bluuebunny/crossref_metadata_2025 huggingface dataset:
Intelligent meta-imagers: From compressed to learned sensing
Authors: Saigre-Tardif Chloé , Faqiri Rashid , Zhao Hanting , Li Lianlin , del Hougne Philipp
Published: March 2022

Computational meta-imagers synergize metamaterial hardware with advanced signal processing approaches such as compressed sensing. Recent advances in artificial intelligence (AI) are gradually reshaping the landscape of meta-imaging. Most recent works use AI for data analysis, but some also use it to program the physical meta-hardware. The role of “intelligence” in the measurement process and its implications for critical metrics like latency are often not immediately clear. Here, we comprehensively review the evolution of computational meta-imaging from the earliest frequency-diverse compressive systems to modern programmable intelligent meta-imagers. We introduce a clear taxonomy in terms of the flow of task-relevant information that has direct links to information theory: compressive meta-imagers indiscriminately acquire all scene information in a task-agnostic measurement process that aims at a near-isometric embedding; intelligent meta-imagers highlight task-relevant information in a task-aware measurement process that is purposefully non-isometric. The measurement process of intelligent meta-imagers is, thus, simultaneously an analog wave processor that implements a first task-specific inference step “over-the-air.” We provide explicit design tutorials for the integration of programmable meta-atoms as trainable physical weights into an intelligent end-to-end sensing pipeline. This merging of the physical world of metamaterial engineering and the digital world of AI enables the remarkable latency gains of intelligent meta-imagers. We further outline emerging opportunities for cognitive meta-imagers with reverberation-enhanced resolution, and we point out how the meta-imaging community can reap recent advances in the vibrant field of metamaterial wave processors to reach the holy grail of low-energy ultra-fast all-analog intelligent meta-sensors.
Homointerface planar Josephson junction based on inverse proximity effect
Authors: Fan Juewen , Jiang Bingyan , Zhao Jiaji , Bi Ran , Zhou Jiadong , Liu Zheng , Kang Ning , Qu Fanming , Lu Li , Wu Xiaosong
Published: March 2022

The quality of a superconductor–normal metal–superconductor Josephson junction (JJ) depends crucially on the transparency of the superconductor–normal metal (S/N) interface. We demonstrate a technique for fabricating planar JJs with perfect S/N interfaces. The technique utilizes a strong inverse proximity effect discovered in Al/V5S8 bilayers, by which the Al layer is driven into the resistive state. The highly transparent S/N homointerface and the peculiar normal metal enable the flow of Josephson supercurrent across a 2.9 μm long weak link. Moreover, our JJ exhibits a giant critical current and a large product of the critical current and the normal state resistance.
Vanishing flux perturbation, pressure, and magnetic field limit in a Chaplygin magnetogasdynamics
Authors: Nie Yongsheng , Hao Jin , Yang Hanchun
Published: March 2022

The Riemann problem for a Chaplygin magnetogasdynamics system of compressible fluid flow with a triple parameter perturbation containing flux, pressure, and magnetic field is first solved. Second, it is shown that as the triple parameter flux perturbation, pressure, and magnetic field vanish, any Riemann solution containing two shock waves tends to a delta-shock solution to the transport equations and any Riemann solution containing two rarefaction waves tends to a vacuum solution to the transport equations. Third, it is also proved that as the double parameter flux perturbation and magnetic field vanish, any Riemann solution containing two shock waves approaches a delta-shock solution to the Chaplygin gas equations and any Riemann solution containing two rarefaction waves tends to a solution containing two contact discontinuities of the Chaplygin gas equations. Finally, some numerical results are presented to be consistent with the theoretical analysis.
A comprehensive investigation of vortex-induced vibrations and flow-induced rotation of an elliptic cylinder
Authors: Shahzer Mohammad Abu , Khan Mohammad Athar , Anwer Syed Fahad , Khan Saleem Anwar , Khan Mohammad Shoaib , Algethami Abdullah , Alsehli Mishal
Published: March 2022

This work finds its motivation in heat exchanger design and flow control. Flow-induced vibration is studied numerically for combined vortex-induced vibrations and vortex-induced rotations of a horizontally positioned elliptic cylinder. The aspect ratio is taken as 2, and the value of reduced velocities (Ured) considered for the present simulation is between 2 and 12. The body can have to and fro motions in a transverse (y) direction, in-line (x) direction as well as in azimuthal (θ) direction, which provides three degrees of freedom (DOF) to the body. It is found that for one-DOF (y-direction only) and two-DOF (y and x directions) cases, lock-in regions are the same while it is wider for the case of the three-DOF system. With the rotational DOF, y-directional motion is amplified and when it is compared with the one-DOF and two-DOF cases, difference in peak amplitude is about 30%. The rotational response reaches a maximum value within the synchronization regime, and the frequency behavior of rotational and transverse oscillations is showing the same characteristics. The phase difference is plotted to check their synchronization with respective forces and moments. For all DOFs and Ured, synchronized or desynchronized regions, 2S mode of vortex shedding was observed. For one-DOF and two-DOF cases, the transverse vibrational frequency ratio (fy/fn) becomes equal to unity for the range 3.75≤Ured≤5. For three-DOF, fy/fn and rotational frequency ratio (fR/fn) become close to the unity for 3.75≤Ured≤6. The three-DOF system shows smaller wake width and vortex formation length whereas the vortex strength is maximum.
The starting dates of COVID-19 multiple waves
Authors: de Lima Gianfelice Paulo Roberto , Sovek Oyarzabal Ricardo , Cunha Americo , Vicensi Grzybowski Jose Mario , da Conceição Batista Fernando , E. N. Macau Elbert
Published: March 2022

The severe acute respiratory syndrome of coronavirus 2 spread globally very quickly, causing great concern at the international level due to the severity of the associated respiratory disease, the so-called COVID-19. Considering Rio de Janeiro city (Brazil) as an example, the first diagnosis of this disease occurred in March 2020, but the exact moment when the local spread of the virus started is uncertain as the Brazilian epidemiological surveillance system was not widely prepared to detect suspected cases of COVID-19 at that time. Improvements in this surveillance system occurred over the pandemic, but due to the complex nature of the disease transmission process, specifying the exact moment of emergence of new community contagion outbreaks is a complicated task. This work aims to propose a general methodology to determine possible start dates for the multiple community outbreaks of COVID-19, using for this purpose a parametric statistical approach that combines surveillance data, nonlinear regression, and information criteria to obtain a statistical model capable of describing the multiple waves of contagion observed. The dynamics of COVID-19 in the city of Rio de Janeiro is taken as a case study, and the results suggest that the original strain of the virus was already circulating in Rio de Janeiro city as early as late February 2020, probably being massively disseminated in the population during the carnival festivities.
Plasmonic enhancement in deep ultraviolet photoresponse of hexagonal boron nitride thin films
Authors: Zhu Xingrui , Chen Le , Tang Xuemei , Wang Hongyan , Xiao Yuhan , Gao Wei , Yin Hong
Published: March 2022

Deep-ultraviolet (DUV) photodetectors based on hexagonal boron nitride (h-BN) have demonstrated great potentials for various commercial and military applications; however, to date, most studies show that the h-BN photodetectors suffer from poor performance, such as low responsivity and large dark current. Herein, we report the dramatic enhancement of photoresponse in the DUV region of a h-BN device coupled with plasmonic nanostructures of either h-BN nanosheets (BNNSs) or Au nanoparticles (NPs). Large-area h-BN thin films that have been directly grown on quartz substrates using the ion beam assistant deposition method exhibit a uniform thickness of ∼200 nm, an ultrawide bandgap (∼ 6 eV), and an excellent light transparency in the visible region. Based on the vertical charge transfer integrated with plasmonic nanoarrays, the photocurrent of the h-BN device can be greatly enhanced by up to about 7–9 times under the illumination of 205 nm by showing a cutoff wavelength at ∼220 nm. Owing to the retained low dark current and large photo-gain induced by localized plasmonic resonances, this hybrid photodetector exhibits 32- and 57-fold improvement in responsivity at a 205 nm wavelength by BNNSs and Au NPs, respectively. This work demonstrates plasmonic enhancement on optoelectronic properties of h-BN based on not only metallic but also semiconducting nanostructures and provides alternative pathways for the development of low-cost, large-area, high-performance, DUV photodetectors for various optoelectronic devices and security applications.
Strain lithography for two-dimensional materials by electron irradiation
Authors: Du Shuo , Guo Yang , Huang Xin , Sun Chi , Zhang Zhaoqian , Hu Leyong , Zheng Ruixuan , Bai Qinghu , Jin Aizi , Yang Haifang , Zhang Yanfeng , Li Junjie , Gu Changzhi
Published: March 2022

Strain engineering, aiming to tune physical properties of semiconductors, provides a promising paradigm for modern micro/nanoelectronics. Two-dimensional materials (2DMs) are the ideal candidates for the next generation of strain engineered devices because of their intrinsic exceptional mechanical flexibility and strength. However, conventional strain modulation methods in 2DMs cannot satisfy the demand of future device applications, because strained structures by these methods lack consistency, reproducibility, and design flexibility. Here, based on the photoresist degeneration induced by electron irradiation, we present a non-contact approach to accurately and directly write the strains with designed patterns from the nanometer to micrometer scale in 2DMs. Profit from controllable manipulation of the electron beam, the developed strategy offers a capability for constructing tensile, compress, or complex strains in MoSe2 monolayers; hence, unique electronic structures for unique physical properties can be designed. Aside from 2DMs, this approach is also appropriate for other types of materials such as Au, α-Si, and Al2O3. Its flexibility and IC-compatibility allow our strain lithography methodology promising in accelerating the potential applications of 2DMs in extensive fields ranging from nanoelectromechanical systems, high-performance sensing, and nontraditional photovoltaics to quantum information science.
Critical behavior and strongly anisotropic interactions in PrMn2Ge2
Authors: Song Meng , Zhao Jun , Liu Caixing , He Miao , Wang Yihao , Han Yuyan , Ling Langsheng , Cao Liang , Zhang Lei , Qu Zhe , Xiong Yimin
Published: March 2022

Understanding the mechanisms for forming skyrmionic spin configurations at room temperature is essential for exploring the applicable spintronics devices based on topological spin textures. In this work, the anisotropic magnetic properties and critical behavior are investigated in noncollinear itinerant magnet PrMn2Ge2. The strongly anisotropic magnetic interactions and magnetic field and temperature induced antiferromagnetic to ferromagnetic transition are observed. The critical behavior of high temperature ferromagnetic transition at 331 K was analyzed, and the critical exponents β = 0.335, γ = 0.878, and δ = 3.617 are extracted by the modified Arrott plot method, which lie between the values of long-range mean-field and short-range three-dimensional theories, demonstrating that PrMn2Ge2 possesses multiple magnetic interactions. This is also confirmed by the moderated interaction function, which is decay as J(r) ∼ r−4.69. Therefore, the competition of multiple magnetic interactions in PrMn2Ge2 is analogous to what has been observed in GdRu2Si2 and could be the origin of skyrmionic bubbles observed at room temperature.
Effects of Reynolds number and average angle of attack on the laminar scaling of oscillating foils
Authors: Verma Suyash , Freeman Benjamin R. S. , Hemmati Arman
Published: March 2022

The variation in thrust generation with respect to Reynolds number was numerically evaluated for an oscillating foil with combined pitching and heaving motion at a range of reduced frequencies, amplitudes, and phase offsets. Laminar scaling (Re−0.5) was found accurate for a reasonable range of average angle of attack (α¯<20°). However, quantitative evaluation of laminar scaling using statistical measures indicates that its capability in predicting thrust variation weakens at higher reduced frequencies and amplitudes. This coincides with an increase in α¯ above 20°. Evaluation of the pressure and viscous forces revealed a dominance of the former toward total thrust generated at high frequencies for all cases, which also coincided with lower coefficient of determination (R2) for laminar scaling. The chordwise variation of pressure and skin friction coefficient provided further evidence indicating that pressure, in contrast to the skin friction, did not achieve an asymptotic trend with increasing Reynolds number, especially at higher frequencies and for all phase offsets. Qualitative evaluation of the developing leading edge vortex structure at increasing reduced frequencies and Reynolds numbers also supported the quantitative assessment of chordwise pressure variations. Empirical incorporation of Reynolds number into the complete scaling model was hence completed, which further validates the laminar scaling (Re−0.5) of propulsive thrust generation in oscillating foils with a coupled motion.
Electron-only reconnection and associated electron heating and acceleration in PHASMA
Authors: Shi Peiyun , Srivastav Prabhakar , Barbhuiya M. Hasan , Cassak Paul A. , Scime Earl E. , Swisdak M. , Beatty Cuyler , Gilbert Tyler , John Regis , Lazo Matthew , Nirwan Ripudaman Singh , Paul Mitchell , Scime Ethan E. , Stevenson Katey , Steinberger Thomas
Published: March 2022

Using incoherent Thomson scattering, electron heating and acceleration at the electron velocity distribution function (EVDF) level are investigated during electron-only reconnection in the PHAse Space MApping (PHASMA) facility. Reconnection arises during the merger of two kink-free flux ropes. Both push and pull type reconnection occur in a single discharge. Electron heating is localized around the separatrix, and the electron temperature increases continuously along the separatrix with distance from the X-line. The local measured gain in enthalpy flux is up to 70% of the incoming Poynting flux. Notably, non-Maxwellian EVDFs comprised of a warm bulk population and a cold beam are directly measured during the electron-only reconnection. The electron beam velocity is comparable to, and scales with, electron Alfvén speed, revealing the signature of electron acceleration caused by electron-only reconnection. The observation of oppositely directed electron beams on either side of the X-point provides “smoking-gun” evidence of the occurrence of electron-only reconnection in PHASMA. 2D particle-in-cell simulations agree well with the laboratory measurements. The measured conversion of Poynting flux into electron enthalpy is consistent with recent observations of electron-only reconnection in the magnetosheath [Phan et al., Nature 557, 202 (2018)] at similar dimensionless parameters as in the experiments. The laboratory measurements go beyond the magnetosheath observations by directly resolving the electron temperature gain.
Hole opening from growing interfacial voids: A possible mechanism of solid state dewetting
Authors: Curiotto Stefano , Chame Anna , Müller Pierre , Thompson Carl V. , Pierre-Louis Olivier
Published: March 2022

Vacancies at interfaces between a film and a substrate can affect material properties and could play a role in solid state dewetting. Using kinetic Monte Carlo simulations, we show that interfacial mono-vacancies diffuse and coalesce to form vacancy clusters and voids. The film/substrate excess energy ES, which is related to the apparent contact angle, controls the mechanisms of coalescence. Depending on ES, voids emerging at the film surface form a hole that can be filled by the film or can lead to dewetting of the film from the substrate.
Flapping wing propulsion: Comparison between discrete vortex method and other models
Authors: Faure T. M. , Roncin K. , Viaud B. , Simonet T. , Daridon L.
Published: March 2022

Cetacean propulsion by a periodic flapping motion of their fluke is considered and studied on a benchmark flexible straight wing. The aim of the study was to validate low-order models for this configuration. First, the two-dimensional rigid case is investigated, comparing the aerodynamic performance of the airfoil periodic motion vs the reduced frequency, with published data and unsteady Reynolds-averaged numerical simulation results. It appears that viscous drag modeling must be added to the discrete vortex method, in order to obtain sensible thrust results, for Garrick frequencies below 2. All high- and low-order models agree at the remarkable Garrick frequency of 1.82, although the experiment shows a lower efficiency of about 25%. The positions of the shed vortices match comparing the unsteady Reynolds-averaged numerical simulation and the discrete vortex method. Then, the three-dimensional leading-edge-suction-parameter modulated discrete vortex method is extended, by means of a lifting line theory. A modification of the method is proposed in order to consider wing dihedral, resulting from the spanwise flexibility. The configuration considers a reduced frequency of 1.82. Three types of spanwise wing flexibility are examined. For the inflexible and flexible cases, a reasonable agreement is observed between the different methods for each coefficient. The intermediate flexible wing provides a better thrust coefficient, while excessive flexibility proves to be detrimental. Vorticity fields are compared with previously published data for the three wings. For the highly flexible wing and the right choice of deformation parameters, the discrete vortex method produces reliable results.
Revisiting the single-saddle model for the β-relaxation of supercooled liquids
Authors: Coslovich Daniele , Ikeda Atsushi
Published: March 2022

The dynamics of glass-forming liquids display several outstanding features, such as two-step relaxation and dynamic heterogeneities, which are difficult to predict quantitatively from first principles. In this work, we revisit a simple theoretical model of the β-relaxation, i.e., the first step of the relaxation dynamics. The model, first introduced by Cavagna et al. [J. Phys. A: Math. Gen. 36, 10721 (2003)], describes the dynamics of the system in the neighborhood of a saddle point of the potential energy surface. We extend the model to account for density–density correlation functions and for the four-point dynamic susceptibility. We obtain analytical results for a simple schematic model, making contact with related results for p-spin models and with the predictions of inhomogeneous mode-coupling theory. Building on recent computational advances, we also explicitly compare the model predictions against overdamped Langevin dynamics simulations of a glass-forming liquid close to the mode-coupling crossover. The agreement is quantitative at the level of single-particle dynamic properties only up to the early β-regime. Due to its inherent harmonic approximation, however, the model is unable to predict the dynamics on the time scale relevant for structural relaxation. Nonetheless, our analysis suggests that the agreement with the simulations may be largely improved if the modes’ spatial localization is properly taken into account.
Controllable epitaxy of quasi-one-dimensional topological insulator α-Bi4Br4 for the application of saturable absorber
Authors: Zhang Xu , Xing Xiaowei , Li Ji , Peng Xianglin , Qiao Lu , Liu Yuxiang , Xiong Xiaolu , Han Junfeng , Liu Wenjun , Xiao Wende , Yao Yugui
Published: March 2022

Bismuth bromide (α-Bi4Br4) can demonstrate various exotic topological states, including higher-order topological insulator with hinge states and quantum spin Hall insulator with helical edge states. To date, α-Bi4Br4 nanowires can be obtained by using the exfoliation method from the bulk. However, it is still a great challenge to efficiently prepare α-Bi4Br4 nanowires suitable for potential applications, e.g., saturable absorber in ultrafast pulsed fiber lasers. Here, we report the controllable growth of α-Bi4Br4 thin films consisting of nanowires via molecular beam epitaxy technique. We show that the morphology of the α-Bi4Br4 nanowires depends on the growth temperature and BiBr3 flux. In addition, we also achieve α-Bi4Br4 nanowires on NbSe2 and gold substrates. Furthermore, we performed the saturable absorption property of α-Bi4Br4 thin films with a modulation depth of 21.58% and mode-locking at 1556.4 nm with a pulse width of 375 fs in the pulsed fiber lasers. Those results demonstrate the synthesis of quasi-1D topological material α-Bi4Br4, which is expected to be used for the fundamental research of topological physics and potential applications in optical devices.
A mixed deterministic–stochastic algorithm of the branching corrected mean field method for nonadiabatic dynamics
Authors: Li Bing , Xu Jiabo , Li Guijie , Shi Zhecun , Wang Linjun
Published: March 2022

We present a new algorithm of the branching corrected mean field (BCMF) method for nonadiabatic dynamics [J. Xu and L. Wang, J. Phys. Chem. Lett. 11, 8283 (2020)], which combines the key advantages of the two existed algorithms, i.e., the deterministic BCMF algorithm based on weights of trajectory branches (BCMF-w) and the stochastic BCMF algorithm with random collapse of the electronic wavefunction (BCMF-s). The resulting mixed deterministic–stochastic BCMF algorithm (BCMF-ws) is benchmarked in a series of standard scattering problems with potential wells on the excited-state surfaces, which are common in realistic systems. In all investigated cases, BCMF-ws holds the same high accuracy while the computational time is reduced about two orders of magnitude compared to the original BCMF-w and BCMF-s algorithms, thus promising for nonadiabatic dynamics simulations of general systems.
Wake waves of a planing boat: An experimental model
Authors: Tavakoli Sasan , Shaghaghi Poorya , Mancini Simone , De Luca Fabio , Dashtimanesh Abbas
Published: March 2022

The wake waves generated by the steady movement of a planing hull are analyzed by means of towing tank tests. Two sets of waves, including divergent and transverse waves, are identified and then analyzed. The wave period of the divergent waves is seen to decrease by the increase in speed of the vessel. These waves are seen to damp temporally. The mechanisms that lead to damping of the divergent wave were found to depend on the wave orbital Reynolds number in semi-planing regime, though that of in-planing regime is a function of the Reynolds number of the boat. The wake angle is seen to decrease with the increase in Froude number, the rate of which becomes relatively large in-planing regime. Transverse waves are captured through measurements, and it is shown that while their period is longer than those of the divergent waves, they are not noticeably damped. Throughout the spectral analysis, it is demonstrated that divergent waves reach a higher level of nonlinearity by the increase in Froude number and, hence, the wave energy is distributed over a boarder range of frequency. The height of the transverse wave is observed to become lower by the increase in speed, but as the towing speed increases, the probability density function curves of surface elevation deviate more and more from the Gaussian distribution.
Numerical simulation on transportation behavior of dense coarse particles in vertical pipe with an optimized Eulerian–Lagrangian method
Authors: Zhang Yan , Lu Xiao-Bing , Zhang Xu-Hui
Published: March 2022

Solid–liquid two-phase flow with dense coarse particles in the pipeline exists widely in energy and resources engineering, especially in the prospective hydraulic lifting scenario of deep-sea mining. In this paper, the coarse particles' transportation behavior in a vertical pipe is investigated based on an optimized Eulerian–Lagrangian method proposed in our previous work. The coarse particle transportation in the vertical pipe is characterized as multi-processes and multi-physical effects and is not fully captured due to the limitations on experimental apparatus, experimental measurement techniques, and numerical simulation techniques. Little research has been done on the local characteristics of the flow and their effect on the hydraulic lifting performance. The characteristics of the internal flow field, particle retention, and hydraulic lifting efficiency are disturbed under the condition of the continuous supply with the constant inlet two-phase concentration and velocity. The simulation results illustrate that particle transportation process can be roughly divided into three stages, single phase flow stage, mixing stage, and stable transportation stage, and shows a dilute-dense non-continuous flow pattern due to particle retention. Based on parametric studies, the retention phenomenon is alleviated by the increase in the water inlet velocity and almost disappears at approximately 12 000 of the Reynolds number, where the flow pattern transition occurs. Finally, the hydraulic lifting performance, such as a critical lifting condition and the friction loss, is analyzed and the transition of flow pattern is discussed.
What do Abelian categories form?
Authors: Kaledin D. B.
Published: March 2022

Given two finitely presentable Abelian categories

and

, we outline a construction of an Abelian category of functors from

to

, which has nice 2-categorical properties and provides an explicit model for a stable category of stable functors between the derived categories of

and

. The construction is absolute, so it makes it possible to recover not only Hochschild cohomology but also Mac Lane cohomology.

Bibliography: 29 titles.
Spectrum of the Laplace operator on closed surfaces
Authors: Popov D. A.
Published: March 2022

A survey is given of classical and relatively recent results on the distribution of the eigenvalues of the Laplace operator on closed surfaces. For various classes of metrics the dependence of the behaviour of the second term in Weyl’s formula on the geometry of the geodesic flow is considered. Various versions of trace formulae are presented, along with ensuing identities for the spectrum. The case of a compact Riemann surface with the Poincaré metric is considered separately, with the use of Selberg’s formula. A number of results on the stochastic properties of the spectrum in connection with the theory of quantum chaos and the universality conjecture are presented.

Bibliography: 51 titles.
Australian health service organisation assessment outcome data for the first 2 years of implementing the Comprehensive Care Standard
Authors: Murgo Margherita , Dalli Angie
Published: March 2022

Objective To review implementation of the Comprehensive Care Standard (CCS) by evaluating assessment outcome data of Australian health service organisations (HSOs) from January 2019. The CCS was introduced with the National Safety and Quality Health Service (NSQHS) Standards (second edition). It has 36 actions and over 40 resources to support implementation. Methods Retrospective assessment outcome data submitted by accrediting agencies were examined to gauge progress of CCS implementation by considering met or other ratings of the CCS actions. Results There were 495 assessments completed between January 2019 and December 2020. Most (71% n = 352) HSOs met the requirements of the CCS after initial assessment. Seventy-four (15%) of the HSOs did not meet all the requirements and a further 58 (12%) HSOs were provided with recommendations to meet the actions. Conclusions There was indication of underperformance related to some actions in the CCS. The assessment data highlighted common issues for organisations including difficulties implementing governance processes, demonstrating effective care planning, implementing the end-of-life care actions and some minimising harm actions. Future evaluation of the implementation of the CCS may benefit from strengthening links between other safety and quality programs.
Integrating topic modeling and word embedding to characterize violent deaths
Authors: Arseniev-Koehler Alina , Cochran Susan D. , Mays Vickie M. , Chang Kai-Wei , Foster Jacob G.
Published: March 2022

Significance

We introduce an approach to identify latent topics in large-scale text data. Our approach integrates two prominent methods of computational text analysis: topic modeling and word embedding. We apply our approach to written narratives of violent death (e.g., suicides and homicides) in the National Violent Death Reporting System (NVDRS). Many of our topics reveal aspects of violent death not captured in existing classification schemes. We also extract gender bias in the topics themselves (e.g., a topic about long guns is particularly masculine). Our findings suggest new lines of research that could contribute to reducing suicides or homicides. Our methods are broadly applicable to text data and can unlock similar information in other administrative databases.
Black Lives Matter protests shift public discourse
Authors: Dunivin Zackary Okun , Yan Harry Yaojun , Ince Jelani , Rojas Fabio
Published: March 2022

Significance

This study uses large-scale news media and social media data to show that nationwide Black Lives Matter (BLM) protests occur concurrently with sharp increases in public attention to components of the BLM agenda. We also show that attention to BLM and related concepts is not limited to these brief periods of protest but is sustained after protest has ceased. This suggests that protest events incited a change in public awareness of BLM’s vision of social change and the dissemination of antiracist ideas into popular discourse.
Strategic identity signaling in heterogeneous networks
Authors: van der Does Tamara , Galesic Mirta , Dunivin Zackary Okun , Smaldino Paul E.
Published: March 2022

Significance

Much of online conversation today consists of signaling one’s political identity. Although many signals are obvious to everyone, others are covert, recognizable to one’s ingroup while obscured from the outgroup. This type of covert identity signaling is critical for collaborations in a diverse society, but measuring covert signals has been difficult, slowing down theoretical development. We develop a method to detect covert and overt signals in tweets posted before the 2020 US presidential election and use a behavioral experiment to test predictions of a mathematical theory of covert signaling. Our results show that covert political signaling is more common when the perceived audience is politically diverse and open doors to a better understanding of communication in politically polarized societies.
Dual-function Spot 42 RNA encodes a 15–amino acid protein that regulates the CRP transcription factor
Authors: Aoyama Jordan J. , Raina Medha , Zhong Aoshu , Storz Gisela
Published: March 2022

Significance

Dual-function RNAs base pair with target messenger RNAs as small regulatory RNAs and encode small protein regulators. However, only a limited number of these dual-function regulators have been identified. In this study, we show that a well-characterized base-pairing small RNA surprisingly also encodes a 15–amino acid protein. The very small protein binds the cyclic adenosine monophosphate receptor protein transcription factor to block activation of some promoters, raising the question of how many other transcription factors are modulated by unidentified small proteins.
Developing an empirically-driven aural multiple-choice DCT for conventional expressions in L2 pragmatics
Authors: Bardovi-Harlig Kathleen , Su Yunwen
Published: March 2022

This paper reports on the development of an aural multiple-choice discourse completion task (aural MC-DCT) for use with EFL learners for large-scale instructional needs assessment. The original version of the aural MC-DCT and an oral DCT were administered to 134 EFL learners from three universities in China. The aural MC-DCT was revised based on the results of the initial administration and completed by 251 EFL students and 89 native speakers of American English in a second administration. Both versions of the task used learner-generated options. The first version used digital files of learner production from an earlier oral DCT taken by ESL learners; the second version re-recorded the learner-produced options using native speakers of American English. The results from the second version show that the aural MC-DCT is a feasible format for exploring learner knowledge of conventional expressions by comparing learner selections to production on the oral DCT, which has been established as a reliable measure of L2 English conventional expressions. The aural MC-DCT provides teachers with a practical alternative to the transcription and analysis required by the oral DCT, allowing them to easily assess knowledge of target conventional expressions and preferred alternatives in order to facilitate decisions about instruction.
The relationship between training characteristics and durability in professional cyclists across a competitive season
Authors: Spragg James , Leo Peter , Swart Jeroen
Published: March 2022

This study investigated the influence of training characteristics on the fatigued power profile in professional cyclists. Data was collected from 30 under 23 professional cyclists (age: 20.1 ± 1.1 years, body mass: 69 ± 6.9 kg, height: 182.6 ± 6.2 cm, O2max: 73.8 ± 2.5 mL·kg−1·min−1, CP: 5.48 ± 0.38 W·kg−1, W´: 17.83 ± 3.57 kJ) across a competitive season and collated in to 3 periods: early‐, mid‐ and late‐season. Two power profiles (fresh and fatigued) were created from absolute (W) and relative (W·kg−1) 2‐, 5‐, and 12‐min maximal mean power outputs. The fresh power profile consisted exclusively of power output values produced prior to 2000 kJ work (2MMPfresh, 5MMPfresh and 12MMPfresh) while the fatigued power profile consisted of power output values produced exclusively post 2000 kJ (2MMPfatigue 5MMPfatigue and 12MMPfatigue). Training characteristics were analysed to assess their influence on the power profiles. Absolute 5MMPfatigue, 12MMPfatigue and relative 12MMPfatigue were significantly lower in late‐season compared with early‐ and mid‐season (p < 0.05). The difference in absolute 12MMPfresh and 12MMPfatigue was significantly greater in late than in early‐ and mid‐season. A significant relationship was found between training time below the first ventilatory threshold (Time < VT1) and improvements in absolute and relative 2MMPfatigue (r = 0.43 p = 0.018 and r = 0.376 p = 0.04 respectively); and between a shift towards a polarized training intensity distribution and improvements in absolute and relative 12MMPfatigue (r = 0.414 p = 0.023 for both) between subsequent periods. In conclusion, there is greater variability in the fatigue power profile across a competitive season than the fresh power profile.

Highlights

The fatigued power profile varies throughout a competitive season

The difference between the fresh and fatigued power profiles is not fixed across a competitive season

A tendency towards a polarized training intensity distribution is associated with an improvement in the fatigue power profile
The Yukawa interaction in ordinary quantum mechanics
Authors: Schubring Daniel
Published: March 2022

The Yukawa interaction is considered in 0 + 1 dimensions as a pedagogical example to illustrate quantum field theory methods. From the quantum mechanical point of view the system is trivially exactly solvable, but this can be difficult to see from the path integral perspective. It is shown how despite initial appearances the perturbation series in terms of Feynman diagrams is consistent with the quantum mechanical picture for finite temperature.
Micromechanical resonant cantilever sensors actuated by fringing electrostatic fields
Authors: Krakover Naftaly , Ilic B Robert , Krylov Slava
Published: March 2022

We report on the architecture and operational principle of a resonant cantilever-type displacement sensor. The device is actuated electrostatically by a side electrode that is coplanar with the cantilever and by a gap-closing electrode positioned underneath the beam. The unique electrode geometry combined with the appropriate actuating voltages allows positioning of the cantilever in close proximity to the bistability threshold, where the frequency sensitivity to the electrode displacement is enhanced. Using a reduced order model backed by numerical simulations, the dependencies of the device frequency on the beam’s deflections and the actuation voltages were mapped. We show wide-range tunability that spans a range between softening and hardening behavior. We demonstrate displacement sensing using fabricated single crystal silicon ≈2000 µm long, ≈5 µm thick cantilevers. When compared to a resonant cantilever sensor actuated solely by a gap-closing electrode, measurements from our fringing field actuated devices show a four times higher sensitivity of ≈98 Hz µm−1. The suggested approach may find applications in a broad range of micro and potentially nano-scale applications including resonant inertial, force, mass and bio-sensors.
An electrochemical biosensor with integrated microheater to improve the sensitivity of electrochemical nucleic acid biosensors
Authors: Akcakoca Iremnur , Ghorbanpoor Hamed , Blair Ewen , Ozturk Yasin , Norouz Dizaji Araz , Kocagoz Tanil , Avci Huseyin , Corrigan Damion , Dogan Guzel Fatma
Published: March 2022

Electrochemical impedance spectroscopy is often used for biomolecular detection based on the interaction of a molecule with a receptor functionalised electrode surface and consequent impedance change. Though its performance is well established, there is still a need for improved sensitivity and specificity, especially when attempting to detect nucleic acids from clinical samples with minimal amplification steps. Localised heating is a potential approach for improving nucleic hybridisation rates and reducing non-specific interactions, and thereby producing high sensitivity and selectivity. The aim of the study was therefore to develop a microheater surrounding Au thin film electrodes, an integrated hybrid chip, for detecting genes of Mycobacterium tuberculosis with enhanced sensitivity. The performance of the integrated hybrid chip was determined using the changes in the charge transfer resistance (R
ct) upon DNA hybridisation using probe sequences for M. tuberculosis. Heat transfer within the system was simulated by using COMSOL Multiphysics as a mathematical modelling tool. When a temperature of 50 °C was applied to the microheater during DNA hybridisation steps, R
ct values (which were indicative of DNA–DNA hybridisation) increased 236% and 90% as opposed to off-chip non-heated experiments and off-chip heated experiments. It is concluded from these observations that the microheater indeed can significantly improve the performance of the nucleic acid hybridisation assay and paves the way for the development of highly sensitive and specific integrated label-free biosensors.
Magnetic and electrical transport studies of polycrystalline Sr1−

x
Bi
x
Fe12O19 (x = 0, 0.01, and 0.02)
Authors: Sahoo M R , Barik A , Kuila S , Tiwary Sweta , Ghosh R , Babu P D , Kaushik S D , Vishwakarma P N
Published: March 2022

Bismuth-substituted strontium hexaferrites, Sr1−x
Bi
x
Fe12O19 for x = 0, 0.01 and 0.02, are studied via powder neutron diffraction (ND), magnetization (M) studies, Mössbauer spectroscopy, and electrical transport. ND results show an indication of increasing Fe2+ at 12k crystallographic sites (which is supported by Mössbauer results), with increasing Bi in the sample. They also suggest an increase in strain due to Bi substitution for the polyhedral associated with 2a and 2b spin-up and 4f1 spin-down sites. The M measurements over a wide temperature range (3–823 K), shows irreversibility in zero field cooled (ZFC) and field cooled data right below the Curie temperature, along with the Hopkinson peak in the ZFC data. The temperature dependence of saturated magnetization follows the Bloch relation but that of the coercive field shows unconventional behavior. The coercive field data is fitted using an equation devised by taking into consideration of all the three anisotropies. The critical exponents at the ferromagnetic–paramagnetic phase transition boundary, calculated using modified Arrott plots, are slightly overvalued as per mean-field theory. The temperature dependence of resistivity displays nearest-neighbor hopping conduction in all the three samples. The conductivity increases with increasing Bi in the sample, due to the increasing Fe2+ content, which facilitates the electron hopping between Fe sites. The magnetoresistance measured at various sub-room temperatures for all the compounds shows the interplay of anisotropy magnetoresistance (AMR) and giant magnetoresistance (GMR). Low temperature data are dominated by GMR and gradual participation of AMR increases as room temperature is approached.
Symmetries of the oblate deformed harmonic oscillator
Authors: Freer Martin , Marsh Thomas , Souter James
Published: March 2022

A study of oblate shell closures of the deformed harmonic oscillator (HO) shows that the associated magic numbers are linked to a universal sequence of the triangular numbers (1, 3, 6, 10, 15, 21…) which describe equally prolate, spherical and oblate structures. This provides a new basis for the understanding of the deformed HO. The consequences for oblate nuclei are discussed, in particular 12C and 28Si.
Elucidate interfacial disorder effects on the perpendicular magnetic anisotropy at Fe/MgO heterostructure from first-principles calculations
Authors: Nazir Safdar , Yang Kesong
Published: March 2022

The interfacial perpendicular magnetic anisotropy (PMA) plays a key role in spintronic applications such as memory recording and computational devices. Despite robust PMA being reported at the Fe/MgO interface, there are still inconsistencies in the disorder effects on the interfacial magnetic anisotropy. Here we reported a comprehensive study of the influence of the interfacial disorder, including the underoxidization, overoxidization, and oxygen migration, on the PMA of the Fe/MgO interface using first-principles calculations. Compared to the pristine Fe/MgO interface, the underoxidation at the Fe/MgO interface keeps the interfacial PMA but reduces the interfacial anisotropy constant (K

i
). The overoxidization and oxygen migration at the interface both reduce the K

i
and even switch the easy magnetization axis from the out-of-plane to in-plane direction at high oxygen percentage. In all the cases, the K

i
was found strongly correlated to the difference of the orbital magnetic moment along the in-plane and out-of-plane direction. Calculated layer-resolved and orbital-resolved K

i
revealed that the orbital coupling between the d

xy
and

d

x

2

−

y

2

states of the interfacial Fe layer plays a key role in determining the interfacial magnetic anisotropy. This work provides deep insights into the oxidation effects on the interfacial magnetic anisotropy of Fe/MgO system and a possible avenue to tune the K

i
via interfacial engineering.
A hybrid FBG-based load and vibration transducer with a 3D fused deposition modelling approach
Authors: Xu Dong-Sheng , Su Zi-Qiang , Lalit Borana , Qin Yue
Published: March 2022

A fibre Bragg grating (FBG)-based load and vibration transducer (FLVT) was developed using a 3D fused deposition modelling (FDM) approach. A newly FLVT was designed by the equal-strength cantilever beam in which the FBG sensors were embedded in the beam during the FDM process. The temperature effect was eliminated by the temperature sensor in the vibration sensing unit. The parameters of the proposed FLVT was examined by the finite element method. The simulated results were matched well with the theoretical analysis results and laboratory calibration results. The proposed transducer has the pressure measurement sensitivity of 0.01274 nm kPa−1 for the earth pressure below 150 kPa. In addition, the proposed transducer could accurately measure low-frequency vibration signals with maximum frequency of 4 Hz and the maximum displacement amplitude of 4 mm with sensitivity of 117.6 pm g−1. The measurement accuracy and stability were carried out. Results shown that the maximum relative errors between the calculation results and the experimental results was 1.3%. The effect of vibration direction was also analysed for the proposed FLVT. The results indicated that the transversal vibration has less influence on the longitudinal vibration. The outcome of this study indicated that the proposed FLVT provide a newly approach for the measurement of earth pressure and soil vibration in one transducer which is quit suit for soil mass.
A solution-processed octahedral nano-blocks structure CaIn2S4 film for UV/vis photodetection
Authors: Rong Ping , Liu Yi , Gao Shiyong , Lu Huiqing , Ren Shuai , Li Lin , Ma Xinzhi , Zhou Qicheng , Chen Junpei , Wang Jinzhong
Published: March 2022

A novel CaIn2S4 with three-dimensional octahedral nano-blocks (ONBs) are successfully synthesized on fluorine-doped tin oxide (FTO) substrate by a simple hydrothermal method. The CaIn2S4 ONBs are uniform grown and scattered on the whole FTO substrate with high regular and symmetric morphology as well as average diagonal length of about 600 nm. Based on the as-synthesized CaIn2S4 ONBs, a photodetector (PD) is fabricated. Satisfyingly, it is found that the CaIn2S4 ONBs PD achieves a broad-band response ranging from ultraviolet (UV) to visible ( vis) light at zero bias voltage. It is also significant that the CaIn2S4 ONBs PD enables a fast response, in which the rise time and decay time are less than 0.15 and 0.2 s, respectively. Furthermore, the morphological evolution of the CaIn2S4 ONBs and plausible UV/vis detection mechanism of the CaIn2S4 ONBs PD are discussed.
Surface nanostructuring of alkali-aluminosilicate Gorilla display glass substrates using a maskless process
Authors: Cao Rongtao , Zhou Ziyu , Haghanifar Sajad , Wu Jingyu , Li Ming-Jun , Tan Susheng , Leu Paul W , Chen Kevin P
Published: March 2022

This paper reports on the formation of moth-eye nanopillar structures on surfaces of alkali-aluminosilicate Gorilla glass substrates using a self-masking plasma etching method. Surface and cross-section chemical compositions studies were carried out to study the formation of the nanostructures. CF
x
induced polymers were shown to be the self-masking material during plasma etching. The nanostructures enhance transmission at wavelengths over 525 nm may be utilized for fluid-induced switchable haze. Additional functionalities associated with nanostructures may be realized such as self-cleaning, anti-fogging, and stain-resistance.