bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase‐locked loops redesign by the Lyapunov theory
Authors: Rahmani M. , Nodozi I.
Published: October 2015

A new approach is proposed to design a phase‐locked loop (PLL) as an adaptive system in order to extract the desired sinusoidal component of the input signal, and estimate its amplitude and phase. In this method, the Lyapunov stability theorem is used to obtain adjustment rules for parameters, i.e. the stability of the system and convergence of the parameters are guaranteed in the sense of Lyapunov. Simulation results show the effectiveness of the proposed structure, and demonstrate that the input signal level and adaptation gains do not change the performance of the system. The proposed PLL structure can be utilised for fast and accurate applications in signal processing, power electronics, communication systems, and control.
Theoretical lower bound on average periodic partial Hamming correlations of frequency‐hopping sequence set
Authors: Zhou Limengnan , Peng Daiyuan
Published: October 2015

Owing to the limited synchronisation time and hardware complexity of frequency‐hopping multiple access (FHMA) systems, partial Hamming correlation of the frequency‐hopping sequence (FHS) set applied by the FHMA system plays an increasingly important role in measuring the performance of the system. A new lower bound on the average periodic partial Hamming correlation which is tighter than the existing one in a particular case is introduced. The new lower bound includes some earlier theoretical lower bounds on the average Hamming correlation of the FHS set as special cases. A necessary and sufficient condition for obtaining optimality with regard to the new bound is also presented.
Observation of zero linewidth enhancement factor at excited state band in quantum dot laser
Authors: Zubov F.I. , Maximov M.V. , Moiseev E.I. , Savelyev A.V. , Shernyakov Y.M. , Livshits D.A. , Kryzhanovskaya N.V. , Zhukov A.E.
Published: October 2015

The linewidth enhancement factor (LEF) of an InAs/InGaAs quantum dot Fabry‐Pérot laser in a wide wavelength range from 1110 to 1300 nm, including ground state (GS) and exited state (ES) bands, is studied. LEF spectra were derived from amplified spontaneous emission spectra measured below the threshold in the pulse regime. The ES optical transition is characterised by significantly lower values of the LEF (≤0.54) as compared to the GS (≥1.21). Moreover, a zero LEF is observed within the ES spectral band. At sufficiently high currents, a near‐zero LEF (|α| ≤ 0.1) is achieved in a wide spectral interval from 1146 to 1175 nm, in which the optical gain is not less than 9 cm−1.
Prediction of vacuum cleaner motor brush life: a regression approach
Authors: Benedik Blaž , Taškova Katerina , Tavčar Jože , Duhovnik Jože
Published: October 2015

The main focus of this paper is the empirical modelling of the wear of carbon brushes. Rather than determining the dominant wear mechanisms, an approach towards the prediction of wear under a range of different conditions was used. The models were obtained by multiple regression analysis using lifetime (LT) data contributed by the biggest European manufacturer of vacuum cleaner motors. This included reliability data for 607 different test populations involving 3980 motors. Exploration of the data revealed that wear‐out parameters behaved in accordance with the existing field theory, giving additional confidence to the models. The numerical appreciation of the wear‐out parameters and the resulting conclusions will be beneficial to motor design and reliability engineers. Learned knowledge will be used for faster selection of optimal design and operational motor parameters to meet recent EU regulation 666/2013. Along with the more rapid design of the product, a reduced number of LT tests will result in significant energy savings.
Data and pilot optimised combining method for new composite global navigation satellite system signal acquisition
Authors: Jianlei Yang , Tian Jin , Zhigang Huang , Honglei Qin , Rui Xue
Published: October 2015

With the increasing adoption of high bit rate navigation signals, the performance of detection is significantly affected by sign transition. To reduce the correlation loss caused by the sign transition, three optimised channel combining methods, which include the optimised non‐coherent channel combining, optimised coherent channel combining and optimised differential channel combining, are proposed in this study. Three corresponding analytical expressions of probabilities of detection for the authors methods are derived. To better evaluate the performance of their methods, three corresponding analytical expressions of probabilities of detection for conventional channel combining methods in the presence of sign transition are also derived. Comparing with conventional channel combining and zero padding methods, although increasing the computational cost, their methods can achieve 2–2.5 and 4–6 dB acquisition sensitivity improvements according to the analytic and simulated results. Moreover, experiments on real data from global positioning system L5 further evaluate the detection performance of their methods.
Integral group actions on symmetric spaces and discrete duality symmetries of supergravity theories
Authors: Carbone Lisa , Murray Scott H. , Sati Hisham
Published: October 2015

For G = G(ℝ), a split, simply connected, semisimple Lie group of rank n and K the maximal compact subgroup of G, we give a method for computing Iwasawa coordinates of K∖G using the Chevalley generators and the Steinberg presentation. When K∖G is a scalar coset for a supergravity theory in dimensions ≥3, we determine the action of the integral form G(ℤ) on K∖G. We give explicit results for the action of the discrete U-duality groups SL2(ℤ) and E7(ℤ) on the scalar cosets SO(2)∖SL2(ℝ) and [SU(8)/{ ± Id}]∖E7(+7)(ℝ) for type IIB supergravity in ten dimensions and 11-dimensional supergravity reduced to D = 4 dimensions, respectively. For the former, we use this to determine the discrete U-duality transformations on the scalar sector in the Borel gauge and we describe the discrete symmetries of the dyonic charge lattice. We determine the spectrum-generating symmetry group for fundamental BPS solitons of type IIB supergravity in D = 10 dimensions at the classical level and we propose an analog of this symmetry at the quantum level. We indicate how our methods can be used to study the orbits of discrete U-duality groups in general.
The Landau–Lifshitz equation in atomistic models
Authors: Ellis M. O. A. , Evans R. F. L. , Ostler T. A. , Barker J. , Atxitia U. , Chubykalo-Fesenko O. , Chantrell R. W.
Published: October 2015

The Landau–Lifshitz (LL) equation, originally proposed at the macrospin level, is increasingly used in Atomistic Spin Dynamic (ASD) models. These models are based on a spin Hamiltonian featuring atomic spins of fixed length, with the exchange introduced using the Heisenberg formalism. ASD models are proving a powerful approach to the fundamental understanding of ultrafast magnetization dynamics, including the prediction of the thermally induced magnetization switching phenomenon in which the magnetization is reversed using an ultra-fast laser pulse in the absence of an externally applied field. This paper outlines the ASD model approach and considers the role and limitations of the LL equation in this context.
A simple method for finding the scattering coefficients of quantum graphs
Authors: Cottrell Seth S.
Published: October 2015

Quantum walks are roughly analogous to classical random walks, and similar to classical walks they have been used to find new (quantum) algorithms. When studying the behavior of large graphs or combinations of graphs, it is useful to find the response of a subgraph to signals of different frequencies. In doing so, we can replace an entire subgraph with a single vertex with variable scattering coefficients. In this paper, a simple technique for quickly finding the scattering coefficients of any discrete-time quantum graph will be presented. These scattering coefficients can be expressed entirely in terms of the characteristic polynomial of the graph’s time step operator. This is a marked improvement over previous techniques which have traditionally required finding eigenstates for a given eigenvalue, which is far more computationally costly. With the scattering coefficients we can easily derive the “impulse response” which is the key to predicting the response of a graph to any signal. This gives us a powerful set of tools for rapidly understanding the behavior of graphs or for reducing a large graph into its constituent subgraphs regardless of how they are connected.
Line mixing in parallel and perpendicular bands of CO2: A further test of the refined Robert-Bonamy formalism
Authors: Boulet C. , Ma Q. , Tipping R. H.
Published: October 2015

Starting from the refined Robert-Bonamy formalism [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)], we propose here an extension of line mixing studies to infrared absorptions of linear polyatomic molecules having stretching and bending modes. The present formalism does not neglect the internal degrees of freedom of the perturbing molecules, contrary to the energy corrected sudden (ECS) modelling, and enables one to calculate the whole relaxation matrix starting from the potential energy surface. Meanwhile, similar to the ECS modelling, the present formalism properly accounts for roles played by all the internal angular momenta in the coupling process, including the vibrational angular momentum. The formalism has been applied to the important case of CO2 broadened by N2. Applications to two kinds of vibrational bands (Σ → Σ and Σ → Π) have shown that the present results are in good agreement with both experimental data and results derived from the ECS model.
Flow patterning in Hele-Shaw configurations using non-uniform electro-osmotic slip
Authors: Boyko Evgeniy , Rubin Shimon , Gat Amir D. , Bercovici Moran
Published: October 2015

We present an analytical study of electro-osmotic flow in a Hele-Shaw configuration with non-uniform zeta potential distribution. Applying the lubrication approximation and assuming thin electric double layer, we obtain a pair of uncoupled Poisson equations for the pressure and depth-averaged stream function, and show that the inhomogeneous parts in these equations are governed by gradients in zeta potential parallel and perpendicular to the applied electric field, respectively. We obtain a solution for the case of a disk-shaped region with uniform zeta potential and show that the flow field created is an exact dipole, even in the immediate vicinity of the disk. In addition, we study the inverse problem where the desired flow field is known and solve for the zeta potential distribution required in order to establish it. Finally, we demonstrate that such inverse problem solutions can be used to create directional flows confined within narrow regions, without physical walls. Such solutions are equivalent to flow within channels and we show that these can be assembled to create complex microfluidic networks, composed of intersecting channels and turns, which are basic building blocks in microfluidic devices.
Magnetization dynamics induced by femtosecond light pulses
Authors: Kimel A. V. , Zvezdin A. K.
Published: October 2015

Work on magnetization dynamics induced by femtosecond light pulses is reviewed. It is shown that the effect of ultrashort light pulses on spins can be represented as the effect of an effective magnetic field. Thus, optically-induced magnetization dynamics can be described by the Landau-Lifshitz equation.
Unitary symmetry and generalization of the Landau–Lifshitz equation for high-spin magnets
Authors: Kovalevsky M. Y.
Published: October 2015

The dynamics of magnetic materials with arbitrary spin is described. The relations between the pure and mixed quantum states with magnetic degrees of freedom are considered. Nonlinear dynamic equations of normal and degenerate nonequilibrium states of high-spin magnets are obtained. We analyze in detail the subalgebras of the Poisson brackets of magnetic quantities for the cases of magnets with spin s = 1/2, 1, and 3/2, in which the exchange interaction has the properties of SO(3), SU(3), SU(4), SU(2), SU(2), SO(4), and SO(5) symmetries. An explicit form of the polarization density matrix for the magnets with spin s = 1 and s = 3/2 in pure quantum states is derived and the range of allowed values of the magnetic degrees of freedom for mixed states is found.
Relaxation of magnetic systems after sudden magnetic field changes
Authors: Zvyagin A. A.
Published: October 2015

In magnetic systems where the projection of the total spin moment of the system parallel to an external magnetic field is not conserved, a sudden change in the field produces oscillations in the magnetization. The amplitude and frequency of these oscillations depend nonlinearly on the change in the field. Landau-Lifshitz relaxation in the magnetic system leads to a nonlinear dependence of the amplitude and frequency of the oscillations on the relaxation parameter, as well as to a dependence of the damping rate on the energy parameters of the magnet and on the amplitude of the jump in the external magnetic field.
Nonlinear forecasting of intertidal shoreface evolution
Authors: Grimes D. J. , Cortale N. , Baker K. , McNamara D. E.
Published: October 2015

Natural systems dominated by sediment transport are notoriously difficult to forecast. This is particularly true along the ocean coastline, a region that draws considerable human attention as economic investment and infrastructure are threatened by both persistent, long-term and acute, event driven processes (i.e., sea level rise and storm damage, respectively). Forecasting the coastline's evolution over intermediate time (daily) and space (tens of meters) scales is hindered by the complexity of sediment transport and hydrodynamics, and limited access to the detailed local forcing that drives fast scale processes. Modern remote sensing systems provide an efficient, economical means to collect data within these regions. A solar-powered digital camera installation is used to capture the coast's evolution, and machine learning algorithms are implemented to extract the shoreline and estimate the daily mean intertidal coastal profile. Methods in nonlinear time series forecasting and genetic programming applied to these data corroborate that coastal morphology at these scales is predominately driven by nonlinear internal dynamics, which partially mask external forcing signatures. Results indicate that these forecasting techniques achieve nontrivial predictive skill for spatiotemporal forecast of the upper coastline profile (as much as 43% of variance in data explained for one day predictions). This analysis provides evidence that societally relevant coastline forecasts can be achieved without knowing the forcing environment or the underlying dynamical equations that govern coastline evolution.
A first-principle calculation of the XANES spectrum of Cu2+ in water
Authors: La Penna G. , Minicozzi V. , Morante S. , Rossi G. C. , Stellato F.
Published: October 2015

The progress in high performance computing we are witnessing today offers the possibility of accurate electron density calculations of systems in realistic physico-chemical conditions. In this paper, we present a strategy aimed at performing a first-principle computation of the low energy part of the X-ray Absorption Spectroscopy (XAS) spectrum based on the density functional theory calculation of the electronic potential. To test its effectiveness, we apply the method to the computation of the X-ray absorption near edge structure part of the XAS spectrum in the paradigmatic, but simple case of Cu2+ in water. In order to keep into account the effect of the metal site structure fluctuations in determining the experimental signal, the theoretical spectrum is evaluated as the average over the computed spectra of a statistically significant number of simulated metal site configurations. The comparison of experimental data with theoretical calculations suggests that Cu2+ lives preferentially in a square-pyramidal geometry. The remarkable success of this approach in the interpretation of XAS data makes us optimistic about the possibility of extending the computational strategy we have outlined to the more interesting case of molecules of biological relevance bound to transition metal ions.
An eight-dimensional quantum dynamics study of the Cl + CH4→ HCl + CH3 reaction
Authors: Liu Na , Yang Minghui
Published: October 2015

In this work, the later-barrier reaction Cl + CH4 → HCl + CH3 is investigated with an eight-dimensional quantum dynamics method [R. Liu et al., J. Chem. Phys. 137, 174113 (2012)] on the ab initio potential energy surface of Czakó and Bowman [J. Chem. Phys. 136, 044307 (2012)]. The reaction probabilities with CH4 initially in its ground and vibrationally excited states are calculated with a time-dependent wavepacket method. The theoretical integral cross sections (ICSs) are extensively compared with the available experimental measurements. For the ground state reaction, the theoretical ICSs excellently agree with the experimental ones. The good agreements are also achieved for ratios between ICSs of excited reactions. For ICS ratios between various states, the theoretical values are also consistent with the experimental observations. The rate constants over 200-2000 K are calculated and the non-Arrhenius effect has been observed which is coincident with the previous experimental observations and theoretical calculations.
Epitaxial manganite freestanding bridges for low power pressure sensors
Authors: Le Bourdais D. , Agnus G. , Maroutian T. , Pillard V. , Aubert P. , Bachelet R. , Saint-Girons G. , Vilquin B. , Lefeuvre E. , Lecoeur P.
Published: October 2015

The highly temperature-dependent resistivity of the La2/3Sr1/3MnO3 (LSMO) manganite is taken as an advantage in a pressure sensor design based on the Pirani effect. Thin epitaxial films are grown on silicon substrate thanks to a SrTiO3 buffer layer that allows the fabrication of freestanding bridges by means of clean-room processes. The devices are then heated by Joule effect and their temperature modulated by heat transfer through the surrounding gas. The higher the current flowing in the bridge, the larger the resistance variation with pressure is, due to the Pirani effect. The heating current and device geometry are tuned in order to stay in a monotonous regime, avoiding the change of sign of the LSMO temperature coefficient. A sensitivity increased by a factor of 3 and a power consumption reduced by 5 orders of magnitude are measured by comparing oxide devices with conventional metallic ones of same geometry.
Full-zone spectral envelope function formalism for the optimization of line and point tunnel field-effect transistors
Authors: Verreck Devin , Verhulst Anne S. , Van de Put Maarten , Sorée Bart , Magnus Wim , Mocuta Anda , Collaert Nadine , Thean Aaron , Groeseneken Guido
Published: October 2015

Efficient quantum mechanical simulation of tunnel field-effect transistors (TFETs) is indispensable to allow for an optimal configuration identification. We therefore present a full-zone 15-band quantum mechanical solver based on the envelope function formalism and employing a spectral method to reduce computational complexity and handle spurious solutions. We demonstrate the versatility of the solver by simulating a 40 nm wide In0.53Ga0.47As lineTFET and comparing it to p-n-i-n configurations with various pocket and body thicknesses. We find that the lineTFET performance is not degraded compared to semi-classical simulations. Furthermore, we show that a suitably optimized p-n-i-n TFET can obtain similar performance to the lineTFET.
High power cascaded mid-infrared InAs/GaSb light emitting diodes on mismatched GaAs
Authors: Provence S. R. , Ricker R. , Aytac Y. , Boggess T. F. , Prineas J. P.
Published: October 2015

InAs/GaSb mid-wave, cascaded superlattice light emitting diodes are found to give higher radiance when epitaxially grown on mismatched GaAs substrates compared to lattice-matched GaSb substrates. Peak radiances of 0.69 W/cm2-sr and 1.06 W/cm2-sr for the 100 × 100 μm2 GaSb and GaAs-based devices, respectively, were measured at 77 K. Measurement of the recombination coefficients shows the shorter Shockley-Read-Hall recombination lifetime as misfit dislocations for growth on GaAs degrade the quantum efficiency only at low current injection. The improved performance on GaAs was found to be due to the higher transparency and improved thermal properties of the GaAs substrate.
Splash jet and slamming generated by a rotating flap
Authors: Sun S. Y. , Sun S. L. , Ren H. L. , Wu G. X.
Published: October 2015

The hydrodynamic problem of slamming generated by a rotating flap, commonly known as Oyster in the wave energy sector, plunging into water, is analysed based on the incompressible velocity potential theory. The problem is solved through the boundary element method in the time domain. Two typical case studies are undertaken. One is the flap plunging into calm water and the other into an incoming wave. The splash jet formed during the flap plunging is included in the simulation. When the jet meets the main flow, it is treated through the domain decomposition method without taking account the secondary impact, which is similar to the mathematical method of Riemann’s second sheet in the complex plane. The problem is solved in each non-overlapping subdomain, and the velocity and pressure continuity condition is imposed on the interface of the subdomains. Detailed results for the flap plunging into water with different velocities or accelerations are provided. The gravity and wave effects are also investigated.
Strain-mediated magnetic and transport properties of epitaxial LuxFe3−xO4 films
Authors: Wang P. , Jin C. , Zheng D. X. , Bai H. L.
Published: October 2015

Strain mediated structure, magnetic, and transport properties of spinel ferrites were investigated by growing epitaxial LuxFe3−xO4 (LFO, 0≤x≤0.26) films on SrTiO3 and MgO substrates with in-plane compressive and tensile strains, respectively. The lattice parameter of LFO films decreases on SrTiO3 substrates, while increases on MgO substrates with the increasing Lu content. The LFO films on SrTiO3 substrates exhibit larger saturation magnetization and smaller exchange bias and coercive field. Phase shift of anisotropic magnetoresistance is also observed in the LFO films on SrTiO3 substrates. In addition, the nonmagnetic Lu3+ ions in spinel ferrites enhance the spin canting, which further increases the exchange bias and coercive field and strengthens the four-fold symmetry of anisotropic magnetoresistance and the two-fold symmetry of planar Hall effect.
Kinetic Alfven solitary waves in a magnetized plasma with superthermal electrons
Authors: Panwar A. , Ryu C. M. , Bains A. S.
Published: October 2015

A study of the ion Larmor radius effects on the solitary kinetic Alfven waves (SKAWs) in a magnetized plasma with superthermal electrons is presented by employing the kinetic theory. The linear dispersion relation of SKAW is shown to depend on the superthermal parameter κ, ion to electron temperature ratio, and the angle of wave propagation. Using the Sagdeev potential approach, the energy balance equation has been derived to study the dynamics of SKAWs. The effects of various plasma parameters are investigated for the propagation of SKAWs. It is shown that only compressive solitons can exist and in the Maxwellian limit our results are in good agreement with previous studies. Further, the characteristics of small amplitude SKAWs are investigated. Present study could be useful for the understanding of SKAWs in a low β plasma in astrophysical environment, where particle distributions are superthermal in nature.
Linear theory of low frequency magnetosonic instabilities in counterstreaming bi-Maxwellian plasmas
Authors: Vafin S. , Schlickeiser R. , Yoon P. H.
Published: October 2015

An effect of the bi-Maxwellian counterstreaming distribution function is analyzed with regard to the linear low frequency instabilities in magnetized homogeneous collisionless plasmas. New analytical marginal instability conditions for the firehose and the mirror modes have been obtained. Presence of counterstreams along the ambient magnetic field causes a huge effect on the instability conditions of those modes. The instability conditions very sensitively depend on the functional dependence of the counterstreaming parameter P. The theoretically predicted results might give a full potential explanation for the observed solar wind temperature anisotropy diagram in A-β∥ plane [S. D. Bale et al., Phys. Rev. Lett. 103, 211101 (2009)].
How noise affects quantum detector tomography
Authors: Wang Q. , Renema J. J. , Gaggero A. , Mattioli F. , Leoni R. , van Exter M. P. , de Dood M. J. A.
Published: October 2015

We determine the full photon number response of a NbN superconducting nanowire single photon detector via quantum detector tomography, and the results show the separation of linear, effective absorption efficiency from the internal detection efficiencies. In addition, we demonstrate an error budget for the complete quantum characterization of the detector. We find that for short times, the dominant noise source is shot noise, while laser power fluctuations limit the accuracy for longer timescales. The combined standard uncertainty of the internal detection efficiency derived from our measurements is about 2%.
Microstructure and transport properties of epitaxial topological insulator Bi2Se3 thin films grown on MgO (100), Cr2O3 (0001), and Al2O3 (0001) templates
Authors: Lee Y. F. , Kumar R. , Hunte F. , Narayan J. , Schwartz J.
Published: October 2015

We report the epitaxial integration of defect-induced room temperature ferromagnetic insulators, Cr2O3 and MgO, with topological insulators Bi2Se3 on c-sapphire substrate by pulsed laser deposition. The structural, magnetic, and magnetotransport properties of ∼15 nm Bi2Se3 thin films are investigated on each template. The lattice misfits of Cr2O3/Bi2Se3 and MgO/Bi2Se3 are ∼16% and ∼39%, respectively, where the critical thickness for pseudomorphic growth is less than one monolayer. The insulating behavior is more pronounced due to the additional scattering of the surface states of the Bi2Se3 layer by interfacing with MgO and Cr2O3. The weak antilocalization effect from the surface states is clearly suppressed, accounting for the presence of magnetic bottom layers. This work demonstrates an effective way to study the emergence of a ferromagnetic phase in topological insulators by the magnetic proximity effect in Bi2Se3, a step toward unveiling their exotic properties.
Electrostatic point charge fitting as an inverse problem: Revealing the underlying ill-conditioning
Authors: Ivanov Maxim V. , Talipov Marat R. , Timerghazin Qadir K.
Published: October 2015

Atom-centered point charge (PC) model of the molecular electrostatics—a major workhorse of the atomistic biomolecular simulations—is usually parameterized by least-squares (LS) fitting of the point charge values to a reference electrostatic potential, a procedure that suffers from numerical instabilities due to the ill-conditioned nature of the LS problem. To reveal the origins of this ill-conditioning, we start with a general treatment of the point charge fitting problem as an inverse problem and construct an analytical model with the point charges spherically arranged according to Lebedev quadrature which is naturally suited for the inverse electrostatic problem. This analytical model is contrasted to the atom-centered point-charge model that can be viewed as an irregular quadrature poorly suited for the problem. This analysis shows that the numerical problems of the point charge fitting are due to the decay of the curvatures corresponding to the eigenvectors of LS sum Hessian matrix. In part, this ill-conditioning is intrinsic to the problem and is related to decreasing electrostatic contribution of the higher multipole moments, that are, in the case of Lebedev grid model, directly associated with the Hessian eigenvectors. For the atom-centered model, this association breaks down beyond the first few eigenvectors related to the high-curvature monopole and dipole terms; this leads to even wider spread-out of the Hessian curvature values. Using these insights, it is possible to alleviate the ill-conditioning of the LS point-charge fitting without introducing external restraints and/or constraints. Also, as the analytical Lebedev grid PC model proposed here can reproduce multipole moments up to a given rank, it may provide a promising alternative to including explicit multipole terms in a force field.
Monolithically integrated organic resistive switches for luminance and emission color manipulation in polymer light emitting diodes
Authors: Nau Sebastian , Sørdal Vegard B. , Wolf Christoph , Sax Stefan , List-Kratochvil Emil J. W.
Published: October 2015

The rising significance of organic light emitting diodes as lighting devices puts their peripheral devices into focus as well. Here, we present an organic optoelectronic device allowing for multistable luminance and emission color control. The introduced device is monolithically built up from organic resistive switching elements processed directly on top of a polymer light emitting diode (PLED). This realization, representing a serial connection, allows for precise control of the voltage drop across and thus the current density through the PLED resulting in a control of its luminance. Additionally, by using a fluorescence-phosphoresence host-guest blend as the light emitting layer, it is possible to tune the emission color in the same way. Specifically, focus was set on color temperature tuning in a white light emitting diode. Notable, for all different luminance and color states, the driving voltage is constant, enabling, e.g., a conventional battery as power supply.
Photon upconversion with hot carriers in plasmonic systems
Authors: Naik Gururaj V. , Dionne Jennifer A.
Published: October 2015

We propose a scheme of photon upconversion based on harnessing the energy of plasmonic hot carriers. Low-energy photons excite hot electrons and hot holes in a plasmonic nanoparticle, which are then injected into an adjacent semiconductor quantum well where they radiatively recombine to emit a photon of higher energy. We theoretically study the proposed upconversion scheme using Fermi-liquid theory and determine the internal quantum efficiency of upconversion to be as high as 25% in 5 nm silver nanocubes. This upconversion scheme is linear in its operation, does not require coherent illumination, offers spectral tunability, and is more efficient than conventional upconverters.
Bimodal magnetic force microscopy with capacitive tip-sample distance control
Authors: Schwenk J. , Zhao X. , Bacani M. , Marioni M. A. , Romer S. , Hug H. J.
Published: October 2015

A single-passage, bimodal magnetic force microscopy technique optimized for scanning samples with arbitrary topography is discussed. A double phase-locked loop system is used to mechanically excite a high quality factor cantilever under vacuum conditions on its first mode and via an oscillatory tip-sample potential on its second mode. The obtained second mode oscillation amplitude is then used as a proxy for the tip-sample distance, and for the control thereof. With appropriate z-feedback parameters, two data sets reflecting the magnetic tip-sample interaction and the sample topography are simultaneously obtained.
Dynamics of copper-phthalocyanine molecules on Au/Ge(001)
Authors: Sotthewes K. , Heimbuch R. , Zandvliet H. J. W.
Published: October 2015

Spatially resolved current-time scanning tunneling spectroscopy combined with current-distance spectroscopy has been used to characterize the dynamic behavior of copper-phthalocyanine (CuPc) molecules adsorbed on a Au-modified Ge(001) surface. The analyzed CuPc molecules are adsorbed in a “molecular bridge” configuration, where two benzopyrrole groups (lobes) are connected to a Au-induced nanowire, whereas the other two lobes are connected to the adjacent nanowire. Three types of lobe configurations are found: a bright lobe, a dim lobe, and a fuzzy lobe. The dim and fuzzy lobes exhibit a well-defined switching behavior between two discrete levels, while the bright lobe shows a broad oscillation band. The observed dynamic behavior is induced by electrons that are injected into the LUMO+1 orbital of the CuPc molecule. By precisely adjusting the tip-molecule distance, the switching frequency of the lobes can be tuned accurately.
Communication: Broadband and ultrasensitive femtosecond time-resolved circular dichroism spectroscopy
Authors: Hiramatsu Kotaro , Nagata Takashi
Published: October 2015

We report the development of broadband and sensitive time-resolved circular dichroism (TRCD) spectroscopy by exploiting optical heterodyne detection. Using this method, transient CD signals of submillidegree level can be detected over the spectral range of 415-730 nm. We also demonstrate that the broadband measurement with the aid of singular value decomposition enables the discrimination of genuine TRCD signals from artificial optical-anisotropy, such as linear birefringence and linear dichroism, induced by photoexcitation.
Keeping fusion plasmas hot
Authors: Pace David C. , Heidbrink William W. , Van Zeeland Michael A.
Published: October 2015

Interactions between electromagnetic waves and the most energetic ions in a plasma can perturb the orbits of those ions enough to expel them from the confining magnetic field.
An early history of high-intensity focused ultrasound
Authors: O’Brien William D. , Dunn Floyd
Published: October 2015

Foresighted leadership, the GI Bill, and research conducted in an unventilated steam tunnel all contributed to the development of a now ubiquitous medical tool.
How does grinding affect the mid-infrared spectra of soil and their multivariate calibrations to texture and organic carbon?
Authors: Guillou F. Le , Wetterlind W. , Viscarra Rossel R. A. , Hicks W. , Grundy M. , Tuomi S.
Published: October 2015

Mid-infrared (mid-IR) diffuse reflectance spectroscopy can be used to effectively analyse soil, but the preparation of soil samples by grinding is time consuming. Soil samples are usually finely ground to a particle size of less than 0.250 mm because the spectrometer’s beam aperture is approximately 1–2 mm in diameter. Larger particles can generate specular reflections and spectra that do not adequately represent the soil sample. Grinding soil to small particle sizes enables the diffuse reflectance of light and more representative sample measurements. Here, we report on research that investigates the effect that grinding to different particle sizes have on soil mid-IR spectra. Our aims were to compare the effect of grinding soil to different particle sizes (2.000 mm, 1.000 mm, 0.500 mm, 0.250 mm and 0.106 mm) on the frequencies of mid-IR spectra, and compare the effect of these particle sizes on the accuracy of spectroscopic calibrations to predict organic carbon, sand, silt and clay contents. Using the Commonwealth Scientific and Industrial Research Organisation’s (CSIRO) National visible–near infrared database, we selected 227 soil samples from the National Soil Archive for our experiments, and designed an experiment whereby each soil sample was ground in triplicate to the different particle sizes. These ground samples were measured using an FT-IR spectrometer with a spectral range of 4000–600 cm–1. Grinding to particle sizes that are ≤2.000 mm reduces subsample variability. Smaller particle sizes produce finer and sharper absorption features, which are related to organic carbon, and clay and sand mineralogies. Generally, better predictions for clay, sand and soil organic carbon contents were achieved using soil that is more finely ground, but there were no statistically significant differences between predictions that use soil ground to 1 mm, 0.5 mm, 0.25 mm. Grinding did not affect predictions of silt content. Recommendations on how much grinding is required for mid-IR analysis should also consider the time, cost and effort needed to prepare the soil samples as well as the purpose of the analysis.
The organisation of kinesic ensembles associated with negation
Authors: Harrison Simon
Published: October 2015

This paper describes the organisation of kinesic ensembles associated with negation in speech through a qualitative study of negative utterances identified in face-to-face conversations between English speakers. All the utterances contain a verbal negative particle (no,not,nothing, etc.) and the kinesic ensembles comprise Open Hand Prone gestures and head shakes, both associated with the expression of negation in previous studies (e.g., Kendon, 2002, 2004; Calbris, 1990, 2011; Harrison, 2009, 2010). To analyse how these elements relate to each other, the utterances were studied in ELAN annotation software with separate analytical tiers for aspects of form in both speech and gestures. The micro-analysis of the temporal and semantic coordination between tiers shows that kinesic ensembles are organized in relation to the node, scope, and focus of negation in speech. Speakers coordinate gesture phrase structures of both head and hand gestures in relation to the grammar of verbal negation, and the gestures they use share a core formational feature that expresses a negative semantic theme in line with the expression of negation in the verbal utterance. The paper demonstrates these connections between grammar and gesture and sheds light on the mechanics of ‘multimodal negation’ at the utterance level.
Asymptotic behavior of densities of unimodal convolution semigroups
Authors: Cygan Wojciech , Grzywny Tomasz , Trojan Bartosz
Published: October 2015

We prove the asymptotic formulas for the densities of isotropic unimodal convolution semigroups of probability measures on

R

d

\mathbb {R}^d

under the assumption that its Lévy–Khintchine exponent is regularly varying of index between

0
0

and

2
2

.
The Intersecting Epidemics of Human Immunodeficiency Virus, Community-Associated Methicillin-Resistant Staphylococcus aureus, and Incarceration
Authors: Popovich Kyle J. , Zawitz Chad , Weinstein Robert A. , Grasso Amanda E. , Hotton Anna L. , Hota Bala
Published: October 2015

Community-associated methicillin-resistant Staphylococcus aureus (MRSA) has had a significant impact on human immunodeficiency virus (HIV)-infected and incarcerated individuals. We examined electronic medical surveillance data from 2006 to 2011 and observed that even in a population of currently or recently incarcerated individuals, HIV status was a significant risk factor for MRSA infections and Hispanic ethnicity was protective.
JVLA S- and X-band polarimetry of the merging cluster Abell 2256
Authors: Ozawa Takeaki , Nakanishi Hiroyuki , Akahori Takuya , Anraku Kenta , Takizawa Motokazu , Takahashi Ikumi , Onodera Sachiko , Tsuda Yuya , Sofue Yoshiaki
Published: October 2015

We report on polarimetry results of a merging cluster of galaxies, Abell 2256, with the Karl G. Jansky Very Large Array (JVLA). We performed new observations with JVLA at the S band (2051–3947 MHz) and X band (8051–9947 MHz) in the C array configuration, and detected significant polarized emissions from the radio relic, Source A, and Source B in this cluster. We calculated the total magnetic-field strengths toward the radio relic using revised equipartition formula, which is 1.8–5.0 μG. With dispersions of Faraday rotation measure, the magnetic-field strengths toward Sources A and B are estimated to be 0.63–1.26 μG and 0.11–0.21 μG, respectively. An extremely high degree of linear polarization, as high as ∼ 35%, about a half of the maximum polarization, was detected toward the radio relic, which indicates highly ordered magnetic lines of force over the beam sizes (∼ 52 kpc). The fractional polarization of the radio relic decreases from ∼ 35% to ∼ 20% at around 3 GHz as the frequency decreases, and is nearly constant between 1.37 and 3 GHz. Both analyses with depolarization models and Faraday tomography suggest multiple depolarization components toward the radio relic and imply the existence of turbulent magnetic fields.
Use of broad-spectrum antibiotics in French EDs: different trends for third-generation cephalosporins and fluoroquinolones
Authors: Batard Eric , Vibet Marie-Anne , Lemarchand Cathelle , Navas Dominique , Lepelletier Didier , Potel Gilles , Montassier Emmanuel
Published: October 2015

Objectives

Third-generation cephalosporins and fluoroquinolones are particularly prone to promoting bacterial resistance. Their use in Emergency Departments (EDs) is poorly known. Our objectives were to assess the use of antibacterial agents in French EDs.

Methods

This study is a retrospective study of antibiotics delivered to the adult units of 11 EDs of French academic centres in 2012, and to six of these EDs between 2009 and 2012.

Results

The total antibiotic use was 66.4 defined daily doses (DDD)/1000 ED visits in 2012, and it increased between 2009 and 2012 (yearly estimate, +1.8±0.9 DDD/1000 ED visits, P=0.048). The 3GC-FQ class, which grouped third-generation cephalosporins and fluoroquinolones, accounted for 39.2% of the total antibiotic use, and the use of this class of antibiotics was highly variable among EDs (range, 31.6–49.5% of total antibiotic use). The aminopenicillin and β-lactamase inhibitor/3GC-FQ ratio varied among EDs [median (range), 0.91 (0.52–1.25)]. Between 2009 and 2012, there was a significant decrease in the use of the 3GC-FQ class (yearly estimate, −0.8±0.4% of total antibiotic use), antipneumococcal fluoroquinolones (−0.8±0.3%) and other fluoroquinolones (−0.9%±0.3%), and there was a significant increase in the use of third-generation cephalosporins (+0.7±0.3%), aminoglycosides (+0.4±0.1%), imidazole derivatives (+0.4±0.1%) and lincosamides (+0.1±0.0%).

Conclusion

Fluoroquinolones and third-generation cephalosporins are widely used in the ED. Their use is highly variable among EDs. Third-generation cephalosporins were increasingly used between 2009 and 2012, whereas the use of fluoroquinolones decreased. Reduced use of cephalosporins in the ED, without increasing fluoroquinolone use, should be aimed at through antibiotic stewardship programs.
Modular Combinatorial Binding among HumanTrans-acting Factors Reveals Direct and Indirect Factor Binding
Authors: Guo Yuchun , Gifford David K.
Published: October 2015

The combinatorial binding oftrans-acting factors (TFs) to regulatory genomic regions is an important basis for the spatial and temporal specificity of gene regulation. We present a new computational approach that reveals how TFs are organized into combinatorial regulatory programs. We define a regulatory program to be a set of TFs that bind together at a regulatory region. Unlike other approaches to characterizing TF binding, we permit a regulatory region to be bound by one or more regulatory programs. We have developed a method called regulatory program discovery (RPD) that produces compact and coherent regulatory programs fromin vivobinding data using a topic model. Using RPD we find that the binding of 115 TFs in K562 cells can be organized into 49 interpretable regulatory programs that bind ~140,000 distinct regulatory regions in a modular manner. The discovered regulatory programs recapitulate many published protein-protein physical interactions and have consistent functional annotations of chromatin states. We found that, for certain TFs, direct (motif present) and indirect (motif absent) binding is characterized by distinct sets of binding partners and that the binding of other TFs can predict whether the TF binds directly or indirectly with high accuracy. Joint analysis across two cell types reveals both cell-type-specific and shared regulatory programs and that thousands of regulatory regions use different programs in different cell types. Overall, our results provide comprehensive cell-type-specific combinatorial binding maps and suggest a modular organization of binding programs in regulatory regions.
Signatures of post-zygotic structural genetic aberrations in the cells of histologically normal breast tissue that can predispose to sporadic breast cancer
Authors: Forsberg Lars A. , Rasi Chiara , Pekar Gyula , Davies Hanna , Piotrowski Arkadiusz , Absher Devin , Razzaghian Hamid Reza , Ambicka Aleksandra , Halaszka Krzysztof , Przewoźnik Marcin , Kruczak Anna , Mandava Geeta , Pasupulati Saichand , Hacker Julia , Prakash K. Reddy , Dasari Ravi Chandra , Lau Joey , Penagos-Tafurt Nelly , Olofsson Helena M. , Hallberg Gunilla , Skotnicki Piotr , Mituś Jerzy , Skokowski Jaroslaw , Jankowski Michal , Śrutek Ewa , Zegarski Wojciech , Tiensuu Janson Eva , Ryś Janusz , Tot Tibor , Dumanski Jan P.
Published: October 2015

Sporadic breast cancer (SBC) is a common disease without robust means of early risk prediction in the population. We studied 282 females with SBC, focusing on copy number aberrations in cancer-free breast tissue (uninvolved margin, UM) outside the primary tumor (PT). In total, 1162 UMs (1–14 per breast) were studied. Comparative analysis between UM(s), PT(s), and blood/skin from the same patient as a control is the core of the study design. We identified 108 patients with at least one aberrant UM, representing 38.3% of cases. Gains in gene copy number were the principal type of mutations in microscopically normal breast cells, suggesting that oncogenic activation of genes via increased gene copy number is a predominant mechanism for initiation of SBC pathogenesis. The gain of ERBB2, with overexpression of HER2 protein, was the most common aberration in normal cells. Five additional growth factor receptor genes (EGFR, FGFR1, IGF1R, LIFR, and NGFR) also showed recurrent gains, and these were occasionally present in combination with the gain of ERBB2. All the aberrations found in the normal breast cells were previously described in cancer literature, suggesting their causative, driving role in pathogenesis of SBC. We demonstrate that analysis of normal cells from cancer patients leads to identification of signatures that may increase risk of SBC and our results could influence the choice of surgical intervention to remove all predisposing cells. Early detection of copy number gains suggesting a predisposition toward cancer development, long before detectable tumors are formed, is a key to the anticipated shift into a preventive paradigm of personalized medicine for breast cancer.
Genomic approaches for understanding the genetics of complex disease
Authors: Lowe William L. , Reddy Timothy E.
Published: October 2015

There are thousands of known associations between genetic variants and complex human phenotypes, and the rate of novel discoveries is rapidly increasing. Translating those associations into knowledge of disease mechanisms remains a fundamental challenge because the associated variants are overwhelmingly in noncoding regions of the genome where we have few guiding principles to predict their function. Intersecting the compendium of identified genetic associations with maps of regulatory activity across the human genome has revealed that phenotype-associated variants are highly enriched in candidate regulatory elements. Allele-specific analyses of gene regulation can further prioritize variants that likely have a functional effect on disease mechanisms; and emerging high-throughput assays to quantify the activity of candidate regulatory elements are a promising next step in that direction. Together, these technologies have created the ability to systematically and empirically test hypotheses about the function of noncoding variants and haplotypes at the scale needed for comprehensive and systematic follow-up of genetic association studies. Major coordinated efforts to quantify regulatory mechanisms across genetically diverse populations in increasingly realistic cell models would be highly beneficial to realize that potential.