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Sample records for magnetic-field-induced quadrupolar ordering

  1. Magnetic field induced 1st order transitions: Recent studies, and some new concepts

    NASA Astrophysics Data System (ADS)

    Chaddah, P.

    2015-05-01

    Phase transitions are caused by varying temperature, or pressure, or magnetic field. The observation of 1st order magneto-structural transitions has created application possibilities based on magnetoresistance, magnetocaloric effect, magnetic shape memory effect, and magneto-dielectric effect. Magnetic field induced transitions, and phase coexistence of competing magnetic phases down to the lowest temperature, gained prominence over a decade ago with theoretical models suggesting that the ground state is not homogeneous. Researchers at Indore pushed an alternative view that this phase coexistence could be due to glasslike "kinetic arrest" of a disorder-broadened first-order magnetic transition between two states with long-range magnetic order, resulting in phase coexistence down to the lowest temperatures. The CHUF (cooling and heating in unequal field) protocol created at Indore allows the observation of `devitrification', followed by `melting'. I show examples of measurements establishing kinetic arrest in various materials, emphasizing that glasslike arrest of 1st order magnetic transitions may be as ubiquitous as glass formation following the arrest of 1st order structural transitions.

  2. Magnetic-field-induced orientational order in the isotropic phase of hard colloidal platelets

    SciTech Connect

    Beek, D. van der; Petukhov, A.V.; Vroege, G.J.; Lekkerkerker, H.N.W.; Davidson, P.; Ferre, J.; Jamet, J.P.; Wensink, H.H.; Bras, W.

    2006-04-15

    The magnetic-field-induced orientational order in the isotropic phase of colloidal gibbsite [Al(OH){sub 3}] platelets is studied by means of optical birefringence and small-angle x-ray scattering (SAXS) techniques. The suspensions display field-induced ordering at moderate field strengths (a few Tesla), which increases with increasing particle concentration. The gibbsite particles align their normals perpendicular to the magnetic field and hence possess a negative anisotropy of their diamagnetic susceptibility {delta}{chi}. The results can be described following a simple, Onsager-like approach. A simplified model is derived that allows one to obtain the orientational distribution function directly from the scattering data. However, it leads to an underestimate of the diamagnetic susceptibility anisotropy {delta}{chi}. This accounts for the difference between the {delta}{chi} values provided by the two experimental techniques (SAXS and magneto-optics). The order of magnitude {delta}{chi}{approx}10{sup -22} J/T{sup 2} lies in between that of goethite suspensions and that of suspensions of organic particles.

  3. Quadrupolar Spin Orders in FeSe

    NASA Astrophysics Data System (ADS)

    Wang, Zhentao; Nevidomskyy, Andriy

    Motivated by the absence of long-range magnetic order and the strong spin fluctuations observed in the Fe-based superconductor FeSe, we study spin-1 model on a square lattice up to next-nearest neighbor Heisenberg and biquadratic spin exchanges. The zero-temperature variational phase diagram gives the conventional antiferromagnetic order and also more exotic quadrupolar spin phases. These quadrupolar phases do not host long-range magnetic order and preserve time-reversal symmetry, but break the spin SU(2) symmetry. In particular, we observe a robust ferroquadrupolar order (FQ) in immediate proximity to the columnar AFM phase. We envision that FeSe may be positioned within the FQ phase close to the phase boundary. Using the flavor-wave technique, we calculate the structure factor inside the FQ phase and find a Goldstone mode emerging from Q = (0 , 0) , which however bears zero spectral weight at ω = 0 due to time reversal symmetry. At the same time, we observe strong spin fluctuations near (π , 0) / (0 , π) , which agrees with the recent neutron scattering experiments. Further, we calculate the higher order interactions between the (π , 0) and (0 , π) spin fluctuations inside the FQ phase, which may shed light on the C4 symmetry breaking in the nematic phase of FeSe.

  4. Magnetic field-induced switching of magnetic ordering in SrFeO3- δ

    NASA Astrophysics Data System (ADS)

    Mohan Radheep, D.; Shanmugapriya, K.; Palanivel, Balan; Murugan, Ramaswamy

    2016-08-01

    The oxygen-deficient strontium iron oxide SrFeO3- δ (SFO) exhibits richness in the phase diagram over a broad range of temperatures and for other external parameters. Room-temperature X-ray diffraction and Raman spectrum reveals that the structure of synthesized SFO system consists of two mixed phases, i.e., major orthorhombic and minor tetragonal phases. The low-temperature Raman and vibrating sample magnetometer measurements indicated a structural transition below 253 K. The magnetic property of the synthesized SFO for various external magnetic field (up to 5 T) reveals possible variation in oxygen stoichiometry. Also, the application of external H increases Neel transition temperature ( T N), suppresses the hysteresis width ( W H), and thus weakens the first-order nature of the transition. Our analysis revealed the vanishing of hysteresis and the first-order antiferromagnetic transition becomes a crossover above a critical magnetic field H CR ≈ 5 T. Possible switching of magnetic ordering and oxidation state observed in same system enhances interest in related compounds which may be used in magnetic sensors and other magnetic switching devices.

  5. Magnetic field induced third order susceptibility of third order harmonic generation in a ZnMgSe strained quantum well

    SciTech Connect

    Mark, J. Abraham Hudson Peter, A. John

    2014-04-24

    Third order susceptibility of third order harmonic generation is investigated in a Zn{sub 0.1}Mg{sub 0.9}Se/Zn{sub 0.8}Mg{sub 0.2}Se/Zn{sub 0.1}Mg{sub 0.9}Se quantum well in the presence of magnetic field strength. The confinement potential is considered as the addition of energy offsets of the conduction band (or valence band) and the strain-induced potential in our calculations. The material dependent effective mass is followed throughout the computation because it has a high influence on the electron energy levels in low dimensional semiconductor systems.

  6. Magnetic field induced dynamical chaos

    SciTech Connect

    Ray, Somrita; Baura, Alendu; Bag, Bidhan Chandra

    2013-12-15

    In this article, we have studied the dynamics of a particle having charge in the presence of a magnetic field. The motion of the particle is confined in the x–y plane under a two dimensional nonlinear potential. We have shown that constant magnetic field induced dynamical chaos is possible even for a force which is derived from a simple potential. For a given strength of the magnetic field, initial position, and velocity of the particle, the dynamics may be regular, but it may become chaotic when the field is time dependent. Chaotic dynamics is very often if the field is time dependent. Origin of chaos has been explored using the Hamiltonian function of the dynamics in terms of action and angle variables. Applicability of the present study has been discussed with a few examples.

  7. Magnetic field induced anisotropy of 139La spin-lattice relaxation rates in stripe ordered La1.875Ba0.125CuO4

    DOE PAGESBeta

    S. -H. Baek; Gu, G. D.; Utz, Y.; Hucker, M.; Buchner, B.; Grafe, H. -J.

    2015-10-26

    We report 139La nuclear magnetic resonance studies performed on a La1.875Ba0.125CuO4 single crystal. The data show that the structural phase transitions (high-temperature tetragonal → low-temperature orthorhombic → low-temperature tetragonal phase) are of the displacive type in this material. The 139La spin-lattice relaxation rate T–11 sharply upturns at the charge-ordering temperature TCO = 54 K, indicating that charge order triggers the slowing down of spin fluctuations. Detailed temperature and field dependencies of the T–11 below the spin-ordering temperature TSO=40 K reveal the development of enhanced spin fluctuations in the spin-ordered state for H ∥ [001], which are completely suppressed for largemore » fields along the CuO2 planes. Lastly, our results shed light on the unusual spin fluctuations in the charge and spin stripe ordered lanthanum cuprates.« less

  8. Magnetic field induced anisotropy of 139La spin-lattice relaxation rates in stripe ordered La1.875Ba0.125CuO4

    NASA Astrophysics Data System (ADS)

    Baek, S.-H.; Utz, Y.; Hücker, M.; Gu, G. D.; Büchner, B.; Grafe, H.-J.

    2015-10-01

    We report 139La nuclear magnetic resonance studies performed on a La1.875Ba0.125CuO4 single crystal. The data show that the structural phase transitions (high-temperature tetragonal→low-temperature orthorhombic→low-temperature tetragonal phase) are of the displacive type in this material. The 139La spin-lattice relaxation rate T1-1 sharply upturns at the charge-ordering temperature TCO=54 K, indicating that charge order triggers the slowing down of spin fluctuations. Detailed temperature and field dependencies of the T1-1 below the spin-ordering temperature TSO=40 K reveal the development of enhanced spin fluctuations in the spin-ordered state for H ∥[001 ] , which are completely suppressed for large fields along the CuO2 planes. Our results shed light on the unusual spin fluctuations in the charge and spin stripe ordered lanthanum cuprates.

  9. 5f delocalization-induced suppression of quadrupolar order in U(Pd1-xPtx)₃

    DOE PAGESBeta

    Walker, H. C.; Le, M. D.; McEwen, K. A.; Bleckmann, M.; Süllow, S.; Mazzoli, C.; Wilkins, S. B.; Fort, D.

    2011-12-27

    We present bulk magnetic and transport measurements and x-ray resonant scattering measurements on U(Pd1-xPtx)₃ for x=0.005 and 0.01, which demonstrate the high sensitivity of the quadrupolar order in the canonical antiferroquadrupolar ordered system UPd₃ to doping with platinum. Bulk measurements for x=0.005 reveal behavior similar to that seen in UPd₃, albeit at a lower temperature, and x-ray resonant scattering provides evidence of quadrupolar order described by the Qxy order parameter. In contrast, bulk measurements reveal only an indistinct transition in x=0.01, consistent with the observation of short-range quadrupolar order in our x-ray resonant scattering results.

  10. Spin and quadrupolar orders in the spin-1 bilinear-biquadratic model for iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Luo, Cheng; Datta, Trinanjan; Yao, Dao-Xin

    2016-06-01

    Motivated by the recent experimental and theoretical progress of the magnetic properties in iron-based superconductors, we provide a comprehensive analysis of the extended spin-1 bilinear-biquadratic (BBQ) model on the square lattice. Using a variational approach at the mean-field level, we identify the existence of various magnetic phases, including conventional spin dipolar orders (ferro- and antiferromagnet), novel quadrupolar orders (spin nematic), and mixed dipolar-quadrupolar orders. In contrast to the regular Heisenberg model, the elementary excitations of the spin-1 BBQ model are described by the SU(3) flavor-wave theory. By fitting the experimental spin-wave dispersion, we determine the refined exchange couplings corresponding to the collinear antiferromagnetic iron pnictides. We also present the dynamic structure factors of both spin dipolar and quadrupolar components with connections to the future experiments.

  11. Structure and orientational ordering in a fluid of elongated quadrupolar molecules

    NASA Astrophysics Data System (ADS)

    Singh, Ram Chandra

    2013-01-01

    A second-order density-functional theory is used to study the effect of quadrupolar interactions on the isotropic-nematic transition in a system of fluids of elongated molecules interacting via the Gay-Berne potential. The direct pair-correlation functions of the coexisting isotropic fluid that enter in the theory as input information are obtained by solving the Ornstein-Zernike equation using the Percus-Yevick integral equation theory in the (reduced) temperature range of 1.6≤T∗≤3.0 for different densities, temperatures and quadrupole moments. Using the harmonic coefficients of the direct pair-correlation functions, isotropic-nematic phase coexistence and thermodynamic parameters have been calculated. The theoretical results have been compared with the available computer simulation results.

  12. Direct measurements of the magnetic field induced by optically polarized sup 3 He atoms

    SciTech Connect

    Gudoshnikov, S.A.; Snigirev, O.V. ); Kozlov, A.N.; Maslennikov, Y.V.; Serebrjakov, A.Y. )

    1991-03-01

    This paper reports on an alternative magnetic field induced by the standard cell of the optically pumped {sup 3}He magnetometer directly measured by the SQUID-based second-order gradiometer with signal-to-noise ratio higher than 6. The magnitude of the measured field equal to 5 {times} 10{sup {minus}13} T at the 5-cm distance from the cell axis and transverse relaxation time T{sub 2} equal to 7 minutes have been found.

  13. 5f delocalization-induced suppression of quadrupolar order in U(Pd1-xPtx)₃

    SciTech Connect

    Walker, H. C.; Le, M. D.; McEwen, K. A.; Bleckmann, M.; Süllow, S.; Mazzoli, C.; Wilkins, S. B.; Fort, D.

    2011-12-27

    We present bulk magnetic and transport measurements and x-ray resonant scattering measurements on U(Pd1-xPtx)₃ for x=0.005 and 0.01, which demonstrate the high sensitivity of the quadrupolar order in the canonical antiferroquadrupolar ordered system UPd₃ to doping with platinum. Bulk measurements for x=0.005 reveal behavior similar to that seen in UPd₃, albeit at a lower temperature, and x-ray resonant scattering provides evidence of quadrupolar order described by the Qxy order parameter. In contrast, bulk measurements reveal only an indistinct transition in x=0.01, consistent with the observation of short-range quadrupolar order in our x-ray resonant scattering results.

  14. Magnetic field induced anisotropy of 139La spin-lattice relaxation rates in stripe ordered La1.875Ba0.125CuO4

    SciTech Connect

    S. -H. Baek; Gu, G. D.; Utz, Y.; Hucker, M.; Buchner, B.; Grafe, H. -J.

    2015-10-26

    We report 139La nuclear magnetic resonance studies performed on a La1.875Ba0.125CuO4 single crystal. The data show that the structural phase transitions (high-temperature tetragonal → low-temperature orthorhombic → low-temperature tetragonal phase) are of the displacive type in this material. The 139La spin-lattice relaxation rate T–11 sharply upturns at the charge-ordering temperature TCO = 54 K, indicating that charge order triggers the slowing down of spin fluctuations. Detailed temperature and field dependencies of the T–11 below the spin-ordering temperature TSO=40 K reveal the development of enhanced spin fluctuations in the spin-ordered state for H ∥ [001], which are completely suppressed for large fields along the CuO2 planes. Lastly, our results shed light on the unusual spin fluctuations in the charge and spin stripe ordered lanthanum cuprates.

  15. Magnetic-field-induced liquid metal droplet manipulation

    NASA Astrophysics Data System (ADS)

    Kim, Daeyoung; Lee, Jeong-Bong

    2015-01-01

    We report magnetic-field-induced liquid metal droplet on-demand manipulation by coating a liquid metal with ferromagnetic materials. The gallium-based liquid metal alloy has a challenging drawback that it is instantly oxidized in ambient air, resulting in surface wetting on most surfaces. When the oxidized surface of the droplet is coated with ferromagnetic materials, it is non-wettable and can be controlled by applying an external magnetic field. We coated the surface of a liquid metal droplet with either an electroplated CoNiMnP layer or an iron (Fe) particle by simply rolling the liquid metal droplet on an Fe particle bed. For a paper towel, the minimum required magnetic flux density to initiate movement of the ~8 μL Fe-particle-coated liquid metal droplet was 50 gauss. Magnetic-field-induced liquid metal droplet manipulation was investigated under both horizontal and vertical magnetic fields. Compared to the CoNiMnP-electroplated liquid metal droplet, the Fe-particle-coated droplet could be well controlled because Fe particles were uniformly coated on the surface of the droplet. With a maximum applied magnetic flux density of ~1,600 gauss, the CoNiMnP layer on the liquid metal broke down, resulting in fragmentation of three smaller droplets, and the Fe particle was detached from the liquid metal surface and was re-coated after the magnetic field had been removed.

  16. Magnetic-Field Induced Diffraction Patterns from Ferrofluids

    NASA Astrophysics Data System (ADS)

    Rablau, Corneliu; Vaishnava, Prem; Lawes, Gavin; Naik, Ratna

    2011-04-01

    Ferrofluids are stable colloidal suspensions of superparamagnetic nanoparticles in a carrier liquid. We report studies of magneto-optic properties of two ferrofluid systems consisting of tetramethyl-ammonium-hydroxide (TMAH)-coated and of dextran-coated Fe3O4 nanoparticles of nominal sizes of 6 nm and 12 nm respectively suspended in water. Both samples showed superparamagnetic behavior. The static and time-dependent DC-magnetic-field-induced light scattering patterns produced by two orthogonal He-Ne laser beams passing through the ferrofluid samples revealed significant different optical signatures for the two surfactants. Notably, in contrast to the linear diffraction pattern produced by TMAH-coated nanoparticles, a circular diffraction pattern is reported -- for the first time -- in the dextran-coated ferrofluid.

  17. Path-integral Monte Carlo study of asymmetric quantum quadrupolar rotors with fourth-order propagators

    NASA Astrophysics Data System (ADS)

    Park, Sungjin; Shin, Hyeondeok; Kwon, Yongkyung

    2012-08-01

    The recently-proposed fourth-order propagator based on the multi-product expansion has been applied to path-integral Monte Carlo calculations for asymmetric quantum quadruploar rotors fixed at face-centered cubic lattice sites. The rotors are observed to undergo an orientational orderdisorder phase transition at a low temperature when the electric quadrupole-quadrupole interaction is strong enough. At intermediate interaction strength, a further decrease of temperature after the first transition to the ordered phase results in a reentrant transition back to the disordered phase. The theoretical phase diagram of these asymmetric rotors determined by using fourth-order path-integral Monte Carlo calculations is found to be in good quantitative agreement with the experimental one for solid hydrogen deuteride. This leads us to conclude that the fourth-order propagator can be effectively implemented for an accurate path-integral Monte Carlo calculation of a quantum many-body system with rotational degrees of freedom.

  18. Magnetic field induced motion behavior of gas bubbles in liquid

    PubMed Central

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-01-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields. PMID:26867515

  19. Impurities in magnetic-field-induced Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Tsai, Shan-Wen; Maslov, Dmitrii L.; Glazman, Leonid I.

    2001-03-01

    It has been shown recently(C. Biagini, D. L. Maslov, M. Yu. Reizer and L. I. Glazman, `` Magnetic-field-induced Luttinger liquid''), cond-mat/0006407. that a strong magnetic field applied to a bulk metal may induce a Luttinger liquid phase. This is a consequence of the reduced effective dimensionality of charge carriers from 3D to 1D, an effect which is most pronounced in the ultra-quantum limit, when only the lowest Landau level remains populated. We study the effect of impurities in this system. For the case of a point impurity, the calculation of the scattering cross section at a single impurity can be mapped exactly to a 1D problem of tunneling conductance through a barrier for interacting electrons, solved by Yue et al.(D. Yue, L. I. Glazman and K. A. Matveev, Phys. Rev. B 49) (1994) 1966.. Using this mapping, we find that the longitudinal (ɛ=+1) and transverse (ɛ=-1) Drude conductivities exhibit the scaling laws σ_ɛ∝ T^ɛα, where α=2e^2|lnκl_B|/π v_F, and vF and κ are the B-dependent Fermi velocity and screening wavevector, respectively; lB is the magnetic length. The physical reason for such a behavior of the conductivity is the almost 1D form of the Friedel oscillation around a single point impurity in the strong magnetic field.

  20. Magnetic field induced motion behavior of gas bubbles in liquid

    NASA Astrophysics Data System (ADS)

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-02-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields.

  1. Magnetic field induced motion behavior of gas bubbles in liquid.

    PubMed

    Wang, Keliang; Pei, Pucheng; Pei, Yu; Ma, Ze; Xu, Huachi; Chen, Dongfang

    2016-01-01

    The oxygen evolution reaction generally exists in electrochemical reactions. It is a ubiquitous problem about how to control the motion of oxygen bubbles released by the reaction. Here we show that oxygen bubbles during oxygen evolution reaction exhibit a variety of movement patterns in the magnetic field, including directional migration and rotational motion of oxygen bubbles when the magnet in parallel with the electrode, and exclusion movement of oxygen bubbles when the magnet perpendicular to the electrode. The results demonstrate that the direction of oxygen bubbles movement is dependent upon the magnet pole near the electrode, and the kinetics of oxygen bubbles is mainly proportional to intensity of the electromagnetic field. The magnetic-field induced rotational motion of oxygen bubbles in a square electrolyzer can increase liquid hydrodynamics, thus solve the problems of oxygen bubbles coalescence, and uneven distribution of electrolyte composition and temperature. These types of oxygen bubbles movement will not only improve energy saving and metal deposition for energy storage and metal refinery, but also propel object motion in application to medical and martial fields. PMID:26867515

  2. High magnetic field induced changes of gene expression in arabidopsis

    PubMed Central

    Paul, Anna-Lisa; Ferl, Robert J; Meisel, Mark W

    2006-01-01

    Background High magnetic fields are becoming increasingly prevalent components of non-invasive, biomedical imaging tools (such as MRI), thus, an understanding of the molecular impacts associated with these field strengths in biological systems is of central importance. The biological impact of magnetic field strengths up to 30 Tesla were investigated in this study through the use of transgenic Arabidopsis plants engineered with a stress response gene consisting of the alcohol dehydrogenase (Adh) gene promoter driving the β-glucuronidase (GUS) gene reporter. Methods Magnetic field induced Adh/GUS activity was evaluated with histochemical staining to assess tissue specific expression and distribution, and with quantitative, spectrofluometric assays to measure degree of activation. The evaluation of global changes in the Arabidopsis genome in response to exposure to high magnetic fields was facilitated with Affymetrix Gene Chip microarrays. Quantitative analyses of gene expression were performed with quantitative real-time polymerase-chain-reaction (qRT-PCR). Results Field strengths in excess of about 15 Tesla induce expression of the Adh/GUS transgene in the roots and leaves. From the microarray analyses that surveyed 8000 genes, 114 genes were differentially expressed to a degree greater than 2.5 fold over the control. These results were quantitatively corroborated by qRT-PCR examination of 4 of the 114 genes. Conclusion The data suggest that magnetic fields in excess of 15 Tesla have far-reaching effect on the genome. The wide-spread induction of stress-related genes and transcription factors, and a depression of genes associated with cell wall metabolism, are prominent examples. The roles of magnetic field orientation of macromolecules and magnetophoretic effects are discussed as possible factors that contribute to the mounting of this response. PMID:17187667

  3. Calorimetric Study of Magnetic Field-Induced Phase Transitions in - Fulvalenium) -

    NASA Astrophysics Data System (ADS)

    Fortune, Nathanael Alexander

    The particular class of organic conductors known as the Bechgaard salts exhibit a variety of highly anisotropic magnetic, thermal, and electrical phenomena. At low temperatures (below 10 kelvin), the application of a strong magnetic field establishes an effectively lower-dimensional anisotropic Fermi surface, as manifested in a variety of quasi one dimensional and quasi two dimensional thermodynamic and transport properties. Most dramatically, an increasing magnetic field--after suppression of superconductivity, induces a second order phase transition from a metallic to a spin density wave semimetal, followed by a series of first order phase transitions between density wave semimetallic states. This thesis concerns the thermodynamic nature of the low temperature magnetic field induced phase transitions in the Bechgaard charge-transfer salt (TMTSF)2-Cl(O)4. Presented here are the first measurements of the specific heat in magnetic fields up to 30 tesla, as well as the design and construction of a small sample calorimeter capable of operating at dilution refrigerator temperatures in the challenging environment of the high field resistive Bitter magnets. From transport measurements, the existence of a magnetic field induced reentrance into the metallic state has previously been inferred. In this thesis, the unambiguous bulk thermodynamic character of the reentrance is calorimetrically demonstrated. The behavior of the electronic specific heat at the reentrant transition is shown to be consistent with magnetic field enhanced localization. Additionally, quantum oscillations in the high field semimetallic state and the presence of additional structure above the reentrant field are observed. Although these oscillations have also been observed in magnetoresistance and magnetization, the magnitude of the oscillations in the specific heat calls into question all known models for the physical origin of these oscillations.

  4. Magnetic-field-induced ferroelectric polarization reversal in the multiferroic Ge(1-x)Mn(x)Te semiconductor.

    PubMed

    Przybylińska, H; Springholz, G; Lechner, R T; Hassan, M; Wegscheider, M; Jantsch, W; Bauer, G

    2014-01-31

    Ge(1-x)Mn(x)Te is shown to be a multiferroic semiconductor, exhibiting both ferromagnetic and ferroelectric properties. By ferromagnetic resonance we demonstrate that both types of order are coupled to each other. As a result, magnetic-field-induced ferroelectric polarization reversal is achieved. Switching of the spontaneous electric dipole moment is monitored by changes in the magnetocrystalline anisotropy. This also reveals that the ferroelectric polarization reversal is accompanied by a reorientation of the hard and easy magnetization axes. By tuning the GeMnTe composition, the interplay between ferromagnetism and ferroelectricity can be controlled. PMID:24580486

  5. Effects of hole doping by neutron irradiation of magnetic field induced electronic phase transitions in graphite

    SciTech Connect

    Singleton, John; Yaguchi, Hiroshi

    2008-01-01

    We have investigated effects of hole doping by fast-neutron irradiation on the magnetic-field induced phase transitions in graphite using specimens irradiated with fast neutrons. Resistance measurements have been done in magnetic fields of up to above 50 T and at temperatures down to about 1.5 K. The neutron irradiation creates lattice defects acting as acceptors, affecting the imbalance of the electron and hole densities and the Fermi level. We have found that the reentrant field from the field induced state back to the normal state shifts towards a lower field with hole doping, suggestive of the participation of electron subbands in the magnetic-field induced state.

  6. Artificial magnetic field induced by an evanescent wave

    PubMed Central

    Mochol, Małgorzata; Sacha, Krzysztof

    2015-01-01

    Cold atomic gases are perfect laboratories for realization of quantum simulators. In order to simulate solid state systems in the presence of magnetic fields special effort has to be made because atoms are charge neutral. There are different methods for realization of artificial magnetic fields, that is the creation of specific conditions so that the motion of neutral particles mimics the dynamics of charged particles in an effective magnetic field. Here, we consider adiabatic motion of atoms in the presence of an evanescent wave. Theoretical description of the adiabatic motion involves artificial vector and scalar potentials related to the Berry phases. Due to the large gradient of the evanescent field amplitude, the potentials can be strong enough to induce measurable effects in cold atomic gases. We show that the resulting artificial magnetic field is able to induce vortices in a Bose-Einstein condensate trapped close to a surface of a prism where the evanescent wave is created. We also analyze motion of an atomic cloud released from a magneto-optical trap that falls down on the surface of the prism. The artificial magnetic field is able to reflect falling atoms that can be observed experimentally. PMID:25567430

  7. Artificial magnetic field induced by an evanescent wave.

    PubMed

    Mochol, Małgorzata; Sacha, Krzysztof

    2015-01-01

    Cold atomic gases are perfect laboratories for realization of quantum simulators. In order to simulate solid state systems in the presence of magnetic fields special effort has to be made because atoms are charge neutral. There are different methods for realization of artificial magnetic fields, that is the creation of specific conditions so that the motion of neutral particles mimics the dynamics of charged particles in an effective magnetic field. Here, we consider adiabatic motion of atoms in the presence of an evanescent wave. Theoretical description of the adiabatic motion involves artificial vector and scalar potentials related to the Berry phases. Due to the large gradient of the evanescent field amplitude, the potentials can be strong enough to induce measurable effects in cold atomic gases. We show that the resulting artificial magnetic field is able to induce vortices in a Bose-Einstein condensate trapped close to a surface of a prism where the evanescent wave is created. We also analyze motion of an atomic cloud released from a magneto-optical trap that falls down on the surface of the prism. The artificial magnetic field is able to reflect falling atoms that can be observed experimentally. PMID:25567430

  8. Observation of magnetic-field-induced transformation in MnCo0.78Fe0.22Ge alloys with colossal strain output and large magnetocaloric effect

    NASA Astrophysics Data System (ADS)

    Wang, Zilong; Xiu, Pengyuan; Huang, Lian; Nie, Zhihua; Zeng, Junxi; Brown, Dennis E.; Ren, Yang; Wang, Yandong

    2016-05-01

    The thermal, structural and magnetic properties were studied for the hexagonal MnCo0.78Fe0.22Ge alloys, which undergoes a first-order phase transformation from paramagnetic hexagonal phase into ferromagnetic orthorhombic martensite on cooling. Owing to the magnetostructural coupling, large magnetocaloric effect (∆SM=-10.97 J kg-1 K-1) was obtained at 254 K. In-situ synchrotron high-energy X-ray diffraction experiments were conducted to reveal the detailed change in crystallographic structure of phases and the effect of applied magnetic field on phase transformation behaviors. An anomalously huge strain of 11.89% and volume expansion of 4.35% in unit-cell were obtained between martensite and parent phase across the transformation. Furthermore, the magnetic field-induced martensitic transformation was directly evidenced at 250 K, which eventually demonstrates the possibility to achieve magnetic-field-induced strain and large magnetocaloric effect simultaneously.

  9. Magnetic-field-induced quadrupole coupling in the nuclear magnetic resonance of noble-gas atoms and molecules

    SciTech Connect

    Manninen, Pekka; Vaara, Juha; Pyykkoe, Pekka

    2004-10-01

    An analytic response theory formulation for the leading-order magnetic field-induced and field-dependent quadrupole splitting in nuclear magnetic resonance spectra is presented and demonstrated with first-principles calculations for {sup 21}Ne, {sup 36}Ar, and {sup 83}Kr in noble gas atoms. The case of molecules was studied for {sup 33}S in the sulphur hexafluoride molecule, as well as for {sup 47/49}Ti, {sup 91}Zr, and {sup 177,179}Hf in group(IV) tetrahalides. According to our calculations, the hitherto experimentally unknown field-induced quadrupole splitting in molecules rises to 10{sup 2} Hz for {sup 177,179}Hf nuclei in HfF{sub 4} and 10{sup 1} Hz for {sup 47/49}Ti in TiCl{sub 4}, and is hence of observable magnitude.

  10. Observation of the Second-Order Quadrupolar Interaction as a Dominating NMR Relaxation Mechanism in Liquids: The Ultraslow Regime of Motion.

    PubMed

    Shen, Jiahui; Terskikh, Victor; Wu, Gang

    2016-09-01

    We report variable-temperature (VT) (17)O NMR spectra of [5-(17)O]-d-glucose in an aqueous solution and in glycerol at 14.1 and 21.1 T. The VT (17)O NMR data cover a wide range of motion for which the molecular rotational correlation time (τc) of glucose changes more than 5 orders of magnitude. The observed line width of the (17)O NMR signal for [5-(17)O]-d-glucose displays a maximum at ω0τc ≈ 1 and a minimum at ω0τc ≈ 150, where ω0 is the angular Larmor frequency of (17)O. Under the ultraslow motion condition (i.e., ω0τc > 150), the line width of the observed (17)O NMR signal increases drastically with τc, suggesting that the second-order quadrupolar interaction becomes the predominant relaxation mechanism. While this relaxation mechanism has long been predicted by theory, the current study reports the first experimental observation of such a phenomenon. The implications of this new relaxation mechanism on the spectral resolution limit in liquid-state NMR spectroscopy for half-integer spins are discussed. PMID:27525537

  11. Electron correlations in semiconductors: Bulk cohesive properties and magnetic-field-induced Wigner crystal at heterojunctions

    SciTech Connect

    Louie, S.G.; Zhu, X.

    1992-08-01

    A correlated wavefunction variational quantum Monte Carlo approach to the studies of electron exchange and correlation effects in semiconductors is presented. Applications discussed include the cohesive and structural properties of bulk semiconductors, and the magnetic-field-induced Wigner electron crystal in two dimensions. Landau level mixing is shown to be important in determining the transition between the quantum Hall liquid and the Wigner crystal states in the regime of relevant experimental parameters.

  12. Magnetic-Field-Induced Rotation of Polarized Light Emission from Monolayer WS2

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert; Arora, Ashish; Plechinger, Gerd; Nagler, Philipp; Granados del Águila, Andrés; Ballottin, Mariana V.; Christianen, Peter C. M.; Michaelis de Vasconcellos, Steffen; Schüller, Christian; Korn, Tobias; Bratschitsch, Rudolf

    2016-08-01

    We control the linear polarization of emission from the coherently emitting K+ and K- valleys (valley coherence) in monolayer WS2 with an out-of-plane magnetic field of up to 25 T. The magnetic-field-induced valley Zeeman splitting causes a rotation of the emission polarization with respect to the excitation by up to 35° and reduces the polarization degree by up to 16%. We explain both of these phenomena with a model based on two noninteracting coherent two-level systems. We deduce that the coherent light emission from the valleys decays with a time constant of τc=260 fs .

  13. Magnetic-field-induced microwave losses in epitaxial Bi-Sr-Ca-Cu-O films

    SciTech Connect

    Silva, E.; Giura, M.; Marcon, R.; Fastampa, R. ); Balestrino, G.; Marinelli, M.; Milani, E. )

    1992-06-01

    Magnetic-field-induced microwave losses in epitaxial {ital c}-axis-oriented Bi-Sr-Ca-Cu-O films have been observed. At low magnetic field, the behavior of the absorption is qualitatively analogous to that already observed in granular samples. The dominant part is attributed to the dephasing of a network of Josephson junctions. A structural analysis shows evidence of such a network. The dependence of the absorption on the angle between the magnetic field and the {ital a}-{ital b} plane is consistent with this model.

  14. Development of a deformation-tunable quadrupolar microcavity

    NASA Astrophysics Data System (ADS)

    Yang, Juhee; Moon, Songky; Lee, Sang-Bum; Lee, Jai-Hyung; An, Kyungwon; Shim, Jeong-Bo; Lee, Hai-Woong; Kim, Sang-Wook

    2006-08-01

    We have developed a technique for realizing a two-dimensional quadrupolar microcavity with its deformation variable from 0% to 20% continuously. We employed a microjet ejected from a noncircular orifice in order to generate a stationary column with modulated quadrupolar deformation in its cross section. Wavelength redshifts of low-order cavity modes due to shape deformation were measured and were found to be in good agreement with the wave calculation for the same deformation, indicating that the observed deformation is quadrupolar in nature.

  15. Dynamic-angle spinning and double rotation of quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Mueller, K. T.

    1991-07-01

    Nuclear magnetic resonance (NMR) spectroscopy of quadrupolar nuclei is complicated by the coupling of the electric quadrupole moment of the nucleus to local variations in the electric field. The quadrupolar interaction is a useful source of information about local molecular structure in solids, but it tends to broaden resonance lines, causing crowding and overlap in NMR spectra. Magic-angle spinning, which is routinely used to produce high resolution spectra of spin-1/2 nuclei like carbon-13 and silicon-29, is incapable of fully narrowing resonances from quadrupolar nuclei when anisotropic second-order quadrupolar interactions are present. Two new sample-spinning techniques are introduced here that completely average the second-order quadrupolar coupling. Narrow resonance lines are obtained and individual resonances from distinct nuclear sites are identified. In dynamic-angle spinning (DAS) a rotor containing a powdered sample is reoriented between discrete angles with respect to high magnetic field. Evolution under anisotropic interactions at the different angles cancels, leaving only the isotropic evolution of the spin system. In the second technique, double rotation (DOR), a small rotor spins within a larger rotor so that the sample traces out a complicated trajectory in space. The relative orientation of the rotors and the orientation of the larger rotor within the magnetic field are selected to average both first- and second-order anisotropic broadening. The theory of quadrupolar interactions, coherent averaging theory, and motional narrowing by sample reorientation are reviewed with emphasis on the chemical shift anisotropy and second-order quadrupolar interactions experienced by half-odd integer spin quadrupolar nuclei. The DAS and DOR techniques are introduced and illustrated with application to common quadrupolar systems such as sodium-23 and oxygen-17 nuclei in solids.

  16. Dynamic-angle spinning and double rotation of quadrupolar nuclei

    SciTech Connect

    Mueller, K.T. California Univ., Berkeley, CA . Dept. of Chemistry)

    1991-07-01

    Nuclear magnetic resonance (NMR) spectroscopy of quadrupolar nuclei is complicated by the coupling of the electric quadrupole moment of the nucleus to local variations in the electric field. The quadrupolar interaction is a useful source of information about local molecular structure in solids, but it tends to broaden resonance lines causing crowding and overlap in NMR spectra. Magic- angle spinning, which is routinely used to produce high resolution spectra of spin-{1/2} nuclei like carbon-13 and silicon-29, is incapable of fully narrowing resonances from quadrupolar nuclei when anisotropic second-order quadrupolar interactions are present. Two new sample-spinning techniques are introduced here that completely average the second-order quadrupolar coupling. Narrow resonance lines are obtained and individual resonances from distinct nuclear sites are identified. In dynamic-angle spinning (DAS) a rotor containing a powdered sample is reoriented between discrete angles with respect to high magnetic field. Evolution under anisotropic interactions at the different angles cancels, leaving only the isotropic evolution of the spin system. In the second technique, double rotation (DOR), a small rotor spins within a larger rotor so that the sample traces out a complicated trajectory in space. The relative orientation of the rotors and the orientation of the larger rotor within the magnetic field are selected to average both first- and second-order anisotropic broadening. The theory of quadrupolar interactions, coherent averaging theory, and motional narrowing by sample reorientation are reviewed with emphasis on the chemical shift anisotropy and second-order quadrupolar interactions experienced by half-odd integer spin quadrupolar nuclei. The DAS and DOR techniques are introduced and illustrated with application to common quadrupolar systems such as sodium-23 and oxygen-17 nuclei in solids.

  17. Giant Magnetic Field-induced Phase Transitions in Dimeric Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Salili, Seyyed Muhammad; Salamonczyk, Miroslaw; Tamba, Maria-Gabriela; Sprunt, Samuel; Mehl, Georg; Jakli, Antal; Gleeson, James; Kent Group Collaboration; Hull Group Collaboration

    Liquid crystals are responsive to external fields such as electric, magnetic fields. The first experimental observation of dependence of isotropic to nematic phase transition on the applied magnetic field was done using a strong magnetic field on bent-core nematogens and the phase transition temperature exhibited an upshift of 0.7 C at B =30 T. We report on measurements of giant magnetic field-induced isotropic-nematic transition of chainsticks (nunchuks) type dimeric liquid crystals. Upon using the B =25 T split-helix resistive solenoid magnet at NHMFL, we have observed up to 18 C upshift of the isotropic to nematic phase transition temperature at B =22T. We discuss the results within the context of differential thermodynamic potential and the two basic mean-field theories. To our knowledge, this is the first observation of such huge shifts in the phase transitions of thermotropic liquid ctystals

  18. Magnetic-field-induced diameter-selective synthesis of single-walled carbon nanotubes.

    PubMed

    Su, Yanjie; Zhang, Yaozhong; Wei, Hao; Zhang, Liling; Zhao, Jiang; Yang, Zhi; Zhang, Yafei

    2012-03-01

    We report a facile and scalable approach to synthesize single-walled carbon nanotubes (SWNTs) with selected diameter distribution by applying a magnetic field perpendicular to the electric field in the arc plasma region. It is found that this magnetic field-induced diameter-selectivity strategy enables the control of the SWNTs with different diameter distributions in different regions, and the diameter-selective efficiency could be enhanced by modifying the direction of magnetic field. Our results indicate that the motions of the catalysts with different particle sizes, positive carbon ions and electrons are significantly influenced by the magnetic field and electromagnetic force, resulting in the different nucleation and growth processes of SWNTs due to the collective interactions between the magnetic field and arc plasma. This approach would enable a viable route towards the synthesis of SWNTs with desired diameter through the tuning of arc parameters in the arc discharge process. PMID:22301844

  19. Magnetic-Field-Induced Insulator-Conductor Transition in SU(2) Quenched Lattice Gauge Theory

    SciTech Connect

    Buividovich, P.V.; Kharzeev, D.; Chernodub, M.N., Kalaydzhyan, T., Luschevskaya, E.V., and M.I. Polikarpov

    2010-09-24

    We study the correlator of two vector currents in quenched SU(2) lattice gauge theory with a chirally invariant lattice Dirac operator with a constant external magnetic field. It is found that in the confinement phase the correlator of the components of the current parallel to the magnetic field decays much slower than in the absence of a magnetic field, while for other components the correlation length slightly decreases. We apply the maximal entropy method to extract the corresponding spectral function. In the limit of zero frequency this spectral function yields the electric conductivity of quenched theory. We find that in the confinement phase the external magnetic field induces nonzero electric conductivity along the direction of the field, transforming the system from an insulator into an anisotropic conductor. In the deconfinement phase the conductivity does not exhibit any sizable dependence on the magnetic field.

  20. Magnetic-field-induced ferroelectric polarization reversal in magnetoelectric composites revealed by piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Miao, Hongchen; Zhou, Xilong; Dong, Shuxiang; Luo, Haosu; Li, Faxin

    2014-07-01

    Controlling electric polarization (or magnetization) in multiferroic materials with external magnetic fields (or electric fields) is very important for fundamental physics and spintronic devices. Although there has been some progress on magnetic-field-induced polarization reversal in single-phase multiferroics, such behavior has so far never been realized in composites. Here we show that it is possible to reverse ferroelectric polarization using magnetic fields in a bilayer Terfenol-D/PMN-33%PT composite. We realized this by ferroelectric domain imaging using piezoresponse force microscopy (PFM) under applied magnetic field loading. The internal electric field caused by the magnetoelectric (ME) effect in the PMN-PT crystal is considered as the driving force for the 180° polarization switching, and its existence is verified by switching spectroscopy PFM testing under a series of external magnetic fields. A quantitative method is further suggested to estimate the local ME coefficient based on the switching spectroscopy PFM testing results.

  1. Magnetic-field-induced ferroelectric polarization reversal in magnetoelectric composites revealed by piezoresponse force microscopy.

    PubMed

    Miao, Hongchen; Zhou, Xilong; Dong, Shuxiang; Luo, Haosu; Li, Faxin

    2014-08-01

    Controlling electric polarization (or magnetization) in multiferroic materials with external magnetic fields (or electric fields) is very important for fundamental physics and spintronic devices. Although there has been some progress on magnetic-field-induced polarization reversal in single-phase multiferroics, such behavior has so far never been realized in composites. Here we show that it is possible to reverse ferroelectric polarization using magnetic fields in a bilayer Terfenol-D/PMN-33%PT composite. We realized this by ferroelectric domain imaging using piezoresponse force microscopy (PFM) under applied magnetic field loading. The internal electric field caused by the magnetoelectric (ME) effect in the PMN-PT crystal is considered as the driving force for the 180° polarization switching, and its existence is verified by switching spectroscopy PFM testing under a series of external magnetic fields. A quantitative method is further suggested to estimate the local ME coefficient based on the switching spectroscopy PFM testing results. PMID:24953042

  2. Theory of magnetic-field-induced polarization flop in spin-spiral multiferroics

    NASA Astrophysics Data System (ADS)

    Mochizuki, Masahito

    2015-12-01

    The magnetic-field-induced 90∘ flop of ferroelectric polarization P in a spin-spiral multiferroic material TbMnO3 is theoretically studied based on a microscopic spin model. I find that the direction of the P flop or the choice of +Pa or -Pa after the flop is governed by magnetic torques produced by the applied magnetic field H acting on the Mn spins and thus is selected in a deterministic way, in contradistinction to the naively anticipated probabilistic flop. This mechanism resolves a puzzle of the previously reported memory effect in the P direction depending on the history of the magnetic-field sweep, and enables controlled switching of multiferroic domains by externally applied magnetic fields. My Monte-Carlo analysis also uncovers that the magnetic structure in the P ∥a phase under H ∥b is not a previously anticipated simple a b -plane spin cycloid but a conical spin structure.

  3. Magnetic-field-induced rotation of light with orbital angular momentum

    SciTech Connect

    Shi, Shuai; Ding, Dong-Sheng Zhou, Zhi-Yuan; Li, Yan; Zhang, Wei; Shi, Bao-Sen

    2015-06-29

    Light carrying orbital angular momentum (OAM) has attractive applications in the fields of precise optical measurements and high capacity optical communications. We study the rotation of a light beam propagating in warm {sup 87}Rb atomic vapor using a method based on magnetic-field-induced circular birefringence. The dependence of the rotation angle on the magnetic field makes it appropriate for weak magnetic field measurements. We quote a detailed theoretical description that agrees well with the experimental observations. The experiment shown here provides a method to measure the magnetic field intensity precisely and expands the application of OAM-carrying light. This technique has advantage in measurement of magnetic field weaker than 0.5 G, and the precision we achieved is 0.8 mG.

  4. Magnetic-Field-Induced Rotation of Polarized Light Emission from Monolayer WS_{2}.

    PubMed

    Schmidt, Robert; Arora, Ashish; Plechinger, Gerd; Nagler, Philipp; Granados Del Águila, Andrés; Ballottin, Mariana V; Christianen, Peter C M; Michaelis de Vasconcellos, Steffen; Schüller, Christian; Korn, Tobias; Bratschitsch, Rudolf

    2016-08-12

    We control the linear polarization of emission from the coherently emitting K^{+} and K^{-} valleys (valley coherence) in monolayer WS_{2} with an out-of-plane magnetic field of up to 25 T. The magnetic-field-induced valley Zeeman splitting causes a rotation of the emission polarization with respect to the excitation by up to 35° and reduces the polarization degree by up to 16%. We explain both of these phenomena with a model based on two noninteracting coherent two-level systems. We deduce that the coherent light emission from the valleys decays with a time constant of τ_{c}=260  fs. PMID:27563997

  5. Magnetic field-induced helical mode and topological transitions in a topological insulator nanoribbon.

    PubMed

    Jauregui, Luis A; Pettes, Michael T; Rokhinson, Leonid P; Shi, Li; Chen, Yong P

    2016-04-01

    The spin-helical Dirac fermion topological surface states in a topological insulator nanowire or nanoribbon promise novel topological devices and exotic physics such as Majorana fermions. Here, we report local and non-local transport measurements in Bi2Te3 topological insulator nanoribbons that exhibit quasi-ballistic transport over ∼2 μm. The conductance versus axial magnetic flux Φ exhibits Aharonov-Bohm oscillations with maxima occurring alternately at half-integer or integer flux quanta (Φ0 = h/e, where h is Planck's constant and e is the electron charge) depending periodically on the gate-tuned Fermi wavevector (kF) with period 2π/C (where C is the nanoribbon circumference). The conductance versus gate voltage also exhibits kF-periodic oscillations, anti-correlated between Φ = 0 and Φ0/2. These oscillations enable us to probe the Bi2Te3 band structure, and are consistent with the circumferentially quantized topological surface states forming a series of one-dimensional subbands, which undergo periodic magnetic field-induced topological transitions with the disappearance/appearance of the gapless Dirac point with a one-dimensional spin helical mode. PMID:26780658

  6. Magnetic field-induced helical mode and topological transitions in a topological insulator nanoribbon

    NASA Astrophysics Data System (ADS)

    Jauregui, Luis A.; Pettes, Michael T.; Rokhinson, Leonid P.; Shi, Li; Chen, Yong P.

    2016-04-01

    The spin-helical Dirac fermion topological surface states in a topological insulator nanowire or nanoribbon promise novel topological devices and exotic physics such as Majorana fermions. Here, we report local and non-local transport measurements in Bi2Te3 topological insulator nanoribbons that exhibit quasi-ballistic transport over ∼2 μm. The conductance versus axial magnetic flux Φ exhibits Aharonov–Bohm oscillations with maxima occurring alternately at half-integer or integer flux quanta (Φ0 = h/e, where h is Planck's constant and e is the electron charge) depending periodically on the gate-tuned Fermi wavevector (kF) with period 2π/C (where C is the nanoribbon circumference). The conductance versus gate voltage also exhibits kF-periodic oscillations, anti-correlated between Φ = 0 and Φ0/2. These oscillations enable us to probe the Bi2Te3 band structure, and are consistent with the circumferentially quantized topological surface states forming a series of one-dimensional subbands, which undergo periodic magnetic field-induced topological transitions with the disappearance/appearance of the gapless Dirac point with a one-dimensional spin helical mode.

  7. High Magnetic Field-Induced Birefringence in Lyotropic Chromonic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Ostapenko, T.; Nastishin, Yu.; Gleeson, J. T.; Sprunt, S. N.; Lavrentovich, O. D.; Collings, P. J.

    2009-03-01

    We studied the effect of magnetic-field induced birefringence of a 14% solution of disodium cromoglycate (DSCG) in water at temperatures above the nematic-isotropic coexistence region. According to Landau-deGennes mean field theory, we expect to find a linear relationship between the inverse of the induced birefringence, δn, and the quantity (T-T*), where T* is the stability limit of the isotropic phase. Using the 31 T resistive magnet at the National High Magnetic Field Laboratory, we observed that, as we increase the temperature above the coexistence region, we deviate from this linear dependence. Our data shows that δn goes to zero, whereas Landau-deGennes predicts that δn should decrease asymptotically. This may be due to the lack of isodesmic aggregate formation at a finite temperature above the coexistence region.Supported by NSF (DMR-0710544 and DMR-0606160). Work performed at NHMFL, supported by NSF cooperative agreements DMR-0084173, the State of Florida and the DOE.

  8. Fast deswelling of nanocomposite polymer hydrogels via magnetic field-induced heating for emerging FO desalination.

    PubMed

    Razmjou, Amir; Barati, Mohammad Reza; Simon, George P; Suzuki, Kiyonori; Wang, Huanting

    2013-06-18

    Freshwater shortage is one of the most pressing global issues. Forward osmosis (FO) desalination technology is emerging for freshwater production from saline water, which is potentially more energy-efficient than the current reverse osmosis process. However, the lack of a suitable draw solute is the major hurdle for commercial implementation of the FO desalination technology. We have previously reported that thermoresponsive hydrogels can be used as the draw agent for a FO process, and this new hydrogel-driven FO process holds promise for further development for practical application. In the present work, magnetic field-induced heating is explored for the purpose of developing a more effective way to recover water from swollen hydrogel draw agents. The composite hydrogel particles are prepared by copolymerization of sodium acrylate and N-isopropylacrylamide in the presence of magnetic nanoparticles (γ-Fe2O3, <50 nm). The results indicate that the magnetic heating is an effective and rapid method for dewatering of hydrogels by generating the heat more uniformly throughout the draw agent particles, and thus, a dense skin layer commonly formed via conventional heating from the outside of the particle is minimized. The FO dewatering performance is affected by the loading of magnetic nanoparticles and magnetic field intensity. Significantly enhanced liquid water recovery (53%) is achieved under magnetic heating, as opposed to only around 7% liquid water recovery obtained via convection heating. Our study shows that the magnetic heating is an attractive alternative stimulus for the extraction of highly desirable liquid water from the draw agent in the polymer hydrogel-driven forward osmosis process. PMID:23663180

  9. Magnetic-field-induced DNA strand breaks in brain cells of the rat.

    PubMed Central

    Lai, Henry; Singh, Narendra P

    2004-01-01

    In previous research, we found that rats acutely (2 hr) exposed to a 60-Hz sinusoidal magnetic field at intensities of 0.1-0.5 millitesla (mT) showed increases in DNA single- and double-strand breaks in their brain cells. Further research showed that these effects could be blocked by pretreating the rats with the free radical scavengers melatonin and N-tert-butyl-alpha-phenylnitrone, suggesting the involvement of free radicals. In the present study, effects of magnetic field exposure on brain cell DNA in the rat were further investigated. Exposure to a 60-Hz magnetic field at 0.01 mT for 24 hr caused a significant increase in DNA single- and double-strand breaks. Prolonging the exposure to 48 hr caused a larger increase. This indicates that the effect is cumulative. In addition, treatment with Trolox (a vitamin E analog) or 7-nitroindazole (a nitric oxide synthase inhibitor) blocked magnetic-field-induced DNA strand breaks. These data further support a role of free radicals on the effects of magnetic fields. Treatment with the iron chelator deferiprone also blocked the effects of magnetic fields on brain cell DNA, suggesting the involvement of iron. Acute magnetic field exposure increased apoptosis and necrosis of brain cells in the rat. We hypothesize that exposure to a 60-Hz magnetic field initiates an iron-mediated process (e.g., the Fenton reaction) that increases free radical formation in brain cells, leading to DNA strand breaks and cell death. This hypothesis could have an important implication for the possible health effects associated with exposure to extremely low-frequency magnetic fields in the public and occupational environments. PMID:15121512

  10. Thermodynamics of the magnetic-field-induced "normal" state in an underdoped high Tc superconductor

    NASA Astrophysics Data System (ADS)

    Riggs, Scott Chandler

    High magnetic fields are used to kill superconductivity and probe what happens to system when it cannot reach the ideal ground state, i.e. what is the normal-state ground state? Early work in High-Tc, where the application of magnetic field destroyed the zero resistance state and recovered a resistivity value that connected continuously with the zero field curve, lead people to believe this magnetic-field-induced-state had fully driven the system normal, revealing the true underlying ground state, without any vestige of superconductivity. Many experiments done in this region of phase space have results interpreted as coming from the low energy ground state excitations. With the emergence of ultra-clean crystals in a unique family of hole doped high-Tc superconductors, YBa2Cu3O 7-delta, YBCO, a new and highly unexpected phenomena of quantum oscillations were discovered, and they followed the standard Liftshitz-Kosevich (LK) theory for a normal metal. The results suddenly made the problem of high-T c appear to be analogous to superconductivity in the organics, which is brought about by a wave-vector nesting and Fermi surface reconstruction. The only problem, it appeared, that needed to be reconciled was with Angle Resolved Photo-Emission Spectroscopy (ARPES) and Scanning Tunneling Microscopy (STM) data that claimed to see no such Fermi surface, instead only "arcs", a set of disconnected segments in the Brillouin zone which quasiparticle peaks are observed at the Fermi energy, which in a mean field description does not allow for a continuous Fermi surface contour. These two discrepancies led to the "arc vs pocket" debate, which is still unresolved. The other kink in the quantum oscillation armor is that, to this date, quantum oscillations in the hole-doped cuprates have only been seen in YBCO, the only cuprate structure to have CuO chains, which conduct and are located in between two CuO2 superconducting planes in the unit cell. In an attempt to reconcile the "arc vs

  11. The magnetic-field-induced transition from an expanding plasma to a double layer containing expanding plasma

    SciTech Connect

    Charles, C.; Boswell, R. W.

    2007-11-12

    The magnetic-field-induced transition from a simple expansion to a double layer is experimentally investigated in an argon low pressure radio frequency helicon source plasma. When the magnetic field is increased from 30 to 140 G in the plasma source, an abrupt increase in the plasma density and upstream potential is measured at 50 G. In the downstream plasma, the plasma density and potential show a small decrease with increasing magnetic field and no abrupt change. When the upstream jump is measured, simultaneous measurements in the downstream plasma show an ion beam characteristic of a double layer near the source exit.

  12. High-field QCPMG NMR of large quadrupolar patterns using resistive magnets.

    PubMed

    Hung, Ivan; Shetty, Kiran; Ellis, Paul D; Brey, William W; Gan, Zhehong

    2009-12-01

    Spectroscopy in a high magnetic field reduces second-order quadrupolar shift while increasing chemical shift. It changes the scale between quadrupolar and chemical shift of half-integer quadrupolar spins. The application of QCPMG multiple echo for acquiring large quadrupolar pattern under the high magnetic field of a 25 T resistive magnet is presented for acquiring large quadrupolar patterns. It shows that temporal field fluctuations and spatial homogeneity of the Keck magnet at the NHMFL contribute about +/- 20 ppm in line broadening. NMR patterns which have breadths of hundreds to thousands of kilohertz can be efficiently recorded using a combination of QCPMG and magnetic field stepping with negligible hindrance from the inhomogeneity and field fluctuations of powered magnets. PMID:19913391

  13. Large magnetic field-induced work output in a NiMnGa seven-layered modulated martensite

    NASA Astrophysics Data System (ADS)

    Pagounis, E.; Szczerba, M. J.; Chulist, R.; Laufenberg, M.

    2015-10-01

    We report the performance of a Ni-Mn-Ga single crystal with a seven-layered lattice modulation (14M martensite), demonstrating large actuation work output driven by an external magnetic field. A magnetic field-induced strain of 11.2%, a twinning stress of 0.64 MPa, and a magneto-crystalline anisotropy energy of 195 kJ/m3 are measured at room temperature, which exceed the best results reported in Ni-Mn-Ga 14M martensites. The produced magnetically induced work output of about 70 kJ/m3 makes the material attractive for actuator applications. Detailed XRD investigation reveals that the studied 14M martensite is stress-induced. With increasing compression stress, the stress-induced intermartensitic transformation sequence 10M → 14M → NM was demonstrated.

  14. Colloidal Stability and Magnetic Field-Induced Ordering of Magnetorheological Fluids Studied with a Quartz Crystal Microbalance

    PubMed Central

    Rodriguez-López, Jaime; Castro, Pedro; de Vicente, Juan; Johannsmann, Diethelm; Elvira, Luis; Morillas, Jose R.; Montero de Espinosa, Francisco

    2015-01-01

    This work proposes the use of quartz crystal microbalances (QCMs) as a method to analyze and characterize magnetorheological (MR) fluids. QCM devices are sensitive to changes in mass, surface interactions, and viscoelastic properties of the medium contacting its surface. These features make the QCM suitable to study MR fluids and their response to variable environmental conditions. MR fluids change their structure and viscoelastic properties under the action of an external magnetic field, this change being determined by the particle volume fraction, the magnetic field strength, and the presence of thixotropic agents among other factors. In this work, the measurement of the resonance parameters (resonance frequency and dissipation factor) of a QCM are used to analyze the behavior of MR fluids in static conditions (that is, in the absence of external mechanical stresses). The influence of sedimentation under gravity and the application of magnetic fields on the shifts of resonance frequency and dissipation factor were measured and discussed in the frame of the coupled resonance produced by particles touching the QCM surface. Furthermore, the MR-fluid/QCM system has a great potential for the study of high-frequency contact mechanics because the translational and rotational stiffness of the link between the surface and the particles can be tuned by the magnetic field. PMID:26690152

  15. Colloidal Stability and Magnetic Field-Induced Ordering of Magnetorheological Fluids Studied with a Quartz Crystal Microbalance.

    PubMed

    Rodriguez-López, Jaime; Castro, Pedro; de Vicente, Juan; Johannsmann, Diethelm; Elvira, Luis; Morillas, Jose R; Montero de Espinosa, Francisco

    2015-01-01

    This work proposes the use of quartz crystal microbalances (QCMs) as a method to analyze and characterize magnetorheological (MR) fluids. QCM devices are sensitive to changes in mass, surface interactions, and viscoelastic properties of the medium contacting its surface. These features make the QCM suitable to study MR fluids and their response to variable environmental conditions. MR fluids change their structure and viscoelastic properties under the action of an external magnetic field, this change being determined by the particle volume fraction, the magnetic field strength, and the presence of thixotropic agents among other factors. In this work, the measurement of the resonance parameters (resonance frequency and dissipation factor) of a QCM are used to analyze the behavior of MR fluids in static conditions (that is, in the absence of external mechanical stresses). The influence of sedimentation under gravity and the application of magnetic fields on the shifts of resonance frequency and dissipation factor were measured and discussed in the frame of the coupled resonance produced by particles touching the QCM surface. Furthermore, the MR-fluid/QCM system has a great potential for the study of high-frequency contact mechanics because the translational and rotational stiffness of the link between the surface and the particles can be tuned by the magnetic field. PMID:26690152

  16. Magnetic-field-induced ferroelectric polarization flop under pressure in TbMnO3

    NASA Astrophysics Data System (ADS)

    Aoyama, Takuya; Iyama, Ayato; Shimizu, Katsuya; Kimura, Tsuyoshi

    2015-03-01

    Magnetoelectric properties of multiferroic TbMnO3 with a cycloidal spiral spin order were investigated as functions of applied pressure and magnetic field. We found that a flop of ferroelectric polarization occurs by applying a magnetic field along the a axis under 2-3 GPa below the Néel temperature of Tb moments. A possible origin of the magnetoelectric transition is discussed based on the observed pressure and magnetic-field profiles of the ferroelectric polarization and the dielectric relaxation. This flop would originate from the 90° rotation of the cycloidal spiral plane from the bc plane to the ab plane.

  17. Charge rearrangement in magnetite: from magnetic field induced easy axis switching to femtoseconds electronic processes

    NASA Astrophysics Data System (ADS)

    Kąkol, Z.; Kozłowski, A.; Kołodziej, T.; Przewoźnik, J.

    2015-02-01

    Magnetite is the oldest magnet and the first material where the concept of a strong correlations driven metal-insulator transition was suggested and found at TV = 124 K in the so-called Verwey phase transformation. Recently, the structure below TV was solved revealing subtle electronic structure in the form of trimeron lattice that, according to yet another recent communication, may be switched within femtosecond range. In this review article, we argue that the same change of trimeron lattice can be achieved by a magnetic field, in the phenomenon called the easy axis switching. The results of many of our experiments show that although this process is best viewed by magnetization studies, it is also reflected in magnetostriction, causes some changes in electronic transport and can be observed microscopically by NMR that proved electronic order alteration. All those facts suggest that the axis switching process observed and studied by us is intimately linked with the fast change of electronic trimeron order mentioned above.

  18. Magnetic-field-induced nematic-nematic phase separation and droplet formation in colloidal goethite.

    PubMed

    van den Pol, E; Verhoeff, A A; Lupascu, A; Diaconeasa, M A; Davidson, P; Dozov, I; Kuipers, B W M; Thies-Weesie, D M E; Vroege, G J

    2011-05-18

    We demonstrate the suitability of polarization microscopy to study the recently discovered (parallel) nematic-(perpendicular) nematic phase separation. This novel type of phase transition is induced by applying an external magnetic field to a nematic liquid crystal of boardlike colloidal goethite and is due to an interplay between the intrinsic magnetic properties of goethite and the collective effect of liquid crystal formation. It is shown that the intense ochre colour of goethite does not preclude the use of polarization microscopy and interference colours, and that dichroism can give valuable qualitative information on the nature of the phases, their anchoring and their sedimentation and order parameter profiles. We also apply these techniques to study 'nematic-nematic tactoids': nematic droplets sedimenting within a nematic medium with mutually perpendicular orientations. PMID:21525548

  19. Successive Magnetic-Field-Induced Transitions and Colossal Magnetoelectric Effect in Ni_{3}TeO_{6}.

    PubMed

    Kim, Jae Wook; Artyukhin, S; Mun, E D; Jaime, M; Harrison, N; Hansen, A; Yang, J J; Oh, Y S; Vanderbilt, D; Zapf, V S; Cheong, S-W

    2015-09-25

    We report the discovery of a metamagnetic phase transition in a polar antiferromagnet Ni_{3}TeO_{6} that occurs at 52 T. The new phase transition accompanies a colossal magnetoelectric effect, with a magnetic-field-induced polarization change of 0.3 μC/cm^{2}, a value that is 4 times larger than for the spin-flop transition at 9 T in the same material, and also comparable to the largest magnetically induced polarization changes observed to date. Via density-functional calculations we construct a full microscopic model that describes the data. We model the spin structures in all fields and clarify the physics behind the 52 T transition. The high-field transition involves a competition between multiple different exchange interactions which drives the polarization change through the exchange-striction mechanism. The resultant spin structure is rather counterintuitive and complex, thus providing new insights on design principles for materials with strong magnetoelectric coupling. PMID:26451580

  20. Magnetic field induced directional dichroism of spin waves in multiferroic BiFeO3 at THz frequencies

    NASA Astrophysics Data System (ADS)

    Nagel, Urmas; Rõõm, T.; Bordács, S.; Kézsmárki, I.; Yi, H. T.; Cheong, S.-W.; Lee, Jun Hee; Fishman, Randy S.

    2015-03-01

    Using far infrared spectroscopy in high magnetic fields we show that spin excitations in BiFeO3 simultaneously interact with the electric and magnetic field components of light resulting in directional dichroism (DD) of absorption. DD in BiFeO3 arises because an applied static magnetic field induces a toroidal moment in the cycloidal spin structure. Strong DD is observed even in the room-temperature state of the material. The results are explained on the microscopic level as an interplay of five different interactions: isotropic exchange couplings between nearest and next nearest neighbors, an easy-axis anisotropy along the ferroelectric polarization, Dzyaloshinskii-Moriya (DM) interaction that creates the cycloid and DM interaction that causes spin canting. Research sponsored by the Estonian Ministry of Education and Research (IUT23-3), Estonian Science Foundation (ETF8703), and U.S. Department of Energy (JL), Office of Science, Materials Sciences and Engineering Division (RF and JL) and Office of Basis En.

  1. Simple model for coupled magnetic and quadrupolar instabilities in uranium heavy-fermion materials

    SciTech Connect

    Libero, V.L. ); Cox, D.L. )

    1993-08-01

    We present a mean-field calculation of the phase diagram of a simple model of localized moments, in the hexagonal uranium heavy-fermion compounds. The model considers a non-Kramers quadrupolar doublet ground state magnetically coupled with a singlet excited state, favoring in-plane van Vleck magnetism, as has been conjectured for UPt[sub 3]. The Hamiltonian that defines the model is Heisenberg-like in both magnetic and quadrupolar moments. No Kondo-effect physics is included in the calculations. Among our main results are (i) for zero intersite quadrupolar coupling, the magnetic order is achieved by a first-order transition above a critical intersite magnetic coupling value, which becomes second order at higher coupling strengths (ii) for finite intersite quadrupolar coupling, at temperatures below a second-order quadrupolar ordering transition, the minimal magnetic coupling value is increased, but (a) the magnetic ordering temperature is enhanced above this value, and (b) the ordering of first- and second-order transitions in the phase diagram is reversed. By considering the general structure of the Ginsburg-Landau free energy, we argue that the Kondo effect will not modify the shape of the phase diagram, but will modify the quantitative values at which transitions occur.

  2. Probing Quadrupolar Nuclei by Solid-State NMR Spectroscopy: Recent Advances

    SciTech Connect

    Fernandez, Christian; Pruski, Marek

    2011-06-08

    Solid-state nuclear magnetic resonance (NMR) of quadrupolar nuclei has recently undergone remarkable development of capabilities for obtaining structural and dynamic information at the molecular level. This review summarizes the key achievements attained during the last couple of decades in solid-state NMR of both integer spin and half-integer spin quadrupolar nuclei. We provide a concise description of the first- and second-order quadrupolar interactions, and their effect on the static and magic angle spinning (MAS) spectra. Methods are explained for efficient excitation of single- and multiple-quantum coherences, and acquisition of spectra under low- and high-resolution conditions. Most of all, we present a coherent, comparative description of the high-resolution methods for half-integer quadrupolar nuclei, including double rotation (DOR), dynamic angle spinning (DAS), multiple-quantum magic angle spinning (MQMAS), and satellite transition magic angle spinning (STMAS). Also highlighted are methods for processing and analysis of the spectra. Finally, we review methods for probing the heteronuclear and homonuclear correlations between the quadrupolar nuclei and their quadrupolar or spin-1/2 neighbors.

  3. Magnetic field induced enlargement of the regime of critical fluctuations in the classical superconductor V3Si from high-resolution specific heat experiments.

    PubMed

    Zheng, Y; Liu, Y; Toyota, N; Lortz, R

    2015-02-25

    We present high-resolution specific heat data from a high-purity single crystal of the classical superconductor V(3)Si, which reveal tiny lambda-shape anomalies at the superconducting transition superimposed onto the BCS specific heat jump in magnetic fields of 2 T and higher. The appearance of these anomalies is accompanied by a magnetic-field-induced broadening of the superconducting transition. We demonstrate, using scaling relations predicted by the fluctuation models of the 3d-XY and the 3d-lowest-Landau-level (3d-LLL) universality class that the effect of critical fluctuations becomes experimentally observable due to of a magnetic field-induced enlargement of the regime of critical fluctuations. The scaling indicates that a reduction of the effective dimensionality due to the confinement of quasiparticles into low Landau levels is responsible for this effect. PMID:25640214

  4. Quantum Hall effect anomaly and collective modes in the magnetic-field induced spin-density-wave phases of quasi one-dimensional conductors

    NASA Astrophysics Data System (ADS)

    Dupuis, N.; Yakovenko, V. M.

    1999-02-01

    We study the collective modes in the magnetic-field induced spin-density-wave (FISDW) phases experimentally observed in organic conductors of the Bechgaard salts family. In phases that exhibit a sign reversal of the quantum Hall effect (Ribault anomaly), the coexistence of two spin-density waves gives rise to additional long-wavelength collective modes besides the Goldstone modes due to spontaneous translation and rotation symmetry breaking. These modes strongly affect the charge and spin response functions. We discuss some experimental consequences for the Bechgaard salts.

  5. Temperature effect on the magnetic-field-induced type-I-->type-II transition in a CdTe/(Cd,Mn)Te superlattice

    NASA Astrophysics Data System (ADS)

    Peter, G.; Deleporte, E.; Berroir, J. M.; Delalande, C.; Hong, J. M.; Chang, L. L.

    1991-11-01

    We report on the temperature dependence of a magnetic-field-induced type-I-->type-II transition in a (86 Å)/(86 Å) CdTe/Cd0.93Mn0.07Te superlattice. The critical magnetic field at which the transition takes place is found to increase with increasing temperature. This allows an estimation of the relative valence-band offset ranging between 15% and 25%. In addition, the experimental results indicate the existence of magnetic polarons at low temperature (T=1.7 K).

  6. Magnetic Field Induced Phase Transitions in Gd5(Si1.95Ge2.05)Single Crystal and the Anisotropic Magnetocaloric Effect

    SciTech Connect

    H. Tang; V.K. Pecharsky; A.O. Pecharsky; D.L. Schlagel; T.A. Lograsso; K.A. Gschneidner,jr.

    2004-09-30

    The magnetization measurements using a Gd{sub 5}(Si{sub 1.95}Ge{sub 2.05}) single crystal with the magnetic field applied along three crystallographic directions, [001], [010] and [100], were carried out as function of applied field (0-56 kOe) at various temperatures ({approx}5-320 K). The magnetic-field induced phase transformations at temperature above the zero-field critical temperature, i.e. the paramagnetic (PM) {leftrightarrow} ferromagnetic (FM) transitions with application or removal of magnetic field, are found to be temperature dependent and hysteretic. The corresponding critical fields increase with increasing temperature. The magnetic field (H)-temperature (T) phase diagrams have been constructed for the Gd{sub 5}(Si{sub 1.95}Ge{sub 2.05}) single crystal with field along the three directions. A small anisotropy has been observed. The magnetocaloric effect (MCE) has been calculated from the isothermal magnetization data, and the observed anisotropy correlates with H-T phase diagrams. The results are discussed in connection with the magnetic-field induced martensitic-like structural transition observed in the Gd{sub 5}(Si{sub 2}Ge{sub 2})-type compounds.

  7. Resonant Auger for the detection of quadrupolar transitions

    SciTech Connect

    Danger, J.; Le Fevre, P.; Chandesris, D.; Magnan, H.; Jupille, J.; Bourgeois, S.; Eickhoff, T.; Drube, W.

    2003-01-24

    Quadrupolar transitions can play an important role in X-ray absorption spectroscopy, especially when it is used for magnetic measurements, like in X-ray Magnetic Circular Dichroism or Resonant Magnetic Scattering. We show here that resonantly excited Ti KL2,3L2,3 Auger spectra of TiO2 (110) carry a clear signature of quadrupolar transitions from the 1s to localized eg and t2g d-like states. The quadrupolar nature of the observed additional spectator lines are clearly demonstrated by their angular dependence, and their intensity is used to locate and quantify the quadrupolar transitions in the absorption spectrum.

  8. Magnetic field induced lattice effects in a quasi-two-dimensional organic conductor close to the Mott metal-insulator transition

    NASA Astrophysics Data System (ADS)

    de Souza, Mariano; Brühl, Andreas; Strack, Christian; Schweitzer, Dieter; Lang, Michael

    2012-08-01

    We present ultra-high-resolution dilatometric studies in magnetic fields on a quasi-two-dimensional organic conductor κ-(D8-BEDT-TTF)2Cu[N(CN)2]Br, which is located close to the Mott metal-insulator (MI) transition. The obtained thermal expansion coefficient, α(T), reveals two remarkable features: (i) the Mott MI transition temperature TMI=(13.6±0.6) K is insensitive to fields up to 10 T, the highest applied field; (ii) for fields along the interlayer b axis, a magnetic field induced (FI) phase transition at TFI=(9.5±0.5) K is observed above a threshold field Hc˜1 T, indicative of a spin reorientation with strong magnetoelastic coupling.

  9. Magnetic field induced insulator-metal transition in nanocrystalline Pr{sub 0.67}Ca{sub 0.33}MnO{sub 3} compounds: Evidence of large temperature co-efficient of resistance

    SciTech Connect

    Das, Kalipada Das, I.

    2015-05-07

    We report the electronic transport, magneto-transport, and magnetic properties of nanocrystalline Pr{sub 0.67}Ca{sub 0.33}MnO{sub 3} compound. A magnetic field induced insulator—metal transition appears for the external magnetic field higher than 50 kOe. We have obtained large value of the temperature coefficient of resistance (TCR) along with magnetoresistance and field coefficient of resistance (FCR). The value of TCR is 135%/K at 48 K. The calculated magnetoresistance is about −9.8 × 10{sup 7}% for 70 kOe and maximum FCR is about 320%/kOe around 75 K. Due to the application of the external magnetic field, charge ordered state of the compound is destabilized leading to such large values of TCR and FCR. Large values of TCR and FCR along with the large magnetoresistance exhibited by the material is interesting from the application point of view.

  10. Manipulating Migration Behavior of Magnetic Graphene Oxide via Magnetic Field Induced Casting and Phase Separation toward High-Performance Hybrid Ultrafiltration Membranes.

    PubMed

    Xu, Zhiwei; Wu, Tengfei; Shi, Jie; Wang, Wei; Teng, Kunyue; Qian, Xiaoming; Shan, Mingjing; Deng, Hui; Tian, Xu; Li, Cuiyu; Li, Fengyan

    2016-07-20

    Hybrid membranes blended with nanomaterials such as graphene oxide (GO) have great opportunities in water applications due to their multiple functionalities, but they suffer from low modification efficiency of nanomaterials due to the fact that plenty of the nanomaterials are embedded within the polymer matrix during the blending process. Herein, a novel Fe3O4/GO-poly(vinylidene fluoride) (Fe3O4/GO-PVDF) hybrid ultrafiltration membrane was developed via the combination of magnetic field induced casting and a phase inversion technique, during which the Fe3O4/GO nanocomposites could migrate toward the membrane top surface due to magnetic attraction and thereby render the surface highly hydrophilic with robust resistance to fouling. The blended Fe3O4/GO nanocomposites migrated to the membrane surface with the magnetic field induced casting, as verified by X-ray photoelectron spectroscopy, elemental analysis, and energy dispersive X-ray spectroscopy. As a result, the novel membranes exhibited significantly improved hydrophilicity (with a contact angle of 55.0°) and water flux (up to 595.39 L m(-2) h(-1)), which were improved by 26% and 206%, 12% and 49%, 25% and 154%, and 11% and 33% compared with those of pristine PVDF membranes and PVDF hybrid membranes blended with GO, Fe3O4, and Fe3O4/GO without the assistance of magnetic field during membrane casting, respectively. Besides, the novel membranes showed high rejection of bovine serum albumin (>92%) and high flux recovery ratio (up to 86.4%). Therefore, this study presents a novel strategy for developing high-performance hybrid membranes via manipulating the migration of nanomaterials to the membrane surface rather than embedding them in the membrane matrix. PMID:27355273

  11. Nonclassical correlation in NMR quadrupolar systems

    SciTech Connect

    Soares-Pinto, D. O.; Auccaise, R.; Azevedo, E. R. de; Bonagamba, T. J.; Celeri, L. C.; Maziero, J.; Serra, R. M.; Fanchini, F. F.

    2010-06-15

    The existence of quantum correlation (as revealed by quantum discord), other than entanglement and its role in quantum-information processing (QIP), is a current subject for discussion. In particular, it has been suggested that this nonclassical correlation may provide computational speedup for some quantum algorithms. In this regard, bulk nuclear magnetic resonance (NMR) has been successfully used as a test bench for many QIP implementations, although it has also been continuously criticized for not presenting entanglement in most of the systems used so far. In this paper, we report a theoretical and experimental study on the dynamics of quantum and classical correlations in an NMR quadrupolar system. We present a method for computing the correlations from experimental NMR deviation-density matrices and show that, given the action of the nuclear-spin environment, the relaxation produces a monotonic time decay in the correlations. Although the experimental realizations were performed in a specific quadrupolar system, the main results presented here can be applied to whichever system uses a deviation-density matrix formalism.

  12. The polarized interface between quadrupolar insulators: Maxwell stress tensor, surface tension, and potential

    NASA Astrophysics Data System (ADS)

    Slavchov, Radomir I.; Dimitrova, Iglika M.; Ivanov, Tzanko

    2015-10-01

    The quadrupolar Maxwell electrostatic equations predict several qualitatively different results compared to Poisson's classical equation in their description of the properties of a dielectric interface. All interfaces between dielectrics possess surface dipole moment which results in a measurable surface potential jump. The surface dipole moment is conjugated to the bulk quadrupole moment density (the quadrupolarization) similarly to Gauss's relation between surface charge and bulk polarization. However, the classical macroscopic Maxwell equations completely neglect the quadrupolarization of the medium. Therefore, the electrostatic potential distribution near an interface of intrinsic dipole moment can be correctly described only within the quadrupolar macroscopic equations of electrostatics. They predict that near the polarized interface a diffuse dipole layer exists, which bears many similarities to the diffuse charge layer near a charged surface, in agreement with existing molecular dynamics simulation data. It turns out that when the quadrupole terms are kept in the multipole expansion of the laws of electrostatics, the solutions for the potential and the electric field are continuous functions at the surface. A well-defined surface electric field exists, interacting with the adsorbed dipoles. This allows for a macroscopic description of the surface dipole-surface dipole and the surface dipole-bulk quadrupole interactions. They are shown to have considerable contribution to the interfacial tension—of the order of tens of mN/m! To evaluate it, the Maxwell stress tensor in quadrupolar medium is deduced, including the electric field gradient action on the quadrupoles, as well as quadrupolar image force and quadrupolar electrostriction. The dependence of the interfacial tension on the external normal electric field (the dielectrocapillary curve) is predicted and the dielectric susceptibility of the dipolar double layer is related to the quadrupolarizabilities of

  13. Magnetic field induced controllable self-assembly of maghemite nanocrystals: From 3D arrays to 1D nanochains

    NASA Astrophysics Data System (ADS)

    Tang, Yan; Chen, Qianwang; Chen, Rongsheng

    2015-08-01

    A hydrothermal process has been used to synthesize walnut-like maghemite superstructures which can be further self-assembled in a controllable manner into ordered three-dimensional (3D) architectures and one-dimensional (1D) nanochains in the presence of different external magnetic field. The assembly behavior of the maghemite nanoparticles isclosely related to the van der Waals interactions and external-field-induced magnetic dipole interactions. The magnetic properties of these nanostructures are also investigated.

  14. Magnetic-field induced quantum critical points of valence transition in Ce- and Yb-based heavy fermions

    NASA Astrophysics Data System (ADS)

    Watanabe, Shinji; Tsuruta, Atsushi; Miyake, Kazumasa; Flouquet, Jacques

    2009-03-01

    Valence instability and its critical fluctuations have attracted much attention recently in the heavy-electron systems. Valence fluctuations are essentially charge fluctuations, and it is highly non-trivial how the quantum critical point (QCP) as well as the critical end point is controlled by the magnetic field. To clarify this fundamental issue, we have studied the mechanism of how the critical points of the first-order valence transitions are controlled by the magnetic field [1]. We show that the critical temperature is suppressed to be the QCP by the magnetic field and unexpectedly the QCP exhibits nonmonotonic field dependence in the ground-state phase diagram, giving rise to emergence of metamagnetism even in the intermediate valence-crossover regime. The driving force of the field-induced QCP is clarified to be a cooperative phenomenon of Zeeman effect and Kondo effect, which creates a distinct energy scale from the Kondo temperature. This mechanism explains a peculiar magnetic response in CeIrIn5 and metamagnetic transition in YbXCu4 for X=In as well as a sharp contrast between X=Ag and Cd. We present the novel phenomena under the magnetic field to discuss significance of the proximity of the critical points of the first-order valence transition. [1] S. Watanabe et al. PRL100, (2008) 236401.

  15. Electronic disorder and magnetic-field-induced superconductivity enhancement in Fe1+y(Te1-xSex)

    NASA Astrophysics Data System (ADS)

    Hu, Jin; Liu, Tijiang; Qian, Bin; Mao, Zhiqiang

    2012-02-01

    The iron chalcogenide Fe1+y(Te1-xSex) superconductor system exhibits a unique electronic and magnetic phase diagram distinct from those seen in iron pnictides: bulk superconductivity does not appear immediately following the suppression of long-range (π,0) AFM order. Instead, an intermediate phase with weak charge carrier localization appears between AFM order and bulk superconductivity (Liu et al., Nat. Mater. 9, 719 (2010)). In this talk, we report our recent studies on the relationship between the normal state and superconducting properties in Fe1+y(Te1-xSex). We show that the superconducting volume fraction VSC and normal state metallicity significantly increase while the normal state Sommerfeld coefficient γ and Hall coefficient RH drop drastically with increasing Se content in the underdoped superconducting region. Additionally, VSC is surprisingly enhanced by magnetic field in heavily underdoped superconducting samples. The implications of these results will be discussed. Our analyses suggest that the suppression of superconductivity in the underdoped region is associated with electronic disorder caused by incoherent magnetic scattering arising from (π,0) magnetic fluctuations.

  16. Neutron diffraction study of the magnetic-field-induced transition in Mn{sub 3}GaC

    SciTech Connect

    Çakir, Ö.; Acet, M.; Farle, M.; Senyshyn, A.

    2014-01-28

    The antiperovskite Mn{sub 3}GaC undergoes an isostructural cubic–cubic first order transition from a low-temperature, large-cell-volume antiferromagnetic state to a high-temperature, small-cell-volume ferromagnetic state at around 160 K. The transition can also be induced by applying a magnetic field. We study here the isothermal magnetic-field-evolution of the transition as ferromagnetism is stabilized at the expense of antiferromagnetism. We make use of the presence of the two distinct cell volumes of the two magnetic states as a probe to observe by neutron diffraction the evolution of the transition, as the external magnetic field carries the system from the antiferromagnetic to the ferromagnetic state. We show that the large-volume antiferromagnetic and the small-volume ferromagnetic states coexist in the temperature range of the transition. The ferromagnetic state is progressively stabilized as the field increases.

  17. Parallel magnetic field-induced conductance fluctuations in GaAs/AlGaAs ballistic quantum dots.

    NASA Astrophysics Data System (ADS)

    Faniel, S.; Gustin, C.; Melinte, S.; Hackens, B.; Bayot, V.; Shayegan, M.

    2004-03-01

    We present magnetotransport measurements in ballistic quantum dots under a parallel magnetic field. The dots were fabricated on two different GaAs/AlGaAs quantum wells with thicknesses of 15 and and 45 nm and with one and two subbands occupied, respectively. The samples were patterned using e-beam lithography and wet etching. A Cr/Au electrostatic top gate was used in order to tune the width of the dot openings. The measurements were performed down to 300 mK with the magnetic field applied strictly parallel to the plane of the two-dimensional electron gas. For both dots, we observe universal conductance fluctuations and, in the case of the wide quantum well, a reduction of their amplitude at large magnetic field. We discuss these conductance fluctuations in terms of orbital effect(V.I. Fal'ko and T. Jungwirth, Phys Rev B 65), 081306 (2002) and magnetic subband depopulation.

  18. Magnetic field induced extraordinary photoluminescence enhancement in Er{sup 3+}:YVO{sub 4} single crystal

    SciTech Connect

    Zhang, Junpei; Wang, Xia; Tang, Chaoqun; Zhong, Zhiqiang; Ma, Zongwei; Wang, Shaoliang; Han, Yibo; Han, Jun-Bo Li, Liang

    2015-08-28

    A bright green photoluminescence (PL) from {sup 4}S{sub 3∕2} → {sup 4}I{sub 15∕2} emission band in Er{sup 3+}:YVO{sub 4} single crystal has been observed with the excitation of an argon laser at 488.0 nm. More than two orders of PL enhancement have been obtained under the effect of magnetic fields, and the enhancement factor f reaches 170 when the applied magnetic field is 7.7 T under the sample temperature of 4.2 K. Unusually, the PL enhancements only happen at some certain magnetic fields (B{sub c}s), and a decrease of sample temperature will lead to the increase of f and decrease of B{sub c}. The results confirm that this PL enhancement originates from the resonance excitation of the electron transitions induced by the cross of the laser energy and the absorption energy modulated by both the magnetic field and temperature. This special PL enhancement in Er{sup 3+}:YVO{sub 4} single crystal can be applied in the calibration of pulsed high magnetic field, detection of material fine energy structures, and modulation of magneto-optical devices.

  19. Magnetic-field-induced synthesis of Fe{sub 3}O{sub 4} nanorods by a gas–liquid interfacial process: Microstructure control, magnetic and photocatalytic properties

    SciTech Connect

    Zhang, Chun; Mo, Zunli Guo, Ruibin; Teng, Guixiang; Zhao, Guoping

    2014-05-01

    Highlights: • Fe{sub 3}O{sub 4} nanorods were synthesized via a MFI gas–liquid interfacial route. • The morphology of the Fe{sub 3}O{sub 4} nanoparticle can be changed during its growth process. • MF render Fe{sub 3}O{sub 4} nanorods higher degree of crystallinity and better magnetic property. - Abstract: In this paper, we designed a magnetic field (MF) induced gas–liquid interface route to synthesize magnetic Fe{sub 3}O{sub 4} nanorods (NRs). The results showed that the MF can significantly affect the morphology of the particles. In this original method, only relatively inexpensive and environmental chemicals were used. The structure and morphology of the Fe{sub 3}O{sub 4} NRs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry technique. The crystal growth mechanisms in the magnetic field induced process were expounded in detail. The as-synthesized Fe{sub 3}O{sub 4} NRs were successfully used as a catalytic carrier for the photo degradation of phenol.

  20. Magnetic field-induced ferroelectric domain structure evolution and magnetoelectric coupling for [110]-oriented PMN-PT/Terfenol-D multiferroic composites

    NASA Astrophysics Data System (ADS)

    Fang, F.; Jing, W. Q.

    2016-01-01

    Magnetic field-induced polarization rotation and magnetoelectric coupling effects are studied for [110]-oriented (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3/Tb0.3Dy0.7Fe2(PMN-xPT/Terfenol-D) multiferroic composites. Two compositions of the [110]-oriented relaxor ferroelectric single crystals, PMN-28PT and PMN-33PT, are used. In [110]-oriented PMN-28PT, domains of rhombohedral (R) and monoclinic (MB) phases coexist prior to the magnetic loadings. Upon the applied magnetic loadings, phase transition from monoclinic MB to R phase occurs. In [110]-oriented PMN-33PT, domains are initially of mixed orthorhombic (O) and MB phases, and the phase transition from O to MB phase takes place upon the external magnetic loading. Compared to PMN-28PT, the PMN-33PT single crystal exhibits much finer domain boundary structure prior to the magnetic loadings. Upon the magnetic loadings, more domain variants are induced via the phase transition in PMN-33PT than that in PMN-28PT single crystal. The finer domain band structure and more domain variants contribute to stronger piezoelectric activity. As a result, the composite of PMN-33PT/Terfenol-D manifests a stronger ME coupling than PMN-28PT/Terfenol-D composite.

  1. Magnetic-field-induced photocurrent in metal-dielectric-semiconductor heterostructures based on cobalt nanoparticles SiO2(Co)/GaAs

    NASA Astrophysics Data System (ADS)

    Pavlov, V. V.; Lutsev, L. V.; Usachev, P. A.; Astretsov, A. A.; Stognij, A. I.; Novitskii, N. N.; Pisarev, R. V.

    2016-02-01

    Magnetic-field influence on photocurrent in heterostructures of silicon dioxide films with cobalt nanoparticles SiO2(Co) grown on gallium arsenide GaAs substrate has been studied in the avalanche regime at room temperature. High values of magnetic-field-induced photocurrent were found in the vicinity and above the GaAs bandgap of ∼1.4 eV. For photon energies E > 1.4 eV the photocurrent significantly increases, while the avalanche process is suppressed by the magnetic field, and the current flowing through the heterostructure decreases. The photocurrent is enhanced in the SiO2(Co 60 at%)/GaAs heterostructure at the magnetic field H=1.65 kOe by factor of about 10 for the photon energy E=1.5 eV. This phenomenon is explained by a model based on electronic transitions in magnetic fields with the spin-dependent recombination process at deep impurity centers in the SiO2(Co)/GaAs interface region.

  2. Evidence for hidden quadrupolar fluctuations behind the octupole order in Ce0.7La0.3B6 from resonant x-ray diffraction in magnetic fields

    NASA Astrophysics Data System (ADS)

    Matsumura, Takeshi; Michimura, Shinji; Inami, Toshiya; Otsubo, Toru; Tanida, Hiroshi; Iga, Fumitoshi; Sera, Masafumi

    2014-01-01

    The multipole ordered phase in Ce0.7La0.3B6, emerging below 1.5 K and named phase IV, has been studied by resonant x-ray diffraction in magnetic fields. By utilizing diamond x-ray phase plates to rotate the incident linear polarization and a conventional crystal analyzer system, full linear polarization analysis has been performed to identify the order parameters. The analysis shows that the Γ5g(Oyz, Ozx, Oxy) quadrupoles are more induced by the field than the Γ3g (O20 and O22) quadrupoles on the Γ5u (Tx+y +zβ) antiferro-octupole order in phase IV. The problem is that this result is contradictory to a mean-field calculation, which inevitably gives the Γ3g quadrupole as the main induced moment. This result indicates that the Γ5g quadrupole order is close in energy. We consider that a large fluctuation of the Γ5g quadrupole is hidden behind the primary ordering of the Γ5u octupole and that the multipolar fluctuation significantly affects the ordering phenomenon.

  3. Quantum phases of quadrupolar Fermi gases in coupled one-dimensional systems

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Min; Lahrz, M.; Mathey, L.

    2014-01-01

    Following the recent proposal to create quadrupolar gases [Bhongale et al., Phys. Rev. Lett. 110, 155301 (2013), 10.1103/PhysRevLett.110.155301], we investigate what quantum phases can be created in these systems in one dimension. We consider a geometry of two coupled one-dimensional (1D) systems, and derive the quantum phase diagram of ultracold fermionic atoms interacting via quadrupole-quadrupole interactions within a Tomonaga-Luttinger-liquid framework. We map out the phase diagram as a function of the distance between the two tubes and the angle between the direction of the tubes and the quadrupolar moments. The latter can be controlled by an external field. We show that there are two magic angles θB,1c and θB,2c between 0 and π /2, where the intratube quadrupolar interactions vanish and change signs. Adopting a pseudospin language with regard to the two 1D systems, the system undergoes a spin-gap transition and displays a zigzag density pattern, above θB,2c and below θB,1c. Between the two magic angles, we show that polarized triplet superfluidity and a planar spin-density-wave order compete with each other. The latter corresponds to a bond-order solid in higher dimensions. We demonstrate that this order can be further stabilized by applying a commensurate periodic potential along the tubes.

  4. Formation of ordered films of axially bridged aluminum phthalocyanine [(tBu){sub 4}PcAl]{sub 2}O via magnetic field-induced reaction

    SciTech Connect

    Basova, Tamara Berezin, Aleksei; Nadolinny, Vladimir; Peisert, Heiko; Chassé, Thomas; Banimuslem, Hikmat; Hassan, Aseel

    2013-11-28

    The μ-(oxo)bis[tetra-tert-butylphthalocyaninato] aluminum(III) [(tBu){sub 4}PcAl]{sub 2}O films with the crystallites oriented preferably in one direction were obtained via chemical transformation of tetra-tert-butylsubstituted chloroaluminum(III) phthalocyanine (tBu){sub 4}PcAlCl film upon its annealing in magnetic field. A comparative analysis of the influence of post-deposition annealing process without and under applied magnetic field of 1 T, on the orientation and morphology of (tBu){sub 4}PcAlCl and [(tBu){sub 4}PcAl]{sub 2}O films, has been carried out by the methods of UV-vis, Infrared and Raman spectroscopies, XRD as well as atomic force microscopy. The formation of [(tBu){sub 4}PcAl]{sub 2}O films with elongated crystallites having preferential orientation was observed upon heating of the films in magnetic field while annealing without magnetic field under the same conditions does not demonstrate any effect on the structure and morphology of these films. The reasons of the sensitivity of this reaction to the presence of such magnetic field is discussed and studied by electronic paramagnetic resonance spectroscopy.

  5. Formation of ordered films of axially bridged aluminum phthalocyanine [(tBu)4PcAl]2O via magnetic field-induced reaction

    NASA Astrophysics Data System (ADS)

    Basova, Tamara; Berezin, Aleksei; Nadolinny, Vladimir; Peisert, Heiko; Chassé, Thomas; Banimuslem, Hikmat; Hassan, Aseel

    2013-11-01

    The μ-(oxo)bis[tetra-tert-butylphthalocyaninato] aluminum(III) [(tBu)4PcAl]2O films with the crystallites oriented preferably in one direction were obtained via chemical transformation of tetra-tert-butylsubstituted chloroaluminum(III) phthalocyanine (tBu)4PcAlCl film upon its annealing in magnetic field. A comparative analysis of the influence of post-deposition annealing process without and under applied magnetic field of 1 T, on the orientation and morphology of (tBu)4PcAlCl and [(tBu)4PcAl]2O films, has been carried out by the methods of UV-vis, Infrared and Raman spectroscopies, XRD as well as atomic force microscopy. The formation of [(tBu)4PcAl]2O films with elongated crystallites having preferential orientation was observed upon heating of the films in magnetic field while annealing without magnetic field under the same conditions does not demonstrate any effect on the structure and morphology of these films. The reasons of the sensitivity of this reaction to the presence of such magnetic field is discussed and studied by electronic paramagnetic resonance spectroscopy.

  6. High-resolution multiple quantum MAS NMR spectroscopy of half-integer quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Wu, Gang; Rovnyank, David; Sun, Boqin; Griffin, Robert G.

    1996-02-01

    We demonstrate the utility of a two-pulse sequence in obtaining high-resolution solid state NMR spectra of half-integer quadrupolar nuclei with magic-angle-spinning (MAS). The experiment, which utilizes multiple/single-quantum correlation, was first described in a different form by Frydman and Harwood [J. Am. Chem. Soc. 117 (1995) 5367] and yields high-resolution isotropic NMR spectra where shifts are determined by the sum of resonance offset (chemical shift) and second-order quadrupolar effects. The two-pulse sequence described here is shown to provide a higher and more uniform excitation of multiple-quantum coherence than the three-pulse sequence used previously.

  7. Computational analysis of magnetic field induced deposition of magnetic particles in lung alveolus in comparison to deposition produced with viscous drag and gravitational force

    NASA Astrophysics Data System (ADS)

    Krafcik, Andrej; Babinec, Peter; Frollo, Ivan

    2015-04-01

    Magnetic targeting of drugs attached to magnetic nanoparticles with diameter ≈ 100 nm after their intravenous administration is an interesting method of drug delivery widely investigated both theoretically as well as experimentally. Our aim in this study is theoretical analysis of a magnetic aerosol targeting to the lung. Due to lung anatomy magnetic particles up to 5 μm can be safely used, therefore the magnetic force would be stronger, moreover drag force exerted on the particle is according to Stokes law linearly dependent on the viscosity, would be weaker, because the viscosity of the air in the lung is approximately 200 fold smaller than viscosity of the blood. Lung therefore represents unique opportunity for magnetic drug targeting, as we have shown in this study by the analysis of magnetic particle dynamics in a rhythmically expanding and contracting distal and proximal alveolus subjected to high-gradient magnetic field generated by quadrupolar permanent Halbach magnet array.

  8. Second harmonic generation from small gold metallic particles: from the dipolar to the quadrupolar response.

    PubMed

    Nappa, J; Russier-Antoine, I; Benichou, E; Jonin, Ch; Brevet, P F

    2006-11-14

    Hyper Raleigh scattering, a common technique to investigate the second harmonic light scattered from a liquid suspension of molecular compounds and to determine their quadratic hyperpolarizability, has been used for aqueous suspensions of gold nanoparticles, the diameter of which ranges from 20 up to 150 nm. The hyper Rayleigh signal intensity was recorded as a function of the angle of polarization of the incident fundamental wave. For the particles with a diameter smaller than 50 nm, the response is dominated by the dipolar contribution arising from the deviation of the particle shape from that of a perfect sphere. For larger diameter particles, retardation effects in the interaction of the electromagnetic fields with the particles cannot be neglected any longer and the response deviates from the pure dipolar response, exhibiting a strong quadrupolar contribution. It is then shown that in order to quantify the relative magnitude of these two dipolar and quadrupolar contributions, a weighting parameter zeta(V) which equals unity for a pure quadrupolar contribution and vanishes for a pure dipolar response, can be introduced. PMID:17115784

  9. Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

    DOE PAGESBeta

    Perras, Frédéric A.

    2016-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities. Two-dimensional

  10. Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

    SciTech Connect

    Perras, Frederic A.

    2015-12-15

    Here, nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities.

  11. Quantum phases of quadrupolar Fermi gases in optical lattices

    NASA Astrophysics Data System (ADS)

    Bhongale, Satyan; Mathey, Ludwig; Zhao, Erhai; Yellin, Susanne; Lemeshko, Mikhail

    2013-05-01

    We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moment but possessing a significant value of electric quadrupole moment. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities.

  12. Quantum Phases of Quadrupolar Fermi Gases in Optical Lattices

    NASA Astrophysics Data System (ADS)

    Bhongale, S. G.; Mathey, L.; Zhao, Erhai; Yelin, S. F.; Lemeshko, Mikhail

    2013-04-01

    We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moments but possessing a significant value of electric quadrupole moments. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create a topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities.

  13. Site-resolved multiple-quantum filtered correlations and distance measurements by magic-angle spinning NMR: Theory and applications to spins with weak to vanishing quadrupolar couplings.

    PubMed

    Eliav, U; Haimovich, A; Goldbourt, A

    2016-01-14

    We discuss and analyze four magic-angle spinning solid-state NMR methods that can be used to measure internuclear distances and to obtain correlation spectra between a spin I = 1/2 and a half-integer spin S > 1/2 having a small quadrupolar coupling constant. Three of the methods are based on the heteronuclear multiple-quantum and single-quantum correlation experiments, that is, high rank tensors that involve the half spin and the quadrupolar spin are generated. Here, both zero and single-quantum coherence of the half spins are allowed and various coherence orders of the quadrupolar spin are generated, and filtered, via active recoupling of the dipolar interaction. As a result of generating coherence orders larger than one, the spectral resolution for the quadrupolar nucleus increases linearly with the coherence order. Since the formation of high rank tensors is independent of the existence of a finite quadrupolar interaction, these experiments are also suitable to materials in which there is high symmetry around the quadrupolar spin. A fourth experiment is based on the initial quadrupolar-driven excitation of symmetric high order coherences (up to p = 2S, where S is the spin number) and subsequently generating by the heteronuclear dipolar interaction higher rank (l + 1 or higher) tensors that involve also the half spins. Due to the nature of this technique, it also provides information on the relative orientations of the quadrupolar and dipolar interaction tensors. For the ideal case in which the pulses are sufficiently strong with respect to other interactions, we derive analytical expressions for all experiments as well as for the transferred echo double resonance experiment involving a quadrupolar spin. We show by comparison of the fitting of simulations and the analytical expressions to experimental data that the analytical expressions are sufficiently accurate to provide experimental (7)Li-(13)C distances in a complex of lithium, glycine, and water. Discussion

  14. Quadrupolar, Triple [Delta]-Function Potential in One Dimension

    ERIC Educational Resources Information Center

    Patil, S. H.

    2009-01-01

    The energy and parity eigenstates for quadrupolar, triple [delta]-function potential are analysed. Using the analytical solutions in specific domains, simple expressions are obtained for even- and odd-parity bound-state energies. The Heisenberg uncertainty product is observed to have a minimum for a specific strength of the potential. The…

  15. Quadrupolar second-harmonic generation by helical beams and vectorial vortices with radial or azimuthal polarization

    NASA Astrophysics Data System (ADS)

    Mandujano, Miguel G.; Maytorena, Jesús A.

    2013-08-01

    We study the optical second-harmonic radiation (SHG) generated by scattering from a homogeneous centrosymmetric thin composite material illuminated by higher-order Gaussian laser beams. The induced second-order source polarization is taken as of quadrupolar type (E·∇)E, which depends on the inhomogeneity of the incident electric field E. This nonlinear source has the same form as that responsible of the SH signal observed in a composite made of Si nanocrystals embedded uniformly in a SiO2 matrix and that calculated for a thin disordered array of nanospheres. We calculate the SH radiation angular patterns generated by several incident combinations of spatial modes and states of polarizations. In particular, excitation with radially and azimuthally polarized doughnut modes and helical beams carrying orbital angular momentum with linear or circular polarization are considered. We found that this quadrupolar SHG depends sensitively on the transverse structure and polarization of the driving field. The response to ∇E introduces a factor E(E·K) in the Fourier component of the SH scattering amplitude, absent in electric-dipole-allowed SHG, that can give additional nodal lines or rings in the SH angular patterns, changes of the state of polarization, or additional azimuthal phases in the harmonic radiation. For circularly polarized beams with helical phase wave front, we found a selection rule according to which the nonlinear scattering of an optical vortex with charge lω and spin σ=±1 induces a SH vortex field with a spin-dependent charge doubling l2ω=2lω+σ. These features may be useful to identify SHG processes of quadrupolar nature and suggest a way to produce scattered SH radiation with a desired angular pattern and state of polarization.

  16. Quadrupolar and polar anisotropy in end-grafted α-helical poly(γ-benzyl-L-glutamate) on solid substrates

    NASA Astrophysics Data System (ADS)

    Chang, Ying Chih; Frank, Curtis W.; Forstmann, Gerd G.; Johannsmann, Diethelm

    1999-10-01

    Using grazing incidence reflectance Fourier transform infrared spectroscopy (GIR-FTIR) and electro-optic (EO) measurements, we have determined the degree of quadrupolar and polar anisotropy in end-grafted α-helical poly(γ-benzyl-L-glutamate) (PBLG) chains. The results are compared to data obtained on spin-cast and on Langmuir-Blodgett-Kuhn (LBK) films. End-grafted films were prepared by a vapor-deposition-polymerization (VDP) scheme and have thicknesses of up to 70 nm. The quadrupolar order of VDP films, as estimated by the nematic order parameter S, is higher than in spin-cast and LBK films. This result indicates a preferentially perpendicular alignment of PBLG chains in VDP films. Furthermore, after the removal of the physisorbed chains from the grafted films by intensive washing with solvent, the quadrupolar order is lowered while the polar order increases significantly, suggesting that the physisorbed chains might form anti-parallel pairs with the surface-grafted chains.

  17. Low temperature transport properties of the quadrupolar Kondo lattice system PrTi2Al20

    NASA Astrophysics Data System (ADS)

    Sakai, Akito; Nakatsuji, Satoru

    2013-08-01

    We have investigated the low temperature transport properties of the cubic Γ3 compound PrTi2Al20. This is a quadrupolar Kondo lattice system where the nongmagnetic quadrupoles, which form a long-range order at low temperatures, have strong hybridization with the conduction electrons. A sharp drop of the resistivity due to a ferroquadrupole ordering is observed at T Q = 2.0 K. The T 2 dependence of the resistivity and the large Sommerfeld coefficient γ above T Q suggest the formation of a heavy-fermion state. The temperature dependence of the resistivity below T Q does not show a power law but exponential law behavior, indicating the emergence of an anisotropy gap Δ in the collective mode associated with the ferroquadrupole order below T Q. The Fisher-Langer relation holds around T Q, suggesting the higher order scattering processes than those in Born approximation are not dominant for this ferroquadrupole ordering.

  18. Quantum phases of quadrupolar Fermi gases in optical lattices.

    PubMed

    Bhongale, S G; Mathey, L; Zhao, Erhai; Yelin, S F; Lemeshko, Mikhail

    2013-04-12

    We introduce a new platform for quantum simulation of many-body systems based on nonspherical atoms or molecules with zero dipole moments but possessing a significant value of electric quadrupole moments. We consider a quadrupolar Fermi gas trapped in a 2D square optical lattice, and show that the peculiar symmetry and broad tunability of the quadrupole-quadrupole interaction results in a rich phase diagram encompassing unconventional BCS and charge density wave phases, and opens up a perspective to create a topological superfluid. Quadrupolar species, such as metastable alkaline-earth atoms and homonuclear molecules, are stable against chemical reactions and collapse and are readily available in experiment at high densities. PMID:25167282

  19. Two-dimensional nuclear magnetic resonance of quadrupolar systems

    SciTech Connect

    Wang, Shuanhu

    1997-09-17

    This dissertation describes two-dimensional nuclear magnetic resonance theory and experiments which have been developed to study quadruples in the solid state. The technique of multiple-quantum magic-angle spinning (MQMAS) is extensively reviewed and expanded upon in this thesis. Specifically, MQMAS is first compared with another technique, dynamic-angle spinning (DAS). The similarity between the two techniques allows us to extend much of the DAS work to the MQMAS case. Application of MQMAS to a series of aluminum containing materials is then presented. The superior resolution enhancement through MQMAS is exploited to detect the five- and six-coordinated aluminum in many aluminosilicate glasses. Combining the MQMAS method with other experiments, such as HETCOR, greatly expands the possibility of the use of MQMAS to study a large range of problems and is demonstrated in Chapter 5. Finally, the technique switching-angle spinning (SAS) is applied to quadrupolar nuclei to fully characterize a quadrupolar spin system in which all of the 8 NMR parameters are accurately determined. This dissertation is meant to demonstrate that with the combination of two-dimensional NMR concepts and new advanced spinning technologies, a series of multiple-dimensional NMR techniques can be designed to allow a detailed study of quadrupolar nuclei in the solid state.

  20. Population transfer HMQC for half-integer quadrupolar nuclei

    SciTech Connect

    Wang, Qiang; Xu, Jun; Feng, Ningdong; Deng, Feng E-mail: jean-paul.amoureux@univ-lille1.fr; Li, Yixuan; Trébosc, Julien; Lafon, Olivier; Hu, Bingwen; Chen, Qun; Amoureux, Jean-Paul E-mail: jean-paul.amoureux@univ-lille1.fr

    2015-03-07

    This work presents a detailed analysis of a recently proposed nuclear magnetic resonance method [Wang et al., Chem. Commun. 49(59), 6653-6655 (2013)] for accelerating heteronuclear coherence transfers involving half-integer spin quadrupolar nuclei by manipulating their satellite transitions. This method, called Population Transfer Heteronuclear Multiple Quantum Correlation (PT-HMQC), is investigated in details by combining theoretical analyses, numerical simulations, and experimental investigations. We find that compared to instant inversion or instant saturation, continuous saturation is the most practical strategy to accelerate coherence transfers on half-integer quadrupolar nuclei. We further demonstrate that this strategy is efficient to enhance the sensitivity of J-mediated heteronuclear correlation experiments between two half-integer quadrupolar isotopes (e.g., {sup 27}Al-{sup 17}O). In this case, the build-up is strongly affected by relaxation for small T{sub 2}′ and J coupling values, and shortening the mixing time makes a huge signal enhancement. Moreover, this concept of population transfer can also be applied to dipolar-mediated HMQC experiments. Indeed, on the AlPO{sub 4}-14 sample, one still observes experimentally a 2-fold shortening of the optimum mixing time albeit with no significant signal gain in the {sup 31}P-({sup 27}Al) experiments.

  1. Population transfer HMQC for half-integer quadrupolar nuclei.

    PubMed

    Wang, Qiang; Li, Yixuan; Trébosc, Julien; Lafon, Olivier; Xu, Jun; Hu, Bingwen; Feng, Ningdong; Chen, Qun; Amoureux, Jean-Paul; Deng, Feng

    2015-03-01

    This work presents a detailed analysis of a recently proposed nuclear magnetic resonance method [Wang et al., Chem. Commun. 49(59), 6653-6655 (2013)] for accelerating heteronuclear coherence transfers involving half-integer spin quadrupolar nuclei by manipulating their satellite transitions. This method, called Population Transfer Heteronuclear Multiple Quantum Correlation (PT-HMQC), is investigated in details by combining theoretical analyses, numerical simulations, and experimental investigations. We find that compared to instant inversion or instant saturation, continuous saturation is the most practical strategy to accelerate coherence transfers on half-integer quadrupolar nuclei. We further demonstrate that this strategy is efficient to enhance the sensitivity of J-mediated heteronuclear correlation experiments between two half-integer quadrupolar isotopes (e.g., (27)Al-(17)O). In this case, the build-up is strongly affected by relaxation for small T2' and J coupling values, and shortening the mixing time makes a huge signal enhancement. Moreover, this concept of population transfer can also be applied to dipolar-mediated HMQC experiments. Indeed, on the AlPO4-14 sample, one still observes experimentally a 2-fold shortening of the optimum mixing time albeit with no significant signal gain in the (31)P-{(27)Al} experiments. PMID:25747074

  2. SCAM-STMAS: satellite-transition MAS NMR of quadrupolar nuclei with self-compensation for magic-angle misset

    NASA Astrophysics Data System (ADS)

    Ashbrook, Sharon E.; Wimperis, Stephen

    2003-06-01

    Several methods are available for the acquisition of high-resolution solid-state NMR spectra of quadrupolar nuclei with half-integer spin quantum number. Satellite-transition MAS (STMAS) offers an approach that employs only conventional MAS hardware and can yield substantial signal enhancements over the widely used multiple-quantum MAS (MQMAS) experiment. However, the presence of the first-order quadrupolar interaction in the satellite transitions imposes the requirement of a high degree of accuracy in the setting of the magic angle on the NMR probehead. The first-order quadrupolar interaction is only fully removed if the sample spinning angle, χ, equals cos-1(1/ 3) exactly and rotor synchronization is performed. The required level of accuracy is difficult to achieve experimentally, particularly when the quadrupolar interaction is large. If the magic angle is not set correctly, the first-order splitting is reintroduced and the spectral resolution is severely compromised. Recently, we have demonstrated a novel STMAS method (SCAM-STMAS) that is self-compensated for angle missets of up to ±1° via coherence transfer between the two different satellite transitions ST +( mI=+3/2↔+1/2) and ST -( mI=-1/2↔-3/2) midway through the t1 period. In this work we describe in more detail the implementation of SCAM-STMAS and demonstrate its wider utility through 23Na ( I=3/2), 87Rb ( I=3/2), 27Al ( I=5/2), and 59Co ( I=7/2) NMR. We discuss linewidths in SCAM-STMAS and the limits over which angle-misset compensation is achieved and we demonstrate that SCAM-STMAS is more tolerant of temporary spinning rate fluctuations than STMAS, resulting in less " t1 noise" in the two-dimensional spectrum. In addition, alternative correlation experiments, for example involving the use of double-quantum coherences, that similarly display self-compensation for angle misset are investigated. The use of SCAM-STMAS is also considered in systems where other high-order interactions, such as third-order

  3. Magnetic-field-induced irreversible antiferromagnetic-ferromagnetic phase transition around room temperature in as-cast Sm-Co based SmCo7-xSix alloys

    NASA Astrophysics Data System (ADS)

    Feng, D. Y.; Zhao, L. Z.; Liu, Z. W.

    2016-04-01

    A magnetic-field-induced irreversible metamagnetic phase transition from antiferro- to ferromagnetism, which leads to an anomalous initial-magnetization curve lying outside the magnetic hysteresis loop, is reported in arc-melted SmCo7-xSix alloys. The transition temperatures are near room temperature, much higher than other compounds with similar initial curves. Detailed investigation shows that this phenomenon is dependent on temperature, magnetic field and Si content and shows some interesting characteristics. It is suggested that varying interactions between the Sm and Co layers in the crystal are responsible for the formation of a metastable AFM structure, which induces the anomalous phenomenon in as-cast alloys. The random occupation of 3g sites by Si and Co atoms also has an effect on this phenomenon.

  4. Magnetic-Field Induced Superconductor-Insulator Transition in the La{sub 2{minus}{ital x}}Sr{sub {ital x}}CuO{sub 4} System

    SciTech Connect

    Karpinska, K.; Malinowski, A.; Cieplak, M.Z.; Guha, S.; Gershman, S.; Kotliar, G.; Skoskiewicz, T.; Plesiewicz, W.; Berkowski, M.; Lindenfeld, P. |

    1996-09-01

    The magnetoresistance of underdoped La{sub 2{minus}{ital x}}Sr{sub {ital x}}CuO films with {ital x}=0.048 and 0.051 is studied in magnetic fields up to 8.5T and at temperatures down to 30mK. The results indicate that the magnetic-field induced superconductor-insulator (SI) transition is qualitatively different from the reentrant transition described for indium oxide and interpreted as leading to a {open_quote}{open_quote}bosonic insulator{close_quote}{close_quote} phase. The ground state in the absence of superconductivity appears to be insulating. The transitions become narrower below 1K and show that the resistive critical field diverges approaching zero temperature, as has also been observed in other high-{ital T}{sub {ital c}} systems. {copyright} {ital 1996 The American Physical Society.}

  5. Simulation of NMR powder line shapes of quadrupolar nuclei with half-integer spin at low-symmetry sites

    SciTech Connect

    Power, W.P.; Wasylishen, R.E. ); Mooibroek, S. Ltd., Milton, Ontario ); Pettitt, B.A.; Danchura, W. )

    1990-01-25

    At crystallographic sites of low symmetry it is possible for the interactions governing the NMR powder line shape of half-integer spin quadrupolar nuclei to have different orientation dependences. In such cases, it is found that the NMR line shape is sensitive to the relative orientation of the quadrupolar (Q) and chemical shielding (CS) tensors. An analysis of the {sup 133}Cs NMR powder pattern of cesium chromate illustrates the importance of considering such orientation effects. For systems where second-order quadrupolar interactions influence the central (m{sub I} = 1/2 {leftrightarrow} 1/2) transition, the line shape arising from this transition also depends critically on the relative orientation of the Q and CS tensors. It is anticipated that such effects will be important for pin n/2 nuclei (n = 3,5,7, or 9) with large chemical shift ranges and quadrupole moments larger than that of {sup 133}Cs (e.g., {sup 17}O, {sup 51}V, {sup 59}Co, and {sup 63}Cu).

  6. Interaction of Strain and Nuclear Spins in Silicon: Quadrupolar Effects on Ionized Donors

    NASA Astrophysics Data System (ADS)

    Franke, David P.; Hrubesch, Florian M.; Künzl, Markus; Becker, Hans-Werner; Itoh, Kohei M.; Stutzmann, Martin; Hoehne, Felix; Dreher, Lukas; Brandt, Martin S.

    2015-07-01

    The nuclear spins of ionized donors in silicon have become an interesting quantum resource due to their very long coherence times. Their perfect isolation, however, comes at a price, since the absence of the donor electron makes the nuclear spin difficult to control. We demonstrate that the quadrupolar interaction allows us to effectively tune the nuclear magnetic resonance of ionized arsenic donors in silicon via strain and determine the two nonzero elements of the S tensor linking strain and electric field gradients in this material to S11=1.5 ×1022 V /m2 and S44=6 ×1022 V /m2 . We find a stronger benefit of dynamical decoupling on the coherence properties of transitions subject to first-order quadrupole shifts than on those subject to only second-order shifts and discuss applications of quadrupole physics including mechanical driving of magnetic resonance, cooling of mechanical resonators, and strain-mediated spin coupling.

  7. Quadrupolar Kondo effect in uranium heavy-electron materials?

    NASA Technical Reports Server (NTRS)

    Cox, D. L.

    1987-01-01

    The possibility of an electric quadrupole Kondo effect for a non-Kramers doublet on a uranium (U) ion is a cubic metallic host is demonstrated by model calculations showing a Kondo upturn in the resistivity, universal quenching of the quadrupolar moment, and a heavy-electron anomaly in the electronic specific heat. With inclusion of excited crystal-field levels, some of the unusual magnetic-response data in the heavy-electron superconductor UBe13 may be understood. Structural phase transitions at unprecedented low temperatures may occur in U-based heavy-electron materials.

  8. On the relationship between quadrupolar magnetic field and collisionless reconnection

    SciTech Connect

    Smets, R. Belmont, G.; Aunai, N.; Boniface, C.

    2014-06-15

    Using hybrid simulations, we investigate the onset of fast reconnection between two cylindrical magnetic shells initially close to each other. This initial state mimics the plasma structure in High Energy Density Plasmas induced by a laser-target interaction and the associated self-generated magnetic field. We clearly observe that the classical quadrupolar structure of the out-of-plane magnetic field appears prior to the reconnection onset. Furthermore, a parametric study reveals that, with a non-coplanar initial magnetic topology, the reconnection onset is delayed and possibly suppressed. The relation between the out-of-plane magnetic field and the out-of-plane electric field is discussed.

  9. Magnetic-field-induced electric quadrupole moments for relativistic hydrogenlike atoms: Application of the Sturmian expansion of the generalized Dirac-Coulomb Green function

    NASA Astrophysics Data System (ADS)

    Stefańska, Patrycja

    2016-02-01

    We consider a Dirac one-electron atom placed in a weak, static, uniform magnetic field. We show that, to the first order in the strength B of the external field, the only electric multipole moments, which are induced by the perturbation in the atom, are those of an even order. Using the Sturmian expansion of the generalized Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30, 825 (1997), 10.1088/0953-4075/30/4/007; J. Phys. B 30, 2747 (1997), 10.1088/0953-4075/30/11/023], We derive a closed-form expression for the electric quadrupole moment induced in the atom in an arbitrary discrete energy eigenstate. The result, which has the form of a double finite sum involving the generalized hypergeometric functions 3F2 of the unit argument, agrees with the earlier relativistic formula for that quantity, obtained by us for the ground state of the atom.

  10. Vanillin-molecularly targeted extraction of stir bar based on magnetic field induced self-assembly of multifunctional Fe3O4@Polyaniline nanoparticles for detection of vanilla-flavor enhancers in infant milk powders.

    PubMed

    Wu, Jinhua; Yang, Zaiyue; Chen, Ning; Zhu, Wanying; Hong, Junli; Huang, Changgao; Zhou, Xuemin

    2015-03-15

    A molecularly imprinted stir bar was constructed based on Fe3O4@Polyaniline nanoparticles with magnetic field-induced self-assembly process. The monomer, methacrylic acid, was pre-assembled into the pre-polymers with vanillin as template by the formation of hydrogen bonds. After that, the magnetic complexes were generated by the hydrogen bonding, the hydrophobic and π-π interaction between the pre-polymers and Fe3O4@Polyaniline. The complexes were adsorbed on the surface of magnetic stir bar under the magnetic induction, and the coating of vanillin-molecularly imprinted polymers was generated by the one-step copolymerization basing on the cross linking of ethylene glycol dimethacrylate. The molecular imprinting stir bar showed superior selectivity and fast binding kinetics for vanillin, and was used for the enrichment of vanilla-flavor enhancers (vanillin, ethyl maltol and methyl vanillin) in infant milk powders. The results measured by HPLC-UV exhibited good linear ranges of 0.01-100, 0.02-100 and 0.03-100μgmL(-1) with the limit of detection of 2.5-10.0ngmL(-1), and the recoveries were 94.7-98.9%, 82.1-96.7% and 84.5-93.2% with RSD<7.2% for the three enhancers, respectively. PMID:25514645

  11. The Percus-Yevick approximation for quadrupolar molecular fluids

    NASA Astrophysics Data System (ADS)

    Singh, Ram Chandra; Mohan Singh, Braj; Ram, Jokhan

    2009-03-01

    The Percus-Yevick integral equation theory has been solved to study the equilibrium and structural properties of quadrupolar Gay-Berne fluids. The method used involves an expansion of angle-dependent functions appearing in the integral equations in terms of spherical harmonics and the harmonic coefficients are obtained by an iterative algorithm. All the terms of harmonic coefficients which involve l indices up to less than or equal to 6 have been considered. Molecules with length-to-breadth ratios 3.0 and 4.0 have been considered and results are reported for different densities, temperatures, and quadrupole moments. The values of pair correlation functions have been compared with the available computer simulation results.

  12. The Percus-Yevick approximation for quadrupolar molecular fluids.

    PubMed

    Singh, Ram Chandra; Singh, Braj Mohan; Ram, Jokhan

    2009-03-18

    The Percus-Yevick integral equation theory has been solved to study the equilibrium and structural properties of quadrupolar Gay-Berne fluids. The method used involves an expansion of angle-dependent functions appearing in the integral equations in terms of spherical harmonics and the harmonic coefficients are obtained by an iterative algorithm. All the terms of harmonic coefficients which involve l indices up to less than or equal to 6 have been considered. Molecules with length-to-breadth ratios 3.0 and 4.0 have been considered and results are reported for different densities, temperatures, and quadrupole moments. The values of pair correlation functions have been compared with the available computer simulation results. PMID:21693907

  13. Spin squeezing in a quadrupolar nuclei NMR system.

    PubMed

    Auccaise, R; Araujo-Ferreira, A G; Sarthour, R S; Oliveira, I S; Bonagamba, T J; Roditi, I

    2015-01-30

    We have produced and characterized spin-squeezed states at a temperature of 26 °C in a nuclear magnetic resonance quadrupolar system. The experiment was carried out on 133Cs nuclei of spin I=7/2 in a sample of lyotropic liquid crystal. The source of spin squeezing was identified as the interaction between the quadrupole moment of the nuclei and the electric field gradients present within the molecules. We use the spin angular momentum representation to describe formally the nonlinear operators that produce the spin squeezing on a Hilbert space of dimension 2I+1=8. The quantitative and qualitative characterization of this spin-squeezing phenomenon is expressed by a squeezing parameter and squeezing angle developed for the two-mode Bose-Einstein condensate system, as well as by the Wigner quasiprobability distribution function. The generality of the present experimental scheme points to potential applications in solid-state physics. PMID:25679893

  14. Exotic Quadrupolar Phenomena in Non-Kramers Doublet Systems — The Cases of PrT2Zn20 (T = Ir, Rh) and PrT2Al20 (T = V, Ti) —

    NASA Astrophysics Data System (ADS)

    Onimaru, Takahiro; Kusunose, Hiroaki

    2016-08-01

    This paper reviews experimental evidence and the related theoretical background on exotic phenomena arising from local quadrupolar degrees of freedom. Recent extensive studies on praseodymium-based cubic systems, PrT2X20, have revealed that the active quadrupoles in the non-Kramers doublet ground state play a vital role in exhibiting quadrupole orders and superconductivity with underlying peculiar normal paramagnetic electronic states. We focus on four prototype compounds of PrT2X20 (T = Ir, Rh, X = Zn; T = V, Ti, X = Al). Detailed comprehensive comparisons of these compounds have revealed a universal feature of the non-Fermi liquid state emerging from a lattice quadrupolar Kondo effect, and the commonality and individuality of the quadrupolar and superconducting phases. It may be possible to develop a new class of heavy-fermion systems beyond the classic view of heavy fermions on the basis of a concrete understanding of these phenomena.

  15. Fluctuating magnetic field induced resonant activation

    SciTech Connect

    Mondal, Shrabani; Das, Sudip; Baura, Alendu; Bag, Bidhan Chandra

    2014-12-14

    In this paper, we have studied the properties of a Brownian particle at stationary state in the presence of a fluctuating magnetic field. Time dependence of the field makes the system thermodynamically open. As a signature of that the steady state distribution function becomes function of damping strength, intensity of fluctuations and constant parts of the applied magnetic field. It also depends on the correlation time of the fluctuating magnetic field. Our another observation is that the random magnetic field can induce the resonant activation phenomenon. Here correlation time is increased under the fixed variance of the fluctuating field. But if the correlation time (τ) increases under the fixed field strength then the mean first passage time rapidly grows at low τ and it almost converges at other limit. This is sharp contrast to the usual colored noise driven open system case where the mean first passage time diverges exponentially. We have also observed that a giant enhancement of barrier crossing rate occurs particularly at large strength of constant parts of the applied magnetic field even for very weak fluctuating magnetic field. Finally, break down of the Arrhenius result and disappearance of the Kramers’ turn over phenomenon may occur in the presence of a fluctuating magnetic field.

  16. High magnetic field induced spin flip/flop behavior and magnetic phase diagram of CuFe{sub 1−x}Ga{sub x}O{sub 2}

    SciTech Connect

    Shi, L.R.; Xia, Z.C.; Jin, Z.; Wei, M.; Huang, J.W.; Chen, B.R.; Xiao, L.X.; Zuo, H.K.; Ouyang, Z.W.

    2014-11-15

    The structure and magnetic properties of non-magnetic Ga{sup 3+} ion doped CuFe{sub 1−x}Ga{sub x}O{sub 2} (x=0, 0.03, and 0.05) single crystal samples were investigated. X-ray diffraction patterns analysis confirms that the samples are single-phase crystallizing. Doping effect on the magnetic behavior of the ground state and the field-induced spin flip/flop transitions were detected. The transition temperatures and critical magnetic fields of the spin flip/flop, as well as the magnetic hysteresis directly depend on the Ga{sup 3+} doping level. Such doping effects may associate with the competition between dilution effect (partial release of spin frustration) and the induced local magnetic moment, which is the result of the changed magnetic coupling both inter- and intra-planes of Fe ions. Based on the experimental results, the effects of Ga{sup 3+} doping on the spin flip/flop behavior and a detailed high field magnetic diagram were assumed. - Graphical abstract: Temperature dependence of the critical fields for CuFe{sub 1−x}Ga{sub x}O{sub 2} (x=0, 0.03, 0.05). (a) and (b) The magnetic field's parallel and perpendicular cases respectively. In which, the square, circle and triangular represent x=0, 0.03 and 0.05 respectively. - Highlights: • Single crystal samples of CuFe{sub 1−x}Ga{sub x}O{sub 2} (x=0, 0.03 and 0.05) were grown. • Magnetic field dependence of magnetization was measured in pulsed high magnetic field up to 54 T with different temperatures. • The magnetic field induced multi-step-like transitions were observed in all the single crystal samples. • A detailed magnetic diagram was assumed based on the experimental results.

  17. Influence of the Nuclear Electric Quadrupolar Interaction on the Coherence Time of Hole and Electron Spins Confined in Semiconductor Quantum Dots

    NASA Astrophysics Data System (ADS)

    Hackmann, J.; Glasenapp, Ph.; Greilich, A.; Bayer, M.; Anders, F. B.

    2015-11-01

    The real-time spin dynamics and the spin noise spectra are calculated for p and n -charged quantum dots within an anisotropic central spin model extended by additional nuclear electric quadrupolar interactions and augmented by experimental data. Using realistic estimates for the distribution of coupling constants including an anisotropy parameter, we show that the characteristic long time scale is of the same order for electron and hole spins strongly determined by the quadrupolar interactions even though the analytical form of the spin decay differs significantly consistent with our measurements. The low frequency part of the electron spin noise spectrum is approximately 1 /3 smaller than those for hole spins as a consequence of the spectral sum rule and the different spectral shapes. This is confirmed by our experimental spectra measured on both types of quantum dot ensembles in the low power limit of the probe laser.

  18. 2H 2O quadrupolar splitting used to measure water exchange in erythrocytes

    NASA Astrophysics Data System (ADS)

    Kuchel, Philip W.; Naumann, Christoph

    2008-05-01

    The 2H NMR resonance from HDO (D = 2H) in human red blood cells (RBCs) suspended in gelatin that was held stretched in a special apparatus was distinct from the two signals that were symmetrically arranged on either side of it, which were assigned to extracellular HDO. The large extracellular splitting is due to the interaction of the electric quadrupole moment of the 2H nuclei with the electric field gradient tensor of the stretched, partially aligned gelatin. Lack of resolved splitting of the intracellular resonance indicated greatly diminished or absent ordering of the HDO inside RBCs. The separate resonances enabled the application of a saturation transfer method to estimate the rate constants of transmembrane exchange of water in RBCs. However both the theory and the practical applications needed modifications because even in the absence of RBCs the HDO resonances were maximally suppressed when the saturating radio-frequency radiation was applied exactly at the central frequency between the two resonances of the quadrupolar HDO doublet. More statistically robust estimates of the exchange rate constants were obtained by applying two-dimensional exchange spectroscopy (2D EXSY), with back-transformation analysis. A monotonic dependence of the estimates of the efflux rate constants on the mixing time, tmix, used in the 2D EXSY experiment were seen. Extrapolation to tmix = 0, gave an estimate of the efflux rate constant at 15 °C of 31.5 ± 2.2 s -1 while at 25 °C it was ˜50 s -1. These values are close to, but less than, those estimated by an NMR relaxation-enhancement method that uses Mn 2+ doping of the extracellular medium. The basis for this difference is thought to include the high viscosity of the extracellular gel. At the abstract level of quantum mechanics we have used the quadrupolar Hamiltonian to provide chemical shift separation between signals from spin populations across cell membranes; this is the first time, to our knowledge, that this has been

  19. NMR quadrupolar system described as Bose-Einstein-condensate-like system

    SciTech Connect

    Auccaise, R.; Oliveira, I. S.; Sarthour, R. S.; Teles, J.; Bonagamba, T. J.; Azevedo, E. R. de

    2009-04-14

    This paper presents a description of nuclear magnetic resonance (NMR) of quadrupolar systems using the Holstein-Primakoff (HP) formalism and its analogy with a Bose-Einstein condensate (BEC) system. Two nuclear spin systems constituted of quadrupolar nuclei I=3/2 ({sup 23}Na) and I=7/2 ({sup 133}Cs) in lyotropic liquid crystals were used for experimental demonstrations. Specifically, we derived the conditions necessary for accomplishing the analogy, executed the proper experiments, and compared with quantum mechanical prediction for a Bose system. The NMR description in the HP representation could be applied in the future as a workbench for BEC-like systems, where the statistical properties may be obtained using the intermediate statistic, first established by Gentile. The description can be applied for any quadrupolar systems, including new developed solid-state NMR GaAS nanodevices.

  20. PRESTO polarization transfer to quadrupolar nuclei: Implications for dynamic nuclear polarization

    DOE PAGESBeta

    Perras, Frederic A.; Kobayashi, Takeshi; Pruski, Marek

    2015-08-04

    In this study, we show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from 1H to the quadrupolar nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of quadrupolar nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the 1H channel. Thismore » is important in the context of dynamic nuclear polarization (DNP) NMR of quadrupolar nuclei, where the efficient transfer of enhanced 1H polarization is desired to obtain the highest sensitivity.« less

  1. PRESTO polarization transfer to quadrupolar nuclei: Implications for dynamic nuclear polarization

    SciTech Connect

    Perras, Frederic A.; Kobayashi, Takeshi; Pruski, Marek

    2015-08-04

    In this study, we show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from 1H to the quadrupolar nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of quadrupolar nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the 1H channel. This is important in the context of dynamic nuclear polarization (DNP) NMR of quadrupolar nuclei, where the efficient transfer of enhanced 1H polarization is desired to obtain the highest sensitivity.

  2. PRESTO polarization transfer to quadrupolar nuclei: implications for dynamic nuclear polarization.

    PubMed

    Perras, Frédéric A; Kobayashi, Takeshi; Pruski, Marek

    2015-09-21

    We show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from (1)H to the quadrupolar nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of quadrupolar nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the (1)H channel. This is of particular importance in the context of dynamic nuclear polarization (DNP) NMR of quadrupolar nuclei, where the efficient transfer of enhanced (1)H polarization is desired to obtain the highest sensitivity. PMID:26266874

  3. New methods and applications in solid-state NMR spectroscopy of quadrupolar nuclei.

    PubMed

    Ashbrook, Sharon E; Sneddon, Scott

    2014-11-01

    Solid-state nuclear magnetic resonance (NMR) spectroscopy has long been established as offering unique atomic-scale and element-specific insight into the structure, disorder, and dynamics of materials. NMR spectra of quadrupolar nuclei (I > (1)/2) are often perceived as being challenging to acquire and to interpret because of the presence of anisotropic broadening arising from the interaction of the electric field gradient and the nuclear electric quadrupole moment, which broadens the spectral lines, often over several megahertz. Despite the vast amount of information contained in the spectral line shapes, the problems with sensitivity and resolution have, until very recently, limited the application of NMR spectroscopy of quadrupolar nuclei in the solid state. In this Perspective, we provide a brief overview of the quadrupolar interaction, describe some of the basic experimental approaches used for acquiring high-resolution NMR spectra, and discuss the information that these spectra can provide. We then describe some interesting recent examples to showcase some of the more exciting and challenging new applications of NMR spectra of quadrupolar nuclei in the fields of energy materials, microporous materials, Earth sciences, and biomaterials. Finally, we consider the possible directions that this highly informative technique may take in the future. PMID:25296129

  4. Efficient Excited-State Symmetry Breaking in a Cationic Quadrupolar System Bearing Diphenylamino Donors.

    PubMed

    Carlotti, Benedetta; Benassi, Enrico; Fortuna, Cosimo G; Barone, Vincenzo; Spalletti, Anna; Elisei, Fausto

    2016-01-01

    We report a joint experimental and theoretical investigation of a quadrupolar D-π-A(+) -π-D system, the electron donors being diphenylamino groups and the electron acceptor being a methylpyridinium, in comparison with the dipolar D-π-A(+) system. The emission spectra of the two compounds overlap in all the investigated solvents. This finding could be rationalized by TD-DFT calculations: the LUMO-HOMO molecular orbitals involved in the emission transition are localized on the same branch of the quadrupolar structure that becomes the fluorescent portion, corresponding to that of the single-arm compound. Excited-state symmetry breaking has been rarely observed for quadrupolar systems showing negative solvatochromism and is here surprisingly revealed, even in low polarity solvents. Femtosecond transient absorption measurements revealed that an efficient photoinduced intramolecular charge transfer takes place in the quadrupolar chromophore, more efficient than in its dipolar analogue. This result is promising in view of the application of these compounds as novel two-photon absorbing materials. PMID:26510394

  5. Quantifying the Sensitivity of Multipolar (Dipolar, Quadrupolar, and Octapolar) Surface Plasmon Resonances in Silver Nanoparticles: The Effect of Size, Composition, and Surface Coating.

    PubMed

    Bastús, Neus G; Piella, Jordi; Puntes, Víctor

    2016-01-12

    The effect of composition, size, and surface coating on the sensitivity of localized multipolar surface plasmon resonances has been spectroscopically investigated in high-quality silver colloidal solutions with precisely controlled sizes from 10 to 220 nm and well-defined surface chemistry. Surface plasmon resonance modes have been intensively characterized, identifying the size-dependence of dipolar, quadrupolar, and octapolar modes. Modifications of the NP's surface chemistry revealed the higher sensitivity of large sizes, long molecules, thiol groups, and low-order resonance modes. We also extend this study to gold nanoparticles, aiming to compare the sensitivity of both materials, quantifying the higher sensitivity of silver. PMID:26649600

  6. Quadrupolar and anisotropy effects on dephasing in two-electron spin qubits in GaAs

    PubMed Central

    Botzem, Tim; McNeil, Robert P. G.; Mol, Jan-Michael; Schuh, Dieter; Bougeard, Dominique; Bluhm, Hendrik

    2016-01-01

    Understanding the decoherence of electron spins in semiconductors due to their interaction with nuclear spins is of fundamental interest as they realize the central spin model and of practical importance for using them as qubits. Interesting effects arise from the quadrupolar interaction of nuclear spins with electric field gradients, which have been shown to suppress diffusive nuclear spin dynamics and might thus enhance electron spin coherence. Here we show experimentally that for gate-defined GaAs quantum dots, quadrupolar broadening of the nuclear Larmor precession reduces electron spin coherence by causing faster decorrelation of transverse nuclear fields. However, this effect disappears for appropriate field directions. Furthermore, we observe an additional modulation of coherence attributed to an anisotropic electronic g-tensor. These results complete our understanding of dephasing in gated quantum dots and point to mitigation strategies. They may also help to unravel unexplained behaviour in self-assembled quantum dots and III–V nanowires. PMID:27079269

  7. Line shapes in CP/MAS NMR spectra of half-integer quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Hayashi, Shigenobu; Hayamizu, Kikuko

    1993-02-01

    Cross polarization (CP) from 1H to quadrupolar nuclei with S = 3/2 has been carried out under magic-angle-spinning (MAS) conditions for powder samples of Na 2B 4O 7·10H 2O and H 3BO 3. The line shapes in the CP/MAS NMR spectra are different from those in the spectra measured with the single pulse sequence combined with 1H dipolar decoupling. Furthermore, the line shapes are found to be dependent on the measuring conditions such as the pulse amplitude for the quadrupolar nuclei. The spin-locking experiments demonstrate that line shapes in CP/MAS NMR spectra are largely dependent on the spin-locking efficiency.

  8. Quadrupolar and anisotropy effects on dephasing in two-electron spin qubits in GaAs

    NASA Astrophysics Data System (ADS)

    Botzem, Tim; McNeil, Robert P. G.; Mol, Jan-Michael; Schuh, Dieter; Bougeard, Dominique; Bluhm, Hendrik

    2016-04-01

    Understanding the decoherence of electron spins in semiconductors due to their interaction with nuclear spins is of fundamental interest as they realize the central spin model and of practical importance for using them as qubits. Interesting effects arise from the quadrupolar interaction of nuclear spins with electric field gradients, which have been shown to suppress diffusive nuclear spin dynamics and might thus enhance electron spin coherence. Here we show experimentally that for gate-defined GaAs quantum dots, quadrupolar broadening of the nuclear Larmor precession reduces electron spin coherence by causing faster decorrelation of transverse nuclear fields. However, this effect disappears for appropriate field directions. Furthermore, we observe an additional modulation of coherence attributed to an anisotropic electronic g-tensor. These results complete our understanding of dephasing in gated quantum dots and point to mitigation strategies. They may also help to unravel unexplained behaviour in self-assembled quantum dots and III-V nanowires.

  9. Quadrupolar and anisotropy effects on dephasing in two-electron spin qubits in GaAs.

    PubMed

    Botzem, Tim; McNeil, Robert P G; Mol, Jan-Michael; Schuh, Dieter; Bougeard, Dominique; Bluhm, Hendrik

    2016-01-01

    Understanding the decoherence of electron spins in semiconductors due to their interaction with nuclear spins is of fundamental interest as they realize the central spin model and of practical importance for using them as qubits. Interesting effects arise from the quadrupolar interaction of nuclear spins with electric field gradients, which have been shown to suppress diffusive nuclear spin dynamics and might thus enhance electron spin coherence. Here we show experimentally that for gate-defined GaAs quantum dots, quadrupolar broadening of the nuclear Larmor precession reduces electron spin coherence by causing faster decorrelation of transverse nuclear fields. However, this effect disappears for appropriate field directions. Furthermore, we observe an additional modulation of coherence attributed to an anisotropic electronic g-tensor. These results complete our understanding of dephasing in gated quantum dots and point to mitigation strategies. They may also help to unravel unexplained behaviour in self-assembled quantum dots and III-V nanowires. PMID:27079269

  10. Indirect measurement of N-14 quadrupolar coupling for NH3 intercalated in potassium graphite

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Fronko, R. M.; Resing, H. A.

    1987-01-01

    A method for indirect measurement of the nuclear quadrupolar coupling was developed and applied to NH3 molecules in the graphite intercalation compound K(NH3)4.3C24, which has a layered structure with alternating carbon and intercalant layers. Three triplets were observed in the H-1 NMR spectra of the compound. The value of the N-14 quadrupolar coupling constant of NH3 (3.7 MHz), determined indirectly from the H-1 NMR spectra, was intermediate between the gas value of 4.1 MHz and the solid-state value of 3.2 MHz. The method was also used to deduce the (H-1)-(H-1) and (N-14)-(H-1) dipolar interactions, the H-1 chemical shifts, and the molecular orientations and motions of NH3.

  11. High-Resolution NMR of Quadrupolar Nuclei in the Solid State

    SciTech Connect

    Gann, Sheryl Lee

    1995-11-30

    This dissertation describes recent developments in solid state nuclear magnetic resonance (NMR), for the most part involving the use of dynamic-angle spinning (DAS) NMR to study quadrupolar nuclei. Chapter 1 introduces some of the basic concepts and theory that will be referred to in later chapters, such as the density operator, product operators, rotations, coherence transfer pathways, phase cycling, and the various nuclear spin interactions, including the quadrupolar interaction. Chapter 2 describes the theory behind motional averaging experiments, including DAS, which is a technique where a sample is spun sequentially about two axis oriented at different angles with respect to the external magnetic field such that the chemical shift and quadrupolar anisotropy are averaged to zero. Work done on various rubidium-87 salts is presented as a demonstration of DAS. Chapter 3 explains how to remove sidebands from DAS and magic-angle spinning (MAS) experiments, which result from the time-dependence of the Hamiltonian under sample spinning conditions, using rotor-synchronized {pi}-pulses. Data from these experiments, known as DAH-180 and MAH-180, respectively, are presented for both rubidium and lead salts. In addition, the applicability of this technique to double rotation (DOR) experiments is discussed. Chapter 4 concerns the addition of cross-polarization to DAS (CPDAS). The theory behind spin locking and cross polarizing quadrupolar nuclei is explained and a method of avoiding the resulting problems by performing cross polarization at 0{sup o} (parallel) with respect to the magnetic field is presented. Experimental results are shown for a sodium-23 compound, sodium pyruvate, and for oxygen-17 labeled L-akmine. In Chapter 5, a method for broadening the Hartmann-Hahn matching condition under MAS, called variable effective field cross-polarization (VEFCI?), is presented, along with experimental work on adamantane and polycarbonate.

  12. Using tensor light shifts to measure and cancel a cell's quadrupolar frequency shift

    NASA Astrophysics Data System (ADS)

    Peck, S. K.; Lane, N.; Ang, D. G.; Hunter, L. R.

    2016-02-01

    We have developed a technique that uses the tensor light shift to measure and cancel the frequency shift produced by the quadrupolar anisotropy of a vapor cell. We demonstrate the technique on the 6 S1 /2 ,F =4 level of Cs using the D1 transition. The method extends our ability to study quadrupolar wall interactions beyond diamagnetic atoms. We have deduced the twist angle per wall adhesion for cesium on an alkene coating to be θCs -alkene=1.4 mrad . This value is about 37 times larger than the twist angle observed in 131Xe, suggesting that it is not produced by the interaction of the nuclear quadrupole moment with a collisional electric-field gradient. Alternative mechanisms that may be responsible for the observed quadrupolar frequency shifts are discussed. By canceling the cell-induced quadrupole shift we have extended our cells' effective spin-relaxation times by as much as a factor of 2. This cancellation improves magnetometer sensitivity in highly anisotropic cells and could reduce systematic uncertainties in some precision measurements.

  13. Solution deuterium NMR quadrupolar relaxation study of heme mobility in myoglobin

    SciTech Connect

    Johnson, R.D.; La Mar, G.N.; Smith, K.M.; Parish, D.W.; Langry, K.C. )

    1989-01-18

    NMR spectroscopy has been used to monitor the quadrupolar relaxation and motional dynamics of {sup 2}H selectively incorporated into skeletal and side chain positions of the heme in sperm whale myoglobin. The hyperfine shifts of the heme resonances in paramagnetic states of myoglobin allow resolution of the signals of interest, and paramagnetic contributions to the observed line widths are shown to be insignificant. The {sup 2}H line widths for the skeletal positions of deuterohemin-reconstituted myoglobin yield a correlation time identical with that of overall protein tumbling (9 ns at 30{degree}C) and hence reflect an immobile heme group. The {sup 2}H NMR line widths of heme methyl groups exhibit motional narrowing indicative of very rapid internal rotation. Hence the methyl rotation is effectively decoupled from the overall protein tumbling, and the residual quadrupolar line width can be used directly to determine the protein tumbling rate. The {sup 2}H NMR lines from heme vinyl groups were found narrower than those from the heme skeleton. However, the range of quadrupolar coupling constants for sp{sup 2} hybridized C-{sup 2}H bonds does not permit an unequivocal interpretation in terms of mobility. 48 refs., 4 figs.

  14. Solid Effect Between Quadrupolar Transitions in Dilute Cu-Pd Alloys

    NASA Astrophysics Data System (ADS)

    Konzelmann, K.; Majer, G.; Seeger, A.

    1996-06-01

    The paper investigates the Dynamic Solid Effect (DSE) in Nuclear Quadrupole Double Reso-nance (NQDOR) on a system (dilute alloys of CuPd with 8, 42, 210, or 1000 at.ppm Pd) chosen for its simplicity and the possibility to test the theoretical concepts on which the experimental tech-niques (in particular the so-called Berthier-Minier technique for exhibiting the DSE) are based. NQDOR allows to observe the transitions between the Cu nuclear energy levels split by the quadrupolar interaction with the electric field gradients generated by nearby Pd atoms even in dilute alloys, in which the fraction of Cu nuclei experiencing a given field gradient is very small. The DSE permits transitions at frequencies corresponding to the sums or differences of quadrupolar level splittings at neighbouring nuclei and thus gives access to information on the spatial correlation of nuclei accessible to NQDOR studies. The DSE information is shown to be in full accord with the conclusions drawn earlier, on the basis of line-intensity arguments, on the assignment of quadrupo-lar transitions to the first four shells of Cu nuclei surrounding isolated Pd atoms but, in addition, allows to identify the low-frequency NQDOR lines associated with Cu nuclei in the fifth and sixth shells.

  15. Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

    SciTech Connect

    Urban, Jeffry Todd

    2004-12-21

    Experimental and theoretical research conducted in two areas in the field of nuclear magnetic resonance (NMR) spectroscopy is presented: (1) studies of the coherent quantum-mechanical control of the angular momentum dynamics of quadrupolar (spin I > 1/2) nuclei and its application to the determination of molecular structure; and (2) applications of the long-range nuclear dipolar field to novel NMR detection methodologies.The dissertation is organized into six chapters. The first two chapters and associated appendices are intended to be pedagogical and include an introduction to the quantum mechanical theory of pulsed NMR spectroscopy and the time dependent theory of quantum mechanics. The third chapter describes investigations of the solid-state multiple-quantum magic angle spinning (MQMAS) NMR experiment applied to I = 5/2 quadrupolar nuclei. This work reports the use of rotary resonance-matched radiofrequency irradiation for sensitivity enhancement of the I = 5/2 MQMAS experiment. These experiments exhibited certain selective line narrowing effects which were investigated theoretically.The fourth chapter extends the discussion of multiple quantum spectroscopy of quadrupolar nuclei to a mostly theoretical study of the feasibility of enhancing the resolution of nitrogen-14 NMR of large biomolecules in solution via double-quantum spectroscopy. The fifth chapter continues to extend the principles of multiple quantum NMR spectroscopy of quadrupolar nuclei to make analogies between experiments in NMR/nuclear quadrupolar resonance (NQR) and experiments in atomic/molecular optics (AMO). These analogies are made through the Hamiltonian and density operator formalism of angular momentum dynamics in the presence of electric and magnetic fields.The sixth chapter investigates the use of the macroscopic nuclear dipolar field to encode the NMR spectrum of an analyte nucleus indirectly in the magnetization of a sensor nucleus. This technique could potentially serve as an

  16. EASY-GOING deconvolution: Combining accurate simulation and evolutionary algorithms for fast deconvolution of solid-state quadrupolar NMR spectra

    NASA Astrophysics Data System (ADS)

    Grimminck, Dennis L. A. G.; Polman, Ben J. W.; Kentgens, Arno P. M.; Leo Meerts, W.

    2011-08-01

    A fast and accurate fit program is presented for deconvolution of one-dimensional solid-state quadrupolar NMR spectra of powdered materials. Computational costs of the synthesis of theoretical spectra are reduced by the use of libraries containing simulated time/frequency domain data. These libraries are calculated once and with the use of second-party simulation software readily available in the NMR community, to ensure a maximum flexibility and accuracy with respect to experimental conditions. EASY-GOING deconvolution ( EGdeconv) is equipped with evolutionary algorithms that provide robust many-parameter fitting and offers efficient parallellised computing. The program supports quantification of relative chemical site abundances and (dis)order in the solid-state by incorporation of (extended) Czjzek and order parameter models. To illustrate EGdeconv's current capabilities, we provide three case studies. Given the program's simple concept it allows a straightforward extension to include other NMR interactions. The program is available as is for 64-bit Linux operating systems.

  17. Directed Transformation from Quadrupolar to Dipolar Nematic Colloids by an In-Plane Electric Field

    NASA Astrophysics Data System (ADS)

    Tagashira, Kenji; Asakura, Keita; Yoshida, Hiroyuki; Ozaki, Masanori

    2013-02-01

    We demonstrate direction-controlled transformation from quadrupolar to dipolar nematic colloids using an in-plane electric field. When the electric field is applied in the direction perpendicular to the rubbing direction, a splay-bend wall is induced, which traps colloidal particles. Above the applied electric field of 0.14 V/µm, a Saturn-ring defect shrinks into a hedgehog defect due to the symmetric reorientation of the liquid crystal molecules around the particle. The direction of the shrinking is determined by the pretilt angle of the liquid crystal and the field direction near the edge of the electrode.

  18. From crystalline to glassy gallium fluoride materials: an NMR study of 69Ga and 71Ga quadrupolar nuclei.

    PubMed

    Bureau, B; Silly, G; Buzaré, J Y; Legein, C; Massiot, D

    1999-11-01

    Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of 69Ga and 71Ga are obtained in crystallised (PbGaF5, Pb3Ga2F12, Pb9Ga2F24 and CsZnGaF6) and glassy (PbF2-ZnF2-GaF3) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain consistent determinations of isotropic chemical shifts and very large quadrupolar parameters (nuQ up to 14 MHz). In the crystalline compounds whose structures are unknown, the number and the local symmetry of the different gallium sites are tentatively worked out. For the glassy systems, a continuous Czjzek's distribution of the NMR quadrupolar parameters accounts for the particular shape of the NMR spectrum. PMID:10670905

  19. From crystalline to glassy gallium fluoride materials: an NMR study of 69Ga and 71Ga quadrupolar nuclei.

    PubMed

    Bureau, B; Silly, G; Buzaré, J Y; Legein, C; Massiot, D

    1999-09-01

    Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of 69Ga and 71Ga are obtained in crystallised (PbGaF5, Pb3Ga2F12, Pb9Ga2F24 and CsZnGaF6) and glassy (PbF2-ZnF2-GaF3) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain consistent determinations of isotropic chemical shifts and very large quadrupolar parameters (nu(Q) up to 14 MHz). In the crystalline compounds whose structures are unknown, the number and the local symmetry of the different gallium sites are tentatively worked out. For the glassy systems, a continuous Czjzek's distribution of the NMR quadrupolar parameters accounts for the particular shape of the NMR spectrum. PMID:10499664

  20. Off-resonance effects on 2D NMR nutation spectra of I = 3/2 quadrupolar nuclei in static samples.

    PubMed

    Xia, Y; Deng, F; Ye, C

    1995-12-01

    The off-resonance effects on 2D NMR nutation of I = 3/2 quadrupolar nuclei are demonstrated with perturbation theory and numerical calculation in static samples. The off-resonant (delta omega) rf field (omega 1) enlarges a nutation frequency and consequently increases the measurement range of nuclear quadrupolar interaction parameters. When omega e > omega Qmax, and arctg(omega 1/delta omega) = +/- 54.7 degrees (magic angle), the satellite lines (produced by coherence transfers) in a nutation spectrum are superimposed with the line of central transition, and hence the nutation spectrum is simplified and its sensitivity is enhanced. The nuclear quadrupolar interaction parameters of 23Na nuclei in Na omega molecular sieve are obtained using 2D NMR nutation. PMID:9053113

  1. Space-fractional Schrödinger equation for a quadrupolar triple Dirac-δ potential: Central Dirac-δ well and barrier cases

    NASA Astrophysics Data System (ADS)

    Tare, Jeffrey D.; Esguerra, Jose Perico H.

    2015-01-01

    We solve the space-fractional Schrödinger equation for a quadrupolar triple Dirac-δ (QTD-δ) potential for all energies using the momentum-space approach. For the E < 0 solution, we consider two cases, i.e., when the strengths of the potential are V0 > 0 (QTD-δ potential with central Dirac-δ well) and V0 < 0 (QTD-δ potential with central Dirac-δ barrier) and derive expressions satisfied by the bound-state energy. For all fractional orders α considered, we find that there is one eigenenergy when V0 > 0, and there are two eigenenergies when V0 < 0. We also obtain both bound- and scattering-state (E > 0) wave functions and express them in terms of Fox's H-function.

  2. Molecular engineering of nanoscale quadrupolar chromophores for two-photon absorption

    NASA Astrophysics Data System (ADS)

    Porres, Laurent; Mongin, Olivier; Blanchard-Desce, Mireille H.; Ventelon, Lionel; Barzoukas, Marguerite; Moreaux, Laurent; Pons, Thomas; Mertz, Jerome

    2003-02-01

    Our aim has been the design of optimized NLO-phores with very high two-photon absorption (TPA) cross-sections (s2) in the red-NIR region, while maintaining high linear transparency and high fluorescence quantum yield. Our molecular engineering strategy is based on the push-push or pull-pull functionalization of semi-rigid nanoscale conjugated systems. The central building blocks were selected as rigid units that may assist quadrupolar intramolecular charge transfer by acting either as a (weak) donor or acceptor core. Quadrupolar molecules derived either from a phenyl unit, a rigidified biphenyl moiety or a fused bithiophene unit have been considered. Conjugated oligomers made of phenylene-vinylene and/or phenylene-ethynylene units were selected as connecting spacers between the core and the electroactive end groups to ensure effective electronic conjugation while maintaining suitable transparency/fluorescence. The TPA cross-sections were determined by investigating the two-photon-excited fluorescence properties using a Ti:sapphire laser delivering fs pulses. Both the nature of the end groups and of the core moiety play an important role in determining the TPA spectra. In addition, by adjusting the length and nature of the conjugated extensor, both amplification and spectral tuning of TPA cross-sections can be achieved. As a result, push-push fluorophores which demonstrate giant TPA cross-sections (up to 3000 GM) in the visible red, high fluorescence quantum yields and good transparency in the visible range have been obtained.

  3. A NON-RADIAL ERUPTION IN A QUADRUPOLAR MAGNETIC CONFIGURATION WITH A CORONAL NULL

    SciTech Connect

    Sun Xudong; Hoeksema, J. Todd; Liu Yang; Hayashi, Keiji; Chen Qingrong

    2012-10-01

    We report one of the several homologous non-radial eruptions from NOAA active region (AR) 11158 that are strongly modulated by the local magnetic field as observed with the Solar Dynamic Observatory. A small bipole emerged in the sunspot complex and subsequently created a quadrupolar flux system. Nonlinear force-free field extrapolation from vector magnetograms reveals its energetic nature: the fast-shearing bipole accumulated {approx}2 Multiplication-Sign 10{sup 31} erg free energy (10% of AR total) over just one day despite its relatively small magnetic flux (5% of AR total). During the eruption, the ejected plasma followed a highly inclined trajectory, over 60 Degree-Sign with respect to the radial direction, forming a jet-like, inverted-Y-shaped structure in its wake. Field extrapolation suggests complicated magnetic connectivity with a coronal null point, which is favorable of reconnection between different flux components in the quadrupolar system. Indeed, multiple pairs of flare ribbons brightened simultaneously, and coronal reconnection signatures appeared near the inferred null. Part of the magnetic setting resembles that of a blowout-type jet; the observed inverted-Y structure likely outlines the open field lines along the separatrix surface. Owing to the asymmetrical photospheric flux distribution, the confining magnetic pressure decreases much faster horizontally than upward. This special field geometry likely guided the non-radial eruption during its initial stage.

  4. Spin-glass state and magnetic-field-induced phenomena in distorted Eu{sub 0.58}Sr{sub 0.42}MnO{sub 3} perovskite

    SciTech Connect

    Sundaresan, A.; Maignan, A.; Raveau, B.

    1997-03-01

    Magnetic and magnetoresistance measurements were carried out on a distorted perovskite, Eu{sub 0.58}Sr{sub 0.42}MnO{sub 3}. In the absence of applied magnetic field, this compound is an insulator down to 5 K. Results of the ac- and dc-susceptibility measurements suggest a spin-glass ground state. An applied field of 7 T drives the insulator ground state to a ferromagnetic metallic state below T{sub C}=120 K. For a range of intermediate fields, the compound undergoes insulator-metal-insulator transitions which resemble those of 1:1 Mn{sup 3+}/Mn{sup 4+} charge-ordered compounds. A temperature-field phase diagram is established which depicts different magnetic and electronic states. {copyright} {ital 1997} {ital The American Physical Society}

  5. Signal enhancement of J-HMQC experiments in solid-state NMR involving half-integer quadrupolar nuclei.

    PubMed

    Wang, Qiang; Trébosc, Julien; Li, Yixuan; Xu, Jun; Hu, Bingwen; Feng, Ningdong; Chen, Qun; Lafon, Oliver; Amoureux, Jean-Paul; Deng, Feng

    2013-07-28

    We show that for half-integer quadrupolar nuclei, the manipulation of the satellite transitions can accelerate and enhance coherence transfer to other isotopes. This novel strategy is demonstrated to improve the sensitivity of (31)P-{(27)Al} J-HMQC experiments for a layered aluminophosphate Mu-4. PMID:23770976

  6. Quantum simulation of interaction blockade in a two-site Bose-Hubbard system with solid quadrupolar crystal

    NASA Astrophysics Data System (ADS)

    Nie, Xinfang; Li, Jun; Cui, Jiangyu; Luo, Zhihuang; Huang, Jiahao; Chen, Hongwei; Lee, Chaohong; Peng, Xinhua; Du, Jiangfeng

    2015-05-01

    The Bose-Hubbard model provides an excellent platform for exploring exotic quantum coherence. Interaction blockade is an important fundamental phenomenon in the two-site Bose-Hubbard system (BHS), which gives a full quantum description for the atomic Bose-Josephson junction. Using the analogy between the two-site BHS and the quadrupolar nuclear magnetic resonance (NMR) crystal, we experimentally simulate a two-site Bose-Hubbard system in a NMR quantum simulator composed of the quadrupolar spin-3/2 sodium nuclei of a NaNO3 single crystal, and observe the interesting phenomenon of interaction blockade via adiabatic dynamics control. To our best knowledge, this is the first experimental implementation of the quantum simulation of the interaction blockade using quadrupolar nuclear system. Our work exhibits important applications of quadrupolar NMR in the quantum information science, i.e. a spin-3/2 system can be used as a full 2-qubit su(4) system, if the quadrupole moment is not fully averaged out by fast tumbling in the liquid phase.

  7. Alkaline earth chloride hydrates: chlorine quadrupolar and chemical shift tensors by solid-state NMR spectroscopy and plane wave pseudopotential calculations.

    PubMed

    Bryce, David L; Bultz, Elijah B

    2007-01-01

    A series of alkaline earth chloride hydrates has been studied by solid-state (35/37)Cl NMR spectroscopy in order to characterize the chlorine electric field gradient (EFG) and chemical shift (CS) tensors and to relate these observables to the structure around the chloride ions. Chlorine-35/37 NMR spectra of solid powdered samples of pseudopolymorphs (hydrates) of magnesium chloride (MgCl(2).6H(2)O), calcium chloride (CaCl(2).2H(2)O), strontium chloride (SrCl(2), SrCl(2).2H(2)O, and SrCl(2).6H(2)O), and barium chloride (BaCl(2).2H(2)O) have been acquired under stationary and magic-angle spinning conditions in magnetic fields of 11.75 and 21.1 T. Powder X-ray diffraction was used as an additional tool to confirm the purity and identity of the samples. Chlorine-35 quadrupolar coupling constants (C(Q)) range from essentially zero in cubic anhydrous SrCl(2) to 4.26+/-0.03 MHz in calcium chloride dihydrate. CS tensor spans, Omega, are between 40 and 72 ppm, for example, Omega= 45+/-20 ppm for SrCl(2).6H(2)O. Plane wave-pseudopotential density functional theory, as implemented in the CASTEP program, was employed to model the extended solid lattices of these materials for the calculation of their chlorine EFG and nuclear magnetic shielding tensors, and allowed for the assignment of the two-site chlorine NMR spectra of barium chloride dihydrate. This work builds upon our current understanding of the relationship between chlorine NMR interaction tensors and the local molecular and electronic structure, and highlights the particular sensitivity of quadrupolar nucleus solid-state NMR spectroscopy to the differences between various pseudopolymorphic structures in the case of strontium chloride. PMID:17385204

  8. From bipolar to quadrupolar - The collimation processes of the Cepheus A outflow

    NASA Technical Reports Server (NTRS)

    Torrelles, Jose M.; Verdes-Montenegro, Lourdes; Ho, Paul T. P.; Rodriguez, Luis F.; Canto, Jorge

    1993-01-01

    Results of new K-band observations of the (1, 1) and (2, 2) ammonia lines toward Cepheus A are reported. The lines are mapped with approximately 2 arcsec of angular resolution and 0.3 km/s of velocity resolution. A sensitivity of 10 mJy has been achieved. The observations reveal details of the spatial and kinematics structure of the ambient high-density gas. It is suggested that the interstellar high-density gas is diverting and redirecting the outflow in the sense that the quadrupolar structure of the molecular outflow is produced by the interaction with the ammonia condensationss, with Cep A-1 and Cep A-3 splitting in two halves, respectively the blue- and redshifted lobes of an east-west bipolar molecular outflow.

  9. Bis-pyridinium quadrupolar derivatives. High Stokes shift selective probes for bio-imaging

    NASA Astrophysics Data System (ADS)

    Salice, Patrizio; Versari, Silvia; Bradamante, Silvia; Meinardi, Francesco; Macchi, Giorgio; Pagani, Giorgio A.; Beverina, Luca

    2013-11-01

    We describe the design, synthesis and characterization of five high Stokes shift quadrupolar heteroaryl compounds suitable as fluorescent probes in bio-imaging. In particular, we characterize the photophysical properties and the intracellular localization in Human Umbilical Vein Endothelial Cells (HUVEC) and Human Mesenchymal Stem Cells (HMSCs) for each dye. We show that, amongst all of the investigated derivatives, the 2,5-bis[1-(4-N-methylpyridinium)ethen-2-yl)]- N-methylpyrrole salt is the best candidates as selective mitochondrial tracker. Finally, we recorded the full emission spectrum of the most performing - exclusively mitochondrial selective - fluorescent probe directly from HUVEC stained cells. The emission spectrum collected from the stained mitochondria shows a remarkably more pronounced vibronic structure with respect to the emission of the free fluorophore in solution.

  10. Method to determine the optimal layer number for the quadrupolar fiber coil

    NASA Astrophysics Data System (ADS)

    Gao, Zhongxing; Zhang, Yonggang; Gao, Wei

    2014-08-01

    For a high precision interferometric fiber optic gyroscope (IFOG) under temperature control, a short start-up time and small temperature drift are important for its applications. The start-up time and the temperature drift of IFOG with the same fiber length but with a different fiber coil layer number are investigated and compared. Simulation by finite difference time domain method is done to illustrate the existence of optimal layer number for the fiber coil wound by the quadrupolar method. Theoretical analysis is then provided and a closed-form formulation is given to calculate the optimal layer number of the fiber coil, which can effectively reduce both the start-up time and temperature drift of IFOG. Our study is meaningful in improving the thermal performance of the fiber coil.

  11. Radiofrequency quadrupolar NMR stark spectroscopy: steady state response calibration and tensorial mapping.

    PubMed

    Tarasek, Matthew R; Kempf, James G

    2010-10-01

    Radiofrequency electric (E) fields oscillating at twice the usual NMR frequency (2ω(0)) can induce double-quantum transitions in quadrupolar nuclei, an NMR Stark effect. Characterization of such is of interest to aid understanding of electrostatic effects in NMR spectra. Calibration of Stark responses to an applied electric field may also be used to assess native fields within molecules and materials. We present high-field (14.1 T), room-temperature NMR experiments to calibrate the 2ω(0) Stark response in crystalline GaAs. This system presents an important test of current techniques and conditions, as historical studies at low field (500-900 mT) and low temperature (77 K) provide a basis for comparison. Our measurements of steady state response reveal the quadrupolar Stark tuning rate for (69)Ga in this material. The value, β(Q) = (11.5 ± 0.1) × 10(12) m(-1), is 3.6 times larger than the most-reliable prior result. In the process, we also uncovered a previously unobserved double-quantum steady state coherence. It appears as a completely separable dispersive signal component in quadrature-detected presaturation spectra versus offset from 2ω(0). The new component may eventually afford an independent route to calibrating β(Q). Finally, we demonstrated exceptional agreement with theory of the orientation-dependent Stark response for rotation of the sample relative to B(0) over a range of 90° and for E-field amplitudes from 30-180 V/cm. PMID:20839890

  12. Magnetic field induced differential neutron phase contrast imaging

    SciTech Connect

    Strobl, M.; Treimer, W.; Walter, P.; Keil, S.; Manke, I.

    2007-12-17

    Besides the attenuation of a neutron beam penetrating an object, induced phase changes have been utilized to provide contrast in neutron and x-ray imaging. In analogy to differential phase contrast imaging of bulk samples, the refraction of neutrons by magnetic fields yields image contrast. Here, it will be reported how double crystal setups can provide quantitative tomographic images of magnetic fields. The use of magnetic air prisms adequate to split the neutron spin states enables a distinction of field induced phase shifts and these introduced by interaction with matter.

  13. Magnetic field induced minigap in double quantum wells

    SciTech Connect

    Simmons, J.A.; Lyo, S.K.; Klem, J.F.; Harff, N.E. |

    1994-07-01

    We report discovery of a partial energy gap, or minigap, in strongly coupled double quantum wells (QWs), due to an anticrossing of the two QW dispersion curves. The anticrossing and minigap are induced by an in-plane magnetic field B{sub {parallel}}, and give rise to large distortions in the Fermi surface and density of states, including a Van Hove singularity. Sweeping B{sub {parallel}} moves the minigap through the Fermi level, with the upper and lower gap edges producing a sharp maximum and minimum in the low-temperature in-plane conductance, in agreement with theoretical calculations. The gap energy may be directly determined from the data.

  14. Strong Magnetic Field Induced Changes of Gene Expression in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Paul, A.-L.; Ferl, R. J.; Klingenberg, B.; Brooks, J. S.; Morgan, A. N.; Yowtak, J.; Meisel, M. W.

    2005-07-01

    We review our studies of the biological impact of magnetic field strengths of up to 30 T on transgenic arabidopsis plants engineered with a stress response gene consisting of the alcohol dehydrogenase (Adh) gene promoter driving the β-glucuronidase (GUS) gene reporter. Field strengths in excess of 15 T induce expression of the Adh/GUS transgene in the roots and leaves. Microarray analyses indicate that such field strengths have a far reaching effect on the genome. Wide spread induction of stress-related genes and transcription factors, and a depression of genes associated with cell wall metabolism are prominent examples.

  15. High magnetic field induced otolith fusion in the zebrafish larvae.

    PubMed

    Pais-Roldán, Patricia; Singh, Ajeet Pratap; Schulz, Hildegard; Yu, Xin

    2016-01-01

    Magnetoreception in animals illustrates the interaction of biological systems with the geomagnetic field (geoMF). However, there are few studies that identified the impact of high magnetic field (MF) exposure from Magnetic Resonance Imaging (MRI) scanners (>100,000 times of geoMF) on specific biological targets. Here, we investigated the effects of a 14 Tesla MRI scanner on zebrafish larvae. All zebrafish larvae aligned parallel to the B0 field, i.e. the static MF, in the MRI scanner. The two otoliths (ear stones) in the otic vesicles of zebrafish larvae older than 24 hours post fertilization (hpf) fused together after the high MF exposure as short as 2 hours, yielding a single-otolith phenotype with aberrant swimming behavior. The otolith fusion was blocked in zebrafish larvae under anesthesia or embedded in agarose. Hair cells may play an important role on the MF-induced otolith fusion. This work provided direct evidence to show that high MF interacts with the otic vesicle of zebrafish larvae and causes otolith fusion in an "all-or-none" manner. The MF-induced otolith fusion may facilitate the searching for MF sensors using genetically amenable vertebrate animal models, such as zebrafish. PMID:27063288

  16. Magnetic-field-induced localization in 2D topological insulators.

    PubMed

    Delplace, Pierre; Li, Jian; Büttiker, Markus

    2012-12-14

    Localization of the helical edge states in quantum spin Hall insulators requires breaking time-reversal invariance. In experiments, this is naturally implemented by applying a weak magnetic field B. We propose a model based on scattering theory that describes the localization of helical edge states due to coupling to random magnetic fluxes. We find that the localization length is proportional to B^{-2} when B is small and saturates to a constant when B is sufficiently large. We estimate especially the localization length for the HgTe/CdTe quantum wells with known experimental parameters. PMID:23368362

  17. Magnetic Field Induced Changes Of Domain Structure Grating.

    NASA Astrophysics Data System (ADS)

    Maziewski, A.; Stankiewicz, A.

    1987-10-01

    A stripe domain grating (SDG) has been theoretically analysed to combine some magnetic field changeable grating parameters with a magnetic sample material parameters. The alterable grating properties were discussed for different types of fiber-optic switch device. The quality and prefered directions of SDG have been quantitatively investigated using unconventional set-up based on the light diffraction effect. The gratings have been induced by the magnetic field with different orientations and values. SDG quality was significantly improved applying nontypically oriented magnetic field. We focused our attention on SDG static properties.

  18. Temporally-Patterned Magnetic Fields Induce Complete Fragmentation in Planaria

    PubMed Central

    Murugan, Nirosha J.; Karbowski, Lukasz M.; Lafrenie, Robert M.; Persinger, Michael A.

    2013-01-01

    A tandem sequence composed of weak temporally-patterned magnetic fields was discovered that produced 100% dissolution of planarian in their home environment. After five consecutive days of 6.5 hr exposure to a frequency-modulated magnetic field (0.1 to 2 µT), immediately followed by an additional 6.5 hr exposure on the fifth day, to another complex field (0.5 to 5 µT) with exponentially increasing spectral power 100% of planarian dissolved within 24 hr. Reversal of the sequence of the fields or presentation of only one pattern for the same duration did not produce this effect. Direct video evidence showed expansion (by visual estimation ∼twice normal volume) of the planarian following the first field pattern followed by size reduction (estimated ∼1/2 of normal volume) and death upon activation of the second pattern. The contortions displayed by the planarian during the last field exposure suggest effects on contractile proteins and alterations in the cell membrane’s permeability to water. PMID:23620783

  19. Magnetic field induced spin-wave energy focusing

    NASA Astrophysics Data System (ADS)

    Perez, Noel; Lopez-Diaz, Luis

    2015-07-01

    Local temperature variations induced by spin-wave propagation are studied using a model that couples nonuniform magnetization dynamics and heat flow. We show that the remote heating at the sample edge reported recently [T. An et al., Nat. Mater. 12, 549 (2013)], 10.1038/nmat3628 is due to the geometry-induced gradual reduction of the effective field. We demonstrate that the same effect can be achieved by a reduction in the external field instead of a constriction at the edge and, furthermore, that both the location and the amount of energy to be delivered to the lattice can be controlled accurately this way.

  20. High magnetic field induced otolith fusion in the zebrafish larvae

    PubMed Central

    Pais-Roldán, Patricia; Singh, Ajeet Pratap; Schulz, Hildegard; Yu, Xin

    2016-01-01

    Magnetoreception in animals illustrates the interaction of biological systems with the geomagnetic field (geoMF). However, there are few studies that identified the impact of high magnetic field (MF) exposure from Magnetic Resonance Imaging (MRI) scanners (>100,000 times of geoMF) on specific biological targets. Here, we investigated the effects of a 14 Tesla MRI scanner on zebrafish larvae. All zebrafish larvae aligned parallel to the B0 field, i.e. the static MF, in the MRI scanner. The two otoliths (ear stones) in the otic vesicles of zebrafish larvae older than 24 hours post fertilization (hpf) fused together after the high MF exposure as short as 2 hours, yielding a single-otolith phenotype with aberrant swimming behavior. The otolith fusion was blocked in zebrafish larvae under anesthesia or embedded in agarose. Hair cells may play an important role on the MF-induced otolith fusion. This work provided direct evidence to show that high MF interacts with the otic vesicle of zebrafish larvae and causes otolith fusion in an “all-or-none” manner. The MF-induced otolith fusion may facilitate the searching for MF sensors using genetically amenable vertebrate animal models, such as zebrafish. PMID:27063288

  1. Strain enhanced charge order melting in Pr0.5Ca0.5MnO3 thin films

    NASA Astrophysics Data System (ADS)

    Baisnab, Dipak Kumar; Kumary, T. Geetha; Satya, A. T.; Mani, Awadhesh; Janaki, J.; Nithya, R.; Vaidhyanathan, L. S.; Janawadkar, M. P.; Bharathi, A.

    2011-06-01

    The effect of strain on charge order melting in half doped manganite Pr0.5Ca0.5MnO3 thin films of different thicknesses has been investigated. The films were deposited on (100) oriented MgO substrates by pulsed laser deposition technique and were characterized by x-ray diffraction, electrical resistivity and magnetoresistance measurements. A field induced charge order melting is observed for films with very small thickness. The charge order transition temperature and the magnetic field induced charge order melting appears to be governed by the nature of strain that is experienced by the film.

  2. NMR of group 2 element quadrupolar nuclei and some applications in materials science and biology

    NASA Astrophysics Data System (ADS)

    Li, Xiaohua

    1999-11-01

    For many years, NMR has provided an easy access for chemists to perform structural and kinetic studies on a whole variety of systems. To a great extent, these investigations have been restricted to non-quadrupolar nuclei. The study of quadrupolar nuclei (I > 1/2) offers the potential to gain insight into important problems in material science and biology. In addition to the large quadrupole moment associated with the spin active nuclei of interest, several of the most interesting species also possess an extremely low natural abundance. My recent research focuses on 87Sr NMR, which has been cited by earlier workers as being limited to only ionic species. Several strontium-containing compounds have been synthesized and characterized by single crystal x-ray diffraction. 87Sr NMR signals were determined for these compounds in a series of aprotic polar solvents. The chemical shift variation was found to be consistent with linen free energy relationship, which can be very useful in helping to elucidate mechanism, in predicting reaction rates, and the extent of reaction at equilibrium, and in discovering under what conditions a change in mechanism occurs. Control over symmetry of the compound was found to be the key to obtain the good NMR signals. One application of the new technique that has been developed was in the area of material science. An observation relative to sol-gel derived ionic conductors (La0.8Sr0.2Co0.8Fe0.2O 3.2) was that films often formed cracks upon pyrolysis. By careful examination of the sol-gel process by 87Sr NMR, a model for the structure of the sol was developed. Through the relaxation rate study of the strontium sites, the polymerization mechanism was determined to be predominantly bimolecular within the concentration region studied. The kinetic study of the fast cation exchange between two strontium sites indicated that the inhomogeneity of the polymeric network lads to the film cracking during pyrolysis. As a consequence of understanding the

  3. Two-Photon Absorption and Fluorescence with Quadrupolar and Branched CHROMOPHORES—EFFECT of Structure and Branching

    NASA Astrophysics Data System (ADS)

    Porrès, Laurent; Mongin, Olivier; Katan, Claudine; Charlot, Marina; Bhatthula, Bharath Kumar Goud; Jouikov, Viatcheslav; Pons, Thomas; Mertz, Jerome; Blanchard-Desce, Mireille

    The photophysical and two-photon absorption (TPA) properties of three homologous quadrupolar and one related three-branched chromophores were investigated. Design of the quadrupoles is based on the symmetrical functionalization of a biphenyl core. Modulation of the nonlinear absorptivity/transparency/photostability trade-off can be achieved by playing with the twist angle of the core and on the spacers (phenylene-vinylene versus phenylene-ethynylene). The quadrupolar chromophores combine high TPA cross-sections, high fluorescence quantum yield and solvent sensitive photoluminescence properties. The branched structure exhibits spectrally broadened TPA in the NIR region (up to 3660 GM at 740 nm measured in the femtosecond regime) but reduced sensitivity to the environment.

  4. Population and coherence transfer induced by double frequency sweeps in half-integer quadrupolar spin systems.

    PubMed

    Iuga, D; Schäfer, H; Verhagen, R; Kentgens, A P

    2000-12-01

    We have recently shown that the sensitivity of single- and multiple-quantum NMR experiments of half-integer (N/2) quadrupolar nuclei can be increased significantly by introducing so-called double frequency sweeps (DFS) in various pulse schemes. These sweeps consist of two sidebands generated by an amplitude modulation of the RF carrier. Using a time-dependent amplitude modulation the sidebands can be swept through a certain frequency range. Inspired by the work of Vega and Naor (J. Chem. Phys. 75, 75 (1981)), this is used to manipulate +/-(m - 1) <--> +/-m (3/2 < or = m < or = N/2) satellite transitions in half-integer spin systems simultaneously. For (23)Na (I = 3/2) and (27)Al (I = 5/2) spins in single crystals it proved possible to transfer the populations of the outer +/-m spin levels to the inner +/-1/2 spin levels. A detailed analysis shows that the efficiency of this process is a function of the adiabaticity with which the various spin transitions are passed during the sweep. In powders these sweep parameters have to be optimized to satisfy the appropriate conditions for a maximum of spins in the powder distribution. The effects of sweep rate, sweep range, and RF field strength are investigated both numerically and experimentally. Using a DFS as a preparation period leads to significantly enhanced central transition powder spectra under both static and MAS conditions, compared to single pulse excitation. DFSs prove to be very efficient tools not only for population transfer, but also for coherence transfer. This can be exploited for the multiple- to single-quantum transfer in MQMAS experiments. It is demonstrated, theoretically and experimentally, that DFSs are capable of transferring both quintuple-quantum and triple-quantum coherence into single-quantum coherence in I = 5/2 spin systems. This leads to a significant enhancement in signal-to-noise ratio and strongly reduces the RF power requirement compared to pulsed MQMAS experiments, thus extending their

  5. In vivo observation of quadrupolar splitting in (39)K magnetic resonance spectroscopy of human muscle tissue.

    PubMed

    Rösler, M B; Nagel, A M; Umathum, R; Bachert, P; Benkhedah, N

    2016-04-01

    The purpose of this work was to explore the origin of oscillations of the T(*)2 decay curve of (39)K observed in studies of (39)K magnetic resonance imaging of the human thigh. In addition to their magnetic dipole moment, spin-3/2 nuclei possess an electric quadrupole moment. Its interaction with non-vanishing electrical field gradients leads to oscillations in the free induction decay and to splitting of the resonance. All measurements were performed on a 7T whole-body MRI scanner (MAGNETOM 7T, Siemens AG, Erlangen, Germany) with customer-built coils. According to the theory of quadrupolar splitting, a model with three Lorentzian-shaped peaks is appropriate for (39)K NMR spectra of the thigh and calf. The frequency shifts of the satellites depend on the angle between the calf and the static magnetic field. When the leg is oriented parallel to the static magnetic field, the satellites are shifted by about 200 Hz. In the thigh, rank-2 double quantum coherences arising from anisotropic quadrupolar interaction are observed by double-quantum filtration with magic-angle excitation. In addition to the spectra, an image of the thigh with a nominal resolution of (16 × 16 × 32) mm(3) was acquired with this filtering technique in 1:17 h. From the line width of the resonances, (39)K transverse relaxation time constants T(*)2, fast  = (0.51 ± 0.01) ms and T(*)2, slow  = (6.21 ± 0.05) ms for the head were determined. In the thigh, the left and right satellite, both corresponding to the short component of the transverse relaxation time constant, take the following values: T(*)2, fast  = (1.56 ± 0.03) ms and T(*)2, fast  = (1.42 ± 0.03) ms. The centre line, which corresponds to the slow component, is T(*)2, slow  = (9.67 ± 0.04) ms. The acquisition time of the spectra was approximately 10 min. Our results agree well with a non-vanishing electrical field gradient interacting with (39)K nuclei in the intracellular space of

  6. Magnetic alignment and quadrupolar/paramagnetic cross-correlation in complexes of Na with LnDOTP5-

    NASA Astrophysics Data System (ADS)

    Eliav, Uzi; Chandra shekar, S.; Ling, Wen; Navon, Gil; Jerschow, Alexej

    2012-03-01

    The observation of a double-quantum filtered signal of quadrupolar nuclei (e.g. 23Na) in solution has been traditionally interpreted as a sign for anisotropic reorientational motion. Ling and Jerschow (2007) [23] have found that a 23Na double-quantum signal is observed also in solutions of TmDOTPNa5. Interference effects between the quadrupolar and the paramagnetic interactions have been reported to lead to the appearance of double-quantum coherences even in the absence of a residual quadrupolar interaction. In addition, such processes lead to differential linebroadening effects between the satellite transitions, akin to effects that are well known for dipolar-CSA cross-correlation. Here, we report experiments on sodium in the presence of LnDOTP compounds, where it is shown that these cross-correlation effects correlate well with the pseudo-contact shift. In addition, anisotropic g-values of the lanthanide compounds in question, can also lead to alignment within the magnetic field, and consequently to the appearance of line splitting and double-quantum coherences. The two competing effects are demonstrated and it is concluded that both cross-correlated relaxation and alignment in the magnetic field must be at work in the systems described here.

  7. SIMPRE1.2: Considering the hyperfine and quadrupolar couplings and the nuclear spin bath decoherence.

    PubMed

    Cardona-Serra, Salvador; Escalera-Moreno, Luis; Baldoví, José J; Gaita-Ariño, Alejandro; Clemente-Juan, Juan M; Coronado, Eugenio

    2016-05-15

    SIMPRE is a fortran77 code which uses an effective electrostatic model of point charges to predict the magnetic behavior of rare-earth-based mononuclear complexes. In this article, we present SIMPRE1.2, which now takes into account two further phenomena. First, SIMPRE now considers the hyperfine and quadrupolar interactions within the rare-earth ion, resulting in a more complete and realistic set of energy levels and wave functions. Second, and to widen SIMPRE's predictive capabilities regarding potential molecular spin qubits, it now includes a routine that calculates an upper-bound estimate of the decoherence time considering only the dipolar coupling between the electron spin and the surrounding nuclear spin bath. Additionally, SIMPRE now allows the user to introduce the crystal field parameters manually. Thus, we are able to demonstrate the new features using as examples (i) a Gd-based mononuclear complex known for its properties both as a single ion magnet and as a coherent qubit and (ii) an Er-based mononuclear complex. © 2016 Wiley Periodicals, Inc. PMID:26833799

  8. Modeling for IFOG Vibration Error Based on the Strain Distribution of Quadrupolar Fiber Coil

    PubMed Central

    Gao, Zhongxing; Zhang, Yonggang; Zhang, Yunhao

    2016-01-01

    Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environment, especially in vibrational environment, is necessary for its practical applications. This paper presents a mathematical model for IFOG to theoretically compute the short-term rate errors caused by mechanical vibration. The computational procedures are mainly based on the strain distribution of quadrupolar fiber coil measured by stress analyzer. The definition of asymmetry of strain distribution (ASD) is given in the paper to evaluate the winding quality of the coil. The established model reveals that the high ASD and the variable fiber elastic modulus in large strain situation are two dominant reasons that give rise to nonreciprocity phase shift in IFOG under vibration. Furthermore, theoretical analysis and computational results indicate that vibration errors of both open-loop and closed-loop IFOG increase with the raise of vibrational amplitude, vibrational frequency and ASD. Finally, an estimation of vibration-induced IFOG errors in aircraft is done according to the proposed model. Our work is meaningful in designing IFOG coils to achieve a better anti-vibration performance. PMID:27455257

  9. Modeling for IFOG Vibration Error Based on the Strain Distribution of Quadrupolar Fiber Coil.

    PubMed

    Gao, Zhongxing; Zhang, Yonggang; Zhang, Yunhao

    2016-01-01

    Improving the performance of interferometric fiber optic gyroscope (IFOG) in harsh environment, especially in vibrational environment, is necessary for its practical applications. This paper presents a mathematical model for IFOG to theoretically compute the short-term rate errors caused by mechanical vibration. The computational procedures are mainly based on the strain distribution of quadrupolar fiber coil measured by stress analyzer. The definition of asymmetry of strain distribution (ASD) is given in the paper to evaluate the winding quality of the coil. The established model reveals that the high ASD and the variable fiber elastic modulus in large strain situation are two dominant reasons that give rise to nonreciprocity phase shift in IFOG under vibration. Furthermore, theoretical analysis and computational results indicate that vibration errors of both open-loop and closed-loop IFOG increase with the raise of vibrational amplitude, vibrational frequency and ASD. Finally, an estimation of vibration-induced IFOG errors in aircraft is done according to the proposed model. Our work is meaningful in designing IFOG coils to achieve a better anti-vibration performance. PMID:27455257

  10. Electrical Nuclear Quadrupolar Interaction of ZINC-67 in a Single Crystal of Zinc.

    NASA Astrophysics Data System (ADS)

    Goyette, Jacques

    The nuclear quadrupolar coupling of ('67)Zn in a single crystal of zinc has been studied using the techniques of nuclear acoustic resonance (NAR) and nuclear magnetic resonance (NMR) at low temperatures. NAR, which is an attractive way of doing resonance experiments, is analogous to NMR except in the fact that we use phonons instead of photons to induce transitions thereby avoiding the skin -depth problems met when we do NMR in single metallic crystal. While our NAR experiments were unfruitful mainly due to the large magnetoresistance effects shown by zinc at low temperatures, we were able to circumvent these problems in our NMR experiments by using a time-sharing spectrometer which did not require modulation of the magnetic field. This way, we studied the I(,z) = 1/2 to I(,z) = -1/2 magnetic resonance transition of the I = 5/2 ground state of ('67)Zn in a single crystal of zinc metal as a function of crystal orientation in a magnetic field of 72 kilogauss. The small frequency deviation versus crystal orientation has been used to evaluate the electric quadrupole interaction e('2)qQ/h as 12.19(2) Mhz, the isotropic Knight shift as 0.236(6)% and the anisotropic Knight shift as 0.013(2)% at 4.2(DEGREES)K.

  11. Formation of a White-Light Jet Within a Quadrupolar Magnetic Configuration

    NASA Astrophysics Data System (ADS)

    Filippov, Boris; Koutchmy, Serge; Tavabi, Ehsan

    2013-08-01

    We analyze multi-wavelength and multi-viewpoint observations of a large-scale event viewed on 7 April 2011, originating from an active-region complex. The activity leads to a white-light jet being formed in the outer corona. The topology and evolution of the coronal structures were imaged in high resolution using the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). In addition, large field-of-view images of the corona were obtained using the Sun Watcher using Active Pixel System detector and Image Processing (SWAP) telescope onboard the PRoject for Onboard Autonomy (PROBA2) microsatellite, providing evidence for the connectivity of the coronal structures with outer coronal features that were imaged with the Large Angle Spectrometric Coronagraph (LASCO) C2 on the S olar and Heliospheric Observatory (SOHO). The data sets reveal an Eiffel-tower type jet configuration extending into a narrow jet in the outer corona. The event starts from the growth of a dark area in the central part of the structure. The darkening was also observed in projection on the disk by the Solar TErrestrial RElations Observatory-Ahead (STEREO-A) spacecraft from a different point of view. We assume that the dark volume in the corona descends from a coronal cavity of a flux rope that moved up higher in the corona but still failed to erupt. The quadrupolar magnetic configuration corresponds to a saddle-like shape of the dark volume and provides a possibility for the plasma to escape along the open field lines into the outer corona, forming the white-light jet.

  12. On the microscopic fluctuations driving the NMR relaxation of quadrupolar ions in water

    SciTech Connect

    Carof, Antoine; Salanne, Mathieu; Rotenberg, Benjamin; Charpentier, Thibault

    2015-11-21

    Nuclear Magnetic Resonance (NMR) relaxation is sensitive to the local structure and dynamics around the probed nuclei. The Electric Field Gradient (EFG) is the key microscopic quantity to understand the NMR relaxation of quadrupolar ions, such as {sup 7}Li{sup +}, {sup 23}Na{sup +}, {sup 25}Mg{sup 2+}, {sup 35}Cl{sup −}, {sup 39}K{sup +}, or {sup 133}Cs{sup +}. Using molecular dynamics simulations, we investigate the statistical and dynamical properties of the EFG experienced by alkaline, alkaline Earth, and chloride ions at infinite dilution in water. Specifically, we analyze the effect of the ionic charge and size on the distribution of the EFG tensor and on the multi-step decay of its auto-correlation function. The main contribution to the NMR relaxation time arises from the slowest mode, with a characteristic time on the picosecond time scale. The first solvation shell of the ion plays a dominant role in the fluctuations of the EFG, all the more that the ion radius is small and its charge is large. We propose an analysis based on a simplified charge distribution around the ion, which demonstrates that the auto-correlation of the EFG, hence the NMR relaxation time, reflects primarily the collective translational motion of water molecules in the first solvation shell of the cations. Our findings provide a microscopic route to the quantitative interpretation of NMR relaxation measurements and open the way to the design of improved analytical theories for NMR relaxation for small ionic solutes, which should focus on water density fluctuations around the ion.

  13. Dynamic effects in MAS and MQMAS NMR spectra of half-integer quadrupolar nuclei: calculations and an application to the double perovskite cryolite.

    PubMed

    Kotecha, Mrignayani; Chaudhuri, Santanu; Grey, Clare P; Frydman, Lucio

    2005-11-30

    Dynamic processes such as chemical exchange or rotations between inequivalent orientations can affect the magic-angle spinning (MAS) and the multiple-quantum (MQ) MAS NMR spectra of half-integer quadrupolar nuclei. The present paper discusses such dynamic multisite MAS and MQMAS effects and applies them to study the dynamic processes that occur in the double perovskite cryolite, Na3AlF6. Dynamic line shape simulations invoking a second-order broadening of the central transition and relying on the semiclassical Bloch-McConnell formalism for chemical exchange were performed for a variety of exchange models possessing different symmetries. Fitting experimental variable-temperature cryolite 23Na NMR data with this formalism revealed that the two inequivalent sodium sites in this mineral undergo an exchange characterized by a broad distribution of rates. To further assess this dynamic process a variety of 27Al and 19F MAS NMR studies were also undertaken; quantitative 27Al-19F dipolar coupling measurements then revealed a dynamic motion of the AlF6 octahedra that were qualitatively consistent with predictions stemming from molecular dynamic simulations on this double perovskite. PMID:16305261

  14. DFT-D study of 14N nuclear quadrupolar interactions in tetra-n-alkyl ammonium halide crystals.

    PubMed

    Dib, Eddy; Alonso, Bruno; Mineva, Tzonka

    2014-05-15

    The density functional theory-based method with periodic boundary conditions and addition of a pair-wised empirical correction for the London dispersion energy (DFT-D) was used to study the NMR quadrupolar interaction (coupling constant CQ and asymmetry parameter ηQ) of (14)N nuclei in a homologous series of tetra-n-alkylammonium halides (C(x)H(2x+1))4N(+)X(-) (x = 1-4), (X = Br, I). These (14)N quadrupolar properties are particularly challenging for the DFT-D computations because of their very high sensitivity to tiny geometrical changes, being negligible for other spectral property calculations as, for example, NMR (14)N chemical shift. In addition, the polarization effect of the halide anions in the considered crystal mesophases combines with interactions of van der Waals type between cations and anions. Comparing experimental and theoretical results, the performance of PBE-D functional is preferred over that of B3LYP-D. The results demonstrated a good transferability of the empirical parameters in the London dispersion formula for crystals with two or more carbons per alkyl group in the cations, whereas the empirical corrections in the tetramethylammonium halides appeared to be inappropriate for the quadrupolar interaction calculation. This is attributed to the enhanced cation-anion attraction, which causes a strong polarization at the nitrogen site. Our results demonstrated that the (14)N CQ and ηQ are predominantly affected by the molecular structures of the cations, adapted to the symmetry of the anion arrangements. The long-range polarization effect of the surrounding anions at the target nitrogen site becomes more important for cells with lower spatial symmetry. PMID:24758512

  15. Evidence for ferroquadrupole order in YbRu2 Ge2 from x-ray diffraction and elastoresistivity measurements

    NASA Astrophysics Data System (ADS)

    Rosenberg, Elliott; Chu, Jiun-Haw; Fisher, Ian; Ruff, Jacob

    YbRu2Ge2 undergoes a non-magnetic phase transition at 10K, several Kelvin above a phase transition to a magnetically ordered state that is characterized by a unidirectional incommensurate spin density wave. Here, we show via high-resolution x-ray diffraction that the non-magnetic phase transition corresponds to a continuous tetragonal-to-orthorhombic structural phase transition. Elastoresistance measurements in the tetragonal state indicate a divergence of the quadrupolar strain susceptibility in the B1g symmetry channel, implying that the structural phase transition is driven by quadrupolar order.

  16. (39)K NMR of solid potassium salts at 21 T: effect of quadrupolar and chemical shift tensors.

    PubMed

    Moudrakovski, Igor L; Ripmeester, John A

    2007-01-25

    39K Solid State NMR spectra (static and magic angle spinning (MAS)) on a set of potassium salts measured at 21.14 T show that the chemical shift range for K(+) ions in diamagnetic salts is well in excess of 100 ppm contrary to previous assumptions that it was quite small. Inequivalent potassium sites in crystals can be resolved through differences in chemical shifts, with chemically similar sites showing differences of over 10 ppm. The quadrupolar coupling constants obtained from MAS and solid echo experiments on powders cover the range from zero for potassium in cubic environments in halides to over 3 MHz for the highly asymmetric sites in K2CO3. Although the quadrupolar effects generally dominate the 39K spectra, in several instances, we have observed subtle but significant contributions of chemical shift anisotropy with values up to 45 ppm, a first such observation. Careful analysis of static and MAS spectra allows the observation of the various chemical shift and quadrupole coupling tensor components as well as their relative orientations, thereby demonstrating that high-field 39K NMR spectroscopy in the solid state has a substantial sensitivity to the local environment with parameters that will be of considerable value in materials characterization and electronic structure studies. PMID:17228903

  17. Efficient rotational echo double resonance recoupling of a spin-1/2 and a quadrupolar spin at high spinning rates and weak irradiation fields

    NASA Astrophysics Data System (ADS)

    Nimerovsky, Evgeny; Goldbourt, Amir

    2010-09-01

    A modification of the rotational echo (adiabatic passage) double resonance experiments, which allows recoupling of the dipolar interaction between a spin-1/2 and a half integer quadrupolar spin is proposed. We demonstrate efficient and uniform recoupling at high spinning rates ( ν r), low radio-frequency (RF) irradiation fields ( ν1), and high values of the quadrupolar interaction ( ν q) that correspond to values of α=ν12/νqνr, the adiabaticity parameter, which are down to less than 10% of the traditional adiabaticity limit for a spin-5/2 (α = 0.55). The low-alpha rotational echo double resonance curve is obtained when the pulse on the quadrupolar nucleus is extended to full two rotor periods and beyond. For protons (spin-1/2) and aluminum (spin-5/2) species in the zeolite SAPO-42, a dephasing curve, which is significantly better than the regular REAPDOR experiment (pulse length of one-third of the rotor period) is obtained for a spinning rate of 13 kHz and RF fields down to 10 and even 6 kHz. Under these conditions, α is estimated to be approximately 0.05 based on an average quadrupolar coupling in zeolites. Extensive simulations support our observations suggesting the method to be robust under a large range of experimental values.

  18. Two-dimensional MAS NMR correlation protocols involving double-quantum filtering of quadrupolar spin-pairs.

    PubMed

    Edén, Mattias

    2010-05-01

    Three two-dimensional (2D) NMR homonuclear correlation techniques invoking double-quantum (2Q) filtration of the central transitions of half-integer spins are evaluated numerically and experimentally. They correlate directly detected single-quantum (1Q) coherences in the t(2) domain with either of 1Q, two-spin 2Q or single-spin multiple-quantum coherence-evolutions in the indirect (t(1)) dimension. We employ experimental (23)Na and (27)Al NMR on sodium sulfite and the natural mineral sillimanite (SiAl(2)O(5)), in conjunction with simulated 2D spectra from pairs of dipolar-recoupled spins-3/2 and 5/2 at different external magnetic fields, to compare the correlation strategies from the viewpoints of 2D spectral resolution, signal sensitivity, implementational aspects and their relative merits for establishing internuclear proximities and quadrupolar tensor orientations. PMID:20202872

  19. The "Príncipes de Asturias" nebula: a new quadrupolar planetary nebula from the IPHAS survey

    NASA Astrophysics Data System (ADS)

    Mampaso, A.; Corradi, R. L. M.; Viironen, K.; Leisy, P.; Greimel, R.; Drew, J. E.; Barlow, M. J.; Frew, D. J.; Irwin, J.; Morris, R. A. H.; Parker, Q. A.; Phillipps, S.; Rodríguez-Flores, E. R.; Zijlstra, A. A.

    2006-10-01

    Context: .The Isaac Newton Telescope Photometric Hα Survey (IPHAS) is currently mapping the Northern Galactic plane reaching to r'=20 mag with typically 1primeprime resolution. Hundreds of Planetary Nebulae (PNe), both point-like and resolved, are expected to be discovered. We report on the discovery of the first new PN from this survey: it is an unusual object located at a large galactocentric distance and has a very low oxygen abundance. Aims: .Detecting and studying new PNe will lead to improved estimates of the population size, binary fraction and lifetimes, and yield new insights into the chemistry of the interstellar medium at large galactocentric distances. Methods: .Compact nebulae are searched for in the IPHAS photometric catalogue, selecting those candidates with a strong Hα excess in the r'-Hα vs. r'-i' colour-colour diagram. Searches for extended nebulae are by visual inspection of the mosaics of continuum-subtracted Hα images at a spatial sampling of 5×5 arcsec^2. Follow-up spectroscopy enables confirmation of the PNe, and their physico-chemical study. Results: .The first planetary nebula discovered via IPHAS imagery shows an intricate morphology: there is an inner ring surrounding the central star, bright inner lobes with an enhanced waist, and very faint lobular extensions reaching up to more than 100''. We classify it as a quadrupolar PN, a rather unusual class of planetary showing two pairs of misaligned lobes. From long-slit spectroscopy we derive T_e[ Nii] =12 800±1000 K, Ne = 390±40 cm-3, and chemical abundances typical of Peimbert's type I nebulae (He/H =0.13, N/O =1.8) with an oxygen abundance of 12+log(O/H)=8.17±0.15. A kinematic distance of 7.0+4.5-3.0 kpc is derived, implying an unusually large size of >4 pc for the nebula. The photometry of the central star indicates the presence of a relatively cool companion. This, and the evidence for a dense circumstellar disk and quadrupolar morphology, all of which are rare among PNe, support

  20. Magnetic dipolar and quadrupolar transitions in two-electron atoms under exponential-cosine-screened Coulomb potential

    SciTech Connect

    Modesto-Costa, Lucas; Canuto, Sylvio; Mukherjee, Prasanta K.

    2015-03-15

    A detailed investigation of the magnetic dipolar and quadrupolar excitation energies and transition probabilities of helium isoelectronic He, Be{sup 2+}, C{sup 4+}, and O{sup 6+} have been performed under exponential cosine screened Coulomb potential generated in a plasma environment. The low-lying excited states 1s{sup 2}:{sup 1}S{sup e} → 1sns:{sup 3}S{sup e}{sub 0}, and 1snp:{sup 3}P{sup o}{sub 2} (n = 2, 3, 4, and 5) are considered. The variational time-dependent coupled Hartree-Fock scheme has been used. The effect of the confinement produced by the potential on the structural properties is investigated for increasing coupling strength of the plasma. It is noted that there is a gradual destabilization of the energy of the system with the reduction of the ionization potential and the number of excited states. The effect of the screening enhancement on the excitation energies and transition probabilities has also been investigated and the results compared with those available for the free systems and under the simple screened Coulomb potential.

  1. AN ENVELOPE DISRUPTED BY A QUADRUPOLAR OUTFLOW IN THE PRE-PLANETARY NEBULA IRAS 19475+3119

    SciTech Connect

    Hsu, Ming-Chien; Lee, Chin-Fei E-mail: cflee@asiaa.sinica.edu.tw

    2011-07-20

    IRAS 19475+3119 is a quadrupolar pre-planetary nebula (PPN), with two bipolar lobes, one in the east-west (E-W) direction and one in the southeast-northwest (SE-NW) direction. We have observed it in CO J = 2-1 with the Submillimeter Array at {approx}1'' resolution. The E-W bipolar lobe is known to trace a bipolar outflow and it is detected at high velocity. The SE-NW bipolar lobe appears at low velocity, and could trace a bipolar outflow moving in the plane of the sky. Two compact clumps are seen at low velocity around the common waist of the two bipolar lobes, spatially coincident with the two emission peaks in the NIR, tracing dense envelope material. They are found to trace the two limb-brightened edges of a slowly expanding torus-like circumstellar envelope produced in the late asymptotic giant branch phase. This torus-like envelope originally could be either a torus or a spherical shell, and it appears as it is now because of the two pairs of cavities along the two bipolar lobes. Thus, the envelope appears to be disrupted by the two bipolar outflows in the PPN phase.

  2. A study of isotropic-nematic transition of quadrupolar Gay-Berne fluid using density-functional theory approach

    NASA Astrophysics Data System (ADS)

    Singh, Ram Chandra; Ram, Jokhan

    2011-11-01

    The effects of quadrupole moments on the isotropic-nematic (IN) phase transitions are studied using the density-functional theory (DFT) for a Gay-Berne (GB) fluid for a range of length-to-breadth parameters ? in the reduced temperature range ? . The pair-correlation functions of the isotropic phase, which enter into the DFT as input parameters are found by solving the Percus-Yevick integral equation theory. The method used involves an expansion of angle-dependent functions appearing in the integral equations in terms of spherical harmonics and the harmonic coefficients are obtained by an iterative algorithm. All the terms of harmonic coefficients which involve l indices up to less than or equal to 6 are considered. The numerical accuracy of the results depends on the number of spherical harmonic coefficients considered for each orientation-dependent function. As the length-to-breadth ratio of quadrupolar GB molecules is increased, the IN transition is seen to move to lower density (and pressure) at a given temperature. It has been observed that the DFT is good to study the IN transitions in such fluids. The theoretical results have also been compared with the computer simulation results wherever they are available.

  3. A two excited state model to explain the peculiar photobehaviour of a flexible quadrupolar D-π-D anthracene derivative.

    PubMed

    Carlotti, B; Cesaretti, A; Gentili, P L; Marrocchi, A; Elisei, F; Spalletti, A

    2016-08-17

    The peculiar photobehaviour of a symmetrical arylenevinylene anthracene derivative bearing mild electron donors (alkoxy groups) at the sides of its structure has been fully comprehended through this study. An investigation into the effect of solvent polarity and temperature on the stationary fluorescence spectrum allowed a clear dual emission to be revealed. A further valuable insight was obtained, thanks to the employment of ultrafast spectroscopies. Fluorescence up-conversion measurements and the Time Resolved Area Normalised Spectra analysis provided a clear-cut proof of the presence of two distinct fluorescent states ((1)A* and (1)B*), with (1)A* being responsible for the steady-state emission in highly polar and viscous media. Femtosecond transient absorption spectra were acquired in several organic solvents of different polarity and viscosity. Interestingly, the lifetime of (1)A* was found to be dependent on solvent viscosity whereas the lifetime of (1)B* showed a trend which matches the change in solvent polarity. Indeed, the Density functional theory calculations predicted a structural rearrangement in the fully relaxed lowest excited singlet state. The (1)A* → (1)B* transition is thus likely accompanied by large amplitude motions of the molecular structure, with the (1)B* state also exhibiting a small intramolecular charge transfer character. The investigated flexible quadrupolar D-π-D system arouses therefore great interest as a novel material for applications in organic electronics and photonics. PMID:27499254

  4. Quadrupolar effects on nuclear spins of neutral arsenic donors in silicon

    NASA Astrophysics Data System (ADS)

    Franke, David P.; Pflüger, Moritz P. D.; Mortemousque, Pierre-André; Itoh, Kohei M.; Brandt, Martin S.

    2016-04-01

    We present electrically detected electron nuclear double resonance measurements of the nuclear spins of ionized and neutral arsenic donors in strained silicon. In addition to a reduction of the hyperfine coupling, we find significant quadrupole interactions of the nuclear spin of the neutral donors of the order of 10 kHz. By comparing these to the quadrupole shifts due to crystal fields measured for the ionized donors, we identify the effect of the additional electron on the electric field gradient at the nucleus. This extra component is expected to be caused by the coupling to electric field gradients created due to changes in the electron wave function under strain.

  5. TOPICAL REVIEW: Quantum spin nanotubes—frustration, competing orders and criticalities

    NASA Astrophysics Data System (ADS)

    Sakai, Tôru; Sato, Masahiro; Okamoto, Kiyomi; Okunishi, Kouichi; Itoi, Chigak

    2010-10-01

    Recent developments of theoretical studies on spin nanotubes are reviewed, especially focusing on the S = 1/2 three-leg spin tube. In contrast to the three-leg spin ladder, the tube has a spin gap in the case of the regular-triangle unit cell when the rung interaction is sufficiently large. The effective theory based on the Hubbard Hamiltonian indicates a quantum phase transition to a gapless spin liquid due to the lattice distortion to an isosceles triangle. This is also supported by the numerical diagonalization and the density matrix renormalization group analyses. Furthermore, combining analytical and numerical approaches, we reveal several novel magnetic-field-induced phenomena: Néel, dimer, chiral and/or inhomogeneous orders, a new mechanism for the magnetization plateau formation, and others. The recently synthesized spin tube materials are also briefly introduced.

  6. {open_quotes}Quadrupoled{close_quotes} materials for second-order nonlinear optics

    SciTech Connect

    Hubbard, S.F.; Petschek, R.G.; Singer, K.D.

    1997-10-01

    We describe a new approach to second-order nonlinear optical materials, namely quadrupoling. This approach is valid in the regime of Kleinman (full permutation) symmetry breaking, and thus requires a two- or three dimensional microscopic nonlinearity at wavelengths away from material resonances. This {open_quotes}quadrupolar{close_quotes} nonlinearity arises from the second rank pseudotensor of the rotationally invariant representation of the second-order nonlinear optical tensor. We have experimentally investigated candidate molecules comprised of chiral camphorquinone derivatives by measuring the scalar invariant associated with the rank two pseudotensor using hyper-Rayleigh scattering. We have found sizable scalar figures of merit for several compounds using light for which the second harmonic wavelengths are greater than 100 nm longer than the absorption peak location. At these wavelengths, the quadrupolar scalar is as large as the polar (EFISH) scalar of p-nitroaniline. Prospects for applications are discussed.

  7. Anomalous specific heat behaviour in the quadrupolar Kondo system PrV2Al20

    NASA Astrophysics Data System (ADS)

    Tsujimoto, M.; Matsumoto, Y.; Nakatsuji, S.

    2015-03-01

    We have measured the specific heat of PrV2Al20 at very low temperatures, using high quality single crystals with the residual resistivity ratio ~ 20. The high-quality single crystals exhibit clear double transitions at TQ = 0.75 K and T* = 0.65 K. These transitions are clearer and shift to higher temperature in higher quality single crystals. Besides, there was no hysteresis in those transitions in warming and cooling process of the heat capacity measurements. In the ordered state below T*, the specific heat does not exhibit exponential decay, but T4 power law dependence, indicating the gapless mode associated with the quadrupole and/or octupole degrees of freedom.

  8. Increasing the sensitivity of 2D high-resolution NMR methods applied to quadrupolar nuclei

    NASA Astrophysics Data System (ADS)

    Amoureux, J. P.; Delevoye, L.; Steuernagel, S.; Gan, Z.; Ganapathy, S.; Montagne, L.

    2005-02-01

    Gan and Kwak recently proposed a soft-pulse added mixing (SPAM) idea in the classical two-pulse multiple-quantum magic-angle spinning scheme. In the SPAM method, a soft π/2 pulse is added after the second hard-pulse (conversion pulse) and all coherence orders in between them are constructively used to obtain the signal. We, here, further extend this idea to distributed samples where the signal mainly results from echo pathways and that from anti-echo pathways dies out after a few t1 increments. We show that, with a combination of SPAM and collection of fewer anti-echoes, an enhancement of the signal to noise ratio by a factor of ca. 3 may be obtained over the z-filtered version. This may prove to be useful even for samples with long T2' relaxation times.

  9. A theoretical framework for dichroism and the resonance-enhanced scattering of x-rays by magnetic materials: II. Quadrupolar absorption events

    NASA Astrophysics Data System (ADS)

    Lovesey, Stephen W.

    1996-12-01

    Previous work with the resonant scattering length that is based on an atomic model and dipolar absorption events is extended to encompass quadrupolar absorption events. The scattering length is the common element in calculations of the attenuation coefficient, dichroism and the cross-sections for elastic and inelastic resonance-enhanced scattering of x-rays by magnetic materials. Both jj-coupling and Russell - Saunders coupling schemes for the atomic electrons are utilized; included are tables of relevant Racah unit-tensor operators for the valence shell 0953-8984/8/50/025/img1.

  10. Quadrupolar transients, cosine correlation functions, and two-dimensional exchange spectra of non-selectively excited spin-3/2 nuclei: A 7Li NMR study of the superionic conductor lithium indium phosphate

    NASA Astrophysics Data System (ADS)

    Storek, M.; Böhmer, R.

    2015-11-01

    Cos-cos stimulated echoes of non-selectively excited spin-3/2 nuclei were not exploited in studies of slow motional processes in solids and solid-like samples, so far. Based on a theoretical analysis of the quadrupolar transients which hitherto obviously precluded the application of such echoes, their utility is demonstrated for the example of 7Li NMR on the polycrystalline fast ion conductor lithium indium phosphate. Quadrupolar transients can adversely affect the shape of two- and three-pulse echo spectra and strategies are successfully tested that mitigate their impact. Furthermore, by means of suitably adapted cos-cos echo sequences an effective suppression of central-line contributions to the NMR spectra is achieved. By combining cos-cos and sin-sin datasets static two-dimensional exchange spectra were recorded that display quadrupolarly modulated off-diagonal intensity indicative of ionic motion.

  11. Modulation of Symmetry-Breaking Intramolecular Charge-Transfer Dynamics Assisted by Pendant Side Chains in π-Linkers in Quadrupolar Diketopyrrolopyrrole Derivatives.

    PubMed

    Kim, Woojae; Sung, Jooyoung; Grzybowski, Marek; Gryko, Daniel T; Kim, Dongho

    2016-08-01

    The effect of the length of pendant side chains in centrosymmetric quadrupolar molecules on dynamics of their most perplexing photophysical phenomenon, i.e., symmetry-breaking intramolecular charge transfer, has been discovered. Unexpectedly, considerable influence of length of these pendant side chains in π-linkers arose as a structural factor enabling the control of the degree of fluorescence solvatochromism. The symmetry-breaking intramolecular charge-transfer dynamics has been described on quadrupolar diketopyrrolopyrrole derivatives possessing fluorene moieties as π-linkers and diarylamino groups as electron donors. On the basis of the evolution of transient fluorescence spectra obtained by a femtosecond broadband fluorescence up-conversion spectroscopy, it was found that the relative contribution of diffusive solvation and torsional relaxation in overall spectral relaxation can be modulated by the length of pendant side chain in π-linkers. Consequently, we demonstrated that this modulation plays a significant role in determining the photophysical properties of diketopyrrolopyrroles in a polar medium. PMID:27455383

  12. 19F-decoupling of half-integer spin quadrupolar nuclei in solid-state NMR: application of frequency-swept decoupling methods.

    PubMed

    Chandran, C Vinod; Hempel, Günter; Bräuniger, Thomas

    2011-09-01

    In solid-state NMR studies of minerals and ion conductors, quadrupolar nuclei like (7)Li, (23)Na or (133)Cs are frequently situated in close proximity to fluorine, so that application of (19)F decoupling is beneficial for spectral resolution. Here, we compare the decoupling efficiency of various multi-pulse decoupling sequences by acquiring (19)F-decoupled (23)Na-NMR spectra of cryolite (Na(3)AlF(6)). Whereas the MAS spectrum is only marginally affected by application of (19)F decoupling, the 3Q-filtered (23)Na signal is very sensitive to it, as the de-phasing caused by the dipolar interaction between sodium and fluorine is three-fold magnified. Experimentally, we find that at moderate MAS speeds, the decoupling efficiencies of the frequency-swept decoupling schemes SW(f)-TPPM and SW(f)-SPINAL are significantly better than the conventional TPPM and SPINAL sequences. The frequency-swept sequences are therefore the methods of choice for efficient decoupling of quadrupolar nuclei with half-integer spin from fluorine. PMID:21856132

  13. Giant magnetothermal conductivity and magnetostriction effect in the charge ordered Nd0.8Na0.2MnO3 compound

    NASA Astrophysics Data System (ADS)

    Samantaray, B.; Khan, N.; Midya, A.; Ravi, S.; Mandal, P.

    2016-01-01

    We present results on resistivity (ρ), magnetization (M), thermal conductivity (κ), magnetostriction (\\frac{Δ L}{L(0)}) and specific heat (C p ) of the charge-orbital ordered antiferromagnetic Nd0.8Na0.2MnO3 compound. Magnetic-field-induced antiferromagnetic/charge-orbital ordered insulating to ferromagnetic metallic transition leads to giant magnetothermal conductivity and magnetostriction effect. The low-temperature irreversibility behavior in ρ, M, κ and \\frac{Δ L}{L(0)} due to field cycling together with a striking similarity among the field and temperature dependence of these parameters manifest the presence of a strong and complex spin-charge-lattice coupling in this compound. The giant magnetothermal conductivity is attributed mainly to the suppression of phonon scattering due to the destabilization of spin fluctuations and static/dynamic Jahn-Teller distortion by the application of magnetic field.

  14. External magnetic field-induced selective biodistribution of magnetoliposomes in mice

    NASA Astrophysics Data System (ADS)

    García-Jimeno, Sonia; Escribano, Elvira; Queralt, Josep; Estelrich, Joan

    2012-08-01

    This study looked at the effect of an external magnet on the biodistribution of magnetoliposomes intravenously administrated in mice (8 mg iron/kg) with and without induced acute inflammation. Our results showed that due to enhanced vascular permeability, magnetoliposomes accumulated at the site of inflammation in the absence of an external magnetic field, but the amount of iron present increased under the effect of a magnet located at the inflammation zone. This increase was dependent on the time (20 or 60 min) of exposure of the external magnetic field. It was also observed that the presence of the magnet was associated with lower amounts of iron in the liver, spleen, and plasma than was found in mice in which a magnet had not been applied. The results of this study confirm that it is possible to target drugs encapsulated in magnetic particles by means of an external magnet.

  15. Magnetic field induced indirect gap in a modulation doped quantum well

    NASA Astrophysics Data System (ADS)

    Whittaker, D. M.; Fisher, T. A.; Simmonds, P. E.; Skolnick, M. S.; Smith, R. S.; Taylor, L. L.; Bass, S. J.

    1992-02-01

    We report the first experimental evidence for the indirect fundamental band-gap developed when an in-plane magnetic field is applied to a wide, modulation-doped quantum well. In such structures, band bending may cause the lowest energy electron and hole states to be spatially separated, which leads to an induced indirect gap proportional to the field. The corresponding photoluminescence peak undergoes a large, roughly quadratic shift with field, a consequence of the behaviour of the allowed transitions involving thermalised holes and electrons with finite k. This characteristic strong diamagnetic shift is observed in spectra from both asymmetric AlGaAs/InGaAs/GaAs strained layer structures and a very wide symmetric InGaAs/InP lattice matched well. The experimental results are shown to be in good agreement with realistic self consistent calculations of the band-structure.

  16. Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Wang, Xiang; Pu, Shengli; Ji, Hongzhu; Yu, Guojun

    2012-05-01

    Ferronematic materials composed of 4-cyano-4'-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δ n) and figure of merit of optical properties ( Q = Δ n/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of Q R exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field.

  17. Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals.

    PubMed

    Wang, Xiang; Pu, Shengli; Ji, Hongzhu; Yu, Guojun

    2012-01-01

    Ferronematic materials composed of 4-cyano-4'-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δn) and figure of merit of optical properties (Q = Δn/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of QR exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field. PMID:22587542

  18. Magnetic-field-induced dynamical instabilities in an antiferromagnetic spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Pu, Zhengguo; Zhang, Jun; Yi, Su; Wang, Dajun; Zhang, Wenxian

    2016-05-01

    We theoretically investigate four types of dynamical instability, in particular the periodic and oscillatory type IO, in an antiferromagnetic spin-1 Bose-Einstein condensate in a nonzero magnetic field, by employing the coupled-mode theory and numerical method. This is in sharp contrast to the dynamical stability of the same system in zero field. Remarkably, a pattern transition from a periodic dynamical instability IO to a uniform one IIIO occurs at a critical magnetic field. All four types of dynamical instability and the pattern transition are ready to be detected in 23Na condensates within the availability of the current experimental techniques.

  19. Extremely Low Frequency Magnetic Fields Induce Spermatogenic Germ Cell Apoptosis: Possible Mechanism

    PubMed Central

    Lee, Sang-Kon; Park, Sungman; Gimm, Yoon-Myoung; Kim, Yoon-Won

    2014-01-01

    The energy generated by an extremely low frequency electromagnetic field (ELF-EMF) is too weak to directly induce genotoxicity. However, it is reported that an extremely low frequency magnetic field (ELF-MF) is related to DNA strand breakage and apoptosis. The testes that conduct spermatogenesis through a dynamic cellular process involving meiosis and mitosis seem vulnerable to external stress such as heat, MF exposure, and chemical or physical agents. Nevertheless the results regarding adverse effects of ELF-EMF on human or animal reproductive functions are inconclusive. According to the guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP; 2010) for limiting exposure to time-varying MF (1 Hz to 100 kHz), overall conclusion of epidemiologic studies has not consistently shown an association between human adverse reproductive outcomes and maternal or paternal exposure to low frequency fields. In animal studies there is no compelling evidence of causal relationship between prenatal development and ELF-MF exposure. However there is increasing evidence that EL-EMF exposure is involved with germ cell apoptosis in testes. Biophysical mechanism by which ELF-MF induces germ cell apoptosis has not been established. This review proposes the possible mechanism of germ cell apoptosis in testes induced by ELF-MF. PMID:25025060

  20. Rotating magnetic field induced oscillation of magnetic particles for in vivo mechanical destruction of malignant glioma.

    PubMed

    Cheng, Yu; Muroski, Megan E; Petit, Dorothée C M C; Mansell, Rhodri; Vemulkar, Tarun; Morshed, Ramin A; Han, Yu; Balyasnikova, Irina V; Horbinski, Craig M; Huang, Xinlei; Zhang, Lingjiao; Cowburn, Russell P; Lesniak, Maciej S

    2016-02-10

    Magnetic particles that can be precisely controlled under a magnetic field and transduce energy from the applied field open the way for innovative cancer treatment. Although these particles represent an area of active development for drug delivery and magnetic hyperthermia, the in vivo anti-tumor effect under a low-frequency magnetic field using magnetic particles has not yet been demonstrated. To-date, induced cancer cell death via the oscillation of nanoparticles under a low-frequency magnetic field has only been observed in vitro. In this report, we demonstrate the successful use of spin-vortex, disk-shaped permalloy magnetic particles in a low-frequency, rotating magnetic field for the in vitro and in vivo destruction of glioma cells. The internalized nanomagnets align themselves to the plane of the rotating magnetic field, creating a strong mechanical force which damages the cancer cell structure inducing programmed cell death. In vivo, the magnetic field treatment successfully reduces brain tumor size and increases the survival rate of mice bearing intracranial glioma xenografts, without adverse side effects. This study demonstrates a novel approach of controlling magnetic particles for treating malignant glioma that should be applicable to treat a wide range of cancers. PMID:26708022

  1. Reducing magnetic field induced noise in broad-band seismic recordings

    NASA Astrophysics Data System (ADS)

    Forbriger, Thomas

    2007-04-01

    Seismic broad-band sensors are known to be sensitive to the magnetic field. Magnetic storms and man-made disturbances of the magnetic field can produce significant noise in seismic recordings. I show that variations in the magnetic field translate directly into apparent acceleration of the seismic sensor within the period range from 60 to 1200s for all leaf-spring sensors under investigation. For a Streckeisen STS-1V this is shown even for periods down to 1s. The sensitivity is quantified in magnitude and direction. Both are quite stable over many time windows and signal periods. The sensitivities obtained by linear regression of the acceleration signal on magnetic field recordings during a magnetic storm can effectively be applied to reduce noise in seismic signals. The sensitivity varies in magnitude from sensor to sensor but all are in the range from 0.05 to 1.2ms-2T-1. Seismograms from sensors at Black Forest Observatory (BFO) and stations of the German Regional Seismic Network were investigated. Although these are mainly equipped with leaf-spring sensors, the problem is not limited to this type of instrument. The effect is not observable on the horizontal component STS-1s at BFO while it is significant in the recordings of the vertical STS-1. The main difference between these instruments is the leaf-spring suspension in the vertical component that appears to be the source of the trouble. The suspension springs are made of temperature compensated Elinvar alloys that inherently are ferromagnetic and may respond to the magnetic field in various ways. However, the LaCoste Romberg ET-19 gravimeter at BFO, which uses this material too, does not respond to magnetic storms at a similar magnitude neither do the Invar-wire strainmeters. An active shielding, composed of three Helmholtz coils and a feedback system, is installed at station Stuttgart and provides an improvement of signal-to-noise ratio by almost a factor of 20 at this particular station. The passive Permalloy shielding commonly installed with STS-1V sensors performs similarly well.

  2. External magnetic field-induced selective biodistribution of magnetoliposomes in mice

    PubMed Central

    2012-01-01

    This study looked at the effect of an external magnet on the biodistribution of magnetoliposomes intravenously administrated in mice (8 mg iron/kg) with and without induced acute inflammation. Our results showed that due to enhanced vascular permeability, magnetoliposomes accumulated at the site of inflammation in the absence of an external magnetic field, but the amount of iron present increased under the effect of a magnet located at the inflammation zone. This increase was dependent on the time (20 or 60 min) of exposure of the external magnetic field. It was also observed that the presence of the magnet was associated with lower amounts of iron in the liver, spleen, and plasma than was found in mice in which a magnet had not been applied. The results of this study confirm that it is possible to target drugs encapsulated in magnetic particles by means of an external magnet. PMID:22883385

  3. Magnetic-Field-Induced Relativistic Properties in Type-I and Type-II Weyl Semimetals.

    PubMed

    Tchoumakov, Serguei; Civelli, Marcello; Goerbig, Mark O

    2016-08-19

    We investigate Weyl semimetals with tilted conical bands in a magnetic field. Even when the cones are overtilted (type-II Weyl semimetal), Landau-level quantization can be possible as long as the magnetic field is oriented close to the tilt direction. Most saliently, the tilt can be described within the relativistic framework of Lorentz transformations that give rise to a rich spectrum, displaying new transitions beyond the usual dipolar ones in the optical conductivity. We identify particular features in the latter that allow one to distinguish between semimetals of different types. PMID:27588870

  4. Giant effective mass deviations near the magnetic field-induced minigap in double quantum wells

    SciTech Connect

    Harff, N.E. |; Simmons, J.A.; Lyo, S.K.; Klem, J.F.; Goodnick, S.M.

    1994-09-01

    The authors report major deviations in the electron effective mass m* near the partial energy gap, or minigap, formed in strongly coupled double quantum wells (QWs) by an anticrossing of the two QW dispersion curves. The anticrossing and minigap are induced by an in-plane magnetic field B{sub {parallel}} and give rise to large distortions in the Fermi surface and density of states, including a Van Hove singularity. Sweeping B{sub {parallel}} moves the minigap through the Fermi level, with the upper and lower gap edges producing a sharp maximum and minimum in the low-temperature in-plane conductance, in agreement with theoretical calculations. The temperature dependence of Shubnikov-de Haas (SdH) oscillations appearing in a tilted magnetic field yield a decreased m* {le} 1/3 m*{sub GaAs} near the upper gap edge, and indicate an increase in m* near the lower gap edge.

  5. Ensemble simulations of the magnetic field induced by global ocean circulation: Estimating the uncertainty

    NASA Astrophysics Data System (ADS)

    Irrgang, Christopher; Saynisch, Jan; Thomas, Maik

    2016-03-01

    The modeling of the ocean global circulation induced magnetic field is affected by various uncertainties that originate from errors in the input data and from the model itself. The amount of aggregated uncertainties and their effect on the modeling of electromagnetic induction in the ocean is unknown. For many applications, however, the knowledge of uncertainties in the modeling is essential. To investigate the uncertainty in the modeling of motional induction at the sea surface, simulation experiments are performed on the basis of different error scenarios and error covariance matrices. For these error scenarios, ensembles of an ocean general circulation model and an electromagnetic induction model are generated. This ensemble-based approach allows to estimate both the spatial distribution and temporal variation of the uncertainty in the ocean-induced magnetic field. The largest uncertainty in the ocean-induced magnetic field occurs in the area of the Antarctic Circumpolar Current. Local maxima reach values of up to 0.7 nT. The estimated global annual mean uncertainty in the ocean-induced magnetic field ranges from 0.1 to 0.4 nT. The relative amount of uncertainty reaches up to 30% of the signal strength with largest values in regions in the northern hemisphere. The major source of uncertainty is found to be introduced by wind stress from the atmospheric forcing of the ocean model. In addition, the temporal evolution of the uncertainty in the induced magnetic field shows distinct seasonal variations. Specific regions are identified which are robust with respect to the introduced uncertainties.

  6. Magnetic fluid hyperthermia (MFH): Cancer treatment with AC magnetic field induced excitation of biocompatible superparamagnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Jordan, Andreas; Scholz, Regina; Wust, Peter; Fähling, Horst; Felix, Roland

    1999-07-01

    The story of hyperthermia with small particles in AC magnetic fields started in the late 1950s, but most of the studies were unfortunately conducted with inadequate animal systems, inexact thermometry and poor AC magnetic field parameters, so that any clinical implication was far behind the horizon. More than three decades later, it was found, that colloidal dispersions of superparamagnetic (subdomain) iron oxide nanoparticles exhibit an extraordinary specific absorption rate (SAR [ W/ g]), which is much higher at clinically tolerable H 0 f combinations in comparison to hysteresis heating of larger multidomain particles. This was the renaissance of a cancer treatment method, which has gained more and more attention in the last few years. Due to the increasing number of randomized clinical trials preferentially in Europe with conventional E-field hyperthermia systems, the general medical and physical experience in hyperthermia application is also rapidly growing. Taking this increasing clinical experience carefully into account together with the huge amount of new biological data on heat response of cells and tissues, the approach of magnetic fluid hyperthermia (MFH) is nowadays more promising than ever before. The present contribution reviews the current state of the art and some of the future perspectives supported by advanced methods of the so-called nanotechnology.

  7. Electronic scattering of pseudo-magnetic field induced by local bump in graphene

    NASA Astrophysics Data System (ADS)

    Yang, Mou; Cui, Yan; Wang, Rui-Qiang; Zhao, Hong-Bo

    2012-10-01

    We investigated the electronic scattering properties of a local bump strain in graphene sheet in frame of Born approximation. The differential scattering cross section is a function of outgoing and incident angles and has the six-fold rotational symmetry with respect to both angles. The incident plane wave is scattered into two backward fan-waves in different directions in low energy limit and is split into two branches spanning the angle reversely proportional to the incident wavevector k in high energy limit. The total scattering cross section depends on incident wavevector by the form k5 in the former limit, while it is independent of k and sensitive to the incident orientation in the latter limit. We explained these features using the symmetry of the strain-induced pseudo-magnetic field.

  8. Influences of different parameters on the microstructure of magnetic-field-induced self-assembled film

    NASA Astrophysics Data System (ADS)

    Dan, X.; Yang, J. J.

    2016-07-01

    Self-assembled films with needle-like microarrays were fabricated using a mixture of cobalt and fluorocarbon resin under a magnetic field. The various influences of magnetic powder content, viscosity and size distribution on the structure of the self-assembled films were investigated. The self-assembled film morphologies were characterized by stereomicroscope and scanning electron microscopy. Experimental results indicate that an increase in magnetic powder content results in greater unit height and diameter, and that a reduction in viscosity results in increasing array density and decreasing unit width. Additionally, particles with narrow size distribution were able to attain more regular microarray structures. The structural alterations were closely related to numerous effects such as van der Waals forces, dipole-dipole interactions, and external-dipole interactions. The self-assembled film demonstrated magnetic anisotropy, as identified by vibrating sample magnetometry (VSM).

  9. Inner Core Anisotropy Due to the Magnetic Field--induced Preferred Orientation of Iron.

    PubMed

    Karato, S

    1993-12-10

    Anisotropy of the inner core of the Earth is proposed to result from the lattice preferred orientation of anisotropic iron crystals during their solidification in the presence of a magnetic field. The resultant seismic anisotropy is related to the geometry of the magnetic field in the core. This hypothesis implies that the observed anisotropy (fast velocity along the rotation axis) indicates a strong toroidal field in the core, which supports a strong field model for the geodynamo if the inner core is made of hexagonal close-packed iron. PMID:17781788

  10. Magnetic Field Induced Shear Flow in a Strongly Coupled Complex Plasma

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, P.; Konopka, U.; Jiang, K.; Morfill, G.

    2011-11-01

    We address an experimental observation of shear flow of micron sized dust particles in a strongly coupled complex plasma in presence of a homogeneous magnetic field. Two concentric Aluminum rings of different size are placed on the lower electrode of a radio frequency (rf) parallel plate discharge. The modified local sheath electric field is pointing outward/inward close to the inner/outher ring, respectively. The microparticles, confined by the rings and subject to an ion wind that driven by the local sheath electric field and deflected by an externally applied magnetic field, start flowing in azimuthal direction. Depending upon the rf amplitudes on the electrodes, the dust layers show rotation in opposite direction at the edges of the ring-shaped cloud resulting a strong shear in its center. MD simulations shows a good agreement with the experimental results.

  11. Magnetic-field-induced Metallic Phase at Low Temperature in Two-dimensional Superconductors

    NASA Astrophysics Data System (ADS)

    Murakami, E.; Ochi, A.; Kawamura, Y.; Kaneko, S.; Okuma, S.

    We measure the resistance R(T) at low temperature T in various fields B for an amorphous (a-)MoxGe1-x thin film with weak disorder (i.e., small normal-state resistance Rn) and weak pinning. We confirm the presence of the intervening metallic phase between superconducting and insulating phases, consistent with earlier work on the a-MoxGe1-x thin film with stronger disorder. The result is in contrast to what has been observed for the a-MoxSi1-x thin films with stronger pinning, in which the B-driven superconductor-insulator transition is clearly visible. We also find that for the a-MoxGe1-x thin films the reduced crossover temperature, below which the activated behavior of R(T) in B changes to the metallic behavior, and field region of the intervening metallic phase are significantly suppressed for the less disordered film. We interpret the results in terms of decreased quantum fluctuation effects due to reduced Rn.

  12. Magnetic field-induced reactions on the surface of chloroaluminum phthalocyanine thin films

    NASA Astrophysics Data System (ADS)

    Basova, Tamara; Plyashkevich, Vladimir; Petraki, Fotini; Peisert, Heiko; Chassé, Thomas

    2011-03-01

    The μ-(oxo)bis[phthalocyaninato] aluminum(III) (AlPc)2O films, with the crystallites oriented preferably in one direction, were obtained via chemical transformation of chloroaluminum(III) phthalocyanine AlClPc film upon its annealing in magnetic field. A comparative analysis of the influence of postdeposition annealing without and under applied magnetic field of 1 T on composition and morphology of AlClPc films has been carried out. The chemical transformation of AlClPc to (AlPc)2O on the substrate surface is studied by the methods of UV-vis and infrared spectroscopies, Raman, x-ray photoelectron spectroscopy as well as atomic force microscopy. Two interesting effects were observed upon heating the AlClPc films in magnetic field of 1 T. First, the temperature of the chemical transformation of AlClPc to (AlPc)2O decreased from 300 °C to 200 °C when magnetic field was applied during postdeposition annealing. Second, the formation of (AlPc)2O films with elongated crystallites with a preferential orientation was observed. The heating of (AlPc)2O films in a magnetic field at the same conditions did not demonstrate any effect on the structure and morphology of these films.

  13. Magnetic field-induced reactions on the surface of chloroaluminum phthalocyanine thin films.

    PubMed

    Basova, Tamara; Plyashkevich, Vladimir; Petraki, Fotini; Peisert, Heiko; Chassé, Thomas

    2011-03-28

    The μ-(oxo)bis[phthalocyaninato] aluminum(III) (AlPc)(2)O films, with the crystallites oriented preferably in one direction, were obtained via chemical transformation of chloroaluminum(III) phthalocyanine AlClPc film upon its annealing in magnetic field. A comparative analysis of the influence of postdeposition annealing without and under applied magnetic field of 1 T on composition and morphology of AlClPc films has been carried out. The chemical transformation of AlClPc to (AlPc)(2)O on the substrate surface is studied by the methods of UV-vis and infrared spectroscopies, Raman, x-ray photoelectron spectroscopy as well as atomic force microscopy. Two interesting effects were observed upon heating the AlClPc films in magnetic field of 1 T. First, the temperature of the chemical transformation of AlClPc to (AlPc)(2)O decreased from 300 °C to 200 °C when magnetic field was applied during postdeposition annealing. Second, the formation of (AlPc)(2)O films with elongated crystallites with a preferential orientation was observed. The heating of (AlPc)(2)O films in a magnetic field at the same conditions did not demonstrate any effect on the structure and morphology of these films. PMID:21456691

  14. Parallel magnetic-field-induced conductance fluctuations in one- and two-subband ballistic quantum dots

    NASA Astrophysics Data System (ADS)

    Gustin, C.; Faniel, S.; Hackens, B.; Melinte, S.; Shayegan, M.; Bayot, V.

    2003-12-01

    We report on conductance fluctuations of ballistic quantum dots in a strictly parallel magnetic field B. The quantum dots are patterned in two-dimensional electron gases (2DEG’s), confined to 15- and 45-nm-thick GaAs quantum wells (QW) with one and two occupied subbands at B=0, respectively. For both dots we observe universal conductance fluctuations (UCF’s) and, in the case of the wide QW dot, a reduction in their amplitude at large B. Our data suggest that the finite thickness of the 2DEG and the orbital effect are responsible for the parallel B-induced UCF’s.

  15. Observation of magnetic field-induced contraction of fission yeast cells using optical projection microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Xi; Beckwith, Andrew; Miller, John; Wood, Lowell

    2004-12-01

    The charges in live cells interact with or produce electric fields, which results in enormous dielectric responses, flexoelectricity, and related phenomena. Here we report on a contraction of Schizosaccharomyces pombe (fission yeast) cells induced by magnetic fields, as observed using a phase-sensitive projection imaging technique. Unlike electric fields, magnetic fields only act on moving charges. The observed behavior is therefore quite remarkable, and may result from a contractile Lorentz force acting on diamagnetic screening currents. This would indicate extremely high intracellular charge mobilities. Besides, we observed a large electro-optic response from fission yeast cells.

  16. Observation of magnetic field-induced contraction of fission yeast cells using optical projection microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Xi; Beckwith, A. W.

    2005-03-01

    The charges in live cells interact with or produce electric fields, which results in enormous dielectric responses, flexoelectricity, and related phenomena. Here we report on a contraction of Schizosaccharomyces pombe (fission yeast) cells induced by magnetic fields, as observed using a phase-sensitive projection imaging technique. Unlike electric fields, magnetic fields only act on moving charges. The observed behavior is therefore quite remarkable, and may result from a contractile Lorentz force acting on diamagnetic screening currents. This would indicate extremely high intracellular charge mobilities. Besides, we observed a large electro-optic response from fission yeast cells.

  17. Weak extremely-low-frequency magnetic field-induced regeneration anomalies in the planarian, Dugesia tigrina

    SciTech Connect

    Jenrow, K.A.; Smith, C.H.; Liboff, A.R.

    1996-12-31

    The authors recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. The authors report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 {micro}T. These anomalies often culminate in the complete disaggregation of the organism. Similar to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 {micro} V/m. The addition of either 51.1 or 78.4 {micro}T DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas the previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling.

  18. Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system

    NASA Astrophysics Data System (ADS)

    Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng

    2015-12-01

    We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. We uncover the phenomenon of flow pattern reversal as the strength of the magnetic field is increased through a critical value. In between the regimes of pro-grade and retrograde flow rotations, standing waves with zero angular velocities can emerge. A striking finding is that, under a transverse magnetic field, a second reversal in the flow pattern direction can occur, where the flow pattern evolves into pro-grade rotation again from a retrograde state. Flow reversal is relevant to intriguing phenomena in nature such as geomagnetic reversal. Our results suggest that, in ferrofluids, flow pattern reversal can be induced by varying a magnetic field in a controlled manner, which can be realized in laboratory experiments with potential applications in the development of modern fluid devices.

  19. Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system

    PubMed Central

    Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng

    2015-01-01

    We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. We uncover the phenomenon of flow pattern reversal as the strength of the magnetic field is increased through a critical value. In between the regimes of pro-grade and retrograde flow rotations, standing waves with zero angular velocities can emerge. A striking finding is that, under a transverse magnetic field, a second reversal in the flow pattern direction can occur, where the flow pattern evolves into pro-grade rotation again from a retrograde state. Flow reversal is relevant to intriguing phenomena in nature such as geomagnetic reversal. Our results suggest that, in ferrofluids, flow pattern reversal can be induced by varying a magnetic field in a controlled manner, which can be realized in laboratory experiments with potential applications in the development of modern fluid devices. PMID:26687638

  20. Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system.

    PubMed

    Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng

    2015-01-01

    We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. We uncover the phenomenon of flow pattern reversal as the strength of the magnetic field is increased through a critical value. In between the regimes of pro-grade and retrograde flow rotations, standing waves with zero angular velocities can emerge. A striking finding is that, under a transverse magnetic field, a second reversal in the flow pattern direction can occur, where the flow pattern evolves into pro-grade rotation again from a retrograde state. Flow reversal is relevant to intriguing phenomena in nature such as geomagnetic reversal. Our results suggest that, in ferrofluids, flow pattern reversal can be induced by varying a magnetic field in a controlled manner, which can be realized in laboratory experiments with potential applications in the development of modern fluid devices. PMID:26687638

  1. Magnetic field induced trions in a Telluride-based II-VI material

    NASA Astrophysics Data System (ADS)

    Sujanah, P.; John Peter, A.; Lee, Chang Woo

    2016-04-01

    Effects of geometrical confinement and magnetic field strength on the binding energies of trions (positive trion and negative trion) in a CdTe/ZnTe parabolic dot are investigated. Coulomb interaction energy is obtained by employing Hartree potential and the results are found numerically. The modified Chandrasekhar wavefunctions are employed to obtain the respective energies. The confined energies and the respective binding energies of charged trions are investigated by the self-consistent method. The Poisson equation is used to find the electron and hole potentials. The dielectric mismatch is included throughout the calculations. Magneto-optical transition energies for charged trions in the presence of magnetic field are observed. The effective Landé factor is brought out. Raman shift and the Raman intensity of positive and negative trions for various magnetic field strengths in the CdTe/ZnTe nanostructures are investigated. The dependence of Raman resonance on the magnetic field and the geometrical confinement effect is brought out.

  2. Magnetic field induced quantum dot brightening in liquid crystal synergized magnetic and semiconducting nanoparticle composite assemblies

    SciTech Connect

    Amaral, Jose Jussi; Wan, Jacky; Rodarte, Andrea L.; Ferri, Christopher; Quint, Makiko T.; Pandolfi, Ronald J.; Scheibner, Michael; Hirst, Linda S.; Ghosh, Sayantani

    2014-10-22

    The design and development of multifunctional composite materials from artificial nano-constituents is one of the most compelling current research areas. This drive to improve over nature and produce ‘meta-materials’ has met with some success, but results have proven limited with regards to both the demonstration of synergistic functionalities and in the ability to manipulate the material properties post-fabrication and in situ. Here, magnetic nanoparticles (MNPs) and semiconducting quantum dots (QDs) are co-assembled in a nematic liquid crystalline (LC) matrix, forming composite structures in which the emission intensity of the quantum dots is systematically and reversibly controlled with a small applied magnetic field (<100 mT). This magnetic field-driven brightening, ranging between a two- to three-fold peak intensity increase, is a truly cooperative effect: the LC phase transition creates the co-assemblies, the clustering of the MNPs produces LC re-orientation at atypical low external field, and this re-arrangement produces compaction of the clusters, resulting in the detection of increased QD emission. These results demonstrate a synergistic, reversible, and an all-optical process to detect magnetic fields and additionally, as the clusters are self-assembled in a fluid medium, they offer the possibility for these sensors to be used in broad ranging fluid-based applications.

  3. Enhanced magnetic-field-induced optical properties of nanostructured magnetic fluids by doping nematic liquid crystals

    PubMed Central

    2012-01-01

    Ferronematic materials composed of 4-cyano-4′-pentylbiphenyl nematic liquid crystal and oil-based Fe3O4 magnetic fluid were prepared using ultrasonic agitation. The birefringence (Δn) and figure of merit of optical properties (Q = Δn/α, where α is the extinction coefficient) of pure magnetic fluids and the as-prepared ferronematic materials were examined and compared. The figure of merit of optical properties weighs the birefringence and extinction of the materials and is more appropriate to evaluate their optical properties. Similar magnetic-field- and magnetic-particle-concentration-dependent properties of birefringence and figure of merit of optical properties were obtained for the pure magnetic fluids and the ferronematic materials. For the ferronematic materials, the values of Q increase with the volume fractions of nematic liquid crystal under certain fixed field strength and are larger than those of their corresponding pure magnetic fluids at high field region. In addition, the enhancement of Q value increases monotonously with the magnetic field and becomes remarkable when the applied magnetic field is beyond 50 mT. The maximum relative enhanced value of QR exceeds 6.8% in our experiments. The results of this work may conduce to extend the pragmatic applications of nanostructured magnetic fluids in optical field. PMID:22587542

  4. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    NASA Astrophysics Data System (ADS)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-06-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  5. Magnetic Field-Induced Giant Enhancement of Electron-Phonon Energy Transfer in Strongly Disordered Conductors

    NASA Astrophysics Data System (ADS)

    Shtyk, A. V.; Feigel'man, M. V.; Kravtsov, V. E.

    2013-10-01

    Relaxation of soft modes (e.g., charge density in gated semiconductor heterostructures, spin density in the presence of magnetic field) slowed down by disorder may lead to giant enhancement of energy transfer (cooling power) between overheated electrons and phonons at low bath temperature. We show that in strongly disordered systems with time-reversal symmetry broken by external or intrinsic exchange magnetic field the cooling power can be greatly enhanced. The enhancement factor as large as 102 at magnetic field B˜10T in 2D InSb films is predicted. A similar enhancement is found for the ultrasound attenuation.

  6. Magnetic field-induced control of transport in multiterminal focusing quantum billiards

    NASA Astrophysics Data System (ADS)

    Morfonios, C.; Buchholz, D.; Schmelcher, P.

    2011-05-01

    By exploring the four-terminal transmission of a semielliptic open quantum billiard in dependence of its geometry and an applied magnetic field, it is shown that a controllable switching of currents between the four terminals can be obtained. Depending on the eccentricity of the semiellipse and the width and placement of the leads, high transmittivity at zero magnetic field is reached either through states guided along the curved boundary or focused onto the straight boundary of the billiard. For small eccentricity, attachment of leads at the ellipse foci can yield optimized corresponding transmission, while departures from this behavior demonstrate the inapplicability of solely classical considerations in the deep quantum regime. The geometrically determined transmission is altered by the phase-modulating and deflecting effect of the magnetic field, which switches the pairs of leads connected by high transmittivity. It is shown that the elliptic boundary is responsible for these very special transport properties. At higher field strengths edge states form and the multiterminal transmission coefficients are determined by the topology of the billiard. The combination of magnetotransport with geometrically optimized transmission behavior leads to an efficient control of the current through the multiterminal structure.

  7. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    NASA Astrophysics Data System (ADS)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-08-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  8. Magnetic field induced quantum dot brightening in liquid crystal synergized magnetic and semiconducting nanoparticle composite assemblies.

    PubMed

    Amaral, Jose Jussi; Wan, Jacky; Rodarte, Andrea L; Ferri, Christopher; Quint, Makiko T; Pandolfi, Ronald J; Scheibner, Michael; Hirst, Linda S; Ghosh, Sayantani

    2015-01-14

    The design and development of multifunctional composite materials from artificial nano-constituents is one of the most compelling current research areas. This drive to improve over nature and produce 'meta-materials' has met with some success, but results have proven limited with regards to both the demonstration of synergistic functionalities and in the ability to manipulate the material properties post-fabrication and in situ. Here, magnetic nanoparticles (MNPs) and semiconducting quantum dots (QDs) are co-assembled in a nematic liquid crystalline (LC) matrix, forming composite structures in which the emission intensity of the quantum dots is systematically and reversibly controlled with a small applied magnetic field (<100 mT). This magnetic field-driven brightening, ranging between a two- to three-fold peak intensity increase, is a truly cooperative effect: the LC phase transition creates the co-assemblies, the clustering of the MNPs produces LC re-orientation at atypical low external field, and this re-arrangement produces compaction of the clusters, resulting in the detection of increased QD emission. These results demonstrate a synergistic, reversible, and an all-optical process to detect magnetic fields and additionally, as the clusters are self-assembled in a fluid medium, they offer the possibility for these sensors to be used in broad ranging fluid-based applications. PMID:25354546

  9. Magnetic field induced quantum dot brightening in liquid crystal synergized magnetic and semiconducting nanoparticle composite assemblies

    DOE PAGESBeta

    Amaral, Jose Jussi; Wan, Jacky; Rodarte, Andrea L.; Ferri, Christopher; Quint, Makiko T.; Pandolfi, Ronald J.; Scheibner, Michael; Hirst, Linda S.; Ghosh, Sayantani

    2014-10-22

    The design and development of multifunctional composite materials from artificial nano-constituents is one of the most compelling current research areas. This drive to improve over nature and produce ‘meta-materials’ has met with some success, but results have proven limited with regards to both the demonstration of synergistic functionalities and in the ability to manipulate the material properties post-fabrication and in situ. Here, magnetic nanoparticles (MNPs) and semiconducting quantum dots (QDs) are co-assembled in a nematic liquid crystalline (LC) matrix, forming composite structures in which the emission intensity of the quantum dots is systematically and reversibly controlled with a small appliedmore » magnetic field (<100 mT). This magnetic field-driven brightening, ranging between a two- to three-fold peak intensity increase, is a truly cooperative effect: the LC phase transition creates the co-assemblies, the clustering of the MNPs produces LC re-orientation at atypical low external field, and this re-arrangement produces compaction of the clusters, resulting in the detection of increased QD emission. These results demonstrate a synergistic, reversible, and an all-optical process to detect magnetic fields and additionally, as the clusters are self-assembled in a fluid medium, they offer the possibility for these sensors to be used in broad ranging fluid-based applications.« less

  10. Terahertz probes of magnetic field induced spin reorientation in YFeO{sub 3} single crystal

    SciTech Connect

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

    2015-03-02

    Using the terahertz time-domain spectroscopy, we demonstrate the spin reorientation of a canted antiferromagnetic YFeO{sub 3} single crystal, by evaluating the temperature and magnetic field dependence of resonant frequency and amplitude for the quasi-ferromagnetic (FM) and quasi-antiferromagnetic modes (AFM), a deeper insight into the dynamics of spin reorientation in rare-earth orthoferrites is established. Due to the absence of 4f-electrons in Y ion, the spin reorientation of Fe sublattices can only be induced by the applied magnetic field, rather than temperature. In agreement with the theoretical predication, the frequency of FM mode decreases with magnetic field. In addition, an obvious step of spin reorientation phase transition occurs with a relatively large applied magnetic field of 4 T. By comparison with the family members of RFeO{sub 3} (R = Y{sup 3+} or rare-earth ions), our results suggest that the chosen of R would tailor the dynamical rotation properties of Fe ions, leading to the designable spin switching in the orthoferrite antiferromagnetic systems.

  11. Control of Multipolar and Orbital Order in Perovskite-like [C(NH2)3]CuxCd1-x(HCOO)3 Metal-Organic Frameworks.

    PubMed

    Evans, Nicole L; Thygesen, Peter M M; Boström, Hanna L B; Reynolds, Emily M; Collings, Ines E; Phillips, Anthony E; Goodwin, Andrew L

    2016-08-01

    We study the compositional dependence of molecular orientation (multipolar) and orbital (quadrupolar) order in the perovskite-like metal-organic frameworks [C(NH2)3]CuxCd1-x(HCOO)3. Upon increasing the fraction x of Jahn-Teller-active Cu(2+), we observe an orbital disorder/order transition and a multipolar reorientation transition, each occurring at distinct critical compositions xo = 0.45(5) and xm = 0.55(5). We attribute these transitions to a combination of size, charge distribution, and percolation effects. Our results establish the accessibility in formate perovskites of novel structural degrees of freedom beyond the familiar dipolar terms responsible for (anti)ferroelectric order. We discuss the implications of cooperative quadrupolar and multipolar states for the design of relaxor-like hybrid perovskites. PMID:27414161

  12. Flipping of magnetic moments induced by the first-order phase transition in MnAs disks on GaAs(001)

    NASA Astrophysics Data System (ADS)

    Takagaki, Y.; Herfort, J.; Däweritz, L.; Ploog, K. H.

    2006-12-01

    The relaxation of magnetization in MnAs nanomagnets fabricated on GaAs(001) substrates consists of three exponential decays that are associated with the first-order phase transition between the ferromagnetic and nonmagnetic phases of MnAs and fast and slow flipping processes of magnetic moments. Not only the phase-transition component but also the fast-relaxation component become appreciable in the narrow temperature range of the thermal hysteresis of the phase transition. The magnetic moments are suggested to be rotated by virtual phase-transition processes. A brief expansion of the lattice constants of MnAs through the magnetic-field-induced phase transition is found to generate a memory effect and permanently elongate the decay times.

  13. From Dark to Bright: First-Order Perturbation Theory with Analytical Mode Normalization for Plasmonic Nanoantenna Arrays Applied to Refractive Index Sensing

    NASA Astrophysics Data System (ADS)

    Weiss, T.; Mesch, M.; Schäferling, M.; Giessen, H.; Langbein, W.; Muljarov, E. A.

    2016-06-01

    We present a first-order perturbation theory to calculate the frequency shift and linewidth change of photonic resonances in one- and two-dimensional periodic structures under modifications of the surrounding refractive index. Our method is based on the resonant state expansion, for which we extend the analytical mode normalization to periodic structures. We apply this theory to calculate the sensitivity of bright dipolar and much darker quadrupolar plasmonic modes by determining the maximum shift and optimal sensing volume.

  14. From Dark to Bright: First-Order Perturbation Theory with Analytical Mode Normalization for Plasmonic Nanoantenna Arrays Applied to Refractive Index Sensing.

    PubMed

    Weiss, T; Mesch, M; Schäferling, M; Giessen, H; Langbein, W; Muljarov, E A

    2016-06-10

    We present a first-order perturbation theory to calculate the frequency shift and linewidth change of photonic resonances in one- and two-dimensional periodic structures under modifications of the surrounding refractive index. Our method is based on the resonant state expansion, for which we extend the analytical mode normalization to periodic structures. We apply this theory to calculate the sensitivity of bright dipolar and much darker quadrupolar plasmonic modes by determining the maximum shift and optimal sensing volume. PMID:27341256

  15. Earth's magnetic field enabled scalar coupling relaxation of 13C nuclei bound to fast-relaxing quadrupolar 14N in amide groups

    NASA Astrophysics Data System (ADS)

    Chiavazza, Enrico; Kubala, Eugen; Gringeri, Concetta V.; Düwel, Stephan; Durst, Markus; Schulte, Rolf F.; Menzel, Marion I.

    2013-02-01

    Scalar coupling relaxation, which is usually only associated with closely resonant nuclei (e.g., 79Br-13C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-13C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T1 shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar 14N adjacent to the 13C nucleus in the amide group. This contribution is only effective in low magnetic fields (i.e., less than 800 μT) and prevents the use of molecules bearing the 13C-amide group as hyperpolarized MRS/MRI probes. In the present work, this hypothesis is explored both theoretically and experimentally. The results show that high hyperpolarization levels can be retained using either a 15N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner.

  16. Cobalt Polyoxometalate Co4V2W18O68(10-): A Critical Investigation of Its Synthesis, Purity, and Observed (51)V Quadrupolar NMR.

    PubMed

    Folkman, Scott J; Kirner, Joel T; Finke, Richard G

    2016-06-01

    The vanadium-containing cobalt polyoxometalate (Co-POM) Co4V2W18O68(10-) (hereafter Co4V2W18) has been reported to be a stable, homogeneous water-oxidation catalyst, one with a claimed record turnover frequency that is also reportedly 200-fold faster than its phosphorus congener, Co4P2W18O68(10-). The claimed superior water-oxidation catalysis activity of the vanadium congener, Co4V2W18, rests squarely on the reported synthesis of Co4V2W18, its purity, and its stability in both the solid-state and in solution. Attempts to repeat the preparation of Co4V2W18 by either of two literature syntheses, along with the other studies reported herein, led to the discovery of multiple, convoluted problems in the prior literature of Co4V2W18. The three most serious of those problems proved to be the prior misunderstanding of the quadrupolar (herein (51)V) NMR peak widths in complexes that also contain paramagnetic metals such as Co(II), the incorrect assignment of a -506.8 ppm (51)V NMR to Co4V2W18, and then the use of that -506.8 peak to argue for the stability of Co4V2W18 in solution. The results are reported in a somewhat historical, "story" fashion en route to elucidating and fully supporting the 11 insights and take-home messages listed in the Summary and Conclusions section. PMID:27159211

  17. Ab initio calculations of external-field shifts of the 661-nm quadrupolar clock transition in neutral Ag atoms

    SciTech Connect

    Topcu, Suat; Nasser, Jamil; Daku, Latevi Max Lawson; Fritzsche, Stephan

    2006-04-15

    Frequency shifts of the Ag I 4d{sup 10}5s {sup 2}S{sub 1/2}(F=0,M{sub F}=0) to 4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2}(F{sup '}=2,M{sub F{sup '}}=0) electric-quadrupole transition at 330.6 nm due to external fields are calculated using multiconfigurational self-consistent field methods. As this forbidden transition is free from first order Doppler and Zeeman effects, it is under investigation for the realization of an atomic optical clock. The calculated perturbations are the light shift, the blackbody frequency shift, and the quadratic Zeeman shift. Results show that a total uncertainty of 10{sup -18} could be reach without confining the atoms in a Lamb-Dicke regime in an optical lattice.

  18. Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

    NASA Astrophysics Data System (ADS)

    Fujioka, J.; Yasue, T.; Miyasaka, S.; Yamasaki, Y.; Arima, T.; Sagayama, H.; Inami, T.; Ishii, K.; Tokura, Y.

    2010-10-01

    We have investigated the spin/orbital phase diagram in the perovskite orthovanadate RVO3 ( R=Eu , Y, Dy, and Ho) by measurements of magnetization, dielectric constant, specific heat, Raman scattering spectra, and x-ray diffraction, focusing on the interplay between the V3d spin and the 4f moment of the R ion. The thermally induced phase transition between the C-type spin/G-type orbital ordered state and the G-type spin/C-type orbital ordered state is observed for Eu1-xYxVO3 (x=0-0.52) without 4f moment. By comparing this phase diagram with the spin/orbital ordering in TbVO3 , it is evident that the critical competition between the C-type spin/G-type orbital ordered phase and the G-type spin/C-type orbital ordered one depends not only on the GdFeO3 -type lattice distortion but also on the presence of the 4f moment of the R ion. The magnetic field induced phase transition of the spin/orbital ordering is achieved concomitantly with polarizing R4f moments for DyVO3 and HoVO3 . For DyVO3 , the G-type spin/C-type orbital ordered phase is switched to the C-type spin/G-type orbital ordered one by applying a moderate magnetic field around 3 T. By contrast, the G-type spin/C-type orbital ordering is rather favored under the magnetic field in HoVO3 . The results cannot be uniquely explained in terms of the exchange interaction between the V3d spin and the R -ion 4f moment. The coupling of the R4f moment polarization with the lattice distortion tied with the orbital ordering of the V3d sublattice may also be relevant to this field induced phase transition.

  19. Dynamics of spin I=3/2 under spin-locking conditions in an ordered environment.

    PubMed

    van der Maarel, J R; Jesse, W; Hancu, I; Woessner, D E

    2001-08-01

    We have derived approximate analytic solutions to the master equation describing the evolution of the spin I=3/2 density operator in the presence of a radio-frequency (RF) field and both static and fluctuating quadrupolar interactions. Spectra resulting from Fourier transformation of the evolutions of the on-resonance spin-locked magnetization into the various coherences display two satellite pairs and, in some cases, a central line. The central line is generally trimodal, consisting of a narrow component related to a slowly relaxing mode and two broad components pertaining to two faster relaxing modes. The rates of the fast modes are sensitive to slow molecular motion. Neither the amplitude nor the width of the narrow component is affected by the magnitude of the static coupling, whereas the corresponding features of the broad components depend in a rather complicated manner on the spin-lock field strength and static quadrupolar interaction. Under certain experimental conditions, the dependencies of the amplitudes on the dynamics are seen to vanish and the relaxation rates reduce to relatively simple expressions. One of the promising emerging features is the fact that the evolutions into the selectively detected quadrupolar spin polarization order and the rank-two double-quantum coherence do not exhibit a slowly relaxing mode and are particularly sensitive to slow molecular motion. Furthermore, these coherences can only be excited in the presence of a static coupling and this makes it possible to discern nuclei in anisotropic from those in isotropic environment. The feasibility of the spin-lock pulse sequences with limited RF power and a nonvanishing average electric field gradient has been demonstrated through experiments on sodium in a dense lyotropic DNA liquid crystal. PMID:11531352

  20. Impact of Quadrupolar Electrostatics on Atoms Adjacent to the Sigma-Hole in Condensed-Phase Simulations.

    PubMed

    El Hage, Krystel; Bereau, Tristan; Jakobsen, Sofie; Meuwly, Markus

    2016-07-12

    Halogenation is one of the cases for which advanced molecular simulation methods are mandatory for quantitative and predictive studies. The present work provides a systematic investigation of the importance of higher-order multipoles on specific sites of halobenzenes, other than the halogen, for static and dynamic properties in condensed-phase simulations. For that purpose, solute-solvent interactions using point charge (PC), multipole (MTP), and hybrid point charge/multipole (HYB) electrostatic models are analyzed in regions of halogen bonding and extended to regions of π orbitals of phenyl carbons. Using molecular dynamics simulations and quantum chemical methods, it is found that the sigma-hole does not only affect the halogen and the carbon bound to it but its effect extends to the carbons adjacent to the CX bond. This effect increases with the magnitude of the positive potential of the sigma-hole. With the MTP and HYB3 models, all hydration free energies of the PhX compounds are reproduced within 0.1 kcal/mol. Analysis of pair distribution functions and hydration free energies of halogenated benzenes provides a microscopic explanation why "point charge"-based representations with off-site charges fail in reproducing thermodynamic properties of the sigma-hole. Application of the hybrid models to study protein-ligand binding demonstrates both their accuracy and computational efficiency. PMID:27158892

  1. Multiferroics with spiral spin orders.

    PubMed

    Tokura, Yoshinori; Seki, Shinichiro

    2010-04-12

    Cross correlation between magnetism and electricity in a solid can host magnetoelectric effects, such as magnetic (electric) induction of polarization (magnetization). A key to attain the gigantic magnetoelectric response is to find the efficient magnetism-electricity coupling mechanisms. Among those, recently the emergence of spontaneous (ferroelectric) polarization in the insulating helimagnet or spiral-spin structure was unraveled, as mediated by the spin-exchange and spin-orbit interactions. The sign of the polarization depends on the helicity (spin rotation sense), while the polarization direction itself depends on further details of the mechanism and the underlying lattice symmetry. Here, we describe some prototypical examples of the spiral-spin multiferroics, which enable some unconventional magnetoelectric control such as the magnetic-field-induced change of the polarization direction and magnitude as well as the electric-field-induced change of the spin helicity and magnetic domain. PMID:20496385

  2. Magnetic ordering in the frustrated J1 - J2 Ising chain candidate BaNd2O4

    DOE PAGESBeta

    Aczel, Adam A.; Li, Ling; Garlea, Vasile O.; Yan, Jiaqiang; Weickert, Franziska; Jaime, M.; Maiorov, B.; Movshovich, R.; Civale, L.; Keppens, V.; et al

    2014-10-06

    The AR2O4 family (R = rare earth) has recently been attracting interest as a new series of frustrated magnets, with the magnetic R atoms forming zigzag chains running along the c axis. In this paper, we have investigated polycrystalline BaNd2O4 with a combination of magnetization, heat-capacity, and neutron powder diffraction measurements. Magnetic Bragg peaks are observed below TN = 1.7 K, and they can be indexed with a propagation vector of k = (0,1/2,1/2). The signal from magnetic diffraction is well described by long-range ordering of only one of the two types of Nd zigzag chains, with collinear up-up-down-down intrachainmore » spin configurations (double Néel state). Furthermore, low-temperature magnetization and heat-capacity measurements reveal two magnetic-field-induced spin transitions at 2.75 and 4 T for T = 0.46 K. The high-field phase is paramagnetic, while the intermediate-field state may arise from a spin transition of the long-range ordered Nd chains. Finally, one possible candidate for the field-induced ordered state corresponds to an up-up-down intrachain spin configuration, as predicted for a classical J1-J2 Ising chain with a double Néel ground state in zero field.« less

  3. First-Order Structural Change Accompanied by Yb Valence Transition in YbInCu4

    NASA Astrophysics Data System (ADS)

    Tsutsui, Satoshi; Sugimoto, Kunihisa; Tsunoda, Ryoma; Hirose, Yusuke; Mito, Takeshi; Settai, Rikio; Mizumaki, Masaichiro

    2016-06-01

    A diffraction experiment using high-energy X-rays was carried out on YbInCu4. Below the Yb valence transition temperature, the splitting of Bragg peaks was detected in high-order reflections. No superlattice reflections accompanying the valence ordering were found below the transition temperature. These experimental findings indicate that a structural change from a cubic structure to a tetragonal structure without valence ordering occurs at the transition temperature. Such a structural change free from any valence ordering is difficult to understand only in terms of Yb valence degrees of freedom. This means that the structural change may be related to electronic symmetries such as quadrupolar degrees of freedom as well as to the change in Yb valence.

  4. Order Up

    ERIC Educational Resources Information Center

    Gibeault, Michael

    2005-01-01

    Change orders. The words can turn the stomachs of administrators. Horror stories about change orders create fear and distrust among school officials, designers and builders. Can change orders be avoided? If car manufacturers can produce millions of intricately designed vehicles, why can't the same quality control be achieved on a construction…

  5. Magnetic Ordering-Induced Multiferroic Behavior in [CH3NH3][Co(HCOO)3] Metal-Organic Framework.

    PubMed

    Gómez-Aguirre, L Claudia; Pato-Doldán, Breogán; Mira, J; Castro-García, Socorro; Señarís-Rodríguez, María Antonia; Sánchez-Andújar, Manuel; Singleton, John; Zapf, Vivien S

    2016-02-01

    We present the first example of magnetic ordering-induced multiferroic behavior in a metal-organic framework magnet. This compound is [CH3NH3][Co(HCOO)3] with a perovskite-like structure. The A-site [CH3NH3](+) cation strongly distorts the framework, allowing anisotropic magnetic and electric behavior and coupling between them to occur. This material is a spin canted antiferromagnet below 15.9 K with a weak ferromagnetic component attributable to Dzyaloshinskii-Moriya (DM) interactions and experiences a discontinuous hysteretic magnetic-field-induced switching along [010] and a more continuous hysteresis along [101]. Coupling between the magnetic and electric order is resolved when the field is applied along this [101]: a spin rearrangement occurs at a critical magnetic field in the ac plane that induces a change in the electric polarization along [101] and [10-1]. The electric polarization exhibits an unusual memory effect, as it remembers the direction of the previous two magnetic-field pulses applied. The data are consistent with an inverse-DM mechanism for multiferroic behavior. PMID:26717023

  6. Magnetic ordering-induced multiferroic behavior in [CH3NH3][Co(HCOO)3] metal-organic framework.

    DOE PAGESBeta

    Gomez-Aguirre, Lilian Claudia; Zapf, Vivien S.; Pato-Doldan, Breogan; Mira, Jorge; Castro-Garcia, Socorro; Senaris-Rodriguez, Maria Antonia; Sanchez-Andujara, Manuel; Singleton, John

    2015-12-30

    Here, we present the first example of magnetic ordering-induced multiferroic behavior in a metal–organic framework magnet. This compound is [CH3NH3][Co(HCOO)3] with a perovskite-like structure. The A-site [CH3NH3]+ cation strongly distorts the framework, allowing anisotropic magnetic and electric behavior and coupling between them to occur. This material is a spin canted antiferromagnet below 15.9 K with a weak ferromagnetic component attributable to Dzyaloshinskii–Moriya (DM) interactions and experiences a discontinuous hysteretic magnetic-field-induced switching along [010] and a more continuous hysteresis along [101]. Coupling between the magnetic and electric order is resolved when the field is applied along this [101]: a spin rearrangementmore » occurs at a critical magnetic field in the ac plane that induces a change in the electric polarization along [101] and [10-1]. The electric polarization exhibits an unusual memory effect, as it remembers the direction of the previous two magnetic-field pulses applied. The data are consistent with an inverse-DM mechanism for multiferroic behavior.« less

  7. Order Nidovirales

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter, entitled "Order Nidovirales", is for inclusion in the Ninth Report of the International Committee on Taxonomy of Viruses (ICTV), to be published as both a single volume text and online. The chapter details the taxonomy of members of the Nidovirus order, including family Arteriviridae o...

  8. INFLUENCE OF DIFFERENT INCUBATOR MODELS ON MAGNETIC FIELD-INDUCED CHANGES IN NEURITE OUTGROWTH IN PC-12 CELLS

    EPA Science Inventory

    OBJECTIVE: Devise a method to standardize responses of cells to MF-exposure in different incubator environments. METHODS: We compared the cell responses to generated MF in a standard cell-culture incubator (Forma, model #3158) with cell responses to the same exposure when a mu-m...

  9. Magnetic-Field-Induced V-Shaped Quantized Conductance Staircase in a Double-Layer Quantum Point Contact

    SciTech Connect

    Lyo, S.K.

    1999-01-04

    We show that the low-temperature conductance (G) of a quantum point contact consisting of ballistic tunnel-coupled double-layer quantum well wires is modulated by an in-layer magnetic field B{sub {parallel}} perpendicular to the wires due to the anticrossing. In a system with a small g factor, B{sub {parallel}} creates a V-shaped quantum staircase for G, causing it to decrease in steps of 2e{sup 2}/{Dirac_h} to a minimum and then increase to a maximum value, where G may saturate or decrease again at higher B{sub {parallel}}'s. The effect of B{sub {parallel}}-induced mass enhancement and spin splitting is studied. The relevance of the results to recent data is discussed.

  10. Ab initio theory of magnetic-field-induced odd-frequency two-band superconductivity in MgB2

    NASA Astrophysics Data System (ADS)

    Aperis, Alex; Maldonado, Pablo; Oppeneer, Peter M.

    2015-08-01

    We develop the anisotropic Eliashberg framework for superconductivity in the presence of an applied magnetic field. Using as input the ab initio calculated electron and phonon band structures and electron-phonon coupling, we solve self-consistently the anisotropic Eliashberg equations for the archetypal superconductor MgB2. We find two self-consistent solutions, time-even two-band superconductivity, as well as unconventional time-odd s -wave spin triplet two-band superconductivity emerging with applied field. We provide the full momentum, frequency, and spin-resolved dependence and magnetic field-temperature phase diagrams of the time-even and time-odd superconducting pair amplitudes and predict fingerprints of this novel odd-frequency state in tunneling experiments.

  11. Anomalous hysteresis as evidence for a magnetic-field-induced chiral superconducting state in LiFeAs

    NASA Astrophysics Data System (ADS)

    Li, G.; Urbano, R. R.; Goswami, P.; Tarantini, C.; Lv, B.; Kuhns, P.; Reyes, A. P.; Chu, C. W.; Balicas, L.

    2013-01-01

    Magnetometry measurements in high-quality LiFeAs single crystals reveal a change in the sign of the magnetic hysteresis in the vicinity of the upper critical field Hc2, from a clear diamagnetic response dominated by the pinning of vortices to a considerably smaller net hysteretic response of opposite sign, which disappears at Hc2. If the diamagnetic response at high fields results from pinned vortices and associated screening supercurrents, this sign change must result from currents circulating in the opposite sense, which give rise to a small field-dependent magnetic moment below Hc2. This behavior seems to be extremely sensitive to the sample quality or stoichiometry, as we have observed it only in a few fresh crystals, which also display the de Haas van Alphen effect. We provide arguments against the surface superconductivity, the flux compression, and the random π junction scenarios, which have been previously put forward to explain a paramagnetic Meissner effect, below the lower critical field Hc1. The observed anomalous hysteresis at high fields will be compatible with the existence of chiral gap wave functions, which possess a field-dependent magnetic moment. Within a Landau-Ginzburg framework, we demonstrate how a (dx2-y2+idxy) or a (px+ipy) chiral superconducting component can be stabilized in the mixed state of s± superconductor, due to the combined effects of the magnetic field and the presence of competing pairing channels. The realization of a particular chiral pairing depends on the microscopic details of the strengths of the competing pairing channels.

  12. Magnetic-field-induced density of states in Mg B2 : Spin susceptibility measured by conduction-electron spin resonance

    NASA Astrophysics Data System (ADS)

    Simon, F.; Jánossy, A.; Fehér, T.; Murányi, F.; Garaj, S.; Forró, L.; Petrovic, C.; Bud'Ko, S.; Ribeiro, R. A.; Canfield, P. C.

    2005-07-01

    The magnetic-field dependence of the electron spin susceptibility χs was measured in the superconducting state of high-purity MgB2 fine powders from the intensity of the conduction-electron spin resonance at 3.8, 9.4, and 35GHz . The measurements confirm that a large part of the density of states is restored at low temperatures at fields below 1T in qualitative agreement with the closing of the π band gaps in the two-band model. However, the increase of χs with field and temperature is larger than expected from current superconductor models of MgB2 .

  13. Carrier relaxation in (In,Ga)As quantum dots with magnetic field-induced anharmonic level structure

    NASA Astrophysics Data System (ADS)

    Kurtze, H.; Bayer, M.

    2016-07-01

    Sophisticated models have been worked out to explain the fast relaxation of carriers into quantum dot ground states after non-resonant excitation, overcoming the originally proposed phonon bottleneck. We apply a magnetic field along the quantum dot heterostructure growth direction to transform the confined level structure, which can be approximated by a Fock-Darwin spectrum, from a nearly equidistant level spacing at zero field to strong anharmonicity in finite fields. This changeover leaves the ground state carrier population rise time unchanged suggesting that fast relaxation is maintained upon considerable changes of the level spacing. This corroborates recent models explaining the relaxation by polaron formation in combination with quantum kinetic effects.

  14. Magnetic field induced suppression of the forward bias current in Bi2Se3/Si Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Jin, Haoming; Hebard, Arthur

    Schottky diodes formed by van der Waals bonding between freshly cleaved flakes of the topological insulator Bi2Se3 and doped silicon substrates show electrical characteristics in good agreement with thermionic emission theory. The motivation is to use magnetic fields to modulate the conductance of the topologically protected conducting surface state. This surface state in close proximity to the semiconductor surface may play an important role in determining the nature of the Schottky barrier. Current-voltage (I-V) and capacitance-voltage (C-V) characteristics were obtained for temperatures in the range 50-300 K and magnetic fields, both perpendicular and parallel to the interface, as high as 7 T. The I-V curve shows more than 6 decades linearity on semi-logarithmic plots, allowing extraction of parameters such as ideality (η), zero-voltage Schottky barrier height (SBH), and series resistance (Rs). In forward bias we observe a field-induced decrease in current which becomes increasingly more pronounced at higher voltages and lower temperature, and is found to be correlated with changes in Rs rather than other barrier parameters. A comparison of changes in Rs in both field direction will be made with magnetoresistance in Bi2Se3 transport measurement. The work is supported by NSF through DMR 1305783.

  15. Resonant alteration of propagation in guiding structures with complex Robin parameter and its magnetic-field-induced restoration

    SciTech Connect

    Olendski, O.

    2011-06-15

    Highlights: > Solutions of the wave equation are analyzed for the confined circular geometry with complex Robin boundary conditions. > Sharp extremum is found in the energy dependence on the imaginary part of the extrapolation length. > Nonzero real part of the Robin length or/and magnetic field wipe out the resonance. - Abstract: Solutions of the scalar Helmholtz wave equation are derived for the analysis of the transport and thermodynamic properties of the two-dimensional disk and three-dimensional infinitely long straight wire in the external uniform longitudinal magnetic field B under the assumption that the Robin boundary condition contains extrapolation length {Lambda} with nonzero imaginary part {Lambda}{sub i}. As a result of this complexity, the self-adjointness of the Hamiltonian is lost, its eigenvalues E become complex too and the discrete bound states of the disk characteristic for the real {Lambda} turn into the corresponding quasibound states with their lifetime defined by the eigenenergies imaginary parts E{sub i}. Accordingly, the longitudinal flux undergoes an alteration as it flows along the wire with its attenuation/amplification being E{sub i}-dependent too. It is shown that, for zero magnetic field, the component E{sub i} as a function of the Robin imaginary part exhibits a pronounced sharp extremum with its magnitude being the largest for the zero real part {Lambda}{sub r} of the extrapolation length. Increasing magnitude of {Lambda}{sub r} quenches the E{sub i} - {Lambda}{sub i} resonance and at very large {Lambda}{sub r} the eigenenergies E approach the asymptotic real values independent of {Lambda}{sub i}. The extremum is also wiped out by the magnetic field when, for the large B, the energies tend to the Landau levels. Mathematical and physical interpretations of the obtained results are provided; in particular, it is shown that the finite lifetime of the disk quasibound states stems from the {Lambda}{sub i}-induced currents flowing through the sample boundary. Possible experimental tests of the calculated effect are discussed; namely, it is argued that it can be observed in superconductors by applying to them the external electric field E normal to the surface.

  16. High Domain Wall Velocity at Zero Magnetic Field Induced by Low Current Densities in Spin Valve Nanostripes

    NASA Astrophysics Data System (ADS)

    Pizzini, Stefania; Uhlíř, Vojtěch; Vogel, Jan; Rougemaille, Nicolas; Laribi, Sana; Cros, Vincent; Jiménez, Erika; Camarero, Julio; Tieg, Carsten; Bonet, Edgar; Bonfim, Marlio; Mattana, Richard; Deranlot, Cyrile; Petroff, Frédéric; Ulysse, Christian; Faini, Giancarlo; Fert, Albert

    2009-02-01

    Current-induced magnetic domain wall motion at zero magnetic field is observed in the permalloy layer of a spin-valve-based nanostripe using photoemission electron microscopy. The domain wall movement is hampered by pinning sites, but in between them high domain wall velocities (exceeding 150 m/s) are obtained for current densities well below 1012 A/m2, suggesting that these trilayer systems are promising for applications in domain wall devices in case of well controlled pinning positions. Vertical spin currents in these structures provide a potential explanation for the increase in domain wall velocity at low current densities.

  17. Polymeric Nanocomposite that Mimics in vivo ECM Topography in Tissue using Magnetic Field-induced Particle Self-assembly

    NASA Astrophysics Data System (ADS)

    Kim, Jiyun; Staunton, Jack; Tanner, Kandice

    3D biomaterials that mimic a certain physical or chemical aspect of cellular environment have been used to recreate the diversity of the tissue microenvironment. Especially, physical characteristics of these materials such as topography, dimension and stiffness, have known to have crucial effects on cell fate and cell malignancy. Here, we propose a technique that is able to create diverse topographies in 3D polymeric scaffold for the purpose of mimicking the structural aspect of tissue microenvironment. To achieve this, we exploit the magnetic field-directed assembly of super paramagnetic particles to fabricate chain-distributed architecture such that we can study the effects of extracellular matrix (ECM) topography on cell behavior. First, we chemically cross-link proteins including fibronectin, laminin and bovine albumin serum on the surface of magnetic particles to make the building blocks for artificial topography. Then, we assemble these particles by applying the parallel magnetic field in a surrogate polymeric matrix and solidify the matrix to maintain the assembled topography. Using this simple technique, we patterned diverse topographies in 3D including globular, fibril or interfaced architectures without chafing other material characteristics of the scaffold matrix, such as stiffness and molecular diffusion. We demonstrated that the fibril architecture guilds the dendritic extension of fibroblasts and neuron-like cells, compared to the cells grown in the globular architecture lacking anisotropic guidance cues.

  18. Magnetic-field-induced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength

    NASA Astrophysics Data System (ADS)

    Raaijmakers, A. J. E.; Raaymakers, B. W.; Lagendijk, J. J. W.

    2008-02-01

    Several institutes are currently working on the development of a radiotherapy treatment system with online MR imaging (MRI) modality. The main difference between their designs is the magnetic field strength of the MRI system. While we have chosen a 1.5 Tesla (T) magnetic field strength, the Cross Cancer Institute in Edmonton will be using a 0.2 T MRI scanner and the company Viewray aims to use 0.3 T. The magnetic field strength will affect the severity of magnetic field dose effects, such as the electron return effect (ERE): considerable dose increase at tissue air boundaries due to returning electrons. This paper has investigated how the ERE dose increase depends on the magnetic field strength. Therefore, four situations where the ERE occurs have been simulated: ERE at the distal side of the beam, the lateral ERE, ERE in cylindrical air cavities and ERE in the lungs. The magnetic field comparison values were 0.2, 0.75, 1.5 and 3 T. Results show that, in general, magnetic field dose effects are reduced at lower magnetic field strengths. At the distal side, the ERE dose increase is largest for B = 0.75 T and depends on the irradiation field size for B = 0.2 T. The lateral ERE is strongest for B = 3 T but shows no effect for B = 0.2 T. Around cylindrical air cavities, dose inhomogeneities disappear if the radius of the cavity becomes small relative to the in-air radius of the secondary electron trajectories. At larger cavities (r > 1 cm), dose inhomogeneities exist for all magnetic field strengths. In water-lung-water phantoms, the ERE dose increase takes place at the water-lung transition and the dose decreases at the lung-water transition, but these effects are minimal for B = 0.2 T. These results will contribute to evaluating the trade-off between magnetic field dose effects and image quality of MR-guided radiotherapy systems.

  19. Magnetic-field-induced effects in the electronic structure of itinerant d- and f-metal systems

    NASA Astrophysics Data System (ADS)

    Grechnev, G. E.

    2009-08-01

    A paramagnetic response of transition metals and itinerant d- and f-metal compounds in an external magnetic field is studied by employing ab initio full-potential LMTO method in the framework of the local spin density approximation. Within this method the anisotropy of the magnetic susceptibility in hexagonal close-packed transition metals is evaluated for the first time. This anisotropy is owing to the orbital Van Vleck-like paramagnetic susceptibility, which is revealed to be substantial in transition-metal systems due to hybridization effects in the electronic structure. It is demonstrated that compounds TiCo, Ni3Al, YCo2, CeCo2, YNi5, LaNi5, and CeNi5 are strong paramagnets close to the quantum critical point. For these systems the Stoner approximation underestimates the spin susceptibility, whereas the calculated field-induced spin moments provide a good description of the large paramagnetic susceptibilities and magnetovolume effects. It is revealed that an itinerant description of hybridized f electrons produces magnetic properties of the compounds CeCo2, CeNi5, UAl3, UGa3, USi3, and UGe3 in close agreement with experiment. In the uranium compounds UX3 the strong spin-orbit coupling together with hybridization effects give rise to peculiar magnetic states in which the field-induced spin moments are antiparallel to the external field, and the magnetic response is dominated by the orbital contribution.

  20. Specific heat and entropy change at the first order phase transition of La(Fe-Mn-Si)13-H compounds

    NASA Astrophysics Data System (ADS)

    Basso, Vittorio; Küpferling, Michaela; Curcio, Carmen; Bennati, Cecilia; Barzca, Alexander; Katter, Matthias; Bratko, Milan; Lovell, Edmund; Turcaud, Jeremy; Cohen, Lesley F.

    2015-08-01

    In this paper, we present the results of an experimental investigation on the magnetocaloric properties of hydrogenated La(Fe-Mn-Si)13-H with Mn substituting Fe to finely tune the transition temperature. We measured the specific heat under magnetic field cp(H, T) and the magnetic field induced isothermal entropy change Δs(H, T) of a series of compounds by direct Peltier calorimetry. Results show that increasing Mn from 0.06 to 0.46 reduces the transition temperature from 339 K to 270 K whilst the total entropy change due to a 1.5 T field is depressed from 18.7 J kg-1 K-1 to 10.2 J kg-1 K-1 and the thermal hysteresis similarly is reduced from 1.5 K to zero. In the paper, we interpret the results in terms of a magnetic phase transition changing from the first to the second order with increasing Mn content, and we discuss the value of the results for magnetic cooling applications.

  1. Magnetic ordering-induced multiferroic behavior in [CH3NH3][Co(HCOO)3] metal-organic framework.

    SciTech Connect

    Gomez-Aguirre, Lilian Claudia; Zapf, Vivien S.; Pato-Doldan, Breogan; Mira, Jorge; Castro-Garcia, Socorro; Senaris-Rodriguez, Maria Antonia; Sanchez-Andujara, Manuel; Singleton, John

    2015-12-30

    Here, we present the first example of magnetic ordering-induced multiferroic behavior in a metal–organic framework magnet. This compound is [CH3NH3][Co(HCOO)3] with a perovskite-like structure. The A-site [CH3NH3]+ cation strongly distorts the framework, allowing anisotropic magnetic and electric behavior and coupling between them to occur. This material is a spin canted antiferromagnet below 15.9 K with a weak ferromagnetic component attributable to Dzyaloshinskii–Moriya (DM) interactions and experiences a discontinuous hysteretic magnetic-field-induced switching along [010] and a more continuous hysteresis along [101]. Coupling between the magnetic and electric order is resolved when the field is applied along this [101]: a spin rearrangement occurs at a critical magnetic field in the ac plane that induces a change in the electric polarization along [101] and [10-1]. The electric polarization exhibits an unusual memory effect, as it remembers the direction of the previous two magnetic-field pulses applied. The data are consistent with an inverse-DM mechanism for multiferroic behavior.

  2. Influence of Chirality in Ordered Block Copolymer Phases

    NASA Astrophysics Data System (ADS)

    Prasad, Ishan; Grason, Gregory

    2015-03-01

    Block copolymers are known to assemble into rich spectrum of ordered phases, with many complex phases driven by asymmetry in copolymer architecture. Despite decades of study, the influence of intrinsic chirality on equilibrium mesophase assembly of block copolymers is not well understood and largely unexplored. Self-consistent field theory has played a major role in prediction of physical properties of polymeric systems. Only recently, a polar orientational self-consistent field (oSCF) approach was adopted to model chiral BCP having a thermodynamic preference for cholesteric ordering in chiral segments. We implement oSCF theory for chiral nematic copolymers, where segment orientations are characterized by quadrupolar chiral interactions, and focus our study on the thermodynamic stability of bi-continuous network morphologies, and the transfer of molecular chirality to mesoscale chirality of networks. Unique photonic properties observed in butterfly wings have been attributed to presence of chiral single-gyroid networks, this has made it an attractive target for chiral metamaterial design.

  3. Magnetic ordering in the frustrated J1 - J2 Ising chain candidate BaNd2O4

    SciTech Connect

    Aczel, Adam A.; Li, Ling; Garlea, Vasile O.; Yan, Jiaqiang; Weickert, Franziska; Jaime, M.; Maiorov, B.; Movshovich, R.; Civale, L.; Keppens, V.; Mandrus, D.

    2014-10-06

    The AR2O4 family (R = rare earth) has recently been attracting interest as a new series of frustrated magnets, with the magnetic R atoms forming zigzag chains running along the c axis. In this paper, we have investigated polycrystalline BaNd2O4 with a combination of magnetization, heat-capacity, and neutron powder diffraction measurements. Magnetic Bragg peaks are observed below TN = 1.7 K, and they can be indexed with a propagation vector of k = (0,1/2,1/2). The signal from magnetic diffraction is well described by long-range ordering of only one of the two types of Nd zigzag chains, with collinear up-up-down-down intrachain spin configurations (double Néel state). Furthermore, low-temperature magnetization and heat-capacity measurements reveal two magnetic-field-induced spin transitions at 2.75 and 4 T for T = 0.46 K. The high-field phase is paramagnetic, while the intermediate-field state may arise from a spin transition of the long-range ordered Nd chains. Finally, one possible candidate for the field-induced ordered state corresponds to an up-up-down intrachain spin configuration, as predicted for a classical J1-J2 Ising chain with a double Néel ground state in zero field.

  4. Second order optical nonlinearity in silicon by symmetry breaking

    NASA Astrophysics Data System (ADS)

    Cazzanelli, Massimo; Schilling, Joerg

    2016-03-01

    Although silicon does not possess a dipolar bulk second order nonlinear susceptibility due to its centro-symmetric crystal structure, in recent years several attempts were undertaken to create such a property in silicon. This review presents the different sources of a second order susceptibility (χ(2)) in silicon and the connected second order nonlinear effects which were investigated up to now. After an introduction, a theoretical overview discusses the second order nonlinearity in general and distinguishes between the dipolar contribution—which is usually dominating in non-centrosymmetric structures—and the quadrupolar contribution, which even exists in centro-symmetric materials. Afterwards, the classic work on second harmonic generation from silicon surfaces in reflection measurements is reviewed. Due to the abrupt symmetry breaking at surfaces and interfaces locally a dipolar second order susceptibility appears, resulting in, e.g., second harmonic generation. Since the bulk contribution is usually small, the study of this second harmonic signal allows a sensitive observation of the surface/interface conditions. The impact of covering films, strain, electric fields, and defect states at the interfaces was already investigated in this way. With the advent of silicon photonics and the search for ever faster electrooptic modulators, the interest turned to the creation of a dipolar bulk χ(2) in silicon. These efforts have been focussing on several experiments applying an inhomogeneous strain to the silicon lattice to break its centro-symmetry. Recent results suggesting the impact of electric fields which are exerted from fixed charges in adjacent covering layers are also included. After a subsequent summary on "competing" concepts using not Si but Si-related materials, the paper will end with some final conclusions, suggesting possible future research direction in this dynamically developing field.

  5. Impact of gravitational radiation higher order modes on single aligned-spin gravitational wave searches for binary black holes

    NASA Astrophysics Data System (ADS)

    Calderón Bustillo, Juan; Husa, Sascha; Sintes, Alicia M.; Pürrer, Michael

    2016-04-01

    Current template-based gravitational wave searches for compact binary coalescences use waveform models that omit the higher order modes content of the gravitational radiation emitted, considering only the quadrupolar (ℓ,|m |)=(2 ,2 ) modes. We study the effect of such omission for the case of aligned-spin compact binary coalescence searches for equal-spin (and nonspinning) binary black holes in the context of two versions of Advanced LIGO: the upcoming 2015 version, known as early Advanced LIGO (eaLIGO) and its zero-detuned high-energy power version, which we will refer to as Advanced LIGO (AdvLIGO). In addition, we study the case of a nonspinning search for initial LIGO (iLIGO). We do this via computing the effectualness of the aligned-spin SEOBNRv1 reduced order model waveform family, which only considers quadrupolar modes, toward hybrid post-Newtonian/numerical relativity waveforms which contain higher order modes. We find that for all LIGO versions losses of more than 10% of events occur in the case of AdvLIGO for mass ratio q ≥6 and total mass M ≥100 M⊙ due to the omission of higher modes, this region of the parameter space being larger for eaLIGO and iLIGO. Moreover, while the maximum event loss observed over the explored parameter space for AdvLIGO is of 15% of events, for iLIGO and eaLIGO, this increases up to (39,23)%. We find that omission of higher modes leads to observation-averaged systematic parameter biases toward lower spin, total mass, and chirp mass. For completeness, we perform a preliminar, nonexhaustive comparison of systematic biases to statistical errors. We find that, for a given signal-to-noise ratio, systematic biases dominate over statistical errors at much lower total mass for eaLIGO than for AdvLIGO.

  6. Hyperfine interactions in titanates: Study of orbital ordering and local magnetic properties

    SciTech Connect

    Agzamova, P. A. Leskova, Yu. V.; Nikiforov, A. E.

    2013-05-15

    Hyperfine magnetic fields induced on the nuclei of nonmagnetic ions {sup 139}La and {sup 89}Y in LaTiO{sub 3} and YTiO{sub 3}, respectively, have been microscopically calculated. The dependence of the hyperfine fields on the orbital and magnetic structures of the compounds under study has been analyzed. The comparative analysis of the calculated and known experimental data confirms the existence of the static orbital structure in lanthanum and yttrium titanates.

  7. Variable Order and Distributed Order Fractional Operators

    NASA Technical Reports Server (NTRS)

    Lorenzo, Carl F.; Hartley, Tom T.

    2002-01-01

    Many physical processes appear to exhibit fractional order behavior that may vary with time or space. The continuum of order in the fractional calculus allows the order of the fractional operator to be considered as a variable. This paper develops the concept of variable and distributed order fractional operators. Definitions based on the Riemann-Liouville definitions are introduced and behavior of the operators is studied. Several time domain definitions that assign different arguments to the order q in the Riemann-Liouville definition are introduced. For each of these definitions various characteristics are determined. These include: time invariance of the operator, operator initialization, physical realization, linearity, operational transforms. and memory characteristics of the defining kernels. A measure (m2) for memory retentiveness of the order history is introduced. A generalized linear argument for the order q allows the concept of "tailored" variable order fractional operators whose a, memory may be chosen for a particular application. Memory retentiveness (m2) and order dynamic behavior are investigated and applications are shown. The concept of distributed order operators where the order of the time based operator depends on an additional independent (spatial) variable is also forwarded. Several definitions and their Laplace transforms are developed, analysis methods with these operators are demonstrated, and examples shown. Finally operators of multivariable and distributed order are defined in their various applications are outlined.

  8. A spherical cavity model for quadrupolar dielectrics.

    PubMed

    Dimitrova, Iglika M; Slavchov, Radomir I; Ivanov, Tzanko; Mosbach, Sebastian

    2016-03-21

    The dielectric properties of a fluid composed of molecules possessing both dipole and quadrupole moments are studied based on a model of the Onsager type (molecule in the centre of a spherical cavity). The dielectric permittivity ε and the macroscopic quadrupole polarizability αQ of the fluid are related to the basic molecular characteristics (molecular dipole, polarizability, quadrupole, quadrupolarizability). The effect of αQ is to increase the reaction field, to bring forth reaction field gradient, to decrease the cavity field, and to bring forth cavity field gradient. The effects from the quadrupole terms are significant in the case of small cavity size in a non-polar liquid. The quadrupoles in the medium are shown to have a small but measurable effect on the dielectric permittivity of several liquids (Ar, Kr, Xe, CH4, N2, CO2, CS2, C6H6, H2O, CH3OH). The theory is used to calculate the macroscopic quadrupolarizabilities of these fluids as functions of pressure and temperature. The cavity radii are also determined for these liquids, and it is shown that they are functions of density only. This extension of Onsager's theory will be important for non-polar solutions (fuel, crude oil, liquid CO2), especially at increased pressures. PMID:27004882

  9. XMM Observations of Two Quadrupolar Outflows

    NASA Astrophysics Data System (ADS)

    Simon, Theodore

    2009-03-01

    X-ray images of two small dark clouds, L1455 and L723, have been obtained with the EPIC cameras on board the XMM-Newton telescope. Both regions contain multiple independent but overlapping bipolar flows in high-velocity CO, a collection of Herbig-Haro objects, and a number of filaments and knots of H2 emission. The field of view in each cloud was centered on the confluence of the nearly orthogonal CO flows. More than three dozen compact X-ray sources were detected. However, the Class 0/I protostars thought to be the driving sources of the flows in both clouds were not detected. Strong emission was observed from RNO 15, an optically visible, nebulous T Tauri star in the dense core of L1455. A thermal plasma model for the X-ray spectrum of RNO 15 gave a luminosity of L X ~ 1031.2 erg s-1. The heavily reddened Class II star L1455 IRS 5 in the same region was detected as a weak X-ray source. No emission was detected from IRS 1 or IRS 4, which have been suggested as the launch sites for separate outflows in L1455. X-ray emission was observed from IRAS 19156+1906 in L723. The thermal radio source VLA 2, which is offset ~10'' east of the IRAS position and is considered the most likely energy source for the strong east-west flow in L723, was not detected. The source of the more narrowly collimated north-south flow in L723 is unknown but may be an embedded infrared object at the X-ray and IRAS position.

  10. A spherical cavity model for quadrupolar dielectrics

    NASA Astrophysics Data System (ADS)

    Dimitrova, Iglika M.; Slavchov, Radomir I.; Ivanov, Tzanko; Mosbach, Sebastian

    2016-03-01

    The dielectric properties of a fluid composed of molecules possessing both dipole and quadrupole moments are studied based on a model of the Onsager type (molecule in the centre of a spherical cavity). The dielectric permittivity ɛ and the macroscopic quadrupole polarizability αQ of the fluid are related to the basic molecular characteristics (molecular dipole, polarizability, quadrupole, quadrupolarizability). The effect of αQ is to increase the reaction field, to bring forth reaction field gradient, to decrease the cavity field, and to bring forth cavity field gradient. The effects from the quadrupole terms are significant in the case of small cavity size in a non-polar liquid. The quadrupoles in the medium are shown to have a small but measurable effect on the dielectric permittivity of several liquids (Ar, Kr, Xe, CH4, N2, CO2, CS2, C6H6, H2O, CH3OH). The theory is used to calculate the macroscopic quadrupolarizabilities of these fluids as functions of pressure and temperature. The cavity radii are also determined for these liquids, and it is shown that they are functions of density only. This extension of Onsager's theory will be important for non-polar solutions (fuel, crude oil, liquid CO2), especially at increased pressures.

  11. Investigation of Solute-Fiber Affinity and Orientational Ordering of Norbornadiene Interacting with Two-Polypeptide Chiral Liquid Crystalline Solvents by Natural Abundance Deuterium (NAD) NMR.

    PubMed

    Serhan, Zeinab; Aroulanda, Christie; Lesot, Philippe

    2016-08-01

    A prochiral bridged compound of C2v symmetry, the norbornadiene (NBD), oriented in a chiral liquid crystal composed of various mixtures of poly-γ-benzyl-l-glutamate (PBLG) and poly-ε-carboxy-l-lysine (PCBLL), two chiral homopolypeptides, is investigated using natural abundance deuterium 2D-NMR (NAD 2D-NMR) spectroscopy. In such chiral oriented solvents, enantiotopic directions are spectrally nonequivalent, and two distinct (2)H quadrupolar doublets associated with enantioisotopomeric pairs of NBD are detected. As the two homopolypeptides have the same absolute configuration but distinct chemical functions in their side chains, the variation of residual quadrupolar couplings (RQC's) allows the determination of the relative solute-fiber affinities toward the two polypeptides in these lyotropic bipolymeric systems. Besides the experimental measurement of RQC's and the determination of their signs at each inequivalent (2)H site, the elements of the second-rank order tensor, Sαβ, are calculated by assuming a modeled structure. The variations of RQC's and diagonalized order parameters, Sα'α', are followed versus the relative proportion of two polypeptides in the chiral oriented mixture. The influence of the solute mass fraction in the two-homopolypeptide oriented samples is also examined as well as the case of homogeneous and uniform achiral mesophases "PBG-PCBL" made of two pairs of mirror-image homopolypeptides (PBLG/PBDG and PCBLL/PCBDL). In the latter, the solute ordering is modulated by the proportion of each type of homopolypeptide (chemical nature and absolute configuration), leading to eliminate the enantiodiscrimination mechanisms on the average. In the frame of a model, new insights on the solute-homopolypeptide fiber interactions are discussed. PMID:27383731

  12. A model of orientational ordering in phosphatidylcholine bilayers based on conformational analysis of the glycerol backbone region.

    PubMed Central

    Strenk, L M; Westerman, P W; Doane, J W

    1985-01-01

    Molecular and conformational ordering in aqueous multilamellar suspensions of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) have been examined by deuterium nuclear magnetic resonance (2H NMR) in the liquid crystalline (L alpha) phase. Motionally averaged quadrupolar splittings vQ from six sites in the vicinity of the glycerol backbone have been analyzed by a molecular frame and order matrix approach in which the usual assumption of a freely-rotating molecule is not invoked. By assuming a relatively rigid glycerol backbone region, the six vQ values are found to be consistent with a conformation of the glycerol backbone that is almost identical to that of one of the two structures in crystalline DMPC dihydrate (Pearson, R. H., and I. Pascher, 1979, Nature (Lond.) 281: 499-501). The orientation of the most-ordered axis of the DMPC molecule is found to be tilted at an angle of 27 +/- 2 degrees with respect to the long axis of the sn-1 chain in its extended all trans conformation. The ordering of the most ordered molecular axis with respect to the bilayer normal is expressed by an order parameter of Szz approximately equal to 0.6 +/- 0.1, consistent with values in analogous thermotropic liquid crystals. PMID:4074836

  13. Magnetic Field Induced Charged Exciton Studies in a GaAs/Al(0.3)Ga(0.7)As Single Heterojunction

    SciTech Connect

    Kim, Yongmin; Munteanu, F.M.; Perry, C.H.; Reno, J.L.; Rickel, D.G.; Simmons, J.A.

    1999-05-25

    The magnetophotoluminescence (MPL) behavior of a GaAs/Al0.3Ga0.7As single heterojunction has been investigated to 60T. We observed negatively charged singlet and triplet exciton states that are formed at high magnetic fields beyond the {nu}=l quantum Hall state. The variation of the charged exciton binding energies are in good agreement with theoretical predictions. The MPL transition intensities for these states showed intensity variations (maxima and minima) at the {nu}=l/3 and 1/5 fractional quantum Hall (FQH) state as a consequence of a large reduction of electron-hole screening at these filling factors.

  14. Absence of Magnetic-Field-Induced Effects in the Mid-infrared Transmission of La2−xSrxCuO4 Thin Films

    SciTech Connect

    Dordevic, S.V.; Gozar, A.; Kohlman, L.W.; Tung, L.C.; Wang, Y.-J.; Logvenov, G.; Bozovic, I.

    2009-04-01

    We report magnetotransmission measurements on a series of La{sub 2-x}Sr{sub x}CuO{sub 4} thin films. The measurements were performed in magnetic fields of 18 T, on films with doping levels of x = 0, 0.01, 0.03, 0.045, 0.06, 0.08, and 0.10. In addition, an optimally doped film (x = 0.16) was studied in magnetic fields up to 33 T, both above and below its superconducting critical temperature T{sub c} = 41 K. A combination of Gaussian and wavelet filtering was employed to improve the signal-to-noise ratio of the data. However, even after this procedure, we could not detect any field-induced changes of transmission in any of the studied samples. Our results therefore rule out a direct relation between intensity changes in mid-infrared charge excitations and a bosonic mode in the far infrared. We discuss these observations in the context of existing proposals regarding the nature of medium energy range excitations in the cuprates.

  15. Magnetic-field induced crossover of superconducting percolation regimes in the layered organic Mott system {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl.

    SciTech Connect

    Mueller, J.; Brandenberg, J.; Schlueter, J. A.; Materials Science Division; Max Planck Inst. for Chemical Physics of Solids

    2009-01-01

    Fluctuation spectroscopy is used to investigate the organic bandwidth-controlled Mott system {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl. We find evidence for percolative-type superconductivity in the spatially inhomogeneous coexistence region of antiferromagnetic insulating and superconducting states. When the superconducting transition is driven by a magnetic field, percolation seems to be dominated by instable superconducting clusters upon approaching T{sub c}(B) from above, before a 'classical' type of percolation is resumed at low fields, dominated by the fractional change of superconducting clusters. The 1/f noise is resolved into Lorentzian spectra in the crossover region, where the action of an individual fluctuator is enhanced, pointing to a mesoscopic phase separation.

  16. Magnetic-field-induced changes in superparamagnetic cluster dynamics in the martensitic phase of Ni43Co7Mn40Sn10

    NASA Astrophysics Data System (ADS)

    Kuhns, P. L.; Hoch, M. J. R.; Yuan, S.; Reyes, A. P.; Srivastava, V.; James, R. D.; Leighton, C.

    2016-06-01

    The off-stoichiometric Heusler alloys, such as Ni50Mn25+yX25-y (X = Sn, In, Ga, etc.), have been extensively investigated using a variety of experimental techniques to probe their interesting and potentially useful magnetic properties. Recent 55Mn nuclear magnetic resonance (NMR) experiments, carried out largely in zero field (ZF) and making use of the large internal hyperfine field at the nuclear sites, have demonstrated the power of this approach in determining the ground state magnetic characteristics of these materials. In particular, the results reveal that distinct nanoscale ferromagnetic and antiferromagnetic phases coexist. A key parameter used in interpreting the NMR data is the transverse relaxation time T2 which, inter alia, determines the NMR blocking temperature TBN M R of magnetic regions. The present experiments on a polycrystalline sample of a specific illustrative alloy, Ni43Co7Mn40Sn10, which has received considerable attention, show that the application of relatively small external fields, comparable to or greater than the local anisotropy field in the ferromagnetic cluster regions, produces dramatic changes in T2 and hence TBN M R . The experimental findings are discussed using an extended version of a recently proposed nanocluster model for superparamagnetic systems. It is demonstrated that the field and temperature induced changes in T2 provide a significant test of the model and lead to a notable advance in applying the NMR technique to the investigation of the magnetic properties of this type of alloy.

  17. Magnetic-Field-Induced Low-Energy Spin Excitations in YBa2Cu4O8 Measured by High Field Gd3+ Electron Spin Resonance

    NASA Astrophysics Data System (ADS)

    Fehér, Titusz; Jánossy, András; Oszlányi, Gábor; Simon, Ferenc; Dabrowski, Bogdan; Klamut, Piotr W.; Horvatić, Mladen; Williams, Grant V.

    2000-12-01

    We have measured the spin susceptibility, χs, of the CuO2 planes in the underdoped high Tc superconductor, YBa2Cu4O8 by Gd3+ electron spin resonance (ESR) in single crystals and aligned powders in fields up to 15.4 T. At low temperatures and high fields, χs is enhanced slightly in the B∥c orientation with respect to the B⊥c orientation. The enhancement at 15.4 T ( ~0.15Hc2) at 16 K ( 0.2 Tc) is small: approximately 10% of χs\\(Tc\\), suggesting that the second critical field of superconductivity, Hc2~100 T, would not suppress the pseudogap. This work demonstrates the potential of high field ESR in single crystals for studying high Tc superconductors.

  18. Magnetic-field-induced crossover from non-Fermi to Fermi liquid at the quantum critical point of YbCu5-xAux

    NASA Astrophysics Data System (ADS)

    Carretta, P.; Pasero, R.; Giovannini, M.; Baines, C.

    2009-01-01

    The temperature (T) dependence of the muon and C63u nuclear spin-lattice relaxation rates 1/T1 in YbCu4.4Au0.6 is reported over nearly four decades. It is shown that for T→0 1/T1 diverges following the behavior predicted by the self-consistent renormalization (SCR) theory for a ferromagnetic quantum critical point. On the other hand, the static uniform susceptibility χs is observed to diverge as T-2/3 and 1/T1T∝χs2 , a behavior which is not accounted for by SCR theory. The application of a magnetic field H is observed to induce a crossover to a Fermi-liquid behavior and for T→0 1/T1 is found to obey the scaling law 1/T1(H)=1/T1(0)[1+(μBH/kBT)2]-1 .

  19. In-plane magnetic-field-induced metal-insulator transition in (311)A GaAs two-dimensional hole systems probed by thermopower

    NASA Astrophysics Data System (ADS)

    Faniel, S.; Moldovan, L.; Vlad, A.; Tutuc, E.; Bishop, N.; Melinte, S.; Shayegan, M.; Bayot, V.

    2007-10-01

    We report thermopower measurements in dilute (311)A GaAs two-dimensional holes subjected to an in-plane magnetic field B that drives the system through a metal-insulator transition (MIT). The diffusion thermopower Sd decreases linearly with temperature at low B for both low-mobility [011¯] and high-mobility [2¯33] directions, as expected for metallic systems. At high B , in the insulating phase, Sd changes sign along [011¯] , while Sd drops to zero along [2¯33] . This behavior suggests that the system does not undergo any ground-state modification but, rather, that the apparent MIT transition is accompanied by a dramatic change in the dominant scattering mechanisms.

  20. Magnetic-field-induced squeezing effect at energies available at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Pang, Long-Gang; Endrődi, Gergely; Petersen, Hannah

    2016-04-01

    In off-central heavy-ion collisions, quark-gluon plasma (QGP) is exposed to the strongest magnetic fields ever created in the universe. Because of the paramagnetic nature of the QGP at high temperatures, the spatially inhomogeneous magnetic field configuration exerts an anisotropic force density that competes with the pressure gradients resulting from purely geometric effects. In this paper, we simulate (3+1)-dimensional ideal hydrodynamics with external magnetic fields to estimate the effect of this force density on the anisotropic expansion of the QGP in collisions at the Relativistic Heavy Ion Collider and at the Large Hadron Collider (LHC). While negligible for quickly decaying magnetic fields, we find that long-lived fields generate a substantial force density that suppresses the momentum anisotropy of the plasma by up to 20 % at the LHC energy and also leaves its imprint on the elliptic flow v2 of charged pions.

  1. Synthesis of oxime-based CO-releasing molecules, CORMs and their immobilization on maghemite nanoparticles for magnetic-field induced CO release.

    PubMed

    Meyer, Hajo; Brenner, Markus; Höfert, Simon-P; Knedel, Tim-O; Kunz, Peter C; Schmidt, Annette M; Hamacher, Alexandra; Kassack, Matthias U; Janiak, Christoph

    2016-05-01

    Oxime-based CO-releasing molecules (oximeCORMs) were immobilized with a catechol-modified backbone on maghemite iron oxide nanoparticles (IONPs) to give oximeCORM@IONP. The CO release from the free and immobilized oximeCORMs was measured using the standard myoglobin assay. The oximeCORM-nanoparticles were coated with dextran for improved water solubility and confined into an alginate shell for protection and separation from the surrounding myoglobin assay to allow for CO release studies by UV/Vis absorption without interference from highly-absorptive oximeCORM@IONP. Half-lifes of the oxime-based polymer-confined alginate@dextran@oximeCORM@IONPs were estimated at 20 °C to 814 ± 23 min, at 37 °C to 346 ± 83 min and at 50 °C to 73 ± 1 min. The alginate@dextran@oximeCORM@IONP composite showed a further decrease of the half-life of CO release to 153 ± 27 min at 37 °C through local magnetic heating of the susceptible iron oxide nanoparticles with application of an external alternating magnetic field (31.7 kA m(-1), 247 kHz, 39.9 mTesla). The activation energy for the CO release from molecular dicarbonylchlorido(imidazole-2-carbaldehydeoxime)(alkoxycarbonyl)ruthenium(ii) complexes is determined to be ∼100 kJ mol(-1) for five different imidazole-oxime derivatives. PMID:27048982

  2. Large remnant polarization and magnetic field induced destruction of cycloidal spin structure in Bi1-xLaxFeO3 (0 ≤ x ≤ 0.2)

    NASA Astrophysics Data System (ADS)

    Yin, L. H.; Yang, J.; Zhao, B. C.; Liu, Y.; Tan, S. G.; Tang, X. W.; Dai, J. M.; Song, W. H.; Sun, Y. P.

    2013-06-01

    We prepared a series of Bi1-xLaxFeO3 (0 ≤ x ≤ 0.2) ceramics with a sol-gel method and find that both the magnetization and dielectric constant show an abrupt anomaly near a critical field Hc, which is attributed to the destruction of the cycloidal antiferromagnetic spin structure. The critical field Hc decreases substantially from ˜20 T for the x = 0 sample [Y. F. Popov et al., JETP Lett. 57, 69 (1993)] to ˜2.8 T for the x = 0.17 sample and finally to 0 T for the x = 0.2 sample at room temperature (RT). It is also found that Hc increases with decreasing temperature. The variation of Hc with La substitution and temperature can be ascribed to the change in the magnetic anisotropy and isotropic superexchange interaction, respectively. We have also discussed the magnetodielectric effects in these samples in terms of the Ginzburg-Landau theory and the spin-phonon model. Moreover, increasing the doping level of La to 0.15 greatly improves the RT leakage-current and ferroelectric (FE) properties. A RT square-shaped FE hysteresis loop with remnant polarization (2Pr) as high as ˜64 μC/cm2 is obtained for the x = 0.15 sample. These results may be important for potential applications in BiFeO3-based magnetoelectric devices.

  3. Alternating Magnetic Field-Induced Hyperthermia Increases Iron Oxide Nanoparticle Cell Association/Uptake and Flux in Blood– Brain Barrier Models

    PubMed Central

    Dan, Mo; Bae, Younsoo; Pittman, Thomas A.

    2016-01-01

    Purpose Superparamagnetic iron oxide nanoparticles (IONPs) are being investigated for brain cancer therapy because alternating magnetic field (AMF) activates them to produce hyperthermia. For central nervous system applications, brain entry of diagnostic and therapeutic agents is usually essential. We hypothesized that AMF-induced hyperthermia significantly increases IONP blood–brain barrier (BBB) association/uptake and flux. Methods Cross-linked nanoassemblies loaded with IONPs (CNA-IONPs) and conventional citrate-coated IONPs (citrate-IONPs) were synthesized and characterized in house. CNA-IONP and citrate-IONP BBB cell association/uptake and flux were studied using two BBB Transwell® models (bEnd.3 and MDCKII cells) after conventional and AMF-induced hyperthermia exposure. Results AMF-induced hyperthermia for 0.5 h did not alter CNA-IONP size but accelerated citrate-IONP agglomeration. AMF-induced hyperthermia for 0.5 h enhanced CNA-IONP and citrate-IONP BBB cell association/uptake. It also enhanced the flux of CNA-IONPs across the two in vitro BBB models compared to conventional hyperthermia and normothermia, in the absence of cell death. Citrate-IONP flux was not observed under these conditions. AMF-induced hyperthermia also significantly enhanced paracellular pathway flux. The mechanism appears to involve more than the increased temperature surrounding the CNA-IONPs. Conclusions Hyperthermia induced by AMF activation of CNA-IONPs has potential to increase the BBB permeability of therapeutics for the diagnosis and therapy of various brain diseases. PMID:25377069

  4. Neutron diffraction study of magnetic field induced behavior in the heavy Fermion Ce3Co4Sn13

    SciTech Connect

    Christianson, Andrew D; Goremychkin, E. A.; Gardner, J. S.; Kang, H. J.; Chung, J.-H.; Manuel, P.; Thompson, J. D.; Sarrao, J. L.; Lawrence, J. M.

    2008-01-01

    The specific heat of Ce3Co4Sn13 exhibits a crossover from heavy Fermion behavior with antiferromagnetic correlations at low field to single impurity Kondo behavior above 2 T. We have performed neutron diffraction measurements in magnetic fields up to 6 Tesla on single crystal samples. The (001) position shows a dramatic increase in intensity in field which appears to arise from static polarization of the 4f level and which at 0.14 K also exhibits an anomaly near 2T reflecting the crossover to single impurity behavior.

  5. Pressure-magnetic field induced phase transformation in Ni{sub 46}Mn{sub 41}In{sub 13} Heusler alloy

    SciTech Connect

    Rama Rao, N. V. Manivel Raja, M.; Pandian, S.; Esakki Muthu, S.; Arumugam, S.

    2014-12-14

    The effect of hydrostatic pressure and magnetic field on the magnetic properties and phase transformation in Ni{sub 46}Mn{sub 41}In{sub 13} Heusler alloy was investigated. Pressure (P)-magnetic field (H)-temperature (T) phase diagram has been constructed from experimental results. In the P–T contour of the phase diagram, the slope of the austenite-martensite phase boundary line appears positive (dT/dP > 0), while it appears negative (dT/dH < 0) in the H–T contour. The results revealed that pressure and magnetic field have opposite effect on phase stabilization. The combined effect of pressure and magnetic field on martensitic transition has led to two important findings: (i) pressure dependent shift of austenite start temperature (A{sub s}) is higher when larger field is applied, and (ii) field dependent shift of A{sub s} is lowered when a higher pressure is applied. The pressure and magnetic field dependent shift observed in the martensitic transformation has been explained on the basis of thermodynamic calculations. Curie temperature of the phases was found to increase with pressure at a rate of 0.6 K/kbar.

  6. Order Theoretical Semantic Recommendation

    SciTech Connect

    Joslyn, Cliff A.; Hogan, Emilie A.; Paulson, Patrick R.; Peterson, Elena S.; Stephan, Eric G.; Thomas, Dennis G.

    2013-07-23

    Mathematical concepts of order and ordering relations play multiple roles in semantic technologies. Discrete totally ordered data characterize both input streams and top-k rank-ordered recommendations and query output, while temporal attributes establish numerical total orders, either over time points or in the more complex case of startend temporal intervals. But also of note are the fully partially ordered data, including both lattices and non-lattices, which actually dominate the semantic strcuture of ontological systems. Scalar semantic similarities over partially-ordered semantic data are traditionally used to return rank-ordered recommendations, but these require complementation with true metrics available over partially ordered sets. In this paper we report on our work in the foundations of partial order measurement in ontologies, with application to top-k semantic recommendation in workflows.

  7. Thermo-magnetic history effects in the giant magnetostriction across the first-order transition and minor hysteresis loops modeling in Fe0.955Ni0.045Rh alloy.

    PubMed

    Manekar, Meghmalhar; Sharma, V K; Roy, S B

    2012-05-30

    Results of temperature- and magnetic field-dependent strain measurements across the first-order antiferromagnetic to ferromagnetic phase transition in Fe(0.955)Ni(0.045)Rh are presented. Distinct thermal and magnetic field hystereses are observed in the measured strain across the phase transition. The minor hysteresis loops inside the hysteretic regime across the temperature-driven transition are modeled using the Preisach model of hysteresis. The applicability of the Preisach model to explain the general features of minor hysteresis loops is discussed for a disorder influenced first-order transition. The minor hysteresis loops show the property of retaining the memory of the starting or end point of the temperature cycle followed within the hysteretic region. A larger temperature excursion within the hysteretic region wipes out the memory of a smaller temperature cycle which contains one of the extrema of the larger cycle. The end-point memory and the wiping-out property of the minor hysteresis loops can be described quite well within the Preisach model, irrespective of the temperature history followed to reach a particular starting point. Thermo-magnetic history effects across the magnetic field-induced transition are explained, which will enable the choice of the starting point of an experimental cycle in the field-temperature phase space so as to achieve the desired functionality. Our results highlight the necessity to understand the influence of disorder on a first-order phase transition so as to achieve a repeatable performance of materials whose functionalities are based on such a transition. PMID:22543692

  8. Minimal Orderings Revisited

    SciTech Connect

    Peyton, B.W.

    1999-07-01

    When minimum orderings proved too difficult to deal with, Rose, Tarjan, and Leuker instead studied minimal orderings and how to compute them (Algorithmic aspects of vertex elimination on graphs, SIAM J. Comput., 5:266-283, 1976). This paper introduces an algorithm that is capable of computing much better minimal orderings much more efficiently than the algorithm in Rose et al. The new insight is a way to use certain structures and concepts from modern sparse Cholesky solvers to re-express one of the basic results in Rose et al. The new algorithm begins with any initial ordering and then refines it until a minimal ordering is obtained. it is simple to obtain high-quality low-cost minimal orderings by using fill-reducing heuristic orderings as initial orderings for the algorithm. We examine several such initial orderings in some detail.

  9. Order Parameters of a Transmembrane Helix in a Fluid Bilayer: Case Study of a WALP Peptide

    PubMed Central

    Holt, Andrea; Rougier, Léa; Réat, Valérie; Jolibois, Franck; Saurel, Olivier; Czaplicki, Jerzy; Killian, J. Antoinette; Milon, Alain

    2010-01-01

    Abstract A new solid-state NMR-based strategy is established for the precise and efficient analysis of orientation and dynamics of transmembrane peptides in fluid bilayers. For this purpose, several dynamically averaged anisotropic constraints, including 13C and 15N chemical shift anisotropies and 13C-15N dipolar couplings, were determined from two different triple-isotope-labeled WALP23 peptides (2H, 13C, and 15N) and combined with previously published quadrupolar splittings of the same peptide. Chemical shift anisotropy tensor orientations were determined with quantum chemistry. The complete set of experimental constraints was analyzed using a generalized, four-parameter dynamic model of the peptide motion, including tilt and rotation angle and two associated order parameters. A tilt angle of 21° was determined for WALP23 in dimyristoylphosphatidylcholine, which is much larger than the tilt angle of 5.5° previously determined from 2H NMR experiments. This approach provided a realistic value for the tilt angle of WALP23 peptide in the presence of hydrophobic mismatch, and can be applied to any transmembrane helical peptide. The influence of the experimental data set on the solution space is discussed, as are potential sources of error. PMID:20441750

  10. First-order inflation

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.

    1991-01-01

    In the original proposal, inflation occurred in the process of a strongly first-order phase transition. This model was soon demonstrated to be fatally flawed. Subsequent models for inflation involved phase transitions that were second-order, or perhaps weakly first-order; some even involved no phase transition at all. Recently the possibility of inflation during a strongly first-order phase transition has been revived. In this talk I will discuss some models for first-order inflation, and emphasize unique signatures that result if inflation is realized in a first-order transition. Before discussing first-order inflation, I will briefly review some of the history of inflation to demonstrate how first-order inflation differs from other models.

  11. First-order inflation

    SciTech Connect

    Kolb, E.W. Chicago Univ., IL . Enrico Fermi Inst.)

    1990-09-01

    In the original proposal, inflation occurred in the process of a strongly first-order phase transition. This model was soon demonstrated to be fatally flawed. Subsequent models for inflation involved phase transitions that were second-order, or perhaps weakly first-order; some even involved no phase transition at all. Recently the possibility of inflation during a strongly first-order phase transition has been revived. In this talk I will discuss some models for first-order inflation, and emphasize unique signatures that result in inflation is realized in a first-order transition. Before discussing first-order inflation, I will briefly review some of the history of inflation to demonstrate how first-order inflation differs from other models. 58 refs., 3 figs.

  12. Ferromagnetic Order, Strong Magnetocrystalline Anisotropy, and Magnetocaloric Effect in the Layered Telluride Fe(3-δ)GeTe2.

    PubMed

    Verchenko, Valeriy Yu; Tsirlin, Alexander A; Sobolev, Alexei V; Presniakov, Igor A; Shevelkov, Andrei V

    2015-09-01

    The ternary transition-metal compound Fe(3-δ)GeTe2 is formed for 0 < δ < 0.3. X-ray diffraction and Mössbauer spectroscopy reveal its layered crystal structure with occasional Fe vacancies in the Fe2 site, whereas no Fe atoms occupy the interlayer space, so that only van der Waals interactions exist between adjacent layers. We explore magnetic behavior and ensuing functional properties of Fe(2.9)GeTe2 via neutron diffraction, thermodynamic and transport measurements, Mössbauer spectroscopy, and electronic structure calculations. Below T(C) = 225 K, Fe(2.9)GeTe2 is ferromagnetically ordered with the magnetic moments of 1.95(5) and 1.56(4) μ(B) at T = 1.5 K, both directed along c, which is the magnetic easy axis. Electronic structure calculations confirm this magnetic structure and reveal a remarkably high easy-axis anisotropy of 4.2 meV/f.u. Mössbauer spectra reveal the magnetic ordering too, although a drastic influence of Fe vacancies on quadrupolar splittings and local magnetic fields has been observed. A moderate magnetocaloric effect with the magnetic entropy change upon the ferromagnetic ordering transition, -ΔS ∼ 1.1 J·kg(-1)·K(-1) at 5 T, is found. PMID:26267350

  13. Multiple ordering in magnetite.

    NASA Technical Reports Server (NTRS)

    Cullen, J. R.; Callen, E. R.

    1973-01-01

    Results of a self-consistent band calculation of the ground-state energy and charge orderings based on a tight-binding scheme in magnetite are presented. They show that below a critical (about 2.2) value of the ratio of interatomic Coulomb energy to bandwidth the lowest energy state has no order. Between this critical value and 2.5, the preferred state is multiply ordered.

  14. After order 636

    SciTech Connect

    Katz, M.G.

    1995-02-01

    Through its Order 636, the Federal Energy Regulatory Commission (FERC) completed a restructuring of the natural gas industry. The order severed the last links in the chain linking gas producers to pipeline companies to local gas distribution companies (LDCs) to customers. Before Order 636 took effect, many predicted electric power generation, particularly by cogenerators and independent power producers (IPPs), would be a major growth area for natural gas. In fact, what Order 636 has shown is, that timing is everything, and that it`s difficult to sort out the effect of one agent of change when many others are at work.

  15. Order, Disorder and Confinement

    SciTech Connect

    D'Elia, M.; Di Giacomo, A.; Pica, C.

    2006-01-12

    Studying the order of the chiral transition for Nf = 2 is of fundamental importance to understand the mechanism of color confinement. We present results of a numerical investigation on the order of the transition by use of a novel strategy in finite size scaling analysis. The specific heat and a number of susceptibilities are compared with the possible critical behaviours. A second order transition in the O(4) and O(2) universality classes are excluded. Substantial evidence emerges for a first order transition. Results are in agreement with those found by studying the scaling properties of a disorder parameter related to the dual superconductivity mechanism of color confinement.

  16. Bioregions and World Order.

    ERIC Educational Resources Information Center

    Breakthrough, 1985

    1985-01-01

    What bioregions can do to contribute to world order and security is discussed in this newsletter. A bioregion is defined as an identifiable geographical area of interacting life-systems that is relatively self-sustaining in the ever-renewing processes of nature. Articles included are: "Bioregionalism and World Order" (Gerald Mische); "Bioregions:…

  17. ASDC Order Tools

    Atmospheric Science Data Center

    2012-04-17

    ... users to search our data holdings without logging in to the system. The user, however, must log in before ordering the data. ... Reverb, developed by Earth Science Data and Information System (ESDIS), gives the user community an improved search and order ...

  18. Charge transport in charge-ordered layered crystals θ-(BEDT-TTF)2MZn(SCN)4 (M=Cs,Rb) : Effects of long-range Coulomb interaction and the Pauli exclusion principle

    NASA Astrophysics Data System (ADS)

    Takahide, Yamaguchi; Kimata, Motoi; Hazama, Kaori; Terashima, Taichi; Uji, Shinya; Konoike, Takako; Yamamoto, Hiroshi M.

    2010-06-01

    We have measured the current-voltage (I-V) characteristics, dielectric properties, and magnetoresistances of insulating layered organic crystals θ-(BEDT-TTF)2MZn(SCN)4 (M=Cs,Rb) , in which electron-electron Coulomb interactions are considered to induce charge ordering. The in-plane I-V characteristics follow the power law with a large exponent that exceeds 10 in the low-temperature limit. The nonlinear I-V characteristics are attributed to electric field induced unbinding of pairs of an electron and a hole that are thermally excited and attracted to each other due to two-dimensional long-range Coulomb interaction. The temperature and frequency dependences of the in-plane dielectric constant for M=Cs are explained by the polarization of the electron-hole bound pairs, consistently with the I-V characteristics. The large dielectric anisotropy ( ≈100 at 0.6 K) observed for M=Cs suggests two-dimensional long-range Coulomb interaction, which is also consistent with the explanation of the nonlinear I-V curves. The organic crystals have a large positive magnetoresistance ratio, e.g., ≈10000% for M=Cs in a magnetic field of 10 T at 0.1 K. The magnetoresistance is nearly independent of the magnetic field orientation despite the highly two-dimensional charge transport, indicating that it is electron-spin related. The magnetoresistance may be caused by magnetic field induced parallel alignment of spins of mobile and localized electrons, both in the highest occupied molecular orbital of a BEDT-TTF molecule, and by the resulting suppression of conduction due to the Pauli exclusion principle.

  19. Second order Standard Model

    NASA Astrophysics Data System (ADS)

    Espin, Johnny; Krasnov, Kirill

    2015-06-01

    It is known, though not commonly, that one can describe fermions using a second order in derivatives Lagrangian instead of the first order Dirac one. In this description the propagator is scalar, and the complexity is shifted to the vertex, which contains a derivative operator. In this paper we rewrite the Lagrangian of the fermionic sector of the Standard Model in such second order form. The new Lagrangian is extremely compact, and is obtained from the usual first order Lagrangian by integrating out all primed (or dotted) 2-component spinors. It thus contains just half of the 2-component spinors that appear in the usual Lagrangian, which suggests a new perspective on unification. We sketch a natural in this framework SU (2) × SU (4) ⊂ SO (9) unified theory.

  20. Court Ordered Desegregation

    ERIC Educational Resources Information Center

    Reber, Sarah J.

    2005-01-01

    The effect of the court ordered desegregation plans, on trends in segregation and white flight, are estimated. The effect of availability of school districts and other factors on the white flight across districts is also mentioned.

  1. 'Good palliative care' orders.

    PubMed

    Maddocks, I

    1993-01-01

    A Select Committee of the Parliament of South Australia, considering revisions to legislation governing care of the dying, did not support allowing doctors to assist suicide. They recommended that no liability attach to the provision of reasonable palliative care which happens to shorten life. The Committee affirmed the suggestion that positive open orders to provide 'good palliative care' should replace 'do not resuscitate' orders. PMID:7506978

  2. Arguments from Developmental Order.

    PubMed

    Stöckle-Schobel, Richard

    2016-01-01

    In this article, I investigate a special type of argument regarding the role of development in theorizing about psychological processes and cognitive capacities. Among the issues that developmental psychologists study, discovering the ontogenetic trajectory of mechanisms or capacities underpinning our cognitive functions ranks highly. The order in which functions are developed or capacities are acquired is a matter of debate between competing psychological theories, and also philosophical conceptions of the mind - getting the role and the significance of the different steps in this order right could be seen as an important virtue of such theories. Thus, a special kind of strategy in arguments between competing philosophical or psychological theories is using developmental order in arguing for or against a given psychological claim. In this article, I will introduce an analysis of arguments from developmental order, which come in two general types: arguments emphasizing the importance of the early cognitive processes and arguments emphasizing the late cognitive processes. I will discuss their role in one of the central tools for evaluating scientific theories, namely in making inferences to the best explanation. I will argue that appeal to developmental order is, by itself, an insufficient criterion for theory choice and has to be part of an argument based on other core explanatory or empirical virtues. I will end by proposing a more concerted study of philosophical issues concerning (cognitive) development, and I will present some topics that also pertain to a full-fledged 'philosophy of development.' PMID:27242648

  3. Birth Order and Psychopathology

    PubMed Central

    Risal, Ajay; Tharoor, Hema

    2012-01-01

    Context: Ordinal position the child holds within the sibling ranking of a family is related to intellectual functioning, personality, behavior, and development of psychopathology. Aim: To study the association between birth order and development of psychopathology in patients attending psychiatry services in a teaching hospital. Settings and Design: Hospital-based cross-sectional study. Materials and Methods: Retrospective file review of three groups of patients was carried out. Patient-related variables like age of onset, birth order, family type, and family history of mental illness were compared with psychiatry diagnosis (ICD-10) generated. Statistical Analysis: SPSS 13; descriptive statistics and one-way analysis of variance (ANOVA) were used. Results: Mean age of onset of mental illness among the adult general psychiatry patients (group I, n = 527) was found to be 33.01 ± 15.073, while it was 11.68 ± 4.764 among the child cases (group II, n = 47) and 26.74 ± 7.529 among substance abuse cases (group III, n = 110). Among group I patients, commonest diagnosis was depression followed by anxiety and somatoform disorders irrespective of birth order. Dissociative disorders were most prevalent in the first born child (36.7%) among group II patients. Among group III patients, alcohol dependence was maximum diagnosis in all birth orders. Conclusions: Depression and alcohol dependence was the commonest diagnosis in adult group irrespective of birth order. PMID:24479023

  4. Arguments from Developmental Order

    PubMed Central

    Stöckle-Schobel, Richard

    2016-01-01

    In this article1, I investigate a special type of argument regarding the role of development in theorizing about psychological processes and cognitive capacities. Among the issues that developmental psychologists study, discovering the ontogenetic trajectory of mechanisms or capacities underpinning our cognitive functions ranks highly. The order in which functions are developed or capacities are acquired is a matter of debate between competing psychological theories, and also philosophical conceptions of the mind – getting the role and the significance of the different steps in this order right could be seen as an important virtue of such theories. Thus, a special kind of strategy in arguments between competing philosophical or psychological theories is using developmental order in arguing for or against a given psychological claim. In this article, I will introduce an analysis of arguments from developmental order, which come in two general types: arguments emphasizing the importance of the early cognitive processes and arguments emphasizing the late cognitive processes. I will discuss their role in one of the central tools for evaluating scientific theories, namely in making inferences to the best explanation. I will argue that appeal to developmental order is, by itself, an insufficient criterion for theory choice and has to be part of an argument based on other core explanatory or empirical virtues. I will end by proposing a more concerted study of philosophical issues concerning (cognitive) development, and I will present some topics that also pertain to a full-fledged ‘philosophy of development.’ PMID:27242648

  5. Concomitant Ordering and Symmetry Lowering

    ERIC Educational Resources Information Center

    Boo, William O. J.; Mattern, Daniell L.

    2008-01-01

    Examples of concomitant ordering include magnetic ordering, Jahn-Teller cooperative ordering, electronic ordering, ionic ordering, and ordering of partially-filled sites. Concomitant ordering sets in when a crystal is cooled and always lowers the degree of symmetry of the crystal. Concomitant ordering concepts can also be productively applied to…

  6. Land and World Order.

    ERIC Educational Resources Information Center

    Mische, Patricia, Ed.; And Others

    1982-01-01

    The papers in this publication discuss the land and how what happens to the land affects us. The publication is one in a series of monographs that examine the linkages between local and global concerns and explore alternative world futures. Examples of topics discussed in the papers follow. The paper "Land and World Order" examines implications of…

  7. The Order Pseudonocardiales

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Order Pseudonocardiales is made of up a single family Pseudonocardiaceae which forms a distinct cluster between the Frankineae and Streptomycineae when members of the taxa are subjected to 16S rRNA gene phylogenetic analysis. The family contains 26 genera including Pseudonocardia, Actinoalloteic...

  8. Memory for Serial Order.

    ERIC Educational Resources Information Center

    Lewandowsky, Stephan; Murdock, Bennet B., Jr.

    1989-01-01

    An extension to Murdock's Theory of Distributed Associative Memory, based on associative chaining between items, is presented. The extended theory is applied to several serial order phenomena, including serial list learning, delayed recall effects, partial report effects, and buildup and release from proactive interference. (TJH)

  9. The Birth Order Puzzle.

    ERIC Educational Resources Information Center

    Zajonc, R. B.; And Others

    1979-01-01

    Discusses the controversy of the relationship between birth order and intellectual performance through a detailed evaluation of the confluence model which assumes that the rate of intellectual growth is a function of the intellectual environment within the family and associated with the special circumstances of last children. (CM)

  10. Birth Order Debate Resolved?

    ERIC Educational Resources Information Center

    Zajonc, R. B.

    2001-01-01

    Critiques Rodgers et al.'s June 2000 research on the relation between birth order and intelligence, which suggests that it is a methodological illusion. Explains how the intellectual environment and the teaching function (whereby older children tutor younger ones) contribute to the growth of intellectual maturity, the first negatively and the…

  11. Order Lepidoptera Linnaeus, 1758.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Based on two recent molecular analyses, augmented by the discovery of several published or unpublished novel morphological synapomorphies, a new classification is proposed for the order Lepidoptera. The new classification is more consistent with our growing knowledge of the phylogeny of the group an...

  12. Education and World Order

    ERIC Educational Resources Information Center

    Jones, Phillip W.

    2007-01-01

    The impact on educational analysis of mainstream international relations (IR) theories is yet to realize its full potential. The problem of education in relation to the construction of world order is considered in relation to core developments in IR theory since the Second World War. In particular, the global architecture of education is seen as a…

  13. Competing Orders and Anomalies.

    PubMed

    Moon, Eun-Gook

    2016-01-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation "laws" could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the 't Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

  14. Audiotactile temporal order judgments.

    PubMed

    Zampini, Massimiliano; Brown, Timothy; Shore, David I; Maravita, Angelo; Röder, Brigitte; Spence, Charles

    2005-03-01

    We report a series of three experiments in which participants made unspeeded 'Which modality came first?' temporal order judgments (TOJs) to pairs of auditory and tactile stimuli presented at varying stimulus onset asynchronies (SOAs) using the method of constant stimuli. The stimuli were presented from either the same or different locations in order to explore the potential effect of redundant spatial information on audiotactile temporal perception. In Experiment 1, the auditory and tactile stimuli had to be separated by nearly 80 ms for inexperienced participants to be able to judge their temporal order accurately (i.e., for the just noticeable difference (JND) to be achieved), no matter whether the stimuli were presented from the same or different spatial positions. More experienced psychophysical observers (Experiment 2) also failed to show any effect of relative spatial position on audiotactile TOJ performance, despite having much lower JNDs (40 ms) overall. A similar pattern of results was found in Experiment 3 when silent electrocutaneous stimulation was used rather than vibrotactile stimulation. Thus, relative spatial position seems to be a less important factor in determining performance for audiotactile TOJ than for other modality pairings (e.g., audiovisual and visuotactile). PMID:15698825

  15. Competing Orders and Anomalies

    NASA Astrophysics Data System (ADS)

    Moon, Eun-Gook

    2016-08-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.

  16. Competing Orders and Anomalies

    PubMed Central

    Moon, Eun-Gook

    2016-01-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

  17. Localization protected quantum order

    NASA Astrophysics Data System (ADS)

    Nandkishore, Rahul

    2015-03-01

    Many body localization occurs in isolated quantum systems, usually with strong disorder, and is marked by absence of dissipation, absence of thermal equilibration, and a memory of the initial conditions that survives in local observables for arbitrarily long times. The many body localized regime is a non-equilibrium, strongly disordered, non-self averaging regime that presents a new frontier for quantum statistical mechanics. In this talk, I point out that there exists a vast zoo of correlated many body localized states of matter, which may be classified using familiar notions of spontaneous symmetry breaking and topological order. I will point out that in the many body localized regime, spontaneous symmetry breaking can occur even at high energy densities in one dimensional systems, and topological order can occur even without a bulk gap. I will also discuss the phenomenology of imperfectly isolated many body localized systems, which are weakly coupled to a heat bath. I will conclude with a brief discussion of how these phenomena may best be detected in experiments. Collaborators: David Huse, S.L. Sondhi, Arijeet Pal, Vadim Oganesyan, A.C. Potter, Sarang Gopalakrishnan, S. Johri, R.N. Bhatt.

  18. Fractional order junctions

    NASA Astrophysics Data System (ADS)

    Machado, J. Tenreiro

    2015-01-01

    Gottfried Leibniz generalized the derivation and integration, extending the operators from integer up to real, or even complex, orders. It is presently recognized that the resulting models capture long term memory effects difficult to describe by classical tools. Leon Chua generalized the set of lumped electrical elements that provide the building blocks in mathematical models. His proposal of the memristor and of higher order elements broadened the scope of variables and relationships embedded in the development of models. This paper follows the two directions and proposes a new logical step, by generalizing the concept of junction. Classical junctions interconnect system elements using simple algebraic restrictions. Nevertheless, this simplistic approach may be misleading in the presence of unexpected dynamical phenomena and requires including additional "parasitic" elements. The novel γ -junction includes, as special cases, the standard series and parallel connections and allows a new degree of freedom when building models. The proposal motivates the search for experimental and real world manifestations of the abstract conjectures.

  19. Computerized Physician Order Entry

    PubMed Central

    Khanna, Raman; Yen, Tony

    2014-01-01

    Computerized physician order entry (CPOE) has been promoted as an important component of patient safety, quality improvement, and modernization of medical practice. In practice, however, CPOE affects health care delivery in complex ways, with benefits as well as risks. Every implementation of CPOE is associated with both generally recognized and unique local factors that can facilitate or confound its rollout, and neurohospitalists will often be at the forefront of such rollouts. In this article, we review the literature on CPOE, beginning with definitions and proceeding to comparisons to the standard of care. We then proceed to discuss clinical decision support systems, negative aspects of CPOE, and cultural context of CPOE implementation. Before concluding, we follow the experiences of a Chief Medical Information Officer and neurohospitalist who rolled out a CPOE system at his own health care organization and managed the resulting workflow changes and setbacks. PMID:24381708

  20. Birth order and myopia

    PubMed Central

    Guggenheim, Jeremy A.; McMahon, George; Northstone, Kate; Mandel, Yossi; Kaiserman, Igor; Stone, Richard A.; Lin, Xiaoyu; Saw, Seang Mei; Forward, Hannah; Mackey, David A.; Yazar, Seyhan; Young, Terri L.; Williams, Cathy

    2013-01-01

    Purpose An association between birth order and reduced unaided vision (a surrogate for myopia) has been observed previously. We examined the association between birth order and myopia directly in 4 subject groups. Methods Subject groups were participants in 1) the Avon Longitudinal Study of Parents and Children (ALSPAC; UK; age 15 years; N=4,401), 2) the Singapore Cohort Study of Risk Factors for Myopia (SCORM; Singapore; age 13 years; N=1,959), 3) the Raine Eye Health Study (REHS; Australia; age 20 years; N=1,344), and 4) Israeli Defense Force recruitment candidates (IDFC; Israel; age 16-22 years; N=888,277). Main outcome: Odds ratio (OR) for myopia in first born versus non-first born individuals after adjusting for potential risk factors. Results The prevalence of myopia was numerically higher in first-born versus non-first-born individuals in all study groups, but the strength of evidence varied widely. The adjusted ORs (95% CI) were: ALSPAC, 1.31 (1.05-1.64); SCORM, 1.25 (0.89-1.77); REHS, 1.18 (0.90-1.55); IDFC, 1.04 (1.03-1.06). In the large IDFC sample, the effect size was greater (a) for the first born versus fourth or higher born comparison than for the first born versus second/third born comparison (P<0.001) and (b) with increasing myopia severity (P<0.001). Conclusions Across all studies, the increased risk of myopia in first born individuals was low (OR <1.3). Indeed, only the studies with >4000 participants provided strong statistical support for the association. The available evidence suggested the relationship was independent of established risk factors such as time outdoors/reading, and thus may arise through a different causal mechanism. PMID:24168726

  1. Order without design.

    PubMed

    Kurakin, Alexei

    2010-01-01

    Experimental reality in molecular and cell biology, as revealed by advanced research technologies and methods, is manifestly inconsistent with the design perspective on the cell, thus creating an apparent paradox: where do order and reproducibility in living systems come from if not from design? I suggest that the very idea of biological design (whether evolutionary or intelligent) is a misconception rooted in the time-honored and thus understandably precious error of interpreting living systems/organizations in terms of classical mechanics and equilibrium thermodynamics. This error, introduced by the founders and perpetuated due to institutionalization of science, is responsible for the majority of inconsistencies, contradictions, and absurdities plaguing modern sciences, including one of the most startling paradoxes - although almost everyone agrees that any living organization is an open nonequilibrium system of continuous energy/matter flow, almost everyone interprets and models living systems/organizations in terms of classical mechanics, equilibrium thermodynamics, and engineering, i.e., in terms and concepts that are fundamentally incompatible with the physics of life. The reinterpretation of biomolecules, cells, organisms, ecosystems, and societies in terms of open nonequilibrium organizations of energy/matter flow suggests that, in the domain of life, order and reproducibility do not come from design. Instead, they are natural and inevitable outcomes of self-organizing activities of evolutionary successful, and thus persistent, organizations co-evolving on multiple spatiotemporal scales as biomolecules, cells, organisms, ecosystems, and societies. The process of self-organization on all scales is driven by economic competition, obeys empirical laws of nonequilibrium thermodynamics, and is facilitated and, thus, accelerated by memories of living experience persisting in the form of evolutionary successful living organizations and their constituents. PMID

  2. Order without design

    PubMed Central

    2010-01-01

    Experimental reality in molecular and cell biology, as revealed by advanced research technologies and methods, is manifestly inconsistent with the design perspective on the cell, thus creating an apparent paradox: where do order and reproducibility in living systems come from if not from design? I suggest that the very idea of biological design (whether evolutionary or intelligent) is a misconception rooted in the time-honored and thus understandably precious error of interpreting living systems/organizations in terms of classical mechanics and equilibrium thermodynamics. This error, introduced by the founders and perpetuated due to institutionalization of science, is responsible for the majority of inconsistencies, contradictions, and absurdities plaguing modern sciences, including one of the most startling paradoxes - although almost everyone agrees that any living organization is an open nonequilibrium system of continuous energy/matter flow, almost everyone interprets and models living systems/organizations in terms of classical mechanics, equilibrium thermodynamics, and engineering, i.e., in terms and concepts that are fundamentally incompatible with the physics of life. The reinterpretation of biomolecules, cells, organisms, ecosystems, and societies in terms of open nonequilibrium organizations of energy/matter flow suggests that, in the domain of life, order and reproducibility do not come from design. Instead, they are natural and inevitable outcomes of self-organizing activities of evolutionary successful, and thus persistent, organizations co-evolving on multiple spatiotemporal scales as biomolecules, cells, organisms, ecosystems, and societies. The process of self-organization on all scales is driven by economic competition, obeys empirical laws of nonequilibrium thermodynamics, and is facilitated and, thus, accelerated by memories of living experience persisting in the form of evolutionary successful living organizations and their constituents. PMID

  3. 40 CFR 305.27 - Accelerated order, order to dismiss.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 28 2014-07-01 2014-07-01 false Accelerated order, order to dismiss... Prehearing Procedures § 305.27 Accelerated order, order to dismiss. (a) General. The Presiding Officer, upon motion of any party or sua sponte, may at any time render an accelerated order in favor of the...

  4. 48 CFR 53.216-1 - Delivery orders and orders under basic ordering agreements (OF 347).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... under basic ordering agreements (OF 347). 53.216-1 Section 53.216-1 Federal Acquisition Regulations... Delivery orders and orders under basic ordering agreements (OF 347). OF 347, Order for Supplies or Services. OF 347, prescribed in 53.213(f), (or an approved agency form) may be used to place orders...

  5. Simulations of molecular dynamics in solid-state NMR spectra of spin-1 nuclei including effects of CSA- and EFG-terms up to second order.

    PubMed

    Larsen, Flemming H

    2007-04-01

    By numerical simulations MAS and QCPMG methods for acquiring spectra of spin-1 nuclei were compared in order to determine the most sensitive experiment for analysis of molecular dynamics. To comply with the large quadrupolar constants for 14N and the CSA reported for 6Li both of these interactions are included up to second order. For 2H and 6Li both QCPMG and single-pulse MAS experiments were suitable for dynamics studies whereas the single-pulse MAS experiment were the method of choice for investigation of 14N dynamics for C(Q)'s larger than 750kHz at 14.1T. This property prohibits excitation of the 14N lineshape using either single hard or softer composite rf-pulses. Focusing on 14N it was demonstrated that the centerband lineshape is sensitive toward both off-MAS and CSA effects. In addition, excitation by real-time pulses showed that proper lineshapes corresponding to a site with a C(Q) of 3MHz may be excited by a very short pulse. PMID:17418539

  6. Oligorotaxane Radicals under Orders.

    PubMed

    Wang, Yuping; Frasconi, Marco; Liu, Wei-Guang; Sun, Junling; Wu, Yilei; Nassar, Majed S; Botros, Youssry Y; Goddard, William A; Wasielewski, Michael R; Stoddart, J Fraser

    2016-02-24

    A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components-namely oligoviologens-in which different numbers of 4,4'-bipyridinium (BIPY(2+)) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT(4+)) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY(•+) radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne-azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers. PMID:27163033

  7. Oligorotaxane Radicals under Orders

    PubMed Central

    2016-01-01

    A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components—namely oligoviologens—in which different numbers of 4,4′-bipyridinium (BIPY2+) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT4+) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY•+ radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne–azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers. PMID:27163033

  8. 14 CFR 13.20 - Orders of compliance, cease and desist orders, orders of denial, and other orders.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Orders of compliance, cease and desist orders, orders of denial, and other orders. 13.20 Section 13.20 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PROCEDURAL RULES INVESTIGATIVE AND ENFORCEMENT PROCEDURES Legal Enforcement Actions § 13.20 Orders...

  9. Isotropic sequence order learning.

    PubMed

    Porr, Bernd; Wörgötter, Florentin

    2003-04-01

    In this article, we present an isotropic unsupervised algorithm for temporal sequence learning. No special reward signal is used such that all inputs are completely isotropic. All input signals are bandpass filtered before converging onto a linear output neuron. All synaptic weights change according to the correlation of bandpass-filtered inputs with the derivative of the output. We investigate the algorithm in an open- and a closed-loop condition, the latter being defined by embedding the learning system into a behavioral feedback loop. In the open-loop condition, we find that the linear structure of the algorithm allows analytically calculating the shape of the weight change, which is strictly heterosynaptic and follows the shape of the weight change curves found in spike-time-dependent plasticity. Furthermore, we show that synaptic weights stabilize automatically when no more temporal differences exist between the inputs without additional normalizing measures. In the second part of this study, the algorithm is is placed in an environment that leads to closed sensor-motor loop. To this end, a robot is programmed with a prewired retraction reflex reaction in response to collisions. Through isotropic sequence order (ISO) learning, the robot achieves collision avoidance by learning the correlation between his early range-finder signals and the later occurring collision signal. Synaptic weights stabilize at the end of learning as theoretically predicted. Finally, we discuss the relation of ISO learning with other drive reinforcement models and with the commonly used temporal difference learning algorithm. This study is followed up by a mathematical analysis of the closed-loop situation in the companion article in this issue, "ISO Learning Approximates a Solution to the Inverse-Controller Problem in an Unsupervised Behavioral Paradigm" (pp. 865-884). PMID:12689389

  10. Do-not-resuscitate order

    MedlinePlus

    ... order; DNR; DNR order; Advance care directive - DNR; Health care agent - DNR; Health care proxy - DNR; End-of-life - DNR; Living ... medical order written by a doctor. It instructs health care providers not to do cardiopulmonary resuscitation (CPR) ...

  11. 49 CFR 453.3 - Detention orders and other orders.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Detention orders and other orders. 453.3 Section 453.3 Transportation Other Regulations Relating to Transportation (Continued) COAST GUARD, DEPARTMENT OF HOMELAND SECURITY SAFETY APPROVAL OF CARGO CONTAINERS CONTROL AND ENFORCEMENT § 453.3 Detention orders and other orders. (a) The terms of...

  12. 49 CFR 453.3 - Detention orders and other orders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 6 2011-10-01 2011-10-01 false Detention orders and other orders. 453.3 Section 453.3 Transportation Other Regulations Relating to Transportation (Continued) COAST GUARD, DEPARTMENT OF HOMELAND SECURITY SAFETY APPROVAL OF CARGO CONTAINERS CONTROL AND ENFORCEMENT § 453.3 Detention orders and other orders. (a) The terms of...

  13. 48 CFR 53.216-1 - Delivery orders and orders under basic ordering agreements (OF 347).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 2 2014-10-01 2014-10-01 false Delivery orders and orders under basic ordering agreements (OF 347). 53.216-1 Section 53.216-1 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION (CONTINUED) CLAUSES AND FORMS FORMS Prescription of Forms 53.216-1 Delivery orders and orders under...

  14. Topology in Ordered Phases

    NASA Astrophysics Data System (ADS)

    Tanda, Satoshi; Matsuyama, Toyoki; Oda, Migaku; Asano, Yasuhiro; Yakubo, Kousuke

    2006-08-01

    .]. Nanofibers of hydrogen storage alloy / I. Saita ... [et al.]. Synthesis of stable icosahedral quasicrystals in Zn-Sc based alloys and their magnetic properties / S. Kashimoto and T. Ishimasa. One-armed spiral wave excited by eam pressure in accretion disks in Be/X-Ray binaries / K. Hayasaki and A. T. Okazaki -- IV. Topological defects and excitations. Topological excitations in the ground state of charge density wave systems / P. Monceau. Soliton transport in nanoscale charge-density-wave systems / K. Inagaki, T. Toshima and S. Tanda. Topological defects in triplet superconductors UPt3, Sr[symbol]RuO[symbol], etc. / K. Maki ... [et al.]. Microscopic structure of vortices in type II superconductors / K. Machida ... [et al.]. Microscopic neutron investigation of the Abrikosov state of high-temperature superconductors / J. Mesot. Energy dissipation at nano-scale topological defects of high-Tc superconductors: microwave study / A. Maeda. Pressure induced topological phase transition in the heavy Fermion compound CeAl[symbol] / H. Miyagawa ... [et al.]. Explanation for the unusual orientation of LSCO square vortex lattice in terms of nodal superconductivity / M. Oda. Local electronic states in Bi[symbol]Sr[symbol]CaCu[symbol]O[symbol] / A. Hashimoto ... [et al.] -- V. Topology in quantum phenomena. Topological vortex formation in a Bose-Einstein condensate of alkali-metal atoms / M. Nakahara. Quantum phase transition of [symbol]He confined in nano-porous media / K. Shirahama, K. Yamamoto and Y. Shibayama. A new mean-field theory for Bose-Einstein condensates / T. Kita. Spin current in topological cristals / Y. Asano. Antiferromagnetic defects in non-magnetic hidden order of the heavy-electron system URu[symbol]Si[symbol] / H. Amitsuka, K. Tenya and M. Yokoyama. Magnetic-field dependences of thermodynamic quantities in the vortex state of Type-II superconductors / K. Watanabe, T. Kita and M. Arai. Three-magnon-mediated nuclear spin relaxation in quantum ferrimagnets of topological

  15. Order sets utilization in a clinical order entry system.

    PubMed

    Cowden, Daniel; Barbacioru, Catalin; Kahwash, Eiad; Saltz, Joel

    2003-01-01

    An order set is a predefined template that has been utilized in the standard care of hospitals for many years. While in the past, it took the form of pen and paper, today, it is, indeed, electronic. Within order sets are distinct ordering patterns that may yield fruitful results for clinicians and informaticians, alike. Protocols like there electronic counterpart, order sets, provide an 'indication' identifying the clinical scenario of the patient's condition when the ordering event occurred. This 'indication' is rarely captured by individual orders, and provides difficult challenges to developers of information systems. While mandating an 'indication' be entered for every medication or lab order makes the job much more tasking on the physician provider, it is appealing to researchers and accountants. We have attempted to bypasses that consideration by identifying ordering patterns that predict diagnostic related codes (DRGs) and diagnostic codes which would greatly facilitate the information gathering process and still provide a flexible and user friendly physician interface. PMID:14728324

  16. Protective orders: questions and conundrums.

    PubMed

    Logan, T K; Shannon, Lisa; Walker, Robert; Faragher, Teri Marie

    2006-07-01

    Current media portrayal of protective orders is often negative, focusing on weaknesses in how protective orders are obtained and enforced. This review of research findings on protective orders examines issues and suggests areas in need of future research to clarify and improve public policy. More specifically, this review has five main objectives: (a) to provide background information about partner violence and the need for protective orders; (b) to describe what protective orders are, how many women obtain them, and the advantages and disadvantages of obtaining protective orders; (c) to examine characteristics of women who seek protective orders; (d) to explore research on whether protective orders actually increase women's safety; and (e) to highlight opportunities and gaps in the practice and research literature regarding the use of protective orders for women with violent partners or ex-partners. PMID:16785286

  17. Water dynamics on ice and hydrate lattices studied by second-order central-line stimulated-echo oxygen-17 nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Adjei-Acheamfour, Mischa; Tilly, Julius F.; Beerwerth, Joachim; Böhmer, Roland

    2015-12-01

    Oxygen-17 stimulated-echo spectroscopy is a novel nuclear magnetic resonance (NMR) technique that allows one to investigate the time scale and geometry of ultraslow molecular motions in materials containing oxygen. The method is based on detecting orientationally encoded frequency changes within oxygen's central-transition NMR line that are caused by second-order quadrupolar interactions. In addition to the latter, the present theoretical analysis of various two-pulse echo and stimulated-echo pulse sequences takes also heteronuclear dipolar interactions into account. As an experimental example, the ultraslow water motion in polycrystals of tetrahydrofuran clathrate hydrate is studied via two-time oxygen-17 stimulated-echo correlation functions. The resulting correlation times and those of hexagonal ice are similar to those from previous deuteron NMR measurements. Calculations of the echo functions' final-state correlations for various motional models are compared with the experimental data of the clathrate hydrate. It is found that a six-site model including the oxygen-proton dipolar interaction describes the present results.

  18. Water dynamics on ice and hydrate lattices studied by second-order central-line stimulated-echo oxygen-17 nuclear magnetic resonance

    SciTech Connect

    Adjei-Acheamfour, Mischa; Tilly, Julius F.; Beerwerth, Joachim; Böhmer, Roland

    2015-12-07

    Oxygen-17 stimulated-echo spectroscopy is a novel nuclear magnetic resonance (NMR) technique that allows one to investigate the time scale and geometry of ultraslow molecular motions in materials containing oxygen. The method is based on detecting orientationally encoded frequency changes within oxygen’s central-transition NMR line that are caused by second-order quadrupolar interactions. In addition to the latter, the present theoretical analysis of various two-pulse echo and stimulated-echo pulse sequences takes also heteronuclear dipolar interactions into account. As an experimental example, the ultraslow water motion in polycrystals of tetrahydrofuran clathrate hydrate is studied via two-time oxygen-17 stimulated-echo correlation functions. The resulting correlation times and those of hexagonal ice are similar to those from previous deuteron NMR measurements. Calculations of the echo functions’ final-state correlations for various motional models are compared with the experimental data of the clathrate hydrate. It is found that a six-site model including the oxygen-proton dipolar interaction describes the present results.

  19. Quadrupole sensitive pulse for signal filtering

    NASA Astrophysics Data System (ADS)

    Evgeny, Nimerovsky; Jerschow, Alexej

    2016-04-01

    A longstanding problem in quadrupolar NMR of semi-solids is the selection of signals originating from ordered nuclei, i.e. those that experience a non-vanishing quadrupolar coupling. Established techniques, such as for example multiple-quantum filters are not adequate in situations when the radio frequency power is on the order of the quadrupolar coupling or the quadrupolar relaxation rates, such as may be the case on an MRI scanner, or in ex situ applications. In this manuscript we show a new method for the selective excitation of ordered spin-3/2 nuclei, which produces the desired results when the radio frequency power is approximately equal or smaller than quadrupolar frequency. Using a combination of simulations and experiments with 23Na in NaCl solution, Pf1-solutions, and bovine patellar cartilage samples we further show how the value of the quadrupolar frequency and global features of a quadrupolar coupling distribution can be extracted from these experiments.

  20. Olson Order of Quantum Observables

    NASA Astrophysics Data System (ADS)

    Dvurečenskij, Anatolij

    2016-07-01

    M.P. Olson, Proc. Am. Math. Soc. 28, 537-544 (1971) showed that the system of effect operators of the Hilbert space can be ordered by the so-called spectral order such that the system of effect operators is a complete lattice. Using his ideas, we introduce a partial order, called the Olson order, on the set of bounded observables of a complete lattice effect algebra. We show that the set of bounded observables is a Dedekind complete lattice.

  1. Structural order in glassy water.

    PubMed

    Giovambattista, Nicolas; Debenedetti, Pablo G; Sciortino, Francesco; Stanley, H Eugene

    2005-06-01

    We investigate structural order in glassy water by performing classical molecular dynamics simulations using the extended simple point charge (SPC/E) model of water. We perform isochoric cooling simulations across the glass transition temperature at different cooling rates and densities. We quantify structural order by orientational and translational order metrics. Upon cooling the liquid into the glassy state, both the orientational order parameter Q and translational order parameter tau increase. At T=0 K, the glasses fall on a line in the Q-tau plane or order map. The position of this line depends only on density and coincides with the location in the order map of the inherent structures (IS) sampled upon cooling. We evaluate the energy of the IS, eIS(T), and find that both order parameters for the IS are proportional to eIS. We also study the structural order during the transformation of low-density amorphous ice (LDA) to high-density amorphous ice (HDA) upon isothermal compression and are able to identify distinct regions in the order map corresponding to these glasses. Comparison of the order parameters for LDA and HDA with those obtained upon isochoric cooling indicates major structural differences between glasses obtained by cooling and glasses obtained by compression. These structural differences are only weakly reflected in the pair correlation function. We also characterize the evolution of structural order upon isobaric annealing, leading at high pressure to very-high density amorphous ice (VHDA). PMID:16089741

  2. Ordered delinquency: the "effects" of birth order on delinquency.

    PubMed

    Cundiff, Patrick R

    2013-08-01

    Juvenile delinquency has long been associated with birth order in popular culture. While images of the middle child acting out for attention or the rebellious youngest child readily spring to mind, little research has attempted to explain why. Drawing from Adlerian birth order theory and Sulloway's born-to-rebel hypothesis, I examine the relationship between birth order and a variety of delinquent outcomes during adolescence. Following some recent research on birth order and intelligence, I use new methods that allow for the examination of between-individual and within-family differences to better address the potential spurious relationship. My findings suggest that contrary to popular belief, the relationship between birth order and delinquency is spurious. Specifically, I find that birth order effects on delinquency are spurious and largely products of the analytic methods used in previous tests of the relationship. The implications of this finding are discussed. PMID:23719623

  3. 7 CFR 1216.16 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.16 Order. Order...

  4. 7 CFR 1216.16 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.16 Order. Order...

  5. 7 CFR 1216.16 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.16 Order. Order...

  6. 7 CFR 1216.16 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.16 Order. Order...

  7. 7 CFR 1216.16 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.16 Order. Order...

  8. 7 CFR 1221.18 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.18 Order. Order...

  9. 7 CFR 1221.18 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.18 Order. Order...

  10. 7 CFR 1221.18 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.18 Order. Order...

  11. 7 CFR 1221.18 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.18 Order. Order...

  12. 7 CFR 1221.18 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE SORGHUM PROMOTION, RESEARCH, AND INFORMATION ORDER Sorghum Promotion, Research, and Information Order Definitions § 1221.18 Order. Order...

  13. 40 CFR 305.27 - Accelerated order, order to dismiss.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 27 2010-07-01 2010-07-01 false Accelerated order, order to dismiss. 305.27 Section 305.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SUPERFUND, EMERGENCY PLANNING, AND COMMUNITY RIGHT-TO-KNOW PROGRAMS COMPREHENSIVE ENVIRONMENTAL RESPONSE,...

  14. Counterbalancing for Serial Order Carryover Effects in Experimental Condition Orders

    ERIC Educational Resources Information Center

    Brooks, Joseph L.

    2012-01-01

    Reactions of neural, psychological, and social systems are rarely, if ever, independent of previous inputs and states. The potential for serial order carryover effects from one condition to the next in a sequence of experimental trials makes counterbalancing of condition order an essential part of experimental design. Here, a method is proposed…

  15. Ordering within Moral Orders to Manage Classroom Trouble

    ERIC Educational Resources Information Center

    Doherty, Catherine; McGregor, Rowena; Shield, Paul

    2016-01-01

    This paper demonstrates how classroom trouble warranting teacher intervention can stem from transgressions in different layers of the complex moral order regulating classroom interactions. The paper builds from Durkheim's treatment of schooling as the institution responsible for the inculcation of a shared moral order, Bernstein's distinction…

  16. Surface melting of electronic order.

    SciTech Connect

    Wilkins, S. B.; Liu, X.; Wakabayashi, Y.; Kim, J.-W.; Ryan, P. J.; Mitchell, J. F.; Hill, J. P.

    2011-01-01

    We report temperature-dependent surface x-ray scattering studies of the orbital ordered surface in La{sub 0.5}Sr{sub 1.5}MnO{sub 4}. We find that as the bulk ordering temperature is approached from below the thickness of the interface between the electronically ordered and electronically disordered regions at the surface grows, though the bulk correlation length remains unchanged. Close to the transition, the surface is so rough that there is no well-defined electronic surface, despite the presence of bulk electronic order. That is, the electronic ordering at the surface has melted. Above the bulk transition, long-range ordering in the bulk is destroyed but finite-sized isotropic fluctuations persist, with a correlation length roughly equal to that of the low-temperature in-plane surface correlation length.

  17. Order stars and stiff integrators

    NASA Astrophysics Data System (ADS)

    Hairer, Ernst; Wanner, Gerhard

    2000-12-01

    Order stars, introduced in G. Wanner, E. Hairer, S.P. Nørsett (Order stars and stability theorems, BIT 18 (1978) 475-489), have become a fundamental tool for the understanding of order and stability properties of numerical methods for stiff differential equations. This survey retraces their discovery and their principal achievements. We also sketch some later extensions and describe some recent developments.

  18. Symmetry of Magnetically Ordered Quasicrystals

    NASA Astrophysics Data System (ADS)

    Lifshitz, Ron

    1998-03-01

    The notion of magnetic symmetry is reexamined in light of the recent observation of long-range magnetic order in icosahedral quasicrystals [Charrier et al., Phys. Rev. Lett. 78, 4637 (1997)]. The relation between the symmetry of a magnetically ordered (periodic or quasiperiodic) crystal, given in terms of a ``spin space group,'' and its neutron diffraction diagram is established. In doing so, an outline of a symmetry classification scheme for magnetically ordered quasiperiodic crystals, is provided. Predictions are given for the expected diffraction patterns of magnetically ordered icosahedral crystals, provided their symmetry is well described by icosahedral spin space groups.

  19. Orientational order in disordered superconductors

    SciTech Connect

    Toner, J. )

    1991-05-13

    Orientational order in weakly pinned Abrikosov flux lattices is studied, taking into account two heretofore neglected effects: dislocations and orientational couplings to the underlying lattice. Without orientational couplings, arbitrarily weak pinning destroys long-ranged orientational order for all spatial dimensions {ital d}{lt}4. Orientational couplings stabilize long-ranged orientational order. For fields along an axis of {ital fourfold} symmetry, {ital sixfold} (hexatic) orientational order is described by a random-field Ising model, and so does not occur in {ital d}=2 (thin films) but does in {ital d}=3 (bulk).

  20. Equilibrium structures of anisometric, quadrupolar particles confined to a monolayer.

    PubMed

    Heinemann, Thomas; Antlanger, Moritz; Mazars, Martial; Klapp, Sabine H L; Kahl, Gerhard

    2016-02-21

    We investigate the structural properties of a two-dimensional system of ellipsoidal particles carrying a linear quadrupole moment in their center. These particles represent a simple model for a variety of uncharged, non-polar conjugated organic molecules. Using optimization tools based on ideas of evolutionary algorithms, we first examine the ground state structures as we vary the aspect ratio of the particles and the pressure. Interestingly, we find, besides the intuitively expected T-like configurations, a variety of complex structures, characterized with up to three different particle orientations. In an effort to explore the impact of thermal fluctuations, we perform constant-pressure molecular dynamics simulations within a range of rather low temperatures. We observe that ground state structures formed by particles with a large aspect ratio are in particular suited to withstand fluctuations up to rather high temperatures. Our comprehensive investigations allow for a deeper understanding of molecular or colloidal monolayer arrangements under the influence of a typical electrostatic interaction on a coarse-grained level. PMID:26896992

  1. Equilibrium structures of anisometric, quadrupolar particles confined to a monolayer

    NASA Astrophysics Data System (ADS)

    Heinemann, Thomas; Antlanger, Moritz; Mazars, Martial; Klapp, Sabine H. L.; Kahl, Gerhard

    2016-02-01

    We investigate the structural properties of a two-dimensional system of ellipsoidal particles carrying a linear quadrupole moment in their center. These particles represent a simple model for a variety of uncharged, non-polar conjugated organic molecules. Using optimization tools based on ideas of evolutionary algorithms, we first examine the ground state structures as we vary the aspect ratio of the particles and the pressure. Interestingly, we find, besides the intuitively expected T-like configurations, a variety of complex structures, characterized with up to three different particle orientations. In an effort to explore the impact of thermal fluctuations, we perform constant-pressure molecular dynamics simulations within a range of rather low temperatures. We observe that ground state structures formed by particles with a large aspect ratio are in particular suited to withstand fluctuations up to rather high temperatures. Our comprehensive investigations allow for a deeper understanding of molecular or colloidal monolayer arrangements under the influence of a typical electrostatic interaction on a coarse-grained level.

  2. A quadrupolar complete model of the hot disc

    NASA Astrophysics Data System (ADS)

    Jannot, Yves; Acem, Zoubir

    2007-05-01

    The hot disc method is a transient plane source method used for the estimation of the thermal conductivity and diffusivity of solid materials. A complete model based on the thermal quadrupoles formalism has been developed to represent the hot disc temperature variation. This model takes into account both the thermal contact resistance between the solid to be characterized and the hot disc and the thermal inertia of the hot disc. It makes it possible to realize the parameters estimation on all the recorded temperature measurements. This model is used to highlight the estimation uncertainty due to approximations in the heat transfer model.

  3. Constructing higher-order hydrodynamics: The third order

    NASA Astrophysics Data System (ADS)

    Grozdanov, Sašo; Kaplis, Nikolaos

    2016-03-01

    Hydrodynamics can be formulated as the gradient expansion of conserved currents in terms of the fundamental fields describing the near-equilibrium fluid flow. In the relativistic case, the Navier-Stokes equations follow from the conservation of the stress-energy tensor to first order in derivatives. In this paper, we go beyond the presently understood second-order hydrodynamics and discuss the systematization of obtaining the hydrodynamic expansion to an arbitrarily high order. As an example of the algorithm that we present, we fully classify the gradient expansion at third order for neutral fluids in four dimensions, thus finding the most general next-to-leading-order corrections to the relativistic Navier-Stokes equations in curved space-time. In doing so, we list 20 new transport coefficient candidates in the conformal case and 68 in the nonconformal case. As we do not consider any constraints that could potentially arise from the local entropy current analysis, this is the maximal possible set of neutral third-order transport coefficients. To investigate the physical implications of these new transport coefficients, we obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We also compute the corrections to the scalar (spin-2) two-point correlation function of the third-order stress-energy tensor. Furthermore, as an example of a nonlinear hydrodynamic flow, we calculate the third-order corrections to the energy density of a boost-invariant Bjorken flow. Finally, we apply our field theoretic results to the N =4 supersymmetric Yang-Mills fluid at infinite 't Hooft coupling and an infinite number of colors to find the values of five new linear combinations of the conformal transport coefficients.

  4. High-Order/Low-Order methods for ocean modeling

    SciTech Connect

    Newman, Christopher; Womeldorff, Geoff; Chacón, Luis; Knoll, Dana A.

    2015-06-01

    We examine a High Order/Low Order (HOLO) approach for a z-level ocean model and show that the traditional semi-implicit and split-explicit methods, as well as a recent preconditioning strategy, can easily be cast in the framework of HOLO methods. The HOLO formulation admits an implicit-explicit method that is algorithmically scalable and second-order accurate, allowing timesteps much larger than the barotropic time scale. We demonstrate how HOLO approaches, in particular the implicit-explicit method, can provide a solid route for ocean simulation to heterogeneous computing and exascale environments.

  5. Birth Order: Reconciling Conflicting Effects.

    ERIC Educational Resources Information Center

    Zajonc, Robert B.; Mullally, Patricia R.

    1997-01-01

    Introduces the confluence model as a theory specifying the process by which the intellectual environment modifies intellectual development. Using this model, explores the contradiction between prediction of secular trends in test scores by trends in aggregate birth order and the lack of prediction of individual test scores by birth order using…

  6. Problem Order Implications for Learning

    ERIC Educational Resources Information Center

    Li, Nan; Cohen, William W.; Koedinger, Kenneth R.

    2013-01-01

    The order of problems presented to students is an important variable that affects learning effectiveness. Previous studies have shown that solving problems in a blocked order, in which all problems of one type are completed before the student is switched to the next problem type, results in less effective performance than does solving the problems…

  7. Orderings for conjugate gradient preconditionings

    NASA Technical Reports Server (NTRS)

    Ortega, James M.

    1991-01-01

    The effect of orderings on the rate of convergence of the conjugate gradient method with SSOR or incomplete Cholesky preconditioning is examined. Some results also are presented that help to explain why red/black ordering gives an inferior rate of convergence.

  8. Tensions between Liberty and Order.

    ERIC Educational Resources Information Center

    Chemerinsky, Erwin

    2002-01-01

    Explores the issue of balancing liberty and order within the United States. Discusses the role of the Bill of Rights, focusing on the amendments in the document and the later amendments that ensure the liberty of U.S. citizens. Explains how order and liberty are ensured and includes discussion questions. (CMK)

  9. Light nuclei with improved order-by-order chiral interactions

    NASA Astrophysics Data System (ADS)

    Maris, Pieter; Vary, James

    2015-10-01

    We present recent results for light nuclei obtained with improved NN interactions derived from chiral effective field theory up to N4LO. The many-body calculations are performed order-by-order in the chiral expansion. We show results for the ground state energies and the low-lying spectrum; in addition we discuss other observables such as magnetic and quadrupole moments. We discuss both the theoretical uncertainties due to the truncation of the chiral expansion, as well as the numerical uncertainties associated with the many-body method. Depending on the value chiral order, additional renormalization using the Similarity Renormalization Group is needed in order to improve numerical convergence of the many-body calculations. Supported by the US DOE grants DESC0008485 (SciDAC/NUCLEI) and DE-FG02-87ER40371. Computational resources provided by NERSC (supported by US DOE contract DE-AC02-05CH11231).

  10. Engineering charge ordering into multiferroicity

    NASA Astrophysics Data System (ADS)

    He, Xu; Jin, Kui-juan

    2016-04-01

    Multiferroic materials have attracted great interest but are rare in nature. In many transition-metal oxides, charge ordering and magnetic ordering coexist, so that a method of engineering charge-ordered materials into ferroelectric materials would lead to a large class of multiferroic materials. We propose a strategy for designing new ferroelectric or even multiferroic materials by inserting a spacing layer into each two layers of charge-ordered materials and artificially making a superlattice. One example of the model demonstrated here is the perovskite (LaFeO3)2/LaTiO3 (111) superlattice, in which the LaTiO3 layer acts as the donor and the spacing layer, and the LaFeO3 layer is half doped and performs charge ordering. The collaboration of the charge ordering and the spacing layer breaks the space inversion symmetry, resulting in a large ferroelectric polarization. As the charge ordering also leads to a ferrimagnetic structure, (LaFeO3)2/LaTiO3 is multiferroic. It is expected that this work can encourage the designing and experimental implementation of a large class of multiferroic structures with novel properties.

  11. Court-ordered obstetrical interventions.

    PubMed

    Kolder, V E; Gallagher, J; Parsons, M T

    1987-05-01

    In a national survey, we investigated the scope and circumstances of court-ordered obstetrical procedures in cases in which the women had refused therapy deemed necessary for the fetus. We also solicited the opinions of leading obstetricians regarding such cases. Court orders have been obtained for cesarean sections in 11 states, for hospital detentions in 2 states, and for intrauterine transfusions in 1 state. Among 21 cases in which court orders were sought, the orders were obtained in 86 percent; in 88 percent of those cases, the orders were received within six hours. Eighty-one percent of the women involved were black, Asian, or Hispanic, 44 percent were unmarried, and 24 percent did not speak English as their primary language. All the women were treated in a teaching-hospital clinic or were receiving public assistance. No important maternal morbidity or mortality was reported. Forty-six percent of the heads of fellowship programs in maternal-fetal medicine thought that women who refused medical advice and thereby endangered the life of the fetus should be detained. Forty-seven percent supported court orders for procedures such as intrauterine transfusions. We conclude from these data that court-ordered obstetrical procedures represent an important and growing problem that evokes sharply divided responses from faculty members in obstetrics. Such procedures are based on dubious legal grounds, and they may have far-reaching implications for obstetrical practice and maternal and infant health. PMID:3574370

  12. 7 CFR 1208.14 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PROCESSED RASPBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Processed Raspberry Promotion, Research, and Information Order Definitions § 1208.14 Order. Order means the Processed Raspberry Promotion, Research, and Information Order....

  13. 7 CFR 1208.14 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PROCESSED RASPBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Processed Raspberry Promotion, Research, and Information Order Definitions § 1208.14 Order. Order means the Processed Raspberry Promotion, Research, and Information Order....

  14. Multiple order common path spectrometer

    NASA Technical Reports Server (NTRS)

    Newbury, Amy B. (Inventor)

    2010-01-01

    The present invention relates to a dispersive spectrometer. The spectrometer allows detection of multiple orders of light on a single focal plane array by splitting the orders spatially using a dichroic assembly. A conventional dispersion mechanism such as a defraction grating disperses the light spectrally. As a result, multiple wavelength orders can be imaged on a single focal plane array of limited spectral extent, doubling (or more) the number of spectral channels as compared to a conventional spectrometer. In addition, this is achieved in a common path device.

  15. 7 CFR 1218.12 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....

  16. 7 CFR 1218.12 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....

  17. 7 CFR 1218.12 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....

  18. 7 CFR 1218.12 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....

  19. 7 CFR 1218.12 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....

  20. 7 CFR 1206.13 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...

  1. 7 CFR 1206.13 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...

  2. 7 CFR 1206.13 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...

  3. 7 CFR 1206.13 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...

  4. 7 CFR 1206.13 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...

  5. Order, Chaos and All That!

    ERIC Educational Resources Information Center

    Glasser, L.

    1989-01-01

    The evolution of ideas about the concept of chaos is surveyed. Discussed are chaos in deterministic, dynamic systems; order in dissipative systems; and thermodynamics and irreversibility. Included are logistic and bifurcation maps to illustrate points made in the discussion. (CW)

  6. Birth Order and Vocational Interest

    ERIC Educational Resources Information Center

    Gandy, Gerald L.

    1973-01-01

    Investigated birth order differences and the vocational interests of 150 male college students, making use of the Strong Vocational Interest Blank. Sibling sex and interaction effects were also investigated. (DP)

  7. Cation Ordering in Layered Nickelates

    NASA Astrophysics Data System (ADS)

    Nelson-Cheeseman, Brittany; Zhou, Hua; Cammarata, Antonio; Hoffman, Jason; Balachandran, Prasanna; Rondinelli, James; Bhattacharya, Anand

    2013-03-01

    The single layer Ruddlesden-Popper nickelates present a model system to understand how the effects of digital dopant cation ordering may affect the properties of 2-dimensional conducting sheets. We investigate the effects of aliovalent A-site cation order on LaSrNiO4 films. Using molecular beam epitaxy, we interleave full layers of SrO and LaO in a series of chemically equivalent films, varying the pattern of SrO and LaO layers relative to the NiO2 layers. Through synchrotron surface x-ray diffraction and Coherant Bragg Rod Analysis (COBRA), we directly investigate the A-site cation order and the resulting atomic displacements for each ordering pattern. We correlate these results with theoretical calculations and transport measurements of the layered nickelate films.

  8. Supersymmetric fifth order evolution equations

    SciTech Connect

    Tian, K.; Liu, Q. P.

    2010-03-08

    This paper considers supersymmetric fifth order evolution equations. Within the framework of symmetry approach, we give a list containing six equations, which are (potentially) integrable systems. Among these equations, the most interesting ones include a supersymmetric Sawada-Kotera equation and a novel supersymmetric fifth order KdV equation. For the latter, we supply some properties such as a Hamiltonian structures and a possible recursion operator.

  9. Life from an orderly cosmos

    NASA Astrophysics Data System (ADS)

    Fox, Sidney W.

    1980-12-01

    Recent astrophysical studies suggest a high degree of order in the inanimate universe, stemming from cosmic beginnings. This state is consistent with the nonrandomness observed experimentally in the thermal polymers of amino acids that figure as an early inanimate stage in organic evolution. The various stages in inanimate matter, protocells, and evolved cells and the degree of order that they represent comport with the second law of thermodynamics on a cosmic scale.

  10. Life from an orderly cosmos.

    PubMed

    Fox, S W

    1980-12-01

    Recent astrophysical studies suggest a high degree of order in the inanimate universe, stemming from cosmic beginnings. This state is consistent with the nonrandomness observed experimentally in the thermal polymers of amino acids that figure as an early inanimate stage in organic evolution. The various stages in inanimate matter, protocells, and evolved cells and the degree of order that they represent comport with the second law of thermodynamics on a cosmic scale. PMID:7231562

  11. Complete normal ordering 1: Foundations

    NASA Astrophysics Data System (ADS)

    Ellis, John; Mavromatos, Nick E.; Skliros, Dimitri P.

    2016-08-01

    We introduce a new prescription for quantising scalar field theories (in generic spacetime dimension and background) perturbatively around a true minimum of the full quantum effective action, which is to 'complete normal order' the bare action of interest. When the true vacuum of the theory is located at zero field value, the key property of this prescription is the automatic cancellation, to any finite order in perturbation theory, of all tadpole and, more generally, all 'cephalopod' Feynman diagrams. The latter are connected diagrams that can be disconnected into two pieces by cutting one internal vertex, with either one or both pieces free from external lines. In addition, this procedure of 'complete normal ordering' (which is an extension of the standard field theory definition of normal ordering) reduces by a substantial factor the number of Feynman diagrams to be calculated at any given loop order. We illustrate explicitly the complete normal ordering procedure and the cancellation of cephalopod diagrams in scalar field theories with non-derivative interactions, and by using a point splitting 'trick' we extend this result to theories with derivative interactions, such as those appearing as non-linear σ-models in the world-sheet formulation of string theory. We focus here on theories with trivial vacua, generalising the discussion to non-trivial vacua in a follow-up paper.

  12. Computerized provider order entry systems.

    PubMed

    2001-01-01

    Computerized provider order entry (CPOE) systems are designed to replace a hospital's paper-based ordering system. They allow users to electronically write the full range of orders, maintain an online medication administration record, and review changes made to an order by successive personnel. They also offer safety alerts that are triggered when an unsafe order (such as for a duplicate drug therapy) is entered, as well as clinical decision support to guide caregivers to less expensive alternatives or to choices that better fit established hospital protocols. CPOE systems can, when correctly configured, markedly increase efficiency and improve patient safety and patient care. However, facilities need to recognize that currently available CPOE systems require a tremendous amount of time and effort to be spent in customization before their safety and clinical support features can be effectively implemented. What's more, even after they've been customized, the systems may still allow certain unsafe orders to be entered. Thus, CPOE systems are not currently a quick or easy remedy for medical errors. ECRI's Evaluation of CPOE systems--conducted in collaboration with the Institute for Safe Medication Practices (ISMP)--discusses these and other related issues. It also examines and compares CPOE systems from three suppliers: Eclipsys Corp., IDX Systems Corp., and Siemens Medical Solutions Health Services Corp. Our testing focuses primarily on the systems' interfacing capabilities, patient safeguards, and ease of use. PMID:11696968

  13. Order-order transitions in ABC triblock nanostructures

    SciTech Connect

    Zhong-Ren Chen; Kornfield, J.A.; Smith, S.; Satkowski, M.

    1996-12-31

    This report discusses a triblock copolymer of isoprene I, styrene S, and a random copolymer of styrene and isoprene. Optical methods are used to examine flow-induced alignment kinetics and final alignment state; nanostructures and global order are also studied.

  14. Using High-Order Methods on Lower-Order Geometries

    NASA Technical Reports Server (NTRS)

    Casper, Jay

    1997-01-01

    The desire to obtain acoustic information from the numerical solution of a nonlinear system of equations is a demanding proposition for a computational algorithm. High-order accuracy is required for the propagation of high-frequency, low-amplitude waves. The accuracy of an algorithm can be compromised by low-order errors that naturally occur in the solution of a particular problem. Such errors arise from two sources: the presence of discontinuities in the flow field or because the geometry on which the problem is defined is not everywhere smooth to the order of the scheme. The performance of high-order accurate essentially non-oscillatory (ENO) schemes on piecewise smooth solutions is well documented. Herein, the performance of these methods on smooth solutions defined on piecewise smooth geometries is investigated. The propagation of sound in a quasi-one-dimensional nozzle is considered as a test case. Some of the issues involved in the extension to two spatial dimensions are discussed.

  15. A Law of Order: Word Order Change in Classical Aztec

    ERIC Educational Resources Information Center

    Steele, Susan M.

    1976-01-01

    The verb in Classical Aztec is slowly moving from the end of the sentence to the beginning due to the attraction of sentence initial modal particles to the verb. Not only the function but also the position of elements should be examined to account for word-order change. (SCC)

  16. Order-parameter scaling in fluctuation-dominated phase ordering.

    PubMed

    Kapri, Rajeev; Bandyopadhyay, Malay; Barma, Mustansir

    2016-01-01

    In systems exhibiting fluctuation-dominated phase ordering, a single order parameter does not suffice to characterize the order, and it is necessary to monitor a larger set. For hard-core sliding particles on a fluctuating surface and the related coarse-grained depth (CD) models, this set comprises the long-wavelength Fourier components of the density profile, which capture the breakup and remerging of particle-rich regions. We study both static and dynamic scaling laws obeyed by the Fourier modes Q_{mL} and find that the mean value obeys the static scaling law 〈Q_{mL}〉∼L^{-ϕ}f(m/L) with ϕ≃2/3 and ϕ≃3/5 for Edwards-Wilkinson (EW) and Kardar-Parisi-Zhang (KPZ) surface evolution, respectively, and ϕ≃3/4 for the CD model. The full probability distribution P(Q_{mL}) exhibits scaling as well. Further, time-dependent correlation functions such as the steady-state autocorrelation and cross-correlations of order-parameter components are scaling functions of t/L^{z}, where L is the system size and z is the dynamic exponent, with z=2 for EW and z=3/2 for KPZ surface evolution. In addition we find that the CD model shows temporal intermittency, manifested in the dynamical structure functions of the density and the weak divergence of the flatness as the scaled time approaches 0. PMID:26871034

  17. Determining Reduced Order Models for Optimal Stochastic Reduced Order Models

    SciTech Connect

    Bonney, Matthew S.; Brake, Matthew R.W.

    2015-08-01

    The use of parameterized reduced order models(PROMs) within the stochastic reduced order model (SROM) framework is a logical progression for both methods. In this report, five different parameterized reduced order models are selected and critiqued against the other models along with truth model for the example of the Brake-Reuss beam. The models are: a Taylor series using finite difference, a proper orthogonal decomposition of the the output, a Craig-Bampton representation of the model, a method that uses Hyper-Dual numbers to determine the sensitivities, and a Meta-Model method that uses the Hyper-Dual results and constructs a polynomial curve to better represent the output data. The methods are compared against a parameter sweep and a distribution propagation where the first four statistical moments are used as a comparison. Each method produces very accurate results with the Craig-Bampton reduction having the least accurate results. The models are also compared based on time requirements for the evaluation of each model where the Meta- Model requires the least amount of time for computation by a significant amount. Each of the five models provided accurate results in a reasonable time frame. The determination of which model to use is dependent on the availability of the high-fidelity model and how many evaluations can be performed. Analysis of the output distribution is examined by using a large Monte-Carlo simulation along with a reduced simulation using Latin Hypercube and the stochastic reduced order model sampling technique. Both techniques produced accurate results. The stochastic reduced order modeling technique produced less error when compared to an exhaustive sampling for the majority of methods.

  18. Temporal order judgment in dyslexia.

    PubMed

    Jaśkowski, Piotr; Rusiak, Patrycja

    2008-01-01

    Hari et al. (Brain 174:1373-1380, 2001) demonstrated that dyslexics showed a sluggish attention capture in both visual hemifields. Additionally, they indicated a left-right asymmetry in the perception of temporal order of two visual stimuli (they performed worse than controls only if the stimulus in the left hemifield preceded that in right hemifield). They suggested that a left-sided minineglect is associated with dyslexia. We hypothesized that if a kind of neglect syndrome is responsible for the asymmetry they found, dyslexics should not only show a left-right asymmetry in temporal order judgment of two laterally presented stimuli but also perform equally well as controls when the stimuli are vertically aligned. Our results indicated that in both tasks dyslexics performed generally worse than normal readers. The results suggest that dyslexics suffer from a more general problem of order discrimination. PMID:17028891

  19. Ordering states with coherence measures

    NASA Astrophysics Data System (ADS)

    Liu, C. L.; Yu, Xiao-Dong; Xu, G. F.; Tong, D. M.

    2016-07-01

    The quantification of quantum coherence has attracted a growing attention, and based on various physical contexts, several coherence measures have been put forward. An interesting question is whether these coherence measures give the same ordering when they are used to quantify the coherence of quantum states. In this paper, we consider the two well-known coherence measures, the l_1 norm of coherence and the relative entropy of coherence, to show that there are the states for which the two measures give a different ordering. Our analysis can be extended to other coherence measures, and as an illustration of the extension we further consider the formation of coherence to show that the l_1 norm of coherence and the formation of coherence, as well as the relative entropy of coherence and the coherence of formation, do not give the same ordering too.

  20. Judicial review of conservation orders

    SciTech Connect

    Brown, R.L. Jr.

    1983-05-01

    Judicial review of orders issued by the Commissioner of Conservation may be sought under the authority of both Louisiana Revised Statutes 49:964 and Louisiana Revised Statutes 30:12. These statutes differ with respect to who may bring an action, the form of relief the reviewing court may grant, the scope of the evidence considered by the reviewing court, and the standards on the burden of proof. The application of laches under 30:12 is inconsistent with the 30-day delay periods provided by 49:964, and it is unworkable to the extent that it ignores the underlying need for finality of conservation orders. The continuing threat of subsequent court review destroys the credibility of the orders. Finality could be achieved under the current use of latches if a judicial determination established a definite length of reasonable delay. It is up to the legislature to correct the uncertainty introduced by 30:12. 91 references.

  1. Direct Observation of Magnetic Field Induced Ferroelectric Domain Evolution in Self-Assembled Quasi (0-3) BiFeO3-CoFe2O4 Thin Films.

    PubMed

    Li, Linglong; Lu, Lu; Zhang, Dawei; Su, Ran; Yang, Guang; Zhai, Junyi; Yang, Yaodong

    2016-01-13

    Strain-mediated magnetoelectric (ME) coupling effect is expected in self-assembly heterostructures engineered by ferroelectric and ferromagnetic materials, contributing to the enhanced overall magnetoelectric effect. Microstructures as well as the connectivity configuration are considered to play a significant role in achieving efficient magnetoelectric properties. Different from the conventional (1-3) and (2-2) type composite films, we fabricate BiFeO3-CoFe2O4 (BFO-CFO) composite thin films with a novel quasi (0-3) type connectivity via a dual-target pulsed laser deposition process. The self-assembly growth mechanism has been studied, which demonstrates that the perovskite (BFO) matrix segments the connectivity of spinel (CFO) resulting in a quasi (0-3) composite. Direct observation of ferroelectric domain wall motion under external magnetic fields proves a strong magnetoelectric coupling effect in these (0-3) thin films. Our preliminary findings reveal the promising application potential of this new structure as multiferroic domain wall devices. PMID:26698906

  2. Transport Properties of 2D-Electron Gas in a InGaAs/GaAs DQW in a Vicinity of Low Magnetic-Field-Induced Insulator-Quantum Hall Liquid Transition

    NASA Astrophysics Data System (ADS)

    Arapov, Yu. G.; Yakunin, M. V.; Gudina, S. V.; Harus, G. I.; Neverov, V. N.; Shelushinina, N. G.; Podgornyh, S. M.; Uskova, E. A.; Zvonkov, B. N.

    2007-04-01

    The resistivity ρ of low mobility dilute 2D-elecron gas in a InGaAs/GaAs double quantum well (DQW) exhibits the monotonic "insulating-like" temperature dependence (dρ/dT < 0) at T = 1.8-70K in zero magnetic field. This temperature interval corresponds to a ballistic regime (kBTτ/ℏ > 0.1) for our samples. We observed the coexistence of both the quantum Hall (QH) effect for the filling factors v = 2, 4 and the low magnetic field insulator — QH liquid (with v = 10) transition.

  3. Risk attitudes and birth order.

    PubMed

    Krause, Philipp; Heindl, Johannes; Jung, Andreas; Langguth, Berthold; Hajak, Göran; Sand, Philipp G

    2014-07-01

    Risk attitudes play important roles in health behavior and everyday decision making. It is unclear, however, whether these attitudes can be predicted from birth order. We investigated 200 mostly male volunteers from two distinct settings. After correcting for multiple comparisons, for the number of siblings and for confounding by gender, ordinal position predicted perception of health-related risks among participants in extreme sports (p < .01). However, the direction of the effect contradicted Adlerian theory. Except for alcohol consumption, these findings extended to self-reported risk behavior. Together, the data call for a cautious stand on the impact of birth order on risk attitudes. PMID:23520357

  4. Ordering Multiple Soft Gluon Emissions.

    PubMed

    Ángeles Martínez, René; Forshaw, Jeffrey R; Seymour, Michael H

    2016-05-27

    We present an expression for the QCD amplitude for a general hard scattering process with any number of soft gluon emissions, to one-loop accuracy. The amplitude is written in two different but equivalent ways: as a product of operators ordered in dipole transverse momentum and as a product of loop-expanded currents. We hope that these results will help in the development of an all-orders algorithm for multiple emissions that includes the full color structure and both the real and imaginary contributions to the amplitude. PMID:27284651

  5. DNR Orders and School Responsibility.

    ERIC Educational Resources Information Center

    Sewall, Angela Maynard; Balkman, Kathy

    This paper discusses the legal and ethical questions surrounding "Do Not Resuscitate" (DNR) orders in the school environment. It begins by reviewing federal and state case law that addresses the appropriateness of medical services and the responsibility of schools in terms of provision of medical services. The review finds that when medical-like…

  6. Generalized high order compact methods.

    SciTech Connect

    Spotz, William F.; Kominiarczuk, Jakub

    2010-09-01

    The fundamental ideas of the high order compact method are combined with the generalized finite difference method. The result is a finite difference method that works on unstructured, nonuniform grids, and is more accurate than one would classically expect from the number of grid points employed.

  7. Suffix Ordering and Morphological Processing

    ERIC Educational Resources Information Center

    Plag, Ingo; Baayen, Harald

    2009-01-01

    There is a long-standing debate about the principles constraining the combinatorial properties of suffixes. Hay 2002 and Hay & Plag 2004 proposed a model in which suffixes can be ordered along a hierarchy of processing complexity. We show that this model generalizes to a larger set of suffixes, and we provide independent evidence supporting the…

  8. Peacekeeping. Perspectives in World Order.

    ERIC Educational Resources Information Center

    Fraenkel, Jack R., Ed.; And Others

    This pamphlet, intended for senior high classroom use, defines war, peace, and peacekeeping systems; discusses the destructiveness of war; and proposes the case study method for studying world order. The major portion of the booklet explores ways of peacekeeping through analysis of four different models: collective security, collective force,…

  9. Moral Order and the Humanities.

    ERIC Educational Resources Information Center

    Howard, Thomas

    1980-01-01

    Argues that a society without reverence for myths and history inevitably falls prone to chaos and evil, pointing to abortion, Andy Warhol's celebrity, and Woodstock as evidence of this disintegration of society. Proposes that humanities education expose students to human experience based on some awesome and fixed moral order. (AYC)

  10. Nanoparticle Order through Entropic Confinement

    NASA Astrophysics Data System (ADS)

    Zhang, Ren; Lee, Bongjoon; Stafford, Christopher; Douglas, Jack; Bockstaller, Michael; Karim, Alamgir

    As has been addressed in colloidal science, visual order transitions can be achieved with entropy contributions alone. Herein, entropy-driven ordering of nanoparticle (NP) structures is generated where entropy increase and visual order are achieved simultaneously. We study an ``athermal'' NP-polymer blends where NPs are densely grafted with polymer brush of the same chemical composition as the polymer matrix. Visual order of the NPs is induced by geometrically confining the thin film blends with meso-scale topographic patterns. When the residual layer thickness of the patterned blend films approaches the nanoparticle dimension, exclusive segregation of NPs to less confining imprinted mesa region occurs. This preferential segregation of NPs, defined by partition coefficient K = 0, is attributed to purely entropic penalty, where K denotes the particle density ratio at highly confined residual layer to that at mesa region. We further demonstrate K is fully tunable and even invertible with increasing matrix chain dimension. The associated entropic free energy change (ΔF = - ln K) is calculated to explain NP segregation preference. Accordingly, variation of residual layer thickness and polymer matrix molecule size can both affect NP distribution among patterned thick and thin regions.

  11. Spatial Processes in Linear Ordering

    ERIC Educational Resources Information Center

    von Hecker, Ulrich; Klauer, Karl Christoph; Wolf, Lukas; Fazilat-Pour, Masoud

    2016-01-01

    Memory performance in linear order reasoning tasks (A > B, B > C, C > D, etc.) shows quicker, and more accurate responses to queries on wider (AD) than narrower (AB) pairs on a hypothetical linear mental model (A -- B -- C -- D). While indicative of an analogue representation, research so far did not provide positive evidence for spatial…

  12. Time ordering of gene coexpression.

    PubMed

    Leng, Xiaoyan; Müller, Hans-Georg

    2006-10-01

    Temporal microarray gene expression profiles allow characterization of gene function through time dynamics of gene coexpression within the same genetic pathway. In this paper, we define and estimate a global time shift characteristic for each gene via least squares, inferred from pairwise curve alignments. These time shift characteristics of individual genes reflect a time ordering that is derived from ob- served temporal gene expression profiles. Once these time shift characteristics are obtained for each gene, they can be entered into further analyses, such as clustering. We illustrate the proposed methodology using Drosophila embryonic development and yeast cell-cycle gene expression profiles, as well as simulations. Feasibility is demonstrated through the successful recovery of time ordering. Estimated time shifts for Drosophila maternal and zygotic genes provide excellent discrimination between these two categories and confirm known genetic pathways through the time order of gene expression. The application to yeast cell-cycle data establishes a natural time order of genes that is in line with cell-cycle phases. The method does not require periodicity of gene expression profiles. Asymptotic justifications are also provided. PMID:16495429

  13. Macrojunctions ordering in polyelectrolyte hydrogels

    NASA Astrophysics Data System (ADS)

    Török, Gy; Lebedev, V. T.; Cser, L.; Buyanov, A. L.; Revelskaya, L. G.

    2000-03-01

    We studied the structure of polyelectrolyte hydrogels of sodium polyacrylate cross-linked by macromolecular allyldextran (supergels). Using high-resolution SANS we have found the specific ordering of macrojunctions (structure's period ∼130 nm) that may be reliable for the network's anomaly swelling.

  14. Reduced Order Modeling Incompressible Flows

    NASA Technical Reports Server (NTRS)

    Helenbrook, B. T.

    2010-01-01

    The details: a) Need stable numerical methods; b) Round off error can be considerable; c) Not convinced modes are correct for incompressible flow. Nonetheless, can derive compact and accurate reduced-order models. Can be used to generate actuator models or full flow-field models

  15. Weighted order statistic classifiers with large rank-order margin.

    SciTech Connect

    Porter, R. B.; Hush, D. R.; Theiler, J. P.; Gokhale, M.

    2003-01-01

    We describe how Stack Filters and Weighted Order Statistic function classes can be used for classification problems. This leads to a new design criteria for linear classifiers when inputs are binary-valued and weights are positive . We present a rank-based measure of margin that can be directly optimized as a standard linear program and investigate its effect on generalization error with experiment. Our approach can robustly combine large numbers of base hypothesis and easily implement known priors through regularization.

  16. Symbols of a cosmic order

    NASA Astrophysics Data System (ADS)

    Madjid, F. Hadi; Myers, John M.

    2016-10-01

    The world runs on networks over which signals communicate sequences of symbols, e.g. numerals. Examining both engineered and natural communications networks reveals an unsuspected order that depends on contact with an unpredictable entity. This order has three roots. The first is a proof within quantum theory that no evidence can ever determine its explanation, so that an agent choosing an explanation must do so unpredictably. The second root is the showing that clocks that step computers do not "tell time" but serve as self-adjusting symbol-handling agents that regulate "logically synchronized" motion in response to unpredictable disturbances. Such a clock-agent has a certain independence as well as the capacity to communicate via unpredictable symbols with other clock-agents and to adjust its own tick rate in response to that communication. The third root is the noticing of unpredictable symbol exchange in natural systems, including the transmission of symbols found in molecular biology. We introduce a symbol-handling agent as a role played in some cases by a person, for example a physicist who chooses an explanation of given experimental outcomes, and in other cases by some other biological entity, and in still other cases by an inanimate device, such as a computer-based detector used in physical measurements. While we forbear to try to explain the propensity of agents at all levels from cells to civilizations to form and operate networks of logically synchronized symbol-handling agents, we point to this propensity as an overlooked cosmic order, an order structured by the unpredictability ensuing from the proof. Appreciating the cosmic order leads to a conception of agency that replaces volition by unpredictability and reconceives the notion of objectivity in a way that makes a place for agency in the world as described by physics. Some specific implications for physics are outlined.

  17. Higher order stationary subspace analysis

    NASA Astrophysics Data System (ADS)

    Panknin, Danny; von Bünau, Paul; Kawanabe, Motoaki; Meinecke, Frank C.; Müller, Klaus-Robert

    2016-03-01

    Non-stationarity in data is an ubiquitous problem in signal processing. The recent stationary subspace analysis procedure (SSA) has enabled to decompose such data into a stationary subspace and a non-stationary part respectively. Algorithmically only weak non- stationarities could be tackled by SSA. The present paper takes the conceptual step generalizing from the use of first and second moments as in SSA to higher order moments, thus defining the proposed higher order stationary subspace analysis procedure (HOSSA). The paper derives the novel procedure and shows simulations. An obvious trade-off between the necessity of estimating higher moments and the accuracy and robustness with which they can be estimated is observed. In an ideal setting of plenty of data where higher moment information is dominating our novel approach can win against standard SSA. However, with limited data, even though higher moments actually dominate the underlying data, still SSA may arrive on par.

  18. Recent advances in ordered intermetallics

    SciTech Connect

    Liu, C.T.

    1994-12-31

    Ordered intermetallic alloys based on aluminides and silicides offer many advantages for structural use at high temperatures in hostile environments. Attractive properties include excellent oxidation and corrosion resistance, light weight, and superior strength at high temperatures. The major concern for structural use of intermetallics was their low ductility and poor fracture resistance at ambient temperatures. For the past 10 years, considerable effort was devoted to R&D of ordered intermetallic alloys, and progress has been made on understanding intrinsic and extrinsic factors controlling brittle fracture in intermetallic alloys based on aluminides and silicides. Parallel effort on alloy design has led to the development of a number of ductile and strong intermetallic alloys based on Ni{sub 3}Al, NiAl, Fe{sub 3}Al, FeAl, Ti{sub 3}Al, and TiAl systems for structural applications.

  19. Umbilic Lines in Orientational Order

    NASA Astrophysics Data System (ADS)

    Machon, Thomas; Alexander, Gareth P.

    2016-01-01

    Three-dimensional orientational order in systems whose ground states possess nonzero gradients typically exhibits linelike structures or defects: λ lines in cholesterics or Skyrmion tubes in ferromagnets, for example. Here, we show that such lines can be identified as a set of natural geometric singularities in a unit vector field, the generalization of the umbilic points of a surface. We characterize these lines in terms of the natural vector bundles that the order defines and show that they give a way to localize and identify Skyrmion distortions in chiral materials—in particular, that they supply a natural representative of the Poincaré dual of the cocycle describing the topology. Their global structure leads to the definition of a self-linking number and helicity integral which relates the linking of umbilic lines to the Hopf invariant of the texture.

  20. Second-Order Footsteps Illusions

    PubMed Central

    Anstis, Stuart

    2015-01-01

    In the “footsteps illusion”, light and dark squares travel at constant speed across black and white stripes. The squares appear to move faster and slower as their contrast against the stripes varies. We now demonstrate some second-order footsteps illusions, in which all edges are defined by colors or textures—even though luminance-based neural motion detectors are blind to such edges. PMID:27551366

  1. Second-Order Footsteps Illusions.

    PubMed

    Kitaoka, Akiyoshi; Anstis, Stuart

    2015-12-01

    In the "footsteps illusion", light and dark squares travel at constant speed across black and white stripes. The squares appear to move faster and slower as their contrast against the stripes varies. We now demonstrate some second-order footsteps illusions, in which all edges are defined by colors or textures-even though luminance-based neural motion detectors are blind to such edges. PMID:27551366

  2. Digital first order hold circuit

    NASA Technical Reports Server (NTRS)

    Chan, Fred N. (Inventor); Wensley, Gerald J. (Inventor)

    1989-01-01

    There is provided a digitally controlled first order hold circuit and waveform synthesizer for digitally controlling the representation of a function over an approximation interval. In accordance with the operation of the invention, the first order hold circuit and waveform generator receives a digital data input signal which contains initial condition data, up/down data, and slope data for the approximation interval. The initial condition data is loaded into an up/down counter which is incremented using counting data at a rate depending on the value of the slope data and in a direction depending on the value of the up-down data. In order to minimize delays arising from data acquistion, two frequency synthesizer circuits are provided such that one frequency synthesizer provides counting data while the other frequency synthesizer receives slope data. During alternating intervals, the other frequency synthesizer circuit provides counting data while the other circuit receives slope data. In addition, long length data input signals covering a plurality of approximation intervals are provided to reduce the demands on a main system central processing unit.

  3. RHO—Radiation Hybrid Ordering

    PubMed Central

    Ben-Dor, Amir; Chor, Benny; Pelleg, Dan

    2000-01-01

    Radiation hybrid (RH) mapping is a somatic cell technique that is used for ordering markers along a chromosome and estimating the physical distances between them. With the advent of this mapping technique, analyzing the experimental data is becoming a challenging and demanding computational task. In this paper we present the software package RHO (radiation hybrid ordering). The package implements a number of heuristics that attempt to order genomic markers along a chromosome, given as input the results of an RH experiment. The heuristics are based on reducing an appropriate optimization problem to the traveling salesman problem (TSP). The reduced optimization problem is either the nonparametric obligate chromosome breaks (OCBs) or the parametric maximum likelihood estimation (MLE). We tested our package on both simulated and publicly available RH data. For synthetic RH data, the reconstructed markers' permutation is very close to the original permutation, even with fairly high error rates. For real data we used the framework markers' data from the Whitehead Institute maps. For most of the chromosomes (18 out of 23), there is a perfect agreement or nearly perfect agreement (reversal of chromosome arm or arms) between our maps and the Whitehead framework maps. For the remaining five chromosomes, our maps improve on the Whitehead framework maps with respect to both optimization criteria, having higher likelihood and fewer breakpoints. For three chromosomes, the results differ significantly (lod score >1.75), with chromosome 2 having the largest improvement (lod score 3.776). PMID:10720577

  4. 7 CFR 1214.12 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE CHRISTMAS TREE PROMOTION, RESEARCH, AND INFORMATION ORDER Christmas Tree Promotion, Research, and Information Order Definitions §...

  5. 7 CFR 1214.12 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE CHRISTMAS TREE PROMOTION, RESEARCH, AND INFORMATION ORDER Christmas Tree Promotion, Research, and Information Order Definitions §...

  6. 7 CFR 1214.12 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE CHRISTMAS TREE PROMOTION, RESEARCH, AND INFORMATION ORDER Christmas Tree Promotion, Research, and Information Order Definitions §...

  7. 19 CFR 210.75 - Proceedings to enforce exclusion orders, cease and desist orders, consent orders, and other...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND... provision of an exclusion order, cease and desist order, or consent order. Such matters may be handled by... with the terms of an exclusion order, cease and desist order, or consent order, or any part...

  8. 19 CFR 210.75 - Proceedings to enforce exclusion orders, cease and desist orders, consent orders, and other...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND... provision of an exclusion order, cease and desist order, or consent order. Such matters may be handled by... with the terms of an exclusion order, cease and desist order, or consent order, or any part...

  9. 19 CFR 210.75 - Proceedings to enforce exclusion orders, cease and desist orders, consent orders, and other...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND... provision of an exclusion order, cease and desist order, or consent order. Such matters may be handled by... with the terms of an exclusion order, cease and desist order, or consent order, or any part...

  10. 19 CFR 210.75 - Proceedings to enforce exclusion orders, cease and desist orders, consent orders, and other...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND... provision of an exclusion order, cease and desist order, or consent order. Such matters may be handled by... with the terms of an exclusion order, cease and desist order, or consent order, or any part...

  11. 19 CFR 210.75 - Proceedings to enforce exclusion orders, cease and desist orders, consent orders, and other...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND... provision of an exclusion order, cease and desist order, or consent order. Such matters may be handled by... with the terms of an exclusion order, cease and desist order, or consent order, or any part...

  12. Fourth order deformed general relativity

    NASA Astrophysics Data System (ADS)

    Cuttell, Peter D.; Sakellariadou, Mairi

    2014-11-01

    Whenever the condition of anomaly freedom is imposed within the framework of effective approaches to loop quantum cosmology, one seems to conclude that a deformation of general covariance is required. Here, starting from a general deformation we regain an effective gravitational Lagrangian including terms up to fourth order in extrinsic curvature. We subsequently constrain the form of the corrections for the homogeneous case, and then investigate the conditions for the occurrence of a big bounce and the realization of an inflationary era, in the presence of a perfect fluid or scalar field.

  13. Third-order RKR procedure

    NASA Astrophysics Data System (ADS)

    Pardo, A.; Camacho, J. J.; Poyato, J. M. L.; Fernandez-Alonso, J. I.

    1986-03-01

    Potential energy curves for the X 1Σ +state of 6LiH, 7LiH and 6LiD, 7LiD molecules have been calculated by the third-order RKR inversion procedure by including the Kaise correction. The results are in agreement with previously obtained curves by other authors using differents methods. As a check, the exact vibrational eigenfunctions, appropriate to these potentials, are obtained by direct numerical solutions of the radical Schrödinger equation.

  14. Multiferroicity due to Charge Ordering

    NASA Astrophysics Data System (ADS)

    van den Brink, Jeroen

    2012-02-01

    In this contribution I discuss multiferroicity that is driven by different forms of charge ordering, presenting first the generic mechanisms by which charge ordering can induce ferroelectricity in magnetic systems. In type-I multiferroics [1], ferroelectricity and magnetism have different origins and occur at different temperatures. There is a number of specific classes of materials for which this is relevant. Discussed will be in some detail (i) perovskite manganites of the type (PrCa)MnO3 [2,3], (ii) the complex and interesting situation in magnetite Fe3O4, (iii) strongly ferroelectric frustrated LuFe2O4 and (iv) an example of a quasi-one-dimensional organic system [4]. In type-II multiferroics [1], ferroelectricity is completely due to magnetism, but with charge ordering playing an important role [5], such as (v) multiferroic Ca3CoMnO6, (vi) possible ferroelectricity in rare earth perovskite nickelates of the type RNiO3 [6,7], (vii) multiferroic properties of manganites of the type RMn2O5 [8], (viii) perovskite manganites with magnetic E-type ordering. [4pt] [1] J. van den Brink and D. Khomskii, J. Phys.: Condens. Matter 20, 434217 (2008).[0pt] [2] D.V. Efremov, J. van den Brink and D.I. Khomskii, Nature Materials 3, 853 (2004).[0pt] [3] G. Giovannetti, S. Kumar, J. van den Brink, S. Picozzi, Phys. Rev. Lett. 103, 037601 (2009).[0pt] [4] G. Giovannetti, S. Kumar, A. Stroppa, J. van den Brink and S. Picozzi, Phys. Rev. Lett. 103, 266401 (2009). [0pt] [5] J. Betouras G. Giovannetti and J. van den Brink, Phys. Rev. Lett. 98, 257602 (2007).[0pt] [6] G. Giovannetti, S. Kumar, D. Khomskii, S. Picozzi and J. van den Brink, Phys. Rev. Lett. 103, 156401 (2009).[0pt] [7] S. Kumar, G. Giovannetti, J. van den Brink and S. Picozzi, Phys. Rev. B 82, 134429 (2010).[0pt] [8] G. Giovannetti and J. van den Brink, Phys. Rev. Lett. 100, 227603 (2008).

  15. Partial order of quantum effects

    NASA Astrophysics Data System (ADS)

    Lahti, Pekka J.; Ma̧czynski, Maciej J.

    1995-04-01

    The set of effects is not a lattice with respect to its natural order. Projection operators do have the greatest lower bounds (and the least upper bounds) in that set, but there are also other (incomparable) effects which share this property. However, the coexistence, the commutativity, and the regularity of a pair of effects are not sufficient for the existence of their infima and suprema. The structure of the range of an observable (as a normalized POV measure) can vary from that of a commutative Boolean to a noncommutative non-Boolean subset of effects.

  16. The New International Economic Order

    NASA Astrophysics Data System (ADS)

    Streeten, Paul P.

    1982-12-01

    Starting from a premise of optimism, this paper first sets out the essence of the proposed New International Economic Order and then traces its origins and interpretations. It examines the options available for different groups of the developing countries and those open to the constructively-minded of the industrialized states. It also explores what avenues there might be for furthering common interests, for countering hidden biases which might be operating against developing states, and for avoiding unnecessary conflicts. The paper ends with a plea for the consideration of the higher interests both of the nation-state and of the human race.

  17. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    SciTech Connect

    de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B. )

    1991-01-29

    Deuterium nuclear magnetic resonance ({sup 2}H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the {beta}-position of the serine moiety ((2-{sup 2}H)DOPS) or at the 11-position of the acyl chains ((11,11-{sup 2}H{sub 2})DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both (2-{sup 2}H)DOPS and (11,11-{sup 2}H{sub 2})DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine){sub 100}, which were included for reasons of comparison, reveal increased {Delta}v{sub q} values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component {sup 2}H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. {sup 2}H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides.

  18. 7 CFR 1280.113 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Order. 1280.113 Section 1280.113 Agriculture... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE LAMB PROMOTION, RESEARCH, AND INFORMATION ORDER Lamb Promotion, Research, and Information Order Definitions § 1280.113 Order. Order means...

  19. 7 CFR 1280.113 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Order. 1280.113 Section 1280.113 Agriculture... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE LAMB PROMOTION, RESEARCH, AND INFORMATION ORDER Lamb Promotion, Research, and Information Order Definitions § 1280.113 Order. Order means...

  20. 39 CFR 952.28 - Orders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Orders. 952.28 Section 952.28 Postal Service... AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail to a... order to be published in the Postal Bulletin and cause the order to be transmitted to such...

  1. 39 CFR 952.28 - Orders.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 39 Postal Service 1 2012-07-01 2012-07-01 false Orders. 952.28 Section 952.28 Postal Service... AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail to... order to be published in the Postal Bulletin and cause the order to be transmitted to such...

  2. 7 CFR 1280.113 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Order. 1280.113 Section 1280.113 Agriculture... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE LAMB PROMOTION, RESEARCH, AND INFORMATION ORDER Lamb Promotion, Research, and Information Order Definitions § 1280.113 Order. Order means...

  3. 39 CFR 952.28 - Orders.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 39 Postal Service 1 2011-07-01 2011-07-01 false Orders. 952.28 Section 952.28 Postal Service... AND LOTTERY ORDERS (EFF. UNTIL 7-22-2011) § 952.28 Orders. (a) If an order is issued which prohibits... shall cause notice of the order to be published in the Postal Bulletin and cause the order to...

  4. 7 CFR 1280.113 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Order. 1280.113 Section 1280.113 Agriculture... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE LAMB PROMOTION, RESEARCH, AND INFORMATION ORDER Lamb Promotion, Research, and Information Order Definitions § 1280.113 Order. Order means...

  5. 39 CFR 952.28 - Orders.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Orders. 952.28 Section 952.28 Postal Service... AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail to... order to be published in the Postal Bulletin and cause the order to be transmitted to such...

  6. 7 CFR 1280.113 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Order. 1280.113 Section 1280.113 Agriculture... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE LAMB PROMOTION, RESEARCH, AND INFORMATION ORDER Lamb Promotion, Research, and Information Order Definitions § 1280.113 Order. Order means...

  7. 40 CFR 22.31 - Final order.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Final order. 22.31 Section 22.31... PERMITS Final Order § 22.31 Final order. (a) Effect of final order. A final order constitutes the final Agency action in a proceeding. The final order shall not in any case affect the right of the Agency...

  8. 39 CFR 952.28 - Orders.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 39 Postal Service 1 2013-07-01 2013-07-01 false Orders. 952.28 Section 952.28 Postal Service... AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail to... order to be published in the Postal Bulletin and cause the order to be transmitted to such...

  9. The Fitness of Genomic Order

    NASA Astrophysics Data System (ADS)

    Zhang, Qiucen; Vyawahare, Saurabh; Austin, Robert

    2012-02-01

    Most bacteria have a single circular chromosome that can range in size from 160,000 to 12,200,000 base pairs. Considering the typical gene density, i.e. 1 gene per 1,000 base pairs, both the number of genes and the ways to arrange are huge. Intuitively, the arrangement of genes on the circle is not important if all of them can be replicated. However, there is typically one origin of replication, and when bacteria is attacked by genotoxic stress during replication, the whole replication process can not be finished. As a result, which gene is replicated first, which is second, ..., becomes very important. Experimentally, we found a broad increase of DNA copy number near the origin of replication (OriC) of bacteria E.coli (˜3200 genes) under genotoxic stress. Since the genes near OriC are mostly efflux pump genes, we propose that there is fitness advantage for those rapid stress response genes got replicated first, because they can facilitate the replication of the rest of genome. Similar to bacterial evolution to present genomic order, in the somatic evolution of cancer, genomic shuffling was also frequently observed, especially under genotoxic chemotherapy. Such re-arrangement of genome can be viewed as a journey to optimal point in the rugged fitness landscape of genomic order.

  10. Sodium interaction with ordered structures in mammalian red blood cells detected by Na-23 double quantum NMR.

    PubMed Central

    Shinar, H; Knubovets, T; Eliav, U; Navon, G

    1993-01-01

    Na-23 double and triple quantum filtered NMR spectra of intact dog and human red blood cells were measured with the pulse sequence 90 degrees-tau/2-180 degrees-tau/2-theta degrees-t1-theta degrees-t2(Acq). For theta = 90 degrees the triple quantum filtered spectra exhibited the typical multiple quantum filtered lineshape, characteristic of isotropic media, while the double quantum filtered ones presented a superposition of two signals, whose proportion depended on the creation time tau. This effect is due to the formation of both second and third rank tensors. The formation of the second rank tensor, T21 results from non-zero residual quadrupolar interaction and is related to the anisotropic motion of sodium ions. Measurements of the double quantum filtered spectra with theta = 54.7 degrees enabled the detection of the contribution of T21 exclusively. No residual quadrupolar interaction was detected for sodium in the cytoplasm, while unsealed ghosts displayed the double quantum filtered spectral pattern, similar to that of intact cells. The anisotropy of motion of the sodium at the plasma membrane of mammalian erythrocytes depended on the integrity of the cytoskeleton network. Theoretical analysis of the double quantum filtered spectra gave a value of residual quadrupolar splitting of approximately 20 Hz for intact unsealed ghosts. The data presented prove that double quantum filtering is a sensitive technique for detection of motional anisotropies in biological systems. Images FIGURE 5 PMID:8494983

  11. Spatial processes in linear ordering.

    PubMed

    von Hecker, Ulrich; Klauer, Karl Christoph; Wolf, Lukas; Fazilat-Pour, Masoud

    2016-07-01

    Memory performance in linear order reasoning tasks (A > B, B > C, C > D, etc.) shows quicker, and more accurate responses to queries on wider (AD) than narrower (AB) pairs on a hypothetical linear mental model (A - B - C - D). While indicative of an analogue representation, research so far did not provide positive evidence for spatial processes in the construction of such models. In a series of 7 experiments we report such evidence. Participants respond quicker when the dominant element in a pair is presented on the left (or top) rather than on the right (or bottom). The left-anchoring tendency reverses in a sample with Farsi background (reading/writing from right to left). Alternative explanations and confounds are tested. A theoretical model is proposed that integrates basic assumptions about acquired reading/writing habits as a scaffold for spatial simulation, and primacy/dominance representation within such spatial simulations. (PsycINFO Database Record PMID:26641448

  12. Recent advances in ordered intermetallics

    SciTech Connect

    Liu, C.T.

    1992-12-31

    This paper briefly summarizes recent advances in intermetallic research and development. Ordered intermetallics based on aluminides and silicides possess attractive properties for structural applications at elevated temperatures in hostile environments; however, brittle fracture and poor fracture resistance limit their use as engineering materials in many cases. In recent years, considerable efforts have been devoted to the study of the brittle fracture behavior of intermetallic alloys; as a result, both intrinsic and extrinsic factors governing brittle fracture have been identified. Recent advances in first-principles calculations and atomistic simulations further help us in understanding atomic bonding, dislocation configuration, and alloying effects in intermetallics. The basic understanding has led to the development of nickel, iron, and titanium aluminide alloys with improved mechanical and metallurgical properties for structural use. Industrial interest in ductile intermetallic alloys is high, and several examples of industrial involvement are mentioned.

  13. Dependency Ordering of Atomic Observables

    NASA Astrophysics Data System (ADS)

    Cīrulis, Jānis

    2015-12-01

    The notion of atomic observable was introduced by S.Gudder for effect test spaces in 1997. In this paper an observable is a σ-homomorphism from the Borel algebra on a line to some logic. Roughly, an observable on a logic is atomic, if it is completely determined by its restriction to one-element subsets of its point spectrum. In particular, every discrete observable is atomic. We study some elementary properties of such observables, and discuss a possible notion of functional dependency between them. Algebraically, a dependency is a certain preorder relation on the set of all atomic observables, which induces an order relation on the set of all maximal orthogonal subsets of the logic. Several properties, as well as characteristics in terms of the underlying logic, of these relations are stated.

  14. Ordered chlorinated monolayer silicene structures

    NASA Astrophysics Data System (ADS)

    Li, Wenbin; Sheng, Shaoxiang; Chen, Jian; Cheng, Peng; Chen, Lan; Wu, Kehui

    2016-04-01

    We report on a systematic experimental study on the chlorination of monatomic silicene layer on Ag(111) by scanning tunneling microscopy. Monolayer silicene on Ag(111) can form 4×4, (√13×√13)R ± 13.9°, and (2√3×2√3)R30° reconstructions due to their different buckling configurations. We found that at low dosage, Cl atoms attach to the upper buckled Si atoms without changing the buckling configuration of the silicene monolayer. However, at high coverage, the global buckling configuration will be significantly changed, resulting in new ordered structures. Interestingly, all monolayer silicene structures, regardless of their initial reconstructions, tend to form a local silicene 1×1 structure at the saturation coverage. The mechanism for chlorination of monolayer silicene is explained.

  15. Discourse on order vs. disorder.

    PubMed

    Annila, Arto; Baverstock, Keith

    2016-01-01

    The second law of thermodynamics is on one hand understood to account for irrevocable flow of energy from the top down, on the other hand it is seen to imply irreversible increase of disorder. This tension between the 2 stances is resolved in favor of the free energy consumption when entropy is derived from the statistical mechanics of open systems. The change in entropy is shown to map directly to the decrease in free energy without any connotation attached to disorder. Increase of disorder, just as order, is found to be merely a consequence of free energy consumption. The erroneous association of disorder with entropy stems from an unwarranted assumption that a system could undergo changes of state without concomitant dissipation, i.e., a change in energy. PMID:27574534

  16. Ordered structures and jet noise

    NASA Technical Reports Server (NTRS)

    Petersen, R. A.; Kaplan, R. E.; Laufer, J.

    1974-01-01

    A series of measurements of near field pressures and turbulent velocity fluctuations were made in a jet having a Reynolds number of about 50,000 in order to investigate more quantitatively the character and behavior of the large scale structures, and to ascertain their importance to the jet noise problem. It was found that the process of interaction between vortices can be inhibited by artificially exciting the shear layers with periodic disturbances of certain frequency. The turbulent fluctuation amplitudes measured at four diameters downstream decreased considerably. Finally, it was observed that the passage frequency of the structures decreased with x in a similar manner as the frequency corresponding to the maximum intensity radiation emanating from the same value of x.

  17. Discourse on order vs. disorder

    PubMed Central

    Annila, Arto; Baverstock, Keith

    2016-01-01

    ABSTRACT The second law of thermodynamics is on one hand understood to account for irrevocable flow of energy from the top down, on the other hand it is seen to imply irreversible increase of disorder. This tension between the 2 stances is resolved in favor of the free energy consumption when entropy is derived from the statistical mechanics of open systems. The change in entropy is shown to map directly to the decrease in free energy without any connotation attached to disorder. Increase of disorder, just as order, is found to be merely a consequence of free energy consumption. The erroneous association of disorder with entropy stems from an unwarranted assumption that a system could undergo changes of state without concomitant dissipation, i.e., a change in energy. PMID:27574534

  18. Deriving Laws from Ordering Relations

    NASA Technical Reports Server (NTRS)

    Knuth, Kevin H.

    2003-01-01

    It took much effort in the early days of non-Euclidean geometry to break away from the mindset that all spaces are flat and that two distinct parallel lines do not cross. Up to that point, all that was known was Euclidean geometry, and it was difficult to imagine anything else. We have suffered a similar handicap brought on by the enormous relevance of Boolean algebra to the problems of our age-logic and set theory. Previously, I demonstrated that the algebra of questions is not Boolean, but rather is described by the free distributive algebra. To get to this stage took much effort, as many obstacles-most self-placed-had to be overcome. As Boolean algebras were all I had ever known, it was almost impossible for me to imagine working with an algebra where elements do not have complements. With this realization, it became very clear that the sum and product rules of probability theory at the most basic level had absolutely nothing to do with the Boolean algebra of logical statements. Instead, a measure of degree of inclusion can be invented for many different partially ordered sets, and the sum and product rules fall out of the associativity and distributivity of the algebra. To reinforce this very important idea, this paper will go over how these constructions are made, while focusing on the underlying assumptions. I will derive the sum and product rules for a distributive lattice in general and demonstrate how this leads to probability theory on the Boolean lattice and is related to the calculus of quantum mechanical amplitudes on the partially ordered set of experimental setups. I will also discuss the rules that can be derived from modular lattices and their relevance to the cross-ratio of projective geometry.

  19. Logistic equation of arbitrary order

    NASA Astrophysics Data System (ADS)

    Grabowski, Franciszek

    2010-08-01

    The paper is concerned with the new logistic equation of arbitrary order which describes the performance of complex executive systems X vs. number of tasks N, operating at limited resources K, at non-extensive, heterogeneous self-organization processes characterized by parameter f. In contrast to the classical logistic equation which exclusively relates to the special case of sub-extensive homogeneous self-organization processes at f=1, the proposed model concerns both homogeneous and heterogeneous processes in sub-extensive and super-extensive areas. The parameter of arbitrary order f, where -∞

  20. Fourth order spatial derivative gravity

    NASA Astrophysics Data System (ADS)

    Bemfica, F. S.; Gomes, M.

    2011-10-01

    In this work, we study a modified theory of gravity that contains up to fourth order spatial derivatives as a model for the Hořava-Lifshitz gravity. The propagator is evaluated and, as a result, one extra pole is obtained, corresponding to a spin-2 nonrelativistic massless particle, an extra term which jeopardizes renormalizability, besides the unexpected general relativity unmodified propagator. Then unitarity is proved at the tree level, where the general relativity pole has been shown to have no dynamics, remaining only the 2 degrees of freedom of the new pole. Next, the nonrelativistic effective potential is determined from a scattering process of two identical massive gravitationally interacting bosons. In this limit, Newton’s potential is obtained, together with a Darwin-like term that comes from the extra nonpole term in the propagator. Regarding renormalizability, this extra term may be harmful by power counting, but it can be eliminated by adjusting the free parameters of the model. This adjustment is in accord with the detailed balance condition suggested in the literature and shows that the way in which extra spatial derivative terms are added is of fundamental importance.

  1. Higher order turbulence closure models

    NASA Technical Reports Server (NTRS)

    Amano, Ryoichi S.; Chai, John C.; Chen, Jau-Der

    1988-01-01

    Theoretical models are developed and numerical studies conducted on various types of flows including both elliptic and parabolic. The purpose of this study is to find better higher order closure models for the computations of complex flows. This report summarizes three new achievements: (1) completion of the Reynolds-stress closure by developing a new pressure-strain correlation; (2) development of a parabolic code to compute jets and wakes; and, (3) application to a flow through a 180 deg turnaround duct by adopting a boundary fitted coordinate system. In the above mentioned models near-wall models are developed for pressure-strain correlation and third-moment, and incorporated into the transport equations. This addition improved the results considerably and is recommended for future computations. A new parabolic code to solve shear flows without coordinate tranformations is developed and incorporated in this study. This code uses the structure of the finite volume method to solve the governing equations implicitly. The code was validated with the experimental results available in the literature.

  2. Dislocation sources in ordered intermetallics

    SciTech Connect

    Yoo, M.H.; Appel, F.; Wagner, R.; Mecking, H.

    1996-09-01

    An overview on the current understanding of dislocation sources and multiplication mechanisms is made for ordered intermetallic alloys of the L1{sub 2}, B2, and D0{sub 19} structures. In L1{sub 2} alloys, a large disparity of edge/screw segments in their relative mobility reduces the efficiency of a Frank-Read Type multiplication mechanism. In Fe-40%Al of the B2 structure, a variety of dislocation sources are available for <111> slip, including ones resulting from condensation of thermal vacancies. In NiAl with the relatively high APB energy, <100> dislocations may result from the dislocation decomposition reactions, the prismatic punching out from inclusion particles, and/or steps and coated layers of the surface. Internal interfaces often provide sites for dislocation multiplication, e.g., grain boundaries, sub-boundaries in Ni{sub 3}Ga, NiAl and Ti{sub 3}Al, and antiphase domain boundaries in Ti{sub 3}Al. As for the crack tip as a dislocation source, extended SISFs trailed by super-Shockley partials emanating form the cracks in Ni{sub 3}Al and Co{sub 3}Ti are discussed in view of a possible toughening mechanism.

  3. Fourth order spatial derivative gravity

    SciTech Connect

    Bemfica, F. S.; Gomes, M.

    2011-10-15

    In this work, we study a modified theory of gravity that contains up to fourth order spatial derivatives as a model for the Horava-Lifshitz gravity. The propagator is evaluated and, as a result, one extra pole is obtained, corresponding to a spin-2 nonrelativistic massless particle, an extra term which jeopardizes renormalizability, besides the unexpected general relativity unmodified propagator. Then unitarity is proved at the tree level, where the general relativity pole has been shown to have no dynamics, remaining only the 2 degrees of freedom of the new pole. Next, the nonrelativistic effective potential is determined from a scattering process of two identical massive gravitationally interacting bosons. In this limit, Newton's potential is obtained, together with a Darwin-like term that comes from the extra nonpole term in the propagator. Regarding renormalizability, this extra term may be harmful by power counting, but it can be eliminated by adjusting the free parameters of the model. This adjustment is in accord with the detailed balance condition suggested in the literature and shows that the way in which extra spatial derivative terms are added is of fundamental importance.

  4. Liquid crystalline order in mucus

    NASA Technical Reports Server (NTRS)

    Viney, C.; Huber, A. E.; Verdugo, P.

    1993-01-01

    Mucus plays an exceptionally wide range of important biological roles. It operates as a protective, exchange, and transport medium in the digestive, respiratory, and reproductive systems of humans and other vertebrates. Mucus is a polymer hydrogel. It is secreted as discrete packages (secretory granules) by specialized secretory cells. Mucus hydrogel is stored in a condensed state inside the secretory granules. Depending upon the architecture of their constituent macromolecules and on the composition of the solvent, polymer gels can form liquid crystalline microstructures, with orientational order being exhibited over optically resolvable distances. Individual mucin molecules consist of alternating rigid segments (heavily glycosylated; hydrophilic) and flexible segments (nonglycosylated; hydrophobic). Polymer molecules consisting of rigid units linked by flexible spacers are frequently associated with liquid crystalline behavior, which again raises the possibility that mucus could form anisotropic fluid phases. Suggestions that mucins may be self-associating in dilute solution have previously been challenged on the basis of sedimentation-equilibrium studies performed on mucus in which potential sites of association were competitively blocked with inhibitors. However, the formation of stable liquid crystalline phases does not depend on the existence of inter- or intramolecular associations; these phases can form on the basis of steric considerations alone.

  5. Interior order expands minerals management

    NASA Astrophysics Data System (ADS)

    Richman, Barbara T.

    In a surprise move on May 10, Secretary of the Interior James G. Watt ordered the consolidation of all leasing and resource management functions for the outer continental shelf (OCS) into the Minerals Management Service (MMS). Among those programs shifted to MMS are ‘all functions in direct support of the OCS program’ in the Geologic Division and in the Office of the Assistant Director for Resource Programs of the U.S. Geological Survey (USGS), including oil and gas resources, energy-related hazards, and marine geology investigations. It is unclear whether research associated with the OCS leasing functions will be considered ‘direct support’ and what will happen to the research if it is so considered.Also to be shuttled to MMS are the oil-spill trajectory functions of the Office of Earth Sciences Applications and all the functions of the Office of Policy Analysis relating to the OCS that had been transferred from the Department of Energy as a result of the Interior and Related Agencies Appropriations Act.

  6. Deriving Laws from Ordering Relations

    NASA Technical Reports Server (NTRS)

    Knuth, Kevin H.

    2004-01-01

    The effect of Richard T. Cox's contribution to probability theory was to generalize Boolean implication among logical statements to degrees of implication, which are manipulated using rules derived from consistency with Boolean algebra. These rules are known as the sum rule, the product rule and Bayes Theorem, and the measure resulting from this generalization is probability. In this paper, I will describe how Cox s technique can be further generalized to include other algebras and hence other problems in science and mathematics. The result is a methodology that can be used to generalize an algebra to a calculus by relying on consistency with order theory to derive the laws of the calculus. My goals are to clear up the mysteries as to why the same basic structure found in probability theory appears in other contexts, to better understand the foundations of probability theory, and to extend these ideas to other areas by developing new mathematics and new physics. The relevance of this methodology will be demonstrated using examples from probability theory, number theory, geometry, information theory, and quantum mechanics.

  7. Advanced ordered intermetallic alloy deployment

    SciTech Connect

    Liu, C.T.; Maziasz, P.J.; Easton, D.S.

    1997-04-01

    The need for high-strength, high-temperature, and light-weight materials for structural applications has generated a great deal of interest in ordered intermetallic alloys, particularly in {gamma}-based titanium aluminides {gamma}-based TiAl alloys offer an attractive mix of low density ({approximately}4g/cm{sup 3}), good creep resistance, and high-temperature strength and oxidation resistance. For rotating or high-speed components. TiAl also has a high damping coefficient which minimizes vibrations and noise. These alloys generally contain two phases. {alpha}{sub 2} (DO{sub 19} structure) and {gamma} (L 1{sub 0}), at temperatures below 1120{degrees}C, the euticoid temperature. The mechanical properties of TiAl-based alloys are sensitive to both alloy compositions and microstructure. Depending on heat-treatment and thermomechanical processing, microstructures with near equiaxed {gamma}, a duplex structure (a mix of the {gamma} and {alpha}{sub 2} phases) can be developed in TiAl alloys containing 45 to 50 at. % Al. The major concern for structural use of TiAl alloys is their low ductility and poor fracture resistance at ambient temperatures. The purpose of this project is to improve the fracture toughness of TiAl-based alloys by controlling alloy composition, microstructure and thermomechanical treatment. This work is expected to lead to the development of TiAl alloys with significantly improved fracture toughness and tensile ductility for structural use.

  8. Scaling exponents for ordered maxima

    SciTech Connect

    Ben-Naim, E.; Krapivsky, P. L.; Lemons, N. W.

    2015-12-22

    We study extreme value statistics of multiple sequences of random variables. For each sequence with N variables, independently drawn from the same distribution, the running maximum is defined as the largest variable to date. We compare the running maxima of m independent sequences and investigate the probability SN that the maxima are perfectly ordered, that is, the running maximum of the first sequence is always larger than that of the second sequence, which is always larger than the running maximum of the third sequence, and so on. The probability SN is universal: it does not depend on the distribution from which the random variables are drawn. For two sequences, SN~N–1/2, and in general, the decay is algebraic, SN~N–σm, for large N. We analytically obtain the exponent σ3≅1.302931 as root of a transcendental equation. Moreover, the exponents σm grow with m, and we show that σm~m for large m.

  9. Scaling exponents for ordered maxima

    DOE PAGESBeta

    Ben-Naim, E.; Krapivsky, P. L.; Lemons, N. W.

    2015-12-22

    We study extreme value statistics of multiple sequences of random variables. For each sequence with N variables, independently drawn from the same distribution, the running maximum is defined as the largest variable to date. We compare the running maxima of m independent sequences and investigate the probability SN that the maxima are perfectly ordered, that is, the running maximum of the first sequence is always larger than that of the second sequence, which is always larger than the running maximum of the third sequence, and so on. The probability SN is universal: it does not depend on the distribution frommore » which the random variables are drawn. For two sequences, SN~N–1/2, and in general, the decay is algebraic, SN~N–σm, for large N. We analytically obtain the exponent σ3≅1.302931 as root of a transcendental equation. Moreover, the exponents σm grow with m, and we show that σm~m for large m.« less

  10. 10 CFR 820.42 - Final order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Final order. 820.42 Section 820.42 Energy DEPARTMENT OF ENERGY PROCEDURAL RULES FOR DOE NUCLEAR ACTIVITIES Compliance Orders § 820.42 Final order. A Compliance Order is a Final Order that constitutes a DOE Nuclear Safety Requirement that is effective...

  11. 10 CFR 1013.24 - Protective order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Protective order. 1013.24 Section 1013.24 Energy... order. (a) A party or a prospective witness or deponent may file a motion for a protective order with... availability or disclosure of evidence. (b) In issuing a protective order, the ALJ may make any order...

  12. 7 CFR 966.110 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Order. 966.110 Section 966.110 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE TOMATOES GROWN IN FLORIDA Rules and Regulations Definitions § 966.110 Order. Order means Order No. 966 (§§ 966.1 to 966.92) regulating...

  13. 7 CFR 966.110 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Order. 966.110 Section 966.110 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE TOMATOES GROWN IN FLORIDA Rules and Regulations Definitions § 966.110 Order. Order means Order No. 966 (§§ 966.1 to 966.92) regulating...

  14. 7 CFR 966.110 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Order. 966.110 Section 966.110 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE TOMATOES GROWN IN FLORIDA Rules and Regulations Definitions § 966.110 Order. Order means Order No. 966 (§§ 966.1 to 966.92) regulating...

  15. 7 CFR 927.102 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Order. 927.102 Section 927.102 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PEARS GROWN IN OREGON AND WASHINGTON Rules and Regulations Definitions § 927.102 Order. Order means Marketing Order No. 927, as amended (§§...

  16. 7 CFR 966.110 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Order. 966.110 Section 966.110 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE TOMATOES GROWN IN FLORIDA Rules and Regulations Definitions § 966.110 Order. Order means Order No. 966 (§§ 966.1 to 966.92) regulating...

  17. 7 CFR 948.100 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Order. 948.100 Section 948.100 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Rules and Regulations General § 948.100 Order. Order means §§ 948.1 to 948.92 (Order No. 948 as amended) regulating...

  18. 7 CFR 946.100 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Order. 946.100 Section 946.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Rules and Regulations Definitions § 946.100 Order. Order means Order No. 946 (§§ 946.1 to 946.78), as...

  19. 7 CFR 946.100 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Order. 946.100 Section 946.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Rules and Regulations Definitions § 946.100 Order. Order means Order No. 946 (§§ 946.1 to 946.78), as...

  20. 7 CFR 948.100 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Order. 948.100 Section 948.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Rules and Regulations General § 948.100 Order. Order means §§ 948.1 to 948.92 (Order No. 948 as amended) regulating...

  1. 7 CFR 948.100 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Order. 948.100 Section 948.100 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Rules and Regulations General § 948.100 Order. Order means §§ 948.1 to 948.92 (Order No. 948 as amended) regulating...

  2. 7 CFR 966.110 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Order. 966.110 Section 966.110 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE TOMATOES GROWN IN FLORIDA Rules and Regulations Definitions § 966.110 Order. Order means Order No. 966 (§§ 966.1 to 966.92) regulating...

  3. 7 CFR 946.100 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Order. 946.100 Section 946.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Rules and Regulations Definitions § 946.100 Order. Order means Order No. 946 (§§ 946.1 to 946.78), as...

  4. 7 CFR 959.100 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Order. 959.100 Section 959.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ONIONS GROWN IN SOUTH TEXAS Rules and Regulations General § 959.100 Order. Order means Order No. 959 (§§ 959.1 to 959.92; 26 FR 704) regulating...

  5. 7 CFR 927.102 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Order. 927.102 Section 927.102 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE PEARS GROWN IN OREGON AND WASHINGTON Rules and Regulations Definitions § 927.102 Order. Order means Marketing Order No. 927, as amended (§§...

  6. 10 CFR 820.42 - Final order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Final order. 820.42 Section 820.42 Energy DEPARTMENT OF ENERGY PROCEDURAL RULES FOR DOE NUCLEAR ACTIVITIES Compliance Orders § 820.42 Final order. A Compliance Order is a Final Order that constitutes a DOE Nuclear Safety Requirement that is effective...

  7. 7 CFR 959.100 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Order. 959.100 Section 959.100 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE ONIONS GROWN IN SOUTH TEXAS Rules and Regulations General § 959.100 Order. Order means Order No. 959 (§§ 959.1 to 959.92; 26 FR 704) regulating...

  8. 7 CFR 959.100 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Order. 959.100 Section 959.100 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE ONIONS GROWN IN SOUTH TEXAS Rules and Regulations General § 959.100 Order. Order means Order No. 959 (§§ 959.1 to 959.92; 26 FR 704) regulating...

  9. 7 CFR 959.100 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Order. 959.100 Section 959.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ONIONS GROWN IN SOUTH TEXAS Rules and Regulations General § 959.100 Order. Order means Order No. 959 (§§ 959.1 to 959.92; 26 FR 704) regulating...

  10. 7 CFR 927.102 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Order. 927.102 Section 927.102 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE PEARS GROWN IN OREGON AND WASHINGTON Rules and Regulations Definitions § 927.102 Order. Order means Marketing Order No. 927, as amended (§§...

  11. 7 CFR 927.102 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Order. 927.102 Section 927.102 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE PEARS GROWN IN OREGON AND WASHINGTON Rules and Regulations Definitions § 927.102 Order. Order means Marketing Order No. 927, as amended (§§...

  12. 7 CFR 948.100 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Order. 948.100 Section 948.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Rules and Regulations General § 948.100 Order. Order means §§ 948.1 to 948.92 (Order No. 948 as amended) regulating...

  13. 7 CFR 946.100 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 8 2014-01-01 2014-01-01 false Order. 946.100 Section 946.100 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Rules and Regulations Definitions § 946.100 Order. Order means Order No. 946 (§§ 946.1 to 946.78), as...

  14. 7 CFR 959.100 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 8 2011-01-01 2011-01-01 false Order. 959.100 Section 959.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE ONIONS GROWN IN SOUTH TEXAS Rules and Regulations General § 959.100 Order. Order means Order No. 959 (§§ 959.1 to 959.92; 26 FR 704) regulating...

  15. 7 CFR 948.100 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 8 2012-01-01 2012-01-01 false Order. 948.100 Section 948.100 Agriculture Regulations... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Rules and Regulations General § 948.100 Order. Order means §§ 948.1 to 948.92 (Order No. 948 as amended) regulating...

  16. 7 CFR 946.100 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 8 2013-01-01 2013-01-01 false Order. 946.100 Section 946.100 Agriculture Regulations... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN WASHINGTON Rules and Regulations Definitions § 946.100 Order. Order means Order No. 946 (§§ 946.1 to 946.78), as...

  17. 10 CFR 590.402 - Conditional orders.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... WITH RESPECT TO THE IMPORT AND EXPORT OF NATURAL GAS Opinions and Orders § 590.402 Conditional orders... issuance of a final opinion and order. The conditional order shall include the basis for not issuing a final opinion and order at that time and a statement of findings and conclusions. The findings...

  18. 10 CFR 590.402 - Conditional orders.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... WITH RESPECT TO THE IMPORT AND EXPORT OF NATURAL GAS Opinions and Orders § 590.402 Conditional orders... issuance of a final opinion and order. The conditional order shall include the basis for not issuing a final opinion and order at that time and a statement of findings and conclusions. The findings...

  19. 2H nuclear magnetic resonance order parameter profiles suggest a change of molecular shape for phosphatidylcholines containing a polyunsaturated acyl chain.

    PubMed Central

    Holte, L. L.; Peter, S. A.; Sinnwell, T. M.; Gawrisch, K.

    1995-01-01

    Solid-state 2H nuclear magnetic resonance spectroscopy was used to determine the orientational order parameter profiles for a series of phosphatidylcholines with perdeuterated stearic acid, 18:0d35, in position sn-1 and 18:1 omega 9, 18:2 omega 6, 18:3 omega 3, 20:4 omega 6, 20:5 omega 3, or 22:6 omega 3 in position sn-2. The main phase transition temperatures were derived from a first moment analysis, and order parameter profiles of sn-1 chains were calculated from dePaked nuclear magnetic resonance powder patterns. Comparison of the profiles at 37 degrees C showed that unsaturation causes an inhomogenous disordering along the sn-1 chain. Increasing sn-2 chain unsaturation from one to six double bonds resulted in a 1.6-kHz decrease in quadrupolar splittings of the sn-1 chain in the upper half of the chain (or plateau region) and maximum splitting difference of 4.4 kHz at methylene carbon 14. The change in chain order corresponds to a decrease in the 18:0 chain length of 0.4 +/- 0.2 A with 18:2 omega 6 versus 18:1 omega 9 in position sn-2. Fatty acids containing three or more double bonds in sn-2 showed a decrease in sn-1 chain length of 0.7 +/- 0.2 A compared with 18:1 omega 9. The chain length of all lipids decreased with increasing temperature. Highly unsaturated phosphatidylcholines (three or more double bonds in sn-2) had shorter sn-1 chains, but the chain length was somewhat less sensitive to temperature. The profiles reveal that the sn-1 chain exhibits a selective increase in motional freedom in a region located toward the bottom half of the chain as sn-2 unsaturation is increased. This corresponds to an area increase around carbon atom number 14 that is three to four times greater than the increase for the top part of the chain. A similar asymmetric decrease in order, largest toward the methyl end of the chain, was observed when 1 -palmitoyl-2-oleoylphosphatidylethanolamine goes from a lamellar to an inverse hexagonal (H,,) phase. This is consistent with a

  20. 7 CFR 1219.17 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order Definitions § 1219.17...