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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 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.

  5. 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.

  6. Magnetic field induced dynamical chaos.

    PubMed

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

    2013-12-01

    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. PMID:24387560

  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 shape recovery by reverse phase transformation.

    PubMed

    Kainuma, R; Imano, Y; Ito, W; Sutou, Y; Morito, H; Okamoto, S; Kitakami, O; Oikawa, K; Fujita, A; Kanomata, T; Ishida, K

    2006-02-23

    Large magnetic-field-induced strains have been observed in Heusler alloys with a body-centred cubic ordered structure and have been explained by the rearrangement of martensite structural variants due to an external magnetic field. These materials have attracted considerable attention as potential magnetic actuator materials. Here we report the magnetic-field-induced shape recovery of a compressively deformed NiCoMnIn alloy. Stresses of over 100 MPa are generated in the material on the application of a magnetic field of 70 kOe; such stress levels are approximately 50 times larger than that generated in a previous ferromagnetic shape-memory alloy. We observed 3 per cent deformation and almost full recovery of the original shape of the alloy. We attribute this deformation behaviour to a reverse transformation from the antiferromagnetic (or paramagnetic) martensitic to the ferromagnetic parent phase at 298 K in the Ni45Co5Mn36.7In13.3 single crystal. PMID:16495995

  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. 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.

  11. Tetrahedratic mesophases, chiral order, and helical domains induced by quadrupolar and octupolar interactions

    NASA Astrophysics Data System (ADS)

    Trojanowski, Karol; Pająk, Grzegorz; Longa, Lech; Wydro, Thomas

    2012-07-01

    We present an exhaustive account of phases and phase transitions that can be stabilized in the recently introduced generalized Lebwohl-Lasher model with quadrupolar and octupolar microscopic interactions [L. Longa, G. Pająk, and T. Wydro, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.79.040701 79, 040701(R) (2009)]. A complete mean-field analysis of the model, along with Monte Carlo simulations allows us to identify four distinct classes of the phase diagrams with a number of multicritical points where, in addition to the standard uniaxial and biaxial nematic phases, the other nematic like phases are stabilized. These involve, among the others, tetrahedratic (T), nematic tetrahedratic (NT), and chiral nematic tetrahedratic (NT*) phases of global Td, D2d, and D2 symmetry, respectively. Molecular order parameters and correlation functions in these phases are determined. We conclude with generalizations of the model that give a simple molecular interpretation of macroscopic regions with opposite optical activity (ambidextrous chirality), observed, e.g., in bent-core systems. An estimate of the helical pitch in the NT* phase is also given.

  12. 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.

  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. Optical gyrotropy in quadrupolar Kondo systems

    NASA Astrophysics Data System (ADS)

    Lee, SungBin; Paramekanti, Arun; Kim, Yong Baek

    2015-01-01

    Recent experiments point to a variety of intermetallic systems which exhibit exotic quadrupolar orders driven by the Kondo coupling between conduction electrons and localized quadrupolar degrees of freedom. Using a Luttinger k .p Hamiltonian for the conduction electrons, we study the impact of such quadrupolar order on their energies and wave functions. We discover that such quadrupolar orders can induce a nontrivial Berry curvature for the conduction electron bands, leading to a nonvanishing optical gyrotropic effect. We estimate the magnitude of the gyrotropic response in a candidate quadrupolar material, PrPb3, and discuss the resulting Faraday rotation in thin films.

  15. Nematic ordering of suspension of charged anisotropic colloids detected by multinuclear quadrupolar spectra and 1H PGSE-NMR measurements.

    PubMed

    Porion, P; Al-Mukhtar, M; Faugère, A-M; Meyer, S; Delville, A

    2003-11-01

    The structure of aqueous dispersion of charged anisotropic nano-composites (synthetic Laponite clays) have been studied by NMR and numerical simulations based on a multi-scale statistical analysis have been used to interpret the mobility of the confined water molecule diffusing within dense Laponite aqueous dispersions (29-52% w/w) prepared by uniaxial compression. Firstly, the lineshape detected by NMR quadrupolar spectroscopy of the counterions ((23)Na or (7)Li) exhibits a large residual splitting Delta nu which is the fingerprint of the macroscopic nematic ordering of the anisotropic particles. Secondly, these results are also confirmed by the anisotropy of the self-diffusion tensor of the water molecule measured by (1)H Pulsed Gradient Spin Echo NMR. This self-diffusion anisotropy increases with the suspension density. Thirdly, the multi-scale statistical analysis of the water mobility bridges the gap between the time-scale (ps) accessible by Molecular Dynamics simulations and the time-scale (micros) accessible by Brownian Dynamics, leading to macroscopic behaviour comparable with PGSE-NMR data measurements. PMID:15011007

  16. 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

  17. 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

  18. 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.

  19. Spontaneous and external magnetic field-induced magnetostriction in RCo2-based multicomponent alloys

    NASA Astrophysics Data System (ADS)

    Politova, G. A.; Chzhan, V. B.; Tereshina, I. S.; Burkhanov, G. S.; Manakov, A. A.; Alekseeva, O. A.; Filimonov, A. V.; Ilyushin, A. S.

    2015-12-01

    The spontaneous and external magnetic field-induced magnetostrictions have been studied in multicomponent Tb0.3Dy0.35Ho0.35Co2 and Tb0.8Dy0.1Gd0.1Co2 alloys whose structures are isotypical to the C15 Laves phases. The temperature dependences of the lattice parameters have been measured in the range of 110-280 K. It has been found that the crystal lattice undergoes rhombohedral distortions at temperatures lower than the temperatures of magnetic ordering in these alloys (148.5 and 243 K, respectively). The temperature (4.2-280 K) and field (0-8 T) dependences of the longitudinal and transverse magnetostrictions have been studied. The high magnetoelastic effects have been detected.

  20. 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.

  1. 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

  2. Growth of Magnetic Fields Induced by Turbulent Motions

    NASA Astrophysics Data System (ADS)

    Cho, Jungyeon; Vishniac, Ethan T.; Beresnyak, Andrey; Lazarian, A.; Ryu, Dongsu

    2009-03-01

    We present numerical simulations of driven magnetohydrodynamic (MHD) turbulence with weak/moderate imposed magnetic fields. The main goal is to clarify dynamics of magnetic field growth. We also investigate the effects of the imposed magnetic fields on the MHD turbulence, including, as a limit, the case of zero external field. Our findings are as follows. First, when we start off simulations with weak mean magnetic field only (or with small scale random field with zero imposed field), we observe that there is a stage at which magnetic energy density grows linearly with time. Runs with different numerical resolutions and/or different simulation parameters show consistent results for the growth rate at the linear stage. Second, we find that, when the strength of the external field increases, the equilibrium kinetic energy density drops by roughly the product of the rms velocity and the strength of the external field. The equilibrium magnetic energy density rises by roughly the same amount. Third, when the external magnetic field is not very strong (say, less than ~0.2 times the rms velocity when measured in the units of Alfvn speed), the turbulence at large scales remains statistically isotropic, i.e., there is no apparent global anisotropy of order B 0/v. We discuss implications of our results on astrophysical fluids.

  3. 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.

  4. 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.

  5. 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.

  6. Magnetic field induced quantum phase transitions in the two-impurity Anderson model

    SciTech Connect

    Zhu, Lujun; Zhu, Jian - Xin

    2010-11-17

    In the two-impurity Anderson model, the inter-impurity spin exchange interaction favors a spin singlet state between two impurities leading to the localization of quasiparticles. We show that a local uniform magnetic field can delocalize the quasiparticies to restore the Kondo resonance. This transition is found to be continuous, accompanied by not only the divergence of the staggered (anti ferromagnetic) susceptibility, but also the divergence of the uniform spin susceptibility. This implies that the magnetic field induced quantum phase transitions in Kondo systems are in favor of the local critical type.

  7. Magnetic-field induced bistability in a quasi-one-dimensional semiconductor microcavity

    NASA Astrophysics Data System (ADS)

    Zhang, Chuanyi; Zhang, Weifeng

    2015-09-01

    We theoretically study the magnetic-field induced bistability in a quasi-one-dimensional semiconductor microcavity. A critical magnetic field is obtained, and the bistability appears if a magnetic field is greater than the critical value. For a positive energy detuning of the pump from the bare exciton polaritons, one bistability loop first emerges, then it divides into two loops, and finally one of them vanishes with the increasing magnetic field. This phenomenon originates from the magnetic-field modulated interactions for opposite spins. In the variational process, there are two important effects: one is a logic gate with a small variation of the excitation laser, and the other is a spin texture like skyrmion and this texture is periodic if the energy detuning varies periodically in real space, which is useful for designing the spin-dependent optoelectronic devices.

  8. 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.

  9. Magnetic-field-induced transformation in FeMnGa alloys

    SciTech Connect

    Zhu, W.; Liu, E. K.; Feng, L.; Tang, X. D.; Chen, J. L.; Wu, G. H.; Liu, H. Y.; Meng, F. B.; Luo, H. Z.

    2009-11-30

    A kind of ferromagnetic shape memory alloy with off-stoichiometric composition of Heusler alloy Fe{sub 2}MnGa has been synthesized. By optimizing composition, the martensitic transformation has been modified to occur at about 163 K accompanying spontaneous magnetization, which enables a magnetic field-induced structural transition from a paramagnetic parent phase to a ferromagnetic martensite with high magnetization of 93.8 emu/g. The material performs a quite large lattice distortion through the transformation, (c-a)/c=33.5%, causing a shape memory strain upto 3.6%. Such large lattice distortions strongly influence the electron structures, and thus some special physical behavior related to the transport and conductive properties is investigated.

  10. 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.

  11. 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

  12. Ab initio study of the enantio-selective magnetic-field-induced second harmonic generation in chiral molecules.

    PubMed

    Rizzo, Antonio; Rikken, G L J A; Mathevet, R

    2016-01-21

    We present a systematic ab initio study of enantio-selective magnetic-field-induced second harmonic generation (MFISHG) on a set of chiral systems ((l)-alanine, (l)-arginine and (l)-cysteine; 3,4-dehydro-(l)-proline; (S)-α-phellandrene; (R,S)- and (S,S)-cystine disulphide; N-(4-nitrophenyl)-(S)-prolinol, N-(4-(2-nitrovinyl)-phenyl)-(S)-prolinol, N-(4-tricyanovinyl-phenyl)-(S)-prolinol, (R)-BINOL, (S)-BINAM and 6-(M)-helicene). The needed electronic frequency dependent cubic response calculations are performed within a density functional theory (DFT) approach. A study of the dependence of the property on the choice of electron correlation, on one-electron basis set extension and on the choice of magnetic gauge origin is carried out on a prototype system (twisted oxygen peroxide). The magnetic gauge dependence analysis is extended also to the molecules of the set. An attempt to analyze the structure-property relationships is also made, based on the results obtained for biphenyl (in a frozen twisted conformation), for prolinol and for some of their derivatives. The strength of the effect is discussed, in order to establish its measurability with a proposed experimental setup. PMID:26682613

  13. 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.

  14. 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

  15. 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.

  16. Nanoparticle impacts reveal magnetic field induced agglomeration and reduced dissolution rates.

    PubMed

    Tschulik, Kristina; Compton, Richard G

    2014-07-21

    Superparamagnetic nanoparticles (NPs) are used in a variety of magnetic field-assisted chemical and medical applications, yet little of their fate during magnetic field interrogation is known. Here, fundamental and new insights in this are gained by cathodic particle coulometry. This methodology is used to study individual Fe3O4 NPs in the presence and absence of a magnetic field. It is first noticed that no major NP agglomeration occurs in the absence of a magnetic field even in a suspension of high ionic strength. In contrast, a significant magnetic field-induced agglomeration of NPs is observed in a magnetic field. A second new finding is that the dissolution of Fe3O4 NPs is strongly inhibited in a magnetic field. This is explained as a result of the magnetic field gradient force trapping the released Fe(2+) ions near the surface of a magnetized Fe3O4 NP and thus hindering the mass-transport controlled NP dissolution. Consequently, fundamental magnetic field effects are measured and quantified on both the single NP scale and in suspension and two novel effects are discovered. PMID:24898763

  17. Magnetic-field-induced electronic phase transitions in semimetals in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Shimamoto, Y.; Miura, N.; Nojiri, H.

    1998-12-01

    We report an experimental study of the magnetic-field-induced electronic phase transitions in semimetals (graphite and Bi) in pulsed high magnetic fields up to several hundred teslas. Far-infrared and millimetre-wave spectroscopies were employed to investigate the electric conductivity and the optical transitions between the Landau levels. In graphite a phase transition was observed in the mm-wave transmission through a specially designed strip-line system with a sample on one of the walls. Evidence of a density-wave phase transition was found in the infrared transmission at a transition field of about 30-40 T. Cyclotron resonance in very high field revealed that the n = 0 spin-up level is depopulated above a field of B = 54 T, while the n = 0 spin-down level persists under the Fermi level at least up to 200 T. In Bi, anomalous structures were observed in the strip-line mm-wave transmission spectra as well as the infrared transmission spectra, indicating a semimetal-to-semiconductor transition at around 85 T.

  18. 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

  19. Microwave complex permeability of Fe3O4 nanoflake composites with and without magnetic field-induced rotational orientation

    NASA Astrophysics Data System (ADS)

    Liu, Xianguo; Wing Or, Siu; Ming Leung, Chung; Ho, S. L.

    2013-05-01

    Magnetite (Fe3O4) nanoflakes with widths of 100-200 nm and thicknesses of 10-80 nm were prepared by a hydrothermal synthesis method. Fe3O4 nanoflake composites with and without magnetic field-induced rotational orientation of flake planes of Fe3O4 nanoflakes in paraffin binder were fabricated using 35 wt. % Fe3O4 nanoflakes. The rotationally oriented composite showed higher permeability and resonance frequency than the nonoriented one, and its value of (?0-1)fr reached 214.8 GHz and exceeded the Snoek's limit. Considering a uniform and a random distribution of flake planes of Fe3O4 nanoflakes in the oriented and nonoriented composites, respectively, the complex permeability of both composites was calculated using the Landau-Lifshitz-Gilbert equation and the Bruggeman's effective medium theory in the 2-18 GHz microwave frequency range.

  20. Tunable fringe magnetic fields induced by converse magnetoelectric coupling in a FeGa/PMN-PT multiferroic heterostructure

    NASA Astrophysics Data System (ADS)

    Fitchorov, Trifon; Chen, Yajie; Hu, Bolin; Gillette, Scott M.; Geiler, Anton; Vittoria, Carmine; Harris, Vincent G.

    2011-12-01

    The fringe magnetic field, induced by magnetoelectric coupling in a bilayer Fe-Ga/Pb(Mg1/3Nb2/3)O3_PbTiO3 (PMN-PT) multifunctional composite, was investigated. The induced external field is characterized as having a butterfly hysteresis loop when tuned by an applied electric field. A tuning coefficient of the electrically induced fringe magnetic field is derived from the piezoelectric and magnetostrictive properties of the composite. A measured maximum tuning coefficient, 4.5 Oe/(kV cm-1), is found to agree well with theoretical prediction. This work establishes a foundation in the design of transducers based on the magnetoelectric effect.

  1. Magnetic-field-induced crossover from flux-flow to Josephson-junction behavior in a highly transparent weak link

    NASA Astrophysics Data System (ADS)

    Horide, T.; Matsumoto, K.; Ichinose, A.; Mukaida, M.; Yoshida, Y.; Horii, S.

    2007-01-01

    Magnetic-field-induced Josephson-junction (JJ) behavior in a highly transparent weak link was observed at the 5° tilt low angle grain boundary (LAGB) in a YBa2Cu3O7-δ film. The magnetic field dependence of current density-voltage curves showed that Abrikosov Josephson (AJ) vortices exist in the LAGB. Both JJ and flux-flow (FF) behaviors were observed in a single LAGB depending on the temperature and magnetic field. The crossover from FF to JJ arose from the spread of the phase variation along the junction when the AJ vortex cores overlapped at B*=ϕ0/(4.4l)2 , where l is the characteristic length of AJ vortex.

  2. 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.

  3. Four-component Hartree-Fock calculations of magnetic-field induced circular birefringence--Faraday effect--in noble gases and dihalogens.

    PubMed

    Ekström, Ulf; Norman, Patrick; Rizzo, Antonio

    2005-02-15

    The effects of relativity on the magnetic-field induced circular birefringence, or Faraday effect, in He, Ne, Ar, Xe, Rn, F2, Cl2, Br2, and I2 have been determined at the four-component Hartree-Fock level of theory. A measure of the birefringence is given by the Verdet constant, which is a third-order molecular property and thus relates to quadratic response functions. A fully analytical nonlinear polarization propagator approach is employed. The results are gauge invariant as a consequence of the spatial symmetries in the molecular systems. The calculations include electronic as well as vibrational contributions to the property. Comparison with experiment is made for He, Ne, Ar, Xe, and Cl2, and, apart from neon, the theoretical values of the Verdet constant are within 10% of the experimental ones. The inclusion of nonrelativistically spin-forbidden excitations in the propagator parametrization has significant effects on the dispersion in general, but such effects are in the general case largely explained by the use of a resonant-divergent propagator theory. In the present work we do, however, observe noticeable relativistic corrections to the Verdet constant in the off-resonant regions for systems with light elements (F2 and Cl2), and nonrelativistic results for the Verdet constant of Br2 are in error by 25% in the low-frequency region. PMID:15743246

  4. Vacuum Field Ellipticity Dependence on Radius in Quadrupolar Mirror Machines

    NASA Astrophysics Data System (ADS)

    Hagnestål, A.; Ågren, O.

    2012-10-01

    The vacuum field flux tube ellipticity dependence on radius for quadrupolar mirror machines has been investigated. A third order expression in the paraxial approximation has been derived for the vacuum field ellipticity. The dependence of ellipticity on midplane radius has been examined in the SFLM Hybrid and the outermost plasma flux tube is 3.5 cm wider than predicted by the first order paraxial approximation, which is within boundaries set by the first wall. The third order approximation has a high accuracy for the ellipticity for long-thin mirrors such as the SFLM Hybrid, and even the first order approximation that is independent of radius is sufficient in many applications. The ellipticity dependence on midplane radius for mirrors with more strongly localized quadrupolar fields than the SFLM Hybrid is also shown to be minor.

  5. 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

  6. 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

  7. MnAs: magnetic-field-induced structural phase transformation and associated magnetoresistance

    NASA Astrophysics Data System (ADS)

    Mira, Jorge; Rivadulla, Francisco; Rivas, Jose; Fondado, Alfonso; Caciuffo, Roberto G. M. C.; Carsughi, F.; Guidi, Tatiana; Goodenough, John B.

    2003-03-01

    MnAs, a commercially available material first studied a century ago, exhibits a first-order phase transition from a ferromagnetic, high-spin metal NiAs-type hexagonal phase to a paramagnetic, lower-spin insulator MnP-type orthorhombic phase at T_C= 313 K. We report the results of neutron diffraction experiments showing that an external magnetic field, B, stabilizes the hexagonal metallic phase above T_C. The phase transformation is reversible and constitutes the first demonstration of a bond-breking transition induced by a magnetic field. At 322 K the hexagonal structure is restored for B > 4 tesla. The field-induced phase transition is accompanied by an enhanced magnetoresistance of about 17 % at 310 K. We discuss the origig of this phenomenon, which appears to be similar to that of the colossal magnetoresistance response observed in some members of the manganese perovskite family.

  8. Magnetic-field induced singlet-triplet phase transition in quasi one-dimensional organic superconductors

    NASA Astrophysics Data System (ADS)

    Belmechri, N.; Abramovici, G.; Héritier, M.; Haddad, S.; Charfi-Kaddour, S.

    2007-11-01

    We propose a theoretical model of quasi-one-dimensional superconductors, with attractive electron-electron interactions dominant in the singlet d-wave channel and sub-dominant in the p-wave channel. We discuss, in the mean-field approximation, the effect of a magnetic field applied perpendicularly to the direction of the lowest conductivity. The lowest free energy phase corresponds to a singlet d-wave symmetry in low fields, but to a triplet symmetry in high fields. A first-order singlet-triplet phase transition is expected at moderate applied fields of a few teslas. We propose to ascribe the recent critical field and NMR experimental data, observed in superconducting (TMTSF)2ClO4 to such an effect.

  9. Zeeman effect and magnetic field induced spin-hybridization in semiconductor quantum dots

    NASA Astrophysics Data System (ADS)

    Prado, S. J.; López-Richard, V.; Alcalde, A. M.; Marques, G. E.; Hai, G. Q.

    2004-10-01

    We present a systematic theoretical study of the effective Zeeman spin- and non-linear-splitting of a single spherical quantum dot based on the 8\\times 8~\\mathbf {k}\\bdot \\mathbf {p} Hamiltonian model. The effect of spin-hybridization on conduction band states is pointed out as the main source of the strong dependence of Landè factors and effective masses on external fields. The topology of the electronic orbitals is highly sensitive to the magnetic field tuning and to the spin polarization. The electron, hole and excitonic g-factors, as well as the diamagnetic coefficient are calculated for CdTe semiconductor quantum dots. Different systematic experimental methods are proposed in order to determine the behaviour of the electronic properties under analysis as a function of magnetic field and confinement geometry. Complementary optical transitions, in Faraday and Voigt configurations, can be used in the determination of electron, hole and exciton Landè factors, effective magnetic masses and diamagnetic coefficients.

  10. 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.

  11. Transformation of Ramsey electromagnetically induced absorption into magnetic-field induced transparency in a paraffin-coated Rb vapor cell.

    PubMed

    Moon, Han Seb; Kim, Ho-Jung

    2014-07-28

    We report on magnetic-field induced transparency (MIT) based on Ramsey electromagnetically induced absorption (EIA) in a paraffin-coated Rb vapor cell. Changing the laser polarization from linear to circular in the presence of a weak residual transverse magnetic field to the laser propagation, the narrow absorption due to the Ramsey EIA transformed into the transparency due to MIT of the 5S1/2 (F = 2)-5P3/2 (F' = 3) transition of 87Rb in the paraffin-coated Rb vapor cell. The spectral widths of the EIA and MIT in the Hanle configuration were measured to be 0.6 mG (425 Hz) and 1.2 mG, respectively. MIT depended on the long preservation time of the ground-state coherent spin states and the transverse magnetic field. From the numerical results, the crossover between the Ramsey EIA and the MIT could be illustrated as the superposition of both signals. PMID:25089479

  12. Magnetic field induced polarization and magnetoelectric effect of Ba0.8Ca0.2TiO3-Ni0.2Cu0.3Zn0.5Fe2O4 nanomultiferroic

    NASA Astrophysics Data System (ADS)

    Sadhana, Katlakunta; Ramana Murthy, Sarabu; Jie, Shang; Xie, Yali; Liu, Yiwei; Zhan, Qingfeng; Li, Run-Wei

    2013-05-01

    The xBa0.8Ca0.2TiO3-(1 - x)NiCuZn ferrite (x = 0.1, 0.3, 0.5, 0.7, and 0.9) nanocomposites were prepared by using sol-gel method. The densification of these composites was carried out using microwave sintering method. The magnetic field induced changes in the ferroelectric polarization loop may support the possible magnetoelectric coupling between Ba0.8Ca0.2TiO3 and NiCuZn ferrite phases. The observed change in ferroelectric polarization with applied magnetic field proves the coupling between magnetic and ferroelectric order parameters. The loop change is observed with the composition and with magnetic field. The magnetoelectric coefficient of the nanocomposite with x = 0.3 shows a value of 280 mV/cm Oe is obtained.

  13. 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

  14. 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.

  15. Direct evidence on magnetic-field-induced phase transition in a NiCoMnIn ferromagnetic shape memory alloy under a stress field.

    SciTech Connect

    Wang, Y. D.; Ren, Y.; Huang, E. W.; Nie, Z. H.; Wang, G.; Liu, Y. D.; Deng, J. N.; Zuo, L.; Choo, H.; Liaw, P .K.; Brown, D. E.; Univ. of Tennessee; Northeastern Univ.; Northern Illinois Univ.

    2007-01-01

    The magnetoelasticity and magnetoplasticity behaviors of a Ni-Co-Mn-In ferromagnetic shape memory alloy (FSMA) induced by the reverse phase transformation interplayed under multiple (temperature, magnetic, and stress) fields were captured directly by high-energy synchrotron x-ray diffraction technique. The experiments showed the direct experimental evidence of that a stress ({approx}50 MPa) applied to this material made a complete recovery of the original orientations of the martensite variants, showing a full shape memory effect. This finding offers the in-depth understanding the fundamental properties and applications of the Ni-Co-Mn-In FSMA with the magnetic-field-induced reverse transformation.

  16. Direct evidence on magnetic-field-induced phase transition in a NiCoMnIn ferromagnetic shape memory alloy under a stress field

    SciTech Connect

    Wang, Y. D.; Ren Yang; Huang, E. W.; Nie, Z. H.; Wang, G.; Liu, Y. D.; Deng, J. N.; Zuo, L.; Choo, H.; Liaw, P. K.; Brown, D. E.

    2007-03-05

    The magnetoelasticity and magnetoplasticity behaviors of a Ni-Co-Mn-In ferromagnetic shape memory alloy (FSMA) induced by the reverse phase transformation interplayed under multiple (temperature, magnetic, and stress) fields were captured directly by high-energy synchrotron x-ray diffraction technique. The experiments showed the direct experimental evidence of that a stress ({approx}50 MPa) applied to this material made a complete recovery of the original orientations of the martensite variants, showing a full shape memory effect. This finding offers the in-depth understanding the fundamental properties and applications of the Ni-Co-Mn-In FSMA with the magnetic-field-induced reverse transformation.

  17. 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.

  18. 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.

  19. 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.

  20. 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

    NASA Astrophysics Data System (ADS)

    Eliav, U.; Haimovich, A.; Goldbourt, A.

    2016-01-01

    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 7Li-13C distances in a complex of lithium, glycine, and water. Discussion of the regime for which such an approach is valid is given.

  1. Elastic effects of long-range quadrupolar interactions in nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Faetti, S.; Evangelista, L. R.; Barbero, G.

    1998-12-01

    We discuss the role of the quadrupolar interaction in nematic liquid crystal samples in the shape of a slab, limiting the study to planar deformations. Our analysis shows that this interaction gives rise to a bulk energy density that, in the elastic approximation, depends linearly on the second spatial derivative and quadratically on the first spatial derivative of the nematic orientation. We show that this bulk energy density can be separated in a surfacelike term, which gives rise just to a surface contribution, plus a term having the usual form. Both terms depend on the first derivative of the tilt angle and are proportional to the square of the electrical quadrupolar density. The bulk term, quadratic in the first derivative of the tilt angle, renormalizes the usual elastic energy density connected to the short-range forces. The bulk elastic constant of quadrupolar origin can be negative and one order of magnitude smaller than the effective elastic constants for typical nematic liquid crystals. According to our analysis this interaction is responsible for an elastic anisotropy proportional to the square of the electrical quadrupolar density, which depends on the nematic orientation. The surfacelike term is proportional to the first derivative of the tilt angle. It calls mind to the splay-bend elastic term, although the tilt angle dependence is more complicated. The relevant elastic constant is of the same order of magnitude as the bulk one, due to the same interaction. We evaluate also the energy density in the surface layers, where the quadrupolar interaction is restricted by the surface. In this case we show that the free energy contribution due to the surface layers is reduced to a classical anchoring energy. The solution of the variational problem by means of a simple version of the density functional theory is presented.

  2. 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.

  3. 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.

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

    PubMed

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

    2015-10-21

    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 the bulk phases and the intrinsic polarization of the interface. The coefficient of the dielectro-Marangoni effect (surface flow due to gradient of the normal electric field) is found. A model of the Langevin type for the surface dipole moment and the intrinsic surface polarizability is presented. PMID:26493922

  5. 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 the bulk phases and the intrinsic polarization of the interface. The coefficient of the dielectro-Marangoni effect (surface flow due to gradient of the normal electric field) is found. A model of the Langevin type for the surface dipole moment and the intrinsic surface polarizability is presented.

  6. Orientation control of a synthetic columnar perfluorinated supramolecular dendrimer: Surface anchoring and magnetic-field induced alignments

    NASA Astrophysics Data System (ADS)

    Ki Yoon, Dong; Rim Lee, Su; Ho Kim, Yun; Seong, Baek-Seok; Soo Han, Young; Jung, Hee-Tae

    2006-11-01

    Orientation ordering of a synthetic perfluorinated supramolecule containing a hydrophilic core group and perfluorinated tails is strongly affected by the functionality, molecular shape, surface anchoring and magnetic field. Small-angle neutron scattering (SANS), synchrotron X-ray diffraction, polarized light microscopy (PLM) and transmission electron microscopy (TEM) results show that the molecule exhibits hexagonal columnar mesophase upon cooling from isotropic phase. The orientation of the columns was controlled by surface anchoring; the columnar axes were perpendicular to the hydrophobic carbon substrates, while planar alignment is favored on hydrophilic surfaces. Furthermore, the columnar domains align with the magnetic field lines, which is due to diamagnetism of these fan-shaped molecules containing aromatic rings. We show that the magnetic-induced alignment is much effective for the large-scale control of the orientation of the perfluorinated columnar mesophase.

  7. 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.

  8. Magnetic field-induced cluster formation and variation of magneto-optical signals in zinc-substituted ferrofluids

    NASA Astrophysics Data System (ADS)

    Nair, Swapna. S.; Rajesh, S.; Abraham, V. S.; Anantharaman, M. R.; Nampoori, V. P. N.

    2006-10-01

    Fine magnetic particles (size≅100 Å) belonging to the series Zn xFe 1-xFe 2O 4 were synthesized by cold co-precipitation methods and their structural properties were evaluated using X-ray diffraction. Magnetization studies have been carried out using vibrating sample magnetometry (VSM) showing near-zero loss loop characteristics. Ferrofluids were then prepared employing these fine magnetic powders using oleic acid as surfactant and kerosene as carrier liquid by modifying the usually reported synthesis technique in order to induce anisotropy and enhance the magneto-optical signals. Liquid thin films of these fluids were prepared and field-induced laser transmission through these films was studied. The transmitted light intensity decreases at the centre with applied magnetic field in a linear fashion when subjected to low magnetic fields and saturate at higher fields. This is in accordance with the saturation in cluster formation. The pattern exhibited by these films in the presence of different magnetic fields was observed with the help of a CCD camera and was recorded photographically.

  9. 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.

  10. dc- and ac-magnetic field-induced strain effects in ferromagnetic shape memory composites of Ni-Mn-Ga single crystal and polyurethane polymer

    NASA Astrophysics Data System (ADS)

    Zeng, Min; Or, Siu Wing; Chan, Helen Lai Wa

    2010-05-01

    Ferromagnetic shape memory composites of multilayer and sandwich types were fabricated by laminating Ni-Mn-Ga single-crystal plates with polyurethane (PU) polymer plates. The dc- and ac-magnetic field-induced strains (MFISs) in the composites were measured as functions of both magnetic field and mechanical load, and the results were compared with those of the single crystal. It was found that the load-free dc-MFISs were 5.6%, 1.5%, and 0.8%, while the load-free ac-MFISs were 0.3%, 0.8%, and 0.5% in the single crystal, multilayer composite, and sandwich composite, respectively. The relatively smaller load-free dc-MFISs and larger load-free ac-MFISs in the composites than the single crystal originated from the stress bias of the Ni-Mn-Ga plates by the PU plates in the composites. The dc-MFISs of all samples and the ac-MFISs of the composites decreased with the increase in mechanical load amplitude, while the ac-MFIS of the single crystal peaked at 1.6 MPa load.

  11. 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.

  12. 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.

  13. Use of quadrupolar nuclei for quantum-information processing by nuclear magnetic resonance: Implementation of a quantum algorithm

    SciTech Connect

    Das, Ranabir; Kumar, Anil

    2003-09-01

    Physical implementation of quantum-information processing by liquid-state nuclear magnetic resonance, using weakly coupled spin-(1/2) nuclei of a molecule, is well established. Nuclei with spin>1/2 oriented in liquid-crystalline matrices is another possibility. Such systems have multiple qubits per nuclei and large quadrupolar couplings resulting in well separated lines in the spectrum. So far, creation of pseudopure states and logic gates has been demonstrated in such systems using transition selective radio-frequency pulses. In this paper we report two developments. First, we implement a quantum algorithm that needs coherent superposition of states. Second, we use evolution under quadrupolar coupling to implement multiqubit gates. We implement the Deutsch-Jozsa algorithm on a spin-(3/2) (2 qubit) system. The controlled-NOT operation needed to implement this algorithm has been implemented here by evolution under the quadrupolar Hamiltonian. To the best of our knowledge, this method has been implemented for the first time in quadrupolar systems. Since the quadrupolar coupling is several orders of magnitude greater than the coupling in weakly coupled spin-(1/2) nuclei, the gate time decreases, increasing the clock speed of the quantum computer.

  14. 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.

  15. 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.

  16. Direct Characterization of Metal-Metal Bonds between Nuclei with Strong Quadrupolar Interactions via NMR Spectroscopy.

    PubMed

    Perras, Frédéric A; Bryce, David L

    2014-11-20

    Metal-metal bonds can be difficult to characterize directly. We demonstrate that J couplings between metal nuclei experiencing strong quadrupolar interactions can be easily measured from well-defined splittings in NMR spectra of powdered samples. Using (69/71)Ga NMR, it is shown that homonuclear J coupling, which is four orders of magnitude smaller than the quadrupolar coupling in a series of compounds featuring gallium-gallium bonds, can be extracted with a 2-D NMR experiment. The dependence of the multiplets on crystal symmetry reveals information on the structures of two Ga-Ga-bonded compounds for which diffraction data are unavailable. Interpretation of the data in a molecular orbital framework provides insight into the nature of the metal-metal bond. PMID:26276493

  17. Fundamental measure density functional theory study of liquid-vapor interface of dipolar and quadrupolar fluids.

    PubMed

    Warshavsky, V B; Zeng, X C

    2013-10-01

    We have studied interfacial structure and properties of liquid-vapor interfaces of dipolar fluids and quadrupolar fluids, respectively, using the classical density functional theory (DFT). Towards this end, we employ the fundamental measure DFT for a reference hard-sphere (HS) part of free energy and the modified mean field approximation for the correlation function of dipolar or quadrupolar fluid. At low temperatures we find that both the liquid-vapor interfacial density profile and orientational order parameter profile exhibit weakly damped oscillatory decay into the bulk liquid. At high temperatures the decay of interfacial density and order parameter profiles is entirely monotonic. The scaled temperature ? = 1 - T/T(c) that separates the two qualitatively different interfacial structures is in the range 0.10-0.15. At a given (dimensionless) temperature, increasing the dipolar or quadrupolar moment enhances the density oscillations. Application of an electric field (normal to the interface) will damp the oscillations. Likewise, at the given temperature, increasing the strength of any multipolar moment also increases the surface tensions while increasing the strength of the applied electric field will reduce the surface tensions. The results are compared with those based on the local-density approximations (LDA) for the reference HS part of free energy as well as with results of numerical experiments. PMID:24116570

  18. 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.

  19. Two-plate vs. four-plate azimuthal quadrupolar excitation for FT-ICR mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jackson, George S.; Hendrickson, Christopher L.; Reinhold, Bruce B.; Marshall, Alan G.

    1997-11-01

    Azimuthal quadrupolar excitation has become one of the most useful techniques for ion axialization and translational cooling for FT-ICR mass spectrometry, leading to order(s)-of-magnitude improvement in mass selectivity, resolving power, mass accuracy, remeasurement efficiency, etc. Recently, Hendrickson et al. (J. Am. Soc. Mass Spectrom. 6 (1995) 448-452) showed that axialization may be achieved by 2-plate azimuthal quadrupolar excitation, in which an rf voltage of the same amplitude and phase is applied to a single pair of opposed side electrodes, while grounding the other orthogonal opposed pair (rather than applying an rf voltage of equal amplitude but shifted in phase by 180° to the second pair as in prior 4-plate experiments). Here, we analyze theoretically and test experimentally the performance of these two electrode geometries. As previously shown, either geometry can achieve axialization by resonant excitation at the unshifted ion cyclotron frequency, ([omega]c = qB/m). For either excitation configuration, excitation at twice the reduced cyclotron frequency, 2[omega]+, leads to unwanted exponential growth of the ion cyclotron radius. For 2-plate geometry, we show that excitation at twice the axial oscillation frequency, 2 [omega]z, leads to exponential growth in z-oscillation amplitude, whereas excitation at [omega]c = [omega]+ + [omega]- and [omega]p = [omega]+ - [omega]- ([`]parametric' frequency) leads to complex ion behavior. Finally, we discuss the effect of azimuthal quadrupolar excitation amplitude (as well as frequency) on axialization.

  20. Kn 26, a new quadrupolar planetary nebula

    NASA Astrophysics Data System (ADS)

    Guerrero, M. A.; Miranda, L. F.; Ramos-Larios, G.; Vázquez, R.

    2013-03-01

    Once classified as an emission line source, the planetary nebula (PN) nature of the source Kn 26 has only recently been recognized in digital sky surveys. To investigate the spectral properties and spatio-kinematical structure of Kn 26, we have obtained high spatial-resolution optical and near-IR narrow-band images, high-dispersion long-slit echelle spectra, and intermediate-resolution spectroscopic observations. The new data reveal an hourglass morphology typical of bipolar PNe. A detailed analysis of its morphology and kinematics discloses the presence of a second pair of bipolar lobes, making Kn 26 a new member of the subclass of quadrupolar PNe. The time lapse between the ejection of the two pairs of bipolar lobes is much shorter than their dynamical ages, implying a rapid change in the preferential direction of the central engine. The chemical composition of Kn 26 is particularly unusual among PNe, with a low N/O ratio (as for type II PNe) and a high helium abundance (as for type I PNe), although not atypical among symbiotic stars. Such an anomalous chemical composition may have resulted from the curtailment of the time in the asymptotic giant branch by the evolution of the progenitor star through a common envelope phase. Based on observations made with the Nordic Optical Telescope (NOT) and the William Herschel Telescope (WHT) on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC), the 2.1-m telescope of the Observatorio Astronómico Nacional at the Sierra de San Pedro Mártir (OAN-SPM), and the 1.5-m telescope at the Observatorio de Sierra Nevada (OSN), Granada, Spain. NOT is operated jointly by Denmark, Finland, Iceland, Norway, and Sweden. WHT is operated by the Isaac Newton Group. The 2.1-m telescope at the OAN-SPM is a national facility operated by the Instituto de Astronomía of the Universidad Nacional Autónoma de México. The 1.5-m telescope at the OSN is operated by the Instituto de Astrofísica de Andalucía (IAA).The data presented here were obtained in part with ALFOSC, which is provided by the IAA under a joint agreement with the University of Copenhagen and NOTSA.FITS files for spectra and images are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A53

  1. 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

  2. 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.

  3. 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…

  4. 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.

  5. 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.

  6. 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.

  7. Nonresonant Photon Dressing in Spin One Quadrupolar Systems

    NASA Astrophysics Data System (ADS)

    Zhuang, Yi-Li.

    The main part of this thesis is a study of the effects of nonresonant photon dressing on spin 1 pure quadrupolar system with symmetric EFG. Energy levels of spin 1 nuclei dressed by linearly or circularly polarized photons were theoretically derived and numerically analyzed. In both cases, the degeneracy of m_zeta equals +/-1 states is not lifted, so only one line can be excited and it is shifted up in frequency. The energy levels are found to depend on the angle theta between the principle EFG zeta axis and the dressing field. Since most NQR samples are polycrystalline, a general formula for powder patterns due to photon dressing was derived and numerical examples were plotted for the case of linearly polarized photons, spin 1 and {3over2 }, and circularly polarized photons, spin 1. In all of these cases, NQR lines are broadened, and have a peak located at theta = 90 ^circ. Energy levels of photon dressed protons in zero static field are analyzed for the purpose of discussing ^{14}N^in-echo time. Protons are shown to reorient between +/-{1over2 } states rapidly, so that their local field tends to average out. Powdered crystalline samples Trimethylamine (TMA), Triethylenediamine (TED), and Hexanethylenetetramine (HMT) all with symmetric EFG were experimentally investigated by ^{14}N NQR. For circularly polarized dressing of 25 G peak, no NQR frequency shift was observed; a monotonic line narrowing was observed in TMA and TED, but not HMT; fine structure details of TED and HMT were revealed as a result of the line narrowing, but the cause of the fine structure was not determined. Experimental results are in good agreement with theory. A minor portion of this thesis is to study the effects of annealing and hydrogenation on short-range order in amorphous III-V compounds through NMR linewidth. alpha - GaP, alpha - GaAs, and alpha - GaAs: H grown on single crystal alkali halide substrates by rf-sputtering have been studied. The results were compared with that of previous measurements on alpha - GaP and alpha - GaAs grown on different substrates at different temperature. The study showed that sample microstructure is directly influenced by sample preparation conditions, however, the presence of 10% hydrogen in the sample did not influence the NMR linewidth at room temperature nor the annealing behavior.

  8. 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.

  9. 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.

  10. 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.

  11. Magnetic field induced changes in the critical exponent {beta} of the chiral triangular antiferromagnet CsMnBr{sub 3} in the presence of an electric field (abstract)

    SciTech Connect

    Visser, D.; Monteith, A.R.; Bargawi, A.Y.; Zeiske, T.

    1997-04-01

    The magnetic moments in the triangular antiferromagnetic CsMnBr{sub 3} order at T{sub N}=8.3 K with a frustration of the magnetic moments in a 120{degree} type magnetic structure. The magnetic moments are either ordered in a clockwise or an anticlockwise direction resulting in a chirality ordering, which is characterized by the critical exponent of the magnetic sublattice magnetization {beta}=0.25. It has been shown that an electric field applied along the [110] direction removes the chiral ordering and a linear Ising-like phase will be established; consequently, the value of {beta} decreases. The subsequent application of a magnetic field of B=4 T along the [100] direction causes the critical exponent {beta} to increase. The magnetic phase diagram of CsMnBr{sub 3} does not change due to the introduction of an electric field.{copyright} {ital 1997 American Institute of Physics.}

  12. 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.

  13. Abstract: Quadrupolar interactions and structural instabilities in PrAg1 - xCux

    NASA Astrophysics Data System (ADS)

    Gotaas, J. A.; Kouvel, J. S.; Brun, T. O.; Cable, J. W.

    1982-03-01

    In order to elucidate the unusually strong quadrupole-quadrupole interactions discovered earlier in PrAg, magnetic and neutron diffraction studies are being made of the pseudobinary compounds PrAg1-xCux. For PrAg0.75Cu0.25, which, like PrAg, has a cubic CsCl-type structure, analysis of high-field magnetization data above the antiferromagnetic Néel point (TN˜9 K) shows that the effective biquadratic (quadrupolar) coupling is about twice as strong as in PrAg, whereas the average bilinear exchange coupling is slightly weaker. PrAg0.5Cu0.5, which has a CsCl-type structure at room temperature, was found to transform to an orthorhombic FeB-type structure (similar to that of PrCu) when it is cooled below ˜150 K. Detailed comparison of the two structures of PrAg0.5Cu0.5 indicates that the instability of the CsCl-type structure probably stems from the softening of certain zone-boundary phonons, which presumably grows as x increases towards 0.5. Such phonons would account for strong effective quadrupolar interactions of negative (antiferro) sign, precisely of the type seen in PrAg and PrAg0.75 Cu0.25. a) Work supported by NSF Grant No. DMR 78-12777. b) Work supported by the U.S Department of Energy. c) Work sponsored by the U. S. Department of Energy under contract W-7405-eng-26 with the Union Carbide Corp. 1 T. O. Brun, J. S. Kouvel, and G. H. Lander, Phys. Rev. B 13, 5007 (1976).

  14. Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe1.64Ga0.36O3 oxide

    NASA Astrophysics Data System (ADS)

    Bhowmik, R. N.; Vijayasri, G.

    2015-06-01

    We have studied current-voltage (I-V) characteristics of α-Fe1.64Ga0.36O3, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔVP) 0.345(± 0.001) V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (˜500-700%), magnetoresistance (70-135 %) and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.

  15. 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

  16. 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.

  17. Lineshape Variations of a Spin- {1}/{2} Nucleus Coupled to a Quadrupolar Spin Subjected to RF Irradiation

    NASA Astrophysics Data System (ADS)

    Murali, N.; Rao, B. D. Nageswara

    In this paper, the lineshape variations in the multiplet structure of a spin- {1}/{2} nucleus I ( 13C) scalar coupled to a quadrupolar spin S ( 2H) as a function of the strength of the irradiating radiofrequency field applied in the vicinity of the S-spin resonance and of the relaxation times of the latter are presented. These lineshapes were simulated using an exact theoretical treatment based on the solution of the complete-density-matrix equations (including both coherent and incoherent parts) in the presence of RF irradiation of spin S. The relaxation mechanisms for the spin system include chemical-shift anisotropy (CSA) for spin I, quadrupolar interaction for spin S, and the mutual dipole-dipole interaction between I and S. The simulations incorporate interference effects arising from the simultaneous presence of these tensor interactions of the same order, which cause both lineshape variations as well as dynamic frequency shifts. The RF field strength of the irradiation was varied over a wide range, and the two cases of (i) complete and (ii) incomplete "washing out" of the spin coupling between the nuclei are considered separately. The simulations illustrate the dependence of the spectrum of spin I on various parameters such as the value of the scalar coupling constant, the quadrupolar relaxation times, and the irradiation strength in commonly realized experimental context. In addition, a simpler theory for the case of completely washed out scalar coupling in which the scalar interaction is treated exclusively as a relaxation process is presented in the Appendix. The procedure given in this paper is applicable to lineshape calculations for any spin- {1}/{2} -spin-1 coupled system.

  18. 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.

  19. 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.

  20. 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 achieved.

  1. Quadrupolar NMR Spin Relaxation Calculated Using Ab Initio Molecular Dynamics: Group 1 and Group 17 Ions in Aqueous Solution.

    PubMed

    Badu, Shyam; Truflandier, Lionel; Autschbach, Jochen

    2013-09-10

    Electric field gradient (EFG) fluctuations for the monoatomic ions (7)Li(+), (23)Na(+), (35)Cl(-), (81)Br(-), and (127)I(-) in aqueous solution are studied using Car-Parrinello ab initio molecular dynamics (aiMD) simulations based on density functional theory. EFG calculations are typically performed with 1024 ion-solvent configurations from the aiMD simulation, using the Zeroth Order Regular Approximation (ZORA) relativistic Hamiltonian. Autocorrelation functions for the spherical EFG tensor elements are computed, transformed into the corresponding spectral densities (under the extreme narrowing condition), and subsequently converted into NMR quadrupolar relaxation rates for the ions. The relaxation rates are compared with experimental data. The order of magnitude is correctly predicted by the simulations. The computational protocol is tested in detail for (81)Br(-). PMID:26592401

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

    SciTech Connect

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

    2015-08-04

    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.

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

    DOE PAGESBeta

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

    2015-08-04

    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 inmore » 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

  4. 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.

  5. 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

  6. Quadrupolar-coupling-specific binomial pulse sequences for in vivo 23Na NMR and MRI.

    PubMed

    Laustsen, Christoffer; Ringgaard, Steffen; Pedersen, Michael; Nielsen, Niels Chr

    2010-09-01

    Aimed at selective detection of (23)Na with specific quadrupolar couplings for in vitro NMR and MRI, we present a series of quadrupolar binomial pulse sequences offering high specificity with respect to the quadrupolar couplings of the excited species. It is demonstrated that pulse sequences with an increasing number of elements, e.g., 11, 121, 1331, 14641, and 15101051, with the units representing flip angles smaller than the 90 degrees pulses typically encountered in binomial spin-1/2 solvent suppression experiments, and different phase combinations may provide a high degree of flexibility with respect to quadrupolar coupling selectivity and robustness towards rf inhomogeneity. This may facilitate efficient separation of, for example, intra and extracellular (23)Na in tissues with efficient control of the excitation (or suppression) of central as well as satellite transitions through on- and off-resonance irradiation. The pulse sequences are described in terms of their analogy to binomial liquid-state NMR solvent suppression experiments and demonstrated numerically and experimentally through NMR and MRI experiments on a 7 T horizontal small-bore animal magnet system. PMID:20673642

  7. 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

  8. Measurement of Dipolar Interaction of Quadrupolar Nuclei in Solution Using Multiple-Quantum NMR Spectroscopy

    PubMed

    Eliav; Navon

    1996-11-01

    Relaxation resulting from the modulation of dipolar interaction is commonly used for estimating distances in molecules in solutions. However, for most nuclei with spin I > ½ the single-quantum-transition relaxation by dipolar interaction is masked by quadrupolar relaxation. In the present study, it is shown that even in systems where single-quantum relaxation times are dominated by quadrupolar interaction, dipolar relaxation can be measured by following the -m $\\leftrightarrow$ m transitions. This is demonstrated for 7Li in the complex [Li-Kryptofix 211]+X- (X = Cl, Br) dissolved in glycerol at temperatures for which slow motion prevails and no 1H-7Li NOE can be observed. The relaxation times that are most important for the assessment of the dipolar interaction of 7Li are -½ $\\leftrightarrow$ ½ and -${{3}\\over{2}}$ $\\leftrightarrow$ ${{3}\\over{2}}$ and they are measured by multiple-quantum-filtration techniques. For estimating the quadrupolar interaction, the relaxation times of the populations and those of the transitions ±½ $\\leftrightarrow$ ±${{3}\\over{2}}$ were measured. The longitudinal and transverse relaxation times of 6Li as well as the 1H-6Li NOE were also measured and, together with the 7Li measurements, were used to obtain the strengths of dipolar (D) and quadrupolar (chi) interactions. The experimental data were analyzed using several models to describe the motion. The model that gave the best fit and resulted in parameters that were physically meaningful encompassed a whole-body isotropic motion as well as internal anisotropic motion. For this particular model, the following values for the quadrupolar and the dipolar interactions strength were obtained: D(7Li)/2pi = 6.8 kHz, chi(7Li)/2pi = 85 kHz and D(6Li)/2pi = 1.4 kHz, chi(6Li)/2pi = 2.6 kHz. From the value of D, an estimate of the average lithium-proton distance was calculated to be 3.3 Å, which is in fair agreement with crystallographic studies. The sizes of the quadrupolar and dipolar interactions were independently confirmed by the 7Li NMR powder spectra of the complexes that were used for the solution studies. PMID:8980061

  9. 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.

  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. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Quantum spin liquid and electric quadrupolar states of single crystal Tb2+xTi2-xO7+y

    NASA Astrophysics Data System (ADS)

    Wakita, M.; Taniguchi, T.; Edamoto, H.; Takatsu, H.; Kadowaki, H.

    2016-02-01

    The ground states of the frustrated pyrochlore oxide Tb2+xTi2-xO7+y, sensitively depending on the small off-stoichiometry parameter x, have been studied by specific heat measurements using well characterized samples. Single crystal Tb2+xTi2-xO7+y boules grown by the standard floating zone technique are shown to exhibit concentration (x) gradient. This off-stoichiometry parameter is determined by precisely measuring the lattice constant of small samples cut from a crystal boule. Specific heat shows that the phase boundary of the electric quadrupolar state has a dome structure in the x-T phase diagram with the highest Tc ≃ 0.5 K at about x = 0.01. This phase diagram suggests that the putative U(1) quantum spin-liquid state of Tb2+xTi2-xO7+y exists in the range x < xc ≃ -0.0025, which is separated from the quadrupolar state via a first-order phase-transition line x = xc.

  17. 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 encoding module for the recently developed NMR remote detection experiment. The feasibility of using hyperpolarized xenon-129 gas as a sensor is discussed. This work also reports the use of an optical atomic magnetometer to detect the nuclear magnetization of Xe-129 gas, which has potential applicability as a detection module for NMR remote detection experiments.

  18. 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.

  19. Hydrogen atom in the presence of uniform magnetic and quadrupolar electric fields: integrability, bifurcations, and chaotic behavior.

    PubMed

    Iñarrea, M; Salas, J P; Lanchares, V

    2002-11-01

    We investigate the classical dynamics of a hydrogen atom in the presence of uniform magnetic and quadrupolar electric fields. After some reductions, the system is described by a two degree of freedom Hamiltonian depending on two parameters. On the one hand, it depends on the z component of the canonical angular momentum P(phi), which is an integral because the system is axially symmetric; and on the other it also depends on a parameter representing the relative field strengths. We note that this Hamiltonian is closely related to the one describing the generalized van der Waals interaction. We report three cases of integrability. The structure and evolution of the phase space are explored intensively by means of Poincaré surfaces of section when the parameters vary. In this sense, we find several bifurcations that strongly change the phase space structure. The chaotic behavior of the system is studied and three order-chaos transitions are found when the system passes through the integrable cases. Finally, the ionization mechanics is studied. PMID:12513630

  20. Bulk and interfacial properties of a dipolar-quadrupolar fluid in a uniform electric field: a density-functional approach.

    PubMed

    Warshavsky, V B; Zeng, X C

    2003-07-01

    We have studied the bulk and interfacial properties of a dipolar-quadrupolar fluid based on an extended modified mean-field density-functional theory. Effects of a uniform electric field on the bulk and interfacial properties are also studied. Results of the coexisting vapor-liquid densities, interfacial profiles of the density and orientation order parameters, the surface tension, and their dependence on the temperature, magnitude of molecule dipole and quadrupole moment, and the applied field are obtained. In general, we find that the applied field increases the critical temperature, broadens the vapor-liquid coexistence curves, and reduces the surface tension. We also find that if the quadrupole moment is positive, the reduction in the surface tension is greater when the applied field is in the direction from the vapor to the liquid phase than the reduction when the field is in the opposite direction. This apparent symmetry breaking by reversing the field direction may offer a molecular mechanism to explain the phenomenon of the sign preference in liquid droplet formation on charged condensation centers. PMID:12935128

  1. 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/m, 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.

  2. Chemical potential of quadrupolar two-centre Lennard-Jones fluids by gradual insertion

    NASA Astrophysics Data System (ADS)

    Vrabec, Jadran; Kettler, Matthias; Hasse, Hans

    2002-04-01

    The gradual insertion method for direct calculation of the chemical potential by molecular simulation is applied in the NpT ensemble to different quadrupolar two-centre Lennard-Jones fluids at high density state points. The results agree well with Widom's test particle insertion but show at very high densities significantly smaller statistical uncertainties. The gradual insertion method, which is coupled here with preferential sampling, extends the density range where reliable information on the chemical potential can be obtained. Application details are reported.

  3. 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.

  4. 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.

  5. Structure evolution and entropy change of temperature and magnetic field induced magneto-structural transition in Mn1.1Fe0.9P0.76Ge0.24

    NASA Astrophysics Data System (ADS)

    Yue, Ming; Liu, Danmin; Huang, Qingzhen; Wang, Tong; Hu, Fengxia; Li, Jingbo; Rao, Guanghui; Shen, Baogen; Lynn, Jeffery W.; Zhang, Jiuxing

    2013-01-01

    The compound Mn1.1Fe0.9P0.76Ge0.24 has been studied using neutron powder diffraction (NPD), differential scanning calorimeter (DSC), and magnetic measurements, in order to clarify the nature of the magnetic and structural transition and measure the associated entropy change (ΔS). The strongly first order transition occurs from a paramagnetic (PM) to a ferromagnetic (FM) phase and can be induced either by temperature or by an applied magnetic field. Our investigations indicate that the two processes exhibit identical evolutions regarding the crystal and magnetic structures, indicating they should have the same entropy change. We, therefore, conclude that the ΔSDSC obtained by the DSC method (where the transition is temperature induced) is valid also for the magnetically induced transition, thus avoiding uncertainties connected with the magnetic measurements. We have obtained the ΔSDSC = 33.8 J/kg . K for this sample upon cooling, which would increase to 42.7 J/kg . K for a impurity-free and completely homogeneous sample. For comparison, the magnetic entropy changes (ΔSM) induced by magnetic field and calculated using the Maxwell relation yields a ΔSM = 46.5J/kg . K, 38% higher than ΔSDSC. These entropy results are compared and discussed.

  6. Molecular dynamics of half-integer quadrupolar nuclei studied by QCPMG solid-state NMR experiments on static and rotating samples. Theory and simulations.

    PubMed

    Larsen, Flemming H

    2004-12-01

    Simulations of QCPMG NMR type experiments have been used to explore dynamic processes of half-integer quadrupolar nuclei in solids. By setting up a theoretical approach that is well suited for efficient numerical simulations the QCPMG type experiments have been analyzed regarding the effect of the magnitude of the EFG- and CSA-tensors, the spin-quantum number, different dynamical processes and MAS. Compared to the QE experiment the QCPMG experiment offers not only intensity gain by an order of magnitude and changes in overall lineshape as a function of the kinetic rate constant but the lineshape of the individual spin-echo sidebands is also very sensitive towards dynamics. Hereby a visual identification of the dynamics is obtained. In common for all the simulations the spin-echo sidebands are narrow in the slow (k< or =10(2) Hz) and the fast (k> or =10(7) Hz) dynamic regime whereas they are broadened in the intermediate regime 10(3)< or =k< or =10(7) Hz. The maximum intensity of the spin-echo sidebands for two-site jumps is highly dependent on the type of anisotropic interactions involved and the type of QCPMG experiment. Hence, in the fast limit the maximum intensity was 140% of the initial intensity when significant CSA was present or under the QCPMG-MAS experiment compared to 89 or 71% for the static experiment influenced by the quadrupolar interaction only. For 3-, 4-, and 6-site jumps the maximum intensity in the fast limit reached up to 339% of the intensity in the static limit. PMID:15546756

  7. Complete description of the interactions of a quadrupolar nucleus with a radiofrequency field. Implications for data fitting.

    PubMed

    Spencer, T Leigh; Goward, Gillian R; Bain, Alex D

    2013-06-01

    We present a theory, with experimental tests, that treats exactly the effect of radiofrequency (RF) fields on quadrupolar nuclei, yet retains the symbolic expressions as much as possible. This provides a mathematical model of these interactions that can be easily connected to state-of-the-art optimization methods, so that chemically-important parameters can be extracted from fits to experimental data. Nuclei with spins >1/2 typically experience a Zeeman interaction with the (possibly anisotropic) local static field, a quadrupole interaction and are manipulated with RF fields. Since RF fields are limited by hardware, they seldom dominate the other interactions of these nuclei and so the spectra show unusual dependence on the pulse width used. The theory is tested with (23)Na NMR nutation spectra of a single crystal of sodium nitrate, in which the RF is comparable with the quadrupole coupling and is not necessarily on resonance with any of the transitions. Both the intensity and phase of all three transitions are followed as a function of flip angle. This provides a more rigorous trial than a powder sample where many of the details are averaged out. The formalism is based on a symbolic approach which encompasses all the published results, yet is easily implemented numerically, since no explicit spin operators or their commutators are needed. The classic perturbation results are also easily derived. There are no restrictions or assumptions on the spin of the nucleus or the relative sizes of the interactions, so the results are completely general, going beyond the standard first-order treatments in the literature. PMID:23611427

  8. Off-Resonance Nutation NMR Spectroscopy of Half-Integer Quadrupolar Nuclei

    NASA Astrophysics Data System (ADS)

    Kentgens, A. P. M.

    The possibilities of off-resonance irradiation in nutation experiments of half-integer quadrupolar nuclei are demonstrated experimentally and theoretically. Off-resonance irradiation extends the applicability of nutation NMR spectroscopy at a given radiofrequency field strength to a larger range of quadrupole coupling constants. Moreover, it is possible to obtain several spectra with different resonance offsets on one spectrometer, thus facilitating the determination of the quadrupole parameters. A loss of signal to the uninformative zero-frequency signal which accompanies off-resonance irradiation can be avoided by using a frequency-stepped adiabatic half-passage or a soft selective 90° pulse as preparation for the experiment. Simulated off-resonance nutation spectra are presented as a function of quadrupole coupling constant and resonance offsets. The technique is demonstrated experimentally for a number of sodium compounds.

  9. Pulmonary MRI contrast using Surface Quadrupolar Relaxation (SQUARE) of hyperpolarized (83)Kr.

    PubMed

    Six, Joseph S; Hughes-Riley, Theodore; Lilburn, David M L; Dorkes, Alan C; Stupic, Karl F; Shaw, Dominick E; Morris, Peter G; Hall, Ian P; Pavlovskaya, Galina E; Meersmann, Thomas

    2014-01-01

    Hyperpolarized (83)Kr has previously been demonstrated to enable MRI contrast that is sensitive to the chemical composition of the surface in a porous model system. Methodological advances have lead to a substantial increase in the (83)Kr hyperpolarization and the resulting signal intensity. Using the improved methodology for spin exchange optical pumping of isotopically enriched (83)Kr, internal anatomical details of ex vivo rodent lung were resolved with hyperpolarized (83)Kr MRI after krypton inhalation. Different (83)Kr relaxation times were found between the main bronchi and the parenchymal regions in ex vivo rat lungs. The T1 weighted hyperpolarized (83)Kr MRI provided a first demonstration of surface quadrupolar relaxation (SQUARE) pulmonary MRI contrast. PMID:24144493

  10. Pulmonary MRI contrast using Surface Quadrupolar Relaxation (SQUARE) of hyperpolarized 83Kr?

    PubMed Central

    Six, Joseph S.; Hughes-Riley, Theodore; Lilburn, David M.L.; Dorkes, Alan C.; Stupic, Karl F.; Shaw, Dominick E.; Morris, Peter G.; Hall, Ian P.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2014-01-01

    Hyperpolarized 83Kr has previously been demonstrated to enable MRI contrast that is sensitive to the chemical composition of the surface in a porous model system. Methodological advances have lead to a substantial increase in the 83Kr hyperpolarization and the resulting signal intensity. Using the improved methodology for spin exchange optical pumping of isotopically enriched 83Kr, internal anatomical details of ex vivo rodent lung were resolved with hyperpolarized 83Kr MRI after krypton inhalation. Different 83Kr relaxation times were found between the main bronchi and the parenchymal regions in ex vivo rat lungs. The T1 weighted hyperpolarized 83Kr MRI provided a first demonstration of surface quadrupolar relaxation (SQUARE) pulmonary MRI contrast. PMID:24144493

  11. 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.

  12. 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

  13. 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.

  14. Magnetic-field-induced structural transitions in a ferrofluid emulsion

    NASA Astrophysics Data System (ADS)

    Ivey, Mark; Liu, Jing; Zhu, Yun; Cutillas, Serge

    2001-01-01

    A ferrofluid emulsion, subjected to a slowly increasing magnetic field, exhibits a complicated structural behavior: a gas of Brownian particles changes to columnar solid structures due to induced dipole interaction. Two transition (intermediate) structural regimes are observed: (i) randomly distributed chains and particles and (ii) distinct thin columns and randomly distributed chains and particles. Three structural transition magnetic fields are found, one marking each structural transition, from the initial to the final structural regime. A structural diagram of the structural transition magnetic fields, HC, versus particle volume fractions, φ, is constructed experimentally. Theoretical models of scaling calculations, based upon the dominant magnetic interaction in each structural regime, give the three structural transition magnetic-field relations as HC1~φ-1/2, HC2~φ-1/4, and HC3~(φγ/G2)exp(πG/ φ(γ/2)), where γ=0.39 and G=0.29 for our sample. The final end shape of columns and the relative position between columns show that the end-end repulsion between chains is important in the structural formation.

  15. Magnetic-field-induced optical transmittance in colloidal suspensions

    SciTech Connect

    Martin, J.E.; Hill, K.M.; Tigges, C.P.

    1999-05-01

    Through simulation and experiment we demonstrate that when a magnetic field is applied to a suspension of magnetic particles, the optical attenuation length along the direction of the field increases dramatically, due to the formation of chainlike structures that allow the transmission of light between the strongly absorbing particles. This phenomenon is interesting for two reasons; first, there might be practical applications for this effect, such as optical-fiber-based magnetic field sensors, and second, measuring the time evolution of the optical attenuation length enables us to determine the kinetics of structure formation, which can be compared to the predictions of simulation and theory. In agreement with both simulation and theory, the optical attenuation length increases as a power of time, but much less light is actually transmitted than expected, especially at higher particle concentrations. We conclude that particle roughness, which is not included in either theory or simulation, plays a significant role in structural development, by pinning structures into local minima. {copyright} {ital 1999} {ital The American Physical Society}

  16. 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

  17. Static Magnetic Field Induced Stochastic Resonance in Gene Expression

    NASA Astrophysics Data System (ADS)

    Brady, Megan; Frisch, Paul; McLeod, Kenneth; Laramee, Craig

    2012-02-01

    Biological systems are naturally complex, making singular responses difficult to detect. However, when the emergent behavior is investigated, the collective properties may be observed and characterized. These responses to external stimuli at are often evident at the genomic level. When an optimal dose of external noise is used to perturb the system, it may work in synergy with the system's intrinsic noise to produce a change in stable state. This phenomenon, known as stochastic resonance (SR), is responsible for shifts in gene expression. This paper proposes that static magnetic fields (SMFs) elicit a SR genomic response in biological systems under environmentally relevant exposures. Using single reporter biomarkers as well as gene expression microarrays, the responses of three cell model systems (MCF-10A; Rat-1; Caco-2) to SMF exposure were examined. Results show that while responses for a single gene do occur, they are difficult to replicate and are near the detection cutoff limits. However, the system as a whole displays a shift in the pattern of gene expression. The replication of this pattern across different experimental platforms provides evidence that the cells are responding to the noise presented by the SMFs.

  18. 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.

  19. 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

  20. Order-parameter textures and boundary conditions in rotating vortex-free sup 3 He- B

    SciTech Connect

    Korhonen, J.S.; Gongadze, A.D.; Janu, Z.; Kondo, Y.; Krusius, M.; Mukharsky, Y.M.; Thuneberg, E.V. Institute of Physics, Georgian Academy of Sciences, 380077 Tbilisi Institute for Physical Problems, Academy of Sciences, 117334 Moscow Research Institute for Theoretical Physics, University of Helsinki, 00170, Helsinki )

    1990-09-03

    The order-parameter texture has been studied in rotating {sup 3}He-{ital B} in the vortex-free state with NMR techniques. A sequence of textural phase transitions is observed with increasing rotation speed. It is generated by competing interactions with magnetic field, surfaces, and rotation. Two surface interactions are extracted: the susceptibility anisotropy at the wall and the gyromagnetism due to a magnetic-field-induced surface supercurrent. The results are consistent with an order-parameter structure approaching the planar state with diffuse quasiparticle scattering at the wall.

  1. Q.E.COSY: determining sign and size of small deuterium residual quadrupolar couplings using an extended E.COSY principle.

    PubMed

    Tzvetkova, Pavleta; Luy, Burkhard

    2016-05-01

    Residual quadrupolar couplings contain important structural information comparable with residual dipolar couplings. However, the measurement of sign and size of especially small residual quadrupolar couplings is difficult. Here, we present an extension of the E.COSY principle to spin systems consisting of a Spin 1 coupled to a spin ½ nucleus, which allows the determination of the sign of the quadrupolar coupling of the Spin 1 nucleus relative to the heteronuclear coupling between the spins. The so-called Q.E.COSY approach is demonstrated with its sign-sensitivity using variable angle NMR, stretched gels and liquid crystalline phases applied to various CD and CD3 groups. Especially the sign-sensitive measurement of residual quadrupolar couplings that remain unresolved in conventional deuterium 1D spectra is shown. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26763050

  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 fundamental coordination chemistry of strontium present in the sol, the homogeneity of the ceramic was substantially enhanced, and the resulting electronic properties were improved. In another application of the new technique which have been developed, 87Sr NMR was employed to study the metal ion binding properties of alpha-Lactalbumin. The NMR data was fitted into a model with one high affinity and one low affinity site in alpha-Lactalbumin. The calculation of the correlation time, quadrupolar coupling constant provided the opportunity to study the location and the structure of the binding sites. In the application of the new technique in the area of biology, 25Mg NMR was employed to study the metal ion binding properties of bacteriorhodopsin. We presented the results of our studies regarding to two important questions in the photo conversion process: (1) The number of metal binding sites and their binding constants; and (2) What is the role of metal cations in the proton dissociation process/proton transfer (e.g., the key issue of the switch of the proton pump)? 113Cd NM of metal-bR complexes was employed as a probe of the chemical structure of bR calcium binding sites. We discuss the results in terms of the possible involvement of the metal cations in the bR function.

  3. Identification of Quadrupolar Excitation Channels at the {ital L}{sub 3} Edge of Rare-Earth Compounds

    SciTech Connect

    Bartolome, F.; Tonnerre, J.M.; Seve, L.; Raoux, D.; Chaboy, J.; Garcia, L.M.; Krisch, M.; Kao, C.C.

    1997-11-01

    Resonant inelastic x-ray scattering spectra are recorded at the L{sub 3} absorption edge of rare-earth ions in R{sub 2}Fe{sub 14}B . In all cases, weak resonances are observed at energies below the dipolar white line resonance, originating from 2p{r_arrow}4f quadrupolar excitations. Their energy position is in excellent agreement with that of preedge features in the x-ray magnetic circular dichroism (XMCD) spectra of the same samples. Our results therefore evidence the systematic appearance of quadrupolar excitation channels and the importance of their inclusion in the correct interpretation of the XMCD at the L{sub 3} edges of rare-earth systems. {copyright} {ital 1997} {ital The American Physical Society}

  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 applicability. This is demonstrated by (27)Al 3QMAS experiments on 9Al(2)O(3). 2B(2)O(3) and the mineral andalusite. In the latter compound, Al experiences a quadrupolar-coupling constant of 15.3 MHz in one of the sites. Finally a 5QMAS spectrum on 9Al(2)O(3). 2B(2)O(3) demonstrates the sensitivity enhancement of this experiment using a double frequency sweep. PMID:11097810

  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 muscle tissue. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26837061

  6. Separation of Quadrupolar and Magnetic Contributions to Spin-Lattice Relaxation in the Case of a Single Isotope

    NASA Astrophysics Data System (ADS)

    Suter, A.; Mali, M.; Roos, J.; Brinkmann, D.

    2000-04-01

    We present a NMR pulse double-irradiation method which allows one to separate magnetic from quadrupolar contributions in the spin-lattice relaxation. The pulse sequence fully saturates one transition while another is observed. In the presence of a ‖Δm‖ = 2 quadrupolar contribution, the intensity of the observed line is altered compared to a standard spin-echo experiment. We calculated analytically this intensity change for spins I = 1, {3}/{2}, {5}/{2}, thus providing a quantitative analysis of the experimental results. Since the pulse sequence we used takes care of the absorbed radiofrequency power, no problems due to heating arise. The method is especially suited when only one NMR sensitive isotope is available. Different cross-checks were performed to prove the reliability of the results obtained. The applicability of this method is demonstrated by a study of the plane oxygen 17O (I = {5}/{2}) in the high-temperature superconductor YBa2Cu4O8: the 17O spin-lattice relaxation rate consists of magnetic as well as quadrupolar contributions.

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

    PubMed

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

    2012-03-01

    The observation of a double-quantum filtered signal of quadrupolar nuclei (e.g. (23)Na) in solution has been traditionally interpreted as a sign for anisotropic reorientational motion. Ling and Jerschow (2007) have found that a (23)Na double-quantum signal is observed also in solutions of TmDOTPNa(5). 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. PMID:22342118

  8. 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.

  9. Deuterium Nuclear Spin-Lattice Relaxation Times and Quadrupolar Coupling Constants in Isotopically Labeled Saccharides

    NASA Astrophysics Data System (ADS)

    Bose-Basu, Bidisha; Zajicek, Jaroslav; Bondo, Gail; Zhao, Shikai; Kubsch, Meredith; Carmichael, Ian; Serianni, Anthony S.

    2000-06-01

    13C and 2H spin-lattice relaxation times have been determined by inversion recovery in a range of site-specific 13C- and 2H-labeled saccharides under identical solution conditions, and the data were used to calculate deuterium nuclear quadrupolar coupling constants (2H NQCC) at specific sites within cyclic and acyclic forms in solution. 13C T1 values ranged from ∼0.6 to 8.2 s, and 2H T1 values ranged from ∼79 to 450 ms, depending on molecular structure (0.4 M sugar in 5 mM EDTA (disodium salt) in 2H2O-depleted H2O, pH 4.8, 30°C). In addition to providing new information on 13C and 2H relaxation behavior of saccharides in solution, the resulting 2H1 NQCC values reveal a dependency on anomeric configuration within aldopyranose rings, whereas 2H NQCC values at other ring sites appear less sensitive to configuration at C1. In contrast, 2H NQCC values at both anomeric and nonanomeric sites within aldofuranose rings appear to be influenced by anomeric configuration. These experimental observations were confirmed by density functional theory (DFT) calculations of 2H NQCC values in model aldopyranosyl and aldofuranosyl rings.

  10. K-39 quadrupolar and chemical shift tensors for organic potassium complexes and diatomic molecules.

    PubMed

    Lee, Philip K; Chapman, Rebecca P; Zhang, Lei; Hu, Jiaxin; Barbour, Leonard J; Elliott, Elizabeth K; Gokel, George W; Bryce, David L

    2007-12-20

    Solid-state potassium-39 NMR spectra of two potassium complexes of crown-ether-based organic ligands (1.KI and 2) have been acquired at 11.75 and 21.1 T and interpreted to provide information on the 39K quadrupolar and chemical shift tensors. The analyses reveal a large potassium chemical shift tensor span of 75+/-20 ppm for 1.KI. This appears to be the first such measurement for potassium in an organic complex, thereby suggesting the utility of potassium chemical shift tensors for characterizing organic and biomolecular K+ binding environments. Compound 2 exhibits a cation-pi interaction between K+ and a phenyl group, and therefore, the 39K NMR tensors obtained for this compound must be partly representative of this interaction. Analyses of potassium-39 spin-rotation data for gaseous 39K19F and 39K35Cl available from molecular beam experiments performed by Cederberg and co-workers reveal the largest potassium CS tensor spans known to date, 84.39 and 141 ppm, respectively. Collectively, the results obtained highlight the potential of ultrahigh-field potassium-39 solid-state NMR spectroscopy and, in particular, the wide range of the anisotropy of the potassium CS tensor when organic and diatomic systems are considered. PMID:18020321

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    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 7Li+, 23Na+, 25Mg2+, 35Cl-, 39K+, or 133Cs+. 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. Optical limiting based on multiphoton processes in carbon nanostructures and heterocyclic quadrupolar molecules

    NASA Astrophysics Data System (ADS)

    Signorini, Raffaella; Pedron, D.; Ferrante, C.; Bozio, Renato; Brusatin, Giovanna; Innocenzi, Plinio; Della Negra, F.; Maggini, Michele; Abbotto, Alessandro; Beverina, L.; Pagani, Giorgio A.

    2003-02-01

    A novel scheme for implementing the joint exploitation of different, somehow complementary mechanisms of nonlinear transmission in an optical limiting device is proposed. As active materials we have chosen the fullerene derivative FULP, as a reverse saturable absorber, and a new heterocyclic quadrupolar dye, PEPEP, with highly efficient multiphoton absorption for nanosecond pulses. The nonlinear absorption properties of PEPEP in solution are extensively investigated for both femtosecond and nanosecond pulses. When Z-scan experiments are performed with nanosecond pulses, much larger effective cross sections are measured than with femtosecond pulses and with remarkably different wavelength dispersion. This is interpreted as due to two-photon absorption followed by one-photon absorption from the excited state. Chemically modified nonlinear molecules are incorporated in a hybrid organic-inorganic sol-gel matrix. Sufficiently high concentrations are achieved to allow the assembling of thin sol-gel disks into a "tandem" limiter with a total thickness smaller than the Rayleigh range of the focused laser beam. Preliminary testing of our limiter is reported and shows encouraging results. The resistance of the FULP-doped sol-gel glass to laser damage is substantially improved and the nonlinear attenuation at high pulse energies is enhanced.

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

    PubMed

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

    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 (7)Li(+), (23)Na(+), (25)Mg(2+), (35)Cl(-), (39)K(+), or (133)Cs(+). 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. PMID:26590539

  15. Magnetic Orders and Fluctuations in the Dipolar Pyrochlore Antiferromagnet

    NASA Astrophysics Data System (ADS)

    Cepas, Olivier; Shastry, B. Sriram

    2005-03-01

    While the classical Heisenberg antiferromagnet on the pyrochlore lattice does not order, we will discuss, from a theoretical standpoint, possible magnetic phases induced by the dipole-dipole interactions. Such interactions play a role in systems such as Gd2Ti2O7 or Gd2Sn2O7 in stabilizing exotic forms of magnetic order, a subject of current debate. We will also argue that the external magnetic field induces multiple transitions, one of which is associated with no obvious broken symmetry, but can be characterized by a disorder parameter. Finally, Monte-Carlo simulations and Landau-Ginzburg expansion show that the dipolar Heisenberg model exhibits a fluctuation-induced first-order transition, thanks to the frustration and a continuous set of soft modes.

  16. 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.

  17. 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

  18. Two-Photon Absorption Properties of Proquinoidal D-A-D and A-D-A Quadrupolar Chromophores

    PubMed Central

    Susumu, Kimihiro; Fisher, Jonathan A. N.; Zheng, Jieru

    2011-01-01

    We report the synthesis, one- and two-photon absorption spectroscopy, fluorescence, and electrochemical properties of a series of quadrupolar molecules that feature proquinoidal π-aromatic acceptors. These quadrupolar molecules possess either donor-acceptor-donor (D–A–D) or acceptor-donor-acceptor (A–D–A) electronic motifs, and feature 4-N,N-dihexylaminophenyl, 4-dodecyloxyphenyl, 4-(N,N-dihexylamino)benzo[c][1,2,5]thiadiazolyl or 2,5-dioctyloxyphenyl electron donor moieties and benzo[c][1,2,5]thiadiazole (BTD) or 6,7-bis(3’,7’-dimethyloctyl)[1,2,5]thiadiazolo[3,4-g]quinoxaline (TDQ) electron acceptor units. These conjugated structures are highly emissive in nonpolar solvents and exhibit large spectral red-shifts of their respective lowest energy absorption bands relative to analogous reference compounds that incorporate phenylene components in place of BTD and TDQ moieties. BTD-based D-A-D and A-D-A chromophores exhibit increasing fluorescence emission red-shifts, and a concomitant decrease of the fluorescence quantum yield (Φf) with increasing solvent polarity; these data indicate that electronic excitation augments benzothiadiazole electron density via an internal charge transfer mechanism. The BTD- and TDQ-containing structures exhibit blue-shifted two-photon absorption (TPA) spectra relative to their corresponding one-photon absorption (OPA) spectra, and display high TPA cross-sections (>100 GM) within these spectral windows. D-A-D and A-D-A structures that feature more extensive conjugation within this series of compounds exhibit larger TPA cross-sections consistent with computational simulation. Factors governing TPA properties of these quadrupolar chromophores are discussed within the context of a three-state model. PMID:21568299

  19. The synthesis and single and two-photon excited fluorescence of a new quasi-quadrupolar organoborane compound

    NASA Astrophysics Data System (ADS)

    Chen, Ying; Cao, Duxia; Wang, Shasha; Zhang, Changqiao; Liu, Zhiqiang

    2010-04-01

    A new acceptor-π-acceptor quadrupolar compound with a dimesitylboryl as acceptor and 2,7-dithienylfluorene as the conjugated bridge has been synthesized using the Suzuki-Miyaura coupling reaction. Its single and two-photon related photo-physical properties were experimentally examined. The combination of a large two-photon cross-section ( δ = 1150 GM at 730 nm in hexane), high emission quantum yield ( Ф = 0.81 in hexane) and a strong binding constant with fluoride anions ( K1 = 3.0 × 10 5 mol -1 L) make this compound attractive for application as a two-photon excited fluorescent chemosensor for fluoride anions.

  20. 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.

  1. 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.

  2. Local spin-density-wave order inside vortex cores in multiband superconductors

    NASA Astrophysics Data System (ADS)

    Mishra, Vivek; Koshelev, Alexei E.

    2015-08-01

    Coexistence of antiferromagnetic order with superconductivity in many families of newly discovered iron-based superconductors has renewed interest to this old problem. Due to competition between the two types of order, one can expect appearance of the antiferromagnetism inside the cores of the vortices generated by the external magnetic field. The structure of a vortex in type II superconductors holds significant importance from the theoretical and the application points of view. Here we consider the internal vortex structure in a two-band s± superconductor near a spin-density-wave instability. We treat the problem in a completely self-consistent manner within the quasiclassical Eilenberger formalism. We study the structure of the s± superconducting order and magnetic field-induced spin-density-wave order near an isolated vortex. We examine the effect of this spin-density-wave state inside the vortex cores on the local density of states.

  3. Non-Spherical Source-Surface Model of the Corona and Heliosphere for a Quadrupolar Main Field of the Sun

    NASA Astrophysics Data System (ADS)

    Schulz, M.

    2008-05-01

    Different methods of modeling the coronal and heliospheric magnetic field are conveniently visualized and intercompared by applying them to ideally axisymmetric field models. Thus, for example, a dipolar main B field with its moment parallel to the Sun's rotation axis leads to a flat heliospheric current sheet. More general solar main B fields (still axisymmetric about the solar rotation axis for simplicity) typically lead to cone-shaped current sheets beyond the source surface (and presumably also in MHD models). As in the dipolar case [Schulz et al., Solar Phys., 60, 83-104, 1978], such conical current sheets can be made realistically thin by taking the source surface to be non-spherical in a way that reflects the underlying structure of the Sun's main B field. A source surface that seems to work well in this respect [Schulz, Ann. Geophysicae, 15, 1379-1387, 1997] is a surface of constant F = (1/r)kB, where B is the scalar strength of the Sun's main magnetic field and k (~ 1.4) is a shape parameter. This construction tends to flatten the source surface in regions where B is relatively weak. Thus, for example, the source surface for a dipolar B field is shaped somewhat like a Rugby football, whereas the source surface for an axisymmetric quadrupolar B field is similarly elongated but somewhat flattened (as if stuffed into a pair of co-axial cones) at mid-latitudes. A linear combination of co-axial dipolar and quadrupolar B fields generates a somewhat apple-shaped source surface. If the region surrounded by the source surface is regarded as current-free, then the source surface itself should be (as nearly as possible) an equipotential surface for the corresponding magnetic scalar potential (expanded, for example, in spherical harmonics). More generally, the mean-square tangential component of the coronal magnetic field over the source surface should be minimized with respect to any adjustable parameters of the field model. The solar wind should then flow not quite radially, but rather in a straight line along the outward normal to the source surface, and the heliospheric B field should follow a corresponding generalization of Parker's spiral [Levine et al., Solar Phys., 77, 363-392, 1982]. In this work the above program is implemented for a Sun with an axisymmetric but purely quadrupolar main magnetic field. Two heliospheric current sheets emanate from circular neutral lines at mid-latitudes on the corresponding source surface. However, because the source surface is relatively flattened in regions where these neutral lines appear, the radial component of the heliospheric B field at r ~ 1 AU and beyond is much more nearly latitude-independent in absolute value than one would expect from a model based on a spherical source surface.

  4. Relaxation Effects in a System of a Spin-1solar2 Nucleus Coupled to a Quadrupolar Spin Subjected to RF Irradiation: Evaluation of Broadband Decoupling Schemes

    NASA Astrophysics Data System (ADS)

    Smith, Scott A.; Murali, Nagarajan

    1999-01-01

    We have investigated the suitability and performance of various decoupling methods on systems in which an observed spin-1/2 nucleusI(13C or15N) is scalar-coupled to a quadrupolar spinS(2H). Simulations and experiments have been conducted by varying the strength of the irradiating radiofrequency (RF) field, RF offset, relaxation times, and decoupling schemes applied in the vicinity of theS-spin resonance. TheT1relaxation of the quadrupolar spin has previously been shown to influence the efficiency of continuous wave (CW) decoupling applied on resonance in such spin systems. Similarly, the performance of broadband decoupling sequences should also be affected by relaxation. However, virtually all of the more commonly used broadband decoupling schemes have been developed without consideration of relaxation effects. As a consequence, it is not obvious how one selects a suitable sequence for decoupling quadrupolar nuclei with exotic relaxation behavior. Herein we demonstrate that, despite its simplicity, WALTZ-16 decoupling is relatively robust under a wide range of conditions. In these systems it performs as well as the more recently developed decoupling schemes for wide bandwidth applications such as GARP-1 and CHIRP-95. It is suggested that in macromolecular motional regimes, broadband deuterium decoupling can be achieved with relatively low RF amplitudes (500-700 Hz) using WALTZ-16 multiple pulse decoupling.

  5. 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.

  6. Optimized excitation pulses for the acquisition of static NMR powder patterns from half-integer quadrupolar nuclei.

    PubMed

    O'Dell, Luke A; Harris, Kristopher J; Schurko, Robert W

    2010-03-01

    Various amplitude- and phase-modulated excitation pulses for the observation of static NMR powder patterns from half-integer quadrupolar nuclei have been generated using the optimal control routines implemented in SIMPSON 2.0. Such pulses are capable of both excitation of the central transition and signal enhancement by population transfer from the satellites. Enhancements in excess of 100% have been achieved for the central transition of the spin-3/2 (87)Rb nucleus compared with a selective pi/2 pulse. These pulses are shown to be relatively insensitive to changes in RF power and transmitter offsets, and can achieve a more uniform signal enhancement than double-frequency sweeps (DFS), resulting in more accurate spectral lineshapes. We also investigate the possibility of "calibration-free" optimized pulses for general use on half-integer quadrupoles with unknown interaction parameters. Such pulses could prove extremely useful for studying low abundance or insensitive nuclei for which experimental optimization of the DFS scheme may be difficult. We demonstrate that a pulse optimized for an arbitrary spin-3/2 system can function well on multiple samples, and can also excite the central transition of higher spin numbers, albeit with a smaller enhancement. The mechanism by which these optimized pulses achieve the signal enhancement is highly complex and, unlike DFS, involves a non-linear excitation of the satellite transition manifold, as well as the generation and manipulation of significant multiple-quantum coherences. PMID:20060763

  7. 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.

  8. 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.

  9. 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.

  10. {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.

  11. 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.

  12. 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.; Bhmer, 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.

  13. "EASY: A simple tool for simultaneously removing background, deadtime and acoustic ringing in quantitative NMR spectroscopy. Part II: Improved ringing suppression, application to quadrupolar nuclei, cross polarisation and 2D NMR".

    PubMed

    Jaeger, Christian; Hemmann, Felix

    2014-01-01

    A simple experiment for Elimination of Artifacts in NMR SpectroscopY (EASY) was introduced in Part I, and it was shown that NMR probe background signals, spectral distortions due to deadtime effects, and acoustic ringing can be eliminated simultaneously from solid-state NMR spectra. In this Part II, it is shown that acoustic ringing suppression can be improved up to one order of magnitude compared to the original EASY pulse sequence by inserting a delay τ between the two data acquisition scans of the EASY pulse sequence. The achievable ringing suppression depends on the length of this delay and is limited by the spin-lattice relaxation time T1. Furthermore, EASY is considered in conjunction with NMR of quadrupolar nuclei. For strong second-order broadening, EASY can be used to acquire either pure central transition MAS patterns or pure satellite transition NMR spectra. Two further modifications to EASY are introduced. One concerns improved ringing artifact suppression in experiments in which the central transition NMR signal is amplified by Rotor Assisted Population Transfer (RAPT). The second EASY modification enables the acquisition of quantitative NMR spectra if signals with different quadrupole coupling constants are present. In addition, acoustic ringing and (11)B stator signals are removed. Finally, it is demonstrated that the basic idea of EASY for removing ringing artifacts can be realized for heteronuclear one-dimensional and hetero- and homo-nuclear multi-dimensional NMR experiments using extended phase cycling. (15)N{(1)H} CPMAS and (15)N 2D Exchange NMR spectroscopy are considered as examples. PMID:25200102

  14. Optimal nuclear magnetic resonance excitation schemes for the central transition of a spin 3/2 in the presence of residual quadrupolar coupling.

    PubMed

    Lee, Jae-Seung; Regatte, Ravinder R; Jerschow, Alexej

    2008-12-14

    Optimal control theory is applied for enhancing the intensity of the central peak of a spin 3/2 signal in the presence of a residual quadrupolar coupling. While a maximum enhancement is always possible in the regime omega(rf) < omega(Q) via the use of modulated and shaped pulses, the intermediate rf-power regime omega(rf)-omega(Q) does not admit simple solutions based on intuition. In this work we present optimized shaped pulses that have been derived using an optimization algorithm based on optimal control and test these with (23)Na NMR in this regime. In addition to enhancing the intensity of the central transition signal, the satellite peaks can be effectively suppressed, which is a useful feature for the implementation in (23)Na imaging sequences. PMID:19071931

  15. 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.

  16. 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.

  17. 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

  18. Magnetic field-induced self-assembly of iron oxide nanocubes.

    PubMed

    Singh, Gurvinder; Chan, Henry; Udayabhaskararao, T; Gelman, Elijah; Peddis, Davide; Baskin, Artem; Leitus, Gregory; Král, Petr; Klajn, Rafal

    2015-01-01

    Self-assembly of inorganic nanoparticles has been studied extensively for particles having different sizes and compositions. However, relatively little attention has been devoted to how the shape and surface chemistry of magnetic nanoparticles affects their self-assembly properties. Here, we undertook a combined experiment-theory study aimed at better understanding of the self-assembly of cubic magnetite (Fe3O4) particles. We demonstrated that, depending on the experimental parameters, such as the direction of the magnetic field and nanoparticle density, a variety of superstructures can be obtained, including one-dimensional filaments and helices, as well as C-shaped assemblies described here for the first time. Furthermore, we functionalized the surfaces of the magnetic nanocubes with light-sensitive ligands. Using these modified nanoparticles, we were able to achieve orthogonal control of self-assembly using a magnetic field and light. PMID:25920522

  19. An Experimental Determination of Static Magnetic Fields Induced Noise in Living Systems

    NASA Astrophysics Data System (ADS)

    Brady, Megan; Laramee, Craig

    2013-03-01

    Living systems are constantly exposed to static magnetic fields (SMFs) from both natural and man-made sources. Exposures vary in dose and duration ranging from geomagnetic (~50 ?T) to residential and industrial (~10s of mT) fields. Efforts to characterize responses to SMFs have yielded conflicting results, showing a dependence on experimental variables used. Here we argue that low to moderate SMF exposure is a sub-threshold perturbation operating below thermal noise, and assays that evaluate statistical characteristics of a single cell may identify responses not consistently found by population averaging approaches. Recent studies of gene expression show that it is a stochastic process capable of producing bursting dynamics. Moreover, theoretical and experimental methods have also been developed to allow quantitative estimates of the associated biophysical parameters. These developments provide a new way to assess responses of living systems to SMFs. In this work, we report on our efforts to use single molecule fluorescence in situ hybridization to assess responses of NIH-3T3 cells to SMF exposure at flux densities ranging from 1 to 440 mT for 48 hours. Results will contribute to determining mechanisms by which SMF exposure influences gene expression.

  20. 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

  1. Magnetic field induced rest potential shift of metallic electrodes in nitric acid solution

    NASA Astrophysics Data System (ADS)

    Rhen, F. M. F.; Dunne, P.; Coey, J. M. D.

    2006-12-01

    We have investigated the field-induced rest potential shift of Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Bi, and stainless steel in nitric acid solution. Anodic rest potential shifts of up to 4 mV, 10 mV, 35 mV and 2.4 mV were observed for Mn, Zn, Fe and Ni, respectively, with an applied field of 1.5 T, whereas no shift was observed for Cr, Cu, Sn, Bi, or stainless steel. The absence of a field-induced rest potential shift for the latter metals is associated with passivation of the electrode. The magnetic driving force responsible for field-induced rest potential shift is the Lorentz force, which enhances the corrosion currents through magnetically-induced stirring on a ten micron length scale. Tables 1, Figs 3, Refs 11.

  2. Magnetic field induced by the carbon nanotubes current by magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Tsubaki, Kotaro; Yamaguchi, Hiroshi

    2008-04-01

    Recently carbon nanotubes (CNTs) are reported to be able to generate large magnetic field because of their nanometer-size-diameter [K. Tsubaki, H. Yamaguchi, J. Phys. C 38 (2006) 49]. The magnetic fields around CNTs current path are investigated by magnetic force microscopy (MFM). Under the consideration of the magnetic properties of magnetically coated tip of MFM, tip heights, current directions, and background magnetic field, etc., the magnetic field distribution are analyzed. The distribution of the magnetic field generated by the CNTs current is found to be asymmetric, and its distribution anomaly is found to be a kind of hysteresis effect of the MFM cantilever materials.

  3. 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

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

    NASA Astrophysics Data System (ADS)

    Yang, Xi; Beckwith, Andrew W.; Miller, John H., Jr.; Wood, Lowell T.

    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 schizosacchraoymces pombe (fission yeast) cells induced by magnetic fields, as observed using a phase sensitive projection image technique. Unlike electric fields, magnetic fields only act on moving charges. The observed behavior is 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 - optical response from fission yeast cells.

  5. 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.

  6. 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.

  7. 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.

  8. Dynamo magnetic field-induced angular momentum transport in protostellar nebulae - The 'minimum mass' protosolar nebula

    NASA Technical Reports Server (NTRS)

    Stepinski, T. F.; Levy, E. H.

    1990-01-01

    Magnetic torques can produce angular momentum redistribution in protostellar nebulas. Dynamo magnetic fields can be generated in differentially rotating and turbulent nebulas and can be the source of magnetic torques that transfer angular momentum from a protostar to a disk, as well as redistribute angular momentum within a disk. A magnetic field strength of 100-1000 G is needed to transport the major part of a protostar's angular momentum into a surrounding disk in a time characteristic of star formation, thus allowing formation of a solar-system size protoplanetary nebula in the usual 'minimum-mass' model of the protosolar nebula. This paper examines the possibility that a dynamo magnetic field could have induced the needed angular momentum transport from the proto-Sun to the protoplanetary nebula.

  9. 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

  10. Identification of superconducting phases in ceramic particles by magnetic field induced forces using a magnetized wire

    NASA Astrophysics Data System (ADS)

    Pérez, Daniel; Hulliger, Jürg

    2010-06-01

    A new equipment for minority phase analysis of superconducting (SC) phases within chemically inhomogeneous ceramic grains using a high gradient magnetic field or field induced effect of torque is presented. Single grains down to 20 μm are either captured by a magnetized iron wire or identified because of their torque movement in a pulsed magnetic field. An assembly of many hundreds of grains can be investigated for minor quantities of SC phases from 80 K up to room temperature. A maximum field of up to 100-140 mT allows us to reliably identify SC grains and evaluate their SC critical temperatures Tc. Localization of SC grains allows us to extract them for further analysis. Experiments with YBa2Cu3O2-δ grains demonstrated that Tc values evaluated in such a way are rather close to those, which are determined by magnetization measurements.

  11. Exposure to a 50-Hz magnetic field induced ceramide generation in cultured cells.

    PubMed

    Qiu, Liping; Feng, Baihuan; Ni, Zuowei; Wu, Xiaodan; Sun, Wenjun

    2016-04-01

    Purpose To investigate the effects of a 50-Hz magnetic field (MF) exposure on ceramide metabolism, as well as the cascade downstream signaling pathways in human amniotic (FL) cells. Materials and methods FL cells were exposed to MF at 0.4 mT for different durations (from 5-60 min). The ceramides levels were analyzed with high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The activity of cathepsin D was assayed using a fluorometric assay kit, and the activity of protein phosphatase 2A (PP2A) was examined by Western blotting. After exposing to MF at 0.4 mT for 60 min with sequential culture for different durations (0, 3, 6, 12 or 36 h), the rate of cell apoptosis was assessed by flow cytometry. Results Exposing cells to MF at 0.4 mT for different durations caused a significant increase in ceramide production via de novo synthesis and hydrolysis of sphingomyelin (SM), and the effect was different according to the exposure time. However, no significant change in cell apoptosis was detected after MF exposure for 60 min with sequentially culturing for up to 36 h. In addition, increase in ceramide did not activate its downstream signal molecules, cathepsin D and PP2A, which are usually closely related to apoptosis of cells. Conclusions Exposure to a 50-Hz MF could raise ceramide levels but had no significant effect on apoptosis in cultured cells. PMID:26887861

  12. Phonon spectrum of the QCD vacuum in a magnetic-field-induced superconducting phase

    NASA Astrophysics Data System (ADS)

    Chernodub, M. N.; Van Doorsselaere, Jos; Verschelde, Henri

    2014-05-01

    In the background of a sufficiently strong magnetic field the vacuum was suggested to become an ideal electric conductor (highly anisotropic superconductor) due to an interplay between the strong and electromagnetic forces. The superconducting ground state resembles an Abrikosov lattice state in an ordinary type-II superconductor: it is an inhomogeneous structure made of a (charged vector) quark-antiquark condensate pierced by vortices. In this paper the acoustic (phonon) vibrational modes of the vortex lattice are studied at zero temperature. Using an effective model based on a vector meson dominance, we show that in the infrared limit the longitudinal (transverse) acoustic vibrations of the vortex lattice possess a linear (quadratic) dispersion relation corresponding to type-I (type-II) Nambu-Goldstone modes.

  13. Measurements of the magnetic field induced by a turbulent flow of liquid metal

    SciTech Connect

    Nornberg, M.D.; Spence, E.J.; Kendrick, R.D.; Jacobson, C.M.; Forest, C.B.

    2006-05-15

    Initial results from the Madison Dynamo Experiment provide details of the inductive response of a turbulent flow of liquid sodium to an applied magnetic field. The magnetic field structure is reconstructed from both internal and external measurements. A mean toroidal magnetic field is induced by the flow when an axial field is applied, thereby demonstrating the omega effect. Poloidal magnetic flux is expelled from the fluid by the poloidal flow. Small-scale magnetic field structures are generated by turbulence in the flow. The resulting magnetic power spectrum exhibits a power-law scaling consistent with the equipartition of the magnetic field with a turbulent velocity field. The magnetic power spectrum has an apparent knee at the resistive dissipation scale. Large-scale eddies in the flow cause significant changes to the instantaneous flow profile resulting in intermittent bursts of nonaxisymmetric magnetic fields, demonstrating that the transition to a dynamo is not smooth for a turbulent flow.

  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 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

  16. Pulsed magnetic field induced fast drug release from magneto liposomes via ultrasound generation.

    PubMed

    Podaru, George; Ogden, Saralyn; Baxter, Amanda; Shrestha, Tej; Ren, Shenqiang; Thapa, Prem; Dani, Raj Kumar; Wang, Hongwang; Basel, Matthew T; Prakash, Punit; Bossmann, Stefan H; Chikan, Viktor

    2014-10-01

    Fast drug delivery is very important to utilize drug molecules that are short-lived under physiological conditions. Techniques that can release model molecules under physiological conditions could play an important role to discover the pharmacokinetics of short-lived substances in the body. Here an experimental method is developed for the fast release of the liposomes' payload without a significant increase in (local) temperatures. This goal is achieved by using short magnetic pulses to disrupt the lipid bilayer of liposomes loaded with magnetic nanoparticles. The drug release has been tested by two independent assays. The first assay relies on the AC impedance measurements of MgSO4 released from the magnetic liposomes. The second standard release assay is based on the increase of the fluorescence signal from 5(6)-carboxyfluorescein dye when the dye is released from the magneto liposomes. The efficiency of drug release ranges from a few percent to up to 40% in the case of the MgSO4. The experiments also indicate that the magnetic nanoparticles generate ultrasound, which is assumed to have a role in the release of the model drugs from the magneto liposomes. PMID:25110807

  17. 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.

  18. 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

  19. 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.

  20. Extremely low-frequency magnetic field induces manganese accumulation in brain, kidney and liver of rats.

    PubMed

    Çelik, Mustafa Salih; Güven, Kemal; Akpolat, Veysi; Akdağ, Mehmet Zulkuf; Nazıroğlu, Mustafa; Gül-Güven, Reyhan; Çelik, M Yusuf; Erdoğan, Sait

    2015-06-01

    The aim of the present study was to determine the effects of extremely low-frequency magnetic field (ELF-MF) on accumulation of manganese (Mn) in the kidney, liver and brain of rats. A total of 40 rats were randomly divided into eight groups. Four control groups received 0, 3.75, 15 and 60 mg Mn per kg body weight orally every 2 days for 45 days, respectively. The remaining four groups received same concentrations of Mn and were also exposed to ELF-MF (1.5 mT; 50 Hz) for 4 h for 5 days a week during 45 days. Following the last exposure, kidney, liver and brain were taken from all rats and they were analyzed for Mn accumulation levels using an inductively coupled plasma-optical emission spectrometer. In result of the current study, we observed that Mn levels in brain, kidney and liver were higher in Mn groups than in control groups. Mn levels in brain, kidney and liver were also higher in Mn plus ELF-MF groups than in Mn groups. In conclusion, result of the current study showed that the ELF-MF induced manganese accumulation in kidney, liver and brain of rats. PMID:23448860

  1. 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.

  2. Magnetic-field-induced charge redistribution in disordered graphene double quantum dots

    NASA Astrophysics Data System (ADS)

    Chiu, K. L.; Connolly, M. R.; Cresti, A.; Griffiths, J. P.; Jones, G. A. C.; Smith, C. G.

    2015-10-01

    We have studied the transport properties of a large graphene double quantum dot under the influence of a background disorder potential and a magnetic field. At low temperatures, the evolution of the charge-stability diagram as a function of the B field is investigated up to 10 T. Our results indicate that the charging energy of the quantum dot is reduced, and hence the effective size of the dot increases at a high magnetic field. We provide an explanation of our results using a tight-binding model, which describes the charge redistribution in a disordered graphene quantum dot via the formation of Landau levels and edge states. Our model suggests that the tunnel barriers separating different electron/hole puddles in a dot become transparent at high B fields, resulting in the charge delocalization and reduced charging energy observed experimentally.

  3. 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

  4. 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

  5. Pressure-magnetic field induced phase transformation in Ni46Mn41In13 Heusler alloy

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The effect of hydrostatic pressure and magnetic field on the magnetic properties and phase transformation in Ni46Mn41In13 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 (As) is higher when larger field is applied, and (ii) field dependent shift of As 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. High magnetic field inducing magnetic transitions of Fe and Ni doped InO nanocubes

    NASA Astrophysics Data System (ADS)

    Sun, Qingbo; Zeng, Yu-Ping; Jiang, Dongliang

    2011-09-01

    Fe 3+ and Ni 2+ (5 at.%) doped In 2O 3 single-crystalline nanocubes showed distinctly different magnetic properties before and after 4T high magnetic field treatments. Fe 3+ doped In 2O 3 nanocrystals were transferred from paramagnetic to super-paramagnetic by treating them in high magnetic field while Ni 2+ doped In 2O 3 nanocubes obviously improved primary ferromagnetism. These special phenomena may open up a way to endow nanomaterials with novel and special functions. In addition, their magnetic properties were not caused by impurities or changes of morphologies and crystalline structures.

  7. Magnetic-field-induced enhancement of atomic stabilization in intense high-frequency laser fields

    NASA Astrophysics Data System (ADS)

    Simonsen, Aleksander Skjerlie; Frre, Morten

    2015-07-01

    The role of the magnetic-field component of the laser pulse on the phenomenon of atomic stabilization is investigated in an ab initio study. This is achieved by solving the time-dependent Schrdinger equation for the laser-atom interaction beyond the dipole approximation. The system under study is atomic hydrogen and the atom is assumed to be irradiated by an intense xuv laser light pulse of varying intensity and duration. We consider two different photon energies, ? ? =54 and 95 eV. The main finding is that there exists a range of laser pulse durations lasting for a few tens of field cycles where the atomic stabilization effect is enhanced due to the magnetic-field component. This is a rather surprising result that contradicts earlier statements made in the few-cycle pulse regime, where it has been shown that the magnetic field has a destructive effect in that the degree of stabilization is suppressed. It is further found that in the long-pulse limit the ionization probabilities obtained when illuminating the target with dipole and nondipole fields eventually coincide, meaning that the magnetic-field component of the laser field finally loses its significance in the context of atomic stabilization. It is also found that within the window of enhanced stabilization, the surplus population is distributed among excited bound states rather than in the initial ground state.

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

    PubMed

    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., (79)Br-(13)C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-(13)C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T(1) shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar (14)N adjacent to the (13)C 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 (13)C-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 (15)N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner. PMID:23262330

  9. 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.

  10. Determination of the 17O quadrupolar coupling constant and of the 13C shielding tensor anisotropy in solution for molecules containing a COOH group. NMR relaxation study and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Rubini, P.; Champmartin, D.; Assfeld, X.

    1998-02-01

    The shielding anisotropy (SA) of the 13C-nucleus Δ σ in COOH groups of some molecules could be deduced, in solution, from the measurements of the relaxation time T1 for different values of the magnetic field (contribution of the SA mechanism to the total relaxation rate) and from the determination of the reorientational correlation time of these species. Δ σ was determined in function of the solvent for benzoic acid, in function of pH for glycine and for free and bound (to Mg2+) ethylene diamine tetraacetate (EDTA) ion. For benzoic acid dissolved in benzene the results were compared to those obtained in an aqueous solution and in the solid state, and in diamine tetraacetate (EDTA) ion. For benzoic acid dissolved in benzene the results were compared to those obtained in an aqueous solution and in the solid state, and in order to try to explain the observed variations, theoretical calculations of Δ σ were performed. 17O NMR allowed us also to obtain the 17O quadrupolar coupling constant. A partir de l'étude de la variation du temps de relaxation T1 en fonction de la fréquence (contribution, à la relaxation totale, du mécanisme dû à l'anisotropie du tenseur d'écran) et de la connaissance du temps de corrélation de réorientation de ces espèces, nous avons pu atteindre la valeur de l'anisotropie du tenseur d'écran Δ σ du noyau 13C des groupes COOH de quelques molécules, en solution. Nous avons déterminé Δ σ pour une même molécule dans différentes conditions : en fonction du solvant (acide benzoïque ), du pH (glycine) et de la présence ou non d'un cation (éthylène diamine tétraacétate : EDTA). Pour l'acide benzoïque dissous dans le benzène nous avons comparé nos résultats à ceux obtenus en phase aqueuse et à l'état solide. Pour tenter d'expliquer les écarts observés, nous avons effectué des calculs théoriques de Δ σ. La RMN de l'oxygène-17 nous a permis également d'obtenir la constante de couplage quadripolaire de ce noyau.

  11. Non-linear Electric Conduction in Charge-ordered Insulating Manganites

    NASA Astrophysics Data System (ADS)

    Asamitsu, A.; Tomioka, Y.; Kuwahara, H.; Tokura, Y.

    1997-03-01

    Among various manganites, Pr_1-xCa_xMnO3 shows insulating behavior over the whole composition (x) range due to its narrow bandwidth of eg electron. The ground state of Pr_1-xCa_xMnO3 with x=0.3-0.5 is a charge-ordered (CO) antiferromagnetic insulator. It has been known, however, that this "charge crystal" can be easily melted into "charge liquid", namely a ferromagnetic metallic (FM) state, by applying a magnetic field of several Tesla, accompanying a metamagnetic phase transition as well as a drastic decrease of the resistivity by more than ten orders of magnitude. Considering the nature of this concomitant metamagnetic and insulator-to-metal transition, we may expect that forcedly moved carriers can revive ferromagnetic interaction and trigger the phase transition without a magnetic field. We report here that not only a magnetic field but also an electric field can give rise to the switching of resistive states in the manganites: The current-voltage (I-V) characteristic of the CO insulating manganites shows switching behaviors from high resistive to low resistive state, implying that a static high electric field or current flow can, like a magnetic field, induce collapse of the CO insulating state into a FM state.

  12. Dynamics of Spin I=3/2 under Spin-Locking Conditions in an Ordered Environment

    NASA Astrophysics Data System (ADS)

    van der Maarel, J. R. C.; 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.

  13. 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

  14. Quadrupole order in the frustrated pyrochlore magnet Tb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Takatsu, H.; Taniguchi, T.; Kittaka, S.; Sakakibara, T.; Kadowaki, H.

    2016-02-01

    We have studied the hidden long-range order (LRO) of the frustrated pyrochlore magnet Tb2Ti2O7 by means of specific-heat experiments and Monte-Carlo (MC) simulations, which has been discussed as the LRO of quadrupole moments inherent to the non-Kramers ion of Tb3+. We have found that the sharp specific-heat peak is collapsed into a broad hump by magnetic fields above 0.3 T for H//[001]. This result, qualitatively reproduced by MC simulations, suggests that a field-induced magnetic state overcomes the quadrupolar LRO state, as a similar case of a classical spin ice. The present results support the interpretation that Tb2+xTi2-xO7+y is a unique material in the boundary between the quadrupolar (x ⩾ xc = - 0.0025) and spin-liquid (x ⩽ xc) states, where the magnetic field along the [001] axis is a tuning parameter which induces the magnetic ordered state.

  15. 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…

  16. 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...

  17. INFLUENCE OF TEMPERATURE DURING THE ELECTRIC AND MAGNETIC FIELD-INDUCED ALTERATION OF CALCIUM RELEASE FROM BRAIN TISSUE, IN VITRO

    EPA Science Inventory

    The release of calcium ions from in vitro preparation of chicken brain-tissue has been used by several investigators to demonstrate the interaction of electric and magnetic (EM) fields with biological systems. or exposures with radiofrequency radiation amplitude modulated at extr...

  18. 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.

  19. Exposure to a 50-Hz magnetic field induced mitochondrial permeability transition through the ROS/GSK-3β signaling pathway.

    PubMed

    Feng, Baihuan; Qiu, Liping; Ye, Chunmei; Chen, Liangjing; Fu, Yiti; Sun, Wenjun

    2016-03-01

    Purpose To investigate the biological effects of a 50-Hz magnetic field (MF) on mitochondrial permeability. Materials and methods Human amniotic epithelial cells were exposed to MF (50 Hz, 0.4 mT) for different durations. Mitochondrial permeability, mitochondrial membrane potential (ΔΨm), cytochrome c (Cyt-c) release and the related mechanisms were explored. Results Exposure to the MF at 0.4 mT for 60 min transiently induced mitochondrial permeability transition (MPT) and Cyt-c release, although there was no significant effect on mitochondrial membrane potential (ΔΨm). Other than decreasing the total Bcl-2 associated X protein (Bax) level, MF exposure did not significantly affect the levels of Bax and B-cell lymphoma-2 (Bcl-2) in mitochondria. In addition, cells exposed to the MF showed increased intracellular reactive oxidative species (ROS) levels and glycogen synthase kinase-3β (GSK-3β) dephosphorylation at 9 serine residue (Ser(9)). Moreover, the MF-induced MPT was attenuated by ROS scavenger (N-acetyl-L-cysteine, NAC) or GSK-3β inhibitor, and NAC pretreatment prevented GSK-3β dephosphorylation (Ser(9)) caused by MF exposure. Conclusion MPT induced by MF exposure was mediated through the ROS/GSK-3β signaling pathway. PMID:26850078

  20. 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.

  1. A self-monitored theranostic platform based on nanoparticle hyperthermia therapy and alternating magnetic field induced thermoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Feng, Xiaohua; Gao, Fei; Zheng, Yuanjin

    2015-03-01

    Low frequency alternating magnetic field (AMF) had been advocated for thermoacoustic imaging to exploit their inherent deeper penetrations. AMF induced thermoacoustic imaging of magnetic nanoparticles is particularly appealing since the system setup is inherently compatible with nanoparticle hyperthermia therapy. More importantly, owing to the capacity of thermoacoustics for accurate temperature measurement, the integration of AMF induced thermoacoustic imaging into nanoparticle hyperthermia therapy will potentially enable a theranostic platform with imaging guidance and temperature monitoring capabilities. We present herein the AMF induced thermoacoustic process of magnetic nanoparticles experimentally and then investigate furthermore its utilization in temperature monitoring for the nanoparticle hyperthermia. To demonstrate the concept of an integrated theranostic system with minimal overhead, a single coil is used for both the hyperthermia heating and thermoacoustic imaging by interleaving the two processes in time domain. In thermoacoustic imaging mode, the power is set at the amplifier's maximum value whereas to avoid excess heating of the coil in hyperthermia-mode, the power is switched to a lower value and the coil is further cooled by static water. Phantom imaging results of the magnetic nanoparticles and the self temperature monitoring with sub-degree accuracy during hyperthermia process are demonstrated. These proof-of-concept experiments showcase the potential to integrate thermoacoustic imaging with nanoparticle hyperthermia system.

  2. 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.

  3. A variational approach towards the modeling of magnetic field-induced strains in magnetic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Wang, Jiong; Steinmann, Paul

    2012-06-01

    In this paper, the magneto-mechanical responses of a magnetic shape memory alloy (MSMA) sample are modeled through the variational approach. Motivated by the experimental results, a constitutive form for the effective magnetization vector is proposed. A (pseudo-)total energy functional for the whole magneto-mechanical system is then formulated, which takes into account the energy dissipations during the variant transformation process. By calculating the variations of the total energy functional with respect to the independent variables, the governing equation system for this model is derived, which is composed of the mechanical equilibrium equations, the magnetic field equations and some evolution laws for the internal variables. Under some simplifications, this model is used to study the magneto-mechanical responses of a MSMA sample under different magnetic and mechanical loading patterns. It can be seen that the results obtained in the model can capture the characteristic features of the field-strain, field-magnetization and stress-strain curves measured in the experiments.

  4. 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...

  5. The magnetic properties of well-aligned nickel nanochains synthesized by magnetic field-induced assembly approach

    NASA Astrophysics Data System (ADS)

    Kou, Zhaoxia; Liu, Er; Yue, Jinjin; Sui, Yunxia; Huang, Zhaocong; Zhang, Dong; Wang, Yukun; Zhai, Ya; Du, Jun; Zhai, Hongru

    2015-05-01

    Highly uniform one-dimensional Ni chains with controllable diameters and lengths have been synthesized at 70 °C by a hydrothermal process under a 0.35 T induced magnetic field. The diameter of the spheres in the magnetic Ni chains is adjusted from 80 nm to 1000 nm with the chain length changed from 1.2 μm to 50 μm by varying the concentration of ethylene glycol and potassium hydroxide in the solution. The Ni chains with different length-to-diameter aspect ratio show the different particle shape and interparticle spacing. Magnetic hysteresis loop measurements demonstrate a uniaxial magnetic anisotropy (UMA) on the coercivity (Hc), and saturation field (Hs). The ferromagnetic resonance (FMR) shows that the difference between demagnetizing fields in the direction of easy and hard increases with increasing the length-to-diameter aspect ratio of nanochains, which is close to then that in Hs. From FMR measurements and theoretical simulation, the difference of the demagnetizing field between the length and width directions of chains are obtained, which increases with increasing aspect ratio of chain. The value of the non-uniformity parameter c which describes the relative importance of the non-uniform demagnetizing effect is found to decrease as the aspect ratio increases.

  6. 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.

  7. 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.

  8. 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.

  9. The 4f multipole ordering effect on core-level spectroscopies of Ce intermetallics

    NASA Astrophysics Data System (ADS)

    Sasabe, Norimasa; Tonai, Hironori; Uozumi, Takayuki

    The 3 d transition metal compounds and 4 f rare earth compounds show attractive phenomena, such as superconductivity and Kondo effect, due to strong electron correlations among localized 3 d and 4 f electrons. Especially, multipole ordering of orbital and/or spin in 4 f and 5 fcompounds are attracting much attention these years. For example, CeB6 is known to show antiferro-quadrupolar (AFQ) ordering below 3.2K. X-ray core-level spectroscopy is an efficient technique to investigate the electronic states of strongly correlated systems. Recent years, experimental techniques have been rapidly developing and, especially, the progress in experimental resolution has enabled us to observe fine spectral features, which were not formerly observed. These advantages will enable us to observe spectral fine features related with the multipole ordering. In this study, we discuss multipole ordering effects on X-ray spectra for CeB6, especially paying attention on the polarization dependence. In order to simulate the electronic state of CeB6 with the multipole ordering, we use an impurity Anderson model including realistic valence structure and a simplified RKKY interaction.

  10. Experimental and theoretical studies of quadrupolar oligothiophene-cored chromophores containing dimesitylboryl moieties as π-accepting end-groups: syntheses, structures, fluorescence, and one- and two-photon absorption.

    PubMed

    Ji, Lei; Edkins, Robert M; Sewell, Laura J; Beeby, Andrew; Batsanov, Andrei S; Fucke, Katharina; Drafz, Martin; Howard, Judith A K; Moutounet, Odile; Ibersiene, Fatima; Boucekkine, Abdou; Furet, Eric; Liu, Zhiqiang; Halet, Jean-François; Katan, Claudine; Marder, Todd B

    2014-10-13

    Quadrupolar oligothiophene chromophores composed of four to five thiophene rings with two terminal (E)-dimesitylborylvinyl groups (4 V-5 V), and five thiophene rings with two terminal aryldimesitylboryl groups (5 B), as well as an analogue of 5 V with a central EDOT ring (5 VE), have been synthesized via Pd-catalyzed cross-coupling reactions in high yields (66-89%). Crystal structures of 4 V, 5 B, bithiophene 2 V, and five thiophene-derived intermediates are reported. Chromophores 4 V, 5 V, 5 B and 5 VE have photoluminescence quantum yields of 0.26-0.29, which are higher than those of the shorter analogues 1 V-3 V (0.01-0.20), and short fluorescence lifetimes (0.50-1.05 ns). Two-photon absorption (TPA) spectra have been measured for 2 V-5 V, 5 B and 5 VE in the range 750-920 nm. The measured TPA cross-sections for the series 2 V-5 V increase steadily with length up to a maximum of 1930 GM. We compare the TPA properties of 2 V-5 V with the related compounds 5 B and 5 VE, giving insight into the structure-property relationship for this class of chromophore. DFT and TD-DFT results, including calculated TPA spectra, complement the experimental findings and contribute to their interpretation. A comparison to other related thiophene and dimesitylboryl compounds indicates that our design strategy is promising for the synthesis of efficient dyes for two-photon-excited fluorescence applications. PMID:25168267

  11. 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.

  12. Spin fluctuations and hidden-order phases in Ce-based Kondo systems

    NASA Astrophysics Data System (ADS)

    Inosov, D. S.; Portnichenko, P. Y.; Cameron, A. S.; Paschen, S.; Prokofiev, A.; Friemel, G.; Jang, H.; Keimer, B.; Filipov, V. B.; Shitsevalova, N. Y.; Schneidewind, A.; Ivanov, A.; Ollivier, J.; Deen, P. P.; Strydom, A. M.

    Among heavy-fermion metals, both CeB6 and Ce3Pd20Si6 compounds exhibit a magnetically hidden ordered phase in their low-temperature phase diagram, which is attributed to the ordering of magnetic quadrupolar moments, known as the antiferroquadrupolar (AFQ) ordering. Using inelastic neutron scattering, we have investigated the spectrum of spin excitations in both systems. In the structurally simplest CeB6, it consists of several contributions including conventional spin waves that coexist with both ferro- and antiferromagnetic excitonic resonance-like modes. However, the structurally more complex Ce3Pd20Si6 possesses a much simpler magnetic excitation spectrum with only a single contribution peaked around the AFQ wave vector. It remains quasielastic in the absence of an external magnetic field, but then develops into dispersive magnon modes whose band width scales linearly with the applied field. Furthermore, neutron diffraction measurements on the same sample at sub-Kelvin temperatures revealed diffuse magnetic scattering that can be associated with the hidden order parameter. Supported by DFG Grant No. IN 209/3-1.

  13. A simple proof that third-order quadrupole perturbations of the NMR central transition of half-integral spin nuclei are zero

    NASA Astrophysics Data System (ADS)

    Bain, Alex D.

    2006-04-01

    It has been known for a long time that the third-order quadrupole corrections to transitions from mz = - n/2 to mz = + n/2 are zero in the NMR of half-integer nuclei. However, the derivation has relied on deriving the corrections to the energy levels through somewhat laborious calculations. Only when the transitions between the levels were calculated was it revealed that the corrections to the transition frequency were zero. In this paper, we use Liouville-space methods to work with the transitions directly. Application of a recently published [A.D. Bain, Exact calculation, using angular momentum, of combined Zeeman and quadrupolar interactions in NMR, Mol. Phys. 101 (2003) 3163-3175] selection rule for the quadrupole coupling leads to a very simple proof that third-order corrections to the central and other symmetrical transitions are zero. The simplicity of the proof suggests there is a fundamental symmetry involved.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Universal distribution of magnetic anisotropy of impurities in ordered and disordered nanograins

    NASA Astrophysics Data System (ADS)

    Szilva, A.; Balla, P.; Eriksson, O.; Zaránd, G.; Szunyogh, L.

    2015-04-01

    We examine the distribution of the magnetic anisotropy experienced by a magnetic impurity embedded in a metallic nanograin. As an example of a generic magnetic impurity with a partially filled d shell, we study the case of d1 impurities embedded into ordered and disordered Au nanograins, described in terms of a realistic band structure. Confinement of the electrons induces a magnetic anisotropy that is large, and can be characterized by five real parameters, coupling to the quadrupolar moments of the spin. In ordered (spherical) nanograins, these parameters exhibit symmetrical structures and reflect the symmetry of the underlying lattice, while for disordered grains they are randomly distributed and, for stronger disorder, their distribution is found to be characterized by random matrix theory. As a result, the probability of having small magnetic anisotropies KL is suppressed below a characteristic scale ΔE, which we predict to scale with the number of atoms N as ΔE˜1 /N3 /2 . This gives rise to anomalies in the specific heat and the susceptibility at temperatures T ˜ΔE and produces distinct structures in the magnetic excitation spectrum of the clusters that should be possible to detect experimentally.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Magnetic Field-Induced Phase Transition of Quantum Spin System Cu2Cl4ṡH8C4SO2

    NASA Astrophysics Data System (ADS)

    Fujisawa, Masashi; Tanaka, Hidekazu; Sakakibara, Toshiro

    2006-09-01

    The magnetic properties of Cu2Cl4ṡH8C4SO2 are described by an S = 1/2 double spin chain with strong exchange interactions along the leg direction. This system has a singlet ground state with an excitation gap of Δ/kB = 5.13 K. We have measured the magnetization and the specific heat of Cu2Cl4ṡH8C4SO2. The magnetic phase transition due to interchain interactions was observed for H > 4 T. Magnetic phase diagrams were obtained for H ∥ b- and c-axes. The phase boundaries for these two different field directions can be represented by the power law (g/2)[HN(T) - Hg] ∝ Tφ with (g/2)Hg = 3.83 T and φ = 1.98. The experimental exponent φ = 1.98 is somewhat larger than the value φBEC = 3/2 predicted by the magnon Bose-Einstein condensation theory.

  5. Magnetic Field-Induced Phase Transition in Quantum Spin System Cu_2Cl_4\\cdotH_8C_4SO_2

    NASA Astrophysics Data System (ADS)

    Fujisawa, M.; Tanaka, H.; Sakakibara, T.

    Cu_2Cl_4\\cdotH_8C_4SO_2 is an S = 1/2 double chain antiferromagnet, which has a singlet ground state with an excitation gap of Δ/kB = 5.13 K. The specific heat was measured in magnetic fields up to 9 T. The magnetic phase transition due to interchain interactions was observed for H ≳ 4 T. Magnetic phase diagram was obtained for H ∥ b- and c-axes. The phase boundaries for these two field directions coincide when normalized by the g-factor. The phase boundary can be represented by the power law (g/2)[HN(T)-Hg] ∝ Tφ with (g/2)Hg = 3.83 T and φ = 1.98.

  6. 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.

  7. Magnetic-Field-Induced Griffiths Phase versus Random-Field Criticality and Domain Wall Susceptibility of Fe0.47Zn0.53F2

    NASA Astrophysics Data System (ADS)

    Binek, Ch.; Kuttler, S.; Kleemann, W.

    1995-09-01

    The well-known peak of the parallel ac susceptibility arising below TN in Fe0.47Zn0.53F2 splits into a narrow critical peak at Tc\\(H\\) and a broad field-induced Griffiths phase shoulder peaking at Tp>Tc\\(H\\) in magnetic fields H>~1.6 MA /m. Random-field (RF) criticality with α~~0 and subsequent rounding due to RF trapping of thermal fluctuations are observed upon zero-field cooling as T-->T-c\\(H\\). The frozen domain state obtained after rapid field cooling reveals excess susceptibility Δχ'w~H2.6, owing to rough walls with thermally activated stiffness.

  8. Microwave spectroscopy evidence of superconducting pairing in the magnetic-field-induced metallic state of InO(x) films at zero temperature.

    PubMed

    Liu, Wei; Pan, LiDong; Wen, Jiajia; Kim, Minsoo; Sambandamurthy, G; Armitage, N P

    2013-08-01

    We investigate the field-tuned quantum phase transition in a 2D low-disorder amorphous InO(x) film in the frequency range of 0.05 to 16 GHz employing microwave spectroscopy. In the zero-temperature limit, the ac data are consistent with a scenario where this transition is from a superconductor to a metal instead of a direct transition to an insulator. The intervening metallic phase is unusual with a small but finite resistance that is much smaller than the normal state sheet resistance at the lowest measured temperatures. Moreover, it exhibits a superconducting response on short length and time scales while global superconductivity is destroyed. We present evidence that the true quantum critical point of this 2D superconductor metal transition is located at a field B(sm) far below the conventionally defined critical field B(cross) where different isotherms of magnetoresistance cross each other. The superfluid stiffness in the low-frequency limit and the superconducting fluctuation frequency from opposite sides of the transition both vanish at B≈B(sm). The lack of evidence for finite-frequency superfluid stiffness surviving B(cross) signifies that B(cross) is a crossover above which superconducting fluctuations make a vanishing contribution to dc and ac measurements. PMID:23971604

  9. Magnetic field-induced type I → type II transition in a semimagnetic {CdTe}/{Cd0.93Mn0.07Te} superlattice

    NASA Astrophysics Data System (ADS)

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

    Magneto-photoluminescence and photoluminescence excitation spectroscopy experiments are performed up to 5 Teslas at 1.7 K on a <111> grown CdTe/Cd 0.93Mn 0.07Te superlattice. The results are compared with calculations of the energy levels and of the exciton binding energies, including field-induced negative offsets. A type I → type II transition is evidenced near 2 Teslas and a value of 15-20% of the bandgap energy difference is deduced for the valence band offset.

  10. ASDC Order Tools

    Atmospheric Science Data Center

    2012-04-17

    ... ASDC Web Ordering Tools Java Tool Help HTML Tool Help These tools allow users to search our data holdings ... The ordering tool is available in both Java and HTML versions. Reverb Search Tool Reverb Tutorial ...

  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. 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.

  13. Contribution of higher order plasmonic modes on optical absorption enhancement in amorphous silicon thin films

    NASA Astrophysics Data System (ADS)

    Mandal, Aparajita; Chaudhuri, Partha

    2013-07-01

    For an array of regularly patterned interacting spherical Ag nano particles over an amorphous silicon (a-Si:H) layer of thickness 200 nm, we use Finite Difference Time Domain method for studying the plasmonic absorption enhancement within the a-Si:H layer over the visible range (400 nm-750 nm). The nano particle radius (R) has been varied from 100 nm to 200 nm and array period (D) from 320 nm to 500 nm satisfying the criteria 2Rorder plasmonic modes (mainly quadrupolar and octupolar) have significant contribution to the absorption enhancement within the a-Si:H layer. The role of the spectral overlap between different plasmonic modes has been described in controlling the absorption spectra for various configurations of R and D. It has been shown that a broad spectral absorption enhancement within the visible spectrum may be possible for a wide range of D variation from 320 nm to 500 nm using array of nano particles having R=140 nm. On the other hand, choosing a surface coverage factor of 19%, enhanced absorption within narrow wavelengths bands has been observed. The position of these narrow bands may be tuned by suitable choice of nano particle size. We propose these findings to proffer promising applications in solar cells as also in visible range photo detectors.

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

    PubMed Central

    Holt, Andrea; Rougier, La; Rat, Valrie; 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 toany transmembrane helical peptide. The influence of the experimental data set on the solution space is discussed, as are potential sources of error. PMID:20441750

  15. All-orders Skyrmions

    SciTech Connect

    Marleau, L. )

    1992-03-01

    We consider a special class of Skyrme-like Lagrangians which include higher-order terms in the derivatives of the pion field but leave the degree of the chiral angle equation at 2. Explicit Lagrangians are constructed up to order 24. They are found to be in agreement with a previous conjecture regarding the general form of the static energy density to all orders for the hedgehog solution. In addition, the static energy density gets zero contribution from Lagrangians of order 10, 14, 18, and 22, suggesting that this result extends to all order 4{ital k}+2 for {ital k}{ge}2. We then proceed to prove both conjectures.

  16. 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

  17. Characterizing limit order prices

    NASA Astrophysics Data System (ADS)

    Withanawasam, R. M.; Whigham, P. A.; Crack, Timothy Falcon

    2013-11-01

    A computational model of a limit order book is used to study the effect of different limit order distribution offsets. Reference prices such as same side/contra side best market prices and last traded price are considered in combination with different price offset distributions. We show that when characterizing limit order prices, varying the offset distribution only produces different behavior when the reference price is the contra side best price. Irrespective of the underlying mechanisms used in computing the limit order prices, the shape of the price graph and the behavior of the average order book profile distribution are strikingly similar in all the considered reference prices/offset distributions. This implies that existing averaging methods can cancel variabilities in limit order book shape/attributes and may be misleading.

  18. 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.

  19. 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.

  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. Intermolecular order in coals

    SciTech Connect

    Skripchenko, G.B.

    1984-01-01

    Questions of the molecular and supermolecular ordering of the structural units of the organic matter of coals are considered. The influence of the chemical structure of molecular clusters on the possibility of their dense packing in the coal structure has been shown. A hypothesis has been put forward concerning the heterogeneous process of crystallization during the metamorphism of coals. The influence of the texture and petrographic composition on the molecular and supermolecular ordering in coals is considered.

  2. 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.’

  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. 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…

  5. Keeping Order in Anaphase.

    PubMed

    Malumbres, Marcos

    2015-11-23

    The critical components of chromosome segregation machinery are well established, but how they orchestrate the relative order of events during mitosis remains unclear. Kamenz et al. (2015) now report in Molecular Cell quantitative data suggesting competing networks and adaptive thresholds in the control of mitotic exit by the anaphase-promoting complex. PMID:26609955

  6. Sympathy and Social Order

    ERIC Educational Resources Information Center

    Irwin, Kyle; McGrimmon, Tucker; Simpson, Brent

    2008-01-01

    Social order is possible only if individuals forgo the narrow pursuit of self-interest for the greater good. For over a century, social scientists have argued that sympathy mitigates self-interest and recent empirical work supports this claim. Much less is known about why actors experience sympathy in the first place, particularly in fleeting…

  7. Order Division Automated System.

    ERIC Educational Resources Information Center

    Kniemeyer, Justin M.; And Others

    This publication was prepared by the Order Division Automation Project staff to fulfill the Library of Congress' requirement to document all automation efforts. The report was originally intended for internal use only and not for distribution outside the Library. It is now felt that the library community at-large may have an interest in the…

  8. 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…

  9. 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...

  10. 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

  11. 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

  12. Order, topology and preference

    NASA Technical Reports Server (NTRS)

    Sertel, M. R.

    1971-01-01

    Some standard order-related and topological notions, facts, and methods are brought to bear on central topics in the theory of preference and the theory of optimization. Consequences of connectivity are considered, especially from the viewpoint of normally preordered spaces. Examples are given showing how the theory of preference, or utility theory, can be applied to social analysis.

  13. Sympathy and Social Order

    ERIC Educational Resources Information Center

    Irwin, Kyle; McGrimmon, Tucker; Simpson, Brent

    2008-01-01

    Social order is possible only if individuals forgo the narrow pursuit of self-interest for the greater good. For over a century, social scientists have argued that sympathy mitigates self-interest and recent empirical work supports this claim. Much less is known about why actors experience sympathy in the first place, particularly in fleeting

  14. 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…

  15. 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…

  16. 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...

  17. 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)

  18. Ordering Your Operations.

    ERIC Educational Resources Information Center

    Booth, Lesley R.

    1982-01-01

    Many children do not appear to see any need to worry about the conventions for ordering operations or using brackets in algebra problems, due to the "intuitive" mode of approach they use in mathematics. The need to teach pupils the necessity of such conventions is discussed. (MP)

  19. Second order gauge theory

    SciTech Connect

    Cuzinatto, R.R. . E-mail: rodrigo@ift.unesp.br; Melo, C.A.M. de . E-mail: cassius.anderson@gmail.com; Pompeia, P.J. . E-mail: pompeia@ift.unesp.br

    2007-05-15

    A gauge theory of second order in the derivatives of the auxiliary field is constructed following Utiyama's program. A novel field strength G = {partial_derivative}F + fAF arises besides the one of the first order treatment, F = {partial_derivative}A - {partial_derivative}A + fAA. The associated conserved current is obtained. It has a new feature: topological terms are determined from local invariance requirements. Podolsky Generalized Eletrodynamics is derived as a particular case in which the Lagrangian of the gauge field is L {sub P} {proportional_to} G {sup 2}. In this application the photon mass is estimated. The SU (N) infrared regime is analysed by means of Alekseev-Arbuzov-Baikov's Lagrangian.

  20. Mrs. Asuman's emergency order.

    PubMed

    1992-01-01

    The Family Planning Management Development Project presents a case scenario for family planning manager training and group discussion. The manager of a family planning clinic, Mrs. Asuman, notes that the demand for condoms has increased about 3-fold in the last 3 months. The Ministry of Health's condom promotional radio campaign, which began 2 months ago, is probably responsible for the increase. Clinic staff did not know about the campaign when they made their last order 2 months ago. The supplies of condoms are lower than the minimum level and the next routine ordering time is in another month. The supervising nurse comments that other clinics have the same problem, presumably due to the radio campaign. She inspects the storeroom, cartons of contraceptives and their expiration dates, and puts monthly tallies from the stock cards for each type of contraceptive on the Contraceptive Data Analysis Charts. This activity confirms the increase in demand for condoms. If the demand rate increases at the current rate, the clinic will be out of condoms in 2 weeks, the same amount of time it takes for an emergency order to arrive. Using the Max/Min System, and based on the demand in August, the supervising nurse and Mrs. Asuman calculate the average monthly consumption of condoms, which translates into a 4.1 months' supply. This should meet client demand until the next order arrives in February. Mrs. Asuman needs to closely monitor the number of condoms distributed for the next few months until demand stabilizes to determine whether the high demand for condoms continues at the high rate. The project presents questions on this case for group discussion. It also provides a case worksheet for this case study so family planning managers undergoing training can learn the Max/Min system. It includes sample worksheets of the Contraceptive Data Analysis Chart and an answer sheet. PMID:12319219

  1. Hybrid Computed Order Tracking

    NASA Astrophysics Data System (ADS)

    Bossley, K. M.; McKendrick, R. J.; Harris, C. J.; Mercer, C.

    1999-07-01

    Vibration analysis is an integral part of modern condition monitoring and fault diagnosis systems for rotating machinery. Orders (cycles per revolution) are used as a frequency base for this analysis, thus making speed-related vibrations easier to detect. Fundamental to the performance of such systems is the accuracy and reliability of the required synchronously sampled vibration data. In this paper, the accuracy of three different synchronous sampling schemes are studied: a traditional hardware solution, computed order tracking and a hybrid of the two. Run-ups and run-downs are of particular interest in condition monitoring systems as they highlight many shaft defects. Also, because of the sometimes rapid shaft speed changes, this is just where the traditional approaches to producing synchronous sampling are prone to producing erroneous results. The three methods are assessed on data produced from a simulation of the rundown of a gas turbine shaft, typical to those found in the power industry. The use of this simulation allows the true accuracy of the techniques to be accessed, and inadequacies of traditional methods are clearly highlighted. The different sampling schemes rely on various interpolation algorithms. The accuracy and reliability of these algorithms is fundamental to the performance of the different sampling schemes, and hence a survey of the state-of-the-art interpolation algorithms is presented. This ensures that the most appropriate algorithms are identified, and as a result the novel computed order tracking technique introduced in this paper is shown to produce superior results.

  2. Higher order Bezier circles

    NASA Technical Reports Server (NTRS)

    Chou, Jin

    1993-01-01

    Rational Bezier and B-spline representations of circles have been heavily publicized. However, all the literature assumes the rational Bezier segments in the homogeneous space are both planar and (equivalent to) quadratic. This creates the illusion that circles can only be achieved by planar and quadratic curves. Circles that are formed by higher order rational Bezier curves which are nonplanar in the homogeneous space are shown. The problem of whether it is possible to represent a complete circle with one Bezier curve is investigated. In addition, some other interesting properties of cubic Bezier arcs are discussed.

  3. 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.

  4. 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.

  5. Ordered photonic microstructures

    NASA Astrophysics Data System (ADS)

    Chen, Kevin Ming

    2001-09-01

    This thesis examines novel photonic materials systems possessing order in the atomic, microscopic, and macroscopic dimensional regimes. In the atomic order regime, a structure-property investigation is done for Er2O3 in which the first report of room temperature photoluminescence (PL) is provided. Thin films of the rare earth oxide were deposited via reactive sputtering of Er metal in an Ar/O2 ambient, and subsequently annealed to promote grain growth. Heat treatment consisting of a 650°C followed by 1000°C anneal produces maximum crystallinity as measured by glancing angle x-ray diffraction. These films show characteristic PL at λ = 1.54 μm. In the microscopic order regime, omnidirectional reflectors and thin film microcavities are demonstrated using sol-gel and solid-state materials. A first demonstration of omnidirectional reflectivity in sol-gel structures was accomplished using a dielectric stack consisting of 12 spin-on SiO 2/TiO2 quarterwave sol-gel films. Similarly, solid-state dielectric stacks consisting of 6 Si/SiO2 sputtered films were used to demonstrate the same principle. Microcavities were formed using solgel structures, producing a low quality factor Q = 35 due to limitations in film thickness control and lossy interfaces from stress-induced cracks. The high index contrast Si/SiO2 microcavities enabled Q ~ 1000 using 17 total layers following hydrogenation of dangling bonds within the amorphous Si films. Combining fabrication processes for the solid-state microcavity and Er2O3 films, a device was fabricated to demonstrate photoluminescence enhancement of an Er2O3 film embedded in a microcavity. The structure consisted of 3-bilayer mirrors on either side of an SiO2/Er2O3/SiO2 cavity. The Q ~ 300 was near the theoretical value for such a structure. At room temperature, PL of Er2O3 was enhanced by a factor of 1000 in the microcavity compared to a single thin film. In the macroscopic order regime, self-assembly of micron- sized SiO 2 and polystyrene latex colloidal particles into 2D crystals is presented. The colloidal assemblies offer a relatively easy processing route for fabrication of photonic bandgap structures. Large (>1 mm diameter) single crystal grains of colloids were formed using controlled evaporation and fluid flow techniques. A novel solution enabling post-processing of the fragile ordered assemblies is presented in which polyelectrolyte multilayers serve as adsorption platforms that anchor the colloidal assemblies. Tailorability of the polyelectrolyte surface properties (charge density, morphology) enables tuning of the colloid adsorption behavior. The polyelectrolyte surface affects colloid adsorption by influencing its surface diffusion. Observations of colloid surface diffusion were made using optical microscopy. Use of polyelectrolytes patterned via microcontact printing enables fabrication of colloid assemblies containing predesigned point and line defects. The patterned polyelectrolyte adsorption template allows placement of colloids in specific geometric arrangement, making possible the realization of sensors or functional photonic bandgap devices such as waveguides or photon traps. Three mechanisms were used to control adsorption: (1)pH of the colloid suspension, which determines the ionization of the uppermost surface of the polyelectrolyte multilayer; (2)ionic strength of the suspension, which determines the extent of charge screening about the colloid and polyelectrolyte; and (3)concentration of added surfactant, which causes charge screening and introduces hydrophobic interactions between the surfactant and polyelectrolyte. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253- 1690.)

  6. First order kaon condensate

    SciTech Connect

    Glendenning, N.K.; Schaffner-Bielich, J.; Schaffner-Bielich, J.

    1999-08-01

    First order Bose condensation in asymmetric nuclear matter and in neutron stars is studied, with particular reference to kaon condensation. We demonstrate explicitly why the Maxwell construction fails to assure equilibrium in multicomponent substances. Gibbs conditions and conservation laws require that for phase equilibrium, the charge density must have opposite sign in the two phases of isospin asymmetric nuclear matter. The mixed phase will therefore form a Coulomb lattice with the rare phase occupying lattice sites in the dominant phase. Moreover, the kaon condensed phase differs from the normal phase, not by the mere presence of kaons in the first, but also by a difference in the nucleon effective masses. The mixed phase region, which occupies a large radial extent amounting to some kilometers in our model neutron stars, is thus highly heterogeneous. It should be particularly interesting in connection with the pulsar glitch phenomenon as well as transport properties. {copyright} {ital 1999} {ital The American Physical Society}

  7. First order kaon condensate

    NASA Astrophysics Data System (ADS)

    Glendenning, Norman K.; Schaffner-Bielich, Jürgen

    1999-08-01

    First order Bose condensation in asymmetric nuclear matter and in neutron stars is studied, with particular reference to kaon condensation. We demonstrate explicitly why the Maxwell construction fails to assure equilibrium in multicomponent substances. Gibbs conditions and conservation laws require that for phase equilibrium, the charge density must have opposite sign in the two phases of isospin asymmetric nuclear matter. The mixed phase will therefore form a Coulomb lattice with the rare phase occupying lattice sites in the dominant phase. Moreover, the kaon condensed phase differs from the normal phase, not by the mere presence of kaons in the first, but also by a difference in the nucleon effective masses. The mixed phase region, which occupies a large radial extent amounting to some kilometers in our model neutron stars, is thus highly heterogeneous. It should be particularly interesting in connection with the pulsar glitch phenomenon as well as transport properties.

  8. 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:20398287

  9. 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

  10. 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:20398287

  11. 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

  12. Order in Spontaneous Behavior

    PubMed Central

    Maye, Alexander; Hsieh, Chih-hao; Sugihara, George; Brembs, Björn

    2007-01-01

    Brains are usually described as input/output systems: they transform sensory input into motor output. However, the motor output of brains (behavior) is notoriously variable, even under identical sensory conditions. The question of whether this behavioral variability merely reflects residual deviations due to extrinsic random noise in such otherwise deterministic systems or an intrinsic, adaptive indeterminacy trait is central for the basic understanding of brain function. Instead of random noise, we find a fractal order (resembling Lévy flights) in the temporal structure of spontaneous flight maneuvers in tethered Drosophila fruit flies. Lévy-like probabilistic behavior patterns are evolutionarily conserved, suggesting a general neural mechanism underlying spontaneous behavior. Drosophila can produce these patterns endogenously, without any external cues. The fly's behavior is controlled by brain circuits which operate as a nonlinear system with unstable dynamics far from equilibrium. These findings suggest that both general models of brain function and autonomous agents ought to include biologically relevant nonlinear, endogenous behavior-initiating mechanisms if they strive to realistically simulate biological brains or out-compete other agents. PMID:17505542

  13. Jaw and order.

    PubMed

    Mooshammer, Christine; Hoole, Philip; Geumann, Anja

    2007-01-01

    It is well-accepted that the jaw plays an active role in influencing vowel height. The general aim of the current study is to further investigate the extent to which the jaw is active in producing consonantal distinctions, with specific focus on coronal consonants. Therefore, tongue tip and jaw positions are compared for the German coronal consonants /s, f, t, d, n, l/, that is, consonants having the same active articulators (apical/laminal) but differing in manner of articulation. In order to test the stability of articulatory positions for each of these coronal consonants, a natural perturbation paradigm was introduced by recording two levels of vocal effort: comfortable, and loud without shouting. Tongue and jaw movements of five speakers of German were recorded by means of EMMA during /aCa/ sequences. By analyzing the tongue tip and jaw positions and their spatial variability we found that (1) the jaw's contribution to these consonants varies with manner of articulation, and (2) for all coronal consonants the positions are stable across loudness conditions except for those of the nasal. Results are discussed with respect to the tasks of the jaw, and the possible articulatory adjustments that may accompany louder speech. PMID:17702471

  14. The order Herpesvirales.

    PubMed

    Davison, Andrew J; Eberle, Richard; Ehlers, Bernhard; Hayward, Gary S; McGeoch, Duncan J; Minson, Anthony C; Pellett, Philip E; Roizman, Bernard; Studdert, Michael J; Thiry, Etienne

    2009-01-01

    The taxonomy of herpesviruses has been updated by the International Committee on Taxonomy of Viruses (ICTV). The former family Herpesviridae has been split into three families, which have been incorporated into the new order Herpesvirales. The revised family Herpesviridae retains the mammal, bird and reptile viruses, the new family Alloherpesviridae incorporates the fish and frog viruses, and the new family Malacoherpesviridae contains a bivalve virus. Three new genera have been created in the family Herpesviridae, namely Proboscivirus in the subfamily Betaherpesvirinae and Macavirus and Percavirus in the subfamily Gammaherpesvirinae. These genera have been formed by the transfer of species from established genera and the erection of new species, and other new species have been added to some of the established genera. In addition, the names of some nonhuman primate virus species have been changed. The family Alloherpesviridae has been populated by transfer of the genus Ictalurivirus and addition of the new species Cyprinid herpesvirus 3. The family Malacoherpesviridae incorporates the new genus Ostreavirus containing the new species Ostreid herpesvirus 1. PMID:19066710

  15. Order in dense hydrogen at low temperatures

    PubMed Central

    Edwards, B.; Ashcroft, N. W.

    2004-01-01

    By increase in density, impelled by pressure, the electronic energy bands in dense hydrogen attain significant widths. Nevertheless, arguments can be advanced suggesting that a physically consistent description of the general consequences of this electronic structure can still be constructed from interacting but state-dependent multipoles. These reflect, in fact self-consistently, a disorder-induced localization of electron states partially manifesting the effects of proton dynamics; they retain very considerable spatial inhomogeneity (as they certainly do in the molecular limit). This description, which is valid provided that an overall energy gap has not closed, leads at a mean-field level to the expected quadrupolar coupling, but also for certain structures to the eventual emergence of dipolar terms and their coupling when a state of broken charge symmetry is developed. A simple Hamiltonian incorporating these basic features then leads to a high-density, low-temperature phase diagram that appears to be in substantial agreement with experiment. In particular, it accounts for the fact that whereas the phase I–II phase boundary has a significant isotope dependence, the phase II–III boundary has very little. PMID:15028839

  16. Topology in Ordered Phases

    NASA Astrophysics Data System (ADS)

    Tanda, Satoshi; Matsuyama, Toyoki; Oda, Migaku; Asano, Yasuhiro; Yakubo, Kousuke

    2006-08-01

    I. Topology as universal concept. Optical vorticulture / M. V. Berry. On universality of mathematical structure in nature: topology / T. Matsuyama. Topology in physics / R. Jackiw. Isoholonomic problem and holonomic quantum computation / S. Tanimura -- II. Topological crystals. Topological crystals of NbSe[symbol] / S. Tanda ... [et al.]. Superconducting states on a Möbius strip / M. Hayashi ... [et al.]. Structure analyses of topological crystals using synchrotron radiation / Y. Nogami ... [et al.]. Transport measurement for topological charge density waves / T. Matsuura ... [et al.]. Theoretical study on Little-Parks oscillation in nanoscale superconducting ring / T. Suzuki, M. Hayashi and H. Ebisawa. Frustrated CDW states in topological crystals / K. Kuboki ... [et al.]. Law of growth in topological crystal / M. Tsubota ... [et al.]. Synthesis and electric properties of NbS[symbol]: possibility of room temperature charge density wave devices / H. Nobukane ... [et al.]. How does a single crystal become a Möbius strip? / T. Matsuura ... [et al.]. Development of X-ray analysis method for topological crystals / K. Yamamoto ... [et al.] -- III. Topological materials. Femtosecond-timescale structure dynamics in complex materials: the case of (NbSe[symbol])[symbol]I / D. Dvorsek and D. Mihailovic. Ultrafast dynamics of charge-density-wave in topological crystals / K. Shimatake ... [et al.]. Topology in morphologies of a folded single-chain polymer / Y. Takenaka, D. Baigl and K. Yoshikawa. One to two-dimensional conversion in topological crystals / T. Toshima, K. Inagaki and S. Tanda. Topological change of Fermi surface in Bismuth under high pressure / M. Kasami ... [et al.]. Topological change of 4, 4'-bis[9-dicarbazolyl]-2, 2'-biphenyl (CBP) by international rearrangement / K. S. Son ... [et al.]. Spin dynamics in Heisenberg triangular system VI5 cluster studied by [symbol]H-NMR / Y. Furukawa ... [et al.]. STM/STS on NbSe[symbol] nanotubes / K. Ichimura ...[et al.]. 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 origin / H. Hori and S, Yamamoto. Topological aspects of wave function statistics at the Anderson transition / H. Obuse and K. Yakubo. Metal-insulator transition in 1D correlated disorder / H. Shima and T. Nakayama. Superconductivity in URu[symbol]Si[symbol] under high pressure / K. Tenya ...[et al.] -- VI. Topology in optics. Optical vorticulture / M. V. Berry. The topology of vortex lines in light beams / M. J. Padgett ... [et al.]. Optical spin vortex: topological objects in nonlinear polarization optics / H. Kuratsuji and S. Kakigi. Coherent dynamics of collective motion in the NbSe[symbol] charge density wave state / Y. Toda ... [et al.]. Coherent collective excitation of charge-density wave in the commensurate phase of the TaS[symbol] compound / T. Minami ... [et al.]. Real time imaging of surface acoustic waves on topological structures / H. Yamazaki, O. B. Wright and O. Matsuda. Optical vortex generation for characterization of topological materials / Y. Tokizane ... [et al.]. Real time imaging techniques for surface waves on topological structures / T. Tachizaki ... [et al.]. Nonlinear oscillations of the Stokes parameters in birefringent media / R. Seto, H. Kuratsuji and R. Botet. Phonon vortex localized in a quantum wire / N. Nishiguchi -- VII. Topology in quantum device. Quantum device applications of mesoscopic superconductivity / P. J. Hakonen. Theory of current-driven domain wall dynamics / G. Tatara ... [et al.]. Squid of a Ruthenate superconductor / Y. Asano, Y. Tanaka and S. Kashiwaya. Path integral formalism for quantum tunneling of relativistic fluxon / K. Konno, T. Fujii and N. Hatakenaka. Experimental study of two and three-dimensional superconducting networks / S. Tsuchiya ... [et al.].

  17. 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

  18. 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

  19. Second-Order Algebraic Theories

    NASA Astrophysics Data System (ADS)

    Fiore, Marcelo; Mahmoud, Ola

    Fiore and Hur [10] recently introduced a conservative extension of universal algebra and equational logic from first to second order. Second-order universal algebra and second-order equational logic respectively provide a model theory and a formal deductive system for languages with variable binding and parameterised metavariables. This work completes the foundations of the subject from the viewpoint of categorical algebra. Specifically, the paper introduces the notion of second-order algebraic theory and develops its basic theory. Two categorical equivalences are established: at the syntactic level, that of second-order equational presentations and second-order algebraic theories; at the semantic level, that of second-order algebras and second-order functorial models. Our development includes a mathematical definition of syntactic translation between second-order equational presentations. This gives the first formalisation of notions such as encodings and transforms in the context of languages with variable binding.

  20. Order classes of dihedral groups

    NASA Astrophysics Data System (ADS)

    Al-Hasanat, Bilal; Ahmad, Azhana; Sulaiman, Hajar

    2014-07-01

    The order of an element x in a finite group G is the smallest positive integer k, such that xk is the group identity. The set of all possible such orders joint with the number of elements that each order referred to, is called the order classes of G. The conjugacy classes of dihedral groups already known, the conjugacy classes is a refinement partition to the order classes. In this paper, the order classes of dihedral groups are derived. In addition, clarifications for some cases related to the size of the groups were given.

  1. Nursing Aides, Orderlies, and Attendants

    MedlinePlus

    ... become certified. Orderlies generally have at least a high school diploma. Pay The median annual wage for nursing ... competency exam. Orderlies generally have at least a high school diploma. Education and Training Nursing assistants must complete ...

  2. 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.

  3. Order metrics and order maps of octahedron packings

    NASA Astrophysics Data System (ADS)

    Liu, Lufeng; Lu, Peng; Meng, Lingyi; Jin, Weiwei; Li, Shuixiang

    2016-02-01

    We apply the ideal octahedron model and the relaxation algorithm in generating octahedron packings. The cubatic order parameter [P4]1, bond-orientational order metric Q6, and local cubatic order parameter P4local of the packings are calculated and their correlations with the packing density are investigated in the order maps. The border curve of packing density separates the geometrically feasible and infeasible regions in the order maps. Observing the transition phenomenon on the border curve, we propose the concept of the maximally dense random packing (MDRP) as the densest packing in the random state in which the particle positions and orientations are randomly distributed and there is no nontrivial spatial correlations among particles. The MDRP characterizes the onset of nontrivial spatial correlations among particles. A special packing with a density about 0.7 is found in the order maps and considered to be the MDRP of octahedra. The P4local is proposed as a new order parameter for octahedron packings, which measures the average order degree in the neighborhoods of particles. The [P4]1, Q6 and P4local evaluate the order degree of orientation, bond orientation and local structures, respectively and are applied simultaneously to measure the order degree of the octahedron packings. Their thresholds in the random state are determined by Monte Carlo simulations.

  4. 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

  5. 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.

  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, 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  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. 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...

  14. 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...

  15. 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...

  16. 77 FR 10719 - Order Renewing Order Temporarily Denying Export Privileges

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... published in the Federal Register on August 31, 2011. See 76 FR 54198. I. Procedural History On March 17... Bureau of Industry and Security Order Renewing Order Temporarily Denying Export Privileges Mahan Airways... further violation of the Regulations and the TDO on the routes of Iran Air, an Iranian Government...

  17. 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

  18. 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…

  19. 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…

  20. 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.

  1. Hierarchical Ordering of Reticular Networks

    PubMed Central

    Mileyko, Yuriy; Edelsbrunner, Herbert; Price, Charles A.; Weitz, Joshua S.

    2012-01-01

    The structure of hierarchical networks in biological and physical systems has long been characterized using the Horton-Strahler ordering scheme. The scheme assigns an integer order to each edge in the network based on the topology of branching such that the order increases from distal parts of the network (e.g., mountain streams or capillaries) to the root of the network (e.g., the river outlet or the aorta). However, Horton-Strahler ordering cannot be applied to networks with loops because they they create a contradiction in the edge ordering in terms of which edge precedes another in the hierarchy. Here, we present a generalization of the Horton-Strahler order to weighted planar reticular networks, where weights are assumed to correlate with the importance of network edges, e.g., weights estimated from edge widths may correlate to flow capacity. Our method assigns hierarchical levels not only to edges of the network, but also to its loops, and classifies the edges into reticular edges, which are responsible for loop formation, and tree edges. In addition, we perform a detailed and rigorous theoretical analysis of the sensitivity of the hierarchical levels to weight perturbations. In doing so, we show that the ordering of the reticular edges is more robust to noise in weight estimation than is the ordering of the tree edges. We discuss applications of this generalized Horton-Strahler ordering to the study of leaf venation and other biological networks. PMID:22701559

  2. 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.

  3. 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.

  4. 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…

  5. 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.

  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. 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…

  8. Children's Order 10 Years on

    ERIC Educational Resources Information Center

    Kerr, Linda

    2006-01-01

    Ten years ago I wrote an article on the Children's Order, which was coming into force in Northern Ireland in October 1996. I examined the principles behind the Children's Order and considered how these principles interacted with the practice of family mediation (at that stage I was Coordinator of the Family Mediation service). Since that date…

  9. Operon Gene Order Is Optimized for Ordered Protein Complex Assembly

    PubMed Central

    Wells, Jonathan N.; Bergendahl, L. Therese; Marsh, Joseph A.

    2016-01-01

    Summary The assembly of heteromeric protein complexes is an inherently stochastic process in which multiple genes are expressed separately into proteins, which must then somehow find each other within the cell. Here, we considered one of the ways by which prokaryotic organisms have attempted to maximize the efficiency of protein complex assembly: the organization of subunit-encoding genes into operons. Using structure-based assembly predictions, we show that operon gene order has been optimized to match the order in which protein subunits assemble. Exceptions to this are almost entirely highly expressed proteins for which assembly is less stochastic and for which precisely ordered translation offers less benefit. Overall, these results show that ordered protein complex assembly pathways are of significant biological importance and represent a major evolutionary constraint on operon gene organization. PMID:26804901

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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)

  15. 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.

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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....

  2. 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....

  3. 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....

  4. 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....

  5. 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....

  6. High Order Continuous Approximation for the Top Order Methods

    NASA Astrophysics Data System (ADS)

    Mazzia, Francesca; Sestini, Alessandra; Trigiante, Donato

    2007-09-01

    The Top Order Methods are a class of linear multistep schemes to be used as Boundary Value Methods and with the feature of having maximal order (2k if k is the number of steps). This often implies that accurate numerical approximations of general BVPs can be produced just using the 3-step TOM. In this work, we consider two different possibilities for defining a continuous approximation of the numerical solution, the standard C1 cubic spline collocating the differential equation at the knots and a C2k-1 spline of degree 2k. The computation of the B-spline coefficients of this higher degree spline requires the solution of N+2k banded linear systems of size 4k×4k. The resulting B-spline function is convergent of order 2k to the exact solution of the continuous BVPs.

  7. Exercise order in resistance training.

    PubMed

    Simão, Roberto; de Salles, Belmiro Freitas; Figueiredo, Tiago; Dias, Ingrid; Willardson, Jeffrey M

    2012-03-01

    Resistance training (RT) is now an integral component of a well rounded exercise programme. For a correct training prescription, it is of the utmost importance to understand the interaction among training variables, such as the load, volume, rest interval between sets and exercises, frequency of sessions, exercise modality, repetition velocity and, finally, exercise order. Sports medicine research has indicated that exercise order is an important variable that affects both acute responses and chronic adaptations to RT programmes. Therefore, the purpose of this review was to analyse and discuss exercise order with relevance to acute responses (e.g. repetition performance) and also the expression of chronic adaptable characteristics (e.g. maximal strength and hypertrophy). To accomplish this purpose, the Scielo, Science Citation Index, National Library of Medicine, MEDLINE, Scopus, SPORTDiscus™ and CINAHL® databases were accessed to locate previously conducted original scientific investigations. The studies reviewed examined both acute responses and chronic adaptations with exercise order as the experimental variable. Generally, with relevance to acute responses, a key finding was that exercise order affects repetition performance over multiple sets, indicating that the total repetitions, and thus the volume, is greater when an exercise is placed at the beginning of an RT session, regardless of the relative amount of muscle mass involved. The pre-exhaustion method might not be an effective technique to increase the extent of neuromuscular recruitment for larger muscle groups (e.g. pectoralis major for the bench press) when preceded by a single-joint movement (e.g. pec-deck fly). With relevance to localized muscular endurance performance, oxygen consumption and ratings of perceived exertion, the limited amount of research conducted thus far indicates that exercise order does not appear to impact the acute expression of these variables. In terms of chronic adaptations, greater strength increases were evident by untrained subjects for the first exercise of a given sequence, while strength increases were inhibited for the last exercise of a given sequence. Additionally, based on strength and hypertrophy (i.e. muscle thickness and volume) effect-size data, the research suggests that exercises be ordered based on priority of importance as dictated by the training goal of a programme, irrespective of whether the exercise involves a relatively large or small muscle group. In summary, exercise order is an important variable that should receive greater attention in RT prescription. When prescribed appropriately with other key prescriptive variables (i.e. load, volume, rest interval between sets and exercises), the exercise order can influence the efficiency, safety and ultimate effectiveness of an RT programme. PMID:22292516

  8. 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)

  9. 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

  10. Order-parameter scaling in fluctuation-dominated phase ordering

    NASA Astrophysics Data System (ADS)

    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 Qm L and find that the mean value obeys the static scaling law ˜L-ϕf (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 (Qm L) 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 /Lz , 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.

  11. Order in a multidimensional system

    PubMed Central

    Roy Frieden, B.; Gatenby, Robert A.

    2014-01-01

    We show that any convex K-dimensional system has a level of order R that is proportional to its level of Fisher information I. The proportionality constant is 1/8 the square of the longest chord connecting two surface points of the system. This result follows solely from the requirement that R decrease under small perturbations caused by a coarse graining of the system. The form for R is generally unitless, allowing the order for different phenomena, or different representations (e.g., using time vs frequency) of a given phenomenom, to be compared objectively. Order R is also invariant to uniform magnification of the system. The monotonic contraction properties of R and I define an arrow of time and imply that they are entropies, in addition to their usual status as informations. This also removes the need for data, and therefore an observer, in derivations of nonparticipatory phenomena that utilize I. Simple graphical examples of the new order measure show that it measures as well the level of “complexity” in the system. Finally, an application to cell growth during enforced distortion shows that a single hydrocarbon chain can be distorted into a membrane having equal order or complexity. Such membranes are prime constituents of living cells. PMID:21867134

  12. Order in a multidimensional system.

    PubMed

    Frieden, B Roy; Gatenby, Robert A

    2011-07-01

    We show that any convex K-dimensional system has a level of order R that is proportional to its level of Fisher information I. The proportionality constant is 1/8 the square of the longest chord connecting two surface points of the system. This result follows solely from the requirement that R decrease under small perturbations caused by a coarse graining of the system. The form for R is generally unitless, allowing the order for different phenomena, or different representations (e.g., using time vs frequency) of a given phenomenom, to be compared objectively. Order R is also invariant to uniform magnification of the system. The monotonic contraction properties of R and I define an arrow of time and imply that they are entropies, in addition to their usual status as informations. This also removes the need for data, and therefore an observer, in derivations of nonparticipatory phenomena that utilize I. Simple graphical examples of the new order measure show that it measures as well the level of "complexity" in the system. Finally, an application to cell growth during enforced distortion shows that a single hydrocarbon chain can be distorted into a membrane having equal order or complexity. Such membranes are prime constituents of living cells. PMID:21867134

  13. 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.

  14. Tree reconstruction from partial orders

    SciTech Connect

    Kannan, S.K. ); Warnow, T.J. )

    1993-01-01

    The problem of constructing trees given a matrix of interleaf distances is motivated by applications in computational evolutionary biology and linguistics. The general problem is to find an edge-weighted tree which most closely approximates the distance matrix. Although the construction problem is easy when the tree exactly fits the distance matrix, optimization problems under all popular criteria are either known or conjectured to be NP-complete. In this paper we consider the related problem where we are given a partial order on the pairwise distances, and wish to construct (if possible) an edge-weighted tree realizing the partial order. In particular we are interested in partial orders which arise from experiments on triples of species, which determine either a linear ordering of the three pairwise distances (called Total Order Model or TOM experiments) or only the pair(s) of minimum distance apart (called Partial Order Model or POM experiments). The POM and TOM experimental model is inspired by the model proposed by Kannan, Lawler, and Warnow for constructing trees from experiments which determine the rooted topology for any triple of species. We examine issues of construction of trees and consistency of TOM and POM experiments, where the trees may either be weighted or unweighted. Using these experiments to construct unweighted trees without nodes of degree two is motivated by a similar problem studied by Winkler, called the Discrete Metric Realization problem, which he showed to be strongly NP-hard. We have the following results: Determining consistency of a set of TOM or POM experiments is NP-Complete whether the tree is weighted or constrained to be unweighted and without degree two nodes. We can construct unweighted trees without degree two nodes from TOM experiments in optimal O(n[sup 3]) time and from POM experiments in O(n[sup 4]) time.

  15. Tree reconstruction from partial orders

    SciTech Connect

    Kannan, S.K.; Warnow, T.J.

    1993-03-01

    The problem of constructing trees given a matrix of interleaf distances is motivated by applications in computational evolutionary biology and linguistics. The general problem is to find an edge-weighted tree which most closely approximates the distance matrix. Although the construction problem is easy when the tree exactly fits the distance matrix, optimization problems under all popular criteria are either known or conjectured to be NP-complete. In this paper we consider the related problem where we are given a partial order on the pairwise distances, and wish to construct (if possible) an edge-weighted tree realizing the partial order. In particular we are interested in partial orders which arise from experiments on triples of species, which determine either a linear ordering of the three pairwise distances (called Total Order Model or TOM experiments) or only the pair(s) of minimum distance apart (called Partial Order Model or POM experiments). The POM and TOM experimental model is inspired by the model proposed by Kannan, Lawler, and Warnow for constructing trees from experiments which determine the rooted topology for any triple of species. We examine issues of construction of trees and consistency of TOM and POM experiments, where the trees may either be weighted or unweighted. Using these experiments to construct unweighted trees without nodes of degree two is motivated by a similar problem studied by Winkler, called the Discrete Metric Realization problem, which he showed to be strongly NP-hard. We have the following results: Determining consistency of a set of TOM or POM experiments is NP-Complete whether the tree is weighted or constrained to be unweighted and without degree two nodes. We can construct unweighted trees without degree two nodes from TOM experiments in optimal O(n{sup 3}) time and from POM experiments in O(n{sup 4}) time.

  16. 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

  17. Order-by-order predictions for nuclear and neutron matter

    NASA Astrophysics Data System (ADS)

    Sammarruca, Francesca

    2014-09-01

    We report on ab initio predictions of nuclear and neutron matter obtained within the BHF approach together with chiral forces. The parameters of the two- and many-body forces are constrained by the properties of the two- and the few-nucleon systems and not readjusted when such forces are applied in nuclear matter. Chiral effective field theories are based on a low-momentum expansion (ChPT) valid for momenta less than the chiral symmetry breaking scale, Λ. Therefore, nucleon-nucleon potentials based on ChPT are usually multiplied by a regulator function f (p' , p) = exp [ - (p' / Λ)2n - (p / Λ)2n ] , where 0.5 GeV is a typical choice for the cutoff Λ. Together with power counting, ChPT allows for a systematic development of nuclear forces, where two- and many-body forces emerge on an equal footing at each order. The question we wish to explore is: how good is the rate of convergence of the chiral expansion? Better and better convergence with increasing order should be seen as improved cutoff independence. We will be concerned with the energy per particle in nuclear and neutron matter as well as the symmetry energy. The purpose is to determine the accuracy with which these quantities can be predicted in ChPT, order by order. We report on ab initio predictions of nuclear and neutron matter obtained within the BHF approach together with chiral forces. The parameters of the two- and many-body forces are constrained by the properties of the two- and the few-nucleon systems and not readjusted when such forces are applied in nuclear matter. Chiral effective field theories are based on a low-momentum expansion (ChPT) valid for momenta less than the chiral symmetry breaking scale, Λ. Therefore, nucleon-nucleon potentials based on ChPT are usually multiplied by a regulator function f (p' , p) = exp [ - (p' / Λ)2n - (p / Λ)2n ] , where 0.5 GeV is a typical choice for the cutoff Λ. Together with power counting, ChPT allows for a systematic development of nuclear forces, where two- and many-body forces emerge on an equal footing at each order. The question we wish to explore is: how good is the rate of convergence of the chiral expansion? Better and better convergence with increasing order should be seen as improved cutoff independence. We will be concerned with the energy per particle in nuclear and neutron matter as well as the symmetry energy. The purpose is to determine the accuracy with which these quantities can be predicted in ChPT, order by order. Support from DOE is acknowledged.

  18. 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,…

  19. 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.

  20. 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)

  1. 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…

  2. 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.

  3. 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

  4. Magnetic-field-induced modifications of the electronic structure of Ni(en)2NO2BF4 : A signature of the Haldane gap in the electronic-excitation intensities

    NASA Astrophysics Data System (ADS)

    Long, V. C.; Chou, Y.-H.; Cross, I. A.; Kozen, A. C.; Montague, J. R.; Schundler, E. C.; Wei, X.; McGill, S. A.; Landry, B. R.; Maxcy-Pearson, K. R.; Turnbull, M. M.; Landee, C. P.

    2007-07-01

    Ni(en)2NO2BF4 (NENB) is isostructural to Ni(en)2NO2ClO4 , the well-known Haldane compound. We have measured the near infrared and visible frequency polarized transmittances of NENB as a function of temperature from 6to300K and in magnetic fields (H) up to 30T . We identify near infrared spin-allowed and spin-forbidden (SF) d-d excitations of the Ni2+ ion as well as a Ni2+ -to- NO2- charge-transfer (CT) transition at 2.5eV , confirmed by vibrational fine structure on the CT band due to the nitrite ion. The spin-allowed d-d bands exhibit temperature dependence consistent with vibronic transitions. The spin-forbidden and electron transfer transitions are noticeably sensitive to magnetic field. Above H≈10T , the NENB SF excitation is linearly suppressed by field, whereas the CT transition intensity increases; the onset field agrees with that observed in the high-field magnetization. For comparison, we made the same measurements on a compound having similar near infrared electronic transitions but a different magnetic ground state: the paramagnetic material Ni(en)3(ClO4)2•H2O (NEN3P). The SF bands of NENB are relatively more intense than those of NEN3P, suggesting that a spin exchange mechanism enhances their intensity in NENB, in contrast to activation solely by spin-orbit coupling in NEN3P. The H dependence of the SF band also differs in the two materials; in NEN3P, suppression of the SF intensity commences at H≈0T . In general, the contrasting behaviors of field-sensitive excitations in the Haldane and paramagnetic analog compounds reveal a correlation between the electronic structure and magnetic properties.

  5. Mössbauer study on the magnetic field-induced insulator-to-metal transition in perovskite EU0.6Sr0.4MnO3

    NASA Astrophysics Data System (ADS)

    Nakamura, Shin; Sato, Masami; Morimoto, Shotaro; Nasu, Saburo; Tsunoda, Yorihiko

    We have investigated the spin dynamics of a distorted perovskite EU0.6Sr0.4MnO3 by means of Mössbauer spectroscopy. Below 70 K the exchange interaction grows gradually, and below 42 K the spins tum into a cluster glass state. The magnetic fieldinduced insulator-to-metal (IM) transition at low temperature is a transition from cluster glass to ferromagnet. The induced metallic phase seems to be still in non-uniform electronic state. On the other hand, at 80 K, just above T c of the induced ferromagnet, a metamagnetic transition was observed.

  6. 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.

  7. 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.

  8. 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.

  9. 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 §...

  10. 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 §...

  11. 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 §...

  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. Reducing errant ordered radiology exams.

    PubMed

    Duman, Benjamin; Martin, Patrick

    2012-01-01

    With grant funds, Providence Saint Patrick Hospital set out to reduce the occurrences of errant ordered radiology exams from clinicians. The goal was to also provide a tool that would assist in reducing unwarranted dose from diagnostic imaging modalities. An interactive web based utility for CT protocols was developed, which included ACR Appropriateness Criteria that was easy to use and maintain. The second stage of the program will be expanded to include more modalities, as well as to provide patients with a convenient source of information. PMID:22413608

  14. Biocatalytic induction of supramolecular order

    NASA Astrophysics Data System (ADS)

    Hirst, Andrew R.; Roy, Sangita; Arora, Meenakshi; Das, Apurba K.; Hodson, Nigel; Murray, Paul; Marshall, Stephen; Javid, Nadeem; Sefcik, Jan; Boekhoven, Job; van Esch, Jan H.; Santabarbara, Stefano; Hunt, Neil T.; Ulijn, Rein V.

    2010-12-01

    Supramolecular gels, which demonstrate tunable functionalities, have attracted much interest in a range of areas, including healthcare, environmental protection and energy-related technologies. Preparing these materials in a reliable manner is challenging, with an increased level of kinetic defects observed at higher self-assembly rates. Here, by combining biocatalysis and molecular self-assembly, we have shown the ability to more quickly access higher-ordered structures. By simply increasing enzyme concentration, supramolecular order expressed at molecular, nano- and micro-levels is dramatically enhanced, and, importantly, the gelator concentrations remain identical. Amphiphile molecules were prepared by attaching an aromatic moiety to a dipeptide backbone capped with a methyl ester. Their self-assembly was induced by an enzyme that hydrolysed the ester. Different enzyme concentrations altered the catalytic activity and size of the enzyme clusters, affecting their mobility. This allowed structurally diverse materials that represent local minima in the free energy landscape to be accessed based on a single gelator structure.

  15. 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.

  16. Ordering Phenomena in Undercooled Alloys

    SciTech Connect

    Fultz, Brent

    1997-07-17

    Much of the work performed under this grant was devoted to using modern ideas in kinetics to understand atom movements in metallic alloys far from thermodynamic equilibrium. Kinetics arguments were based explicitly on the vacancy mechanism for atom movements. The emphasis was on how individual atom movements are influenced by the local chemical environment of the moving atom, and how atom movements cause changes in the local chemical environments. The author formulated a kinetic master equation method to treat atom movements on a crystal lattice with a vacancy mechanism. Some of these analyses [3,10,16] are as detailed as any treatment of the statistical kinetics of atom movements in crystalline alloys. Three results came from this work. Chronologically they were (1) A recognition that tracking time dependencies is not necessarily the best way to study kinetic phenomena. If multiple order parameters can be measured in a material, the ''kinetic path'' through the space spanned by these order parameters maybe just as informative about the chemical factors that affect atom movements [2,3,5-7,9-11,14-16,18,19,21,23,24,26,36,37]. (2) Kinetic paths need not follow the steepest gradient of the free energy function (this should be well-known), and for alloys far from equilibrium the free energy function can be almost useless in describing kinetic behavior. This is why the third result surprised me. (3) In cluster approximations with multiple order parameters, saddle points are common features of free energy functions. Interestingly, kinetic processes stall or change time scale when the kinetic path approaches a state at a saddle point in the free energy function, even though these states exist far from thermodynamic equilibrium. The author calls such a state a ''pseudostable'' (falsely stable) state [6,21,26]. I have also studied these phenomena by more ''exact'' Monte Carlo simulations. The kinetic paths showed features similar to those found in analytical theories. The author found that a microstructure with interfaces arranged in space as a periodic minimal surface is a probably an alloy at a saddle point in its free energy function [21,26,37].

  17. 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.

  18. 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.

  19. 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.

  20. Ellipiticity of higher order harmonics

    NASA Astrophysics Data System (ADS)

    Xia, Yuqing; Jaron-Becker, Agnieszka

    2013-05-01

    High-order harmonic generation (HHG) results from the extreme distortion of an electron wave function in a system in the presence of a strong laser field. Since both the ionization and electron recombination steps of HHG process are dependent on the particular symmetry of the active orbital and its orientation with respect to the laser field, HHG provides a unique probe of the electronic properties and structure of a molecule. We investigate in detail how the information is encoded in the intensities and phases of the harmonics. We calculate the spectra and the ellipticity of harmonics including the contributions from all orbitals using Time-Dependent Density Functional Theory (TDDFT) method. The results are compared with calculations within ``Strong Field Approximation'' (SFA) as well as with experiments. We investigate relative contributions from different active orbitals and in particular if it is possible to identify each orbital's contribution. NSF TAMOP (PHY-1068706).

  1. 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.

  2. 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 -∞

  3. Bringing Order to the Chaos

    PubMed Central

    Swanstrom, Lee L.; Park, Adrian; Arregui, Marty; Franklin, Morris; Smith, C Daniel; Blaney, Christina

    2006-01-01

    Background: Since 1993, there has been an increase in the number of postgraduate fellowships in minimally invasive and gastrointestinal (GI) surgery; from 9 in 1993 to more than 80 in 2004. Early on, there was no supervision or accreditation of these fellowships, and they varied widely in content, structure, and quality. This was widely recognized as being a bad situation for fellow applicants and reflected poorly on the specialties of minimally invasive (MI) and GI surgery. In an effort to bring order to this chaotic situation, the Minimally Invasive Surgery Fellowship Council (MISFC) was founded in 1997. Method: In 2003, the MISFC was incorporated with 77 founding member programs. The goal of the MISFC was to develop guidelines for high-quality fellowship training, to provide a forum for the directors of MI and GI fellowships to exchange ideas, formulate training curricula; to establish uniform application and selection dates; and to create an equitable computerized match system for applicants. Results: In 2004, the MISFC has increased to 95 members representing 154 postgraduate fellowship positions. The majority of these positions are primarily laparoscopic in focus, but other aspects of GI surgery including bariatric, general GI, flexible endoscopy, and hepatopancreatobiliary are also represented. Uniform application and selection dates were agreed on in 2001; and in 2003, the Council established a computerized Match, administered by the National Resident Match Program, which was used for the 2004 fellowship selection. A total of 113 positions were open for the match. A total of 248 applicants formally applied to MISFC programs and 130 participated in the match. Ninety-nine positions matched on the December 10th match day, and the remaining 14 programs successfully filled on the following scramble day. Seventeen applicants did not match to a program. Post match polling of program directors and applicants documented a high degree of compliance, usability, and satisfaction with the process. Conclusion: The MISFC has been successful at realizing its goals of bringing order to the past chaos of the MIS and GI fellowship situation. Its current iteration, the Fellowship Council, is in the process of introducing an accreditation process to further ensure the highest quality of postgraduate training in the fields of GI and endoscopic surgery. PMID:16552191

  4. 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..., cease and desist orders, consent orders, and other Commission orders. (a) Informal enforcement proceedings. Informal enforcement proceedings may be conducted by the Commission, through the Office of...

  5. Repeated Red-Black ordering

    NASA Astrophysics Data System (ADS)

    Ciarlet, P.

    1994-09-01

    Hereafter, we describe and analyze, from both a theoretical and a numerical point of view, an iterative method for efficiently solving symmetric elliptic problems with possibly discontinuous coefficients. In the following, we use the Preconditioned Conjugate Gradient method to solve the symmetric positive definite linear systems which arise from the finite element discretization of the problems. We focus our interest on sparse and efficient preconditioners. In order to define the preconditioners, we perform two steps: first we reorder the unknowns and then we carry out a (modified) incomplete factorization of the original matrix. We study numerically and theoretically two preconditioners, the second preconditioner corresponding to the one investigated by Brand and Heinemann [2]. We prove convergence results about the Poisson equation with either Dirichlet or periodic boundary conditions. For a meshsizeh, Brand proved that the condition number of the preconditioned system is bounded byO(h-1/2) for Dirichlet boundary conditions. By slightly modifying the preconditioning process, we prove that the condition number is bounded byO(h-1/3).

  6. Girls, pecking order and smoking.

    PubMed

    Michell, L; Amos, A

    1997-06-01

    Against a background of growing concern about the failure to reduce cigarette smoking amongst young people, particularly girls, this paper attempts to unravel the complex interrelationships between smoking, peer group structure and gender. We were particularly intrigued to explore a recent hypothesis in the literature that suggests that girls who smoke, far from lacking self-esteem, are more self-confident and socially skilled than their non-smoking peers. Sociometric and qualitative analyses revealed that smoking behaviour was indeed shaped by gender, and that the psychosocial processes involved in smoking uptake may be different for boys and than for girls. Peer group structure, consistently described by young people as hierarchical, was closely related to smoking behaviour. Girls at the top of the social pecking order who projected an image of high self-esteem were identified as most likely to smoke, while only a small minority of girls fitted the stereotype of the young female smoker who has poor social skills and low self-esteem. Boys of high social status were less vulnerable, since sport and a desire to be fit to some extent protected them. Our findings raise fundamental questions about the meaning of self-esteem in relation to smoking uptake, arguing instead for an exploration of the term "self-worth". They suggest the need for health education programmes which are sensitive both to gender and to peer group structures. PMID:9194247

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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...

  18. Correlation of electric polarization and magnetic ordering in cobalt chloride thiourea

    NASA Astrophysics Data System (ADS)

    Mun, Eundeok; Wilcox, Jason; Manson, Jamie; Scott, Brian; Tobash, Paul; Bauer, Eric; Zapf, Vivien

    2011-03-01

    The coupling between electricity and magnetism in magneto-electric multiferroics has been intensively investigated in a wide range of transition metal oxides. Recently the material classes have been extended to organo-metallic insulators (sometimes known as metal-organic frameworks or molecular magnets) such as NiCl 2 -4[SC(NH2)2 ], which provides a new arena for designing magneto-electric multiferroics. We have grown single crystals of cobalt chloride thiourea, CoCl 2 -n[SC(NH2)2 ], which forms two different crystal structures with n = 2 and 4. The compound CoCl 2 -2[SC(NH2)2 ] has a triclinic crystal structure with strong magnetic anisotropy and ~ 3 μB /Co ion, indicating S = 3/2 Co spins, and the compound CoCl 2 -4[SC(NH2)2 ] has a tetragonal structure with almost no magnetic anisotropy and 1 μB /Co ion, indicating S = 1/2 Co spins. We will present details of the magnetic field-induced electric polarizations and magnetic properties of these compounds.

  19. 7 CFR 1219.17 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order Definitions § 1219.17...

  20. 7 CFR 1219.17 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order Definitions § 1219.17...

  1. 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...

  2. 7 CFR 1219.17 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order Definitions § 1219.17...

  3. 7 CFR 1219.17 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HASS AVOCADO PROMOTION, RESEARCH, AND INFORMATION Hass Avocado Promotion, Research, and Information Order Definitions § 1219.17...

  4. Tailed bacteriophages: the order caudovirales.

    PubMed

    Ackermann, H W

    1998-01-01

    Tailed bacteriophages have a common origin and constitute an order with three families, named Caudovirales. Their structured tail is unique. Tailed phages share a series of high-level taxonomic properties and show many facultative features that are unique or rare in viruses, for example, tail appendages and unusual bases. They share with other viruses, especially herpesviruses, elements of morphogenesis and life-style that are attributed to convergent evolution. Tailed phages present three types of lysogeny, exemplified by phages lambda, Mu, and P1. Lysogeny appears as a secondary property acquired by horizontal gene transfer. Amino acid sequence alignments (notably of DNA polymerases, integrases, and peptidoglycan hydrolases) indicate frequent events of horizontal gene transfer in tailed phages. Common capsid and tail proteins have not been detected. Tailed phages possibly evolved from small protein shells with a few genes sufficient for some basal level of productive infection. This early stage can no longer be traced. At one point, this precursor phage became perfected. Some of its features were perfect enough to be transmitted until today. It is tempting to list major present-day properties of tailed phages in the past tense to construct a tentative history of these viruses: 1. Tailed phages originated in the early Precambrian, long before eukaryotes and their viruses. 2. The ur-tailed phage, already a quite evolved virus, had an icosahedral head of about 60 nm in diameter and a long non-contractile tail with sixfold symmetry. The capsid contained a single molecule of dsDNA of about 50 kb, and the tail was probably provided with a fixation apparatus. Head and tail were held together by a connector. a. The particle contained no lipids, was heavier than most viruses to come, and had a high DNA content proportional to its capsid size (about 50%). b. Most of its DNA coded for structural proteins. Morphopoietic genes clustered at one end of the genome, with head genes preceding tail genes. Lytic enzymes were probably coded for. A part of the phage genome was nonessential and possibly bacterial. Were tailed phages general transductants since the beginning? 3. The virus infected its host from the outside, injecting its DNA. Replication involved transcription in several waves and formation of DNA concatemers. Novel phages were released by burst of the infected cell after lysis of host membranes by a peptidoglycan hydrolase (and a holin?). a. Capsids were assembled from a starting point, the connector, and around a scaffold. They underwent an elaborate maturation process involving protein cleavage and capsid expansion. Heads and tails were assembled separately and joined later. b. The DNA was cut to size and entered preformed capsids by a headful mechanism. 4. Subsequently, tailed phages diversified by: a. Evolving contractile or short tails and elongated heads. b. Exchanging genes or gene fragments with other phages. c. Becoming temperate by acquiring an integrase-excisionase complex, plasmid parts, or transposons. d. Acquiring DNA and RNA polymerases and other replication enzymes. e. Exchanging lysin genes with their hosts. f. Losing the ability to form concatemers as a consequence of acquiring transposons (Mu) or proteinprimed DNA polymerases (phi 29). Present-day tailed phages appear as chimeras, but their monophyletic origin is still inscribed in their morphology, genome structure, and replication strategy. It may also be evident in the three-dimensional structure of capsid and tail proteins. It is unlikely to be found in amino acid sequences because constitutive proteins must be so old that relationships were obliterated and most or all replication-, lysogeny-, and lysis-related proteins appear to have been borrowed. However, the sum of tailed phage properties and behavior is so characteristic that tailed phages cannot be confused with other viruses. PMID:9891587

  5. 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 change to a more wedge-shaped space available for the acyl chain. PMID:7647244

  6. 6 CFR 27.300 - Orders.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 6 Domestic Security 1 2010-01-01 2010-01-01 false Orders. 27.300 Section 27.300 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.300 Orders. (a) Orders Generally. When the Assistant Secretary determines...

  7. 6 CFR 27.300 - Orders.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 6 Domestic Security 1 2011-01-01 2011-01-01 false Orders. 27.300 Section 27.300 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.300 Orders. (a) Orders Generally. When the Assistant Secretary determines...

  8. 40 CFR 90.503 - Test orders.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Test orders. 90.503 Section 90.503....503 Test orders. (a) The Administrator shall require any testing under this subpart by means of a test order addressed to the manufacturer. (b) The test order will be signed by the Assistant...

  9. 40 CFR 89.503 - Test orders.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Test orders. 89.503 Section 89.503... Test orders. (a) A test order addressed to the manufacturer is required for any testing under this subpart. (b) The test order is signed by the Assistant Administrator for Air and Radiation or his or...

  10. 40 CFR 89.503 - Test orders.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Test orders. 89.503 Section 89.503... Test orders. (a) A test order addressed to the manufacturer is required for any testing under this subpart. (b) The test order is signed by the Assistant Administrator for Air and Radiation or his or...

  11. 7 CFR 1212.15 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HONEY PACKERS AND IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Honey Packers and Importers Research, Promotion, Consumer Education, and Industry Information Order Definitions § 1212.15 Order. “Order” means the...

  12. 7 CFR 1212.15 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HONEY PACKERS AND IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Honey Packers and Importers Research, Promotion, Consumer Education, and Industry Information Order Definitions § 1212.15 Order. “Order” means the...

  13. 7 CFR 1212.15 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HONEY PACKERS AND IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Honey Packers and Importers Research, Promotion, Consumer Education, and Industry Information Order Definitions § 1212.15 Order. “Order” means the...

  14. 7 CFR 1212.15 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HONEY PACKERS AND IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Honey Packers and Importers Research, Promotion, Consumer Education, and Industry Information Order Definitions § 1212.15 Order. “Order” means the...

  15. 7 CFR 1212.15 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE HONEY PACKERS AND IMPORTERS RESEARCH, PROMOTION, CONSUMER EDUCATION AND INDUSTRY INFORMATION ORDER Honey Packers and Importers Research, Promotion, Consumer Education, and Industry Information Order Definitions § 1212.15 Order. “Order” means the...

  16. 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 UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail...

  17. 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 UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS (EFF. UNTIL 7-22-2011) § 952.28 Orders. (a) If an order is issued which...

  18. 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 UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail to...

  19. 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 UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail...

  20. 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 UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.28 Orders. (a) If an order is issued which prohibits delivery of mail...

  1. 10 CFR 218.11 - Supply orders.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Supply orders. 218.11 Section 218.11 Energy DEPARTMENT OF ENERGY OIL STANDBY MANDATORY INTERNATIONAL OIL ALLOCATION Supply Orders § 218.11 Supply orders. (a) A...) The DOE shall serve a copy of the supply order on the firm directed to act as stated therein. (c)...

  2. 10 CFR 218.11 - Supply orders.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Supply orders. 218.11 Section 218.11 Energy DEPARTMENT OF ENERGY OIL STANDBY MANDATORY INTERNATIONAL OIL ALLOCATION Supply Orders § 218.11 Supply orders. (a) A...) The DOE shall serve a copy of the supply order on the firm directed to act as stated therein. (c)...

  3. 10 CFR 218.11 - Supply orders.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 3 2011-01-01 2011-01-01 false Supply orders. 218.11 Section 218.11 Energy DEPARTMENT OF ENERGY OIL STANDBY MANDATORY INTERNATIONAL OIL ALLOCATION Supply Orders § 218.11 Supply orders. (a) A...) The DOE shall serve a copy of the supply order on the firm directed to act as stated therein. (c)...

  4. 10 CFR 218.11 - Supply orders.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Supply orders. 218.11 Section 218.11 Energy DEPARTMENT OF ENERGY OIL STANDBY MANDATORY INTERNATIONAL OIL ALLOCATION Supply Orders § 218.11 Supply orders. (a) A...) The DOE shall serve a copy of the supply order on the firm directed to act as stated therein. (c)...

  5. 6 CFR 27.300 - Orders.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 6 Domestic Security 1 2013-01-01 2013-01-01 false Orders. 27.300 Section 27.300 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.300 Orders. (a) Orders Generally. When the Assistant Secretary determines...

  6. 6 CFR 27.300 - Orders.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 6 Domestic Security 1 2014-01-01 2014-01-01 false Orders. 27.300 Section 27.300 Domestic Security DEPARTMENT OF HOMELAND SECURITY, OFFICE OF THE SECRETARY CHEMICAL FACILITY ANTI-TERRORISM STANDARDS Orders and Adjudications § 27.300 Orders. (a) Orders Generally. When the Assistant Secretary determines...

  7. Order-(incommensurable disorder) phase transitions

    SciTech Connect

    Kovalenko, A.; Nagaev, E.

    1982-01-05

    In first-order phase transitions in magnetic materials exhibiting a high-order spin, the short-range-order vector above the transition point may be incommensurable with the long-range-order vector below the transition point. This theoretical result explains some experiments on UAs. Some other materials which may exhibit this effect are pointed out.

  8. 33 CFR 156.112 - Suspension order.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Suspension order. 156.112 Section... § 156.112 Suspension order. The COTP or OCMI may issue a suspension order to suspend transfer operations... OCMI is unable to verify compliance with the regulations through an inspection. A suspension order:...

  9. 33 CFR 156.112 - Suspension order.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Suspension order. 156.112 Section... § 156.112 Suspension order. The COTP or OCMI may issue a suspension order to suspend transfer operations... OCMI is unable to verify compliance with the regulations through an inspection. A suspension order:...

  10. 33 CFR 156.112 - Suspension order.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Suspension order. 156.112 Section... § 156.112 Suspension order. The COTP or OCMI may issue a suspension order to suspend transfer operations... OCMI is unable to verify compliance with the regulations through an inspection. A suspension order:...

  11. 33 CFR 156.112 - Suspension order.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Suspension order. 156.112 Section... § 156.112 Suspension order. The COTP or OCMI may issue a suspension order to suspend transfer operations... OCMI is unable to verify compliance with the regulations through an inspection. A suspension order:...

  12. 49 CFR 109.17 - Emergency Orders.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Emergency Orders. 109.17 Section 109.17... PROGRAM PROCEDURES Emergency Orders § 109.17 Emergency Orders. (a) Determination of imminent hazard. When... emergency restrictions, prohibitions, recalls, or out-of-service orders, without advance notice or...

  13. 49 CFR 109.17 - Emergency Orders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Emergency Orders. 109.17 Section 109.17... TRANSPORTATION HAZARDOUS MATERIALS PROCEDURAL REGULATIONS FOR OPENING OF PACKAGES, EMERGENCY ORDERS, AND EMERGENCY RECALLS Emergency Orders § 109.17 Emergency Orders. (a) Determination of imminent hazard. When...

  14. 49 CFR 109.17 - Emergency Orders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Emergency Orders. 109.17 Section 109.17... TRANSPORTATION HAZARDOUS MATERIALS PROCEDURAL REGULATIONS FOR OPENING OF PACKAGES, EMERGENCY ORDERS, AND EMERGENCY RECALLS Emergency Orders § 109.17 Emergency Orders. (a) Determination of imminent hazard. When...

  15. 19 CFR 210.76 - Modification or rescission of exclusion orders, cease and desist orders, and consent orders.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 3 2014-04-01 2014-04-01 false Modification or rescission of exclusion orders, cease and desist orders, and consent orders. 210.76 Section 210.76 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND...

  16. 19 CFR 210.76 - Modification or rescission of exclusion orders, cease and desist orders, and consent orders.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Modification or rescission of exclusion orders, cease and desist orders, and consent orders. 210.76 Section 210.76 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND...

  17. 19 CFR 210.76 - Modification or rescission of exclusion orders, cease and desist orders, and consent orders.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 3 2013-04-01 2013-04-01 false Modification or rescission of exclusion orders, cease and desist orders, and consent orders. 210.76 Section 210.76 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND...

  18. 19 CFR 210.76 - Modification or rescission of exclusion orders, cease and desist orders, and consent orders.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 3 2012-04-01 2012-04-01 false Modification or rescission of exclusion orders, cease and desist orders, and consent orders. 210.76 Section 210.76 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND...

  19. 19 CFR 210.76 - Modification or rescission of exclusion orders, cease and desist orders, and consent orders.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 3 2011-04-01 2011-04-01 false Modification or rescission of exclusion orders, cease and desist orders, and consent orders. 210.76 Section 210.76 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND...

  20. Visual perception of order-disorder transition

    PubMed Central

    Katkov, Mikhail; Harris, Hila; Sagi, Dov

    2015-01-01

    Our experience with the natural world, as composed of ordered entities, implies that perception captures relationships between image parts. For instance, regularities in the visual scene are rapidly identified by our visual system. Defining the regularities that govern perception is a basic, unresolved issue in neuroscience. Mathematically, perfect regularities are represented by symmetry (perfect order). The transition from ordered configurations to completely random ones has been extensively studied in statistical physics, where the amount of order is characterized by a symmetry-specific order parameter. Here we applied tools from statistical physics to study order detection in humans. Different sets of visual textures, parameterized by the thermodynamic temperature in the Boltzmann distribution, were designed. We investigated how much order is required in a visual texture for it to be discriminated from random noise. The performance of human observers was compared to Ideal and Order observers (based on the order parameter). The results indicated a high consistency in performance across human observers, much below that of the Ideal observer, but well-approximated by the Order observer. Overall, we provide a novel quantitative paradigm to address order perception. Our findings, based on this paradigm, suggest that the statistical physics formalism of order captures regularities to which the human visual system is sensitive. An additional analysis revealed that some order perception properties are captured by traditional texture discrimination models according to which discrimination is based on integrated energy within maps of oriented linear filters. PMID:26113826

  1. 36 CFR 261.50 - Orders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... in Areas Designated by Order § 261.50 Orders. (a) The Chief, each Regional Forester, each Experiment... Forester, each Experiment Station Director, the Administrator of the Lake Tahoe Basin Management Unit...

  2. 36 CFR 261.50 - Orders.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in Areas Designated by Order § 261.50 Orders. (a) The Chief, each Regional Forester, each Experiment... Forester, each Experiment Station Director, the Administrator of the Lake Tahoe Basin Management Unit...

  3. 46 CFR Sec. 7 - Job order numbering.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP Contract number shall be inserted in every job order and supplemental...

  4. 46 CFR Sec. 7 - Job order numbering.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP Contract number shall be inserted in every job order and supplemental...

  5. 46 CFR Sec. 7 - Job order numbering.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP Contract number shall be inserted in every job order and supplemental...

  6. 46 CFR Sec. 7 - Job order numbering.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP Contract number shall be inserted in every job order and supplemental...

  7. 46 CFR Sec. 7 - Job order numbering.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... REPAIRS UNDER NATIONAL SHIPPING AUTHORITY MASTER LUMP SUM REPAIR CONTRACT-NSA-LUMPSUMREP Sec. 7 Job order numbering. (a) The NSA-LUMPSUMREP Contract number shall be inserted in every job order and supplemental...

  8. 48 CFR 217.504 - Ordering procedures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Acquisitions Under the Economy Act 217.504 Ordering procedures. (a) When the requesting agency is within DoD, a... obtained from the requesting agency and placed in the contract file for the Economy Act order....

  9. 7 CFR 993.101 - Order.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE DRIED PRUNES PRODUCED IN CALIFORNIA... amended, and Order No. 993, as amended (§§ 993.1 through 993.97), regulating the handling of dried...

  10. 7 CFR 993.101 - Order.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE DRIED PRUNES PRODUCED IN CALIFORNIA... amended, and Order No. 993, as amended (§§ 993.1 through 993.97), regulating the handling of dried...

  11. 7 CFR 993.101 - Order.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE DRIED PRUNES PRODUCED IN CALIFORNIA... amended, and Order No. 993, as amended (§§ 993.1 through 993.97), regulating the handling of dried...

  12. 7 CFR 993.101 - Order.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE DRIED PRUNES PRODUCED IN CALIFORNIA... amended, and Order No. 993, as amended (§§ 993.1 through 993.97), regulating the handling of dried...

  13. 7 CFR 993.101 - Order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE DRIED PRUNES PRODUCED IN CALIFORNIA... amended, and Order No. 993, as amended (§§ 993.1 through 993.97), regulating the handling of dried...

  14. 40 CFR 90.503 - Test orders.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... for Air and Radiation or his or her designee. The test order will be delivered in person by an EPA... test order. Notwithstanding the fact that a manufacturer has submitted the list, the Administrator...

  15. 40 CFR 89.503 - Test orders.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... subpart. (b) The test order is signed by the Assistant Administrator for Air and Radiation or his or her..., the list must be submitted prior to issuance of the test order. Notwithstanding the fact that...

  16. 40 CFR 90.503 - Test orders.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... for Air and Radiation or his or her designee. The test order will be delivered in person by an EPA... test order. Notwithstanding the fact that a manufacturer has submitted the list, the Administrator...

  17. 40 CFR 90.503 - Test orders.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... for Air and Radiation or his or her designee. The test order will be delivered in person by an EPA... test order. Notwithstanding the fact that a manufacturer has submitted the list, the Administrator...

  18. 1 CFR 8.2 - Orderly development.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 1 General Provisions 1 2010-01-01 2010-01-01 false Orderly development. 8.2 Section 8.2 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER CODE OF FEDERAL REGULATIONS § 8.2 Orderly development. To assure orderly development of the Code of...

  19. 1 CFR 8.2 - Orderly development.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 1 General Provisions 1 2011-01-01 2011-01-01 false Orderly development. 8.2 Section 8.2 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER CODE OF FEDERAL REGULATIONS § 8.2 Orderly development. To assure orderly development of the Code of...

  20. 10 CFR 820.41 - Compliance order.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Compliance order. 820.41 Section 820.41 Energy DEPARTMENT OF ENERGY PROCEDURAL RULES FOR DOE NUCLEAR ACTIVITIES Compliance Orders § 820.41 Compliance order... Nuclear Statute, or a DOE Nuclear Safety Requirement; (b) Mandates a remedy or other action; and,...

  1. Antenna factorization in strongly ordered limits

    SciTech Connect

    Kosower, David A.

    2005-02-15

    When energies or angles of gluons emitted in a gauge-theory process are small and strongly ordered, the emission factorizes in a simple way to all orders in perturbation theory. I show how to unify the various strongly ordered soft, mixed soft-collinear, and collinear limits using antenna factorization amplitudes, which are generalizations of the Catani-Seymour dipole factorization function.

  2. Discrete Fractional Diffusion Equation of Chaotic Order

    NASA Astrophysics Data System (ADS)

    Wu, Guo-Cheng; Baleanu, Dumitru; Xie, He-Ping; Zeng, Sheng-Da

    Discrete fractional calculus is suggested in diffusion modeling in porous media. A variable-order fractional diffusion equation is proposed on discrete time scales. A function of the variable order is constructed by a chaotic map. The model shows some new random behaviors in comparison with other variable-order cases.

  3. 46 CFR 201.74 - Declaratory orders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 8 2011-10-01 2011-10-01 false Declaratory orders. 201.74 Section 201.74 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION POLICY, PRACTICE AND PROCEDURE RULES OF PRACTICE AND PROCEDURE Formal Proceedings, Notice, Pleadings, Replies (Rule 7) § 201.74 Declaratory orders. The Administration may issue a declaratory order...

  4. 32 CFR 726.6 - Travel orders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Travel orders. 726.6 Section 726.6 National... MENTALLY INCOMPETENT MEMBERS OF THE NAVAL SERVICE § 726.6 Travel orders. The Chief of Naval Personnel or the Deputy Commandant, Manpower & Reserve Affairs, may issue travel orders to a member to...

  5. 32 CFR 726.6 - Travel orders.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Travel orders. 726.6 Section 726.6 National... MENTALLY INCOMPETENT MEMBERS OF THE NAVAL SERVICE § 726.6 Travel orders. The Chief of Naval Personnel or the Deputy Commandant, Manpower & Reserve Affairs, may issue travel orders to a member to...

  6. 20 CFR 655.121 - Job orders.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... orders in 20 CFR part 653, subpart F and the requirements set forth in § 655.122. (b) SWA review. (1) The SWA will review the contents of the job order for compliance with the requirements specified in 20 CFR... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Job orders. 655.121 Section 655.121...

  7. 21 CFR 1303.37 - Final order.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Final order. 1303.37 Section 1303.37 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE QUOTAS Hearings § 1303.37 Final order. As... Administrator shall issue his order on the determination or adjustment of the aggregate production quota or...

  8. 21 CFR 1303.37 - Final order.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Final order. 1303.37 Section 1303.37 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE QUOTAS Hearings § 1303.37 Final order. As... Administrator shall issue his order on the determination or adjustment of the aggregate production quota or...

  9. 21 CFR 1303.37 - Final order.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Final order. 1303.37 Section 1303.37 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE QUOTAS Hearings § 1303.37 Final order. As... Administrator shall issue his order on the determination or adjustment of the aggregate production quota or...

  10. 21 CFR 1303.37 - Final order.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Final order. 1303.37 Section 1303.37 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE QUOTAS Hearings § 1303.37 Final order. As... Administrator shall issue his order on the determination or adjustment of the aggregate production quota or...

  11. 21 CFR 1303.37 - Final order.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Final order. 1303.37 Section 1303.37 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE QUOTAS Hearings § 1303.37 Final order. As... Administrator shall issue his order on the determination or adjustment of the aggregate production quota or...

  12. 20 CFR 655.121 - Job orders.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... orders in 20 CFR part 653, subpart F and the requirements set forth in § 655.122. (b) SWA review. (1) The SWA will review the contents of the job order for compliance with the requirements specified in 20 CFR... job order, Form ETA-790, to the SWA serving the area of intended employment for intrastate...

  13. 20 CFR 655.121 - Job orders.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... orders in 20 CFR part 653, subpart F and the requirements set forth in § 655.122. (b) SWA review. (1) The SWA will review the contents of the job order for compliance with the requirements specified in 20 CFR... job order, Form ETA-790, to the SWA serving the area of intended employment for intrastate...

  14. 20 CFR 655.121 - Job orders.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... orders in 20 CFR part 653, subpart F and the requirements set forth in § 655.122. (b) SWA review. (1) The SWA will review the contents of the job order for compliance with the requirements specified in 20 CFR... job order, Form ETA-790, to the SWA serving the area of intended employment for intrastate...

  15. Abel's Theorem Simplifies Reduction of Order

    ERIC Educational Resources Information Center

    Green, William R.

    2011-01-01

    We give an alternative to the standard method of reduction or order, in which one uses one solution of a homogeneous, linear, second order differential equation to find a second, linearly independent solution. Our method, based on Abel's Theorem, is shorter, less complex and extends to higher order equations.

  16. 47 CFR 1.1415 - Other orders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 1 2012-10-01 2012-10-01 false Other orders. 1.1415 Section 1.1415 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Pole Attachment Complaint Procedures § 1.1415 Other orders. The Commission may issue such other orders and...

  17. 47 CFR 1.1415 - Other orders.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 1 2013-10-01 2013-10-01 false Other orders. 1.1415 Section 1.1415 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE Grants by Random Selection Pole Attachment Complaint Procedures § 1.1415 Other orders. The Commission may issue such other orders and...

  18. 1 CFR 8.2 - Orderly development.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 1 General Provisions 1 2014-01-01 2012-01-01 true Orderly development. 8.2 Section 8.2 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER CODE OF FEDERAL REGULATIONS § 8.2 Orderly development. To assure orderly development of the Code of...

  19. 1 CFR 8.2 - Orderly development.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 1 General Provisions 1 2013-01-01 2012-01-01 true Orderly development. 8.2 Section 8.2 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER CODE OF FEDERAL REGULATIONS § 8.2 Orderly development. To assure orderly development of the Code of...

  20. 1 CFR 8.2 - Orderly development.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 1 General Provisions 1 2012-01-01 2012-01-01 false Orderly development. 8.2 Section 8.2 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER CODE OF FEDERAL REGULATIONS § 8.2 Orderly development. To assure orderly development of the Code of...

  1. Extended-range order in glasses

    SciTech Connect

    Ellison, A.J.G.; Price, D.L.; Saboungi, M.L.; Egami, T.; Hu, Rui-Zhong; Howells, W.S.

    1994-03-01

    A new type of order is identified in complex glasses, characterized by diffraction peaks at values of the wave vector below those typical of intermediate-range order. Combined neutron and anomalous x-ray diffraction studies of one glass exhibiting this behavior, vitreous rubidium germanate, indicate it to be associated with chemical ordering of the two cations with respect to each other.

  2. An Analysis of Second-Order Autoshaping

    ERIC Educational Resources Information Center

    Ward-Robinson, Jasper

    2004-01-01

    Three mechanisms can explain second-order conditioning: (1) The second-order conditioned stimulus (CS2) could activate a representation of the first-order conditioned stimulus (CS1), thereby provoking the conditioned response (CR); The CS2 could enter into an excitatory association with either (2) the representation governing the CR, or (3) with a…

  3. 39 CFR 952.30 - Supplemental orders.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 39 Postal Service 1 2013-07-01 2013-07-01 false Supplemental orders. 952.30 Section 952.30 Postal Service UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.30 Supplemental orders. When the Chief Postal Inspector or his or...

  4. 39 CFR 952.30 - Supplemental orders.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Supplemental orders. 952.30 Section 952.30 Postal Service UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.30 Supplemental orders. When the Chief Postal Inspector or his or...

  5. 39 CFR 952.30 - Supplemental orders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Supplemental orders. 952.30 Section 952.30 Postal Service UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.30 Supplemental orders. When the Chief Postal Inspector or his or...

  6. 39 CFR 952.30 - Supplemental orders.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 39 Postal Service 1 2012-07-01 2012-07-01 false Supplemental orders. 952.30 Section 952.30 Postal Service UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS § 952.30 Supplemental orders. When the Chief Postal Inspector or his or...

  7. 39 CFR 952.30 - Supplemental orders.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 39 Postal Service 1 2011-07-01 2011-07-01 false Supplemental orders. 952.30 Section 952.30 Postal Service UNITED STATES POSTAL SERVICE PROCEDURES RULES OF PRACTICE IN PROCEEDINGS RELATIVE TO FALSE REPRESENTATION AND LOTTERY ORDERS (EFF. UNTIL 7-22-2011) § 952.30 Supplemental orders. When the Chief...

  8. Diachronic Reanalysis in French: Resistant Word Orders.

    ERIC Educational Resources Information Center

    Guillory, Helen Gant

    1994-01-01

    Examines word order in French relative clauses, the last clauses to undergo reanalysis to [SVO] word order through Old and Middle French. Analysis shows that although main clauses change from [SVO] to [TVX] to [SVO] in a progressive manner, clauses in "que" show a preference for [TVX] order until the 13th century, with a resurgence in the 16th…

  9. 6 CFR 27.300 - Orders.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 6 Domestic Security 1 2012-01-01 2012-01-01 false Orders. 27.300 Section 27.300 Domestic Security... and Adjudications § 27.300 Orders. (a) Orders Generally. When the Assistant Secretary determines that... civil penalty of not more than $25,000 for each day during which the violation continues. (c)...

  10. 10 CFR 218.11 - Supply orders.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Supply orders. 218.11 Section 218.11 Energy DEPARTMENT OF ENERGY OIL STANDBY MANDATORY INTERNATIONAL OIL ALLOCATION Supply Orders § 218.11 Supply orders. (a) A... supplying the stated volume of oil to a specified recipient including, but not limited to,...

  11. 19 CFR 4.74 - Transportation orders.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Transportation orders. 4.74 Section 4.74 Customs... VESSELS IN FOREIGN AND DOMESTIC TRADES Foreign Clearances § 4.74 Transportation orders. Clearance shall... voyage would be in violation of any provision of any transportation order, regulation, or...

  12. 19 CFR 4.74 - Transportation orders.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Transportation orders. 4.74 Section 4.74 Customs... VESSELS IN FOREIGN AND DOMESTIC TRADES Foreign Clearances § 4.74 Transportation orders. Clearance shall... voyage would be in violation of any provision of any transportation order, regulation, or...

  13. 19 CFR 4.74 - Transportation orders.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 19 Customs Duties 1 2012-04-01 2012-04-01 false Transportation orders. 4.74 Section 4.74 Customs... VESSELS IN FOREIGN AND DOMESTIC TRADES Foreign Clearances § 4.74 Transportation orders. Clearance shall... voyage would be in violation of any provision of any transportation order, regulation, or...

  14. 19 CFR 4.74 - Transportation orders.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 19 Customs Duties 1 2014-04-01 2014-04-01 false Transportation orders. 4.74 Section 4.74 Customs... VESSELS IN FOREIGN AND DOMESTIC TRADES Foreign Clearances § 4.74 Transportation orders. Clearance shall... voyage would be in violation of any provision of any transportation order, regulation, or...

  15. 19 CFR 4.74 - Transportation orders.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Transportation orders. 4.74 Section 4.74 Customs... VESSELS IN FOREIGN AND DOMESTIC TRADES Foreign Clearances § 4.74 Transportation orders. Clearance shall... voyage would be in violation of any provision of any transportation order, regulation, or...

  16. Methodology, Birth Order, Intelligence, and Personality.

    ERIC Educational Resources Information Center

    Michalski, Richard L.; Shackelford, Todd K.

    2001-01-01

    Critiques recent research on the effects of birth order on intelligence and personality, which found that the between-family design revealed that birth order negatively related to intelligence, while the within-family design revealed that birth order was unrelated to intelligence. Suggests that it may not be intelligence that co-varies with birth…

  17. The role of order in distributed programs

    NASA Technical Reports Server (NTRS)

    Birman, Kenneth P.; Marzullo, Keith

    1989-01-01

    The role of order in building distributed systems is discussed. It is the belief that a principle of event ordering underlies the wide range of operating systems mechanisms that were put forward for building robust distributed software. Stated concisely, this principle achieves correct distributed behavior by ordering classes of distributed events that conflict with one another. By focusing on order, simplified descriptions can be obtained and convincingly correct solutions to problems that might otherwise have looked extremely complex. Moreover, it is observed that there are a limited number of ways to obtain order, and that the choice made impacts greatly on performance.

  18. Binocular Combination of Second-Order Stimuli

    PubMed Central

    Zhou, Jiawei; Liu, Rong; Zhou, Yifeng; Hess, Robert F.

    2014-01-01

    Phase information is a fundamental aspect of visual stimuli. However, the nature of the binocular combination of stimuli defined by modulations in contrast, so-called second-order stimuli, is presently not clear. To address this issue, we measured binocular combination for first- (luminance modulated) and second-order (contrast modulated) stimuli using a binocular phase combination paradigm in seven normal adults. We found that the binocular perceived phase of second-order gratings depends on the interocular signal ratio as has been previously shown for their first order counterparts; the interocular signal ratios when the two eyes were balanced was close to 1 in both first- and second-order phase combinations. However, second-order combination is more linear than previously found for first-order combination. Furthermore, binocular combination of second-order stimuli was similar regardless of whether the carriers in the two eyes were correlated, anti-correlated, or uncorrelated. This suggests that, in normal adults, the binocular phase combination of second-order stimuli occurs after the monocular extracting of the second-order modulations. The sensory balance associated with this second-order combination can be obtained from binocular phase combination measurements. PMID:24404180

  19. Hastatic Order in URu2Si2

    NASA Astrophysics Data System (ADS)

    Chandra, Premala; Coleman, Piers; Flint, Rebecca

    2012-02-01

    The hidden order that develops below 17.5K in URu2Si2 has eluded identification for twenty-five years. Here we show that the recent observation of Ising quasiparticles in URu2Si2 suggests a novel ``hastatic order'' (Latin:spear),with a two-component order parameter describing hybridization between electrons and the Ising 5f^2 states of the uranium atoms. Hastatic order breaks time-reversal symmetry by mixing states of different Kramers parity; this accounts for the magnetic anomalies observed in torque magnetometry and the pseudo-Goldstone mode observed in neutron scattering. Hastatic order is predicted to induce a basal-plane magnetic moment of order 0.01μB, a gap to longitudinal spin fluctuations that vanishes continuously at the first-order antiferromagnetic transition and a narrow resonant nematic feature in the scanning tunneling spectra.

  20. First-order inflation. [in cosmology

    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 paper, some models for first-order inflation are discussed, and unique signatures that result if inflation is realized in a first-order transition are emphasized. Some of the history of inflation is reviewed to demonstrate how first-order inflation differs from other models.