bluuebunny/crossref_metadata_2025_split huggingface dataset:
A full-head model to investigate intra and extracochlear electric fields in cochlear implant stimulation
Authors: Callejón-Leblic M A , Lazo-Maestre M , Fratter A , Ropero-Romero F , Sánchez-Gómez S , Reina-Tosina J 
Published: June 2024

Abstract

Objective. Despite the widespread use and technical improvement of cochlear implant (CI) devices over past decades, further research into the bioelectric bases of CI stimulation is still needed. Various stimulation modes implemented by different CI manufacturers coexist, but their true clinical benefit remains unclear, probably due to the high inter-subject variability reported, which makes the prediction of CI outcomes and the optimal fitting of stimulation parameters challenging. A highly detailed full-head model that includes a cochlea and an electrode array is developed in this study to emulate intracochlear voltages and extracochlear current pathways through the head in CI stimulation. Approach. Simulations based on the finite element method were conducted under monopolar, bipolar, tripolar (TP), and partial TP modes, as well as for apical, medial, and basal electrodes. Variables simulated included: intracochlear voltages, electric field (EF) decay, electric potentials at the scalp and extracochlear currents through the head. To better understand CI side effects such as facial nerve stimulation, caused by spurious current leakage out from the cochlea, special emphasis is given to the analysis of the EF over the facial nerve. Main results. The model reasonably predicts EF magnitudes and trends previously reported in CI users. New relevant extracochlear current pathways through the head and brain tissues have been identified. Simulated results also show differences in the magnitude and distribution of the EF through different segments of the facial nerve upon different stimulation modes and electrodes, dependent on nerve and bone tissue conductivities. Significance. Full-head models prove useful tools to model intra and extracochlear EFs in CI stimulation. Our findings could prove useful in the design of future experimental studies to contrast FNS mechanisms upon stimulation of different electrodes and CI modes. The full-head model developed is freely available for the CI community for further research and use.
Global gyrokinetic study of density gradient driven instability in tokamaks: the ubiquitous mode
Authors: Choudhary Sagar , Chowdhury Jugal , M Gopal Krishna , Mahapatra Jagannath , Singh Amit K , Ganesh Rajaraman , Villard Laurent 
Published: June 2024

Abstract
The ubiquitous mode is investigated in the linear regime for the first time using a global gyrokinetic model. These modes are driven by the density gradient in trapped electron population but with mode frequency in the ion diamagnetic drift direction, in contrast to the conventional trapped electron mode. The dispersion relation is calculated along with the global mode structure. The ubiquitous mode is quite global although appears at a shorter wavelength (

1
2

k
y
2

ρ
i
2

>
1

). We show that the main driving mechanism is the density gradient and the temperature gradient has only a modest effect; the mode can persist at higher temperature gradient scenarios making it another possible channel of anomalous transport. The magnetic shear reduces the growth of the mode; while the electron to ion temperature ratio has a nonmonotonic effect on the mode growth rate—growth rate increases initially for the ubiquitous branch of the mode and decreases afterwards as the conventional trapped electron mode starts dominating. The role of safety factor and toroidicity is also analyzed. Finally, a mixing length-based estimation of transport is presented.
Addressing data scarcity using audio signal augmentation and deep learning for bolt looseness prediction
Authors: Chelimilla Nikesh , Chinthapenta Viswanath , Korla Srikanth 
Published: June 2024

Abstract
Deep learning models such as convolutional neural networks (CNNs) encounter challenges, including instability and overfitting, while predicting bolt looseness in data-scarce scenarios. In this study, we proposed a novel audio signal augmentation approach to classify bolt looseness in the event of data deficiency using CNN models. Audio signals at varied bolt torque conditions were extracted using the percussion method. Audio signal augmentation was performed using signal shifting and scaling strategies after segmenting the extracted audio signals. The unaugmented and augmented audio signals were transformed into scalograms using the continuous wavelet transform approach to train the CNN models. Upon training with augmented datasets, a promising improvement in the loss and accuracy of the CNN models in recognizing bolt looseness was noticed. One of the significant observations from the current study is that the implementation of audio signal augmentation improved the extrinsic generalization ability of the CNN models to classify bolt looseness. A maximum increase of 73.5% to identify bolt looseness in novel data was exhibited as compared to without augmentation. Overall, a maximum accuracy of 94.5% to classify bolt looseness in unseen data was demonstrated upon audio signal augmentation. In summary, the results affirm that the audio signal augmentation approach empowered the CNN models to predict bolt looseness in data-deficient scenarios accurately.
Role of blue-shift length in macroscopic properties of high-harmonic generation
Authors: Khokhlova Margarita , Strelkov Vasily 
Published: June 2024

Abstract
The production of brighter coherent XUV radiation by intense laser pulses through the process of high-harmonic generation (HHG) is one of the central challenges in contemporary nonlinear optics. We study the generation and spatial propagation of high harmonics analytically and via ab initio simulations. We focus on the length scales defining the growth of the harmonic signal with propagation distance and show that the well-known coherence length limits HHG only for relatively low driving intensities. For higher intensities, the photoionisation of the medium, naturally accompanying HHG, leads to essentially transient phase matching and laser frequency blue shift. By systematically taking both of these factors into account, we demonstrate that the behaviour of the harmonic signal at higher intensities is defined by another length scale—the blue-shift length. In this generation regime the XUV intensity at a given frequency first grows quadratically and then saturates passing the blue-shift length, but the total harmonic efficiency continues growing linearly due to the linear increase of the harmonic line bandwidth. The changeover to this generation regime takes place for all harmonic orders roughly simultaneously. The rate of the efficiency growth is maximal if the atomic dispersion is compensated by photoelectrons near the centre of the laser pulse. Our theory offers a robust way to choose the generation conditions that optimise the growth of the harmonic signal with propagation.
Nonequilibrium quantum heat transport between structured environments
Authors: Pleasance Graeme , Petruccione Francesco 
Published: June 2024

Abstract
We apply the hierarchical equations of motion technique to analyzing nonequilibrium heat transport in a spin-boson type model, whereby heat transfer through a central spin is mediated by an intermediate pair of coupled harmonic oscillators. The coupling between each pair of oscillators is shown to introduce a localized gap into the effective spectral densities characterizing the system–oscillator–reservoir interactions. Compared to the case of a single mediating oscillator, we find the heat current to be drastically modified at weak system-bath coupling. In particular, a second-order treatment fails to capture the correct steady-state behavior in this regime, which stems from the λ
4-scaling of the energy transfer rate to lowest order in the coupling strength λ. This leads naturally to a strong suppression in the steady-state current in the asymptotically weak coupling limit. On the other hand, the current noise follows the same scaling as in the single oscillator case in accordance with the fluctuation-dissipation theorem. Additionally, we find the heat current to be consistent with Fourier’s law even at large temperature bias. Our analysis highlights a novel mechanism for controlling heat transport in nanoscale systems based on tailoring the spectral properties of thermal environments.
DFT calculations of new Li-based halides Li2AgAlY6 (Y = Cl, Br, I) for energy conversion applications
Authors: Tanveer Wasif , Adeel Abbas Syed , Noor N A , Alanazi Yousef Mohammed , Mumtaz Sohail 
Published: June 2024

Abstract
Recently, lead-free halide double perovskite (DP) materials have got scholarly attention owing to their environmentally sustainable characteristic, excellent stability and potential applications in solar cells and renewable energy. In this present article, we computationally examined the mechanical, optoelectronic and thermoelectric characteristics of a discernible compound Li2AgAlY6 (Y = Cl, Br, I) using the density functional theory (DFT). The evaluation of tolerance factor (tf), lattice constant (a0), and formation enthalpy (Hf) confirms the structural and thermodynamic stability of the investigated double DPs, also elastic constants further elaborate the mechanically stable nature. The studied compounds have direct band gap of 3.6 eV, 2.6 eV and 1.2 eV for Li2AgAlCl6, Li2AgAlBr6 and Li2AgAlI6 respectively, indicating the diverse energy absorption applications from ultraviolet to visible region. We used semi-classical Boltzman theory to determine the figure of merit (ZT) and corresponding Seebeck Coefficient (S), which validates the electrical and thermoelectric conductivity for the compounds under investigation. The current investigation establishes a theoretical foundation for the examined DPs, essential for comprehending and comparing forthcoming experimental inquiries aimed at exploring diverse optoelectronic and thermoelectric applications.
Effects of axial and radial components of magnetic field on the electromagnetic resistive instabilities in hall thruster plasma
Authors: Bharti Saty Prakash , Singh Sukhmander 
Published: June 2024

Abstract
A theoretical model is developed to investigate the effect of the axial component of the magnetic field on the electromagnetic resistive instabilities in the Hall thruster. The axial component of the magnetic field plays a vital role in controlling the plasma flow and generating thrust in the Hall thruster. It also affects the magnetic topology and magnetic field lines in the Hall thruster. In the present paper, a dispersion relation for the electromagnetic resistive instabilities under the influence of the axial component of the magnetic field is derived. The obtained dispersion equation is solved numerically to study the propagating and growing waves in the magnetized plasmas. It is observed that the growth rate decreases with an axial component of the magnetic field, but it increases with a radial component of the magnetic field. When the axial component of the magnetic field is considered, the amplitude of the growth rate of the resistive instability dropped with azimuthal wavenumber, collision frequency and electron drift velocity by almost 21%, 35%, and 33%, respectively. When the value of drift velocity exceeds 4 ×106 m s−1, the influence of the axial component of the magnetic field appeared, and the growth rate reduced drastically.
The dielectric and radiation shielding features of Zn0.9Ni0.1Co2-xFexO4 nanopowder
Authors: Heiba Zein K , Arafat Shadia W , Badawi Ali , Mohamed Mohamed Bakr 
Published: June 2024

Abstract
Nano Zn0.9Ni0.1Co2-xFexO4 (x = 0, 0.05, 0.1, 0.15) specimens were synthesized utilizing the hydrothermal method. An extensive assessment was conducted on the structure and dielectric characteristics of the fabricated specimens. The synchrotron x-ray diffraction and scanning electron microscopy techniques were employed to analyze the formed phases and the morphological characteristics of the specimens. Rietveld refinement was utilized for determining the structural and microstructural parameters of all specimens. The impact of temperature and frequency on the dielectric properties of the material is thoroughly investigated. Except for the specimen with x = 0.15, all samples exhibit ferroelectric characteristics. The electric modulus corroborated the existence of the non-Debye relaxation phenomenon and the presence of relaxation times distributed at a specific frequency. Each specimen demonstrates a singular relaxation time, which was modified by the introduction of Fe ions. Through the utilization of the Phy-X/PSD software, the radiation shielding parameters for the examined specimens were computed across a wide energy spectrum ranging from 15 KeV to 15 MeV. These parameters encompass the linear attenuation coefficients (LAC), mean free path (MFP), mass attenuation coefficient (MAC), half value length (HVL), effective nuclear number (Z
eff), and fast neutron removal cross-section (FNRCS). The specimens of Zn0.9Ni0.1Co2-xFexO4 exhibit elevated FNRCS values compared to RS-253-G18, RS-360, and RS-520 commercial shielding glasses.
DISCO-DJ I: a differentiable Einstein-Boltzmann solver for cosmology
Authors: Hahn Oliver , List Florian , Porqueres Natalia 
Published: June 2024

Abstract
We present the Einstein-Boltzmann module of the Disco-Dj (DIfferentiable Simulations for COsmology — Done with J
ax) software package. This module implements a fully differentiable solver for the linearised cosmological Einstein-Boltzmann equations in the Jax framework, and allows computing Jacobian matrices of all solver output with respect to all input parameters using automatic differentiation. This implies that along with the solution for a given set of parameters, the tangent hyperplane in parameter space is known as well, which is a key ingredient for cosmological inference and forecasting problems as well as for many other applications. We discuss our implementation and demonstrate that our solver agrees at the per-mille level with the existing non-differentiable solvers Camb and Class, including massive neutrinos and a dark energy fluid with parameterised equation of state. We illustrate the dependence of various summary statistics in large-scale structure cosmology on model parameters using the differentiable solver, and finally demonstrate how it can be easily used for Fisher forecasting, with a forecast for Euclid as an example. Since the implementation is significantly shorter and more modular than existing solvers, we believe it will be more straightforward to extend our solver to include additional physics, such as additional dark energy and dark matter models, modified gravity, or other non-standard physics in the future.
Stability of ECoG high gamma signals during speech and implications for a speech BCI system in an individual with ALS: a year-long longitudinal study
Authors: Wyse-Sookoo Kimberley , Luo Shiyu , Candrea Daniel , Schippers Anouck , Tippett Donna C , Wester Brock , Fifer Matthew , Vansteensel Mariska J , Ramsey Nick F , Crone Nathan E 
Published: June 2024

Abstract

Objective. Speech brain–computer interfaces (BCIs) have the potential to augment communication in individuals with impaired speech due to muscle weakness, for example in amyotrophic lateral sclerosis (ALS) and other neurological disorders. However, to achieve long-term, reliable use of a speech BCI, it is essential for speech-related neural signal changes to be stable over long periods of time. Here we study, for the first time, the stability of speech-related electrocorticographic (ECoG) signals recorded from a chronically implanted ECoG BCI over a 12 month period. Approach. ECoG signals were recorded by an ECoG array implanted over the ventral sensorimotor cortex in a clinical trial participant with ALS. Because ECoG-based speech decoding has most often relied on broadband high gamma (HG) signal changes relative to baseline (non-speech) conditions, we studied longitudinal changes of HG band power at baseline and during speech, and we compared these with residual high frequency noise levels at baseline. Stability was further assessed by longitudinal measurements of signal-to-noise ratio, activation ratio, and peak speech-related HG response magnitude (HG response peaks). Lastly, we analyzed the stability of the event-related HG power changes (HG responses) for individual syllables at each electrode. Main Results. We found that speech-related ECoG signal responses were stable over a range of syllables activating different articulators for the first year after implantation. Significance. Together, our results indicate that ECoG can be a stable recording modality for long-term speech BCI systems for those living with severe paralysis. Clinical Trial Information. ClinicalTrials.gov, registration number NCT03567213.
A machine learning artefact detection method for single-channel infant event-related potential studies
Authors: Marchant Simon , van der Vaart Marianne , Pillay Kirubin , Baxter Luke , Bhatt Aomesh , Fitzgibbon Sean , Hartley Caroline , Slater Rebeccah 
Published: June 2024

Abstract

Objective. Automated detection of artefact in stimulus-evoked electroencephalographic (EEG) data recorded in neonates will improve the reproducibility and speed of analysis in clinical research compared with manual identification of artefact. Some studies use very short, single-channel epochs of EEG data with little recorded EEG per infant—for example because the clinical vulnerability of the infants limits access for recording. Current artefact-detection methods that perform well on adult data and resting-state and multi-channel data in infants are not suitable for this application. The aim of this study was to create and test an automated method of detecting artefact in single-channel 1500 ms epochs of infant EEG. Approach. A total of 410 epochs of EEG were used, collected from 160 infants of 28–43 weeks postmenstrual age. This dataset—which was balanced to include epochs of background activity and responses to visual, auditory, tactile and noxious stimuli—was presented to seven independent raters, who independently labelled the epochs according to whether or not they were able to visually identify artefacts. The data was split into a training set (340 epochs) and an independent test set (70 epochs). A random forest model was trained to identify epochs as either artefact or not artefact. Main results. This model performs well, achieving a balanced accuracy of 0.81, which is as good as manual review of data. Accuracy was not significantly related to the infant age or type of stimulus. Significance. This method provides an objective tool for automated artefact rejection for short epoch, single-channel EEG in neonates and could increase the utility of EEG in neonates in both the clinical and research setting.
Rotational and translational dynamics and rheology in a granular system
Authors: Espinosa-Rodríguez José , Díaz-Leyva Pedro , Sánchez Rodrigo 
Published: June 2024

Abstract
The present work examines the translational and rotational dynamics, as well as their implications for system rheology, of an experimental granular system at an agitated air/water interface. A decoupling of rotational and translational dynamics is found. The translational dynamics is well-described by a modified Voigt model compatible to that obtained for prior simulational work, whereas the rotational motion alternates between two distinct states. The latter behaviour is accounted for in terms of collective effects at the edges.
Bethe M-layer construction on the Ising model
Authors: Angelini Maria Chiara , Palazzi Saverio , Parisi Giorgio , Rizzo Tommaso 
Published: June 2024

Abstract
In statistical physics, one of the standard methods to study second order phase transitions is the renormalization group that usually leads to an expansion around the corresponding fully connected solution. Unfortunately, often in disordered models, some important finite dimensional second-order phase transitions are qualitatively different or absent in the corresponding fully connected model: in such cases the standard expansion fails. Recently, a new method, the M-layer one, has been introduced that performs an expansion around a different soluble mean field model: the Bethe lattice one. This new method has been already used to compute the upper critical dimension

D
U

of different disordered systems such as the Random Field Ising model or the Spin glass model with field. If then one wants to go beyond and construct an expansion around

D
U

to understand how critical quantities get renormalized, the actual computation of all the numerical factors is needed. This next step has still not been performed, being technically more involved. In this paper we perform this computation for the ferromagnetic Ising model without quenched disorder, in finite dimensions: we show that, at one-loop order inside the M-layer approach, we recover the continuum quartic field theory and we are able to identify the coupling constant g and the other parameters of the theory, as a function of macroscopic and microscopic details of the model such as the lattice spacing, the physical lattice dimension and the temperature. This is a fundamental step that will help in applying in the future the same techniques to more complicated systems, for which the standard field theoretical approach is impracticable.
Advancements and Challenges in Linear Friction Welding of Inconel 718: A Comprehensive Review
Authors: Pawade Sneha , Raut Laukik , Biradar Akash , Bhushan Abhishek , Kolhe Mohini 
Published: June 2024

Abstract
This comprehensive review explores the linear friction welding of Inconel 718, a super alloy widely employed in aerospace and other high-temperature applications. Delving into the intricate relationship between process parameters and material properties, the paper examines microstructural transformations and their impact on mechanical integrity. Discussions encompass weldability, common defects, and mitigation strategies, providing valuable insights for practitioners. The review also highlights the evolving landscape of research trends, recent developments, and real-world applications, showcasing the versatility of linear friction welding. Challenges in the process are analyzed, offering a nuanced perspective on current limitations and avenues for improvement. Through a comparative lens with traditional welding techniques, the paper elucidates the unique advantages of linear friction welding in enhancing efficiency and performance. This synthesis of knowledge contributes to a holistic understanding of the state-of-the-art in linear friction welding of Inconel 718, presenting opportunities for future advancements in this critical domain.