bluuebunny/crossref_metadata_2025 huggingface dataset:
Tunable resonant spectra through nanometer niobium grating on silicon nitride membrane
Authors: Lee Huang-Ming , Lin Chu-Ying , Horng Lance , Wu Jong-Ching
Published: April 2010

Transmission characteristics at visible light range in a designed superconducting niobium grating on the silicon nitride membrane have been numerically analyzed based on the finite element method in conjunction with a two-fluid model. The niobium strips are premeditated to possess a trapezoid cross section, giving rise to an extra tuning parameter of top/bottom width. The simulation results clearly reveal that the resonant features of transmittance spectra of the superconducting system can be altered by the spacing, the geometry parameters of the superconducting grating, and the ambient temperature of the system. It is found that the positions of the resonant peaks can be manipulated either by the spacing of the grating or the bottom width of the trapezoid cross section of the superconducting strip or their combinations. In addition, the transmission resonances possess higher quality factors when either decreasing the height and the top width of the trapezoid cross section of the superconducting strip or increasing the temperature close to the critical temperature of the superconductor.
Constructing smooth potentials of mean force, radial distribution functions, and probability densities from sampled data
Authors: van Zon Ramses , Schofield Jeremy
Published: April 2010

In this paper a method of obtaining smooth analytical estimates of probability densities, radial distribution functions, and potentials of mean force from sampled data in a statistically controlled fashion is presented. The approach is general and can be applied to any density of a single random variable. The method outlined here avoids the use of histograms, which require the specification of a physical parameter (bin size) and tend to give noisy results. The technique is an extension of the Berg–Harris method [B. A. Berg and R. C. Harris, Comput. Phys. Commun. 179, 443 (2008)], which is typically inaccurate for radial distribution functions and potentials of mean force due to a nonuniform Jacobian factor. In addition, the standard method often requires a large number of Fourier modes to represent radial distribution functions, which tends to lead to oscillatory fits. It is shown that the issues of poor sampling due to a Jacobian factor can be resolved using a biased resampling scheme, while the requirement of a large number of Fourier modes is mitigated through an automated piecewise construction approach. The method is demonstrated by analyzing the radial distribution functions in an energy-discretized water model. In addition, the fitting procedure is illustrated on three more applications for which the original Berg–Harris method is not suitable, namely, a random variable with a discontinuous probability density, a density with long tails, and the distribution of the first arrival times of a diffusing particle to a sphere, which has both long tails and short-time structure. In all cases, the resampled, piecewise analytical fit outperforms the histogram and the original Berg–Harris method.
Size-driven magnetic transitions in monodisperse MnO nanocrystals
Authors: Lee Yi-Cheng , Pakhomov Alexandre B. , Krishnan Kannan M.
Published: April 2010

We report the observation of weak ferromagnetism up to TC≈250 K and a spin-glass-like behavior at temperatures below TSG≈30 K in nanoscale MnO particles. TSG is considerably lower and TC is much higher than the Néel temperature (TN=122 K) of bulk MnO. While the dominant low temperature behavior (below 30 K) may be attributed to the effects studied in this system before, such as uncompensated surface spins in antiferromagnetic particles, no manganese oxides have been observed with the Curie temperature as high as 250 K. We explain the magnetic ordering below TC as due to indirect exchange of the type observed in dilute magnetic oxides, which can be mediated by crystal defects and/or surfaces.
Entropy localization in magnetic compounds and thin-film nanostructures
Authors: Skomski R. , Binek Ch. , Michalski S. , Mukherjee T. , Enders A. , Sellmyer D. J.
Published: April 2010

The effect of nanostructuring on the magnetic entropy of materials for room-temperature magnetic cooling is investigated by model calculations. The materials are structurally inhomogeneous with a large number of nonequivalent crystallographic sites. In the mean-field Heisenberg model, the entropy density is a unique function of the local magnetization so that the coupled set of nonlinear mean-field equations yields not only the magnetization but also the entropy density. Since most of the entropy is localized near grain boundaries, nanomagnetic cooling requires small feature sizes. Magnetic anisotropy is a substantial complication, even on a mean-field level, but the corresponding corrections are often very small.
Magnetic antiphase domains in Co/Ru/Co trilayers
Authors: Li Zhen , Skomski Ralph , Michalski Steven , Yue Lanping , Kirby Roger D.
Published: April 2010

Ultrathin Co/Ru/Co trilayers are investigated experimentally by magnetization curves and magnetic-force microscopy (MFM). Emphasis is on the domain-wall fine structure of antiphase domain walls in the films. The trilayers are produced by sputtering and consist of two Co layers of equal thickness (5 nm), exchange-coupled through a Ru layer of variable thickness. The sign and magnitude of the interlayer exchange are tuned by the thickness of the Ru interlayer. The exchange and its distribution are investigated by measurements of the static magnetization curves. For a Ru thickness of 0.4 nm, the exchange is predominantly antiferromagnetic and the MFM images show fairly immobile domain walls. Micromagnetic model calculations yield immobile antiphase domain walls whose thickness decreases with increasing magnetic field but is typically of the order of 100 nm in agreement with experiment.
Plasmon resonance enhancement of magneto-optic effects in garnets
Authors: Mayergoyz I. D. , Lang G. , Hung L. , Tkachuk S. , Krafft C. , Rabin O.
Published: April 2010

Enhancement of magneto-optic effects by strong electric fields induced by plasmon resonances in metallic nanoparticles placed on (or embedded into) garnets is discussed. Theoretical and computational results on excitation of plasmon resonances in such particles are reported and compared to available experimental data.
Magnetic, electrical, and magnetothermal properties in Ni–Co–Mn–Sb Heusler alloys
Authors: Nayak Ajaya K. , Suresh K. G. , Nigam A. K.
Published: April 2010

We have studied the magnetic, magnetoresistance, and thermal properties of Ni50−xCoxMn38Sb12 for x=0–7. The martensitic transition temperature decreases with increase in x and there is no martensitic transition observed for x=8. The martensitic transition is accompanied by a large change in magnetization as well as in electrical resistance. Due to the large change in magnetization, a large magnetic entropy change in 68 and 43 J kg−1 K−1 is observed for x=5 and 4, respectively, around the room temperature. A large magnetoresistance of 34% is observed for x=7. Both the magnetocaloric effect and the magnetoresistance are associated with the martensitic transition, which can be tuned significantly by varying the Ni/Co composition. The results obtained in this system suggest that it may act as a potential magnetic refrigerant as well as a magneto resistive material.
Integrability aspects with optical solitons of a generalized variable-coefficient N-coupled higher order nonlinear Schrödinger system from inhomogeneous optical fibers
Authors: Lü Xing , Li Juan , Zhang Hai-Qiang , Xu Tao , Li Li-Li , Tian Bo
Published: April 2010

For describing the long-distance communication and manufacturing problems of N fields propagation in inhomogeneous optical fibers, we consider a generalized variable-coefficient N-coupled nonlinear Schrödinger system with higher order effects such as the third-order dispersion, self-steepening and self-frequency shift. Using the Painlevé singularity structure analysis, we obtain two cases for this system to admit the Painlevé property. Then for case (1) we derive the optical dark solitons via solving the Hirota bilinear equations; and based on the obtained (2N+1)×(2N+1) Lax pair, we construct the Darboux transformation to obtain the optical bright solitons (including the multisoliton profiles) for case (2). Finally, the features of optical solitons (both dark and bright ones) in inhomogeneous optical fibers are analyzed and graphically discussed.
Persistent supercurrents in ring-shaped Bi2Sr2CaCu2Ox single crystal
Authors: Ma Rongchao , Mansour A. I. , Egilmez M. , Winterfield C. E. , Fan I. , Chow K. H. , Jung J. , Prabhakaran D. , Razavi F.
Published: April 2010

A superconducting ring could be used to simulate the supercurrent conduction, and its interaction with magnetic vortices in a superconducting solenoid, allowing one to investigate the nature of the vortex structure and its pinning in the presence of the persistent supercurrent. The dissipation of the persistent supercurrent has been studied in a ring-shaped high purity single crystal of Bi2Sr2CaCu2Ox in order to obtain the information about the exponent μ, a parameter in the scaling relation between the effective energy barrier against vortex motion Ueff and the persistent current density J. The measurements of the persistent supercurrent decay show a transition from a strongly nonlogarithmic to a logarithmic decay regime with an increasing temperature. In response to a small increase in the concentration of oxygen vacancies μ decreases in the logarithmic decay regime but remains almost constant in the nonlogarithmic one.
Heat capacity anomalies along the critical isotherm in fluid-fluid phase transitions
Authors: Losada-Pérez Patricia , Pérez-Sánchez Germán , Troncoso Jacobo , Cerdeiriña Claudio A.
Published: April 2010

The behavior of the isochoric heat capacity of pure fluids and the isobaric heat capacity at constant composition of binary mixtures along isothermal paths of approach to liquid-gas and liquid-liquid critical points is studied. From the complete scaling formulation of fluid-fluid criticality, explicit expressions for the critical amplitudes of the leading |Y−Yc|−α/β (where Y can be the density or the mole fraction) contributions are found to reveal previously discovered features of the scaling function, whereas the nature of the most important asymmetry-related terms is characterized. Data for pure toluene and for the binary mixture nitromethane-isobutanol are described within experimental uncertainty using the |Y−Yc|−α/β singularity plus a linear term. Extensive data for mixtures allow proper visualization of the topological features of the heat capacity-density-temperature surface in the critical region.
An iterative, fast, linear-scaling method for computing induced charges on arbitrary dielectric boundaries
Authors: Tyagi Sandeep , Süzen Mehmet , Sega Marcello , Barbosa Marcia , Kantorovich Sofia S. , Holm Christian
Published: April 2010

Simulating coarse-grained models of charged soft-condensed matter systems in presence of dielectric discontinuities between different media requires an efficient calculation of polarization effects. This is almost always the case if implicit solvent models are used near interfaces or large macromolecules. We present a fast and accurate method (ICC⋆) that allows to simulate the presence of an arbitrary number of interfaces of arbitrary shape, each characterized by a different dielectric permittivity in one-, two-, and three-dimensional periodic boundary conditions. The scaling behavior and accuracy of the underlying electrostatic algorithms allow to choose the most appropriate scheme for the system under investigation in terms of precision and computational speed. Due to these characteristics the method is particularly suited to include nonplanar dielectric boundaries in coarse-grained molecular dynamics simulations.
Prediction of variation in critical current with applied tensile/bending strain of Bi2223 composite tape from tensile stress-strain curve
Authors: Ochiai S. , Okuda H. , Sugano M. , Hojo M. , Osamura K.
Published: April 2010

An approach to predict the variation in critical current with applied tensile/bending strain of Bi2223/Ag/Ag alloy composite tapes from the tensile stress-strain curves was presented. Three different fabrication-route samples were used to examine the applicability of the present approach. The damage strain parameter, referring to the difference between the tensile fracture strain and residual strain of Bi2223 filaments along the sample length direction (current transport direction), was estimated from the variation in the slope of the tensile stress-strain curve. With the estimated damage strain parameter, the irreversible tensile strain for critical current was predicted, which agreed well with the experimental result in all samples. Also by substituting the estimated damage strain parameter into the core shape—incorporated model, the critical current-bending strain curve was predicted, which described satisfactorily the experimental result in all samples. The present approach could be a useful tool for prediction of critical current-dependence on applied tensile/bending strain.
Effective potentials for ion-ion and charge-atom interactions of dense semiclassical plasma
Authors: Ramazanov T. S. , Dzhumagulova K. N. , Gabdullin M. T.
Published: April 2010

Using the dielectric function method, the effective interaction potential between ions in a dense semiclassical plasma is investigated. For the case of a partially ionized strongly coupled plasma, the effective potential of charge-unperturbed atom interaction is presented. Both effective potentials are screened. To obtain these potentials the dielectric function is used, taking into account the quantum diffraction effects in electron-electron interactions.
Calculation of complex permeability of magnetic composite materials using ferromagnetic resonance model
Authors: Neo C. P. , Yang Y. , Ding J.
Published: April 2010

The Landau–Lifshitz–Gilbert (LL-G) formula has been widely used in modeling of complex permeability of magnetic thin films and particle composites. In this paper, a approach which is based on Landau–Lifshitz ferromagnetic resonance (LL-FMR) model has been developed to calculate the complex permeability of magnetic particles/insulator matrix composite. It has found that the LL-FMR model can be used to compute the intrinsic permeability of a magnetic particle with different alignments of its magnetic domains with the respect to the incident wave. Through integration with respect to its resonant frequency, this method offers a neat closed-form formula for the case of isotropic composite. Its results compared relatively well with our previous method which computes the isotropic permeability by taking the average of the permeability of a large number of randomly oriented magnetic domains with respect to incident wave based on the LL-G model. For carbonyl bcc-Fe and Fe3O4, the calculated permeability agrees relatively well with the measurement results.
Impedance-matched three-dimensional beam expander and compressor designs via transformation optics
Authors: Emiroglu Caglar D. , Kwon Do-Hoon
Published: April 2010

Based on the coordinate transformation technique, a three-dimensional beam expander/compressor design is presented. Spatial coordinates in two orthogonal directions tangential to the device boundary are scaled at the same rate. The reflection and transmission coefficients are obtained in a closed form at the planar boundary for a plane wave illumination at an arbitrary incidence angle. The reflection and transmission characteristics under two-dimensional Gaussian beam illuminations are analyzed by constructing the incident, reflected, and transmitted waves as a superposition of plane wave components via Fourier transform. Numerical examples are provided to demonstrate the small amount of reflection compared with two-dimensional counterparts of the expander/compressor.
A cubic-anvil high-pressure device for pulsed neutron powder diffraction
Authors: Abe J. , Arakawa M. , Hattori T. , Arima H. , Kagi H. , Komatsu K. , Sano-Furukawa A. , Uwatoko Y. , Matsubayashi K. , Harjo S. , Moriai A. , Ito T. , Aizawa K. , Arai M. , Utsumi W.
Published: April 2010

A compact cubic-anvil high-pressure device was developed for in situ neutron powder diffraction studies. In this device, a cubic shaped pressure medium is compressed by six anvils, and neutron beams pass through gaps between the anvils. The first high-pressure experiment using this device was conducted at J-PARC and clearly showed the neutron diffraction patterns of Pb. Combining the cubic-anvil high-pressure device with a pulsed neutron source will prove to be a useful tool for neutron diffraction experiments.
Wannier-ridge states of He and H− with symmetries P3e and D1o and the validity of classification schemata
Authors: Themelis Spyros I.
Published: April 2010

High lying doubly excited Wannier-ridge states of He and H− with symmetries P3e and D1o are studied and energies and intrinsic characteristics of their wave functions are reported. Energies of these states associated with the hydrogenic threshold up to N=20 are presented and, wherever available, we compare them to other calculations. Proposed classification schemata for these states by approximate collective quantum numbers are examined.
A new electron-methanol molecule pseudopotential and its application for the solvated electron in methanol
Authors: Mones Letif , Turi László
Published: April 2010

A new electron-methanol molecule pseudopotential is developed and tested in the present paper. The formal development of the potential is based on quantum mechanical calculations on the electron-methanol molecule model in the static exchange approximation. The computational model includes a steep confining potential that keeps the otherwise unbound excess electron in the vicinity of the methanol molecule. Using the Phillips–Kleinman theorem we introduce a smooth pseudowave function of the excess electron with the exact eigenenergy and correct asymptotic behavior. The nonlocal potential energy operator of the model Hamiltonian is then replaced to a local potential that reproduces the ground-state properties of the excess electron satisfactorily. The pseudopotential is then optimized in an analytically simple functional form to fit this approximate local potential in conjunction with the point charges and the geometry of a classical, all-site methanol-methanol interaction potential. Of the adjustable parameters, the parameters for the carbon and the methyl hydrogen atoms are optimized, while those for the oxygen and the hydroxyl hydrogen are taken from a previous electron-water molecule pseudopotential. A polarization term is added to the potential a posteriori. The polarization parameters are chosen to reproduce the experimental position of the optical absorption spectrum of an excess electron in mixed quantum-classical molecular dynamics simulations. The energetic, structural and spectroscopic properties of the solvated electron in a methanol bath are simulated at 300 K and compared with previous solvated electron simulations and available experimental data.
Ab initio study of beryllium-decorated fullerenes for hydrogen storage
Authors: Lee Hoonkyung , Huang Bing , Duan Wenhui , Ihm Jisoon
Published: April 2010

We have found that a beryllium (Be) atom on nanostructured materials with H2 molecules generates a Kubas-like dihydrogen complex [Lee, Huang, Duan, and Ihm, Appl. Phys. Lett. 96, 143120 (2010)]. Here, we investigate the feasibility of Be-decorated fullerenes for hydrogen storage using ab initio calculations. We find that the aggregation of Be atoms on pristine fullerenes is energetically preferred, resulting in the dissociation of the dihydrogen. In contrast, for boron (B)-doped fullerenes, Be atoms prefer to be individually attached to B sites of the fullerenes, and a maximum of one H2 molecule binds to each Be atom in a form of dihydrogen with a binding energy of ∼0.3 eV. Our results show that individual dispersed Be-decorated B-doped fullerenes can serve as a room-temperature hydrogen storage medium.
Structural changes in precipitated silica induced by external forces
Authors: Schneider Gerald Johannes , Göritz Dietmar
Published: April 2010

The morphology of pure precipitated silica, silica filled in polydimethylsiloxane rubber, and silica filled in styrene butadiene rubber was studied by means of small-angle X-ray scattering experiments. The silica at a length scale of a few nanometers consists of primary particles, which form aggregates, and clusters with aggregates as basic units. It is evidenced that the aggregate branching, represented by the mass fractal dimension, and the aggregate diameter are different if pure silica and silica in rubber are compared. Contrary, the size of the primary particles and their surface are not influenced. It is demonstrated that the change in the aggregate morphology is due to the external mechanical forces appearing during the mixing process. This is achieved by model experiments using a pistil and a mortar and a composite with different silica fractions. By that means, a systematic change in the morphology with grinding time is observed. Then, the experiments on the composite demonstrate that the major contributions to the mass fractal dimensions are due to the external mechanical forces. In order to test reproducibility and universal validity in the case of precipitated silicas, independent experiments on one silica and further silicas are performed. Several important conclusions are obtained from the study. First, it is shown that a comparison of different pure silica samples without knowing their history may be difficult or questionable. Second, it becomes evident that it is not sufficient to provide only a description of the materials, rather than the details of the sample treatment have to be reported. Therefore, solely the characterization of the morphology of the pure silica is not sufficient to be compared to the mechanical properties of the composites.
Thermoelectric properties of polycrystalline In4Se3 and In4Te3
Authors: Shi Xun , Cho Jung Y. , Salvador James R. , Yang Jihui , Wang Hsin
Published: April 2010

High thermoelectric performance of a single crystal layered compound In4Se3 was reported recently. We present here an electrical and thermal transport property study over a wide temperature range for polycrystalline samples of In4Se3 and In4Te3. Our data demonstrate that these materials are lightly doped semiconductors, leading to large thermopower and resistivity. Very low thermal conductivity, below 1 W/m K, is observed. The power factors for In4Se3 and In4Te3 are much smaller when compared with state-of-the-art thermoelectric materials. This combined with the very low thermal conductivity results in the maximum ZT value of less than 0.6 at 700 K for In4Se3.
Electric field effect on the carrier capture of deep traps in p-type InP
Authors: Darwich R. , Sabra M. K.
Published: April 2010

The electric field effect on the carrier capture cross section of deep traps has been studied. The experimental results on the H4F and H5 hole traps in p-type InP show an enhancement of the capture cross section with the increase in the applied electric field. This enhancement depends on the nature of the deep traps and its peak temperature. Increasing the electric field from 4.1×106 to 2.4×107 V/m leads to an increase in the H4F capture cross section by a factor of 3 to 20. While in the case of H5 it increases by a factor of 2 to 5 by increasing the applied electric field from 8.0×106 to 2.4×107 V/m. A theoretical model has been suggested to explain the electric field effect on the capture cross section. This model deals with the cascade and multiphonon processes semiclassically. Applying this model to the above deep traps, we have found that H4F is negatively charged complex and H5 is positively charged complex.
Ferromagnetic signal and unconventional Kondo-like effect in the superconducting Y1−xPrxBa2Cu3O7−δ systems
Authors: Cao Guixin , Li Yuanyuan , Zhang Jincang , Cao Shixun , Cai Chuanbing , Shen Xuechu
Published: April 2010

Electrical and magnetic properties were studied for the Y1−xPrxBa2Cu3O7−δ superconductors with x=0.44–0.48, which was located near the antiferromagnetic (AFM) and superconducting (SC) phase boundaries. An unconventional Kondo-like effect is observed below Tc for x=0.48, where the value of the resistivity minimum ρmin increases with increasing magnetic field H. The transition temperature Tmin first increases and then decreases with increasing field strength. Magnetic measurements show that a small fraction of FM phase appears and coexists with the SC and AFM phases. We discuss these findings from the viewpoints of Kondo scattering and electron-electron interaction, and found that the resistivity minimum below Tc is mainly due to the Kondo scattering. The Kondo scattering is identified as SC phase coexisting with AFM and FM clusters, which is as the Kondo singlets resulting from Pr substitution. This phase-separated state is unstable against the magnetic field which suppresses the SC phase and restores the single Kondo peak at low temperatures.
Particle size reduction: A way to enhanced dielectric properties of magnetocapacitive La2/3Ca1/3MnO3
Authors: Yáñez-Vilar S. , Mira J. , Sánchez-Andújar M. , Castro-García S. , Fondado A. , Rivas J. , Señarís-Rodríguez M. A.
Published: April 2010

We report the optimization of the dielectric properties of La2/3Ca1/3MnO3. This is achieved by synthesizing this material with small particle size, strategy that reduces the conductivity of the sample and its dielectric losses, while retaining a reasonably high dielectric permittivity and a good magnetocapacitive response. In order to further improve the properties of these nanoparticles, we have also prepared core-shell composites La2/3Ca1/3MnO3@SiO2 but in this case the magnetocapacitive effect is strongly reduced.
Analysis of connectivity map: Control to glutamate injured and phenobarbital treated neuronal network
Authors: Kamal Hassan , Kanhirodan Rajan , Srinivas Kalyan V. , Sikdar Sujit K.
Published: April 2010

We study the responses of a cultured neural network when it is exposed to epileptogenesis glutamate injury causing epilepsy and subsequent treatment with phenobarbital by constructing connectivity map of neurons using correlation matrix. This study is particularly useful in understanding the pharmaceutical drug induced changes in the neuronal network properties with insights into changes at the systems biology level.
Room-temperature continuous-wave metal grating distributed feedback quantum cascade lasers
Authors: Carras M. , Maisons G. , Simozrag B. , Garcia M. , Parillaud O. , Massies J. , Marcadet X.
Published: April 2010

We report on the design and elaboration of continuous wave (cw) distributed feedback quantum cascade lasers (QCLs) using a simple metal grating approach without epitaxial regrowth, neither for the grating nor for the thermal extraction. Room temperature cw single monomode QCLs with 30 dB side mode suppression ratio are demonstrated down to 4.5 μm with 20 mW output power and threshold of 1.5 kA cm−2. The beam quality factor (M2) does not exceed 1.22 for both axes. These results are discussed and the key issue of thermal management of the device is emphasized.
(Fe,Si,Al)-based nanocrystalline soft magnetic alloys for cryogenic applications
Authors: Daniil Maria , Osofsky Michael S. , Gubser Donald U. , Willard Matthew A.
Published: April 2010

In this work Al and Si are substituted for Fe in a (Fe,Si,Al)–Nb–B–Cu alloy with the goal of improving its magnetic properties at 77 K. The x-ray diffraction patterns for a series of five alloys annealed at 823 K shows a Fe3(Si,Al) ordered phase with some residual amorphous phase. The lowest coercivity at room temperature was observed for the alloy with composition Fe68Si15.5Al3.5Nb3B9Cu1. At cryogenic temperatures, the saturation magnetization of 99.3 A m2/kg, coercivity of 0.45 A/m, and resistivity of 122 μΩ cm for the Fe63Si17.5Al6Nb3B9Cu1 alloy, compare favorably to commercial alloys at 77 K.
A magnetoelectric memory cell with coercivity state as writing data bit
Authors: Li Zheng , Wang Jing , Lin Yuanhua , Nan C. W.
Published: April 2010

Commercial magnetic recording media employ magnetic-field-induced two different magnetization states ±M to write data. In this paper, we present a magnetic memory cell in which electric-field-induced two different coercive-field Hc states (i.e., low-Hc and high-Hc) rather than ±M are served as writing data bits. A multiferroic magnetoelectric bilayer with Fe0.93Ge0.07 film grown on fully poled ferroelectric BiScO3-PbTiO3 substrate, exhibiting a large electric-field modulation of Hc, is used for illustration of such a prototype electric-write/magnetic-read memory cell which is nonvolatile. The reading process of the different coercive-field Hc information written by electric fields is demonstrated by using magnetoresistance read head.
Nonvolatile resistive switching memory based on amorphous carbon
Authors: Zhuge F. , Dai W. , He C. L. , Wang A. Y. , Liu Y. W. , Li M. , Wu Y. H. , Cui P. , Li Run-Wei
Published: April 2010

Resistive memory effect has been found in carbon nanostructure-based devices by Standley et al. [Nano Lett. 8, 3345 (2008)]. Compared to nanostructures, hydrogenated amorphous carbon (a-C:H) has much more controllable preparation processes. Study on a-C:H-based memory is of great significance to applications of carbon-based electronic devices. We observed nonvolatile resistance memory behaviors in metal/a-C:H/Pt structures with device yield 90%, ON/OFF ratio >100, and retention time >105 s. Detailed analysis indicates that the resistive switching originates from the formation/rupture of metal filaments due to the diffusion of the top electrodes under a bias voltage.
Single charge detection of an electron created by a photon in a g-factor engineered quantum dot
Authors: Kuwahara Makoto , Kutsuwa Takeshi , Ono Keiji , Kosaka Hideo
Published: April 2010

We demonstrate that a single photoelectron can be trapped in a single quantum dot, which is formed by gate-defining with a nearly-zero g-factor quantum well, and a charge state can be detected with a quantum point contact without destruction. The detection yield has a peak of 0.27 at the resonant photon energy of the dot exciton in photon flux of 4.1×10−10 W/mm2. The number-resolved counting statistics revealed that the yield for the second electron trap is drastically decreased from that for the first trap because of the Coulomb-blockade effect. The demonstrated function is essential for making a high-fidelity quantum interface.
Electronic channels for acoustic transport in semiconductor heterostructures
Authors: Biermann K. , Couto O. D. D. , Seidel W. , Hey R. , Santos P. V.
Published: April 2010

We demonstrate electronic waveguides for the ambipolar transport of electrons and holes by surface acoustic waves (SAWs) in buried (Al,Ga)As quantum well (QW) structures, which do not require deep-etching for their fabrication. They are defined by tailoring the SAW-induced piezoelectric potential in the QW plane using thin metal stripes deposited onto the piezoelectric cap layer of the QW sample. Acoustic transport experiments show the enhanced capture and acoustic transport of photoexcited carriers underneath the metallic surface stripes.
Photoinduced charge-trapping phenomena in metal/high-k gate stack structures studied by synchrotron radiation photoemission spectroscopy
Authors: Tanimura T. , Toyoda S. , Kamada H. , Kumigashira H. , Oshima M. , Sukegawa T. , Liu G. L. , Liu Z.
Published: April 2010

We have demonstrated photoinduced charge-trapping phenomena in metal/high-k gate stack structures using time-dependent photoemission spectroscopy with synchrotron radiation. Pt metal gate electrode with a large work function releases trapped negative charges near the surface of the HfSiON film while TiN metal gate electrode with a lower work function keeps negative charges in the HfSiON film. The release of negative trapped charges reveals a possibility of positive charge trapping at the interface in the HfSiON film. The location of energy level for negative charges is concluded to be between Pt and TiN Fermi-level in the band gap of the HfSiON film.
Gate-defined double quantum dot with integrated charge sensors realized in InGaAs/InP by incorporating a high-κ dielectric
Authors: Sun Jie , Larsson Marcus , Maximov Ivan , Xu H. Q.
Published: April 2010

A gate-defined double quantum dot with two integrated quantum point contact charge sensors is realized in an InGaAs/InP heterostructure by employing a high-κ HfO2 thin film as gate dielectric and a polymer bridge technique. Clear honeycomb patterns are observed in the measured charge stability diagram of the double quantum dot and charge sensing signals of the quantum point contacts. It is also found that the quantum point contact charge sensors can detect the charge states in the double quantum dot even in the condition that the direct transport signal is not visible.
Tables of Elastic Scattering Cross Sections of Photons in the Energy Range 50–1500 keV for All Elements in the Range 13⩽Z⩽104
Authors: Chatterjee B. K. , Roy S. C.
Published: April 2010

Tables of differential and total elastic scattering cross sections for 92 elements in the atomic number range 13⩽Z⩽104 and for selected photon energies in the range 50–1500 keV have been presented. The energies are chosen to cover the most commonly used photon energies and in a suitable grid so as to enable one to use the usual interpolation methods to determine cross sections for any other energies in this energy range. The available experimental results are also compared with the tabulated values and the difference is presented graphically.
The Observed Properties of Liquid Helium at the Saturated Vapor Pressure
Authors: Donnelly Russell J. , Barenghi Carlo F.
Published: April 2010

The equilibrium and transport properties of liquid He4 are deduced from experimental observations at the saturated vapor pressure. In each case, the bibliography lists all known measurements. Quantities reported here include density, thermal expansion coefficient, dielectric constant, superfluid and normal fluid densities, first, second, third, and fourth sound velocities, specific heat, enthalpy, entropy, surface tension, ion mobilities, mutual friction, viscosity and kinematic viscosity, dispersion curve, structure factor, thermal conductivity, latent heat, saturated vapor pressure, thermal diffusivity and Prandtl number of helium I, and displacement length and vortex core parameter in helium II.
Isotopic Compositions of the Elements 1997
Authors: Rosman K. J. R. , Taylor P. D. P.
Published: April 2010

The Commission’s Subcommittee for the Isotopic Composition of the Elements has carried out its biennial review of isotopic compositions, as determined by mass spectrometry and other relevant methods. This involves a critical evaluation of the published literature, element by element, and forms the basis of the Table of Isotopic Compositions of the Elements as Determined by Mass Spectrometry presented here. New guidelines have been used to arrive at the uncertainties on the isotopic abundances and there are numerous changes to the table since it was last published in 1991. Atomic Weights calculated from this table are consistent with Ar(E) values listed in the Table of Standard Atomic Weights 1997.
Revealing a core signaling regulatory mechanism for pluripotent stem cell survival and self-renewal by small molecules
Authors: Xu Yue , Zhu Xiuwen , Hahm Heung Sik , Wei Wanguo , Hao Ergeng , Hayek Alberto , Ding Sheng
Published: April 2010

Using a high-throughput chemical screen, we identified two small molecules that enhance the survival of human embryonic stem cells (hESCs). By characterizing their mechanisms of action, we discovered an essential role of E-cadherin signaling for ESC survival. Specifically, we showed that the primary cause of hESC death following enzymatic dissociation comes from an irreparable disruption of E-cadherin signaling, which then leads to a fatal perturbation of integrin signaling. Furthermore, we found that stability of E-cadherin and the resulting survival of ESCs were controlled by specific growth factor signaling. Finally, we generated mESC-like hESCs by culturing them in mESC conditions. And these converted hESCs rely more on E-cadherin signaling and significantly less on integrin signaling. Our data suggest that differential usage of cell adhesion systems by ESCs to maintain self-renewal may explain their profound differences in terms of morphology, growth factor requirement, and sensitivity to enzymatic cell dissociation.
The representation of refugees, asylum seekers and immigrants in British newspapers
Authors: KhosraviNik Majid
Published: April 2010

The paper is a CDA investigation on discursive strategies employed by various British newspapers between 1996–2006 in the ways they represent refugees, asylum seekers and immigrants. The period covers several world events which have impacted such representation, creating a large number of articles on and/or about these groups. A combination of quantitative and qualitative down-sampling technique is then devised to restrict the number of articles to a sensitive sample which takes into account the newspapers’ ideological stands; conservative/liberal, their types; quality/tabloid and the relevant world events. The paper discusses some of the salient issues in the ways these groups of people are represented in British newspapers during these 10 years and shows that despite differences — arising from differences in ideological viewpoints and their types — in some important ways all the newspapers contribute to construct refugees, asylum seekers and immigrants in similar ways.
Experts in political communication
Authors: Horsbøl Anders
Published: April 2010

A central journalistic counterstrategy to the communicative ‘professionalization’ of politics consists in a use of political communication experts who comment on political moves and analyse the strategies behind them. This study investigates how the media uses political communication experts in prime time news programmes from the 2005 parliamentary election campaign in Denmark. To this aim, the knowledge positions ascribed to the experts as well as the articulation of the expert voice with the news genre is analysed. Furthermore, the qualitative analysis is combined with quantitative data on the amount of political communication experts and their professional background. The study situates the analysis within a public sphere perspective on the power relations between politics and media, and discusses implications of the findings for a well functioning public sphere.
The ideal of non-coherence in the World Bank’s social capital reforms
Authors: Weltman David , Upchurch Martin
Published: April 2010

This paper presents an analysis of a World Bank document representing a version of the new “Social Capital” approach of International Financial Institutions (IFIs). This stance involves a rhetorical reorientation away from a much criticized unilateral approach to the poor indebted countries and to a more bi-lateral and participatory attitude. Analysis suggests that this “post-ideological” posture is reflected in the text in the form of a copious rhetoric of “complex differentiation”. This consists of characterizing the world in the abstract terms of multiple independent factors which work against any more coherent picture of the historical process and its contradictions. While such formal elements appear to be conditional on and anchored in concrete content, they are shown in fact to reflect the negation of such content (and thus coherence). In this way, an apparently limitless proliferation of free-floating isolated elements substitutes for faithful representation of the underlying social cleavages. The implications of the analysis for contrasting conceptualizations of abstraction in texts, as well as for the notion of utopian discourse, are critically discussed.
Ahmadinejad’s letter to Bush opens dialogue in Middle Eastern rhetorical style
Authors: Stokes Karina
Published: April 2010

Understanding how Middle Eastern rhetoric differs from Western communication can aid in deciphering diplomatic correspondence like the 2006 letter from President Ahmadinejad of Iran. Failure to understand such communications and respond appropriately may result in missed opportunities to avert hostilities or establish effective rapport with other nations. Success in grasping the intent of Iran’s diplomatic overture can provide a basis for creating a response that expresses American sentiments in a way that can be seen as intelligent and appropriate by Middle Eastern recipients. Such correspondence could entail establishing a respectable ethos, arranging content as expected, and emphasizing common values. Knowledge of the Middle Eastern rhetorical tradition can inform a viable understanding for diplomatic correspondence.
Debating the EU Constitution in France
Authors: Koukoutsaki-Monnier Angeliki
Published: April 2010

This paper focuses on the argumentative approaches and the rhetorical strategies employed by political actors in France in favour of or against the EU Constitutional Treaty (TCE), as they appeared in four French daily newspapers,Le Monde,Le Figaro,LibérationandAujourd’hui en France(national edition ofLe Parisien), before the 29th of May 2005 referendum. In a qualitative discourse analysis and with the aid of argumentation theories and political communication approaches, the study investigates how the European Union’s Constitution, identity and future were represented and discussed by French political actors through the media in their effort to obtain public adherence before the referendum. Inevitably, the role of the media and the mediation process in the construction and transcription of the political discourse is also discussed.
Language planning and language-in-education policy in Iran
Authors: Hayati A. Majid , Mashhadi Amir
Published: April 2010

This paper explores the effects of different political ideologies on language, using as examples three historical stages and three political periods in the history of Iran, and the differing policies adopted in these eras concerning language and language education. Over the years, political ideologies have served as a barrier as well as a contributor to language use (whether first or foreign) and to language teaching. The paper then turns to explore local language policies and the status of the Persian language in the modern era, focusing particularly on foreign language teaching policies after the Islamic revolution and their implications for teaching and learning activities and practices in Iran’s educational system. Finally, using several Iranian political periods as an example, this study demonstrates how globalization has influenced the teaching of foreign languages, especially English.
Las representaciones ideológicas del lenguaje
Authors: Narvaja de Arnoux Elvira , del Valle José
Published: April 2010

En este artículo, los editores definen las ideologías lingüísticas y las sitúan en relación con las distintas disciplinas que se han ocupado del estudio contextual del lenguaje (sociolingüística, sociología del lenguaje, antropología lingüística y glotopolítica). Ilustran la aplicación de esta categoría atendiendo a las representaciones ideológicas del español –y otras lenguas como el inglés o el portugués– que han surgido en distintos procesos de integración regional tales como la creación de MERCOSUR o la promoción de la Comunidad Iberoamericana de Naciones. Finalmente, presentan los artículos incluidos en este número especial.
Language policy and the drawing of social boundaries
Authors: DuBord Elise
Published: April 2010

Educational institutions developed in Tucson, Arizona in the last quarter of the nineteenth century, during a critical time in cultural and political shifts of power between Anglo and Mexican elites in Southwestern United States. My qualitative analysis reconstructs language policies in the incipient educational system in Territorial Tucson. This article examines official and unofficial language policies in both public and private schools in Tucson that reflected this accommodation of power and the negotiation of a new racial hierarchy in the context of westward expansion. I argue that the private schools Mexican elites founded in this period maintained bilingual instruction and promoted biliteracy as a means of racially and linguistically distancing themselves from Anglos, Indians and Mexicans from lower socioeconomic classes in public schools.
Ideologías lingüísticas en el Nuevo México territorial
Authors: Fernández-Gibert Arturo
Published: April 2010

De entre todos los territorios anexados por Estados Unidos en detrimento de México en 1848, Nuevo México era el que tenía una población hispana más enraizada en una larga y rica tradición que se remonta a finales del siglo XVI. Hasta 1912, cuando el territorio de Nuevo México entró a formar parte de la Unión americana, los neomexicanos vivieron más de medio siglo resistiendo una aculturación a la inmigrante sociedad angloamericana y al mismo tiempo practicando en las últimas décadas de ese periodo el ejercicio de su autorrepresentación a través de una nueva cultura de la letra impresa que formó una comunidad lectora en español hasta bien entrado el siglo XX. En este trabajo, basado en textos impresos a lo largo de más de veinte años en el semanario La voz del pueblo (1890–1912) publicado en Las Vegas, se analizarán las controvertidas ideologías lingüísticas en las que diversos grupos sociales y políticos neomexicanos promovieron el aprendizaje del inglés para las nuevas generaciones, la lengua nacional, a la vez que defendieron la preservación del español, la lengua ancestral de los neomexicanos desde hacía tres siglos. Las herramientas metodológicas serán: (1) un estudio sociodemográfico que permita seguir la transformación de la población del territorio en este período crítico y nos ayude a entender la situación de conocimiento y uso del español y del inglés por parte de los neomexicanos de la época; (2) un estudio etnohistórico que nos acerque al fenómeno de la cultura de la letra impresa, la producción de su discurso y la formación de una comunidad lectora; (3) un estudio sociolingüístico que nos acerque a la comunidad lingüística neomexicana en su contexto social y político y, (4) una exploración de la formación de ideologías lingüísticas relacionadas con la identidad y la lengua por parte de los actores sociopolíticos del territorio, que nos permita descubrir el proceso de producción e institucionalización de esas ideologías lingüísticas en Nuevo México en vísperas de su plena incorporación a los Estados Unidos.
Poderes de la literatura
Authors: Bentivegna Diego
Published: April 2010

En este artículo indagamos parte de las disputas y los conflictos en torno a la definición de una literatura nacional, legitimada por su circulación en el sistema escolar, en la Argentina de fines del siglo XIX y comienzos del siglo XX. Nos centramos para ello en una serie de intervenciones críticas de dos intelectuales-pedagogos especialmente influyentes en la configuración institucional de la literatura argentina: Calixto Oyuela y Ricardo Rojas. Pondremos especial énfasis en las articulaciones que ambos autores proponen entre lengua y literatura nacional y en el debate que plantean en torno a la existencia al estatuto literario del Martín Fierro, de José Hernández, y a la existencia de una épica argentina. Según sostendremos, tanto en los planteos de Oyuela como en los de Rojas la épica es percibida como una poesía del origen racial de la comunidad nacional sobre cuya base se llevan adelante operaciones de inclusión y exclusión cultural, en el marco del desarrollo de políticas oficiales de unificación simbólica de la nación.