bluuebunny/crossref_metadata_2025 huggingface dataset:
Overcoming anomalous suppression of m-plane AlGaN growth by molecular-beam epitaxy using indium as a surfactant
Authors: Dzuba Brandon , Nguyen Trang , Cao Yang , Diaz Rosa E. , Manfra Michael J. , Malis Oana
Published: September 2021

Anomalous growth rate reduction and associated composition divergence with increasing aluminum flux in m-plane AlGaN grown by plasma-assisted molecular beam epitaxy at low temperature (565 °C) are observed and investigated. We find that the AlGaN growth rate under conventional gallium-rich conditions decreases rapidly with increasing aluminum flux, contrary to expectations. Moreover, the aluminum fraction of these layers increases super-linearly with aluminum flux, indicating substantial nitrogen and gallium loss from the crystal surface. Indium surfactant assisted epitaxy (ISAE) is found to mitigate this effect significantly. ISAE AlGaN layers do not exhibit a significant decrease in the growth rate with increasing aluminum flux, and their aluminum compositions increase linearly with aluminum flux. Transmission electron microscopy (TEM) images reveal the presence of high-aluminum composition defects within the conventionally grown AlGaN layers, which are significantly reduced in ISAE AlGaN layers. Spatial correlation of these defects with local areas of reduced growth rate observed in an (In)Al0.30Ga0.70N/In0.16Ga0.84N multiple quantum well (MQW) structure suggests that these phenomena have a causal relationship. We attribute the growth rate reduction to the loss of nitrogen and gallium due to site-blocking effects of aluminum adatoms. TEM imaging indicates that high-quality, virtually defect-free (In)Al0.24Ga0.76N/In0.16Ga0.84N MQWs can be grown at 565 °C with negligible indium incorporation into the barriers.
Coherent super-radiative undulator emission of ultra-short THz wave pulses
Authors: Oparina Yulia S. , Savilov Andrei V.
Published: September 2021

We study spontaneous coherent super-radiative undulator emission in the terahertz frequency range from a short (as compared to the wavelength of the radiated wave), dense electron bunch. Since the group velocity of the wave is close to the bunch velocity, this is a process of spontaneous radiation followed by amplification of a single wave cycle. Despite the Coulomb repulsion of electrons inside the bunch, its compactness, which is necessary to ensure the spontaneous coherent character of the radiation process, is provided by the compression of the bunch under the action of its own radiation fields. As a result, formation of an ultra-short (several cycles long) powerful wave packet occurs when the bunch moves through several undulator periods with high (∼20% in optimized profiled systems) efficiency of extraction of the electron energy and high intensity (∼100 MV/m) of the peak wave field.
Generalized Gelfand–Yaglom formula for a discretized quantum mechanic system
Authors: Shea Meredith
Published: September 2021

The Gelfand–Yaglom formula relates the regularized determinant of a differential operator to the solution of an initial value problem. Here, we develop a generalized Gelfand–Yaglom formula for a Hamiltonian system with Lagrangian boundary conditions in the discrete and continuous settings. Later, we analyze the convergence of the discretized Hamilton–Jacobi operator and propose a lattice regularization for the determinant.
Bandgap of two-dimensional materials: Thorough assessment of modern exchange–correlation functionals
Authors: Tran Fabien , Doumont Jan , Kalantari Leila , Blaha Peter , Rauch Tomáš , Borlido Pedro , Botti Silvana , Marques Miguel A. L. , Patra Abhilash , Jana Subrata , Samal Prasanjit
Published: September 2021

The density-functional theory (DFT) approximations that are the most accurate for the calculation of bandgap of bulk materials are hybrid functionals, such as HSE06, the modified Becke–Johnson (MBJ) potential, and the GLLB-SC potential. More recently, generalized gradient approximations (GGAs), such as HLE16, or meta-GGAs, such as (m)TASK, have also proven to be quite accurate for the bandgap. Here, the focus is on two-dimensional (2D) materials and the goal is to provide a broad overview of the performance of DFT functionals by considering a large test set of 298 2D systems. The present work is an extension of our recent studies [T. Rauch, M. A. L. Marques, and S. Botti, Phys. Rev. B 101, 245163 (2020); Patra et al., J. Phys. Chem. C 125, 11206 (2021)]. Due to the lack of experimental results for the bandgap of 2D systems, G0W0 results were taken as reference. It is shown that the GLLB-SC potential and mTASK functional provide the bandgaps that are the closest to G0W0. Following closely, the local MBJ potential has a pretty good accuracy that is similar to the accuracy of the more expensive hybrid functional HSE06.
Exponential distribution of lifetimes for transient bursting states in coupled noisy excitable systems
Authors: Albanbay Nurtay , Medetov Bekbolat , Zaks Michael A.
Published: September 2021

The phenomenon of transient bursting, caused by additive noise in a set of two coupled FitzHugh–Nagumo oscillators, is studied by direct numerical integration and by measurements in the analog electronic circuit. In the parameter region where the unique global attractor of the deterministic system is the state of rest, introduction of low or moderate intensity fluctuations into the voltage dynamics results in the onset of a transient bursting state: sequences of intermittent bursts (patches of spikes), followed by ultimate relaxation to the equilibrium. Like genuine deterministic bursting, this behavior has its origin in the slow–fast character of the underlying dynamics. Trajectories that in the deterministic variant would converge to the state of rest can, under the action of noise, escape the local basin of attraction of the equilibrium and experience a bursting episode, before being dynamically reinjected into the region around the equilibrium. Under frozen parameter values and fixed noise intensity, the number of bursts preceding the ultimate decay strongly varies for different realizations of the additive random signal. The average duration of the transient bursting stage, bounded for weak noise, diverges when the intensity of fluctuations is raised. For sufficiently large ensembles of realizations, the lifetimes of transient bursting states, both in simulations and in the analog circuit, obey the exponential distribution. We relate this distribution to the probability for a stochastic trajectory to temporarily escape from the local basin of attraction of the equilibrium.
Ion transport in nanocrystalline CaF2 films
Authors: Usiskin Robert , Sigle Wilfried , Kelsch Marion , van Aken Peter A. , Maier Joachim
Published: September 2021

This work investigates the conductivity and structure of nanocrystalline CaF2 films grown at 200 °C by thermal evaporation. The in-plane conductivity is enhanced by several orders of magnitude compared to lightly doped bulk samples of CaF2, which independently confirms the finding of a previous work [Modine et al., J. Appl. Phys. 74, 2658 (1993)]. Upon heating above 200 °C, the enhancement is partially annealed out, and the activation energy increases continuously from 0.7 to 1.0 eV, which contradicts the annealing model proposed previously. The enhancement is seen only in an ∼20-nm thick region adjacent to the substrate, but this may be because the films show substantial porosity outside this region. A 5–10 nm grain size and a high density of grain boundaries are observed by high-resolution transmission electron microscopy. A 2–4 nm interfacial amorphous layer is seen in films grown on Al2O3, but such a layer is absent on MgO and evidently not responsible for the enhanced conduction. Overall, the evidence points to grain boundaries and/or dislocations as providing fast transport pathways. These results help to reconcile previous reports of enhanced ion transport in CaF2, and they are also relevant for understanding the enhancement mechanism in CaF2-based composites and antifluorite-structured materials such as Li2O.
Duration and distance of a laser-driven shock wave formation in a plasma with subcritical density
Authors: Gus'kov S. Yu. , Kuchugov P. A. , Yakhin R. A.
Published: September 2021

Theory and computational results are presented through the generation and propagation of a plane laser-driven shock wave in a substance with a density less than the critical plasma density. A model of the phenomenon is developed, the essence of which consists in the formation of pressure behind the front of the laser-driven ionization wave, which provides hydrodynamic motion with the speed exceeding the speed of the ionization wave front and the sound speed in unperturbed matter ahead of it. The dependences of the duration and distance of shock wave formation on the intensity and radiation wavelength of the impacting laser pulse, as well as on the density of the target substance, are established. The results are discussed for the conditions of irradiation of targets with a density up to 0.1 mg cm−3 by a pulse of short-wavelength radiation of the first–third harmonics of the Nd laser with an intensity of 1012−1015 W cm−2.
Control of single and multiple phase solitons in a ring cavity
Authors: Shafie Mohammad Mehdi , Kheradmand Reza , Ghahramani Mohammad , Prati Franco
Published: September 2021

Phase solitons are localized structures characterized by phase jumps of 2π or multiples arising in forced ring lasers. Here, we show numerically that they can be created by superimposing to the constant driving field a suitable control beam matched in frequency with a different cavity mode for a time of the order of ten cavity round trip times. If the two beams are separated in frequency by n free spectral ranges of the cavity, a train of solitons like a perfect soliton crystal consisting of n equispaced phase solitons is generated. This may represent a simple way to produce frequency combs with flexible frequency spacing and high power per line.
Optimization of 2.45 GHz microwave coupling depending on axial magnetic field profiles and impedance transformer in electron cyclotron resonance ion source
Authors: Jo Jong Gab , Jeong Seung Ho , Kim Tae-Seong , Kim S. H. , Park Min , Huh Sung-Ryul
Published: September 2021

The optimization of 2.45 GHz microwave coupling in an electron cyclotron resonance (ECR) ion source is investigated through experiments and full wave simulation studies. The axial magnetic field profile and an impedance transformer are the two major factors affecting the optimum power coupling. Experimental observations have shown that the beam current density increases when the two ECR zones are located in the plasma chamber and when the first ECR zone is close to the RF entrance. A coupling study with various magnetic field profiles finds that the gap distance between the RF window and first ECR zone and the effective ECR zone width determines the coupling efficiency. Optimum power coupling is obtained under the condition of an appropriately slight gap distance comparable to the half width of the effective ECR zone. The extracted beam current density increases when the second ECR zone becomes closer to the plasma grid. With the optimized axial magnetic field profile, impedance transformers are designed in consideration of reflection coefficient with respect to the plasma density. The performance of the impedance transformers is experimentally evaluated in terms of the efficiency (mA/W) with the findings consistent with the results of a simulation. The highest beam current density (∼165 mA/cm2) in these experiments is achieved with the optimized axial magnetic profile and the impedance transformer.
Super-broadband geometric phase devices based on circular polarization converter with mirror symmetry
Authors: Chen Wan , Yu Yang , Mu Quanquan , Campos Juan , Wang Qidong , Li Shixiao , Zhang Shiyuan , Xuan Li
Published: September 2021

We propose a simple implementation to obtain super-broadband geometric phase devices (GPD) by means of circular polarization converter (CPC) with mirror symmetry. We demonstrate that the best choice of wideband GPDs and CPCs is a mirror symmetric structure. Based on a two-rotation model on the Poincaré sphere, optimization parameters and time are significantly reduced. The CPC can be extended to super-broadband GPD, such as polarization gratings (PGs), by using geometric phase holography. We simulate diffraction efficiencies of the super-broadband PGs. In the normal incident case, the diffraction efficiency is over 99% in 420–945 nm, and in the oblique incident case, the first-order diffraction efficiency is over 90% in the range of ±30°. The super-broadband GPDs show potential advantages in wide color display and spectral imaging.
Calculation of improved enthalpy and entropy of vaporization by a modified partition function in quantum cluster equilibrium theory
Authors: Zaby Paul , Ingenmey Johannes , Kirchner Barbara , Grimme Stefan , Ehlert Sebastian
Published: September 2021

In this work, we present an altered partition function that leads to an improved calculation of the enthalpy and entropy of vaporization in the framework of quantum cluster equilibrium theory. The changes are based on a previously suggested modification [S. Grimme, Chem. Eur. J. 18, 9955–9964 (2012)] of the molecular entropy calculation in the gas phase. Here, the low energy vibrational frequencies in the vibrational partition function are treated as hindered rotations instead of vibrations. The new scheme is tested on a set of nine organic solvents for the calculation of the enthalpy and entropy of vaporization. The enthalpies and entropies of vaporization show improvements from 6.5 error to 3.3 kJ mol−1 deviation to experiment and from 28.4 error to 13.5 J mol−1 K−1 deviation to experiment, respectively. The effect of the corrected partition function is visible in the different populations of clusters, which become physically more meaningful in that larger clusters are higher populated in the liquid phase and the gas phase is mainly populated by the monomers. Furthermore, the corrected partition function also overcomes technical difficulties and leads to an increased stability of the calculations in regard to the size of the cluster set.
Segregation on the nanoscale coupled to liquid water polyamorphism in supercooled aqueous ionic-liquid solution
Authors: Zanetti-Polzi Laura , Amadei Andrea , Daidone Isabella
Published: September 2021

The most intriguing hypothesis explaining many water anomalies is a metastable liquid–liquid phase transition (LLPT) at high pressure and low temperatures, experimentally hidden by homogeneous nucleation. Recent infrared spectroscopic experiments showed that upon addition of hydrazinium trifluoroacetate to water, the supercooled ionic solution undergoes a sharp, reversible LLPT at ambient pressure, possible offspring of that in pure water. Here, we calculate the temperature-dependent signature of the OH-stretching band, reporting on the low/high density phase of water, in neat water and in the same experimentally investigated ionic solution. The comparison between the infrared signature of the pure liquid and that of the ionic solution can be achieved only computationally, providing insight into the nature of the experimentally observed phase transition and allowing us to investigate the effects of ionic compounds on the high to low density supercooled liquid water transition. We show that the experimentally observed crossover behavior in the ionic solution can be reproduced only if the phase transition between the low- and high-density liquid states of water is coupled to a mixing–unmixing transition between the water component and the ions: at low temperatures, water and ions are separated and the water component is a low density liquid. At high temperatures, water and ions get mixed and the water component is a high-density liquid. The separation at low temperatures into ion-rich and ion-poor regions allows unveiling the polyamorphic nature of liquid water, leading to a crossover behavior resembling that observed in supercooled neat water under high pressure.
Stellarator optimization for good magnetic surfaces at the same time as quasisymmetry
Authors: Landreman Matt , Medasani Bharat , Zhu Caoxiang
Published: September 2021

A method is demonstrated to optimize a stellarator's geometry to eliminate magnetic islands and achieve other desired physics properties at the same time. For many physics quantities that have been used in stellarator optimization, including quasisymmetry, neoclassical transport, and magnetohydrodynamic stability, it is convenient to use a magnetic equilibrium representation that assures the existence of magnetic surfaces. However, this representation hides the possible presence of magnetic islands, which are typically undesirable. To include both surface-based objectives and island widths in a single optimization, two fixed-boundary equilibrium calculations are run at each iteration of the optimization: one that enforces the existence of magnetic surfaces (the Variational Moments Equilibrium Code) [S. P. Hirshman and J. C. Whitson, Phys. Fluids 26, 3553 (1983)] and one that does not (the Stepped Pressure Equilibrium Code) [Hudson et al., Phys. Plasmas 19, 112502 (2012)]. By penalizing the island residues in the objective function, the two magnetic field representations are brought into agreement during the optimization. An example is presented in which, particularly on the surface where quasisymmetry was targeted, quasisymmetry is achieved more accurately than in previously published examples.
Steering performance of ultrasonic phased array sensors using acoustic fields under directivity constraint
Authors: Zhao Xia , Wang Zhaoba
Published: September 2021

Ultrasonic phased array sensors consist of multiple elements excited by predetermined time-delayed pulses. The directivity of each element was used to propose a sound field calculation model that adds a directivity constraint for each element. The steering sound fields under different directivity constraints were simulated, and the results demonstrate that the directivity of each element significantly impacts the overall steering of sound beams. This demonstrates the feasibility of adding a directivity constraint when modeling sensor arrays. This brings the simulation results closer to actual sound propagation and provides more accurate technical support in the design and use of phased array sensor applications.
High-order gas-kinetic scheme on three-dimensional unstructured meshes for compressible flows
Authors: Yang Yaqing , Pan Liang , Xu Kun
Published: September 2021

In this paper, a high-order gas-kinetic scheme is developed on three-dimensional unstructured meshes for compressible Euler and Navier–Stokes equations. To achieve the high-order spatial accuracy, the three-dimensional weighted essentially non-oscillatory (WENO) reconstruction is extended to the unstructured tetrahedral and hexahedral meshes. A simple strategy is adopted for the selection of candidate stencils, and the topologically independent linear weights are used for the spatial reconstruction. The efficiency and robustness of the classical WENO reconstruction are improved. In addition to the two-stage fourth-order temporal discretization and lower–upper symmetric Gauss–Seidel method, the explicit and implicit high-order gas-kinetic schemes are developed for unsteady and steady problems. Accuracy tests on hexahedral and tetrahedral grids validate the third-order of accuracy, and various three-dimensional incompressible and compressible numerical experiments are also presented. The results validate the accuracy and robustness of the proposed scheme for both inviscid and viscous flows. In the future, the current scheme will be extended to the hybrid unstructured meshes and Reynolds-averaged Navier–Stokes simulation with high Reynolds numbers.
Effect of auxiliary gas process on double-wire deposition morphology
Authors: Wu Wei , Xu Wei , Xue Jiaxiang , Yao Ping
Published: September 2021

Double-wire arc additive manufacturing could manufacture large-sized components at low cost and high efficiency; however, serious heat input and heat accumulation result in poor forming quality and limit further efficiency and application. An auxiliary gas process platform for double-wire additive manufacturing is introduced in this paper to explore the influence mechanism of the auxiliary gas on deposition during the manufacturing process. Monolayer and multilayer test results showed that the auxiliary gas had a stirring effect on a liquid molten pool and a cooling effect on deposition layers, and different auxiliary gas parameters could also influence the welding arc stability, which all acted on the deposition morphology. The angle between the auxiliary gas nozzle and welding torch had the greatest impact on the formation of components, followed by the auxiliary gas flow, and the auxiliary nozzle height had minimal influence. When the angle increased from 0° to 30°, the forming morphology gradually flowed. Furthermore, increasing the auxiliary gas flow rate led to the decreased sample height and a serious flowing defect. However, decreasing the nozzle height increased the gas pressure, which would also reduce the height.
Tree height is more important than bark thickness, leaf habit or habitat preference to survive fire in the cerrado of south-east Brazil
Authors: Rodriguez-Cubillo Dario , Pilon Natashi A. L. , Durigan Giselda
Published: September 2021

Although cerrado trees have evolved with fire for millions of years, it is not well-understood which tree attributes are more important to survive fire in the Brazilian savanna. To address this issue, we used pre- and post-fire data on 367 cerrado trees (113 native species) planted in an arboretum in south-east Brazil and then left unburnt until 2019, when a prescribed burn was applied. Tree size (height and diameter) had been measured in 2017. Four months after the fire, we assessed tree size, relative bark thickness (bark-to-diameter ratio), leaf habit (evergreen or deciduous) and habitat preference (savanna specialist or generalist). These were the predictor variables used in generalised linear models exploring tree survival and resprouting type. Most trees survived fire: 59% resprouted epicormically, 25% resprouted basally, 6% had root suckers, and only four trees died. Basal and epicormic resprouting were related to tree size: small trees (diameter ≤ 5 cm) resprouted basally more frequently, whereas tall trees (height ≥ 3.7 m) resprouted epicormically more frequently. Our results suggest that rapid growth is more important than bark thickness, leaf habit or habitat preference to escape the fire trap, because it allows cerrado trees to reach a fire-resistant height more quickly.
Lexical diachronic semantic maps
Authors: Georgakopoulos Thanasis , Polis Stéphane
Published: September 2021

This paper extends the scope of application of the semantic map model to diachronic lexical semantics. Combining a quantitative approach to large-scale synchronic polysemy data with a qualitative evaluation of the diachronic material in two text languages, ancient Egyptian and ancient Greek, it shows that weighted diachronic semantic maps can capture informative generalizations about the organization of the lexicon and its reshaping over time. The general methodology developed in the paper is illustrated with a case study of the semantic extension of time-related lexemes. This case study shows that the blend of tools well established in linguistic typology with proven methods of historical linguistics enables a principled approach to long-standing questions in the fields of diachronic semasiology and onomasiology.
Metaphors we teach by
Authors: Martin Hard Bridgette , Liang Nathan , Wong Michelle , Flusberg Stephen J.
Published: September 2021

Teaching is a complex activity that people often discuss metaphorically, as when a professor is described as a
sculptor molding impressionable students. What do such metaphors reveal about how people conceptualize teaching? Previous
work has addressed related questions largely via researcher intuition and qualitative analyses of teacher attitudes. We sought to develop a
more principled method for mapping the entailments of metaphorical concepts, using teaching metaphors as a case study. We presented
participants with one of four common metaphors for the teacher-student relationship (identified in a preliminary study) and asked them to
rate the degree to which a series of teacher attributes fit the metaphor. We then used iterated exploratory factor analysis to identify a
small number of dimensions that underlie people’s conceptions of teachers and examined whether the metaphors systematically differed along
these dimensions. We found that teaching metaphors bring to mind distinct, coherent clusters of teacher attributes and different intuitions
about teacher responsibility and power – a finding we replicated in a larger, pre-registered follow-up study using a new set of
participants. This work provides a novel method for mapping the entailments of metaphorical concepts and sets the stage for educational
interventions centered on shifting lay theories of teaching.
Attitudes to accents
Authors: Prikhodkine Alexei
Published: September 2021

This chapter looks at the processes involved in the development of the attitudes to voices. After outlining
the main outcomes – and their social issues – of different research traditions related to language regard studies
(such as language attitude research, language ideology analysis), it goes on to survey the recent findings that focus
on the complexity and the variability of the responses to language varieties. Thereafter, the text discusses to what
extent this focus on complexity conforms to the social constructivist turn in social sciences, namely how current
research deals with non-essentialist assumptions and non-fixity of meanings. Finally, the chapter critically addresses
the agency attributed to social actors in meaning making and examines findings that show the importance of legitimacy
issues to the interpretation of attitudes to accents and make explicit the political dimension in the use of language
resources as well as in the regard on them.
Encountering accented others – and selves – in provincial Japan
Authors: Everhart Edwin K.
Published: September 2021

Who has a regional accent in Japan? Now over a century into the project of language standardization, this
question remains pressing but difficult to answer conclusively. This chapter addresses distinctive characteristics of
the metalinguistics of accent in the Touhoku (northern Honshu) region through local categories, and drawing on
participant observation, it also offers a close reading of moments of indeterminacy in which language users negotiate
the encounter with accent in themselves and in others. Three cases illuminate how the presence or absence of regional
accent is subject to the interactional work of language users, and the identification of accent can be thwarted by a
strategy of non-participation. The chapter concludes by reviewing the impact of accent in language users’ lives.
The pragmatic force of second language accent in education
Authors: Levis John , McCrocklin Shannon
Published: September 2021

Second language (L2) accents are defined by pronunciation features differing from a particular
standard, but listeners perceive more than sound differences when evaluating accents. L2 accents are indexical
to a speaker’s perceived place in an L2 community and convey pragmatic information about a speaker’s identity.
Accent thus impacts the ways learners create identities and manage social roles. Such identity creation may be
especially important in being heard as a valid speaker of the L2, a prerequisite to identity construction and
further language learning. This chapter explores the pragmatic force of L2 accent for learners in educational
settings, by using data collected from language learners and bilinguals and examining participants’ complex
reactions towards accents, and studying the multifaceted goals for their pronunciation.
From I’m the One That I Want to Kim’s Convenience
Authors: Chung Hye Seung
Published: September 2021

In this chapter, I examine the “implicit yellowvoice performances” by Asian American and Asian
Canadian performers as well as the racial implications of such performative acts. In particular, I pay close
attention to Margaret Cho’s “Mom” persona in stand-up comic routines and Ins Choi’s “Appa” (Dad) character in
Kim’s Convenience (played by Paul Sun-Hyun Lee in CBC’s sitcom adaptation of the play).
Ultimately, I argue that while accents play a key role in dramatizing generational and cultural differences
between immigrant parents and their assimilated children, the excessive use of exaggerated accents (faked by
native speakers, members of speech outgroup) contributes to perpetuating “employment discrimination, anxiety
about miscegenation, the necessity of misrecognition, mocking humor…and Orientalist cultural imaginings”
(Ono and Pham, 2009).
Divine intervention
Authors: Villanueva Emily , Ensslin Astrid
Published: September 2021

Videogames often take place in fictional worlds, yet the performed accents of game characters are
real reflections of the language ideologies of a game’s creators and intended audience. This chapter
demonstrates how these ideologies are at play in BioWare’s fantasy role-playing game Dragon Age:
Inquisition (2014), through its linguistic differentiation of two characters, Cassandra and
Leliana. Although largely presented as counter to one another, both are othered from the majority of in-game
characters by way of their accented English. Videogames contain unique, medium-specific affordances; thus,
using multimodal discourse analysis and procedural rhetoric, this chapter examines how Cassandra and Leliana’s
accents construct social and ideological meaning, and how the performative nature of gameplay affects players’
perception of these characters.
In the ear of the beholder
Authors: Setzer Alexandra Besoi , Nicoladis Elena , Baquiran C. Lorelei
Published: September 2021

In the present study, we tested whether a foreign accent activated different stereotypes, depending
on the listener. Here, we explore whether ethnicity of a rater affects the perceived intelligence of a doctor
speaking English with a Chinese accent vs. a doctor speaking English with a standard Canadian accent. As
predicted, the results show an interaction between the ethnicity of the rater and the accent of the doctor:
Chinese Canadians attributed lower intelligence to a doctor speaking with a Chinese accent than with a
standard accent and, conversely, English Canadians perceived both doctors to be highly intelligent – which is
consistent with previous research. We finally discuss how these stereotypes might be related to bias and
interpersonal relations.
From sound to social meaning
Authors: Boudreau Annette , Gasquet-Cyrus Médéric
Published: September 2021

This concluding chapter is written by two francophone researchers who, for years, have tackled the
notion of accents through different angles, different standpoints and above all, different experiences. For
they are not only scholars specialized in the field of accents, but also people whose entire lives are
embedded in accent matters. Whether it is about themselves, people close to them or the subjects encountered
in their surveys and fieldworks, they live in a kind of constant state of ‘participant observation’, wherein
they continuously scrutinize the diversity and complexity of accents under their linguistic, social and
pragmatic aspects. Hence why they were assigned to write the final chapter of this book, which is not a
conclusion nor a synthesis, but a focus on the pragmatic aspects of accents through specific and situated
points of views.
Can a corpus-driven lexical analysis of human and machine translation unveil discourse features that set them apart?
Authors: Frankenberg-Garcia Ana
Published: September 2021

There is still much to learn about the ways in which human and machine translation differ with regard to the contexts that regulate the production and interpretation of discourse. The present study explores whether a corpus-driven lexical analysis of human and machine translation can unveil discourse features that set the two apart. A balanced corpus of source texts aligned with authentic, professional translations and neural machine translations was compiled for the study. Lexical discrepancies in the two translation corpora were then extracted via a corpus-driven keyword analysis, and examined qualitatively through parallel concordances of source texts aligned with human and machine translation. The study shows that keyword analysis not only reiterates known problems of discourse in machine translation such as lexical inconsistency and pronoun resolution, but can also provide valuable insights regarding contextual aspects of translated discourse deserving further research.
Bridging international political economy and public policy and administration research on central banking
Authors: Yagci Mustafa , Bakir Caner
Published: September 2021

Central banking as an avenue of research has been of interest to scholars from International Political Economy (IPE) and Public Policy and Administration (PPA) disciplines. Nevertheless, there is very little dialogue between these two perspectives to bridge macro, meso, micro-level analyses and examine the reciprocal relationship between the global and domestic political economy context and monetary policy conduct. This article investigates the Turkish experience to bridge IPE and PPA scholarship on central banking in emerging economies. In doing so, we adopt an analytic eclectic approach combining multiple structural, institutional, and agential causal explanations with particular reference to the Structure, Institution, and Agency (SIA) theoretical framework. This is because analytic eclecticism complements, speaks to, and selectively incorporates theoretical approaches such as the New Independence Approach (NIA) of IPE and institutional and ideational PPA approaches. Drawing on the empirical context of the historical evolution of the Turkish political economy, we explore domestic and international interactions among micro, meso, and macro levels that shape central banking behavior. Our analysis also reveals how global dynamics are translated into domestic policy choices and how particular ideas influence the policymaking process. The analysis underscores the constraining and enabling influence of international dynamics, politics of ideas on emerging economy central banking, and the essential role individual and organizational agency play in the policymaking process.
Tailoring hot carrier cooling and recombination dynamics of mixed halide perovskite by incorporating Au@CZTS core–shell nanocrystal
Authors: Prodhan Sayan , Chauhan Kamlesh Kumar , Karmakar Manobina , Ghosh Anima , Bhattacharyya Sayan , Datta Prasanta Kumar
Published: September 2021

Organic–inorganic halide perovskite has emerged as the front-runner of absorber materials for highly efficient solar cell in recent years. The incorporation of metallic (Au, Ag) nanoparticles (NPs) within the perovskite contributes to the effective tuning of their optoelectronic properties via enhancing the channels of solar energy transfer and promoting carrier transport. Placing a dielectric shell over the metal NP further enhances the carrier mobility and reduces the carrier recombination in the semiconductor material. Here, we have extensively investigated the effect of the Au@CZTS core–shell nanocrystal (NC) on hot carrier (HC) cooling dynamics and excited carrier recombination dynamics in bulk MAPbI3−X
Cl
X
perovskite using femtosecond transient absorption spectroscopy with a temporal and spectral resolution of 120 fs and 0.8 nm respectively. The HC cooling dynamics indicates the formation of longitudinal optical (LO) phonons within the first 0.6 ps and a delayed conversion of LO phonons to longitudinal acoustic (LA) phonons from 8 ps to 15.9 ps due to the incorporation of the Au@CZTS core–shell NC in bulk perovskite. Further, the investigation of carrier recombination dynamics shows that at a fixed pump fluence of 3.19 μJ cm
−2
the rate constants decrease nearly 1 order of magnitude for (a) Auger recombination (from 1.2 × 10−32 cm6 s−1 to 1.7 × 10−34 cm6 s−1), (b) band-to-band recombination (from 8 × 10−14 cm3 s−1 to 8 × 10−15 cm3 s−1) and (c) trap state recombination (from 5.5 × 108
μs−1 to 5 × 107
μs−1) after the modification of bulk perovskite by Au@CZTS core–shell NC. Delayed conversion of LO phonons to LA phonons confirms the presence of an enhanced ‘hot phonon bottleneck’ effect in modified bulk perovskite. Lowering of the recombination rate constants provides an opportunity for developing high-performance perovskite-based photovoltaics.
Macroscopic-ranged proximity effect in graphite
Authors: Camargo Bruno Cury , Gierłowski Piotr , Kuzmiak Marek , de Jesus Ramon Ferreira , Onufriienko Oleksandr , Szabó Pavol , Kopelevich Yakov
Published: September 2021

We report proximity-induced superconducting features over macroscopic lengths in highly oriented pyrolytic graphite. The phenomenon is triggered when electrical currents are injected in the material through superconducting electrodes, few millimeters apart from each other. Such a large range is anomalous, as proximity-induced features in normal conductors hardly surpass few micrometers. The results can be explained as due to the presence of pre-existing superconductivity in graphite on small, localized regions.
Bursted auricular vagus nerve stimulation alters heart rate variability in healthy subjects
Authors: Széles Jozsef C , Kampusch Stefan , Thürk Florian , Clodi Christian , Thomas Norbert , Fichtenbauer Severin , Schwanzer Christian , Schwarzenberger Sebastian , Neumayer Christoph , Kaniusas Eugenijus
Published: September 2021

Objective. Recent research suggests that percutaneous auricular vagus nerve stimulation (pVNS) beneficially modulates the autonomic nervous system (ANS). Bursted pVNS seems to be efficient for nerve excitation. Bursted pVNS effects on cardiac autonomic modulation are not disclosed yet. Approach. For the first time, the present study evaluates the effect of pVNS on cardiac autonomic modulation in healthy subjects (n = 9) using two distinct bursted stimulation patterns (biphasic and triphasic stimulation) and heart rate variability analysis (HRV). Stimulation was delivered via four needle electrodes in vagally innervated regions of the right auricle. Each of the two bursted stimulation patterns was applied twice in randomized order over four consecutive stimulation sessions per subject. Main results. Bursted pVNS did not change heart rate, blood pressure, and inflammatory parameters in study subjects. pVNS significantly increased the standard deviation of heart inter-beat intervals, from 46.39 ± 10.4 ms to 63.46 ± 22.47 ms (p < 0.05), and the total power of HRV, from 1475.7 ± 616.13 ms2 to 3190.5 ± 2037.0 ms2 (p < 0.05). The high frequency (HF) power, the low frequency (LF) power, and the LF/HF ratio did not change during bursted pVNS. Both stimulation patterns did not show any significant differences in cardiac autonomic modulation. Stimulation intensity to reach a tingling sensation was significantly lower in triphasic compared to biphasic stimulation (p < 0.05). Bursted stimulation was well tolerated. Significance. Bursted pVNS seems to affect cardiac autonomic modulation in healthy subjects, with no difference between biphasic and triphasic stimulation, the latter requiring lower stimulation intensities. These findings foster implementation of more efficient pVNS stimulation.
Actuator placement optimization in an active lattice structure using generalized pattern search and verification
Authors: Du Pasquier Cosima , Shea Kristina
Published: September 2021

Shape morphing structures are actively used in the aerospace and automotive industry. By adapting their shape to a stimulus such as heat, light, or pressure, a design can be optimized to achieve a broader band of functionality over its lifetime. The quality of a structure with respect to shape-morphing can be assessed using five criteria: weight, load-carrying capacity, energy consumption, accuracy of the controlled deformation, and the range and number of achievable target shapes. This work focuses on the use of lightweight and stiff active lattice structures, where the layout of actuators within the structure determines the final deformation. It uses a statically and kinematically determinate Kagome lattice pattern that has been shown to deform the most accurately with the least energy. The use of a determinate structure justifies the implementation of a simplified deformation model. The deformation resulting from a given actuator layout can be expressed as a linear combination of the deformation of individual actuators, which are all computed in a pre-processing step and expressed with an influence matrix. The actuator layout is thus optimized for several target shapes. The linear combination model is shown to replicate FEM simulations with an average of 94.8% accuracy for all target shapes. The actuator layouts in one-level lattices are tested using a novel design for a 3D printed modular Kagome pneumatic lattice structure. The experimental results replicate the target shapes with an average accuracy of 79.9%. The resulting actuator layouts are shown to form more target shapes with a similar deformation range as similar publications.
Low-thermal-budget Au-free ohmic contact to an ultrathin barrier AlGaN/GaN heterostructure utilizing a micro-patterned ohmic recess
Authors: Shi Wen , Huang Sen , Wang Xinhua , Jiang Qimeng , Yao Yixu , Bi Lan , Li Yuchen , Deng Kexin , Fan Jie , Yin Haibo , Wei Ke , Li Yankui , Shi Jingyuan , Jiang Haojie , Li Junfeng , Liu Xinyu
Published: September 2021

A pre-ohmic micro-patterned recess process, is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier (UTB) AlGaN/GaN heterostructure, featuring a significantly reduced ohmic contact resistivity of 0.56 Ω·mm at an alloy temperature of 550 °C. The sheet resistances increase with the temperature following a power law with the index of +2.58, while the specific contact resistivity decreases with the temperature. The contact mechanism can be well described by thermionic field emission (TFE). The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52 × 1018 cm−3, which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer. A good correlation between ohmic transfer length and the micro-pattern size is revealed, though in-depth investigation is needed. A preliminary CMOS-process-compatible metal–insulator–semiconductor high-mobility transistor (MIS-HEMT) was fabricated with the proposed Au-free ohmic contact technique.
Analysis on the Conductivity of Graphene-based Composite Material
Authors: Yang Dalei
Published: September 2021

Electric energy is the main energy source in production and life. How to make efficient transmission and utilization of electric energy is a problem that requires long-term research. Graphene, as a material with a single-layer two-dimensional honeycomb lattice carbon chain structure, has good electrical conductivity. Its composite with conductive polymer or inorganic metal materials can effectively improve its electrical conductivity and obtain more outstanding electrochemical performance. In order to understand the application of graphene’s electrical conductivity in life in more detail, this article first reviews the electrical properties of graphene, and then reviews and analyzes the research progress of graphene polymer electrical conductivity based on different composite materials and processing methods. The author also points out that the biggest problem facing graphene composites now is that the expensive price of graphene nanosheets and its unavailableness in large-scale applications and industrial production, as well as proposes that the future of graphene composites is still through scientific research in a short period of time. Continuously improving its electrical conductivity is necessary, yet the long-term strategic goal should be reducing the cost of industrialized production of graphene products and find the preparation conditions of graphene composite materials that are more suitable for industrial production.
Simulation Analysis of Thermoplastic Composites on Suspension Brackets of Electric Commercial Vehicles
Authors: Zhao Haijun , Wang Haixia , Zhai Naibin , Li Hongliang , Wang Zhiqiang , Wang Feng
Published: September 2021

Lightweight is more important in electric commercial vehicles, the static simulation analysis is first carried out on the suspension system bracket using the material of steel under three working conditions in this paper. Taking the suspension system bracket connection plate as an example, the bracket connecting plate model of the suspension system is established with thermoplastic composite materials, which is nine-layer three-dimensional model. The pre-processing, solving and post-processing procedures of the stress analysis of the part are introduced, and the stress distribution of different layers is obtained. Results show that the maximum stress of the steel bracket of the suspension system under three working conditions of triple gravity, acceleration of gravity adding steering inertia, acceleration of gravity adding braking inertia are 189.22, 92.48, and 156.9Mpa for steel, which are all less than the ultimate stress of 235Mpa. The maximum stress of each layer of the thermoplastic composite connecting plate meets the design requirements. In the case of the same ply angle, the bottom layer will bear less and less stress, the base layer will bear very little stress, and the main stress will be borne by the reinforcing material, support is provided for the application of thermoplastic composite materials on automobile chassis.
Application of Ecological Technology of Concrete Retaining Wall in Urban Dyke
Authors: Yuan Yimei , Liu Kun
Published: September 2021

Traditional concrete and mortar-masonry retaining walls are mature, safe and reliable, widely used in urban river embankment, and play a great role in disaster prevention and mitigation in towns. However, such retaining walls lack of ecological characteristics. In order to give the traditional concrete and mortar-masonry retaining walls ecological characteristics and provide conditions for the unfortunate people who fell into the water to rescue themselves and go ashore, two traditional retaining wall ecological technologies were invented, which are suitable for new retaining walls and existing retaining walls. When the new retaining wall is built, the slope ratio of the wall should be appropriately slowed down and several rows of planting grooves should be arranged. For the retaining wall that has been built, the planting groove is anchored on the wall. Landscape plants are selected and planted in the planting groove, and automatic irrigation system is arranged according to the needs. The engineering application shows that applying these two technologies to river improvement projects at the same time can form a full coverage of ecological beauty on the water-side wall of the traditional retaining wall. People who fall into the water can climb on the planting trough and wait for rescue, or climb along the planting trough to reach the goal of harmonious coexistence between people and water.
Shear properties of studs in alkali-activated ultra-high performance concrete
Authors: Gao Yanpeng , Wei Dong , Gao Zhao
Published: September 2021

With the wide application of ultra-high performance concrete in strengthening orthotropic steel bridge deck, the fatigue damage of steel bridge deck and the cracking of pavement layer are effectively solved. More green and environmentally friendly alkali-activated ultra-high performance concrete is also proposed. The finite element analysis method was used to study the shear performance of different diameter and length of the stud in alkali-activated UHPC. The results show that the diameter of the stud has the greatest influence on the shear bearing capacity of the stud, and the length-diameter ratio has a certain influence on the slip.