bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic resources of spine gourd (Momordica dioica Roxb. ex Willd.): an underexplored nutritious vegetable from tribal regions of eastern India
Authors: Bharathi L. K. , Munshi A. D. , Behera T. K. , Joseph John K. , Nath Vishal , Bisht I. S.
Published: July 2010

Spine gourd (Momordica dioica Roxb. ex Willd.) is a highly nutritious and underutilized vegetable containing high amount of protein as compared to other cucurbitaceous vegetables. Twenty-six accessions of spine gourd (M. dioica Roxb.), collected from eastern India, were evaluated to study the diversity and other genetic parameters. The estimates of genotypic coefficient of variation and phenotypic coefficient of variation for all the characters indicated that selection can be done on the basis of phenotype alone. On the basis of cluster analysis, spine gourd accessions can be categorized into three distinct groups. The accessions of spine gourd from eastern India showed an immense variation and can be used as a potential source of germplasm for crop improvement. The results presented here on nature and magnitude of genetic variability and diversity existing in this species will provide the foundation for designing an efficient spine gourd breeding programme. As spine gourd is distributed widely almost throughout India, further collections from Peninsular and Western India are suggested for maximum diversity sampling.
LOGICS AND ALGEBRAS FOR MULTIPLE PLAYERS
Authors: LOOHUIS LOES OLDE , VENEMA YDE
Published: July 2010

We study a generalization of the standard syntax and game-theoretic semantics of logic, which is based on a duality between two players, to a multiplayer setting. We define propositional and modal languages of multiplayer formulas, and provide them with a semantics involving a multiplayer game. Our focus is on the notion of equivalence between two formulas, which is defined by saying that two formulas are equivalent if under each valuation, the set of players with a winning strategy is the same in the two respective associated games. We provide a derivation system which enumerates the pairs of equivalent formulas, both in the propositional case and in the modal case. Our approach is algebraic: We introduce multiplayer algebras as the analogue of Boolean algebras, and show, as the corresponding analog to Stone’s theorem, that these abstract multiplayer algebras can be represented as concrete ones which capture the game-theoretic semantics. For the modal case we prove a similar result. We also address the computational complexity of the problem whether two given multiplayer formulas are equivalent. In the propositional case, we show that this problem is co-NP-complete, whereas in the modal case, it is PSPACE-hard.
DECIDABILITY OF INDEPENDENCE-FRIENDLY MODAL LOGIC
Authors: SEVENSTER MERLIJN
Published: July 2010

In this paper we consider an independence-friendly modal logic, IFML. It follows from results in the literature that qua expressive power, IFML is a fragment of second-order existential logic, $\Sigma _1^1$, that cannot be translated into first-order logic. It is also known that IFML lacks the tree structure property. We show that IFML has the ‘truncated structure property’, a weaker version of the tree structure property, and that its satisfiability problem is solvable in 2NEXP. This implies that this paper reveals a new decidable fragment of $\Sigma _1^1$. We also show that IFML becomes undecidable if we add the identity symbol to its vocabulary by means of a reduction from the tiling problem.
Spherical cap harmonic analysis of Super Dual Auroral Radar Network (SuperDARN) observations for generating maps of ionospheric convection
Authors: Fiori R. A. D. , Boteler D. H. , Koustov A. V. , Haines G. V. , Ruohoniemi J. M.
Published: July 2010

A spherical cap harmonic analysis (SCHA) technique is introduced for mapping the 2‐D high‐latitude ionospheric convection pattern based on Super Dual Auroral Radar Network (SuperDARN) velocity measurements. The current method for generating such maps is the FIT technique which generates global‐scale maps over the entire convection region. This is accomplished by combining observations with a statistical model to prevent unphysical solutions in areas away from the observation points and by forcing the plasma flow to zero at the low‐latitude boundary of the convection zone. Both constraints distort the mapped convection and require a preconception of where the plasma flow lines should close. By focusing on mapping the convection over a region well covered by velocity observations, the SCHA technique is freed of these constraints and more accurately reproduces local convection. We generate large‐scale convection maps from SuperDARN data for various interplanetary magnetic field (IMF) conditions during periods of widespread radar coverage to show the patterns are consistent with expectations for various IMF configurations. We validate the SCHA maps by comparing them with the 2‐D ion drifts measured by the DMSP satellites and with the 2‐D convection vectors obtained by merging SuperDARN measurements at beam crossings. The SCHA technique is shown to perform comparably to the FIT technique over regions of good data coverage. For limited data coverage and over regions of highly variable flow, particularly near the equatorward edge of the mapping region, the SCHA technique provides a better solution for mapping ionospheric convection based on SuperDARN radar observations.
Multiple scattering and mode conversion revealed by an active seismic experiment at Asama volcano, Japan
Authors: Yamamoto Mare , Sato Haruo
Published: July 2010

Volcanoes are one of the most heterogeneous fields in the Earth's crust, and the understanding of such inhomogeneities may provide us important information on various volcanic processes. In the previous studies on the seismic wave propagation at active volcanoes, the diffusion model has been widely used to model the energy transportation and the contribution of P and S waves and their mode conversion have not been well recognized partly due to lack of dense observations capturing spatiotemporal pattern of energy propagation. In this study, we present observational evidence of mode conversions and multiple scattering at Asama volcano, Japan, revealed by an active seismic experiment with a dense seismic network. The observed spatial distribution of propagating energy emitted from the explosive P source shows a wavefront of direct P wave and a pattern exhibiting two slopes which is indicative of multiple scattering and conversion scattering of two modes having different scattering coefficients. These facts suggest that the radiative transfer theory is more preferable than the diffusion theory to explain the observed characteristics. We thus modeled the energy propagation using the radiative transfer theory assuming multiple isotropic scattering including conversion scatterings and quantitatively estimated scattering parameters. Estimated total scattering coefficients for P‐to‐S and S‐to‐S scattering are about three times larger than that of P‐to‐P scattering, and the mean free path of S wave is about 1 km for an 8–16 Hz band. These results suggest that the mode conversion and multiple scattering have an indispensable effect on the seismic energy propagation in heterogeneous volcanic environments.
Wyrtki Jet dynamics: Seasonal variability
Authors: Nagura Motoki , McPhaden Michael J.
Published: July 2010

This study examines the dynamics of the Wyrtki jets, which are strong equatorial zonal flows that occur typically during boreal spring and fall in the Indian Ocean. Our diagnosis relies primarily on a continuously stratified linear longwave ocean model driven by QuikSCAT zonal winds. Model results, which compare well with satellite altimetry and in situ current observations, indicate that the zonal currents propagate westward along the equator at semiannual periods with an average speed of −1.5 m s−1. This propagation speed is three times faster than the propagation speed of the dominant wave mode in model zonal velocity, namely the first meridional, second baroclinic mode Rossby wave. We interpret this result in terms of a superposition of Rossby waves on a wind‐forced jet, with the jet stronger than the waves by a factor of 2. Sea surface height (SSH), on the other hand, shows propagating features that vary in both speed and direction from region to region. This contrasting behavior between SSH and zonal velocity results from differing influences of Kelvin and Rossby wave dynamics on the variability. These results are in many respects analogous to the distinction between SSH and zonal current behavior found in previous studies of the equatorial Pacific and Atlantic oceans on seasonal time scales.
Numerical simulation of a continental‐scale Saharan dust event
Authors: Shao Yaping , Fink Andreas H. , Klose Martina
Published: July 2010

Using an integrated dust‐storm modeling system, we simulate the severe Saharan dust episode between 1 and 10 March 2004. The simulations are compared with surface synoptic data and satellite images and are found to agree well with the observations. The synoptic systems that generated the dust storms and the evolution of the dust patterns are analyzed. It is revealed that a cyclogenesis over central Sahara, accompanied by an anticyclone over the Atlantic and a monsoon trough in the tropics, was responsible for the widespread continental‐scale dust storms in North Africa. Dust first appeared in west Sahara, then in east Sahara and much of the dust emitted from east Sahara was transported to the monsoon trough, resulting in high concentrations of suspended dust over the Sahel (column dust load up to 10 g m−2). The main dust source regions were (1) Mauritania, (2) Chad and Niger, and (3) Libya, Egypt, and Sudan. The region between 10°N and 17°N was one of net dust deposition. We estimate that 715.8 megatons (Mt) of dust was emitted from North Africa during the episode, 608.2 Mt of which was deposited to the continent, and the net dust emission was 107.6 Mt. Of the 107.6 Mt, with respect to the model domain, 7.3 Mt was deposited to the ocean, 79.8 Mt was transported across the domain boundaries, and 20.5 Mt was suspended in the atmosphere.
Water table dynamics and groundwater–surface water interaction during filling and draining of a large fluvial island due to dam‐induced river stage fluctuations
Authors: Francis Blair A. , Francis Luke K. , Cardenas M. Bayani
Published: July 2010

Dam‐controlled river stage fluctuations alter groundwater–surface water interaction between persistent bars and islands and the rivers bounding them by rapidly changing hydraulic gradients and expanding hyporheic zones. A 300‐m long and 80‐m wide sand‐gravel island with established vegetation located on the Colorado River (Austin, Texas, USA) is subjected to >1 m daily river stage variations due to upstream dam operations. Piezometer nests with probes monitored the evolution of the water table and groundwater flow paths through several cycles of dam‐induced stage fluctuations. Results show that hydraulic head and the water table within the island closely track the river stage associated with dam release. Water table mounds and depressions which overlap in time were mapped through the course of one storage‐release cycle over which >4,000 m3 of water moved in and out of the island. Dam operations have drastically altered groundwater–surface water connectivity between the Colorado River and the fluvial island aquifer by pumping substantial amounts of water in and out of the aquifer during dam release and storage cycles.
Dynamical connection between tropospheric blockings and stratospheric polar vortex
Authors: Castanheira J. M. , Barriopedro D.
Published: July 2010

The dynamical connection between Northern Hemisphere blocking events and the variability of the stratospheric polar vortex strength is studied. The analysis is based on the composite time evolution of the energy of baroclinic planetary waves during regional blocking occurrence. During Euro‐Atlantic blocking events, an in phase forcing of stationary zonal wavenumber 1 occurs. The enhanced wave amplitude is associated with a stratospheric polar vortex deceleration, which may result, at times, in Sudden Stratospheric Warming (SSW) events of displacement type. Pacific blocking composites reveal an in phase forcing of stationary zonal wavenumber 2. In most cases, the amplification of the wavenumber 2 does not reduce the vortex strength, being even accompanied by a mean vortex acceleration. However, if the amplification of wavenumber 2 is preceded by an amplification of wavenumber 1, the initial vortex deceleration forced by wavenumber 1 may be continued by wavenumber 2, and a SSW event of splitting type may occur.
High pressure, near‐liquidus phase equilibria of the Home Plate basalt Fastball and melting in the Martian mantle
Authors: Filiberto Justin , Dasgupta Rajdeep , Kiefer Walter S. , Treiman Allan H.
Published: July 2010

Near‐liquidus phase equilibria experiments have been conducted on a synthetic Fastball basalt composition, as analyzed at Home Plate plateau of Mars (Gusev Crater), to test if it represents a primitive mantle derived melt and place constraints on the temperature of the ancient mantle and on the lithosphere‐asthenosphere boundary of Mars. The Fastball basalt is multiply saturated with olivine and orthopyroxene at ∼1.2 GPa and 1430°C. Based on melting models, we predict that the Fastball composition could be produced by 13–23% equilibrium melting of the Martian mantle, with extraction of melt from the base of ∼105 km thick lithosphere. The multiple saturation for Fastball also constrains the potential temperature of the Martian mantle to be approximately 1480–1530°C with an initial melting pressure of 4.0–4.7 GPa. This potential temperature is much lower than that of the terrestrial mantle derived from similarly ancient magmas, i.e., komatiites.
Large-scale statistical analysis of early failures in Cu electromigration, Part I: Dominating mechanisms
Authors: Hauschildt Meike , Gall Martin , Hernandez Richard
Published: July 2010

With continuing scaling of Cu-based metallization, the electromigration (EM) failure risk has remained one of the most important reliability concerns for advanced process technologies. The main factors requiring attention are the activation energy related to the dominating diffusion mechanism, the current exponent as well as the median lifetimes and lognormal standard deviation values of experimentally acquired failure time distributions. In general, the origin and scaling behavior of these parameters are relatively well understood. However, the observation of strong bimodality for the electron up-flow direction in dual-inlaid Cu interconnects has added complexity. The failure voids can occur both within the via (“early” mode) or within the trench (“late” mode). Over the last few years, bimodality has been reported also in down-flow EM, leading to very short lifetimes due to small, slit-shaped voids under vias. These voids, requiring only a very limited amount of mass movement, are generally causing concerns with respect to long-term, reliable chip operation at elevated temperatures. For a more thorough investigation of the aforementioned early failure phenomena, specific test structures were designed based on the Wheatstone Bridge (WSB) technique. The use of these structures enabled an increase in the tested sample size past 800 000 for the 90 nm technology node, allowing a direct analysis of EM failure mechanisms at the single-digit ppm regime. Results indicate that down-flow EM can exhibit bimodality at very small percentage levels, not readily identifiable with standard testing methods. The activation energy for the down-flow early failure mechanism was determined to be 0.83±0.01 eV. Within the small error bounds of this large-scale statistical experiment, this value is deemed to be significantly lower than the usually reported activation energy of 0.90 eV for EM-induced diffusion along Cu/SiCN interfaces. Due to the advantages of the WSB technique, we were also able to expand the experimental temperature range down to 150 °C, coming quite close to typical operating conditions up to 125 °C. As a result of the lowered activation energy, we conclude that the down-flow early failure mode may control the chip lifetime at operating conditions. This publication contains the first part of our large-scale statistical analysis of early failures in Cu EM. In the second part of this study, we will discuss the EM scaling behavior across 90, 65, and 45 nm technologies. In addition, short-length effects will be evaluated using our large-scale, statistical approach. Utilizing the advantages of the WSB technique, the total sample size will be increased past 1.2 million.
Investigation of the interface between silicon nitride passivations and AlGaN/AlN/GaN heterostructures by C(V) characterization of metal-insulator-semiconductor-heterostructure capacitors
Authors: Fagerlind M. , Allerstam F. , Sveinbjörnsson E. Ö. , Rorsman N. , Kakanakova-Georgieva A. , Lundskog A. , Forsberg U. , Janzén E.
Published: July 2010

Capacitance-voltage [C(V)] measurements of metal-insulator-semiconductor-heterostructure capacitors are used to investigate the interface between silicon nitride passivation and AlGaN/AlN/GaN heterostructure material. AlGaN/AlN/GaN samples having different silicon nitride passivating layers, deposited using three different deposition techniques, are evaluated. Different interface state distributions result in large differences in the C(V) characteristics. A method to extract fixed charge as well as traps from the C(V) characteristics is presented. Rough estimates of the emission time constants of the traps can be extracted by careful analysis of the C(V) characteristics. The fixed charge is positive for all samples, with a density varying between 1.3×1012 and 7.1×1012 cm−2. For the traps, the peak density of interface states is varying between 16×1012 and 31×1012 cm−2 eV−1 for the three samples. It is concluded that, of the deposition methods investigated in this report, the low pressure chemical vapor deposited silicon nitride passivation shows the most promising results with regards to low densities of interface states.
Structural, magnetic, and transport properties of Permalloy for spintronic experiments
Authors: Nahrwold Gesche , Scholtyssek Jan M. , Motl-Ziegler Sandra , Albrecht Ole , Merkt Ulrich , Meier Guido
Published: July 2010

Permalloy (Ni80Fe20) is broadly used to prepare magnetic nanostructures for high-frequency experiments where the magnetization is either excited by electrical currents or magnetic fields. Detailed knowledge of the material properties is mandatory for thorough understanding its magnetization dynamics. In this work, thin Permalloy films are grown by dc-magnetron sputtering on heated substrates and by thermal evaporation with subsequent annealing. The specific resistance is determined by van der Pauw methods. Point-contact Andreev reflection is employed to determine the spin polarization of the films. The topography is imaged by atomic-force microscopy, and the magnetic microstructure by magnetic-force microscopy. Transmission-electron microscopy and transmission-electron diffraction are performed to determine atomic composition, crystal structure, and morphology. From ferromagnetic resonance absorption spectra the saturation magnetization, the anisotropy, and the Gilbert damping parameter are determined. Coercive fields and anisotropy are measured by magneto-optical Kerr magnetometry. The sum of the findings enables optimization of Permalloy for spintronic experiments.
Moving interface hydride formation in multilayered metal thin films
Authors: Kelly Stephen T. , Clemens B. M.
Published: July 2010

In order to improve the often slow reaction kinetics associated with many metal hydride hydrogen storage materials, we must first develop a detailed understanding of the limiting kinetic mechanisms associated with the materials in question. We used in situ x-ray diffraction to monitor hydride formation in highly controlled epitaxial magnesium thin films capped with a thin palladium layer to examine the kinetics of hydride formation. We compare the kinetic data with a transport-based hydride formation model and conclude that hydride formation in these films occurs via a growing hydride layer originating at the surface of the film. Diffusion of hydrogen through this growing hydride layer controls the growth rate for hydride layer thicknesses above ∼600 Å for the conditions examined, while reactions at an interface or diffusion through the fixed palladium layer control the growth rate for smaller hydride layer thicknesses.
The causal perturbation expansion revisited: Rescaling the interacting Dirac sea
Authors: Finster Felix , Grotz Andreas
Published: July 2010

The causal perturbation expansion defines the Dirac sea in the presence of a time-dependent external field. It yields an operator whose image generalizes the vacuum solutions of negative energy and thus gives a canonical splitting of the solution space into two subspaces. After giving a self-contained introduction to the ideas and techniques, we show that this operator is, in general, not idempotent. We modify the standard construction by a rescaling procedure giving a projector on the generalized negative-energy subspace. The resulting rescaled causal perturbation expansion uniquely defines the fermionic projector in terms of a series of distributional solutions of the Dirac equation. The technical core of the paper is to work out the combinatorics of the expansion in detail. It is also shown that the fermionic projector with interaction can be obtained from the free projector by a unitary transformation. We finally analyze the consequences of the rescaling procedure on the light-cone expansion.
Phase diagram and composition optimization for magnetic shape memory effect in Ni–Co–Mn–Sn alloys
Authors: Cong D. Y. , Roth S. , Pötschke M. , Hürrich C. , Schultz L.
Published: July 2010

The composition dependent phase transformation and magnetic properties of the Ni50−xCoxMn39Sn11 (0≤x≤10) alloys were systematically investigated. Based on the obtained results, the phase diagram of this alloy system was established. Considering the combination of large magnetization difference across phase transformation ΔM and small transformation entropy change ΔS, the optimal composition range of 5≤x≤8 for magnetic-field-induced phase transformation (MFIPT) and consequently magnetic shape memory effect was figured out. Furthermore, the decrease in martensitic transformation temperatures by magnetic fields and almost fully reversible MFIPT from martensite to austenite were confirmed in the alloys within this composition range.
Symmetry-adapted cluster and symmetry-adapted cluster-configuration interaction method in the polarizable continuum model: Theory of the solvent effect on the electronic excitation of molecules in solution
Authors: Cammi Roberto , Fukuda Ryoichi , Ehara Masahiro , Nakatsuji Hiroshi
Published: July 2010

In this paper we present the theory and implementation of the symmetry-adapted cluster (SAC) and symmetry-adapted cluster-configuration interaction (SAC-CI) method, including the solvent effect, using the polarizable continuum model (PCM). The PCM and SAC/SAC-CI were consistently combined in terms of the energy functional formalism. The excitation energies were calculated by means of the state-specific approach, the advantage of which over the linear-response approach has been shown. The single-point energy calculation and its analytical energy derivatives are presented and implemented, where the free-energy and its derivatives are evaluated because of the presence of solute-solvent interactions. We have applied this method to s-trans-acrolein and metylenecyclopropene of their electronic excitation in solution. The molecular geometries in the ground and excited states were optimized in vacuum and in solution, and both the vertical and adiabatic excitations were studied. The PCM-SAC/SAC-CI reproduced the known trend of the solvent effect on the vertical excitation energies but the shift values were underestimated. The excited state geometry in planar and nonplanar conformations was investigated. The importance of using state-specific methods was shown for the solvent effect on the optimized geometry in the excited state. The mechanism of the solvent effect is discussed in terms of the Mulliken charges and electronic dipole moment.
Electrostatic analysis of the interactions between charged particles of dielectric materials
Authors: Bichoutskaia Elena , Boatwright Adrian L. , Khachatourian Armik , Stace Anthony J.
Published: July 2010

An understanding of the electrostatic interactions that exist between charged particles of dielectric materials has applications that span much of chemistry, physics, biology, and engineering. Areas of interest include cloud formation, ink-jet printing, and the stability of emulsions. A general solution to the problem of calculating electrostatic interactions between charged dielectric particles is presented. The solution converges very rapidly for low values of the dielectric constant and is stable up to the point where particles touch. Through applications to unspecified particles with a range of size and charge ratios, the model shows that there exist distinct regions of dielectric space where particles with the same sign of charge are strongly attracted to one another.
Dynamic in situ spectroscopic ellipsometric study in inhomogeneous TiO2 thin-film growth
Authors: Horprathum M. , Chindaudom P. , Limnonthakul P. , Eiamchai P. , Nuntawong N. , Patthanasettakul V. , Pokaipisit A. , Limsuwan P.
Published: July 2010

We investigate the film-growth process of the inhomogeneous sputtered TiO2 thin films by the in situ real-time spectroscopic ellipsometer. The growth process of the film is analyzed by both the uniform and the island film growth models. Based on the analyses from the Ψ-Δ trajectories, the initial thin-film growth corresponds to the island film growth model for a single-layer film. As the film grows, the microstructural phase changes cause the transition from the single-to the double-layer physical model, because of the development of the inhomogeneity in the TiO2 thin film. The dynamic fits with the double-layer physical model and the Cody–Lorentz optical model indicate three different stages of the film growth: the nucleation stage, the coalescence stage, and the continuous-layer stage. Although our presented model works well for most of the experimental data, the determination of the refractive index at the ultrathin thickness may be problematic.
Multiple-pulse laser dynamic forming of metallic thin films for microscale three dimensional shapes
Authors: Li Ji , Cheng Gary J.
Published: July 2010

Laser dynamic forming (LDF) is a novel high energy rate microfabrication technique, which makes use of the shock pressure induced by laser to generate dynamic high strain rate three dimensional (3D) forming of thin films. In LDF process, a high shock pressure accelerates the workpiece to a high velocity and deforms it into complex 3D shapes. The forming velocity of the workpiece imparted by a single laser pulse with high energy may exceed the critical forming velocity of the material, and thus causing it to fracture. This problem is more severe when 3D structure of large aspect ratio needs to be formed. To overcome this problem, multiple-pulse LDF is investigated in this study. The total laser energy is evenly distributed in different laser pulses to keep the forming velocity below the critical forming velocity of the material. The effects of the multiple-pulse LDF on the deformation behavior of ultrathin foils are investigated. The deformation depth and thickness variation distribution of the formed 3D features are characterized to reveal these effects. In addition, the effects of vacuum conditions on multiple-pulse LDF process are carried out. It is found that the bounce off of the foil can be effectively reduced by multiple-pulse LDF and the final shape could be controlled much more accurately. By extending single pulse LDF to multiple-pulse LDF, the forming capability of LDF is further enhanced, and thus enlarges the applicable range of this technique.
Direct measurement of micromotion speed in a linear quadrupole trap
Authors: Wang B. , Zhang J. W. , Lu Z. H. , Wang L. J.
Published: July 2010

We demonstrate a simple method to directly measure the micromotion speed and amplitude of ions far away from the nodal line of the linear quadrupole trap using the cross-correlation technique. For the ions very close to the trap nodal line, the micromotion speed and amplitude of ions can also be deduced through linear fitting. This work gives us a direct picture to the ions’ micromotion modes at different displacements in the linear trap. With this work, an absolute measurement of the second-order Doppler effect in the research of atomic clocks based on large number of ions becomes possible.
Mechanism for shear banding in nanolayered composites
Authors: Mara N. A. , Bhattacharyya D. , Hirth J. P. , Dickerson P. , Misra A.
Published: July 2010

Recent studies have shown that two-phase nanocomposite materials with semicoherent interfaces exhibit enhanced strength, deformability, and radiation damage resistance. The remarkable behavior exhibited by these materials has been attributed to the atomistic structure of the bimetal interface that results in interfaces with low shear strength and hence, strong barriers for slip transmission due to dislocation core spreading along the weak interfaces. In this work, the low interfacial shear strength of Cu/Nb nanoscale multilayers dictates a new mechanism for shear banding and strain softening during micropillar compression. Our findings, supported by molecular dynamics simulations, provide insight on the design of nanocomposites with tailored interface structures and geometry to obtain a combination of high strength and deformability. High strength is derived from the ability of the interfaces to trap dislocations through relative ease of interfacial shear, while deformability can be maximized by controlling the effects of loading geometry on shear band formation.
Effects of nanofluids containing graphene/graphene-oxide nanosheets on critical heat flux
Authors: Park Sung Dae , Won Lee Seung , Kang Sarah , Bang In Cheol , Kim Ji Hyun , Shin Hyeon Suk , Lee Dong Wook , Won Lee Dong
Published: July 2010

The superb thermal conduction property of graphene establishes graphene as an excellent material for thermal management. In this paper, we selected graphene/graphene oxide nanosheets as the additives in nanofluids. The authors interestingly found that the highly enhanced critical heat flux (CHF) in the nanofluids containing graphene/graphene-oxide nanosheets (GON) cannot be explained by both the improved surface wettability and the capillarity of the nanoparticles deposition layer. Here we highlights that the GON nanofluid can be exploited to maximize the CHF the most efficiently by building up a characteristically ordered porous surface structure due to its own self-assembly characteristic resulting in a geometrically changed critical instability wavelength.
Improved electrical properties of Ge metal-oxide-semiconductor capacitors with high-k HfO2 gate dielectric by using La2O3 interlayer sputtered with/without N2 ambient
Authors: Xu H. X. , Xu J. P. , Li C. X. , Lai P. T.
Published: July 2010

The electrical properties of n-Ge metal-oxide-semiconductor (MOS) capacitors with HfO2/LaON or HfO2/La2O3 stacked gate dielectric (LaON or La2O3 as interlayer) are investigated. It is found that better electrical performances, including lower interface-state density, smaller gate leakage current, smaller capacitance equivalent thickness, larger k value, and negligible C-V frequency dispersion, can be achieved for the MOS device with LaON interlayer. The involved mechanism lies in that the LaON interlayer can effectively block the interdiffusions of Ge, O, and Hf, thus suppressing the growth of unstable GeOx interlayer and improving the dielectric/Ge interface quality.
Self focusing of field emitted electrons at an ellipsoidal tip
Authors: Kyritsakis A. , Kokkorakis G. C. , Xanthakis J. P. , Kirk T. L. , Pescia D.
Published: July 2010

In models of field emission the needle is usually terminated by a hemispherical cap. Here we choose to terminate it with a hemiellipsoidal cap and use a three-dimensional Wentzel–Kramers–Brillouin method for the computations. This has two important consequences: as the ellipsoid becomes more elongated, (a) the effective emission area is decreased and (b) the quantum mechanically computed electron paths converge toward the needle axis. Both mechanisms produce a self-focusing of the field emitted electrons.
Fast integrated optical switching by the protein bacteriorhodopsin
Authors: Fábián László , Wolff Elmar K. , Oroszi László , Ormos Pál , Dér András
Published: July 2010

State-of-the-art photonic integration technology is ready to provide the passive elements of optical integrated circuits, based either on silicon, glass or plastic materials. The bottleneck is to find the proper nonlinear optical (NLO) materials in waveguide-based integrated optical circuits for light-controlled active functions. Recently, we proposed an approach where the active role is performed by the chromoprotein bacteriorhodopsin as an NLO material, that can be combined with appropriate integrated optical devices. Here we present data supporting the possibility of switching based on a fast photoreaction of bacteriorhodopsin. The results are expected to have important implications for photonic switching technology.
Experimental study of Brillouin scattering in perfluorinated polymer optical fiber at telecommunication wavelength
Authors: Mizuno Yosuke , Nakamura Kentaro
Published: July 2010

Brillouin scattering properties in a perfluorinated graded-index polymer optical fiber (POF) with 120 μm core diameter were experimentally investigated using a laser with an operating wavelength of 1.55 μm. The Brillouin frequency shift and the Brillouin bandwidth were 2.83 GHz and 105 MHz, respectively. The calculated Brillouin gain coefficient of 3.09×10−11 m/W was comparable to that of fused silica fibers. The Brillouin threshold power of the 100 m POF was estimated to be 24 W, which we believe can be reduced by employing POFs with smaller cores.
Valence evaluation of LiMnO2 and related battery materials by x-ray absorption spectroscopy
Authors: Wadati H. , Hawthorn D. G. , Regier T. Z. , Chen G. , Hitosugi T. , Mizokawa T. , Tanaka A. , Sawatzky G. A.
Published: July 2010

We present an x-ray absorption study of the oxidation states of transition-metal-ions of LiMnO2 and its related materials, widely used as cathodes in Li-ion batteries. The comparison between the obtained spectrum and the configuration-interaction cluster-model calculations showed that the Mn3+ in LiMnO2 is a mixture of the high-spin and low-spin states. We found that Li deficiencies occur in the case of Cr substitution, whereas there are no Li deficiencies in the case of Ni substitution. We conclude that the substitution of charge-transfer-type Ni or Cu is effective for LiMnO2 battery materials.
Antiguiding factor of GaN-based laser diodes from UV to green
Authors: Scheibenzuber W. G. , Schwarz U. T. , Lermer T. , Lutgen S. , Strauss U.
Published: July 2010

We measure the antiguiding factor of (Al,In)GaN laser diodes emitting in the violet, blue and green spectral range by combining optical gain-spectroscopy with measurements of the charge-carrier induced refractive index change. A precise determination of the thermal resistance of the laser diodes allows us to keep the temperature of the active region constant during the whole measurement and thus to exclude any thermal effect on the refractive index. For laser diodes emitting in the range from 409 to 511 nm, the antiguiding factor at the laser wavelength is 4.1±0.5.
Graphene destruction by metal-carbide formation: An approach for patterning of metal-supported graphene
Authors: Lahiri Jayeeta , Batzill Matthias
Published: July 2010

With a combination of scanning tunneling microscopy, Auger electron spectroscopy and carbon monoxide titration the stability of graphene-Ni interfaces is investigated. Graphene supported on Ni(111) is stable to annealing temperature of 650 °C. However, if additional Ni is deposited on the surface it becomes unstable at already 100 °C and a surface-carbide is formed that allows the Ni deposit to penetrate the surface layer. Upon diffusion of all Ni deposits into the substrate, the graphene layer is reformed. The destruction of graphene by the formation of a carbide phase enables patterning of the graphene by controlled nickel deposition.
Gigantic transverse voltage induced via off-diagonal thermoelectric effect in CaxCoO2 thin films
Authors: Takahashi Kouhei , Kanno Tsutomu , Sakai Akihiro , Adachi Hideaki , Yamada Yuka
Published: July 2010

Gigantic transverse voltages exceeding several tens volt have been observed in CaxCoO2 thin films with tilted c-axis orientation upon illumination of nanosecond laser pulses. The voltage signals were highly anisotropic within the film surface showing close relation with the c-axis tilt direction. The magnitude and the decay time of the voltage strongly depended on the film thickness. These results confirm that the large laser-induced voltage originates from a phenomenon termed the off-diagonal thermoelectric effect, by which a film out-of-plane temperature gradient leads to generation of a film in-plane voltage.
ZnO single nanowire-based UV detectors
Authors: Das Sachindra Nath , Moon Kyeong-Ju , Kar Jyoti Prakash , Choi Ji-Hyuk , Xiong Junjie , Lee Tae Il , Myoung Jae-Min
Published: July 2010

In this report, ZnO single nanowire (NW)-based devices were fabricated on the same nanowire by e-beam lithography so that both sides had Ohmic contact and one side had Schottky contact. Information about the mechanism for low-power UV detection by these devices was unambiguously provided by I-V measurements. Adsorption and desorption of oxygen molecules at the NW surface are responsible for the UV detection by the device with Ohmic contacts on both sides. Barrier height modulations and interface states are responsible for UV detection by the device with Schottky contact on one side.
Mode-dependent dispersion in Raman line shapes: Observation and implications from ultrafast Raman loss spectroscopy
Authors: Umapathy S. , Mallick B. , Lakshmanna A.
Published: July 2010

Ultrafast Raman loss spectroscopy (URLS) enables one to obtain the vibrational structural information of molecular systems including fluorescent materials. URLS, a nonlinear process analog to stimulated Raman gain, involves a narrow bandwidth picosecond Raman pump pulse and a femtosecond broadband white light continuum. Under nonresonant condition, the Raman response appears as a negative (loss) signal, whereas, on resonance with the electronic transition the line shape changes from a negative to a positive through a dispersive form. The intensities observed and thus, the Franck–Condon activity (coordinate dependent), are sensitive to the wavelength of the white light corresponding to a particular Raman frequency with respect to the Raman pump pulse wavelength, i.e., there is a mode-dependent response in URLS.
DNA polymeraseθ up-regulation is associated with poor survival in breast cancer, perturbs DNA replication, and promotes genetic instability
Authors: Lemée Fanny , Bergoglio Valérie , Fernandez-Vidal Anne , Machado-Silva Alice , Pillaire Marie-Jeanne , Bieth Anne , Gentil Catherine , Baker Lee , Martin Anne-Laure , Leduc Claire , Lam Elena , Magdeleine Eddy , Filleron Thomas , Oumouhou Naïma , Kaina Bernd , Seki Mineaki , Grimal Fanny , Lacroix-Triki Magali , Thompson Alastair , Roché Henri , Bourdon Jean-Christophe , Wood Richard D. , Hoffmann Jean-Sébastien , Cazaux Christophe
Published: July 2010

“Replicative stress” is one of the main factors underlying neoplasia from its early stages. Genes involved in DNA synthesis may therefore represent an underexplored source of potential prognostic markers for cancer. To this aim, we generated gene expression profiles from two independent cohorts (France,n= 206; United Kingdom,n= 117) of patients with previously untreated primary breast cancers. We report here that among the 13 human nuclear DNA polymerase genes, DNA Polymerase θ (POLQ) is the only one significantly up-regulated in breast cancer compared with normal breast tissues. Importantly,POLQup-regulation significantly correlates with poor clinical outcome (4.3-fold increased risk of death in patients with highPOLQexpression), and this correlation is independent ofCyclin Eexpression or the number of positive nodes, which are currently considered as markers for poor outcome.POLQexpression provides thus an additional indicator for the survival outcome of patients with highCyclin Etumor expression or high number of positive lymph nodes. Furthermore, to decipher the molecular consequences ofPOLQup-regulation in breast cancer, we generated human MRC5-SV cell lines that stably overexpress POLQ. Strong POLQ expression was directly associated with defective DNA replication fork progression and chromosomal damage. Therefore,POLQoverexpression may be a promising genetic instability and prognostic marker for breast cancer.
Control of transpiration by radiation
Authors: Pieruschka Roland , Huber Gregor , Berry Joseph A.
Published: July 2010

The terrestrial hydrological cycle is strongly influenced by transpiration—water loss through the stomatal pores of leaves. In this report we present studies showing that the energy content of radiation absorbed by the leaf influences stomatal control of transpiration. This observation is at odds with current concepts of how stomata sense and control transpiration, and we suggest an alternative model. Specifically, we argue that the steady-state water potential of the epidermis in the intact leaf is controlled by the difference between the radiation-controlled rate of water vapor production in the leaf interior and the rate of transpiration. Any difference between these two potentially large fluxes is made up by evaporation from (or condensation on) the epidermis, causing its water potential to pivot around this balance point. Previous work established that stomata in isolated epidermal strips respond by opening with increasing (and closing with decreasing) water potential. Thus, stomatal conductance and transpiration rate should increase when there is condensation on (and decrease when there is evaporation from) the epidermis, thus tending to maintain homeostasis of epidermal water potential. We use a model to show that such a mechanism would have control properties similar to those observed with leaves. This hypothesis provides a plausible explanation for the regulation of leaf and canopy transpiration by the radiation load and provides a unique framework for studies of the regulation of stomatal conductance by CO
2
and other factors.
Tunable recognition of the steroid α-face by adjacent π-electron density
Authors: Friščić T. , Lancaster R. W. , Fábián L. , Karamertzanis P. G.
Published: July 2010

We report a previously unknown recognition motif between the α-face of the steroid hydrocarbon backbone and π-electron-rich aromatic substrates. Our study is based on a systematic and comparative analysis of the solid-state complexation of four steroids with 24 aromatic molecules. By using the solid state as a medium for complexation, we circumvent solubility and solvent competition problems that are inherent to the liquid phase. Characterization is performed using powder and single crystal X-ray diffraction, infrared solid-state spectroscopy and is complemented by a comprehensive cocrystal structure prediction methodology that surpasses earlier computational approaches in terms of realism and complexity. Our combined experimental and theoretical approach reveals that theα⋯πstacking is of electrostatic origin and is highly dependent on the steroid backbone’s unsaturated and conjugated character. We demonstrate that theα⋯πstacking interaction can drive the assembly of molecules, in particular progesterone, into solid-state complexes without the need for additional strong interactions. It results in a marked difference in the solid-state complexation propensities of different steroids with aromatic molecules, suggesting a strong dependence of the steroid-binding afﬁnity and even physicochemical properties on the steroid’s A-ring structure. Hence, the hydrocarbon part of the steroid is a potentially important variable in structure-activity relationships for establishing the binding and signaling properties of steroids, and in the manufacture of pharmaceutical cocrystals.
Similar patterns of cortical expansion during human development and evolution
Authors: Hill Jason , Inder Terrie , Neil Jeffrey , Dierker Donna , Harwell John , Van Essen David
Published: July 2010

The cerebral cortex of the human infant at term is complexly folded in a similar fashion to adult cortex but has only one third the total surface area. By comparing 12 healthy infants born at term with 12 healthy young adults, we demonstrate that postnatal cortical expansion is strikingly nonuniform: regions of lateral temporal, parietal, and frontal cortex expand nearly twice as much as other regions in the insular and medial occipital cortex. This differential postnatal expansion may reflect regional differences in the maturity of dendritic and synaptic architecture at birth and/or in the complexity of dendritic and synaptic architecture in adults. This expression may also be associated with differential sensitivity of cortical circuits to childhood experience and insults. By comparing human and macaque monkey cerebral cortex, we infer that the pattern of human evolutionary expansion is remarkably similar to the pattern of human postnatal expansion. To account for this correspondence, we hypothesize that it is beneficial for regions of recent evolutionary expansion to remain less mature at birth, perhaps to increase the influence of postnatal experience on the development of these regions or to focus prenatal resources on regions most important for early survival.
TGF-β2 alters the characteristics of the neuromuscular junction by regulating presynaptic quantal size
Authors: Fong Sitt Wai , McLennan Ian S. , McIntyre Andrew , Reid Jayne , Shennan Kathleen I. J. , Bewick Guy S.
Published: July 2010

The amount of neurotransmitter released from a presynaptic terminal is the product of the quantal content (number of vesicles) and the presynaptic quantal size (QSpre, amount of transmitter per vesicle). QSpre varies with synaptic use, but its regulation is poorly understood. The motor nerve terminals at the neuromuscular junction (NMJ) contain TGF-β receptors. We present evidence that TGF-β2 regulates QSpre at the NMJ. Application of TGF-β2 to the rat diaphragm NMJ increased the postsynaptic response to both spontaneous and evoked release of acetylcholine, whereas antibodies to TGF-β2 or its receptor had the converse effect. L-vesamicol and bafilomycin blocked the actions of TGF-β2, indicating that TGF-β2 acts by altering the extent of vesicular filling. Recordings of the postsynaptic currents from the diaphragm were consistent with TGF-β2 having this presynaptic action and a lesser postsynaptic effect on input resistance. TGF-β2 also decreased quantal content by an atropine-sensitive pathway, indicating that this change is secondary to cholinergic feedback on vesicular release. Consequently, the net actions of TGF-β2 at the NMJ were to amplify the postsynaptic effects of spontaneous transmission and to diminish the number of vesicles used per evoked stimulus, without diminishing the amount of acetylcholine released.