bluuebunny/crossref_metadata_2025 huggingface dataset:
Approaches to Treat Sensorineural Hearing Loss by Hair-Cell Regeneration: The Current State of Therapeutic Developments and Their Potential Impact on Audiological Clinical Practice
Authors: Hinton Ashley S. , Yang-Hood Aizhen , Schrader Angela D. , Loose Christopher , Ohlemiller Kevin K. , McLean Will J.
Published: May 2022

Abstract Sensorineural hearing loss (SNHL) is typically a permanent and often progressive condition that is commonly attributed to sensory cell loss. All vertebrates except mammals can regenerate lost sensory cells. Thus, SNHL is currently only treated with hearing aids or
cochlear implants. There has been extensive research to understand how regeneration occurs in nonmammals, how hair cells form during development, and what limits regeneration in maturing mammals. These studies motivated efforts to identify therapeutic interventions to regenerate hair cells
as a treatment for hearing loss, with a focus on targeting supporting cells to form new sensory hair cells. The approaches include gene therapy and small molecule delivery to the inner ear. At the time of this publication, early-stage clinical trials have been conducted to test targets that
have shown evidence of regenerating sensory hair cells in preclinical models. As these potential treatments move closer to a clinical reality, it will be important to understand which therapeutic option is most appropriate for a given population. It is also important to consider which audiological
tests should be administered to identify hearing improvement while considering the pharmacokinetics and mechanism of a given approach. Some impacts on audiological practice could include implementing less common audiological measures as standard procedure. As devices are not capable of repairing
the damaged underlying biology, hair-cell regeneration treatments could allow patients to benefit more from their devices, move from a cochlear implant candidate to a hearing aid candidate, or move a subject to not needing an assistive device. Here, we describe the background, current state,
and future implications of hair-cell regeneration research.
Resonances of plasma in stellarators contribute to energetic particle loss
Authors: Liebendorfer Adam
Published: May 2022

Comparing stellarator fusion reactor designs shows how some experimental devices struggle to contain fast particles.
A volume-of-fluid method for variable-density, two-phase flows at supercritical pressure
Authors: Poblador-Ibanez Jordi , Sirignano William A.
Published: May 2022

A two-phase, low-Mach-number flow solver is created and verified for variable-density liquid and gas with phase change. The interface is sharply captured using a split volume-of-fluid method generalized for a non-divergence-free liquid velocity and with mass exchange across the interface. Mass conservation to machine-error precision is achieved in the limit of incompressible liquid. This model is implemented for two-phase mixtures at supercritical pressure but subcritical temperature conditions for the liquid, as it is common in the early times of liquid hydrocarbon injection under real-engine conditions. The dissolution of the gas species into the liquid phase is enhanced, and vaporization or condensation can occur simultaneously at different interface locations. Greater numerical challenges appear compared to incompressible two-phase solvers that are successfully addressed for the first time: (a) local thermodynamic phase equilibrium and jump conditions determine the interface solution (e.g., temperature, composition, surface-tension coefficient); (b) a real-fluid thermodynamic model is considered; and (c) phase-wise values for certain variables (e.g., velocity) are obtained via extrapolation techniques. The increased numerical cost is alleviated with a split pressure-gradient technique to solve the pressure Poisson equation for the low-Mach-number flow. Thus, a fast Fourier transform method is implemented, directly solving the continuity constraint without an iterative process. Various verification tests show the accuracy and viability of the current approach. Then, the growth of surface instabilities in a binary system composed of liquid n-decane and gaseous oxygen at supercritical pressures for n-decane is analyzed. Other features of supercritical liquid injection are also shown.
High power high voltage bias-T for half wave resonators and radio frequency quadrupole couplers
Authors: Kaizer B. , Weissman L. , Perry A. , Zchut T. , Fishman I. , Rodnizki J. , Eizenshtat M. , Farber E.
Published: May 2022

High power high voltage bias-T units capable of delivering up to 100 kW CW RF power at 176 MHz and up to 4 kV DC were developed at the Soreq Nuclear Research Center for the Soreq Applied Research Accelerator Facility linac. Two separate bias-T units with different requirements were designed for the radio frequency quadrupole couplers and the half wave resonator couplers. The purpose of this bias-T is to prevent multipacting phenomena by application of a high voltage DC bias to inner conductors of RF couplers. Underlying design principles, indigenous development, and successful off-line and on-line tests results are presented.
Broadband microwave electrical transport spectroscopy for two-dimensional material systems
Authors: Levy Antonio L. , Zimmerman Neil M.
Published: May 2022

In recent years, interesting materials have emerged that are only available as μm-scale flakes and whose novel physics might be better understood through broadband microwave spectroscopy; examples include twisted bilayer graphene [Cao et al., Nature 556, 43 (2018)], 2D materials in which many-body phases are observed [Chen et al., Phys. Rev. Lett. 122, 026802 (2019)], and artificial lattices for analog quantum simulations [Salfi et al., Nat. Commun. 7, 1 (2016)]. Most previous techniques are unfortunately not sensitive for flakes below mm lateral sizes. We propose a simple technique that does not require sophisticated sample preparation nor Ohmic contact and show through theory and simulations that one will be able to qualitatively measure spectral features of interest and quantitatively measure the frequency-dependent complex conductivity.
Analysis of subharmonic and quasi-periodic vibrations of a Jeffcott rotor supported on a squeeze-film damper by the IHB method
Authors: Ri Kwangchol , Jang Junhyok , Yun Cholil , Pak Choljun , Kim Kwangchol
Published: May 2022

In rotors supported on a squeeze-film damper (SFD) with static eccentricity, subharmonic and quasi-periodic vibrations are generated by rotor unbalance. In this paper, subharmonic and quasi-periodic vibrations in a Jeffcott rotor supported on an SFD are analyzed using the modified incremental harmonic balance (IHB) method. Oil film forces in the damper are calculated using π film theory and short bearing approximation. These forces are first calculated in the time domain and then transformed into the frequency domain by Fourier transformation. The oil film forces in the frequency domain are multiplied by a transformation matrix to match the matrices used in the classical IHB method. To apply the continuation technique, the Jacobian matrix of residuals is calculated analytically. The stability analysis of the calculated solutions is analyzed using Floquet theory. Using this theory, saddle-node, symmetry breaking, period-doubling, and secondary Hopf bifurcations are detected. The phase plane, Poincaré sections, and time history at these bifurcation points are calculated using the Runge–Kutta method.
Vibration-induced detachment of droplets on superhydrophobic surfaces
Authors: Sun Kai , Shu Lingyun , Jia Feifei , Li Zhe , Wang Tianyou
Published: May 2022

Vibration is a robust and efficient method for droplet removal from superhydrophobic surfaces. In the present work, we experimentally investigated the dynamics of droplets on vibrating superhydrophobic surfaces, and established a mass-spring-damper theoretical model, to clarify the underlying physics of vibration-induced droplet detachment. Different droplet oscillation patterns were experimentally observed, namely, the droplet motion is in the same/opposite direction with the substrate when the vibration frequency is less/higher than the resonance frequency, respectively, and the transition occurs at the resonant frequency. The motion of the droplet is found to be composed of a transient response by the droplet free oscillation and a steady-state response by vibrating substrates. The critical condition for droplet detachment was identified to be the droplet energy (sum of the surface energy and kinetic energy) exceeds the surface adhesion energy. At the resonance frequency, the vibrational energy of the substrate is progressively accumulated in the droplet with the highest energy maintenance efficiency, and a small amplitude of vibration could therefore yield droplet detachment. The separation time shortens with the vibration amplitude and minimizes at the resonance frequency at a given amplitude. Our findings are helpful for the utilization of vibrating superhydrophobic surfaces for droplet removal.
Study of the thermal behavior of a battery pack with a serpentine channel
Authors: Ding Yuzhang , Ji Haocheng , Liu Rui , Jiang Yuwei , Wei Minxiang
Published: May 2022

To effectively enhance the thermal security of the Li-ion battery packs used in the electric vehicle industry, novel cooling systems equipped with serpentine channels are established. Then, the heat generation model is established and verified experimentally. In this research study, the structure of the cooling channel, the coolant velocity, the coolant temperature, and the coolant flow direction are considered to be the influencing factors. The results demonstrate that, by adopting the serpentine cooling channel, a better thermal conductivity can be obtained, and the type-B cooling system possesses a more reasonable structure. For different types of liquid cooling systems, the coolant temperature has a small influence on the temperature nephogram; however, for the same type of system, the coolant temperature strongly influences the temperature distribution. Similarly, the temperature difference is only related to the type of cooling system, with ∼6.09 and 5.53 K obtained for the type-A and type-B cooling systems, respectively. Furthermore, allowing the coolant in the serpentine cooling channels to flow in opposite directions can lower the value of the maximum temperature and temperature difference.
Effect of ellipticity of optical eigenwaves on the enhancement of efficiency of acousto-optic Bragg diffraction. A case of optically active Pb5Ge3O11 crystals
Authors: Mys Oksana , Kostyrko Myroslav , Adamenko Dmytro , Martynyuk-Lototska Iryna , Skab Ihor , Vlokh Rostyslav
Published: May 2022

We show that the existence of optical activity in an optical material can lead to essential enhancement of acousto-optic (AO) figure of merit. The reason is that the ellipticity of interacting optical eigenwaves approaches unity near the optical axis and so additional elasto-optic (EO) tensor components become involved in the effective EO coefficient. We demonstrate on lead germanate crystals that the increase in the efficiency of AO diffraction manifests itself for all types of AO interactions whenever the incident optical wave propagates close to the optical axis. In the particular case of diffraction in the interaction plane XZ of Pb5Ge3O11 crystals, the maximal enhancement of the AO figure of merit takes place under conditions of the isotropic diffraction of ordinary and extraordinary optical waves with a pure transverse acoustic wave (AW) polarized parallel to the Y axis (a so-called AW PT2), with the AO figure of merit increasing from zero to 7.5 × 10−17 s3/kg, and the types of anisotropic diffraction on the AWs QT1 and PT2 when the AO figure of merit increases twice (e.g., from 7.6 × 10−17 to 1.5 × 10−16 s3/kg). The maximal AO efficiency in the interaction plane XZ is reached at types I and II of the isotropic AO interactions of ordinary and extraordinary optical waves with a quasi-longitudinal AW; in these cases, the AO figure of merit increases from 6.8 × 10−15 to 12.4 × 10−15 s3/kg and from 5.6 × 10−15 to 12.4 × 10−15 s3/kg, respectively.
Anti-phase oscillations of an elliptical cavitation vortex in Francis turbine draft tube
Authors: Favrel Arthur , Liu Zhihao , Khozaei Mohammad Hossein , Irie Tatsuya , Miyagawa Kazuyoshi
Published: May 2022

In this paper, the dynamic behavior of a precessing cavitation vortex featuring an elliptical cross section in Francis turbine draft tube is investigated. This phenomenon may occur for values of discharge coefficient within 70%–85% of the discharge coefficient at the best efficiency point, for which Francis turbines can experience the onset of the so-called upper-part load (UPL) instability. The latter is characterized by the propagation of high-amplitude synchronous pressure fluctuations through the complete hydraulic circuit. High-speed visualizations of the cavitation vortex are performed on a Francis turbine model by means of two cameras synchronized with pressure sensors arranged along the draft tube for different Thoma numbers at a given discharge coefficient. A simplified analytical model of the cavitation vortex is proposed. It enables the interpretation of the video post-processing results in the frequency domain and the estimation of both the vortex cross section dimensions and their oscillations with time. It is first demonstrated that both the vortex cross section ellipticity (given by the ratio between its semi-major and semi-minor axes) and the amplitude of its oscillations are directly correlated with the amplitude of UPL pressure fluctuations during intermittent UPL instability. Furthermore, the evolution along the draft tube of the dimensions of the elliptical vortex cross section and their oscillations during fully developed UPL instability is highlighted. The ellipticity of the vortex cross section increases as the vortex center position gets closer to the draft tube wall away from the turbine outlet. In addition, the vortex cross section dimensions oscillate with opposite phase from either side of a pressure node located along the draft tube. This results in low oscillations of the total void fraction in the draft tube, compared with results obtained locally. This effect should be considered in the one-dimensional modeling of the cavitation flow during UPL instability for further stability analysis. The new insights on UPL instability presented in this paper may potentially lead to a better theoretical understanding and modeling of this phenomenon in Francis turbines draft tube.
Structure-based model of fucoxanthin–chlorophyll protein complex: Calculations of chlorophyll electronic couplings
Authors: Mikalčiūtė Austėja , Gelzinis Andrius , Mačernis Mindaugas , Büchel Claudia , Robert Bruno , Valkunas Leonas , Chmeliov Jevgenij
Published: May 2022

Diatoms are a group of marine algae that are responsible for a significant part of global oxygen production. Adapted to life in an aqueous environment dominated by the blue–green light, their major light-harvesting antennae—fucoxanthin–chlorophyll protein complexes (FCPs)—exhibit different pigment compositions than of plants. Despite extensive experimental studies, until recently the theoretical description of excitation energy dynamics in these complexes was limited by the lack of high-resolution structural data. In this work, we use the recently resolved crystallographic information of the FCP complex from Phaeodactylum tricornutum diatom [Wang et al., Science 363, 6427 (2019)] and quantum chemistry-based calculations to evaluate the chlorophyll transition dipole moments, atomic transition charges from electrostatic potential, and the inter-chlorophyll couplings in this complex. The obtained structure-based excitonic couplings form the foundation for any modeling of stationary or time-resolved spectroscopic data. We also calculate the inter-pigment Förster energy transfer rates and identify two quickly equilibrating chlorophyll clusters.
How electronic superpositions drive nuclear motion following the creation of a localized hole in the glycine radical cation
Authors: Danilov Don , Tran Thierry , Bearpark Michael J. , Marangos Jon P. , Worth Graham A. , Robb Michael A.
Published: May 2022

In this work, we have studied the nuclear and electron dynamics in the glycine cation starting from localized hole states using the quantum Ehrenfest method. The nuclear dynamics is controlled both by the initial gradient and by the instantaneous gradient that results from the oscillatory electron dynamics (charge migration). We have used the Fourier transform (FT) of the spin densities to identify the “normal modes” of the electron dynamics. We observe an isomorphic relationship between the electron dynamics normal modes and the nuclear dynamics, seen in the vibrational normal modes. The FT spectra obtained this way show bands that are characteristic of the energy differences between the adiabatic hole states. These bands contain individual peaks that are in one-to-one correspondence with atom pair (+·) ↔ (·+) resonances, which, in turn, stimulate nuclear motion involving the atom pair. With such understanding, we anticipate “designer” coherent superpositions that can drive nuclear motion in a particular direction.
Digitalisation and automation for the development of modern engineering workflows
Authors: Hernandez Alan , Sinclair Michael
Published: May 2022

Automation, as part of the Energy Industry’s Digital Transformation, is producing significant time savings in modern engineering workflows whilst minimising opportunity for human error. A challenge we face is ensuring these automated workflows are accessible to people in the industry without programming experience. Xodus’ solution to this problem is FLUX. FLUX works as an object-oriented, ‘no-code’, web-based platform which tracks, stores and executes both technical and non-technical workflows. Workflows are first automated in-house by developing scripts, which are then hosted on FLUX allowing them to be easily shared across the business without requiring programming knowledge. A popular use case for FLUX is in the concept engineering phase of a project when performing parametric analyses. Multiple simulation cases (typically thousands) assessing all the different possible combinations of design parameters can be interrogated at once. FLUX can then automatically output an interactive parallel coordinate plot to highlight the impact of each parameter on the overall system. Platforms such as FLUX are an effective solution to increasing accessibility to automation for the industry via ‘no-code’ mechanisms, the ability to interface through an intuitive digital platform where project data is stored, exchanged and analysed through automated calculations is a step forward in engineering workflow efficiency.
QTL detection for grain yield and micro-nutrition contents in rice (
Authors: Duan Liuying , Wu Ting , Li Xia , Huang Derun , Li Xiaobai , Wen Xixian , Chen Ping , Xie Jiankun , Hu Biaolin
Published: May 2022

Context Enhancing grain yield and micro-nutrition contents in rice (Oryza sativa L.) through biofortification breeding is an efficient way to address micro-nutrient deficiencies in human. Aims QTL mapping for grain yield and micro-nutritional traits is prerequisite for developing new rice varieties. Methods QTLs for grain yield and micro-nutritional traits were identified using a backcross inbred lines (BIL) derived from an interspecific backcross of Xieqingzao B and Dongxiang wild rice (Oryza rufipogon Griff.). Key results A total of 16 and 29 QTLs were identified for grain Zn, Mn and Cu contents, including three for brown and milled rice, 10 for brown rice only, and three for milled rice only, and for grain related traits, respectively. Among grain micro-nutrient QTLs, three QTLs, qMn4, qMn6.2 and qZn6.2, showed genetic effects on both brown and milled rice. Conclusion Sixteen QTLs for grain related traits and eight QTLs for grain micro-nutrient content had O. rufipogon favourable alleles. A total 31 QTLs were clustered eight chromosomal regions. Importantly, two clusters, qZn4/qGW4 and qZn6.2/qMn6.2/qCu6.3/qGYP6.2, had the favourable wild alleles, suggesting that O. rufipogon alleles had synergistic effects on both yield component and micro-nutrient content. Implications These candidate QTLs could be useful for the improvement of grain yield and micro-nutrients through QTL pyramiding.
Rapid deployment of support for a mental health crisis: 10 priorities framing Australia’s COVID-19 pandemic response
Authors: Desborough Jane , Blashki Grant , Hall Dykgraaf Sally , Vine Ruth , Roddam Mark , Munindradasa Ashvini , Kidd Michael
Published: May 2022

The COVID-19 pandemic has challenged the mental health of communities worldwide, with the triple pressures of financial insecurity, lockdowns, and worry about the infection. Australia rapidly deployed resources to protect the mental wellbeing of the community through supplementing existing services, supporting at-risk groups, investing in social supports, embracing technology, and supporting the health workforce. This paper describes the Australian Government’s investment in mental health during the COVID-19 pandemic in relation to the 10 priority areas identified in Australia’s National Mental Health Pandemic Response Plan.
Intermediate-state imaging of electrical switching and quantum coupling of molybdenum disulfide monolayer
Authors: Wang Zixiao , Niu Ben , Jiang Bo , Chen Hong-Yuan , Wang Hui
Published: May 2022

Significance

Thin transparent semiconductors of two-dimensional materials are attractive for the practical applications in next-generation nanoelectronic and optoelectronic devices. Probing the electron states and electrical switching mechanisms of a molybdenum disulphide monolayer with atomic-scale thickness (6.5 Å) allows us to unlock the full technological potential of this nanomaterial. We introduced a plasmonic phase imaging method to uncover the underlying mechanism and detailed switching dynamics of an electrical-state switching event. This dramatic phase change can be attributed to the reversible switching of classical electromagnetic coupling and quantum coupling effects interplaying between a single metal nanoparticle and molybdenum disulphide monolayer, and the transient intermediate states during the switching event can be directly imaged by a plasmonic technique.
The causal effect of a family planning intervention on women’s contraceptive use and birth spacing
Authors: Karra Mahesh , Maggio Dan , Guo Muqi , Ngwira Bagrey , Canning David
Published: May 2022

Significance

Improving access to family planning may promote contraceptive use after childbirth and reduce the likelihood of closely spaced high-risk births; however, empirical evidence for these claims is limited. We present findings from a field experiment that examines the causal impact of a broad-based family-planning intervention on postpartum contraceptive use and fertility over a 2-y period, which allows us to assess impact on high-risk short pregnancy intervals. Our findings demonstrate that the benefits of family planning extend beyond contraceptive use to improve fertility and healthy birth spacing. Evidence from this study will contribute to the design of effective family-planning programs and to informing the ongoing policy debate about how such programs impact longer-term health and development more broadly.
A peptide-mediated, multilateral molecular dialogue for the coordination of pollen wall formation
Authors: Truskina Jekaterina , Brück Stefanie , Stintzi Annick , Boeuf Sophy , Doll Nicolas M. , Fujita Satoshi , Geldner Niko , Schaller Andreas , Ingram Gwyneth C.
Published: May 2022

Significance

Pollen viability depends on a tough external barrier called the pollen wall. Pollen wall components are produced by tapetum cells, which surround developing pollen grains within the anther. Precise coordination of tapetum activity with pollen grain development is required to ensure effective pollen wall formation. Here, we reveal that this is achieved through a multidirectional dialogue involving three distinct cell types. We show that peptide precursors from the tapetum are activated by proteases produced stage specifically in developing pollen grains. Unexpectedly, we found that activated peptides are perceived not in the tapetum, but in the middle layer, which encloses the developing tapetum and pollen grains, revealing an unsuspected role for this enigmatic cell layer in the control of tapetum development.
Single-cell transcriptomic classification of rabies-infected cortical neurons
Authors: Patiño Maribel , Lagos Will N. , Patne Neelakshi S. , Tasic Bosiljka , Zeng Hongkui , Callaway Edward M.
Published: May 2022

Significance

Monosynaptic rabies tracing using glycoprotein (G)-deleted rabies virus is widely applied to study cortical circuit connectivity. However, connectivity tracing using rabies virus could benefit from higher throughput methods of assigning rabies-labeled inputs to neuronal cell types and the ability to assign cells to finer genetically defined subtypes. Using single-nucleus RNA sequencing, we demonstrate that rabies-infected cortical neurons can be transcriptomically characterized according to established cell types when using transcriptome-wide analysis. Furthermore, we find that rabies infection differentially affects distinct host genes, suggesting that some genes may be more vulnerable to transcriptional modulation than others, which may impede the classification of rabies-infected cells when using methods that rely on the detection of single or few genes.
Sensing ultrashort electronic coherent beating at conical intersections by single-electron pulses
Authors: Asban Shahaf , Keefer Daniel , Chernyak Vladimir Y. , Mukamel Shaul
Published: May 2022

Significance

In a theoretical study, we present an ultrafast technique for probing time-dependent molecular charge densities. An ultrafast optical pump first brings the molecule into an electronic nonstationary state. This is followed by coherent inelastic scattering of a broadband single-electron probe pulse with a variable delay
T
, which is detected spectrally. The technique is applied to reveal phase-sensitive background-free coherent electron beating in the conical intersection passage in uracil and reveals the otherwise elusive coherent beating of strongly coupled electrons and nuclei.
Attribution in novice academic writing
Authors: Hasselgård Hilde
Published: May 2022

Academic attribution, the direct acknowledgement of external sources, is investigated in two corpora of novice
academic English, representing first and second language writing in linguistics. The forms and uses of attribution are analysed in
a formal-functional framework. There is an overall underrepresentation of attribution in the learner corpus. However, the corpora
have a similar proportional distribution of integral and non-integral attribution, but a difference in subtypes of these. Undated
attributions are discussed as a special case. They occur in specific contexts, of which reference to course reading is peculiar to
novice writing. Comparisons with expert corpora in Norwegian and English indicate that some, but not all, of the differences
between the novice corpora may be linked to influence from the learners’ first language and culture.
The heart of the matter: A matter of the heart
Authors: Kövecses Zoltán
Published: May 2022

Why should Jesus die? I attempt to investigate the symbolic roots and significance of the crucifixion by means of the conceptual tools and methodology of cognitive semantics. In particular, I propose that we approach the meaning of Jesus’ death on four symbolic levels:

the level where Jesus is a sacrificial lamb;

the level where Jesus is a scapegoat and a sufferer for people’s sins;

the level where Jesus is a redeemer and a savior;

the level where Jesus is bread and wine in the Holy Communion.

I suggest that all four levels prove distinct yet interdependent interpretations for the crucifixion. The different interpretations bring to the fore different aspects of the figure of Jesus and his death. While all of these aspects have been studied extensively by various authors from a cognitive linguistic perspective, my focus will be on the interrelations and interdependence of the four interpretations of Jesus’ figure and death.
Attribute transfer
Authors: Panther Klaus-Uwe
Published: May 2022

The rhetorical tropehypallage, here calledAttribute Transfer(AT), has been exploited artistically and creatively since antiquity in poetic and narrative discourse, but it is also used in ordinary language. This study focuses on modifier-noun constructions in which the prenominal modifier (attribute) is “shifted” from one position to another – a “transfer” that triggers metonymic interpretations. AT constitutes a violation of the iconically motivated proximity principle (Givón 2001) according to which the conceptual and functional closeness of linguistic units is mirrored in their morphosyntactic structure. The principle of proximity competes with metonymic motivation – the latter prevailing at the expense of the former. An interesting structural parallelism exists between AT and the shift of the negatornotfrom its “logical” position to another syntactic slot (‘neg-transportation’), which again exhibits a violation of the proximity principle. The article concludes with some suggestions for further research, especially cross-linguistic and typological investigations.
Vacuum Einstein field equations in smooth metric measure spaces: the isotropic case*
Authors: Brozos-Vázquez M , Mojón-Álvarez D
Published: May 2022

On a smooth metric measure spacetime (M, g, e
−f
dvol

g
), we define a weighted Einstein tensor. It is given in terms of the Bakry–Émery Ricci tensor as a tensor which is symmetric, divergence-free, concomitant of the metric and the density function. We consider the associated vacuum weighted Einstein field equations and show that isotropic solutions have nilpotent Ricci operator. Moreover, the underlying manifold is a Brinkmann wave if it is two-step nilpotent and a Kundt spacetime if it is three-step nilpotent. More specific results are obtained in dimension 3, where all isotropic solutions are given in local coordinates as plane waves or Kundt spacetimes.
Multipole oscillator strength and polarizability for confined hydrogen-like atoms under high pressure
Authors: Mukherjee Neetik , Chakraborty Sudipta , Roy Amlan K
Published: May 2022

Multipole oscillator strength (f
(k)) acts as a foundation in estimating multipole polarizability

(

α

i

(

k

)

)

in a quantum system. Moreover, a knowledge of f
(k) as well as

α

i

(

k

)

under extreme pressure may be treated as the benchmark in high pressure spectroscopy. Further, an investigation of rate of change of these quantities and transition moment integral as a function of confinement radius (R) may offer many hitherto unexplained features. Here, we derive several such relations for confined H-like atom as a test case. In this regard, a virial theorem is utilized. The versatility of these derived relations in the context of atom is also discussed. Apart from that, we report numerically calculated results of α
(k), f
(k) for a confined H-like atom trapped inside a spherical cavity of radius R. A detailed and systematic analysis of these are undertaken in case of k ranging from 1–4, with special emphasis on 1s, 2s, 2p, 3d states. Their behavior is found to be significantly different from their respective free counterparts.
Field orientation dependent magnetization reversal and dynamics in sub-100 nm wide permalloy nanowires
Authors: Kuchibhotla Mahathi , Talapatra Abhishek , Haldar Arabinda , Adeyeye Adekunle Olusola
Published: May 2022

We have investigated the magnetization reversal mechanism and dynamic behaviour of 90 nm wide permalloy nanowires patterned over a large area as a function of thickness (t) in the range from 20 nm to 70 nm and applied field orientation. The reversal processes and dynamic properties are probed using the magneto-optical Kerr effect and broadband ferromagnetic resonance (FMR) spectroscopy respectively. We have observed that both the static and dynamic properties are markedly sensitive to the film thickness. For t= 20 nm, the magnetization reversal process is dominated by coherent rotation mode due to the strong shape anisotropy and the onset of curling mode is observed. The FMR spectra display the existence of two well-separated modes, unlike the single mode which existed in the large width nanowires of the same thickness. The two modes at high and low frequencies correspond to the excitations at the centre and edges of the wire respectively. For t ⩾ 50 nm, the magnetization reversal process is dominated by curling mode of reversal. The centre mode frequency is found to be sensitive to the film thickness and shows two fold anisotropy. The experimental results are substantiated with micromagnetic simulations. These results have potential implications in designing reconfigurable magnonic crystals for microwave devices.
Cerium metal oxidation studied by IR reflection-absorption and Raman scattering spectroscopies
Authors: Schweke Danielle , Rubin Alon , Rabinovitch Lior , Kraynis Olga , Livneh Tsachi
Published: May 2022

Oxidation of cerium metal is a complex process which is strongly affected by the presence of water vapor in the oxidative atmosphere. Here, we explore, by means of infrared reflection-absorption spectroscopy (IRRAS) and Raman scattering spectroscopies, thin oxide films, formed on cerium metal during oxidation, under dry vs ambient (humid) air conditions (∼0.2% and ∼50% relative humidities, respectively) and compare them with a thin film of CeO2 deposited on a Si substrate. Complementary analysis of the thin films using x-ray diffraction and focused ion beam-scanning electron microscopy enables the correlation between their structure and spectroscopic characterizations. The initial oxidation of cerium metal results in the formation of highly sub-stoichiometric CeO2−x
. Under dry air conditions, a major fraction of that oxide reacts with oxygen to form CeO∼2, which is spectroscopically detected by Raman scattering F
2g
symmetry mode and by IRAAS F
1u
symmetry mode, splitted into doubly-degenerate transverse optic and mono-degenerate longitudinally optic (LO) modes. In contrast, under ambient (humid) conditions, the oxide formed is more heterogenous, as the reaction of CeO2−x
diverges towards the dominant formation of Ce(OH)3. Prior to the spectral emergence of Ce(OH)3, hydrogen ions incorporate into the highly sub-stoichiometric oxide, as manifested by Ce–H local vibrational mode detected in the Raman spectrum. The spectroscopic response of the thin oxide layer thus formed is more complex; particularly noted is the absence of the LO mode. It is attributed to the high density of microstructural and compositional defects in the oxide layer, which results in a heterogenous dielectric nature of the thin film, far from being representable by a single phase of CeO∼2.
Simultaneous measurement of phase retardation and fast axis azimuth of wave plate based on equivalent component and phase detection
Authors: Chen Qianghua , Ding Jinhong , Guan Yu , Han Wenyuan , Zhou Sheng , He Yongxi , Wang Feng
Published: May 2022

Wave plates (WPs) are key components in optical polarization systems whose phase retardations and fast axis azimuths should be determined accurately. At present many measurement methods are based on light intensity detection which is inevitably affected by light intensity fluctuations so that the measurement accuracy is limited. What’s more, quite a few methods cannot measure WPs’ fast axis azimuths simultaneously. In this paper a method of simultaneously measuring the phase retardation and fast axis azimuth of arbitrary WP is proposed, which is based on equivalent component and phase detection. A rotatable half wave plate (HWP) and a retroreflector are used and its effect is equivalent to measuring an equivalent WP whose phase retardation is twice that of the measured wave plate, which is equivalent to doubling the measurement resolution. Phase detection is used to process the signals which means the measurement accuracy is better than that by usual light intensity detection. What’s more, the presented method eliminates the angle positioning errors of birefringent components in principle which exists in many present WP measurement methods. Finally, the measurement system setup is simple as well as the measurement process. The measurement formulae are deduced and corresponding WP measuring system is established. The error analysis shows that the system measurement uncertainty is about 3.9′ for the phase retardation and 5” for the fast axis azimuth. Experiment results and comparisons of quarter WPs and HWPs show that the presented method is in good agreement with other method. The phase retardation measurement repeatability is also good with a standard deviation about 2′.
Atomistic simulation of martensite decay
Authors: Oila Adrian
Published: May 2022

Molecular dynamics simulations were used to study the phenomenon of martensite decay in gears by deforming a grinding mark subjected to contact stresses exerted by a rigid plate. The velocities imposed on the rigid plate and the interatomic potential chosen to represent the interactions between the rigid plate and the grinding mark allow for a realistic representation of an elastohydrodynamic contact with an average friction coefficient of 0.05 and all values below 0.1. Due to the initial plastic deformation the height of the grinding mark reduces significantly between two loading cycles, consequently, during the second loading cycle the deformation is predominantly elastic and dislocations only nucleate during the first loading cycle. The diffusion of carbon atoms from the grinding mark leads to the formation of plate-like regions depleted in carbon and precipitation of cementite, the products of martensite decay, as observed experimentally.
Advances in heterostructured scintillators: toward a new generation of detectors for TOF-PET
Authors: Pagano Fiammetta , Kratochwil Nicolaus , Salomoni Matteo , Pizzichemi Marco , Paganoni Marco , Auffray Etiennette
Published: May 2022

Objective. Time-of-flight-positron emission tomography would highly benefit from a coincidence time resolution (CTR) below 100 ps: improvement in image quality and patient workflow, and reduction of delivered dose are among them. This achievement proved to be quite challenging, and many approaches have been proposed and are being investigated for this scope. One of the most recent consists in combining different materials with complementary properties (e.g. high stopping power for 511 keV

γ

-ray and fast timing) in a so-called heterostructure, metascintillator or metapixel. By exploiting a mechanism of energy sharing between the two materials, it is possible to obtain a fraction of fast events which significantly improves the overall time resolution of the system. Approach. In this work, we present the progress on this innovative technology. After a simulation study using the Geant4 toolkit, aimed at understanding the optimal configuration in terms of energy sharing, we assembled four heterostructures with alternating plates of BGO and EJ232 plastic scintillator. We fabricated heterostructures of two different sizes (3 × 3 × 3 mm3 and  3 × 3 × 15 mm3), each made up of plates with two different thicknesses of plastic plates. We compared the timing of these pixels with a standard bulk BGO crystal and a structure made of only BGO plates (layered BGO). Main results. CTR values of 239 ± 12 ps and 197 ± 10 ps FWHM were obtained for the 15 mm long heterostructures with 100 µm and 200 µm thick EJ232 plates (both with 100 µm thick BGO plates), compared to 271 ± 14 ps and 303 ± 15 ps CTR for bulk and layered BGO, respectively. Significance. Significant improvements in timing compared to standard bulk BGO were obtained for all the configurations tested. Moreover, for the long pixels, depth of interaction (DOI) collimated measurements were also performed, allowing to validate a simple model describing light transport inside the heterostructure.
Reduction of transport due to magnetic shear in gyrokinetic simulations of the scrape-off layer
Authors: Mandell N R , Hammett G W , Hakim A , Francisquez M
Published: May 2022

The effect of varying magnetic shear on scrape-off layer turbulence and profiles is studied via electromagnetic gyrokinetic simulations of a helical scrape-off layer model. We develop a model helical geometry with magnetic shear and a corresponding field-aligned coordinate system, which is used for simulations with theGkeyllcode. We find that perpendicular transport is reduced in cases with stronger shear, resulting in higher peak particle and heat fluxes to the endplates. Electromagnetic effects slightly increase transport in strong shear cases.
Vacuum decay in the Lorentzian path integral
Authors: Hayashi Takumi , Kamada Kohei , Oshita Naritaka , Yokoyama Jun'ichi
Published: May 2022

We apply the Lorentzian path integral to the decay of a false vacuum and estimate the false-vacuum decay rate. To make the Lorentzian path integral convergent, the deformation of an integration contour is performed by following the Picard-Lefschetz theory. We show that the nucleation rate of a critical bubble, for which the corresponding bounce action is extremized, has the same exponent as the Euclidean approach. We also extend our computation to the nucleation of a bubble larger or smaller than the critical one to which the Euclidean formalism is not applicable.
An improved high stability and low distortion phase generated carrier demodulation algorithm for phase-sensitive optical time-domain reflectometers
Authors: Xiao Wenzhe , Cheng Jing , Zhang Dawei , Kong Yong , Ye Hualong , He Jun
Published: May 2022

The phase generated carrier (PGC) demodulation technique for phase-sensitive optical time-domain reflectometry (Ф-OTDR) has significant potential in applications involving distributed optical fiber sensing and imaging. An improved PGC demodulation algorithm for a Ф-OTDR combined with an unbalanced Michelson interferometer system is presented in this letter. This modified PGC technique uses the one output signal as a fundamental carrier frequency signal with mathematical transformations, and another output is the modulated signal, which enable the two signals to be output synchronously from the interferometer. Theoretical simulations and experiments demonstrate that the linear and nonlinear distortion caused by phase modulation depth and carrier phase delay are well suppressed by the proposed algorithm with high stability and low distortion. The signal-to-noise-and-distortion ratio of sensors using the proposed method in the same conditions achieve gains of 12.98 dB, 30.82 dB and 6.93 dB over PGC-Arctan, PGC-differential-and-cross-multiplying and PGC-single-path differential division method, respectively. Experimental verification shows that the proposed demodulation system can exactly recover the original signals of multiple vibration positions simultaneously, and the system employing the ameliorated PGC demodulation algorithm has the noise level of about 1.83 × 10−4 rad (√Hz)−1 and a large dynamic range of 65.72 dB @ 800 Hz, which provides a new choice for distributed optical fiber sensing technology.
Steady-state and transient electronic transport properties of β-(Al
x
Ga1–x
)2O3/Ga2O3 heterostructures: An ensemble Monte Carlo simulation
Authors: Liu Yan , Wang Ping , Yang Ting , Wu Qian , Yang Yintang , Zhang Zhiyong
Published: May 2022

The steady-state and transient electron transport properties of β-(Al
x
Ga1−x
)2O3/Ga2O3 heterostructures were investigated by Monte Carlo simulation with the classic three-valley model. In particular, the electronic band structures were acquired by first-principles calculations, which could provide precise parameters for calculating the transport properties of the two-dimensional electron gas (2DEG), and the quantization effect was considered in the Γ valley with the five lowest subbands. Wave functions and energy eigenvalues were obtained by iteration of the Schrödinger–Poisson equations to calculate the 2DEG scattering rates with five main scattering mechanisms considered. The simulated low-field electron mobilities agree well with the experimental results, thus confirming the effectiveness of our models. The results show that the room temperature electron mobility of the β-(Al0.188Ga0.812)2O3/Ga2O3 heterostructure at 10 kV⋅cm−1 is approximately 153.669 cm2⋅V−1⋅s−1, and polar optical phonon scattering would have a significant impact on the mobility properties at this time. The region of negative differential mobility, overshoot of the transient electron velocity and negative diffusion coefficients are also observed when the electric field increases to the corresponding threshold value or even exceeds it. This work offers significant parameters for the β-(Al
x
Ga1−x
)2O3/Ga2O3 heterostructure that may benefit the design of high-performance β-(Al
x
Ga1−x
)2O3/Ga2O3 heterostructure-based devices.
Anti-symmetric sampled grating quantum cascade laser for mode selection
Authors: Guo Qiangqiang , Zhang Jinchuan , Cheng Fengmin , Zhuo Ning , Zhai Shenqiang , Liu Junqi , Wang Lijun , Liu Shuman , Liu Fengqi
Published: May 2022

For mode selection in a quantum cascade laser (QCL), we demonstrate an anti-symmetric sampled grating (ASG). The wavelength of the –1-th mode of this laser has been blue-shifted more than 75 nm (∼ 10 cm−1) compared with that of an ordinary sampled grating laser with an emission wavelength of approximately 8.6 μm, when the periodicities within both the base grating and the sample grating are kept constant. Under this condition, an improvement in the continuous tuning capability of the QCL array is ensured. The ASG structure is fabricated in holographic exposure and optical photolithography, thereby enhancing its flexibility, repeatability, and cost-effectiveness. The wavelength modulation capability of the two channels of the grating is insensitive to the variations in channel size, assuming that the overall waveguide width remains constant. The output wavelength can be tailored freely within a certain range by adjusting the width of the ridge and the material of the cladding layer.
Device simulation of quasi-two-dimensional perovskite/silicon tandem solar cells towards 30%-efficiency
Authors: Xie Xiao-Ping , Bai Qian-Yu , Liu Gang , Dong Peng , Liu Da-Wei , Ni Yu-Feng , Liu Chen-Bo , Xi He , Zhu Wei-Dong , Chen Da-Zheng , Zhang Chun-Fu
Published: May 2022

Perovskite/silicon (Si) tandem solar cells have been recognized as the next-generation photovoltaic technology with efficiency over 30% and low cost. However, the intrinsic instability of traditional three-dimensional (3D) hybrid perovskite seriously hinders the lifetimes of tandem devices. In this work, the quasi-two-dimensional (2D) (BA)2(MA)
n – 1Pb
n
I3n + 1 (n = 1, 2, 3, 4, 5) (where MA denotes methylammonium and BA represents butylammonium), with senior stability and wider bandgap, are first used as an absorber of semitransparent top perovskite solar cells (PSCs) to construct a four-terminal (4T) tandem devices with a bottom Si-heterojunction cell. The device model is established by Silvaco Atlas based on experimental parameters. Simulation results show that in the optimized tandem device, the top cell (n = 4) obtains a power conversion efficiency (PCE) of 17.39% and the Si bottom cell shows a PCE of 11.44%, thus an overall PCE of 28.83%. Furthermore, by introducing a 90-nm lithium fluoride (LiF) anti-reflection layer to reduce the surface reflection loss, the current density (J
sc) of the top cell is enhanced from 15.56 mA/cm2 to 17.09 mA/cm2, the corresponding PCE reaches 19.05%, and the tandem PCE increases to 30.58%. Simultaneously, in the cases of n = 3, 4, and 5, all the tandem PCEs exceed the limiting theoretical efficiency of Si cells. Therefore, the 4T quasi-2D perovskite/Si devices provide a more cost-effective tandem strategy and long-term stability solutions.