bluuebunny/crossref_metadata_2025 huggingface dataset:
Buoy perspective of a high‐resolution global ocean vector wind analysis constructed from passive radiometers and active scatterometers (1987–present)
Authors: Yu Lisan , Jin Xiangze
Published: October 2012

The study used 126 buoy time series as a benchmark to evaluate a satellite‐based daily, 0.25‐degree gridded global ocean surface vector wind analysis developed by the Objectively Analyzed airs‐sea Fluxes (OAFlux) project. The OAFlux winds were produced from synthesizing wind speed and direction retrievals from 12 sensors acquired during the satellite era from July 1987 onward. The 12 sensors included scatterometers (QuikSCAT and ASCAT), passive microwave radiometers (AMSRE, SSMI and SSMIS series), and the passive polarimetric microwave radiometer from WindSat. Accuracy and consistency of the OAFlux time series are the key issues examined here. A total of 168,836 daily buoy measurements were assembled from 126 buoys, including both active and archive sites deployed during 1988–2010. With 106 buoys from the tropical array network, the buoy winds are a good reference for wind speeds in low and mid‐range. The buoy comparison shows that OAFlux wind speed has a mean difference of −0.13 ms−1 and an RMS difference of 0.71 ms−1, and wind direction has a mean difference of −0.55 degree and an RMS difference of 17 degrees. Vector correlation of OAFlux and buoy winds is of 0.9 and higher over almost all the sites. Influence of surface currents on the OAFlux/buoy mean difference pattern is displayed in the tropical Pacific, with higher (lower) OAFlux wind speed in regions where wind and current have the opposite (same) sign. Improved representation of daily wind variability by the OAFlux synthesis is suggested, and a decadal signal in global wind speed is evident.
Observations on the characteristics of the exchange flow in the Dardanelles Strait
Authors: Jarosz Ewa , Teague William J. , Book Jeffrey W. , Beşiktepe Şükrü T.
Published: October 2012

A mooring section at each end of the Dardanelles Strait was deployed by the Naval Research Laboratory on 28–29 August 2008 and maintained until 11 October 2009. Each section was equipped with two bottom‐mounted Barny moorings and a vertical string that together delivered concurrent bottom pressure, temperature, salinity, and almost full‐water column current velocity observations. These observations at the mooring sections indicated that on longer timescales (monthly or longer), the exchange through the Dardanelles Strait showed little variability and had a two‐layer structure with brackish waters moving approximately southward in the upper layer and more saline Aegean waters flowing roughly northward underneath. On shorter time scales (synoptic), there were pronounced fluctuations in both layers. In the northern section, some manifested as almost simultaneous reversals of the flow direction in both layers with lighter upper‐layer waters backing into the Sea of Marmara and dense lower‐layer waters moving toward the Aegean Sea. In the southern section, some of the exchange variability consisted of a three‐layer flow structure with upper brackish and bottom salty layers moving toward the Aegean Sea and a middle salty layer flowing toward the Sea of Marmara. This three‐layer exchange persisted from a day to a week. Synoptic flow variability in the upper layer was partly related to both the along‐strait wind stress and the bottom pressure anomaly gradient, while lower‐layer current fluctuations were coherent with the bottom pressure anomaly gradient.
Mapping of the water ice content within the Martian surficial soil on the periphery of the retreating seasonal northern polar cap based on the TES and the OMEGA data
Authors: Kuzmin R. O. , Zabalueva E. V. , Evdokimova N. A. , Christensen P. R.
Published: October 2012

Analysis of seasonal data from the Mars Global Surveyor Thermal Emission Spectrometer (TES) shows a significant increase in thermal inertia during autumn, winter and spring in the middle and high latitudes of Mars. At each stage of the northern seasonal polar cap's recession in spring a distinct high thermal inertia (HTI) annulus arises around the cap's edge. Within this annulus, we estimated and mapped the springtime water ice content in the daily thermal skin depth layer using spring and summer values of the thermal inertia in TES surface footprints. The results show that the average water content in the surface soil within the HTI annulus varies from ∼5 vol % at the early stages of the seasonal polar cap retreating (Ls = 340°–360°) to ∼1 vol % at later stages (Ls = 60°–70°). Maximum values of water ice content within the HTI annulus occur at Ls = 0°–20° (2–6 vol %) and Ls = 20°–40° (4–10 vol %). We analyzed the temporal and spatial relationship between the HTI annuli and the water ice (WI) annuli at the edge of the northern seasonal polar cap. The water ice within the WI annuli was mapped using a water ice spectral index (the absorption band depth at the 1.5 μm wavelength) derived from the OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) imaging spectrometer aboard the Mars Express spacecraft. Recent OMEGA observations show that the WI annuli formation arises only around the retreating northern seasonal polar cap, never around the retreating southern seasonal cap. For this reason our study is confined only to the northern hemisphere. The observed relationship between the HTI and WI annuli in the northern hemisphere of Mars indicates a close physical interdependence between these two phenomena. Our results confirm that the seasonal permafrost exposed by the retreating northern polar cap (within the HTI annuli) is actively involved today in the condensation and sublimation processes in the modern water cycle on Mars. The water abundance in this annual condensation/sublimation cycle within the active layer may be an order of magnitude higher than all the annual water vapor abundance in the Martian atmosphere. Our results are consistent with existence of the positive mass balance of the northern permanent polar cap in the modern climatic period.
A subgrid channel model for simulating river hydraulics and floodplain inundation over large and data sparse areas
Authors: Neal Jeffrey , Schumann Guy , Bates Paul
Published: October 2012

This paper presents a new computationally efficient hydraulic model for simulating the spatially distributed dynamics of water surface elevation, wave speed, and inundation extent over large data sparse domains. The numerical scheme is based on an extension of the hydraulic model LISFLOOD‐FP to include a subgrid‐scale representation of channelized flows, which allows river channels with any width below that of the grid resolution to be simulated. The scheme is shown to be numerically stable and scalable, before being applied to an 800 km reach of the river Niger in Mali. The Niger application focused on the performance of four different model structures: a model without channels (two‐dimensional (2‐D) model), a model without a floodplain (one‐dimensional (1‐D) model), a model of the main channels and floodplain (1‐D/2‐D model), and the subgrid approach developed here. Inclusion of both the channel network and the floodplain was shown to be essential, meaning that large scale models of this region, including routing models for land surface schemes, will require a floodplain component. Including subgrid‐scale channels on the floodplain changed inundation dynamics over the delta significantly and increased simulation accuracy in terms of water level, wave propagation speed, and inundation extent. Furthermore, only the subgrid model showed a consistent parameterization when calibrated against either gauge or ICESat water level data, suggesting that connectivity provided by small channels is a strong control on the hydraulics of the floodplain, or, at the very least, that low resolution gridded hydraulic models require additional connectivity to represent the delta flow dynamics.
Reconstructing acoustic obstacles by planar and cylindrical waves
Authors: Li Jingzhi , Liu Hongyu , Sun Hongpeng , Zou Jun
Published: October 2012

In this paper, we develop a novel method of reconstructing acoustic obstacles in \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^2$\end{document}R2, which follows a similar spirit of the linear sampling method originated by Colton and Kirsch. The reconstruction scheme makes use of the near-field measurements encoded into the boundary Dirichlet-to-Neumann map or the Neumann-to-Dirichlet map. Both the plane waves and cylindrical waves are shown to meet the reconstruction purpose. Rigorous mathematical justification of the reconstruction scheme is established. The mapping properties of the newly introduced function operators involved in the reconstruction scheme are established. These results are of significant mathematical interests for their own sake. Moreover, due to the distinct properties of the function operators, the indictor function in the proposed reconstruction scheme exhibits completely different behaviors from those having been established for the indictor function in the original linear sampling method for inverse scattering problems. Numerical experiments are presented to illustrate the effectiveness of the proposed reconstruction scheme.
Liouville type theorems for nonlinear elliptic equations involving operator in divergence form
Authors: Hsini M.
Published: October 2012

The aim of this paper is to study the properties of the solutions of \documentclass[12pt]{minimal}\begin{document}${\rm div} (\mathcal {A}(x, \nabla u))\break +f_{1}(u)-f_{2}(u)=0$\end{document} div (A(x,∇u))+f1(u)−f2(u)=0 in all \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^{N}.$\end{document}RN. We obtain Liouville type boundedness for the solutions. We show that \documentclass[12pt]{minimal}\begin{document}$|u|\le (\frac{\alpha }{\beta })^{\frac{1}{m-q+1}}$\end{document}|u|≤(αβ)1m−q+1 on \documentclass[12pt]{minimal}\begin{document}$\mathbb {R}^{N},$\end{document}RN, under the assumptions f1(u) ⩽ αuq–1 and f2(u) ⩾ βum, for some 0 < α ⩽ β and m > q−1 > 0. If u does not change the sign, we prove that u is constant.
Epitaxial Pb(Zrx,Ti1−x)O3 (0.30 ≤ x ≤ 0.63) films on (100)MgO substrates for energy harvesting applications
Authors: Yeager Charles B. , Trolier-McKinstry Susan
Published: October 2012

Piezoelectric energy harvesting systems are of interest as a long-term power source for low-power wireless sensors. Transduction from elastic to electrical energy depends on the product of the piezoelectric charge and voltage coefficients; optimization of this figure of merit is an essential step towards improved microelectromechanical energy harvesting devices. This work reports on the composition dependence on the dielectric and piezoelectric properties of epitaxial {001}Pb(Zrx, Ti1−x)O3 films grown by chemical solution deposition and crystallized at 650 °C on (100)Pt//(100)MgO substrates for 0.63 ≤ x ≤ 0.30. The power generation figure of merit shows the greatest magnitude at compositions near x = 0.52, for which e31,f = −12 C/m2 and εr = 420. Lattice parameters were determined as a function of [Zr] to assess when comparisons to single domain properties calculated from Landau-Devonshire theory were appropriate. Furthermore, films doped with 1 at. % Mn had the highest observed figure of merit, four times greater than of AlN.
Vertical-cavity surface-emitting laser vapor sensor using swelling polymer reflection modulation
Authors: Ansbæk Thor , Nielsen Claus H. , Dohn Søren , Larsson David , Chung Il-Sug , Yvind Kresten
Published: October 2012

Vapor detection using a low-refractive index polymer for reflection modulation of the top mirror in a vertical-cavity surface-emitting laser (VCSEL) is demonstrated. The VCSEL sensor concept presents a simple method to detect the response of a sensor polymer in the presence of volatile organic compounds. We model the physics as a change in the top mirror loss caused by swelling of the polymer upon absorbing the target volatile organic compound. Further we show how acetone vapors at 82 000 ppm concentration can change the polymer coated VCSEL output power by 20 μW.
On left Hopf algebras within the framework of inhomogeneous quantum groups for particle algebras
Authors: Rodríguez-Romo Suemi
Published: October 2012

We deal with some matters needed to construct concrete left Hopf algebras for inhomogeneous quantum groups produced as noncommutative symmetries of fermionic and bosonic creation/annihilation operators. We find a map for the bidimensional fermionic case, produced as in Manin's [Quantum Groups and Non-commutative Hopf Geometry (CRM Univ. de Montréal, 1988)] seminal work, named preantipode that fulfills all the necessary requirements to be left but not right on the generators of the algebra. Due to the complexity and importance of the full task, we consider our result as an important step that will be extended in the near future.
Charge sensing in a Si/SiGe quantum dot with a radio frequency superconducting single-electron transistor
Authors: Yuan Mingyun , Yang Zhen , Savage D. E. , Lagally M. G. , Eriksson M. A. , Rimberg A. J.
Published: October 2012

We report the operation of a radio frequency superconducting single-electron transistor (rf-SSET) as a charge sensor for single and double Si/SiGe quantum dots (QDs). Real-time electron tunneling events are observed from the reflected signal of the rf-SSET with a charge sensitivity of 4×10−6 e/Hz, which demonstrates a fast charge detection time of a few tens of microseconds. Measurements of the reflected power are used to map out the stability diagram of the double quantum dot.
Electro-optic chirality control in MgO:PPLN
Authors: Shi Lei , Tian Linghao , Chen Xianfeng
Published: October 2012

The chirality of MgO-doped periodically poled lithium niobate (MgO:PPLN) by electro-optic effect was studied. It shows that optical propagation is reciprocal in MgO:PPLN under a transverse electric field and quasi-phase-matching condition, which bears similarity to natural optically active material like quartz. The specific rotation is shown to be proportional to the transverse electric field, making large polarization rotation in optically active material with small size possible. We also demonstrate that the chirality of MgO:PPLN can be controlled by the external electric field.
The spontaneous curvature of the water-hydrophobe interface
Authors: Sedlmeier Felix , Netz Roland R.
Published: October 2012

The temperature-dependent solvation of hydrophobic solutes in water is investigated by large-scale molecular dynamics simulations. A simultaneous fit of solvation free energies for spheres and cylinders with radii up to R = 2 nm yields a negative Tolman length on the order of 1 Å at room temperature, equivalent to a spontaneous curvature that favors water droplets over cavities. Pronounced crossover effects of the surface free energy are analyzed in terms of higher-order curvature corrections and water-discreteness effects.
Numerical study of an electrostatic plasma sheath containing two species of charged dust particles
Authors: Foroutan G. , Akhoundi A.
Published: October 2012

A multi-fluid model is used to study the dynamics of a dusty plasma sheath consists of electrons, ions, and two species of charged dust particles, i.e., nano-size and micron-size particles. It is found that, when the sheath is dominated by the nano-size dust grains, spatially periodic fluctuations are developed in the profiles of the sheath potential, and the number density and velocity of the plasma and dust particles. Due to inertial effects, the fluctuations in the parameters of the micron-size grains are much lower than those of the other parameters. The competition between the electric and ion drag forces plays the primary role in development of the fluctuations. The spatial period of the fluctuations is approximately a few Debye lengths and their amplitude depends on the plasma and dust parameters. The fluctuations are reduced by the increase in the radius, mass density, and Mach number of the nano-size particles, as well as the density and Mach number of the ions. But, they are enhanced by the increase in the plasma number density and the electron temperature. The sheath thickness demonstrates a non-monotonic behavior against variation of the nanoparticle parameters, i.e., it first decreases quickly, shows a minimum, and then increases. However, the sheath width always decreases with the plasma number density and ion Mach number, while grows linearly with the electron temperature.
Autonomous colloidal crystallization in a galvanic microreactor
Authors: Punckt Christian , Jan Linda , Jiang Peng , Frewen Thomas A. , Saville Dudley A. , Kevrekidis Ioannis G. , Aksay Ilhan A.
Published: October 2012

We report on a technique that utilizes an array of galvanic microreactors to guide the assembly of two-dimensional colloidal crystals with spatial and orientational order. Our system is comprised of an array of copper and gold electrodes in a coplanar arrangement, immersed in a dilute hydrochloric acid solution in which colloidal micro-spheres of polystyrene and silica are suspended. Under optimized conditions, two-dimensional colloidal crystals form at the anodic copper with patterns and crystal orientation governed by the electrode geometry. After the aggregation process, the colloidal particles are cemented to the substrate by co-deposition of reaction products. As we vary the electrode geometry, the dissolution rate of the copper electrodes is altered. This way, we control the colloidal motion as well as the degree of reaction product formation. We show that particle motion is governed by a combination of electrokinetic effects acting directly on the colloidal particles and bulk electrolyte flow generated at the copper-gold interface.
Fast off-lattice Monte Carlo simulations of soft-core spherocylinders: Isotropic-nematic transition and comparisons with virial expansion
Authors: Zong Jing , Zhang Xinghua , Wang Qiang
Published: October 2012

We proposed a novel anisotropic soft-core potential for spherocylinders that takes into account the degree of overlap between two spherocylinders, thus superior to other soft-core spherocylinder models depending only on the minimum distance between two line segments representing spherocylinders, for example, that used by Vink and Schilling [Phys. Rev. E 71, 051716 (2005)10.1103/PhysRevE.71.051716]. Using Monte Carlo simulations in an isothermal-isobaric ensemble with replica exchange at different pressures and multiple histogram re-weighting technique, we studied the isotropic-nematic transition of both models, which recover the standard model of hard spherocylinders for liquid crystals as the repulsion strength ε → ∞, and compared simulation results with virial expansion predictions. We found that isotropic-nematic transition still occurs at high enough densities even for small ε, and that virial expansion predictions become more accurate with increasing aspect ratio of spherocylinders and should be exact in the limit of infinitely large aspect ratio.
Energy free microwave based signal communication using ratchet effect
Authors: Kannan E. S. , Bisotto I. , Portal J.-C. , Beck T. J. , Jalabert L.
Published: October 2012

The ratchet based microwave detectors are implemented as receivers of amplitude, frequency, and pulse width modulated signals. The detector has a peak responsivity of 994 V/W and has excellent signal to noise ratio in the measurement bandwidth with its noise equivalent power of about 0.01 pico W/√Hz and 6.3 × 107 cm√Hz/W detectivity. The frequency limit of detection can be tuned by a suitable choice of the antidot parameters. The advantages of the utilizing ratchet based active antennas are simple circuitry, controllable spectral range, no power consumption, and natural rejection of stray electromagnetic radiations.
Bit error rate investigation of spin-transfer-switched magnetic tunnel junctions
Authors: Wang Zihui , Zhou Yuchen , Zhang Jing , Huai Yiming
Published: October 2012

A method is developed to enable a fast bit error rate (BER) characterization of spin-transfer-torque magnetic random access memory magnetic tunnel junction (MTJ) cells without integrating with complementary metal-oxide semiconductor circuit. By utilizing the reflected signal from the devices under test, the measurement setup allows a fast measurement of bit error rates at >106, writing events per second. It is further shown that this method provides a time domain capability to examine the MTJ resistance states during a switching event, which can assist write error analysis in great detail. BER of a set of spin-transfer-torque MTJ cells has been evaluated by using this method, and bit error free operation (down to 10−8) for optimized in-plane MTJ cells has been demonstrated.
A method of producing electrokinetic power through forward osmosis
Authors: Cherng Hon Kar , Zhao Cunlu , Yang Chun , Chay Low Seow
Published: October 2012

A power generation method for harvesting renewable energy from salinity gradient is proposed. The principle of the proposed method encompasses forward osmosis (FO) and electrokinetic phenomena. With the salinity difference between draw and feed solutions, FO allows spontaneous water flow across a semi-permeable membrane. The flow of water is then directed through a porous medium where the electric power is generated from the electrokinetic streaming potential. With a glass porous medium and a commercial flat sheet FO membrane in a batch mode configuration, our lab scale experimental system has demonstrated the produced electrokinetic voltages of about several hundreds of milli-volts.
Real-time measurement of picosecond THz pulses by an ultra-fast YBa2Cu3O7−d detection system
Authors: Thoma P. , Scheuring A. , Hofherr M. , Wünsch S. , Il'in K. , Smale N. , Judin V. , Hiller N. , Müller A.-S. , Semenov A. , Hübers H.-W. , Siegel M.
Published: October 2012

The temporal evolution of picosecond THz pulses generated at ANKA, the electron storage ring of the Karlsruhe Institute of Technology, has been measured in real-time using an ultra-fast YBa2Cu3O7−δ detection system. YBa2Cu3O7−δ thin-film detectors with 30 nm thickness were patterned to microbridges (2 μm long, 4.5 μm wide) and embedded into a planar log-spiral THz antenna. The detectors were glued on a silicon lens and installed in an ultra-fast readout system with a temporal resolution of 15 ps (full width at half maximum). Detector responses as short as 17 ps were recorded showing very good agreement with the expected storage ring bunch lengths.
Performance of p- and n-side illuminated microcrystalline silicon solar cells following 2 MeV electron bombardment
Authors: Smirnov V. , Astakhov O. , Carius R. , Pieters B. E. , Petrusenko Yu. , Borysenko V. , Finger F.
Published: October 2012

The impact of defects on the performance of p- and n-side illuminated microcrystalline silicon solar cells is investigated. The absorber layer spin density NS is controlled over some two orders of magnitude by electron bombardment and subsequent annealing steps. At increased NS (between 3 × 1016 and 1018 cm−3), performance of n-side illuminated cells is much more strongly reduced relative to p-side illuminated cells, particularly with regard to short circuit current density. Quantum efficiency measurements indicate a corresponding strong asymmetry in wavelength-dependence, which has been successfully reproduced by numerical device simulations.
The influence of radial heterostructuring on carrier dynamics in gallium nitride nanowires
Authors: Kar Ayan , Li Qiming , Upadhya Prashanth C. , Ah Seo Min , Wright Jeremy , Luk T. S. , Wang George T. , Prasankumar Rohit P.
Published: October 2012

Ultrafast optical pump-probe spectroscopy is used to study the influence of aluminum nitride (AlN) and aluminum gallium nitride (AlGaN) shells on carrier dynamics in radially heterostructured GaN nanowires (NWs). Our experiments reveal longer carrier relaxation times and lower lasing thresholds in NWs passivated with a higher bandgap shell, which can be attributed to a reduction in surface defect state density. We observe that carrier relaxation times vary with the nitride shell material and thickness, likely due to strain from the lattice mismatch between the core and shell materials. Our results demonstrate that radial heterostructuring is a promising route to controlling carrier dynamics in III-nitride NWs.
Ferromagnetic resonance of compensated ferromagnetic/antiferromagnetic bilayers
Authors: Dantas Ana L. , Oliveira L. L. , Silva M. L. , Carriço A. S.
Published: October 2012

We report a theoretical study of the ferromagnetic resonance (FMR) frequency Ω(H) of Fe/FeF2(110) and Fe/MnF2(110) uniaxial anisotropy compensated bilayers. We show that under external field perpendicular to the anisotropy axis, the uniform mode of the Fe-film becomes soft at an external field strength (H*=HAF−Hint⊥) smaller than the Fe anisotropy field. For strong interface exchange coupling, there is a gap in the FMR spectrum. In this case, Ω(H) is a monotonically increasing function of the external field strength and for any value of the external field strength Ω(H)>Ω(0). The value of the effective interface field downshifts (Hint⊥) and the value of Ω(0) may be used to estimate the interface exchange energy.
Plasmonic concentrator of magnetic field of light
Authors: Wróbel Piotr , Antosiewicz Tomasz J. , Stefaniuk Tomasz , Szoplik Tomasz
Published: October 2012

We propose an efficient concentrator of the magnetic component of evanescent field of light for measuring magnetic responses of nanostructures. It is in the form of a tapered fiber probe, which in its final part has corrugations along the angular dimension and is coated with metal except for the aperture at the tip. Internal, azimuthally polarized illumination is concentrated into a subwavelength spot with a strong longitudinal magnetic component Hz. Within the visual range of wavelengths 400–700 nm, the energy density of Hz is up to 50 times larger than that of the azimuthal electric Eϕ one. This dominant Hz contribution may be used for magnetic excitation of elementary cells of metamaterials with a single probe guiding a wide spectrum of generated plasmons.
The evolution of magnetic domain structure with magnetic history in amorphous film with perpendicular anisotropy
Authors: Gao Jinlong , Tang Shaolong , Li Yulong , Xia Wenbin , Tang Tao , Du Youwei
Published: October 2012

Amorphous rare-earth-Fe-B (RE-Fe-B) films were deposited on Si substrates at 300 °C by dc magnetron sputtering. The evolution of their magnetic domain structures with magnetic history was observed by magnetic force microscopy. It was found that the remanent domain configuration can be gradually transformed from stripes to bubbles after applying different magnetic fields along the out-of-plane direction, which indicates that the film has a perpendicular magnetic anisotropy. In addition, an in situ investigation on the evolution of domain structure under an in-plane field was carried out using a homemade sample holder. The results showed that the domain structure depends on both the applied field and the magnetic history. The present work provides a feasible approach for manipulating magnetic domains in amorphous RE-Fe-B film by employing a magnetic field.
Magnetization of 2.6 T in gadolinium thin films
Authors: Scheunert G. , Hendren W. R. , Ward C. , Bowman R. M.
Published: October 2012

There is renewed interest in rare-earth elements and gadolinium in particular for a range of studies in coupling physics and applications. However, it is still apparent that synthesis impacts understanding of the intrinsic magnetic properties of thin gadolinium films, particularly for thicknesses of topicality. We report studies on 50 nm thick nanogranular polycrystalline gadolinium thin films on SiO2 wafers that demonstrate single-crystal like behavior. The maximum in-plane saturation magnetization at 4 K was found to be 4πMS4 K = (2.61 ± 0.26) T with a coercivity of HC4 K = (160 ± 5) Oe. A maximum Curie point of TC = (293 ± 2) K was measured via zero-field-cooled–field-cooled magnetization measurements in close agreement with values reported in bulk single crystals. Our measurements revealed magnetic transitions at T1 = (12 ± 2) K (as deposited samples) and T2 = (22 ± 2) K (depositions on heated substrates) possibly arising from the interaction of paramagnetic face-centred cubic grains with their ferromagnetic hexagonal close-packed counterparts.
Carbon-doped Ge2Sb2Te5 phase change material: A candidate for high-density phase change memory application
Authors: Zhou Xilin , Wu Liangcai , Song Zhitang , Rao Feng , Zhu Min , Peng Cheng , Yao Dongning , Song Sannian , Liu Bo , Feng Songlin
Published: October 2012

Carbon-doped Ge2Sb2Te5 material is proposed for high-density phase-change memories. The carbon doping effects on electrical and structural properties of Ge2Sb2Te5 are studied by in situ resistance and x-ray diffraction measurements as well as optical spectroscopy. C atoms are found to significantly enhance the thermal stability of amorphous Ge2Sb2Te5 by increasing the degree of disorder of the amorphous phase. The reversible electrical switching capability of the phase-change memory cells is improved in terms of power consumption with carbon addition. The endurance of ∼2.1 × 104 cycles suggests that C-doped Ge2Sb2Te5 film will be a potential phase-change material for high-density storage application.
Doped polymer electrodes for high performance ferroelectric capacitors on plastic substrates
Authors: Khan M. A. , Bhansali Unnat S. , Zhang X. X. , Saleh Moussa M. , Odeh Ihab , Alshareef H. N.
Published: October 2012

Flexible ferroelectric capacitors with doped polymer electrodes have been fabricated on plastic substrates with performance as good as metal electrodes. The effect of doping on the morphology of polymer electrodes and its impact on device performance have been studied. Improved fatigue characteristics using doped and undoped poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) electrodes versus metal electrodes are observed. It is shown that the polymer electrodes follow classical ferroelectric and dielectric responses, including series resistance effects. The improved device characteristics obtained using highly conducting doped PEDOT:PSS suggest that it may be used both as an electrode and as global interconnect for all-polymer transparent circuits on flexible substrates.
Solar pond technology for large-scale heat processing in a Chilean mine
Authors: Garrido F. , Soto R. , Vergara J. , Walczak M. , Kanehl P. , Nel R. , García J.
Published: October 2012

Copper mining is the largest industrial activity in Northern Chile, a region that relies mostly on imported energy resources thus making the mining sector vulnerable to the rising cost of fuel oil and electricity. The extraction of copper is mostly accomplished by hydrometallurgy, a three-step low energy process consisting of heap leaching, concentration by solvent extraction, and metal recovery by electro-winning. Since the content of copper in its ore tends to degrade as the mining operation proceeds, higher leaching temperatures would be needed along with increasing energy requirements. In order to address this demand and considering that the region has one of the highest levels of solar radiation and clear skies, the authors assessed the solar pond technology for rising the temperature of the leaching stream. The working principle of such technology is presented, as well as its mathematical formulation, restrictions, and assumptions, aiming to simulate the performance of a solar pond and to size a suitable setup. The results indicate that this technology can provide sufficient heat to raise the temperature to a range of 50 to 70 °C throughout the year with an annual gross thermal supply of 626 GWh. In order to minimize the loss of water and salt from the pond, a closed salt cycle is suggested. Savings of up to 59 000 tons of diesel oil per year and the avoidance of 164 000 tons of CO2 per year could be achieved with a solar pond effective area of 1.43 km2 reaching an average efficiency of 19.4%. Thus, solar pond technology is suitable for attaining the goal of increasing the leaching temperature while diminishing fuel costs and greenhouse emissions.
Effects of fire regimes on herbaceous biomass and nutrient dynamics in the Brazilian savanna
Authors: Oliveras Immaculada , Meirelles Sergio T. , Hirakuri Valter L. , Freitas Cenira R. , Miranda Heloisa S. , Pivello Vânia R.
Published: October 2012

This study explores the long-term effects of fire treatments on biomass and nutrient pools in an open savanna from Central Brazil. Treatments included early, middle and late dry season burns every 2 years, a middle dry season burn every 4 years, and protection from fire on five 4-ha plots. We quantified aboveground biomass of graminoids and forbs/sub-shurbs, and their nutrient concentrations and stocks in both dry and wet seasons, and below-ground biomass down to 30-cm depth. We found strong differences between wet and dry season, with biomass and nutrient concentrations being highest in the wet season, across all fire treatments. Fire treatments had significant effects on plant nutrient stocks and root distribution, although total biomass was not affected. Concentrations of the most volatile nutrients (N, S, K and P) were higher in the herbaceous aboveground biomass of the quadrennial and the unburnt plots, suggesting that increases in fire frequency would reduce the amount of nutrients in aboveground biomass and increase the concentration of fine roots at the soil surface. Results highlight the role of fire in maintaining community dynamics in the Brazilian savanna. Overall, the quadrennial burn appears to be the optimal fire regime in open Cerrado vegetation.
Pixel and object-based classification approaches for mapping forest fuel types in Tenerife Island from ASTER data
Authors: Alonso-Benito Alfonso , Arroyo Lara A. , Arbelo Manuel , Hernández-Leal Pedro , González-Calvo Alejandro
Published: October 2012

Four classification algorithms have been assessed and compared with mapped forest fuel types from Terra-ASTER sensor images in a representative area of Tenerife Island (Canary Islands, Spain). A BEHAVE fuel-type map from 2002, together with field data also obtained in 2002 during the Third Spanish National Forest Inventory, was used as reference data. The BEHAVE fuel types of the reference dataset were first converted into the Fire Behaviour Fuel Types described by Scott and Burgan, taking into account the vegetation of the study area. Then, three pixel-based algorithms (Maximum Likelihood, Neural Network and Support Vector Machine) and an Object-Based Image Analysis were applied to classify the Scott and Burgan fire behaviour fuel types from an ASTER image from 3 March 2003. The performance of the algorithms tested was assessed and compared in terms of quantity disagreement and allocation disagreement. Within the pixel-based classifications, the best results were obtained from the Support Vector Machine algorithm, which showed an overall accuracy of 83%; 14% of disagreement was due to allocation and 3% to quantity disagreement. The Object-Based Image Analysis approach produced the most accurate maps, with an overall accuracy of 95%; 4% disagreement was due to allocation and 1% to quantity disagreement. The object-based classification achieved thus an overall accuracy of 12% above the best results obtained for the pixel-based algorithms tested. The incorporation of context information to the object-based classification allowed better identification of fuel types with similar spectral behaviour.
Estimating US federal wildland fire managers’ preferences toward competing strategic suppression objectives
Authors: Calkin David E. , Venn Tyron , Wibbenmeyer Matthew , Thompson Matthew P.
Published: October 2012

Wildfire management involves significant complexity and uncertainty, requiring simultaneous consideration of multiple, non-commensurate objectives. This paper investigates the tradeoffs fire managers are willing to make among these objectives using a choice experiment methodology that provides three key advancements relative to previous stated-preference studies directed at understanding fire manager preferences: (1) a more immediate relationship between the instrument employed in measuring preferences and current management practices and operational decision-support systems; (2) an explicit exploration of how sociopolitical expectations may influence decision-making and (3) consideration of fire managers’ relative prioritisation of cost-containment objectives. Results indicate that in the current management environment, choices among potential suppression strategies are driven largely by consideration of risk to homes and high-value watersheds and potential fire duration, and are relatively insensitive to increases in cost and personnel exposure. Indeed, when asked to choose the strategy they would expect to choose under current social and political constraints, managers favoured higher-cost suppression strategies, ceteris paribus. However, managers indicated they would personally prefer to pursue strategies that were more cost-conscious and proportionate with values at risk. These results confirm earlier studies that highlight the challenges managerial incentives and sociopolitical pressures create in achieving cost-containment objectives.
Exotic annual grass invasion alters fuel amounts, continuity and moisture content
Authors: Davies Kirk W. , Nafus Aleta M.
Published: October 2012

Many exotic annual grasses are believed to increase wildfire frequency to the detriment of native vegetation by increasing fine fuels and thus, creating a grass-fire cycle. However, information on differences in fuel characteristics between invaded and non-invaded plant communities is lacking, or is based mainly on speculation and anecdotal evidence. We compared fuel biomass, cover, continuity and moisture content in plant communities invaded and not invaded by cheatgrass (Bromus tectorum L.), an exotic annual grass, in 2010 and 2011 in south-eastern Oregon, USA. Annual grass-invaded communities had higher fine fuel amounts, greater fuel continuity, smaller fuel gaps and lower fuel moisture content than did non-invaded plant communities. These conditions would increase the probability that ignition sources would contact combustible fuels and that fires would propagate. Fuel characteristics in the annual grass-invaded communities in our study may also support faster spreading fires. Fuel moisture content was low enough to burn readily more than a month earlier in annual grass-invaded communities than in non-invaded communities, thereby expanding the wildfire season. The cumulative effect of these differences in fuel characteristics between exotic annual grass-invaded and non-invaded plant communities is an increased potential for frequent, large-scale, fast-spreading wildfires. We suggest that research is needed to develop methods to mediate and reverse these changes in fuel characteristics associated with B. tectorum invasion.
Assessing the flammability of surface fuels beneath ornamental vegetation in wildland–urban interfaces in Provence (south-eastern France)
Authors: Ganteaume Anne , Jappiot Marielle , Lampin Corinne
Published: October 2012

The objectives of this paper are to assess in laboratory conditions the flammability of undisturbed litter sampled beneath plants of seven species that are among those most frequently planted in hedges in Provence (south-eastern France). The variability in litter flammability recorded during burning experiments was partly explained by the proportions of the different litter components of each species. Phyllostachys sp. and Nerium oleander litters were the quickest to ignite whereas Prunus laurocerasus litter had the lowest bulk density and long time-to-ignition, but high flame-propagation. Photinia fraseri litter ignited frequently and had a high flame spread whereas Pittosporum tobira litter ignited the least frequently and for the shortest duration. Cupressus sempervirens litter had the highest bulk density and the longest flaming duration but the lowest flame propagation. Pyracantha coccinea litter was the slowest to ignite and flame propagation was low but lasted a long time. Co-inertia analysis identified species with the same flammability characteristics according to the composition of their litter. Hierarchical cluster analysis ranked the seven species in four distinct clusters from the most flammable (Photinia fraseri and Prunus laurocerasus) to the least flammable (Pittosporum tobira), the other species displaying two groups of intermediate flammability. These latter species should not be used in hedges planted in wildland–urban interfaces in south-eastern France.
Critical role for lysyl oxidase in mesenchymal stem cell-driven breast cancer malignancy
Authors: El-Haibi Christelle P. , Bell George W. , Zhang Jiangwen , Collmann Anthony Y. , Wood David , Scherber Cally M. , Csizmadia Eva , Mariani Odette , Zhu Cuihua , Campagne Antoine , Toner Mehmet , Bhatia Sangeeta N. , Irimia Daniel , Vincent-Salomon Anne , Karnoub Antoine E.
Published: October 2012

Mesenchymal stem cells (MSCs) are multipotent progenitor cells with the ability to differentiate into multiple mesoderm lineages in the course of normal tissue homeostasis or during injury. We have previously shown that MSCs migrate to sites of tumorigenesis, where they become activated by cancer cells to promote metastasis. However, the molecular and phenotypic attributes of the MSC-induced metastatic state of the cancer cells remained undetermined. Here, we show that bone marrow-derived human MSCs promote de novo production of lysyl oxidase (LOX) from human breast carcinoma cells, which is sufficient to enhance the metastasis of otherwise weakly metastatic cancer cells to the lungs and bones. We also show that LOX is an essential component of the CD44-Twist signaling axis, in which extracellular hyaluronan causes nuclear translocation of CD44 in the cancer cells, thus triggering LOX transcription by associating with its promoter. Processed and enzymatically active LOX, in turn, stimulates Twist transcription, which mediates the MSC-triggered epithelial-to-mesenchymal transition (EMT) of carcinoma cells. Surprisingly, although induction of EMT in breast cancer cells has been tightly associated with the generation of cancer stem cells, we find that LOX, despite being critical for EMT, does not contribute to the ability of MSCs to promote the formation of cancer stem cells in the carcinoma cell populations. Collectively, our studies highlight a critical role for LOX in cancer metastasis and indicate that the signaling pathways controlling stroma-induced EMT are distinct from pathways regulating the development of cancer stem cells.
On the concept of syntactic function in a functional grammar
Authors: Cidrás Escáneo Francisco A.
Published: October 2012

The study takes a critical look at the status of syntactic functions within a multi-level view of grammatical relations. Re-examining the widespread approach to the traditional notion of ‘syntactic function’ that treats it as fitting into a system of syntactic, semantic and pragmatic functions, the syntactic functions are seen to be cognitively invisible vis-à-vis the other two, and this is assumed to be more than an irrelevant accident. After a brief review of theoretical treatments of syntactic functions within functionalism, the conclusion is reached that, contrary to what is commonly assumed, e.g. in FG or SFG, unlike functions on the other two levels, syntactic functions per se contribute nothing to sentence meaning, and thus should no longer be considered functions. Instead, this study treats them as syntactic figures, i.e. instrumental, multi-purpose, formal devices whose job it is to give optimal expression to functional content which may be of just two types: either semantic or pragmatic.
Habitus, field and discourse
Authors: Inghilleri Moira
Published: October 2012

Taking Toury’s model of norms as its starting point, this paper examines the macro–micro relationship evident within the context and culture of interpreting activity. The paper theorises this relationship drawing on Bourdieu’s concepts of habitus and field and Bernstein’s theory of pedagogic discourse. It proposes a model which directs the analysis of norms to the social dimension of language and cognition, as well as to the sociological and ideological determinants of what counts as a legitimate meaning in a particular context. The paper draws on the analysis of a particular context—the interpreted political asylum interview. However, it suggests the possibility of applying a similar theoretical model across a range of interpreting contexts.
Conversion in English computer terminology
Authors: Belda Medina José R.
Published: October 2012

Computer terminology has recently become very influential in languages other than English. One of the major problems affecting Spanish translation in this field derives from the high flexibility of English towards conversion, the process whereby a term belonging to a specific grammatical category can be used with different syntactic functions without requiring change in its form. Although no agreement exists on the definition and extent of conversion, this process poses some important problems for the Spanish translation. This paper intends to analyze and classify the most important types of conversion in English computer terminology and describe the major problems affecting the Spanish translation.
Tone of voice guides word learning in informative referential contexts
Authors: Reinisch Eva , Jesse Alexandra , Nygaard Lynne C.
Published: October 2012

Listeners infer which object in a visual scene a speaker refers to from the systematic variation of the speaker's tone of voice (ToV). We examined whether ToV also guides word learning. During exposure, participants heard novel adjectives (e.g., “daxen”) spoken with a ToV representing hot, cold, strong, weak, big, or small while viewing picture pairs representing the meaning of the adjective and its antonym (e.g., elephant–ant for big–small). Eye fixations were recorded to monitor referent detection and learning. During test, participants heard the adjectives spoken with a neutral ToV, while selecting referents from familiar and unfamiliar picture pairs. Participants were able to learn the adjectives' meanings, and, even in the absence of informative ToV, generalize them to new referents. A second experiment addressed whether ToV provides sufficient information to infer the adjectival meaning or needs to operate within a referential context providing information about the relevant semantic dimension. Participants who saw printed versions of the novel words during exposure performed at chance during test. ToV, in conjunction with the referential context, thus serves as a cue to word meaning. ToV establishes relations between labels and referents for listeners to exploit in word learning.