bluuebunny/crossref_metadata_2025 huggingface dataset:
Gesture and Motor Skill in Relation to Language in Children With Language Impairment
Authors: Iverson Jana M. , Braddock Barbara A.
Published: August 2010

Purpose

To examine gesture and motor abilities in relation to language in children with language impairment (LI).

Method

Eleven children with LI (aged 2;7 to 6;1 [years;months]) and 16 typically developing (TD) children of similar chronological ages completed 2 picture narration tasks, and their language (rate of verbal utterances, mean length of utterance, and number of different words) and gestures (coded for type, co-occurrence with language, and informational relationship to language) were examined. Fine and gross motor items from the Battelle Developmental Screening Inventory (J. Newborg, J. R. Stock, L. Wneck, J. Guidubaldi, & J. Suinick, 1994) and the Child Development Inventory (H. R. Ireton, 1992) were administered.

Results

Relative to TD peers, children with LI used gestures at a higher rate and produced greater proportions of gesture-only communications, conventional gestures, and gestures that added unique information to co-occurring language. However, they performed more poorly on measures of fine and gross motor abilities. Regression analyses indicated that within the LI but not the TD group, poorer expressive language was related to more frequent gesture production.

Conclusions

When language is impaired, difficulties are also apparent in motor abilities, but gesture assumes a compensatory role. These findings underscore the utility of including spontaneous gesture and motor abilities in clinical assessment of and intervention for preschool children with language concerns.
Predictors of Morphosyntactic Growth in Typically Developing Toddlers: Contributions of Parent Input and Child Sex
Authors: Hadley Pamela A. , Rispoli Matthew , Fitzgerald Colleen , Bahnsen Alison
Published: August 2010

Purpose

Theories of morphosyntactic development must account for between-child differences in morphosyntactic growth rates. This study extends Legate and Yang’s (2007) theoretically motivated cross-linguistic approach to determine if variation in properties of parent input accounts for differences in the growth of tense productivity.

Method

Fifteen toddlers (and parents) participated. None were producing tense morphemes productively at 21 months. Two dependent measures of morphosyntactic growth between 21 and 30 months were used: empirical Bayes linear coefficients at 21 months and predicted productivity scores at 30 months. Predictor variables included child sex, vocabulary, and mean length of utterance as well as 4 measures of parent language input at 21 months.

Results

Input informativeness for tense was the most consistent predictor of morphosyntactic growth, explaining 28.3% of the unique variance in children’s linear growth coefficients at 21 months and 23.0% of the unique variance in predicted tense productivity scores at 30 months. General input measures were unrelated. Child sex explained an additional 24.7% of the variance in early linear growth. Child vocabulary at 21 months did not explain a significant proportion of unique variance.

Conclusion

The findings provide evidence that
input informativeness,
an abstract and distributed property of input, contributes to morphosyntactic growth.
The Primacy of Priming in Grammatical Learning and Intervention: A Tutorial
Authors: Leonard Laurence B.
Published: August 2010

Purpose

The author presents a tutorial on structural priming and its relevance to the study of grammatical development and language intervention.

Method

The findings from structural priming studies are examined from the standpoint of the types of changes that occur in participants' language use, the contexts in which these changes occur, and the effects of these changes on participants' language knowledge. Details of children’s grammatical development and language intervention are then considered in light of these findings.

Results

Evidence from the structural priming literature provides insight into the transition from early conservative grammatical use to broader abstract grammatical use in young children, and suggests ways in which language intervention activities can be modified to promote greater grammatical change in children with language impairments.

Conclusions

Structural priming is not divorced from everyday language use. Evidence from priming research can be put to use in the study of children’s grammatical development and in shaping the methods that are used to facilitate children’s grammatical abilities.
The influence of Pt redistribution on Ni1−xPtxSi growth properties
Authors: Demeulemeester J. , Smeets D. , Comrie C. M. , Van Bockstael C. , Knaepen W. , Detavernier C. , Temst K. , Vantomme A.
Published: August 2010

We have studied the influence of Pt on the growth of Ni silicide thin films by examining the Pt redistribution during silicide growth. Three different initial Pt configurations were investigated, i.e., a Pt alloy (Ni+Pt/⟨Si⟩), a Pt capping layer (Pt/Ni/⟨Si⟩) and a Pt interlayer (Ni/Pt/⟨Si⟩), all containing 7 at. % Pt relative to the Ni content. The Pt redistribution was probed using in situ real-time Rutherford backscattering spectrometry (RBS) whereas the phase sequence was monitored during the solid phase reaction (SPR) using in situ real-time x-ray diffraction. We found that the capping layer and alloy exhibit a SPR comparable to the pure Ni/⟨Si⟩ system, whereas Pt added as an interlayer has a much more drastic influence on the Ni silicide phase sequence. Nevertheless, for all initial sample configurations, Pt redistributes in an erratic way. This phenomenon can be assigned to the low solubility of Pt in Ni2Si compared to NiSi and the high mobility of Pt in Ni2Si compared to pure Ni. Real-time RBS further revealed that the crucial issue determining the growth properties of each silicide phase is the Pt concentration at the Si interface during the initial stages of phase formation. The formation of areas rich in Pt reduce the Ni silicide growth kinetics which influences the phase sequence and properties of the silicides.
Compositional dependent thin film stress states
Authors: Fu B. , Thompson G. B.
Published: August 2010

This paper addresses in situ stress evolution of two-component FexPt1−x, where x spanned 0 to 1, alloy thin films. The stresses of the high-temperature, quenched-in, solid solution phase was determined by in situ wafer curvature measurements during ambient temperature growth. The measured stresses were shown to be compositional dependent and spanned both compressive and tensile stress states. Under specific growth conditions, a “zero-stress” state could be achieved. The alloy stress states did not show any significant stress recovery upon ceasing the deposition, i.e. the stress state during growth was retained in the film. X-ray diffraction, transmission electron microscopy, and atom probe tomography were used to characterize the microstructures of each thin film. The evolution of the stress state with composition is described in terms of a chemical potential term for preferential segregation of one species in the alloy to the grain boundaries.
Transport dynamics with alternate Cooper-pair and quasiparticle tunnelings in one-dimensional charge Josephson arrays
Authors: Ho I. L. , Lin M. C. , Aravind K. , Wu C. S. , Chen C. D.
Published: August 2010

For a single weak-coupled Josephson junction, stochastic Cooper-pair tunnelings drive the superconducting current on low voltage biases, while quasiparticle tunnelings stimulate the normal current on high biases above the superconducting gap voltage. Considering these interactive dynamics simultaneously in one-dimensional weak-coupled Josephson arrays in electrodynamic environments, the theoretical work by rate equations is structured herein, and the charge transport associated with short-range (Cooper pair and quasiparticle) and long-range (Cooper-pair soliton and quasiparticle soliton) behaviors is analyzed.
Fiber optic based system for polarization sensitive spectroscopy of semiconductor quantum structures
Authors: Arora Ashish , Karmakar Biswajit , Sharma Sayantan , Schardt Michael , Malzer Stefan , Bansal Bhavtosh , Döhler Gottfried , Arora Brij M.
Published: August 2010

We describe an optical fiber based setup for performing polarization resolved magneto-optical spectroscopy measurements under low temperatures (∼4 K) and high magnetic fields (∼8 T). The measurements are performed in a windowless helium Dewar. Circularly polarized light is produced inside the Dewar by inserting the polarizing elements between the fiber end and the sample. Photoconductivity spectra of a GaAs/AlGaAs multiquantum-well sample have been measured over the photon energy range of 1.5–1.7 eV in left and right circularly polarized light under crossed magnetic and electric fields. It is shown that reversing the direction of magnetic field produces the same spectral changes as caused by changing the direction of circular polarization with the optical components.
A simple bilayered magnetoelectric random access memory cell based on electric-field controllable domain structure
Authors: Hu Jia-Mian , Li Zheng , Wang Jing , Ma Jing , Lin Y. H. , Nan C. W.
Published: August 2010

By considering the domain wall scattering in ferromagnetic striped-domain structure, we present a simple bilayered magnetoelectric random access memory cell with a ferromagnetic thin film grown on a ferroelectric layer. The calculations show that the striped-domain structure in the ferromagnetic film can change into a single-domain structure upon applying an electric field to the ferroelectric layer. As a result, the presence (absence) of the domain walls in response to the striped-domain (single-domain) state can cause an abrupt change in the film resistivity, which could be employed for memory applications accordingly.
Design and characterization of a field-switchable nanomagnetic atom mirror
Authors: Hayward T. J. , West A. D. , Weatherill K. J. , Curran P. J. , Fry P. W. , Fundi P. M. , Gibbs M. R. J. , Schrefl T. , Adams C. S. , Hughes I. G. , Bending S. J. , Allwood D. A.
Published: August 2010

We present a design for a switchable nanomagnetic atom mirror formed by an array of 180° domain walls confined within Ni80Fe20 planar nanowires. A simple analytical model is developed which allows the magnetic field produced by the domain wall array to be calculated. This model is then used to optimize the geometry of the nanowires so as to maximize the reflectivity of the atom mirror. We then describe the fabrication of a nanowire array and characterize its magnetic behavior using magneto-optic Kerr effect magnetometry, scanning Hall probe microscopy, and micromagnetic simulations, demonstrating how the mobility of the domain walls allow the atom mirror to be switched “on” and “off” in a manner which would be impossible for conventional designs. Finally, we model the reflection of R87b atoms from the atom mirror’s surface, showing that our design is well suited for investigating interactions between domain walls and cold atoms.
Stochastic deformation of integrable dynamical systems and random time symmetry
Authors: Privault Nicolas , Zambrini Jean-Claude
Published: August 2010

We present a deformation of a class of elementary classical integrable systems using stochastic diffusion processes. This deformation applies to the solution of the associated classical Newtonian, Hamiltonian, Lagrangian, and variational problems and to the Hamilton–Jacobi method of characteristics. The underlying stochastic action functionals involve dual random times, whose expectations are connected to the new variables of the system after a canonical transformation.
Surface preparation and homoepitaxial deposition of AlN on (0001)-oriented AlN substrates by metalorganic chemical vapor deposition
Authors: Rice A. , Collazo R. , Tweedie J. , Dalmau R. , Mita S. , Xie J. , Sitar Z.
Published: August 2010

Chemical surface treatments were conducted on mechanically polished (MP) and chemomechanically polished (CMP) (0001)-oriented single crystalline aluminum nitride (AlN) substrates to determine a surface preparation procedure for the homoepitaxial deposition of AlN epitaxial layers by metalorganic chemical vapor deposition. MP AlN substrates characterized by atomic force microscopy exhibited 0.5 nm rms roughness and polishing scratches, while CMP AlN substrates exhibited 0.1 nm rms roughness and were scratch-free. X-ray photoelectron spectroscopy analysis of MP and CMP AlN substrates indicated the presence of a surface hydroxide layer composed of mixed aluminum oxide hydroxide and aluminum trihydroxide. Wet etching with sulfuric and phosphoric acid mixtures reduced the amount of surface hydroxide. Ammonia annealing at 1250 °C converted the substrate hydroxide layer to AlN and increased the rms roughness of MP and CMP AlN substrates to 2.2 nm and 0.2 nm, respectively. AlN epitaxial layers were deposited at 1100–1250 °C under 20 Torr total pressure with a V/III ratio of 180–300 in either N2 or H2 diluent. High-resolution x-ray diffraction measurements revealed that AlN epitaxial layers deposited on MP substrates were strained due to nucleation and coalescence of AlN grains on the mechanically damaged surfaces. AlN deposited on CMP substrates was epitaxial and strain-free. Thermodynamic models for nitridation and AlN deposition were also proposed and evaluated.
Area fraction quantification of ferroelectric domain orientations in BaTiO3 using piezoresponse force microscopy
Authors: Fernandes Rodrigo P. , Herber Ralf-Peter , Kunz Lothar , Mgbemere Henry E. , Schneider Gerold A.
Published: August 2010

Understanding the domain structure of ferroelectric ceramics is very important to develop sound knowledge of the influence of the microstructure on the macroscopic properties. To proceed in this direction, experimental tools are necessary in order to quantify the domain patterns in ferroelectrics. This study on BaTiO3 single crystals exemplifies how vector piezoresponse force microscopy can be used to obtain statistical information about domain directions.
Fabrication and photoluminescence of ZnS:Mn2+ nanowires/ZnO quantum dots/SiO2 heterostructure
Authors: Yang Jinghai , Cao Jian , Yang Lili , Zhang Yongjun , Wang Yaxin , Liu Xiaoyan , Wang Dandan , Wei Maobin , Gao Ming , Lang Jihui
Published: August 2010

In this paper, we demonstrated the encapsulation of ZnS:Mn2+ nanowires (NWs) and ZnO quantum dots (QDs) with a layer of mesoporous SiO2 shell for the purpose of integrating dual emission property into one common nanostructure. The average diameter of ZnS:Mn2+ NWs, ZnO QDs, and ZnS:Mn2+/ZnO@SiO2 heterostructure was about 10 nm, 6 nm, and 22 nm, respectively. Within ZnS:Mn2+/ZnO@SiO2 nanocomposites, the intensity of the yellow-orange emission contributed by ZnS:Mn2+ NWs and the UV emission contributed by ZnO QDs was three and ten times higher than their individual components, respectively. The fluorescence intensity ratio of the dual emission can be tuned by adjusting the hydrolysis time of tetraethyl orthosilicate. The peak energy of the yellow-orange and UV emission showed blueshift and redshift as increasing the temperature, respectively. The anomalous enhancement of the integrated intensity for the UV emission with the temperature indicated that the high surface state density existing in ZnO QDs can overrun the influence of temperature quenching and even alter the photoluminescent properties.
Anisotropic magnetostriction in a ⟨110⟩ oriented crystal Tb0.36Dy0.64(Fe0.85Co0.15)2 after coaxial field annealing
Authors: Zhang Changsheng , Ma Tianyu , Qi Ruilei , Yan Mi
Published: August 2010

Axial magnetostriction of Terfenol-D oriented crystals is highly anisotropic when changing the magnetization direction. Magnetostrictions of a ⟨110⟩ oriented crystal Tb0.36Dy0.64(Fe0.85Co0.15)2 were investigated under magnetic fields with a series of angles θ to its axis. Totally different anisotropic magnetostrictive behaviors are observed after annealing under a coaxial field of 240 kA/m. The magnetostriction for the field annealed specimen seems unsaturated even under 640 kA/m for angles θ in the range from 0° to 55°. At these angles, magnetostriction “ascending” is observed during the final magnetization process, while magnetostriction “dropping” occurs at angles above 35° for the untreated crystal. With the increase in angle θ, the corresponding field where magnetostriction starts dropping decreases for the untreated crystal, while the field at which magnetostriction starts ascending increases for the field annealed one. A simplified model based on moment “jump” and “rotation” is proposed to explain such anisotropic behaviors.
Potential energy surface studies via a single root multireference coupled cluster theory
Authors: Mahapatra Uttam Sinha , Chattopadhyay Sudip
Published: August 2010

We have employed complete active space based single root multireference coupled cluster method (the resulting method is referred to by the acronym sr-MRCC) to compute the potential energy surfaces (PESs) of some well studied “protypical model” systems for which a highly accurate and reliable database is available for comparison. As that of state-specific theory, the sr-MRCC approach focuses and correlates one state while using a multiconfigurational reference and thus it naturally avoids intruder states. The present method is structurally different from the well known state specific multireference coupled cluster (SS-MRCC) method introduced by Mahapatra et al. [Mol. Phys. 94, 157 (1998)]. As that of the SS-MRCC theory, the present method is also based on the Jeziorski–Monkhorst ansatz where a different exponential cluster operator exp(Tμ) acts on its corresponding model function ϕμ. The final cluster finding equations contain coupling between the cluster operators for all the μ, which are mainly responsible to prove the extensivity of both the cluster amplitudes and the energy. The present sr-MRCC theory is size-extensive and size-consistent when localized orbitals are used. The systems considered here exhibit varying degrees of degeneracy at different regions of PES. The treatment of these systems via traditional effective Hamiltonian based methods suffers from divergence problems in the iterative solution of the CC equations (the issue termed as “intruder state”). The sr-MRCC results lie closer to the ones obtained by the SS-MRCC method for these systems. To judge the efficacy of the present method, we have compared our results with other previously published theoretical estimations, which clearly indicate that the present method is reliable in studying the dissociation PES of states plagued by electronic degeneracy as well as notorious intruder effects. The highly satisfactory performance of the sr-MRCC method, vis-à-vis the other sophisticated methods, in describing the lowest and the first excited singlet states of BeH2 at points of high degeneracy is noticeable.
Hydrogen-bonding alcohol-water interactions in binary ethanol, 1-propanol, and 2-propanol+methane structure II clathrate hydrates
Authors: Alavi Saman , Takeya Satoshi , Ohmura Ryo , Woo Tom K. , Ripmeester John A.
Published: August 2010

The small alcohols ethanol, 1-propanol, and 2-propanol are miscible in water, form strong hydrogen bonds with water molecules, and are usually known as inhibitors for clathrate hydrate formation. However, in the presence of methane or other help gases, clathrate hydrates of these substances have been synthesized. In this work, molecular dynamics simulations are used to characterize guest-host hydrogen bonding, microscopic structures, and guest dynamics of binary structure II clathrate hydrates of methane (small cages) with ethanol, 1-propanol, and 2-propanol in the temperature range of 100–250 K to gain insight into the stability of these materials. We observe that these alcohols form structures with dynamic long-lived (∼10 ps) guest-host hydrogen bonds in the hydrate phases while maintaining the general cage structure of the sII clathrate hydrate form. The hydroxyl groups of ethanol, 1-propanol, and 2-propanol act as both proton acceptors and proton donors and there is a considerable probability of simultaneous hydrogen bonding between O and H hydroxyl atoms with different cage water molecules. The presence of the nonpolar methane molecule and the hydrophobic moieties of the alcohols stabilize the hydrate phase, despite the strong and prevalent alcohol-water hydrogen bonding. The effect of the alcohol molecules on the structural properties of the hydrate and the effect of guest-host hydrogen bonding on the guest dynamics are studied.
Subexponential instability in one-dimensional maps implies infinite invariant measure
Authors: Akimoto Takuma , Aizawa Yoji
Published: August 2010

We characterize dynamical instability of weak chaos as subexponential instability. We show that a one-dimensional, conservative, ergodic measure preserving map with subexponential instability has an infinite invariant measure, and then we present a generalized Lyapunov exponent to characterize subexponential instability.
On the continuity of spectra for families of magnetic pseudodifferential operators
Authors: Athmouni Nassim , Măntoiu Marius , Purice Radu
Published: August 2010

For families of magnetic pseudodifferential operators defined by symbols and magnetic fields depending continuously on a real parameter ϵ, we show that the corresponding family of spectra also varies continuously with ϵ.
On the calculation of charge transfer transitions with standard density functionals using constrained variational density functional theory
Authors: Ziegler Tom , Krykunov Mykhaylo
Published: August 2010

It is well known that time-dependent density functional theory (TD-DFT) based on standard gradient corrected functionals affords both a quantitative and qualitative incorrect picture of charge transfer transitions between two spatially separated regions. It is shown here that the well known failure can be traced back to the use of linear response theory. Further, it is demonstrated that the inclusion of higher order terms readily affords a qualitatively correct picture even for simple functionals based on the local density approximation. The inclusion of these terms is done within the framework of a newly developed variational approach to excitation energies called constrained variational density functional theory (CV-DFT). To second order [CV(2)-DFT] this theory is identical to adiabatic TD-DFT within the Tamm–Dancoff approximation. With inclusion of fourth order corrections [CV(4)-DFT] it affords a qualitative correct description of charge transfer transitions. It is finally demonstrated that the relaxation of the ground state Kohn–Sham orbitals to first order in response to the change in density on excitation together with CV(4)-DFT affords charge transfer excitations in good agreement with experiment. The new relaxed theory is termed R-CV(4)-DFT. The relaxed scheme represents an effective way in which to introduce double replacements into the description of single electron excitations, something that would otherwise require a frequency dependent kernel.
A charge pumping technique to identify biomolecular charge polarity using a nanogap embedded biotransistor
Authors: Kim Sungho , Kim Jee-Yeon , Ahn Jae-Hyuk , Park Tae Jung , Lee Sang Yup , Choi Yang-Kyu
Published: August 2010

Charge pumping technique is investigated to identify biomolecular charge polarity using a nanogap-embedded biotransistor. Biomolecules immobilized in a nanogap provide additional charges in the gate dielectric. They give rise to a change in the charge pumping current, as detected by applying a designed pulse waveform. The measured results are analyzed with the aid of numerical simulations. The proposed charge pumping technique represents an insightful method of investigating the electrical properties of biomolecules beyond biosensing.
The role of kinetic effects, including plasma rotation and energetic particles, in resistive wall mode stability
Authors: Berkery J. W. , Sabbagh S. A. , Reimerdes H. , Betti R. , Hu B. , Bell R. E. , Gerhardt S. P. , Manickam J. , Podestà M.
Published: August 2010

The resistive wall mode (RWM) instability in high-beta tokamaks is stabilized by energy dissipation mechanisms that depend on plasma rotation and kinetic effects. Kinetic modification of ideal stability calculated with the “MISK” code [B. Hu et al., Phys. Plasmas 12, 057301 (2005)] is outlined. For an advanced scenario ITER [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)] plasma, the present calculation finds that alpha particles are required for RWM stability at presently expected levels of plasma rotation. Kinetic stabilization theory is tested in an experiment in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] that produced marginally stable plasmas with various energetic particle contents. Plasmas with the highest and lowest energetic particle content agree with calculations predicting that increased energetic particle pressure is stabilizing but does not alter the nonmonotonic dependence of stability on plasma rotation due to thermal particle resonances. Presently, the full MISK model, including thermal particles and an isotropic slowing-down distribution function for energetic particles, overpredicts stability in NSTX experiments. Minor alteration of either effect in the theory may yield agreement; several possibilities are discussed.
Poling effect and piezoelectric response in high-strain ferroelectric 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 crystal
Authors: Chen H.-Y. , Tu C.-S. , Hung C.-M. , Chien R. R. , Schmidt V. H. , Ku C.-S. , Lee H.-Y.
Published: August 2010

In situ high-resolution synchrotron x-ray diffraction, dielectric permittivity, hysteresis loop, and polarization current, were used to investigate phase transitions of (211)-cut 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 single crystal before and after an electric (E) field poling. A rhombohedral (R)–tetragonal (T)–cubic transition sequence was observed upon zero-field heating in both unpoled and poled samples. Before the R–T transition takes place, an extra dielectric and polarization current anomalies near 365 K were observed in the poled sample due to a transition of polarization ordering. The direct piezoelectric coefficient d33 exhibits a rapid increase for poling at E=1.0–1.3 kV/cm, followed by an overpoling behavior. The increment of polarization ordering plays an important role while the high piezoelectric response builds up.
ZnO-organic hybrid white light emitting diodes grown on flexible plastic using low temperature aqueous chemical method
Authors: Bano N. , Zaman S. , Zainelabdin A. , Hussain S. , Hussain I. , Nur O. , Willander M.
Published: August 2010

We demonstrate white light luminescence from ZnO-organic hybrid light emitting diodes grown at 90 °C on flexible plastic substrate by aqueous chemical growth. The configuration used for the ZnO-organic hybrid white light emitting diodes (WLEDs) consists of a layer of poly (9, 9-dioctylfluorene) (PFO) on poly (3, 4-ethylenedioxythiophene) poly (styrenesulfonate) coated plastic with top ZnO nanorods. Structural, electrical, and optical properties of these WLEDs were measured and analyzed. Room temperature electroluminescence spectrum reveals a broad emission band covering the range from 420 to 750 nm. In order to distinguish the white light components and contribution of the PFO layer we used a Gaussian function to simulate the experimental data. Color coordinates measurement of the WLED reveals that the emitted light has a white impression. The color rendering index and correlated color temperature of the WLED were calculated to be 68 and 5800 K, respectively.
Domain structures and piezoelectric properties of Pb(Zr0.2Ti0.8)O3 nanocapacitors
Authors: Han Hee , Park Yong Jun , Baik Sunggi , Lee Woo , Alexe Marin , Hesse Dietrich , Gösele Ulrich
Published: August 2010

Epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) nanoislands and nanocapacitors were fabricated by stencil mask-assisted pulsed laser deposition. By x-ray diffraction reciprocal space mapping it was observed that PZT nanoislands contain mainly c-domains and residual fractions of tilted and nontilted a-domains, while extended thin films contain only c-domains and tilted a-domains. The presence of nontilted a-domains manifests clearly that the misfit strain is significantly reduced in PZT nanoislands, compared to the thin film. Some of the a-domains turned out to be switchable under an external electric field due to the strain relaxation in the PZT nanocapacitors. The piezoresponse of PZT nanocapacitors was higher than that of continuous thin-film capacitors.
Impact of a compound droplet on a flat surface: A model for single cell epitaxy
Authors: Tasoglu Savas , Kaynak Gozde , Szeri Andrew J. , Demirci Utkan , Muradoglu Metin
Published: August 2010

The impact and spreading of a compound viscous droplet on a flat surface are studied computationally using a front-tracking method as a model for the single cell epitaxy. This is a technology developed to create two-dimensional and three-dimensional tissue constructs cell by cell by printing cell-encapsulating droplets precisely on a substrate using an existing ink-jet printing method. The success of cell printing mainly depends on the cell viability during the printing process, which requires a deeper understanding of the impact dynamics of encapsulated cells onto a solid surface. The present study is a first step in developing a model for deposition of cell-encapsulating droplets. The inner droplet representing the cell, the encapsulating droplet, and the ambient fluid are all assumed to be Newtonian. Simulations are performed for a range of dimensionless parameters to probe the deformation and rate of deformation of the encapsulated cell, which are both hypothesized to be related to cell damage. The deformation of the inner droplet consistently increases: as the Reynolds number increases; as the diameter ratio of the encapsulating droplet to the cell decreases; as the ratio of surface tensions of the air-solution interface to the solution-cell interface increases; as the viscosity ratio of the cell to encapsulating droplet decreases; or as the equilibrium contact angle decreases. It is observed that maximum deformation for a range of Weber numbers has (at least) one local minimum at We=2. Thereafter, the effects of cell deformation on viability are estimated by employing a correlation based on the experimental data of compression of cells between parallel plates. These results provide insight into achieving optimal parameter ranges for maximal cell viability during cell printing.
Influence of the excitonic broadening on the strong light-matter coupling in bulk zinc oxide microcavities
Authors: Médard F. , Lagarde D. , Zúñiga-Pérez J. , Disseix P. , Mihailovic M. , Leymarie J. , Frayssinet E. , Moreno J. C. , Semond F. , Leroux M. , Bouchoule S.
Published: August 2010

We present an experimental study of the influence of excitonic broadening on the strong-coupling regime in a bulk-ZnO microcavity. At room temperature, the strong coupling is highlighted using both angle-resolved reflectivity and photoluminescence measurements; a Rabi splitting value of 40 meV is determined. The polaritonic behavior is also evidenced at low temperature, even if a bulklike reflectivity signature is observed in the excitonic range. Using transfer-matrix calculations, this phenomenon is explained through the influence of the huge excitonic absorption whose contribution depends on the broadening value. Finally, we demonstrate that this effect should not prevent a lasing from the polaritons.
Oxygen pressure dependence of structure and electrical properties of pulsed laser deposited Ba(Fe1/2Nb1/2)O3 thin films
Authors: Zhang Wei , Li Lei , Chen Xiang Ming
Published: August 2010

The role of oxygen pressure on the microstructure, dielectric properties, and leakage mechanisms of polycrystalline Ba(Fe1/2Nb1/2)O3 thin films grown by pulsed laser deposition was investigated. Strong oxygen pressure dependence of the crystal structure was observed together with the structure distortion. Investigation on the dielectric properties showed the multidispersive relaxation nature for all Ba(Fe1/2Nb1/2)O3 thin films. The conduction properties of Ba(Fe1/2Nb1/2)O3 thin films prepared in various oxygen pressures were also discussed. Space-charge-limited conduction may have a dominant role in the thin films deposited in 1 and 15 Pa oxygen pressure, and for the thin films grown in 10 Pa, the Poole–Frenkel conduction was suggested. While for the thin films deposited in 5 Pa, there was no clear dominant mechanism.
Homologous series of iron pnictide oxide superconductors (Fe2As2)[Can+1(Sc,Ti)nOy] (n=3,4,5) with extremely thick blocking layers
Authors: Ogino Hiraku , Sato Shinya , Kishio Kohji , Shimoyama Jun-ichi , Tohei Tetsuya , Ikuhara Yuichi
Published: August 2010

We have discovered homologous series of iron pnictide superconductors (Fe2As2)[Can+1(Sc,Ti)nOy] (n=3,4,5). These compounds have extremely thick blocking layers up to quintuple perovskite layers sandwiched by the Fe2As2 layers. These samples exhibited bulk superconductivity with relatively high Tc up to 42 K. The relationship between Tc and the iron-plane interlayer distance suggested that Tc of the iron based superconductor is basically determined by the local structure of Fe2As2 layer.
High-Reynolds-number turbulent-boundary-layer wall-pressure fluctuations with dilute polymer solutions
Authors: Elbing Brian R. , Winkel Eric S. , Ceccio Steven L. , Perlin Marc , Dowling David R.
Published: August 2010

Wall-pressure fluctuations were investigated within a high-Reynolds-number turbulent boundary layer (TBL) modified by the addition of dilute friction-drag-reducing polymer solutions. The experiment was conducted at the U.S. Navy’s Large Cavitation Channel on a 12.9 m long flat-plate test model with the surface hydraulically smooth (k+<0.2) and achieving downstream-distance-based Reynolds numbers to 220×106. The polymer (polyethylene oxide) solution was injected into the TBL through a slot in the surface. The primary flow diagnostics were skin-friction drag balances and an array of flush-mounted dynamic pressure transducers 9.8 m from the model leading edge. Parameters varied included the free-stream speed (6.7, 13.4, and 20.2 m s−1) and the injection condition (polymer molecular weight, injection concentration, and volumetric injection flux). The behavior of the pressure spectra, convection velocity, and coherence, regardless of the injection condition, were determined primarily based on the level of drag reduction. Results were divided into two regimes dependent on the level of polymer drag reduction (PDR), nominally separated at a PDR of 40%. The low-PDR regime is characterized by decreasing mean-square pressure fluctuations and increasing convection velocity with increasing drag reduction. This shows that the decrease in the pressure spectra with increasing drag reduction is due in part to the moving of the turbulent structures from the wall. Conversely, with further increases in drag reduction, the high-PDR regime has negligible variation in the mean-squared pressure fluctuations and convection velocity. The convection velocity remains constant at approximately 10% above the baseline-flow convection velocity, which suggests that the turbulent structures no longer move farther from the wall with increasing drag reduction. In light of recent numerical work, the coherence results indicate that in the low-PDR regime, the turbulent structures are being elongated in the streamwise direction and occurring at decreasing frequency. In the high-PDR regime, the rate of occurrence continues to decrease until large-scale coherent turbulent structures are potentially no longer present.
Dissimilarity of polar displacements in barium and lead based relaxors
Authors: Phelan D. , Millican J. N. , Gehring P. M.
Published: August 2010

Powder neutron diffraction experiments were performed on the relaxor compound, Ba(Zn1/3Nb2/3)0.95Ti0.05O3, which was recently shown to have stronger frequency dependence in its permittivity than many Pb-based relaxors (PBR), such as PbMg1/3Nb2/3O3 [L. Khemakhem et al., J. Alloys Compd. 452, 451 (2008)]. Several notable differences in structural properties were observed in the present measurements compared to PBR. In particular, much smaller atomic displacement parameters were found, especially on the A (Ba) site, which indicates that the local shifts of the Ba atoms are much smaller than the Pb shifts in PBR. Moreover, no signature of electrostrictive strain is apparent in the thermal expansion, and instead the thermal expansion is much larger at low temperatures than for PBR.
Transition probabilities and measurement statistics of postselected ensembles
Authors: Fritz Tobias
Published: August 2010

It is well-known that a quantum measurement can enhance the transition probability between two quantum states. Such a measurement operates after preparation of the initial state and before postselecting for the final state. Here we analyze this kind of scenario in detail and determine which probability distributions on a finite number of outcomes can occur for an intermediate measurement with postselection, for given values of the following two quantities: (i) the transition probability without measurement and (ii) the transition probability with measurement. This is done for both the cases of projective measurements and of generalized measurements. Among other constraints, this quantifies a trade-off between high randomness in a projective measurement and high measurement-modified transition probability. An intermediate projective measurement can enhance a transition probability such that the failure probability decreases by a factor of up to 2, but not by more.
Polarity-controlled visible/infrared electroluminescence in Si-nanocrystal/Si light-emitting devices
Authors: Liu Zhihong , Huang Jiandong , Joshi Pooran C. , Voutsas Apostolos T. , Hartzell John , Capasso Federico , Bao Jiming
Published: August 2010

We report the demonstration of a room-temperature visible/infrared color-switchable light-emitting device comprising a Si nanocrystal-embedded silicon oxide thin film on a p-type Si substrate. The device emits band-edge infrared light from the silicon substrate when the substrate is positively (forward) biased with respect to the Si-nanocrystal film. Under reverse bias, visible emission from the Si-nanocrystal film is observed. Compared to the photoluminescence of the Si-nanocrystal film, the visible electroluminescence is broader and blueshifted to shorter wavelength, and is ascribed to impact ionization in the Si-nanocrystal/SiO2 film.
Low-threshold terahertz quantum-cascade lasers based on GaAs/Al0.25Ga0.75As heterostructures
Authors: Wienold M. , Schrottke L. , Giehler M. , Hey R. , Anders W. , Grahn H. T.
Published: August 2010

We investigated the influence of the barrier composition on the performance of GaAs-based terahertz (THz) quantum-cascade lasers (QCLs). Based on a nine-quantum-well active region design for 3–4 THz emission, QCLs with an Al content of x=0.15 and x=0.25 in the AlxGa1−xAs barriers are compared. We found a significantly reduced threshold current density for QCLs with x=0.25 as compared to QCLs with x=0.15, which is due to a weaker coupling of the subband states. The maximum output power and operating temperature of such lasers are reduced due to the onset of negative differential resistance.
Surface plasmon-enhanced light emission using silver nanoparticles embedded in ZnO
Authors: Xiao X. H. , Ren F. , Zhou X. D. , Peng T. C. , Wu W. , Peng X. N. , Yu X. F. , Jiang C. Z.
Published: August 2010

The Ag nanoparticles-SiO2–ZnO film sandwiched structure was fabricated by depositing ZnO films on silica substrates which had been implanted by Ag ions. Enhancement of emission of the sandwiched structure was observed. The enhancement emission is caused by the resonant coupling between the surface plasmons of Ag and the spontaneous emission of ZnO. The enhancement mechanism is confirmed by optical absorption spectra, transmission electron microscopy, and time-resolved photoluminescence. The key is to deposit ZnO on Ag nanoparticles covered with silica to prevent oxidation of Ag by direct contact with ZnO. This structure will be very useful for highly efficient optoelectronic devices.
Low-frequency noise in strained SiGe core-shell nanowire p-channel field effect transistors
Authors: Jang Doyoung , Lee Jae Woo , Tachi Kiichi , Montes Laurent , Ernst Thomas , Kim Gyu Tae , Ghibaudo Gerard
Published: August 2010

Low-frequency noise has been studied in compressively strained Si0.8Ge0.2 core-shell nanowire (NW) p-channel transistors compared with unstrained NWs. The noise has been well interpreted using the carrier number with correlated mobility fluctuation model. The volume trap density, Nt, lies in the range of 2.9×1018–4.3×1019 cm−3 eV−1, which is similar to standard high-k planar devices. The impact of Coulomb and surface roughness scatterings is more significant in unstrained SiGe NWs. This result can be explained by the better carrier confinement at the central region of SiGe NWs due to the additional band offset in the compressively strained NWs.
Experimental exploration of the origin of magnetostriction in single crystalline iron
Authors: Xing Q. , Lograsso T. A. , Ruffoni M. P. , Azimonte C. , Pascarelli S. , Miller D. J.
Published: August 2010

The magnetostrictive atomic strain in a pure Fe single crystal was measured by differential x-ray absorption spectroscopy. The obtained tetragonal magnetostriction constant, (3/2)λ100, was determined to be 45 ppm, consistent with the previously reported theoretical value calculated from a spin-orbit coupling theory. These results provide a foundation for understanding the origin of magnetostriction in pure Fe as well as Fe-based binary alloys.
Millimeter wave phase shifter based on ferromagnetic resonance in a hexagonal barium ferrite thin film
Authors: Wang Zihui , Song Young-Yeal , Sun Yiyan , Bevivino Joshua , Wu Mingzhong , Veerakumar V. , Fal Timothy J. , Camley Robert E.
Published: August 2010

A hexagonal ferrite thin film-based planar millimeter-wave phase shifter was demonstrated. The device made use of an M-type barium ferrite (BaM) thin film prepared by pulsed laser deposition and a coplanar waveguide geometry. The phase tuning relied on ferromagnetic resonance in the BaM film. The device showed a phase tuning rate of 43°/(mm kOe) and an insertion loss of 3.1 dB/mm in the on-resonance regime. In off-resonance regimes, the device showed smaller loss and smaller tuning rates. The experimental results were confirmed by theoretical calculations.
Low-noise submicron channel graphene nanoribbons
Authors: Xu Guangyu , Bai Jingwei , Torres Carlos M. , Song Emil B. , Tang Jianshi , Zhou Yi , Duan Xiangfeng , Zhang Yuegang , Wang Kang L.
Published: August 2010

We present a graphene nanoribbon fabrication method based on a nanowire mask. Using a four-probe setup, single-layer nanoribbon (SLR) and bilayer nanoribbon (BLR) show low-frequency noise levels lower than (comparable to) the SLRs (BLRs) achieved by hydrogen-silsesquioxane based methods. Submicron channel SLR and BLR both show conductance quantization at 77 K, which suggests that quasi-one-dimensional quantum transport can be achieved. The conductance plateaus in BLR are less pronounced than those in SLR.
Microcrystalline silicon thin-film transistors operating at very high frequencies
Authors: Marinkovic Marko , Hashem Elias , Chan Kah-Yoong , Gordijn Aad , Stiebig Helmut , Knipp Dietmar
Published: August 2010

The switching behavior of hydrogenated microcrystalline silicon thin-film transistors (TFTs) was examined and switching frequencies exceeding 20 MHz were measured for short channel devices. The microcrystalline silicon TFTs were prepared by plasma-enhanced chemical vapor deposition at temperatures compatible with plastic substrates. The realized microcrystalline silicon transistors exhibit high electron charge carrier mobilities of 130 cm2/V s. The switching frequency is limited by the contact resistances and overlap capacitances between the gate and the drain/source electrodes. Switching frequencies larger than 20 MHz were measured for transistors with a channel length of 5 μm. The high switching frequencies facilitate the realization of radio-frequency identification tags operating at 13.56 MHz.
Availability of Advance Visual Information Constrains Association-Football Goalkeeping Performance during Penalty Kicks
Authors: Dicks Matt , Button Chris , Davids Keith
Published: August 2010

A pressing concern within the literature on anticipatory perceptual-motor behaviour is the lack of clarity on the applicability of data, observed under video-simulation task constraints, to actual performance in which actions are coupled to perception, as captured during in-situ experimental conditions. We developed an in-situ experimental paradigm which manipulated the duration of anticipatory visual information from a penalty taker's actions to examine experienced goalkeepers' vulnerability to deception for the penalty kick in association football. Irrespective of the penalty taker's kick strategy, goalkeepers initiated movement responses earlier across consecutively earlier presentation points. Overall goalkeeping performance was better in non-deception trials than in deception conditions. In deception trials, the kinematic information presented up until the penalty taker initiated his/her kicking action had a negative effect on goalkeepers' performance. It is concluded that goalkeepers are likely to benefit from not anticipating a penalty taker's performance outcome based on information from the run-up, in preference to later information that emerges just before the initiation of the penalty taker's kicking action.
Processes Underlying the Cross-Race Effect: An Investigation of Holistic, Featural, and Relational Processing of Own-Race versus Other-Race Faces
Authors: Mondloch Catherine J , Elms Natalie , Maurer Daphne , Rhodes Gillian , Hayward William G , Tanaka James W , Zhou Guomei
Published: August 2010

Adults are often better at recognising own-race than other-race faces. Unlike previous studies that reported an own-race advantage after administering a single test of either holistic processing or of featural and relational processing, we used a cross-over design and multiple tasks to assess differential processing of faces from a familiar race versus a less familiar race. Caucasian and Chinese adults performed four tasks, each with Caucasian and Chinese faces. Two tasks measured holistic processing: the composite face task and the part/whole task. Both tasks indicated holistic processing of own-race and other-race faces that did not differ in degree. Two tasks measured featural and relational processing: the Jane/Ling task, in which same/different judgments were made about face pairs that differed in features of their spacing, and the scrambled/blurred task, in which test faces were scrambled (isolates memory for components) or blurred (isolates memory for relations). Both tasks provided evidence of an own-race advantage in both featural and relational processing. We conclude that even when adults process other-race faces holistically, other manifestations of an own-race advantage remain.
Does Thompson's Thatcher Effect Reflect a Face-Specific Mechanism?
Authors: Wong Yetta K , Twedt Elyssa , Sheinberg David , Gauthier Isabel
Published: August 2010

The Thatcher Illusion or Thatcher Effect (TE—Thompson 1980, Perception 9 483–484) reflects the difficulty in perceiving the local inversion of parts when the whole object, generally a face, is globally inverted. We tested the generality of the TE with a range of faces and non-face objects, and observed the TE with many non-face categories including cars, buildings, bikes, and letter strings. In terms of magnitude, the face TE is not exceptionally large compared to other object categories, and the magnitude of the TE can be predicted by performance on this task for upright stimuli, regardless of whether the object is a face or not. We did not observe evidence for a unique mechanism contributing to the TE for faces. We discuss factors that influence the magnitude of the TE, some common across domains and others more specific to a particular category.