bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensing strain-induced symmetry breaking by reflectance anisotropy spectroscopy
Authors: Volpi M. , Beck S. , Hampel A. , Galinski H. , Sologubenko A. , Spolenak R.
Published: October 2021

Intentional breaking of the lattice symmetry in solids is a key concept to alter the properties of materials by modifying their electronic band structure. However, the correlation of strain-induced effects and breaking of the lattice symmetry is often indirect, resorting to vibrational spectroscopic techniques, such as Raman scattering. Here, we demonstrate that reflectance anisotropy spectroscopy (RAS), which directly depends on the complex dielectric function, enables the direct observation of electronic band structure modulation. Studying the strain-induced symmetry breaking in copper, we show how uniaxial strain lifts the degeneracy of states in the proximity of the both L and X symmetry points, thus altering the matrix element for interband optical transitions, directly observable in RAS. We corroborate our experimental results by analyzing the strain-induced changes in the electronic structure based on ab initio density functional theory calculations. The versatility to study breaking of the lattice symmetry by simple reflectance measurements opens up the possibility to gain a direct insight on the band structure of other strain-engineered materials, such as graphene and two-dimensional transition metal dichalcogenides.
Structure-induced broadband tunable resonances in soft material based dielectric metasurfaces
Authors: Khokhar Megha , Nair Rajesh V.
Published: October 2021

The dielectric metasurfaces using soft materials have generated opportunities in metamaterials by manipulating light interaction at a sub-wavelength scale. Here, we study the low-index dielectric metasurface consisting of a monolayer of dielectric micro-spheres in the visible region. The metasurface exhibits optical resonances, which appear as dips in the reflectivity spectra measured using the state-of-the-art micro-reflectivity facility. The origin of resonances is due to the diffraction of light on the corrugated surface, which appears as a grating mode or due to the light trapped within the micro-spheres termed as the leaky mode. The tunability of resonant modes is discussed as a function of the lattice constant and the effective refractive index of the metasurface. The experimental results are validated using the finite-difference time-domain simulations and theoretical calculations. The impact of the substrate refractive index is studied which shows higher refractive index contrast between the sample and the substrate, more light is confined within the metasurface. The proposed soft material-based metasurfaces can be used as a mask for making more complex photonic structures, generating structural coloration, and material base for rapid sensing.
Anomalous Nernst effect in Fe–Si alloy films
Authors: Hamada Yuki , Kurokawa Yuichiro , Yamauchi Tomoki , Hanamoto Hiroki , Yuasa Hiromi
Published: October 2021

We experimentally investigated the anomalous Nernst effect (ANE) in an Fe3Si film, whose ANE was predicted to be large, based on the topological property and the Berry curvature, and systematically compared it with other compositions of iron-silicide, viz., Fe2Si, FeSi, and FeSi2 films. Although both the ferromagnetic Fe3Si and Fe2Si films showed an ANE voltage, the highest ANE coefficient SANE = 1.0 μV K−1 was obtained for Fe3Si, which is larger than that for Fe. We also measured the Seebeck and anomalous Hall effects to estimate the transverse thermoelectric conductivity αyx, suggesting that the contribution of αyx was dominant in the Fe3Si ANE enhancement.
Impact wave dispersion characteristics in Bouligand-type structures
Authors: Yang Fan , Xie Weihua , Meng Songhe
Published: October 2021

A Bouligand structure is a special class of natural phononic crystals, which enables changes in configuration to achieve effective control of wave propagation. Here, we report an analytical modeling approach to study the impact energy filtering and the regulatory configuration mechanism in such structures. First, we demonstrate that by adjusting the helicity of structures and material properties of the Bouigand-type periodic structure, the size of bandgaps can be controlled and even implemented dispersion-free states. We then establish impact wave propagation models based on the propagator matrix method, which can be analytically evaluated for gradient-layered structures. Finally, we show that Bouligand-type materials with naturally occurring pitch gradient can effectively filter the impact energy generated by stomatopods. This is of interest for future design of vibration isolation devices, stealth aircraft skin, and offshore platform support and can provide important insight into structure–property relationships of the Bouligand-type structures.
Spin-lattice angular momentum transfer of localized and valence electrons in the demagnetization transient state of gadolinium
Authors: Decker Régis , Born Artur , Ruotsalainen Kari , Bauer Karl , Haverkamp Robert , Büchner Robby , Pietzsch Annette , Föhlisch Alexander
Published: October 2021

The electron–phonon scattering is one of the main microscopic mechanisms responsible for the spin-flip in the transient state of ultrafast demagnetization. Here, we present an experimental determination of the temperature-dependent electron–phonon scattering rate in Gd. Using a static x-ray emission spectroscopy method, where the reduction of the decay peak intensities when increasing the temperature is quantified, we measure independently the electron-phonon scattering rate for the 5d and the 4f electrons. We deduce the temperature dependence of scattering for the 5d electrons, while no effect on the phonon population is observed for the 4f electrons. Our results suggest that the ultrafast magnetization dynamics in Gd is triggered by the spin-flip in the 5d electrons. We also evidence the existence of a temperature threshold, above which spin-flip scattering of the 5d electrons takes place. We deduce that during the transient state of ultrafast demagnetization, the exchange energy between 5d electrons has to be overcome before the microscopic electron-phonon scattering process can occur.
Shape recovery of deformed biomolecular droplets: Dependence on condensate viscoelasticity
Authors: Zhou Huan-Xiang
Published: October 2021

A theoretical study on the shape dynamics of phase-separated biomolecular droplets is presented, highlighting the importance of condensate viscoelasticity. Previous studies on shape dynamics have modeled biomolecular condensates as purely viscous, but recent data have shown them to be viscoelastic. Here, we present an exact analytical solution for the shape recovery dynamics of deformed biomolecular droplets. The shape recovery of viscous droplets has an exponential time dependence, with the time constant given by the “viscocapillary” ratio, i.e., viscosity over interfacial tension. In contrast, the shape recovery dynamics of viscoelastic droplets is multi-exponential, with shear relaxation yielding additional time constants. During shape recovery, viscoelastic droplets exhibit shear thickening (increase in apparent viscosity) at fast shear relaxation rates but shear thinning (decrease in apparent viscosity) at slow shear relaxation rates. These results highlight the importance of viscoelasticity and expand our understanding of how material properties affect condensate dynamics in general, including aging.
Global well-posedness and decay for viscous water wave models
Authors: Granero-Belinchón Rafael , Scrobogna Stefano
Published: October 2021

The motion of the free surface of an incompressible fluid is a very active research area. Most of these works examine the case of an inviscid fluid. However, in several practical applications, there are instances where the viscous damping needs to be considered. In this paper, we derive and study a new asymptotic model for the motion of unidirectional viscous water waves. In particular, we establish the global well-posedness in Sobolev spaces. Furthermore, we also establish the global well-posedness and decay of a fourth order partial differential equation modeling bidirectional water waves with viscosity moving in deep water with or without surface tension effects.
An investigation of droplet mobility and the ultra-mild internal mechanical microenvironment in cylindrical microchannels
Authors: Li Mengqi , Liu Zhaomiao , Pang Yan , Wang Ju , Gao Shanshan , Zhao Siyu , Li Dezhi
Published: October 2021

The mechanical microenvironment inside droplets acts directly on encapsulated cells and reactive substances. We used microparticle image velocimetry to explore the flow characteristics inside droplets moving in cylindrical microchannels. Two kinds of flow behaviors were found inside droplets with increasing capillary number Ca. When Ca < 5.73 × 10−3, the oil phase cannot bypass droplets forward or backward because there is no gutter flow around the droplets, the droplets move in cylindrical microchannels in the form of rigid bodies, and the difference in velocity and gradients inside the droplets is very low. The fluids inside the droplets remain almost stationary with respect to the surrounding oil phase, and the droplets are driven only by compression. When Ca > 1.43 × 10−2, the droplets move faster than the oil phase, which creates a pair of counter-rotating eddies in the front of droplets, and the droplets are driven by both compression and shearing. The critical Ca range for the two flow behaviors is from 5.73 × 10−3 to 1.43 × 10−2 in this study. Comparisons are made between droplet behaviors in rectangular and cylindrical channels; in the latter, the shear and strain rate inside droplets are reduced by factors of 5.02 and 6.86, respectively, and acceleration and viscous dissipation are reduced by even greater factors of 42.53 and 41.56, respectively.
Experimental analysis of temperature effects in supercritical-assisted atomization
Authors: Shariatnia Shadi , Asadi Amir , Jarrahbashi Dorrin
Published: October 2021

Supercritical CO2 is proved as an excellent choice in supercritical-assisted atomization of nanoparticle suspensions for fabrication of micro/nano-powders. As the rheological properties of the supercritical fluids are strongly dependent on the temperature, the breakup mechanism of the CO2-liquid mixture upon injection is significantly affected by crossing the critical temperature of the binary mixture. In this study, we investigate the breakup of CO2-water mixture (CO2-A) at subcritical, critical, and supercritical states and compare it with the cases where N2 is utilized as the assisting fluid (N2-A) at the same injection conditions. High-speed imaging and laser diffraction systems are utilized to analyze the primary and secondary atomization of the injected CO2-water mixture (over 20 to 40 °C injection temperature range). In general, CO2-A showed smaller and more homogenous droplets compared to N2-A. Therefore, the use of CO2 as the atomization gas is superior to N2. The underlying mechanism in primary breakup of CO2-A involves the emergence, expansion, and burst of CO2 bubbles and formation of ligaments that break up into droplets. The core of the jet in CO2-A system expands up to 50% due to emergence of gas bubbles, while the expansion ratio remains unchanged in the N2-A jet. The finest and most homogenous droplet sizes are achieved by operating near the critical point at 31.5 °C and 7.5 MPa. High solubility of CO2 in water and low interfacial tension of the CO2-water mixture are the main contributors.
Using lures for improving selectivity of bait intake by red foxes
Authors: Tobajas Jorge , Descalzo Esther , Mateo Rafael , Ferreras Pablo
Published: October 2021

Abstract Context The use of baits for reducing the populations of harmful animal species, eradicating invasive species, vaccination, contraception or producing conditioned aversion, is widespread worldwide. However, baiting programs are often not successful enough and affect non-target species, requiring new approaches for baiting methods. Aims The aim of the present study was to evaluate two attractants used in carnivore studies to improve bait intake probability by red foxes and minimise bait intake by non-target species. Methods Non-toxic baits were distributed across 1000 ha, with bait intake monitored by camera traps during 3-week trials. Baits were assigned to two treatments with lures (lynx urine and Fatty Acid Scent – FAS) and one control. Bait intake by red foxes and non-target species was analysed using Generalised Linear Mixed Model (GLMM) and Kaplan–Meier survival analyses. Key results Lynx urine significantly increased the bait intake by red foxes (58.8%) compared with control (5.7%) and FAS (16.7%) treatment. However, FAS did not significantly increase the bait intake by red foxes compared with control. Bait intake by non-target species differed significantly between treatments, with lower intake in lynx urine (23.5%) treatment than control (54.7%), but not regarding FAS (36.7%), and neither between FAS and control. The probability of bait persistence after the 3-week trial period differed significantly among treatments, being lower in lynx urine treatment (0.18) than FAS (0.50) and control (0.43). All baits taken by foxes with lynx urine treatment (58.8%) occurred within the first 10 days, whereas intake by non-target species (23.5%) stopped after Day 7. Conclusions The use of lynx urine lure increased the proportion of baits consumed by red fox and reduced bait intake by non-target species. Implications Lures can serve to optimise bait delivery methods for red foxes in their different applications, such as conditioned aversion studies, vaccination, live trapping or predator control, while minimising risks to non-target species and reducing the costs and application time.
The association of opening K–12 schools with the spread of COVID-19 in the United States: County-level panel data analysis
Authors: Chernozhukov Victor , Kasahara Hiroyuki , Schrimpf Paul
Published: October 2021

Significance

This paper examines whether the opening of K–12 schools may lead to the spread of COVID-19. Analyzing how an increase of COVID-19 cases is related to the timing of opening K–12 schools in the United States, we find that counties that opened K–12 schools with in-person learning experienced an increase in the growth rate of cases by 5 percentage points on average, controlling for a variety of policies, past infection rates, and other factors. This association of K–12 school visits with case growth is stronger when mask wearing is not mandated for staff at school. These findings support policies that promote masking and other precautionary measures at schools and giving vaccine priority to education workers.
A preliminary description of mood in Welsh
Authors: Fontaine Lise , Williams Lowri
Published: October 2021

In this paper we propose a functional account of the Welsh mood system, focussing on responsives in particular.
The discourse functions of responsives are interpreted through the concept of negotiation within the systemic functional
linguistic framework, which offers a rich model for accounting for both initiations and responses, including possible tracking and
challenging moves. By examining the interaction of mood together with specific features of Welsh, e.g. a dominant VSO clause
ordering, mood particles, Subject ellipsis and a complex system of negation, we are able to show that Welsh tends to highlight
interpersonal meanings in clause initial position. As the first functional description of Welsh, we also set out important
directions for future research, based on the findings presented in this paper.
Inner-shell photoionization of free and confined Mg in the region of the 2p thresholds
Authors: Padukka P , Zhou H-L , Gorczyca T W , Manson S T
Published: October 2021

Photoionization of the free and confined Mg (Mg@C60) have been calculated in the vicinity of the inner-shell 2p thresholds using R-matrix at the Breit–Pauli R-matrix level with a particular emphasis on the various resonance series leading up to the two lowest inner-shell thresholds and the changes resulting from the confinement. For free Mg, the calculated resonance positions agree well with NIST values, and a number of new resonances are identified. For confined Mg, the calculation was done for various depths of the confining potential well in order to follow the trajectories of the resonances as a function of well depth. The results for the well depth corresponding to Mg@C60 showed that most of the resonances moved to higher photon energy, as a result of the confinement, but a few moved to lower energies. This phenomenology was found to result from the fact that the 3p, 3d and 4s excitations are trapped by the confining potential well, while the higher excitations were not.
Dynamical particle ratio fluctuations in Au + Au interaction at E
lab
= 30 A GeV using transport models
Authors: Ghosh S , Pal I , Thakur J , Mukhopadhyay A , Mali P
Published: October 2021

We present a simulation study on the dynamical fluctuations of conserved charges in a baryon-rich environment that is expected to be created in high-energy nucleus–nucleus (AB) collisions. Microscopic transport models like the ultra-relativistic quantum molecular dynamics and a multi-phase transport model are used to generate Au + Au collision events at an incident beam energy of 30 A GeV in the laboratory system. We investigate the centrality and rapidity window size dependence of the event-by-event (e-by-e) fluctuations of the multiplicity ratios of particles belonging to different species. It is observed that e-by-e dynamical fluctuations in the K/π, K/p and π/p ratios diminish with increasing centrality. Our results in this regard indicate that an AB collision can not be viewed as a mere superposition of many incoherent nucleon–nucleon (NN) collisions. Similarly, due to diffusion process the dynamical fluctuations get diluted with increasing window size of rapidity. The simulation results in general could be interpreted in terms of conventional mechanisms of particle production like resonance decays. Our simulation based analysis provides a useful reference baseline to the compressed baryonic matter experiment to be held at the Facility for Antiproton and Ion Research (FAIR).
Berry curvature induced magnetotransport in 3D noncentrosymmetric metals
Authors: Pal Ojasvi , Dey Bashab , Ghosh Tarun Kanti
Published: October 2021

We study the magnetoelectric and magnetothermal transport properties of noncentrosymmetric metals using semiclassical Boltzmann transport formalism by incorporating the effects of Berry curvature (BC) and orbital magnetic moment (OMM). These effects impart quadratic-B dependence to the magnetoelectric and magnetothermal conductivities, leading to intriguing phenomena such as planar Hall effect, negative magnetoresistance (MR), planar Nernst effect and negative Seebeck effect. The transport coefficients associated with these effects show the usual oscillatory behavior with respect to the angle between the applied electric field and magnetic field. The bands of noncentrosymmetric metals are split by Rashba spin–orbit coupling except at a band touching point (BTP). For Fermi energy below (above) the BTP, giant (diminished) negative MR is observed. This difference in the nature of MR is related to the magnitudes of the velocities, BC and OMM on the respective Fermi surfaces, where the OMM plays the dominant role. The absolute MR and planar Hall conductivity show a decreasing (increasing) trend with Rashba coupling parameter for Fermi energy below (above) the BTP.
Atomic configurations and energies of Mg symmetric tilt grain boundaries: ab initio local analysis
Authors: Xu Zhuo , Tanaka Shingo , Kohyama Masanori
Published: October 2021

Mg alloys are highly expected for the wide application in the next-generation industry, while significant improvement of the plasticity of polycrystalline Mg alloys is crucial. For this purpose, it is essential to get insights into the atomic configurations, energetics, and mechanical responses of Mg grain boundaries (GBs). In this study, we investigated the overall features of atomic configurations and energies of

[

1

1

¯

00

]

and

[

1

2

¯

10

]

symmetric tilt GBs in hcp Mg by density-functional theory. We systematically constructed atomic models of coincidence-site lattice GBs by the arrangement of structural units in the full range of rotation angles. We observed that special GBs show clear cusps in both the GB-energy and excess-volume curves against the rotation angle. The reason of the stability/instability of each GB configuration was analyzed by ab initio local energy and local stress based on Bader partitioning. The features of local energies and stresses in Mg GBs are quite different from those in other materials with covalent or partial-covalent bonding nature. We observed substantial variations of local energies, local stresses and Bader charges of GB atoms, and charge inhomogeneity in a GB region, reflecting the structural disorder. Stable GBs are characterized by modest ranges of such variations and by moderate charge homogeneity. These results could be utilized in general to understand the interface stability and deformation mechanism of Mg and other simple metals.
Fractional elliptic systems with critical nonlinearities
Authors: Bhakta Mousomi , Chakraborty Souptik , Miyagaki Olimpio H , Pucci Patrizia
Published: October 2021

This paper deals with existence, uniqueness and multiplicity of positive solutions to the following nonlocal system of equations:

(

−
Δ

)

s

u
=

α

2

s

*

|
u

|

α
−
2

u
|
v

|

β

+
f

(

x

)

in

R

N

,

(

−
Δ

)

s

v
=

β

2

s

*

|
v

|

β
−
2

v
|
u

|

α

+
g

(

x

)

in

R

N

,

u
,

v
>
0

in

R

N

,

(

S

)

where 0 < s < 1, N > 2s, α, β > 1, α + β = 2N/(N − 2s), and f, g are nonnegative functionals in the dual space of

H

˙

s

(

R

N

)

, i.e.,

〈

(

H

˙

s

)

′

f

,
u

〉

H

˙

s

⩾
0

, whenever u is a nonnegative function in

H

˙

s

(

R

N

)

. When f = 0 = g, we show that the ground state solution of

(

S

)

is unique. On the other hand, when f and g are nontrivial nonnegative functionals with ker(f) = ker(g), then we establish the existence of at least two different positive solutions of

(

S

)

provided that

‖
f

‖

(

H

˙

s

)

′

and

‖
g

‖

(

H

˙

s

)

′

are small enough. Moreover, we also provide a global compactness result, which gives a complete description of the Palais–Smale sequences of the above system.
Thermal stability of quasi-isotropic strands with different cross-sections and with/without metal sheaths
Authors: Zhang Guangyi , Wang Yinshun , Liu Wei , Wang Jian , Wang Jiawen
Published: October 2021

This paper mainly focuses on the thermal stability performance, such as minimum quench energy (MQE) and normal zone propagation velocity (NZPV), of a quasi-isotropic strand (Q-IS) with three different configurations made from 2G high-temperature superconducting (HTS) tapes in the adiabatic approximation. Due to the anisotropic performance of thermal conductivity in 2G HTS tapes, the tensor form of the heat conduction equation was used instead of conventional isotropic forms. We first measured the MQE and NZPV of three strands in the adiabatic approximation. Subsequently, the experimental results were verified by finite element analysis and compared with the values of MQE and NZPV in a liquid nitrogen (LN2) bath. Finally, the effect of a metal sheath on the current distribution and generation of Joule heat during the quench process were analyzed through simulation. The results show that the arc-shaped aluminum filler brings slightly higher thermal stability of Q-IS while the copper sheath largely improves stability. Moreover, compared with the thermal stability of the strand fully exposed to the LN2 bath, for the strand in the adiabatic approximation, the MQE decreases a lot while the maximum of NZPV is increased by 2–3 times.
Measurement of (n,α) and (n,2n) reaction cross sections at a neutron energy of 14.92 ± 0.02 MeV for potassium and copper with uncertainty propagation *
Authors: Gandhi A. , Sharma Aman , Pachuau Rebecca , Singh Namrata , Danu L. S. , Suryanarayana S. V. , Nayak B. K. , Kumar A.
Published: October 2021

Experimentally measured neutron activation cross sections are presented for the

(n,α)

,

(n,α)

, and

(n,2n)

reactions with detailed uncertainty propagation. The neutron cross sections were measured at an incident energy of 14.92 ± 0.02 MeV, and the neutrons were based on the t(d,n)α fusion reaction. The

(n,α)

reaction was used as a reference reaction for the normalization of the neutron flux. The pre-calibrated lead-shielded HPGe detector was used to detect the residues' γ-ray spectra. The data from the measured cross sections are compared to the previously measured cross sections from the EXFOR database, theoretically calculated cross sections using the TALYS and EMPIRE codes, and evaluated nuclear data.
Improve P300-speller performance by online tuning stimulus onset asynchrony (SOA)
Authors: Gao Pin , Huang Yihao , He Feng , Qi Hongzhi
Published: October 2021

Objective. The P300-Speller is a classic brain–computer interface paradigm that has been subjected to numerous clinical trials. Some studies have reported that the performance of the P300-Speller is closely related to stimulus onset asynchrony (SOA), but very few studies have attempted to improve the performance of the P300-Speller by optimizing SOA. Approach. In this paper, we designed a P300-Speller system based on a variable SOA and dynamic stop strategy, which can automatically adjust SOA according to real-time operational performance. Main results. The online experiment results of 18 subjects showed that the event-related potential classifier and the dynamic stop algorithm established at 200 ms SOA can maintain the performance at a certain level among 50–300 ms SOA. The system can then reduce the SOA from an initial 200 ms to an average of about 98.5 ms while maintaining letter output accuracy. The average theoretical information transfer rate was significantly improved from 42.4 to 85 bit min−1 (the maximum was 232 bit min−1). Significance. These results demonstrate that the system established in this paper can automatically optimize the SOA settings, and this personalized SOA adjustment can effectively improve the performance of the P300-Speller.
Stellarator coil design using cubic splines for improved access on the outboard side
Authors: Lonigro Nicola , Zhu Caoxiang
Published: October 2021

In recent years many efforts have been undertaken to simplify coil designs for stellarators due to the difficulties in fabricating non-planar coils. The FOCUS code removes the need for a winding surface and represents the coils as arbitrary curves in 3D. In the following work, the implementation of a spline representation for the coils in FOCUS is described, along with the implementation of a new engineering constraint to design coils with a straighter outer section. The new capabilities of the code are shown as an example on HSX, NCSX, and a prototype quasi-axisymmetric reactor-sized stellarator. The flexibility granted by splines along with the new constraint will allow for stellarator coil designs with improved accessibility and simplified maintenance.
Towards fully-predictive transport modelling in ASDEX Upgrade H-modes
Authors: Tardini G. , Angioni C. , Kiefer C.K. , Luda T. , Bonanomi N. , Dunne M. , Fable E. , Ryter F. , the ASDEX Upgrade Team
Published: October 2021

The common way to predict energy confinement in future devices such as ITER is to use scaling laws, based on parameters regression of large cross-machine databases. However, this approach is limited: the regression variables are not purely engineering parameters, physics quantities such as the plasma density n
e are also input; power regressions fail to capture important physics such as regime transitions; profile effects such as T
i/T
e or reverse magnetic shear are not retained. As a consequence, the scatter is large, but even some dependences are known to be of limited validity, such as the n
e or P dependences of the IPB98(y, 2) scaling. Dimensionless physics, if validated, provides a reliable basis for predicting confinement in a future device. However, there are no experimental data to use as boundary condition, nor empirical knowledge based on that device. Also, the use of full gyro-kinetic codes with all relevant ingredients is computationally unfeasible for a full-radius modelling. Integrated modelling with the recently developed IMEP workflow allows to simulate from the separatrix to the plasma centre, without making use of any experimental input. Although physics-based models are used to predict core transport, core transport is shown to be predicted with less accuracy than the pedestal energy. Therefore, we validate the most established quasi-linear models TGLF and QuaLiKiZ in different regimes and experimental conditions, assessing their strengths and limits. The quasi-linear models are shown to predict transport accurately in a variety of experimental conditions, including dominant ion and electron heating, respectively. The well-known shortcoming near the pedestal top is solved, while a new collision operator in the QuaLiKiZ model improves the electron temperature simulation significantly. Also the Neural Network version of QuaLiKiZ, with very fast computation time, appears to be well applicable in ion heated H-modes.
Fast collective evasion in self-localized swarms of unmanned aerial vehicles
Authors: Novák Filip , Walter Viktor , Petráček Pavel , Báča Tomáš , Saska Martin
Published: October 2021

A novel approach for achieving fast evasion in self-localized swarms of unmanned aerial vehicles (UAVs) threatened by an intruding moving object is presented in this paper. Motivated by natural self-organizing systems, the presented approach of fast and collective evasion enables the UAV swarm to avoid dynamic objects (interferers) that are actively approaching the group. The main objective of the proposed technique is the fast and safe escape of the swarm from an interferer discovered in proximity. This method is inspired by the collective behavior of groups of certain animals, such as schools of fish or flocks of birds. These animals use the limited information of their sensing organs and decentralized control to achieve reliable and effective group motion. The system presented in this paper is intended to execute the safe coordination of UAV swarms with a large number of agents. Similar to natural swarms, this system propagates a fast shock of information about detected interferers throughout the group to achieve dynamic and collective evasion. The proposed system is fully decentralized using only onboard sensors to mutually localize swarm agents and interferers, similar to how animals accomplish this behavior. As a result, the communication structure between swarm agents is not overwhelmed by information about the state (position and velocity) of each individual and it is reliable to communication dropouts. The proposed system and theory were numerically evaluated and verified in real-world experiments.
Structural, dielectric, impedance, complex modulus, and optical study of Ni-doped Zn(1−x)NixO nanostructures at high temperatures
Authors: Ahmad Fiaz , Maqsood Asghari
Published: October 2021

This experiment addressed the effect of Nickel-doped on the dielectric, ac conductivity, and optical properties of pure and doped Zn (1−x) Nix O (x = 0, 3 and 6%) nanostructures. The un-doped and Ni-doped ZnO nanostructures were synthesized using co-precipitation. In this paper, the frequency-dependent dielectric and the electrical conductivity of un-doped and Ni-doped Zn (1−x) Nix O nanostructures were examined at various temperatures ranging from 320 K to 460 K using an LCR meter. For the morphological and optical investigation, the prepared samples were analyzed using field emission-scanning electron microscopy (FE-SEM), and UV visible Spectroscopy was used at room temperature. The dielectric constant (

ε
′

), dielectric loss (

ε

″

), tangent loss (tan δ), the real as well as the imaginary part of the impedance against the frequency ranging from 100 Hz to 2 × 106 Hz that declines with increases in frequency at different temperatures ranging from 320–460 K. However, the electrical conductivity (

σ

a
c

) increased with the increase in frequency was examined. The ac conductivity (

σ

a
c

) follows Jonscher,s power law that the electrical conductivity is enhanced with increasing doping concentration. The optical transmission area also improved due to an increase in Ni-doping concentration in ZnO. The optical bandgap of pure and Ni-doped ZnO nanostructures is in the range lies 3.30–3.12 eV found that to decrease with the increase in Ni doping concentrations.
Study on mechanism of carbonaceous gold ore during oxidation roasting by kinetics: phase transformation and structure evolution
Authors: Li Hui , Jin Jianping , Han Yuexin , Xiao Wei , Zhou Zhenya
Published: October 2021

The pretreatment and effective utilization of carbonaceous gold ore is of significant to refractory gold resources. In this work, the calcination kinetics was employed to investigate the relationship between phase transformation and structure evolution of carbonaceous gold ore during roasting process. Mechanism functions were determined and the fact that roasting process was controlled by chemical reaction in the initial 90 min and dominated by internal diffusion as time reached to 120 min was uncovered. In addition, the apparent activation energies for initial and latter roasting stage were 212.11 kJ·mol−1 and 163.73 kJ·mol−1, respectively. Combined with the analysis of phase transformation and structure evolution, the removal of carbonaceous matter and appearance of new tiny pores contributed to the change of calcination kinetics. Moreover, phase transformation and structure evolution were beneficial for elevating Au recovery during leaching experiment. These findings helped to understand the mechanism of carbonaceous minerals during roasting and provided new insight for the utilization of refractory gold resource.
Effect of perfluoropolyether and the micro nano structure of ZnO on anti icing performance of fluorinated organic superhydrophobicity coatings on wind turbine blade surface
Authors: Zeng Zijing , He Jianjun , Jie Jun , Zhou Chengwei , Chen Biao , Bao Jiangyong , Yang Kaijun , Luo Jin
Published: October 2021

The ice coating on the blade surface of wind turbine in winter seriously affects the operation safety and power generation efficiency of wind turbine, and anti icing and deicing is an urgent technical problem. In this paper, a super-hydrophobic anti-icing coating was prepared by fluorination modification, and the effect of the addition of perfluoropolyether (PFPE) and ZnO on the performance of the coating was studied. The research results show that the addition of PFPE reduces the surface energy of the coating from 18.12 mJ m−2 at 0% to 13.22 mJ m−2 at 15%. The surface free energy has a linear relationship with the binding force of icing. With the increase of the amount of PFPE, the contact angle of the coating increases, the sliding angle decreases, and the delayed icing performance improves. When the amount of PFPE reaches 15%, the contact angle reaches the highest value of 158°, and the sliding angle is 2°; adding PFPE coating, the freezing delay time can reach 107.1 s. The addition of PFPE can effectively reduce the icing strength, and the icing bonding force of the coating is reduced to 0.59 N at 15%. The addition of a amount of ZnO can greatly change the microstructure of the coating surface, thereby changing its superhydrophobicity. The fluorinated superhydrophobicity coating modified by the addition and removal of ZnO has obvious anti-icing performance. The 6 wt% sample has the best delayed icing energy.
Identification of Fe-Zn coating behaviors by a new reverse approach using artificial intelligence
Authors: Nasser Mohamed , Attyaoui Slimen , Tlili Brahim , Montagne Alex , Briki Jalel , Iost Alain
Published: October 2021

Nanoindentation is a technique commonly used to measure the mechanical properties of thin films even at depths less than 1 μm. In fact, the characterization is based on the study of the load/displacement curves resulting from the nanoindentation test. We aim to use the backtracking search optimization algorithm (BSA) to improve the extraction of P(h) curves performed by nanoindentation on galvannealed Fe-Zn coating in terms of precision and dispersion. Indeed, the originality of this study is not limited only to the P(h) curve extraction methods, but also to its application in modeling the reverse approach for the case of Fe-Zn coating deposited on a Dual-Phase DP600 steel substrate. Indeed, the BSA approach showed more precision (with respect to the determined mean value) and less dispersion (magnitude of error around the identified mean value) compared to the Least-squares approach. The average error with the BSA and LS methods is respectively 0.89% and 3.16% for the yield stress

σ

Y

and 3.17% and 7.93% for the strain hardening exponent (n). This reduced the error variability in the prediction of the constitutive law to 72% and 60% for (

σ

Y

) and n, respectively. Thus, we solved the problems of accessibility, uniqueness of the solution, precision (+10%) and dispersion (−85%) of the required prediction models for the Fe-Zn coating behavior.
Strain in heterogeneous quantum devices with atomic layer deposition
Authors: Kennedy Oscar W , O’Sullivan James , Zollitsch Christoph W , Thomas Christopher N , Withington Stafford , Morton John J L
Published: October 2021

We investigated the use of dielectric layers produced by atomic layer deposition (ALD) as an approach to strain mitigation in composite silicon/superconductor devices operating at cryogenic temperatures. We show that the addition of an ALD layer acts to reduce the strain of spins closest to silicon/superconductor interface where strain is highest. We show that appropriately biasing our devices at the hyperfine clock transition of bismuth donors in silicon, we can remove strain broadening and that the addition of ALD layers left T
2 (or temporal inhomogeneities) unchanged in these natural silicon devices.
Energy access investment, agricultural profitability, and rural development: time for an integrated approach
Authors: Falchetta Giacomo
Published: October 2021

In rural sub-Saharan Africa, the global poverty hotspot, smallholder farmers account for 80% of agricultural production, with 90% of cropland being exclusively rainfed. A key obstacle to rural development and poverty elimination is the lack of electricity access: less than one in three dwellers have electricity at home. The main barrier to rural electrification is the capital-intensiveness of energy supply infrastructure among sparse communities with low demand density and insecurity of payment. While public governments have largely been unable to channel the required resources, private players are often unwilling to pursue risky and unprofitable household electrification programs. In this context, this perspective argues that the paradigm of rural electrification should be centred around an integrated approach aiming at increasing agricultural productivity and profitability. These bear the necessary potential to enable local income generation and thus also provide an incentive for private energy investment, including in the residential sector. A framework for the integrated approach is proposed and the crucial synergetic role of data modelling and business and policy research to pursue this paradigm is discussed.
Geometry of Kleinian groups and its applications
Authors: Ohshika Ken’ichi
Published: October 2021

The notion of Kleinian groups was first introduced by Poincaré in the 19th century, and their study from a viewpoint of complex analysis was developed by Ahlfors, Bers, Kra, Maskit and Marden among others. After Thurston’s innovative work, topological study of Kleinian groups was started and flourished. In this survey article, we look back on Thurston’s influential work and his famous 10 open questions, and explain their significance and how they have been solved. In the latter half, we shall look at more recent development of the theory of Kleinian groups.
Diophantine approximation
Authors: Hirata-Kohno Noriko
Published: October 2021

This article gives an introductory survey of recent progress on Diophantine problems, especially consequences coming from Schmidt’s subspace theorem, Baker’s transcendence method and Padé approximation. We present fundamental properties around Diophantine approximation and how it yields results in number theory.
Neuron segmentation using 3D wavelet integrated encoder–decoder network
Authors: Li Qiufu , Shen Linlin
Published: October 2021

Motivation

3D neuron segmentation is a key step for the neuron digital reconstruction, which is essential for exploring brain circuits and understanding brain functions. However, the fine line-shaped nerve fibers of neuron could spread in a large region, which brings great computational cost to the neuron segmentation. Meanwhile, the strong noises and disconnected nerve fibers bring great challenges to the task.

Results

In this article, we propose a 3D wavelet and deep learning-based 3D neuron segmentation method. The neuronal image is first partitioned into neuronal cubes to simplify the segmentation task. Then, we design 3D WaveUNet, the first 3D wavelet integrated encoder–decoder network, to segment the nerve fibers in the cubes; the wavelets could assist the deep networks in suppressing data noises and connecting the broken fibers. We also produce a Neuronal Cube Dataset (NeuCuDa) using the biggest available annotated neuronal image dataset, BigNeuron, to train 3D WaveUNet. Finally, the nerve fibers segmented in cubes are assembled to generate the complete neuron, which is digitally reconstructed using an available automatic tracing algorithm. The experimental results show that our neuron segmentation method could completely extract the target neuron in noisy neuronal images. The integrated 3D wavelets can efficiently improve the performance of 3D neuron segmentation and reconstruction.

Availabilityand implementation

The data and codes for this work are available at https://github.com/LiQiufu/3D-WaveUNet.

Supplementary information

Supplementary data are available at Bioinformatics online.
68 Outcomes of Emergency Appendicectomy At Torbay Hospital During Peak SARS-COV-2 Pandemic
Authors: Babar M , Whitmore H , Goodrum S
Published: October 2021

Introduction

SARS-COV-2 has created unprecedented challenges for healthcare systems. As a result, new intercollegiate guidelines have been published in the UK to manage emergency surgeries commencing 25th March 2020. Devon has one of the lowest incidences of Covid-19 in UK. In this study, we report outcomes of emergency appendicectomy at Torbay Hospital during peak COVID-19 pandemic, from 25th March till 26th May 2020.

Method

This is a single centre retrospective review at Torbay Hospital, Devon. It includes all patients who underwent emergency appendicectomy. Primary outcomes were intra-operative findings, change of operation choice due to revised guidelines, and length of admission. The secondary outcome was 14 days post-operative mortality and morbidity.

Results

A total of 29 patients, median age 33.1, underwent emergency appendicectomy. 79.3% (n = 23) had a pre-operative SARS-COV-2 nasal swab test, all of which were negative. All appendicectomies were conducted in a non-COVID theatre. Level 3 PPE and precautions were used intra-operatively. The choice of operation was changed in 37.9% (n = 10), from laparoscopic to open as per COVID-19 guidelines. Most patients (86.2%) were discharged from hospital within 5 days of operation. None of the patients or surgeons contracted COVID-19 related infection in 14 days following the operation.

Conclusions

This study is a snapshot into safety of operative management of acute appendicitis in patients not suspected of COVID-19 infection during first wave of pandemic. However, it will be interesting to see long-term multi-centre comparative studies analysing the effect of surgical management of appendicitis during all three waves of pandemic.
91 Management and Outcomes of Appendicitis in The Pre-COVID-19, COVID-19 And Post-COVID-19 Periods
Authors: Abeywickrema M , Patel C , Ghumman A K , Krishan A , Puventhiranathan P , Mae Kelly G , Nijjar R
Published: October 2021

Aim

The COVID-19 pandemic resulted in an upheaval of national surgical guidance on appendicitis, which has previously favoured surgical over conservative approaches. We analysed how these guidelines altered management and outcomes of appendicitis.

Method

A retrospective cohort study at Heartlands Hospital, Birmingham of all appendicitis admissions around and during the first COVID-19 peak was conducted, with analysis of electronic patient records using the acute surgical worklist.

Results

48 admissions for appendicitis during the two-month period from 01/02/20 to 25/03/20 prior to the COVID-19 peak and 28 admissions in the two months during the peak itself from 30/03/20 to 24/05/20 were identified. Prior to the COVID-19 peak, a lower proportion of cases was managed conservatively (18.8%) compared to the latter (67.9%, p < 0.0001). This change also coincided with a switch from laparoscopic to open approaches in those managed surgically. We studied a further period post-COVID-19 peak from 01/06/20 to 26/07/20, where proportions of patients managed conservatively versus surgically did not significantly change following the COVID-19 peak, although surgical preference reverted from open to laparoscopic approaches. During the COVID-19 period, a reduced length of stay was seen in cases managed conservatively (1.65 days) compared to those managed surgically (4 days, p = 0.024). Differences in readmission rates were not statistically significant.

Conclusions

A reduction in numbers of appendicitis presentations as well as a switch to conservative approaches was seen during COVID-19. These findings furthermore support non-inferiority of conservative over open surgical approaches in most appendicitis cases at a time where laparoscopy was deemed unfeasible.
160 Informed Consent for Surgery at Resumption of Elective Activity After the First Wave of COVID-19
Authors: Darwish N , Iqbal M , Dhahri Adeel A , Jacob N , Jebamani J , Easthope A , Vijay V
Published: October 2021

Aim

The Royal College of Surgeons of England published guidance on consent during COVID-19. Through this study, we aimed to assess our local consent adherence to these guidelines on the resumption of elective activity after the first wave of COVID-19.

Method

This prospective review of consecutive elective surgical consent forms was conducted from 20 July 2020 to 16 August 2020 at the Princess Alexandra Hospital NHS Trust, England. The primary outcome was evidence of COVID-19 risk documentation on the consent forms.

Results

A total of 116 patients’ consent forms were reviewed. Most patients were American Society of Anaesthesiologists (ASA) grade 2 (n = 70; 60.34%). Only 25 consent forms (21.55%) had COVID -19 and its associated risks documented, with registrars being the most compliant (19/46; 41.3%) followed by consultants (6/51; 11.7%). With regards to the surgical sub-specialities, general surgery, orthopaedics and ENT had the highest compliance with the guidance.

Conclusions

As the elective activity resumes, peri-operative risks of COVID-19 should be weighted in during the informed consent process, as mentioned in the latest international guidelines on consent to avoid litigation and negligence claims.