bluuebunny/crossref_metadata_2025 huggingface dataset:
Low index faceting of Pt nanostructures on oxide surface with potential application for fuel cells
Authors: Aurongzeb Deeder
Published: September 2007

Anneal induced faceting of platinum (Pt) thin film is being studied by atomic force microscopy. We find that at 700 °C faceting occurs by first forming percolation clusters. The nanodots form low index facets with the substrate and with various geometric shapes parallel to the substrate. Time dependent coarsening kinetics shows Lifsitz-Slyozov/Wagner type diffusion therefore indicating Oswald ripening. Low index faceting of Pt nanodots is also stepped/faceted showing its potential application for efficient fuel cells.
Broadband near-infrared emission from transparent Ni2+-doped silicate glass ceramics
Authors: Zhou Shifeng , Dong Huafang , Zeng Heping , Wu Botao , Zhu Bin , Yang Hucheng , Xu Shiqing , Wan Zhiyu , Qiu Jianrong
Published: September 2007

Transparent Ni2+-doped MgO–Al2O3–TiO2–SiO2 glass ceramics were prepared, and the optical properties of Ni2+-doped glass ceramics were investigated. Broadband emission centered at 1320nm was observed by 980nm excitation. The longer wavelength luminescence compared with Ni2+-doped Li2O–Ga2O3–SiO2 glass ceramics is ascribed to the low crystal field hold by Ni2+ in MgO–Al2O3–TiO2–SiO2 glass ceramics. The change in optical signals at the telecommunication bands with or without 980nm excitation was also measured when the seed beam passes through the bulk gain host.
Characterization of thermoelectric elements and devices by impedance spectroscopy
Authors: Downey Adam D. , Hogan Timothy P. , Cook Bruce
Published: September 2007

This article describes a new measurement technique that utilizes impedance spectroscopy for the characterization of thermoelectric materials and devices. Two circuit models were developed and used to help explain the impedance spectroscopy data using transmission line theory and a coupled electrothermal model. Two testing configurations have been investigated including one based on a sinusoidal source (ac lock-in technique) and one based on a pulsed wave source. Methods for reducing the measurement times for this technique are discussed. In addition, the influence of radiation losses on this measurement technique has also been analyzed to further understand the limitations of this technique at higher temperatures.
Compressibility effects on the Rayleigh-Taylor instability of three layers
Authors: Hoshoudy G. A.
Published: September 2007

The influence of the compressibility of a horizontal layer sheet embedded in two semi-infinite layers in the presence of surface tension is investigated. The stability problem for the two interfaces has been formulated. A general dispersion relation valid for all modes of perturbation is derived. The dispersion relation is solved numerically for different values of compressibility, pressure at the two interfaces, and thickness of the intermediate layer. It is found that the growth rates of both interfaces are given as though the interfaces were decoupled. The two modes (growth rates) are dependent on the thickness of the intermediate layer. The effects of compressibility disappear at short-wavelength in the absence of surface tension.
Guided modes and loss in a plasma-filled Bragg waveguide
Authors: Chatterton J. D. , Shohet J. L.
Published: September 2007

The dispersion and radiation loss of propagating modes in a plasma-filled Bragg waveguide are investigated. The Bragg waveguide at a center frequency of 10 GHz is modeled with the transfer-matrix method, which has been used to analyze optical Bragg fibers. We calculate the dispersion and radiation loss of the TE01, TM01, and HE11 modes and show how they vary as a function of plasma density. As the plasma density inside the waveguide increases, the cutoff frequency of each mode increases. An increase in plasma density increases the radiation loss in the TE01 mode while it decreases the radiation loss in the TM01 mode; the effect on the HE11 mode is to increase the radiation loss for frequencies above 10.2 GHz and decrease the radiation loss for frequencies below 10.2 GHz.
Well posedness and smoothing effect of Schrödinger-Poisson equation
Authors: De Leo M. , Rial D.
Published: September 2007

In this work we take under consideration the Cauchy problem for the Schrödinger-Poisson type equation i∂tu=−∂x2u+V(u)u−f(∣u∣2)u, where f represents a local nonlinear interaction (we take into account both attractive and repulsive models) and V is taken as a suitable solution of the Poisson equation V=1∕2∣x∣∗(C−∣u∣2), C∊Cc∞ is the doping profile or impurities. We show that this problem is locally well posed in the weighted Sobolev spaces Hs≔{φ∊Hs(R):∫(1+x2)1∕2∣φ∣2<∞} with s⩾1, which means the local existence, uniqueness, and continuity of the solution with respect to the initial data. Moreover, under suitable assumptions on the local interaction, we show the existence of global solutions. Finally, we establish that for s⩾1 local in time and space, smoothing effects are present in the solution; more precisely, in this problem there is locally a gain of half a derivative.
Plasma of iron powder combustion
Authors: Doroshenko J. , Florko A. , Poletaev N. , Vishnyakov V.
Published: September 2007

The results of experimental study of the thermal plasma formed in the two-phase diffusion flame of a burning iron dust cloud are presented. It has been demonstrated that the particles of iron oxide (magnetite) have sufficient charges to form ordered structures.
Precision thickness and refractive index imaging of molecular films
Authors: Balmer T. E. , Heuberger M.
Published: September 2007

We present an interferometric contrasting technique that allows visualizing the thickness and refractive index of a molecular film being part of an optical multilayer structure (etalon). Small wavelength shifts of the comblike etalon spectrum are transformed into measurable intensity variations using a second reference etalon (optical correlator), illuminated in series. A charge-coupled device camera acting as two-dimensional photometer is utilized to measure the optical spectral correlation (OSC) image. The performance of the here proposed optical spectral correlation method is demonstrated using very thin confined liquid films. We give a detailed signal-to-noise analysis. Subangstrom film thickness resolution is experimentally verified with single exposure images acquired at frame rates comparable to video standards (∼25Hz). Finally, we describe the calibration procedures necessary to obtain an absolute quantification of the OSC image.
Permanent electric dipole moment of molybdenum carbide
Authors: Wang Hailing , Virgo Wilton L. , Chen Jinhai , Steimle Timothy C.
Published: September 2007

High resolution optical spectroscopy has been used to study a molecular beam of molybdenum monocarbide (MoC). The Stark effect of the Re(0) and Qfe(1) branch features of the [18.6]Π13-XΣ−3(0,0) band system of Mo98C were analyzed to determine the permanent electric dipole moments μe of 2.68(2) and 6.07(18)D for the [18.6]Π13(ν=0) and XΣ−3(ν=0) states, respectively. The dipole moments are compared with the experimental value for ruthenium monocarbide [T. C. Steimle et al., J. Chem. Phys. 118, 2620 (2003)] and with theoretical predictions. A molecular orbital correlation diagram is used to interpret the observed and predicted trends of ground state μe values for the 4d-metal monocarbides series.
Pump-probe imaging of femtosecond pulsed laser ablation of silicon with thermally grown oxide films
Authors: McDonald Joel P. , Nees John A. , Yalisove Steve M.
Published: September 2007

Femtosecond pulsed laser ablation of silicon substrates with thin thermally grown oxide films (20–1200 nm) was studied using pump-probe microscopy techniques. Images from both the front and side of the ablation event produced at a laser fluence of 1.3 J/cm2 were obtained, and results from the two imaging geometries were compared yielding the optical properties of the ablated material. Ablation dynamics were studied over the time scale from 0 to 10.35 ns following the onset of ablation, and ablated material velocities ranging from 200±20 to −3010±360 m/s were determined depending on the thermal oxide film thickness.
Effect of halogenation on the shock properties of semicrystalline thermoplastics
Authors: Bourne N. K. , Millett J. C. F. , Brown E. N. , Gray G. T.
Published: September 2007

The high-strain rate response of polymers is a subject that has gathered interest over recent years due to their increasing engineering importance, particularly in the transport industries. This work explores the effect of fluorination upon semicrystalline thermoplastics. Polyethylene, with its simple hydrocarbon chain, is considered; with increasing fluorination of the carbon backbone polyvinylidene difluoride, and then polytetrafluorethylene (PTFE) is also compared. All three show a nonlinear equation of state behavior, which may be related to partial crystallinity. PTFE is shown to have anomalous release speed, which reflects its transformation from phase II to phase III transition at 0.7 GPa. Strength effects show a different ordering of behavior between the three materials. The first results are accountable purely using van der Waals forces between the chains. However, strength effects show the effect of further attractive forces that indicate some tacticity in the material associated with the state behind the shock.
Capacitively coupled radio-frequency hydrogen discharges: The role of kinetics
Authors: Marques L. , Jolly J. , Alves L. L.
Published: September 2007

This paper presents a systematic characterization of capacitively coupled radio-frequency hydrogen discharges, produced within a parallel plate cylindrical setup at different rf applied voltages (Vrf=50–600V), frequencies (f=13.56–40.68MHz), and pressures (p=0.2–1torr). A two-dimensional, time-dependent fluid model for charged particle transport is self-consistently solved coupled to a homogeneous kinetic model for hydrogen, including vibrationally excited molecular species and electronically excited atomic species. Numerical simulations are compared with experimental measurements of various plasma parameters. A good quantitative agreement is found between simulations and experiment for the coupled electrical power and the plasma potential. The model underestimates the values of the electron density, the self-bias potential, and the H(n=1) atom density with respect to measurements, but agrees with experiment when predicting that all these parameters increase with either Vrf, f, or p. The dissociation degree is about 10−3 for the work conditions considered. Simulations adopt a wall recombination probability for H atoms that was experimentally measured, thus accounting for surface modification with discharge operating conditions. Results show the key role played by the atomic wall recombination mechanism in plasma description.
Anatomy of malicious singularities
Authors: Heller Michael , Odrzygóźdź Zdzisław , Pysiak Leszek , Sasin Wiesław
Published: September 2007

As well known, the b boundaries of the closed Friedman world model and of Schwarzschild solution consist of a single point. We study this phenomenon in a broader context of differential and structured spaces. We show that it is an equivalence relation ρ, defined on the Cauchy completed total space E¯ of the frame bundle over a given space-time, that is responsible for this pathology. A singularity is called malicious if the equivalence class [p0] related to the singularity remains in close contact with all other equivalence classes, i.e., if p0∊cl[p] for every p∊E. We formulate conditions for which such a situation occurs. The differential structure of any space-time with malicious singularities consists only of constant functions which means that, from the topological point of view, everything collapses to a single point. It was noncommutative geometry that was especially devised to deal with such situations. A noncommutative algebra on E¯, which turns out to be a von Neumann algebra of random operators, allows us to study probabilistic properties (in a generalized sense) of malicious singularities. Our main result is that, in the noncommutative regime, even the strongest singularities are probabilistically irrelevant.
Quantum bits with Josephson junctions (Review Article)
Authors: Wendin G. , Shumeiko V. S.
Published: September 2007

Recent demonstrations of macroscopic quantum coherence in Josephson junction based electronic circuits have opened an entirely new dimension for research and applications in the established field of Josephson electronics. In this article we discuss basic Josephson circuits for qubit applications, methods of quantum description of these circuits, and circuit solutions for qubit couplings. Principles of manipulation and readout of superconducting qubits are reviewed and illustrated with recent experiments using various qubit types.
Giant super-Poissonian shot noise in spin-polarized SET structures
Authors: Gorelik L. Y. , Kulinich S. I. , Shekhter R. I. , Jonson M. , Vinokur V. M.
Published: September 2007

We study transport of spin-polarized electrons through a magnetic single-electron transistor (SET) in the presence of an external magnetic field. Assuming the SET to have a nanometer-sized central island with a single electron level, we find that the zero-frequency shot noise diverges as the on-dot spin-flip rate goes to zero, provided the source and drain leads are completely polarized in the same direction. We present an analytical expression for the low-frequency super-Poissonian shot noise that allows one to specify the necessary conditions for the experimental observation of the phenomenon.
The unusual properties of anisotropic systems of quasiparticles in superfluid He4
Authors: Adamenko I. N. , Nemchenko K. E. , Slipko V. A. , Wyatt A. F. G.
Published: September 2007

We discuss a number of unusual phenomena discovered recently in anisotropic quasiparticle systems in superfluid He4. These include the creation of high-energy phonons by a pulse of low-energy phonons, the suprathermal distribution of high-energy phonons in long phonon pulses, the mesa shape of the angular distribution of low-energy phonons, and the creation of a “hot line” when two-phonon pulses cross. The thermodynamic properties of anisotropic quasiparticle systems of He II are derived for all degrees of anisotropy.
Extracting ion emission lines from femtosecond-laser plasma x-ray spectra heavily contaminated by spikes
Authors: Gasilov S. V. , Faenov A. Ya. , Pikuz T. A. , Villoresi P. , Poletto L. , Stagira S. , Calegari F. , Vozzi C. , Nisoli M.
Published: September 2007

Nowadays charged-coupled device (CCD) detectors are widely used for the registration of multicharged ions x-ray spectra. These spectra are generated in a plasma during interaction of ultrashort, ultraintense laser pulses with solid targets. Strong parasitic radiation from the plasma affects CCD detectors and contaminates resulting spectra, so that spectral features can be completely covered by noise even during measurements with a very short accumulation time. In this work we propose a “mean to median” (M2M) algorithm for noise suppression in femtosecond laser plasma x-ray spectra. Series of spectra is necessary for the identification of corrupted data points by the developed method. The algorithm was tested with model spectra which reflect main features of experimental data. In practice we used it for extracting information about spectral lines of Ne-like Fe ions and He-like Al ions which allowed us to calculate plasma parameters. It is demonstrated that M2M method is able to clean spectra with more than 10% of corrupted pixels. Fluctuations in intensity of spectral lines induced by laser instability do not affect validity of the proposed method.
Optical method for measuring the azimuthal anchoring strength of liquid crystals using pitch values determined in imperfect samples
Authors: Tang Tsung-Ta , Wu Hsin-Ying , Lin Chia-Jen , Pan Ru-Pin
Published: September 2007

An improved Grandjean–Cano wedge method for measuring the pitch of a chiral nematic liquid crystal is demonstrated. This method is easy to implement and can yield results of high accuracy when it is used for measuring the liquid crystal surface anchoring strength.
Double hydrogenic impurities in double quantum dots
Authors: Wang Xue-Feng , Liu Yong-Hui
Published: September 2007

The ground states and degree of entanglement of double hydrogenic impurities in a pair of vertically stacked InGaAs/GaAs quantum dots are studied with a proposed diagonalization technique. It is found that at short barrier widths, the entanglement is small due to the coupling between the intra- and interdot orbitals. At large barrier widths, large entanglement occurs.
Growth mechanism from nano-ordered clusters to nanocrystals in a deeply undercooled melt of Zr-Ni-Ti metallic glass
Authors: Liu X. J. , Chen G. L. , Hui X. D. , Hou H. Y. , Yao K. F. , Liu C. T.
Published: September 2007

Both experimental studies and molecular dynamics (MD) simulations reveal a unique atomic-scale growth mechanism during crystallization of an amorphous alloy Zr65Ni25Ti10. By using a high-resolution transmission electron microscope incorporated with nanobeam diffraction technique, we have clearly seen imperfect ordered packing of nano-ordered clusters (NOCs) with a size of 1–2 nm embedded in this amorphous material. Under a very large undercooling condition, NOCs essentially act as preexisting nuclei that can grow directly into nanocrystals during annealing treatments. The growth mechanism includes three distinct steps in succession: formation of quasi-ordered structure with one-dimensional (1D) periodicity, and then 2D periodicity, and finally forming 3D nanocrystals. These three growth steps are cross-linked, and atomic movements are also accommodated by a rotation of atomic planes. This growth mechanism is unambiguously verified by MD simulation.
Current-induced mechanical torsion of a magnetic nanowire
Authors: Yu Hao , Liu J.–M.
Published: September 2007

The effect of current-induced mechanical torsion in a ferromagnetic nanowire is investigated. The applied current transfers angular momentums of conductive electrons to the domain wall and leads to elastic rotation of the nanowire, which has the same physical essence as the Einstein–de Haas effect owing to the conservation of angular momentum. The as-induced strain in static state is calculated and the mechanical torsion vibration in the dynamic state may be useful for developing nanomotor devices.
Size quantization in metal films
Authors: Nedorezov S. S.
Published: September 2007

The quantum size effect, predicted by I. M. Lifshits and A. M. Kosevich [Izv. Akad. Nauk SSSR Ser. Fiz. 19, 395 (1955)] has been investigated in many studies. The underlying basis of the analysis of quantum size oscillations of thermodynamics and kinetic characteristics of metal films is the quasiclassical quantization of the momentum component for isotropy model and quantization {S. S. Nedorezov, Zh. Éksp. Teor. Fiz. 51, 868 (1966) [Sov. Phys. JETP 24, 578 (1967)]} of a chord of the constant-energy surface in the case of anisotropy of the energy spectrum. In the given work the research of quantum size levels of energy of electrons in metal films is carried out by the method of J. M. Luttinger and W. Kohn. The exact conditions of size quantization are obtained.
Collective excitations in dynamics of liquids: a “toy” dynamical model for binary mixtures
Authors: Bryk T. , Mryglod I. M.
Published: September 2007

We propose a new “toy” dynamical model that permits us to derive analytical expressions for dispersion of two branches of “bare” propagating collective excitations in binary disordered systems in the whole range of wave numbers. These expressions are used for the analysis of dependence of dispersion curves on mass ratio and concentration at fixed density of the system. An effect of hybridization of two branches is discussed in terms of mode contributions to time correlation functions. This allows us to estimate the regions with dominant types of coherent or partial dynamics.
Effect of inclusion deformation on the magnetoelectric effect of particulate magnetostrictive/piezoelectric composites
Authors: Wong C. K. , Shin F. G.
Published: September 2007

We have investigated the magnetoelectric (ME) properties of particulate composites with magnetostrictive inclusions dispersed in a piezoelectric matrix. A simple model is proposed which includes a rarely discussed contribution from the shape deformation of the inclusion particles due to the magnetostrictive stresses generated under the action of an external magnetic field. The relative significance of this contribution is mainly determined by the ratio of the transverse and longitudinal magnetostrictive responses of the inclusion as well as the flexibility of the piezoelectric matrix phase. This model gives further insight on material selections for designing particulate ME composites.
Correlation between electrical and ellipsometric properties on high-quality epitaxial thin films of the conductive oxide LaNiO3 on STO (001)
Authors: Noun W. , Berini B. , Dumont Y. , Dahoo P. R. , Keller N.
Published: September 2007

Direct current (dc) electrical transport properties (resistivity and Hall) and spectroscopic ellipsometric measurements have been combined to study high-quality epitaxial thin films of LaNiO3 (LNO) on SrTiO3 (001) substrates. Stoichiometry of LaNiO3 films was changed by varying the oxygen partial pressure between 240 and 420 μbar during the growth in a pulsed laser deposition setup. Structural and temperature-dependent transport properties conform to epitaxial LaNiO3. The ellipsometric data, measured in the 350–850 nm spectral range, are adjusted with a dispersion relation of Drude-Lorentz (DL) type. In addition to the Drude term, only one Lorentz oscillator was used in the modeling for consistency with existing density of states calculations. Increasing oxygen pressure does not induce significant variations of the electronic density, the Hall mobility, or the Drude plasma energy. Neither are the pseudo-cubic lattice parameter and the Lorentz oscillator resonance energy significantly modified. Resistivity from dc transport and “optical” resistivity from the DL dispersion relation are found to be in good agreement in the case of epitaxial LNO films, giving an elegant way to control the electrical properties of the LaNiO3 conductive oxide thin films in situ by the spectroscopic ellipsometry technique during growth.
Effect of Au drops on the phase velocity dispersion of Rayleigh waves in Si crystals
Authors: Tarasenko A. , Bohac P. , Fedorovich R. D. , Jastrabik L. , Picek R.
Published: September 2007

Effect of Au drops on the phase velocity dispersion of Rayleigh waves in Si crystals We have measured the phase velocity dispersion of the Rayleigh waves on a (001)Si surface covered by a thin island film of Au. The effect of the film on the propagation of the acoustic surface waves is explained using a model of discontinuous film having zero elastic moduli. The experimental data are in good coincidence with the proposed model.
In situ visualization of domain kinetics in flux grown KTiOPO4 by digital holography
Authors: Canalias C. , Pasiskevicius V. , Laurell F. , Grilli S. , Ferraro P. , De Natale P.
Published: September 2007

The fast dynamic evolution of ferroelectric domains during electric field poling in flux grown KTiOPO4 crystals was investigated online by a digital holography based technique. The dependence of the ferroelectric domain kinetics on the electric field temporal wave form and poling history was studied. High-speed imaging by means of a complementary metal-oxide-semiconductor image sensor camera allowed in situ measurement of the domain wall propagation speed under different poling conditions. The results also give evidence of the strong influence of the dielectric surface layer in this material.
High-order harmonic generation from plasma plume pumped by 400nm wavelength laser
Authors: Ganeev Rashid A. , Elouga Bom Luc B. , Ozaki Tsuneyuki
Published: September 2007

The authors present their study on high-order harmonic generation pumped by 400nm wavelength laser from plasma plumes produced on the surfaces of various solid-state targets. The maximum harmonic cutoff was observed for Be plasma (31st harmonic, λ=12.9nm). They compared these results with harmonic generation pumped by 800nm wavelength laser. The authors demonstrated single harmonic enhancement for Cr, Sn, Sb, and Mn plasmas. They also studied the use of varying the chirp of the pump laser to control the enhancement of single harmonics within the plateau.
Growth temperature dependence of Mn∕GaAs surfaces and interfaces
Authors: Hilton J. L. , Schultz B. D. , Palmstrøm C. J.
Published: September 2007

In situ x-ray photoelectron spectroscopy and scanning tunneling microscopy were combined to examine the formation of the reacted region at the Mn∕GaAs(001) interface during deposition. Thin films of Mn were grown on GaAs c(4×4) surfaces by molecular beam epitaxy at substrate temperatures of 40, 95, and 250°C. The attenuations of the Ga and As photoemission peak intensities as a function of Mn deposition indicate the formation of a reacted layer at the interface with an average composition of Mn0.6Ga0.2As0.2, and submonolayer coverages of As were found to segregate to the sample surface independent of the growth temperature. The extent of the Mn–Ga–As interfacial reactions that occur during the growth of Mn on GaAs strongly depends upon the growth temperature. At growth temperatures of 95°C and below, the interfacial reacted layer reaches a thickness that is sufficient to limit any additional diffusion of Mn into the GaAs. During growth at 250°C the rate of diffusion is higher and the interfacial reacted layer continues to increase in thickness as the rate of diffusion remains similar to the growth rate for depositions ranging up to hundreds of angstroms.
In situ health monitoring and repair in composites using carbon nanotube additives
Authors: Zhang W. , Sakalkar V. , Koratkar N.
Published: September 2007

The authors demonstrate a simple, effective and real-time diagnostic, and repair technique featuring electrically conductive carbon nanotube additives that are infiltrated into the host structure. They show that by monitoring volume and through-thickness resistance, one can determine the extent and propagation of fatigue-induced damage such as crack and delamination growth in the vicinity of stress concentrations. The conductive nanotube network also provides opportunities to repair damage by enabling fast heating of the crack interfaces; the authors show up to 70% recovery of the strength of the undamaged composite. These advances could result in enhanced safety, reliability, and service life for polymer composites that are used in engineering applications.
Nonequilibrium statistical operators for systems with finite lifetime
Authors: Ryazanov V. V.
Published: September 2007

A family of nonequilibrium statistical operators (NSO) is introduced which differ by the system lifetime distribution over which the quasiequilibrium (relevant) distribution is averaged. This changes the form of the source in the Liouville equation, as well as the expressions for the kinetic coefficients, average fluxes, and kinetic equations obtained with use of NSO. The difference from the Zubarev form of NSO is of the order of the reciprocal lifetime of system.
Fine structure of critical opalescence spectra
Authors: Sushko M. Ya.
Published: September 2007

The effect of the 1.5-scattering mechanism on the time and temperature behavior of the electric field autocorrelation function for the light wave scattered from fluids has been studied for the case where the order-parameter fluctuations obey the diffusion-like kinetics with spatially-dependent kinetic coefficient. The leading contributions to the relevant static correlation functions of the order-parameter fluctuations were obtained by using the Ginzburg-Landau model with a cubic term, and then evaluated with the use of the Gaussian uncoupling for many-point correlation functions and the Ornstein-Zernicke form for the pair correlation function. It is shown that the presence of the 1.5-scattering effects in the overall scattering pattern may be detected in the form of a small but noticeable deviation from exponential decay of the total electric field autocorrelation function registered experimentally near the critical point. Obtained with the standard methods of analysis, the effective half-width of the corresponding spectrum can reveal a stronger temperature dependence and a multiplicative renormalization as compared to the half-width of the spectrum of the pair correlator.
Current-induced domain wall depinning and magnetoresistance in La0.7Sr0.3MnO3 planar spin valves
Authors: Ruotolo A. , Oropallo A. , Miletto Granozio F. , Pepe G. P. , Perna P. , di Uccio U. Scotti , Pullini D.
Published: September 2007

The authors have performed experiments on current-induced domain wall (DW) displacement in La0.7Sr0.3MnO3 nanostructures patterned by gallium (Ga) focused-ion-beam milling. A dc current is found to assist or hinder, according to polarity, an external magnetic field in the depinning of a DW trapped in a nanoconstriction. For large enough currents, the DW depinning occurs in the absence of external magnetic field. The depinning current depends on the transverse anisotropy constant of the region toward which the DW is displaced.
Atomic force microscopy of protein films and crystals
Authors: Pechkova Eugenia , Sartore Marco , Giacomelli Luca , Nicolini Claudio
Published: September 2007

A customized atomic force microscopy (AFM) instrument optimized for imaging protein crystals in solution is described. The device was tested on crystals and Langmuir-Blodgett (LB) films of two proteins with quite different molecular weights. This approach enables the periodicity and morphology of crystals to be studied in their mother liquid, thereby preserving the native periodic protein crystal structure, which is typically destroyed by drying. Moreover, the instrument appears to distinguish protein crystals from salt crystals, which under the optical microscope are frequently quite similar, the difference between them often being revealed only during x-ray analysis. AFM estimates of the packing, order, and morphology of the given single proteins appear quite similar in the LB thin film and in the crystals, which means that routine crystal measurements can be performed at high resolution. The AFM consists of a custom-built measuring head and a homemade flexible SPM controller which can drive the head for contact, noncontact and spectroscopy modes, thus providing the user with a high degree of customization for crystal measurement.
Narrow-band detection of propagating coherent acoustic phonons in piezoelectric InGaN∕GaN multiple-quantum wells
Authors: Chen Cheng-Ying , Wen Yu-Chieh , Chen Hung-Ping , Liu Tzu-Ming , Pan Chang-Chi , Chyi Jen-Inn , Sun Chi-Kuang
Published: September 2007

The authors demonstrated that the piezoelectric superlattice, can serve as narrow-band detectors for propagating coherent longitudinal acoustic phonons at multiple frequencies corresponding to the spatial frequency of the superlattice and its higher harmonics, and its detection bandwidth is determined by the total structure width. By optically exciting a broadband propagating longitudinal acoustic pulse from a thin Ni film, the authors studied the acoustic spectral sensitivity function of a ten-period In0.12Ga0.88N∕GaN multiple quantum well. Because the barriers (19nm) and wells (3.6nm) are of different widths, the second detection band, corresponding to the second harmonic of the fundamental frequency, can be resolved.
Controlled modification of erbium lifetime in silicon dioxide with metallic overlayers
Authors: Bao Jiming , Yu Nanfang , Capasso Federico , Mates Thomas , Troccoli Mariano , Belyanin Alexey
Published: September 2007

The authors report systematic measurements of the lifetime of the 1.54μm transition of erbium implanted at different energies in SiO2 films coated with different metals (titanium and chromium). The lifetime shows a strong reduction (up to a factor of 20) with decreasing distance between the erbium and the metal overlay. Their experiments combined with rigorous theoretical modeling demonstrate that a high degree of control over the radiative properties of erbium can be achieved in erbium-implanted materials in a wide range of implantation energies.
Continuous measurements of bronchial exposure induced by radon decay products during inhalation
Authors: Iwaoka Kazuki , Tokonami Shinji , Yonehara Hidenori , Ishikawa Tetsuo , Doi Masahiro , Kobayashi Yosuke , Yatabe Yoshinori , Takahashi Hiroyuki , Yamada Yuji
Published: September 2007

The deposition of radon decay products is not equal in each of the respiratory regions and as the presence of radon has been linked with an increase in lung cancer risk, it is important to calculate the deposition of radon decay products in each of the respiratory regions. Recently, many studies on the deposition of radon in respiratory regions have been simulated using wire screens. The systems and equipment used in those studies are not suitable for field measurements as their dimensions are relatively massive, nor can they measure continuously. We developed a continuous bronchial dosimeter (CBD) which is suitable for field measurements. It was designed with specifications that allow it to be remain compact. The CBD simulates the deposition of radon decay products in the different respiratory regions by the use of a combination of wire screens. Deposition in the simulated regions of the lung can be continuously estimated in various environments. The ratio of activities deposited in a simulated nasal cavity (N) and tracheobronchial (TB) regions was calculated from the results of simultaneous measurements using CBD-R (reference), CBD-N (nasal), and CBD-TB (tracheobronchial) measurement units. After aerosols were injected into the radon chamber, the ratio of N and TB depositions decreased. This results indicate that the CBD gave a good response to changes in the environment. It was found that the ratio of N and TB deposition also varied with time in each actual environment.
Role of long range ferromagnetic order in the electronic structure of Sr1−xCaxRuO3
Authors: Singh Ravi Shankar , Medicherla V. R. R. , Maiti Kalobaran
Published: September 2007

We investigate the role of long range ferromagnetic order in the electronic structure of Sr1−xCaxRuO3 using high resolution photoemission spectroscopy. SrRuO3 is a ferromagnetic metal but isostructural, isoelectronic CaRuO3 is an enhanced paramagnet. Surface spectra of CaRuO3 exhibit temperature induced modifications. This is not significant in other compositions. This may be attributed to the structural changes observed in previous studies. Interestingly, the bulk spectra reveal unusual spectral changes exhibiting a large decrease in the coherent feature intensity corresponding to only ferromagnetic samples, although the Ru moment is very similar in all compositions.
Fluorine counter doping effect in B-doped Si
Authors: Impellizzeri G. , Mirabella S. , Piro A. M. , Grimaldi M. G. , Priolo F. , Giannazzo F. , Raineri V. , Napolitani E. , Carnera A.
Published: September 2007

We investigated the effect of F on the electrical activity of B-doped junctions in preamorphized Si. It is shown that while the carrier dose introduced by B is reduced in the presence of F, no indication of B–F complexes formation can be found and B maintains its full substitutionality. Investigations on F-enriched crystalline Si demonstrated and quantified the n-type doping of F. These results clarify that the loss of holes in junctions coimplanted with B and F is not due to a chemical interaction between B and F, but simply to a dopant compensation effect.
A quasidistributed fiber optic sensor for solute concentration measurement based on Fresnel reflection
Authors: Wu Yi Ting , Huang Xu Guang , Su Hui
Published: September 2007

A quasidistributed fiber sensor for solute concentration measurement based on Fresnel reflection from fiber tips and the interrogation of an arrayed waveguide grating is presented. Thin-film filters are utilized to achieve the possibility of wavelength-division-multiplexing distributed sensing. The experimental results can be fitted to a linear equation very well, with a value of R2 larger than 0.993. The quasidistributed sensor exhibits a capability for real-time, remote measurement of concentrations with high precision, and offers a solid structure, low cost, and easy implementation.
Submicron active-passive integration with position and number controlled InAs∕InP (100) quantum dots (1.55μm wavelength region) by selective-area growth
Authors: Zhou D. , Anantathanasarn S. , van Veldhoven P. J. , van Otten F. W. M. , Eijkemans T. J. , de Vries T. , Smalbrugge E. , Nötzel R.
Published: September 2007

The authors report lateral positioning and number control of InAs quantum dots (QDs) on truncated InP (100) pyramids by selective-area metal organic vapor-phase epitaxy. With reducing QD number, sharp emission peaks are observed from individual and single QDs with wavelength tuned into the 1.55μm telecom region by insertion of ultrathin GaAs interlayers beneath the QDs. Regrowth of a passive waveguide structure around the pyramids establishes submicrometer-scale active-passive integration for efficient microcavity QD nanolasers and single photon sources.
The idiomatic expression of incoherent discourse: “can’t make head nor tail”
Authors: García Jurado Francisco , Maíz Arévalo Carmen
Published: September 2007

This paper analyses the idiomatic expression “can’t make head nor tail” both in Latin and English. The cognitive analysis of these expressions (syntactic variations and use of other body parts in English), their content (these expressions involve spatial and ontological metaphoric schemata to indicate the abstract idea of coherence, generally referred to discourse) and their context (the tone is quite often colloquial) together with the study of the differences and common aspects between the Latin expression and the English one will allow us to inquire into the origin and development of each expression.
On the reality of constructions
Authors: Valenzuela Javier , Hilferty Joseph , Garachana-Camarero Mar
Published: September 2007

In the present paper, we adduce further evidence for the reality of grammatical constructions by focusing on a highly idiosyncratic configuration from Spanish, which we call the reduplicative-topic construction. This construction is a productive syntactic pattern that functions as a “constructional hedge”. The grammatical behaviors of this construction cannot be captured by syntactocentric approaches to grammar. Instead, co-ocurring multiple constraints must be taken into account, including phonological (intonation and rhythm), morphosyntactic and semantic factors.

The thrust of our argument is that only a constructional approach can explain the facts needed to characterize this grammatical pattern. We conclude the paper by considering the implications of the constructional approach to syntax for linguistic theory.
On Existential Bare Plural ‘Subjects’
Authors: Kallulli Dalina
Published: September 2007

Drawing on Strawson’s (1971) definition of the subject as performing the function of identifying the object of the speaker’s assertion and of the predicate as applying to this object without having to identify it, this article argues that being a predicate and being (part of) the focus are two ways of talking about one and the same thing, namely assertion, and not identification or presupposition. Assuming that syntax and semantics are isomorphic, the most far-reaching consequence of this view and the central claim that I make is that there are no existential bare plural subjects. What is generally and a priori taken to be an existential bare plural subject is a (wh-moved) predicate nominal. The genuine external argument in sentences with existential bare plurals in what appears to be the subject position is in fact the Davidsonian event argument. Consequently, the Extended Projection Principle (EPP) should be defined as a requirement on predication. The syntax-semantics isomorphism is emphasized as part of an attempt to show that syntactically, generic and existential bare plurals differ with respect to the D-feature: while generic bare plurals are DPs with a morphologically null D, existential bare plurals, like bare singulars, are NPs altogether lacking a D-projection.
Accounting for English article interpretation by L2 speakers
Authors: Hawkins Roger , Al-Eid Saleh , Almahboob Ibrahim , Athanasopoulos Panos , Chaengchenkit Rangsiya , Hu James , Rezai Mohammad , Jaensch Carol , Jeon Yunju , Jiang Amy , Leung Yan-kit Ingrid , Matsunaga Keiko , Ortega Martha , Sarko Ghisseh , Snape Neal , Velasco-Zárate Kalinka
Published: September 2007

Ionin, Ko and Wexler (2004a) have shown that L2 speakers of English whose L1’s lack articles (Russian and Korean) appear to fluctuate in their interpretation of the and a, allowing them to encode either definiteness or specificity. They argue that these are two options of an Article Choice Parameter offered by Universal Grammar, and that the Russian and Korean speakers fluctuate between them when they are acquiring English. In the present study it is shown that a similar pattern can be observed in L2 speakers of English whose L1 is Japanese (also a language that lacks articles) but not in speakers whose L1 is Greek, a language with articles that encode definiteness like English. It is also shown that while group results for the Japanese speakers suggest fluctuation, individual results do not. It is argued that an account can be given of both cases which does not require appeal either to an Article Choice Parameter or to the concept of ‘fluctuation’. The alternative proposal made here is consistent with Universal Grammar, and follows from an organisation of the grammar where phonological exponents are separated from the lexical items manipulated by syntactic computations, as in Distributed Morphology. It is suggested that a descriptively adequate account which avoids a construction-specific parameter like the Article Choice Parameter and departure from the normal assumptions of UG represented by fluctuation should be preferred.
Some characteristics of expository writing in Cameroon English
Authors: Nkemleke Daniel
Published: September 2007

One of the major characteristics of English in non-native settings is that it exists alongside indigenous languages and most people who study English here come to the language classroom with knowledge of at least an L1. Because the rhetorical structure of the L1 of these learners is not the same as that of English, what is written in these settings often exhibits features that do not meet the expectation of a typical western mind. This study analyses the structural configuration and some syntactic features that characterise students’ essays in a formal academic situation in Cameroon. The corpus is composed of 104 essays written by two batches of students (2002/2003, 2003/2004 academic years) in the department of English of the Ecole Normale Supérieure Yaoundé. Findings reveal that the structure of most essays examined does not follow the strict logical sequence that is characteristic of the typical English essay. And this may well reflect the narrative style that is foreign to the English native speaker. Again, there is a general tendency of register “mixing” in most of the essays. The article concludes that expository writing in Cameroon may well constitute a fruitful area of research into aspects of “nativization” of cohesion and rhetorical strategies of English in the “Outer Circle”.
Cameroon Pidgin and Cameroon English at a confluence
Authors: Ngefac Aloysius , Sala Bonaventure M.
Published: September 2007

The paper argues that Cameroon Pidgin, a simplified language that displayed a unique peculiarity in the yesteryears, is now giving up most of its phonological peculiarities and embracing those of the variety of English spoken in Cameroon. An analysis of the speech of 150 educated Cameroon Pidgin speakers, randomly selected, shows that such phonological processes as heavy infiltration of sounds from indigenous Cameroonian languages, rampant consonant cluster simplification through vowel epenthesis and other segmental peculiarities which characterized Cameroon Pidgin by 1960, as depicted in Schneider (1960), are by far less perceivable in current Cameroon Pidgin usage. It is demonstrated that the feeling that Pidgin is an inferior language has caused Cameroon Pidgin speakers to opt for the “modernization” of the language using English language canons, instead of preserving the state of the language as it was in the yesteryears. It is therefore predicted that Cameroon Pidgin and Cameroon English will sooner or later be in a continuum.
The vowels of Brunei English
Authors: Sharbawi Salbrina
Published: September 2007

This paper provides an acoustic description of the vowels of Brunei English (BrunE). Ten female BrunE speakers were recorded reading The North Wind and the Sun (NWS) passage. The formant values of the eleven monophthong vowels and the rate of change (ROC) of the diphthong /eI/ were measured and compared with the data of seven British English (BrE) speakers and also the results of similar studies on Singapore English (SgE). It was found that BrunE shares some common features with SgE as both groups do not distinguish between /i˜/ and /I/, /e/ and /æ/, and /f˜/ and /#/. The high back vowels of BrunE, however, are unlike the SgE vowels. Whereas in SgE /u˜/ and /~/ are fully back, in BrunE these two vowels are fronted, so they are similar to the vowels of the BrE speakers. The data also shows that BrunE /f˜/ is more open and less back than BrE /f˜/. For /eI/, the average ROC for Bruneian speakers is considerably less negative than that for British speakers, which indicates that in BrunE, just as in SgE, this vowel is less diphthongal than its counterpart in BrE.
Are determiners heads?
Authors: Hudson Richard A.
Published: September 2007

The paper focuses on the relation between the determiner (D) and the common noun (N) in a noun phrase (NP). Four facts show that D depends on N: only N is relevant to whether NP can be used as an adjunct; possessive determiners are similar to clearly dependent possessives e.g. in Dutch and German; N decides whether or not D is obligatory; and in English only one D is possible per N. Three other facts show the converse, that N depends on D: in many languages D sometimes fuses with a preceding preposition (e.g. French de le = du; English for each = per); D decides whether or not N is obligatory; the ellipsis of N is a regular example of dependent ellipsis. Therefore D and N are mutually dependent, a relation which requires the structural flexibility offered by Word Grammar. This does not mean that NP has two heads, but rather that either D or N may be the head.
Noun phrases without nouns
Authors: Dryer Matthew S.
Published: September 2007

In this paper, I investigate the theoretical status of noun phrases without nouns, i.e. noun phrases that do not contain a noun or pronoun, but only words that otherwise occur as modifiers of nouns. I investigate six possible analyses for such noun phrases: (1) that they are elliptical, (2) that the apparent modifiers are nouns, (3) that the apparent modifiers are heads, (4) that the determiner is the head, (5) that they are headless, (6) that all noun phrases are headless. Although the answers vary depending on the language investigated, I argue that the last hypothesis is generally the most plausible one.