bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-dimensional numerical analysis and experimental confirmation for investigating the ground-based lateral droplet ejection toward microgravity simulation
Authors: Zhao Lei , Qi Lehua , Luo Jun , Huang Jieguang , Hou Xianghui
Published: October 2022

Rapid in situ manufacturing is significant in space exploration. Droplet-based printing technology with micrometer accuracy has great potential in space due to the advantages of convenient transportation, customized metal material, and good environmental adaptability. It could achieve the ground microgravity simulation by a small Bond number (Bo < 1). The present work proposes a new method to evaluate the reliability of the ground microgravity simulation in the lateral metallic droplet-based ejection. The three-dimensional model is developed to numerically analyze the droplet ejection dynamic process coupled with the volume of fluid method and the k–ω shear stress transport model. The model accuracy and efficiency are improved by the local fine grid. In addition, the computation is validated by the cryogenic alloy droplet ejection experiments and theoretical analysis. The proposed theoretical analysis equation has good agreement with the SnPb alloy droplet ejection trajectory. Reynolds number (Re), Weber number (We), Froude number (Fr), Ohnesorge number (Oh), and breakup length (Lb) are used to analyze the gravity influences on the droplet ejection process of different materials, nozzle length–diameter ratios, and crucible fluid unfilled heights. The ejection direction has little effect on the aluminum droplet formation time and breakup length and the gravity effect increases with the length–diameter ratio and unfilled heights. In simulated results, the minimum We number of the aluminum droplet formation is 0.22 and the cryogenic alloy droplet formation is 0.19. The reliability of ground physical microgravity simulation is dependent on material selection, and aluminum is more suitable than the cryogenic and SnPb alloys.
High-resolution fiber imaging for pulsed power experiments
Authors: Fulford K. W. , Yager-Elorriaga D. A. , Patel S. , Montoya M. M. , Chandler K. , Gilmore M. A.
Published: October 2022

This work presents a novel approach for imaging the visible emissions from plasmas in pulsed power experiments using high-resolution plastic optical fibers. The diagnostic consists of a 2 mm diameter core commercial cable constructed of 13 000 individual acrylic fibers. The fibers are fused together to create a single high-resolution bundle. Different designs were investigated to cover a wide range of resolutions and fields of view (3–700 µm and 0.05–45 mm, respectively). The system was tested on the 1-MA Mykonos accelerator at Sandia National Laboratories and successfully imaged visible emission from a hybrid x-pinch target. Diagnostic development and preliminary results are presented.
Cavitation in cryogenic fluids: A critical research review
Authors: Wei Aibo , Yu Lianyan , Qiu Limin , Zhang Xiaobin
Published: October 2022

Cavitation occurs as the fluid pressure is lower than the vapor pressure at a local thermodynamic state and may result in huge damage to the hydraulic machinery. Cavitation in cryogenic liquids is widely present in contemporary science, and the characteristics of cryogenic cavitation are quite different from those of water due to thermal effects and strong variations in fluid properties. The present paper reviews recent progress made toward performing experimental measurements and developing modeling strategies to thoroughly investigate cryogenic cavitation. The thermodynamic properties of cryogenic fluids are first analyzed, and different scaling laws for thermal effects estimation are then introduced. As far as cryogenic cavitation experimental research is concerned, the progress made in the cavitation visualization and cavity dynamics and the synchronous measurements of the multi-physical field are mainly introduced. As for the study on numerical simulation of cryogenic cavitation, the commonly used cavitation models and turbulence models are, respectively, classified and presented, and the modifications and improvements of the cavitation model and turbulence model for thermal effect modeling of cryogenic cavitation are examined. Then, several advances of critical issues in cryogenic fluid cavitation research are reviewed, including the influences of thermal effects, unsteady shedding mechanisms, cavitation–vortex interactions, and cavitation-induced vibration/noise. This review offers a clear vision of the state-of-the-art from both experimental and numerical modeling viewpoints, highlights the critical study developments and identifies the research gaps in the literature, and gives an outlook for further research on cryogenic cavitation.
Magnetization reversal tuning in honeycomb ferrimagnet Ni4Nb2O9
Authors: Bolletta Juan P. , Fauth François , Martin Christine , Maignan Antoine
Published: October 2022

Ni4Nb2O9 displays magnetization reversal, a particular behavior in which magnetization opposes an applied magnetic field. Previous studies have shown that this is caused by the antiferromagnetic coupling of two different layers of ferromagnetic Ni cations. In this work, magnetization reversal is controlled by the substitution of Ni by non-magnetic Zn. Ni4−xZnxNb2O9 materials with x = 0.25, 0.50, and 0.75 maintain the orthorhombic Ni4Nb2O9-type structure but display counterintuitive changes in the magnetic properties including increases in low-temperature net magnetizations, remnant magnetizations, and compensation temperatures. Furthermore, the magnetization reversal is significantly enhanced for x = 0.50 while supressed for x = 0.75, underscoring the strong effects of Zn substitution.
A grating-chip atomic fountain
Authors: Lewis Ben , Elvin Rachel , Arnold Aidan S. , Riis Erling , Griffin Paul F.
Published: October 2022

Cold atom fountain clocks provide exceptional long term stability as they increase interrogation time at the expense of a larger size. We present a compact cold atom fountain using a grating magneto-optical trap to laser cool and launch the atoms in a simplified optical setup. The fountain is evaluated using coherent population trapping and demonstrates improved single-shot stability from the launch. Ramsey times up to 100 ms were measured with a corresponding fringe linewidth of 5 Hz. This technique could improve both short- and long-term stabilities of cold atom clocks while remaining compact for portable applications.
Excitation of long electrostatic solitary waves in ion beam neutralization process
Authors: Nuwal Nakul , Kaganovich Igor D. , Levin Deborah A.
Published: October 2022

Unusually long electrostatic solitary waves (ESWs) are discovered in a particle-in-cell simulation study of the process of ion beam neutralization by electron emission from a filament. These ESWs are long because the density perturbation responses to the potential wells created by the ESWs are very small. The density perturbation is small because the trapped (positive) and untrapped (negative) electron density perturbations nearly compensate each other because of a non-Maxwellian electron velocity distribution in the beam.
Electrical characteristics of normally off hydrogen-terminated diamond field effect transistors with lanthanum oxide gate dielectric
Authors: Su Jianing , Chen Genqiang , Wang Wei , Shi Han , He Shi , Lv Xiaoyong , Wang Yanfeng , Zhang Minghui , Wang Ruozheng , Wang Hong-Xing
Published: October 2022

A normally off hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor field effect transistor (MOSFET) is realized by using lanthanum oxide (La2O3) gate dielectric. The threshold voltage is demonstrated to be −0.797 V, indicating that the La2O3-gated H-diamond MOSFET has normally off characteristics. The normally off mode could be greatly ascribed to the low work function of La2O3. Based on the capacitance–voltage (C–V) curves, the dielectric constant of La2O3 is calculated to be as high as 25.6. Moreover, the small hysteresis voltage extracted from the C–V curves exhibits low trapped charge density in the La2O3 layer. The maximum drain–source current, maximum transconductance, subthreshold swing, effective mobility, current on/off ratio, and sheet hole density of La2O3-gated MOSFET with a gate length of 2 μm are calculated to be −13.55 mA/mm, 4.37 mS/mm, 161 mV/dec, 202.2 cm2/V·s, 108, and 6.53 × 1012 cm−2, respectively. This work will significantly promote the development of normally off H-diamond MOSFET devices.
Quantum dynamics using path integral coarse-graining
Authors: Musil Félix , Zaporozhets Iryna , Noé Frank , Clementi Cecilia , Kapil Venkat
Published: October 2022

The vibrational spectra of condensed and gas-phase systems are influenced by thequantum-mechanical behavior of light nuclei. Full-dimensional simulations of approximate quantum dynamics are possible thanks to the imaginary time path-integral (PI) formulation of quantum statistical mechanics, albeit at a high computational cost which increases sharply with decreasing temperature. By leveraging advances in machine-learned coarse-graining, we develop a PI method with the reduced computational cost of a classical simulation. We also propose a simple temperature elevation scheme to significantly attenuate the artifacts of standard PI approaches as well as eliminate the unfavorable temperature scaling of the computational cost. We illustrate the approach, by calculating vibrational spectra using standard models of water molecules and bulk water, demonstrating significant computational savings and dramatically improved accuracy compared to more expensive reference approaches. Our simple, efficient, and accurate method has prospects for routine calculations of vibrational spectra for a wide range of molecular systems - with an explicit treatment of the quantum nature of nuclei.
Effects of thermal expansion on moderately intense turbulence in premixed flames
Authors: Sabelnikov Vladimir A. , Lipatnikov Andrei N. , Nikitin Nikolay V. , Hernández-Pérez Francisco E. , Im Hong G.
Published: October 2022

This study aims at analytically and numerically exploring the influence of combustion-induced thermal expansion on turbulence in premixed flames. In the theoretical part, contributions of solenoidal and potential velocity fluctuations to the unclosed component of the advection term in the Reynolds-averaged Navier–Stokes equations are compared, and a new criterion for assessing the importance of the thermal expansion effects is introduced. The criterion highlights a ratio of the dilatation in the laminar flame to the large-scale gradient of root mean square (rms) velocity in the turbulent flame brush. To support the theoretical study, direct numerical simulation (DNS) data obtained earlier from two complex-chemistry, lean H2–air flames are analyzed. In line with the new criterion, even at sufficiently high Karlovitz numbers, the results show significant influence of combustion-induced potential velocity fluctuations on the second moments of the turbulent velocity upstream of and within the flame brush. In particular, the DNS data demonstrate that (i) potential and solenoidal rms velocities are comparable in the unburnt gas close to the leading edge of the flame brush and (ii) potential and solenoidal rms velocities conditioned to unburnt gas are comparable within the entire flame brush. Moreover, combustion-induced thermal expansion affects not only the potential velocity but even the solenoidal one. The latter effects manifest themselves in a negative correlation between solenoidal velocity fluctuations and dilatation or in the counter-gradient behavior of the solenoidal scalar flux. Finally, a turbulence-in-premixed-flame diagram is sketched to discuss the influence of combustion-induced thermal expansion on various ranges of turbulence spectrum.
Expansion of multicenter Coulomb integrals in terms of two-center integrals
Authors: Kovačević Goran
Published: October 2022

Three- and four-center Coulomb integrals in the solid spherical harmonic Gaussian basis are solved by expansion in terms of two-center integrals. The two-electron Gaussian product rule, coupled with the addition theorem for solid spherical harmonics, reduces four-center Coulomb integrals into a linear combination of two-center Coulomb integrals and one-center overlap integrals. With this approach, three- and four-center Coulomb integrals can be reduced to the same form of two-center integrals. Resulting two-center Coulomb integrals can be further simplified into a simpler form, which can be related to the Boys function. Multi-center Coulomb integrals are solved hierarchically: simple two-center Coulomb integrals are used for calculation of more complicated two-center Coulomb integrals, which are used in the calculation of multicenter integrals.
From adverb to intensifier
Authors: Pastuch Magdalena , Mitrenga Barbara , Wąsińska Kinga
Published: October 2022

This paper aims is to analyse the status of selected Polish words: okrutnie (‘cruelly’), strasznie (‘terribly’) and szalenie (‘madly’). These units are traditionally considered to be adverbs, and their formal structure and original meaning indicate derivation from proper adjectives. We presume that adverbs might develop into intensifiers, which are semantically close to bardzo (‘very’). By analysing the linguistic material extracted from chronologically differentiated corpora of Polish (korba, kf19 and nkjp), we want to show how this linguistic process has been evolving over the centuries. Our research examines quantitative and qualitative collocational data of okrutnie, strasznie and szalenie with their categorical value and semantic evaluation (positive, neutral and negative). Our research reveals that the changing of words’ meaning, and their syntactic function, switched from the object language to the metalanguage level, is a feature associated with grammaticalization. We used a statistical chi-square test to verify the probability of word co-occurrence.
Employing retrospective process tracing in an international exploratory study
Authors: Gumul Ewa , Herring Rachel E.
Published: October 2022

This paper reports on a RPT study which employed an adapted version of the three-stage method used by Herring (2018). The same stimulus and method were employed with two distinct populations
(experienced medical interpreters in the USA and student interpreters in Poland), with the aim of refining RPT methods and
exploring the feasibility of their use in multi-researcher, multi-site studies. The authors discuss the process of developing and
carrying out a study design and procedure for use by two researchers across two sites and with two populations, critically address
the effectiveness of the use of the method & procedure by two researchers, and discuss recommendations for future studies
employing similar designs and methods. The paper also presents preliminary analysis of the RPT data gathered as part of the study
and suggests avenues for further research.
Observation of oscillatory Raman gain associated with two-photon Rabi oscillations of nanofiber-coupled atoms
Authors: Liedl Christian , Pucher Sebastian , Schneeweiss Philipp , Yatsenko Leonid P , Rauschenbeutel Arno
Published: October 2022

Quantum emitters with a Λ-type level structure enable numerous protocols and applications in quantum science and technology. Understanding and controlling their dynamics is, therefore, one of the central research topics in quantum optics. Here, we drive two-photon Rabi oscillations between the two ground states of cesium atoms and observe the associated oscillatory Raman gain and absorption that stems from the atom-mediated coherent photon exchange between the two drive fields. The atoms are efficiently and homogeneously coupled with the probe field by means of a nanofiber-based optical interface. We study the dependence of the two-photon Rabi frequency on the system parameters and observe Autler–Townes splitting in the probe transmission spectrum. Beyond shedding light on the fundamental processes underlying two-photon Rabi oscillations, our method could also be used to investigate (quantum) correlations between the two drive fields as well as the dynamical establishment of electromagnetically induced transparency.
Effect and optimization of the Zn3P2 back surface field on the efficiency of CZTS/CZTSSe tandem solar cell: a computational approach
Authors: Bibi Baseerat , Farhadi Bita , Khan Asghar H M Noor Ul Huda , Rahman Waseem Ur , Liu Aimin
Published: October 2022

Copper zinc tin sulfide (CZTS) and copper zinc tin sulfo selenide (CZTSSe) kesterite minerals are nontoxic and abundant in the earth with the promise of cost-effective photovoltaic applications. This study explains a tandem solar cell made of kesterite materials that can capture sunlight over a broad spectrum. The proposed tandem structure comprises a wide bandgap CZTS thin-film upper subcell and an underlying narrow bandgap CZTSSe-based lower subcell. The upper and lower subcells are simulated using solar cell capacitance simulator-one dimension and validated against the experimental results to determine the viability of the proposed tandem design. Additionally, the performance of both subcells is evaluated for tandem configuration by adding a back surface field layer, a modification of the back contact, testing at different thicknesses, and doping of both subcell absorber layers. As a result, optimizing both subcells improved tandem solar cell open-circuit voltage (V
oc) to a maximum of 1.5 V, which led to an efficiency of 23.99% at the current matching condition. Furthermore, how light radiation power and temperature variations impact the proposed solar cell performance is being investigated. This study provides significant insights into efficient tandem solar cell design and manufacture.
Spin-transfer and spin-orbit torques in the Landau–Lifshitz–Gilbert equation
Authors: Meo Andrea , Cronshaw Carenza E , Jenkins Sarah , Lees Amelia , Evans Richard F L
Published: October 2022

Dynamic simulations of spin-transfer and spin-orbit torques are increasingly important for a wide range of spintronic devices including magnetic random access memory, spin-torque nano-oscillators and electrical switching of antiferromagnets. Here we present a computationally efficient method for the implementation of spin-transfer and spin-orbit torques within the Landau–Lifshitz–Gilbert equation used in micromagnetic and atomistic simulations. We consolidate and simplify the varying terminology of different kinds of torques into a physical action and physical origin that clearly shows the common action of spin torques while separating their different physical origins. Our formalism introduces the spin torque as an effective magnetic field, greatly simplifying the numerical implementation and aiding the interpretation of results. The strength of the effective spin torque field unifies the action of the spin torque and subsumes the details of experimental effects such as interface resistance and spin Hall angle into a simple transferable number between numerical simulations. We present a series of numerical tests demonstrating the mechanics of generalised spin torques in a range of spintronic devices. This revised approach to modelling spin-torque effects in numerical simulations enables faster simulations and a more direct way of interpreting the results, and thus it is also suitable to be used in direct comparisons with experimental measurements or in a modelling tool that takes experimental values as input.
Contactless skin perfusion monitoring with video cameras: tracking pharmacological vasoconstriction and vasodilation using photoplethysmographic changes
Authors: Harford M , Villarroel M , Jorge J , Redfern O , Finnegan E , Davidson S , Young J D , Tarassenko L , Watkinson P
Published: October 2022

Objectives. Clinical assessment of skin perfusion informs prognosis in critically ill patients. Video camera monitoring could provide an objective, continuous method to monitor skin perfusion. In this prospective, interventional study of healthy volunteers, we tested whether video camera-derived photoplethysmography imaging and colour measurements could detect drug-induced skin perfusion changes. Approach. We monitored the lower limbs of 30 volunteers using video cameras while administering phenylephrine (a vasoconstrictor) and glyceryl trinitrate (a vasodilator). We report relative pixel intensity changes from baseline, as absolute values are sensitive to environmental factors. The primary outcome was the pre- to peak- infusion green channel amplitude change in the pulsatile PPGi waveform component. Secondary outcomes were pre-to-peak changes in the photoplethysmographic imaging waveform baseline, skin colour hue and skin colour saturation. Main results. The 30 participants had a median age of 29 years (IQR 25–34), sixteen (53%) were male. A 34.7% (p = 0.0001) mean decrease in the amplitude of the pulsatile photoplethysmographic imaging waveform occurred following phenylephrine infusion. A 30.7% (p = 0.000004) mean increase occurred following glyceryl trinitrate infusion. The photoplethysmographic imaging baseline decreased with phenylephrine by 2.1% (p = 0.000 02) and increased with glyceryl trinitrate by 0.5% (p = 0.026). Skin colour hue changed in opposite direction with phenylephrine (−0.0013, p = 0.0002) and glyceryl trinitrate (+0.0006, p = 0.019). Skin colour saturation decreased with phenylephrine by 0.0022 (p = 0.0002), with no significant change observed with glyceryl trinitrate (+0.0005, p = 0.21). Significance. Drug-induced vasoconstriction and vasodilation are associated with detectable changes in photoplethysmographic imaging waveform parameters and skin hue. Our findings suggest video cameras have great potential for continuous, contactless skin perfusion monitoring.
Initial stages of pulsed discharge in saline solutions in a vicinity of threshold voltages
Authors: Korolev Y D , Landl N V , Bolotov A V , Kasyanov V S , Nekhoroshev V O , Shemyakin I A
Published: October 2022

Data are presented on an investigation of pulsed discharges in a solution of 30 g of NaCl per liter of distilled water. The interelectrode gap consists of the active pin electrode and the return plane electrode. The voltage pulse of positive polarity forms by means of an electric circuit where a capacitor bank of 40 μF with an initial voltage V
0 of up to 1500 V is discharged via the gap. In a range of initial voltages V
0 = (550 – 1100) V vapor cavities in a form of the microbubbles are generated near the active electrode and at the electrode surface. The microbubbles are able to merge with each other thus forming macrobubbles and vapor layers, which shield the active electrode from current passage. The process of vapor cavity generation and the effect of shielding are discussed in detail. The discharge at the vapor layer appears at the critical voltage V
0 = 1100 V. The principal prerequisite for discharge arising is that the electrode has to be completely shielded by the vapor layer and the voltage at the layer at the instant of discharge initiation has to be at least at a level of 500 V. However, when the voltage at the gap exceeds the critical value, the condition of complete shielding is not obligatory.
Reverse coating technique for the production of Nb thin films on copper for superconducting radio-frequency applications
Authors: Fonnesu D , Baris A , Calatroni S , Lain Amador L , Pfeiffer S , Rosaz G , Bonura M , Senatore C
Published: October 2022

In the framework of the Future Circular Collider Study, the development of thin-film coated superconducting radio-frequency copper cavities capable of providing higher accelerating fields (10–20 MV m−1 against 5 MV m−1 for the Large Hadron Collider) represents a major challenge. The method investigated here for the production of seamless niobium-coated copper cavities is based on the electroforming of the copper structure around a sacrificial aluminium mandrel that is pre-coated with a niobium thin film. The first feasibility study, applied to a flat aluminium disk mandrel, is presented. Protective precautions are taken towards the functional niobium film during the production process and it is shown that this technique can deliver well performing niobium films on a seamless copper substrate. This way, the non-trivial chemical treatments foreseen by the standard procedures (e.g. SUBU, EP) for the preparation of the copper surface to achieve the proper adhesion of the niobium layer are also avoided. The only major chemical treatment involved in the reverse-coating method is represented by the chemical dissolution of the aluminium mandrel, which has the advantage of not affecting the copper substrate and therefore the copper-niobium interface.
Effect of hexagonality on the pressure-dependent lattice dynamics of 4H-SiC
Authors: Zhang Junran , Liang Tao , Lu Yunhao , Xu Binjie , Deng Tianqi , Zhang Yiqiang , Zeng Zhidan , Pi Xiaodong , Yang Deren , Wang Rong
Published: October 2022

The pressure-dependent lattice dynamics of 4H-SiC is investigated using diamond anvil cell, and compared with those of 3C- and 6H-SiC. It is found that both the zone-center longitudinal optical (LO) and transverse optical (TO) modes shift to higher frequencies with the increase of the applied pressures. This indicates that polymorph transitions are unlikely to happen under the (quasi-)hydrostatic pressure. The LO–TO splitting is described well by the cubic function with respect to the applied pressure. A decrease in the LO–TO splitting is observed above 33 GPa. The change of transverse effective charge and thus the ionic character of 4H-SiC exhibits a cubic dependence on the pressure due to the nonequivalent lattice dynamics parallel and perpendicular to the c-axis of 4H-SiC. Compared to what happens in 6H-SiC, the high pressure exerts higher effect on the ionic character of 4H-SiC because less nonequivalent bilayers are evolved. At last, the mode-Grüneisen parameters of the LO and TO modes at the Γ point are determined. Given the hexagonal lattice of 4H-SiC, the LO mode are softer than the TO mode.
Tunable spatial Goos-Hänchen shift in periodic PT-symmetric photonic crystals with a central defect
Authors: Zhang Xiaoping , Zeng Xiangjin , Zhou Guopeng , Ni Hao
Published: October 2022

The Goos-Hänchen (GH) effects are investigated for a transverse magnetic beam totally reflected by periodic PT-symmetric photonic crystals. A dielectric layer with a real refractive index situates as a defect in the center. Both positive and negative spatial GH shifts are induced around the defect mode. The GH shifts sensitively change with the refractive index of the defect layer. More importantly, giant negative GH shift effect with big reflectance could be found and modulated by increasing the gain-loss factor in PT-symmetric systems, which could improve the detecting sensitivity of the defect. Our study may be valuable in potential applications for highly sensitive sensors.
Magnetohydrodynamic instabilities in a self-gravitating rotating cosmic plasma
Authors: Turi Jyoti , Misra A P
Published: October 2022

The generation of magnetohydrodynamic (MHD) waves and their instabilities are studied in galactic gaseous rotating plasmas with the effects of the magnetic field, the self gravity, the diffusion-convection of cosmic rays as well as the gas and cosmic-ray pressures. The coupling of the Jeans, Alfvén and magnetosonic waves, and the conditions of damping or instability are studied in three different cases, namely when the propagation direction is perpendicular, parallel and oblique to the static magnetic field, and are shown to be significantly modified by the effects of the Coriolis force due to the rotation of cosmic fluids and the cosmic-ray diffusion. The coupled modes can be damped or anti-damped depending on the wave number is above or below the Jeans critical wave number that is reduced by the effects of the Coriolis force and the cosmic-ray pressure. It is found that the deviation of the axis of rotation from the direction of the static magnetic field gives rise to the coupling between the Alfvén wave and the classical Jeans mode which otherwise results into the modified slow and fast Alfvén waves as well as the modified classical Jeans modes. Furthermore, due to the effects of the cosmic rays diffusion, there appears a new wave mode (may be called the fast Jeans mode) in the intermediate frequency regimes of the slow and fast Alfvén waves, which seems to be dispersionless in the long-wavelength propagation and has a lower growth rate of instability in the high density regimes of galaxies. The dispersion properties and the instabilities of different kinds of MHD waves reported here can play pivotal roles in the formation of various galactic structures at different length scales.
Field- and anisotropy-induced magnetic transitions and specific heat of one-dimensional XYZ ferromagnet with single-ion anisotropy
Authors: Pham Thao Huong
Published: October 2022

Functional integral method is used to study the field- and anisotropy-induced magnetic transitions, spin waves and the specific heat of a one-dimensional spin-S XYZ ferromagnet with the addition of the single-ion anisotropy in an oblique magnetic field. Field-induced critical lines that begin at quantum critical points and depend on the anisotropy are found. Besides, a double-peak structure in temperature-dependent behavior of the specific heat is observed. The position and height of these peaks can be adjusted by the anisotropy and by the magnetic field. From these results, the important role of thermal and quantum fluctuations is also discussed. Finally, we comment on comparing our results with experimental and other theoretical studies on quasi-one-dimensional anisotropic ferromagnets.
Bispectrum-window convolution via Hankel transform
Authors: Pardede Kevin , Rizzo Federico , Biagetti Matteo , Castorina Emanuele , Sefusatti Emiliano , Monaco Pierluigi
Published: October 2022

We present a method to perform the exact convolution of the model prediction for
bispectrum multipoles in redshift space with the survey window function. We extend a widely
applied method for the power spectrum convolution to the bispectrum, taking advantage of a
2D-FFTlog algorithm. As a preliminary test of its accuracy, we consider the toy model of a
spherical window function in real space. This setup provides an analytical evaluation of the
3-point function of the window, and therefore it allows to isolate and quantify possible
systematic errors of the method. We find that our implementation of the convolution in terms of a
mixing matrix shows differences at the percent level in comparison to the measurements from a very
large set of mock halo catalogs. It is also able to recover unbiased constraints on halo bias
parameters in a likelihood analysis of a set of numerical simulations with a total volume of
100 h
-3 Gpc3. For the level of accuracy required by these tests, the multiplication with the mixing
matrix is performed in the time of one second or less.
Improving automated diagnosis of epilepsy from EEGs beyond IEDs
Authors: Thangavel Prasanth , Thomas John , Sinha Nishant , Peh Wei Yan , Yuvaraj Rajamanickam , Cash Sydney S , Chaudhari Rima , Karia Sagar , Jing Jin , Rathakrishnan Rahul , Saini Vinay , Shah Nilesh , Srivastava Rohit , Tan Yee-Leng , Westover Brandon , Dauwels Justin
Published: October 2022

Objective. Clinical diagnosis of epilepsy relies partially on identifying interictal epileptiform discharges (IEDs) in scalp electroencephalograms (EEGs). This process is expert-biased, tedious, and can delay the diagnosis procedure. Beyond automatically detecting IEDs, there are far fewer studies on automated methods to differentiate epileptic EEGs (potentially without IEDs) from normal EEGs. In addition, the diagnosis of epilepsy based on a single EEG tends to be low. Consequently, there is a strong need for automated systems for EEG interpretation. Traditionally, epilepsy diagnosis relies heavily on IEDs. However, since not all epileptic EEGs exhibit IEDs, it is essential to explore IED-independent EEG measures for epilepsy diagnosis. The main objective is to develop an automated system for detecting epileptic EEGs, both with or without IEDs. In order to detect epileptic EEGs without IEDs, it is crucial to include EEG features in the algorithm that are not directly related to IEDs. Approach. In this study, we explore the background characteristics of interictal EEG for automated and more reliable diagnosis of epilepsy. Specifically, we investigate features based on univariate temporal measures (UTMs), spectral, wavelet, Stockwell, connectivity, and graph metrics of EEGs, besides patient-related information (age and vigilance state). The evaluation is performed on a sizeable cohort of routine scalp EEGs (685 epileptic EEGs and 1229 normal EEGs) from five centers across Singapore, USA, and India. Main results. In comparison with the current literature, we obtained an improved Leave-One-Subject-Out (LOSO) cross-validation (CV) area under the curve (AUC) of 0.871 (Balanced Accuracy (BAC) of 80.9%) with a combination of three features (IED rate, and Daubechies and Morlet wavelets) for the classification of EEGs with IEDs vs. normal EEGs. The IED-independent feature UTM achieved a LOSO CV AUC of 0.809 (BAC of 74.4%). The inclusion of IED-independent features also helps to improve the EEG-level classification of epileptic EEGs with and without IEDs vs. normal EEGs, achieving an AUC of 0.822 (BAC of 77.6%) compared to 0.688 (BAC of 59.6%) for classification only based on the IED rate. Specifically, the addition of IED-independent features improved the BAC by 21% in detecting epileptic EEGs that do not contain IEDs. Significance. These results pave the way towards automated detection of epilepsy. We are one of the first to analyze epileptic EEGs without IEDs, thereby opening up an underexplored option in epilepsy diagnosis.
Subject adaptation convolutional neural network for EEG-based motor imagery classification
Authors: Liu Siwei , Zhang Jia , Wang Andong , Wu Hanrui , Zhao Qibin , Long Jinyi
Published: October 2022

Objective. Deep transfer learning has been widely used to address the nonstationarity of electroencephalogram (EEG) data during motor imagery (MI) classification. However, previous deep learning approaches suffer from limited classification accuracy because the temporal and spatial features cannot be effectively extracted. Approach. Here, we propose a novel end-to-end deep subject adaptation convolutional neural network (SACNN) to handle the problem of EEG-based MI classification. Our proposed model jointly optimizes three modules, i.e. a feature extractor, a classifier, and a subject adapter. Specifically, the feature extractor simultaneously extracts the temporal and spatial features from the raw EEG data using a parallel multiscale convolution network. In addition, we design a subject adapter to reduce the feature distribution shift between the source and target subjects by using the maximum mean discrepancy. By minimizing the classification loss and the distribution discrepancy, the model is able to extract the temporal-spatial features to the prediction of a new subject. Main results. Extensive experiments are carried out on three EEG-based MI datasets, i.e. brain–computer interface (BCI) competition IV dataset IIb, BCI competition III dataset IVa, and BCI competition IV dataset I, and the average accuracy reaches to 86.42%, 81.71% and 79.35% on the three datasets respectively. Furthermore, the statistical analysis also indicates the significant performance improvement of SACNN. Significance. This paper reveals the importance of the temporal-spatial features on EEG-based MI classification task. Our proposed SACNN model can make fully use of the temporal-spatial information to achieve the purpose.
Forecasting psychogenic non-epileptic seizure likelihood from ambulatory EEG and ECG
Authors: Xiong Wenjuan , Kameneva Tatiana , Lambert Elisabeth , Cook Mark J , Richardson Mark P , Nurse Ewan S
Published: October 2022

Objective. Critical slowing features (variance and autocorrelation) of long-term continuous electroencephalography (EEG) and electrocardiography (ECG) data have previously been used to forecast epileptic seizure onset. This study tested the feasibility of forecasting non-epileptic seizures using the same methods. In doing so, we examined if long-term cycles of brain and cardiac activity are present in clinical physiological recordings of psychogenic non-epileptic seizures (PNES). Approach. Retrospectively accessed ambulatory EEG and ECG data from 15 patients with non-epileptic seizures and no background of epilepsy were used for developing the forecasting system. The median period of recordings was 161 h, with a median of 7 non-epileptic seizures per patient. The phases of different cycles (5 min, 1 h, 6 h, 12 h, 24 h) of EEG and RR interval (RRI) critical slowing features were investigated. Forecasters were generated using combinations of the variance and autocorrelation of both EEG and the RRI of the ECG at each of the aforementioned cycle lengths. Optimal forecasters were selected as those with the highest area under the receiver-operator curve (AUC). Main results. It was found that PNES events occurred in the rising phases of EEG feature cycles of 12 and 24 h in duration at a rate significantly above chance. We demonstrated that the proposed forecasters achieved performance significantly better than chance in 8/15 of patients, and the mean AUC of the best forecaster across patients was 0.79. Significance. To our knowledge, this is the first study to retrospectively forecast non-epileptic seizures using both EEG and ECG data. The significance of EEG in the forecasting models suggests that cyclic EEG features of non-epileptic seizures exist. This study opens the potential of seizure forecasting beyond epilepsy, into other disorders of episodic loss of consciousness or dissociation.
Introducing block-Toeplitz covariance matrices to remaster linear discriminant analysis for event-related potential brain–computer interfaces
Authors: Sosulski Jan , Tangermann Michael
Published: October 2022

Objective. Covariance matrices of noisy multichannel electroencephalogram (EEG) time series data provide essential information for the decoding of brain signals using machine learning methods. However, small datasets and high dimensionality make it hard to estimate these matrices. In brain–computer interfaces (BCI) based on event-related potentials (ERP) and a linear discriminant analysis (LDA) classifier, the state of the art covariance estimation uses shrinkage regularization. As this is a general covariance regularization approach, we aim at improving LDA further by better exploiting the domain-specific characteristics of the EEG to regularize the covariance estimates. Approach. We propose to enforce a block-Toeplitz structure for the covariance matrix of the LDA, which implements an assumption of signal stationarity in short time windows for each channel. Main results. An offline re-analysis of data collected from 213 subjects under 13 different event-related potential BCI protocols showed a significantly increased binary classification performance of this ‘ToeplitzLDA’ compared to shrinkage regularized LDA (up to 6 AUC points, p < 0.001) and Riemannian classification approaches (up to 2 AUC points, p < 0.001). In an unsupervised visual speller application, this improvement would translate to a relative reduction of spelling errors by 81% on average for 25 subjects. Additionally, aside from lower memory and reduced time complexity for LDA training, ToeplitzLDA proves to be robust against drastic increases of the number of temporal features. Significance. The proposed covariance estimation allows BCI researchers to improve classification rates and reduce calibration times of BCI protocols using event-related potentials and thus support the usability of corresponding applications. Its lower computational and memory needs could make it a valuable algorithm especially for mobile BCIs.
Machine Learning As Seed Image Identification Using Principal Component Analysis (PCA)
Authors: Laksmana Indra , Hendra  , Jamaluddin  , Trinovita Zuhara J , Riza Nurtam M , Amrizal  , Syelly Rosda
Published: October 2022

Plants can be identified using several variables, such as seeds’ shapes, colors, and sizes. However, several types of plants have close similarities to seed shapes. Therefore, additional characteristics are necessary to support the identification process. This study applied machine learning with the PCA method to identify plant species from seed shapes. The PCA simplifies the observed variables by reducing data dimensions and storing 75% of the information. The procedure did not eliminate too much important information while reducing data size and processing time. We collected 100 images of plant seeds similar to one another, such as sapodilla seeds, soursop, cucumber, star fruit, grape, melon, apple, lime, watermelon, and chili. A measurement system was designed using the K-Fold Cross Validation, and 10 tables of experimental results discovered a good level of accuracy of 83%. The Omission error occurred in the seeds of soursop, starfruit, grape, apple, lime, and watermelon while the most commission errors occurred in apple seeds (8 times).
Semi-Automatic Boom Sprayer Development for Corn Crop Protection
Authors: Putri Renny Eka , Aprilio Jimmy , Santosa  , Geraldo JP , Ade S
Published: October 2022

A semi-automatic boom sprayer was developed to make it easier for farmers to spray pesticides on corn plants. The study was conducted with two treatments at the corn age of 15 days and 30 days. A test was carried out by comparing the performance of the semi-automatic boom sprayer and the performance of the generally used knapsack sprayer. This research also involved evaluation in the laboratory, evaluation in the field, and economic analysis. From the results of technical tests on corn plants aged 15 days and 30 days, it can be concluded that the capacity of the semi-automatic boom sprayer was 0.318 ha/hour with an operator speed of 0.316 m/s. The tank capacity of the semi-automatic boom sprayer was larger than that of the knapsack sprayer. The spraying efficiency of the semi-automatic boom sprayer was greater than that of the knapsack sprayer, namely 86.033% vs. 85.269%, respectively.
Modification Of Gelamai Payakumbuh Through the Addition Of Yellow Pumpkin (Cucurbita Moschata Duch) And Improved Packaging
Authors: Ermiati Ermiati , Gusmalini Gusmalini
Published: October 2022

This study entitled “Modification of Gelamai Payakumbuh through the Addition Yellow Pumpkin (Cucurbita moschata) and Improved Packaging” was conducted in order to empower local roots based on the traditional foods of the Payakumbuh area and also incorporating it with proper packaging techniques using various types of packaging materials to extend product shelf life. The research objective is to diversify the product of processed pumpkin gelamai, a specialty food from the city of Payakumbuh. This involves determining the proper formulation in the manufacturing of gelamai with the addition of yellow pumpkin, as well as extending the shelf life of processed gelamai through treatment and packaging modifications. Research was carried out for six months at the Payakumbuh Erina Gelamai Company and the Laboratory of Food Microbiology at the State Food Chemistry and Agriculture Polytechnic of Payakumbuh. The design used in this laboratory study was a Complete Randomized Design (CRD) arranged in a factorial with two factors, where each treatment was repeated three times. The first factor was modification by the addition of pumpkin waluh at 10%, 20%, 30%, and 40%. While the second factor was the treatment of the packaging type by using polypropylene plastic, aluminum foil, dried banana leaves, dried corn leaves, and glassine paper. The results showed that the diversification of product in the manufacturing of processed pumpkin gelamai can enhance flavor, fat content, and extend shelf life. The addition of pumpkin in the production of gelamai can suppress the formation of free fatty acids and the oxidation process during the storage. The best treatment was found to be modification by the addition of 30% pumpkin with the use of aluminum foil packaging, which can extend shelf life for 20 days at room temperature.
The Adaptability of Trichoderma spp. in the Practicum Land of Politeknik Pertanian Negeri Payakumbuh and the Barrier Mechanism on Xanthomonas campestris pv.oryzae
Authors: Maulina Fri , Muflihayati
Published: October 2022

Trichoderma is a multifunctional fungus that is widely known and used as a biological control agent and a decomposer because of its ability to compete with pathogenic fungi and because it possesses cellulolytic enzymes that can decompose organic matters. This study was conducted to determine the presence and species of Trichoderma on the practicum land of Politeknik Pertanian Negeri Payakumbuh. The descriptive method was used to report the Trichoderma exploration conducted in two land locations, namely rice field and dry field. The exploration was not performed on a piece of land with healthy plants, but on one that has been used for >5 years. The results show that Trichoderma was found in both locations with the same percentage of presence of 20%. The species found was macroscopically and microscopically identified as Trichoderma harzianum. This antagonist agent demonstrated the ability to suppress Xantomonas campestris pv. oryzae by covering colonies of Xantomonas campestris pv. oryzae.
A Quality and Economic Analysis of Non-fermented Chocolate Seeds, Young Surian Leaves, and Ginger on Chocolate Drink Formulas
Authors: Novita Rilma , Kasim Anwar , Nurdin Hazli , Utama Rozi Satria , Putri Nela Eska
Published: October 2022

This study aims to obtain beverages that meet the quality requirements of chemical, microbiological, and sensory properties from a combination of non-fermented cocoa beans, young surian leaves, and ginger as natural ingredients widely available in Indonesia and to analyze the product’s financial feasibility. Sensory properties were analyzed using the hedonic scale method to find the best formula. The ANOVA test has shown that the beverage formulas have no significantly different aroma and flavor (the sig. (P) > 0.01) but have significantly different colors and appearance (the sig. (P) < 0.01). The chocolate drink has a quality of chemical, microbiological, and sensory properties; thus it potentially becomes a beverage rich in antioxidants. The financial feasibility analysis results agree with the BEP, NPV, Net B/C, and PBP and express that the beverage business is potentially conducted.