bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuromorphic computing with antiferromagnetic spintronics
Authors: Kurenkov Aleksandr , Fukami Shunsuke , Ohno Hideo
Published: July 2020

While artificial intelligence, capable of readily addressing cognitive tasks, has transformed technologies and daily lives, there remains a huge gap with biological systems in terms of performance per energy unit. Neuromorphic computing, in which hardware with alternative architectures, circuits, devices, and/or materials is explored, is expected to reduce the gap. Antiferromagnetic spintronics could offer a promising platform for this scheme. Active functionalities of antiferromagnetic systems have been demonstrated recently and several works indicated their potential for biologically inspired computing. In this perspective, we look through the prism of these works and discuss prospects and challenges of antiferromagnetic spintronics for neuromorphic computing. Overview and discussion are given on non-spiking artificial neural networks, spiking neural networks, and reservoir computing.
Study on helium atmospheric pressure plasma jet using collisional-radiative model
Authors: Lee Wonwook , Tran Tuyen Ngoc , Oh Cha-Hwan
Published: July 2020

The helium (He) non-thermal atmospheric pressure plasma jet (APPJ) source was configured, and the He spectra were measured by applying AC power to the source. A He collisional-radiative (CR) model was developed to investigate the He spectra obtained from the APPJ source. Different atmospheric pressure (AP) processes were evaluated, and the dominant processes among them that contribute to the He spectra were determined. The plasma parameters of the APPJ were determined using the He CR model, and the He spectra were successfully reproduced. The electron density was determined to be ∼2×1012 cm−3 between the electrodes of the APPJ, and ∼9×1011cm−3 outside the quartz tube, for a frequency and bias of an AC voltage source of 5 kHz and 10 kVp.p, respectively. A parametric study was performed to explain the behavior of the electron temperature and electron density of APPJ.
Dual crystallization modes of sputter-deposited amorphous SiGe films
Authors: Okugawa M. , Nakamura R. , Numakura H. , Ishimaru M. , Yasuda H.
Published: July 2020

The crystallization behavior of sputter-deposited films of amorphous Si (a-Si) and SiGe alloys (a-SiGe) induced by electron irradiation at room temperature and by thermal annealing was investigated by in situ transmission electron microscopy. On electron irradiation at room temperature, extremely rapid crystallization, so-called explosive crystallization, occurred at a higher electron flux but not at a lower electron flux. On in situ thermal annealing, explosive crystallization occurred preferentially and partially at low temperatures in Ge-rich a-SixGe100−x for x < 50 but not for x > 50. These results indicate that the increase of Si content in a-SiGe prevents the occurrence of explosive crystallization. We previously proposed that explosive crystallization can occur in pristine a-Ge films via the interface of a liquid-like, high-density amorphous state at the growth front. An increase in the instability of this high-density amorphous state caused by the increase of Si in a-SiGe apparently gives rise to the suppression of explosive crystallization.
Precipitation of calcium–alumino–silicate–hydrate gels: The role of the internal stress
Authors: Zhao Cheng , Zhou Wei , Zhou Qi , Zhang Yao , Liu Han , Sant Gaurav , Liu Xinghong , Guo Lijie , Bauchy Mathieu
Published: July 2020

Concrete gains its strength from the precipitation of a calcium–alumino–silicate–hydrate (C–A–S–H) colloidal gel, which acts as its binding phase. However, despite concrete’s ubiquity in the building environment, the atomic-scale mechanism of C–A–S–H precipitation is still unclear. Here, we use reactive molecular dynamics simulations to model the early-age precipitation of a C–A–S–H gel. We find that, upon gelation, silicate and aluminate precursors condensate and polymerize to form an aluminosilicate gel network. Notably, we demonstrate that the gelation reaction is driven by the existence of a mismatch of atomic-level internal stress between Si and Al polytopes, which are initially experiencing some local tension and compression, respectively. The polymerization of Si and Al polytopes enables the release of these competitive stresses.
Asymmetric spin relaxation induced by residual electron spin in semiconductor quantum-dot-superlattice hybrid nanosystem
Authors: Hiura Satoshi , Hatakeyama Saeko , Takayama Junichi , Murayama Akihiro
Published: July 2020

Asymmetric spin relaxation induced by the residual electron spin in semiconductor quantum dots (QDs) adjacent to a superlattice (SL) was studied using spin- and time-resolved photoluminescence under the selective photoexcitation of the SL miniband states. Spin-polarized electrons were photoexcited in the SL barrier and then injected into the QDs through spin-conserving tunneling. The spin-polarized electron transport and the faster transport of the electrons as compared to the holes generate the residual majority electron spins in the QDs. A reversal of the optical spin polarity was observed at the ground state of the QDs, depending on the excitation powers. A rate equation analysis considering the individual spin-flip times between spin-split QD states indicates that the polarity reversal originates from the asymmetric spin-flip process at the excited state of the QDs. The asymmetric spin relaxation is associated with the selective relaxation of the spin-flipped electron and hole to the unoccupied ground state, which is induced by the existence of the residual majority electron spin at this state. In addition, we observed a clear recovery of the optical spin polarity by eliminating the existence of the residual electron spin through heavy p-doping. These findings are important to attain a fundamental understanding of the spin relaxation mechanism within the QDs and provide an insight into the manipulation of the optical spin polarity by controlling the residual electron spins in the QDs.
Amplitudes of minima in dynamic conductance spectra of the SNS Andreev contact
Authors: Popović Z. , Kuzmichev S. , Kuzmicheva T.
Published: July 2020

Although several theoretical approaches describing multiple Andreev reflection (MAR) effects in the superconductor–normal metal–superconductor (SNS) junction are elaborated, the problem of the comprehensive and adequate description of MAR is highly actual. In particular, a broadening parameter Γ is still unaccounted at all, whereas a ballistic condition (the mean free path for inelastic scattering l to the barrier width d ratio) is considered only in the framework of Kümmel, Gunsenheimer, and Nikolsky (KGN), as well as Gunsenheimer–Zaikin approaches, for an isotropic case and fully transparent constriction. Nonetheless, the influence of the l/d ratio on the dynamic conductance spectrum (dI/dV) features remains disregarded, thus being one of the aims of the current work. Our numerical calculations in the framework of an extended KGN approach develop the l/d variation to determine both the number of the Andreev features and their amplitudes in the dI/dV spectrum. We show, in the spectrum of a diffusive SNS junction (l/d→1), a suppression of the Andreev excess current and a dramatic change in the current voltage I(V)-curve slope at low bias, with only the main harmonic at eV=2Δ bias voltage remaining well-distinguished in the dI/dV-spectrum. Additionally, we attempt to make a first-ever comparison between experimental data for the high-transparency SNS junctions (more than 85%) and theoretical predictions. As a result, we calculate the temperature dependences of amplitudes and areas of Andreev features within the extended KGN approach, which qualitatively agree with our experimental data obtained using a “break-junction” technique.
Effect of the streamwise pulsed arc discharge array on shock wave/boundary layer interaction control
Authors: Tang Mengxiao , Wu Yun , Guo Shanguang , Sun Zhengzhong , Luo Zhenbing
Published: July 2020

The streamwise pulsed arc discharge array (S-PADA), in which five actuators are connected in series with adjustable frequency, is employed to control the shock wave/boundary layer interaction (SWBLI) at a 24° compression ramp in a M = 2.0 flow and under two Reynolds numbers based on boundary layer thickness (Re1 = 46 800 and Re2 = 11 700). High-speed schlieren imaging at 50 000 fps is used for flow visualization. The schlieren snapshots, as well as the statistics of the image sequence, namely, mean and root-mean-square, are examined to reveal the control outcome. The results show that the separated wave foot gradually presents bifurcation and partial disappearance under Re1 with the increasing pulse number of the S-PADA, indicating the decline in the shock intensity. The increase in frequency does affect the control outcome remarkably because shock weakening effect can be achieved under Re1 through 10 kHz and 20 kHz actuations, while no obvious change can be observed by the 5 kHz actuation. The experiments under Re2, where little control effect is exerted by the same methods, are also discussed. It is believed that the separated wave under a lower Reynolds number of Re2 presents the poorly developed turbulent boundary layer; hence, the effective SWBLI control is difficult to be ensured.
Kinetic equation for particle transport in turbulent flows
Authors: Zhong De-Yu , Wang Guang-Qian , Zhang Ming-Xi , Li Tie-Jian
Published: July 2020

With a new approach based on the ensemble average over particle state transition paths in phase space, a kinetic equation for particles transported in turbulent flows is derived. The probability density function (PDF) for particles is defined as an ensemble average of a special fine-grained PDF, referred to as the local path density operator. The kinetic equation is derived from a Taylor series expansion of the PDF in terms of the cumulants with respect to particle paths in phase space and leads to a closed expression for its diffusion terms. It shows that the random forcing of eddy fluctuations, non-stationarity of turbulence, and inertia of particles are explicitly presented in the diffusion coefficient, which could help us to understand how particles are diffused by these underlying mechanisms. The kinetic equation is applicable to non-Markovian, non-Gaussian, and non-stationary stochastic processes, while for Markovian processes, it recovers the classical Fokker–Planck equation. The macroscopic equations for particle phase are derived based on the kinetic equation and compared with the direct numerical simulation of particles transported in turbulent flows.
Fast low-noise transimpedance amplifier for scanning tunneling microscopy and beyond
Authors: Štubian Martin , Bobek Juraj , Setvin Martin , Diebold Ulrike , Schmid Michael
Published: July 2020

A transimpedance amplifier has been designed for scanning tunneling microscopy (STM). The amplifier features low noise (limited by the Johnson noise of the 1 GΩ feedback resistor at low input current and low frequencies), sufficient bandwidth for most STM applications (50 kHz at 35 pF input capacitance), a large dynamic range (0.1 pA–50 nA without range switching), and a low input voltage offset. The amplifier is also suited for placing its first stage into the cryostat of a low-temperature STM, minimizing the input capacitance and reducing the Johnson noise of the feedback resistor. The amplifier may also find applications for specimen current imaging and electron-beam-induced current measurements in scanning electron microscopy and as a photodiode amplifier with a large dynamic range. This paper also discusses the sources of noise including the often neglected effect of non-balanced input impedance of operational amplifiers and describes how to accurately measure and adjust the frequency response of low-current transimpedance amplifiers.
On the elastic anisotropy of the entropy-stabilized oxide (Mg, Co, Ni, Cu, Zn)O compound
Authors: Pitike Krishna Chaitanya , Marquez-Rossy Andres E. , Flores-Betancourt Alexis , Chen De Xin , Santosh KC , Cooper Valentino R. , Lara-Curzio Edgar
Published: July 2020

In this paper, we study the elastic properties of the entropy-stabilized oxide (Mg, Co, Ni, Cu, Zn)O using experimental and first principles techniques. Our measurements of the indentation modulus on grains with a wide range of crystallographic orientations of the entropy-stabilized oxide revealed a high degree of elastic isotropy at ambient conditions. First principles calculations predict mild elastic anisotropy for the paramagnetic structure, which decreases when the system is considered to be non-magnetic. When the antiferromagnetic state of CoO, CuO, and NiO is accounted for in the calculations, a slight increase in elastic anisotropy is observed, suggesting a coupling between magnetic ordering and the orientation dependent elastic properties. Furthermore, an examination of the local structure reveals that the isotropy is favored through local ionic distortions of Cu and Zn—due to their tendencies to form tenorite and wurtzite phases. The relationships between the elastic properties of the multicomponent oxide and those of its constituent binary oxides are reviewed. These insights open up new avenues for controlling isotropy for technological applications through tuning composition and structure in the entropy-stabilized oxide or the high-entropy compounds in general.
Numerical simulation and modeling of the hydrodynamic forces and torque acting on individual oblate spheroids
Authors: Ouchene R.
Published: July 2020

Computation of a three-dimensional uniform, steady Newtonian flow past oblate spheroidal particles is undertaken. The main objective of the present study is to compute the hydrodynamic forces on oblate spheroidal particles as a function of the particle orientation, for different particle aspect ratios and a large range of particle Reynolds number. The results of the simulations are used to provide a new complete set of correlations for drag, lift, and torque coefficients. These correlations are derived for an aspect ratio ranging from 0.2 to 1, for particle Reynolds number up to 100, and for all orientations. In addition, it is found that the Stokesian evolution of the drag and lift coefficients as a function of the incidence remains still valid at moderate particle Reynolds number; that is, drag coefficient evolves as sine squared and lift coefficient evolves as (sin ϕ cos ϕ).
An improved theory of the response of DIII-D H-mode discharges to static resonant magnetic perturbations and its implications for the suppression of edge localized modes
Authors: Fitzpatrick R. , Nelson A. O.
Published: July 2020

The plasma response to an externally generated, static, n = 2, resonant magnetic perturbation (RMP) in the pedestal region of DIII-D H-mode discharge #158115 is investigated using a toroidal generalization of the asymptotic matching model presented by Fitzpatrick [Phys. Plasmas 27, 042506 (2020)]. Just as in a recent paper [Q. M. Hu et al., Phys. Plasmas 26, 120702 (2019)], it is hypothesized that the density pump-out phenomenon is due to locked magnetic island chains induced at the bottom of the pedestal, whereas the suppression of edge localized modes is associated with a locked magnetic island chain induced at the top of the pedestal. Neutral penetration inside the last closed magnetic flux-surface is found to have a significant influence on locked magnetic island chain formation at the bottom of the pedestal. It is found that locked island formation at the top of the pedestal is only possible when q95 lies in certain narrow windows. Finally, it is inferred that, in order to successfully induce a locked island chain at the top of the pedestal, an external RMP field-coil system must generate a magnetic field that is simultaneously strongly amplified by the plasma (via the ideal kink response) and has a large resonant component at a rational surface that lies close to the top of the pedestal.
Shock-tube measurements of coupled vibration–dissociation time-histories and rate parameters in oxygen and argon mixtures from 5000 K to 10 000 K
Authors: Streicher Jesse W. , Krish Ajay , Hanson Ronald K. , Hanquist Kyle M. , Chaudhry Ross S. , Boyd Iain D.
Published: July 2020

Shock-tube experiments were conducted behind reflected shocks using ultraviolet (UV) laser absorption to measure coupled vibration–dissociation (CVDV) time-histories and rate parameters in dilute mixtures of oxygen (O2) and argon (Ar). Experiments probed 2% and 5% O2 in Ar mixtures for initial post-reflected-shock conditions from 5000 K to 10 000 K and 0.04 atm to 0.45 atm. A tunable, pulsed UV laser absorption diagnostic measured absorbance time-histories from the fourth, fifth, and sixth vibrational levels of the electronic ground state of O2, and experiments were repeated—with closely matched temperature and pressure conditions—to probe absorbance time-histories corresponding to each vibrational level. The absorbance ratio from two vibrational levels, interpreted via an experimentally validated spectroscopic model, determined vibrational temperature time-histories. In contrast, the absorbance involving a single vibrational level determined vibrational-state-specific number density time-histories. These temperature and state-specific number density time-histories agree reasonably well with state-to-state modeling at low temperatures but deviate significantly at high temperatures. Further analysis of the vibrational temperature and number density time-histories isolated coupling parameters from the Marrone and Treanor CVDV model, including vibrational relaxation time (τ), average vibrational energy loss (ε), vibrational coupling factor (Z), and dissociation rate constant (kd). The results for τ and kd are consistent with previous results, exhibit low scatter, and—in the case of vibrational relaxation time—extend measurements to higher temperatures than previous experiments. The results for ε and Z overlap some common models, exhibit relatively low scatter, and provide novel experimental data.
Ionic conductivity and relaxation dynamics in plastic crystals with nearly globular molecules
Authors: Reuter D. , Seitz K. , Lunkenheimer P. , Loidl A.
Published: July 2020

We have performed a dielectric investigation of the ionic charge transport and the relaxation dynamics in plastic crystalline 1-cyano-adamantane (CNA) and in two mixtures of CNA with the related plastic crystals adamantane or 2-adamantanon. Ionic charge carriers were provided by adding 1% of Li salt. The molecules of these compounds have nearly globular shape and, thus, the so-called revolving-door mechanism assumed to promote ionic charge transport via molecular reorientations in other PC electrolytes should not be active here. Indeed, a comparison of the dc resistivity and the reorientational α-relaxation times in the investigated PCs reveals complete decoupling of both dynamics. Similar to other PCs, we find a significant mixing-induced enhancement of the ionic conductivity. Finally, these solid-state electrolytes reveal a second relaxation process, slower than the α-relaxation, which is related to ionic hopping. Due to the mentioned decoupling, it can be unequivocally detected and is not superimposed by the reorientational contributions as found for most other ionic conductors.
Passive control of coaxial jet with supersonic primary jet and sonic secondary jet
Authors: Perumal Arun Kumar , Singh Himanshu , Rathakrishnan Ethirajan
Published: July 2020

The mixing enhancement of a coaxial jet with a Mach 1.4 primary jet and sonic secondary jet, at different convective Mach numbers, is presented in this study. Rectangular tabs of aspect ratios (AR = h/w, where h and w are the tab height and width, respectively) 2.0 and 0.75 were employed to manipulate the primary and secondary jets, respectively. The primary jet (C0) and coaxial jet without control or manipulation (C1) are studied in order to decouple the effects of rectangular tabs on jet mixing. Four different tab configurations were studied, viz., tabs placed in the primary jet (C2), tabs placed in the secondary jet (C3), and tabs placed in both primary and secondary jets with the relative orientation between them of 0° (C4) and 90° (C5), to document the effect of tabs on mixing. The supersonic core length Lc* of the manipulated jet was used as a measure to quantify the mixing performance of the manipulated jet. The secondary flow reduces the growth rate of the primary shear layer and elongates the supersonic core length. This study reveals that the manipulated jet emulates the characteristic of a non-circular jet. Primary tabs are highly effective in reducing the supersonic core length of the coaxial jet than secondary tabs, and hence, the jet mixing increases. Two different flow categories of the manipulated jet have been identified. The physical reason behind the observed jet mixing and flow categories have been presented based on arguments related to changes in the flow field and shock structure.
On sustaining turbulence production in interacting supersonic streamwise vortices
Authors: Viganò D. , Maddalena L.
Published: July 2020

Interacting supersonic streamwise vortices have been investigated as a means to enhance mixing at supersonic velocities. However, the turbulence dynamics associated with this class of flow has been left largely unexplored despite turbulence playing a major role in the achievement of molecular mixing. For this reason, the process of turbulent kinetic energy production in interacting supersonic streamwise vortices is investigated in this work. Specifically, the link between the mean flow motion and turbulence, represented by the production term of the turbulent transport equation, is analyzed. An approach is proposed in which the mean flow strain rates can be cast such that their intensity and morphology properly couple with the requirements imposed by the Reynolds stresses that, in the framework of this work, are shown to be intimately linked with the resulting plume morphology. The analysis is leveraged for the design of a mode of vortex interaction targeted to maintain a positive production of turbulent kinetic energy in the downstream evolution. The resulting configuration was experimentally investigated in a Mach 2.5 flow by stereoscopic particle image velocimetry. The results from these experiments show that the turbulence production remained positive and sustained turbulence levels, a unique result in the available literature. The role of turbulence anisotropy and the principal direction of negative planar strain rates are highlighted in detail in this work.
Wave-driven non-classical electron transport in a low temperature magnetically expanding plasma
Authors: Hepner Shadrach , Wachs Benjamin , Jorns Benjamin
Published: July 2020

The presence of instabilities in a low density, low temperature plasma expanding through an axially symmetric magnetic nozzle is investigated in the context of non-classical electron cross field transport. Electrostatic probes are used to characterize the background plasma properties and instabilities. The measurements show a primarily azimuthally propagating mode with a broad, incoherent power spectrum that appears linear at low frequencies. It is demonstrated that the observed dispersion is consistent with the lower hybrid drift instability. The energy and linear growth rate of this wave are related through quasilinear theory to an effective electron collision frequency that is shown to be dominant over classical collisions.
Dynamic sheath formation and sub-THz radiation from laser–metal interactions
Authors: Davidson A. , Petrov G. M. , Rock B. , Grugan P. , Gordon D. , Hafizi B. , Ting A. , Peñano J.
Published: July 2020

The generation of low-frequency radiation from a short pulse (∼100 fs) laser with mJ energy incident on a metal surface is investigated. The electrons within the metal surface absorb energy from the laser pulse, increasing in temperature to a few electron volts and resulting in some at the high-energy tail of the distribution to overcome the work function barrier. Emission of these electrons from the surface contributes to a surface current which sources secondary radiation emission. The Richardson–Dushman emission picture breaks down due to Coulombic effects and a modified emission model is presented. Previous precedence exists for modified thermionic emission models for laser–metal interactions of a similar nature, such as the one presented by Riffe et al. [J. Opt. Soc. Am. B 10, 1424–1435 (1993)] upon which we elaborate. Surface currents generated by such a mechanism are modeled with a particle-in-cell (PIC) simulation together with a Monte Carlo treatment of electron–neutral collisions with air molecules. The modified emission model, together with the PIC model, provides a numerical basis from which the radiated spectra are estimated due to the time-varying currents emitted from the surface of the metal. Experiments and numerical simulations for air pressure between 0.1 and 1 atm show qualitative agreement as to the pressure dependence of the measured signal energy from the secondary radiation, with Emeasured∝Pair−α for some α near but less than 1. Quantitative agreement between experiments and simulations is improved by including the effect of an additional contribution to secondary emission energy arising from inverse-bremsstrahlung collisions within a nm-scale vapor layer.
On the use of leading-edge serrations for noise control in a tandem airfoil configuration
Authors: Vemuri SH. S. , Liu X. , Zang B. , Azarpeyvand M.
Published: July 2020

Passive noise control for a tandem NACA 65-710 airfoil configuration is experimentally investigated by applying leading-edge serrations on the rear airfoil. With a sliding side-plate mechanism that allows the rear airfoil to move in the vertical direction relative to the front airfoil, the position of maximum turbulence interaction noise is first identified from the far-field noise measurements. Subsequently, detailed static surface pressure distribution and unsteady surface pressure fluctuations are acquired to shed more light on the physical phenomenon and underlying noise-reduction mechanism of the leading-edge serrations. The far-field noise measurements confirm that a notable turbulence interaction noise reduction can be achieved from 600 Hz < f < 3000 Hz, agreeing well with the previous literature on the effectiveness of the leading-edge serrations. The near-field hydrodynamic analyses obtained using remote-sensing techniques of the fluctuating pressure fields over the airfoil show that a significant reduction in the surface pressure fluctuation levels up to 20 dB/Hz can be observed at the serrated-tip plane of the rear serrated airfoil close to the leading-edge regions, over the range of frequencies investigated. Although reduction can also be observed on the serrated-root plane, the magnitude is much less significant. The present results suggest that the modification of the unsteady loading on the rear airfoil by the leading-edge serrations plays a crucial role in the reduction of turbulence interaction noise in the tandem airfoil configuration, which may find practical application for noise reduction in aerodynamic systems involving rows of airfoils, such as contra-rotating open rotors and outlet guide vanes.
Stealthy movements and concealed swarms of swimming micro-robots
Authors: Mirzakhanloo Mehdi , Alam Mohammad-Reza
Published: July 2020

Here, we show that micro-swimmers can form a concealed swarm through synergistic cooperation in suppressing one another’s disturbing flows. We then demonstrate how such a concealed swarm can actively gather around a favorite spot, point toward a target, or track a desired trajectory in space, while minimally disturbing the ambient fluid. Our findings provide a clear road map to control and lead flocks of swimming micro-robots in stealth vs fast modes, tuned through their active collaboration in minimally disturbing the host medium.
Transition metals as optically active dopants in glass-ceramics
Authors: Cormier L. , Zhou S.
Published: July 2020

Over the past few decades, glass-ceramics doped with transition metals have become promising materials for the development of active and passive optical functional devices, including a wide variety of commercial applications due to their unique properties. In this Perspective paper, the intrinsic advantages of these composite materials are outlined, and we provide an overview of recent and on-going progress and state-of-the-art knowledge of the main applications: broadband amplifiers, tunable lasers, long persistent phosphors, noninvasive optical temperature sensors, saturable absorbers, high IR emitters, and thermal shock-resistant color filters. Finally, today's challenges and future prospects are exposed to provide guidelines for future research.
Laser spectroscopy: A new way to study pions
Authors: Miller Johanna L.
Published: July 2020

By creating exotic atoms containing an ever-broadening range of particles, researchers can extend the tools of atomic physics to new realms.
The physics of river prediction
Authors: Fleming Sean W. , Gupta Hoshin V.
Published: July 2020

Resource managers use forecasts to ensure future access to abundant water and provide safety from river-related hazards.
Dust devils on Mars
Authors: Lorenz Ralph D.
Published: July 2020

Whirlwinds, familiar on Earth, can be informative probes of the Martian surface environment.
Screen identifies DYRK1B network as mediator of transcription repression on damaged chromatin
Authors: Dong Chao , West Kirk L. , Tan Xin Yi , Li Junshi , Ishibashi Toyotaka , Yu Cheng-han , Sy Shirley M. H. , Leung Justin W. C. , Huen Michael S. Y.
Published: July 2020

Significance

Cells avoid clashes between DNA repair machineries and the transcription apparatus by temporary halting gene expression in the vicinity of DNA double-strand breaks (DSBs), an emerging DNA damage response (DDR) that underlies genome integrity protection. In this study, we screened for novel activities that may be important in this DDR and have identified the DYRK1B kinase as a component of the mammalian DDR that specializes in fine-tuning DSB repair on actively transcribed chromatin. Moreover, global analysis of DYRK1B substrates has led to the identification of the histone methyltransferase EHMT2 as a DYRK1B target and effector. Our findings uncover the DYRK1B network as a DDR subpathway that preserves the integrity of active chromatin.
Time-dependent plasticity in silicon microbeams mediated by dislocation nucleation
Authors: Elhebeary Mohamed , Harzer Tristan , Dehm Gerhard , A. Saif M. Taher
Published: July 2020

Significance

Although silicon is the most used material in electronics industry, its mechanical behavior is still not fully understood. Silicon is considered to be a brittle material, but it becomes ductile at the brittle-to-ductile transition temperature of 540 °C. We reveal that silicon micromechanical beams exhibit time-dependent ductility at low temperatures under bending stresses. Generation of dislocations from the beam surface and their motion into the bulk mediate the plasticity. The study offers fundamental insights into the deformation mechanism of silicon. Most sensors and actuators, such as accelerometers, employ microbeams as springs. The results of this study are relevant to the design and reliability estimation of such silicon devices operating under high temperatures and stresses.
Male reproductive aging arises via multifaceted mating-dependent sperm and seminal proteome declines, but is postponable in
Drosophila
Authors: Sepil Irem , Hopkins Ben R. , Dean Rebecca , Bath Eleanor , Friedman Solomon , Swanson Ben , Ostridge Harrison J. , Harper Lucy , Buehner Norene A. , Wolfner Mariana F. , Konietzny Rebecca , Thézénas Marie-Laëtitia , Sandham Elizabeth , Charles Philip D. , Fischer Roman , Steinhauer Josefa , Kessler Benedikt M. , Wigby Stuart
Published: July 2020

Significance

Reduced fertility with advancing age is well known in females but understudied in males. Most previous work on male reproductive aging has focused on age-related effects on sperm. However, nonsperm seminal fluid is also vital for fertility but might age differently. Using fruit flies, we find that seminal fluid and sperm are both qualitatively and quantitatively affected by age with each making distinct contributions to declining reproductive performance in older males. However, the relative impacts on sperm and seminal fluid often differ, leading to mismatches between ejaculate components. Despite these differences, experimental extension of male lifespan can improve overall ejaculate performance in later life, suggesting that such interventions can delay both male reproductive aging and death.
Vowel system or vowel systems?
Authors: Wong Gonzales Wilkinson Daniel , Starr Rebecca Lurie
Published: July 2020

The Manila variety of Philippine Hybrid Hokkien (PHH-M) orLánnang-uèis a contact language used by the metropolitan Manila Chinese Filipinos; it is primarily comprised of Hokkien, Tagalog/Filipino, and English elements. Approaching PHH-M as a mixed language, we investigate linguistically and socially conditioned variation in the monophthongs of PHH-M, focusing on the extent to which the vowel systems of the three source languages have converged. This analysis draws on data gathered from 34 native speakers; Pillai scores are calculated to assess the degree of merger. Contrary to certain predictions of prior work on mixed languages, PHH-M is found to have a unified, eight-vowel inventory distinct from any of its sources. Older women use more stable vowels across source languages, suggesting that they have led in the development of PHH-M as a mixed code; however, signs of change among younger women suggest either the endangerment of the code or its evolution in response to the community’s shifting identity. We contextualize our conclusions in relation to the sociohistory and language ecology of metropolitan Manila’s Chinese Filipino community.
Changes in the functions of already in Singapore English
Authors: Ziegeler Debra
Published: July 2020

The use of the adverb already in Colloquial Singapore English has long been known as one of the most readily recognizable features defining the contact dialect, marking aspectual nuances such as anterior, completive, inchoative and inceptive functions, as noted by Bao (2005, 2015). Recent observations note that the uses of already as an inchoative marker (distinguishing the adverb as an iamitive) are more frequently found than completive uses across a small, synchronic sample of speakers (Teo 2019). It is perhaps less often recognized, though, that the aspectual use of already co-exists with the variable marking for past tense in Singlish (Ho & Platt 1993), and that both the aspectual adverb and the past tense may be seen to co-occur in the same construction. The frequency of already in its various functions is examined across two corpora, and the relative frequency of completive vs. non-completive functions is quantified diachronically. It is hypothesized that, rather than grammaticalizing onwards to become a past tense marker, as is predictable for some Portuguese creole iamitives (ya ‘already’) (Clements 2006), already is becoming increasingly restricted in its functional range in today’s Singlish, and that its perfect and completive functions may be at a stage of selective renovation by the use of the past tense in Standard Singapore English.
Suppletion in Tagdal
Authors: Benítez-Torres Carlos M.
Published: July 2020

Northern Songhay languages are known for combining Songhay and Tuareg-Berber features.Nicolaï (1979)divided these languages into nomadic and sedentary sub-branches, something whichBenítez-Torres and Grant (2017)confirmed, bears out very well from a grammatical standpoint. This paper explores some of the interactions between Songhay and Berber vocabulary by looking at suppletion in Tagdal, a nomadic Northern Songhay language. In Tagdal, suppletion occurs when a verb root of Songhay origin is replaced by one of Berber origin whenever a Berber derivational prefix is present. It will be demonstrated that when Tagdal was in its formative period, the prosodic features that came along with the Songhay and Berber portions of the language made it either easier or necessary to keep the two apart. The paper ends with a brief discussion of how Songhay and Berber vocabulary may have interacted during the period when Tagdal and other Northern Songhay languages were still being formed.
High-spin states of 218Th
Authors: O’Donnell D , Page R D , Grahn T , Ali F A , Auranen K , Capponi L , Carroll R J , Chishti M M R , Drummond M C , Greenlees P T , Henderson J , Herzan A , Jakobsson U , Joss D T , Julin R , Juutinen S , Konki J , Labiche M , Leino M , Mason P J R , McPeake C G , Pakarinen J , Papadakis P , Partanen J , Peura P , Rahkila P , Revill J , Ruotsalainen P , Sandzelius M , Sarén J , Sayği B , Scholey C , Simpson J , Smith J F , Smolen M , Sorri J , Stolze S , Sullivan C M , Thornthwaite A , Uusitalo J , Kumar A , Srivastava P C
Published: July 2020

High-spin states in the N = 128 nucleus 218Th have been investigated following fusion–evaporation reactions, using the recoil-decay tagging technique. Due to the short-lived nature of the ground state of 218Th prompt γ rays have been correlated with the α decay of the daughter nucleus 214Ra. The level scheme representing the decay of excited states has been extended to (16+) with the observation of six previously unreported transitions. The observations are compared with the results of shell model calculations and within the context of the systematics of neighbouring nuclei.
Robust treatment planning with 4D intensity modulated carbon ion therapy for multiple targets in stage IV non-small cell lung cancer
Authors: Wolf M , Anderle K , Durante M , Graeff C
Published: July 2020

Intensity modulated particle therapy (IMPT) with carbon ions can generate highly conformal treatment plans; however, IMPT is limited in robustness against range and positioning uncertainty. This is particularly true for moving targets, even though all motion states of a 4DCT are considered in 4D-IMPT. Here, we expand 4D-IMPT to include robust non-linear RBE-weighted optimization to explore its potential in improving plan robustness and sparing critical organs. In this study, robust 4D-optimization—based on worst-case optimization on 9 scenarios—was compared to conventional 4D-optimization with PTV margins using 4D dose calculation and robustness analysis for 21 uncertainty scenarios. Slice-by-slice rescanning was used for motion mitigation. Both 4D-optimization strategies were tested on a cohort of 8 multi-lesion lung cancer patients with the goal of prioritizing OAR sparing in a hypofractionated treatment plan. Planning objectives were to keep the OAR volume doses below corresponding limits while simultaneously achieve CTV coverage with D95% ≥ 95 %. For the conventional plans, average D95% was at 98.7% which fulfilled the target objective in 83.2% of scenarios. For the robust plans, average D95% was reduced to 97.6% which still fulfilled the target objective in 80.7% of cases, but led to significantly improved overall OAR sparing: Volume doses were below the limits in 96.2% of cases for the conventional and 99.5% for the robust plans. When considering the particularly critical smaller airways only, fulfillment rates could be increased from 76.2% to 96% for the robust plans. This study has shown that plan robustness of 4D-IMPT could be improved by using robust 4D-optimization, offering greater control over uncertainties in the actual delivered dose. In some cases, this required sacrificing target coverage for the benefit of better OAR sparing.
Double-propagation mode in short-gap spark discharges driven by HV pulses with sub-ns rise time
Authors: Höft H , Becker M M , Kolb J F , Huiskamp T
Published: July 2020

The object of this study is the investigation of spark discharges ignited by unipolar positive rectangular high voltage (HV) pulses with 200 ps rise time and (15 ± 2) kV amplitude with 3 ns duration full width at half maximum in synthetic air in a 1.2 mm pin-to-pin gap (tungsten electrodes) at atmospheric pressure. The discharge development was recorded by synchronised iCCD and streak camera measurements in single-shot operation, revealing a two-stage propagation mode. The discharge started with a fast initial breakdown across the entire gap (∼10 mm ns−1) during the HV slope, followed by a much slower (∼0.1 mm ns−1) propagation originating from both electrodes towards the gap centre. The combination of high-resolution diagnostics with numerical modelling indicated that the initial breakdown phase is caused by the rapid increase of electric field strength during the steep HV slope, which leads to the simultaneous fast propagation of a positive and a negative streamer.
Routes to control Cooper minimum in high order harmonics generated in argon gas
Authors: Boltaev G S , Ganeev R A , Abbasi N A , Iqbal M , Kim V V , Al-Harmi H , Tong X M , Alnaser A S
Published: July 2020

We present a systematic study on the control of Cooper minimum (CM) in the high-order harmonics spectra generated during the interaction of Ar gas with ultrashort near-infrared laser pulses. Tailoring the width and depth of CM in argon is demonstrated by changing the gas jet position with respect to the focal plane of focusing lens and by defocusing-assisted phase-matching. We further analyze the influence of single- and two-color laser pump schemes on the appearance of CM. The application of two orthogonally-polarized fields of fundamental radiation and its second harmonic, which is also used to generate controllable yields of odd and even harmonics, led to diminishing the CM in the harmonic spectra. Our experimental findings are supported by theoretical calculations that solve the time-dependent Schrödinger equation in the microscopic domain, and take into account the phase matching in the macroscopic domain.
Controlling the helicity of magnetic skyrmions by electrical field in frustrated magnets
Authors: Yao Xiaoyan , Chen Jun , Dong Shuai
Published: July 2020

The skyrmions generated by frustration in centrosymmetric structures host extra internal degrees of freedom—vorticity and helicity, resulting in distinctive properties and potential functionality, which are not shared by the skyrmions stemming from the Dzyaloshinskii–Moriya interaction in noncentrosymmetric structures. The present work indicates that the magnetism-driven electric polarization carried by skyrmions provides a direct handle for tuning helicity. Especially for the in-plane magnetized skyrmions, the helicity can be continuously rotated and exactly picked by applying an external electric field for both skyrmions and antiskyrmions
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The in-plane uniaxial anisotropy is beneficial to this manipulation.
Vega-Les Information System. Actual Features and Future Evolution
Authors: Balashov I , Bartalev S , Bartalev S , Burtsev M , Vorushilov I , Egorov V , Kashnitskii A , Khovratovich T , Khvostikov S , Kobets D , Loupian E , Saigin I , Senko K , Stytsenko F , Sychugov I , Zharko V
Published: July 2020

The paper describes the Vega-Les (“Les” is the Russian word meaning “forest”) information system developed in the Space Research Institute of the Russian Academy of Sciences (IKI) for complex monitoring of the Russian forests with satellite data. The Vega-Les information system provides online access to continuously updated long term Earth remote sensing data and derived products archives and automated data processing, analysis and synthesis online tools for wide range of remote users for forest resources monitoring and research. The paper gives information about system’s main features, available satellite data and provides examples of data analysis and processing tools.
About the methodology of geo-risk management in forestry
Authors: Istomin E , Petrov Y , Stepanov S , Sidorenko A , Martyn I
Published: July 2020

The article examines the components of risk management, considers industry risks in forestry management. A risk management methodology in forestry is proposed based on a controlled parameter. The preliminary data processing for working with the model is considered.
The use of information and infocommunication technologies in the management of urban forests of St. Petersburg using geographic information systems
Authors: Kolbina O , Yagotinceva N , Bogdanov P. , Istomin E. , Vagizov M
Published: July 2020

The article considers the possibility of using infocommunication technologies in the management of urban forests. There are schemes and models of integration the Internet of things into geoinformation systems for making managerial decisions that contribute to the care of green spaces in the city of St. Petersburg.
Method for solving problems of the theory restrictions of infocommunication systems using linear equations with many unknowns
Authors: Malikova D M , Slashchev E S , Istomin E P , Vagizov M R , Kolbina O E
Published: July 2020

The article presents a method for solving problems of theory of constraint in the form of linear equations with many unknowns encountered in practice when managing the life cycle of engineering products. The development of any type of info-communication systems may include mathematical modeling of current processes based on a system of linear equations. The use of the method is meant for automating the process of substantiating the decisions taken at the stage of preparation for production and managing the product life cycle when managing dimensional, temporary and economic relations. The example of the first problem describes the key aspects of pricing and remuneration taking into account the productivity of workers. The second problem is to determine the economically achievable tolerance of the closing link of a dimension chain. The third problem describes the aspects of the enterprise load, taking into account mandatory contributions. These problems allow us to find a rational solution with a limited number of input data. The presented problems reveal a method for solving the problems of the theory of constraint and the prospects of using equations for practice in managing the life cycle and building automated systems.
Assessment of the influence of natural and climatic conditions on forest carting out
Authors: Mokhirev A , Bragina N , Medvedev S
Published: July 2020

There were many factors that influence the volume of forest carting out. They were divided into managed and unmanaged. The human impact on unmanaged factors was minimized. These included the natural and climatic conditions under which the wood carting out took place. However, these factors were among the most significant, especially in Siberia, in sharply continental conditions. The purpose of this study was to assess the influence of natural and climatic factors on forest carting out using the mathematical tool. For research data were collected on the volume of daily carting out of wood from forest areas for several years in the winter time. For the same dates, information was collected on climatic conditions: air humidity; wind speed; type of precipitation; precipitation duration; maximum air temperature; minimum air temperature; amount of precipitation; visibility range; snow depth. Multivariate analysis was performed using the Microsoft Office Excel software product, as well as controlling calculations in the Statistica 10.0 statistical product. As a result, the linear multiple regression equation was obtained.
Alternative energy in vegetable and crushed wood raw materials drying processes
Authors: Mukhametzyanov Sh R , Safin R R , Ilalova G F , Mukhtarova A R , Shageeva A I
Published: July 2020

The article describes an self-contained complex energy-saving plant for remote areas, that provides heat and electricity for the needs of a condenser kiln by thermochemical gasification of logging, woodworking, and agricultural waste. A special feature of the proposed plant is the condenser kiln which allows minimizing the cost of heat energy by using a compression heat pump and implementing pulse drying modes consisting of alternate stages of heating and drying. A pulse process helps avoid the use of water vapor while maintaining the quality characteristics of the materials to be dried. It was found that the use of torrefied crushed raw materials as an alternative energy source can increase the productivity of the entire self-contained drying plant.