bluuebunny/crossref_metadata_2025 huggingface dataset:
Presidential Elements in Government Poland – semi-presidentialism or ‘rationalised parliamentarianism’?
Authors: Wyrzykowski Miroslaw , Cieleń Agnieszka
Published: July 2006

Polish constitutional tradition concerning system of government mainly parliamentarian – Round Table before the Fall of the Wall in 1989 as explanation for the role attributed to the President – development towards a variety of ‘rationalised parliamentarianism’ with a relatively strong role for prime-minister in the 1997 Constitution – system of government not really semi-presidential in nature
Court of Justice of the European Communities
Authors: Spinellis Dionysios
Published: July 2006

The judgment of the European Court of Justice of 13 September 2005 decided an important institutional conflict in the Union. At the request of the Commission, the Court annulled the Council’s Framework Decision 2003/80/JHA on the protection of the environment through criminal law. In so doing, the Court acknowledged that the member states can be obliged under Community law and its system of conditions to impose criminal sanctions if this is necessary to protect Community law. It is beyond doubt that they thus can be obliged under Union law and its conditions. The underlying questions are about the relationship between the first and third pillars and the logic of each.
Kontextspezifische Emotionsregulationsstile
Authors: Knollmann Martin
Published: July 2006

Zusammenfassung. Der “Fragebogen zur Emotionsregulation im Lernkontext Mathematik (FERL-M)” erfasst den lernkontextspezifischen emotionalen Regulationsstil von Lernenden. Insgesamt vier Skalen messen den funktionalen und dysfunktionalen Umgang mit Freude und negativen Lernemotionen (Ärger, Angst, Enttäuschung) während des Mathematiklernens. Zur Überprüfung der Reliabilität und Validität wurden zwei Stichproben gezogen (Stichprobe A: N = 180, 5. bis 7. Klasse; B: N = 181, 6. Klasse). Die Ergebnisse explorativer und konfirmatorischer Faktorenanalysen sprechen für die angenommene Struktur; die internen Konsistenzen der Skalen waren zufrieden stellend bis gut. Ferner weist ein Experten-Rating auf eine hohe inhaltliche Validität hin. An Stichprobe B erhobene Korrelationen der Skalen mit motivationalen Schülermerkmalen sowie der Schulleistung zeigen erwartungsgemäße Zusammenhänge zwischen den Konstrukten, die die Eignung des FERL-M für lehr-lernbezogene Untersuchungen der Emotionsregulation jenseits der Stressverarbeitung belegen.
Heliospheric ion energization due to emerging CME shocks
Authors: Roth I. , Bale S. D.
Published: July 2006

Formation of inhomogeneous electromagnetic structures with gradients in magnetic field and intrinsic electric fields is commonly observed in magnetized plasmas. Heliospheric plasmas are susceptible to formation of localized, supersonically propagating electromagnetic inhomogeneities. Coronal relaxation may result in an emergence close to solar surface of a shock wave which traverses significant parts of the heliosphere. Shocks of solar origin may accelerate ions to high energies, and some of these ions can be trapped in quasi‐stable orbits of planetary magnetospheres. The observationally deduced ion acceleration close to the Sun, at low Mach numbers and low turbulence levels, poses a dilemma regarding the energization mechanism. When the magnetic ramp of an obliquely propagating electromagnetic substructure narrows to a size of a fraction of ion skin depth, as conjectured during merging of successively propagating shocks, the trajectories of some ions exhibit strongly nonadiabatic characteristics. Subset of ions is energized while surfing along the shock due to the combined forces of magnetic fields and cross‐shock electric potential gradient, forming a high‐energy tail. This tail may be additionally accelerated after traversing the shock multiple times as a result of scattering and reflection due to Alfvenic wave diffusion. We follow the orbits of seed ions in a presence of a stationary, fluid‐based, self‐consistent model, and investigate their behavior for a variety of plasma parameters and geometries. The results indicate that (1) the energization of ions for low Mach numbers, as observed for emerging shocks close to the Sun, depends crucially on the narrowness of the electromagnetic structures, (2) the sufficiently narrow heliospheric structure can energize thermal protons and a subset of rare ions which were enriched due to impulsive coronal processes, (3) the energization is sensitive to the pitch angle of the seed population, indicating dependence on the geometry of the shock‐plasma flow system, and (4) the preacceleration by surfing mechanism is a prerequisite for an additional energization due to diffusive shock acceleration. We conclude that the best configuration for an effective acceleration due to an emerging shock at small heliocentric distances and low Mach number consists of a narrow electromagnetic substructure which energizes heliospheric thermal protons directly from their thermal level, as well as trace elements which enrich the seed population due to previous coronal processes. The narrowness of the shock or its substructure and the surfing mechanism may help in explaining the observed energization when other mechanisms become inefficient due to an insufficient level of the turbulence. The energetic ion populations may have a direct profound impact on human space exploration.
Parallel electron streaming in the high‐latitude E region and its effect on the incoherent scatter spectrum
Authors: Bahcivan H. , Cosgrove R. B. , Tsunoda R. T.
Published: July 2006

This article investigates the combined electron heating and streaming effects of low‐frequency parallel electric fields on the incoherent scatter measurements of the high‐latitude E region. The electric fields distort the electron distribution function, inducing changes on the amplitude and frequency of the ion‐acoustic line in the measured incoherent scatter spectrum. If one assumes Maxwellian electrons, the measurements of electron and ion temperatures and electron density are subject to significant percentage errors during geomagnetically active conditions.
Examination of ozonesonde data for trends and trend changes incorporating solar and Arctic oscillation signals
Authors: Miller Alvin J. , Cai Airong , Tiao George , Wuebbles Donald J. , Flynn Lawrence E. , Yang Shi‐Keng , Weatherhead Elizabeth C. , Fioletov Vitali , Petropavlovskikh Irina , Meng Xiao‐Li , Guillas Serge , Nagatani Ronald M. , Reinsel Gregory C.
Published: July 2006

One major question that arises with the implementation of the Montreal Protocol and its subsequent conventions is our ability to determine that an ozone “recovery” is in process. Toward this we have utilized a statistical model suggested by Reinsel et al. (2002) that utilizes the idea of a trend and a trend change at a specific time and applied it to 12 ozonesonde stations in the midlatitudes of the Northern Hemisphere. The lower stratosphere, in particular, is of significance as this is where the ozone concentration is a maximum and also where heterogeneous ozone losses have been noted. This statistical methodology suffers, however, from the ambiguities of having to select a specific time for the ozone trend to change and the fact that the Mt Pinatubo volcanic aerosols impacted the ozone amount. Within this paper, we analyze the ozonesonde station data utilizing the above model but examine the statistical stability of the computed results by allowing the point of inflection to change from 1995 through 2000 and also exclude varying amounts of data from the post‐Pinatubo period. The results indicate that while the impacts of deleting data and changing the inflection point are nontrivial, the overall results are consistent in that there has been a major change in the ozone trend in the time frame of 1996 and that a reasonable scenario is to utilize a change point in 1996 and exclude 2 years of data after the 1991 Mt. Pinatubo eruption. In addition, we include a term for the Arctic oscillation within the statistical model and demonstrate that it is statistically significant.
Volumetric behavior of saturated sands under poor drainage conditions
Authors: Lourenço Sérgio D. N. , Wang Gonghui , Sassa Kyoji , Fukuoka Hiroshi
Published: July 2006

Permeability variations have been identified as a key factor in controlling slope failure locations in rainfall‐induced landslides. In this research, failure behavior in limited drainage conditions was investigated. Tests were performed on saturated sands by means of a modified triaxial system that could mimic the effect of low‐permeability barriers present in the field. The tests were conducted by increasing the pore water pressure at different rates to study the effects of the speed of pore water pressure rise on soil failure. The results revealed a dependence of soil volume changes on the rate of pore water pressure increase. In general, the results showed that volume change of granular soils, which are under shear and confined laterally by low‐permeability materials, depends on the initial porosity and the pore water pressure rate. These results are particularly valid during the early stages of soil deformation that precede wholesale slope failure.
Structure of the San Andreas Fault at SAFOD from P‐wave tomography and fault‐guided wave mapping
Authors: Malin Peter , Shalev Eylon , Balven Heather , Lewis‐Kenedi Catherine
Published: July 2006

Fault‐guided waves reveal a low‐velocity fault segment a few hundred meters southwest of the main strand of the San Andreas Fault (SAF) system. In 2004, the San Andreas Fault Observatory at Depth (SAFOD) Main Hole was drilled 2.5 km underground and 0.7 km west of the SAF surface trace. A 3‐component, 4.5‐Hz seismograph was installed near the bottom of this hole. This instrument recorded fault zone guided (Fg) waves originating from earthquakes along the main SAF ∼2 km north and 3 km south of the SAFOD site. This ∼5 km length corresponds to a distinctive low‐velocity structure imaged in 2003 using microearthquakes recorded on the Pilot Hole array. Because this structure transmits Fg‐waves from the main fault, it is probably connected to the main SAF and is most likely a major, unmapped fault.
A study on the stability of a baroclinic flow in cyclostrophic balance on the sphere
Authors: Takagi M. , Matsuda Y.
Published: July 2006

A three‐dimensional primitive equation model on a sphere is constructed to investigate stability of a baroclinic flow in cyclostrophic balance and structures of the unstable modes. When the Richardson number is large, the baroclinic instability appears for sufficiently small values of the Rossby number. As the Rossby number increases, only the large scale modes remain unstable and amplitude of these modes becomes confined to the lower layer. When the Richardson number is small, the symmetric instability predominates, while the baroclinic instability modes also exist in a certain parameter range. Unlike the baroclinic instability mode, the amplitude of the symmetric instability mode is confined to low latitudes in the upper layer. Since the Richardson number is small in the Venus cloud layer, it is predicted that the baroclinic instability is suppressed in the midlatitudes, and the symmetric instability appears in the low latitudes.
Alpine glaciers to disappear within decades?
Authors: Zemp Michael , Haeberli Wilfried , Hoelzle Martin , Paul Frank
Published: July 2006

Past, present and potential future glacier cover in the entire European Alps has been assessed from an integrated approach, combining in‐situ measurements, remote sensing techniques and numerical modeling for equilibrium line altitudes. Alpine glaciers lost 35% of their total area from 1850 until the 1970s, and almost 50% by 2000. Total glacier volume around 1850 is estimated at some 200 km3 and is now close to one‐third of this value. From the model experiment, we show that a 3°C warming of summer air temperature would reduce the currently existing Alpine glacier cover by some 80%, or up to 10% of the glacier extent of 1850. In the event of a 5°C temperature increase, the Alps would become almost completely ice‐free. Annual precipitation changes of ±20% would modify such estimated percentages of remaining ice by a factor of less than two.
A global OClO stratospheric layer discovered in GOMOS stellar occultation measurements
Authors: Fussen Didier , Vanhellemont Filip , Dodion Jan , Bingen Christine , Mateshvili Nina , Daerden Frank , Fonteyn Dominique , Errera Quentin , Chabrillat Simon , Kyrölä Erkki , Tamminen Johanna , Sofieva Viktoria , Hauchecorne Alain , Dalaudier Francis , Bertaux Jean‐Loup , Renard Jean‐Baptiste , Fraisse Renaud , d'Andon Odile Fanton , Barrot Gilbert , Guirlet Marielle , Mangin Antoine , Fehr Thorsten , Snoeij Paul , Saavedra Lidia
Published: July 2006

The stratospheric ozone depletion observed in polar regions is caused by several catalytic cycles induced by reactive chlorine and bromine species. By reacting with BrO, ClO causes the formation of OClO which is considered as a proxy of the halogen activation. We present the first global determination of the stratospheric OClO distribution measured during the year 2003 by the stellar occultation spectrometer GOMOS. Besides its expected polar abundance, we discovered the presence of a worldwide OClO layer in the upper stratosphere. At lower altitudes, OClO seems also to be present beyond the limit of the polar vortices, an unreported feature.
Caliche as a geological repository for atmospheric sulfate
Authors: Howell Katie J. , Bao Huiming
Published: July 2006

Recent studies demonstrate that important information on sulfur source, oxidation pathway, transport pattern, and reaction kinetics of atmospheric oxidation of sulfur gases can be uncovered by measuring multiple isotope compositions of the oxidation product — secondary atmospheric sulfate (SAS). SAS from Earth's distant past, however, is rarely preserved in the rock records because of its high solubility and small quantity. We report here from the measurement of 47 modern and fossil caliche samples that caliches contain variable amounts of carbonate‐associated sulfate (CAS), and the Δ17O values of the CAS range from −0.12 to +2.32‰ with most values higher than the background value of −0.05‰ for seawater sulfate, indicating the presence of an SAS component derived from the oxidation of sulfur gases by atmospheric ozone or related oxidants. This study demonstrates that caliche, a pedogenic carbonate common in the geologic record, could serve as a repository for ancient SAS.
Growth differentiation factor 11 signals through the transforming growth factor‐β receptor ALK5 to regionalize the anterior–posterior axis
Authors: Andersson Olov , Reissmann Eva , Ibáñez Carlos F
Published: July 2006

Growth differentiation factor 11 (GDF11) contributes to regionalize the mouse embryo along its anterior–posterior axis by regulating the expression of Hox genes. The identity of the receptors that mediate GDF11 signalling during embryogenesis remains unclear. Here, we show that GDF11 can interact with type I receptors ALK4, ALK5 and ALK7, but predominantly uses ALK4 and ALK5 to activate a Smad3‐dependent reporter gene. Alk5 mutant embryos showed malformations in anterior–posterior patterning, including the lack of expression of the posterior determinant Hoxc10, that resemble defects found in Gdf11‐null mutants. A heterozygous mutation in Alk5, but not in Alk4 or Alk7, potentiated Gdf11−/−‐like phenotypes in vertebral, kidney and palate development in an Acvr2b−/− background, indicating a genetic interaction between the two receptor genes. Thus, the transforming growth factor‐β (TGF‐β) receptor ALK5, which until now has only been associated with the biological functions of TGF‐β1 to TGF‐β3 proteins, mediates GDF11 signalling during embryogenesis.
The microstructure and stability of Al∕AlN multilayered films
Authors: Xiao X. L. , McCulloch D. G. , McKenzie D. R. , Bilek M. M. M.
Published: July 2006

Al ∕ Al N multilayers with bilayer thicknesses ranging from 10to50nm were fabricated using a filtered cathodic arc deposition system. The effects on the microstructure of using two different deposition rates and applying an 8kV pulsed voltage (plasma immersion ion implantation or PIII) to the substrate were explored. The microstructure was found to undergo a transition in which the Al transformed from layers to an aggregated phase under some conditions. This behavior is explained by a model in which the aggregation process is limited by diffusion. High deposition rates and the application of PIII were both found to encourage the transition by increasing diffusion. The model defines a phase diagram which predicts whether a multilayer or an aggregated structure will occur. A maximum in intrinsic stress was found to occur when the average feature size was 15nm for both layers and aggregates.
Magnetic-field-induced crystallographic texture enhancement in cold-deformed FePt nanostructured magnets
Authors: Cui B. Z. , Han K. , Li D. S. , Garmestani H. , Liu J. P. , Dempsey N. M. , Schneider-Muntau H. J.
Published: July 2006

This paper reports a unique approach to the fabrication of magnetically anisotropic nanostructured FePt magnets: cyclic sheath cold rolling and subsequent magnetic annealing. High magnetic fields enhance both crystallographic texture and magnetic properties of cold-deformed FePt nanostructured magnets. Magnetic annealing increases (001) out-of-plane texture of the FePt hard phase by 50% and introduces magnetic anisotropy in the annealed samples. It is suggested that pretextured Fe and Pt nanocrystals provide favorable nucleation sites for magnetic-field-induced nucleation and growth of textured FePt grains. It is argued that the enhancement of texture of the FePt hard phase and promotion of the solid-state phase transformation by magnetic annealing are the reasons for improvement of the magnetic properties.
Temperature and pressure dependences of the copper-related green emission in ZnO microrods
Authors: Su F. H. , Liu Y. F. , Chen W. , Wang W. J. , Ding K. , Li G. H. , Joly A. G. , McCready D. E.
Published: July 2006

We have investigated the temperature and pressure dependences of the copper-related green emission, which show fine structure at low temperature, from tetrapodlike ZnO microrods. The temperature dependence of the green emission energy follows the changes in the band gap from 10–200K, but deviates from this behavior above 200K. The pressure dependence of the copper-related green band (25±5meV∕GPa) is similar to that of the band gap of ZnO, and is larger than that reported previously for defect-related green emission in ZnO.
Estimation of electron temperature in transient glow discharge using ionization wave
Authors: Hoshi Y. , Yokota A. , Yoshida H. , Akedo J.
Published: July 2006

Through ionization waves (striation), the transition of glow discharge to arc discharge was observed and relevant electron temperatures were determined experimentally. The velocity of ionization waves in a cathode flare increased from twofold to threefold that in an anode flare. It was assumed that the electron temperature of an anode flare was 4.0-fold to 8.4-fold higher than that in a dark space, and the typical electron temperatures in a dark space and an anode flare were 1.8×103 and 1.0×104K, respectively. The electron temperature of the anode flare agreed well with the theoretical value of a positive column in steady glow discharge.
Optical properties of low-strained InxGa1−xAs∕GaAs quantum dot structures at the two-dimensional–three-dimensional growth transition
Authors: Poloczek P. , Sęk G. , Misiewicz J. , Löffler A , Reithmaier J. P. , Forchel A.
Published: July 2006

In x Ga 1 − x As ∕ Ga As quantum dots (QDs) were grown by solid source molecular beam epitaxy for indium contents of around 30%, which assures the QD growth in the very low strain limit. The structures were fabricated for a constant nominal InxGa1−xAs layer thickness but varying content (strain) from below to far above the critical thickness conditions, which has allowed to detect the onset of three-dimensional island formation and their evolution with the increasing material amount (for higher In contents the critical thickness for island formation is smaller and hence a larger fraction of the InxGa1−xAs layer is spent on dot formation). In order to investigate the properties of such an uncommon QD system, photoreflectance and photoluminescence, combined with scanning electron microscopy, have been used. Optical transitions connected with the ternary layer have been observed and followed from the lowest content quantum well case through the transformation into three-dimensional islands on the wetting layer (WL) and a coexistence of the QD-related and WL-related transitions. Due to the observation of both heavy hole and light hole related transitions in photoreflectance spectra, the thickness of the wetting layer versus changed indium content could be determined, comparing the experimental data with the results of the effective mass envelope function calculations.
X-ray absorption spectroscopy study of FePt thin films
Authors: Martins A. , Souza-Neto N. M. , Fantini M. C. A. , Santos A. D. , Prado R. J. , Ramos A. Y.
Published: July 2006

Equiatomic FePt thin films with fcc or L10 structure were studied by x-ray-absorption spectroscopy. The extended x-ray-absorption fine structure and x-ray-absorption near edge structure analysis, sensitive to the local structure and chemical order, show the formation of a Fe-rich neighborhood around Fe, indicating segregation of atomic species inside the film, and not a random distribution, as pointed out in the literature. The polarization dependence of the extended x-ray-absorption fine structure signal reveals and quantifies the different chemical and local order inside the samples, for both kinds of structure. The results are correlated with the long-range structural order measured by x-ray diffraction and magnetic properties of the material.
Luminescence induced by high-velocity impacts of metallic particles on metal surfaces
Authors: Klinkov Konstantin V. , Rein Martin
Published: July 2006

On impact of metallic particles on a metal surface light can be emitted from the region of impact. This phenomenon is studied experimentally for impact conditions that are typical of the cold spray deposition process, i.e., particle diameters and velocities are of the order of 10−5m and 500m∕s, respectively. The characteristics of impact-induced luminescence are analyzed. It is found that the intensity of luminescence depends not only on the energy of the impinging particles and on the stresses produced on impact but also on the particular combination of materials of the particles and the plate. Possible sources of luminescence are discussed.
Zone center optical phonons in AlxGa1−xN mixed crystals
Authors: Kazan M. , Masri P. , Sumiya M.
Published: July 2006

Infrared reflectivity and Raman spectroscopy were used as two complementary experiments to probe the zone center optical phonons in the aluminum gallium nitride (AlxGa1−xN) systems. A careful analysis of the infrared reflectivity data using the Kramers-Kronig technique and classical dispersion theory gives several resonance modes shifting in frequency with the mole fraction of the aluminum content in the alloy. A signature of an additional resonance mode appears for x∼0.58. A geometrical arrangement was performed to observe the E2 and A1(LO) phonons from the first order Raman scattering. The variation of the frequencies of these phonons was followed in the compositional range investigated. In addition to these two phonons observed from the Raman scattering, a new phonon mode shows up for x∼0.4. Our experimental results were compared with a theoretical study of the lattice dynamics of random AlxGa1−xN alloy based on the generalization of the modified random-element isodisplacement and rigid-ion model in order to interpret the experimentally observed resonance modes. The two-mode behavior in the AlxGa1−xN alloy was observed only for the E1(TO) optical mode.
An enhancement-mode GaAs heterojunction transistor using benzocyclobutene as gate dielectric
Authors: Jones G. M. , Hu B. H. , Yang C. H. , Yang M. J. , Reno J. L.
Published: July 2006

We propose and demonstrate an enhancement-mode AlxGa1−xAs∕GaAs single heterojunction field-effect transistor, in which the gate dielectric consists of an epitaxial AlxGa1−xAs layer and spin-on benzocyclobutene. The as-grown sample is undoped and, as a result, nonconductive at 4.2K. However, under a positive gate bias, high mobility two-dimensional electrons at the heterointerface are induced, as evidenced by magnetotransport characteristics. Numerical simulations of a model structure provide insight into applications in mesoscopic devices.
Photoreflectance investigations of quantum well intermixing processes in compressively strained InGaAsP∕InGaAsP quantum well laser structures emitting at 1.55μm
Authors: Podhorodecki A. , Andrzejewski J. , Kudrawiec R. , Misiewicz J. , Wojcik J. , Robinson B. J. , Roschuk T. , Thompson D. A. , Mascher P.
Published: July 2006

We have investigated the effects of interdiffusion and its technological parameters on the subband structure in compressively strained InGaAsP quantum wells (QWs) using photoreflectance and photoluminescence techniques. p-i-n laser structures with three QWs were grown by gas source molecular beam epitaxy and capped with dielectric films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition and annealed using a rapid thermal annealing process. A numerical real-time wave-packet propagation method including static electric field, strain in the wells and barriers, and error function interface diffusion modeling is used to calculate the transition energies for the diffused QWs. It has been shown that the shift of the energy levels due to the interdiffusion related changes of the well confinement potential profile is a consequence of two competing processes: a change of the well width and an effective increase of the band gap energy resulting in a net blueshift of all optical transitions. Moreover, it has been found that quantum well intermixing does not significantly influence the built-in electric fields distribution.
The role of molar conductivity in electrospray cone-jet mode current scaling
Authors: Smith Katharine L. , Alexander Matthew S. , Stark John P. W.
Published: July 2006

A high accuracy online flow rate measurement system has been used to determine the current flow rate scaling relationships for solutions of organic solvents doped with sodium iodide and for the ionic liquid 1-ethyl-3-methyl imidazolium tetrafluoroborate over a range of conductivities from 0.0025−1.3S∕m. The current flow rate trends for these solutions were found to exhibit a power law relationship similar to that described by previous researchers, where I (the electrospray current) is proportional to Q (the volumetric flow rate) to some power n. However, the exponent n of the current flow rate trends was found to differ from the theoretical predictions reported in the literature. A study including data from literature revealed the exponent of the current flow rate trends to be sensitive to the molar conductivity of the sprayed solution.
Augmentation of macromolecular adsorption rates through transverse electric fields generated across patterned walls of a microfluidic channel
Authors: Das Siddhartha , Chakraborty Suman
Published: July 2006

The present study aims to establish a theoretical proposition that the rate of macromolecular adsorption can be augmented with application of transverse electric fields across patterned walls of a microfluidic channel. First, an approximate fully developed velocity profile is derived, which is subsequently utilized to solve the species conservation equation pertaining to a combined advection-diffusion transport. Closed form solutions for the concentration field are subsequently obtained, in consistency with the typical second order kinetics of macromolecular adsorption. It is suggested that the transverse electric field and pattern angles can be regulated as independent parameters to maximize the rate of macromolecular adsorption under the prevailing conditions.
Determination of vortex chirality using planar Hall effect
Authors: Huang Y. S. , Wang C. C. , Adeyeye A. O.
Published: July 2006

A simple method for determining the chirality of magnetization vortex in Co dots based on planar Hall effect (PHE) has been demonstrated. We detected different PHE signals associated with the direction of vortex propagation for magnetization vortices with opposite chiralities when a Co dot of diameter d=1μm and thickness t=40nm was placed off the center of a Hall junction. We observed that the magnitude of the voltage jump at the annihilation field is directly related to the chirality of the vortex. Our experimental results are in good agreement with a simple theoretical modeling using finite element analysis. The simulation shows ∼10% relative voltage change between vortices of opposite chiralities for d=1μm and ∼200% relative voltage change for d=150nm.
Structural and compositional analyses of a strained AlGaN∕GaN superlattice
Authors: Shiojiri M. , Čeh M. , Šturm S. , Chuo C. C. , Hsu J. T. , Yang J. R. , Saijo H.
Published: July 2006

We investigated the nanostructure of AlGaN∕GaN strained-layer superlattice (SLS) cladding in a GaN-based violet laser diode (LD) using a scanning-transmission electron microscope (STEM). Metal-organic vapor-phase epitaxy was used to grow 200 pairs of n-Al0.14Ga0.86N∕n-GaN layers directly on the n-GaN:Si contact layer that was deposited on a (0001) sapphire substrate. The Al0.14Ga0.86N and GaN layers were distinguished as dark and bright bands in the high-angle annular dark-field (HAADF) images taken in the [1¯21¯0] zone axis. The widths of the Al0.14Ga0.86N and GaN layers were determined to be 2.24±0.09 and 2.34±0.15nm, respectively. The lattice parameters of the Al0.14Ga0.86N were measured to be a=0.32±0.01nm and c=0.50±0.02nm, and those of the GaN, a=0.32±0.02nm and c=0.52±0.03nm. This is a direct illustration of the SLSs, where a good lattice matching in the basal plane caused by shrinkage of the Al0.14Ga0.86N lattice normal to the basal plane suppresses the generation of misfit dislocations. Dislocations, appearing as dark contours in bright-field STEM images and as bright contours in HAADF images, run either parallel or perpendicular to the c direction. Another mechanism of the SLS to suppress lattice defects in the LDs has also been disclosed.
Synthesis, characterizations, and field emission studies of crystalline Na2V6O16 nanobelt paper
Authors: Lim S. H. , Lin J. Y. , Zhu Y. W. , Sow C. H. , Ji W.
Published: July 2006

Crystalline Na2V6O16∙3H2O nanobelts have been synthesized by refluxing V2O5 and NaF and self-weaved into a sheet of paper via a vacuum filtration process. Scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy were used to characterize the morphology, structure, and chemical composition of the nanobelt papers. The dehydrated Na2V6O16 nanobelts are excellent field emission candidates, with a low turn-on field of 6.8V∕μm, a large current density up to 2.5mA∕cm2 at an electric field of 10V∕μm, and a very uniform distribution of emission sites.
Anisotropic photonic gratings formed in photocross-linkable polymer liquid crystals
Authors: Ono Hiroshi , Emoto Akira , Kawatsuki Nobuhiro
Published: July 2006

We demonstrated anisotropic photonic gratings in photocross-linkable polymer liquid crystals irradiated with three mutually coherent beams. Both birefringence and surface relief modulation were induced by reorientation and/or migration of mesogenic molecules. Anisotropy and optical properties of photonic gratings were strongly dependent on the combination of polarization states of the three beams. Atomic force microscopy revealed that topological patterns of gratings formed according to interference patterns of the three beams and diffraction efficiencies of recorded gratings depended on polarization direction of the linearly polarized probe beam. These diffraction properties including efficiency and optical anisotropy could be explained by the theory based on Jones calculus.
Deterministic nanoassembly: Neutral or plasma route?
Authors: Levchenko I. , Ostrikov K. , Keidar M. , Xu S.
Published: July 2006

It is shown that, owing to selective delivery of ionic and neutral building blocks directly from the ionized gas phase and via surface migration, plasma environments offer a better deal of deterministic synthesis of ordered nanoassemblies compared to thermal chemical vapor deposition. The results of hybrid Monte Carlo (gas phase) and adatom self-organization (surface) simulation suggest that higher aspect ratios and better size and pattern uniformity of carbon nanotip microemitters can be achieved via the plasma route.
Anomalous attenuation of the positive temperature coefficient of resistivity in a carbon-black-filled polymer composite with electrically conductivein situmicrofibrils
Authors: Xu Xiang-Bin , Li Zhong-Ming , Dai Kun , Yang Ming-Bo
Published: July 2006

The positive temperature coefficient of resistivity (PTCR) of in situ microfibrillar carbon black∕poly (ethylene terephthalate)∕polyethylene composite attenuates dramatically after a sufficient time of isothermal treatment without oxygen above the melting region of polyethylene. The inhomogeneous surface microstructure and the large size of the microfibrils are the key factors controlling PTCR attenuation, through which a model is proposed to explain this anomalous phenomenon. An effective approach is accordingly developed to prepare recyclable semicrystalline thermoplastic based electrically conductive polymer composite with steady conductivity in wide temperature range.
Ionization spectra and electronic decay in small iodide clusters: Fully relativistic results
Authors: Pernpointner Markus , Knecht Stefan , Cederbaum Lorenz S.
Published: July 2006

Singly ionized systems in high-lying energetic final states can stabilize themselves via various electronic decay mechanisms. With increasing system size interatomic and intermolecular processes dominate over intra-atomic (Auger) decay channels. For the small (HI)2 and (LiI)2 clusters fully relativistic ionization spectra are calculated and the subsequent electronic decay of the cations is investigated. Due to the presence of the iodine atom a fully relativistic description is mandatory and was performed by the algebraic diagrammatic construction technique in its four-component form. The lifetimes of the singly ionized final states are estimated by the application of Weisskopf-Wigner [Z. Phys. 63, 54 (1930)] theory.
Epitaxial∕amorphous Ba0.3Sr0.7TiO3 film composite structure for tunable applications
Authors: Yamada Tomoaki , Sherman Vladimir O. , Nöth Andreas , Muralt Paul , Tagantsev Alexander K. , Setter Nava
Published: July 2006

A Ba0.3Sr0.7TiO3 (BST) thin film composite structure was fabricated by means of a selective epitaxial growth process. The epitaxial growth of BST on SrRuO3 electrode surface was selectively achieved at 485°C using a prepatterned ultrathin amorphous BST layer that locally prevented crystallization. This self-buildup mechanism resulted in a columnar composite structure, where epitaxial and amorphous BST columns are electrically connected in parallel. The effective permittivity of the composite capacitors decreased linearly upon increasing the amorphous BST concentration, while the tunability stayed fairly unchanged until it reached 70%. The results agree with the theoretical ferroelectric∕dielectric parallel composite model.
Whole plant response of crop and weed species to high subsoil boron
Authors: Choi Eun-Young , McNeill Ann , Coventry David , Stangoulis James
Published: July 2006

Within the semi-arid region of south-eastern Australia, high levels of subsoil boron (B) in alkaline soil can limit production of dryland crops. The aim of this research was to investigate the whole plant response to a range of subsoil-extractable B concentrations for a number of crop and weed species common to agricultural areas of South Australia. Specifically, the objectives were to determine (a) the morphological response of the entire root system to high subsoil B and (b) the available B concentrations in subsoil critical for expression of shoot traits commonly used in selection of B tolerance. Barley grass (Hordeum glaucum L.), crop barley (Hordeum vulgare) variety Clipper and breeders’ line VB9953, fababean (Vicia faba var. Fjiord), Lincoln weed (Diplotaxis tenuifolia L.), prickly lettuce (Lactuca serriola), and evening primrose (Oenothera stricta L.) were grown in sealed PVC cylinders (500 mm deep by 150 mm diam.) containing a sandy soil. The concentration of extractable B in the topsoil (0–0.20 m), considered non-toxic, was 0.5 mg/kg for all cylinders but a range of B treatments (0.5, 2.4, 4.3, 6.8, or 12.2 mg/kg) was applied directly to the subsoil (0.30–0.50 m). Increasing the concentration of extractable B in the subsoil decreased root dry weight in this region, but did not reduce water use from subsoil by barley grass or evening primrose. The response of the roots in the topsoil and subsequent responses in the shoot also differed among species. Symptoms of B toxicity in shoots of all the species were observed at subsoil-extractable B concentrations of 12.2 mg/kg and at lower concentrations in some of the crop and weed species. Shoot growth, total water use, and root growth in topsoil of Clipper and Lincoln weed were severely impaired by high subsoil-extractable B, as was topsoil root growth in evening primrose, with the reduction in the weed species being mostly associated with a decrease in taproot dry weight. Barley grass, VB9953, evening primrose, and to a lesser extent fababean and prickly lettuce, maintained shoot growth at all subsoil-extractable B concentrations, despite a reduction in subsoil water use by VB9953. Prickly lettuce and VB9953 also sustained root growth in the topsoil whilst fababean and barley grass increased root growth in the topsoil in response to high subsoil extractable B. There was no direct relationship between the quantity of B accumulated in shoots and detrimental effects on growth. Furthermore, there appeared to be no direct relationship between water uptake and B uptake since irrespective of the effect of subsoil B on either subsoil or total water use, shoot B concentration increased in all the species/genotypes as subsoil B increased. The degree to which plants were deemed to exhibit tolerance was, therefore, highly dependent upon the trait used for assessment. One suggestion in the current study is that shoot dry matter in B toxic soil can be a consistent parameter for considering varieties for tolerance to B toxicity.
Pattern analysis on protein properties of Chinese and CIMMYT spring wheat cultivars sown in China and CIMMYT
Authors: Zhang Yong , He Zhonghu , Zhang Aimin , van Ginkel Maarten , Peña Roberto J. , Ye Guoyou
Published: July 2006

Improvement of processing quality is a very important objective for Chinese wheat breeding programs. Twenty-five CIMMYT and Chinese spring wheat cultivars were grown at four managed conditions by CIMMYT in Cd. Obregon, Sonora, Mexico and in nine environments in China, over two successive wheat seasons from 2000 to 2002. These trials were used to identify patterns of cultivar, environment and cultivar × environment interactions, and to determine opportunities for indirect selection for protein content and the protein-quality related parameter, SDS sedimentation (SDSS) value. The cultivar Inqalab 91 showed low levels of interaction with environments in the 2000–01 crop cycle for protein content, and expressed intermediate levels for both protein content and SDSS value, across most of the environments in both years. Longmai 26 had consistently high protein content and SDSS value across environments in both years, indicating that it is possible to breed cultivars expressing high yields with good protein properties. Cluster analyses revealed that cultivars grouped differently for protein content and SDSS value. Besides photoperiod, water availability appeared to influence the ranking of cultivars for protein content and SDSS value. Temperature and soil type may underlie the observed interactions for protein content, while temperature may also be a factor associated with interactions for SDSS value. The full irrigation managed environment in Mexico, with the cultivars sown on raised beds two months later than optimum and exposing them to late heat, clustered together with the Chinese environments Huhhot, Yongning, and Hejin in the 2000–01 season for SDSS value. This indicates that there is an opportunity to exploit indirect responses to selection in the CIMMYT management environments for SDSS value with relevance for China’s spring wheat regions. However, there seemed little chance for positive indirect selection in CIMMYT’s managed environments for China in regard to protein content, as environments clustered distinctly. Pattern analyses permitted a sensible and useful summary for this multi environment experiment, helping in understanding natural relationships and variations in cultivar performance among the various environment groups, and assisting in the structuring of environments.
A stable isotope aridity index for terrestrial environments
Authors: Levin Naomi E. , Cerling Thure E. , Passey Benjamin H. , Harris John M. , Ehleringer James R.
Published: July 2006

We use the oxygen isotopic composition of tooth enamel from multiple mammalian taxa across eastern Africa to present a proxy for aridity. Here we report tooth enamel δ
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O values of 14 species from 18 locations and classify them according to their isotopic sensitivity to environmental aridity. The species are placed into two groups, evaporation sensitive (ES) and evaporation insensitive (EI). Tooth enamel δ
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O values of ES animals increase with aridity, whereas the tooth enamel δ
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O values of EI animals track local meteoric water δ
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O values, demonstrating that bioapatite δ
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O values of animals with different behaviors and physiologies record different aspects of the same environment. The enrichment between tooth enamel δ
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O values of ES and EI animals records the degree of
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O enrichment between evaporated water (ingested water or body water) and source water, which increases with environmental aridity. Recognition of the ES–EI distinction creates the opportunity to use the
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O composition of bioapatite as an index of terrestrial aridity.
Critical Pathways in Heart Function: Bis(2-chloroethoxy)methane-Induced Heart Gene Transcript Change in F344 Rats
Authors: Dunnick J. , Blackshear P. , Kissling G. , Cunningham M. , Parker J. , Nyska A.
Published: July 2006

Gene transcript changes after exposure to the heart toxin, bis(2-chloroethoxy)methane (CEM), were analyzed to elucidate mechanisms in cardiotoxicity and recovery. CEM was administered to 5-week-old male F344/N rats at 0, 200, 400, or 600 mg/kg by dermal exposure, 5 days per week, for a total of 12 doses by study day 16. Heart toxicity occurred after 2 days of dosing in all 3 regions of the heart (atrium, ventricle, interventricular septum) and was characterized by myofiber vacuolation, necrosis, mononuclear-cell infiltration, and atrial thrombosis. Ultrastructural analysis revealed that the primary site of damage was the mitochondrion. By day 5, even though dosing was continued, the toxic lesions in the heart began to resolve, and by study day 16, the heart appeared histologically normal. RNA was extracted from whole hearts after 2 or 5 days of CEM dosing. After a screen for transcript change by microarray analysis, dose-response trends for selected transcripts were analyzed by qRT-PCR. The selected transcripts code for proteins involved in energy production, control of calcium levels, and maintenance of heart function. The down-regulation of ATP subunit transcripts (Atp5j, ATP5k), which reside in the mitochondrial membranes, indicated a decrease in energy supply at day 2 and day 5. This was accompanied by down-regulation of transcripts involved in high-energy consumption processes such as membrane transport and ion channel transcripts (e.g., abc1a, kcnj12). The up-regulation of transcripts encoding for temperature regulation and calcium binding proteins (ucp1 and calb3) only at the 2 low exposure levels, suggest that these adaptive processes cannot occur in association with severe cardiotoxicity as seen in hearts at the high exposure level. Transcript expression changes occurred within 2 days of CEM exposure, and were dose- and time-dependent. The heart transcript changes suggest that CEM cardiotoxicity activates protective processes associated energy conservation and maintenance of heart function.
Welding Fume Exposure and Associated Inflammatory and Hyperplastic Changes in the Lungs of Tumor Susceptible A/J Mice
Authors: Solano-Lopez Claudia , Zeidler-Erdely Patti C. , Hubbs Ann F. , Reynolds Steven H. , Roberts Jenny R. , Taylor Michael D. , Young Shih-Houng , Castranova Vincent , Antonini James M.
Published: July 2006

It has been suggested that welding fume (WF) exposure increases lung cancer risk in welders. Epidemiology studies have failed to conclude that WF alone causes lung cancer and animal studies are lacking. We examined the course of inflammation, damage, and repair in the lungs of A/J mice, a lung tumor susceptible strain, caused by stainless steel WF. Mice were exposed by pharyngeal aspiration to 40 mg/kg of WF, silica, or saline. Bronchoalveolar lavage (BAL) was performed 24 hours, 1 and 16 weeks to assess lung injury and inflammation and histopathology was done 1, 8, 16, 24, and 48 weeks postexposure. Both exposures increased inflammatory cells, lactate dehydrogenase and albumin at 24 hr and 1 week. At 16 weeks, these parameters remained elevated in silica-exposed but not WF-exposed mice. Histopathologic evaluation at 1 week indicated that WF induced bronchiolar epithelial hyperplasia with associated cellular atypia, alveolar bronchiolo-alveolar hyperplasia (BAH) in peribronchiolar alveoli, and peribronchiolar lymphogranulomatous inflammation. Persistent changes included foci of histiocytic inflammation, fibrosis, atypical bronchiolar epithelial cells, and bronchiolar BAH. The principle changes in silica-exposed mice were histiocytic and suppurative inflammation, fibrosis, and alveolar BAH. Our findings that WF causes persistent bronchiolar and peribronchiolar epithelial changes, suggest a need for studies of bronchiolar changes after WF exposure.
Programme factors that influence completion of residential treatment
Authors: MEIER PETRA S. , BEST DAVID
Published: July 2006

The aim of this study was to predict retention in residential rehabilitation (RR) services for drug users, focusing on service provider factors. A national postal survey of RR services in England and Wales was carried out and information was obtained from 57 of 87 services identified (65.5%). Service managers were asked to complete a questionnaire asking about treatment philosophy, treatments provided, staff characteristics and staffing levels, as well as overall service size and funding. Services also provided information on the number of clients admitted and the number who had completed, dropped out and been asked to leave in the past year. Completion rates varied widely, from 3% to 92%, with an average of 48%. Higher completion rates were associated with lower counsellor caseloads, fewer beds, single rooms, shorter scheduled treatment durations, higher fees per client and provision of what could be termed a balanced treatment programme containing adequate amounts of individual counselling and programme‐free time, and with only moderate demands for domestic duties. Programmes with more drug than alcohol users had lower completion rates, but the proportion of dual diagnosis or criminal justice referred clients did not appear to affect retention. Completion rates varied as a function of a number of service factors that are amenable to manipulation. To retain clients successfully, programmes should not be too large and should have adequate levels of therapeutic staff, a well‐developed treatment schedule which is not too demanding for the client in terms of duties or overall time spent in structured activities, and which incorporates sufficient levels of individual counselling.