bluuebunny/crossref_metadata_2025 huggingface dataset:
Broadband body‐worn antenna using a top‐loaded pyramidal radiator
Authors: Jackson Brad R. , Merkley Eric
Published: January 2020

A wide‐bandw
idth low‐profile quasi‐omnidirectional antenna is presented and experimentally demonstrated when integrated with a helmet for emergency services or military applications. The antenna consists of a pyramid‐shaped radiator that is top‐loaded with an etched copper‐clad microwave laminate with two shorting strips used to improve the input impedance matching, particularly for lower frequencies. The design and operation of the antenna are first introduced using a flat ground plane, and then experimental results are reported when it is installed on a helmet where the outer surface of the helmet is used as the ground plane. The results show a very wide impedance bandwidth from 890 MHz to 13.7 GHz (VSWR 3) and predominately monopole‐like radiation patterns up to 11 GHz. The antenna has a height of /16 at the lowest operating frequency of 890 MHz (21 mm). Simulation results with a human body model demonstrate the significantly improved omnidirectionality of the proposed helmet antenna compared to more conventional body‐worn antennas used in some applications.
Bias thermal stability improvement of MEMS gyroscope with quadrature motion correction and temperature self‐sensing compensation
Authors: Cui Jian , Zhao Qiancheng
Published: January 2020

Bias thermal stability of microelectromechanical system (MEMS) gyroscope is a significant performance parameter for industrial and tactical applications. The quadrature coupling motion and demodulation phase error are two main sources of bias drift. This work presents a MEMS tuning fork gyroscope with dedicated electrostatic correction combs finger structure that can be implemented to suppress the quadrature motion. By utilising a closed‐loop control for the coupling stiffness, the temperature variation of quadrature motion achieves >260 times of magnitude reduction, resulting in the thermal bias drift decreased from 0.98 to 0.18°/s with 5.4 times improvement over the temperature from −40 to 60°C. The results indicate that the variation of the quadrature motion is the dominant factor that determines the temperature bias drift of the custom‐designed gyroscope. The compensated bias stability (1σ) is measured to be ∼8.6°/h by using temperature self‐sensing compensation technique over the whole temperature operating range, which demonstrates a considerably competitive result for the tactical‐grade MEMS gyroscope.
AC‐SJ VDMOS with ultra‐low resistance
Authors: Wang Yandong , Duan Baoxing , Zhang Chen , Wang Xiameng , Yang Yintang
Published: January 2020

An accumulation superjunction (AC‐SJ) vertical power metal–oxide–semiconductor field‐effect transistor (VDMOS) is proposed and its mechanism is investigated. Different from the conventional VDMOS, a number of carriers are accumulated and modulate the conductivity of the drift region when the AC‐SJ VDMOS works in the on‐state. The causes of carrier AC and the factors affecting the amount of carrier are analysed. The influences of these factors on the output characteristics are studied by simulation. Simulation results show that the on specific resistance (Ron,sp) of the AC‐SJ VDMOS decreases from 6.64 mΩ cm2 of the conventional VMOS to 1.53 mΩ cm2 with the same drift region length of 15 μm. The AC‐SJ VDMOS obtains very low Ron,sp by accumulating electrons while maintains high breakdown voltage due to SJ theory, thereby breaking the SJ limit in silicon.
Synthesis and photocatalytic property of Cu2CoSnS4 nanocrystals with stannite and wurtzite structure
Authors: Guan Hao , Ma Xiao , Zhao Jia
Published: January 2020

Stannite and wurtzite Cu2CoSnS4 (CCTS) nanocrystals are successfully prepared via a solvothermal approach. X‐ray diffraction and Raman spectroscopy reveal that pure CCTS phases with stannite and wurtzite structure are obtained. Scanning electron microscopy shows that CCTS nanocrystals with stannite structure are composed of nanosheets with the thickness of about 50 nm while CCTS nanocrystals with wurtzite structure exhibit large number of irregular nanoparticles. Furthermore, photoluminescence (PL) spectroscopy and UV–Vis spectroscopy are used to investigate optical and photocatalytic properties of CCTS nanocrystals. When CCTS nanocrystals with stannite and wurtzite structure are used as photocatalysts, the degradation of methylene blue can reach up to 72 and 53%, respectively, within 100 min under visible‐light irradiation, which are suitable for effective visible‐light photocatalysts.
Enhanced conductivity of anatase TiO2 nanowires by La and Co co‐doping
Authors: Li Shanying , Wang Zhenxin , Yang Yilong , Li Jie , Jin Chi
Published: January 2020

In this work, the conductivity of anatase titanium dioxide (TiO2) nanowires was enhanced by lanthanum (La) and cobalt (Co) co‐doping method. The nanowires were synthesised via a facile solvothermal process. The diameter of as‐synthesised nanowires is about 300 nm and length more than 20 μm. The electrical properties were studied based on single nanowire field‐effect transistor; the anatase TiO2 nanowires exhibit n‐type conductivity with mobility of 2.18 cm2 V−1 S−1 and carrier concentration of 1.95 × 1018 cm−3. Doping of rare earth element La and transition element Co can not only reduce bandgap, but also reduce electron–hole recombination and improve carrier concentration. The distinct electrical properties of doped nanowires will open new opportunities for the application of anatase TiO2 semiconductor materials in nanoelectronics devices.
Tips and tricks in linear imaging polarimetry of extended sources with FORS2 at the VLT
Authors: González-Gaitán S. , Mourão A. M. , Patat F. , Anderson J. P. , Cikota A. , Wiersema K. , Higgins A. B. , Silva K.
Published: January 2020

Context. Polarimetry is a very powerful tool for uncovering various properties of astronomical objects that otherwise remain hidden in standard imaging or spectroscopic observations. While common observations only measure the intensity of light, polarimetric measurements allow us to distinguish and measure the two perpendicular components of the electric field associated with the incoming light. By using polarimetry it is possible to unveil asymmetries in supernova explosions, properties of intervening dust, characteristics of atmosphere of planets, among others. However, the reliable measurement of the low polarization signal from astronomical sources requires a good control of spurious instrumental polarization induced by the various components of the optical system and the detector.

Aims. We perform a detailed multi-wavelength calibration study of the FORS2 instrument at the VLT operating in imaging polarimetric mode to characterize the spatial instrumental polarization that may affect the study of extended sources.

Methods. We used imaging polarimetry of high signal-to-noise ratio blank field BVRI observations during the full moon, when the polarization is expected to be constant across the field of view and deviations originate from the instrument, and a crowded star cluster in broad-band RI and narrow-band Hα filters, where the individual polarization values of each star across the field can be measured.

Results. We find an instrumental polarization pattern that increases radially outwards from the optical axis of the instrument reaching up to 1.4% at the edges, depending on the filter. Our results are closely approximated by an elliptical paraboloid down to less than ∼0.05% accuracy, and ∼0.02% when using non-analytic fits. We present 2D maps to correct for this spurious instrumental polarization. We also give several tips and tricks for analyzing polarimetric measurements of extended sources.

Conclusions. FORS2 is a powerful instrument that allows the linear polarimetry of extended sources to be mapped. We present and discuss a methodology that can be used to measure the polarization of such sources, and to correct for the spatial polarization induced in the optical system. This methodology could be applied to polarimetric measurements using other dual-beam polarimeters.
Orientation of the crescent image of M 87*
Authors: Nalewajko Krzysztof , Sikora Marek , Różańska Agata
Published: January 2020

The first image of the black hole (BH) M 87* obtained by the Event Horizon Telescope (EHT) has the shape of a crescent extending from the E to WSW position angles, while the observed direction of the large-scale jet is WNW. Images based on numerical simulations of BH accretion flows suggest that on average the projected BH spin axis should be oriented SSW. We explore highly simplified toy models for geometric distribution and kinematics of emitting regions in the Kerr metric, perform ray tracing to calculate the corresponding images, and simulate their observation by the EHT to calculate the corresponding visibilities and closure phases. We strictly assume that (1) the BH spin vector is fixed to the jet axis, (2) the emitting regions are stationary and symmetric with respect to the BH spin, and that (3) the emissivities are isotropic in the local rest frames. Emission from the crescent sector between SSE and WSW can be readily explained in terms of an equatorial ring with either circular or plunging geodesic flows, regardless of the value of BH spin. In the case of plane-symmetric polar caps with plunging geodesic flows, the dominant image of the cap located behind the BH is sensitive to the angular momentum of the emitter. Within the constraints of our model, we have not found a viable explanation for the observed brightness of the ESE sector. Most likely, the ESE “hotspot” has been produced by a non-stationary localised perturbation in the inner accretion flow. Alternatively, it could result from locally anisotropic synchrotron emissivities. Multi-epoch and polarimetric results from the EHT will be essential to verify the theoretically expected alignment of the BH spin with the large-scale jet.
Effect of metallicity on the detectability of rotational periods in solar-like stars
Authors: Witzke V. , Reinhold T. , Shapiro A. I. , Krivova N. A. , Solanki S. K.
Published: January 2020

The accurate determination of stellar rotation periods is important for estimating stellar ages and for understanding stellar activity and evolution. While rotation periods can be determined for about thirty thousand stars in the Kepler field, there are over one hundred thousand stars, especially with low photometric variability and irregular pattern of variations, for which rotational periods are unknown. Here we investigate the effect of metallicity on the detectability of rotation periods. This is done by synthesising light curves of hypothetical stars that are identical to our Sun with the exception of the metallicity. These light curves are then used as an input to the period determination algorithms. We find that the success rate for recovering the rotation signal has a minimum close to the solar metallicity value. This can be explained by the compensation effect of facular and spot contributions. In addition, selecting solar-like stars with near-solar effective temperature and photometric variability, and with metallicity between M/H = −0.35 and M/H = 0.35 from the Kepler sample, we analyse the fraction of stars for which rotational periods have been detected as a function of metallicity. In agreement with our theoretical estimate we find a local minimum for the detection fraction close to the solar metallicity. We further report rotation periods of 87 solar-like Kepler stars for the first time.
French translation and validation of the Movement Imagery Questionnaire-third version (MIQ-3f)
Authors: Robin Nicolas , Coudevylle Guillaume R. , Guillot Aymeric , Toussaint Lucette
Published: January 2020

Objectives: Imagery ability is a variable influencing the effectiveness of imagery practice that can be estimated by means of questionnaires. Among them, the Movement Imagery Questionnaire-Revised, translated and validated in French, is widely used by French speakers. However, it does not allow for the distinction between the two visual imagery perspectives (internal vs. external). The Movement Imagery Questionnaire-3 has been recently proposed in the English literature to differentiate between the ease of performing internal visual, external visual and kinesthetic imagery. The aim of this study was to translate and validate a French version of this questionnaire (MIQ-3f). Method: We examined the validity of constructs, internal consistency, and test-retest inter-rate reliability of the visual and kinesthetic items of the MIQ-3f in 272 healthy participants (Mage = 20.26 years, SD = 1.73). Results: The internal consistency (composite reliability scores ≥ 0.88 for the three subscales) and test-retest reliability (intraclass correlation coefficients: 0.87 for visual internal imagery, 0.86 for visual external imagery, and 0.88 for kinesthetic imagery) of the MIQ-3f were satisfactory. The three-factor structure (with 4 items for each factor) was supported by confirmatory factor analysis. The MIQ-3f appears to be a valid and reliable instrument that can be used to assess imagery ability in French speakers.
Dye-based chromoendoscopy following polypectomy reduces incomplete polyp resection
Authors: O’Morain Neil R. , Syafiq Mohd I. , Shahin Ammar , Ryan Barbara , Crowther Stephen , McNamara Deirdre
Published: January 2020

Background and study aims The completeness of a polyp resection is an important determinant of quality in colonoscopy, and may reduce incidence of interval cancers. Incomplete resection rates (IRR) vary widely and range from 6.5 % to 22.7 %. Residual disease is more likely with larger polyps, for sessile serrated adenomas, and with more proximal lesions. Chromoendoscopy is increasingly employed in lesion detection. The aims of this study were to assess local IRR, and to determine whether chromoendoscopy could correctly identify residual disease post polypectomy.

Patients and methods This was a prospective study examining post polypectomy sites. Chromoendoscopy (0.13 % indigo carmine) was applied to resection bases to identify residual disease. Targeted base biopsies were taken from identified residual disease (positive group) or random base biopsies were taken when a clear base was visualised (negative group). Overall rates of incomplete resection were documented. Reported rates post chromoendoscopy and actual histological rates were documented and compared.

Results A total of 102 polyps were identified for inclusion, of which 15 % (n = 16) were excluded. Resection quality was evaluated in 86 polyps of 61 patients (female n = 33 54 %; mean Age 62.3 years). Polyps were mainly removed by cold snare (n = 71, 82.5 %). Most polyps (n = 58, 67 %) measured between 5 to 10 mm. Polyps were largely located in the right colon (n = 57, 66 %). Overall histological residual disease occurred in 17 /86 (19.6 %). Chromoendoscopy correctly identified residual disease in 13 of 17 bases (76.5 %). Only four of /86 (4.6 %) of polyp bases were missclassified post-chromoendoscopy (odds ratio 0.284 (95 % CI 0.0857–0.9409), P = 0.03).

Conclusion Indigo carmine chromoendoscopy improves early detection of residual disease post polypectomy, reducing incomplete resection rates.
Anti-B-Zell-Antikörpertherapie zur Remissionserhaltung bei Granulomatose mit Polyangiitis und mikroskopischer Polyangiitis
Authors: de Groot Kirsten , Aries Peer Malte , Haubitz Marion , Hellmich Bernhard , Lamprecht Peter , Thiel Jens
Published: January 2020

Die Granulomatose mit Polyangiitis (GPA) und die mikroskopische Polyangiitis (MPA) stellen als primäre nekrotisierende Kleingefäßvaskulitiden die häufigsten ANCA-assoziierten Vaskulitiden dar. Bei diesen, früher oft tödlich verlaufenden Erkrankungen kann heute durch eine Stadien-adaptierte Immunsuppression in den meisten Fällen eine Remission erzielt werden. Diese mündet jedoch nicht in eine Heilung oder medikamentenfreie Langzeitremission. Es bedarf deshalb einer remissionserhaltenden Therapie. Aktuelle randomisierte kontrollierte Studien zeigen, dass unter einer remissionserhaltenden Behandlung mit halbjährlich verabreichtem anti-B-Zell-Antikörper Rituximab weniger Rezidive auftreten als unter der bisherigen Standardmedikation mit Azathioprin bei vergleichbarem Nebenwirkungsprofil. Diese Daten führten 2018 zur Zulassung von Rituximab als remissionserhaltende Therapie der GPA und MPA. Unter einer solchen Rituximab-Therapie muss mit einer Immunglobulindepletion sowie späten Zytopenien mit begleitenden Infekten gerechnet werden. Leitlinien und Expertenempfehlungen zu Infektprophylaxen, Impfungen und Immunglobulinsubstitution werden in diesem Beitrag vorgestellt.
The band alignment of nonpolar m-plane ZnO1−xSx/Mg0.4Zn0.6O heterojunctions
Authors: Li Lei , Zhang Mi , Wang Qile , Li Pai , Li Mingkai , Lu Yinmei , Chen Hong , He Yunbin
Published: January 2020

Heterostructures such as heterojunctions, quantum wells, and superlattices are core components of advanced optoelectronic devices. Herein, we attempted the first investigations on the band alignment of nonpolar m-plane oriented ZnO1−xSx/Mg0.4Zn0.6O heterojunctions by X-ray photoelectron spectroscopy. All the heterojunctions were revealed to show a type-I band alignment, and the valence band offset (VBO; ΔEV) increased significantly, while the conduction band offset (ΔEC) decreased insignificantly with increasing S content in the ZnO1−xSx layer. Specifically, for the ZnO1−xSx/Mg0.4Zn0.6O heterojunctions with x = 0, 0.13, and 0.22, ΔEV (ΔEC) was determined to be 0.24 (0.22), 0.61 (0.17), and 0.79 (0.11) eV, respectively. The VBOs of ZnOS/MgZnO heterojunctions are significantly larger than those of heterojunctions involving only cation-substituted alloys (ZnO/MgZnO or ZnO/CdZnO) due to the opposite shift in the VB maximum of ZnOS and MgZnO with respect to ZnO. Knowing band alignment parameters of the ZnOS/MgZnO interface can provide a better understanding of the carrier transport mechanism and rational design of ZnO-based optoelectronic devices.
Absolute continuity of the spectrum in a twisted Dirichlet-Neumann waveguide
Authors: Briet Ph. , Dittrich J. , Krejčiřík D.
Published: January 2020

Quantum waveguides with the shape of a planar infinite straight strip and combined Dirichlet and Neumann boundary conditions on the opposite half-lines of the boundary are considered. The absence of the point as well as of the singular continuous spectrum is proved.
Machine learning based on reservoir computing with time-delayed optoelectronic and photonic systems
Authors: Chembo Yanne K.
Published: January 2020

The concept of reservoir computing emerged from a specific machine learning paradigm characterized by a three-layered architecture (input, reservoir, and output), where only the output layer is trained and optimized for a particular task. In recent years, this approach has been successfully implemented using various hardware platforms based on optoelectronic and photonic systems with time-delayed feedback. In this review, we provide a survey of the latest advances in this field, with some perspectives related to the relationship between reservoir computing, nonlinear dynamics, and network theory.
Dissipation and dynamics in ultrafast intersystem crossings
Authors: van Veenendaal Michel
Published: January 2020

The effects of dynamics and dissipation on ultrafast intersystem crossings are studied for a dissipative two-level system coupled to a local vibronic mode. A method of amplitude damping of the wave packet is presented that accounts better for the position of the wave packet and avoids spurious transitions between potential wells. It is demonstrated that Fermi’s golden rule, the typical semiquantitative approach to extract population transfer rates from potential landscapes, only holds under limited conditions. Generally, the effects of dynamics and dissipation lead to deviations from the expected exponential population transfer, strong changes in transfer times and total population transfer, and significant recurrence or “spill back” of the wave packet.
Flow control over a square cylinder using attached rigid and flexible splitter plate at intermediate flow regime
Authors: Sharma K. R. , Dutta S.
Published: January 2020

A detailed flow field behind a stationary square cylinder with attached rigid and flexible splitter plates has been studied using particle image velocimetry, constant temperature anemometry, and flow visualization techniques. A wide range of lengths of the splitter plate (L/B = 0–8) are considered, and their respective wake interference is reported. The investigation is carried out at an intermediate flow regime at three Reynolds numbers 600, 1000, and 2000 (based on blocking width “B” of the cylinder). The literature seriously lacks the information on a passive flow control of bluff body wakes in this flow regime. This study shows that the wake frequency and mean drag coefficient vary nonmonotonically to splitter plate lengths. The length of the splitter plate is a critical parameter, which, apart from flow control, can also bring a significant wake transition. At L/B > 3 to L/B = 4, strong secondary vortices are shed from the trailing edge. The shedding of the secondary vortex leads to a sudden shrinkage in the recirculation bubble and an increase in the periodicity of the unsteady flow. The onset of high amplitude flapping occurs in a flexible splitter plate (L/B = 3) at Re = 2000. The vortex shedding frequency becomes higher than the first mode natural frequency of the flexible splitter plate for this length and remains in the same regime for L/B > 3. The amplitude of flapping increases up to L/B = 5 and then again recedes. The high amplitude flapping of the flexible splitter plate adversely affects the mean drag coefficient of the bluff body.
Non-Gaussian subdiffusion of single-molecule tracers in a hydrated polymer network
Authors: Singh R. K. , Mahato Jaladhar , Chowdhury Arindam , Sain Anirban , Nandi Amitabha
Published: January 2020

Single molecule tracking experiments inside a hydrated polymer network have shown that the tracer motion is subdiffusive due to the viscoelastic environment inside the gel-like network. This property can be related to the negative autocorrelation of the instantaneous displacements at short times. Although the displacements of the individual tracers exhibit Gaussian statistics, the displacement distribution of all the trajectories combined from different spatial locations of the polymer network exhibits a non-Gaussian distribution. Here, we analyze many individual tracer trajectories to show that the central portion of the non-Gaussian distribution can be well approximated by an exponential distribution that spreads sublinearly with time. We explain all these features seen in the experiment by a generalized Langevin model for an overdamped particle with algebraically decaying correlations. We show that the degree of non-Gaussianity can change with the extent of heterogeneity, which is controlled in our model by the experimentally observed distributions of the motion parameters.
The micro-photoconductivity spectroscopy with the spectral capability extended to mid-infrared
Authors: Gong Bin , Zha Fang-Xing
Published: January 2020

A microphotoconductivity (μPC) spectroscopy is developed with an ordinary monochromator and halogen and SiN globar lamps. The instrument may cover a wide spectral range from visible to mid-infrared. For the μ-PC instrumentation, the improvement of signal-to-noise ratio is a crucial issue. We demonstrate that the employment of the Wheatstone bridge provides an effective solution. The instrument has been successfully applied to the narrow bandgap semiconductors InGaAs and HgCdTe, which show the optical band edges at the wavelengths of 2.35 µm and 5.0 µm at 82 K, respectively. The minimization of the light spot is influenced by the intensity of the light source, and the 45 W globar allows the performance of μPC with a light spot of 30 µm diameter for the spectral range of 2.0–3.5 µm, whereas the light spot of 60 µm diameter is necessarily used for the spectral range around 5.0 µm.
A study of the optical effect of plasma sheath in a negative ion source using IBSIMU code
Authors: George Anand , Kalvas Taneli , Melanson Stephane , Savard Nicolas , Potkins Dave , Dehnel Morgan , Broderick Neil G. R.
Published: January 2020

A plasma sheath inside an ion source has a strong focusing effect on the formation of an ion beam from the plasma. Properties of the beam depend on the shape and location of the plasma sheath inside the source. The most accessible experimental data dependent on the plasma sheath are the beam phase space distribution. Variation of beam emittance is a reflection of the properties of the plasma sheath, with minimum emittance for the optimal shape of the plasma sheath. The location and shape of the plasma sheath are governed by complex physics and can be understood by simulations using plasma models in particle tracking codes like IBSimu. In the current study, a model of the D-Pace’s TRIUMF licensed filament powered volume-cusp negative ion source is made using the IBSimu code. Beam emittance trends are compared between experiments and simulations.
Thermal annealing induced enhancement of room temperature magnetic memory effect in Fe-doped NiO nanoparticles
Authors: Gandhi Ashish Chhaganlal , Wu Sheng Yun
Published: January 2020

We report room temperature (RT) ferromagnetism and magnetic memory effect in Ni0.95Fe0.05O nanoparticles (NPs) synthesize by hydrothermal method followed by post-annealing in an ambient atmosphere. The temperature and time-dependent magnetization measurements show that the effect of post-annealing at higher temperatures leads to enhancement in the intraparticle interactions. The enhanced intraparticle interaction has provided additional magnetic anisotropy energy resulting in RT ferromagnetic (FM) properties and enhanced magnetic memory effect. The findings from this study will be useful for the development and understanding of RT FM materials to facilitate the integration of spintronic devices.
Experimental verification and electromagnetic characteristics analysis of wound-rotor synchronous generator using magnetic equivalent circuit method
Authors: Kwon Do-Yun , Bang Tae-Kyoung , Kim Chang-Woo , Shin Kyung-Hun , Choi Jang-Young
Published: January 2020

This paper presents the magnetic field characteristics of a synchronous generator with a salient pole structure using a simple magnetic equivalent circuit (MEC) method. This method aims to reduce the analysis time considering nonlinearity. By using the MEC, a solution for the magnetic flux density is obtained. The linkage flux is derived using the magnetic flux density of the air gap and the armature voltage is obtained. Additionally, results obtained using the finite-element method and MEC are validated against experimental data.
Anomalous solution softening by unique energy balance mediated by kink mechanism in tungsten-rhenium alloys
Authors: Tsuru Tomohito , Wakeda Masato , Suzudo Tomoaki , Itakura Mitsuhiro , Ogata Shigenobu
Published: January 2020

Nucleation of transmutation products such as rhenium (Re) and osmium (Os) is a central issue contributing to changes in mechanical properties under neutron irradiation in fusion reactors. In particular, Re solutes in tungsten (W) not only affect hardening via radiation-induced precipitation but also have a notable softening effect. We explored the softening/strengthening behaviors of various solutes in a W matrix by density functional theory (DFT) calculations combined with a solid solution model. Our DFT calculations of the solutes show a clear trend in the interaction energy between different solutes and screw dislocations, which also influences the solid solution behavior. These predictions, based on a solid solution model and DFT calculations, reasonably reproduce the complex softening/strengthening behavior as a function of temperature and solute concentration. Notably, solutes such as Re have relatively weak attractive interactions and do not markedly influence the pinning effect; however, such solutes can reduce the energy barrier for kink pair nucleation. We conclude that this specific balance is the origin of macroscopic solid solution softening in dilute body-centered cubic alloys.
A vortex identification method based on local fluid rotation
Authors: Tian Shuling , Fu Hao , Xia Jian , Yang Yong
Published: January 2020

In this work, a vortex identification method is developed by analyzing the physical meaning of the local rotation of fluid elements. It is shown that a point is locally rotational when the velocity gradient tensor at the point has a pair of complex eigenvalues. The local rotation can be represented by a so called vortex vector. The direction of the vortex vector is defined as that of the local fluid rotation axis, which is parallel to the eigenvector of velocity gradient tensor corresponding to the real eigenvalue. The magnitude is evaluated as the twice of the minimum angular velocity around the point among all azimuth in the plane perpendicular to the vortex vector. Based on the local fluid rotation, a vortex is identified as a connected region where the vortex vector at each point is not equal to zero. The vortex identification method is validated by applying it to Reynolds-averaged Navier-Stokes data and direct numerical simulation data. The results reveal that the method can fully describe the complex structures of vortices.
Catalysis on oxidized ferroelectric surfaces—Epitaxially strained LaTiO2N and BaTiO3 for photocatalytic water splitting
Authors: Vonrüti Nathalie , Aschauer Ulrich
Published: January 2020

Surface properties of ferroelectrics are promising for catalysis due to the spontaneous electric polarization that can be reversed by an applied electric field. While several theoretical studies show different catalytic activities for differently polarized ferroelectric surfaces at zero electric potential, little work was devoted to catalysis on ferroelectric surfaces at higher electric potentials. Under these conditions that are relevant for photocatalytic experiments and applications, surfaces are usually oxidized. Using density functional theory calculations, we show for LaTiO2N and BaTiO3 that this oxidation heavily impacts and even determines the electronic properties of the catalyst surface and therefore leads to similar reaction free energies for the catalytic steps of the oxygen evolution reaction, irrespective of the bulk polarization. This is opposed to experimental studies, which found different activities for differently polarized catalyst surface domains under oxidizing conditions. We therefore conclude that the experimentally observed activity difference does not originate from the surface polarization following the bulk polarization, but rather from different bulk polarization directions leading to different adsorbate coverages or even surface reconstructions.
An analysis of radical diffusion in ionic liquids in terms of free volume theory
Authors: Merunka Dalibor , Peric Miroslav
Published: January 2020

The Heisenberg spin exchange–dipole-dipole separation method was used to measure the translational diffusion coefficients of the 14N-labeled perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (14N-pDTEMPONE) nitroxide spin probe as a function of temperature in two methylimidazolium ionic liquid series, one based on the tetrafluoroborate (BF4) anion and another one on the bis(trifluoromethane)sulfonimide (TFSI, Tf2N) anion. The obtained translational diffusion coefficients of 14N-pDTEMPONE were analyzed in terms of the Cohen–Turnbull free volume theory. It was found that the Cohen-Turnbull theory describes, exceptionally well, the translational diffusion of 14N-pDTEMPONE in all the ionic liquids in the measured temperature range. In addition, the Cohen-Turnbull theory was applied to the viscosity and self-diffusion coefficients of the cation and anion—taken from literature—in the same ionic liquids. The critical free volume for the self-diffusion of the cation and anion in a given ionic liquid is the same, which suggests that the diffusion of each ionic pair is coordinated. The critical free volumes for the 14N-pDTEMPONE diffusion, self-diffusion, and viscosity for a given cation were about 20% greater in the TFSI based ionic liquids than in the BF4 based ionic liquids. It appears that the ratio of the critical free volumes for a given cation between the two series correlates with the ratio of their densities.
Phylogeography of southern brown and golden bandicoots: implications for the taxonomy and distribution of endangered subspecies and species
Authors: Cooper Steven J. B. , Ottewell Kym , MacDonald Anna J. , Adams Mark , Byrne Margaret , Carthew Susan M. , Eldridge Mark D. B. , Li You , Pope Lisa C. , Saint Kathleen M. , Westerman Michael
Published: January 2020

Southern brown (Isoodon obesulus) and golden (Isoodon auratus) bandicoots are iconic Australian marsupials that have experienced dramatic declines since European settlement. Conservation management programs seek to protect the remaining populations; however, these programs are impeded by major taxonomic uncertainties. We investigated the history of population connectivity to inform subspecies and species boundaries through a broad-scale phylogeographic and population genetic analysis of Isoodon taxa. Our analyses reveal a major east–west phylogeographic split within I. obesulus/I. auratus, supported by both mtDNA and nuclear gene analyses, which is not coincident with the current species or subspecies taxonomy. In the eastern lineage, all Tasmanian samples formed a distinct monophyletic haplotype group to the exclusion of all mainland samples, indicative of long-term isolation of this population from mainland Australia and providing support for retention of the subspecific status of the Tasmanian population (I. o. affinis). Analyses further suggest that I. o. obesulus is limited to south-eastern mainland Australia, representing a significant reduction in known range. However, the analyses provide no clear consensus on the taxonomic status of bandicoot populations within the western lineage, with further analyses required, ideally incorporating data from historical museum specimens to fill distributional gaps.
Hemidesmosomes modulate force generation via focal adhesions
Authors: Wang Wei , Zuidema Alba , te Molder Lisa , Nahidiazar Leila , Hoekman Liesbeth , Schmidt Thomas , Coppola Stefano , Sonnenberg Arnoud
Published: January 2020

Hemidesmosomes are specialized cell-matrix adhesion structures that are associated with the keratin cytoskeleton. Although the adhesion function of hemidesmosomes has been extensively studied, their role in mechanosignaling and transduction remains largely unexplored. Here, we show that keratinocytes lacking hemidesmosomal integrin α6β4 exhibit increased focal adhesion formation, cell spreading, and traction-force generation. Moreover, disruption of the interaction between α6β4 and intermediate filaments or laminin-332 results in similar phenotypical changes. We further demonstrate that integrin α6β4 regulates the activity of the mechanosensitive transcriptional regulator YAP through inhibition of Rho–ROCK–MLC– and FAK–PI3K–dependent signaling pathways. Additionally, increased tension caused by impaired hemidesmosome assembly leads to a redistribution of integrin αVβ5 from clathrin lattices to focal adhesions. Our results reveal a novel role for hemidesmosomes as regulators of cellular mechanical forces and establish the existence of a mechanical coupling between adhesion complexes.
Mps1-mediated release of Mad1 from nuclear pores ensures the fidelity of chromosome segregation
Authors: Cunha-Silva Sofia , Osswald Mariana , Goemann Jana , Barbosa João , Santos Luis M. , Resende Pedro , Bange Tanja , Ferrás Cristina , Sunkel Claudio E. , Conde Carlos
Published: January 2020

The spindle assembly checkpoint (SAC) relies on the recruitment of Mad1-C-Mad2 to unattached kinetochores but also on its binding to Megator/Tpr at nuclear pore complexes (NPCs) during interphase. However, the molecular underpinnings controlling the spatiotemporal redistribution of Mad1-C-Mad2 as cells progress into mitosis remain elusive. Here, we show that activation of Mps1 during prophase triggers Mad1 release from NPCs and that this is required for kinetochore localization of Mad1-C-Mad2 and robust SAC signaling. We find that Mps1 phosphorylates Megator/Tpr to reduce its interaction with Mad1 in vitro and in Drosophila cells. Importantly, preventing Mad1 from binding to Megator/Tpr restores Mad1 accumulation at kinetochores, the fidelity of chromosome segregation, and genome stability in larval neuroblasts of mps1-null mutants. Our findings demonstrate that the subcellular localization of Mad1 is tightly coordinated with cell cycle progression by kinetochore-extrinsic activity of Mps1. This ensures that both NPCs in interphase and kinetochores in mitosis can generate anaphase inhibitors to efficiently preserve genomic stability.
Absence of GP130 cytokine receptor signaling causes extended Stüve-Wiedemann syndrome
Authors: Chen Yin-Huai , Grigelioniene Giedre , Newton Phillip T. , Gullander Jacob , Elfving Maria , Hammarsjö Anna , Batkovskyte Dominyka , Alsaif Hessa S. , Kurdi Wesam I.Y. , Abdulwahab Firdous , Shanmugasundaram Veerabahu , Devey Luke , Bacrot Séverine , Brodszki Jana , Huber Celine , Hamel Ben , Gisselsson David , Papadogiannakis Nikos , Jedrycha Katarina , Gürtl-Lackner Barbara , Chagin Andrei S. , Nishimura Gen , Aschenbrenner Dominik , Alkuraya Fowzan S. , Laurence Arian , Cormier-Daire Valérie , Uhlig Holm H.
Published: January 2020

The gene IL6ST encodes GP130, the common signal transducer of the IL-6 cytokine family consisting of 10 cytokines. Previous studies have identified cytokine-selective IL6ST defects that preserve LIF signaling. We describe three unrelated families with at least five affected individuals who presented with lethal Stüve-Wiedemann–like syndrome characterized by skeletal dysplasia and neonatal lung dysfunction with additional features such as congenital thrombocytopenia, eczematoid dermatitis, renal abnormalities, and defective acute-phase response. We identified essential loss-of-function variants in IL6ST (a homozygous nonsense variant and a homozygous intronic splice variant with exon skipping). Functional tests showed absent cellular responses to GP130-dependent cytokines including IL-6, IL-11, IL-27, oncostatin M (OSM), and leukemia inhibitory factor (LIF). Genetic reconstitution of GP130 by lentiviral transduction in patient-derived cells reversed the signaling defect. This study identifies a new genetic syndrome caused by the complete lack of signaling of a whole family of GP130-dependent cytokines in humans and highlights the importance of the LIF signaling pathway in pre- and perinatal development.
Measuring Subjective Ideological Disagreement with the US Supreme Court
Authors: Nelson Michael J. , Gibson James L.
Published: January 2020

Conventional wisdom suggests that judicial legitimacy should be relatively unaffected by satisfaction with the ideological direction of judicial policy making. Recent studies challenge this assertion. The key to resolving this conundrum is estimating individual-level satisfaction with the ideological direction of judicial policy making reliably and validly. We examine the accuracy of several common measures of the concept. We find that 40% of the respondents repudiate their own scores on these measures. With this much systematic measurement error in such an important independent variable, the question of whether the Supreme Court’s institutional legitimacy is conditional on ideological agreement with its decisions must be reexamined.
Triangular color codes on trivalent graphs with flag qubits
Authors: Chamberland Christopher , Kubica Aleksander , Yoder Theodore J , Zhu Guanyu
Published: January 2020

The color code is a topological quantum error-correcting code supporting a variety of valuable fault-tolerant logical gates. Its two-dimensional version, the triangular color code, may soon be realized with currently available superconducting hardware despite constrained qubit connectivity. To guide this experimental effort, we study the storage threshold of the triangular color code against circuit-level depolarizing noise. First, we adapt the Restriction Decoder to the setting of the triangular color code and to phenomenological noise. Then, we propose a fault-tolerant implementation of the stabilizer measurement circuits, which incorporates flag qubits. We show how information from flag qubits can be used in an efficient and scalable way with the Restriction Decoder to maintain the effective distance of the code. We numerically estimate the threshold of the triangular color code to be 0.2%, which is competitive with the thresholds of other topological quantum codes. We also prove that 1-flag stabilizer measurement circuits are sufficient to preserve the full code distance, which may be used to find simpler syndrome extraction circuits of the color code.
About the Danger of Vibration Combustion in Gas Explosions in the Room
Authors: Polandov Iu H , Korolchenko A D
Published: January 2020

In recent years, in experimental gas explosions in open volumes, such a phenomenon as vibration combustion has been recorded or, as they sometimes say, flame-acoustic combustion, or simply combustion, but accompanied by acoustic gas oscillations. Generally speaking, this type of combustion was known for a long time in the 19th century, from the time of Higgins and Rijke, and acquired the poetic name “singing flame”. However, at the onset of gas turbine and rocket engines, this phenomenon manifested itself in their combustion chambers and was designated as a whip, as it resulted in structural damage. But the vibration combustion is known not only for the destructive force, but also for the intensification of fuel combustion process in high-duty furnaces.
Modeling strain processes in earth dams with account for inhomogeneous features of a structure
Authors: Sultanov T Z , Bestuzheva A S , Yuldashev B Sh , Urinov B X , Numonov A T
Published: January 2020

A calculation procedure, results of the stress-strain and strength state studies of earth dams under the effect of their own weight and hydrostatic pressure of water are given in the paper in a generalized plane-deformed state, taking into account real geometry of a dam, design features and inhomogeneous properties of the structure materials. Three different earth dams with their design features are considered in the paper. Potential dangerous zones (in the dam body) with reduced strength characteristics of soil are investigated and revealed at various schemes of dam construction and the level of reservoir filling.

The reliability of the methods, algorithm and the accuracy of the results obtained are verified by solving test problems.
Analytical solution for longitudinal and transverse loading of elastic-plastic beam
Authors: Elenitskiy E
Published: January 2020

In this article, based on equations of equilibrium of forces applied in a rectangular cross section, subjected to elastic-plastic deformations differential equations were obtained and a new exact solution for a single-span straight beam under the action of longitudinal and transverse loads was built. All the components of the stress-strain state, borders of elastic-plastic zones, as well as expressions for the unit cross-section stiffness were explicitly defined.
Decrease of radon permeability in cement concrete and solutions
Authors: Tarasov I V , Nazirov R A , Tarasov A V , Loktev D A , Dobrosmyslov S S
Published: January 2020

The article presents special research aimed at the estimation of radon permeability change in cement-sand solution after applying a padding layer of the gypsum on its surface during the process of forming the additional layer of gypsum paste to decrease radon permeability of cement concretes and solutions.
Space-based quantification of per capita CO2 emissions from cities
Authors: Wu Dien , Lin John C , Oda Tomohiro , Kort Eric A
Published: January 2020

Urban areas are currently responsible for ∼70% of the global energy-related carbon dioxide (CO2) emissions, and rapid ongoing global urbanization is increasing the number and size of cities. Thus, understanding city-scale CO2 emissions and how they vary between cities with different urban densities is a critical task. While the relationship between CO2 emissions and population density has been explored widely in prior studies, their conclusions were sensitive to inconsistent definitions of urban boundaries and the reliance upon CO2 emission inventories that implicitly assumed population relationships. Here we provide the first independent estimates of direct per capita CO2 emissions (E
pc) from spaceborne atmospheric CO2 measurements from the Orbiting Carbon Observatory-2 (OCO-2) for a total 20 cities across multiple continents. The analysis accounts for the influence of meteorology on the satellite observations with an atmospheric model. The resultant upwind source region sampled by the satellite serves as an objective urban extent for aggregating emissions and population densities. Thus, we are able to detect emission ‘hotspots’ on a per capita basis from a few cities, subject to sampling restrictions from OCO-2. Our results suggest that E
pc declines as population densities increase, albeit the decrease in E
pc is partially limited by the positive correlation between E
pc and per capita gross domestic product. As additional CO2-observing satellites are launched in the coming years, our space-based approach to understanding CO2 emissions from cities has significant potential in tracking and evaluating the future trajectory of urban growth and informing the effects of carbon reduction plans.
Increasing of Aceh’s patchouli production with technology of bio-fertilizer local specific mycorrhizal strains in Entisols
Authors: Syafruddin  , Syakur  , Nurahmi E , Hayati E , Nurhayati  , Susanti E
Published: January 2020

Aceh’s patchouli is one of the superior local commodities, and its growth and yield could be improved in various means. One way to increase the patchouli production can be done by using bio-fertilizer mycorrhizal local strain. The purpose of this research was to study effect of bio-fertilizer mycorrhizal local specific strain on the growth and yield of patchouli in Entisols. We conducted two experiment. The first experiment was the propagation technique of mycorrhizae on Entisols soil and the second experiment the test of the fertilizer on a greenhouse pot scale for the growth of patchouli seedlings. The research was arranged by a non-factorial randomized block design with three replications. The investigated factor was the bio-fertilizer mycorrhizal from local specific strain with four levels, i.e. M0 (without mycorrhizae), M1 (Glomus mosseae) M2 (Gigaspora sp) and M3 (Mixing between Glomus mosseae and Gigaspora sp). The variety of patchouli used in this study was the Tapak Tuan variety. The observed parameters were seedling height and seedling diameter of patchouli at 45, 60 days after planting; additionally the parameter of patchouli yields consist of number of leaves, number of branches and weight of leaves were observed at 90 days after planting, and root colonization by mycorrhizae. The results showed that mixed mycorrhizal strains between Glomus mosseae + Gigaspora sp contributed to the best marks for increasing growth and yield of seedling patchouli in Entisolss. The similar trend result was also found in the root colonization by mycorrhizae. The strain of mycorrhizal of Gigaspora sp application was not effective for increasing the growth and yield of Aceh’s patchouli in Entisols.