bluuebunny/crossref_metadata_2025 huggingface dataset:
Expanding the Margins of Identity: A Critique of Marginalization in a Globalized World
Authors: Kunst Jonas R. , Sam David L.
Published: July 2013

In an increasingly globalized world, global culture may constitute an alternative cultural resource, especially for members of ethnic minority groups who have often been described as marginalized in acculturation research. In the present study, we investigated the role that global identity may play for the self-concept and the psychological and sociocultural adaptation of ethnic minority members, especially those who score high on marginalization. We explored these relationships in 848 European Muslim minority members. Marginalized participants showed lower ethnic identity but the same or even stronger global identity compared with nonmarginalized participants. No difference in sociocultural adaptation was observed between nonmarginalized participants and marginalized individuals, when the latter expressed strong global identification. Moreover, in terms of ethnic discrimination, increasing one’s global identity was related to better psychological adaptation compared with increasing one’s ethnic identity, although coefficients remained small. Based on our results, we, in line with other researchers, argue for a reevaluation and differentiation of the concept “marginalization,” which has mostly been viewed in negative terms. Additional available cultural resources, such as global identity, may offset the negative relation between marginalization and adaptation and may mediate the effect of ethnic discrimination on psychological adaptation.
Forcing of anthropogenic aerosols on temperature trends of the sub-thermocline southern Indian Ocean
Authors: Cowan Tim , Cai Wenju , Purich Ariaan , Rotstayn Leon , England Matthew H.
Published: July 2013

In the late twentieth century, the sub-thermocline waters of the southern tropical and subtropical Indian Ocean experienced a sharp cooling. This cooling has been previously attributed to an anthropogenic aerosol-induced strengthening of the global ocean conveyor, which transfers heat from the subtropical gyre latitudes toward the North Atlantic. From the mid-1990s the sub-thermocline southern Indian Ocean experienced a rapid temperature trend reversal. Here we show, using climate models from phase 5 of the Coupled Model Intercomparison Project, that the late twentieth century sub-thermocline cooling of the southern Indian Ocean was primarily driven by increasing anthropogenic aerosols and greenhouse gases. The models simulate a slow-down in the sub-thermocline cooling followed by a rapid warming towards the mid twenty-first century. The simulated evolution of the Indian Ocean temperature trend is linked with the peak in aerosols and their subsequent decline in the twenty-first century, reinforcing the hypothesis that aerosols influence ocean circulation trends.
Molecule-displacive ferroelectricity in organic supramolecular solids
Authors: Ye Heng-Yun , Zhang Yi , Noro Shin-ichiro , Kubo Kazuya , Yoshitake Masashi , Liu Zun-Qi , Cai Hong-Ling , Fu Da-Wei , Yoshikawa Hirofumi , Awaga Kunio , Xiong Ren-Gen , Nakamura Takayoshi
Published: July 2013

Ferroelectricity is essential to many forms of current technology, ranging from sensors and actuators to optical or memory devices. In this circumstance, organic ferroelectrics are of particular importance because of their potential application in tomorrow's organic devices and several pure organic ferroelectrics have been recently developed. However, some problems, such as current leakage and/or low working frequencies, make their application prospects especially for ferroelectric memory (FeRAM) not clear. Here, we describe the molecule-displacive ferroelectricity of supramolecular adducts of tartaric acid and 1,4-diazabicyclo[2.2.2]octane N,N′-dioxide. The adducts show large spontaneous polarization, high rectangularity of the ferroelectric hysteresis loops even at high operation frequency (10 kHz) and high performance in polarization switching up to 1 × 106 times without showing fatigue. It opens great perspectives in terms of applications, especially in organic FeRAM.
Ultrafast dynamics of liquid water: Frequency fluctuations of the OH stretch and the HOH bend
Authors: Imoto Sho , Xantheas Sotiris S. , Saito Shinji
Published: July 2013

Frequency fluctuations of the OH stretch and the HOH bend in liquid water are reported from the third-order response function evaluated using the TTM3-F potential for water. The simulated two-dimensional infrared spectra of the OH stretch are similar to previously reported theoretical results. The present study suggests that the frequency fluctuation of the HOH bend is faster than that of the OH stretch. The ultrafast loss of the frequency correlation of the HOH bend is due to the strong couplings with the OH stretch as well as the intermolecular hydrogen bond bend.
(Pre-)Hilbert spaces in twistor quantization
Authors: Deguchi Shinichi , Note Jun-ichi
Published: July 2013

In twistor theory, the canonical quantization procedure, called twistor quantization, is performed with the twistor operators represented as $\hat{Z}^{A}=Z^{A}\;\!(\in \mathbb{C})$ẐA=ZA(∈C) and $\hat{\bar{Z}}_{A} =-\partial /\partial Z^{A}$Z̄̂A=−∂/∂ZA. However, it has not been clarified what kind of function spaces this representation is valid in. In the present paper, we intend to find appropriate (pre-)Hilbert spaces in which the above representation is realized as an adjoint pair of operators. To this end, we define an inner product for the helicity eigenfunctions by an integral over the product space of the circular space S1 and the upper half of projective twistor space. Using this inner product, we define a Hilbert space in some particular case and indefinite-metric pre-Hilbert spaces in other particular cases, showing that the above-mentioned representation is valid in these spaces. It is also shown that only the Penrose transform in the first particular case yields positive-frequency massless fields without singularities, while the Penrose transforms in the other particular cases yield positive-frequency massless fields with singularities.
Finite size line broadening and superradiance of optical transitions in two dimensional long-range ordered molecular aggregates
Authors: Müller Mathias , Paulheim Alexander , Eisfeld Alexander , Sokolowski Moritz
Published: July 2013

The width and asymmetry of the line shape of the optical transition of a sample of two dimensional (2D) molecular J-aggregates was found to be related to a finite-size effect. The 2D aggregates were domains of the ordered monolayer of the fluorescent dye molecule 3,4,9,10-perylenetetracarboxylic acid dianhydride on a KCl(100) surface. Fluorescence and fluorescence excitation (FLE) spectra were measured as a function of temperature. The system shows a pronounced superradiant emission which yields additional information on the number of coherently coupled molecules participating in the emission. From calculations of the spectra within the tight binding model we find that the finite size of the 2D ordered domains of about N = 7 × 7 molecules, in combination with a Poissonian domain-size distribution, explains the line profile. Line broadening mechanisms due to site disorder or thermal effects – although not excludable straightaway – are not needed to explain the observed FLE line profile. This yields insight into the important, but so far not well understood, relation between the line profile and the size of ordered molecular aggregates.
One- and two-dimensional photo-imprinted diffraction gratings for manipulating terahertz waves
Authors: Chatzakis Ioannis , Tassin Philippe , Luo Liang , Shen Nian-Hai , Zhang Lei , Wang Jigang , Koschny Thomas , Soukoulis C. M.
Published: July 2013

Emerging technology based on artificial materials containing metallic structures has raised the prospect for unprecedented control of terahertz waves. The functionality of these devices is static by the very nature of their metallic composition, although some degree of tunability can be achieved by incorporating electrically biased semiconductors. Here, we demonstrate a photonic structure by projecting the optical image of a metal mask onto a thin GaAs substrate using a femtosecond pulsed laser source. We show that the resulting high-contrast pattern of photo-excited carriers can create diffractive elements operating in transmission, potentially providing a route to terahertz components with reconfigurable functionality.
A ray tracing study of shock leakage in a model supersonic jet
Authors: Shariff Karim , Manning Ted A.
Published: July 2013

Recent work has described screech noise from a supersonic jet as being due to leakage of a wave that is otherwise trapped in the jet's interior. In that work, the simplest of many techniques used is ray tracing for a single shear-layer modeled as a row of Stuart vortices. In the present work, a lower row of vortices is added to form a plane jet. Instead of plotting ray paths, a technique of visualization analogous to streaklines is used that better corresponds to instantaneous density fields as observed, for instance, by the Schlieren method. This produces striking images that show leakage of waves at each internal reflection resulting in a row of acoustic sources as envisioned since the 1950s. However, the sources are not isotropic and each has a zone of silence in the downstream direction. Leakage creates a fold in the wave pattern internal to the jet which leads to fine scale features. Reported experiments have also observed fine scale features (described as splitting) in the shock-cell pattern; they may be related to those observed here. Internally reflected rays also undergo a diffusive process as they propagate down the jet. In particular, each successive internal reflection at an unsteady shear-layer scatters rays along a wider range of wave angle and makes them more susceptible to leakage at the next reflection. It also causes more downstream directivity for the more downstream sources. An important result is that as the Mach number Mj is varied, maxima in leakage rate and mean acoustic amplitude occur at (near) resonances between the Mach-wave and shear-layer periods. Maxima in sound pressure level versus Mj have also been reported for laboratory round jets. Finally, as the shear-layer thickness is increased, a minimum in the rate of leakage (correlated with a minimum in radiation amplitude) occurs due to the competing effects of increased shear-layer penetration versus reduced eddy passage frequency.
Path integral Monte Carlo study of quantum-hard sphere solids
Authors: Sesé Luis M.
Published: July 2013

A path integral study of the fcc, hcp, and bcc quantum hard-sphere solids is presented. Ranges of densities within the interval of reduced de Broglie wavelengths $0.2 \le \lambda _B^* \le 0.8$0.2≤λB*≤0.8 have been analyzed using Monte Carlo simulations with Cao-Berne propagator. Energies, pressures, and structural quantities (pair radial correlation functions, centroid structure factors, and Steinhardt order parameters) have been computed. Also, applications of the Einstein crystal technique [L. M. Sesé, J. Chem. Phys. 126, 164508 (2007)] have been made to compute the free energies of the fcc and hcp solids. Some technical points related to the latter technique are discussed, and it is shown that these calculations produce consistent results with increasing sample sizes. The fluid-solid (fcc and hcp) equilibria have been studied, thus completing prior work by this author on the fluid-fcc equilibrium. Within the accuracy attained no significant differences between the relative stabilities of the fcc and hcp lattices have been detected. The bcc case stands apart from the other two lattices, as the simulations lead either to irregular lattices (two types) that keep some traces of bcc-memory, or to spontaneous transitions to hcp-like lattices. The latter transitions make manifestly clear the potential repercussions that the quantum hard-sphere behavior can have on solid-solid equilibria at low temperatures in real systems (e.g., helium).
Relevance of the Thorpe length scale in stably stratified turbulence
Authors: Mater Benjamin D. , Schaad Simon M. , Venayagamoorthy Subhas Karan
Published: July 2013

Direct numerical simulations of stably stratified turbulence are used to compare the Thorpe overturn length scale, LT, with other length scales of the flow that can be constructed from large-scale quantities fundamental to shear-free, stratified turbulence. Quantities considered are the turbulent kinetic energy, k, its dissipation rate, ε, and the buoyancy frequency, N. Fundamental length scales are then the Ozmidov length scale, LO, the isotropic large scale, Lkε, and a kinetic energy length scale, LkN. Behavior of all three fundamental scales, relative to LT, is shown to be a function of the buoyancy strength parameter NTL, where TL = k/ε is the turbulence time scale. When buoyancy effects are dominant (i.e., for NTL > 1), LT is shown to be linearly correlated with LkN and not with LO as is commonly assumed for oceanic flows. Agreement between LO and LT is only observed when the buoyancy and turbulence time scales are approximately equal (i.e., for the critical case when NTL ≈ 1). The relative lack of agreement between LT and LO in strongly stratified flows is likely due to anisotropy at the outer scales of the flow where the energy transfer rate differs from ε. The key finding of this work is that observable overturns in strongly stratified flows are more reflective of k than ε. In the context of oceanic observations, this implies that inference of k, rather than ε, from measurements of LT is fundamentally correct when NTL ≈ 1 and most appropriate when NTL > 1. Furthermore, we show that for NTL < 1, LT is linearly correlated with Lkε when mean shear is absent.
A construction of the Reynolds-averaged turbulence transport equations in a variable-density flow, based on the concept of mass-weighted fluctuations
Authors: Yoshizawa Akira , Matsuo Yuichi , Mizobuchi Yasuhiro
Published: July 2013

The mass-weighted Reynolds averaging in a variable-density flow leads to a system of mean-field and turbulent-flux equations whose mathematical structures are quite similar to the constant-density counterparts. Owing to this compactness, the averaging is widely used in the study of aeronautical and combusting flows subject to large density variation. In the formalism, the conventional Reynolds averages of velocity and scalar fluctuations under the mass-weighted averaging occur as important ingredients in the turbulent-flux equations such as the Reynolds-stress one. Their proper estimate is indispensable for the Reynolds-averaged closure modeling of a variable-density flow. In the present formalism, the concept of mass-weighted fluctuations is introduced, while the mean field is based on the mass-weighted averaging. As a result, the occurrence of the foregoing averages is avoided, and the transport equations for four primary turbulent fluxes are formulated in a form quite similar to one another. The proposed formalism is instrumental to clearly extracting the effects intrinsic to density variation, and the smooth transition of a Reynolds-averaged system of equations between variable- and constant-density flows is guaranteed. The system is applicable to the Reynolds-averaged closure modeling.
Topologies on quantum topoi induced by quantization
Authors: Nakayama Kunji
Published: July 2013

In the present paper, we consider effects of quantization in a topos approach of quantum theory. A quantum system is assumed to be coded in a quantum topos, by which we mean the topos of presheaves on the context category of commutative subalgebras of a von Neumann algebra of bounded operators on a Hilbert space. A classical system is modeled by a Lie algebra of classical observables. It is shown that a quantization map from the classical observables to self-adjoint operators on the Hilbert space naturally induces geometric morphisms from presheaf topoi related to the classical system to the quantum topos. By means of the geometric morphisms, we give Lawvere-Tierney topologies on the quantum topos (and their equivalent Grothendieck topologies on the context category). We show that, among them, there exists a canonical one which we call a quantization topology. We furthermore give an explicit expression of a sheafification functor associated with the quantization topology.
Hydrodynamics of air entrainment by moving contact lines
Authors: Chan T. S. , Srivastava S. , Marchand A. , Andreotti B. , Biferale L. , Toschi F. , Snoeijer J. H.
Published: July 2013

We study the dynamics of the interface between two immiscible fluids in contact with a chemically homogeneous moving solid plate. We consider the generic case of two fluids with any viscosity ratio and of a plate moving in either directions (pulled or pushed in the bath). The problem is studied by a combination of two models, namely, an extension to finite viscosity ratio of the lubrication theory and a Lattice Boltzmann method. Both methods allow to resolve, in different ways, the viscous singularity at the triple contact between the two fluids and the wall. We find a good agreement between the two models particularly for small capillary numbers. When the solid plate moves fast enough, the entrainment of one fluid into the other one can occur. The extension of the lubrication model to the case of a non-zero air viscosity, as developed here, allows us to study the dependence of the critical capillary number for air entrainment on the other parameters in the problem (contact angle and viscosity ratio).
Research on a logarithmically bent Laue crystal analyzer for X-ray monochromatic backlight imaging
Authors: Wu Yufen , Xiao Shali , Lu Jian , Liu Lifeng , Yang Qingguo , Huang Xianbin
Published: July 2013

A new logarithmically bent Laue imaging crystal analyzer (LBLICA) was proposed to obtain the monochromatic image of plasmas and exhibited a great potential for application in the Inertial Confinement Fusion experiment over a large field of view (FOV) and with a high spatial resolution. The imaging geometry of the LBLICA has been discussed. According to the Bragg condition and the equation of the logarithmic spiral, the key image parameters of the crystal analyzer, including the system magnification, the spatial resolution, and the FOV, have been analyzed theoretically. An experiment has been performed with a Cu target X-ray tube as a backlighter to backlight a mesh grid consisting of 50-μm Cu wires, and the monochromatic image of the grid has been obtained with a spatial resolution of approximately 30 μm.
Measurement of the edge plasma rotation on J-TEXT tokamak
Authors: Cheng Z. F. , Luo J. , Wang Z. J. , Zhang Z. P. , Zhang X. L. , Hou S. Y. , Cheng C. , Zhuang G.
Published: July 2013

A multi-channel high resolution spectrometer was developed for the measurement of the edge plasma rotation on J-TEXT tokamak. With the design of two opposite viewing directions, the poloidal and toroidal rotations can be measured simultaneously, and velocity accuracy is up to 1 km/s. The photon flux was enhanced by utilizing combined optical fiber. With this design, the time resolution reaches 3 ms. An assistant software “Spectra Assist” was developed for implementing the spectrometer control and data analysis automatically. A multi-channel monochromatic analyzer is designed to get the location of chosen ions simultaneously through the inversion analysis. Some preliminary experimental results about influence of plasma density, different magnetohydrodynamics behaviors, and applying of biased electrode are presented.
Pinning controllability of complex networks with community structure
Authors: Miao Qingying , Tang Yang , Kurths Jürgen , Fang Jian-an , Wong W. K.
Published: July 2013

In this paper, we study the controllability of networks with different numbers of communities and various strengths of community structure. By means of simulations, we show that the degree descending pinning scheme performs best among several considered pinning schemes under a small number of pinned nodes, while the degree ascending pinning scheme is becoming more powerful by increasing the number of pinned nodes. It is found that increasing the number of communities or reducing the strength of community structure is beneficial for the enhancement of the controllability. Moreover, it is revealed that the pinning scheme with evenly distributed pinned nodes among communities outperforms other kinds of considered pinning schemes.
Analysis of the effects of energy deposition on shock-driven turbulent mixing
Authors: Haines Brian M. , Grinstein Fernando F. , Welser-Sherrill Leslie , Fincke James R. , Doss Forrest W.
Published: July 2013

We perform simulations of laser-driven turbulence experiments with energy deposition, modeling situations where energy is deposited in a mixing layer before or after it is reshocked. Such situations are experienced in, e.g., inertial confinement fusion capsules. We show that the timing of the energy deposition has a significant impact on the development of turbulent flow and corresponding turbulent material mixing. In particular, if the energy is deposited before the shock wave begins interacting with the mixing layer, the development of turbulence and turbulent mixing are inhibited. If, however, the energy is deposited after the shock wave has interacted with a portion of the mixing layer, turbulence generation and turbulent mixing are enhanced.
Localised vibrational mode spectroscopy studies of self-interstitial clusters in neutron irradiated silicon
Authors: Londos C. A. , Antonaras G. , Chroneos A.
Published: July 2013

The evolution of self-interstitial clusters in silicon (Si), produced by fast neutron irradiation of silicon crystals followed by anneals up to 750 °C, is investigated using localised vibrational mode spectroscopy. A band at 582 cm−1 appears after irradiation and is stable up to 550 °C was attributed to small self-interstitial clusters (In, n ≤ 4), with the most probable candidate the I4 structure. Two bands at 713 and 758 cm−1 arising in the spectra upon annealing of the 582 cm−1 band and surviving up to ∼750 °C were correlated with larger interstitial clusters (In, 5 ≤ n ≤ 8), with the most probable candidate the I8 structure or/and with chainlike defects which are precursors of the {311} extended defects. The results illustrate the presence of different interstitial clusters In, at the various temperature intervals of the material, in the course of an isochronal anneal sequence. As the annealing temperature increases, they evolve from first-order structures with a small number of self-interstitials (In, n ≤ 4) for the temperatures 50 < T < 550 °C, to second order structures (In, 5 ≤ n ≤ 8) with a larger number of interstitials, for the temperatures 550 < T < 750 °C.
Photoacoustic response of suspended and hemolyzed red blood cells
Authors: Saha Ratan K. , Karmakar Subhajit , Roy Madhusudan
Published: July 2013

The effect of confinement of hemoglobin molecules on photoacoustic (PA) signal is studied experimentally. The PA amplitudes for samples with suspended red blood cells (SRBCs) and hemolyzed red blood cells (HRBCs) were found to be comparable at each hematocrit for 532 nm illumination. The difference between the corresponding amplitudes increased with increasing hematocrit for 1064 nm irradiation. For example, the PA amplitude for the SRBCs was about 260% higher than that of the HRBCs at 40% hematocrit. This observation may help to develop a PA method detecting hemolysis noninvasively.
Negative-U behavior of the Si donor in Al0.77Ga0.23N
Authors: Thang Trinh Xuan , Nilsson Daniel , Ivanov Ivan G. , Janzén Erik , Kakanakova-Georgieva Anelia , Tien Son Nguyen
Published: July 2013

Electron paramagnetic resonance (EPR) spectrum of a shallow donor is observed at low temperatures in darkness in Si-doped Al0.77Ga0.23N epitaxial layers grown on 4H-SiC substrates. It is shown from the temperature dependence of the donor concentration on the neutral donor state measured by EPR that Si is a DX (or negative-U) center but behaves as a shallow donor due to a small separation of only ∼3 meV between the neutral state Ed and the lower-lying negative state EDX. The neutral state is found to follow the effective mass theory with Ed ∼ 52–59 meV.
Laser-processed three dimensional graphitic electrodes for diamond radiation detectors
Authors: Caylar Benoît , Pomorski Michal , Bergonzo Philippe
Published: July 2013

We have used an original approach for diamond detectors where three dimensional buried graphitic electrodes are processed in the bulk of a diamond substrate via laser-induced graphitization. Prototype made of polycrystalline chemical vapor deposition diamond was fabricated using a nanosecond UV laser. Its charge collection efficiency was evaluated using α-particles emitted by a 241-Americium source. An improved charge collection efficiency was measured proving that laser micro-machining of diamond is a valid option for the future fabrication of three dimensional diamond detectors.
Tip-sensitive all-silica fiber-optic Fabry–Perot ultrasonic hydrophone for charactering high intensity focused ultrasound fields
Authors: Wang D. H. , Jia P. G. , Wang S. J. , Zhao C. L. , Zeng D. P. , Wang H. , Li F. Q.
Published: July 2013

This Letter reports on a tip-sensitive all-silica fiber-optic Fabry–Perot (TAFOFP) ultrasonic hydrophone for measuring high intensity focused ultrasound (HIFU) fields. The all-silica fiber-optic structure ensures that the TAFOFP ultrasonic hydrophone can withstand HIFU fields and the tip-sensitive configuration ensures that the TAFOFP ultrasonic hydrophone can achieve a high spatial resolution of 125 μm. The experimental results have shown that the TAFOFP ultrasonic hydrophone could stably measure the peak positive ultrasonic pressure as high as 4.34 MPa, and the measured ultrasonic pressure distributions of the HIFU field by the fabricated TAFOFP ultrasonic hydrophone agreed well with those by the piezoceramic needle hydrophone.
Nanopore density effect of polyacrylamide gel plug on electrokinetic ion enrichment in a micro-nanofluidic chip
Authors: Wang Jun-yao , Xu Zheng , Li Yong-kui , Liu Chong , Liu Jun-shan , Chen Li , Du Li-qun , Wang Li-ding
Published: July 2013

In this paper, the nanopore density effect on ion enrichment is quantitatively described with the ratio between electrophoresis flux and electroosmotic flow flux based on the Poisson-Nernst-Planck equations. A polyacrylamide gel plug is integrated into a microchannel to form a micro-nanofluidic chip. With the chip, electrokinetic ion enrichment is relatively stable and enrichment ratio of fluorescein isothiocyanate can increase to 600-fold within 120 s at the electric voltage of 300 V. Both theoretical research and experiments show that enrichment ratio can be improved through increasing nanopore density. The result will be beneficial to the design of micro-nanofluidic chips.
Large-area, well-ordered, uniform-sized bowtie nanoantenna arrays for surface enhanced Raman scattering substrate with ultra-sensitive detection
Authors: Dai Zhigao , Xiao Xiangheng , Liao Lei , Zheng Junfeng , Mei Fei , Wu Wei , Ying Jianjian , Ren Feng , Jiang Changzhong
Published: July 2013

We report the fabrication of large-area, well-ordered, uniform-sized noble metal bowtie nanoantenna arrays used as an ultra-sensitive surface-enhanced Raman scattering (SERS) substrate by a refined combination of colloid lithography and subsequent oxygen plasma processing. The tip-to-tip distance between neighboring nanotriangles is made as small as 10 nm by accurately controlling the etching time. Owing to the nanoscale property, the as-fabricated Ag bowtie nanoantenna arrays exhibit a local SERS enhancement larger than 107. The experimental results were confirmed by theoretical calculations.
Terahertz quantum cascade lasers based on quaternary AlInGaAs barriers
Authors: Ohtani K. , Beck M. , Scalari G. , Faist J.
Published: July 2013

Terahertz quantum cascade lasers incorporating lattice-matched quaternary AlInGaAs barriers grown by molecular beam epitaxy on InP substrate are reported. Four quantum well active region devices exhibited lasing at 3.8 THz with threshold current densities as low as 74 A/cm2 at 10 K. From optical characterization and a doping study of the active region, an upper state lifetime of 8 ps, as well as a long transport time across the active region of 68 ps and a ratio of free carrier loss to gain cross sections of 4.6%, is reported. A maximum operating temperature of 130 K was achieved for a device with a conduction band discontinuity of 0.14 eV.
Phase transition signature on elastic constants in Al1-xCrxNy ternary alloys thin films
Authors: Pham T. , Faurie D. , Djemia P. , Belliard L. , Le Bourhis E. , Goudeau P. , Paumier F.
Published: July 2013

According to Cr content, ternary Al1-xCrxNy films structure evolves from hexagonal to cubic phase. Despite numerous studies on their mechanical properties in relation with the deposition process, the relationship between this phase transition and elastic properties has never been deeply studied. In this paper, the transition has been evidenced by picoseconds ultrasonic and Brillouin light scattering at a chromium concentration of 40 at. % and is characterized by a strong increase of C33 and C44 effective elastic constants (respectively, +83% and +70%).
Effect of the synthetic antiferromagnetic polarizer layer rigidness on the spin transfer torque switching current density
Authors: You Chun-Yeol
Published: July 2013

We investigate the effect of the synthetic antiferromagnetic polarizer layer rigidness on the switching current density of spin transfer torque magnetic tunneling junction with micromagnetic simulations. In contrary to the general belief, surprisingly, the rigidness of the polarizer layer affects to the spin dynamics of the free layer and it causes the switching current density changes. When the rigidness of the synthetic antiferromagnetic polarizer layer is weakened by reducing the interlayer exchange coupling energy, we found that the switching current density can be reduced due to the more effective switching process.
Performance enhancement of polymer solar cells with luminescent down-shifting sensitizer
Authors: Ma Guo-Fu , Xie Hao-Jun , Cheng Pan-Pan , Li Yan-Qing , Tang Jian-Xin
Published: July 2013

Enhanced performance of polymer solar cells is reported by incorporating a solution-processed luminescent down-shifting (LDS) sensitizer, which is composed of a C545T fluorescent molecule doped tris(8-quinolinolato) aluminum (C545T:Alq3). An optimized LDS sensitizer can result in ∼15% enhancement in power conversion efficiency than the reference device with pristine Alq3. The performance enhancement is associated with the increase in photocurrent induced by LDS sensitizer, which is capable of absorbing short-wavelength solar spectrum and re-emitting long-wavelength light, which is complementary with the absorption spectrum of the active layer. This method provides a facile approach for high-performance polymer solar cell designs.
Generation of extended light-sheets for single and multi-photon fluorescence microscopy
Authors: Purnapatra Subhajit B. , Pratim Mondal Partha
Published: July 2013

We theoretically propose and computationally demonstrate the generation of extended light-sheet for fluorescence microscopy. This is made possible by the introduction of a specially designed double-window spatial filter that allows the light to pass through the periphery and center of a cylindrical lens. When illuminated with a plane wave, the proposed filter results in an extended depth-of-focus along with side-lobes which are due to other interferences in the transverse focal plane. Computational studies show a maximum extension of light-sheet by 3.38 times for single photon excitation and 3.68 times for multiphoton excitation as compared to state-of-art single plane illumination microscopy system. This technique may facilitate the study of large biological specimens (such as Zebrafish embryo and tissue) with high spatial resolution and reduced photobleaching.
Impact of proton irradiation on deep level states in n-GaN
Authors: Zhang Z. , Arehart A. R. , Cinkilic E. , Chen J. , Zhang E. X. , Fleetwood D. M. , Schrimpf R. D. , McSkimming B. , Speck J. S. , Ringel S. A.
Published: July 2013

Deep levels in 1.8 MeV proton irradiated n-type GaN were systematically characterized using deep level transient spectroscopies and deep level optical spectroscopies. The impacts of proton irradiation on the introduction and evolution of those deep states were revealed as a function of proton fluences up to 1.1 × 1013 cm−2. The proton irradiation introduced two traps with activation energies of EC - 0.13 eV and 0.16 eV, and a monotonic increase in the concentration for most of the pre-existing traps, though the increase rates were different for each trap, suggesting different physical sources and/or configurations for these states. Through lighted capacitance voltage measurements, the deep levels at EC - 1.25 eV, 2.50 eV, and 3.25 eV were identified as being the source of systematic carrier removal in proton-damaged n-GaN as a function of proton fluence.
Theoretical studies on pyrolysis mechanism of guaiacol as lignin model compound
Authors: Huang Jinbao , Li Xinsheng , Wu Dan , Tong Hong , Li Weimin
Published: July 2013

The pyrolysis processes of guaiacol as lignin model compound were theoretically investigated by using density functional theory methods at B3LYP/6-31G++(d,p) level. The bond dissociation enthalpies (BDE) of the major bonds of guaiacol were calculated. Three possible pyrolytic pathways were proposed according to related experimental results, calculation results of BDE of guaiacol and research experiences. The standard kinetic parameters in each reaction pathway were calculated. In reaction pathway (1), the initial reaction step of guaiacol pyrolysis is the homolytic cleavage of the CH3-O bond and 1,2-dihydroxybenzene is the main pyrolysis product, of which the total energy barrier of formation is 312.9 kJ/mol. In reaction pathway (2), the initial reaction step of guaiacol pyrolysis is the homolytic cleavage of the O-H bond and the main pyrolysis products are o-cresol, 2-hydroxybenzaldehyde, o-quinonemethide, of which the total energy barrier of formation is 474.1 kJ/mol. In reaction pathway (3), addition of H to the carbon atom of benzene ring can effectively lower the activation energy of demethoxy reaction of guaiacol. Based on kinetic analysis results, we can infer that the main pyrolysis products are 1,2-dihydroxybenzene, methane, phenol, o-cresol, 2-hydroxybenzaldehyde, and coke.
Passively mode-locking induced by gold nanorods in erbium-doped fiber lasers
Authors: Kang Zhe , Xu Yang , Zhang Lei , Jia Zhixu , Liu Lai , Zhao Dan , Feng Yan , Qin Guanshi , Qin Weiping
Published: July 2013

We demonstrated a passively mode-locked erbium-doped fiber laser by using gold nanorods as a saturable absorber. The gold nanorods (GNRs) were mixed with sodium carboxymethylcellulose (NaCMC) to form GNRs-NaCMC films. By inserting one of the GNRs-NaCMC films into an EDFL cavity pumped by a 980 nm laser diode, stable passively mode-locking was achieved with a threshold pump power of ∼54 mW, and 12 ps pulses at 1561 nm with a repetition rate of 34.7 MHz and a maximum average power of ∼2.05 mW were obtained for a pump power of ∼62 mW.
Agricultural impact on the pelagic ecosystem of the small temporarily open/closed Seteni Estuary, South Africa
Authors: Carrasco N. K. , Perissinotto R. , Whitehead A.
Published: July 2013

The encroachment of agriculture and human population is placing increasing levels of stress on estuarine ecosystems worldwide. The catchment of the Seteni Estuary, a small temporarily open/closed estuary in South Africa, has been under extensive sugar cultivation for over 60 years. The present study reports on the impact of agricultural practices on the structure and dynamics of its pelagic communities over a 1-year period, from April 2008 to March 2009. The physico-chemical characteristics of the system were strongly linked to seasonality, with the system exhibiting a distinct open- and closed-mouth phase in response to rainfall. Concentrations of dissolved inorganic nitrogen (DIN) were exceptionally high in comparison to concentrations of dissolved inorganic phosphorus (DIP), resulting in high DIN : DIP ratios. Despite this, microalgal biomass remained relatively low, exhibiting maximum values of 91.7 mg chl a m–2 and 18.0 mg chl a m–3 for microphytobenthos and phytoplankton, respectively. Zooplankton abundance and biomass were significantly higher during the dry phase, with Pseudodiaptomus hessei dominating the zooplankton community both in terms of abundance and biomass throughout the study period. The ichthyofaunal community was dominated by Ambassis ambassis and Myxus capensis in terms of abundance and biomass, respectively. Results suggest that the system remains functional, but there is potential for deterioration, should the catchment become more nutrient-rich through poor management or land-use changes.
A novel subclass of bovine β-defensins links reproduction and immunology
Authors: Narciandi F. , Lloyd A. , Meade K. G. , O'Farrelly C.
Published: July 2013

β-defensins are effector molecules of the innate immune system, found in many diverse species. Their presence in invertebrates as well as vertebrates suggests highly conserved functional roles. Most β-defensins are believed to act as antimicrobial agents at epithelial surfaces, although additional functions have also been described, including immune regulatory activity, wound repair and a role in coat-colour determination. High expression of β-defensins have been found in testis and epididymidal epithelium as well as in the seminal fluid of humans, macaque, rat, mouse and cow. Human and macaque β-defensins have recently been shown to affect sperm motility while a mutation in β-defensin 126 is associated with reduced fertility in men. Genetic variation in bovine defensin genes may explain the increased incidence of low fertility in cattle. Here, we present a summary of the known functions of β-defensins as well as their emerging role in reproduction and their potential to improve fertility in cattle.
Impacts of traditional livestock corrals on woody plant communities in an East African savanna
Authors: Veblen Kari E.
Published: July 2013

In African savannas, humans and their livestock leave long-term legacies on the landscape in the form of abandoned livestock bomas (corrals). Once abandoned, bomas develop into nutrient-rich herbivore hotspots characterised by distinctive plant communities. Impacts of bomas, however, extend beyond the boundaries of the boma site itself. This is especially true for woody species which are intensively harvested for boma fencing material and fuel wood. Following boma abandonment, it is not clear how quickly, or to what extent, woody plant communities may change and develop over time. A chronosequence approach was used to investigate the effects of traditional livestock bomas on woody plant communities over time in an Acacia drepanolobium Sjost. savanna in central Kenya. Densities of woody species associated with boma sites that had been abandoned <4, 7–42, and >42 years before were measured. Reductions in densities of the dominant tree, A. drepanolobium, were still detectable after >42 years, especially in the highest impact zones at boma edges (up to 60 m from the boma). Despite these overall reductions, the edge zones of old boma sites had unusually high densities of very large A. drepanolobium trees. Woody species richness increased at edges of newly abandoned bomas, as did densities of the uncommon shrub Lycium europaeum L., and these changes persisted for several decades. These patterns likely result from interactions among species within the woody plant community, as well as interactions with herbivores and edaphic factors.
Handling power-asymmetry in interactions with infants
Authors: Demuth Carolin
Published: July 2013

Interaction between adults and infants by nature constitutes a strong powerasymmetry relationship. Based on the assumption that communicative practices with infants are inseparably intertwined with broader cultural ideologies of good child care, this paper will contrast how parents in two distinct socio-cultural communities deal with power asymmetry in interactions with 3-months old infants. The study consists of a microanalysis of videotaped free play mother-infant interactions from 20 middle class families in Muenster, Germany and 20 traditional farming Nso families in Kikaikelaki, Cameroon. Analysis followed a discursive psychology approach. The focus of analysis is on how mothers handle and negotiate power-distance in these interactions and what discursive strategies they draw on. Mothers in both groups used various forms of directives and control strategies. The Muenster mothers, however, mainly used mitigated directives that can be seen as strategies to reduce the competence gap between mother and child, while the Nso mothers mainly used upgraded directives to stress the hierarchical discrepancy between mother and child. The different strategies are discussed in light of the prevailing broader cultural ideologies and the normative orientations that they reflect. Finally, the findings are discussed with regard to possible developmental consequences of these distinct cultural practices for the child. Keywords: power-asymmetry; mother-infant interaction; discursive psychology; culture; Nso farmers; Muenster middle class families
Injury-Related Consequences of Alcohol Misuse among Injured Patients who Received Screening and Brief Intervention for Alcohol: A Latent Class Analysis
Authors: Cochran Gerald , Field Craig , Caetano Raul
Published: July 2013

Background

Screening and brief alcohol intervention has demonstrated efficacy in improving drinking and other risk behaviors for some patient populations. However, it is not clear that brief interventions are helpful to all injured patients who drink at risk levels. This paper identifies latent classes of intervention recipients based on injury-related consequences and risks of alcohol misuse and then determines which profiles experienced the greatest improvements in drinking.

Methods

A secondary analysis was conducted using data from injured patients ( N = 737) who reported heavy drinking and received a brief alcohol intervention in a Level I trauma center. Latent class analysis was used to determine patient profiles, and 7 indicators commonly associated with alcohol-related injury from the Short Inventory of Problems+6 were used to determine the latent class measurement model. Covariates were regressed onto the model to assess factors related to class membership, and drinking outcomes were analyzed to examine improvements in drinking.

Results

Five classes emerged from the data. The classes that reported the greatest improvements in drinking following discharge were those characterized by multiple alcohol-related risks and those characterized by a history of alcohol-related accidents and injuries. Attributing the current injury to drinking was a significant predictor of class membership among those classes that reported higher levels of improvement.

Conclusions

This study provides tentative evidence that subclasses exist among heavy drinking injured patients who received a brief intervention in a Level I trauma center, and some subclasses experience greater drinking improvements than others. Further research is required to substantiate the findings of this secondary analysis.
A notational analysis of shot characteristics in top‐level table tennis players
Authors: Malagoli Lanzoni Ivan , Di Michele Rocco , Merni Franco
Published: July 2013

This study aimed to analyse selected shot characteristics in top‐level table tennis matches, with a special focus on comparing the playing style of Asian and European players. Ten men's matches played by 20 top‐ranked players (14 Asians and 6 Europeans) were analysed. The indicators examined were the area of ball bouncing for serves (n =918), and the stroke type, footwork type and shot outcome for other shots (n=3692). The interrelationships between variables were analysed using chi‐squared tests, log‐linear modelling and multiple correspondence analysis. A strong association was found between strokes and footwork types, with most stroke types executed each after specific footwork types. Furthermore, a clear tendency to have a positive, negative or neutral outcome was observed for each stroke type. When compared to Europeans, Asians used more frequently the most aggressive strokes and footwork types, confirming anecdotal claims on their particularly offensive playing style. Asians showed also a better serving effectiveness, often sending the ball in those areas of the table from which a counterattack is difficult to make. In summary, this study gives a systematic description of highly relevant technical and tactical characteristics in top‐level table tennis, thus providing valuable information for coaches and performance analysts.
Membrane remodeling by the PX-BAR protein SNX18 promotes autophagosome formation
Authors: Knævelsrud Helene , Søreng Kristiane , Raiborg Camilla , Håberg Karin , Rasmuson Fredrik , Brech Andreas , Liestøl Knut , Rusten Tor Erik , Stenmark Harald , Neufeld Thomas P. , Carlsson Sven R. , Simonsen Anne
Published: July 2013

The membrane remodeling events required for autophagosome biogenesis are still poorly understood. Because PX domain proteins mediate membrane remodeling and trafficking, we conducted an imaging-based siRNA screen for autophagosome formation targeting human PX proteins. The PX-BAR protein SNX18 was identified as a positive regulator of autophagosome formation, and its Drosophila melanogaster homologue SH3PX1 was found to be required for efficient autophagosome formation in the larval fat body. We show that SNX18 is required for recruitment of Atg16L1-positive recycling endosomes to a perinuclear area and for delivery of Atg16L1- and LC3-positive membranes to autophagosome precursors. We identify a direct interaction of SNX18 with LC3 and show that the pro-autophagic activity of SNX18 depends on its membrane binding and tubulation capacity. We also show that the function of SNX18 in membrane tubulation and autophagy is negatively regulated by phosphorylation of S233. We conclude that SNX18 promotes autophagosome formation by virtue of its ability to remodel membranes and provide membrane to forming autophagosomes.
Systematic characterization of the conformation and dynamics of budding yeast chromosome XII
Authors: Albert Benjamin , Mathon Julien , Shukla Ashutosh , Saad Hicham , Normand Christophe , Léger-Silvestre Isabelle , Villa David , Kamgoue Alain , Mozziconacci Julien , Wong Hua , Zimmer Christophe , Bhargava Purnima , Bancaud Aurélien , Gadal Olivier
Published: July 2013

Chromosomes architecture is viewed as a key component of gene regulation, but principles of chromosomal folding remain elusive. Here we used high-throughput live cell microscopy to characterize the conformation and dynamics of the longest chromosome of Saccharomyces cerevisiae (XII). Chromosome XII carries the ribosomal DNA (rDNA) that defines the nucleolus, a major hallmark of nuclear organization. We determined intranuclear positions of 15 loci distributed every ∼100 kb along the chromosome, and investigated their motion over broad time scales (0.2–400 s). Loci positions and motions, except for the rDNA, were consistent with a computational model of chromosomes based on tethered polymers and with the Rouse model from polymer physics, respectively. Furthermore, rapamycin-dependent transcriptional reprogramming of the genome only marginally affected the chromosome XII internal large-scale organization. Our comprehensive investigation of chromosome XII is thus in agreement with recent studies and models in which long-range architecture is largely determined by the physical principles of tethered polymers and volume exclusion.