bluuebunny/crossref_metadata_2025 huggingface dataset:
Distributed event-triggered adaptive partial diffusion strategy under dynamic network topology
Authors: Feng Minyu , Deng Shuwei , Chen Feng , Kurths Jürgen
Published: June 2020

In wireless sensor networks, the dynamic network topology and the limitation of communication resources may lead to degradation of the estimation performance of distributed algorithms. To solve this problem, we propose an event-triggered adaptive partial diffusion least mean-square algorithm (ET-APDLMS). On the one hand, the adaptive partial diffusion strategy adapts to the dynamic topology of the network while ensuring the estimation performance. On the other hand, the event-triggered mechanism can effectively reduce the data redundancy and save the communication resources of the network. The communication cost analysis of the ET-APDLMS algorithm is given in the performance analysis. The theoretical results prove that the algorithm is asymptotically unbiased, and it converges in the mean sense and the mean-square sense. In the simulation, we compare the mean-square deviation performance of the ET-APDLMS algorithm and other different diffusion algorithms. The simulation results are consistent with the performance analysis, which verifies the effectiveness of the proposed algorithm.
Analytic intermolecular potential energy surface and first-principles prediction of the rotational profiles for a symmetric top ion-atom complex: A case study of H3O+–Ar
Authors: Hou Dan , Yang Ji-Tai , Zhai Yu , Zhang Xiao-Long , Liu Jing-Min , Li Hui
Published: June 2020

We presented the first three-dimensional (3D) ab initio intermolecular potential energy surface (PES) for the H3O+–Ar complex. The electronic structure computations were carried out at the explicitly correlated coupled cluster theory-F12 with an augmented correlation-consistent triple zeta basis set. Analytic 3D PES was obtained by least-squares fitting the multi-dimensional Morse/Long-Range (mdMLR) potential model to interaction energies, where the mdMLR function form was applied to the nonlinear ion–atom case for the first time. The 3D PES fitting to 1708 points has root-mean-square deviations of 0.19 cm−1 with only 108 parameters for interaction energies less than 500 cm−1. With the 3D PES of the H3O+–Ar complex, we employed the combined radial discrete variable representation/angular finite basis representation method and Lanczos algorithm to calculate rovibrational energy levels. The rotational profiles of the O–H anti-stretching vibrational bands of v3+(S)←0+ and v3−(A)←0− for the H3O+–Ar complex were predicted and were in good agreement with the experimental results.
Moist-convective thermal rotating shallow water model
Authors: Kurganov Alexander , Liu Yongle , Zeitlin Vladimir
Published: June 2020

We show how the moist-convective rotating shallow water model, where the moist convection and the related latent heat release are incorporated into the standard rotating shallow water model of the atmosphere, can be improved by introducing, in a self-consistent way, horizontal gradients of potential temperature and changes of the latter due to the condensation heating, radiative cooling, and ocean-atmosphere heat fluxes. We also construct the quasi-geostrophic limit of the model in mid-latitudes and its weak-gradient limits in the equatorial region. The capabilities of the new model are illustrated by the examples of convection-coupled gravity waves and equatorial waves produced by the relaxation of localized pressure and potential temperature anomalies in the presence of moist convection.
Characterization and analysis of low-temperature time-to-failure behavior in forward-biased Schottky-type p-GaN gate HEMTs
Authors: He Jiabei , Wei Jin , Li Yang , Zheng Zheyang , Yang Song , Huang Baoling , Chen Kevin J.
Published: June 2020

The low-temperature gate reliability of Schottky-type p-GaN gate AlGaN/GaN heterojunction field-effect transistors under forward gate voltage stress is investigated. Both temperature-accelerated and voltage-accelerated time-dependent gate breakdown stress experiments are performed. The p-GaN gate exhibits a shorter time-to-failure at a lower temperature. It is found that the time-to-failure at “use conditions” predicted by acceleration tests at high gate bias stress could be overestimated at low temperatures. Such a discrepancy stems from the distinct dominant gate leakage mechanisms at high/low gate bias stress conditions. The dominant physical mechanism of the low-temperature gate leakage current is identified to be Poole–Frenkel emission at low gate bias and Fowler–Nordheim tunneling at high bias. From the physical model, a more accurate lifetime projection can be obtained for given use conditions.
A computational fluid dynamics approach for full characterization of muffler without and with exhaust flow
Authors: Liu L. Y. , Zheng X. , Hao Z. Y. , Qiu Y.
Published: June 2020

Compared to the linear frequency domain method, the transient Computational Fluid Dynamics (CFD) method is more effective when analyzing the effect of complex flow in the muffler on its acoustic characteristics. However, most of the existing CFD methods focus on the calculation of the transmission loss (TL) for the muffler only. The other evaluation parameters, such as noise reduction (NR), are rarely investigated. In this paper, a CFD approach was developed systematically for charactering TL, NR, and transfer matrix (TM) of the muffler in the cases without and with exhaust flow. In the proposed approach, only one mesh model with a correction pipe is needed based on two simulation runs. The non-reflective boundary was used as the termination of the correction pipe in the calculation for the TL, while the reflective pressure boundary was set on the correction pipe end in the calculation for the NR. The TM was then derived from the time-domain pressure and mass velocity obtained in the previous runs for calculating TL and NR. The proposed CFD approach was applied to two simple expansion chambers, and the computational predictions of TL, NR, and TM were validated successfully both with the measured results and the analytical results. In conclusion, the proposed CFD approach is effective for full characterization (TL, NR, and TM) of exhaust mufflers without and with exhaust flow.
Necessary and sufficient conditions for quasisymmetry
Authors: Rodríguez E. , Helander P. , Bhattacharjee A.
Published: June 2020

A necessary and sufficient set of conditions for a quasisymmetric magnetic field in the form of constraint equations is derived from first principles. Without any assumption regarding the magnetohydrodynamic (MHD) equilibrium of the plasma, conditions for quasisymmetry are constructed starting from the single-particle Lagrangian to the leading order. The conditions presented in the paper are less restrictive than the set recently obtained by Burby et al. [“Some mathematics for quasi-symmetry,” arXiv:1912.06468 (2019)], and could facilitate ongoing efforts toward investigating the existence of global quasisymmetric MHD equilibria. It is also shown that quasisymmetry implies the existence of flux surfaces, regardless of whether the field corresponds to an MHD equilibrium.
Effects of a nano-scale embossed surface on the acoustic emission of air-coupled piezoelectric ultrasonic transducers
Authors: Na Yonghyeon , Lee Min-Seon , Park Woon-Ik , Lee Jung Woo , Jeong Young Hun
Published: June 2020

An air-coupled piezoelectric ultrasonic transducer (PUT) was fabricated to assess the effects of a nano-scale embossed Al diaphragm on the acoustic emission characteristics. A 310-μm-thick multilayer piezoelectric film and a 300-μm-thick Al plate were used for the PUT. It was found that the flexural modulus of the Al plate was decreased slightly from 3.73 GPa to 3.41 GPa by the effect of the embossed surface morphology, having an array of Al bumps with dimensions of 800 nm × 800 nm and a height of 320 nm. The decreased flexural modulus had a strong effect on the decrement of the acoustic resonant frequency and on the enhancement of the sound power radiation for the PUT. In comparison to a sound pressure level (SPL) of 117.8 dB at 30 cm away from a flat PUT at 41.4 kHz, the embossed PUT could result in a significantly enhanced SPL of 121.7 dB at the secondary resonant frequency of 40.5 kHz for the implementation of a smaller transducer. This result can motivate an efficient design parameter for better performance of a PUT through modifications of the nm-scale embossed surface.
Variations in Duschinsky rotations in m-fluorotoluene and m-chlorotoluene during excitation and ionization
Authors: Davies Alexander R. , Kemp David J. , Warner Lewis G. , Fryer Elizabeth F. , Rees Alan , Wright Timothy G.
Published: June 2020

We investigate Duschinsky rotation/mixing between three vibrations for both m-fluorotoluene (mFT) and m-chlorotoluene (mClT), during electronic excitation and ionization. In the case of mFT, we investigate both the S1 → S0 electronic transition and the D0+ ← S1 ionization, by two-dimensional laser-induced fluorescence (2D-LIF) and zero-electron-kinetic energy (ZEKE) spectroscopy, respectively; for mClT, only the D0+ ← S1 ionization was investigated, by ZEKE spectroscopy. The Duschinsky mixings are different in the two molecules, owing to shifts in vibrational wavenumber and variations in the form of the fundamental vibrations between the different electronic states. There is a very unusual behavior for two of the mFT vibrations, where apparently different conclusions for the identity of two S1 vibrations arise from the 2D-LIF and ZEKE spectra. We compare the experimental observations to the calculated Duschinsky matrices, finding that these successfully pick up the key geometric changes associated with each electronic transition and so are successful in qualitatively explaining the vibrational activity in the spectra. Experimental values for a number of vibrations across the S0, S1, and D0+ states are reported and found to compare well to those calculated. Assignments are made for the observed vibration-torsion (“vibtor”) bands, and the effect of vibrational motion on the torsional potential is briefly discussed.
Competition of Dexter, Förster, and charge transfer pathways for quantum dot sensitized triplet generation
Authors: Jin Tao , Uhlikova Natalie , Xu Zihao , Zhu Yifan , Huang Yiming , Egap Eilaf , Lian Tianquan
Published: June 2020

Quantum dot (QD) sensitized triplet exciton generation has demonstrated promising applications in various fields such as photon up-conversion through triplet–triplet annihilation. However, how direct triplet energy transfer from the QD to the acceptor through Dexter energy transfer (DET) competes with other processes, including Förster resonance energy transfer (FRET) and charge transfer, remains poorly understood. Herein, the competition of these pathways for QD-sensitized triplet excited state generation in CdSe QD-modified boron dipyrromethene (BODIPY) complexes is studied using transient absorption spectroscopy. After excitation of the CdSe QD with 500 nm pulses, the BODIPY triplet excited state is generated through charge recombination in a charge separated intermediate state (QD−·–BODIPY+·). This intermediate state is populated either through FRET from the excited QD to BODIPY followed by electron transfer from the singlet excited state of BODIPY to the QD or through hole transfer from the excited QD to BODIPY. The triplet excited state generation efficiencies from the FRET and hole transfer pathways are estimated to be (6.18 ± 1.39)% and (13.5 ± 3.1)%, respectively. Compared to these indirect pathways, direct DET from the QD to the BODIPY triplet state is kinetically not competitive. These results demonstrate that sequential charge transfer can be an efficient pathway for triplet excited state generation in QD–acceptor complexes.
An efficient selective cell-based smoothed finite element approach to fluid-structure interaction
Authors: He Tao
Published: June 2020

This paper describes an efficient and simple selective cell-based smoothed finite element method (CS-FEM) for partitioned fluid–structure interaction. Depending on a fractional-step fluid solver, a selective smoothed integration scheme is proposed for the Navier–Stokes equations in stationary and deforming domains. A simple hourglass stabilization is then introduced into the under-integrated smoothed Galerkin weak form of the fractional-step algorithm. As a result, the computational efficiency is considerably boosted in comparison with existing CS-FEM formulation. Meanwhile, the CS-FEM is applied to spatially discretize the elastodynamics equations of nonlinear solids as usual. After discussing the mesh moving strategy, the gradient smoothing is performed in each individual interface element to evaluate the fluid forces acting on oscillating rigid and flexible bodies. The block Gauss–Seidel procedure is employed to couple all interacting fields under the arbitrary Lagrangian–Eulerian description. Several numerical examples are presented to demonstrate the desirable efficiency and accuracy of the proposed methodology.
Magnetization switching by nanosecond pulse of electric current in thin ferrimagnetic film near compensation temperature
Authors: Yurlov V. V. , Zvezdin K. A. , Kichin G. A. , Davydova M. D. , Tseplina A. E. , Hai Ngo Trong , Wu Jong-Ching , Ciou Sheng-Zhe , Chiou Yi-Ru , Ye Lin-Xiu , Wu Te-Ho , Bhatt Ramesh Chandra , Zvezdin A. K.
Published: June 2020

We report on a theoretical study of thermal magnetization switching induced by nanosecond electric current pulse using Lagrangian formalism based on the Landau–Lifshitz–Gilbert equation. The parameters for modeling are obtained from the measurements of the anomalous Hall resistance at different probe currents. We obtain the switching diagrams, analyze how the switching rate depends on the pulse parameters and the applied magnetic field, and find the optimal set of values such as orientation of the field, electric pulse duration, and energy consumption. We find that the magnetization switching is particularly efficient near the compensation point, where a decrease in the magnetization of the rare-earth sublattices by 10% or less can lead to reversal of net magnetization.
Droplet dynamics on viscoelastic soft substrate: Toward coalescence control
Authors: Leong Fong Yew , Le Duc-Vinh
Published: June 2020

We study the dynamical behavior of droplets on a viscoelastic soft substrate. Using thin film approximation for the hydrodynamics and time-dependent Winkler’s substrate model, we show numerically how droplet growth depends strongly on the viscous damping characteristic of the substrate, leading to asymmetric stick-slip dynamics corroborated by experimental observations. Scaling arguments are presented to rationalize radial growth and the underlying substrate response to viscoelastic limits. Using an adjacent pair of inflating droplets, we report strongly diverse coalescence outcomes with non-linear coalescence times, including attraction, repulsion, and remarkably, a separation regime, within which the two droplets grow away from each other and remain separated due to intervening wetting ridges. Together, our results indicate strong interactions between the substrate and the droplet across viscoelastic and capillary timescales, with practical implications for smart surface engineering, condensation, and coalescence control.
Exploration and prediction of fluid dynamical systems using auto-encoder technology
Authors: Agostini Lionel
Published: June 2020

Machine-learning (ML) algorithms offer a new path for investigating high-dimensional, nonlinear problems, such as flow-dynamical systems. The development of ML methods, associated with the abundance of data and combined with fluid-dynamics knowledge, offers a unique opportunity for achieving significant breakthroughs in terms of advances in flow prediction and its control. The objective of this paper is to discuss some possibilities offered by ML algorithms for exploring and predicting flow-dynamical systems. First, an overview of basic concepts underpinning artificial neural networks, deep neural networks, and convolutional neural networks is given. Building upon this overview, the concept of Auto-Encoders (AEs) is introduced. An AE constitutes an unsupervised learning technique in which a neural-network architecture is leveraged for determining a data structure that results from reducing the dimensionality of the native system. For the particular test case of flow behind a cylinder, it is shown that combinations of an AE with other ML algorithms can be used (i) to provide a low-dimensional dynamical model (a probabilistic flow prediction), (ii) to give a deterministic flow prediction, and (iii) to retrieve high-resolution data in the spatio-temporal domain from contaminated and/or under-sampled data.
Transportable atomic clocks achieve laboratory precision
Authors: Middleton Christine
Published: June 2020

When deployed in field-based experiments, the devices could improve timekeeping standards and test fundamental physics.
Fruit photonics and the shape of water
Authors: Slepkov Aaron
Published: June 2020

To microwaves, grapes are resonant, spherical blobs of water.
Health today versus health tomorrow: does Australia really care less about its future health than other countries do?
Authors: Devlin Nancy , Scuffham Paul
Published: June 2020

Economic evaluation provides important evidence on value for money in health care and is routinely used in health technology assessment processes. The relevant costs and benefits of health care that are considered may arise now and/or in the future, and the relative importance placed on costs and benefits in the future is reflected in the discount rate applied to them. In this paper we note that Australia appears to apply one of the highest discount rates in the world to the assessment of future healthcare benefits. At a time when healthcare systems worldwide are calling for a rebalance of effort towards prevention, Australia’s discount rate risks pulling resource allocation in precisely the opposite direction, locking in institutional short-sightedness to funding decisions.
Expression of enzymes involved in polyunsaturated fatty acid synthesis in the stallion testis and epididymis
Authors: Gautier Camille , Scarlet Dragos , Ertl Reinhard , Walter Ingrid , Wulf Manuela , Nagel Christina , Aurich Jörg , Aurich Christine
Published: June 2020

The aim of the present study was to characterise key enzymes involved in polyunsaturated fatty acid (PUFA) synthesis in the testis and epididymis collected from 2-year-old healthy warmblood stallions (n=10). The mRNA expression of fatty acid synthase, the Δ9-, Δ6-, Δ5- and Δ4-desaturases and elongases 6, 5 and 2 (encoded by the fatty acid synthase (FASN), the stearoyl-CoA desaturase (SCD), the fatty acid desaturase 2 (FADS2), the fatty acid desaturase 1 (FADS1), the delta 4-desaturase, sphingolipid 1 (DEGS1), ELOVL fatty acid elongase 6(ELOVL6), ELOVL fatty acid elongase 5 (ELOVL5), ELOVL fatty acid elongase 2 (ELOVL2) genes respectively) was determined in equine testis and epididymis. All enzymes were present in testicular tissue and along the epididymis, but mRNA expression differed among localisations. The protein localisation of FADS1, FADS2 and ELOVL5 was determined by immunohistochemistry. In the testes, FADS1 was expressed in the germinal cells and ELOVL5 was expressed in germinal and Leydig cells; FADS2 was not detected. In the epididymis, FADS1 and FADS2 were expressed in the principal and basal cells, whereas ELOVL5 was found only in the principal cells of the caput. All three enzymes were present in epididymal vesicles secreted by an apocrine mechanism. These results suggest active PUFA metabolism during spermatogenesis and epididymal sperm maturation in stallions.
Pied-piping in degree wh-clauses in Spanish
Authors: Eguren Luis , Pastor Alberto
Published: June 2020

This paper presents a novel analysis of (non)-pied-piping structures in degree wh-clauses with adjectives in Spanish based on the idea in Heck (2008, 2009) that optional pied-piping cannot exist. Under this assumption, it is argued that pied-piping and non-pied-piping structures in the constructions under study originate from two different structures: pied-piping structures obtain from a standard structural configuration in which the degree wh-form heads a functional phrase in the extended projection of the adjective, whereas the discontinuous structure with cómo de ‘how of’ ([cómo … de+A]) results from a reanalysis process turning de+A into a verbal adjunct. This analysis is extended to related constructions both in Spanish and in other Romance languages, and some apparent counterexamples are also discussed.
Developing epistemic meaning
Authors: Jarrett Dylan
Published: June 2020

The present paper focuses on the development of the Spanish adverb a lo mejor, originally meaning ‘to the best’ as it develops from a prepositional phrase indicating a destination or goal to an epistemic modal adverb which expresses the speaker’s doubt concerning the proposition. It is shown that the semantic change came about due to a combination of local and contextual factors. Chief among them is the pre-verbal positioning of a lo mejor, its occurrence with achievement predicates, and implications of futurity. In becoming an epistemic adverb, the change follows Traugott’s Tendency III for semantic change which states that “meanings tend to become increasingly based in the speaker’s subjective belief state/attitude toward the proposition” (1989, p. 35).
The acquisition of personal a among Chinese-speaking L2 learners of Spanish
Authors: Jiao Jian , Cuza Alejandro , López Otero Julio César
Published: June 2020

The present study examines the acquisition of differential object marking (dom) in Spanish among Mandarin-speaking L2 learners from China. Unlike Mandarin, which marks the direct object only in preverbal position (i.e., in SOV sentences) and is a topic-prominent language, Spanish allows dom in both simple and clitic left-dislocated (CLLD) sentences. We predicted L2 learners to have more difficulty with CLLD structures than with simple sentences due to structural complexity issues. Results from an Elicited Production task showed target-like performance in simple sentences among the L2 learners but overextension of the a-marker to contexts where it is not required in CLLD structures. The results are discussed along the lines of previous work on the effects of crosslinguistic influence and structural complexity.
Catching identitiesin flight
Authors: Jacobs Catho , Mieroop Dorien Van De , Laar Colette Van
Published: June 2020

We present a case study of a small talk sequence in a Belgian workplace between two female colleagues with a migration background, in which they share stories with each other on racial micro-aggressions they personally experienced. We draw on the social practice approach and focus on the narrators’ identity work in this interaction. We found that the narrators construct stories in which powerless and outgroup identities are projected upon them in the storyworld, but by means of which more empowered identities and an ingroup with the interlocutor are talked into being in the storytelling world. Interestingly, these findings can be linked to the rejection-identification dynamic. This social psychological model shows that individuals who experienced discrimination are able to buffer negative consequences to their psychological well-being by identifying with the group that is discriminated against. This article adds to this earlier research by showing the crucial role of language, in particular of storytelling and small talk, in this rejection-identification dynamic.
Regional varieties in Norway revisited
Authors: Røyneland Unn
Published: June 2020

This chapter examines diverging tendencies towards vertical convergence in different parts of Norway and patterns of emergence and enregisterment of intermediate regional varieties – at the level of language use, but particularly at the level of perception. Over the last decades the Norwegian language space has undergone substantial restructuring, partly due to increasing mobility, urbanisation and globalisation. More dialect and language contact has led to increased dialect levelling, dialect shift, bi-dialectism, emergence of koinai, multiethnolectal speech styles and possibly also intermediate regional varieties. While previous studies suggest that regional lects may be emerging, this paper presents arguments on the basis of results from a recent large-scale study, as well as other recent work, to the effect that these still seem to remain structurally relatively incoherent, unfocussed and unstable and have little indexical value or symbolic significance.
Reduction and persistence of phonological dialect features in German
Authors: Schwarz Christian
Published: June 2020

Like in most European speech communities, the loss of rural dialects and the emergence of regional varieties could also be observed within the German speaking area since at least the 19th century. Previous research on mechanisms influencing the selection process of dialect features was mainly carried out on a theoretical level. This paper aims at contributing an empirical component by presenting the results of a study with focus on selection mechanisms of phonological dialect features in southwest Germany. It will be argued that similarity to the standard, geographical spread, grammatical function and frequency are factors of major importance regarding the chance of survival of dialect features during their transition from rural dialects to regional standard contexts. Of the seven phonological phenomena analysed, in the end only one clearly remains: /s/-palatalisation. Interestingly, this feature does not necessarily possess positive social salience, but is apparently hard to abandon for speakers from the Southwest.
Variation, identity and indexicality in southern Spanish
Authors: Villena-Ponsoda Juan-Andrés , Vida-Castro Matilde
Published: June 2020

The aim of this chapter is to claim that the emergence of a new intermediate variety in the space between standard Castilian Spanish and vernacular varieties from Andalusia is based on a new identity that blends, on the one hand, the individual’s orientation towards modern life, urbanisation and standardness and, on the other hand, faithfulness to the southern traditional community values. In fact, linguistic features shaping this intermediate variety – including split of southern consonant mergers and preservation of the southern erosive changes affecting consonants in coda position – go far beyond phonology and correlate in such a way that it is conceivable to assume the existence of a socially and perceptually coherent variety that can be considered as an alternative to the regional standard from Seville. To prove this, multivariate analyses of phonological, morphological, syntactic and lexical variables have been carried out in the context of a research project including southern (Granada, Malaga, Seville) and central (Madrid) urban areas. Results confirm that this variety is mainly spoken by young urban middle-class standard-oriented speakers who do not identify with the traditional southern way of life.1
Survival of the ‘oddest’?
Authors: Tsiplakou Stavroula , Armostis Spyros
Published: June 2020

This contribution examines some cases of arrested convergence to the standard variety in Cypriot Greek, the ‘L’ variety in Cyprus’ diglossic context; we explore some of the reasons why full convergence of the Cypriot Greek koine to Standard Greek does not take place and why certain dialect features which are marked and/or perceived as ‘odd’ or exceptional have found their way into the koine. The paper presents quantitative findings from rating surveys and elicitation tasks targeting phonological, syntactic and semantic phenomena: (1) the predominance of clefting, the Cypriot strategy for syntactic focusing, in lieu of focus movement, the Standard Greek strategy for syntactic focusing; (2) the semantic and pragmatic properties of innovative Past Perfect, which suggest that it is construed as a bona fide Cypriot Greek [+past] tense, despite morphological and phonological innovation; (3) the survival and spread of variants such as the palatal [ʝː] in lieu of the standard-like [ʎː], or the preservation of old ones, a typical case being the shibbolethal, basilectal [ç]. The data highlight the intricate interplay of structural and sociolinguistic factors, which attests to the complexity of the processes of koine formation.
Metabolism of airborne methyl salicylate in adjacent plants
Authors: Masimbula Rishni , Oki Katsunari , Takahashi Kosaku , Matsuura Hideyuki
Published: June 2020

Salicylic acid (SA) and methyl salicylate (MeSA) are synthesized in many plants and are crucial components that establish their disease responses. The metabolism of airborne MeSA to SA has been previously reported. In this report, it was found that SA glucose ester (SAGE), ether (SAG), and salicyloyl-l-aspartic acid (SA-Asp) are metabolites of airborne MeSA. Furthermore, it was found that airborne MeSA was able to increase the endogenous amount of rosmarinic acid in Perilla frutescens, which is known as one of the functional components that contributes to the maintenance of human health.
In situ cryo-electron tomography reveals filamentous actin within the microtubule lumen
Authors: Paul Danielle M. , Mantell Judith , Borucu Ufuk , Coombs Jennifer , Surridge Katherine J. , Squire John M. , Verkade Paul , Dodding Mark P.
Published: June 2020

Microtubules and filamentous (F-) actin engage in complex interactions to drive many cellular processes from subcellular organization to cell division and migration. This is thought to be largely controlled by proteins that interface between the two structurally distinct cytoskeletal components. Here, we use cryo-electron tomography to demonstrate that the microtubule lumen can be occupied by extended segments of F-actin in small molecule–induced, microtubule-based, cellular projections. We uncover an unexpected versatility in cytoskeletal form that may prompt a significant development of our current models of cellular architecture and offer a new experimental approach for the in situ study of microtubule structure and contents.
An energy time-convexity second-order synchrosqueezing transform and application in weak fault diagnosis of rolling bearings in an aerospace engine
Authors: Chen Zhenyi , Zi Yanyang , Li Ping , Chen Jinglong , Xu Kaifu
Published: June 2020

Although the original short-time Fourier-transform-based synchrosqueezing transform (FSST) and its second-order transform (FSST2) can effectively improve the readability of quasi-stationary signal and time-varying signal, respectively, the weak components of time–frequency representation are often submerged easily by noises and large-amplitude instantaneous frequencies (IFs). Moreover, aerospace engines always work in fierce vibration and non-steady states, and this easily causes the weak fault feature of rolling bearings obscured in the time–frequency domain. To solve this problem, we propose a time–frequency analysis algorithm called energy time-convexity second-order synchrosqueezing transform (ET-FSST2). This can sharpen the time-varying IFs like FSST2, and more importantly, it can extract the time-varying IFs with small amplitudes such as weak impulse-like components from multi-component vibration signals. The ET-FSST2 firstly calculates the energy convexity function in the time direction to extract the non-stationary IFs after employing FSST2. It then structures an optimization function by combining a hyperbolic tangent function with a chi-square distribution function as well as optimizing the targeted parameters, aiming to extract the weak components of the non-stationary IFs. Moreover, the effectiveness and robustness of the proposed method are validated by numerical simulation and rolling bearing fault tests. Finally, two case studies of weak fault diagnosis of Ni–Cu–Ag-based PVD-coated rolling bearings operating in cryogenic surroundings are given to illustrate the effectiveness of the proposed method for aerospace engine bearing fault diagnosis.
Free electron laser generation of x-ray Poincaré beams
Authors: Morgan Jenny , Hemsing Erik , McNeil Brian W J , Yao Alison
Published: June 2020

An optics-free method is proposed to generate x-ray radiation with spatially variant states of polarization via an afterburner extension to a free electron laser. Control of the polarization in the transverse plane is obtained through the overlap of different coherent transverse light distributions radiated from a bunched electron beam in two consecutive orthogonally polarised undulators. Different transverse profiles are obtained by emitting at a higher harmonic in one or both of the undulators. This method enables the generation of beams structured in their intensity, phase, and polarization—so-called Poincaré beams—at high powers with tunable wavelengths. Simulations are used to demonstrate the generation of two different classes of light with spatially inhomogeneous polarization—cylindrical vector beams and full Poincaré beams.
Preparation and study of Polyvinyl Alcohol/Attapulgite nanocomposite fibers with high strength and high Young’s modulus by gel spinning
Authors: Hong Xinqiu , Zou Liming , Xu Yongjing , Li Yan Vivian , He Junwei
Published: June 2020

Polyvinyl alcohol (PVA)/Attapulgite (ATT) nanocomposite fibers with high strength and high Young’s modulus were prepared via gel spinning. The structures and properties of PVA/ATT nanocomposite fibers were investigated with Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimeter (DSC), thermo gravimetric analysis (TGA), x-ray diffraction (XRD), Environmental scanning electron microscope (ESEM), and mechanical testing. The results showed that ATT had a great influence on the structures and properties of PVA/ATT nanocomposite fibers. The melting temperatures, crystallinities, initial decomposition temperatures and maximum decomposition temperatures of PVA/ATT nanocomposite fibers increased firstly when ATT content was increased from zero to 3 wt%, however, they were then dropped when ATT contents were 5 wt% and 7 wt%. The highest melting temperature, crystallinity, initial decomposition temperature and maximum decomposition temperature of PVA/ATT-3 were 240.4 °C, 67.6%, 266.7 °C and 358.6 °C, respectively. Furthermore, ESEM observation indicated that ATT had good adhesion to PVA matrix. Mechanical tests showed that PVA/ATT-3 had the highest breaking tensile and Young’s modulus of 12.6 cN/dtex and 301.9 cN/dtex, respectively.
InxGa1−xSe mixed crystals grown from an In flux by the traveling heater method for THz wave generation
Authors: Sato Yohei , Tang Chao , Watanabe Katsuya , Ohsaki Junya , Yamamoto Takuya , Tanabe Tadao , Oyama Yutaka
Published: June 2020

The growth rate of crystalline GaSe from solution was increased by using indium as a solvent. The solubility and concentration gradient of Se were measured using differential scanning calorimetry (DSC). The Se solubility and the temperature coefficient of the solubility were respectively 15 times and 2.2 times greater in crystals grown from an In flux with GaSe at saturation compared with the case of Se dissolved in a Ga flux. In this study, we succeeded in growing InxGa1−xSe ingots from an In flux without the need for a seed crystal, and in increasing the growth rate of GaSe from solution. In addition, we used difference frequency generation to generate THz waves (with a frequency of 9.7 THz) in an InxGa1−xSe mixed crystal and investigated the relationship between the output energy of the THz radiation and the interaction length of the excitation light. The conversion efficiency of THz wave (9.7 THz) from the InxGa1−xSe mixed crystal with thickness of 860 μm was 26 times greater than that of GaSe crystal with thickness 100 μm grown from Ga solvent.
Drainage reduces the resilience of a boreal peatland
Authors: Harris Lorna I , Roulet Nigel T , Moore Tim R
Published: June 2020

Drier conditions caused by drainage for infrastructure development, or associated with global climate warming, may test the resilience of carbon-rich northern peatlands. Feedbacks among biological and hydrological processes maintain the long-term stability of peatlands, but if hydrological thresholds are passed, these feedbacks may be weakened, causing a shift in ecosystem state and potentially large losses of carbon (C). To determine peatland response to hydrological change, we examined the structure (vegetation composition and hydrology) and biogeochemical function (carbon dioxide exchange) of a pristine bog and a bog subject to ∼7 years localised drainage (caused by regional groundwater drawdown due to mine dewatering) in the Hudson Bay Lowland, Canada. Water tables at the drained bog were ∼1 m below the hummock surface at the time of study compared to ∼0.3 m at the pristine bog. For hummocks and intermediate microforms at the drained bog, plant production was significantly less than at the pristine bog, most likely due to small changes in vegetation structure (reduced Sphagnum cover and smaller shrub leaf:stem ratios) caused by deeper water tables and significantly reduced moisture content of surface peat. Despite these changes in vegetation and hydrology, net ecosystem production (NEP) remained positive (C sink) for these microforms at the drained bog. Dry pools with mostly bare peat at the drained bog had negative NEP (C source to atmosphere), in stark contrast to Sphagnum- and sedge-dominated pools at the pristine bog with small but positive NEP. Our study shows that dry pools now occupy an unstable state, but the hydrological thresholds for a shift in ecosystem state have not yet been reached for hummocks and intermediate microforms at the drained bog. However, weak or no relationships between water table depth, peat surface moisture content, and plant production for these microforms at the drained bog, suggest that drainage has weakened the hydrological feedbacks regulating peat production, causing peat accumulation to slow. If drier conditions prevail, this reduced resilience increases the potential for a shift in ecosystem state and raises the risk of large C loss due to continued decomposition of deeper peat in oxic conditions, and wildfire.
Randomized CP tensor decomposition
Authors: Erichson N Benjamin , Manohar Krithika , Brunton Steven L , Kutz J Nathan
Published: June 2020

The CANDECOMP/PARAFAC (CP) tensor decomposition is a popular dimensionality-reduction method for multiway data. Dimensionality reduction is often sought after since many high-dimensional tensors have low intrinsic rank relative to the dimension of the ambient measurement space. However, the emergence of ‘big data’ poses significant computational challenges for computing this fundamental tensor decomposition. By leveraging modern randomized algorithms, we demonstrate that coherent structures can be learned from a smaller representation of the tensor in a fraction of the time. Thus, this simple but powerful algorithm enables one to compute the approximate CP decomposition even for massive tensors. The approximation error can thereby be controlled via oversampling and the computation of power iterations. In addition to theoretical results, several empirical results demonstrate the performance of the proposed algorithm.
The influence of sorbitol doping on aggregation and electronic properties of PEDOT:PSS: a theoretical study
Authors: Friederich Pascal , León Salvador , Perea José Darío , Roch Loïc M , Aspuru-Guzik Alán
Published: June 2020

Many organic electronics applications such as organic solar cells or thermoelectric generators rely on PEDOT:PSS as a conductive polymer that is printable and transparent. It was found that doping PEDOT:PSS with sorbitol enhances the conductivity through morphological changes. However, the microscopic mechanism is not well understood. In this work, we combine computational tools with machine learning to investigate changes in morphological and electronic properties of PEDOT:PSS when doped with sorbitol. We find that sorbitol improves the alignment of PEDOT oligomers, leading to a reduction of energy disorder and an increase in electronic couplings between PEDOT chains. The high accuracy (r
2 > 0.9) and speed up of energy level predictions of neural networks compared to density functional theory enables us to analyze HOMO energies of PEDOT oligomers as a function of time. We find a surprisingly low degree of static energy disorder compared to other organic semiconductors. This finding might help to better understand the microscopic origin of the high charge carrier mobility of PEDOT:PSS in general and potentially help to design new conductive polymers.
Leaf traits and performance vary with plant age and water availability in Artemisia californica
Authors: Funk Jennifer L , Larson Julie E , Vose Gregory
Published: June 2020

Background and Aims

Leaf functional traits are strongly tied to growth strategies and ecological processes across species, but few efforts have linked intraspecific trait variation to performance across ontogenetic and environmental gradients. Plants are believed to shift towards more resource-conservative traits in stressful environments and as they age. However, uncertainty as to how intraspecific trait variation aligns with plant age and performance in the context of environmental variation may limit our ability to use traits to infer ecological processes at larger scales.

Methods

We measured leaf physiological and morphological traits, canopy volume and flowering effort for Artemisia californica (California sagebrush), a dominant shrub species in the coastal sage scrub community, under conditions of 50, 100 and 150 % ambient precipitation for 3 years.

Key Results

Plant age was a stronger driver of variation in traits and performance than water availability. Older plants demonstrated trait values consistent with a more conservative resource-use strategy, and trait values were less sensitive to drought. Several trait correlations were consistent across years and treatments; for example, plants with high photosynthetic rates tended to have high stomatal conductance, leaf nitrogen concentration and light-use efficiency. However, the trade-off between leaf construction and leaf nitrogen evident in older plants was absent for first-year plants. While few traits correlated with plant growth and flowering effort, we observed a positive correlation between leaf mass per area and performance in some groups of older plants.

Conclusions

Overall, our results suggest that trait sensitivity to the environment is most visible during earlier stages of development, after which intraspecific trait variation and relationships may stabilize. While plant age plays a major role in intraspecific trait variation and sensitivity (and thus trait-based inferences), the direct influence of environment on growth and fecundity is just as critical to predicting plant performance in a changing environment.
Below-ground competition alters attractiveness of an insect-pollinated plant to pollinators
Authors: Flacher Floriane , Raynaud Xavier , Hansart Amandine , Geslin Benoît , Motard Eric , Verstraet Séléné , Bataille Manon , Dajoz Isabelle
Published: June 2020

Competitive interactions between plants can affect patterns of allocation to reproductive structures through modulation of resource availability. As floral traits involved in plant attractiveness to pollinators can be sensitive to these resources, competition with any neighbouring species may influence the attractiveness of insect-pollinated plants. While pollination research has primarily focused on above-ground interactions, this study aims at investigating if the presence of a competitor plant can modulate neighbouring insect-pollinated plant attractiveness to pollinators and resulting fecundity, especially through below-ground competitive interactions for soil resources. We set up a plot experiment in which we grew an insect-pollinated plant, Sinapis alba (Brassicaceae), in a mixture dominated by a wind-pollinated plant, Holcus lanatus (Poaceae). Individuals of S. alba were either subjected to or isolated from (with buried tubes in the soil) below-ground competition. Across the flowering season, floral traits involved in attractiveness of S. alba and pollinator visitation were followed at the plot and plant level to investigate different scales of attractiveness. At the end of the experiment, seeds were harvested to assess plant fecundity. Competition had a significant negative effect on plot and plant floral display size as well as flower size while nectar traits were not affected. When plants of S. alba were in competition, the time to first visit was altered: the proportion of plots that received a visit was smaller for a given time; in other words, it took more time for a given proportion of plots to be visited and some plots were even never visited. Moreover, pollinators made fewer visits per plots. The proportion of viable seeds produced by S. alba in competition was lower and probably linked to the competition itself rather than changes in pollinator visitation. This study suggests that competitive interactions between plants can modulate pollination interactions even when competing plant species are not insect-pollinated.
Deferiprone Stimulates Aged Dermal Fibroblasts via HIF-1α Modulation
Authors: Pagani Andrea , Kirsch B Manuela , Hopfner Ursula , Aitzetmueller Matthias M , Brett Elizabeth A , Thor Dominik , Mela Petra , Machens Hans-Guenther , Duscher Dominik
Published: June 2020

Background

Hypoxia-inducible factor 1α (HIF-1α), a transcription factor responsible for tissue homeostasis and regeneration, presents reduced functionality in advanced age. In addition to absence of oxygen, sequestration of iron also stimulates HIF-1α. Therefore, we analyzed the efficacy of the iron-chelator deferiprone (DFP) at stimulating dermal fibroblasts.

Objectives

The main objective of this study was to quantify the DFP concentrations capable of stimulating dermal fibroblasts in vitro and to correlate the effective DFP concentrations with the ability of DFP to penetrate the epidermis, reach the dermis, and activate HIF-1α in vivo.

Methods

We measured cell proliferation, metabolic activity, HIF-1α expression, and lactate dehydrogenase levels of both young and aged fibroblasts after a 24-hour in vitro preconditioning with DFP. In addition, we evaluated cell survival rates and morphology with different cellular stainings. Finally, we performed a transdermal permeation study with a 1% DFP topical formulation to quantify the concentration required to reach the dermis.

Results

In vitro administration of iron-chelation therapy (156-312.5 µg/mL DFP ) on aged fibroblasts resulted in activation of various antiaging processes. The concentration required to reach the dermis within 24 hours was 1.5% (0.15 mg/mL), which corresponds well with the effective doses of our laboratory analyses.

Conclusions

The activation of HIF-1α by DFP enhances cell metabolism, proliferation, and survival of fibroblasts while reducing lactate dehydrogenase levels. Modulation of HIF-1α is linked to activation of key regeneration enzymes and proteins, and by proxy, antiaging. Therefore, the antiaging properties of DFP and its satisfactory dermal penetration make it a promising regenerative agent.