bluuebunny/crossref_metadata_2025 huggingface dataset:
Very high resolution seismic profiling at the Brazil Margin
Authors: Murdmaa I. O. , Borisov D. G. , Demidova T. A. , Ivanova E. V. , Levchenko O. V. , Marinova Y. G. , Mutovkin A. D. , Putans V. A. , Humbs Peter , Skolotnev S. G. , Peyve A. A.
Published: June 2012

Acoustically stratified seismic images are widely used in studies of sedimentation mechanisms producing thick sedimentary aprons on continental rises. However, insuffcient vertical resolution of seismic records commonly restricts a more detailed interpretation of individual reflectors within accumulations to reconstruct specifc short‐term sedimentological events. (Reflectors correspond to boundaries between sedimentary layers with different acoustic properties and are imaged in seismic records as continuous lines.) Very high resolution (VHR) seismic profiling conducted during Cruise 33 of the Russian research vessel Akademik Ioffe (2011) provided correlation of acoustic reflectors, distanced from one another by less than 50 centimeters, with thin sedimentary layers recovered by gravity cores.
Small unmanned aircraft systems for remote sensing and Earth science research
Authors: Hugenholtz Chris H. , Moorman Brian J. , Riddell Kevin , Whitehead Ken
Published: June 2012

To understand and predict Earth‐surface dynamics, scientists often rely on access to the latest remote sensing data. Over the past several decades, considerable progress has been made in the development of specialized Earth observation sensors for measuring a wide range of processes and features. Comparatively little progress has been made, however, in the development of new platforms upon which these sensors can be deployed. Conventional platforms are still almost exclusively restricted to piloted aircraft and satellites. For many Earth science research questions and applications these platforms do not yet have the resolution or operational flexibility to provide answers affordably. The most effective remote sensing data match the spatiotemporal scale of the process or feature of interest. An emerging technology comprising unmanned aircraft systems (UAS), also known as unmanned aerial vehicles (UAV), is poised to offer a viable alternative to conventional platforms for acquiring high‐resolution remote sensing data with increased operational flexibility, lower cost, and greater versatility (Figure 1).
Perron receives 2011 Luna B. Leopold Young Scientist Award: Response
Authors: Perron J. Taylor
Published: June 2012

J. Taylor Perron received the 2011 Luna B. Leopold Young Scientist Award at the 2011 AGU Fall Meeting, held 5–9 December in San Francisco, Calif. The award recognizes “a young scientist for making a significant and outstanding contribution that advances the field of Earth and planetary surface processes.”
Mercurial magnetic field waves measured by orbiting satellite
Authors: Schultz Colin
Published: June 2012

Researchers working with NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging ( MESSENGER) spacecraft report the frequent detections of Kelvin‐Helmholtz (KH) waves at the edge of the innermost planet's magnetosphere. In six different sets of magnetic field measurements made by the orbiter as it passed through Mercury's magnetopause, the boundary that separates the planet's magnetosphere from the solar wind plasma in the magnetosheath, Sundberg et al. detected the magnetic field oscillations characteristic of fully developed KH waves. These waves form when fuids of different speeds travel alongside each other—in this case, the magnetosphere and magnetosheath plasmas—and promote mixing of the plasmas on larger spatial, and shorter time, scales than diffusive transport. The observations, which span the frst 88 days of MESSENGER's time in orbit, bring Mercury alongside Earth, Saturn, and Venus as planets for which such KH waves are of importance.
How earthquake properties vary with depth
Authors: Balcerak Ernie
Published: June 2012

A new study shows systematically how seismic properties vary with depth. Lay et al. analyzed recent large and great earthquakes, including the 2004 Sumatra‐Andaman (Mw 9.2), 2010 Chile (Mw 8.8), and 2011 Tohoku (Mw 9.0) earthquakes. The researchers define four domains of seismogenic behavior along megathrust faults according to depth. In domain A, the shallowest, reaching to about 15 kilometers below sea level, large tsunami‐ generating earthquakes can occur. In domain B, extending from about 15‐ to 35‐kilometers depth, great earthquake events with large slip but diffuse short‐period energy occur. In domain C, from 35‐ to 55‐kilometers depth, smaller isolated megathrust patches rupture, producing bursts of coherent short‐period energy in both great ruptures and in moderatesized events. In domain D, which extends from about 30‐ to 45‐kilometers depth in subduction zones where relatively young ocean lithosphere is being underthrust with shallow plate dip, low‐frequency earthquakes, seismic tremor, and slow slip events occur. Below this zone, stabile sliding or ductile doma takes place. (Journal of Geophysical Research‐Solid Earth, doi:10.1029/2011JB009133, 2012)
What drives knickpoints to migrate upstream?
Authors: Kumar Mohi
Published: June 2012

Mountain landscapes are shaped by tectonic uplift, which creates topography, and climate, which determines the rate at which erosion wears down upland areas. Networks of rivers and streams transmit both tectonic and climate signals to landscapes: On a fundamental level, their erosive power is determined by the mountain's steepness, a factor controlled by the rate of tectonic uplift, and the river discharge, a factor set by climate forces such as precipitation rates across an area. Whittaker and Boulton seek to answer the question of how exactly rivers and streams are affected by climate and tectonics. They focus on knickpoints, which they define as the precise location on a river‐long profile that plots channel elevation downstream distance, where the steepness of the stream bed changes most rapidly. Knickpoints migrate upstream depending on the flow of the river, the properties of the rock underlying it, and the degree to which rapid tectonic uplift causes the river to incise to keep pace with the rock uplift rate. But which of these factors dominate?
Climate‐induced change in biogenic bromine emissions from the Antarctic marine biosphere
Authors: Hughes Claire , Johnson Martin , von Glasow Roland , Chance Rosie , Atkinson Helen , Souster Terri , Lee Gareth A. , Clarke Andrew , Meredith Michael , Venables Hugh J. , Turner Suzanne M. , Malin Gill , Liss Peter S.
Published: June 2012

Climate change and human activities are expected to have a major impact on the structure and functioning of marine ecosystems and the biogeochemical cycles they mediate in the coming years. Here we describe time series measurements of biogenic bromocarbons (CHBr3 and CH2Br2) collected in coastal waters of the western Antarctic Peninsula which is one of the world's most rapidly changing marine environments. Our measurements spanned a period of changing sea‐ice dynamics and phytoplankton community structure driven by climatic forcing. Specifically, the occurrence of high chlorophylla concentrations (≥5 μg L−1) and dominance of the largest phytoplankton size fraction (≥20 μm) indicating diatom bloom conditions was reduced following winter periods with a relatively short winter sea‐ice duration (<50 days). While large inter‐annual variability in seawater CHBr3 concentrations was observed alongside these changes the same was not found for CH2Br2 which is surprising given their proposed common source. Seawater CHBr3 concentrations were found to be significantly higher (122 [14.7–580] pmol L−1, P < 0.0001, Mann‐Whitney) in samples collected in diatom bloom compared to non‐bloom waters (42.9 [12.0–126] pmol L−1). A comparison of sea‐to‐air flux rates suggests that a switch from diatom bloom to non‐bloom conditions results in a factor of 3–4 decrease in average CHBr3sea‐to‐air emission rates which will reduce the supply of biogenic bromine to the atmosphere. Our calculations suggest that this will drive a decrease in inorganic bromine levels in the troposphere by a factor of 2–3 outside of ozone depletion events with potentially important implications for ozone cycling and dimethyl sulphide oxidation. This work has captured and crucially quantified the impact of a climate‐induced change in a marine ecosystem on ocean‐atmosphere biogeochemistry.
Coccolithophore paleoproductivity and ecology response to deglacial and Holocene changes in the Azores Current System
Authors: Schwab C. , Kinkel H. , Weinelt M. , Repschläger J.
Published: June 2012

In order to test the sensitivity of marine primary productivity in the midlatitude open ocean North Atlantic to changes in the Atlantic Meridional Overturning Circulation (AMOC), we investigated two spliced sediment cores from a site south of the Azores Islands at the northern rim of the North Atlantic subtropical gyre. For this purpose we analyzed coccolithophore assemblages, diatom abundances, alkenones and conducted X‐ray fluorescence (XRF) core scanning. During times of reduced AMOC, especially during Heinrich event 1 (H1) and the Younger Dryas, we observe a strong increase in productivity as evidenced by high coccolith accumulation rates, high alkenone concentrations/accumulation rates, high Ba/Ti‐ratios, high abundances of diatoms and low abundances ofF. profunda. The increased productivity is partly caused by a more southern position of the Azores Front (AzF), and hence by a less northward extension of the subtropical gyre, as deduced from high abundances of the temperate coccolithophore species G. muellerae and low abundances of subtropical species (Oolithotus spp., Umbellosphaera spp., Umbilicosphaeraspp.). However, to explain the full range of the observed productivity increase, other factors like increased westerly winds and advection of nutrient‐rich surface waters have also to be considered. Because this pattern can also be observed in other sediment cores from the midlatitude North Atlantic, we propose that during times of reduced AMOC there has been a band of strongly increased productivity across the North Atlantic at the northern rim of the contracted subtropical gyre, which partly counteracts the decreased organic carbon pump in the high northern latitudes.
Composite adaptive fuzzy control for synchronizing generalized Lorenz systems
Authors: Pan Yongping , Er Meng Joo , Sun Tairen
Published: June 2012

This paper presents a methodology of asymptotically synchronizing two uncertain generalized Lorenz systems via a single continuous composite adaptive fuzzy controller (AFC). To facilitate controller design, the synchronization problem is transformed into the stabilization problem by feedback linearization. To achieve asymptotic tracking performance, a key property of the optimal fuzzy approximation error is exploited by the Mean Value Theorem. The composite AFC, which utilizes both tracking and modeling error feedbacks, is constructed by introducing a series-parallel identification model into an indirect AFC. It is proved that the closed-loop system achieves asymptotic stability under a sufficient gain condition. Furthermore, the proposed approach cannot only synchronize two different chaotic systems but also significantly reduce computational complexity and implemented cost. Simulation studies further demonstrate the effectiveness of the proposed approach.
Structured surfaces for enhanced pool boiling heat transfer
Authors: Chu Kuang-Han , Enright Ryan , Wang Evelyn N.
Published: June 2012

We experimentally investigated surface roughness-augmented wettability on critical heat flux (CHF) during pool boiling with horizontally oriented surfaces. Microstructured surfaces with a wide range of well-defined surface roughness were fabricated, and a maximum CHF of ∼208 W/cm2 was achieved with a surface roughness of ∼6. An analytical force-balance model was extended to explain the CHF enhancement. The excellent agreement found between the model and experimental data supports the idea that roughness-amplified capillary forces are responsible for the CHF enhancement on structured surfaces. The insights gained from this work suggest design guidelines for new surface technologies with high heat removal capability.
Semiconductor nanowires for highly sensitive, room-temperature detection of terahertz quantum cascade laser emission
Authors: Vitiello Miriam S. , Viti Leonardo , Romeo Lorenzo , Ercolani Daniele , Scalari G. , Faist J. , Beltram F. , Sorba L. , Tredicucci A.
Published: June 2012

We report on the development of nanowire-based field-effect transistors operating as high sensitivity terahertz (THz) detectors. By feeding the 1.5 THz radiation field of a quantum cascade laser (QCL) at the gate-source electrodes with a wide band dipole antenna, we record a photovoltage signal corresponding to responsivity values >10 V/W, with impressive noise equivalent power levels <6 × 10−11 W/√Hz at room temperature and a wide modulation bandwidth. The potential scalability to even higher frequencies and the technological feasibility of realizing multi-pixel arrays coupled with QCL sources make the proposed technology highly competitive for a future generation of THz detection systems.
High pressure Raman and x-ray diffraction studies on the decomposition of tungsten carbonyl
Authors: Garimella Subrahmanyam , Drozd Vadym , Durygin Andriy , Chen Jiuhua
Published: June 2012

Polycrystalline tungsten hexacarbonyl, W(CO)6, was studied using in situ Raman spectroscopy and synchrotron x-ray diffraction (XRD) at high pressures up to 60 GPa in a diamond anvil cell. High pressure causes collapse of the Oh molecular symmetry in W(CO)6 leading to decomposition of the carbonyl compound. The decomposed material has characteristic of δ(OCO), v(C=C), v(C=O), and adsorbed CO Raman features. High pressure XRD results showed the irreversible amorphization of tungsten hexacarbonyl. A solid state vibrational coupling mechanism is proposed to explain the formation of δ(OCO) units. Further, the high pressure Raman results of W, Mo, and Cr hexacarbonyls are compared and the breakdown of the Dewar-Chatt-Duncanson model in this family is qualitatively discussed.
High-pressure behavior of osmium: An analog for iron in Earth’s core
Authors: Godwal B. K. , Yan J. , Clark S. M. , Jeanloz R.
Published: June 2012

High-resolution x-ray diffraction with diamond-anvil cells, using argon as a quasi-hydrostatic pressure medium, documents the crystal structure and equation of state of osmium to over 60 GPa at room temperature. We find the zero-pressure bulk modulus in fair agreement with other experiments as well as with relativistic electronic band-structure calculations: Osmium is the densest but not the most incompressible element at ambient conditions. We also find no evidence for anomalies in the ratio of unit-cell parameters, c/a, or in the compressibility of osmium as a function of pressure. This is in agreement with other experiments and quantum mechanical calculations but disagrees with recent claims that the electronic structure and equation of state of osmium exhibit anomalies at pressures of ∼15-25 GPa; the discrepancies are may be due to the effects of texturing.
High P-T phase transitions and P-V-T equation of state of hafnium
Authors: Hrubiak Rostislav , Drozd Vadym , Karbasi Ali , Saxena Surendra K.
Published: June 2012

We measured the volume of hafnium at several pressures up to 67 GPa and at temperatures between 300 to 780 K using a resistively heated diamond anvil cell with synchrotron x-ray diffraction at the Advanced Photon Source. The measured data allows us to determine the P-V-T equation of state of hafnium. The previously described [Xia et al., Phys. Rev. B 42, 6736–6738 (1990)] phase transition from hcp (α) to simple hexagonal (ω) phase at 38 GPa at room temperature was not observed even up to 51 GPa. The ω phase was only observed at elevated temperatures. Our measurements have also improved the experimental constraint on the high P-T phase boundary between the ω phase and high pressure bcc (β) phase of hafnium. Isothermal room temperature bulk modulus and its pressure derivative for the α-phase of hafnium were measured to be B0 = 112.9 ± 0.5 GPa and B0′ = 3.29 ± 0.05, respectively. P-V-T data for the α-phase of hafnium was used to obtain a fit to a thermodynamic P-V-T equation of state based on model by Brosh et al. [CALPHAD 31, 173–185 (2007)].
Pressure effects on unoriented and oriented single-walled carbon nanotube films studied by infrared microscopy
Authors: Kuntscher C. A. , Abouelsayed A. , Thirunavukkuarasu K. , Hennrich F. , Iwasa Y.
Published: June 2012

We present the results of pressure-dependent infrared transmission measurements on films of oriented and unoriented single-walled carbon nanotubes. Up to the highest applied pressure (∼9 GPa), the optical response of the oriented single-walled carbon nanotube film is highly anisotropic, with strong absorption bands for the polarization of the radiation along the alignment direction due to optical transitions between the Van Hove singularities in the density of states. With increasing pressure, the optical transitions shift to smaller energies, with an anomaly in the pressure-induced shifts at 2–3 GPa related to the deformation of the nanotubes’ cross section. Weak signatures of a second anomaly are found at around 5–6 GPa, probably related to a more drastic deformation of the nanotubes. Different pressure transmitting media change the pressure-induced effects only quantitatively. The results for the oriented nanotube films are very similar to those for the unoriented ones.
Manganese borides synthesized at high pressure and high temperature
Authors: Meng Xiangxu , Bao Kuo , Zhu Pinwen , He Zhi , Tao Qiang , Li Junjun , Mao Zhenpeng , Cui Tian
Published: June 2012

We synthesized various kinds of manganese borides by liquid-solid reaction from manganese and amorphous boron powders at high pressure and high temperature. The mixed powders with various atomic ratio of boron to manganese, B/Mn = 0.6, 1.2, 2, 3, 4, 8, were treated at temperature 1100–1350 °C and pressure 4.8-5.5 GPa, for 10–285 min. Typical manganese borides such as Mn4B, Mn2B, MnB, Mn3B4, MnB2, MnB4, and MnBx were synthesized. MnB2 plays an important role in the reaction, which is the middle product and it changes to Mn3B4 and boron with increasing holding time at a mixed atomic ratio of B/Mn = 2 and MnB2 reacted with boron to MnB4 with increasing holding time at a mixed atomic ratio of B/Mn = 8. The preferred orientation of Mn3B4 was also obtained at a mixed atomic ratio B/Mn = 2 and whose growth is highly oriented. The crystalline phases MnB2, Mn3B4, MnB, and Mn2B were prepared with large excess boron content.
In-plane Cu–O bond distribution and charge inhomogeneity in La2−xSrxCuO4 as a function of doping
Authors: Saini N. L. , Oyanagi H. , Adachi T. , Noji T. , Sato H. , Koike Y.
Published: June 2012

We report in-plane Cu–O atomic displacements as a function of doping in the La2−xSrxCuO4 system, determined by polarized Cu K-edge extended x-ray absorption fine structure measurements. We find a wide distribution of the Cu–O bonds showing a single peak asymmetric function for the system at low doping, which gets two peak function for the underdoped and optimally doped superconducting phases before turning to a single peak function for the overdoped phase. The results provide a direct evidence of critical local lattice fluctuations for an optimum transition temperature in the superconducting phases hosting quantum stripes.
High pressure nano-tomography using an iterative method
Authors: Wang Junyue , Yang Wenge , Wang Steve , Xiao Xianghui , De Carlo Francesco , Liu Yijin , Mao Wendy L.
Published: June 2012

An iterative method has been developed to improve the quality of 3D tomography data with limited angular access. Within 10 iteration cycles, the reconstructed data error can be improved by an order of magnitude and reach below 1%. This algorithm was applied to high pressure tomography data collected in a panoramic diamond anvil cell with the transmission x-ray microscopy technique, in which only 135° of data can be obtained. We found that the volumes measured for a tin (Sn) particle across the β–Sn to body-centered-tetragonal (bct) high pressure phase transition match the equation of state for Sn determined by x-ray diffraction. This result demonstrates the exciting potential for a wide range of high pressure imaging studies which are now enabled by use of the iteration method to reconstruct 3D tomography data.
A non-statistical atomic model for beam emission and motional Stark effect diagnostics in fusion plasmas
Authors: Ralchenko Yu. , Marchuk O. , Biel W. , Schlummer T. , Schultz D. R. , Stambulchik E.
Published: June 2012

In this work we analyze magnetic sublevel populations in a neutral beam penetrating a fusion plasma. The collisional-radiative model NOMAD was extended to include magnetic parabolic sublevels with principal quantum numbers n ⩽ 10. The collisional parameters were calculated with the advanced atomic-orbital close coupling method and the Glauber approximation. The ionization by the induced electric field was also included in the model. The results of our calculations show significant deviations of the sublevel populations and, accordingly, line intensities of the σ and π components, from the statistical approximation. It is shown, for instance, that for a number of experimental conditions the total intensity of σ components is not equal to the total intensity of π components, which has a strong effect on determination of magnetic field and pitch angle in fusion devices. The results are presented for a wide range of plasma and beam parameters. The most significant deviations are observed for strong magnetic fields and high beam energies typical for the ITER plasma, where component intensity ratios may deviate by more than 20% from the statistical values.
Strain control of AlGaN/GaN high electron mobility transistor structures on silicon (111) by plasma assisted molecular beam epitaxy
Authors: Aidam Rolf , Diwo Elke , Rollbühler Nicola , Kirste Lutz , Benkhelifa Fouad
Published: June 2012

This paper reports on the use of plasma assisted molecular beam epitaxy of AlGaN/GaN-based high electron mobility transistor structures grown on 4 in. Si (111) substrates. In situ measurements of wafer curvature during growth proved to be a very powerful method to analyze the buffer layer’s thickness dependent strain. The Ga/N ratio at the beginning of growth of the GaN buffer layer is the critical parameter to control the compressive strain of the entire grown structure. An engineered amount of compressive strain must be designed into the structure to perfectly compensate for the tensile strain caused by differences in the thermal expansion coefficient between the epi-layer and substrate during sample cool down from growth temperatures. A maximum film thickness of 4.2 μm was achieved without the formation of any cracks and a negligible bow of the wafers below 10 μm. Measurement of the as-grown wafers revealed depth profiles of the charge carrier concentration comparable to values achieved on SiC substrates and mobility values of the two dimensional electron gas in the range 1230 to 1350 cm2/Vs at a charge carrier concentration of 6.5–7 1012/cm2. First results on processed wafers with 2 μm thick buffer layer indicate very promising results with a resistance of the buffer, measured on 200 μm long contacts with 15 μm pitch, in the range of R > 109 Ω at 100 V and breakdown voltages up to 550 V.
Superfluid ultra-dense deuterium D(−1) on polymer surfaces: Structure and density changes at a polymer-metal boundary
Authors: Olofson Frans , Holmlid Leif
Published: June 2012

Ultra-dense deuterium D(−1) with D-D bond distance 2.3 pm is the first ultra-dense material studied. It is a superfluid quantum material and may also be superconductive. Its interaction with metal and polymer surfaces is of immediate interest. D(−1) exists on organic polymer surfaces like (poly(methyl methacrylate)) PMMA even at a distance of a few millimeter from a metal in contact with the polymer. The density of D(−1) decreases from the metal surface to the open polymer surface, and is to some extent replaced by D(1) on the polymer surface. At low surface density of D(−1), the long chain-clusters appear to lie parallel the surface, while at large densities the clusters stand vertical to the surface. Various polymers give different structures of D(−1), for example fewer non-superfluid clusters D4 are observed on fluorocarbon surfaces relative to hydrogen containing polymers. Isotope exchange reactions in four-atom clusters are probably observed between deuterium in D(−1) and protium atoms in the hydrogenated polymer surface.
Ferromagnetism of cobalt-doped anatase TiO2 studied by bulk- and surface-sensitive soft x-ray magnetic circular dichroism
Authors: Singh V. R. , Ishigami K. , Verma V. K. , Shibata G. , Yamazaki Y. , Kataoka T. , Fujimori A. , Chang F.-H. , Huang D.-J. , Lin H.-J. , Chen C. T. , Yamada Y. , Fukumura T. , Kawasaki M.
Published: June 2012

We have studied magnetism in anatase Ti1−xCoxO2−δ (x = 0.05) thin films with various electron carrier densities, by soft x-ray magnetic circular dichroism (XMCD) measurements at the Co L2,3 absorption edges. For electrically conducting samples, the magnetic moment estimated by XMCD was <0.3 μB/Co using the surface-sensitive total electron yield mode, while it was 0.3–2.4 μB/Co using the bulk-sensitive total fluorescence yield mode. The latter value is in the same range as the saturation magnetization 0.6–2.1 μB/Co deduced by SQUID measurement. The magnetization and the XMCD intensity increased with carrier density, consistent with the carrier-induced origin of the ferromagnetism.
Graphene-based photonic crystal to steer giant Faraday rotation
Authors: Da Haixia , Qiu Cheng-Wei
Published: June 2012

We present a graphene-based photonic-crystal schematic of enhancing and steering Faraday rotation angle of graphene. This concept is counter-intuitive because the giant Faraday rotation and high transmission can be simultaneously pronounced, which is distinguished from exisitng graphene structures reported before. It is found that chemical potential can be tailored to generate a controllable giant Faraday rotation via graphene with atomic thickness. By engineering the individual component thickness in the photonic crystal, the magneto-optical performance can be significantly improved. This is of fundamental importance in a wide range of magneto-optical applications, simply because the Faraday rotation makes sense only when the transmittivity is decently high.
Graphene monolayer rotation on Ni(111) facilitates bilayer graphene growth
Authors: Dahal Arjun , Addou Rafik , Sutter Peter , Batzill Matthias
Published: June 2012

Synthesis of bilayer graphene by chemical vapor deposition is of importance for graphene-based field effect devices. Here, we demonstrate that bilayer graphene preferentially grows by carbon-segregation under graphene sheets that are rotated relative to a Ni(111) substrate. Rotated graphene monolayer films can be synthesized at growth temperatures above 650 °C on a Ni(111) thin-film. The segregated second graphene layer is in registry with the Ni(111) substrate and this suppresses further C-segregation, effectively self-limiting graphene formation to two layers.
Structural and magnetic properties of thin films of BaFeO3-δ deposited by pulsed injection metal-organic chemical vapor deposition
Authors: Ribeiro B. , Borges R. P. , da Silva R. C. , Franco N. , Ferreira P. , Alves E. , Berini B. , Fouchet A. , Keller N. , Godinho M.
Published: June 2012

Thin films of BaFeO3-δ have been deposited by pulsed injection metal-organic chemical vapor deposition. The films adopt a pseudocubic structure as a result of the match with the cubic structure of the SrTiO3 substrate and the accommodation of a high density of oxygen vacancies. They display antiferromagnetic behavior at room temperature and high electrical resistance. Furthermore, we observed an ageing effect that may be recovered to some extent by annealing in oxygen atmosphere.
Superior thermal conductivity and extremely high mechanical strength in polyethylene chains from ab initio calculation
Authors: Jiang Jin-Wu , Zhao Junhua , Zhou Kun , Rabczuk Timon
Published: June 2012

The upper limit of the thermal conductivity and the mechanical strength are predicted for the polyethylene chain, by performing the ab initio calculation and applying the quantum mechanical non-equilibrium Green’s function approach. Specially, there are two main findings from our calculation: (1) the thermal conductivity can reach a high value of 310 Wm−1 K−1 in a 100 nm polyethylene chain at room temperature and the thermal conductivity increases with the length of the chain; (2) the Young’s modulus in the polyethylene chain is as high as 374.5 GPa, and the polyethylene chain can sustain 32.85%±0.05% (ultimate) strain before undergoing structural phase transition into gaseous ethylene.
Optimization of radiative recombination in terahertz quantum cascade lasers for high temperature operation
Authors: Han Y. J. , Feng W. , Cao J. C.
Published: June 2012

We investigate the temperature performance of terahertz quantum cascade lasers with different radiative recombination strength, using Monte Carlo simulation which includes electron-phonon and electron-electron scattering. The radiative and nonradiative transitions are simultaneously enhanced with the increase of optical transition matrix element. The influences on the optical mode gain are revealed by the evolution of laser levels’ lifetime, population inversion, and parasitic carrier transport paths. The calculation results indicate that the temperature performance can be further improved with an increased radiative transition matrix element around 4.0 nm. The lasing temperature above 200 K is predicted.
An interacting system of the Camassa-Holm and Degasperis-Procesi equations
Authors: Wang Mingxin , Yu Shengqi
Published: June 2012

Considered herein is the Cauchy problem of an interacting system of Camassa-Holm (C-H) and Degasperis-Procesi (D-P) equations. We first establish a precise blow-up scenario result. Then we present two blow-up results for strong solutions provided the initial data satisfy appropriate conditions.
Ultrafast photoluminescence from freestanding Si nanocrystals
Authors: Kim Sung , Shin Dong Hee , Choi Suk-Ho
Published: June 2012

SiO1.2/SiO2 multilayers were grown on n-type (100) Si wafers by ion beam sputtering and subsequently annealed at 1100 °C to form SiO2-embedded Si (S-Si) nanocrystals (NCs). The SiO2 matrix was then removed from S-Si NCs by chemical treatments to prepare freestanding Si (F-Si) NCs. The photoluminescence (PL) peak of F-Si NCs at ∼657 nm (1.89 eV) is blue-shifted with respect to that of S-Si NCs at ∼816 nm (1.52 eV). The peak shift of ∼0.37 eV is much larger than what is expected by the quantum confinement effect. The PL lifetime of F-Si NCs (∼3 ns) is much shorter than that of S-Si NCs (∼50 μs). Possible physical mechanisms are discussed to explain the origin of the fast PL band found in F-Si NCs.
Field-Based Evaluations of Horizontal Flat-Plate Fish Screens, II: Testing of a Unique Off-Stream Channel Device—the Farmers Screen
Authors: Mesa Matthew G. , Rose Brien P. , Copeland Elizabeth S.
Published: June 2012

Screens are installed at water diversion sites to reduce entrainment of fish. Recently, the Farmers Irrigation District (Oregon) developed a unique flat-plate screen (the “Farmers Screen”) that operates passively and may offer reduced installation and operating costs. To evaluate the effectiveness of this screen on fish, we conducted two separate field experiments. First, juvenile coho salmon Oncorhynchus kisutch were released over a working version of this screen under a range of inflows (0.02–0.42 m3/s) and diversion flows (0.02–0.34 m3/s) at different water depths. Mean approach velocities ranged from 0 to 5 cm/s and sweeping velocities ranged from 36 to 178 cm/s. Water depths over the screen surface ranged from 1 to 25 cm and were directly related to inflow. Passage of fish over the screen under these conditions did not severely injure them or cause delayed mortality, and no fish were observed becoming impinged on the screen surface. Second, juvenile coho salmon and steelhead O. mykiss were released at the upstream end of a 34-m flume and allowed to volitionally move downstream and pass over a 3.5-m section of the Farmers Screen to determine whether fish would refuse to pass over the screen after encountering its leading edge. For coho salmon, 75–95% of the fish passed over the screen within 5 min and 82–98% passed within 20 min, depending on hydraulic conditions. For steelhead, 47–90% of the fish passed over the screen within 5 min and 79–95% passed within 20 min. Our results indicate that when operated within its design criteria, the Farmers Screen provides safe and efficient downstream passage of juvenile salmonids under a variety of hydraulic conditions.

Received November 17, 2011; accepted March 15, 2012
Perceptions of psychotherapy trainees of psychotherapy research
Authors: Widdowson Mark
Published: June 2012

Aims: The research‐practice gap and lack of engagement with research by trainees and qualified therapists is a widely discussed issue amongst psychotherapy researchers. The present study investigates the perceptions of psychotherapy trainees of psychotherapy research and explores what would encourage them to participate in research. Method: Two focus groups of 16 trainees in total were conducted at two separate psychotherapy training institutes to explore trainees’ attitudes and perceptions. Data was analysed using Braun and Clarke's (2006) thematic analysis. Results: Three superordinate themes emerged: negative perception of research; recognition of the importance of research; and what would be needed to facilitate engagement in research. Discussion: The results suggest that interest in and willingness to participate in research exists, however it is necessary for negative perceptions about research to be addressed and for researchers to design projects which are supportive of participants.
The determinant bound for discrepancy is almost tight
Authors: Matoušek Jiří
Published: June 2012

In 1986 Lovász, Spencer, and Vesztergombi proved a lower bound for the hereditary discrepancy of a set system

F

\mathcal {F}

in terms of determinants of square submatrices of the incidence matrix of

F

\mathcal {F}

. As shown by an example of Hoffman, this bound can differ from

h
e
r
d
i
s
c

(

F

)

\mathrm {herdisc}(\mathcal {F})

by a multiplicative factor of order almost

log
⁡
n

\log n

, where

n
n

is the size of the ground set of

F

\mathcal {F}

. We prove that it never differs by more than

O
(
(
log
⁡
n

)

3

/

2

)

O((\log n)^{3/2})

, assuming

|

F

|

|\mathcal {F}|

bounded by a polynomial in 

n
n

. We also prove that if such an

F

\mathcal {F}

is the union of

t
t

systems

F

1

,
…
,

F

t

\mathcal {F}_1,\ldots ,\mathcal {F}_t

, each of hereditary discrepancy at most

D
D

, then
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal h normal e normal r normal d normal i normal s normal c left-parenthesis script upper F right-parenthesis less-than-or-equal-to upper O left-parenthesis StartRoot t EndRoot left-parenthesis log n right-parenthesis Superscript 3 slash 2 Baseline upper D right-parenthesis">

h
e
r
d
i
s
c

(

F

)
≤
O
(

t

(
log
⁡
n

)

3

/

2

D
)

\mathrm {herdisc}(\mathcal {F})\le O(\sqrt t (\log n)^{3/2}D)

. For

t
=
2

t=2

, this almost answers a question of Sós. The proof is based on a recent algorithmic result of Bansal, which computes low-discrepancy colorings using semidefinite programming.
Computability-theoretic learning complexity
Authors: Case John , Kötzing Timo
Published: June 2012

Initially discussed are some of Alan Turing's wonderfully profound and influential ideas about mind and mechanism—including regarding their connection to the main topic of the present study, which is within the field of computability-theoretic learning theory. Herein is investigated the part of this field concerned with the algorithmic, trial-and-error inference of eventually correct programs for functions from their data points. As to the main content of this study: in prior papers, beginning with the seminal work by Freivalds
et al.
in 1995, the notion of
intrinsic complexity
is used to analyse the learning complexity of
sets
of functions in a Gold-style learning setting. Herein are pointed out some weaknesses of this notion. Offered is an alternative based on
epitomizing sets
of functions—sets that are learnable under a given learning criterion, but not under other criteria that are not at least as powerful. To capture the idea of epitomizing sets, new reducibility notions are given based on
robust learning
(closure of learning under certain sets of computable operators). Various degrees of epitomizing sets are
characterized
as the sets complete with respect to corresponding reducibility notions! These characterizations also provide an easy method for showing sets to be epitomizers, and they are then employed to prove several sets to be epitomizing. Furthermore, a scheme is provided to generate easily
very strong
epitomizers for a multitude of learning criteria. These strong epitomizers are the so-called
self-learning
sets, previously applied by Case & Kötzing in 2010. These strong epitomizers can be
easily
generated and employed in a myriad of settings to witness
with certainty
the strict separation in learning power between the criteria so epitomized and other not as powerful criteria!
Less Is More? The Impact of Trauma Volume on the Positive Rate of Head Computed Tomography Scans in Head Trauma Patients
Authors: Chen Chao-Wen , Lou Yun-Ting , Chu Chi-Ming , Lin Hsing-Lin , Lee Wei-Che , Ma Ke-Zong , Cheng Yuan-Chia , Kuo Liang-Chi
Published: June 2012

Objective. Few studies have assessed the impact of trauma volume on the operational efficiency of emergency departments. Herein, we evaluate the association between trauma volume with the positive rate of head computed tomography scans in head trauma patients in a tertiary care hospital.Methods. This is a retrospective cohort review involving all head trauma patients presenting to a tertiary care hospital. Trauma census, head trauma patient volume, the number of emergent head CT scans, and the number of positive head CT scans were collected on a monthly basis. Comparison was primarily made between the trauma patient volume and the positive rate of head CT scans.Results. 25,549 trauma patients were reviewed. Of these, 5,168 (20.2%) sustained head trauma and 3,336 head CT scans were performed with mean 29.1% positive rate of substantial head injuries. The monthly data were analyzed and a statistically significant correlation between monthly trauma volume and decrease in positive rate of head CT scan was identified (Pearsonr=−0.51,P=0.02). With introducing different cut-point values of trauma volume, we identified the threshold of trauma census as approximately 4.9 and 8.8% higher than mean monthly trauma volume in discriminating significant decrease of positive rate of head CT scans.
Mixed Sequence Reader: A Program for Analyzing DNA Sequences with Heterozygous Base Calling
Authors: Chang Chun-Tien , Tsai Chi-Neu , Tang Chuan Yi , Chen Chun-Houh , Lian Jang-Hau , Hu Chi-Yu , Tsai Chia-Lung , Chao Angel , Lai Chyong-Huey , Wang Tzu-Hao , Lee Yun-Shien
Published: June 2012

The direct sequencing of PCR products generates heterozygous base-calling fluorescence chromatograms that are useful for identifying single-nucleotide polymorphisms (SNPs), insertion-deletions (indels), short tandem repeats (STRs), and paralogous genes. Indels and STRs can be easily detected using the currently available Indelligent or ShiftDetector programs, which do not search reference sequences. However, the detection of other genomic variants remains a challenge due to the lack of appropriate tools for heterozygous base-calling fluorescence chromatogram data analysis. In this study, we developed a free web-based program, Mixed Sequence Reader (MSR), which can directly analyze heterozygous base-calling fluorescence chromatogram data in .abi file format using comparisons with reference sequences. The heterozygous sequences are identified as two distinct sequences and aligned with reference sequences. Our results showed that MSR may be used to (i) physically locate indel and STR sequences and determine STR copy number by searching NCBI reference sequences; (ii) predict combinations of microsatellite patterns using the Federal Bureau of Investigation Combined DNA Index System (CODIS); (iii) determine human papilloma virus (HPV) genotypes by searching current viral databases in cases of double infections; (iv) estimate the copy number of paralogous genes, such asβ-defensin 4 (DEFB4) and its paralogHSPDP3.
Consumption of Pornographic Materials among Hong Kong Early Adolescents: A Replication
Authors: Shek Daniel T. L. , Ma Cecilia M. S.
Published: June 2012

Consumption of pornographic materials was examined in 3,638 secondary 2 students in Hong Kong. Results showed that over 80% of the respondents had never consumed pornographic materials in the past year. Internet pornography was the most common medium that adolescents used when viewing pornographic materials. Males reported a higher level of pornography consumption than did females. Participants who were born in mainland China were more likely to consume pornographic materials than their Hong Kong counterparts. Regardless of the types of pornographic materials, the levels of pornography consumption significantly increased over time. Results also showed that higher levels of positive youth development and better family functioning were concurrently related to a lower level of pornography consumption at secondary 2. The relative contribution of positive youth development and family factors to pornographic material consumption was also explored.
Subcutaneous Administration of Tramadol after Elective Surgery Is as Effective as Intravenous Administration in Relieving Acute Pain and Inflammation in Dogs
Authors: Buhari Salisu , Hashim Kalthum , Yong Meng Goh , Mustapha Noordin Mohamed , Gan Siew Hua
Published: June 2012

Subcutaneous (SC) administration of tramadol was compared with intravenous (IV) administration to evaluate analgesia following canine ovariohysterectomy (OHE). Healthy female dogs (n=12) between 1 and 3 years of age (1.95±0.65years), weighing between 10.5 and 17.1 kg (13.12±1.95 kg), were used. Pain was assessed at baseline before surgery and then hourly for 8 hr after surgery. Tramadol was administered both SC and IV at a dose of 3 mg/kg and provided significant postoperative analgesia, as indicated by analgesiometry,β-endorphin levels, and interleukin 6 (IL-6) levels. The respiratory rates and rectal temperatures remained normal and were not significantly different between or within the groups. A significant increase in heart rate was observed at 4 hr for dogs in both groups relative to the baseline, but there was no significant difference in heart rates between the groups at any time point. A significant decrease in mechanical pain threshold was observed within each group after surgery, but both groups responded similarly, suggesting that SC administration of tramadol is as effective as IV administration. Increased serum levels of both IL-6 andβ-endorphin 3 hr postoperatively further indicate that both routes of administration achieve similar pain control. Thus, the relative analgesic efficacy of SC tramadol is comparable to that of IV administration and can be used to achieve similar effects for postsurgical pain management in dogs undergoing OHE.
Associations between Pathological Gambling and Psychiatric Comorbidity among Help-Seeking Populations in Hong Kong
Authors: Shek Daniel T. L. , Chan Elda M. L. , Wong Ryan H. Y.
Published: June 2012

Problem gambling is complex and often comorbid with other mental health problems. Unfortunately, gambling studies on comorbid psychiatric disorders among Chinese communities are extremely limited. The objectives of this study were to (a) determine the prevalence of comorbid psychiatric disorders among treatment-seeking pathological gamblers; (b) compare the demographic profiles and clinical features of pathological gamblers with and without comorbid psychiatric disorders; (c) explore the associations between pathological gambling and psychiatric disorders and their temporal relationship. Participants (N=201) who sought gambling counseling were examined by making Axis-I diagnoses including mood disorders, schizophrenia spectrum disorders, substance use disorders, anxiety disorders, and adjustment disorder. Results showed that 63.7% of participants had lifetime comorbid psychiatric disorder. The most common comorbid psychiatric mental disorders were mood disorders, adjustment disorder, and substance use disorders. Pathological gamblers with psychiatric comorbidities were significantly more severe in psychopathology, psychosocial functioning impairment, and gambling problems than those without the disorders.
Critical Period of Weed Control in Aerobic Rice
Authors: Anwar M. P. , Juraimi A. S. , Samedani B. , Puteh A. , Man A.
Published: June 2012

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return.
Improved Depiction of Pterygopalatine Fossa Anatomy Using Ultrahigh-Resolution Magnetic Resonance Imaging at 7 Tesla
Authors: Oomen K. P. Q. , Pameijer F. A. , Zwanenburg J. J. M. , Hordijk G. J. , De Ru J. A. , Bleys R. L. A. W.
Published: June 2012

Purpose. To study the anatomy of the pterygopalatine fossa (PPF) using ultrahigh-resolution magnetic resonance imaging.Methods. A human cadaveric tissue block containing the pterygopalatine fossa was examined on a clinical 7-Tesla magnetic resonance imaging system. Subsequently, cryosections of the tissue block were created in a coronal plane. The cryosections were photographed and collected on adhesive tape. The on-tape sections were stained for Mallory-Cason, in order to detail the anatomic structures within the fossa. Magnetic resonance images were compared with surface photos of the tissue block and on-tape sections.Results. High-resolution magnetic resonance images demonstrated the common macroscopic structures in the PPF. Smaller structures, best viewed at the level of the operation microscope, which have previously been obscured on magnetic resonance imaging, could be depicted. Some of the orbital pterygopalatine ganglion branches and the pharyngeal nerve were clearly viewed.Conclusions. In our experience with one human cadaver specimen, magnetic resonance imaging at 7 Tesla seems effective in depicting pterygopalatine fossa anatomy and provides previously unseen details through its demonstration of the pharyngeal nerve and the orbital pterygopalatine ganglion branches. The true viability of depicting the pterygopalatine fossa with ultrahigh-resolution MR will depend on confirmation of our results in larger studies.