bluuebunny/crossref_metadata_2025 huggingface dataset:
Set-free Markov state model building
Authors: Weber Marcus , Fackeldey Konstantin , Schütte Christof
Published: March 2017

Molecular dynamics (MD) simulations face challenging problems since the time scales of interest often are much longer than what is possible to simulate; and even if sufficiently long simulations are possible the complex nature of the resulting simulation data makes interpretation difficult. Markov State Models (MSMs) help to overcome these problems by making experimentally relevant time scales accessible via coarse grained representations that also allow for convenient interpretation. However, standard set-based MSMs exhibit some caveats limiting their approximation quality and statistical significance. One of the main caveats results from the fact that typical MD trajectories repeatedly re-cross the boundary between the sets used to build the MSM which causes statistical bias in estimating the transition probabilities between these sets. In this article, we present a set-free approach to MSM building utilizing smooth overlapping ansatz functions instead of sets and an adaptive refinement approach. This kind of meshless discretization helps to overcome the recrossing problem and yields an adaptive refinement procedure that allows us to improve the quality of the model while exploring state space and inserting new ansatz functions into the MSM.
Surface-effect enhanced magneto-electric coupling in FePt/PMN-PT multiferroic heterostructures
Authors: Yang Y. T. , Li J. , Peng X. L. , Hong B. , Wang X. Q. , Ge H. L. , Wang D. H. , Du Y. W.
Published: March 2017

A series of FePt films with different film thickness are deposited on Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) substrates. A standard symmetric ‘Butterfly’ shaped ΔM/M-Edc loops is obtained in 8 nm FePt/PMN-PT heterostrucuture via strain mediated magnetoelectric coupling. For the 3 nm FePt/PMN-PT heterostructure, the loop-like in-plane magnetization (M) -E curve shares a similar shape with the electric polarization of PMN-PT as a function of electric field. The value of MS shows a dramatic change of 30.9% with Edc changing from 0 to 8 kV/cm, this giant magnetoelectric effect in 3 nm FePt/PMN-PT heterostructure results from the remnant polarization induced charge on FePt/PMN-PT interface via the screening charge effect. The enhanced magnetoelectric coupling in thin magnetic/ferroelectric heterostructures opens a promising avenue for the design of ultralow power magnetoelectric devices and information storage devices.
Effect of disorder on the resistivity of CoFeCrAl films
Authors: Jin Y. , Skomski R. , Kharel P. , Valloppilly S. R. , Sellmyer D. J.
Published: March 2017

Structural and electron-transport properties of thin films of the ferrimagnetic Heusler compound CoFeCrAl have been investigated to elucidate structure-property relationships. The alloy is, ideally, a spin-gapless semiconductor, but structural disorder destroys the spin-gapless character and drastically alters the transport behavior. Two types of CoFeCrAl films were grown by magnetron sputtering deposition at 973 K, namely polycrystalline films on Si substrates and epitaxial films on MgO (001) substrates. The resistivity decreases with increasing temperature, with relatively small temperature coefficients of –0.19 μΩcm/K for the polycrystalline films and –0.12 μΩcm/K for the epitaxial films. The residual resistivity of the polycrystalline films deposited on Si is higher than that of the epitaxial film deposited on MgO, indicating that the polycrystalline films behave as so-called dirty metals.
Using collisions of AGN outflows with ICM shocks as dynamical probes
Authors: Jones T. W. , Nolting Chris , O'Neill B. J. , Mendygral P. J.
Published: March 2017

In this paper, we lay out a simple set of relationships connecting the dynamics of fast plasma jets to the dynamical state of their ambient media. The objective is to provide a tool kit that can be used to connect the morphologies of radio active galactic nuclei (AGNs) in galaxy clusters to the dynamical state of the local intracluster medium (ICM). The formalism is intended to apply to either relativistic or non-relativistic jets. Special attention is paid to interactions involving ICM shocks, although the results can be applied more broadly. Our formalism emphasizes the importance of the relative Mach number of the impacting ICM flow and the internal Mach number of the AGN jet in determining how the AGN outflows evolve.
Numerical modeling of laser-driven experiments aiming to demonstrate magnetic field amplification via turbulent dynamo
Authors: Tzeferacos P. , Rigby A. , Bott A. , Bell A. R. , Bingham R. , Casner A. , Cattaneo F. , Churazov E. M. , Emig J. , Flocke N. , Fiuza F. , Forest C. B. , Foster J. , Graziani C. , Katz J. , Koenig M. , Li C.-K. , Meinecke J. , Petrasso R. , Park H.-S. , Remington B. A. , Ross J. S. , Ryu D. , Ryutov D. , Weide K. , White T. G. , Reville B. , Miniati F. , Schekochihin A. A. , Froula D. H. , Gregori G. , Lamb D. Q.
Published: March 2017

The universe is permeated by magnetic fields, with strengths ranging from a femtogauss in the voids between the filaments of galaxy clusters to several teragauss in black holes and neutron stars. The standard model behind cosmological magnetic fields is the nonlinear amplification of seed fields via turbulent dynamo to the values observed. We have conceived experiments that aim to demonstrate and study the turbulent dynamo mechanism in the laboratory. Here, we describe the design of these experiments through simulation campaigns using FLASH, a highly capable radiation magnetohydrodynamics code that we have developed, and large-scale three-dimensional simulations on the Mira supercomputer at the Argonne National Laboratory. The simulation results indicate that the experimental platform may be capable of reaching a turbulent plasma state and determining the dynamo amplification. We validate and compare our numerical results with a small subset of experimental data using synthetic diagnostics.
Cleaning of magnetic nanoparticle surfaces via cold plasmas treatments
Authors: Poudyal Narayan , Han Guangbing , Qiu Zhaoguo , Elkins Kevin , Mohapatra Jeotikanta , Gandha Kinjal , Timmons Richard B. , Liu J. Ping
Published: March 2017

We report surface cleaning of magnetic nanoparticles (SmCo5 nanochips and CoFe2O4 nanoparticles) by using cold plasma. SmCo5 nanochips and CoFe2O4 nanoparticles, coated with surfactants (oleic acid and oleylamine, respectively) on their surfaces, were treated in cold plasmas generated in argon, hydrogen or oxygen atmospheres. The plasmas were generated using a capacitively coupled pulsed radio frequency discharge. Surface cleaning of nanoparticles was monitored by measurement of the reduction of surface carbon content as functions of plasma processing parameters and treatment times. EDX and XPS analyses of the nanoparticles, obtained after the plasma treatment, revealed significant reduction of carbon content was achieved via plasma treatment. The SmCo5 nanochips and CoFe2O4 nanoparticles treated in an argon plasma revealed reduction of atomic carbon content by more than 54 and 40 in atomic percentage, compared with the untreated nanoparticles while the morphology, crystal structures and magnetic properties are retained upon the treatments.
Effect of in-plane tensile strain in (100)/(001)-oriented epitaxial PbTiO3 films on their phase transition temperature and tetragonal distortion
Authors: Nakashima Takaaki , Ichinose Daichi , Ehara Yoshitaka , Shimizu Takao , Kobayashi Takeshi , Yamada Tomoaki , Funakubo Hiroshi
Published: March 2017

(100)/(001)-oriented epitaxial lead titanate (PbTiO3) films with various thicknesses were grown on (100) KTaO3 substrates by pulsed metal–organic chemical vapor deposition. The change of crystal structure with film thickness and deposition temperature was investigated. The paraelectric phase of 50 and 1000 nm-thick films had a tensile strain of 0.5% and almost 0% at 700 °C, respectively. The phase change temperature from the paraelectric phase to the ferroelectric phase, the Curie temperature (Tc), increased with the in-plane strain of the paraelectric phase; that is, Tc increased with decreasing film thickness. In contrast, room-temperature tetragonal distortion decreased as the film became thinner. This study reveals the effect of in-plane tensile strain in (100)/(001)-oriented epitaxial PbTiO3 films with higher Tc and smaller tetragonal distortion at room temperature.
Polarization-dependent photovoltaic effect in ferroelectric-semiconductor system
Authors: Eskandari Rahmatollah , Zhang Xiaodong , Malkinski Leszek M.
Published: March 2017

Radio-frequency (RF) magnetron sputtering method was used to fabricate ferroelectric films of hafnium oxide doped with 6 mol. % silicon. The effect of polarization of the Si doped HfO2 layer on photovoltaic properties of this ferroelectric-semiconductor system was investigated. Piezoresponse force microscopy method provided clear evidence for ferroelectric properties of HfO2 films with 10 nm thickness. Kelvin probe force microscopy showed that change in the surface potential of the negatively poled sample due to illumination is opposite to the response from unpoled and positively poled samples. Transport measurements also revealed a significant difference between photo-responses of the ferroelectric films that were polarized in opposite directions.
Volume-of-fluid simulations in microfluidic T-junction devices: Influence of viscosity ratio on droplet size
Authors: Nekouei Mehdi , Vanapalli Siva A.
Published: March 2017

We used volume-of-fluid (VOF) method to perform three-dimensional numerical simulations of droplet formation of Newtonian fluids in microfluidic T-junction devices. To evaluate the performance of the VOF method we examined the regimes of drop formation and determined droplet size as a function of system parameters. Comparison of the simulation results with four sets of experimental data from the literature showed good agreement, validating the VOF method. Motivated by the lack of adequate studies investigating the influence of viscosity ratio (λ) on the generated droplet size, we mapped the dependence of drop volume on capillary number (0.001 < Ca < 0.5) and viscosity ratio (0.01 < λ < 15). We find that for all viscosity ratios investigated, the droplet size decreases with increase in the capillary number. However, the reduction in the droplet size with the capillary number is stronger for λ < 1 than for λ > 1. In addition, we find that at a given capillary number, the size of droplets does not vary appreciably when λ < 1, while it increases when λ > 1. We develop an analytical model for predicting the droplet size that includes a viscosity-dependent breakup time for the dispersed phase. This improved model successfully predicts the effects of the viscosity ratio observed in simulations. Results from this study are useful for the design of lab-on-chip technologies and manufacture of microfluidic emulsions, where there is a need to know how system parameters influence the droplet size.
Defect mechanisms of coloration in Fe-doped SrTiO3 from first principles
Authors: Baker Jonathon N. , Bowes Preston C. , Long Daniel M. , Moballegh Ali , Harris Joshua S. , Dickey Elizabeth C. , Irving Douglas L.
Published: March 2017

To understand the underlying defect mechanisms governing the coloration of Fe-doped SrTiO3 (Fe:STO), density functional theory calculations were used to determine defect formation energies and to interpret optical absorption spectra. A grand canonical defect equilibrium model was developed using the calculated formation energies, which enabled connection to annealing experiments. It was found that FeTi0 is stable in oxidizing conditions and leads to the optical absorption signatures in oxidized Fe:STO, consistent with experiment. Fe:STO was found to transition from brown to transparent as PO2 was reduced during annealing. The defect equilibrium model reproduces a consistent PO2 of this coloration transition. Most critical to reproducing the PO2 of the coloration transition was inclusion of a FeTi-VO first nearest neighbor complex, which was found to be strongly interacting. The coloration transition PO2 was found to be insensitive to the presence of minority background impurities, slightly sensitive to Fe content, and more sensitive to annealing temperature.
Quantum confinement effect in 6H-SiC quantum dots observed via plasmon–exciton coupling-induced defect-luminescence quenching
Authors: Guo Xiaoxiao , Zhang Yumeng , Fan Baolu , Fan Jiyang
Published: March 2017

The quantum confinement effect is one of the crucial physical effects that discriminate a quantum material from its bulk material. It remains a mystery why the 6H-SiC quantum dots (QDs) do not exhibit an obvious quantum confinement effect. We study the photoluminescence of the coupled colloidal system of SiC QDs and Ag nanoparticles. The experimental result in conjunction with the theoretical calculation reveals that there is strong coupling between the localized electron-hole pair in the SiC QD and the localized surface plasmon in the Ag nanoparticle. It results in resonance energy transfer between them and resultant quenching of the blue surface-defect luminescence of the SiC QDs, leading to uncovering of a hidden near-UV emission band. This study shows that this emission band originates from the interband transition of the 6H-SiC QDs and it exhibits a remarkable quantum confinement effect.
Fully printed flexible carbon nanotube photodetectors
Authors: Zhang Suoming , Cai Le , Wang Tongyu , Miao Jinshui , Sepúlveda Nelson , Wang Chuan
Published: March 2017

Here, we report fully printed flexible photodetectors based on single-wall carbon nanotubes and the study of their electrical characteristics under laser illumination. Due to the photothermal effect and the use of high purity semiconducting carbon nanotubes, the devices exhibit gate-voltage-dependent photoresponse with the positive photocurrent or semiconductor-like behavior (conductivity increases at elevated temperatures) under positive gate biases and the negative photocurrent or metal-like behavior (conductivity decreases at elevated temperatures) under negative gate biases. Mechanism for such photoresponse is attributed to the different temperature dependencies of carrier concentration and carrier mobility, which are two competing factors that ultimately determine the photothermal effect-based photoresponse. The photodetectors built on the polyimide substrate also exhibit superior mechanical compliance and stable photoresponse after thousands of bending cycles down to a curvature radius as small as 3 mm. Furthermore, due to the low thermal conductivity of the plastic substrate, the devices show up to 6.5 fold improvement in responsivity compared to the devices built on the silicon substrate. The results presented here provide a viable path to low cost and high performance flexible photodetectors fabricated entirely by the printing process.
On the role of the entorhinal cortex in the effective connectivity of the hippocampal formation
Authors: López-Madrona Víctor J. , Matias Fernanda S. , Pereda Ernesto , Canals Santiago , Mirasso Claudio R.
Published: March 2017

Inferring effective connectivity from neurophysiological data is a challenging task. In particular, only a finite (and usually small) number of sites are simultaneously recorded, while the response of one of these sites can be influenced by other sites that are not being recorded. In the hippocampal formation, for instance, the connections between areas CA1-CA3, the dentate gyrus (DG), and the entorhinal cortex (EC) are well established. However, little is known about the relations within the EC layers, which might strongly affect the resulting effective connectivity estimations. In this work, we build excitatory/inhibitory neuronal populations representing the four areas CA1, CA3, the DG, and the EC and fix their connectivities. We model the EC by three layers (LII, LIII, and LV) and assume any possible connection between them. Our results, based on Granger Causality (GC) and Partial Transfer Entropy (PTE) measurements, reveal that the estimation of effective connectivity in the hippocampus strongly depends on the connectivities between EC layers. Moreover, we find, for certain EC configurations, very different results when comparing GC and PTE measurements. We further demonstrate that causal links can be robustly inferred regardless of the excitatory or inhibitory nature of the connection, adding complexity to their interpretation. Overall, our work highlights the importance of a careful analysis of the connectivity methods to prevent unrealistic conclusions when only partial information about the experimental system is available, as usually happens in brain networks. Our results suggest that the combination of causality measures with neuronal modeling based on precise neuroanatomical tracing may provide a powerful framework to disambiguate causal interactions in the brain.
Driven similarity renormalization group: Third-order multireference perturbation theory
Authors: Li Chenyang , Evangelista Francesco A.
Published: March 2017

A third-order multireference perturbation theory based on the driven similarity renormalization group (DSRG-MRPT3) approach is presented. The DSRG-MRPT3 method has several appealing features: (a) it is intruder free, (b) it is size consistent, (c) it leads to a non-iterative algorithm with O(N6) scaling, and (d) it includes reference relaxation effects. The DSRG-MRPT3 scheme is benchmarked on the potential energy curves of F2, H2O2, C2H6, and N2 along the F–F, O–O, C–C, and N–N bond dissociation coordinates, respectively. The nonparallelism errors of DSRG-MRPT3 are consistent with those of complete active space third-order perturbation theory and multireference configuration interaction with singles and doubles and show significant improvements over those obtained from DSRG second-order multireference perturbation theory. Our efficient implementation of the DSRG-MRPT3 based on factorized electron repulsion integrals enables studies of medium-sized open-shell organic compounds. This point is demonstrated with computations of the singlet-triplet splitting (ΔST=ET−ES) of 9,10-anthracyne. At the DSRG-MRPT3 level of theory, our best estimate of the adiabatic ΔST is 3.9 kcal mol−1, a value that is within 0.1 kcal mol−1 from multireference coupled cluster results.
Chiral magnetoresistance in Pt/Co/Pt zigzag wires
Authors: Yin Yuxiang , Han Dong-Soo , Kim June-Seo , Lavrijsen Reinoud , Lee Kyung-Jin , Lee Seo-Won , Kim Kyoung-Whan , Lee Hyun-Woo , Swagten Henk J. M. , Koopmans Bert
Published: March 2017

The Rashba effect leads to a chiral precession of the spins of moving electrons, while the Dzyaloshinskii-Moriya interaction (DMI) generates preference towards a chiral profile of local spins. We predict that the exchange interaction between these two spin systems results in a “chiral” magnetoresistance depending on the chirality of the local spin texture. We observe this magnetoresistance by measuring the domain wall (DW) resistance in a uniquely designed Pt/Co/Pt zigzag wire and by changing the chirality of the DW with applying an in-plane magnetic field. A chirality-dependent DW resistance is found, and a quantitative analysis shows a good agreement with a theory based on the Rashba model. Moreover, the DW resistance measurement allows us to independently determine the strength of the Rashba effect and the DMI simultaneously, and the result implies a possible correlation between the Rashba effect, the DMI, and the symmetric Heisenberg exchange.
Jumping-droplet electronics hot-spot cooling
Authors: Oh Junho , Birbarah Patrick , Foulkes Thomas , Yin Sabrina L. , Rentauskas Michelle , Neely Jason , Pilawa-Podgurski Robert C. N. , Miljkovic Nenad
Published: March 2017

Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22–25 °C air temperature, 20%–45% relative humidity) to determine the effect of gap spacing (2–4 mm), electric field (50–250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.
Annealing shallow Si/SiO2 interface traps in electron-beam irradiated high-mobility metal-oxide-silicon transistors
Authors: Kim J.-S. , Tyryshkin A. M. , Lyon S. A.
Published: March 2017

Electron-beam (e-beam) lithography is commonly used in fabricating metal-oxide-silicon (MOS) quantum devices but creates defects at the Si/SiO2 interface. Here, we show that a forming gas anneal is effective at removing shallow defects (≤4 meV below the conduction band edge) created by an e-beam exposure by measuring the density of shallow electron traps in two sets of high-mobility MOS field-effect transistors. One set was irradiated with an electron-beam (10 keV, 40 μC/cm2) and was subsequently annealed in forming gas while the other set remained unexposed. Low temperature (335 mK) transport measurements indicate that the forming gas anneal recovers the e-beam exposed sample's peak mobility (14 000 cm2/Vs) to within a factor of two of the unexposed sample's mobility (23 000 cm2/Vs). Using electron spin resonance (ESR) to measure the density of shallow traps, we find that the two sets of devices are nearly identical, indicating the forming gas anneal is sufficient to anneal out shallow defects generated by the e-beam exposure. Fitting the two sets of devices' transport data to a percolation transition model, we extract a T = 0 percolation threshold density in quantitative agreement with our lowest temperature ESR-measured trap densities.
Reducing conduction losses in high energy density polymer using nanocomposites
Authors: Thakur Yash , Lean Meng H. , Zhang Q. M.
Published: March 2017

For energy storage applications, it is critical that the dielectric material possesses low losses, especially the conduction losses, which could become significant at high temperatures and high electric fields. We investigate the conduction at fields up to 100 MV/m and high temperatures in a semi-crystalline poly(tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride) terpolymer which has been shown to be attractive for high energy density capacitors. Experimental results show that the insulating nanofillers are very effective in reducing the conduction current, i.e., a more than two orders of magnitude reduction in conduction can be achieved with less than 1 wt. % (<0.5 vol. %) of Al2O3 nanofillers. Experimental measurements are compared with multiscale simulations, which shows that the dominant conduction mechanism, i.e., carrier hopping in the polymer, is markedly reduced owing to a large decrease in the mobile carrier concentrations and increased trap depth, caused by the nanofillers.
Detecting switching and intermittent causalities in time series
Authors: Zanin Massimiliano , Papo David
Published: March 2017

During the last decade, complex network representations have emerged as a powerful instrument for describing the cross-talk between different brain regions both at rest and as subjects are carrying out cognitive tasks, in healthy brains and neurological pathologies. The transient nature of such cross-talk has nevertheless by and large been neglected, mainly due to the inherent limitations of some metrics, e.g., causality ones, which require a long time series in order to yield statistically significant results. Here, we present a methodology to account for intermittent causal coupling in neural activity, based on the identification of non-overlapping windows within the original time series in which the causality is strongest. The result is a less coarse-grained assessment of the time-varying properties of brain interactions, which can be used to create a high temporal resolution time-varying network. We apply the proposed methodology to the analysis of the brain activity of control subjects and alcoholic patients performing an image recognition task. Our results show that short-lived, intermittent, local-scale causality is better at discriminating both groups than global network metrics. These results highlight the importance of the transient nature of brain activity, at least under some pathological conditions.
Magnetothermoelectric effects in graphene and their dependence on scatterer concentration, magnetic field, and band gap
Authors: Kundu Arpan , Alrefae Majed A. , Fisher Timothy S.
Published: March 2017

Using a semiclassical Boltzmann transport equation approach, we derive analytical expressions for electric and thermoelectric transport coefficients of graphene in the presence and absence of a magnetic field. Scattering due to acoustic phonons, charged impurities, and vacancies is considered in the model. Seebeck (Sxx) and Nernst (N) coefficients are evaluated as functions of carrier density, temperature, scatterer concentration, magnetic field, and induced band gap, and the results are compared to experimental data. Sxx is an odd function of Fermi energy, while N is an even function, as observed in experiments. The peak values of both coefficients are found to increase with the decreasing scatterer concentration and increasing temperature. Furthermore, opening a band gap decreases N but increases Sxx. Applying a magnetic field introduces an asymmetry in the variation of Sxx with Fermi energy across the Dirac point. The formalism is more accurate and computationally efficient than the conventional Green's function approach used to model transport coefficients and can be used to explore transport properties of other materials with Dirac cones such as Weyl semimetals.
Modeling feedback control of unstable separatrix location in beam-driven field-reversed configurations
Authors: Rath N. , Onofri M. , Dettrick S. A. , Barnes D. C. , Romero J.
Published: March 2017

We present a linear, one-parameter model for rigid displacement of a toroidally symmetric plasma. When the feedback control is feasible, plasma inertia can be neglected, and the instability growth rate is proportional to wall resistivity. We benchmark the linear model against non-linear, hybrid simulations of an axially unstable, beam-driven field-reversed configuration to fix the free parameter of the model. The resulting parameter-free model is validated using linear and non-linear closed-loop simulations with active feedback control by voltage-controlled coils. In closed loop simulations, the predictions of the parameter-free linear model agree satisfactory with the non-linear results. Implications for the feedback control of the positional instability in experiments are discussed. The presented model has been used to guide the design of the feedback control hardware in the C-2W experiment.
The influence of the cathode array and the pressure variations on the current sheath dynamics of a small plasma focus device in the presence of an axial magnetic probe
Authors: Piriaei D. , Javadi S. , Mahabadi T. D. , Yousefi H. R. , Salar Elahi A. , Ghoranneviss M.
Published: March 2017

In this research, the influence of the cathode array and the pressure variations on the current sheath dynamics of a small plasma focus device (450 J) was investigated. For this purpose, the signals of an axial magnetic probe for two different gases (argon and nitrogen) were studied. The magnetic probe signals showed the slower movement of the current sheath layer when the number of cathode rods decreased. This was related to the increase in the circuit inductance, which caused the longer discharge time of the capacitor bank followed by the creation of runaway electrons. These electrons in turn produced the impurities that led to the appearance of the instabilities inside the plasma. On the other hand, in order to investigate the effect of the cathode array variation on the instabilities produced inside the plasma, the wavelet technique was used. With the aid of frequency analysis, this technique showed the increase in these instabilities, which was due to the non-uniform formation of the current sheath layer during the breakdown phase, and finally, the higher values of the pressure caused the slower movement of the current sheath due to the inverse relation of the current sheath velocity to the square root of the pressure.
Effect of a damping force on dust acoustic waves simulated by particle-in-cell method
Authors: Gao Dong-Ning , Zhang Heng , Zhang Jie , Li Zhong-Zheng , Duan Wen-shan
Published: March 2017

Damping dust acoustic waves described by the Korteweg-de Vries-type (KdV-type) equation and the nonlinear Schrödinger equation-type (quasi-NLSE) have been studied by the particle-in-cell (PIC) simulation method. The KdV-type equation and the quasi-NLSE with dust-neutral collision are analytically obtained by the reductive perturbation method. The PIC simulation methods for dust acoustic waves with damping force are shown. The PIC simulation results are compared with the analytical one. The relationship of the damping coefficient with the collision frequency is obtained. It is found that amplitudes of KdV-type solitary waves and quasienvelope solitary waves with damping force decrease exponentially.
Study on approach of performance improvement of VAWT employing double multiple stream tubes model
Authors: Zhao Zhenzhou , Yan Chang , Wang Tongguang , Xu Bofeng , Zheng Yuan
Published: March 2017

On the circular blade path of a Darrieus-type vertical axis wind turbine (VAWT), there are two azimuth positions where torques are small or even negative. These two azimuths have the lowest aerodynamic performance and greatly weaken the overall performance of the VAWT. An approach is proposed to rebuild the flow field of the turbine blades by applying two additional airflows at the two azimuths to enhance the local performance. The aim is to improve the overall power coefficient of the VAWT. A Φ-type VAWT with a diameter of 2 m and a height of 2 m is studied to evaluate the effectiveness of the proposed approach. The effect of additional airflow on the aerodynamic performance of the blade and the turbine is researched using the double multiple streamtube model. The simulation results suggest that the additional airflows are effective in promoting the performance of the rotor blades and the overall rotor; the increase in maximum power coefficient achieved was 6% at an optimum tip speed ratio. Some rules of the effect on the performances of the rotor are obtained in this paper.
Terahertz-wave differential detection based on simultaneous dual-wavelength up-conversion
Authors: Takida Yuma , Nawata Kouji , Suzuki Safumi , Asada Masahiro , Minamide Hiroaki
Published: March 2017

We report a terahertz (THz)-wave differential detection based on simultaneous dual-wavelength up-conversion in a nonlinear optical MgO:LiNbO3 crystal with optical and electronic THz-wave sources. The broadband parametric gain and noncollinear phase-matching of MgO:LiNbO3 provide efficient conversion from superposed THz waves to spatially distributed near-infrared (NIR) beams to function as a dispersive THz-wave spectrometer without any additional dispersive element. We show that the μW-level THz waves from two independent sources, a 0.78-THz injection-seeded THz-wave parametric generator (is-TPG) and a 1.14-THz resonant tunneling diode (RTD), are simultaneously up-converted to two NIR waves and then detected with two NIR photodetectors. By applying a balanced detection scheme to this dual-frequency detection, we demonstrate THz-wave differential imaging of maltose and polyethylene pellets in the transmission geometry. This dual-wavelength detection is applicable to more than three frequencies and broadband THz-wave radiation for real-time THz-wave spectroscopic detection and imaging.
Analysis of a commercial-scale photovoltaics system performance and economic feasibility
Authors: Kang Moon Hee , Kim Nari , Yun Changhun , Kim Yong Hyun , Rohatgi Ajeet , Han Sang Taek
Published: March 2017

The performance of a commercial-scale (86.4 kWp) rooftop grid-connected photovoltaic (PV) system was investigated from the measured daily power generation and weather. The PV system was installed in Atlanta, GA, USA, where global solar irradiation varies from 3.3 to 9.0 kWh/m2 day (average: 4.7 kWh/m2 day). Annual power generation measured from this PV system was 110 MWh with a capacity factor of 14.5%. This is also equivalent to a carbon reduction of 25.2 tons/yr. Furthermore, for an accurate assessment of the total system derate losses and the levelized cost of electricity (LCOE), System Advisory Model modelings were performed. From the modelling, the total PV system derate losses were calculated to be 27% (including inverter loss) and the LCOE value was 14¢/kWh. Note that the installed system cost was 4.18$/W when it was installed in 2011, assuming 30 years of lifetime and a weighted average cost of capital of 5.6%. However, in 2016, one can install PV systems only at 2.2$/W instead of 4.18$/W, so the LCOE can be down to 7¢/kWh. As the price of commercial electricity in GA is about 9.6¢/kWh, a LCOE of 7¢/kWh can match the grid parity.
Two-qubit state tomography with ensemble average in coupled superconducting qubits
Authors: Li Mengmeng , Xue Guangming , Tan Xinsheng , Liu Qiang , Dai Kunzhe , Zhang Ke , Yu Haifeng , Yu Yang
Published: March 2017

We propose a scheme to perform two-qubit state tomography by independently measuring the ensemble average of quantum states of two coupled superconducting transmon qubits. Each qubit is capacitively coupled to its own readout cavity and can be measured separately. In order to obtain the density matrix of a two-qubit state, we apply four two-qubit unitary operations to the initial state and measure the corresponding qubit states, from which the elements of the two-qubit density matrix can be extracted. By using this scheme, we measure the entangled two qubits with high fidelity.
Effect of the sheath thickness of thin inhomogeneous plasma layer on the propagation constant for the surface waves
Authors: Li Wenqiu , Wang Gang , Xiang Dong , Su Xiaobao
Published: March 2017

Based on the dispersion equation obtained from the Helmholtz equation in the plasma sheath region and main plasma column for surface waves, the propagation constant properties on the interface of the plasma sheath region and main plasma column region are studied. The analytic formula of propagation constant for the azimuthally symmetric surface wave (m = 0 mode) and non-symmetric surface waves (m = 1, 2, 3, and 4 modes) on the interface is presented, which indicates the effect of the thickness of the plasma sheath region on the propagation constant characteristics. The analytical result shows that the thickness has a significant influence on the propagation constant when the thickness is 0.01 times smaller than the thickness of the main plasma column region for both the symmetric and non-symmetric surface waves, while there is a significant difference in the propagation constant amplitude between the m = 1 mode and other four modes.
From Superman to Social Realism
Authors: Jensen Helle Strandgaard
Published: March 2017

Can children’s media be a source of education and empowerment? Or is the commercial media market a threat to their sense of social and democratic values? Such questions about the appropriateness of children’s media consumption have recurred in public debates throughout the twentieth century. From Superman to Social Realism provides an exciting new approach to the study of children’s media and childhood history, drawing on theories of cross-media consumption and transnational history. Based on extensive Scandinavian source material, it explores public debates about children’s media between 1945 and 1985. Readers are taken on a fascinating journey through debates about superheroes in the 1950s, politicization of children’s media in the 1960s, and about television and social realism in the 1980s. Arguments are firmly contextualized in Scandinavian childhood and welfare state history, an approach that demonstrates why professional and political groups have perceived children’s media as the key to the enculturation of future generations.

Received honourable mention at Nordic History Book Prize (Den nordiske historiebogpris 2017)
Context-dependency of argumentative patterns in discourse
Authors: van Eemeren Frans H.
Published: March 2017

This introductory article concludes the examination of prototypical argumentative patterns manifesting themselves in communicative activity types in the political, legal and medical domain reported in this special issue of theJournal of Argumentation in Context(JAIC) and an earlier special issue of the journalArgumentation(2016, 30(1)). First, the results pertaining to the use of pragmatic argumentation in the main argumentation of prototypical argumentative patterns in the various domains are described that were reported in the latter issue. Next, the results are described which are reported in this issue ofJAIC; they pertain to prototypical argumentative patterns in the various domains that come into being as a result of the employment of an argument scheme in the main argumentation that is perfectly suited for being used in a certain communicative activity type in a specific domain. In the following section an overview is provided of the most conspicuous differences in the prototypical argumentative patterns between the various communicative domains caused by the institutional preconditions for strategic maneuvering in the communicative activity types that were examined. Finally, some general conclusions are discussed.
New Insights into the Semantics of Legal Concepts and the Legal Dictionary
Authors: Bajcic Martina
Published: March 2017

This book focuses on legal concepts from the dual perspective of law and terminology. While legal concepts frame legal knowledge and take center stage in law, the discipline of terminology has traditionally been about concept description. Exploring topics common to both disciplines such as meaning, conceptualization and specialized knowledge transfer, the book gives a state-of-the-art account of legal interpretation, legal translation and legal lexicography with special emphasis on EU law. The special give-and-take of law and terminology is illuminated by real-life legal cases which demystify the ways courts do things with concepts. This original approach to the semantics of legal concepts is then incorporated into the making of a legal dictionary, thus filling a gap in the theory and practice of legal lexicography. With its rich repertoire of examples of legal terms in different languages, the book provides a blend of theory and practice, making it a valuable resource not only for scholars of law, language and lexicography but also for legal translators and students.
Effects of CFT Legumine (5% Rotenone) on Tadpole Survival and Metamorphosis of Chiricahua Leopard Frogs Lithobates chiricahuensis, Northern Leopard Frogs L. pipiens, and American Bullfrogs L. catesbeianus
Authors: Alvarez Guillermo , Caldwell Colleen A. , Kruse Carter G.
Published: March 2017

Amphibians may experience collateral effects if exposed to CFT Legumine (5% rotenone), a piscicide that is used to remove invasive fish. A series of 48‐h static toxicity tests assessed the acute effects of CFT Legumine on multi‐aged tadpoles of the federally listed Chiricahua leopard frog Lithobates chiricahuensis, the widespread northern leopard frog L. pipiens, and the increasingly invasive American bullfrog L. catesbeianus. At the earliest Gosner stages (GS 21–25), Chiricahua leopard frogs were more sensitive to CFT Legumine (median lethal concentration [LC50] = 0.41–0.58 mg/L) than American bullfrogs (LC50 = 0.63–0.69 mg/L) and northern leopard frogs (LC50 = 0.91 and 1.17 mg/L). As tadpoles developed (i.e., increase in GS), their sensitivity to rotenone decreased. In a separate series of 48‐h static nonrenewal toxicity tests, tadpoles (GS 21–25 and GS 31–36) of all three species were exposed to piscicidal concentrations of CFT Legumine (0.5, 1.0, and 2.0 mg/L) to assess postexposure effects on metamorphosis. In survivors of all three species at both life stages, the time to tail resorption was nearly doubled in comparison with that of controls. For example, mid‐age (GS 31–36) Chiricahua leopard frog tadpoles required 210.7 h to complete tail resorption, whereas controls required 108.5 h. However, because tail resorption is a relatively short period in metamorphosis, the total duration of development (days from posthatch to complete metamorphosis) and the final weight did not differ in either age‐group surviving nominal concentrations of 0.5‐, 1.0‐, and 2.0‐mg/L CFT Legumine relative to controls. This research demonstrates that the CFT Legumine concentrations commonly used in field applications to remove unwanted fish could result in considerable mortality of the earliest stages of Lithobates species. In addition to acute lethality, piscicide treatments may result in delayed tail resorption, which places the tadpoles at risk by increasing their vulnerability to predation and pathogens.

Received October 1, 2016; accepted January 17, 2017 Published online March 30, 2017
Atmospheric corrosion of Zn–Al coatings in a simulated automotive environment
Authors: Zhang Xian , Odnevall Wallinder Inger , Leygraf Christofer
Published: March 2017

Accelerated NVDA (VDA 233-102) tests were performed on bare Zn and Al sheets, Galfan coating (Zn–5 wt-% Al) and Galvalume coating (Zn–55 wt-% Al) on steel. ZnO, Zn(OH)2 and Zn5(OH)8Cl2·H2O were the main corrosion products identified on both bare Zn sheet and Galfan. AlOOH and Al(OH)3 were preferentially formed on bare Al sheet and Galvalume. In addition, Zn–Al–containing corrosion products, Zn6Al2(OH)16CO3·4H2O and/or Zn2Al(OH)6Cl·2H2O were identified on both Galfan and Galvalume. Corrosion products of Zn6Al2(OH)16CO3·4H2O with a platelet morphology were preferentially formed in the zinc-rich interdendritic regions of the Galvalume surface. Galfan revealed a similar corrosion behaviour as bare Zn sheet, whereas Galvalume exhibited similar behaviour as bare Al sheet. Deposition of chlorides highly influenced the corrosion of both Galvalume and Al rather than Galfan and Zn due to the rapid local damage of the compact native thin film of Al2O3.
Educational equalization stalled? Trends in inequality of educational opportunity between 1930 and 1980 across 26 European nations
Authors: Barone Carlo , Ruggera Lucia
Published: March 2017

This article assesses trends over time in the influence of social origins on educational attainment in 26 European countries. We use a cumulative dataset that merges the European Social Survey (waves 2002–2010), the International Social Survey Programme (1999, 2009) and the European Value Study (2008). Our contribution to the literature is threefold. First, we replicate as closely as possible the previous study by Breen et al. [(2009) ‘Nonpersistent in educational attainment: Evidence from eight European countries’, American Journal of Sociology 114: 1475–1521] and extend it to a larger set of countries and to more recent cohorts. Second, we reassess the argument that equalization does not involve Higher Education. Third, we consider whether our conclusions change if we use a more comprehensive measurement of social origins that jointly incorporates indicators of social class, social status and parental education. We detect a generalized reduction of educational inequalities in the post-war decades. When we focus on Higher Education, we still detect evidence of equalization, although to a lower extent. Our analyses do not support the claim that, when using a more comprehensive treatment of social origins, the patterns for different indicators evolve in opposite directions.
Myosin II promotes the anisotropic loss of the apical domain during Drosophila neuroblast ingression
Authors: Simões Sérgio , Oh Youjin , Wang Michael F.Z. , Fernandez-Gonzalez Rodrigo , Tepass Ulrich
Published: March 2017

Epithelial–mesenchymal transitions play key roles in development and cancer and entail the loss of epithelial polarity and cell adhesion. In this study, we use quantitative live imaging of ingressing neuroblasts (NBs) in Drosophila melanogaster embryos to assess apical domain loss and junctional disassembly. Ingression is independent of the Snail family of transcriptional repressors and down-regulation of Drosophila E-cadherin (DEcad) transcription. Instead, the posttranscriptionally regulated decrease in DEcad coincides with the reduction of cell contact length and depends on tension anisotropy between NBs and their neighbors. A major driver of apical constriction and junctional disassembly are periodic pulses of junctional and medial myosin II that result in progressively stronger cortical contractions during ingression. Effective contractions require the molecular coupling between myosin and junctions and apical relaxation of neighboring cells. Moreover, planar polarization of myosin leads to the loss of anterior–posterior junctions before the loss of dorsal–ventral junctions. We conclude that planar-polarized dynamic actomyosin networks drive apical constriction and the anisotropic loss of cell contacts during NB ingression.
The bacterial virulence factors VopL and VopF nucleate actin from the pointed end
Authors: Burke Thomas A. , Harker Alyssa J. , Dominguez Roberto , Kovar David R.
Published: March 2017

VopL and VopF (VopL/F) are tandem WH2-domain actin assembly factors used by infectious Vibrio species to induce actin assembly in host cells. There is disagreement about the filament assembly mechanism of VopL/F, including whether they associate with the filament barbed or pointed end. Here, we used multicolor total internal reflection fluorescence microscopy to directly observe actin assembly with fluorescently labeled VopL/F. In actin monomer assembly reactions, VopL/F exclusively nucleate actin filament assemblies, remaining only briefly associated with the pointed end. VopL/F do not associate with the ends of preassembled filaments. In assembly reactions with saturating profilin, ∼85% of VopL/F molecules also promote nucleation from the pointed end, whereas a smaller fraction (<15%) associate for ∼25 s with the barbed end of preassembled filaments, inhibiting their elongation. We conclude that VopL/F function primarily as actin nucleation factors that remain briefly (∼100 s) associated with the pointed end.