WorldWideScience

Sample records for strong negative magnetic

  1. From Positive to Negative Zero-Field Splitting in a Series of Strongly Magnetically Anisotropic Mononuclear Metal Complexes.

    Science.gov (United States)

    Novitchi, Ghénadie; Jiang, Shangda; Shova, Sergiu; Rida, Fatima; Hlavička, Ivo; Orlita, Milan; Wernsdorfer, Wolfgang; Hamze, Rana; Martins, Cyril; Suaud, Nicolas; Guihéry, Nathalie; Barra, Anne-Laure; Train, Cyrille

    2017-12-18

    A series of mononuclear [M(hfa) 2 (pic) 2 ] (Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; pic = 4-methylpyridine; M = Fe II , Co II , Ni II , Zn II ) compounds were obtained and characterized. The structures of the complexes have been resolved by single-crystal X-ray diffraction, indicating that, apart from the zinc derivative, the complexes are in a trans configuration. Moreover, a dramatic lenghthening of the Fe-N distances was observed, whereas the nickel(II) complex is almost perfectly octahedral. The magnetic anisotropy of these complexes was thoroughly studied by direct-current (dc) magnetic measurements, high-field electron paramagnetic resonance, and infrared (IR) magnetospectroscopy: the iron(II) derivative exhibits an out-of-plane anisotropy (D Fe = -7.28 cm -1 ) with a high rhombicity, whereas the cobalt(II) and nickel(II) complexes show in-plane anisotropy (D Co ∼ 92-95 cm -1 ; D Ni = 4.920 cm -1 ). Ab initio calculations were performed to rationalize the evolution of the structure and identify the excited states governing the magnetic anisotropy along the series. For the iron(II) complex, an out-of-phase alternating-current (ac) magnetic susceptibility signal was observed using a 0.1 T dc field. For the cobalt(II) derivative, the ac magnetic susceptibility shows the presence of two field-dependent relaxation phenomena: at low field (500 Oe), the relaxation process is beyond single-ion behavior, whereas at high field (2000 Oe), the relaxation of magnetization implies several mechanisms including an Orbach process with U eff = 25 K and quantum tunneling of magnetization. The observation by μ-SQUID magnetization measurements of hysteresis loops of up to 1 K confirmed the single-ion-magnet behavior of the cobalt(II) derivative.

  2. Negative magnetic relaxation in superconductors

    Directory of Open Access Journals (Sweden)

    Krasnoperov E.P.

    2013-01-01

    Full Text Available It was observed that the trapped magnetic moment of HTS tablets or annuli increases in time (negative relaxation if they are not completely magnetized by a pulsed magnetic field. It is shown, in the framework of the Bean critical-state model, that the radial temperature gradient appearing in tablets or annuli during a pulsed field magnetization can explain the negative magnetic relaxation in the superconductor.

  3. Strong and superstrong pulsed magnetic fields generation

    CERN Document Server

    Shneerson, German A; Krivosheev, Sergey I

    2014-01-01

    Strong pulsed magnetic fields are important for several fields in physics and engineering, such as power generation and accelerator facilities. Basic aspects of the generation of strong and superstrong pulsed magnetic fields technique are given, including the physics and hydrodynamics of the conductors interacting with the field as well as an account of the significant progress in generation of strong magnetic fields using the magnetic accumulation technique. Results of computer simulations as well as a survey of available field technology are completing the volume.

  4. Strong negative terahertz photoconductivity in photoexcited graphene

    Science.gov (United States)

    Fu, Maixia; Wang, Xinke; Ye, Jiasheng; Feng, Shengfei; Sun, Wenfeng; Han, Peng; Zhang, Yan

    2018-01-01

    Terahertz (THz) response of a chemical vapor deposited graphene on a quartz substrate has been investigated by using an ultrafast optical-pump THz-probe spectroscopy. Without photoexcitation, the frequency-dependence optical conductivity shows a strong carrier response owing to the intrinsically doped graphene. Upon photoexcitation, an enhancement in THz transmission is observed and the transmission increases nonlinearly with the increase of pump power, which is rooted in a reduction of intrinsic conductivity arising from the strong enhancement of carrier scattering rather than THz emission occurrence. The modulation depth of 18.8% was experimentally achieved, which is more than four times greater than that of the previous reported. The photoinduced response here highlights the variety of response possible in graphene depending on the sample quality, carrier mobility and doping level. The graphene provides promising applications in high-performance THz modulators and THz photoelectric devices.

  5. Giant negative thermal expansion in magnetic nanocrystals.

    Science.gov (United States)

    Zheng, X G; Kubozono, H; Yamada, H; Kato, K; Ishiwata, Y; Xu, C N

    2008-12-01

    Most solids expand when they are heated, but a property known as negative thermal expansion has been observed in a number of materials, including the oxide ZrW2O8 (ref. 1) and the framework material ZnxCd1-x(CN)2 (refs 2,3). This unusual behaviour can be understood in terms of low-energy phonons, while the colossal values of both positive and negative thermal expansion recently observed in another framework material, Ag3[Co(CN)6], have been explained in terms of the geometric flexibility of its metal-cyanide-metal linkages. Thermal expansion can also be stopped in some magnetic transition metal alloys below their magnetic ordering temperature, a phenomenon known as the Invar effect, and the possibility of exploiting materials with tuneable positive or negative thermal expansion in industrial applications has led to intense interest in both the Invar effect and negative thermal expansion. Here we report the results of thermal expansion experiments on three magnetic nanocrystals-CuO, MnF2 and NiO-and find evidence for negative thermal expansion in both CuO and MnF2 below their magnetic ordering temperatures, but not in NiO. Larger particles of CuO and MnF2 also show prominent magnetostriction (that is, they change shape in response to an applied magnetic field), which results in significantly reduced thermal expansion below their magnetic ordering temperatures; this behaviour is not observed in NiO. We propose that the negative thermal expansion effect in CuO (which is four times larger than that observed in ZrW2O8) and MnF2 is a general property of nanoparticles in which there is strong coupling between magnetism and the crystal lattice.

  6. Thermodynamical instabilities under strong magnetic fields

    Science.gov (United States)

    Chen, Y. J.

    2017-03-01

    The thermodynamical instabilities of low densities in the n p matter and n p e matter are studied within several relativistic nuclear models under some values of magnetic fields. The results are compared between each other and the effects of the symmetry energy slope at saturation density on the instability are investigated. The instability regions can exhibit bands due to the presence of Landau levels for very strong magnetic fields of the order of 1017 G, while for weaker magnetic fields, the bands are replaced by many diffused or scattered pieces. It also shows that the proton fraction in the inner crust of neutron stars may be complex under strong magnetic fields.

  7. Hydrogen atoms in a strong magnetic field

    International Nuclear Information System (INIS)

    Santos, R.R. dos.

    1975-07-01

    The energies and wave functions of the 14 lowest states of a Hydrogen atom in a strong magnetic field are calculated, using a variational scheme. The equivalence between the atomic problem and the problems related with excitons and impurities in semiconductors in the presence of a strong magnetic field are shown. The calculations of the energies and wave functions have been divided in two regions: the first, for the magnetic field ranging between zero and 10 9 G; in the second the magnetic field ranges between 10 9 and 10 11 G. The results have been compared with those obtained by previous authors. The computation time necessary for the calculations is small. Therefore this is a convenient scheme to obtain the energies and wave functions for the problem. Transition probabilities, wavelengths and oscillator strengths for some allowed transitions are also calculated. (Author) [pt

  8. Bound states in a strong magnetic field

    International Nuclear Information System (INIS)

    Machado, C. S.; Navarra, F. S.; Noronha, J.; Oliveira, E. G.; Ferreira Filho, L. G.

    2013-01-01

    We expect a strong magnetic field to be produced in the perpendicular direction to the reaction plane, in a noncentral heavy-ion collision . The strength of the magnetic field is estimated to be eB∼m 2 π ∼ 0.02 GeV 2 at the RHIC and eB∼ 15m 2 π ∼ 0.3 GeV 2 at the LHC. We investigate the effects of the magnetic field on B 0 and D 0 mesons, focusing on the changes of the energy levels and of the mass of the bound states.

  9. Nonlinear Electron Waves in Strongly Magnetized Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans; Juul Rasmussen, Jens

    1980-01-01

    Weakly nonlinear dispersive electron waves in strongly magnetized plasma are considered. A modified nonlinear Schrodinger equation is derived taking into account the effect of particles resonating with the group velocity of the waves (nonlinear Landau damping). The possibility of including the ion...

  10. Weak and strong nonlinearities in magnetic bearings

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav

    2004-01-01

    Roč. 39, č. 7 (2004), s. 779-795 ISSN 0094-114X R&D Projects: GA ČR GA101/00/1471; GA AV ČR IBS2076301 Institutional research plan: CEZ:AV0Z2076919 Keywords : weak nonlinearitiy * strong nonlinearity * magnetics bearings Subject RIV: BI - Acoustics Impact factor: 0.605, year: 2004

  11. Mechanics of magnetic fluid column in strong magnetic fields

    International Nuclear Information System (INIS)

    Polunin, V.M.; Ryapolov, P.A.; Platonov, V.B.

    2017-01-01

    Elastic-and magnetic properties of magnetic fluid confined by ponderomotive force in a tube fixed in horizontal position are considered. The system is placed in a strong magnetic field under the influence of external static and dynamic perturbations. An experimental setup has been developed. A theoretical basis of the processes of magnetic colloid elastic deformation has been proposed. The values of the static ponderomotive elasticity coefficient and the elasticity coefficient under dynamic action are experimentally determined. The calculations of the saturation magnetization for two magnetic fluid samples, carried out according to the equation containing the dynamic elasticity coefficient, are in good agreement with the experimental magnetization curve. The described method is of interest when studying magnetophoresis and aggregation of nanoparticles in magnetic colloids.

  12. Neutrino oscillations in strong magnetic fields

    International Nuclear Information System (INIS)

    Likhachev, G.G.; Studenikin, A.I.

    1994-07-01

    Neutrino conversion processes between two neutrino species and the corresponding oscillations induced by strong magnetic fields are considered. The value of the critical strength of magnetic field B cr as a function of characteristics of neutrinos in vacuum (Δm 2 ν , mixing angle θ), effective particle density of matter n eff , neutrino (transition) magnetic moment μ-tilde and energy E is introduced. It is shown that the neutrino conversion and oscillations effects induced by magnetic fields B ≥ B cr are important and may result in the depletion of the initial type of ν's in the bunch. A possible increase of these effects in the case when neutrinos pass through a sudden decrease of density of matter (''cross-boundary effect'') and applications to neutrinos from neutron stars and supernova are discussed. (author). 25 refs

  13. Frictional Coulomb drag in strong magnetic fields

    DEFF Research Database (Denmark)

    Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang

    1997-01-01

    A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21) is eval......A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21......) is evaluated using diagrammatic techniques. The transresistivity is given by an integral over energy and momentum transfer weighted by the product of the screened interlayer interaction and the phase space for scattering events. We demonstrate, by a numerical analysis of the transresistivity, that for well...

  14. Magnetic properties of strongly asymmetric nuclear matter

    International Nuclear Information System (INIS)

    Kutschera, M.; Wojcik, W.

    1988-01-01

    We investigate stability of neutron matter containing a small proton admixture with respect to spin fluctuations. We establish conditions under which strongly asymmetric nuclear matter could acquire a permanent magnetization. It is shown that if the protons are localized, the system becomes unstable to spin fluctuations for arbitrarily weak proton-neutron spin interactions. For non-localized protons there exists a threshold value of the spin interaction above which the system can develop a spontaneous polarization. 12 refs., 2 figs. (author)

  15. Super-strong Magnetic Field in Sunspots

    Science.gov (United States)

    Okamoto, Takenori J.; Sakurai, Takashi

    2018-01-01

    Sunspots are the most notable structure on the solar surface with strong magnetic fields. The field is generally strongest in a dark area (umbra), but sometimes stronger fields are found in non-dark regions, such as a penumbra and a light bridge. The formation mechanism of such strong fields outside umbrae is still puzzling. Here we report clear evidence of the magnetic field of 6250 G, which is the strongest field among Stokes I profiles with clear Zeeman splitting ever observed on the Sun. The field was almost parallel to the solar surface and located in a bright region sandwiched by two opposite-polarity umbrae. Using a time series of spectral data sets, we discuss the formation process of the super-strong field and suggest that this strong field region was generated as a result of compression of one umbra pushed by the horizontal flow from the other umbra, such as the subduction of the Earth’s crust in plate tectonics.

  16. Strong Turbulence in Alkali Halide Negative Ion Plasmas

    Science.gov (United States)

    Sheehan, Daniel

    1999-11-01

    Negative ion plasmas (NIPs) are charge-neutral plasmas in which the negative charge is dominated by negative ions rather than electrons. They are found in laser discharges, combustion products, semiconductor manufacturing processes, stellar atmospheres, pulsar magnetospheres, and the Earth's ionosphere, both naturally and man-made. They often display signatures of strong turbulence^1. Development of a novel, compact, unmagnetized alkali halide (MX) NIP source will be discussed, it incorporating a ohmically-heated incandescent (2500K) tantulum solenoid (3cm dia, 15 cm long) with heat shields. The solenoid ionizes the MX vapor and confines contaminant electrons, allowing a very dry (electron-free) source. Plasma densities of 10^10 cm-3 and positive to negative ion mass ratios of 1 Fusion 4, 91 (1978).

  17. Negative mobility of a Brownian particle: Strong damping regime

    Science.gov (United States)

    Słapik, A.; Łuczka, J.; Spiechowicz, J.

    2018-02-01

    We study impact of inertia on directed transport of a Brownian particle under non-equilibrium conditions: the particle moves in a one-dimensional periodic and symmetric potential, is driven by both an unbiased time-periodic force and a constant force, and is coupled to a thermostat of temperature T. Within selected parameter regimes this system exhibits negative mobility, which means that the particle moves in the direction opposite to the direction of the constant force. It is known that in such a setup the inertial term is essential for the emergence of negative mobility and it cannot be detected in the limiting case of overdamped dynamics. We analyse inertial effects and show that negative mobility can be observed even in the strong damping regime. We determine the optimal dimensionless mass for the presence of negative mobility and reveal three mechanisms standing behind this anomaly: deterministic chaotic, thermal noise induced and deterministic non-chaotic. The last origin has never been reported. It may provide guidance to the possibility of observation of negative mobility for strongly damped dynamics which is of fundamental importance from the point of view of biological systems, all of which in situ operate in fluctuating environments.

  18. Strongly Interacting Matter in Magnetic Field

    Science.gov (United States)

    Mao, Shijun; Wu, Youjia; Zhuang, Pengfei

    Inverse magnetic catalysis effect on the chiral phase transition is investigated in the frame of SU(2) NJL model with Pauli-Villars regularization scheme. We consider two scenarios, the chiral chemical potential μ5 caused by sphalerons and magnetic inhibition of mesons π0. With different chiral chemical potential, we always obtain magnetic catalysis in the mean field calculation, due to the enhancement of Fermi surface of the pairing fermions by μ5. On the other hand, when going beyond the mean field approximation by including the feed-down from mesons to quarks, the competition between the magnetic catalysis effect of quarks and magnetic inhibition effect of mesons leads to the transition from inverse magnetic catalysis to delayed magnetic catalysis with increasing magnetic field.

  19. Mechanism and Simulation of Generating Pulsed Strong Magnetic Field

    Science.gov (United States)

    Yang, Xian-Jun; Wang, Shuai-Chuang; Deng, Ai-Dong; Gu, Zhuo-Wei; Luo, Hao

    2014-10-01

    A strong magnetic field (over 1000 T) was recently experimentally produced at the Academy of Engineering Physics in China. The theoretical methods, which include a simple model and MHD code, are discussed to investigate the physical mechanism and dynamics of generating the strong magnetic field. The analysis and simulation results show that nonlinear magnetic diffusion contributes less as compared to the linear magnetic diffusion. This indicates that the compressible hydrodynamic effect and solid imploding compression may have a large influence on strong magnetic field generation.

  20. Effective magnetic moment of neutrinos in strong magnetic fields

    CERN Document Server

    Pérez, A; Masood, S S; Gaitan, R; Rodríguez, S

    2002-01-01

    In this paper we compute the effective magnetic moment of neutrinos propagating in dense high magnetized medium. Taking typical values of magnetic field and densities of astrophysical objects (such as the cores of supernovae and neutron stars) we obtain an effective type of dipole magnetic moment in agreement with astrophysical and cosmological bounds. (Author)

  1. Activity of Strongly Magnetized Neutron Stars

    Science.gov (United States)

    Beloborodov, Andrei

    This proposal is the continuation of a previous 3-year project that focused on modeling the nonthermal emission from magnetars and pulsars and testing the models against new observations, in particular by NuSTAR. The proposed project develops in two directions: (1) First-principle simulations of the magnetospheric electron-positron discharge using our code APERTURE (based on the particle-in-cell method), which is specifically designed for this purpose. Its performance is demonstrated by the first application to rotation-powered pulsars, and it can significantly advance our understanding of the magnetospheric activity of magnetars and pulsars. Our simulations involve a detailed implementation of radiative processes, tracking the emission and propagation of gammarays and production of electron-positron pairs. The results will provide new theoretical foundation for interpreting emission from the twisted magnetospheres of neutron stars. They will clarify, in particular, the radiative mechanism of magnetar bursts and persistent emission. (2) Investigation of magnetic field evolution inside neutron stars, which is ultimately responsible for driving the magnetospheric activity of magnetars and their surface heating. Our recent results suggest two novel phenomena in the solid crust of an active magnetar: thermoplastic waves and Hall-mediated avalanches. We propose to investigate scenarios for the global magnetic field evolution in the core and the crust, and its observables including (a) twisting of the external magnetosphere and the resulting nonthermal activity, (b) subsurface heating, and (c) sudden changes of the rotation rate. We will use our models and the rich accumulated data to disentangle the key dynamic processes inside magnetars. This analysis can constrain the magnetic fields hidden inside magnetars, the state of their core matter and its possible superfluidity.

  2. Strong permanent magnet-assisted electromagnetic undulator

    Science.gov (United States)

    Halbach, Klaus

    1988-01-01

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

  3. Enhanced thermal photon and dilepton production in strongly coupled = 4 SYM plasma in strong magnetic field

    Science.gov (United States)

    Mamo, Kiminad A.

    2013-08-01

    We calculate the DC conductivity tensor of strongly coupled = 4 super-Yang-Mills (SYM) plasma in a presence of a strong external magnetic field B ≫ T 2 by using its gravity dual and employing both the RG flow approach and membrane paradigm which give the same results. We find that, since the magnetic field B induces anisotropy in the plasma, different components of the DC conductivity tensor have different magnitudes depending on whether its components are in the direction of the magnetic field B. In particular, we find that a component of the DC conductivity tensor in the direction of the magnetic field B increases linearly with B while the other components (which are not in the direction of the magnetic field B) are independent of it. These results are consistent with the lattice computations of the DC conductivity tensor of the QCD plasma in an external magnetic field B. Using the DC conductivity tensor, we calculate the soft or low-frequency thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in the presence of the strong external magnetic field B ≫ T 2. We find that the strong magnetic field B enhances both the thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in a qualitative agreement with the experimentally observed enhancements at the heavy-ion collision experiments.

  4. STRONG SOLAR WIND DYNAMIC PRESSURE PULSES: INTERPLANETARY SOURCES AND THEIR IMPACTS ON GEOSYNCHRONOUS MAGNETIC FIELDS

    International Nuclear Information System (INIS)

    Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Xie, Yanqiong; Xu, Xiaojun

    2015-01-01

    In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector

  5. Electrostatic turbulence in strongly magnetized plasmas

    International Nuclear Information System (INIS)

    Nielsen, A.H.

    1993-01-01

    Turbulence in plasmas has been investigated experimentally and numerically. On the experimental side the turbulent nature of the Kelvin-Helmholtz instability has been studied in a single-ended Q-machine. The development of coherent structures in the background of the turbulent flow has been demonstrated and the capability of structures of transporting plasma across the magnetic field-lines is explained in detail. The numerical investigations are divided into two parts: Numerical simulations of the dynamics from the Q-machine experiments using spectral methods to solve the two-dimensional Navier-Stokes equations in a cylindrical geometry. A numerical study of the Eulerian-Lagrangian transformation in a two-dimensional flow. Here the flow is made up by a large number of structures, where each individual structure is convected by the superposed flow field of all the others. (au) (33 ills., 67 refs.)

  6. Operating a magnetic nozzle helicon thruster with strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Kazunori, E-mail: kazunori@ecei.tohoku.ac.jp; Komuro, Atsushi; Ando, Akira [Department of Electrical Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2016-03-15

    A pulsed axial magnetic field up to ∼2.8 kG is applied to a 26-mm-inner-diameter helicon plasma thruster immersed in a vacuum chamber, and the thrust is measured using a pendulum target. The pendulum is located 30-cm-downstream of the thruster, and the thruster rf power and argon flow rate are fixed at 1 kW and 70 sccm (which gives a chamber pressure of 0.7 mTorr). The imparted thrust increases as the applied magnetic field is increased and saturates at a maximum value of ∼9.5 mN for magnetic field above ∼2 kG. At the maximum magnetic field, it is demonstrated that the normalized plasma density, and the ion flow energy in the magnetic nozzle, agree within ∼50% and of 10%, respectively, with a one-dimensional model that ignores radial losses from the nozzle. This magnetic nozzle model is combined with a simple global model of the thruster source that incorporates an artificially controlled factor α, to account for radial plasma losses to the walls, where α = 0 and 1 correspond to zero losses and no magnetic field, respectively. Comparison between the experiments and the model implies that the radial losses in the thruster source are experimentally reduced by the applied magnetic field to about 10% of that obtained from the no magnetic field model.

  7. Electromagnetic modes in cold magnetized strongly coupled plasmas

    OpenAIRE

    Tkachenko, I. M.; Ortner, J.; Rylyuk, V. M.

    1999-01-01

    The spectrum of electromagnetic waves propagating in a strongly coupled magnetized fully ionized hydrogen plasma is found. The ion motion and damping being neglected, the influence of the Coulomb coupling on the electromagnetic spectrum is analyzed.

  8. Spectral confinement and current for atoms in strong magnetic fields

    DEFF Research Database (Denmark)

    Fournais, Søren

    2007-01-01

    e study confinement of the ground state of atoms in strong magnetic fields to different subspaces related to the lowest Landau band. Using the results on confinement we can calculate the quantum current in the entire semiclassical region B<3......e study confinement of the ground state of atoms in strong magnetic fields to different subspaces related to the lowest Landau band. Using the results on confinement we can calculate the quantum current in the entire semiclassical region B

  9. Transport Theory for Plasmas that are Strongly Magnetized and Strongly Coupled

    Science.gov (United States)

    Baalrud, Scott; Daligault, Jerome

    2016-10-01

    Plasmas with components that are magnetized, strongly coupled, or both arise in a variety of frontier plasma physics experiments including magnetized dusty plasmas, nonneutral plasmas, magnetized ICF concepts, as well as from self-generated fields in ICF. Here, a species is considered strongly magnetized if the gyroradius is smaller than the spatial scale over which Coulomb interactions occur. A theory for transport properties is described that treats a wide range of both coupling and magnetization strengths. The approach is based on an extension of the recent effective potential transport theory to include a strong magnetic field. The underlying kinetic theory is based on an extension of the Boltzmann equation to include a strong magnetic field in the dynamics of binary scattering events. Corresponding magnetohydrodynamic equations are derived by solving the kinetic equation using a Chapman-Enskog like spectral method. Results are compared with classical molecular dynamics simulations of self-diffusion of the one component plasmas, and with simulations of parallel to perpendicular temperature equilibration of an initially anisotropic distribution. This material is based upon work supported by AFOSR Award FA9550-16-1-0221 and DOE OFES Award DE-SC0016159.

  10. Radial oscillations of neutron stars in strong magnetic fields

    Indian Academy of Sciences (India)

    The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained from the relativistic nuclear mean field theory is taken and extended to ...

  11. Radial oscillations of neutron stars in strong magnetic fields

    Indian Academy of Sciences (India)

    Abstract. The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained from the relativistic nuclear mean field theory is taken and ...

  12. Magnetic separation technique for environmental water purification by strong magnetic field generator loading HTS bulk magnets

    International Nuclear Information System (INIS)

    Oka, T.; Tanaka, K.; Kimura, T.; Mimura, D.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Yokoyama, K.; Yamaguchi, M.

    2010-01-01

    The magnetic separation technique in combination with high temperature superconducting bulk magnets has been investigated to purify the ground water which has been used in the coolant system for the incinerator furnace to cool the burning gas. The experiment has been operated by means of the newly-built alternating channel type magnetic separating device. The separation ratios of ferromagnetic flocks including fine magnetite powder have been estimated by means of the high gradient magnetic separation method with small iron balls filled in the water channels. As the magnetic force acting on the magnetic particle is given by the product of a magnetization of the material and a gradient of magnetic field, and as the ferromagnetic stainless steel balls yield the steep gradient of magnetic field around them in a strong magnetic field, the system has exhibited a quite excellent performance with respect to the separation ratios. The separation ratios of the flocks which contain the magnetite powder with the values more than 50 ppm have remained over 80% for under the flow rates less than 5 L/min.

  13. Magnetic separation technique for environmental water purification by strong magnetic field generator loading HTS bulk magnets

    Science.gov (United States)

    Oka, T.; Tanaka, K.; Kimura, T.; Mimura, D.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Yokoyama, K.; Yamaguchi, M.

    2010-11-01

    The magnetic separation technique in combination with high temperature superconducting bulk magnets has been investigated to purify the ground water which has been used in the coolant system for the incinerator furnace to cool the burning gas. The experiment has been operated by means of the newly-built alternating channel type magnetic separating device. The separation ratios of ferromagnetic flocks including fine magnetite powder have been estimated by means of the high gradient magnetic separation method with small iron balls filled in the water channels. As the magnetic force acting on the magnetic particle is given by the product of a magnetization of the material and a gradient of magnetic field, and as the ferromagnetic stainless steel balls yield the steep gradient of magnetic field around them in a strong magnetic field, the system has exhibited a quite excellent performance with respect to the separation ratios. The separation ratios of the flocks which contain the magnetite powder with the values more than 50 ppm have remained over 80% for under the flow rates less than 5 L/min.

  14. LDA+DMFT Approach to Magnetocrystalline Anisotropy of Strong Magnets

    Directory of Open Access Journals (Sweden)

    Jian-Xin Zhu

    2014-05-01

    Full Text Available The new challenges posed by the need of finding strong rare-earth-free magnets demand methods that can predict magnetization and magnetocrystalline anisotropy energy (MAE. We argue that correlated electron effects, which are normally underestimated in band-structure calculations, play a crucial role in the development of the orbital component of the magnetic moments. Because magnetic anisotropy arises from this orbital component, the ability to include correlation effects has profound consequences on our predictive power of the MAE of strong magnets. Here, we show that incorporating the local effects of electronic correlations with dynamical mean-field theory provides reliable estimates of the orbital moment, the mass enhancement, and the MAE of YCo_{5}.

  15. Ion Motion in a Plasma Interacting with Strong Magnetic Fields

    International Nuclear Information System (INIS)

    Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtmant, A.

    1999-01-01

    The interaction of a plasma with strong magnetic fields takes place in many laboratory experiments and astrophysical plasmas. Applying a strong magnetic field to the plasma may result in plasma displacement, magnetization, or the formation of instabilities. Important phenomena in plasma, such as the energy transport and the momentum balance, take a different form in each case. We study this interaction in a plasma that carries a short-duration (80-ns) current pulse, generating a magnetic field of up to 17 kG. The evolution of the magnetic field, plasma density, ion velocities, and electric fields are determined before and during the current pulse. The dependence of the plasma limiting current on the plasma density and composition are studied and compared to theoretical models based on the different phenomena. When the plasma collisionality is low, three typical velocities should be taken into consideration: the proton and heavier-ion Alfven velocities (v A p and v A h , respectively) and the EMHD magnetic-field penetration velocity into the plasma (v EMHD ). If both Alfven velocities are larger than v EMHD the plasma is pushed ahead of the magnetic piston and the magnetic field energy is dissipated into ion kinetic energy. If v EMHD is the largest of three velocities, the plasma become magnetized and the ions acquire a small axial momentum only. Different ion species may drift in different directions along the current lines. In this case, the magnetic field energy is probably dissipated into electron thermal energy. When vs > V EMHD > vi, as in the case of one of our experiments, ion mass separation occurs. The protons are pushed ahead of the piston while the heavier-ions become magnetized. Since the plasma electrons are unmagnetized they cannot cross the piston, and the heavy ions are probably charge-neutralized by electrons originating from the cathode that are 'born' magnetized

  16. Vortex-lattice states at strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Akera, H.; MacDonald, A.H.; Girvin, S.M. (Department of Physics, Indiana University, Bloomington, Indiana (USA)); Norman, M.R. (Materials Science Division, Argonne National Laboratory, Argonne, Illinois (USA))

    1991-10-21

    At strong magnetic fields, Landau quantization invalidates the semiclassical approximations which underly the Ginzburg-Landau (GL) theory of the mixed states of type-II superconductors. We have solved the {ital microscopic} mean-field equations for the case of a two-dimensional electron system in the strong magnetic-field limit. For delta-function attractive interactions there exist {ital n}+1 pairing channels in the {ital n}th Landau level. For {ital n}{gt}0, two channels share the maximum {ital T}{sub {ital c}}, and the order parameter differs markedly from expectations based on GL theory.

  17. Confinining properties of QCD in strong magnetic backgrounds

    Directory of Open Access Journals (Sweden)

    Bonati Claudio

    2017-01-01

    Full Text Available Strong magnetic backgrounds are known to modify QCD properties at a nonperturbative level. We discuss recent lattice results, obtained for Nf = 2 + 1 QCD with physical quark masses, concerning in particular the modifications and the anisotropies induced at the level of the static quark-antiquark potential, both at zero and finite temperature.

  18. Theory of Spin Waves in Strongly Anisotropic Magnets

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Cooke, J. F.

    1976-01-01

    A new infinite-order perturbation approach to the theory of spin waves in strongly anisotropic magnets is introduced. The system is transformed into one with effective two-ion anisotropy and considerably reduced ground-state corrections. A general expression for the spin-wave energy, valid to any...

  19. Resonances of the helium atom in a strong magnetic field

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Al-Hujaj, Omar-Alexander; Schmelcher, Peter

    2007-01-01

    We present an investigation of the resonances of a doubly excited helium atom in a strong magnetic field covering the regime B=0–100  a.u. A full-interaction approach which is based on an anisotropic Gaussian basis set of one-particle functions being nonlinearly optimized for each field strength...

  20. Observation of strong magnetic effects in visible-infrared sum frequency generation from magnetic structures

    NARCIS (Netherlands)

    Kirilyuk, A.; Knippels, G.M.H.; van der Meer, A. F. G.; Renard, S.; Rasing, T.; Heskamp, I. R.; Lodder, J. C.

    2000-01-01

    We have observed very strong magnetization-induced changes of the infrared-visible sum-frequency generation (SFG) intensity from thin magnetic films using a free electron laser as a tunable infrared source. With the help of a magnetic grating a clear resonance is observed due to the excitation of

  1. Neutrino-electron processes in a strongly magnetized thermal plasma

    CERN Document Server

    Hardy, S J; Hardy, Stephen J.; Thoma, Markus H.

    2001-01-01

    We present a new method of calculating the rate of neutrino-electron interactions in a strong magnetic field based on finite temperature field theory. Using this method, in which the effect of the magnetic field on the electron states is taken into account exactly, we calculate the rates of all of the lowest order neutrino-electron interactions in a plasma. As an example of the use of this technique, we explicitly calculate the rate at which neutrinos and antineutrinos annihilate in a highly magnetized plasma, and compare that to the rate in an unmagnetized plasma. The most important channel for energy deposition is the gyromagnetic absorption of a neutrino-antineutrino pair on an electron or positron in the plasma ($\

  2. Magnetic properties of metallic impurities with strongly correlated electrons

    Czech Academy of Sciences Publication Activity Database

    Janiš, Václav; Ringel, Matouš

    2009-01-01

    Roč. 115, č. 1 (2009), s. 30-35 ISSN 0587-4246 R&D Projects: GA ČR GA202/07/0644 Institutional research plan: CEZ:AV0Z10100520 Keywords : And erson impurity * strong electron correlations * spin-polarized solution * three-channel parquet equations * magnetic field Subject RIV: BE - Theoretical Physics Impact factor: 0.433, year: 2009 http://przyrbwn.icm.edu.pl/APP/ABSTR/115/a115-1-5.html

  3. Semicalssical quantization of interacting anyons in a strong magnetic field

    International Nuclear Information System (INIS)

    Levit, S.; Sivan, N.

    1992-01-01

    We represent a semiclassical theory of charged interacting anyons in strong magnetic fields. We apply this theory to a number of few anyons systems including two interacting anyons in the presence of an impurity and three interacting anyons. We discuss the dependence of their energy levels on the statistical parameter and find regions in which this dependence follows very different patterns. The semiclassical arguments allow to correlate these patterns with the change in the character of the classical motion of the system. (author)

  4. Strongly Coupled Magnetic and Electronic Transitions in Multivalent Strontium Cobaltites.

    Science.gov (United States)

    Lee, J H; Choi, Woo Seok; Jeen, H; Lee, H-J; Seo, J H; Nam, J; Yeom, M S; Lee, H N

    2017-11-22

    The topotactic phase transition in SrCoO x (x = 2.5-3.0) makes it possible to reversibly transit between the two distinct phases, i.e. the brownmillerite SrCoO 2.5 that is a room-temperature antiferromagnetic insulator (AFM-I) and the perovskite SrCoO 3 that is a ferromagnetic metal (FM-M), owing to their multiple valence states. For the intermediate x values, the two distinct phases are expected to strongly compete with each other. With oxidation of SrCoO 2.5 , however, it has been conjectured that the magnetic transition is decoupled to the electronic phase transition, i.e., the AFM-to-FM transition occurs before the insulator-to-metal transition (IMT), which is still controversial. Here, we bridge the gap between the two-phase transitions by density-functional theory calculations combined with optical spectroscopy. We confirm that the IMT actually occurs concomitantly with the FM transition near the oxygen content x = 2.75. Strong charge-spin coupling drives the concurrent IMT and AFM-to-FM transition, which fosters the near room-T magnetic transition characteristic. Ultimately, our study demonstrates that SrCoO x is an intriguingly rare candidate for inducing coupled magnetic and electronic transition via fast and reversible redox reactions.

  5. Achieving a strongly negative scattering asymmetry factor in random media composed of dual-dipolar particles

    Science.gov (United States)

    Wang, B. X.; Zhao, C. Y.

    2018-02-01

    Understanding radiative transfer in random media like micro- or nanoporous and particulate materials, allows people to manipulate the scattering and absorption of radiation, as well as opens new possibilities in applications such as imaging through turbid media, photovoltaics, and radiative cooling. A strong-backscattering phase function, i.e., a negative scattering asymmetry parameter g , is of great interest, which can possibly lead to unusual radiative transport phenomena, for instance, Anderson localization of light. Here we demonstrate that by utilizing the structural correlations and second Kerker condition for a disordered medium composed of randomly distributed silicon nanoparticles, a strongly negative scattering asymmetry factor (g ˜-0.5 ) for multiple light scattering can be realized in the near infrared. Based on the multipole expansion of Foldy-Lax equations and quasicrystalline approximation (QCA), we have rigorously derived analytical expressions for the effective propagation constant and scattering phase function for a random system containing spherical particles, by taking the effect of structural correlations into account. We show that as the concentration of scattering particles rises, the backscattering is also enhanced. Moreover, in this circumstance, the transport mean free path is largely reduced and even becomes smaller than that predicted by independent scattering approximation. We further explore the dependent scattering effects, including the modification of electric and magnetic dipole excitations and far-field interference effect, both induced and influenced by the structural correlations, for volume fraction of particles up to fv˜0.25 . Our results have profound implications in harnessing micro- or nanoscale radiative transfer through random media.

  6. Negative tunneling magneto-resistance in quantum wires with strong spin-orbit coupling.

    Science.gov (United States)

    Han, Seungju; Serra, Llorenç; Choi, Mahn-Soo

    2015-07-01

    We consider a two-dimensional magnetic tunnel junction of the FM/I/QW(FM+SO)/I/N structure, where FM, I and QW(FM+SO) stand for a ferromagnet, an insulator and a quantum wire with both magnetic ordering and Rashba spin-orbit (SOC), respectively. The tunneling magneto-resistance (TMR) exhibits strong anisotropy and switches sign as the polarization direction varies relative to the quantum-wire axis, due to interplay among the one-dimensionality, the magnetic ordering, and the strong SOC of the quantum wire.

  7. Helium atoms and molecules in strong magnetic fields

    Science.gov (United States)

    Mori, K.

    Recent theoretical studies have shown that the neutron star surface may be composed of helium or heavier elements as hydrogen may be quickly depleted by diffuse nuclear burning Chang Bildsten However while Hydrogen atmospheres have been studied in great details atomic data for helium is available only for He ion Pavlov Bezchastnov 2005 We performed Hartree-Fock type calculation for Helium atom and molecules and computed their binding ionization and dissociation energies in strong magnetic fields B sim10 12 -- 10 15 G We will present ionization balance of Helium atmospheres at typical magnetic field strengths and temperatures to radio-quiet neutron stars and AXPs We will also discuss several implications of helium atmosphere to X-ray data of isolated neutron stars focusing on the detected spectral features

  8. Debunking vaccination myths: strong risk negations can increase perceived vaccination risks.

    Science.gov (United States)

    Betsch, Cornelia; Sachse, Katharina

    2013-02-01

    Information about risks is often contradictory, especially in the health domain. A vast amount of bizarre information on vaccine-adverse events (VAE) can be found on the Internet; most are posted by antivaccination activists. Several actors in the health sector struggle against these statements by negating claimed risks with scientific explanations. The goal of the present work is to find optimal ways of negating risk to decrease risk perceptions. In two online experiments, we varied the extremity of risk negations and their source. Perception of the probability of VAE, their expected severity (both variables serve as indicators of perceived risk), and vaccination intentions. Paradoxically, messages strongly indicating that there is "no risk" led to a higher perceived vaccination risk than weak negations. This finding extends previous work on the negativity bias, which has shown that information stating the presence of risk decreases risk perceptions, while information negating the existence of risk increases such perceptions. Several moderators were also tested; however, the effect occurred independently of the number of negations, recipient involvement, and attitude. Solely the credibility of the information source interacted with the extremity of risk negation: For credible sources (governmental institutions), strong and weak risk negations lead to similar perceived risk, while for less credible sources (pharmaceutical industries) weak negations lead to less perceived risk than strong negations. Optimal risk negation may profit from moderate rather than extreme formulations as a source's trustworthiness can vary.

  9. Confinement and αs in a strong magnetic field

    Directory of Open Access Journals (Sweden)

    Yu.A. Simonov

    2015-07-01

    Full Text Available Hadron decay widths are shown to increase in strong magnetic fields as Γ(eB∼eBκΓ(0. The same mechanism is shown to be present in the production of the sea quark pair inside the confining string, which decreases the string tension with the growing eB parallel to the string. On the other hand, the average energy of the qq¯ holes in the string world sheet increases, when the direction of B is perpendicular to the sheet. These two effects stipulate the spectacular picture of the B dependent confinement and αs, discovered on the lattice.

  10. Bound states in strongly correlated magnetic and electronic systems

    International Nuclear Information System (INIS)

    Trebst, S.

    2002-02-01

    A novel strong coupling expansion method to calculate two-particle spectra of quantum lattice models is developed. The technique can be used to study bosonic and fermionic models and in principle it can be applied to systems in any dimension. A number of strongly correlated magnetic and electronic systems are examined including the two-leg spin-half Heisenberg ladder, the dimerized Heisenberg chain with a frustrating next-nearest neighbor interaction, coupled Heisenberg ladders, and the one-dimensional Kondo lattice model. In the various models distinct bound states are found below the two-particle continuum. Quantitative calculations of the dispersion, coherence length and binding energy of these bound states are used to describe spectroscopic experiments on (Ca,La) 14 Cu 24 O 41 and NaV 2 O 5 . (orig.)

  11. Quark-gluon plasma in strong magnetic fields

    International Nuclear Information System (INIS)

    Kalaydzhyan, Tigran

    2013-04-01

    One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.

  12. Strong enhancement of magnetic anisotropy energy in alloyed nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Negulyaev, Nikolay; Niebergall, Larissa; Stepanyuk, Valeri [Max-Planck-Institut fuer Mikrostrukturphysik, D-06120 Halle (Germany); Juarez Reyes, Lucila; Pastor, Gustavo [Institut fuer Theoretische Physik, Universitaet Kassel, D-34132 Kassel (Germany); Dorantes-Davila, Jesus [Instituto de Fisica, Universidad Autonoma de San Luis Potosi, 78000 San Luis Potosi (Mexico)

    2011-07-01

    One-dimensional atomic structures (monatomic wires and chains) are believed to be likely candidates for creation of nanostructures with large atomic orbital moments and hence with giant magnetic anisotropy energy (MAE) per atom. We investigate the possibility of tuning the MAE of 3d transition metal monowires alloyed with 5d elements (Ir, Pt). Our ab initio studies give clear evidence that in mixed 3d-5d atomic wires MAE is one and even two orders of magnitude more than in pure wires constructed of the corresponding 5d and 3d elements, respectively. Mechanisms responsible for the formation of such a strong MAE are revealed. The interplay between the structure of a monowire and its MAE is demonstrated. The contribution of both types of species (3d and 5d) into the MAE is discussed.

  13. Quark-gluon plasma in strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Kalaydzhyan, Tigran

    2013-04-15

    One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.

  14. Anomalous electrodynamics of neutral pion matter in strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, Tomáš [Department of Mathematics and Natural Sciences, University of Stavanger,N-4036 Stavanger (Norway); Kadam, Saurabh V. [Indian Institute of Science Education and Research (IISER),Pune 411008 (India)

    2017-03-03

    The ground state of quantum chromodynamics in sufficiently strong external magnetic fields and at moderate baryon chemical potential is a chiral soliton lattice (CSL) of neutral pions https://arxiv.org/abs/1609.05213. We investigate the interplay between the CSL structure and dynamical electromagnetic fields. Our main result is that in presence of the CSL background, the two physical photon polarizations and the neutral pion mix, giving rise to two gapped excitations and one gapless mode with a nonrelativistic dispersion relation. The nature of this mode depends on the direction of its propagation, interpolating between a circularly polarized electromagnetic wave https://www.doi.org/10.1103/PhysRevD.93.085036 and a neutral pion surface wave, which in turn arises from the spontaneously broken translation invariance. Quite remarkably, there is a neutral-pion-like mode that remains gapped even in the chiral limit, in seeming contradiction to the Goldstone theorem. Finally, we have a first look at the effect of thermal fluctuations of the CSL, showing that even the soft nonrelativistic excitation does not lead to the Landau-Peierls instability. However, it leads to an anomalous contribution to pressure that scales with temperature and magnetic field as T{sup 5/2}(B/f{sub π}){sup 3/2}.

  15. Observation of magnetization reversal and negative magnetization in Sr2YbRuO6

    International Nuclear Information System (INIS)

    Singh, Ravi P; Tomy, C V

    2008-01-01

    Detailed magnetic properties of the compound Sr 2 YbRuO 6 are presented here. The compound belongs to the family of double perovskites forming a monoclinic structure. Magnetization measurements reveal clear evidence for two components of magnetic ordering aligned opposite to each other, leading to a magnetization reversal, compensation temperature (T* = 34 K) and negative magnetization at low temperatures and low magnetic fields. Heat capacity measurements corroborate the presence of two components in the magnetic ordering and a noticeable third anomaly at low temperatures (∼15 K) which cannot be attributed the Schottky effect. The calculated magnetic entropy is substantially lower than that expected for the ground states of the ordered moments of Ru 5+ and Yb 3+ , indicating the presence of large crystal field effects and/or incomplete magnetic ordering and/or magnetic frustrations well above the magnetic ordering. An attempt is made to explain the magnetization reversal within the frameworks of available models

  16. Strong negative self regulation of Prokaryotic transcription factors increases the intrinsic noise of protein expression

    Directory of Open Access Journals (Sweden)

    Jenkins Dafyd J

    2008-01-01

    Full Text Available Abstract Background Many prokaryotic transcription factors repress their own transcription. It is often asserted that such regulation enables a cell to homeostatically maintain protein abundance. We explore the role of negative self regulation of transcription in regulating the variability of protein abundance using a variety of stochastic modeling techniques. Results We undertake a novel analysis of a classic model for negative self regulation. We demonstrate that, with standard approximations, protein variance relative to its mean should be independent of repressor strength in a physiological range. Consequently, in that range, the coefficient of variation would increase with repressor strength. However, stochastic computer simulations demonstrate that there is a greater increase in noise associated with strong repressors than predicted by theory. The discrepancies between the mathematical analysis and computer simulations arise because with strong repressors the approximation that leads to Michaelis-Menten-like hyperbolic repression terms ceases to be valid. Because we observe that strong negative feedback increases variability and so is unlikely to be a mechanism for noise control, we suggest instead that negative feedback is evolutionarily favoured because it allows the cell to minimize mRNA usage. To test this, we used in silico evolution to demonstrate that while negative feedback can achieve only a modest improvement in protein noise reduction compared with the unregulated system, it can achieve good improvement in protein response times and very substantial improvement in reducing mRNA levels. Conclusion Strong negative self regulation of transcription may not always be a mechanism for homeostatic control of protein abundance, but instead might be evolutionarily favoured as a mechanism to limit the use of mRNA. The use of hyperbolic terms derived from quasi-steady-state approximation should also be avoided in the analysis of stochastic

  17. Anomalous transport phenomena in Fermi liquids with strong magnetic fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Kontani, Hiroshi [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2008-02-15

    In this paper, we present recent developments in the theory of transport phenomena based on the Fermi liquid theory. In conventional metals, various transport coefficients are scaled according to the quasiparticles relaxation time, {tau}, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems. The most famous example would be high-T{sub c} superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. This issue has been one of the most significant unresolved problems in HTSCs for a long time. Similar anomalous transport phenomena have been observed in metals near their antiferromagnetic (AF) quantum critical point (QCP). The main goal of this study is to demonstrate whether the anomalous transport phenomena in HTSC is evidence of a non-Fermi liquid ground state, or just RTA violation in strongly correlated Fermi liquids. Another goal is to establish a unified theory of anomalous transport phenomena in metals with strong magnetic fluctuations. For these purposes, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. In a Fermi liquid, an excited quasiparticle induces other excited quasiparticles by collision, and current due to these excitations is called a current vertex correction (CVC). Landau noticed the existence of CVC first, which is indispensable for calculating transport coefficients in accord with the conservation laws. Here, we develop a transport theory involving resistivity and the Hall coefficient on the basis of the microscopic Fermi liquid theory, by considering the CVC. In nearly AF Fermi liquids, we find that the strong backward scattering due to AF fluctuations induces the CVC with prominent momentum dependence. This feature of the CVC can account for the significant enhancement in the Hall coefficient

  18. Anomalous transport phenomena in Fermi liquids with strong magnetic fluctuations

    International Nuclear Information System (INIS)

    Kontani, Hiroshi

    2008-01-01

    In this paper, we present recent developments in the theory of transport phenomena based on the Fermi liquid theory. In conventional metals, various transport coefficients are scaled according to the quasiparticles relaxation time, τ, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems. The most famous example would be high-T c superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. This issue has been one of the most significant unresolved problems in HTSCs for a long time. Similar anomalous transport phenomena have been observed in metals near their antiferromagnetic (AF) quantum critical point (QCP). The main goal of this study is to demonstrate whether the anomalous transport phenomena in HTSC is evidence of a non-Fermi liquid ground state, or just RTA violation in strongly correlated Fermi liquids. Another goal is to establish a unified theory of anomalous transport phenomena in metals with strong magnetic fluctuations. For these purposes, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. In a Fermi liquid, an excited quasiparticle induces other excited quasiparticles by collision, and current due to these excitations is called a current vertex correction (CVC). Landau noticed the existence of CVC first, which is indispensable for calculating transport coefficients in accord with the conservation laws. Here, we develop a transport theory involving resistivity and the Hall coefficient on the basis of the microscopic Fermi liquid theory, by considering the CVC. In nearly AF Fermi liquids, we find that the strong backward scattering due to AF fluctuations induces the CVC with prominent momentum dependence. This feature of the CVC can account for the significant enhancement in the Hall coefficient, magnetoresistance

  19. The realization of strong, stray static magnetic fields

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2012-01-01

    Roč. 9, č. 1 (2012), s. 71-77 ISSN 1214-9705 Institutional research plan: CEZ:AV0Z30460519 Keywords : magnetic fields * magnetic circuits * permanent NdFeB magnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/materialy/acta_content/2012_01/7_Zezulka.pdf

  20. Application of orbital strong magnet in the extraction of deep orbital magnetic foreign bodies

    Directory of Open Access Journals (Sweden)

    Jin-Chen Jia

    2017-12-01

    Full Text Available AIM: To investigate the surgical method and efficacy of extraction of deep orbital magnetic foreign bodies by mean of an orbital strong magnet. METHODS: A retrospective analysis of clinical data of patients with deep orbital magnetic foreign bodies(OMFBin Hebei Eye Hospital from June 2014 to May 2017 was processed. A total of 23 eyes were enrolled, among them, 14 eyes of extraorbital OMFB, 9 eyes of intraorbital OMFB. The rate of extraction of foreign bodies and the postoperative complications were observed. RESULTS: All eyes of intraorbital foreign bodies were successfully extracted with 100% success rate. Twelve of 14 eyes of extraorbital foreign bodies were extracted with 86% success rate. Mild orbital hemorrhage were found in 2 eyes. There was no other obvious complication such as visual loss, orbital massive hemorrhage or limited ocular movement. CONCLUSION: It's an ideal surgical method to extract the deep orbital magnetic foreign bodies by mean of an orbital strong magnet, with mini-injury, high success rate, short duration and few complications.

  1. Ion H2+ can dissociate in a strong magnetic field

    International Nuclear Information System (INIS)

    Turbiner, A.V.; Lopez, J.C.; Flores-Riveros, A.

    2001-01-01

    In framework of a variational method the molecular ion H 2 + in a magnetic field is studied. An optimal form of the vector potential corresponding to a given magnetic field is chosen. It is shown that for any magnetic field strength as well as for any orientation of the molecular axis the system (ppe) possesses a minimum in the potential energy. The stable configuration always corresponds to elongation along the magnetic line. However, for magnetic fields B ≥ 5 x 10 11 G and some orientations the ion H 2 + becomes instable decaying to H-atom + p [ru

  2. Nanosized helical magnetic domains in strongly frustrated Fe3PO4O3

    Science.gov (United States)

    Ross, K. A.; Bordelon, M. M.; Terho, G.; Neilson, J. R.

    2015-10-01

    Fe3PO4O3 forms a noncentrosymmetric lattice structure (space group R 3 m ) comprising triangular motifs of Fe3 + coupled by strong antiferromagnetic interactions (| ΘC W|>900 K). Neutron diffraction from polycrystalline samples shows that strong frustration eventually gives way to an ordered helical incommensurate structure below TN = 163 K, with the helical axis in the hexagonal a b plane and a modulation length to ˜86 Å. The magnetic structure consists of an unusual needlelike correlation volume that extends past 900 Å along the hexagonal c axis but is limited to ˜70 Å in the a b plane, despite the three-dimensional nature of the magnetic sublattice topology. The small in-plane correlation length, which persists to at least T =TN/40 , indicates a robust blocking of long-range order of the helical magnetic structure, and therefore stable domain walls, or other defect spin textures, must be abundant in Fe3PO4O3 . Temperature-dependent neutron powder diffraction reveals small negative thermal expansion below TN. No change in lattice symmetry is observed on cooling through TN, as revealed by high-resolution synchrotron x-ray diffraction. The previously reported reduced moment of the Fe3 + ions (S =5 /2 ), μ ˜4.2 μB , is confirmed here through magnetization studies of a magnetically diluted solid solution series of compounds, Fe(3 -x )GaxPO4O3 , and is consistent with the refined magnetic moment from neutron diffraction 4.14(2) μB. We attribute the reduced moment to a modified spin density distribution arising from ligand charge transfer in this insulating oxide.

  3. Chiral spiral induced by a strong magnetic field

    Directory of Open Access Journals (Sweden)

    Abuki Hiroaki

    2016-01-01

    Full Text Available We study the modification of the chiral phase structure of QCD due to an external magnetic field. We first demonstrate how the effect of magnetic field can systematically be incorporated into a generalized Ginzburg-Landau framework. We then analyze the phase structure in the vicinity of the chiral critical point. In the chiral limit, the effect is found to be so drastic that it brings a “continent” of chiral spiral in the phase diagram, by which the chiral tricritical point is totally washed out. This is the case no matter how small the intensity of magnetic field is. On the other hand, the current quark mass protects the chiral critical point from a weak magnetic field. However, the critical point will eventually be covered by the chiral spiral phase as the magnetic field grows.

  4. The permanent magnet systems generating strong stray fields with large localization region

    International Nuclear Information System (INIS)

    Samofalov, V.N.; Belozorov, D.P.; Ravlik, A.G.

    2008-01-01

    Three systems of permanent magnets, which produce strong magnetic stray fields (SFs) with H>B r =4πM r were studied in this work. Remarkable feature of the developed systems is localization of the strong fields in large region with linear dimension Δr comparable to characteristic magnet dimension a. The first system composed of uniformly magnetized magnets generates sufficiently homogeneous strong SFs, which amounts up to 1.5 of magnets induction B r . The second system with nonuniform magnetization is represented by cylindrical and hemispheric magnets their magnetization vector directed at every point along the radius. Such distribution of magnetization is assumed to be the consequence of magnet radial crystal texture resulting in a high uniaxial anisotropy field H K . It is shown that maximal SFs can exist on the flat surface of cylindrical magnet at the distance r from its axis and their limiting value equals to 4πM r ln(2a/r). Here, the localization region of the fields is comparable to diameter of cylindrical magnet Δr∼2R. As for the hemisphere its SFs are less than corresponding SFs for the cylinder. The third so-called quasi-nonuniform system consists of uniformly magnetized cylindrical sectors their magnetization vector is directed along the sector bisectrix. The strong SFs and their localization region are calculated in details for this case. The passage to radial magnetized cylinder is considered

  5. Intrinsic spin-relaxation induced negative tunnel magnetoresistance in a single-molecule magnet

    Science.gov (United States)

    Xie, Haiqing; Wang, Qiang; Xue, Hai-Bin; Jiao, HuJun; Liang, J.-Q.

    2013-06-01

    We investigate theoretically the effects of intrinsic spin-relaxation on the spin-dependent transport through a single-molecule magnet (SMM), which is weakly coupled to ferromagnetic leads. The tunnel magnetoresistance (TMR) is obtained by means of the rate-equation approach including not only the sequential but also the cotunneling processes. It is shown that the TMR is strongly suppressed by the fast spin-relaxation in the sequential region and can vary from a large positive to slight negative value in the cotunneling region. Moreover, with an external magnetic field along the easy-axis of SMM, a large negative TMR is found when the relaxation strength increases. Finally, in the high bias voltage limit the TMR for the negative bias is slightly larger than its characteristic value of the sequential region; however, it can become negative for the positive bias caused by the fast spin-relaxation.

  6. Magnetic dynamics of weakly and strongly interacting hematite nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Bender Koch, Christian; Mørup, Steen

    2000-01-01

    The magnetic dynamics of two differently treated samples of hematite nanoparticles from the same batch with a particle size of about 20 nm have been studied by Mossbauer spectroscopy. The dynamics of the first sample, in which the particles are coated and dispersed in water, is in accordance.......3(-0.8)(+1.0) x 10(-10) s for a rotation of the sublattice magnetization directions in the rhombohedral (111) plane. The corresponding median superparamagnetic blocking temperature is about 150 K. The dynamics of the second, dry sample, in which the particles are uncoated and thus allowed to aggregate, is slowed...... down by interparticle interactions and a magnetically split spectrum is retained at room temperature. The temperature variation or the magnetic hyperfine field, corresponding to different quantiles in the hyperfine field distribution, can be consistently described by a mean field model...

  7. Neutron star in the presence of strong magnetic field

    Indian Academy of Sciences (India)

    Stars: neutron stars; magnetic fields; equation of state. PACS Nos 26.60.Kp; 52.35.Tc; 97.10.Cv. 1. Introduction. The central density of neutron stars (NS) exceeds the nuclear saturation density (n0 ∼. 0.15 fm. −3. ), thereby giving the idea that compact stars might contain deconfined and chirally restored quark matter in them.

  8. How strongly are the magnetic anisotropy and coordination numbers ...

    Indian Academy of Sciences (India)

    Coordination number around the lanthanide ion is found to alter the magnetic behaviour of all the lanthanide complexes studied and this is contrary to the general belief that the lanthanide ions are inert and exert small ligand field interaction.High symmetric low-coordinate LnIII complexes are found to yield large Ueff values ...

  9. Cigar-shaped quarkonia under strong magnetic field

    Science.gov (United States)

    Suzuki, Kei; Yoshida, Tetsuya

    2016-03-01

    Heavy quarkonia in a homogeneous magnetic field are analyzed by using a potential model with constituent quarks. To obtain anisotropic wave functions and corresponding eigenvalues, the cylindrical Gaussian expansion method is applied, where the anisotropic wave functions are expanded by a Gaussian basis in the cylindrical coordinates. Deformation of the wave functions and the mass shifts of the S-wave heavy quarkonia (ηc, J /ψ , ηc(2 S ), ψ (2 S ) and bottomonia) are examined for the wide range of external magnetic field. The spatial structure of the wave functions changes drastically as adjacent energy levels cross each other. Possible observables in heavy-ion collision experiments and future lattice QCD simulations are also discussed.

  10. Strong magnetic field induces superconductivity in a Weyl semimetal

    Science.gov (United States)

    Rosenstein, Baruch; Shapiro, B. Ya.; Li, Dingping; Shapiro, I.

    2017-12-01

    Microscopic theory of the normal-to-superconductor coexistence line of a multiband Weyl superconductor subjected to magnetic field is constructed. It is shown that the Weyl semimetal that is nonsuperconducting or having a small critical temperature Tc at zero field might become a superconductor at higher temperatures when the magnetic field is tuned to a series of quantized values Hn. The pairing occurs on Landau levels. It is argued that the phenomenon is detectable much easier in Weyl semimetals than in parabolic band metals since the quantum limit already has been approached in several Weyl materials. The effect of Zeeman coupling leading to splitting of the reentrant superconducting regions on the magnetic phase diagram is considered. An experimental signature of the superconductivity on Landau levels is the reduction of magnetoresistivity. This has been observed already in Cd3As2 and several other compounds. The novel kind of quantum oscillations of magnetoresistance detected in ZrTe5 is discussed along these lines.

  11. Sensitivity Analysis and Simulation of Theoretical Response of Ceramics to Strong Magnetic Fields

    Science.gov (United States)

    2016-09-01

    448. 23. Song Q, Zhang ZJ. Shape control and associated magnetic properties of spinel cobalt ferrite nanocrystals. Journal of the American Chemical...Strong Magnetic Fields by Carli A Moorehead, Michael M Kornecki, Victoria L Blair, Raymond E Brennan Approved for... Magnetic Fields by Carli A Moorehead Drexel University, Philadelphia, Pennsylvannia Michael M Kornecki, Victoria L Blair, and Raymond E Brennan

  12. A strong angular dependence of magnetic properties of magnetosome chains: Implications for rock magnetism and paleomagnetism

    Science.gov (United States)

    Li, Jinhua; Ge, Kunpeng; Pan, Yongxin; Williams, Wyn; Liu, Qingsong; Qin, Huafeng

    2013-10-01

    Single-domain magnetite particles produced by magnetotactic bacteria (magnetosomes) and aligned in chains are of great interest in the biosciences and geosciences. Here, we investigated angular variation of magnetic properties of aligned Magnetospirillum magneticum AMB-1 cells, each of which contains one single fragmental chain of magnetosomes. With measurements at increasing angles from the chain direction, we observed that (i) the hysteresis loop gradually changes from nearly rectangular to a ramp-like shape (e.g., Bc and remanence decrease), (ii) the acquisition and demagnetization curves of IRM shift toward higher fields (e.g., Bcr increases), and (iii) the FORC diagram shifts toward higher coercivity fields (e.g., Bc,FORC increases). For low-temperature results, compared to unoriented samples, the samples containing aligned chains have a much lower remanence loss of field-cooled (δFC) and zero-field-cooled (δZFC) remanence upon warming through the Verwey transition, higher δ-ratio (δ = δFC/δZFC) for the measurement parallel to the chain direction, and lower δ-ratio, larger δFC and δZFC values for the perpendicular measurement. Micromagnetic simulations confirm the experimental observations and reveal that the magnetization reversal of magnetosome chain appears to be noncoherent at low angles and coherent at high angles. The simulations also demonstrate that the angular dependence of magnetic properties is related to the dispersion degree of individual chains, indicating that effects of anisotropy need to be accounted for when using rock magnetism to identify magnetosomes or magnetofossils once they have been preserved in aligned chains. Additionally, this study experimentally demonstrates an empirical correspondence of the parameter Bc,FORC to Bcr rather than Bc, at least for magnetite chains with strong shape anisotropy. This suggests FORC analysis is a good discriminant of magnetofossils in sediments and rocks.

  13. A strong permanent magnet-assisted electromagnetic undulator

    Science.gov (United States)

    Halbach, K.

    1987-01-30

    This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles. 4 figs.

  14. Sharp-front wave of strong magnetic field diffusion in solid metal

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bo; Gu, Zhuo-wei; Kan, Ming-xian; Wang, Gang-hua; Zhao, Jian-heng [Institute of Fluid Physics, CAEP, P.O. Box 919-105, Mianyang 621900 (China)

    2016-08-15

    When a strong magnetic field diffuses into a solid metal, if the metal's resistance possesses an abrupt rise at some critical temperature and the magnetic field strength is above some critical value, the magnetic field will diffuse into the metal in the form of a sharp-front wave. Formulas for the critical conditions under which a sharp-front magnetic diffusion wave emerges and a formula for the wave-front velocity are derived in this work.

  15. One-loop QCD thermodynamics in a strong homogeneous and static magnetic field

    Science.gov (United States)

    Rath, Shubhalaxmi; Patra, Binoy Krishna

    2017-12-01

    We have studied how the equation of state of thermal QCD with two light flavors is modified in a strong magnetic field. We calculate the thermodynamic observables of hot QCD matter up to one-loop, where the magnetic field affects mainly the quark contribution and the gluon part is largely unaffected except for the softening of the screening mass. We have first calculated the pressure of a thermal QCD medium in a strong magnetic field, where the pressure at fixed temperature increases with the magnetic field faster than the increase with the temperature at constant magnetic field. This can be understood from the dominant scale of thermal medium in the strong magnetic field, being the magnetic field, in the same way that the temperature dominates in a thermal medium in the absence of magnetic field. Thus although the presence of a strong magnetic field makes the pressure of hot QCD medium larger, the dependence of pressure on the temperature becomes less steep. Consistent with the above observations, the entropy density is found to decrease with the temperature in the presence of a strong magnetic field which is again consistent with the fact that the strong magnetic field restricts the dynamics of quarks to two dimensions, hence the phase space becomes squeezed resulting in the reduction of number of microstates. Moreover the energy density is seen to decrease and the speed of sound of thermal QCD medium increases in the presence of a strong magnetic field. These findings could have phenomenological implications in heavy ion collisions because the expansion dynamics of the medium produced in non-central ultra-relativistic heavy ion collisions is effectively controlled by both the energy density and the speed of sound.

  16. Strongly Coupled Magnetic and Electronic Transitions in Multivalent Strontium Cobaltites

    OpenAIRE

    Lee, J. H.; Choi, Woo Seok; Jeen, H.; Lee, H.-J.; Seo, J. H.; Nam, J.; Yeom, M. S.; Lee, H. N.

    2017-01-01

    The topotactic phase transition in SrCoO x (x = 2.5–3.0) makes it possible to reversibly transit between the two distinct phases, i.e. the brownmillerite SrCoO2.5 that is a room-temperature antiferromagnetic insulator (AFM-I) and the perovskite SrCoO3 that is a ferromagnetic metal (FM-M), owing to their multiple valence states. For the intermediate x values, the two distinct phases are expected to strongly compete with each other. With oxidation of SrCoO2.5, however, it has been conjectured t...

  17. Theory of the negative magnetoresistance in magnetic metallic multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Hood, R.Q.; Falicov, L.M. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1993-04-01

    The Boltzman equation is solved for a system consisting of alternating ferromagnetic normal metallic layers. The in-plane conductance of the film is calculated for two configurations: successive ferromagnetic layers aligned parallel and antiparallel to each other. Results explain the giant negative magnetoresistance encountered in these systems when an initial antiparallel arrangement is changed into a parallel configuration by application of an extemal magnetic field. The calculation depends on geometric parameters (the thicknesses of the layers); intrinsic metal parameters (number of conduction electrons, magnetization and effective masses in the layers); bulk sample properties (conductivity relaxation times); and interface scattering properties (diffuse scattering versus potential scattering at the interfaces). It is found that a large negative magnetoresistance requires, in general, considerable asymmetry in the interface scattering for the two spin orienmtions. All qualitative features of the experiments are reproduced. Quantitative agreement can be achieved with sensible values of the parameters. The effect can be conceptually explained based on considerations of phase-space availability for an electron of a given spin orientation as it travels through the multilayer sample in the various configurations and traverses the interfaces.

  18. Pion Production from Proton Synchrotron Radiation under Strong Magnetic Field in a Relativistic Quantum Approach

    Directory of Open Access Journals (Sweden)

    Maruyama Tomoyuki

    2016-01-01

    Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum approach do not agree with those obtained in the semi-classical approach. Then, we find that the anomalous magnetic moment of the proton greatly enhances the production rate by about two orders magnitude, and that the decay width satisfies a robust scaling law.

  19. Pion Production from Proton Synchrotron Radiation under Strong Magnetic Field in Relativistic Quantum Approach

    Directory of Open Access Journals (Sweden)

    Maruyama Tomoyuki

    2016-01-01

    Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum-field approach do not agree with those obtained in the semi-classical approach. Furthermore, we also find that the anomalous magnetic moment of the proton greatly enhances the production rate about by two orders of magnitude, and that the polar angle of an emitted pion is the same as that of an initial proton.

  20. Imaginary potential in strongly coupled N = 4 SYM plasma in a magnetic field

    Science.gov (United States)

    Zhang, Zi-qiang; Hou, De-fu

    2018-03-01

    We study the effect of a constant magnetic field on the imaginary part of a quarkonia potential in a strongly-coupled N = 4 SYM plasma. We consider the pair axis to be aligned perpendicularly and parallel to the magnetic field, respectively. For both cases, we find that the presence of the magnetic field tends to enhance the imaginary potential thus decreasing the thermal width. In addition, the magnetic field has a stronger effect on the imaginary potential when the pair axis is perpendicular to the magnetic field rather than parallel.

  1. Experimental demonstration of the equivalence of inductive and strongly coupled magnetic resonance wireless power transfer

    Science.gov (United States)

    Ricketts, David S.; Chabalko, Matthew J.; Hillenius, Andrew

    2013-02-01

    In this work, we show experimentally that wireless power transfer (WPT) using strongly coupled magnetic resonance (SCMR) and traditional induction are equivalent. We demonstrate that for a given coil separation, and to within 4%, strongly coupled magnetic resonance and traditional induction produce the same theoretical efficiency of wireless power transfer versus distance. Moreover, we show that the difference between traditional induction and strongly coupled magnetic resonance is in the implementation of the impedance matching network where strongly coupled magnetic resonance uses the mini-loop impedance match. The mini-loop impedance mach provides a low-loss, high-ratio impedance transformation that makes it desirable for longer distance wireless power transfer, where large impedance transformations are needed to maximize power transfer.

  2. Regularity and Chaos in the Hydrogen Atom Highly Excited with a Strong Magnetic Field

    Directory of Open Access Journals (Sweden)

    M. Amdouni

    2014-01-01

    Full Text Available The effects of the relativistic corrections on the energy spectra are analyzed. Effective simulations based on manipulations of operators in the Sturmian basis are developed. Discrete and continuous energy spectra of a hydrogen atom with realistic nucleus mass in a strong magnetic field are computed. The transition from regularity to chaos in diamagnetic problem with the effect of the nucleus recoil energy is explored. Anticrossing of energy levels is observed for strong magnetic field.

  3. Direct URCA-processes in neutron star quark core with strong magnetic field.

    Directory of Open Access Journals (Sweden)

    Belyaev Vasily

    2017-01-01

    In evaluations, the strength of magnetic field corresponds to the case, where the quarks of medium occupy a lot of Landau levels, while the electrons are in ground Landau level. The analytical dependence of neutrino emissivity on chemical potentials of quarks and electrons, temperature and magnetic field strength is obtained and briefly discussed. The result could be important in application to a massive strongly magnetized neutron star with quark core.

  4. Working with MRI: An investigation of occupational exposure to strong static magnetic fields and associated symptoms

    NARCIS (Netherlands)

    Schaap, K.

    2015-01-01

    Magnetic resonance imaging (MRI) makes use of electromagnetic fields in the non-ionizing radiation frequency ranges. One of them is a continuously present strong static magnetic field (SMF), which extends up to several meters around the scanner. Each time an MRI worker performs tasks near the

  5. THE EXTRAORDINARY COMPLEX MAGNETIC FIELD OF THE HELIUM-STRONG STAR HD 37776

    International Nuclear Information System (INIS)

    Kochukhov, Oleg; Lundin, Andreas; Romanyuk, Iosif; Kudryavtsev, Dmitry

    2011-01-01

    The early-type chemically peculiar stars often show strong magnetic fields on their surfaces. These magnetic topologies are organized on large scales and are believed to be close to an oblique dipole for most of the stars. In a striking exception to this general trend, the helium-strong star HD 37776 shows an extraordinary double-wave rotational modulation of the longitudinal magnetic field measurements, indicating a topologically complex and, possibly, record-strong magnetic field. Here we present a new investigation of the magnetic field structure of HD 37776, using both simple geometrical interpretation of the longitudinal field curve and detailed modeling of the time-resolved circular polarization line profiles with the help of a magnetic Doppler imaging technique. We derive a model of the magnetic field structure of HD 37776, which reconciles for the first time all magnetic observations available for this star. We find that the local surface field strength does not exceed ∼30 kG, while the overall field topology of HD 37776 is dominated by a non-axisymmetric component and represents by far the most complex magnetic field configuration found among early-type stars.

  6. Buoyant convection during Czochralski silicon growth with a strong, non-uniform, axisymmetric magnetic field

    Science.gov (United States)

    Khine, Y. Y.; Walker, J. S.

    1995-02-01

    This paper treats the buoyant convection during the Czochralski growth of silicon crystals with a steady, strong, non-uniform, axisymmetric magnetic field. We consider a family of magnetic fields which includes a uniform axial magnetic field and a "cusp" field which is produced by identical solenoids placed symmetrically above and below the plane of the crystal-melt interface and free surface. We investigate the evolution of the buoyant convection as the magnetic field is changed continuously from a uniform axial field to a cusp field, with a constant value of the root-mean-squared magnetic flux density in the melt. We also investigate changes as the magnetic flux density is increased. While the cusp field appears very promising, perfect alignment between the local magnetic field vector and the crystal-melt interface or free surface is not possible, so the effects of a slight misalignment are also investigated.

  7. Abnormally big magnetic resistance in a strongly compensated silicon doped with manganese

    International Nuclear Information System (INIS)

    Sadullaev, A.B.

    2004-01-01

    The work is devoted to study of an influence of compensating impurities electro-active atoms concentration on galvanomagnetic properties of strongly compensated silicon doped with manganese. It was shown, the possibility for magnetic resistance control of the strongly compensated Si samples by manganese electro-active impurity atoms concentration regulation

  8. Light bending by nonlinear electrodynamics under strong electric and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Young; Lee, Taekoon, E-mail: jykim@kunsan.ac.kr, E-mail: tlee@kunsan.ac.kr [Department of Physics, Kunsan National University, Daihakro 558, Kunsan 573-701 (Korea, Republic of)

    2011-11-01

    We calculate the bending angles of light under the strong electric and magnetic fields by a charged black hole and a magnetized neutron star according to the nonlinear electrodynamics of Euler-Heisenberg interaction. The bending angle of light by the electric field of charged black hole is computed from geometric optics and a general formula is derived for light bending valid for any orientation of the magnetic dipole. The astronomical significance of the light bending by magnetic field of a neutron star is discussed.

  9. Investigating short-range magnetism in strongly correlated materials via magnetic pair distribution function analysis and ab initio theory

    Science.gov (United States)

    Frandsen, Benjamin; Page, Katharine; Brunelli, Michela; Staunton, Julie; Billinge, Simon

    Short-range magnetic correlations are known to exist in a variety of strongly correlated electron systems, but our understanding of the role they play is challenged by the difficulty of experimentally probing such correlations. Magnetic pair distribution function (mPDF) analysis is a newly developed neutron total scattering method that can reveal short-range magnetic correlations directly in real space, and may therefore help ameliorate this difficulty. We present temperature-dependent mPDF measurements of the short-range magnetic correlations in the paramagnetic phase of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. We observe significant correlations on a ~1 nm length scale that differ substantially from the low-temperature long-range-ordered spin arrangement. With no free parameters, ab initio calculations using the self-interaction-corrected local spin density approximation of density functional theory quantitatively reproduce the magnetic correlations to a high degree of accuracy. These results yield valuable insight into the magnetic exchange in MnO and showcase the utility of the mPDF technique for studying magnetic properties of strongly correlated electron systems.

  10. Do strong, static magnetic fields act on living beings and chemical reactions

    International Nuclear Information System (INIS)

    Demmer, W.

    1986-01-01

    In general, magnetic fields are said to have no direct influence on living beings or simple chemical reactions. There is, however, evidence to confirm that changes in the earth's magnetic field or of artificially produced magnetic fields can alter the activity of different neuronal enzyme systems. An effect on the synthesis of β-galactosidase in the bacterium Escherichia coli by a feeble magnetic field (0.2 to 0.8 mT) and disturbances of the embryogenesis of frogs by a strong magnetic field (1.0 T) have been described. These and similar investigations with whole cells raise the question as to what the effect of magnetic fields on isolated and purified enzymes will be. (orig./SHA) [de

  11. Monte Carlo solutions of Schroedinger's equation for H2+ ion in strong magnetic fields

    International Nuclear Information System (INIS)

    Ozaki, Jiro; Tomishima, Yasuo

    1980-01-01

    The analytical expressions suitable for the Monte Carlo calculation to obtain the solution of Schroedinger's equation of hydrogen molecular ion in a strong magnetic field are derived. The wave functions, the energy values and the equilibrium internuclear distances of 1σsub(g) state of H 2 + are obtained numerically through the Monte Carlo simulation and compared with other results based on the variational method. The agreement between them is fairly good over a wide range of magnetic field. The calculation of the energy values of 1πsub(g) state of H 2 + for various internuclear distances taking a constant magnetic field as a parameter, shows that the antibonding 1πsub(g) state in the absence of the external magnetic field changes to a bonding state with an increasing magnetic field. The lowest energy values and the equilibrium internuclear distances of 1πsub(g) state are also calculated for various magnetic field. (author)

  12. Anisotropic shear viscosity of a strongly coupled non-Abelian plasma from magnetic branes

    Science.gov (United States)

    Critelli, R.; Finazzo, S. I.; Zaniboni, M.; Noronha, J.

    2014-09-01

    Recent estimates for the electromagnetic fields produced in the early stages of noncentral ultrarelativistic heavy ion collisions indicate the presence of magnetic fields B ˜O(0.1-15mπ2), where mπ is the pion mass. It is then of special interest to study the effects of strong (Abelian) magnetic fields on the transport coefficients of strongly coupled non-Abelian plasmas, such as the quark-gluon plasma formed in heavy ion collisions. In this paper we study the anisotropy in the shear viscosity induced by an external magnetic field in a strongly coupled N =4 super Yang-Mills (SYM) plasma. Due to the spatial anisotropy created by the magnetic field, the most general viscosity tensor of a magnetized plasma has five shear viscosity coefficients and two bulk viscosities. We use the holographic correspondence to evaluate two of the shear viscosities, η⊥≡ηxyxy (perpendicular to the magnetic field) and η∥≡ηxzxz=ηyzyz (parallel to the field). When B ≠0 the shear viscosity perpendicular to the field saturates the viscosity bound η⊥/s=1/(4π), while in the direction parallel to the field the bound is violated since η∥/s<1/(4π). However, the violation of the bound in the case of strongly coupled SYM is minimal even for the largest value of B that can be reached in heavy ion collisions.

  13. In-medium covariant propagator of baryons under a strong magnetic field: Effect of the intrinsic magnetic moments

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, R.M.; Paoli, A.L. de [Universidad Nacional de La Plata, and IFLP, Departamento de Fisica, Facultad de Ciencias Exactas, La Plata (Argentina)

    2016-11-15

    We obtain the covariant propagator at finite temperature for interacting baryons immersed in a strong magnetic field. The effect of the intrinsic magnetic moments on the Green function are fully taken into account. We make an expansion in terms of eigenfunctions of a Dirac field, which leads us to a compact form of its propagator. We present some simple applications of these propagators, where the statistical averages of nuclear currents and energy density are evaluated. (orig.)

  14. Strong magnetic enhancement in self-assembled multiferroic-ferrimagnetic nanostructures

    Science.gov (United States)

    Chen, Ying-Jiun; Hsieh, Ying-Hui; Liao, Sheng-Chieh; Hu, Zhiwei; Huang, Meng-Jie; Kuo, Wei-Cheng; Chin, Yi-Ying; Uen, Tzeng-Ming; Juang, Jenh-Yih; Lai, Chih-Huang; Lin, Hong-Ji; Chen, Chien-Te; Chu, Ying-Hao

    2013-05-01

    In the past decade, self-assembled vertical nano-heterostructures have drawn considerable attention because a high interface-to-volume ratio can be used to tailor or create functionalities. We have systematically investigated the magnetic properties of oxide heterostructures consisting of the CoFe2O4 nanopillars embedded in the BiFeO3 matrix using macroscopic magnetization measurements and element-selective soft X-ray absorption magnetic circular dichroism (XMCD) at the Co- and Fe-L2,3 edge. The magnetization and XMCD data show that the total ordered magnetic moment of Co2+ in CoFe2O4-BiFeO3 nano-heterostructures is strongly enhanced. This study clearly indicates that the high interface-to-volume ratio vertical nanostructure creates a strong ferromagnetic and antiferromagnetic magnetic coupling via an interface. Furthermore, the magnetic coupling can be tuned in the multiferroic-ferrimagnetic self-assembled heterostructures by controlling the spacing between nanopillars.In the past decade, self-assembled vertical nano-heterostructures have drawn considerable attention because a high interface-to-volume ratio can be used to tailor or create functionalities. We have systematically investigated the magnetic properties of oxide heterostructures consisting of the CoFe2O4 nanopillars embedded in the BiFeO3 matrix using macroscopic magnetization measurements and element-selective soft X-ray absorption magnetic circular dichroism (XMCD) at the Co- and Fe-L2,3 edge. The magnetization and XMCD data show that the total ordered magnetic moment of Co2+ in CoFe2O4-BiFeO3 nano-heterostructures is strongly enhanced. This study clearly indicates that the high interface-to-volume ratio vertical nanostructure creates a strong ferromagnetic and antiferromagnetic magnetic coupling via an interface. Furthermore, the magnetic coupling can be tuned in the multiferroic-ferrimagnetic self-assembled heterostructures by controlling the spacing between nanopillars. Electronic supplementary

  15. Heavy quark potential in a static and strong homogeneous magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Mujeeb; Chatterjee, Bhaswar; Patra, Binoy Krishna [Indian Institute of Technology Roorkee, Department of Physics, Roorkee (India)

    2017-11-15

    We have investigated the properties of quarkonia in a thermal QCD medium in the background of strong magnetic field. For that purpose, we employ the Schwinger proper-time quark propagator in the lowest Landau level to calculate the one-loop gluon self-energy, which in the sequel gives the effective gluon propagator. As an artifact of strong magnetic field approximation (eB >> T{sup 2} and eB >> m{sup 2}), the Debye mass for massless flavors is found to depend only on the magnetic field which is the dominant scale in comparison to the scales prevalent in the thermal medium. However, for physical quark masses, it depends on both magnetic field and temperature in a low temperature and high magnetic field but the temperature dependence is very meager and becomes independent of the temperature beyond a certain temperature and magnetic field. With the above mentioned ingredients, the potential between heavy quark (Q) and anti-quark (anti Q) is obtained in a hot QCD medium in the presence of a strong magnetic field by correcting both short- and long-range components of the potential in the real-time formalism. It is found that the long-range part of the quarkonium potential is affected much more by magnetic field as compared to the short-range part. This observation facilitates us to estimate the magnetic field beyond which the potential will be too weak to bind Q anti Q together. For example, the J/ψ is dissociated at eB ∝ 10 m{sub π}{sup 2} and Υ is dissociated at eB ∝ 100 m{sub π}{sup 2} whereas its excited states, ψ{sup '} and Υ{sup '} are dissociated at smaller magnetic field eB = m{sub π}{sup 2}, 13 m{sub π}{sup 2}, respectively. (orig.)

  16. Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum

    Science.gov (United States)

    Fujiwara, Yoshihisa; Tomishige, Masahiko; Itoh, Yasuhiro; Fujiwara, Masao; Shibata, Naho; Kosaka, Toshikazu; Hosoya, Hiroshi; Tanimoto, Yoshifumi

    2006-05-01

    Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum was studied by using a superconducting magnet. Around a centre of a round vessel, random swimming at 0 T and aligned swimming parallel to the magnetic field (MF) of 8 T were observed. Near a wall of the vessel, however, swimming round and round along the wall at 0 T and aligned swimming of turning at right angles upon collision with the wall, which was remarkable around 1-4 T, were detected. It was experimentally revealed that the former MF-induced parallel swimming at the vessel centre was caused physicochemically by the parallel magnetic orientation of the cell itself. From magnetic field dependence of the extent of the orientation, the magnetic susceptibility anisotropy (χ ∥-χ ⊥) was first obtained to be 3.4× 10-23 emu cell-1 at 298 K for Paramecium caudatum. The orientation of the cell was considered to result from the magnetic orientation of the cell membrane. On the other hand, although mechanisms of the latter swimming near the vessel wall regardless of the absence and presence of the magnetic field are unclear at present, these experimental results indicate that whether the cell exists near the wall alters the magnetic field effect on the swimming in the horizontal magnetic field.

  17. One-electron atomic-molecular ions containing lithium in a strong magnetic field

    International Nuclear Information System (INIS)

    Olivares-Pilon, H; Turbiner, A V; Vieyra, J C Lopez; Baye, D

    2010-01-01

    The one-electron lithium-containing Coulomb systems of atomic type Li 2+ and molecular type Li 5+ 2 , LiHe 4+ and LiH 3+ are studied in the presence of a strong magnetic field B ≤ 10 7 au in a non-relativistic framework. They are considered at the Born-Oppenheimer approximation of zero order (infinitely massive centres) within the parallel configuration (molecular axis parallel to the magnetic field). The variational and Lagrange-mesh methods are employed, complementing each other. It is demonstrated that the molecular systems LiH 3+ , LiHe 4+ and Li 5+ 2 can exist for sufficiently strong magnetic fields B ∼> 10 4 au and that Li 5+ 2 can even be stable at magnetic fields typical of magnetars.

  18. Viscosity of two-dimensional strongly coupled dusty plasma modified by a perpendicular magnetic field.

    Science.gov (United States)

    Feng, Yan; Lin, Wei; Murillo, M S

    2017-11-01

    Transport properties of two-dimensional (2D) strongly coupled dusty plasmas have been investigated in detail, but never for viscosity with a strong perpendicular magnetic field; here, we examine this scenario using Langevin dynamics simulations of 2D liquids with a binary Yukawa interparticle interaction. The shear viscosity η of 2D liquid dusty plasma is estimated from the simulation data using the Green-Kubo relation, which is the integration of the shear stress autocorrelation function. It is found that, when a perpendicular magnetic field is applied, the shear viscosity of 2D liquid dusty plasma is modified substantially. When the magnetic field is increased, its viscosity increases at low temperatures, while at high temperatures its viscosity diminishes. It is determined that these different variational trends of η arise from the different behaviors of the kinetic and potential parts of the shear stress under external magnetic fields.

  19. The thermodynamic spin magnetization of strongly correlated 2d electrons in a silicon inversion layer

    OpenAIRE

    Prus, O.; Yaish, Y.; Reznikov, M.; Sivan, U.; Pudalov, V.

    2002-01-01

    A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied to electrons in a silicon inversion layer. Interplay between the ferromagnetic interaction and disorder enhances the low temperature susceptibility up to 7.5 folds compared with the Pauli susceptibility of non-interacting electrons. The magnetization peaks in the vicinity of the density where transition to strong localization takes place. At the same density, the suscep...

  20. Axion production from Landau quantization in the strong magnetic field of magnetars

    Science.gov (United States)

    Maruyama, Tomoyuki; Balantekin, A. Baha; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.

    2018-04-01

    We utilize an exact quantum calculation to explore axion emission from electrons and protons in the presence of the strong magnetic field of magnetars. The axion is emitted via transitions between the Landau levels generated by the strong magnetic field. The luminosity of axions emitted by protons is shown to be much larger than that of electrons and becomes stronger with increasing matter density. Cooling by axion emission is shown to be much larger than neutrino cooling by the Urca processes. Consequently, axion emission in the crust may significantly contribute to the cooling of magnetars. In the high-density core, however, it may cause heating of the magnetar.

  1. Chiral soliton lattice and charged pion condensation in strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, Tomáš [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Yamamoto, Naoki [Department of Physics, Keio University,Yokohama 223-8522 (Japan)

    2017-04-21

    The Chiral Soliton Lattice (CSL) is a state with a periodic array of topological solitons that spontaneously breaks parity and translational symmetries. Such a state is known to appear in chiral magnets. We show that CSL also appears as a ground state of quantum chromodynamics at nonzero chemical potential in a magnetic field. By analyzing the fluctuations of the CSL, we furthermore demonstrate that in strong but achievable magnetic fields, charged pions undergo Bose-Einstein condensation. Our results, based on a systematic low-energy effective theory, are model-independent and fully analytic.

  2. Off-specular polarized neutron reflectometry study of magnetic dots with a strong shape anisotropy

    CERN Document Server

    Temst, K; Moshchalkov, V V; Bruynseraede, Y; Fritzsche, H; Jonckheere, R

    2002-01-01

    We have measured the off-specular polarized neutron reflectivity of a regular array of rectangular magnetic polycrystalline Co dots, which were prepared by a combination of electron-beam lithography, molecular beam deposition, and lift-off processes. The dots have a length-to-width ratio of 4:1 imposing a strong shape anisotropy. The intensity of the off-specular satellite reflection was monitored as a function of the magnetic field applied parallel to the rows of dots and in the plane of the sample, allowing us to analyze the magnetization-reversal process using the four spin-polarized cross sections. (orig.)

  3. Study of Strong Magnetic Fields Using Parametric Instability in a Magnetised Plasma

    Science.gov (United States)

    Ivanov, V. V.; Maximov, A. V.; Anderson, A. A.; Bauer, B. S.; Yates, K.

    2014-10-01

    Generation of strong magnetic fields with a strength of 10--50 MG plays a key role in some recent conceptions for controlled fusion. We suggest a laser method for measuring the local magnetic field, B > 10 MG, based on the parametric decay of the laser radiation to ω/2 and 3/2 ω harmonics which are generated in the area with the electron density of a quarter of the critical plasma density. Spectral components of parametric harmonics carry a signature of both the plasma temperature and strong magnetic field. A two-plasmon decay of laser radiation was studied in a magnetized plasma at the 1 MA pulsed power Zebra facility at the University of Nevada, Reno. Dense magnetized plasma with a magnetic field of 1--3 MG was created by the 1MA current flowing in the metal rod 0.7--2 mm in diameter. Radiation from the narrowband laser with intensity >1014 W/cm2 was focused on the surface plasma. Spectrum of the backscattering 3/2 ω harmonic included ``red'' and ``blue'' shifted components. Large 2-3 nm shifts of spectral components was identified with laser heating of plasma. Components with a small 0.1 nm spectral shift of may be linked to the magnetic field. Work was supported by the DOE Grant DE-SC0008824 and DOE/NNSA UNR Grant DE-FC52-06NA27616.

  4. The determination of the rotation period and magnetic field geometry of the strongly magnetic roAp star HD 154708

    NARCIS (Netherlands)

    Hubrig, S.; Mathys, G.; Kurtz, D.W.; Schöller, M.; Elkin, V.G.; Henrichs, H.F.

    2009-01-01

    We obtained 13 spectropolarimetric observations of the strongly magnetic rapidly oscillating Ap star HD 154708 over 3 months with the multimode instrument FORS 1, installed at the 8-m Kueyen telescope of the Very Large Telescope. These observations have been used for the determination of the

  5. Description of the magnetic properties of strongly correlated disordered solid solutions in the coherent potential approximation

    Science.gov (United States)

    Korotin, M. A.; Skorikov, N. A.

    2015-06-01

    A method for electronic structure calculations of strongly correlated materials based on the coherent potential approximation is formulated and implemented. Method is applied for investigation of the electronic structure and local magnetic moments of the strongly correlated systems with d- and f-electrons: NiO-ZnO solid solution, nonstoichiometric perovskite LaMnO3-x, doped compound TiO2:Fe, and rare-earth transition-metal intermetallic compound GdNi2:Mn.

  6. Luminosity and cooling of highly magnetized white dwarfs: suppression of luminosity by strong magnetic fields

    Science.gov (United States)

    Bhattacharya, Mukul; Mukhopadhyay, Banibrata; Mukerjee, Subroto

    2018-03-01

    We investigate the luminosity and cooling of highly magnetized white dwarfs with electron-degenerate cores and non-degenerate surface layers where cooling occurs by diffusion of photons. We find the temperature and density profiles in the surface layers or envelope of white dwarfs by solving the magnetostatic equilibrium and photon diffusion equations in a Newtonian framework. We also obtain the properties of white dwarfs at the core-envelope interface, when the core is assumed to be practically isothermal. With the increase in magnetic field, the interface temperature increases whereas the interface radius decreases. For a given age of the white dwarf and for fixed interface radius or interface temperature, we find that the luminosity decreases significantly from about 10-6 L⊙ to 10-9 L⊙ as the magnetic field strength increases from about 109 G to 1012 G at the interface and hence the envelope. This is remarkable because it argues that magnetized white dwarfs are fainter and can be practically hidden in an observed H-R diagram. We also find the cooling rates corresponding to these luminosities. Interestingly, the decrease in temperature with time, for the fields under consideration, is not found to be appreciable.

  7. Stability of matrices with sufficiently strong negative-dominant-diagonal submatrices

    NARCIS (Netherlands)

    Nieuwenhuis, H.J.; Schoonbeek, L.

    A well-known sufficient condition for stability of a system of linear first-order differential equations is that the matrix of the homogeneous dynamics has a negative dominant diagonal. However, this condition cannot be applied to systems of second-order differential equations. In this paper we

  8. Critical point in the QCD phase diagram for extremely strong background magnetic fields

    International Nuclear Information System (INIS)

    Endrödi, Gergely

    2015-01-01

    Lattice simulations have demonstrated that a background (electro)magnetic field reduces the chiral/deconfinement transition temperature of quantum chromodynamics for eB<1 GeV 2 . On the level of observables, this reduction manifests itself in an enhancement of the Polyakov loop and in a suppression of the light quark condensates (inverse magnetic catalysis) in the transition region. In this paper, we report on lattice simulations of 1+1+1-flavor QCD at an unprecedentedly high value of the magnetic field eB=3.25 GeV 2 . Based on the behavior of various observables, it is shown that even at this extremely strong field, inverse magnetic catalysis prevails and the transition, albeit becoming sharper, remains an analytic crossover. In addition, we develop an algorithm to directly simulate the asymptotically strong magnetic field limit of QCD. We find strong evidence for a first-order deconfinement phase transition in this limiting theory, implying the presence of a critical point in the QCD phase diagram. Based on the available lattice data, we estimate the location of the critical point.

  9. Consequence of total lepton number violation in strongly magnetized iron white dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Belyaev, V.B. [Bogolyubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Ricci, P. [Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, I-50019 Sesto Fiorentino (Firenze) (Italy); Šimkovic, F. [Department of Nuclear Physics and Biophysics, Comenius University, Mlynská dolina F1, SK-842 15, Bratislava (Slovakia); Bogolyubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Adam, J.; Tater, M. [Institute of Nuclear Physics ASCR, CZ-250 68 Řež (Czech Republic); Truhlík, E., E-mail: truhlik@ujf.cas.cz [Institute of Nuclear Physics ASCR, CZ-250 68 Řež (Czech Republic)

    2015-05-15

    The influence of a neutrinoless electron to positron conversion on a cooling of strongly magnetized iron white dwarfs is studied. It is shown that they can be good candidates for soft gamma-ray repeaters and anomalous X-ray pulsars.

  10. Numerical analysis of blood flow in realistic arteries subjected to strong non-uniform magnetic fields

    NARCIS (Netherlands)

    Kenjeres, S.

    2008-01-01

    The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier–Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell’s equations

  11. Quantum magnetism in strongly interacting one-dimensional spinor Bose systems

    DEFF Research Database (Denmark)

    Salami Dehkharghani, Amin; Volosniev, A. G.; Lindgren, E. J.

    2015-01-01

    -range inter-species interactions much larger than their intra-species interactions and show that they have novel energetic and magnetic properties. In the strongly interacting regime, these systems have energies that are fractions of the basic harmonic oscillator trap quantum and have spatially separated...

  12. Study of rare earth local moment magnetism and strongly correlated phenomena in various crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Tai [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    Benefiting from unique properties of 4f electrons, rare earth based compounds are known for offering a versatile playground for condensed matter physics research as well as industrial applications. This thesis focuses on three specific examples that further explore the rare earth local moment magnetism and strongly correlated phenomena in various crystal structures.

  13. Equation of state of strange quark matter in a strong magnetic field

    International Nuclear Information System (INIS)

    Isayev, A.A.; Yang, J.

    2012-01-01

    Thermodynamic properties of strange quark matter (SQM) in strong magnetic fields H up to 10 20 G are considered at zero temperature within the MIT bag model. The effects of the pressure anisotropy, exhibiting in the difference between the pressures along and perpendicular to the field direction, become essential at H>H t h , with the estimate 10 17 t h 18 G. The longitudinal pressure vanishes in the critical field H c , which can be somewhat less or larger than 10 18 G, depending on the total baryon number density and bag pressure. As a result, the longitudinal instability occurs in strongly magnetized SQM. The appearance of such instability sets the upper bound on the magnetic field strength which can be reached in the interior of a neutron star with the quark core. The longitudinal and transverse pressures as well as the anisotropic equation of state of SQM are determined under the conditions relevant for the cores of magnetars

  14. Probing spin correlations with phonons in the strongly frustrated magnet ZnCr2O4.

    Science.gov (United States)

    Sushkov, A B; Tchernyshyov, O; Ratcliff, W; Cheong, S W; Drew, H D

    2005-04-08

    The spin-lattice coupling plays an important role in strongly frustrated magnets. In ZnCr2O4, an excellent realization of the Heisenberg antiferromagnet on the pyrochlore network, a lattice distortion relieves the geometrical frustration through a spin-Peierls-like phase transition at T(c)=12.5 K. Conversely, spin correlations strongly influence the elastic properties of a frustrated magnet. By using infrared spectroscopy and published data on magnetic specific heat, we demonstrate that the frequency of an optical phonon triplet in ZnCr2O4 tracks the nearest-neighbor spin correlations above T(c). The splitting of the phonon triplet below T(c) provides a way to measure the spin-Peierls order parameter.

  15. Spin polarization in high density quark matter under a strong external magnetic field

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; Da Providência, João; Providência, Constança

    2016-01-01

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor-type interact......In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor...... phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs....

  16. Optical investigation of the strong spin-orbit-coupled magnetic semimetal YbMnBi2

    Science.gov (United States)

    Chaudhuri, Dipanjan; Cheng, Bing; Yaresko, Alexander; Gibson, Quinn D.; Cava, R. J.; Armitage, N. P.

    2017-08-01

    Strong spin-orbit coupling (SOC) can result in ground states with nontrivial topological properties. The situation is even richer in magnetic systems where the magnetic ordering can potentially have strong influence over the electronic band structure. The class of A MnBi2 (A = Sr, Ca) compounds are important in this context as they are known to host massive Dirac fermions with strongly anisotropic dispersion, which is believed to be due to the interplay between strong SOC and magnetic degrees of freedom. We report the optical conductivity of YbMnBi2, a newly discovered member of this family and a proposed Weyl semimetal (WSM) candidate with broken time reversal symmetry. Together with density functional theory (DFT) band-structure calculations, we show that the complex conductivity can be interpreted as the sum of an intraband Drude response and interband transitions. We argue that the canting of the magnetic moments that has been proposed to be essential for the realization of the WSM in an otherwise antiferromagnetically ordered system is not necessary to explain the optical conductivity. We believe our data is explained qualitatively by the uncanted magnetic structure with a small offset of the chemical potential from strict stochiometry. We find no definitive evidence of a bulk Weyl nodes. Instead, we see signatures of a gapped Dirac dispersion, common in other members of A MnBi2 family or compounds with similar 2D network of Bi atoms. We speculate that the evidence for a WSM seen in ARPES arises through a surface magnetic phase. Such an assumption reconciles all known experimental data.

  17. First Detection of a Strong Magnetic Field on a Bursty Brown Dwarf: Puzzle Solved

    Science.gov (United States)

    Berdyugina, S. V.; Harrington, D. M.; Kuzmychov, O.; Kuhn, J. R.; Hallinan, G.; Kowalski, A. F.; Hawley, S. L.

    2017-09-01

    We report the first direct detection of a strong, 5 kG magnetic field on the surface of an active brown dwarf. LSR J1835+3259 is an M8.5 dwarf exhibiting transient radio and optical emission bursts modulated by fast rotation. We have detected the surface magnetic field as circularly polarized signatures in the 819 nm sodium lines when an active emission region faced the Earth. Modeling Stokes profiles of these lines reveals the effective temperature of 2800 K and log gravity acceleration of 4.5. These parameters place LSR J1835+3259 on evolutionary tracks as a young brown dwarf with the mass of 55+/- 4{M}{{J}} and age of 22 ± 4 Myr. Its magnetic field is at least 5.1 kG and covers at least 11% of the visible hemisphere. The active region topology recovered using line profile inversions comprises hot plasma loops with a vertical stratification of optical and radio emission sources. These loops rotate with the dwarf in and out of view causing periodic emission bursts. The magnetic field is detected at the base of the loops. This is the first time that we can quantitatively associate brown dwarf non-thermal bursts with a strong, 5 kG surface magnetic field and solve the puzzle of their driving mechanism. This is also the coolest known dwarf with such a strong surface magnetic field. The young age of LSR J1835+3259 implies that it may still maintain a disk, which may facilitate bursts via magnetospheric accretion, like in higher-mass T Tau-type stars. Our results pave a path toward magnetic studies of brown dwarfs and hot Jupiters.

  18. Centrifugal pumping during Czochralski silicon growth with a strong, non-uniform, axisymmetric magnetic field

    Science.gov (United States)

    Khine, Y. Y.; Walker, J. S.

    1996-08-01

    Centrifugal pumping flows are produced in the melt by the rotations of crystal and crucible during the Czochralski growth of silicon crystals. This paper treats the centrifugal pumping effects with a steady, strong, non-uniform axisymmetric magnetic field. We consider a family of magnetic fields ranging from a uniform axial field to a "cusp" field, which has a purely radial field at the crystal-melt interface and free surface. We present the numerical solutions for the centrifugal pumping flows as the magnetic field is changed continuously from a uniform axial field to a cusp one, and for arbitrary Hartmann number. Since the perfect alignment between the local magnetic field vector and the crystal-melt interface or free surface is not likely, we also investigate the effects of a slight misalignment.

  19. Sound absorption in a field of a strong electromagnetic wave in a quantizied magnetic field

    International Nuclear Information System (INIS)

    Chajkovskij, I.A.

    1974-01-01

    A coefficient of sound absorption GAMMA in a semiconductor and semi-metal in the quantized magnetic field is calculated for a system exposed to a field of strong electromagnetic radiation. The cases E parallel H and E orthogonal H are considered. Along with the already known strong oscillations of sound absorption in magnetic fields, the absorption spectrum GAMMAsub(par) and GAMMAsub(orth) shows new oscillations representing a manifestation of the quasi-energetic electron spectrum in the field of a strong electromagnetic wave. The oscillation height at E parallel H is modulated by the electromagnetic field. It is shown that the ratio GAMMAsub(par)/GAMMAsub(orth) allows the determination of the effective mass of the carriers

  20. Phase manipulation of Goos–Hänchen shifts in a single-layer of graphene nanostructure under strong magnetic field

    Science.gov (United States)

    Solookinejad, Gh; Jabbari, M.; Panahi, M.; Ahmadi Sangachin, E.

    2017-11-01

    In this paper, we discuss the phase management of Goos–Hänchen (GH) shifts of a probe light through a cavity with a single-layer graphene nanostructure under a strong magnetic field. By using the quantum mechanical density matrix formalism we study the GH shifts of reflected and transmitted light beams. It is realized that negative or positive GH shifts can be achieved simultaneously by tuning some controllable parameters such as relative phase and the Rabi frequency of the applied fields. Moreover, the thickness effect of the cavity structure is considered as an effective parameter for adjusting the GH shifts of reflected and transmitted light beams. We find that by choosing suitable parameters, a maximum negative shift of 4.5 mm and positive shift of 5.4 mm are possible for GH shifts in reflected and transmitted light. Our proposed model may be useful for developing all-optical devices in the infrared region.

  1. Magnetic Fields in the Massive Dense Cores of the DR21 Filament: Weakly Magnetized Cores in a Strongly Magnetized Filament

    Energy Technology Data Exchange (ETDEWEB)

    Ching, Tao-Chung; Lai, Shih-Ping [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Zhang, Qizhou; Girart, Josep M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138 (United States); Qiu, Keping [School of Astronomy and Space Science, Nanjing University, 163 Xianlin Avenue, Nanjing 210023 (China); Liu, Hauyu B., E-mail: chingtaochung@gmail.com [European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)

    2017-04-01

    We present Submillimeter Array 880 μ m dust polarization observations of six massive dense cores in the DR21 filament. The dust polarization shows complex magnetic field structures in the massive dense cores with sizes of 0.1 pc, in contrast to the ordered magnetic fields of the parsec-scale filament. The major axes of the massive dense cores appear to be aligned either parallel or perpendicular to the magnetic fields of the filament, indicating that the parsec-scale magnetic fields play an important role in the formation of the massive dense cores. However, the correlation between the major axes of the cores and the magnetic fields of the cores is less significant, suggesting that during the core formation, the magnetic fields below 0.1 pc scales become less important than the magnetic fields above 0.1 pc scales in supporting a core against gravity. Our analysis of the angular dispersion functions of the observed polarization segments yields a plane-of-sky magnetic field strength of 0.4–1.7 mG for the massive dense cores. We estimate the kinematic, magnetic, and gravitational virial parameters of the filament and the cores. The virial parameters show that the gravitational energy in the filament dominates magnetic and kinematic energies, while the kinematic energy dominates in the cores. Our work suggests that although magnetic fields may play an important role in a collapsing filament, the kinematics arising from gravitational collapse must become more important than magnetic fields during the evolution from filaments to massive dense cores.

  2. ON MULTIPLE RECONNECTION X-LINES AND TRIPOLAR PERTURBATIONS OF STRONG GUIDE MAGNETIC FIELDS

    International Nuclear Information System (INIS)

    Eriksson, S.; Gosling, J. T.; Lapenta, G.; Newman, D. L.; Goldman, M. V.; Phan, T. D.; Lavraud, B.; Khotyaintsev, Yu. V.; Carr, C. M.; Markidis, S.

    2015-01-01

    We report new multi-spacecraft Cluster observations of tripolar guide magnetic field perturbations at a solar wind reconnection exhaust in the presence of a guide field B M   which is almost four times as strong as the reversing field B L . The novel tripolar field consists of two narrow regions of depressed B M , with an observed 7%–14% ΔB M magnitude relative to the external field, which are found adjacent to a wide region of enhanced B M within the exhaust. A stronger reversing field is associated with each B M depression. A kinetic reconnection simulation for realistic solar wind conditions and the observed strong guide field reveals that tripolar magnetic fields preferentially form across current sheets in the presence of multiple X-lines as magnetic islands approach one another and merge into fewer and larger islands. The simulated ΔB M /ΔX N over the normal width ΔX N between a B M minimum and the edge of the external region agree with the normalized values observed by Cluster. We propose that a tripolar guide field perturbation may be used to identify candidate regions containing multiple X-lines and interacting magnetic islands at individual solar wind current sheets with a strong guide field

  3. Bound-state β decay of a neutron in a strong magnetic field

    International Nuclear Information System (INIS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2005-01-01

    The β decay of a neutron into a bound (pe - ) state and an antineutrino in the presence of a strong uniform magnetic field (B > or approx. 10 13 G) is considered. The β decay process is treated within the framework of the standard model of weak interactions. A Bethe-Salpeter formalism is employed for description of the bound (pe - ) system in a strong magnetic field. For the field strengths 10 13 18 G the estimate for the ratio of the bound-state decay rate w b and the usual (continuum-state) decay rate w c is derived. It is found that in such strong magnetic fields w b /w c ∼0.1-0.4. This is in contrast to the field-free case, where w b /w c ≅4.2x10 -6 [J. N. Bahcall, Phys. Rev. 124, 495 (1961); L. L. Nemenov, Sov. J. Nucl. Phys. 15, 582 (1972); X. Song, J. Phys. G: Nucl. Phys. 13, 1023 (1987)]. The dependence of the ratio w b /w c on the magnetic field strength B exhibits a logarithmiclike behavior. The obtained results can be important for applications in astrophysics and cosmology

  4. Experimental study of transport of relativistic electron beams in strong magnetic mirror field

    Science.gov (United States)

    Sakata, Shohei; Kondo, Kotaro; Bailly-Grandvaux, Mathiu; Bellei, Claudio; Santos, Joao; Firex Project Team

    2015-11-01

    Relativistic electron beams REB produced by ultra high intense laser pulses have generally a large divergence angle that results in degradation of energy coupling between the REB and a fuel core in the fast ignition scheme. Guiding and focusing of the REB by a strong external magnetic field was proposed to achieve high efficiency. We investigated REB transport through 50 μm or 250 μm thick plastic foils CuI doped under external magnetic fields, in magnetic mirror configurations of 1.2 or 4 mirror ratio. The experiment was carried out at the GEKKO XII and LFEX laser facility. Spatial pattern of the REB was measured by coherent transition radiation and/or Cu Ka x ray emission from the rear surface of the foil targets. Strong collimation of the REB by the external magnetic field was observed with 50 μm thick plastic targets, while the REB scattered in 250 μm thick targets. The experimental results are compared with computer simulations to understand the physical mechanisms of the REB transport in the external magnetic field. This work is supported by NIFS (Japan), MEXT/JSPS KAKENHI (Japan), JSPS Fellowship (Japan), ANR (France) and COST (Europe).

  5. Quantum Femtosecond Magnetism: Phase Transition in Step with Light in a Strongly Correlated Manganese Oxide

    Science.gov (United States)

    Wang, Jigang

    2014-03-01

    Research of non-equilibrium phase transitions of strongly correlated electrons is built around addressing an outstanding challenge: how to achieve ultrafast manipulation of competing magnetic/electronic phases and reveal thermodynamically hidden orders at highly non-thermal, femtosecond timescales? Recently we reveal a new paradigm called quantum femtosecond magnetism-photoinduced femtosecond magnetic phase transitions driven by quantum spin flip fluctuations correlated with laser-excited inter-atomic coherent bonding. We demonstrate an antiferromagnetic (AFM) to ferromagnetic (FM) switching during about 100 fs laser pulses in a colossal magneto-resistive manganese oxide. Our results show a huge photoinduced femtosecond spin generation, measured by magnetic circular dichroism, with photo-excitation threshold behavior absent in the picosecond dynamics. This reveals an initial quantum coherent regime of magnetism, while the optical polarization/coherence still interacts with the spins to initiate local FM correlations that compete with the surrounding AFM matrix. Our results thus provide a framework that explores quantum non-equilibrium kinetics to drive phase transitions between exotic ground states in strongly correlated elecrons, and raise fundamental questions regarding some accepted rules, such as free energy and adiabatic potential surface. This work is in collaboration with Tianqi Li, Aaron Patz, Leonidas Mouchliadis, Jiaqiang Yan, Thomas A. Lograsso, Ilias E. Perakis. This work was supported by the National Science Foundation (contract no. DMR-1055352). Material synthesis at the Ames Laboratory was supported by the US Department of Energy-Basic Energy Sciences (contract no. DE-AC02-7CH11358).

  6. Linear theory of a cold relativistic beam in a strongly magnetized finite-geometry plasma

    International Nuclear Information System (INIS)

    Gagne, R.R.J.; Shoucri, M.M.

    1976-01-01

    The linear theory of a finite-geometry cold relativistic beam propagating in a cold homogeneous finite-geometry plasma, is investigated in the case of a strongly magnetized plasma. The beam is assumed to propagate parallel to the external magnetic field. It is shown that the instability which takes place at the Cherenkov resonance ωapprox. =k/subz/v/subb/ is of the convective type. The effect of the finite geometry on the instability growth rate is studied and is shown to decrease the growth rate, with respect to the infinite geometry, by a factor depending on the ratio of the beam-to-plasma radius

  7. Transport coefficients of InSb in a strong magnetic field

    International Nuclear Information System (INIS)

    Nakamura, Hiroaki; Ikeda, Kazuaki; Yamaguchi, Satarou

    1998-02-01

    Improvement of a superconducting magnet system makes induction of a strong magnetic field easier. This fact gives us a possibility of energy conversion by the Nernst effect. As the first step to study the Nernst element, we measured the conductivity, the Hall coefficient, the thermoelectric power and the Nernst coefficient of the InSb, which is one of candidates of the Nernst elements. From this experiment, it is concluded that the Nernst coefficient is smaller than the theoretical values. On the other hand, the conductivity, the Hall coefficient and the thermoelectric power has the values expected by the theory. (author)

  8. Magnetic and resonant X-ray scattering investigations of strongly correlated electron systems

    International Nuclear Information System (INIS)

    Paolasini, L.; Bergevin, F. de

    2008-01-01

    Resonant X-ray scattering is a method which combines high-Q resolution X-ray elastic diffraction and atomic core-hole spectroscopy for investigating electronic and magnetic long-range ordered structures in condensed matter. During recent years the development of theoretical models to describe resonant X-ray scattering amplitudes and the evolution of experimental techniques, which include the control and analysis of linear photon polarization and the introduction of extreme environment conditions such as low temperatures, high magnetic field and high pressures, have opened a new field of investigation in the domain of strongly correlated electron systems. (authors)

  9. Strong commitment to traditional Protestant religious beliefs is negatively related to beliefs in paranormal phenomena.

    Science.gov (United States)

    Hillstrom, E L; Strachan, M

    2000-02-01

    Numerous studies have yielded small, negative correlations between measures of paranormal and "traditional religious beliefs". This may partly reflect opinions of Christians in the samples who take biblical sanctions against many "paranormal" activities seriously. To test this, 391 college students (270 women and 121 men) rated their beliefs in various paranormal phenomena and were classified as Believers, Nominal Believers, and Nonbelievers on the strength of their self-rated commitment to key biblical (particularly Protestant) doctrines. As predicted, Believers were significantly less likely than Nominal Believers or Nonbelievers to endorse reincarnation, contact with the dead, UFOs, telepathy, prophecy, psychokinesis, or healing, while the beliefs of Nominal Believers were similar to those of Nonbelievers. Substantial percentages of Nominal and Nonbelievers (30-50%) indicated at least moderate acceptance of the paranormal phenomena surveyed.

  10. Drag force in strongly coupled { N }=4 supersymmetric Yang–Mills plasma in a magnetic field

    Science.gov (United States)

    Zhang, Zi-qiang; Ma, Ke; Hou, De-fu

    2018-02-01

    Applying AdS/CFT correspondence, we study the effect of a constant magnetic field { B } on the drag force associated with a heavy quark moving through a strongly-coupled { N }=4 supersymmetric Yang–Mills plasma. The quark is considered moving transverse and parallel to { B }. It is shown that for transverse case, the drag force is linearly dependent on { B } in all regions, while for parallel case, the drag force increases monotonously with increasing { B } and also reveals a linear behavior in the regions of strong { B }. In addition, we find that { B } has a more important effect in the transverse case than for the parallel.

  11. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    Science.gov (United States)

    Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  12. Ideal magnetohydrodynamic simulations of unmagnetized dense plasma jet injection into a hot strongly magnetized plasma

    OpenAIRE

    Liu, Wei; Hsu, Scott C.

    2010-01-01

    We present results from three-dimensional ideal magnetohydrodynamic simulations of unmagnetized dense plasma jet injection into a uniform hot strongly magnetized plasma, with the aim of providing insight into core fueling of a tokamak with parameters relevant for ITER and NSTX (National Spherical Torus Experiment). Unmagnetized dense plasma jet injection is similar to compact toroid injection but with much higher plasma density and total mass, and consequently lower required injection velocit...

  13. Limiting and Fedosov's Currents of a Strongly Magnetized Electron Beam in Asymmetric Transportation Channels

    Science.gov (United States)

    Goikhman, M. B.; Gromov, A. V.; Kovalev, N. F.; V. Palitsin, A.

    2016-12-01

    We consider the properties of thin-walled, strongly magnetized electron beams in closed evacuated transportation channels with arbitrary cross sections of the channel and the electron beam. Explicit precise formulas are obtained for the limiting and Fedosov's currents of such electron beams. The found relationships allow one to explain many observed phenomena and can serve as a basis for verification of the results of more complicated calculations.

  14. Unexpected strong magnetism of Cu doped single-layer MoS₂ and its origin.

    Science.gov (United States)

    Yun, Won Seok; Lee, J D

    2014-05-21

    The magnetism of the 3d transition-metal (TM) doped single-layer (1L) MoS2, where the Mo atom is partially replaced by the 3d TM atom, is investigated using the first-principles density functional calculations. In a series of 3d TM doped 1L-MoS2's, the induced spin polarizations are negligible for Sc, Ti, and Cr dopings, while the induced spin polarizations are confirmed for V, Mn, Fe, Co, Ni, Cu, and Zn dopings and the systems become magnetic. Especially, the Cu doped system shows unexpectedly strong magnetism although Cu is nonmagnetic in its bulk state. The driving force is found to be a strong hybridization between Cu 3d states and 3p states of neighboring S, which results in an extreme unbalanced spin-population in the spin-split impurity bands near the Fermi level. Finally, we also discuss further issues of the Cu induced magnetism of 1L-MoS2 such as investigation of additional charge states, the Cu doping at the S site instead of the Mo site, and the Cu adatom on the layer (i.e., 1L-MoS2).

  15. Numerical analysis of blood flow in realistic arteries subjected to strong non-uniform magnetic fields

    International Nuclear Information System (INIS)

    Kenjeres, Sasa

    2008-01-01

    The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier-Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell's equations (Biot-Savart/Ampere's law) for treating the imposed magnetic fields. The relevant hydrodynamic and electromagnetic properties of human blood were taken from the literature. The model is then validated for different test cases ranging from a simple cylindrical geometry to real-life right-coronary arteries in humans. The time-dependency of the wall-shear-stress for different stenosis growth rates and the effects of the imposed strong non-uniform magnetic fields on the blood flow pattern are presented and analysed. It is concluded that an imposed non-uniform magnetic field can create significant changes in the secondary flow patterns, thus making it possible to use this technique for optimisations of targeted drug delivery

  16. Anomaly disturbances of the magnetic fields before the strong earthquake in Japan on March 11, 2011

    Directory of Open Access Journals (Sweden)

    Masashi Hayakawa

    2012-04-01

    Full Text Available

    One of the strongest earthquakes, with magnitude M 8.9, occurred at the sea bottom near to the east coast of Japan on March 11, 2011. This study is devoted to the investigation of anomaly disturbances in the main magnetic field of the Earth and in ultra-low frequency magnetic variations (F <10 Hz observed before this earthquake. Secular variations of the main geomagnetic field were investigated using three-component 1-h data from three magnetic observatories over the 11-year period of January 1, 2000, to January 31, 2011. The Esashi and Mizusawa magnetic stations are situated northwest of the earthquake epicenter, at distances of around 170 km to 200 km, and the Kakioka observatory is situated southwest of the earthquake epicenter, at a distance of about 300 km. During this period, there were four local anomalies in the secular variations. The last anomaly was the biggest, which began around 3 years prior to the earthquake moment. All of the anomalies can be most distinctly recognized, in the form of differences in the corresponding magnetic components at these remote magnetic stations. For investigations of the ultra-low frequency magnetic field disturbances, three-component 1-s data at two magnetic stations (Kakioka and Uchiura were used. The Uchiura station is situated 119 km south of Kakioka, at a distance of about 420 km from the earthquake epicenter. Data from the time interval of February 18, 2011 to March 10, 2011 (only at night-time: 01:00 to 04:00 local time were investigated in a wide frequency range. In the frequency range of 0.033 Hz to 0.01 Hz, there was the clearest anomaly, seen as a decrease in the correlation coefficients of the corresponding magnetic components at these two stations, from February 22, 2011. Differences in the Z components showed an increase, and became positive after this date. This might suggest that the ultra-low frequency lithospheric source appeared north of the Kakioka station. Outside this specified

  17. Two regimes in conductivity and the Hall coefficient of underdoped cuprates in strong magnetic fields.

    Science.gov (United States)

    Gor'kov, L P; Teitel'baum, G B

    2014-01-29

    We address recent experiments shedding light on the energy spectrum of under and optimally doped cuprates at temperatures above the superconducting transition. Angle resolved photoemission reveals coherent excitation only near nodal points on parts of the 'bare' Fermi surface known as the Fermi arcs. The question debated in the literature is whether the small normal pocket, seen via quantum oscillations, exists at higher temperatures or forms below a charge order transition in strong magnetic fields. Assuming the former case as a possibility, expressions are derived for the resistivity and the Hall coefficient (in weak and strong magnetic fields) with both types of carriers participating in the transport. There are two regimes. At higher temperatures (at a fixed field) electrons are dragged by the Fermi arcs' holes. The pocket being small, its contribution to conductivity and the Hall coefficient is negligible. At lower temperatures electrons decouple from holes behaving as a Fermi gas in the magnetic field. As the mobility of holes on the arcs decreases in strong fields with a decrease of temperature, below a crossover point the pocket electrons prevail, changing the sign of the Hall coefficient in the low temperature limit. Such behavior finds its confirmation in recent high-field experiments.

  18. A strong magnetic field around the supermassive black hole at the centre of the Galaxy.

    Science.gov (United States)

    Eatough, R P; Falcke, H; Karuppusamy, R; Lee, K J; Champion, D J; Keane, E F; Desvignes, G; Schnitzeler, D H F M; Spitler, L G; Kramer, M; Klein, B; Bassa, C; Bower, G C; Brunthaler, A; Cognard, I; Deller, A T; Demorest, P B; Freire, P C C; Kraus, A; Lyne, A G; Noutsos, A; Stappers, B; Wex, N

    2013-09-19

    Earth's nearest candidate supermassive black hole lies at the centre of the Milky Way. Its electromagnetic emission is thought to be powered by radiatively inefficient accretion of gas from its environment, which is a standard mode of energy supply for most galactic nuclei. X-ray measurements have already resolved a tenuous hot gas component from which the black hole can be fed. The magnetization of the gas, however, which is a crucial parameter determining the structure of the accretion flow, remains unknown. Strong magnetic fields can influence the dynamics of accretion, remove angular momentum from the infalling gas, expel matter through relativistic jets and lead to synchrotron emission such as that previously observed. Here we report multi-frequency radio measurements of a newly discovered pulsar close to the Galactic Centre and show that the pulsar's unusually large Faraday rotation (the rotation of the plane of polarization of the emission in the presence of an external magnetic field) indicates that there is a dynamically important magnetic field near the black hole. If this field is accreted down to the event horizon it provides enough magnetic flux to explain the observed emission--from radio to X-ray wavelengths--from the black hole.

  19. Strong uniaxial magnetic anisotropy in Co films on highly ordered grating-like nanopatterned Ge surfaces

    Science.gov (United States)

    Alam Mollick, Safiul; Singh, Ranveer; Kumar, Mohit; Bhattacharyya, Satyaranjan; Som, Tapobrata

    2018-03-01

    We present a systematic investigation on uniaxial magnetic anisotropy (UMA) in Co thin films induced by high aspect ratio nanopatterned anisotropic substrates. Self-organized long grating-like nanostructures, with extreme regularities, are fabricated on Ge surfaces using Au-ion implantation at room temperature. Subsequently deposition of Co films are carried out on the same at two different angles. Magneto-optical Kerr effect measurements show strong UMA in Co films grown on ion-patterned Ge substrates, fabricated under different ion fluences, along and perpendicular to the direction of the patterns (long grating-like nanostructures). Magnetic force microscopy measurements under different externally applied magnetic fields reveal an easy domain wall motion when the field is applied along the grating-like nanostructures. On the other hand, high amplitude grating-like nanostructures hinder the spin rotation when the field is applied along the hard axis. The present study will be useful for magnetic recording media and ultra-small magnetic field sensors.

  20. Two-photon annihilation of thermal pairs in strong magnetic fields

    Science.gov (United States)

    Baring, Matthew G.; Harding, Alice K.

    1992-01-01

    The annihilation spectrum of pairs with 1-D thermal distributions in the presence of a strong magnetic field is calculated. Numerical analysis of the spectrum are performed for mildly relativistic temperatures and for different angles of emission with respect to field lines. Teragauss magnetic fields are assumed so that conditions are typical of gamma ray burst and pulsar environments. The spectra at each viewing angle reveal asymmetric line profiles that are signatures of the magnetic broadening and red shifting of the line: these asymmetries are more prominent for small viewing angles. Thermal Doppler broadening tends to dominate in the right wing of the line and obscures the magnetic broadening more at high temperatures and smaller viewing angles. This angular dependence of the line asymmetry may prove a valuable diagnostic tool. For low temperatures and magnetic field strengths, useful analytic expressions are presented for the line width, and also for the annihilation spectrum at zero viewing angle. The results presented find application in gamma ray burst and pulsar models, and may prove very helpful in deducing field strengths and temperatures of the emission regions of these objects from line observations made by Compton GRO and future missions.

  1. Strong post-midnight Equatorial Ionospheric Anomaly and Equatorial spread F Observations during magnetically quiet period

    Science.gov (United States)

    Moldwin, M. B.; Yizengaw, E.; Sahai, Y.

    2008-12-01

    Post sunset equatorial ionospheric irregularities, especially during magnetically active periods, have been a subject of many studies. The most prominent irregularities often observed right after sunset are the resurgence of the equatorial ionospheric anomaly (EIA) and equatorial spread F (ESF). It is well understood and documented that pre-reversal enhancement, due to the ionospheric conductivity gradient at the dusk, is one of the prime triggering mechanisms for the post-sunset irregularities in the equatorial region. However, less attention has been given to the equatorial irregularities (EIA and ESF) that often occur in post-midnight, especially during magnetically quiet periods. It has been suggested that the primary process responsible for the dramatic post-midnight ESF during magnetically active periods is the change in magnitude and direction of the usual equatorial electric field. Earlier studies speculated that during magnetically active post-midnight periods the change in electric field direction from westward to eastward for a short intervals cause an upward E × B drift, resulting in increased h'F and decreased electron densities at the magnetic equator. Individual scans of Jicamarca vertical drift also often observe significant upward drift during post-midnight periods. We present a case of post-midnight strong equatorial ionospheric anomaly during a magnetically quiet (Kp < 3) period using TOPEX altimeter TEC data. Simultaneously, the ionosonde station at S.J. Campos (23.2°S, 45.9°W; dip lat. 17.6°S) observed strong ESF and unusual h'F height rise during post-midnight period, where TOPEX detected strong EIA. At the same time ROCSAT-1 and DMSP satellites also clearly show existence of EIA during post-midnight period at their orbiting altitude. The former satellite also detected post-midnight in situ density irregularities (such as bubbles) at the same time as strong EIA and ESF. The questions here are what triggers these post-midnight equatorial

  2. Electron cyclotron maser instability (ECMI in strong magnetic guide field reconnection

    Directory of Open Access Journals (Sweden)

    R. A. Treumann

    2017-08-01

    Full Text Available The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is

  3. Electron cyclotron maser instability (ECMI) in strong magnetic guide field reconnection

    Science.gov (United States)

    Treumann, Rudolf A.; Baumjohann, Wolfgang

    2017-08-01

    The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales) electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR) in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects) involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is of particular

  4. Study of Fluid Flow Control in Protein Crystallization using Strong Magnetic Fields

    Science.gov (United States)

    Ramachandran, Narayanan; Leslie, Fred; Ciszak, Ewa

    2002-01-01

    An important component in biotechnology, particularly in the area of protein engineering and rational drug design is the knowledge of the precise three-dimensional molecular structure of proteins. The quality of structural information obtained from X-ray diffraction methods is directly dependent on the degree of perfection of the protein crystals. As a consequence, the growth of high quality macromolecular crystals for diffraction analyses has been the central focus for biochemists, biologists, and bioengineers. Macromolecular crystals are obtained from solutions that contain the crystallizing species in equilibrium with higher aggregates, ions, precipitants, other possible phases of the protein, foreign particles, the walls of the container, and a likely host of other impurities. By changing transport modes in general, i.e., reduction of convection and sedimentation, as is achieved in "microgravity", researchers have been able to dramatically affect the movement and distribution of macromolecules in the fluid, and thus their transport, formation of crystal nuclei, and adsorption to the crystal surface. While a limited number of high quality crystals from space flights have been obtained, as the recent National Research Council (NRC) review of the NASA microgravity crystallization program pointed out, the scientific approach and research in crystallization of proteins has been mainly empirical yielding inconclusive results. We postulate that we can reduce convection in ground-based experiments and we can understand the different aspects of convection control through the use of strong magnetic fields and field gradients. Whether this limited convection in a magnetic field will provide the environment for the growth of high quality crystals is still a matter of conjecture that our research will address. The approach exploits the variation of fluid magnetic susceptibility with concentration for this purpose and the convective damping is realized by appropriately

  5. Femtosecond switching of magnetism via strongly correlated spin-charge quantum excitations.

    Science.gov (United States)

    Li, Tianqi; Patz, Aaron; Mouchliadis, Leonidas; Yan, Jiaqiang; Lograsso, Thomas A; Perakis, Ilias E; Wang, Jigang

    2013-04-04

    The technological demand to push the gigahertz (10(9) hertz) switching speed limit of today's magnetic memory and logic devices into the terahertz (10(12) hertz) regime underlies the entire field of spin-electronics and integrated multi-functional devices. This challenge is met by all-optical magnetic switching based on coherent spin manipulation. By analogy to femtosecond chemistry and photosynthetic dynamics--in which photoproducts of chemical and biochemical reactions can be influenced by creating suitable superpositions of molecular states--femtosecond-laser-excited coherence between electronic states can switch magnetic order by 'suddenly' breaking the delicate balance between competing phases of correlated materials: for example, manganites exhibiting colossal magneto-resistance suitable for applications. Here we show femtosecond (10(-15) seconds) photo-induced switching from antiferromagnetic to ferromagnetic ordering in Pr0.7Ca0.3MnO3, by observing the establishment (within about 120 femtoseconds) of a huge temperature-dependent magnetization with photo-excitation threshold behaviour absent in the optical reflectivity. The development of ferromagnetic correlations during the femtosecond laser pulse reveals an initial quantum coherent regime of magnetism, distinguished from the picosecond (10(-12) seconds) lattice-heating regime characterized by phase separation without threshold behaviour. Our simulations reproduce the nonlinear femtosecond spin generation and underpin fast quantum spin-flip fluctuations correlated with coherent superpositions of electronic states to initiate local ferromagnetic correlations. These results merge two fields, femtosecond magnetism in metals and band insulators, and non-equilibrium phase transitions of strongly correlated electrons, in which local interactions exceeding the kinetic energy produce a complex balance of competing orders.

  6. He2+ molecular ion and the He- atomic ion in strong magnetic fields

    Science.gov (United States)

    Vieyra, J. C. Lopez; Turbiner, A. V.

    2017-08-01

    We study the question of existence, i.e., stability with respect to dissociation of the spin-quartet permutation- and reflection-symmetric 4(-3) +g (Sz=-3 /2 ,M =-3 ) state of the (α α e e e ) Coulomb system: the He2 + molecular ion, placed in a magnetic field 0 ≤B ≤10 000 a.u. We assume that the α particles are infinitely massive (Born-Oppenheimer approximation of zero order) and adopt the parallel configuration, when the molecular axis and the magnetic field direction coincide, as the optimal configuration. The study of the stability is performed variationally with a physically adequate trial function. To achieve this goal, we explore several helium-containing compounds in strong magnetic fields, in particular; we study the spin-quartet ground state of the He- ion and the ground (spin-triplet) state of the helium atom, both for a magnetic field in 100 ≤B ≤10 000 a.u. The main result is that the He2 + molecular ion in the state 4(-3) +g is stable towards all possible decay modes for magnetic fields B ≳120 a .u . and with the magnetic field increase the ion becomes more tightly bound and compact with a cigar-type form of electronic cloud. At B =1000 a .u . , the dissociation energy of He2 + into He-+α is ˜702 eV and the dissociation energy for the decay channel to He +α +e is ˜729 eV , and both energies are in the energy window for one of the observed absorption features of the isolated neutron star 1E1207.4-5209.

  7. Prostate Magnetic Resonance Imaging and Magnetic Resonance Imaging Targeted Biopsy in Patients with a Prior Negative Biopsy: A Consensus Statement by AUA and SAR.

    Science.gov (United States)

    Rosenkrantz, Andrew B; Verma, Sadhna; Choyke, Peter; Eberhardt, Steven C; Eggener, Scott E; Gaitonde, Krishnanath; Haider, Masoom A; Margolis, Daniel J; Marks, Leonard S; Pinto, Peter; Sonn, Geoffrey A; Taneja, Samir S

    2016-12-01

    After an initial negative biopsy there is an ongoing need for strategies to improve patient selection for repeat biopsy as well as the diagnostic yield from repeat biopsies. As a collaborative initiative of the AUA (American Urological Association) and SAR (Society of Abdominal Radiology) Prostate Cancer Disease Focused Panel, an expert panel of urologists and radiologists conducted a literature review and formed consensus statements regarding the role of prostate magnetic resonance imaging and magnetic resonance imaging targeted biopsy in patients with a negative biopsy, which are summarized in this review. The panel recognizes that many options exist for men with a previously negative biopsy. If a biopsy is recommended, prostate magnetic resonance imaging and subsequent magnetic resonance imaging targeted cores appear to facilitate the detection of clinically significant disease over standardized repeat biopsy. Thus, when high quality prostate magnetic resonance imaging is available, it should be strongly considered for any patient with a prior negative biopsy who has persistent clinical suspicion for prostate cancer and who is under evaluation for a possible repeat biopsy. The decision of whether to perform magnetic resonance imaging in this setting must also take into account the results of any other biomarkers and the cost of the examination, as well as the availability of high quality prostate magnetic resonance imaging interpretation. If magnetic resonance imaging is done, it should be performed, interpreted and reported in accordance with PI-RADS version 2 (v2) guidelines. Experience of the reporting radiologist and biopsy operator are required to achieve optimal results and practices integrating prostate magnetic resonance imaging into patient care are advised to implement quality assurance programs to monitor targeted biopsy results. Patients receiving a PI-RADS assessment category of 3 to 5 warrant repeat biopsy with image guided targeting. While

  8. Active galaxies. A strong magnetic field in the jet base of a supermassive black hole.

    Science.gov (United States)

    Martí-Vidal, Ivan; Muller, Sébastien; Vlemmings, Wouter; Horellou, Cathy; Aalto, Susanne

    2015-04-17

    Active galactic nuclei (AGN) host some of the most energetic phenomena in the universe. AGN are thought to be powered by accretion of matter onto a rotating disk that surrounds a supermassive black hole. Jet streams can be boosted in energy near the event horizon of the black hole and then flow outward along the rotation axis of the disk. The mechanism that forms such a jet and guides it over scales from a few light-days up to millions of light-years remains uncertain, but magnetic fields are thought to play a critical role. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we have detected a polarization signal (Faraday rotation) related to the strong magnetic field at the jet base of a distant AGN, PKS 1830-211. The amount of Faraday rotation (rotation measure) is proportional to the integral of the magnetic field strength along the line of sight times the density of electrons. The high rotation measures derived suggest magnetic fields of at least tens of Gauss (and possibly considerably higher) on scales of the order of light-days (0.01 parsec) from the black hole. Copyright © 2015, American Association for the Advancement of Science.

  9. Dynamics of liquid metal droplets and jets influenced by a strong axial magnetic field

    Science.gov (United States)

    Hernández, D.; Karcher, Ch

    2017-07-01

    Non-contact electromagnetic control and shaping of liquid metal free surfaces is crucial in a number of high-temperature metallurgical processes like levitation melting and electromagnetic sealing, among others. Other examples are the electromagnetic bending or stabilization of liquid metal jets that frequently occur in casting or fusion applications. Within this context, we experimentally study the influence of strong axial magnetic fields on the dynamics of falling metal droplets and liquid metal jets. GaInSn in eutectic composition is used as test melt being liquid at room temperature. In the experiments, we use a cryogen-free superconducting magnet (CFM) providing steady homogeneous fields of up to 5 T and allowing a tilt angle between the falling melt and the magnet axis. We vary the magnetic flux density, the tilt angle, the liquid metal flow rate, and the diameter and material of the nozzle (electrically conducting/insulating). Hence, the experiments cover a parameter range of Hartmann numbers Ha, Reynolds numbers Re, and Weber numbers We within 0 rotation ceases and the droplets are stretched in the field direction. Moreover, we observe that the jet breakup into droplets (spheroidization) is suppressed, and in the case of electrically conducting nozzles and tilt, the jets are bent towards the field axis.

  10. The mass limit of white dwarfs with strong magnetic fields in general relativity

    International Nuclear Information System (INIS)

    Wen De-Hua; Liu He-Lei; Zhang Xiang-Dong

    2014-01-01

    Recently, U. Das and B. Mukhopadhyay proposed that the Chandrasekhar limit of a white dwarf could reach a new high level (2.58M⊙) if a superstrong magnetic field were considered (Das U and Mukhopadhyay B 2013 Phys. Rev. Lett. 110 071102), where the structure of the strongly magnetized white dwarf (SMWD) is calculated in the framework of Newtonian theory (NT). As the SMWD has a far smaller size, in contrast with the usual expectation, we found that there is an obvious general relativistic effect (GRE) in the SMWD. For example, for the SMWD with a one Landau level system, the super-Chandrasekhar mass limit in general relativity (GR) is approximately 16.5% lower than that in NT. More interestingly, the maximal mass of the white dwarf will be first increased when the magnetic field strength keeps on increasing and reaches the maximal value M = 2.48M⊙ with B D = 391.5. Then if we further increase the magnetic fields, surprisingly, the maximal mass of the white dwarf will decrease when one takes the GRE into account. (geophysics, astronomy, and astrophysics)

  11. Photogeneration of neutrino and axions under stimulating effect of strong magnetic field

    CERN Document Server

    Skobelev, V V

    2001-01-01

    The processes of the neutrino and axions photoproduction on the gamma(Ze) -> gamma(nu nu-bar), gamma alpha nuclei, as well as the photon inelastic scattering on the gamma gamma -> gamma(nu nu-bar), gamma alpha photon are considered within the frames of the developed two-dimensional co-variant theory for calculating the matrix of the Feynman diagrams in the strong magnetic field. The contribution of the neutrino radiative photoproduction on the nuclei to the luminosity of the magnetic neutron stars on the early stages of their evolution may compete with the URCA-processes, because the matrix elements in the four-pole diagram depend linearly on the induction of B magnetic field by the B values approx 10 sup 3 -10 sup 4 B sub 0 (B sub 0 = m sub e sup 2 /|e| = 4.41 x 10 sup 1 sup 3 Gs). The evaluation of the axion mass upper boundary, compatible with other independent results, is obtained from the condition of the neutrino luminosity prevailing over the axion one at supposed temperature and magnetic field inducti...

  12. Ideal magnetohydrodynamic simulations of low beta compact toroid injection into a hot strongly magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wei [Los Alamos National Laboratory; Hsu, Scott [Los Alamos National Laboratory; Li, Hui [Los Alamos National Laboratory

    2009-01-01

    We present results from three-dimensional ideal magnetohydrodynamic simulations of low {beta} compact toroid (CT) injection into a hot strongly magnetized plasma, with the aim of providing insight into CT fueling of a tokamak with parameters relevant for ITER (International Thermonuclear Experimental Reactor). A regime is identified in terms of CT injection speed and CT-to-background magnetic field ratio that appears promising for precise core fueling. Shock-dominated regimes, which are probably unfavorable for tokamak fueling, are also identified. The CT penetration depth is proportional to the CT injection speed and density. The entire CT evolution can be divided into three stages: (1) initial penetration, (2) compression in the direction of propagation and reconnection, and (3) coming to rest and spreading in the direction perpendicular to injection. Tilting of the CT is not observed due to the fast transit time of the CT across the background plasma.

  13. Process γγ → νν-bar in a strong magnetic field

    International Nuclear Information System (INIS)

    Kuznetsov, A.V.; Mikheev, N.V.; Rumyantsev, D.A.

    2003-01-01

    The three-vertex loop amplitude in a strong magnetic field are analyzed in a general form by using the asymptotic behavior of the electron propagator in an external field. The process γγ → νν-bar is studied in terms of the scalar-vector-vector (SVV), pseudoscalar-vector-vector (PVV), vector-vector-vector (VVV), and axial-vector-vector-vector (AVV) combinations of couplings. It is shown that only in the case of the SVV combination does the amplitude grow linearly with increasing magnetic-field strength, the amplitudes evaluated with the other combinations of couplings (PVV, VVV, and AVV) featuring no linearly increasing terms. The process γγ → νν-bar is also studied within the left-right model, which is an extension of the Standard Model of electroweak interactions and which may involve an effective scalar ννee coupling. Possible astrophysical manifestations of this process are discussed

  14. Classical Spin Liquid Instability Driven By Off-Diagonal Exchange in Strong Spin-Orbit Magnets

    Science.gov (United States)

    Rousochatzakis, Ioannis; Perkins, Natalia B.

    2017-04-01

    We show that the off-diagonal exchange anisotropy drives Mott insulators with strong spin-orbit coupling to a classical spin liquid regime, characterized by an infinite number of ground states and Ising variables living on closed or open strings. Depending on the sign of the anisotropy, quantum fluctuations either fail to lift the degeneracy down to very low temperatures, or select noncoplanar magnetic states with unconventional spin correlations. The results apply to all 2D and 3D tricoordinated materials with bond-directional anisotropy and provide a consistent interpretation of the suppression of the x-ray magnetic circular dichroism signal reported recently for β -Li2IrO3 under pressure.

  15. Metal-insulator crossover in superconducting cuprates in strong magnetic fields

    International Nuclear Information System (INIS)

    Marchetti, P.A.; Su Zhaobin; Yu Lu

    2001-02-01

    The metal-insulator crossover of the in-plane resistivity upon temperature decrease, recently observed in several classes of cuprate superconductors, when a strong magnetic field suppresses the superconductivity, is explained using the U(1)xSU(2) Chern-Simons gauge field theory. The origin of this crossover is the same as that for a similar phenomenon observed in heavily underdoped cuprates without magnetic field. It is due to the interplay between the diffusive motion of the charge carriers and the 'peculiar' localization effect due to short-range antiferromagnetic order. We also calculate the in-plane transverse magnetoresistance which is in a fairly good agreement with available experimental data. (author)

  16. Resonance enhancement of two photon absorption by magnetically trapped atoms in strong rf-fields

    Science.gov (United States)

    Chakraborty, A.; Mishra, S. R.

    2018-01-01

    Applying a many mode Floquet formalism for magnetically trapped atoms interacting with a polychromatic rf-field, we predict a large two photon transition probability in the atomic system of cold 87Rb atoms. The physical origin of this enormous increase in the two photon transition probability is due to the formation of avoided crossings between eigen-energy levels originating from different Floquet sub-manifolds and redistribution of population in the resonant intermediate levels to give rise to the resonance enhancement effect. Other exquisite features of the studied atom-field composite system include the splitting of the generated avoided crossings at the strong field strength limit and a periodic variation of the single and two photon transition probabilities with the mode separation frequency of the polychromatic rf-field. This work can find applications to characterize properties of cold atom clouds in the magnetic traps using rf-spectroscopy techniques.

  17. The process γγ → νν-bar in a strong magnetic field

    International Nuclear Information System (INIS)

    Kuznetsov, A.V.; Mikheev, N.V.; Rumyantsev, D.A.

    2003-01-01

    A general analysis of the three-vertex loop amplitude in a strong magnetic field, based on the asymptotic form of the electron propagator in the field, is performed. In order to investigate the photon-neutrino process γγ → νν-bar, the vertex combinations of the scalar-vector-vector (SVV), pseudoscalar- vector-vector (PVV), 3-vector (VVV), and axial-vector-vector (AVV) types are considered. It is shown that only the SVV amplitude grows linearly with the magnetic-field strength, while in the other amplitudes, PVV, VVV, and AVV, the linearly growing terms are cancelled. The process γγ → νν-bar is investigated in the left-right-symmetric extension of the standard model of electroweak interaction, where the effective scalar ννee coupling could exist. Possible astrophysical manifestations of the considered process are discussed [ru

  18. Highly controlled orientation of CaBi4Ti4O15 using a strong magnetic field

    Science.gov (United States)

    Suzuki, Tohru S.; Kimura, Masahiko; Shiratsuyu, Kosuke; Ando, Akira; Sakka, Yoshio; Sakabe, Yukio

    2006-09-01

    The texture of feeble magnetic ceramics can be controlled by a strong magnetic field. When the magnetic susceptibility of the c axis is smaller than that of the other axes, the c axis aligns perpendicular to the magnetic field; however, the direction is randomly oriented on the plane perpendicular to the magnetic field. The authors demonstrate in this letter that a highly controlled texture in bismuth titanate, which has a c-axis susceptibility smaller than the other axes, can be achieved using a two-step magnetic field procedure. This highly controlled orientation is effective for improving the electromechanical coupling coefficient.

  19. Application of the nuclear liquid drop model to a negative hydrogen ion in the strong electric field of a laser

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, M.Ya.; Kornyushin, Y. [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)]. E-mail: yurik@vms.huji.ac.il

    2000-09-01

    The nuclear liquid drop model is applied to describe some basic properties of a negative hydrogen ion in the strong electric field of a laser. The equilibrium ionic size, energy and polarizability of the ion are calculated. Collective modes of the dipole oscillations are considered. A barrier which arises in a strong electric field is studied. The barrier vanishes at some large value of the electric field, which is defined as a critical value. The dependence of the critical field on frequency is studied. At frequencies {omega}{>=}({omega}{sub d}/2{sup 1/2}) ({omega}{sub d} is the frequency of the dipole oscillations of the electronic cloud relative to the nucleus) the barrier remains for any field. At high frequencies a 'stripping' mechanism for instability arises. At the resonant frequency a rather low amplitude of the electric field causes the 'stripping' instability. (author)

  20. Negative magnetization induced by Mn doping in YCrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Li, C.L. [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Huang, S. [Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou 310018 (China); Li, X.X.; Zhu, C.M.; Zerihun, G.; Yin, C.Y. [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Lu, C.L., E-mail: cllu@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Yuan, S.L., E-mail: yuansl@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2017-06-15

    Highlights: • Negative magnetization is firstly observed in Mn doped YCrO{sub 3} ceramics. • The phenomenon is originated from the antiferromagnetic coupling of three different interactions. • The increase of magnetization for samples is attributed to the ferromagnetic exchange interaction between Cr{sup 3+} and Mn{sup 3+}. - Abstract: A series of ceramic samples YCr{sub 1−x}Mn{sub x}O{sub 3} (0.15 ⩽ x ⩽ 0.4) with orthorhombic phase were prepared by a modified Pechini method, the structure and magnetic properties were studied in details. Our experiments revealed remarkable negative magnetization induced by the competition among multiple exchange interactions. The negative magnetization is result from the antiferromagnetic coupling of weak ferromagnetic moments of Mn{sup 3+}–Mn{sup 3+} and Cr{sup 3+}–Cr{sup 3+} with that of Cr{sup 3+}–Mn{sup 3+} interactions. And the strength of the magnetization is closely related to the temperature, magnetic field and the value of x. Below the compensation temperature, the absolute of negative magnetization firstly increases and then decreases with the increase of x, which is correlated with the weakening of Cr{sup 3+}–Cr{sup 3+} interaction and the enhancement of Mn{sup 3+}–Mn{sup 3+} interaction. The increase of magnetization obtained from the hysteresis loops is attributed to the ferromagnetic exchange interaction between Cr{sup 3+} and Mn{sup 3+}. Moreover, the magnetic switching by only changing the magnetic field strength and both normal and inverse magnetocaloric effects were demonstrated.

  1. Measurement of the negative muon anomalous magnetic moment to 0.7 ppm

    NARCIS (Netherlands)

    Bennett, GW; Bousquet, B; Brown, HN; Bunce, G; Carey, RM; Cushman, P; Danby, GT; Debevec, PT; Deile, M; Deng, H; Dhawan, SK; Druzhinin, VP; Duong, L; Farley, FJM; Fedotovich, GV; Gray, FE; Grigoriev, D; Grosse-Perdekamp, M; Grossmann, A; Hare, MF; Hertzog, DW; Huang, [No Value; Hughes, VW; Iwasaki, M; Jungmann, K; Kawall, D; Khazin, BI; Krienen, F; Kronkvist, [No Value; Lam, A; Larsen, R; Lee, YY; Logashenko, [No Value; McNabb, R; Meng, W; Miller, JP; Morse, WM; Nikas, D; Onderwater, CJG; Orlov, Y; Ozben, CS; Paley, JM; Peng, Q; Polly, CC; Pretz, J; Prigl, R; Putlitz, GZ; Qian, T; Redin, SI; Rind, O; Roberts, BL; Ryskulov, N; Semertzidis, YK; Shagin, P; Shatunov, YM; Sichtermann, EP; Solodov, E; Sossong, M; Sulak, LR; Trofimov, A; von Walter, P; Yamamoto, A; Huang, X; Kronkvist, I.; Logashenko, I.; Özben, C.S.; Polley, C.C.; Shatunov, Yu.M.; von Walter, R.

    2004-01-01

    The anomalous magnetic moment of the negative muon has been measured to a precision of 0.7 ppm (ppm) at the Brookhaven Alternating Gradient Synchrotron. This result is based on data collected in 2001, and is over an order of magnitude more precise than the previous measurement for the negative muon.

  2. Strong Coupling of Microwave Photons to Antiferromagnetic Fluctuations in an Organic Magnet

    Science.gov (United States)

    Mergenthaler, Matthias; Liu, Junjie; Le Roy, Jennifer J.; Ares, Natalia; Thompson, Amber L.; Bogani, Lapo; Luis, Fernando; Blundell, Stephen J.; Lancaster, Tom; Ardavan, Arzhang; Briggs, G. Andrew D.; Leek, Peter J.; Laird, Edward A.

    2017-10-01

    Coupling between a crystal of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium radicals and a superconducting microwave resonator is investigated in a circuit quantum electrodynamics (circuit QED) architecture. The crystal exhibits paramagnetic behavior above 4 K, with antiferromagnetic correlations appearing below this temperature, and we demonstrate strong coupling at base temperature. The magnetic resonance acquires a field angle dependence as the crystal is cooled down, indicating anisotropy of the exchange interactions. These results show that multispin modes in organic crystals are suitable for circuit QED, offering a platform for their coherent manipulation. They also utilize the circuit QED architecture as a way to probe spin correlations at low temperature.

  3. An analytical method for the investigation of instability of a collisionless plasma in strong magnetic fields

    International Nuclear Information System (INIS)

    Zakharov, V.U.

    1993-01-01

    An analytical method for the investigation of special types of dispersion relations is presented. In particular, analysis of the propagation of small-amplitude hydromagnetic waves in a collisionless plasma in a strong magnetic field leads to such dispersion relations. The fifth-degree dispersion relation corresponding to a particular case is considered. The necessary stability condition for a steady state and conditions for the degeneration of small-amplitude waves are derived. A comparison with other methods for the analysis of similar dispersion relations is also presented. (author)

  4. Integrated electronic transport and thermometry at milliKelvin temperatures and in strong magnetic fields.

    Science.gov (United States)

    Samkharadze, N; Kumar, A; Manfra, M J; Pfeiffer, L N; West, K W; Csáthy, G A

    2011-05-01

    We fabricated a He-3 immersion cell for transport measurements of semiconductor nanostructures at ultra low temperatures and in strong magnetic fields. We have a new scheme of field-independent thermometry based on quartz tuning fork Helium-3 viscometry which monitors the local temperature of the sample's environment in real time. The operation and measurement circuitry of the quartz viscometer is described in detail. We provide evidence that the temperature of two-dimensional electron gas confined to a GaAs quantum well follows the temperature of the quartz viscometer down to 4 mK.

  5. Laser-driven platform for generation and characterization of strong quasi-static magnetic fields

    Czech Academy of Sciences Publication Activity Database

    Santos, J.J.; Bailly-Grandvaux, M.; Giuffrida, Lorenzo; Forestier-Colleoni, P.; Fujioka, H.; Zhang, Z.; Korneev, P.; Bouillaud, R.; Dorard, S.; Batani, D.; Chevrot, M.; Cross, J. E.; Crowston, R.; Dubois, J.L.; Gazave, J.; Gregori, G.; d'Humieres, E.; Hulin, S.; Ishihara, K.; Kojima, S.; Loyez, E.; Marqués, J.-R.; Morace, A.; Nicolaï, P.; Peyrusse, O.; Poyé, A.; Raffestin, D.; Ribolzi, J.; Roth, M.; Schaumann, G.; Serres, F.; Tikhonchuk, V.T.; Vacar, P.; Woolsey, N.

    2015-01-01

    Roč. 17, Aug (2015), s. 1-10, č. článku 083051. ISSN 1367-2630 R&D Projects: GA MŠk ED1.1.00/02.0061 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061 Institutional support: RVO:68378271 Keywords : strong magnetic field * laser-driven coil targets * laser-plasma interaction Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.570, year: 2015

  6. Energy density and energy flow of surface waves in a strongly magnetized graphene

    Science.gov (United States)

    Moradi, Afshin

    2018-01-01

    General expressions for the energy density and energy flow of plasmonic waves in a two-dimensional massless electron gas (as a simple model of graphene) are obtained by means of the linearized magneto-hydrodynamic model and classical electromagnetic theory when a strong external magnetic field perpendicular to the system is present. Also, analytical expressions for the energy velocity, wave polarization, wave impedance, transverse and longitudinal field strength functions, and attenuation length of surface magneto-plasmon-polariton waves are derived, and numerical results are prepared.

  7. Can we bet on negative emissions to achieve the 2°C target even under strong carbon cycle feedbacks?

    Science.gov (United States)

    Tanaka, K.; Yamagata, Y.; Yokohata, T.; Emori, S.; Hanaoka, T.

    2015-12-01

    Negative emission technologies such as Bioenergy with Carbon dioxide Capture and Storage (BioCCS) play an ever more crucial role in meeting the 2°C stabilization target. However, such technologies are currently at their infancy and their future penetrations may fall short of the scale required to stabilize the warming. Furthermore, the overshoot in the mid-century prior to a full realization of negative emissions would give rise to a risk because such a temporal but excessive warming above 2°C might amplify itself by strengthening climate-carbon cycle feedbacks. It has not been extensively assessed yet how carbon cycle feedbacks might play out during the overshoot in the context of negative emissions. This study explores how 2°C stabilization pathways, in particular those which undergo overshoot, can be influenced by carbon cycle feedbacks and asks their climatic and economic consequences. We compute 2°C stabilization emissions scenarios under a cost-effectiveness principle, in which the total abatement costs are minimized such that the global warming is capped at 2°C. We employ a reduced-complexity model, the Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate model (ACC2), which comprises a box model of the global carbon cycle, simple parameterizations of the atmospheric chemistry, and a land-ocean energy balance model. The total abatement costs are estimated from the marginal abatement cost functions for CO2, CH4, N2O, and BC.Our preliminary results show that, if carbon cycle feedbacks turn out to be stronger than what is known today, it would incur substantial abatement costs to keep up with the 2°C stabilization goal. Our results also suggest that it would be less expensive in the long run to plan for a 2°C stabilization pathway by considering strong carbon cycle feedbacks because it would cost more if we correct the emission pathway in the mid-century to adjust for unexpectedly large carbon cycle feedbacks during overshoot. Furthermore, our

  8. Magnetotransport properties of Cr1−δTe thin films with strong perpendicular magnetic anisotropy

    Directory of Open Access Journals (Sweden)

    L. Zhou

    2017-12-01

    Full Text Available P-type ferromagnetic Cr1-δTe thin films with the Curie temperature of 170K were epitaxially grown on GaAs substrate. Low-temperature magnetotransport study reveals that the film has a strong perpendicular magnetic anisotropy (PMA and an anisotropic magnetoresistance (AMR ratio up to 8.1%. Furthermore, reduced anomalous Hall effect is observed at low temperatures in Cr1-δTe, suggesting the possible crossover of the contribution to AHE from the intrinsic mechanism to extrinsic skew scattering. Distinctive from conventional transition metal ferromagnets, the AMR ratio is also greatly suppressed at low temperatures. Our work demonstrates that epitaxial Cr1-δTe films are interesting platforms for studying the physics underlying the strong PMA and large AMR.

  9. Density-matrix-functional calculations for matter in strong magnetic fields: Ground states of heavy atoms

    DEFF Research Database (Denmark)

    Johnsen, Kristinn; Yngvason, Jakob

    1996-01-01

    We report on a numerical study of the density matrix functional introduced by Lieb, Solovej, and Yngvason for the investigation of heavy atoms in high magnetic fields. This functional describes exactly the quantum mechanical ground state of atoms and ions in the limit when the nuclear charge Z...... and the electron number N tend to infinity with N/Z fixed, and the magnetic field B tends to infinity in such a way that B/Z4/3→∞. We have calculated electronic density profiles and ground-state energies for values of the parameters that prevail on neutron star surfaces and compared them with results obtained...... by other methods. For iron at B=1012 G the ground-state energy differs by less than 2% from the Hartree-Fock value. We have also studied the maximal negative ionization of heavy atoms in this model at various field strengths. In contrast to Thomas-Fermi type theories atoms can bind excess negative charge...

  10. Study of Fluid Flow Control in Protein Crystallization using Strong Magnetic Fields

    Science.gov (United States)

    Ramachandran, Narayanan; Leslie, Fred; Ciszak, Ewa

    2002-11-01

    An important component in biotechnology, particularly in the area of protein engineering and rational drug design is the knowledge of the precise three-dimensional molecular structure of proteins. The quality of structural information obtained from X-ray diffraction methods is directly dependent on the degree of perfection of the protein crystals. As a consequence, the growth of high quality macromolecular crystals for diffraction analyses has been the central focus for biochemists, biologists, and bioengineers. Macromolecular crystals are obtained from solutions that contain the crystallizing species in equilibrium with higher aggregates, ions, precipitants, other possible phases of the protein, foreign particles, the walls of the container, and a likely host of other impurities. By changing transport modes in general, i.e., reduction of convection and sedimentation, as is achieved in "microgravity", researchers have been able to dramatically affect the movement and distribution of macromolecules in the fluid, and thus their transport, formation of crystal nuclei, and adsorption to the crystal surface. While a limited number of high quality crystals from space flights have been obtained, as the recent National Research Council (NRC) review of the NASA microgravity crystallization program pointed out, the scientific approach and research in crystallization of proteins has been mainly empirical yielding inconclusive results. We postulate that we can reduce convection in ground-based experiments and we can understand the different aspects of convection control through the use of strong magnetic fields and field gradients. Whether this limited convection in a magnetic field will provide the environment for the growth of high quality crystals is still a matter of conjecture that our research will address. The approach exploits the variation of fluid magnetic susceptibility with concentration for this purpose and the convective damping is realized by appropriately

  11. Charge transfer of He2 + with H in a strong magnetic field

    Science.gov (United States)

    Liu, Chun-Lei; Zou, Shi-Yang; He, Bin; Wang, Jian-Guo

    2015-09-01

    By solving a time-dependent Schrödinger equation (TDSE), we studied the electron capture process in the He2 + +H collision system under a strong magnetic field in a wide projectile energy range. The strong enhancement of the total charge transfer cross section is observed for the projectile energy below 2.0 keV/u. With the projectile energy increasing, the cross sections will reduce a little and then increase again, compared with those in the field-free case. The cross sections to the states with different magnetic quantum numbers are presented and analyzed where the influence due to Zeeman splitting is obviously found, especially in the low projectile energy region. The comparison with other models is made and the tendency of the cross section varying with the projectile energy is found closer to that from other close coupling models. Project supported by the National Natural Science Foundation of China (Grants Nos. 11104017, 11025417, 11275029, and 11474032), the National Basic Research Programm of China (Grant No. 2013CB922200), and the Foundation for the Development of Science and Technology of the Chinese Academy of Engineering Physics (Grant Nos. 2014B09036 and 2013A0102005).

  12. Breakdown of the Chiral Anomaly in Weyl Semimetals in a Strong Magnetic Field

    Science.gov (United States)

    Kim, Pilkwang; Ryoo, Ji Hoon; Park, Cheol-Hwan

    2017-12-01

    The low-energy quasiparticles of Weyl semimetals are a condensed-matter realization of the Weyl fermions introduced in relativistic field theory. Chiral anomaly, the nonconservation of the chiral charge under parallel electric and magnetic fields, is arguably the most important phenomenon of Weyl semimetals and has been explained as an imbalance between the occupancies of the gapless, zeroth Landau levels with opposite chiralities. This widely accepted picture has served as the basis for subsequent studies. Here we report the breakdown of the chiral anomaly in Weyl semimetals in a strong magnetic field based on ab initio calculations. A sizable energy gap that depends sensitively on the direction of the magnetic field may open up due to the mixing of the zeroth Landau levels associated with the opposite-chirality Weyl points that are away from each other in the Brillouin zone. Our study provides a theoretical framework for understanding a wide range of phenomena closely related to the chiral anomaly in topological semimetals, such as magnetotransport, thermoelectric responses, and plasmons, to name a few.

  13. Strong Static Magnetic Fields Increase the Gel Signal in Partially Hydrated DPPC/DMPC Membranes

    Directory of Open Access Journals (Sweden)

    Jennifer Tang

    2015-09-01

    Full Text Available NIt was recently reported that static magnetic fields increase lipid order in the hydrophobic membrane core of dehydrated native plant plasma membranes [Poinapen, Soft Matter 9:6804-6813, 2013]. As plasma membranes are multicomponent, highly complex structures, in order to elucidate the origin of this effect, we prepared model membranes consisting of a lipid species with low and high melting temperature. By controlling the temperature, bilayers coexisting of small gel and fluid domains were prepared as a basic model for the plasma membrane core. We studied molecular order in mixed lipid membranes made of dimyristoyl-sn-glycero-3-phosphocholine (DMPC and dipalmitoyl-sn-glycero-3-phosphocholine (DPPC using neutron diffraction in the presence of strong static magnetic fields up to 3.5 T. The contribution of the hydrophobic membrane core was highlighted through deuterium labeling the lipid acyl chains. There was no observable effect on lipid organization in fluid or gel domains at high hydration of the membranes. However, lipid order was found to be enhanced at a reduced relative humidity of 43%: a magnetic field of 3.5 T led to an increase of the gel signal in the diffraction patterns of 5%. While all biological materials have weak diamagnetic properties, the corresponding energy is too small to compete against thermal disorder or viscous effects in the case of lipid molecules. We tentatively propose that the interaction between the fatty acid chains’ electric moment and the external magnetic field is driving the lipid tails in the hydrophobic membrane core into a better ordered state.

  14. Strong Static Magnetic Fields Increase the Gel Signal in Partially Hydrated DPPC/DMPC Membranes.

    Science.gov (United States)

    Tang, Jennifer; Alsop, Richard J; Schmalzl, Karin; Epand, Richard M; Rheinstädter, Maikel C

    2015-09-29

    NIt was recently reported that static magnetic fields increase lipid order in the hydrophobic membrane core of dehydrated native plant plasma membranes [Poinapen, Soft Matter 9:6804-6813, 2013]. As plasma membranes are multicomponent, highly complex structures, in order to elucidate the origin of this effect, we prepared model membranes consisting of a lipid species with low and high melting temperature. By controlling the temperature, bilayers coexisting of small gel and fluid domains were prepared as a basic model for the plasma membrane core. We studied molecular order in mixed lipid membranes made of dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) using neutron diffraction in the presence of strong static magnetic fields up to 3.5 T. The contribution of the hydrophobic membrane core was highlighted through deuterium labeling the lipid acyl chains. There was no observable effect on lipid organization in fluid or gel domains at high hydration of the membranes. However, lipid order was found to be enhanced at a reduced relative humidity of 43%: a magnetic field of 3.5 T led to an increase of the gel signal in the diffraction patterns of 5%. While all biological materials have weak diamagnetic properties, the corresponding energy is too small to compete against thermal disorder or viscous effects in the case of lipid molecules. We tentatively propose that the interaction between the fatty acid chains' electric moment and the external magnetic field is driving the lipid tails in the hydrophobic membrane core into a better ordered state.

  15. Strong coupling operation of a free-electron-laser amplifier with an axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rullier, J.L.; Devin, A.; Gardelle, J.; Labrouche, J.; Le Taillandier, P. [Commissariat a lEnergie Atomique, Boite Postale 2, 33114 Le Barp (France); Donohue, J.T. [Centre dEtudes Nucleaires de Bordeaux-Gradignan, Boite Postale 120, 33175 Gradignan (France)

    1996-03-01

    We present the results of a free-electron-laser (FEL) experiment at 35 GHz, using a strongly relativistic electron beam ({ital T}=1.75 MeV). The electron pulse length is 30 ns full width at half maximum with a peak current of 400 A. The FEL is designed to operate in the high-gain Compton regime, with a negative coupling parameter ({Phi}{lt}0) leading to a strong growth rate. More than 50 MW of rf power in the TE{sub 1}{sub 1} mode (43 dB gain) has been obtained with good reproducibility. The experimental results are in good agreement with predictions made using the three-dimensional stationary simulation code solitude. {copyright} {ital 1996 The American Physical Society.}

  16. Tiny Stars, Strong Fields: Exploring the Origin of Intense Magnetism in M Stars

    Science.gov (United States)

    Toomre, Juri

    . We bring to this our prior experience with studying dynamo processes in the outer convective envelopes of G- (the Sun) and Ftype stars, briefly of M dwarfs, and in full convective cores within more massive A- and B-type stars. Our previous work suggests that M dwarfs could display a broad range of dynamo behavior, from cyclic reversals to more chaotic variations, and further to both weak and strong dynamo states. We will focus on the latter, exploring how superequipartition magnetic fields could be achieved by dynamo action in M dwarfs, as are likely needed to energize super-flares and huge active regions, and what limits the peak field strengths. M-type stars are distinctive in becoming fully convective with decreasing mass at about M3.5 in spectral type (or about 0.35 solar masses). At this transition, a steep rise in the fraction of magnetically active stars is observed that is accompanied by an increasing rotational velocity. Clearly how mass-loss and spin-down can lead to this is of interest in itself. However, here we propose to study the manner in which dynamos operating in fully convective M dwarf interiors beyond the transition may be able to achieve very strong magnetic fields, and how field strengths and apparent magnetic activity increases with rotation rate as suggested by observations. We believe that global connectivity of flows and fields across the core center will admit new classes of strong behavior, as revealed by our B star core dynamos, not realized when a convective envelope is bounded below by a tachocline. These ideas need to be tested in a self-consistent manner with global ASH simulations to gain theoretical insights into what is the origin of the fierce magnetic activity in some of M dwarfs that may be potential hosts to Earth-like planets. Such 3-D MHD simulations, though challenging, are now feasible and would complement the intensive observational searches under way.

  17. Lactate dehydrogenase has no control on lactate production but has a strong negative control on formate production in Lactococcus lactis

    DEFF Research Database (Denmark)

    Andersen, H.W.; Pedersen, M.B.; Hammer, Karin

    2001-01-01

    a homolactic pattern of fermentation. Only after lactate dehydrogenase activity was reduced ninefold compared to the wild-type was the growth rate significantly affected, and the ldh mutants started to produce mixed-acid products (formate, acetate, and ethanol in addition to lactate). Flux control coefficients...... enhanced in the strain deleted for lactate dehydrogenase. What is more surprising is that the enzyme had a strong negative control (C- LDH(F1)J=-1.3) on the flux to formate at the wild-type level of lactate dehydrogenase. Furthermore, we showed that L. lactis has limited excess of capacity of lactate...... dehydrogenase, only 70% more than needed to catalyze the lactate flux in the wild- type cells....

  18. Strong impact of lattice vibrations on electronic and magnetic properties of paramagnetic Fe revealed by disordered local moments molecular dynamics

    NARCIS (Netherlands)

    Alling, B.; Kormann, F.H.W.; Grabowski, B; Glensk, A; Abrikosov, I.A.

    2016-01-01

    We study the impact of lattice vibrations on magnetic and electronic properties of paramagnetic bcc and fcc iron at finite temperature, employing the disordered local moments molecular dynamics (DLM-MD) method. Vibrations strongly affect the distribution of local magnetic moments at finite

  19. Asymptotic behaviour of the equilibrium nuclear separation for the H{sup +}{sub 2} molecule in a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Benguria, Rafael [Pontificia Universidad Catolica de Chile, Departamento de Fisica, Casilla 306, Santiago 22, Chile (Chile); Brummelhuis, Raymond [School of Economics, Mathematics and Statistics, 7-15 Gresse Street, University of London (United Kingdom); Duclos, Pierre [Centre de Physique Theorique UMR 6207-Unite Mixte de Recherche du CNRS et des Universites Aix-Marseille I, Aix-Marseille II et de l' Universite du Sud Toulon-Var-Laboratoire affilie a la FRUMAM, Luminy Case 907, F-13288 Marseille Cedex 9 (France); Perez-Oyarzun, Santiago [Instituto de Ciencias Basicas, Facultad de Ingenieria, Universidad Diego Portales, Av. Ejercito 441, Casilla 298-v, Santiago (Chile); Vytras, Petr [Katedra Matematiky, FJFI, CVUT, Trojanova 13, CZ-Prague 12000 (Czech Republic)

    2006-06-30

    We consider the hydrogen molecular ion H{sup +}{sub 2} in the fixed nuclear approximation, in the presence of a strong homogeneous magnetic field. We determine the leading asymptotic behaviour for the equilibrium distance between the nuclei of this molecule in the limit when the strength of the magnetic field goes to infinity.

  20. Tendon progenitor cells in injured tendons have strong chondrogenic potential: the CD105-negative subpopulation induces chondrogenic degeneration.

    Science.gov (United States)

    Asai, Shuji; Otsuru, Satoru; Candela, Maria Elena; Cantley, Leslie; Uchibe, Kenta; Hofmann, Ted J; Zhang, Kairui; Wapner, Keith L; Soslowsky, Louis J; Horwitz, Edwin M; Enomoto-Iwamoto, Motomi

    2014-12-01

    To study the cellular mechanism of the tendon repair process, we used a mouse Achilles tendon injury model to focus on the cells recruited to the injured site. The cells isolated from injured tendon 1 week after the surgery and uninjured tendons contained the connective tissue progenitor populations as determined by colony-forming capacity, cell surface markers, and multipotency. When the injured tendon-derived progenitor cells (inTPCs) were transplanted into injured Achilles tendons, they were not only integrated in the regenerating area expressing tenogenic phenotype but also trans-differentiated into chondrogenic cells in the degenerative lesion that underwent ectopic endochondral ossification. Surprisingly, the micromass culture of the inTPCs rapidly underwent chondrogenic differentiation even in the absence of exogenous bone morphogenetic proteins or TGFβs. The cells isolated from human ruptured tendon tissues also showed connective tissue progenitor properties and exhibited stronger chondrogenic ability than bone marrow stromal cells. The mouse inTPCs contained two subpopulations one positive and one negative for CD105, a coreceptor of the TGFβ superfamily. The CD105-negative cells showed superior chondrogenic potential in vitro and induced larger chondroid degenerative lesions in mice as compared to the CD105-positive cells. These findings indicate that tendon progenitor cells are recruited to the injured site of tendons and have a strong chondrogenic potential and that the CD105-negative population of these cells would be the cause for chondroid degeneration in injured tendons. The newly identified cells recruited to the injured tendon may provide novel targets to develop therapeutic strategies to facilitate tendon repair. © 2014 AlphaMed Press.

  1. Semiclassical quantization of integrable systems of few interacting anyons in a strong magnetic field

    International Nuclear Information System (INIS)

    Sivan, N.; Levit, S.

    1992-01-01

    We present a semiclassical theory of charged interacting anyons in a strong magnetic field. We derive the appropriate generalization of the WKB quantization conditions and determine the corresponding wave functions for non separable integrable anyonic systems. This theory is applies to a system of two interacting anyons, two interacting anyons in the presence of an impurity and three interacting anyons. We calculate the dependence of the semiclassical energy levels on the statistical parameter and find regions in which dependence follows very different patterns. The semiclassical treatment allows to find the correlation between these patterns and the change in the character of the classical motion of the system. We also test the accuracy of the mean field approximation for low and high energy states of the three anyons. (author)

  2. Influence of strong magnetic fields on laser pulse propagation in underdense plasma

    Science.gov (United States)

    Wilson, T. C.; Li, F. Y.; Weikum, M.; Sheng, Z. M.

    2017-06-01

    We examine the interaction between intense laser pulses and strongly magnetised plasmas in the weakly relativistic regime. An expression for the electron Lorentz factor coupling both relativistic and cyclotron motion nonlinearities is derived for static magnetic fields along the laser propagation axis. This is applied to predict modifications to the refractive index, critical density, group velocity dispersion and power threshold for relativistic self-focusing. It is found that electron quiver response is enhanced under right circularly-polarised light, decreasing the power threshold for various instabilities, while a dampening effect occurs under left circularly-polarised light, increasing the power thresholds. Derived theoretical predictions are tested by one- and three-dimensional particle-in-cell simulations.

  3. Oblique propagation of solitary waves in weakly relativistic magnetized plasma with kappa distributed electrons in the presence of negative ions

    Science.gov (United States)

    Salmanpoor, H.; Sharifian, M.; Gholipour, S.; Borhani Zarandi, M.; Shokri, B.

    2018-03-01

    The oblique propagation of nonlinear ion acoustic solitary waves (solitons) in magnetized collisionless and weakly relativistic plasma with positive and negative ions and super thermal electrons has been examined by using reduced perturbation method to obtain the Korteweg-de Vries equation that admits an obliquely propagating soliton solution. We have investigated the effects of plasma parameters like negative ion density, electrons temperature, angle between wave vector and magnetic field, ions velocity, and k (spectral index in kappa distribution) on the amplitude and width of solitary waves. It has been found out that four modes exist in our plasma model, but the analysis of the results showed that only two types of ion acoustic modes (fast and slow) exist in the plasma and in special cases only one mode could be propagated. The parameters of plasma for these two modes (or one mode) determine which one is rarefactive and which one is compressive. The main parameter is negative ions density (β) indicating which mode is compressive or rarefactive. The effects of the other plasma parameters on amplitude and width of the ion acoustic solitary waves have been studied. The main conclusion is that the effects of the plasma parameters on amplitude and width of the solitary wave strongly depend on the value of the negative ion density.

  4. Hot electromagnetic outflows. III. Displaced fireball in a strong magnetic field

    International Nuclear Information System (INIS)

    Thompson, Christopher; Gill, Ramandeep

    2014-01-01

    The evolution of a dilute electron-positron fireball is calculated in the regime of strong magnetization and high compactness (ℓ ∼ 10 3 -10 8 ). Heating is applied at a low effective temperature (<25 keV), appropriate to breakout from a confining medium, so that relaxation to a blackbody is inhibited by pair annihilation. The diffusion equation for Compton scattering by thermal pairs is coupled to a trans-relativistic cyclo-synchrotron source. We find that the photon spectrum develops a quasi-thermal peak at energy ∼0.1 m e c 2 in the comoving frame, with a power-law slope below it that is characteristic of gamma-ray bursts (GRBs; F ω ∼ const). The formation of a thermal high-energy spectrum is checked using the full kinetic equations. Calculations for a baryon-dominated photosphere reveal a lower spectral peak energy, and a harder low-energy spectrum, unless ion rest mass carries ≲ 10 –5 of the energy flux. We infer that (1) the GRB spectrum is inconsistent with the neutron-rich wind emitted by a young magnetar or neutron torus, and points to an event horizon in the engine; (2) neutrons play a negligible role in prompt gamma-ray emission; (3) the relation between observed peak frequency and burst energy is bounded below by the observed Amati relation if the Lorentz factor ∼(opening angle) –1 at breakout, and the jet is surrounded by a broader sheath that interacts with a collapsing stellar core; (4) X-ray flashes are consistent with magnetized jets with ion-dominated photospheres; (5) high-frequency Alfvén waves may become charge starved in the dilute pair gas; (6) limitations on magnetic reconnection from plasma collisionality have been overestimated.

  5. Global Pc5 pulsations during strong magnetic storms: excitation mechanisms and equatorward expansion

    Science.gov (United States)

    Marin, J. A.; Pilipenko, V.; Vega, P.; Zesta, E.; Stepanova, M. V.; Uozumi, T.

    2012-12-01

    The spatial structure of Pc5 waves during the recovery phases of strong magnetic storms is important not only for the identification of possible physical mechanisms of its excitation, but as an important parameter of the ULF driver of relativistic electrons. The dynamics of global Pc5 waves during the magnetic storms on October 29-31, 2003 and May 15, 2005 is studied, using the data from the trans-American network of magnetometers comprising SAMBA, MAGDAS, CARISMA, and MACCS arrays. We study the behavior of Pc5 wave properties and spectral characteristics with respect to latitude. One of the accepted sources of Pc5 wave activity is Kelvin-Helmholtz instability in the flanks of the magnetosphere. In our study we examine whether the KH instability is sufficient as an excitation mechanism for the observed waves? More specifically, we attempt to determine, what is the Pc5 wave generation type: self-excitation, resonant response, trigger? While the KH instability generation takes place at the outer flanks of the magnetosphere, Pc5 waves are observed at all latitudes. We determine how deep into the magnetosphere these Pc5 waves activity can extend and what is the wave energy transmission mechanism: surface mode, cavity mode, Alfven field-line resonance, magnetospheric MHD waveguide?

  6. Disorder effects on helical edge transport in graphene under a strong tilted magnetic field

    Science.gov (United States)

    Huang, Chunli; Cazalilla, Miguel A.

    2015-10-01

    In a recent experiment, Young et al. [Nature (London) 505, 528 (2014), 10.1038/nature12800] observed a metal to insulator transition as well as transport through helical edge states in monolayer graphene under a strong, tilted magnetic field. Under such conditions, the bulk is a magnetic insulator which can exhibit metallic conduction through helical edges. It was found that the two-terminal conductance of the helical channels deviates from the expected quantized value (=e2/h per edge, at zero temperature). Motivated by this observation, we study the effect of disorder on the conduction through the edge channels. We show that, unlike for helical edges of topological insulators in semiconducting quantum wells, a disorder Rashba spin-orbit coupling does not lead to backscattering, at least to leading order. Instead, we find that the lack of perfect antialignment of the electron spins in the helical channels to be the most likely cause for backscattering arising from scalar (i.e., spin-independent) impurities. The intrinsic spin-orbit coupling and other time-reversal symmetry-breaking and/or sublattice parity-breaking potentials also lead to (subleading) corrections to the channel conductance.

  7. Structure, magnetism, and theoretical study of a mixed-valence Co(II)3Co(III)4 heptanuclear wheel: lack of SMM behavior despite negative magnetic anisotropy.

    Science.gov (United States)

    Chibotaru, Liviu F; Ungur, Liviu; Aronica, Christophe; Elmoll, Hani; Pilet, Guillaume; Luneau, Dominique

    2008-09-17

    A mixed-valence Co(II)/Co(III) heptanuclear wheel [Co(II)3Co(III)4(L)6(MeO)6] (LH2 = 1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one) has been synthesized and its crystal structure determined using single-crystal X-ray diffraction. The valence state of each cobalt ion was established by bond valence sum calculations. Studies of the temperature dependence of the magnetic susceptibility and the field dependence of the magnetization evidence ferromagnetic interactions within the compound. In order to understand the magnetic properties of this Co7 wheel, we performed ab initio calculations for each cobalt fragment at the CASSCF/CASPT2 level, including spin-orbit coupling effects within the SO-RASSI approach. The four Co(III) ions were found to be diamagnetic and to give a significant temperature-independent paramagnetic contribution to the susceptibility. The spin-orbit coupling on the three Co(II) sites leads to separations of approximately 200 cm(-1) between the ground and excited Kramers doublets, placing the Co7 wheel into a weak-exchange limit in which the lowest electronic states are adequately described by the anisotropic exchange interaction between the lowest Kramers doublets on Co(II) sites. Simulation of the exchange interaction was done within the Lines model, keeping the fully ab initio treatment of magnetic anisotropy effects on individual cobalt fragments using a recently developed methodology. A good description of the susceptibility and magnetization was obtained for nearest-neighbor (J1) and next-nearest-neighbor (J2) exchange parameters (1.5 and 5.5 cm(-1), respectively). The strong ferromagnetic interaction between distant cobalt ions arises as a result of low electron-promotion energies in the exchange bridges containing Co(III) ions. The calculations showed a large value of the magnetization along the main magnetic axis (10.1 mu(B)), which is a combined effect of the ferromagnetic exchange interaction and negative magnetic anisotropy on

  8. The Design of a Device for the Generation of a Strong Magnetic Field in an Air Gap Using Permanent Magnets

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2017-01-01

    Roč. 22, č. 2 (2017), s. 250-256 ISSN 1226-1750 Institutional support: RVO:67985891 Keywords : magnet ic field * permanent magnet s * NdFeB magnet s * Halbach arrays Subject RIV: BM - Solid Matter Physics ; Magnet ism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.713, year: 2016

  9. The mean energy loss by neutrino with magnetic moment in strong magnetic field with consideration of positronium contribution to photon dispersion

    Science.gov (United States)

    Mosichkin, A. F.

    2017-11-01

    The process of radiative decay of the neutrino with a magnetic moment in a strong magnetic field with consideration of positronium influence on photon dispersion has been studied. Positronium contribution to the photon polarization operator induces significant modifications of the photon dispersion law and neutrino radiative decay amplitude. It has been shown that the mean energy loss of a neutrino with magnetic a moment significantly increases, when the positronium contribution to photon dispersion is taken into account.

  10. Behavior of Particle Depots in Molten Silicon During Float-Zone Growth in Strong Magnetic Fields

    Science.gov (United States)

    Jauss, T.; Croell, A.; SorgenFrei, T.; Azizi, M.; Reimann, C.; Friedrich, J.; Volz, M. P.

    2014-01-01

    Solar cells made from directionally solidified silicon cover 57% of the photovoltaic industry's market [1]. One major issue during directional solidification of silicon is the precipitation of foreign phase particles. These particles, mainly SiC and Si3N4, are precipitated from the dissolved crucible coating, which is made of silicon nitride, and the dissolution of carbon monoxide from the furnace atmosphere. Due to their hardness and size of several hundred micrometers, those particles can lead to severe problems during the wire sawing process for wafering the ingots. Additionally, SiC particles can act as a shunt, short circuiting the solar cell. Even if the particles are too small to disturb the wafering process, they can lead to a grit structure of silicon micro grains and serve as sources for dislocations. All of this lowers the yield of solar cells and reduces the performance of cells and modules. We studied the behaviour of SiC particle depots during float-zone growth under an oxide skin, and strong static magnetic fields. For high field strengths of 3T and above and an oxide layer on the sample surface, convection is sufficiently suppressed to create a diffusive like regime, with strongly dampened convection [2, 3]. To investigate the difference between atomically rough phase boundaries and facetted growth, samples with [100] and [111] orientation were processed.

  11. COMPRESSIBLE RELATIVISTIC MAGNETOHYDRODYNAMIC TURBULENCE IN MAGNETICALLY DOMINATED PLASMAS AND IMPLICATIONS FOR A STRONG-COUPLING REGIME

    Energy Technology Data Exchange (ETDEWEB)

    Takamoto, Makoto [Department of Earth and Planetary Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Lazarian, Alexandre, E-mail: mtakamoto@eps.s.u-tokyo.ac.jp, E-mail: alazarian@facstaff.wisc.edu [Department of Astronomy, University of Wisconsin, 475 North Charter Street, Madison, WI 53706 (United States)

    2016-11-10

    In this Letter, we report compressible mode effects on relativistic magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using three-dimensional numerical simulations. We decomposed fluctuations in the turbulence into 3 MHD modes (fast, slow, and Alfvén) following the procedure of mode decomposition in Cho and Lazarian, and analyzed their energy spectra and structure functions separately. We also analyzed the ratio of compressible mode to Alfvén mode energy with respect to its Mach number. We found the ratio of compressible mode increases not only with the Alfvén Mach number, but also with the background magnetization, which indicates a strong coupling between the fast and Alfvén modes. It also signifies the appearance of a new regime of RMHD turbulence in Poynting-dominated plasmas where the fast and Alfvén modes are strongly coupled and, unlike the non-relativistic MHD regime, cannot be treated separately. This finding will affect particle acceleration efficiency obtained by assuming Alfvénic critical-balance turbulence and can change the resulting photon spectra emitted by non-thermal electrons.

  12. Local Magnetism in Strongly Correlated Electron Systems with Orbital Degrees of Freedom

    Science.gov (United States)

    Ducatman, Samuel Charles

    The central aim of my research is to explain the connection between the macroscopic behavior and the microscopic physics of strongly correlated electron systems with orbital degrees of freedom through the use of effective models. My dissertation focuses on the sub-class of these materials where electrons appear to be localized by interactions, and magnetic ions have well measured magnetic moments. This suggests that we can capture the low-energy physics of the material by employing a minimal model featuring localized spins which interact with each other through exchange couplings. I describe Fe1+y Te and beta-Li2IrO3 with effective models primarily focusing on the spins of the magnetic ions, in this case Fe and Ir, respectively. The goal with both materials is to gain insight and make predictions for experimentalists. In chapter 2, I focus on Fe1+yTe. I describe why we believe the magnetic ground state of this material, with an observed Bragg peak at Q +/- pi/2, pi/2), can be described by a Heisenberg model with 1st, 2nd, and 3rd neighbor interactions. I present two possible ground states of this model in the small J1 limit, the bicollinear and plaquette states. In order to predict which ground state the model prefers, I calculate the spin wave spectrum with 1/S corrections, and I find the model naturally selects the "plaquette state." I give a brief description of the ways this result could be tested using experimental techniques such as polarized neutron scattering. In chapter 3, I extend the model used in chapter 2. This is necessary because the Heisenberg model we employed cannot explain why Fe1+yTe undergoes a phase transition as y is increased. We add an additional elements to our calculation; we assume that electrons in some of the Fe 3D orbitals have selectively localized while others remain itinerant. We write a new Hamiltonian, where localized moments acquire a new long-range RKKY-like interaction from interactions with the itinerant electrons. We are

  13. The contribution of Diamond Light Source to the study of strongly correlated electron systems and complex magnetic structures.

    Science.gov (United States)

    Radaelli, P G; Dhesi, S S

    2015-03-06

    We review some of the significant contributions to the field of strongly correlated materials and complex magnets, arising from experiments performed at the Diamond Light Source (Harwell Science and Innovation Campus, Didcot, UK) during the first few years of operation (2007-2014). We provide a comprehensive overview of Diamond research on topological insulators, multiferroics, complex oxides and magnetic nanostructures. Several experiments on ultrafast dynamics, magnetic imaging, photoemission electron microscopy, soft X-ray holography and resonant magnetic hard and soft X-ray scattering are described. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  14. Numerical simulations of a cylinder wake under a strong axial magnetic field

    Science.gov (United States)

    Dousset, Vincent; Pothérat, Alban

    2008-01-01

    We study the flow of a liquid metal in a square duct past a circular cylinder in a strong externally imposed magnetic field. In these conditions, the flow is quasi-two-dimensional, which allows us to model it using a two-dimensional (2D) model. We perform a parametric study by varying the two control parameters Re and Ha (Ha2 is the ratio of Lorentz to viscous forces) in the ranges [0…6000] and [0…2160], respectively. The flow is found to exhibit a sequence of four regimes. The first three regimes are similar to those of the non-magnetohydrodynamic (non-MHD) 2D circular wake, with transitions controlled by the friction parameter Re /Ha. The fourth one is characterized by vortices raising from boundary layer separations at the duct side walls, which strongly disturbs the Kármán vortex street. This provides the first explanation for the breakup of the 2D Kármán vortex street first observed experimentally by Frank, Barleon, and Müller [Phys. Fluids 13, 2287 (2001)]. We also show that, for high values of Ha (Ha⩾1120), the transition to the fourth regime occurs for Re ∝0.56Ha, and that it is accompanied by a sudden drop in the Strouhal number. In the first three regimes, we show that the drag coefficient and the length of the steady recirculation regions located behind the cylinder are controlled by the parameter Re /Ha4/5. Also, the free shear layer that separates the recirculation region from the free stream is similar to a free MHD parallel layer, with a thickness of the order of Ha-1/2 that is quite different to that of the non-MHD case, and therefore strongly influences the dynamics of this region. We also present one case at Re =3×104 and Ha =1120, where this layer undergoes an instability of the Kelvin-Helmholtz-type.

  15. Magnetic structure of RPdSn (R=Tb, Ho) single crystal compounds under strong magnetic field

    International Nuclear Information System (INIS)

    Andoh, Y.; Kurisu, M.; Nakamoto, G.; Tsutaoka, T.; Kawano, S.

    2003-01-01

    Rare earth compounds RTX, where R stands for rare earth elements, T for Ni, Pd or Rh, and X for Sn or Ge, crystallize to a rhombic ε-TiNiSi structure. Only rare earth elements R contribute to magnetic properties since T and X atoms are nonmagnetic. The competition between RKKY indirect interaction and large magnetic anisotropy generates many complicated magnetic phases. At a low temperature phase, complicated magnetisms such as meta-magnetism were observed in magnetization curves with many steps. In previous experiments dealing with RPdSn where R means Tb or Ho, some characteristics of magnetic properties of these compounds were deduced from magnetization measurements and neutron diffraction without external magnetic field. In this report, the change of magnetic scattering of neutron diffraction was studied under external magnetic fields in order to reveal the mechanism of the phase transformations of the compounds. The difference between TbPdSn and HoPdSn compounds was observed in magnetic field dependence of the wave vectors of the magnetic scattering. Two independent wave vectors in magnetic scattering existed in HoPdSn compound. (Y. Kazumata)

  16. The light-induced structuralization in magnetic fluids with negative Soret constant

    Energy Technology Data Exchange (ETDEWEB)

    Kopcansky, Peter [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Kosice (Slovakia); Hnatic, Michal [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Kosice (Slovakia)]. E-mail: hnatic@saske.sk; Repasan, Marian [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Kosice (Slovakia); Potocova, Ivana [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Kosice (Slovakia); Timko, Milan [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 043 53 Kosice (Slovakia); Turek, Ivan [Department of Physics, University of Zilina, Velky Diel, 010 26 Zilina (Slovakia); Stelina, Julius [Department of Physics, University of Zilina, Velky Diel, 010 26 Zilina (Slovakia); Musil, Ctibor [Department of Physics, University of Zilina, Velky Diel, 010 26 Zilina (Slovakia); Bracinik, Juraj [Department of Physics, University of Zilina, Velky Diel, 010 26 Zilina (Slovakia); Ayrjan, Edik [Laboratory of Information Technologies, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation); Vekas, Ladislau [Center for Fundamental and Advanced Technical Research, Romanian Academy, Blvd. Mihai Viteazul 24, 1900 Timisoara (Romania); Bica, Doina [Center for Fundamental and Advanced Technical Research, Romanian Academy, Blvd. Mihai Viteazul 24, 1900 Timisoara (Romania)

    2005-03-15

    The structuralization of the colloidal particles concentration in illuminated magnetic fluids with negative Soret constant was investigated. A theoretical explanation of the phenomenon, based on the study of the thermodiffusion process in colloidal fluids, was made. The development of the structuralization after the intensity of the illumination reaches some critical value was both simulated and observed experimentally.

  17. Magnetic ordering temperature of nanocrystalline Gd: enhancement of magnetic interactions via hydrogenation-induced "negative" pressure

    Czech Academy of Sciences Publication Activity Database

    Tereshina, Evgeniya; Khmelevskyi, S.; Politova, G.; Kaminskaya, T.; Drulis, H.; Tereshina, I. S.

    2016-01-01

    Roč. 6, Mar (2016), 1-7, č. článku 22553. ISSN 2045-2322 R&D Projects: GA ČR GA16-03593S Institutional support: RVO:68378271 Keywords : ferromagnetism * gadolinium * Curie temperature Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.259, year: 2016

  18. Magnetic resonance imaging of lumbar spine disc diseases. Frequency of false negatives

    International Nuclear Information System (INIS)

    Berthelot, J.M.; Maugars, Y.; Delecrin, Y.; Caillon, F.; Prost, A.

    1995-01-01

    Magnetic resonance imaging (MRI) has had an impressive impact on evaluation of degenerative diseases of the spine. Nevertheless, false negatives can occur on images involving lumbar discs. Degenerative disc diseases documented on discography and/or pathology examination of the discs can go unrecognized. Likewise sensitivity for the detection of protruding disc hernias is not totally satisfactory (20% false negatives). Finally, a magnetic resonance image visualizing displacement of the disc is not specific (10 to 15% false positives); images showing protrusion or hernia can be seen in 30% of asymptomatic patients. Although MRI gives slightly more information than other imaging techniques, false images do exist. Moreover, the usefulness of MRI to demonstrate disc disease in case of a negative CT-scan remains to be demonstrated. (authors). 26 refs

  19. Accurate and balanced anisotropic Gaussian type orbital basis sets for atoms in strong magnetic fields

    Science.gov (United States)

    Zhu, Wuming; Trickey, S. B.

    2017-12-01

    In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li+, Be+, and B+, in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B field.

  20. Accurate and balanced anisotropic Gaussian type orbital basis sets for atoms in strong magnetic fields.

    Science.gov (United States)

    Zhu, Wuming; Trickey, S B

    2017-12-28

    In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li + , Be + , and B + , in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B

  1. Electron cyclotron resonance heating by magnetic filter field in a negative hydrogen ion source

    Energy Technology Data Exchange (ETDEWEB)

    Kim, June Young, E-mail: beacoolguy@snu.ac.kr; Cho, Won-Hwi; Dang, Jeong-Jeung; Chung, Kyoung-Jae, E-mail: jkjlsh1@snu.ac.kr; Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2016-02-15

    The influence of magnetic filter field on plasma properties in the heating region has been investigated in a planar-type inductively coupled radio-frequency (RF) H{sup −} ion source. Besides filtering high energy electrons near the extraction region, the magnetic filter field is clearly observed to increase the electron temperature in the heating region at low pressure discharge. With increasing the operating pressure, enhancement of electron temperature in the heating region is reduced. The possibility of electron cyclotron resonance (ECR) heating in the heating region due to stray magnetic field generated by a filter magnet located at the extraction region is examined. It is found that ECR heating by RF wave field in the discharge region, where the strength of an axial magnetic field is approximately ∼4.8 G, can effectively heat low energy electrons. Depletion of low energy electrons in the electron energy distribution function measured at the heating region supports the occurrence of ECR heating. The present study suggests that addition of axial magnetic field as small as several G by an external electromagnet or permanent magnets can greatly increase the generation of highly ro-vibrationally excited hydrogen molecules in the heating region, thus improving the performance of H{sup −} ion generation in volume-produced negative hydrogen ion sources.

  2. SU-E-T-227: Could the Alpha/Beta Ratio Change in a Strong Magnetic Field?

    Energy Technology Data Exchange (ETDEWEB)

    Pang, G [Odette Cancer Centre, 2075 Bayview Avenue, Toronto M4N 3M5, Canada and Sunnybrook Research Institute and Departments of Radiation Oncology and Medical Biophysics, University of Toronto, Toronto (Canada)

    2015-06-15

    Purpose: Magnetic resonance imaging (MRI) is being integrated into radiotherapy delivery for MRI-guided radiotherapy. The presence of a strong magnetic field from a MRI machine during radiotherapy delivery presents a new challenge since the trajectories of electrons liberated by ionizing radiation in patients are strongly dependent on the applied magnetic field. The purpose of this work is to explore the potential effect of a strong magnetic field on the α/β ratio, an important radiobiological parameter in radiotherapy. Methods: Based on the theory of dual radiation action, the α/β ratio can be expressed by an integral of the product of two microdosimetry quantities γ(x) and t(x), where γ(x) is the probability that two energy transfers, a distance x apart, results in a lesion, and t(x) is the proximity function, which is the energy-weighted point-pair distribution of distances between energy transfer points in a track. The quantity t(x) depends on the applied magnetic field. An analytical approach has been used to derive a formula that can be used to calculate the α/β ratio in an extremely strong magnetic field. Results: The α/β ratio has been evaluated in the special case when the applied magnetic field approaches infinity, which gives the upper limit of the potential change of the α/β ratio due to the presence of a strong magnetic field. For V79 Chinese hamster cells it has been shown that the α/β ratio could be increased by 2.90 times for Pd-103, 2.97 times for I-125 and about 2.3 times for Co-60 sources when the applied magnetic field approaches infinity. Conclusion: It has been shown theoretically that the α/β ratio can change in a strong magnetic field, and there could be up to a nearly three-fold increase in the α/β ratio, depending on the strength of the applied magnetic field, the cell type and the radiation used.

  3. Influence of the configuration of the magnetic filter field on the discharge structure in the RF driven negative ion source prototype for fusion

    Science.gov (United States)

    Lishev, S.; Schiesko, L.; Wünderlich, D.; Fantz, U.

    2017-08-01

    The study provides results for the influence of the filter field topology on the plasma parameters in the RF prototype negative ion source for ITER NBI. A previously developed 2D fluid plasma model of the prototype source was extended towards accounting for the particles and energy losses along the magnetic field lines and the presence of a magnetic field in the driver which is the case at the BATMAN and ELISE test-beds. The effect of the magnetic field in the driver is shown for the magnetic field configuration of the prototype source (i.e. a magnetic field produced by an external magnet frame) by comparison of plasma parameters without and with the magnetic field in the driver and for different axial positions of the filter. Since the ELISE-like magnetic field (i.e. a magnetic field produced by a current flowing through the plasma grid) is a new feature planned to be installed at the BATMAN test-bed, its effect on the discharge structure was studied for different strengths of the magnetic field. The obtained results show for both configurations of the magnetic filter the same main features in the patterns of the plasma parameters in the expansion chamber: a strong axial drop of the electron temperature and the formation of a groove accompanied with accumulation of electrons in front of the plasma grid. The presence of a magnetic field in the driver has a local impact on the plasma parameters: the formation of a second groove of the electron temperature in the case of BATMAN (due to the reversed direction of the filter field in the driver) and a strong asymmetry of the electron density. Accounting for the additional losses in the third dimension suppresses the drifts across the magnetic field and, thus, the variations of the electron density in the expansion chamber are less pronounced.

  4. The D sup - centre in a quantum well in the presence of parallel electric and strong magnetic fields

    CERN Document Server

    Monozon, B S

    2003-01-01

    An analytical approach to the problem of a negatively charged donor in an infinitely deep quantum well (QW) in the presence of parallel electric and strong magnetic external fields both directed perpendicular to the heteroplanes is developed. The double adiabatic approximation is employed. The dependences of the binding energy on the field strengths, the width of the well and the position of the impurity within the well are derived in explicit form. The effect of the inversion of the electric field is investigated. It is shown that the combined potential acting on the 'outer' electron resembles that of a double QW. When the levels associated with the two effective QWs anticross, a resonant structure arises. The explicit dependence of the resonant splitting on the width of the QW, the strength of the electric field and the position of the impurity are obtained. Using the parameters associated with the GaAs QW, estimates of the inversion shift of the binding energy and the frequency of the emitted resonant radi...

  5. Biological effects of electromagnetic fields and recently updated safety guidelines for strong static magnetic fields

    International Nuclear Information System (INIS)

    Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo

    2011-01-01

    Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields. (author)

  6. Biological effects of electromagnetic fields and recently updated safety guidelines for strong static magnetic fields.

    Science.gov (United States)

    Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo

    2011-01-01

    Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields.

  7. Concepts relating magnetic interactions, intertwined electronic orders, and strongly correlated superconductivity

    Science.gov (United States)

    Davis, J. C. Séamus; Lee, Dung-Hai

    2013-01-01

    Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron–electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron–electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron–electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs. PMID:24114268

  8. Orientation of glutaraldehyde-fixed erythrocytes in strong static magnetic fields.

    Science.gov (United States)

    Higashi, T; Sagawa, S; Ashida, N; Takeuchi, T

    1996-01-01

    In a uniform static magnetic field up to 8 Telsa, glutaraldehyde-fixed erythrocytes showed an orientation in which their disk plane was perpendicular to the magnetic field. The paramagnetism of membrane-bound hemoglobin was through to contribute significantly to this orientation. The observation of magnetic orientation is directed toward understanding the fundamental microstructural aspects of the erythrocyte.

  9. A Comparison of Different Engineering Models for Computation of Lightning Magnetic Field of Negative First Strokes

    Directory of Open Access Journals (Sweden)

    V. Javor

    2012-11-01

    Full Text Available A comparison of different engineering models results for a lightning magnetic field of negative first strokes is presented in this paper. A new function for representing double-peaked channel-base current is used for lightning stroke modeling. This function includes the initial and subsidiary peak in a current waveform. For experimentally measured currents, a magnetic field is calculated for the three engineering models: transmission line (TL model, TL model with linear decay (MTLL, and TL model with exponential decay (MTLE.

  10. MULTI-WAVELENGTH STUDY OF A DELTA-SPOT. I. A REGION OF VERY STRONG, HORIZONTAL MAGNETIC FIELD

    International Nuclear Information System (INIS)

    Jaeggli, S. A.

    2016-01-01

    Active region NOAA 11035 appeared in 2009 December, early in the new solar activity cycle. This region achieved a delta sunspot (δ spot) configuration when parasitic flux emerged near the rotationally leading magnetic polarity and traveled through the penumbra of the largest sunspot in the group. Both visible and infrared imaging spectropolarimetry of the magnetically sensitive Fe i line pairs at 6302 and 15650 Å show large Zeeman splitting in the penumbra between the parasitic umbra and the main sunspot umbra. The polarized Stokes spectra in the strongest field region display anomalous profiles, and strong blueshifts are seen in an adjacent region. Analysis of the profiles is carried out using a Milne–Eddington inversion code capable of fitting either a single magnetic component with stray light or two independent magnetic components to verify the field strength. The inversion results show that the anomalous profiles cannot be produced by the combination of two profiles with moderate magnetic fields. The largest field strengths are 3500–3800 G in close proximity to blueshifts as strong as 3.8 km s −1 . The strong, nearly horizontal magnetic field seen near the polarity inversion line in this region is difficult to understand in the context of a standard model of sunspot magnetohydrostatic equilibrium

  11. MULTI-WAVELENGTH STUDY OF A DELTA-SPOT. I. A REGION OF VERY STRONG, HORIZONTAL MAGNETIC FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Jaeggli, S. A., E-mail: sarah.jaeggli@nasa.gov [NASA Goddard Space Flight Center, Solar Physics Laboratory, Code 671, Greenbelt, MD 20771 (United States)

    2016-02-10

    Active region NOAA 11035 appeared in 2009 December, early in the new solar activity cycle. This region achieved a delta sunspot (δ spot) configuration when parasitic flux emerged near the rotationally leading magnetic polarity and traveled through the penumbra of the largest sunspot in the group. Both visible and infrared imaging spectropolarimetry of the magnetically sensitive Fe i line pairs at 6302 and 15650 Å show large Zeeman splitting in the penumbra between the parasitic umbra and the main sunspot umbra. The polarized Stokes spectra in the strongest field region display anomalous profiles, and strong blueshifts are seen in an adjacent region. Analysis of the profiles is carried out using a Milne–Eddington inversion code capable of fitting either a single magnetic component with stray light or two independent magnetic components to verify the field strength. The inversion results show that the anomalous profiles cannot be produced by the combination of two profiles with moderate magnetic fields. The largest field strengths are 3500–3800 G in close proximity to blueshifts as strong as 3.8 km s{sup −1}. The strong, nearly horizontal magnetic field seen near the polarity inversion line in this region is difficult to understand in the context of a standard model of sunspot magnetohydrostatic equilibrium.

  12. Magnetic properties of the strongly correlated chain antiferromagnet KTb(WO4)2

    International Nuclear Information System (INIS)

    Khatsko, E.; Loginov, A.; Cherny, A.; Rykova, A.

    2006-01-01

    The susceptibility and magnetization of a single crystal of KTb(WO 4 ) 2 has been measured in the temperature range 0.5-80 K in magnetic fields up to 6 T. It is shown that KTb(WO 4 ) 2 is an Ising magnet with only one component of the magnetic moment. The three-dimensional phase transition to the antiferromagnetically ordered state has been found below 0.7 K. This transition can be described in the molecular field two-level approximation. The principal exchange constant has been estimated. By using experimental data the magnetic structure of KTb(WO 4 ) 2 is proposed

  13. Behavior of Particle Depots in Molten Silicon During Float-Zone Growth in Strong Static Magnetic Fields

    Science.gov (United States)

    Jauss, T.; SorgenFrei, T.; Croell, A.; Azizi, M.; Reimann, C.; Friedrich, J.; Volz, M. P.

    2014-01-01

    In the photovoltaics industry, the largest market share is represented by solar cells made from multicrystalline silicon, which is grown by directional solidification. During the growth process, the silicon melt is in contact with the silicon nitride coated crucible walls and the furnace atmosphere which contains carbon monoxide. The dissolution of the crucible coating, the carbon bearing gas, and the carbon already present in the feedstock, lead to the precipitation of silicon carbide, and silicon nitride, at later stages of the growth process. The precipitation of Si3N4 and SiC particles of up to several hundred micrometers in diameter leads to severe problems during the wire sawing process for wafering the ingots. Furthermore the growth of the silicon grains can be negatively influenced by the presence of particles, which act as nucleation sources and lead to a grit structure of small grains and are sources for dislocations. If doped with Nitrogen from the dissolved crucible coating, SiC is a semi conductive material, and can act as a shunt, short circuiting parts of the solar cell. For these reasons, the incorporation of such particles needs to be avoided. In this contribution we performed model experiments in which the transport of intentionally added SiC particles and their interaction with the solid-liquid interface during float zone growth of silicon in strong steady magnetic fields was investigated. SiC particles of 7µm and 60µm size are placed in single crystal silicon [100] and [111] rods of 8mm diameter. This is achieved by drilling a hole of 2mm diameter, filling in the particles and closing the hole by melting the surface of the rod until a film of silicon covers the hole. The samples are processed under a vacuum of 1x10(exp -5) mbar or better, to prevent gas inclusions. An oxide layer to suppress Marangoni convection is applied by wet oxidation. Experiments without and with static magnetic field are carried out to investigate the influence of melt

  14. Comparative studies of density-functional approximations for light atoms in strong magnetic fields

    Science.gov (United States)

    Zhu, Wuming; Zhang, Liang; Trickey, S. B.

    2014-08-01

    For a wide range of magnetic fields, 0≤B≤2000 a.u., we present a systematic comparative study of the performance of different types of density-functional approximations in light atoms (2≤Z≤6). Local, generalized-gradient approximation (GGA; semilocal), and meta-GGA ground-state exchange-correlation (xc) functionals are compared on an equal footing with exact-exchange, Hartree-Fock (HF), and current-density-functional-theory (CDFT) approximations. Comparison also is made with published quantum Monte Carlo data. Though all approximations give qualitatively reasonable results, the exchange energies from local and GGA functionals are too negative for large B. Results from the Perdew-Burke-Ernzerhof ground-state GGA and Tao-Perdew-Staroverov-Scuseria (TPSS) ground-state meta-GGA functionals are very close. Because of confinement, self-interaction error in such functionals is more severe at large B than at B =0, hence self-interaction correction is crucial. Exact exchange combined with the TPSS correlation functional results in a self-interaction-free (xc) functional, from which we obtain atomic energies of comparable accuracy to those from correlated wave-function methods. Specifically for the B and C atoms, we provide beyond-HF energies in a wide range of B fields. Fully self-consistent CDFT calculations were done with the Vignale-Rasolt-Geldart (VRG) functional in conjunction with the PW92 xc functional. Current effects turn out to be small, and the vorticity variable in the VRG functional diverges in some low-density regions. This part of the study suggests that nonlocal, self-interaction-free functionals may be better than local approximations as a starting point for CDFT functional construction and that some basic variable other than the vorticity could be helpful in making CDFT calculations practical.

  15. Negative magnetoresistance in perpendicular of the superlattices axis weak magnetic field at scattering of impurity ions

    International Nuclear Information System (INIS)

    Askerov, B. M.; Figarova, R.; Guseynov, G.I.

    2012-01-01

    Full Text : The transverse magnetoresistance in superlattices with the cosine dispersion law of conduction electrons in a case, when a weak magnetic field in plane of layer at scattering of the charge carriers of impurity ions has been studied. It has been shown that in a quasi-two-dimensional case the magnetoresistance was positive, while in a quasi-three-dimensional case can become negative depending of a degree of mini-band filling. Such behavior of magnetoresistance, apparently, has been related to presence in a mini-band of region with the negative effective mass

  16. Tunneling Negative Magnetoresistance via δ Doping in a Graphene-Based Magnetic Tunnel Junction

    International Nuclear Information System (INIS)

    Yuan Jian-Hui; Chen Ni; Mo Hua; Zhang Yan; Zhang Zhi-Hai

    2016-01-01

    We investigate the tunneling magnetoresistance via δ doping in a graphene-based magnetic tunnel junction in detail. It is found that the transmission probability and the conductance oscillates with the position and the aptitude of the δ doping. Also, both the transmission probability and the conductance at the parallel configuration are suppressed by the magnetic field more obviously than that at the antiparallel configuration, which implies a large negative magnetoresistance for this device. The results show that the negative magnetoresistance of over 300% at B = 1.0 T is observed by choosing suitable doped parameters, and the temperature plays an important role in the magnetoresistance. Thus it is possible to open a way to effectively manipulate the magnetoresistance devices, and to make a type of magnetoresistance device by controlling the structural parameter of the δ doping. (paper)

  17. Strongly magnetic soil developed on a non-magnetic rock basement: A case study from NW Bulgaria

    Czech Academy of Sciences Publication Activity Database

    Grison, Hana; Petrovský, Eduard; Jordanova, N.; Kapička, Aleš

    2011-01-01

    Roč. 55, č. 4 (2011), s. 697-716 ISSN 0039-3169 R&D Projects: GA AV ČR(CZ) KJB300120604 Institutional research plan: CEZ:AV0Z30120515 Keywords : magnetic susceptibility * magnetite * soil * pollution * climate * limestone Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.700, year: 2011

  18. Light-induced changes of cubic and uniaxial magnetic aniosotropy in a magnet doped by strongly anisotropic ions

    Czech Academy of Sciences Publication Activity Database

    Zaytseva, I.; Stupakiewicz, A.; Maziewski, A.; Zablotskyy, Vitaliy A.

    254-255, - (2003), s. 118-120 ISSN 0304-8853. [Soft Magnetic Material Conference ( SMM 15). Bilbao, 05.09.2001-07.09.2001] Institutional research plan: CEZ:AV0Z1010914 Keywords : photomagnetic effects * light-induced anisotropy * garnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.910, year: 2003

  19. Performance evaluation of a permanent ring magnet based helicon plasma source for negative ion source research

    Science.gov (United States)

    Pandey, Arun; Bandyopadhyay, M.; Sudhir, Dass; Chakraborty, A.

    2017-10-01

    Helicon wave heated plasmas are much more efficient in terms of ionization per unit power consumed. A permanent magnet based compact helicon wave heated plasma source is developed in the Institute for Plasma Research, after carefully optimizing the geometry, the frequency of the RF power, and the magnetic field conditions. The HELicon Experiment for Negative ion-I source is the single driver helicon plasma source that is being studied for the development of a large sized, multi-driver negative hydrogen ion source. In this paper, the details about the single driver machine and the results from the characterization of the device are presented. A parametric study at different pressures and magnetic field values using a 13.56 MHz RF source has been carried out in argon plasma, as an initial step towards source characterization. A theoretical model is also presented for the particle and power balance in the plasma. The ambipolar diffusion process taking place in a magnetized helicon plasma is also discussed.

  20. Molecular quantum magnetism with strong spin-orbit coupling in inorganic solid Ba3Yb2Zn5O11

    Science.gov (United States)

    Park, Sang-Youn; Ji, Sungdae; Park, Jae-Hoon; Do, Seunghwan; Choi, Kwang-Yong; Jang, Dongjin; Schmidt, Burkhard; Brando, Manuel; Butch, Nicholas

    The molecular magnet, assembly of finite number of spins which are isolated from environment, is a model system to study the quantum information process such as the qubit or spintronic devices. In past decades, the molecular magnet has been mostly realized in organic material, however, it has difficulty synthesizing materials or controlling their properties, meanwhile tremendous endeavors to search inorganic molecular magnet are continuing. Here, we propose Ba3Yb2Zn5O11 as a candidate of inorganic molecular magnet. This material consists of an alternating 3D-array of small and large tetrahedron containing antiferromagnetically coupled four pseudospin-1/2 Yb ions, and magnetic properties are described by an isolated tetrahedron without long-range magnetic ordering. Inelastic neutron scattering measurement with external magnetic field reveals that extraordinarily huge Dzyaloshinsky-Moriya (DM) interaction originating from strong spin-orbit coupling in Yb isospin is the key to explain energy level of tetrahedron in addition to Heisenberg exchange interaction and Zeeman effect. Magnetization measurement shows the Landau-Zener transition between avoided crossing levels caused by DM interaction.

  1. Method for Transformation of Weakly Magnetic Minerals (Hematite, Goethite into Strongly Magnetic Mineral (Magnetite to Improve the Efficiency of Technologies for Oxidized Iron Ores Benefication

    Directory of Open Access Journals (Sweden)

    Ponomarenko, O.

    2015-03-01

    Full Text Available A new method for relatively simple transformation of weakly magnetic minerals (goethite (α-FeOOH and hematite (α-Fe2O3 into strongly magnetic mineral (magnetite (Fe3O4 was developed. It was shown, that transformation of structure and magnetic characteristics of go ethite and hematite are realized in the presence of starch at relatively low temperatures (in the range of 300—600 °С. Obtained results open up new possibilities for development of effective technologies for oxidized iron ore beneficiation.

  2. The sharp-front magnetic diffusion wave of a strong magnetic field diffusing into a solid metal

    Science.gov (United States)

    Xiao, Bo; Gu, Zhuo-Wei; Kan, Ming-Xian; Wang, Gang-Hua; Zhao, Jian-Heng; Computational Physics Team

    2016-10-01

    When a mega-gauss magnetic field diffuses into a solid metal, the Joule heat would rise rapidly the temperature of the metal, and the rise of temperature leads to an increase of the metal's resistance, which in turn accelerates the magnetic field diffusion. Those positive feedbacks acting iteratively would lead to an interesting sharp-front magnetic diffusion wave. By assuming that the metal's resistance has an abrupt change from a small value ηS to larger value ηL at some critical temperature Tc, the sharp-front magnetic diffusion wave can be solved analytically. The conditions for the emerging of the sharp-front magnetic diffusion wave are B0 >Bc , ηL /ηS >> 1 , and ηL/ηSB0/-Bc Bc >> 1 , where Bc =√{ 2μ0Jc } , B0 is the vacuum magnetic field strength, and Jc is the critical Joule heat density. The wave-front velocity of the diffusion wave is Vc =ηL/μ0B0/-Bc Bc1/xc , where xc is the depth the wave have propagated in the metal. In this presentation we would like to discuss the derivation of the formulas and its impact to magnetically driven experiments. The work is supported by the Foundation of China Academy of Engineering Physics (No. 2015B0201023).

  3. STRONG MAGNETIC-X-RAY DICHROISM IN 2P ABSORPTION-SPECTRA OF 3D TRANSITION-METAL IONS

    NARCIS (Netherlands)

    VANDERLAAN, G; THOLE, BT

    1991-01-01

    From atomic calculations in crystal-field symmetry we find a very strong circular and linear dichroism in the 2p x-ray absorption edges of magnetically ordered 3d transition-metal ions. The spectral shape changes drastically with the character of the ground state, which is determined by the presence

  4. Study of muon triggers and momentum reconstruction in a strong magnetic field for a muon detector at LHC

    CERN Document Server

    Della Negra, Michel; Eggert, Karsten; Hervé, A; Wittgenstein, F; Karimäki, V; Kinnunen, Ritva; Pimiä, M; Tuominiemi, Jorma; Dau, D; Ferrando, A; Torrente-Lujan, E; Bettini, A; Centro, Sandro; Martinelli, R; Meneguzzo, Anna Teresa; Zotto, P L; Bacci, Cesare; Ceradini, F; Ciapetti, G; Lacava, F; Nisati, A; Petrolo, E; Pontecorvo, L; Veneziano, Stefano; Zanello, L; Cardarelli, R; Di Ciaccio, Anna; Santonico, R; Cline, D; Lazic, S; Mohammadi, M; Park, J; Szoncsó, F; Walzel, G; Wulz, Claudia Elisabeth; CERN. Geneva. Detector Research and Development Committee

    1990-01-01

    We propose to construct a small fraction of a muon detector in a strong magnetic field, for possible use in an LHC experiment, and to test it in a beam containing hadrons and muons. Properties of muons from hadron decays and of hadron punch-through, i.e. angle, momentum and timing distributions of the outgoing particles, will be measured for various absorber thicknesses, including the effect of strong magnetization of the absorber. The efficiency of different muon triggers and the rejection against hadron punch-through and decay muons will be studied. Reconstruction of muons and their momentum measurement in magnetized iron will be investigated, including the effect of catastrophic energy losses of high momentum muons. The performance of resistive plate chambers (RPC) as fast trigger hodoscopes will be studied.

  5. Aversive responses of captive sandbar sharks Carcharhinus plumbeus to strong magnetic fields

    NARCIS (Netherlands)

    Siegenthaler, A.; Niemantsverdriet, P.R.W.; Laterveer, M.; Heitkönig, I.M.A.

    2016-01-01

    This experimental study focused on the possible deterrent effect of permanent magnets on adult sandbar sharks Carcharhinus plumbeus. Results showed that the presence of a magnetic field significantly reduced the number of approaches of conditioned C. plumbeus towards a target indicating that

  6. Effect of angular momentum alignment and strong magnetic fields on the formation of protostellar discs

    Science.gov (United States)

    Gray, William J.; McKee, Christopher F.; Klein, Richard I.

    2018-01-01

    Star-forming molecular clouds are observed to be both highly magnetized and turbulent. Consequently, the formation of protostellar discs is largely dependent on the complex interaction between gravity, magnetic fields, and turbulence. Studies of non-turbulent protostellar disc formation with realistic magnetic fields have shown that these fields are efficient in removing angular momentum from the forming discs, preventing their formation. However, once turbulence is included, discs can form in even highly magnetized clouds, although the precise mechanism remains uncertain. Here, we present several high-resolution simulations of turbulent, realistically magnetized, high-mass molecular clouds with both aligned and random turbulence to study the role that turbulence, misalignment, and magnetic fields have on the formation of protostellar discs. We find that when the turbulence is artificially aligned so that the angular momentum is parallel to the initial uniform field, no rotationally supported discs are formed, regardless of the initial turbulent energy. We conclude that turbulence and the associated misalignment between the angular momentum and the magnetic field are crucial in the formation of protostellar discs in the presence of realistic magnetic fields.

  7. A Solar Eruption from a Weak Magnetic Field Region with Relatively Strong Geo-Effectiveness

    Science.gov (United States)

    Wang, R.

    2017-12-01

    A moderate flare eruption giving rise to a series of geo-effectiveness on 2015 November 4 caught our attentions, which originated from a relatively weak magnetic field region. The associated characteristics near the Earth are presented, which indicates that the southward magnetic field in the sheath and the ICME induced a geomagnetic storm sequence with a Dst global minimum of 90 nT. The ICME is indicated to have a small inclination angle by using a Grad-Shafranov technique, and corresponds to the flux rope (FR) structure horizontally lying on the solar surface. A small-scale magnetic cancelling feature was detected which is beneath the FR and is co-aligned with the Atmospheric Imaging Assembly (AIA) EUV brightening prior to the eruption. Various magnetic features for space-weather forecasting are computed by using a data product from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) called Space-weather HMI Active Region Patches (SHARPs), which help us identify the changes of the photospheric magnetic fields during the magnetic cancellation process and prove that the magnetic reconnection associated with the flux cancellation is driven by the magnetic shearing motion on the photosphere. An analysis on the distributions at different heights of decay index is carried out. Combining with a filament height estimation method, the configurations of the FR is identified and a decay index critical value n = 1 is considered to be more appropriate for such a weak magnetic field region. Through a comprehensive analysis to the trigger mechanisms and conditions of the eruption, a clearer scenario of a CME from a relatively weak region is presented.

  8. Spin excitations in systems with hopping electron transport and strong position disorder in a large magnetic field

    Science.gov (United States)

    Shumilin, A. V.

    2016-10-01

    We discuss the spin excitations in systems with hopping electron conduction and strong position disorder. We focus on the problem in a strong magnetic field when the spin Hamiltonian can be reduced to the effective single-particle Hamiltonian and treated with conventional numerical technics. It is shown that in a 3D system with Heisenberg exchange interaction the spin excitations have a delocalized part of the spectrum even in the limit of strong disorder, thus leading to the possibility of the coherent spin transport. The spin transport provided by the delocalized excitations can be described by a diffusion coefficient. Non-homogenous magnetic fields lead to the Anderson localization of spin excitations while anisotropy of the exchange interaction results in the Lifshitz localization of excitations. We discuss the possible effect of the additional exchange-driven spin diffusion on the organic spin-valve devices.

  9. Strong compression of a magnetic field with a laser-accelerated foil.

    Science.gov (United States)

    Yoneda, Hitoki; Namiki, Tomonori; Nishida, Akinori; Kodama, Ryosuke; Sakawa, Youichi; Kuramitsu, Yasuhiro; Morita, Taichi; Nishio, Kento; Ide, Takao

    2012-09-21

    We demonstrate the generation of high magnetic fields for condensed matter research using a high-power laser system. A cavity in which a seed magnetic field is applied is compressed by a kJ ns laser pulse. The time history of the compressed magnetic field is monitored by observing the Faraday effect rotation of polarization of a probe pulse in a glass fiber. To maintain a low-temperature condition in the final high-field region, we put a high-resistance foil around the final compression area. If we assume the length of the compression region is equal to the laser spot size, a magnetic field of more than 800 T is observed by Faraday rotation. Because of the large mass of the compression foil, this high magnetic field is sustained during almost 2 ns. During compression, a rarefaction wave from the backside of the accelerated foil and expanding material from the inner protection foil affect the magnetic field compression history, but the final compressed magnetic field strength agrees with the ratio between the initial sample area and the compressed cavity area.

  10. Magnetic-field dependence of strongly anisotropic spin reorientation transition in NdFeO3: a terahertz study.

    Science.gov (United States)

    Jiang, Junjie; Song, Gaibei; Wang, Dongyang; Jin, Zuanming; Tian, Zhen; Lin, Xian; Han, Jiaguang; Ma, Guohong; Cao, Shixun; Cheng, Zhenxiang

    2016-03-23

    One of the biggest challenges in spintronics is finding how to switch the magnetization of a material. One way of the spin switching is the spin reorientation transition (SRT), a switching of macroscopic magnetization rotated by 90°. The macroscopic magnetization in a NdFeO3 single crystal rotates from Γ4 to Γ2 via Γ24 as the temperature is decreased from 170 to 100 K, while it can be switched back to Γ4 again by increasing the temperature. However, the precise roles of the magnetic-field induced SRT are still unclear. By using terahertz time-domain spectroscopy (THz-TDS), here, we show that the magnetic-field induced SRT between Γ4 and Γ2 is strongly anisotropic, depending on the direction of the applied magnetic field. Our experimental results are well interpreted by the anisotropy of rare-earth Nd(3+) ion. Furthermore, we find that the critical magnetic-field required for SRT can be modified by changing the temperature. Our study suggests that the anisotropic SRT in NdFeO3 single crystal provides a platform to facilitate the potential applications in robust spin memory devices.

  11. Electronic bond structure of the H2+ ion in a strong magnetic field: A study of the parallel configuration

    International Nuclear Information System (INIS)

    Kappes, U.; Schmelcher, P.

    1995-01-01

    A large number of magnetically dressed states of the hydrogen molecular ion for parallel internuclear and magnetic field axes are investigated. The numerical calculations of the molecular states and potential-energy curves in the fixed-nuclei approximation are based on a recently established and optimized atomic orbital basis set. We study electronic states within the range 0≤|m|≤10 of magnetic quantum numbers and for several field strengths. In particular, we also investigate many excited states within a subspace for fixed magnetic quantum number and parity. In order to understand the influence of the magnetic field on theof excited molecular states, we perform a detailed comparison of the electronic probability distributions and potential-energy curves in the field-free space with those in the presence of a magnetic field. As a major result we observe the existence of two different classes of strongly bound, i.e., stable, magnetically dressed states whose corresponding counterparts in the field-free space exhibit purely repulsive potential-energy curves, i.e., are unstable. Corrections which are going beyond the fixed-nuclei approach, i.e., the coupling of the center of mass to the electronic motion, as well as the mass corrections are investigated in order to ensure the physical validity of our results

  12. Influence of calculation error of total field anomaly in strongly magnetic environments

    Science.gov (United States)

    Yuan, Xiaoyu; Yao, Changli; Zheng, Yuanman; Li, Zelin

    2016-04-01

    An assumption made in many magnetic interpretation techniques is that ΔTact (total field anomaly - the measurement given by total field magnetometers, after we remove the main geomagnetic field, T0) can be approximated mathematically by ΔTpro (the projection of anomalous field vector in the direction of the earth's normal field). In order to meet the demand for high-precision processing of magnetic prospecting, the approximate error E between ΔTact and ΔTpro is studied in this research. Generally speaking, the error E is extremely small when anomalies not greater than about 0.2T0. However, the errorE may be large in highly magnetic environments. This leads to significant effects on subsequent quantitative inference. Therefore, we investigate the error E through numerical experiments of high-susceptibility bodies. A systematic error analysis was made by using a 2-D elliptic cylinder model. Error analysis show that the magnitude of ΔTact is usually larger than that of ΔTpro. This imply that a theoretical anomaly computed without accounting for the error E overestimate the anomaly associated with the body. It is demonstrated through numerical experiments that the error E is obvious and should not be ignored. It is also shown that the curves of ΔTpro and the error E had a certain symmetry when the directions of magnetization and geomagnetic field changed. To be more specific, the Emax (the maximum of the error E) appeared above the center of the magnetic body when the magnetic parameters are determined. Some other characteristics about the error Eare discovered. For instance, the curve of Emax with respect to the latitude was symmetrical on both sides of magnetic equator, and the extremum of the Emax can always be found in the mid-latitudes, and so on. It is also demonstrated that the error Ehas great influence on magnetic processing transformation and inversion results. It is conclude that when the bodies have highly magnetic susceptibilities, the error E can

  13. Shannon entropy as an indicator of atomic avoided crossings in strong parallel magnetic and electric fields.

    Science.gov (United States)

    González-Férez, R; Dehesa, J S

    2003-09-12

    Avoided crossings are the most distinctive atomic spectroscopic features in the presence of magnetic and electric fields. We point out the role of Shannon's information entropy as an indicator or predictor of these phenomena by studying the dynamics of some excited states of hydrogen in the presence of parallel magnetic and electric fields. Moreover, in addition to the well-known energy level repulsion, it is found that Shannon's entropy manifests the informational exchange of the involved states as the magnetic field strength is varied across the narrow region where an avoided crossing occurs.

  14. The role of mental imagery in depression: Negative mental imagery induces strong implicit and explicit affect in depression

    Directory of Open Access Journals (Sweden)

    Stefanie Maria Görgen

    2015-07-01

    Full Text Available Mental imagery, seeing with the mind’s eyes, can induce stronger positive as well as negative affect compared to verbal processing. Given this emotion-amplifying effect, it appears likely that mental images play an important role in affective disorders. According to the subcomponents model of depression, depressed mood is maintained by both negative imagery (which amplifies negative mood and less efficient positive imagery processes. Empirical research on the link between mental imagery and affect in clinical depression, however, is still sparse. This study aimed at testing the role of mental imagery in depression, using a modified version of the Affect Misattribution Procedure (AMP and the Self-Assessment Manikin (SAM to assess implicit (AMP and explicit (SAM affect elicited by mental images, pictures, and verbal processing in clinically depressed participants (n = 32 compared to healthy controls (n = 32. In individuals with a depressive disorder, compared to healthy controls, negative mental images induced stronger negative affect in the explicit as well as implicit measure. Negative mental imagery did not, however, elicit greater increases in explicitly and implicitly assessed negative affect compared to other processing modalities (verbal processing, pictures in the depressed group. Additionally, a positive imagery deficit in depression was observed in the explicit measure. Interestingly, the two groups did not differ in implicitly assessed affect after positive imagery, indicating that depressed individuals might benefit from positive imagery on an implicit or automatic level. Overall, our findings suggest that mental imagery also plays an important role in depression and confirm the potential of novel treatment approaches for depression such as the promotion of positive imagery.

  15. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412

    DEFF Research Database (Denmark)

    Järvinen, S. P.; Hubrig, S.; Schöller, M.

    2016-01-01

    of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability...... that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous...... values determined in previous low-resolution FORS 2 measurements, where hydrogen Balmer lines are the main contributors to the magnetic field measurements, indicating the presence of concentration of the studied iron-peak elements in the region of the magnetic equator. Further, we discuss the potential...

  16. High-latitude ionospheric convection during strong interplanetary magnetic field B-y

    DEFF Research Database (Denmark)

    Huang, C.S.; Sofko, G.J.; Murr, D.

    1999-01-01

    . The interplanetary magnetic field (IMF) conditions corresponding to the occurrence of the ionospheric convection were B-x approximate to 1 nT, B-y approximate to 10 nT, and B-z ...An unusual high-latitude ionospheric pattern was observed on March 23, 1995. ionospheric convection appeared as clockwise merging convection cell focused at 84 degrees magnetic latitude around 1200 MLT. No signature of the viscous convection cell in the afternoon sector was observed...

  17. H2+ molecule in strong magnetic fields, studied by the method of linear combinations of orbitals

    International Nuclear Information System (INIS)

    de Melo, L.C.; Das, T.K.; Ferreira, R.C.; Miranda, L.C.M.; Brandi, H.S.

    1978-01-01

    We have studied the ground state of the H 2 + molecular ion in the presence of a homogeneous magnetic field, basing this study on a linear combination of atomic orbitals obtained from the hydrogen atom in a magnetic field. The calculations have shown that this scheme is adequate to describe the binding energy of the molecule at field strengths up to approximately 10 10 G

  18. Strong geomagnetic activity forecast by neural networks under dominant southern orientation of the interplanetary magnetic field

    Czech Academy of Sciences Publication Activity Database

    Valach, F.; Bochníček, Josef; Hejda, Pavel; Revallo, M.

    2014-01-01

    Roč. 53, č. 4 (2014), s. 589-598 ISSN 0273-1177 R&D Projects: GA AV ČR(CZ) IAA300120608; GA MŠk OC09070 Institutional support: RVO:67985530 Keywords : geomagnetic activity * interplanetary magnetic field * artificial neural network * ejection of coronal mass * X-ray flares Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.358, year: 2014

  19. Investigation of thin manganite films at strong pulsed electric and magnetic fields

    OpenAIRE

    Cimmperman, Piotras

    2006-01-01

    The main aim of this work was to investigate electrical conductivity of La-Ca(Sr)-MnO thin films at high pulsed electric and magnetic fields and to clear up the possibilities to use these materials for high pulsed magnetic field sensor and fault current limiter applications. The dissertation consists of the preface, six chapters, summary and main conclusions, references, list of publications and abstract (in Lithuanian). The main objectives of the work, scientific novelty, goals, valida...

  20. The Creation of a Strong Magnetic Field by Means of Large Magnetic Blocks from NdFeB Magnets in Opposing Linear Halbach Arrays

    Czech Academy of Sciences Publication Activity Database

    Žežulka, Václav; Straka, Pavel

    2016-01-01

    Roč. 21, č. 3 (2016), 364-373 ISSN 1226-1750 Institutional support: RVO:67985891 Keywords : magnetic field * permanent magnets * NdFeB magnets * Halbach Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.713, year: 2016 http://komag.org/journal/

  1. Strong and Weak Readings in the Domain of Worlds: A Negative Polar Modal and Children's Scope Assignment.

    Science.gov (United States)

    Koring, Loes; Meroni, Luisa; Moscati, Vincenzo

    2018-03-22

    This study investigates children's interpretation of sentences with two logical operators: Dutch universal modal hoeven and negation (niet). In adult Dutch, hoeven is an NPI that necessarily scopes under negation, giving rise to a NOT > NECESSARY reading. The findings from a hidden-object task with 5- and 6-year-old children showed that children's performance is suggestive of an interpretation of sentences with hoeft niet in which the modal scopes over negation (NECESSARY > NOT). This is in line with the Semantic Subset Principle that dictates that children should opt for the strongest possible reading in case of potential scope ambiguities. The full pattern of results, however, seems to be determined, in addition, by a particular strategy children use when facing uncertainty called Premature Closure.

  2. Strong 3D and 1D magnetism in hexagonal Fe-chalcogenides FeS and FeSe vs. weak magnetism in hexagonal FeTe

    Energy Technology Data Exchange (ETDEWEB)

    Parker, David S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-13

    We present a comparative theoretical study of the hexagonal forms of the Fe-chalcogenides FeS, FeSe and FeTe with their better known tetragonal forms. While the tetragonal forms exhibit only an incipient antiferromagnetism and experimentally show superconductivity when doped, the hexagonal forms of FeS and FeSe display a robust magnetism. We show that this strong magnetism arises from a van Hove singularity associated with the direct Fe-Fe c-axis chains in the generally more three-dimensional NiAs structure. We also find that hexagonal FeTe is much less magnetic than the other two hexagonal materials, so that unconventional magnetically-mediated superconductivity is possible, although a large Tc value is unlikely.

  3. Strong 3D and 1D magnetism in hexagonal Fe-chalcogenides FeS and FeSe vs. weak magnetism in hexagonal FeTe.

    Science.gov (United States)

    Parker, David S

    2017-06-13

    We present a comparative theoretical study of the hexagonal forms of the Fe-chalcogenides FeS, FeSe and FeTe with their better known tetragonal forms. While the tetragonal forms exhibit only an incipient antiferromagnetism and experimentally show superconductivity when doped, the hexagonal forms of FeS and FeSe display a robust magnetism. We show that this strong magnetism arises from a van Hove singularity associated with the direct Fe-Fe c-axis chains in the generally more three-dimensional NiAs structure. We also find that hexagonal FeTe is much less magnetic than the other two hexagonal materials, so that unconventional magnetically-mediated superconductivity is possible, although a large T c value is unlikely.

  4. Signatures of pairing in the magnetic excitation spectrum of strongly correlated two-leg ladders

    Science.gov (United States)

    Nocera, A.; Patel, N. D.; Dagotto, E.; Alvarez, G.

    2017-11-01

    Magnetic interactions are widely believed to play a crucial role in the microscopic mechanism leading to high critical temperature superconductivity. It is therefore important to study the signatures of pairing in the magnetic excitation spectrum of simple models known to show unconventional superconducting tendencies. Using the density matrix renormalization group technique, we calculate the dynamical spin structure factor S (k ,ω ) of a generalized t -U -J Hubbard model away from half filling in a two-leg ladder geometry. The addition of J enhances pairing tendencies. We analyze quantitatively the signatures of pairing in the magnetic excitation spectra. We found that the superconducting pair-correlation strength, that can be estimated independently from ground state properties, is closely correlated with the integrated low-energy magnetic spectral weight in the vicinity of (π ,π ) . In this wave-vector region, robust spin incommensurate features develop with increasing doping. The branch of the spectrum with rung direction wave vector krung=0 does not change substantially with doping where pairing dominates and thus plays a minor role. We discuss the implications of our results for neutron scattering experiments, where the spin excitation dynamics of hole-doped quasi-one-dimensional magnetic materials can be measured and also address implications for recent resonant inelastic x-ray scattering experiments.

  5. Layered Black Phosphorus: Strongly Anisotropic Magnetic, Electronic, and Electron-Transfer Properties.

    Science.gov (United States)

    Sofer, Zdeněk; Sedmidubský, David; Huber, Štěpán; Luxa, Jan; Bouša, Daniel; Boothroyd, Chris; Pumera, Martin

    2016-03-01

    Layered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer- and inner-sphere molecular probes is highly anisotropic. The electron-transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. H32+ molecular ion in a strong magnetic field: Triangular configuration

    International Nuclear Information System (INIS)

    Lopez Vieyra, J.C.; Turbiner, A.V.

    2002-01-01

    The existence of the molecular ion H 3 2+ in a magnetic field in a triangular configuration is revised. A variational method with an optimization of the form of the vector potential (gauge fixing) is used. It is shown that in the range of magnetic fields 10 8 11 G the system (pppe), with the protons forming an equilateral triangle perpendicular to the magnetic line, has a well-pronounced minimum in the total energy. This configuration is unstable under the decays (H atom)+p+p and H 2 + +p. The triangular configuration of H 3 2+ complements H 3 2+ in the linear configuration that exists for B > or approx. 10 10 G

  7. H2+ molecular ion in a strong magnetic field: Ground state

    International Nuclear Information System (INIS)

    Turbiner, A. V.; Lopez Vieyra, J. C.

    2003-01-01

    A detailed quantitative analysis of the system of two protons and one electron (ppe) placed in magnetic field ranging from 10 9 -4.414x10 13 G is presented. The present study is focused on the question of the existence of the molecular ion H 2 + in a magnetic field. A variational method with an optimization of the form of the vector potential (optimal gauge fixing) is used as a tool. It is shown that in the domain of applicability of the nonrelativistic approximation the (ppe) system in the Born-Oppenheimer approximation has a well-pronounced minimum in the total energy at a finite interproton distance for B(less-or-similar sign)10 11 G, thus manifesting the existence of H 2 + . For B(greater-or-similar sign)10 11 G and large inclinations (of the molecular axis with respect to the magnetic line) the minimum disappears and hence the molecular ion H 2 + does not exist. It is shown that the most stable configuration of H 2 + always corresponds to protons situated along the magnetic line. With magnetic field growth the H 2 + ion becomes more and more tightly bound and compact, and the electronic distribution evolves from a two-peak to a one-peak pattern. The domain of inclinations where the H 2 + ion exists reduces with magnetic field increase and finally becomes 0 degree sign -25 degree sign at B=4.414x10 13 G. Phase-transition-type behavior of variational parameters for some interproton distances related to the beginning of the chemical reaction H 2 + ↔H+p is found

  8. Electromagnetic processes in pulsars under strong electric and magnetic field conditions

    International Nuclear Information System (INIS)

    Ayasli, S.; Hacinliyan, A.; Oegelman, H.B.; Daugherty, I.K.

    1977-01-01

    It is believed that pulsars possess huge electric and magnetic fields. However, the electric field is commonly neglected in calculations of the rate of pair production, a process which is thought to be greatly important in the radiation mechanisms of pulsars. To see the effect of the electric field, the pair production is calculated for arbitrary electric and magnetic field configurations. The formulae thus obtained are then applied to pulsars. It is shown that the correction to the ''polar gap'' height calculated in the Ruderman and Sutherland model is negligible, although it might be important for the spectrum of emerging photons. (author)

  9. Exchange interaction of strongly anisotropic tripodal erbium single-ion magnets with metallic surfaces

    DEFF Research Database (Denmark)

    Dreiser, Jan; Wäckerlin, Christian; Ali, Md. Ehesan

    2014-01-01

    We present a comprehensive study of Er(trensal) single-ion magnets deposited in ultrahigh vacuum onto metallic surfaces. X-ray photoelectron spectroscopy reveals that the molecular structure is preserved after sublimation, and that the molecules are physisorbed on Au(111) while they are chemisorbed....... Furthermore XMCD indicates a weak antiferromagnetic exchange coupling between the single-ion magnets and the ferromagnetic Ni/Cu(100) substrate. For the latter case, spin-Hamiltonian fits to the XMCD M(H) suggest a significant structural distortion of the molecules. Scanning tunneling microscopy reveals...

  10. Nonlinear dispersion of resonance extraordinary wave in a plasma with strong magnetic field

    International Nuclear Information System (INIS)

    Krasovitskiy, V. B.; Turikov, V. A.; Sotnikov, V. I.

    2007-01-01

    In this paper, the efficiency of electron acceleration by a short, powerful laser pulse propagating across an external magnetic field is investigated. Conditions for the decay of a laser pulse with frequency close to the upper hybrid resonance frequency are analyzed. It is also shown that a laser pulse propagating as an extraordinary wave in cold, magnetized, low-density plasma takes the form of a nonlinear wave with the modulated amplitude (envelope soliton). Finally, simulation results on the interaction of an electromagnetic pulse with a semi-infinite plasma, obtained with the help of an electromagnetic relativistic PIC code, are discussed and a comparison with the obtained theoretical results is presented

  11. Optimizing charge neutralization for a magnetic sector SIMS instrument in negative mode

    Energy Technology Data Exchange (ETDEWEB)

    Pivovarov, Alexander L.; Guryanov, Georgiy M. [Corning Incorporated, SP-FR-01-01, Corning, New York 14831 (United States)

    2012-07-15

    Successful self-adjusted charge compensation was demonstrated for a CAMECA magnetic-sector secondary ion mass spectrometer applied in negative mode. Operation with the normal-incidence electron gun (NEG) potential positively biased relative to a sample potential enables substantial broadening of the Cs primary-ion-current density range available for analysis of insulators. The decrease of the negative NEG potential by 30 V allows the highest value of primary current density used for the analysis of a silica sample to increase by a factor of more than 6. By applying the improved charge neutralization technique, accurate Na depth profiles for SiO{sub 2} samples were obtained within detection limits of {approx}3 Multiplication-Sign 10{sup 15} atoms/cm{sup 3}.

  12. Path-integral calculation of the density of states in heavily doped strongly compensated semiconductors in a magnetic field

    International Nuclear Information System (INIS)

    Koinov, Z.G.; Yanchev, I.Y.

    1981-09-01

    The density of states in heavily doped strongly compansated semiconductors in a strong magnetic field is calculated by using the path-integral method. The case is considered when correlation exists in the impurity positions owing to the Coulomb interactions between the charged donors and acceptors during the high-temperature preparation of the samples. The semiclassical formula is rederived and corrections to it due to the long-range character of the potential and its short-range fluctuations are obtained. The density of states in the tail is studied and analytical results are given in the classical and quantum cases. (author)

  13. Onset of magnetic order in strongly-correlated systems from ab initio electronic structure calculations: application to transition metal oxides

    Science.gov (United States)

    Hughes, I. D.; Däne, M.; Ernst, A.; Hergert, W.; Lüders, M.; Staunton, J. B.; Szotek, Z.; Temmerman, W. M.

    2008-06-01

    We describe an ab initio theory of finite temperature magnetism in strongly-correlated electron systems. The formalism is based on spin density functional theory, with a self-interaction corrected local spin density approximation (SIC-LSDA). The self-interaction correction is implemented locally, within the Kohn-Korringa-Rostoker (KKR) multiple-scattering method. Thermally induced magnetic fluctuations are treated using a mean-field 'disordered local moment' (DLM) approach and at no stage is there a fitting to an effective Heisenberg model. We apply the theory to the 3d transition metal oxides, where our calculations reproduce the experimental ordering tendencies, as well as the qualitative trend in ordering temperatures. We find a large insulating gap in the paramagnetic state which hardly changes with the onset of magnetic order.

  14. Strong out-of-plane magnetic anisotropy in ion irradiated anatase TiO2 thin films

    Directory of Open Access Journals (Sweden)

    M. Stiller

    2016-12-01

    Full Text Available The temperature and field dependence of the magnetization of epitaxial, undoped anatase TiO2 thin films on SrTiO3 substrates was investigated. Low-energy ion irradiation was used to modify the surface of the films within a few nanometers, yet with high enough energy to produce oxygen and titanium vacancies. The as-prepared thin film shows ferromagnetism which increases after irradiation with low-energy ions. An optimal and clear magnetic anisotropy was observed after the first irradiation, opposite to the expected form anisotropy. Taking into account the experimental parameters, titanium vacancies as di-Frenkel pairs appear to be responsible for the enhanced ferromagnetism and the strong anisotropy observed in our films. The magnetic impurities concentrations was measured by particle-induced X-ray emission with ppm resolution. They are ruled out as a source of the observed ferromagnetism before and after irradiation.

  15. High Magnetic Field Study on Giant Negative Magnetoresistance in the Molecular Conductor TPP[Cr(Pc)(CN)2]2

    Science.gov (United States)

    Ikeda, Mitsuo; Kida, Takanori; Tahara, Time; Murakawa, Hiroshi; Nishi, Miki; Matsuda, Masaki; Hagiwara, Masayuki; Inabe, Tamotsu; Hanasaki, Noriaki

    2016-06-01

    We investigated the magnetic and transport properties of the phthalocyanine molecular conductor TPP[Cr(Pc)(CN)2]2 in magnetic fields of up to 54 T. We observed giant negative magnetoresistance which hardly depends on the magnetic field direction owing to the isotropic nature confirmed by electron spin resonance measurements. The magnitude of magnetoresistance [|ρ(μ0H)/ρ(0 T) - 1|] is proportional to the square of magnetization as observed in the case of the spin scattering process, while the proportionality coefficient increases with decreasing the temperature. The magnetization does not saturate even at 53 T, indicating the existence of the large antiferromagnetic exchange interactions between the localized spins. In spite of this antiferromagnetic exchange interaction and low dimensionality, a convex magnetization curve was observed in the low temperature and high magnetic field range. To reproduce this magnetization curve, we proposed a model taking into account the antiferromagnetic exchange interaction between the neighboring π-electron spins.

  16. Imposed, ordered dust structures and other plasma features in a strongly magnetized plasma

    Science.gov (United States)

    Thomas, Edward; Leblanc, Spencer; Lynch, Brian; Konopka, Uwe; Merlino, Robert; Rosenberg, Marlene

    2015-11-01

    The Magnetized Dusty Plasma Experiment (MDPX) device has been in operation for just over one year. In that time, the MDPX device has been operating using a uniform magnetic field configuration up to 3.0 Tesla and has successfully produced plasmas and dusty plasmas at high magnetic fields. In these experimental studies, we have made observations of a new type of imposed, ordered structure in a dusty plasma at magnetic fields above 1 T. These dusty plasma structures are shown to scale inversely with neutral pressure and are shown to reflect the spatial structure of a wire mesh placed in the plasma. Additionally, recent measurements have been made that give insights into the effective potential that establishes the ordered structures in the plasma. In this presentation, we report on details of the imposed, ordered dusty plasma structure as well as filamentary features that also appear in the plasma and modify the confinement of the dusty plasma. This work is supported with funding from the NSF and Department of Energy.

  17. Parallel-beam correlation technique for measuring density fluctuations in plasmas with strong magnetic shear

    International Nuclear Information System (INIS)

    Jacobson, A.R.

    1981-04-01

    A laser diagnostic scheme is described which facilitates localization of density fluctuations along the line of sight. The method exploits both the generally observed anisotropy of density fluctuations in low-beta plasmas, as well as the twisting of the magnetic field which occurs across the minor diameter of reversed-field pinches, spheromaks, etc. Both interferometric and schlieren variations are discussed

  18. High-latitude ionospheric convection during strong interplanetary magnetic field B-y

    DEFF Research Database (Denmark)

    Huang, C.S.; Sofko, G.J.; Murr, D.

    1999-01-01

    . The interplanetary magnetic field (IMF) conditions corresponding to the occurrence of the ionospheric convection were B-x approximate to 1 nT, B-y approximate to 10 nT, and B-z y). We have compared our observations with statistical patterns and MHD numerical models for similar IMF...

  19. The Vlasov equation with strong magnetic field and oscillating electric field as a model for isotop resonant separation

    Directory of Open Access Journals (Sweden)

    Emmanuel Frenod

    2002-01-01

    Full Text Available We study the qualitative behavior of solutions to the Vlasov equation with strong external magnetic field and oscillating electric field. This model is relevant to the understanding of isotop resonant separation. We show that the effective equation is a kinetic equation with a memory term. This memory term involves a pseudo-differential operator whose kernel is characterized by an integral equation involving Bessel functions. The kernel is explicitly given in some particular cases.

  20. Tunable photonic crystal for THz radiation in layered superconductors: Strong magnetic-field dependence of the transmission coefficient

    International Nuclear Information System (INIS)

    Savel'ev, Sergey; Rakhmanov, A.L.; Nori, Franco

    2006-01-01

    Josephson plasma waves are scattered by the Josephson vortex lattice. This scattering results in a strong dependence, on the in-plane magnetic-field H ab , of the reflection and transmission of THz radiation propagating in layered superconductors. In particular, a tunable band-gap structure (THz photonic crystal) occurs in such a medium. These effects can be used, by varying H ab , for the selective frequency-filtering of THz radiation

  1. Current-density functional theory study of the H2 molecule evolving under a strong ultrashort magnetic field

    Science.gov (United States)

    Vikas, Hash(0xb7f6e60)

    2012-01-01

    Hydrogen molecule in a strong ultrashort magnetic field is investigated through a current-density functional theory (CDFT) and quantum fluid dynamics (QFD) based approach employing current-density dependent vector exchange-correlation potential and energy density functional derived with a vorticity variable. The numerical computations through the CDFT based approach are performed for the H2 molecule, starting initially from its field-free ground state, in a parallel internuclear axis and magnetic field-axis configuration with the internuclear separation R ranging from 0.1 a.u. to 14.0 a.u., and the strength of the time-dependent (TD) magnetic field varying between 0-1011 G over a few femtoseconds. The numerical results are compared with that obtained using an approach based on the current-density independent approximation under similar computational constraints but employing only scalar exchange-correlation potential dependent on the electronic charge-density alone. The current-density based approach yields exchange- and correlation energy as well as electronic charge-density of the H2 molecule drastically different from that obtained using current-independent approach, in particular, at TD magnetic field-strengths >109 G during a typical time-period of the field when the magnetic-field had attained maximum applied field-strength and is switched to a decreasing ramp function. This nonadiabatic behavior of the TD electronic charge-density is traced to the TD vorticity-dependent vector exchange-correlation potential of the CDFT based approach. The interesting electron dynamics of the H2 molecule in strong TD magnetic field is further elucidated by treating electronic charge-density as an `electron-fluid'. The present work also reveals interesting real-time dynamics on the attosecond time-scale in the electronic charge-density distribution of the hydrogen molecule.

  2. Hall effect in a strong magnetic field: Direct comparisons of compressible magnetohydrodynamics and the reduced Hall magnetohydrodynamic equations

    International Nuclear Information System (INIS)

    Martin, L. N.; Dmitruk, P.; Gomez, D. O.

    2010-01-01

    In this work we numerically test a model of Hall magnetohydrodynamics in the presence of a strong mean magnetic field: the reduced Hall magnetohydrodynamic model (RHMHD) derived by [Gomez et al., Phys. Plasmas 15, 102303 (2008)] with the addition of weak compressible effects. The main advantage of this model lies in the reduction of computational cost. Nevertheless, up until now the degree of agreement with the original Hall MHD system and the range of validity in a regime of turbulence were not established. In this work direct numerical simulations of three-dimensional Hall MHD turbulence in the presence of a strong mean magnetic field are compared with simulations of the weak compressible RHMHD model. The results show that the degree of agreement is very high (when the different assumptions of RHMHD, such as spectral anisotropy, are satisfied). Nevertheless, when the initial conditions are isotropic but the mean magnetic field is maintained strong, the results differ at the beginning but asymptotically reach a good agreement at relatively short times. We also found evidence that the compressibility still plays a role in the dynamics of these systems, and the weak compressible RHMHD model is able to capture these effects. In conclusion the weak compressible RHMHD model is a valid approximation of the Hall MHD turbulence in the relevant physical context.

  3. Ion-acoustic double layers in magnetized positive-negative ion plasmas with nonthermal electrons

    Science.gov (United States)

    El-Labany, S. K.; Sabry, R.; El-Taibany, W. F.; Elghmaz, E. A.

    2012-07-01

    The nonlinear ion-acoustic double layers (IADLs) in a warm magnetoplasma with positive-negative ions and nonthermal electrons are investigated. For this purpose, the hydrodynamic equations for the positive-negative ions, nonthermal electron density distribution, and the Poisson equation are used to derive a modified Zakharov-Kuznetsov (MZK) equation, in the small amplitude regime. It is found that compressive and rarefactive IADLs strongly depend on the mass and density ratios of the negative-to-positive ions as well as the nonthermal electron parameter. Also, it is shown that there are one critical value for the density ratio of the negative-to-positive ions ( ν), the ratio between unperturbed electron-to-positive ion density ( μ), and the nonthermal electron parameter ( β), which decide the existence of positive and negative IADLs. The present study is applied to examine the small amplitude nonlinear IADL excitations for the (H+, O2-) and (H+,H-) plasmas, where they are found in the D- and F-regions of the Earth's ionosphere. This investigation should be helpful in understanding the salient features of the nonlinear IADLs in either space or laboratory plasmas where two distinct groups of ions and non-Boltzmann distributed electrons are present.

  4. Strong room-temperature negative transconductance in an axial Si/Ge hetero-nanowire tunneling field-effect transistor

    Science.gov (United States)

    Zhang, Peng; Le, Son T.; Hou, Xiaoxiao; Zaslavsky, A.; Perea, Daniel E.; Dayeh, Shadi A.; Picraux, S. T.

    2014-08-01

    We report on room-temperature negative transconductance (NTC) in axial Si/Ge hetero-nanowire tunneling field-effect transistors. The NTC produces a current peak-to-valley ratio >45, a high value for a Si-based device. We characterize the NTC over a range of gate VG and drain VD voltages, finding that NTC persists down to VD = -50 mV. The physical mechanism responsible for the NTC is the VG-induced depletion in the p-Ge section that eventually reduces the maximum electric field that triggers the tunneling ID, as confirmed via three-dimensional (3D) technology computer-aided design simulations.

  5. Thermal electron transport in regimes with low and negative magnetic shear in Tore Supra

    International Nuclear Information System (INIS)

    Voitsekhovitch, I.; Litaudon, X.; Moreau, D.; Aniel, T.; Becoulet, A.; Erba, M.; Joffrin, E.; Kazarian-Vibert, F.; Peysson, Y.

    1997-01-01

    The magnetic shear effect on thermal electron transport is studied in a large variety of non-inductive plasmas in Tore Supra. An improved confinement in the region of low and negative shear was observed and quantified with an exponential dependence on the magnetic shear (Litaudon, et al., Fusion Energy 1996 (Proc. 16th Int. Conf. Montreal, 1996), Vol. 1, IAEA, Vienna (1997) 669). This is interpreted as a consequence of a decoupling of the global modes (Romanelli and Zonca, Phys. Fluids B 5 (1993) 4081) that are thought to be responsible for anomalous transport. This dependence is proposed in order to complete the Bohm-like L mode local electron thermal diffusivity so as to describe the transition from Bohm-like to gyroBohm transport in the plasma core. The good agreement between the predictive simulations of the different Tore Supra regimes (hot core lower hybrid enhanced performance, reversed shear plasmas and combined lower hybrid current drive and fast wave electron heating) and experimental data provides a basis for extrapolation of this magnetic shear dependence in the local transport coefficients to future machines. As an example, a scenario for non-inductive current profile optimization and control in ITER is presented. (author)

  6. Tunable magnetoresistance driven by magnetically sensitive negative differential resistance in an asymmetrically coupled single molecule junction

    Science.gov (United States)

    Warner, Ben; El Hallak, Fadi; Sharp, John; Persson, Mats; Fisher, Andrew J.; Hirjibehedin, Cyrus F.

    2014-03-01

    Using scanning tunneling microscopy, we study the effects of interactions between individual magnetic molecules that are separated from an underlying copper surface by a thin-insulating layer of copper nitride (Cu2N). For electrical transport through a junction containing an individual iron phthalocyanine (FePc) molecule on Cu2N, we observe two novel magnetoresistance behaviors that arise from negative differential resistance (NDR) that shifts by unexpectedly large amounts in a magnetic field. Because voltage is dropped asymmetrically in this double barrier junction, the FePc can become transiently charged when its states are aligned with the Fermi energy of the Cu, resulting in the observed NDR effect. Furthermore, the asymmetric coupling magnifies the observed voltage sensitivity of the magnetic field dependence of the NDR - which inherently is on the scale of the Zeeman energy - by almost two orders of magnitude. These findings represent a new basis for making magnetoresistance devices at the single molecule scale. Furthermore, the enhancement of the energy scales created by asymmetric coupling of the junction can be combined with other multi-step tunneling processes to allow for the investigation of other phenomena that normally would be difficult to observe.

  7. Thermal electron transport in the regimes with low and negative magnetic shear on tore supra

    International Nuclear Information System (INIS)

    Voitsekhovitch, I.; Litaudon, X.; Moreau, D.; Aniel, T.; Becoulet, A.; Erba, M.; Joffrin, E.; Kazarian-Vibert, F.; Peysson, Y.

    1997-04-01

    The magnetic shear effect on the thermal electron transport is studied in a large variety of non-inductive plasmas of Tore Supra. An improved confinement in the region of low and negative shear was observed and quantified with an exponential dependence on the magnetic shear [Litaudon et al. in Plasma Physics and Controlled Nuclear Fusion Research, 1996, Montreal (International Atomic Energy Agency, Vienna, 1997) to be published]. This is interpreted as the consequence of a decoupling of the global modes [Romanelli and Zonka, Phys. Fluids B5 (1993), 4081] which are thought to be responsible for anomalous transport. This dependence is proposed to complete the Bohm-like L-mode local electron thermal diffusivity to describe the transition from the Bohm-like to the gyro-Bohm transport in the plasma core. The good agreement between the predictive simulations of the different Tore Supra regimes (hot core lower hybrid enhanced performance, reversed shear plasmas and combined lower hybrid current drive and fast wave electron heating) and experimental data gives a basis for the extrapolation of this magnetic shear dependence in the local transport coefficients for future machines. As an example a scenario for non-inductive current profile optimisation and control in ITER is presented. (author)

  8. Flow of a two-dimensional liquid metal jet in a strong magnetic field

    International Nuclear Information System (INIS)

    Reed, C.B.; Molokov, S.

    2002-01-01

    Two-dimensional, steady flow of a liquid metal slender jet pouring from a nozzle in the presence of a transverse, nonuniform magnetic field is studied. The surface tension has been neglected, while gravity is shown to be not important. The main aim of the study is to evaluate the importance of the inertial effects. It has been shown that for gradually varying fields characteristic for the divertor region of a tokamak, inertial effects are negligible for N > 10, where N is the interaction parameter. Thus the inertialess flow model is expected to give good results even for relatively low magnetic fields and high jet velocity. Simple relations for the jet thickness and velocity have been derived. The results show that the jet becomes thicker if the field increases along the flow and thinner if it decreases

  9. Variational Monte Carlo calculations of lithium atom in strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Doma, S. B., E-mail: sbdoma@alexu.edu.eg [Alexandria University, Mathematics Department, Faculty of Science (Egypt); Shaker, M. O.; Farag, A. M. [Tanta University, Mathematics Department, Faculty of Science (Egypt); El-Gammal, F. N., E-mail: famta-elzahraa4@yahoo.com [Menofia University, Mathematics Department, Faculty of Science (Egypt)

    2017-01-15

    The variational Monte Carlo method is applied to investigate the ground state and some excited states of the lithium atom and its ions up to Z = 10 in the presence of an external magnetic field regime with γ = 0–100 arb. units. The effect of increasing field strength on the ground state energy is studied and precise values for the crossover field strengths were obtained. Our calculations are based on using accurate forms of trial wave functions, which were put forward in calculating energies in the absence of magnetic field. Furthermore, the value of Y at which ground-state energy of the lithium atom approaches to zero was calculated. The obtained results are in good agreement with the most recent values and also with the exact values.

  10. Magnetic field induced strong valley polarization in the three-dimensional topological semimetal LaBi

    Science.gov (United States)

    Kumar, Nitesh; Shekhar, Chandra; Klotz, J.; Wosnitza, J.; Felser, Claudia

    2017-10-01

    LaBi is a three-dimensional rocksalt-type material with a surprisingly quasi-two-dimensional electronic structure. It exhibits excellent electronic properties such as the existence of nontrivial Dirac cones, extremely large magnetoresistance, and high charge-carrier mobility. The cigar-shaped electron valleys make the charge transport highly anisotropic when the magnetic field is varied from one crystallographic axis to another. We show that the electrons can be polarized effectively in these electron valleys under a rotating magnetic field. We achieved a polarization of 60% at 2 K despite the coexistence of three-dimensional hole pockets. The valley polarization in LaBi is compared to the sister compound LaSb where it is found to be smaller. The performance of LaBi is comparable to the highly efficient bismuth.

  11. Magnetic susceptibility as a method of investigation of short-range order in strongly nonstoichiometric carbides

    International Nuclear Information System (INIS)

    Nazarova, S.Z.; Gusev, A.I.

    2001-01-01

    Magnetic susceptibility in disordered and ordered carbides of transition metals (M = Ti, Zr, Hf, Nb, Ta) was studied, the results are generalized. It was ascertained that the change in carbide susceptibility induced by deviation from stoichiometry stems from specific features of electronic spectra of the compounds. The use of magnetic susceptibility for determining structural disorder-order transitions is discussed. It is shown that change in the contribution made by orbital paramagnetism, resulting from short-range order formation, is the reason of decrease in susceptibility of nonstoichiometric carbides during the ordering. Experimentally obtained data on susceptibility permitted evaluating short- and far-range order parameters in NbC y , TaC y , TiC y and HfC y carbides [ru

  12. A kinetic model of retarding field analyser measurements in strongly magnetized, flowing, collisional plasmas

    Czech Academy of Sciences Publication Activity Database

    Gunn, J. P.; Fuchs, Vladimír; Kočan, M.

    2013-01-01

    Roč. 55, č. 4 (2013), 045012-045012 ISSN 0741-3335 R&D Projects: GA MŠk 7G10072 Institutional support: RVO:61389021 Keywords : plasma * collisions * magnetic field * retarding field analyzer Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.386, year: 2013 http://iopscience.iop.org/0741-3335/55/4/045012/pdf/0741-3335_55_4_045012.pdf

  13. The LACARA Vacuum Laser Accelerator Experiment: Beam Positioning and Alignment in a Strong Magnetic Field

    International Nuclear Information System (INIS)

    Shchelkunov, Sergey V.; Marshall, T. C.; Hirshfield, J. L.; Wang, Changbiao; LaPointe, M. A.

    2006-01-01

    LACARA (laser cyclotron auto-resonance accelerator) is a vacuum laser accelerator of electrons that is under construction at the Accelerator Test Facility (ATF), Brookhaven National Laboratory. It is expected that the experiment will be assembled by September 2006; this paper presents progress towards this goal. According to numerical studies, as an electron bunch moves along the LACARA solenoidal magnetic field (∼5.2 T, length ∼1 m), it will be accelerated from 50 to ∼75 MeV by interacting with a 0.8 TW Gaussian-mode circularly polarized optical pulse provided by the ATF CO2 10.6μm laser system. The LACARA laser transport optics must handle 10 J and be capable of forming a Gaussian beam inside the solenoid with a 1.4 mm waist and a Rayleigh range of 60 cm. The electron optics must transport a bunch having input emittance of 0.015 mm-mrad and 100 μm waist through the magnet. Precision alignment between the electron beam and the solenoid magnetic axis is required, and a method to achieve this is described in detail. Emittance- filtering may be necessary to yield an accelerated bunch having a narrow (∼1%) energy-spread

  14. Structural analysis of mixed alkali borosilicate glasses containing Cs+ and Na+ using strong magnetic field magic angle spinning nuclear magnetic resonance

    Directory of Open Access Journals (Sweden)

    S. Kaneko

    2017-03-01

    Full Text Available We have investigated the local structure of alkali atoms in mixed alkali silicate, borate, and borosilicate glasses, which contain Cs+ and Na+, using strong magnetic field magic angle spinning nuclear magnetic resonance (MAS NMR spectroscopy of 133Cs and 23Na. The spectral peaks of 133Cs in borosilicate (Si:B = 1:1 and Si-rich borosilicate (Si:B = 2:1 glasses shifted to upfield with increasing Cs+/(Na+ + Cs+ ratio, which implies that the coordination number of Cs+ decreased as in the case of silicate and borate glasses. However, this trend was not observed in the 23Na spectra of either borosilicate glass. This might be because the chemical shift of 23Na in borosilicate glass is strongly affected by nearby species such as Si or B, and not by the coordination number of Na+.

  15. Three-dimensional modeling of a negative ion source with a magnetic filter: impact of biasing the plasma electrode on the plasma asymmetry

    Science.gov (United States)

    Fubiani, G.; Boeuf, J. P.

    2015-10-01

    The effect on the plasma characteristics of biasing positively the plasma electrode (PE) in negative ion sources with a magnetic filter is analysed using a 3D particle-in-cell model with Monte-Carlo collisions (PIC-MCC). We specialize to the one driver (i.e. one inductively coupled radio-frequency discharge) BATMAN negative ion source and the 4-drivers (large volume) ELISE device. Both are ITER prototype high power tandem-type negative ion sources developed for the neutral beam injector (NBI) system. The plasma is generated in the driver and diffuses inside the second chamber which is magnetized. Asymmetric plasma profiles originate from the formation of an electric field transverse to the electron current flowing through the magnetic filter (Hall effect). The model shows that the importance of the asymmetry increases with the PE bias potential, i.e. with the electron flow from the driver to the extraction region and depends on the shape of the magnetic filter field. We find that although the plasma density and potential profiles may be more or less asymmetric depending on the filter field configuration, the electron current to the plasma grid is always strongly asymmetric.

  16. Magnetic study of a few antiferromagnets in very-strong pulsed fields (450 kOE)

    International Nuclear Information System (INIS)

    Krebs, J.

    1968-01-01

    In this thesis we describe a pulsed field device with which we obtain magnetization curves up to 450 kOE at all temperatures between 1. 6 and 300. We have studied the 'spin-flopping'(and therefore the anisotropy) in MnF 2 versus temperature, below the Neel point. We have also studied the antiferromagnets MnSO 4 . and MnSO 4 .H 2 O which have revealed saturation fields respectively of 250 kOE and 320 kOE. (author) [fr

  17. Measurement of low-frequency magnetic pulses from negative stepped leaders in rocket-triggered lightning flashes

    Science.gov (United States)

    Lu, Gaopeng

    2017-04-01

    Measurement of low-frequency magnetic pulses from negative stepped leaders in rocket-triggered lightning flashes Gaopeng Lu,1,2 Yanfeng Fan,1,3 Hongbo Zhang,1,3 Rubin Jiang,1,2 Mingyuan Liu,1,2 and Xiushu Qie,1,2 1. Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China 2. Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, Jiangsu 210044, China 3. University of Chinese Academy of Sciences, Beijing 100049, China We report the measurement of magnetic pulses from the negative stepped leaders in positive rocket-triggered lightning flashes with the low-frequency (4 kHz to 420 kHz) magnetic sensor at two different distances (78 m and 970 m, respectively) during the SHantong Artificial Triggered Lightning Experiments (SHATLE) during summer of 2015. Different from the magnetic radiation from positive leaders as observed in the considerably more frequent cases, the impulsive signals from the negative leader sustain for a much longer time interval, while the attenuation of current pulse launched by the stepping of leader is also observed. The general pattern of magnetic pulses observed for the negative stepped leader is different from the positive counterpart. Also, the initial negative leader appears to be brighter than the positive ones, as shown by both high-speed video observation and the magnetic measurement.

  18. Accretion disc dynamo activity in local simulations spanning weak-to-strong net vertical magnetic flux regimes

    Science.gov (United States)

    Salvesen, Greg; Simon, Jacob B.; Armitage, Philip J.; Begelman, Mitchell C.

    2016-03-01

    Strongly magnetized accretion discs around black holes have attractive features that may explain enigmatic aspects of X-ray binary behaviour. The structure and evolution of these discs are governed by a dynamo-like mechanism, which channels part of the accretion power liberated by the magnetorotational instability (MRI) into an ordered toroidal magnetic field. To study dynamo activity, we performed three-dimensional, stratified, isothermal, ideal magnetohydrodynamic shearing box simulations. The strength of the self-sustained toroidal magnetic field depends on the net vertical magnetic flux, which we vary across almost the entire range over which the MRI is linearly unstable. We quantify disc structure and dynamo properties as a function of the initial ratio of mid-plane gas pressure to vertical magnetic field pressure, β _0^mid = p_gas / p_B. For 10^5 ≥ β _0^mid ≥ 10 the effective α-viscosity parameter scales as a power law. Dynamo activity persists up to and including β _0^mid = 10^2, at which point the entire vertical column of the disc is magnetic pressure dominated. Still stronger fields result in a highly inhomogeneous disc structure, with large density fluctuations. We show that the turbulent steady state βmid in our simulations is well matched by the analytic model of Begelman et al. describing the creation and buoyant escape of toroidal field, while the vertical structure of the disc can be broadly reproduced using this model. Finally, we discuss the implications of our results for observed properties of X-ray binaries.

  19. A strong, highly-tilted interstellar magnetic field near the Solar System.

    Science.gov (United States)

    Opher, M; Bibi, F Alouani; Toth, G; Richardson, J D; Izmodenov, V V; Gombosi, T I

    2009-12-24

    Magnetic fields play an important (sometimes dominant) role in the evolution of gas clouds in the Galaxy, but the strength and orientation of the field in the interstellar medium near the heliosphere has been poorly constrained. Previous estimates of the field strength range from 1.8-2.5 microG and the field was thought to be parallel to the Galactic plane or inclined by 38-60 degrees (ref. 2) or 60-90 degrees (ref. 3) to this plane. These estimates relied either on indirect observational inferences or modelling in which the interstellar neutral hydrogen was not taken into account. Here we report measurements of the deflection of the solar wind plasma flows in the heliosheath to determine the magnetic field strength and orientation in the interstellar medium. We find that the field strength in the local interstellar medium is 3.7-5.5 microG. The field is tilted approximately 20-30 degrees from the interstellar medium flow direction (resulting from the peculiar motion of the Sun in the Galaxy) and is at an angle of about 30 degrees from the Galactic plane. We conclude that the interstellar medium field is turbulent or has a distortion in the solar vicinity.

  20. Large negative magnetic contribution to the thermal expansion in iron-platinum alloys: quantitative theory of the Invar effect.

    Science.gov (United States)

    Khmelevskyi, S; Turek, I; Mohn, P

    2003-07-18

    We show that the large negative magnetic contribution to the thermal expansion in disordered Fe-Pt alloys can be understood within the disordered local moment (DLM) approach. On the basis of first principles calculations we quantitatively describe the spontaneous volume magnetostriction for various Pt concentrations. It is found that the Invar effect in these alloys is entirely related to the state of thermal magnetic disorder modeled by the DLM states. We also show that the experimentally observed anomaly in the temperature dependence of the magnetization is due to a spontaneous reduction of the local magnetic moments rather than to "hidden excitations."

  1. Starting off on the right foot: strong right-footers respond faster with the right foot to positive words and with the left foot to negative words.

    Science.gov (United States)

    de la Vega, Irmgard; Graebe, Julia; Härtner, Leonie; Dudschig, Carolin; Kaup, Barbara

    2015-01-01

    Recent studies have provided evidence for an association between valence and left/right modulated by handedness, which is predicted by the body-specificity hypothesis (Casasanto, 2009) and also reflected in response times. We investigated whether such a response facilitation can also be observed with foot responses. Right-footed participants classified positive and negative words according to their valence by pressing a key with their left or right foot. A significant interaction between valence and foot only emerged in the by-items analysis. However, when dividing participants into two groups depending on the strength of their footedness, an interaction between valence and left/right was observed for strong right-footers, who responded faster with the right foot to positive words, and with the left foot to negative words. No interaction emerged for weak right-footers. The results strongly support the assumption that fluency lies at the core of the association between valence and left/right.

  2. The dynamics of magnetic Rossby waves in spherical dynamo simulations: A signature of strong-field dynamos?

    Science.gov (United States)

    Hori, K.; Teed, R. J.; Jones, C. A.

    2018-03-01

    We investigate slow magnetic Rossby waves in convection-driven dynamos in rotating spherical shells. Quasi-geostrophic waves riding on a mean zonal flow may account for some of the geomagnetic westward drifts and have the potential to allow the toroidal field strength within the planetary fluid core to be estimated. We extend the work of Hori et al. (2015) to include a wider range of models, and perform a detailed analysis of the results. We find that a predicted dispersion relation matches well with the longitudinal drifts observed in our strong-field dynamos. We discuss the validity of our linear theory, since we also find that the nonlinear Lorentz terms influence the observed waveforms. These wave motions are excited by convective instability, which determines the preferred azimuthal wavenumbers. Studies of linear rotating magnetoconvection have suggested that slow magnetic Rossby modes emerge in the magnetostrophic regime, in which the Lorentz and Coriolis forces are in balance in the vorticity equation. We confirm this to be predominant balance for the slow waves we have detected in nonlinear dynamo systems. We also show that a completely different wave regime emerges if the magnetic field is not present. Finally we report the corresponding radial magnetic field variations observed at the surface of the shell in our simulations and discuss the detectability of these waves in the geomagnetic secular variation.

  3. Magnetic resonance imaging findings in spinal tuberculosis: Comparison of HIV positive and negative patients

    Directory of Open Access Journals (Sweden)

    Cameron Michael Anley

    2012-01-01

    Full Text Available Background: There is an increasing incidence of Human immunodeficiency virus (HIV and tuberculosis (TB co-infection. This has led to an increasing number of atypical features on magnetic resonance imaging (MRI. We postulated that the type 4 hypersensitivity response causing granulomatous inflammation may be disrupted by the HIV resulting in less vertebral body destruction. This study compares the MRI features of spinal tuberculosis in HIV positive and negative patients. Materials and Methods: Fifty patients with confirmed spinal tuberculosis, HIV status and available MRI scans at a single institution from 2003-2009 were identified. HIV status was positive in 20 and negative in 30. Females were predominant (34:16. The HIV positive group was younger at 32.4 versus 46 years (P=0.008. Blood parameters (WCC, ESR, Hb, Lymphocyte count were not significantly different between the HIV groups. MRI scans were reviewed by a radiologist who was blinded to the HIV status. Site, extent of disease, body collapse, abscess location and volume, kyphotic deformity and cord signal were reported. Results: There was no difference between the number of vertebral bodies affection with TB involvement, presence of cord signal or incidence of non-contiguous lesions. The HIV negative group had significantly more total vertebral collapse (P=0.036 and greater kyphosis (P=0.002. The HIV positive group had a trend to larger anterior epidural pus collection (P=0.2. Conclusion: HIV negative patients demonstrate greater tuberculous destruction in terms of total percentage body collapse and resultant kyphosis. There is no difference in the incidence of cord signal or presence of non-contiguous lesions. HIV positive patients show a trend to a greater epidural abscess volume. This difference may be explained by the reduced autoimmune response of the type 4 hypersensitivity reaction caused by the HIV infection.

  4. On the thermoelectric power in degenerate narrow gap semiconductors in the presence of a strong magnetic field

    International Nuclear Information System (INIS)

    Ghatak, K.P.; De, B.

    1991-01-01

    In this paper the authors have studied the thermoelectric power under strong magnetic field in degenerate semiconductors on the basis of fourth order in affective mass theory and taking into account the interactions of the conduction electrons, heavy-holes, light-holes and split-off holes respectively. The results obtained are then compared to those derived on the basis of the well-known three-band Kane model. It is found, taking n-Hg 1-x Cd x Te as an example, that the magneto-thermo power increases with decreasing electron concentration and increasing magnetic field respectively for both the models in an oscillatory way. The oscillations are due to SdH effects and the theoretical analysis in accordance with fourth order in effective mass theory i in agreement with the experimental observation as reported elsewhere. In addition, the corresponding results for parabolic energy bands have also been obtained as special cases of our generalized formulations

  5. Preparation of cold ions in strong magnetic field and its application to gas-phase NMR spectroscopy

    International Nuclear Information System (INIS)

    Fuke, K.; Ohshima, Y.; Tona, M.

    2015-01-01

    Nuclear Magnetic Resonance (NMR) technique is widely used as a powerful tool to study the physical and chemical properties of materials. However, this technique is limited to the materials in condensed phases. To extend this technique to the gas-phase molecular ions, we are developing a gas-phase NMR apparatus. In this note, we describe the basic principle of the NMR detection for molecular ions in the gas phase based on a Stern-Gerlach type experiment in a Penning trap and outline the apparatus under development. We also present the experimental procedures and the results on the formation and the manipulation of cold ions under a strong magnetic field, which are the key techniques to detect the NMR by the present method

  6. Analytical GIAO and hybrid-basis integral derivatives: application to geometry optimization of molecules in strong magnetic fields.

    Science.gov (United States)

    Tellgren, Erik I; Reine, Simen S; Helgaker, Trygve

    2012-07-14

    Analytical integral evaluation is a central task of modern quantum chemistry. Here we present a general method for evaluating differentiated integrals over standard Gaussian and mixed Gaussian/plane-wave hybrid orbitals. The main idea is to have a representation of basis sets that is flexible enough to enable differentiated integrals to be reinterpreted as standard integrals over modified basis functions. As an illustration of the method, we report a very simple implementation of Hartree-Fock level geometrical derivatives in finite magnetic fields for gauge-origin independent atomic orbitals, within the London program. As a quantum-chemical application, we optimize the structure of helium clusters and some well-known covalently bound molecules (water, ammonia and benzene) subject to strong magnetic fields.

  7. Magnetic properties of Hf177 and Hf180 in the strong-coupling deformed model

    Science.gov (United States)

    Muto, S.; Stone, N. J.; Bingham, C. R.; Stone, J. R.; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.; Nikolov, J.; Nishimura, K.; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G. S.; Veskovic, M.; Walters, W. B.

    2014-04-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2-, 51.4 m, 2740 keV state in Hf177 and the 8-, 5.5 h, 1142 keV state in Hf180 by the method of on-line nuclear orientation. Also included are results on the angular distributions of γ transitions in the decay of the Hf177 isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2+, 1.1 s, isomer at 1315 keV and on the 9/2+, 0.663 ns, isomer at 321 keV. The new results are discussed in the light of the recently reported finding of systematic dependence of the behavior of the gR parameter upon the quasiproton and quasineutron make up of high-K isomeric states in this region.

  8. Dst Index in the 2008 GEM Modeling Challenge - Model Performance for Moderate and Strong Magnetic Storms

    Science.gov (United States)

    Rastaetter, Lutz; Kuznetsova, Maria; Hesse, Michael; Chulaki, Anna; Pulkkinen, Antti; Ridley, Aaron J.; Gombosi, Tamas; Vapirev, Alexander; Raeder, Joachim; Wiltberger, Michael James; hide

    2010-01-01

    The GEM 2008 modeling challenge efforts are expanding beyond comparing in-situ measurements in the magnetosphere and ionosphere to include the computation of indices to be compared. The Dst index measures the largest deviations of the horizontal magnetic field at 4 equatorial magnetometers from the quiet-time background field and is commonly used to track the strength of the magnetic disturbance of the magnetosphere during storms. Models can calculate a proxy Dst index in various ways, including using the Dessler-Parker Sckopke relation and the energy of the ring current and Biot-Savart integration of electric currents in the magnetosphere. The GEM modeling challenge investigates 4 space weather events and we compare models available at CCMC against each other and the observed values of Ost. Models used include SWMF/BATSRUS, OpenGGCM, LFM, GUMICS (3D magnetosphere MHD models), Fok-RC, CRCM, RAM-SCB (kinetic drift models of the ring current), WINDMI (magnetosphere-ionosphere electric circuit model), and predictions based on an impulse response function (IRF) model and analytic coupling functions with inputs of solar wind data. In addition to the analysis of model-observation comparisons we look at the way Dst is computed in global magnetosphere models. The default value of Dst computed by the SWMF model is for Bz the Earth's center. In addition to this, we present results obtained at different locations on the Earth's surface. We choose equatorial locations at local noon, dusk (18:00 hours), midnight and dawn (6:00 hours). The different virtual observatory locations reveal the variation around the earth-centered Dst value resulting from the distribution of electric currents in the magnetosphere during different phases of a storm.

  9. Effect of a dc magnetic field on the magnetization relaxation of uniaxial single-domain ferromagnetic particles driven by a strong ac magnetic field

    International Nuclear Information System (INIS)

    Dejardin, Pierre-Michel; Kalmykov, Yuri P.

    2010-01-01

    The nonlinear ac stationary response of the magnetization of noninteracting uniaxial single-domain ferromagnetic particles acted on by superimposed dc and ac magnetic fields applied along the anisotropy axis is evaluated from the Fokker-Planck equation, expressed as an infinite hierarchy of recurrence equations for Fourier components of the relaxation functions governing longitudinal relaxation of the magnetization. The exact solution of this hierarchy comprises a matrix continued fraction, allowing one to evaluate the ac nonlinear response and reversal time of the magnetization. For weak ac fields, the results agree with perturbation theory. It is shown that the dc bias field changes substantially the magnetization dynamics leading to new nonlinear effects. In particular, it is demonstrated that for a nonzero bias field as the magnitude of the ac field increases the reversal time first increases and having attained its maximum at some critical value of the ac field, decreases exponentially.

  10. Photometric variability in a warm, strongly magnetic DQ white dwarf, SDSS J103655.39+652252.2

    International Nuclear Information System (INIS)

    Williams, Kurtis A.; Winget, D. E.; Montgomery, M. H.; Hermes, J. J.; Falcon, Ross E.; Winget, K. I.; Dufour, Patrick; Kepler, S. O.; Bolte, Michael; Rubin, Kate H. R.; Liebert, James

    2013-01-01

    We present the discovery of photometric variability in the DQ white dwarf SDSS J103655.39+652252.2 (SDSS J1036+6522). Time-series photometry reveals a coherent monoperiodic modulation at a period of 1115.64751(67) s with an amplitude 0.442% ± 0.024%; no other periodic modulations are observed with amplitudes ≳ 0.13%. The period, amplitude, and phase of this modulation are constant within errors over 16 months. The spectrum of SDSS J1036+6522 shows magnetic splitting of carbon lines, and we use Paschen-Back formalism to develop a grid of model atmospheres for mixed carbon and helium atmospheres. Our models, while reliant on several simplistic assumptions, nevertheless match the major spectral and photometric properties of the star with a self-consistent set of parameters: T eff ≈ 15, 500 K, log g ≈ 9, log (C/He) = –1.0, and a mean magnetic field strength of 3.0 ± 0.2 MG. The temperature and abundances strongly suggest that SDSS J1036+6522 is a transition object between the hot, carbon-dominated DQs and the cool, helium-dominated DQs. The variability of SDSS J1036+6522 has characteristics similar to those of the variable hot carbon-atmosphere white dwarfs (DQVs), however, its temperature is significantly cooler. The pulse profile of SDSS J1036+6522 is nearly sinusoidal, in contrast with the significantly asymmetric pulse shapes of the known magnetic DQVs. If the variability in SDSS J1036+6522 is due to the same mechanism as other DQVs, then the pulse shape is not a definitive diagnostic on the absence of a strong magnetic field in DQVs. It remains unclear whether the root cause of the variability in SDSS J1036+6522 and the other hot DQVs is the same.

  11. Magnetic resonance imaging study of cryptococcal neuroradiological lesions in HIV-negative cryptococcal meningitis.

    Science.gov (United States)

    Zhong, Y; Zhou, Z; Fang, X; Peng, F; Zhang, W

    2017-08-01

    Magnetic resonance (MR) scanning has become an important diagnostic and management tool in cryptococcal meningitis (CM). However, there are only isolated case reports documenting neuroradiological findings in human immunodeficiency virus (HIV)-negative patients with CM and none has clearly addressed the relationship between cerebral lesions on magnetic resonance imaging (MRI) and prognosis. The MR brain images available from 114 HIV-negative patients with CM were retrospectively analysed. Patients were divided into Group I with one or more CM-related lesions and Group II without CM-related lesions. Initial clinical and biochemical markers and prognosis were collected and compared between the two groups. In the present study, the most common pattern of CM-related lesions by MRI was radiological meningitis, following by Virchow-Robin (VR) dilatation, hydrocephalus, intracerebral nodules and pseudocysts, which was different from previous studies reporting that the main MR findings of cerebral cryptococcosis in HIV-infected patients include dilated VR spaces, masses and pseudocysts. Compared to the patients without CM-related lesions, patients with CM-related lesions presented with a higher percentage of male patients, a higher frequency of altered mental status, a higher positive rate of Cryptococcus culture in cerebrospinal fluid (CSF) and a lower ratio of CSF glucose/blood glucose. Poor outcomes were more frequent in patients with presence of CM-related lesions compared to patients without CM-related lesions. In conclusion, the main pattern of cryptococcosis-related lesions on MR scanning differ between non-HIV- and HIV-positive patients with CM. The presence of CM-related lesions was significantly associated with predictors for poor outcome. Neuroimaging on MR scanning is a useful tool to evaluate the initial severity and prognosis of CM without HIV infection.

  12. On the theory of stationary charged particle ensembles in strongly non-homogeneous azimuthally symmetric magnetic fields

    International Nuclear Information System (INIS)

    Auluck, S.K.H.

    1982-01-01

    A method of treating problems involving strongly nonadiabatic particle orbits in a magnetic field is described for the case when the system is long-lived on the collisional time scale. A canonical distribution P=Z -1 exp-β(H+Ωpsub(theta)) results from maximization of entropy subject to conservation of the Hamiltonian H and canonical angular momentum psub(theta) for an azimuthally symmetric system. By taking the MIGMA problem as an example, the method of determining the constants β,Ω,Z from the average energy, average angular momentum and the total number of particles is illustrated. Associated physical effects are discussed. (author)

  13. Global well-posedness and decay estimates of strong solutions to a two-phase model with magnetic field

    Science.gov (United States)

    Wen, Huanyao; Zhu, Limei

    2018-02-01

    In this paper, we consider the Cauchy problem for a two-phase model with magnetic field in three dimensions. The global existence and uniqueness of strong solution as well as the time decay estimates in H2 (R3) are obtained by introducing a new linearized system with respect to (nγ -n˜γ , n - n ˜ , P - P ˜ , u , H) for constants n ˜ ≥ 0 and P ˜ > 0, and doing some new a priori estimates in Sobolev Spaces to get the uniform upper bound of (n - n ˜ ,nγ -n˜γ) in H2 (R3) norm.

  14. Magnetic resonance imaging detection of prostate cancer in men with previous negative prostate biopsy.

    Science.gov (United States)

    Truong, Matthew; Frye, Thomas P

    2017-06-01

    Use of transrectal ultrasound guided systematic prostate biopsy has poor diagnostic accuracy for prostate cancer (PCa) detection. Recently multiparametric MRI (mpMRI) of the prostate and MR/US fusion biopsy has been gaining popularity for men who have previously undergone a negative biopsy. We performed PubMed ® and Web of Science ® searches to identify studies on this subject, particularly focusing on studies consisting of patients who have had at least one previously negative biopsy. Across the literature, when a suspicious lesion is found on mpMRI, MR/US fusion biopsy has consistently demonstrated higher detection rate for any PCa and clinically significant PCa (csPCa) compared to the traditional repeat systematic biopsy (SB) approach. Furthermore, anteriorly located tumors are frequently identified using MR targeted biopsy (TB), suggesting that an MR guided approach allows for increased accuracy for detecting tumors commonly missed by systematic biopsies. We conclude that men with a prior negative biopsy and continued suspicion of PCa should strongly be encouraged to get a prostate mpMRI prior to a repeat biopsy.

  15. Strong Transverse Photosphere Magnetic Fields and Twist in Light Bridge Dividing Delta Sunspot of Active Region 12673

    Science.gov (United States)

    Wang, Haimin; Yurchyshyn, Vasyl; Liu, Chang; Ahn, Kwangsu; Toriumi, Shin; Cao, Wenda

    2018-01-01

    Solar Active Region (AR) 12673 is the most flare productive AR in the solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that this region had an unusual high rate of flux emergence, while Huang et al. (2018) reported that the X9.3 flare had extremely strong white-light flare emissions. Yang at al. (2017) described the detailed morphological evolution of this AR. In this report, we focus on usual behaviors of the light bridge (LB) dividing the delta configuration of this AR, namely the strong magnetic fields (above 5500 G) in the LB and apparent photospheric twist as shown in observations with a 0.1 arcsec spatial resolution obtained by the 1.6m telescope at Big Bear Solar Observatory.

  16. Diffraction by a grating made of a uniaxial dielectric-magnetic medium exhibiting negative refraction

    Energy Technology Data Exchange (ETDEWEB)

    Depine, Ricardo A [Grupo de Electromagnetismo Aplicado, Departamento de FIsica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); Lakhtakia, Akhlesh [CATMAS-Computational and Theoretical Materials Sciences Group, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802-6812 (United States); Department of Physics, Imperial College, London SW7 2BZ (United Kingdom)

    2005-08-01

    Diffraction of linearly polarized plane electromagnetic waves at the periodically corrugated boundary of vacuum and a linear, homogeneous, uniaxial, dielectric-magnetic medium is formulated as a boundary-value problem and solved using the Rayleigh method. The focus is on situations where the diffracted fields maintain the same polarization state as the s- or p-polarized incident plane wave. Attention is paid to two classes of diffracting media: those with negative definite permittivity and permeability tensors, and those with indefinite permittivity and permeability tensors. For the situations investigated, whereas the dispersion equations in the diffracting medium turn out to be elliptic for the first class of diffracting media, they are hyperbolic for the second class. Examples are reported with the first class of diffracting media of instances when the grating acts either as a positively refracting interface or as a negatively refracting interface. For the second class of diffracting media, hyperbolic dispersion equations imply the possibility of an infinite number of refraction channels.

  17. Strong ion accelerating by collisionless magnetosonic shock wave propagating perpendicular to a magnetic field

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu.

    1984-12-01

    A 2-1/2 dimensional fully relativistic, fully electromagnetic particle code is used to study a time evolution of nonlinear magnetosonic pulse propagating in the direction perpendicular to a magnetic field. The pulse is excited by an instantaneous piston acceleration, and evolves totally self-consistently. Large amplitude pulse traps some ions and accelerates them parallel to the wave front. They are detrapped when their velocities become of the order of the sum of the ExB drift velocity and the wave phase velocity, where E is the electric field in the direction of wave propagation. The pulse develops into a quasi-shock wave in a collisionless plasma by a dissipation due to the resonant ion acceleration. Simple nonlinear wave theory for a cold plasma well describes the shock properties observed in the simulation except for the effects of resonant ions. In particular, magnitude of an electric potential across the shock region is derived analytically and is found to be in good agreement with our simulations. The potential jump is proportional to B 2 , and hence the ExB drift velocity of the trapped ions is proportional to B. (author)

  18. Faraday effect in rare-earth ferrite garnets located in strong magnetic fields

    International Nuclear Information System (INIS)

    Valiev, U.V.; Zvezdin, A.K.; Krinchik, G.S.; Levitin, R.Z.; Mukimov, K.M.; Popov, A.I.

    1983-01-01

    The Faraday effect is investigated experimentally in single crystal specimens of rare earth iron garnets (REIG) R 3 Fe 5 O 12 (R=Y, Gd, Tb, Dy, Er, Tm, Yb, Eu, Sm and Ho) and also in mixed iron garnets Rsub(x)Ysub(3-x)Fesub(5)Osub(12) (R=Tb, Dy). The m.easurements are carried out in pulsed magnetic fields of intensity up to 200 kOe, in a temperature range from 4.2 to 300 K and at a wavelength of the light lambda=1.15 μm. The field dependence of the Faraday effect observed in the REIG cannot be explained if only the usually considered ''paramagnetic'' contribution to the Faraday effect is taken into account. A theory is developed which, besides the paramagnetic mechanism, takes into account a diamagnetic mechanism and also the mixing of the wave functions of the ground and excited multiplets. The contributions of each of these three mechanisms to the angle of rotation of the plane of polarization by the rare earth sublattice of the iron garnet are estimated theoretically. It is concluded that the mixing mechanism contributes significantly to the field and temperature dependences of the Faraday effect in REIG

  19. Magnetism and local symmetry breaking in a Mott insulator with strong spin orbit interactions.

    Science.gov (United States)

    Lu, L; Song, M; Liu, W; Reyes, A P; Kuhns, P; Lee, H O; Fisher, I R; Mitrović, V F

    2017-02-09

    Study of the combined effects of strong electronic correlations with spin-orbit coupling (SOC) represents a central issue in quantum materials research. Predicting emergent properties represents a huge theoretical problem since the presence of SOC implies that the spin is not a good quantum number. Existing theories propose the emergence of a multitude of exotic quantum phases, distinguishable by either local point symmetry breaking or local spin expectation values, even in materials with simple cubic crystal structure such as Ba 2 NaOsO 6 . Experimental tests of these theories by local probes are highly sought for. Our local measurements designed to concurrently probe spin and orbital/lattice degrees of freedom of Ba 2 NaOsO 6 provide such tests. Here we show that a canted ferromagnetic phase which is preceded by local point symmetry breaking is stabilized at low temperatures, as predicted by quantum theories involving multipolar spin interactions.

  20. Strong perpendicular magnetic anisotropy at FeCoB/MgO interface with an ultrathin HfOx insertion layer

    Science.gov (United States)

    Ou, Yongxi; Ralph, Daniel; Buhrman, Robert

    The realization of robust perpendicular magnetic anisotropy (PMA) in heavy metal(HM)/FeCoB/MgO thin-film heterostructures has enabled a pathway for the implementation of high density memory elements based on perpendicularly magnetized tunnel junctions, and also provides a platform for the study and control of domain walls and of novel magnetic chiral structures such as skyrmions in nanowire structures. Here we report on the achievement of more robust PMA in Ta/FeCoB/MgO heterostructures by the insertion of an ultrathin HfOx passivation layer at the FeCoB/MgO interface. This is accomplished by depositing one to two atomic layers of Hf onto the FeCoB before the subsequent rf sputter deposition of the MgO layer, which fully oxidizes the Hf layer as confirmed by X-ray photoelectron spectroscopy measurements. The result is a strong interfacial perpendicular anisotropy energy density as large as 1.7 erg/cm-2 without any post-fabrication annealing treatment. Similar results have been achieved with the use of W and Pt HM base layers. This work broadens the class and enhances the capabilities of PMA HM/FM heterostructures for spintronics research and applications.

  1. A device to measure the effects of strong magnetic fields on the image resolution of PET scanners

    CERN Document Server

    Burdette, D; Chesi, E; Clinthorne, N H; Cochran, E; Honscheid, K; Huh, S S; Kagan, H; Knopp, M; Lacasta, C; Mikuz, M; Schmalbrock, P; Studen, A; Weilhammer, P

    2009-01-01

    Very high resolution images can be achieved in small animal PET systems utilizing solid state silicon pad detectors. As these systems approach sub-millimeter resolutions, the range of the positron is becoming the dominant contribution to image blur. The size of the positron range effect depends on the initial positron energy and hence the radioactive tracer used. For higher energy positron emitters, such as and , which are gaining importance in small animal studies, the width of the annihilation point distribution dominates the spatial resolution. This positron range effect can be reduced by embedding the field of view of the PET scanner in a strong magnetic field. In order to confirm this effect experimentally, we developed a high resolution PET instrument based on silicon pad detectors that can operate in a 7 T magnetic field. In this paper, we describe the instrument and present initial results of a study of the effects of magnetic fields up to 7 T on PET image resolution for and point sources.

  2. Performance and analysis of wireless power charging system from room temperature to HTS magnet via strong resonance coupling method

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Y. D.; Lee, S. Y.; Lee, T. W.; Kim, J. S. [Suwon Science College, Suwon (Korea, Republic of); Lee, C. Y. [Korea Railroad Institute, Uiwang (Korea, Republic of)

    2016-03-15

    The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.

  3. Test of Horizontal Magnetic Field Measurements in the Presence of a Strong Vertical Field

    CERN Document Server

    Vasserman, Isaac

    2004-01-01

    Trajectory straightness is an important parameter defining the performance of free-electron laser (FEL) devices. The first test of horizontal field measurements using Hall probes was done in 1998 as a preparation to the tuning of undulators for the FEL project at the Advanced Photon Source. This work continues the 1998 work, now associated with Linac Coherent Light Source (LCLS) project. Tolerances for the LCLS FEL undulator specify 2 um trajectory excursion in both (horizontal and vertical) planes for a particle energy of 14.1 GeV, which means that measurements of a small horizontal field in presence of strong (up to 1.5 T) vertical field are required. Hall probe measurements under such conditions are complicated due to a planar Hall probe effect. Previous tests done in 1998 showed that a 2- axis Sentron probe is a possible choice. The high sensitivity of horizontal field integrals to the vertical position of the sensor was observed. It was shown that this probe could be used for fast measurements and tuning...

  4. Effects of a strong magnetic field on internal gravity waves: trapping, phase mixing, reflection and dynamical chaos

    Science.gov (United States)

    Loi, Shyeh Tjing; Papaloizou, John C. B.

    2018-04-01

    The spectrum of oscillation modes of a star provides information not only about its material properties (e.g. mean density), but also its symmetries. Spherical symmetry can be broken by rotation and/or magnetic fields. It has been postulated that strong magnetic fields in the cores of some red giants are responsible for their anomalously weak dipole mode amplitudes (the "dipole dichotomy" problem), but a detailed understanding of how gravity waves interact with strong fields is thus far lacking. In this work, we attack the problem through a variety of analytical and numerical techniques, applied to a localised region centred on a null line of a confined axisymmetric magnetic field which is approximated as being cylindrically symmetric. We uncover a rich variety of phenomena that manifest when the field strength exceeds a critical value, beyond which the symmetry is drastically broken by the Lorentz force. When this threshold is reached, the spatial structure of the g-modes becomes heavily altered. The dynamics of wave packet propagation transitions from regular to chaotic, which is expected to fundamentally change the organisation of the mode spectrum. In addition, depending on their frequency and the orientation of field lines with respect to the stratification, waves impinging on different parts of the magnetised region are found to undergo either reflection or trapping. Trapping regions provide an avenue for energy loss through Alfvén wave phase mixing. Our results may find application in various astrophysical contexts, including the dipole dichotomy problem, the solar interior, and compact star oscillations.

  5. The search for negative amplitude components in quasi-continuous distributions of relaxation times: the example of 1H magnetization exchange in articular cartilage and hydrated collagen

    Science.gov (United States)

    Fantazzini, Paola; Galassi, Francesca; Bortolotti, Villiam; Brown, Robert J. S.; Vittur, Franco

    2011-06-01

    When inverting nuclear magnetic resonance relaxation data in order to obtain quasi-continuous distributions of relaxation times for fluids in porous media, it is common practice to impose a non-negative (NN) constraint on the distributions. While this approach can be useful in reducing the effects of data distortion and/or preventing wild oscillations in the distributions, it may give misleading results in the presence of real negative amplitude components. Here, some examples of valid negative components for articular cartilage and hydrated collagen are given. Articular cartilage is a connective tissue, consisting mainly of collagen, proteoglycans and water, which can be considered, in many aspects, as a porous medium. Separate T1 relaxation data are obtained for low-mobility ('solid') macromolecular 1H and for higher-mobility ('liquid') 1H by the separation of these components in free induction decays, with α denoting the solid/liquid 1H ratio. When quasi-continuous distributions of relaxation times (T1) of the solid and liquid signal components of cartilage or collagen are computed from experimental relaxation data without imposing the usual NN constraint, valid negative peaks may appear. The features of the distributions, in particular negative peaks, and the fact that peaks at longer times for macromolecular and water protons are at essentially the same T1, are interpreted as the result of a magnetization exchange between these two spin pools. For the only-slightly-hydrated collagen samples, with α>1, the exchange leads to small negative peaks at short T1 times for the macromolecular component. However, for the cartilage, with substantial hydration or for a strongly hydrated collagen sample, both with αLt1, the behavior is reversed, with a negative peak for water at short times. The validity of a negative peak may be accepted (dismissed) by a high (low) cost of NN in error of fit. Computed distributions for simulated data using observed signal

  6. Anomalously strong relaxation of the polarization of muons in the magnetically ordered and paramagnetic states of the TbMnO3 multiferroic

    Science.gov (United States)

    Andrievskii, D. S.; Vorob'ev, S. I.; Getalov, A. L.; Golovenchits, E. I.; Komarov, E. N.; Kotov, S. A.; Sanina, V. A.; Shcherbakov, G. V.

    2017-09-01

    An anomalously strong relaxation of the muon polarization in a magnetically ordered state in the TbMnO3 multiferroic has been revealed by the method below the μ SR Néel temperature (42 K). Such a relaxation is due to the muon channel of relaxation of the polarization and the interaction of the magnetic moment of the muon with inhomogeneities of the internal magnetic field of an ordered state in the form of a cycloid. Above the Néel temperature, beginning with temperatures depending on the applied magnetic field, a two-phase state has been revealed where one phase has an anomalously strong relaxation of the muon polarization for a paramagnetic state. These features of the paramagnetic state are due to short-range magnetic order domains that appear in strongly frustrated TbMnO3. A true paramagnetic state has been observed only at T ≥ 150 K.

  7. High-latitude dayside electric fields and currents during strong northward interplanetary magnetic field: Observations and model simulation

    International Nuclear Information System (INIS)

    Clauer, C.R.; Friis-Christensen, E.

    1988-01-01

    On July 23, 1983, the Interplanetary Magnetic Field turned strongly northward, becoming about 22 nT for several hours. Using a combined data set of ionospheric convection measurements made by the Sondre Stromfjord incoherent scatter radar and convection inferred from Greenland magnetometer measurements, we observe the onset of the reconfiguration of the high-latitude ionospheric currents to occur about 3 min following the northward IMF encountering the magnetopause. The large-scale reconfiguration of currents, however, appears to evolve over a period of about 22 min. Using a computer model in which the distribution of field-aligned current in the polar cleft is directly determined by the strength and orientation of the interplanetary electric field, we are able to simulate the time-varying pattern of ionospheric convection, including the onset of high-latitude ''reversed convection'' cells observed to form during the interval of strong northward IMF. These observations and the simulation results indicate that the dayside polar cap electric field observed during strong northward IMF is produced by a direct electrical current coupling with the solar wind. copyright American Geophysical Union 1988

  8. Study of Muon Triggers and Momentum Reconstruction in a Strong Magnetic Field for a Muon Detector at LHC

    CERN Multimedia

    2002-01-01

    % RD-5 \\\\ \\\\ A small fraction of a muon detector for possible use in an LHC experiment is installed in the SPS H2 beam. It consists of a 3T superconducting solenoid enclosing a 10$\\lambda$ deep calorimeter made of stainless steel plates interleaved with Honeycomb strip chambers. Behind this magnet are located 3 muon stations for triggering and momentum measurement. These stations, consisting of UA1 muon chambers backed up with Resistive Plate Chambers (RPC), are inserted in a 1.5~T absorber magnet of 20$\\lambda$ total thickness, station 2 being located after 10$\\lambda$. \\\\ \\\\During the data taking period (1991-1994) 10$^{7}$ muon and hadron events were recorded. Beams of negative muons and pions and of positive muons and hadrons $ (\\pi^+, K ^+ $ and protons) were used with a momentum ranging from 10~to~300~GeV/c. \\\\ \\\\The RD-5 program has covered several topics related to muon detection at LHC: \\\\ \\\\\\begin{description} \\item[(i)]~~study of the behaviour of muons from hadron punchthrough and decays, and also ...

  9. Fibrous polymer grafted magnetic chitosan beads with strong poly(cation-exchange) groups for single step purification of lysozyme.

    Science.gov (United States)

    Bayramoglu, Gulay; Tekinay, Turgay; Ozalp, V Cengiz; Arica, M Yakup

    2015-05-15

    Lysozyme is an important polypetide used in medical and food applications. We report a novel magnetic strong cation exchange beads for efficient purification of lysozyme from chicken egg white. Magnetic chitosan (MCHT) beads were synthesized via phase inversion method, and then grafted with poly(glycidyl methacrylate) (p(GMA)) via the surface-initiated atom transfer radical polymerization (SI-ATRP). Epoxy groups of the grafted polymer, were modified into strong cation-exchange groups (i.e., sulfonate groups) in the presence of sodium sulfite. The MCTH and MCTH-g-p(GMA)-SO3H beads were characterized by ATR-FTIR, SEM, and VSM. The sulphonate groups content of the modified MCTH-g-p(GMA)-4 beads was found to be 0.53mmolg(-1) of beads by the potentiometric titration method. The MCTH-g-p(GMA)-SO3H beads were first used as an ion-exchange support for adsorption of lysozyme from aqueous solution. The influence of different experimental parameters such as pH, contact time, and temperature on the adsorption process was evaluated. The maximum adsorption capacity was found to be 208.7mgg(-1) beads. Adsorption of lysozyme on the MCTH-g-p(GMA)-SO3H beads fitted to Langmuir isotherm model and followed the pseudo second-order kinetic. More than 93% of the adsorbed lysozyme was desorbed using Na2CO3 solution (pH 11.0). The purity of the lysozyme was checked by HPLC and SDS gel electrophoresis. In addition, the MCTH-g-p(GMA)-SO3H beads prepared in this work showed promising potential for separation of various anionic molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. He 2++ molecular ion in a strong time-dependent magnetic field: a current-density functional study.

    Science.gov (United States)

    Vikas

    2011-08-01

    The He 2++ molecular ion exposed to a strong ultrashort time-dependent (TD) magnetic field of the order of 10(9) G is investigated through a quantum fluid dynamics (QFD) and current-density functional theory (CDFT) based approach using vector exchange-correlation (XC) potential and energy density functional that depend not only on the electronic charge-density but also on the current density. The TD-QFD-CDFT computations are performed in a parallel internuclear-axis and magnetic field-axis configuration at the field-free equilibrium internuclear separation R = 1.3 au with the field-strength varying between 0 and 10(11) G. The TD behavior of the exchange- and correlation energy of the He 2++ is analyzed and compared with that obtained using a [B-TD-QFD-density functional theory (DFT)] approach based on the conventional TD-DFT under similar computational constraints but using only scalar XC potential and energy density functional dependent on the electronic charge-density alone. The CDFT based approach yields TD exchange- and correlation energy and TD electronic charge-density significantly different from that obtained using the conventional TD-DFT based approach, particularly, at typical magnetic field strengths and during a typical time period of the TD field. This peculiar behavior of the CDFT-based approach is traced to the TD current-density dependent vector XC potential, which can induce nonadiabatic effects causing retardation of the oscillating electronic charge density. Such dissipative electron dynamics of the He 2++ molecular ion is elucidated by treating electronic charge density as an electron-"fluid" in the terminology of QFD. Copyright © 2011 Wiley Periodicals, Inc.

  11. Unusual negative magnetoresistance in Bi2Se3-ySy topological insulator under perpendicular magnetic field

    Science.gov (United States)

    Singh, Rahul; Gangwar, Vinod K.; Daga, D. D.; Singh, Abhishek; Ghosh, A. K.; Kumar, Manoranjan; Lakhani, A.; Singh, Rajeev; Chatterjee, Sandip

    2018-03-01

    The magneto-transport properties of Bi2Se3-ySy were investigated. Magnetoresistance (MR) decreases with an increase in the S content, and finally, for 7% (i.e., y = 0.21) S doping, the magnetoresistance becomes negative. This negative MR is unusual as it is observed when a magnetic field is applied in the perpendicular direction to the plane of the sample. The magneto-transport behavior shows the Shubnikov-de Haas (SdH) oscillation, indicating the coexistence of surface and bulk states. The negative MR has been attributed to the non-trivial bulk conduction.

  12. Quasilongitudinal soliton in a two-dimensional strongly coupled complex dusty plasma in the presence of an external magnetic field.

    Science.gov (United States)

    Ghosh, Samiran

    2014-09-01

    The propagation of a nonlinear low-frequency mode in two-dimensional (2D) monolayer hexagonal dusty plasma crystal in presence of external magnetic field and dust-neutral collision is investigated. The standard perturbative approach leads to a 2D Korteweg-de Vries (KdV) soliton for the well-known dust-lattice mode. However, the Coriolis force due to crystal rotation and Lorentz force due to magnetic field on dust particles introduce a linear forcing term, whereas dust-neutral drag introduce the usual damping term in the 2D KdV equation. This new nonlinear equation is solved both analytically and numerically to show the competition between the linear forcing and damping in the formation of quasilongitudinal soliton in a 2D strongly coupled complex (dusty) plasma. Numerical simulation on the basis of the typical experimental plasma parameters and the analytical solution reveal that the neutral drag force is responsible for the usual exponential decay of the soliton, whereas Coriolis and/or Lorentz force is responsible for the algebraic decay as well as the oscillating tail formation of the soliton. The results are discussed in the context of the plasma crystal experiment.

  13. Impact of a Strong Magnetic Storm and Two X-Ray Flares on the Ionospheric HF Channel in the Summer Solstice of 2015 According to Oblique Sounding in the Eurasian Region

    Science.gov (United States)

    Uryadov, V. P.; Kolchev, A. A.; Vertogradov, G. G.; Vybornov, F. I.; Egoshin, I. A.; Sklyarevsky, M. S.; Shumaev, V. V.; Chernov, A. G.

    2017-10-01

    We present the results of observations of the impact a strong magnetic storm and two X-ray flares in the summer solstice of 2015 on the HF signal characteristics during oblique sounding of the ionosphere in the Eurasian region. It was found that the negative phase of the magnetic storm led to a strong degradation of the ionospheric channel, up to a long blackout on the paths adjacent to the subauroral latitudes. On the midlatitude paths, a decrease in the maximum observable frequency of the F layer reached 50% with respect to the average values for an undisturbed ionosphere. The propagation velocity of the negative phase of a disturbance from the subauroral to the midlatitude ionosphere is determined (it is equal to about 100 m/s). It is shown that during a magnetic storm the least observable frequency and the average signal-to-noise ratio for the propagation mode via the sporadic E s layer correlate well with the auroral AE index. Anomalous signals were detected in the main phase of the magnetic storm on the Cyprus—Rostov-on-Don path when a chirp ionosonde-radio direction finder was operated in the over-the-horizon HF radar mode. On the basis of modeling and comparison with experimental data, it is shown that the anomalous signals are due to scattering of radio waves by small-scale irregularities located in the subauroral ionospheric F region.

  14. Toxicity evaluation of magnetic hyperthermia induced by remote actuation of magnetic nanoparticles in 3D micrometastasic tumor tissue analogs for triple negative breast cancer.

    Science.gov (United States)

    Stocke, Nathanael A; Sethi, Pallavi; Jyoti, Amar; Chan, Ryan; Arnold, Susanne M; Hilt, J Zach; Upreti, Meenakshi

    2017-03-01

    Magnetic hyperthermia as a treatment modality is acquiring increased recognition for loco-regional therapy of primary and metastatic lung malignancies by pulmonary delivery of magnetic nanoparticles (MNP). The unique characteristic of magnetic nanoparticles to induce localized hyperthermia in the presence of an alternating magnetic field (AMF) allows for preferential killing of cells at the tumor site. In this study we demonstrate the effect of hyperthermia induced by low and high dose of MNP under the influence of an AMF using 3D tumor tissue analogs (TTA) representing the micrometastatic, perfusion independent stage of triple negative breast cancer (TNBC) that infiltrates the lungs. While application of inhalable magnetic nanocomposite microparticles or magnetic nanocomposites (MnMs) to the micrometastatic TNBC model comprised of TTA generated from cancer and stromal cells, showed no measureable adverse effects in the absence of AMF-exposure, magnetic hyperthermia generated under the influence of an AMF in TTA incubated in a high concentration of MNP (1 mg/mL) caused significant increase in cellular death/damage with mechanical disintegration and release of cell debris indicating the potential of these inhalable composites as a promising approach for thermal treatment of diseased lungs. The novelty and significance of this study lies in the development of methods to evaluate in vitro the application of inhalable composites containing MNPs in thermal therapy using a physiologically relevant metastatic TNBC model representative of the microenvironmental characteristics in secondary lung malignancies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Quark matter and quark stars in strong magnetic fields at finite temperature within the confined-isospin-density-dependent mass model

    Science.gov (United States)

    Chu, Peng-Cheng; Li, Xiao-Hua; Ma, Hong-Yang; Wang, Bin; Dong, Yu-Min; Zhang, Xiao-Min

    2018-03-01

    We study the properties of strange quark matter (SQM) and quark stars (QSs) in strong magnetic fields within the extended confined isospin-density-dependent mass (CIDDM) model including the temperature dependence of the equivalent mass for quarks. The quark symmetry energy, quark symmetry free energy, and the equation of state (EOS) of SQM in constant magnetic fields at finite temperature are investigated, and it is found that including the temperature dependence in CIDDM model and considering strong magnetic fields can both significantly influence the properties of the SQM and the maximum mass of quark stars. Using the density-dependent magnetic field and assuming two extreme cases for the magnetic field orientation in QSs (the radial orientation in which the local magnetic fields are along the radial direction and the transverse orientation in which the local magnetic fields are randomly oriented but perpendicular to the radial orientation), we analyze the mass-radius relations for different stages of the protoquark stars (PQSs) along the star evolution. Our results indicate that the maximum mass of magnetized PQSs may depend on not only the strength distribution and the orientation of the magnetic fields inside the PQSs, but also the heating process and the cooling process in the star evolution.

  16. Multiparametric magnetic resonance imaging predicts the presence of prostate cancer in patients with negative prostate biopsy.

    Science.gov (United States)

    Lista, F; Castillo, E; Gimbernat, H; Rodríguez-Barbero, J M; Panizo, J; Angulo, J C

    2015-03-01

    To assess the ability of multiparametric prostate magnetic resonance imaging (mpMRI) to detect prostate cancer in patients with prior negative transrectal prostate biopsy (TPB). mpMRI (TSE-T2-w, DWI and DCE sequences) was performed on 1.5T (Magnetom Avanto; Siemens Healthcare Solutions) in 150 patients suspicious of prostate cancer and with negative TPB. European Society of Urogenital Radiology (ESUR) criteria were used (score 1: clinically significant disease is highly unlikely to be present; score 2: clinically significant cancer is unlikely to be present; score 3: clinically significant cancer is equivocal; score 4: clinically significant cancer is likely to be present; score 5: clinically significant cancer is highly likely to be present). PSA measurement (total and free), digital rectal examination (DRE), transrectal ultrasound (TRU) and a second TPB (at least 14 cylinders) were performed in all patients. Variables were submitted for independent blind analysis. The accuracy of each test was measured. Stepwise selection model for prediction of prostate cancer in second TPB was developed. Mean age was 66.2± 5 years (51-77), mean PSA 11.3± 9.6ng/mL (0.9-75) and mean prostatic volume 82.2±42 (20-250) cc. DRE was suspicious in 11 (7.3%) patients. The mean number of cylinders per patient sampled in second TRB was 17.6±2.7(14-22). Second TRB was positive in 28 patients (18.7%). mpMRI was positive (score 3-5) in 102 (68%), test sensibility was 92.9% and the NPV was 95.8%. The risk of prostate cancer diagnosis in second TPB is modified by: PSA velocity > 0.75 (OR 1.04 [0.99-1.08]; P=0.06), free/total ratio PSA <15% (OR 0.37 [0.13-1.05]; P=0.06), each cc. of prostate volume (OR 0.98 [0.97-1]; P=0.017) and mpMRI 3-5 (OR 7.87 [1.78-34.7]; P=0.006). Multivariate analysis reveals that mpMRI (OR 7.41 [1.65-33.28]; P=0.009) and prostatic volume (OR 0.31 [0.12-0.78]; P=0.01) are independent risk predictors of prostate cancer. According to ESUR guidelines and in patients

  17. Validation of numerical solvers for liquid metal flow in a complex geometry in the presence of a strong magnetic field

    Science.gov (United States)

    Patel, Anita; Pulugundla, Gautam; Smolentsev, Sergey; Abdou, Mohamed; Bhattacharyay, Rajendraprasad

    2018-04-01

    Following the magnetohydrodynamic (MHD) code validation and verification proposal by Smolentsev et al. (Fusion Eng Des 100:65-72, 2015), we perform code to code and code to experiment comparisons between two computational solvers, FLUIDYN and HIMAG, which are presently considered as two of the prospective CFD tools for fusion blanket applications. In such applications, an electrically conducting breeder/coolant circulates in the blanket ducts in the presence of a strong plasma-confining magnetic field at high Hartmann numbers, it{Ha} (it{Ha}^2 is the ratio between electromagnetic and viscous forces) and high interaction parameters, it{N} (it{N} is the ratio of electromagnetic to inertial forces). The main objective of this paper is to provide the scientific and engineering community with common references to assist fusion researchers in the selection of adequate computational means to be used for blanket design and analysis. As an initial validation case, the two codes are applied to the classic problem of a laminar fully developed MHD flows in a rectangular duct. Both codes demonstrate a very good agreement with the analytical solution for it{Ha} up to 15, 000. To address the capabilities of the two codes to properly resolve complex geometry flows, we consider a case of three-dimensional developing MHD flow in a geometry comprising of a series of interconnected electrically conducting rectangular ducts. The computed electric potential distributions for two flows (Case A) it{Ha}=515, it{N}=3.2 and (Case B) it{Ha}=2059, it{N}=63.8 are in very good agreement with the experimental data, while the comparisons for the MHD pressure drop are still unsatisfactory. To better interpret the observed differences, the obtained numerical data are analyzed against earlier theoretical and experimental studies for flows that involve changes in the relative orientation between the flow and the magnetic field.

  18. Strong magnetism observed in carbon nanoparticles produced by the laser vaporization of a carbon pellet in hydrogen-containing Ar balance gas.

    Science.gov (United States)

    Asano, Hirohito; Muraki, Susumu; Endo, Hiroki; Bandow, Shunji; Iijima, Sumio

    2010-08-25

    Nanometer-scale carbon particles driven by the pulsed-laser vaporization of pelletized pure carbon powder at 1000 °C in a hydrogen-containing environment show anomalous magnetism like a superparamagnet, while the sample prepared in 100% of Ar does not show such magnetism. The observed magnetism was unchanged over months in the ambient. The structure of this nanomaterial resembles the foam of a laundry detergent and transmission electron microscopy indicates a clear corrugated line contrast. On the other hand, a sample without strong magnetism does not give such an image contrast. The x-ray diffraction pattern coincides with that of graphite and no other peak is detected. Thermogravimetry indicates that all samples completely burn out up to approx. 820 °C and no material remains after combustion, indicating that the sample does not contain impurity metals. Magnetization is easily saturated by ∼10,000 G at 280 K with no hysteresis, but the hysteresis appears at 4.2 K. This phenomenon is explained by introducing a crystalline anisotropy which restricts the motion of the magnetic moment and stabilizes the remnant magnetization at zero magnetic field. Magnitudes of the saturation magnetization are in the range of 1-5 emu G g(-1) at 4.2 K, which correspond to 0.002-0.01 Bohr magneton per carbon atom. This concentration may be increased by ten times or more, because only about 4-10% of particles have a magnetic domain in the present samples.

  19. Strong magnetism observed in carbon nanoparticles produced by the laser vaporization of a carbon pellet in hydrogen-containing Ar balance gas

    Energy Technology Data Exchange (ETDEWEB)

    Asano, Hirohito; Muraki, Susumu; Endo, Hiroki; Bandow, Shunji; Iijima, Sumio, E-mail: bandow@meijo-u.ac.j [Department of Materials Science and Engineering, Meijo University, 1-501 Shiogamaguchi, Tenpaku, Nagoya 468-8502 (Japan)

    2010-08-25

    Nanometer-scale carbon particles driven by the pulsed-laser vaporization of pelletized pure carbon powder at 1000 {sup 0}C in a hydrogen-containing environment show anomalous magnetism like a superparamagnet, while the sample prepared in 100% of Ar does not show such magnetism. The observed magnetism was unchanged over months in the ambient. The structure of this nanomaterial resembles the foam of a laundry detergent and transmission electron microscopy indicates a clear corrugated line contrast. On the other hand, a sample without strong magnetism does not give such an image contrast. The x-ray diffraction pattern coincides with that of graphite and no other peak is detected. Thermogravimetry indicates that all samples completely burn out up to approx. 820 {sup 0}C and no material remains after combustion, indicating that the sample does not contain impurity metals. Magnetization is easily saturated by {approx} 10 000 G at 280 K with no hysteresis, but the hysteresis appears at 4.2 K. This phenomenon is explained by introducing a crystalline anisotropy which restricts the motion of the magnetic moment and stabilizes the remnant magnetization at zero magnetic field. Magnitudes of the saturation magnetization are in the range of 1-5 emu G g{sup -1} at 4.2 K, which correspond to 0.002-0.01 Bohr magneton per carbon atom. This concentration may be increased by ten times or more, because only about 4-10% of particles have a magnetic domain in the present samples.

  20. Magnetic moment for the negative parity Λ→Σ0 transition in light cone QCD sum rules

    Directory of Open Access Journals (Sweden)

    T.M. Aliev

    2016-07-01

    Full Text Available The magnetic moment of the Λ→Σ0 transition between negative parity baryons is calculated in framework of the QCD sum rules approach by using the general form of the interpolating currents. The pollution arising from the positive-to-positive, and positive-to-negative parity baryons is eliminated by constructing the sum rules for different Lorentz structures. A comparison of our result with the predictions of the results of other approaches for the positive parity baryons is presented.

  1. Progress on The GEMS (Gravity Electro-Magnetism-Strong) Theory of Field Unification and Its Application to Space Problems

    International Nuclear Information System (INIS)

    Brandenburg, J. E.

    2008-01-01

    Progress on the GEMS (Gravity Electro-Magnetism-Strong), theory is presented as well as its application to space problems. The GEMS theory is now validated through the Standard Model of physics. Derivation of the value of the Gravitation constant based on the observed variation of α with energy: results in the formula G congruent with (ℎ/2π)c/M ηc 2 exp(-1/(1.61α)), where α is the fine structure constant,(ℎ/2π), is Planck's constant, c, is the speed of light, and M ηc is the mass of the η cc Charmonium meson that is shown to be identical to that derived from the GEM postulates. Covariant formulation of the GEM theory is now possible through definition of the spacetime metric tensor as a portion of the EM stress tensor normalized by its own trace: g ab = 4(F c a F cb )/(F ab F ab ), it is found that this results in a massless ground state vacuum and a Newtonian gravitation potential φ = 1/2 E 2 /B 2 . It is also found that a Lorentz or flat-space metric is recovered in the limit of a full spectrum ZPF

  2. Surface-termination-dependent magnetism and strong perpendicular magnetocrystalline anisotropy of an FeRh(001) thin film

    Czech Academy of Sciences Publication Activity Database

    Jekal, S.; Rhim, S.H.; Hong, S.C.; Son, W.-J.; Shick, Alexander

    2015-01-01

    Roč. 92, č. 6 (2015), " 064410-1"-" 064410-6" ISSN 1098-0121 R&D Projects: GA ČR GA15-07172S Institutional support: RVO:68378271 Keywords : magnetic anisotropy * magnetic recording * surface science Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  3. Monocytes isolated by positive and negative magnetic sorting techniques show different molecular characteristics and immunophenotypic behaviour [version 3; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Jashdeep Bhattacharjee

    2018-03-01

    Full Text Available Background: Magnetic sorting of cells, based on  microbead conjugated antibodies (Abs, employs positive as well as negative immunomagnetic separation methods, for isolation of a specific cell population. These microbeads are suggested to be nontoxic, biodegradable carriers conjugated to various antibodies. Isolation of cells through positive selection involves the attachment of antibody conjugated microbeads to the cells of interest, followed by their isolation in the presence of a strong magnetic field to obtain higher purity. Negative selection involves attachment of microbead conjugated antibodies to all other cell populations except the cells of interest, which remain untagged. In the present study, we compared the two methods for their effect on functional and immunophenotypic behavior of isolated CD14+ monocytes. Methods: Peripheral blood mononuclear cells (PBMCs were isolated from blood collected from healthy volunteers by density gradient centrifugation. Human blood derived monocytes were isolated through positive selection and negative selection, making use of the appropriate monocyte isolation kit. Monocytes were then stimulated with lipopolysaccharide (LPS and their activation and proliferation capacity were examined. The degradation or dissociation of cell-bound microbeads was also investigated. Results: We observed an impaired LPS sensitivity as well as poor activation and proliferation capacity upon stimulation by LPS in positively sorted CD14+ monocytes as compared to negatively sorted CD14+ monocytes. The attached microbeads did not degrade and remained attached to the cells even after 6 days of culture. Conclusions: Our results suggest that positively sorted CD14+ cells exhibit hampered functionality and may result in inaccurate analysis and observations in downstream applications. However, these cells can be used for immediate analytical procedures.

  4. Bubble Formation within Filaments of Melt-Processed Bi2212 wires and its strongly negative effect on the Critical Current Density

    CERN Document Server

    Kametani, F; Jiang, J; Scheuerlein, C; Malagoli, A; Di Michiel, M; Huang, Y; Miao, H; Parrell, J A; Hellstrom, E E; Larbalestier, D C

    2011-01-01

    Most studies of Bi2Sr2CaCu2Ox (Bi2212) show that the critical current density Jc is limited by the connectivity of the filaments, but what determines the connectivity is still elusive. Here we report on the role played by filament porosity in limiting Jc. By a microstructural investigation of wires quenched from the melt state, we find that porosity in the unreacted wire agglomerates into bubbles that segment the Bi2212 melt within the filaments into discrete sections. These bubbles do not disappear during subsequent processing because they are only partially filled by Bi2212 grains as the Bi2212 forms on cooling. Correlating the microstructure of quenched wires to their final, fully processed Jc values shows an inverse relation between Jc and bubble density. Bubbles are variable between conductors and perhaps from sample to sample, but they occur frequently and almost completely fill the filament diameter, so they exert a strongly variable but always negative effect on Jc. Bubbles reduce the continuous Bi221...

  5. Three-dimensional visualization of magnetic domain structure with strong uniaxial anisotropy via scanning hard X-ray microtomography

    Science.gov (United States)

    Suzuki, Motohiro; Kim, Kab-Jin; Kim, Sanghoon; Yoshikawa, Hiroki; Tono, Takayuki; Yamada, Kihiro T.; Taniguchi, Takuya; Mizuno, Hayato; Oda, Kent; Ishibashi, Mio; Hirata, Yuushou; Li, Tian; Tsukamoto, Arata; Chiba, Daichi; Ono, Teruo

    2018-03-01

    An X-ray tomographic technique was developed to investigate the internal magnetic domain structure in a micrometer-sized ferromagnetic sample. The technique is based on a scanning hard X-ray nanoprobe using X-ray magnetic circular dichroism (XMCD). From transmission XMCD images at the Gd L3 edge as a function of the sample rotation angle, the three-dimensional (3D) distribution of a single component of the magnetic vector in a GdFeCo microdisc was reconstructed with a spatial resolution of 360 nm, using a modified algebraic reconstruction algorithm. The method is applicable to practical magnetic materials and can be extended to 3D visualization of the magnetic domain formation process under external magnetic fields.

  6. EBSD Study on the Effect of a Strong Axial Magnetic Field on the Microstructure and Crystallography of Al-Ni Alloys During Solidification

    Science.gov (United States)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Moreau, Rene; Du, Dafan; Ren, Zhongming; Lu, Xionggang

    2016-03-01

    The effect of a strong magnetic field on the microstructure and crystallography of the primary and eutectic Al3Ni phases in Al-Ni alloys was investigated by using EBSD. The results show that the magnetic field significantly affected the microstructures and crystallography during both volume and directional solidification. As a result, the Al3Ni primary phases were aligned with the crystal direction along the magnetic field and formed a layer-like structure. The magnetic field intensity, solidification temperature, growth speed, and alloy composition played important roles during the alignment process of the Al3Ni primary phase. Indeed, the alignment degree increased with the magnetic field and the solidification temperature during normal solidification. Moreover, the effect of the magnetic field on the crystallography of the Al-Al3Ni eutectic in the Al-Ni alloys was also studied. The applied magnetic field modified the orientation of the preferred growth direction of the Al3Ni eutectic fiber and the crystallographic orientation relationship of the Al-Al3Ni eutectic. The orientation of the preferred growth direction of the Al3Ni eutectic fiber depended mainly on the solidification direction and the alignment of the Al3Ni primary phase. Furthermore, a method for controlling the crystallization process by adjusting the angle between the solidification direction and the magnetic field was proposed.

  7. Electron spin resonance and nuclear magnetic resonance of sodium macrostructures in strongly irradiated NaCl-K crystals: Manifestation of quasi-one-dimensional behavior of electrons

    NARCIS (Netherlands)

    Cherkasov, FG; Mustafin, RG; L'vov, SG; Denisenko, GA; den Hartog, HW; Vainshtein, D. I.

    1998-01-01

    Data from an investigation of electron spin resonance and nuclear magnetic resonance of NaCl-K (similar to 1 mole%) crystals strongly irradiated with electrons imply the observation of a metal-insulator transition with decreasing temperature and the manifestation of quasi-one-dimensional electron

  8. Nanoparticle targeting of Gram-positive and Gram-negative bacteria for magnetic-based separations of bacterial pathogens

    Science.gov (United States)

    Lu, Hoang D.; Yang, Shirley S.; Wilson, Brian K.; McManus, Simon A.; Chen, Christopher V. H.-H.; Prud'homme, Robert K.

    2017-04-01

    Antimicrobial resistance is a healthcare problem of increasing significance, and there is increasing interest in developing new tools to address bacterial infections. Bacteria-targeting nanoparticles hold promise to improve drug efficacy, compliance, and safety. In addition, nanoparticles can also be used for novel applications, such as bacterial imaging or bioseperations. We here present the use of a scalable block-copolymer-directed self-assembly process, Flash NanoPrecipitation, to form zinc(II)-bis(dipicolylamine) modified nanoparticles that bind to both Gram-positive and Gram-negative bacteria with specificity. Particles have tunable surface ligand densities that change particle avidity and binding efficacy. A variety of materials can be encapsulated into the core of the particles, such as optical dyes or iron oxide colloids, to produce imageable and magnetically active bacterial targeting constructs. As a proof-of-concept, these particles are used to bind and separate bacteria from solution in a magnetic column. Magnetic manipulation and separation would translate to a platform for pathogen identification or removal. These magnetic and targeted nanoparticles enable new methods to address bacterial infections.

  9. Negatively Charged and Dark Excitons in CsPbBr3 Perovskite Nanocrystals Revealed by High Magnetic Fields.

    Science.gov (United States)

    Canneson, Damien; Shornikova, Elena V; Yakovlev, Dmitri R; Rogge, Tobias; Mitioglu, Anatolie A; Ballottin, Mariana V; Christianen, Peter C M; Lhuillier, Emmanuel; Bayer, Manfred; Biadala, Louis

    2017-10-11

    The optical properties of colloidal cesium lead halide perovskite (CsPbBr 3 ) nanocrystals are examined by time-resolved and polarization-resolved spectroscopy in high magnetic fields up to 30 T. We unambiguously show that at cryogenic temperatures the emission is dominated by recombination of negatively charged excitons with radiative decay time of 300 ps. The additional long-lived emission, which decay time shortens from 40 down to 8 ns and in which the decay time shortens and relative amplitude increases in high magnetic fields, evidences the presence of a dark exciton. We evaluate g-factors of the bright exciton g X = +2.4, the electron g e = +2.18, and the hole g h = -0.22.

  10. Rotationally modulated variability and pulsations of the He-rich star CPD -62°2124 with an extraordinarily strong magnetic field

    Science.gov (United States)

    Hubrig, S.; Mikulášek, Z.; Kholtygin, A. F.; Ilyin, I.; Schöller, M.; Järvinen, S. P.; Scholz, R.-D.; Zejda, M.

    2017-11-01

    A longitudinal magnetic field with a strength of 5.2 kG was recently detected in CPD -62°2124, which has a fractional main-sequence lifetime of about 60 per cent. Strongly magnetic early-B type chemically peculiar stars in an advanced evolutionary state are of special interest to understand the evolution of the angular momentum and spin-down time-scales in the presence of a global magnetic field. We made use of 17 FORS 2 low-resolution spectropolarimetric observations and 844 ASAS3 photometric measurements for the determination of the rotation period, pulsationsand the magnetic field geometry of the star. We calculated periodograms and applied phenomenological models of photometric, spectral and spectropolarimetric variability. We found that all quantities studied, specifically equivalent widths, the mean longitudinal magnetic field 〈Bz〉 and the flux in the V filter, vary with the same period P = 2.628 d, which was identified as the rotation period. The observed variations can be fully explained by a rigidly rotating main-sequence star with an uneven distribution of chemical elements, photometric spots and a stable, nearly dipolar magnetic field with a polar field strength of about 21 kG, frozen into the body of the star. The magnetic field of CPD -62°2124 is tilted to the rotation axis by β = 28° ± 7°, while the inclination of the rotation axis towards the line of sight is only i = 20° ± 5°. In the acquired FORS 2 spectra, we detect short-term line profile variations indicating the presence of β Cephei type pulsations. As of today, no other pulsating star of this type is known to possess such a strong magnetic field.

  11. Negative magnetization and the tunable exchange bias field in LaCr{sub 0.8}Mn{sub 0.2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bora, Tribedi; Ravi, S., E-mail: sravi@iitg.ernet.in

    2014-05-01

    Manganese substituted Lanthanum chromite LaCr{sub 0.8}Mn{sub 0.2}O{sub 3} exhibits negative magnetization with decrease in temperature under the field cooled (FC) condition for the applied field H≤2000 Oe. The maximum magnetic compensation temperature, (T{sub comp}) was 147 K. A reentrant positive magnetization was observed at T≤50 K due to low temperature transition. The negative magnetization is explained by considering the paramagnetic moment of Mn ions under the influence of negative internal field. Measurement of magnetic hysteresis loops under FC condition shows the presence of exchange bias field at Tmagnetization reversal (negative magnetization) with the maximum magnetic compensation (M=0) temperature, and T{sub comp} =147 K. In addition to that the sample exhibits tunable exchange bias phenomenon at Tmagnetization is also observed. • The observed negative magnetization is explained by considering the paramagnetic moment of doped Mn ions under the influence of negative internal field. • The magnitude of exchange bias field is found to increase with decrease in cooling field. The origin of exchange bias field is explained in terms of anisotropic exchange interaction between the canted ferromagnetic component of Cr{sup 3+} ions and the paramagnetic component of Mn{sup 3+} ions under the negative internal field.

  12. Broad self-trapped and slow light bands based on negative refraction and interference of magnetic coupled modes

    Science.gov (United States)

    Fang, Yun-tuan; Ni, Zhi-yao; Zhu, Na; Zhou, Jun

    2016-01-01

    We propose a new mechanism to achieve light localization and slow light. Through the study on the coupling of two magnetic surface modes, we find a special convex band that takes on a negative refraction effect. The negative refraction results in an energy flow concellation effect from two degenerated modes on the convex band. The energy flow concellation effect leads to forming of the self-trapped and slow light bands. In the self-trapped band light is localized around the source without reflection wall in the waveguide direction, whereas in the slow light band, light becomes the standing-waves and moving standing-waves at the center and the two sides of the waveguide, respectively.

  13. Commensurability oscillations in a quasi-two-dimensional electron gas subject to strong in-plane magnetic field

    Czech Academy of Sciences Publication Activity Database

    Smrčka, Ludvík

    2016-01-01

    Roč. 77, Mar (2016), s. 108-113 ISSN 1386-9477 Institutional support: RVO:68378271 Keywords : lateral superlattices * commensurability oscillations * in-plane magnetic field Subject RIV: BE - Theoretical Physics Impact factor: 2.221, year: 2016

  14. Ce3 - xMgxCo9 : Transformation of a Pauli Paramagnet into a Strong Permanent Magnet

    Science.gov (United States)

    Lamichhane, Tej N.; Taufour, Valentin; Palasyuk, Andriy; Lin, Qisheng; Bud'ko, Sergey L.; Canfield, Paul C.

    2018-02-01

    We report on the synthesis of single-crystal and polycrystalline samples of Ce3 -xMgxCo9 solid solution (0 ≤x ≲1.4 ) and characterization of their structural and magnetic properties. The crystal structure remains rhombohedral in the whole composition range and Mg partially replaces Ce in the 6 c site of the CeCo3 structure. Ferromagnetism is induced by Mg substitutions starting as low as x =0.18 and reaching a Curie temperature as high as 450 K for x =1.35 . Measurements on single crystals with x =1.34 and TC=440 K indicate an axial magnetic anisotropy with an anisotropy field of 6 T and a magnetization of 6 μB/f .u . at 300 K. Coercicity is observed in the polycrystalline samples consistent with the observed axial magnetic anisotropy. Our discovery of ferromagnetism with large axial magnetic anisotropy induced by substituting a rare-earth element by Mg is a very promising result in the search of inexpensive permanent-magnet materials and suggests that other nonmagnetic phases, similar to CeCo3 , may also conceal nearby ferromagnetic phases.

  15. Magnetic and resonant X-ray scattering investigations of strongly correlated electron systems; Etude de systemes electroniques fortement correles par diffusion magnetique et resonnante des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Paolasini, L.; Bergevin, F. de [European Synchrotron Radiation Facility, 38 - Grenoble (France)

    2008-06-15

    Resonant X-ray scattering is a method which combines high-Q resolution X-ray elastic diffraction and atomic core-hole spectroscopy for investigating electronic and magnetic long-range ordered structures in condensed matter. During recent years the development of theoretical models to describe resonant X-ray scattering amplitudes and the evolution of experimental techniques, which include the control and analysis of linear photon polarization and the introduction of extreme environment conditions such as low temperatures, high magnetic field and high pressures, have opened a new field of investigation in the domain of strongly correlated electron systems. (authors)

  16. Propagation of three-dimensional ion-acoustic solitary waves in magnetized negative ion plasmas with nonthermal electrons

    Science.gov (United States)

    El-Labany, S. K.; Sabry, R.; El-Taibany, W. F.; Elghmaz, E. A.

    2010-04-01

    Properties of small amplitude nonlinear ion-acoustic solitary waves in a warm magneto plasma with positive-negative ions and nonthermal electrons are investigated. For this purpose, the hydrodynamic equations for the positive-negative ions, nonthermal electron density distribution, and the Poisson equation are used to derive the corresponding nonlinear evolution equation; Zkharov-Kuznetsov (ZK) equation, in the small amplitude regime. The ZK equation is analyzed to examine the existence regions of the solitary pulses. It is found that compressive and rarefactive ion-acoustic solitary waves strongly depend on the mass and density ratios of the positive and negative ions as well as the nonthermal electron parameter. Also, it is found that there are two critical values for the density ratio of the negative-to-positive ions (υ), the ratio between unperturbed electron-to-positive ion density (μ), and the nonthermal electron parameter (β), which decide the existence of positive and negative ion-acoustic solitary waves. The present study is applied to examine the small amplitude nonlinear ion-acoustic solitary excitations for the (H+, O2-) and (H+, H-) plasmas, where they are found in the D- and F-regions of the Earth's ionosphere. This investigation should be helpful in understanding the salient features of the nonlinear ion-acoustic solitary waves in space and in laboratory plasmas where two distinct groups of ions and non-Boltzmann distributed electrons are present.

  17. Moderate and strong static magnetic fields directly affect EGFR kinase domain orientation to inhibit cancer cell proliferation

    Science.gov (United States)

    Wang, Wenchao; Li, Zhiyuan; Liu, Juanjuan; Yang, Xingxing; Ji, Xinmiao; Luo, Yan; Hu, Chen; Hou, Yubin; He, Qianqian; Fang, Jun; Wang, Junfeng; Liu, Qingsong; Li, Guohui; Lu, Qingyou; Zhang, Xin

    2016-01-01

    Static magnetic fields (SMFs) can affect cell proliferation in a cell-type and intensity-dependent way but the mechanism remains unclear. At the same time, although the diamagnetic anisotropy of proteins has been proposed decades ago, the behavior of isolated proteins in magnetic fields has not been directly observed. Here we show that SMFs can affect isolated proteins at the single molecular level in an intensity-dependent manner. We found that Epidermal Growth Factor Receptor (EGFR), a protein that is overexpressed and highly activated in multiple cancers, can be directly inhibited by SMFs. Using Liquid-phase Scanning Tunneling Microscopy (STM) to examine pure EGFR kinase domain proteins at the single molecule level in solution, we observed orientation changes of these proteins in response to SMFs. This may interrupt inter-molecular interactions between EGFR monomers, which are critical for their activation. In molecular dynamics (MD) simulations, 1-9T SMFs caused increased probability of EGFR in parallel with the magnetic field direction in an intensity-dependent manner. A superconducting ultrastrong 9T magnet reduced proliferation of CHO-EGFR cells (Chinese Hamster Ovary cells with EGFR overexpression) and EGFR-expressing cancer cell lines by ~35%, but minimally affected CHO cells. We predict that similar effects of magnetic fields can also be applied to some other proteins such as ion channels. Our paper will help clarify some dilemmas in this field and encourage further investigations in order to achieve a better understanding of the biological effects of SMFs. PMID:27223425

  18. Analytical study of a quasi-zero stiffness coupling using a torsion magnetic spring with negative stiffness

    Science.gov (United States)

    Zheng, Yisheng; Zhang, Xinong; Luo, Yajun; Zhang, Yahong; Xie, Shilin

    2018-02-01

    By now, many translation quasi-zero stiffness (QZS) mechanisms have been proposed to overcome the restriction between the isolation frequency range and the load bearing capacity of linear isolators. The couplings of rotor systems undertake the functions of transmitting static driving torque and isolating disturbing torque simultaneously, which creates the demand of torsion QZS mechanisms. Hence a QZS coupling is presented in this paper, where a torsion magnetic spring (TMS) composed of two coaxial ring magnet arrangements in repulsive configuration is employed to produce negative torsion stiffness to counteract the positive stiffness of a rubber spring. In this paper, the expressions of magnetic torque and stiffness are given firstly and verified by finite element simulations; and the effect of geometric parameters of the TMS on its stiffness characteristic is analyzed in detail, which contributes to the optimal design of the TMS. Then dynamic analysis of the QZS coupling is performed and the analytical expression of the torque transmissibility is achieved based on the Harmonic Balance Method. Finally, simulation of the torque transmissibility is carried out to reveal how geometric parameters of the TMS affect the isolation performance.

  19. Synthesis and characterization of a magnetic adsorbent from negatively-valued iron mud for methylene blue adsorption

    Science.gov (United States)

    Liu, Jiancong; Yu, Yang; Yang, Jiakuan; Song, Jian; Fan, Wei; Yu, Hongbin; Bian, Dejun; Huo, Mingxin

    2018-01-01

    With increasing awareness of reduction of energy and CO2 footprint, more waste is considered recyclable for generating value-added products. Here we reported the negatively-valued iron mud, a waste from groundwater treatment plant, was successfully converted into magnetic adsorbent. Comparing with the conventional calcination method under the high temperature and pressure, the synthesis of the magnetic particles (MPs) by Fe2+/Fe3+ coprecipitation was conducted at environment-friendly condition using ascorbic acid (H2A) as reduction reagent and nitric acid (or acid wastewater) as leaching solution. The MPs with major component of Fe3O4 were synthesized at the molar ratio (called ratio subsequently) of H2A to Fe3+ of iron mud ≥ 0.1; while amorphous ferrihydrite phase was formed at the ratio ≤ 0.05, which were confirmed by vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). With the ratio increased, the crystalline size and the crystallization degree of MPs increased, and thus the Brunauer-Emmett-Teller (BET) surface and the cation-exchange capacity (CEC) decreased. MPs-3 prepared with H2A to Fe3+ ratio of 0.1 demonstrated the highest methylene blue (MB) adsorption of 87.3 mg/g and good magnetic response. The adsorption of MB onto MPs agreed well with the non-linear Langmuir isotherm model and the pseudo-second-order model. Pilot-scale experiment showed that 99% of MB was removed by adding 10 g/L of MPs-3. After five adsorption-desorption cycles, MPs-3 still showed 62% removal efficiency for MB adsorption. When nitric acid was replaced by acid wastewater from a propylene plant, the synthesized MPs-3w showed 3.7 emu/g of saturation magnetization (Ms) and 56.7 mg/g of MB adsorption capacity, 2.8 times of the widely used commercial adsorbent of granular active carbon (GAC). The major mechanism of MPs adsorption for MB was electrostatic attraction and cation exchange. This study synthesized a magnetic adsorbent from

  20. Negative magnetic resonance imaging in femoral neck stress fracture with joint effusion: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Nobutoshi; Okuyama, Koichiro; Kamo, Keiji; Chiba, Mitsuho [Akita Rosai Hospital, Department of Orthopedic Surgery, Odate, Akita (Japan); Shimada, Yoichi [Akita University School of Medicine, Department of Orthopedic Surgery, Akita (Japan)

    2016-06-15

    Femoral neck stress fracture (FNSF) is well documented in the orthopedic literature and is generally associated with strenuous activities such as long-distance running and military training. The diagnostic yield of magnetic resonance imaging (MRI) for FNSF was reported to be 100 %, and early MRI is recommended when this fracture is suspected. We encountered a 16-year-old male long-distance runner with FNSF in whom the left femoral neck showed no signal changes on MRI although an effusion was detected in the left hip joint. One month later, roentgenograms revealed periosteal callus and oblique consolidation of the left femoral neck, confirming the diagnosis of compression FNSF. Because FNSF with a normal bone marrow signal on MRI is very rare, this patient is presented here. (orig.)

  1. Risk Factors of False-Negative Magnetic Resonance Imaging Diagnosis for Meniscal Tear Associated With Anterior Cruciate Ligament Tear.

    Science.gov (United States)

    Ahn, Ji Hyun; Jeong, Seung Hyo; Kang, Ho Won

    2016-06-01

    To identify risk factors that predict false-negative magnetic resonance imaging (MRI) diagnosis for meniscal tear coincident with anterior cruciate ligament injury using multivariate logistic regression. We reviewed the medical records of consecutive patients who underwent arthroscopic anterior cruciate ligament reconstruction from January 2006 through December 2014. Exclusion criteria were no meniscal tear or incomplete tear less than 10 mm in length, delay to surgery from initial injury more than 1 year, delay to surgery from preoperative MRI more than 4 weeks, revisions, fracture histories, and multiple ligament injuries. According to preoperative MRI diagnosis, the meniscal tears were sorted into true-positive MRI and false-negative MRI groups. Multivariate logistic regression was used to analyze risk factors including age, gender, body mass index, time from injury to MRI, knee instability, concomitant ligament injury, intra-articular effusion, bone contusion, cartilage injury, meniscal tear location, and meniscal tear pattern. Enrolled 249 meniscal tears (159 medial and 90 lateral menisci) were sorted into true-positive MRI (n = 136) and false-negative MRI (n = 113) groups. As time from injury to MRI diagnosis increased, the risk of the false-negative MRI diagnosis decreased (adjusted odds ratio [OR], 0.859; 95% confidence interval [CI], 0.802-0.921). Meniscal tear location within the posterior one-third was a significant risk factor compared with tear within the anterior one-third (adjusted OR, 11.823; 95% CI, 2.272-61.519). Peripheral longitudinal tear pattern was also a significant risk factor (adjusted OR, 3.522; 95% CI, 1.256-9.878). Significant risk factors for false-negative MRI included short time from injury to MRI diagnosis, meniscal tear location within the posterior one-third, and peripheral longitudinal tear pattern. Level III, retrospective comparative study. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier

  2. Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

    Science.gov (United States)

    Vikas, Hash(0x125f4490)

    2011-02-01

    Evolution of the helium atom in a strong time-dependent (TD) magnetic field ( B) of strength up to 1011 G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schrödinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >109 G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >109 G, the conventional TD-DFT based approach differs "dynamically" from the CDFT based approach under similar computational constraints.

  3. Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

    International Nuclear Information System (INIS)

    Vikas

    2011-01-01

    Evolution of the helium atom in a strong time-dependent (TD) magnetic field (B) of strength up to 10 11 G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schroedinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >10 9 G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >10 9 G, the conventional TD-DFT based approach differs 'dynamically' from the CDFT based approach under similar computational constraints. (author)

  4. Electron gas interacting in a metal, submitted to a strong magnetic field; Gas de eletrons interagentes num metal, sujeito a um campo magnetico forte

    Energy Technology Data Exchange (ETDEWEB)

    Alcaraz, Francisco Castilho

    1977-07-01

    Using the propagator's technique in the grand ensemble developed by Montroll and Ward we investigate the magnetic properties of an interacting electron gas in a strong magnetic field. The free propagator properly constructed shows that the spin paramagnetism does not have a term with strong temperature dependence, contrary to the result of Isihara. Considering the electron density to be constant, the dHVA oscillations in the magnetic susceptibility and sound velocity, considering the effects of first exchange interactions, show only one phase in agreement with experimental result, while Ichimura and Isihara obtained two phases differing by {pi}/2. The effects of first order exchange interactions in the dHVA oscillations of the magnetic susceptibility and sound velocity give rise to an exponential factor in the amplitudes of oscillator (Dingle factor), being the Dingle temperature linearly dependent of the Fermi velocity. The calculations of the ring diagram contribution to the grand partition function, show that the approximation used by Isihara for this calculations is not good and the dHVA oscillations of the contributions from the ring diagrams for the grand partition function have a phase differing by {pi}/2 from that obtained by Isihara. (author)

  5. Unusual deep vein thrombosis sites: magnetic resonance venography in patients with negative compression ultrasound and symptomatic pulmonary embolism.

    Science.gov (United States)

    Gary, T; Steidl, K; Belaj, K; Hafner, F; Froehlich, H; Deutschmann, H; Pilger, E; Brodmann, M

    2014-02-01

    To evaluate the clinical characteristics of patients with pulmonary embolism (PE), negative compression ultrasound (CUS) of the lower limbs and detection of unusual deep vein thrombosis (DVT) sites by means of magnetic resonance (MR) venography. A retrospective data analysis of PE patients hospitalized at our institution from April 2009 to 2011. From April 2009 to 2011, a total of 762 PE patients were treated at our institution. In 169 of these patients CUS for DVT was negative. In these patients MR venography was performed for further evaluation. We found venous thrombosis at unusual sites in 12 of these patients. Due to free floating thrombus masses and fear of life-threatening PE progression we inserted an inferior vena cava filter in three of these 12 patients. The leading venous thromboembolism risk factor in our patients was immobilization (5 patients, 41.7%). We conclude that especially in patients with PE and negative CUS of the lower limbs a thrombosis of the pelvic veins should be considered in case of symptoms for venous thrombosis in this area. Further diagnostic work-up with MR venography should be scheduled in these patients especially in patients with risk factor immobilization as therapeutic consequences might occur.

  6. Effect of a strong, DC-induced magnetic field on circadian singing activity of the house cricket (orthoptera:gryllidae)

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, K.C.; Bitzer, R.J.; Galliart, L. [Iowa State Univ., Ames, IA (United States)] [and others

    1995-05-01

    We investigated the effect of a strong, DC-induced electromagnetic field (EMF) on the circadian singing activity of the house cricket, Acheta domesticus (L.). Groups of 10 crickets were exposed to strong, DC-induced EMFs under two light regimes, 12:12 (L:D) h and 0:24 (L:D) h. Exposure to the strong EMF resulted in an increase in mean time per hour during which one or more crickets were singing and in number of crickets singing per hour. Correcting for phase shift during O:24 (L:D) h, the daily pattern of singing was apparently unaffected by any treatment. The greatest percentage of singing and number of crickets singing per hour occurred during actual or expected scotophase. This is the first report of an increase in insect activity during exposure to a strong DC-induced EMF.

  7. Negative magnetic resonance imaging in three cases of anterior tibial cortex stress fractures

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Ralph; Moghal, M.; Newton, J.L.; Jones, N. [Oxford University Hospitals NHS Foundation Trust, Department of Sport and Exercise Medicine, Nuffield Orthopaedic Centre, Oxford (United Kingdom); Teh, J. [Oxford University Hospitals NHS Foundation Trust, Department of Radiology, Nuffield Orthopaedic Centre Oxford, Oxford (United Kingdom)

    2017-12-15

    Anterior mid-tibial cortex stress fractures (ATCSF) are uncommon and notoriously challenging to treat. They are termed high risk due to their predilection to prolonged recovery, nonunion and complete fracture. Early diagnosis is essential to avoid progression and reduce fracture complications. Imaging plays a key role in confirming the diagnosis. Magnetic resonance imaging (MRI) is accepted as the gold standard modality due to its high accuracy and nonionizing properties. This report describes three cases of ATCSFs in recreational athletes who had positive radiographic findings with no significant MRI changes. Two athletes had multiple striations within their tibias. Despite the radiographic findings, their severity of symptoms were low with mild or no tenderness on examination. Clinicians should be mindful that the ATCSFs may not present with typical acute stress fracture symptoms. We recommend that plain radiographs should be used as the first line investigation when suspecting ATCSFs. Clinicians should be aware that despite MRI being considered the gold standard imaging modality, we report three cases where the MRI was unremarkable, whilst radiographs and computed tomography confirmed the diagnosis. We urge clinicians to continue to use radiographs as the first line imaging modality for ATCSFs and not to directly rely on MRI. Those who opt directly for MRI may be falsely reassured causing a delay in diagnosis. (orig.)

  8. Negative magnetic resonance imaging in three cases of anterior tibial cortex stress fractures

    International Nuclear Information System (INIS)

    Smith, Ralph; Moghal, M.; Newton, J.L.; Jones, N.; Teh, J.

    2017-01-01

    Anterior mid-tibial cortex stress fractures (ATCSF) are uncommon and notoriously challenging to treat. They are termed high risk due to their predilection to prolonged recovery, nonunion and complete fracture. Early diagnosis is essential to avoid progression and reduce fracture complications. Imaging plays a key role in confirming the diagnosis. Magnetic resonance imaging (MRI) is accepted as the gold standard modality due to its high accuracy and nonionizing properties. This report describes three cases of ATCSFs in recreational athletes who had positive radiographic findings with no significant MRI changes. Two athletes had multiple striations within their tibias. Despite the radiographic findings, their severity of symptoms were low with mild or no tenderness on examination. Clinicians should be mindful that the ATCSFs may not present with typical acute stress fracture symptoms. We recommend that plain radiographs should be used as the first line investigation when suspecting ATCSFs. Clinicians should be aware that despite MRI being considered the gold standard imaging modality, we report three cases where the MRI was unremarkable, whilst radiographs and computed tomography confirmed the diagnosis. We urge clinicians to continue to use radiographs as the first line imaging modality for ATCSFs and not to directly rely on MRI. Those who opt directly for MRI may be falsely reassured causing a delay in diagnosis. (orig.)

  9. Separation of species of a binary fluid mixture confined in a channel in presence of a strong transverse magnetic field

    Directory of Open Access Journals (Sweden)

    Sharma Bishwaram

    2012-01-01

    Full Text Available Effects of a transverse magnetic field on separation of a binary mixture of incompressible viscous thermally and electrically conducting fluids confined between two stationary parallel plates are examined. Both the plates are maintained at constant temperatures. It is assumed that one of the components, which is rarer and lighter, is present in the mixture in a very small quantity. The equations governing the motion, temperature and concentration in Cartesian coordinate are solved analytically. The solution obtained for concentration distribution is plotted against the width of the channel for various values of non-dimensional parameters. It is found that the effect of transverse magnetic field is to separate the species of rarer and lighter component by contributing its effect directly to the temperature gradient and the pressure gradient. The effects of increase in the values of Hartmann number, magnetic Reynolds number, barodiffusion number, thermal diffusion number, electric field parameter and the product of Prandtl number and Eckert number are to collect the rarer and lighter component near the upper plate and throw away the heavier component towards the lower plate. The problem discussed here derives its application in the basic fluid dynamics separation processes to separate the rare component of the different isotopes of heavier molecules where electromagnetic method of separation does not work.

  10. The negative predictive value of breast Magnetic Resonance Imaging in noncalcified BIRADS 3 lesions.

    Science.gov (United States)

    Dorrius, M D; Pijnappel, R M; Sijens, P E; van der Weide, M C Jansen; Oudkerk, M

    2012-02-01

    The purpose of this study is to determine whether breast MRI can provide a sufficient NPV to safely rule out malignancy in mammographic BIRADS 3 lesions. In a 3-year consecutive mammographic examination study 176 out of 4391 patients had a lesion classified as BIRADS 3. 76 out of 176 patients underwent breast MRI as diagnostic work-up. Lesions which MRI classified as BIRADS 1 or 2 were considered negative for malignancy. Sensitivity, specificity, PPV and NPV were calculated. In 27 out of 76 (35.5%) patients MRI showed no enhancement and was classified as BIRADS 1. In 25 (32.9%) patients MRI showed focal or mass enhancement classified as BIRADS 2. In these 52 (68.4%) patients no malignancy was found during at least 2 years study follow-up. The other 24 (31.6%) patients had a lesion classified as BIRADS ≥ 3. Thirteen of these 24 lesions were malignant by pathology. MRI had a sensitivity of 100% (95% CI: 75-100%), specificity of 82.5% (95% CI: 71-91%), PPV of 54.2% (95% CI: 33-74%) and NPV of 100% (95% CI: 93-100%). Breast MRI should be used in a diagnostic strategy for the work-up of noncalcified BIRADS 3 lesions. Malignancy is ruled out with a very high level of confidence in the majority of patients (68%), herewith avoiding invasive diagnostic procedures. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  11. Ionospheric convection response to changes of interplanetary magnetic field B-z component during strong B-y component

    DEFF Research Database (Denmark)

    Huang, C.S.; Murr, D.; Sofko, G.J.

    2000-01-01

    enough, the B-z reorientation causes changes in the flow intensity but not in the shape of the convection pattern. The results show the characteristics of ionospheric convection response during strong B-y and suggest that the convection reconfiguration is not only determined by the changing B-z but also...... the dawn-dusk meridian plane, which is interpreted as propagation or expansion of newly generated convection cells in the cusp region. Other studies showed that the change in convection pattern in response to IMF reorientations is spatially fixed. In this paper, we investigate the ionospheric convection...... response to IMF Bz changes during strong IMF BZ. On March 23, 1995, B-x was small, B-y was strongly positive (7-11 nT), and the B-z polarity changed several times after 1300 UT. The dayside ionospheric convection is dominated by a large clockwise convection cell. The cell focus (the "eye" of the convection...

  12. Breast magnetic resonance imaging significance for breast cancer diagnostic in women with genetic predisposition and a strong family history

    Directory of Open Access Journals (Sweden)

    M. S. Karpova

    2013-01-01

    Full Text Available Screening of breast cancer with mammography recommended to women over 40 has been shown to decrease breast cancer mortality. But mam- mography has much lower accuracy in young women with BRCA1/2 mutations and women with a strong family history. Therefore new screening methods in young high-risk women are necessary to detect early-stage cancer.

  13. The magnetic properties of $^{\\rm 177}$Hf and $^{\\rm 180}$Hf in the strong coupling deformed model

    OpenAIRE

    Muto, S.; Stone, N. J.; Bingham, C. R.; Stone, J. R.; Walker, P. M.; Audi, G.; Gaulard, C.; Köster, U.; Nikolov, J.; Nishimura, K.; Ohtsubo, T.; Podolyak, Z.; Risegari, L.; Simpson, G. S.; Veskovic, M.

    2014-01-01

    This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2$^-$, 51.4 m, 2740 keV state in $^{\\rm 177}$Hf and the 8$^-$, 5.5 h, 1142 keV state in $^{\\rm 180}$Hf by the method of on-line nuclear orientation. Also included are results on the angular distributions of gamma transitions in the decay of the $^{\\rm 177}$Hf isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2$^+$, 1.1 s, isomer at 1315 keV ...

  14. B fields in OB stars (BOB): Detection of a magnetic field in the He-strong star CPD -57° 3509

    Science.gov (United States)

    Przybilla, N.; Fossati, L.; Hubrig, S.; Nieva, M.-F.; Järvinen, S. P.; Castro, N.; Schöller, M.; Ilyin, I.; Butler, K.; Schneider, F. R. N.; Oskinova, L. M.; Morel, T.; Langer, N.; de Koter, A.; BOB Collaboration

    2016-03-01

    Aims: We report the detection of a magnetic field in the helium-strong star CPD -57° 3509 (B2 IV), a member of the Galactic open cluster NGC 3293, and characterise the star's atmospheric and fundamental parameters. Methods: Spectropolarimetric observations with FORS2 and HARPSpol are analysed using two independent approaches to quantify the magnetic field strength. A high-S/N FLAMES/GIRAFFE spectrum is analysed using a hybrid non-LTE model atmosphere technique. Comparison with stellar evolution models constrains the fundamental parameters of the star. Results: We obtain a firm detection of a surface averaged longitudinal magnetic field with a maximum amplitude of about 1 kG. Assuming a dipolar configuration of the magnetic field, this implies a dipolar field strength larger than 3.3 kG. Moreover, the large amplitude and fast variation (within about 1 day) of the longitudinal magnetic field implies that CPD -57° 3509 is spinning very fast despite its apparently slow projected rotational velocity. The star should be able to support a centrifugal magnetosphere, yet the spectrum shows no sign of magnetically confined material; in particular, emission in Hα is not observed. Apparently, the wind is either not strong enough for enough material to accumulate in the magnetosphere to become observable or, alternatively, some leakage process leads to loss of material from the magnetosphere. The quantitative spectroscopic analysis of the star yields an effective temperature and a logarithmic surface gravity of 23 750 ± 250 K and 4.05 ± 0.10, respectively, and a surface helium fraction of 0.28 ± 0.02 by number. The surface abundances of C, N, O, Ne, S, and Ar are compatible with the cosmic abundance standard, whereas Mg, Al, Si, and Fe are depleted by about a factor of 2. This abundance pattern can be understood as the consequence of a fractionated stellar wind. CPD -57° 3509 is one of the most evolved He-strong stars known with an independent age constraint due to its

  15. An ionization pressure gauge with LaB6 emitter for long-term operation in strong magnetic fields

    Science.gov (United States)

    Wenzel, U.; Pedersen, T. S.; Marquardt, M.; Singer, M.

    2018-03-01

    We report here on a potentially significant improvement in the design of neutral pressure gauges of the so-called ASDEX-type which were first used in the Axially Symmetric Divertor EXperiment (ASDEX). Such gauges are considered state-of-the-art and are in wide use in fusion experiments, but they nonetheless suffer from a relatively high failure rate when operated at high magnetic field strengths for long times. This is therefore a significant concern for long-pulse, high-field experiments such as Wendelstein 7-X (W7-X) and ITER. The new design is much more robust. The improvement is to use a LaB6 crystal instead of a tungsten wire as the thermionic emitter of electrons in the gauge. Such a LaB6 prototype gauge was successfully operated for a total of 60 h in B = 3.1 T, confirming the significantly improved robustness of the new design and qualifying it for near-term operation in W7-X. With the LaB6 crystal, an order of magnitude reduction in heating current is achieved, relative to the tungsten filament based gauges, from 15-20 A to 1-2 A. This reduces the Lorenz forces and the heating power by an order of magnitude also and is presumably the reason for the much improved robustness. The new gauge design, test environment setup at the superconducting magnet, and results from test operation are described.

  16. Negative Differential Velocity in Artificial Crystals Probed by High Magnetic Fields

    Science.gov (United States)

    Patanè, A.

    -level, where they become spatially localized.7-10 This Resonant Electron Localization in Electric Field, to which we give the acronym RELIEF, leads to NDV and strongly non-linear current-voltage characteristics. We envisage that the RELIEF-effect could be observed in other III-N-V alloys, such as InP1-xNx and InAs1-xNx. In these compounds the nature of the resonant interaction between the N-level and the conduction band states of the host-crystal is still relatively unexplored. However, it is clear that the different energy positions of the N-level relative to the conduction band minimum of different materials could offer new degrees of freedom in the design of the electronic band structure and electron dynamics. The RELIEF-effect may open up prospects for future applications in fast electronics. We have shown that the maximum response frequency, fmax, of a RELIEF-diode can be tuned by the applied electric field in the THz frequency range.7 This is of potential technological significance for the development of detectors/sources in the 0.6-1 THz region, which is not currently attainable using conventional Transferred Electron Devices and Quantum Cascade Lasers. Our recent studies of GaAs1-xNx have also shown a fast response of the current in the sub-T

  17. Strong static magnetic fields of NMR: Do they affect tissue perfusion. Beeinflussen starke statische Magnetfelder in der NMR-Tomographie die Gewebedurchblutung

    Energy Technology Data Exchange (ETDEWEB)

    Stick, C.; Hinkelmann, K. (Kiel Univ. (Germany, F.R.). Inst. fuer Angewandte Physiologie und Medizinische Klimatologie); Eggert, P. (Kiel Univ. (Germany, F.R.). Abt. Allgemeine Paediatrie); Wendhausen, H. (Kiel Univ. (Germany, F.R.). Abt. Radiologie)

    1991-03-01

    Findings obtained in humans and test animals raised the question whether strong static magnetic fields as used in NMR-tomography may affect tissue perfusion. In two test series including 20 subjects, each skin blood flow at the thumb was determined by heat clearance, and forearm blood flow was measured by venous occlusion plethysmography. For comparative purposes, measurements were carried out bilaterally at both extremities. The experiments consisted of three sections that lasted 10 min each. During the second section the thumb or the forearm were unilaterally exposed to magnetic fields of 0,9 to 1 T and 0.4 to 0.5 T, respectively. The results of this section were compared with the values obtained during the experimental sections prior to and after the exposure to the magnetic field. The results were also compared with the blood flow measured at the contralateral extremity. Neither at the skin of the thumb nor at the forearm were there changes in local blood flow attributable to the magnetic fields applied. (orig.).

  18. Thickness Dependence of Magnetic Relaxation and E-J Characteristics in Superconducting (Gd-Y)-Ba-Cu-O Films with Strong Vortex Pinning

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Ozgur [ORNL; Sinclair IV, John W [ORNL; Zuev, Yuri L [ORNL; Thompson, James R [ORNL; Christen, David K [ORNL; Cook, Sylvester W [ORNL; Kumar, Dhananjay [ORNL; Chen, Y [SuperPower Incorporated, Schenectady, New York; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York

    2011-01-01

    The dependence of the critical current density Jc on temperature, magnetic field, and film thickness has been investigated in (Gd-Y)BaCu-oxide materials of 0.7, 1.4, and 2.8 m thickness. Generally, the Jc decreases with film thickness at investigated temperatures and magnetic fields. The nature and strength of the pinning centers for vortices have been identified through angular and temperature measurements, respectively. These films do not exhibit c-axis correlated vortex pinning, but do have correlated defects oriented near the ab-planes. For all film thicknesses studied, strong pinning dominates at most temperatures. The vortex dynamics were investigated through magnetic relaxation studies in the temperature range of 5 77 K in 1 T and 3 T applied magnetic fields, H || surface-normal. The creep rate S is thickness dependent at high temperatures, implying that the pinning energy is also thickness dependent. Maley analyses of the relaxation data show an inverse power law variation for the effective pinning energy Ueff ~ (J0/J) . Finally, the electric field-current density (E-J) characteristics were determined over a wide range of dissipation by combining experimental results from transport, swept field magnetometry (VSM), and Superconducting Quantum Interference Device (SQUID) magnetometry. We develop a self-consistent model of the combined experimental results, leading to an estimation of the critical current density Jc0(T) in the absence of flux creep.

  19. Current induced multi-mode propagating spin waves in a spin transfer torque nano-contact with strong perpendicular magnetic anisotropy

    Science.gov (United States)

    Mohseni, S. Morteza; Yazdi, H. F.; Hamdi, M.; Brächer, T.; Mohseni, S. Majid

    2018-03-01

    Current induced spin wave excitations in spin transfer torque nano-contacts are known as a promising way to generate exchange-dominated spin waves at the nano-scale. It has been shown that when these systems are magnetized in the film plane, broken spatial symmetry of the field around the nano-contact induced by the Oersted field opens the possibility for spin wave mode co-existence including a non-linear self-localized spin-wave bullet and a propagating mode. By means of micromagnetic simulations, here we show that in systems with strong perpendicular magnetic anisotropy (PMA) in the free layer, two propagating spin wave modes with different frequency and spatial distribution can be excited simultaneously. Our results indicate that in-plane magnetized spin transfer nano-contacts in PMA materials do not host a solitonic self-localized spin-wave bullet, which is different from previous studies for systems with in plane magnetic anisotropy. This feature renders them interesting for nano-scale magnonic waveguides and crystals since magnon transport can be configured by tuning the applied current.

  20. Investigations of ultrafast ligand rebinding to heme and heme proteins using temperature and strong magnetic field perturbations

    Science.gov (United States)

    Zhang, Zhenyu

    This thesis is written to summarize investigations of the mechanisms that underlie the kinetics of diatomic ligand rebinding to the iron atom of the heme group, which is chelated inside heme proteins. The family of heme proteins is a major object of studies for several branches of scientific research activity. Understanding the ligand binding mechanisms and pathways is one of the major goals for biophysics. My interests mainly focus on the physics of this ligand binding process. Therefore, to investigate the problem, isolated from the influence of the protein matrix, Fe-protophorphyrin IX is chosen as the prototype system in my studies. Myoglobin, the most extensively and intensively studied protein, is another ideal system that allows coupling the protein polypeptide matrix into the investigation. A technique to synchro-lock two laser pulse trains electronically is applied to our pump-probe spectroscopic studies. Based on this technique, a two color, fs/ps pump-probe system is developed which extends the temporal window for our investigation to 13ns and fills a gap existing in previous pump-probe investigations. In order to apply this newly-developed pump-probe laser system to implement systematic studies on the kinetics of diatomic ligand (NO, CO, O2) rebinding to heme and heme proteins, several experimental setups are utilized. In Chapter 1, the essential background knowledge, which helps to understand the iron-ligand interaction, is briefly described. In Chapter 2, in addition to a description of the preparation protocols of protein samples and details of the method for data analysis, three home-made setups are described, which include: a picosecond laser regenerative amplifier, a pump-probe application along the bore (2-inch in diameter) of a superconducting magnet and a temperature-controllable cryostat for spinning sample cell. Chapter 3 presents high magnetic field studies of several heme-ligand or protein-ligand systems. Pump-probe spectroscopy is used to

  1. Extreme enhancement of blocking temperature by strong magnetic dipoles interaction of α-Fe nanoparticle-based high-density agglomerate

    International Nuclear Information System (INIS)

    Kura, H; Takahashi, M; Ogawa, T

    2011-01-01

    High-volume fraction α-Fe nanoparticle (NP) agglomerates were prepared using chemically synthesized NPs. In the agglomerate, NPs are separated by surfactant and NP superlattice with a hexagonal close-packed structure is locally realized. Volume fractions of NPs at 20% and 42% were obtained in agglomerates consisting of 2.9 nm and 8.2 nm diameter NPs, respectively. The high saturation magnetization of α-Fe NPs and high volume fraction of NPs in the agglomerate provide strong magnetic dipole-dipole interaction. The interaction energy of the agglomerate became much larger than the anisotropic energy of individual NPs. As a result, the blocking temperature of the 8.2 nm NP agglomerate was significantly enhanced from 52.2 K to around 500 K. (fast track communication)

  2. Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Vikas [Quantum Chemistry Group, Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, 160014 Chandigrah (India)

    2011-02-15

    Evolution of the helium atom in a strong time-dependent (TD) magnetic field (B) of strength up to 10{sup 11} G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schroedinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >10{sup 9} G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >10{sup 9} G, the conventional TD-DFT based approach differs 'dynamically' from the CDFT based approach under similar computational constraints. (author)

  3. Daytime geomagnetic disturbances at high latitudes during a strong magnetic storm of June 21-23, 2015: The storm initial phase

    Science.gov (United States)

    Gromova, L. I.; Kleimenova, N. G.; Levitin, A. E.; Gromov, S. V.; Dremukhina, L. A.; Zelinskii, N. R.

    2016-05-01

    The high-latitude geomagnetic effects of an unusually long initial phase of the largest magnetic storm ( SymH ~-220 nT) in cycle 24 of the solar activity are considered. Three interplanetary shocks characterized by considerable solar wind density jumps (up to 50-60 cm-3) at a low solar wind velocity (350-400 km/s) approached the Earth's magnetosphere during the storm initial phase. The first two dynamic impacts did not result in the development of a magnetic storm, since the IMF Bz remained positive for a long time after these shocks, but they caused daytime polar substorms (magnetic bays) near the boundary between the closed and open magnetosphere. The magnetic field vector diagrams at high latitudes and the behaviour of high-latitude long-period geomagnetic pulsations ( ipcl and vlp) made it possible to specify the dynamics of this boundary position. The spatiotemporal features of daytime polar substorms (the dayside polar electrojet, PE) caused by sudden changes in the solar wind dynamic pressure are discussed in detail, and the singularities of ionospheric convection in the polar cap are considered. It has been shown that the main phase of this two-stage storm started rapidly developing only when the third most intense shock approached the Earth against a background of large negative IMF Bz values (to-39 nT). It was concluded that the dynamics of convective vortices and the related restructing of the field-aligned currents can result in spatiotemporal fluctuations in the closing ionospheric currents that are registered on the Earth's surface as bay-like magnetic disturbances.

  4. Extraction of negative pionlike particles from a H{sub 2} or D{sub 2} gas discharge plasma in magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Uramoto, Joshin

    1995-09-01

    Electron density in outside region of H{sub 2} or D{sub 2} gas discharge plasma along magnetic field, is abruptly reduced as H{sup -} or D{sup -} ions are produced. From the region, negative pionlike particles are extracted together with H{sup -} or D{sup -} ions. Then, a positive bias voltage is necessary for the beam collector of magnetic mass analyzer. (author).

  5. On the impact of the elastic-plastic flow upon the process of destruction of the solenoid in a super strong pulsed magnetic field

    Science.gov (United States)

    Krivosheev, S. I.; Magazinov, S. G.; Alekseev, D. I.

    2018-01-01

    At interaction of super strong magnetic fields with a solenoid material, a specific mode of the material flow forms. To describe this process, magnetohydrodynamic approximation is traditionally used. The formation of plastic shock-waves in material in a rapidly increasing pressure of 100 GPa/μs, can significantly alter the distribution of the physical parameters in the medium and affect the flow modes. In this paper, an analysis of supporting results of numerical simulations in comparison with available experimental data is presented.

  6. Pacemaker reed switch behavior in 0.5, 1.5, and 3.0 Tesla magnetic resonance imaging units: are reed switches always closed in strong magnetic fields?

    Science.gov (United States)

    Luechinger, Roger; Duru, Firat; Zeijlemaker, Volkert A; Scheidegger, Markus B; Boesiger, Peter; Candinas, Reto

    2002-10-01

    MRI is established as an important diagnostic tool in medicine. However, the presence of a cardiac pacemaker is usually regarded as a contraindication for MRI due to safety reasons. The aim of this study was to investigate the state of a pacemaker reed switch in different orientations and positions in the main magnetic field of 0.5-, 1.5-, and 3.0-T MRI scanners. Reed switches used in current pacemakers and ICDs were tested in 0.5-, 1.5-, and 3.0-T MRI scanners. The closure of isolated reed switches was evaluated for different orientations and positions relative to the main magnetic field. The field strengths to close and open the reed switch and the orientation dependency of the closed state inside the main magnetic field were investigated. The measurements were repeated using two intact pacemakers to evaluate the potential influence of the other magnetic components, like the battery. If the reed switches were oriented parallel to the magnetic fields, they closed at 1.0 +/- 0.2 mT and opened at 0.7 +/- 0.2 mT. Two different reed switch behaviors were observed at different magnetic field strengths. In low magnetic fields ( 200 mT), the reed switches opened in 50% of all tested orientations. No difference between the three scanners could be demonstrated. The reed switches showed the same behavior whether they were isolated or an integral part of the pacemakers. The reed switch in a pacemaker or an ICD does not necessarily remain closed in strong magnetic fields at 0.5, 1.5, or 3.0 T and the state of the reed switch may not be predictable with certainty in clinical situations.

  7. Ionospheric convection response to changes of interplanetary magnetic field B-z component during strong B-y component

    DEFF Research Database (Denmark)

    Huang, C.S.; Murr, D.; Sofko, G.J.

    2000-01-01

    the dawn-dusk meridian plane, which is interpreted as propagation or expansion of newly generated convection cells in the cusp region. Other studies showed that the change in convection pattern in response to IMF reorientations is spatially fixed. In this paper, we investigate the ionospheric convection...... response to IMF Bz changes during strong IMF BZ. On March 23, 1995, B-x was small, B-y was strongly positive (7-11 nT), and the B-z polarity changed several times after 1300 UT. The dayside ionospheric convection is dominated by a large clockwise convection cell. The cell focus (the "eye" of the convection...... pattern) is located in the prenoon sector for northward B-z and in the postnoon sector for southward B-z. It is found that the cell focus shifts from the prenoon sector to the postnoon sector following a southward BL turning and vice versa for a northward B-z turning. However, the motion of the convection...

  8. Polarized neutron reflectometry study on BiFeO3/Co0.9Fe0.1 heterostructures: enhanced magnetization in BiFeO3 and strong magnetic coupling at interface

    Science.gov (United States)

    Wang, Qiang; Gao, Ya; Ramesh, Ramamoorthy; Fitzsimmons, Michael

    2015-03-01

    Polarized neutron reflectometry (PNR) quantified the uncompensated magnetization occurring throughout the thickness of a BiFeO3 (BFO)/ Co0.9Fe0.1 (CoFe) heterostructures. The net uncompensated magnetization (1.0 μB/Fe) within BFO layer is much larger than that which has been theoretically predicted (0.1 μB/Fe) due to the Dzyaloshinskii-Moriya (DM) type interaction. The field dependent study indicates strong interfacial coupling between BFO and CoFe which extends into CoFe layer within about 1 nm interfacial region. The study also suggests the uncompensated magnetization in the BFO layer has relatively small anisotropy.

  9. Carboxyl and negative charge-functionalized superparamagnetic nanochains with amorphous carbon shell and magnetic core: synthesis and their application in removal of heavy metal ions.

    Science.gov (United States)

    Wang, Hui; Chen, Qian-Wang; Chen, Jian; Yu, Bin-Xing; Hu, Xian-Yi

    2011-11-01

    This communication describes carboxyl-functionalized nanochains with amorphous carbon shell (18 nm) and magnetic core using ferrocene as a single reactant under the induction of an external magnetic field (0.40 T), which shows a superparamagnetic behavior and magnetization saturation of 38.6 emu g(-1). Because of mesoporous structure (3.8 nm) and surface negative charge (-35.18 mV), the nanochains can be used as adsorbent for removing the heavy metal ions (90%) from aqueous solution.

  10. Scattering of the transverse magnetic modes from an abruptly ended strongly asymmetrical slab waveguide by an accelerated integral equation technique.

    Science.gov (United States)

    Manenkov, A B; Latsas, G P; Tigelis, L G

    2001-12-01

    We study the problem of the scattering of the first TM guided mode from an abruptly ended strongly asymmetrical slab waveguide by an improved iteration technique, which is based on the integral equation method with "accelerating" parameters. We demonstrate that the values of these parameters are related to the variational principle, and we save approximately 1-2 iterations compared with the case in which these parameters are not employed. The tangential electric-field distribution on the terminal plane, the reflection coefficient of the first TM guided mode, and the far-field radiation pattern are computed. Furthermore, a simple technique based on the Aitken extrapolation procedure is employed for faster computation of the higher-order solutions of the reflection coefficient. Numerical results are presented for several cases of abruptly ended waveguides, including systems with variational profile, while special attention is given to the far-field radiation pattern rotation and its explanation.

  11. The effective use of acai juice, blueberry juice and pineapple juice as negative contrast agents for magnetic resonance cholangiopancreatography in children

    International Nuclear Information System (INIS)

    Bittman, Mark E.; Callahan, Michael J.

    2014-01-01

    Magnetic resonance cholangiopancreatography (MRCP) is commonly performed in the evaluation of known or suspected pancreaticobiliary disease in children. The administration of a negative oral contrast agent can improve the quality of the examination without significant additional cost. We describe our experience with certain brands of acai juice, blueberry juice and pineapple juice as negative oral contrast agents in children. We believe these fruit juices are safe, palatable and may improve MRCP image quality. (orig.)

  12. The effective use of acai juice, blueberry juice and pineapple juice as negative contrast agents for magnetic resonance cholangiopancreatography in children

    Energy Technology Data Exchange (ETDEWEB)

    Bittman, Mark E. [Cohen Children' s Medical Center of New York, North Shore Long Island Jewish Health System, Department of Radiology, New Hyde Park, NY (United States); Callahan, Michael J. [Boston Children' s Hospital, Department of Radiology, Boston, MA (United States)

    2014-07-15

    Magnetic resonance cholangiopancreatography (MRCP) is commonly performed in the evaluation of known or suspected pancreaticobiliary disease in children. The administration of a negative oral contrast agent can improve the quality of the examination without significant additional cost. We describe our experience with certain brands of acai juice, blueberry juice and pineapple juice as negative oral contrast agents in children. We believe these fruit juices are safe, palatable and may improve MRCP image quality. (orig.)

  13. Radio emission from the X-ray pulsar Her X-1: a jet launched by a strong magnetic field neutron star?

    Science.gov (United States)

    van den Eijnden, J.; Degenaar, N.; Russell, T. D.; Miller-Jones, J. C. A.; Wijnands, R.; Miller, J. M.; King, A. L.; Rupen, M. P.

    2018-01-01

    Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like low-mass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disc. We measure a radio flux density of 38.7 ± 4.8 μJy at 9 GHz but cannot constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launching of jets by NSs with strong magnetic fields.

  14. Design features of a planar hybrid/permanent magnet strong-focusing undulator for Free Electron Laser (FEL) and Synchrotron Radiation (SR) applications

    Science.gov (United States)

    Tatchyn, Roman

    1997-05-01

    Insertion devices for Angstrom-wavelength Free Electron Laser (FEL) amplifiers driven by multi-GeV electron beams generally require distributed focusing substantially stronger than their natural focusing fields(C. Pellegrini, "A 4 to 0.1 nm FEL Based on the SLAC Linac," in Proc. Workshop on 4th Generation Light Sources, M.Cornacchia and H. Winick, eds., SSRL, Feb. 1992. p. 364 ff.)(R. Tatchyn, "Optimal Insertion Device Parameters for SASE FEL Operation," ibid., p. 605 ff.). Over the last several years a wide variety of focusing schemes and configurations have been proposed for undulators of this class, ranging from conventional current-driven quadrupoles external to the undulator magnets(R. Tatchyn, R. Boyce, K. Halbach, H.-D. Nuhn, J. Seeman, H. Winick, and C. Pellegrini, "Design Considerations for a 60 Meter Pure Permanent Magnet Undulator for the SLAC Linac Coherent Light Source (LCLS)," in Proceedings of the 1993 Particle Accelerator Conference, IEEE Catalog No. 93CH3279-7, 1608(1993).) to permanent magnet (PM) lattices inserted into the insertion device gap(R. Tatchyn, "Selected applications of planar permanent magnet multipoles in FEL insertion device design," NIM A341, 449(1994).)(A. A. Varfolomeev, A. H. Hairetdinov, "Advanced hybrid undulator schemes providing enhanced transverse e-beam focusing," ibid., p. 462.)(G. Travish, J. Rosenzweig, "Strong sextupole focussing in planar undulators," NIM A345, 585(1994).). In this paper we present design studies of a flexible hybrid/PM undulator with superimposed planar PM focusing proposed for a 1.5 Angstrom Linac Coherent Light Source (LCLS) undulator(S. Caspi, R. Schlueter, R. Tatchyn, "High-Field Strong-Focusing Undulator Designs for X-Ray Linac Coherent Light Source (LCLS) Applications," Proc. IEEE PAC95, Dallas, TX, May 1-5, 1995, SLAC-PUB-95-6885.)(R. Tatchyn, "Permanent Magnet Edge-Field Quadrupole," US Patent 5,596,304.) driven by an electron beam with a 1 mm-mr normalized emittance(R. Tatchyn et al, NIM A

  15. A soft magnetic underlayer with negative uniaxial magnetocrystalline anisotropy for suppression of spike noise and wide adjacent track erasure in perpendicular recording media

    Science.gov (United States)

    Hashimoto, Atsushi; Saito, Shin; Takahashi, Migaku

    2006-04-01

    The suppression of spike noise and wide adjacent track erasure (WATE) are important technical issues in the development of a perpendicular recording medium (PRM). As a solution to both of these problems, this paper presents a type of soft magnetic underlayer (SUL) with negative uniaxial perpendicular magnetic anisotropy. The magnetic anisotropy is achieved by employing a material with negative uniaxial magnetocrystalline anisotropy (Kugrain). WATE is suppressed in the SUL by realizing wide distribution of magnetic flux below the edge of the return yoke, while spike noise is eliminated by ensuring the formation of a Néel wall instead of a Bloch wall in SUL domains. CoIr with the disordered hcp structure is selected as a negative Kugrain material, and c-plane-oriented CoIr films with various Ir contents are prepared for experimental evaluation. Among the films tested, the CoIr film with 22 at. % Ir is found to provide the minimum Kugrain value of -6×106 ergs/cm3. Under a field applied parallel to the film plane, this film exhibits soft magnetic properties, attributable to the high crystallographic symmetry of the c-plane sheet texture. A PRM fabricated using the CoIr SUL is confirmed to display substantially lower spike noise and WATE compared to conventional structures.

  16. Defining a Cohort of Men Who May Not Require Repeat Prostate Biopsy Based on PCA3 Score and Magnetic Resonance Imaging: The Dual Negative Effect.

    Science.gov (United States)

    Perlis, Nathan; Al-Kasab, Thamir; Ahmad, Ardalan; Goldberg, Estee; Fadak, Kamel; Sayid, Rashid; Finelli, Antonio; Kulkarni, Girish; Hamilton, Rob; Zlotta, Alexandre; Ghai, Sangeet; Fleshner, Neil

    2017-11-23

    Prostate cancer over diagnosis and overtreatment are concerns for clinicians and policy makers. Multiparametric magnetic resonance imaging and the PCA3 (prostate cancer antigen 3) urine test select for clinically significant cases. We explored how well the tests performed together in with previous biopsies. In accordance with ethics committee approval we collected clinicopathological data on all patients in whom a PCA3 test from was done 2011 to June 2016. This included patients on active surveillance for low risk prostate cancer and those without prostate cancer who had previous negative biopsies and suspicion of occult disease. We explored whether age, prostate specific antigen, PCA3 score, multiparametric magnetic resonance imaging, digital rectal examination, family history and prostate size would predict clinically significant prostate cancer on repeat biopsy. The negative predictive value of multiparametric magnetic resonance imaging and PCA3 score was calculated. A total of 470 patients were included in study. The PCA3 score was abnormal at 35 or greater in 32.5% of cases. In the multivariate model including 154 men only age (OR 1.08, 95% CI 1.01-1.16), multiparametric magnetic resonance imaging PI-RADS™ (Prostate Imaging-Reporting and Data System) score 4 (OR 16.6, 95% CI 3.9-70.0) or 5 (OR 28.3, 95% CI 5.7-138) and PCA3 score (OR 2.9, 95% CI 1.0-8.8) predicted clinically significant cancer on biopsy. No patient with negative multiparametric magnetic resonance imaging and a normal PCA3 score had clinically significant prostate cancer on biopsy for a negative predictive value of 100% (p magnetic resonance imaging and PCA3 score) clinically significant prostate cancer was never found on biopsy, which may be unnecessary in this group. This study was limited by its retrospective design, selection bias and lack of cost-effectiveness data. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights

  17. MAVEN Observations of Magnetic Flux Ropes with a Strong Field Amplitude in the Martian Magnetosheath During the ICME Passage on 8 March 2015

    Science.gov (United States)

    Hara, Takuya; Luhmann, Janet G.; Halekas, Jasper S.; Espley, Jared R.; Seki, Kanako; Brain, David A.; Hasegawa, Hiroshi; McFadden, James P.; Mitchell, David L.; Mazelle, Christian; hide

    2016-01-01

    We present initial results of strong field amplitude flux ropes observed by Mars Atmosphere and Volatile EvolutioN (MAVEN) mission around Mars during the interplanetary coronal mass ejection (ICME) passage on 8 March 2015. The observed durations were shorter than 5 s and the magnetic field magnitudes peaked above 80 nT, which is a few times stronger than those usually seen in the magnetosheath barrier. These are the first unique observations that MAVEN detected such flux ropes with a strong field at high altitudes (greater than 5000 km). Across these structures, MAVEN coincidentally measured planetary heavy ions with energies higher than a few keV. The spatial properties inferred from the Grad-Shafranov equation suggest that the speed of the structure can be estimated at least an order of magnitude faster than those previously reported quiet-time counterparts. Hence, the space weather event like the ICME passage can be responsible for generating the observed strong field, fast-traveling flux ropes.

  18. Magnetic resonance imaging of lumbar spine disc diseases. Frequency of false negatives; Imagerie par resonance magnetique pour pathologie discale lombaire. Frequence des faux-negatifs

    Energy Technology Data Exchange (ETDEWEB)

    Berthelot, J.M.; Maugars, Y.; Delecrin, Y.; Caillon, F.; Prost, A. [Hopital Hotel-Dieu de Nantes, 44 (France)

    1995-10-01

    Magnetic resonance imaging (MRI) has had an impressive impact on evaluation of degenerative diseases of the spine. Nevertheless, false negatives can occur on images involving lumbar discs. Degenerative disc diseases documented on discography and/or pathology examination of the discs can go unrecognized. Likewise sensitivity for the detection of protruding disc hernias is not totally satisfactory (20% false negatives). Finally, a magnetic resonance image visualizing displacement of the disc is not specific (10 to 15% false positives); images showing protrusion or hernia can be seen in 30% of asymptomatic patients. Although MRI gives slightly more information than other imaging techniques, false images do exist. Moreover, the usefulness of MRI to demonstrate disc disease in case of a negative CT-scan remains to be demonstrated. (authors). 26 refs.

  19. Study of reaction and heat release from solid combustion in strong magnetic field; Kyojiba wo riyoshita hikinshitsu kotai nensho shori no hanno to netsu no seigy ni kansuru kiso kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Ito, K.; Fujita, O.; Iiya, M.; Kudo, K. [Hokkaido University, Sapporo (Japan)

    1997-02-01

    To establish the inhomogeneous solid combustion control technology, effects of the strong magnetic field on the solid combustion were examined. When applying the sufficiently strong magnetic field, it is possible to control the air flow in combustion field by utilizing the force applying to constituent oxygen with large susceptibility. Based on this possibility, combustion experiments of expanded polystyrene plates were conducted between the magnetic poles of electro-magnet having the maximum flux density of 1 T and the maximum magnetic field gradient of 0.5 T/cm. To observe the effects of magnetic field without the effects of natural convection, combustion experiments of acrylic sheets were conducted between the magnetic poles of electro-magnet having the maximum flux density of 0.6 T and the magnetic field gradient of about 0.1 T/cm under the microgravity conditions between 10{sup -4} and 10{sup -5}g using a microgravity test facility. Consequently, prospective combustion results could be obtained, in which the force of flame received from the magnetic field is almost equivalent to the buoyancy of flame. It was demonstrated that combustion can be controlled by the magnetic field. 1 ref., 3 figs., 1 tab.

  20. Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe1.64Ga0.36O3 oxide

    Directory of Open Access Journals (Sweden)

    R. N. Bhowmik

    2015-06-01

    Full Text Available We have studied current-voltage (I-V characteristics of α-Fe1.64Ga0.36O3, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔVP 0.345(± 0.001 V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (∼500-700%, magnetoresistance (70-135 % and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.

  1. An expansion of the field modulus suitable for the description of strong field gradients in axisymmetric magnetic fields: application to single-sided magnet design, field mapping and STRAFI.

    Science.gov (United States)

    Hugon, Cedric; Aubert, Guy; Sakellariou, Dimitris

    2012-01-01

    Mapping (or plotting) the magnetic field has a critical importance for the achievement of the homogeneous magnetic field necessary to standard MR experiments. A powerful tool for this purpose is the Spherical Harmonic Expansion (SHE), which provides a simple way to describe the spatial variations of a field in free space. Well-controlled non-zero spatial variations of the field are critical to MRI. The resolution of the image is directly related to the strength of the gradient used to encode space. As a result, it is desirable to have strong variations of the field. In that case, the SHE cannot be used as is, because the field modulus variations are affected by the variations of all components of the field. In this paper, we propose a method based on the SHE to characterize such variations, theoretically and experimentally, in the limit of an axisymmetric magnetic field. Practical applications of this method are proposed through the examples of single-sided magnet design and characterization, along with Stray-Field Imaging (STRAFI). Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Epileptic Zone Resection for Magnetic Resonance Imaging-Negative Refractory Epilepsy Originating from the Primary Motor Cortex.

    Science.gov (United States)

    Zhang, Guangming; Meng, Dawei; Liu, Yanwu; Yang, Kai; Chen, Jianwei; Su, Lanmei; Zhang, Zhaozhao; Chen, Guoqiang

    2017-06-01

    Because of the balance between achieving complete seizure freedom and minimizing the postoperative neurologic deficits, surgery for refractory epilepsy originating from the primary motor cortex is difficult. Here, we report the outcomes of surgery for magnetic resonance imaging-negative refractory epilepsy originating from the primary motor cortex in a case series. Nine patients with refractory epilepsy originating from the primary motor cortex underwent intracranial electrodes implantation after preoperative evaluation. Subdural grid electrodes and depth electrodes were implanted through craniotomy assisted by stereotactic technique. We delineated the epileptic zone and executed tailored resection according to results of intracranial electroencephalography and mapping. The patients were followed up for at least 1 year. Muscle strength was evaluated at different postoperative times (day 1, 2 weeks, and 1 year). Regarding seizure outcome at the last follow-up, Engel class I outcome was achieved in 5 patients, class II was achieved in 3 patients, and class III was achieved in 1 patient. All cases had postoperative hemiparesis of different degree on the first day after operation. Three patients experienced distal muscle strength of single limb with grade 3 or lower and had obvious dysfunction at 1 year after operation. Six patients experienced distal muscle strength of grade 4 or 5 (Medical Research Council 6-point scale) and had no obvious dysfunction at that time. Most patients of refractory epilepsy originating from the primary motor cortex were seizure free and had no obvious neurologic deficits at follow-up. Epileptogenic zone resection may not always be contraindicated for patients with nonlesional refractory epilepsy originating from the primary motor cortex. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Magnetic properties of Co-N films deposited by ECR nitrogen/argon plasma with DC negative-biased Co target

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Zhang, Y.C.; Yang, K.; Liu, H.X.; Zhu, X.D., E-mail: xdzhu@ustc.edu.cn; Zhou, H.Y.

    2017-06-01

    Highlights: • A new method of synthesizing Co-N films containing Co{sub 4}N phase. • Tunable magnetic properties achieved in ECR plasma CVD. • The change of magnetic properties is related to atoms mobility on substrate and the concentration of active species in plasma vapor. - Abstract: By introducing DC negative-biased Co target in the Electron Cyclotron Resonance (ECR) nitrogen/argon plasma, the Co-N films containing Co{sub 4}N phase were synthesized on Si(100) substrate. Effects of processing parameters on magnetic properties of the films are investigated. It is found that magnetic properties of Co-N films vary with N{sub 2}/Ar flow ratio, substrate temperature, and target biasing voltage. The saturation magnetization M{sub s} decreased by increasing the N{sub 2}/Ar gas flow ratio or decreasing target biasing voltage, while the coercive field H{sub c} increased, which is ascribed to the variation of relative concentration for N or Co active species in plasma vapor. The magnetic properties present complex dependency with growth temperature, which is related to the atom mobility on the substrate affected by the growth temperature. This study exhibits a potential of ECR plasma chemical vapor deposition to synthesize the interstitial compounds and tune magnetic properties of films.

  4. The First in situ Observation of Kelvin-Helmholtz Waves at High-Latitude Magnetopause during Strongly Dawnward Interplanetary Magnetic Field Conditions

    Science.gov (United States)

    Hwang, K.-J.; Goldstein, M. L.; Kuznetsova, M. M.; Wang, Y.; Vinas, A. F.; Sibeck, D. G.

    2012-01-01

    We report the first in situ observation of high-latitude magnetopause (near the northern duskward cusp) Kelvin-Helmholtz waves (KHW) by Cluster on January 12, 2003, under strongly dawnward interplanetary magnetic field (IMF) conditions. The fluctuations unstable to Kelvin-Helmholtz instability (KHI) are found to propagate mostly tailward, i.e., along the direction almost 90 deg. to both the magnetosheath and geomagnetic fields, which lowers the threshold of the KHI. The magnetic configuration across the boundary layer near the northern duskward cusp region during dawnward IMF is similar to that in the low-latitude boundary layer under northward IMF, in that (1) both magnetosheath and magnetospheric fields across the local boundary layer constitute the lowest magnetic shear and (2) the tailward propagation of the KHW is perpendicular to both fields. Approximately 3-hour-long periods of the KHW during dawnward IMF are followed by the rapid expansion of the dayside magnetosphere associated with the passage of an IMF discontinuity that characterizes an abrupt change in IMF cone angle, Phi = acos (B(sub x) / absolute value of Beta), from approx. 90 to approx. 10. Cluster, which was on its outbound trajectory, continued observing the boundary waves at the northern evening-side magnetopause during sunward IMF conditions following the passage of the IMF discontinuity. By comparing the signatures of boundary fluctuations before and after the IMF discontinuity, we report that the frequencies of the most unstable KH modes increased after the discontinuity passed. This result demonstrates that differences in IMF orientations (especially in f) are associated with the properties of KHW at the high-latitude magnetopause due to variations in thickness of the boundary layer, and/or width of the KH-unstable band on the surface of the dayside magnetopause.

  5. Accurate one-centre method for hydrogen molecular ion calculation using B-spline-type basis sets in strong magnetic fields

    International Nuclear Information System (INIS)

    Zhang Yuexia; Liu Qiang; Shi Tingyun

    2012-01-01

    An accurate one-centre method is here applied to the calculation of the equilibrium distances and the energies for the hydrogen molecular ion in magnetic fields ranging from 10 9 G to 4.414 × 10 13 G. Both the radial and angular wavefunctions were expanded in terms of optimization B-splines. The slow convergence problem in the general one-centre method and singularities at the nuclear positions of the H + 2 were solved well. The accuracy of the one-centre method has been improved in this way. We compared our results with those generated by high-precision methods from published studies. Equilibrium distances of the 1σ g,u , 1π g,u , 1δ g,u and 2σ g states of the H + 2 in strong magnetic fields were found to be accurate to three to four significant digits at least up to 2.35 × 10 12 G, even for the antibonding states 1σ u , 1π g and 1δ u , whose equilibrium distances R eq are very large. (paper)

  6. Strong Visible Light Photocatalytic Activity of Magnetically Recyclable Sol-Gel-Synthesized ZnFe2O4 for Rhodamine B Degradation

    Science.gov (United States)

    Xu, Xiaoli; Xiao, Lingbo; Jia, Yanmin; Hong, Yuantign; Ma, Jiangping; Wu, Zheng

    2018-01-01

    Visible light-responsive ZnFe2O4 photocatalyst with a spinel structure was synthesized via a sol-gel method. The visible light photocatalysis of ZnFe2O4 was investigated by decomposing Rhodamine B (RhB) solution. Under ˜30 min of visible light irradiation, the decomposition ratio of RhB is up to ˜97.4%. The excellent photocatalytic performance of ZnFe2O4 photocatalyst is attributed to the high effective oxidation-reduction reaction caused by light irradiation excitation. With the increase of decomposition time, the wavelength of the maximum absorption peak of RhB solutions shifts from 557 nm to 498 nm ("blue shift"), which is because of the N-deethylation and cleavage of the conjugated chromophore structure of RhB. ZnFe2O4 photocatalyst also exhibits a weak ferromagnetism performance. The decomposition ratio of RhB for the magnetically recycled ZnFe2O4 is ˜94.6%. Strong visible light photocatalysis and convenience of magnetic recycling make ZnFe2O4 promising for photocatalytic applications in dye wastewater treatment.

  7. He{sup 3+}{sub 2} and HeH{sup 2+} molecular ions in a strong magnetic field: The Lagrange-mesh approach

    Energy Technology Data Exchange (ETDEWEB)

    Olivares Pilón, Horacio, E-mail: holivare@ulb.ac.be [Physique Quantique, CP 165/82, Université Libre de Bruxelles, B 1050 Brussels (Belgium)

    2012-04-09

    Accurate calculations for the ground state of the molecular ions He{sup 3+}{sub 2} and HeH{sup 2+} placed in a strong magnetic field B≳10{sup 2} a.u. (≈2.35×10{sup 11} G) using the Lagrange-mesh method are presented. The Born–Oppenheimer approximation of zero order (infinitely massive centers) and the parallel configuration (molecular axis parallel to the magnetic field) are considered. Total energies are found with 9–10 s.d. The obtained results show that the molecular ions He{sup 3+}{sub 2} and HeH{sup 2+} exist at B>100 a.u. and B>1000 a.u., respectively, as predicted in Turbiner and López Vieyra (2007) while a saddle point in the potential curve appears for the first time at B∼80 a.u. and B∼740 a.u., respectively. -- Highlights: ► Application of the Lagrange-mesh method to two exotic molecular systems. ► He{sup 3+}{sub 2} and HeH{sup 2+} exist at B>100 a.u. and B>1000 a.u., respectively. ► Accurate results for the total energy. ► A saddle point in the potential appears at B∼80 a.u. and B∼740 a.u., respectively.

  8. Basal electric and magnetic fields of celestial bodies come from positive-negative charge separation caused by gravitation of quasi-Casimir pressure in weak interaction

    Science.gov (United States)

    Chen, Shao-Guang

    falling and till reach the equilibrium of stable spatial charge distribution, which is just the cause of the geomagnetic field and the geo-electric field (the observational value on the earth surface is about 120 V/m downward equivalent to 500000 Coulomb negative charges in the earth surface). All celestial bodies are gravitation sources and attract the molecules and ions in space to its circumference by the gravitation of own and other celestial bodies, e.g., all planets in the solar system have their own atmospheres. Therefore, the origin mechanism of geo-electric and geomagnetic fields caused by gravitation is very universal, at least it is appli-cable to all the planets in the solar system. For planets, the joint result of the gravitations of the planets and the sun makes the negative charges and dipolar charges distributed in the surfaces of the celestial bodies. The quicker the rotation is, the larger the angular momentum U is, then larger the accompanying current and magnetic moment P, it accord a experiential law found by subsistent observational data of all celestial bodies in solar system: P = -G 1/2 U cos θ / c (1), θ is the angle between the net ν 0 flux direction (mark by CMB) and the rotational axis of celestial body (Chen Shao-Guang, Chinese Science Bulletin, 26,233,1981). Uranian and Neptunian P predicted with Eq.(1) in 1981 are about -3.4•1028 Gs•cm3 and 1.9•1028 Gs•cm3 respectively (use new rotate speed measured by Voyager 2). The P measured by Voyager 2 in 1986 and 1989 are about -1.9 •1028 Gs•cm3 and 1.5•1028 Gs•cm3 respectively (the contribution of quadrupole P is converted into the contribution of dipole P alone). The neutron star pos-sesses much high density and rotational speed because of the conservation of the mass and the angular momentum during the course of the formation, then has strong gravity and largerU. From Eq.(1) there is a larger P and extremely strong surface magnetic field in neutron star. The origin mechanism of

  9. Generalization of transfer matrix method for bi-gyrotropic double-negative magnetic materials in order to use them in multilayer structures.

    Science.gov (United States)

    Zamani, Mehdi; Hajesmaeili, Hamidreza Nezhad; Zandi, Mohammad Hossein

    2017-01-25

    The optical and magneto-optical (MO) response in magnetic multilayer systems is calculated by the transfer matrix method (TMM). In a bi-gyrotropic medium, the electric permittivity (ϵ) and the magnetic permeability (μ) coefficients are in the form of non-diagonal tensors synchronously, in which their non-diagonal elements refer to the existence of anisotropy in such a medium. On the other hand, in a double-negative medium, both the ϵ and μ coefficients are negative. In the present study, we have investigated the combination of these two phenomena and have introduced a TMM-based approach for studying the optical and MO properties of multilayer structures containing bi-gyrotropic double-negative magnetic materials (BDNMMs), whose diagonal and non-diagonal elements refer to the existence of negativity and anisotropy, respectively. We have also investigated the capability of such BDNMM materials in comparison with conventional bi-gyrotropic materials in magneto-photonic crystal structures. As a result, we found that broadening occurs in the optical and magneto-optical responses simultaneously.

  10. Negative permeability from random particle composites

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Shahid, E-mail: shussain2@qinetiq.com

    2017-04-15

    Artificial media, such as those composed of periodically-spaced wires for negative permittivity and split ring resonators for negative permeability have been extensively investigated for negative refractive index (NRI) applications (Smith et al., 2004; Pendry et al., 1999) [1,2]. This paper presents an alternative method for producing negative permeability: granular (or particulate) composites incorporating magnetic fillers. Artificial media, such as split-ring resonators, are designed to produce a magnetic resonance feature, which results in negative permeability over a narrow frequency range about the resonance frequency. The position of the feature is dependent upon the size of the inclusion. The material in this case is anisotropic, such that the feature is only observable when the materials are orientated in a specific direction relative to the applied field. A similar resonance can be generated in magnetic granular (particulate) materials: ferromagnetic resonance from the natural spin resonance of particles. Although the theoretical resonance profiles in granular composites shows the permeability dipping to negative values, this is rarely observed experimentally due to resonance damping effects. Results are presented for iron in spherical form and in flake form, dispersed in insulating host matrices. The two particle shapes show different permeability performance, with the magnetic flakes producing a negative contribution. This is attributed to the stronger coupling with the magnetic field resulting from the high aspect ratio of the flakes. The accompanying ferromagnetic resonance is strong enough to overcome the effects of damping and produce negative permeability. The size of random particle composites is not dictated by the wavelength of the applied field, so the materials are potentially much thinner than other, more traditional artificial composites at microwave frequencies. - Highlights: • Negative permeability from random particle composites is

  11. Efficacy of bilateral repetitive transcranial magnetic stimulation for negative symptoms of schizophrenia: results of a multicenter double-blind randomized controlled trial.

    Science.gov (United States)

    Dlabac-de Lange, J J; Bais, L; van Es, F D; Visser, B G J; Reinink, E; Bakker, B; van den Heuvel, E R; Aleman, A; Knegtering, H

    2015-04-01

    Few studies have investigated the efficacy of repetitive transcranial magnetic stimulation (rTMS) treatment for negative symptoms of schizophrenia, reporting inconsistent results. We aimed to investigate whether 10 Hz stimulation of the bilateral dorsolateral prefrontal cortex during 3 weeks enhances treatment effects. A multicenter double-blind randomized controlled trial was performed in 32 patients with schizophrenia or schizo-affective disorder, and moderate to severe negative symptoms [Positive and Negative Syndrome Scale (PANSS) negative subscale ⩾15]. Patients were randomized to a 3-week course of active or sham rTMS. Primary outcome was severity of negative symptoms as measured with the Scale for the Assessment of Negative Symptoms (SANS) and the PANSS negative symptom score. Secondary outcome measures included cognition, insight, quality of life and mood. Subjects were followed up at 4 weeks and at 3 months. For analysis of the data a mixed-effects linear model was used. A significant improvement of the SANS in the active group compared with sham up to 3 months follow-up (p = 0.03) was found. The PANSS negative symptom scores did not show a significant change (p = 0.19). Of the cognitive tests, only one showed a significant improvement after rTMS as compared with sham. Finally, a significant change of insight was found with better scores in the treatment group. Bilateral 10 Hz prefrontal rTMS reduced negative symptoms, as measured with the SANS. More studies are needed to investigate optimal parameters for rTMS, the cognitive effects and the neural basis.

  12. Construction of three-dimensional graphene interfaces into carbon fiber textiles for increasing deposition of nickel nanoparticles: flexible hierarchical magnetic textile composites for strong electromagnetic shielding

    Science.gov (United States)

    Bian, Xing-Ming; Liu, Lin; Li, Hai-Bing; Wang, Chan-Yuan; Xie, Qing; Zhao, Quan-Liang; Bi, Song; Hou, Zhi-Ling

    2017-01-01

    Since manipulating electromagnetic waves with electromagnetic active materials for environmental and electric engineering is a significant task, here a novel prototype is reported by introducing reduced graphene oxide (RGO) interfaces in carbon fiber (CF) networks for a hierarchical carbon fiber/reduced graphene oxide/nickel (CF-RGO-Ni) composite textile. Upon charaterizations of the microscopic morphologies, electrical and magnetic properties, the presence of three-dimensional RGO interfaces and bifunctional nickel nanoparticles substantially influences the related physical properties in the resulting hierarchical composite textiles. Eletromagnetic interference (EMI) shielding performance suggests that the hierarchical composite textiles hold a strong shielding effectiveness greater than 61 dB, showing greater advantages than conventional polymeric and foamy shielding composites. As a polymer-free lightweight structure, flexible CF-RGO-Ni composites of all electromagnetic active components offer unique understanding of the multi-scale and multiple mechanisms in electromagnetic energy consumption. Such a novel prototype of shielding structures along with convenient technology highlight a strategy to achieve high-performance EMI shielding, coupled with a universal approach for preparing advanced lightweight composites with graphene interfaces.

  13. Simple anthropometric measures correlate with metabolic risk indicators as strongly as magnetic resonance imaging-measured adipose tissue depots in both HIV-infected and control subjects.

    Science.gov (United States)

    Scherzer, Rebecca; Shen, Wei; Bacchetti, Peter; Kotler, Donald; Lewis, Cora E; Shlipak, Michael G; Heymsfield, Steven B; Grunfeld, Carl

    2008-06-01

    Studies in persons without HIV infection have compared percentage body fat (%BF) and waist circumference as markers of risk for the complications of excess adiposity, but only limited study has been conducted in HIV-infected subjects. We compared anthropometric and magnetic resonance imaging (MRI)-based adiposity measures as correlates of metabolic complications of adiposity in HIV-infected and control subjects. The study was a cross-sectional analysis of 666 HIV-positive and 242 control subjects in the Fat Redistribution and Metabolic Change in HIV Infection (FRAM) study assessing body mass index (BMI), waist (WC) and hip (HC) circumferences, waist-to-hip ratio (WHR), %BF, and MRI-measured regional adipose tissue. Study outcomes were 3 metabolic risk variables [homeostatic model assessment (HOMA), triglycerides, and HDL cholesterol]. Analyses were stratified by sex and HIV status and adjusted for demographic, lifestyle, and HIV-related factors. In HIV-infected and control subjects, univariate associations with HOMA, triglycerides, and HDL were strongest for WC, MRI-measured visceral adipose tissue, and WHR; in all cases, differences in correlation between the strongest measures for each outcome were small (r HDL, WC appeared to be the best anthropometric correlate of metabolic complications, whereas, for triglycerides, the best was WHR. Relations of simple anthropometric measures with HOMA, triglycerides, and HDL cholesterol are approximately as strong as MRI-measured whole-body adipose tissue depots in both HIV-infected and control subjects.

  14. Functionalization of Strongly Interacting Magnetic Nanocubes with (Thermo)responsive Coating and their Application in Hyperthermia and Heat-Triggered Drug Delivery

    KAUST Repository

    Kakwere, Hamilton

    2015-04-03

    Herein we prepare nanohybrids by incorporating iron oxide nanocubes (cubic-IONPs) within a thermo-responsive polymer shell that can act as drug carriers for doxorubicin(doxo). The cubic-shaped nanoparticles employed are at the interface between superparamagnetic and ferromagnetic behavior and have an exceptionally high specific absorption rate (SAR) but their functionalization is extremely challenging compared to bare superparamagnetic iron oxide nanoparticles as they strongly interact with each other. By conducting the polymer grafting reaction using reversible addition-fragmentation chain transfer (RAFT) polymerization in a viscous solvent medium, we have here developed a facile approach to decorate the nanocubes with stimuli-responsive polymers. When the thermo-responsive shell is composed of poly(N-isopropyl acrylamide-co-polyethylene glycolmethylether acrylate), nanohybrids have a phase transition temperature, the lower critical solution temperature (LCST), above 37 °C in physiological conditions. Doxo loaded nanohybrids exhibited a negligible drug release below 37 °C but showed a consistent release of their cargo on demand by exploiting the capability of the nanocubes to generate heat under an alternating magnetic field (AMF). Moreover, the drug free nanocarrier does not exhibit cytotoxicity even when administered at high concentration of nanocubes (1g/L of iron) and internalized at high extent (260 pg of iron per cell). We have also implemented the synthesis protocol to decorate the surface of nanocubes with poly(vinylpyridine) polymer and thus prepare pH-responsive shell coated nanocubes.

  15. The nuclear magnetic moment of 208Bi and its relevance for a test of bound-state strong-field QED

    Science.gov (United States)

    Schmidt, S.; Billowes, J.; Bissell, M. L.; Blaum, K.; Garcia Ruiz, R. F.; Heylen, H.; Malbrunot-Ettenauer, S.; Neyens, G.; Nörtershäuser, W.; Plunien, G.; Sailer, S.; Shabaev, V. M.; Skripnikov, L. V.; Tupitsyn, I. I.; Volotka, A. V.; Yang, X. F.

    2018-04-01

    The hyperfine structure splitting in the 6p3 3/2 4S → 6p2 7 s 1/2 4P transition at 307 nm in atomic 208Bi was measured with collinear laser spectroscopy at ISOLDE, CERN. The hyperfine A and B factors of both states were determined with an order of magnitude improved accuracy. Based on these measurements, theoretical input for the hyperfine structure anomaly, and results from hyperfine measurements on hydrogen-like and lithium-like 209Bi80+,82+, the nuclear magnetic moment of 208Bi has been determined to μ (208Bi) = + 4.570 (10)μN. Using this value, the transition energy of the ground-state hyperfine splitting in hydrogen-like and lithium-like 208Bi80+,82+ and their specific difference of -67.491(5)(148) meV are predicted. This provides a means for an experimental confirmation of the cancellation of nuclear structure effects in the specific difference in order to exclude such contributions as the cause of the hyperfine puzzle, the recently reported 7-σ discrepancy between experiment and bound-state strong-field QED calculations of the specific difference in the hyperfine structure splitting of 209Bi80+,82+.

  16. Fast ignition realization experiment with high-contrast kilo-joule peta-watt LFEX laser and strong external magnetic field

    Science.gov (United States)

    Fujioka, Shinsuke; Arikawa, Yasunobu; Kojima, Sadaoki; Johzaki, Tomoyuki; Nagatomo, Hideo; Sawada, Hiroshi; Lee, Seung Ho; Shiroto, Takashi; Ohnishi, Naofumi; Morace, Alessio; Vaisseau, Xavier; Sakata, Shohei; Abe, Yuki; Matsuo, Kazuki; Farley Law, King Fai; Tosaki, Shota; Yogo, Akifumi; Shigemori, Keisuke; Hironaka, Yoichiro; Zhang, Zhe; Sunahara, Atsushi; Ozaki, Tetsuo; Sakagami, Hitoshi; Mima, Kunioki; Fujimoto, Yasushi; Yamanoi, Kohei; Norimatsu, Takayoshi; Tokita, Shigeki; Nakata, Yoshiki; Kawanaka, Junji; Jitsuno, Takahisa; Miyanaga, Noriaki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Kondo, Kotaro; Bailly-Grandvaux, Mathieu; Bellei, Claudio; Santos, João Jorge; Azechi, Hiroshi

    2016-05-01

    plasma. Following the above improvements, conversion of 13% of the LFEX laser energy to a low energy portion of the REB, whose slope temperature is 0.7 MeV, which is close to the ponderomotive scaling value, was achieved. To meet the second requirement, the compression of a solid spherical ball with a diameter of 200-μm to form a dense core with an areal density of ˜0.07 g/cm2 was induced by a laser-driven spherically converging shock wave. Converging shock compression is more hydrodynamically stable compared to shell implosion, while a hot spot cannot be generated with a solid ball target. Solid ball compression is preferable also for compressing an external magnetic field to collimate the REB to the fuel core, due to the relatively small magnetic Reynolds number of the shock compressed region. To meet the third requirement, we have generated a strong kilo-tesla magnetic field using a laser-driven capacitor-coil target. The strength and time history of the magnetic field were characterized with proton deflectometry and a B-dot probe. Guidance of the REB using a 0.6-kT field in a planar geometry has been demonstrated at the LULI 2000 laser facility. In a realistic FI scenario, a magnetic mirror is formed between the REB generation point and the fuel core. The effects of the strong magnetic field on not only REB transport but also plasma compression were studied using numerical simulations. According to the transport calculations, the heating efficiency can be improved from 0.4% to 4% by the GEKKO and LFEX laser system by meeting the three requirements described above. This efficiency is scalable to 10% of the heating efficiency by increasing the areal density of the fuel core.

  17. Magnets

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires with one end of each wire held in a non-magnetic spacer, the other ends of the wires being brought to a pinch, and connected to a magnetic core. The wires may be embedded in a synthetic resin and the magnetisation and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece. (author)

  18. Diamagnetism of 2D-fermions in the strong nonhomogeneous static magnetic field B = B(0,0,1/cosh2(x-x0/δ))

    International Nuclear Information System (INIS)

    Hudak, O.

    1991-09-01

    We study diamagnetism of a gas of fermions moving in a nonhomogeneous magnetic field B = B(0,0,1/cosh 2 (x-x 0 /δ)). The gas magnetization, the static magnetic susceptibility, the chemical potential and the gas compressibility are discussed and compared with the uniform field case. (author). 5 refs

  19. Modeling of negative ion extraction from a magnetized plasma source: Derivation of scaling laws and description of the origins of aberrations in the ion beam

    Science.gov (United States)

    Fubiani, G.; Garrigues, L.; Boeuf, J. P.

    2018-02-01

    We model the extraction of negative ions from a high brightness high power magnetized negative ion source. The model is a Particle-In-Cell (PIC) algorithm with Monte-Carlo Collisions. The negative ions are generated only on the plasma grid surface (which separates the plasma from the electrostatic accelerator downstream). The scope of this work is to derive scaling laws for the negative ion beam properties versus the extraction voltage (potential of the first grid of the accelerator) and plasma density and investigate the origins of aberrations on the ion beam. We show that a given value of the negative ion beam perveance correlates rather well with the beam profile on the extraction grid independent of the simulated plasma density. Furthermore, the extracted beam current may be scaled to any value of the plasma density. The scaling factor must be derived numerically but the overall gain of computational cost compared to performing a PIC simulation at the real plasma density is significant. Aberrations appear for a meniscus curvature radius of the order of the radius of the grid aperture. These aberrations cannot be cancelled out by switching to a chamfered grid aperture (as in the case of positive ions).

  20. Simple anthropometric measures correlate with metabolic risk indicators as strongly as magnetic resonance imaging–measured adipose tissue depots in both HIV-infected and control subjects2

    Science.gov (United States)

    Scherzer, Rebecca; Shen, Wei; Bacchetti, Peter; Kotler, Donald; Lewis, Cora E; Shlipak, Michael G; Heymsfield, Steven B

    2008-01-01

    Background Studies in persons without HIV infection have compared percentage body fat (%BF) and waist circumference as markers of risk for the complications of excess adiposity, but only limited study has been conducted in HIV-infected subjects. Objective We compared anthropometric and magnetic resonance imaging (MRI)–based adiposity measures as correlates of metabolic complications of adiposity in HIV-infected and control subjects. Design The study was a cross-sectional analysis of 666 HIV-positive and 242 control subjects in the Fat Redistribution and Metabolic Change in HIV Infection (FRAM) study assessing body mass index (BMI), waist (WC) and hip (HC) circumferences, waist-to-hip ratio (WHR), %BF, and MRI-measured regional adipose tissue. Study outcomes were 3 metabolic risk variables [homeostatic model assessment (HOMA), triglycerides, and HDL cholesterol]. Analyses were stratified by sex and HIV status and adjusted for demographic, lifestyle, and HIV-related factors. Results In HIV-infected and control subjects, univariate associations with HOMA, triglycerides, and HDL were strongest for WC, MRI-measured visceral adipose tissue, and WHR; in all cases, differences in correlation between the strongest measures for each outcome were small (r ≤ 0.07). Multivariate adjustment found no significant difference for optimally fitting models between the use of anthropometric and MRI measures, and the magnitudes of differences were small (adjusted R2 ≤ 0.06). For HOMA and HDL, WC appeared to be the best anthropometric correlate of metabolic complications, whereas, for triglycerides, the best was WHR. Conclusion Relations of simple anthropometric measures with HOMA, triglycerides, and HDL cholesterol are approximately as strong as MRI-measured whole-body adipose tissue depots in both HIV-infected and control subjects. PMID:18541572

  1. Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy,and Related Fields

    International Nuclear Information System (INIS)

    Grisham, L.R.; Kwan, J.W.

    2008-01-01

    Some years ago it was suggested that halogen negative ions could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons - can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion - ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.

  2. Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy, and Related Fields

    Energy Technology Data Exchange (ETDEWEB)

    L. Grisham and J.W. Kwan

    2008-08-12

    Some years ago it was suggested that halogen negative ions [1] could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons -- can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion-ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.

  3. Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy, and Related Fields

    Energy Technology Data Exchange (ETDEWEB)

    Grisham, L.R.; Kwan, J.W.

    2008-08-01

    Some years ago it was suggested that halogen negative ions [1]could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, and with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons -- can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion-ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.

  4. Comparison of Superparamagnetic and Ultrasmall Superparamagnetic Iron Oxide Cell Labeling for Tracking Green Fluorescent Protein Gene Marker with Negative and Positive Contrast Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Zhuoli Zhang

    2009-05-01

    Full Text Available The objectives of this study were to investigate the feasibility of imaging green fluorescent protein (GFP-expressing cells labeled with iron oxide nanoparticles with the fast low-angle positive contrast steady-state free precession (FLAPS method and to compare them with the traditional negative contrast technique. The GFP-R3230Ac cell line (GFP cell was incubated for 24 hours using 20 μg Fe/mL concentration of superparamagnetic iron oxide (SPIO and ultrasmall superparamagnetic iron oxide (USPIO nanoparticles. Cell samples were prepared for iron content analysis and cell function evaluation. The labeled cells were imaged using positive contrast with FLAPS imaging, and FLAPS images were compared with negative contrast T2*-weighted images. The results demonstrated that SPIO and USPIO labeling of GFP cells had no effect on cell function or GFP expression. Labeled cells were successfully imaged with both positive and negative contrast magnetic resonance imaging (MRI. The labeled cells were observed as a narrow band of signal enhancement surrounding signal voids in FLAPS images and were visible as signal voids in T2*-weighted images. Positive contrast and negative contrast imaging were both valuable for visualizing labeled GFP cells. MRI of labeled cells with GFP expression holds potential promise for monitoring the temporal and spatial migration of gene markers and cells, thereby enhancing the understanding of cell- and gene-based therapeutic strategies.

  5. Comparison of superparamagnetic and ultrasmall superparamagnetic iron oxide cell labeling for tracking green fluorescent protein gene marker with negative and positive contrast magnetic resonance imaging.

    Science.gov (United States)

    Zhang, Zhuoli; Dharmakumar, Rohan; Mascheri, Nicole; Fan, Zhaoyang; Wu, Shengyong; Li, Debiao

    2009-01-01

    The objectives of this study were to investigate the feasibility of imaging green fluorescent protein (GFP)-expressing cells labeled with iron oxide nanoparticles with the fast low-angle positive contrast steady-state free precession (FLAPS) method and to compare them with the traditional negative contrast technique. The GFP-R3230Ac cell line (GFP cell) was incubated for 24 hours using 20 microg Fe/mL concentration of superparamagnetic iron oxide (SPIO) and ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles. Cell samples were prepared for iron content analysis and cell function evaluation. The labeled cells were imaged using positive contrast with FLAPS imaging, and FLAPS images were compared with negative contrast T2*-weighted images. The results demonstrated that SPIO and USPIO labeling of GFP cells had no effect on cell function or GFP expression. Labeled cells were successfully imaged with both positive and negative contrast magnetic resonance imaging (MRI). The labeled cells were observed as a narrow band of signal enhancement surrounding signal voids in FLAPS images and were visible as signal voids in T2*-weighted images. Positive contrast and negative contrast imaging were both valuable for visualizing labeled GFP cells. MRI of labeled cells with GFP expression holds potential promise for monitoring the temporal and spatial migration of gene markers and cells, thereby enhancing the understanding of cell- and gene-based therapeutic strategies.

  6. Comparison of Superparamagnetic and Ultrasmall Superparamagnetic Iron Oxide Cell Labeling for Tracking Green Fluorescent Protein Gene Marker with Negative and Positive Contrast Magnetic Resonance Imaging

    Science.gov (United States)

    Zhang, Zhuoli; Dharmakumar, Rohan; Mascheri, Nicole; Fan, Zhaoyang; Wu, Shengyong; Li, Debiao

    2010-01-01

    The objectives of this study were to investigate the feasibility of imaging green fluorescent protein (GFP)-expressing cells labeled with iron oxide nanoparticles with the fast low-angle positive contrast steady-state free precession (FLAPS) method and to compare them with the traditional negative contrast technique. The GFP-R3230Ac cell line (GFP cell) was incubated for 24 hours using 20 μg Fe/mL concentration of superparamagnetic iron oxide (SPIO) and ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles. Cell samples were prepared for iron content analysis and cell function evaluation. The labeled cells were imaged using positive contrast with FLAPS imaging, and FLAPS images were compared with negative contrast T2*-weighted images. The results demonstrated that SPIO and USPIO labeling of GFP cells had no effect on cell function or GFP expression. Labeled cells were successfully imaged with both positive and negative contrast magnetic resonance imaging (MRI). The labeled cells were observed as a narrow band of signal enhancement surrounding signal voids in FLAPS images and were visible as signal voids in T2*-weighted images. Positive contrast and negative contrast imaging were both valuable for visualizing labeled GFP cells. MRI of labeled cells with GFP expression holds potential promise for monitoring the temporal and spatial migration of gene markers and cells, thereby enhancing the understanding of cell- and gene-based therapeutic strategies. PMID:19723472

  7. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  8. 3D numerical simulations of negative hydrogen ion extraction using realistic plasma parameters, geometry of the extraction aperture and full 3D magnetic field map

    Science.gov (United States)

    Mochalskyy, S.; Wünderlich, D.; Ruf, B.; Franzen, P.; Fantz, U.; Minea, T.

    2014-02-01

    Decreasing the co-extracted electron current while simultaneously keeping negative ion (NI) current sufficiently high is a crucial issue on the development plasma source system for ITER Neutral Beam Injector. To support finding the best extraction conditions the 3D Particle-in-Cell Monte Carlo Collision electrostatic code ONIX (Orsay Negative Ion eXtraction) has been developed. Close collaboration with experiments and other numerical models allows performing realistic simulations with relevant input parameters: plasma properties, geometry of the extraction aperture, full 3D magnetic field map, etc. For the first time ONIX has been benchmarked with commercial positive ions tracing code KOBRA3D. A very good agreement in terms of the meniscus position and depth has been found. Simulation of NI extraction with different e/NI ratio in bulk plasma shows high relevance of the direct negative ion extraction from the surface produced NI in order to obtain extracted NI current as in the experimental results from BATMAN testbed.

  9. Negative permeability from random particle composites

    Science.gov (United States)

    Hussain, Shahid

    2017-04-01

    Artificial media, such as those composed of periodically-spaced wires for negative permittivity and split ring resonators for negative permeability have been extensively investigated for negative refractive index (NRI) applications (Smith et al., 2004; Pendry et al., 1999) [1,2]. This paper presents an alternative method for producing negative permeability: granular (or particulate) composites incorporating magnetic fillers. Artificial media, such as split-ring resonators, are designed to produce a magnetic resonance feature, which results in negative permeability over a narrow frequency range about the resonance frequency. The position of the feature is dependent upon the size of the inclusion. The material in this case is anisotropic, such that the feature is only observable when the materials are orientated in a specific direction relative to the applied field. A similar resonance can be generated in magnetic granular (particulate) materials: ferromagnetic resonance from the natural spin resonance of particles. Although the theoretical resonance profiles in granular composites shows the permeability dipping to negative values, this is rarely observed experimentally due to resonance damping effects. Results are presented for iron in spherical form and in flake form, dispersed in insulating host matrices. The two particle shapes show different permeability performance, with the magnetic flakes producing a negative contribution. This is attributed to the stronger coupling with the magnetic field resulting from the high aspect ratio of the flakes. The accompanying ferromagnetic resonance is strong enough to overcome the effects of damping and produce negative permeability. The size of random particle composites is not dictated by the wavelength of the applied field, so the materials are potentially much thinner than other, more traditional artificial composites at microwave frequencies.

  10. The robustness of high-Tc superconductivity in underdoped YBa2Cu3O6+x investigated in under strong magnetic fields

    Science.gov (United States)

    Harrison, Neil; Hsu, Y.-T.; Hartstein, M.; Chan, M.; Porras, J.; Loew, T.; Le Tacon, M.; Lonzarich, G.; Keimer, B.; Flux, V.; Sebastian, S.

    A central unresolved mystery in high-Tc superconductivity is whether the pairing amplitude is small in the underdoped regime and relates to the superfluid density or whether it is large and relate to the intrinsic energy scales of the Mott insulating parent state. The magnetic field provides a sensitive probe of the pairing amplitude. However, experimental probes of the extent of the vortex state in temperature and magnetic field have thus far been indirect and hence subject to debate. Here we report measurements over a broad range of temperature and magnetic fields which we use to probe the extent of the vortex region in underdoped YBa2Cu3O6+x. and its interplay with quantum oscillations. N.H. acknowledges UU DOE BES Support for ''Science of 100 Tesla''.

  11. Subclinical abnormal gyration pattern, a potential anatomic marker of epileptogenic zone in patients with magnetic resonance imaging negative frontal lobe epilepsy

    International Nuclear Information System (INIS)

    Regis, J.; Tamura, M.; Park, M.C.; McGonigal, A.; Riviere, D.; Coulon, O.; Bartolomei, F.; Girard, N.; Figarella-Branger, D.; Chauvel, P.; Mangin, J.F.

    2011-01-01

    Background: Epilepsy surgery for magnetic resonance imaging (MRI)-negative patients has a less favorable outcome. Objective: Detection of subclinical abnormal gyration (SAG) patterns and their potential contribution to assessment of the topography of the epileptogenic zone (EZ) is addressed in MRI-negative patients with frontal lobe epilepsy. Methods: Between September 1998 and July 2005, 12 MRI-negative frontal lobe epilepsy patients underwent stereo-electro-encephalography with postcorticectomy follow-up of longer than 1 year (average, 3.3 years). Original software (BrainVISA/Anatomist, http://brainvisa.info) trained on a database of normal volunteers was used to determine which sulci had morphology out of the normal range (SAG). Topography of the EZ, SAG pattern, corticectomy, postoperative seizure control, and histopathology were analyzed. Results: At last follow-up, 8 of 12 patients (66.7%) were Engel class I (7 IA and 1 IB), 2 class II, and 2 class IV. Small focal cortical dysplasia was histologically diagnosed in 9 of the 12 patients (75%), including 7 of 8 seizure-free patients (87.5%). A SAG pattern was found to be in the EZ area in 9 patients (75%), in the ipsilateral frontal lobe out of the EZ in 2, and limited to the contralateral hemisphere in 1. Conclusion: SAG patterns appear to be associated with the topography of the EZ in MRI-negative frontal lobe epilepsy and may have a useful role in preoperative assessment. Small focal cortical dysplasia not detected with MRI is often found on histopathological examination, particularly in the depth of the posterior part of the superior frontal sulcus and intermediate frontal sulcus, suggesting a specific developmental critical zone in these locations. (authors)

  12. Two-dimensional superconducting state of monolayer Pb films grown on GaAs(110) in a strong parallel magnetic field.

    Science.gov (United States)

    Sekihara, Takayuki; Masutomi, Ryuichi; Okamoto, Tohru

    2013-08-02

    Two-dimensional (2D) superconductivity was studied by magnetotransport measurements on single-atomic-layer Pb films on a cleaved GaAs(110) surface. The superconducting transition temperature shows only a weak dependence on the parallel magnetic field up to 14T, which is higher than the Pauli paramagnetic limit. Furthermore, the perpendicular-magnetic-field dependence of the sheet resistance is almost independent of the presence of the parallel field component. These results are explained in terms of an inhomogeneous superconducting state predicted for 2D metals with a large Rashba spin splitting.

  13. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  14. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  15. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  16. Magnetic structure of YMn12

    International Nuclear Information System (INIS)

    Deportes, J.; Givord, D.

    1976-01-01

    YMn 12 crystallizes in the I 4 /mmm tetragonal body-centred structure. Neutron diffraction experiments give evidence for an anti-ferromagnetic structure (Tsub(N) = 120 K) in the tetragonal cell. The magnetic structure has been determined with the help of group theory. The mean Mn magnetic moment is 0.4μsub(B). In spite of the non-colinear arrangement of magnetic moments strong negative anisotropic interactions are evidenced. As it is observed in pure Mn and in rare earth-Fe compounds, these interactions are strongly distance dependent. (author)

  17. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  18. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  19. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  20. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  1. Radio frequency self-resonant coil for contactless AC-conductivity in 100 T class ultra-strong pulse magnetic fields

    Science.gov (United States)

    Nakamura, D.; Altarawneh, M. M.; Takeyama, S.

    2018-03-01

    A contactless measurement system of electrical conductivity was developed for application under pulsed high magnetic fields over 100 T by using a self-resonant-type, high-frequency circuit. Electromagnetic fields in the circuit were numerically analysed by the finite element method, to show how the resonant power spectra of the circuit depends on the electrical conductivity of a sample set on the probe-coil. The performance was examined using a high-temperature cuprate superconductor, La2-x Sr x CuO4, in magnetic fields up to 102 T with a high frequency of close to 800 MHz. As a result, the upper critical field could be determined with a good signal-to-noise ratio.

  2. Highly ionized plasma plume generation by long-pulse CO2 laser irradiation of solid targets in strong axial magnetic fields

    International Nuclear Information System (INIS)

    Hoffman, A.L.; Crawford, E.A.

    1982-01-01

    The present work utilizes high f number optics and is directed primarily at controlling the conditions in the magnetically confined plume. Typically, fully ionized carbon plasmas have been produced with 10 18 cm -3 electron densities and 100 to 150 eV electron temperatures. These carbon plasmas have been doped with high Z atoms in order to study ionization and emission rates at the above conditions

  3. Impact of nucleic acid self-alignment in a strong magnetic field on the interpretation of indirect spin-spin interactions

    Czech Academy of Sciences Publication Activity Database

    Vavrinská, A.; Zelinka, J.; Šebera, Jakub; Sychrovský, Vladimír; Fiala, R.; Boelens, R.; Sklenář, V.; Trantírek, L.

    2016-01-01

    Roč. 64, č. 1 (2016), s. 53-62 ISSN 0925-2738 R&D Projects: GA ČR GA13-27676S Grant - others:AV ČR(CZ) M200551205 Institutional support: RVO:61388963 Keywords : NMR * DFT calculations * spin-spin interactions * magnetic field Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.410, year: 2016 http://link.springer.com/article/10.1007/s10858-015-0005-x

  4. Strong-coupling phases of the spin-orbit-coupled spin-1 Bose-Hubbard chain: Odd-integer Mott lobes and helical magnetic phases

    Science.gov (United States)

    Pixley, J. H.; Cole, William S.; Spielman, I. B.; Rizzi, Matteo; Das Sarma, S.

    2017-10-01

    We study the odd-integer filled Mott phases of a spin-1 Bose-Hubbard chain and determine their fate in the presence of a Raman induced spin-orbit coupling which has been achieved in ultracold atomic gases; this system is described by a quantum spin-1 chain with a spiral magnetic field. The spiral magnetic field initially induces helical order with either ferromagnetic or dimer order parameters, giving rise to a spiral paramagnet at large field. The spiral ferromagnet-to-paramagnet phase transition is in a universality class with critical exponents associated with the divergence of the correlation length ν ≈2 /3 and the order-parameter susceptibility γ ≈1 /2 . We solve the effective spin model exactly using the density-matrix renormalization group, and compare with both a large-S classical solution and a phenomenological Landau theory. We discuss how these exotic bosonic magnetic phases can be produced and probed in ultracold atomic experiments in optical lattices.

  5. Sensitivity degradation of an anger camera operated in SPECT-like mode under the influence of a strong external magnetic field

    International Nuclear Information System (INIS)

    Galiano, Eduardo; Aldarwish, Huda

    2014-01-01

    The purpose of this work was to experimentally determine the degradation in sensitivity of an Anger camera rotated in SPECT-like orbits around the transverse and sagittal planes of the magnetic field produced by a conventional, dual coil, 1 T electromagnet. A 74 photomultiplier Siemens Basicam Anger camera with a 29 cm radius crystal and an Isotrak 35 cm diameter, 46 MBq (1.25 mCi), Co-57 disk source attached to a low energy general purpose collimator, were used for all measurements. A custom made, air-cooled, dual coil, 1 T electromagnet was used to produce the external magnetic field. A map of the magnetic field was obtained by taking intensity measurements around the sagittal and transverse planes of the magnet. Camera sensitivity – defined as the measured count rate for a given activity of a radionuclide in a defined geometry – was first measured around the transverse plane at angles of 0°, 90°, and 270°, with, and without, the magnetic field present. At each angle, three 30 min measurements were made and the average count rate was calculated. A similar protocol was used for measurements upon rotation in the sagittal plane: counts per 30 min interval were measured for 20 angles, with a 15° increment between measurements. Camera sensitivity as a function of field strength was also determined by collecting counts over 30 min intervals at a fixed angle (90°) with magnet currents of 0.00 A, 2.65 A, and 5.30 A. In the transverse plane, at 0° under a field intensity of 21 mT, the loss in sensitivity was 18.14%, at 90° (B=37 mT) the loss was 30.5%, and at 270° (B=38 mT) the loss was 34.9%. Thus for rotation in the transverse plane, the sensitivity is monotonically reduced with an increase in field intensity. On rotation in the sagittal plane, sensitivity degradation ranged between 50.3% at a 22° angle, and 59.1% at 315°. Broad sensitivity peaks were observed at 105° and 195°, with minima at 60°, 135°, and 260°, consistent with our theoretical

  6. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  7. Halbach Magnets for CBETA

    Energy Technology Data Exchange (ETDEWEB)

    Trbojevic, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-01-19

    A principle of the non-scaling Fixed Field Alternating Gradient (NS-FFAG) is that different energy beam has orbit oscillations Δx around the central circular orbit in both positive and negative direction within a small radial aperture as: Δx=Dx*δp/p. For the central circular orbit Δx=0, or for the combined function magnets the field is equal to Bo (B (x) = Bo + G* x). The smallest orbit offsets Δx are obtained when the defocusing magnet provides most of the bending for the central energy, while the focusing magnet could be even the regular quadrupole with the central orbit in the middle. Stable orbits for a very large energy range [in the case of CBETA this is 4 times in energy], is obtained using opposite polarity magnets producing linear magnetic fields, small dispersion, and very strong focusing.

  8. Halbach Magnets for CBETA

    Energy Technology Data Exchange (ETDEWEB)

    Trbojevic, D. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-12-30

    A principle of the non-scaling Fixed Field Alternating Gradient (NS-FFAG) is that different energy beam has orbit oscillations Δx around the central circular orbit in both positive and negative direction within a small radial aperture as: Δx=Dx*δp/p. For the central circular orbit Δx=0, or for the combined function magnets the field is equal to Bo (B (x) = Bo + G*x). The smallest orbit offsets Δx are obtained when the defocusing magnet provides most of the bending for the central energy, while the focusing magnet could be even the regular quadrupole with the central orbit in the middle. Stable orbits for a very large energy range [in the case of CBETA this is 4 times in energy], is obtained using opposite polarity magnets producing linear magnetic fields, small dispersion, and very strong focusing.

  9. Negating the Verum

    DEFF Research Database (Denmark)

    Ørsnes, Bjarne

    2012-01-01

    an (aboutness-)topic. The negation of a verum predicate explains why preposed negation—like other constructions with verum-focus—fails to license strong negative polarity items and fails to rule out positive ones. The lack of a topic explains why preposed negation is preferred with non-referential subjects...

  10. Spin dynamics in the strongly magnetically frustrated compounds YBaCo{sub 3}AlO{sub 7} and YBaCo{sub 3}FeO{sub 7} probed by NMR and ESR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Iakovleva, Margarita [IFW Dresden, Dresden (Germany); TU Dresden, Dresden (Germany); E. K. Zavoisky Physical-Technical Institute, Kazan (Russian Federation); Zeisner, Julian; Zimmermann, Stephan; Buechner, Bernd [IFW Dresden, Dresden (Germany); TU Dresden, Dresden (Germany); Valldor, Martin [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Vavilova, Evgeniia [E. K. Zavoisky Physical-Technical Institute, Kazan (Russian Federation); Grafe, Hans-Joachim; Alfonsov, Alexey; Kataev, Vladislav [IFW Dresden, Dresden (Germany)

    2016-07-01

    In the Swedenborgite type compounds YBaCo{sub 3}AlO{sub 7} and YBaCo{sub 3}FeO{sub 7} the magnetic lattice can be described as a stacking of kagome layers, where unconventional ground states such as a spin liquid state can be expected due to the strong geometrical frustration. We performed a combined experimental study of magnetic properties of single crystals of YBaCo{sub 3}AlO{sub 7} and YBaCo{sub 3}FeO{sub 7} with high field ESR and high field NMR spectroscopy. The experimental results show the occurrence of short-range quasi static electron spin correlations at T{sup *} ∼ 22 K for YBaCo{sub 3}AlO{sub 7} and T{sup *} ∼ 60K for YBaCo{sub 3}FeO{sub 7} but not a long-range antiferromagnetic order. We compare our results with AC and DC susceptibility measurements and discuss a possible competition between a spin glass-like state due to intrinsic structural disorder and a spin liquid state arising from strong magnetic frustration in this materials.

  11. Strong-Weak Coupling Self-Duality and Dimensional Reduction in the Two-Dimensional p+ip Superconducting Arrays and Frustrated Magnets

    Science.gov (United States)

    Xu, Cenke; Moore, Joel

    2005-03-01

    We discuss models of superconducting arrays and frustrated magnets in two dimensions which show quantum phase transitions and self-dualities that are characteristic of one-dimensional problems. The first part of the talk explains how the geometric dependence of Josephson tunneling in time-reversal-breaking superconductors leads naturally to effective Hamiltonians containing four-point interactions rather than two-point interactions. This work was motivated by the observation of possible T-breaking p+ip order in Sr2RuO4, but similar four-point interactions appear in the 1/S expansion of certain standard models of frustrated magnetism. We show that many models on the square lattice with four-point interactions contain infinitely many gauge-like symmetries, and generalize the self-duality of the quantum Ising model in one dimension to related models in all higher dimensions. The existence of these nonperturbative self-dualities gives exact information on the phase diagram of the superconducting array models and on the phase transition between globally T-ordered and globally T-breaking states.

  12. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  13. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  14. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  15. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  16. Active elimination of radio frequency interference for improved signal-to-noise ratio for in-situ NMR experiments in strong magnetic field gradients

    Science.gov (United States)

    Ibrahim, M.; Pardi, C. I.; Brown, T. W. C.; McDonald, P. J.

    2018-02-01

    Improvement in the signal-to-noise ratio of Nuclear Magnetic Resonance (NMR) systems may be achieved either by increasing the signal amplitude or by decreasing the noise. The noise has multiple origins - not all of which are strictly "noise": incoherent thermal noise originating in the probe and pre-amplifiers, probe ring down or acoustic noise and coherent externally broadcast radio frequency transmissions. The last cannot always be shielded in open access experiments. In this paper, we show that pulsed, low radio-frequency data communications are a significant source of broadcast interference. We explore two signal processing methods of de-noising short T2∗ NMR experiments corrupted by these communications: Linear Predictive Coding (LPC) and the Discrete Wavelet Transform (DWT). Results are shown for numerical simulations and experiments conducted under controlled conditions with pseudo radio frequency interference. We show that both the LPC and DWT methods have merit.

  17. Effects of Cr Substitution on Negative Thermal Expansion and Magnetic Properties of Antiperovskite Ga1−xCrxN0.83Mn3 Compounds

    Science.gov (United States)

    Guo, Xinge; Tong, Peng; Lin, Jianchao; Yang, Cheng; Zhang, Kui; Lin, Shuai; Song, Wenhai; Sun, Yuping

    2018-01-01

    Negative thermal expansion (NTE) and magnetic properties were investigated for antiperovskite Ga1−xCrxN0.83Mn3 compounds. As x increases, the temperature span (ΔT) of NTE related with Γ5g antiferromagnetic (AFM) order is expanded and shifted to lower temperatures. At x = 0.1, NTE happens between 256 and 318 K (ΔT = 62 K) with an average linear coefficient of thermal expansion, αL = −46 ppm/K. The ΔT is expanded to 81 K (151–232 K) in x = 0.2 with αL = −22.6 ppm/K. Finally, NTE is no longer visible for x ≥ 0.3. Ferromagnetic order is introduced by Cr doping and continuously strengthened with increasing x, which may impede the AFM ordering and thus account for the broadening of NTE temperature window. Moreover, our specific heat measurement suggests the electronic density of states at the Fermi level is enhanced upon Cr doping, which favors the FM order rather than the AFM one. PMID:29619367

  18. Effects of Cr Substitution on Negative Thermal Expansion and Magnetic Properties of Antiperovskite Ga1-x Cr x N0.83Mn3 Compounds.

    Science.gov (United States)

    Guo, Xinge; Tong, Peng; Lin, Jianchao; Yang, Cheng; Zhang, Kui; Lin, Shuai; Song, Wenhai; Sun, Yuping

    2018-01-01

    Negative thermal expansion (NTE) and magnetic properties were investigated for antiperovskite Ga 1- x Cr x N 0.83 Mn 3 compounds. As x increases, the temperature span (Δ T ) of NTE related with Γ 5g antiferromagnetic (AFM) order is expanded and shifted to lower temperatures. At x = 0.1, NTE happens between 256 and 318 K (Δ T = 62 K) with an average linear coefficient of thermal expansion, α L = -46 ppm/K. The Δ T is expanded to 81 K (151-232 K) in x = 0.2 with α L = -22.6 ppm/K. Finally, NTE is no longer visible for x ≥ 0.3. Ferromagnetic order is introduced by Cr doping and continuously strengthened with increasing x , which may impede the AFM ordering and thus account for the broadening of NTE temperature window. Moreover, our specific heat measurement suggests the electronic density of states at the Fermi level is enhanced upon Cr doping, which favors the FM order rather than the AFM one.

  19. Pressure drop and heat transfer of a mercury single-phase flow and an air-mercury two-phase flow in a helical tube under a strong magnetic field

    International Nuclear Information System (INIS)

    Takahashi, Minoru; Momozaki, Yoichi

    2000-01-01

    For the reduction of a large magneto-hydrodynamic (MHD) pressure drop of a liquid metal single-phase flow, a liquid metal two-phase flow cooling system has been proposed. As a fundamental study, MHD pressure drops and heat transfer characteristics of a mercury single-phase flow and an air-mercury two-phase flow were experimentally investigated. A strong transverse magnetic field relevant to the fusion reactor conditions was applied to the mercury single-phase flow and the air-mercury two-phase flow in a helically coiled tube that was inserted in the vertical bore of a solenoidal superconducting magnet. It was found that MHD pressure drops of a mercury single-phase flow in the helically coiled tube were nearly equal to those in a straight tube. The Nusselt number at an outside wall was higher than that at an inside wall both in the mercury single-phase flow in the absence and presence of a magnetic field. The Nusselt number of the mercury single-phase flow decreased, increased and again decreased with an increase in the magnetic flux density. MHD pressure drops did not decrease appreciably by injecting air into a mercury flow and changing the mercury flow into the air-mercury two-phase flow. Remarkable heat transfer enhancement did not appear by the air injection. The injection of air into the mercury flow enhanced heat transfer in the ranges of high mercury flow rate and low magnetic flux density, possibly due to the agitation effect of air bubbles. The air injection deteriorated heat transfer in the range of low mercury flow rates possibly because of the occupation of air near heating wall

  20. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  1. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  2. Lactic Acid Bacteria Inducing a Weak Interleukin-12 and Tumor Necrosis Alpha Response in Human Dendritic Cells Inhibit Strongly Stimulating Lactic Acid Bacteria but Act Synergistically with Gram-Negative Bacteria

    DEFF Research Database (Denmark)

    Zeuthen, Louise Hjerrild; Christensen, Hanne Risager; Frøkiær, Hanne

    2006-01-01

    The development and maintenance of immune homeostasis indispensably depend on signals from the gut flora. Lactic acid bacteria (LAB), which are gram-positive (G+) organisms, are plausible significant players and have received much attention. Gram-negative (G-) commensals, such as members...

  3. Crystal Growth of High-Quality Protein Crystals under the Presence of an Alternant Electric Field in Pulse-Wave Mode, and a Strong Magnetic Field with Radio Frequency Pulses Characterized by X-ray Diffraction

    Directory of Open Access Journals (Sweden)

    Adela Rodríguez-Romero

    2017-06-01

    Full Text Available The first part of this research was devoted to investigating the effect of alternate current (AC using four different types of wave modes (pulse-wave at 2 Hz on the crystal growth of lysozyme in solution. The best results, in terms of size and crystal quality, were obtained when protein crystals were grown under the influence of electric fields in a very specific wave mode (“breathing” wave, giving the highest resolution up to 1.34 Å in X-ray diffraction analysis compared with controls and with those crystals grown in gel. In the second part, we evaluated the effect of a strong magnetic field of 16.5 Tesla combined with radiofrequency pulses of 0.43 μs on the crystal growth in gels of tetragonal hen egg white (HEW lysozyme. The lysozyme crystals grown, both in solution applying breathing-wave and in gel under the influence of this strong magnetic field with pulses of radio frequencies, produced the larger-in-size crystals and the highest resolution structures. Data processing and refinement statistics are very good in terms of the resolution, mosaicity and Wilson B factor obtained for each crystal. Besides, electron density maps show well-defined and distinctly separated atoms at several selected tryptophan residues for the crystal grown using the “breathing wave pulses”.

  4. Thermodynamic properties of Ba2CoSi2O6Cl2 in a strong magnetic field: Realization of flat-band physics in a highly frustrated quantum magnet

    Science.gov (United States)

    Richter, Johannes; Krupnitska, Olesia; Baliha, Vasyl; Krokhmalskii, Taras; Derzhko, Oleg

    2018-01-01

    The search for flat-band solid-state realizations is a crucial issue to verify or to challenge theoretical predictions for quantum many-body flat-band systems. For frustrated quantum magnets flat bands lead to various unconventional properties related to the existence of localized many-magnon states. The recently synthesized magnetic compound Ba2CoSi2O6Cl2 seems to be an almost perfect candidate to observe these features in experiments. We develop a theory for Ba2CoSi2O6Cl2 by adapting the localized-magnon concept to this compound. We first show that our theory describes the known experimental facts and then we propose new experimental studies to detect a field-driven phase transition related to a Wigner-crystal-like ordering of localized magnons at low temperatures.

  5. MAGNET

    CERN Multimedia

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  6. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  7. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  8. Multicentre evaluation of targeted and systematic biopsies using magnetic resonance and ultrasound image-fusion guided transperineal prostate biopsy in patients with a previous negative biopsy.

    Science.gov (United States)

    Hansen, Nienke L; Kesch, Claudia; Barrett, Tristan; Koo, Brendan; Radtke, Jan P; Bonekamp, David; Schlemmer, Heinz-Peter; Warren, Anne Y; Wieczorek, Kathrin; Hohenfellner, Markus; Kastner, Christof; Hadaschik, Boris

    2017-11-01

    To evaluate the detection rates of targeted and systematic biopsies in magnetic resonance imaging (MRI) and ultrasound (US) image-fusion transperineal prostate biopsy for patients with previous benign transrectal biopsies in two high-volume centres. A two centre prospective outcome study of 487 patients with previous benign biopsies that underwent transperineal MRI/US fusion-guided targeted and systematic saturation biopsy from 2012 to 2015. Multiparametric MRI (mpMRI) was reported according to Prostate Imaging Reporting and Data System (PI-RADS) Version 1. Detection of Gleason score 7-10 prostate cancer on biopsy was the primary outcome. Positive (PPV) and negative (NPV) predictive values including 95% confidence intervals (95% CIs) were calculated. Detection rates of targeted and systematic biopsies were compared using McNemar's test. The median (interquartile range) PSA level was 9.0 (6.7-13.4) ng/mL. PI-RADS 3-5 mpMRI lesions were reported in 343 (70%) patients and Gleason score 7-10 prostate cancer was detected in 149 (31%). The PPV (95% CI) for detecting Gleason score 7-10 prostate cancer was 0.20 (±0.07) for PI-RADS 3, 0.32 (±0.09) for PI-RADS 4, and 0.70 (±0.08) for PI-RADS 5. The NPV (95% CI) of PI-RADS 1-2 was 0.92 (±0.04) for Gleason score 7-10 and 0.99 (±0.02) for Gleason score ≥4 + 3 cancer. Systematic biopsies alone found 125/138 (91%) Gleason score 7-10 cancers. In patients with suspicious lesions (PI-RADS 4-5) on mpMRI, systematic biopsies would not have detected 12/113 significant prostate cancers (11%), while targeted biopsies alone would have failed to diagnose 10/113 (9%). In equivocal lesions (PI-RADS 3), targeted biopsy alone would not have diagnosed 14/25 (56%) of Gleason score 7-10 cancers, whereas systematic biopsies alone would have missed 1/25 (4%). Combination with PSA density improved the area under the curve of PI-RADS from 0.822 to 0.846. In patients with high probability mpMRI lesions, the highest detection rates of Gleason

  9. cis-Thioindigo (TI) - a new ligand with accessible radical anion and dianion states. Strong magnetic coupling in the {[TI-(μ2-O),(μ-O)]Cp*Cr}2 dimers.

    Science.gov (United States)

    Konarev, Dmitri V; Khasanov, Salavat S; Shestakov, Alexander F; Fatalov, Alexey M; Batov, Mikhail S; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N

    2017-10-24

    Reaction of decamethylchromocene (Cp* 2 Cr) with thioindigo (TI) yields a coordination complex {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 ·C 6 H 14 (1) in which one Cp* ligand in Cp* 2 Cr is substituted by TI. TI adopts cis-conformation in 1 allowing the coordination of both carbonyl groups to chromium. Additionally, one oxygen atom of TI becomes a μ 2 -bridge for two chromium atoms to form {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 dimers with a CrCr distance of 3.12 Å. According to magnetic data, diamagnetic TI 2- dianions and two Cr 3+ atoms with a high S = 3/2 spin state are present in a dimer allowing strong antiferromagnetic coupling between two Cr 3+ spins with an exchange interaction of -35.4 K and the decrease of molar magnetic susceptibility below 140 K. Paramagnetic TI˙ - radical anions with the S = 1/2 spin state have also been obtained and studied in crystalline {cryptand[2,2,2](Na + )}(TI˙ - ) (2) salt showing that both radical anion and dianion states are accessible for TI.

  10. When negation is not negation

    OpenAIRE

    Milicevic, Nataša

    2008-01-01

    In this paper I will discuss the formation of different types of yes/no questions in Serbian (examples in (1)), focusing on the syntactically and semantically puzzling example (1d), which involves the negative auxiliary inversion. Although there is a negative marker on the fronted auxiliary, the construction does not involve sentential negation. This coincides with the fact that the negative quantifying NPIs cannot be licensed. The question formation and sentential negation have similar synta...

  11. Positive and negative exchange bias effects from magnetization reversal in Ho{sup 3+} doped YFe{sub 0.5}Cr{sub 0.5}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.R., E-mail: shiliran1127@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Wei, C.X.; Wang, Z.; Ju, L.; Xu, T.S.; Li, T.X.; Yan, X.W. [College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Xia, Z.C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2017-07-01

    Highlights: • The dual magnetization reversal is observed in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. • The EB field transforms from negative to positive and then to negative. • A large exchange bias effect induced by Ho{sup 3+} doping is obtained in Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. - Abstract: The polycrystalline ceramics of Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3} (x = 0, 0.05 and 0.1) are synthesized by a sol-gel method. The magnetization reversal and exchange bias effect are investigated in single phase bulk Y{sub 1−x}Ho{sub x}Fe{sub 0.5}Cr{sub 0.5}O{sub 3}. Magnetic Ho{sup 3+} ion as a dopant is introduced into the system to confirm the influence of A-site ion on the magnetic interactions. The dual reversal of exchange bias field for x = 0.05 is observed, and its characteristic temperatures are corresponding to the compensation temperatures of magnetization reversal. The exchange bias field of x = 0.1 is found to be ∼10.03 kOe at 4 K, revealing a large value compared with that of x = 0. A schematic diagram based on the competition between the single ion anisotropy and Dzyaloshinsky-Moriya interaction, and the antiparallel coupling between the Ho{sup 3+} moments and the canted Cr{sup 3+}/Fe{sup 3+} moments, is used to understand the dual reversal phenomenon of magnetization and exchange bias effect.

  12. Superconducting Magnets

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    Starting from the beam requirements for accelerator magnets, we will outline the main issues and the physical limitations for producing strong and pure magnetic fields with superconductors. The seminar will mainly focus on the magnets for the accelerator, and give some hints on the magnets for the experiments. Prerequisite knowledge: Basic knowledge of Maxwell equations, and linear optics for particle accelerators (FODO cell, beta functions).

  13. Collapsed tetragonal phase as a strongly covalent and fully nonmagnetic state: Persistent magnetism with interlayer As-As bond formation in Rh-doped Ca0 .8Sr0 .2Fe2As2

    Science.gov (United States)

    Zhao, K.; Glasbrenner, J. K.; Gretarsson, H.; Schmitz, D.; Bednarcik, J.; Etter, M.; Sun, J. P.; Manna, R. S.; Al-Zein, A.; Lafuerza, S.; Scherer, W.; Cheng, J. G.; Gegenwart, P.

    2018-02-01

    A well-known feature of the CaFe2As2 -based superconductors is the pressure-induced collapsed tetragonal phase that is commonly ascribed to the formation of an interlayer As-As bond. Using detailed x-ray scattering and spectroscopy, we find that Rh-doped Ca0.8Sr0.2Fe2As2 does not undergo a first-order phase transition and that local Fe moments persist despite the formation of interlayer As-As bonds. Our density functional theory calculations reveal that the Fe-As bond geometry is critical for stabilizing magnetism and the pressure-induced drop in the c lattice parameter observed in pure CaFe2As2 is mostly due to a constriction within the FeAs planes. The collapsed tetragonal phase emerges when covalent bonding of strongly hybridized Fe 3 d and As 4 p states completely wins out over their exchange splitting. Thus the collapsed tetragonal phase is properly understood as a strong covalent phase that is fully nonmagnetic with the As-As bond forming as a by-product.

  14. Cr doping induced negative transverse magnetoresistance in C d3A s2 thin films

    Science.gov (United States)

    Liu, Yanwen; Tiwari, Rajarshi; Narayan, Awadhesh; Jin, Zhao; Yuan, Xiang; Zhang, Cheng; Chen, Feng; Li, Liang; Xia, Zhengcai; Sanvito, Stefano; Zhou, Peng; Xiu, Faxian

    2018-02-01

    The magnetoresistance of a material conveys various dynamic information about charge and spin carriers, inspiring both fundamental studies in physics and practical applications such as magnetic sensors, data storage, and spintronic devices. Magnetic impurities play a crucial role in the magnetoresistance as they induce exotic states of matter such as the quantum anomalous Hall effect in topological insulators and tunable ferromagnetic phases in dilute magnetic semiconductors. However, magnetically doped topological Dirac semimetals are hitherto lacking. Here, we report a systematic study of Cr-doped C d3A s2 thin films grown by molecular-beam epitaxy. With the Cr doping, C d3A s2 thin films exhibit unexpected negative transverse magnetoresistance and strong quantum oscillations, bearing a trivial Berry's phase and an enhanced effective mass. More importantly, with ionic gating the magnetoresistance of Cr-doped C d3A s2 thin films can be drastically tuned from negative to positive, demonstrating the strong correlation between electrons and the localized spins of the Cr impurities, which we interpret through the formation of magnetic polarons. Such a negative magnetoresistance under perpendicular magnetic field and its gate tunability have not been observed previously in the Dirac semimetal C d3A s2 . The Cr-induced topological phase transition and the formation of magnetic polarons in C d3A s2 provide insights into the magnetic interaction in Dirac semimetals as well as their potential applications in spintronics.

  15. A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Hasan, E-mail: samarhass@yahoo.com [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Rahman, Mohammad Mostafizar; Ali, Mohammad Azgar [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Minami, Hideto [Graduate School of Engineering, Kobe University, Kobe 657-8501 (Japan); Tauer, Klaus [Max Planck Institute of Colloid and Interfaces, Am Mühlenberg, 14476 Golm (Germany); Gafur, Mohammad Abdul [Pilot Plant and Process Development Centre, BCSIR, Dhaka 1205 (Bangladesh); Rahman, Mohammad Mahbubor [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh)

    2016-08-15

    A combination of maghemite polypyrrole (PPy/γ-Fe{sub 2}O{sub 3}) and stimuli-responsive properties in the same hydrogel microspheres is expected to enhance their application potential in various fields such as tissue engineering, regenerative medicine, biosensors, biomedical applications and removal of heavy metals from waste water, catalysis etc. In this investigation a simple two step process is used to prepare conductive stimuli-responsive polypyrrole (PPy) composite hydrogel particles with strong magnetic properties. Poly(styrene-methacrylic acid-N-isopropylacrylamide-polyethelene glycol methacrylate) or P(S-NIPAM-MAA-PEGMA) hydrogel seed particles are first prepared by soap-free precipitation copolymerization. The copolymer hydrogel particles exhibited both temperature- and pH-responsive volume phase transition. Conductive P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles are then prepared by seeded chemical oxidative polymerization of pyrrole in the presence of P(S-NIPAM-MAA-PEGMA) hydrogel seed particles using FeCl{sub 3} as a oxidant and p-toluene sulfonic acid ( p-TSA) as a dopant. In the reaction system FeCl{sub 3} functioned as a source of Fe(III) for the formation of γ-Fe{sub 2}O{sub 3}. This reaction also requires the initial presence of Fe(II) provided by the addition of FeCl{sub 2}. The size and size distribution, surface structure, and morphology of the prepared conductive composite hydrogel particles are confirmed by FTIR, electron micrographs, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV–visible spectroscopy. The performance of nanocomposite hydrogel particles has been evaluated for the removal of hexavalent chromium (Cr) ions from water. - Highlights: • P(S-NIPAM-MAA-PEGMA) hydrogel particles were prepared. • P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles were prepared. • Oxidative polymerization of pyrrole and precipitation of γ-Fe{sub 2}O{sub 3

  16. Negative ... concord?

    NARCIS (Netherlands)

    Giannakidou, A

    The main claim of this paper is that a general theory of negative concord (NC) should allow for the possibility of NC involving scoping of a universal quantifier above negation. I propose that Greek NC instantiates this option. Greek n-words will be analyzed as polarity sensitive universal

  17. Isotropic Single Negative Metamaterials

    Directory of Open Access Journals (Sweden)

    P. Protiva

    2008-09-01

    Full Text Available This paper presents the application of simple, and therefore cheap, planar resonators for building 3D isotropic metamaterials. These resonators are: a broadside-coupled split ring resonator with a magnetic response providing negative permeability; an electric dipole terminated by a loop inductor together with a double H-shaped resonator with an electric response providing negative permittivity. Two kinds of 3D isotropic single negative metamaterials are reported. The first material consists of unit cells in the form of a cube bearing on its faces six equal planar resonators with tetrahedral symmetry. In the second material, the planar resonators boxed into spherical plastic shells and randomly distributed in a hosting material compose a real 3D volumetric metamaterial with an isotropic response. In both cases the metamaterial shows negative permittivity or permeability, according to the type of resonators that are used. The experiments prove the isotropic behavior of the cells and of the metamaterial specimens.

  18. Cardiac magnetic resonance imaging-indeterminate/negative cardiac sarcoidosis revealed by 18F-fluorodeoxyglucose-positron emission tomography: two case reports and a review of the literature

    Directory of Open Access Journals (Sweden)

    S. C. Sasson

    2017-10-01

    Full Text Available Abstract Background Sarcoidosis is an inflammatory disorder of immune dysregulation characterized by non-caseating granulomas that can affect any organ. Cardiac sarcoidosis is an under-recognized entity that has a heterogeneous presentation and may occur independently or with any severity of systemic disease. Diagnosing cardiac sarcoidosis remains problematic with endomyocardial biopsies associated with a high risk of complications. Several diagnostic algorithms are currently available that rely on histopathology or clinical and radiological measures. The dominant mode of diagnostic imaging to date for cardiac sarcoidosis has been cardiac magnetic resonance imaging with gadolinium enhancement. Case presentations We report the cases of two adult patients: case 1, a 50-year-old white man who presented with severe congestive cardiac failure; and case 2, a 37-year-old white woman who presented with complete heart block. Both patients had a background of untreated pulmonary sarcoidosis. Cardiac magnetic resonance imaging did not show evidence of sarcoidosis in either patient and both proceeded to 18F-fluorodeoxyglucose-positron emission tomography scans that were highly suggestive of cardiac sarcoidosis. Both patients were systemically immunosuppressed with orally administered prednisone and methotrexate and had subsequent improvement by clinical and nuclear medicine imaging measures. Conclusions Current consensus guidelines recommend all patients with sarcoidosis undergo screening for occult cardiac disease, with thorough history and examination, electrocardiogram, and transthoracic echocardiogram. If any abnormalities are detected, advanced cardiac imaging should follow. While cardiac magnetic resonance imaging identifies the majority of cardiac sarcoidosis, early disease may not be detected. These cases demonstrate 18F-fluorodeoxyglucose-positron emission tomography is warranted following an indeterminate or normal cardiac magnetic resonance

  19. Very strong negative trends in laminae in ozone profiles

    Czech Academy of Sciences Publication Activity Database

    Laštovička, Jan

    2002-01-01

    Roč. 27, - (2002), s. 477-483 ISSN 1474-7065 R&D Projects: GA AV ČR IAA3042101 Institutional research plan: CEZ:AV0Z3042911 Keywords : laminae profile of ozone * long-term trends Subject RIV: DG - Athmosphere Sciences, Meteorology

  20. Reaction of tin(iv) phthalocyanine dichloride with decamethylmetallocenes (M = CrII and CoII). Strong magnetic coupling of spins in (Cp*2Co+){SnIVCl2(Pc˙3-)}˙-·2C6H4Cl2.

    Science.gov (United States)

    Konarev, Dmitri V; Troyanov, Sergey I; Shestakov, Alexander F; Yudanova, Evgeniya I; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N

    2018-01-23

    The reaction of tin(iv) phthalocyanine dichloride {Sn IV Cl 2 (Pc 2- )} with decamethylmetallocenes (Cp* 2 M, M = Co, Cr) has been studied. Decamethylcobaltocene reduces Sn IV Cl 2 (Pc 2- ) to form the (Cp* 2 Co + ){Sn IV Cl 2 (Pc˙ 3- )}˙ - ·2C 6 H 4 Cl 2 (1) complex. The negative charge of {Sn IV Cl 2 (Pc˙ 3- )}˙ - is delocalized over the Pc macrocycle providing the alternation of the C-N(imine) bonds, the appearance of new bands in the NIR range and a strong blue shift of both the Soret and Q-bands in the spectrum of 1. The magnetic moment of 1 is equal to 1.68μ B at 300 K, indicating the contribution of one S = 1/2 spin of the Pc˙ 3- macrocycles. These macrocycles form closely packed double stacks in 1 with effective π-π interactions providing strong antiferromagnetic coupling of spins at a Weiss temperature of -80 K. Decamethylchromocene initially also reduces Sn IV Cl 2 (Pc 2- ) to form the [(Cp* 2 Cr + ){Sn VI Cl 2 (Pc˙ 3- )}˙ - complex but further reaction between the ions is observed. This reaction is accompanied by the substitution of one Cp* ligand of Cp* 2 Cr by chloride anions originating from {Sn IV Cl 2 (Pc˙ 3- )}˙ - to form the complex {(Cp*CrCl 2 )(Sn IV (μ-Cl)(Pc 2- ))}·C 6 H 4 Cl 2 (2) in which the (Cp*CrCl 2 ) and {Sn IV (Pc 2- )} species are bonded through the μ-bridged Cl - anion. According to the DFT calculations, this reaction proceeds via an intermediate [(Cp* 2 CrCl)(SnClPc)] complex.

  1. Negative Ion Density Fronts

    International Nuclear Information System (INIS)

    Igor Kaganovich

    2000-01-01

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas

  2. Magnetic resonance studies of mixed chalcospinel CuCr2SxSe4-x (x = 0; 2) and CoxCu1-xCr2S4 (x = 0.1; 0.2) nanocrystals with strong interparticle interactions

    Science.gov (United States)

    Pankrats, A. I.; Vorotynov, A. M.; Tugarinov, V. I.; Zharkov, S. M.; Zeer, G. M.; Ramasamy, K.; Gupta, A.

    2018-04-01

    Magnetic resonance characteristics of mixed chalcospinel nanocrystals CuCr2SxSe4-x (x = 0 and 2) and CoxCu1-xCr2S4 (x = 0.1 and 0.2) have been investigated. It has been established based on TEM, SEM and resonance data that all the samples contain both blocks with sizes from 1 to 50 m of compacted nanosized crystallites and individual nanoparticles with sizes from 10 to 30 nm. The studies provide evidence of strong interparticle interaction in all the samples leading to high values of the blocking temperature. Magnetic dipolar field arise in the boundary regions of interacting adjacent nanocrystals below the blocking temperature. This results in inhomogeneous broadening of the magnetic resonance spectrum along with appearance of additional absorption lines. With increase in magnetic anisotropy at low temperatures, a shift of the resonance field along with line broadening are observed for all the studied compounds due to freezing of the moments in the nanoparticles, both in the individual and compacted ones. A gapped characteristic of the resonance spectrum is established below the freezing temperature Tfr, with the energy gap defined by the averaged magnetic anisotropy . Anionic substitution of sulfur by selenium results in a decrease in the magnetic anisotropy. In contrast, cationic substitution of copper by cobalt increases the magnetic anisotropy due to a strong contribution from the latter ion.

  3. Theoretical studies of strongly correlated fermions

    Energy Technology Data Exchange (ETDEWEB)

    Logan, D. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Strongly correlated fermions are investigated. An understanding of strongly correlated fermions underpins a diverse range of phenomena such as metal-insulator transitions, high-temperature superconductivity, magnetic impurity problems and the properties of heavy-fermion systems, in all of which local moments play an important role. (author).

  4. Self-assembled magnetic filter for highly efficient immunomagnetic separation.

    Science.gov (United States)

    Issadore, David; Shao, Huilin; Chung, Jaehoon; Newton, Andita; Pittet, Mikael; Weissleder, Ralph; Lee, Hakho

    2011-01-07

    We have developed a compact and inexpensive microfluidic chip, the self-assembled magnetic filter, to efficiently remove magnetically tagged cells from suspension. The self-assembled magnetic filter consists of a microfluidic channel built directly above a self-assembled NdFeB magnet. Micrometre-sized grains of NdFeB assemble to form alternating magnetic dipoles, creating a magnetic field with a very strong magnitude B (from the material) and field gradient ▽B (from the configuration) in the microfluidic channel. The magnetic force imparted on magnetic beads is measured to be comparable to state-of-the-art microfabricated magnets, allowing for efficient separations to be performed in a compact, simple device. The efficiency of the magnetic filter is characterized by sorting non-magnetic (polystyrene) beads from magnetic beads (iron oxide). The filter enriches the population of non-magnetic beads to magnetic beads by a factor of >10(5) with a recovery rate of 90% at 1 mL h(-1). The utility of the magnetic filter is demonstrated with a microfluidic device that sorts tumor cells from leukocytes using negative immunomagnetic selection, and concentrates the tumor cells on an integrated membrane filter for optical detection.

  5. A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution

    Science.gov (United States)

    Ahmad, Hasan; Rahman, Mohammad Mostafizar; Ali, Mohammad Azgar; Minami, Hideto; Tauer, Klaus; Gafur, Mohammad Abdul; Rahman, Mohammad Mahbubor

    2016-08-01

    A combination of maghemite polypyrrole (PPy/γ-Fe2O3) and stimuli-responsive properties in the same hydrogel microspheres is expected to enhance their application potential in various fields such as tissue engineering, regenerative medicine, biosensors, biomedical applications and removal of heavy metals from waste water, catalysis etc. In this investigation a simple two step process is used to prepare conductive stimuli-responsive polypyrrole (PPy) composite hydrogel particles with strong magnetic properties. Poly(styrene-methacrylic acid-N-isopropylacrylamide-polyethelene glycol methacrylate) or P(S-NIPAM-MAA-PEGMA) hydrogel seed particles are first prepared by soap-free precipitation copolymerization. The copolymer hydrogel particles exhibited both temperature- and pH-responsive volume phase transition. Conductive P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe2O3 nanocomposite hydrogel particles are then prepared by seeded chemical oxidative polymerization of pyrrole in the presence of P(S-NIPAM-MAA-PEGMA) hydrogel seed particles using FeCl3 as a oxidant and p-toluene sulfonic acid (p-TSA) as a dopant. In the reaction system FeCl3 functioned as a source of Fe(III) for the formation of γ-Fe2O3. This reaction also requires the initial presence of Fe(II) provided by the addition of FeCl2. The size and size distribution, surface structure, and morphology of the prepared conductive composite hydrogel particles are confirmed by FTIR, electron micrographs, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV-visible spectroscopy. The performance of nanocomposite hydrogel particles has been evaluated for the removal of hexavalent chromium (Cr) ions from water.

  6. PREFACE: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Saxena, Siddharth S.; Littlewood, P. B.

    2012-07-01

    This special section is dedicated to the Strongly Correlated Electron Systems Conference (SCES) 2011, which was held from 29 August-3 September 2011, in Cambridge, UK. SCES'2011 is dedicated to 100 years of superconductivity and covers a range of topics in the area of strongly correlated systems. The correlated electronic and magnetic materials featured include f-electron based heavy fermion intermetallics and d-electron based transition metal compounds. The selected papers derived from invited presentations seek to deepen our understanding of the rich physical phenomena that arise from correlation effects. The focus is on quantum phase transitions, non-Fermi liquid phenomena, quantum magnetism, unconventional superconductivity and metal-insulator transitions. Both experimental and theoretical work is presented. Based on fundamental advances in the understanding of electronic materials, much of 20th century materials physics was driven by miniaturisation and integration in the electronics industry to the current generation of nanometre scale devices. The achievements of this industry have brought unprecedented advances to society and well-being, and no doubt there is much further to go—note that this progress is founded on investments and studies in the fundamentals of condensed matter physics from more than 50 years ago. Nevertheless, the defining challenges for the 21st century will lie in the discovery in science, and deployment through engineering, of technologies that can deliver the scale needed to have an impact on the sustainability agenda. Thus the big developments in nanotechnology may lie not in the pursuit of yet smaller transistors, but in the design of new structures that can revolutionise the performance of solar cells, batteries, fuel cells, light-weight structural materials, refrigeration, water purification, etc. The science presented in the papers of this special section also highlights the underlying interest in energy-dense materials, which

  7. Comparison of Superparamagnetic and Ultrasmall Superparamagnetic Iron Oxide Cell Labeling for Tracking Green Fluorescent Protein Gene Marker with Negative and Positive Contrast Magnetic Resonance Imaging

    OpenAIRE

    Zhang, Zhuoli; Dharmakumar, Rohan; Mascheri, Nicole; Fan, Zhaoyang; Wu, Shengyong; Li, Debiao

    2009-01-01

    The objectives of this study were to investigate the feasibility of imaging green fluorescent protein (GFP)-expressing cells labeled with iron oxide nanoparticles with the fast low-angle positive contrast steady-state free precession (FLAPS) method and to compare them with the traditional negative contrast technique. The GFP-R3230Ac cell line (GFP cell) was incubated for 24 hours using 20 μg Fe/mL concentration of superparamagnetic iron oxide (SPIO) and ultrasmall superparamagnetic iron oxide...

  8. Testing strong interaction theories

    International Nuclear Information System (INIS)

    Ellis, J.

    1979-01-01

    The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)

  9. Rydberg atoms in strong fields

    International Nuclear Information System (INIS)

    Kleppner, D.; Tsimmerman, M.

    1985-01-01

    Experimental and theoretical achievements in studying Rydberg atoms in external fields are considered. Only static (or quasistatic) fields and ''one-electron'' atoms, i.e. atoms that are well described by one-electron states, are discussed. Mainly behaviour of alkali metal atoms in electric field is considered. The state of theoretical investigations for hydrogen atom in magnetic field is described, but experimental data for atoms of alkali metals are presented as an illustration. Results of the latest experimental and theoretical investigations into the structure of Rydberg atoms in strong fields are presented

  10. Uso do contraste oral negativo em exames de colangiografia por ressonância magnética Use of oral negative contrast agent in magnetic resonance cholangiopancreatography examinations

    Directory of Open Access Journals (Sweden)

    Mário de Melo Galvão Filho

    2002-10-01

    Full Text Available OBJETIVO: Realizamos estudo prospectivo das vias biliares e pancreáticas através de colangiografia por ressonância magnética, com a utilização de meio de contraste oral negativo. Os nossos objetivos foram verificar se este novo meio de contraste melhora a visualização das vias biliar e pancreática, além de identificar a freqüência de efeitos colaterais ao contraste e sua aceitação pelo paciente. MATERIAL E MÉTODO: Quinze voluntários (oito homens e sete mulheres com idades variando entre 18 e 54 anos (média de 29 anos, sem queixas ou cirurgias abdominais, foram submetidos a colangiografia por ressonância magnética. Foram realizadas duas seqüências colangiográficas em apnéia, antes e cinco minutos após a ingestão de 300 ml de contraste oral negativo. Os exames foram realizados em equipamento operando a 1,0 T. RESULTADOS: Setenta e três por cento dos voluntários consideraram o gosto ruim ou muito ruim, sugerindo uma aceitação discutível; 27% dos voluntários apresentaram náuseas; 20%, cólicas; 14%, azia ou parestesia labial; e 7%, diarréia. A visualização da via biliar extra-hepática foi considerada melhor após o contraste oral negativo em 9/15 voluntários (60% e do ducto pancreático principal em todos os cinco em que havia interposição de alças. CONCLUSÃO: O contraste oral negativo melhora a visualização dos ductos hepatocolédoco e pancreático principal em exames de colangiografia por ressonância magnética, apesar da baixa aceitação e dos seus efeitos colaterais.OBJECTIVE: The aim of this prospective study was to investigate the feasibility of using a negative oral contrast agent to null the bowel signal during magnetic resonance cholangiopancreatography. MATERIAL AND METHOD: Fifteen healthy volunteers with no previous history of pancreaticobiliary disease or surgery were imaged with a single-shot fast spin-echo pulse sequence, using a magnetic resonance imaging system operating at 1.0 T. Data

  11. [Negative hallucination, self-onsciousness and ageing].

    Science.gov (United States)

    Hazif-Thomas, C; Stephan, F; Walter, M; Thomas, P

    2015-04-01

    Negative hallucinations are characterized by a defect in perception of an object or a person, or a denial of the existence of their perception. Negative hallucinations create blank spaces, due to both an impossible representation and an incapability of investment in reality. They have a close relationship with Cotard's syndrome, delusional theme of organ denial observed in melancholic syndromes in the elderly. Phenomenological approach. The phenomenology of negative hallucinations provides quite an amount of information on the origin of the psychotic symptoms when one is rather old. The connections between hallucinations, mood disorders and negative symptoms are often difficult to live with for the nearest and dearest. Negative hallucinations require a strict approach to identify their expression that is crucial because a wide heterogeneity exists within the pathological pictures, as in Cotard's syndrome. Although the negative hallucination has an anti traumatic function in elderly people fighting against mental pain, it still represents a deficiency in symbolization. The prevalence of this symptom is without doubt underestimated, although its presence often underlines thymic suffering that is more striking. These hallucinatory symptoms have an important impact on the patients' daily life, and they appear to be prisoners of a suffering, which cannot be revealed. We propose in this article to review the clinical symptoms of negative hallucinations in the elderly and the way to manage them. The medicinal approaches are not always effective. A greater place must be given to what is in connection with the body, aiming at a strong impact and thus to offer non-pharmacological approaches, such as somatic ones, which can be either invasive (electroconvulsive therapy) or not (transcranial magnetic stimulation). Copyright © 2014. Published by Elsevier Masson SAS.

  12. Negative snakes in JET: evidence for negative shear

    International Nuclear Information System (INIS)

    Gill, R.D.; Alper, B.; Edwards, A.W.

    1994-01-01

    The signature of the negative snakes from the soft X-ray cameras is very similar to the more usual snakes except that the localised region of the snake has, compared with its surroundings, decreased rather than increased emission. Circumstances where negative snakes have been seen are reviewed. The negative snake appears as a region of increased resistance and of increased impurity density. The relationship between the shear and the current perturbation is shown, and it seem probable that the magnetic shear is reversed at the point of the negative snake, i.e. that q is decreasing with radius. 6 refs., 6 figs

  13. Metal Artifact Reduction Magnetic Resonance Imaging Around Arthroplasty Implants: The Negative Effect of Long Echo Trains on the Implant-Related Artifact.

    Science.gov (United States)

    Kumar, Neil M; de Cesar Netto, Cesar; Schon, Lew C; Fritz, Jan

    2017-05-01

    Long echo train length (ETL) is an often recommended but unproven technique to decrease metal artifacts on magnetic resonance imaging (MRI) scans. Therefore, we quantitatively and qualitatively assessed the effects of ETL on metal artifact on MRI scans using a cobalt-chromium-containing arthroplasty implant system. Using a total ankle arthroplasty system implanted into a human cadaver ankle and a clinical 1.5 T MRI system, turbo spin echo (TSE) pulse sequences were acquired with ETL ranging from 3 to 23 and receiver bandwidth (BW) from 100 to 750 Hz/pixel, whereas effective echo time and spatial resolution were controlled. A compressed sensing slice encoding for metal artifact correction TSE prototype pulse sequence was used as reference standard. End points included the total implant-related artifact area and implant-related signal void areas. Two raters evaluated the overall image quality and preference across varying BW and ETL. Two-factor analysis of variance, Friedman test, Kruskal-Wallis test, and Pearson correlation were used. P values of less than 0.05 were considered statistically significant. The total implant-related artifact area ranged from 0.119 for compressed sensing slice encoding for metal artifact correction (BW, 600 Hz/pixel; ETL, 3) to 0.265 for TSE (BW, 100 Hz/pixel; ETL, 23). Longer ETL significantly increases the total implant-related artifact area (P = 0.0004), whereas it decreased with increasing BW (P train length, but reduced with higher BW (P trains fail to reduce implant-related metal artifacts, but in fact cause degradation of image quality around the implant with resultant larger appearing total metal artifacts.

  14. Suppressing drift chamber diffusion without magnetic field

    International Nuclear Information System (INIS)

    Martoff, C.J.; Snowden-Ifft, D.P.; Ohnuki, T.; Spooner, N.; Lehner, M.

    2000-01-01

    The spatial resolution in drift chamber detectors for ionizing radiation is limited by diffusion of the primary electrons. A strong magnetic field along the drift direction is often applied (Fancher et al., Nucl. Instr. and Meth. A 161 (1979) 383) because it suppresses the transverse diffusion, improving the resolution but at considerable increase in cost and complexity. Here we show that transverse track diffusion can be strongly suppressed without any magnetic field. This is achieved by using a gas additive which reversibly captures primary ionization electrons, forming negative ions. The ions drift with thermal energies even at very high drift fields and low pressures (E/P=28.5 V/cm torr), and the diffusion decreases with increasing drift field. Upon arrival at the avalanche region of the chamber the negative ions are efficiently stripped and ordinary avalanche gain is obtained. Using this technique, r.m.s. transverse diffusion less than 200 μm has been achieved over a 15 cm drift path at 40 torr with zero magnetic field. The method can provide high spatial resolution in detectors with long drift distances and zero magnetic field. Negative ion drift chambers would be particularly useful at low pressures and in situations such as space-based or underground experiments where detector size scaleability is important and cost, space, or power constraints preclude the use of a magnetic field

  15. Efficient spin-filtering, magnetoresistance and negative differential resistance effects of a one-dimensional single-molecule magnet Mn(dmit2-based device with graphene nanoribbon electrodes

    Directory of Open Access Journals (Sweden)

    N. Liu

    2017-12-01

    Full Text Available We present first-principle spin-dependent quantum transport calculations in a molecular device constructed by one single-molecule magnet Mn(dmit2 and two graphene nanoribbon electrodes. Our results show that the device could generate perfect spin-filtering performance in a certain bias range both in the parallel configuration (PC and the antiparallel configuration (APC. At the same time, a magnetoresistance effect, up to a high value of 103%, can be realized. Moreover, visible negative differential resistance phenomenon is obtained for the spin-up current of the PC. These results suggest that our one-dimensional molecular device is a promising candidate for multi-functional spintronics devices.

  16. Pulsed Neutron Scattering Studies of Strongly Fluctuating solids, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Collin Broholm

    2006-06-22

    The conventional description of a solid is based on a static atomic structure with small amplitude so-called harmonic fluctuations about it. This is a final technical report for a project that has explored materials where fluctuations are sufficiently strong to severely challenge this approach and lead to unexpected and potentially useful materials properties. Fluctuations are enhanced when a large number of configurations share the same energy. We used pulsed spallation source neutron scattering to obtain detailed microscopic information about structure and fluctuations in such materials. The results enhance our understanding of strongly fluctuating solids and their potential for technical applications. Because new materials require new experimental techniques, the project has also developed new techniques for probing strongly fluctuating solids. Examples of material that were studied are ZrW2O8 with large amplitude molecular motion that leads to negative thermal expansion, NiGa2S4 where competing interactions lead to an anomalous short range ordered magnet, Pr1- xBixRu2O7 where a partially filled electron shell (Pr) in a weakly disordered environment produces anomalous metallic properties, and TbMnO3 where competing interactions lead to a magneto-electric phase. The experiments on TbMnO3 exemplify the relationship between research funded by this project and future applications. Magneto-electric materials may produce a magnetic field when an electric field is applied or vise versa. Our experiments have clarified the reason why electric and magnetic polarization is coupled in TbMnO3. While this knowledge does not render TbMnO3 useful for applications it will focus the search for a practical room temperature magneto-electric for applications.

  17. Prostate-specific Antigen Parameters and Prostate Health Index Enhance Prostate Cancer Prediction With the In-bore 3-T Magnetic Resonance Imaging-guided Transrectal Targeted Prostate Biopsy After Negative 12-Core Biopsy.

    Science.gov (United States)

    Friedl, Alexander; Stangl, Kathrin; Bauer, Wilhelm; Kivaranovic, Danijel; Schneeweiss, Jenifer; Susani, Martin; Hruby, Stephan; Lusuardi, Lukas; Lomoschitz, Fritz; Eisenhuber-Stadler, Edith; Schima, Wolfgang; Brössner, Clemens

    2017-12-01

    To assess prostate cancer (PCa) detection and prediction by combining the in-bore magnetic resonance imaging-guided transrectal targeted prostate biopsy (MRGB) with prostate-specific antigen (PSA) parameters and the Prostate Health Index (PHI) in case of negative 12-core standard biopsy. A total of 112 men (2014-2016) underwent 3-T multiparametric magnetic resonance imaging and subsequent MRGB of Prostate Imaging-Reporting and Data System (PI-RADS) lesions 3-5. Ancillary PSA parameters (PSA ratio [%fPSA] and PSA density [PSAD]) and the PHI and PHI density (PHID) were recorded. With these parameters in combination with MRGB, PCa prediction was calculated. The most common lesions biopsied were PI-RADS 4 (66%), located in the peripheral zone (64%), in the middle (58%) and anterior (65%) sections of the prostate, and 13 mm (IQR 10-15) in size. PCa was found in 62 (55%) patients (28% Gleason score ≥7). PSAD (0.15 vs 0.21; P = .0051), %fPSA (16 vs 13; P = .0191), PHI (45 vs 69; P PI-RADS 3-5 lesions. By considering PHI and PHID, 82% and 62% of unnecessary biopsies could have been avoided, failing to detect 31% and 16% of cancers. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Development of a strong electromagnet wiggler

    International Nuclear Information System (INIS)

    Burns, M.J.; Deis, G.A.; Holmes, R.H.; Van Maren, R.D.; Halbach, K.

    1987-01-01

    The Strong Electromagnet (SEM) wiggler is a permanent magnet-assisted electromagnet under development at the Lawrence Livermore National Laboratory (LLNL) as part of the Induction Linac Free-Electron-Laser (IFEL) program. This concept uses permanent magnets within the wiggler to provide a reverse bias flux in the iron and thus delay the onset of magnetic saturation. The electromagnet coils determine the wiggler field and operate at low current densities by virtue of their placement away from the midplane. We describe here the design approach used and test data from a 7-period wiggler prototype that includes curved pole tips to provide wiggle-plane focusing. 7 refs

  19. Combining Prostate Health Index density, magnetic resonance imaging and prior negative biopsy status to improve the detection of clinically significant prostate cancer.

    Science.gov (United States)

    Druskin, Sasha C; Tosoian, Jeffrey J; Young, Allen; Collica, Sarah; Srivastava, Arnav; Ghabili, Kamyar; Macura, Katarzyna J; Carter, H Ballentine; Partin, Alan W; Sokoll, Lori J; Ross, Ashley E; Pavlovich, Christian P

    2017-12-12

    To determine the performance of Prostate Health Index (PHI) density (PHID) combined with MRI and prior negative biopsy (PNB) status for the diagnosis of clinically significant prostate cancer (PCa). Patients without a prior diagnosis of PCa, with elevated prostate-specific antigen and a normal digital rectal examination who underwent PHI testing prospectively prior to prostate biopsy were included in this study. PHID was calculated retrospectively using prostate volume derived from transrectal ultrasonography at biopsy. Univariable and multivariable logistic regression modelling, along with receiver-operating characteristic (ROC) curve analysis, was used to determine the ability of serum biomarkers to predict clinically significant PCa (defined as either grade group [GG] ≥2 disease or GG1 PCa detected in >2 cores or >50% of any one core) on biopsy. Age, PNB status and Prostate Imaging Reporting and Data System (PI-RADS) score were incorporated into the regression models. Of the 241 men who qualified for the study, 91 (37.8%) had clinically significant PCa on biopsy. The median (interquartile range) PHID was 0.74 (0.44-1.24); it was 1.18 (0.77-1.83) and 0.55 (0.38-0.89) in those with and without clinically significant PCa on biopsy, respectively (P PI-RADS score was complementary to PHID, with a PI-RADS score ≥3 or, if PI-RADS score ≤2, a PHID ≥0.44, detecting 100% of clinically significant disease. For that subgroup, of the biomarkers tested, PHID (AUC 0.90) demonstrated the highest discriminative ability for clinically significant disease on multivariable logistic regression incorporating age, PNB status and PI-RADS score. In this contemporary cohort of men undergoing prostate biopsy for the diagnosis of PCa, PHID outperformed PHI and other PSA derivatives in the diagnosis of clinically significant cancer. Incorporating age, PNB status and PI-RADS score led to even further gains in the diagnostic performance of PHID. Furthermore, PI-RADS score was found to

  20. CuFe2O4 magnetic nanocrystal clusters as a matrix for the analysis of small molecules by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Lin, Zian; Zheng, Jiangnan; Bian, Wei; Cai, Zongwei

    2015-08-07

    CuFe2O4 magnetic nanocrystal clusters (CuFe2O4 MNCs) were proposed as a new matrix for small molecule analysis by negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the first time. We demonstrated its advantages over conventional organic matrices in the detection of small molecules such as amino acids, peptides, nucleobases, fatty acids, and steroid hormones. A systematic comparison of CuFe2O4 MNCs with different ionization modes revealed that MS spectra obtained for the CuFe2O4 MNC matrix in the negative ion mode was only featured by deprotonated ion peaks with a free matrix background, which was different from the complicated alkali metal adducts produced in the positive ion mode. The developed method was found relatively tolerant to salt contamination and exhibited good reproducibility. A detection limit down to the subpicomolar level was achieved when testosterone was analyzed. In addition, by comparison of the MS spectra obtained from bare Fe3O4 and MFe2O4 MNC (M = Co, Ni, Cu, Zn) matrices, two main factors of MFe2O4 MNC matrices were revealed to play a vital role in assisting the negative ion desorption/ionization (D/I) process: doping transition metals into ferrite nanocrystals favoring laser absorption and energy transfer and a good match between the UV absorption of MFe2O4 MNCs and the excitation of nitrogen laser source facilitating LDI efficiency. This work creates a new branch of application for MFe2O4 MNCs and provides an alternative solution for small molecule analysis.

  1. Strongly enhanced vortex pinning from 4 to 77 K in magnetic fields up to 31 T in 15 mol.% Zr-added (Gd, Y)-Ba-Cu-O superconducting tapes

    OpenAIRE

    A. Xu; L. Delgado; N. Khatri; Y. Liu; V. Selvamanickam; D. Abraimov; J. Jaroszynski; F. Kametani; D. C. Larbalestier

    2014-01-01

    Applications of REBCO coated conductors are now being developed for a very wide range of temperatures and magnetic fields and it is not yet clear whether vortex pinning strategies aimed for high temperature, low field operation are equally valid at lower temperatures and higher fields. A detailed characterization of the superconducting properties of a 15 mol. % Zr-added REBCO thin film made by metal organic chemical vapor deposition, from 4.2 to 77 K under magnetic fields up to 31 T is presen...

  2. Strongly Correlated Topological Insulators

    Science.gov (United States)

    2016-02-03

    Strongly Correlated Topological Insulators In the past year, the grant was used for work in the field of topological phases, with emphasis on finding...surface of topological insulators. In the past 3 years, we have started a new direction, that of fractional topological insulators. These are materials...in which a topologically nontrivial quasi-flat band is fractionally filled and then subject to strong interactions. The views, opinions and/or

  3. Strong Cosmic Censorship

    Science.gov (United States)

    Isenberg, James

    2017-01-01

    The Hawking-Penrose theorems tell us that solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his `Strong Cosmic Censorship Conjecture`) that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that ``AVTD behavior'' (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying model versions of Strong Cosmic Censorship in that family. I discuss some of the history of Strong Cosmic Censorship, and then discuss what is known about AVTD behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss recent results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. I also comment on some of the recent work on ``Weak Null Singularities'', and how this relates to Strong Cosmic Censorship.

  4. Lunar magnetism

    Science.gov (United States)

    Hood, L. L.; Sonett, C. P.; Srnka, L. J.

    1984-01-01

    Aspects of lunar paleomagnetic and electromagnetic sounding results which appear inconsistent with the hypothesis that an ancient core dynamo was the dominant source of the observed crustal magnetism are discussed. Evidence is summarized involving a correlation between observed magnetic anomalies and ejecta blankets from impact events which indicates the possible importance of local mechanisms involving meteoroid impact processes in generating strong magnetic fields at the lunar surface. A reply is given to the latter argument which also presents recent evidence of a lunar iron core.

  5. EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Ronning, Filip; Batista, Cristian

    2011-03-01

    Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 2010—co-chaired by John Sarrao and Joe Thompson—followed the tradition of earlier conferences, in this century, hosted by Buzios (2008), Houston (2007), Vienna (2005), Karlsruhe (2004), Krakow (2002) and Ann Arbor (2001). Every three years since 1997, SCES has joined the International Conference on Magnetism (ICM), held in Recife (2000), Rome (2003), Kyoto (2006) and Karlsruhe (2009). Like its predecessors, SCES 2010 topics included strongly correlated f- and d-electron systems, heavy-fermion behaviors, quantum-phase transitions, non-Fermi liquid phenomena, unconventional superconductivity, and emergent states that arise from electronic correlations. Recent developments from studies of quantum magnetism and cold atoms complemented the traditional subjects and were included in SCES 2010. 2010 celebrated the 400th anniversary of Santa Fe as well as the birth of astronomy. So what's the connection to SCES? The Dutch invention of the first practical telescope and its use by Galileo in 1610 and subsequent years overturned dogma that the sun revolved about the earth. This revolutionary, and at the time heretical, conclusion required innovative combinations of new instrumentation, observation and mathematics. These same combinations are just as important 400 years later and are the foundation of scientific discoveries that were discussed

  6. Strong Arcwise Connectedness

    OpenAIRE

    Espinoza, Benjamin; Gartside, Paul; Kovan-Bakan, Merve; Mamatelashvili, Ana

    2012-01-01

    A space is `n-strong arc connected' (n-sac) if for any n points in the space there is an arc in the space visiting them in order. A space is omega-strong arc connected (omega-sac) if it is n-sac for all n. We study these properties in finite graphs, regular continua, and rational continua. There are no 4-sac graphs, but there are 3-sac graphs and graphs which are 2-sac but not 3-sac. For every n there is an n-sac regular continuum, but no regular continuum is omega-sac. There is an omega-sac ...

  7. Abortion: Strong's counterexamples fail

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2009-01-01

    This paper shows that the counterexamples proposed by Strong in 2008 in the Journal of Medical Ethics to Marquis's argument against abortion fail. Strong's basic idea is that there are cases--for example, terminally ill patients--where killing an adult human being is prima facie seriously morally......'s scenarios have some valuable future or admitted that killing them is not seriously morally wrong. Finally, if "valuable future" is interpreted as referring to objective standards, one ends up with implausible and unpalatable moral claims....

  8. A strong comeback

    International Nuclear Information System (INIS)

    Marier, D.

    1992-01-01

    This article presents the results of a financial rankings survey which show a strong economic activity in the independent energy industry. The topics of the article include advisor turnover, overseas banks, and the increase in public offerings. The article identifies the top project finance investors for new projects and restructurings and rankings for lenders

  9. Transport simulation of negative magnetic shear discharges

    International Nuclear Information System (INIS)

    St. John, H.; Taylor, T.S.; Lin-Liu, Y.R.; Turnbull, A.D.

    1994-10-01

    In the present work the authors present simulations which show that the hollow current profile can be maintained in quasi-steady state through a self-consistently determined combination of bootstrap current and neutral beam and rf current drive. Controllability of the q profile is demonstrated by eliminating low m/n mode number instabilities from these discharges by maintaining q > 1.5 at all times, starting from appropriate initial conditions. At moderately high β p , the bootstrap current can be a substantial fraction of the total current and the ability to maintain the proper total current density profile depends on the bootstrap current profile and the availability of suitable localized heating and current drive. In these simulations, they use electron cyclotron heating, ion cyclotron heating, and electron cyclotron and fast wave current drive. The ability to maintain the profiles is demonstrated using several energy transport models. Self-consistent transport simulations are used to model the SSC discharges using the ONETWO transport code coupled to rf heating and current drive packages FASTWAVE and TORAY. To accurately model inductive and driven current profile evolution, the additional source terms that arise in Faraday's law due to internal flux surface motion are included by coupling the transport calculations to a fixed boundary equilibrium code. To test the sensitivity of the results to the transport model used, they model DIII-D discharges using thermal conductivities consistent with improved confinement DIII-D discharges, and with the Rebut-Lallia-Watkins model of energy transport

  10. Assessment of free-hand transperineal targeted prostate biopsy using multiparametric magnetic resonance imaging-transrectal ultrasound fusion in Chinese men with prior negative biopsy and elevated prostate-specific antigen.

    Science.gov (United States)

    Lian, Huibo; Zhuang, Junlong; Wang, Wei; Zhang, Bing; Shi, Jiong; Li, Danyan; Fu, Yao; Jiang, Xuping; Zhou, Weimin; Guo, Hongqian

    2017-07-05

    To evaluate the role of free-hand transperineal targeted prostate biopsy using multiparametric magnetic resonance imaging-transrectal ultrasound (mpMRI-TRUS) fusion in Chinese men with repeated biopsy. A total of 101 consecutive patients suspicious of prostate cancer (PCa) at the mpMRI scan and with prior negative biopsy and elevated PSA values were prospectively recruited at two urological centers. Suspicious areas on mpMRI were defined and graded using PI-RADS score. Targeted biopsies (TB) were performed for each suspicious lesion and followed a 12-core systematic biopsy (SB). Results of biopsy pathology and whole-gland pathology at prostatectomy were analyzed and compared between TB and SB. The risk for biopsy positivity was assessed by univariate and multivariate logistic regression analysis. Fusion biopsy revealed PCa in 41 of 101 men (40.6%) and 25 (24.8%) were clinically significant. There was exact agreement between TB and SB in 74 (73.3%) men. TB diagnosed 36% more significant cancer than SB (22 vs 13 cases, P = 0.012). When TB were combined with SB, an additional 14 cases (34.1%) of mostly significant PCa (71.4%) were diagnosed (P = 0.036). TB had greater sensitivity and accuracy for significant cancer than SB in 26 men with whole-gland pathology after prostatectomy. PI-RADS score on mpMRI was the most powerful predictor of PCa and significant cancer. Free-hand transperineal TB guided with MRI-TRUS fusion imaging improves detection of clinical significant PCa in Chinese men with previously negative biopsy. PI-RADS score is a reliable predictor of PCa and significant cancer.

  11. Rare earth permanent magnet with easy magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A.S.; Camp, F.E. [YBM Magnex, Inc., Newtown, PA (United States)

    1998-07-01

    Rare earth permanent magnets have high energy products and coercivities, and thus the volume miniaturization of magnetic devices has been possible with improved magnetic performance. Although the high energy products of these rare earth permanent magnets provide substantial advantages for magnetic design and application, the strong magnetic force of the magnetized magnets makes assembly difficult. Therefore, a special device is needed to assemble the magnetized magnets. On the other hand, unmagnetized magnets are assembled and then they are magnetized. The assembled magnets are generally more difficult to magnetize than unassembled magnets because a much less effective magnetic field may be applied to them. This is particularly true for the rare earth permanent magnets because they usually need a much higher magnetic field to be fully magnetized than alnico or ferrite magnets. To obtain optimum magnetic properties, the required minimum magnetizing fields for SmCo{sub 5}, Sm{sub 2}TM{sub 17} and Nd{sub 2}Fe{sub 14}B magnets were reported as 25-30 kOe, 45-60 kOe and 25-30 kOe, respectively. If the required magnetizing field for full saturation could be lowered, the effective utilization of magnetic properties would be maximized and the magnetic design option could be expanded with reduced restrictions. To meet this demand, we have sought to lower the field required for full magnetic saturation, and found that an increase in Dy content in R-(Fe,Co,Cu)-B type magnets lowers the field required for full saturation as well as improves the temperature stability. By increasing the H{sub ci} with Dy addition from 14 kOe to 24 and 34 kOe, the field required for full magnetic saturation decreases from about 20 to 15 and 10 kOe, respectively. This dual benefit will open up new application areas with more freedom for magnet design options. The mechanism for the lower magnetizing fields will be discussed. (orig.)

  12. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  13. Plasmons in strong superconductors

    International Nuclear Information System (INIS)

    Baldo, M.; Ducoin, C.

    2011-01-01

    We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to or smaller than the pairing gap. As a prototype of these systems we consider the proton component of Neutron Star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random-Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation modes. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high-T c superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.

  14. Electromotive force in strongly compressible magnetohydrodynamic turbulence

    Science.gov (United States)

    Yokoi, N.

    2017-12-01

    Variable density fluid turbulence is ubiquitous in geo-fluids, not to mention in astrophysics. Depending on the source of density variation, variable density fluid turbulence may be divided into two categories: the weak compressible (entropy mode) turbulence for slow flow and the strong compressible (acoustic mode) turbulence for fast flow. In the strong compressible turbulence, the pressure fluctuation induces a strong density fluctuation ρ ', which is represented by the density variance ( denotes the ensemble average). The turbulent effect on the large-scale magnetic-field B induction is represented by the turbulent electromotive force (EMF) (u': velocity fluctuation, b': magnetic-field fluctuation). In the usual treatment in the dynamo theory, the expression for the EMF has been obtained in the framework of incompressible or weak compressible turbulence, where only the variation of the mean density , if any, is taken into account. We see from the equation of the density fluctuation ρ', the density variance is generated by the large mean density variation ∂ coupled with the turbulent mass flux . This means that in the region where the mean density steeply changes, the density variance effect becomes relevant for the magnetic field evolution. This situation is typically the case for phenomena associated with shocks and compositional discontinuities. With the aid of the analytical theory of inhomogeneous compressible magnetohydrodynamic (MHD) turbulence, the expression for the turbulent electromotive force is investigated. It is shown that, among others, an obliqueness (misalignment) between the mean density gradient ∂ and the mean magnetic field B may contribute to the EMF as ≈χ B×∂ with the turbulent transport coefficient χ proportional to the density variance (χ ). This density variance effect is expected to strongly affect the EMF near the interface, and changes the transport properties of turbulence. In the case of an interface under the MHD slow

  15. The Shape of Strongly Disturbed Dayside Magnetopause

    Directory of Open Access Journals (Sweden)

    Alexei V. Dmitriev Alla V. Suvorova

    2013-01-01

    Full Text Available During strong geomagnetic disturbances, the Earth¡¦s magnetosphere exhibits unusual and nonlinear interaction with the incident flow of magnetized solar wind plasma. Global Magneto-hydro-dynamic (MHD modeling of the magnetosphere predicts that the storm-time effects at the magnetopause result from the abnormal plasma transport and/or extremely strong field aligned currents. In-situ observations of the magnetospheric boundary, magnetopause, by Geosynchronous Operational Environmental Satellite (GOES allowed us to find experimentally such effects as a saturation of the dayside reconnection, unusual bluntness and prominent duskward skewing of the nose magnetopause. The saturation and duskward skewing were attributed to the storm-time magnetopause formation under strong southward interplanetary magnetic field (IMF. The unusual bluntness was observed during both high solar wind pressure and strong southward IMF. We suggest that these phenomena are caused by a substantial contribution of the cross-tail current magnetic field and the hot magnetospheric plasma from the asymmetrical ring current into the pressure balance at the dayside magnetopause.

  16. Topics in strong Langmuir turbulence

    International Nuclear Information System (INIS)

    Skoric, M.M.

    1981-01-01

    This thesis discusses certain aspects of the turbulence of a fully ionised non-isothermal plasma dominated by the Langmuir mode. Some of the basic properties of strongly turbulent plasmas are reviewed. In particular, interest is focused on the state of Langmuir turbulence, that is the turbulence of a simple externally unmagnetized plasma. The problem of the existence and dynamics of Langmuir collapse is discussed, often met as a non-linear stage of the modulational instability in the framework of the Zakharov equations (i.e. simple time-averaged dynamical equations). Possible macroscopic consequences of such dynamical turbulent models are investigated. In order to study highly non-linear collapse dynamics in its advanced stage, a set of generalized Zakharov equations are derived. Going beyond the original approximation, the author includes the effects of higher electron non-linearities and a breakdown of slow-timescale quasi-neutrality. He investigates how these corrections may influence the collapse stabilisation. Recently, it has been realised that the modulational instability in a Langmuir plasma will be accompanied by the collisionless-generation of a slow-timescale magnetic field. Accordingly, a novel physical situation has emerged which is investigated in detail. The stability of monochromatic Langmuir waves in a self-magnetized Langmuir plasma, is discussed, and the existence of a novel magneto-modulational instability shown. The wave collapse dynamics is investigated and a physical interpretation of the basic results is given. A problem of the transient analysis of an interaction of time-dependent electromagnetic pulses with linear cold plasma media is investigated. (Auth.)

  17. Strong-coupling approximations

    International Nuclear Information System (INIS)

    Abbott, R.B.

    1984-03-01

    Standard path-integral techniques such as instanton calculations give good answers for weak-coupling problems, but become unreliable for strong-coupling. Here we consider a method of replacing the original potential by a suitably chosen harmonic oscillator potential. Physically this is motivated by the fact that potential barriers below the level of the ground-state energy of a quantum-mechanical system have little effect. Numerically, results are good, both for quantum-mechanical problems and for massive phi 4 field theory in 1 + 1 dimensions. 9 references, 6 figures

  18. Strong interaction and QFD

    International Nuclear Information System (INIS)

    Ebata, T.

    1981-01-01

    With an assumed weak multiplet structure for bosonic hadrons, which is consistent with the ΔI = 1/2 rule, it is shown that the strong interaction effective hamiltonian is compatible with the weak SU(2) x U(1) gauge transformation. Especially the rho-meson transforms as a triplet under SU(2)sub(w), and this is the origin of the rho-photon analogy. It is also shown that the existence of the non-vanishing Cabibbo angle is a necessary condition for the absence of the exotic hadrons. (orig.)

  19. Negative Refractive Index in Artificial Metamaterials

    OpenAIRE

    Grigorenko, A. N.

    2006-01-01

    We discuss optical constants in artificial metamaterials showing negative magnetic permeability and electric permittivity. Using effective field theory, we calculate effective permeability of nanofabricated media composed of pairs of identical gold nano-pillars with magnetic response in the visible spectrum.

  20. Strong Coupling Holography

    CERN Document Server

    Dvali, Gia

    2009-01-01

    We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the ...