bluuebunny/crossref_metadata_2025_split huggingface dataset:
Silicon electro-optic micro-modulator fabricated in standard CMOS technology as components for all silicon monolithic integrated optoelectronic systems
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Authors: Xu Kaikai 
Published: March 2021

Abstract
In this paper, optoelectronic characteristics and related switching behavior of one monolithically integrated silicon light-emitting device (LED) with an interesting wavelength range of 400–900 nm are studied. Through the comparison of two types of geometry, Si avalanche-based LED and Si field-effect LED (Si FE LED), in the same device, we establish the dimensional dependence of the switching speed of the LED. Almost-linear modulation curve implies lower distortion is shown for the Si FE LED with light emission enhancement, and technology computer aided design (TCAD) simulations are in line with the experimental results. Our findings indicate that ON–OFF keying up to GHz frequencies should be feasible with such diodes. Potential applications should include Si FE LED integrated into the micro-photonic systems.
Microstructural analysis and electrical behaviours of co-sputtered W–Ag thin films with a tilted columnar architecture
Authors: Boukhalfa Houssem , Potin Valérie , Martin Nicolas 
Published: March 2021

Abstract
W–Ag thin films are produced by magnetron co-sputtering technique using glancing angle co-deposition configuration. Different samples are prepared with similar conditions (same pressure, thickness and tungsten target current) but with a variable Ag target current changing from 0 to 80 mA. The effect of the Ag target current on the film structure and electrical properties is investigated using scanning and transmission electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction and van der Pauw technique. Thin films with inclined columns are obtained and the columns section becomes more anisotropic for the films prepared with the lowest Ag target currents. The elemental composition of the films also changes as a function of the Ag target current, varying from tungsten-rich (at low current) to homogeneous (at high current). W–Ag thin films exhibit different crystallographic structures. If the fcc Ag phase is always present, the metastable A15 β-W is pointed out only at low Ag target current while at high current, only the bcc α-W phase is present. The microstructural analysis shows that the core of the columns is formed by W while Ag covers the columns as grains. Room temperature electrical resistivity decreases with Ag target current, whereas its anisotropy decreases. This behaviour correlates with the change in the columnar cross-section morphology.
Mechanism of transient stagnant formation in convection of binary mixtures
Authors: Kobayashi Kazuya U , Shinohara Ryoko , Kurita Rei 
Published: March 2021

Abstract
Two-dimensional convection rolls are usually stable near the critical Rayleigh number in single component fluids. However, in binary mixtures, it has been reported that the roll patterns become unstable over time and that stagnant domains are transiently formed. The formation of transient stagnant domains (TSD) occurs in systems where one component is more viscous than the other. Meanwhile, the mechanism of the TSD formation has been unclear yet. Here, we use experiments using well-mixed silicone oils and colloidal suspensions to show that the formation of transient stagnant regions is chiefly related to the concentration dependence of the kinematic viscosity rather than spatially averaged properties. Furthermore, we find that the concentration dependence of density is also related to the formation of stagnant regions. The coupling between density, viscosity and concentration fluctuations may play an important role for thermal convection in multi-component mixtures.
Enhancing the stability of polymer nanostructures via ultrathin oxide coatings for nano-optical device applications
Authors: Wang Yasi , Liu Peng , Shi Huimin , Dai Yutong , Zhang Jian , Zhang Jianmin , Hu Yueqiang , Duan Huigao , Chen Yiqin 
Published: March 2021

Abstract
Polymer nanostructures have drawn tremendous attention due to their wide applications in nanotechnology. However, the morphology of the polymer nanostructures is fragile under harsh conditions such as high-power irradiation and organic-solution environments during the fabrication or the measurement processes, significantly limiting their potential applications. In this work, we propose and demonstrate a simple approach to improve the stability of polymer nanostructures by coating a conformal ultrathin oxide film via atomic-layer deposition. Due to the refractory and dense coating of the oxide layer, the stability of polymer structures is enhanced by the prohibition of deformation occurrences from thermally induced reflow and organic solution. As a proof of concept, poly(methyl methacrylate) (PMMA) nanostructures coated with a sub-10-nm TiO2 layer are demonstrated, and the structures exhibit high temperature stability at 180 °C and good resistance to soluble damage from organic solutions. Subsequently, the mechanism of the improved thermal stability is analyzed via mechanical simulations. Such an effective approach is proposed to significantly broaden the application of polymer nanostructures as functional elements for optical structures/devices that require excellent thermal and chemical stability.
Skyrmion driven by rotary magnetic field on the surface of magnetic nanotube: a Monte Carlo study
Authors: Chi Xiaodan , Du An , Hu Yong 
Published: March 2021

Abstract
We report a Monte-Carlo simulation of the formation of skyrmions under a rotary magnetic field on a nanotube. The zero-field magnetic state is characterized as helical stripe domains swirling on the nanotube, with one to three periods depending on the ratio of Dzyaloshinskii–Moriya to ferromagnetic interaction and tubular size. Under a rotary magnetic field, the formation of skyrmions is in pair and the skyrmion number can be tuned. The movement of skyrmions is neither synchronous along with the rotary field, nor along a helical trajectory perpendicular to the rotary field. It is ascribed to that within a skyrmion pair, on one hand, the coupling between skyrmions is nonnegligible; on the other hand, different skyrmion pairs side by side are decoupled. This work predicts a way of nanotube-based skyrmion manipulation, and might develop the rotary information storage on energy- and space-saving modes or an edgeless racetrack memory.
Maxwellian mirages in general relativity
Authors: Williams L L , Inan N 
Published: March 2021

Abstract
Maxwellian approximations to linear general relativity are revisited in light of recent results on the degrees of freedom (DoF) in the linear gravitational field. The well-known Maxwellian formalism obtained in harmonic coordinates is compared with a Maxwellian formalism obtained under a coordinate choice where each of the metric components corresponds to each of the coordinate-invariant DoF of the linear gravitational field. The coordinate freedom of general relativity can be exploited to cast the field equations into Maxwellian form, but such forms can be mere mirages of the coordinate choice—mirages such as vector gravitational waves. A coordinate choice that yields perfectly-Maxwellian field equations, will yield a force equation that is not Lorentzian. If field definitions are chosen to obtain Lorentz-like terms in the force equation, then Maxwellian forms are compromised in the field equations. Many treatments of gravito-electromagnetism will make inconsistent ordering choices between the field equations and force equations, or else truncate terms of relevant order from the force equation. Often such mistakes reflect an attempt to force exact Maxwellian analogs simultaneously in both the field equations and the force equation, with the result that terms dropped are as large as those kept.
Degenerate solutions to the Dirac equation for massive particles and their applications in quantum tunneling
Authors: Tsigaridas Georgios N , Kechriniotis Aristides I , Tsonos Christos A , Delibasis Konstantinos K 
Published: March 2021

Abstract
In a recent work we have proven the existence of degenerate solutions to the Dirac equation, corresponding to an infinite number of different electromagnetic fields, providing also some examples regarding massless particles. In the present article our results are extended significantly, providing degenerate solutions to the Dirac equation for particles with arbitrary mass, which, under certain conditions, could be interpreted as pairs of particles (or antiparticles) moving in a potential barrier with energy equal to the height of the barrier and spin opposite to each other. We calculate the electromagnetic fields corresponding to these solutions, providing also some examples regarding both spatially constant electromagnetic fields and electromagnetic waves. Further, we discuss some potential applications of our work, mainly regarding the control of the particles outside the potential barrier, without affecting their state inside the barrier. Finally, we study the effect of small perturbations to the degenerate solutions, showing that our results are still valid, in an approximate sense, provided that the amplitude of the electromagnetic fields corresponding to the exact degenerate solutions is sufficiently small.
ANTARES upper limits on the multi-TeV neutrino emission from the GRBs detected by IACTs
Authors: Albert A. , André M. , Anghinolfi M. , Anton G. , Ardid M. , Aubert J.-J. , Aublin J. , Baret B. , Basa S. , Belhorma B. , Bertin V. , Biagi S. , Bissinger M. , Boumaaza J. , Bouta M. , Bouwhuis M.C. , Brânzaş H. , Bruijn R. , Brunner J. , Busto J. , Capone A. , Caramete L. , Carr J. , Carretero V. , Celli S. , Chabab M. , Chau T.N. , Cherkaoui El Moursli R. , Chiarusi T. , Circella M. , Coleiro A. , Colomer-Molla M. , Coniglione R. , Coyle P. , Creusot A. , Díaz A.F. , de Wasseige G. , Deschamps A. , Distefano C. , Di Palma I. , Domi A. , Donzaud C. , Dornic D. , Drouhin D. , Eberl T. , El Khayati N. , Enzenhöfer A. , Ettahiri A. , Fermani P. , Ferrara G. , Filippini F. , Fusco L. , García R. , Gay P. , Glotin H. , Gozzini R. , Graf K. , Guidi C. , Hallmann S. , van Haren H. , Heijboer A.J. , Hello Y. , Hernández-Rey J.J. , Hößl J. , Hofestädt J. , Huang F. , Illuminati G. , James C.W. , Jisse-Jung B. , de Jong M. , de Jong P. , Jongen M. , Kadler M. , Kalekin O. , Katz U. , Khan-Chowdhury N.R. , Kouchner A. , Kreykenbohm I. , Kulikovskiy V. , Lahmann R. , Le Breton R. , Lefèvre D. , Leonora E. , Levi G. , Lincetto M. , Lopez-Coto D. , Loucatos S. , Maderer L. , Manczak J. , Marcelin M. , Margiotta A. , Marinelli A. , Martínez-Mora J.A. , Mazzou S. , Melis K. , Migliozzi P. , Moser M. , Moussa A. , Muller R. , Nauta L. , Navas S. , Nezri E. , Nuñez-Castiñeyra A. , O'Fearraigh B. , Organokov M. , Păvălaş G.E. , Pellegrino C. , Perrin-Terrin M. , Piattelli P. , Pieterse C. , Poirè C. , Popa V. , Pradier T. , Randazzo N. , Reck S. , Riccobene G. , Sánchez-Losa A. , Samtleben D.F.E. , Sanguineti M. , Sapienza P. , Schnabel J. , Schüssler F. , Spurio M. , Stolarczyk Th. , Taiuti M. , Tayalati Y. , Thakore T. , Tingay S.J. , Vallage B. , Van Elewyck V. , Versari F. , Viola S. , Vivolo D. , Wilms J. , Zegarelli A. , Zornoza J.D. , Zúñiga J. 
Published: March 2021

Abstract
The first gamma-ray burst detections by Imaging Atmospheric
Cherenkov Telescopes have been recently announced: GRB 190114C,
detected by MAGIC, GRB 180720B and GRB 190829A, observed by
H.E.S.S. A dedicated search for neutrinos in space and time
coincidence with the gamma-ray emission observed by IACTs has been
performed using ANTARES data. The search covers both the prompt and
afterglow phases, yielding no neutrinos in coincidence with the
three GRBs studied. Upper limits on the energetics of the neutrino
emission are inferred. The resulting upper limits are several orders
of magnitude above the observed gamma-ray emission, and they do not
allow to constrain the available models.
Entanglement entropy of cosmological perturbations for S-brane Ekpyrosis
Authors: Brahma Suddhasattwa , Brandenberger Robert , Wang Ziwei 
Published: March 2021

Abstract
We calculate the entanglement entropy of scalar perturbations due to gravitational non-linearities present in any model of canonically-coupled, single-field ekpyrosis. Specifically, we focus on a recent model of improved ekpyrosis which is able to generate a scale-invariant power spectrum of curvature perturbations and gravitational waves as well as have a non-singular bounce due to an S-brane at the end of ekpyrotic contraction. By requiring that the entanglement entropy remians subdominant to the thermal entropy produced during reheating, we get an upper bound on the energy scale of the bounce.
Ray-tracing log-normal simulation for weak gravitational lensing: application
to the cross-correlation with galaxies
Authors: Makiya Ryu , Kayo Issha , Komatsu Eiichiro 
Published: March 2021

Abstract
We present an algorithm to self-consistently generate mock weak gravitational lensing convergence fields and galaxy distributions in redshift space. We generate three-dimensional cosmic density fields that follow a log-normal distribution, and ray-trace them to produce convergence maps. As we generate the galaxy distribution from the same density fields in a manner consistent with ray-tracing, the galaxy-convergence cross-power spectrum measured from the mock agrees with the theoretical expectation with high precision.
We use this simulation to forecast the quality of galaxy-shear cross-correlation measurements from the Subaru
Hyper Suprime-Cam (HSC) and Prime Focus Spectrograph (PFS) surveys.
We find that the nominal HSC and PFS surveys would detect the cross power spectra with signal-to-noise ratios of 20 and 5 at the lowest (z = 0.7) and highest (z = 2.2) redshift bins, respectively.
Energy conditions allow eternal inflation
Authors: Kontou Eleni-Alexandra , Olum Ken D. 
Published: March 2021

Abstract
Eternal inflation requires upward fluctuations of the energy in a
Hubble volume, which appear to violate the energy conditions. In
particular, a scalar field in an inflating spacetime should obey the
averaged null energy condition, which seems to rule out eternal
inflation. Here we show how eternal inflation is possible when energy
conditions (even the null energy condition) are obeyed. The critical
point is that energy conditions restrict the evolution of any single
quantum state, while the process of eternal inflation involves
repeatedly selecting a subsector of the previous state, so there is no
single state where the conditions are violated.
How warm are non-thermal relics? Lyman-α bounds on out-of-equilibrium dark matter
Authors: Ballesteros Guillermo , Garcia Marcos A.G. , Pierre Mathias 
Published: March 2021

Abstract
We investigate the power spectrum of Non-Cold Dark Matter (NCDM) produced in a state out of thermal equilibrium. We consider dark matter production from the decay of scalar condensates (inflaton, moduli), the decay of thermalized and non-thermalized particles, and from thermal and non-thermal freeze-in. For each case, we compute the NCDM phase space distribution and the linear matter power spectrum, which features a cutoff analogous to that for Warm Dark Matter (WDM). This scale is solely determined by the equation of state of NCDM. We propose a mapping procedure that translates the WDM Lyman-α mass bound to NCDM scenarios. This procedure does not require expensive ad hoc numerical computations of the non-linear matter power spectrum. By applying it, we obtain bounds on several NCDM possibilities, ranging from m
DM ≳ EeV for DM production from inflaton decay with a low reheating temperature, to sub-keV values for non-thermal freeze-in. We discuss the phenomenological implications of these results for specific examples which include strongly-stabilized and non-stabilized supersymmetric moduli, gravitino production from inflaton decay, Z' and spin-2 mediated freeze-in, and non-supersymmetric spin-3/2 DM.
Conversion of spin and orbital angular momentum in the third harmonic generation process in the bulk of an isotropic medium
Authors: Grigoriev K S , Diukov V A , Makarov V A 
Published: March 2021

Abstract
The interaction between spin and orbital components of the angular momentum of an elliptically polarized beam with helicoidal phase profile and arbitrary axially symmetric intensity profile in the third-harmonic generation process is investigated. The third-harmonic beam is generated in an isotropic medium with cubic nonlinearity within undepleted pump approximation. The conservation of the total projections of both the spin angular momentum and orbital angular momentum components in four-wave mixing is demonstrated for interacting waves.
Subject- and task-independent neural correlates and prediction of decision confidence in perceptual decision making
Authors: Fernandez-Vargas Jacobo , Tremmel Christoph , Valeriani Davide , Bhattacharyya Saugat , Cinel Caterina , Citi Luca , Poli Riccardo 
Published: March 2021

Abstract

Objective. In many real-world decision tasks, the information available to the decision maker is incomplete. To account for this uncertainty, we associate a degree of confidence to every decision, representing the likelihood of that decision being correct. In this study, we analyse electroencephalography (EEG) data from 68 participants undertaking eight different perceptual decision-making experiments. Our goals are to investigate (1) whether subject- and task-independent neural correlates of decision confidence exist, and (2) to what degree it is possible to build brain computer interfaces that can estimate confidence on a trial-by-trial basis. The experiments cover a wide range of perceptual tasks, which allowed to separate the task-related, decision-making features from the task-independent ones. Approach. Our systems train artificial neural networks to predict the confidence in each decision from EEG data and response times. We compare the decoding performance with three training approaches: (1) single subject, where both training and testing data were acquired from the same person; (2) multi-subject, where all the data pertained to the same task, but the training and testing data came from different users; and (3) multi-task, where the training and testing data came from different tasks and subjects. Finally, we validated our multi-task approach using data from two additional experiments, in which confidence was not reported. Main results. We found significant differences in the EEG data for different confidence levels in both stimulus-locked and response-locked epochs. All our approaches were able to predict the confidence between 15% and 35% better than the corresponding reference baselines. Significance. Our results suggest that confidence in perceptual decision making tasks could be reconstructed from neural signals even when using transfer learning approaches. These confidence estimates are based on the decision-making process rather than just the confidence-reporting process.
Decoding of semantic categories of imagined concepts of animals and tools in fNIRS
Authors: Rybář Milan , Poli Riccardo , Daly Ian 
Published: March 2021

Abstract

Objective. Semantic decoding refers to the identification of semantic concepts from recordings of an individual’s brain activity. It has been previously reported in functional magnetic resonance imaging and electroencephalography. We investigate whether semantic decoding is possible with functional near-infrared spectroscopy (fNIRS). Specifically, we attempt to differentiate between the semantic categories of animals and tools. We also identify suitable mental tasks for potential brain–computer interface (BCI) applications. Approach. We explore the feasibility of a silent naming task, for the first time in fNIRS, and propose three novel intuitive mental tasks based on imagining concepts using three sensory modalities: visual, auditory, and tactile. Participants are asked to visualize an object in their minds, imagine the sounds made by the object, and imagine the feeling of touching the object. A general linear model is used to extract hemodynamic responses that are then classified via logistic regression in a univariate and multivariate manner. Main results. We successfully classify all tasks with mean accuracies of 76.2% for the silent naming task, 80.9% for the visual imagery task, 72.8% for the auditory imagery task, and 70.4% for the tactile imagery task. Furthermore, we show that consistent neural representations of semantic categories exist by applying classifiers across tasks. Significance. These findings show that semantic decoding is possible in fNIRS. The study is the first step toward the use of semantic decoding for intuitive BCI applications for communication.
The improvement of visual object tracking using a combination between particle and correlation filter
Authors: Habibi Yabunayya , Muniri  
Published: March 2021

Abstract
One of the many challenging problems from computer vision is constructing robust object tracking from various problems and object conditions. Difficulties in tracking are more complex when an image sequence has many types of tracking problems such as background clutter, fast motion, occlusion, illumination variance, scale variance, motion blur, non-rigid object pattern, and another. Meanwhile, the task to build a novel approach which efficiently handle all tracking problems still in development step, especially supported by low computing time. We combine adaptive particle filters (APF) and discriminative correlation filters (DCF) to overcome more complex tracking problems so it can improve overall tracking accuracy. Our combination employs APF as the main framework and embeds DCF in it to estimate motion vector. However, this will make a double-edged knife where the utilization of two approaches together will make enlarged computing time. So, we also utilize leap-tracking as an alternative solution to reduce high computation time. Our testing uses 15 sets of benchmarks tracking datasets and 3 sets by ourselves with various tracking problems. The results show that our combination significantly improves tracking accuracy. Thus, the reducing of computational procedures efficiently will increases tracker speed without reduces accuracy and avoids identification errors.
Likelihood ratio test for the adequacy of a regression model when the noise is given by the Slepian field
Authors: Somayasa Wayan 
Published: March 2021

Abstract
In this paper we establish a non parametric likelihood ratio (LR) test procedure for testing the mean of a regression or additive model when the disturbance is represented by the Slepian field. By utilizing the Cameron-Martin-Girsanov formula and the fundamental theorem of projection, we get the likelihood estimator of the mean function under either H
0 or H
1 as the projection of the random observation. By applying the fundamental characteristic of the Slepian field for a typical size of the moving rectangle, it is shown under H
0 that the probability distribution of the test statistic belongs to the family of a central chi-square distributions, whereas under H
1 it is distributed as a noncentral chi-square. Furthermore, by simulating a type of Fourier model, the empirical power function of the test shows that the proposed test is consistent in the sense it maximizes the probability of the rejection when the model is not true.