bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐gain low‐RCS slot antenna array based on checkerboard surface
Authors: Jiang Hao , Xue Zhenghui , Zeng Qingyun , Li Weiming , Ren Wu
Published: October 2017

In‐band and out‐of‐band radar cross‐section reduction (RCSR) as well as gain enhancement for a slot antenna array is presented. The checkerboard surface (CS), combining an electromagnetic band gap structure and a metallic grounded slab, is adopted to realise a wideband RCSR. The analysis indicates a 10 dB RCSR of the CS compared with the perfect electric conductor surface can be achieved over 60% frequency bandwidth. Then, the designed CS is placed on the top surface of the 2 × 2 slot antenna array, and the measured results reveal that the proposed slot array possesses in‐band and out‐of‐band RCSR from 5 to >12 GHz for both co‐ and cross‐polarisations. Apart from the wideband RCSR, the gain enhancement is about 2.1 dB compared with the slot antenna array without the CS.
Application of GEP to investigate the imbalance faults in direct‐drive wind turbine using generator current signals
Authors: Malik Hasmat , Mishra Sukumar
Published: October 2017

This study proposes a novel wind turbine generator (WTG) imbalance fault classifier using gene expression programming (GEP). Proposed GEP fault classifier is able to achieve very high classification accuracy with relatively small number of samples. Ours is a first attempt at designing a WTG imbalance fault identifier using GEP for fault segregation. The identifier does not assume prior knowledge of WTG model. Raw current data of permanent magnet synchronous generator stator side are processed through empirical mode decomposition to generate 16 intrinsic mode functions or IMFs. Classifier employs the J48 algorithm to further prune these 16 IMFs to eight most relevant input variables which serve as inputs to the GEP imbalance fault classifier. The authors compare performance of the proposed GEP classifier with other contemporary artificial intelligence (AI) based classifiers such as neural networks and support vector machines. Simulation results and performance comparison against other AI approaches elucidate that the proposed GEP‐based identifier could serve as an important tool for WTG fault diagnosis.
The Migrate project: the challenges of operating a transmission grid with only inverter‐based generation. A grid‐forming control improvement with transient current‐limiting control
Authors: Denis Guillaume , Prevost Thibault , Debry Marie‐Sophie , Xavier Florent , Guillaud Xavier , Menze Andreas
Published: October 2017

Renewable generation is mainly connected through converters. Even if they provide more and more ancillary services to the grid, these may not be sufficient for extremely high penetrations. As the share of such generating units is growing rapidly, some synchronous areas could in the future occasionally be operated without synchronous machines. In such conditions, system behaviour will dramatically change, but stability will still have to be ensured with the same level of reliability as today. To reach this ambitious goal, the control of inverters will have to be changed radically. Inverters will need to move from following the grid to leading the grid behaviour, both in steady state and during transients. This new type of control brings additional issues on converters that are addressed in this study. A solution is proposed to allow a stable operation of the system together with a limited solicitation of inverters during transients.
Explicit bipercentile parameter estimation of compound‐Gaussian clutter with inverse gamma distributed texture
Authors: Shui Peng‐Lang , Yu Han , Shi Li‐Xiang , Yang Chun‐Jiao
Published: October 2017

Compound‐Gaussian model with inverse Gamma distributed texture is a powerful tool to characterise heavy‐tailed sea clutter. The parameters of the model need to be estimated in advance or online to assist the optimum detection. Moment‐based estimators are suitable for a limited range of shape parameter, the maximum likelihood (ML) estimator lacks an explicit expression and fast iterative solution, and the method of log‐cumulants (MoLC) can work in all cases but is not good for large shape parameters. Moreover, their performance is sensitive to outliers in samples. Explicit bipercentile estimators are proposed to estimate the scale and shape parameters, which are computationally efficient and outliers robust. Without outliers in samples, the bipercentile estimators are comparable with the moment‐based estimators and MoLC estimator in performance except when the number of samples is very small. With outliers in samples, the bipercentile estimators are much better than the moment‐based and ML estimators. Moreover, the ability of the bipercentile estimators is verified by measured sea clutter data.
CMOS integrated sensor circuit for temperature measurement based on 50 nm technology
Authors: Liu Jihong , Sun Yingying , Shi Chengzhi
Published: October 2017

A fully‐integrated complementary metal–oxide semiconductor sensor using NPN transistors for temperature measurement is presented. The main purpose of the device is to monitor the temperature for implanted integrated circuits and to ensure the safe operation by monitoring the temperature on‐chip. This study adopted a behavioural simulator that uses LTSPICE for a temperature sensor for performing the rapid and accurate simulation. It is advantageous in 50 nm technique to design the circuits. The integrated sensor circuit consists of a bias circuit, an operational amplifier, and a thermal module. A high sensitivity of 5.9 mV/°C in the output voltage circuit has been measured, the linear dependence of voltage drop across the bipolar junction transistor on temperature, in a range from −30 to 125°C, has been used for thermal sensing.
Interrupted Pummerer Reaction in Latent/Active Glycosylation
Authors: Meng Lingkui , Zeng Jing , Wan Qian
Published: October 2017

A latent/active glycosylation strategy is efficient for rapid ­assembly of oligosaccharides. We recently developed novel OPTB/OPSB and SPTB/SPSB glycosides as two pairs of latent/active glycosyl donors. The active OPSB and SPSB glycosyl donors are efficiently activated by Tf2O via an interrupted Pummerer reaction mechanism. In this account, the design, developments, mechanism studies and applications of these new glycosylation methodologies are described.

1 Introduction

2 Conceiving Ideas

3 Synthesis of OPSB and SPSB Glycosides

4 Substrate Scope

5 Application in the Synthesis of Natural Products

6 Conclusion
Iodine Monoacetate for Efficient Oxyiodinations of Alkenes and Alkynes
Authors: Wirth Thomas , Hokamp Tobias , Storm Alena , Yusubov Mekhman
Published: October 2017

A novel and inexpensive, environmentally friendly method for the preparation of iodine monoacetate is presented using iodine and Oxone in acetic acid/acetic anhydride. The reagent is used in a highly efficient approach for the regio- and diastereoselective iodo­acetoxylation of alkenes and alkynes in a simple one-pot process.
Catalytic α-Arylation of Ketones with Heteroaromatic Esters
Authors: Yamaguchi Junichiro , Isshiki Ryota , Takise Ryosuke , Itami Kenichiro , Muto Kei
Published: October 2017

Heteroaromatic esters were found to be applicable as an arylating agent for the Pd-catalyzed α-arylation of ketones in a decarbonylative fashion. The use of our in-house ligand, dcypt, enabled this unique bond formation. Considering the ubiquity and low cost of ­aromatic esters, the present work will allow for rapid access to valuable α-aryl carbonyl compounds.
Visible-Light-Induced Chemoselective Synthesis of α-Chloro and Vinyl Sulfones by Sulfonylation of Alkenes
Authors: Niu Teng-fei , Ni Bang-qing , Lin Dan , Xue Lin-shuang , Jiang Ding-yun
Published: October 2017

Direct sulfonylation between alkenes and sulfonyl chloride was achieved at room temperature by a visible-light-induced photo­redox process. This method allows the chemoselective synthesis of α-chloro and vinyl sulfone derivatives with moderate to high yields. The selectivity of the reaction was fully controlled by the electronic properties of the alkenes.
Auditive Verarbeitungs- und Wahrnehmungsstörung: Ist die Diagnose schon bei Erstklässlern möglich?
Authors: Kiese-Himmel Christiane , Nickisch Andreas , Werner Franziska
Published: October 2017

Hintergrund Signifikante Leistungsunterschiede zwischen Kindern mit und ohne auditive Verarbeitungs- und Wahrnehmungsstörungen (AVWS)
im 2., 3. und 4. Grundschuljahr wurden in einer eklektischen AVWS-Testbatterie für die meisten Diagnoseinstrumente festgestellt. Die
aktuelle Studie erfolgte mit der Fragestellung, ob dies auch für Kinder der 1. Schulklassenstufe zutrifft.

Material und Methoden Leistungen von 41 Kindern mit und von 37 ohne AVWS im 1. Regelgrundschuljahr (Alter: 6–8 Jahre) wurden in 14
spezifisch auditiven Tests miteinander verglichen.

Ergebnisse Statistisch signifikante Gruppenunterschiede wurden in 12 Diagnoseinstrumenten aufgedeckt; lediglich in 2 PaTSy-Subtests
(Tonfrequenzen; Tonintensitäten) war das nicht der Fall. Bzgl. der monauralen Ordnungsschwelle blieb die Signifikanz nach
Bonferroni-Korrektur knapp erhalten. Non-AVWS-Kinder bewältigten die PaTSy-Subtests in 86–89 %, AVWS-Kinder in 73–83 % aller Fälle. Die
Testwerte von Jungen bzw. Mädchen mit AVWS waren im Vergleich zu denen von Jungen bzw. Mädchen ohne AVWS durchweg reduziert.

Schlussfolgerungen Auch Erstklässler mit „AVWS“ ließen sich von solchen ohne „AVWS“ statistisch signifikant unterscheiden. In der
Tendenz waren bei Erstklässlern mit AVWS dieselben Leistungen gemindert wie bei Grundschülern in höheren Klassenstufen. Der Einsatz
sprachfreier audiologischer Verfahren zur klinischen Diagnose von AVWS erscheint für die Altersgruppe 6–8 Jahre jedoch fragwürdig.
The populism of the Alternative for Germany (AfD): an extended Essex School perspective
Authors: Kim Seongcheol
Published: October 2017

This paper seeks to draw on the tools of Ernesto Laclau’s theory of discourse, hegemony and populism as well as recent Essex School work on populism to examine the discourse of the Alternative for Germany (AfD) and, in the process, come closer to a more systematic understanding of nature and limits ofright-wingpopulism as well as the interplay and distinction between populist and non-populist discursive logics more generally. The paper situates itself in the context of existing Essex School work that has distinguished populism from institutionalism—and, more recently, from nationalism —in terms of either the length of the equivalential chain or the centrality of “the people” as nodal point in addition to the degree of antagonistic division between “people” and “power.” Building on this latter strand in the recent work of Yannis Stavrakakis and others, this paper proposes a formal distinction betweenpopulismandreductionismas internal to Laclau’s theory of populism. Reductionism, it is argued, tends to reduce “the people” onto a differential particularity that setsa priorilimits on the equivalential chain as opposed to constructing it as atendentially empty signifierattached to anopen-endedchain—producing a tendentialclosureof the equivalential chain and thus undercutting the primacy of the logic of equivalence that is fundamental to Laclau’s understanding of populism and subsequent Essex School applications of it. It is argued that predominantly ethno-, cultural- or nativist-reductionist discourses may nonetheless deploy a populist logic ofpartial openingsin the equivalential chain, especially through the selective equivalential incorporation of sexual or ethno-linguistic minorities against a common (often “Islamic”) constitutive outside. This is demonstrated empirically in a discourse analysis of the AfD and its development from a “competition populism” into an ethno-culturally reductionist conception of “the people” coexisting with partial openings in relation to the lesbian, gay, bisexual, and transgender (LGBT) community and Russian-Germans in the Berlin context in particular.
An optical fiber Bragg grating and piezoelectric ceramic voltage sensor
Authors: Yang Qing , He Yanxiao , Sun Shangpeng , Luo Mandan , Han Rui
Published: October 2017

Voltage measurement is essential in many fields like power grids, telecommunications, metallurgy, railways, and oil production. A voltage-sensing unit, consisting of fiber Bragg gratings (FBGs) and piezoelectric ceramics, based on which an optical over-voltage sensor was proposed and fabricated in this paper. No demodulation devices like spectrometer or Fabry-Perot filter were needed to gain the voltage signal, and a relatively large sensing frequency range was acquired in this paper; thus, the cost of the sensing system is more acceptable in engineering application. The voltage to be measured was directly applied to the piezoelectric ceramic, and deformation of the ceramics and the grating would be caused because of the inverse piezoelectric effect. With a reference grating, the output light intensity change will be caused by the FBG center wavelength change; thus, the relationship between the applied voltage and the output light intensity was established. Validation of the sensor was accomplished in the frequency range from 50 Hz to 20 kHz and switching impulse waves with a test platform; good linearity of the input-output characteristic was achieved. A temperature validation test was completed, showing that the sensor maintains good temperature stability. Experimental results show that the optical over-voltage sensor can be used for voltage monitoring, and if applied with a voltage divider, the sensor can be used to measure high voltage.
Inception threshold conditions for positive dc corona in a rod-plane electrode at low atmospheric temperatures
Authors: Yi Yong , Tang Wenxi , Chen Zhengying , Wang Liming
Published: October 2017

The effects of low temperature on the inception threshold conditions of positive dc corona in a rod-plane electrode are investigated. The low-temperature platform, including the refrigeration system, air drying system, and inception threshold measurement system, is used to research the salient inception condition at a wide range of temperatures. This paper also attempts to use the numerical inception model to understand the effects of temperature on ionization coefficient, charge density, primary avalanche length, and radius. In a wide range of temperatures, the inception electric field strength is evaluated through approximate empirical formulas and a numerical model. Experimental results of corona inception are given for temperatures ranging from –80 °C to 40 °C, radii from 0.2 to 1.6 cm, and 20% relative humidity of air. The comparisons between the calculations and experiments of inception voltages under different temperatures are presented. Experimental results are consistent with inception corona voltages being determined by theoretical predictions of photoionization effects producing electron avalanche sizes greater than those produced by net ionization and attachment collisions. It is found that the inception electric field and the inception voltage are pronouncedly influenced by atmospheric temperature.
Large-amplitude dust acoustic shocklets in non-Maxwellian dusty plasmas
Authors: Ali S. , Naeem Ismat , Mirza Arshad M.
Published: October 2017

The formation and propagation of fully nonlinear dust-acoustic (DA) waves and shocks are studied in a non-Maxwellian thermal dusty plasma which is composed of Maxwellian electrons and nonthermal energetic ions with a neutralizing background of negatively charged dust grains. For this purpose, we have solved dust dynamical equations along with quasineutrality equation by using a diagonalization matrix technique. A set of two characteristic wave equations is obtained, which admits both analytical and numerical solutions. Taylor expansion in the small-amplitude limit (Φ≪1) leads to nonlinear effective phase and shock speeds accounting for nonthermal energetic ions. It is numerically shown that DA pulses can be developed into DA shocklets involving the negative electrostatic potential, dust fluid velocity, and dust number density. These structures are significantly influenced by the ion-nonthermality, dust thermal correction, and temporal variations. However, the amplitudes of solitary and shock waves are found smaller in case of Cairns-distributed ions as compared to Kappa-distributed ions due to smaller linear and nonlinear effective phase speeds that cause smaller nonlinearity effects. The present results should be useful for understanding the nonlinear characteristics of large-amplitude DA excitations and nonstationary shocklets in a laboratory non-Maxwellian dusty plasma, where nonthermal energetic ions are present in addition to Maxwellian electrons.
Lattice Boltzmann simulation of shear-induced particle migration in plane Couette-Poiseuille flow: Local ordering of suspension
Authors: Chun Byoungjin , Kwon Ilyoung , Jung Hyun Wook , Hyun Jae Chun
Published: October 2017

The shear-induced migration of concentrated non-Brownian monodisperse suspensions in combined plane Couette-Poiseuille (C-P) flows is studied using a lattice Boltzmann simulation. The simulations are mainly performed for a particle volume fraction of ϕbulk = 0.4 and H/a = 44.3, 23.3, where H and a denote the channel height and radius of suspended particles, respectively. The simulation method is validated in two simple flows, plane Poiseuille and plane Couette flows. In the Poiseuille flow, particles migrate to the mid-plane of the channel where the local concentration is close to the limit of random-close-packing, and a random structure is also observed at the plane. In the Couette flow, the particle distribution remains in the initial uniform distribution. In the combined C-P flows, the behaviors of migration are categorized into three groups, namely, Poiseuille-dominant, Couette-dominant, and intermediate regimes, based on the value of a characteristic force, G, where G denotes the relative magnitude of the body force (P) against the wall-driving force (C). With respect to the Poiseuille-dominant regime, the location of the maximum concentration is shifted from the mid-plane to the lower wall moving in the same direction as the external body force, when G decreases. With respect to the Couette-dominant regime, the behavior is similar to that of a simple shear flow with the exception that a slightly higher concentration of particles is observed near the lower wall. However, with respect to the intermediate value of G, several layers of highly ordered particles are unexpectedly observed near the lower wall where the plane of maximum concentration is located. The locally ordered structure is mainly due to the lateral migration of particles and wall confinement. The suspended particles migrate toward a vanishingly small shear rate at the wall, and they are consequently layered into highly ordered two-dimensional structures at the high local volume fraction.
Generation of ion acoustic solitary waves through wave breaking in superthermal plasmas
Authors: Lotekar Ajay , Kakad Amar , Kakad Bharati
Published: October 2017

Space plasmas provide abundant evidence of a highly energetic particle population that results in a long-tailed non-Maxwellian distribution. Such plasmas can be effectively modeled with kappa distribution. The superthermal population in the tail of kappa distribution can have significant effects on the wave dynamical processes. We perform the fluid simulations to examine the effects of superthermal populations on the breaking of the electrostatic ion-acoustic (IA) wave, which is the most fundamental mode, existing in the unmagnetized plasmas. We construct a fluid model for exciting IA waves by employing a kappa distribution function for the superthermal population of electrons along with inertial cold ions (protons). We focused on the nonlinear excitations; in the form of ion acoustic solitary wave (IASW) structures formed through the process of wave breaking, and investigated the role of superthermal electron population in the initiation of the steepening, wave breaking, and propagation characteristics of the IASWs in plasma. From the output of the simulation, we established the criteria for the steepening time based on the variations in the phase velocity of the IASWs. Furthermore, we examined the maximum ponderomotive potential and ponderomotive frequency during the wave breaking process. We found that the time corresponding to the peak in the maximum ponderomotive potential is the time of the initialization of the wave breaking process. We present a detailed investigation of the role of the ponderomotive forces acting on the plasma at each time step, which explains the physics of the wave breaking in nonthermal plasmas.
Intermittency of quantum turbulence with superfluid fractions from 0% to 96%
Authors: Rusaouen E. , Chabaud B. , Salort J. , Roche P.-E.
Published: October 2017

The intermittency of turbulent superfluid helium is explored systematically in a steady wake flow from 1.28 K up to T>2.18K using a local anemometer. This temperature range spans relative densities of superfluids from 96% down to 0%, allowing us to test numerical predictions of enhancement or depletion of intermittency at intermediate superfluid fractions. Using the so-called extended self-similarity method, scaling exponents of structure functions have been calculated. No evidence of temperature dependence is found on these scaling exponents in the upper part of the inertial cascade, where turbulence is well developed and fully resolved by the probe. This result supports the picture of a profound analogy between classical and quantum turbulence in their inertial range, including the violation of self-similarities associated with inertial-range intermittency.
A conservative scheme of drift kinetic electrons for gyrokinetic simulation of kinetic-MHD processes in toroidal plasmas
Authors: Bao J. , Liu D. , Lin Z.
Published: October 2017

A conservative scheme of drift kinetic electrons for gyrokinetic simulations of kinetic-magnetohydrodynamic processes in toroidal plasmas has been formulated and verified. Both vector potential and electron perturbed distribution function are decomposed into adiabatic part with analytic solution and non-adiabatic part solved numerically. The adiabatic parallel electric field is solved directly from the electron adiabatic response, resulting in a high degree of accuracy. The consistency between electrostatic potential and parallel vector potential is enforced by using the electron continuity equation. Since particles are only used to calculate the non-adiabatic response, which is used to calculate the non-adiabatic vector potential through Ohm's law, the conservative scheme minimizes the electron particle noise and mitigates the cancellation problem. Linear dispersion relations of the kinetic Alfvén wave and the collisionless tearing mode in cylindrical geometry have been verified in gyrokinetic toroidal code simulations, which show that the perpendicular grid size can be larger than the electron collisionless skin depth when the mode wavelength is longer than the electron skin depth.
Versatile variable temperature and magnetic field scanning probe microscope for advanced material research
Authors: Jung Jin-Oh , Choi Seokhwan , Lee Yeonghoon , Kim Jinwoo , Son Donghyeon , Lee Jhinhwan
Published: October 2017

We have built a variable temperature scanning probe microscope (SPM) that covers 4.6 K–180 K and up to 7 T whose SPM head fits in a 52 mm bore magnet. It features a temperature-controlled sample stage thermally well isolated from the SPM body in good thermal contact with the liquid helium bath. It has a 7-sample-holder storage carousel at liquid helium temperature for systematic studies using multiple samples and field emission targets intended for spin-polarized spectroscopic-imaging scanning tunneling microscopy (STM) study on samples with various compositions and doping conditions. The system is equipped with a UHV sample preparation chamber and mounted on a two-stage vibration isolation system made of a heavy concrete block and a granite table on pneumatic vibration isolators. A quartz resonator (qPlus)-based non-contact atomic force microscope (AFM) sensor is used for simultaneous STM/AFM operation for research on samples with highly insulating properties such as strongly underdoped cuprates and strongly correlated electron systems.
X-ray microtomography system for small and light samples using a flat panel detector
Authors: Vilar A. B. , dos Santos T. M. P. , Machado A. S. , Oliveira D. F. , Azeredo S. R. , Lopes R. T.
Published: October 2017

A low-cost system able to perform microtomography of samples such as teeth, insects, or other small materials and low atomic numbers is presented. For this, a small flat panel type sensor was used. The process of characterization of the detector is detailed, as well as its main characteristics. The electromechanical control and the software used are also described. The advantages, some limitations, and comparisons with commercial systems are presented along with some three-dimensional volumetric reconstruction of different materials that served as samples during the development of the system.
Diamagnetism and neutrals depletion in a plasma
Authors: Fruchtman Amnon , Shinohara Shunjiro
Published: October 2017

Recent experimental and theoretical findings [Shinohara et al., Phys. Plasmas 23, 122108 (2016)] regarding the pressure balance between a cylindrical plasma, an axial magnetic field, and neutral gas are explored further theoretically. The length of the cylinder is assumed much larger than its radius, so that axial losses are small and cross-field transport is dominant. Conditions for either magnetic pressure or neutral pressure balancing the plasma pressure and an associated coupling parameter, which were identified in the above-mentioned recent study, are examined further. In addition, a second coupling parameter is identified which determines which is larger, the relative change in the magnetic field or the relative change in neutral density. An unexpected nonmonotonic variation of the plasma density with the plasma particle flux is demonstrated. It is shown that for plasma beta close to unity, as plasma generation and plasma particle flux increase, the plasma density surprisingly decreases. This decrease follows a decrease in plasma confinement due to an increased plasma diamagnetism. The effect of the magnetic field on neutral depletion is examined. It is shown that an increase in the magnetic field as the plasma density is kept constant results in a decrease in neutral depletion, while an increase in the magnetic field as the plasma particle flux is kept constant results in constant neutral depletion.
Tuning a 3D microwave cavity via superfluid helium at millikelvin temperatures
Authors: Souris F. , Christiani H. , Davis J. P.
Published: October 2017

Frequency tunability of three dimensional (3D) microwave cavities opens up numerous possibilities for their use in hybrid quantum systems and related technologies. For many applications, it is desirable to tune the resonance at cryogenic temperatures without mechanical actuation. We show that a superconducting 3D microwave cavity can be tuned at the percent level by taking advantage of the dielectric properties of superfluid 4He at millikelvin temperatures, without affecting its intrinsic quality factor—reaching 3 × 105 in the present experiment.
Effect of strain and thickness on the transition temperature of epitaxial FeRh thin-films
Authors: Ceballos A. , Chen Zhanghui , Schneider O. , Bordel C. , Wang Lin-Wang , Hellman F.
Published: October 2017

The separate effects of strain and film thickness on the antiferromagnetic-to-ferromagnetic phase transition temperature of FeRh thin films by both experiment and density functional calculations were determined. Strain was introduced by epitaxial growth onto MgO, SrTiO3, and KTaO3 substrates. Film thicknesses below 15 nm substantially suppress the transition temperature, T*, to below room temperature in unstrained films. For strained films, tensile/compressive strain decreases/increases T*, respectively. KTaO3 (001) substrates produce sufficient compressive strain to increase the transition temperature of 10 nm FeRh films above room temperature, which is useful for many proposed applications previously limited by the stabilization of the ferromagnetic state at small thicknesses. These results demonstrate that a judicious use of film thickness and substrate can be used to manipulate FeRh's transition temperature over a ∼200 K range.
Fast and reliable ab initio calculation of crystal field splittings in lanthanide complexes
Authors: Hallmen P. P. , Köppl C. , Rauhut G. , Stoll H. , van Slageren J.
Published: October 2017

Ab initio calculations of crystal field splittings and magnetic properties of lanthanide complexes are usually performed using state-averaged complete active space self-consistent field (CASSCF) calculations and a subsequent spin-orbit calculation mixing the CASSCF wave functions (CASSCF/state interaction with spin-orbit coupling). Because this approach becomes very time-consuming for large molecules, simplifications have been proposed in the literature to determine the state-averaged orbitals by configuration-averaged Hartree-Fock (CAHF) instead of CASSCF. We present an approach which is an extension of the CAHF method. We combine the techniques of local density fitting with CAHF and achieve a significant speedup compared to CASSCF without loss in accuracy. To assess the performance of our method, we apply it to three well-known molecules, namely, Er[N(SiMe3)2]3, Er(trensal), and the double-decker (NBu4)+ [Er(Pc)2]−.
Fokker-Planck equation for the non-Markovian Brownian motion in the presence of a magnetic field
Authors: Das Joydip , Mondal Shrabani , Bag Bidhan Chandra
Published: October 2017

In the present study, we have proposed the Fokker-Planck equation in a simple way for a Langevin equation of motion having ordinary derivative (OD), the Gaussian random force and a generalized frictional memory kernel. The equation may be associated with or without conservative force field from harmonic potential. We extend this method for a charged Brownian particle in the presence of a magnetic field. Thus, the present method is applicable for a Langevin equation of motion with OD, the Gaussian colored thermal noise and any kind of linear force field that may be conservative or not. It is also simple to apply this method for the colored Gaussian noise that is not related to the damping strength.
Direct measurement of electrocaloric effect in lead-free Ba(SnxTi1-x)O3 ceramics
Authors: Sanlialp Mehmet , Luo Zhengdong , Shvartsman Vladimir V. , Wei Xianzhu , Liu Yang , Dkhil Brahim , Lupascu Doru C.
Published: October 2017

In this study, we report on investigation of the electrocaloric (EC) effect in lead-free Ba(SnxTi1-x)O3 (BSnT) ceramics with compositions in the range of 0.08 ≤ x ≤ 0.15 by the direct measurement method using a differential scanning calorimeter. The maximum EC temperature change, ΔTEC-max = 0.63 K under an electric field of 2 kV/mm, was observed for the composition with x = 0.11 at ∼44 °C around the multiphase coexistence region. We observed that the EC effect also peaks at transitions between ferroelectric phases of different symmetries. Comparison with the results of indirect EC measurements from our previous work shows that the indirect approach provides reasonable estimations of the magnitude of the largest EC temperature changes and EC strength. However, it fails to describe correctly temperature dependences of the EC effect for the compositions showing relaxor-like behaviour (x = 0.14 and 0.15) because of their non-ergodic nature. Our study provides strong evidence supporting that looking for multiphase ferroelectric materials can be very useful to optimize EC performance.
Enhanced pair plasma generation in the relativistic transparency regime
Authors: Liu W. Y. , Luo W. , Yuan T. , Yu J. Y. , Chen M. , Sheng Z. M.
Published: October 2017

Electron-positron (e−e+) pair plasma generation in the relativistic transparency regime in a thin foil with a fixed thickness irradiated by two counter-propagating laser pulses is investigated through multi-dimensional particle-in-cell simulations. It is shown that target transparency can significantly enhance the pair generation due to the formation of a stable standing wave. An optimum foil density of 200–280 nc (with nc being the critical plasma density of the incident laser at the wavelength of 1 μm) is found for enhanced e−e+ pair generation for laser intensity around 10 PW. With such foil density, laser energy transformed to pair plasma formation is approximately four times higher than that with a foil density of 710 nc, while the laser energy transformed to γ-photons remains almost the same. Dense e−e+ plasma with a density as high as 1022 cm−3 (≃10 nc) can be produced accordingly. Comparison of pair plasma generation between cases with fundamental and double frequency driver lasers further demonstrates such an enhancement effect. It shows that when the duration of the laser pulse is relatively short, the double frequency driver can generate more pair plasmas due to the earlier excitation of relativistic transparency.
Laser induced forward transfer of graphene
Authors: Smits Edsger C. P. , Walter Arnaud , de Leeuw Dago M. , Asadi Kamal
Published: October 2017

Transfer of graphene and other two-dimensional materials is still a technical challenge. The 2D-materials are typically patterned after transfer, which leads to a major loss of material. Here, we present laser induced forward transfer of chemical vapor deposition grown graphene layers with well-defined shapes and geometries. The transfer is based on photo-decomposition of a triazene-based transfer layer that produces N2 gas, which propels a graphene layer from the donor to the acceptor substrate. The functionality of the graphene-metal junction was verified by realizing functional bottom contact bottom gate field-effect transistors.
Accelerating large-scale phase-field simulations with GPU
Authors: Shi Xiaoming , Huang Houbing , Cao Guoping , Ma Xingqiao
Published: October 2017

A new package for accelerating large-scale phase-field simulations was developed by using GPU based on the semi-implicit Fourier method. The package can solve a variety of equilibrium equations with different inhomogeneity including long-range elastic, magnetostatic, and electrostatic interactions. Through using specific algorithm in Compute Unified Device Architecture (CUDA), Fourier spectral iterative perturbation method was integrated in GPU package. The Allen-Cahn equation, Cahn-Hilliard equation, and phase-field model with long-range interaction were solved based on the algorithm running on GPU respectively to test the performance of the package. From the comparison of the calculation results between the solver executed in single CPU and the one on GPU, it was found that the speed on GPU is enormously elevated to 50 times faster. The present study therefore contributes to the acceleration of large-scale phase-field simulations and provides guidance for experiments to design large-scale functional devices.
Nanometer-scale characterization of laser-driven compression, shocks, and phase transitions, by x-ray scattering using free electron lasers
Authors: Kluge T. , Rödel C. , Rödel M. , Pelka A. , McBride E. E. , Fletcher L. B. , Harmand M. , Krygier A. , Higginbotham A. , Bussmann M. , Galtier E. , Gamboa E. , Garcia A. L. , Garten M. , Glenzer S. H. , Granados E. , Gutt C. , Lee H. J. , Nagler B. , Schumaker W. , Tavella F. , Zacharias M. , Schramm U. , Cowan T. E.
Published: October 2017

We study the feasibility of using small angle X-ray scattering (SAXS) as a new experimental diagnostic for intense laser-solid interactions. By using X-ray pulses from a hard X-ray free electron laser, we can simultaneously achieve nanometer and femtosecond resolution of laser-driven samples. This is an important new capability for the Helmholtz international beamline for extreme fields at the high energy density endstation currently built at the European X-ray free electron laser. We review the relevant SAXS theory and its application to transient processes in solid density plasmas and report on first experimental results that confirm the feasibility of the method. We present results of two test experiments where the first experiment employs ultra-short laser pulses for studying relativistic laser plasma interactions, and the second one focuses on shock compression studies with a nanosecond laser system.
Chimera states in multi-strain epidemic models with temporary immunity
Authors: Bauer Larissa , Bassett Jason , Hövel Philipp , Kyrychko Yuliya N. , Blyuss Konstantin B.
Published: October 2017

We investigate a time-delayed epidemic model for multi-strain diseases with temporary immunity. In the absence of cross-immunity between strains, dynamics of each individual strain exhibit emergence and annihilation of limit cycles due to a Hopf bifurcation of the endemic equilibrium, and a saddle-node bifurcation of limit cycles depending on the time delay associated with duration of temporary immunity. Effects of all-to-all and non-local coupling topologies are systematically investigated by means of numerical simulations, and they suggest that cross-immunity is able to induce a diverse range of complex dynamical behaviors and synchronization patterns, including discrete traveling waves, solitary states, and amplitude chimeras. Interestingly, chimera states are observed for narrower cross-immunity kernels, which can have profound implications for understanding the dynamics of multi-strain diseases.
Synergistic malaria vaccine combinations identified by systematic antigen screening
Authors: Bustamante Leyla Y. , Powell Gareth T. , Lin Yen-Chun , Macklin Michael D. , Cross Nadia , Kemp Alison , Cawkill Paula , Sanderson Theo , Crosnier Cecile , Muller-Sienerth Nicole , Doumbo Ogobara K. , Traore Boubacar , Crompton Peter D. , Cicuta Pietro , Tran Tuan M. , Wright Gavin J. , Rayner Julian C.
Published: October 2017

Significance

Malaria still kills hundreds of thousands of children each year. Malaria vaccine development is complicated by high levels of parasite genetic diversity, which makes single target vaccines vulnerable to the development of variant-specific immunity. To overcome this hurdle, we systematically screened a panel of 29 blood-stage antigens from the most deadly human malaria parasite,
Plasmodium falciparum
. We identified several targets that were able to inhibit erythrocyte invasion in two genetically diverse strains. Testing these targets in combination identified several pairs that blocked invasion more effectively in combination than in isolation. Video microscopy and studies of natural immune responses to malaria in patients suggest that targeting multiple steps in invasion is more likely to produce a synergistic vaccine response.
Impact of climate change on New York City’s coastal flood hazard: Increasing flood heights from the preindustrial to 2300 CE
Authors: Garner Andra J. , Mann Michael E. , Emanuel Kerry A. , Kopp Robert E. , Lin Ning , Alley Richard B. , Horton Benjamin P. , DeConto Robert M. , Donnelly Jeffrey P. , Pollard David
Published: October 2017

Significance

We combine downscaled tropical cyclones, storm-surge models, and probabilistic sea-level rise projections to assess flood hazard associated with changing storm characteristics and sea-level rise in New York City from the preindustrial era to 2300. Compensation between increased storm intensity and offshore shifts in storm tracks causes minimal change in modeled storm-surge heights through 2300. However, projected sea-level rise leads to large increases in future overall flood heights associated with tropical cyclones in New York City. Consequently, flood height return periods that were ∼500 y during the preindustrial era have fallen to ∼25 y at present and are projected to fall to ∼5 y within the next three decades.
PIP2 mediates functional coupling and pharmacology of neuronal KCNQ channels
Authors: Kim Robin Y. , Pless Stephan A. , Kurata Harley T.
Published: October 2017

Significance

Despite the availability of many drugs to treat epilepsy, nearly one-third of patients are not responsive to pharmacotherapy. Retigabine (RTG) is the first approved antiepileptic drug that acts by promoting activation of potassium channels, specifically targeting neuronal KCNQ channels that are regulated by both voltage and the membrane phospholipid PIP2. A deeper understanding of the mechanism of action of RTG will enable future development of this unique drug class. In this study, we combine electrophysiology recordings with fluorometric measurements of KCNQ channel conformation to reveal channel features that contribute to the dramatic effects of RTG. Our findings demonstrate that a PIP2-dependent interaction between the pore-forming and voltage-sensing components of the channel is required for optimal RTG action.
Extensive gene tree discordance and hemiplasy shaped the genomes of North American columnar cacti
Authors: Copetti Dario , Búrquez Alberto , Bustamante Enriquena , Charboneau Joseph L. M. , Childs Kevin L. , Eguiarte Luis E. , Lee Seunghee , Liu Tiffany L. , McMahon Michelle M. , Whiteman Noah K. , Wing Rod A. , Wojciechowski Martin F. , Sanderson Michael J.
Published: October 2017

Significance

Convergent and parallel evolution (homoplasy) is widespread in the tree of life and can obscure evidence about phylogenetic relationships. Homoplasy can be elevated in genomes because individual loci may have independent evolutionary histories different from the species history. We sequenced the genomes of five cacti, including the iconic saguaro of the Sonoran Desert and three other columnar cacti, to investigate whether previously uncharacterized features of genome evolution might explain long-standing challenges to understanding cactus phylogeny. We found that 60% of the amino acid sites in proteins exhibiting homoplasy do so because of conflicts between gene genealogies and species histories. This phenomenon, termed hemiplasy, is likely a consequence of the unusually long generation time of these cacti.
Finding water scarcity amid abundance using human–natural system models
Authors: Jaeger William K. , Amos Adell , Bigelow Daniel P. , Chang Heejun , Conklin David R. , Haggerty Roy , Langpap Christian , Moore Kathleen , Mote Philip W. , Nolin Anne W. , Plantinga Andrew J. , Schwartz Cynthia L. , Tullos Desiree , Turner David P.
Published: October 2017

Significance

Climate change will heighten the need to anticipate water shortages worldwide. The task is daunting due to water’s variability, spatial-temporal movement, feedbacks, and other system complexities. A high-resolution coupled human–natural system model identifies how both climate change and socioeconomic drivers will alter water scarcity in future decades. The results illuminate how water scarcity varies greatly across small distances and brief time periods, even in basins where water may be relatively abundant overall. These findings, and other unexpected results that may seem counterintuitive, underscore the potential value of such models for policy.
One- to four-year-olds connect diverse positive emotional vocalizations to their probable causes
Authors: Wu Yang , Muentener Paul , Schulz Laura E.
Published: October 2017

Significance

We find that very young children make fine-grained distinctions among positive emotional expressions and connect diverse emotional vocalizations to their probable eliciting causes. Moreover, when infants see emotional reactions that are improbable, given observed causes, they actively search for hidden causes. The results suggest that early emotion understanding is not limited to discriminating a few basic emotions or contrasts across valence; rather, young children’s understanding of others’ emotional reactions is nuanced and causal. The findings have implications for research on the neural and cognitive bases of emotion reasoning, as well as investigations of early social relationships.
Rat embryonic stem cells produce fertile offspring through tetraploid complementation
Authors: Li Tian-Da , Feng Gui-Hai , Li Yu-Fei , Wang Mei , Mao Jun-Jie , Wang Jia-Qiang , Li Xin , Wang Xue-Peng , Qu Bin , Wang Le-Yun , Zhang Xin-Xin , Wan Hai-Feng , Cui Tong-Tong , Wan Cong , Liu Lei , Zhao Xiao-Yang , Hu Bao-Yang , Li Wei , Zhou Qi
Published: October 2017

Significance

Tetraploid complementation, through which an entire organism is produced from pluripotent donor cells, is taken as the most stringent test for pluripotency. However, it remains unclear whether embryonic stem cells (ESCs) of other species besides mice can pass this test. Our results demonstrated the capacity of rat ESCs to produce live rats via tetraploid complementation and how the capacity is lost during in vitro culture. This report demonstrates that ESCs of other species besides mice can pass the tetraploid complementation test for pluripotency. We believe this original work will facilitate the understanding of evolution and regulation of pluripotency across mammalian species.
Evolutionary cascades induced by large frugivores
Authors: Brodie Jedediah F.
Published: October 2017

Significance

How eating animals affect the evolution of fruit-producing plants is still poorly understood. This is important because large vertebrates are being overhunted in ecosystems around the world, which might force plants to alter phenotypes in response to the loss of these animals. I used a natural experiment in which many of the same plant lineages in a large and megadiverse tropical archipelago have been exposed to very different suites of vertebrates on different islands. Statistical analysis that accounts for species’ shared evolutionary histories revealed that average fruit sizes across more than 400 plant species were positively related to the diversity and size of the fruit-eating birds and mammals in each area. Fruit color, however, was not affected by the vertebrate assemblage.
Alk and Ltk ligands are essential for iridophore development in zebrafish mediated by the receptor tyrosine kinase Ltk
Authors: Mo Elizabeth S. , Cheng Qianni , Reshetnyak Andrey V. , Schlessinger Joseph , Nicoli Stefania
Published: October 2017

Significance

Receptor tyrosine kinases (RTKs) and their stimulatory ligands regulate a variety of cellular processes. Many diseases, including cancer, are driven by mutations in or dysregulation of RTKs and their signaling pathways. The physiological ligands responsible for activating the RTKs, ALK and LTK, remained elusive. Recently, the ligands of each were identified and named “ALKAL1” and “ALKAL2” (“FAM150” or “augmentors”). Here, we demonstrate that zebrafish contain three distinct ligand molecules and describe their role in controlling pigment development in the embryo and adult zebrafish eye and body. These experiments show that these hormone-like molecules are critical factors influencing neural crest cell differentiation and progenitor/stem cell fates in zebrafish, suggesting a role for augmentors in control of similar processes in higher organisms.