bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of granuloma formation and liver fibrosis in murine schistosomiasis mekongi: a morphological comparison between Schistosoma mekongi and S. japonicum infection
Authors: SHIMADA M. , KIRINOKI M. , SHIMIZU K. , KATO-HAYASHI N. , CHIGUSA Y. , KITIKOON V. , PONGSASAKULCHOTI P. , MATSUDA H.
Published: June 2010

A histopathological study was performed to clarify the characteristics of granuloma formation and liver fibrosis in Schistosoma mekongi infection in comparison with S. japonicum infection. Mice were exposed to S. mekongi (Laotian strain) and S. japonicum (Japanese strain) cercariae, and were dissected at 6, 8, 12, 16, and 20 weeks post-exposure. In the liver, granulomas in S. mekongi infection were cellular, initially organized with foam cells, and continuously appeared in the intralobular area, while granulomas in S. japonicum infection were fibrous and did not continuously appear in the intralobular area. Portal fibrosis was not seen in S. mekongi infection, but was commonly seen in S. japonicum infection in the later weeks. Granulomas in the small intestine were seen mainly in the submucosa with foam cells in S. mekongi infection and without foam cells in S. japonicum infection. The lung granulomas contained mainly histiocytes in both S. mekongi and S. japonicum infection. The absence of portal fibrosis in S. mekongi infection allows schistosome eggs to infiltrate into the intralobular area continuously, which can be what lies behind the ultrasonographic differences; the echogenic network pattern as was seen in S. japonicum infection, has not been noted in S. mekongi infection.
Post 3.9 Ma fault activity within the West Antarctic rift system: onshore evidence from Gandalf Ridge, Mount Morning eruptive centre, southern Victoria Land, Antarctica
Authors: Martin Adam P. , Cooper Alan F.
Published: June 2010

A hawaiite dyke dated at 3.88 ± 0.05 Ma from the Mount Morning eruptive centre intrudes a diamictite deposit at Gandalf Ridge in the southern Ross Sea. The dyke has been dextrally offset up to 6 m horizontally by faults interpreted as the onshore continuation of the West Antarctic rift system (WARS) fault array. Felsic dykes emplaced during the Miocene are also present at Gandalf Ridge. The offset of the Miocene dykes is equivalent to the offset on the hawaiite dyke, suggesting that at this locality movement on faults within WARS has been restricted to a period more recent than c. 3.88 Ma. Over this period the minimum average rate of movement on these faults within WARS is 0.0015 mm yr-1.
Hierarchical cognitive and psychosocial predictors of amnestic mild cognitive impairment
Authors: HAN S. DUKE , SUZUKI HIDEO , JAK AMY J. , CHANG YU-LING , SALMON DAVID P. , BONDI MARK W.
Published: June 2010

To identify neuropsychological and psychosocial factors predictive of amnestic Mild Cognitive Impairment (aMCI) among a group of 94 nondemented older adults, we employed a novel nonlinear multivariate classification statistical method called Optimal Data Analysis (ODA) in a dataset collected annually for 3 years. Performance on measures of memory and visuomotor processing speed or symptoms of depression in year 1 predicted aMCI status by year 2. Performance on a measure of learning at year 1 predicted aMCI status at year 3. No other measures significantly predicted incidence of aMCI at years 2 and 3. Results support the utility of multiple neuropsychological and psychosocial measures in the diagnosis of aMCI, and the present model may serve as a testable hypothesis for prospective investigations of the development of aMCI. (JINS, 2010, 16, 721–729.)
Commercial Cucurbita pepo squash hybrids carrying disease resistance introgressed from Cucurbita moschata have high genetic similarity
Authors: Formisano Gelsomina , Paris Harry S. , Frusciante Luigi , Ercolano Maria R.
Published: June 2010

Production of summer squash, Cucurbita pepo, can be severely limited by viral pathogens and powdery mildew. Resistance has been introgressed from Cucurbita moschata, and resistant hybrids have been commercially deployed. Our objective was to assess genetic affinities of such hybrids with susceptible, open-pollinated cocozelle and zucchini cultivars, and two disease-resistant lines derived from six generations of backcrossing to a susceptible zucchini cultivar. Amplified fragment length polymorphism (AFLP) EcoRI/MseI primer combinations were employed and, based on the resulting polymorphic bands, genetic similarities were estimated, and an unweighted pair group method using arithmetic average (UPGMA) cluster analysis was conducted. The open-pollinated cocozelle cultivars clustered with the resistant hybrids. The hybrids had greater similarities with one another than did the open-pollinated cultivars. The zucchini cultivars and their resistant backcross lines formed their own exclusive cluster. However, the resistant backcross lines showed less than 0.80 similarity with their recurrent parent. As the chromosome number of Cucurbita is high (2n = 2x = 40) and the resistances are inherited monogenically and oligogenically, these results, after six generations of backcrossing, cannot be explained by classical genetic linkage.
Effects of lightning and sprites on the ionospheric potential, and threshold effects on sprite initiation, obtained using an analog model of the global atmospheric electric circuit
Authors: Rycroft M. J. , Odzimek A.
Published: June 2010

A quantitative model of the global atmospheric electric circuit has been constructed using the PSpice electrical engineering software package. Currents (∼1 kA) above thunderstorms and electrified rain/shower clouds raise the potential of the ionosphere (presumed to be an equipotential surface at 80 km altitude) to ∼250 kV with respect to the Earth's surface. The circuit is completed by currents flowing down through the fair‐weather atmosphere in the land/sea surface and up to the cloud systems. Using a model for the atmospheric conductivity profile, the effects of both negative and positive cloud‐to‐ground (CG) lightning discharges on the ionospheric potential have been estimated. A large positive CG discharge creates an electric field that exceeds the breakdown field from the ionosphere down to ∼74 km, thereby forming a halo, a column sprite, and some milliseconds later, from ∼67 km down to ∼55 km at ∼60 ms after the discharge, a “carrot” sprite. Estimates are made of the return stroke current and the thundercloud charge moment change of a +CG discharge required to exceed the threshold breakdown field, or the threshold field for creating and sustaining negative or positive streamers. The values for breakdown at 80 km altitude are 35 kA and 350 C.km, (Coulomb.kilometers), respectively, and those at 70 km altitude are 45 kA and 360 C.km, respectively. The different temporal and spatial developments of the mesospheric electric field distinguishing between column and carrot sprites agree with the latest deductions from recent observations. The current flowing in the highly conducting sprite reduces the ionospheric potential by ∼1 V.
Determining soil moisture and sediment availability at White Sands Dune Field, New Mexico, from apparent thermal inertia data
Authors: Scheidt Stephen , Ramsey Michael , Lancaster Nicholas
Published: June 2010

Determinations of soil moisture and sediment availability in arid regions are important indicators of local climate variability and the potential for future dust storm events. Data from the Advanced Spaceborne Thermal Emission and Reflection (ASTER) radiometer were used to derive the relationships among potential soil erosion, soil moisture, and thermal inertia (TI) at the spatial scale of aeolian landforms for the White Sands Dune Field between May 2000 and March 2008. Land surface apparent thermal inertia (ATI) data were used to derive an approximation of actual TI in order to estimate the wind threshold velocity ratio (WTR). The WTR is a ratio of the wind velocity thresholds at which soil erosion occurs for wet soil versus dry soil. The ASTER‐derived soil moisture retrievals and the changes through time at White Sands were interpreted to be driven primarily by precipitation, but the presence of a perched groundwater table may also influence certain areas. The sediment availability of dunes, active playa surfaces and the margin of the alluvial fans to the west were determined to be consistently higher than the surrounding area. The sediment availability can be primarily explained by precipitation events and the number of dry days prior to the data acquisition. Other factors such as vegetation and the amount of surface crusting may also influence soil mobility, but these were not measured in the field. This approach showed the highest modeled sediment availability values just days prior to the largest dust emission event at White Sands in decades. Such an approach could be extended to a global monitoring technique for arid land systems that are prone to dust storms and for other regional land surface studies in the Sahara.
Terrestrial and in‐stream influences on the spatial variability of nitrate in a forested headwater catchment
Authors: Scanlon Todd M. , Ingram Spencer M. , Riscassi Ami L.
Published: June 2010

A vast majority of monitoring programs designed to assess nutrient fluxes from headwater systems rely upon temporally intensive sampling at a single position within the stream network, essentially measuring the integrated response of the catchment. Missing from such an approach is spatial information related to how nutrient availability varies throughout the network, where freshwater biota live and where biogeochemical processes ultimately shape the downstream water chemistry. Here, we examine the spatial distribution of nitrate (NO3−) concentrations within the Paine Run catchment, a forested headwater catchment in Shenandoah National Park, Virginia. Nitrate concentrations throughout the stream network were measured as part of synoptic surveys conducted in 1992–1994, in the aftermath of region‐wide gypsy moth defoliation that caused dramatic increases in stream water NO3− concentrations. A follow‐up synoptic survey was conducted in 2007, when the stream water NO3− concentrations had returned to predefoliation levels. Common to each of the eight synoptic surveys were observations of multiple‐fold declines in NO3− concentration along the main stem of the stream network from the headwaters to the catchment outlet. A portion of this decline was caused by dilution, as water input by tributaries at the lower elevations of the catchment tended to have lower NO3− concentrations. A stream network model was applied to determine the relative contributions of terrestrial versus in‐stream processes to the spatial variability of the NO3− concentrations. Model results suggest that even though nitrate removal within the stream network can be substantial, terrestrial factors that determine the NO3− inputs to streams account for the vast majority of the spatial variability in stream water NO3− concentrations.
Surface and hyporheic transient storage dynamics throughout a coastal stream network
Authors: Briggs Martin A. , Gooseff Michael N. , Peterson Bruce J. , Morkeski Kate , Wollheim Wilfred M. , Hopkinson Charles S.
Published: June 2010

Transient storage of stream water and associated solutes is expected to vary along stream networks in response to related changes in stream hydraulic conditions and morphologic gradients. These spatial changes are relevant to a wide variety of processes (e.g., biogeochemical cycling), yet data regarding these dynamics are limited and almost exclusively confined to the general storage terms of transient storage models with a single‐storage zone (1‐SZ). We used a transient storage model with two‐storage zones (2‐SZ) to simulate field data from conservative solute injections conducted in a coastal stream network in Massachusetts to separately quantify surface transient storage (STS) and hyporheic transient storage (HTS). Solute tracer additions were performed at basin‐wide, low‐flow conditions, and results were compared with respect to stream size. Strong positive relationships with reach contributing area indicated that the size of the main channel and the size and residence time in surface and hyporheic storage zones all increased from small to large streams. Conversely, longitudinal dispersion and the storage zone exchange coefficients had no consistent trends downstream. The influence of storage exchange on median transport time () was consistently large for STS and negligible for HTS. When compared to 1‐SZ model estimates, we found that the general 1‐SZ model storage terms did not consistently describe either STS or HTS exchange. Overall our results indicated that many zone‐specific (STS and HTS) storage dynamics were sensitive to the combination of hydraulic and morphologic gradients along the stream network and followed positive trends with stream size.
On the non‐Gaussian nature of ionospheric vorticity
Authors: Chisham G. , Freeman M. P.
Published: June 2010

We present, for the first time, the probability density function (PDF) of ionospheric vorticity measurements made by the SuperDARN HF radars. We show that the PDF is typically heavy‐tailed and best modelled by the q‐exponential distribution across most of the ionosphere, except in the dayside region 1 current region where the Weibull distribution provides the best model. We identify these distributions as stationary solutions of a Fokker‐Planck equation whose corresponding Langevin equation can be derived from the classic baroclinic and barotropic vorticity equations, respectively.
Analysis of 3-panel and 4-panel microscale ionization sources
Authors: Natarajan Srividya , Parker Charles B. , Piascik Jeffrey R. , Gilchrist Kristin H. , Stoner Brian R. , Glass Jeffrey T.
Published: June 2010

Two designs of a microscale electron ionization (EI) source are analyzed herein: a 3-panel design and a 4-panel design. Devices were fabricated using microelectromechanical systems technology. Field emission from carbon nanotube provided the electrons for the EI source. Ion currents were measured for helium, nitrogen, and xenon at pressures ranging from 10−4 to 0.1 Torr. A comparison of the performance of both designs is presented. The 4-panel microion source showed a 10× improvement in performance compared to the 3-panel device. An analysis of the various factors affecting the performance of the microion sources is also presented. SIMION, an electron and ion optics software, was coupled with experimental measurements to analyze the ion current results. The electron current contributing to ionization and the ion collection efficiency are believed to be the primary factors responsible for the higher efficiency of the 4-panel microion source. Other improvements in device design that could lead to higher ion source efficiency in the future are also discussed. These microscale ion sources are expected to find application as stand alone ion sources as well as in miniature mass spectrometers.
A method for constructing nontraveling wave solutions for (1+1)-dimensional evolution equations
Authors: Ma Yulan , Li Bangqing
Published: June 2010

A method is proposed to construct nontraveling wave solution for (1+1)-dimensional evolution equations by extending the linear traveling wave transformation of the (G′/G)-expansion method into a nonlinear transformation. Owing to a built-in arbitrary function included in the solution, abundant solutions can be excited. Taking the Vakhnenko equation as an example, a series of nontraveling wave solutions with variable separation is obtained. Some new solutions are excited, and the known solitary wave solutions are special cases of the nontraveling wave solutions.
Metallization of the C60/Rh(100) interface revealed by valence photoelectron spectroscopy and density functional theory calculations
Authors: Wade Abdou-Ciss , Lizzit Silvano , Petaccia Luca , Goldoni Andrea , Diop Djibril , Üstünel Hande , Fabris Stefano , Baroni Stefano
Published: June 2010

The electronic structure of single and multiple layers of C60 molecules deposited on a Rh(100) surface is investigated by means of valence photoemission spectroscopy and density functional theory calculations. The binding of the fullerene monolayer to the metal surface yields the appearance of a new state in the valence band spectrum crossing the Fermi level. Insight into the metallization of the metal/fullerene interface is provided by the calculated electronic structure that allows us to correlate the measured interface state with a strong hybridization between the Rh metal states and the highest and lowest molecular orbitals. This results in a net charge transfer of ≈0.5e–0.6e from the metal to the p states of the interfacial C atoms. The charge transfer is shown to be very short range, involving only the C atoms bound to the metal. The electronic structure of the second C60 layer is already insulating and resembles the one measured for C60 multilayers supported by the same substrate or calculated for fullerenes isolated in vacuum. The discussion of the results in the context of other C60/metal systems highlights the distinctive electronic properties of the molecule/metal interface determined by the Rh support.
Hafnia: Energetics of thin films and nanoparticles
Authors: Zhou Wei , Ushakov Sergey V. , Wang Tuo , Ekerdt John G. , Demkov Alexander A. , Navrotsky Alexandra
Published: June 2010

Crystallization energetics of amorphous hafnia powders and thin films on platinum substrates was studied by differential scanning calorimetry and time-resolved high temperature x-ray diffraction. For initially amorphous 25 and 20 nm films from atomic layer deposition, crystallization enthalpy decreases from −38 to −32 kJ/mol, and crystallization temperature increases from 388 to 417 °C as thickness decreases. Enthalpy of water vapor adsorption on the surface of monoclinic hafnia was measured for both bulk powder and nanoparticles and was found to vary from −110 to −130 kJ/mol for coverage of ∼5 H2O/nm2. The enthalpies of monoclinic hafnia with various surface areas, prepared by crystallization and annealing of an amorphous hafnia precursor, were measured by high temperature oxide melt solution calorimetry. Under the previously used assumption that the interfacial enthalpy is 20% of the surface enthalpy, the surface enthalpy was calculated from experimental data as 2.8±0.1 J/m2 for the hydrated surface and 3.7±0.1 J/m2 for the anhydrous hafnia surface. These values are similar to those measured previously for monoclinic zirconia.
Pulsed ion extraction diagnostics in a quadrupole ion trap linear time-of-flight mass spectrometer
Authors: Dangi Beni B. , Sassin Nicholas A. , Ervin Kent M.
Published: June 2010

Pulsed extraction techniques are investigated for a quadrupole ion trap (QIT) interfaced to a linear time-of-flight (TOF) mass analyzer. A nonfocusing short-pulse mode of operation is developed and characterized. The short-pulse mode creates a near-monoenergetic ion packet, which is useful for reaction kinetics experiments and for making diagnostic measurements of the ion cloud size in the trap. Monopolar and bipolar pulsing modes, with the voltage pulses applied to one or both QIT endcaps to extract the ions into the TOF region, are compared. Ion TOF peak distributions are characterized experimentally and by ion trajectory simulations. Also, first-order spatial (Wiley–McLaren) focusing of ions is characterized for the conventional long-pulse extraction mode. The nonparallel fields in the QIT, which serves as the first acceleration region in the linear-TOF mass spectrometer, are shown to degrade spatial focusing and mass resolution.
Multidimensional steric effect for the XeBr∗ (B, C) formation in the oriented Xe∗(P32, MJ=2)+oriented CF3Br reaction
Authors: Ohoyama H. , Oda R. , Kasai T.
Published: June 2010

Steric effect for the XeBr∗ (B, C) formation in the oriented Xe∗(P32, MJ=2)+oriented CF3Br reaction has been observed as a function of the mutual configuration between the molecular orientation and the atomic orientation in the collision frame. Molecular steric opacity function has been determined as a function of the atomic orbital alignment (LZ′) in the collision frame. The LZ′ selectivity in the molecular steric opacity function is different between the XeBr∗ (B, C) channels: For the XeBr∗ (C) channel, the LZ′=0 alignment is favorable at the molecular axis direction and the |LZ′|=1 alignment is favorable at the sideway direction, whereas for the XeBr∗ (B) channel, the LZ′=0 alignment is favorable at the sideway direction and the |LZ′|=1 alignment is favorable at the molecular axis direction. However, the shape of the steric opacity function for the XeBr∗ (B) channel at the LZ′=0 (and |LZ′|=1) alignment is similar to that for the XeBr∗ (C) channel at the |LZ′|=1 (and LZ′=0) alignment, respectively: A large molecular orientation dependence (i.e., the largest reactivity at the Br-end with the small molecular alignment dependence) is recognized for the XeBr∗ (B) channel at the LZ′=0 alignment and for the XeBr∗ (C) channel at the |LZ′|=1 alignment, whereas a large molecular alignment dependence (i.e., the largest reactivity at the Br-end with the poor reactivity at the sideway) is recognized for the XeBr∗ (B) channel at the |LZ′|=1 alignment and for the XeBr∗ (C) channel at the LZ′=0 alignment. We propose the indirect mechanism for the dark channels (Xe+Br+CF3) via the back-electron transfer from the CF3 segment (or dissociating CF3⋯Br−) to Xe+ as the origin of the significant molecular alignment dependence in the molecular steric opacity function.
Riccati equation and the problem of decoherence
Authors: Gardas Bartłomiej
Published: June 2010

The block operator matrix theory is used to investigate the problem of a single qubit. We establish a connection between the Riccati operator equation and the possibility of obtaining an exact reduced dynamics for the qubit in question. The model of the half spin particle in the rotating magnetic field coupling with the external environment is discussed. We show that the model defined in such a way can be reduced to a time independent problem.
Electroelastic coupling between membrane surface fluctuations and membrane-embedded charges: Continuum multidielectric treatment
Authors: Miloshevsky Gennady V. , Hassanein Ahmed , Partenskii Michael B. , Jordan Peter C.
Published: June 2010

The coupling of electric fields and charges with membrane-water interfacial fluctuations affects membrane electroporation, ionic conductance, and voltage gating. A modified continuum model is introduced to study charge interaction with membrane-water interfacial fluctuations in multidielectric environments. By surrounding a point charge with a low dielectric sphere, the linear Poisson–Boltzmann equation is directly solved by calculating the reaction field potential via a method that eliminates singularity contributions. This allows treatment of charges located at dielectric boundaries. Two complementary mechanisms governing charge-fluctuation interactions are considered: (1) electroelastic deformation (EED), treating the membrane as an elastic slab (smectic bilayer model), and (2) electrohydrophobic solvation (EHS), accounting for water penetration into the membrane’s hydrophobic core. EED often leads to large membrane thickness perturbations, far larger than those consistent with elastic model descriptions [M. B. Partenskii, G. V. Miloshevsky, and P. C. Jordan, Isr. J. Chem. 47, 385 (2007)]. We argue that a switch from EED to EHS can be energetically advantageous at intermediate perturbation amplitudes. Both perturbation mechanisms are simulated by introducing adjustable shapes optimized by the kinetic Monte Carlo reaction path following approach [G. V. Miloshevsky and P. C. Jordan, J. Chem. Phys. 122, 214901 (2005)]. The resulting energy profiles agree with those of recent atomistic molecular dynamics studies on translating a charged residue across a lipid bilayer [S. Dorairaj and T. W. Allen, Proc. Natl. Acad. Sci. U.S.A. 104, 4943 (2007)].
Phaselike resonance behavior in optical transmission of sandwich coaxial square ring arrays
Authors: Wu Shan , Zhou Lin , Wang Yu-min , Huang Cheng-ping , Wang Qian-jin , Wang Guo-dong , Zhu Yong-yuan
Published: June 2010

We studied the optical transmission through sandwich coaxial square ring arrays experimentally and theoretically. The hybridized mode of the localized surface-plasmons and surface-plasmon polaritons has been observed. This hybridized mode resembles the phase resonance mode in a compound grating structure and can be named as phaselike resonance mode. For the 0-phase resonance mode, energy can tunnel through the sample due to coherent constructive interference, forming a peak in the transmission spectrum. For the π-phase resonance mode, a dip appears instead. When the incident angle is increased, the π-phase resonance mode is split into two branches, one is redshifted while the other blueshifted.
Linear study of the nonmodal growth of drift waves in dusty plasmas
Authors: Manz P. , Greiner F.
Published: June 2010

The main effect of dust on drift wave turbulence is the enhancement of the nonadiabaticity. Previous work found that nonmodal behavior is important in the nonadiabatic regime of the drift wave system. Here, the modal and nonmodal properties of the linear Hasegawa–Wakatani system of dusty plasmas are investigated. The non-normality of the linear evolution operator can lead to enhanced transient growth rates compared to the modal growth rates.
Fast computation of molecular random phase approximation correlation energies using resolution of the identity and imaginary frequency integration
Authors: Eshuis Henk , Yarkony Julian , Furche Filipp
Published: June 2010

The random phase approximation (RPA) is an increasingly popular post-Kohn–Sham correlation method, but its high computational cost has limited molecular applications to systems with few atoms. Here we present an efficient implementation of RPA correlation energies based on a combination of resolution of the identity (RI) and imaginary frequency integration techniques. We show that the RI approximation to four-index electron repulsion integrals leads to a variational upper bound to the exact RPA correlation energy if the Coulomb metric is used. Auxiliary basis sets optimized for second-order Møller–Plesset (MP2) calculations are well suitable for RPA, as is demonstrated for the HEAT [A. Tajti et al., J. Chem. Phys. 121, 11599 (2004)] and MOLEKEL [F. Weigend et al., Chem. Phys. Lett. 294, 143 (1998)] benchmark sets. Using imaginary frequency integration rather than diagonalization to compute the matrix square root necessary for RPA, evaluation of the RPA correlation energy requires O(N4 log N) operations and O(N3) storage only; the price for this dramatic improvement over existing algorithms is a numerical quadrature. We propose a numerical integration scheme that is exact in the two-orbital case and converges exponentially with the number of grid points. For most systems, 30–40 grid points yield μH accuracy in triple zeta basis sets, but much larger grids are necessary for small gap systems. The lowest-order approximation to the present method is a post-Kohn–Sham frequency-domain version of opposite-spin Laplace-transform RI-MP2 [J. Jung et al., Phys. Rev. B 70, 205107 (2004)]. Timings for polyacenes with up to 30 atoms show speed-ups of two orders of magnitude over previous implementations. The present approach makes it possible to routinely compute RPA correlation energies of systems well beyond 100 atoms, as is demonstrated for the octapeptide angiotensin II.
First results obtained from the soft x-ray pulse height analyzer on experimental advanced superconducting tokamak
Authors: Xu P. , Lin S. Y. , Hu L. Q. , Duan Y. M. , Zhang J. Z. , Chen K. Y. , Zhong G. Q.
Published: June 2010

An assembly of soft x-ray pulse height analyzer system, based on silicon drift detector (SDD), has been successfully established on the experimental advanced superconducting tokamak (EAST) to measure the spectrum of soft x-ray emission (E=1–20 keV). The system, including one 15-channel SDD linear array, is installed on EAST horizontal port C. The time-resolved radial profiles of electron temperature and Kα intensities of metallic impurities have been obtained with a spatial resolution of around 7 cm during a single discharge. It was found that the electron temperatures derived from the system are in good agreement with the values from Thomson scattering measurements. The system can also be applied to the measurement of the long pulse discharge for EAST. The diagnostic system is introduced and some typical experimental results obtained from the system are also presented.
Nanograting-based compact vacuum ultraviolet spectrometer and beam profiler for in situ characterization of high-order harmonic generation light sources
Authors: Kornilov Oleg , Wilcox Russell , Gessner Oliver
Published: June 2010

A compact, versatile device for vacuum ultraviolet (VUV) beam characterization is presented. It combines the functionalities of a VUV spectrometer and a VUV beam profiler in one unit and is entirely supported by a standard DN200 CF flange. The spectrometer employs a silicon nitride transmission nanograting in combination with a microchannel plate-based imaging detector. This enables the simultaneous recording of wavelengths ranging from 10 to 80 nm with a resolution of 0.25–0.13 nm. Spatial beam profiles with diameters up to 10 mm are imaged with 0.1 mm resolution. The setup is equipped with an in-vacuum translation stage that allows for in situ switching between the spectrometer and beam profiler modes and for moving the setup out of the beam. The simple, robust design of the device is well suited for nonintrusive routine characterization of emerging laboratory- and accelerator-based VUV light sources. Operation of the device is demonstrated by characterizing the output of a femtosecond high-order harmonic generation light source.
Topology of cyclo-octane energy landscape
Authors: Martin Shawn , Thompson Aidan , Coutsias Evangelos A. , Watson Jean-Paul
Published: June 2010

Understanding energy landscapes is a major challenge in chemistry and biology. Although a wide variety of methods have been invented and applied to this problem, very little is understood about the actual mathematical structures underlying such landscapes. Perhaps the most general assumption is the idea that energy landscapes are low-dimensional manifolds embedded in high-dimensional Euclidean space. While this is a very mild assumption, we have discovered an example of an energy landscape which is nonmanifold, demonstrating previously unknown mathematical complexity. The example occurs in the energy landscape of cyclo-octane, which was found to have the structure of a reducible algebraic variety, composed of the union of a sphere and a Klein bottle, intersecting in two rings.
In vivo imaging of cancer cells with electroporation of quantum dots and multispectral imaging
Authors: Yoo Jung Sun , Won Nayoun , Kim Hong Bae , Bang Jiwon , Kim Sungjee , Ahn Saeyoung , Soh Kwang-Sup
Published: June 2010

Our understanding of dissemination and growth of cancer cells is limited by our inability for long-term followup of this process in vivo. Fluorescence molecular imaging has the potential to track cancer cells with high contrast and sensitivity in living animals. For this purpose, intracellular delivery of near-infrared fluorescence quantum dots (QDs) by electroporation offers considerable advantages over organic fluorophores and other cell tagging methods. In this research we developed a multispectral imaging system that could eliminate two major parameters compromising in vivo fluorescence imaging performance, i.e., variations in the tissue optical properties and tissue autofluorescence. We demonstrated that electroporation of QDs and multispectral imaging allowed in vivo assessment of cancer development and progression in the xenograft mouse tumor model for more than 1 month, providing a powerful means to learn more about the biology of cancer and metastasis.
Ferromagnetic nanocrystalline Gd-doped ZnO powder synthesized by coprecipitation
Authors: Dakhel A. A. , El-Hilo M.
Published: June 2010

A mixture of bi(acetylacetonato) zinc(II)hydrate and tri(dimethylglyoximato)gadolinium(III) complexes was used to synthesize Gd-doped ZnO powder. The synthesis was a result of the complexes’ thermal codecomposition. Magnetic characterizations have shown that the sample with the atomic ratio 3.5% Gd exhibited a clear ferromagnetic behavior at room temperature (RT) and demonstrated the highest saturation magnetization at 0.05 emu/g. When all the Gd ions were considered to be ferromagnetically coupled (successful doping) the analysis of moments per Gd atom resulted in a very low value (≈0.01 μB). However, when the uncorrelated spins that are responsible for the paramagnetic component were taken into account, the analysis of moment per Gd atom gave a high value (≈9 μB). These results led us to believe that successful but not complete doping may be responsible for the observed RT magnetization in these Gd doped ZnO systems. Further analysis for the irreversible component of the sample with 3.5% Gd has shown that the activated moment, upon reversal, is large (μact=1.78×106 μB). This result hints at the existence of largely correlated regions of spins. Moreover, the obtained distribution of activation energies demonstrates that the reversal mechanism cannot be due to independent regions of correlated spins. This result explains the low values of the remanence ratio and coercivity that are usually observed in such systems.
Continuous distribution of defect states and band gap narrowing in neutron irradiated GaAs
Authors: Fleming R. M. , Lang D. V. , Seager C. H. , Bielejec E. , Patrizi G. A. , Campbell J. M.
Published: June 2010

We find that fast neutron irradiated n- and p-GaAs diodes both show a broad feature in deep level transient spectroscopy (DLTS) previously studied primarily in n-GaAs and termed the “U-band.” The high temperature edge of the broad DLTS feature cuts off at the same temperature in both n- and p-GaAs suggesting that the cut off is due to the DLTS behavior expected for a continuous density of defect states that spans midgap. The band gap implied by the DLTS midgap cut off is 1.36 eV, as compared to the bulk GaAs band gap 1.52 eV. Band gap narrowing is consistent with previous measurements of lattice expansion in neutron irradiated GaAs. This leads to a model of defect cascades that are regions of narrowed band gap with defect levels that are inhomogeneously broadened. We observe, in addition, that the damage cascades are surrounded by large Coulomb barriers that prevent the complete filling of traps in the damaged regions.
Rapid magnetic heating treatment by highly charged maghemite nanoparticles on Wistar rats exocranial glioma tumors at microliter volume
Authors: Rabias Ioannis , Tsitrouli Danai , Karakosta Eleni , Kehagias Thomas , Diamantopoulos Georgios , Fardis Michael , Stamopoulos Dimosthenis , Maris Thomas G. , Falaras Polykarpos , Zouridakis Nikolaos , Diamantis Nikolaos , Panayotou Georgios , Verganelakis Dimitrios A. , Drossopoulou Garyfalia I. , Tsilibari Effie C. , Papavassiliou Georgios
Published: June 2010

One of the most significant challenges implementing colloidal magnetic nanoparticles in medicine is the efficient heating of microliter quantities by applying a low frequency alternating magnetic field. The ultimate goal is to accomplish nonsurgically the treatment of millimeter size tumors. Here, we demonstrate the synthesis, characterization, and the in vitro as well as in vivo efficiency of a dextran coated maghemite (γ-Fe2O3) ferrofluid with an exceptional response to magnetic heating. The difference to previous synthetic attempts is the high charge of the dextran coating, which according to our study maintains the colloidal stability and good dispersion of the ferrofluid during the magnetic heating stage. Specifically, in vitro 2 μl of the ferrofluid gives an outstanding temperature rise of 33 °C within 10 min, while in vivo treatment, by infusing 150 μl of the ferrofluid in animal model (rat) glioma tumors, causes an impressive cancer tissue dissolution.
Drinfel’d superdoubles and Poisson–Lie T-plurality in low dimensions
Authors: Hlavatý Ladislav , Štěpán Vojtěch , Vysoký Jan
Published: June 2010

Defining the real Lie superalgebra as real Z2-graded vector space we classify real Manin supertriples and Drinfel’d superdoubles of superdimensions (2,2), (4,2), and (2,4). The Drinfel’d doubles of the superdimension (2,2) are then used for construction of the simplest σ-models related by Poisson–Lie T-plurality.
Molecular dynamics simulations of the internal temperature dependent diffusing and epitaxial behaviors of Pd–Ag cluster beam deposition
Authors: Chen Cha’o-Kuang , Chang Shing-Cheng , Chen Chieh-Li
Published: June 2010

The molecular dynamics simulations are applied to study the internal temperature dependence of diffusing and structural properties of Pd1−xAgx bimetallic clusters and the corresponding epitaxial behaviors of deposited nanostructure on the Pd substrate in this research. In the alloy cluster, Ag atoms are found to have higher activities than Pd atoms and play a role of improving the diffusibility of Pd atoms. The analysis of the mean spreading index indicates that the surface segregation phenomena due to the different surface energy of atoms are obvious if the internal temperature of the cluster is high enough. The radial composition distributions show that the Pd-core/Ag-shell structure of the cluster of 249 atoms is obtained when the internal temperature is above 770 K. The clusters of high internal temperature deposited on the substrate also present better epitaxy than that of low internal temperature as the mean spreading index. Because of the difference of the radius of Pd and Ag, the increase in the Ag atoms of the deposited cluster doesn’t contribute to the epitaxial growth and only enhances the mean spreading index. The evaluations of atomic epitaxfactors for the cluster-assembled film reveal that some grain boundaries of (111) planes are formed during the cluster deposition process as well as the scattered nonepitaxial atoms. These nanostructures of low epitaxy would induce internal stresses of the cluster-assembled film and hence affect the mechanical and thermal properties of the thin film.
Nanoscale domains and preferred cracking planes in Pb(Zn1/3Nb2/3)O3–(6–7)% PbTiO3 single crystals studied by piezoresponse force microscopy and fractography
Authors: Wong Meng Fei , Zeng Kaiyang
Published: June 2010

This paper presents recent studies on surface and cross-sectional domain structures of Pb(Zn1/3Nb2/3)O3–(6–7)% PbTiO3 (PZN–PT) single crystals using piezoresponse force microscopy and three-point bending technique. The surface domain structures for the rhombohedral-based single crystals in (001) orientation are found to be influenced by polishing process, whereas the surface domains on the (011)-oriented single crystals are aligned along [011¯] direction, unaffected by the polishing process. On the other hand, the domain structures on the cross-sectional fracture surface show preferential alignment which agrees reasonably with the rhombohedral dipoles on the {100} and {110} planes. The differences between the surface and cross-sectional domain structures could be attributed to stress compensation between the surface strain effect and the minimization of elastic energy. In addition, both surface and cross-sectional surface demonstrate nanoscale domains, about 100–200 nm in size. Further fractography observation suggests that the preferred cracking planes for the PZN–PT single crystals are {110} and {100} planes. The {110} planes may be the slip planes along which material pile up is observed upon indentation loading. The pile up results in tensile hoop stress, producing radial cracks along the {100} cleavage planes. To accommodate the localized stress change, new ferroelastic domains by mechanical stress are then formed without interrupting the out-of-plane piezoelectric response. Since the material pile up is thought to cause enhanced toughness along {110} planes, the PZN–PT single crystal in [011]-poled orientation exhibits more superior piezoelectric properties compared to that of the [001]-poled counterpart.
The stability of a crystal with diamond structure for patchy particles with tetrahedral symmetry
Authors: Noya Eva G. , Vega Carlos , Doye Jonathan P. K. , Louis Ard A.
Published: June 2010

The phase diagram of model anisotropic particles with four attractive patches in a tetrahedral arrangement has been computed at two different values of the range of the potential, with the aim of investigating the conditions under which a diamond crystal can be formed. We find that the diamond phase is never stable for our longer-ranged potential. At low temperatures and pressures, the fluid freezes into a body-centered-cubic solid that can be viewed as two interpenetrating diamond lattices with a weak interaction between the two sublattices. Upon compression, an orientationally ordered face-centered-cubic crystal becomes more stable than the body-centered-cubic crystal, and at higher temperatures, a plastic face-centered-cubic phase is stabilized by the increased entropy due to orientational disorder. A similar phase diagram is found for the shorter-ranged potential, but at low temperatures and pressures, we also find a region over which the diamond phase is thermodynamically favored over the body-centered-cubic phase. The higher vibrational entropy of the diamond structure with respect to the body-centered-cubic solid explains why it is stable even though the enthalpy of the latter phase is lower. Some preliminary studies on the growth of the diamond structure starting from a crystal seed were performed. Even though the diamond phase is never thermodynamically stable for the longer-ranged model, direct coexistence simulations of the interface between the fluid and the body-centered-cubic crystal and between the fluid and the diamond crystal show that at sufficiently low pressures, it is quite probable that in both cases the solid grows into a diamond crystal, albeit involving some defects. These results highlight the importance of kinetic effects in the formation of diamond crystals in systems of patchy particles.
Strain screening by mobile oxygen vacancies in SrTiO3
Authors: Kim Yongsam , Disa Ankit S. , Babakol Timur E. , Brock Joel D.
Published: June 2010

Recently, Freedman et al. [Phys. Rev. B 80, 064108 (2009)] calculated the elastic dipole tensor for several types of point defects in SrTiO3 and showed that it is nearly traceless for oxygen vacancies. Thus, mobile oxygen vacancies are predicted to screen elastic strain fields. Here, we report detailed diffuse x-ray scattering measurements of bulk SrTiO3 crystals prepared with controlled oxygen vacancy distributions. We verify the traceless nature of the elastic dipole tensor of an oxygen vacancy and demonstrate both correlations between oxygen vacancies and elastic strain screening by oxygen vacancies.
Optical characteristics of GaInP/GaP double-heterostructure core-shell nanowires embedded in polydimethylsiloxane membranes
Authors: Tatebayashi J. , Mariani G. , Lin A. , Hicks R. F. , Huffaker D. L.
Published: June 2010

The authors report on the optical properties of GaInP/GaP double-heterostructure (DH) core-shell nanowires (NWs) embedded in polydimethylsiloxane (PDMS) membranes. Self-catalyzed NW structures are grown on Si (111) substrates by initiating with the formation of Ga droplets as a catalyst which is followed by the growth of GaP core and GaInP DH shells. Optical characteristics of GaInP/GaP DH core-shell NWs transferred from Si substrates into PDMS membranes show enhanced 77 K light emission at 630 nm. The signal at 775 nm from the surface states of NWs can be mitigated by embedding the NWs in a PDMS membrane that acts as a surface state passivant.
Influence of gas inertia and edge effect on squeeze film in near field acoustic levitation
Authors: Li Jin , Cao Wenwu , Liu Pinkuan , Ding Han
Published: June 2010

Detailed analysis showed that the existing theoretical models for near field acoustic levitation are not good enough to interpret the experimental data. The best existing models can only work in a small range of the squeeze numbers even with a fitting parameter. We report here a comprehensive nonlinear model, which takes into account the nonuniform surface vibration profile, gas inertia as well as entrance pressure drop at the film edge. Our model has no empirical parameters and the predicted results agree exceptionally well with our experimental measurements over a wide range of squeeze numbers.
Contactless electroreflectance study of Fermi-level pinning at the surface of cubic GaN
Authors: Kudrawiec R. , Tschumak E. , Misiewicz J. , As D. J.
Published: June 2010

Van Hoof structures C. Van Hoof, K. Deneffe, J. De Boeck, D. J. Arent, and G. Borghs, [Appl. Phys. Lett. 54, 608 (1989)] with various thicknesses of the undoped layer, for which a homogeneous built-in electric field is expected, were grown for studies of the Fermi-level pinning at the surface of cubic GaN. The built-in electric field in the undoped GaN layer was determined from contactless electroreflectance measurements of Franz–Keldysh oscillations. A good agreement between the determined and calculated electric field has been found for the Fermi-level located ∼0.4 eV below the conduction band at the surface.
Role of mode coupling on transmission properties of subwavelength composite hole-patch structures
Authors: Wang Changlei , Gu Jianqiang , Han Jiaguang , Xing Qirong , Tian Zhen , Liu Feng , Chai Lu , Li Yanfeng , Hu Minglie , Wang Qingyue , Lu Xinchao , Zhang Weili
Published: June 2010

We report the coupling between surface plasmons and dipole-localized surface plasmons in a composite hole-patch structure at terahertz frequencies. The coupling is found to be changed by increasing the inner patch size, which causes prominent resonance frequency shift in the enhanced transmission. The experimental results show good agreement with numerical simulation. The study clarifies well the nature of coupling between surface plasmons and dipole-localized surface plasmons and is thus of help to identify the role of surface plasmons in the enhanced transmission observed in subwavelength metallic structures.
In situ observations of crystalline-to-liquid and crystalline-to-gas transitions of substrate-supported Ag nanoparticles
Authors: Chen C. L. , Lee J.-G. , Arakawa K. , Mori H.
Published: June 2010

The phase transitions of silver nanoparticles on graphite and alumina substrates have been investigated using in situ high-resolution transmission electron microscopy. It was revealed that no crystalline-to-liquid transition, only a crystalline-to-gas transition, took place in graphite-supported silver nanoparticles prior to the complete disappearance of the nanoparticles; crystalline-to-liquid transition did take place in alumina-supported silver nanoparticles. The substrate-induced difference in the phase transition behavior is discussed on the basis of a thermodynamic model.
Beyond the ABC: Climate Change Policy and Theories of Social Change
Authors: Shove Elizabeth
Published: June 2010

In this short and deliberately provocative paper I reflect on what seems to be a yawning gulf between the potential contribution of the social sciences and the typically restricted models and concepts of social change embedded in contemporary environmental policy in the UK, and in other countries too. As well as making a strong case for going beyond what I refer to as the dominant paradigm of ‘ABC’—attitude, behaviour, and choice—I discuss the attractions of this model, the blind spots it creates, and the forms of governance it sustains. This exercise provides some insight into why so much relevant social theory remains so marginalised, and helps identify opportunities for making better use of existing intellectual resources.