bluuebunny/crossref_metadata_2025 huggingface dataset:
Further exploration of Galactic disk abundance gradients
Authors: Milingo Jackie B. , Henry Richard B. C. , Kwitter Karen B. , Balick Bruce
Published: August 2012

We examine the abundance gradient in the Milky Way disk via homogeneously determined data for 124 Galactic planetary nebulae (PNe). We present recent results from a detailed regression analysis of the O gradient. With O, Ne, S, Cl, and Ar available and a range of galactocentric distance (Rg) from 0.9 to 21 kpc, we present additional exploration of the disk radial gradient by statistically analyzing a series of short segments of increasing average Rg.
Morphological and kinematical analysis of the planetary nebula Hu 1-2 and its irradiated bow-shocks
Authors: Miranda Luis F. , Blanco Mónica , Guerrero Martín A. , Riera Angels
Published: August 2012

We present narrow-band optical and near-IR images, and high-resolution long-slit spectra of the planetary nebula Hu 1-2 that allow us to make a detailed description of its unusual morphology and internal kinematics. The data also reveal that the ansae of Hu 1-2 probably represent bow-shocks associated to high velocity outflows that are irradiated from the central star.
A 3D view of the planetary nebula NGC 40
Authors: Monteiro Hektor , Falceta-Gonçalves Diego
Published: August 2012

We present the results of a study of the planetary nebula NGC 40 with the use of the 3-D photoionization code Mocassin constrained by observational data of different types. The modeling process allows us to derive the three-dimensional nebular structure, physical and chemical characteristics and ionizing star parameters of the object by simultaneously fitting the integrated line intensities, the temperature map, density map, and the observed morphologies in different emission lines. For this particular case we combined hydrodynamical simulations with the photoionization scheme in order to obtain a self-consistent distribution of density and velocity of the nebular material. Finally, using theoretical evolutionary tracks of intermediate and low mass stars, we estimate the mass and age of the central star of NGC 40 as being 0.57 M⊙ and 5810 yr, respectively. The distance obtained from the fitting procedure was 1150 ± 170 pc.
Mapping the physical and chemical properties of the planetary nebula NGC 3242
Authors: Monteiro Hektor , Gonçalves Denise , Leal-Ferreira Marcelo , Corradi Romano , Sánchez Sebastian
Published: August 2012

We present optical integral field spectroscopy analysis of the main components, with the exception of the halo, as well as of the detected small-scale structures of the planetary nebulae NGC 3242. The observations were obtained with the VIMOS instrument attached to VLT-UT3. Spatially resolved maps of the electronic density (Ne), temperatures (Te) and chemical abundances, i.e., in a pixel to pixel fashion of the small and large-scales structures of this planetary nebula are determined in this work. These diagnostic and abundance maps represent important constraints for future detailed three dimensional photoionization modeling of the nebula, as well as providing important information on biases introduced by traditional slit observations.
Morphokinematic properties of the 21 micron source IRAS 22272+5435
Authors: Nakashima Jun-ichi , Kwok Sun , Yung Bosco H. K. , Zhang Yong , Koning Nico , Volgenau Nikolaus
Published: August 2012

We obtained a high-resolution CO map of IRAS 22272+5435 in the CO J = 2–1 line using CARMA. The target exhibits a second biggest angular size of the circumstellar molecular envelope among known 21 μm sources. In the preliminary results, we found that the CO properties of IRAS 22272+5435 is clearly different from those of IRAS 07134+1005, which is another well-investigated 21 μm source. For example, elongations seen in the mid-infrared and CO images are extended in mutually perpendicular directions, although in case of IRAS 07134+1005 the CO feature coincides well with the mid-infrared structure.
NGC 6302: high-ionization permitted lines. Applying X-SSN synthesis to VLT-UVES spectra
Authors: Péquignot Daniel , Morisset Christophe , Casassus Simon
Published: August 2012

A preliminary VLT-UVES spectrum of NGC 6302 (Casassus et al. 2002, MN), which hosts one of the hottest PN nuclei known (Teff ~ 220000 K; Wright et al. 2011, MN), has been recently analysed by means of X-SSN, a spectrum synthesis code for nebulae (Morisset and Péquignot). Permitted recombination lines from highly-ionized species are detected/identified for the first time in a PN, and some of them probably for the first time in (astro)physics. The need for a homogeneous, high signal-to-noise UVES spectrum for NGC 6302 is advocated.
The radio continuum from a planetary nebula as a mirror of the central star evolution
Authors: Sharova Olga I.
Published: August 2012

In the frame of ISW model the rates of the evolutionary changes of the flux density and the critical frequency in radio continuum spectrum have been calculated in dependence on the kinematic age of a planetary nebula. The time changes of the instantaneous radio spectra of IC 418 and NGC 6369 do not contradict accounts.
UV-NIR spectra of two planetary nebulae with X-Shooter
Authors: Szyszka Cezary , Walsh Jeremy R. , Zijlstra Albert A.
Published: August 2012

The ESO VLT spectrograph X-shooter is currently the only one capable of observing the range from 330 nm up to 2.5 μm in a single shot. X-shooter is very suitable for study of the many diagnostic emission lines in PN providing a uniform flux scale at medium resolution over a large instantaneous wavelength range. Spectroscopy of two contrasting PNe, NGC 6302 and M 2-9, were observed and methods explored for identification of the many fitted emission lines.
Radial density profiles of PNe halos from numerical models of mass-loss history
Authors: Verbena Juan-Luis , Schröder Klaus-Peter , Wachter Astrid
Published: August 2012

We review the stellar mass loss of red giants and tip-AGB objects analizing the variation in the outflow velocity for different mass models (Wachter et al. 2002). We approach the superwind problem and see the evolution of tip-AGB stars via previously made mass-loss histories that are consistent with the Weidemann initial-final mass relationship (for carbon-rich stars). Finally density profiles are produced from these mass-loss histories, and the corresponding line-of-sight integration is compared with observational data (Phillips et al. 2009). We note the resemblance between the results obtained with our models and the observational data. We are thus able to reproduce the general trends of the emission from simple models (see Verbena et al. 2011).
Signatures of pulsations and mass loss in the spectra of post-AGB stars
Authors: Začs Laimons , Sperauskas Julius , Laure Aija , Smirnova Olesja
Published: August 2012

The results of high-resolution spectroscopy and radial velocity monitoringa are presented for selected post-AGB candidate stars. Time series of high-resolution spectra for HD235858 shows spliting of low-excitation atomic lines and significant changes in the intensity of C2 and CN lines originated in the extended atmosphere significantly affected by pulsations and outflow. Mass ejection was confirmed for cool R CrB candidate stars DY Per, V1983 Cyg, and V2074 Cyg.
Planetary nebulae detected in the Spitzer Space Telescope GLIMPSE 3D Legacy Survey
Authors: Zhang Yong , Kwok Sun , Hsia Chih-Hao , Nakashima Jun-ichi , Koning Nico
Published: August 2012

Due to interstellar extinction, optical census of Galactic planetary nebulae (PNs) is highly incomplete, and some compact H ii regions might have been mis-classified as PNs. The problem is particularly severe in the Galactic plane where the extinction in the optical is significant and hampers the detections of PNs. Unlike optical observations, infrared (IR) observations are hardly affected by interstellar extinction, and provide a good opportunity to study highly obscured PNs. In this study, we use the data from the Spitzer Legacy Infrared Mid-Plane Survey Extraordinaire 3D (GLIMPSE 3D) to investigate the mid-infrared (MIR) properties of PNs and PN candidates.
Sizing up metatranscriptomics
Authors: Moran Mary Ann , Satinsky Brandon , Gifford Scott M , Luo Haiwei , Rivers Adam , Chan Leong-Keat , Meng Jun , Durham Bryndan P , Shen Chen , Varaljay Vanessa A , Smith Christa B , Yager Patricia L , Hopkinson Brian M
Published: August 2012

A typical marine bacterial cell in coastal seawater contains only ∼200 molecules of mRNA, each of which lasts only a few minutes before being degraded. Such a surprisingly small and dynamic cellular mRNA reservoir has important implications for understanding the bacterium’s responses to environmental signals, as well as for our ability to measure those responses. In this perspective, we review the available data on transcript dynamics in environmental bacteria, and then consider the consequences of a small and transient mRNA inventory for functional metagenomic studies of microbial communities.
TLR2 and TLR4 activation induces p38 MAPK‐dependent phosphorylation of S6 kinase 1 in C2C12 myotubes
Authors: Zbinden‐Foncea Hermann , Deldicque Louise , Pierre Nicolas , Francaux Marc , Raymackers Jean‐Marc
Published: August 2012

Toll‐like receptors 2 (TLR2) and 4 (TLR4) are present in the plasma membrane of skeletal muscle cells where their functions remain incompletely resolved. They can bind various extracellular ligands, such as FSL‐1, lipopolysaccharide (LPS) and/or palmitic acid (PA). We have investigated the link between PA, TLR2/4 and ribosomal S6 kinase 1 (S6K1) in C2C12 myotubes. Incubation with agonists of either TLR2 or TLR4, and with a high concentration of PA, increased S6K1 phosphorylation. Canonical upstream kinases of S6K1, protein kinase B (PKB) and mammalian target of rapamycin complex 1 (mTORC1), were regulated in the opposite way by PA, indicating that these kinases were probably not involved. By using the SB202190 inhibitor, p38 MAPK (mitogen‐activated protein kinase) was found to be a key mediator of PA‐induced phosphorylation of S6K1. Downregulation of either tlr2 or tlr4 gene expression by small interfering RNAs prevented the activation of both p38 MAPK and S6K1 by FSL‐1, LPS or PA. Thus TLR2 and TLR4 agonists can increase the level of S6K1 phosphorylation in a p38 MAPK‐dependent way in C2C12 myotubes. As PA induced the same intracellular signalling, a novel atypical pathway for PA is induced at the cellular membrane level and results in a higher phosphorylation state of S6K1.
Diagnosing postural tachycardia syndrome: comparison of tilt testing compared with standing haemodynamics
Authors: Plash Walker B. , Diedrich André , Biaggioni Italo , Garland Emily M. , Paranjape Sachin Y. , Black Bonnie K. , Dupont William D. , Raj Satish R.
Published: August 2012

POTS (postural tachycardia syndrome) is characterized by an increased heart rate (ΔHR) of ≥30 bpm (beats/min) with symptoms related to upright posture. Active stand (STAND) and passive head-up tilt (TILT) produce different physiological responses. We hypothesized these different responses would affect the ability of individuals to achieve the POTS HR increase criterion. Patients with POTS (n=15) and healthy controls (n=15) underwent 30 min of tilt and stand testing. ΔHR values were analysed at 5 min intervals. ROC (receiver operating characteristic) analysis was performed to determine optimal cut point values of ΔHR for both tilt and stand. Tilt produced larger ΔHR than stand for all 5 min intervals from 5 min (38±3 bpm compared with 33±3 bpm; P=0.03) to 30 min (51±3 bpm compared with 38±3 bpm; P<0.001). Sn (sensitivity) of the 30 bpm criterion was similar for all tests (TILT10=93%, STAND10=87%, TILT30=100%, and STAND30=93%). Sp (specificity) of the 30 bpm criterion was less at both 10 and 30 min for tilt (TILT10=40%, TILT30=20%) than stand (STAND10=67%, STAND30=53%). The optimal ΔHR to discriminate POTS at 10 min were 38 bpm (TILT) and 29 bpm (STAND), and at 30 min were 47 bpm (TILT) and 34 bpm (STAND). Orthostatic tachycardia was greater for tilt (with lower Sp for POTS diagnosis) than stand at 10 and 30 min. The 30 bpm ΔHR criterion is not suitable for 30 min tilt. Diagnosis of POTS should consider orthostatic intolerance criteria and not be based solely on orthostatic tachycardia regardless of test used.
Coercivity and stability results for an extended Navier-Stokes system
Authors: Iyer Gautam , Pego Robert L. , Zarnescu Arghir
Published: August 2012

In this paper, we study a system of equations that is known to extend Navier-Stokes dynamics in a well-posed manner to velocity fields that are not necessarily divergence-free. Our aim is to contribute to an understanding of the role of divergence and pressure in developing energy estimates capable of both controlling the nonlinear terms, and being useful at the time-discrete level. We address questions of global existence and stability in bounded domains with no-slip boundary conditions. Through use of new H1 coercivity estimates for the linear equations, we establish a number of global existence and stability results, including results for small divergence and a time-discrete scheme. We also prove global existence in 2D for any initial data, provided sufficient divergence damping is included.
Molecular layers of ZnPc and FePc on Au(111) surface: Charge transfer and chemical interaction
Authors: Ahmadi Sareh , Shariati M. Nina , Yu Shun , Göthelid Mats
Published: August 2012

We have studied zinc phthalocyanine (ZnPc) and iron phthalocyanine (FePc) thick films and monolayers on Au(111) using photoelectron spectroscopy and x-ray absorption spectroscopy. Both molecules are adsorbed flat on the surface at monolayer. ZnPc keeps this orientation in all investigated coverages, whereas FePc molecules stand up in the thick film. The stronger inter-molecular interaction of FePc molecules leads to change of orientation, as well as higher conductivity in FePc layer in comparison with ZnPc, which is reflected in thickness-dependent differences in core-level shifts. Work function changes indicate that both molecules donate charge to Au; through the π-system. However, the Fe3d derived lowest unoccupied molecular orbital receives charge from the substrate when forming an interface state at the Fermi level. Thus, the central atom plays an important role in mediating the charge, but the charge transfer as a whole is a balance between the two different charge transfer channels; π-system and the central atom.
Vapor-liquid interfacial properties of rigid-linear Lennard-Jones chains
Authors: Blas F. J. , Ignacio Moreno-Ventas Bravo A. , Míguez J. M. , Piñeiro M. M. , MacDowell L. G.
Published: August 2012

We have obtained the interfacial properties of short rigid-linear chains formed from tangentially bonded Lennard-Jones monomeric units from direct simulation of the vapour-liquid interface. The full long-range tails of the potential are accounted for by means of an improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)]10.1021/jp056344z proposed recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)]10.1063/1.3197009 valid for spherical as well as for rigid and flexible molecular systems. Three different model systems comprising of 3, 4, and 5 monomers per molecule are considered. The simulations are performed in the canonical ensemble, and the vapor-liquid interfacial tension is evaluated using the test-area method. In addition to the surface tension, we also obtain density profiles, coexistence densities, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the chain length and rigidity on these properties. According to our results, the main effect of increasing the chain length (at fixed temperature) is to sharpen the vapor-liquid interface and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness decreases and the surface tension increases as the molecular chains get longer. The surface tension has been scaled by critical properties and represented as a function of the difference between coexistence densities relative to the critical density.
A polyvalent harmonic coil testing method for small-aperture magnets
Authors: Arpaia Pasquale , Buzio Marco , Golluccio Giancarlo , Walckiers Louis
Published: August 2012

A method to characterize permanent and fast-pulsed iron-dominated magnets with small apertures is presented. The harmonic coil measurement technique is enhanced specifically for small-aperture magnets by (1) in situ calibration, for facing search-coil production inaccuracy, (2) rotating the magnet around its axis, for correcting systematic effects, and (3) measuring magnetic fluxes by stationary coils at different angular positions for measuring fast pulsed magnets. This method allows a quadrupole magnet for particle accelerators to be characterized completely, by assessing multipole field components, magnetic axis position, and field direction. In this paper, initially the metrological problems arising from testing small-aperture magnets are highlighted. Then, the basic ideas of the proposed method and the architecture of the corresponding measurement system are illustrated. Finally, experimental validation results are shown for small-aperture permanent and fast-ramped quadrupole magnets for the new linear accelerator Linac4 at CERN (European Organization for Nuclear Research).
Ethanol (C2H5OH) spray of sub-micron droplets for laser driven negative ion source
Authors: Prasad R. , Borghesi M. , Abicht F. , Nickles P. V. , Stiel H. , Schnürer M. , Ter-Avetisyan S.
Published: August 2012

Liquid ethanol (C2H5OH) was used to generate a spray of sub-micron droplets. Sprays with different nozzle geometries have been tested and characterised using Mie scattering to find scaling properties and to generate droplets with different diameters within the spray. Nozzles having throat diameters of 470 μm and 560 μm showed generation of ethanol spray with droplet diameters of (180 ± 10) nm and (140 ± 10) nm, respectively. These investigations were motivated by the observation of copious negative ions from these target systems, e.g., negative oxygen and carbon ions measured from water and ethanol sprays irradiated with ultra-intense (5 × 1019 W/cm2), ultra short (40 fs) laser pulses. It is shown that the droplet diameter and the average atomic density of the spray have a significant effect on the numbers and energies of accelerated ions, both positive and negative. These targets open new possibilities for the creation of efficient and compact sources of different negative ion species.
Partial-transfer absorption imaging: A versatile technique for optimal imaging of ultracold gases
Authors: Ramanathan Anand , Muniz Sérgio R. , Wright Kevin C. , Anderson Russell P. , Phillips William D. , Helmerson Kristian , Campbell Gretchen K.
Published: August 2012

Partial-transfer absorption imaging is a tool that enables optimal imaging of atomic clouds for a wide range of optical depths. In contrast to standard absorption imaging, the technique can be minimally destructive and can be used to obtain multiple successive images of the same sample. The technique involves transferring a small fraction of the sample from an initial internal atomic state to an auxiliary state and subsequently imaging that fraction absorptively on a cycling transition. The atoms remaining in the initial state are essentially unaffected. We demonstrate the technique, discuss its applicability, and compare its performance as a minimally destructive technique to that of phase-contrast imaging.
The impact of inertial effects on solute dispersion in a channel with periodically varying aperture
Authors: Bouquain J. , Méheust Y. , Bolster D. , Davy P.
Published: August 2012

We investigate solute transport in channels with a periodically varying aperture, when the flow is still laminar but sufficiently fast for inertial effects to be non-negligible. The flow field is computed for a two-dimensional setup using a finite element analysis, while transport is modeled using a random walk particle tracking method. Recirculation zones are observed when the aspect ratio of the unit cell and the relative aperture fluctuations are sufficiently large; under non-Stokes flow conditions, the flow in non-reversible, which is clearly noticeable by the horizontal asymmetry in the recirculation zones. After characterizing the size and position of the recirculation zones as a function of the geometry and Reynolds number, we investigate the corresponding behavior of the longitudinal effective diffusion coefficient. We characterize its dependence on the molecular diffusion coefficient Dm, the Péclet number, the Reynolds number, and the geometry. The proposed relation is a generalization of the well-known Taylor-Aris relationship relating the longitudinal dispersion coefficient to Dm and the Péclet number for a channel of constant aperture at sufficiently low Reynolds number. Inertial effects impact the exponent of the Péclet number in this relationship; the exponent is controlled by the relative amplitude of aperture fluctuations. For the range of parameters investigated, the measured dispersion coefficient always exceeds that corresponding to the parallel plate geometry under Stokes conditions; in other words, boundary fluctuations always result in increased dispersion. The transient approach to the asymptotic regime is also studied and characterized quantitatively. We show that the measured characteristic time to attain asymptotic conditions is controlled by two competing effects: (i) the trapping of particles in the near-immobile zone and, (ii) the enhanced mixing in the central zone where most of the flow takes place (mainstream), due to its thinning.
Analysis of the “3-Omega” method for substrates and thick films of anisotropic thermal conductivity
Authors: Ramu Ashok T. , Bowers John E.
Published: August 2012

The heat equation in an anisotropic material under sinusoidal excitation is solved in cylindrical-polar coordinates for the geometry conventionally used in the measurement of thermal conductivity by the “3-Omega” method. Although the solution can be carried out in Cartesian coordinates using Fourier transforms, the inverse transforms have to be evaluated numerically. The current method allows us to make contact with, and extend, the analytical results of Cahill and Pohl for isotropic substrates. We find that the 3-Omega method experiment, if performed conventionally, measures the average thermal conductivity in the in-plane and cross-plane directions, for modest anisotropies. An alternate geometry with separate heater and thermometer lines is explored, where the temperature of the thermometer is expected on physical grounds to be selectively sensitive to the in-plane thermal conductivity. The selectivity is quantified using the analytic forms derived for the temperature profile, and the results are verified by finite element method simulations.
Modeling of dielectric and piezoelectric response of 1-3 type piezocomposites
Authors: Jayendiran R. , Arockiarajan A.
Published: August 2012

A study is carried out to compare the non-linear behaviour of 1-3 piezocomposites with different volume fractions and bulk piezoceramics. Experiments are conducted to measure the electrical displacement and strain on piezocomposites and ceramics under high cyclic electrical loading. A thermodynamically consistent framework, combining the phenomenological and micromechanical models, is developed to predict the coupled behavior. Volume fractions of three distinct uni-axial variants (instead of six variants) are used as internal variables to describe the microscopic state of the material. In this model, the grain boundary effects are taken into account by introducing the back fields (electric field and stress) as non-linear kinematic hardening functions. In order to calculate the effective properties (elastic, piezoelectric, and dielectric constants) of piezocomposites for different volume fractions, an analytical model based on equivalent layered approach is proposed. The predicted effective properties are incorporated in the proposed model, and the classical hysteresis (electrical displacement versus electric field) as well as butterfly curves (strain versus electric field) is simulated. Comparison between the experiments and the simulations shows that this model can reproduce the characteristics of non-linear coupled response. It is observed that the variation in fiber volume fraction has a significant influence on the response of the 1-3 piezocomposites.
Magnetic and dielectric properties of sol-gel derived nanoparticles of double perovskite Y2NiMnO6
Authors: Maiti R. P. , Dutta S. , Mukherjee M. , Mitra M. K. , Chakravorty Dipankar
Published: August 2012

Nanoparticles of Y2NiMnO6 having diameters around 20 nm were synthesized by a sol-gel method. X-ray data were analysed by Rietveld method. This showed the crystals to have monoclinic structure. X-ray photoelectron spectroscopy studies showed a ratio of Mn3+/Mn4+ equal to 0.64 to be present in the nanocrystals. A small polaron hopping conduction model was found to satisfactorily explain the electrical resistivity behaviour of the samples. The latter exhibited ferromagnetic (FM) properties with a Curie temperature around 92 K. This behaviour was ascribed to a ferromagnetic superexchange interaction between Mn4+ and Ni2+ ions. Spin glass behaviour was ruled out on the basis of ac magnetic susceptibility data. The nanocrystals exhibited a peak in the dielectric constant at a temperature 535 K indicating a ferroelectric transition. This is consistent with the recent theoretical prediction made on the basis of density functional calculations.
Bioparticles assembled using low frequency vibration immune to evacuation drifts
Authors: Shao Fenfen , Whitehill James David , Ng Tuck Wah
Published: August 2012

The use of low frequency vibration on suspensions of glass beads in a droplet has been shown to develop a strong degree of patterning (to a ring) due to the manner with which the surface waves are modified. Functionalized glass beads that serve as bioparticles permit for sensitive readings when concentrated at specific locations. However, a time controlled exposure with analytes is desirable. The replacement of the liquid medium with analyte through extraction is needed to conserve time. Nevertheless, we show here that extraction with a porous media, which is simple and useable in the field, will strongly displace the patterned beads. The liquid removal was found to be dependent on two mechanisms that affect the shape of the droplet, one of contact hysteresis due to the outer edge pinning, and the other of liquid being drawn into the porous media. From this, we developed and demonstrated a modified well structure that prevented micro-bead displacement during evacuation. An added strong advantage with this approach lies with its ability to require only analytes to be dispensed at the location of aggregated particles, which minimizes analyte usage. This was analytically established here.
Thermal conductivity calculation of complex (dusty) plasmas
Authors: Shahzad Aamir , He Mao-Gang
Published: August 2012

The thermal conductivity of three-dimensional (3D) strongly coupled complex (dusty) plasmas has been calculated through the improved Evan-Gillan nonequilibrium molecular dynamics (NEMD) algorithm. The extensive NEMD simulations are performed to study the performance of the algorithm and compared the results determined for perturbed heat energy current to the results obtained by equilibrium molecular dynamics (EMD) simulations. The calculations show that the present algorithm gives accurate results with fast convergence and small size effects over a wide range of plasma coupling and screening parameters. The present simulation results are in agreement with part of others NEMD and EMD data in the literature with simulation values generally overpredicting the thermal conductivity by 3%–20%, depending on plasma parameters. It is shown that the homogenous perturbed method can be employed to estimate the thermal conductivity and to understand the fundamental behaviors in 3D complex Yukawa liquids.
Characterizing the dynamics of higher dimensional nonintegrable conservative systems
Authors: Manchein Cesar , Beims Marcus W. , Rost Jan M.
Published: August 2012

The phase space dynamics of higher dimensional nonintegrable conservative systems is characterized via the effect of “sticky” motion on the finite time Lyapunov exponents (FTLEs) distribution. Since a chaotic trajectory suffers the sticky effect when chaotic motion is mixed to the regular one, it offers a way to separate the mixed from the totally chaotic regimes. To detect stickiness, four different measures are used, related to the distributions of the positive FTLEs, and provide conditions to characterize the dynamics. Conservative maps are systematically studied from the uncoupled two-dimensional case up to coupled maps of dimension 20. Sticky motion is detected in all unstable directions above a threshold Kd of the nonlinearity parameter K for the high dimensional cases d = 10, 20. Moreover, as K increases we can clearly identify the transition from mixed to totally chaotic motion which occurs simultaneously in all unstable directions. Results show that all four statistical measures sensitively characterize the motion in high dimensional systems.
Simulation of filamentation instability of a current-carrying plasma by particle in cell method
Authors: Niknam A. R. , Mostafavi P. S. , Komaizi D. , Salahshoor M.
Published: August 2012

The nonlinear dynamics of filamentation instability in a weakly ionized current-carrying plasma in the diffusion frequency region is studied using particle in cell simulation. The effects of electron thermal motion and ion-neutral collision on the evolution of this instability in the nonlinear stage of the filaments coalescence are discussed. It is found that the coalescence of the current filaments is enhanced by increasing the temperature and is delayed by increasing the collision frequency.
Emission bands of nitrogen-implantation induced luminescent centers in ZnO crystals: Experiment and theory
Authors: Dai X. M. , Xu S. J. , Ling C. C. , Brauer G. , Anwand W. , Skorupa W.
Published: August 2012

High quality ZnO crystals with the sharp band-edge excitonic emission and very weak green emission were implanted by nitrogen ions. An additional red emission band was observed in the as-implanted ZnO crystal and investigated as a function of temperature. By employing the underdamped multimode Brownian oscillator model for the general electron-phonon coupling system, both the original green and nitrogen-implantation induced red emission bands were theoretically reproduced at different temperatures. Excellent agreement between the theory and the experiment enables us determine the energetic positions of the pure electronic levels associated with the green and red emission bands, respectively. The determined energy level of the red emission band is in good agreement with the data obtained from the deep-level transient spectroscopy measurements.
Electronic, structural, and elastic properties of metal nitrides XN (X = Sc, Y): A first principle study
Authors: Ekuma Chinedu E. , Bagayoko Diola , Jarrell Mark , Moreno Juana
Published: August 2012

We utilized a simple, robust, first principle method, based on basis set optimization with the BZW-EF method, to study the electronic and related properties of transition metal mono-nitrides: ScN and YN. We solved the KS system of equations self-consistently within the linear combination of atomic orbitals (LCAO) formalism. It is shown that the band gap and low energy conduction bands, as well as elastic and structural properties, can be calculated with a reasonable accuracy when the LCAO formalism is used to obtain an optimal basis. Our calculated, indirect electronic band gap (\documentclass[12pt]{minimal}\begin{document}${\rm E}^\mathrm{\Gamma -X}_g$\end{document}EΓ−Xg) is 0.79 (LDA) and 0.88 eV (GGA) for ScN. In the case of YN, we predict an indirect band gap (\documentclass[12pt]{minimal}\begin{document}${\rm E}^\mathrm{\Gamma -X}_g$\end{document}EΓ−Xg) of 1.09 (LDA) and 1.15 eV (GGA). We also calculated the equilibrium lattice constants, the bulk moduli (Bo), effective masses, and elastic constants for both systems. Our calculated values are in excellent agreement with experimental ones where the latter are available.
Autophagy activators rescue and alleviate pathogenesis of a mouse model with proteinopathies of the TAR DNA-binding protein 43
Authors: Wang I-Fang , Guo Bo-Shen , Liu Yu-Chih , Wu Cheng-Chun , Yang Chun-Hung , Tsai Kuen-Jer , Shen Che-Kun James
Published: August 2012

TDP-43 is a multifunctional DNA/RNA-binding protein that has been identified as the major component of the cytoplasmic ubiquitin (+) inclusions (UBIs) in diseased cells of frontotemporal lobar dementia (FTLD-U) and amyotrophic lateral sclerosis (ALS). Unfortunately, effective drugs for these neurodegenerative diseases are yet to be developed. We have tested the therapeutic potential of rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR) and three other autophagy activators (spermidine, carbamazepine, and tamoxifen) in a FTLD-U mouse model with TDP-43 proteinopathies. Rapamycin treatment has been reported to be beneficial in some animal models of neurodegenerative diseases but not others. Furthermore, the effects of rapamycin treatment in FTLD-U have not been investigated. We show that rapamycin treatment effectively rescues the learning/memory impairment of these mice at 3 mo of age, and it significantly slows down the age-dependent loss of their motor function. These behavioral improvements upon rapamycin treatment are accompanied by a decreased level of caspase-3 and a reduction of neuron loss in the forebrain of FTLD-U mice. Furthermore, the number of cells with cytosolic TDP-43 (+) inclusions and the amounts of full-length TDP-43 as well as its cleavage products (35 kDa and 25 kDa) in the urea-soluble fraction of the cellular extract are significantly decreased upon rapamycin treatment. These changes in TDP-43 metabolism are accompanied by rapamycin-induced decreases in mTOR-regulated phospho-p70 S6 kinase (P-p70) and the p62 protein, as well as increases in the autophagic marker LC3. Finally, rapamycin as well as spermidine, carbamazepine, and tamoxifen could also rescue the motor dysfunction of 7-mo-old FTLD-U mice. These data suggest that autophagy activation is a potentially useful route for the therapy of neurodegenerative diseases with TDP-43 proteinopathies.
A Remote‐Sensing, GIS‐Based Approach to Identify, Characterize, and Model Spawning Habitat for Fall‐Run Chum Salmon in a Sub‐Arctic, Glacially Fed River
Authors: Wirth Lisa , Rosenberger Amanda , Prakash Anupma , Gens Rudiger , Margraf F. Joseph , Hamazaki Toshihide
Published: August 2012

At northern limits of a species’ distribution, fish habitat requirements are often linked to thermal preferences, and the presence of overwintering habitat. However, logistical challenges and hydrologic processes typical of glacial systems could compromize the identification of these habitats, particularly in large river environments. Our goal was to identify and characterize spawning habitat for fall‐run chum salmon Oncorhynchus keta and model habitat selection from spatial distributions of tagged individuals in the Tanana River, Alaska using an approach that combined ground surveys with remote sensing. Models included braiding, sinuosity, ice‐free water surface area (indicating groundwater influence), and persistent ice‐free water (i.e., consistent presence of ice‐free water for a 12‐year period according to satellite imagery). Candidate models containing persistent ice‐free water were selected as most likely, highlighting the utility of remote sensing for monitoring and identifying salmon habitat in remote areas. A combination of ground and remote surveys revealed spatial and temporal thermal characteristics of these habitats that could have strong biological implications. Persistent ice‐free sites identified using synthetic aperture radar appear to serve as core areas for spawning fall chum salmon, and the importance of stability through time suggests a legacy of successful reproductive effort for this homing species. These features would not be captured with a one‐visit traditional survey but rather required remote‐sensing monitoring of the sites through time.
A note on *_{𝑤}-Noetherian domains
Authors: Hwang Chul Ju , Lim Jung Wook
Published: August 2012

Let

D
D

be an integral domain with quotient field

K
K

,

∗
*

be a star-operation on

D
D

, and

G

V
∗

(
D
)

GV^*(D)

be the set of finitely generated ideals

J
J

of

D
D

such that

J
∗

=
D

J_*=D

. Then the map

∗
w

*_w

defined by

I

∗
w

=
{
x
∈
K
∣
J
x
⊆
I

I_{*_w}=\{x \in K \mid Jx \subseteq I

for some

J
∈
G

V
∗

(
D
)
}

J \in GV^*(D)\}

for all nonzero fractional ideals

I
I

of

D
D

is a finite character star-operation on

D
D

. In this paper, we study several properties of

∗
w

*_w

-Noetherian domains. In particular, we prove the Hilbert basis theorem for

∗
w

*_w

-Noetherian domains.
Positive solutions of semilinear elliptic equations with small perturbations
Authors: Kajikiya Ryuji
Published: August 2012

In this paper, we study the semilinear elliptic equation with a small perturbation. We assume the main term in the equation to have a mountain pass structure but do not suppose any condition for the perturbation term. Then we prove the existence of a positive solution. Moreover, we prove the existence of at least two positive solutions if the perturbation term is nonnegative.
Interpolation on surfaces in ℙ³
Authors: Huizenga Jack
Published: August 2012

Suppose

S
S

is a surface in

P

3

\mathbb {P}^3

, and

p
1

,
…
,

p
r

p_1,\ldots ,p_r

are general points on

S
S

. What is the dimension of the space of sections of

O

S

(
e
)

\mathcal {O}_S(e)

having singularities of multiplicity

m
i

m_i

at

p
i

p_i

for all

i
i

? We formulate two natural conjectures which would answer this question, and we show they are equivalent. We then prove these conjectures in case all multiplicities are at most

4
4

.
Dimension of slices through the Sierpinski carpet
Authors: Manning Anthony , Simon Károly
Published: August 2012

For Lebesgue typical

(
θ
,
a
)

(\theta ,a)

, the intersection of the Sierpinski carpet

F
F

with a line

y
=
x
tan
⁡
θ
+
a

y=x\tan \theta +a

has (if non-empty) dimension

s
−
1

s-1

, where

s
=
log
⁡
8

/

log
⁡
3
=

dim

H

⁡
F

s=\log 8/\log 3=\dim _\textrm {H}F

. Fix the slope

tan
⁡
θ
∈

Q

\tan \theta \in \mathbb {Q}

. Then we shall show on the one hand that this dimension is strictly less than

s
−
1

s-1

for Lebesgue almost every

a
a

. On the other hand, for almost every

a
a

according to the angle

θ
\theta

-projection

ν
θ

\nu ^\theta

of the natural measure

ν
\nu

on

F
F

, this dimension is at least

s
−
1

s-1

. For any

θ
\theta

we find a connection between the box dimension of this intersection and the local dimension of

ν
θ

\nu ^\theta

at

a
a

.
Agricultural Insurance in Developed Countries: Where Have We Been and Where Are We Going?
Authors: Smith Vincent H. , Glauber Joseph W.
Published: August 2012

Agricultural insurance in developed countries originates in named peril products that were originally offered by private companies approximately two hundred years ago, first in Europe and then in the United States. Today, many agricultural insurance products are offered, most of them heavily subsidized by governments. In the context of developed economies, this article examines the evolution of agricultural insurance products, the economics of the demand and supply sides of agricultural insurance markets, and the economic welfare, political economy, and trade relation implications of private and public agricultural insurance in developed countries.
Pathogen-Induced Accumulation of an Ellagitannin Elicits Plant Defense Response
Authors: Mamaní Alicia , Filippone María Paula , Grellet Carlos , Welin Björn , Castagnaro Atilio Pedro , Ricci Juan Carlos Díaz
Published: August 2012

In an incompatible interaction between Colletotrichum fragariae and strawberry plants, the accumulation of phenolic compounds in plant leaves was observed. A particularly abundant penta-esterified ellagitannin that accumulated in response to pathogen attack was identified as 1-0-galloyl-2,3;4,6-bis-hexahydroxydiphenoyl-β-d-glucopyranose (HeT) by mass spectroscopy and nuclear magnetic resonance. Foliar application of purified HeT prior to inoculation with a virulent pathogen was shown to increase resistance toward C. acutatum in strawberry plants and to Xanthomonas citri subsp. citri in lemon plants. The induced resistance in strawberry was associated with a rapid oxidative burst, callose deposition, a transient increase of salicylic acid in phloem, and induction of gene expression responsive to salicylic acid. Results obtained suggested that HeT could be a common plant defense response molecule capable of inducing pathogen resistance in different plant species.
MASSIVE EXUDATIVE RETINAL DETACHMENT AFTER PHOTODYNAMIC THERAPY FOR PERIPHERAL RETINAL CAPILLARY HEMANGIOMA
Authors: Goto So , Oshima Yusuke , Tsujikawa Motokazu , Nishida Kohji
Published: August 2012

Purpose:

To report a case requiring emergency surgical intervention to treat a progressive massive retinal detachment after photodynamic therapy for a peripheral retinal capillary hemangioma associated with von Hippel-Lindau disease.

Methods:

A 38-year-old woman with von Hippel-Lindau disease had a peripheral retinal capillary hemangioma in the left eye. At the initial visit, the best-corrected visual acuity was 20/250 in the left eye. Photodynamic therapy was applied to treat the hemangioma. After 1 day, a massive retinal detachment and vitreous hemorrhage occurred. Three days after photodynamic therapy, vitrectomy was performed to treat the retinal detachment, which progressed with visual deterioration to hand motions.

Results:

A diagnosis of exudative retinal detachment was made because no retinal breaks were identified. The retina was reattached with external drainage and gas tamponade. One month postoperatively, the best-corrected visual acuity recovered to 20/100 in the left eye, and the vascular activity of the hemangioma stabilized.

Conclusion:

Photodynamic therapy monotherapy to treat retinal capillary hemangioma might result in a massive exudative retinal detachment requiring surgery.
Inactivation of influenza virus haemagglutinin by chlorine dioxide: oxidation of the conserved tryptophan 153 residue in the receptor-binding site
Authors: Ogata Norio
Published: August 2012

Airborne influenza virus infection of mice can be prevented by gaseous chlorine dioxide (ClO2). This study demonstrated that ClO2 abolished the function of the haemagglutinin (HA) of influenza A virus (H1N1) in a concentration-, time- and temperature-dependent manner. The IC50 during a 2 min reaction with ClO2 at 25 °C was 13.7 µM, and the half-life time of HA with 100 µM ClO2 at 25 °C was 19.5 s. Peptides generated from a tryptic digest of ClO2-treated virus were analysed by mass spectrometry. An HA fragment, 150NLLWLTGK157 was identified in which the tryptophan residue (W153) was 32 mass units greater than expected. The W153 residue of this peptide, which is derived from the central region of the receptor-binding site of HA, is highly conserved. It was shown that W153 was oxidized to N-formylkynurenine in ClO2-treated virus. It was concluded that the inactivation of influenza virus by ClO2 is caused by oxidation of W153 in HA, thereby abolishing its receptor-binding ability.
Active ageing in organisations: a case study approach
Authors: Frerichs Frerich , Lindley Robert , Aleksandrowicz Paula , Baldauf Beate , Galloway Sheila
Published: August 2012

Purpose

The purpose of this paper is to review good practice examples which promote recruitment and retention of older workers and/or the employability of workers as they age and to examine pathways of practice.

Design/methodology/approach

Analysis of qualitative data, drawing on a cross‐section selection of 83 good practice case studies in labour organisations in eight European countries: Denmark, France, Germany, Italy, Netherlands, Poland, Sweden and the UK.

Findings

The study presented good practice examples and pathways of practice for the four most frequently found dimensions in the sample (training, lifelong learning and knowledge transfer; flexible working; health protection and promotion and job design; career development and mobility management) as well as examples from small to medium‐sized enterprises (SMEs) (construction) and the public sector (transport) adopting strategies that fall within these dimensions. These examples show that innovative solutions to the challenge of an ageing workforce have been developed with good outcomes, often combining a number of measures, e.g. mobility management, health promotion and knowledge transfer. However, there is an uneven profile of age management debates and company strategies across Europe (with countries such as Germany and the Netherlands being more advanced). There is also some evidence of a standstill or roll‐back of measures during an economic crisis.

Originality/value

The paper reviews organisational measures facilitating the extension of working lives, of which many are longstanding and include sectors previously underrepresented in good practice databases (SMEs, public sector).
Active ageing in Europe: the role of organisations
Authors: Henkens Kène , Schippers Joop
Published: August 2012

Purpose

The purpose of this paper (overview) is to provide a brief introduction to the topic of active ageing and summarise the seven studies included in this special issue. The authors also acknowledge those who were instrumental in bringing this issue to fruition.

Design/methodology/approach

The International Journal of Manpower's usual double‐blind review process was used to select the seven papers included in this special issue. The papers themselves all have a cross‐national perspective using data from eight European countries. These papers represent a wide variety of designs, methodologies and analytic strategies used to study active ageing in the paid labour force as well as in civil society. The papers make use of large‐scale surveys among employers and volunteers, case studies in organisations, and vital statistics.

Findings

The findings of the studies included in this special issue provide insights into the factors and mechanisms that hamper higher participation levels of older adults in paid employment and civil society, and give suggestions on how to improve their inclusion and how to deal with an ageing workforce.

Originality/value

Taken as a collective, the papers in this special issue help propel forward in significant ways the study of active ageing from an international and interdisciplinary perspective.