WorldWideScience

Sample records for nonmagnetic impurity hopping

  1. The Potts model on a Bethe lattice with nonmagnetic impurities

    Energy Technology Data Exchange (ETDEWEB)

    Semkin, S. V., E-mail: li15@rambler.ru; Smagin, V. P. [Vladivistok State University of Economics and Service (VSUES) (Russian Federation)

    2015-10-15

    We have obtained a solution for the Potts model on a Bethe lattice with mobile nonmagnetic impurities. A method is proposed for constructing a “pseudochaotic” impurity distribution by a vanishing correlation in the arrangement of impurity atoms for the nearest sites. For a pseudochaotic impurity distribution, we obtained the phase-transition temperature, magnetization, and spontaneous magnetization jumps at the phase-transition temperature.

  2. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors.

    Science.gov (United States)

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V

    2015-07-03

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm(2) cross-section. The impurities suppress superconductivity in a three-dimensional 'Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

  3. Non-magnetic impurity effects in LiFeAs studied by STM/STS

    Science.gov (United States)

    Hanaguri, T.; Khim, Seung Hyun; Lee, Bumsung; Kim, Kee Hoon; Kitagawa, K.; Matsubayashi, K.; Mazaki, Y.; Uwatoko, Y.; Takigawa, M.; Takagi, H.

    2012-02-01

    Detecting the possible sign reversal of the superconducting gap in iron-based superconductors is highly non-trivial. Here we use non-magnetic impurity as a sign indicator. If the sign of the superconducting gap is positive everywhere in momentum space, in-gap bound state should not be observed near the impurity site unless it is magnetic. On the other hand, if there is a sign-reversal in the gap, even non-magnetic impurity may create in-gap bound state [1]. We performed STM/STS experiments on self-flux and Sn-flux grown LiFeAs crystals and examined the effects of Sn impurity. In STM images of Sn-flux grown samples, we found a ring-like object which may represent Sn. Tunneling spectrum taken at this defect site exhibits in-gap bound state. Together with flat-bottom superconducting gap observed far from the defects, sign-reversing s-wave gap is the most plausible gap structure in LiFeAs. [1] T. Kariyado and M. Ogata, JPSJ 79, 083704 (2010).

  4. Novel magnetic half-metallic materials based on ionic insulators doped with nonmagnetic impurities: MgO + B, C, N Systems

    Science.gov (United States)

    Bannikov, V. V.; Shein, I. R.; Ivanovskii, A. L.

    2007-07-01

    It is established that magnesium oxide (a nonmagnetic ionic insulator) exhibits a transition to the state of a magnetic half-metal upon the introduction of nonmagnetic impurities (boron, carbon, or nitrogen) into the crystal lattice. The possibility of obtaining novel magnetic materials for spintronics by doping ionic insulators with nonmagnetic impurities is discussed.

  5. The Effect of Nonmagnetic Impurities on Phase-Transition Kinetics and Correlation Effects in a Quasi-1D Ising Nanomagnetic

    Science.gov (United States)

    Shabunina, E. V.; Spirin, D. V.; Popov, A. A.; Udodov, V. N.; Potekaev, A. I.

    2013-05-01

    Using a Monte Carlo simulation, the effect of external field, temperature, system's dimensions and interaction of non-nearest neighbors on the relaxation time and critical indices of an antiferromagnetic-to-ferromagnetic phase transition is investigated taking into account nonmagnetic impurities within a modified, onedimensional, nanosized Ising model. It is shown that the non-equilibrium processes taking place in the magnetic material could be classified as fast and slow, whose velocities differ by more than a thousand times. In the case of fast processes, metastable (including ferromagnetic) states (observed experimentally) are the first to form, while in the case of slow processes the system transits into a stable state. The behavior of the dynamic critical exponent ( z) and static correlation-length critical exponent ( ν) is revealed for the model of a 1D ferromagnetic for the case of arbitrary concentrations of nonmagnetic impurities.

  6. Tricritical wetting in the two-dimensional Ising magnet due to the presence of localized non-magnetic impurities.

    Science.gov (United States)

    Trobo, Marta L; Albano, Ezequiel V

    2016-03-31

    Fixed vacancies (non-magnetic impurities) are placed along the centre of Ising strips in order to study the wetting behaviour in this confined system, by means of numerical simulations analysed with the aid of finite size scaling and thermodynamic integration methods. By considering strips of size L × M (L interface between magnetic domains of different orientation (driven by the corresponding surface fields), which are the precursors of the wetting transitions that occur in the thermodynamic limit. By placing vacancies or equivalently non-magnetic impurities along the centre of the sample, we found that for low vacancy densities the wetting transitions are of second order, while by increasing the concentration of vacancies the transitions become of first order. Second- and first-order lines meet in tricritical wetting points (H(tric)(SW), T(tric)(W)), where H(tric)(SW) and T(Tric)(W) are the magnitude of the surface field and the temperature, respectively. In the phase diagram, tricritical points shift from the high temperature and weak surface field regime at large vacancy densities to the T --> 0, H(tric)(SW) --> 1 limit for low vacancy densities. By comparing the locations of the tricritical points with those corresponding to the case of mobile impurities, we conclude that in order to observe similar effects, in the latter the required density of impurities is much smaller (e.g. by a factor 3-5). Furthermore, a proper density of non magnetic impurities placed along the centre of a strip can effectively pin rather flat magnetic interfaces for suitable values of the competing surface fields and temperature.

  7. Nonmagnetic impurity resonances as a signature of sign-reversal pairing in FeAs-based superconductors.

    Science.gov (United States)

    Zhang, Degang

    2009-10-30

    The energy band structure of FeAs-based superconductors is fitted by a tight-binding model with two Fe ions per unit cell and two degenerate orbitals per Fe ion. Based on this, superconductivity with extended s-wave pairing symmetry of the form cosk(x)+cosk(y) is examined. The local density of states near an impurity is also investigated by using the T-matrix approach. For the nonmagnetic scattering potential, we found that there exist two major resonances inside the gap. The height of the resonance peaks depends on the strength of the impurity potential. These in-gap resonances are originated in the Andreev's bound states due to the quasiparticle scattering between the hole Fermi surfaces around Gamma point with positive order parameter and the electron Fermi surfaces around M point with negative order parameter.

  8. Simulation and measurement of ferromagnetic impurities in non-magnetic aeroengine turbine disks using fluxgate magnetometers

    Directory of Open Access Journals (Sweden)

    Sebastian Hantscher

    2015-11-01

    Full Text Available In this paper, ferromagnetic impurities in paramagnetic aeroengine turbine disks are investigated. Because such inclusions represent a significant threat in aviation, a detailed analysis is required for impured turbine disks. For this purpose, sensitive fluxgate magnetometers are used. After a premagnetisation, this sensor is able to detect small ferromagnetic particles by recording the variation of the magnetic flux density while the disk rotates below the sensor head. This trajectory creates a unique signature. However, the measured signatures are often distorted. A main reason for these distortions is that the particles are not oriented in axial direction (in the direction of the disks axis. Up to now, it was not possible to interpret the measured signatures. Thus, a simulation tool has been developed that provides a catalogue of different magnetic flux density distributions of typical orientations, positions and various distances to the fluxgate magnetometer position. For these simulations, the particles are assumed to be dipoles. As part of impurities are not caused by concentrated particles but by elongated ones, so-called or dipole lines, the model has been expanded for these cases by using numerical integration techniques. Measurements verify the assumption to approximate impurities by dipoles.

  9. Magnetic properties and the effect of non-magnetic impurities in the quasi-2D quantum magnet

    Science.gov (United States)

    Khuntia, P.; Dey, T.; Mahajan, A. V.

    2016-09-01

    We present synthesis, x-ray diffraction, magnetisation and specific heat studies on the quasi-two-dimensional (2D) S = 1/2 antiferromagnet (CuCl)LaNb2O7 and its doping analogues (Cu1-x Zn x Cl)LaNb2O7 (0 ≤ x ≤ 0.05), (Cu0.95Mg0.05Cl)LaNb2O7, and (CuCl)La1-y Ba y Nb2O7 (0 ≤ y ≤ 0.10). The magnetic susceptibility and specific heat of the parent compound and its isovalent or hetereovalent counterparts do not display any signature of magnetic ordering down to 1.8 K. The parent compound and its doping variants exhibit spin-singlet behaviour with a finite gap in the spin excitation spectrum due to dimerisation of the dominant intradimer interactions as evidenced from our magnetic susceptibility and specific heat data. The systematic increase of magnetic susceptibility at low temperature with non-magnetic Zn2+ and Mg2+ (S = 0) substitution at the Cu2+ site reflect that impurities induce local moments around the non-magnetic sites. While heterovalent Ba2+ substitution at the La3+ site do not result in mobile holes but rather give rise to a Curie term in the susceptibility due to localisation. The low value of spin S = 1/2, and absence of long range ordering or spin freezing, and the presence of competing exchange interactions hold special significance in hosting novel magnetic properties in this class of quasi-2D quantum material.

  10. Exchange Bias Tuning for Magnetoresistive Sensors by Inclusion of Non-Magnetic Impurities.

    Science.gov (United States)

    Sharma, Parikshit Pratim; Albisetti, Edoardo; Monticelli, Marco; Bertacco, Riccardo; Petti, Daniela

    2016-07-04

    The fine control of the exchange coupling strength and blocking temperature ofexchange bias systems is an important requirement for the development of magnetoresistive sensors with two pinned electrodes. In this paper, we successfully tune these parameters in top- and bottom-pinned systems, comprising 5 nm thick Co40Fe40B20 and 6.5 nm thick Ir22Mn78 films. By inserting Ru impurities at different concentrations in the Ir22Mn78 layer, blocking temperatures ranging from 220 °C to 100 °C and exchange bias fields from 200 Oe to 60 Oe are obtained. This method is then applied to the fabrication of sensors based on magnetic tunneling junctions consisting of a pinned synthetic antiferromagnet reference layer and a top-pinned sensing layer. This work paves the way towards the development of new sensors with finely tuned magnetic anisotropies.

  11. Exchange Bias Tuning for Magnetoresistive Sensors by Inclusion of Non-Magnetic Impurities

    Directory of Open Access Journals (Sweden)

    Parikshit Pratim Sharma

    2016-07-01

    Full Text Available The fine control of the exchange coupling strength and blocking temperature ofexchange bias systems is an important requirement for the development of magnetoresistive sensors with two pinned electrodes. In this paper, we successfully tune these parameters in top- and bottom-pinned systems, comprising 5 nm thick Co40Fe40B20 and 6.5 nm thick Ir22Mn78 films. By inserting Ru impurities at different concentrations in the Ir22Mn78 layer, blocking temperatures ranging from 220 °C to 100 °C and exchange bias fields from 200 Oe to 60 Oe are obtained. This method is then applied to the fabrication of sensors based on magnetic tunneling junctions consisting of a pinned synthetic antiferromagnet reference layer and a top-pinned sensing layer. This work paves the way towards the development of new sensors with finely tuned magnetic anisotropies.

  12. Effect of Single Particle Hopping and Out of Plane Magnetic Impurity on Coupled Planar Superconductors

    Science.gov (United States)

    Sardar, Manas; Sa, Debanand

    It is shown that the single particle band motion along the c axis is harmful for superconductivity in anisotropic systems. Variation of Tc with c axis hopping parameter is shown for both the conventional Josephson coupled, planar superconductors and for interlayer pair tunneling mechanism of Wheatley, Hsu, and Anderson (WHA). Effect of out-of-plane magnetic impurity substitution is shown to suppress Tc more for conventional superconductors whereas there is a very sharp decrease of Tc in the WHA mechanism at larger concentrations.

  13. Effect of single particle hopping and out of plane magnetic impurity on coupled planar superconductors

    CERN Document Server

    Sardar, M; Manas Sardar; Debanand Sa

    1994-01-01

    It is shown that the single particle band motion along the c axis is harmful for superconductivity. Variation of T_c with c axis hopping parameter is shown for both the conventional planar superconductors and for interlayer pair tunneling mechanism of Wheatley Hsu and Anderson(WHA).Effect of out of plane magnetic impurity substitution is shown to suppres T_c more for conventional superconductors whereas there is very sharp decrease of T_c in the WHA mechanism at larger concentrations.

  14. Investigation of the influence of quenched nonmagnetic impurities on phase transitions in the three-dimensional Potts model

    Science.gov (United States)

    Murtazaev, A. K.; Babaev, A. B.; Aznaurova, G. Ya.

    2008-04-01

    The influence of quenched nonmagnetic impurities on phase transitions in the three-dimensional Potts model with the number of spin states q = 3 is investigated using the Wolff single-cluster algorithm of the Monte Carlo method. The systems with linear sizes L = 20-44 at the spin concentrations p = 1.0, 0.9, 0.8, and 0.7 are analyzed. It is demonstrated with the use of the method of fourth-order Binder cumulants that the second-order phase transition occurs in the model under consideration at the spin concentrations p = 0.9, 0.8, and 0.7 and that the first-order phase transition is observed in the pure model ( p = 1.0). The static critical exponents α (heat capacity), γ (susceptibility), β (magnetization), and ν (correlation length) are calculated in the framework of the finite-size scaling theory. The problem regarding the universality classes of the critical behavior of weakly diluted systems is discussed.

  15. Effect of nonmagnetic zinc impurity on Tc in LaFe1−xZnxPO0.94F0.06 superconductors

    Directory of Open Access Journals (Sweden)

    Yuke Li

    2012-12-01

    Full Text Available We study the effect of nonmagnetic Zn impurity on superconductivity in the LaFe1−yZnyPO0.94F0.06 system by measuring the transport and magnetic properties. It is found that Zn doping drastically suppresses the superconducting transition temperature Tc. This is consistent with the theoretic prediction in the scenario of s±-wave or d-wave pairing.

  16. First- and second-order wetting transitions in confined Ising films in the presence of nonmagnetic impurities: A Monte Carlo simulation study

    Science.gov (United States)

    Cotes, S. M.; Albano, E. V.

    2011-06-01

    In this work, we present the results of a systematic exploration of the effect caused by the introduction of nonmagnetic impurities (or defects) on the stabilization of the interface between two magnetic domains of opposite magnetic orientation. Those defects are simulated as spin vacancies along the center of confined two-dimensional Ising films, which have competing magnetic fields acting on the confinement walls. The calculations are performed for different L×M film sizes and by using the standard Metropolis dynamics. In the absence of defects, the film is characterized by an interface running along the M direction, which is induced by the competing surface fields. That interface undergoes a localization-delocalization transition that is the precursor of a true wetting transition taking place in the thermodynamic limit. When the density of defects is relatively low, our results show that the wetting phase transition is of second order, as in the absence of defects. On the other hand, when the density of nonmagnetic impurities is relatively high, a pinning effect of the interface gives rise to a first-order wetting phase transition. The observed transitions are characterized by measuring relevant properties, such as magnetization profiles, cumulants, magnetization fluctuations, etc., as a function of the density of defects. So, our main finding is that the presence of nonmagnetic impurities introduces a rich physical scenery, such as a line of second-order wetting transitions (observed for low density of defects) that merges into a first-order one just at a tricritical point. Precisely, these two latter findings are the major contributions of our study.

  17. First- and second-order wetting transitions in confined Ising films in the presence of nonmagnetic impurities: a Monte Carlo simulation study.

    Science.gov (United States)

    Cotes, S M; Albano, E V

    2011-06-01

    In this work, we present the results of a systematic exploration of the effect caused by the introduction of nonmagnetic impurities (or defects) on the stabilization of the interface between two magnetic domains of opposite magnetic orientation. Those defects are simulated as spin vacancies along the center of confined two-dimensional Ising films, which have competing magnetic fields acting on the confinement walls. The calculations are performed for different L×M film sizes and by using the standard Metropolis dynamics. In the absence of defects, the film is characterized by an interface running along the M direction, which is induced by the competing surface fields. That interface undergoes a localization-delocalization transition that is the precursor of a true wetting transition taking place in the thermodynamic limit. When the density of defects is relatively low, our results show that the wetting phase transition is of second order, as in the absence of defects. On the other hand, when the density of nonmagnetic impurities is relatively high, a pinning effect of the interface gives rise to a first-order wetting phase transition. The observed transitions are characterized by measuring relevant properties, such as magnetization profiles, cumulants, magnetization fluctuations, etc., as a function of the density of defects. So, our main finding is that the presence of nonmagnetic impurities introduces a rich physical scenery, such as a line of second-order wetting transitions (observed for low density of defects) that merges into a first-order one just at a tricritical point. Precisely, these two latter findings are the major contributions of our study.

  18. Hops

    Science.gov (United States)

    ... the skin for leg ulcers and as an antibacterial agent. In foods and beverages, the extracts and ... that applying 1-2 grams of a vaginal gel that contains hops, hyaluronic acid, liposomes, and vitamin ...

  19. Hopping conduction via highly localized impurity states of indium in PbTe and its solid solutions. Review

    CERN Document Server

    Ravich, Y I

    2002-01-01

    Results of experimental investigation of the transport phenomena in PbTe and Pb sub 1 sub - sub x Sn sub x Te solid solutions with high contents of In impurity (up to 20 at %) at temperatures up to 400 K have been considered. An analysis of the experimental data has been made on the base of an idea of hopping conductivity via highly localized impurity states creates by indium atoms. The temperature dependences of transport coefficients unusual for the IV-VI-type semiconductors, the change of sing of the thermoelectromotive force at negative Hall coefficient, the positive Nernst-Ettingshausen coefficient are explained. The activation energy of the hoping conductivity, characterizing discrepancy between impurity energy levels the effective wave function radius and the density of localized states as the energy function are found experimentally

  20. CuO2平面外非磁性杂质对gossamer超导体局域态密度的影响%Effect of Nonmagnetic Impurity out of CuO2 Plane on Local Density of States in Gossamer Superconductors

    Institute of Scientific and Technical Information of China (English)

    万霞霞; 任玉英; 袁峰

    2012-01-01

    Using the Gutzwiller approximation and Bogoliubov-de Gennes (BdG) theory, the local density of states around the nonmagnetic impurity out of the C11O2 plane in gossamer superconductors is studied within the t-J -U model. Results show that the LDOS shows typical "V" shape asmmetric curve away from the impurities. The superconducting gap reduces around the impurity, but the impurity does not destroy the superconducting. We find that the inhomogeneity originates from nonlinear screening of the ionic potential which was introduced by the doped nonmagnetic impurity.%在t-J-U模型下,应用Gutzwiller平均场近似及Bogoliubov-de Gennes(BdG)理论研究了CuO2平面外单个非磁性杂质对gossamer超导体电子局域态密度的影响.结果表明,在远离杂质点处电子局域态密度呈现出典型的非对称性,在杂质点附近平面外的非磁性杂质使超导能隙变小,但是并没有明显破坏超导.而在杂质点附近由于平面外的杂质势没有被有效屏蔽而导致CuO2平面内电子的分布在纳米尺度上存在着明显的不均匀性.

  1. Minimizing the scattering of a nonmagnetic cloak

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Luo, Yu; Mortensen, Asger

    2010-01-01

    Nonmagnetic cloak offers a feasible way to achieve invisibility at optical frequencies using materials with only electric responses. In this letter, we suggest an approximation of the ideal nonmagnetic cloak and quantitatively study its electromagnetic characteristics using a full-wave scattering...

  2. Rigorous analysis of non-magnetic cloaks

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Luo, Yu; Mortensen, Asger

    2010-01-01

    Nonmagnetic cloak offers a feasible way to achieve invisibility at optical frequencies using materials with only electric responses. In this letter, we suggest an approximation of the ideal nonmagnetic cloak and quantitatively study its electromagnetic characteristics using a full-wave scattering...

  3. Zeroth Order Phase Transition in a Holographic Superconductor with Single Impurity

    CERN Document Server

    Zeng, Hua Bi

    2014-01-01

    We studied the single normal impurity effect in superconductor by using the holographic method. When the size of impurity is much smaller compared to the host superconductor, we reproduced the Anderson theorem, which states that a conventional s-wave superconductor is robust to a normal (non-magnetic) impurity with small impurity strength or impurities with small concentration. While by increasing the size of impurity in a fixed host superconductor we also find a decrease $T_c$ of the host superconductor, the phase transition at the critical impurity strength is of zeroth order.

  4. Susceptibility of the 2D spin-1 / 2 Heisenberg antiferromagnet with an impurity.

    Science.gov (United States)

    Höglund, Kaj H; Sandvik, Anders W

    2003-08-15

    We use a quantum Monte Carlo method (stochastic series expansion) to study the effects of a magnetic or nonmagnetic impurity on the magnetic susceptibility of the two-dimensional Heisenberg antiferromagnet. At low temperatures, we find a log-divergent contribution to the transverse susceptibility. We also introduce an effective few-spin model that can quantitatively capture the differences between magnetic and nonmagnetic impurities at high and intermediate temperatures.

  5. Magnetic-Field-Modulated Resonant Tunneling in Ferromagnetic-Insulator-Nonmagnetic Junctions

    Science.gov (United States)

    Song, Yang; Dery, Hanan

    2014-07-01

    We present a theory for resonance-tunneling magnetoresistance (MR) in ferromagnetic-insulator-nonmagnetic junctions. The theory sheds light on many of the recent electrical spin injection experiments, suggesting that this MR effect rather than spin accumulation in the nonmagnetic channel corresponds to the electrically detected signal. We quantify the dependence of the tunnel current on the magnetic field by quantum rate equations derived from the Anderson impurity model, with the important addition of impurity spin interactions. Considering the on-site Coulomb correlation, the MR effect is caused by competition between the field, spin interactions, and coupling to the magnetic lead. By extending the theory, we present a basis for operation of novel nanometer-size memories.

  6. Evidence of Formation of Superdense Nonmagnetic Cobalt

    Science.gov (United States)

    Banu, Nasrin; Singh, Surendra; Satpati, B.; Roy, A.; Basu, S.; Chakraborty, P.; Movva, Hema C. P.; Lauter, V.; Dev, B. N.

    2017-02-01

    Because of the presence of 3d transition metals in the Earth’s core, magnetism of these materials in their dense phases has been a topic of great interest. Theory predicts a dense face-centred-cubic phase of cobalt, which would be nonmagnetic. However, this dense nonmagnetic cobalt has not yet been observed. Recent investigations in thin film polycrystalline materials have shown the formation of compressive stress, which can increase the density of materials. We have discovered the existence of ultrathin superdense nonmagnetic cobalt layers in a polycrystalline cobalt thin film. The densities of these layers are about 1.2–1.4 times the normal density of Co. This has been revealed by X-ray reflectometry experiments, and corroborated by polarized neutron reflectometry (PNR) experiments. Transmission electron microscopy provides further evidence. The magnetic depth profile, obtained by PNR, shows that the superdense Co layers near the top of the film and at the film-substrate interface are nonmagnetic. The major part of the Co film has the usual density and magnetic moment. These results indicate the possibility of existence of nonmagnetic Co in the earth’s core under high pressure.

  7. Wheeled hopping robot

    Science.gov (United States)

    Fischer, Gary J [Albuquerque, NM

    2010-08-17

    The present invention provides robotic vehicles having wheeled and hopping mobilities that are capable of traversing (e.g. by hopping over) obstacles that are large in size relative to the robot and, are capable of operation in unpredictable terrain over long range. The present invention further provides combustion powered linear actuators, which can include latching mechanisms to facilitate pressurized fueling of the actuators, as can be used to provide wheeled vehicles with a hopping mobility.

  8. Effect of magnetic and nonmagnetic impurities (Ni, Zn) substitution for Cu in Bi{sub 2}(SrCa){sub 2+n}(Cu{sub 1{minus}x}M{sub x}){sub 1+n}O{sub y} whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Y.K.; Schneider, C.W.; Skove, M.J.; Nevitt, M.V.; Tessema, G.X. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); McGee, J.J. [Department of Geological Sciences, University of South Carolina, Columbia, South Carolina 29208 (United States)

    1997-09-01

    We have measured the change in the resistive T{sub c} of Bi{sub 2}(SrCa){sub 2+n}(Cu{sub 1{minus}x}M{sub x}){sub 1+n}O{sub y} whiskers due to substitution of M = Ni (magnetic) or M = Zn (nonmagnetic) for Cu. These whisker crystals show resistance drops for both the 2212 and 2223 (n=1,2) phases, with transition widths (10{endash}90{percent}) of 1 K. We checked the effect of oxygenation at several values of x, and found that T{sub c} is maximum for the y obtained by growing and annealing in 1 atm of O{sub 2}. We observed a linear depression of T{sub c} for both 2212 and 2223 phases with D=dT{sub c}/dx{approx}{minus}800 K for both Ni and Zn. This is in contrast with YBCO in which D{sub Zn}{approx}3D{sub Ni}. {copyright} {ital 1997} {ital The American Physical Society}

  9. EUVE Observations of Nonmagnetic Cataclysmic Variables

    Energy Technology Data Exchange (ETDEWEB)

    Mauche, C W

    2001-09-05

    The authors summarize EUVE's contribution to the study of the boundary layer emission of high accretion-rate nonmagnetic cataclysmic variables, especially the dwarf novae SS Cyg, U Gem, VW Hyi, and OY Car in outburst. They discuss the optical and EUV light curves of dwarf nova outbursts, the quasi-coherent oscillations of the EUV flux of SS Cyg, the EUV spectra of dwarf novae, and the future of EUV observations of cataclysmic variables.

  10. Hopping transport in solids

    CERN Document Server

    Pollak, M

    1991-01-01

    The hopping process, which differs substantially from conventional transport processes in crystals, is the central process in the transport phenomena discussed in this book. Throughout the book the term ``hopping'' is defined as the inelastic tunneling transfer of an electron between two localized electronic states centered at different locations. Such processes do not occur in conventional electronic transport in solids, since localized states are not compatible with the translational symmetry of crystals.The rapid growth of interest in hopping transport has followed in the footsteps of the

  11. Distribution Function of Mesoscopic Hopping Conductance

    Institute of Scientific and Technical Information of China (English)

    何立群; Eugene Kogan; ,Moshe Kaveh; Shlomo Havlin; Nehemia Schartz; LUO Dawei

    2002-01-01

    We study mesoscopic hopping conductance by computer simulation distribution functions (DFs). It is found that the distributions obtained by choosing randomly the chemical potentials (for a fixed impurity configuration), which corresponds to a typical experimental situation, coincide with those obtained when both impurity configuration and chemical potential are chosen randomly, in agreement with the ergodicity hypothesis. The DFs in shape obtained for one-dimensional systems are found to be quite close to the predictions of the theory by Raikh and Ruzin. For the two-dimensional case, the DFs both for a narrow system and thin film look to be similar (and close to the one-dimensional case). The DF for the conductance of the square sample is nearly Gaussian.

  12. Electrically-Generated Spin Polarization in Non-Magnetic Semiconductors

    Science.gov (United States)

    2016-03-31

    AFRL-AFOSR-VA-TR-2016-0143 Electrically -generated spin polarization in non-magnetic semiconductors Vanessa Sih UNIVERSITY OF MICHIGAN Final Report 03...SUBTITLE (YIP) - Electrically -generated spin polarization in non-magnetic semiconductors 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-12-1-0258 5c...that produced electrically -generated electron spin polarization in non-magnetic semiconductor heterostructures. Electrically -generated electron spin

  13. UXC55 Non-Magnetic Robot

    CERN Document Server

    Najjar, Tony

    2017-01-01

    As part of the collaboration between CMS and the Lebanese American University, we are looking into building a non-magnetic inspection rover capable of roaming around UXC55 and specifically under the detector. The robot should be specifically tailored and engineered to cope with the strong magnetic field in the cavern (300 G on average with peaks up to 1500 G) as well as other constraints such as flammability and geometry. Moreover, we are also taking part in the development of the instrumentation and wireless communication of the rover. The biggest challenge in setting up a non-magnetic rover lies in the actuation mechanism, in other words, getting it to move; motors are rotary actuators that rely on the concept of a rotor “trying to catch up” to a rotating magnetic field. We quickly realize the complication with using this popular technology; the strong field created by the CMS magnet greatly interferes with the motor, rendering it utterly stalled. Our approach, on the other hand, consists of using compl...

  14. HIP-HOP

    Institute of Scientific and Technical Information of China (English)

    QunyKing; 人在羽中; 钱李明

    2005-01-01

    自从一群摇滚青年开始跟风 Elvis 的《Blue SuedeShoes》风格,hip-hop 似乎就成为了全球最具影响力的音乐风格。它最初起源于美国的黑人和拉丁美洲人,之后迅速在全世界流行,成为80年代、90年代和新千年的主流音乐。无论是在广告界还是在电影业,从各类排行榜到各种酒吧,hip-hop 的影响逐年增加。在1997年,英国的 hip-hop 还只是一种地下音

  15. Superconductivity from correlated hopping

    CERN Document Server

    Batista, C D; Aligia, A A

    1995-01-01

    We consider a chain described by a next-nearest-neighbor hopping combined with a nearest-neighbor spin flip. In two dimensions this three-body term arises from a mapping of the three-band Hubbard model for CuO$_2$ planes to a generalized $t-J$ model and for large O-O hopping favors resonance-valence-bond superconductivity of predominantly $d$-wave symmetry. Solving the ground state and low-energy excitations by analytical and numerical methods we find that the chain is a Luther-Emery liquid with correlation exponent $K_{\\rho} = (2-n)^2/2$, where $n$ is the particle density.

  16. Effect of nonmagnetic and magnetic impurities on the specific heat jump in anisotropic superconductors

    NARCIS (Netherlands)

    Openov, LA

    The specific-heat jump DeltaC at a critical temperature T-c in an anisotropic superconductor containing both potential and spin-flip scatterers is calculated within a weak-coupling mean-field approximation. It is shown that the presence of even a small amount of spin-flip scatterers in the sample

  17. Current fluctuations in unconventional superconductor junctions with impurity scattering

    Science.gov (United States)

    Burset, Pablo; Lu, Bo; Tamura, Shun; Tanaka, Yukio

    2017-06-01

    The order parameter of bulk two-dimensional superconductors is classified as nodal if it vanishes for a direction in momentum space, or gapful if it does not. Each class can be topologically nontrivial if Andreev bound states are formed at the edges of the superconductor. Nonmagnetic impurities in the superconductor affect the formation of Andreev bound states and can drastically change the tunneling spectra for small voltages. Here, we investigate the mean current and its fluctuations for two-dimensional tunnel junctions between normal-metal and unconventional superconductors by solving the quasiclassical Eilenberger equation self-consistently, including the presence of nonmagnetic impurities in the superconductor. As the impurity strength increases, we find that superconductivity is suppressed for almost all order parameters since (i) at zero applied bias, the effective transferred charge calculated from the noise-current ratio tends to the electron charge e , and (ii) for finite bias, the current-voltage characteristics follows that of a normal-state junction. There are notable exceptions to this trend. First, gapful nontrivial (chiral) superconductors are very robust against impurity scattering due to the linear dispersion relation of their surface Andreev bound states. Second, for nodal nontrivial superconductors, only px-wave pairing is almost immune to the presence of impurities due to the emergence of odd-frequency s -wave Cooper pairs near the interface. Due to their anisotropic dependence on the wave vector, impurity scattering is an effective pair-breaking mechanism for the remaining nodal superconductors. All these behaviors are neatly captured by the noise-current ratio, providing a useful guide to find experimental signatures for unconventional superconductivity.

  18. Basin Hopping Graph

    DEFF Research Database (Denmark)

    Kucharik, Marcel; Hofacker, Ivo; Stadler, Peter

    2014-01-01

    Motivation RNA folding is a complicated kinetic process. The minimum free energy structure provides only a static view of the most stable conformational state of the system. It is insufficient to give detailed insights into the dynamic behavior of RNAs. A sufficiently sophisticated analysis...... of the folding free energy landscape, however, can provide the relevant information. Results We introduce the basin hopping graph (BHG) as a novel coarse-grained model of folding landscapes. Each vertex of the BHG is a local minimum, which represents the corresponding basin in the landscape. Its edges connect...

  19. Impurity- and magnetic-field-induced quasiparticle states in chiral p-wave superconductors

    Science.gov (United States)

    Guo, Yao-Wu; Li, Wei; Chen, Yan

    2017-10-01

    Both impurity- and magnetic-field-induced quasiparticle states in chiral p-wave superconductors are investigated theoretically by solving the Bogoliubov-de Gennes equations self-consistently. At the strong scattering limit, we find that a universal state bound to the impurity can be induced for both a single nonmagnetic impurity and a single magnetic impurity. Furthermore, we find that different chiral order parameters and the corresponding supercurrents have uniform distributions around linear impurities. Calculations of the local density of states in the presence of an external magnetic field show that the intensity peak of the zero-energy Majorana mode in the vortex core can be enhanced dramatically by tuning the strength of the external magnetic field or pairing interaction.

  20. How non-magnetic are "non-magnetic" Herbig Ae/Be stars?

    CERN Document Server

    Wade, G A; Catala, C; Bagnulo, S; Landstreet, J D; Flood, J; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Silvester, J

    2007-01-01

    Our recent discovery of magnetic fields in a small number of Herbig Ae/Be stars has required that we survey a much larger sample of stars. From our FORS1 and ESPaDOnS surveys, we have acquired about 125 observations of some 70 stars in which no magnetic fields are detected. Using a Monte Carlo approach, we have performed statistical comparisons of the observed longitudinal fields and LSD Stokes V profiles of these apparently non-magnetic stars with a variety of field models. This has allowed us to derive general upper limits on the presence of dipolar fields in the sample, and to place realistic upper limits on undetected dipole fields which may be present in individual stars. This paper briefly reports the results of the statistical modeling, as well as field upper limits for individual stars of particular interest.

  1. Magnetism without magnetic ions in non-magnetic perovskites SrTiO 3, SrZrO 3 and SrSnO 3

    Science.gov (United States)

    Bannikov, V. V.; Shein, I. R.; Kozhevnikov, V. L.; Ivanovskii, A. L.

    Using the full-potential linearized augmented plane-wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential, we studied spin polarization induced by replacement of oxygen atoms by non-magnetic 2p impurities (B, C and N) in non-magnetic cubic SrMO 3 perovskites, where M=Ti, Zr and Sn. The results show that the magnetization may appear because of the spin-split impurity bands inside the energy gap of the insulating SrMO 3 matrix. Large magnetic moments are found for the impurity centers. Smaller magnetic moments are induced on the oxygen atoms around impurities. It is shown that SrTiO 3:C and SrSnO 3:C should be magnetic semiconductors while other compounds in this series (SrTiO 3:B, SrTiO 3:N and SrZrO 3:C) are expected to exhibit magnetic half-metallic or pseudo-half-metallic properties.

  2. Magnetism without magnetic ions in non-magnetic perovskites SrTiO{sub 3}, SrZrO{sub 3} and SrSnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bannikov, V.V.; Shein, I.R.; Kozhevnikov, V.L. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620041 Ekaterinburg (Russian Federation); Ivanovskii, A.L. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620041 Ekaterinburg (Russian Federation)], E-mail: ivanovskii@ihim.uran.ru

    2008-03-15

    Using the full-potential linearized augmented plane-wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential, we studied spin polarization induced by replacement of oxygen atoms by non-magnetic 2p impurities (B, C and N) in non-magnetic cubic SrMO{sub 3} perovskites, where M=Ti, Zr and Sn. The results show that the magnetization may appear because of the spin-split impurity bands inside the energy gap of the insulating SrMO{sub 3} matrix. Large magnetic moments are found for the impurity centers. Smaller magnetic moments are induced on the oxygen atoms around impurities. It is shown that SrTiO{sub 3}:C and SrSnO{sub 3}:C should be magnetic semiconductors while other compounds in this series (SrTiO{sub 3}:B, SrTiO{sub 3}:N and SrZrO{sub 3}:C) are expected to exhibit magnetic half-metallic or pseudo-half-metallic properties.

  3. Lattice Gauge Quantum Simulation via State-Dependent Hopping

    DEFF Research Database (Denmark)

    Salami Dehkharghani, Amin

    2017-01-01

    We develop a quantum simulator architecture that is suitable for the simulation of U(1) Abelian gauge theories such as quantum electrodynamics. Our approach relies on the ability to control the hopping of a particle through a barrier by means of the internal quantum states of a neutral or charged...... impurity-particle sitting at the barrier. This scheme is highly experimentally feasible, as the correlated hopping does not require fine-tuning of the intra- and inter-species interactions. We investigate the applicability of the scheme in a double well potential, which is the basic building block...... of the simulator, both at the single-particle and the many-body mean-field level. Moreover, we evaluate its performance for different particle interactions and trapping, and, specifically for atom-ion systems, in the presence of micro-motion....

  4. Supercritical fluid extraction of hops

    Directory of Open Access Journals (Sweden)

    ZORAN ZEKOVIC

    2007-01-01

    Full Text Available Five cultivars of hop were extracted by the method of supercritical fluid extraction using carbon dioxide (SFE–CO2 as extractant. The extraction (50 g of hop sample using a CO2 flow rate of 97.725 L/h was done in the two steps: 1. extraction at 150 bar and 40°C for 2.5 h (sample of series A was obtained and, after that, the same sample of hop was extracted in the second step: 2. extraction at 300 bar and 40 °C for 2.5 h (sample of series B was obtained. The Magnum cultivar was chosen for the investigation of the extraction kinetics. For the qualitative and quantitative analysis of the obtained hop extracts, the GC-MS method was used. Two of four themost common compounds of hop aroma (a-humulene and b-caryophyllene were detected in samples of series A. In addition, isomerized a-acids and a high content of b-acids were detected. The a-acids content in the samples of series B was the highest in the extract of the Magnum cultivar (it is a bitter variety of hop. The low contents of a-acids in all the other hop samples resulted in extracts with low a-acids content, i.e., that contents were under the prescribed a-acids content.

  5. Suppression of Superfluid Density and the Pseudogap State in the Cuprates by Impurities.

    Science.gov (United States)

    Erdenemunkh, Unurbat; Koopman, Brian; Fu, Ling; Chatterjee, Kamalesh; Wise, W D; Gu, G D; Hudson, E W; Boyer, Michael C

    2016-12-16

    We use scanning tunneling microscopy (STM) to study magnetic Fe impurities intentionally doped into the high-temperature superconductor Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}. Our spectroscopic measurements reveal that Fe impurities introduce low-lying resonances in the density of states at Ω_{1}≈4  meV and Ω_{2}≈15  meV, allowing us to determine that, despite having a large magnetic moment, potential scattering of quasiparticles by Fe impurities dominates magnetic scattering. In addition, using high-resolution spatial characterizations of the local density of states near and away from Fe impurities, we detail the spatial extent of impurity-affected regions as well as provide a local view of impurity-induced effects on the superconducting and pseudogap states. Our studies of Fe impurities, when combined with a reinterpretation of earlier STM work in the context of a two-gap scenario, allow us to present a unified view of the atomic-scale effects of elemental impurities on the pseudogap and superconducting states in hole-doped cuprates; this may help resolve a previously assumed dichotomy between the effects of magnetic and nonmagnetic impurities in these materials.

  6. Hall effect in hopping regime

    Energy Technology Data Exchange (ETDEWEB)

    Avdonin, A., E-mail: avdonin@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Skupiński, P. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Grasza, K. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa (Poland); Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warszawa (Poland)

    2016-02-15

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO. - Highlights: • Expressions for Hall coefficient and mobility for hopping conductivity are derived. • Theoretical result is compared with experimental curves measured on ZnO. • Simultaneous action of free and hopping conduction channels is considered. • Non-linearity of hopping Hall coefficient is predicted.

  7. Design on hopping locomotion mechanism

    Institute of Scientific and Technical Information of China (English)

    LU Yong-kui; WU Yue-hua; YANG Jie; Hisayuki AOYAMA

    2005-01-01

    A new type of locomotion mechanism is introduced in this paper. With vibrating motors used in controling the movement of the hopping locomotion mechanism, the simple hopping locomotion mechanism had two motors, when the current went through the vertical motor, the vertical motor would vibrate to cause the mechanism to go forward, and when the current went through the horizontal motor, the mechanism will go around itself. A spring was added to the mechanism to change the natural frequency of the mechanism, when the frequency of the motor was equal to the natural frequency of the mechanism, the mechanism would hop resonantly. With the resonant hopping, the load of the mechanism was greatly enlarged, and some sensors could be added to the mechanism. Optical sensors were used to detect the infrared source, the current that went through the sensors related to the distance between the infrared light. Three optical sensors was put on the left, right and the front the mechanism, when the mechanism detect the special infrared source, it would turn itself to the light, and go forward to the light. The experiments of the mechanism shown that the mechanism could work well on different surfaces freely, and the resonant hopping locomotion mechanism with infrared sensors could move to the special light by automatic regulation. Experimental results and theoretical studies demonstrate that the innovative design for hopping locomotion mechanism is superior.

  8. Nanoscale Conductive Channels in Silicon Whiskers with Nickel Impurity

    Science.gov (United States)

    Yatsukhnenko, Serhii; Druzhinin, Anatoly; Ostrovskii, Igor; Khoverko, Yuriy; Chernetskiy, Mukhajlo

    2017-01-01

    The magnetization and magnetoresistance of Si whiskers doped with to boron concentrations corresponding to the metal-insulator transition (2 × 1018 cm-3 ÷ 5 × 1018 cm-3) were measured at high magnetic fields up to 14 T in a wide temperature range 4.2-300 K. Hysteresis of the magnetic moment was observed for Si p-type whiskers with nickel impurity in a wide temperature range 4.2-300 K indicating a strong interaction between the Ni impurities and the possibility of a magnetic cluster creation. The introduction of Ni impurity in Si whiskers leads to appearance and increase of the magnitude of negative magnetoresistance up to 10% as well as to the decrease of the whisker resistivity in the range of hopping conductance at low temperatures. The abovementioned effects were explained in the framework of appearance of magnetic polarons leading to modification of the conductive channels in the subsurface layers of the whiskers.

  9. Shiba chains of scalar impurities on unconventional superconductors

    Science.gov (United States)

    Neupert, Titus; Yazdani, A.; Bernevig, B. Andrei

    2016-03-01

    We show that a chain of nonmagnetic impurities deposited on a fully gapped two- or three-dimensional superconductor can become a topological one-dimensional superconductor with protected Majorana bound states at its end. A prerequisite is that the pairing potential of the underlying superconductor breaks the spin-rotation symmetry, as it is generically the case in systems with strong spin-orbit coupling. We illustrate this mechanism for a spinless triplet-superconductor (px+i py ) and a time-reversal symmetric Rashba superconductor with a mixture of singlet and triplet pairing. For the latter, we show that the impurity chain can be topologically nontrivial even if the underlying superconductor is topologically trivial.

  10. Effect of Born and unitary impurity scattering on the Kramer–Pesch shrinkage of a vortex core in an s-wave superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Nobuhiko, E-mail: n-hayashi@21c.osakafu-u.ac.jp [NanoSquare Research Center (N2RC), Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai 599-8570 (Japan); CREST(JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Higashi, Yoichi [NanoSquare Research Center (N2RC), Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai 599-8570 (Japan); Department of Mathematical Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531 (Japan); CREST(JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Nakai, Noriyuki; Suematsu, Hisataka [NanoSquare Research Center (N2RC), Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai 599-8570 (Japan); CREST(JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2013-01-15

    Highlights: ► We study non-magnetic impurity effect on a vortex in moderately clean regime. ► Impurity effect on s-wave vortex core in unitary limit is weaker than in Born one. ► Kramer–Pesch vortex core shrinkage is stronger in unitary limit than in Born one. -- Abstract: We theoretically investigate a non-magnetic impurity effect on the temperature dependence of the vortex core shrinkage (Kramer–Pesch effect) in a single-band s-wave superconductor. The Born limit and the unitary limit scattering are compared within the framework of the quasiclassical theory of superconductivity. We find that the impurity effect inside a vortex core in the unitary limit is weaker than in the Born one when a system is in the moderately clean regime, which results in a stronger core shrinkage in the unitary limit than in the Born one.

  11. Ferromagnetism and unconventional impurity effects in Rh- and Ga-doped LaCoO3

    Science.gov (United States)

    Asai, Shinichiro; Okazaki, Ryuji; Terasaki, Ichiro; Yasui, Yukio

    2014-03-01

    The perovskite oxide LaCoO3 has been long investigated because of a dramatic change of its spin state for Co3+ ions with temperature variation. The Co3+ ions (3d6) in LaCoO3 takes the non-magnetic low-spin state of t 2g6at low temperature. The spin state of the Co3+ ions in this system is sensitive to the chemical substitutions; we have found a weak ferromagnetism in a solid solution of LaCoO3 and LaRhO3 [S. Asai et al., JPSJ 80, 104705 (2011).]. Since the two oxides are non-magnetic at low temperature, our finding is an example of ``order by disorder,'' where a non-magnetic impurity makes a non-magnetic oxide ferromagnetic. We have further investigated the magnetization and x-ray diffraction of LaCo0 . 8 - yRh0.2MyO3 (M = Rh, Ga) [S. Asai et al., PRB 86, 014421 (2012).]. The magnetization decreases by the Ga3+ substitution much more drastically than by the Rh3+ substitution. It indicates that at least two kinds of Co3+ ions exist in LaCo0.8Rh0.2O3; one is nonmagnetic, and the other is magnetic. In this talk, we will also discuss the change of the lattice volume with the Rh3+ and Ga3+ substitution [S. Asai et al., JPSJ 82, 114606 (2013).].

  12. Superconducting Gap Symmetry of LaFeP(O,F Observed by Impurity Doping Effect

    Directory of Open Access Journals (Sweden)

    Shigeki Miyasaka

    2016-08-01

    Full Text Available We have investigated Mn, Co and Ni substitution effects on polycrystalline samples of LaFePO0.95F0.05 by resistivity and magnetoresistance measurements. In LaFe1-xMxPO0.95F0.05 (M = Mn, Co and Ni, the superconducting transition temperature (Tc monotonously decreases with increasing the impurity doping level of x. There is a clear difference of Tc suppression rates among Mn, Co and Ni doping cases, and the decreasing rate of Tc by Mn doping as a magnetic impurity is larger than those by the nonmagnetic doping impurities (Co/Ni. This result indicates that in LaFePO0.95F0.05, Tc is rapidly suppressed by the pair-breaking effect of magnetic impurities, and the pairing symmetry is a full-gapped s-wave. In the nonmagnetic impurity-doped systems, the residual resistivity in the normal state has nearly the same value when Tc becomes zero. The residual resistivity value is almost consistent with the universal value of sheet resistance for two-dimensional superconductors, suggesting that Tc is suppressed by electron localization in Co/Ni-doped LaFePO0.95F0.05.

  13. Effect of Born and unitary impurity scattering on the Kramer-Pesch shrinkage of a vortex core in a chiral p-wave superconductor

    Science.gov (United States)

    Hayashi, Nobuhiko; Kurosawa, Noriyuki; Arahata, Emiko; Kato, Yusuke; Tanuma, Yasunari; Tanaka, Yukio; Golubov, Alexander A.

    2013-11-01

    We theoretically investigate a non-magnetic impurity effect on the temperature dependence of the vortex core shrinkage (Kramer-Pesch effect) in a chiral p-wave superconductor. The Born limit and the unitary limit scattering are compared within the framework of the quasiclassical theory of superconductivity. We find that the robustness of the Kramer-Pesch effect against the impurity scattering in the Born limit is lost in the unitary limit.

  14. Supercritical carbon dioxide hop extraction

    Directory of Open Access Journals (Sweden)

    Pfaf-Šovljanski Ivana I.

    2005-01-01

    Full Text Available The hop of Magnum cultivar was extracted using supercritical carbon dioxide (SFE-as extractant. Extraction was carried out in the two steps: the first one being carried out at 150 bar and 40°C for 2.5 h (Extract A, and the second was the extraction of the same hop sample at 300 bar and 40°C for 2.5 h (Extract B. Extraction kinetics of the system hop-SFE-CO2 was investigated. Two of four most common compounds of hop aroma (α-humulene and β-caryophyllene were detected in Extract A. Isomerised α-acids and β-acids were detected too. a-Acid content in Extract B was high (that means it is a bitter variety of hop. Mathematical modeling using empirical model characteristic time model and simple single sphere model has been performed on Magnum cultivar extraction experimental results. Characteristic time model equations, best fitted experimental results. Empirical model equation, fitted results well, while simple single sphere model equation poorly approximated the results.

  15. Efficient implementation of the continuous-time hybridization expansion quantum impurity solver

    Science.gov (United States)

    Hafermann, Hartmut; Werner, Philipp; Gull, Emanuel

    2013-04-01

    Strongly correlated quantum impurity problems appear in a wide variety of contexts ranging from nanoscience and surface physics to material science and the theory of strongly correlated lattice models, where they appear as auxiliary systems within dynamical mean-field theory. Accurate and unbiased solutions must usually be obtained numerically, and continuous-time quantum Monte Carlo algorithms, a family of algorithms based on the stochastic sampling of partition function expansions, perform well for such systems. With the present paper we provide an efficient and generic implementation of the hybridization expansion quantum impurity solver, based on the segment representation. We provide a complete implementation featuring most of the recently developed extensions and optimizations. Our implementation allows one to treat retarded interactions and provides generalized measurement routines based on improved estimators for the self-energy and for vertex functions. The solver is embedded in the ALPS-DMFT application package. Catalogue identifier: AEOL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOL_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Use of the hybridization expansion impurity solvers requires citation of this paper. Use of any ALPS program requires citation of the ALPS [1] paper. No. of lines in distributed program, including test data, etc.: 650044 No. of bytes in distributed program, including test data, etc.: 20553265 Distribution format: tar.gz Programming language: C++/Python. Computer: Desktop PC, high-performance computers. Operating system: Unix, Linux, OSX, Windows. Has the code been vectorized or parallelized?: Yes, MPI parallelized. RAM: 1 GB Classification: 7.3. External routines: ALPS [1, 2, 3], BLAS [4, 5], LAPACK [6], HDF5 [7] Nature of problem: Quantum impurity models were originally introduced to describe a magnetic transition metal ion in a non-magnetic

  16. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions.

    Science.gov (United States)

    Zhang, Kun; Li, Huan-Huan; Grünberg, Peter; Li, Qiang; Ye, Sheng-Tao; Tian, Yu-Feng; Yan, Shi-Shen; Lin, Zhao-Jun; Kang, Shi-Shou; Chen, Yan-Xue; Liu, Guo-Lei; Mei, Liang-Mo

    2015-09-21

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices.

  17. Effect of Born and unitary impurity scattering on the Kramer-Pesch shrinkage of a vortex core in a chiral p-wave superconductor

    NARCIS (Netherlands)

    Hayashi, Nobuhiko; Kurosawa, Noriyuki; Arahata, Emiko; Kato, Yusuke; Tanuma, Yasunari; Tanaka, Yukio; Golubov, Alexander A.

    2013-01-01

    We theoretically investigate a non-magnetic impurity effect on the temperature dependence of the vortex core shrinkage (Kramer–Pesch effect) in a chiral p-wave superconductor. The Born limit and the unitary limit scattering are compared within the framework of the quasiclassical theory of supercondu

  18. Effect of Born and unitary impurity scattering on the Kramer-Pesch shrinkage of a vortex core in a chiral p-wave superconductor

    NARCIS (Netherlands)

    Hayashi, Nobuhiko; Kurosawa, Noriyuki; Arahata, Emiko; Kato, Yusuke; Tanuma, Yasunari; Tanaka, Yukio; Golubov, Alexandre Avraamovitch

    2013-01-01

    We theoretically investigate a non-magnetic impurity effect on the temperature dependence of the vortex core shrinkage (Kramer–Pesch effect) in a chiral p-wave superconductor. The Born limit and the unitary limit scattering are compared within the framework of the quasiclassical theory of

  19. Frequency hopping millimeter wave reflectometer

    Science.gov (United States)

    Cupido, L.; Sánchez, J.; Estrada, T.

    2004-10-01

    Reflectometry techniques are employed to study density fluctuations in fusion plasmas either using one channel or two channels with slightly different frequencies, to probe simultaneously closely spaced plasma layers (for radial correlation studies). The present article describes a novel system with increasing measuring capability utilizing only one single frequency that can be hopped during the discharge. This broadband fast hopping mm-wave reflectometer (BFHR) has been developed for both ASDEX upgrade (Max Plank Institute-Garching-Germany) and TJ-II stellarator (CIEMAT-Spain). The BFHR incorporates frequency synthesizers at microwave frequencies multiplied into the millimeter-wave range and uses heterodyne detection for sensitive phase and amplitude measurements.

  20. Controlling magnetism on metal surfaces with non-magnetic means: electric fields and surface charging.

    Science.gov (United States)

    Brovko, Oleg O; Ruiz-Díaz, Pedro; Dasa, Tamene R; Stepanyuk, Valeri S

    2014-03-01

    We review the state of the art of surface magnetic property control with non-magnetic means, concentrating on metallic surfaces and techniques such as charge-doping or external electric field (EEF) application. Magneto-electric coupling via EEF-based charge manipulation is discussed as a way to tailor single adatom spins, exchange interaction between adsorbates or anisotropies of layered systems. The mechanisms of paramagnetic and spin-dependent electric field screening and the effect thereof on surface magnetism are discussed in the framework of theoretical and experimental studies. The possibility to enhance the effect of EEF by immersing the target system into an electrolyte or ionic liquid is discussed by the example of substitutional impurities and metallic alloy multilayers. A similar physics is pointed out for the case of charge traps, metallic systems decoupled from a bulk electron bath. In that case the charging provides the charge carrier density changes necessary to affect the magnetic moments and anisotropies in the system. Finally, the option of using quasi-free electrons rather than localized atomic spins for surface magnetism control is discussed with the example of Shockley-type metallic surface states confined to magnetic nanoislands.

  1. Degradation of topological surface state by nonmagnetic S doping in SrxBi2Se3

    Science.gov (United States)

    Huang, Hui; Gu, Juanjuan; Tan, Min; Wang, Qinglong; Ji, Ping; Hu, Xueyou

    2017-01-01

    Research on possible topological superconductivity has grown rapidly over the past several years, from fundamental studies to the development of next generation technologies. Recently, it has been reported that the SrxBi2Se3 exhibits superconductivity with topological surface state, making this compound a promising candidate for investigating possible topological superconductivity. However, whether or not the topological surface state is robust against impurities is not clear in this system. Here we report a detailed investigation on the lattice structure, electronic and magnetic properties, as well as the topological superconducting properties of SrxBi2Se3−ySy samples. It is found that the superconducting transition temperature keeps nearly unchanged in all samples, despite of a gradual decrease of the superconducting shielding volume fraction with increasing S doping content. Meanwhile, the Shubnikov-de Hass oscillation results of the SrxBi2Se3−ySy samples reveal that the topological surface states are destroyed in S doped samples, suggesting the topological character is degraded by nonmagnetic dopants. PMID:28358021

  2. Hip-Hop Pop Art

    Science.gov (United States)

    Talley, Clarence, Sr.

    2011-01-01

    Art has a way of helping students better understand and appreciate the world around them, particularly the things that are most important to them. Hip hop is one of those generational genres that capture the attention of young students like few other things do. Drawing on this genre to get students to create art is an excellent way to demonstrate…

  3. Hip-Hop Pop Art

    Science.gov (United States)

    Talley, Clarence, Sr.

    2011-01-01

    Art has a way of helping students better understand and appreciate the world around them, particularly the things that are most important to them. Hip hop is one of those generational genres that capture the attention of young students like few other things do. Drawing on this genre to get students to create art is an excellent way to demonstrate…

  4. Influence of nonmagnetic disorder on specific heat and electrical resistivity in Kondo lattice system CePd{sub 1−x}Ge{sub x}In

    Energy Technology Data Exchange (ETDEWEB)

    Gnida, D., E-mail: d.gnida@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wrocław (Poland); Dominyuk, N.; Zaremba, V. [Inorganic Chemistry Department, Ivan Franko Lviv National University, Kyryla and Mephodiya Str. 6, 79005 Lviv (Ukraine); Kaczorowski, D. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wrocław (Poland)

    2015-02-15

    Highlights: • Interplay of Kondo and RKKY interactions in the presence of nonmagnetic disorder. • Suppression of the coherent Kondo state by nonmagnetic impurities. • Observation of quantum interference phenomena in Ce-based Kondo system. • Coexistence of incoherent Kondo effect and Altshuler-Aronov quantum correction. - Abstract: The alloy system CePd{sub 1−x}Ge{sub x}In with 0.1⩽x⩽0.4 was investigated by means of heat capacity and electrical resistivity measurements. Its low-temperature behavior has been found to be governed by the interplay of Kondo effect and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions in the presence of atomic disorder in nonmagnetic atoms sublattice. The coherent Kondo state, observed for CePdIn, gradually vanishes with increasing the Ge-content. The incoherent Kondo state, which characterizes Ge-rich alloys, appears very sensitive to applied magnetic field. The observed systematic changes in the temperature- and field-dependent electrical transport in CePd{sub 1−x}Ge{sub x}In manifest the important role of quantum correction due to electron-electron interactions in weakly localized regime.

  5. Interstitial impurity-induced magnetism in α-PbO surface.

    Science.gov (United States)

    Arguelles, E; Amino, S; Aspera, S; Nakanishi, H; Kasai, H

    2015-01-14

    We have investigated the effects of 3d transition metal (TM) and non-magnetic interstitial impurities in α-PbO (0 0 1) surface using ab-initio calculations. The calculated impurity-induced magnetic moments are 2.25 μB, 3.11 μB and 0.94 μB for Fe, Mn and Pb interstitials respectively. In the bonding process, TM's lower energy lying d(z2) states form overlaps with nearest neighbour oxygen atoms' p(z) states, with other non-bonding spin split d states situated near or at the Fermi level. These spin split orbitals introduce spin polarised p impurity states of oxygen atoms near the surface.

  6. Hopping models and ac universality

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Schrøder, Thomas

    2002-01-01

    Some general relations for hopping models are established. We proceed to discuss the universality of the ac conductivity which arises in the extreme disorder limit of the random barrier model. It is shown that the relevant dimension entering into the diffusion cluster approximation (DCA) is the h......) is the harmonic (fracton) dimension of the diffusion cluster. The temperature scaling of the dimensionless frequency entering into the DCA is discussed. Finally, some open problems regarding ac universality are listed.......Some general relations for hopping models are established. We proceed to discuss the universality of the ac conductivity which arises in the extreme disorder limit of the random barrier model. It is shown that the relevant dimension entering into the diffusion cluster approximation (DCA...

  7. Impurity solitons with quadratic nonlinearities

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Torres, Juan P-; Torner, Lluis

    1998-01-01

    We fmd families of solitary waves mediated by parametric mixing in quadratic nonlinear media that are localized at point-defect impurities. Solitons localized at attractive impurities are found to be dynamically stable. It is shown that localization at the impurity modifies strongly the soliton p...

  8. Nuclear conversion theory: molecular hydrogen in non-magnetic insulators

    Science.gov (United States)

    Ilisca, Ernest; Ghiglieno, Filippo

    2016-09-01

    The hydrogen conversion patterns on non-magnetic solids sensitively depend upon the degree of singlet/triplet mixing in the intermediates of the catalytic reaction. Three main `symmetry-breaking' interactions are brought together. In a typical channel, the electron spin-orbit (SO) couplings introduce some magnetic excitations in the non-magnetic solid ground state. The electron spin is exchanged with a molecular one by the electric molecule-solid electron repulsion, mixing the bonding and antibonding states and affecting the molecule rotation. Finally, the magnetic hyperfine contact transfers the electron spin angular momentum to the nuclei. Two families of channels are considered and a simple criterion based on the SO coupling strength is proposed to select the most efficient one. The denoted `electronic' conversion path involves an emission of excitons that propagate and disintegrate in the bulk. In the other denoted `nuclear', the excited electron states are transients of a loop, and the electron system returns to its fundamental ground state. The described model enlarges previous studies by extending the electron basis to charge-transfer states and `continui' of band states, and focuses on the broadening of the antibonding molecular excited state by the solid conduction band that provides efficient tunnelling paths for the hydrogen conversion. After working out the general conversion algebra, the conversion rates of hydrogen on insulating and semiconductor solids are related to a few molecule-solid parameters (gap width, ionization and affinity potentials) and compared with experimental measures.

  9. THE IMPURITY OF SCIENCE

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1962-04-19

    Science is impure in two ways. There is not a 'pure' science. By this I mean that physics impinges on astronomy, on the one hand, and chemistry on biology on the other. And not only does each support its neighbors but derives sustenance from them. The same can be said of chemistry. Biology is, perhaps, the example par excellence today of an 'impure' science. Beyond this, there is no 'pure' science itself divorced from human values. The importance of science to the humanities and the humanities to science in their complementary contribution to the variety of human life grows daily. The need for men familiar with both is imperative. We are faced today with a social decision resulting from our progress in molecular genetics at least equal to, and probably greater than, that required of us twenty years ago with the maturity of nuclear power.

  10. Transport signatures of Kondo physics and quantum criticality in graphene with magnetic impurities

    Science.gov (United States)

    Ruiz-Tijerina, David A.; Dias da Silva, Luis G. G. V.

    2017-03-01

    Localized magnetic moments have been predicted to develop in graphene samples with vacancies or adsorbates. The interplay between such magnetic impurities and graphene's Dirac quasiparticles leads to remarkable many-body phenomena, which have, so far, proved elusive to experimental efforts. In this article we study the thermodynamic, spectral, and transport signatures of quantum criticality and Kondo physics of a dilute ensemble of atomic impurities in graphene. We consider vacancies and adatoms that either break or preserve graphene's C3 v and inversion symmetries. In a neutral graphene sample, all cases display symmetry-dependent quantum criticality, leading to enhanced impurity scattering for asymmetric impurities, in a manner analogous to bound-state formation by nonmagnetic resonant scatterers. Kondo correlations emerge only in the presence of a back gate, with estimated Kondo temperatures well within the experimentally accessible domain for all impurity types. For symmetry-breaking impurities at charge neutrality, quantum criticality is signaled by T-2 resistivity scaling, leading to full insulating behavior at low temperatures, while low-temperature resistivity plateaus appear both in the noncritical and Kondo regimes. By contrast, the resistivity contribution from symmetric vacancies and hollow-site adsorbates vanishes at charge neutrality and for arbitrary back-gate voltages, respectively. This implies that local probing methods are required for the detection of both Kondo and quantum critical signatures in these symmetry-preserving cases.

  11. Fundamentals of beer and hop chemistry

    OpenAIRE

    Denis de Keukeleire

    2000-01-01

    Beer brewing is an intricate process encompassing mixing and further elaboration of four essential raw materials, including barley malt, brewing water, hops and yeast. Particularly hops determine to a great extent typical beer qualities such as bitter taste, hoppy flavour, and foam stability. Conversely, hop-derived bitter acids account for an offending lightstruck flavour, which is formed on exposure of beer to light. These various processes are presented in detail, while due emphasis is pla...

  12. Fundamentals of beer and hop chemistry

    Directory of Open Access Journals (Sweden)

    Denis De Keukeleire

    2000-02-01

    Full Text Available Beer brewing is an intricate process encompassing mixing and further elaboration of four essential raw materials, including barley malt, brewing water, hops and yeast. Particularly hops determine to a great extent typical beer qualities such as bitter taste, hoppy flavour, and foam stability. Conversely, hop-derived bitter acids account for an offending lightstruck flavour, which is formed on exposure of beer to light. These various processes are presented in detail, while due emphasis is placed on state-of-the-art hop technology, which provides brewers with efficient means to control bitterness, foam, and light-stability thereby allowing for the production of beers with consistent quality.

  13. Routing for wireless multi-hop networks

    CERN Document Server

    Hamid, Sherin Abdel; Takahara, Glen

    2013-01-01

    The focus of this brief is to identify what unifies and what distinguishes the routing functions in four wireless multi-hop network paradigms. The brief introduces a generic routing model that can be used as a foundation of wireless multi-hop routing protocol analysis and design. It demonstrates that such model can be adopted by any wireless multi-hop routing protocol. Also presented is a glimpse of the ideal wireless multi-hop routing protocol along with several open issues.

  14. Magnetic Nanoparticles in Non-magnetic CNTs and Graphene

    Science.gov (United States)

    Kayondo, Moses; Seifu, Dereje

    Magnetic nanoparticles were embedded in non-magnetic CNTs and graphene matrix to incorporate all the advantages and the unique properties of CNTs and graphene. Composites of CNTs and graphene with magnetic nanoparticles may offer new opportunities for a wide variety of potential applications such as magnetic data storage, magnetic force microscopy tip, electromagnetic interference shields, thermally conductive films, reinforced polymer composites, transparent electrodes for displays, solar cells, gas sensors, magnetic nanofluids, and magnetically guided drug delivery systems. Magnetic nanoparticles coated CNTs can also be used as an electrode in lithium ion battery to replace graphite because of the higher theoretical capacity. Graphene nanocomposites, coated with magnetic sensitive nanoparticles, have demonstrated enhanced magnetic property. We would like to acknowledge support by NSF-MRI-DMR-1337339.

  15. Hop-by-HopWorm Propagation with Carryover Epidemic Model in Mobile Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jun-Won Ho

    2015-10-01

    Full Text Available In the internet, a worm is usually propagated in a random multi-hop contact manner. However, the attacker will not likely select this random multi-hop propagation approach in a mobile sensor network. This is because multi-hop worm route paths to random vulnerable targets can be often breached due to node mobility, leading to failure of fast worm spread under this strategy. Therefore, an appropriate propagation strategy is needed for mobile sensor worms. To meet this need, we discuss a hop-by-hop worm propagation model in mobile sensor networks. In a hop-by-hop worm propagation model, benign nodes are infected by worm in neighbor-to-neighbor spread manner. Since worm infection occurs in hop-by-hop contact, it is not substantially affected by a route breach incurred by node mobility. We also propose the carryover epidemic model to deal with the worm infection quota deficiency that might occur when employing an epidemic model in a mobile sensor network. We analyze worm infection capability under the carryover epidemic model. Moreover, we simulate hop-by-hop worm propagation with carryover epidemic model by using an ns-2 simulator. The simulation results demonstrate that infection quota carryovers are seldom observed where a node’s maximum speed is no less than 20 m/s.

  16. How Does a Hopping Kangaroo Breathe?

    Science.gov (United States)

    Giuliodori, Mauricio J.; Lujan, Heidi L.; Janbaih, Hussein; DiCarlo, Stephen E.

    2010-01-01

    We developed a model to demonstrate how a hopping kangaroo breathes. Interestingly, a kangaroo uses less energy to breathe while hopping than while standing still. This occurs, in part, because rather than using muscle power to move air into and out of the lungs, air is pulled into (inspiration) and pushed out of (expiration) the lungs as the…

  17. Hip-hop and urban studies

    NARCIS (Netherlands)

    Jaffe, R.

    2014-01-01

    How can urban studies research engage fruitfully with hip-hop? This contribution responds to the essays by David Beer and Martin Lamotte on ‘street music’, urban ethnography and ghettoized communities. It discusses how a social science engagement with hip-hop texts might differ from cultural studies

  18. Pertunjukan Teater Karo Hip Hop Kontemporer KAI

    Directory of Open Access Journals (Sweden)

    Silvia Anggreni Purba

    2013-11-01

    Full Text Available Pertunjukan ini berawal dari sebuah ide untuk mengkolaborasikan tradisi Karo dengan budaya populer. Dengan cara seperti ini pertunjukan bisa dinikmati tanpa batasan bahasa dan budaya. Proses menggabungkan dua budaya yang berbeda merupakan bentuk budaya hibrida dan terjadi akibat proses globalisasi. Melalui proses pengendapan pengamatan dan kesan yang kuat, pertunjukan ini dibawa ke dalam bentuk Hip Hop. Pertunjukan ini merupakan bagian dari sebuah tragedi modern dengan karakter destruktif, mengeksplorasi emosi dan menyampaikannya kepada penonton. Eksplorasi budaya Karo dan tari Hip Hop sebagai bahasa simbol mampu memperkuat kata-kata. Gerak tidak diungkapkan dengan kata lisan tetapi disajikan melalui gerak tari Hip Hop. Penafsiran legenda dan teks ke dalam gerak, melalui proses pelatihan di laboratorium sebagai proses pencarian dan eksperimentasi diwujudkan dengan mempertimbangkan unsur-unsur dasar dari Hip Hop, unsur budaya Karo dan tontonan. Karo Hip Hop diharapkan menjadi bentuk estetika teater modern yang diinginkan tanpa kehilangan tradisi.Kata kunci: Tari Karo kontemporer, Hip-hop, budaya hibridaABSTRACTPertunjukan Teater Karo Hip Hop Kontemporer KAI. The performance of Karo Theater collaborated with Hip Hop stems from a simple idea to collaborate Karo cultural traditions with popular culture. The performances can be enjoyed without having limitation on the language and culture. The process of combining two different cultures is a form of hybrid culture, and it may occur due to the globalization process. Through the process of deposition of the observations and strong impression, this performance is then brought into the form of Hip Hop as a preferred form which is energetic, personal and global. This performance is part of a modern tragedy with its destructive character which has explored the emotion and has presented it to the audiences. The exploration of Karo cultural tradition and Hip Hop dance as a language of symbols is able to

  19. Investigation of giant magnetoconductance in organic devices based on hopping mechanism

    Science.gov (United States)

    Yang, F. J.; Qin, W.; Xie, S. J.

    2014-04-01

    We suggest a spin-dependent hopping mechanism which includes the effect of the external magnetic field as well as hyperfine interaction (HFI) to explain the observed giant magnetoconductance (MC) in non-magnetic organic devices. Based on the extended Marcus theory, we calculate the MC by using the master equation. It is found that a MC value as large as 91% is obtained under a low driving voltage. For suitable parameters, the theoretical results are in good agreement with the experimental data. Influences of the carrier density, HFI, and the carrier localization on the MC value are investigated. Especially, it is found that a low-dimensional structure of the organic materials is favorable to get a large MC value.

  20. Impurity sources in TEXTOR

    Science.gov (United States)

    Pospieszczyk, A.; Bay, H. L.; Bogen, P.; Hartwig, H.; Hintz, E.; Konen, L.; Ross, G. G.; Rusbuldt, D.; Samm, U.; Schweer, B.

    1987-02-01

    The deuterium, oxygen and carbon fluxes from the main limiter and the deuterium fluxes from the wall are measured in TEXTOR for an "all carbon" surrounding as a function of central density ne, of applied ICRH-power and of different wall conditions (carbonization). For this purpose, emission spectroscopy both with filter systems and spectrometers has been used. It is found that a major release mechanism for light impurities is via the formation of molecules. Oxygen seems to enter the discharge from the liner via O-D containing molecules, whereas the limiter acts as the main carbon source by the release of hydro-carbons as indicated by the observed CD-band spectra. Both oxygen and carbon fluxes are reduced by about a factor of two after a fresh carbonization. Above a certain critical density the plasma detaches from the limiter and forms a stable discharge with a radiation cooled boundary layer and with a major fraction of particles now reaching the wall instead of the limiter. The critical density rises with decreasing impurity fluxes or with increasing heating powers.

  1. Inductive sensor to detect metal impurities in non-metallic medium

    Science.gov (United States)

    Bykovsky, N. A.; Puchkova, L. N.; Fanakova, N. N.

    2017-02-01

    The mathematical model for an induction detector intended for detection of metal impurities is examined. The detector consists of three coils. The centre coil serves to induct a magnetic moment in the metal sample, and side coils are used to record this moment during the sample propulsion through the detector. It is shown that at an identical value of the magnetic field induction, created by the induction coil in the unit volume of the sample, the induced magnetic moment is defined by magnetic susceptibility for ferromagnetics, and for nonmagnetic materials – by their electric conductivity.

  2. Size effect on high temperature variable range hopping in Al+ implanted 4H-SiC

    Science.gov (United States)

    Parisini, Antonella; Parisini, Andrea; Nipoti, Roberta

    2017-01-01

    The hole transport properties of heavily doped 4H-SiC (Al) layers with Al implanted concentrations of 3  ×  1020 and 5  ×  1020 cm-3 and annealed in the temperature range 1950-2100 °C, have been analyzed to determine the main transport mechanisms. This study shows that the temperature dependence of the resistivity (conductivity) may be accounted for by a variable range hopping (VRH) transport into an impurity band. Depending on the concentration of the implanted impurities and the post-implantation annealing treatment, this VRH mechanism persists over different temperature ranges that may extend up to room temperature. In this framework, two different transport regimes are identified, having the characteristic of an isotropic 3D VRH and an anisotropic nearly 2D VRH. The latter conduction mechanism appears to take place in a rather thick layer (about 400 nm) that is too large to induce a confinement effect of the carrier hops. The possibility that an anisotropic transport may be induced by a structural modification of the implanted layer because of a high density of basal plane stacking faults (SF) in the implanted layers is considered. The interpretation of the conduction in the heaviest doped samples in terms of nearly 2D VRH is supported by the results of the transmission electron microscopy (TEM) investigation on one of the 5  ×  1020 cm-3 Al implanted samples of this study. In this context, the average separation between basal plane SFs, measured along the c-axis, which is orthogonal to the carrier transport during electrical characterization, appears to be in keeping with the estimated value of the optimal hopping length of the VRH theory. Conversely, no SFs are detected by TEM in a sample with an Al concentration of 1  ×  1019 cm-3 where a 3D nearest neighbor hopping (NNH) transport is observed.

  3. Nerve Conduction Through Dendrites via Proton Hopping.

    Science.gov (United States)

    Kier, Lemont B

    2017-01-01

    In our previous studies of nerve conduction conducted by proton hopping, we have considered the axon, soma, synapse and the nodes of Ranvier. The role of proton hopping described the passage of information through each of these units of a typical nerve system. The synapse projects information from the axon to the dendrite and their associated spines. We have invoked the passage of protons via a hopping mechanism to illustrate the continuum of the impulse through the system, via the soma following the dendrites. This is proposed to be a continuum invoked by the proton hopping method. With the proposal of the activity through the dendrites, via proton hopping, a complete model of the nerve function is invoked. At each step to the way, a water pathway is present and is invoked in the proposed model as the carrier of the message via proton hopping. The importance of the dendrites is evident by the presence of a vast number of spines, each possessing the possibility to carry unique messages through the nervous system. With this model of the role of dendrites, functioning with the presence of proton hopping, a complete model of the nerve system is presented. The validity of this model will be available for further studies and models to assess it's validity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Colloidal self assembly of non-magnetic particles in magnetic nanofluid

    Science.gov (United States)

    Jadav, Mudra; Patel, Rajesh

    2015-06-01

    Here we present a technique using magnetic nanofluid to induce bidispersed suspension of nonmagnetic particles to assemble into colloidal chain, triangle, rectangle, ring-flower configurations. By changing the amplitude and direction of the magnetic field, we could tune the structure of nonmagnetic particles in magnetic nanofluid. The structures are assembled using magneto static interactions between effectively nonmagnetic particles dispersed in magnetizable magnetic nanofluid. The assembly of complex structures out of simple colloidal building blocks is of practical interest in photonic crystals and DNA biosensors.

  5. Colloidal self assembly of non-magnetic particles in magnetic nanofluid

    Energy Technology Data Exchange (ETDEWEB)

    Jadav, Mudra; Patel, Rajesh, E-mail: rjp@mkbhavuni.edu.in, E-mail: rpat7@yahoo.co [Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar-364002 (India)

    2015-06-24

    Here we present a technique using magnetic nanofluid to induce bidispersed suspension of nonmagnetic particles to assemble into colloidal chain, triangle, rectangle, ring-flower configurations. By changing the amplitude and direction of the magnetic field, we could tune the structure of nonmagnetic particles in magnetic nanofluid. The structures are assembled using magneto static interactions between effectively nonmagnetic particles dispersed in magnetizable magnetic nanofluid. The assembly of complex structures out of simple colloidal building blocks is of practical interest in photonic crystals and DNA biosensors.

  6. Giant spin Seebeck effect in a non-magnetic material.

    Science.gov (United States)

    Jaworski, C M; Myers, R C; Johnston-Halperin, E; Heremans, J P

    2012-07-11

    The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals, semiconductors and insulators. Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of ∼25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values.

  7. Quantum anomalous Hall effect in stanene on a nonmagnetic substrate

    Science.gov (United States)

    Zhang, Huisheng; Zhou, Tong; Zhang, Jiayong; Zhao, Bao; Yao, Yugui; Yang, Zhongqin

    2016-12-01

    Since the quantum anomalous Hall (QAH) effect was realized in magnetic topological insulators, research on the effect has become a hot topic. The very harsh realizing requirements of the effect in experiments, however, hinder its practical applications. Based on ab initio methods, we find that nonmagnetic Pb I2 films are ideal substrates for the two-dimensional honeycomb stanene. The QAH effect with a pretty large band gap (up to 90 meV) can be achieved in the functionalized stanene /Pb I2 heterostructure. Despite van der Waals interactions in the heterostructure, band inversions are found to be happening between Sn (s and px ,y ) and Pb (px ,y) orbitals, playing a key role in determining the nontrivial topology and the large band gap of the system. Having no magnetic atoms is imperative to triggering the QAH effect. A very stable rudimentary device having QAH effects is proposed based on the Sn /Pb I2 heterostructure. Our results demonstrate that QAH effects can be easily realized in the Sn /Pb I2 heterostructures in experiments.

  8. Steerable Hopping Six-Legged Robot

    Science.gov (United States)

    Younse, Paulo; Aghazarian, Hrand

    2010-01-01

    The figure depicts selected aspects of a six-legged robot that moves by hopping and that can be steered in the sense that it can be launched into a hop in a controllable direction. This is a prototype of hopping robots being developed for use in scientific exploration of rough terrain on remote planets that have surface gravitation less than that of Earth. Hopping robots could also be used on Earth, albeit at diminished hopping distances associated with the greater Earth gravitation. The upper end of each leg is connected through two universal joints to an upper and a lower hexagonal frame, such that the tilt of the leg depends on the relative position of the two frames. Two non-back-driveable worm-gear motor drives are used to control the relative position of the two frames along two axes 120 apart, thereby controlling the common tilt of all six legs and thereby, further, controlling the direction of hopping. Each leg includes an upper and a lower aluminum frame segment with a joint between them. A fiberglass spring, connected via hinges to both segments, is used to store hopping energy prior to launch into a hop and to cushion the landing at the end of the hop. A cable for loading the spring is run into each leg through the center of the universal joints and then down along the center lines of the segments to the lower end of the leg. A central spool actuated by a motor with a harmonic drive and an electromagnetic clutch winds in all six cables to compress all six springs (thereby also flexing all six legs) simultaneously. To ensure that all the legs push off and land in the same direction, timing- belt pulley drives are attached to the leg segments, restricting the flexing and extension of all six legs to a common linear motion. In preparation for a hop, the spool can be driven to load the spring legs by an amount corresponding to a desired hop distance within range. The amount of compression can be computed from the reading of a shaft-angle encoder that

  9. Impurity effect on Kramer-Pesch core shrinkage in s-wave vortex and chiral p-wave vortex

    Science.gov (United States)

    Hayashi, Nobuhiko; Kato, Yusuke; Sigrist, Manfred

    2005-04-01

    The low-temperature shrinking of the vortex core (Kramer-Pesch effect) is studied for an isolated single vortex for chiral p-wave and s-wave superconducting phases. The effect of nonmagnetic impurities on the vortex core radius is numerically investigated in the Born limit by means of a quasiclassical approach. It is shown that in the chiral p-wave phase the Kramer-Pesch effect displays a certain robustness against impurities owing to a specific quantum effect, while the s-wave phase reacts more sensitively to impurity scattering. This suggests chiral p-wave superconductors as promising candidates for the experimental observation of the Kramer-Pesch effect.

  10. Competing effects of magnetic impurities in the anomalous Hall effect on the surface of a topological insulator

    Science.gov (United States)

    Deng, Ming-Xun; Luo, Wei; Deng, W. Y.; Chen, M. N.; Sheng, L.; Xing, D. Y.

    2016-12-01

    We investigate the anomalous Hall effect (AHE) on the surface of a topological insulator induced by a finite concentration of magnetic impurities, and find topologically nontrivial and trivial mechanisms simultaneously contributing to the Hall conductivity. In the topologically nontrivial mechanism, the impurities gap the surface spectrum and result in a half-integer quantized intrinsic Hall conductivity in units e2/h , while in the topologically trivial mechanism, the half-integer quantized plateau is modified by impurity-induced localized states via a gap-filling process. The nonmagnetic charge potential itself, though participating in the gap-filling process, cannot induce the AHE. In the presence of a finite magnetic potential, the charge potential would destroy the symmetric distribution of the Hall conductivity by redistributing the localized levels. More interestingly, the sign of the Hall conductivity is tunable by changing the strength of the charge potential.

  11. Magnetic susceptibility of Dirac fermions, Bi-Sb alloys, interacting Bloch fermions, dilute nonmagnetic alloys, and Kondo alloys

    Science.gov (United States)

    Buot, Felix A.; Otadoy, Roland E. S.; Rivero, Karla B.

    2017-03-01

    Wide ranging interest in Dirac Hamiltonian is due to the emergence of novel materials, namely, graphene, topological insulators and superconductors, the newly-discovered Weyl semimetals, and still actively-sought after Majorana fermions in real materials. We give a brief review of the relativistic Dirac quantum mechanics and its impact in the developments of modern physics. The quantum band dynamics of Dirac Hamiltonian is crucial in resolving the giant diamagnetism of bismuth and Bi-Sb alloys. Quantitative agreement of the theory with the experiments on Bi-Sb alloys has been achieved, and physically meaningful contributions to the diamagnetism has been identified. We also treat relativistic Dirac fermion as an interband dynamics in uniform magnetic fields. For the interacting Bloch electrons, the role of translation symmetry for calculating the magnetic susceptibility avoids any approximation to second order in the field. The expressions for magnetic susceptibility of dilute nonmagnetic alloys give a firm theoretical foundation of the empirical formulas used in fitting experimental results. The unified treatment of all the above calculations is based on the lattice Weyl-Wigner formulation of discrete phase-space quantum mechanics. For completeness, the magnetic susceptibility of Kondo alloys is also given since Dirac fermions in conduction band and magnetic impurities exhibit Kondo effect.

  12. Helicobacter pylori HopE and HopV porins present scarce expression among clinical isolates

    Institute of Scientific and Technical Information of China (English)

    Maritza; Lienlaf; Juan; Pablo; Morales; María; Inés; Díaz; Rodrigo; Díaz; Elsa; Bruce; Freddy; Siegel; Gloria; León; Paul; R; Harris; Alejandro; Venegas

    2010-01-01

    AIM:To evaluate how widely Helicobacter pylori (H. pylori ) HopE and HopV porins are expressed among Chilean isolates and how seroprevalent they are among infected patients in Chile.METHODS: H. pylori hopE and hopV genes derived from strain CHCTX-1 were cloned by polymerase chain reaction (PCR), sequenced and expressed in Escherichia coli AD494 (DE3). Gel-purified porins were used to prepare polyclonal antibodies. The presence of both genes was tested by PCR in a collection of H. pylori clinical isolates an...

  13. Hip-hop, Onegin - pop! / Tatjana Aleksandrova

    Index Scriptorium Estoniae

    Aleksandrova, Tatjana, 1945-

    2004-01-01

    Erateatrikooli KS, mida juhib Svetlana Krassman, lavastus A. Pushkini poeemi "Jevgeni Onegin" motiividel. Noortelavastuse muusikalises seades kasutatakse klassikalise muusika aranzheeringuid ja räppi, kostüümidraamat koos hip-hop rõivastiiliga

  14. Hip-hop, Onegin - pop! / Tatjana Aleksandrova

    Index Scriptorium Estoniae

    Aleksandrova, Tatjana, 1945-

    2004-01-01

    Erateatrikooli KS, mida juhib Svetlana Krassman, lavastus A. Pushkini poeemi "Jevgeni Onegin" motiividel. Noortelavastuse muusikalises seades kasutatakse klassikalise muusika aranzheeringuid ja räppi, kostüümidraamat koos hip-hop rõivastiiliga

  15. Effect of Born and unitary impurity scattering on the Kramer-Pesch shrinkage of a vortex core in an s-wave superconductor

    Science.gov (United States)

    Hayashi, Nobuhiko; Higashi, Yoichi; Nakai, Noriyuki; Suematsu, Hisataka

    2013-01-01

    We theoretically investigate a non-magnetic impurity effect on the temperature dependence of the vortex core shrinkage (Kramer-Pesch effect) in a single-band s-wave superconductor. The Born limit and the unitary limit scattering are compared within the framework of the quasiclassical theory of superconductivity. We find that the impurity effect inside a vortex core in the unitary limit is weaker than in the Born one when a system is in the moderately clean regime, which results in a stronger core shrinkage in the unitary limit than in the Born one.

  16. Effect of Born and unitary impurity scattering on the Kramer–Pesch shrinkage of a vortex core in a chiral p-wave superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Nobuhiko, E-mail: n-hayashi@21c.osakafu-u.ac.jp [NanoSquare Research Center (N2RC), Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai 599-8570 (Japan); Kurosawa, Noriyuki [Department of Basic Science, University of Tokyo, Komaba, Meguro, Tokyo 153-8902 (Japan); Arahata, Emiko [Institute of Industrial Science, University of Tokyo, Komaba, Meguro, Tokyo 153-8505 (Japan); Kato, Yusuke [Department of Basic Science, University of Tokyo, Komaba, Meguro, Tokyo 153-8902 (Japan); Tanuma, Yasunari [Faculty of Engineering and Resource Science, Akita University, Akita 010-8502 (Japan); Tanaka, Yukio [Department of Applied Physics, Nagoya University, Nagoya 464-8603 (Japan); Golubov, Alexander A. [Faculty of Science and Technology and MESA Institute for Nanotechnology, University of Twente, 7500 AE Enshede (Netherlands)

    2013-11-15

    Highlights: •We theoretically study an impurity scattering effect on the vortex core structure in a chiral p-wave superconductor. •A low-temperature vortex core shrinkage (or Kramer–Pesch effect) is investigated. •The robustness of the Kramer–Pesch effect against an impurity scattering in the Born limit is lost in the unitary limit. -- Abstract: We theoretically investigate a non-magnetic impurity effect on the temperature dependence of the vortex core shrinkage (Kramer–Pesch effect) in a chiral p-wave superconductor. The Born limit and the unitary limit scattering are compared within the framework of the quasiclassical theory of superconductivity. We find that the robustness of the Kramer–Pesch effect against the impurity scattering in the Born limit is lost in the unitary limit.

  17. Beer spoilage bacteria and hop resistance.

    Science.gov (United States)

    Sakamoto, Kanta; Konings, Wil N

    2003-12-31

    For brewing industry, beer spoilage bacteria have been problematic for centuries. They include some lactic acid bacteria such as Lactobacillus brevis, Lactobacillus lindneri and Pediococcus damnosus, and some Gram-negative bacteria such as Pectinatus cerevisiiphilus, Pectinatus frisingensis and Megasphaera cerevisiae. They can spoil beer by turbidity, acidity and the production of unfavorable smell such as diacetyl or hydrogen sulfide. For the microbiological control, many advanced biotechnological techniques such as immunoassay and polymerase chain reaction (PCR) have been applied in place of the conventional and time-consuming method of incubation on culture media. Subsequently, a method is needed to determine whether the detected bacterium is capable of growing in beer or not. In lactic acid bacteria, hop resistance is crucial for their ability to grow in beer. Hop compounds, mainly iso-alpha-acids in beer, have antibacterial activity against Gram-positive bacteria. They act as ionophores which dissipate the pH gradient across the cytoplasmic membrane and reduce the proton motive force (pmf). Consequently, the pmf-dependent nutrient uptake is hampered, resulting in cell death. The hop-resistance mechanisms in lactic acid bacteria have been investigated. HorA was found to excrete hop compounds in an ATP-dependent manner from the cell membrane to outer medium. Additionally, increased proton pumping by the membrane bound H(+)-ATPase contributes to hop resistance. To energize such ATP-dependent transporters hop-resistant cells contain larger ATP pools than hop-sensitive cells. Furthermore, a pmf-dependent hop transporter was recently presented. Understanding the hop-resistance mechanisms has enabled the development of rapid methods to discriminate beer spoilage strains from nonspoilers. The horA-PCR method has been applied for bacterial control in breweries. Also, a discrimination method was developed based on ATP pool measurement in lactobacillus cells. However

  18. Plasma, magnetic, and electromagnetic measurements at nonmagnetic bodies

    Science.gov (United States)

    Russell, C. T.; Luhmann, J. G.

    The need to explore the magnetospheres of the Earth and the giant planets is widely recognized and is an integral part of our planetary exploration program. The equal need to explore the plasma, magnetic, and electromagnetic environments of the nonmagnetic bodies is not so widely appreciated. The previous, albeit incomplete, magnetic and electric field measurements at Venus, Mars, and comets have proven critical to our understanding of their atmospheres and ionospheres in areas ranging from planetary lightning to solar wind scavenging and accretion. In the cases of Venus and Mars, the ionospheres can provide communication paths over the horizon for low-altitude probes and landers, but we know little about their lower boundaries. The expected varying magnetic fields below these planetary ionospheres penetrates the planetary crusts and can be used to sound the electrical conductivity and the thermal profiles of the interiors. However, we have no knowledge of the levels of such fields, let alone their morphology. Finally, we note that the absence of an atmosphere and an ionosphere does not make an object any less interesting for the purposes of electromagnetic exploration. Even weak remanent magnetism such as that found on the Moon during the Apollo program provides insight into the present and past states of planetary interiors. We have very intriguing data from our space probes during times of both close and distant passages of asteroids that suggest they may have coherent magnetization. If true, this observation will put important constraints on how the asteroids formed and have evolved. Our planetary exploration program must exploit its full range of exploration tools if it is to characterize the bodies of the solar system thoroughly. We should especially take advantage of those techniques that are proven and require low mass, low power, and low telemetry rates to undertake.

  19. New insights into the use of magnetic force microscopy to discriminate between magnetic and nonmagnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Neves, Cristina S; Quaresma, Pedro; Pereira, Eulalia; Eaton, Peter [Requimte/Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Baptista, Pedro V [CIGMH/Departamento de Ciencias da Vida, FCT-UNL, 2829-516 Caparica (Portugal); Carvalho, PatrIcia A [Departamento de Engenharia de Materiais, IST, Avenida Rovisco Pais 1049-100 Lisboa (Portugal); Araujo, Joao Pedro, E-mail: peter.eaton@fc.up.pt [IFIMUP, Rua do Campo Alegre, 678, 4169-007 Porto (Portugal)

    2010-07-30

    Magnetic force microscopy (MFM) is a very powerful technique, which can potentially be used to detect and localize the magnetic fields arising from nanoscopic magnetic domains, such as magnetic nanoparticles. However, in order to achieve this, we must be able to use MFM to discriminate between magnetic forces arising from the magnetic nanoparticles and nonmagnetic forces from other particles and sample features. Unfortunately, MFM can show a significant response even for nonmagnetic nanoparticles, giving rise to potentially misleading results. The literature to date lacks evidence for MFM detection of magnetic nanoparticles with nonmagnetic nanoparticles as a control. In this work, we studied magnetite particles of two sizes and with a silica shell, and compared them to nonmagnetic metallic and silica nanoparticles. We found that even on conducting, grounded substrates, significant electrostatic interaction between atomic force microscopy probes and nanoparticles can be detected, causing nonmagnetic signals that might be mistaken for a true MFM response. Nevertheless, we show that MFM can be used to discriminate between magnetic and nonmagnetic nanoparticles by using an electromagnetic shielding technique or by analysis of the phase shift data. On the basis of our experimental evidence we propose a methodology that enables MFM to be reliably used to study unknown samples containing magnetic nanoparticles, and correctly interpret the data obtained.

  20. Impurity Influence on Nitride LEDs

    Directory of Open Access Journals (Sweden)

    O.I. Rabinovich

    2014-07-01

    Full Text Available Light emitting diodes (LEDs are widely used nowadays. They are used in major parts of our life. But it is still necessary to improve their characteristics. In this paper the impurity and Indium atoms influence on the LEDs characteristics is investigated by computer simulation. Simulation was carried out in Sim Windows. The program was improved for this purpose by creating new files for AlGaInN heterostructure and devices including more than 25 basic parameters. It was found that characteristics depend on impurity and indium atoms changes a lot. The optimum impurity concentration for doping barriers between quantum wells was achieved. By varying impurity and Indium concentration the distribution in AlGaInN heterostructure LEDs characteristics could be improved.

  1. Ferromagnetism in 4H-GaN polytype doped by non-magnetic light elements Li, Be, B, C, O, F, Ne, Na, and Mg: Ab-initio study

    Energy Technology Data Exchange (ETDEWEB)

    Torrichi, M. [LPMF, Département de Physique Energétique, Faculté des Sciences, Université des Sciences et de la Technologie d’Oran Mohamed Boudiaf, Oran (Algeria); Ferhat, M. [LPMF, Département de Génie Physique, Faculté des Sciences, Université des Sciences et de la Technologie d’Oran Mohamed Boudiaf, Oran (Algeria); Bouhafs, B., E-mail: bbouhafs@gmail.com [Laboratoire de Modélisation et Simulation en Sciences des Matériaux, Université Djillali Liabès de Sidi Bel-Abbés, Sidi Bel-Abbés 22000 (Algeria)

    2016-09-15

    Using density-functional theory within the generalized-gradient approximation, we explore the magnetic behavior induced by nonmagnetic impurity X atoms, such as Li, Be, B, C, O, F, Ne, Na, and Mg on cation site in 4H-GaN polytype. The results reveal that Ne doped 4H-GaN has the highest magnetic moment of 3µ{sub B}, whereas Mg doped 4H-GaN has the lowest magnetic moment of 0.75µ{sub B}. Among the systems studied 4H-GaN doped Ne has been found to be half-metallic, whereas 4H-GaN doped F and Na are found to be nearly half-metallic. The partial density of states evidence that magnetism is achieved through a p-p like coupling between the impurity and the host 2p states. Furthermore, we inspect whether there exists a relationship between the spin-polarization and the local structure around the doping X atoms. It is found that for all the compounds studied, the total magnetic moment increases with increasing the X–N bond lengths. Interestingly, 4H-GaN:Be becomes ferromagnetic with increasing the Be–N bond length, whereas 4H-GaN:Na and 4H-GaN:F become half-metallic with increasing Na–N and F–N bond lengths. - Highlights: • The partial densities of states of 4H-GaN polytype doped light nonmagnetic elements have been investigated. • We found that 4H-GaN:Ne is half metallic. • We found that N atoms induced strong local magnetic. • We found that doping with half-filled X-s impurity states promotes ferromagnetism. • We found that doping with full-filled X-s impurity annihilates ferromagnetism.

  2. Improving the sensitivity of the hop index in patients with an ACL deficient knee by transforming the hop distance scores

    Directory of Open Access Journals (Sweden)

    Thomas Scott G

    2006-02-01

    Full Text Available Abstract Background The one leg hop for distance is one of the most commonly employed functional tests utilized in the evaluation of the ACL deficient and reconstructed patient. While the reliability of the hop test scores has been well established, validity studies have revealed low sensitivity rates in detecting functional limitations using the hop index (the ratio or percentage of limb performance. However, the impact of the inherent limitations associated with the hop index have not been investigated to date. One specific limitation relates to the impact of the differences in the underlying hop distance scores. Therefore, this pilot study set out to determine: 1 the impact that between limb differences in hop distance has on the sensitivity of the hop index in detecting functional limitations and; 2 whether a logarithmic transformation of the underlying hop distance scores improves the sensitivity of the hop index. Methods A cross sectional design involving the evaluation of one leg hop for distance performance in a consecutive sample of 10 ACL deficient males with an isolated ACL tear awaiting reconstructive surgery and nine gender, age-matched controls. Results In the ACL deficient, the hop index was associated with the distance hopped on the non-injured limb (r = -0.66, p = 0.04 but not on the injured limb. Transformation (logarithmic of the hop distance scores and re-calculation of the hop index using the transformed scores increased the sensitivity of the hop index in the detection of functional limitations from 20 to 60% and 50 to 70% using the normal limb symmetry reference norms of ≥ 85% and 90% respectively. Conclusion The distance hopped on the non-injured limb is a critical factor in detecting functional limitations using the hop index in patients with an ACL deficient knee. Logarithmic transformation of the hop distance scores minimizes the effect of the arithmetic differences between limbs however; the sensitivity of the hop

  3. Dynamic molecular graphs: "hopping" structures.

    Science.gov (United States)

    Cortés-Guzmán, Fernando; Rocha-Rinza, Tomas; Guevara-Vela, José Manuel; Cuevas, Gabriel; Gómez, Rosa María

    2014-05-05

    This work aims to contribute to the discussion about the suitability of bond paths and bond-critical points as indicators of chemical bonding defined within the theoretical framework of the quantum theory of atoms in molecules. For this purpose, we consider the temporal evolution of the molecular structure of [Fe{C(CH2 )3 }(CO)3 ] throughout Born-Oppenheimer molecular dynamics (BOMD), which illustrates the changing behaviour of the molecular graph (MG) of an electronic system. Several MGs with significant lifespans are observed across the BOMD simulations. The bond paths between the trimethylenemethane and the metallic core are uninterruptedly formed and broken. This situation is reminiscent of a "hopping" ligand over the iron atom. The molecular graph wherein the bonding between trimethylenemethane and the iron atom takes place only by means of the tertiary carbon atom has the longest lifespan of all the considered structures, which is consistent with the MG found by X-ray diffraction experiments and quantum chemical calculations. In contrast, the η(4) complex predicted by molecular-orbital theory has an extremely brief lifetime. The lifespan of different molecular structures is related to bond descriptors on the basis of the topology of the electron density such as the ellipticities at the FeCH2 bond-critical points and electron delocalisation indices. This work also proposes the concept of a dynamic molecular graph composed of the different structures found throughout the BOMD trajectories in analogy to a resonance hybrid of Lewis structures. It is our hope that the notion of dynamic molecular graphs will prove useful in the discussion of electronic systems, in particular for those in which analysis on the basis of static structures leads to controversial conclusions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Analysis of the experimental data for impurity-band conduction in Mn-doped InSb

    Energy Technology Data Exchange (ETDEWEB)

    Kajikawa, Yasutomo [Department of Electric and Control Systems Engineering, Interdisciplinary Faculty of Science and Engineering, Shimane University, Matsue (Japan)

    2017-01-15

    The experimental data of the temperature-dependent Hall-effect measurements on Mn-doped p -type InSb samples, which exhibit the anomalous sign reversal of the Hall coefficient to negative at low temperatures, have been analyzed on the basis of the nearest-neighbor hopping model in an impurity band. It is shown that the anomalous sign reversal of the Hall coefficient to negative can be well explained with assuming the hopping Hall factor in the form of A{sub hop} = (k{sub B}T/J{sub 3}) exp(K{sub NNH}T{sub 3}/T) with the negative sign of J{sub 3}. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Impurity bubbles in a BEC

    Science.gov (United States)

    Timmermans, Eddy; Blinova, Alina; Boshier, Malcolm

    2013-05-01

    Polarons (particles that interact with the self-consistent deformation of the host medium that contains them) self-localize when strongly coupled. Dilute Bose-Einstein condensates (BECs) doped with neutral distinguishable atoms (impurities) and armed with a Feshbach-tuned impurity-boson interaction provide a unique laboratory to study self-localized polarons. In nature, self-localized polarons come in two flavors that exhibit qualitatively different behavior: In lattice systems, the deformation is slight and the particle is accompanied by a cloud of collective excitations as in the case of the Landau-Pekar polarons of electrons in a dielectric lattice. In natural fluids and gases, the strongly coupled particle radically alters the medium, e.g. by expelling the host medium as in the case of the electron bubbles in superfluid helium. We show that BEC-impurities can self-localize in a bubble, as well as in a Landau-Pekar polaron state. The BEC-impurity system is fully characterized by only two dimensionless coupling constants. In the corresponding phase diagram the bubble and Landau-Pekar polaron limits correspond to large islands separated by a cross-over region. The same BEC-impurity species can be adiabatically Feshbach steered from the Landau-Pekar to the bubble regime. This work was funded by the Los Alamos LDRD program.

  6. Landau-Zener type surface hopping algorithms

    CERN Document Server

    Belyaev, Andrey K; Trigila, Giulio

    2014-01-01

    A class of surface hopping algorithms is studied comparing two recent Landau-Zener (LZ) formulas for the probability of nonadiabatic transitions. One of the formulas requires a diabatic representation of the potential matrix while the other one depends only on the adiabatic potential energy surfaces. For each classical trajectory, the nonadiabatic transitions take place only when the surface gap attains a local minimum. Numerical experiments are performed with deterministically branching trajectories and with probabilistic surface hopping. The deterministic and the probabilistic approach confirm the good agreement of both the LZ probabilities as well the good approximation of the reference solution computed solving the Schroedinger equation via a grid based pseudo-spectral method. Visualizations of position expectations and superimposed surface hopping trajectories with reference position densities illustrate the effective dynamics of the investigated algorithms.

  7. Hopping models for ion conduction in noncrystals

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Schrøder, Thomas

    2007-01-01

    Ion conduction in noncrystals (glasses, polymers, etc) has a number of properties in common. In fact, from a purely phenomenological point of view, these properties are even more widely observed: ion conduction behaves much like electronic conduction in disordered materials (e.g., amorphous...... semiconductors). These universalities are subject of much current interest, for instance interpreted in the context of simple hopping models. In the present paper we first discuss the temperature dependence of the dc conductivity in hopping models and the importance of the percolation phenomenon. Next......, the experimental (quasi)universality of the ac conductivity is discussed. It is shown that hopping models are able to reproduce the experimental finding that the response obeys time-temperature superposition, while at the same time a broad range of activation energies is involved in the conduction process. Again...

  8. Solution to the sign problem in a frustrated quantum impurity model

    CERN Document Server

    Hann, Connor T; Chandrasekharan, Shailesh

    2016-01-01

    In this work we solve the sign problem of a frustrated quantum impurity model consisting of three quantum spin-half chains interacting through an anti-ferromagnetic Heisenberg interaction at one end. We first map the model into a repulsive Hubbard model of spin-half fermions hopping on three independent one dimensional chains that interact through a triangular hopping at one end. We then convert the fermion model into an inhomogeneous one dimensional model and express the partition function as a weighted sum over fermion worldline configurations. By imposing a pairing of fermion worldlines in half the space we show that all negative weight configurations can be eliminated. This pairing naturally leads to the original frustrated quantum spin model at half filling and thus solves its sign problem.

  9. Improvement of microwave magnetic properties by inserting nonmagnetic layer

    Science.gov (United States)

    Li, Xiaoting; An, Chao; Wang, Zhen; Xu, Chunlong; Shi, Gang; Wang, Jinguo; Hou, Zhaoyang; Xi, Li

    2017-01-01

    Co/NM (nonmagnetic Ag and SiO2)/Co sandwich structure films with different thicknesses of NM were fabricated on Si(111) substrate via oblique radio frequency sputtering. With increasing thickness of nonmagnetic Ag (tAg), in-plane magnetic anisotropy field Hk initially increased from 100 Oe of tAg = 0 nm to 220 Oe of tAg = 1.5 nm, and then decreased when tAg > 1.5 nm. Resonance frequency showed the same tendency with maximum 5.2 GHz when tAg = 1.5 nm. Damp factor increased from 0.02 for tAg = 0-0.08 for tAg = 2.0 nm. The same result was observed in inserting oxide nonmagnetic SiO2 layer. This can be attributed to the competition between interface energy and exchange coupling energy.

  10. Magnetofluidic concentration and separation of non-magnetic particles using two magnet arrays.

    Science.gov (United States)

    Hejazian, Majid; Nguyen, Nam-Trung

    2016-07-01

    The present paper reports the use of diluted ferrofluid and two arrays of permanent magnets for the size-selective concentration of non-magnetic particles. The micro magnetofluidic device consists of a straight channels sandwiched between two arrays of permanent magnets. The permanent magnets create multiple capture zones with minimum magnetic field strength along the channel. The complex interaction between magnetic forces and hydrodynamic force allows the device to operate in different regimes suitable for concentration of non-magnetic particles with small difference in size. Our experimental results show that non-magnetic particles with diameters of 3.1 μm and 4.8 μm can be discriminated and separated with this method. The results from this study could be used as a guide for the design of size-sensitive separation devices for particle and cell based on negative magnetophoresis.

  11. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of α-iron containing nonmagnetic particles

    Directory of Open Access Journals (Sweden)

    Yi Li

    2015-07-01

    Full Text Available The magnetic hysteresis loops and Barkhausen noise of a single α-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.

  12. Simulation of magnetic hysteresis loops and magnetic Barkhausen noise of α-iron containing nonmagnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi; Li, Qiulin; Liu, Wei, E-mail: liuw@mail.tsinghua.edu.cn [School of Material Science and Engineering, Tsinghua University, Beijing, 100084 (China); Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055 (China); Xu, Ben [School of Material Science and Engineering, Tsinghua University, Beijing, 100084 (China); Hu, Shenyang; Li, Yulan [Energy Materials Division, Pacific Northwest National Laboratory, Richland, WA, 99352 (United States)

    2015-07-15

    The magnetic hysteresis loops and Barkhausen noise of a single α-iron with nonmagnetic particles are simulated to investigate into the magnetic hardening due to Cu-rich precipitates in irradiated reactor pressure vessel (RPV) steels. Phase field method basing Landau-Lifshitz-Gilbert (LLG) equation is used for this simulation. The results show that the presence of the nonmagnetic particle could result in magnetic hardening by making the nucleation of reversed domains difficult. The coercive field is found to increase, while the intensity of Barkhausen noise voltage is decreased when the nonmagnetic particle is introduced. Simulations demonstrate the impact of nucleation field of reversed domains on the magnetization reversal behavior and the magnetic properties.

  13. Removal of a giant nonmagnetic intraocular foreign body using micro alligator forceps.

    Science.gov (United States)

    Liang, Shenzhi; Wan, Guangming; Li, Xiujuan; Liu, Xiaoqiang; Zhu, Yu

    2014-01-01

    To introduce a new method for removal of a giant nonmagnetic intraocular foreign body using micro alligator forceps. Eleven patients underwent pars plana vitrectomy and lensectomy. The micro alligator forceps were used to grasp and extract the giant nonmagnetic intraocular foreign body through a sclerocorneal tunnel. All patients underwent surgical removal of the intraocular foreign body successfully without any intraoperative complications. The alligator forceps were operational in the intraocular environment and effective in surgical maneuvers. There was no accidental slippage during the procedures. Micro alligator forceps are a feasible option for removal of giant nonmagnetic intraocular foreign body during vitreoretinal surgery and offer advances in terms of operating stability and surgical safety. Copyright 2014, SLACK Incorporated.

  14. Development of a Non-Magnetic Inertial Sensor for Vibration Stabilization in a Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Frisch, Josef; Decker, Valentin; Doyle, Eric; Hendrickson, Linda; Himel, Thomas; Markiewicz, Thomas; Seryi, Andrei; /SLAC; Chang, Allison; Partridge, Richard; /Brown U.

    2006-09-01

    One of the options for controlling vibration of the final focus magnets in a linear collider is to use active feedback based on accelerometers. While commercial geophysics sensors have noise performance that substantially exceeds the requirements for a linear collider, they are physically large, and cannot operate in the strong magnetic field of the detector. Conventional nonmagnetic sensors have excessive noise for this application. We report on the development of a non-magnetic inertial sensor, and on a novel commercial sensor both of which have demonstrated the required noise levels for this application.

  15. Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials

    Energy Technology Data Exchange (ETDEWEB)

    Yu Zhenzhong; Feng Yijun; Xu Xiaofei; Zhao Junming; Jiang Tian, E-mail: yjfeng@nju.edu.cn [Department of Electronic Engineering, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China)

    2011-05-11

    We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.

  16. Magnetization Reversal Process of Single Crystal α-Fe Containing a Nonmagnetic Particle

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi [Tsinghua Univ., Beijing (China); Tsinghua Univ., Shenzhen (China); Xu, Ben [Tsinghua Univ., Beijing (China); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Yulan [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Qiu-Lin [Tsinghua Univ., Beijing (China); Tsinghua Univ., Shenzhen (China); Liu, Wei [Tsinghua Univ., Beijing (China); Tsinghua Univ., Shenzhen (China)

    2015-09-25

    The magnetization reversal process and hysteresis loops in a single crystal α-iron with nonmagnetic particles are simulated in this work based on the Landau-Lifshitz–Gilbert equation. The evolutions of the magnetic domain morphology are studied, and our analyses show that the magnetization reversal process is affected by the interaction between the moving domain wall and the existing nonmagnetic particles. This interaction strongly depends on the size of the particles, and it is found that particles with a particular size contribute the most to magnetic hardening.

  17. HPLC Analysis of [Alpha]- and [Beta]-Acids in Hops

    Science.gov (United States)

    Danenhower, Travis M.; Force, Leyna J.; Petersen, Kenneth J.; Betts, Thomas A.; Baker, Gary A.

    2008-01-01

    Hops have been used for centuries to impart aroma and bitterness to beer. The cones of the female hop plant contain both essential oils, which include many of the fragrant components of hops, and a collection of compounds known as [alpha]- and [beta]-acids that are the precursors to bittering agents. In order for brewers to predict the ultimate…

  18. Revolutionizing Environmental Education through Indigenous Hip Hop Culture

    Science.gov (United States)

    Gorlewski, Julie; Porfilio, Brad J.

    2012-01-01

    Based upon the life histories of six Indigenous hip hop artists of the Beat Nation artist collective, this essay captures how Indigenous hip hop has the potential to revolutionize environmental education. Hip hop provides Indigenous youth an emancipatory space to raise their opposition to neocolonial controls of Indigenous territories that…

  19. Revolutionizing Environmental Education through Indigenous Hip Hop Culture

    Science.gov (United States)

    Gorlewski, Julie; Porfilio, Brad J.

    2012-01-01

    Based upon the life histories of six Indigenous hip hop artists of the Beat Nation artist collective, this essay captures how Indigenous hip hop has the potential to revolutionize environmental education. Hip hop provides Indigenous youth an emancipatory space to raise their opposition to neocolonial controls of Indigenous territories that…

  20. HPLC Analysis of [Alpha]- and [Beta]-Acids in Hops

    Science.gov (United States)

    Danenhower, Travis M.; Force, Leyna J.; Petersen, Kenneth J.; Betts, Thomas A.; Baker, Gary A.

    2008-01-01

    Hops have been used for centuries to impart aroma and bitterness to beer. The cones of the female hop plant contain both essential oils, which include many of the fragrant components of hops, and a collection of compounds known as [alpha]- and [beta]-acids that are the precursors to bittering agents. In order for brewers to predict the ultimate…

  1. Abnormal hopping conduction in semiconducting polycrystalline graphene

    Science.gov (United States)

    Park, Jeongho; Mitchel, William C.; Elhamri, Said; Grazulis, Larry; Altfeder, Igor

    2013-07-01

    We report the observation of an abnormal carrier transport phenomenon in polycrystalline semiconducting graphene grown by solid carbon source molecular beam epitaxy. At the lowest temperatures in samples with small grain size, the conduction does not obey the two-dimensional Mott-type variable-range hopping (VRH) conduction often reported in semiconducting graphene. The hopping exponent p is found to deviate from the 1/3 value expected for Mott VRH with several samples exhibiting a p=2/5 dependence. We also show that the maximum energy difference between hopping sites is larger than the activation energy for nearest-neighbor hopping, violating the assumptions of the Mott model. The 2/5 dependence more closely agrees with the quasi-one-dimensional VRH model proposed by Fogler, Teber, and Shklovskii (FTS). In the FTS model, conduction occurs by tunneling between neighboring metallic wires. We suggest that metallic edge states and conductive grain boundaries play the role of the metallic wires in the FTS model.

  2. Uudised : Ooper. Hip-hop. Madonna

    Index Scriptorium Estoniae

    2005-01-01

    Rumeenia sopran Nelly Miricioiu Vincenzo Bellini ooperi "Norma" nimiosas Nederlandse Operas Amsaterdamis 7.-28. märtsini. 4. märtsil Tallinna klubis Hollywood üritusel "Hip-Hop Café" New Yorgi duo Camp Lo. Ameerika poplaulja Madonna võttis vastu filmirolli

  3. The Philippine "Hip Hop Stick Dance"

    Science.gov (United States)

    Lewis, Lisa

    2012-01-01

    This article introduces a dance that blends the traditional cultural heritage of the Philippines with modern music and moves. "Hip Hop Stick Dance" incorporates Tinikling (the Philippine national dance) and Arnis (a Filipino style of martial arts) to create a contemporary combination of rhythm, dance, and fitness. It was designed to introduce…

  4. Forecasting and management of hop downy mildew

    Science.gov (United States)

    Downy mildew of hop, caused by Pseudoperonospora humuli, is managed in the Pacific Northwestern U.S. by regular application of fungicides. A degree-day model that forecasts the first emergence of shoots systemically infection with P. humuli (termed basal spikes) and a risk index for secondary sprea...

  5. Uudised : Ooper. Hip-hop. Madonna

    Index Scriptorium Estoniae

    2005-01-01

    Rumeenia sopran Nelly Miricioiu Vincenzo Bellini ooperi "Norma" nimiosas Nederlandse Operas Amsaterdamis 7.-28. märtsini. 4. märtsil Tallinna klubis Hollywood üritusel "Hip-Hop Café" New Yorgi duo Camp Lo. Ameerika poplaulja Madonna võttis vastu filmirolli

  6. The Philippine "Hip Hop Stick Dance"

    Science.gov (United States)

    Lewis, Lisa

    2012-01-01

    This article introduces a dance that blends the traditional cultural heritage of the Philippines with modern music and moves. "Hip Hop Stick Dance" incorporates Tinikling (the Philippine national dance) and Arnis (a Filipino style of martial arts) to create a contemporary combination of rhythm, dance, and fitness. It was designed to introduce…

  7. Impurity doping processes in silicon

    CERN Document Server

    Wang, FFY

    1981-01-01

    This book introduces to non-experts several important processes of impurity doping in silicon and goes on to discuss the methods of determination of the concentration of dopants in silicon. The conventional method used is the discussion process, but, since it has been sufficiently covered in many texts, this work describes the double-diffusion method.

  8. Featherless Dinosaurs and the Hip-Hop Simulacrum: Reconsidering Hip-Hop's Appropriateness for the Music Classroom

    Science.gov (United States)

    Kruse, Adam J.

    2016-01-01

    This article offers considerations for music teachers interested in including hip-hop music in their classrooms but who might feel concerned with or overwhelmed by issues of appropriateness. Two concerns related to hip-hop music are examined: language and negative social themes. Commercial interests in hip-hop music have created a simulacrum (or…

  9. Breatherlike impurity modes in discrete nonlinear lattices

    DEFF Research Database (Denmark)

    Hennig, D.; Rasmussen, Kim; Tsironis, G. P.

    1995-01-01

    We investigate the properties of a disordered generalized discrete nonlinear Schrodinger equation, containing both diagonal and nondiagonal nonlinear terms. The equation models a Linear host lattice doped with nonlinear impurities. We find different types of impurity states that form itinerant...

  10. Hop-by-hop Content Distribution with Network Coding in Multihop Wireless Networks

    Directory of Open Access Journals (Sweden)

    Rami Halloush

    2017-02-01

    Full Text Available The predominant use of today's networks is content access and distribution. Network Coding (NC is an innovative technique that has potential to improve the efficiency of multicast content distribution over multihop Wireless Mesh Networks (WMNs by allowing intermediate Forwarding Nodes (FNs to encode and then forward data packets. Practical protocols are needed to realize the benefits of the NC technique. However, the existing NC-based multicast protocols cannot accurately determine the minimum number of coded packets that a FN should send in order to ensure successful data delivery to the destinations, so that many redundant packets are injected into the network, leading to performance degradation. In this paper, we propose HopCaster, a novel reliable multicast protocol that incorporates network coding with hop-by-hop transport. HopCaster completely eliminates the need for estimating the number of coded packets to be transmitted by a FN, and avoids redundant packet transmissions. It also effectively addresses the challenges of heterogeneous multicast receivers. Moreover, a cross-layer multicast rate adaptation mechanism is proposed, which enables HopCaster to optimize multicast throughput by dynamically adjusting wireless transmission rate based on the changes in the receiver population and channel conditions during the course of multicasting a coded data chunk. Our evaluations show that HopCaster significantly outperforms the existing NC-based multicast protocols.

  11. FLAPW-GGA calculations of the influence of Mn, Fe, and Co impurities on the electronic and magnetic properties of layered oxychalcogenides LaCuSO and LaCuSeO

    Science.gov (United States)

    Bannikov, V. V.; Ivanovskii, A. L.

    2012-06-01

    The electronic and magnetic properties of oxychalcogenides LaCuSO and LaCuSeO with a layered ZrCuSiAs-type structure doped with impurity atoms M = Mn, Fe, and Co have been predicted using the first-principles FLAPW-GGA method. It has been shown that a partial substitution of 3 d n < 9 metal atoms for copper atoms in the structure of the initial matrix leads to the transition of the oxychalcogenides (nonmagnetic semiconductors) to the state of a magnetic half-metal with 100% spin polarization of near-Fermi electrons. In this case, the magnetic and conducting properties of the LaCu1 - x M x S(Se)O systems are determined by the states of the [Cu2(S,Se)2] blocks with magnetic impurities separated by nonmagnetic semiconducting [La2O2] blocks.

  12. Dynamics of impurity attraction and repulsion of an intrinsic localized mode in a driven 1-D cantilever array

    CERN Document Server

    Sato, M; Shi, W; Shige, S; Ishikawa, T; Soga, Y; Hubbard, B E; Ilic, B; Sievers, A J

    2014-01-01

    Both low frequency and high frequency impurity modes have been produced in a SiN micromechanical cantilever array by illumination with either an infrared or visible laser. When such laser-induced impurities are placed near a driven intrinsic localized mode (ILM) it is either repelled or attracted. By measuring the linear response spectrum for these two cases it was found that vibrational hopping of the ILM takes place when the natural frequency of the ILM and an even symmetry linear local mode are symmetrically located about the driven ILM frequency so that parametric excitation of these two linear modes is enhanced, amplifying the lateral motion of the ILM. Numerical simulations are consistent with these signature findings. It is also demonstrated that the correct sign of the observed interaction can be found with a harmonic lattice-impurity model but the magnitude of the effect is enhanced in a nonlinear lattice.

  13. Fundamental aspects of metallic impurities and impurity interactions in silicon during device processing

    Energy Technology Data Exchange (ETDEWEB)

    Graff, K. [TEMIC, TELEFUNKEN, Heilbronn (Germany)

    1995-08-01

    A review on the behavior of metallic impurities in silicon can be considerably simplified by a restriction on pure, dislocation-free, monocrystalline silicon. In this case interactions between different impurities and between impurities and grown-in lattice defects can be reduced. This restriction is observed in Chapter 1 for discussing the general behavior of metallic impurities in silicon.

  14. Leg stiffness primarily depends on ankle stiffness during human hopping.

    Science.gov (United States)

    Farley, C T; Morgenroth, D C

    1999-03-01

    When humans hop in place or run forward, they adjust leg stiffness to accommodate changes in stride frequency or surface stiffness. The goal of the present study was to determine the mechanisms by which humans adjust leg stiffness during hopping in place. Five subjects hopped in place at 2.2 Hz while we collected force platform and kinematic data. Each subject completed trials in which they hopped to whatever height they chose ("preferred height hopping") and trials in which they hopped as high as possible ("maximum height hopping"). Leg stiffness was approximately twice as great for maximum height hopping as for preferred height hopping. Ankle torsional stiffness was 1.9-times greater while knee torsional stiffness was 1.7-times greater in maximum height hopping than in preferred height hopping. We used a computer simulation to examine the sensitivity of leg stiffness to the observed changes in ankle and knee stiffness. Our model consisted of four segments (foot, shank, thigh, head-arms-trunk) interconnected by three torsional springs (ankle, knee, hip). In the model, increasing ankle stiffness by 1.9-fold, as observed in the subjects, caused leg stiffness to increase by 2.0-fold. Increasing knee stiffness by 1.7-fold had virtually no effect on leg stiffness. Thus, we conclude that the primary mechanism for leg stiffness adjustment is the adjustment of ankle stiffness.

  15. Non-magnetic negative-refraction systems for terahertz and far-infrared frequencies

    CERN Document Server

    Alekseyev, Leonid V; Narimanov, Evgenii E

    2012-01-01

    We demonstrate that homogeneous naturally-occurring materials can form non-magnetic negative refractive index systems, and present specific realizations of the proposed approach for the THz and far-IR frequencies. The proposed structure operates away from resonance, thereby promising the capacity for low-loss devices.

  16. Nurse Outcomes in Magnet® and Non-Magnet Hospitals

    Science.gov (United States)

    Kelly, Lesly A.; McHugh, Matthew D.; Aiken, Linda H.

    2017-01-01

    The important goals of Magnet® hospitals are to create supportive professional nursing care environments. A recently published paper found little difference in work environments between Magnet and non-Magnet hospitals. The aim of this study was to determine whether work environments, staffing, and nurse outcomes differ between Magnet and non-Magnet hospitals. A secondary analysis of data from a 4-state survey of 26,276 nurses in 567 acute care hospitals to evaluate differences in work environments and nurse outcomes in Magnet and non-Magnet hospitals was conducted. Magnet hospitals had significantly better work environments (t = −5.29, P < .001) and more highly educated nurses (t = −2.27, P < .001). Magnet hospital nurses were 18% less likely to be dissatisfied with their job (P < .05) and 13% less likely to report high burnout (P < .05). Magnet hospitals have significantly better work environments than non-Magnet hospitals. The better work environments of Magnet hospitals are associated with lower levels of nurse job dissatisfaction and burnout. PMID:22976894

  17. Magnetism induced by nonmagnetic dopants in zinc-blende SiC: First-principle calculations

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Magnetism induced by the nonmagnetic dopants in the zinc-blende SiC (3C-SiC) is investigated by first-principle calculations. The atoms of the first 20 elements in the periodic table except inert gas are used to replace either Si or C atoms as dopants. We find that some nonmagnetic substitutional dopants (mainly the Group IA, Group IIA, Group IIIB, and Group VIIB elements) prefer the spin-polarized ground states with local magnetic moments. In general, the condition for obtaining the local magnetic moments and the magnetic ground state requires that the dopants are p-type and have large electronegativity difference from the neighboring host atoms. The magnetic moments can be tuned over a range between 1 μ B and 3 μ B by doping with the nonmagnetic elements. The nearest-neighbor exchange couplings J 0 between the local magnetic moments are quite large and the codoping method is proposed to increase the dopant concentration. These imply that the nonmagnetic doping in SiC may exhibit collective magnetism. Moreover, the Group IIA Mg and Ca atoms substituting the preferred Si atoms favor the ferromagnetic ground states with the half-metallic electronic properties, which suggests that Mg or Ca substitutional doping on the Si sites in SiC could be a potential route to fabricating the diluted magnetic semiconductors.

  18. Pulsed remote field eddy current technique applied to non-magnetic flat conductive plates

    Science.gov (United States)

    Yang, Binfeng; Zhang, Hui; Zhang, Chao; Zhang, Zhanbin

    2013-12-01

    Non-magnetic metal plates are widely used in aviation and industrial applications. The detection of cracks in thick plate structures, such as multilayered structures of aircraft fuselage, has been challenging in nondestructive evaluation societies. The remote field eddy current (RFEC) technique has shown advantages of deep penetration and high sensitivity to deeply buried anomalies. However, the RFEC technique is mainly used to evaluate ferromagnetic tubes. There are many problems that should be fixed before the expansion and application of this technique for the inspection of non-magnetic conductive plates. In this article, the pulsed remote field eddy current (PRFEC) technique for the detection of defects in non-magnetic conducting plates was investigated. First, the principle of the PRFEC technique was analysed, followed by the analysis of the differences between the detection of defects in ferromagnetic and non-magnetic plain structures. Three different models of the PRFEC probe were simulated using ANSYS. The location of the transition zone, defect detection sensitivity and the ability to detect defects in thick plates using three probes were analysed and compared. The simulation results showed that the probe with a ferrite core had the highest detecting ability. The conclusions derived from the simulation study were also validated by conducting experiments.

  19. Magnetic field aligned assembly of nonmagnetic composite dumbbells in nanoparticle-based aqueous ferrofluid.

    Science.gov (United States)

    Takahashi, Hayato; Nagao, Daisuke; Watanabe, Kanako; Ishii, Haruyuki; Konno, Mikio

    2015-05-26

    Monodisperse, nonmagnetic, asymmetrical composite dumbbells in a suspension of magnetic nanoparticles (ferrofluid) were aligned by application of an external magnetic field to the ferrofluid. The asymmetrical composite dumbbells were prepared by two-step soap-free emulsion polymerization consisting of the first polymerization to coat spherical silica cores with cross-linked poly(methyl methacrylate) (PMMA) shell and the second polymerization to protrude a polystyrene (PSt) lobe from the core-shell particles. A chain structure of nonmagnetic dumbbells oriented to the applied magnetic field was observed at nanoparticle content of 2.0 vol % and field strengths higher than 1.0 mT. A similar chain structure of the dumbbells was observed under application of alternating electric field at strengths higher than 50 V/mm. Parallel and orthogonally combined applications of the electric and magnetic fields were also conducted to examine independence of the electric and magnetic applications as operational factors in the dumbbell assembling. Dumbbell chains stiffer than those in a single application of external field were formed in the parallel combined application of electric and magnetic fields. The orthogonal combination of the different applied fields could form a magnetically aligned chain structure of the nonmagnetic dumbbells oriented to the electric field. The present work experimentally indicated that the employment of inverse magnetorheological effect for nonmagnetic, anisotropic particles can be a useful method for the simultaneous controls over the orientation and the positon of anisotropic particles in their assembling.

  20. On a general class of quadratic hopping sequences

    Institute of Scientific and Technical Information of China (English)

    JIA HuaDing; YUAN Ding; PENG DaiYuan; GUO Ling

    2008-01-01

    Based upon quadratic polynomials over the finite field, a new class of frequency hopping sequences with large family size suitable for applications in time/frequency hopping CDMA systems, multi-user radar and sonar systems is proposed and investigated. It is shown that the new time/frequency hopping sequences have at most one hit in their autocorrelation functions and at most two hits in their crosscorrelation functions except for a special case, and their family size is much larger than the conventional quadratic hopping sequences. The percentage of full collisions for the new quadratic hopping sequences is discussed. In addition, the average number of hits for the new quadratic hopping sequences, quadratic congruence sequences, extended quadratic congruence sequences and the general linear hopping sequences are also derived.

  1. Phase diagram of hopping conduction mechanisms in polymer nanofiber network

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jeng-Ting; Lu, Yu-Cheng; Jiang, Shiau-Bin; Zhong, Yuan-Liang, E-mail: ylzhong@cycu.edu.tw [Department of Physics and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China); Yeh, Jui-Ming [Department of Chemistry and Center for Nanotechnology, Chung Yuan Christian University, Chung-Li 32023, Taiwan (China)

    2015-12-07

    Network formation by nanofiber crosslinking is usually in polymer materials as application in organic semiconductor devices. Electron hopping transport mechanisms depend on polymer morphology in network. Conducting polymers morphology in a random network structure is modeled by a quasi-one-dimensional system coupled of chains or fibers. We observe the varying hopping conduction mechanisms in the polyaniline nanofibers of the random network structure. The average diameter d of the nanofibers is varied from approximately 10 to 100 nm. The different dominant hopping mechanisms including Efros-Shklovskii variable-range hopping (VRH), Mott VRH, and nearest-neighbor hopping are dependent on temperature range and d in crossover changes. The result of this study is first presented in a phase diagram of hopping conduction mechanisms based on the theories of the random network model. The hopping conduction mechanism is unlike in normal semiconductor materials.

  2. Spin Hall conductivity in the impure two-dimensional Rashba s-wave superconductor

    Science.gov (United States)

    Biderang, M.; Yavari, H.

    2016-06-01

    Based on the Kubo formula approach, the spin Hall conductivity (SHC) of a two-dimensional (2D) Rashba s-wave superconductor in the presence of nonmagnetic impurities is calculated. We will show that by increasing the superconducting gap, the SHC decreases monotonically to zero, while by decreasing the concentration of impurities at zero gap, the SHC closes to the clean limit universal value - e/8 π. As a function of the impurity relaxation rate τ at Tc = 0.1 and γ = 0.01 (γ is the spin-orbit coupling in unit of eV · m), we will show that in the dirty limit (τ → 0) the SHC vanishes, and by increasing the relaxation time (τ → ∞) the SHC depends on the value of superconducting gap (Δ = 1.76Tc√{ 1 -T/Tc }), is changed from zero for full gap to -e/8 π in zero gap. At low temperatures, the SHC goes to zero exponentially and near the critical temperature depending on the concentration of the scattering centers, the SHC will tend to the value of normal state. We will also show that the SHC is independent of spin-orbit coupling (γ) in the clean limit.

  3. Uudised : Pop-karneval. Hip-hop

    Index Scriptorium Estoniae

    2005-01-01

    Muusika- ja kunstikarnevalist "Beta Bubble" 1. apr. Tallinnas Von Krahlis. Pärnu taasühinenud hip-hop-bänd Noizmakaz (TommyBoy ja Alko) sõlmis lepingu plaadifirmaga Mindnote ja annab selle alt apr. keskel välja oma teise albumi "Valitud mõtted".1. apr. tuleb müügile Noizmakazi singel "Miski muu ei loe", debüüt "Social Poetry" ilmus aastal 2001

  4. Collision-based mechanics of bipedal hopping

    OpenAIRE

    Gutmann, Anne K.; Lee, David V; McGowan, Craig P.

    2013-01-01

    The muscle work required to sustain steady-speed locomotion depends largely upon the mechanical energy needed to redirect the centre of mass and the degree to which this energy can be stored and returned elastically. Previous studies have found that large bipedal hoppers can elastically store and return a large fraction of the energy required to hop, whereas small bipedal hoppers can only elastically store and return a relatively small fraction. Here, we consider the extent to which large and...

  5. Uudised : Pop-karneval. Hip-hop

    Index Scriptorium Estoniae

    2005-01-01

    Muusika- ja kunstikarnevalist "Beta Bubble" 1. apr. Tallinnas Von Krahlis. Pärnu taasühinenud hip-hop-bänd Noizmakaz (TommyBoy ja Alko) sõlmis lepingu plaadifirmaga Mindnote ja annab selle alt apr. keskel välja oma teise albumi "Valitud mõtted".1. apr. tuleb müügile Noizmakazi singel "Miski muu ei loe", debüüt "Social Poetry" ilmus aastal 2001

  6. Exploiting Multi-user Diversity and Multi-hop Diversity in Dual-hop Broadcast Channels

    KAUST Repository

    Zafar, Ammar

    2013-05-21

    We propose joint user-and-hop scheduling over dual-hop block-fading broadcast channels in order to exploit multi-user diversity gains and multi-hop diversity gains all together. To achieve this objective, the first and second hops are scheduled opportunistically based on the channel state information. The joint scheduling problem is formulated as maximizing the weighted sum of the long term achievable rates of the users under a stability constraint, which means that in the long term the rate received by the relay should equal the rate transmitted by it, in addition to power constraints. We show that this problem is equivalent to a single-hop broadcast channel by treating the source as a virtual user with an optimal weight that maintains the stability constraint. We show how to obtain the source weight either off-line based on channel statistics or on real-time based on channel measurements. Furthermore, we consider special cases including the maximum sum-rate scheduler and the proportional fair scheduler. We also show how to extend the scheme into one that allows multiple user scheduling via superposition coding with successive decoding. Numerical results demonstrate that our proposed joint scheduling scheme enlarges the rate region as compared to scheduling schemes that exploit the diversity gains partially.

  7. Impurity-induced divertor plasma oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, R. D., E-mail: rsmirnov@ucsd.edu; Krasheninnikov, S. I.; Pigarov, A. Yu. [University of California, San Diego, La Jolla, California 92093 (United States); Kukushkin, A. S. [NRC “Kurchatov Institute”, Moscow 123182 (Russian Federation); National Research Nuclear University MEPhI, Moscow 115409 (Russian Federation); Rognlien, T. D. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2016-01-15

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ion transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. The implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.

  8. Impurity-induced divertor plasma oscillations

    Science.gov (United States)

    Smirnov, R. D.; Kukushkin, A. S.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2016-01-01

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ion transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. The implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.

  9. Rethinking Pedagogy in Urban Spaces: Implementing Hip-Hop Pedagogy in the Urban Science Classroom

    Science.gov (United States)

    Adjapong, Edmund S.; Emdin, Christopher

    2015-01-01

    A significant amount of research regarding Hip-Hop Based Education (HHBE) fails to provide insight on how to incorporate elements of Hip-Hop into daily teaching practices; rather Hip-Hop based educators focus mainly on incorporating Hip-Hop culture into curricula. This study explores the benefits of using two specific Hip-Hop pedagogical practices…

  10. Bounds on the hop domination number of a tree

    Indian Academy of Sciences (India)

    S K Ayyaswamy; B Krishnakumari; C Natarajan; Y B Venkatakrishnan

    2015-11-01

    A hop dominating set of a graph is a set of vertices of if for every vertex of () \\ D, there exists $u \\in D$ such that (, ) = 2. The hop domination number of a graph , denoted by ℎ(), is the minimum cardinality of a hop dominating set of . We prove that for every tree of order with leaves and support vertices we have (−− +4)/3 ≤ ℎ() ≤ /2, and characterize the trees attaining each of the bounds.

  11. Multiphonon hopping of carriers in CuO thin films

    Science.gov (United States)

    Serin, T.; Yildiz, A.; Şahin, Ş. H.; Serin, N.

    2011-10-01

    We have performed a detailed study of the electrical conduction process in CuO thin films deposited by the sol-gel dip coating technique in a temperature range 280-420 K. The electrical conduction is analyzed within the framework of various hopping conduction models. Multiphonon hopping conduction mechanism is found to dominate the electrical transport in the entire temperature region. Our results are consistent with this model of hopping conduction mechanisms with weak carrier-lattice coupling.

  12. Nonmagnetic rigid and flexible outer sheath with pneumatic interlocking mechanism for minimally invasive surgical approach.

    Science.gov (United States)

    Yamashita, Hiromasa; Zuo, Siyang; Masamune, Ken; Liao, Hongen; Dohi, Takeyoshi

    2009-01-01

    We developed a nonmagnetic rigid and flexible outer sheath with pneumatic interlocking mechanism using flexible toothed links and a wire-driven bending distal end. The outer sheath can be switched between rigid and flexible modes easily depending on surgical scenes, and the angle of its distal end can be controlled by three nylon wires. All components of flexible parts are made of MRI-compatible nonmagnetic plastics. We manufactured the device with 300-mm long, 16-mm outer diameter, 7-mm inner diameter and 90-mm bending distal end. Holding power of the device in rigid mode was maximum 3.6 N, which was sufficient for surgical tasks in body cavity. In vivo experiment using a swine, our device performed smooth insertion of a flexible endoscope and a biopsy forceps into reverse side of the liver, intestines and spleen with a curved path. In conclusion, our device shows availability of secure approach of surgical instruments into deep cavity.

  13. Designing the coordinate transformation function for non-magnetic invisibility cloaking

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xiaofei; Feng Yijun; Zhao Lin; Jiang Tian [Department of Electronic Science and Engineering, Nanjing University, Nanjing, 210093 (China); Lu Chunhua; Xu Zhongzi [College of Materials Science and Engineering, Nanjing University of Technology, Nanjing, 210009 (China)], E-mail: yjfeng@nju.edu.cn

    2008-11-07

    An optical invisibility cloak based on a transformation approach has recently been proposed by a reduced set of material properties due to their easier implementation in reality and little need for an inhomogeneous permeability distribution, but the drawback of undesired scattering caused by the impedance mismatching at the outer boundary is unavoidable in such a cloak. By properly designing the coordinate transformation function to ensure impedance matching at the outer surface, we show that the performance of a nonmagnetic cylindrical cloak could be improved with minimized scattering fields. Using either a single high order power function or an optimized piecewise continuous power function, a cylindrical non-magnetic cloak has been designed with nearly perfect cloaking performance, which is better than those generated with a linear or a quadratic function. Due to the monotonicity of the designed power functions, the resulting cloak has no restriction on the size of the cloaking shell, therefore is suitable for both thick and thin cloaking structures.

  14. Thermal spin current and spin accumulation at ferromagnetic insulator/nonmagnetic metal interface

    Science.gov (United States)

    Shen, Y. H.; Wang, X. S.; Wang, X. R.

    2016-07-01

    Spin current injection and spin accumulation near a ferromagnetic insulator (FI)/nonmagnetic metal (NM) bilayer film under a thermal gradient is investigated theoretically. By using the Fermi golden rule and the Boltzmann equations, we find that FI and NM can exchange spins via interfacial electron-magnon scattering because of the imbalance between magnon emission and absorption caused by either the deviation of the magnon number from the equilibrium Bose-Einstein distribution or the difference in magnon temperature and electron temperature. A temperature gradient in FI and/or a temperature difference across the FI/NM interface generates a spin current which carries angular momenta parallel to the magnetization of FI from the hotter side to the colder one. Interestingly, the spin current induced by a temperature gradient in NM is negligibly small due to the nonmagnetic nature of the nonequilibrium electron distributions. The results agree well with all existing experiments.

  15. Radiation-Suppressed plasmonic open resonators designed by nonmagnetic transformation optics

    Science.gov (United States)

    Xu, Hongyi; Wang, Xingjue; Yu, Tianyuan; Sun, Handong; Zhang, Baile

    2012-01-01

    How to confine light energy associated with surface plasmon polaritons (SPPs) in a physical space with minimal radiation loss whereas creating maximum interacting section with surrounding environment is of particular interest in plasmonic optics. By virtue of transformation optics, we propose a design method of forming a polygonal surface-plasmonic resonator in fully open structures by applying the nonmagnetic affine transformation optics strategy. The radiation loss can be suppressed because SPPs that propagate in the designed open structures will be deceived as if they were propagating on a flat metal/dielectric interface without radiation. Because of the nonmagnetic nature of the transformation strategy, this design can be implemented with dielectric materials available in nature. An experimentally verifiable model is subsequently proposed for future experimental demonstration. Our design may find potential applications in omnidirectional sensing, light harvesting, energy storage and plasmonic lasing. PMID:23136641

  16. Enhanced spin-torque in double tunnel junctions using a nonmagnetic-metal spacer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C. H.; Cheng, Y. H.; Ko, C. W.; Hsueh, W. J., E-mail: hsuehwj@ntu.edu.tw [Nanomagnetism Group, Department of Engineering Science and Ocean Engineering, National Taiwan University, 1, Sec. 4, Roosevelt Road, Taipei 10660, Taiwan (China)

    2015-10-12

    This study proposes an enhancement in the spin-transfer torque of a magnetic tunnel junction (MTJ) designed with double-barrier layer structure using a nonmagnetic metal spacer, as a replacement for the ferromagnetic material, which is traditionally used in these double-barrier stacks. Our calculation results show that the spin-transfer torque and charge current density of the proposed double-barrier MTJ can be as much as two orders of magnitude larger than the traditional double-barrier one. In other words, the proposed double-barrier MTJ has a spin-transfer torque that is three orders larger than that of the single-barrier stack. This improvement may be attributed to the quantum-well states that are formed in the nonmagnetic metal spacer and the resonant tunneling mechanism that exists throughout the system.

  17. Spin selector based on periodic diluted-magnetic-semiconductor/nonmagnetic-barrier superlattices

    Directory of Open Access Journals (Sweden)

    Ping-Fan Yang

    2015-07-01

    Full Text Available We propose a spin selector based on periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB superlattices subjected to an external magnetic field. We find that the periodic DMS/NB superlattices can achieve 100% spin filtering over a dramatically broader range of incident energies than the diluted-magnetic-semiconductor/semiconductor (DMS/S case studied previously. And the positions and widths of spin-filtering bands can be manipulated effectively by adjusting the geometric parameters of the system or the strength of external magnetic field. Such a compelling filtering feature stems from the introduction of nonmagnetic barrier and the spin-dependent giant Zeeman effect induced by the external magnetic field. We also find that the external electric field can exert a significant influence on the spin-polarized transport through the DMS/NB superlattices.

  18. Spin selector based on periodic diluted-magnetic-semiconductor/nonmagnetic-barrier superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ping-Fan; Guo, Yong, E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Zhu, Rui [Department of Physics, South China University of Technology, Guangzhou 510641 (China)

    2015-07-15

    We propose a spin selector based on periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB) superlattices subjected to an external magnetic field. We find that the periodic DMS/NB superlattices can achieve 100% spin filtering over a dramatically broader range of incident energies than the diluted-magnetic-semiconductor/semiconductor (DMS/S) case studied previously. And the positions and widths of spin-filtering bands can be manipulated effectively by adjusting the geometric parameters of the system or the strength of external magnetic field. Such a compelling filtering feature stems from the introduction of nonmagnetic barrier and the spin-dependent giant Zeeman effect induced by the external magnetic field. We also find that the external electric field can exert a significant influence on the spin-polarized transport through the DMS/NB superlattices.

  19. Hidden spin polarization in nonmagnetic centrosymmetric BaNiS2 crystal: Signatures from first principles

    Science.gov (United States)

    Sławińska, Jagoda; Narayan, Awadhesh; Picozzi, Silvia

    2016-12-01

    The recent discovery of hidden spin polarization emerging in bulk electronic states of specific nonmagnetic crystals is a fascinating phenomenon, though hardly explored yet. Here, we study from a theoretical perspective nonmagnetic BaNiS2, recently suggested to exhibit a giant Rashba-like spin-orbit splitting of the bulk bands, despite the absence of heavy elements. We employ density functional theory and Green's functions calculations to reveal the exact spin textures of both bulk and surface. We predict unambiguous signatures of spin-polarized electronic states at the surface, which reflect the bulk Rashba splitting and which could be experimentally measured with sufficient resolution: this would constitute a clear report of a bulk-Rashba-induced spin splitting at the surface of centrosymmetric crystals.

  20. Impure placebo is a useless concept.

    Science.gov (United States)

    Louhiala, Pekka; Hemilä, Harri; Puustinen, Raimo

    2015-08-01

    Placebos are allegedly used widely in general practice. Surveys reporting high level usage, however, have combined two categories, 'pure' and 'impure' placebos. The wide use of placebos is explained by the high level usage of impure placebos. In contrast, the prevalence of the use of pure placebos has been low. Traditional pure placebos are clinically ineffective treatments, whereas impure placebos form an ambiguous group of diverse treatments that are not always ineffective. In this paper, we focus on the impure placebo concept and demonstrate problems related to it. We also show that the common examples of impure placebos are not meaningful from the point of view of clinical practice. We conclude that the impure placebo is a scientifically misleading concept and should not be used in scientific or medical literature. The issues behind the concept, however, deserve serious attention in future research.

  1. Overview of genotoxic impurities in pharmaceutical development.

    Science.gov (United States)

    Bercu, Joel P; Dobo, Krista L; Gocke, Elmar; McGovern, Timothy J

    2009-01-01

    This symposium focuses on the management of genotoxic impurities in the synthesis of pharmaceuticals. Recent developments in both Europe and United States require sponsors of new drug applications to develop processes to control the risks of potential genotoxic impurities. Genotoxic impurities represent a special case relative to the International Conference on Harmonisation Q3A/Q3B guidances, because genotoxicity tests used to qualify the drug substance may not be sufficient to demonstrate safety of a potentially genotoxic impurity. The default risk management approach for a genotoxic impurity is the threshold of toxicological concern unless a more specific risk characterization is appropriate. The symposium includes descriptions of industry examples where impurities are introduced and managed in the synthesis of a pharmaceutical. It includes recent regulatory developments such as the "staged threshold of toxicological concern" when administration is of short duration (eg, during clinical trials).

  2. Moessbauer Studies of Implanted Impurities in Solids

    CERN Multimedia

    2002-01-01

    Moessbauer studies were performed on implanted radioactive impurities in semiconductors and metals. Radioactive isotopes (from the ISOLDE facility) decaying to a Moessbauer isotope were utilized to investigate electronic and vibrational properties of impurities and impurity-defect structures. This information is inferred from the measured impurity hyperfine interactions and Debye-Waller factor. In semiconductors isoelectronic, shallow and deep level impurities have been implanted. Complex impurity defects have been produced by the implantation process (correlated damage) or by recoil effects from the nuclear decay in both semiconductors and metals. Annealing mechanisms of the defects have been studied. \\\\ \\\\ In silicon amorphised implanted layers have been recrystallized epitaxially by rapid-thermal-annealing techniques yielding highly supersaturated, electrically-active donor concentrations. Their dissolution and migration mechanisms have been investigated in detail. The electronic configuration of Sb donors...

  3. Temperature profile along an induction heated, moving non-magnetic charge

    Energy Technology Data Exchange (ETDEWEB)

    Januszkiewicz, K.

    1984-01-01

    Induction heating system, comprising three sections of a heating coil connected in series and supplied from one source, will be discussed. The charge to be heated is a non-magnetic pipe moving with steady speed. The heating coil is water cooled. Digital methods are used to compute temperature variations along the charge from start up to steady state temperature and also to determine power development in the heating circuit. Cooling zones between the heating coil sections are taken into account.

  4. Simulation of Electron Beam Dynamics in a Nonmagnetized High-Current Vacuum Diode

    CERN Document Server

    Anishchenko, Sergey

    2016-01-01

    The electron beam dynamics in a nonmagnetized high-current vacuum diode is analyzed for different cathode-anode gap geometries. The conditions enabling to achieve the minimal {initial} momentum spread in the electron beam are found out. A drastic rise of current density in a vacuum diode with a ring-type cathode is described. The effect is shown to be caused by electrostatic repulsion.

  5. Terrain dependant hop count selection for transparent relay transmissions

    Directory of Open Access Journals (Sweden)

    Cibile K. Kanjirathumkal

    2013-12-01

    Full Text Available In this Letter, the selection of the best hop count for a particular topography, in the context of enhanced connectivity using multi-hop transparent relay communication is addressed. Based on the coefficient of variation and the terrain specific fading severity factor of the distribution, it is possible to estimate the optimal hop count that can provide the required performance at detector. Two distribution models, which can adequately characterise the terrain fading effects on empirical data are considered for performance comparison. The results are useful in selecting branches, with low variability and optimal hop count for connectivity, in multi-stream switched diversity combining systems.

  6. The space density and X-ray luminosity function of non-magnetic cataclysmic variables

    CERN Document Server

    Pretorius, Magaretha L

    2011-01-01

    We combine two complete, X-ray flux-limited surveys, the ROSAT Bright Survey (RBS) and the ROSAT North Ecliptic Pole (NEP) survey, to measure the space density (\\rho) and X-ray luminosity function (\\Phi) of non-magnetic CVs. The combined survey has a flux limit of F_X \\ga 1.1 \\times 10^{-12} erg cm^{-2}s^{-1} over most of its solid angle of just over 2\\pi, but is as deep as \\simeq 10^{-14} erg cm^{-2}s^{-1} over a small area. The CV sample that we construct from these two surveys contains 20 non-magnetic systems. We carefully include all sources of statistical error in calculating \\rho and \\Phi by using Monte Carlo simulations; the most important uncertainty proves to be the often large errors in distances estimates. If we assume that the 20 CVs in the combined RBS and NEP survey sample are representative of the intrinsic population, the space density of non-magnetic CVs is 4^{+6}_{-2} \\times 10^{-6} pc^{-3}. We discuss the difficulty in measuring \\Phi in some detail---in order to account for biases in the me...

  7. Valley and spin resonant tunneling current in ferromagnetic/nonmagnetic/ferromagnetic silicene junction

    Directory of Open Access Journals (Sweden)

    Yaser Hajati

    2016-02-01

    Full Text Available We study the transport properties in a ferromagnetic/nonmagnetic/ferromagnetic (FNF silicene junction in which an electrostatic gate potential, U, is attached to the nonmagnetic region. We show that the electrostatic gate potential U is a useful probe to control the band structure, quasi-bound states in the nonmagnetic barrier as well as the transport properties of the FNF silicene junction. In particular, by introducing the electrostatic gate potential, both the spin and valley conductances of the junction show an oscillatory behavior. The amplitude and frequency of such oscillations can be controlled by U. As an important result, we found that by increasing U, the second characteristic of the Klein tunneling is satisfied as a result of the quasiparticles chirality which can penetrate through a potential barrier. Moreover, it is found that for special values of U, the junction shows a gap in the spin and valley-resolve conductance and the amplitude of this gap is only controlled by the on-site potential difference, Δz. Our findings of high controllability of the spin and valley transport in such a FNF silicene junction may improve the performance of nano-electronics and spintronics devices.

  8. Method for detecting trace impurities in gases

    Science.gov (United States)

    Freund, S.M.; Maier, W.B. II; Holland, R.F.; Beattie, W.H.

    A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (approx. 2 ppM) present in commercial Xe and ppM levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

  9. Analytical advances in pharmaceutical impurity profiling.

    Science.gov (United States)

    Holm, René; Elder, David P

    2016-05-25

    Impurities will be present in all drug substances and drug products, i.e. nothing is 100% pure if one looks in enough depth. The current regulatory guidance on impurities accepts this, and for drug products with a dose of less than 2g/day identification of impurities is set at 0.1% levels and above (ICH Q3B(R2), 2006). For some impurities, this is a simple undertaking as generally available analytical techniques can address the prevailing analytical challenges; whereas, for others this may be much more challenging requiring more sophisticated analytical approaches. The present review provides an insight into current development of analytical techniques to investigate and quantify impurities in drug substances and drug products providing discussion of progress particular within the field of chromatography to ensure separation of and quantification of those related impurities. Further, a section is devoted to the identification of classical impurities, but in addition, inorganic (metal residues) and solid state impurities are also discussed. Risk control strategies for pharmaceutical impurities aligned with several of the ICH guidelines, are also discussed.

  10. Behavior of impurities in TRIAM-IM

    Energy Technology Data Exchange (ETDEWEB)

    Takashiri, Masayuki; Nakamura, Kazuo; Kawasaki, Shoji; Jotaki, Eriko; Makino, Kenichi; Ito, Sanae; Ito, Satoshi [Kyushu Univ., Fukuoka (Japan)

    1994-09-01

    This research is the spectroscopic research on the behavior of impurities in the superconducting strong magnetic field tokamak, TRIAM-1M. In the experiment at the TRIAM-1M, the steady operation of the tokamak by the current drive using 8.2 GHz low hybrid waves has been aimed at toward the practical use of nuclear fusion reactors. In this research, the design and manufacture of the spectroscope system for diagnosing the behavior of impurities and the evaluation of the amount of impurities and effective charge number were carried out. The main impurities were metallic impurities of molybdenum, iron and chrome, and light element impurity of oxygen. The spatial distribution measurement was performed by using a multi-channel vacuum ultraviolet spectroscope system for the spectrum line intensity, and the change with time lapse of the radial distribution of impurity amount was derived. As the results, the amounts of iron and chrome which are the impurities of stainless steel system rapidly increased at plasma center in the latter half of discharge. The increase of the molybdenum amount which is the limiter material was small as compared with iron and chrome, and the amount of oxygen impurity hardly changed throughout discharge. The change with time lapse of the effective charge number in radial distribution was from 4 to 6 during discharge. (K.I.).

  11. Magnetoresistance generated from charge-spin conversion by anomalous Hall effect in metallic ferromagnetic/nonmagnetic bilayers

    Science.gov (United States)

    Taniguchi, Tomohiro

    2016-11-01

    A theoretical formulation of magnetoresistance effect in a metallic ferromagnetic/nonmagnetic bilayer originated from the charge-spin conversion by the anomalous Hall effect is presented. Analytical expressions of the longitudinal and transverse resistivities in both nonmagnet and ferromagnet are obtained by solving the spin diffusion equation. The magnetoresistance generated from charge-spin conversion purely caused by the anomalous Hall effect in the ferromagnet is found to be proportional to the square of the spin polarizations in the ferromagnet and has fixed sign. We also find additional magnetoresistances in both nonmagnet and ferromagnet arising from the mixing of the spin Hall and anomalous Hall effects. The sign of this mixing resistance depends on those of the spin Hall angle in the nonmagnet and the spin polarizations of the ferromagnet.

  12. Security for multi-hop wireless networks

    CERN Document Server

    Mahmoud, Mohamed M E A

    2014-01-01

    This Springer Brief discusses efficient security protocols and schemes for multi-hop wireless networks. It presents an overview of security requirements for these networks, explores challenges in securing networks and presents system models. The authors introduce mechanisms to reduce the overhead and identify malicious nodes that drop packets intentionally. Also included is a new, efficient cooperation incentive scheme to stimulate the selfish nodes to relay information packets and enforce fairness. Many examples are provided, along with predictions for future directions of the field. Security

  13. Optimal Hops-Based Adaptive Clustering Algorithm

    Science.gov (United States)

    Xuan, Xin; Chen, Jian; Zhen, Shanshan; Kuo, Yonghong

    This paper proposes an optimal hops-based adaptive clustering algorithm (OHACA). The algorithm sets an energy selection threshold before the cluster forms so that the nodes with less energy are more likely to go to sleep immediately. In setup phase, OHACA introduces an adaptive mechanism to adjust cluster head and load balance. And the optimal distance theory is applied to discover the practical optimal routing path to minimize the total energy for transmission. Simulation results show that OHACA prolongs the life of network, improves utilizing rate and transmits more data because of energy balance.

  14. Hip—hop Music嘻哈乐

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Hip—Hop(嘻哈)文化源于上世纪七十年代美国黑人的一种街头说唱文化。在几十年的时间内,Hip—Hop文化也由一开始的打碟、说唱乐、街舞、涂鸦四个基本单元发展到包括滑板、街头篮球等表演性质的体育运动。现已蔓延到世界各地,深受年轻人的喜爱和欢迎。

  15. Collision-based mechanics of bipedal hopping.

    Science.gov (United States)

    Gutmann, Anne K; Lee, David V; McGowan, Craig P

    2013-08-23

    The muscle work required to sustain steady-speed locomotion depends largely upon the mechanical energy needed to redirect the centre of mass and the degree to which this energy can be stored and returned elastically. Previous studies have found that large bipedal hoppers can elastically store and return a large fraction of the energy required to hop, whereas small bipedal hoppers can only elastically store and return a relatively small fraction. Here, we consider the extent to which large and small bipedal hoppers (tammar wallabies, approx. 7 kg, and desert kangaroo rats, approx. 0.1 kg) reduce the mechanical energy needed to redirect the centre of mass by reducing collisions. We hypothesize that kangaroo rats will reduce collisions to a greater extent than wallabies since kangaroo rats cannot elastically store and return as high a fraction of the mechanical energy of hopping as wallabies. We find that kangaroo rats use a significantly smaller collision angle than wallabies by employing ground reaction force vectors that are more vertical and center of mass velocity vectors that are more horizontal and thereby reduce their mechanical cost of transport. A collision-based approach paired with tendon morphometry may reveal this effect more generally among bipedal runners and quadrupedal trotters.

  16. HopBase: A unified resource for Humulus genomics

    Science.gov (United States)

    Hop (Humulus lupulus L. var lupulus) is a plant of worldwide significance, used primarily for its’ bittering and flavoring in brewing beer. Studies on the medicinal properties of several unique compounds produced by hop has led to additional interest from pharmacy and healthcare industries as well a...

  17. Hop powdery mildew control through alteration of spring pruning practices

    Science.gov (United States)

    Since 1997, Podosphaera macularis, the causal agent of hop powdery mildew, has become a recurrent threat to hops in the Pacific Northwest because of the potential to reduce cone yield and quality. Disease management practices often involve preventative fungicide applications, but alternative approac...

  18. Hip Hop as Empowerment: Voices in El Alto, Bolivia

    Science.gov (United States)

    Tarifa, Ariana

    2012-01-01

    In response to neoliberal policies that have been in place since 1985, Bolivian young people have increasingly used hip hop music as a means of protest and to reclaim social and political participation. Hip hop in Latin America tells the story of the struggles that marginalized people have suffered, and speaks to the effects of international…

  19. Being Hip-Hop: Beyond Skills and Songs

    Science.gov (United States)

    Kruse, Adam J.

    2016-01-01

    In this article, I offer four principles relevant to hip-hop cultures (keep it real, flip the script, make some noise, and stay fresh) and explore how these principles might affect music classrooms. I argue that a music classroom that works to keep it real, flip the script, make some noise, and stay fresh might go beyond teaching hip-hop skills…

  20. Gap solitons in periodic Schrodinger lattice system with nonlinear hopping

    Directory of Open Access Journals (Sweden)

    Ming Cheng

    2016-10-01

    Full Text Available This article concerns the periodic discrete Schrodinger equation with nonlinear hopping on the infinite integer lattice. We obtain the existence of gap solitons by the linking theorem and concentration compactness method together with a periodic approximation technique. In addition, the behavior of such solutions is studied as $\\alpha\\to 0$. Notice that the nonlinear hopping can be sign changing.

  1. Hip Hop as Empowerment: Voices in El Alto, Bolivia

    Science.gov (United States)

    Tarifa, Ariana

    2012-01-01

    In response to neoliberal policies that have been in place since 1985, Bolivian young people have increasingly used hip hop music as a means of protest and to reclaim social and political participation. Hip hop in Latin America tells the story of the struggles that marginalized people have suffered, and speaks to the effects of international…

  2. [Hopping and superexchange mechanisms of charge transport to DNA].

    Science.gov (United States)

    Lakhno, V D; Sultanov, V B

    2003-01-01

    A theory for charge transport in nucleobase sequences was constructed in which the hole migration proceeds via hopping between guanines. Each hop over the adenine-thymine (A-T) bridge connecting neighboring guanines occurs by means of the superexchange mechanism. The experimental data and theoretical results for various types of nucleobase sequences are compared.

  3. Chicano Hip-Hop as Interethnic Contact Zone

    Science.gov (United States)

    McFarland, Pancho

    2008-01-01

    The critical study of rap music and hip-hop culture has the potential to expand Americans understanding of race and culture in the United States. Hip-hop culture as a multiracial, multiethnic phenomenon reveals the ways in which race relations over the past thirty years have become increasingly complex. The theories and concepts that they use to…

  4. Christian Hip Hop as Pedagogy: A South African Case Study

    Science.gov (United States)

    Abraham, Ibrahim

    2015-01-01

    Drawing on interviews with creators of Christian hip hop music in South Africa, this article demonstrates that this genre of popular music and youth culture is utilised as a form of pedagogy to transmit religious beliefs and values to contemporary youth. The pedagogical aspects of hip hop have been recognised in research on the topic, but the…

  5. Cryogenic Laser Calorimetry for Impurity Analysis

    Science.gov (United States)

    Swimm, R. T.

    1985-01-01

    The results of a one-year effort to determine the applicability of laser-calorimetric spectroscopy to the study of deep-level impurities in silicon are presented. Critical considerations for impurity analysis by laser-calorimetric spectroscopy are discussed, the design and performance of a cryogenic laser calorimeter is described, and measurements of background absorption in high-purity silicon are presented.

  6. Nuclear relaxation via paramagnetic impurities

    CERN Document Server

    Dzheparov, F S; Jacquinot, J F

    2002-01-01

    First part of the work contains a calculation of the kinetics of nuclear relaxation via paramagnetic impurities for systems with arbitrary (including fractal) space dimension d basing on ideas, which run current for 3d objects now. A new mean-field-type theory is constructed in the second part of the work. It reproduces all results of the first part for integer d and gives a possibility to describe the process for longer time, when a crossover to Balagurov-Waks asymptotics starts to develop. Solutions of the equations of the new theory are constructed for integer d. To obtain the solutions a method of calculation of the low-energy and long-wave asymptotics for T matrix of potential scattering out of the mass shell for singular repulsive potentials is developed

  7. Neoclassical impurity transport in stellarator geometry

    CERN Document Server

    García-Regaña, J M; Beidler, C D; berg, H Maaß; Helander, P; Turkin, Y

    2012-01-01

    The impurity dynamics in stellarators has become an issue of moderate concern due to the, \\textit{a priori}, inherent tendency of the impurities to accumulate in the core when the neoclassical ambipolar radial electric field points radially inwards (ion root regime). This accumulation can lead to collapse of the plasma due to radiative losses, and thus limit high performance plasma discharges in non-axisymmetric devices. Theoretically, a quantitative description of the neoclassical impurity transport is complicated by the breakdown of the assumption of small $q \\tilde{\\Phi}/T$ for impurities, where $q$ is the electric charge, $T$ the temperature in energy units, and $\\tilde{\\Phi}$ the electrostatic potential variation within the flux surface. The present work describes quantitatively the particle transport of impurities in the frame of local neoclassical theory when $q\\tilde{\\Phi}/T=O(1)$ in the Large Helical Device (LHD) stellarator. %and the Wendelstein 7-X stellarators. The central numerical tool used is t...

  8. Analytical control of process impurities in Pazopanib hydrochloride by impurity fate mapping.

    Science.gov (United States)

    Li, Yan; Liu, David Q; Yang, Shawn; Sudini, Ravinder; McGuire, Michael A; Bhanushali, Dharmesh S; Kord, Alireza S

    2010-08-01

    Understanding the origin and fate of organic impurities within the manufacturing process along with a good control strategy is an integral part of the quality control of drug substance. Following the underlying principles of quality by design (QbD), a systematic approach to analytical control of process impurities by impurity fate mapping (IFM) has been developed and applied to the investigation and control of impurities in the manufacturing process of Pazopanib hydrochloride, an anticancer drug approved recently by the U.S. FDA. This approach requires an aggressive chemical and analytical search for potential impurities in the starting materials, intermediates and drug substance, and experimental studies to track their fate through the manufacturing process in order to understand the process capability for rejecting such impurities. Comprehensive IFM can provide elements of control strategies for impurities. This paper highlights the critical roles that analytical sciences play in the IFM process and impurity control. The application of various analytical techniques (HPLC, LC-MS, NMR, etc.) and development of sensitive and selective methods for impurity detection, identification, separation and quantification are highlighted with illustrative examples. As an essential part of the entire control strategy for Pazopanib hydrochloride, analytical control of impurities with 'meaningful' specifications and the 'right' analytical methods is addressed. In particular, IFM provides scientific justification that can allow for control of process impurities up-stream at the starting materials or intermediates whenever possible.

  9. Impurity levels, impurity bands, excited impurity bands, and band tails: The electronic density of states in quantum wells and heterostructures

    Science.gov (United States)

    Serre, J.; Ghazali, A.; Gold, A.

    1989-04-01

    We have investigated in quantum wells (QW's) and heterostructures (HS's) the modification of the electronic structure near the band edge, which is induced by selective doping. The density of states has been calculated as a function of the relevant parameters, namely, carrier and impurity concentrations (and depletion concentrations for HS's), QW width, and impurity position. Using a multiple-scattering method which includes a finite-range screened potential and impurity concentration to all orders, we have succeeded in obtaining ground-state and excited-state impurity bands (IB's). We observed these bands merging gradually with the lowest conduction subband as the impurity concentration is increased, leading to the formation of a band tail into the energy gap. Other main results obtained for different values of the parameters are the binding energy for a single impurity, the widths and energy shifts of ground- and excited-state IB's, and the contribution of the electron-impurity interaction to the gap shrinkage in the band-tail regime. Our results are compared with experiments and other theories.

  10. Peculiarities of hopping conduction in p-Hg sub 0 sub . sub 7 sub 8 Cd sub 0 sub . sub 2 sub 2 Te crystals at binary doping

    CERN Document Server

    Bogoboyashchij, V V

    2002-01-01

    Electric conductivity and the Hall effect within the 4.2-125 K temperature range have been investigated in p-Hg sub 0 sub . sub 7 sub 8 Cd sub 0 sub . sub 2 sub 2 Te crystals, containing 3 x 10 sup 1 sup 6 cm sup - sup 3 of copper impurities and 1.83 x 10 sup 1 sup 6 cm sup - sup 3 of mercury vacancies (together or separately). The epsilon sub 1 -conductivity due to free holes above 10-12 K and the hopping conductivity below 8-10 K are dominant in such crystals respectively. It was found that the epsilon sub 1 -conductivity in copper-doped crystals is independent of the vacancy presence, while the hopping conductivity essentially increases due to the vacancy availability. This phenomenon is explained in terms hole joining neutral mercury vacancies.The binding energy is calculated; it equal 3.7 meV in background state

  11. Pairing Symmetry Studied from Impurity Effects in the Undoped Superconductor T'-La1.8Eu0.2CuO4

    Science.gov (United States)

    Ohashi, Koki; Kawamata, Takayuki; Takamatsu, Tomohisa; Adachi, Tadashi; Kato, Masatsune; Koike, Yoji

    2016-09-01

    We have investigated the effects of magnetic Ni and nonmagnetic Zn impurities on the superconductivity in undoped T'-La1.8Eu0.2CuO4 (T'-LECO) with the Nd2CuO4-type structure, using polycrystalline bulk samples, to clarify the pairing symmetry. It has been found that the suppression rates of the superconducting transition temperature Tc by both Ni and Zn impurities are nearly the same and are very similar to those in the optimally doped and overdoped regimes of hole-doped T-La2-xSrxCuO4 with the K2NiF4-type structure. These results strongly suggest that the superconductivity in undoped T'-LECO has d-wave symmetry and is mediated by the spin fluctuation.

  12. HRCT: hop-by-hop rate control technique for congestion control in wireless sensor network

    Science.gov (United States)

    Chakravarthi, Rekha; Cidambaram, Gomathy

    2011-12-01

    In Wireless Sensor Networks, congestion occurs when the traffic rate is high. This happens when the an event is detected in a network. Congestion causes packet loss thus degrading the performance of the network. Hence it necessitates to develop an effective congestion control technique. This paper focuses on congestion due to concurrent transmission. We have proposed an efficient protocol to detect and control congestion in a MAC. The occurrence of congestion is detected by calculating a new metrics called congestion scale. When the congestion scale exceeds the threshold value it intimates, that, congestion has occurred. Congestion notification signal is send to all the nodes. On receiving the notification signal all nodes adjust their transmission rate to control congestion. We have implemented Hop-by-Hop Rate Control Technique(HRCT) to control congestion and to guarantee both high throughput and minimum delay. This technique is implemented successfully in NS-2 simulator. Finally, simulation results have demonstrated the effectiveness of our proposed algorithm.

  13. Non-magnetic simplified cylindrical cloak with suppressed zero-th order scattering

    CERN Document Server

    Yan, Wei; Qiu, Min

    2008-01-01

    A new type of simplified cloaks with matched exterior boundaries is proposed. The cloak uses non-magnetic material for the TM polarization and can function with a relatively thin thickness. It is shown that the $zero^{th}$ order scattering of such cloak is dominant among all cylindrical scattering terms. A gap is added at the cloak's inner surface to eliminate the zero-th order scattering, through the mechanism of scattering resonance. The reduction in scattering is relatively smooth, indicating that the proposed scattering reduction method has good tolerance to perturbations. Numerical simulations also confirm that the proposed structure has very low scattering.

  14. Few-layer graphene shells and nonmagnetic encapsulates: a versatile and nontoxic carbon nanomaterial.

    Science.gov (United States)

    Bachmatiuk, Alicja; Mendes, Rafael G; Hirsch, Cordula; Jähne, Carsten; Lohe, Martin R; Grothe, Julia; Kaskel, Stefan; Fu, Lei; Klingeler, Rüdiger; Eckert, Jürgen; Wick, Peter; Rümmeli, Mark H

    2013-12-23

    In this work a simple and scalable approach to coat nonmagnetic nanoparticles with few-layer graphene is presented. In addition, the easy processing of such nanoparticles to remove their core, leaving only the 3D graphene nanoshell, is demonstrated. The samples are comprehensively characterized, as are their versatility in terms of functionalization and as a material for electrochemical storage. Indeed, these 3D graphene nanostructures are easily functionalized much as is found with carbon nanotubes and planar graphene. Electrochemical investigations indicate these nanostructures are promising for stable long-life battery applications. Finally, initial toxicological investigations suggest no acute health risk from these 3D graphene nanostructures.

  15. Magnetism of Rare-Earth Compounds with Non-Magnetic Crystal-Field Ground Levels

    Institute of Scientific and Technical Information of China (English)

    LIU Zhao-Sen

    2007-01-01

    @@ Among rare-earth compounds, there are many materials having non-magnetic crystal-field (CF) ground levels.To understand their magnetic behaviour at low temperatures, we study the effects of the CF levels and the Heisenberg-like coupling on the magnetic process of such a crystalline with mean-field and CF theory. It is found that the material can be magnetically ordered if the Heisenberg exchange is sufficiently strong. Additionally we obtain a condition for initial magnetic ordering, and derive a formula for estimating the Curie temperature if the ordering occurs.

  16. Spin-current-induced magnetoresistance in trilayer structure with nonmagnetic metallic interlayer

    Science.gov (United States)

    Iguchi, Ryo; Sato, Koji; Uchida, Ken-ichi; Saitoh, Eiji

    2017-04-01

    We have theoretically investigated the spin Hall magnetoresistance (SMR) and Rashba–Edelstein magnetoresistance (REMR), mediated by spin currents, in a ferrimagnetic insulator/nonmagnetic metal/heavy metal system in the diffusive regime. The magnitude of both SMR and REMR decreases with increasing thickness of the interlayer because of the current shunting effect and the reduction in spin accumulation across the interlayer. The latter contribution is due to driving a spin current and persists even in the absence of spin relaxation, which is essential for understanding the magnetoresistance ratio in trilayer structures.

  17. Position feedback control of a nonmagnetic body levitated in magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J H; Nam, Y J; Park, M K [Graduate School, Pusan National University, Busan 609-735 (Korea, Republic of); Yamane, R [Kokushikan University, Tokyo 154-8515 (Japan)], E-mail: magooro@pusan.ac.kr

    2009-02-01

    This paper is concerned with the position feedback control of a magnetic fluid actuator which is characterized by the passive levitation of a nonmagnetic body immersed in a magnetic fluid under magnetic fields. First of all, the magnetic fluid actuator is designed based on the ferrohydrostatic relation. After manufacturing the actuator, its static and dynamic characteristics are investigated experimentally. With the aid of the dynamic governing relation obtained experimentally and the proportional-derivative controller, the position tracking control of the actuator is carried out both theoretically and experimentally. As a result, the applicability of the proposed magnetic fluid actuator to various engineering devices is verified.

  18. The space density and X-ray luminosity function of non-magnetic cataclysmic variables

    Science.gov (United States)

    Pretorius, Magaretha L.; Knigge, Christian

    2012-01-01

    We combine two complete, X-ray flux-limited surveys, the ROSAT Bright Survey (RBS) and the ROSAT North Ecliptic Pole (NEP) survey, to measure the space density (ρ) and X-ray luminosity function (Φ) of non-magnetic cataclysmic variables (CVs). The combined survey has a flux limit of FX≳ 1.1 × 10-12 erg cm-2 s-1 over most of its solid angle of just over ?, but is as deep as ≃10-14 erg cm-2 s-1 over a small area. The CV sample that we construct from these two surveys contains 20 non-magnetic systems. We carefully include all sources of statistical error in calculating ρ and Φ by using Monte Carlo simulations; the most important uncertainty proves to be the often large errors in distances estimates. If we assume that the 20 CVs in the combined RBS and NEP survey sample are representative of the intrinsic population, the space density of non-magnetic CVs is ?. We discuss the difficulty in measuring Φ in some detail - in order to account for biases in the measurement, we have to adopt a functional form for Φ. Assuming that the X-ray luminosity function of non-magnetic CVs is a truncated power law, we constrain the power-law index to -0.80 ± 0.05. It seems likely that the two surveys have failed to detect a large, faint population of short-period CVs, and that the true space density may well be a factor of 2 or 3 larger than what we have measured; this is possible, even if we only allow for undetected CVs to have X-ray luminosities in the narrow range 28.7 log(LX/erg s-1) < 29.7. However, ρ as high as 2 × 10-4 pc-3 would require that the majority of CVs has X-ray luminosities below LX= 4 × 1028 erg s-1 in the 0.5-2.0 keV band.

  19. Induction heating of rotating nonmagnetic billet in magnetic field produced by high-parameter permanent magnets

    Directory of Open Access Journals (Sweden)

    Ivo Doležel

    2014-04-01

    Full Text Available An advanced way of induction heating of nonmagnetic billets is discussed and modeled. The billet rotates in a stationary magnetic field produced by unmoving high-parameter permanent magnets fixed on magnetic circuit of an appropriate shape. The mathematical model of the problem consisting of two coupled partial differential equations is solved numerically, in the monolithic formulation. Computations are carried out using our own code Agros2D based on a fully adaptive higher-order finite element method. The most important results are verified experimentally on our own laboratory device.

  20. Communication devices for network-hopping communications and methods of network-hopping communications

    Science.gov (United States)

    Buttles, John W

    2013-04-23

    Wireless communication devices include a software-defined radio coupled to processing circuitry. The system controller is configured to execute computer programming code. Storage media is coupled to the system controller and includes computer programming code configured to cause the system controller to configure and reconfigure the software-defined radio to operate on each of a plurality of communication networks according to a selected sequence. Methods for communicating with a wireless device and methods of wireless network-hopping are also disclosed.

  1. MILITARY MULTI-HOP ROUTING PROTOCOL

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Military tactical network is one of the most important applications of ad hoc network. Currently the existing routing protocols are put forward based on the simple and universal network model which has the ability of multi-hop routing but cannot work efficiently in the special military applications. The narrow bandwidth and limited energy of the wireless network make general routing protocols seem to be more redundant.In order to satisfy military needs properly, this letter makes a detailed analysis of physical nodes and traffic distribution in military network, uses cross-layer design concept for reference, combines traffic characteristic of application layer with routing protocol design. It categorized routing problem as crucial routes and non-crucial routes which adopted separate maintenance methods. It not only realizes basic transmission function but also works efficiently. It is quite fit for military application.

  2. Direct current hopping conductance along DNA chain

    Institute of Scientific and Technical Information of China (English)

    Ma Song-Shan; Xu Hui; Liu Xiao-Liang; Li Ming-Jun

    2007-01-01

    This paper proposes a model of direct current(DC) electron hopping transport in DNA,in which DNA is considered as a binary one-dimensional disordered system.To quantitatively study the DC conductivity in DNA,it numerically calculates the DC conductivity of DNA chains with difierent parameter values.The result shows that the DC conductivity of DNA chain increases with the increase of temperature.And the conductivity of DNA chain is depended on the probability P.which represents the degree of compositional disorder in a DNA sequence to some extent.For P<0.5,the conductivity of DNA chain decreases with the increase of P,while for P≥0.5,the conductivity increases with the increase of p.The DC conductivity in DNA chain also varies with the change of the electric field,it presents non-Ohm's law conductivity characteristics.

  3. Capturing dynamic cation hopping in cubic pyrochlores

    Science.gov (United States)

    Brooks Hinojosa, Beverly; Asthagiri, Aravind; Nino, Juan C.

    2011-08-01

    In direct contrast to recent reports, density functional theory predicts that the most stable structure of Bi2Ti2O7 pyrochlore is a cubic Fd3¯m space group by accounting for atomic displacements. The displaced Bi occupies the 96g(x,x,z) Wyckoff position with six equivalent sites, which create multiple local minima. Using nudged elastic band method, the transition states of Bi cation hopping between equivalent minima were investigated and an energy barrier between 0.11 and 0.21 eV was determined. Energy barriers associated with the motion of Bi between equivalent sites within the 96g Wyckoff position suggest the presence of dielectric relaxation in Bi2Ti2O7.

  4. Bit-padding information guided channel hopping

    KAUST Repository

    Yang, Yuli

    2011-02-01

    In the context of multiple-input multiple-output (MIMO) communications, we propose a bit-padding information guided channel hopping (BP-IGCH) scheme which breaks the limitation that the number of transmit antennas has to be a power of two based on the IGCH concept. The proposed scheme prescribes different bit-lengths to be mapped onto the indices of the transmit antennas and then uses padding technique to avoid error propagation. Numerical results and comparisons, on both the capacity and the bit error rate performances, are provided and show the advantage of the proposed scheme. The BP-IGCH scheme not only offers lower complexity to realize the design flexibility, but also achieves better performance. © 2011 IEEE.

  5. Influence of iron impurities on defected graphene

    Energy Technology Data Exchange (ETDEWEB)

    Faccio, Ricardo; Pardo, Helena [Centro NanoMat, Cryssmat-Lab, DETEMA, Polo Tecnológico de Pando, Facultad de Química, Universidad de la República, Cno. Saravia s/n, CP 91000 Pando (Uruguay); Centro Interdisciplinario en Nanotecnología, Química y Física de Materiales, Espacio Interdisciplinario, Universidad de la República, Montevideo (Uruguay); Araújo-Moreira, Fernando M. [Materials and Devices Group, Department of Physics, Universidade Federal de São Carlos, SP 13565-905 (Brazil); Mombrú, Alvaro W., E-mail: amombru@fq.edu.uy [Centro NanoMat, Cryssmat-Lab, DETEMA, Polo Tecnológico de Pando, Facultad de Química, Universidad de la República, Cno. Saravia s/n, CP 91000 Pando (Uruguay); Centro Interdisciplinario en Nanotecnología, Química y Física de Materiales, Espacio Interdisciplinario, Universidad de la República, Montevideo (Uruguay)

    2015-03-01

    Highlights: • The interaction among a multivacancy graphene system and iron impurities is studied. • The studied iron impurities were single atom and tetrahedral and octahedral clusters. • DFT calculations using the VASP code were performed. • The embedding of Fe affects the structure and electronic behavior in the graphene. • Half metal or semimetal behavior can be obtained, depending on the Fe impurities. - Abstract: The aim of this work is to study the interaction of selected iron cluster impurities and a multivacancy graphene system, in terms of the structural distortion that the impurities cause as well as their magnetic response. While originally, the interaction has been limited to vacancies and isolated metallic atoms, in this case, we consider small iron clusters. This study was undertaken using Density Functional Theory (DFT) calculations. The influence of the iron impurities in the electronic structure of the vacant graphene system is discussed. The main conclusion of this work is that the presence of iron impurities acts lowering the magnetic signal due to the occurrence of spin pairing between carbon and iron, instead of enhancing the possible intrinsic carbon magnetism.

  6. Paramagnetic Attraction of Impurity-Helium Solids

    Science.gov (United States)

    Bernard, E. P.; Boltnev, R. E.; Khmelenko, V. V.; Lee, D. M.

    2003-01-01

    Impurity-helium solids are formed when a mixture of impurity and helium gases enters a volume of superfluid helium. Typical choices of impurity gas are hydrogen deuteride, deuterium, nitrogen, neon and argon, or a mixture of these. These solids consist of individual impurity atoms and molecules as well as clusters of impurity atoms and molecules covered with layers of solidified helium. The clusters have an imperfect crystalline structure and diameters ranging up to 90 angstroms, depending somewhat on the choice of impurity. Immediately following formation the clusters aggregate into loosely connected porous solids that are submerged in and completely permeated by the liquid helium. Im-He solids are extremely effective at stabilizing high concentrations of free radicals, which can be introduced by applying a high power RF dis- charge to the impurity gas mixture just before it strikes the super fluid helium. Average concentrations of 10(exp 19) nitrogen atoms/cc and 5 x 10(exp 18) deuterium atoms/cc can be achieved this way. It shows a typical sample formed from a mixture of atomic and molecular hydrogen and deuterium. It shows typical sample formed from atomic and molecular nitrogen. Much of the stability of Im-He solids is attributed to their very large surface area to volume ratio and their permeation by super fluid helium. Heat resulting from a chance meeting and recombination of free radicals is quickly dissipated by the super fluid helium instead of thermally promoting the diffusion of other nearby free radicals.

  7. Electronic structure and magnetic properties of dilute U impurities in metals

    Science.gov (United States)

    Mohanta, S. K.; Cottenier, S.; Mishra, S. N.

    2016-05-01

    The electronic structure and magnetic moment of dilute U impurity in metallic hosts have been calculated from first principles. The calculations have been performed within local density approximation of the density functional theory using Augmented plane wave+local orbital (APW+lo) technique, taking account of spin-orbit coupling and Coulomb correlation through LDA+U approach. We present here our results for the local density of states, magnetic moment and hyperfine field calculated for an isolated U impurity embedded in hosts with sp-, d- and f-type conduction electrons. The results of our systematic study provide a comprehensive insight on the pressure dependence of 5f local magnetism in metallic systems. The unpolarized local density of states (LDOS), analyzed within the frame work of Stoner model suggest the occurrence of local moment for U in sp-elements, noble metals and f-block hosts like La, Ce, Lu and Th. In contrast, U is predicted to be nonmagnetic in most transition metal hosts except in Sc, Ti, Y, Zr, and Hf consistent with the results obtained from spin polarized calculation. The spin and orbital magnetic moments of U computed within the frame of LDA+U formalism show a scaling behavior with lattice compression. We have also computed the spin and orbital hyperfine fields and a detail analysis has been carried out. The host dependent trends for the magnetic moment, hyperfine field and 5f occupation reflect pressure induced change of electronic structure with U valency changing from 3+ to 4+ under lattice compression. In addition, we have made a detailed analysis of the impurity induced host spin polarization suggesting qualitatively different roles of f-band electrons on moment stability. The results presented in this work would be helpful towards understanding magnetism and spin fluctuation in U based alloys.

  8. Impurity atoms on view in cuprates

    Directory of Open Access Journals (Sweden)

    J.C. Séamus Davis

    2002-04-01

    Full Text Available Impurity atoms in a material are usually viewed as a problem because they can result in non-ideal properties. However, they can sometimes be used to advantage when attempting to understand new materials. This is because the interactions of an impurity atom with the material reveal detailed information on the local electronic environment. In this paper we discuss scanning tunneling microscopy studies of the atomic-scale effects of individual Ni and Zn impurity atoms on the cuprate high critical temperature superconductors.

  9. Simulated impurity transport in LHD from MIST

    Energy Technology Data Exchange (ETDEWEB)

    Rice, J.E. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1998-05-01

    The impurity transport code MIST and atomic physics package LINES are used to calculate the time evolution of charge state density profiles, individual line emissivity profiles and total radiated power profiles for impurities in LHD plasmas. Three model LHD plasmas are considered; a high density, low temperature case, a low density, high temperature case and the initial LHD start-up plasma (500 kW ECH), using impurity transport coefficient profiles from Heliotron E. The elements oxygen, neon, scandium, iron, nickel and molybdenum are considered, both injected and in steady state. (author)

  10. Correlated hopping of bosonic atoms induced by optical lattices

    Energy Technology Data Exchange (ETDEWEB)

    Eckholt, Maria [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, Garching, D-85478 (Germany); Garcia-Ripoll, Juan Jose [Instituto de Fisica Fundamental, CSIC, c/Serrano 113b, Madrid E-28006 (Spain)], E-mail: maria.eckholt@mpq.mpg.de

    2009-09-15

    In this work, we analyze a particular setup with ultracold atoms trapped in state-dependent lattices. We show that any asymmetry in the contact interaction translates into one of two classes of correlated hopping. After deriving the effective lattice Hamiltonian for the atoms, we obtain analytically and numerically the different phases and quantum phase transitions. We find for weak correlated hopping both Mott insulators and charge density waves, while for stronger correlated hopping the system transitions into a pair superfluid. We demonstrate that this phase exists for a wide range of interaction asymmetries and has interesting correlation properties that differentiate it from an ordinary atomic Bose-Einstein condensate.

  11. Anomalous Localized Resonance Phenomena in the Nonmagnetic, Finite-Frequency Regime

    Directory of Open Access Journals (Sweden)

    Daniel Onofrei

    2016-01-01

    Full Text Available The phenomenon of anomalous localized resonance (ALR is observed at the interface between materials with positive and negative material parameters and is characterized by the fact that when a given source is placed near the interface, the electric and magnetic fields start to have very fast and large oscillations around the interface as the absorption in the materials becomes very small while they remain smooth and regular away from the interface. In this paper, we discuss the phenomenon of anomalous localized resonance (ALR in the context of an infinite slab of homogeneous, nonmagnetic material (μ=1 with permittivity ϵs=-1-iδ for some small loss δ≪1 surrounded by positive, nonmagnetic, homogeneous media. We explicitly characterize the limit value of the product between frequency and the width of slab beyond which the ALR phenomenon does not occur and analyze the situation when the phenomenon is observed. In addition, we also construct sources for which the ALR phenomenon never appears.

  12. Quantifying absolute spin polarization with non-magnetic contacts in FM/ n-GaAs heterostructures

    Science.gov (United States)

    Geppert, Chad; Wienkes, Lee; Christie, Kevin; Patel, Sahil; Palmstrøm, Chris; Crowell, Paul

    2014-03-01

    We report on a novel method of quantifying spin accumulation in Co2MnSi/ n-GaAs and Fe/ n-GaAs heterostructures using a non-magnetic probe. The presence of a non-equilibrium spin polarization generates a large electrostatic potential shift relative to the equilibrium state. This is due to the combination of (1) the parabolic (non-constant) density of states and (2) the population imbalance between the two spin sub-bands. We observe this shift as a Hanle effect in a non-local, non-magnetic semiconducting contact. Since this signal depends only on experimentally accessible parameters of the bulk semiconductor, its magnitude may be used to quantify the injected spin polarization in absolute terms. By comparison with the (smaller) spin-valve signal observed with a second ferromagnetic contact, we demonstrate that this electrostatic shift scales quadratically with spin polarization, dephases in the presence of both applied and hyperfine fields, and is observable to higher temperatures than traditional non-local measurements. Quantitative modeling allows extraction of absolute polarizations in excess of 50 % at low temperatures, and further indicates that this contribution constitutes a large fraction of the three-terminal signal observed in these devices. Supported by NSF DMR-1104951; by STARnet, a SRC program sponsored by MARCO and DARPA; and by the NSF MRSEC program.

  13. Kramers non-magnetic superconductivity in LnNiAsO superconductors.

    Science.gov (United States)

    Li, Yuke; Luo, Yongkang; Li, Lin; Chen, Bin; Xu, Xiaofeng; Dai, Jianhui; Yang, Xiaojun; Zhang, Li; Cao, Guanghan; Xu, Zhu-an

    2014-10-22

    We investigated a series of nickel-based oxyarsenides LnNiAsO (Ln=La, Ce, Pr, Nd, Sm) compounds. CeNiAsO undergoes two successive anti-ferromagnetic transitions at TN1=9.3 K and TN2=7.3 K; SmNiAsO becomes an anti-ferromagnet below TN≃3.5 K; NdNiAsO keeps paramagnetic down to 2 K but orders anti-ferromagnetically below TN≃1.3 K. Superconductivity was observed only in Kramers non-magnetic LaNiAsO and PrNiAsO with Tc=2.7 K and 0.93 K, respectively. The superconductivity of PrNiAsO is further studied by upper critical field and specific heat measurements, which reveal that PrNiAsO is a weakly coupled Kramers non-magnetic superconductor. Our work confirms that the nickel-based oxyarsenide superconductors are substantially different in mechanism to iron-based ones, and are likely to be described by the conventional superconductivity theory.

  14. Magnetism at the Interface of Magnetic Oxide and Nonmagnetic Semiconductor Quantum Dots.

    Science.gov (United States)

    Saha, Avijit; Viswanatha, Ranjani

    2017-03-28

    Engineering interfaces specifically in quantum dot (QD) heterostructures provide several prospects for developing multifunctional building block materials. Precise control over internal structure by chemical synthesis offers a combination of different properties in QDs and allows us to study their fundamental properties, depending on their structure. Herein, we studied the interface of magnetic/nonmagnetic Fe3O4/CdS QD heterostructures. In this work, we demonstrate the decrease in the size of the magnetic core due to annealing at high temperature by the decrease in saturation magnetization and blocking temperature. Furthermore, surprisingly, in a prominently optically active and magnetically inactive material such as CdS, we observe the presence of substantial exchange bias in spite of the nonmagnetic nature of CdS QDs. The presence of exchange bias was proven by the increase in magnetic anisotropy as well as the presence of exchange bias field (HE) during the field-cooled magnetic measurements. This exchange coupling was eventually traced to the in situ formation of a thin antiferromagnetic FeS layer at the interface. This is verified by the study of Fe local structure using X-ray absorption fine structure spectroscopy, demonstrating the importance of interface engineering in QDs.

  15. Component masses of young, wide, non-magnetic white dwarf binaries in the SDSS DR7

    CERN Document Server

    Baxter, R B; Parker, Q A; Casewell, S L; Lodieu, N; Burleigh, M R; Lawrie, K A; Kulebi, B; Koester, D; Holland, B R

    2014-01-01

    We present a spectroscopic component analysis of 18 candidate young, wide, non-magnetic, double-degenerate binaries identified from a search of the Sloan Digital Sky Survey Data Release 7 (DR7). All but two pairings are likely to be physical systems. We show SDSS J084952.47+471247.7 + SDSS J084952.87+471249.4 to be a wide DA+DB binary, only the second identified to date. Combining our measurements for the components of 16 new binaries with results for three similar, previously known systems within the DR7, we have constructed a mass distribution for the largest sample to date (38) of white dwarfs in young, wide, non-magnetic, double-degenerate pairings. This is broadly similar in form to that of the isolated field population with a substantial peak around M~0.6 Msun. We identify an excess of ultra-massive white dwarfs and attribute this to the primordial separation distribution of their progenitor systems peaking at relatively larger values and the greater expansion of their binary orbits during the final sta...

  16. Let Me Blow Your Mind: Hip Hop Feminist Futures in Theory and Praxis

    Science.gov (United States)

    Lindsey, Treva B.

    2015-01-01

    This essay brings together key theoretical interventions in hip-hop feminism to explore the continued, but undervalued, significance of hip-hop feminism in urban education. More specifically, the essay challenges narrow conceptualizations of the "hip hop subject" as Black and male by using hip-hop feminist theory to incorporate the lived…

  17. Characterization of hop pectins shows the presence of an arabinogalactan-protein

    NARCIS (Netherlands)

    Oosterveld, A.; Voragen, A.G.J.; Schols, H.A.

    2002-01-01

    Hop pectins were extracted from spent hops using acid extraction conditions and were characterized chemically. The acid extraction of spent hops resulted in a yield of 2°containing 59 f polysaccharides. The hop pectins under investigation had a relatively high molecular weight and an intrinsic visco

  18. Let Me Blow Your Mind: Hip Hop Feminist Futures in Theory and Praxis

    Science.gov (United States)

    Lindsey, Treva B.

    2015-01-01

    This essay brings together key theoretical interventions in hip-hop feminism to explore the continued, but undervalued, significance of hip-hop feminism in urban education. More specifically, the essay challenges narrow conceptualizations of the "hip hop subject" as Black and male by using hip-hop feminist theory to incorporate the lived…

  19. Mic Power? Connections and the hip hop nation in Kampala, Uganda

    DEFF Research Database (Denmark)

    Schneidermann, Nanna

    2014-01-01

    Hip hop culture has been celebrated in the media and scholarship as a universal youth language, part of a global hip hop nation, and a type of counter-public. This article examines the everyday meanings and practices of hip hop among hip hop activists in Kampala, Uganda, specifically within the B...

  20. Glycolic acid physical properties and impurities assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Pickenheim, B. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hay, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); BIBLER, N. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-08-09

    This document has been revised to add analytical data for fresh, 1 year old, and 4 year old glycolic acid as recommended in Revision 2 of this document. This was needed to understand the concentration of formaldehyde and methoxyacetic acid, impurities present in the glycolic acid used in Savannah River National Laboratory (SRNL) experiments. Based on this information, the concentration of these impurities did not change during storage. These impurities were in the glycolic acid used in the testing included in this report and in subsequent testing using DuPont (now called Chemours) supplied Technical Grade 70 wt% glycolic acid. However, these impurities were not reported in the first two versions of this report. The Defense Waste Processing Facility (DWPF) is planning to implement a nitric-glycolic acid flowsheets to increase attainment to meet closure commitment dates during Sludge Batch 9. In fiscal year 2009, SRNL was requested to determine the physical properties of formic and glycolic acid blends.

  1. Effects of impurity location on the impurity bands and their spectral densities in quantum wells

    Science.gov (United States)

    Gold, A.; Ghazali, A.; Serre, J.

    1989-09-01

    The electronic density of states and the spectral density of quantum wells are calculated as functions of the impurity position zi. A multiple-scattering method which accounts for the formation of impurity bands is used. The study of the spectral densities provides us with the behavior of the averaged wave functions of the ground- and excited-state impurity bands in the k space. We demonstrate that our approach can be used to study hybridization effects between different bands.

  2. Invariance of the magnetic behavior and AMI in ferromagnetic biphase films with distinct non-magnetic metallic spacers

    Energy Technology Data Exchange (ETDEWEB)

    Silva, E.F. [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Gamino, M. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Instituto de Física, Universidade Federal do Rio Grande de Sul, 91501-970 Porto Alegre, RS (Brazil); Andrade, A.M.H. de [Instituto de Física, Universidade Federal do Rio Grande de Sul, 91501-970 Porto Alegre, RS (Brazil); Vázquez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain); Correa, M.A. [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Bohn, F., E-mail: felipebohn@fisica.ufrn.br [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil)

    2017-02-01

    We investigate the quasi-static magnetic, magnetotransport, and dynamic magnetic properties in ferromagnetic biphase films with distinct non-magnetic metallic spacer layers. We observe that the nature of the non-magnetic metallic spacer material does not have significant influence on the overall biphase magnetic behavior, and, consequently, on the magnetotransport and dynamic magnetic responses. We focus on the magnetoimpedance effect and verify that the films present asymmetric magnetoimpedance effect. Moreover, we explore the possibility of tuning the linear region of the magnetoimpedance curves around zero magnetic field by varying the probe current frequency in order to achieve higher sensitivity values. The invariance of the magnetic behavior and the asymmetric magnetoimpedance effect in ferromagnetic biphase films with distinct non-magnetic metallic spacers place them as promising candidates for probe element and open possibilities to the development of lower-cost high sensitivity linear magnetic field sensor devices.

  3. Invariance of the magnetic behavior and AMI in ferromagnetic biphase films with distinct non-magnetic metallic spacers

    Science.gov (United States)

    Silva, E. F.; Gamino, M.; Andrade, A. M. H. de; Vázquez, M.; Correa, M. A.; Bohn, F.

    2017-02-01

    We investigate the quasi-static magnetic, magnetotransport, and dynamic magnetic properties in ferromagnetic biphase films with distinct non-magnetic metallic spacer layers. We observe that the nature of the non-magnetic metallic spacer material does not have significant influence on the overall biphase magnetic behavior, and, consequently, on the magnetotransport and dynamic magnetic responses. We focus on the magnetoimpedance effect and verify that the films present asymmetric magnetoimpedance effect. Moreover, we explore the possibility of tuning the linear region of the magnetoimpedance curves around zero magnetic field by varying the probe current frequency in order to achieve higher sensitivity values. The invariance of the magnetic behavior and the asymmetric magnetoimpedance effect in ferromagnetic biphase films with distinct non-magnetic metallic spacers place them as promising candidates for probe element and open possibilities to the development of lower-cost high sensitivity linear magnetic field sensor devices.

  4. DETERMINATION OF IMPURITY ELEMENTS IN ALUMINIUM

    Institute of Scientific and Technical Information of China (English)

    侯小琳; 张永保

    1994-01-01

    Twenty five impurity elements in aluminium applied as reactor material are determined.Titanium and nickel are determined with epithermal neutron activation analysis(NAA),magnesium and silicon by inductance coupling plasma emission spectra(ICP),other elements by thermal NAA.The fission coefficient of uranium is given by an experiment,the interferences of uranium to Ce,Nd,Mo,Zr,La,Sm are subtracted.The detection limits of these methods to all of impurity elements in aluminium are calculated.

  5. Quantum critical points in quantum impurity systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Jung [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany); Bulla, Ralf [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany)]. E-mail: bulla@cpfs.mpg.de

    2005-04-30

    The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.

  6. Quantum critical points in quantum impurity systems

    Science.gov (United States)

    Lee, Hyun Jung; Bulla, Ralf

    2005-04-01

    The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.

  7. Parametrically Driven Nonlinear Oscillators with an Impurity

    Institute of Scientific and Technical Information of China (English)

    张卓; 唐翌

    2002-01-01

    By virtue of the method of multiple scales, we study a chain of parametrically driven nonlinear oscillators with a mass impurity. An equation is presented to describe the nonlinear wave of small amplitude in the chain.In our derivation, the equation is applicable to any eigenmode of coupled pendulum. Our result shows that a nonpropagation soliton emerges as the lowest or highest eigenmode of coupled pendulum is excited, and the impurity tends to pin the nonpropagation soliton excitation.

  8. Effects of helium impurities on superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Selle, J.E.

    1977-07-01

    A review of the literature on the effects of helium impurities on superalloys at elevated temperatures was undertaken. The actual effects of these impurities vary depending on the alloy, composition of the gas atmosphere, and temperature. In general, exposure in helium produces significant but not catastrophic changes in the structure and properties of the alloys. The effects of these treatments on the structure, creep, fatigue, and mechanical properties of the various alloys are reviewed and discussed. Suggestions for future work are presented.

  9. Hamiltonian-based impurity solver for nonequilibrium dynamical mean-field theory

    Science.gov (United States)

    Gramsch, Christian; Balzer, Karsten; Eckstein, Martin; Kollar, Marcus

    2013-12-01

    We derive an exact mapping from the action of nonequilibrium dynamical mean-field theory (DMFT) to a single-impurity Anderson model (SIAM) with time-dependent parameters, which can be solved numerically by exact diagonalization. The representability of the nonequilibrium DMFT action by a SIAM is established as a rather general property of nonequilibrium Green functions. We also obtain the nonequilibrium DMFT equations using the cavity method alone. We show how to numerically obtain the SIAM parameters using Cholesky or eigenvector matrix decompositions. As an application, we use a Krylov-based time propagation method to investigate the Hubbard model in which the hopping is switched on, starting from the atomic limit. Possible future developments are discussed.

  10. Local chemistry of Al and P impurities in silica

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Stokbro, Kurt

    2000-01-01

    The local structure around Al and P impurities in silica is investigated using density-functional theory. Two distinct cases are considered: impurities substituting for a Si atom in alpha quartz, and impurities implanted in a stoichiometric alpha-quartz crystal. Both impurity elements are found t...

  11. Determinants of Job Hopping Experience among Private and Public ...

    African Journals Online (AJOL)

    Determinants of Job Hopping Experience among Private and Public Sector ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL ... This study investigated perceived organizational justice, job stress and job ...

  12. Hip Hop Dance Experience Linked to Sociocognitive Ability

    National Research Council Canada - National Science Library

    Justin W Bonny; Jenna C Lindberg; Marc C Pacampara

    2017-01-01

    .... In the present study, we examined whether experience in a different activity, hip hop dance, is also linked to cognitive abilities connected with STEM skills as well as social cognition ability...

  13. Correlated barrier hopping of CuO nanoparticles

    Science.gov (United States)

    Koshy, Jiji; Soosen, Samuel. M.; Chandran, Anoop; George, K. C.

    2015-12-01

    The ac conduction mechanism in copper oxide nanoparticles with 8 nm size, synthesized by a precipitation method was studied by analyzing ac conductivity in the frequency range of 50 Hz-1 MHz and in the temperature range of 373-573 K. X-ray diffraction and transmission electron microscopy (TEM) were employed for the structural and morphological characterization of CuO nanoparticles. The experimental and theoretical investigations suggested that the ac conduction mechanism in CuO nanoparticles can be successfully explained by a correlated barrier hopping model, which provided reasonable values for the maximum barrier height and characteristic relaxation time. It was also found that bipolaron hopping become prominent up to a particular temperature and beyond that single polaron hopping predominates. Physical parameters such as hopping distance and density of defect states were also calculated. Photoluminescence studies confirm the presence of a surface defect in CuO nanoparticles.

  14. Hopping trajectory optimization for surface exploration on small bodies

    Science.gov (United States)

    Liu, Yanjie; Zhu, Shengying; Cui, Pingyuan; Yu, Zhengshi; Zong, Hua

    2017-07-01

    Surface exploration is an important way to improve the understanding of small bodies. Considering the irregular and weak gravity field near a small body, the movement of the surface explorer is generally achieved by hopping. In this paper, a guidance algorithm method based on convex optimization approach for pinpoint hopping movement on a small body is developed in order to improve the stability and accuracy of surface exploration. We formulate a fuel-optimal control problem for the single pinpoint hopping and convert it into a second-order cone programming (SOCP) problem which can be solved effectively by primal-dual-interior points method. A multi-hopping scenario is also proposed for the long-distance transfer. To certificate the performance of the proposed guidance algorithm, a full set of simulations are conducted and the effectiveness are analyzed.

  15. Potential African Substitutes for Hops in Tropical Beer Brewing

    African Journals Online (AJOL)

    These values however decreased, the longer the storage period. Losses in bitterness ... Key words: Hops, Resins, Essential Oils, Bitterness level. ... tight transparent glass bottle and then ... measured. ..... contact with oxygen and also the rate.

  16. Leg exoskeleton reduces the metabolic cost of human hopping.

    Science.gov (United States)

    Grabowski, Alena M; Herr, Hugh M

    2009-09-01

    During bouncing gaits such as hopping and running, leg muscles generate force to enable elastic energy storage and return primarily from tendons and, thus, demand metabolic energy. In an effort to reduce metabolic demand, we designed two elastic leg exoskeletons that act in parallel with the wearer's legs; one exoskeleton consisted of a multiple leaf (MLE) and the other of a single leaf (SLE) set of fiberglass springs. We hypothesized that hoppers, hopping on both legs, would adjust their leg stiffness while wearing an exoskeleton so that the combination of the hopper and exoskeleton would behave as a linear spring-mass system with the same total stiffness as during normal hopping. We also hypothesized that decreased leg force generation while wearing an exoskeleton would reduce the metabolic power required for hopping. Nine subjects hopped in place at 2.0, 2.2, 2.4, and 2.6 Hz with and without an exoskeleton while we measured ground reaction forces, exoskeletal compression, and metabolic rates. While wearing an exoskeleton, hoppers adjusted their leg stiffness to maintain linear spring-mass mechanics and a total stiffness similar to normal hopping. Without accounting for the added weight of each exoskeleton, wearing the MLE reduced net metabolic power by an average of 6% and wearing the SLE reduced net metabolic power by an average of 24% compared with hopping normally at frequencies between 2.0 and 2.6 Hz. Thus, when hoppers used external parallel springs, they likely decreased the mechanical work performed by the legs and substantially reduced metabolic demand compared with hopping without wearing an exoskeleton.

  17. Transport of hop aroma compounds across Caco-2 monolayers

    OpenAIRE

    Heinlein, A.; Metzger, M.; Walles, H.; Buettner, A.

    2014-01-01

    Although being reported and used as a sedative remedy for several years, the bioactive principle of hop preparations is still not decisively clarified. Understanding absorption and transformation processes of potential physiologically active constituents is essential to evaluate the likeliness of biological effects on humans. Therefore, single hop aroma compounds as well as digestive transformation products thereof have been investigated in view of their human intestinal absorption, applying ...

  18. Role of correlated hopping in mixed valence phenomena

    Indian Academy of Sciences (India)

    N K Ghosh; S K Bhowmick; N S Mondal

    2011-01-01

    Role of correlated hopping is studied using extended Falicov–Kimball model in a small cluster. A discontinuous insulator-to-metal transition is observed at a critical -level energy. Transition is sharper for larger correlated hopping. In the specific heat curves a two-peak structure consisting of a sharp peak followed by a Schottky-type broad peak is exhibited. In a limited parameter region, some heavy-fermion like characteristics have been observed

  19. Low Power Multi-Hop Networking Analysis in Intelligent Environments.

    Science.gov (United States)

    Etxaniz, Josu; Aranguren, Gerardo

    2017-05-19

    Intelligent systems are driven by the latest technological advances in many different areas such as sensing, embedded systems, wireless communications or context recognition. This paper focuses on some of those areas. Concretely, the paper deals with wireless communications issues in embedded systems. More precisely, the paper combines the multi-hop networking with Bluetooth technology and a quality of service (QoS) metric, the latency. Bluetooth is a radio license-free worldwide communication standard that makes low power multi-hop wireless networking available. It establishes piconets (point-to-point and point-to-multipoint links) and scatternets (multi-hop networks). As a result, many Bluetooth nodes can be interconnected to set up ambient intelligent networks. Then, this paper presents the results of the investigation on multi-hop latency with park and sniff Bluetooth low power modes conducted over the hardware test bench previously implemented. In addition, the empirical models to estimate the latency of multi-hop communications over Bluetooth Asynchronous Connectionless Links (ACL) in park and sniff mode are given. The designers of devices and networks for intelligent systems will benefit from the estimation of the latency in Bluetooth multi-hop communications that the models provide.

  20. Hip Hop Syllabus: AME/MUS 303 Hip Hop: Art, Culture, and Politics

    Directory of Open Access Journals (Sweden)

    Sarah Hentges

    2013-10-01

    Full Text Available This syllabus represents a course taught online through the University of Maine at Augusta in the fall of 2011 (and every otheryear thereafter. Critical pedagogy can be a challenge in any classroom, and the challenges in an online classroom are compounded. However, the subject matter and approach of Hip Hop can be a powerful tool in teaching students critical thinking skills as well in laying a foundation for interdisciplinary and intersectional theory; here these elements are represented through curriculum—the themes, texts, contexts,approaches, structure, and assignments.

  1. Accurate water maser positions from HOPS

    CERN Document Server

    Walsh, Andrew J; Longmore, Steven N; Breen, Shari L; Green, James A; Harvey-Smith, Lisa; Jordan, Christopher H; Macpherson, Christopher

    2014-01-01

    We report on high spatial resolution water maser observations, using the Australia Telescope Compact Array, towards water maser sites previously identified in the H2O southern Galactic Plane Survey (HOPS). Of the 540 masers identified in the single-dish observations of Walsh et al. (2011), we detect emission in all but 31 fields. We report on 2790 spectral features (maser spots), with brightnesses ranging from 0.06 Jy to 576Jy and with velocities ranging from -238.5 to +300.5km/s. These spectral features are grouped into 631 maser sites. We have compared the positions of these sites to the literature to associate the sites with astrophysical objects. We identify 433 (69 per cent) with star formation, 121 (19 per cent) with evolved stars and 77 (12 per cent) as unknown. We find that maser sites associated with evolved stars tend to have more maser spots and have smaller angular sizes than those associated with star formation. We present evidence that maser sites associated with evolved stars show an increased ...

  2. Fast Hopping Frequency Generation in Digital CMOS

    CERN Document Server

    Farazian, Mohammad; Gudem, Prasad S

    2013-01-01

    Overcoming the agility limitations of conventional frequency synthesizers in multi-band OFDM ultra wideband is a key research goal in digital technology. This volume outlines a frequency plan that can generate all the required frequencies from a single fixed frequency, able to implement center frequencies with no more than two levels of SSB mixing. It recognizes the need for future synthesizers to bypass on-chip inductors and operate at low voltages to enable the increased integration and efficiency of networked appliances. The author examines in depth the architecture of the dividers that generate the necessary frequencies from a single base frequency and are capable of establishing a fractional division ratio.   Presenting the first CMOS inductorless single PLL 14-band frequency synthesizer for MB-OFDMUWB makes this volume a key addition to the literature, and with the synthesizer capable of arbitrary band-hopping in less than two nanoseconds, it operates well within the desired range on a 1.2-volt power s...

  3. Impurity radiation in DEMO systems modelling

    Energy Technology Data Exchange (ETDEWEB)

    Lux, H., E-mail: Hanni.Lux@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kemp, R.; Ward, D.J. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Sertoli, M. [Max-Planck-Institut für Plasma Physik, D-85748 Garching (Germany)

    2015-12-15

    Highlights: • Solving the exhaust problem is crucial for DEMO. • Here, we discuss the new impurity radiation model in the systems code PROCESS. • Furthermore, we assess its effect on DEMO design. • More appropriate scalings will significantly enhance predictions for DEMO. • The controllability of highly radiative scenarios remains to be shown. - Abstract: For fusion reactors with ITER divertor technology, it will be imperative to significantly reduce the heat flux into the divertor e.g. by seeded impurity radiation. This has to be done without affecting the accessibility of a high performance scenario. To assess the implications of seeded plasma impurities on DEMO design, we have developed an impurity radiation model for radiation inside the separatrix. Evaluating the validity of our model, we find the assumption of a local ionisation equilibrium to be appropriate for our purposes and the assumption of flat impurity profiles – even though not satisfactory – to represent the best currently possible. Benchmarking our model against other codes highlights the need to use up to date atomic loss function data. From the impurity radiation perspective, the main uncertainties in current DEMO design stem from the lack of confinement and L-H-threshold scalings that can be robustly extrapolated to highly radiative DEMO scenarios as well as the lack of appropriate models for the power flow from the separatrix into the divertor that include radiation in the scrape off layer. Despite these uncertainties in the model we can exclude that significant fuel dilution through seeded impurities (with Z ≥ Z{sub Ar}) will be an issue for DEMO, but the controllability of highly radiative scenarios still needs to be coherently shown.

  4. Magnetic reversal in iron thin films interspersed with non-magnetic pinning sites

    Energy Technology Data Exchange (ETDEWEB)

    Nau, Stefan; Wiedwald, Ulf; Wiedemann, Stefan; Plettl, Alfred; Ziemann, Paul [Institut fuer Festkoerperphysik, Universitaet Ulm (Germany)

    2010-07-01

    Magnetic switching of continuous iron thin films is tailored by structuring a periodic array of nonmagnetic holes acting as pinning centers for domain walls. Contrary to common lithographically prepared antidots, nanostructures are prepared by deposition of densely packed monolayers of polystyrene (PS) spheres on silicon and silicon nitride substrates. Isotropic plasma etching leads to adjustable PS diameters between 20% and 80% of the initial value while conserving the particle spacing. The influence on the magnetic reversal process is studied as a function of diameter and distance of the PS spheres. Iron films are deposited by pulsed laser deposition. Antidot arrays of 100 nm period lead to up to 15 times increased in-plane coercive fields at 300 K, depending on dot diameters and film thicknesses. The magnetic reversal is imaged by scanning transmission x-ray microscopy accompanied by micromagnetic simulations in order to understand domain nucleation and propagation in varying external fields.

  5. Increasing energy relaxation time of superconducting qubits with nonmagnetic infrared filter and shield

    Science.gov (United States)

    Yuhao, Liu; Mengmeng, Li; Dong, Lan; Guangming, Xue; Xinsheng, Tan; Haifeng, Yu; Yang, Yu

    2016-05-01

    One of the primary origins of the energy relaxation in superconducting qubits is the quasiparticle loss. The quasiparticles can be excited remarkably by infrared radiation. In order to minimize the density of quasiparticle and increase the qubit relaxation time, we design and fabricate the infrared filter and shield for superconducting qubits. In comparison with previous filters and shields, a nonmagnetic dielectric is used as the infrared absorbing material, greatly suppressing the background magnetic fluctuations. The filters can be made to impedance-match with other microwave devices. Using the as-fabricated infrared filter and shield, we increased the relaxation time of a transmon qubit from 519 ns to 1125 ns. Project supported by the National Natural Science Foundation of China (Grant Nos. 91321310, 11274156, 11474152, 11474153, 61521001, and 11504165) and the State Key Program for Basic Research of China (Grant Nos. 2011CB922104 and 2011CBA00205).

  6. Theoretical study of optical conductivity of graphene with magnetic and nonmagnetic adatoms

    Science.gov (United States)

    Majidi, Muhammad Aziz; Siregar, Syahril; Rusydi, Andrivo

    2014-11-01

    We present a theoretical study of the optical conductivity of graphene with magnetic and nonmagnetic adatoms. First, by introducing an alternating potential in a pure graphene, we demonstrate a gap formation in the density of states and the corresponding optical conductivity. We highlight the distinction between such a gap formation and the so-called Pauli blocking effect. Next, we apply this idea to graphene with adatoms by introducing magnetic interactions between the carrier spins and the spins of the adatoms. Exploring various possible ground-state spin configurations of the adatoms, we find that the antiferromagnetic configuration yields the lowest total electronic energy and is the only configuration that forms a gap. Furthermore, we analyze four different circumstances leading to similar gaplike structures and propose a means to interpret the magneticity and the possible orderings of the adatoms on graphene solely from the optical conductivity data. We apply this analysis to the recently reported experimental data of oxygenated graphene.

  7. Spin-dependent tunneling time in periodic diluted-magnetic-semiconductor/nonmagnetic-barrier superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ping-Fan; Guo, Yong, E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

    2016-02-01

    We investigate the tunneling time (dwell time) in periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB) superlattices subjected to an external magnetic field. It is found that spin-dependent resonant bands form in the spectra of dwell time, which can be effectively manipulated by not only the external magnetic field but also the geometric parameters of the system. Moreover, an intuitive semiclassical delay is defined to illustrate the behavior of the dwell time, and the former one is shown to be the result of “smoothing out” the latter one. We also find that the dwell time in diluted-magnetic-semiconductor/semiconductor superlattices behaves surprisingly different from the DMS/NB case, especially for spin-down electrons.

  8. Spin-Selective Electron Quantum Transport in Nonmagnetic MgZnO/ZnO Heterostructures.

    Science.gov (United States)

    Maryenko, D; Falson, J; Bahramy, M S; Dmitriev, I A; Kozuka, Y; Tsukazaki, A; Kawasaki, M

    2015-11-06

    We report magnetotransport measurements on a high-mobility two-dimensional electron system at the nonmagnetic MgZnO/ZnO heterointerface showing distinct behavior for electrons with spin-up and spin-down orientations. The low-field Shubnikov-de Haas oscillations manifest alternating resistance peak heights which can be attributed to distinct scattering rates for different spin orientations. The tilt-field measurements at a half-integer filling factor reveal that the majority spins show usual diffusive behavior, i.e., peaks with the magnitude proportional to the index of the Landau level at the Fermi energy. By contrast, the minority spins develop "plateaus" with the magnitude of dissipative resistivity that is fairly independent of the Landau level index and is of the order of the zero-field resistivity.

  9. Spin-orbit-induced longitudinal spin-polarized currents in nonmagnetic solids

    Science.gov (United States)

    Wimmer, S.; Seemann, M.; Chadova, K.; Ködderitzsch, D.; Ebert, H.

    2015-07-01

    For certain nonmagnetic solids with low symmetry the occurrence of spin-polarized longitudinal currents is predicted. These arise due to an interplay of spin-orbit interaction and the particular crystal symmetry. This result is derived using a group-theoretical scheme that allows investigating the symmetry properties of any linear response tensor relevant to the field of spintronics. For the spin conductivity tensor it is shown that only the magnetic Laue group has to be considered in this context. Within the introduced general scheme also the spin Hall and additional related transverse effects emerge without making reference to the two-current model. Numerical studies confirm these findings and demonstrate for (Au1-xPtx)4Sc that the longitudinal spin conductivity may be on the same order of magnitude as the conventional transverse one. The presented formalism only relies on the magnetic space group and therefore is universally applicable to any type of magnetic order.

  10. Affine nonmagnetic transformation optics and its application to a practical bending adapter design

    CERN Document Server

    Xu, Hongyi; Yu, Tianyuan; Barbastathis, George; Sun, Handong

    2011-01-01

    One of the bottlenecks that limit the transition of transformation-optics devices from concepts to practical use is the nonunit magnetic permeability generally required from a mathematical transformation. Simple renormalization of permeability, as used in many previous designs and experiments, introduces impedance mismatch and thus degrades the functional photonic performance. Here we propose an area-preserving affine coordinate transformation as a general method to solve this problem. Ideal transformation-optics functions can be preserved while nonmagnetism is achieved. As a specific example, we illustrate how to apply this affine method into the design of a two-dimensional electromagnetic beam bending adapter. Concerns related to fabrication, such as anisotropy degree and bending angles, are fully discussed. Our study is a significant step toward practical use of ideal transformation optics devices that can be implemented directly with existing dielectric materials.

  11. Ferromagnetic/Nonmagnetic Nanostructures for the Electrical Measurement of the Spin Hall Effect.

    Science.gov (United States)

    Pham, Van Tuong; Vila, Laurent; Zahnd, Gilles; Marty, Alain; Savero-Torres, Williams; Jamet, Matthieu; Attané, Jean-Philippe

    2016-11-09

    Spin-orbitronics is based on the ability of spin-orbit interactions to achieve the conversion between charge currents and pure spin currents. As the precise evaluation of the conversion efficiency becomes a crucial issue, the need for straightforward ways to observe this conversion has emerged as one of the main challenges in spintronics. Here, we propose a simple device, akin to the ferromagnetic/nonmagnetic bilayers used in most spin-orbit torques experiments, and consisting of a spin Hall effect wire connected to two transverse ferromagnetic electrodes. We show that this system allows probing electrically the direct and inverse conversion in a spin Hall effect system and measuring both the spin Hall angle and the spin diffusion length. By applying this method to several spin Hall effect materials (Pt, Pd, Au, Ta, W), we show that it represents a promising tool for the metrology of spin-orbit materials.

  12. Pseudo-hcp nonmagnetic intermediate layer for granular media with high perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Atsushi [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Saito, Shin [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Itagaki, Norikazu [Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Takahashi, Migaku [New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2008-01-07

    Materials with the hexagonal close-packed structure (hcp) and the face-centred-cubic structure with stacking faults (pseudo-hcp) are examined for the nonmagnetic intermediate layer (NMIL) in order to suppress variant growth of magnetic grains for granular-type perpendicular recording media. Judging from the analysis of the epitaxial growth of Co-based magnetic grains, it has been found that a lattice misfit between NMIL and magnetic grain of less than 6% and a spreading coefficient of wettability of magnetic grain on NMIL of greater than 0.3 J m{sup -3} are required for the recording layer to have high perpendicular magnetic anisotropy energy. (fast track communication)

  13. Non-magnetic photospheric bright points in 3D simulations of the solar atmosphere

    Science.gov (United States)

    Calvo, F.; Steiner, O.; Freytag, B.

    2016-11-01

    Context. Small-scale bright features in the photosphere of the Sun, such as faculae or G-band bright points, appear in connection with small-scale magnetic flux concentrations. Aims: Here we report on a new class of photospheric bright points that are free of magnetic fields. So far, these are visible in numerical simulations only. We explore conditions required for their observational detection. Methods: Numerical radiation (magneto-)hydrodynamic simulations of the near-surface layers of the Sun were carried out. The magnetic field-free simulations show tiny bright points, reminiscent of magnetic bright points, only smaller. A simple toy model for these non-magnetic bright points (nMBPs) was established that serves as a base for the development of an algorithm for their automatic detection. Basic physical properties of 357 detected nMBPs were extracted and statistically evaluated. We produced synthetic intensity maps that mimic observations with various solar telescopes to obtain hints on their detectability. Results: The nMBPs of the simulations show a mean bolometric intensity contrast with respect to their intergranular surroundings of approximately 20%, a size of 60-80 km, and the isosurface of optical depth unity is at their location depressed by 80-100 km. They are caused by swirling downdrafts that provide, by means of the centripetal force, the necessary pressure gradient for the formation of a funnel of reduced mass density that reaches from the subsurface layers into the photosphere. Similar, frequently occurring funnels that do not reach into the photosphere, do not produce bright points. Conclusions: Non-magnetic bright points are the observable manifestation of vertically extending vortices (vortex tubes) in the photosphere. The resolving power of 4-m-class telescopes, such as the DKIST, is needed for an unambiguous detection of them. The movie associated to Fig. 1 is available at http://www.aanda.org

  14. Efros-Shklovskii type variable range hopping conduction and magnetoresistance in p-type CuGa3Te5

    Science.gov (United States)

    Wasim, S. M.; Essaleh, L.; Marín, G.; Rincón, C.; Amhil, S.; Galibert, J.

    2017-07-01

    Variable range hopping conduction of Efros and Shklovskii type when a Coulomb gap appears at the Fermi level due to repulsive interaction of the holes, is observed in two different temperature regions in the ordered defect compound CuGa3Te5. Since this type of electrical conduction appears over a very wide temperature range between 4 and 150 K, not reported before in elemental II-VI, and I-III-VI2 compound semiconductors, three different methods were employed to analyze the data to confirm this behavior. This is also supported from the study of the variation of impurity band hole mobility with temperature. Other hopping parameters are estimated. The logarithmic variation of the positive magnetoresistance at different temperatures in the two regions varies as B2 and B1/5 above and below the critical field Bc, that separates the low and high magnetic field regions. This is in complete agreement with the theory of Efros and Shklovskii. The temperature dependence of the corresponding slope as T- 3/2 and T- 3/5 is also consistent with the proposed models.

  15. Simulating W Impurity Transport in Tokamaks

    Science.gov (United States)

    Younkin, Timothy R.; Green, David L.; Lasa, Ane; Canik, John M.; Wirth, Brian D.

    2016-10-01

    The extreme heat and charged particle flux to plasma facing materials in magnetically confined fusion devices has motivated Tungsten experiments such as the ``W-Ring'' experiment on the DIII-D tokamak to investigate W divertor viability. In this domain, the transport of W impurities from their tile locations to other first-wall tiles is highly relevant to material lifetimes and tokamak operation. Here we present initial results from a simulation of this W transport. Given that sputtered impurities may experience prompt redeposition near the divertor strikepoint, or migrate far from its origin to the midplane, there is a need to track the global, 3-D, impurity redistribution. This is done by directly integrating the 6-D Lorentz equation of motion (plus thermal gradient terms and relevant Monte-Carlo operators) for the impurity ions and neutrals under background plasma parameters determined by the SOLPS edge plasma code. The geometric details of the plasma facing components are represented to a fidelity sufficient to examine the global impurity migration trends with initial work also presented on advanced surface meshing capabilities targeting high fidelity simulation. This work is supported by U.S. DOE Office of Science SciDAC project on plasma-surface interactions under US DOE contract DE-AC05-00OR22725.

  16. Gettering of metal impurities in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schroeter, W.; Spiecker, E.; Apel, M. [Universitaet Goettingen (Germany)

    1995-08-01

    Gettering means the removal of metallic impurities from the device-active area of the wafer by transport to a predesigned region-called gettering layer (GL). We introduce an interface at z = d{sub GL}, at which the effect of the gettering mechanism on the metal impurity distribution in the wafer is quantified, e.g. by specifying currents or by interfacial reactions of metal impurities, self interstitials etc. between GL and wafer. In response metal impurities will diffuse out of the wafer into the gettering layer. Following such a concept, in general three species of the metal impurity (M) are involved in gettering: M{sub p} {l_arrow} M{sub i} {l_arrow} M{sub GL}. M{sub p} denotes immobile species in the wafer, which are precipitated into suicides or segregated at extended defects or whose diffusivity is too small to contribute noticeably to transport during the gettering procedure - like many substitutional metal species.

  17. Effect of nonmagnetic substituents Mg and Zn on the phase competition in the multiferroic antiferromagnet MnWO4

    OpenAIRE

    Meddar, Lynda; Josse, Michael; Deniard, Philippe; La, Carole; André, Gilles; Damay, Françoise; Petricek, Vaclav; Jobic, Stéphane; Whangbo, Myung-Hwan; Maglione, Mario; Payen, Christophe

    2010-01-01

    The effects of substituting nonmagnetic Mg2+ and Zn2+ ions for the Mn2+ (S = 5/2) ions on the structural, magnetic and dielectric properties of the multiferroic frustrated antiferromagnet MnWO4 were investigated. Polycrystalline samples of Mn1-xMgxWO4 and Mn1-xZnxWO4 (0

  18. Giant magneto-optical response in non-magnetic semiconductor BiTeI driven by bulk Rashba spin splitting

    OpenAIRE

    Demkó, L.; Schober, G. A. H.; Kocsis, V.; Bahramy, M.S.; Murakawa, H.; Lee, J. S.; Kézsmárki, I.; Arita, R.; Nagaosa, N.; Tokura, Y.

    2012-01-01

    We study the magneto-optical (MO) response of polar semiconductor BiTeI with giant bulk Rashba spin splitting at various carrier densities. Despite being non-magnetic, the material is found to yield a huge MO activity in the infrared region under moderate magnetic fields (

  19. Microstructure and mechanical properties of nonmagnetic Fe-25Mn-xCu-C steels by super solidus liquid phase sintering

    Science.gov (United States)

    Jia, Shanquan; Xiao, Zhiyu; Wang, Jun; Yang, Shuo; Guan, Hangjian; Zhu, Quanli

    2016-11-01

    In this work, nonmagnetic steels Fe-25Mn-xCu-C were prepared by high manganese pre-alloyed steel powders through powder metallurgy (PM) technique. Four types of steels specimen were created to investigate the microstructure evolving with sintering process, mechanical properties and magnetic properties. The microstructures, fracture surfaces, phase constitutions and mechanical properties of Fe-25Mn-xCu-C were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and tensile strength test. The results showed that super solidus liquid-phase sintering (SLPS) phenomenon was conclusively verified, for the first time, in the Fe-Mn pre-alloyed powders: Liquids generated by SLPS process from pre-alloyed powders could improve the binding condition between the particles and enhance the densification. X-ray diffraction (XRD) experiment and physical property measurement system (PPMS) measurement verified the nonmagnetic properties of steels with single austenite phase. It is confirmed that mechanical properties are intensively influenced by the characteristic and quantity of liquids between the matrix particles. The fracture mechanism of the steel is dominated by intergranular decohesion mode. The preliminary study found this kind of new non-magnetic steel exhibits relatively high density. With the efficiency in fabricating and the non-magnetic property, this work foresees good prospects for application in the steel components manufacturing industry.

  20. Fabrication of a Textured Non-Magnetic Ni-12at.%V Alloy Substrate for Coated Conductors

    DEFF Research Database (Denmark)

    Gao, M. M.; Grivel, Jean-Claude; Suo, H. L.;

    2011-01-01

    Ni-12at.%V alloy is a promising candidate for non-magnetic cube textured metallic substrates used for high temperature coated conductors. In this work, a textured Ni-12at.%V substrate has been fabricated by powder metallurgy route. After cold rolling and recrystallization annealing, a cube texture...

  1. Oscillatory impurity potential induced dynamics of doped quantum dots: Analysis based on coupled influence of impurity coordinate and impurity influenced domain

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Nirmal Kumar [Department of Physics, Suri Vidyasagar College, Suri, Birbhum 731 101, West Bengal (India); Ghosh, Manas, E-mail: pcmg77@rediffmail.com [Department of Chemistry, Physical Chemistry Section, Visva Bharati University, Santiniketan, Birbhum 731 235, West Bengal (India)

    2010-06-16

    Graphical abstract: The pattern of time evolution of eigenstates of a repulsive impurity doped quantum dot is explored. We have considered Gaussian impurity centers. Under a periodically fluctuating impurity potential, the system reveals a long time dynamics that is undulatory in nature. Coupled to the dopant location, the domain of influence of the impurity potential affects the separation between the eigenstates of the unperturbed system. The investigation points to a threshold value of spatial extension of impurity potential. Above this threshold value, the dopant location becomes important in monitoring the minimum value of impurity potential required to cause excitation. - Abstract: We explore the pattern of time evolution of eigenstates of a repulsive impurity doped quantum dot. The quantum dot is 2-dimensional and contains one electron which is harmonically confined. We have considered Gaussian impurity centers. A static transverse magnetic field is also present. Under a periodically fluctuating impurity potential, the system reveals a long time dynamics that is undulatory in nature. Coupled to the dopant location, the domain of influence of the impurity potential affects the separation between the eigenstates of the unperturbed system. The investigation points to a threshold value of spatial extension of impurity potential. Above this threshold value, the dopant location becomes important in monitoring the minimum value of impurity potential required to cause excitation.

  2. Hard sphere crystal nucleation and growth near large spherical impurities

    Science.gov (United States)

    de Villeneuve, V. W. A.; Verboekend, D.; Dullens, R. P. A.; Aarts, D. G. A. L.; Kegel, W. K.; Lekkerkerker, H. N. W.

    2005-11-01

    We report how large spherical impurities affect the nucleation and growth of hard sphere colloidal crystals. Both the impurities and the colloids are fluorescently labelled polymethylmetacrylate particles and are dispersed in an optically and density matching solvent mixture. Crystal growth, initiated either at the impurity surface, or at the sample bottom, was studied by imaging sequences of two-dimensional xy-slices in the plane of the impurity's centre of mass with a laser scanning confocal microscope. At least two factors determine whether a large impurity can function as a seed for heterogeneous nucleation: timescales and impurity curvature. The curvature needs to be sufficiently low for crystal nuclei to form on the impurity surface. If bulk crystal growth has already approached the impurity, bulk growth is dominant over growth of crystallites on the impurity surface. Such surface crystallites eventually reorient to adapt to the overall bulk crystal symmetry.

  3. From "They" Science to "Our" Science: Hip Hop Epistemology in STEAM Education

    Science.gov (United States)

    Dolberry, Maurice E.

    Hip hop has moved from being considered a type of music into being understood as a culture in which a prominent type of music originates. Hip hop culture has a philosophy and epistemological constructs as well. This study analyzed those constructs to determine how conceptions of science factor in hip hop worldviews. Pedagogical models in culturally responsive teaching and Science, Technology, Engineering, Arts, and Mathematics (STEAM) education were also examined to discern their philosophical connections with hip hop culture. These connections were used to create two theoretical models. The first one, Hip Hop Science, described how scientific thought functions in hip hop culture. The second model, Hip Hop STEAM Pedagogy, proposes how hip hop culture can inform STEAM teaching practices. The study began by using Critical Race Theory to create a theoretical framework proposing how the two theoretical models could be derived from the philosophical and pedagogical concepts. Content analysis and narrative inquiry were used to analyze data collected from scholarly texts, hip hop songs, and interviews with hip hop-responsive educators. The data from these sources were used initially to assess the adequacy of the proposed theoretical framework, and subsequently to improve its viability. Four overlapping themes emerged from the data analyses, including hip hop-resistance to formal education; how hip hop culture informs pedagogical practice in hip hop-responsive classrooms; conceptions of knowledge and reality that shape how hip hoppers conduct scientific inquiry; and hip hop-based philosophies of effective teaching for hip hoppers as a marginalized cultural group. The findings indicate that there are unique connections between hip hop epistemology, sciencemindedness, and pedagogical practices in STEAM education. The revised theoretical framework clarified the nature of these connections, and supported claims from prior research that hip hop culture provides viable sites of

  4. Removal Of Volatile Impurities From Copper Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    Winkel, L.; Schuler, A.; Frei, A.; Sturzenegger, M.

    2005-03-01

    To study the removal of volatile impurities from two different copper concentrates they have been heated on a thermo balance to temperatures between 900 and 1500 C. This sample treatment revealed that both concentrates undergo strong weight losses at 500 and 700 C. They were attributed to the removal of sulfur. Elemental analyses of the residues by ICP spectrometry have shown that the thermal treatment efficiently removes the volatile impurities. Already below 900 C most of the arsenic is removed by evaporation, the largest fraction of lead and zinc is removed in the temperature interval of 1300-1500 C. It was observed that quartz in the concentrate leads to the formation of a silicon-enriched phase besides a metal rich sulfide phase. The former is interpreted as an early stage of a silicate slag. Elemental analysis showed that the formation of this distinct slag phase does not hinder the efficient removal of volatile impurities. (author)

  5. Strong quantum scarring by local impurities

    Science.gov (United States)

    Luukko, Perttu J. J.; Drury, Byron; Klales, Anna; Kaplan, Lev; Heller, Eric J.; Räsänen, Esa

    2016-11-01

    We discover and characterise strong quantum scars, or quantum eigenstates resembling classical periodic orbits, in two-dimensional quantum wells perturbed by local impurities. These scars are not explained by ordinary scar theory, which would require the existence of short, moderately unstable periodic orbits in the perturbed system. Instead, they are supported by classical resonances in the unperturbed system and the resulting quantum near-degeneracy. Even in the case of a large number of randomly scattered impurities, the scars prefer distinct orientations that extremise the overlap with the impurities. We demonstrate that these preferred orientations can be used for highly efficient transport of quantum wave packets across the perturbed potential landscape. Assisted by the scars, wave-packet recurrences are significantly stronger than in the unperturbed system. Together with the controllability of the preferred orientations, this property may be very useful for quantum transport applications.

  6. Mic Power? Connections and the hip hop nation in Kampala, Uganda

    DEFF Research Database (Denmark)

    Schneidermann, Nanna

    2014-01-01

    Hip hop culture has been celebrated in the media and scholarship as a universal youth language, part of a global hip hop nation, and a type of counter-public. This article examines the everyday meanings and practices of hip hop among hip hop activists in Kampala, Uganda, specifically within...... the Batuuze rap group. Rather than portraying hip hop as a counter-public of the disempowered, I argue that the Batuuze engagement is based on what I call moral economy that enables the negotiation of connections in social and cultural networks towards what is considered a good life. Here, the hip hop nation...

  7. Magnetic impurities in spin-split superconductors

    Science.gov (United States)

    van Gerven Oei, W.-V.; Tanasković, D.; Žitko, R.

    2017-02-01

    Hybrid semiconductor-superconductor quantum dot devices are tunable physical realizations of quantum impurity models for a magnetic impurity in a superconducting host. The binding energy of the localized subgap Shiba states is set by the gate voltages and external magnetic field. In this work we discuss the effects of the Zeeman spin splitting, which is generically present both in the quantum dot and in the (thin-film) superconductor. The unequal g factors in semiconductor and superconductor materials result in respective Zeeman splittings of different magnitude. We consider both classical and quantum impurities. In the first case we analytically study the spectral function and the subgap states. The energy of bound states depends on the spin-splitting of the Bogoliubov quasiparticle bands as a simple rigid shift. For the case of collinear magnetization of impurity and host, the Shiba resonance of a given spin polarization remains unperturbed when it overlaps with the branch of the quasiparticle excitations of the opposite spin polarization. In the quantum case, we employ numerical renormalization group calculations to study the effect of the Zeeman field for different values of the g factors of the impurity and of the superconductor. We find that in general the critical magnetic field for the singlet-doublet transition changes nonmonotonically as a function of the superconducting gap, demonstrating the existence of two different transition mechanisms: Zeeman splitting of Shiba states or gap closure due to Zeeman splitting of Bogoliubov states. We also study how in the presence of spin-orbit coupling, modeled as an additional noncollinear component of the magnetic field at the impurity site, the Shiba resonance overlapping with the quasiparticle continuum of the opposite spin gradually broadens and then merges with the continuum.

  8. Hip Hop Dance Experience Linked to Sociocognitive Ability.

    Science.gov (United States)

    Bonny, Justin W; Lindberg, Jenna C; Pacampara, Marc C

    2017-01-01

    Expertise within gaming (e.g., chess, video games) and kinesthetic (e.g., sports, classical dance) activities has been found to be linked with specific cognitive skills. Some of these skills, working memory, mental rotation, problem solving, are linked to higher performance in science, technology, math, and engineering (STEM) disciplines. In the present study, we examined whether experience in a different activity, hip hop dance, is also linked to cognitive abilities connected with STEM skills as well as social cognition ability. Dancers who varied in hip hop and other dance style experience were presented with a set of computerized tasks that assessed working memory capacity, mental rotation speed, problem solving efficiency, and theory of mind. We found that, when controlling for demographic factors and other dance style experience, those with greater hip hop dance experience were faster at mentally rotating images of hands at greater angle disparities and there was a trend for greater accuracy at identifying positive emotions displayed by cropped images of human faces. We suggest that hip hop dance, similar to other more technical activities such as video gameplay, tap some specific cognitive abilities that underlie STEM skills. Furthermore, we suggest that hip hop dance experience can be used to reach populations who may not otherwise be interested in other kinesthetic or gaming activities and potentially enhance select sociocognitive skills.

  9. Hip Hop Dance Experience Linked to Sociocognitive Ability

    Science.gov (United States)

    Bonny, Justin W.; Lindberg, Jenna C.; Pacampara, Marc C.

    2017-01-01

    Expertise within gaming (e.g., chess, video games) and kinesthetic (e.g., sports, classical dance) activities has been found to be linked with specific cognitive skills. Some of these skills, working memory, mental rotation, problem solving, are linked to higher performance in science, technology, math, and engineering (STEM) disciplines. In the present study, we examined whether experience in a different activity, hip hop dance, is also linked to cognitive abilities connected with STEM skills as well as social cognition ability. Dancers who varied in hip hop and other dance style experience were presented with a set of computerized tasks that assessed working memory capacity, mental rotation speed, problem solving efficiency, and theory of mind. We found that, when controlling for demographic factors and other dance style experience, those with greater hip hop dance experience were faster at mentally rotating images of hands at greater angle disparities and there was a trend for greater accuracy at identifying positive emotions displayed by cropped images of human faces. We suggest that hip hop dance, similar to other more technical activities such as video gameplay, tap some specific cognitive abilities that underlie STEM skills. Furthermore, we suggest that hip hop dance experience can be used to reach populations who may not otherwise be interested in other kinesthetic or gaming activities and potentially enhance select sociocognitive skills. PMID:28146562

  10. Sputtering of a silicon surface: Preferential sputtering of surface impurities

    Energy Technology Data Exchange (ETDEWEB)

    Nietiadi, Maureen L. [Physics Department and Research Center OPTIMAS, University Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany); Rosandi, Yudi [Physics Department and Research Center OPTIMAS, University Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany); Department of Physics, Universitas Padjadjaran, Jatinangor, Sumedang 45363 (Indonesia); Lorinčík, Jan [Faculty of Science, J. E. Purkinje University, České mládeže 8, 400 96 Ústí nad Labem (Czech Republic); Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberská 57, 182 51 Praha (Czech Republic); Urbassek, Herbert M., E-mail: urbassek@rhrk.uni-kl.de [Physics Department and Research Center OPTIMAS, University Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany)

    2013-05-15

    We present molecular-dynamics simulations of the sputtering of an impurity atom off a Si 2×1 (100) surface by 2 keV Ar ions. The impurity is characterized by its mass and its binding energy to the Si substrate. We find that sputtering strongly decreases with the mass and even more strongly with the binding energy of the impurity atom to the matrix. The velocity of the impurity perpendicular to the surface is reduced with increasing impurity mass and binding energy. In terms of available ionization theories we can conclude that heavier impurities will have a smaller ionization probability.

  11. Correlations between locked modes and impurity influxes

    Energy Technology Data Exchange (ETDEWEB)

    Fishpool, G.M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Lawson, K.D. [UKAEA Culham Lab., Abingdon (United Kingdom)

    1994-07-01

    An analysis of pulses that were disturbed by medium Z impurity influxes (Cl, Cr, Fe and Ni) recorded during the 91/92 JET operations, has demonstrated that such influxes can result in MHD modes which subsequently ``lock``. A correlation is found between the power radiated by the influx and the time difference between the start of the influx and the beginning of the locked mode. The growth in the amplitude of the locked mode itself can lead to further impurity influxes. A correlation is noted between intense influxes (superior to 10 MW) and the mode ``unlocking``. (authors). 4 refs., 4 figs.

  12. Novel Bound States in Graphene with Impurities

    CERN Document Server

    Gupta, Kumar S

    2008-01-01

    We obtain a novel bound state spectrum of the low energy excitations near the Fermi points of graphene in the presence of a charge impurity. The effects of possible short range interactions induced by the impurity are modelled by suitable boundary conditions. The spectrum in the subcritical region of the effective Coulomb coupling is labelled by a parameter which characterizes the boundary conditions and determines the inequivalent quantizations of the system. In the supercritical region we obtain a renormalization group flow for the effective Coulomb coupling.

  13. The electronic structure of impurities in semiconductors

    CERN Multimedia

    Nylandsted larsen, A; Svane, A

    2002-01-01

    The electronic structure of isolated substitutional or interstitial impurities in group IV, IV-IV, and III-V compound semiconductors will be studied. Mössbauer spectroscopy will be used to investigate the incorporation of the implanted isotopes on the proper lattice sites. The data can be directly compared to theoretical calculations using the LMTO scheme. Deep level transient spectroscopy will be used to identify the band gap levels introduced by metallic impurities, mainly in Si~and~Si$ _{x}$Ge$_{1-x}$. \\\\ \\\\

  14. Identification, Characterization, and Quantification of Impurities of Safinamide Mesilate: Process-Related Impurities and Degradation Products.

    Science.gov (United States)

    Zou, Liang; Sun, Lili; Zhang, Hui; Hui, Wenkai; Zou, Qiaogen; Zhu, Zheying

    2017-07-01

    The characterization of process-related impurities and degradation products of safinamide mesilate (SAFM) in bulk drug and a stability-indicating HPLC method for the separation and quantification of all the impurities were investigated. Four process-related impurities (Imp-B, Imp-C, Imp-D, and Imp-E) were found in the SAFM bulk drug. Five degradation products (Imp-A, Imp-C, Imp-D, Imp-E, and Imp-F) were observed in SAFM under oxidative conditions. Imp-C, Imp-D, and Imp-E were also degradation products and process-related impurities. Remarkably, one new compound, identified as (S)-2-[4-(3-fluoro-benzyloxy) benzamido] propanamide (i.e., Imp-D), is being reported here as an impurity for the first time. Furthermore, the structures of the aforementioned impurities were characterized and confirmed via IR, NMR, and MS techniques, and the most probable formation mechanisms of all impurities proposed according to the synthesis route. Optimum separation was achieved on an Inertsil ODS-3 column (250 × 4.6 mm, 5 μm), using 0.1% formic acid in water (pH adjusted to 5.0) and acetonitrile as the mobile phase in gradient mode. The proposed method was found to be stability-indicating, precise, linear, accurate, sensitive, and robust for the quantitation of SAFM and its process-related substances, including its degradation products.

  15. Quantum Trajectory Approach to Molecular Dynamics Simulation with Surface Hopping

    CERN Document Server

    Feng, Wei; Li, Xin-Qi; Fang, Weihai

    2012-01-01

    The powerful molecular dynamics (MD) simulation is basically based on a picture that the atoms experience classical-like trajectories under the exertion of classical force field determined by the quantum mechanically solved electronic state. In this work we propose a quantum trajectory approach to the MD simulation with surface hopping, from an insight that an effective "observation" is actually implied in theMDsimulation through tracking the forces experienced, just like checking the meter's result in the quantum measurement process. This treatment can build the nonadiabatic surface hopping on a dynamical foundation, instead of the usual artificial and conceptually inconsistent hopping algorithms. The effects and advantages of the proposed scheme are preliminarily illustrated by a two-surface model system.

  16. Processing Methods for Conical Scan Hopped-Frequency Signal

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-hong; LONG Teng

    2006-01-01

    The new radar system of combination of the hopped-frequency with the conical scanis presented. According to the principle and expression of the conical scan hopped-frequency signal, the angle processing method in which angle information is obtained by taking discrete Fourier transform (DFT) for the conical envelop o f each scattering centre by means of high range resolution profile (HRRP) is presented,and the corresponding formula is derived. The influence of non-ideal factors, such as amplitude fluctuation noise and system noise, leakage of time and frequency domain, unstable rotation of antenna, and missile rotation, on angle-measurement precision and the possible solving methods are also focused on. The simulation results show that the combination of the hopped-frequency and conical scan system could get satisfactory angle information, which could ensure good quality when used in practical tracking radar.

  17. On the Effective Capacity of Two-Hop Communication Systems

    CERN Document Server

    Qiao, Deli; Velipasalar, Senem

    2010-01-01

    In this paper, two-hop communication between a source and a destination with the aid of an intermediate relay node is considered. Both the source and intermediate relay node are assumed to operate under statistical quality of service (QoS) constraints imposed as limitations on the buffer overflow probabilities. It is further assumed that the nodes send the information at fixed power levels and have perfect channel side information. In this scenario, the maximum constant arrival rates that can be supported by this two-hop link are characterized by finding the effective capacity. Through this analysis, the impact upon the throughput of having buffer constraints at the source and intermediate-hop nodes is identified.

  18. Surface hopping in laser-driven molecular dynamics

    Science.gov (United States)

    Fiedlschuster, T.; Handt, J.; Gross, E. K. U.; Schmidt, R.

    2017-06-01

    A theoretical justification of the empirical surface hopping method for the laser-driven molecular dynamics is given by utilizing the formalism of the exact factorization of the molecular wave function [Abedi et al., Phys. Rev. Lett. 105, 123002 (2010), 10.1103/PhysRevLett.105.123002] in its quantum-classical limit. Employing an exactly solvable H2+-like model system, it is shown that the deterministic classical nuclear motion on a single time-dependent surface in this approach describes the same physics as stochastic (hopping-induced) motion on several surfaces, provided Floquet surfaces are applied. Both quantum-classical methods do describe reasonably well the exact nuclear wave-packet dynamics for extremely different dissociation scenarios. Hopping schemes using Born-Oppenheimer surfaces or instantaneous Born-Oppenheimer surfaces fail completely.

  19. Surface hopping methodology in laser-driven molecular dynamics

    CERN Document Server

    Fiedlschuster, T; Gross, E K U; Schmidt, R

    2016-01-01

    A theoretical justification of the empirical surface hopping method for the laser-driven molecular dynamics is given utilizing the formalism of the exact factorization of the molecular wavefunction [Abedi et al., PRL $\\textbf{105}$, 123002 (2010)] in its quantum-classical limit. Employing an exactly solvable $\\textrm H_2^{\\;+}$-like model system, it is shown that the deterministic classical nuclear motion on a single time-dependent surface in this approach describes the same physics as stochastic (hopping-induced) motion on several surfaces, provided Floquet surfaces are applied. Both quantum-classical methods do describe reasonably well the exact nuclear wavepacket dynamics for extremely different dissociation scenarios. Hopping schemes using Born-Oppenheimer surfaces or instantaneous Born-Oppenheimer surfaces fail completely.

  20. Comparison of Rheological Properties of Hopped Wort and Malt Wort

    Directory of Open Access Journals (Sweden)

    Petr Trávníček

    2015-01-01

    Full Text Available The aim of this work is determination rheological properties of hopped wort and malt wort and their comparison. In the paper following rheological properties has been described: the dependence of viscosity on a temperature of a sample and hysteresis loop test. The time dependence test was performed for a confirmation thixotropic behaviour. Based on measured values Arrhenius mathematical model has been applied. The activation energy was determined by using of this model. Tests have been carried out in the temperature range from 5 °C to 40 °C. Rheological tests proved that malt wort behaves as Newtonian fluid in all temperatures and hopped wort behaves as non-Newtonian fluid at low temperatures. Thixotropic behaviour is caused by the content of the rests of hops heads or malt scraps.

  1. Switched diversity strategies for dual-hop relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine

    2011-04-29

    This paper investigates the effect of different switched diversity configurations on the implementation complexity and achieved performance of dual-hop amplify-and-forward (AF) relaying networks. A low-complexity model of the relay station is adopted, wherein single-input single-output antenna configuration is employed. Each of the transmitter and the receiver however employs multiple antennas to improve the overall link performance. Single-phase and two-phase based receive switching strategies are investigated assuming optimum first hop signal-to-noise ratio (SNR). Moreover, the simple scheme in which the switched diversity is applied independently over the two hops is studied using tight upper bounds. Thorough performance comparisons and switching thresholds optimization for the aforementioned strategies are presented. Simulation results are also provided to validate the mathematical development and to verify the numerical computations.

  2. Development of Impurity Profiling Methods Using Modern Analytical Techniques.

    Science.gov (United States)

    Ramachandra, Bondigalla

    2017-01-02

    This review gives a brief introduction about the process- and product-related impurities and emphasizes on the development of novel analytical methods for their determination. It describes the application of modern analytical techniques, particularly the ultra-performance liquid chromatography (UPLC), liquid chromatography-mass spectrometry (LC-MS), high-resolution mass spectrometry (HRMS), gas chromatography-mass spectrometry (GC-MS) and high-performance thin layer chromatography (HPTLC). In addition to that, the application of nuclear magnetic resonance (NMR) spectroscopy was also discussed for the characterization of impurities and degradation products. The significance of the quality, efficacy and safety of drug substances/products, including the source of impurities, kinds of impurities, adverse effects by the presence of impurities, quality control of impurities, necessity for the development of impurity profiling methods, identification of impurities and regulatory aspects has been discussed. Other important aspects that have been discussed are forced degradation studies and the development of stability indicating assay methods.

  3. New Iterated Decoding Algorithm Based on Differential Frequency Hopping System

    Institute of Scientific and Technical Information of China (English)

    LIANG Fu-lin; LUO Wei-xiong

    2005-01-01

    A new iterated decoding algorithm is proposed for differential frequency hopping (DFH) encoder concatenated with multi-frequency shift-key (MFSK) modulator. According to the character of the frequency hopping (FH) pattern trellis produced by DFH function, maximum a posteriori (MAP) probability theory is applied to realize the iterate decoding of it. Further, the initial conditions for the new iterate algorithm based on MAP algorithm are modified for better performance. Finally, the simulation result compared with that from traditional algorithms shows good anti-interference performance.

  4. RESEARCH ON JUMPING SEQUENCE PLANNING ISSUES OF HOPPING ROBOTS

    Institute of Scientific and Technical Information of China (English)

    LIUZhuang-zhi; ZHUJian-ying

    2004-01-01

    The wheeled or crawled robots often suffer from big obstacles or ditches, so a hopping robot needs to fit the tough landform in the field environments. In order to jump over obstacles rapidly, a jumping sequence must be generated based on the landform information from sensors or user input. The planning method for planar mobile robots is compared with that of hopping robots. Several factors can change the planning result. Adjusting these coefficients, a heuristic searching algorithm for the jumping sequence is developed on a simplified landform. Calculational result indicates that the algorithm can achieve safety and efficient control sequences for a desired goal.

  5. Construction of Frequency Hopping Sequence Set Based upon Generalized Cyclotomy

    CERN Document Server

    Liu, Fang; Zhou, Zhengchun; Tang, Xiaohu

    2010-01-01

    Frequency hopping (FH) sequences play a key role in frequency hopping spread spectrum communication systems. It is important to find FH sequences which have simultaneously good Hamming correlation, large family size and large period. In this paper, a new set of FH sequences with large period is proposed, and the Hamming correlation distribution of the new set is investigated. The construction of new FH sequences is based upon Whiteman's generalized cyclotomy. It is shown that the proposed FH sequence set is optimal with respect to the average Hamming correlation bound.

  6. Optimal Transmission Policies for Energy Harvesting Two-hop Networks

    CERN Document Server

    Orhan, Oner

    2012-01-01

    In this paper, a two-hop communication system with energy harvesting nodes is considered. Unlike battery powered wireless nodes, both the source and the relay are able to harvest energy from environment during communication, therefore, both data and energy causality over the two hops need to be considered. Assuming both nodes know the harvested energies in advance, properties of optimal transmission policies to maximize the delivered data by a given deadline are identified. Using these properties, optimal power allocation and transmission schedule for the case in which both nodes harvest two energy packets is developed.

  7. Linear Span of the Optimal Frequency Hopping Sequences from Irreducible Cyclic Co des

    Institute of Scientific and Technical Information of China (English)

    GAO Juntao; HU Yupu; LI Xuelian

    2015-01-01

    Optimal set of the frequency hopping se-quences can be derived from some irreducible cyclic codes. This paper determines the linear span of the frequency hopping sequences in the optimal set. The linear span is much less than the length of the frequency hopping se-quences. In order to improve the linear span, we use two types of permutation polynomials, power permutation and binomial permutation, to transform the optimal set of the frequency hopping sequences. The transformed frequency hopping sequences have optimal Hamming correlation and larger linear span than the original frequency hopping se-quences. Compared with the original frequency hopping sequences, the transformed optimal frequency hopping se-quences have higher security to resist the cryptanalytic method.

  8. Far-from-equilibrium growth of magnetic thin films with Blume-Capel impurities

    Science.gov (United States)

    Mazzitello, Karina I.; Candia, Julián; Albano, Ezequiel V.

    2015-04-01

    We investigate the irreversible growth of (2 +1 ) -dimensional magnetic thin films. The spin variable can adopt three states (si=±1 ,0 ), and the system is in contact with a thermal bath of temperature T . The deposition process depends on the change of the configuration energy, which, by analogy to the Blume-Capel Hamiltonian in equilibrium systems, depends on Ising-like couplings between neighboring spins (J ) and has a crystal field (D ) term that controls the density of nonmagnetic impurities (si=0 ). Once deposited, particles are not allowed to flip, diffuse, or detach. By means of extensive Monte Carlo simulations, we obtain the phase diagram in the crystal field vs temperature parameter space. We show clear evidence of the existence of a tricritical point located at Dt/J =1.145 (10 ) and kBTt/J =0.425 (10 ) , which separates a first-order transition curve at lower temperatures from a critical second-order transition curve at higher temperatures, in analogy with the previously studied equilibrium Blume-Capel model. Furthermore, we show that, along the second-order transition curve, the critical behavior of the irreversible growth model can be described by means of the critical exponents of the two-dimensional Ising model under equilibrium conditions. Therefore, our findings provide a link between well-known theoretical equilibrium models and nonequilibrium growth processes that are of great interest for many experimental applications, as well as a paradigmatic topic of study in current statistical physics.

  9. Effects of correlated hybridization in the single-impurity Anderson model

    Science.gov (United States)

    Líbero, Valter; Veiga, Rodrigo

    2013-03-01

    The development of new materials often dependents on the theoretical foundations which study the microscopic matter, i.e., the way atoms interact and create distinct configurations. Among the interesting materials, those with partially filled d or f orbitals immersed in nonmagnetic metals have been described by the Anderson model, which takes into account Coulomb correlation (U) when a local level (energy Ed) is doubled occupied, and an electronic hybridization between local levels and conduction band states. In addition, here we include a correlated hybridization term, which depends on the local-level occupation number involved. This term breaks particle-hole symmetry (even when U + 2Ed = 0), enhances charge fluctuations on local levels and as a consequence strongly modifies the crossover between the Hamiltonian fixed-points, even suppressing one or other. We exemplify these behaviors showing data obtained from the Numerical Renormalization Group (NRG) computation for the impurity temperature-dependent specific heat, entropy and magnetic susceptibility. The interleaving procedure is used to recover the continuum spectrum after the NRG-logarithmic discretization of the conduction band. Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP.

  10. Parallel Impurity Spreading During Massive Gas Injection

    Science.gov (United States)

    Izzo, V. A.

    2016-10-01

    Extended-MHD simulations of disruption mitigation in DIII-D demonstrate that both pre-existing islands (locked-modes) and plasma rotation can significantly influence toroidal spreading of impurities following massive gas injection (MGI). Given the importance of successful disruption mitigation in ITER and the large disparity in device parameters, empirical demonstrations of disruption mitigation strategies in present tokamaks are insufficient to inspire unreserved confidence for ITER. Here, MHD simulations elucidate how impurities injected as a localized jet spread toroidally and poloidally. Simulations with large pre-existing islands at the q = 2 surface reveal that the magnetic topology strongly influences the rate of impurity spreading parallel to the field lines. Parallel spreading is largely driven by rapid parallel heat conduction, and is much faster at low order rational surfaces, where a short parallel connection length leads to faster thermal equilibration. Consequently, the presence of large islands, which alter the connection length, can slow impurity transport; but the simulations also show that the appearance of a 4/2 harmonic of the 2/1 mode, which breaks up the large islands, can increase the rate of spreading. This effect is seen both for simulations with spontaneously growing and directly imposed 4/2 modes. Given the prevalence of locked-modes as a cause of disruptions, understanding the effect of large islands is of particular importance. Simulations with and without islands also show that rotation can alter impurity spreading, even reversing the predominant direction of spreading, which is toward the high-field-side in the absence of rotation. Given expected differences in rotation for ITER vs. DIII-D, rotation effects are another important consideration when extrapolating experimental results. Work supported by US DOE under DE-FG02-95ER54309.

  11. Flexible Surface Hopping Approach to Model the Crossover from Hopping to Band-like Transport in Organic Crystals.

    Science.gov (United States)

    Wang, Linjun; Beljonne, David

    2013-06-06

    Two distinct pictures are usually evoked when modeling charge transport in organic crystals, that is, band and hopping models, the signature of which is conveyed by a characteristic temperature dependence of mobility. Here, we present a novel flexible surface hopping approach compliant with general Hamiltonians that is able to grasp the crossover from hopping to band-like transport regimes. This approach is applied to solve a one-dimensional mixed quantum-classical model and to calculate the temperature dependence of charge mobility along with the degree of charge spatial localization. It is found that the roles of both local and nonlocal electron-phonon couplings strongly depend on the intrinsic charge localization strength.

  12. Suppression of Plant Immune Responses by the Pseudomonas savastanoi pv. savastanoi NCPPB 3335 Type III Effector Tyrosine Phosphatases HopAO1 and HopAO2

    Science.gov (United States)

    Castañeda-Ojeda, María Pilar; Moreno-Pérez, Alba; Ramos, Cayo; López-Solanilla, Emilia

    2017-01-01

    The effector repertoire of the olive pathogen P. savastanoi pv. savastanoi NCPPB 3335 includes two members of the HopAO effector family, one of the most diverse T3E families of the P. syringae complex. The study described here explores the phylogeny of these dissimilar members, HopAO1 and HopAO2, among the complex and reveals their activities as immune defense suppressors. Although HopAO1 is predominantly encoded by phylogroup 3 strains isolated from woody organs of woody hosts, both HopAO1 and HopAO2 are phylogenetically clustered according to the woody/herbaceous nature of their host of isolation, suggesting host specialization of the HopAO family across the P. syringae complex. HopAO1 and HopAO2 translocate into plant cells and show hrpL-dependent expression, which allows their classification as actively deployed type III effectors. Our data also show that HopAO1 and HopAO2 possess phosphatase activity, a hallmark of the members of this family. Both of them exert an inhibitory effect on early plant defense responses, such as ROS production and callose deposition, and are able to suppress ETI responses induced by the effectorless polymutant of P. syringae pv. tomato DC3000 (DC3000D28E) in Nicotiana. Moreover, we demonstrate that a ΔhopAO1 mutant of P. savastanoi NCPBB 3335 exhibits a reduced fitness and virulence in olive plants, which supports the relevance of this effector during the interaction of this strain with its host plants. This work contributes to the field with the first report regarding functional analysis of HopAO homologs encoded by P. syringae or P. savastanoi strains isolated from woody hosts. PMID:28529516

  13. Suppression of Plant Immune Responses by the Pseudomonas savastanoi pv. savastanoi NCPPB 3335 Type III Effector Tyrosine Phosphatases HopAO1 and HopAO2

    Directory of Open Access Journals (Sweden)

    María Pilar Castañeda-Ojeda

    2017-05-01

    Full Text Available The effector repertoire of the olive pathogen P. savastanoi pv. savastanoi NCPPB 3335 includes two members of the HopAO effector family, one of the most diverse T3E families of the P. syringae complex. The study described here explores the phylogeny of these dissimilar members, HopAO1 and HopAO2, among the complex and reveals their activities as immune defense suppressors. Although HopAO1 is predominantly encoded by phylogroup 3 strains isolated from woody organs of woody hosts, both HopAO1 and HopAO2 are phylogenetically clustered according to the woody/herbaceous nature of their host of isolation, suggesting host specialization of the HopAO family across the P. syringae complex. HopAO1 and HopAO2 translocate into plant cells and show hrpL-dependent expression, which allows their classification as actively deployed type III effectors. Our data also show that HopAO1 and HopAO2 possess phosphatase activity, a hallmark of the members of this family. Both of them exert an inhibitory effect on early plant defense responses, such as ROS production and callose deposition, and are able to suppress ETI responses induced by the effectorless polymutant of P. syringae pv. tomato DC3000 (DC3000D28E in Nicotiana. Moreover, we demonstrate that a ΔhopAO1 mutant of P. savastanoi NCPBB 3335 exhibits a reduced fitness and virulence in olive plants, which supports the relevance of this effector during the interaction of this strain with its host plants. This work contributes to the field with the first report regarding functional analysis of HopAO homologs encoded by P. syringae or P. savastanoi strains isolated from woody hosts.

  14. Manifestation of hopping conductivity and granularity within phase diagrams of LaO1-x F x BiS2, Sr1-x La x FBiS2 and related BiS2-based compounds

    Science.gov (United States)

    Arouca, R.; Silva Neto, M. B.; Chaves, C. M.; Nagao, M.; Watauchi, S.; Tanaka, I.; ElMassalami, M.

    2017-09-01

    Layered BiS 2 -based series, such as LaO 1-x F x BiS 2 and Sr 1-x La x FBiS 2 , offer ideal examples for studying normal and superconducting phase diagram of a solid solution that evolves from a nonmagnetic band-insulator parent. We constructed typical x-T phase diagrams of these systems based on events occurring in thermal evolution of their electrical resistivity, ρ(x, T) . Overall evolution of these diagrams can be rationalized in terms of (i) Mott-Efros-Shklovskii scenario which, within the semiconducting x regime (x_MIT = Mott metal-insulator transition), describes the doping influence on the thermally activated hopping conductivity. (ii) A granular metal (superconductor) scenario which, within x_MITpressure or heat treatment.

  15. Monte Carlo method for magnetic impurities in metals

    Science.gov (United States)

    Hirsch, J. E.; Fye, R. M.

    1986-01-01

    The paper discusses a Monte Carlo algorithm to study properties of dilute magnetic alloys; the method can treat a small number of magnetic impurities interacting wiith the conduction electrons in a metal. Results for the susceptibility of a single Anderson impurity in the symmetric case show the expected universal behavior at low temperatures. Some results for two Anderson impurities are also discussed.

  16. Metal-based impurities in graphenes: application for electroanalysis.

    Science.gov (United States)

    Chee, Sze Yin; Pumera, Martin

    2012-05-01

    We show here that metallic impurities presented in graphenes prepared from graphite can be usefully employed for electroanalysis. We demonstrate that cumene hydroperoxide electrochemical reduction on graphene containing iron-based impurities provides significantly larger voltammetric currents than the same experiment using iron oxide nanoparticles. This opens doors for turning metallic impurities into potentially useful components of graphene based electrochemical systems.

  17. Enhancing current-induced torques by abutting additional spin polarizer layer to nonmagnetic metal layer

    Science.gov (United States)

    Go, Gyungchoon; Lee, Kyung-Jin; Kim, Young Keun

    2017-04-01

    Recently, the switching of a perpendicularly magnetized ferromagnet (FM) by injecting an in-plane current into an attached non-magnet (NM) has become of emerging technological interest. This magnetization switching is attributed to the spin-orbit torque (SOT) originating from the strong spin-orbit coupling of the NM layer. However, the switching efficiency of the NM/FM structure itself may be insufficient for practical use, as for example, in spin transfer torque (STT)-based magnetic random access memory (MRAM) devices. Here we investigate spin torque in an NM/FM structure with an additional spin polarizer (SP) layer abutted to the NM layer. In addition to the SOT contribution, a spin-polarized current from the SP layer creates an extra spin chemical potential difference at the NM/FM interface and gives rise to a STT on the FM layer. We show that, using typical parameters including device width, thickness, spin diffusion length, and the spin Hall angle, the spin torque from the SP layer can be much larger than that from the spin Hall effect (SHE) of the NM.

  18. Spin filtering and switching action in a diamond network with magnetic-nonmagnetic atomic distribution

    Science.gov (United States)

    Pal, Biplab; Dutta, Paramita

    2016-09-01

    We propose a simple model quantum network consisting of diamond-shaped plaquettes with deterministic distribution of magnetic and non-magnetic atoms in presence of a uniform external magnetic flux in each plaquette and predict that such a simple model can be a prospective candidate for spin filter as well as flux driven spintronic switch. The orientations and the amplitudes of the substrate magnetic moments play a crucial role in the energy band engineering of the two spin channels which essentially gives us a control over the spin transmission leading to a spin filtering effect. The externally tunable magnetic flux plays an important role in inducing a switch on-switch off effect for both the spin states indicating the behavior like a spintronic switch. Even a correlated disorder configuration in the on-site potentials and in the magnetic moments may lead to disorder-induced spin filtering phenomenon where one of the spin channel gets entirely blocked leaving the other one transmitting over the entire allowed energy regime. All these features are established by evaluating the density of states and the two terminal transmission probabilities using the transfer-matrix formalism within a tight-binding framework. Experimental realization of our theoretical study may be helpful in designing new spintronic devices.

  19. Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

    Science.gov (United States)

    Fan, Liren; Song, Jiqing; Bai, Wenbo; Wang, Shengping; Zeng, Ming; Li, Xiaoming; Zhou, Yang; Li, Haifeng; Lu, Haiwei

    2016-02-01

    A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shell Fe3O4@SiO2 (FS) nanoparticles. These reactions used a silane coupling agent and sodium chloroacetate. The results show that FS@IDA could chelate the heavy metal component of Cd, Zn, Pb, Cu and Ni carbonates, lead sulfate and lead chloride in water-insoluble salt systems. The resulting FS@IDA-Cd and FS@IDA-Pb chelates could be magnetically separated, resulting in removal rates of approximately 84.9% and 72.2% for Cd and Pb, respectively. FS@IDA could not remove the residual heavy metals and those bound to organic matter in the soil. FS@IDA did not significantly alter the chemical composition of the soil, and it allowed for fast chelating capture, simple magnetic separation and facilitated heavy metal elution. FS@IDA could also be easily prepared and reprocessed.

  20. Induced magnetization spiral in a nonmagnetic metal sandwiched between two ferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Mathon, J.; Umerski, A.; Villeret, Murielle E-mail: m.a.villeret@city.ac.uk; Muniz, R.B.; Edwards, D.M

    2000-07-01

    Calculation of the magnetic moment induced in a non-magnetic metal, sandwiched between two ferromagnets with magnetizations at an arbitrary angle, is reported. It is found that the induced magnetization rotates along a complex three-dimensional spiral and can undergo many complete 360 deg. rotations. A simple free-electron model is used to derive an analytic formula for the twist angle phi inside the spacer. This demonstrates that, contrary to the behavior of magnetization inside a domain wall in a ferromagnet, phi varies non-uniformly inside the spacer and exhibits plateaus of almost constant rotation separated by regions of sharp rotations by large angles. The calculation is extended to the case of a realistic Co/Cu/Co(0 0 1) trilayer described by s, p, d tight-binding bands fitted to an ab initio band structure. An analytic formula for the components of the induced moment (and hence, for phi) is derived using the stationary phase approximation. Its validity is tested against a fully numerical calculation using the same band structure. The formula shows that the components of the induced magnetization each oscillate with a predominant short period determined by the Cu Fermi surface neck extrema. The twist angle again displays the same remarkable behavior as in the free-electron model and depends in an intricate manner on geometrical properties of the spacer Fermi surface as well as on the degree of confinement of carriers in the spacer quantum well.

  1. Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S. C., E-mail: subhash.laserlab@gmail.com; Gopal, R. [Laser Spectroscopy and Nanomaterials Lab, Department of Physics, University of Allahabad, Allahabad-211002 (India); Kotnala, R. K. [Magnetic Standardization Division, National Physical Laboratory, K.S. Krishnan Road, New Delhi (India)

    2015-08-14

    Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, related to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects.

  2. Induced magnetization spiral in a nonmagnetic metal sandwiched between two ferromagnets

    CERN Document Server

    Mathon, J; Villeret, M; Muniz, R B; Edwards, D M

    2000-01-01

    Calculation of the magnetic moment induced in a non-magnetic metal, sandwiched between two ferromagnets with magnetizations at an arbitrary angle, is reported. It is found that the induced magnetization rotates along a complex three-dimensional spiral and can undergo many complete 360 deg. rotations. A simple free-electron model is used to derive an analytic formula for the twist angle phi inside the spacer. This demonstrates that, contrary to the behavior of magnetization inside a domain wall in a ferromagnet, phi varies non-uniformly inside the spacer and exhibits plateaus of almost constant rotation separated by regions of sharp rotations by large angles. The calculation is extended to the case of a realistic Co/Cu/Co(0 0 1) trilayer described by s, p, d tight-binding bands fitted to an ab initio band structure. An analytic formula for the components of the induced moment (and hence, for phi) is derived using the stationary phase approximation. Its validity is tested against a fully numerical calculation u...

  3. Magnetic and nonmagnetic doping dependence of the conducting surface states in Sm B6

    Science.gov (United States)

    Kang, B. Y.; Min, Chul-Hee; Lee, S. S.; Song, M. S.; Cho, K. K.; Cho, B. K.

    2016-10-01

    Kondo insulator Sm B6 has attracted attention because it can realize new topological phenomena driven by the interplay between strong correlation effect and topology. However, its topological nature is still under debate. To examine the topological aspect, we demonstrate the nonmagnetic La and magnetic Ce doping dependence of the resistance of Sm B6 . Moreover, the resistance ratios of different thicknesses are analyzed to confirm the surface contribution. Lightly doped La samples show a purely conducting surface region at low temperature, whereas the lightly doped Ce samples do not have any conducting region at low temperature. Furthermore, based on the analysis of the electrical transport data of S m1 -xL axB6 (0.0 ≤x ≤1.0 ), an electronic phase diagram was found, composed of four regions: region I (0.0 ≤x ≤0.06 ), II (0.1 ≤x ≤0.15 ), III (x ≈0.2 ) , and IV (0.25 ≤x ≤1.0 ). Region I is characterized by the presence of conducting surface states, region II is characterized by the insulating phase due to the d -f hybridization gap without the conducting surface state, region III is characterized by the disappearance of the d -f hybridization gap and the existence of valence fluctuation, and region IV is a typical metallic state.

  4. Physics of Nonmagnetic Relativistic Thermal Plasmas. Ph.D. Thesis - Calif. Univ., San Diego

    Science.gov (United States)

    Dermer, C. D.

    1984-01-01

    A detailed treatment of the kinematics of relativistic systems of particles and photons is presented. In the case of a relativistic Maxwell-Boltzmann distribution of particles, the reaction rate and luminosity are written as single integrals over the invariant cross section, and the production spectrum is written as a double integral over the cross section differential in the energy of the produced particles (or photons) in the center-of-momentum system of two colliding particles. The results are applied to the calculation of the annihilation spectrum of a thermal electron-positron plasma, confirming previous numerical and analytic results. Relativistic thermal electron-ion and electron-electron bremsstrahlung are calculated exactly to lowest order, and relativistic thermal electron-positron bremsstrahlung is calculated in an approximate fashion. An approximate treatment of relativistic Comptonization is developed. The question of thermalization of a relativistic plasma is considered. A formula for the energy loss or exchange rate from the interaction of two relativistic Maxwell-Boltzmann plasmas at different temperatures is derived. Application to a stable, uniform, nonmagnetic relativistic thermal plasma is made. Comparison is made with other studies.

  5. SQUID magnetometer using sensitivity correction signal for non-magnetic metal contaminants detection

    Science.gov (United States)

    Yagi, Toshifumi; Ohashi, Masaharu; Sakuta, Ken

    2016-11-01

    Measurement methods with SQUID can accurately detect small magnetic metal contaminants based on their magnetic remanence. But, a high-frequency excitation is necessary to detect nonmagnetic metals, on the base of contrasts in electric conductivity. In this work, an open loop technique is introduced to facilitate this. The SQUID is negative feedback controlled (flux locked loop (FLL) operation) for the low frequency range, which includes significant noise due to the movement of the magnetic body or the change of the ambient magnetic field composed of the geomagnetic field and technical signals, and it operates in an open loop configuration for the high frequency range. When using the open loop technique, negative feedback is not applied to the high frequency range. Consequently, the V-Φ characteristic changes due to various causes, which leads to variations in the conversion factor between the SQUID output voltage and the magnetic field. In this study, conversion techniques for the magnetic field for open loop operation of SQUID in the high frequency range are examined.

  6. Direct X-Ray Imaging of Transient Spin Accumulation near a Ferromagnet/Nonmagnet Interface

    Science.gov (United States)

    Chen, Zhao; Kukreja, Roopali; Bonetti, Stefano; Backes, Dirk; Kent, Andrew; Katine, Jordan; Durr, Hermann; Ohldag, Hendrik; Stohr, Joachim

    2015-03-01

    The physics of spin transport across a ferromagnet/nonmagnet interface is not well understood, even though such interfaces are common in spintronic devices. We use time-resolved x-ray spectro-microscopy to directly image transient spin accumulation in a Cu film caused by an injected spin current from an adjacent Co film. The measurement uses element-specific, circularly polarized x-rays detected via a scanning transmission x-ray microscope (STXM) in conjunction with 1.28MHz temporal modulation for remarkably increased x-ray sensitivity to spin signals. The transient moments per atom within the spin diffusion length from the interface were measured to be 8 x 10-5μB per Cu atom and 1.5 x 10-4μB per Co atom. The transient spin signal in Cu is found to be confined to states at the Fermi level, as expected, but we also observe a second peak of the same spin polarization in the spin accumulation signal that is 0.7eV higher than Fermi. The transient moments in the 28nm thick Cu layer exhibit the same spin sign as both the hybridization-induced static spins in Cu at the Cu/Co interface and the spins in the Co film. In contrast, the transient moments in the Co layer have the opposite sign, consistent with magnetization depleting from the Co polarizing layer.

  7. Post-Menopausal Vaginal Hemorrhage Related to the Use of a Hop-Containing Phytotherapeutic Product

    NARCIS (Netherlands)

    van Hunsel, Florence; van de Koppel, Sonja; van Puijenbroek, Eugène

    2015-01-01

    Two 54-year-old women developed abdominal cramps and vaginal hemorrhage as a result of endometrial hyperplasia during treatment with a hop-containing phytotherapeutic product (MenoCool®) for post-menopausal complaints. The women used the hop-containing phytotherapeutic product (418 mg of hop per tab

  8. Flipping the Misogynist Script: Gender, Agency, Hip Hop and Music Education

    Science.gov (United States)

    Tobias, Evan S.

    2014-01-01

    Excluding Hip Hop culture and rap music from music education misses opportunities for addressing key aspects of popular culture, society, and students' lives. This article addresses intersections of Hip Hop, gender, and music education to forward potential Hip Hop praxis. After tracing related scholarship, I discuss and problematize…

  9. Flipping the Misogynist Script: Gender, Agency, Hip Hop and Music Education

    Science.gov (United States)

    Tobias, Evan S.

    2014-01-01

    Excluding Hip Hop culture and rap music from music education misses opportunities for addressing key aspects of popular culture, society, and students' lives. This article addresses intersections of Hip Hop, gender, and music education to forward potential Hip Hop praxis. After tracing related scholarship, I discuss and problematize…

  10. Wish to Live: The Hip-Hop Feminism Pedagogy Reader. Educational Psychology. Volume 3

    Science.gov (United States)

    Brown, Ruth Nicole, Ed.; Kwakye, Chamara Jewel, Ed.

    2012-01-01

    "Wish To Live: The Hip-hop Feminism Pedagogy Reader" moves beyond the traditional understanding of the four elements of hip-hop culture--rapping, breakdancing, graffiti art, and deejaying--to articulate how hip-hop feminist scholarship can inform educational practices and spark, transform, encourage, and sustain local and global youth…

  11. Post-Menopausal Vaginal Hemorrhage Related to the Use of a Hop-Containing Phytotherapeutic Product

    NARCIS (Netherlands)

    van Hunsel, Florence; van de Koppel, Sonja; van Puijenbroek, Eugène

    2015-01-01

    Two 54-year-old women developed abdominal cramps and vaginal hemorrhage as a result of endometrial hyperplasia during treatment with a hop-containing phytotherapeutic product (MenoCool®) for post-menopausal complaints. The women used the hop-containing phytotherapeutic product (418 mg of hop per

  12. First report of hop stunt viroid from sweet cherry with dapple apple fruit symptoms in China

    Science.gov (United States)

    Hop stunt viroid (HSVd), the type member of the genus Hostuviroid, family Pospiviroidae, was first described from hops with stunt disease in Japan. HSVd has a wide host range that includes hop, cucumber, citrus, grapevine, plum, pear, peach, apricot and almond and is the causal agent of serious dis...

  13. Measurement of the nonmagnetic coating thickness of core-shell magnetic nanoparticles by controlled magnetization magnetic force microscopy

    Science.gov (United States)

    Angeloni, L.; Passeri, D.; Scaramuzzo, F. A.; Di Iorio, D.; Barteri, M.; Mantovani, D.; Rossi, M.

    2016-06-01

    Magnetic nanoparticles (MNPs) represent an interesting tool for several biomedical applications. In order to improve the dispersion stability, the biocompatibility and bio-functionality, MNPs need to be coated with non-magnetic films. The optimization of these systems requires the deep characterization not only of the magnetic core, but also of the coating features. Beside the chemical and physical properties of the coating, its thickness is another important property which can influence the size, the shape and the overall magnetic behavior of the NPs system. In this work we propose a possible method to measure the thickness of the non-magnetic coating of core-shell MNPs through the use of controlled magnetization-magnetic force microscopy (CM-MFM). A preliminary study on the applicability of the proposed method has been performed on Fe3O4 NPs coated with a Cu film.

  14. Development of non-magnetic high manganese cryogenic steel for the construction of LHC project's superconducting magnet

    CERN Document Server

    Ozaki, Y; Kakihara, S; Shiraishi, M; Morito, N; Nohara, K

    2002-01-01

    High manganese steel (KHMN30L) as a cryogenic nonmagnetic material has been developed by Kawasaki Steel Corporation, which is designed for structural material for superconducting magnet in particle accelerator system. This steel satisfies the following requirements for the present use. 1) Low magnetic permeability: its relative magnetic permeability is lower than 1.002 throughout the range between 1.9 K and room temperature, and shows little temperature dependency which is the result of the highly elevated Neel temperature controlled by alloying composition design. 2) Low thermal expansion: its integrated contraction from room temperature to 4.2 K is as small as 0.18%. 3) Appropriate mechanical properties: yield strength and tensile strength can be adjusted to the desirable value by the manufacturing process condition without deteriorating physical properties. With these excellent properties, this steel is being supplied for nonmagnetic lamination of the cold mass of the LHC (Large Hadron Collider) supercondu...

  15. Design of Matched Zero-Index Metamaterials Using Non-Magnetic Inclusions in Epsilon-Near-Zero (ENZ) Media

    OpenAIRE

    Silveirinha, Mario; Engheta, Nader

    2006-01-01

    In this work, we study the electrodynamics of metamaterials that consist of resonant non-magnetic inclusions embedded in an epsilon-near-zero (ENZ) host medium. It is shown that the inclusions can be designed in such a way that both the effective permittivity and permeability of the composite structure are simultaneously zero. Two different metamaterial configurations are studied and analyzed in detail. For a particular class of problems, it is analytically proven that such matched zero-index...

  16. AN INVESTIGATION ON SOFT MAGNETIC AND NON-MAGNETIC MATERIALS UNDER LOW FREQUENCY FOR BIOMEDICAL SENSOR APPLICATION

    Directory of Open Access Journals (Sweden)

    Sheroz Khan

    2012-02-01

    Full Text Available In consequence of the recent development of magnetic sensors in biomedical sector, the investigation of magneticmaterials has been a contributing factor in application stage. This paper proposes a novel technique to investigate materials by obtaining unique distinctive impedance peaks with unique impedance values. A magneto-inductive sensoris used to measure the induction of magnetic and non-magnetic impedance peaks related to the change in permeability, thus characterizing the materials under low frequency.

  17. INDUCTION HEATING OF NON-MAGNETIC SHEET METALS IN THE FIELD OF A FLAT CIRCULAR MULTITURN SOLENOID

    Directory of Open Access Journals (Sweden)

    Y. Batygin

    2016-06-01

    Full Text Available The theoretical analysis of electromagnetic processes in the system for induction heating presented by a flat circular multiturn solenoid positioned above a plane of thin sheet non-magnetic metal has been conducted. The calculated dependences for the current induced in a metal sheet blank and ratio of transformation determined have been obtained. The maximal value of the transformation ratio with regard to spreading the eddy-currents over the whole area of the sheet metal has been determined.

  18. Cu, Pu and Fe high T{sub c} superconductors: Spin holes in anti-ferromagnetic clusters form nonmagnetic bipolarons

    Energy Technology Data Exchange (ETDEWEB)

    Wachter, Peter, E-mail: wachter@solid.phys.ethz.c [Laboratorium fuer Festkoerperphysik, ETH Zuerich, 8093 Zuerich (Switzerland)

    2009-03-15

    The new iron based high T{sub c} superconductors with T{sub c} up to 55 K have stirred new interest in this field. It is consensus that the BCS mechanism is not able to explain the high T{sub c}'s. In the following we propose that spin holes in anti-ferromagnetic clusters combine to make nonmagnetic bipolarons, which can condense and lead to superconductivity.

  19. Multiple-hopping trajectories near a rotating asteroid

    Science.gov (United States)

    Shen, Hong-Xin; Zhang, Tian-Jiao; Li, Zhao; Li, Heng-Nian

    2017-03-01

    We present a study of the transfer orbits connecting landing points of irregular-shaped asteroids. The landing points do not touch the surface of the asteroids and are chosen several meters above the surface. The ant colony optimization technique is used to calculate the multiple-hopping trajectories near an arbitrary irregular asteroid. This new method has three steps which are as follows: (1) the search of the maximal clique of candidate target landing points; (2) leg optimization connecting all landing point pairs; and (3) the hopping sequence optimization. In particular this method is applied to asteroids 433 Eros and 216 Kleopatra. We impose a critical constraint on the target landing points to allow for extensive exploration of the asteroid: the relative distance between all the arrived target positions should be larger than a minimum allowed value. Ant colony optimization is applied to find the set and sequence of targets, and the differential evolution algorithm is used to solve for the hopping orbits. The minimum-velocity increment tours of hopping trajectories connecting all the landing positions are obtained by ant colony optimization. The results from different size asteroids indicate that the cost of the minimum velocity-increment tour depends on the size of the asteroids.

  20. Contribution of afferent feedback and descending drive to human hopping

    DEFF Research Database (Denmark)

    Zuur, Abraham T.; Lundbye-Jensen, Jesper; Leukel, Christian

    2010-01-01

    to inhibit the motor cortex and this resulted in a suppression of the early EMG burst. These results suggest that sensory feedback and descending drive from the motor cortex are integrated to drive the motor neuron pool during the early EMG burst in hopping. Thus, simple reflexes work in concert with higher...

  1. Adaptive Resource Control in 2-hop Ad-Hoc Networks

    NARCIS (Netherlands)

    Yang, Y.; Heijenk, Gerhard J.; Haverkort, Boudewijn R.H.M.

    2009-01-01

    This paper presents a simple resource control mechanism with traffic scheduling for 2-hop ad-hoc networks, in which the Request-To-Send (RTS) packet is utilized to deliver feedback information. With this feedback information, the Transmission Opportunity (TXOP) limit of the sources can be controlled

  2. Young Children Manifest Spiritualities in Their Hip-Hop Writing

    Science.gov (United States)

    Norton, Nadjwa E. L.

    2014-01-01

    In this article, the author combines multicultural feminist critical theories with the voices of Black and Latina/Latino young spiritual children to extend culturally responsive teaching. The author illuminates how children use their hip-hop writing to construct themselves as people who communicate with God, choose spiritual content for their…

  3. Maroc-hop: music and youth identities in the Netherlands

    NARCIS (Netherlands)

    Gazzah, M.; Herrera, L.; Bayat, A.

    2010-01-01

    Two musical forms highly popular among youths of Moroccan origin in the Netherlands—Maroc-hop and Shaabi—permit youths to express specific and multiple identities in local contexts. Shaabi, a popular form of Moroccan folk music used to be found mainly in the private setting of family celebrations, m

  4. Hopping in a supercooled binary Lennard-Jones liquid

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Dyre, Jeppe

    1998-01-01

    A binary Lennard–Jones liquid has been investigated by molecular dynamics at equilibrium supercooled conditions. At the lowest temperature investigated, hopping is present in the system as indicated by a secondary peak in 4r2Gs(r,t), where Gs(r,t) is the van Hove self correlation function...

  5. Investigación a ritmo de hip-hop

    Directory of Open Access Journals (Sweden)

    Melisa Rivière

    2013-09-01

    Full Text Available Soñando se resiste. Hip-hop; en la calle y al parque. Varios autores. Alcaldía Mayor de Bogotá, Secretaría de Cultura, Recreación y Deporte, Orquesta Filarmónica de Bogotá, Bogotá, 2010, 180 págs.

  6. Impurity diffusion in a harmonic potential and nonhomogeneous temperature

    Science.gov (United States)

    Aragie, Berhanu; Asfaw, Mesfin; Demeyu, Lemi; Bekele, Mulugeta

    2014-09-01

    We propose different ways of manipulating the dispersion of impurities along a semiconductor layer during heat treatment. The impurities undergo a random walk assisted by a nonlinear harmonic potential and nonhomogeneous temperature. Depending on the strength of a hot spot, trap potential, impurity density and standard deviation of the hot spot, the impurities diffuse away from the central region and pile up around the peripheral region of the semiconductor layer. Furthermore, the numerical result depicts that the internal field at high doping level can be of sufficient strength to cause the broadening of the impurity profile.

  7. Power Radiated from ITER and CIT by Impurities

    Science.gov (United States)

    Cummings, J.; Cohen, S. A.; Hulse, R.; Post, D. E.; Redi, M. H.; Perkins, J.

    1990-07-01

    The MIST code has been used to model impurity radiation from the edge and core plasmas in ITER and CIT. A broad range of parameters have been varied, including Z{sub eff}, impurity species, impurity transport coefficients, and plasma temperature and density profiles, especially at the edge. For a set of these parameters representative of the baseline ITER ignition scenario, it is seen that impurity radiation, which is produced in roughly equal amounts by the edge and core regions, can make a major improvement in divertor operation without compromising core energy confinement. Scalings of impurity radiation with atomic number and machine size are also discussed.

  8. Hop pellets as an interesting source of antioxidant active compounds

    Directory of Open Access Journals (Sweden)

    Andrea Holubková

    2013-02-01

    Full Text Available Hop is a plant used by humankind for thousands of years. This plant is one of the main and indispensable raw materials for the beer production. It is used for various dishes preparation in the cuisine. Hop is also used to inhibit bacterial contamination. The hop extracts are used for its sedative, antiseptic and antioxidant properties in medicine, as a part of many phytopharmaceuticals. The present paper have focused on the extraction of polyphenolic compounds from 4 samples of hop pellets varieties of Aurora, Saaz, Lublin and Saphir, on the analyzing of bioactive substances (polyphenolics and flavonoids in prepared extracts and on the determination of antioxidant activity.  The highest content of polyphenolic substances was determined in the sample Lublin (153.06 mg gallic acid (GAE/g and Saaz (151.87 mg GAE/g. The amount of flavonoids in the samples  was descending order Saaz > Saphir > Aurora > Lublin. Hops, as plant, is known by high content of antioxidant active substances. Antioxidant activity was determined using three independent spectrofotometric methods, radical scavenging assays using 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS and 1,1-diphenyl-2-picrylhydrazyl (DPPH radical and ferric reducing antioxidant power (FRAP. The sample Aurora showed the highest ability to scavenge of ABTS radical cation. Antioxidant activity continued to decline in a row Saphir> Lublin> Saaz. The same trend was also observed by using the FRAP assay. The most effective DPPH radical scavengering activity had the sample Saaz a Saphir (p>0.05.doi:10.5219/270 Normal 0 21 false false false SK X-NONE X-NONE

  9. Decoherence and mode-hopping in spin-torque oscillators

    Science.gov (United States)

    Muduli, Pranaba

    2013-03-01

    A Spin Torque Oscillator (STO) is a nano-sized magneto-resistive device that can produce microwave signals in the GHz range as a result of spin transfer torque- a phenomena which is receiving increasing importance in contemporary spintronics research both for fundamental spin physics as well as a number of possible microwave applications e.g., oscillator, detectors and modulators. A very important question, both for fundamental physics as well for applications, is what limits the coherence time of the STO. This is a subject of significant interest recently. Until now theoretical studies have investigated decoherence through thermal noise assuming that only a single mode is excited. On the other hand, experiments clearly show both the existence of multiple modes and persistent mode-hopping between several modes. The impact on coherence time of such mode-hopping has been largely unexplored and a theoretical study of its origin is entirely lacking. In this work, we will present first ever systematic experimental investigations of mode hopping, and its impact on the coherence time in a magnetic tunnel junction based spin torque oscillator. We will discuss micromagnetic simulations and a theoretical treatment to show that the non-conservative fields due to finite damping-either positive or negative (spin torque) -couple individual modes and, in the presence of thermal noise, govern the experimentally observed mode-hopping. Using quantitative analysis of both coherence and dwell times, we will show that mode-hopping could be a limiting factor for STO coherence. Finally we show how our theoretical treatment can be extended to the case of a metallic nanocontact based STO, where anomalous temperature dependence of linewidth is found as result of the mode coupling. and Department of Physics, Indian Institute of Technology Delhi, New Delhi-110016, India

  10. Bound States in Boson Impurity Models

    Science.gov (United States)

    Shi, Tao; Wu, Ying-Hai; González-Tudela, A.; Cirac, J. I.

    2016-04-01

    The formation of bound states involving multiple particles underlies many interesting quantum physical phenomena, such as Efimov physics or superconductivity. In this work, we show the existence of an infinite number of such states for some boson impurity models. They describe free bosons coupled to an impurity and include some of the most representative models in quantum optics. We also propose a family of wave functions to describe the bound states and verify that it accurately characterizes all parameter regimes by comparing its predictions with exact numerical calculations for a one-dimensional tight-binding Hamiltonian. For that model, we also analyze the nature of the bound states by studying the scaling relations of physical quantities, such as the ground-state energy and localization length, and find a nonanalytical behavior as a function of the coupling strength. Finally, we discuss how to test our theoretical predictions in experimental platforms, such as photonic crystal structures and cold atoms in optical lattices.

  11. Extrinsic germanium Blocked Impurity Bank (BIB) detectors

    Science.gov (United States)

    Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.

    1989-01-01

    Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.

  12. Turbulent transport of impurities and their effect on energy confinement

    CERN Document Server

    Pusztai, I; Fulop, T; Candy, J

    2012-01-01

    By presenting linear and nonlinear gyrokinetic similarity studies, based on a balanced neutral beam injection deuterium discharge from the DIII-D tokamak, we demonstrate that impurities alter the scaling of the transport on the charge and mass of the main species, and even more importantly, they can dramatically change the energy transport even in relatively small quantities. A poloidally varying equilibrium electrostatic potential can lead to a strong reduction or sign change of the impurity peaking factor due to the combined effect of the in-out impurity density asymmetry and the EXB drift of impurities. We present an approximate expression for the impurity peaking factor and demonstrate that impurity peaking is not significantly affected by impurity self-collisions.

  13. Quantum Entanglement in the Two Impurity Kondo Model

    CERN Document Server

    Cho, S Y; Cho, Sam Young; Kenzie, Ross H. Mc

    2005-01-01

    In order to quantify quantum entanglement in two impurity Kondo systems, we calculate the concurrence, negativity, and von Neumann entropy. The entanglement of the two Kondo impurities is shown to be determined by two competing many-body effects, the Kondo effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, $I$. Due to the spin-rotational invariance of the ground state, the concurrence and negativity are uniquely determined by the spin-spin correlation between the impurities. It is found that there exists a critical minimum value of the antiferromagnetic correlation between the impurity spins which is necessary for entanglement of the two impurity spins. The critical value is discussed in relation with the unstable fixed point in the two impurity Kondo problem. Specifically, at the fixed point there is no entanglement between the impurity spins. Entanglement will only be created (and quantum information processing (QIP) be possible) if the RKKY interaction exchange energy, $I$, is at least severa...

  14. Communication: Proper treatment of classically forbidden electronic transitions significantly improves detailed balance in surface hopping.

    Science.gov (United States)

    Sifain, Andrew E; Wang, Linjun; Prezhdo, Oleg V

    2016-06-01

    Surface hopping is the most popular method for nonadiabatic molecular dynamics. Many have reported that it does not rigorously attain detailed balance at thermal equilibrium, but does so approximately. We show that convergence to the Boltzmann populations is significantly improved when the nuclear velocity is reversed after a classically forbidden hop. The proposed prescription significantly reduces the total number of classically forbidden hops encountered along a trajectory, suggesting that some randomization in nuclear velocity is needed when classically forbidden hops constitute a large fraction of attempted hops. Our results are verified computationally using two- and three-level quantum subsystems, coupled to a classical bath undergoing Langevin dynamics.

  15. Effect of impurities and processing on silicon solar cells. Volume 1: Characterization methods for impurities in silicon and impurity effects data base

    Science.gov (United States)

    Hopkins, R. H.; Davis, J. R.; Rohatgi, A.; Campbell, R. B.; Blais, P. D.; Rai-Choudhury, P.; Stapleton, R. E.; Mollenkopf, H. C.; Mccormick, J. R.

    1980-01-01

    Two major topics are treated: methods to measure and evaluate impurity effects in silicon and comprehensive tabulations of data derived during the study. Discussions of deep level spectroscopy, detailed dark I-V measurements, recombination lifetime determination, scanned laser photo-response, conventional solar cell I-V techniques, and descriptions of silicon chemical analysis are presented and discussed. The tabulated data include lists of impurity segregation coefficients, ingot impurity analyses and estimated concentrations, typical deep level impurity spectra, photoconductive and open circuit decay lifetimes for individual metal-doped ingots, and a complete tabulation of the cell I-V characteristics of nearly 200 ingots.

  16. Impurities: Curse and blessing for crystal growers

    Science.gov (United States)

    Fox, Donald K.; Mazelsky, R.

    1990-11-01

    The indespensability of high-quality source materials research and development has been established for many years. However, because contributors to this field are diverse and communication of research results is often fragmented, transfer of the new knowledge is very slow. This paper describes how increasing source purity has improved the quality of several crystals, and how the addition of controlled impurities has decreased the defect density in these crystals. Experimental evidence is presented in this paper.

  17. Removal of iron from impure graphites

    Energy Technology Data Exchange (ETDEWEB)

    Growcock, F.B.; Heiser, J.

    1979-01-01

    Iron-impregnated and ash-rich graphites have been purified by leaching with gaseous I/sub 2/ at 900/sup 0/C. With addition of H/sub 2/, the rate of removal of impurity iron can be markedly increased and becomes comparable to that obtained with Cl/sub 2/. I/sub 2/ has an advantage in that it can also volatilize Ca and perhaps Ba and Sr.

  18. Relationships between Xanthohumol and Polyphenol Content in Hop Leaves and Hop Cones with Regard to Water Supply and Cultivar

    Directory of Open Access Journals (Sweden)

    Veronika Abram

    2007-09-01

    Full Text Available The effect of water supply – especially of drought stress – on the content ofsome secondary metabolites in hops (Humulus lupulus L. was studied. The experimenttook place in 2006. Some relevant data from 2005 were included for comparison. Leavesand cones of nine hop cultivars grown under field conditions as well as in a pot experimentunder three water regimes were analyzed. The cultivars ranged from those most grown inSlovenia to promising crossbreed being tested. Leaves were sampled from July 18, 2006 toAugust 18, 2006, while cones were picked in the time of technological maturity. Standardanalytical methods were applied to determine the contents of xanthohumol, polyphenolsand α-acids in hop leaves and hop cones. The contents of the secondary metabolites inquestion depended more on the cultivar under investigation than on the water supply, atleast as far the growing conditions for a relatively normal development of the plant weremet.

  19. Design and testing of piezo motors for non-magnetic and/or fine positioning applications

    Science.gov (United States)

    Six, M. F.; Le Letty, R.; Seiler, R.; Coste, P.

    2005-07-01

    Piezoelectric motors offer several outstanding characteristics that may be very interesting for new scientific instruments in space applications. Piezo motors use a combination of electro-mechanical and frictional forces for generating a progressive motion; they are well suited for positioning applications because they exhibit a large force at rest without any power supply, and they often do not require any reduction gear. They are increasingly used in optical applications. Using piezo motors in space applications may become more and more relevant because of the continuous trend towards adaptive optics in future scientific payloads. In general, piezoelectric actuators are more and more used in space. Piezoelectric motors exhibit a number of advantages compared to conventional electromagnetic (stepping) motors, e.g. superior force/mass ratio, improved direct drive capability, no power supply to maintain a position, feasibility of a fully non-magnetic motor design. In this context, two complementary concepts have been designed and evaluated in the frame of ESA funded research and development activities: a resonant concept, called Rotary Piezo Actuator (RPA), a quasi-static concept, called Rotary Piezo Motor for High Precision Pointing (RPMHPP). The developed Rotary Piezo Actuator (RPA) is based on a Ultrasonic Piezo Drive (UPD) unit that drives a friction ring on the rotor part supported by a ball bearing assembly. This new motorization principle offers excellent motion dynamics and positioning accuracy combined with a high un-powered torque at standstill, and it does not rely on any magnetic features. A rotary piezo motor compliant with the requirements of a reference space application has been designed and tested. The technology remains challenging to be mastered, since the interdisciplinary aspects of the concept include, among others, drive electronics and controller design, piezo-electricity, contact mechanics and tribology. The conceptual design has lead to a

  20. Characteristics of impurity-induced pseudogap

    Energy Technology Data Exchange (ETDEWEB)

    Numata, Yoshinori, E-mail: yo_c.n-15@ruri.waseda.jp; Uto, Tatsuro; Matuda, Azusa

    2016-05-15

    Highlights: • We have studied characteristics of the pseudogap states of Co substituted Bi2212 crystals used by STM/STS. • The pseudogap of Co 4% samples have temperature dependence. • We observed a disappearance of a 4a periodic modulation and a development of 1D modulation in the DOS. • An intimate relation between the DOS modulation and the pseudogap is confirmed. - Abstract: We have performed STM/STS measurements on a single crystal of Bi{sub 2.1}Sr{sub 1.9}Ca (Cu{sub 1−x}Co{sub x}) {sub 2}O{sub 8+δ} (Co-Bi2212), to reveal impurity effects on the pseudogap in cuprate high-T{sub c} superconductors. We report a drastic change in the temperature dependence of a pseudogap and in the density of states (DOS) modulation with a 4a period, in a certain doping range. In the Co 4% substituted samples, the pseudogap gradually closed like a gap of a BCS superconductor for slightly overdoped and overdoped regime, while their low temperature values were enhanced due to impurity. In addition, a disappearance of a 4a periodic modulation and a development of new modulation were observed in the DOS spatial distribution. These results indicate an intimate relation between the DOS modulation and the pseudogap, and qualitative difference in the impurity enhanced pseudogap and conventional one.

  1. Electrophobic interaction induced impurity clustering in metals

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Hong-Bo; Wang, Jin-Long; Jiang, W.; Lu, Guang-Hong; Aguiar, J. A.; Liu, Feng

    2016-10-01

    We introduce the concept of electrophobic interaction, analogous to hydrophobic interaction, for describing the behavior of impurity atoms in a metal, a 'solvent of electrons'. We demonstrate that there exists a form of electrophobic interaction between impurities with closed electron shell structure, which governs their dissolution behavior in a metal. Using He, Be and Ar as examples, we predict by first-principles calculations that the electrophobic interaction drives He, Be or Ar to form a close-packed cluster with a clustering energy that follows a universal power-law scaling with the number of atoms (N) dissolved in a free electron gas, as well as W or Al lattice, as Ec is proportional to (N2/3-N). This new concept unifies the explanation for a series of experimental observations of close-packed inert-gas bubble formation in metals, and significantly advances our fundamental understanding and capacity to predict the solute behavior of impurities in metals, a useful contribution to be considered in future material design of metals for nuclear, metallurgical, and energy applications.

  2. Hop Weighted DV-Hop Localization Algorithm%跳数加权DV-Hop定位算法

    Institute of Scientific and Technical Information of China (English)

    刘凯; 余君君; 谭立雄

    2012-01-01

    A beacon node selection scheme and a DV-Hop localization algorithm based on hop weighted are proposed to improve the positioning performance in this paper. First of all, by setting a threshold value of signal propagation hop,the beacon nodes whose propagation hop are fewer are retained. Then,a beacon node optimization is followed to eliminate unfavourable beacon nodes which are approximately in a line to avoid positioning failure. Besides, based on the relationship between distance estimation error and signal propagation hop derived from Friis model,the hop weighted localization algorithm is obtained. It uses the signal propagation hop as the weighted factors to modify the positioning result that gained through maximum likelihood estimation, which reduces the effect on positioning accuracy brought by distance estimation error. The simulation results show that the proposed method can improve the positioning accuracy by 3% ~5%.%针对DV-Hop定位算法中距离估计误差对定位结果的影响,提出了一种信标节点优选方案和跳数加权DV-Hop定位算法.首先通过设定跳数阈值,保留跳数较少的信标节点,然后剔除近似在一条直线上的信标节点,完成信标节点优选,避免未知节点无法定位的情形.此外,利用Friis模型推导出距离估计误差与信号传播跳数之间的映射关系,采用传播跳数作为加权因子对定位结果进行了修正.仿真结果表明该算法降低了距离估计误差对定位精度的影响,提高了定位精度.

  3. Effect of stellar wind induced magnetic fields on planetary obstacles of non-magnetized hot Jupiters

    Science.gov (United States)

    Erkaev, N. V.; Odert, P.; Lammer, H.; Kislyakova, K. G.; Fossati, L.; Mezentsev, A. V.; Johnstone, C. P.; Kubyshkina, D. I.; Shaikhislamov, I. F.; Khodachenko, M. L.

    2017-10-01

    We investigate the interaction between the magnetized stellar wind plasma and the partially ionized hydrodynamic hydrogen outflow from the escaping upper atmosphere of non-magnetized or weakly magnetized hot Jupiters. We use the well-studied hot Jupiter HD 209458b as an example for similar exoplanets, assuming a negligible intrinsic magnetic moment. For this planet, the stellar wind plasma interaction forms an obstacle in the planet's upper atmosphere, in which the position of the magnetopause is determined by the condition of pressure balance between the stellar wind and the expanded atmosphere, heated by the stellar extreme ultraviolet radiation. We show that the neutral atmospheric atoms penetrate into the region dominated by the stellar wind, where they are ionized by photoionization and charge exchange, and then mixed with the stellar wind flow. Using a 3D magnetohydrodynamic (MHD) model, we show that an induced magnetic field forms in front of the planetary obstacle, which appears to be much stronger compared to those produced by the solar wind interaction with Venus and Mars. Depending on the stellar wind parameters, because of the induced magnetic field, the planetary obstacle can move up to ≈0.5-1 planetary radii closer to the planet. Finally, we discuss how estimations of the intrinsic magnetic moment of hot Jupiters can be inferred by coupling hydrodynamic upper planetary atmosphere and MHD stellar wind interaction models together with UV observations. In particular, we find that HD 209458b should likely have an intrinsic magnetic moment of 10-20 per cent that of Jupiter.

  4. Immunomodulation by the Pseudomonas syringae HopZ type III effector family in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Jennifer D Lewis

    Full Text Available Pseudomonas syringae employs a type III secretion system to inject 20-30 different type III effector (T3SE proteins into plant host cells. A major role of T3SEs is to suppress plant immune responses and promote bacterial infection. The YopJ/HopZ acetyltransferases are a superfamily of T3SEs found in both plant and animal pathogenic bacteria. In P. syringae, this superfamily includes the evolutionarily diverse HopZ1, HopZ2 and HopZ3 alleles. To investigate the roles of the HopZ family in immunomodulation, we generated dexamethasone-inducible T3SE transgenic lines of Arabidopsis for HopZ family members and characterized them for immune suppression phenotypes. We show that all of the HopZ family members can actively suppress various facets of Arabidopsis immunity in a catalytic residue-dependent manner. HopZ family members can differentially suppress the activation of mitogen-activated protein (MAP kinase cascades or the production of reactive oxygen species, whereas all members can promote the growth of non-virulent P. syringae. Localization studies show that four of the HopZ family members containing predicted myristoylation sites are localized to the vicinity of the plasma membrane while HopZ3 which lacks the myristoylation site is at least partially nuclear localized, suggesting diversification of immunosuppressive mechanisms. Overall, we demonstrate that despite significant evolutionary diversification, all HopZ family members can suppress immunity in Arabidopsis.

  5. The impact of hop bitter acid and polyphenol profiles on the perceived bitterness of beer.

    Science.gov (United States)

    Oladokun, Olayide; Tarrega, Amparo; James, Sue; Smart, Katherine; Hort, Joanne; Cook, David

    2016-08-15

    Thirty-four commercial lager beers were analysed for their hop bitter acid, phenolic acid and polyphenol contents. Based on analytical data, it was evident that the beers had been produced using a range of different raw materials and hopping practices. Principal Components Analysis was used to select a sub-set of 10 beers that contained diverse concentrations of the analysed bitter compounds. These beers were appraised sensorially to determine the impacts of varying hop acid and polyphenolic profiles on perceived bitterness character. Beers high in polyphenol and hop acid contents were perceived as having 'harsh' and 'progressive' bitterness, whilst beers that had evidently been conventionally hopped were 'sharp' and 'instant' in their bitterness. Beers containing light-stable hop products (tetrahydro-iso-α-acids) were perceived as 'diminishing', 'rounded' and 'acidic' in bitterness. The hopping strategy adopted by brewers impacts on the nature, temporal profile and intensity of bitterness perception in beer.

  6. Motion of a Distinguishable Impurity in the Bose Gas: Arrested Expansion Without a Lattice and Impurity Snaking

    Science.gov (United States)

    Robinson, Neil J.; Caux, Jean-Sébastien; Konik, Robert M.

    2016-04-01

    We consider the real-time dynamics of an initially localized distinguishable impurity injected into the ground state of the Lieb-Liniger model. Focusing on the case where integrability is preserved, we numerically compute the time evolution of the impurity density operator in regimes far from analytically tractable limits. We find that the injected impurity undergoes a stuttering motion as it moves and expands. For an initially stationary impurity, the interaction-driven formation of a quasibound state with a hole in the background gas leads to arrested expansion—a period of quasistationary behavior. When the impurity is injected with a finite center-of-mass momentum, the impurity moves through the background gas in a snaking manner, arising from a quantum Newton's cradlelike scenario where momentum is exchanged back and forth between the impurity and the background gas.

  7. Density of states of the one-dimensional electron gas: Impurity levels, impurity bands, and the band tail

    Science.gov (United States)

    Gold, A.; Ghazali, A.

    1994-06-01

    The density of states of cylindrical quantum wires is calculated in the presence of charged impurities located in the center of the wire. A multiple-scattering approach (Klauder's fifth approximation), which represents a self-consistent t-matrix approximation, is used. For small impurity densities and in the weak screening limit the ground-state impurity band and four excited-state impurity bands are obtained within our approach. We find good agreement between the numerically obtained spectral densities with the corresponding analytical spectral densities calculated with the single-impurity wave functions. The merging of impurity bands is studied. For large impurity densities we obtain a band tail. We present an analytical expression for the disorder-induced renormalized band-edge energy in the band-tail regime.

  8. Hip-Hop Guayaquil: culturas viajeras e identidades locales

    Directory of Open Access Journals (Sweden)

    1999-01-01

    Full Text Available HIP-HOP GUAYAQUIL: CULTURES ITINÉRANTES ET IDENTITES LOCALES. Le hip-hop est un style de musique contemporaine caractérisé par une orchestration d’œuvres lyriques rapées, la superposition de morceaux de musique enregistrés dans le passé par différents artistes, et une instrumentation électronique, tout cela sur des rythmes de basse réguliers et constants. Le hip-hop, musique accompagnée de ses propres danses et de sa mode, est le produit du déplacement et de la transformation d’une variété d’idéologies politiques de la communauté noire qui se constituent à partir de relations qui se modifient entre elles, et en relation avec les cultures dominantes contre lesquelles elles luttent quotidiennement. À l’origine, le hip-hop est lié à des mouvements d’identité de jeunes noirs. Dans cet article, il est intéressant d’étudier le rôle du hip-hop dans la formulation d’une identité entre jeunes métisses et noirs des secteurs populaires de Guayaquil. Cet exemple illustre la nécessité d’inclure dans l’analyse les dimensions politiques des processus de traduction du global au niveau local. El hip-hop es un género de música contemporánea caracterizado por la orquestación de líricas que son rapeadas, superposición de fragmentos de música grabada en el pasado por diferentes artistas, e instrumentación electrónica, todo ello sobre ritmos de bajo regulares y constantes. Como un tipo de música acompañado por sus propias formas de danza y moda, el hip-hop es producto del viaje y la transformación de una variedad de ideologías políticas de la comunidad negra que se constituyen a sí mismas en relaciones cambiantes entre sí y en relación a las culturas dominantes contra las cuales luchan cotidianamente. El hip-hop está ligado, en su contexto originario, a políticas de identidad defendidas por jóvenes negros. Lo que interesa explorar en este artículo es el papel del hip-hop en la formulación de una identidad

  9. Robust room temperature ferromagnetism and band gap tuning in nonmagnetic Mg doped ZnO films

    Science.gov (United States)

    Quan, Zhiyong; Liu, Xia; Qi, Yan; Song, Zhilin; Qi, Shifei; Zhou, Guowei; Xu, Xiaohong

    2017-03-01

    Mg doped ZnO films with hexagonal wurtzite structure were deposited on c-cut sapphire Al2O3 substrates by pulsed laser deposition. Both room temperature ferromagnetism and band gap of the films simultaneously tuned by the concentration of oxygen vacancies were performed. Our results further reveal that the singly occupied oxygen vacancies should be responsible for the room temperature ferromagnetism and band gap narrowing. Singly occupied oxygen vacancies having the localized magnetic moments form bound magnetic polarons, which results in a long-range ferromagnetic ordering due to Mg doping. Moreover, band gap narrowing of the films is probably due to the formation of impurity band in the vicinity of valence band, originating from singly occupied oxygen vacancies. These results may build a bridge to understand the relationship between the magnetic and optical properties in oxide semiconductor, and are promising to integrate multiple functions in one system.

  10. Influence of the constituent alpha acids of Ukrainian varieties of hops and hop preparations on quality indicators of mash and beer

    Directory of Open Access Journals (Sweden)

    L. Protsenko

    2015-05-01

    Full Text Available Introduction. The aim of the study is to establish the dependence of the bitterness of mash and the beer intoxication on the quality and quantity of the homologues of alpha acids in the Ukrainian varieties of hops, and on the content of cohumulone in alpha acids in particular. Materials and methods.Aromatic and bitter hop sorts of Ukrainian selection with different content of cohumulone in alpha-acids were investigated and so was the beer, made of these components. High performance liquid chromatography (HPLC was used to determine the amount and composition of bitter hop substances and their transformation products in the brewing process; also there were spectrophotometric methods for quality control of bitterness of hopped mash and finished beer in use. Results and discussion. The composition of bitter substances of aromatic and bitter hop sorts of Ukrainian selection was analyzed and so the beer, made of them. It was noted that the alpha-acids of the analyzed sorts incorporate a wide range of cohumulone content rated from 16.7% in the Kumyr sort to 44,1% in the Ruslan sort. The dependences between the quality and quantity of the bitter hop sorts and bitterness and quality of hopped mash and beer were established. The content of cohumulone in alphaacids of hops has to be less than 28% to obtain quality bitter beer. The role of the beta-acid compoundsin the formation of bitter mash, hopped with aroma hop varieties with a ratio of beta to alpha acids acids around one, is much more important compared to the bitter varieties. Conclusions. The conducted researches show that in applying the bitter hops with different compositon of alphaacids for mash intoxication, this usage is more effective in the sorts that have a large content of cohumulone.

  11. Structural Identification and Characterization of Potential Impurities of Azelnidipine

    Directory of Open Access Journals (Sweden)

    Sureshbabu Kapavarapu

    2016-06-01

    Full Text Available Azelnidipine (AZL is a pale yellowish white tablet (16mg with diameter of 9.2mm and thickness of 3.3mm. A reverse phase performance liquid chromatographic method was developed for the determination of AZL in bulk and pharmaceutical dosage form. During the synthesis of bulk drug of AZL, we observed four impurities. All the impurities were detected by a gradient high performance liquid chromatographic (HPLC method. LC-MS was performed to identify the mass number of these impurities. A thorough study was carried out to characterize the impurities. These impurities were synthesized, characterized and were co-injected with the sample containing impurities and are found to be matching with the impurities present in the sample. Based on the complete spectral analysis (UV, IR, NMR and MS these impurities were characterized as 1 Azelnidipine Stage-I para impurity [Impurity 1], whose molecular formula is C14 H15 NO5 and molecular weight is 277.27, 2 Azelnidipine Intermediate [Impurity 2], whose molecular formula is C14H15NO5 and molecular weight is 277.27, 3 4-Nitro Azelnidipine [Impurity 3], whose molecular formula is C33H34N4O6 and molecular weight is 582.65 and, 4 2-Nitro Azelnidipine [Impurity 4], whose molecular formula is C33H34N4O6 and molecular weight is 582.65. The proposed method was validated as per International Conference on Harmonization (ICH guidelines. The method was accurate, precise, specific and rapid found to be suitable for the quantitative analysis of the drug and dosage form.

  12. Fast frequency hopping codes applied to SAC optical CDMA network

    Science.gov (United States)

    Tseng, Shin-Pin

    2015-06-01

    This study designed a fast frequency hopping (FFH) code family suitable for application in spectral-amplitude-coding (SAC) optical code-division multiple-access (CDMA) networks. The FFH code family can effectively suppress the effects of multiuser interference and had its origin in the frequency hopping code family. Additional codes were developed as secure codewords for enhancing the security of the network. In considering the system cost and flexibility, simple optical encoders/decoders using fiber Bragg gratings (FBGs) and a set of optical securers using two arrayed-waveguide grating (AWG) demultiplexers (DeMUXs) were also constructed. Based on a Gaussian approximation, expressions for evaluating the bit error rate (BER) and spectral efficiency (SE) of SAC optical CDMA networks are presented. The results indicated that the proposed SAC optical CDMA network exhibited favorable performance.

  13. Dielectric relaxation and hopping conduction in reduced graphite oxide

    Science.gov (United States)

    Wei, Guidan; Yu, Ji; Gu, Min; Tang, Tong B.

    2016-06-01

    Graphite oxide reduced by sodium borohydride was characterised and its electrical conduction investigated with impedance spectroscopy. Thermal dependence of electrical modulus (instead of permittivity, its inverse) was calculated from complex impedance spectra, an approach that prevents any peak in dielectric loss (imaginary component) from being swarmed by large dc conductivity. Two loss peaks appeared at each tested frequency, in a sample of either degree of reduction. The set of weaker peak should arise from the relaxation of some polar bonds, as proposed earlier by us. The stronger loss peaks may correspond to the hopping of conduction electrons; variable range hopping is also consistent with the observed thermal dependence of conductivity. However, nearer ambient temperature there is a change in mechanism, to band transport, with an activation energy of fairly similar values as derived from both loss peaks and conductivity.

  14. O CIRCUITO HIP HOP NA REGIÃO DE CAMPINAS

    Directory of Open Access Journals (Sweden)

    Cristiano Nunes Alves

    2013-01-01

    Full Text Available This paper examines the thickness of the circuit hip hop in the region of Campinas and it’s a part of an inventory made in fifteen cities of the region, between 2003 and 2005. The circuit hip hop growing in Campinas since the decade of 1980, and has been expanding in the context of urbanization and metropolis. We noticed some residual cultural component in places involves, among others, the alternative production involved by a technically and territorial division of labor spurred by circuits upside of information. The culture of the streets and these circuits, survive to the urban division and fragmentation. It is, therefore, a study of the region of Campinas as a place that houses technical, informational and communicational densities. We analyzed geographical conditions of contemporary life in this region, inquiring about the communication and the informational components in the use of the territory.

  15. Hip-Hop:屁股不会说谎

    Institute of Scientific and Technical Information of China (English)

    董乐

    2006-01-01

    <正> Hip 是屁股,Hop 是跳跃的意思,中文习惯称为"嘻哈"。Hip-Hop 是指一种20世纪70年代末产生于美国街头的黑人文化,主要流行于纽约的南布郎士、布鲁克林区等一些黑人贫困地区。它包括音乐、舞蹈、涂鸦、刺青和衣着,但更重要的是精神,是"嬉笑怒骂"。这一切源于对真实的追求与对

  16. Hip-Hop(e): The Cultural Practice and Critical Pedagogy of International Hip-Hop. Adolescent Cultures, School, and Society. Volume 56

    Science.gov (United States)

    Porfilio, Brad J., Ed.; Viola, Michael J., Ed.

    2012-01-01

    Illuminating hip-hop as an important cultural practice and a global social movement, this collaborative project highlights the emancipatory messages and cultural work generated by the organic intellectuals of global hip-hop. Contributors describe the social realities--globalization, migration, poverty, criminalization, and racism--youth are…

  17. New hop (Humulus lupulus L. cultivars from Romania

    Directory of Open Access Journals (Sweden)

    Alexandru SALONTAI

    1985-08-01

    Full Text Available The research staff of the Agronomy Institute of Cluj-Napoca breeded the first Romanian hop cultivars officially approved in 1984 by the State Commission for the Testing and Approval of Plant Varieties. The new Humulus lupulus varieties are cv. "Napoca'l", cv. "Aroma" and cv. "Transilvania". The selection method, origin, biological characteristics, productivity and some technological qualities of the new cultivars are discussed in the paper.

  18. HPLC Analysis of alpha and beta Acids in Hops

    Energy Technology Data Exchange (ETDEWEB)

    Danenhower, Travis [Kutztown University; Force, Leyna [Kutztown University; Petersen, Kenneth [Kutztown University; Betts, Thomas [Kutztown University; Baker, Gary A [ORNL

    2008-01-01

    Early in brewing history, a variety of herbs and spices (such as coriander, rosemary, yarrow, and bog myrtle) were used to flavor beer (1). It is evident, from the Bavarian Purity Law of 1516, that a major shift in beer flavoring occurred around the middle of the second millennium. This law declared that only three ingredients could be used to brew beer: barley, water, and hops (1), thus eliminating other spices from German beer. (The importance of yeast had not yet been uncovered.)

  19. Implementation of Low Power Multi-hop Wireless Sensor Network

    OpenAIRE

    Zhou Jianhong; Ma Maode; Fengyong

    2016-01-01

    In this paper, the multi-hop wireless sensor network is created, which is realized by Micaz and Mib520 Board using TinyOS and Cygwin. The mote transmission mode is engaged and off-the-shelf protocols and algorithm, RSSI and PDR, are applied in this wireless network and the performance is improved. Several experiments are proposed to set standard RSSI threshold value to allow the user to send packet with efficient power level.

  20. 多维性感之Hip-Hop

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    “奥尼尔说他是NBA历史上最有统治力量的,他错了,现在统治NBA的是Hip-Hop,我的会员们都有数十年的NBA现场观战经验,而现在他们对NBA的概念就是,‘这是个恶棍联盟’”

  1. 时尚活力的Hip-hop

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    什么是Hip-hop Hip-hop起源于上世纪70年代中期的美国纽约,这个词语已经成为新生代族群的代名词。Hip-hop不是一个时代的热潮,它是一种感染了一代又一代的文化。总的来说Hip-hop是Hip-hop文化的统

  2. HIP HOP: A CORPORAL PRACTICE (EXPRESSION) THAT TERRITORIALIZE MEDELLIN CITY

    OpenAIRE

    Hincapié, Astrid

    2014-01-01

    This article is part of the research Appropriation of dancing urban corporal practices by young people of the city of Medellin – Commune 13 (Col.), which was developed in the master in Motricity and human development of the University of Antioquia. In this article we analyze, through an urban ethnography, how young people from the city create a cultural territory by practicing Hip-Hop. An artistic expression that develops in the middle of the tensions that takes place among young people, inst...

  3. Understanding hopping transport and thermoelectric properties of conducting polymers

    OpenAIRE

    Ihnatsenka, Siarhei; Crispin, Xavier; Zozoulenko, Igor

    2015-01-01

    We calculate the conductivity sigma and the Seebeck coefficient S for the phonon-assisted hopping transport in conducting polymers poly(3,4-ethylenedioxythiophene) or PEDOT, experimentally studied by Bubnova et al. [J. Am. Chem. Soc. 134, 16456 (2012)]. We use the Monte Carlo technique as well as the semianalytical approach based on the transport energy concept. We demonstrate that both approaches show a good qualitative agreement for the concentration dependence of sigma and S. At the same t...

  4. Hsp70/Hsp90 organising protein (hop): beyond interactions with chaperones and prion proteins.

    Science.gov (United States)

    Baindur-Hudson, Swati; Edkins, Adrienne L; Blatch, Gregory L

    2015-01-01

    The Hsp70/Hsp90 organising protein (Hop), also known as stress-inducible protein 1 (STI1), has received considerable attention for diverse cellular functions in both healthy and diseased states. There is extensive evidence that intracellular Hop is a co-chaperone of the major chaperones Hsp70 and Hsp90, playing an important role in the productive folding of Hsp90 client proteins. Consequently, Hop is implicated in a number of key signalling pathways, including aberrant pathways leading to cancer. However, Hop is also secreted and it is now well established that Hop also serves as a receptor for the prion protein, PrP(C). The intracellular and extracellular forms of Hop most likely represent two different isoforms, although the molecular determinants of these divergent functions are yet to be identified. There is also a growing body of research that reports the involvement of Hop in cellular activities that appear independent of either chaperones or PrP(C). While Hop has been shown to have various cellular functions, its biological function remains elusive. However, recent knockout studies in mammals suggest that Hop has an important role in embryonic development. This review provides a critical overview of the latest molecular, cellular and biological research on Hop, critically evaluating its function in healthy systems and how this function is adapted in diseases states.

  5. Changes in the hop-derived volatile profile upon lab scale boiling.

    Science.gov (United States)

    Praet, Tatiana; Van Opstaele, Filip; Steenackers, Bart; De Brabanter, Joseph; De Vos, Dirk; Aerts, Guido; De Cooman, Luc

    2015-09-01

    Hop terpenes might be oxidized during kettle boiling into more water soluble compounds that could contribute to 'hoppy' aroma of kettle hopped lager beers. Our current research proves that the boiling process induces significant changes in the hop oil volatile profile. The discrimination between volatile profiles of unboiled and boiled hop essential oil was evaluated via principal component and cluster analysis (PCA and CA). HS-SPME-GC-MS analysis revealed quantitative changes (e.g. increases in the levels of oxygenated α-humulene and β-caryophyllene derivatives) as well as qualitative changes (i.e. detection of compounds, not found in unboiled hop essential oil) in the hop oil volatile profile upon boiling. Many of these compounds were previously found in lager beer and may therefore contribute to beer flavor. Interestingly, the analytical difference between unboiled and boiled hop essential oil proved to be more pronounced as the initial hop essential oil concentration used for boiling was increased. In addition, lager beers spiked with boiled hop oil were described as 'hoppy/spicy' during sensory evaluations. Therefore, the newly formed products and hop oil constituents that are characterized by an increased recovery after boiling, are candidate compounds for 'hoppy' aroma in real brewing practice. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Lack of association between gastric cancer and hopQ alleles in Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    Kazemi Elham

    2016-01-01

    Full Text Available Helicobacter pylori use a number of mechanisms to survive in the stomach lumen. The presence of these bacteria in the stomach can lead to gastritis and reduction in stomach acid production. Acute inflammation can directly damage to the peripheral cells that are responsible for the secretion of acid. The risk of developing gastric carcinoma is associated to heterogeneity of Helicobacter pylori virulence factors (such as cagA. The HopQ is one of the outer membrane proteins involved in bacterial adherence to gastric mucosa and has been suggested to also play a role in the virulence of H. pylori. This gene has been shown in two types. The purpose of the current study was to investigate the association between different H. pylori virulence hopQ alleles (types I and II and patients with gastroduodenal disorders. For this purpose 58 stomach biopsies the of patients with gastric cancer and 100 saliva samples from healthy individuals were collected. Then genomic DNA was purified and PCR for was done for desired genes via specific primers. The H. pylori infections were diagnosed by PCR for GlmM gene. Then frequencies of hopQI+, hopQII+ and hopQI+ hopQII+ genotypes were determined in H. pylori infected cases. Statistical analysis showed that there were not significant differences between healthy and diseased ones for genotypes hopQI+, hopQII+ and hopQI+ hopQII+.

  7. Dynamics of impurities in a three-dimensional volume-preserving map.

    Science.gov (United States)

    Das, Swetamber; Gupte, Neelima

    2014-07-01

    We study the dynamics of inertial particles in three-dimensional incompressible maps, as representations of volume-preserving flows. The impurity dynamics has been modeled, in the Lagrangian framework, by a six-dimensional dissipative bailout embedding map. The fluid-parcel dynamics of the base map is embedded in the particle dynamics governed by the map. The base map considered for the present study is the Arnold-Beltrami-Childress (ABC) map. We consider the behavior of the system both in the aerosol regime, where the density of the particle is larger than that of the base flow, as well as the bubble regime, where the particle density is less than that of the base flow. The phase spaces in both the regimes show rich and complex dynamics with three types of dynamical behaviors--chaotic structures, regular orbits, and hyperchaotic regions. In the one-action case, the aerosol regime is found to have periodic attractors for certain values of the dissipation and inertia parameters. For the aerosol regime of the two-action ABC map, an attractor merging and widening crisis is identified using the bifurcation diagram and the spectrum of Lyapunov exponents. After the crisis an attractor with two parts is seen, and trajectories hop between these parts with period 2. The bubble regime of the embedded map shows strong hyperchaotic regions as well as crisis induced intermittency with characteristic times between bursts that scale as a power law behavior as a function of the dissipation parameter. Furthermore, we observe a riddled basin of attraction and unstable dimension variability in the phase space in the bubble regime. The bubble regime in the one-action case shows similar behavior. This study of a simple model of impurity dynamics may shed light upon the transport properties of passive scalars in three-dimensional flows. We also compare our results with those seen earlier in two-dimensional flows.

  8. Exact solution of a t-J chain with impurity

    Energy Technology Data Exchange (ETDEWEB)

    Beduerftig, G. [Hannover Univ. (Germany). Inst. fuer Theoretische Physik; Essler, F.H.L. [Oxford Univ. (United Kingdom). Dept. of Theoretical Physics; Frahm, H. [Hannover Univ. (Germany). Inst. fuer Theoretische Physik

    1997-04-07

    We study the effects of an integrable impurity in a periodic t-J chain. The impurity couples to both spin and charge degrees of freedom and has the interesting feature that the interaction with the bulk can be varied continuously without losing integrability. We first consider ground state properties close to half-filling in the presence of a small bulk magnetic field. We calculate the impurity contributions to the (zero-temperature) susceptibilities and the low-temperature specific heat and determine the high-temperature characteristics of the impurity. We then investigate transport properties by computing the spin and charge stiffnesses at zero temperature. Finally the impurity phase shifts are calculated and the existence of an impurity bound state in the holon sector is established. (orig.).

  9. Magnetic states of single impurity in disordered environment

    Directory of Open Access Journals (Sweden)

    G.W. Ponedilok

    2013-01-01

    Full Text Available The charged and magnetic states of isolated impurities dissolved in amorphous metallic alloy are investigated. The Hamiltonian of the system under study is the generalization of Anderson impurity model. Namely, the processes of elastic and non-elastic scattering of conductive electrons on the ions of a metal and on a charged impurity are included. The configuration averaged one-particle Green's functions are obtained within Hartree-Fock approximation. A system of self-consistent equations is given for calculation of an electronic spectrum, the charged and the spin-polarized impurity states. Qualitative analysis of the effect of the metallic host structural disorder on the observed values is performed. Additional shift and broadening of virtual impurity level is caused by a structural disorder of impurity environment.

  10. Impurity binding energy for -doped quantum well structures

    Indian Academy of Sciences (India)

    V Tulupenko; C A Duque; R Demediuk; O Fomina; V Akimov; V Belykh; T Dmitrichenko; V Poroshin

    2014-10-01

    The binding energy of an impurity delta layer situated either in the centre or at the edge of a quantum well (QW) is theoretically considered for the example of -type Si0.8Ge0.2/Si/Si0.8Ge0.2 QW doped with phosphorus. Calculations are made for the case of not so big impurity concentrations, when impurity bands are not yet formed and it is still possible to treat impurity as isolated ones. It is shown on the base of self-consistent solution of Schrödinger, Poisson and electro-neutrality equations that impurity binding energy is dependent on the degree of impurity ionization and the most noticeably for the case of edge-doped QWs.

  11. Transitions and excitations in a superfluid stream passing small impurities

    KAUST Repository

    Pinsker, Florian

    2014-05-08

    We analyze asymptotically and numerically the motion around a single impurity and a network of impurities inserted in a two-dimensional superfluid. The criticality for the breakdown of superfluidity is shown to occur when it becomes energetically favorable to create a doublet—the limiting case between a vortex pair and a rarefaction pulse on the surface of the impurity. Depending on the characteristics of the potential representing the impurity, different excitation scenarios are shown to exist for a single impurity as well as for a lattice of impurities. Depending on the lattice characteristics it is shown that several regimes are possible: dissipationless flow, excitations emitted by the lattice boundary, excitations created in the bulk, and the formation of large-scale structures.

  12. HOP expression is regulated by p53 and RAS and characteristic of a cancer gene signature.

    Science.gov (United States)

    Mattison, Stacey A; Blatch, Gregory L; Edkins, Adrienne L

    2017-03-01

    The Hsp70/Hsp90 organising protein (HOP) is a co-chaperone essential for client protein transfer from Hsp70 to Hsp90 within the Hsp90 chaperone machine. Although HOP is upregulated in various cancers, there is limited information from in vitro studies on how HOP expression is regulated in cancer. The main objective of this study was to identify the HOP promoter and investigate its activity in cancerous cells. Bioinformatic analysis of the -2500 to +16 bp region of the HOP gene identified a large CpG island and a range of putative cis-elements. Many of the cis-elements were potentially bound by transcription factors which are activated by oncogenic pathways. Luciferase reporter assays demonstrated that the upstream region of the HOP gene contains an active promoter in vitro. Truncation of this region suggested that the core HOP promoter region was -855 to +16 bp. HOP promoter activity was highest in Hs578T, HEK293T and SV40- transformed MEF1 cell lines which expressed mutant or inactive p53. In a mutant p53 background, expression of wild-type p53 led to a reduction in promoter activity, while inhibition of wild-type p53 in HeLa cells increased HOP promoter activity. Additionally, in Hs578T and HEK293T cell lines containing inactive p53, expression of HRAS increased HOP promoter activity. However, HRAS activation of the HOP promoter was inhibited by p53 overexpression. These findings suggest for the first time that HOP expression in cancer may be regulated by both RAS activation and p53 inhibition. Taken together, these data suggest that HOP may be part of the cancer gene signature induced by a combination of mutant p53 and mutated RAS that is associated with cellular transformation.

  13. Duplex Schemes in Multiple Antenna Two-Hop Relaying

    Directory of Open Access Journals (Sweden)

    Anja Klein

    2008-04-01

    Full Text Available A novel scheme for two-hop relaying defined as space division duplex (SDD relaying is proposed. In SDD relaying, multiple antenna beamforming techniques are applied at the intermediate relay station (RS in order to separate downlink and uplink signals of a bi-directional two-hop communication between two nodes, namely, S1 and S2. For conventional amplify-and-forward two-hop relaying, there appears a loss in spectral efficiency due to the fact that the RS cannot receive and transmit simultaneously on the same channel resource. In SDD relaying, this loss in spectral efficiency is circumvented by giving up the strict separation of downlink and uplink signals by either time division duplex or frequency division duplex. Two novel concepts for the derivation of the linear beamforming filters at the RS are proposed; they can be designed either by a three-step or a one-step concept. In SDD relaying, receive signals at S1 are interfered by transmit signals of S1, and receive signals at S2 are interfered by transmit signals of S2. An efficient method in order to combat this kind of interference is proposed in this paper. Furthermore, it is shown how the overall spectral efficiency of SDD relaying can be improved if the channels from S1 and S2 to the RS have different qualities.

  14. Performance Analysis of RF-FSO Multi-Hop Networks

    KAUST Repository

    Makki, Behrooz

    2017-05-12

    We study the performance of multi-hop networks composed of millimeter wave (MMW)-based radio frequency (RF) and free-space optical (FSO) links. The results are obtained in the cases with and without hybrid automatic repeat request (HARQ). Taking the MMW characteristics of the RF links into account, we derive closed-form expressions for the network outage probability. We also evaluate the effect of various parameters such as power amplifiers efficiency, number of antennas as well as different coherence times of the RF and the FSO links on the system performance. Finally, we present mappings between the performance of RF- FSO multi-hop networks and the ones using only the RF- or the FSO-based communication, in the sense that with appropriate parameter settings the same outage probability is achieved in these setups. The results show the efficiency of the RF-FSO setups in different conditions. Moreover, the HARQ can effectively improve the outage probability/energy efficiency, and compensate the effect of hardware impairments in RF-FSO networks. For common parameter settings of the RF-FSO dual- hop networks, outage probability 10^{-4} and code rate 3 nats-per-channel-use, the implementation of HARQ with a maximum of 2 and 3 retransmissions reduces the required power, compared to the cases with no HARQ, by 13 and 17 dB, respectively.

  15. Estrogens and congeners from spent hops (Humulus lupulus).

    Science.gov (United States)

    Chadwick, Lucas R; Nikolic, Dejan; Burdette, Joanna E; Overk, Cassia R; Bolton, Judy L; van Breemen, Richard B; Fröhlich, Roland; Fong, Harry H S; Farnsworth, Norman R; Pauli, Guido F

    2004-12-01

    Estrogenicity-directed fractionation of a methanol extract of the strobiles of Humulus lupulus that had been extracted previously with supercritical CO(2), known as "spent hops", led to the isolation and identification of 22 compounds including 12 prenylated chalcones (1-8, 10-13), five prenylflavanones (14-17), 4-hydroxybenzaldehyde (18), sitosterol-3-O-beta-glucopyranoside (19), humulinone (20), and cohumulinone (21). In addition, the prenylated chalcone xanthohumol C (9a) was obtained as a 6:1 mixture along with its 1' ',2' '-dihydro derivative (9b). Three new chalcones (4, 11, 12) and four previously unreported constituents of hops (5, 6, 9b, 13) are reported. The structures of the new compounds were determined through a combination of spectrometric techniques including 1D and 2D NMR, HRESIMS, and ESIMS-MS. Full 1H NMR spin system analyses were performed to characterize the higher-order glucopyranosyl, prenyl, and chalcone B-ring spectra of the isolates. The principle estrogen 8-prenylnaringenin (15) from hops is an artifact formed along with its positional isomer 6-prenylnaringenin (16) through the spontaneous isomerization of the pro-estrogenic chalcone DMX (7).

  16. Critical appraisal of the fewest switches algorithm for surface hopping

    Science.gov (United States)

    Granucci, Giovanni; Persico, Maurizio

    2007-04-01

    In this paper the authors address the problem of internal consistency in trajectory surface hopping methods, i.e., the requirement that the fraction of trajectories running on each electronic state equals the probabilities computed by the electronic time-dependent Schrödinger equation, after averaging over all trajectories. They derive a formula for the hopping probability in Tully's "fewest switches" spirit that would yield a rigorously consistent treatment. They show the relationship of Tully's widely used surface hopping algorithm with the "exact" prescription that cannot be applied when running each trajectory independently. They also bring out the connection of the consistency problem with the coherent propagation of the electronic wave function and the artifacts caused by coherent Rabi-type oscillations of the state probabilities in weak coupling regimes. A real molecule (azobenzene) and two ad hoc models serve as examples to illustrate the above theoretical arguments. Following a proposal by Truhlar's group [Zhu et al., J. Chem. Phys. 121, 7658 (2004) Zhu et al., J. Chem. Theory Comput. 1, 527 (2005)], they apply a decoherence correction to the state probabilities, in conjunction with Tully's algorithm, and they obtain satisfactory results in terms of internal consistency and of agreement with the outcomes of quantum wave packet calculations.

  17. Numerical calculation of impurity charge state distributions

    Energy Technology Data Exchange (ETDEWEB)

    Crume, E. C.; Arnurius, D. E.

    1977-09-01

    The numerical calculation of impurity charge state distributions using the computer program IMPDYN is discussed. The time-dependent corona atomic physics model used in the calculations is reviewed, and general and specific treatments of electron impact ionization and recombination are referenced. The complete program and two examples relating to tokamak plasmas are given on a microfiche so that a user may verify that his version of the program is working properly. In the discussion of the examples, the corona steady-state approximation is shown to have significant defects when the plasma environment, particularly the electron temperature, is changing rapidly.

  18. Some aspects of impurity trapping of muons

    CERN Document Server

    Karlsson, E

    1981-01-01

    Several aspects of muon trapping in metals have been studied during the last two years, but the situation is still far from clear. The precise nature of the traps as well as the mechanisms leading to trapping seem to require more detailed investigations than those carried out so far. This review contains therefore a certain number of ideas which should be regarded as working hypotheses rather than established facts or descriptions of positive muon behaviour. The author considers muons in FCC metals (Al:Mn and Cu), and impurity trapping in BCC metals (V, Nb, Ta, Fe). (21 refs).

  19. Germanium Blocked Impurity Band (BIB) detectors

    Science.gov (United States)

    Haller, E. E.; Baumann, H.; Beeman, J. W.; Hansen, W. L.; Luke, P. N.; Lutz, M.; Rossington, C. S.; Wu, I. C.

    1989-01-01

    Information is given in viewgraph form. The advantages of the Si blocked impurity band (BIB) detector invented by M. D. Petroff and M. G. Stabelbroek are noted: smaller detection volume leading to a reduction of cosmic ray interference, extended wavelength response because of dopant wavefunction overlap, and photoconductive gain of unity. It is argued that the stated advantages of Si BIB detectors should be realizable for Ge BIB detectors. Information is given on detector development, subtrate choice and preparation, wafer polising, epitaxy, characterization of epi layers, and preliminary Ge BIB detector test results.

  20. Electric Effect of Impurity in Square Quantum Wires

    Institute of Scientific and Technical Information of China (English)

    LI Kui-Hua; ZHANG Ying-Tao; LI You-Cheng

    2004-01-01

    @@ In the presence of an electric fidd perpendicular to the axes of the wire, the binding energy of shallow donor impurity in finite square quantum well wires is calculated. For different impurity positions and aspect ratios of the wires, we investigate the Stark shift of the 1s-like state energy of the impurity by expanding the wavefunction into a two-dimensional Fourier series and by using the variational scheme.

  1. Recommended methods for purification of solvents and tests for impurities

    CERN Document Server

    Coetzee, J F

    1982-01-01

    Recommended Methods for Purification of Solvents and Tests for Impurities is a compilation of recommended procedures for purification of solvents and tests for solvent impurities. Ten solvents are covered: acetonitrile, sulfolane, propylene carbonate, dimethyl sulfoxide, dimethylformamide, hexamethylphosphoramide, pyridine, ethylenediamine, N-methylacetamide, and N-methylpropionamide. This book is comprised of 12 chapters and opens with an introduction to general aspects of impurity effects. The rationale for the selection of solvent is explained, and the relative reactivities of solutes in di

  2. Interactions of Ultracold Impurity Particles with Bose-Einstein Condensates

    Science.gov (United States)

    2015-06-23

    AFRL-OSR-VA-TR-2015-0141 INTERACTIONS OF ULTRACOLD IMPURITY PARTICLES WITH BOSE- EINSTEIN CONDENSATES Georg Raithel UNIVERSITY OF MICHIGAN Final...SUBTITLE Interactions of ultracold impurity particles with Bose- Einstein Condensates 5a. CONTRACT NUMBER FA9550-10-1-0453 5b. GRANT NUMBER 5c...Interactions of ultracold impurity particles with Bose- Einstein Condensates Contract/Grant #: FA9550-10-1-0453 Reporting Period: 8/15/2010 to 2/14

  3. Renormalization-group calculation of excitation properties for impurity models

    Science.gov (United States)

    Yoshida, M.; Whitaker, M. A.; Oliveira, L. N.

    1990-05-01

    The renormalization-group method developed by Wilson to calculate thermodynamical properties of dilute magnetic alloys is generalized to allow the calculation of dynamical properties of many-body impurity Hamiltonians. As a simple illustration, the impurity spectral density for the resonant-level model (i.e., the U=0 Anderson model) is computed. As a second illustration, for the same model, the longitudinal relaxation rate for a nuclear spin coupled to the impurity is calculated as a function of temperature.

  4. Anomalous screening of quantum impurities by a neutral environment

    OpenAIRE

    Yakaboylu, Enderalp; Lemeshko, Mikhail

    2016-01-01

    It is a common knowledge that an effective interaction of a quantum impurity with an electromagnetic field can be screened by surrounding charge carriers, whether mobile or static. Here we demonstrate that very strong, `anomalous' screening can take place in the presence of a neutral, weakly-polarizable environment, due to an exchange of orbital angular momentum between the impurity and the bath. Furthermore, we show that it is possible to generalize all phenomena related to isolated impuriti...

  5. Dilution Effects on Two-Dimensional Heisenberg Antiferromagnets with Non-Magnetic Spin-Gapped Ground State

    OpenAIRE

    Yasuda, Chitoshi; Todo, Synge; Matsumoto, Munehisa; Takayama, Hajime

    2002-01-01

    Dilution effects on spin-1/2 quantum Heisenberg antiferromagnets with a non-magnetic spin-gapped ground state are studied by means of the qunatum Monte Carlo simulation. In the site-diluted system, an antiferromagnetic long-range order (AF-LRO) is induced at an infinitesimal concentration of dilution due to an effective coupling $\\tilde{J}_{mn}$ between induced magnetic moments. In the bond-diluted case, on the other hand, the AF-LRO is not induced up to a certain concentration of dilution du...

  6. Enhancement of thermal spin transfer torque by double-barrier magnetic tunnel junctions with a nonmagnetic metal spacer

    Science.gov (United States)

    Chen, C. H.; Tseng, P.; Yang, Y. Y.; Hsueh, W. J.

    2017-01-01

    Enhancement of thermal spin transfer torque in a double-barrier magnetic tunnel junction with a nonmagnetic-metal spacer is proposed in this study. The results indicate that, given the same temperature difference, thermal spin transfer torque and charge current density for the proposed double barrier magnetic tunnel junction configuration can be approximately twice as much as that of the traditional single-barrier magnetic tunnel junctions. This enhancement can be attributed to the resonant tunneling mechanism in the double-barrier structure.

  7. Influence of Non-Magnetic Substitutional Atoms on Spontaneous Moment and Curie Temperature of Ce2Co17 Compounds

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The structure and magnetic properties of Ce2Co17-xMx(M=Ga,Al and Si) compounds for M concentrations up to x=5 were studied by means of X-ray diffraction and magnetic measurements. The experimental results show that the Curie temperatures and Co spontaneous magnetization decrease significantly with increasing the addition of non-magnetic substitutional atoms, and that Si which has a minimum solid solubility in Ce2Co17 causes a largest reduction of Curie temperature, spontaneous magnetization and moment per Co atom compared with Ga and Al.

  8. Fractal growth in impurity-controlled solidification in lipid monolayers

    DEFF Research Database (Denmark)

    Fogedby, Hans C.; Sørensen, Erik Schwartz; Mouritsen, Ole G.

    1987-01-01

    A simple two-dimensional microscopic model is proposed to describe solidifcation processes in systems with impurities which are miscible only in the fluid phase. Computer simulation of the model shows that the resulting solids are fractal over a wide range of impurity concentrations and impurity...... diffusional constants. A fractal-forming mechanism is suggested for impurity-controlled solidification which is consistent with recent experimental observations of fractal growth of solid phospholipid domains in monolayers. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  9. Influence of impurities on the specific optical rotation of cefozopran.

    Science.gov (United States)

    Liu, Shu-Yu; Li, Ya-Ping; Hu, Chang-Qin

    2012-07-01

    The impurities of cefozopran hydrochloride are analyzed using high-performance liquid chromatography (HPLC) with UV absorbance and optical rotation (OR) detection. The results show that the impurities can affect the specific optical rotation of the cefozopran product. Due to the different composition of impurities, the Chinese cefozopran hydrochloride product has a specific optical rotation different from the Japanese product. The relationship between impurity limits and specific optical rotation of cefozopran hydrochloride is revealed. The results provide a scientific rationale for setting the limit of specific optical rotation of cefozopran hydrochloride.

  10. Observation of interactions between impurities and hydrodynamics solitons

    Institute of Scientific and Technical Information of China (English)

    L(U) Lei; CHEN Weizhong; ZHU Yifei; LIN Han

    2004-01-01

    We have experimentally investigated interactions between impurities and hydrodynamic solitons in a shallow water trough subject to vertical vibration. The impurities are minor convex and concave defects located on the bottom of the trough, slightly varying the water depth. The experiments show that a shallow impurity will attract breathers and kinks while a deep one will repel them. These observations are consistent with the theoretical prediction proposed in the continuous Frankel-Kontorova model with impurities and can also be explained in the view of energy absorption.

  11. Ground- and excited-state impurity bands in quantum wells

    Science.gov (United States)

    Ghazali, A.; Gold, A.; Serre, J.

    1989-02-01

    The density of states and the spectral density of electrons in quantum wells with charged impurities are calculated with use of a multiple-scattering method. The impurity-density-dependent broadening and the gradual merging of the ground (1s) and excited (2p+/-,2s) impurity levels into impurity bands are investigated. At low density the shapes of the 1s, 2p+/-, and 2s spectral densities are found to be in excellent agreement with the analytical results obtained for the ideal two-dimensional Coulomb problem.

  12. A Hop-by-Hop Congestion-Aware Routing Protocol for Heterogeneous Mobile Ad-hoc Networks

    CERN Document Server

    Narasimhan, B

    2009-01-01

    In Heterogeneous mobile ad hoc networks (MANETs) congestion occurs with limited resources. Due to the shared wireless channel and dynamic topology, packet transmissions suffer from interference and fading. In heterogeneous ad hoc networks, throughput via a given route is depending on the minimum data rate of all its links. In a route of links with various data rates, if a high data rate node forwards more traffic to a low data rate node, there is a chance of congestion, which leads to long queuing delays in such routes. Since hop count is used as a routing metric in traditional routing, it do not adapt well to mobile nodes. A congestion-aware routing metric for MANETs should incorporate transmission capability, reliability, and congestion around a link. In this paper, we propose to develop a hop-by-hop congestion aware routing protocol which employs a combined weight value as a routing metric, based on the data rate, queuing delay, link quality and MAC overhead. Among the discovered routes, the route with min...

  13. Influence of zigzag edges on the Ruderman-Kittel-Kasuya-Yosida interaction between magnetic impurities in graphene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Akbari-Sharbaf, A., E-mail: aakbaris@uwo.ca; Cottam, M. G., E-mail: cottam@uwo.ca [Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

    2014-11-21

    Localized magnetic impurity centres in graphene can interact through the π-electrons, leading to an effective Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. A RKKY-type study is presented for graphene ribbons with zigzag edges. Specifically investigations of how the edges modify the interaction between two localized magnetic moments are made by using a tight-binding Hamiltonian to describe the hopping of the π-electrons between adjacent sites and a contact term for interactions with the localized moments. In terms of a Green's function formalism for the excitation spectrum, which comprises modified bulk modes and two different types of localized edge modes, explicit analytical expressions are obtained for the RKKY interaction for any two magnetic sites on the graphene ribbon. The results enable us to determine the RKKY contributions that arise individually from the bulk-like modes and from the two types of edge modes in the zigzag geometry. The importance of these contributions varies depending on the proximity of the magnetic impurities to each other and to an edge.

  14. Droppin’ Knowledge on Race: Hip-Hop, White Adolescents, and Anti-Racism Education

    Directory of Open Access Journals (Sweden)

    Steven Netcoh

    2013-10-01

    Full Text Available In this essay, the author examines how Hip-Hop can be mobilized in anti-racism educational initatives.  The author claims that existing research on Hip-Hop and white adolescents suggests a negative corrleation between white youths' engagement with Hip-Hop and their understanding of how race and racism function in American society.  In response to this research, the author argues Hip-Hop's diverse racial discourses and ideologies must be made the subject of direct and critical inquiry in secondary and post-secondary classrooms to maximize its democratic potential.  The author outlines specific approaches for how teachers can employ Hip-Hop in anti-racism curricula in secondary and post-secondary classrooms.  Collectively, the essay serves as a preliminary investigation of Hip-Hop pedagogies of race and whiteness.

  15. «Hip hop culture»: a review of its potential as an educational tool

    Directory of Open Access Journals (Sweden)

    Alberto RODRÍGUEZ ÁLVAREZ

    2014-12-01

    Full Text Available  This paper reviews the meaning of «hip hop culture» as a contemporary musical phenomenon, and how rap is a feature of the social and educational activities aimed at youth. The purpose of it is to show the evolution of hip hop, its agents, its practices, and its relationship with the world of the music industry and cultural action.It provides useful information on the contents of the Spanish rap lyrics that have been analyzed to check the messages transmitted, the ideas and references to the precepts legitimized in «hip hop culture». This is an approach to the idea that hip hop is a means of expression of social concerns and values that identify the hip hop culture. So, this study aims to provide a better knowledge of some educational experiences that have used hip hop as a tool to promote change in neighbourhoods, social groups or youth groups.

  16. Deterministic Multi-hop Controlled Teleportation of Arbitrary Single-Qubit State

    Science.gov (United States)

    Peng, Jia-yin; Bai, Ming-qiang; Mo, Zhi-wen

    2017-10-01

    Multi-hop teleportation is of great significance due to long-distance delivery of quantum information and wireless quantum communication networks. In existing protocols of multi-hop teleportation, the more nodes, the smaller the success probability. In this paper, fusing the ideas of multi-hop teleportation and controlled teleportation, we put forward a scheme for implementing multi-hop controlled teleportation of single-qubit state. A set of ingenious three-qubit non-maximally entangled states are constructed to serve as the quantum channels. The information is perfectly transmitted hop by hop through teleportation under the control of the supervisors. Unit success probability can be achieved independent of channel's entanglement degree and the number of intermediate nodes. Only Pauli operations, single-qubit rotation, Hadamard gate, controlled-NOT gate, Bell-state measurement and single-qubit measurement are used in our scheme, so this scheme is easily realized in physical experiment.

  17. Blind Compressed Sensing Parameter Estimation of Non-cooperative Frequency Hopping Signal

    Directory of Open Access Journals (Sweden)

    Chen Ying

    2016-10-01

    Full Text Available To overcome the disadvantages of a non-cooperative frequency hopping communication system, such as a high sampling rate and inadequate prior information, parameter estimation based on Blind Compressed Sensing (BCS is proposed. The signal is precisely reconstructed by the alternating iteration of sparse coding and basis updating, and the hopping frequencies are directly estimated based on the results. Compared with conventional compressive sensing, blind compressed sensing does not require prior information of the frequency hopping signals; hence, it offers an effective solution to the inadequate prior information problem. In the proposed method, the signal is first modeled and then reconstructed by Orthonormal Block Diagonal Blind Compressed Sensing (OBD-BCS, and the hopping frequencies and hop period are finally estimated. The simulation results suggest that the proposed method can reconstruct and estimate the parameters of noncooperative frequency hopping signals with a low signal-to-noise ratio.

  18. INFLUENCE OF THE NONMAGNETIC METAL SPACER ON THE MAGNETIC PROPERTIES AND MICROSTRUCTURE OF THE MULTILAYER FILMS

    Institute of Scientific and Technical Information of China (English)

    M.H. Li; G.H. Yu; F.W. Zhu; H.W. Jiang; W.Y. Lai

    2006-01-01

    Ta/NiFe/Bi (Ag,Cu)/FeMn/Ta and Ta/NiFeⅠ/FeMn/Bi (Ag, Cu)/NiFeⅡ/Ta films were prepared by magnetic sputtering. The texture and the dependences of the exchange-coupling field on the thickness of Bi, Ag, and Cu in Ta/NiFe/Bi(Ag, Cu) /FeMn/Ta and Ta/NiFeⅠ/FeMn/Bi(Ag, Cu)/NiFeⅡ/Ta films were studied. XPS results indicate that the Bi atoms migrated into the FeMn layer during the deposition process and a FeMnBi alloy was probably formed or the Bi atoms existed as an impurity in the FeMn layer in Ta/NiFe/Bi(Ag, Cu)/FeMn/Ta. Otherwise, in Ta/NiFeⅠ/FeMn/Bi (Ag, Cu ) /NiFeⅡ/Ta films, Bi, Ag, and Cu atoms do not remain entirely at the interface of the FeMn/NiFeⅡ film, but at least partly segregate to the surface of the NiFe film.

  19. An Improved DY-Hop Localization Algorithm with Reduced Node Location Error for Wireless Sensor Networks

    Science.gov (United States)

    Chen, Hongyang; Sezaki, Kaoru; Deng, Ping; So, Hing Cheung

    In this paper, we propose a new localization algorithm and improve the DV-Hop algorithm by using a differential error correction scheme that is designed to reduce the location error accumulated over multiple hops. This scheme needs no additional hardware support and can be implemented in a distributed way. The proposed method can improve location accuracy without increasing communication traffic and computing complexity. Simulation results show the performance of the proposed algorithm is superior to that of the DV-Hop algorithm.

  20. New Class of Optimal Frequency-Hopping Sequences by Polynomial Residue Class Rings

    CERN Document Server

    Ma, Wenping

    2010-01-01

    In this paper, using the theory of polynomial residue class rings, a new construction is proposed for frequency hopping patterns having optimal Hamming autocorrelation with respect to the well-known $Lempel$-$Greenberger$ bound. Based on the proposed construction, many new $Peng$-$Fan$ optimal families of frequency hopping sequences are obtained. The parameters of these sets of frequency hopping sequences are new and flexible.

  1. Path-integral Monte Carlo simulations for electronic dynamics on molecular chains. II. Transport across impurities

    Science.gov (United States)

    Mühlbacher, Lothar; Ankerhold, Joachim

    2005-05-01

    Electron transfer (ET) across molecular chains including an impurity is studied based on a recently improved real-time path-integral Monte Carlo (PIMC) approach [L. Mühlbacher, J. Ankerhold, and C. Escher, J. Chem. Phys. 121 12696 (2004)]. The reduced electronic dynamics is studied for various bridge lengths and defect site energies. By determining intersite hopping rates from PIMC simulations up to moderate times, the relaxation process in the extreme long-time limit is captured within a sequential transfer model. The total transfer rate is extracted and shown to be enhanced for certain defect site energies. Superexchange turns out to be relevant for extreme gap energies only and then gives rise to different dynamical signatures for high- and low-lying defects. Further, it is revealed that the entire bridge compound approaches a steady state on a much shorter time scale than that related to the total transfer. This allows for a simplified description of ET along donor-bridge-acceptor systems in the long-time range.

  2. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    Science.gov (United States)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For

  3. Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy₂Ti₂O₇.

    Science.gov (United States)

    Anand, V K; Tennant, D A; Lake, B

    2015-11-01

    Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility χ(ac)(T), dc magnetic susceptibility χ(T), isothermal magnetization M(H) and heat capacity C(p)(T) measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent χ(ac)(T) data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca(2+) substitution for magnetic Dy(3+) is similar to the previous study on nonmagnetic isovalent Y(3+) substituted Dy(2-x)Y(x) Ti2O7 (for low levels of dilution), however the suppression of spin-freezing behavior is substantially stronger for Ca than Y. The Cole-Cole plot analysis reveals semicircular character and a single relaxation mode in Dy1.8Ca0.2Ti2O7 as for Dy2Ti2O7. No noticeable change in the insulating behavior of Dy2Ti2O7 results from the holes produced by 10% Ca(2+) substitution for Dy(3+) ions.

  4. Component masses of young, wide, non-magnetic white dwarf binaries in the Sloan Digital Sky Survey Data Release 7

    Science.gov (United States)

    Baxter, R. B.; Dobbie, P. D.; Parker, Q. A.; Casewell, S. L.; Lodieu, N.; Burleigh, M. R.; Lawrie, K. A.; Külebi, B.; Koester, D.; Holland, B. R.

    2014-06-01

    We present a spectroscopic component analysis of 18 candidate young, wide, non-magnetic, double-degenerate binaries identified from a search of the Sloan Digital Sky Survey Data Release 7 (DR7). All but two pairings are likely to be physical systems. We show SDSS J084952.47+471247.7 + SDSS J084952.87+471249.4 to be a wide DA + DB binary, only the second identified to date. Combining our measurements for the components of 16 new binaries with results for three similar, previously known systems within the DR7, we have constructed a mass distribution for the largest sample to date (38) of white dwarfs in young, wide, non-magnetic, double-degenerate pairings. This is broadly similar in form to that of the isolated field population with a substantial peak around M ˜ 0.6 M⊙. We identify an excess of ultramassive white dwarfs and attribute this to the primordial separation distribution of their progenitor systems peaking at relatively larger values and the greater expansion of their binary orbits during the final stages of stellar evolution. We exploit this mass distribution to probe the origins of unusual types of degenerates, confirming a mild preference for the progenitor systems of high-field-magnetic white dwarfs, at least within these binaries, to be associated with early-type stars. Additionally, we consider the 19 systems in the context of the stellar initial mass-final mass relation. None appear to be strongly discordant with current understanding of this relationship.

  5. Optimization of conditions for supercritical fluid extraction of flavonoids from hops (Humulus lupulus L.)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Waste hops are good sources offlavonoids. Extraction offlavonoids from waste hops (SC-CO2 extracted hops) using supercritical fluids technology was investigated. Various temperatures, pressures and concentrations of ethanol (modifier) and the ratio (w/w) of solvent to material were tested in this study. The results of single factor and orthogonal experiments showed that at 50℃, 25 MPa, the ratio of solvent to material (50%), ethanol concentration (80%) resulted in maximum extraction yield flavonoids (7.8 mg/g). HPLC-MS analysis of the extracts indicated that flavonoids obtained were xanthohumol, the principal prenylflavonoid in hops.

  6. Antifeedant activity of xanthohumol and supercritical carbon dioxide extract of spent hops against stored product pests.

    Science.gov (United States)

    Jackowski, J; Hurej, M; Rój, E; Popłoński, J; Kośny, L; Huszcza, E

    2015-08-01

    Xanthohumol, a prenylated flavonoid from hops, and a supercritical carbon dioxide extract of spent hops were studied for their antifeedant activity against stored product insect pests: Sitophilus granarius L., Tribolium confusum Duv. and Trogoderma granarium Everts. Xanthohumol exhibited medium deterrent activity against the adults of S. granarius L. and larvae of T. confusum Duv. The spent hops extract was more active than xanthohumol towards the adults of T. confusum Duv. The potential application of the crude spent hops extract as a feeding deterrent against the stored product pests is proposed.

  7. Hip-hop as a resource for understanding the urban context

    Science.gov (United States)

    Brown, Bryan

    2010-06-01

    This review explores Edmin's "Science education for the hip-hop generation" by documenting how he frames hip-hop as a means to access urban student culture. He argues that hip-hop is more than a mere music genre, but rather a culture that provides young people with ways of connecting to the world. Two primary ideas emerged as central to his work. First, he contends that students develop communal relationships and collective identities based on the common experiences expressed in hip-hop. Second, he identifies how the conscious recognition of institutional oppression serves a central feature in urban schools. Emdin's rich, and personal call for a greater understanding of hip-hop culture provides the text with an unmatched strength. He skillfully uses personal narratives from his own experience as well as quotes and references from hip-hop songs to make the nuances of hip hop transparent to science educators. Conversely, the limitation of this text is found in its unfulfilled promise to provide pragmatic examples of how to engage in a hip-hop based science education. Emdin's work is ultimately valuable as it extends our current knowledge about urban students and hip-hop in meaningful ways.

  8. Hops in Virginia: Need-to-Know Information about the Industry

    OpenAIRE

    Siegle, Laura

    2016-01-01

    Provides information and background concerning the growing of hops in Virginia, including production, management, new grower considerations, harvest, marketing, and the development of the industry in the state.

  9. Hop (Humulus lupulus)-derived bitter acids as multipotent bioactive compounds.

    Science.gov (United States)

    Van Cleemput, Marjan; Cattoor, Ko; De Bosscher, Karolien; Haegeman, Guy; De Keukeleire, Denis; Heyerick, Arne

    2009-06-01

    Hop acids, a family of bitter compounds derived from the hop plant (Humulus lupulus), have been reported to exert a wide range of effects, both in vitro and in vivo. They exhibit potential anticancer activity by inhibiting cell proliferation and angiogenesis, by inducing apoptosis, and by increasing the expression of cytochrome P450 detoxification enzymes. Furthermore, hop bitter acids are effective against inflammatory and metabolic disorders, which makes them challenging candidates for the treatment of diabetes mellitus, cardiovascular diseases, and metabolic syndrome. This review summarizes the current knowledge on hop bitter acids, including both phytochemical aspects, as well as the biological and pharmacological properties of these compounds.

  10. Generalized adiabatic polaron hopping: Meyer-Neldel compensation and Poole-Frenkel behavior.

    Science.gov (United States)

    Emin, David

    2008-04-25

    The commonly employed adiabatic treatment of polaron hopping is extended to treat the continuous alteration of a carrier wave function with the atoms' movements and a carrier's long-range interaction with a polar surrounding. These features, respectively, introduce carrier-induced softening of the atoms' vibrations and a hopping activation energy that depends on hopping distance. The Meyer-Neldel compensation effect results from carrier-induced softening of vibrations. Poole-Frenkel behavior emerges for electric-field driven polaron hopping in ionic and polar media.

  11. 3-Sulfanyl-4-methylpentan-1-ol in Dry-Hopped Beers: First Evidence of Glutathione S-Conjugates in Hop (Humulus lupulus L.).

    Science.gov (United States)

    Kankolongo Cibaka, Marie-Lucie; Decourrière, Laura; Lorenzo-Alonso, Celso-José; Bodart, Etienne; Robiette, Raphaël; Collin, Sonia

    2016-11-16

    Monovarietal dry-hopped beers were produced with the dual-purpose hop cultivars Amarillo, Hallertau Blanc, and Mosaic. The grapefruit-like 3-sulfanyl-4-methylpentan-1-ol was found in all three beers at concentrations much higher than expected on the basis of the free thiol content in hop. Even cysteinylated precursors proved unable to explain our results. As observed in wine, the occurrence of S-glutathione precursors was therefore suspected in hop. The analytical standards of S-3-(4-methyl-1-hydroxypentyl)glutathione, never described before, and of S-3-(1-hydroxyhexyl)glutathione, previously evidenced in grapes, were chemically synthesized. An optimized extraction of glutathionylated precursors was then applied to Amarillo, Hallertau Blanc, and Mosaic hop samples. HPLC-ESI(+)MS/MS revealed, for the first time, the occurrence of S-3-(1-hydroxyhexyl)glutathione and S-3-(4-methyl-1-hydroxypentyl)glutathione in hop, at levels well above those reported for their cysteinylated counterparts. S-3-(1-Hydroxyhexyl)glutathione emerged in all cases as the major adduct in hop. Yet, although 3-sulfanylhexan-1-ol seems relatively ubiquitous in free, cysteinylated, and glutathionylated forms, the glutathione adduct of 3-sulfanyl-4-methylpentan-1-ol, never evidenced in other plants up to now, was found only in the Hallertau Blanc variety.

  12. Glycolic acid physical properties and impurities assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pickenheim, B. R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bibler, N. E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hay, M. S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-06-08

    This document has been revised due to recent information that the glycolic acid used in Savannah River National Laboratory (SRNL) experiments contains both formaldehyde and methoxyacetic acid. These impurities were in the glycolic acid used in the testing included in this report and in subsequent testing using DuPont (now called Chemours) supplied Technical Grade 70 wt% glycolic acid. However, these impurities were not reported in earlier revisions. Additional data concerning the properties of glycolic acid have also been added to this report. The Defense Waste Processing Facility (DWPF) is planning to implement a nitric-glycolic acid flowsheets to increase attainment to meet closure commitment dates during Sludge Batch 9. In fiscal year 2009, SRNL was requested to determine the physical properties of formic and glycolic acid blends. Blends of formic acid in glycolic acid were prepared and their physical properties tested. Increasing amounts of glycolic acid led to increases in blend density, viscosity and surface tension as compared to the 90 wt% formic acid that is currently used at DWPF. These increases are small, however, and are not expected to present any difficulties in terms of processing. The effect of sulfur impurities in Technical Grade glycolic acid was studied for its impact on DWPF glass quality. While the glycolic acid specification allows for more sulfate than the current formic acid specification, the ultimate impact is expected to be on the order of 0.033 wt% sulfur in glass. Note that lower sulfur content glycolic acid could likely be procured at some increased cost if deemed necessary. A paper study on the effects of radiation on glycolic acid was performed. The analysis indicates that substitution of glycolic acid for formic acid would not increase the radiolytic production rate of H2 and cause an adverse effect in the Slurry Receipt and Adjustment Tank (SRAT) or Slurry Mix Evaporator (SME) process. It has been cited that glycolic acid

  13. Effects of bulk charged impurities on the bulk and surface transport in three-dimensional topological insulators

    Science.gov (United States)

    Skinner, B.; Chen, T.; Shklovskii, B. I.

    2013-09-01

    In the three-dimensional topological insulator (TI), the physics of doped semiconductors exists literally side-by-side with the physics of ultrarelativistic Dirac fermions. This unusual pairing creates a novel playground for studying the interplay between disorder and electronic transport. In this mini-review, we focus on the disorder caused by the three-dimensionally distributed charged impurities that are ubiquitous in TIs, and we outline the effects it has on both the bulk and surface transport in TIs. We present self-consistent theories for Coulomb screening both in the bulk and at the surface, discuss the magnitude of the disorder potential in each case, and present results for the conductivity. In the bulk, where the band gap leads to thermally activated transport, we show how disorder leads to a smaller-than-expected activation energy that gives way to variable-range hopping at low temperatures. We confirm this enhanced conductivity with numerical simulations that also allow us to explore different degrees of impurity compensation. For the surface, where the TI has gapless Dirac modes, we present a theory of disorder and screening of deep impurities, and we calculate the corresponding zero-temperature conductivity. We also comment on the growth of the disorder potential in passing from the surface of the TI into the bulk. Finally, we discuss how the presence of a gap at the Dirac point, introduced by some source of time-reversal symmetry breaking, affects the disorder potential at the surface and the mid-gap density of states.

  14. Impurity Conductivity in Semiconductors Resulting from Radiant Excitation

    OpenAIRE

    TOULANOV, Vakhab T.; DAVLETOVA, Aziza SH.

    2001-01-01

    This paper deals with the derivation of common formulae for induced impurity photosensibility with an arbitrary set of energy levels in the semiconductor gap. We give the expression for the real recombinational situation with two types of impurity levels as well. The basic properties and certain common peculiarities concerning induced photoconductivity in semiconductors are under consideration.

  15. Steady-state organization of binary mixtures by active impurities

    DEFF Research Database (Denmark)

    Sabra, Mads Christian; Gilhøj, Henriette; Mouritsen, Ole G.

    1998-01-01

    The structural reorganization of a phase-separated binary mixture in the presence of an annealed dilution of active impurities is studied by computer-simulation techniques via a simple two-dimensional lattice-gas model. The impurities, each of which has two internal states with different affinity...

  16. Multiple magnetic impurities on surfaces: Scattering and quasiparticle interference

    NARCIS (Netherlands)

    Mitchell, A.

    2015-01-01

    We study systems of multiple interacting quantum impurities deposited on a metallic surface in a three-dimensional host. For the real-space two-impurity problem, using numerical renormalization group calculations, a rich range of behavior is shown to arise due to the interplay between Kondo physics

  17. Tight-Binding Description of Impurity States in Semiconductors

    Science.gov (United States)

    Dominguez-Adame, F.

    2012-01-01

    Introductory textbooks in solid state physics usually present the hydrogenic impurity model to calculate the energy of carriers bound to donors or acceptors in semiconductors. This model treats the pure semiconductor as a homogeneous medium and the impurity is represented as a fixed point charge. This approach is only valid for shallow impurities…

  18. Fluid and gyrokinetic simulations of impurity transport at JET

    DEFF Research Database (Denmark)

    Nordman, H; Skyman, A; Strand, P

    2011-01-01

    Impurity transport coefficients due to ion-temperature-gradient (ITG) mode and trapped-electron mode turbulence are calculated using profile data from dedicated impurity injection experiments at JET. Results obtained with a multi-fluid model are compared with quasi-linear and nonlinear gyrokineti...

  19. Effects of impurities on growth habit of KDP crystal

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of metaphosphate, boric acid and quaternary ammonium cations with different concentration on the growth habit of KDP crystal are reported. The results are analyzed and discussed, which show that the effects of different impurities on the growth habit of KDP are not the same. It is due to the different adsorption mechanism of the impurities.

  20. The Mg impurity in nitride alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zvanut, M. E.; Willoughby, W. R.; Sunay, U. R. [Department of Physics, University of Alabama at Birmingham, Birmingham AL (United States); Koleske, D. D.; Allerman, A. A. [Sandia National Laboratory, Albuquerque NM (United States); Wang, Ke; Araki, Tsutomu [Department of Photonics, Ritsumeikan University, Kusatsu, Shiga (Japan); Nanishi, Yasushi [Department of Photonics, Ritsumeikan University, Kusatsu, Shiga, Japan and WCU Program, Department of Materials Science and Engineering, Seoul National University, Seoul (Korea, Republic of)

    2014-02-21

    Although several magnetic resonance studies address the Mg acceptor in GaN, there are few reports on Mg doping in the alloys, where hole production depends strongly on the Al or In content. Our electron paramagnetic resonance (EPR) measurements of the p-type alloys suggest that the Mg impurity retains the axial symmetry, characteristic of a p-type dopant in both alloys; however, In and Al produce additional, different characteristics of the acceptor. In InGaN, the behavior is consistent with a lowering of the acceptor level and increasing hole density as In concentration increases. For AlGaN, the amount of neutral Mg decreases with increasing Al content, which is attributed to different kinetics of hydrogen diffusion thought to occur in samples with higher Al mole fraction.

  1. Light-absorbing impurities in Arctic snow

    Directory of Open Access Journals (Sweden)

    S. J. Doherty

    2010-08-01

    Full Text Available Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983–1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 2005–2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland ice sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study.

    The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC, the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow: Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, Subarctic Canada 14, Svalbard 13, Northern Norway 21, Western Arctic Russia 26, Northeastern Siberia 17. Concentrations are more variable in the European Arctic than in Arctic Canada or the Arctic Ocean, probably because of the proximity

  2. Gaussian impurity moving through a Bose-Einstein superfluid

    Science.gov (United States)

    Pinsker, Florian

    2017-09-01

    In this paper a finite Gaussian impurity moving through an equilibrium Bose-Einstein condensate at T = 0 is studied. The problem can be described by a Gross-Pitaevskii equation, which is solved perturbatively. The analysis is done for systems of 2 and 3 spatial dimensions. The Bogoliubov equation solutions for the condensate perturbed by a finite impurity are calculated in the co-moving frame. From these solutions the total energy of the perturbed system is determined as a function of the width and the amplitude of the moving Gaussian impurity and its velocity. In addition we derive the drag force the finite sized impurity approximately experiences as it moves through the superfluid, which proves the existence of a superfluid phase for finite extensions of the impurities below the speed of sound. Finally we find that the force increases with velocity until an inflection point from which it decreases again in 2 and 3d.

  3. Reduction of Oxygen Impurity in Multicrystalline Silicon Production

    Directory of Open Access Journals (Sweden)

    Bing Gao

    2013-01-01

    Full Text Available Effective control of oxygen impurity in multicrystalline silicon is required for the production of a high-quality crystal. The basic principle and some techniques for reducing oxygen impurity in multicrystalline silicon during the unidirectional solidification process are described in this paper. The oxygen impurity in multicrystalline silicon mainly originates from the silica crucible. To effectively reduce the oxygen impurity, it is essential to reduce the oxygen generation and enhance oxygen evaporation. For reduction of oxygen generation, it is necessary to prevent or weaken any chemical reaction with the crucible, and for the enhancement of oxygen evaporation, it is necessary to control convection direction of the melt and strengthen gas flow above the melt. Global numerical simulation, which includes heat transfer in global furnace, argon gas convection inside furnace, and impurity transport in both melt and gas regions, has been implemented to validate the above methods.

  4. Spectroscopic Analysis of Impurity Precipitates in CdS Films

    Energy Technology Data Exchange (ETDEWEB)

    Webb, J. D.; Keane, J.; Ribelin, R.; Gedvilas, L.; Swartzlander, A.; Ramanathan, K.; Albin, D. S.; Noufi, R.

    1999-10-31

    Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Devices incorporating chemical-bath-deposited (CBD) CdS are comparable in quality to devices incorporating purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this paper, we summarize and review the results of Fourier transform infrared (FTIR), Auger, electron microprobe, and X-ray photoelectron spectroscopic (XPS) analyses of the impurities in CBD CdS films. We show that these impurities differ as a function of substrate type and film deposition conditions. We also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

  5. Impurity transport in trapped electron mode driven turbulence

    CERN Document Server

    Mollén, A; Moradi, S; Fülöp, T

    2013-01-01

    Collisionless trapped electron mode turbulence is studied by gyrokinetic simulations with the GYRO code. Its impact on radial transport of high-Z trace impurities close to the core is thoroughly investigated, including the situation when a poloidally varying equilibrium electrostatic potential is present, and the dependence of the zero-flux impurity density gradient (peaking factor) on local plasma parameters is presented. Parameters such as ion-to-electron temperature ratio, electron temperature gradient and main species density gradient mainly affect the impurity peaking through their impact on mode characteristics. The poloidal asymmetry, the safety factor and magnetic shear have the strongest effect on impurity peaking, and it is shown that under certain scenarios where trapped electron modes are dominant, core accumulation of high-Z impurities can be avoided.

  6. [Impurity removal technology of Tongan injection in liquid preparation process].

    Science.gov (United States)

    Yang, Xu-fang; Wang, Xiu-hai; Bai, Wei-rong; Kang, Xiao-dong; Liu, Jun-chao; Wu, Yun; Xiao, Wei

    2015-08-01

    In order to effectively remove the invalid impurities in Tongan injection, optimize the optimal parameters of the impurity removal technology of liquid mixing process, in this paper, taking Tongan injection as the research object, with the contents of celandine alkali, and sinomenine, solids reduction efficiency, and related substances inspection as the evaluation indexes, the removal of impurities and related substances by the combined process of refrigeration, coction and activated carbon adsorption were investigated, the feasibility of the impurity removal method was definited and the process parameters were optimized. The optimized process parameters were as follows: refrigerated for 36 h, boiled for 15 min, activated carbon dosage of 0.3%, temperature 100 degrees C, adsorption time 10 min. It can effectively remove the tannin, and other impurities, thus ensure the quality and safety of products.

  7. Quantum dynamics of impurities coupled to a Fermi sea

    Science.gov (United States)

    Parish, Meera M.; Levinsen, Jesper

    2016-11-01

    We consider the dynamics of an impurity atom immersed in an ideal Fermi gas at zero temperature. We focus on the coherent quantum evolution of the impurity following a quench to strong impurity-fermion interactions, where the interactions are assumed to be short range like in cold-atom experiments. To approximately model the many-body time evolution, we use a truncated basis method, where at most two particle-hole excitations of the Fermi sea are included. When the system is initially noninteracting, we show that our method exactly captures the short-time dynamics following the quench, and we find that the overlap between initial and final states displays a universal nonanalytic dependence on time in this limit. We further demonstrate how our method can be used to compute the impurity spectral function, as well as describe many-body phenomena involving coupled impurity spin states, such as Rabi oscillations in a medium or highly engineered quantum quenches.

  8. Interplay of quantum impurities and topological surface modes

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Shi-Han; Deng, Ming-Xun; Qiu, Jian-Ming; Zhong, Qing-Hu; Yang, Mou; Wang, Rui-Qiang, E-mail: rqwanggzu@163.com

    2015-11-06

    The interplay of an Anderson quantum impurity with topological surface modes is studied. We find that the quantum impurity scattering can locally destroy the Dirac electron spectra by creating a significant resonance exactly at the Dirac point, in stark contrast to the case of classic impurities. When an external magnetic field is applied to the topological insulator (TI) surfaces, a bound state is found either at the gap edges or within the gap. We discuss the coexistence of the Kondo resonance and the bound state and their effect on TI local density of states. - Highlights: • A resonance at the Dirac point is found, differing from classic impurity theory. • A magnetic field-induced bound state is found within the energy gap. • Impurity Kondo resonance can cause corresponding signatures in the LDOS of TIs. • The results can be tuned by a gate voltage or a chemical potential.

  9. Micellar liquid chromatography of terephthalic acid impurities.

    Science.gov (United States)

    Richardson, Ashley E; McPherson, Shakeela D; Fasciano, Jennifer M; Pauls, Richard E; Danielson, Neil D

    2017-03-31

    The production of terephthalic acid (TPA) by oxidation of p-xylene is an important industrial process because high purity TPA is required for the synthesis of polyethylene terephthalate, the primary polymer used to make plastic beverage bottles. Few separation methods have been published that aim to separate TPA from eight major aromatic acid impurities. This work describes a "green" micellar liquid chromatography (MLC) method using a C18 column (100×2.1mm, 3.5μm), an acidic 1% sodium dodecyl sulfate (SDS) mobile phase, and a simple step flow rate gradient to separate TPA and eight impurities in less than 20min. The resulting chromatogram shows excellent peak shape and baseline resolution of all nine acids, in which there are two sets of isomers. Partition coefficients and equilibrium constants have been calculated for the two sets of isomers by plotting the reciprocal of the retention factor versus micelle concentration. Quantitation of the nine analytes in an actual industrial TPA sample is possible. Limits of detection for all nine acids range from 0.180 to 1.53ppm (2.16-19.3 pmoles) and limits of quantitation range from 0.549 to 3.45ppm (6.48-43.0 pmoles). In addition, the method was tested on two other reversed phase C18 columns of similar dimensions and particle diameter from different companies. Neither column showed quite the same peak resolution as the original column, however slight modifications to the mobile phase could improve the separation. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Insulator-to-metal transition in vanadium supersaturated silicon: variable-range hopping and Kondo effect signatures

    Science.gov (United States)

    García-Hemme, E.; Montero, D.; García-Hernansanz, R.; Olea, J.; Mártil, I.; González-Díaz, G.

    2016-07-01

    We report the observation of the insulator-to-metal transition in crystalline silicon samples supersaturated with vanadium. Ion implantation followed by pulsed laser melting and rapid resolidification produce high quality single-crystalline silicon samples with vanadium concentrations that exceed equilibrium values in more than 5 orders of magnitude. Temperature-dependent analysis of the conductivity and Hall mobility values for temperatures from 10 K to 300 K indicate that a transition from an insulating to a metallic phase is obtained at a vanadium concentration between 1.1  ×  1020 and 1.3  ×  1021 cm-3. Samples in the insulating phase present a variable-range hopping transport mechanism with a Coulomb gap at the Fermi energy level. Electron wavefunction localization length increases from 61 to 82 nm as the vanadium concentration increases in the films, supporting the theory of impurity band merging from delocalization of levels states. On the metallic phase, electronic transport present a dispersion mechanism related with the Kondo effect, suggesting the presence of local magnetic moments in the vanadium supersaturated silicon material.

  11. Path-integral Monte Carlo simulations for electronic dynamics on molecular chains. I. Sequential hopping and super exchange

    Science.gov (United States)

    Mühlbacher, Lothar; Ankerhold, Joachim; Escher, Charlotte

    2004-12-01

    An improved real-time quantum Monte Carlo procedure is presented and applied to describe the electronic transfer dynamics along molecular chains. The model consists of discrete electronic sites coupled to a thermal environment which is integrated out exactly within the path integral formulation. The approach is numerically exact and its results reduce to known analytical findings (Marcus theory, golden rule) in proper limits. Special attention is paid to the role of superexchange and sequential hopping at lower temperatures in symmetric donor-bridge-acceptor systems. In contrast to previous approximate studies, superexchange turns out to play a significant role only for extremely high-lying bridges where the transfer is basically frozen or for extremely low temperatures where for weaker dissipation a description in terms of rate constants is no longer feasible. For bridges with increasing length an algebraic decrease of the yield is found for short as well as for long bridges. The approach can be extended to electronic systems with more complicated topologies including impurities and in presence of external time-dependent forces.

  12. Hopping in a supercooled binary Lennard-Jones liquid

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Dyre, Jeppe

    1998-01-01

    A binary Lennard–Jones liquid has been investigated by molecular dynamics at equilibrium supercooled conditions. At the lowest temperature investigated, hopping is present in the system as indicated by a secondary peak in 4r2Gs(r,t), where Gs(r,t) is the van Hove self correlation function....... To examine the dynamics of the system, we consider transitions between the inherent structures (local minima in the potential energy) along the trajectory. We conclude that the plateau in the mean square displacement found at lower temperatures is indeed a result of particles being trapped in local "cages...

  13. Lejos de NYC: El hip-hop en Chile

    OpenAIRE

    Rainer Quitzow

    2005-01-01

    En este artículo se abordan las manifestaciones concretas de una forma cultural urbana exportada desde Occidente a los países en desarrollo. A través de una reconstrucción de la historia de la cultura hip hop en Chile, se han intendado esbozar algunas conclusiones sobre su influencia en la formación de una identidad cultural urbana, tratando además de relacionar el desarrollo histórico del movimiento y de las prácticas actuales de la juventud en Santiago con tendencias más amplias en la socie...

  14. Novel Frequency Hopping Sequences Generator Based on AES Algorithm

    Institute of Scientific and Technical Information of China (English)

    李振荣; 庄奕琪; 张博; 张超

    2010-01-01

    A novel frequency hopping(FH) sequences generator based on advanced encryption standard(AES) iterated block cipher is proposed for FH communication systems.The analysis shows that the FH sequences based on AES algorithm have good performance in uniformity, correlation, complexity and security.A high-speed, low-power and low-cost ASIC of FH sequences generator is implemented by optimizing the structure of S-Box and MixColumns of AES algorithm, proposing a hierarchical power management strategy, and applying ...

  15. Totally asymmetric exclusion processes with spatially periodic hopping rates

    Science.gov (United States)

    Lakatos, Greg; Kolomeisky, Anatoly; Chou, Tom

    2004-03-01

    Using mean-field and numerical methods, we analyze the steady-state behavior of totally asymmetric simple exclusion processes (TASEPs) containing periodically varying movement rates. In our models particles at a majority sites hop to the right with rate p_1, while particles occupying a periodically arranged set of sites move to the right at rate p_2. While exact solutions for the steady-state particle currents and densities are not found, the mean field results show good agreement with data derived from extensive Monte-Carlo simulations.

  16. Conscious Hip-Hop, Change, and the Obama Era

    Directory of Open Access Journals (Sweden)

    Murray Forman

    2010-05-01

    Full Text Available This article identifies a particular aspect of hip-hop’s range of cultural production—conscious rap—in order to isolate one of the more politicized discursive options available to youth in America and a site where critical perspectives on post-Civil Rights America have emerged most forcefully. It further suggests that Obama’s political rise corresponds with a new phase in hip-hop and has impacted the ways in which its creative artists frame and articulate issues of race, class, and identity.

  17. Semiclassical quantization of nonadiabatic systems with hopping periodic orbits

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Mikiya, E-mail: mikiya.fujii@gmail.com; Yamashita, Koichi [Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); JST, CREST, Tokyo 113-8656 (Japan)

    2015-02-21

    We present a semiclassical quantization condition, i.e., quantum–classical correspondence, for steady states of nonadiabatic systems consisting of fast and slow degrees of freedom (DOFs) by extending Gutzwiller’s trace formula to a nonadiabatic form. The quantum–classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow DOF, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels. In addition to the semiclassical quantization condition, we also discuss chaotic dynamics involved in the classical limit of nonadiabatic dynamics.

  18. Semiclassical quantization of nonadiabatic systems with hopping periodic orbits

    Science.gov (United States)

    Fujii, Mikiya; Yamashita, Koichi

    2015-02-01

    We present a semiclassical quantization condition, i.e., quantum-classical correspondence, for steady states of nonadiabatic systems consisting of fast and slow degrees of freedom (DOFs) by extending Gutzwiller's trace formula to a nonadiabatic form. The quantum-classical correspondence indicates that a set of primitive hopping periodic orbits, which are invariant under time evolution in the phase space of the slow DOF, should be quantized. The semiclassical quantization is then applied to a simple nonadiabatic model and accurately reproduces exact quantum energy levels. In addition to the semiclassical quantization condition, we also discuss chaotic dynamics involved in the classical limit of nonadiabatic dynamics.

  19. Lejos de NYC: El hip-hop en Chile

    OpenAIRE

    Rainer Quitzow

    2005-01-01

    En este artículo se abordan las manifestaciones concretas de una forma cultural urbana exportada desde Occidente a los países en desarrollo. A través de una reconstrucción de la historia de la cultura hip hop en Chile, se han intendado esbozar algunas conclusiones sobre su influencia en la formación de una identidad cultural urbana, tratando además de relacionar el desarrollo histórico del movimiento y de las prácticas actuales de la juventud en Santiago con tendencias más amplias en la socie...

  20. Olhares figurados, figuras do olhar: fotografia e movimento Hip Hop

    OpenAIRE

    Rodrigues, Juliana de Oliveira

    2006-01-01

    O presente estudo toma por objeto as fotografias realizadas por integrantes do Movimento Hip Hop, da cidade de São Carlos (SP), nas quais constroem um olhar sobre si mesmo pelas experiências da vida em grupo. Centrada nos procedimentos de figurativização e tematização, esta pesquisa preocupa-se com as diversas figuras enredadas pelo conjunto fotográfico, que implicam em estratégias discursivas capazes de tornar visível os diferentes modos de o grupo se mostrar no mundo. Em decorrência disso, ...

  1. High-Speed On-Board Data Processing for Science Instruments: HOPS

    Science.gov (United States)

    Beyon, Jeffrey

    2015-01-01

    The project called High-Speed On-Board Data Processing for Science Instruments (HOPS) has been funded by NASA Earth Science Technology Office (ESTO) Advanced Information Systems Technology (AIST) program during April, 2012 â€" April, 2015. HOPS is an enabler for science missions with extremely high data processing rates. In this three-year effort of HOPS, Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) and 3-D Winds were of interest in particular. As for ASCENDS, HOPS replaces time domain data processing with frequency domain processing while making the real-time on-board data processing possible. As for 3-D Winds, HOPS offers real-time high-resolution wind profiling with 4,096-point fast Fourier transform (FFT). HOPS is adaptable with quick turn-around time. Since HOPS offers reusable user-friendly computational elements, its FPGA IP Core can be modified for a shorter development period if the algorithm changes. The FPGA and memory bandwidth of HOPS is 20 GB/sec while the typical maximum processor-to-SDRAM bandwidth of the commercial radiation tolerant high-end processors is about 130-150 MB/sec. The inter-board communication bandwidth of HOPS is 4 GB/sec while the effective processor-to-cPCI bandwidth of commercial radiation tolerant high-end boards is about 50-75 MB/sec. Also, HOPS offers VHDL cores for the easy and efficient implementation of ASCENDS and 3-D Winds, and other similar algorithms. A general overview of the 3-year development of HOPS is the goal of this presentation.

  2. Influence of a dispersion of magnetic and nonmagnetic nanoparticles on the magnetic Fredericksz transition of the liquid crystal 5CB

    Science.gov (United States)

    Mouhli, Ahmed; Ayeb, Habib; Othman, Tahar; Fresnais, Jérôme; Dupuis, Vincent; Nemitz, Ian R.; Pendery, Joel S.; Rosenblatt, Charles; Sandre, Olivier; Lacaze, Emmanuelle

    2017-07-01

    A long time ago, Brochard and de Gennes predicted the possibility of significantly decreasing the critical magnetic field of the Fredericksz transition (the magnetic Fredericksz threshold) in a mixture of nematic liquid crystals and ferromagnetic particles, the so-called ferronematics. This phenomenon is rarely measured to be large, due to soft homeotropic anchoring induced at the nanoparticle surface. Here we present an optical study of the magnetic Fredericksz transition combined with a light scattering study of the classical nematic liquid crystal: the pentylcyanobiphenyl (5CB), doped with 6 nm diameter magnetic and nonmagnetic nanoparticles. Surprisingly, for both nanoparticles, we observe at room temperature a net decrease of the threshold field of the Fredericksz transition at low nanoparticle concentrations, which appears associated with a coating of the nanoparticles by a brush of polydimethylsiloxane copolymer chains inducing planar anchoring of the director on the nanoparticle surface. Moreover, the magnetic Fredericksz threshold exhibits nonmonotonic behavior as a function of the nanoparticle concentration for both types of nanoparticles, first decreasing down to a value from 23% to 31% below that of pure 5CB, then increasing with a further increase of nanoparticle concentration. This is interpreted as an aggregation starting at around 0.02 weight fraction that consumes more isolated nanoparticles than those introduced when the concentration is increased above c =0.05 weight fraction (volume fraction 3.5 ×10-2 ). This shows the larger effect of isolated nanoparticles on the threshold with respect to aggregates. From dynamic light scattering measurements we deduced that, if the decrease of the magnetic threshold when the nanoparticle concentration increases is similar for both kinds of nanoparticles, the origin of this decrease is different for magnetic and nonmagnetic nanoparticles. For nonmagnetic nanoparticles, the behavior may be associated with a

  3. Lejos de NYC: El hip-hop en Chile

    Directory of Open Access Journals (Sweden)

    Rainer Quitzow

    2005-03-01

    Full Text Available En este artículo se abordan las manifestaciones concretas de una forma cultural urbana exportada desde Occidente a los países en desarrollo. A través de una reconstrucción de la historia de la cultura hip hop en Chile, se han intendado esbozar algunas conclusiones sobre su influencia en la formación de una identidad cultural urbana, tratando además de relacionar el desarrollo histórico del movimiento y de las prácticas actuales de la juventud en Santiago con tendencias más amplias en la sociedad chilena. En particular, se ha intentado determinar si el hip hop proporciona un formato significativo para la expresión de los problemas de los jóvenes urbanos de Chile, o si es parte de lo que algunos autores denominan una “pérdida cultural”, como consecuencia del capitalismo global y el imperialismo cultural de Estados Unidos.

  4. HOPS 383: AN OUTBURSTING CLASS 0 PROTOSTAR IN ORION

    Energy Technology Data Exchange (ETDEWEB)

    Safron, Emily J.; Megeath, S. Thomas; Booker, Joseph [Ritter Astrophysical Observatory, Department of Physics and Astronomy, University of Toledo, Toledo, OH (United States); Fischer, William J. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Furlan, Elise; Rebull, Luisa M. [Infrared Processing and Analysis Center, Caltech, Pasadena, CA (United States); Stutz, Amelia M. [Max-Planck-Institut für Astronomie, Heidelberg (Germany); Stanke, Thomas [European Southern Observatory, Garching bei München (Germany); Billot, Nicolas [Instituto de Radio Astronomía Milimétrica, Granada (Spain); Tobin, John J. [Leiden Observatory, Leiden (Netherlands); Ali, Babar [Space Science Institute, Boulder, CO (United States); Allen, Lori E. [National Optical Astronomy Observatory, Tucson, AZ (United States); Watson, Dan M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Wilson, T. L., E-mail: wjfischer@gmail.com [Naval Research Laboratory, Washington, DC (United States)

    2015-02-10

    We report the dramatic mid-infrared brightening between 2004 and 2006 of Herschel Orion Protostar Survey (HOPS) 383, a deeply embedded protostar adjacent to NGC 1977 in Orion. By 2008, the source became a factor of 35 brighter at 24 μm with a brightness increase also apparent at 4.5 μm. The outburst is also detected in the submillimeter by comparing APEX/SABOCA to SCUBA data, and a scattered-light nebula appeared in NEWFIRM K{sub s} imaging. The post-outburst spectral energy distribution indicates a Class 0 source with a dense envelope and a luminosity between 6 and 14 L{sub ⊙}. Post-outburst time-series mid- and far-infrared photometry show no long-term fading and variability at the 18% level between 2009 and 2012. HOPS 383 is the first outbursting Class 0 object discovered, pointing to the importance of episodic accretion at early stages in the star formation process. Its dramatic rise and lack of fading over a 6 year period hint that it may be similar to FU Ori outbursts, although the luminosity appears to be significantly smaller than the canonical luminosities of such objects.

  5. Hops for Menopausal Vasomotor Symptoms: Mechanisms of Action

    Science.gov (United States)

    Abdi, Fatemeh; Mobedi, Hamid

    2016-01-01

    Menopause is a critical stage of women's life associated with various complaints and distresses. Vasomotor symptoms (VMS), such as hot flushes, night sweats, sleep disturbances, and fatigue, are the most common menopause symptoms affecting about 50% to 80% of middle-aged women. Obviously, these symptoms, resulting from estrogen deficiency during menopause, can exert negative effects on women's health and quality of life and thus require to be managed through approaches such as hormone replacement therapy (HRT). Many herbal treatments for menopause symptoms contain and its components such as 8-prenylnaringenin, 6-PN, isoxanthohumol and xanthohumol. Recent in-vivo studies have highlighted the ability of 8-prenylnaringenin to reduce serum-luteinizing hormone (LH) and follicle-stimulating hormone (FSH), to increase serum prolactin levels and uterine weight, and to induce vaginal hyperplastic epithelium. Previous research has shown that hops extract can strongly bind to both estrogen receptors, stimulate alkaline phosphatase activity in Ishikawa cells, and upregulate presenelin-2 and progesterone receptor mRNA in Ishikawa cells. Numerous clinical trials have documented significant reductions in the frequency of hot flushes following the administration of hop-containing preparations. Nevertheless, further clinical trials with larger sample size and longer follow-up are warranted to confirm such benefits. PMID:27617238

  6. Thermopower of molecular junctions: Tunneling to hopping crossover in DNA

    Science.gov (United States)

    Korol, Roman; Kilgour, Michael; Segal, Dvira

    2016-12-01

    We study the electrical conductance G and the thermopower S of single-molecule junctions and reveal signatures of different transport mechanisms: off-resonant tunneling, on-resonant coherent (ballistic) motion, and multi-step hopping. These mechanisms are identified by studying the behavior of G and S while varying molecular length and temperature. Based on a simple one-dimensional model for molecular junctions, we derive approximate expressions for the thermopower in these different regimes. Analytical results are compared to numerical simulations, performed using a variant of Büttiker's probe technique, the so-called voltage-temperature probe, which allows us to phenomenologically introduce environmentally induced elastic and inelastic electron scattering effects, while applying both voltage and temperature biases across the junction. We further simulate the thermopower of GC-rich DNA sequences with mediating A:T blocks and manifest the tunneling-to-hopping crossover in both the electrical conductance and the thermopower, in accord with measurements by Li et al. [Nat. Commun. 7, 11294 (2016)].

  7. Communication: Global flux surface hopping in Liouville space

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Linjun, E-mail: linjun.wang@usc.edu, E-mail: prezhdo@usc.edu; Prezhdo, Oleg V., E-mail: linjun.wang@usc.edu, E-mail: prezhdo@usc.edu [Department of Chemistry, University of Southern California, Los Angeles, California 90089-1062 (United States); Sifain, Andrew E. [Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0485 (United States)

    2015-11-21

    Recent years have witnessed substantial progress in the surface hopping (SH) formulation of non-adiabatic molecular dynamics. A generalization of the traditional fewest switches SH (FSSH), global flux SH (GFSH) utilizes the gross population flow between states to derive SH probabilities. The Liouville space formulation of FSSH puts state populations and coherences on equal footing, by shifting the hopping dynamics from Hilbert to Liouville space. Both ideas have shown superior results relative to the standard FSSH in Hilbert space, which has been the most popular approach over the past two and a half decades. By merging the two ideas, we develop GFSH in Liouville space. The new method is nearly as straightforward as the standard FSSH, and carries comparable computational expense. Tested with a representative super-exchange model, it gives the best performance among all existing techniques in the FSSH series. The obtained numerical results match almost perfectly the exact quantum mechanical solutions. Moreover, the results are nearly invariant under the choice of a basis state representation for SH, in contrast to the earlier techniques which exhibit notable basis set dependence. Unique to the developed approach, this property is particularly encouraging, because exact quantum dynamics is representation independent. GFSH in Liouville space significantly improves accuracy and applicability of SH for a broad range of chemical and physical processes.

  8. CPG Control for Biped Hopping Robot in Unpredictable Environment

    Institute of Scientific and Technical Information of China (English)

    Tingting Wang; Wei Guo; Mantian Li; Fusheng Zha; Lining Sun

    2012-01-01

    A CPG control mechanism is proposed for hopping motion control of biped robot in unpredictable environment.Based on analysis of robot motion and biological observation of animal's control mechanism,the motion control task is divided into two simple parts:motion sequence control and output force control.Inspired by a two-level CPG model,a two-level CPG control mechanism is constructed to coordinate the drivers of robot joint,while various feedback information are introduced into the control mechanism.Interneurons within the control mechanism are modeled to generate motion rhythm and pattern promptly for motion sequence control; motoneurons are modeled to control output forces of joint drivers in real time according to feedbacks.The control system can perceive changes caused by unknown perturbations and environment changes according to feedback information,and adapt to unpredictable environment by adjusting outputs of neurons.The control mechanism is applied to a biped hopping robot in unpredictable environment on simulation platform,and stable adaptive motions are obtained.

  9. Hopping electron model with geometrical frustration: kinetic Monte Carlo simulations

    Science.gov (United States)

    Terao, Takamichi

    2016-09-01

    The hopping electron model on the Kagome lattice was investigated by kinetic Monte Carlo simulations, and the non-equilibrium nature of the system was studied. We have numerically confirmed that aging phenomena are present in the autocorrelation function C ({t,tW )} of the electron system on the Kagome lattice, which is a geometrically frustrated lattice without any disorder. The waiting-time distributions p(τ ) of hopping electrons of the system on Kagome lattice has been also studied. It is confirmed that the profile of p (τ ) obtained at lower temperatures obeys the power-law behavior, which is a characteristic feature of continuous time random walk of electrons. These features were also compared with the characteristics of the Coulomb glass model, used as a model of disordered thin films and doped semiconductors. This work represents an advance in the understanding of the dynamics of geometrically frustrated systems and will serve as a basis for further studies of these physical systems.

  10. A decentralized scheduling algorithm for time synchronized channel hopping

    Directory of Open Access Journals (Sweden)

    Andrew Tinka

    2011-09-01

    Full Text Available Time Synchronized Channel Hopping (TSCH is an existing Medium Access Control scheme which enables robust communication through channel hopping and high data rates through synchronization. It is based on a time-slotted architecture, and its correct functioning depends on a schedule which is typically computed by a central node. This paper presents, to our knowledge, the first scheduling algorithm for TSCH networks which both is distributed and which copes with mobile nodes. Two variations on scheduling algorithms are presented. Aloha-based scheduling allocates one channel for broadcasting advertisements for new neighbors. Reservation- based scheduling augments Aloha-based scheduling with a dedicated timeslot for targeted advertisements based on gossip information. A mobile ad hoc motorized sensor network with frequent connectivity changes is studied, and the performance of the two proposed algorithms is assessed. This performance analysis uses both simulation results and the results of a field deployment of floating wireless sensors in an estuarial canal environment. Reservation-based scheduling performs significantly better than Aloha-based scheduling, suggesting that the improved network reactivity is worth the increased algorithmic complexity and resource consumption.

  11. Effective Capacity of Two-Hop Wireless Communication Systems

    CERN Document Server

    Qiao, Deli; Velipasalar, Senem

    2011-01-01

    A two-hop wireless communication link in which a source sends data to a destination with the aid of an intermediate relay node is studied. It is assumed that there is no direct link between the source and the destination, and the relay forwards the information to the destination by employing the decode-and-forward scheme. Both the source and intermediate relay nodes are assumed to operate under statistical quality of service (QoS) constraints imposed as limitations on the buffer overflow probabilities. The maximum constant arrival rates that can be supported by this two-hop link in the presence of QoS constraints are characterized by determining the effective capacity of such links as a function of the QoS parameters and signal-to-noise ratios at the source and relay, and the fading distributions of the links. The analysis is performed for both full-duplex and half-duplex relaying. Through this study, the impact upon the throughput of having buffer constraints at the source and intermediate relay nodes is ide...

  12. Spin-Dependent Hopping Transport in Magnetic Perovskites

    Science.gov (United States)

    Bruynseraede, Y.; Wagner, P.; Gordon, I.; Trappeniers, L.; Herlach, F.; Moshchalkov, V.

    1998-03-01

    Epitaxial films of Nd_0.5Sr_0.5MnO3 show a transition from paramagnetic-semiconducting to ferromagnetic-quasimetallic behavior at TC = 207 K and a colossal negative magnetoresistivity (CMR) of 750 % at 150 K, 12 T. Hall effect studies indicate a slightly increasing carrier density at the para- to ferromagnetic transition from 0.3 to 0.5 holes per unit cell. External magnetic fields do not affect these densities and the CMR effect is therefore caused by a field-induced enhancement of carrier mobility. The mobility gain can be described by a Mott-type model in which the hopping barrier is extended by a term related to the mutual spin orientation at neighbouring hopping sites, i. e. Mn ions of different valency. This model predicts a scaling behaviour of the CMR effect at constant temperature proportional to the Brillouin function \\cal B in the ferromagnetic state, and to \\cal B^2 for the paramagnet. Both results are confirmed by CMR measurements in pulsed magnetic fields up to 50 T.

  13. Contributions to the quality control of two crops of economic importance : hops and yerba mate

    NARCIS (Netherlands)

    Wilson, Erica Georgina

    2012-01-01

    Quality control of plants is essential and at the same time very challenging.In this thesis, studies involving quality issues of two plants used in the production of two popular beverages, hops (in beer) and Ilex paraguariensis (yerba mate) were undertaken. Hops are used as bittering agents and to

  14. Characterisation of the Plasmodium falciparum Hsp70-Hsp90 organising protein (PfHop).

    Science.gov (United States)

    Gitau, Grace W; Mandal, Pradipta; Blatch, Gregory L; Przyborski, Jude; Shonhai, Addmore

    2012-03-01

    Malaria is caused by Plasmodium species, whose transmission to vertebrate hosts is facilitated by mosquito vectors. The transition from the cold blooded mosquito vector to the host represents physiological stress to the parasite, and additionally malaria blood stage infection is characterised by intense fever periods. In recent years, it has become clear that heat shock proteins play an essential role during the parasite's life cycle. Plasmodium falciparum expresses two prominent heat shock proteins: heat shock protein 70 (PfHsp70) and heat shock protein 90 (PfHsp90). Both of these proteins have been implicated in the development and pathogenesis of malaria. In eukaryotes, Hsp70 and Hsp90 proteins are functionally linked by an essential adaptor protein known as the Hsp70-Hsp90 organising protein (Hop). In this study, recombinant P. falciparum Hop (PfHop) was heterologously produced in E. coli and purified by nickel affinity chromatography. Using specific anti-PfHop antisera, the expression and localisation of PfHop in P. falciparum was investigated. PfHop was shown to co-localise with PfHsp70 and PfHsp90 in parasites at the trophozoite stage. Gel filtration and co-immunoprecipitation experiments suggested that PfHop was present in a complex together with PfHsp70 and PfHsp90. The association of PfHop with both PfHsp70 and PfHsp90 suggests that this protein may mediate the functional interaction between the two chaperones.

  15. Contributions to the quality control of two crops of economic importance : hops and yerba mate

    NARCIS (Netherlands)

    Wilson, Erica Georgina

    2012-01-01

    Quality control of plants is essential and at the same time very challenging.In this thesis, studies involving quality issues of two plants used in the production of two popular beverages, hops (in beer) and Ilex paraguariensis (yerba mate) were undertaken. Hops are used as bittering agents and to

  16. Topological phase transitions driven by next-nearest-neighbor hopping in two-dimensional lattices

    NARCIS (Netherlands)

    Beugeling, W.; Everts, J.C.; de Morais Smith, C.

    2012-01-01

    For two-dimensional lattices in a tight-binding description, the intrinsic spin-orbit coupling, acting as a complex next-nearest-neighbor hopping, opens gaps that exhibit the quantum spin Hall effect. In this paper, we study the effect of a real next-nearest-neighbor hopping term on the band structu

  17. Polish Hip Hop as a Form of Multiliteracies and Situated Learning

    Science.gov (United States)

    Torrence, Michael L.

    2009-01-01

    The purpose of this ethnographic study was to examine Hip Hop in Poland through the lens of multiliteracies and situated learning. This analysis is concerned with the transmission of Hip Hop to and within Wroclaw, Poland, and its acculturation and assimilation in Wroclaw, Poland. Further, this study seeks to illustrate how professional Polish Hip…

  18. Hip-Hop and a Hybrid Text in a Postsecondary English Class

    Science.gov (United States)

    Sanchez, Deborah M.

    2010-01-01

    This study explores the epistemology present in hip-hop music and its reflection in the writing of one African American student in a postsecondary transitional English class. An integration of hip-hop and academic literacy practices in the student's essay challenges the supremacy of a "standard" academic English and deficit perspectives about…

  19. Evaluating the Impact of Transmission Power on Selecting Tall Vehicles as Best Next Communication Hop

    NARCIS (Netherlands)

    Qiao, Yu; Klein Wolterink, Wouter; Karagiannis, Georgios; Heijenk, Geert

    2012-01-01

    The relatively low height of antennas on communicating vehicles in Vehicular Ad Hoc Networks (VANETs) makes one hop and as well multi-hop Vehicle-to-Vehicle (V2V) communication susceptible to obstruction by other vehicles on the road. When the transmitter or receiver (or both) is a Tall vehi- cle, (

  20. Connectivity model for Inter-working multi-hop wireless networks

    CSIR Research Space (South Africa)

    Salami, O

    2009-08-01

    Full Text Available pairs in inter-working multi-hop wireless networks can be evaluated based on the availability of radio links and communication routes. This paper presents an analytical study of the link and route availability in inter-working multi-hop wireless networks....

  1. Sampling Practices and Social Spaces: Exploring a Hip-Hop Approach to Higher Education

    Science.gov (United States)

    Petchauer, Emery

    2010-01-01

    Much more than a musical genre, hip-hop culture exists as an animating force in the lives of many young adults. This article looks beyond the moral concerns often associated with rap music to explore how hip-hop as a larger set of expressions and practices implicates the educational experiences, activities, and approaches for students. The article…

  2. Affiliation and Alienation: Hip-Hop, Rap, and Urban Science Education

    Science.gov (United States)

    Emdin, Christopher

    2010-01-01

    The critiques of rap artists and other participants in hip-hop culture provide data for teachers and researchers to investigate the attitudes of US urban youth towards schooling. This study explores the complex relationships between hip-hop and science education by examining how rap lyrics project beliefs about schooling, the relevance of existing…

  3. Trends in German Hip Hop Music and Its Usefulness for the Classroom

    Science.gov (United States)

    Schmidt, Johannes

    2008-01-01

    German hip hop music has proved productive, especially since 2000 when rap in Germany experienced something like a first crisis. As a response, German hip hop artists and record labels have ventured off in several different directions including other musical genres, different topics, and new approaches to German rap. This article discusses the…

  4. Empowerment in Context: Lessons from Hip-Hop Culture for Social Work Practice

    Science.gov (United States)

    Travis, Raphael, Jr.; Deepak, Anne

    2011-01-01

    Hip-hop culture can be used as a conduit to enhanced cultural competence and practice skills through the individual and community empowerment framework. This framework is introduced as a tool for direct practice that allows social workers to understand the competing messages within hip-hop culture and how they may impact youths by promoting or…

  5. Student Perceptions of the Hip Hop Culture's Influence on the Undergraduate Experience

    Science.gov (United States)

    Wessel, Roger D.; Wallaert, Kerry A.

    2011-01-01

    This study sought to determine how identification and engagement with the hip hop culture influenced the educational experiences of undergraduate students at a Midwestern, predominately White university by interviewing 11 students who self-identified as being immersed in the hip hop culture. Through a qualitative, phenomenological investigation,…

  6. Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping.

    Science.gov (United States)

    Bobbert, Maarten F; Richard Casius, L J

    2011-05-27

    The purpose of this study was to understand how humans regulate their 'leg stiffness' in hopping, and to determine whether this regulation is intended to minimize energy expenditure. 'Leg stiffness' is the slope of the relationship between ground reaction force and displacement of the centre of mass (CM). Variations in leg stiffness were achieved in six subjects by having them hop at maximum and submaximum heights at a frequency of 1.7 Hz. Kinematics, ground reaction forces and electromyograms were measured. Leg stiffness decreased with hopping height, from 350 N m(-1) kg(-1) at 26 cm to 150 N m(-1) kg(-1) at 14 cm. Subjects reduced hopping height primarily by reducing the amplitude of muscle activation. Experimental results were reproduced with a model of the musculoskeletal system comprising four body segments and nine Hill-type muscles, with muscle stimulation STIM(t) as only input. Correspondence between simulated hops and experimental hops was poor when STIM(t) was optimized to minimize mechanical energy expenditure, but good when an objective function was used that penalized jerk of CM motion, suggesting that hopping subjects are not minimizing energy expenditure. Instead, we speculated, subjects are using a simple control strategy that results in smooth movements and a decrease in leg stiffness with hopping height.

  7. New STS molecular markers for assessment of genetic diversity and DNA fingerprinting in hop (Humulus lupulus L.)

    National Research Council Canada - National Science Library

    Vrba, Lukas; Matousek, Jaroslav; Patzak, Josef

    2007-01-01

    .... We demonstrate the usefulness of these STS markers and compare them to SSRs for identifying hop genotypes and estimating genetic diversity in a collection of 68 hop cultivars from around the world...

  8. Recent trends in the impurity profile of pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Kavita Pilaniya

    2010-01-01

    Full Text Available Various regulatory authorities such as the International Conference on Harmonization (ICH, the United States Food and Drug administration (FDA, and the Canadian Drug and Health Agency (CDHA are emphasizing on the purity requirements and the identification of impurities in Active Pharmaceutical Ingredients (APIs. The various sources of impurity in pharmaceutical products are - reagents, heavy metals, ligands, catalysts, other materials like filter aids, charcoal, and the like, degraded end products obtained during \\ after manufacturing of bulk drugs from hydrolysis, photolytic cleavage, oxidative degradation, decarboxylation, enantiomeric impurity, and so on. The different pharmacopoeias such as the British Pharmacopoeia, United State Pharmacopoeia, and Indian Pharmacopoeia are slowly incorporating limits to allowable levels of impurities present in APIs or formulations. Various methods are used to isolate and characterize impurities in pharmaceuticals, such as, capillary electrophoresis, electron paramagnetic resonance, gas-liquid chromatography, gravimetric analysis, high performance liquid chromatography, solid-phase extraction methods, liquid-liquid extraction method, Ultraviolet Spectrometry, infrared spectroscopy, supercritical fluid extraction column chromatography, mass spectrometry, Nuclear magnetic resonance (NMR spectroscopy, and RAMAN spectroscopy. Among all hyphenated techniques, the most exploited techniques for impurity profiling of drugs are Liquid Chromatography (LC-Mass Spectroscopy (MS, LC-NMR, LC-NMR-MS, GC-MS, and LC-MS. This reveals the need and scope of impurity profiling of drugs in pharmaceutical research.

  9. Some aspects regarding impurities profile in fipronil-HPLC method

    Directory of Open Access Journals (Sweden)

    Ana Csuma,

    2011-12-01

    Full Text Available Using a substance as active pharmaceutical ingredient in veterinary drug formulation requires the characterization of this substance as content in active compound and so in terms of impurities possiblepresent in it, the latter being a mandatory requirement for a drug application. Fipronil is a synthetic product belonging to pesticide class used in veterinary practice to manufacture of some products against fleas, given spot–on or in form of spray, in cats and dogs. The main impurities in fipronil include process related impuritiesand degradation products as a result of exposure to environmental conditions: reduction, oxidation, photolysis and hydrolysis. A HPLC method suitable for analytical separation of fipronil from its impurities was established. Separation was achieved on a reversed phase column using a mixture of methanol, acetonitrile and water as mobile phase. In the chosen chromatographic conditions the resolution between fipronil and its sulphone (the main impurity was > 3 and the tailing factor (T < 2.0. Related impurities have absorbed in thesame band of UV wavelength as the main compound fipronil. Comparing the area of impurities obtained for sample solution with the area of the main peak in diluted standard solution allowed the detection of impurities at concentration < 0.1 %. Chromatographic separation on the same analytical column and detection at 280 nm was validated for assay of the content of active substance in fipronil used as ingredient in drug formulations.

  10. The interface of the ferromagnetic metal CoS2 and the nonmagnetic semiconductor FeS2

    KAUST Repository

    Nazir, S.

    2010-11-05

    The electronic and magnetic properties of the cubic pyriteCoS2/FeS2interface are studied using the all-electron full-potential linearized augmented plane wave method. We find that this contact between a ferromagneticmetal and a nonmagnetic semiconductor shows a metallic character. The CoS2 stays close to half-metallicity at the interface, while the FeS2 becomes metallic. The magnetic moment of the Co atoms at the interface slightly decreases as compared to the bulk value and a small moment is induced on the Fe atoms. Furthermore, at the interfaceferromagnetic ordering is found to be energetically favorable as compared to antiferromagnetic ordering.

  11. Imaging of room-temperature ferromagnetic nano-domains at the surface of a non-magnetic oxide

    Science.gov (United States)

    Taniuchi, T.; Motoyui, Y.; Morozumi, K.; Rödel, T. C.; Fortuna, F.; Santander-Syro, A. F.; Shin, S.

    2016-06-01

    Two-dimensional electron gases at oxide surfaces or interfaces show exotic ordered states of matter, like superconductivity, magnetism or spin-polarized states, and are a promising platform for alternative oxide-based electronics. Here we directly image a dense population of randomly distributed ferromagnetic domains of ~40 nm typical sizes at room temperature at the oxygen-deficient surface of SrTiO3, a non-magnetic transparent insulator in the bulk. We use laser-based photoemission electron microscopy, an experimental technique that gives selective spin detection of the surface carriers, even in bulk insulators, with a high spatial resolution of 2.6 nm. We furthermore find that the Curie temperature in this system is as high as 900 K. These findings open perspectives for applications in nano-domain magnetism and spintronics using oxide-based devices, for instance through the nano-engineering of oxygen vacancies at surfaces or interfaces of transition-metal oxides.

  12. Non-Equilibrium Chemistry of Dynamically Evolving Prestellar Cores: I. Basic Magnetic and Non-Magnetic Models and Parameter Studies

    CERN Document Server

    Tassis, Konstantinos; Yorke, Harold W; Turner, Neal

    2011-01-01

    We combine dynamical and non-equilibrium chemical modeling of evolving prestellar molecular cloud cores, and explore the evolution of molecular abundances in the contracting core. We model both magnetic cores, with varying degrees of initial magnetic support, and non-magnetic cores, with varying collapse delay times. We explore, through a parameter study, the competing effects of various model parameters in the evolving molecular abundances, including the elemental C/O ratio, the temperature, and the cosmic-ray ionization rate. We find that different models show their largest quantitative differences at the center of the core, whereas the outer layers, which evolve slower, have abundances which are severely degenerate among different dynamical models. There is a large range of possible abundance values for different models at a fixed evolutionary stage (central density), which demonstrates the large potential of chemical differentiation in prestellar cores. However, degeneracies among different models, compou...

  13. Enhanced infrared magneto-optical response of the nonmagnetic semiconductor BiTeI driven by bulk Rashba splitting.

    Science.gov (United States)

    Demkó, L; Schober, G A H; Kocsis, V; Bahramy, M S; Murakawa, H; Lee, J S; Kézsmárki, I; Arita, R; Nagaosa, N; Tokura, Y

    2012-10-19

    We study the magneto-optical (MO) response of the polar semiconductor BiTeI with giant bulk Rashba spin splitting at various carrier densities. Despite being nonmagnetic, the material is found to yield a huge MO activity in the infrared region under moderate magnetic fields (up to 3 T). Our first-principles calculations show that the enhanced MO response of BiTeI comes mainly from the intraband transitions between the Rashba-split bulk conduction bands. These transitions connecting electronic states with opposite spin directions become active due to the presence of strong spin-orbit interaction and give rise to distinct features in the MO spectra with a systematic doping dependence. We predict an even more pronounced enhancement in the low-energy MO response and dc Hall effect near the crossing (Dirac) point of the conduction bands.

  14. Enhanced infrared magneto-optical response of the nonmagnetic semiconductor BiTeI driven by bulk Rashba splitting

    Energy Technology Data Exchange (ETDEWEB)

    Demko, L.; Tokura, Y. [Multiferroics Project, ERATO, JST, c/o Department of Applied Physics, University of Tokyo (Japan); Schober, G.A.H. [Institute for Theoretical Physics, University of Heidelberg (Germany); Kocsis, V.; Kezsmarki, I. [Department of Physics, Budapest University of Technology and Economics and Condensed Matter Research Group of the Hungarian Academy of Sciences (Hungary); Bahramy, M.S.; Murakawa, H. [CMRG and CERG, RIKEN ASI (Japan); Lee, J.S.; Arita, R.; Nagaosa, N. [Department of Applied Physics, University of Tokyo (Japan)

    2013-07-01

    We study the magneto-optical (MO) response of the polar semiconducting BiTeI with giant bulk Rashba spin splitting at various carrier densities. Despite being nonmagnetic, the material is found to yield a huge MO activity in the infrared region under moderate magnetic fields (up to 3 T). Our first-principles calculations show that the enhanced MO response of BiTeI comes mainly from the intraband transitions between the Rashba-split bulk conduction bands. These transitions connecting electronic states with opposite spin directions become active due to the presence of strong spin-orbit interaction and give rise to distinct features in the MO spectra with a systematic doping dependence. We predict an even more pronounced enhancement in the low-energy MO response and dc Hall effect near the crossing (Dirac) point of the conduction bands.

  15. First-principles study for vacancy-induced magnetism in nonmagnetic ferroelectric BaTiO3.

    Science.gov (United States)

    Cao, D; Cai, M Q; Zheng, Yue; Hu, W Y

    2009-12-14

    The possibilities of vacancy-induced magnetism in perovskite BaTiO(3) are investigated by first-principles calculations. Calculated results show that both titanium and oxygen vacancies could induce magnetism, but the barium vacancy did not induce magnetism. New and interesting magnetic properties of half-metallic magnetism are found in BaTiO(3) induced by the Ti-vacancy. Based on the density of states and the spin charge density distribution of BaTiO(3), we discuss the different origins of magnetism induced by the partial spin-polarized O 2p states around Ti vacancies and the partially filled d-states Ti around the oxygen vacancies. The discrepancy between the magnetic moments in the cubic phase and the tetragonal phase is due to anisotropic spin polarization induced by structure distortions. Our calculations would enable exploring magneto-electric coupling in nonmagnetic ferroelectric oxides.

  16. The non-magnetic collapsed tetragonal phase of CaFe2As2 and superconductivity in the iron pnictides

    Science.gov (United States)

    Soh, J. H.; Tucker, G. S.; Pratt, D. K.; Abernathy, D. L.; Stone, M. B.; Ran, S.; Bud'Ko, S. L.; Canfield, P. C.; Kreyssig, A.; McQueeney, R. J.; Goldman, A. I.

    2014-03-01

    The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the non-superconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is non-magnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds. Work at the Ames Laboratory was supported by the Department of Energy, Basic Energy Sciences. Work at ORNL's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences.

  17. Impurity-limited resistance and phase interference of localized impurities under quasi-one dimensional nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Nobuyuki, E-mail: sano@esys.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

    2015-12-28

    The impurity-limited resistance and the effect of the phase interference among localized multiple impurities in the quasi-one dimensional (quasi-1D) nanowire structures are systematically investigated under the framework of the scattering theory. We derive theoretical expressions of the impurity-limited resistance in the nanowire under the linear response regime from the Landauer formula and from the Boltzmann transport equation (BTE) with the relaxation time approximation. We show that the formula from the BTE exactly coincides with that from the Landauer approach with the weak-scattering limit when the energy spectrum of the in-coming electrons from the reservoirs is narrow and, thus, point out a possibility that the distinction of the impurity-limited resistances derived from the Landauer formula and that of the BTE could be made clear. The derived formulas are applied to the quasi-1D nanowires doped with multiple localized impurities with short-range scattering potential and the validity of various approximations on the resistance are discussed. It is shown that impurity scattering becomes so strong under the nanowire structures that the weak-scattering limit breaks down in most cases. Thus, both phase interference and phase randomization simultaneously play a crucial role in determining the impurity-limited resistance even under the fully coherent framework. When the impurity separation along the wire axis direction is small, the constructive phase interference dominates and the resistance is much greater than the average resistance. As the separation becomes larger, however, it approaches the series resistance of the single-impurity resistance due to the phase randomization. Furthermore, under the uniform configuration of impurities, the space-average resistance of multiple impurities at room temperature is very close to the series resistance of the single-impurity resistance, and thus, each impurity could be regarded as an independent scattering center. The

  18. Impurities that cause difficulty in stripping actinides from commercial tetraalkylcarbamoylmethylphosphonates

    Energy Technology Data Exchange (ETDEWEB)

    Bahner, C. T.; Shoun, R. R.; McDowell, W. J.

    1977-09-01

    Dihexyl((diethylcarbamoyl)methyl)phosphonate (DHDECMP) in diethylbenzene extracts actinides well from 6 M nitric acid solution, but commercially available DHDECMP contains impurities which interfere with stripping the actinides from the organic extract. DHDECMP purified by molecular distillation does not contain these impurities, but the pot residue contains increased concentrations of them. Heating the purified DHDECMP causes the formation of products which interfere with stripping in the same way, suggesting that high temperatures employed in the manufacture of DHDECMP may produce the offending impurities. These impurities can be separated from the heat-decomposed material or the pot residues by dilution with a large volume of hexanes (causing part of the impurities to separate as a second liquid phase) followed by equilibration of the hexane solution with dilute alkali. After the treatment with hexane and dilute alkali, the DHDECMP is readily recovered and functions well in the actinide extraction process. Dibutyl((dibutylcarbamoyl)methyl)-phosphonate (DBDBCMP) and di(2-ethylhexyl)((diethylcarbamoyl)-methyl)phosphonate (DEHDECMP) are purified less effectively by these methods. Similar separation methods using diethylbenzene or CCl/sub 4/ as solvent do not remove impurities as completely as the hexane process. Impurities can also be removed from a benzene solution of the DHDECMP pot residue by passing it through a column packed with silica gel or diethylaminoethyl cellulose. These impurities have been separated into fractions for analytical examination by use of various solvents and by column chromatography. Hexyl hydrogen ((diethylcarbamoyl)methyl)-phosphonate has been identified tentatively as a principal objectionable impurity. Dihexyl phosphoric acid and possibly dihexylphosphonate have been identified in other fractions.

  19. Impurity effects on trapped electron mode in tokamak plasmas

    Science.gov (United States)

    Du, Huarong; Wang, Zheng-Xiong; Dong, J. Q.

    2016-07-01

    The effects of impurity ions on the trapped electron mode (TEM) in tokamak plasmas are numerically investigated with the gyrokinetic integral eigenmode equation. It is shown that in the case of large electron temperature gradient ( η e ), the impurity ions have stabilizing effects on the TEM, regardless of peaking directions of their density profiles for all normalized electron density gradient R / L n e . Here, R is the major radius and L n e is the electron density gradient scale length. In the case of intermediate and/or small η e , the light impurity ions with conventional inwardly (outwardly) peaked density profiles have stabilizing effects on the TEM for large (small) R / L n e , while the light impurity ions with steep inwardly (outwardly) peaked density profiles can destabilize the TEM for small (large) R / L n e . Besides, the TEM driven by density gradient is stabilized (destabilized) by the light carbon or oxygen ions with inwardly (outwardly) peaked density profiles. In particular, for flat and/or moderate R / L n e , two independent unstable modes, corresponding respectively to the TEM and impurity mode, are found to coexist in plasmas with impurity ions of outwardly peaked density profiles. The high Z tungsten impurity ions play a stronger stabilizing role in the TEM than the low Z impurity ions (such as carbon and oxygen) do. In addition, the effects of magnetic shear and collision on the TEM instability are analyzed. It is shown that the collisionality considered in this work weakens the trapped electron response, leading to a more stable TEM instability, and that the stabilizing effects of the negative magnetic shear on the TEM are more significant when the impurity ions with outwardly peaked density profile are taken into account.

  20. Backoff-stage synchronization in three-hop string-topology wireless networks with hidden nodes

    Science.gov (United States)

    Sanada, Kosuke; Sekiya, Hiroo; Komuro, Nobuyoshi; Sakata, Shiro

    In IEEE 802.11 wireless multi-hop networks, each node works individually and their individual operations generate entire network dynamics. It is important to clarify the network dynamics in wireless multi-hop networks for designing and constructing multi-hop communication networks. This paper presents the network-dynamics investigations for three-hop string-topology wireless network in detail. From the investigations, a “backoff-stage synchronization” phenomenon, which is mutuality between hidden nodes, is found. The mechanism of the backoff-stage synchronization is expressed and the sufficient conditions for the synchronization occurrence are given. This phenomenon gives some impacts on the IEEE 802.11 multi-hop-network communications.

  1. Protein structure prediction: assembly of secondary structure elements by basin-hopping.

    Science.gov (United States)

    Hoffmann, Falk; Vancea, Ioan; Kamat, Sanjay G; Strodel, Birgit

    2014-10-20

    The prediction of protein tertiary structure from primary structure remains a challenging task. One possible approach to this problem is the application of basin-hopping global optimization combined with an all-atom force field. In this work, the efficiency of basin-hopping is improved by introducing an approach that derives tertiary structures from the secondary structure assignments of individual residues. This approach is termed secondary-to-tertiary basin-hopping and benchmarked for three miniproteins: trpzip, trp-cage and ER-10. For each of the three miniproteins, the secondary-to-tertiary basin-hopping approach successfully and reliably predicts their three-dimensional structure. When it is applied to larger proteins, correctly folded structures are obtained. It can be concluded that the assembly of secondary structure elements using basin-hopping is a promising tool for de novo protein structure prediction.

  2. Potential use ofGarcinia kola as hop substitute in lager beer brewing.

    Science.gov (United States)

    Aniche, G N; Uwakwe, G U

    1990-09-01

    The chemical, brewing and anti-microbial properties of a tropical seed,Garcinia kola, were compared with traditional hops. Treatment ofGarcinia kola with methanolic lead acetate produced a yellow precipitate from which organic acids (alpha acids) were contirmed to be present by thin-layer chromatography. Hops, however, had a higher concentration of organic acids thanGarcinia kola. Laboratory brewing trials withGarcinia kola and hops gave beers with simillar chemical properties. Organoleptically,Garcinia kola beer was as acceptable to tasters as hopped beer except that it had an improved bitterness.Garcinia kola and hop extracts exerted similar anti-microbial effects on two beer spollage micro-organisms (Lactobacillus delbruckii andCandida vini).

  3. Research on ADV-Hop localization algorithm in wireless sensor networks

    Science.gov (United States)

    Zhao, Shijun; Xu, Xiulan; Zhang, Zhaohui; Sun, Meiling

    2008-10-01

    Wireless sensor networks (WSN) have wide applicability to many important applications including environmental monitoring, military applications and disaster management, etc. In many applications, sensors are assumed to know their absolute locations. Some localization methods of WSN have been proposed. In these methods, nodes equipped with GPS to get precise location information, namely the anchor nodes, are employed to derive the locations of other nodes. Most of the recent work focuses on increasing the accuracy in position estimation. In this paper, aiming at the high communication cost and average positioning error of DV-hop algorithm, an advanced algorithm which is called ADV-hop algorithm is proposed. Simulations are made by the network simulator NS2. The simulation results show that ADV-hop algorithm has lower communication cost and smaller average positioning error than DV-hop algorithm, which makes ADV-hop algorithm more suitable for the node location of WSN.

  4. Long-range exchange interaction between magnetic impurities in graphene

    Science.gov (United States)

    Agarwal, M.; Mishchenko, E. G.

    2017-02-01

    The effective spin exchange RKKY coupling between impurities (adatoms) on graphene mediated by conduction electrons is studied as a function of the strength of the potential part of the on-site energy U of the electron-adatom interaction. With increasing U , the exchange coupling becomes long range, determined largely by the impurity levels with energies close to the Dirac points. When adatoms reside on opposite sublattices, their exchange coupling, normally antiferromagnetic, becomes ferromagnetic and resonantly enhanced at a specific distance where an impurity level crosses the Dirac point.

  5. Negative compressibility observed in graphene containing resonant impurities

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X. L.; Wang, L.; Li, W.; Wang, Y.; He, Y. H.; Wu, Z. F.; Han, Y.; Zhang, M. W.; Xiong, W.; Wang, N. [Department of Physics and The William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2013-05-20

    We observed negative compressibility in monolayer graphene containing resonant impurities under different magnetic fields. Hydrogenous impurities were introduced into graphene by electron beam (e-beam) irradiation. Resonant states located in the energy region of {+-}0.04 eV around the charge neutrality point were probed in e-beam-irradiated graphene capacitors. Theoretical results based on tight-binding and Lifshitz models agreed well with experimental observations of graphene containing a low concentration of resonant impurities. The interaction between resonant states and Landau levels was detected by varying the applied magnetic field. The interaction mechanisms and enhancement of the negative compressibility in disordered graphene are discussed.

  6. Generalized Wilson chain for solving multichannel quantum impurity problems

    Science.gov (United States)

    Mitchell, Andrew K.; Galpin, Martin R.; Wilson-Fletcher, Samuel; Logan, David E.; Bulla, Ralf

    2014-03-01

    The numerical renormalization group is used to solve quantum impurity problems, which describe magnetic impurities in metals, nanodevices, and correlated materials within dynamical mean field theory. Here we present a simple generalization of the Wilson chain, which improves the scaling of computational cost with the number of conduction bands, bringing more complex problems within reach. The method is applied to calculate the t matrix of the three-channel Kondo model at T =0, which shows universal crossovers near non-Fermi-liquid critical points. A nonintegrable three-impurity problem with three bands is also studied, revealing a rich phase diagram and novel screening and overscreening mechanisms.

  7. Thermal quantum discord in the Heisenberg chain with impurity

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Jia-Min, E-mail: jmgong@yeah.net; Hui, Zhan-Qiang

    2014-07-01

    We study thermal quantum discord (TQD) in the Heisenberg chain with spin site or magnetic impurity. The former one of which may induce inhomogeneous exchange interactions between the neighboring spins, while the latter one may model a spin chain with nonuniform magnetic field. In contrast to one's traditional understanding, we found that the spin impurity can be used to enhance the TQD greatly for all the bipartition schemes of the chain, while the magnetic impurity located on one spin can make the TQD between the other two spins approaching its maximum 1 for the antiferromagnetic chain.

  8. Exact Solution for Perk-Schultz Model with Boundary Impurities *

    Institute of Scientific and Technical Information of China (English)

    LI Guang-Liang; YUE Rui-Hong; SHI Kang-Jie; HOU Bo-Yu

    2001-01-01

    The Perk-Schultz model with SUq(m|n) spin boundary impurities is constructed by dressing the c-number reflecting K-matrix with the local L-matrix which acts non-trivially on an impurity Hilbert space. The eigenvalue of the transfer matrix and the corresponding Bethe ansatz equations with different c-number reflecting K-matrices are obtained by using the nested Bethe ansatz method (m ≠ n). When m = 1,n = 2, our results come back to that of supersymmetric t - J model with SUq(1|2) spin boundary impurities.

  9. RNAi knockdown of Hop (Hsp70/Hsp90 organising protein) decreases invasion via MMP-2 down regulation.

    Science.gov (United States)

    Walsh, Naomi; Larkin, AnneMarie; Swan, Niall; Conlon, Kevin; Dowling, Paul; McDermott, Ray; Clynes, Martin

    2011-07-28

    We previously identified Hop as over expressed in invasive pancreatic cancer cell lines and malignant tissues of pancreatic cancer patients, suggesting an important role for Hop in the biology of invasive pancreatic cancer. Hop is a co-chaperone protein that binds to both Hsp70/Hsp90. We hypothesised that by targeting Hop, signalling pathways modulating invasion and client protein stabilisation involving Hsp90-dependent complexes may be altered. In this study, we show that Hop knockdown by small interfering (si)RNA reduces the invasion of pancreatic cancer cells, resulting in decreased expression of the downstream target gene, matrix metalloproteinases-2 (MMP-2). Hop in conditioned media co-immunoprecipitates with MMP-2, implicating a possible extracellular function for Hop. Knockdown of Hop expression also reduced expression levels of Hsp90 client proteins, HER2, Bcr-Abl, c-MET and v-Src. Furthermore, Hop is strongly expressed in high grade PanINs compared to lower PanIN grades, displaying differential localisation in invasive ductal pancreatic cancer, indicating that the localisation of Hop is an important factor in pancreatic tumours. Our data suggests that the attenuation of Hop expression inactivates key signal transduction proteins which may decrease the invasiveness of pancreatic cancer cells possibly through the modulation of Hsp90 activity. Therefore, targeting Hop in pancreatic cancer may constitute a viable strategy for targeted cancer therapy.

  10. Engaging Black Males on Their Own Terms: What Schools Can Learn from Black Males Who Produce Hip-Hop

    Science.gov (United States)

    Irby, Decoteau J.; Petchauer, Emery; Kirkland, David

    2013-01-01

    Education scholars and practitioners have much to learn about engagement and motivation of Black males by directing their inquiries to more organic sites of hip-hop cultural production outside of schools. One such site is the hip-hop's informal labor economy where Black males engage in earning money through hip-hop cultural production. Labor…

  11. Involvement of Vacuolar Sequestration and Active Transport in Tolerance of Saccharomyces cerevisiae to Hop Iso-α-Acids

    NARCIS (Netherlands)

    Hazelwood, L.A.; Walsh, M.C.; Pronk, J.T.; Daran, J.M.

    2009-01-01

    The hop plant, Humulus lupulus L., has an exceptionally high content of secondary metabolites, the hop -acids, which possess a range of beneficial properties, including antiseptic action. Studies performed on the mode of action of hop iso--acids have hitherto been restricted to lactic acid bacteria.

  12. RNAi knockdown of Hop (Hsp70/Hsp90 organising protein) decreases invasion via MMP-2 down regulation.

    LENUS (Irish Health Repository)

    Walsh, Naomi

    2011-07-28

    We previously identified Hop as over expressed in invasive pancreatic cancer cell lines and malignant tissues of pancreatic cancer patients, suggesting an important role for Hop in the biology of invasive pancreatic cancer. Hop is a co-chaperone protein that binds to both Hsp70\\/Hsp90. We hypothesised that by targeting Hop, signalling pathways modulating invasion and client protein stabilisation involving Hsp90-dependent complexes may be altered. In this study, we show that Hop knockdown by small interfering (si)RNA reduces the invasion of pancreatic cancer cells, resulting in decreased expression of the downstream target gene, matrix metalloproteinases-2 (MMP-2). Hop in conditioned media co-immunoprecipitates with MMP-2, implicating a possible extracellular function for Hop. Knockdown of Hop expression also reduced expression levels of Hsp90 client proteins, HER2, Bcr-Abl, c-MET and v-Src. Furthermore, Hop is strongly expressed in high grade PanINs compared to lower PanIN grades, displaying differential localisation in invasive ductal pancreatic cancer, indicating that the localisation of Hop is an important factor in pancreatic tumours. Our data suggests that the attenuation of Hop expression inactivates key signal transduction proteins which may decrease the invasiveness of pancreatic cancer cells possibly through the modulation of Hsp90 activity. Therefore, targeting Hop in pancreatic cancer may constitute a viable strategy for targeted cancer therapy.

  13. Involvement of Vacuolar Sequestration and Active Transport in Tolerance of Saccharomyces cerevisiae to Hop Iso-α-Acids

    NARCIS (Netherlands)

    Hazelwood, L.A.; Walsh, M.C.; Pronk, J.T.; Daran, J.M.

    2009-01-01

    The hop plant, Humulus lupulus L., has an exceptionally high content of secondary metabolites, the hop -acids, which possess a range of beneficial properties, including antiseptic action. Studies performed on the mode of action of hop iso--acids have hitherto been restricted to lactic acid bacteria.

  14. On Clustering Impurities by Liquid Density Fluctuations

    Directory of Open Access Journals (Sweden)

    Alexander L. Shimkevich

    2010-01-01

    Full Text Available Recent developments in liquid technology have created a new class of fluids called “nanofluids” which are two-phase mixtures of a non-metal-liquid matrix and addon particles usually less than 100 nm in size. It is reputed that such liquids have a great potential for application. Indeed, many tests have shown that their thermal conductivity can be increased by almost 20% compared to that of the base fluids for a relatively low particle loading (of 1 up to 5% in volume. It is confirmed by experimental data and simulation results. In this study, the author considers an effect of impurity clustering by liquid density fluctuations as a natural mechanism for stabilizing microstructure of the colloidal solution and estimates the effect of fractal structure of colloidal particles on thermal conductivity of water. The results of this study may be useful for motivating choosing the composition of heat-transfer suspension and developing technology for making the appropriate nanofluid.

  15. Impurity trapped excitons under high hydrostatic pressure

    Science.gov (United States)

    Grinberg, Marek

    2013-09-01

    Paper summarizes the results on pressure effect on energies of the 4fn → 4fn and 4fn-15d1 → 4fn transitions as well as influence of pressure on anomalous luminescence in Lnα+ doped oxides and fluorides. A model of impurity trapped exciton (ITE) was developed. Two types of ITE were considered. The first where a hole is localized at the Lnα+ ion (creation of Ln(α+1)+) and an electron is attracted by Coulomb potential at Rydberg-like states and the second where an electron captured at the Lnα+ ion (creation of Ln(α-1)+) and a hole is attracted by Coulomb potential at Rydberg-like states. Paper presents detailed analysis of nonlinear changes of energy of anomalous luminescence of BaxSr1-xF2:Eu2+ (x > 0.3) and LiBaF3:Eu2+, and relate them to ITE-4f65d1 states mixing.

  16. Impurity Trapping of Positive Muons in Metals

    CERN Multimedia

    2002-01-01

    Polarized positive muons are implanted into metal samples. In an applied magnetic field the muon spin precession is studied. The line width in the precession frequency spectrum gives information about the static and dynamic properties of muons in a metal lattice. At temperatures where the muon is immobile within its lifetime the line width gives information about the site of location. At temperatures where the muon is mobile, the line width gives information on the diffusion process. It is known from experiments on quasi-elastic neutron scattering on hydrogen in niobium that interstitial impurities like nitrogen tend to act as traps for hydrogen. These trapping effects have now been studied systematically for muons in both f.c.c. metals (aluminium and copper) and b.c.c. metals (mainly niobium). Direct information on the trapping rates and the nature of the diffusion processes can be obtained since the muonic lifetime covers a time range where many of these processes occur.\\\\ \\\\ Mathematical models are set up ...

  17. An improved DV-Hop algorithm based on genetic algorithm%遗传算法的 DV-Hop 算法改进

    Institute of Scientific and Technical Information of China (English)

    张万礼; 宋启祥

    2015-01-01

    DV-Hop 算法中,平均每跳距离是影响定位精度的因素之一。针对平均每跳距离带来的定位误差,对锚节点和未知节点的平均每跳距离进行了改进和优化。首先引入遗传算法计算锚节点的平均每跳距离;然后利用跳数小于等于3的锚节点的平均每跳距离加权处理未知节点的平均每跳距离,减少平均每跳距离带来的误差。仿真结果表明,在不增加硬件开销的基础上,改进算法能够有效提高算法的定位精度,并且具有较好的稳定性。%The average per-hop distance is one of the factors which affect the positioning accuracy in DV-Hop algorithm.Aiming at positioning errors caused by the average distance per hop,the average distance per hop of anchor nodes and unknown nodes have been improved and optimized in this paper.First,the average per hop distance of anchor nodes is computed by introducing genetic algorithm;Then the average distance per hop of the unknown node is weighted by using the average distance per hop of anchor nodes which hop count is less than or equal to 3 to reduce errors caused average distance per hop.Ultimately the accuracy of positioning is improved.Simulation results show that without additional hardware cost,the improved algorithm can effectively improve the positioning accuracy of the algorithm and has good stability.

  18. Runaway electron dynamics in tokamak plasmas with high impurity content

    Science.gov (United States)

    Martín-Solís, J. R.; Loarte, A.; Lehnen, M.

    2015-09-01

    The dynamics of high energy runaway electrons is analyzed for plasmas with high impurity content. It is shown that modified collision terms are required in order to account for the collisions of the relativistic runaway electrons with partially stripped impurity ions, including the effect of the collisions with free and bound electrons, as well as the scattering by the full nuclear and the electron-shielded ion charge. The effect of the impurities on the avalanche runaway growth rate is discussed. The results are applied, for illustration, to the interpretation of the runaway electron behavior during disruptions, where large amounts of impurities are expected, particularly during disruption mitigation by massive gas injection. The consequences for the electron synchrotron radiation losses and the resulting runaway electron dynamics are also analyzed.

  19. Parallel impurity dynamics in the TJ-II stellarator

    CERN Document Server

    Alonso, J A; Estrada, T; Fontdecaba, J M; García-Regaña, J M; Geiger, J; Landreman, M; McCarthy, K J; Medina, F; Van Milligen, B Ph; Ochando, M A; Parra, F I; Velasco, J L

    2016-01-01

    We review in a tutorial fashion some of the causes of impurity density variations along field lines and radial impurity transport in the moment approach framework. An explicit and compact form of the parallel inertia force valid for arbitrary toroidal geometry and magnetic coordinates is derived and shown to be non-negligible for typical TJ-II plasma conditions. In the second part of the article, we apply the fluid model including main ion-impurity friction and inertia to observations of asymmetric emissivity patterns in neutral beam heated plasmas of the TJ-II stellarator. The model is able to explain qualitatively several features of the radiation asymmetry, both in stationary and transient conditions, based on the calculated in-surface variations of the impurity density.

  20. A bijection theorem for domino tiling with diagonal impurities

    CERN Document Server

    Nakano, Fumihiko

    2009-01-01

    We consider the dimer problem on a non-bipartite graph $G$, where there are two types of dimers one of which we regard impurities. Results of simulations using Markov chain seem to indicate that impurities are tend to distribute on the boundary, which we set as a conjecture. We first show that there is a bijection between the set of dimer coverings on $G$ and the set of spanning forests on two graphs which are made from $G$, with configuration of impurities satisfying a pairing condition. This bijection can be regarded as a extension of the Temperley bijection. We consider local move consisting of two operations, and by using the bijection mentioned above, we prove local move connectedness. We further obtained some bound of the number of dimer coverings and the probability finding an impurity at given edge, by extending the argument in our previous result.