bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of planetary engulfment on stellar rotation in metal-poor main-sequence stars
Authors: Oetjens A. , Carone L. , Bergemann M. , Serenelli A.
Published: September 2020

Context. The method of gyrochronology relates the age of its star to its rotation period. However, recent evidence of deviations from gyrochronology relations has been reported in the literature.

Aims. We study the influence of tidal interaction between a star and its companion on the rotation velocity of the star to explain peculiar stellar rotation velocities.

Methods. We followed the interaction of a star and its planet using a comprehensive numerical framework that combines tidal friction, magnetic braking, planet migration, and detailed stellar evolution models from the GARSTEC grid. We focus on close-in companions from 1 to 20 MJup orbiting low-mass (0.8 − 1 M⊙) main-sequence stars with a broad metallicity of [Fe/H] = − 1 up to solar.

Results. Our simulations suggest that the dynamical interaction between a star and its companion can have different outcomes that depend on the initial semi-major axis and the mass of the planet, as well as on the mass and metallicity of its host star. In most cases, especially in the case of planet engulfment, we find a catastrophic increase in stellar rotation velocity from 1 kms−1 to over 40 kms−1 while the star is still on the main-sequence. The main prediction of our model is that low-mass main-sequence stars with abnormal rotation velocities should be more common at low-metallicity, as lower [Fe/H] favours faster planet engulfment, based on the assumption that the occurrence rate of close-in massive planets is similar at all metallicities.

Conclusions. Our scenario explains peculiar rotation velocities of low-mass main-sequence stars by the tidal interaction between the star and its companion. Current observational samples are too narrow and incomplete, and, thus, they are not sufficient for our model to be tested.
Rotation periods for cool stars in the open cluster Ruprecht 147 (NGC 6774)
Authors: Gruner D. , Barnes S. A.
Published: September 2020

Context. Gyrochronology allows the derivation of ages for cool main sequence stars based on their observed rotation periods and masses, or a suitable proxy thereof. It is increasingly well-explored for FGK stars, but requires further measurements for older ages and K – M-type stars.

Aims. We study the 2.7 Gyr-old open cluster Ruprecht 147 to compare it with the previously-studied, but far more distant, NGC 6819 cluster, and especially to measure cooler stars than was previously possible there.

Methods. We constructed an inclusive list of 102 cluster members from prior work, including Gaia DR2, and for which light curves were also obtained during Campaign 7 of the Kepler/K2 space mission. We placed them in the cluster color-magnitude diagram and checked the related information against appropriate isochrones. The light curves were then corrected for data systematics using Principal Component Analysis on all observed K2 C07 stars and subsequently subjected to periodicity analysis.

Results. Periodic signals are found for 32 stars, 21 of which are considered to be both highly reliable and to represent single, or effectively single, Ru 147 stars. These stars cover the spectral types from late-F to mid-M stars, and they have periods ranging from 6 d – 33 d, allowing for a comparison of Ruprecht 147 to both other open clusters and to models of rotational spindown. The derived rotation periods connect reasonably to, overlap with, and extend to lower masses the known rotation period distribution of the 2.5 Gyr-old cluster NGC 6819.

Conclusions. The data confirm that cool stars lie on a single surface in rotation period-mass-age space, and they simultaneously challenge its commonly assumed shape. The shape at the low mass region of the color-period diagram at the age of Ru 147 favors a recently-proposed model which requires a third mass-dependent timescale in addition to the two timescales required by a former model, suggesting that a third physical process is required to model rotating stars effectively.
Caractérisation acoustique de conduits auditifs externes normaux : de l’humain aux modèles imprimés 3D
Authors: Ramilison Eloi , Legouge Axel , Lucciano Michel , Masson Catherine , Deveze Arnaud
Published: September 2020

Objectif : Créer et valider un modèle de CAE normal par impression en 3D bio-fidèles aux CAE humains.

Méthodologie : Nous avons prélevé dix CAE humains sur des pièces anatomiques. Après acquisition volumique sur un scanner
conventionnel, la conception numérique des CAE en 3D comportait une segmentation et la mise en place d’un support tympanique.
Nous avons utilisé du PLA pour l’impression et du ruban adhésif pour simuler une MT artificielle. La vélocimétrie de l’umbo a été
mesurée au moyen d’un laser couplé à une chaine acoustique de stimulation-recueil dédiée.

Résultats : Comparés aux CAE humains, les modèles ont montré des réponses identiques statistiquement. Un second pic était observé
à 5 kHz sur le pattern des CAE imprimés. Les hautes fréquences montraient un profil plus chaotique.

Conclusion : Les CAE imprimés en 3D sont des modèles valides et bio-fidèles aux CAE humains. La normalisation des amplifications
observées permet d’obtenir un modèle utile pour l’optimisation des dispositifs d’amplification ou de protection auditifs.
Intelligence artificielle et réhabilitation auditive : état de la science
Authors: Ambert-Dahan Emmanuèle
Published: September 2020

Objectif : L’objectif de cet article est de faire état des interactions entre l’intelligence artificielle et la réhabilitation auditive en
montrant de quelle manière celle-ci est intégrée aux prothèses auditives conventionnelles, aux implants cochléaires et aux programmes
d’entraînement perceptivo-cognitif.

Méthodes : Il s’agit d’une revue de littérature effectuée au moyen de recherches bibliographiques référencées ainsi que sur internet
afin de recenser les innovations technologiques des fabricants de prothèses auditives conventionnelles et/ou d’implants cochléaires
ainsi que différents sites proposant des programmes d’entraînement en ligne.

Résultats : Ces recherches ont permis d’identifier des processus d’intelligence artificielle intégrés aux prothèses auditives conventionnelles,
aux processeurs et aux systèmes de réglage des implants cochléaires ainsi que des programmes d’entraînement en ligne.

Conclusion : Cette étude confirme l’existence de programmes d’entraînement auditif et cognitif informatisés n’intégrant pas
l’intelligence artificielle ce qui ne leur permet pas de s’ajuster aux comportements et aux attentes de leurs utilisateurs.
New regularity results and finite element error estimates for a class of parabolic optimal control problems with pointwise state constraints
Authors: Christof Constantin , Vexler Boris
Published: September 2020

We study first-order necessary optimality conditions and finite element error estimates for a class of distributed parabolic optimal control problems with pointwise state constraints. It is demonstrated that, if the bound in the state constraint and the differential operator in the governing PDE fulfil a certain compatibility assumption, then locally optimal controls satisfy a stationarity system that allows to significantly improve known regularity results for adjoint states and Lagrange multipliers in the parabolic setting. In contrast to classical approaches to first-order necessary optimality conditions for state-constrained problems, the main arguments of our analysis require neither a Slater point, nor uniform control constraints, nor differentiability of the objective function, nor a restriction of the spatial dimension. As an application of the established improved regularity properties, we derive new finite element error estimates for the dG(0) − cG(1)-discretization of a purely state-constrained linear-quadratic optimal control problem governed by the heat equation. The paper concludes with numerical experiments that confirm our theoretical findings.
Human resource practices and performance in small Spanish wineries, and their evolution with age and size
Authors: Ferrer Juan R. , Abella-Garcés Silvia , Maza-Rubio María T.
Published: September 2020

This research aims to cover the existing gap in knowledge regarding human resource management practices in winery businesses. Three of the most important practices in this field - recruitment and selection, training and development, and remuneration - and their relationship with performance in small family and non-family wineries as well as the differences in those businesses’ behaviours according to their age and size were analysed. The analysis was based on a 2016 database containing 339 Spanish wine sector SMEs, and a multivariate Bayesian regression methodology was applied. The results demonstrate a lower level of human resource management practices in small family businesses and a stronger relationship with performance than in non-family businesses. The results also show that human resource management varies according to the age and size of the company, indicating an inverted U-shaped relationship with size. On the one hand, these results highlight the importance of human resource practices in the environment of a small winery. These practices have not usually been considered as drivers of performance in small family firms. On the other hand, the results can be useful for the managers of such firms, both in the wine industry and in general, as they highlight the human resource practices that could improve the performance of those entities. The paper contributes to filling the existing gap in the literature related to small family businesses.
Modeling the dynamic behavior of laminated steels using a Fourier-based approach
Authors: Zeinali Reza , Krop Dave , Lomonova Elena
Published: September 2020

A new magneto-dynamic model is proposed to approximate the dynamic hysteresis effect in laminated steels considering the static hysteresis, eddy-current field, and excess field. An accurate congruency-based hysteresis model is used to predict the static hysteresis field. The eddy-current is determined from the 1D diffusion equation and the well-known Bertotti empirical equation is utilized to model the excess-field effect. The dynamic lamination model obtained from coupling three field components is solved using a Fourier-based approach. In this approach, the flux density across the lamination thickness is approximated by a cosine-based Fourier series. The coefficients of the Fourier series are determined by solving a system of nonlinear equations through an iterative procedure. Owing to the employed congruency-based static hysteresis model, the proposed magneto-dynamic model offers high accuracy for arbitrary magnetization regimes. To validate the model accuracy, the model results are compared with sinusoidal and multi-harmonic measurements. The comparison shows that the proposed model predicts the dynamic hysteresis phenomenon in laminated steels with a relative energy error of less than 7%.
Enhancement of the performance of CdS/CdTe heterojunction solar cell using TiO2/ZnO bi-layer ARC and V2O5 BSF layers: A simulation approach
Authors: Kuddus Abdul , Rahman Md. Ferdous , Hossain Jaker , Ismail Abu Bakar Md.
Published: September 2020

This article presents the role of Bi-layer anti-reflection coating (ARC) of TiO2/ZnO and back surface field (BSF) of V2O5 for improving the photovoltaic performance of Cadmium Sulfide (CdS) and Cadmium Telluride (CdTe) based heterojunction solar cells (HJSCs). The simulation was performed at different concentrations, thickness, defect densities of each active materials and working temperatures to optimize the most excellent structure and working conditions for achieving the highest cell performance using obtained optical and electrical parameters value from the experimental investigation on spin-coated CdS, CdTe, ZnO, TiO2 and V2O5 thin films deposited on the glass substrate. The simulation results reveal that the designed CdS/CdTe based heterojunction cell offers the highest efficiency, η of ∼25% with an enhanced open-circuit voltage, Voc of 0.811 V, short circuit current density, Jsc of 38.51 mA cm−2, fill factor, FF of 80% with bi-layer ARC and BSF. Moreover, it appears that the TiO2/ZnO bi-layer ARC, as well as ETL and V2O5 as BSF, could be highly promising materials of choice for CdS/CdTe based heterojunction solar cell.
Einfluss einer spontan bakteriellen Peritonitis, nosokomialer Infektionen und eines akut auf chronischen Leberversagens auf die Behandlungserlöse bei Patienten mit dekompensierter Leberzirrhose in Deutschland
Authors: Kabbani Abdul-Rahman , Schultalbers Marie , Tergast Tammo , Kimmann Markus , Stahmeyer Jona , Manns Michael P. , Cornberg Markus , Maasoumy Benjamin , Becker Hans
Published: September 2020

Einleitung Die ökonomischen Einflüsse einer spontan bakteriellen Peritonitis (SBP), nosokomialer Infektionen (nosInf) und eines akut auf chronischen Leberversagens (ACLF) sind bislang wenig untersucht. Wir analysierten die Einflüsse dieser Komplikationen auf die Behandlungserlöse von hospitalisierten Patienten mit dekompensierter Leberzirrhose.

Methodik 371 hospitalisierte, konsekutive Patienten mit Leberzirrhose und aszitischer Dekompensation, die zwischen 2012 und 2016 eine Parazentese erhielten, wurden retrospektiv eingeschlossen. DRG (Diagnosebezogene Fallgruppen), ZE/NUB (Zusatzentgelte/Neue Untersuchungs- und Behandlungsmethoden), Medikamentenkosten, Krankenhausverweildauer, therapeutische und klinische Leistungen (u. a. Dialyse, hochaufwendige Pflege) wurden für die Auswertung berücksichtigt. Ausschlusskriterien waren u. a. ein malignes Grundleiden, eine Organtransplantation sowie fehlende Abrechnungsdaten.

Ergebnisse Die Gesamterlöse (DRG + ZE/NUB) waren im Fall einer nosInf deutlich höher (10.653 € vs. 5.611 €; p < 0,0001) bei allerdings auch wesentlich längerer Krankenhausverweildauer (23 vs. 12 Tage, p < 0,0001). Die Erlöse/Tag unterschieden sich letztlich nicht (473 € vs. 488 €; p = 0,98). Die Behandlung bei nosInf war jedoch wesentlich aufwendiger mit häufigeren Dialysen (p < 0,0001) und hochaufwendiger Pflege (p = 0,0002). Analog ergaben sich bei einer SBP ebenfalls höhere Gesamterlöse (10.307 € vs. 6.659 €; p < 0,0001) bei jedoch deutlich höherem Behandlungsaufwand. Die Erlöse/Tag waren in diesen Fällen allerdings numerisch niedriger als bei Patienten ohne SBP (443 € vs. 499 €; p = 0,18). Das Auftreten eines ACLF erhöhte die Gesamterlöse auf 10.593 € vs. 6.369 € ohne ACLF (p < 0,0001). Auch dabei war der Behandlungsaufwand entsprechend größer (bspw. mehr Dialysen; p < 0,0001). Die Klinikerlöse/Tag waren mit und ohne ACLF jedoch nicht unterschiedlich (483 € vs. 480 €; p = 0,29).

Schlussfolgerung Bei dekompensierter Leberzirrhose führt das Auftreten einer SBP, nosokomialer Infektionen und/oder eines ACLF zu einer signifikanten Erhöhung des Behandlungsaufwands, der Erlöse und der Krankenhausverweildauer. Die dazu im Widerspruch stehenden numerisch niedrigeren Erlöse/Tag bei wesentlich höherer Zahl erbrachter Leistungen weisen möglicherweise darauf hin, dass diese Komplikationen im deutschen DRG-System zurzeit nicht ausreichend berücksichtigt werden.
Biomarkers and Redox Balance in Aging Rats after Dynamic and
Isometric Resistance Training
Authors: Neves Rodrigo Vanerson Passos , Rosa Thiago dos Santos , Corrêa Hugo Luca , da Silva Aires Kethelen Mariana , Deus Lysleine Alves , Sousa Michel Kendy , Stone Whitley Jo , Aguiar Lana Ribeiro , Prestes Jonato , Simões Herbert Gustavo , Andrade Rosângela Vieira , Moraes Milton Rocha
Published: September 2020

Aging muscle is prone to sarcopenia and its associated telomere shortening and
increased oxidative stress. Telomeres are protected by a shelterin protein
complex, proteins expressed in response to DNA damage. Aerobic exercise training
has shown to positively modulate these proteins while aging, but the effects of
resistance training are less clear. This investigation was to examine the role
of dynamic and isometric RT on markers of senescence and muscle apoptosis:
checkpoint kinase 2, 53 kDa protein, shelterin telomere repeat binding 1
and 2, DNA repair, telomere length and redox state in the quadriceps muscle.
Fifteen 49-week-old male rats were divided into three groups: control, dynamic
resistance training, and isometric resistance training. Dynamic and isometric
groups completed five sessions per week during 16 weeks at low to moderate
intensity (20–70% maximal load). Only dynamic group decreased
expression of 53 kDa protein, proteins from shelterin complex, oxidative
stress, and improved antioxidant defense. There was no difference among groups
regarding telomere length. In conclusion, dynamic resistance training was more
effective than isometric in reducing markers of aging and muscle apoptosis in
elderly rats. This modality should be considered as valuable tool do counteract
the deleterious effects of aging.
Are Early-Onset Sepsis Evaluations and Empiric Antibiotics Mandatory for All Neonates Admitted with Respiratory Distress?
Authors: Capin Ivana , Hinds Autumn , Vomero Bridgit , Roth Philip , Blau Jonathan
Published: September 2020

Objective The objective of this study was to evaluate the success and safety of an antimicrobial stewardship protocol for neonates admitted with respiratory distress at birth.

Study Design A retrospective cohort analysis of all infants admitted to the neonatal intensive care unit (NICU) with respiratory distress from January 2013 to February 2018 was conducted. In April 2016, an antimicrobial stewardship protocol was implemented, dividing neonates into two groups: maternal indications for delivery (no infectious risk factors for early-onset sepsis [EOS]) and fetal indications (risk factors present) for delivery. Neonates with risk factors for EOS were started on empiric antibiotics, those who lacked risk factors were observed. Paired sample t-test and descriptive statistics were used to compare the pre- and postprotocol implementation.

Results There were no missed cases of EOS in our study. Management with empiric antibiotics decreased from 95 to 41% of neonates with respiratory distress after initiation of the protocol. Newborns with a lower mean (±standard errors of the mean [SEM]) gestational age were more likely to receive empiric antibiotics (35.1 ± 0.4 [range: 23–42 weeks] vs. 37.7 ± 0.2 weeks [range: 24–42 weeks]; p < 0.05). Similar findings were seen for neonates with lower mean birth weights (2,627 ± 77 [range: 390–5,440 g] vs. 3,078 ± 51 g [range: 620–6,260 g]; p < 0.05).

Conclusion The antibiotic stewardship protocol safely reduces the administration of empiric antibiotics to symptomatic neonates without missing any cases of sepsis.

Key Points
Enhancing the possibility of using curcumin for breast cancer treatment
Authors: Frank Jodi Ackerman
Published: September 2020

By conjugating it with folate on gold nanoparticles, curcumin may be used as an anticancer drug.
Experimental consideration of two-dimensional Fourier transform spectroscopy
Authors: Zhou Liang , Tian Lie , Zhang Wen-kai
Published: September 2020

Two-dimensional Fourier transform (2D FT) spectroscopy is an important technology that developed in recent decades and has many advantages over other ultrafast spectroscopy methods. Although 2D FT spectroscopy provides great opportunities for studying various complex systems, the experimental implementation and theoretical description of 2D FT spectroscopy measurement still face many challenges, which limits their wide application. Recently, the 2D FT spectroscopy reaches maturity due to many new developments which greatly reduces the technical barrier in the experimental implementation of the 2D FT spectrometer. There have been several different approaches developed for the optical design of the 2D FT spectrometer, each with its own advantages and limitations. Thus, a procedure to help an experimentalist to build a 2D FT spectroscopy experimental apparatus is needed. This tutorial review is intending to provide an accessible introduction for a beginner to build a 2D FT spectrometer.
An urban commuters’ OD hybrid prediction method based on big GPS data
Authors: Wang Yongdong , Xu Dongwei , Peng Peng , Xuan Qi , Zhang Guijun
Published: September 2020

With the quick development of mobile Internet and communication technology, the use of Global Position System (GPS)-enabled devices is rapidly increasing, which facilitates the collection of huge volumes of movement data in the form of trajectories. Trajectory data contain a lot of commuters’ travel information, which offer convenience for researchers to study traffic problems and to mine urban commuters’ travel information. In this paper, we represent an urban commuters’ origin–destination (OD) hybrid prediction method based on big GPS data, which considers the temporal and spatial dependencies of OD volume data simultaneously. The regional division was performed based on a simple grid map, and the data for each grid can be obtained. Based on the grids, the OD pairs can be constructed and the network topology of OD pairs can be established. A graph convolutional network and a long short-term memory deep learning method were introduced to capture the temporal and spatial dependencies, respectively. In addition, an attention mechanism was used to learn the weights of input data. The numerical experiment was performed based on the GPS data in Chengdu, China, and some comparisons were made. The results demonstrated that the proposed hybrid OD prediction method was significant and the accuracy was reasonable.
Twin defect-triggered deformations and Bi segregation in GaAs/GaAsBi core–multishell nanowires
Authors: Matsuda Teruyoshi , Takada Kyohei , Yano Kohsuke , Shimomura Satoshi , Shimizu Yumiko , Ishikawa Fumitaro
Published: September 2020

We investigated microstructural deformations and Bi segregation in GaAs/GaAsBi/GaAs core–multishell heterostructures, which were triggered by the existence of twin defects. We observed Bi segregation at the interface of the twin defect interface in the GaAsBi shell. The phenomenon produced a horizontally spread Bi-accumulated nanostructure in the nanowire, which is probably induced by the large lattice mismatch between GaAs and GaAsBi. Bi is expected to penetrate through the twin defect interface, which results in the existence of Bi along twin defects and also inside the GaAs core. The existence of twin defects induced structural deformations and resulted in the formation of corrugated complex sidewall surfaces on the nanowire.
Radical scavenging activity of natural antioxidants and drugs: Development of a combined machine learning and quantum chemistry protocol
Authors: Muraro Cecilia , Polato Mirko , Bortoli Marco , Aiolli Fabio , Orian Laura
Published: September 2020

Many natural substances and drugs are radical scavengers that prevent the oxidative damage to fundamental cell components. This process may occur via different mechanisms, among which, one of the most important, is hydrogen atom transfer. The feasibility of this process can be assessed in silico using quantum mechanics to compute ΔGHAT○. This approach is accurate, but time consuming. The use of machine learning (ML) allows us to reduce tremendously the computational cost of the assessment of the scavenging properties of a potential antioxidant, almost without affecting the quality of the results. However, in many ML implementations, the description of the relevant features of a molecule in a machine-friendly language is still the most challenging aspect. In this work, we present a newly developed machine-readable molecular representation aimed at the application of automatized ML algorithms. In particular, we show an application on the calculation of ΔGHAT○.
Individual contribution of electrons and holes to photocarrier-induced bandgap renormalization in intrinsic bulk GaAs
Authors: Chen Yicun , Lu Haiming , Lai Tianshu
Published: September 2020

With the advent of semiconductor spintronics, spin-polarized electron–hole plasmas could occur in semiconductors, leading to spin-dependent many-body effects. To understand these many-body effects, spin-dependent bandgap renormalization (BGR) often needs to be calculated quantitatively, which requires to know the fractional contribution of electrons (k) to the total BGR induced by the electron–hole plasma. However, the measurement of the k value is challenging because BGR is usually submerged or partially offset by the strong band-filling effect. Facing this challenge, we develop a new experimental technique which could measure spin-dependent many-body effects without the influence from the band-filling effect. The presented technique is employed in intrinsic bulk GaAs, with a dynamic model developed to extract the k value from the measured data. It is found that the k value in bulk GaAs increases with increasing concentration of the photoinjected electron–hole plasma but is consistently much less than the reported value in GaAs quantum wells. These results reveal obviously different many-body interactions in bulk GaAs and its quantum wells.
Clusterization and phase diagram of the bimodal Kuramoto model with bounded confidence
Authors: Reggio André , Delabays Robin , Jacquod Philippe
Published: September 2020

Inspired by the Deffuant and Hegselmann–Krause models of opinion dynamics, we extend the Kuramoto model to account for confidence bounds, i.e., vanishing interactions between pairs of oscillators when their phases differ by more than a certain value. We focus on Kuramoto oscillators with peaked, bimodal distribution of natural frequencies. We show that, in this case, the fixed-points for the extended model are made of certain numbers of independent clusters of oscillators, depending on the length of the confidence bound—the interaction range—and the distance between the two peaks of the bimodal distribution of natural frequencies. This allows us to construct the phase diagram of attractive fixed-points for the bimodal Kuramoto model with bounded confidence and to analytically explain clusterization in dynamical systems with bounded confidence.
Electric field induced dynamics of viscoplastic droplets in shear flow
Authors: Nath Binita , Borthakur Manash Pratim , Biswas Gautam
Published: September 2020

We investigate the dynamics of viscoplastic droplets under the combined action of electric field and shear flow by performing direct numerical simulations. The electro-hydrodynamic equations are solved in a two-dimensional finite volume framework, and the interface is captured using a volume-of-fluid approach. The rheology of the viscoplastic droplet is modeled as a Bingham plastic fluid. Both the drop and the surrounding medium are considered to be perfect dielectric fluids. The simulations reveal that in the sole presence of the shear flow, the plasticity of the fluid plays a pivotal role in deciding the magnitude of droplet deformation and orientation. The local viscosity inside the drop is significantly augmented for higher plasticity of the fluid. Under the action of the electric field, the droplet deformation and orientation can be suitably tuned by varying the magnitude of the permittivity contrast between the fluids. The droplets experience enhanced deformation and preferred orientation against the flow direction when the permittivity ratio is greater than unity. Increasing the droplet plasticity leads to reduction in the droplet deformation. Conversely, by increasing the electric field strength, the deformation of the droplets can be notably enhanced, with a stronger response observed for a permittivity ratio beyond unity. Finally, it is observed that by suitably manipulating the strength of the shear flow and the electric field, droplet breakup can be engendered. The mode of droplet disintegration differs due to variation of the parameters, which can be attributed to the competing influence of shear and electric forces on the droplet.
Scaling behavior and variable-range-hopping conduction of localized polarons in percolative BaTiO3-Ni0.5Zn0.5Fe2O4 ceramic composite with colossal apparent permittivity
Authors: Xiao Bin , Tang Yu , Pan Desheng , Du Piyi , Wang Hong
Published: September 2020

The percolative BaTiO3-Ni0.5Zn0.5Fe2O4 (BTO-NZFO) ceramic composite represents a family of multifunctional materials exhibiting multiferroic properties and colossal apparent permittivity. It is of fundamental interest to investigate the conduction mechanism in such percolative composites from both macroscopic and microscopic perspectives. Herein, three representative systems with the NZFO content locating below the percolation threshold fc, near fc, and above fc, respectively, were investigated, using pure NZFO ceramic as a comparison. The conductivity of the composite as a function of NZFO content agrees well with the McLachlan model, which takes percolation into consideration and essentially equivalent to the Kirkpatrick model. The electrical conductivity of the composite conforms to Mott's variable-range-hopping (VRH) model in the temperature range of 303–573 K, suggesting that VRH conduction of localized polarons dominates the electrical behavior microscopically. Parameters including the most probable hopping range (R); the density of localized states at the Fermi level [N(EF)]; and the activation energies of VRH (W), dc conductivity (Edc), hopping (Eon), and relaxation (Er) were obtained and analyzed. Scaling behaviors of the conductivity and the imaginary part of complex impedance of the composite have been observed, implying that the distribution of relaxation times is temperature independent. The impedance data measured at different temperatures exhibit typical semiconducting behavior, which can be well fitted by an equivalent circuit model considering both grain and grain boundary responses. The correlation between conductivity and colossal apparent permittivity has also been revealed. The discoveries deepen the understanding of the conduction mechanism in such multifunctional composites composed of an insulating phase and a semiconducting phase.
Formation of zero-field skyrmion arrays in asymmetric superlattices
Authors: Li Maxwell , Rai Anish , Pokhrel Ashok , Sapkota Arjun , Mewes Claudia , Mewes Tim , Graef Marc De , Sokalski Vincent
Published: September 2020

We demonstrate the formation of metastable Néel-type skyrmion arrays in Pt/Co/Ni/Ir multi-layers at zero-field following the ex situ application of an in-plane magnetic field using Lorentz transmission electron microscopy. The resultant skyrmion texture is found to depend on both the strength and misorientation of the applied field as well as the interfacial Dzyaloshinskii–Moriya interaction. To demonstrate the importance of the applied field angle, we leverage bend contours in the specimens, which coincide with transition regions between skyrmion and labyrinth patterns. The subsequent application of a perpendicular magnetic field near these regions reveals the unusual situation where skyrmions with opposite magnetic polarities are stabilized in close proximity.
How general practitioners perceive access needs of vulnerable patients and act to address these needs: a mixed-methods study in south-east Melbourne, Australia
Authors: Kunin Marina , Advocat Jenny , Wickramasinghe Suhashi M. , Dionne Emilie , Russell Grant
Published: September 2020

ObjectiveThe aim of this study was to understand primary health care (PHC) access barriers for vulnerable people living in south-east Melbourne from the perspective of general practitioners (GPs) who work in the area and to outline strategies that GPs have used to address these barriers.
MethodsA convergent mixed-methods design was used. Quantitative surveys were conducted with practice managers and GPs, and semistructured qualitative interviews were undertaken with GPs. Data were analysed using a thematic framework approach.
ResultsEach of the vulnerable groups frequently seen by GPs in south-east Melbourne is thought to encounter access barriers in one or more access domains. GPs reported: (1) improving transparency, outreach and information on available treatments to address limited health literacy; (2) using culturally sensitive and language-speaking staff to overcome cultural stereotypes; (3) making practice-level arrangements to overcome limited mobility and social isolation; (4) bulk billing and helping find affordable services to overcome financial hardship; and (5) building trusting relationships with vulnerable patients to improve their engagement with treatment.
ConclusionGPs understand the nature of access barriers for local vulnerable groups and have the potential to improve equitable access to primary health care. GPs need support in the on-going application and further development of strategies to accommodate access needs of vulnerable patients.
What is known about the topic?Access to primary health care (PHC) is integral to reducing gaps in health outcomes for vulnerable groups. Vulnerable groups often encounter challenges in accessing PHC, and GPs have the potential to improve PHC access.
What does this paper add?GPs thought that the vulnerable patients they frequently treat encounter barriers pertaining to both patient access abilities and service accessibility. They reported addressing these barriers by improving transparency, outreach and information on available treatments; using culturally sensitive and multilingual staff; making practice-level arrangements to overcome limited mobility and social isolation; bulk billing and helping find affordable services; and building trusting relationships with vulnerable patients.
What are the implications for practitioners?Understanding the nature of access barriers for local vulnerable groups and information on strategies used by GPs allows for the further development of PHC access strategies.
Language contact and its effects on language use of the Gurage varieties of
Muher
Authors: Shumneka Nurga Awlachew
Published: September 2020

Social and linguistic contact between speakers of diverse
Gurage varieties, as well as the influence of the surrounding Cushitic languages,
has contributed to the establishment of widespread bi- or multilingualism. However,
the actual extent and effects of language contact in the Gurage Zone are not clearly
known. Therefore, the main objective of this research is to investigate language
contact and its effects on language use of Muher. The Muher community lives in the
north-western part of the Gurage Zonal administration of the Southern Nations,
Nationalities, and Peoples’ Regional State. Muher speakers are bilingual in
Amharic, the official working language of the country, and Ezha, one of neighboring
languages the Gurage varieties. A mixed research method is used for data collection.
The findings show that Muher is often used in the home and within the community, and
is highly influenced by the dominant official working language of the country,
Amharic, and the neighboring language, Ezha. It is very hard to find monolingual
speakers of Muher. Amharic is used in all official settings in Muher, such as in
schools, in court, in health centre’s and in administration. Muher children are
bilingual with Amharic prior to starting school. Elders tend to use their mother
tongues, while young people mix their mother tongue with the dominant language, or
tend to speak Amharic. Generational transformation of Muher is decreasing in urban
areas. In Wolkite and Hawariyat, most of the children have Amharic as their L1.
Tissue-wide coordination of epithelium-to-neural stem cell transition in the Drosophila optic lobe requires Neuralized
Authors: Shard Chloé , Luna-Escalante Juan , Schweisguth François
Published: September 2020

Many tissues are produced by specialized progenitor cells emanating from epithelia via epithelial-to-mesenchymal transition (EMT). Most studies have so far focused on EMT involving single or isolated groups of cells. Here we describe an EMT-like process that requires tissue-level coordination. This EMT-like process occurs along a continuous front in the Drosophila optic lobe neuroepithelium to produce neural stem cells (NSCs). We find that emerging NSCs remain epithelial and apically constrict before dividing asymmetrically to produce neurons. Apical constriction is associated with contractile myosin pulses and involves RhoGEF3 and down-regulation of the Crumbs complex by the E3 ubiquitin ligase Neuralized. Anisotropy in Crumbs complex levels also results in accumulation of junctional myosin. Disrupting the regulation of Crumbs by Neuralized lowered junctional myosin and led to imprecision in the integration of emerging NSCs into the front. Thus, Neuralized promotes smooth progression of the differentiation front by coupling epithelium remodeling at the tissue level with NSC fate acquisition.
Lineage-specific regulation of inducible and constitutive mast cells in allergic airway inflammation
Authors: Derakhshan Tahereh , Samuchiwal Sachin K. , Hallen Nils , Bankova Lora G. , Boyce Joshua A. , Barrett Nora A. , Austen K. Frank , Dwyer Daniel F.
Published: September 2020

Murine mast cells (MCs) contain two lineages: inducible bone marrow–derived mucosal MCs (MMCs) and constitutive embryonic-derived connective tissue MCs (CTMCs). Here, we use RNA sequencing, flow cytometry, and genetic deletion in two allergic lung inflammation models to define these two lineages. We found that inducible MCs, marked by β7 integrin expression, are highly distinct from airway CTMCs at rest and during inflammation and unaffected by targeted CTMC deletion. β7High MCs expand and mature during lung inflammation as part of a TGF-β–inducible transcriptional program that includes the MMC-associated proteases Mcpt1 and Mcpt2, the basophil-associated protease Mcpt8, granule components, and the epithelial-binding αE integrin. In vitro studies using bone marrow–derived MCs (BMMCs) identified a requirement for SCF in this TGF-β–mediated development and found that epithelial cells directly elicit TGF-β–dependent BMMC up-regulation of mMCP-1 and αE integrin. Thus, our findings characterize the expansion of a distinct inducible MC subset in C57BL/6 mice and highlight the potential for epithelium to direct MMC development.
Attractors of the ‘n
+ 1’ dimensional Einstein-Λ flow
Authors: Mondal Puskar
Published: September 2020

Here we prove a global existence theorem for sufficiently small however fully nonlinear perturbations of a family of background solutions of the ‘n + 1’ dimensional vacuum Einstein equations in the presence of a positive cosmological constant Λ. The future stability of vacuum solutions in the small data and zero cosmological constant limit has been studied previously for both ‘3 + 1’ and higher dimensional spacetimes. However, with the advent of dark energy driven accelerated expansion of the Universe, it is of fundamental importance in mathematical cosmology to include a positive cosmological constant, the simplest form of the dark energy for the vacuum Einstein equations. Such Einsteinian evolution is here designated as the ‘Einstein-Λ’ flow. We study the background solutions of this ‘Einstein-Λ’ flow in ‘n + 1’ dimensional spacetimes in constant mean curvature spatial harmonic gauge, n ⩾ 3 and establish both linear and non-linear stability of such solutions. In the cases of number of spatial dimensions being strictly greater than 3, the finite dimensional Einstein moduli spaces form the centre manifolds of the dynamics. A suitable shadow gauge condition [Andersson L and Moncrief V 2011 J. Differ. Geom.
89 1–47] is implemented in order to treat these cases. In addition, the autonomous character of the suitably re-scaled Einstein flow breaks down as a consequence of including Λ(>0). We construct a Lyapunov functional (controlling a suitable norm of the small data) similar to a wave equation type energy for the non-linear non-autonomous evolution of the data and prove its decay in the direction of cosmological expansion utilizing the structure of the non-autonomous terms and smallness assumption on the data. Our results demonstrate the future stability and geodesic completeness of the perturbed spacetimes, and show that the scale-free geometry converges to an element of the space of constant negative scalar curvature metrics sufficiently close to and containing the Einstein moduli space (a point for n = 3 and a finite dimensional space for n > 3), which has significant consequences for the cosmic topology while restricting to the case of n = 3.
Strong terawatt pulses for the efficient plasma-based x-rays generation in flat water jet
Authors: Ponomareva E A , Zhukova M O , Ismagilov A O , Scheglov P A , Chaschin M V , Nazarov M M , Tsypkin A N
Published: September 2020

By using subpicosecond terawatt infrared pulses, we demonstrate strong x-rays generation in flat water jet. Varying the pump energy, pulse duration and its chirp along with measuring the angular x-ray distribution, we define the conditions which allow achieving the most intense x-ray emission. The terawatt powers made it possible to reveal two characteristic regimes of x-ray pulse energy dependence, namely, quasi-quadratic growth and the following saturation. The strong asymmetry of the x-ray yield dependences on the pump pulse duration for various chirp signs and the positive chirp preference correspond to the earlier studies and are mainly determined by the change in the electron temperature. Theoretical analysis of ionized electrons density dynamics reveals strong correlation with x-rays experimental data. We believe, our findings can be a promising basis for further development of highly intense femtosecond x-ray generators based on the metallic soluble substances.
Consistent evaluation of continuum scale properties of two-dimensional materials: a case study on graphene
Authors: Gandhi Sourabh S , Patra Puneet Kumar
Published: September 2020

We handshake statistical mechanics with continuum mechanics to develop a methodology for consistent evaluation of the continuum scale properties of two-dimensional materials. The methodology is tested on pristine graphene. Our scope is kept limited to elastic modulus, E, which has been reported to vary between 0.912 TPa and 7 TPa, Poisson’s ratio, ν, which has been reported to vary from being negative to a value as large as 0.46, and effective thickness, q, whose value varies between 0.75 Å and 3.41 Å. Such a large scatter arises due to inconsistent evaluation of these properties and making assumptions that may not be valid at atomistic scales. Our methodology combines three separate methods: uniaxial tension, equibiaxial tension, and flexural out-of-plane free vibrations of simply supported sheets, which, when used in tandem in molecular dynamics, can provide consistent values of E, ν and q. The only assumption made in the present study is the validity of the continuum scale thin plate vibration equation to represent the free vibrations of a graphene sheet. Our results suggest that—(i) graphene is auxetic in nature, (ii) E decreases with increasing size and temperature, and (iii) the effective thickness q increases with increasing size and temperature. Further, a robustness study of the computed mechanical properties shows consistent results, with differences varying between 1.4% and 6%.
Accuracy evaluation of geometric error calibration using a laser tracer via a formulaic approach
Authors: Cong Hongdong , Zha Jun , Li Linhui , Li Yipeng , Chen Yaolong
Published: September 2020

In this work, we examine the accuracy of the geometric error calibration of machine tools using a laser tracer, via the multilateration or sequential multilateration principle. An uncertainty analysis of geometric errors or target point coordinates, based on the Monte-Carlo method, is often adopted to assess the accuracy of measurement results. However, this approach is not comprehensive, and can be time-consuming. This paper adopts the average volumetric localization accuracy to assess the quality of geometric error calibration, where the accuracy is evaluated approximately by means of a formulaic method, based on the multivariate law of propagation of uncertainty. Using this method, the accuracy of measurement results can be denoted quantitatively with a single indicator, and the influence of measurement strategy on measurement accuracy can be analyzed more intuitively. To further improve the average volumetric localization accuracy, we employ an optimization method for the measurement path, based on the greedy algorithm. Simulations and experiment are then conducted to verify the proposed method; the results show that both the laser tracer setup and measurement path have a great deal of influence on the measurement accuracy of geometric errors.
One-step synthesis of carbon nanospheres with an encapsulated iron-nickel nanoalloy and its potential use as an electrocatalyst
Authors: Gonzalez-Reyna Marlen , Rodriguez-Lopez Aaron , Pérez-Robles Juan Francisco
Published: September 2020

For many years, in electrochemical processes, carbon nanostructures with metal support have been employed as electrodes due to their high surface area, chemical stability, and excellent performance as catalyst support by allowing a better electronic transfer. Nevertheless, on the surface, metallic nanoparticles are susceptible to corrosion. Instead, by encapsulating individual nanoparticles, they are protected. Among the carbon nanostructures, the most common are graphene, carbon nanotubes (CNTs), and carbon nanospheres (CNSs). Unlike CNTs and CNSs, graphene is difficult to obtain in mass production, limiting their applications. Regarding CNTs and CNSs, the latter presents better catalytic activity. Nonetheless, the process of synthesis of CNSs with metal inside is commonly made by time-consuming autoclave processes, some involving more than 43 h, and hence are expensive. Here, we suggest an advantageous synthesis of CNSs with an iron–nickel alloy encapsulated inside, by using a one-step chemical vapor deposition (CVD) process in less than 3 h. This material has potential applications for environmental and energy processes. According to the authors, the uses of iron-nickel alloys as an electrocatalyst for the ammonia oxidation reaction has not been proved. Thus, we evaluate the composite as an electrocatalyst for the ammonia oxidation reaction, an electrochemical process that offers environmental remediation and hydrogen as a fuel. The electrochemical characterization shows that the use of a bimetallic electrode improves the catalytic activity. In this case, nickel is the active specie and iron is the metal added which reduces the reaction potential. Besides, the composite presents high specific capacitance, better than other materials proposed such as graphene decorated with FeNi alloys. This behavior can be related to the variation of the catalyst morphology (supported vs. encapsulated) by improving the catalyst dispersion and particle size stabilization.
Separate absorption and multiplication solar-blind photodiodes based on p-NiO/MgO/n-ZnO heterostructure
Authors: Hwang Jun Dar , Wu Meng-Shu
Published: September 2020

High-performance solar-blind separate absorption and multiplication avalanche photodiodes (SAM-APDs) were fabricated based on a p-NiO/MgO/n-ZnO dual heterojunction structure. The prepared SAM-APDs exhibited a separated absorption and multiplication structure that used NiO and ZnO as absorption layers, and ultrawide-bandgap MgO as a multiplication layer. When the reverse-bias voltage exceeded 6 V, carrier avalanche multiplication occurred, and the avalanche gain reached a high value of 2.7 × 103, corresponding to a 1120% quantum efficiency, at a reverse-bias voltage of 10 V. These solar-blind SAM-APDs had an ultraviolet (UV) (310 nm)/visible (500 nm) rejection ratio as high as 563.6 at a 2 V reverse-bias voltage. These features render the SAM-APDs highly suitable for practical applications as UV solar-blind photodetectors.