bluuebunny/crossref_metadata_2025 huggingface dataset:
Das Instrument zur Kodierung von Diskussionen (IKD)
Authors: Schermuly Carsten C. , Schröder Tobias , Nachtwei Jens , Scholl Wolfgang
Published: October 2010

Das Instrument zur Kodierung von Diskussionen (IKD) ist ein neues und nutzerfreundliches Verfahren, mit dem Interaktionsprozesse in Organisationen zeitökonomisch kodiert werden können. Somit wird es möglich, eine größere Anzahl von Gruppen und Kommunikationssituationen (z. B. Entscheidungssitzungen, Teambesprechungen oder Mitarbeitergespräche) Akt für Akt standardisiert zu beobachten und zu analysieren. Mit dem IKD werden zwei Arten von Kommunikationsebenen gleichzeitig untersucht: die interpersonale und die funktionale Bedeutung einer Aussage. In der vorliegenden Studie wurden zur Prüfung der Zuverlässigkeit und Validität 60 Dyaden bei einer interaktiven Aufgabe mit verteilten Rollen (Vorgesetzter, Mitarbeiter) im Rahmen eines Assessment-Centers mit dem IKD beobachtet. Es konnten hohe Beobachterübereinstimmungsergebnisse ermittelt werden (Kappawerte und unjustierte Intraklassenkorrelationen ≥ .80). Bei der Validitätsprüfung wurden Zusammenhänge der IKD-Variablen mit Persönlichkeits- und Intelligenzmerkmalen festgestellt. Ebenso konnten ein Priming sowie die Vorgesetzten- und Mitarbeiterrolle weitestgehend hypothesenkonform in den IKD-Daten nachgewiesen werden.
Selbstregulationsstärke und Leistung
Authors: Stumm Sebastian , Thomas Edgar , Dormann Christian
Published: October 2010

In der modernen Arbeitswelt ist der anhaltende Trend zu einer stärkeren Eigenverantwortung der Beschäftigten zu beobachten. Hierdurch zunehmende Handlungsspielräume erfordern ein hohes Maß an Selbstregulation. Selbstregulationsprozesse finden vornehmlich in volitional gesteuerten Handlungsphasen statt, um das eigene Verhalten, Emotionen und Kognitionen beispielsweise den Organisationszielen entsprechend auszurichten. Geht man von einer individuell begrenzten Selbstregulationsstärke aus, so sollte sich diese letztendlich limitierend auf die individuelle berufliche Leistungsfähigkeit auswirken. Im Dualen Hochschulstudium müssen die Studierenden nicht nur ihre berufspraktische, sondern auch ihre akademische Leistungsfähigkeit unter Beweis stellen. In der vorliegenden Studie wurden die Haupteffekte der Selbstregulationsstärke auf berufspraktische und akademische Leistungsindikatoren untersucht. Wir konnten zeigen, dass die individuelle Basiskapazität zur Selbstregulation in einer Stichprobe von 101 Studierenden der Dualen Hochschule Baden Württemberg (DHBW) Mannheim sowohl signifikante Zusammenhänge mit berufspraktischen als auch akademischen Leistungsindikatoren aufweist. Dies spricht dafür, dass die individuelle Basiskapazität zur Selbstregulation ein viel versprechendes Kriterium für Personalauswahlentscheidungen und Personalentwicklungsmaßnahmen ist.
ISK–Inventar Sozialer Kompetenzen von
Authors: Scherp Ella
Published: October 2010

Das Inventar Sozialer Kompetenzen (ISK) von Kanning (2009) ist der erste psychometrisch validierte Fragebogen zur Messung sozialer Kompetenzen im deutschen Sprachraum. Das ISK soll in der personaldiagnostischen Praxis und Forschung eingesetzt werden. Der vorliegende Beitrag beschreibt den theoretischen Hintergrund, Aufbau, Durchführung und psychometrische Gütekriterien des Verfahrens.
Evaluation eines Trainings zur Förderung sozialer Kompetenzen von Auszubildenden
Authors: Soucek Roman , Pospech Ivonne , Moser Klaus
Published: October 2010

Der vorliegende Beitrag diskutiert Ansatzpunkte eines Trainings zur Förderung sozialer Kompetenzen im Rahmen der beruflichen Erstausbildung und stellt ein konkretes Trainingsprogramm für Auszubildende vor. Das mehrtätige Training behandelt Themen der Kommunikation und Kooperation, die in vielfältigen Gruppenarbeiten und Rollenspielen vertieft und eingeübt werden. Ein integrierter Workshop mit Ausbildungsverantwortlichen zielt auf die Verbesserung der Rollenklarheit der Auszubildenden ab. Das Training wurde mit einem längsschnittlichen Untersuchungsdesign mit einer Vorerhebung und zwei Nacherhebungen evaluiert (N = 45). Insgesamt konnten Verbesserungen des Wissens und der Rollenklarheit festgestellt werden. Hinsichtlich der sozialen Kompetenzen ergab sich eine differenzierte Wirkung. Insbesondere gehen eine höhere Zunahme des Wissens sowie der Rollenklarheit mit hohen sozialen Kompetenzen einher. Insgesamt zeigt die Studie, dass die Verbesserung der Bedingungen sozial kompetenten Verhaltens (Wissen und Rollenklarheit) ein erfolgskritischer Faktor zur Förderung sozialer Kompetenzen ist.
Ultimate and practical limits of fluid-based mass detection with suspended microchannel resonators
Authors: Arlett J. L. , Roukes M. L.
Published: October 2010

Suspended microchannel resonators (SMRs) are an innovative approach to fluid-based microelectromechanical mass sensing that circumvents complete immersion of the sensor. By embedding the fluidics within the device itself, vacuum-based operation of the resonator becomes possible. This enables frequency shift-based mass detection with high quality factors, and hence sensitivity comparable to vacuum-based micromechanical resonators. Here we present a detailed analysis of the sensitivity of these devices, including consideration of fundamental and practical noise limits, and the important role of binding kinetics in sensing. We demonstrate that these devices show significant promise for protein detection. For larger, biologically-important targets such as rare whole virions, the required analysis time to flow sufficient sample through the sensor can become prohibitively long unless large parallel arrays of sensors or preconcentrators are employed.
Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser
Authors: Shaikh Nek M. , Tao Y. , Burdt R. A. , Yuspeh S. , Amin N. , Tillack M. S.
Published: October 2010

The temporal and spatial evolution of electron temperature and electron density from Sn plasma produced by a CO2 laser has been investigated in vacuum using spectroscopic methods. The plasma parameters were inferred by the Boltzmann plot method from experimentally observed line profiles of singly ionized Sn and Stark broadened profiles. At a laser intensity of 1010 W/cm2, electron temperature and density were measured to be within 1.13 eV to 0.53 eV and 5.3×1016 cm−3 to 1.4×1016 cm−3, respectively, for delay times between 200 ns and 1100 ns, and at distances up to 5 mm along the target normal. The results show the electron temperature and density from Sn plasma produced by a CO2 laser with wavelength of 10.6 μm to be lower than previously reported results using a 1064 nm laser in a similar parameter regime. The lower temperature in the region far away from the target surface confirms the smaller interaction region for CO2 laser as compared with that of neodymium-doped yttrium aluminum garnet laser.
A Tesla-pulse forming line-plasma opening switch pulsed power generator
Authors: Novac B. M. , Kumar R. , Smith I. R.
Published: October 2010

A pulsed power generator based on a high-voltage Tesla transformer which charges a 3.85 Ω/55 ns water-filled pulse forming line to 300 kV has been developed at Loughborough University as a training tool for pulsed power students. The generator uses all forms of insulation specific to pulsed power technology, liquid (oil and water), gas (SF6), and magnetic insulation in vacuum, and a number of fast voltage and current sensors are implemented for diagnostic purposes. A miniature (centimeter-size) plasma opening switch has recently been coupled to the output of the pulse forming line, with the overall system comprising the first phase of a program aimed at the development of a novel repetitive, table-top generator capable of producing 15 GW pulses for high power microwave loads. Technical details of all the generator components and the main experimental results obtained during the program and demonstrations of their performance are presented in the paper, together with a description of the various diagnostic tools involved. In particular, it is shown that the miniature plasma opening switch is capable of reducing the rise time of the input current while significantly increasing the load power. Future plans are outlined in the conclusions.
Nonisotropic spatiotemporal chaotic vibrations of the one-dimensional wave equation with a mixing transport term and general nonlinear boundary condition
Authors: Li Liangliang , Chen Yuanlong , Huang Yu
Published: October 2010

Nonisotropic spatiotemporal chaotic vibrations can happen for a linear wave equation with a mixing transport term on the unit interval and with a nonlinear van der Pol boundary condition at one end when the parameter(s) enters some regime [Chen et al., Int. J. Bifurcation Chaos Appl. Sci. Eng. 12, 535 (2002)]. In this paper, on the one hand, the equation with general nonlinear boundary conditions is considered. On the other hand, parameter range for the route to chaos is more precisely classified. The results obtained here generalize and sharpen those both in the above paper and the earlier work of [Li, L. L. and Huang, Y., J. Math. Anal. Appl. 361, 69 (2010)]. Two examples and their corresponding numerical simulations of chaotic space-time profiles are also illustrated.
High resolution, low hν photoelectron spectroscopy with the use of a microwave excited rare gas lamp and ionic crystal filters
Authors: Suga S. , Sekiyama A. , Funabashi G. , Yamaguchi J. , Kimura M. , Tsujibayashi M. , Uyama T. , Sugiyama H. , Tomida Y. , Kuwahara G. , Kitayama S. , Fukushima K. , Kimura K. , Yokoi T. , Murakami K. , Fujiwara H. , Saitoh Y. , Plucinski L. , Schneider C. M.
Published: October 2010

The need for not only bulk sensitive but also extremely high resolution photoelectron spectroscopy for studying detailed electronic structures of strongly correlated electron systems is growing rapidly. Moreover, easy access to such a capability in one’s own laboratory is desirable. Demonstrated here is the performance of a microwave excited rare gas (Xe, Kr, and Ar) lamp combined with ionic crystal filters (sapphire, CaF2, and LiF), which can supply three strong lines near the photon energy of hnyu hν=8.4, 10.0, and 11.6 eV, with the hν resolution of better than 600 μeV for photoelectron spectroscopy. Its performance is demonstrated on some materials by means of both angle-integrated and angle-resolved measurements.
Decreasing nanofluid droplet heating time with alternating magnetic fields
Authors: Fachini F. F. , Bakuzis A. F.
Published: October 2010

In this work we propose a new method to decrease the heating time of droplets. Our model considers the heating process of magnetic nanofluid droplet, which was taken to an ambient atmosphere at high temperature and with an alternating magnetic field. Analytical solutions were obtained in systems governed by Brownian and/or low-barrier Néel relaxation (superparamagnetic regime). The droplet heating time was shown to scale with the reciprocal of the square of frequency (1/f2) at the low frequency regime. The droplet heating time was calculated as function of frequency for different particle sizes, coating layers, and relaxation mechanisms.
Scrape-off layer reflectometer for Alcator C-Mod
Authors: Lau Cornwall , Hanson Greg , Wilgen John , Lin Yijun , Wukitch Steve
Published: October 2010

A swept-frequency X-mode reflectometer is being built for Alcator C-Mod to measure the scrape-off layer density profiles at the top, middle, and bottom locations in front of both the new lower hybrid launcher and the new ion cyclotron range of frequencies antenna. The system is planned to operate between 100 and 146 GHz at sweep rates from 10 μs to 1 ms, and will cover a density range of approximately 1016–1020 m−3 at B0=5–5.4 T. To minimize the effects of density fluctuations, both differential phase and full phase reflectometry will be employed. Design, test data, and calibration results of this electronics system will be discussed. To reduce attenuation losses, tallguide (TE01) will be used for most of the transmission line system. Simulations of high mode conversion in tallguide components, such as e-plane hyperbolic secant radius of curvature bends, tapers, and horn antennas will be shown. Experimental measurements of the total attenuation losses of these components in the lower hybrid waveguide run will also be presented.
Lateral drift and concentration instability in a suspension of bubbles induced by Marangoni stresses at zero Reynolds number
Authors: Narsimhan Vivek , Shaqfeh Eric S. G.
Published: October 2010

We report a concentration instability at zero Reynolds number created by hydrodynamically interacting bubbles with surfactant. This instability is driven by Marangoni stresses that force bubbles to migrate in directions perpendicular to gravity. We characterize the lateral motion of a single buoyant bubble when it is subject to a weak, low wavenumber disturbance velocity. We use this result to determine which mean flow wavevectors amplify concentration fluctuations in a dilute suspension. The suspension is linearly unstable at small horizontal wavenumbers by a mechanism similar to the concentration instabilities demonstrated in suspensions of sedimenting nonspherical or deformable particles.
Review of long period fiber gratings written by CO2 laser
Authors: Wang Yiping
Published: October 2010

This paper presents a systematic review of long period fiber gratings (LPFGs) written by the CO2 laser irradiation technique. First, various fabrication techniques based on CO2 laser irradiations are demonstrated to write LPFGs in different types of optical fibers such as conventional glass fibers, solid-core photonic crystal fibers, and air-core photonic bandgap fibers. Second, possible mechanisms, e.g., residual stress relaxation, glass structure changes, and physical deformation, of refractive index modulations in the CO2-laser-induced LPFGs are analyzed. Third, asymmetrical mode coupling, resulting from single-side laser irradiation, is discussed to understand unique optical properties of the CO2-laser-induced LPFGs. Fourthly, several pretreament and post-treatment techniques are proposed to enhance the efficiency of grating fabrications. Fifthly, sensing applications of the CO2-laser-induced LPFGs are investigated to develop various LPFG-based temperature, strain, bend, torsion, pressure, and biochemical sensors. Finally, communication applications of the CO2-laser-induced LPFGs are investigated to develop various LPFG-based band-rejection filters, gain equalizers, polarizers, and couplers.
Electronic structure and magnetic properties of Mn-doped ZnO nanotubes: An ab initio study
Authors: He A. L. , Wang X. Q. , Fan Y. Q. , Feng Y. P.
Published: October 2010

The electronic and magnetic properties of pure and Mn-doped armchair and zigzag ZnO nanotubes were studied using density functional theory with the generalized gradient approximation. The calculated results show that all of the pure ZnO nanotubes are nonmagnetic and have relatively uniform band gap of 1.66 eV at Γ-point. Both the armchair and zigzag ZnO nanotubes are found to be direct gap and the band gaps are almost independent of tubular structures. For the Mn-doped ZnO nanotubes, it is noted that the band gaps are influenced by three factors, doping concentration, diameter, and chirality of the tube, while the bond lengths between Zn and O and between Mn and O for these structures are only decided by the diameter of the nanotube. The magnetic moments, however, are independent of the chirality from comparison between armchair and zigzag Mn-doped ZnO nanotube, and mainly governed by the doping concentration and diameter of the nanotube. Furthermore, it is found that large magnetic moments appears in Mn-doped ZnO nanotubes, which are principally due to the hybridization between the O 2p and Mn 3d states by our analysis.
Calibration of a high resolution grating soft x-ray spectrometer
Authors: Magee E. W. , Dunn J. , Brown G. V. , Cone K. V. , Park J. , Porter F. S. , Kilbourne C. A. , Kelley R. L. , Beiersdorfer P.
Published: October 2010

The calibration of the soft x-ray spectral response of a large radius of curvature, high resolution grating spectrometer (HRGS) with a back-illuminated charge-coupled device detector is reported. The instrument is cross-calibrated for the 10–50 Å waveband at the Lawrence Livermore National Laboratory electron beam ion trap (EBIT) x-ray source with the EBIT calorimeter spectrometer. The HRGS instrument is designed for laser-produced plasma experiments and is important for making high dynamic range measurements of line intensities, line shapes, and x-ray sources.
Theoretical study of Al+–RG (RG=He–Rn)
Authors: Gardner Adrian M. , Gutsmiedl Kayla A. , Wright Timothy G. , Breckenridge W. H. , Chapman Chivone Y. N. , Viehland Larry A.
Published: October 2010

We present the results of CCSD(T) calculations on the full set of Al+–RG complexes (RG=He–Rn). Potential energy curves are calculated pointwise, employing the full counterpoise correction and basis sets of quadruple-ζ and quintuple-ζ quality, and then extrapolated to the complete basis set limit. Each curve has been employed to calculate rovibrational energy levels, from which spectroscopic parameters have been derived. These are compared to the available experimental data, and it is seen that there is excellent agreement with the values obtained from both Rydberg state extrapolations and high-resolution laser-induced fluorescence studies. Finally, we have also used our potentials to calculate transport coefficients for Al+ moving through a bath of RG.
Construction and testing of the instrument for neutron holographic study at the Budapest Research Reactor
Authors: Markó Márton , Szakál Alex , Török Gyula , Cser László
Published: October 2010

Neutron scattering device dedicated to neutron holography experiments is described. The device is operating at a constant wavelength prepared by a double focusing monochromator. It is equipped by highly efficient shielding, proper collimator, Eulerian cradle, monitor detector, gamma-ray, and neutron detectors as well. Relevant software serves as control for the measurement and data collection. The harmonized application of the components enumerated above makes our device extremely efficient and unparalleled. Two atomic resolution neutron holographic experiments carried out illustrate the efficiency and power of the instrument.
Application of beam emission spectroscopy to NBI plasmas of Heliotron J
Authors: Kobayashi S. , Kado S. , Oishi T. , Kagawa T. , Ohshima S. , Mizuuchi T. , Nagasaki K. , Yamamoto S. , Okada H. , Minami T. , Murakami S. , Lee H. Y. , Minami T. , Nakamura Y. , Hanatani K. , Konoshima S. , Takeuchi M. , Toushi K. , Sano F.
Published: October 2010

This paper describes the application of the beam emission spectroscopy (BES) to Heliotron J, having the nonsymmetrical helical-magnetic-axis configuration. The spectral and spatial profile of the beam emission has been estimated by the numerical calculation taking the collisional excitation processes between plasmas (electrons/ions) and beam atoms. Two sets of the sightlines with good spatial resolution are presented. One is the optimized viewing chords which have 20 sightlines and observe the whole plasma region with the spatial resolution Δρ less than ±0.055 using the newly designed viewing port. The other is 15 sightlines from the present viewing port of Heliotron J for the preliminary measurement to discuss the feasibility of the density fluctuation measurement by BES. The beam emission has been measured by a monochromator with a CCD camera. A good consistency has been obtained between the spectral profiles of the beam emission measured by the monochromator and the beam emission spectrum deduced by the model calculation. An avalanche photodiode with an interference filter system was also used to evaluate the signal-to-noise (S/N) ratio of the beam emission in the present experimental setup. The modification of the optical system is being planned to improve the S/N ratio, which will enable us to estimate the density fluctuation in Heliotron J.
On the role of dissipation on the Casimir–Polder potential between molecules in dielectric media
Authors: Rodriguez Justo J. , Salam A.
Published: October 2010

An expression for the Casimir–Polder potential between molecules in a homogeneous dispersive and absorptive dielectric medium is derived. The effect of retardation on the interaction energy is discussed by examining the wave-zone and nonretarded limits of the potential. Unlike Lifshitz theory, the interaction energy is not derived from the potential between macroscopic bodies. In this work, a Green function that explicitly accounts for absorption in the medium is obtained. This function leads to possible dissipation effects and presents a near-zone form that vanishes in the limit of nonabsorptive medium. Employing a two-level model, it is shown that the retarded van der Waals dispersion potential in a medium may become repulsive as a consequence of absorption by the medium. It is suggested that the repulsive dispersion force may delay precipitation of nonpolar molecules from a dielectric solvent or even inhibit chemical reaction between them.
Harmonic oscillator in twisted Moyal plane: Eigenvalue problem and relevant properties
Authors: Hounkonnou Mahouton Norbert , Samary Dine Ousmane
Published: October 2010

This paper reports on a study of a harmonic oscillator (ho) in the twisted Moyal space, in a well defined matrix basis, generated by the vector fields Xa=eaμ(x)∂μ=(δaμ+ωabμxb)∂μ, which induce a dynamical star product. The usual multiplication law can be hence reproduced in the ωabμ null limit. The star actions of creation and annihilation functions are explicitly computed. The ho states are infinitely degenerated with energies depending on the coordinate functions.
In situ ultrahigh vacuum transmission electron microscopy study of quasi-one-dimensional island decay on isotropic Ge(001) surface
Authors: Li Zhi-Peng , Tok Eng Soon , Foo Yong Lim
Published: October 2010

In situ ultrahigh vacuum transmission electron microscopy was employed to observe the dynamics of both the coalescence and decay of two-dimensional Fe13Ge8 islands on an atomically smooth Ge(001) surface. Quasi-one-dimensional (1D) island decay behavior was observed on the isotropic Ge(001) surface where annealing caused the islands to shrink significantly faster in one direction. The shrinkage in the perpendicular direction was minimal in comparison. This is contrary to Ostwald ripening for isotropic surfaces, as well as for the quasi-1D island decay model for anisotropic surfaces. During annealing, this island decay behavior occurred by the attachment/detachment limiting mechanism, which is based on an analysis of adatom concentration differences. Therefore, this quasi-1D island decay process is driven by adatom concentration differences between coalescing and decaying islands. Island decay occurs along the large diffusive flux channel between islands and is affected by the local environment.
Self-consistent electrothermal Monte Carlo simulation of single InAs nanowire channel metal-insulator field-effect transistors
Authors: Sadi Toufik , Thobel Jean-Luc , Dessenne François
Published: October 2010

Electron transport and self-heating effects are investigated in metal-insulator field-effect transistors with a single InAs nanowire channel, using a three-dimensional electrothermal Monte Carlo simulator based on finite-element meshing. The model, coupling an ensemble Monte Carlo simulation with the solution of the heat diffusion equation, is carefully calibrated with data from experimental work on these devices. This paper includes an electrothermal analysis of the device basic output characteristics as well the microscopic properties of transport, including current-voltage curves, heat generation and temperature distributions, and electron velocity profiles. Despite the low power dissipation, results predict significant peak temperatures, due to the high power density levels and the poor thermal management in these structures. The extent of device self-heating is shown to be strongly dependent on both device biasing configuration as well as geometry.
Fluorescence quenching of rhodamine-6G in Au nanocomposite polymers
Authors: Karthikeyan B.
Published: October 2010

Nanocomposite polymers are gaining interest because of their ease of preparation and device applications. In this report, synthesis of Au-polyvinyl alcohol nanocomposite and rhodamine-6G doped Au-polyvinyl alcohol nanocomposite polymer films which are prepared at room temperature have been reported. The role of nanosized gold on fluorescence properties of rhodamine-6G has been analyzed. Steady state fluorescence studies show that the nanoparticles quench the fluorescence of rhodamine-6G. Fluoresence quenching were analyzed using all possible mechanisms like Förster resonant energy transfer, nanometal surface energy transfer and electron transfer to metallic conduction bands. Time resolved fluorescence studies reveal that the decay rate changes because of the addition of Au nanoparticles and also depends on the size of the nanoparticles.
High-voltage pulsed generator for dynamic fragmentation of rocks
Authors: Kovalchuk B. M. , Kharlov A. V. , Vizir V. A. , Kumpyak V. V. , Zorin V. B. , Kiselev V. N.
Published: October 2010

A portable high-voltage (HV) pulsed generator has been designed for rock fragmentation experiments. The generator can be used also for other technological applications. The installation consists of low voltage block, HV block, coaxial transmission line, fragmentation chamber, and control system block. Low voltage block of the generator, consisting of a primary capacitor bank (300 μF) and a thyristor switch, stores pulse energy and transfers it to the HV block. The primary capacitor bank stores energy of 600 J at the maximum charging voltage of 2 kV. HV block includes HV pulsed step up transformer, HV capacitive storage, and two electrode gas switch. The following technical parameters of the generator were achieved: output voltage up to 300 kV, voltage rise time of ∼50 ns, current amplitude of ∼6 kA with the 40 Ω active load, and ∼20 kA in a rock fragmentation regime (with discharge in a rock-water mixture). Typical operation regime is a burst of 1000 pulses with a frequency of 10 Hz. The operation process can be controlled within a wide range of parameters. The entire installation (generator, transmission line, treatment chamber, and measuring probes) is designed like a continuous Faraday’s cage (complete shielding) to exclude external electromagnetic perturbations.
Optical polarization anisotropy of tensile strained InGaN/AlInN quantum wells for TM mode lasers
Authors: Dang Po-Yuan , Wu Yuh-Renn
Published: October 2010

In this paper, we discuss the optical characteristics and polarization anisotropy of a tensile strained polar c-plane InGaN/AlInN quantum well. We found that if the quantum well is under the tensile strain, the |Z⟩-like state will be lifted up so that the emitted light will be TM mode. In addition, with a particular aluminum composition of the AlInN alloy as the barrier for the tensile strained InGaN quantum well, it is possible to reduce quantum-confined Stark effect. The self-consistent Poisson and 6×6 k⋅p Schrödinger solver has been used for studying light emitting characteristics. Our results show that the tensile strained InGaN quantum well on AlInN barrier has much larger optical gain and lower threshold carrier density compared to the conventional InGaN/GaN system, and it has a potential to be TM light source for edge emitting laser diodes with the photonic crystal cavity made by nanorod arrays.
Synthesis, magnetic properties, and neutron diffraction study of the complex perovskites R(Cu3−xMnx)Mn4O12 (R=Pr, Nd and x=1,2)
Authors: Retuerto M. , Martínez-Lope M. J. , Sánchez-Benítez J. , García-Hernández M. , Fernández-Díaz M. T. , Alonso J. A.
Published: October 2010

The new complex perovskites of formula R(Cu3−xMnx)Mn4O12 (R=Pr, Nd and x=1,2) have been prepared. The partial replacement of Cu2+ by Mn3+ cations does not involve a change in symmetry from that of the parent compounds RCu3Mn4O12, presenting a cubic structure with space group Im3¯. The Mn3+ introduced at the square-planar 6b site promotes the valence mixing of Mn3+ and Mn4+ ions at the octahedral 8c site, leading to an increase in the bonding distances in the MnO6 octahedron and a slight decrease in the distances in the CuO4 polyhedron. All the compounds present a spontaneous increase in the magnetization below TC, typical of ferro- or ferrimagnetic materials. Due to the increasing content of Mn3+ at the 8c sites, some Mn–Mn exchange interactions switch from ferromagnetic (FM) to antiferromagnetic (AFM), weakening the overall FM exchange interactions and decreasing TC and MS. Neutron powder diffraction (NPD) data indicate that both sublattices (square-planar and octahedral) show a parallel arrangement of the magnetic moments.
Reset dynamics and latching in niobium superconducting nanowire single-photon detectors
Authors: Annunziata Anthony J. , Quaranta Orlando , Santavicca Daniel F. , Casaburi Alessandro , Frunzio Luigi , Ejrnaes Mikkel , Rooks Michael J. , Cristiano Roberto , Pagano Sergio , Frydman Aviad , Prober Daniel E.
Published: October 2010

We study the reset dynamics of niobium (Nb) superconducting nanowire single-photon detectors (SNSPDs) using experimental measurements and numerical simulations. The numerical simulations of the detection dynamics agree well with experimental measurements, using independently determined parameters in the simulations. We find that if the photon-induced hotspot cools too slowly, the device will latch into a dc resistive state. To avoid latching, the time for the hotspot to cool must be short compared to the inductive time constant that governs the resetting of the current in the device after hotspot formation. From simulations of the energy relaxation process, we find that the hotspot cooling time is determined primarily by the temperature-dependent electron-phonon inelastic time. Latching prevents reset and precludes subsequent photon detection. Fast resetting to the superconducting state is, therefore, essential, and we demonstrate experimentally how this is achieved. We compare our results to studies of reset and latching in niobium nitride SNSPDs.
Sensitive dependence on parameters
Authors: Misiurewicz Michał
Published: October 2010

For a family of dynamical systems we define sensitive dependence on parameters in a way resembling Guckenheimer’s definition of sensitive dependence on initial conditions. While sensitive dependence on initial conditions tells us that if we know the initial condition only approximately then we cannot make deterministic predictions, sensitive dependence on parameters tells us that if we know the parameter value only approximately then we cannot make statistical predictions. We show that the family of logistic maps has sensitive dependence on parameters. Moreover, the long-time response of the system to the change of the parameter is practically independent of the immediate response.
Band offsets determination and interfacial chemical properties of the Al2O3/GaSb system
Authors: Geppert I. , Eizenberg M. , Ali A. , Datta S.
Published: October 2010

Band offsets of the Al2O3/GaSb system and various surface passivation treatments of the GaSb substrate by HCl, NH4OH, and (NH4)2S solutions were investigated by x-ray photoelectron spectroscopy. The extracted conduction and valence band offsets values of Al2O3 relative to GaSb are 2.4±0.1 eV and 3.4±0.2 eV, respectively. The presence of Ga–O and Sb–O bonds was detected after NH4OH surface treatment. In contrast, (NH4)2S and HCl solutions inhibit the Sb oxide formation. The lowest amount of Ga–O bands was obtained for (NH4)2S passivation. These results correlate with capacitance-voltage (C-V) measurements of Pd–Au/Al2O3/GaSb stacks which yielded the best characteristics for the S-based passivation.
A gentler approach to RNEMD: Nonisotropic velocity scaling for computing thermal conductivity and shear viscosity
Authors: Kuang Shenyu , Gezelter J. Daniel
Published: October 2010

We present a new method for introducing stable nonequilibrium velocity and temperature gradients in molecular dynamics simulations of heterogeneous systems. This method extends earlier reverse nonequilibrium molecular dynamics (RNEMD) methods which use momentum exchange swapping moves. The standard swapping moves can create nonthermal velocity distributions and are difficult to use for interfacial calculations. By using nonisotropic velocity scaling (NIVS) on the molecules in specific regions of a system, it is possible to impose momentum or thermal flux between regions of a simulation while conserving the linear momentum and total energy of the system. To test the method, we have computed the thermal conductivity of model liquid and solid systems as well as the interfacial thermal conductivity of a metal-water interface. We find that the NIVS-RNEMD improves the problematic velocity distributions that develop in other RNEMD methods.
Structural, electronic, and optical aspects of Cr doping of the Bi4Ge3O12: An ab initio study
Authors: Lima A. F. , Lalic M. V.
Published: October 2010

Ab initio calculations based on density functional theory have been employed to study energetic, structural, electronic, and optical properties of Cr doped Bi4Ge3O12 (BGO). Two possible accommodations of Cr impurity have been taken into account: at the Ge (Cr4+) and the Bi (Cr3+) substitution site. For each accommodation the local structure around the Cr has been determined, and in the Cr3+ case the Cr off-site displacement was analyzed. The Cr d-states are positioned at the bottom of the conduction band and within the gap in form of two deeplike (Cr4+) and shallowlike (Cr3+) bands, exhibiting magnetic moments of +1.58 μB and −2.44 μB, respectively. The Cr dominated part of absorption spectrum is calculated and analyzed in terms of Cr band arrangement. Comparison with the experimental BGO:Cr absorption spectrum suggests that it consists of both Cr3+ and Cr4+ contributions, indicating the Cr simultaneous presence at both substitution sites.
Cohomology of line bundles: Proof of the algorithm
Authors: Roschy Helmut , Rahn Thorsten
Published: October 2010

We present a proof of the algorithm for computing line bundle valued cohomology classes over toric varieties conjectured by Blumenhagen et al. [e-print arXiv:1003.5217] and suggest a kind of Serre duality for combinatorial Betti numbers that we observed when computing examples.
Petrov type D pure radiation fields of Kundt’s class
Authors: De Groote Liselotte , Van den Bergh Norbert , Wylleman Lode
Published: October 2010

We present all Petrov type D pure radiation space-times, with or without cosmological constant, with a shear-free, nondiverging geodesic principal null congruence. We thus completely solve the problem of aligned Petrov type D pure radiation fields: either these are Robinson–Trautman space-times and are all explicitly known or they belong to the Kundt family, for which so far only isolated examples existed in the literature.
Tilting of the spin orientation induced by Rashba effect in ferromagnetic metal layer
Authors: Pi Ung Hwan , Won Kim Kee , Bae Ji Young , Lee Sung Chul , Cho Young Jin , Kim Kwang Seok , Seo Sunae
Published: October 2010

We devised a method to measure the virtual magnetic field induced by Rashba effect in ferromagnetic metal layer. Transverse Rashba magnetic field makes the magnetization direction tilted out of the easy axis, which could be detected by the change in anomalous hall resistances. Through a specified measurement of the second harmonics of the hall resistance, the Rashba field could be obtained with high sensitivity even at low current regime. The results are compared with the prior reports based on the measurement of the transverse field required for the nucleation of reversed domain.
Deep-ultraviolet photodetectors from epitaxially grown NixMg1−xO
Authors: Mares J. W. , Boutwell R. C. , Wei M. , Scheurer A. , Schoenfeld W. V.
Published: October 2010

Deep-ultraviolet (DUV) photodetectors were fabricated from high quality NixMg1−xO epitaxially grown by plasma-assisted molecular beam epitaxy on an approximately lattice matched MgO ⟨100⟩ substrate. A mid-range Ni composition (x=0.54) NixMg1−xO film was grown for DUV (λpeak<300 nm) photoresponse and the film was characterized by reflected high-energy electron diffraction, Rutherford backscattering spectroscopy, x-ray diffraction, and optical transmission measurements. Photoconductive detectors were then fabricated by deposition of symmetric interdigitated contacts (10 nm Pt/150 nm Au) with contact separations of 5, 10, and 15 μm. The detectors exhibited peak responsivities in the DUV (λpeak≈250 nm) as high as 12 mA/W, low dark currents (Idark<25 nA), and DUV:visible rejection ratio of approximately 800:1.
Concentration quenching of electroluminescence in neat Ir(ppy)3 organic light-emitting diodes
Authors: Zhang Y. Q. , Zhong G. Y. , Cao X. A.
Published: October 2010

We studied concentration quenching of electroluminescence (EL) in organic light-emitting diodes with a neat fac-tris(2-phenylpyridinato-N, C2′) iridium (III) [Ir(ppy)3] emitting layer of different thicknesses sandwiched between electron and hole blocking layers. The intensity of the green emission decreased rapidly with increasing Ir(ppy)3 thickness and was reversely correlated with the tail band emission. The overall light output power reached the minimum at 4 nm, and attained a saturated value for Ir(ppy)3 thicker than 6 nm. These results are interpreted as evidence that concentration quenching in Ir(ppy)3 originates from both short and long-range energy transfer between excited and ground states of molecules. The EL quenching magnitude was found to be independent of the injection current, indicating that biexcitonic annihilation plays a minor role.
Structure and stability of thin water films on quartz surfaces
Authors: Chen Yun-Wen , Cheng Hai-Ping
Published: October 2010

We investigated thin water films on quartz (0001) surfaces using first-principles density functional theory calculations. Interfacial structure and energetics were studied through a layer-by-layer deposition. From monolayer to multilayer, the low energy state configurations and adsorption sites show a transition due to formation of a highly stable bilayer membranelike structure. The water adsorption energy on a quartz surface coated by this membrane is of typical hydrogen bond strength for both dry and fully hydroxylated surfaces. The interactions between the surface and the water films are short-ranged due to shielding of the bilayer.
Optically-addressed two-terminal multicolor photodetector
Authors: Steenbergen E. H. , DiNezza M. J. , Dettlaff W. H. G. , Lim S. H. , Zhang Y.-H.
Published: October 2010

A two-terminal multicolor photodetector that is most advantageous for greater than two bands is proposed. This two-terminal design is particularly significant for focal plane arrays as it maximizes the fill factor and simplifies the readout integrated circuits. Individual color detection is realized with appropriate optical biasing. This concept is demonstrated experimentally using a three-color photodetector and biasing light emitting diodes. The measured linear dynamic range is greater than four orders of magnitude, making it a practical device for a broad range of applications.
Capturing a DNA duplex under near-physiological conditions
Authors: Zhang Huijuan , Xu Wei , Liu Xiaogang , Stellacci Francesco , Thong John T. L.
Published: October 2010

We report in situ trapping of a thiolated DNA duplex with eight base pairs into a polymer-protected gold nanogap device under near-physiological conditions. The double-stranded DNA was captured by electrophoresis and covalently attached to the nanogap electrodes through sulfur-gold bonding interaction. The immobilization of the DNA duplex was confirmed by direct electrical measurements under near-physiological conditions. The conductance of the DNA duplex was estimated to be 0.09 μS. We also demonstrate the control of DNA dehybridization by heating the device to temperatures above the melting point of the DNA.
Microplasma-induced surface engineering of silicon nanocrystals in colloidal dispersion
Authors: Švrček V. , Mariotti D. , Kondo M.
Published: October 2010

We report on an atmospheric-pressure dc microplasma that can be used to passivate silicon nanocrystals (SiNCs) in ethanol and that stabilizes their optoelectronic properties. We show that microplasma processing enhances the SiNCs photoluminescence intensity by factor of more than ten times and ∼80 nm redshift of its maximum. The microplasma induces the replacement of hydrogen terminations with hydroxyl-/organic-based bonds. The resulting surface characteristics are responsible for the formation of conductive and stable SiNCs self-organized assemblies extending over 0.5 mm after dewetting on a substrate.
Ferroelectric property improvement of poly(vinylidene fluoride/trifluoroethylene) polymer exposed to a plasma ambient
Authors: Park C. H. , Lee Kwang H. , Ha Taewoo , Kim Jae Hoon , Im Seongil , Yun Jungheum , Lee Gun Hwan
Published: October 2010

We report a dramatic property improvement of ferroelectric polymer poly(vinylidene fluoride/trifluoroethylene) [P(VDF-TrFE)] upon exposure to a plasma ambient. The P(VDF-TrFE) layer for typical nonvolatile memory devices shows only ∼6.5 μC/cm2 and 0.55 MV/cm for its remnant polarization and coercive field, respectively, but the values increase to ∼13 μC/cm2 and ∼1 MV/cm after an optimum period of plasma exposure. Our infrared measurement confirms that the plasma energy creates many CC double bonds in the polymer chain while removing some of CF bonds, which are responsible for ferroelectric polarization. Nevertheless, the strengthened polymer can incorporate higher applied field, thereby aligning electric dipoles much better.
Understanding structure-property relationship of resistive switching oxide thin films using a conical filament model
Authors: Kim Kyung Min , Lee Min Hwan , Kim Gun Hwan , Song Seul Ji , Seok Jun Yeong , Yoon Jung Ho , Hwang Cheol Seong
Published: October 2010

The relations between the reset current IR, room temperature filament resistance R0, and third harmonic coefficient B0 were evaluated by a conical filament model. It was found that IR∼1/R0 when the filament is either very weak, where the filament is more conical, or quite strong, where the filament is more cylindrical. The physical implication of the B0 was also understood from the materials properties. The coherence between the model expectations for the bulkier conical filaments, typically found in TiO2, and the more random-network like filaments, typically found in NiO, suggests a common switching mechanism works in both materials.
rf auto-oscillations in antiferromagnetically coupled layers with different coupling strengths
Authors: Seki Takeshi , Tomita Hiroyuki , Shinjo Teruya , Suzuki Yoshishige
Published: October 2010

rf auto-oscillation induced by spin-transfer torque was investigated in Fe/Cr/Fe systems that had antiferromagnetically coupled Fe layers. As the coupling strength increased, the generation linewidth (Δf) reduced remarkably whereas the oscillation frequency (f) and the onset current of the auto-oscillation increased. The strong antiferromagnetic coupling led to less variation in f depending on the bias current. These results indicate that the antiferromagnetic coupling allows us to reduce Δf and to control the nonlinearity of the rf auto-oscillation.
Mode-coupling Cerenkov sum-frequency-generation in a multimode planar waveguide
Authors: Chen Changdong , Su Jie , Zhang Yong , Xu Ping , Hu Xiaopeng , Zhao Gang , Liu Yanhua , Lv Xinjie , Zhu Shining
Published: October 2010

We present experimental and theoretical studies of the mode-coupling Cerenkov sum-frequency radiations in a multimode LiNbO3 planar waveguide. The radiations result from the coupling of different guided modes of the fundamental wave, which have the same optical frequencies but different propagation constants. At the same time, scattering-involved Cerenkov sum-frequency-generation was also observed and discussed. Our theoretical predictions are in well accordance with the experimental results.
Aggregate formation and its effect on (opto)electronic properties of guest-host organic semiconductors
Authors: Shepherd Whitney E. B. , Platt Andrew D. , Hofer David , Ostroverkhova Oksana , Loth Marsha , Anthony John E.
Published: October 2010

We quantify guest molecule aggregation and its effect on the photoconductive properties of guest-host thin films, depending on the guest concentration and host material. A high-performance anthradithiophene (ADT) derivative served as a guest, while functionalized benzothiophene (BTBTB) and polymethylmethacrylate (PMMA) were chosen as hosts. Aggregates exhibited redshifted optical absorption and photoluminescence (PL) spectra, as well as reduced PL quantum yields. Propensity toward guest aggregation differed for PMMA and BTBTB hosts. Photocurrents dramatically increased as the percentage of aggregated guest molecules increased due to considerably higher charge carrier mobility in the aggregates. At low guest concentrations, BTBTB films outperformed PMMA films.
Interface effects on an ultrathin Co film in multilayers based on the organic semiconductor Alq3
Authors: Sidorenko A. A. , Pernechele C. , Lupo P. , Ghidini M. , Solzi M. , De Renzi R. , Bergenti I. , Graziosi P. , Dediu V. , Hueso L. , Hindmarch A. T.
Published: October 2010

The effect of the AlOx barrier thickness on magnetic and morphological properties of Ta/Co/(AlOx)/Alq3/Si hybrid structures was systematically studied by means of atomic force microscopy, superconducting quantum interference device magnetometry, and nuclear magnetic resonance (NMR). All used techniques pointed out that the barrier thickness of 2 nm is required to obtain a magnetically good cobalt layer on top of Alq3. C59o NMR measurements revealed that the AlOx barrier gives rise to the formation of an interface layer with “defective” cobalt favoring growth of “bulk” cobalt with good magnetic properties.
N 1s photoelectron angular distributions from fixed-in-space NO2 molecules: Stereodynamics and symmetry considerations
Authors: Yamazaki Masakazu , Adachi Jun-ichi , Kimura Yasuyuki , Stener Mauro , Decleva Piero , Yagishita Akira
Published: October 2010

Angular distributions of N 1s photoelectrons from fixed-in-space NO2 molecules have been measured over the energy region of shape resonance and above. A multiple-coincidence velocity-map imaging technique for observation of molecular frame photoelectron angular distributions (MF-PADs) has been extended to nonlinear molecular targets. Density functional theory calculations have also been conducted to elucidate the photoionization dynamics and shape resonance in the N 1s photoionization of NO2. Results show that the N 1s MF-PADs exhibit strong shape variation as a function of both photoelectron kinetic energy and symmetries of final states, whereas asymmetry parameters of laboratory frame PADs show a local minimum around the shape resonance region and increase monotonically as the photon energy increases. Over the shape resonance, the spatial shape of the photoelectron wave function with b2-symmetry closely resembles that of 5b2∗ unoccupied molecular orbital of NO2, although the MF-PAD pattern for b2-symmetry does not correspond directly to the 5b2∗ orbital shape. At higher kinetic energy of 90 eV, MF-PADs become less structured, but still show a significant dependence on the symmetry of final states.