bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimized x-ray emission from 10 ns long germanium x-ray sources at the National Ignition Facility
Authors: Werellapatha K. , Hall G. N. , Krauland C. , Krygier A. , Bhandarkar N. , Bradley D. K. , Coppari F. , Gorman M. G. , Heinbockel C. , Kemp G. E. , Khan S. F. , Lazicki A. , Masters N. , May M. J. , Nagel S. R. , Palmer N. E. , Eggert J. H. , Benedetti L. R. 
Published: December 2022

This study investigates methods to optimize quasi-monochromatic, ∼10 ns long x-ray sources (XRS) for time-resolved x-ray diffraction measurements of phase transitions during dynamic laser compression measurements at the National Ignition Facility (NIF). To support this, we produce continuous and pulsed XRS by irradiating a Ge foil with NIF lasers to achieve an intensity of 2 × 1015 W/cm2, optimizing the laser-to-x-ray conversion efficiency. Our x-ray source is dominated by Ge He-α line emission. We discuss methods to optimize the source to maintain a uniform XRS for ∼10 ns, mitigating cold plasma and higher energy x-ray emission lines.
Mapping the self-generated magnetic fields due to thermal Weibel instability
Authors: Zhang Chaojie , Wu Yipeng , Sinclair Mitchell , Farrell Audrey , Marsh Kenneth A. , Petrushina Irina , Vafaei-Najafabadi Navid , Gaikwad Apurva , Kupfer Rotem , Kusche Karl , Fedurin Mikhail , Pogorelsky Igor , Polyanskiy Mikhail , Huang Chen-Kang , Hua Jianfei , Lu Wei , Mori Warren B. , Joshi Chan 
Published: December 2022

The origin of the seed magnetic field that is amplified by the galactic dynamo is an open question in plasma astrophysics. Aside from primordial sources and the Biermann battery mechanism, plasma instabilities have also been proposed as a possible source of seed magnetic fields. Among them, thermal Weibel instability driven by temperature anisotropy has attracted broad interests due to its ubiquity in both laboratory and astrophysical plasmas. However, this instability has been challenging to measure in a stationary terrestrial plasma because of the difficulty in preparing such a velocity distribution. Here, we use picosecond laser ionization of hydrogen gas to initialize such an electron distribution function. We record the 2D evolution of the magnetic field associated with the Weibel instability by imaging the deflections of a relativistic electron beam with a picosecond temporal duration and show that the measured

k

-resolved growth rates of the instability validate kinetic theory. Concurrently, self-organization of microscopic plasma currents is observed to amplify the current modulation magnitude that converts up to ~1% of the plasma thermal energy into magnetic energy, thus supporting the notion that the magnetic field induced by the Weibel instability may be able to provide a seed for the galactic dynamo.
Thekopsora minima (Arthur) Syd. & Syd. [Distribution map].
Authors: CABI  , EPPO  
Published: December 2022

Abstract

A new distribution map is provided for Thekopsora minima (Arthur) Syd. & Syd. Pucciniomycetes: Pucciniales: Pucciniastraceae. Main hosts: blueberry (
Vaccinium corymbosum
), bilberry (
V. myrtillus
), alternate host, hemlock (mostly
Tsuga canadensis
).
Ceratocystis ficicola Kajitani & Masuya. [Distribution map].
Authors: CABI  , EPPO  
Published: December 2022

Abstract

A new distribution map is provided for Ceratocystis ficicola Kajitani & Masuya. Sordariomycetes: Microascales: Ceratocystidaceae. Host: fig (
Ficus carica
), Ficus benjamina.
The
C∞
-isomorphism property for a class of singularly-weighted x-ray transforms
Authors: Mishra Rohit Kumar , Monard François , Zou Yuzhou 
Published: December 2022

Abstract
We study a one-parameter family of self-adjoint normal operators for the x-ray transform on the closed Euclidean disk

D

, obtained by considering specific singularly weighted L
2 topologies. We first recover the well-known singular value decompositions in terms of orthogonal disk (or generalized Zernike) polynomials, then prove that each such realization is an isomorphism of

C
∞

(

D

)

. As corollaries: we give some range characterizations; we show how such choices of normal operators can be expressed as functions of two distinguished differential operators. We also show that the isomorphism property also holds on a class of constant-curvature, circularly symmetric simple surfaces. These results allow to design functional contexts where normal operators built out of the x-ray transform are provably invertible, in Fréchet and Hilbert spaces encoding specific boundary behavior.
Q-switching of an optical tweezer phonon laser
Authors: Xiao Kewen , Pal Arpita , Sharma Sandeep , Pettit R M , Vamivakas A N , Bhattacharya M 
Published: December 2022

Abstract
We theoretically investigate the active Q-switching of an optical tweezer phonon laser Pettit et al (2019 Nat. Photon.
13 402) operating in a coupled-mode configuration. One of the modes is lasing and outcouples to the second mode. The coupling is induced via asymmetric modulation of the trap potential in the transverse plane of the trapped nanoparticle. We show that a time-modulated coherent coupling between two transverse modes of oscillation of an optically levitated nanoparticle holds the key to coherent pulsed phonon transfer between them. Our analytical and numerical results on the position dynamics, phonon dynamics as well as second-order coherence confirms pulsed phonon lasing transfer between the transverse modes. Our work on Q-switched operation of the optical tweezer phonon laser enhances understanding of the analogies between optical and mechanical lasers, and is relevant to levitated phonon transport, acoustic imaging, sensing and information processing technologies.
Numerical simulation of the ignition law for a hot bridge wire electroexplosive device
Authors: Lyu Xuxu , Wei Guanghui , Du Xue , Zhao Hongze , Sun Jiangning 
Published: December 2022

Abstract
Hot bridge wire electroexplosive devices (EEDs) are widely used as starting elements in aerospace and other fields. Their thermal ignition process and safety testing technology have always been a focus of research. In this paper, we construct a temperature rise model for a hot bridge wire EED by using the law of conservation of energy, and the temperature response of the bridge wire and the reagent is obtained. According to the theoretical and numerical analysis, the sensitive criterion for a hot bridge wire EED is given, and the simulation process for the critical ignition current is designed. Based on this process, the law of the influence of the bridge wire and reagent parameters on the ignition of a hot bridge wire EED was studied. The research results show that a first derivative of the reagent temperature with respect to the radial distance of greater than zero is a sensitive criterion for the ignition of a hot bridge wire EED with high accuracy. Compared with traditional numerical methods, the proposed process makes the acquisition of the critical ignition current more precise and programmable due to the use of sensitive criteria. In addition, the following significant features are noted: the critical ignition current first increases as the square root of the bridge wire radius and then linearly; the square of the critical ignition current increases linearly with the activation energy of the reagent; there is rapid exponential decay of the critical ignition current with increasing reagent combustion heat; asymptotic values are present. In engineering use, it is possible to conveniently design the ignition characteristics of a hot bridge wire EED by changing the radius of the bridge wire. This study serves as a foundational work for the safety testing of hot bridge wire EEDs and can provide theoretical guidance for the safety testing, actual production and use of hot bridge wire EEDs.
A novel ensemble convex hull-based classification model for bevel gearbox fault diagnosis
Authors: Kang Xin , Cheng Junsheng , Wang Ping , Wang Jian , Zhu Zuanyu , Yang Yu 
Published: December 2022

Abstract
The kernel-based geometric learning model has been successfully applied in bevel gearbox fault diagnosis. However, due to its shallow architecture and problems with its sensitivity to noise and outliers, its generalization ability and robustness need to be further improved. Ensemble learning can improve the classification accuracy of sub-classifiers, but it is effective only when the sub-classifiers meet the requirements of difference and accuracy at the same time. However, as strong classifiers, geometric learning models are difficult to produce sub-classifiers with differences. To solve these problems, this study proposes a novel ensemble model, the ensemble convex hull (CH)-based (EnCH) classification model. CH has the advantages of clear geometric meaning and is easy to deform. This paper considers the clustering characteristics of the sample points in the feature space, or both distance and density, and performs differential shrinkage deformation on the original CH. For one thing, this can produce differential CHs to build differential sub-classifiers for the ensemble. Also, it can suppress the interference of noise and outliers to improve robustness. The results of our experiments on the fault dataset of a bevel gear box indicate that the EnCH classification model can improve the generalization of the geometric learning model and has excellent tolerance to noise and outliers.
Characterisation, modelling and design of cut-off wavelength of InGaAs/GaAsSb type-II superlattice photodiodes
Authors: Petticrew Jonathan , Ji Yuting , Han Im Sik , White Benjamin , Evirgen Axel , Reverchon Jean-Luc , Hopkinson Mark , Tan Chee Hing , Ng Jo Shien 
Published: December 2022

Abstract
InGaAs/GaAsSb type-II superlattice (T2SL) photodiodes grown on InP substrates are an alternative detector technology for applications operating in the short wavelength infrared band. Their cut-off wavelengths are heavily influenced by the thickness and material composition of InGaAs and GaAsSb used in the T2SL. We present a single band k.p. model performed using a finite difference approach in nextnano validated against two T2SL photodiode wafers and results from literature. These photodiode wafers cover both lattice matched and strained GaAs1−x
Sb
x
compositions (x = 0.40, wafer A and 0.49, wafer B). The validation data covers temperature dependence of cut-off wavelengths (obtained from phase-sensitive photo response data) from 200 K to room temperature. The cut-off wavelengths were found to reduce at 1.32 nm K−1 for wafer A and 1.07 nm K−1 for wafer B. Good agreement was achieved between the validation data and nextnano simulations, after altering the GaAs1−x
Sb
x
valance band offset (VBO) bowing parameter to −1.06 eV. Using this validated model, we show that the wavefunction overlap drops significantly if the GaAsSb barrier is thicker than the InGaAs well layer, hence defining the upper limit of the barrier layer. This validated model is then used to demonstrate that there is a linear dependence between the maximum achievable wavefunction overlap and cut-off wavelength of a lattice matched InGaAs/GaAsSb T2SL. We also found that the adoption of a 5 nm/3 nm InGaAs/GaAsSb T2SL structure offers an improved wavefunction overlap over the more common 5 nm/5 nm InGaAs/GaAsSb T2SL designs. The data reported in this paper is available from doi: 10.15131/shef.data.20310591.
The interplay of process parameters and influence on the AlN films on sapphire fabricated by DC magnetron sputtering and annealing
Authors: Liu Huan , Guo Wei 
Published: December 2022

Abstract
This paper reports a high-quality aluminium nitride (AlN) film deposited on c-plane sapphire using a direct current reactive sputtering system. A comprehensive investigation on the effects of substrate temperature, sputtering power, Ar/N2 flow ratio, and process pressure on the morphology and crystalline quality of the AlN thin films was performed. Optimal process parameters including substrate temperature of 500 °C, process pressure of 0.5 Pa, gas flow ratio of Ar/N2 = 1/6, and sputtering power of 400 W was demonstrated. In addition, the crystallization quality was further improved after face-to-face annealing and homoepitaxial regrowth by metal–organic chemical vapor deposition. The full widths at half maximum values of the x-ray rocking curves of the (0002) and (

10

1
ˉ

2

) diffraction of AlN after the re-growth process reach as low as 49 and 360 arcsec, respectively, and the corresponding surface morphologies of the films were covered with atomic bi-layer steps. Finally, a ultraviolet-C light emitting diode with decent performance was demonstrated on top of the sputtered AlN thin film.
Effect of branched structure on microphase separation and electric field induced bending actuation behaviors of poly(urethane–urea) elastomers
Authors: Zeng Haibing , Fu Silian , Liang Yongri , Liu Li 
Published: December 2022

Abstract
Polyurethane elastomers as a type of electroactive polymers have wide applications in soft actuators, soft sensors and energy harvesting due to their high dielectric constant, high electrostriction coefficients, easy processing and structure adjustability, and superior biocompatibility etc. However, the relationship between microstructure and electromechanical properties of EAEs has not been fully understood. In this work, we fabricated the branch structured poly(urethane–urea) elastomers (PUUs) using hydroxy-terminated polybutadiene as soft segment, isophorone diisocyanate and 4,4-diaminodicyclohexylmethane as hard segment, and hydroxyl-terminated four-armed polycaprolactone (PCL410) as branch structured chain extender for improving bending actuation performances, and understanding the relationship between structure and electromechanical properties. The degree of branched structure of PUUs were adjusted by the content of PCL410. The microphase separation kinetics of PUUs was enhanced as increase of PCL410 content, whereas the degree of microphase separation and hard domain size of PUUs were reduced. The mechanical loss and bending actuation stress of PUUs were significantly improved by incorporation of small amount of branched structure into PUU chains. The PUU with 2.60 mol.% of PCL410 showed 5.16 mm of bending displacement and 5.16 Pa of bending actuation stress at 7.2 kV (corresponding to 180 V mm−1 of the nominal electric field), which were 76.3, and 79 times higher than that of PUU without PCL410, respectively. The electric field induced bending actuation mechanism of branch structured PUUs was suggested that the bending actuation mechanism of branch structured PUUs is caused by electrostrictive effect from dipole orientation induced bending deformation of constrained segments and asymmetric charge density distribution on both anode and cathode sides of PUU films. Our results can provide new insight on design novel electroactive polyurethane elastomers.
Optical fingerprints of the electronic band reconstruction in van der Waals magnetic materials
Authors: Corasaniti M , Yang R , Liu Y , Petrovic C , Degiorgi L 
Published: December 2022

Abstract
We report a broadband study of the charge dynamics in the van der Waals magnetic materials 2H-M

x
TaS2 (M = Mn and Co), which span the onset of both long-range antiferromagnetic (AFM) and ferromagnetic (FM) order, depending on the intercalation M and its concentration x. We discover a spectral weight (SW) shift from high to low energy scales for FM compositions, while reversely SW is removed from low towards high spectral energies for AFM compounds. This maps the related reconstruction of the electronic band structure along the crossover from the FM to AFM order, which restores an occupation balance in the density of states between spin majority and minority bands of the intercalated 3d elements.
Microstructuring YbRh2Si2 for resistance and noise measurements down to ultra-low temperatures
Authors: Steppke Alexander , Hamann Sandra , König Markus , Mackenzie Andrew P , Kliemt Kristin , Krellner Cornelius , Kopp Marvin , Lonsky Martin , Müller Jens , Levitin Lev V , Saunders John , Brando Manuel 
Published: December 2022

Abstract
The discovery of superconductivity in the quantum critical Kondo-lattice system YbRh2Si2 at an extremely low temperature of 2 mK has inspired efforts to perform high-resolution electrical resistivity measurements down to this temperature range in highly conductive materials. Here we show that control over the sample geometry by microstructuring using focused-ion-beam techniques allows to reach ultra-low temperatures and increase signal-to-noise ratios (SNRs) tenfold, without adverse effects to sample quality. In five experiments we show four-terminal sensing resistance and magnetoresistance measurements which exhibit sharp phase transitions at the Néel temperature, and Shubnikov–de-Haas (SdH) oscillations between 13 T and 18 T where we identified a new SdH frequency of 0.39 kT. The increased SNR allowed resistance fluctuation (noise) spectroscopy that would not be possible for bulk crystals, and confirmed intrinsic

1

/

f

-type fluctuations. Under controlled strain, two thin microstructured samples exhibited a large increase of

T

N

from 67 mK up to 188 mK while still showing clear signatures of the phase transition and SdH oscillations. Superconducting quantum interference device-based thermal noise spectroscopy measurements in a nuclear demagnetization refrigerator down to 0.95 mK, show a sharp superconducting transition at

T

c

=
1.2

mK. These experiments demonstrate microstructuring as a powerful tool to investigate the resistance and the noise spectrum of highly conductive correlated metals over wide temperature ranges.
Optimal tests of genuine multipartite nonlocality
Authors: Pandit Mahasweta , Barasiński Artur , Márton István , Vértesi Tamás , Laskowski Wiesław 
Published: December 2022

Abstract
We propose an optimal and efficient numerical test for witnessing genuine multipartite nonlocality based on a geometric approach. In particular, we consider two non-equivalent models of local hidden variables, namely the Svetlichny and the no-signaling bilocal models. While our knowledge concerning these models is well established for Bell-type scenarios involving two measurement settings per party, the general case based on an arbitrary number of settings is a considerably more challenging task and very little work has been done in this field. In this paper, we applied such general tests to detect and characterize genuine n-way nonlocal correlations for various states of three qubits and qutrits. Apart from the fundamental problem of characterizing genuine multipartite nonlocal correlations, the extension of the number of measurements beyond two is also of practical importance. As a measure of nonlocality, we use the probability of violation of local realism under randomly sampled observables, and the strength of nonlocality, described by the resistance to white noise admixture. In particular, we analyze to what extent the Bell-type scenario involving two measurement settings can be used to certify genuine n-way nonlocal correlations generated for more general models. In addition, we propose a simple procedure to detect such nonlocal correlations for randomly chosen settings with an efficiency of up to 100%. Due to its near-perfect efficiency, our method may open new possibilities in device-independent quantum cryptography applications where strong nonlocality between all partners is required.
The effects of cavity diameter and material type of spatial confinement on intensity of laser-induced breakdown spectroscopy
Authors: Wang Yiqin , Jia Yueying , Gao Lu , Su Qi , Liu Wei , Zhou Tianchun , Xiao Qingmei 
Published: December 2022

Abstract
In this paper, we have investigated the spatial confinement effects on the spectrum intensity of tungsten plasma generated by laser-induced breakdown spectroscopy in the near-vacuum environment. The enhancement effects that vary with the diameters of the spatial confinement cylinders and with the material type are analyzed. We find that for an Al cylinder, the enhancement factor o reaches its highest value at diameter 4 mm. The primary causes behind this finding are attributed to the influences of diameter on the bounce time of shock wave propagating in the plasma as well as on the available range of spectrum collection. Moreover, the enhancement effect of Al cylinder is better than the other four types of materials: ZrO2, Al2O3, Fe and Cu. For each of the latter four types of materials, the thermal conductivity plays a major role on the enhancement effect, whereas for Al the enhancement effect is mainly due to its extremely large reflectivity. Particularly, for cavity with a diameter of 4 mm made of Aluminum, the maximum of the enhancement factor can approximately reach as high as 15. These experimental results indicate that the signal intensity of laser-induced breakdown spectroscopy can be dramatically improved by appropriately selecting diameter and material type of the cylindrical cavity.
Chirped soliton fission and fusion in dispersion oscillating fibers
Authors: Konyukhov A I , Mavrin P A 
Published: December 2022

Abstract
We found that pre-chirp of initial pulses allows to control both the fission and fusion of solitons in dispersion oscillating fiber characterized by a sinusoidally varying group velocity dispersion. The fission of second order solitons and collision of two co-propagated solitons are considered. It is shown that initial chirp can prevent the resonant fission of second order soliton into two pulses propagating with different group velocities. Inelastic collision of two in-phase solitons is found can be quite different, when the chirp imposed on initial pulses. The soliton transformation reflects in the set of output eigenvalues of the Zakharov–Shabat spectral problem. Manipulation of the input pulse chirp allows to control both real and imaginary parts of the eigenvalues at the output of the fiber.
Autonomic modulation by low-intensity focused ultrasound stimulation of the vagus nerve
Authors: Ji Ning , Li Yuanheng , Wei Jingjing , Chen Fei , Xu Lisheng , Li Guanglin , Lin Wan-Hua 
Published: December 2022

Abstract

Objective. Our previous study has shown that low-intensity focused ultrasound stimulation (FUS) of the vagus nerve could modulate blood pressure (BP), but its underlying mechanisms remain unclear. We hypothesized that low-intensity FUS of the vagus nerve would regulate autonomic function and thus BP. Approach. 17 anesthetized spontaneously hypertensive rats were treated with low-intensity FUS of the left vagus nerve for 15 min each trial. Continuous BP, heart rate, respiration rate (RR), and core body temperature were simultaneously recorded to evaluate the effects on BP and other physiological parameters. Heart rate variability (HRV), systolic BP variability, and baroreflex sensitivity were computed to evaluate the autonomic modulation function. A Control-sham group without stimulation and another Control-FUS group with non-target stimulation were also examined to exclude the influence of potential confounding factors on autonomic modulation. Main results. A prolonged significant decrease in BP, pulse pressure, RR, the normalized low-frequency power of HRV, and the low-to-high frequency power ratio of HRV were found after the low-intensity FUS of the left vagus nerve in comparison with the baseline and those of the control groups, demonstrating that activities of the sympathetic nervous system were inhibited. The prolonged significant increase of the normalized high-frequency power of HRV suggested the activation of parasympathetic activity. Significance. Low-intensity FUS of the left vagus nerve effectively improved the autonomic function by activating parasympathetic efferent and inhibiting sympathetic efferent, which contributes to BP reduction. The findings shed light on the hypotensive mechanism underlying FUS.