bluuebunny/crossref_metadata_2025 huggingface dataset:
The Language Environment at Home of Children With (a Suspicion of) a Developmental Language Disorder and Relations With Standardized Language Measures
Authors: Blom Elma , Fikkert Paula , Scheper Annette , van Witteloostuijn Merel , van Alphen Petra
Published: July 2023

Purpose:

This study compares the home language environments of children with (a suspicion of) developmental language disorder (DLD) with that of children with typical development (TD). It does so by adopting new technology that automatically provides metrics about children's language environment (Language ENvironment Analysis [LENA]). In addition, relationships between LENA metrics and standardized language tests are explored in the DLD group.

Method:

Ninety-nine 2- to 4-year-old toddlers participated: 59 with (a suspicion of) DLD and 40 with TD. LENA metrics on adult word count, conversational turn count, and child vocalization count were obtained. For all children, data on parental education and multilingualism were available. In the DLD group, data were collected on receptive and expressive vocabulary and grammar, and on nonverbal intelligence, using standardized tests.

Results:

We found lower adult word count, conversational turn count, and child vocalization count in the DLD group, independent of multilingualism but not of parental education. In the DLD group, receptive vocabulary was related to conversational turn count and child vocalization count, but not to adult word count. Expressive vocabulary, receptive grammar, and expressive grammar were not related to LENA metrics.

Conclusions:

Toddlers with (a suspicion of) DLD vocalize less at home than children with TD. They also hear fewer adult words and experience fewer conversational turns. Children with DLD's language outcomes are to a limited extent related to language environment at home. Conversational turns and child vocalizations are in this respect more important than adult words, in line with findings for TD populations.
HVDC grids stability enhancement through the integration of battery energy storage systems
Authors: Azizi Neda , Moradi Hassan , Rouzbehi Kumars , Mohammadi Fazel
Published: July 2023

In high voltage direct current (HVDC) grids, the reference values of power controllers are normally adjusted based on the DC‐link voltage as the DC voltage is regulated by the droop controllers. As a matter of fact, except for the DC slack bus, there is a trade‐off between power‐sharing and voltage regulation of all the remaining HVDC buses. The main issue with this control strategy is that in case of contingencies, significant voltage and power oscillations throughout HVDC grids can be expected. To address such issues, the integration of a battery energy storage system into HVDC grids through a multi‐port DC/DC power converter is investigated in this paper. The DC/DC converter used in this paper consists of three ports: (1) two ports are connected in cascade with the intended DC transmission line, formerly named cascaded power flow controller, and (2) the third port is for the integration of the battery energy storage system to form a multi‐functional device. Therefore, the proposed framework can potentially achieve small‐signal stability enhancement and regulate/adjust the power throughout the HVDC grids.
Revealing the structure of the lensed quasar Q 0957+561
Authors: Fian C. , Muñoz J. A. , Mediavilla E. , Jiménez-Vicente J. , Motta V. , Chelouche D. , Wurzer A. , Hanslmeier A. , Rojas K.
Published: July 2023

Aims. Our aim is to examine the size, kinematics, and geometry of the broad-line region (BLR) in the double-lensed quasar Q 0957+561 by analyzing the impact of microlensing on various rest-frame ultraviolet broad-emission lines (BELs).

Methods. We explore the influence of intrinsic variability and microlensing on the C IV, C III], and Mg II emission lines through multiple spectroscopic observations taken between April 1999 and January 2017. By utilizing the line cores as a reference for no microlensing and correcting for the long time delay between the images, we estimate the sizes of the regions emitting the broad-line wings using a Bayesian approach.

Results. Our study of the microlensing amplitudes between the lensed images of the quasar Q 0957+561 reveals differing sizes of the regions emitting the three prominent BELs C IV, C III], and Mg II. The strength of the differential microlensing indicates that the high-ionization line C IV arises from a compact inner region of the BLR with a half-light radius of R1/2 ≳ 16.0 lt-days, which represents a lower limit on the overall size of the BLR and is comparable to the size of the region emitting the r-band continuum in this system. A somewhat larger size of R1/2 ≳ 44 lt-days is obtained for the semi-forbidden line C III]. Microlensing has a weak impact on the lower-ionization line Mg II, which is emitted from a region with a half-light radius of R1/2 ≳ 50 lt-days. These findings suggest that the BEL regions may have distinct geometries and kinematics, with the more extended ones being spherically symmetric, and the most compact ones being nonspherical, with motions likely confined to a plane.
Examining the interrelation behavior of distance metrics for head-related transfer function evaluation: a case study
Authors: Doma Shaima’a , Brožová Natálie , Fels Janina
Published: July 2023

The comparison of head-related transfer functions (HRTFs), e.g., for validating different acquisition methods, requires a meaningful way of quantifying HRTF differences – a problem to which literature offers no standardized approach. This impedes the comparability and interpretability of studies. The present work therefore addresses the lack of proper understanding of the behavior of commonly used distance metrics by applying seven metrics to individually measured and approximated HRTF datasets. Covering a variety of spectral deviations, we perform both intra-individual comparisons (contrasting different levels of spectral detail for the same individual) and inter-individual comparisons (assessing metric reactions to non-individual cue differences). The metrics exhibit selective reactions to distinct spectral alterations. Particularly, the results demonstrate that spectrally localized errors go undetected by five out of seven metrics. Further analysis emphasizes inconsistencies in metric correlation patterns. These observations highlight the need for a multi-dimensional metric, capturing various types of HRTF differences for a proper assessment of errors.
Retrofit design strategies for educational building through shading and glazing modification
Authors: Sebayang Silvia , Alkadri Miktha Farid , Chairunnisa Intan , Dewi Ova Candra
Published: July 2023

Passive design strategies play a significant part in improving the performance of retrofitting buildings. This especially applies to educational buildings that demand a high quantity of energy, not only due to various types of rooms and occupants but also operational needs of space regarding heating and cooling. Besides, the energy performance of the buildings will gradually decrease due to natural factors, such as aging and extreme weather conditions. Through retrofit design strategies, this study explores various scenarios on educational building facades by modifying shading and glazing properties. In this regard, several scenarios are proposed such as an addition of vertical fins, changing of glazing properties, and a combination of both. This study results in, first, the reduction of the Overall Thermal Transfer Value (OTTV) by 6,04 W/m2 and second, the reduction of indoor temperature by 0,835°C from the existing to a proposed combination scenario. This study ultimately enables the architects in determining the optimum retrofitted facade strategy for educational buildings in the tropical climate.
Mean-field limit of a hybrid system for multi-lane multi-class traffic
Authors: Gong Xiaoqian , Piccoli Benedetto , Visconti Giuseppe
Published: July 2023

This article aims to study coupled mean-field equation and ODEs with discrete events motivated by vehicular traffic flow. Precisely, multi-lane traffic flow in presence of human-driven and autonomous vehicles is considered, with autonomous vehicles possibly influenced by external policymakers. First, a finite-dimensional hybrid system is developed based on the continuous Bando-Follow-the-Leader dynamics coupled with discrete events due to lane-change maneuvers. Then the mean-field limit of the finite-dimensional hybrid system is rigorously derived for the dynamics of the human-driven vehicles. The microscopic lane-change maneuvers of the human-driven vehicles generate a source term for the mean-field PDE. This leads to an infinite-dimensional hybrid system described by coupled Vlasov-type PDE, ODEs, and discrete events.
Controllability of surface gravity waves and the sloshing problem
Authors: Fontelos M.A. , López-Ríos J.
Published: July 2023

We study the problem of controlling the free surface for a two dimensional solid container in the context of the gravity waves and the sloshing problem. By using conformal maps and the Dirichlet–Neumann operator, the problem is formulated as a second order evolutionary equation on the free surface involving a self-adjoint operator. We present then the appropriate Sobolev spaces where having solutions for the system and study the exact controllability through an observability inequality for the adjoint problem.
Control Sets of Linear Control Systems on ℝ2. The Complex Case
Authors: Ayala Víctor , Da Silva Adriano , Mamani Erik
Published: July 2023

This paper explicitly computes the unique control set D with the non-empty interior of a linear control system on ℝ2, when the associated matrix has complex eigenvalues. It turns out that the closure of D coincides with the region delimited by a computable periodic orbit 𝒪 of the system.
New second-order optimality conditions in sub-riemannian geometry
Authors: Jóźwikowski Michał
Published: July 2023

We study the geometry of the second-order expansion of the extended end-point map for the sub-Riemannian geodesic problem. Translating the geometric reality into equations we derive new second-order necessary optimality conditions in sub-Riemannian Geometry. In particular, we find an ODE for velocity of an abnormal sub-Riemannian geodesics. It allows to divide abnormal minimizers into two classes, which we propose to call 2-normal and 2-abnormal extremals. In the 2-normal case the above ODE completely determines the velocity of a curve, while in the 2-abnormal case the velocity is undetermined at some, or at all points. With some enhancement of the presented results it should be possible to prove the regularity of all 2-normal extremals (the 2-abnormal case seems to require study of higher-order conditions) thus making a step towards solving the problem of smoothness of sub-Riemannian abnormal geodesics. As a by-product we present a new derivation of Goh conditions. We also prove that the assumptions weaker than these used in [Boarotto, Monti, Palmurella, 2020] to derive third-order Goh conditions, imply piece-wise-C2 regularity of an abnormal extremal.

Marty me i Zuzi
Equilibrium pricing of securities in the co-presence of cooperative and non-cooperative populations
Authors: Fujii Masaaki
Published: July 2023

In this work, we develop an equilibrium model for price formation of securities in a market composed of two populations of different types: the first one consists of cooperative agents, while the other one consists of non-cooperative agents. The trading of every cooperative member is assumed to be coordinated by a central planner. In the large population limit, the problem for the central planner is shown to be a conditional extended mean-field control. In addition to the convexity assumptions, if the relative size of the cooperative population is small enough, then we are able to show the existence of a unique equilibrium for both the finite-agent and the mean-field models. The strong convergence to the mean-field model is also proved under the same conditions.
A general maximum principle for progressive optimal control of partially observed mean-field stochastic system with Markov chain
Authors: Chen Tian , Jia Yunxiao
Published: July 2023

In this paper, we study an optimal control problem of partially observed mean-field type stochastic control system with Markov chain in progressive structure. The control variable is allowed to enter the diffusion term of the state process and the drift term of the observation process. The control domain need not be convex. In our model, the cost functional and the observation are also of mean-field type. By virtue of a special spike variation, the related stochastic maximum principle has been obtained. The stochastic maximum principle in progressive structure is essentially different from the classical case.
Turnpike properties of optimal boundary control problems with random linear hyperbolic systems
Authors: Gugat Martin , Herty Michael
Published: July 2023

In many applications, in systems that are governed by linear hyperbolic partial differential equations some of the problem parameters are uncertain. If information about the probability distribution of the parametric uncertainty, distribution is available, the uncertain state of the system can be described using an intrinsic formulation through a polynomial chaos expansion. This allows to obtain solutions for optimal boundary control problems with random parameters. We show that similar to the deterministic case, a turnpike result holds in the sense that for large time horizons the optimal states for dynamic optimal control problems on a substantial part of the time interval approaches the optimal states for the corresponding uncertain static optimal control problem. We show turnpike results both for the full uncertain system as well as for a generalized polynomial chaos approximation.
Der Berliner Psychiater Eugen Wauschkuhn (1883–1948)
Authors: Suwa Beato
Published: July 2023

Der biografisch kaum beachtete Berliner Psychiater Eugen Wauschkuhn ist heute vor allem aufgrund eines im Jahre 1922 verfassten Artikels bekannt, in dem er sich sehr deutlich gegen die von Alfred Hoche propagierte „Vernichtung lebensunwerten Lebens“ positioniert. Das ist bemerkenswert, da er verschiedene spätere Entwicklungen im nationalsozialistischen Staat („Euthanasie“) teilweise detailliert voraussieht und vor solchen möglichen Folgen warnt. Archiv- und Literaturrecherchen sowie ein neu aufgefundener, längerer Brief von Eugen Wauschkuhn mit Datum vom 22.04.1921 zeigen einige neue Hintergrundinformationen auf und ergänzen die biografischen Angaben zu seiner Person.
Serum ADAMTS-9 Level in Newborn Babies with Congenital Heart Disease
Authors: Becerir Cem , Tayman Cüneyt , Kurt Abdullah , Çakır Ufuk , Koyuncu İsmail , Ceran Burak , Toprak Kenan , Kızılgün Murat
Published: July 2023

Objective A Disintegrin and Metalloproteinase with Thrombospondin-9 (ADAMTS-9), one of the ADAMTS enzymes, is expressed in all fetal tissues, unlike other ADAMTS enzymes, and is thus thought to play a role in fetal development. In this context, the objective of this study is to investigate the relationship between ADAMTS-9 activity and the development of congenital heart diseases (CHD) with a view to using ADAMTS-9 level as a biomarker for CHDs.

Study Design Newborns diagnosed with CHD and healthy newborns were included in the study as the CHD and control groups, respectively. Gestational age, maternal age, and mode of delivery information pertaining to the mothers and Apgar score and birthweight information pertaining to the newborns were recorded. Blood samples were taken from all newborns to determine their ADAMTS-9 levels in the first 24 hours of life.

Results Fifty-eight newborns with CHD and 46 healthy newborns were included in the study. Median ADAMTS-9 levels were 46.57 (interquartile range [IQR]: 33.31 [min: 26.92, max: 124.25]) and 23.36 (IQR: 5.48 [min: 11.7, max: 37.71]) ng/mL in the CHD and control groups, respectively. ADAMTS-9 levels in the CHD group were statistically significantly higher than in the control group (p = 0.000). ADAMTS-9 levels of the CHD and control groups were analyzed by the receiver operating characteristics curve. The area under the curve value for ADAMTS-9 levels of >27.86 ng/mL as the cut-off value for predicting the development of CHD in newborns was 0.836 (95% confidence interval [CI]: 0.753–0.900, p = 0.0001). ADAMTS-9 levels of >27.86 ng/mL were determined to predict the development of CHD in newborns with a sensitivity of 77.78% (95% CI: 65.5–87.38) and a specificity of 84.78% (95% CI: 71.1–93.60).

Conclusion In conclusion, it was found that the serum ADAMTS-9 levels were significantly higher in newborns with CHD than in healthy newborns. In parallel, ADAMTS-9 levels above a certain cut-off value were associated with CHD.

Key Points
Advanced halide materials provide next-generation anti-counterfeiting
Authors: Johnson-Groh Mara
Published: July 2023

Novel copper-based halide composite with triple mode emissions could be used in bank notes to make them harder to counterfeit.
The Marchenko method to solve the general system of derivative nonlinear Schrödinger equations
Authors: Aktosun Tuncay , Ercan Ramazan , Unlu Mehmet
Published: July 2023

A system of linear integral equations is presented, which is the analog of the system of Marchenko integral equations, to solve the inverse scattering problem for the linear system associated with the DNLS (derivative nonlinear Schrödinger) equations. The corresponding direct and inverse scattering problems are analyzed, and the recovery of the potentials and the Jost solutions from the solution to the Marchenko system is described. When the reflection coefficients are zero, some explicit solution formulas are provided for the potentials and the Jost solutions in terms of a pair of constant matrix triplets representing the bound-state information for any number of bound states and any multiplicities. In the reduced case, when the two potentials in the linear system are related to each other through complex conjugation, the corresponding reduced Marchenko integral equation is obtained. The solution to the DNLS equation is obtained from the solution to the reduced Marchenko integral equation. The theory presented is illustrated with some explicit examples.
Cylindrical Acoustic Gas Thermometry
Authors: Xing Li , Feng Xiao-Juan , Si Ming-Hao , Zhang Jin-Tao , Lin Hong , Gillis Keith A. , Moldover Michael R.
Published: July 2023

We review recent determinations of the Boltzmann constant kB and the differences T − T90 that used cylindrical acoustic gas thermometry (c-AGT). These determinations measured the acoustic resonance frequencies of argon gas enclosed by metal-walled, cylindrical cavities. (Here, T is the thermodynamic temperature and T90 is the temperature measured on the International Temperature Scale of 1990, ITS-90.) In the range 234–303 K, the standard uncertainty of c-AGT ranges from 1.9 × 10−6T to 2.6 × 10−6T. This uncertainty is much smaller than the errors in ITS-90; therefore, c-AGT can help improve ITS-90. Moreover, we are extending c-AGT up to 1358 K. With increasing temperatures, c-AGT becomes advantageous relative to AGT based on quasi-spherical cavities because long cylindrical cavities (1) naturally fit into cylindrical heat pipes or multi-shelled thermostats; (2) provide the immersion required by transfer temperature standards, such as long-stemmed platinum resistance thermometers; and (3) have more useful, low-frequency acoustic resonances. In preparation for high-temperature c-AGT, we identified suitable materials for fabricating cylindrical cavities and we developed techniques for measuring acoustic resonance frequencies using sources and detectors outside the high-temperature thermostat. We also considered alternative test gases and optimal dimensions of cavities.
Pump wavelength-dependent terahertz spin-to-charge conversion in CoFeB/MgO Rashba interface
Authors: Levchuk Artem , Juvé Vincent , Otomalo Tadele Orbula , Chirac Théophile , Rousseau Olivier , Solignac Aurélie , Vaudel Gwenaëlle , Ruello Pascal , Chauleau Jean-Yves , Viret Michel
Published: July 2023

Spin/charge interconversion mechanisms provide an essential handle to generate and detect spin currents. Their applications at different timescales are critical in spintronics since they cover a technologically relevant broadband spectrum. While the inverse spin Hall effect is known to be robust from quasi-static to sub-picosecond timescales, the conversion efficiency evolution of the inverse Edelstein effect has not been addressed yet. In this work, we report that while the quasi-static response of the inverse Edelstein effect can be comparable to that of the most efficient inverse spin Hall systems, a drastic drop of efficiency is observed in the terahertz (THz) regime. This behavior at the sub-picosecond timescale is qualitatively understood from the dependence of the inverse Edelstein effect on the energy distribution of spin-carrier entities, which is different between thermalized carriers in the quasi-static regime and hot carriers generated by light pulses. This finding is supported by the pump-laser wavelength dependence in the THz regime for the inverse Edelstein effect, which offers a promising route for tunability of spintronic devices.
Effect on drag–thrust transition for flapping airfoil with chordwise flexibility
Authors: Sharma Vikas , Dutta Sushanta
Published: July 2023

The objective of the current study is to leverage hereditary flexibility to enhance an airfoil's aerodynamic performance. The aim is to understand the effect of drag reduction by imparting chordwise flexibility and thereby increasing thrust generation. The study is done on NACA0015 airfoil to examine the effects of chordwise foil flexibility on the dynamical features of flapping-based propulsion. The experimental work considers pitching oscillations of the rigid and flexible airfoil at three pitching amplitudes and three frequencies in a subsonic wind tunnel for the Reynolds number (Re) in the range 1.2–5.1 × 103. Flow visualization, a hotwire anemometer, and particle image velocimetry are used to study the flow field. The findings demonstrate that the foil flexibility alters force parameters and efficiently increases thrust generation. For a higher value of Strouhal number (StD), the effect is more pronounced. The minimum drag coefficient ratio (Cdr) for the flexible foil is −3.17 compared to −1.55 for the case of a rigid foil. The result suggests that flexibility could impart twice the propulsion in the flapping range studied. The drag–thrust transition occurs in the 2P wake regime for the low oscillation frequency. The results show that the undulating flexible foil enhances the flow around the trailing edge, which causes local acceleration in the fluid. The vortex is shed closer to the leading edge for the flexible case because of the large flap deformation. A region of a wider and stronger envelope of velocity jet is formed behind the airfoil for the flexible case. The excess momentum enables the flexible foil to generate higher thrust. The result suggests that jet deflection and meandering are suppressed in the flexible case compared to the rigid case. The experimental results would assist in designing flexible wings with higher thrust-generation capacity for improved propulsion.
Effect of laser power density on the formation of slip in single crystal germanium
Authors: Sha YinChuan , Li ZeWen , Jia ZhiChao , Pan YunXiang , Ni XiaoWu
Published: July 2023

Numerical calculations and experimental approaches are used to examine the slip characteristics of 1064 nm laser ablated single crystal germanium. The ablation and cooling processes are used to investigate the influence of laser power density on the creation of the slip process. A 1064 nm continuous laser and a nanosecond laser were used to ablate single-crystal germanium samples, and the damage to the surface was seen using an optical microscope. The results demonstrate that raising the laser power density to 107 W/cm2 efficiently suppresses slip production during laser processing.
Defect level in κ-Ga2O3 revealed by thermal admittance spectroscopy
Authors: Langørgen Amanda , Kalmann Frodason Ymir , Karsthof Robert , von Wenckstern Holger , Thue Jensen Ingvild Julie , Vines Lasse , Grundmann Marius
Published: July 2023

Defects in pulsed-laser deposition grown have been investigated using thermal admittance spectroscopy and secondary ion mass spectrometry (SIMS). A film was grown on either a tin-doped indium oxide or an aluminum-doped zinc oxide buffer layer on a sapphire substrate functioning as back contact layer in vertical diode structures. In both sample types, a distinct signature in the capacitance signal was observed in the temperature range of 150–260 K. The corresponding defect charge-state transition level, labeled , was found to exhibit an activation energy of 0.21 eV. Potential candidates for the level were investigated using a combination of SIMS and hybrid-functional calculations. SIMS revealed the main impurities in the sample to be tin, silicon, and iron. The hybrid-functional calculations predict the acceptor levels of substitutional iron to lie 0.7–1.2 eV below the conduction band minimum depending on Ga-site, making an unlikely candidate for the level. Furthermore, Si as well as Sn substituting on the sixfold coordinated Ga2 site and the fivefold coordinated Ga3 and Ga4 sites are all shallow donors in -, similar to that of -. Sn substituting on the fourfold Ga1 site is, however, predicted to have levels in the bandgap at 0.15 and 0.24 eV below the conduction band minimum, in accordance with the extracted activation energy for . Thus, we tentatively assign as the origin of the level.
On the statistical theory of self-gravitating collisionless dark matter flow
Authors: Xu Zhijie (Jay)
Published: July 2023

Dark matter, if it exists, accounts for five times as much as the ordinary baryonic matter. Compared to hydrodynamic turbulence, the flow of dark matter might possess the widest presence in our universe. This paper presents a statistical theory for the flow of dark matter that is compared with N-body simulations. By contrast to hydrodynamics of normal fluids, dark matter flow is self-gravitating, long-range, and collisionless with a scale-dependent flow behavior. The peculiar velocity field is of constant divergence nature on small scale and irrotational on large scale. The statistical measures, i.e., correlation, structure, dispersion, and spectrum functions, are modeled on both small and large scales, respectively. Kinematic relations between statistical measures are fully developed for incompressible, constant divergence, and irrotational flow. Incompressible and constant divergence flow share the same kinematic relations for even order correlations. The limiting correlation of velocity ρL=1/2 on the smallest scale (r = 0) is a unique feature of collisionless flow (ρL=1 for incompressible flow). On large scale, transverse velocity correlation has an exponential form T2∝e−r/r2 with a constant comoving scale r2=21.3 Mpc/h that may be related to the horizon size at matter–radiation equality. All other correlation, structure, dispersion, and spectrum functions for velocity, density, and potential fields are derived analytically from kinematic relations for irrotational flow. On small scale, longitudinal structure function follows one-fourth law of S2l∝r1/4. All other statistical measures can be obtained from kinematic relations for constant divergence flow. Vorticity is negatively correlated for scale r between 1 and 7 Mpc/h. Divergence is negatively correlated for r > 30 Mpc/h that leads to a negative density correlation.
Enhanced confinement induced by pellet injection in the stellarator TJ-II
Authors: García-Cortés I. , McCarthy K. J. , Estrada T. , Tribaldos V. , Medina-Roque D. , van Milligen B. , Ascasíbar E. , Carrasco R. , Chmyga A. A. , García R. , Hernández-Sánchez J. , Hidalgo C. , Kozachek A. S. , Medina F. , Ochando M. A. , de Pablos J. L. , Panadero N. , Pastor I.
Published: July 2023

Enhanced confinement is observed in neutral beam injector (NBI)-heated hydrogen discharges made in the stellarator TJ-II after the injection of a single cryogenic fuel pellet into the plasma core. In addition to the expected increase in electron density, ne, in the core after pellet injection (PI), the plasma diamagnetic energy content is seen to rise, with respect to similar discharges without PI, by up to 40%. Furthermore, the energy confinement time, τEdiag, as determined using a diamagnetic loop, is enhanced when compared to predictions obtained using the International Stellarator Scaling law [H. Yamada et al., Nucl. Fusion 45, 1684 (2005)] and the triple product, ne · Ti · τEdiag, exhibits a clear bifurcation point toward an improved confinement branch as compared to the branch product predicted by this scaling law. In general, once such a pellet-induced enhanced confinement (PiEC) phase has been established, it is characterized by steepened radial density gradients, by more negative plasma potential in the core, more negative radial electric fields, Er, across a broad plasma region, as well as by reductions in density and plasma potential fluctuations in the density gradient region. In addition, experimental observations show increased peaking of core radiation losses, this pointing to edge/core plasma decoupling. In parallel, neoclassical simulations of reference and PiEC plasmas predict increased particle and energy confinement times during a PiEC phase together with a more negative Er profile. Qualitative rather than quantitative agreement with experimental parameters is found, indicating that turbulence seems to play a significant role here. In summary, single cryogenic pellet injection facilitates the achievement of an enhanced operational regime that was previously not observed in NBI-heated discharges of the TJ-II.
Review and perspective on acoustic metamaterials: From fundamentals to applications
Authors: Zhang Jiangyi , Hu Bo , Wang Shibo
Published: July 2023

In the past two decades, the research on acoustic metamaterials has flourished, which is also benefited from the development of additive manufacturing technology. The exotic physical phenomena and principles exhibited by acoustic metamaterials have attracted widespread attention from academia and engineering communities, which can be applied to noise reduction and acoustic nondestructive testing in industrial; invisible cloaking and camouflage in the military; medical ultrasound imaging in national health; acoustic stealth in defense security, detection in the ocean, communication, and other fields, i.e., acoustic metamaterials have important scientific research value and broad application prospects. This review summarizes the history and research status of acoustic metamaterials, focusing on the main research progress of metamaterials in nonlinear acoustic and acoustic coatings fields, including the research on acoustic coatings with cavities of our group. Finally, the future development direction of acoustic metamaterials is prospected, and the difficulties and challenges faced by the actual engineering of acoustic metamaterials are discussed, such as difficulties in mass production, hydrostatic pressure resistant property, omnidirectional wave control, high production costs, and so on.
Perspectives and opportunities with multisubband plasmonics
Authors: Montes Bajo M. , Chauveau J.-M. , Vasanelli A. , Delteil A. , Todorov Y. , Sirtori C. , Hierro A.
Published: July 2023

In highly doped semiconductor quantum wells (QWs), electrons populate various energy states from different subbands and, therefore, several optical intersubband transitions (ISBTs) can occur simultaneously. Coulomb coupling between these ISBTs gathers the strength of all the individual transitions and concentrates all the oscillator strength in a single collective excitation: the multisubband plasmon (MSP). MSPs are an excellent platform for the study of collective and exotic effects in semiconductors and for the demonstration of novel device concepts. Indeed, the high electronic densities involved in the collective excitation greatly enhance the coupling strength and enable the ultra-strong coupling regime between MSPs and either optical modes in a cavity or phonons in the semiconductor. In this Perspectives paper, after addressing the basic physics of MSPs and the state of the art, we outline the most promising paths for the research community in this topic from the point of view of basic physics, material platforms, and applications of MSPs.
Accurate and wide-range measurement of thermal conductivity of semiconductor materials by laser-excited Raman spectroscopy
Authors: An Ruihua , Zhao Jinyan , Yang Jun , Zhai Shijie , Dai Liyan , Wang Qiang , Li Jie , Hu Wenbo , Sun Guipeng , Fan Yang , Wu Shengli , Niu Gang
Published: July 2023

The accurate measurement of the thermal conductivity in a wide range of semiconductors is of great importance for applications like power electronic devices, which is, however, quite challenging. Current measurement methods suffer from limited measurement range, non-accuracy, complexity, etc. We report in this work an effective in situ method for thermal conductivity measurement based on laser-excited Raman spectroscopy, which has the advantages of non-contact, non-destructive, facile preparation, easy operation, and the capability of a large measurement range. The critical relationship parameters correlating Raman peak shifts and temperature change can be extracted by monitoring and fitting the Raman peak movement at different temperatures. Here, the laser with the micrometer scale spot serves as a Raman scattering source and a heat source for the samples. The thermal conductivity of Si, SiC, polycrystalline diamond, and single crystalline diamond at room temperature was determined to be 140.2 ± 14.4, 414.7 ± 26.2, 1372.3 ± 229.0, and 1734.9 ± 280.6 W/(m K), respectively, which are in good agreement with the theoretical prediction. The temperature distribution of the samples was simulated by the finite element method, which confirms the experimental data. These results highlight the feasibility, reliability, and versatility of Raman spectroscopy for measuring semiconductor materials, particularly those with high thermal conductivity. This is of great interest for exploring semiconductor physics and practical applications like power electronic devices.
Square-package arrays for efficient trapping of terahertz waves
Authors: Zhu Xiaoqing , Wang Bo
Published: July 2023

In this paper, a broadband metamaterial absorber consisting of the doped silicon substrate and the square array of doped silicon covered by a SU-8 layer is presented. The target structure achieves an average absorption of 94.42% in the studied frequency range (0.5–8 THz). In particular, the structure exceeds 90% absorption in the frequency range of 1.44–8 THz, which is a significant increase in bandwidth relative to reported devices of the same type. Next, the near-perfect absorption of the target structure is verified by the impedance matching principle. Furthermore, through the analysis of the electric field distribution inside the structure, the physical mechanism of its broadband absorption is investigated and explained. Finally, the impact of fluctuations in the incident angle, polarization angle, and structural parameters on the absorption efficiency is examined at length. The analysis shows that the structure has characteristics, such as polarization insensitivity, wide-angle absorption, and good process tolerance. The proposed structure is advantageous for applications in THz shielding, cloaking, sensing, and energy harvesting.
Theoretical investigation of the triggering of neoclassical tearing modes by transient resonant magnetic perturbations in NSTX
Authors: Fitzpatrick R. , Maingi Rajesh , Park Jong-Kyu , Sabbagh Steve
Published: July 2023

The extended perturbed equilibrium code asymptotic matching code is used to simulate the triggering of n = 1 neoclassical tearing modes (NTMs) by a pulsed, rotating, n = 1, resonant magnetic perturbation (RMP) in two example NSTX discharges. Although the two discharges are significantly different from one another, the results of the two sets of simulations are quite similar. The critical n = 1 RMP pulse amplitude required to trigger an n = 1 NTM is minimized when the RMP pulse rotation frequency matches the linear natural frequency of an n = 1 tearing mode, resonant within the plasma, that is metastable to an NTM. However, if there is a frequency mismatch, then the seed magnetic island chain driven at the relevant resonant surface is forced to rotate with respect to the RMP, because the RMP pulse amplitude is nowhere near sufficient to lock the island chain to the RMP. This rotation causes the critical RMP pulse amplitude required to trigger an NTM to oscillate as the RMP pulse duration is varied. The critical amplitude is minimized when the RMP pulse duration is such that seed island chain executes a half-integer number of rotations with respect to the pulse. All of the minima have the same value.
Multi-channel frequency difference noise analysis and cancellation method for the balanced field electromagnetic pipeline inspection gauge
Authors: Zheng Wenxue , Li Jiayin
Published: July 2023

The balanced field electromagnetic technique as an effective in-line inspection method for cracks in long-distance oil and gas pipelines uses the pipeline inspection gauge (PIG) as the detection tool. PIG is characterized by the employment of a large number of sensors, but as each channel uses its crystal oscillator as a signal source, it inevitably generates frequency difference noise, which affects crack detection. A method of eliminating the frequency difference noise by using same-frequency excitation is proposed to solve the problem. Combining the principle of electromagnetic field propagation with the detection signal processing process, the formation process and characteristics of the frequency difference noise are theoretically analyzed, and the specific impact of frequency difference noise on crack detection is analyzed. The method of unified clock excitation for all channels is adopted, and a same-frequency excitation system is developed. The correctness of the theoretical analysis and the validity of the proposed method are verified by platform experiments and pulling tests. The results show that the effect of the frequency difference on noise follows the whole detection process, and the smaller the frequency difference, the longer the noise period. The frequency difference noise distorts the crack signal and is of comparable magnitude to the crack signal, which tends to drown out the crack signal. The same-frequency excitation method can eliminate frequency difference noise at the source and has a high signal-to-noise ratio. The method can provide a reference for multi-channel frequency difference noise cancellation in other AC detection technologies.
A generalized grand-reaction method for modeling the exchange of weak (polyprotic) acids between a solution and a weak polyelectrolyte phase
Authors: Beyer David , Holm Christian
Published: July 2023

We introduce a Monte-Carlo method that allows for the simulation of a polymeric phase containing a weak polyelectrolyte, which is coupled to a reservoir at a fixed pH, salt concentration, and total concentration of a weak polyprotic acid. The method generalizes the established grand-reaction method by Landsgesell et al. [Macromolecules 53, 3007–3020 (2020)] and, thus, allows for the simulation of polyelectrolyte systems coupled to reservoirs with a more complex chemical composition. In order to set the required input parameters that correspond to a desired reservoir composition, we propose a generalization of the recently published chemical potential tuning algorithm of Miles et al. [Phys. Rev. E 105, 045311 (2022)]. To test the proposed tuning procedure, we perform extensive numerical tests for both ideal and interacting systems. Finally, as a showcase, we apply the method to a simple test system that consists of a weak polybase solution that is coupled to a reservoir containing a small diprotic acid. The complex interplay of the ionization of various species, the electrostatic interactions, and the partitioning of small ions leads to a non-monotonous, stepwise swelling behavior of the weak polybase chains.
Immiscible displacement flows in axially rotating pipes
Authors: Liu W. , Hassanzadeh H. , Larachi F. , Taghavi S. M.
Published: July 2023

We experimentally study buoyant immiscible displacement flows in an axially rotating pipe, with varying flow parameters, such as the mean imposed flow velocity, density difference, pipe rotation speed, and pipe inclination angle. Via employing image processing and ultrasound Doppler velocimetry techniques, we analyze key flow features, including displacement regimes, interfacial instabilities, interfacial front velocities, and velocity and concentration fields. We find that immiscible displacement flows are distinguished by the emergence of one or two heavy fluid fronts, particularly depending on the rotation speed. Furthermore, our dimensional analysis reveals that the displacement flow is governed by four dimensionless parameters, including the Reynolds, densimetric Froude (or Archimedes), and Rossby numbers, as well as the pipe inclination angle. Using these dimensionless groups, we succeed in categorizing the main flow regimes as efficient and inefficient displacements. Moreover, we classify the interfacial regimes as stable, intermittently unstable, kinks, and separating interfacial patterns. Our analysis shows that the interfacial instabilities observed are indeed characterized by the Kelvin–Helmholtz instability. Our analysis of the velocity fields suggests remarkable differences between displacements in stationary and rotating pipes, especially in terms of the absence and presence of a countercurrent flow, respectively. Finally, our assessment of concentration fields using a Fourier transform approach provides a preliminary fundamental understanding of the characteristics of concentration waves and their corresponding amplitudes.
Dynamics of droplet coalescence on a vibrating vertical surface
Authors: Royon Laurent , Guo Xiaofeng
Published: July 2023

A mass-spring-damper theoretical model with a phenomenological equation is established to clarify the underlying physics of the dynamics of droplets on a vertical surface driven by vibration. It is found experimentally and theoretically that the phase shift between droplet and plate appears and peaks at a lower frequency for a larger droplet. At a certain frequency, two droplets could move in the opposite direction. Based on the phase shift mechanism, we propose a strategy aimed at promoting droplet coalescence. Compared to the necessity of precise control of frequency for resonance-induced events, the strategy accepts a higher tolerance for frequency, at which opposite-motion-induced droplet coalescence could occur. The optimal frequency where there is a maximum phase shift between two droplets is derived, and a large-bandwidth frequency range, which allows at least 90% maximum phase shift, is defined. The good agreement between the experimental and theoretical results collectively shows that the motion of the larger droplet is in the opposite direction to that of the smaller one only at large-bandwidth frequency range and the two droplets coalesce with high enough amplitude. Our findings are helpful for the utilization of vibrating surfaces for droplet removal.
Phase transition of potassium sodium niobate under high pressures
Authors: Zhou Zhangyang , Fang Leiming , Xiong Zhengwei , Zhang Youjun , Liu Yixuan , Liu Gaomin , Liu Yi , He Ruiqi , Han Tiexin , Li Jun , Wang Ke , Gao Zhipeng
Published: July 2023

As a piezoelectric material, K0.5Na0.5NbO3 (KNN) has broad application prospects in ultrasonic transducers, sensors, and biomedicine areas. Its structure information under high pressures is of great significance for guiding device design. In this study, the high-pressure structural evolution of KNN has been studied. Two structural phase transitions were revealed by high-pressure Raman spectrum. The phase transition boundary was found by Raman vibration mode analysis, with transformation ranges of 2.5–4.6 and 6.8–9.4 GPa. The phase structures were determined by in situ neutron diffraction, with a phase transformation path of orthogonal Amm2 (O) → tetragonal P4mm (T) → cubic Pm3¯m (C) structure at high pressures. Synchrotron x-ray diffraction further confirmed the phase transformation path. During the processes of phase transitions, the path of Nb atom was clearly described as moving toward [1¯01] and then [100] direction. An output power density of KNN ceramic devices was comparable to that of commercially available PZT 95/5. The density of KNN ceramic is approximately half that of PZT 95/5, which means a significant advantage in terms of weight reduction and miniaturization of equipment in global demand. The phase transition of ferroelectric materials under high pressures provides scientific guidance for the development of high-power pulse power devices.
What chunking of microbiology learning materials looks like today using technology and learning objects
Authors: Grando Danilla
Published: July 2023

I have a saying printed and placed on my office wall, ‘Create learning environments so that all can meet the learning objectives’. It seems this task has become increasingly difficult to meet as students may be juggling a full-time workload and a full-time study load. However, this has been made possible as many programs no longer require students to sit exams, but rather are assessing students through activities and assignments. For students, finding the time to engage with lecture content competes with completing assessment activities. It is important to firstly give students the motivation for why completion of learning materials is important and then maintain their engagement with the learning materials. This article provides some techniques to help maintain student engagement through chunked learning activities.
Conversation and the evolution of metacognition
Authors: Planer Ronald J.
Published: July 2023

While the term “metacognition” is sometimes used to refer to any form of thinking about thinking, in cognitive
psychology, it is typically reserved for thinking about one’s own thinking, as opposed to thinking about others’ thinking. How
metacognition in this more specific sense relates to other-directed mindreading is one of the main theoretical issues debated in
the literature. This article considers the idea that we make use of the same or a largely similar package of resources in
conceptually interpreting our own mind as we do in interpreting others’. I assume that a capacity for other-directed mindreading
is minimally shared with our great-ape relatives, but I argue that the architecture of this system had to be substantially
modified before it could efficiently and adaptively be turned inwards on one’s own mind. I contend that an important piece of the
overall evolutionary explanation here likely concerns selection pressures arising from the domain of conversational interaction.
Specifically, drawing on work carried out in the human interaction studies tradition (e.g., conversation analysis), I argue that
the smooth to-and-fro of conversational interaction can be seen to heavily depend on metacommunicative capacities, which, in turn,
are underpinned by metacognitive capacities. I conclude with a thumbnail sketch of an evolutionary account of the emergence of
these metacognitive capacities in the human line. Their appearance and spread – whether via genes, cultural learning, or more
likely, some combination of the two – helps to explain the transition from great-ape communication to human conversation.