bluuebunny/crossref_metadata_2025 huggingface dataset:
An isocenter detection and verification device for use in proton therapy
Authors: Fuse H. , Sakae T. , Terunuma T. , Sato M. , Aoki S.
Published: December 2012

We developed a new device for isocenter detection and verification for use in proton therapy. This device can be used to confirm the isocenters of a room laser, a digital radiography system, and a rotational gantry. Agreement between the isocenters of a room laser and a digital radiography system was examined visually. We used the star-shots method for detecting and verifying the rotational gantry isocenter. The gafchromic film could be irradiated with this method using a 2 mm slitted 200 MeV proton beam. The isocenters of a room laser and digital radiography system were in good agreement. The size distribution of the isocenter by the star-shots method was <2 mm, which is the value recommended by the American Association of Physicists in Medicine Task Group 142. This new device can be used to evaluate comprehensive isocenter detection and verification for related equipment. Subsequent checking using this new device will decrease the uncertainty in measuring an isocenter. When using this device, the working time was significantly reduced to about 30 min, including preparation. These measurements should be useful for high accuracy daily treatments.
A quasi-static model of drop impact
Authors: Moláček Jan , Bush John W. M.
Published: December 2012

We develop a conceptually simple theoretical model of non-wetting drop impact on a rigid surface at small Weber numbers. Flat and curved impactor surfaces are considered, and the influence of surface curvature is elucidated. Particular attention is given to characterizing the contact time of the impact and the coefficient of restitution, the goal being to provide a reasonable estimate for these two parameters with the simplest model possible. Approximating the shape of the drop during impact as quasi-static allows us to derive the governing differential equation for the droplet motion from a Lagrangian. Predictions of the resulting model are shown to compare favorably with previously reported experimental results.
Three-dimensional single particle tracking in dense dust clouds by stereoscopy of fluorescent particles
Authors: Himpel Michael , Killer Carsten , Buttenschön Birger , Melzer André
Published: December 2012

In dense dust clouds of a dusty plasma single particle trajectories are impossible to follow due to occlusion of particles and ambiguities in particle correspondences. By stereoscopic imaging of fluorescent tracer particles, we were able to reconstruct 3D single particle trajectories within dense dust clouds. Several measurements are shown that justify to regard the tracer particles as suitable representatives for the whole dust system. A first analysis of dust density waves in dense clouds already shows that these waves exhibit three-dimensional dynamics at larger wave amplitudes that cannot be resolved by 2D imaging techniques: a broad velocity distribution perpendicular to the oscillation plane due to dust-dust collisions is seen, while the velocity distribution in the oscillation direction is bimodal and shifted due to the bulk wave propagation.
Periodic orbits of the spatial anisotropic Manev problem
Authors: Llibre Jaume , Makhlouf Ammar
Published: December 2012

We study the periodic orbits of the spatial anisotropic Manev problem, which depend on three parameters.
Support effects on the dissociation of hydrogen over gold clusters on ZnO(101) surface: Theoretical insights
Authors: Li Zhe , Li Yongxiu , Li Jinlin
Published: December 2012

We perform density functional studies of the support effects on the gold-catalyzed dissociation of H2 using the model clusters (Au10 and Au13) on ZnO(101) surface and find that H2 prefers to adsorb on the bottom layer of Au clusters on the ZnO surface. The interaction energies of H2 are exponentially correlated with the H–H and H–Au bond parameters. The dissociation of H2 easily occurs on the bottom layer with the energy barriers no more than 0.44 eV. The support effects on the dissociation barriers are greatly dependent on the H–H bond distance in the transition state (TS), i.e., the early TSs with small barriers have larger support effects than the late TSs with large barriers. We find that the charge transfer from the gold clusters to the oxide support creates the localized charging states of the interface gold with the high feasibility for H2 activation and dissociation.
The generation of zonal jets by large-scale mixing
Authors: Scott R. K. , Tissier A.-S.
Published: December 2012

The development of zonal flows on a midlatitude β-plane subject to a time-varying topographic forcing is investigated in a series of numerical integrations in which the forcing is concentrated at large scales, and in which the usual two-dimensional inverse energy cascade is absent. In contrast to the case of small-scale forcing, where mixing of potential vorticity occurs largely through the action of small-scale eddies, mixing of potential vorticity in this case occurs predominantly in latitudinally localized Rossby wave critical layer regions, whose width grows continuously in time due to the entrainment of background fluid. The potential vorticity is found to organize into a piecewise constant staircase-like profile, monotonic in latitude, provided the ratio \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}/L_f\gtrsim 1$\end{document}LRh/Lf≳1, where \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}$\end{document}LRh is the usual Rhines scale and Lf is the scale of the forcing; this may be regarded as supplemental to the condition \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}/L_{\varepsilon }\gtrsim 6$\end{document}LRh/Lɛ≳6, where Lɛ = (ɛ/β3)1/5 and ɛ is the rate of energy input, obtained recently [R. K. Scott and D. G. Dritschel, “The structure of zonal jets in geostrophic turbulence,” J. Fluid Mech. 711, 576–598 (2012)10.1017/jfm.2012.410] for the case of small-scale forcing. The numerical results further suggest that the nature of the potential vorticity mixing is controlled by the ratio Lɛ/Lf, and occurs predominantly in critical layers when Lɛ/Lf ≲ 1/6. A combined condition for staircase formation may therefore be expressed as \documentclass[12pt]{minimal}\begin{document}$L_\text{Rh}/L_{\varepsilon }\gtrsim \max \lbrace 6,L_f/L_{\varepsilon }\rbrace$\end{document}LRh/Lɛ≳max{6,Lf/Lɛ}. Finally, in a separate set of experiments it is shown that when forcing is represented by an additive source term in the evolution equation, as is common practice in numerical investigations of two-dimensional turbulence, the effect of non-conservation of potential vorticity may obscure the development of the staircase profile in the critical layer mixing dominated regime.
Experimental investigation of relaminarizing and transitional channel flows
Authors: Seki Daisuke , Matsubara Masaharu
Published: December 2012

A hot-wire measurement was conducted in a planar channel flow that originated from a strongly disturbed flow in an entrance channel followed by an expansion channel used to reduce the Reynolds number (Re). From ceasing decrease of the streamwise velocity fluctuation energy and the linear extrapolation of the intermittency factor, the lower marginal Re, which is defined as the minimum Re for partial existence of sustainable turbulence, is estimated around 1400 based on the channel width and the bulk velocity. The upper marginal Re at which the intermittency factor reaches one is about 2600. The flow fields passing a turbulent patch were reconstructed with conditional sampling of the streamwise velocity data based on the time of laminar-turbulence interfaces and the reconstructed flow fields indicate a large-scale flow structure across laminar and turbulent parts. This large structure makes it possible for some regions to be at higher Re than the average, so that turbulence can partly survive. The moderate-scale disturbances larger than the turbulent one appear in the non-turbulent parts of the transitional flow, and in these cases the non-turbulent velocity profile is almost identical to the turbulent one. The large-scale fluctuation is observed even over Re = 2600. This leads to the conclusion that a turbulent channel flow close to the upper marginal Re becomes inhomogeneous.
Writing charge into the n-type LaAlO3/SrTiO3 interface: A theoretical study of the H2O kinetics on the top AlO2 surface
Authors: Li Feifei , Liang Meng , Du Wenli , Wang Mei , Feng Yexin , Hu Zhenpeng , Zhang Lixin , Wang E. G.
Published: December 2012

Ab initio calculations reveal that H2O binds strongly with the AlO2-terminated LaAlO3(100) surface and stabilizes it. The H2O dissociates into OH and H. An ionic liquid is formed at certain temperature due to the fast diffusion of the H. The OH can then be selectively removed by a Coulomb force, resulting in the charge transfer to the interface. The desorption and diffusion of the remained H atoms are the key factors to the decay of the interface conductivity. While the desorption depends on the thickness of the LaAlO3 film, the diffusion is controlled by the coverage of H2O in a vacuum environment.
Reversible superconductivity in electrochromic indium-tin oxide films
Authors: Aliev Ali E. , Xiong Ka , Cho Kyeongjae , Salamon M. B.
Published: December 2012

Transparent conductive indium tin oxide (ITO) thin films, electrochemically intercalated with sodium or other cations, show tunable superconducting transitions with a maximum Tc at 5 K. The transition temperature and the density of states, D(EF) (extracted from the measured Pauli susceptibility χp) exhibit the same dome shaped behavior as a function of electron density. Optimally intercalated samples have an upper critical field ≈ 4 T and Δ/kBTc ≈ 2.0. Accompanying the development of superconductivity, the films show a reversible electrochromic change from transparent to colored and are partially transparent (orange) at the peak of the superconducting dome. This reversible intercalation of alkali and alkali earth ions into thin ITO films opens diverse opportunities for tunable, optically transparent superconductors.
Radiation tolerance characterization of dual band InAs/GaSb type-II strain-layer superlattice pBp detectors using 63 MeV protons
Authors: Cowan V. M. , Morath C. P. , Hubbs J. E. , Myers S. , Plis E. , Krishna S.
Published: December 2012

The radiation tolerance characterization of dual band InAs/GaSb type-II strain-layer superlattice pBp detectors of varying size using 63 MeV proton irradiation is presented. The detectors' mid-wave infrared performance degraded with increasing proton fluence ΦP up to 3.75 × 1012 cm−2 or, equivalently, a total ionizing dose = 500 kRad (Si). At this ΦP, an ∼31% drop in quantum efficiency η, ∼2 order increase in dark current density JD, and consequently, >1 order drop in calculated detectivity D* were observed. Proton damage factors were determined for η and D*. Arrhenius-analysis of temperature-dependent JD measurements reflected significant changes in the activation energies following irradiation.
Electrical modulation of the optical properties of mid-infrared metamaterials
Authors: Larsen K. , Austin D. , Sandall I. C. , Davies D. G. , Revin D. G. , Cockburn J. W. , Adawi A. M. , Airey R. J. , Fry P. W. , Hopkinson M. , Wilson L. R.
Published: December 2012

We present a hybrid, mid-infrared metamaterial device, consisting of a near-surface semiconductor quantum well beneath a gold split ring resonator array. Electrical control of the free carrier concentration in the near-surface quantum well allows variation of the refractive index within the fringing field of the split ring resonator array. We observe a 10% transmission change at the fundamental resonance of the split ring resonators, in very good agreement with simulations. For optimised structures, we predict a 10% wavelength shift of the fundamental resonance, with important implications for optical components such as switches and spatial light modulators.
Local photocurrent generation in thin films of the topological insulator Bi2Se3
Authors: Kastl C. , Guan T. , He X. Y. , Wu K. H. , Li Y. Q. , Holleitner A. W.
Published: December 2012

We report on the optoelectronic properties of thin films of Bi2Se3 grown by molecular beam epitaxy. The films are patterned into circuits with typical extensions of tens of microns. In spatially resolved experiments, we observe submicron photocurrent patterns with positive and negative amplitudes. The patterns are independent of the applied bias voltage, but they depend on the width of the circuits. We interpret the patterns to originate from a local photocurrent generation due to potential fluctuations.
Carriers capturing of V-defect and its effect on leakage current and electroluminescence in InGaN-based light-emitting diodes
Authors: Le L. C. , Zhao D. G. , Jiang D. S. , Li L. , Wu L. L. , Chen P. , Liu Z. S. , Li Z. C. , Fan Y. M. , Zhu J. J. , Wang H. , Zhang S. M. , Yang H.
Published: December 2012

The effect of quantum well (QW) number on performances of InGaN/GaN multiple-quantum-well light-emitting diodes has been investigated. It is observed that V-defects, originated from various InGaN well layers intercepted by threading dislocations (TDs), increase in density and averaged size with more periods of QWs, resulting in larger reverse-bias leakage current and lower emission efficiency of light-emitting diodes. Conductive atomic force microscopy measurements demonstrate that V-defects may preferentially capture carriers, subsequently enhance local current and nonradiative recombinations at associated TD lines, which suggest that TD lines with V-defects at vertex have larger influence on emission efficiency than those without V-defects.
Experimental realization of bending waveguide using anisotropic zero-index materials
Authors: Feng Ma Hui , Hui Shi Jin , Xiang Jiang Wei , Jun Cui Tie
Published: December 2012

We experimentally demonstrate that the guiding waves can be perfectly bended and transmitted by using anisotropic zero-index materials (AZIMs). In our experiment, the split-ring resonators are used to realize AZIMs, whose permeability component along the wave propagating direction is designed as zero. Meanwhile, metal patches are designed to realize the artificial magnetic conductors as the boundaries of waveguide. The electric-field distributions are measured by two-dimensional near-field scanning apparatus in the microwave frequency, which show good bending performance as expected by simulations.
Polarization and strain response in Bi0.5K0.5TiO3-BiFeO3 ceramics
Authors: Morozov Maxim I. , Einarsrud Mari-Ann , Grande Tor
Published: December 2012

Highly dense and phase-pure ferroelectric ceramics in the (1-x)Bi0.5K0.5TiO3–xBiFeO3 system have been prepared and examined in a wide range of composition (0.1 ≤ x ≤ 0.9). The dielectric and electromechanical properties have been shown to reach a maximum value at x ≈ 0.25 demonstrating a high strain performance (250–370 pm/V in the temperature range 25–175 °C). Stability of the strain response with respect to temperature, as well as frequency and amplitude of the driving electric field is reported and discussed.
Energy transfer between few-cycle laser filaments in air
Authors: Gong Cheng , Zheng Yinghui , Zhong Yue , Zeng Zhinan , Li Chuang , Ge Xiaochun , Li Ruxin , Xu Zhizhan
Published: December 2012

We report on the energy exchange between two filaments generated by few-cycle mid-infrared laser in air. The direction of energy transfer vs the relative time delay is demonstrated distinctly as oscillations with a period of optical cycle. In addition, benefitting from the broadband spectrum of few-cycle laser pulses, we confirm an unreported fine spectral structure of energy transfer when the relative time delay is changed. The simulation results obtained by using a generalized two-beam coupling model agree well with the experimental results. A simple analytical expression has been deduced to explain the fine structure of energy transfer.
Computational fluid dynamics analysis of a trapezoidal cavity absorber used for the linear Fresnel reflector solar concentrator system
Authors: Manikumar R. , Valan Arasu A. , Jayaraj S.
Published: December 2012

Combined natural convection and surface radiation heat transfer from the surface of a trapezoidal cavity absorber of linear Fresnel reflector solar concentrator is analyzed computationally. Two dimensional, Boussinesq, steady state, laminar heat transfer model is developed and analyzed by using the ansys workbench with fluent. Two different cavity models are considered in the present analysis. Former is with absorber plate above which tubes are located and latter is without absorber plate (only absorber tubes) at the top surface of the trapezoidal cavity absorber. The analysis is carried out with the surface painted black and electroplated with nickel black selective surface coating. The validation of the present models is compared with the analytical solution obtained from matlab simulation program and also with other closed cavity models from literature. The trend in variation of estimated heat loss coefficients for the two models is similar to that of the analytical model. The obtained results are discussed in detail.
Sub-microsecond pulsed atmospheric glow discharges with and without dielectric barrier
Authors: Song Shutong , Guo Ying , Choe Wonho , Zhang Jie , Zhang Jing , Shi J. J.
Published: December 2012

The discharge characteristics and mechanism of glow discharges in atmospheric pressure helium excited by repetitive voltage pulses with and without dielectric barriers are numerically studied using a one-dimensional self-consistent fluid model. The waveforms of discharge current density show that one discharge event occurs during the voltage pulse with bare electrodes and two distinct discharge events happen at the rising and falling phases of voltage pulse with dielectric barrier electrodes, respectively. The spatial profiles of electron and electric field at the time instant of discharge current peak reveal that the electrons are trapped in the plasma bulk with bare electrodes, while the electrons are accumulated in the region between the sheath and plasma bulk with dielectric barrier electrodes. Furthermore, the spatio-temporal evolution of electron density and mean electron energy clearly demonstrate the dynamics of discharge ignition, especially the temporal evolution of sheath above the instantaneous cathode.
Preferential incorporation of substitutional nitrogen near the atomic step edges in diluted nitride alloys
Authors: Cornet C. , Nguyen Thanh T. , Quinci T. , Almosni S. , Rohel T. , Kuyyalil J. , Rambaud A. , Létoublon A. , Bertru N. , Durand O. , Le Corre A.
Published: December 2012

We have investigated the influence of the surface roughness on nitrogen incorporation during the molecular beam epitaxy of diluted nitrides, independently of the other growth parameters. GaPN/GaP layers grown simultaneously on surfaces displaying different roughnesses reveal a large difference in nitrogen incorporation despite the same growth temperature and growth rate. The same difference is found on quasi-lattice-matched GaAsPN demonstrating that the phenomenon is not related to any strain-induced mechanisms. The tendency is clearly confirmed when varying the growth conditions. As a direct consequence, the incorporation of substitutional nitrogen near the atomic step edges is found to be 6.7 times more probable than the in-plane nitrogen incorporation. The formation of N-Ni clusters and their stability on the surface is discussed.
Temperature insensitive negative Poisson's ratios in isotropic alloys near a morphotropic phase boundary
Authors: Li Dong , Jaglinski Tim , Stone Donald S. , Lakes Roderic S.
Published: December 2012

Poisson's ratio, shear modulus, and damping of polycrystalline indium-tin (In-Sn) alloys in the vicinity of the morphotropic gamma(γ)-gamma + beta(β) phase boundary were measured with resonant ultrasound spectroscopy. Negative Poisson's ratios were observed from 24 °C to 67 °C for alloys near the phase boundary. Properties were unaffected by annealing at 100 °C for 2 days. This isotropic fully dense negative Poisson's ratio material is temperature insensitive, in contrast to other materials that undergo phase transformation.
ZnO/ZnSxSe1−x/ZnSe double-shelled coaxial heterostructure: Enhanced photoelectrochemical performance and its optical properties study
Authors: Wang Zhenxing , Yin Hong , Jiang Chao , Safdar Muhammad , He Jun
Published: December 2012

Coaxial core/shell nanostructures with type II band alignment have attracted considerable attention due to their advantages in significant enhancement of visible light absorption, effective charge separation, and improved photoelectrochemical performance. In our study, ZnO/ZnSxSe1−x/ZnSe core/shell/shell nanowires have been synthesized via an effective chemical vapor deposition method. The photocurrent is significantly enhanced step-by-step from pristine ZnO, ZnO/ZnSxSe1−x core/shell, to ZnO/ZnSxSe1−x/ZnSe double-shelled nanowire photoelectrodes. The optical properties of this double-shelled nanowires are systematically studied by photoluminescence and time resolved photoluminescence. Our findings not only open an avenue for synthesis sophisticated core/shell nanowires but also pave a way towards improving photoelectrochemical properties in nanostructures.
Quantum yield of luminescence of Ag nanoclusters dispersed within transparent bulk glass vs. glass composition and temperature
Authors: Kuznetsov A. S. , Velázquez J. J. , Tikhomirov V. K. , Mendez-Ramos J. , Moshchalkov V. V.
Published: December 2012

The intensity, lifetime, and quantum yield of luminescence of Ag nanoclusters dispersed within transparent oxyfluoride glass host are shown to vary over an order of magnitude with varying glass composition and temperature. In particular, the yield may vary with glass composition from 2% to 30% at room temperature and up to 50% with decreasing temperature to 25 K, when excited at some wavelengths in ultraviolet. These variations are suggested to be governed by the change in the F-interstitials/Frenkel defects concentration, and temperature dependence of spin flip and F-interstitials assisted non-radiative decay of the photoexcited electrons on Ag nanoclusters.
Observations of pressure gradient driven m = 1 internal kink mode in EAST tokamak
Authors: Xu Liqing , Hu Liqun , Chen Kaiyun , Li Erzhong , Wang Fudi , Xu Ming , Duan Yanmin , Shi Tonghui , Zhang Jizong , Zhou Ruijie , Chen Yebin
Published: December 2012

Pressure gradient driven m = 1 internal kink mode destabilization that follows an L-H transition is observed in the operational region of the EAST tokamak, which manifests in periodic oscillations in soft x-ray (SXR) and Mirnov coil signals. Using tomography with the high resolution soft x-ray detection array, we find that the rotation direction of the 1/1 kink mode is in the ion diamagnetic drift direction in poloidal cross-section. A large displacement of the hot core is attributable to the shift of the 1/1 internal kink mode. In contrast to stationary oscillations with fixed frequency, various frequency chirping behavior is observed with this 1/1 kink mode. Furthermore, we also occasionally observe that a 2/1 neoclassical tearing mode (NTM) is triggered by a 1/1 internal kink mode via mode coupling in a high-performance plasma. The spatial structure of a 2/2 mode, which is the harmonic mode of the 1/1 kink mode, is also presented in this paper. Large amounts of medium-Z impurities accumulate in the central plasma region where the 1/1 kink mode instability bursts. Finally, we also find that the frequency beating associated with a 1/1 kink mode is a consequence of plasma rotation. Based on all of these observations, we propose that the plasma pressure gradient, the driving force in kink modes, is plausibly the product of an intense concentration of impurities, which are related to plasma rotation.
A doping-free approach to carbon nanotube electronics and optoelectronics
Authors: Peng Lian-Mao , Zhang Zhiyong , Wang Sheng , Liang Xuelei
Published: December 2012

The electronic properties of conventional semiconductor are usually controlled by doping, which introduces carriers into the semiconductor but also distortion and scattering centers to the otherwise perfect lattice, leading to increased scattering and power consumption that becomes the limiting factors for the ultimate performance of the next generation electronic devices. Among new materials that have been considered as potential replacing channel materials for silicon, carbon nanotubes (CNTs) have been extensively studied and shown to have all the remarkable electronic properties that an ideal electronic material should have, but controlled doping in CNTs has been proved to be challenging. In this article we will review a doping-free approach for constructing nanoelectronic and optoelectronic devices and integrated circuits. This technique relies on a unique property of CNTs, i.e. high quality ohmic contacts can be made to both the conduction band and valence band of a semiconducting CNT. High performance nanoelectronic and optoelectronic devices have been fabricated using CNTs with this method and performance approach to that of quantum limit. In principle high performance electronic devices and optoelectronic devices can be integrated on the same carbon nanotube with the same footing, and this opens new possibilities for electronics beyond the Moore law in the future.
Magnetically tuned varistor-transistor hybrid device
Authors: Pandey R. K. , Stapleton W. A. , Padmini P. , Dou J. , Schad R.
Published: December 2012

The paper deals with the effect of magnetic fields on the I-V characteristics of an IHC45 varistor. It is found that: (a) the nonlinear I-V characteristics of the varistor can be tuned by a magnetic field resulting in enhanced device performance; and (b) the contributions of a magnetic field on the output signal show all the characteristics of a typical transistor. The potential applications of these devices could be magnetically controlled voltage amplifiers, magnetically controlled current amplifiers, sensors, memory elements, microphone pickup with integrated pre-amplifier using a single transistor, and high temperature electronics.
Behaviour and survivorship of a dasyurid predator (Antechinus flavipes) in response to encounters with the toxic and invasive cane toad (Rhinella marina)
Authors: Kämper Wiebke , Webb Jonathan K. , Crowther Mathew S. , Greenlees Matthew J. , Shine Richard
Published: December 2012

Australia’s biogeographical isolation has rendered many endemic species vulnerable to invaders. The recent spread of the cane toad (Rhinella marina) has caused serious population declines for some predatory reptile and mammal species. To determine a priori whether or not cane toad poisoning endangers native species, we can test the fates of predators in laboratory trials. We investigated whether an Australian marsupial whose range is increasingly being occupied by cane toads (the yellow-footed antechinus, Antechinus flavipes) is at risk of toad poisoning by testing (1) whether yellow-footed antechinuses approach or attack cane toads and, if so, whether they die as a result; and (2) if they survive, whether they then learn to avoid toads in subsequent encounters. We also investigated the effects of sympatry with toads on the feeding response. In all, 58% of antechinuses from eastern New South Wales approached or attacked a toad (over 4 or 5 opportunities to do so, on successive nights), and none showed ill effects after doing so. Antechinuses that attacked (killed or ingested) toads rapidly learnt to avoid them. Antechinuses from toad-exposed populations ingested more toad flesh, but otherwise reacted in the same ways as did conspecifics from toad-free areas. Hence, the yellow-footed antechinus is unlikely to face population declines via toad poisoning.
The effect of exercise intensity on coincidence anticipation performance at different stimulus speeds
Authors: Duncan Michael , Smith Mike , Lyons Mark
Published: December 2012

The aim of this study was to examine the effect of exercise intensity on coincidence anticipation timing [CAT] performance at different stimulus speeds. Fourteen young adults (11 males and 3 females) volunteered to participate in the study following ethical approval. After familiarisation, coincidence anticipation was measured using the Bassin Anticipation Timer under three conditions: rest, moderate‐intensity and high‐intensity exercise with stimulus speeds of 3, 5 and 8 mph, set using an incremental running protocol until the participants reached a steady state of 70% and 90% of heart rate reserve (HRR), respectively. Results indicated a significant exercise intensity×stimulus speed interaction (p=0.0001) for absolute error (AE). There were no significant differences in AE across exercise intensities at a stimulus speed of 3 mph (p>0.05). AE was poorer during high‐intensity exercise (90% HRR) compared to rest (p=0.022), and moderate‐intensity (70% HRR) exercise (all, p=0.004 or better) at 5 and 8 mph. Variable error (VE) was similar across exercise intensities at stimulus speeds of both 3 and 5 mph (p>0.05). At a stimulus speed of 8 mph, VE was significantly poorer during high‐intensity exercise compared to rest (p=0.006) and moderate‐intensity exercise (p=0.008). There were no significant differences for constant error (p>0.05) across exercise intensities or stimulus speeds. High‐intensity exercise is associated with poorer CAT performance. However, stimulus speed plays a key role within this association where faster stimulus speeds were associated with a more marked decrease in coincidence anticipation performance.
Redistributive Taxation in the Roy Model*
Authors: Rothschild Casey , Scheuer Florian
Published: December 2012

We consider optimal redistribution in a model where individuals can self-select into one of several possible sectors based on heterogeneity in a multidimensional skill vector. We first show that when the government does not observe the sectoral choice or underlying skills of its citizens, the constrained Pareto frontier can be implemented with a single nonlinear income tax. We then characterize this optimal tax schedule. If sectoral inputs are complements, a many-sector model with self-selection leads to optimal income taxes that are less progressive than the corresponding taxes in a standard single-sector model under natural conditions. However, they are more progressive than in canonical multisector economies with discrete types and without occupational choice or overlapping sectoral wage distributions.
Spotlight on the microbes that produce heat shock protein 90-targeting antibiotics
Authors: Piper Peter W. , Millson Stefan H.
Published: December 2012

Heat shock protein 90 (Hsp90) is a promising cancer drug target as a molecular chaperone critical for stabilization and activation of several of the oncoproteins that drive cancer progression. Its actions depend upon its essential ATPase, an activity fortuitously inhibited with a very high degree of selectivity by natural antibiotics: notably the actinomycete-derived benzoquinone ansamycins (e.g. geldanamycin) and certain fungal-derived resorcyclic acid lactones (e.g. radicicol). The molecular interactions made by these antibiotics when bound within the ADP/ATP-binding site of Hsp90 have served as templates for the development of several synthetic Hsp90 inhibitor drugs. Much attention now focuses on the clinical trials of these drugs. However, because microbes have evolved antibiotics to target Hsp90, it is probable that they often exploit Hsp90 inhibition when interacting with each other and with plants. Fungi known to produce Hsp90 inhibitors include mycoparasitic, as well as plant-pathogenic, endophytic and mycorrhizal species. The Hsp90 chaperone may, therefore, be a prominent target in establishing a number of mycoparasitic (interfungal), fungal pathogen–plant and symbiotic fungus–plant relationships. Furthermore the Hsp90 family proteins of the microbes that produce Hsp90 inhibitor antibiotics are able to reveal how drug resistance can arise by amino acid changes in the highly conserved ADP/ATP-binding site of Hsp90.
Usutu virus growth in human cell lines: induction of and sensitivity to type I and III interferons
Authors: Scagnolari Carolina , Caputo Beniamino , Trombetti Simona , Cacciotti Giulia , Soldà Annalisa , Spano Lucia , Villari Paolo , della Torre Alessandra , Nowotny Norbert , Antonelli Guido
Published: December 2012

The mechanisms of Usutu virus (USUV) pathogenesis are largely unknown. The aim of this study was to evaluate the sensitivity of USUV to interferon (IFN) and the capacity of USUV to stimulate IFN production. Initial experiments were conducted to characterize the susceptibility of human cell lines to USUV infection and to evaluate the single-growth cycle replication curve of USUV. Results indicate that USUV is able to infect a variety of human cell lines, completing the replication cycle in Hep-2 and Vero cells within 48 h. Pre-treatment of cells with types I and III IFNs significantly inhibited the replication of USUV. However, the inhibitory effects of IFNs were considerably less if IFN was added after viral infection had been initiated. Also, USUV weakly induced types I and III IFNs.
Dahlia latent viroid: a recombinant new species of the family Pospiviroidae posing intriguing questions about its origin and classification
Authors: Verhoeven Jacobus Th. J. , Meekes Ellis T. M. , Roenhorst Johanna W. , Flores Ricardo , Serra Pedro
Published: December 2012

A viroid-like RNA has been detected in two asymptomatic dahlia accessions by return and double PAGE. It appeared smaller than Chrysanthemum stunt viroid and Potato spindle tuber viroid, the two members of the genus Pospiviroid, family Pospiviroidae, reported in this ornamental previously. RT-PCR with primers designed for amplifying all pospiviroids produced no amplicons, but RT-PCR with random primers revealed a 342 nt RNA. The sequence of this RNA was confirmed with specific primers, which additionally revealed its presence in many dahlia cultivars. The RNA was named Dahlia latent viroid (DLVd) because it replicates autonomously, but symptomlessly, in dahlia and shares maximum sequence identity with other viroids of less than 56 %. Furthermore, DLVd displays characteristic features of the family Pospiviroidae: a predicted rod-like secondary structure of minimum free energy with a central conserved region (CCR), and the ability to form the metastable structures hairpins I and II. Its CCR is identical to that of Hop stunt viroid (HSVd, genus Hostuviroid). However, DLVd: (i) has the terminal conserved region present in members of the genus Pospiviroid, but absent in HSVd, and (ii) lacks the terminal conserved hairpin present in HSVd. Phylogenetic reconstructions indicate that HSVd and Pepper chat fruit viroid (genus Pospiviroid) are the closest relatives of DLVd, but DLVd differs from these viroids in its host range, restricted to dahlia so far. Therefore, while DLVd fulfils the criteria to be a novel species of the family Pospiviroidae, its recombinant origin makes assignment to the genera Pospiviroid or Hostuviroid problematic.
Establishment of a reverse genetics system for Schmallenberg virus, a newly emerged orthobunyavirus in Europe
Authors: Elliott Richard M. , Blakqori Gjon , van Knippenberg Ingeborg C. , Koudriakova Elina , Li Ping , McLees Angela , Shi Xiaohong , Szemiel Agnieszka M.
Published: December 2012

Schmallenberg virus (SBV) is a newly emerged orthobunyavirus that has caused widespread disease in cattle, sheep and goats in Europe. Like other orthobunyaviruses, SBV is characterized by a tripartite negative-sense RNA genome that encodes four structural and two non-structural proteins. This study showed that SBV has a wide in vitro host range, and that BHK-21 cells are a convenient host for both SBV propagation and assay by plaque titration. The SBV genome segments were cloned as cDNA and a three-plasmid rescue system was established to recover infectious virus. Recombinant virus behaved similarly in cell culture to authentic virus. The ORF for the non-structural NSs protein, encoded on the smallest genome segment, was disrupted by introduction of translation stop codons in the appropriate cDNA, and when this plasmid was used in reverse genetics, a recombinant virus that lacked NSs expression was recovered. This virus had reduced capacity to shut-off host-cell protein synthesis compared with the wild-type virus. In addition, the NSs-deleted virus induced interferon (IFN) in cells, indicating that, like other orthobunyaviruses, NSs functions as an IFN antagonist, most probably by globally inhibiting host-cell metabolism. The development of a robust reverse genetics system for SBV will facilitate investigation of its pathogenic mechanisms as well as the creation of attenuated strains that could be candidate vaccines.
ReX.Cell: a user-friendly program for powder diffraction indexing
Authors: Bortolotti Mauro , Lonardelli Ivan
Published: December 2012

ReX.Cellis a novel software package dedicated to the automation of crystal cell indexing starting from powder diffraction data. The program aims to help both novice and experienced powder diffractionists overcome the practical difficulties encountered during powder data indexing, by offering a user-friendly highly interactive interface to classical indexing engines. The software provides a wizard-style approach, accompanying the user through all the typical steps of the indexing procedure: preliminary data processing, background subtraction, data smoothing, peak finding and finally autoindexing. Each step can be carried out automatically or fine-tuned through custom options; in either mode, algorithms and filters are applied in real time to the diffraction data, giving an immediate visual feedback. The program is written in the Java programming language and runs on several different operating systems; source code is provided to allow developers to add support for additional indexing programs and/or powder diffraction data formats.
Advances in exploiting preferred orientation in the structure analysis of polycrystalline materials
Authors: Grässlin Jürgen , McCusker Lynne B. , Baerlocher Christian , Gozzo Fabia , Schmitt Bernd , Lutterotti Luca
Published: December 2012

In an attempt to overcome the reflection overlap problem, which is the primary hindrance to structure determination from powder diffraction data, an experimental approach that exploits preferred orientation was developed some years ago. Now both the experimental setup and the data analysis procedure have been optimized, with the result that the quality of the extracted reflection intensities has been improved significantly and the synchrotron beamtime required for the data collection reduced. The one-dimensional Si microstrip detector Mythen II on the Materials Science beamline at the Swiss Light Source and new features in the data analysis softwareMAUD[Lutterotti, Matthies & Wenk (1999).IUCr Commission on Powder Diffraction Newsletter, No. 21, pp. 14–15] have made these improvements possible. The main changes in the experimental setup are (1) using an optimized set of sample orientations, (2) placing the detector such that both positive and negative 2θ angles are measured simultaneously, and (3) introducing an additional sample tilt angle, to measure data that cannot be accessed otherwise. On the data analysis side, the programMAUDis now used for both the determination of the orientation of the crystallites and the intensity extraction. The evaluation of data obtained from a textured zirconium phosphate pyridinium sample shows a significant improvement in the reliability of the structure factor amplitudes derived from overlapping reflections.
Focusing neutrons with a combination of parabolic and elliptical supermirrors
Authors: Désert Sylvain , Panzner Tobias , Permingeat Patrice
Published: December 2012

Cold-neutron focusing is a challenge with regard to improving the flux at the sample, decreasing measurement time and/or gaining statistical reliability. Several techniques are used for neutron focusing, such as simple or multi-beam collimation, refractive or magnetic lenses, and focusing mirrors. In this work, a new device for focusing neutrons using a combination of a parabolic supermirror, an asymmetric slit system and an elliptical supermirror is presented. The aim of this focusing system is to improve the neutron flux at the sample compared to other techniques without either achromatism or absorption. The performance of the device obtained by simulations and measurements with a prototype on a small-angle neutron scattering setup shows a flux gain of four at the sample position and an intensity gain higher than 100 when the sample size can be increased compared to classical setups. Finally the applications for neutron instruments are commented on.
An anisaldehyde sodium bisulfite derivative: poly[[μ4-(hydroxy)(4-methoxyphenyl)methanesulfonato]sodium]
Authors: Díaz de Vivar M. Enriqueta , Baggio Sergio , Baggio Ricardo
Published: December 2012

The title complex, [Na(C8H9O5S)]n, is polymeric and consists of broad layers parallel to (100) made up of an inner hydrophilic core of Na+cations and polar SO3C(OH)– groups, padded on both sides by two hydrophobic layers of pendant methoxyphenyl groups. The Na+cations in the inner core are six-coordinated into highly distorted NaO6octahedra by four symmetry-related (hydroxy)(4-methoxyphenyl)methanesulfonate anions, leading to a tightly woven two-dimensional structure. While there are some hydrogen bonds providing interplanar cohesion, interactions between adjacent layers are weak hydrophobic ones. The present compound appears to be the first reported structure containing the (hydroxy)(4-methoxyphenyl)methanesulfonate ligand.
Second Generation Wire Development at AMSC
Authors: Rupich Martin , Li Xiaoping , Sathyamurthy Srivatsan , Thieme Cornelis , DeMoranville Kenneth , Gannon John , Fleshler Steven
Published: December 2012

AMSC has established a Second Generation (2G) High-Temperature Superconductor (HTS) wire manufacturing technology based on the Rolling Assisted Biaxially Textured Substrate and Metal Organic Deposition processes. AMSC's 2G wire (Amperium) has been used by a wide range of customers for development and testing of initial commercial HTS-based applications. Although the Amperium wire properties and quantities satisfy the requirements for these initial projects, improvements in critical current, field performance, and cost are beneficial for large-scale commercial and military applications. As Amperium wire manufacturing continues to ramp up, AMSC's R&D program has focused on increasing critical current, and the development of nonmagnetic substrates. The R&D process developed for a single-coat, 1.2 μm YBCO film has been transferred to production-scale equipment, resulting in the first Amperium wires with critical currents reaching 500 A/cm-w (77 K, self-field) in production length. A nonmagnetic substrate, which minimizes ferromagnetic substrate losses in ac cable applications, has been produced in R&D lengths and demonstrated in an Amperium cable wire.
Foil Bearing Design Guidelines for Improved Stability
Authors: Schiffmann J. , Spakovszky Z. S.
Published: December 2012

Experimental evidence in the literature suggests that foil bearing-supported rotors can suffer from subsynchronous vibration. While dry friction between top foil and bump foil is thought to provide structural damping, subsynchronous vibration is still an unresolved issue. The current paper aims to shed new light onto this matter and discusses the impact of various design variables on stable foil bearing-supported rotor operation. It is shown that, while a time domain integration of the equations of motion of the rotor coupled with the Reynolds equation for the fluid film is necessary to quantify the evolution of the rotor orbit, the underlying mechanism and the onset speed of instability can be predicted by coupling a reduced order foil bearing model with a rigid-body, linear, rotordynamic model. A sensitivity analysis suggests that structural damping has limited effect on stability. Further, it is shown that the location of the axial feed line of the top foil significantly influences the bearing load capacity and stability. The analysis indicates that the static fluid film pressure distribution governs rotordynamic stability. Therefore, selective shimming is introduced to tailor the unperturbed pressure distribution for improved stability. The required pattern is found via multiobjective optimization using the foil bearing-supported rotor model. A critical mass parameter is introduced as a measure for stability, and a criterion for whirl instability onset is proposed. It is shown that, with an optimally shimmed foil bearing, the critical mass parameter can be improved by more than two orders of magnitude. The optimum shim patterns are summarized for a variety of foil bearing geometries with different L/D ratios and different degrees of foil compliance in a first attempt to establish more general guidelines for stable foil bearing design. At low compressibility (Λ < 2), the optimum shim patterns vary little with bearing geometry; thus, a generalized shim pattern is proposed for low compressibility numbers.
Bearing Multiple Defects Detection Based on Envelope Detector Time Constant
Authors: Mohammadi A. , Safizadeh M. S.
Published: December 2012

Rolling element bearing damage detection is one of the foremost concerns in rotating machinery. The difficulties in bearing defect diagnosis when the bearing has multiple defects increase, since unexpected changes occur in the amplitude of the bearing defect frequencies. In addition, the tendency toward condition-based maintenance (CBM) requires a better understanding of the fault progression due to the fact that multiple defects is one kind of fault development. In this paper, in order to detect multiple defects on one component of the bearing, a new method based on the high frequency resonance technique (HFRT) is introduced. The time constant in the envelope detector is used to find the pattern of the amplitude of defect frequency harmonics (ADFH) in the frequency domain. This method is based on a comparison of the ADFH with a curve, which is obtained from vibration modeling of the bearing. Two criteria are given for the diagnosis of multiple defects. The method is investigated with a simulation and a real experiment. Single and multiple defects are created on the outer race of the ball bearing at different angles. Additionally, the ADFH in the multiple faults experiments are calculated with the proposed mathematical modeling in order to check the accuracy of the model. The experimental results confirm the ability of the proposed method to diagnose multiple defects.