bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic modeling of radiation belt electrons by radial diffusion simulation for a 2 month interval following the 24 March 1991 storm injection
Authors: Chu Feifei , Hudson Mary K. , Haines Paul , Shprits Yuri
Published: March 2010

Diffusive radial transport of radiation belt electrons with variable outer boundary is computed using Brautigam and Albert (2000) diffusion coefficients parameterized by Kp, modeling power level at ULF wave frequencies in the range of MeV electron drift periods. We analyzed radial diffusion during a relatively quiet 2 month interval following the 24 March 1991, prompt injection to form a new radiation belt at L* = 2.5. The radial diffusion calculation is initialized with a computed phase space density (PSD) profile using differential flux values from the CRRES HEEF instrument, covering 0.65–7.5 MeV. The outer boundary phase space density is updated using Los Alamos National Laboratory (LANL) GEO satellite fluxes, changing the ratio of PSD relative to a quiet day by assuming the outer boundary is changing proportional to the flux at a LANL GEO satellite. The location of the plasmapause Lp* is computed using a Kp‐dependent formula separating different loss rates inside and outside the plasmapause. A series of simulations for different values of the first invariant is performed for this 2 month period. The flux is then interpolated to find electron flux at a fixed energy, 1 MeV, in order to compare with the CRRES satellite 1 MeV flux. Radial diffusion appears to be the dominant mechanism for this 2 month interval, which contains moderate storms (∣Dst∣ ≲ 100). Modulation of fluxes measured by CRRES compare well with simulations of the outer zone flux peak at L* = 3–4 for moderate high‐speed stream‐driven storms, along with persistence and slow decay of the new population of electrons injected on 24 March 1991, into L* = 2.5. The strongest storm of the 2 month interval (Dst = −105 nT) produced a flux dropout, which is not well‐captured by the model, suggesting that improvements to the Kp‐parameterized loss model are needed for larger storms.
Temporally self‐similar electron distribution functions in atmospheric breakdown: The thermal runaway regime
Authors: Colman J. J. , Roussel‐Dupré R. A. , Triplett L.
Published: March 2010

Detailed Boltzmann kinetic calculations of the electron distribution functions resulting from thermal runaway in a constant electric field are presented. Thermal runaway is considered to occur when an initially thermal electron is accelerated above the 150 eV peak in the dynamical friction force in air and becomes a runaway electron. We investigate the role of runaway breakdown in situations where thermal runaway, as well as conventional breakdown, is occurring. The electric field strengths studied span the range from the threshold for runaway breakdown in air (∼0.3 MV/m at sea level) through conventional breakdown (2.4–3.2 MV/m at sea level) and exceeding the Dreicer field (25 MV/m at sea level), above which all electrons are runaways. We initiate our simulations with a population of pseudothermal electrons or with a combination of thermal and runaway (∼1 MeV) electrons. We find that when thermal runaway occurs the self‐similar electron distribution function is identical in the presence or absence of a seed runaway population. We show that attempts to obtain the electric field from remote measurements of optical line ratios are ambiguous both in the context of the absolute field and in the underlying kinetics. By considering the runaway electrons as a separate population we conclude that the avalanche rate of low‐energy electrons is equivalent to that of runaway electrons at a reduced field of 140 Td (3.8 MV/m at standard temperature and pressure). Above that field the conventional avalanche rate will control the avalanche rate of the entire population. Below that field the runaway avalanche rate will control the avalanche rate of the entire population.
RF and X‐ray source locations during the lightning attachment process
Authors: Howard J. , Uman M. A. , Biagi C. , Hill D. , Jerauld J. , Rakov V. A. , Dwyer J. , Saleh Z. , Rassoul H.
Published: March 2010

Using an eight‐station array of electric field derivative (dE/dt) sensors and colocated NaI X‐ray detectors, we have obtained 3‐D RF source locations during the leaders and attachment processes of three first strokes initiated by stepped leaders in natural cloud‐to‐ground lightning and one stroke initiated by a dart‐stepped leader in a rocket‐and‐wire triggered flash. Stepped leader and dart‐stepped leader dE/dt pulses are tracked from a few hundred meters to a few tens of meters above ground, after which pulses of different characteristics than the step pulses are observed to occur at lower altitudes. These postleader pulses include: (1) the “leader burst,” a group of pulses in the dE/dt waveform occurring just prior to the slow front in the corresponding return‐stroke electric field waveform; (2) dE/dt pulses occurring during the slow front; and (3) the fast‐transition or dominant dE/dt pulse that is usually associated with the rapid transition to peak in the return‐stroke electric field waveform. Additionally, the timing coincidence between X rays and dE/dt pulses on colocated measurements is used to examine the X‐ray production by the postleader processes. Leader bursts (LBs) are the largest X‐ray producers of the three postleader processes and exhibit propagation speeds that exceed the preceding stepped leader speeds by more than an order of magnitude. Slow‐front (SF) and fast‐transition pulses appear to originate from similar physical processes, probably the multiple connections of upward and downward leaders. However, more X‐rays are coincident with slow‐front pulses than with fast‐transition pulses.
Identification of anthropogenic and natural dust sources using Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue level 2 data
Authors: Ginoux Paul , Garbuzov Dmitri , Hsu N. Christina
Published: March 2010

Mineral dust interacts with radiation and impacts both the regional and global climate. The relative contribution of natural and anthropogenic dust sources, however, remains largely uncertain. Although human activities disturb soils and therefore enhance wind erosion, their contribution to global dust emission has never been directly evaluated because of a lack of data. The retrieval of aerosol properties over land, including deserts, using the Moderate Resolution Imaging Spectroradiometer Deep Blue algorithm makes the first direct characterization of the origin of individual sources possible. In order to separate freshly emitted dust from other aerosol types and aged dust particles, the spectral dependence of the single scattering albedo and the Angstrom wavelength exponent are used. Four years of data from the eastern part of West Africa, which includes one of the most active natural dust sources and the highest population density on the continent, are processed. Sources are identified on the basis of the persistence of significant aerosol optical depth from freshly emitted dust, and the origin is characterized as natural or anthropogenic on the basis of a land use data set. Our results indicate that although anthropogenic dust is observed less frequently and with lower optical depth than dust from natural sources in this particular region, it occupies a large area covering most of northern Nigeria and southern Chad, around Lake Chad. In addition, smaller anthropogenic sources are found as far south as 5° of latitude north, well outside the domain of most dust source inventories.
Reconstruction of subgrid‐scale topographic variability and its effect upon the spatial structure of three‐dimensional river flow
Authors: Casas M. A. , Lane S. N. , Hardy R. J. , Benito G. , Whiting P. J.
Published: March 2010

A new approach to describing the associated topography at different scales in computational fluid dynamic applications to gravel bed rivers was developed. Surveyed topographic data were interpolated, using geostatistical methods, into different spatial discretizations, and grain‐size data were used with fractal methods to reconstruct the microtopography at scales finer than the measurement (subgrid) scale. The combination of both scales of topography was then used to construct the spatial discretization of a three‐dimensional finite volume Computational Fluid Dynamics (CFD) scheme where the topography was included using a mass flux scaling approach. The method was applied and tested on a 15 m stretch of Solfatara Creek, Wyoming, United States, using spatially distributed elevation and grain‐size data. Model runs were undertaken for each topography using a steady state solution. This paper evaluates the impact of the model spatial discretization and additional reconstructed‐variability upon the spatial structure of predicted three‐dimensional flow. The paper shows how microtopography modifies the spatial structure of predicted flow at scales finer than measurement scale in terms of variability whereas the characteristic scale of predicted flow is determined by the CFD scale. Changes in microtopography modify the predicted mean velocity value by 3.6% for a mesh resolution of 5 cm whereas a change in the computational scale modifies model results by 60%. The paper also points out how the spatial variability of predicted velocities is determined by the topographic complexity at different scales of the input topographic model.
Retracted Article: On the enzymatic activity of catalase: an iron L-edge X-ray absorption study of the active centre
Authors: Bergmann Nora , Bonhommeau Sébastien , Lange Kathrin M. , Greil Stefanie M. , Eisebitt Stefan , de Groot Frank , Chergui Majed , Aziz Emad F.
Published: March 2010

Fe L2,3-edge X-ray absorption spectra of a catalase active centre in a physiological solution reveals a partial ferryl character, which stems from the proximal tyrosine residue.
Labordiagnostik bei Entzündungen: Ein Blick hinter die Kulissen der körpereigenen Reaktionen
Authors: Müller Ulrich
Published: March 2010

Warum verändert sich die Blutsenkungsgeschwindigkeit bei einer Entzündung? Was geschieht im Körper, dass eine Linksverschiebung im Differenzialblutbild zu beobachten ist oder Akute-Phase-Proteine vermehrt gebildet werden? Dr. Ulrich Müller, Bereichsleiter Immunologische Diagnostik am Labor Dr. Bayer in Stuttgart, erläutert, welche systemischen Reaktionen bei Entzündungen im Körper ablaufen, wie sie sich auswirken und welche Parameter sich dabei im Labor erhöht bzw. vermindert zeigen.
Review of 793 Facial Fractures Treated from 2001 to 2008 in A Coruña University Hospital: Types and Etiology
Authors: Pombo Maria , Luaces-Rey Ramón , Pértega Sonia , Arenaz Jorge , Crespo Jose Luis , García-Rozado Álvaro , Patiño Beatriz , López-Cedrún Jose Luis
Published: March 2010

The purpose of this article is to analyze the incidence, demographic distribution, type, and etiology of all facial fractures treated by the Department of Oral and Maxillofacial Surgery in A Coruña University Hospital (Spain) from 2001 to 2008. A descriptive and analytic retrospective study evaluated 643 patients treated for facial fracture (excluding nasal and dento-alveolar) by the Department of Oral and Maxillofacial Surgery in A Coruña University Hospital from January 2001 to December 2008. Five parameters were studied: year of the injury, gender, age, fracture type, and etiology. Six hundred and forty-three patients with 793 fractures were included. Of these, 83.2% were males and 16.8% were females. The patients’ age ranged between 18 months and 89 years, with a mean of 37.6 and a median of 33. The major cause of injury was traffic accidents (27%), followed by assaults (20.5%), accidental traumas (20.1%), sports (11%), syncopes (7.8%), rural accidents (6.1%), industrial accidents (5.1%), and suicide attempts (0.3%). In 1.1% of the patients, it was impossible to verify the etiology. The etiology of facial fractures varies from one country to another, depending on the cultural, environmental, and socioeconomic factors. In our study, the most common cause was traffic accidents, closely followed by assaults. The number of fractures due to traffic accidents has decreased in the last 3 years. Rural accidents accounted for a significantly higher percentage of fractures than that observed in other series. The number of fractures receiving a surgical treatment from 2005 to 2008 has progressively decreased.
Global attractors and their Hausdorff dimensions for a class of Kirchhoff models
Authors: Zhijian Yang
Published: March 2010

This paper studies the existence, regularity, and Hausdorff dimensions of global attractors for a class of Kirchhoff models arising in elastoplastic flow utt−div{|∇u|m−1∇u}−Δut+Δ2u+h(ut)+g(u)=f(x). It proves that under rather mild conditions, the dynamical system associated with above-mentioned models possesses in phase space X a global attractor which has further regularity in Xσ1(↪↪X) and has finite Hausdorff dimension. For application, the fact shows that for the concerned elastoplastic flow the permanent regime (global attractor) can be observed when the excitation starts from any bounded set in phase space, and the dimension of the attractor, that is, the number of degree of freedom of the turbulent phenomenon and thus the level of complexity concerning the flow, is finite.
Endurance improvement of resistance switching behaviors in the La0.7Ca0.3MnO3 film based devices with Ag–Al alloy top electrodes
Authors: Yang R. , Li X. M. , Yu W. D. , Gao X. D. , Shang D. S. , Chen L. D.
Published: March 2010

The resistance switching characteristics of the La0.7Ca0.3MnO3-based devices with the top electrodes of Ag, Ag–Al alloys with the atomic ratios of Ag:Al=2:1 (2AgAl) and Ag:Al=1:2 (Ag2Al), and Al have been investigated. The device with 2AgAl top electrode shows excellent endurance, where more than 1000 cycles of reproducible current-voltage hysteresis with stable high and low resistance states have been observed. Based on Auger electron spectroscopy measurement and the detailed investigation of current-voltage curves of these devices, it is suggested that the oxygen affinity of the metal electrode, which is determined by the chemical component of Ag and Al, has an important influence on the interface structure and the resistance switching endurance. The present work provides a possible way for the improvement of the resistance switching endurance by modulating oxygen affinity of the electrode.
Electrode artifacts in low resistance organic spin valves
Authors: Riminucci Alberto , Prezioso Mirko , Graziosi Patrizio , Newby Carol
Published: March 2010

Artifacts can originate from the inherent shortcomings of the cross bar configuration, when the resistance of the device is small compared to that of one of the electrodes. This is particularly relevant to the field of organic spintronics, in which at least one recent work overlooked this effect. We use a simplified one-dimensional resistor model and a full three-dimensional finite element method simulation to show that an increase in the resistance of one electrode appears as a decrease of the measured resistance. We found that the model agrees qualitatively but not quantitatively with observation.
Reflectance of polytetrafluoroethylene for xenon scintillation light
Authors: Silva C. , Pinto da Cunha J. , Pereira A. , Chepel V. , Lopes M. I. , Solovov V. , Neves F.
Published: March 2010

Gaseous and liquid xenon particle detectors are being used in a number of applications including dark matter search and neutrino-less double beta decay experiments. Polytetrafluoroethylene (PTFE) is often used in these detectors both as electrical insulator and as a light reflector to improve the efficiency of detection of scintillation photons. However, xenon emits in the vacuum ultraviolet (VUV) wavelength region (λ≃175 nm) where the reflecting properties of PTFE are not sufficiently known. In this work, we report on measurements of PTFE reflectance, including its angular distribution, for the xenon scintillation light. Various samples of PTFE, manufactured by different processes (extruded, expanded, skived, and pressed) have been studied. The data were interpreted with a physical model comprising both specular and diffuse reflections. The reflectance obtained for these samples ranges from about 47% to 66% for VUV light. Other fluoropolymers, namely, ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), and perfluoro-alkoxyalkane (PFA) were also measured.
Simultaneously measured signals in scanning probe microscopy with a needle sensor: Frequency shift and tunneling current
Authors: Morawski Ireneusz , Voigtländer Bert
Published: March 2010

We present combined noncontact scanning force microscopy and tunneling current images of a platinum(111) surface obtained by means of a 1 MHz quartz needle sensor. The low-frequency circuit of the tunneling current was combined with a high-frequency signal of the quartz resonator enabling full electrical operation of the sensor. The frequency shift and the tunneling current were detected simultaneously, while the feedback control loop of the topography signal was fed using one of them. In both cases, the free signal that was not connected to the feedback loop reveals proportional-integral controller errorlike behavior, which is governed by the time derivative of the topography signal. A procedure is proposed for determining the mechanical oscillation amplitude by utilizing the tunneling current also including the average tip-sample work function.
Symmetry tuning via controlled crossed-beam energy transfer on the National Ignition Facility
Authors: Michel P. , Glenzer S. H. , Divol L. , Bradley D. K. , Callahan D. , Dixit S. , Glenn S. , Hinkel D. , Kirkwood R. K. , Kline J. L. , Kruer W. L. , Kyrala G. A. , Le Pape S. , Meezan N. B. , Town R. , Widmann K. , Williams E. A. , MacGowan B. J. , Lindl J. , Suter L. J.
Published: March 2010

The Hohlraum energetics experimental campaign started in the summer of 2009 on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)]. These experiments showed good coupling of the laser energy into the targets [N. Meezan et al., Phys. Plasmas 17, 056304 (2010)]. They have also demonstrated controlled crossed-beam energy transfer between laser beams as an efficient and robust tool to tune the implosion symmetry of ignition capsules, as predicted by earlier calculations [P. Michel et al., Phys. Rev. Lett. 102, 025004 (2009)]. A new linear model calculating crossed-beam energy transfer between cones of beams on the NIF has been developed. The model has been applied to the subscale Hohlraum targets shot during the National Ignition Campaign in 2009. A good agreement can be found between the calculations and the experiments when the impaired propagation of the laser beams due to backscatter is accounted for.
Time-resolved imaging of millimeter waves using visible continuum from the positive column of a Cs–Xe dc discharge
Authors: Gitlin M. S. , Golovanov V. V. , Spivakov A. G. , Tsvetkov A. I. , Zelenogorskiy V. V.
Published: March 2010

We present a high-sensitivity technique for time-resolved imaging of millimeter waves (MMWs) using the visible continuum (VC) from the positive column (PC) of a medium-pressure Cs–Xe dc discharge. For the MMW imaging application, a uniform plasma slab of the PC of a Cs–Xe discharge with 10×8 cm2 aperture and 2 cm in thickness was generated for 45 Torr xenon. The imaging technique is based on the fact that the intensity of the e-Xe bremsstrahlung continuum from the PC increases in the visible region when the electrons in the plasma are heated by MMWs. It is shown that in the MMW intensity range from zero to the threshold of the microwave-induced plasma breakdown, the intensity of the VC from the PC of a Cs–Xe discharge increases approximately as a second-order polynomial function of the MMW intensity. The obtained experimental data agree well with our calculations of the dependence of the VC intensity on electron temperature. The Ka-band MMW field patterns at the output of conical horn antennas and in the quasioptical beam were imaged using the discharge technique. It is shown that the technique can be used for time-resolved measurement of the profiles of watt- and subwatt-level MMWs. An energy flux sensitivity of the technique of about 10 μJ/cm2 in the Ka-band was demonstrated. The temporal resolution of the technique is about 0.8 μs. Our modeling of the transient behavior of the electron temperature in the PC shows that the time history of the electron temperature variation coincides well with the measured time history of the VC intensity variation.
Electron-nuclear interactions as probes of domain motion in proteins
Authors: Shapira Boaz , Prestegard James H.
Published: March 2010

Long range interactions between nuclear spins and paramagnetic ions can serve as a sensitive monitor of internal motion of various parts of proteins, including functional loops and separate domains. In the case of interdomain motion, the interactions between the ion and NMR-observable nuclei are modulated in direction and magnitude mainly by a combination of overall and interdomain motions. The effects on observable parameters such as paramagnetic relaxation enhancement (PRE) and pseudocontact shift (PCS) can, in principle, be used to characterize motion. These parameters are frequently used for the purpose of structural refinements. However, their use to probe actual domain motions is less common and is lacking a proper theoretical treatment from a motional perspective. In this work, a suitable spin Hamiltonian is incorporated in a two body diffusion model to produce the time correlation function for the nuclear spin–paramagnetic ion interactions. Simulated observables for nuclei in different positions with respect to the paramagnetic ion are produced. Based on these simulations, it demonstrated that both the PRE and the PCS can be very sensitive probes of domain motion. Results for different nuclei within the protein sense different aspects of the motions. Some are more sensitive to the amplitude of the internal motion, others are more sensitive to overall diffusion rates, allowing separation of these contributions. Experimentally, the interaction strength can also be tuned by substitution of different paramagnetic ions or by varying magnetic field strength (in the case of lanthanides) to allow the use of more detailed diffusion models without reducing the reliability of data fitting.
Cluster synchronization in networks of coupled nonidentical dynamical systems
Authors: Lu Wenlian , Liu Bo , Chen Tianping
Published: March 2010

In this paper, we study cluster synchronization in networks of coupled nonidentical dynamical systems. The vertices in the same cluster have the same dynamics of uncoupled node system but the uncoupled node systems in different clusters are different. We present conditions guaranteeing cluster synchronization and investigate the relation between cluster synchronization and the unweighted graph topology. We indicate that two conditions play key roles for cluster synchronization: the common intercluster coupling condition and the intracluster communication. From the latter one, we interpret the two cluster synchronization schemes by whether the edges of communication paths lie in inter- or intracluster. By this way, we classify clusters according to whether the communications between pairs of vertices in the same cluster still hold if the set of edges inter- or intracluster edges is removed. Also, we propose adaptive feedback algorithms to adapting the weights of the underlying graph, which can synchronize any bi-directed networks satisfying the conditions of common intercluster coupling and intracluster communication. We also give several numerical examples to illustrate the theoretical results.
Transport properties of single-walled carbon nanotube transistors after gamma radiation treatment
Authors: Vitusevich S. A. , Sydoruk V. A. , Petrychuk M. V. , Danilchenko B. A. , Klein N. , Offenhäusser A. , Ural A. , Bosman G.
Published: March 2010

Single-walled carbon nanotube field-effect transistors (CNT-FETs) were characterized before and after gamma radiation treatment using noise spectroscopy. The results obtained demonstrate that in long channel CNT-FETs with a length of 10 μm the contribution of contact regions can be neglected. Moreover, radiation treatment with doses of 1×106 and 2×106 rad allows a considerable decrease parallel to the nanotube parasitic conductivity and even the shift region with maximal conductivity to the voltage range of nearly zero gate voltage that improves the working point of the FETs. The Hooge parameters obtained before and after gamma radiation treatment with a dose of 1×106 rad are found to be about 5×10−3. The parameters are comparable with typical values for conventional semiconductors.
Drag reduction in Stokes flows over spheres with nanostructured superhydrophilic surfaces
Authors: Byon Chan , Nam Youngsuk , Kim Sung Jin , Ju Y. Sungtaek
Published: March 2010

Nanostructured surfaces offer opportunities to modify flow induced drag on solid objects. Measurements of the terminal velocity reveal that the drag associated with laminar Stokes flows can be reduced for spheres with nanostructured superhydrophilic as well as superhydrophobic surfaces. Numerical simulations suggest that the formation of recirculating or nearly stagnant flow zones leads to significant reduction in the friction drag. Such reduction, however, is offset by an increase in the form drag that arises from nonuniform pressure distributions. Our work motivates further studies to optimally balance the friction and form drag and control resistance to laminar flows over objects with nanostructured surfaces.
Chemical verification of variational second-order density matrix based potential energy surfaces for the N2 isoelectronic series
Authors: van Aggelen Helen , Verstichel Brecht , Bultinck Patrick , Van Neck Dimitri , Ayers Paul W. , Cooper David L.
Published: March 2010

A variational optimization of the second-order density matrix under the P-, Q-, and G-conditions was carried out for a set of diatomic 14-electron molecules, including N2, O22+, NO+, CO, and CN−. The dissociation of these molecules is studied by analyzing several chemical properties (dipole moments, population analysis, and bond indices) up to the dissociation limit (10 and 20 Å). Serious chemical flaws are observed for the heteronuclear diatomics in the dissociation limit. A careful examination of the chemical properties reveals that the origin of the dissociation problem lies in the flawed description of fractionally occupied species under the P-, Q-, and G-conditions. A novel constraint is introduced that imposes the correct dissociation and enforces size consistency. The effect of this constraint is illustrated with calculations on NO+, CO, CN−, N2, and O22+.
Cold and ultracold molecules: Spotlight on orbiting resonances
Authors: Chandler David W.
Published: March 2010

There is great interest in the production of cold molecules, at temperatures below 1 K, and ultracold molecules, at temperatures below 1 mK. Such molecules have potential applications in areas ranging from precision measurement to quantum information storage and processing, and quantum gases of ultracold polar molecules are expected to exhibit novel quantum phases. In addition, cold molecules open up a new domain for collision physics, dominated by long-range forces and scattering resonances. There have been major recent advances both in cooling molecules from room temperature and in forming molecules in ultracold atomic gases. As these techniques mature, and cold and ultracold samples are more accessible, collision studies at previously unavailable energies will be possible. This spotlight article will highlight some of the background and motivation for studying collisions at low energies and will direct readers to recent articles on the recent experimental advancements.
Detecting recursive and nonrecursive filters using chaos
Authors: Carroll T. L.
Published: March 2010

Filtering a chaotic signal through a recursive [or infinite impulse response (IIR)] filter has been shown to increase the dimension of chaos under certain conditions. Filtering with a nonrecursive [or finite impulse response (FIR)] filter should not increase dimension, but it has been shown that if the FIR filter has a long tail, measurements of actual signals may appear to show a dimension increase. I simulate IIR and FIR filters that correspond to naturally occurring resonant objects, and I show that using dimension measurements, I can distinguish the filter type. These measurements could be used to detect resonances using radar, sonar, or laser signals, or to determine if a resonance is due to an IIR or an FIR filter.
Strain evolution during the silicidation of nanometer-scale SiGe semiconductor devices studied by dark field electron holography
Authors: Cooper David , Béché Armand , Hartmann Jean-Michel , Carron Véronique , Rouvière Jean-Luc
Published: March 2010

SiGe is routinely used to induce strain in modern semiconductors in order to improve the mobility of the carriers in the channel. Due to the absence of a technique that can accurately measure the strain in these devices with nanometer-scale resolution it has been difficult to assess the effects of processing such as silicidation on the compressive strain in the conduction channel. Here we show that by using dark field electron holography, the strain evolution at various stages of the device processing can be observed, showing that the silicidation process does in fact significantly reduce the strain in the conduction channel.
Direct and indirect electron transfer at a semiconductor surface with an adsorbate: Theory and application to Ag3Si(111):H
Authors: Leathers Andrew S. , Micha David A. , Kilin Dmitri S.
Published: March 2010

We consider two pathways of electron transfer induced by a light pulse between a metal cluster and a semiconductor surface. In direct excitation the pulse excites the system directly to the final (electron transferred) state. In indirect excitation the pulse first photoexcites the system to an intermediate state, which then undergoes nonadiabatic transitions to the final state. Quantum state populations are affected by energy dissipation, which occurs on two different time scales—a fast dissipation is due to electronic energy relaxation and a slow (delayed) dissipation arises from vibrational energy relaxation. A theoretical and computational treatment of these phenomena has been done in terms of a reduced density matrix satisfying a generalized Liouville–von Neumann equation. Instantaneous dissipation is described by a Lindblad term containing electronic transition rates, while the delayed dissipation is given by a time integral with a memory supermatrix term derived from the time correlation of atomic displacements in the medium. Populations and quantum coherences during photoinduced excitations are derived from Franck–Condon overlap factors and nonadiabatic electronic couplings. Photoinduced time dependent electric dipoles and related absorption intensities are given. We also examine the viability of using a memory time in the integration of the equations of motion for the reduced density matrix, where the delayed dissipation involves a limit on the duration of the memory effects, and find that this provides significant savings of computational time. We present the results for Ag3Si(111):H photoexcited by light in the visible region using electronic parameters from ab initio density functional calculations. We find that indirect electron transfer is a lot more likely for the studied transitions of this nanostructured system, and that it leads to a longer lasting electronic charge separation.
Spectral tagging by integrated photonic crystal resonators for highly sensitive and parallel detection in biochips
Authors: Martiradonna Luigi , Pisanello Ferruccio , Stomeo Tiziana , Qualtieri Antonio , Vecchio Giuseppe , Sabella Stefania , Cingolani Roberto , De Vittorio Massimo , Pompa Pier Paolo
Published: March 2010

We propose a technological approach aimed at improving biochips performances, based on an efficient spectral modeling and enhancement of markers fluorescence through the insertion of photonic crystal nanocavities (PhC-NCs) in the readout area of biochips. This strategy univocally associates a specific emission wavelength to a specific bioprobe immobilized on a nanocavity, therefore guaranteeing parallel detection of multiple elements and faster analysis time. Moreover, PhC-NCs significantly enhance the markers fluorescence, thus improving the detection sensitivity.
Effects of annealing on the local structure of Fe and Co in CoFeB/MgO/CoFeB tunnel junctions: An extended x-ray-absorption fine structure study
Authors: Rumaiz Abdul K. , Woicik J. C. , Wang W. G. , Jordan-Sweet Jean , Jaffari G. H. , Ni C. , Xiao John Q. , Chien C. L.
Published: March 2010

Extended x-ray-absorption fine structure (EXAFS) was used to study the evolution of the local structure of Fe and Co as a function of annealing time in CoFeB/MgO/CoFeB magnetic tunnel junctions. EXAFS indicates B depletion and crystallization of the CoFeB layers within a few seconds of the post growth high temperature anneal. The decrease in first-shell Debye–Waller factor and hence the increase in structural order during annealing explains the increase in tunnel magnetoresistance observed as a result of post deposition annealing.
Efficient laser-produced plasma extreme ultraviolet sources using grooved Sn targets
Authors: Harilal S. S. , Sizyuk T. , Sizyuk V. , Hassanein A.
Published: March 2010

An efficient extreme ultraviolet (EUV) generation method has been developed with the use of a CO2 laser-produced plasma from a grooved target. A ∼5% conversion efficiency from laser to 13.5 nm photons was obtained with the use of grooves in a tin target or by repeated laser pulse shots at the same target position. Modeling studies proved that the groove target controls the hydrodynamic expansion of the plasma leading to confinement which prevents the plasma escaping from the EUV production zone.
Optically band-tunable color cone lasing emission in a dye-doped cholesteric liquid crystal with a photoisomerizable chiral dopant
Authors: Lee C.-R. , Lin S.-H. , Ku H.-S. , Liu J.-H. , Yang P.-C. , Huang C.-Y. , Yeh H.-C. , Ji T.-D.
Published: March 2010

This work demonstrates the feasibility of an optically band-tunable color cone lasing emission (CCLE) based on a dye-doped cholesteric liquid crystal with a photoisomerizable chiral dopant. Experimental results indicate that the lasing band of the formed CCLE can be tuned optically among various color regions by adjusting the UV irradiated fluence. The optical band tunability of the laser is attributed to the presence of two chiral agents with twisting powers of opposite signs in the cell and the UV-irradiation-induced decrease of the right-handed twisting power of the photoisomerizable chiral dopant via trans→cis isomerization, subsequently inducing the other chiral agent to reduce the structural pitch of the cell. Total tunable wavelength range of the laser exceeds 100 nm. Moreover, the band-tunable laser exhibits a high spectral stability under illumination of a visible light or thermal treatment.
The gain effect in a magnetic plasmon waveguide
Authors: Wang Shuming , Zhu Zhihong , Cao Jingxiao , Li Tao , Liu Hui , Zhu Shining , Zhang Xiang
Published: March 2010

Loss is a crucial problem in plasmonic integrated optical circuits and metamaterials. The Er, Yb codoped gain material is introduced into a magnetic plasmon waveguide composed of a chain of nanosandwiches in order to solve the loss problem in such subwavelength waveguide. The magnetic plasmon mode and a higher order mode are chosen as the signal and pump light to enhance the radiation and pump efficiencies. The signal light propagating in the waveguide is investigated with different Er3+ doping concentration and signal decay time. It is shown that the gain effect cannot only compensate the loss but also is able to amplify the signal, when exceeding certain threshold values of doping concentration and signal decay time.
Anisotropy of domain growth in epitaxial ferroelectric capacitors
Authors: Wu D. , Vrejoiu I. , Alexe M. , Gruverman A.
Published: March 2010

Piezoresponse force microscopy (PFM) has been applied to investigate the switching kinetics in microscale epitaxial Pb(Zr,Ti)O3 capacitors. It is shown that transition from low to high field range brings about a qualitative change in domain growth kinetics, namely, laterally isotropic growth in the high fields as opposed to highly anisotropic growth in the low fields. It is suggested that anisotropy of domain growth can be attributed to orientational variations in the activation energy due to film microstructure. Fitting the switching kinetics using the Kolmogorov–Avrami–Ishibashi model shows excellent agreement with the PFM experimental data and yields the integer values of domain dimensionality.
Refugee health: a new model for delivering primary health care
Authors: Kay Margaret , Jackson Claire , Nicholson Caroline
Published: March 2010

Providing health care to newly arrived refugees within the primary health care system has proved challenging. The primary health care sector needs enhanced capacity to provide quality health care for this population. The Primary Care Amplification Model has demonstrated its capacity to deliver effective health care to patients with chronic disease such as diabetes. This paper describes the adaption of the model to enhance the delivery of health care to the refugee community. A ‘beacon’ practice with an expanded clinical capacity to deliver health care for refugees has been established. Partnerships link this practice with existing local general practices and community services. Governance involves collaboration between clinical leadership and relevant government and non-government organisations including local refugee communities. Integration with tertiary and community health sectors is facilitated and continuing education of health care providers is an important focus. Early incorporation of research in this model ensures effective feedback to inform providers of current health needs. Although implementation is currently in its formative phase, the Primary Care Amplification Model offers a flexible, yet robust framework to facilitate the delivery of quality health care to refugee patients.
Stroke maintenance exercise group: pilot study on daily functioning in long-term stroke survivors
Authors: Patterson Sarah A. , Ross-Edwards Benjamin M. , Gill Hannah L.
Published: March 2010

Typical models of stroke rehabilitation usually direct minimal resources for ongoing maintenance beyond discharge. However, there is increasing recognition of the benefits of community-based rehabilitation to maintain physical function and health in frail and disabled clients. A stroke maintenance exercise group was established to provide long-term care for stroke survivors. A pilot study was conducted to explore its effects compared with a traditional peer support group. Self-reported questionnaires, measuring daily task participation with the Home Functioning Questionnaire and quality of life with the EQ-5D, were utilised to compare twenty-two clients in the stroke maintenance exercise group and twenty-one in the peer support group. The results indicated that both these groups showed a significant increase with daily task participation over a 3-month period. However, no improvement was evident in either group on self-rated quality of life or health status, as measured by the EQ-5D. This pilot study suggests that both stroke maintenance exercise groups and peer support groups are effective with assisting long-term stroke survivors to improve participation in everyday activities. More research is recommended to further explore the long-term needs of this clinical group.
South Australian Divisions of General Practice supporting diabetes care: insights from reporting data
Authors: Moretti Cecilia , Kalucy Elizabeth , Hordacre Ann-Louise , Howard Sara
Published: March 2010

The study used public reporting data supplied by the South Australian Divisions of General Practice to examine their role and significance in supporting diabetes care in general practice. Data sources included the Annual Survey of Divisions 2002–07, and Divisions 12-month reports against National Performance Indicators for 2006–07. Results showed that Divisions combine collaboration, practice support and GP education approaches to support optimal diabetes care within general practice. Divisions commonly described their collaborative achievements in terms of connecting general practice with other diabetes providers, services, information and resources. Practice support and educational activities, which were highly interrelated, often focussed on strengthening use of chronic disease Medical Benefit Schedule items, practice nurse roles and computer and information management systems. In this way, Divisions strengthened primary care team functioning to achieve good communication and consistent standards of care between team members. Divisions detailed a range of strategies that worked well in delivering these practice-level outcomes, with implications for wider Network learning and development. These publicly available data sources provide scope for decision makers and researchers to explore other aspects of Divisions’ roles and performance.
Evidence-informed primary health care workforce policy: are we asking the right questions?
Authors: Naccarella Lucio , Buchan Jim , Brooks Peter
Published: March 2010

Australia is facing a primary health care workforce shortage. To inform primary health care (PHC) workforce policy reforms, reflection is required on ways to strengthen the evidence base and its uptake into policy making. In 2008 the Australian Primary Health Care Research Institute funded the Australian Health Workforce Institute to host Professor James Buchan, Queen Margaret University, UK, an expert in health services policy research and health workforce planning. Professor Buchan’s visit enabled over forty Australian PHC workforce mid-career and senior researchers and policy stakeholders to be involved in roundtable policy dialogue on issues influencing PHC workforce policy making. Six key thematic questions emerged. (1) What makes PHC workforce planning different? (2) Why does the PHC workforce need to be viewed in a global context? (3) What is the capacity of PHC workforce research? (4) What policy levers exist for PHC workforce planning? (5) What principles can guide PHC workforce planning? (6) What incentives exist to optimise the use of evidence in policy making? The emerging themes need to be discussed within the context of current PHC workforce policy reforms, which are focussed on increasing workforce supply (via education/training programs), changing the skill mix and extending the roles of health workers to meet patient needs. With the Australian government seeking to reform and strengthen the PHC workforce, key questions remain about ways to strengthen the PHC workforce evidence base and its uptake into PHC workforce policy making.
Temporal dynamics of spontaneous MEG activity in brain networks
Authors: de Pasquale Francesco , Della Penna Stefania , Snyder Abraham Z. , Lewis Christopher , Mantini Dante , Marzetti Laura , Belardinelli Paolo , Ciancetta Luca , Pizzella Vittorio , Romani Gian Luca , Corbetta Maurizio
Published: March 2010

Functional MRI (fMRI) studies have shown that low-frequency (<0.1 Hz) spontaneous fluctuations of the blood oxygenation level dependent (BOLD) signal during restful wakefulness are coherent within distributed large-scale cortical and subcortical networks (resting state networks, RSNs). The neuronal mechanisms underlying RSNs remain poorly understood. Here, we describe magnetoencephalographic correspondents of two well-characterized RSNs: the dorsal attention and the default mode networks. Seed-based correlation mapping was performed using time-dependent MEG power reconstructed at each voxel within the brain. The topography of RSNs computed on the basis of extended (5 min) epochs was similar to that observed with fMRI but confined to the same hemisphere as the seed region. Analyses taking into account the nonstationarity of MEG activity showed transient formation of more complete RSNs, including nodes in the contralateral hemisphere. Spectral analysis indicated that RSNs manifest in MEG as synchronous modulation of band-limited power primarily within the theta, alpha, and beta bands—that is, in frequencies slower than those associated with the local electrophysiological correlates of event-related BOLD responses.
The pronoun of address in Piers Plowman
Authors: Stenroos Merja
Published: March 2010

This paper is a study of the singular pronoun of address in Piers Plowman. Previous studies have held that Langland’s use of second-person pronouns conformed to the Old English system where the distinction between the thou and ye type pronouns was strictly based on number. This view has accorded with the assumption that singular ye in the late fourteenth century was restricted to “courtly” genres (Burnley 2003: 29). The appearance of singular ye in the manuscripts has mainly been explained by scribal interference; at best, Samuels (1988: 214) states that authorial usage is impossible to define.
The present study is based on a detailed analysis of scribal variants in all three versions of Piers Plowman. It suggests that the use of ye comes no less naturally to Langland than to Chaucer, and that it forms an integral part of the language of Piers Plowman. The extent of scribal alteration with regard to this feature was modest, and there seems to be no reason to interpret the shared usage as anything but authorial. Finally, it is suggested that the choice between thou and ye in this period was not merely a question of authorial creativity but an obligatory choice for the speaker, with real social and pragmatic implications.
The pragmatics of grammaticalisation
Authors: Nagy C. Katalin
Published: March 2010

This paper aims to identify the role of pragmatics in grammaticalisation and to highlight the particular steps in the process of the conventionalisation of conversational implicatures on the basis of a historical pragmatic study concerning the grammaticalisation of the Catalan anar ‘to go’ + infinitive construction. It also provides some comparative considerations with similar constructions in other Romance languages. The corpus contains occurrences taken from medieval Catalan chronicles. In order to reconstruct the history of anar + infinitive, the paper also considers morphological facts and other Catalan medieval periphrases.
The paper concludes that implicatures play a double role in semantic change. On the one hand, they can become part of the semantic meaning attached to a certain construction as a new semantic component. On the other hand, they can promote the salience of a certain semantic component within the semantic structure of a lexical item.
(Inter)subjectification and Korean honorifics
Authors: Park Chongwon
Published: March 2010

The traditional diachronic treatment of the Korean honorific marker LsupL is that LsupL was originally used as a referent honorific marker from the subject’s point of view. It then underwent changes to become a speaker-addressee-oriented (S-A) marker. Diverging from this traditional approach, I claim, based on a large-scale corpus-based study, that LsupL was used as a speaker-oriented marker as early as the fifteenth century. To account for Lsup-’s function change, I posit three stages for the evolution of the modern usage of LsupL. In Stage I (fifteenth century), LsupL was used to establish an honorific relation between a speaker and a referent. In a later transition stage (Stage II, sixteenth century), LsupL began to be used with the contextual restriction that the referent be the same as the addressee. Due to its high frequency, this use of speaker-addressee honorification was coded as a new standard (Stage III). This paper shows that the pragmatic function change of the Korean honorific marker is adequately accounted for by Traugott’s (2003, 2007) (inter)subjectification theory.