bluuebunny/crossref_metadata_2025 huggingface dataset:
Review and classification of vision‐based localisation techniques in unknown environments
Authors: Ben‐Afia Amani , Deambrogio Lina , Salos Daniel , Escher Anne‐Christine , Macabiau Christophe , Soulier Laurent , Gay‐Bellile Vincent
Published: July 2014

This study presents a review of the state‐of‐the‐art and a novel classification of current vision‐based localisation techniques in unknown environments. Indeed, because of progresses made in computer vision, it is now possible to consider vision‐based systems as promising navigation means that can complement traditional navigation sensors like global navigation satellite systems (GNSSs) and inertial navigation systems. This study aims to review techniques employing a camera as a localisation sensor, provide a classification of techniques and introduce schemes that exploit the use of video information within a multi‐sensor system. In fact, a general model is needed to better compare existing techniques in order to decide which approach is appropriate and which are the innovation axes. In addition, existing classifications only consider techniques based on vision as a standalone tool and do not consider video as a sensor among others. The focus is addressed to scenarios where no a priori knowledge of the environment is provided. In fact, these scenarios are the most challenging since the system has to cope with objects as they appear in the scene without any prior information about their expected position.
Switched Kalman filter‐interacting multiple model algorithm based on optimal autoregressive model for manoeuvring target tracking
Authors: Jin Biao , Jiu Bo , Su Tao , Liu Hongwei , Liu Gaofeng
Published: July 2014

A manoeuvring target tracking algorithm based on the autoregressive (AR) model is proposed. First, the AR model is incorporated into the Kalman filter (KF) for target tracking. The closed‐form solution of the AR model coefficients is obtained by minimising the mean‐square tracking error, and subject to the polynomial constraint of target motion. Then, based on the AR model, the proposed algorithm is constructed by combining the KF with the interacting multiple model (IMM) filter, coupled with the proposed detection schemes for manoeuvre occurrence and termination, as well as for switching initialisation. Simulations are performed to demonstrate the effectiveness of the AR model, and the proposed algorithm is compared with the IMM filter and variable‐dimension filter in the manoeuvring scenario.
Modelling of corona discharge of a tri‐electrode system for electrostatic separation processes
Authors: Abouelsaad Mohamed M.
Published: July 2014

The study presents a detailed experimental and numerical analysis of the corona characteristics of a proposed ‘tri‐electrode system’ for electrostatic separation applications. The system consists of an ionising wire, a movable auxiliary wire and a non‐ionising cylinder, having the same voltage and placed parallel above a grounded plate. A computational technique coupling the method of characteristics and the charge simulation method is developed to model the corona governing equations of the proposed configuration. Influence of the auxiliary wire's position on field modulation of the ionising wire, corona onset and switching on/off of the discharge is established both numerically and experimentally. Dependence of the spatial distributions of the electric field and current density on the system's geometrical characteristics is evaluated and assessed. The study includes a physical model of the corona discharge of this particular electrode arrangement and demonstrates the configuration's specific features and advantages as compared with the earlier designs. The computed results compared favourably well with experiments.
Thermoelectric properties of nanoporous three-dimensional graphene networks
Authors: Thiyagarajan Pradheep , Oh Min-Wook , Yoon Jong-Chul , Jang Ji-Hyun
Published: July 2014

We propose three dimensional-graphene nanonetworks (3D-GN) with pores in the range of 10 ∼ 20 nm as a potential candidate for thermoelectric materials. The 3D-GN has a low thermal conductivity of 0.90 W/mK @773 K and a maximum electrical conductivity of 6660 S/m @ 773 K. Our results suggest a straightforward way to individually control two interdependent parameters, σ and κ, in the nanoporous graphene structures to ultimately improve the figure of merit value.
Soft x-ray backlighting of cryogenic implosions using a narrowband crystal imaging system (invited)
Authors: Stoeckl C. , Bedzyk M. , Brent G. , Epstein R. , Fiksel G. , Guy D. , Goncharov V. N. , Hu S. X. , Ingraham S. , Jacobs-Perkins D. W. , Jungquist R. K. , Marshall F. J. , Mileham C. , Nilson P. M. , Sangster T. C. , Shoup M. J. , Theobald W.
Published: July 2014

A high-performance cryogenic DT inertial confinement fusion implosion experiment is an especially challenging backlighting configuration because of the high self-emission of the core at stagnation and the low opacity of the DT shell. High-energy petawatt lasers such as OMEGA EP promise significantly improved backlighting capabilities by generating high x-ray intensities and short emission times. A narrowband x-ray imager with an astigmatism-corrected bent quartz crystal for the Si Heα line at ∼1.86 keV was developed to record backlit images of cryogenic direct-drive implosions. A time-gated recording system minimized the self-emission of the imploding target. A fast target-insertion system capable of moving the backlighter target ∼7 cm in ∼100 ms was developed to avoid interference with the cryogenic shroud system. With backlighter laser energies of ∼1.25 kJ at a 10-ps pulse duration, the radiographic images show a high signal-to-background ratio of >100:1 and a spatial resolution of the order of 10 μm. The backlit images can be used to assess the symmetry of the implosions close to stagnation and the mix of ablator material into the dense shell.
Monochromatic radiography of high energy density physics experiments on the MAGPIE generator
Authors: Hall G. N. , Burdiak G. C. , Suttle L. , Stuart N. H. , Swadling G. F. , Lebedev S. V. , Smith R. A. , Patankar S. , Suzuki-Vidal F. , de Grouchy P. , Harvey-Thompson A. J. , Bennett M. , Bland S. N. , Pickworth L. , Skidmore J.
Published: July 2014

A monochromatic X-ray backlighter based on Bragg reflection from a spherically bent quartz crystal has been developed for the MAGPIE pulsed power generator at Imperial College (1.4 MA, 240 ns) [I. H. Mitchell et al., Rev. Sci. Instrum. 67, 1533 (2005)]. This instrument has been used to diagnose high energy density physics experiments with 1.865 keV radiation (Silicon He-α) from a laser plasma source driven by a ∼7 J, 1 ns pulse from the Cerberus laser. The design of the diagnostic, its characterisation and performance, and initial results in which the instrument was used to radiograph a shock physics experiment on MAGPIE are discussed.
Infrared absorption and Raman scattering spectra of water under pressure via first principles molecular dynamics
Authors: Ikeda Takashi
Published: July 2014

From both the polarized and depolarized Raman scattering spectra of supercritical water a peak located at around 1600 cm−1, attributed normally to bending mode of water molecules, was experimentally observed to vanish, whereas the corresponding peak remains clearly visible in the measured infrared (IR) absorption spectrum. In this computational study a theoretical formulation for analyzing the IR and Raman spectra is developed via first principles molecular dynamics combined with the modern polarization theory. We demonstrate that the experimentally observed peculiar behavior of the IR and Raman spectra for water are well reproduced in our computational scheme. We discuss the origins of a feature observed at 1600 cm−1 in Raman spectra of ambient water.
A theoretical investigation of the (0001) covellite surfaces
Authors: Gaspari Roberto , Manna Liberato , Cavalli Andrea
Published: July 2014

We report on the properties of the (0001) covellites surfaces, which we investigate by periodic slab density functional theory calculations. The absolute surface energies have been computed for all bulk terminations, showing that surfaces terminated by the flat CuS layer are associated with the lowest surface energy. Cleavage is predicted to occur across the [0001] interlayer Cu–S bond. The surfaces obtained by lowest energy cleavage are analyzed in terms of the atomic vertical relaxation, workfunction, and surface band structure. Our study predicts the presence of a shallow pz-derived surface state located 0.26 eV below the Fermi level, which is set to play an important role in the surface reactivity of covellite.
Combined hybrid functional and DFT+U calculations for metal chalcogenides
Authors: Aras Mehmet , Kılıç Çetin
Published: July 2014

In the density-functional studies of materials with localized electronic states, the local/semilocal exchange-correlation functionals are often either combined with a Hubbard parameter U as in the LDA+U method or mixed with a fraction of exactly computed (Fock) exchange energy yielding a hybrid functional. Although some inaccuracies of the semilocal density approximations are thus fixed to a certain extent, the improvements are not sufficient to make the predictions agree with the experimental data. Here, we put forward the perspective that the hybrid functional scheme and the LDA+U method should be treated as complementary, and propose to combine the range-separated Heyd-Scuseria-Ernzerhof (HSE) hybrid functional with the Hubbard U. We thus present a variety of HSE+U calculations for a set of II-VI semiconductors, consisting of zinc and cadmium monochalcogenides, along with comparison to the experimental data. Our findings imply that an optimal value U* of the Hubbard parameter could be determined, which ensures that the HSE+U* calculation reproduces the experimental band gap. It is shown that an improved description not only of the electronic structure but also of the crystal structure and energetics is obtained by adding the U* term to the HSE functional, proving the utility of HSE+U* approach in modeling semiconductors with localized electronic states.
Charging of moving surfaces by corona discharges sustained in air
Authors: Wang Jun-Chieh , Zhang Daihua , Leoni Napoleon , Birecki Henryk , Gila Omer , Kushner Mark J.
Published: July 2014

Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.
Contactless measurement of nonlinear conductivity in the radio-frequency range
Authors: Došlić Marija , Pelc Damjan , Požek Miroslav
Published: July 2014

We have developed a system for contactless measurement of nonlinear conductivity in the radio-frequency band, and over a wide temperature range. A non-resonant circuit is used to electrically excite the sample, and the induced signal is detected by a resonant circuit whose natural frequency matches higher harmonics of the excitation. A simple modification of the probe allows non-resonant detection suitable for stronger signals. Two measurement procedures are proposed that allow significant excitation power variation, up to 150 W. The apparatus has been validated through the measurement of the nonlinear response at the superconducting transition of a high-Tc superconductor, and the nematic transition of an iron pnictide.
Enhanced thermoelectric figure of merit in strained Tl-doped Bi2Se3
Authors: Saeed Y. , Singh N. , Schwingenschlögl U.
Published: July 2014

We explain recent experimental findings on Tl-doped Bi2Se3 by determining the electronic and transport properties by first-principles calculations and semi-classical Boltzmann theory. Though Tl-doping introduces a momentum-dependent spin-orbit splitting, the effective mass of the carriers is essentially not modified, while the band gap is reduced. Tl is found to be exceptional in this respect as other dopants modify the dispersion, which compromises thermoelectricity. Moreover, we demonstrate that only after Tl-doping strain becomes an efficient tool for enhancing the thermoelectric performance. A high figure of merit of 0.86 is obtained for strong p-doping (7 × 1020 cm−3, maximal power factor) at 500 K under 2% tensile strain.
Observation of transient electric fields in particle-in-cell simulation of capacitively coupled discharges
Authors: Sharma S. , Mishra S. K. , Kaw Predhiman K.
Published: July 2014

The analytical prediction of the presence of transient electric field regions between the bulk plasma and sheath edge in radio frequency capacitively coupled plasma (RF-CCP) discharges has been reported by Kaganovich [Phys. Rev. Lett. 89, 265006 (2002)]. In this paper, we have used the semi-infinite particle-in-cell (PIC) simulation technique to verify the theoretical prediction for the existence of transient electric field in the linear regime; it is shown that the PIC simulation results are in good agreement with the results predicted by analytical model in this regime. It is also demonstrated that the linear theory overestimates the transient electric field as one moves from linear to weakly nonlinear regime. The effect of applied RF current density and electron temperature on evolution of transition field and phase mixing regime has been explored.
Particle capture efficiency in a multi-wire model for high gradient magnetic separation
Authors: Eisenträger Almut , Vella Dominic , Griffiths Ian M.
Published: July 2014

High gradient magnetic separation (HGMS) is an efficient way to remove magnetic and paramagnetic particles, such as heavy metals, from waste water. As the suspension flows through a magnetized filter mesh, high magnetic gradients around the wires attract and capture the particles removing them from the fluid. We model such a system by considering the motion of a paramagnetic tracer particle through a periodic array of magnetized cylinders. We show that there is a critical Mason number (ratio of viscous to magnetic forces) below which the particle is captured irrespective of its initial position in the array. Above this threshold, particle capture is only partially successful and depends on the particle's entry position. We determine the relationship between the critical Mason number and the system geometry using numerical and asymptotic calculations. If a capture efficiency below 100% is sufficient, our results demonstrate how operating the HGMS system above the critical Mason number but with multiple separation cycles may increase efficiency.
Communication: Effect of solvophobic block length on critical micelle concentration in model surfactant systems
Authors: Nikoubashman Arash , Panagiotopoulos Athanassios Z.
Published: July 2014

Experimental measurements of the Critical Micelle Concentration (CMC) in diblock copolymer and molecular surfactant systems have shown a cross-over from the exponential decrease at short chain lengths to a much more shallow decay of the CMC when the solvophobic block length was increased. This effect was observed for a wide variety of surfactants, and has been attributed to the collapse of the solvophobic tail group. In order to study this peculiar effect in more detail, we performed grand canonical Monte Carlo simulations of model surfactants in combination with histogram reweighting to obtain the CMC as a function of solvophobic block length. We found that the CMC decreases exponentially with increasing solvophobic block length; no cross-over to a slower decay has been observed, as also expected based on theoretical considerations. These findings suggest that the experimentally measured CMCs may not be true equilibrium values, but that kinetic effects may be influencing the observed cross-over.
Octahedral distortion induced magnetic anomalies in LaMn0.5Co0.5O3 single crystals
Authors: Manna Kaustuv , Bhadram Venkata Srinu , Elizabeth Suja , Narayana Chandrabhas , Anil Kumar P. S.
Published: July 2014

Single crystals of LaMn0.5Co0.5O3 belonging to the ferromagnetic-insulator and distorted perovskite class were grown using a four-mirror optical float zone furnace. The as-grown crystal crystallizes into an orthorhombic Pbnm structure. The spatially resolved 2D Raman scan reveals a strain-induced distribution of transition metal (TM)–oxygen (O) octahedral deformation in the as-grown crystal. A rigorous annealing process releases the strain, thereby generating homogeneous octahedral distortion. The octahedra tilt by reducing the bond angle TM-O-TM, resulting in a decline of the exchange energy in the annealed crystal. The critical behavior is investigated from the bulk magnetization. It is found that the ground state magnetic behavior assigned to the strain-free LaMn0.5Co0.5O3 crystal is of the 3D Heisenberg kind. Strain induces mean field-like interaction in some sites, and consequently, the critical exponents deviate from the 3D Heisenberg class in the as-grown crystal. The temperature-dependent Raman scattering study reveals strong spin-phonon coupling and the existence of two magnetic ground states in the same crystal.
Experimental demonstration of bindingless signal delivery in human cells via microfluidics
Authors: Kuo Ching-Te , Chuang Fang-Tzu , Wu Pei-Yi , Lin Yueh-Chien , Liu Hao-Kai , Huang Guan-Syuan , Tsai Tzu-Ching , Chi Cheng-Yu , Wo Andrew M. , Lee Hsinyu , Lee Si-Chen
Published: July 2014

The cellular signal transduction is commonly believed to rely on the direct “contact” or “binding” of the participating molecule reaction that depends positively on the corresponding molecule concentrations. In living systems, however, it is somewhat difficult to precisely match the corresponding rapid “binding,” depending on the probability of molecular collision, existing in the cellular receptor-ligand interactions. Thus, a question arises that if there is another mechanism (i.e., bindingless) that could promote this signal communication. According to this hypothesis, we report a cellular model based on the examination of intracellular calcium concentration to explore whether the unidentified signal delivery in cells exists, via a microfluidic device. This device was designed to isolate the cells from directly contacting with the corresponding ligands/molecules by the particular polydimethylsiloxane (PDMS) membranes with different thicknesses. Results show a significant increment of calcium mobilization in human prostate cancer PC-3 cells by the stimulation of endothelin-1, even up to a separated distance of 95 μm. In addition, these stimulated signals exhibited a bump-shaped characteristics depending on the membrane thickness. When the PDMS membrane is capped by SiO2, a particular trait that resembles the ballistic signal conduction was observed. A theoretical model was developed to describe the signal transport process across the PDMS membrane. Taken together, these results indicate that the unidentified signal (ligand structural information) delivery could occur in cells and be examined by the proposed approach, exhibiting a bindingless communication manner. Moreover, this approach and our finding may offer new opportunities to establish a robust and cost-effective platform for the study of cellular biology and new drug development.
Thermoelectric infrared microsensors based on a periodically suspended thermopile integrating nanostructured Ge/SiGe quantum dots superlattice
Authors: Ziouche K. , Savelli G. , Bougrioua Z. , Hauser D. , Lejeune P. , Michon P.-M. , Lasri T. , Leclercq D.
Published: July 2014

This paper presents an original integration of polycrystalline SiGe-based quantum dots superlattices (QDSL) into Thermoelectric (TE) planar infrared microsensors (μSIR) fabricated using a CMOS technology. The nanostructuration in QDSL results into a considerably reduced thermal conductivity by a factor up to 10 compared to the one of standard polysilicon layers that are usually used for IR sensor applications. A presentation of several TE layers, QDSL and polysilicon, is given before to describe the fabrication of the thermopile-based sensors. The theoretical values of the sensitivity to irradiance of μSIR can be predicted thanks to an analytical model. These findings are used to interpret the experimental measurements versus the nature of the TE layer exploited in the devices. The use of nanostructured QDSL as the main material in μSIR thermopile has brought a sensitivity improvement of about 28% consistent with theoretical predictions. The impact of QDSL low thermal conductivity is damped by the contribution of the thermal conductivity of all the other sub-layers that build up the device.
High carrier mobility in ultrapure diamond measured by time-resolved cyclotron resonance
Authors: Akimoto Ikuko , Handa Yushi , Fukai Katsuyuki , Naka Nobuko
Published: July 2014

We have performed time-resolved cyclotron resonance measurements in ultrapure diamond crystals for the temperature range of T=7.3–40 K and obtained the temperature-dependent momentum relaxation times based on the cyclotron resonance widths for optically generated electrons and holes. The relaxation time follows a T−3/2 law down to 12 K, which is expected for acoustic-phonon scattering without impurity effect because of the high purity of our samples. The deviation from the law at lower temperatures is explained by the impurity scattering and the breakdown of the high-temperature approximation for the phonon scattering. We extract the carrier drift mobility by using the directly measured effective masses and the relaxation times. The mobility at 10 K for 600 ns delay time after optical injection is found to be μe=1.5×106 cm2/V s for the electrons, and μlh=2.3×106 cm2/V s and  μhh=2.4×105 cm2/V s for the light and heavy holes, respectively. These high values are achieved by our high-sensitivity detection for low-density carriers (at <1011 cm−3) free from the carrier-carrier scattering as well as by the suppression of the impurity scattering in the high-purity samples.
Phase-controllable spin wave generation in iron garnet by linearly polarized light pulses
Authors: Yoshimine Isao , Satoh Takuya , Iida Ryugo , Stupakiewicz Andrzej , Maziewski Andrzej , Shimura Tsutomu
Published: July 2014

A phase-controlled spin wave was non-thermally generated in bismuth-doped rare-earth iron garnet by linearly polarized light pulses. We controlled the initial phase of the spin wave continuously within a range of 180° by changing the polarization azimuth of the excitation light. The azimuth dependences of the initial phase and amplitude of the spin wave were attributed to a combination of the inverse Cotton-Mouton effect and photoinduced magnetic anisotropy. Temporally and spatially resolved spin wave propagation was observed with a CCD camera, and the waveform was in good agreement with calculations. A nonlinear effect of the spin excitation was observed for excitation fluences higher than 100 mJ/cm2.
A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation
Authors: Huang Yong , Tao Gang
Published: July 2014

The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.
Highly transparent and flexible InTiO/Ag nanowire/InTiO films for flexible organic solar cells
Authors: Seo Ki-Won , Lee Ju-Hyun , Kim Hyo-Joong , Kim Han-Ki , Na Seok-In
Published: July 2014

We investigated characteristics of Ti-doped In2O3 (TIO)/Ag nanowire (NW)/TIO films as potential transparent and flexible electrodes for flexible organic solar cells. Effective insertion of metallic Ag NW between TIO layers led to improvement of electrical and mechanical properties of sputtered TIO film. At optimized conditions, we achieved a flexible TIO/Ag NW/TIO multilayer with a low sheet resistance of 9.01 Ω/square and a high optical transmittance of 85.14%. In addition, the TIO/Ag NW/TIO multilayer electrode showed small inner and outer bending radius of 5 and 6.5 mm indicating good flexibility. This indicates that hybridization of sputtered TIO films and printed Ag NW network is a promising solution to solve critical problems of high resistance and brittle TIO film and Ag NW network with poor adhesion.
Theoretical model of the polarization Coulomb field scattering in strained AlGaN/AlN/GaN heterostructure field-effect transistors
Authors: Luan Chongbiao , Lin Zhaojun , Lv Yuanjie , Zhao Jingtao , Wang Yutang , Chen Hong , Wang Zhanguo
Published: July 2014

The theoretical model of the polarization Coulomb field scattering (PCF) caused by the polarization charge density variation at the AlGaN/AlN interface in strained AlGaN/AlN/GaN heterostructure field-effect transistors has been developed. And the theoretical values for the electron drift mobility, which were calculated using the Matthiessen's rule that includes PCF, piezoelectric scattering, polar optical-phonon scattering, and interface roughness scattering, are in good agreement with our experimental values. Therefore, the theoretical model for PCF has been confirmed.
Field emission properties from flexible field emitters using carbon nanotube film
Authors: Shin Dong Hoon , Jung Seung Il , Yun Ki Nam , Chen Guohai , Song Yoon-Ho , Saito Yahachi , Milne William I. , Lee Cheol Jin
Published: July 2014

Flexible carbon nanotube (CNT) field emitters are fabricated using CNT films on polyethylene terephthalate films. The flexible CNT emitters, which are made using double-walled CNTs, show high emission performance and also indicate stable field emission properties under several bending conditions. The flexible CNT emitters have a low turn-on field of about 0.82 V/μm and a high emission current density of about 2.0 mA/cm2 at an electric field of 1.6 V/μm. During stability tests, the flexible CNT emitters initially degrade over the first 4 h but exhibit no further significant degradation over the next 16 h testing while being continually bent. A flexible lamp made using the flexible CNT emitter displays uniform and bright emission patterns in a convex mode.
InGaN/GaN multiple-quantum-well light-emitting diodes with a grading InN composition suppressing the Auger recombination
Authors: Zhang Zi-Hui , Liu Wei , Ju Zhengang , Tan Swee Tiam , Ji Yun , Kyaw Zabu , Zhang Xueliang , Wang Liancheng , Sun Xiao Wei , Demir Hilmi Volkan
Published: July 2014

In conventional InGaN/GaN light-emitting diodes (LEDs), thin InGaN quantum wells are usually adopted to mitigate the quantum confined Stark effect (QCSE), caused due to strong polarization induced electric field, through spatially confining electrons and holes in small recombination volumes. However, this inevitably increases the carrier density in quantum wells, which in turn aggravates the Auger recombination, since the Auger recombination scales with the third power of the carrier density. As a result, the efficiency droop of the Auger recombination severely limits the LED performance. Here, we proposed and showed wide InGaN quantum wells with the InN composition linearly grading along the growth orientation in LED structures suppressing the Auger recombination and the QCSE simultaneously. Theoretically, the physical mechanisms behind the Auger recombination suppression are also revealed. The proposed LED structure has experimentally demonstrated significant improvement in optical output power and efficiency droop, proving to be an effective solution to this important problem of Auger recombination.
Mechanical properties of MoS2/graphene heterostructures
Authors: Jiang Jin-Wu , Park Harold S.
Published: July 2014

We perform classic molecular dynamics simulations to comparatively investigate the mechanical properties of single-layer MoS2 and a graphene/MoS2/graphene heterostructure under uniaxial tension. We show that the lattice mismatch between MoS2 and graphene will lead to an spontaneous strain energy in the interface. The Young's modulus of the heterostructure is much larger than that of MoS2. While the stiffness is enhanced, the yield strain of the heterostructure is considerably smaller than the MoS2 due to lateral buckling of the outer graphene layers owning to the applied mechanical tension.
Effect of interwire separation on growth kinetics and properties of site-selective GaAs nanowires
Authors: Rudolph D. , Schweickert L. , Morkötter S. , Loitsch B. , Hertenberger S. , Becker J. , Bichler M. , Abstreiter G. , Finley J. J. , Koblmüller G.
Published: July 2014

We report tuning of the growth kinetics, geometry, and properties of autocatalytic GaAs nanowires (NW) by precisely controlling their density on SiO2-mask patterned Si (111) substrates using selective area molecular beam epitaxy. Using patterned substrates with different mask opening size (40–120 nm) and pitch (0.25–3 μm), we find that the NW geometry (length, diameter) is independent of the opening size, in contrast to non-catalytic GaAs NWs, whereas the NW geometry strongly depends on pitch, i.e., interwire separation and NW density. In particular, two distinct growth regimes are identified: a diffusion-limited regime for large pitches (low NW density) and a competitive growth regime for smaller pitches (high NW density), where axial and radial NW growth rates are reduced. The transition between these two regimes is significantly influenced by the growth conditions and shifts to smaller pitches with increasing As/Ga flux ratio. Ultimately, the pitch-dependent changes in growth kinetics lead to distinctly different photoluminescence properties, highlighting that mask template design is a very critical parameter for tuning intrinsic NW properties.
Solid-state dewetting of Au/Ni bilayers: The effect of alloying on morphology evolution
Authors: Herz A. , Wang D. , Kups Th. , Schaaf P.
Published: July 2014

The solid-state dewetting of thin Au/Ni bilayers deposited onto SiO2/Si substrates is investigated. A rapid thermal treatment is used to induce the dewetting process by an increase in temperature. The evolution of the (111) peaks of X-ray diffraction reveals a characteristic change due to mixing of Au and Ni. At low temperature, the Au-Ni thin film is found to break up at the phase boundaries and growing voids are shown to be surrounded by a Ni-rich phase. Branch-like void growth is observed. Upon annealing at increasing temperatures, Au-Ni solid solutions are formed well above the bulk equilibrium solubility of Au and Ni. It is found that this metastable phase formation makes the Au-Ni thin film less vulnerable to rupturing. Moreover, growth mode of still evolving voids changes into a more regular, faceted one due to alloying. Finally, it is shown that annealing above the miscibility gap forms supersaturated, well-oriented Au-Ni solid solution agglomerates via dewetting.
Shear strain mediated magneto-electric effects in composites of piezoelectric lanthanum gallium silicate or tantalate and ferromagnetic alloys
Authors: Sreenivasulu G. , Qu P. , Piskulich E. , Petrov V. M. , Fetisov Y. K. , Nosov A. P. , Qu Hongwei , Srinivasan G.
Published: July 2014

Shear strain mediated magneto-electric (ME) coupling is studied in composites of piezoelectric Y-cut lanthanum gallium silicate (LGS) or tantalate (LGT) and ferromagnetic Fe-Co-V alloys. It is shown that extensional strain does not result in ME effects in these layered composites. Under shear strain generated by an ac and dc bias magnetic fields along the length and width of the sample, respectively, strong ME coupling is measured at low-frequencies and at mechanical resonance. A model is discussed for the ME effects. These composites of Y-cut piezoelectrics and ferromagnetic alloys are of importance for shear strain based magnetic field sensors.
Modelling the effect of plant water use traits on yield and stay-green expression in sorghum
Authors: Kholová Jana , Murugesan Tharanya , Kaliamoorthy Sivasakthi , Malayee Srikanth , Baddam Rekha , Hammer Graeme L. , McLean Greg , Deshpande Santosh , Hash C. Thomas , Craufurd Peter Q. , Vadez Vincent
Published: July 2014

Post-rainy sorghum (Sorghum bicolor (L.) Moench) production underpins the livelihood of millions in the semiarid tropics, where the crop is affected by drought. Drought scenarios have been classified and quantified using crop simulation. In this report, variation in traits that hypothetically contribute to drought adaptation (plant growth dynamics, canopy and root water conducting capacity, drought stress responses) were virtually introgressed into the most common post-rainy sorghum genotype, and the influence of these traits on plant growth, development, and grain and stover yield were simulated across different scenarios. Limited transpiration rates under high vapour pressure deficit had the highest positive effect on production, especially combined with enhanced water extraction capacity at the root level. Variability in leaf development (smaller canopy size, later plant vigour or increased leaf appearance rate) also increased grain yield under severe drought, although it caused a stover yield trade-off under milder stress. Although the leaf development response to soil drying varied, this trait had only a modest benefit on crop production across all stress scenarios. Closer dissection of the model outputs showed that under water limitation, grain yield was largely determined by the amount of water availability after anthesis, and this relationship became closer with stress severity. All traits investigated increased water availability after anthesis and caused a delay in leaf senescence and led to a ‘stay-green’ phenotype. In conclusion, we showed that breeding success remained highly probabilistic; maximum resilience and economic benefits depended on drought frequency. Maximum potential could be explored by specific combinations of traits.
Variations in epithelial Na+ transport and epithelial sodium channel localisation in the vaginal cul-de-sac of the brushtail possum, Trichosurus vulpecula, during the oestrous cycle
Authors: Alsop T.-A. , McLeod B. J. , Butt A. G.
Published: July 2014

The fluid in the vaginal cul-de-sac of the brushtail possum, Trichosurus vulpecula, is copious at ovulation when it may be involved in sperm transport or maturation, but is rapidly reabsorbed following ovulation. We have used the Ussing short-circuit current (Isc) technique and measurements of transcript and protein expression of the epithelial Na+ channel (ENaC) to determine if variations in electrogenic Na+ transport are associated with this fluid absorption. Spontaneous Isc (<20 µA cm–2 during anoestrus, 60–80 µA cm–2 in cycling animals) was inhibited by serosal ouabain. Mucosal amiloride (10 µmol L–1), an inhibitor of ENaC, had little effect on follicular Isc but reduced luteal Isc by ~35%. This amiloride-sensitive Isc was dependent on mucosal Na+ and the half-maximal inhibitory concentration (IC50)–amiloride (0.95 μmol L–1) was consistent with ENaC-mediated Na+ absorption. Results from polymerase chain reaction with reverse transcription (RT-PCR) indicate that αENaC mRNA is expressed in anoestrous, follicular and luteal phases. However, in follicular animals αENaC immunoreactivity in epithelial cells was distributed throughout the cytoplasm, whereas immunoreactivity was restricted to the apical pole of cells from luteal animals. These data suggest that increased Na+ absorption contributes to fluid absorption during the luteal phase and is regulated by insertion of ENaC into the apical membrane of cul-de-sac epithelial cells.
Pity: a mitigated defence
Authors: Kristjánsson Kristján
Published: July 2014

The aim of this article is to offer a mitigated moral justification of a much maligned emotional trait,pity, in the Aristotelian sense of ‘pain at deserved bad fortune’. I lay out Aristotle’s taxonomic map of pity and its surrounding conceptual terrain and argue – by rehearsing modern accounts – that this map is not anachronistic with respect to contemporary conceptions. I then offer an ‘Aristotelian’ (albeit not Aristotle’s) moral justification of pity, not as a full virtue intrinsically related toeudaimoniabut as a positive moral quality that has instrumental value in developing and sustaining a certain intrinsically valuable state of character – namely compassion. The justification offered is mitigated in the sense that it does not elevate pity to a virtuous disposition, constitutive of the good life; yet it does offer a crucial counterweight to Aristotle’s own denunciation of pity.
Eclecticism and commonality in employee constructions of spirituality
Authors: Crossman Joanna
Published: July 2014

Determining how to manage spiritual diversity in a globalized Australia and developing organizational strategies to that end is a complex undertaking. As a starting point, the process requires empirical evidence around how employees and managers construct and perceive spirituality in
Australian workplace contexts. Much of the literature around workplace spirituality and the theorizing about spirituality as a concept has been generated in the United States. Whilst this body of work provides rich insights, little is known about its transferability across cultures or more
specifically, whether spirituality is perceived in working Australia in ways comparable to the United States. This paper reports on a grounded theory study that aimed to discover how participating managers and professionals constructed spirituality in the context of their workplace experience.
The findings revealed a high level of individual spiritual eclecticism and dynamism in the way participants perceived and experienced spirituality. Common spiritual values were also identified across the data. The author concludes that spiritual eclecticism appears to be an under-researched
and possibly under-appreciated concept and argues that common values may well provide the necessary “glue” for managing spiritual diversity and fostering spiritual inclusiveness in organizations.
Skeletons in the broom closet: exploring the discrimination of Pagans in the workplace
Authors: Tejeda Manuel J.
Published: July 2014

Paganism encompasses many faiths that have folk or ethnic origins and further represents an understudied minority despite being one of the fastest growing religions in the United States, Canada, and UK. The current research examines the experiences of Pagans at work in two studies. Study 1 reports on a series of narrative interviews into the lived experiences of Pagans in the workplace. Study 2 employs quantitative methods to examine hypotheses generated by Study 1. Findings suggest that workplace ridicule and discrimination against Pagans is commonplace, including higher levels of covert and overt victimization and lower job satisfaction among Pagans when compared to other mainline faiths in the workplace. Limitations, directions for future research, and implications for management are discussed.
Asymmetrical hyperpolyglot potential in women? – Looking at linguistic chauvinism in the twenty-first century
Authors: Pandey Anjali
Published: July 2014

This article focuses on renditions of hyperglossia in a recently published popular linguistics text entitled Babel No More. The article aims to examine in detail the seemingly asymmetrical portrayal of female polyglot prowess relative to spotlighted male linguistic proficiency in the extensive diachronic and synchronic case studies presented in the text and presents historical evidence of female polyglot contributions – past and present – to fill a perceived gap in the proffered record in this widely circulating twenty-first-century text. The seeming contrast of awe for language accumulators versus doubt for actual multilingual competence in a book bearing the subtitle The Search for the World’s Most Extraordinary Language Learners it is argued needs discoursal scrutiny both for what is says and for its brilliant use of covert linguistic strategies to revive and reconstruct eighteenth-century accounts of global asymmetry in women’s cognitive potential 300 years later. By examining three brilliantly crafted critical discourse strategies of Underdefinition, Underreportage; and Selective Visualization, which author Erard employs to simultaneously and systematically “other,” marginalize and trivialize some multilingual speakers while privileging past and present male hyperpolyglots in particular regions of the world, we understand how global exhibitionism of power and cultural knowledge is both revived and sustained in a seemingly interconnected and deterritorialized world of “cosmopolitan” access in the twenty-first century. Eventually then, this article seeks to examine what we lose when we limit ourselves to agenda rather than the pursuit of actual historical and present-day truths with globally spanning rather than regionally oriented evidence. Indeed, the article prods readers to consider what we risk to lose in fields as esoteric as linguistics when current analyses fail to focus on 51% of the world’s population – women.
Med13p prevents mitochondrial fission and programmed cell death in yeast through nuclear retention of cyclin C
Authors: Khakhina Svetlana , Cooper Katrina F. , Strich Randy
Published: July 2014

The yeast cyclin C-Cdk8 kinase forms a complex with Med13p to repress the transcription of genes involved in the stress response and meiosis. In response to oxidative stress, cyclin C displays nuclear to cytoplasmic relocalization that triggers mitochondrial fission and promotes programmed cell death. In this report, we demonstrate that Med13p mediates cyclin C nuclear retention in unstressed cells. Deleting MED13 allows aberrant cytoplasmic cyclin C localization and extensive mitochondrial fragmentation. Loss of Med13p function resulted in mitochondrial dysfunction and hypersensitivity to oxidative stress–induced programmed cell death that were dependent on cyclin C. The regulatory system controlling cyclin C-Med13p interaction is complex. First, a previous study found that cyclin C phosphorylation by the stress-activated MAP kinase Slt2p is required for nuclear to cytoplasmic translocation. This study found that cyclin C-Med13p association is impaired when the Slt2p target residue is substituted with a phosphomimetic amino acid. The second step involves Med13p destruction mediated by the 26S proteasome and cyclin C-Cdk8p kinase activity. In conclusion, Med13p maintains mitochondrial structure, function, and normal oxidative stress sensitivity through cyclin C nuclear retention. Releasing cyclin C from the nucleus involves both its phosphorylation by Slt2p coupled with Med13p destruction.
Nuclear factor of activated T-cells 5 increases intestinal goblet cell differentiation through an mTOR/Notch signaling pathway
Authors: Zhou Yuning , Wang Qingding , Weiss Heidi L. , Evers B. Mark
Published: July 2014

The intestinal mucosa undergoes a continual process of proliferation, differentiation, and apoptosis that is regulated by multiple signaling pathways. Previously, we have shown that the nuclear factor of activated T-cells 5 (NFAT5) is involved in the regulation of intestinal enterocyte differentiation. Here we show that treatment with sodium chloride (NaCl), which activates NFAT5 signaling, increased mTORC1 repressor regulated in development and DNA damage response 1 (REDD1) protein expression and inhibited mTOR signaling; these alterations were attenuated by knockdown of NFAT5. Knockdown of NFAT5 activated mammalian target of rapamycin (mTOR) signaling and significantly inhibited REDD1 mRNA expression and protein expression. Consistently, overexpression of NFAT5 increased REDD1 expression. In addition, knockdown of REDD1 activated mTOR and Notch signaling, whereas treatment with mTOR inhibitor rapamycin repressed Notch signaling and increased the expression of the goblet cell differentiation marker mucin 2 (MUC2). Moreover, knockdown of NFAT5 activated Notch signaling and decreased MUC2 expression, while overexpression of NFAT5 inhibited Notch signaling and increased MUC2 expression. Our results demonstrate a role for NFAT5 in the regulation of mTOR signaling in intestinal cells. Importantly, these data suggest that NFAT5 participates in the regulation of intestinal homeostasis via the suppression of mTORC1/Notch signaling pathway.
Multinational Retailers and Home Country Food Exports
Authors: Cheptea Angela , Emlinger Charlotte , Latouche Karine
Published: July 2014

This article questions whether food exports to a given national market are impacted by a domestic retailer opening in that market. To answer this question, we considered an empirical gravity‐type trade model. We tested our model with data on bilateral exports of food products sold in supermarkets (groceries) on a large panel of countries, as well as the foreign grocery sales of the world's 100 largest retail companies from 2001–2010. We found a strong positive effect of the overseas presence of retailers from a given country on its exports to those markets. This outcome is far from trivial since most products sold in retailers' foreign outlets are produced locally, and it also testifies to the fact that the presence of a country's retail companies overseas helps reduce export costs to these markets for other firms from the retailers' country of origin. On average, a 10% increase in retailers' sales in a foreign country leads to a 2.1%–2.5% increase in food exports to this destination. Our result is robust to different specifications, the use of different sets of instrumental variables, and econometric approaches. The effects on exported values and quantities are similar, implying that our finding is not induced by price or quality upgrading.
Child health
Authors: Simon Chantal , Everitt Hazel , van Dorp Françoise , Burkes Matt
Published: July 2014

Child health promotion

The neonatal check

Neonatal bloodspot screening

Summary of developmental milestones

Screening for hip dysplasia

Vision and hearing screening tests

Birth trauma

Genetic problems

Minor problems of neonates and small babies

Problems of prematurity

Neonatal jaundice

Feeding babies

Weaning, feeding problems, and failure to thrive...