bluuebunny/crossref_metadata_2025 huggingface dataset:
Revised crustal architecture of the southeastern Carpathian foreland from active and passive seismic data
Authors: Enciu Dana M. , Knapp Camelia C. , Knapp James H.
Published: August 2009

Integration of active and passive source seismic data is employed in order to study the nature of the relationships between crustal seismicity and geologic structures in the southeastern (SE) Carpathian foreland of Romania and the possible connection with the Vrancea Seismogenic Zone (VSZ) of intermediate‐depth seismicity, one of the most active earthquake‐prone areas in Europe. Crustal epicenters and focal mechanisms are correlated with four deep industry seismic profiles, the reprocessed Danube and Carpathian Integrated Action on Process in the Lithosphere and Neotectonics (DACIA PLAN) profile and the Deep Reflection Acquisition Constraining Unusual Lithospheric Activity II and III (DRACULA) profiles in order to understand the link between neotectonic foreland deformation and Vrancea mantle seismicity. Projection of crustal foreland hypocenters onto deep seismic profiles identifies several active crustal faults in the SE Carpathian foreland and suggests a mechanical coupling between the mantle located VSZ and the overlying foreland crust. The coupled associated deformation appears to take place on the Trotus Fault, the Sinaia Fault, and the newly detected Ialomita Fault. Seismic reflection imaging reveals the absence of west dipping reflectors in the crystalline crust and a slightly east dipping to horizontal Moho in the proximity of the Vrancea area. These findings argue against previously purported mechanisms to generate mantle seismicity in the VSZ including oceanic lithosphere subduction in place and oceanic slab break off, furthermore suggesting that the Vrancea seismogenic body is undetached from the overlying crust in the foreland.
Very high resolution precipitation climatologies from the Tropical Rainfall Measuring Mission precipitation radar
Authors: Nesbitt Stephen W. , Anders Alison M.
Published: August 2009

To investigate processes related to the interaction of topography and precipitation, a tropics‐wide (±36° latitude) high resolution (0.1°) ten year (1998–2007) rainfall climatology is presented from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) using algorithm 2A25 version 6 near‐surface rain. We observe a tight coupling between precipitation and topography with distinct precipitation‐topography relationships present in northwest South America and South Asia. An error model is developed by subsampling the TRMM Multi‐satellite Precipitation Analysis as sampled by the PR. The error model predicts observed sampling error as a function of resolution, rain rate and sampling frequency with an r2 of 0.82. This error model indicates that the precipitation climatology at 0.1° resolution does resolve precipitation gradients in regions with large average daily rain totals including the Andes, Western Ghats, and Himalaya.
Ocean tides heat Enceladus
Authors: Tyler R. H.
Published: August 2009

With a young, highly reflective surface and vigorous geological activity, Saturn's tiny moon Enceladus has been one of the most mysterious planetary bodies in the solar system. Recent observations from the Cassini spacecraft show vast plumes of vapor erupting from geysers near the south pole, and inferred heat fluxes of about 100 mW/m2 for the same region have helped consolidate the essential enigma of Enceladus: there must be a relatively large and unidentified source of heat in the tiny moon. Here we present a case for heating from dissipation by tidal flow in an ice‐covered ocean. We show that if the spin axis of Enceladus is tilted with respect to its orbital plane by at least 0.05 degree then strong tidal flow will be generated with enough dissipative heating to explain the observed heat flux. In an alternative case of a shallow (10 km or less) ocean, comparable flow velocities and heating may be obtained by eccentricity tidal forces.
Air‐sea gas exchange of CO2 and DMS in the North Atlantic by eddy covariance
Authors: Miller Scott , Marandino Christa , de Bruyn Warren , Saltzman Eric S.
Published: August 2009

We report the first simultaneous eddy covariance flux measurements of CO2 and dimethylsulfide (DMS) over the open ocean for two North Atlantic cruises. After normalization for Schmidt number, the two gases give essentially identical gas transfer coefficients and wind speed dependences for the wind speed range 2–10 ms−1. The data indicate a linear relationship between the gas transfer coefficient and mean wind speed, with measured gas transfer coefficients slightly above the Wanninkhof (1992) parameterization, particularly at low wind speeds.
Temporal trend in anthropogenic sulfur aerosol transport from central and eastern Europe to Israel
Authors: Karnieli Arnon , Derimian Yevgeny , Indoitu Rodica , Panov Natalya , Levy Robert C. , Remer Lorraine A. , Maenhaut Willy , Holben Brent N.
Published: August 2009

Decrease of sulfur emissions in central and eastern Europe over the past 3 decades is well documented and linked to changes in economic activity, use of different fuels, addition of pollution controls, etc. These changes result in a decreasing trend of sulfate aerosol and aerosol forcing over the source region, but also at a receptor site located in southern Israel, thousands of kilometers downwind of the original source. A combination of several independent observations, namely, satellite and ground‐based remote sensing, in situ aerosol sampling, and backward trajectory analysis, was implemented to show significant downward trends in fine particle aerosol optical thickness (AOT), in general, and sulfur aerosol, in particular, between 1995 and 2007. For the study years, MODIS‐Terra observations over central and eastern Europe show 38% reduction of fine AOT. At the reception site in southern Israel, 43% reduction of fine AOT was observed by a ground‐based sun/sky photometer and 25% reduction of sampled fine aerosols was obtained. During the corresponding observation periods, the coarse mode AOT has remained constant. The majority of the backward trajectories, where meaningful sulfur events were observed at the receptor site, are originated from eastern and central Europe. The aerosol radiative effect at top of the atmosphere has become less negative during the past decade, decreasing by 30% in Europe and 67% in Israel. The decrease in negative cloud‐free aerosol forcing is consistent with observations of “global brightening” reported since 1990.
Long‐term observations of carbonaceous aerosols in the Austral Ocean atmosphere: Evidence of a biogenic marine organic source
Authors: Sciare J. , Favez O. , Sarda‐Estève R. , Oikonomou K. , Cachier H. , Kazan V.
Published: August 2009

Long‐term observations of carbonaceous aerosols in the Austral Ocean are reported here for the first time from almost 5 years of continuous filter sampling performed at Amsterdam Island (37°48′S, 77°34′E). Black carbon concentrations determined by optical method were among the lowest reported for marine atmosphere, with monthly mean levels ranging from 2–5 ng C/m3 during summer to 7–13 ng C/m3 during winter. A clear seasonal pattern was also observed for organic aerosols, but in opposite phase, with maximum values during the austral summer period (>250 ng C/m3) and minimum concentrations (100 ng C/m3) during winter. This seasonal variation of organic concentration was found to be almost entirely related to the water‐insoluble organic carbon fraction, suggesting a primary origin for these organics, most probably through bubble bursting processes. Moreover, this summer maximum observed for organic aerosols was found to be correlated with satellite‐derived chlorophyll a concentrations averaged over an oceanic region upwind of the sampling site and characterized by relatively high biogenic activity. This oceanic region being located at 1000–2000 km far away from the monitoring station, atmospheric ageing may have played a significant role on the levels and size‐resolved properties of marine organics collected at Amsterdam Island. This biogenic marine organic source of primary origin in the Austral Ocean is fully consistent with similar observations previously reported for the Northern Atlantic Ocean and brings further evidences of the major role of marine organic emissions over remote oceanic regions.
The position and function of the Notch‐mediated eye growth organizer: the roles of JAK/STAT and four‐jointed
Authors: Gutierrez‐Aviño Francisco Jose , Ferres‐Marco Dolors , Dominguez Maria
Published: August 2009

In many animal systems, the local activation of patterning signals in spatially confined regions (organizers) is crucial for promoting the growth of developing organs. Nevertheless, how organizers are set up and how their activity influences global organ growth remains poorly understood. In the Drosophila eye, local Notch activation establishes a conserved dorsal–ventral organizer that promotes growth. The dorsal selector Iroquois complex defines the position of the organizer at the mid‐first instar, and through its ligand, unpaired, the Janus kinase (JAK)/signal transducers and activator of transcription (STAT) pathway is thought to mediate global growth downstream of the organizer. However, here we show that the unpaired/JAK/STAT pathway is actually a fundamental element in the spatial control of the organizer, upstream from Notch activation. Furthermore, we identify four‐jointed, a target of the Fat and Hippo tumour‐suppressor pathways, as a mediator of the growth controlled by the organizer. These findings redefine the process of organizer formation and function, and they identify four‐jointed as a regulatory node, integrating multiple growth‐control pathways.
A Perspective on Improving Evidence and Practice in Cluttering
Authors: Scott Kathleen Scaler , St. Louis Kenneth O.
Published: August 2009

In the past, the rationale for cluttering to be ignored, not to be taken seriously, and not to be diagnosed could be attributed to several factors stemming from problems in definition and research design. This article reviews these factors and outlines advances being made in the state of evidence on cluttering. Recommendations for ensuring that cluttering research, diagnosis, and treatment remain based in evidence are discussed.
Cluttering in the Communicative Disorders Curriculum
Authors: Tetnowski John A.
Published: August 2009

Cluttering is discussed openly in the fluency literature, but few educational opportunities for learning more about cluttering exist in higher education. The purpose of this manuscript is to explain how a seminar in cluttering was developed for a group of communication disorders doctoral students. The major theoretical issues, educational questions, and conclusions are discussed.
“Cluttered” Parenting
Authors: Adams Charley
Published: August 2009

This article is designed to call attention to the experiences of being a parent of a child who clutters. Three parents were interviewed. Although their stories are very different, they share similar challenges. Difficulties include struggling to understand a child who clutters, obtaining an initial diagnosis of cluttering, finding a speech-language pathologist with the knowledge and skills to work with a child who clutters, and helping a child with cluttering learn how to socialize with his/her peers.
Global Landscape of Cluttering
Authors: Reichel Isabella K. , Bakker Klaas
Published: August 2009

The global emphasis of the International Cluttering Association (ICA) is manifested in multiple dimensions. This article focuses on two of them, namely, resources available through the ICA Web site and the results of an International Cluttering Survey (ICS), which had been presented to 25 members of the Committee of the International Representatives of the ICA. The answers of the representatives to questions regarding awareness of cluttering, definitions, professional preparation, goals for education about cluttering and approaches for achieving goals, are compared and analyzed.
Thermoelectric properties of Ba3Co2O6(CO3)0.7 containing one-dimensional CoO6 octahedral columns
Authors: Iwasaki Kouta , Yamamoto Teruhisa , Yamane Hisanori , Takeda Takashi , Arai Shigeo , Miyazaki Hidetoshi , Tatsumi Kazuyoshi , Yoshino Masahito , Ito Tsuyoshi , Arita Yuji , Muto Shunsuke , Nagasaki Takanori , Matsui Tsuneo
Published: August 2009

The thermoelectric properties of Ba3Co2O6(CO3)0.7 have been investigated using prismatic single crystals elongated along the c axis. Ba3Co2O6(CO3)0.7 has a pseudo-one-dimensional structure similar to that of 2H perovskite-type BaCoO3 and contains CoO6 octahedral columns running parallel to the c axis. The prismatic crystals are grown by a flux method using a K2CO3–BaCl2 flux. The electrical conductivity (σ) along the columns (c axis) exhibits a metallic behavior (670–320 S cm−1 in the temperature range of 300–1100 K), whereas the temperature dependence of the electrical conductivity perpendicular to the c axis is semiconducting. The Seebeck coefficient (S) along the columns is positive and greater than 100 μV K−1 over the measured temperature range (116–128 μV K−1). Ba3Co2O6(CO3)0.7 shows power factors (σS2) of 5.5×10−4–9.0×10−4 W m−1 K−2 above room temperature, relatively high values for an oxide material.
Charged particle-display
Authors: Cho Sung Nae
Published: August 2009

An optical shutter based on charged particles is presented. The output light intensity of the proposed device has an intrinsic dependence on the interparticle spacing between charged particles, which can be controlled by varying voltages applied to the control electrodes. The interparticle spacing between charged particles can be varied continuously and this opens up the possibility of particle based displays with continuous grayscale.
Nonlinear frequency-mixing photoacoustic imaging of a crack
Authors: Chigarev N. , Zakrzewski J. , Tournat V. , Gusev V.
Published: August 2009

We present a technique for nonlinear photoacoustic imaging of cracks by laser excitation with intensity modulation at two fundamental frequencies combined with detection at mixed frequencies. By exploiting the strong dependence of the photoacoustic emission efficiency on the state—open or closed—of the contacts between the crack faces, remarkably enhanced image contrast is observed, ∼20 times higher than in linear photoacoustic images at the highest of the fundamental frequencies.
Photonic bands in two-dimensional metallodielectric photonic crystals composed of metal coated cylinders
Authors: Cheng Chuan , Xu Can
Published: August 2009

Photonic bands in two-dimensional metallodielectric (MD) periodic systems composed of metal coated cylinders are investigated theoretically based on frequency dependent plane-wave expansion method. For the case of E-polarization, although the thickness of metal coating is less than half of the cylinder’s radius, most of MD photonic bands are the same as photonic bands composed of pure metal cylinders. This property provides us with a way to substitute metal photonic crystals with MD photonic crystals in many applications. In addition, flatbands are discovered in MD photonic band structures, which can be tuned by changing the thickness of metal coating while other photonic bands do not change their positions. For the case of H-polarization, the lowest frequency band gap (between the first and the second bands) can open up when the thickness of metal coating is thick enough. According to approximate calculation based on Maxwell–Garnett type effective medium theory and comparison with recent studies on three-dimensional MD photonic band structures, we predict that the lowest frequency band gap is not because of Bragg scattering but result from the individual metal coated dielectric cylinders, so that the gap is independent on geometry of photonic crystal lattices. Then, numerical calculation validates that our prediction is right.
Demonstration of microcantilever array with simultaneous readout using an in-plane photonic transduction method
Authors: Hu Weisheng , Anderson Ryan , Qian Yusheng , Song Jigou , Noh Jong Wook , Kim Seunghyun , Nordin Gregory P.
Published: August 2009

We demonstrate a microcantilever array with an in-plane photonic transduction method for simultaneous readout of each microcantilever. The array is fabricated on a silicon-on-insulator substrate. Rib waveguides in conjunction with a compact waveguide splitter network comprised of trench-based splitters and trench-based bends route light from a single optical input to each microcantilever on the chip. Light propagates down a rib waveguide integrated into the microcantilever and, at the free end of the microcantilever, crosses a small gap. Light is captured in static asymmetric multimode waveguides that terminate in Y-branches, the outputs of which are imaged onto an InGaAs line scan camera. A differential signal for each microcantilever is simultaneously formed from the two outputs of the corresponding Y-branch. We demonstrate that reasonable signal uniformity is obtained with a scaled differential signal for seven out of nine surviving microcantilevers in an array.
A fast, direct x-ray detection charge-coupled device
Authors: Denes P. , Doering D. , Padmore H. A. , Walder J.-P. , Weizeorick J.
Published: August 2009

A charge-coupled device (CCD) capable of 200 Mpixels/s readout has been designed and fabricated on thick, high-resistivity silicon. The CCDs, up to 600 μm thick, are fully depleted, ensuring good infrared to x-ray detection efficiency, together with a small point spread function. High readout speed, with good analog performance, is obtained by the use of a large number of parallel output ports. A set of companion 16-channel custom readout integrated circuits, capable of 15 bits of dynamic range, is used to read out the CCD. A gate array-controlled back end data acquisition system frames and transfers images, as well as provides the CCD clocks.
First-principles study of the electronic, optical, and lattice dynamics properties of LiInSe2 polymorph
Authors: Li Yanlu , Fan Weiliu , Sun Honggang , Cheng Xiufeng , Li Pan , Zhao Xian
Published: August 2009

First-principles calculations of the electronic, optical, and lattice dynamics properties of LiInSe2 polymorph were performed with the density functional theory plane-wave pseudopotential method. The results of electronic structure reveal that the different coordinated structure for α-NaFeO2-type LiInSe2 leads to the broadening of density of states and the smaller band gap. Various optical properties, including the dielectric function, reflectivity, absorption coefficient, refractive index, and the energy-loss spectrum as functions of the photon energy were calculated and are found to be in good agreement with experiments. We also presented phonon dispersion relation, zone-center optical mode frequency, density of phonon states, and some thermodynamic properties, such as constant volume heat capacity and Debye temperature. The results show that the α-NaFeO2-type LiInSe2 does not only have special optical properties but also demonstrates special vibrational properties and thermodynamic properties, which may lead to significance research meaning and application value.
Temperature dependence of the optical transitions in Ga0.64In0.36N0.046As0.954 multiquantum wells of various widths studied by photoreflectance
Authors: Kudrawiec R. , Poloczek P. , Misiewicz J. , Ishikawa F. , Trampert A. , Ploog K. H.
Published: August 2009

The temperature dependencies of optical transitions in as-grown Ga0.64In0.36N0.046As0.954 multiple quantum wells (QWs) of various widths (ranging from 3.9 to 8.1 nm) grown at the low temperature of 375 °C were studied by photoreflectance (PR). In addition to the 11H transition, which is the fundamental transition for this QW, the optical transitions between excited states (22H and 33H transitions, where the notation klH denotes the transition between the kth heavy-hole valence subband and the lth conduction subband) were clearly observed in the PR spectra. The temperature dependencies of the QW transition energies were analyzed using Varshni and Bose–Einstein expressions. It was found that with increasing temperature, both the ground-state and the excited-state transitions shift to the red without showing S-shape-type behaviors, which are typical for photoluminescence from this system. This shift does not depend on the QW width and amounts to ∼80 meV for the 11H transition and ∼100 meV for the 22H and 33H transitions in the temperature range of 10–300 K. These shifts are comparable to those of N-free QWs.
Measurement and calculation of surface tension for undercooled liquid nickel and its alloy
Authors: Wang H. P. , Chang J. , Wei B.
Published: August 2009

The surface tensions of metastable undercooled liquid nickel and its alloy are experimentally measured and theoretically calculated by electromagnetic levitation oscillating droplet method and molecular dynamics method, respectively. The experimental undercoolings for liquid Ni and Ni90.1Si9.9 alloy are 201 and 206 K, whereas the calculated undercoolings are up to 426 and 323 K. The measured surface tension displays the same undercooling dependence as the molecular dynamics calculation. The surface tension increases linearly with the increase in undercooling and no break occurs at the melting temperature. It is found that the correlation of surface tension with temperature predicted by molecular dynamics calculation agrees with the experimental results for both pure Ni and its alloy.
Maximal violation of Bell’s inequalities and Pauli spin matrices
Authors: Bohata Martin , Hamhalter Jan
Published: August 2009

The paper deals with the structure of Bell’s inequalities (Clauser, Horne, Shimony, and Holt (CHSH) form). It is established that 2 is the universal bound for Bell’s correlations given by a general correlation duality on a complex linear space. Using geometric arguments the maximal violation of Bell’s inequalities is described on this abstract level. It is proved that Bell’s inequalities are maximally violated for general ∗-algebras and a faithful state exactly when the corresponding elements are the Pauli spin matrices. Interesting structural consequences of this result are derived. They demonstrate that the maximal violation requires a very “nonclassical” position of the local systems. Moreover, the maximal strength of Bell’s correlations for a general state with respect to nearly commuting subalgebras is characterized in terms of the spin systems and tracial properties of the local states.
Combinatorial (Ba,Sr)TiO3 thin film growth: X-ray diffraction and Raman spectroscopy
Authors: Bouyanfif H. , Wolfman J. , El Marssi M. , Yuzyuk Y. , Bodeux R. , Gervais M. , Gervais F.
Published: August 2009

We report the investigation of the (Ba,Sr)TiO3 (BST) system of technological importance for microwave applications. The development of the combinatorial method enabled us to grow and study a library of samples ranging from BaTiO3 to SrTiO3 (ST) deposited on MgO substrate. The spatial control of the stoichiometry and of the structure has been evidenced and probed using energy dispersive x-ray spectroscopy, high resolution x-ray diffraction, and Raman spectroscopy. A global and coherent picture emerged from the complex interplay between the epitaxial/thermal stress and stoichiometry changes. Taking into account elastic interactions with the substrate we present subtle symmetry changes in the BST library in comparison with the bulk phase diagram such as tetragonal distortion observed on the ST side. Finally underdamped soft mode hardening and polar modes are detected on the high barium and strontium compositions, respectively, highlighting fundamental dynamical/structural differences with their bulk counterparts.
Constitutive theory of anisotropic rigid heat conductors
Authors: Liu I-Shih
Published: August 2009

For rigid heat conductors, the constitutive equation of the heat flux is usually assumed to be independent of the deformation of the body, or equivalently by setting the deformation gradient as the identity tensor in the constitutive equations. However, the notion of material symmetry would have involved change in reference configurations, hence also change in deformation gradients. Consequently it would be impossible to consider anisotropic rigid heat conductors from such a formulation. In this paper, rigid heat conductors are treated with rigidity as internal constraint and a constitutive theory consistent with the principle of material frame indifference, material symmetry, and entropy principle is presented. Constitutive restrictions for a transversely isotropic rigid heat conductor are carefully analyzed.
Surface-plasmon-enhanced photoluminescence from metal-capped Alq3 thin Films
Authors: Tam Man Chun , Su Huimin , Wong Kam Sing , Zhu Xiuling , Kwok Hoi Sing
Published: August 2009

Absolute quantum efficiencies of surface-plasmon-enhanced photoluminescence from Au capped Alq3 films were measured using an integrating sphere. The metal “mirror” and directional enhancement effects due to surface roughness which usually occur in forward/backward collection measurements were eliminated using this integrating sphere technique. Up to 40% of the enhanced photoluminescence observed using the forward/backward collection method was shown to have come from mirror and/or enhanced directional scattering effects. Purcell factors obtained from the integrating sphere data and from time-resolved photoluminescence measurements were consistent, confirming surface-plasmon coupling. Incorporating a thin spacer layer enhanced the quantum efficiency and also eliminated nonradiative recombination due to the metal layer. The results clearly show the importance of using an integrating sphere when measuring overall surface-plasmon quantum efficiencies to eliminate directional scattering effects.
Origin of giant polarization splitting in high quality organic microcavities
Authors: Stelitano S. , Savasta S. , Patané S. , De Luca G. , Monsù Scolaro L.
Published: August 2009

We study the emission properties of a high quality monolithic microcavity with an embedded ultrathin organic tetrakis(4-methoxyphenyl)porphyrin layer. Spectral and angle-resolved photoluminescence measurements show a well defined polarized doublet at detection angles larger than 15°. The splitting energy ranges up to 70 meV. The usual employed mechanism, based on the mismatch between the center of the mirror stop band and the wavelength of the microcavity, accounts only for a small fraction of the observed splitting. A transfer matrix model taking into account the optical anisotropy of the organic layer, has been employed to reproduce the observed experimental results. The anisotropy of the organic layer, confirmed by optical absorption spectroscopy, origins from a local molecular order as inferred by atomic force microscopy measurements.
Photoluminescence properties of Eu2+-activated CaSi2O2N2: Redshift and concentration quenching
Authors: Song Xiufeng , Fu Renli , Agathopoulos Simeon , He Hong , Zhao Xinran , Zhang Shaodong
Published: August 2009

Highly efficient CaSi2O2N2:Eu2+ green phosphors were synthesized via solid-state reaction method. The produced phosphors are effectively excited with UV-vis light of wavelength between 300 and 460 nm and emit a single, intense, and broad emission band centered at 538 nm. The experimental results and their analysis suggest that the energy transfer mechanism should occur due to dipole-dipole interactions among Eu2+ ions, resulting in a shift in emission spectrum toward longer wavelengths with increasing Eu2+ concentration. The quenching concentration of Eu2+ (i.e., where the emission intensity maximizes) is approximately 2 at. %. Accordingly, the produced CaSi2O2N2:Eu2+ green phosphors are qualified for further consideration and experimentation for potential use in white light emitting diodes.
The effect of oxygen during irradiation of silicon with low energy Cs+ ions
Authors: Berghmans B. , Vandervorst W.
Published: August 2009

The effect of oxygen flooding during ultralow energy SIMS depth profiling of silicon with Cs+ primary ions is presented. New experimental data show the effective sputtering yield of silicon in the presence of oxygen, as well as the energy distribution of the secondary Si− ions. It is found that the component sputtering yield of Si is very sensitive to minute amounts of oxygen in the proximity of the sputtered surface. At these very low flooding pressures (in the 10−9–10−8mbar range), one cannot account for a full oxidation in the time frame of a typical measurement; it is concluded that in this particular case, which is technologically very relevant, small traces of oxygen will change the desorption characteristics of cesium as well as silicon. It shows that oxygen that is adsorbed to the silicon surface provides an attachment site for impinging cesium ions and thereby increases the retention capacity of cesium tremendously. Also, oxygen changes the secondary ion yield and can even promote the desorption of Si from the analysis surface.
Na-induced variations in the structural, optical, and electrical properties of Cu(In,Ga)Se2 thin films
Authors: Ishizuka Shogo , Yamada Akimasa , Islam Muhammad Monirul , Shibata Hajime , Fons Paul , Sakurai Takeaki , Akimoto Katsuhiro , Niki Shigeru
Published: August 2009

The systematic variations in the structural, optical, and electrical properties of polycrystalline Cu(In,Ga)Se2 (CIGS) thin films with Na doping level were investigated. Precise control of the Na concentration in CIGS films was demonstrated using alkali-silicate glass thin layers of various thicknesses deposited on substrates prior to CIGS growth. The CIGS grain size was observed to decrease with increasing Na concentration, although the surface morphology became smoother and exhibited a stronger (112) texture, which has been demonstrated consequence of larger grain size. The Ga composition gradient in the CIGS films was found to become large due to the presence of Na during growth, which in turn led to a decrease in the nominal band gap energy. Variations in the photoluminescence spectra and electrical properties suggested that the formation of an acceptor energy state, which may originate from OSe point defects, was enhanced in the presence of Na. This result suggests that not only Na, but also the presence of O in combination with Na contributes to the compensation of point defects and enhances p-type conductivity in CIGS films.
Magnon drag contribution to thermopower of Nd0.67Sr0.33MnO3 nanocrystalline manganites
Authors: Venkataiah G. , Venugopal Reddy P.
Published: August 2009

With a view to investigate the influence of nanosize on thermopower behavior of Nd0.67Sr0.33MnO3 manganites, a systematic investigation of their temperature dependent thermoelectric power (TEP) studies has been undertaken. For this purpose, the samples with different particle sizes were prepared by the sol-gel method by sintering at four different temperatures (viz., 800, 900, 1000, and 1100 °C). The average crystallite sizes were calculated using a modified Scherrer’s formula. The ferromagnetic metallic (FMM) part of the TEP data were fitted to an equation containing diffusion, magnon drag, and phonon drag terms. The relative weights of these contributions were estimated and it has been found that the magnon drag contribution predominantly contributes to the TEP in the FMM region. The phonon drag process in the samples of the present investigation is found to be dominant along the direction of cell parameter “a” than the other two directions. Finally, the paramagnetic insulting part of the TEP data has been analyzed by using small polaron hopping mechanism.
Residual stress analysis in the film/substrate system with the effect of creep deformation
Authors: Chen Qing-Qi , Xuan Fu-Zhen , Tu Shan-Tung
Published: August 2009

The physical phenomenon of residual stress relaxation and redistribution in the film/substrate systems due to creep deformation is focused in this work. A new analysis model to elucidate either the film or the substrate subjected to creeping deformation is developed. Specific analyses are made on the NiCrAlY coating-based system and silicon-epoxy bilayer structure. Results reveal that the proposed model can lead to an excellent agreement with the simulated results of finite element method. Furthermore, comparisons among FE results, the present model, and Zhang’s creep solution [J. Appl. Phys. 101, 083530 (2007)] have been carried out. Meanwhile, comparisons between Hsueh’s viscoelastic solution [J. Appl. Phys. 91, 2760 (2002)] and our current model in the case of creep exponent n=1 have also been conducted. Effects of thickness ratio of the film to the substrate on the stress distribution and the evolution of the accumulated creep strain have also been discussed in this paper.
Revisiting magnetization processes in granular hard magnetic materials
Authors: Dobrynin A. N. , Barthem V. M. T. S. , Givord D.
Published: August 2009

We show that the generally accepted demagnetizing field corrections are not applicable to the broad class of modern granular magnetic materials, where magnetization reversal occurs via discrete switching of the moments of individual grains, and thus the self-demagnetizing field of a given grain is proportional to the spontaneous magnetization Ms, not to the sample magnetization M. This leads to the fact that the self-demagnetizing field must be considered as a contribution to the coercive field and that the slope of the magnetization variation is higher than the classical demagnetizing field slope. This description of demagnetization processes is confirmed by numerical modeling.
The influence of molecular complexity on expanding flows of ideal and dense gases
Authors: Harinck J. , Guardone A. , Colonna P.
Published: August 2009

This paper presents an investigation about the effect of the complexity of a fluid molecule on the fluid dynamic quantities sound speed, velocity, and Mach number in isentropic expansions. Ideal-gas and dense-gas expansions are analyzed, using the polytropic ideal gas and Van der Waals thermodynamic models to compute the properties of the fluid. In these equations, the number of active degrees of freedom of the molecule is made explicit and it is taken as a measure of molecular complexity. The obtained results are subsequently verified using highly accurate multiparameter equations of state. For isentropic expansions, the Mach number does not depend on the molecular weight of the fluid but only on its molecular complexity and pressure ratio. Remarkably enough, the Mach number can either increase or decrease with molecular complexity, depending on the considered pressure ratio. The exit speed of sound and flow velocity, however, are dependent on both molecular complexity and weight, as well as on the inlet total temperature. The exit flow velocity is found to be a monotonically increasing function of molecular complexity for all expansion ratios, whereas the speed of sound monotonically increases with molecular complexity only at high pressure ratios. The speed of sound is not monotone for pressure ratios around 3, which leads to the Mach number being nonmonotone at pressure ratios around 10. It should be noted that the sound speed and flow velocity depend much more strongly on molecular weight than on molecular complexity, which in realistic expansions often obscures the influence of the latter. Quantitative differences are observed between ideal and dense-gas expansions, which are dependent on the reduced inlet conditions. The present study concludes with the numerical simulation of two-dimensional expansions in a turbine nozzle to document the occurrence of real-gas effects and their dependence on molecular complexity in realistic applications.
Directed transport driven by the transverse wall vibration
Authors: Ai Bao-quan
Published: August 2009

Directed transport of overdamped Brownian particles in an asymmetrically periodic tube is investigated in the presence of the tube wall vibration. From the Brownian dynamics simulations we can find that the perpendicular wall vibration can induce a net current in the longitudinal direction when the tube is asymmetric. The direction of the current at low frequency is opposite to that at high frequency. One can change the direction of the current by suitably tailoring the frequency of the wall vibration.
Near-IR vibrational dynamics of periodic gold single and pair nanocuboids
Authors: Wang Li , Nishijima Yoshiaki , Ueno Kosei , Misawa Hiroaki , Tamai Naoto
Published: August 2009

We examined vibrational dynamics of periodic gold single and pair nanocuboids with 9 nm separation at 400 nm excitation by near-IR transient absorption spectroscopy. The similar oscillation periods of coherent phonon vibration (77±1 ps) were observed for both nanocuboids while the damping of the pair was faster than that of the single. From the analysis of bleaching peak shift and finite-difference time-domain calculation, the lattice change in coherent phonon vibration was estimated to be ±1% for a quasiextensional and ±3% for an quasibreathing modes of a single nanocuboid.
Direct detection of grain boundary scattering in damascene Cu wires by nanoscale four-point probe resistance measurements
Authors: Kitaoka Yusuke , Tono Takeshi , Yoshimoto Shinya , Hirahara Toru , Hasegawa Shuji , Ohba Takayuki
Published: August 2009

Four-terminal conductivity measurements of damascene copper (Cu) wires with various widths have been performed using platinum-coated carbon nanotube (CNT) tips in a four-tip scanning tunneling microscope. Using CNT tips enabled the probe spacing to be reduced to 70 nm, which is the shortest probe spacing in interconnect wire measurements achieved so far. The measured resistivity of Cu increased as the line width decreased and direct evidence of individual grain boundary scattering was observed when the probe spacing was varied on a scale comparable to the grain size of the Cu wires (∼200 nm).
Remote sensing for prediction of 1-year post-fire ecosystem condition
Authors: Lentile Leigh B. , Smith Alistair M. S. , Hudak Andrew T. , Morgan Penelope , Bobbitt Michael J. , Lewis Sarah A. , Robichaud Peter R.
Published: August 2009

Appropriate use of satellite data in predicting >1year post-fire effects requires remote measurement of surface properties that can be mechanistically related to ground measures of post-fire condition. The present study of burned ponderosa pine (Pinus ponderosa) forests in the Black Hills of South Dakota evaluates whether immediate fractional cover estimates of char, green vegetation and brown (non-photosynthetic) vegetation within a pixel are improved predictors of 1-year post-fire field measures, when compared with single-date and differenced Normalized Burn Ratio (NBR and dNBR) indices. The modeled estimate of immediate char fraction either equaled or outperformed all other immediate metrics in predicting 1-year post-fire effects. Brown cover fraction was a poor predictor of all effects (r2 < 0.30), and each remote measure produced only poor predictions of crown scorch (r2 < 0.20). Application of dNBR (1 year post) provided a considerable increase in regression performance for predicting tree survival. Immediate post-fire NBR or dNBR produced only marginal differences in predictions of all the 1-year post-fire effects, perhaps limiting the need for prefire imagery. Although further research is clearly warranted to evaluate fire effects data available 2–20 years after fire, char and green vegetation fractions may be viable alternatives to dNBR and similar indices to predict longer-term post-fire ecological effects.
Flatland in flames: a two-dimensional crown fire propagation model
Authors: Dickinson James D. , Robinson Andrew P. , Gessler Paul E. , Harrod Richy J. , Smith Alistair M. S.
Published: August 2009

The canopy bulk density metric is used to describe the fuel available for combustion in crown fire models. We propose modifying the Van Wagner crown fire propagation model, used to estimate the critical rate of spread necessary to sustain active crown fire, to use foliar biomass per square metre instead of canopy bulk density as the fuel input. We tested the efficacy of our proposed model by comparing predictions of crown fire propagation with Van Wagner’s original data. Our proposed model correctly predicted each instance of crown fire presented in the seminal study. We then tested the proposed model for statistical equivalence to the original Van Wagner model using two contemporary techniques to parameterize canopy bulk density. We found the proposed and original models to be statistically equivalent when canopy bulk density was parameterized using the method incorporated in the Fire and Fuels Extension to the Forest Vegetation Simulator (difference < 0.5 km h–1, α = 0.05, n = 2626), but not when parameterized using the method of Cruz and others. Use of foliar biomass per unit area in the proposed model makes for more accurate and easily obtained fuel estimates without sacrificing the utility of the Van Wagner model.
Patterns of post-fire flowering and fruiting in Chlorogalum pomeridianum var. pomeridianum (DC.) Kunth in southern California chaparral
Authors: Borchert Mark , Tyler Claudia M.
Published: August 2009

For many geophytes living in Mediterranean ecosystems, the passage of fire can produce bursts of flowering, seed production, vegetative growth, and seedling recruitment. In the present study, we investigated patterns of flowering and fruit production of the chaparral geophyte Chlorogalum pomeridianum (common soap plant) at two sites: one burned in a prescribed fire and one in nearby unburned chaparral. Both sites burned in a wildfire 2 years later, and we continued monitoring marked plants for an additional 6 years, enabling us to observe the effects of recent reburning on reproduction and growth. We found that flowering was stimulated by fire but was not strictly fire-dependent. There was a positive relationship between bulb size and leaf area, as well as between these two characteristics and flower and fruit production. Flower stalk initiation occurred when plants reached a minimum leaf area of ~1000 cm2, indicating that a minimum bulb size must be reached before reproductive effort is initiated. Direct herbivory of flowering stalks reduced fruiting and leaf herbivory indirectly prevented the initiation of flowering stalks. In the first several years after fire, flower and fruit production could be explained by resource matching but in subsequent years, resource matching was replaced by resource switching.
The cAMP binding protein Epac regulates cardiac myofilament function
Authors: Cazorla Olivier , Lucas Alexandre , Poirier Florence , Lacampagne Alain , Lezoualc'h Frank
Published: August 2009

In the heart, cAMP is a key regulator of excitation–contraction coupling and its biological effects are mainly associated with the activity of protein kinase A (PKA). The aim of this study was to investigate the contribution of the cAMP-binding protein Epac (Exchange protein directly activated by cAMP) in the regulation of the contractile properties of rat ventricular cardiac myocytes. We report that both PKA and Epac increased cardiac sarcomere contraction but through opposite mechanisms. Differently from PKA, selective Epac activation by the cAMP analog 8-(4-chlorophenylthio)-2′-
O
-methyl-cAMP (8-pCPT) reduced Ca
2+
transient amplitude and increased cell shortening in intact cardiomyocytes and myofilament Ca
2+
sensitivity in permeabilized cardiomyocytes. Moreover, ventricular myocytes, which were infected in vivo with a constitutively active form of Epac, showed enhanced myofilament Ca
2+
sensitivity compared to control cells infected with green fluorescent protein (GFP) alone. At the molecular level, Epac increased phosphorylation of 2 key sarcomeric proteins, cardiac Troponin I (cTnI) and cardiac Myosin Binding Protein-C (cMyBP-C). The effects of Epac activation on myofilament Ca
2+
sensitivity and on cTnI and cMyBP-C phosphorylation were independent of PKA and were blocked by protein kinase C (PKC) and Ca
2+
calmodulin kinase II (CaMKII) inhibitors. Altogether these findings identify Epac as a new regulator of myofilament function.
Intimate bacterial–fungal interaction triggers biosynthesis of archetypal polyketides inAspergillus nidulans
Authors: Schroeckh Volker , Scherlach Kirstin , Nützmann Hans-Wilhelm , Shelest Ekaterina , Schmidt-Heck Wolfgang , Schuemann Julia , Martin Karin , Hertweck Christian , Brakhage Axel A.
Published: August 2009

Fungi produce numerous low molecular weight molecules endowed with a multitude of biological activities. However, mining the full-genome sequences of fungi indicates that their potential to produce secondary metabolites is greatly underestimated. Because most of the biosynthesis gene clusters are silent under laboratory conditions, one of the major challenges is to understand the physiological conditions under which these genes are activated. Thus, we cocultivated the important model fungusAspergillus nidulanswith a collection of 58 soil-dwelling actinomycetes. By microarray analyses of bothAspergillussecondary metabolism and full-genome arrays and Northern blot and quantitative RT-PCR analyses, we demonstrate at the molecular level that a distinct fungal-bacterial interaction leads to the specific activation of fungal secondary metabolism genes. Most surprisingly, dialysis experiments and electron microscopy indicated that an intimate physical interaction of the bacterial and fungal mycelia is required to elicit the specific response. Gene knockout experiments provided evidence that one induced gene cluster codes for the long-sought after polyketide synthase (PKS) required for the biosynthesis of the archetypal polyketide orsellinic acid, the typical lichen metabolite lecanoric acid, and the cathepsin K inhibitors F-9775A and F-9775B. A phylogenetic analysis demonstrates that orthologs of this PKS are widespread in nature in all major fungal groups, including mycobionts of lichens. These results provide evidence of specific interaction among microorganisms belonging to different domains and support the hypothesis that not only diffusible signals but intimate physical interactions contribute to the communication among microorganisms and induction of otherwise silent biosynthesis genes.
B-cell activating factor receptor deficiency is associated with an adult-onset antibody deficiency syndrome in humans
Authors: Warnatz Klaus , Salzer Ulrich , Rizzi Marta , Fischer Beate , Gutenberger Sylvia , Böhm Joachim , Kienzler Anne-Kathrin , Pan-Hammarström Qiang , Hammarström Lennart , Rakhmanov Mirzokhid , Schlesier Michael , Grimbacher Bodo , Peter Hans-Hartmut , Eibel Hermann
Published: August 2009

B-cell survival depends on signals induced by B-cell activating factor (BAFF) binding to its receptor (BAFF-R). In mice, mutations in BAFF or BAFF-R cause B-cell lymphopenia and antibody deficiency. Analyzing BAFF-R expression and BAFF-binding to B cells in common variable immunodeficiency (CVID) patients, we identified two siblings carrying a homozygous deletion in the BAFF-R gene. Removing most of the BAFF-R transmembrane part, the deletion precludes BAFF-R expression. Without BAFF-R, B-cell development is arrested at the stage of transitional B cells and the numbers of all subsequent B-cell stages are severely reduced. Both siblings have lower IgG and IgM serum levels but, unlike most CVID patients, normal IgA concentrations. They also did not mount a T-independent immune response against pneumococcal cell wall polysaccharides but only one BAFF-R-deficient sibling developed recurrent infections. Therefore, deletion of the BAFF-R gene in humans causes a characteristic immunological phenotype but it does not necessarily lead to a clinically manifest immunodeficiency.