bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutron diffraction as a precise and reliable method for obtaining structural properties of bulk quantities of graphene
Authors: Sofer Zdeněk , Šimek Petr , Jankovský Ondřej , Sedmidubský David , Beran Přemysl , Pumera Martin
Published: September 2014

Diffraction methods are most suitable for the evaluation of the graphene structure – the number of layers and crystallite size.
Synthesis of γ-Fe2O3/TiO2 nanocomposite and its application in removal of dyes from water samples by adsorption and degradation processes
Authors: Madrakian Tayyebeh , Afkhami Abbas , Haryani Reza , Ahmadi Mazaher
Published: September 2014

A new facile route is proposed for synthesis of γ-Fe2O3/TiO2 nanocomposite.
Reversible assembly of enantiomeric helical polymers: from fibers to gels
Authors: Leiras Seila , Freire Félix , Quiñoá Emilio , Riguera Ricardo
Published: September 2014

A novel class of stereocomplexes is described by the interaction of helically complementary poly(phenylacetylene)s (PPAs) carrying an α-methoxy-α-trifluoromethylphenylacetamide pendant group.
Rapid synthesis and electrical transition in p-type delafossite CuAlO2
Authors: Mudenda Steven , Kale Girish M. , Hara Yotamu R. S.
Published: September 2014

Single phase CuAlO2 has been synthesized within 1.5 hours. AC and DC electrical measurements revealed change in conduction mechanism at 375 °C.
Treating Myofunctional Disorders: A Multiple-Baseline Study of a New Treatment Using Electropalatography
Authors: Mantie-Kozlowski Alana , Pitt Kevin
Published: September 2014

Purpose

This study assessed the benefit of using electropalatography (EPG) in treatment aimed at habilitating individuals with nonspeech orofacial myofunctional disorders (NSOMD).

Method

The study used a multiple-baseline design across 3 female participants who were referred for an evaluation and possible treatment of their NSOMD. Treatment sessions were 30 min and provided twice weekly. Participant 1 received 8 treatments, Participant 2 received 6 treatments, and Participant 3 received 4 treatments. The patterns of sensor activation produced when participants' tongues made contact with the electropalate during saliva swallows were compared with the patterns of age-matched peers. Individualized goals were developed on the basis of these comparisons.

Results

Treatment was generally effective for the established goals. Of the 3 participants, 2 met all their goals, and the 3rd participant made gains across 1 of 2 goals. Participants continued to perform above baseline levels for most targeted goals during testing 5–8 weeks posttreatment.

Conclusion

When used in skilled treatment, EPG has potential as a means of habilitating NSOMD. It may serve as a valuable tool, providing the clinician and client with information that allows for individualized treatment planning.
Bottom‐up pruning algorithm for intra‐prediction in high‐efficiency video coding
Authors: Kang D. , Kang Y. , Lee E. , Hong Y.
Published: September 2014

Intra‐prediction in high‐efficiency video coding (HEVC), in comparison with previous video coding standards, provides higher coding efficiency, at the expense of increased computational complexity. The coding efficiency is increased, mainly due to the various transform block sizes and increased number of modes. An efficient bottom‐up pruning algorithm for mode decision is presented, to reduce the computational load of intra‐prediction. Experimental results show that the proposed algorithm achieves about 39% reduction in mode decision time in intra‐prediction, compared with the HEVC test model 11.0, with negligible coding gain degradation.
Impact of low‐frequency noise variability on statistical parameter extraction in ultra‐scaled CMOS devices
Authors: Ioannidis E.G. , Theodorou C.G. , Haendler S. , Dimitriadis C.A. , Ghibaudo G.
Published: September 2014

The impact on the extracted low‐frequency noise (LFN) parameter values due to LFN variability in CMOS devices is investigated. First, it is demonstrated that the noise level dispersion follows a log normal statistical distribution. Then, based on this feature, it is explained why the mean values from the linear data are different from the mean values (or median values) calculated from the log noise data. Finally, the consequence of this finding in terms of LFN characterisation issues and Monte Carlo LFN variability circuit simulation is discussed.
Enhanced GPS interference detection and localisation
Authors: Bours A. , Cetin E. , Dempster A.G.
Published: September 2014

Low power levels of global positioning system (GPS) signals make them susceptible to radio frequency interference (RFI) from intentional or unintentional sources. Reliance of safety critical and modern applications on GPS has made GPS critical infrastructure which must be protected. Time‐difference‐of‐arrival (TDOA) is a common approach for locating emitters. The TDOAs are estimated by correlating signals received at different sensor nodes. However, RFI detection can be hampered by the in‐band GPS signals which create undesired correlation peaks that can be mistaken for weak RFI. A sub‐space projection‐based approach for removing the GPS signals and leaving the RFI is proposed, and its performance is evaluated using signals from two synchronised Spirent GPS signal generators captured using a NordNav multi‐front‐end receiver. The results show that the proposed approach can remove the GPS signals, resulting in better RFI detection and localisation performance under various scenarios.
Power system frequency management challenges – a new approach to assessing the potential of wind capacity to aid system frequency stability
Authors: Wu Lei , Infield David
Published: September 2014

With the increasing wind penetration level in power systems, transmission system operators have become concerned about frequency stability. The inertia of a variable speed wind turbine is decoupled by power electronic converters from the power network and therefore does not intrinsically contribute to power system inertia. Moreover, as wind plant progressively displaces conventional generation and their inertia, a substantial reduction in power system inertia may occur. Variable speed wind turbines can be controlled to provide synthetic inertial response to compensate for their lack of direct contribution to power system inertia. A probabilistic approach to assessing the collective inertial contributions from wind generation across a power system is proposed and is applied to the Great Britain power system. The impact of the aggregate inertial response on arresting frequency fall is examined for the case of a sudden generation loss of 1.8 GW at the time of minimum load on both a mid‐summer and a mid‐winter day. The results show that synthetic inertial response from wind can reduce the rate of fall of frequency and the minimum system frequency (nadir) following the loss of generation event.
24‐GHz Patch antenna array on cellulose‐based materials for green wireless internet applications
Authors: Poggiani Martina , Alimenti Federico , Mezzanotte Paolo , Virili Marco , Mariotti Chiara , Orecchini Giulia , Roselli Luca
Published: September 2014

A 24‐GHz patch array antenna with integrated feeding network has been fabricated exploiting a multi‐layer cellulose‐based (i.e. paper) substrate. The adopted microstrip circuitry exploits a copper adhesive laminate that is shaped by a photo‐lithographic process and transferred to the hosting substrate using a sacrificial layer. The multi‐layer structure is obtained by stacking and gluing two layers of photo‐paper with an interposed copper ground plane. The measurements show an input reflection coefficient of about −29 dB at the centre frequency, an operating bandwidth with S11 ⩽ −20 dB of 540 MHz and a gain of 7.4 dBi. The estimated radiation efficiency is 35%. The proposed design shows the feasibility of low‐cost antenna systems for green wireless internet technology and applications up to the boundary between microwaves and millimetre‐waves.
Silver nanoparticle arrays enhanced spectral surface plasmon resonance optical sensor
Authors: Zhang Wei , Ye Weixiang , Wang Cheng , Li Wenbin , Yue Zhao , Liu Guohua
Published: September 2014

An on‐chip spectral surface plasmon resonance (SPR) optical sensor with a silver nanoparticle (Ag NP) array has been designed. Dextran (Dex)‐capped Ag NP (Dex‐Ag NP) arrays were initially self‐assembled on the gold (Au) sensing film. The large perturbations and increased penetration depth of the evanescent field, which is caused by the use of the Dex‐Ag NP array self‐assembled on the Au sensing film, can effectively enhance the SPR spectral shift response. Compared with the bare Au sensing film configuration, the Au sensing film with a Dex‐Ag NP array configuration improves sensitivity from 5492 to 6613 nm/RIU.
Blood typing chip using human whole blood sample
Authors: Chang Yaw‐Jen , Huang Ching‐Wei
Published: September 2014

Blood typing is a critical test for blood transfusion and many medical procedures. Described is a disposable microfluidic blood typing chip with a simple fabrication process. The chip allows one to use human whole blood directly so that the operation sequence of a manual polybrene technique for blood typing can be conducted automatically. In addition, the determination of the extent of red blood cell agglutination can be analysed by software. The feasibility of this chip was demonstrated by ABO blood typing tests using antibody screening cells and freshly drawn venous blood samples. From the pixel count of agglutination, the chip provided correct blood typing results. This proposed microfluidic chip has the merits of smaller consumption volumes of reagents. Moreover, the simple fabrication process of the chip results in low fabrication cost.
Two-dimensional AXUV-based radiated power density diagnostics on NSTX-U
Authors: Faust I. , Delgado-Aparicio L. , Bell R. E. , Tritz K. , Diallo A. , Gerhardt S. P. , LeBlanc B. , Kozub T. A. , Parker R. R. , Stratton B. C.
Published: September 2014

A new set of radiated-power-density diagnostics for the National Spherical Torus Experiment Upgrade (NSTX-U) tokamak have been designed to measure the two-dimensional poloidal structure of the total photon emissivity profile in order to perform power balance, impurity transport, and magnetohydrodynamic studies. Multiple AXUV-diode based pinhole cameras will be installed in the same toroidal angle at various poloidal locations. The local emissivity will be obtained from several types of tomographic reconstructions. The layout and response expected for the new radially viewing poloidal arrays will be shown for different impurity concentrations to characterize the diagnostic sensitivity. The radiated power profile inverted from the array data will also be used for estimates of power losses during transitions from various divertor configurations in NSTX-U. The effect of in-out and top/bottom asymmetries in the core radiation from high-Z impurities will be addressed.
Morphology and local organization of water-containing (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide reverse micelles dispersed in toluene
Authors: Longo Alessandro , Giannici Francesco , Portale Giuseppe , Banerjee Dipanjan , Calandra Pietro , Liveri Vincenzo Turco
Published: September 2014

The structure of (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) reverse micelles, at various water-to-surfactant molar ratio (Rw, Rw = [water]/[DMEB]) and DMEB concentrations, has been investigated by small angle X-ray scattering (SAXS) and extended X-ray absorption fine structure spectroscopy (EXAFS). SAXS data of dry reverse micelles are consistent with a model of spherical hydrophilic core surrounded by DMEB alkyl chains whose polydispersity decreases significantly with surfactant concentration. By adding water, a sphere to cylinder transition occurs leading to a one-dimensional growth of reverse micellar cores with Rw and surfactant concentration. The observed behavior was taken as an indication that water molecules are confined in the core of DMEB reverse micelles, quite uniformly distributed among them and mainly located among surfactant head groups. EXAFS data allow to focus within the hydrophilic micellar core to solve the short range local environment around the Br− counterion and to follow its changing with surfactant concentration and Rw. Analysis of Fourier transform of the EXAFS spectra indicates the existence of a local order nearby the bromide ions; pointing toward a quite structured hydrophilic core of DMEB reverse micelles. However, as a consequence of the fluid nature of reverse micelles, such local order is lower than that found in the lamellar structure of solid DMEB. Water confinement within the reverse micellar cores induces an increase of the local disorder suggesting an enhancement of the micellar core dynamics.
Effect of temperature and pressure to pinning centers in bulk MgB2 under high pressure
Authors: Kozyrev A.
Published: September 2014

The MgB2-based samples were synthesized at 2 GPa at 800 and 1050 °C for 1 h with and without Ti and SiC. X-ray, SEM and Auger structural studies showed that with increasing of manufacturing temperature grain boundary pinning transforms into point pinning, which is well correlated with the transformation of discontinuous oxygen enriched layers into separately located Mg–B–O inclusions in MgB2. Ti and SiC additions can influence the oxygen and boron distribution, but cannot change the type of pinning at relatively low temperatures.
Spatial confinement, self-polarization and exciton–phonon interaction effect on the location of exciton line in lead iodide nanofilms
Authors: Kramar V. M. , Pugantseva O. V. , Derevyanchuk A. V.
Published: September 2014

Theoretical investigation of the spatial confinement, self-polarization and exciton–phonon interaction influence on the exciton state in plane double nanoheterostructure (nanofilm)–lead iodide in polymeric matrix is performed within the effective mass approximation for the electron and dielectric continuum for the phonons in the framework of infinitely deep single quantum well. It is shown that spatial confinement is the dominating feature determining the energy of the bottom of exciton ground band and its binding energy. The relationship of two others depends on nanofilm thickness: in ultrathin films the influence of self-polarization effect is essentially bigger than the role of exciton–phonon interaction.
The interaction of 193 nm excimer laser radiation with single-crystal zinc oxide: Generation of long lived highly excited particles with evidence of Zn Rydberg formation
Authors: Khan Enamul H. , Langford S. C. , Dickinson J. T. , Boatner L. A.
Published: September 2014

In past studies, we have observed copious emissions of ionic and atomic Zn from single-crystal ZnO accompanying irradiation of single-crystal ZnO with 193-nm excimer laser irradiation at fluences below the onset of optical breakdown. The Zn+ and ground state Zn° are studied using time-of-flight techniques and are mass selected using a quadrupole mass spectrometer. Simultaneously, we have observed emitted particles that are detectable with a Channeltron electron multiplier but cannot be mass selected. It is a reasonable hypothesis that these particles correspond to a neutral atom or molecule in highly excited long lived states. We provide strong evidence that they correspond to high lying Rydberg states of atomic Zn. We propose a production mechanism involving laser excitation via a two photon resonance excitation of Zn°.
Quantum dynamical study of femtosecond photodesorption of CO from TiO2(110)
Authors: Asplund Erik , Klüner Thorsten
Published: September 2014

The photodesorption of CO from TiO2(110) by femtosecond pulses is investigated with the Surrogate Hamiltonian approach. The aim of the study is to resolve the relaxation mechanism and forecast the lifetime of the exited state based on a microscopic description of the excitation and relaxation processes. The parameters characterizing the system are obtained from ab initio and Density Functional Theory-calculations with one parameter estimated from physical considerations and convergence studies. Two electronic states are considered and the relaxation is assumed to be due to the interaction of the excited adsorbate with electron hole pairs in the surface. Desorption probabilities and velocity distributions of the desorbing molecules are calculated and an exited state lifetime is predicted. Throughout this paper atomic units, i.e., ℏ = me = e = a0 = 1, have been used unless otherwise stated.
On the nonlinear development of shear layers in partially vegetated channels
Authors: Lima A. C. , Izumi N.
Published: September 2014

A predictive theory is developed to investigate the nonlinear instability regime of perturbed shear layers in open-channel flows with lateral vegetation. The turbulence is characterized by two distinct scales: a sub-depth turbulence which is associated with the bed shear stress and a large-scale turbulence associated with the large horizontal eddies which develop in the shear layer. The sub-depth turbulence is modeled by assuming a logarithmic vertical distribution of the velocity. Meanwhile, an analogous model for the large-scale turbulence requires the estimation of the transverse velocity profile in the nonlinear state because the growth of the large-scale disturbances expands the shear layer and modifies the velocity distribution across the channel. The nonlinear growth of the disturbances is limited, however, because solid boundaries in the channel play stabilizing mechanisms which lock the amplitude of the large-scale disturbances into a finite-equilibrium state, for which a corresponding transverse velocity profile is determined. A weakly nonlinear stability analysis is performed and the results are validated using experimental data from previous works.
Accurate double many-body expansion potential energy surface for the 21A′ state of $\rm N_2O$N2O
Authors: Li Jing , Varandas António J. C.
Published: September 2014

An accurate double many-body expansion potential energy surface is reported for the 21A′ state of \documentclass[12pt]{minimal}\begin{document}$\rm N_2O$\end{document}N2O. The new double many-body expansion (DMBE) form has been fitted to a wealth of ab initio points that have been calculated at the multi-reference configuration interaction level using the full-valence-complete-active-space wave function as reference and the cc-pVQZ basis set, and subsequently corrected semiempirically via double many-body expansion-scaled external correlation method to extrapolate the calculated energies to the limit of a complete basis set and, most importantly, the limit of an infinite configuration interaction expansion. The topographical features of the novel potential energy surface are then examined in detail and compared with corresponding attributes of other potential functions available in the literature. Exploratory trajectories have also been run on this DMBE form with the quasiclassical trajectory method, with the thermal rate constant so determined at room temperature significantly enhancing agreement with experimental data.
On the self-propulsion of the euglenoid
Authors: Al-Housseiny Talal T.
Published: September 2014

We characterize the swimming speed of an euglenoid, which is propelled by large shape deformations traveling along its body.
Structural, electrical, and thermoelectric properties of bismuth telluride: Silicon/carbon nanocomposites thin films
Authors: Agarwal Khushboo , Mehta B. R.
Published: September 2014

In this study, the effect of the presence of secondary phases on the structural, electrical, and thermoelectric properties of nanocomposite Bi2Te3 films prepared by co-sputtering of silicon and carbon with Bi2Te3 has been investigated. Growth temperature and the presence of Si and C phase are observed to have a strong effect on the topography and orientation of crystallites. X-ray diffraction study demonstrates that Bi2Te3 and Bi2Te3:C samples have preferred (0 0 15) orientation in comparison to Bi2Te3:Si sample, which have randomly oriented crystallites. Atomic force, conducting atomic force, and scanning thermal microscopy analysis show significant differences in topographical, electrical, and thermal conductivity contrasts in Bi2Te3:Si and Bi2Te3:C samples. Due to the randomly oriented crystallites and the presence of Si along the crystallite boundaries, appreciable Seebeck coefficient, higher electrical conductivity, and lower thermal conductivity is achieved resulting in relatively higher value of power factor (3.71 mW K−2 m−1) for Bi2Te3:Si sample. This study shows that by incorporating a secondary phase along crystallite boundaries, microstructural, electrical, and thermoelectric properties of the composite samples can be modified.
Multi-dimensional modelling of electrostatic force distance curve over dielectric surface: Influence of tip geometry and correlation with experiment
Authors: Boularas A. , Baudoin F. , Villeneuve-Faure C. , Clain S. , Teyssedre G.
Published: September 2014

Electric Force-Distance Curves (EFDC) is one of the ways whereby electrical charges trapped at the surface of dielectric materials can be probed. To reach a quantitative analysis of stored charge quantities, measurements using an Atomic Force Microscope (AFM) must go with an appropriate simulation of electrostatic forces at play in the method. This is the objective of this work, where simulation results for the electrostatic force between an AFM sensor and the dielectric surface are presented for different bias voltages on the tip. The aim is to analyse force-distance curves modification induced by electrostatic charges. The sensor is composed by a cantilever supporting a pyramidal tip terminated by a spherical apex. The contribution to force from cantilever is neglected here. A model of force curve has been developed using the Finite Volume Method. The scheme is based on the Polynomial Reconstruction Operator—PRO-scheme. First results of the computation of electrostatic force for different tip–sample distances (from 0 to 600 nm) and for different DC voltages applied to the tip (6 to 20 V) are shown and compared with experimental data in order to validate our approach.
Contact research strategy for emerging molybdenum disulfide and other two-dimensional field-effect transistors
Authors: Du Yuchen , Yang Lingming , Liu Han , Ye Peide D.
Published: September 2014

Layered two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) have been widely isolated, synthesized, and characterized recently. Numerous 2D materials are identified as the potential candidates as channel materials for future thin film technology due to their high mobility and the exhibiting bandgaps. While many TMD filed-effect transistors (FETs) have been widely demonstrated along with a significant progress to clearly understand the device physics, large contact resistance at metal/semiconductor interface still remain a challenge. From 2D device research point of view, how to minimize the Schottky barrier effects on contacts thus reduce the contact resistance of metals on 2D materials is very critical for the further development of the field. Here, we present a review of contact research on molybdenum disulfide and other TMD FETs from the fundamental understanding of metal-semiconductor interfaces on 2D materials. A clear contact research strategy on 2D semiconducting materials is developed for future high-performance 2D FETs with aggressively scaled dimensions.
Cooperative spin freezing and the pinning assisted thermoremanent magnetization in Ni2.04Mn1.36Sn0.6 alloy
Authors: Pramanick S. , Chattopadhyay S. , Giri S. , Majumdar S. , Chatterjee S.
Published: September 2014

Detailed investigation on the ground-state magnetic properties of Ni2.04Mn1.36Sn0.6 alloy is reported. The sample undergoes martensitic type structural transformation from a cubic austenite phase to an orthorhombic martensite phase on cooling around TM = 220 K. It orders ferromagnetically just above room temperature with TC = 310 K. The phases above and below TM are predominantly ferromagnetic, although incipient antiferromagnetic correlations have been mooted between the Mn atoms sitting at two different crystallographic sites. The zero-field-cooled magnetic state shows a step like anomaly around TB = 100 K, and the sample is found to show clear signature of spin glass like behaviour below this point. It is also associated with considerable exchange bias effect below TB, where horizontal shift of isothermal magnetization loop is observed in the field-cooled state. Apart from exchange bias, there exists large thermoremanent magnetization. Interestingly, the thermoremanent magnetization obtained by cooling the sample from above and just below the first order martensitic transition failed to show any sizable change, which rules out any major role of field induced arrest across the first order transition. The observed thermoremanent magnetization is presumably due to the effect of pinning of uncompensated spins in this magnetically inhomogeneous system with random ferromagnetic as well as antiferromagnetic bonds on field cooling through the onset point (TB) of the spin-glass like state.
Effect of dynamic plastic deformation on the fluctuation stage of creep in single-crystal β-tin at 1.6 K
Authors: Kyrichenko G. I. , Soldatov V. P.
Published: September 2014

Plastic deformation is studied in single-crystal β-tin oriented for plastic slip in the (100) 〈010〉 system. Cases are examined in which the logarithmic low-temperature creep curves are preceded by dynamic movement of dislocations. For this purpose an attachment was developed for the deformation machine that made it possible to change the external load in a standard way over identical times on the order of 0.1 s. A computer was used to record the creep process with a time resolution of 0.04 s. The logarithmic creep coefficient α is found to decrease dramatically when the preceding dynamic component of the deformation increment is increased. Thus, correct study of low-temperature logarithmic creep and its mechanisms requires a correct choice of the experimental conditions that excludes the dynamic stage when possible.
A single metamaterial plate as bandpass filter, transparent wall, and polarization converter controlled by polarizations
Authors: Ma Hui Feng , Tang Wen Xuan , Cheng Qiang , Cui Tie Jun
Published: September 2014

We propose an anisotropic homogeneous metamaterial flat plate having multiple functionalities under different polarizations of incident waves. From the theoretical analysis based on Maxwell's equations, we demonstrate that a single one-dimensional anisotropic metamaterial slab with the tailored constitutive parameters serves as a bandpass filter, a transparent wall, and a polarization converter under illuminations of differently polarized waves. We present a special structural unit to realize the tailored constitutive parameter tensors of the anisotropic metamaterial from which a three-dimensional metamaterial flat plate is designed and fabricated. The measured results agree very well to theoretical calculations and full-wave simulations, demonstrating the excellent performance of the polarization-controlled multiple functionalities of the single metamaterial plate.
Communication: Charge, diffusion, and mobility of proteins through nanopores
Authors: Muthukumar M.
Published: September 2014

Implementation of Einstein's law connecting charge, diffusion coefficient, and mobility to interpret experimental data on proteins from single molecule electrophoresis through nanopores faces serious difficulties. The protein charge and diffusion coefficient, inferred with the Einstein law, can be orders of magnitude smaller than their bare values depending on the electrolyte concentration, pore diameter, chemical nature of the pore wall, and the externally applied voltage. The main contributors to the discrepancies are the coupled dynamics of the protein and its counterion cloud, confinement effects inside the pore, and the protein-pore-surface interaction. We have addressed these ingredients by harking on classical theories of electrophoresis of macroions and hydrodynamics inside pores, and deriving new results for pore-protein interactions. Putting together various components, we present approximate analytical formulas for the effective charge, diffusion coefficient, and mobility of a protein in the context of single molecule electrophoresis experiments. For the omnipresent pore-protein interactions, nonlinear dependence of the velocity of protein on voltage sets in readily and analytical formulas for this effect are presented. The derived formulas enable the determination of the bare charge and size of a protein from the experimentally measured apparent values.
Structural control of metamaterial oscillator strength and electric field enhancement at terahertz frequencies
Authors: Keiser G. R. , Seren H. R. , Strikwerda A. C. , Zhang X. , Averitt R. D.
Published: September 2014

The design of artificial nonlinear materials requires control over internal resonant charge densities and local electric field distributions. We present a MM design with a structurally controllable oscillator strength and local electric field enhancement at terahertz frequencies. The MM consists of a split ring resonator (SRR) array stacked above an array of closed conducting rings. An in-plane, lateral shift of a half unit cell between the SRR and closed ring arrays results in an increase of the MM oscillator strength by a factor of 4 and a 40% change in the amplitude of the resonant electric field enhancement in the SRR capacitive gap. We use terahertz time-domain spectroscopy and numerical simulations to confirm our results. We show that the observed electromagnetic response in this MM is the result of image charges and currents induced in the closed rings by the SRR.
Influence of vicinal sapphire substrate on the properties of N-polar GaN films grown by metal-organic chemical vapor deposition
Authors: Lin Zhiyu , Zhang Jincheng , Xu Shengrui , Chen Zhibin , Yang Shuangyong , Tian Kun , Su Xujun , Shi Xuefang , Hao Yue
Published: September 2014

The influence of vicinal sapphire substrates on the growth of N-polar GaN films by metal-organic chemical vapor deposition is investigated. Smooth GaN films without hexagonal surface feature are obtained on vicinal substrate. Transmission electron microscope results reveal that basal-plane stacking faults are formed in GaN on vicinal substrate, leading to a reduction in threading dislocation density. Furthermore, it has been found that there is a weaker yellow luminescence in GaN on vicinal substrate than that on (0001) substrate, which might be explained by the different trends of the carbon impurity incorporation.
Compact electro-absorption modulator integrated with vertical-cavity surface-emitting laser for highly efficient millimeter-wave modulation
Authors: Dalir Hamed , Ahmed Moustafa , Bakry Ahmed , Koyama Fumio
Published: September 2014

We demonstrate a compact electro-absorption slow-light modulator laterally-integrated with an 850 nm vertical-cavity surface-emitting laser (VCSEL), which enables highly efficient millimeter-wave modulation. We found a strong leaky travelling wave in the lateral direction between the two cavities via widening the waveguide width with a taper shape. The small signal response of the fabricated device shows a large enhancement of over 55 dB in the modulation amplitude at frequencies beyond 35 GHz; thanks to the photon-photon resonance. A large group index of over 150 in a Bragg reflector waveguide enables the resonance at millimeter wave frequencies for 25 μm long compact modulator. Based on the modeling, we expect a resonant modulation at a higher frequency of 70 GHz. The resonant modulation in a compact slow-light modulator plays a significant key role for high efficient narrow-band modulation in the millimeter wave range far beyond the intrinsic modulation bandwidth of VCSELs.
A battery material charges via an unexpected mechanism
Authors: Miller Johanna L.
Published: September 2014

Time-resolved x-ray diffraction experiments help to explain why lithium iron phosphate cathodes work so well.
Report urges more planning to cope with Fukushima-like event
Authors: Kramer David
Published: September 2014

Industry and the NRC maintain that US reactor safety has greatly improved in the three years since Japan’s nuclear catastrophe.
What we know and don’t know about tornado formation
Authors: Markowski Paul , Richardson Yvette
Published: September 2014

Forecasters would love to predict violent weather with more accuracy and longer lead times. Researchers are helping them by unraveling the science behind the complex sequence of events that lead to tornadoes.
Exotic particles with four or more quarks
Authors: Olsen Stephen Lars
Published: September 2014

The familiar denizens of the particle zoo are made of two or three quarks, but particle theory allows for states comprising any number of those fundamental particles. Finally, after decades of searching, tetraquarks seem to have been spotted.
Development of mathematical models to predict volume and nutrient composition of fresh manure from lactating Holstein cows
Authors: Appuhamy J. A. D. Ranga Niroshan , Moraes L. E. , Wagner-Riddle C. , Casper D. P. , France J. , Kebreab E.
Published: September 2014

Organic compounds in dairy manure undergo a series of reactions producing pollutants such as ammonia and methane. Because various organic compounds have different reaction rates, the emissions could be accurately determined if amounts and concentrations of individual nutrients in manure are known. A set of empirical models were developed for predicting faecal and urinary water, carbon (C), nitrogen (N), acid detergent fibre and neutral detergent fibre output (kg/day) from lactating Holstein cows. Dietary nutrient contents, milk yield and composition, bodyweight, age and days in milk were used with or without dry matter intake (DMI) as potential predictor variables. Multi-collinearity, goodness of fit, model complexity, and random study and animal effects were taken into account during model development, which used 742 measured faecal or urinary nutrient output observations (kg/day). The models were evaluated with an independent dataset (n = 364). When DMI was used as a predictor variable, the models predicted faecal and urinary nutrient outputs successfully with root mean square prediction error as a percentage of average observed values (RMSPE%) ranging from 9.1% to 20.7%. All the predictions except urine output had RMSPE% ranging from 18.3% to 24.6% when DMI was not used. The nutrient output predictions were in reasonable agreement with observed values throughout the data range (systematic bias <14% of total bias). Fresh manure C : N ratio predictions were acceptable (RMSPE% = 14.3–15.2%) although the systematic bias were notable (17.1–20.7% of total bias). The models could be integrated successfully with process-based manure or soil models to assess nutrient transformation in dairy production systems.
Development of the BeefSpecs fat calculator to assist decision making to increase compliance rates with beef carcass specifications
Authors: Walmsley B. J. , McPhee M. J. , Oddy V. H.
Published: September 2014

The BeefSpecs fat calculator is a decision-support system developed to assist decision making on-farm to improve compliance rates with beef carcass specifications. BeefSpecs is underpinned by a research model run in conjunction with a translation process that converts inputs recorded in live animal and carcass assessment language into research model parameters. In contrast to many other research modelling systems, the changes in body composition predicted by the research model that underpins BeefSpecs are driven by growth rate. Use of this model removes the need for information concerning feed intake and dietary characteristics, which are impractical to collect on a routine basis in commercial production systems. A translation process was developed to use traits that are recorded routinely on-farm during normal production activities while allowing the original modelling system to run efficiently and accurately. This process aligns BeefSpecs with the language used by industry and increases the confidence of users in the underlying model theories. The outputs produced by BeefSpecs include final liveweight, final subcutaneous fat depth and hot standard carcass weight at the end of a specified feeding period. These traits contribute to the carcass specifications used to determine carcass value in the domestic and international markets supplied by the Australian beef industry, which directly aligns BeefSpecs with the decision-making styles of beef producers. During the development of BeefSpecs, potential users were consulted and enlisted in the evaluation process.
Intra-host mathematical models of malaria.
Authors: Santos G. , Torres N. V.
Published: September 2014

Mathematical modelling of intra-host malaria is a relatively recent topic. Although the first mathematical model related to malaria was proposed by Sir Ronald Ross in 1915, the first attempt to model the parasite-host interactions was as recent as 1989. Since then, a moderate but steadily growing number of articles dealing with this topic have been published, including a couple of reviews. In this review, we aim to sum up the knowledge that this particular mathematical modelling approach has provided with respect to the role played by
Plasmodium
in infection mechanisms.
Genetic evidence for the role of plasmacytoid dendritic cells in systemic lupus erythematosus
Authors: Sisirak Vanja , Ganguly Dipyaman , Lewis Kanako L. , Couillault Coline , Tanaka Lena , Bolland Silvia , D’Agati Vivette , Elkon Keith B. , Reizis Boris
Published: September 2014

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by the production of antibodies to self-nucleic acids, immune complex deposition, and tissue inflammation such as glomerulonephritis. Innate recognition of self-DNA and -RNA and the ensuing production of cytokines such as type I interferons (IFNs) contribute to SLE development. Plasmacytoid dendritic cells (pDCs) have been proposed as a source of pathogenic IFN in SLE; however, their net contribution to the disease remains unclear. We addressed this question by reducing gene dosage of the pDC-specific transcription factor E2-2 (Tcf4), which causes a specific impairment of pDC function in otherwise normal animals. We report that global or DC-specific Tcf4 haplodeficiency ameliorated SLE-like disease caused by the overexpression of the endosomal RNA sensor Tlr7. Furthermore, Tcf4 haplodeficiency in the B6.Sle1.Sle3 multigenic model of SLE nearly abolished key disease manifestations including anti-DNA antibody production and glomerulonephritis. Tcf4-haplodeficient SLE-prone animals showed a reduction of the spontaneous germinal center reaction and its associated gene expression signature. These results provide genetic evidence that pDCs are critically involved in SLE pathogenesis and autoantibody production, confirming their potential utility as therapeutic targets in the disease.
Early, transient depletion of plasmacytoid dendritic cells ameliorates autoimmunity in a lupus model
Authors: Rowland Sarah L. , Riggs Jeffrey M. , Gilfillan Susan , Bugatti Mattia , Vermi William , Kolbeck Roland , Unanue Emil R. , Sanjuan Miguel A. , Colonna Marco
Published: September 2014

Plasmacytoid dendritic cells (pDCs) have long been implicated in the pathogenesis of lupus. However, this conclusion has been largely based on a correlative link between the copious production of IFN-α/β by pDCs and the IFN-α/β “signature” often seen in human lupus patients. The specific contribution of pDCs to disease in vivo has not been investigated in detail. For this reason, we generated a strain of BXSB lupus-prone mice in which pDCs can be selectively depleted in vivo. Early, transient ablation of pDCs before disease initiation resulted in reduced splenomegaly and lymphadenopathy, impaired expansion and activation of T and B cells, reduced antibodies against nuclear autoantigens and improved kidney pathology. Amelioration of pathology coincided with decreased transcription of IFN-α/β–induced genes in tissues. PDC depletion had an immediate impact on the activation of immune cells, and importantly, the beneficial effects on pathology were sustained even though pDCs later recovered, indicating an early pDC contribution to disease. Together, our findings demonstrate a critical function for pDCs during the IFN-α/β–dependent initiation of autoimmune lupus and point to pDCs as an attractive therapeutic target for the treatment of SLE.
Deciphering the Components That Coordinately Regulate Virulence Factors of the Soft Rot Pathogen Dickeya dadantii
Authors: Wu Xiaogang , Zeng Quan , Koestler Benjamin J. , Waters Christopher M. , Sundin George W. , Hutchins William , Yang Ching-Hong
Published: September 2014

The bacterial soft rot pathogen Dickeya dadantii utilizes the type III secretion system (T3SS) to suppress host defense responses, and secretes pectate lyase (Pel) to disintegrate the plant cell wall. A transposon mutagenesis fluorescence-activated cell sorting screen was used to identify mutants with altered promoter activities of the T3SS pilus gene hrpA. Several insertion mutations, resulting in changes in hrpA expression, were mapped to a new locus, opgGH, which encodes the gene cluster responsible for osmoregulated periplasmic glucan (OPG) synthesis proteins. Our data showed that OPG was involved in T3SS and Pel regulation by altering the expression of the regulatory small RNA RsmB. Through genome searching, the mechanism of two novel regulatory components, the RcsCD-RcsB phosphorelay and CsrD on OPG and the rsmB gene, was further investigated. The Rcs phosphorelay and OPG inversely regulated rsmB at transcriptional and post-transcriptional levels, respectively. CsrD exhibited dual functionality in T3SS and Pel regulation by manipulating levels of RsmB RNA and cyclic diguanylate monophosphate (c-di-GMP). CsrD positively regulated the promoter activity of the rsmB gene but negatively controlled RsmB RNA at the post-transcriptional level via OpgGH. In addition, CsrD contains both GGDEF and EAL domains but acted as a c-di-GMP phosphodiesterase. When the expression of the csrD gene was induced, CsrD regulated T3SS expression and Pel production through controlling intracellular c-di-GMP levels.
Perspective: network-guided pattern formation of neural dynamics
Authors: Hütt Marc-Thorsten , Kaiser Marcus , Hilgetag Claus C.
Published: September 2014

The understanding of neural activity patterns is fundamentally linked to an understanding of how the brain's network architecture shapes dynamical processes. Established approaches rely mostly on deviations of a given network from certain classes of random graphs. Hypotheses about the supposed role of prominent topological features (for instance, the roles of modularity, network motifs or hierarchical network organization) are derived from these deviations. An alternative strategy could be to study deviations of network architectures from regular graphs (rings and lattices) and consider the implications of such deviations for self-organized dynamic patterns on the network. Following this strategy, we draw on the theory of spatio-temporal pattern formation and propose a novel perspective for analysing dynamics on networks, by evaluating how the self-organized dynamics are confined by network architecture to a small set of permissible collective states. In particular, we discuss the role of prominent topological features of brain connectivity, such as hubs, modules and hierarchy, in shaping activity patterns. We illustrate the notion of network-guided pattern formation with numerical simulations and outline how it can facilitate the understanding of neural dynamics.
An edge-centric perspective on the human connectome: link communities in the brain
Authors: de Reus Marcel A. , Saenger Victor M. , Kahn René S. , van den Heuvel Martijn P.
Published: September 2014

Brain function depends on efficient processing and integration of information within a complex network of neural interactions, known as the connectome. An important aspect of connectome architecture is the existence of community structure, providing an anatomical basis for the occurrence of functional specialization. Typically, communities are defined as groups of densely connected network nodes, representing clusters of brain regions. Looking at the connectome from a different perspective, instead focusing on the interconnecting links or edges, we find that the white matter pathways between brain regions also exhibit community structure. Eleven link communities were identified: five spanning through the midline fissure, three through the left hemisphere and three through the right hemisphere. We show that these link communities are consistently identifiable and investigate the network characteristics of their underlying white matter pathways. Furthermore, examination of the relationship between link communities and brain regions revealed that the majority of brain regions participate in multiple link communities. In particular, the highly connected and central hub regions showed a rich level of community participation, supporting the notion that these hubs play a pivotal role as confluence zones in which neural information from different domains merges.
Mapping human brain networks with cortico-cortical evoked potentials
Authors: Keller Corey J. , Honey Christopher J. , Mégevand Pierre , Entz Laszlo , Ulbert Istvan , Mehta Ashesh D.
Published: September 2014

The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex.