bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for drift waves in the turbulence of reversed field pinch plasmas
Authors: Thuecks D. J. , Almagri A. F. , Sarff J. S. , Terry P. W.
Published: March 2017

A detailed characterization of the high-frequency range of the fluctuation spectrum in reversed field pinch plasmas is presented, revealing a variety of new features distinct from global tearing modes and the cascade that they are thought to drive. The anisotropic broadband spectrum of the fluctuating electric field is measured. The power in the fluctuating kinetic energy (1/2)miniṼẼ×B02, previously measured to be smaller than the magnetic energy in the tearing-mode-unstable frequency range, becomes greater than and diverges from the magnetic energy above 60–80 kHz. The lack of equipartition at high frequencies coincides with the measured signatures of the independent fluctuation activity broadly consistent with the drift-wave fluctuations. Statistical coherence measurements reveal the mode activity that is compressive with a large amplitude in the vicinity of strong density gradients and with a phase speed comparable to the electron drift speed. There is a distinct high-frequency correlation between the fluctuations of density and the parallel magnetic field. Elevated coherences associated with this fluctuation feature return more quickly after a sawtooth event than the corresponding coherences associated with tearing activity.
A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals
Authors: Al-Zangana S. , Turner M. , Dierking I.
Published: March 2017

The electro-optic and dielectric properties of barium titanate, BaTiO3, and nanoparticle (NP) doped nematic and ferroelectric liquid crystal materials were examined with respect to different size and concentrations of the NPs. Smaller size paraelectric NPs (≈80 nm) are compared to larger, ferroelectric NPs (≈240 nm). It is found that for concentrations larger than 0.5 vol. %, the ferroelectric NPs exhibit an increasing effect on the electro-optic response of the nematic liquid crystal, which is demonstrated by the enhancement of the dielectric anisotropy. This could be induced by the coupling of the electrical dipole moments in the spherical NPs with the LC director field. The electro-optical properties of the SmC* phase, such as the tilt angle Θ, switching time τs, and spontaneous polarisation  Ps, are found to be independent of the concentration and size of the NPs. The rotational viscosity η calculated from response times, polarization reversal current, and dielectric properties is comparable for all three methods employed and practically independent of particle concentration and size. The relaxation frequency fR of the Goldstone mode is higher in the ferroelectric NPs suspensions of 2.0 vol. % as compared to the smaller paraelectric NPs.
Generation and evolution of magnetic field in the relativistic plasma following q-nonextensive distribution
Authors: Lin Fu-Jun , Chen Zong-Hua , Li Xiao-Qing , Liao Jing-Jing , Zhu Yun
Published: March 2017

A GigaGauss quasi-steady magnetic field can be generated in astrophysical plasmas and laser-produced plasmas with high-frequency electromagnetic radiation through wave-wave and wave-particle interactions. A set of governing equations for this field are obtained in the plasma consisting of ultra-relativistic electrons following q-nonextensive distribution. The numerical results show that the initial field is unstable and can collapse to generate various spatially intermittent magnetic flux tubes. It can also be found that the behavior of the magnetic field is greatly dependent on the nonextensive index q, which may be helpful in understanding the magnetic turbulence.
The longitudinal plasmas modes of κ-deformed Kaniadakis distributed plasmas
Authors: Chen H. , Zhang S. X. , Liu S. Q.
Published: March 2017

In the present paper, the dispersions and Landau damping of the Langmuir waves and ion sound waves in the κ-deformed Kaniadakis distributed plasma system are investigated within the plasma kinetic theory regimes. The results show that the peculiarities of the dispersions and Landau damping of both the Langmuir waves and ion sound waves depend on the parameter κ of the distribution function. For Langmuir waves, the dispersion is enhanced, while the Landau damping is suppressed by κ. On the contrary, for ion sound waves, both the dispersion and Landau damping are increased by κ. As expected, the results of the Maxwellian case are recovered perfectly when κ = 0.
Three-dimensional geometry of magnetic reconnection induced by ballooning instability in a generalized Harris sheet
Authors: Zhu Ping , Bhattacharjee Amitava , Sangari Arash , Wang Zechen , Bonofiglo Phillip
Published: March 2017

We report for the first time the intrinsically three-dimensional (3D) geometry of the magnetic reconnection process induced by ballooning instability in a generalized Harris sheet. The spatial distribution and the structure of the quasi-separatrix layers, as well as their temporal emergence and evolution, indicate that the associated magnetic reconnection can only occur in a 3D geometry, which is irreducible to that of any two-dimensional reconnection process. Such a finding provides a new perspective to the long-standing controversy over the substorm onset problem and elucidates the combined roles of reconnection and ballooning instabilities. It also connects to the universal presence of 3D reconnection processes previously discovered in various natural and laboratory plasmas.
Dressing effects on the occurrence scattering time for dust-dust collisions in a complex plasma
Authors: Lee Myoung-Jae , Jung Young-Dae
Published: March 2017

The dressing effects on the occurrence scattering time for the dust-dust interaction are investigated in a complex plasma. The first-order eikonal analysis is applied to obtain the scattering amplitude and the occurrence scattering time for the dust-dust interaction. The result shows that the dressing effect enhances the retardation phenomenon of the occurrence scattering time in the forward scattering domain. It is shown that the oscillatory behavior of the scaled occurrence scattering time is getting more significant with an increase in the Debye length. It is also found that the retardation domain of the occurrence scattering time increases with a decrease in the Debye length. The variation of the occurrence scattering time retardation and advance due to the dressing effect is also discussed.
Sparse identification of a predator-prey system from simulation data of a convection model
Authors: Dam Magnus , Brøns Morten , Juul Rasmussen Jens , Naulin Volker , Hesthaven Jan S.
Published: March 2017

The use of low-dimensional dynamical systems as reduced models for plasma dynamics is useful as solving an initial value problem requires much less computational resources than fluid simulations. We utilize a data-driven modeling approach to identify a reduced model from simulation data of a convection problem. A convection model with a pressure source centered at the inner boundary models the edge dynamics of a magnetically confined plasma. The convection problem undergoes a sequence of bifurcations as the strength of the pressure source increases. The time evolution of the energies of the pressure profile, the turbulent flow, and the zonal flow capture the fundamental dynamic behavior of the full system. By applying the sparse identification of nonlinear dynamics (SINDy) method, we identify a predator-prey type dynamical system that approximates the underlying dynamics of the three energy state variables. A bifurcation analysis of the system reveals consistency between the bifurcation structures, observed for the simulation data, and the identified underlying system.
Dielectric relaxation and Maxwell-Wagner interface polarization in Nb2O5 doped 0.65BiFeO3–0.35BaTiO3 ceramics
Authors: Wang Tong , Hu Jiacong , Yang Haibo , Jin Li , Wei Xiaoyong , Li Chunchun , Yan Fei , Lin Ying
Published: March 2017

Electrical characterizations of Nb2O5 doped 0.65BiFeO3–0.35BaTiO3 (0.65BF–0.35BT) ceramic were carried out over broad temperature and frequency ranges through dielectric spectroscopy, impedance spectroscopy, and ac conductivity measurements. The dielectric constant and loss tangent are drastically reduced with introducing Nb2O5 into the 0.65BF–0.35BT system. Two dielectric anomalies are detected in the temperature regions of 100 °C ≤ T ≤ 280 °C and 350 °C ≤ T ≤ 480 °C, and the Curie temperature (TC) was confirmed in higher temperature region. A dielectric relaxation with large dielectric constants was detected near the TC. This dielectric relaxation becomes even stronger with the gradual increase in the Nb2O5 content. Impedance spectroscopy results clearly show the contributions of grains and grain boundaries in the frequency range of 100 Hz ≤ f ≤ 1 MHz, and the relaxation processes for grains and grain boundaries are non-Debye-type. The grain boundaries are more resistive than that of the grains, revealing the inhomogeneity in samples. The experimental results are well fitted based on a Maxwell-Wagner (MW) interfacial polarization model below 100 kHz, and the MW interfacial polarization effect becomes more and more obvious with the increase in the Nb2O5 content. The increase in dielectric constant is possibly related to space charge polarization, which is caused by charges accumulated at the interface between the grain and grain boundaries. Frequency dependence of the ac conductivity confirms the MW interfacial polarization effect below 100 kHz.
Passivation mechanism in silicon heterojunction solar cells with intrinsic hydrogenated amorphous silicon oxide layers
Authors: Deligiannis Dimitrios , van Vliet Jeroen , Vasudevan Ravi , van Swaaij René A. C. M. M. , Zeman Miro
Published: March 2017

In this work, we use intrinsic hydrogenated amorphous silicon oxide layers (a-SiOx:H) with varying oxygen content (cO) but similar hydrogen content to passivate the crystalline silicon wafers. Using our deposition conditions, we obtain an effective lifetime (τeff) above 5 ms for cO ≤ 6 at. % for passivation layers with a thickness of 36 ± 2 nm. We subsequently reduce the thickness of the layers using an accurate wet etching method to ∼7 nm and deposit p- and n-type doped layers fabricating a device structure. After the deposition of the doped layers, τeff appears to be predominantly determined by the doped layers themselves and is less dependent on the cO of the a-SiOx:H layers. The results suggest that τeff is determined by the field-effect rather than by chemical passivation.
A new family of multifunctional silicon clathrates: Optoelectronic and thermoelectric applications
Authors: Liu Yinqiao , Jiang Xue , Huang Yingying , Zhou Si , Zhao Jijun
Published: March 2017

To develop Si structures for multifunctional applications, here we proposed four new low-density silicon clathrates (Si-CL-A, Si-CL-B, Si-CL-C, and Si-CL-D) based on the same bonding topologies of clathrate hydrates. The electronic and thermal properties have been revealed by first-principles calculations. By computing their equation of states, phonon dispersion, and elastic constants, the thermodynamic, dynamic, and mechanical stabilities of Si-CL-A, Si-CL-B, Si-CL-C, and Si-CL-D allotropes are confirmed. In the low-density region of the phase diagram, Si-CL-B, Si-CL-D, and Si-CL-C would overtake diamond silicon and type II clathrate (Si-CL-II) and emerge as the most stable Si allotropes successively. Among them, the two direct semiconductors with bandgaps of 1.147 eV (Si-CL-A) and 1.086 eV (Si-CL-D) are found. The suitable bandgaps close to the optimal Shockley-Queisser limit result in better absorption efficiency in solar spectrum than conventional diamond silicon. Owing to the unique cage-based framework, the thermal conductivity of these Si allotropes at room temperature are very low (2.7–5.7 Wm−1 K−1), which are lower than that of diamond structured Si by two orders of magnitude. The suitable bandgaps, small effective masses, and low thermal conductivity of our new silicon allotropes are anticipated to find applications in photovoltaic and thermoelectric devices.
Analysis of large-anisotropy-spin recoupling pulses for distance measurement under magic-angle spinning NMR shows the superiority and robustness of a phase modulated saturation pulse
Authors: Nimerovsky E. , Makrinich M. , Goldbourt A.
Published: March 2017

The distance between a spin one-half and an attached spin possessing a large anisotropy can be obtained using different dipolar recoupling sequences that are based on the rotational-echo double resonance technique under magic-angle spinning solid-state NMR. The general difference between these sequences with respect to the coupled spin is the set of pulses applied in order to drive this spin out of equilibrium, thereby recoupling the dipolar interaction. Since complete inversion is practically not possible due to the coupled-spin anisotropy, using one or another pulse depends on the experimental and spin conditions: the spinning speed, the strength of the radio frequency field, the size of the anisotropic interaction (quadrupolar or chemical shift anisotropy couplings), the offset, and the accuracy of setting the magic angle. Here we present a detailed description of the behavior of the anisotropic spin magnetization, including the macroscopic level transition probabilities, the degree of inversion, and the microscopic and macroscopic magnetizations during the applications of these pulses under different experimental conditions. As simulations show, a complete randomization of spin populations under a wide range of experimental conditions occurs under a specific phase modulation of the recoupling pulse while for all other cases dependence on experimental conditions is large and the achievable bandwidth is limited. A result of this detailed analysis is that the extension of the phase modulated pulse extends even further its robustness. The saturation capability is demonstrated experimentally for the quadrupolar spin of boron-11 in 4-methoxyphenylboronic acid.
Rotationally inelastic collisions of H2+ ions with He buffer gas: Computing cross sections and rates
Authors: Hernández Vera Mario , Gianturco F. A. , Wester R. , da Silva H. , Dulieu O. , Schiller S.
Published: March 2017

We present quantum calculations for the inelastic collisions between H2+ molecules, in rotationally excited internal states, and He atoms. This work is motivated by the possibility of experiments in which the molecular ions are stored and translationally cooled in an ion trap and a He buffer gas is added for deactivation of the internal rotational population, in particular at low (cryogenic) translational temperatures. We carry out an accurate representation of the forces at play from an ab initio description of the relevant potential energy surface, with the molecular ion in its ground vibrational state, and obtain the cross sections for state-changing rotationally inelastic collisions by solving the coupled channel quantum scattering equations. The presence of hyperfine and fine structure effects in both ortho- and para-H2+ molecules is investigated and compared to the results where such a contribution is disregarded. An analysis of possible propensity rules that may predict the relative probabilities of inelastic events involving rotational state-changing is also carried out, together with the corresponding elastic cross sections from several initial rotational states. Temperature-dependent rotationally inelastic rates are then computed and discussed in terms of relative state-changing collisional efficiency under trap conditions. The results provide the essential input data for modeling different aspects of the experimental setups which can finally produce internally cold molecular ions interacting with a buffer gas.
A heterodyne straightness and displacement measuring interferometer with laser beam drift compensation for long-travel linear stage metrology
Authors: Chen Benyong , Cheng Liang , Yan Liping , Zhang Enzheng , Lou Yingtian
Published: March 2017

The laser beam drift seriously influences the accuracy of straightness or displacement measurement in laser interferometers, especially for the long travel measurement. To solve this problem, a heterodyne straightness and displacement measuring interferometer with laser beam drift compensation is proposed. In this interferometer, the simultaneous measurement of straightness error and displacement is realized by using heterodyne interferometry, and the laser beam drift is determined to compensate the measurement results of straightness error and displacement in real time. The optical configuration of the interferometer is designed. The principle of the simultaneous measurement of straightness, displacement, and laser beam drift is depicted and analyzed in detail. And the compensation of the laser beam drift for the straightness error and displacement is presented. Several experiments were performed to verify the feasibility of the interferometer and the effectiveness of the laser beam drift compensation. The experiments of laser beam stability show that the position stability of the laser beam spot can be improved by more than 50% after compensation. The measurement and compensation experiments of straightness error and displacement by testing a linear stage at different distances show that the straightness and displacement obtained from the interferometer are in agreement with those obtained from a compared interferometer and the measured stage. These demonstrate that the merits of this interferometer are not only eliminating the influence of laser beam drift on the measurement accuracy but also having the abilities of simultaneous measurement of straightness error and displacement as well as being suitable for long-travel linear stage metrology.
Electrostatic interactions in dissipative particle dynamics—Ewald-like formalism, error analysis, and pressure computation
Authors: Vaiwala Rakesh , Jadhav Sameer , Thaokar Rochish
Published: March 2017

An accurate time evolution of charged species having exponentially smeared out charge density (Slater type charge distribution) in dissipative particle dynamic (DPD) simulations necessitates the optimal choice of the Ewald splitting parameter (α), charge smearing length (λ), and real space cutoff (c) when the Ewald summation or its variant such as particle-particle particle-mesh or particle-mesh Ewald is employed for long range electrostatics. The present article offers the error estimates in the electrostatic energy and the force as a function of α and β (1/λ) on account of spherical truncation c in real space. These error estimate formulae are validated by our DPD simulation results. We also give here an Ewald-like derivation for electrostatic energy and force for the Slater type charge density. A quick estimate of the electrostatic pressure without the use of the tedious expression which involves three dimensional Fourier transforms is also presented, and its range of validity is discussed. The basis for the proposed formula for pressure is the fact that the minimum-image truncation in many cases allows one to compute the thermodynamic quantities with reasonable accuracy.
Time-delay and reality conditions for complex solitons
Authors: Cen Julia , Correa Francisco , Fring Andreas
Published: March 2017

We compute lateral displacements and time-delays for scattering processes of complex multi-soliton solutions of the Korteweg de-Vries equation. The resulting expressions are employed to explain the precise distinction between solutions obtained from different techniques, Hirota’s direct method and a superposition principle based on Bäcklund transformations. Moreover they explain the internal structures of degenerate compound multi-solitons previously constructed. Their individual one-soliton constituents are time-delayed when scattered amongst each other. We present generic formulae for these time-dependent displacements. By recalling Gardner’s transformation method for conserved charges, we argue that the structure of the asymptotic behaviour resulting from the integrability of the model together with its PT-symmetry ensures the reality of all of these charges, including in particular the mass, the momentum, and the energy.
Stimulated backward Raman scattering driven collectively by two picosecond laser pulses in a bi- or multi-speckle configuration
Authors: Glize K. , Rousseaux C. , Bénisti D. , Dervieux V. , Gremillet L. , Baton S. D. , Lancia L.
Published: March 2017

In this paper, we investigate, both experimentally and numerically, the backward stimulated Raman scattering (SRS) excited collectively by two laser pulses. The experiments have been carried out at the LULI facility using two co-propagating 1-μm wavelength, 1.5-ps duration laser pulses focused in a preformed underdense plasma. A particular emphasis is laid on the configuration where the pulses are focused side-by-side, with a lateral distance of 80–90 μm, but not simultaneously. It is experimentally demonstrated that a weak-intensity speckle, ineffective when fired alone in a preformed plasma, yields a significant SRS-induced reflectivity if launched a few picoseconds after a strong one. The data have been obtained by using both highly space-time resolved Thomson diagnostics and space-resolved SRS reflectivity measurements. By choosing either parallel or orthogonal polarizations for the two laser pulses, our experiments shed light on the role of either electrostatic or electromagnetic seeding in enhancing SRS from weak-intensity speckles. A major finding is that seeding operates over unexpectedly long times (15–20 ps under our experimental conditions). Similar results are obtained in lower-density plasmas, or when the weak pulse is smoothed by a random phase plate, thus leading to multiple speckle interaction, while the strong pulse is focused within the speckle pattern. The data are discussed with the help of particle-in-cell numerical simulations, which confirm the destabilizing effect of the strong pulse over the weak one after a short transient time.
Anharmonic effects in the quantum cluster equilibrium method
Authors: von Domaros Michael , Perlt Eva
Published: March 2017

The well-established quantum cluster equilibrium (QCE) model provides a statistical thermodynamic framework to apply high-level ab initio calculations of finite cluster structures to macroscopic liquid phases using the partition function. So far, the harmonic approximation has been applied throughout the calculations. In this article, we apply an important correction in the evaluation of the one-particle partition function and account for anharmonicity. Therefore, we implemented an analytical approximation to the Morse partition function and the derivatives of its logarithm with respect to temperature, which are required for the evaluation of thermodynamic quantities. This anharmonic QCE approach has been applied to liquid hydrogen chloride and cluster distributions, and the molar volume, the volumetric thermal expansion coefficient, and the isobaric heat capacity have been calculated. An improved description for all properties is observed if anharmonic effects are considered.
Suppression of conductivity deterioration of copper thin films by coating with atomic-layer materials
Authors: Cuong Nguyen Thanh , Okada Susumu
Published: March 2017

Theoretical calculations are performed to explore the electronic structures and electron conducting properties of copper (Cu) thin films coated with graphene or h-boron-nitride (h-BN) layers. The Shockley surface states of Cu surfaces are preserved by the graphene and h-BN coatings which prevent the surface oxidation of Cu because of the weak interaction between the Cu surface and graphene or the h-BN layers. Furthermore, the Shockley surface states in Cu thin films possess quasi-two dimensional free-electron characteristics and exhibit a high conductivity of 1.62 × 107 (Ωm)−1 at room temperature. These hybrid structures may be suitable as interconnects in memory devices that can stably store data for long periods.
Neutralization of an epitaxial graphene grown on a SiC(0001) by means of palladium intercalation
Authors: Yagyu Kazuma , Takahashi Kazutoshi , Tochihara Hiroshi , Tomokage Hajime , Suzuki Takayuki
Published: March 2017

Pd-intercalated graphene grown on a SiC(0001) substrate was investigated using STM, angle-resolved photoemission spectroscopy, and XPS. Pd atoms deposited at room temperature on a zero layer graphene grown on a SiC(0001) substrate were intercalated between the zero layer graphene and the SiC substrate after the thermal annealing above 700 °C, forming a Pd-intercalated single layer graphene. No charge transfer occurred between the intercalated Pd layer and the graphene, which resulted in the formation of the electrically neutral graphene. The Pd-intercalated graphene remained electrically neutral throughout the annealing temperature range between 700 and 1100 °C. The charge transfer, however, occurred between the intercalated Pd layer and the SiC substrate, which caused a band bending confirmed in the core level spectra measured by XPS.
Synthesis of tunable plasmonic metal-ceramic nanocomposite thin films by temporally modulated sputtered fluxes
Authors: Magnfält D. , Melander E. , Boyd R. D. , Kapaklis V. , Sarakinos K.
Published: March 2017

The scientific and technological interest for metal-dielectric nanocomposite thin films emanates from the excitation of localized surface plasmon resonances (LSPRs) on the metal component. The overall optical response of the nanocomposite is governed by the refractive index of the dielectric matrix and the properties of the metallic nanoparticles in terms of their bulk optical properties, size, and shape, and the inter-particle distance of separation. In order to tune the film morphology and optical properties, complex synthesis processes which include multiple steps—i.e., film deposition followed by post-deposition treatment by thermal or laser annealing—are commonly employed. In the present study, we demonstrate that the absorption resonances of Ag/AlOxNy nanocomposite films can be effectively tuned from green (∼2.4 eV) to violet (∼2.8 eV) using a single-step synthesis process that is based on modulating the arrival pattern of film forming species with sub-monolayer resolution, while keeping the amount of Ag in the films constant. Our data indicate that the optical response of the films is the result of LSPRs on isolated Ag nanoparticles that are seemingly shifted by dipolar interactions between neighboring particles. The synthesis strategy presented may be of relevance for enabling integration of plasmonic nanocomposite films on thermally sensitive substrates.
Joining of graphene flakes by low energy N ion beam irradiation
Authors: Wu Xin , Zhao Haiyan , Pei Jiayun , Yan Dong
Published: March 2017

An approach utilizing low energy N ion beam irradiation is applied in joining two monolayer graphene flakes. Raman spectrometry and atomic force microscopy show the joining signal under 40 eV and 1 × 1014 cm−2 N ion irradiation. Molecular dynamics simulations demonstrate that the joining phenomenon is attributed to the punch-down effect and the subsequent chemical bond generation between the two sheets. The generated chemical bonds are made up of inserted ions (embedded joining) and knocked-out carbon atoms (saturation joining). The electronic transport properties of the joint are also calculated for its applications.
Energy level engineering in ternary organic solar cells: Evaluating exciton dissociation at organic semiconductor interfaces
Authors: Feron Krishna , Thameel Mahir N. , Al-Mudhaffer Mohammed F. , Zhou Xiaojing , Belcher Warwick J. , Fell Christopher J. , Dastoor Paul C.
Published: March 2017

Electronic energy level engineering, with the aim to improve the power conversion efficiency in ternary organic solar cells, is a complex problem since multiple charge transfer steps and exciton dissociation driving forces must be considered. Here, we examine exciton dissociation in the ternary system poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester:2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (P3HT:PCBM:DIBSq). Even though the energy level diagram suggests that exciton dissociation at the P3HT:DIBSq interface should be efficient, electron paramagnetic resonance and external quantum efficiency measurements of planar devices show that this interface is not capable of generating separated charge carriers. Efficient exciton dissociation is still realised via energy transfer, which transports excitons from the P3HT:DIBSq interface to the DIBSq:PCBM interface, where separated charge carriers can be generated efficiently. This work demonstrates that energy level diagrams alone cannot be relied upon to predict the exciton dissociation and charge separation capability of an organic semiconductor interface and that energy transfer relaxes the energy level constraints for optimised multi-component organic solar cells.
Photoconductivity as a method to probe defects in ultra thin Si films
Authors: Lavrov E. V. , Chaplygin I. , Mchedlidze T.
Published: March 2017

Silicon-on-insulator wafers with thicknesses of a boron doped p-type device layer 1.5 μm to 88 nm are probed by means of photoconductive spectroscopy. It is shown that the boron acceptor manifests itself as Fano resonances at 669 and 693 cm–1 associated with the excited states due to the spin-orbit split-off valence band as well as Γ-phonon replicas of intrinsic boron transitions associated with the states of the top of the valence band. More importantly, electrically neutral oxygen-related defects including interstitial oxygen also appear in the photoconductivity spectra as dips at the frequencies of the corresponding local vibrational modes. These findings demonstrate selectivity and high sensitivity of photoconductive spectroscopy, which make it a preferential technique to probe semiconductor thin films.
Three-dimension isotropic negative permeability material made of eight-split-ring resonator
Authors: Tian Zijian , Wang Xuqi , Li Weixiang , Fan Jing
Published: March 2017

Based on a traditional split-ring resonator, a new type of eight-split-ring resonator structure, capable of providing negative permeability, is proposed in the paper. A three-dimension structure, consisting of three orthogonal eight-split-ring resonators, is a kind of three-dimension isotropic negative permeability structure. Simulation results show that in a three-dimensional space, the magnetic resonance behavior of three-dimensional structure is independent of electromagnetic wave direction and can give negative permeability at the frequency around 4.1GHz. Also, it is demonstrated that the orthogonal pattern in such three-dimension structure does not affect magnetic resonance behavior, facilitating structural analysis and material preparation. The paper provides a reference to the development of metamaterials towards multiple dimensions and directions.
Calcium improves apoplastic–cytosolic ion homeostasis in salt-stressed Vicia faba leaves
Authors: Morgan Sherif H. , Lindberg Sylvia , Maity Pooja Jha , Geilfus Christoph-Martin , Plieth Christoph , Mühling Karl-Hermann
Published: March 2017

Salinity disturbs both apoplastic and cytosolic Ca2+ and pH ([Ca2+]apo, [Ca2+]cyt, pHapo and pHcyt) homeostasis, and decreases plant growth. Seedlings of Vicia faba L. cv. Fuego were cultivated in hydroponics for 7 days under control, salinity (S), extra Ca (Ca) or salinity with extra Ca (S+Ca) conditions. The [Ca2+]apo, and pHapo in the leaves were then recorded in parallel by a pseudoratiometric method, described here for the first time. Lower [Ca2+]apo and higher pHapo were obtained under salinity, whereas extra Ca supply increased the [Ca2+]apo and acidified the pHapo. Moreover, the ratiometric imaging recorded that [Ca2+]cyt and pHcyt were highest in S+Ca plants and lowest in control plants. After all pretreatments, direct addition of NaC6H11O7 to leaves induced a decrease in [Ca2+]apo in control and S+Ca plants, but not in S and Ca plants, and only slightly affected pHapo. Addition of NaCl increased [Ca2+]cyt in protoplasts from all plants but only transiently in protoplasts from S+Ca plants. Addition of NaCl decreased pHcyt in protoplasts from Ca-pretreated plants. We conclude that Ca supply improves both apoplastic and cytosolic ion homeostasis. In addition, NaC6H11O7 probably causes transport of Ca from the apoplast into the cytosol, thereby leading to a higher resting [Ca2+]cyt.
Cytokinins regulate root growth through its action on meristematic cell proliferation but not on the transition to differentiation
Authors: Ivanov Victor B. , Filin Alexey N.
Published: March 2017

Contrary to the wide-spread view that cytokinins change the rate of root growth and meristem size by regulating the cell transition to elongation (differentiation), our data showed that cytokinins affected the cell cycle duration in the meristem. The rate of meristematic cell transition to elongation itself is regulated by two groups of independent processes, through influence on (i) the life-span of cells in the meristem, and (ii) the cell proliferation rate in the meristem. Trans-zeatin slows down the root growth rate and the cell transition to elongation as a result of prolongation of mitotic cycles. The life-span of cells in the meristem does not change. The number of meristematic cells in one file decreases due to inhibition of cell proliferation but not to an acceleration of cell transition to elongation. Roots of triple mutant ipt3ipt5ipt7, in which cytokinin synthesis is slowed down, behave in an opposite way such that the rate of cell transition to elongation and cell proliferation is speeded up. Their peculiarity is that the life-span of cells in meristem becomes shorter than in control roots. In both cases, a change in concentration of endogenous cytokinin or in its signalling are associated with a change in mitotic cycle duration.
Evolving polycentric governance of the Great Barrier Reef
Authors: Morrison Tiffany H.
Published: March 2017

Significance

Global sustainability depends on robust environmental governance regimes. An investigation of the Great Barrier Reef regime between 1975 and 2016 reveals how complex environmental regimes become increasingly structurally dense and eventually reach a point of stabilization. However, structural complexity and stability alone do not necessarily mean the system is robust. Instead, a complex but stable structure can mask exogenous change, which then can generate more endogenous change; this phenomenon has implications for the environmental outcomes of complex regimes. Therefore, it is vital to anticipate and account for change in designing, implementing, and evaluating sustainable environmental governance.
Implanting 8-mm Passive Integrated Transponder Tags into Small Brook Trout: Effects on Growth and Survival in the Laboratory
Authors: J. O'Donnell Matthew , Letcher Benjamin H.
Published: March 2017

Passive integrated transponder (PIT) tags are commonly used to investigate relationships between individual fish and their environment. The recent availability of smaller tags has provided the opportunity to tag smaller fish. In this study, we implanted 8-mm PIT tags into small Brook Trout Salvelinus fontinalis (35–50 mm FL; 0.35–1.266 g) and compared tag retention, growth rates, and survival of PIT-tagged fish with those of fish subjected to handling only or to handling plus fin clipping. We also examined how initial size at tagging affected absolute and specific growth rates of PIT-tagged individuals over time. We found that survival was 100%, tag retention was 96.7%, and fish size did not vary across treatments at 29 and 64 d posttagging. Additionally, there was no evidence that growth rate (FL or mass) was influenced by the initial size of the fish that were PIT tagged. Our results indicate that retention rates of 8-mm PIT tags surgically implanted into small Brook Trout are high and that there is no discernible effect on growth or survival in the laboratory. The ability to implant smaller PIT tags into smaller fish earlier in the season would allow researchers conducting PIT tag studies to expand demographic models to estimate survival of age-0 fish through the summer of their first year.

Received May 27, 2016; accepted March 9, 2017 Published online May 4, 2017
Combination of aerobic exercise and an arginine, alanine, and phenylalanine mixture increases fat mobilization and ketone body synthesis
Authors: Ueda Keisuke , Sanbongi Chiaki , Takai Shoko , Ikegami Shuji , Fujita Satoshi
Published: March 2017

During exercise, blood levels of several hormones increase acutely. We hypothesized that consumption of a specific combination of amino acids (arginine, alanine, and phenylalanine; A-mix) may be involved in secretion of glucagon, and when combined with exercise may promote fat catabolism. Ten healthy male volunteers were randomized in a crossover study to ingest either A-mix (3 g/dose) or placebo (3 g of dextrin/dose). Thirty minutes after ingesting, each condition subsequently performed workload trials on a cycle ergometer at 50% of maximal oxygen consumption for 1 h. After oral intake of A-mix, the concentrations of plasma ketone bodies and adrenalin during and post-exercise were significantly increased. The area under the curve for glycerol and glucagon was significantly increased in the post-exercise by A-mix administration. These results suggest that pre-exercise ingestion of A-mix causes a shift of energy source from carbohydrate to fat combustion by increasing secretion of adrenalin and glucagon.
Trainable Weka Segmentation: a machine learning tool for microscopy pixel classification
Authors: Arganda-Carreras Ignacio , Kaynig Verena , Rueden Curtis , Eliceiri Kevin W , Schindelin Johannes , Cardona Albert , Sebastian Seung H
Published: March 2017

State-of-the-art light and electron microscopes are capable of acquiring large image datasets, but quantitatively evaluating the data often involves manually annotating structures of interest. This process is time-consuming and often a major bottleneck in the evaluation pipeline. To overcome this problem, we have introduced the Trainable Weka Segmentation (TWS), a machine learning tool that leverages a limited number of manual annotations in order to train a classifier and segment the remaining data automatically. In addition, TWS can provide unsupervised segmentation learning schemes (clustering) and can be customized to employ user-designed image features or classifiers.

Availability and Implementation

TWS is distributed as open-source software as part of the Fiji image processing distribution of ImageJ at http://imagej.net/Trainable_Weka_Segmentation.

Supplementary information

Supplementary data are available at Bioinformatics online.
Development of Real-Time Isothermal Amplification Assays for On-Site Detection of Phytophthora infestans in Potato Leaves
Authors: Si Ammour Mélissa , Bilodeau Guillaume J. , Tremblay David Mathieu , Van der Heyden Hervé , Yaseen Thaer , Varvaro Leonardo , Carisse Odile
Published: March 2017

Real-time loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA) assays were developed targeting the internal transcribed spacer 2 region of the ribosomal DNA of Phytophthora infestans, the potato late blight causal agent. A rapid crude plant extract (CPE) preparation method from infected potato leaves was developed for on-site testing. The assay’s specificity was tested using several species of Phytophthora and other potato fungal and oomycete pathogens. Both LAMP and RPA assays showed specificity to P. infestans but also to the closely related species P. andina, P. mirabilis, P. phaseoli, and P. ipomoeae, although the latter are not reported as potato pathogen species. No cross-reaction occurred with P. capsici or with the potato pathogens tested, including P. nicotianae and P. erythroseptica. The sensitivity was determined using P. infestans pure genomic DNA added into healthy CPE samples. Both LAMP and RPA assays detected DNA at 50 fg/μl and were insensitive to CPE inhibition. The isothermal assays were tested with artificially inoculated and naturally infected potato plants using a Smart-DART platform. The LAMP assay effectively detected P. infestans in symptomless potato leaves as soon as 24 h postinoculation. A rapid and accurate on-site detection of P. infestans in plant material using the LAMP assay will contribute to improved late blight diagnosis and early detection of infections and facilitate prompt management decisions.
SNP genotyping and parameter estimation in polyploids using low-coverage sequencing data
Authors: Blischak Paul D. , Kubatko Laura S. , Wolfe Andrea D.
Published: March 2017

Motivation:

Genotyping and parameter estimation using high throughput sequencing data are everyday tasks for population geneticists, but methods developed for diploids are typically not applicable to polyploid taxa. This is due to their duplicated chromosomes, as well as the complex patterns of allelic exchange that often accompany whole genome duplication (WGD) events. For WGDs within a single lineage (auto polyploids), inbreeding can result from mixed mating and/or double reduction. For WGDs that involve hybridization (allopolyploids), alleles are typically inherited through independently segregating subgenomes.

Results:

We present two new models for estimating genotypes and population genetic parameters from genotype likelihoods for auto- and allopolyploids. We then use simulations to compare these models to existing approaches at varying depths of sequencing coverage and ploidy levels. These simulations show that our models typically have lower levels of estimation error for genotype and parameter estimates, especially when sequencing coverage is low. Finally, we also apply these models to two empirical data sets from the literature. Overall, we show that the use of genotype likelihoods to model non-standard inheritance patterns is a promising approach for conducting population genomic inferences in polyploids.

Availability:

A C++ program, EBG, is provided to perform inference using the models we describe. It is available under the GNU GPLv3 on GitHub:

https://github.com/pblischak/polyploid-genotyping.

Contact: blischak.4@osu.edu.
Optimal growth of microbes on mixed carbon sources
Authors: Wang Xin , Tang Chao
Published: March 2017

A classic problem in microbiology is that bacteria display two types of growth behavior when cultured on a mixture of two carbon sources: in certain mixtures the bacteria consume the two carbon sources sequentially (diauxie) and in other mixtures the bacteria consume both sources simultaneously (co-utilization). The search for the molecular mechanism of diauxie led to the discovery of the lac operon and gene regulation in general. However, why microbes would bother to have different strategies of taking up nutrients remained a mystery. Here we show that diauxie versus co-utilization can be understood from the topological features of the metabolic network. A model of optimal allocation of protein resources to achieve maximum growth quantitatively explains why and how the cell makes the choice when facing multiple carbon sources. Our work solves a long-standing puzzle and sheds light on microbes’ optimal growth in different nutrient conditions.
Hydrogen-bonding patterns in bis(cytosinium) tartarate monohydrate
Authors: Jaikumar P. , Sundar T. V. , Sharmila N. , Balakrishnan T. , Ramamurthi K.
Published: March 2017

The asymmetric unit of the title cystosinium salt derivative, 2C4H6N3O+·C4H4O6
2−·H2O, contains two cytosinium cations, one tartaric acid anion and a water molecule. The two cytosinium cations are almost planar (r.m.s. deviations of the fitted atoms are 0.0151 and 0.0213 Å). The crystal structure features C—H...O, N—H...O and O—H...O interactions. Further C—O...π and π–π interactions are observed along the ab plane, contributing to the crystal stability.
Determinants of relationship quality and customer loyalty in retail banking
Authors: Izogo Ernest Emeka , Reza Abdi , Ogba Ike-Elechi , Oraedu Chukwunonso
Published: March 2017

Purpose

The purpose of this paper is to explore the determinants of relationship quality (hereafter referred to as RQ) and its impact on customer loyalty within an emerging retail banking market through a dual-lens theory.

Design/methodology/approach

The research informants were recruited from a city in South-eastern Nigeria. A quantitative data obtained through bank-intercept method and online survey from 332 customers of retail banking services formed the final database. The proposed model and by implication the research hypotheses were tested using partial least squares structural equation modelling procedure.

Findings

The results show that customer orientation, expertise and information sharing are stimulus factors that directly influence the constructs of RQ (i.e. trust and satisfaction and indirectly influence customer loyalty through the constructs of RQ. The paper also demonstrates that the stimulus factors are direct predictors of consumers’ response. The proposed model explained 49 per cent of the total variance in customer loyalty.

Research limitations/implications

Customer orientation, expertise and information sharing are stimulus factors that improve RQ and customer loyalty. However, the explanatory power of the proposed model is modest. Future research should therefore integrate other determinants of RQ.

Practical implications

The paper provides clear insights into how retail bank managers operating in a very competitive and emerging market can improve RQ and subsequently attract customer loyalty.

Originality/value

The paper contributes to the growing body of stimulus-organism-response (S-O-R) literature within the retail environment by exploring unique stimulus and organism variables from an emerging retail banking market perspective. Additionally, by showing that the stimulus factors are direct predictors of consumers’ response, the paper challenged the existing tenets of the S-O-R framework and deepened the current understanding of the model. The paper also contributes to the social exchange theory by demonstrating how the components of RQ mediate the antecedents and consequences of the construct.
Effects of boards on performance of local and foreign-owned banks in Tanzania
Authors: Mori Neema , Towo Goodluck
Published: March 2017

Purpose

The purpose of this paper is to examine the effects of board composition on the profitability of banks in Tanzania. First, it examines the differences between local and foreign-owned banks in terms of their boards and profitability, and then the contribution of board composition to banks’ profitability.

Design/methodology/approach

The paper utilizes a secondary panel data set of information on the boards, their operations and financial statements of 35 banks. The data were collected between 2009 and 2013. The authors tested the stated hypotheses using descriptive and econometric analyses.

Findings

The results show a significant difference in board composition and profitability between local and foreign-owned banks. Local banks have a higher income and profits. With their contextual knowledge they are able to attract diverse board directors who contribute positively to their performance. The paper also found that large boards and those with women on them were associated with high profitability.

Research limitations/implications

The study focused on three aspects of boards, which are size, foreign directors and women’s representation. The paper is limited in the sense that other aspects of composition that also affect performance are not included in the study.

Practical implications

The paper suggests that in order to maximize profitability, banks should increase the number of directors. Many board members can share skills and knowledge, which can improve performance. Women are underrepresented on boards. With current changes in policy and education in emerging countries, there is a need to increase their representation.

Originality/value

This study contributes to the agency theory by showing that large boards are indeed efficient at monitoring and bringing in profits, especially in an emerging economy where there are multifaceted risks at country and company level. These risks require shareholders and investors to have a much better understanding of the banks and that is where a large board plays a key role.