

/

I

E

2g

is introduced to combine the temperature effects on resonance Raman scattering for the A1g and E2g modes. Ω has a change of more than two orders of magnitude from 177 to 477 K, and such change is independent of film thickness and local optical scattering. It is shown that when Ω is varied by 1%, the temperature probing sensitivity is 0.42 K and 1.16 K at low and high temperatures, respectively. Based on Ω, the in-plane thermal conductivity (k) of a ∼25 nm-thick suspended WS2 film is measured using our energy transport state-resolved Raman (ET-Raman). k is found decreasing from 50.0 to 20.0 Wm−1 K−1 when temperature increases from 170 to 470 K. This agrees with previous experimental and theoretical results and the measurement data using our FET-Raman. The R3 technique provides a very robust and high-sensitivity method for temperature probing of nanomaterials and will have broad applications in nanoscale thermal transport characterization, non-destructive evaluation, and manufacturing monitoring.
Development and Implementation of a Standard Format for Clinical Laboratory Test Results
Authors: Hauser Ronald George , Quine Douglas B , Iscoe Mark , Arvisais-Anhalt Simone
Published: May 2022

Objectives

Surprisingly, laboratory results, the principal output of clinical laboratories, are not standardized. Thus, laboratories frequently report results with identical meaning in different formats. For example, laboratories report a positive pregnancy test as “+,” “P,” or “Positive.” To assess the feasibility of a widespread implementation of a result standard, we (1) developed a standard result format for common laboratory tests and (2) implemented a feedback system for clinical laboratories to view their unstandardized results.

Methods

In the largest integrated health care system in America, 130 facilities had the opportunity to collaboratively develop the standard. For 15 weeks, clinical laboratories received a weekly report of their unstandardized results. At the study’s conclusion, laboratories were compared with themselves and their peers by metrics that reflected their unstandardized results.

Results

We rereviewed 156 million test results and observed a 51% decline in the rate of unstandardized results. The number of facilities with fewer than 23 unstandardized results per 100,000 (Six Sigma σ > 5) increased by 58% (52 to 82 facilities; β = 1.79; P < .001).

Conclusions

This study demonstrated significant improvement in the standardization of clinical laboratory results in a relatively short time. The laboratory community should create and promulgate a standardized result format.