bluuebunny/crossref_metadata_2025 huggingface dataset:
Recurrence of extreme events with power‐law interarrival times
Authors: Benson David A. , Schumer Rina , Meerschaert Mark M.
Published: August 2007

In various geophysical applications, power‐law interarrival times are observed between extreme events. Classical extreme value theory is based on exponentially distributed interarrivals and can not be applied to these processes. We solve for the density of the maxima of a sequence of random extreme events with any distribution of random interarrivals by applying a continuous time random max model, similar to a random walk model. The equation is exact when the distributions of the exceedances and the interarrivals are known. If only the tail properties of the exceedances and interarrivals can be estimated, then limiting extreme value distributions governing the maximum observation or exceedance are used. The general extreme value densities are obtained by transforming the classical extreme value distributions via subordination. This new class of extreme value densities can be used to obtain recurrence intervals for extreme events with power‐law interarrivals.
Pseudo‐seismic wavelet transformation of transient electromagnetic response in engineering geology exploration
Authors: Xue G. Q. , Yan Y. J. , Li X.
Published: August 2007

This paper presents some new theoretical analysis and numerical simulations of that transient electromagnetic diffusion‐field response is transformed into a pseudo‐seismic wavelet in engineering geology exploration. It can clearly reveal the electric interface under ground. To simplify the integral equation used in the transformation, the integral range is separated into seven windows, and each window is compiled into a group of integral coefficients. Then, the accuracy of the coefficients is tested, and the calculated coefficients are used to derive the pseudo‐seismic wavelet by optimization method. Finally, several geo‐electric models are designed, so that model responses are transformed into the pseudo‐seismic wavelet. The transformed imaginary wave shows that some reflection and refraction phenomena appear when the wave meets the electric interface. This result supports the introduction of the seismic interpretation in data processing of transient electromagnetic method.
Phytoplankton carbon fixation gene (RuBisCO) transcripts and air-sea CO2 flux in the Mississippi River plume
Authors: John David E , Wang Zhaohui A , Liu Xuewu , Byrne Robert H , Corredor Jorge E , López José M , Cabrera Alvaro , Bronk Deborah A , Tabita F Robert , Paul John H
Published: August 2007

River plumes deliver large quantities of nutrients to oligotrophic oceans, often resulting in significant CO2 drawdown. To determine the relationship between expression of the major gene in carbon fixation (large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBisCO) and CO2 dynamics, we evaluated rbcL mRNA abundance using novel quantitative PCR assays, phytoplankton cell analyses, photophysiological parameters, and pCO2 in and around the Mississippi River plume (MRP) in the Gulf of Mexico. Lower salinity (30–32) stations were dominated by rbcL mRNA concentrations from heterokonts, such as diatoms and pelagophytes, which were at least an order of magnitude greater than haptophytes, α-Synechococcus or high-light Prochlorococcus. However, rbcL transcript abundances were similar among these groups at oligotrophic stations (salinity 34–36). Diatom cell counts and heterokont rbcL RNA showed a strong negative correlation to seawater pCO2. While Prochlorococcus cells did not exhibit a large difference between low and high pCO2 water, Prochlorococcus rbcL RNA concentrations had a strong positive correlation to pCO2, suggesting a very low level of RuBisCO RNA transcription among Prochlorococcus in the plume waters, possibly due to their relatively poor carbon concentrating mechanisms (CCMs). These results provide molecular evidence that diatom/pelagophyte productivity is largely responsible for the large CO2 drawdown occurring in the MRP, based on the co-occurrence of elevated RuBisCO gene transcript concentrations from this group and reduced seawater pCO2 levels. This may partly be due to efficient CCMs that enable heterokont eukaryotes such as diatoms to continue fixing CO2 in the face of strong CO2 drawdown. Our work represents the first attempt to relate in situ microbial gene expression to contemporaneous CO2 flux measurements in the ocean.
Novel protein antigen (JHP940) from the genomic plasticity region of Helicobacter pylori induces TNF-alpha and Interleukin- 8 secretion by human macrophages
Authors: Ahmed Niyaz , Alvi Ayesha , Rizwan Mohammed
Published: August 2007

Plasticity region of the H. pylori genome comprises strain specific gene loci. We performed genotyping and functional biology of one such locus (jhp940) that was previously found to be functionally unknown but present in gastric cancer associated strains from many different countries. We found its geographic prevalence to be independent of cagA presence and disease status. Cloning, expression and purification of the JHP940 revealed a novel, ~36kDa protein in biologically active form. The same induced strong and significant levels of TNF-alpha and Interleukin-8 in human macrophages. Induction of these cytokines by JHP940 points to its putative role in chronic gastric inflammation and various other outcomes of H. pylori infection including gastric cancer.
Interaction of low-energy electrons with the pyrimidine bases and nucleosides of DNA
Authors: Winstead Carl , McKoy Vincent , d’Almeida Sanchez Sergio
Published: August 2007

We report computed cross sections for the elastic scattering of slow electrons by the pyrimidine bases of DNA, thymine and cytosine, and by the associated nucleosides, deoxythymidine and deoxycytidine. For the isolated bases, we carried out calculations both with and without the inclusion of polarization effects. For the nucleosides, we neglect polarization effects but estimate their influence on resonance positions by comparison with the results for the corresponding bases. Where possible, we compare our results with experiment and previous calculations.
Large eddy simulation and measurements of turbulent enclosed rotor-stator flows
Authors: Séverac Éric , Poncet Sébastien , Serre Éric , Chauve Marie-Pierre
Published: August 2007

Turbulent flows are studied in an actual enclosed rotor-stator configuration with a rotating hub and a stationary shroud. Besides its fundamental importance—the disk boundary layer is one of the simplest platforms for investigating the underlying structure of three-dimensional boundary layers—this cavity models more complex configurations relevant to rotating machinery. Large eddy simulation is performed using a spectral vanishing viscosity technique that is shown leading to stable discretizations without sacrificing the formal accuracy of the spectral approximation. Numerical results and velocity measurements have been favorably compared for a large range of rotational Reynolds numbers (105⩽Re=Ωb2∕ν⩽106) in an annular cavity of curvature parameter Rm=(b+a)∕(b−a)=1.8 and of aspect ratio G=(b−a)∕h=5, where a and b are, respectively, the inner and outer radii of the rotating disk and h is the interdisk spacing. In the detailed picture of the flow structure that emerges, the turbulence is confined mainly in the boundary layers including in the Stewartson layer along the external cylinder. For Reynolds numbers Re⩾105, the stator boundary layer is turbulent over most of the cavity. On the other hand, the rotor layer becomes progressively turbulent from the outer radial locations, although the rotating hub is shown to destabilize the inner part of the boundary layers. The isosurface maps of the Q-criterion reveal that the three-dimensional spiral arms observed in the unstable laminar regime evolve to more axisymmetric structures when turbulence occurs. At Re=106, the flow is fully turbulent and the anisotropy invariant map highlights turbulence structuring, which can be either a “cigar-shaped” structuring aligned on the tangential direction or a “pancake-shaped” structuring depending on the axial location. The reduction of the structural parameter a1 (the ratio of the magnitude of the shear stress vector to twice the turbulence kinetic energy) under the typical limit 0.15, as well as the misalignment between the shear stress vector and the mean velocity gradient vector, highlight the three-dimensional nature of both rotor and stator boundary layers with a degree of three-dimensionality much higher than in the idealized system studied by Lygren and Andersson [J. Fluid Mech. 426, 297 (2001); ZAMP 55, 268 (2004); and Int. J. Heat Fluid Flow 27, 551 (2006)].
Cluster algorithm to perform parallel Monte Carlo simulation of atomistic systems
Authors: Almarza N. G. , Lomba E.
Published: August 2007

We propose an efficient algorithm to perform Monte Carlo simulations of dense systems using multiple particle moves. The method is intended to be used in the atomistic simulation of complex systems, where the computing requirements for a single simulation run make advisable the use of parallel computing. The algorithm is based on the use of steps in which all the particle positions of the system are perturbed simultaneously. A division of the system in clusters of particles is performed, using a bonding criterion which makes feasible that the acceptance or rejection of the new particle coordinates can be carried out independently for each cluster.
Binding energies of hydrogen-bonded complexes from extrapolation with localized basis sets
Authors: Lee Jae Shin
Published: August 2007

By incorporating effective basis sets containing diffuse functions only in the interaction region of hydrogen-bonded complexes into the simple extrapolation scheme suitable for such basis sets, an accurate estimation of the MP2 basis set limit hydrogen-bonding energies of formic acid tetramer, formamide tetramer, alanine-water, phenol-water, and guanine-cytosine base pair is made with all estimates falling within 0.1–0.3kcal∕mol of the reference basis set limits. The basis sets for extrapolation are composed of the cc-pVDZ and cc-pVDZ plus highest polarization functions from the cc-pVTZ set, or cc-pVDZ and cc-pVTZ set, all of which are augmented by the diffuse functions of the atoms in the interaction region of hydrogen bond. In contrast to the extrapolated estimates by this method, density functional theory binding energies with B3LYP, B971, and TPSS methods yield the differences from the reference values as large as 3.9kcal∕mol with much higher computational cost in most cases, signifying the efficacy of the employed extrapolation scheme for study of large hydrogen-bonded complexes.
Rotationally resolved spectra of jet-cooled RuSi
Authors: Lindholm Ned , Morse Michael D.
Published: August 2007

We report the first gas-phase spectroscopic investigation of diatomic ruthenium silicide (RuSi). The molecules were produced by laser ablation of a Ru disk into a flow of helium carrier gas containing 0.5% SiH4, and were cooled in a supersonic expansion. The RuSi molecules were then studied using resonant two-photon ionization spectroscopy. Investigations conducted in the spectral range from 18800to23800cm−1 show a large number of excited vibronic levels that cannot readily be grouped into electronic band systems. The ground state is been demonstrated to be of Δ33 symmetry, deriving from the 2δ314σ1 electronic configuration. Correcting for the effects of the spin-uncoupling operator, the ground state bond length (r0) is determined to be 2.0921±0.0004Å (1σ error limit). Diatomic RuSi is shown to have strong dπ-pπ bonds, unlike the isovalent AlCo molecule.
Local control theory applied to molecular photoassociation
Authors: Marquetand Philipp , Engel Volker
Published: August 2007

Local control theory (LCT) is employed to achieve molecular photoassociation with shaped laser pulses. Within LCT, the control fields are constructed from the response of the system to the perturbation which makes them accessible to a straightforward interpretation. This is shown regarding the ground-state collision of H+F and H+I atoms. Different objectives are defined, which aim at the formation of vibrational cold or hot associated molecules, respectively. Results are presented for s-wave scattering, where the rotational degree of freedom is ignored and also for full scale calculations including rotations, in order to describe more realistic conditions.
Extrinsic effects in twinned ferroelectric polycrystals
Authors: Pérez Rafel , García Jose E. , Albareda Alfons , Ochoa Diego A.
Published: August 2007

The structure of medium-grain piezoelectric ceramics often consists of alternate lamellae of non-180° domains. In this work, the extrinsic effects of the electric and elastic fields on such structures are studied. A description of the extrinsic behavior of a single grain is given, and it is shown that the relations between piezoelectric and dielectric or elastic constants must be independent of the wall mobility, being solely dependent on the relation between spontaneous polarization and strain. By using an appropriate coordinate system, the conditions under which the intrinsic and extrinsic effects can be added are analyzed. The linear global behavior of a grain can then be described as a function of its orientation and of two additional parameters: the lack of equilibrium between domains α and its mean thickness d. The basis is established to describe the state of a ceramic through a distribution function that accounts for domain orientation and which depends on the poling, fatigue, and ageing of the sample. Finally, the goodness of the model is analyzed, although some aspects must be still modified in order to describe the overall behavior of the ceramic.
Quasielastic electron scattering from methane, methane-d4, methane-d2, ethylene, and 2-methylpropane
Authors: Cooper G. , Christensen E. , Hitchcock A. P.
Published: August 2007

Quasielastic electron scattering from gaseous species at high momentum transfer was recently reported for the first time [Cooper et al., J. Electron Spectrosc. Relat. Phenom. 155, 28 (2007)]. The first results for CH4 and CD4 were well explained by a classical electron Compton scattering picture in which the electron scatters independently from each atom rather than the molecule as a whole. However, an alternative possible interpretation in terms of nondipole molecular vibrational excitation is suggested by previously published quantum mechanical calculations on high momentum transfer electron scattering from diatomic molecules [Bonham and de Souza, J. Chem. Phys. 79, 134 (1983)]. In order to determine which of these two interpretations best fits the experimental results, we have measured the quasielastic spectra of gaseous 2-methylpropane, ethylene, methane, and two isotopically substituted methanes, CH2D2 and CD4, at a momentum transfer of ∼20a.u. (2.25keV impact energy and 100° scattering angle). The experimental spectra are found to be composed of as many peaks as there are different atomic isotopes in the molecule (two for CH4, C2H4, 2-methylpropane, and CD4 and three for CH2D2). The peak positions are predicted accurately by the independent atom electron Compton scattering model, and the relative intensities are in reasonable agreement. The experimental results thus support classical electron Compton scattering as the origin of the signal.
White electroluminescence from a hybrid polymer-GaN:Mg nanocrystals device
Authors: Tan Mingqian , Mahalingam Venkataramanan , van Veggel Frank C. J. M.
Published: August 2007

A magnesium-doped gallium nitride nanocrystal (GaN:Mg NC)-based electroluminescence (EL) device is reported with a hybrid organic/inorganic structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) doped with poly (styrenesulphonic acid) (PEDOT:PSS)/GaN:Mg NCs∕Ca∕Al. The conducting polymer, PEDOT:PSS layer, was used to enhance hole injection from the ITO electrode. Current-voltage characteristics of the GaN:Mg nanocrystal-based EL device show a diodelike behavior. White electroluminescence was observed from the device and a voltage-dependent phenomenon of EL emission spectra was found and investigated. A good correlation between the EL and photoluminescence emission peaks suggests that electron-hole recombination indeed occur in the GaN:Mg nanocrystals layer.
Influence of ZnO seed crystals and annealing on the optical quality of low-temperature grown ZnO nanorods
Authors: Bekeny C. , Voss T. , Hilker B. , Gutowski J. , Hauschild R. , Kalt H. , Postels B. , Bakin A. , Waag A.
Published: August 2007

The influence of ZnO seed crystals and postgrowth annealing on low-temperature aqueous chemically grown ZnO nanorods is analyzed. At the seed crystal/nanorod interface a high density of structural defects leads to emission at 3.332 eV, attributed to excitons bound to structural defects. This peak is absent for seed crystals, very pronounced for rods of shorter lengths grown on seed crystals, and reduced for longer nanorods. After annealing in oxygen and nitrogen atmosphere, the near-band-edge excitonic transitions sharpen and deep-level emission is strongly reduced. Time-resolved photoluminescence measurements show a striking similarity between donor-bound excitons and excitons bound to structural defects.
Induced ferroelectricity in strained epitaxial SrTiO3 films on various substrates
Authors: Wördenweber R. , Hollmann E. , Kutzner R. , Schubert J.
Published: August 2007

The impact of strain on structure and ferroelectric properties of epitaxial SrTiO3 films on various substrate materials—substrates with larger (DyScO3) and smaller (NdGaO3 and CeO2/Al2O3) in-plane lattice constant, respectively—was analyzed. In all cases, (001)-oriented strained epitaxial SrTiO3 was obtained. It is demonstrated that the mismatch of the lattices or, alternatively, the mismatch of the thermal expansion coefficients of films and substrate, imposes biaxial strain on the SrTiO3 films. The strain leads to a small tetragonal distortion of the SrTiO3 lattice and has a large impact on the ferroelectric properties of the films. With decreasing film thickness and at low temperatures the permittivity deviates from the “classical” Curie-Weiss behavior. Furthermore, strain-induced ferroelectricity is observed, which agrees with theoretical predictions. For electric fields parallel to the film, surface-induced ferroelectricity is observed for SrTiO3 that is exposed to in-plane tensile strain, i.e., SrTiO3 on DyScO3 and sapphire. Transition temperatures of To≈210 K and To≈325 K are obtained for SrTiO3 on CeO2/Al2O3 and DyScO3, respectively.
Ultraviolet-visible emission from three-dimensional WO3−x nanowire networks
Authors: Luo Jian Yi , Zhao Fu Li , Gong Li , Chen Huan Jun , Zhou Jun , Li Zheng Lin , Deng Shao Zhi , Xu Ning Sheng
Published: August 2007

The photoluminescence spectra of WO3−x nanowire networks, WO3 nanowires networks, and the bulk phase WO3 powder have been investigated under the continuous wave excitation light at 320nm. Two broad band emissions in spectrum of WO3−x nanowire networks are observed including the ultraviolet-visible (UV-vis) emission centered at 395nm and the blue emission centered at 467nm. The authors demonstrate that the blue emission in WO3−x nanowire networks is due to band-band transition of the bulk phase WO3 and the UV-vis emission is attributed to the state of oxygen vacancies, which are characterized by using scanning electron microscopy and x-ray photoelectron spectroscopy. The UV-vis emission exhibits a strong dependence on the excitation wavelength, while the blue emission is independent of the excitation wavelength. The UV-vis emission is discussed in configuration-coordinate diagram of a localized state of oxygen vacancies. In particular, this state of defect is a high-lying resonant state in the conduction band of WO3.
On-chip matching networks for radio-frequency single-electron transistors
Authors: Xue W. W. , Davis B. , Pan Feng , Stettenheim J. , Gilheart T. J. , Rimberg A. J. , Ji Z.
Published: August 2007

In this letter, the authors describe operation of a radio-frequency superconducting single electron transistor (rf-SSET) with an on-chip superconducting LC matching network consisting of a spiral inductor L and its capacitance to ground Cp. The superconducting network has a lower Cp and gives a better matching for the rf-SSET than does a commercial chip inductor. Moreover, the superconducting network has negligibly low dissipation, leading to sensitive response to changes in the rf-SSET impedance. The charge sensitivity δq=2.4×10−6e∕Hz in the subgap region and energy sensitivity δε=1.9ℏ indicate that the rf-SSET is operating in the vicinity of the shot noise limit.
Thermoluminescence apparatus using PT100 resistors as the heating and sensing elements
Authors: Quilty J. W. , Robinson J. , Appleby G. A. , Edgar A.
Published: August 2007

A novel apparatus for obtaining thermoluminescence glow curves is described. Two standard PT100 precision resistors, which have a well-known dependence of resistance on temperature, are connected back to back to provide a sensing and heating element. The resulting hot finger has very low thermal mass, is nonreactive, and is inexpensive. With dry nitrogen gas-flow cooling, an operational range of −50–450°C is achievable. A tailored control circuit which is easily calibrated drives the heating element, and temperature ramps are implemented in software. The simple design permits the use of modularly interchangeable hot fingers for rapid measurement of many samples.
Increasing the work function of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) by ultraviolet irradiation
Authors: Lin Yow-Jon , Yang Fu-Ming , Huang Chi-Yen , Chou Wei-Yang , Chang Jay , Lien Yi-Chun
Published: August 2007

The effects of ultraviolet (UV) irradiation on the work function of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) have been investigated in this study. Spectroscopic methods [x-ray photoelectron spectroscopy and Raman spectroscopy (532nm excitation)] and electrical conductivity measurements were used to characterize the electrical conducting polymer PEDOT:PSS prepared by UV irradiation. The authors found that UV irradiation could lead to an increase in the work function and the enhancement of electrical conductivity of PEDOT:PSS, resulting from a decrease in the number of the charge-trapping-related defects and the formation of linear or expanded-coil conformation.
Pure spin current in a three-terminal spin device in the presence of Rashba spin-orbit interaction
Authors: Lü Hai-Feng , Guo Yong
Published: August 2007

The authors propose a spin device with three normal metal leads via a quantum dot in the presence of Rashba spin-orbit interaction, which operates independently on a magnetic field or ferromagnetic metals. It is shown that a pure spin current or a fully spin-polarized current can be obtained by modulating one of the voltages applied to three terminals. It further demonstrates the dependence of the pure spin current on the strength of Rashba spin-orbit interaction and the configuration of the three leads.
Pt nanocrystals formed by ion implantation: A defect-mediated nucleation process
Authors: Giulian R. , Kluth P. , Araujo L. L. , Llewellyn D. J. , Ridgway M. C.
Published: August 2007

The influence of ion irradiation of SiO2 on the size of metal nanocrystals (NCs) formed by ion implantation has been investigated. Thin SiO2 films were irradiated with high-energy Ge ions then implanted with Pt ions. Without Ge irradiation, the largest Pt NCs were observed beyond the Pt projected range. With irradiation, Ge-induced structural modification of the SiO2 layer yielded a decrease in Pt NC size with increasing Ge fluence at such depths. A defect-mediated NC nucleation mechanism is proposed and a simple yet effective means of modifying and controlling the Pt NC size is demonstrated.
Technique for anisotropic extension of organic crystals: Application to temperature dependence of electrical resistance
Authors: Yamamoto Takashi , Kato Reizo , Yamamoto Hiroshi M. , Fukaya Atsuko , Yamasawa Kenji , Takahashi Ichiro , Akutsu Hiroki , Akutsu-Sato Akane , Day Peter
Published: August 2007

We have developed a technique for the anisotropic extension of fragile molecular crystals. The pressure medium and the instrument, which extends the pressure medium, are both made from epoxy resin. Since the thermal contraction of our instrument is identical to that of the pressure medium, the strain applied to the pressure medium has no temperature dependence down to 2K. Therefore, the degree of extension applied to the single crystal at low temperatures is uniquely determined from the degree of extension in the pressure medium and thermal contractions of the epoxy resin and the single crystal at ambient pressure. Using this novel instrument, we have measured the temperature dependence of the electrical resistance of metallic, superconducting, and insulating materials. The experimental results are discussed from the viewpoint of the extension (compression) of the lattice constants along the parallel (perpendicular) direction.
Electron transport properties in ZnO nanowire array/nanoparticle composite dye-sensitized solar cells
Authors: Ku Chen-Hao , Wu Jih-Jen
Published: August 2007

A significant improvement of the efficiency of the ZnO nanowire (NW) dye-sensitized solar cell (DSSC) has been achieved by the chemical bath deposition of the dense nanoparticles (NPs) within the interstices of the vertical ZnO-NW anode. Impedance analyses of the electron transports in DSSCs reveal that the effective diffusion coefficient of an electron in the ZnO-NW array/NP composite anode falls between those in the ZnO-NW and TiO2-NP anodes. The superior performance of the ZnO-NW array/NP composite DSSC to the ZnO-NW cell is mainly ascribed to the enrichment of the light harvesting without significantly sacrificing the electron transport efficiency.
High response organic visible-blind ultraviolet detector
Authors: Ray Debdutta , Narasimhan K. L.
Published: August 2007

The authors demonstrate a high efficiency visible-blind ultraviolet organic photodetector with a response of 30mA∕W. The active layer is a blend of N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TPD) and tris(8-hydroxyquinoline) aluminum (Alq3). The authors show that the spontaneous as well as the electric field induced carrier generation efficiencies in the blend are enhanced over its constituents. The spontaneous carrier generation efficiency measured from total carrier collection measurements is 30% in the blend. The photoluminescence of the blend shows an efficient energy transfer from the TPD to Alq3 molecule. The mobility-lifetime (μτ) product in the blend is 2.2×10−12cm2∕V. The μτ product is weakly dependent on temperature.
Bipolar resistive switching in a single layer memory device based on a conjugated copolymer
Authors: Hong Sang-Hyun , Kim Ohyun , Choi Seungchel , Ree Moonhor
Published: August 2007

The feasibility of employing polymer memory devices as future data-storage units was investigated by using thin films of a π-conjugated copolymer, namely, poly(o-anthranilic acid-co-o-nitroaniline), which can be obtained by low-cost solution processing. Investigations on the conjugated-copolymer film showed that the hysteresis in the current-voltage characteristics can be used to perform “write-read-erase-read” memory functions. In addition, the ratio of the on/off current depended on the switching-on compliance current and the maximum voltage applied. This study suggests that the resistive switching of the copolymer device can be attributed to trap charging and discharging, which induce localized filament formation and disappearance.
Large impact of strontium substitution on photocatalytic water splitting activity of BaSnO3
Authors: Yuan Yupeng , Lv Jun , Jiang Xiaojun , Li Zhaosheng , Yu Tao , Zou Zhigang , Ye Jinhua
Published: August 2007

The effects of Sr substitution for Ba on photocatalytic water splitting activity of BaSnO3 were investigated experimentally and theoretically. The chemical incorporation of Sr into BaSnO3 induced a great enhancement for H2 production. Density function theory calculations of Ba1−xSrxSnO3 (x=0, 0.5, and 1.0) reveal that the bottom of the conduction band is gradually pushed up and the contribution of the Sr 5s orbitals to the bottom of the conduction band gradually becomes dominant with the increase of Sr concentration from x=0 to x=1.0. The participation of the normally inert Sr cation in the electronic structure of the SnO32− framework not only enhances the reduction ability of photoinduced electrons but also provides favorable opportunities for charge carrier transport, thus enhancing the photocatalytic activity of BaSnO3.
Cu
B
O
2
: A p-type transparent oxide
Authors: Snure Michael , Tiwari Ashutosh
Published: August 2007

The authors report the synthesis of CuBO2, a p-type transparent oxide belonging to Cu-delafossite family. High quality thin films of CuBO2 were deposited on c-plane sapphire substrates by pulsed laser deposition technique. Detailed structural, optical, and electrical characterizations on these films were performed. Optical transmission measurement showed the films to be highly transparent in the visible range and having indirect and direct band gaps of 2.2 and 4.5eV, respectively. Room-temperature electrical conductivity of CuBO2 films was 1.65Scm−1 and exhibited semiconductorlike temperature dependence. The Hall and Seebeck coefficients of the film were positive, indicating the p-type nature of the material.
Heteroepitaxial growth of quantum wire arrays through prepatterning substrate surfaces
Authors: Liu Ping , Lu Chun , Zhang Yong-Wei , Lam Khin-Yong
Published: August 2007

The present work uses three-dimensional computer simulations to investigate the formation of regularly distributed quantum wire arrays via heteroepitaxial growth on prepatterned substrate surfaces. It is found that the propagation of a wavelike surface configuration due to the surface mass diffusion driven by the nonuniform stress distribution dictates the formed wire morphology. Several types of quantum wire arrays can be obtained by controlling growth and prepattern parameters. The formation of these ordered surface structures can be explained by the wavelike propagation of the surface configurations and the evolution of the surface chemical potential during growth.
Study of selective amorphous silicon etching to silicon nitride using a pin-to-plate dielectric barrier discharge in atmospheric pressure
Authors: Kyung Se-Jin , Park Jae-Beom , Lee June-Hee , Lim Jong-Tae , Yeom Geun-Young
Published: August 2007

Remote-type atmospheric pressure plasmas were generated using a modified dielectric barrier discharge with the powered electrode consisting of multipins instead of a conventional blank planar plate. For the N2∕NF3 gas mixture, a high etch rate of a:Si close to 115nm∕s was obtained by adding 300SCCM (SCCM denotes cubic centimeter per minute at STP) of NF3 to N2 [50SLM (standard liters per minute)] at an ac rms voltage of 8.5kV (2.5kW, 30kHz). However, the selectivity of a:Si to Si3N4 was as low as 1.3. A selectivity of a:Si∕Si3N4>5.0 could be obtained while maintaining an etch rate of a:Si at 110nm∕s by adding 250SCCM CF4 to the N2 (50SLM)∕NF3 (300SCCM) mixture through the formation of a C–F polymer layer preferentially on the Si3N4 surface.
Genetic evaluation of crossbred lamb production. 4. Genetic parameters for first-cross animal performance
Authors: Ingham V. M. , Fogarty N. M. , Gilmour A. R. , Afolayan R. A. , Cummins L. J. , Gaunt G. M. , Stafford J. , Edwards J. E. Hocking
Published: August 2007

The study estimated heritability for lamb growth and carcass performance, hogget ewe wool production, and worm egg count among crossbred progeny of maternal breed sires, as well as the genetic and phenotypic correlations among the traits. The data were from crossbred progeny of 91 sires from maternal breeds including Border Leicester, East Friesian, Finnsheep, Coopworth, White Suffolk, Corriedale, and Booroola Leicester. The sires were mated to Merino ewes at 3 sites over 3 years (and also Corriedale ewes at one site), with 3 common sires used at each site and year to provide genetic links. These sheep comprised part of the national maternal sire central progeny test program (MCPT) to evaluate the genetic variation for economically important production traits in progeny of maternal and dual-purpose (meat and wool) sires and the scope for genetic improvement. The matings resulted in 7846 first-cross lambs born, with 2964 wether lambs slaughtered at an average age of 214 days, and wool data from 2795 hogget ewes. Data were analysed using univariate mixed models containing fixed effects for site, year, sex and type of birth and rearing, dam source and sire breed, and random terms for sire and dam effects. Heritabilities and genetic correlations were estimated based on variances from progeny of 70 sires by fitting the same mixed models using a REML procedure in univariate and multivariate analyses. Estimates of heritability were low for lamb growth traits (0.07–0.29), meat colour and meat pH (0.10–0.23), and faecal worm egg count (0.10), moderate for carcass fat and muscle traits (0.32–0.47), and moderate to high for wool traits (0.36–0.55). Estimates of direct genetic correlations among liveweights at various ages were high and positive (0.41–0.77) and those between liveweights and most carcass and meat quality traits were small and varied in sign. Liveweights were moderately to highly positively correlated with most wool traits, except fibre diameter (–0.28–0.08). The study indicates that there is genetic variation for wool, growth, carcass, and meat quality traits, as well as for faecal worm egg count, with scope for selection within Australian maternal sire breeds of sheep.
Conformational instability of the MARK3 UBA domain compromises ubiquitin recognition and promotes interaction with the adjacent kinase domain
Authors: Murphy James M. , Korzhnev Dmitry M. , Ceccarelli Derek F. , Briant Douglas J. , Zarrine-Afsar Arash , Sicheri Frank , Kay Lewis E. , Pawson Tony
Published: August 2007

The Par-1/MARK protein kinases play a pivotal role in establishing cellular polarity. This family of kinases contains a unique domain architecture, in which a ubiquitin-associated (UBA) domain is located C-terminal to the kinase domain. We have used a combination of x-ray crystallography and NMR dynamics experiments to understand the interaction of the human (h) MARK3 UBA domain with the adjacent kinase domain as compared with ubiquitin. The x-ray crystal structure of the linked hMARK3 kinase and UBA domains establishes that the UBA domain forms a stable intramolecular interaction with the N-terminal lobe of the kinase domain. However, solution-state NMR studies of the isolated UBA domain indicate that it is highly dynamic, undergoing conformational transitions that can be explained by a folding–unfolding equilibrium. NMR titration experiments indicated that the hMARK3 UBA domain has a detectable but extremely weak affinity for mono ubiquitin, which suggests that conformational instability of the isolated hMARK3 UBA domain attenuates binding to ubiquitin despite the presence of residues typically involved in ubiquitin recognition. Our data identify a molecular mechanism through which the hMARK3 UBA domain has evolved to bind the kinase domain, in a fashion that stabilizes an open conformation of the N- and C-terminal lobes, at the expense of its capacity to engage ubiquitin. These results may be relevant more generally to the 30% of UBA domains that lack significant ubiquitin-binding activity, and they suggest a unique mechanism by which interaction domains may evolve new binding properties.
Aryl hydrocarbon receptor nuclear translocator-like (BMAL1) is associated with susceptibility to hypertension and type 2 diabetes
Authors: Woon Peng Y. , Kaisaki Pamela J. , Bragança José , Bihoreau Marie-Thérèse , Levy Jonathan C. , Farrall Martin , Gauguier Dominique
Published: August 2007

Many aspects of physiology and behavior follow a circadian rhythm. Brain and muscle Arnt-like protein-1 (BMAL1) is a key component of the mammalian molecular clock, which controls circadian oscillations. In the rat, the gene encodingBmal1is located within hypertension susceptibility loci. We analyzed the SNP distribution pattern in a congenic interval associated with hypertension in the spontaneously hypertensive rat (SHR), and we show thatBmal1maps close to a region genetically divergent between SHR and its normotensive (Wistar–Kyoto) counterpart.Bmal1sequencing in rat strains identified 19 polymorphisms, including an SHR promoter variant that significantly affects Gata-4 activation of transcription in transient transfection experiments. A genetic association study designed to test the relevance of these findings in 1,304 individuals from 424 families primarily selected for type 2 diabetes showed that twoBMAL1haplotypes are associated with type 2 diabetes and hypertension. This comparative genetics finding translated from mouse and rat models to human provides evidence of a causative role ofBmal1variants in pathological components of the metabolic syndrome.
Transcriptome-wide analysis of blood vessels laser captured from human skin and chronic wound-edge tissue
Authors: Roy Sashwati , Patel Darshan , Khanna Savita , Gordillo Gayle M. , Biswas Sabyasachi , Friedman Avner , Sen Chandan K.
Published: August 2007

Chronic wounds represent a substantial public health problem. The development of tools that would enable sophisticated scrutiny of clinical wound tissue material is highly desirable. This work presents evidence enabling rapid specific identification and laser capture of blood vessels from human tissue in a manner which lends itself to successful high-density (U133A) microarray analysis. Such screening of transcriptome followed by real-time PCR and immunohistochemical verification of candidate genes and their corresponding products were performed by using 3 mm biopsies. Of the 18,400 transcripts and variants screened, a focused set of 53 up-regulated and 24 down-regulated genes were noted in wound-derived blood vessels compared with blood vessels from intact human skin. The mean abundance of periostin in wound-site blood vessels was 96-fold higher. Periostin is known to be induced in response to vascular injury and its expression is associated with smooth muscle cell differentiation
in vitro
and promotes cell migration. Forty-fold higher expression of heparan sulfate 6-
O
-endosulfatase1 (Sulf1) was noted in wound-site vessels. Sulf1 has been recently recognized to be anti-angiogenic. During embryonic vasculogenesis, CD24 expression is down-regulated in human embryonic stem cells. Wound-site vessels had lower CD24 expression. The findings of this work provide a unique opportunity to appreciate the striking contrast in the transcriptome composition in blood vessels collected from the intact skin and from the wound-edge tissue. Sets of genes with known vascular functions but never connected to wound healing were identified to be differentially expressed in wound-derived blood vessels paving the way for innovative clinically relevant hypotheses.
Diffusion-weighted magnetic resonance imaging of cerebrospinal fluid in patients with and without communicating hydrocephalus
Authors: Našel C. , Gentzsch S. , Heimberger K.
Published: August 2007

Background: Recent concepts about cerebrospinal fluid (CSF) circulation in communicating hydrocephalus (CoHy), which is also termed “restricted arterial pulsation hydrocephalus,” suggest reduced arterial pulsations of subarachnoid vessels with a smaller amount of CSF shifted in subarachnoid spaces during the early systole. The postulated restriction of subarachnoid arterial pulsations in CoHy should induce a smaller motion artifact and reduced local stream effects in CSF in magnetic resonance (MR) diffusion-weighted imaging (DWI).

Purpose: To investigate the maximum diffusivity in CSF in patients with and without CoHy using DWI.

Material and Methods: 12 patients without CSF circulation disturbances and six cases with proven CoHy were assessed. Diffusion was measured in six noncollinear directions without triggering the arterial pulse wave (scan time 6:45 min, voxel size 2×2×2 mm). Due to expected artifacts, the calculated maximum diffusivity was called apparent diffusivity. Regional high and low apparent diffusivity was assessed in CSF spaces on newly created 3D CSF motion maps.

Results: Patients with regular CSF circulation exhibited high apparent diffusivity in CSF in basal subarachnoid spaces, whereas apparent diffusivity was low there in patients with CoHy.

Conclusion: DWI opens a feasible approach to study CSF motion in the neurocranium. Restricted arterial pulsations seem to be involved in CoHy.
Screening for carotid injury in trauma patients: image quality of 16-detector-row computed tomography angiography
Authors: Borisch I. , Boehme T. , Butz B. , Hamer O. W. , Feuerbach S. , Zorger N.
Published: August 2007

Background: The introduction of multidetector-row computed tomography (MDCT) has revolutionized the initial management of multiply injured patients. This technology has the potential to improve the imaging of traumatic vascular injuries.

Purpose: To evaluate the quality of multidetector-row computed tomography angiography (MDCTA) of the carotid arteries in the setting of a routine whole-body trauma scan.

Material and Methods: 87 trauma patients underwent a routine whole-body CT scan in a 16-detector-row scanner including an MDCTA with a reconstructed axial slice thickness of 3 mm. Images were reviewed by three experienced radiologists with emphasis on image quality. Contrast density, severity, and origin of artifacts and the occurrence of vessel lesions were assessed for different vessel segments.

Results: 3642 separate vessel segments were evaluated. Contrast density was rated good or sufficient for diagnosis in 99.8%. A total of 67.3% of vessel segments were free of artifacts, while 27.9% of vessel segments showed minor artifacts not impairing diagnostic evaluation. Clinically relevant artifacts obscuring a vessel segment occurred in 4.7% and were mostly caused by dental hardware. Four dissections of the internal carotid artery were diagnosed by all three radiologists.

Conclusion: As a rapid screening test for blunt carotid artery injury, integration of MDCTA in the routine imaging workup of trauma patients utilizing a whole-body CT trauma scan is possible and practicable. Image quality is mostly sufficient for diagnosis, but impaired in a few cases by artifacts deriving primarily from dental hardware.
On‐line processing of wh‐questions in children with G‐SLI and typically developing children
Authors: Marinis Theodoros , van der Lely Heather K. J.
Published: August 2007

Background: The computational grammatical complexity (CGC) hypothesis claims that children with G(rammatical)‐specific language impairment (SLI) have a domain‐specific deficit in the computational system affecting syntactic dependencies involving ‘movement’. One type of such syntactic dependencies is filler‐gap dependencies. In contrast, the Generalized Slowing Hypothesis claims that SLI children have a domain‐general deficit affecting processing speed and capacity.

Aims: To test contrasting accounts of SLI we investigate processing of syntactic (filler‐gap) dependencies in wh‐questions.

Methods & Procedures: Fourteen 10;2–17;2 G‐SLI children, 14 age‐matched and 17 vocabulary‐matched controls were studied using the cross‐modal picture‐priming paradigm.

Outcomes & Results: G‐SLI children's processing speed was significantly slower than the age controls, but not younger vocabulary controls. The G‐SLI children and vocabulary controls did not differ on memory span. However, the typically developing and G‐SLI children showed a qualitatively different processing pattern. The age and vocabulary controls showed priming at the gap, indicating that they process wh‐questions through syntactic filler‐gap dependencies. In contrast, G‐SLI children showed priming only at the verb.

Conclusions: The findings indicate that G‐SLI children fail to establish reliably a syntactic filler‐gap dependency and instead interpret wh‐questions via lexical–thematic information. These data challenge the Generalized Slowing Hypothesis account, but support the CGC hypothesis, according to which G‐SLI children have a particular deficit in the computational system affecting syntactic dependencies involving ‘movement’. As effective remediation often depends on aetiological insight, the discovery of the nature of the syntactic deficit, along side a possible compensatory use of semantics to facilitate sentence processing, can be used to direct therapy. However, the therapeutic strategy to be used, and whether such similar strengths and weaknesses within the language system are found in other SLI subgroups are empirical issues that warrant further research.
Heat diffusion across a local stochastic magnetic field
Authors: Yu Q.
Published: August 2007

Based on the earlier work for a single magnetic island and a weak stochastic magnetic field (Yu 2006Phys. Plasmas13062310), the heat diffusion across a local fully stochastic magnetic field is studied numerically and compared with the analytical theories. The ratio between the parallel and the perpendicular heat diffusivity, χ||/χ⊥, is found to be an important parameter in characterizing the transport. With the increase in χ||/χ⊥, the transport is dominated first by the additive effect of individual islands and then by the field ergodicity and χ||.
Steady-state operation and high energy particle production of MeV energy in the Large Helical Device
Authors: Mutoh T. , Kumazawa R. , Seki T. , Saito K. , Kasahara H. , Nakamura Y. , Masuzaki S. , Kubo S. , Takeiri Y. , Shimozuma T. , Yoshimura Y. , Igami H. , Watanabe T. , Ogawa H. , Miyazawa J. , Shoji M. , Ashikawa N. , Nishimura K. , Osakabe M. , Tsumori K. , Ikeda K. , Nagaoka K. , Oka Y. , Chikaraishi H. , Funaba H. , Morita S. , Goto M. , Inagaki S. , Narihara K. , Tokuzawa T. , Sakamoto R. , Morisaki T. , Peterson B.J. , Tanaka K. , Nakanishi H. , Nishiura M. , Ozaki T. , Shimpo F. , Nomura G. , Takahashi C. , Yokota M. , Zhao Y.P. , Kwak J.G. , Murakami S. , Okada H. , Yamada H. , Kawahata K. , Ohyabu N. , Kaneko O. , Ida K. , Nagayama Y. , Watanabe K.Y. , Noda N. , Komori A. , Sudo S. , Motojima O.
Published: August 2007

Achieving steady-state plasma operation at high plasma temperatures is one of the important goals of worldwide magnetic fusion research. High temperatures of approximately 1–2 keV, and steady-state plasma sustainment operations have been reported. Recently the steady-state operation regime was greatly extended in the Large Helical Device (LHD). A high-temperature plasma was created and maintained for 54 min with 1.6 GJ in the 2005FY experimental programme. The three-dimensional heat-deposition profile of the LHD helical divertor was modified, and during long-pulse discharges it effectively dispersed the heat load using a magnetic axis swing technique developed at the LHD. A sweep of only 3 cm in the major radius of the magnetic axis position (less than 1% of the major radius of the LHD) was enough to disperse the divertor heat load. The steady-state plasma was heated and sustained mainly by hydrogen minority ion heating using ion cyclotron range of frequencies and partially by electron cyclotron of fundamental resonance frequency. By accumulating the small flux of charge-exchanged neutral particles during the long-pulse operation, a high energy ion tail which extended up to 1.6 MeV was observed. This is the first experimental evidence of high energetic ion confinement of MeV range in helical devices. The long-pulse operations lasted until a sudden increase in radiation loss occurred, presumably because of metal wall flakes dropping into the plasma. The sustained line-averaged electron density and temperature were approximately 0.8 × 1019 m−3and 2 keV, respectively, at a 1.3 GJ discharge (#53776) and 0.4 × 1019 m−3and 1 keV at a 1.6 GJ discharge (#66053). The average input power was 680 kW and 490 kW, and the plasma duration was 32 min and 54 min, respectively. These successful long operations show that the heliotron configuration has a high potential as a steady-state fusion reactor.